JP2021132469A - Four-wheel-drive vehicle - Google Patents

Abstract

To restrain brake torque, equal to or higher than brake torque intended by a driver, from being generated due to a tight corner braking phenomenon.SOLUTION: It is determined whether or not a tight corner braking phenomenon occurs. When it is determined that the tight corner braking phenomenon occurs (a determination in Step S3: YES), Step S4 is executed to limit regeneration brake torque. This restrains drivability from being deteriorated because brake torque equal to or higher than brake torque intended by a driver is generated due to the tight corner braking phenomenon.SELECTED DRAWING: Figure 5

Description

The present invention relates to a four-wheel drive vehicle provided with a rotating machine as a driving force source.

A four-wheel drive vehicle having a rotating machine used as a driving force source and a driving force distribution device for distributing the driving force from the driving force source to the left and right front wheels and the left and right rear wheels is known. The vehicle described in Patent Document 1 is an example thereof, which includes a second electric motor M2 as a rotating machine and a central differential gear device (center differential) 60 as a driving force distribution device. This central differential gear device normally distributes the driving force to the front and rear wheels according to the gear ratio of the central differential gear device, while the distribution rate changes according to the engagement torque when the differential limiting clutch CL is engaged. However, when fully engaged (directly connected state), the driving force is distributed to the front and rear wheels at approximately 50:50. Further, Patent Document 2 describes a technique of applying regenerative braking to the left and right front wheels and the left and right rear wheels via the driving force distribution device by regeneratively controlling the rotating machine.

International release WO2011 / 042951 Japanese Unexamined Patent Publication No. 2000-43696

By the way, in such a four-wheel drive vehicle, a tight corner braking phenomenon may occur in which the rotation of the drive system is braked when a difference in rotational speed between the front and rear wheels occurs during turning. For example, when the differential limiting clutch CL is engaged in the four-wheel drive vehicle described in Patent Document 1, a tight corner braking phenomenon may occur during turning. For this reason, when turning is performed with the regenerative control of the rotating machine and the regenerative brake is applied, a brake torque exceeding the driver's intention is generated due to the tight corner braking phenomenon, resulting in driving operability and the like. Drivability may deteriorate.

The present invention has been made in the background of the above circumstances, and an object of the present invention is to suppress the generation of brake torque more than intended by the driver due to the tight corner braking phenomenon. ..

In order to achieve such an object, the first invention comprises (a) a rotating machine used as a driving force source, a driving force distribution device for distributing the driving force from the driving force source to the left and right front wheels and the left and right rear wheels. A four-wheel drive vehicle including a control device for applying regenerative braking to the left and right front wheels and the left and right rear wheels via the driving force distribution device by regenerative control of the rotating machine (b). The control device determines whether or not a tight corner braking phenomenon has occurred, and limits the regenerative braking when it is determined that the tight corner braking phenomenon has occurred.
The determination of whether or not the tight corner braking phenomenon has occurred includes determining that it has occurred when it is presumed that it has occurred or when it is expected to occur.

According to the second invention, in the four-wheel drive vehicle of the first invention, the control device has a tight corner brake torque according to the magnitude of the tight corner brake torque generated due to the occurrence of the tight corner braking phenomenon. When it is large, the limit amount of the regenerative brake is increased as compared with the case where it is small.

According to the third invention, in the four-wheel drive vehicle of the first invention, (a) each of the left and right front wheels and the left and right rear wheels is provided with wheel brakes capable of controlling the brake torques of the left and right front wheels and the left and right rear wheels. (B) The control device uniformly limits the regenerative brake when it determines that the tight corner braking phenomenon has occurred, and the shortage of the total brake torque of the four-wheel drive vehicle due to the limitation. Is to control the wheel brake so as to be complemented by the wheel brake.

The fourth invention is the four-wheel drive vehicle according to any one of the first to third inventions, wherein the control device has a distribution ratio of the driving force to the left and right front wheels and the left and right rear wheels, a steering angle, a front-rear acceleration, and the like. It is to determine whether or not the tight corner braking phenomenon has occurred by using two or more parameters of left-right acceleration and front-rear left-right wheel speed.

In such a four-wheel drive vehicle, the regenerative braking is limited when the tight corner braking phenomenon occurs, so that the braking torque more than the driver intended due to the tight corner braking phenomenon is generated. It is suppressed that the drivability deteriorates due to the occurrence.

In the second invention, the limit amount of the regenerative brake is increased when the tight corner brake torque is large and when it is small, depending on the magnitude of the tight corner brake torque generated due to the occurrence of the tight corner braking phenomenon. Therefore, deterioration of drivability due to the tight corner braking phenomenon is more appropriately suppressed.

The third invention is the case where the left and right front wheels and the left and right rear wheels are provided with wheel brakes capable of controlling the brake torques of the left and right front wheels and the left and right rear wheels, respectively, and when a tight corner braking phenomenon occurs. While the regenerative braking is uniformly limited, if the total braking torque of the four-wheel drive vehicle is insufficient due to the limitation, the shortage is supplemented by the wheel brake, so drivability due to the tight corner braking phenomenon Deterioration is appropriately suppressed. Further, according to the wheel brake, for example, the brake torques of the left and right front wheels and the left and right rear wheels can be individually controlled, and it is generally possible to control the brake torque more easily and appropriately according to the vehicle condition as compared with the regenerative brake. Therefore, the total brake torque of the four-wheel drive vehicle can be appropriately controlled.

The fourth invention is tight corner braking using two or more parameters of the distribution ratio of the driving force to the left and right front wheels and the left and right rear wheels, the steering angle, the front-rear acceleration, the left-right acceleration, and the front-rear left-right wheel speed. Since it is determined whether or not the phenomenon has occurred, it is possible to determine the occurrence of the tight corner braking phenomenon with high accuracy and limit the regenerative braking.

It is a figure explaining the schematic structure of the drive system of the four-wheel drive vehicle to which this invention is applied, and is also the figure which showed the main part of the control function together. It is a skeleton diagram explaining a specific example of the transmission device for HV of FIG. FIG. 5 is an engagement operation table showing the relationship between a plurality of gear stages of a transmission unit provided in the HV transmission device of FIG. 2 and the operation of an engagement device for establishing the gear stages. It is a skeleton diagram explaining a specific example of the driving force distribution device included in the four-wheel drive vehicle of FIG. It is a flowchart explaining the operation of the regenerative brake control part provided in the electronic control device of FIG. This is an example of a time chart showing changes in the operating state of each part when regenerative braking control is executed according to the flowchart of FIG. 5, and is a case where the tight corner brake torque changes in the middle. Another example of a time chart showing changes in the operating state of each part when regenerative braking control is executed according to the flowchart of FIG. 5 is a case where the required braking force changes in the middle. It is a figure explaining another embodiment of this invention, and is the flowchart explaining another aspect of the regenerative brake control part provided in the electronic control device of FIG. This is an example of a time chart showing changes in the operating state of each part when the regenerative braking control is executed according to the flowchart of FIG. It is a figure explaining still another Example of this invention, and is the skeleton figure explaining another example of a driving force distribution device.

As the driving force source, at least a rotating machine may be provided, and an electric vehicle having only a rotating machine and a hybrid type vehicle having a rotating machine and an engine (internal combustion engine) are targeted. The rotating machine is a motor generator that can be selectively used as an electric motor and a generator. When used as an electric motor, it functions as a driving force source, and when used as a generator, a regenerative brake can be applied. .. As the driving force distribution device, for example, an electronically controlled transfer that can continuously change the distribution rate according to the engagement torque of the driving force distribution clutch, a center differential device with a differential limiting clutch, or the like is suitable. .. The driving force distribution clutch or the differential limiting clutch may be, for example, one in which the distribution rate can be continuously adjusted according to the engagement torque, or one in which the distribution rate can be adjusted in two steps by a meshing clutch or the like. Various aspects are possible.

The control device is configured to apply a regenerative brake in response to a required braking force such as by operating the driver's brake pedal, but applies a predetermined regenerative brake during coasting when the required driving force such as accelerator OFF is 0. It may be something to do. The control device sets the limit amount of the regenerative brake when the tight corner brake torque is large and when it is small, depending on the magnitude of the brake torque (tight corner brake torque) generated due to the tight corner braking phenomenon, for example. It is desirable to reduce the regenerative braking torque by the same magnitude as the tight corner brake torque so that the total braking torque of the entire four-wheel drive vehicle does not change, for example. The regenerative braking torque may be limited stepwise according to the tight corner braking torque. Further, when the tight corner braking phenomenon occurs, the regenerative braking torque may be uniformly limited regardless of the magnitude of the tight corner braking torque. That is, it is not always necessary to obtain the tight corner brake torque, it is sufficient to determine whether or not the tight corner braking phenomenon occurs, and the magnitude of the tight corner brake torque generated due to the tight corner braking phenomenon. May be determined step by step.

The tight corner brake torque can be obtained (estimated) by using, for example, the distribution rate of the driving force by the driving force distribution device, the steering angle, the front-rear acceleration, the left-right acceleration, the front-rear left-right wheel speed, and the like. When the distribution rate can be adjusted, the tight corner brake torque changes depending on the distribution rate, so it is desirable to calculate using at least the distribution rate. For example, the tight corner brake torque can be obtained from a predetermined map or the like by using a distribution ratio and a parameter indicating a tight corner such as a steering angle. It is also possible to obtain the tight corner brake torque based on, for example, the deceleration (front-rear acceleration) and braking torque of the vehicle without using the distribution ratio.

The uniform limitation of the regenerative brake can be reduced by a certain amount of torque, reduced by a certain percentage, limited to a certain regenerative braking torque, and the regenerative braking can be stopped. If the total brake torque is insufficient due to the limitation of the regenerative brake, such as when the regenerative brake is stopped, it is desirable to make up for the shortage with the wheel brake. It is desirable that the four wheel brakes provided on the left and right front wheels and the left and right rear wheels can electrically control the brake torques of the left and right front wheels and the left and right rear wheels independently, but the front wheels and the rear wheels can be controlled independently. However, various aspects are possible.

Hereinafter, examples of the present invention will be described in detail with reference to the drawings. In the following examples, the drawings are appropriately simplified or deformed, and the dimensional ratios and shapes of each part are not necessarily drawn accurately.

FIG. 1 is a skeleton diagram illustrating a drive system of a four-wheel drive vehicle 10 to which the present invention is applied, and also shows a main part of a control function for various controls in the four-wheel drive vehicle 10. The four-wheel drive vehicle 10 is a front-rear-wheel drive (four-wheel drive) hybrid vehicle based on the front engine rear-wheel drive system (FR). In FIG. 1, the four-wheel drive vehicle 10 includes an engine 12, an HV transmission device 20 connected to the engine 12, and a transfer 22 connected to the HV transmission device 20. A front propeller shaft 24 and a rear propeller shaft 26 are connected to the transfer 22, and the driving force transmitted from the engine 12 and the transmission device 20 for HV to the transfer 22 is transferred to the front propeller shaft 24 and the rear via the transfer 22. It is distributed to the propeller shaft 26, and from the front propeller shaft 24, the left and right front wheels 14l and 14r (hereinafter, unless otherwise specified, are referred to as front wheels 14) via the front wheel differential gear device 28 and the left and right front wheel drive shafts 32l and 32r. .) Is transmitted. Further, from the rear propeller shaft 26, the left and right rear wheels 16l and 16r (hereinafter, when not particularly distinguished, are referred to as rear wheels 16) via the rear wheel differential gear device 30 and the left and right rear wheel drive shafts 34l and 34r. ) Is transmitted. The rear wheels 16 are main drive wheels that serve as drive wheels during both two-wheel drive (2WD) and four-wheel drive (4WD), and the front wheels 14 serve as driven wheels and 4WD during two-wheel drive (2WD). It is an auxiliary drive wheel that becomes a drive wheel when traveling. The engine 12 is an internal combustion engine such as a gasoline engine or a diesel engine, and is used as a driving force source for traveling. The transfer 22 corresponds to a driving force distribution device that distributes the driving force to the front wheels 14 and the rear wheels 16.

FIG. 2 is a skeleton diagram illustrating a specific example of the HV transmission device 20. In FIG. 2, the HV transmission device 20 is an electric differential unit arranged on a common first axis C1 in a transmission case 140 (hereinafter, referred to as a case 140) as a non-rotating member attached to a vehicle body. It includes a 142 and a speed change unit 144 connected to the electric differential unit 142 via a transmission member 148. The electric differential unit 142 is directly connected to the crankshaft of the engine 12 via the TM input shaft 38 or indirectly via a damper or the like (not shown). Since the electric differential unit 142 and the transmission unit 144 are configured substantially symmetrically with respect to the first axis C1, the lower half is omitted in the outline diagram of FIG.

The electric differential unit 142 is integrated with the differential mechanism 146, the first rotating machine M1 which is connected to the differential mechanism 146 so as to be able to transmit power and controls the differential state of the differential mechanism 146, and the transmission member 148. It is provided with a second rotating machine M2 which is connected to the transmission member 148 so as to rotate in. The first rotating machine M1 and the second rotating machine M2 have a function as an electric motor that generates mechanical driving force from electric energy and a function as a generator that generates electric energy from mechanical driving force. It is a motor generator. The second rotary machine M2 functions as a substitute for the engine 12 which is the main driving force source, or as a driving force source (secondary driving force source) which generates a driving force for traveling together with the engine 12. That is, the second rotary machine M2 is a rotary machine used as a driving force source for the four-wheel drive vehicle 10.

The differential mechanism 146 is a differential gear device connected to the engine 12 so as to be able to transmit power. Specifically, a single pinion type planetary gear device is used, and the engine is input to the TM input shaft 38. It is a power distribution mechanism that mechanically distributes the output of 12 to the first rotary machine M1 and the transmission member 148. The differential mechanism 146 meshes with the differential portion sun gear S0 via the differential portion sun gear S0, the differential portion carrier CA0 that supports the differential portion pinion gear P0 so as to rotate and revolve, and the differential portion pinion gear P0. It includes three rotating elements of the differential ring gear R0. The differential unit carrier CA0 is connected to the TM input shaft 38, that is, the engine 12, the differential unit sun gear S0 is connected to the first rotating machine M1, and the differential unit ring gear R0 is connected to the transmission member 148. In the differential mechanism 146 configured in this way, the output of the engine 12 is the same as that of the first rotary machine M1 because the rotating elements are allowed to rotate relative to each other and are in a differential state in which the differential action works. The second rotary machine M2 is rotationally driven by the electric energy generated from the first rotary machine M1 by a part of the output of the distributed engine 12 while being distributed to the transmission member 148. The second rotary machine M2 can also be rotationally driven by supplying electrical energy from a power storage device (not shown). Further, by controlling the rotation speed of the first rotary machine M1, it is possible to continuously change the rotation speed of the transmission member 148 regardless of the rotation speed (engine rotation speed) Ne of the engine 12, and it is an electric type. The gear ratio γ0 [= rotation speed (input rotation speed) Nin of the TM input shaft 38 / rotation speed (intermediate rotation speed) Ntr of the transmission member 148] of the differential unit 142 is continuously changed. That is, the electric differential unit 142 also functions as an electric continuously variable transmission. The input rotation speed Nin is the same as the engine rotation speed Ne, and the intermediate rotation speed Ntr is the same as the rotation speed (M2 rotation speed) Nm2 of the second rotary machine M2.

The transmission unit 144 gradually changes the intermediate rotation speed Ntr, which is the rotation speed of the transmission member 148, and transmits the intermediate rotation speed Ntr to the TM output shaft 154. The transmission unit 144 includes a single pinion type first planetary gear device 150 and a single pinion type second planetary gear device 152, and has a gear ratio γt [= intermediate rotation speed Ntr / TM output shaft 154 rotation speed (output). It is a stepped automatic transmission in which a plurality of gears having different rotation speeds) Nout] are mechanically established. The first planetary gear device 150 meshes with the first sun gear S1 via the first sun gear S1, the first carrier CA1 that supports the first pinion gear P1 so as to rotate and revolve, and the first pinion gear P1. It has three rotating elements. The second planetary gear device 152 meshes with the second sun gear S2 via the second carrier CA2 that supports the second sun gear S2 and the second pinion gear P2 so as to rotate and revolve, and the second ring gear R2. It has three rotating elements.

In the first planetary gear device 150 and the second planetary gear device 152, the first sun gear S1 is selectively connected to the transmission member 148 via the third clutch C3 and the case 140 via the first brake B1. Is selectively linked to. The first carrier CA1 is integrally connected to the second ring gear R2, and the first carrier CA1 and the second ring gear R2 are selectively connected to the transmission member 148 via the second clutch C2, and the first carrier CA1 is connected to the transmission member 148. 2 Selectively connected to the case 140 via the brake B2. The first carrier CA1 and the second ring gear R2 are also connected to the case 140, which is a non-rotating member, via a one-way clutch F1 so that rotation in the same direction as the engine 12 is permitted and rotation in the opposite direction is prohibited. There is. The first ring gear R1 is integrally connected to the second carrier CA2, and the first ring gear R1 and the second carrier CA2 are connected to the TM output shaft 154. The second sun gear S2 is selectively connected to the transmission member 148 via the first clutch C1. The first clutch C1, the second clutch C2, the third clutch C3, the first brake B1, and the second brake B2 (hereinafter, referred to as clutch C and brake B unless otherwise specified) are engaged by a hydraulic actuator. This is a hydraulic friction engagement device, and by engaging each clutch C and brake B according to the engagement operation table shown in FIG. 3, the forward 4th gear stages "1st" to "4th" are established. At the same time, the reverse 1st speed gear stage "Rev" is established. Further, when the clutch C and the brake B are all released, the neutral "N" that cuts off the power transmission is obtained.

FIG. 4 is a skeleton diagram illustrating a specific example of the transfer 22. The transfer 22 is an electronically controlled transfer that can continuously and electrically control the distribution ratio (torque distribution) Rf (= driving force of the front wheels 14 / total driving force of the front wheels 14 and the rear wheels 16) with respect to the front wheels 14. Is. The transfer 22 includes a transfer case 40 (hereinafter referred to as a case 40) as a non-rotating member. The case 40 is integrally connected to the case 140 of the HV transmission device 20. The transfer 22 includes a TF input shaft 42 rotatably supported by the case 40, a rear wheel side output shaft 44 that outputs a driving force to the rear wheels 16, a sprocket-shaped drive gear 46 that outputs a driving force to the front wheels 14, and a TF. The high-low transmission mechanism 48 as an auxiliary transmission that shifts the rotation of the input shaft 42 and transmits it to the rear wheel side output shaft 44, and adjusts the transmission torque transmitted from the rear wheel side output shaft 44 to the drive gear 46, that is, the rear wheels. A common front wheel drive clutch 50 that transmits a part of the driving force of the side output shaft 44 to the drive gear 46, and a 4WD lock mechanism 58 as a dog clutch that integrally connects the rear wheel side output shaft 44 and the drive gear 46. It is provided on the first axis C1. The TF input shaft 42 and the rear wheel side output shaft 44 are concentrically and relatively rotatable with each other, and are supported by the case 40 via a first support bearing 71, a second support bearing (output shaft support bearing) 73, and the like, respectively. The drive gear 46 is concentrically supported by the rear wheel side output shaft 44 via a third support bearing 75 so as to be rotatable relative to the rear wheel side output shaft 44. That is, the TF input shaft 42, the rear wheel side output shaft 44, and the drive gear 46 are each rotatably supported by the case 40 around the first axis C1. Further, the front end (left side in FIG. 4) of the rear wheel side output shaft 44 is rotatably supported by the bearing 77. The TF input shaft 42 is connected to the TM output shaft 154 of the transmission unit 144 via a joint such as a spline so as not to rotate relative to each other.

The high-low transmission mechanism 48 establishes either a high gear stage (high-speed side shift stage with a small gear ratio) H or a low gear stage (low-speed side shift stage with a large gear ratio) L to shift the rotation of the TF input shaft 42. It is transmitted to the rear wheel side output shaft 44. The rear wheel side output shaft 44 is a main drive shaft connected to the rear propeller shaft 26 via a joint (not shown). In the case 40, the transfer 22 has the front wheel side output shaft 52 and the sprocket-shaped driven gear 54 integrally provided on the front wheel side output shaft 52 on the common second axis C2 parallel to the first axis C1. Be prepared for. A front wheel drive chain 56 is wound between the drive gear 46 and the driven gear 54, and the front wheel side is wound from the rear wheel side output shaft 44 via the drive gear 46, the front wheel drive chain 56, and the driven gear 54. The driving force is transmitted to the output shaft 52. The front wheel side output shaft 52 is an auxiliary drive shaft connected to the front propeller shaft 24 via a joint (not shown).

The transfer 22 configured in this way adjusts the transmission torque transmitted to the drive gear 46 by the front wheel drive clutch 50, and transmits the drive force transmitted from the high-low transmission mechanism 48 only to the rear wheels 16. It is distributed to the front wheels 14. Further, the transfer 22 is in a 4WD locked state (directly connected state) in which a rotation difference between the rear propeller shaft 26 and the front propeller shaft 24 is not generated by the 4WD lock mechanism 58, and a 4WD unlocked state in which the rotation difference between them is allowed. Switch to either (released state). That is, the transfer 22 transmits power from the rear wheel side output shaft 44 to the front wheel side output shaft 52 in a state where the transmission torque via the front wheel drive clutch 50 is zero and the 4WD lock mechanism 58 is released. On the other hand, when torque is transmitted via the front wheel drive clutch 50 or the 4WD lock mechanism 58 is directly connected, the drive gear 46, the front wheel drive chain 56, and the driven gear are connected from the rear wheel side output shaft 44. Power is transmitted to the front wheel side output shaft 52 via the 54.

The high-low transmission mechanism 48 includes a single pinion type planetary gear device 60 and a high-low sleeve 62. The planetary gear device 60 is arranged concentrically with respect to the sun gear S connected to the TF input shaft 42 so as not to rotate relative to the first axis C1 and cannot rotate around the first axis C1 in the case 40. It has a connected ring gear R and a carrier CA that supports the sun gear S and a plurality of pinion gears P that mesh with the ring gear R so that they can rotate and revolve around the sun gear S. Therefore, the rotation speed of the sun gear S is constant with respect to the TF input shaft 42, and the rotation speed of the carrier CA is decelerated with respect to the TF input shaft 42. Further, a high side gear tooth 64 is provided on the inner peripheral surface of the sun gear S, and a low side gear tooth 66 having the same diameter as the high side gear tooth 64 is provided on the carrier CA. The high gear tooth 64 is a spline tooth involved in the formation of the high gear stage H that outputs rotation at a constant speed with the TF input shaft 42. The low gear tooth 66 is a spline tooth involved in the formation of the low gear stage L that outputs a rotation slower than the TF input shaft 42. The high-low sleeve 62 is spline-fitted around the first axis C1 so as to be relatively movable in the direction of the first axis C1 (direction parallel to the first axis C1) with respect to the rear wheel side output shaft 44. In addition, it is provided with a fork connecting portion 62a and an outer peripheral tooth 62b integrally provided adjacent to the fork connecting portion 62a. The outer peripheral teeth 62b are selectively meshed with the high-side gear teeth 64 and the low-side gear teeth 66 by moving the high-low sleeve 62 in the direction of the first axis C1. When the high side gear tooth 64 and the outer peripheral tooth 62b mesh with each other, the rotation of the TF input shaft 42 and the constant velocity rotation are transmitted to the rear wheel side output shaft 44, and the low side gear tooth 66 and the outer peripheral tooth 62b mesh with each other. Then, the rotation decelerated with respect to the rotation of the TF input shaft 42 is transmitted to the rear wheel side output shaft 44. The high side gear tooth 64 and the high low sleeve 62 function as a high gear stage clutch forming the high gear stage H, and the low side gear tooth 66 and the high low sleeve 62 function as a low gear stage clutch forming the low gear stage L.

The 4WD lock mechanism 58 is movable relative to the lock tooth 68 provided on the inner peripheral surface of the drive gear 46 and the rear wheel side output shaft 44 in the direction of the first axis C1 and rotates relative to the first axis C1. It includes a lock sleeve 70 that is improperly spline-fitted. On the outer peripheral surface of the lock sleeve 70, an outer peripheral tooth 70a that meshes with the lock tooth 68 by moving the lock sleeve 70 in the direction of the first axis C1 is provided, and 4WD in which the outer peripheral tooth 70a and the lock tooth 68 mesh with each other. In the directly connected state of the lock mechanism 58, a 4WD lock state is formed in which the rear wheel side output shaft 44 and the drive gear 46 are integrally rotated. In this 4WD locked state, the distribution ratio Rf of the driving force with respect to the front wheels 14 Rf≈50%, that is, the ratio of the driving force transmitted to the front wheels 14 to the driving force transmitted to the rear wheels 16 is approximately 50:50.

The high-low sleeve 62 and the lock sleeve 70 are separated from each other in the space between the high-low transmission mechanism 48 and the drive gear 46 in a positional relationship in which the lock sleeve 70 is on the drive gear 46 side in the direction of the first axis C1. It is provided. Between these high-low sleeves 62 and the lock sleeve 70, a preloaded first spring 72 that abuts against each other and urges the high-low sleeve 62 and the lock sleeve 70 to separate from each other is arranged. ing. Further, between the drive gear 46 and the lock sleeve 70, the lock sleeve 70 is urged to the front side so as to come into contact with the spring receiving protrusion 44a of the rear wheel side output shaft 44 and the lock sleeve 70 and separate the lock sleeve 70 from the lock teeth 68. A second spring 74 in a preloaded state is provided. Both the first spring 72 and the second spring 74 are compression coil springs, and the urging force of the first spring 72 is set to be larger than that of the second spring 74. The spring receiving protrusion 44a is a flange portion of the rear wheel side output shaft 44 provided so as to project toward the outer peripheral side in the space inside the drive gear 46 in the radial direction. The high side gear tooth 64 is provided at a front side position away from the lock sleeve 70 from the low side gear tooth 66 in the direction of the first axis C1. The outer peripheral teeth 62b of the high-low sleeve 62 are meshed with the high-side gear teeth 64 by being moved to the high gear position on the front side where the high-low sleeve 62 is separated from the lock sleeve 70, and the high gear stage H is established. Is moved to the low gear position on the rear side (right side in FIG. 4) approaching the lock sleeve 70, so that the low gear stage L is formed by meshing with the low gear teeth 66. The outer peripheral teeth 70a of the lock sleeve 70 are meshed with the lock teeth 68 on the rear side where the lock sleeve 70 approaches the drive gear 46. As the high-low sleeve 62 is moved to the low gear position on the rear side, the lock sleeve 70 is moved to the lock position on the rear side according to the urging force of the first spring 72, and the outer peripheral teeth 70a are meshed with the lock teeth 68. The 4WD lock mechanism 58 is directly connected (4WD lock state). Further, as the high-low sleeve 62 is moved to the high gear position on the front side, it is moved to the unlock position on the front side according to the urging force of the second spring 74, and the meshing between the outer peripheral teeth 70a and the lock teeth 68 is released. Then, the 4WD lock mechanism 58 is released.

The front wheel drive clutch 50 includes a clutch hub 76 connected to the rear wheel side output shaft 44 so as to be relatively non-rotatable, a clutch drum 78 connected to the drive gear 46 so as to be relatively non-rotatable, and a clutch hub 76 and a clutch drum 78. It is a multi-plate friction clutch including a friction engagement element 80 that is disposed between the two and selectively connects and disconnects the two, and a piston 81 that presses the friction engagement element 80. The front wheel drive clutch 50 is arranged on the side opposite to the 4WD lock mechanism 58, that is, on the rear side with the drive gear 46 in the first axis C1 direction, and is provided by a piston 81 that moves to the drive gear 46 side (front side). The frictional engagement element 80 is pressed and frictionally engaged. That is, the front wheel drive clutch 50 adjusts the transmission torque (torque capacity) according to the amount of movement of the piston 81 in a state where the piston 81 is moved to the front side, which is the pressing side, and is in contact with the friction engaging element 80. It becomes a possible torque variable connection state or a complete connection state. On the other hand, when the piston 81 is moved to the rear side, which is the non-pressing side away from the drive gear 46, and does not come into contact with the friction engaging element 80, it is in the released state (blocking state).

In the released state of the 4WD lock mechanism 58 in which the front wheel drive clutch 50 is engaged and the outer peripheral teeth 70a of the lock sleeve 70 and the lock teeth 68 are not engaged, the power between the rear wheel side output shaft 44 and the drive gear 46 is reached. The transmission is cut off, and the driving force transmitted from the HV transmission device 20 is transmitted to only the rear wheels 16 in a 2WD state. In this 2WD state, the high-low transmission mechanism 48 is set to the high gear stage H, so that the high gear two-wheel (H2) traveling mode is established. Further, when the high-low transmission mechanism 48 is in the high gear stage H, the 4WD lock mechanism 58 is in the released state, and the front wheel drive clutch 50 is in the torque variable connection state or the complete connection state, the high gear stage is in the 4WD state, that is, the high gear 4 wheels (H4). ) The driving mode is established. In this H4 driving mode, in the torque variable connection state of the front wheel drive clutch 50, differential rotation between the rear wheel side output shaft 44 and the drive gear 46 is allowed, and the differential state (4WD unlocked state). By controlling the transmission torque of the front wheel drive clutch 50, the high gear four-wheel auto (H4A) driving mode in which the distribution rate Rf of the driving force with respect to the front wheels 14 can be continuously changed is achieved. The control range of the distribution rate Rf in this case is, for example, in the range of about 0% to 50%, that is, in the ratio of the driving force transmitted to the front wheels 14 and the driving force transmitted to the rear wheels 16, 0: 100 to 50: It is in the range of about 50. Further, in the fully connected state of the front wheel drive clutch 50, the rear wheel side output shaft 44 and the drive gear 46 are integrally rotated to be in a 4WD lock state, and the high gear four wheel lock (H4L) traveling mode is set. On the other hand, when the high-low transmission mechanism 48 is in the low gear stage L, the front wheel drive clutch 50 is in the disengaged state, and the 4WD lock mechanism 58 is in the direct connection state (4WD lock state), the low gear four-wheel lock (L4L) traveling mode is set. It is established. The distribution rate Rf of the driving force in both the H4L traveling mode and the L4L traveling mode is approximately 50%.

The transfer 22 includes a high-low transmission mechanism 48, a front wheel drive clutch 50, and a mode switching device 82 that operates a 4WD lock mechanism 58 to switch a traveling mode. The mode switching device 82 includes an electric motor 84, a screw mechanism 86 that converts the rotational motion of the electric motor 84 into a linear motion, and a first transmission mechanism 87 that transmits the linear motion of the screw mechanism 86 to the front wheel drive clutch 50. It has a second transmission mechanism 88 that transmits the linear motion of the screw mechanism 86 to the high-low transmission mechanism 48 and the 4WD lock mechanism 58.

The screw mechanism 86 is arranged concentrically with the first axis C1 on the side opposite to the drive gear 46, that is, on the rear side with respect to the front wheel drive clutch 50, and the screw shaft member 92 and the nut member screwed together. It is equipped with 94. The screw shaft member 92 is arranged in the case 40 so as to be immovable in the direction of the first axis C1 and rotatable around the first axis C1, and is rotationally driven by the electric motor 84 via a worm gear 90 that functions as a reduction mechanism. NS. The worm gear 90 is a gear pair including a worm 98 integrally connected to the motor shaft of the electric motor 84 and a worm wheel 100 integrally fixed to the screw shaft member 92. It is decelerated and transmitted to the screw shaft member 92 via the worm gear 90. The nut member 94 is movable in the direction of the first axis C1 and is arranged so as not to rotate around the first axis C1, and is screwed with the screw shaft member 92 via a plurality of balls 96. When the screw shaft member 92 is rotationally driven by the electric motor 84, the nut member 94 is linearly moved in the direction of the first axis C1.

The first transmission mechanism 87 includes a thrust bearing 101 interposed between the piston 81 of the front wheel drive clutch 50 and the nut member 94, and the piston 81 is relative to the first axis C1 direction via the thrust bearing 101. It is immovably connected to the nut member 94 of the screw mechanism 86 so as to be relatively rotatable around the first axis C1. As a result, the linear motion of the nut member 94 in the screw mechanism 86 is transmitted to the front wheel driving clutch 50 via the piston 81, and the friction engaging element 80 of the front wheel driving clutch 50 is frictionally engaged. The piston 81 corresponds to a pressing member that frictionally engages the friction engaging element 80. The front wheel drive clutch 50 is switched between a cutoff state, a torque variable connection state, and a complete connection state according to the axial position of the nut member 94. Specifically, when the nut member 94 is located on the rear side in the direction of the first axis C1, the piston 81 is separated from the friction engaging element 80 and the front wheel drive clutch 50 is released, and the nut member 94 is released. When it is moved to the front side, the piston 81 comes into contact with the friction engaging element 80, and the front wheel drive clutch 50 is in a torque variable connection state. When the nut member 94 is further moved to the front side, the front wheel drive clutch 50 is fully connected. The distribution rate Rf when the front wheel drive clutch 50 is in the fully connected state is approximately 50%, and the distribution rate Rf when the front wheel drive clutch 50 is in the variable torque connection state is, for example, 0 depending on the engagement torque of the front wheel drive clutch 50. It can be adjusted in the range of% to 50%. That is, as the piston 81 is moved to the front side, the engagement torque of the front wheel drive clutch 50 increases, and the drive force distribution ratio Rf with respect to the front wheels 14 increases. The front wheel drive clutch 50 is a drive force distribution clutch, and corresponds to a distribution adjustment unit capable of adjusting the distribution rate Rf of the drive force with respect to the front wheels 14 and the rear wheels 16.

The second transmission mechanism 88 is arranged on another third axis C3 parallel to the first axis C1, and is fixed to the fork shaft 102 connected to the nut member 94 and the fork shaft 102, and has a high-low sleeve. It includes a shift fork 104 connected to 62. The second transmission mechanism 88 transmits the linear motion force of the nut member 94 in the screw mechanism 86 to the high-low sleeve 62 of the high-low transmission mechanism 48 via the fork shaft 102 and the shift fork 104. A force is applied to each other between the high-low sleeve 62 and the lock sleeve 70 via the first spring 72, and the lock sleeve 70 receives a force from the spring receiving protrusion 44a of the rear wheel side output shaft 44 via the second spring 74. Has been granted. Therefore, the second transmission mechanism 88 transmits the linear motion force of the nut member 94 in the screw mechanism 86 from the fork shaft 102 to the lock sleeve 70 of the 4WD lock mechanism 58 via the high-low sleeve 62.

The fork shaft 102 is movably arranged in the case 40 in the direction of the third axis C3 (the direction parallel to the third axis C3). The fork shaft 102 is connected to the nut member 94 via a waiting mechanism 106, and is mechanically linearly reciprocated in the third axis C3 direction as the nut member 94 reciprocates linearly. The waiting mechanism 106 is arranged on the third axis C3 so as to be slidable in the direction of the third axis C3 with respect to the fork shaft 102, and a pair of flanged cylindrical members 108a having flanges provided at one end facing each other. , 108b, a cylindrical spacer 110 interposed between a pair of flanged cylindrical members 108a, 108b, and a pair of spring members (compression coil springs) 112 arranged in a preloaded state on the outer peripheral side of the spacer 110. It includes a gripping member 114 that is engaged with the flanged cylindrical members 108a and 108b and moves in the direction of the third axis C3, and a connecting member 116 that integrally connects the gripping member 114 and the nut member 94. The gripping member 114 slides the flanged cylindrical members 108a and 108b on the fork shaft 102 by contacting the flanges of the flanged cylindrical members 108a and 108b. The length between the collars of the cylindrical members 108a and 108b with collars in a state where the collars are in contact with the gripping member 114 is longer than the length of the spacer 110. Therefore, the state in which the collars are in contact with the gripping member 114 is formed by the urging force of the spring member 112. Further, the waiting mechanism 106 includes stoppers 118a and 118b provided on the fork shaft 102 so as to limit the separation of the flanged cylindrical members 108a and 108b in the third axis C3 direction. By limiting the separation of the flanged cylindrical members 108a and 108b by the stoppers 118a and 118b, the linear motion force of the nut member 94 can be transmitted to the fork shaft 102 via the gripping member 114. The fork shaft 102 corresponds to a switching shaft.

A shift fork 104 is integrally provided on the fork shaft 102. The shift fork 104 is connected to the fork connecting portion 62a provided on the high-low sleeve 62, and the high-low sleeve 62 is mechanically linearly reciprocated in the direction of the first axis C1 as the fork shaft 102 reciprocates linearly. By doing so, the gear stage of the high-low transmission mechanism 48 can be switched. That is, for example, when the fork shaft 102 is moved to the rear side from the state where the outer peripheral teeth 62b of the high-low sleeve 62 mesh with the high-side gear teeth 64 to form the high gear stage H as shown in FIG. 4, the high-low sleeve 62 is moved to the drive gear 46 side, and the outer peripheral teeth 62b are meshed with the low side gear teeth 66 to establish the low gear stage L. Further, when the fork shaft 102 is moved to the front side from the state where the low gear stage L is established, the high-low sleeve 62 is moved to the side away from the drive gear 46, and the outer peripheral teeth 62b become the high-side gear teeth 64. The high gear stage H is established by being meshed with each other.

The second transmission mechanism 88 is configured to include the first spring 72 and the second spring 74, and mechanically changes the operating state of the 4WD lock mechanism 58 in conjunction with the switching of the gear stage of the high-low transmission mechanism 48. Switch. That is, as shown in FIG. 4, when the high-low transmission mechanism 48 is set to the high gear stage H, the 4WD lock mechanism 58 is in the released state, and the high-low sleeve 62 is moved to the drive gear 46 side to switch to the low gear stage L. Then, the lock sleeve 70 is moved to the lock position on the rear side according to the urging force of the first spring 72, the outer peripheral teeth 70a are meshed with the lock teeth 68, and the 4WD lock mechanism 58 is in a directly connected state (4WD lock state). .. Further, when the high-low sleeve 62 is moved to the front side away from the drive gear 46 and switched to the high gear stage H from the 4WD locked state, the lock sleeve 70 is moved to the front side according to the urging force of the second spring 74. The meshing between the outer peripheral tooth 70a and the lock tooth 68 is released, and the 4WD lock mechanism 58 is released. The fork shaft 102 has a high gear position in which the high-low transmission mechanism 48 is in the high gear stage H and the 4WD lock mechanism 58 is in the released state, and the high-low transmission mechanism 48 is in the low gear stage L and the 4WD lock mechanism 58 is in the third axis C3 direction. It can be moved between the low gear position and the 4WD locked state.

In the piston 81 of the front wheel drive clutch 50, the screw shaft member 92 is rotated in one direction (rotational direction in which the nut member 94 is moved to the front side) by the electric motor 84, and the fork shaft 102 is moved from the low gear position to the high gear position. When it is moved, it is moved to the front side due to the axial movement of the nut member 94 accompanying the rotation of the screw shaft member 92, but does not press the friction engaging element 80. That is, the front wheel drive clutch 50 is held in a cutoff state in which the pressure by the piston 81 is released when the fork shaft 102 is moved to either the low gear position or the high gear position. As a result, when the fork shaft 102 is moved to the low gear position, the L4L traveling mode is established, and when the fork shaft 102 is moved to the high gear position, the H2 traveling mode is established.

On the other hand, when the screw shaft member 92 is further rotated in one direction by the electric motor 84 from the state where the fork shaft 102 is in the high gear position, the piston 81 is in friction with the movement of the nut member 94 toward the front side. The front wheel drive clutch 50 is brought into contact with the compound element 80, and the front wheel drive clutch 50 is in a connected state of transmitting power to the front wheel 14 side, and the H4 traveling mode is established. In this H4 travel mode, the front wheel drive clutch 50 is completely connected to the H4A travel mode in which the front wheel drive clutch 50 is in a torque variable connection state, that is, differential rotation is allowed, according to the axial position of the nut member 94, and the front wheel drive clutch 50 is completely connected. The H4L traveling mode is established.

That is, the mode switching device 82 of this embodiment is switched to L4L traveling mode ⇔ H2 traveling mode ⇔ H4A traveling mode ⇔ H4L traveling mode in that order according to the rotation position of the screw shaft member 92. In other words, the screw shaft member 92 is rotated to the predetermined rotation positions L4L, H2, H4A, and H4L by the electric motor 84, so that the screw shaft member 92 is rotated to the predetermined rotation positions L4L, H2, H4A, and H4L, respectively. , Is established. The H4L position and the H4A position may be determined by controlling the motor torque of the electric motor 84 corresponding to the engagement torque of the front wheel drive clutch 50. The waiting mechanism 106 is configured to allow axial movement of the nut member 94 when switching between H4L traveling mode ⇔ H4A traveling mode ⇔ H2 traveling mode, that is, relative movement with respect to the fork shaft 102.

The transfer 22 includes a shaft positioning mechanism 120 that positions the fork shaft 102 in the high gear position or the low gear position. The shaft positioning mechanism 120 includes an accommodating hole 122 formed on the inner peripheral surface of the case 40 on which the fork shaft 102 slides, a lock ball 124 accommodated in the accommodating hole 122, and a lock ball 124 accommodated in the accommodating hole 122. It is provided with a locking spring 126 for urging the fork shaft 102 side, and a pair of recesses 128h and 128l formed on the outer peripheral surface of the fork shaft 102. Then, the fork shaft 102 is positioned at the high gear position by engaging the lock ball 124 with the recess 128h, and the fork shaft 102 is positioned at the low gear position by engaging the lock ball 124 with the recess 128l. Will be done. The shaft positioning mechanism 120 maintains each gear position of the fork shaft 102 even if the output from the electric motor 84 is stopped at each gear position.

The transfer 22 includes a low gear position detection switch 130 that detects the low gear position of the fork shaft 102. The low gear position detection switch 130 detects that the low gear position has been moved to the low gear position by being brought into contact with the fork shaft 102 that has been moved to the low gear position, for example, with a ball-shaped contact switch. When the low gear position detection switch 130 detects that the vehicle is in the low gear position, for example, an indicator for notifying the driver that the driving mode is L4L is lit. This indicator is provided on a display device 240 arranged on, for example, an instrument panel or the like.

Returning to FIG. 1, the four-wheel drive vehicle 10 also includes a wheel brake drive device 242. The wheel brake drive device 242 has a brake torque of the wheel brakes 36fl, 36fr, 36rl, 36rr (hereinafter, referred to as a wheel brake 36 unless otherwise specified) provided on the front wheels 14l, 14r and the rear wheels 16l, 16r, respectively. The brake oil pressure is electrically controlled according to the wheel brake control signal Sb supplied from the electronic control device 200. The wheel brake drive device 242 has four hydraulic pressures corresponding to the wheel brakes 36fl, 36fr, 36rl and 36rr so that the brake torques of the front wheels 14l and 14r and the rear wheels 16l and 16r can be controlled independently. It is configured with a control valve and the like.

Such a four-wheel drive vehicle 10 includes an electronic control device 200 as a controller for controlling the operation of each part such as the engine 12, the HV transmission device 20, and the transfer 22. The electronic control device 200 includes a so-called microcomputer provided with a CPU, a RAM, a ROM, an input / output interface, and the like, and the CPU uses a temporary storage function of the RAM and signals according to a program stored in the ROM in advance. Various controls are executed by performing processing. If necessary, it is divided into engine control, control of rotating machines M1 and M2, shift control of shift unit 144, travel mode switching control, and the like.

Various information necessary for control is supplied to the electronic control device 200 from various sensors provided in the four-wheel drive vehicle 10. That is, in addition to the low gear position detection switch 130, the engine rotation speed sensor 202, the M1 rotation speed sensor 204, the M2 rotation speed sensor 205, the accelerator opening sensor 206, the required braking force sensor 208, the handle turning angle sensor 210, and the acceleration sensor 212. , Wheel speed sensor 214, motor rotation angle sensor 216, high-low changeover switch 230 operated by the driver to switch between high gear stage H and low gear stage L, 4WD selection operated by the driver to select the 4WD state. From the 4WD lock selection switch 234 operated by the driver to select the switch 232 and 4WD lock state, the shift position sensor 222 that detects the operation position Psh of the shift lever 220 operated by the driver, and the low gear position Plg. Corresponds to engine rotation speed Ne, which is the rotation speed of the engine 12, M1 rotation speed Nm1, which is the rotation speed of the first rotation machine M1, M2 rotation speed Nm2, which is the rotation speed of the second rotation machine M2, and the amount of depression of the accelerator pedal. Accelerator opening θacc, required braking force B corresponding to the depression operation force of the brake pedal, handle turning angle Φ corresponding to the rotation operation amount of the steering wheel, front-rear acceleration Ga of the four-wheel drive vehicle 10, and four-wheel drive vehicle 10. Left / right acceleration Gb, front wheels 14l, 14r, and rear wheels 16l, 16r are selected by the wheel speeds Nwfl, Nwfr, Nwrl, Nwrr, the motor rotation angle θmo, which is the rotation angle of the electric motor 84 of the transfer 22, and the high-low changeover switch 230. 4WDon, which is a signal indicating that the gear stage Shl and 4WD selection switch 232 have been operated, 4LOCKon, which is a signal indicating that the 4WD lock selection switch 234 has been operated, and a signal indicating the operation position Psh of the shift lever 220, etc. Each is supplied. The vehicle speed V can be obtained based on the wheel speeds Nwfl, Nwfr, Nwrl, and Nwrr.

From the electronic control device 200, for example, the engine control signals Se for controlling the engine output via the electronic throttle valve of the engine 12, the fuel injection device, the ignition device, and the like, and the torques (force running torque and regenerative torque) of the rotary machines M1 and M2. ), Rotating machine control signals Sm1 and Sm2, a shift command signal Ssh for switching the gear stage of the transmission unit 144, and a mode switching signal Smo for controlling the rotation angle θmo of the electric motor 84 to switch the traveling mode. The wheel brake control signal Sb for controlling the brake torque (wheel brake torque) Tbw of the wheel brake 36 is an inverter that controls the torque of the engine 12, the rotors M1 and M2, and the hydraulic control circuit for shifting of the transmission unit 144. It is output to the electric motor 84, the wheel brake drive device 242, and the like, respectively. Further, for example, a display signal Si indicating that the L4L traveling mode is set is output to the display device 240 arranged on the instrument panel or the like.

The electronic control device 200 functionally includes a mode switching control unit 250, a wheel brake control unit 254, and a regenerative brake control unit 256, and the mode switching control unit 250 further includes a distribution control unit 252. The electronic control device 200 corresponds to a control device for a four-wheel drive vehicle.

The mode changeover control unit 250 switches the travel modes H4L, H4A, H2, and L4L based on the operation of the high-low changeover switch 230, the 4WD selection switch 232, the 4WD lock selection switch 234, the operating state of the four-wheel drive vehicle 10, and the like. Of these, the L4L driving mode is a driving mode that is preferably selected when traveling off-road such as riverbeds, rocky areas, and steep slopes at low speed with a large torque, and the low gear stage L, that is, the L4L driving mode is selected by operating the high-low changeover switch 230. If so, the electric motor 84 of the mode switching device 82 is controlled to switch to the L4L traveling mode under certain conditions. Further, when the high gear stage H is selected by operating the high-low changeover switch 230, the rotation angle θmo of the electric motor 84 is controlled so as to enter the H2 travel mode, and when the 4WD selection switch 232 is operated in that state, the H4A travels. The rotation angle θmo of the electric motor 84 is controlled so as to be in the mode, and the rotation angle θmo of the electric motor 84 is controlled so as to be in the H4L traveling mode when the 4WD lock selection switch 234 is operated.

The distribution control unit 252 functionally provided in the mode switching control unit 250 controls the engagement torque of the front wheel drive clutch 50, that is, the distribution rate Rf of the driving force with respect to the front wheels 14 when traveling in the H4A travel mode. The distribution rate Rf is controlled according to the driving condition, the vehicle condition, the driving condition, and the like. The engagement torque of the front wheel drive clutch 50 is increased so that the coefficient Rf is high. The engagement torque of the front wheel drive clutch 50 can be controlled by the rotation angle θmo of the electric motor 84 and the motor torque. Further, when the slip of the rear wheel 16 is detected, the engagement torque of the front wheel drive clutch 50 is increased so that the distribution ratio Rf with respect to the front wheel 14 becomes high. In addition, the driving force distribution rate Rf can be controlled by using the steering wheel turning angle Φ, the road gradient, the front-rear acceleration Ga, the left-right acceleration Gb, and the like.

The wheel brake control unit 254 executes wheel brake control for controlling the wheel brake torque Tbw applied to the four-wheel drive vehicle 10 by the wheel brakes 36fl, 36fr, 36rl, and 36rr via the wheel brake drive device 242. The wheel brake control basically calculates a target brake torque Tb * according to the required braking force B, and controls the wheel brake drive device 242 so that the target brake torque Tb * can be obtained. The brake torques of the four wheel brakes 36fl, 36fr, 36rl and 36rr may be the same, but if necessary, the front wheel side wheel brakes 36fl and 36fr and the rear wheel side wheel brakes 36rl and 36rr may be used separately or each wheel brake. The brake torque can be controlled separately for each of 36fl, 36fr, 36rl, and 36rr. For example, the brake torques of the wheel brakes 36fl, 36fr, 36rl, and 36rr can be appropriately controlled according to the driving condition, the vehicle condition, the traveling condition, and the like. The wheel brake torque Tbw is the sum of the brake torques of the four wheel brakes 36fl, 36fr, 36rl and 36rr.

The regenerative brake control unit 256 executes regenerative brake control for applying the regenerative brake torque Tbg to the four-wheel drive vehicle 10 by regenerative control of the second rotary machine M2. In this regenerative brake control, the regenerative brake torque Tbg is applied only to the rear wheels 16 in the H2 driving mode, and in the H4A driving mode, the H4L driving mode, and the L4L driving mode in which the four-wheel drive is performed, the front wheels 14 and the front wheels 14 are applied via the transfer 22. A regenerative braking torque Tbg is applied to the rear wheels 16. The regenerative brake control unit 256 is configured to apply the regenerative brake torque Tbg according to, for example, the required braking force B by the driver's operation of the brake pedal. That is, a part or all of the target brake torque Tb * calculated according to the required braking force B is shared by the regenerative brake torque Tbg by the second rotary machine M2 instead of the wheel brake 36. For example, under certain conditions such as when the required braking force B is weak braking below a predetermined value, the entire target braking torque Tb * can be obtained by the regenerative braking torque Tbg by the second rotary machine M2. Further, in combination with the wheel brake 36, a part of the target brake torque Tb * may be shared by the regenerative brake by the second rotary machine M2. The regenerative brake may be limited or the sharing ratio may be changed according to the distribution rate Rf of the transfer 22. Even when the accelerator is off, that is, when the required driving force is 0 and the required braking force B is 0, the second regenerative brake torque Tbg is applied by the second rotary machine M2 when certain conditions are satisfied. good.

Here, in the H4A running mode, the H4L running mode, and the L4L running mode in which the four-wheel drive running is performed, the regenerative braking torque Tbg by the second rotary machine M2 passes through the transfer 22 to the front wheels 14 and the rear wheels according to the distribution rate Rf. It is transmitted to 16. When the regenerative braking torque Tbg is distributed to the front wheels 14 and the rear wheels 16 in this way, a tight corner braking phenomenon in which the rotation of the drive system is braked when there is a difference in rotational speed between the front wheels 14 and the rear wheels 16 during turning. May occur. When the tight corner braking phenomenon occurs, the total brake torque Tb of the four-wheel drive vehicle 10 becomes larger than the driver intended together with the regenerative braking torque Tbg by the second rotary machine M2, and the drivability deteriorates. there is a possibility. In order to suppress deterioration of drivability due to such a tight corner braking phenomenon, the regenerative brake control unit 256 has steps S1 to S5 in the flowchart of FIG. 5 (hereinafter, the steps are omitted and simply referred to as S1 to S5). The same applies to other flowcharts.) Signal processing is executed, and when a tight corner braking phenomenon occurs, regenerative braking limit control that limits the regenerative braking torque Tbg by the second rotating machine M2 is executed. ..

In S1 of FIG. 5, it is determined whether or not the braking request is made by the user (driver). Whether or not braking is required can be determined, for example, by whether or not the required braking force B is positive or greater than 0, or whether or not it is equal to or greater than a predetermined value close to 0. Even when the accelerator is off when the accelerator pedal depression operation is released, it may be determined that braking is required under certain conditions, such as when it can be considered that the driver desires braking. Not only when a new braking request is made, but also when a regenerative brake or the like by the second rotating machine M2 is already applied according to the braking request. Then, if it is not a braking request, it ends as it is, but if it is determined that a braking request is made, S2 or less is executed.

In S2, the brake torque (tight corner brake torque) Tbt generated due to the tight corner braking phenomenon is calculated. The tight corner brake torque Tbt uses, for example, two or more parameters of the distribution ratio Rf, steering angle Φ, front-rear acceleration Ga, left-right acceleration Gb, and front-rear left-right wheel speeds Nwfl, Nwfr, Nwrl, and Nwrr. Can be calculated. It is also possible to use the vehicle speed V instead of the wheel speeds Nwfl, Nwfr, Nwrl, and Nwrr. Specifically, the actual distribution is based on a map or calculation formula that has been determined in advance by experiments or simulations with the distribution rate Rf, the handle turning angle Φ indicating a tight corner, or the left-right acceleration Gb as parameters. The tight corner brake torque Tbt can be calculated according to the rate Rf and the steering angle Φ or the lateral acceleration Gb. It is also possible to obtain the tight corner brake torque Tbt by comparing the steering wheel turning angle Φ and the left-right acceleration Gb. In addition, the tight corner brake torque Tbt can be calculated by comparing the operating wheel brake torque Tbw and the regenerative brake torque Tbg with the front-rear acceleration Ga. It may be obtained in consideration of the road gradient. Various modes are possible, such as comparing the wheel speed difference between the front and rear wheels with the wheel speed difference between the left and right wheels to obtain the tight corner brake torque Tbt.

In S3, whether or not the tight corner braking phenomenon has occurred is determined based on the tight corner brake torque Tbt obtained in S2. For example, it is determined whether or not the tight corner brake torque Tbt is equal to or greater than a predetermined determination value. The tight corner brake torque Tbt is an estimated value, and whether or not the tight corner braking phenomenon has occurred includes the case where the tight corner braking phenomenon is expected to occur and the case where it is expected to occur. .. If it is determined that the tight corner braking phenomenon has occurred, S4 is executed to limit the regenerative braking torque Tbg, while if it cannot be determined that the tight corner braking phenomenon has occurred, the regenerative braking torque Tbg is limited. Performs normal regenerative braking control based on the user's braking requirements. If the regenerative brake control is not being executed, the process ends as it is. That is, S2 or less may be executed only when the regenerative braking control is executed in response to the user's braking request.

In S4, when the tight corner brake torque Tbt is large, the limit amount of the regenerative brake torque Tbg is increased as compared with the case where the tight corner brake torque Tbt is small, depending on the magnitude of the tight corner brake torque Tbt. Specifically, the regenerative brake torque Tbg is reduced by the same magnitude as the tight corner brake torque Tbt so that the total brake torque Tb does not change.

6 and 7 are examples of time charts showing changes in the operating state of each part when the limit control of the regenerative brake is executed according to the flowchart of FIG. In FIGS. 6 and 7, the time t1 is the time when the brake pedal is depressed, the judgment of S1 becomes YES (affirmative), and the execution of S2 or less is started. These time charts are for the case where the entire target brake torque Tb * calculated according to the required braking force B is shared by the regenerative braking torque Tbg by the second rotating machine M2. Initially, the tight corner brake is used for straight running or the like. Since the torque Tbt = 0, the normal regenerative brake control of S5 is executed following S3, and the regenerative brake torque Tbg is controlled to match the target brake torque Tb *.

At time t2, a tight corner braking phenomenon occurs due to turning, the judgment of S3 becomes YES, and the regenerative braking torque Tbg is limited by executing S4. That is, the regenerative brake torque Tbg is reduced by the tight corner brake torque Tbt so that the total brake torque Tb maintains the target brake torque Tb *. The broken line after the time t2 is a case where the tight corner braking phenomenon does not occur.

After that, in FIG. 6, the tight corner brake torque Tbt decreases at time t3, but the regenerative brake torque Tbg is increased by that amount, so that the total brake torque Tb ≈ target brake torque Tb * is maintained. Further, when the tight corner brake torque Tbt = 0 at time t4, the normal regenerative brake control of S5 is executed following S3, and the regenerative brake torque Tbg is controlled to match the target brake torque Tb *. Will be done. The time t5 is the time when the user's required braking force B = 0, the regenerative braking torque Tbg = 0 is set accordingly, and the regenerative braking control according to the flowchart of FIG. 5 is completed.

FIG. 7 shows a case where the tight corner brake torque Tbt is substantially constant and the user's required braking force B decreases at time t3. By reducing the regenerative braking torque Tbg as the required braking force B decreases, the total braking torque Tb ≈ target braking torque Tb * is maintained. When the required braking force B = 0 at time t4, the regenerative brake torque Tbg = 0 is set earlier by the tight corner brake torque Tbt due to the limitation of the regenerative brake torque Tbg by S4, and the total brake torque Tb is the tight corner brake. Torque Tbt remains. As a result, the regenerative brake control according to the flowchart of FIG. 5 is completed, and when the tight corner brake torque Tbt = 0 at time t5, the total brake torque Tb becomes 0.

As described above, in the four-wheel drive vehicle 10 of the present embodiment, it is determined whether or not the tight corner braking phenomenon has occurred, and when it is determined that the tight corner braking phenomenon has occurred (S3). The judgment is YES), and since S4 is executed to limit the regenerative braking torque Tbg, the total brake torque Tb becomes larger than the driver intended due to the tight corner braking phenomenon, and the drivability is improved. Deterioration is suppressed.

Further, depending on the magnitude of the tight corner brake torque Tbt caused by the occurrence of the tight corner braking phenomenon, when the tight corner brake torque Tbt is large, the limit amount of the regenerative brake is increased as compared with the case where it is small. Therefore, the deterioration of drivability caused by the tight corner braking phenomenon is more appropriately suppressed. In particular, in this embodiment, the regenerative brake torque Tbg is reduced by the tight corner brake torque Tbt, and the total total brake torque Tb is maintained at the target brake torque Tb * determined according to the user's required braking force B, so that the brake torque Tbg is tight. There is no risk of causing discomfort to the driver regardless of the occurrence of the corner braking phenomenon.

Further, the tight corner brake torque Tbt is calculated by using at least a part of the distribution ratio Rf, the steering angle Φ, the front-rear acceleration Ga, the left-right acceleration Gb, and the front-rear left-right wheel speeds Nwfl, Nwfr, Nwrl, and Nwrr. In order to determine whether or not the tight corner braking phenomenon has occurred based on the tight corner braking torque Tbt, drivability is achieved by determining the occurrence of the tight corner braking phenomenon with high accuracy and limiting the regenerative braking torque Tbg. Deterioration can be appropriately suppressed.

Next, another embodiment of the present invention will be described. In the following examples, parts substantially in common with the above examples are designated by the same reference numerals, and detailed description thereof will be omitted.

FIG. 8 is a flowchart executed by the regenerative brake control unit 256 instead of the flowchart of FIG. S1 to S3 and S5 of FIG. 8 are the same as those of FIG. 5, except that S4-1 and S4-2 are provided instead of S4. That is, when it is determined that the tight corner braking phenomenon has occurred and the determination in S3 is YES, the regenerative brake torque Tbg is uniformly set in S4-1 regardless of the magnitude of the tight corner brake torque Tbt. Restrict. In this embodiment, the regenerative braking torque Tbg = 0. Then, in the next S4-2, the shortage of the total brake torque Tb due to the regenerative brake torque Tbg = 0, that is, the amount obtained by subtracting the tight corner brake torque Tbt from the target brake torque Tb * (Tb * -Tbt). Outputs a complement command to the wheel brake control unit 254 to be complemented by the wheel brake 36. The wheel brake control unit 254 controls the wheel brake drive device 242 so that the wheel brake torque Tbw = (Tb * -Tbt) is applied to the four-wheel drive vehicle 10 according to this complementary command. The front-rear wheel distribution and the left-right wheel distribution of the wheel brake torque Tbw at this time can be appropriately controlled according to the driving state, the vehicle state, and the like of the four-wheel drive vehicle 10 regardless of the distribution rate Rf of the transfer 22.

FIG. 9 is an example of a time chart showing changes in the operating state of each part when the limit control of the regenerative brake is executed according to the flowchart of FIG. It is the time when YES is set and the execution of S2 or less is started. Initially, since the tight corner brake torque Tbt = 0 in straight running or the like, the normal regenerative braking control of S5 is executed following S3, and is calculated according to the required braking force B as in FIGS. 6 and 7. The entire target brake torque Tb * is shared by the regenerative brake torque Tbg by the second rotating machine M2. At time t2, a tight corner braking phenomenon occurs due to turning, the judgment of S3 becomes YES, and the regenerative braking torque Tbg is limited by executing S4-1 so that Tbg = 0. Further, when S4-2 is executed, the wheel brake drive device 242 is operated, and the shortage (Tb * -Tbt) of the total brake torque Tb is supplemented by the wheel brake 36, so that the total brake torque Tb is increased. The target brake torque Tb * is maintained.

After that, when the tight corner brake torque Tbt decreases at time t3 and the tight corner braking phenomenon disappears, the normal regenerative brake control of S5 is restored, and the entire target brake torque Tb * is regenerative braked by the second rotary machine M2. The torque Tbg is shared, and the wheel brake torque Tbw = 0. The time t4 is the time when the user's required braking force B = 0, the regenerative braking torque Tbg = 0 is set accordingly, and the regenerative braking control according to the flowchart of FIG. 8 is completed.

Also in this embodiment, if it is determined whether or not the tight corner braking phenomenon has occurred and it is determined that the tight corner braking phenomenon has occurred (the determination in S3 is YES), S4-1 is performed. Since the regenerative braking is limited by the execution, it is possible to prevent the drivability from being deteriorated due to the total braking torque Tb becoming larger than the driver intended due to the tight corner braking phenomenon.

Further, in this embodiment, the regenerative brake torque Tbg is uniformly limited to Tbg = 0, and the shortage (Tb * -Tbt) of the total brake torque Tb due to the limitation is supplemented by the wheel brake 36, so that the corner is tight. Deterioration of drivability due to the braking phenomenon is appropriately suppressed. In particular, since the brake torques of the left and right front wheels 14 and the left and right rear wheels 16 of the wheel brakes 36fl, 36fr, 36rl, and 36rr can be individually controlled, they are more easily controlled than the regenerative brake and appropriately according to the vehicle condition. This is possible, and the total brake torque Tb of the four-wheel drive vehicle 10 can be appropriately controlled.

FIG. 10 is a skeleton diagram illustrating another example of the driving force distribution device. That is, in the above embodiment, the electronically controlled transfer 22 without the center differential device was used, but as shown in FIG. 10, the center differential device 160 provided with the differential limiting clutch CL is used as the driving force distribution device. It can also be adopted. The center differential device 160 is mainly composed of a single pinion type planetary gear device 162 arranged on the first axis C1. The planetary gear device 162 is a 3rd ring gear R3 that meshes with the 3rd sun gear S3 via the 3rd sun gear S3, the 3rd carrier CA3 that supports the 3rd pinion gear P3 so as to rotate and revolve, and the 3rd pinion gear P3. It has two rotating elements. The third carrier CA3 is connected to the TF input shaft 42, and the third ring gear R3 is connected to the rear wheel side output shaft 44. Further, the third sun gear S3 is provided with a drive gear 164, which is connected to the front wheel side output shaft 52 via a front wheel drive chain 56 and a driven gear 54 so as to be able to transmit power. According to such a center differential device 160, the rotating elements S3, R3, and CA3 of the planetary gear device 162 are set to a differential state in which they can rotate relative to each other, so that the TF input is input from the HV transmission device 20. The driving force input to the third carrier CA3 via the shaft 42 is distributed to the third sun gear S3 and the third ring gear R3. This distribution ratio Rf is determined according to the gear ratio ρ of the planetary gear device 162. For example, when the gear ratio ρ (= the number of teeth of the sun gear: the number of teeth of the ring gear) is 3: 7, the driving force with respect to the front wheel side output shaft 52. The distribution rate Rf of is 30%. Since the center differential device 160 is configured substantially symmetrically with respect to the first axis C1, the lower half of the center differential device 160 is omitted from the first axis C1 in the outline diagram of FIG.

The differential limiting clutch CL selectively connects the third carrier CA3 of the planetary gear device 162 and the drive gear 164. The differential limiting clutch CL is a hydraulic friction engaging device similar to the clutch C and the brake B of the transmission unit 144, and for example, a plurality of friction plates stacked on each other are pressed by a hydraulic actuator. It is a wet multi-plate type. When the differential limiting clutch CL is completely engaged, the planetary gear device 162 is integrally rotated, and the driving force is substantially evenly applied to the rear wheel side output shaft 44 and the front wheel side output shaft 52. Will be distributed. That is, the distribution rate Rf of the driving force in this case is about 50%. Further, when the torque capacity of the differential limiting clutch CL, that is, the differential limiting torque is changed, the driving force transmitted to the front wheel side output shaft 52 is changed, and the distribution ratio Rf is set between 30% and 50%. It can be controlled stepwise or continuously. The differential limiting clutch CL corresponds to a distribution adjusting unit that adjusts the distribution rate Rf.

The four-wheel drive vehicle 10 provided with such a center differential device 160 instead of the transfer 22 also has a distribution control unit 252, a wheel brake control unit 254, and a regenerative brake control unit 256, as in the above embodiment. Distribution control, wheel brake control, and regenerative brake control can be performed by using the electronic control device 200, and the same effects as those in the above embodiment can be obtained.

Although the examples of the present invention have been described in detail with reference to the drawings, these are merely embodiments, and the present invention is carried out in a mode in which various modifications and improvements are made based on the knowledge of those skilled in the art. be able to.

10: 4-wheel drive vehicle 14l, 14r: Front wheel 16l, 16r: Rear wheel 22: Transfer (driving force distribution device) 36fl, 36fr, 36rl, 36rr: Wheel brake 160: Center differential device (driving force distribution device) 200: Electronic Control device (control device) M2: Second rotating machine (driving force source, rotating machine) Rf: Distribution rate Φ: Handle turning angle Ga: Front-rear acceleration Gb: Left-right acceleration Nwfl, Nwfr, Nwrl, Nwrr: Wheel speed Tbg: Regeneration Brake torque Tbt: Tight corner brake torque Tbw: Wheel brake torque

Claims (4)

A rotating machine used as a driving force source, a driving force distribution device that distributes the driving force from the driving force source to the left and right front wheels and left and right rear wheels, and the driving force distribution device by regenerative control of the rotating machine. A four-wheel drive vehicle including a control device for applying regenerative braking to the left and right front wheels and the left and right rear wheels.
The control device determines whether or not a tight corner braking phenomenon has occurred, and limits the regenerative braking when it is determined that the tight corner braking phenomenon has occurred. Drive vehicle. The control device has a limit amount of the regenerative brake according to the magnitude of the tight corner brake torque generated due to the occurrence of the tight corner braking phenomenon, when the tight corner brake torque is large as compared with the case where the tight corner brake torque is small. The four-wheel drive vehicle according to claim 1, wherein the size of the vehicle is increased. Each of the left and right front wheels and the left and right rear wheels is provided with wheel brakes capable of controlling the brake torques of the left and right front wheels and the left and right rear wheels.
When the control device determines that the tight corner braking phenomenon has occurred, the regenerative brake is uniformly limited, and the shortage of the total brake torque of the four-wheel drive vehicle due to the limitation is caused by the wheel brake. The four-wheel drive vehicle according to claim 1, wherein the wheel brake is controlled so as to be complemented. The control device uses two or more parameters of the distribution ratio of the driving force to the left and right front wheels and the left and right rear wheels, a steering angle, front-rear acceleration, left-right acceleration, and front-rear left-right wheel speed. The four-wheel drive vehicle according to any one of claims 1 to 3, wherein it is determined whether or not a tight corner braking phenomenon has occurred.

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