JP7043874B2 - Power transmission device - Google Patents

Description

The present invention relates to a power transmission device comprising two systems of power transmission means, a gear transmission mechanism and a belt-type continuously variable transmission, in which one of the selected systems transmits power.

As shown in Patent Document 1, as a power transmission device mounted on a vehicle, a gear transmission mechanism that transmits power by meshing gears and a V-groove width of a primary pulley and a secondary pulley around which a belt is wound are changed. It is known that a belt-type continuously variable transmission that changes the speed ratio steplessly is provided in parallel. In such a complex power transmission mechanism, the range of gear ratios can be expanded as compared with one of the single power transmission mechanisms.

This type of power transmission mechanism has a first clutch that engages when connecting the power of the input shaft to the gear transmission mechanism and a second clutch that engages when the power of the input shaft is connected to the belt type stepless transmission. It includes a clutch, and the control unit controls the first clutch and the second clutch to be selectively engaged.

JP-A-2017-96404

In the power transmission device as described above, it is preferable to control the suppression of the torque acting on the input shaft in order to prevent an excessive torque from being applied for the purpose of protecting the belt type continuously variable transmission, for example.

By the way, the allowable mechanical torque differs between the belt type continuously variable transmission and the gear transmission mechanism, and the latter generally has a larger allowable torque. Therefore, if the torque suppression control for the former is applied to the gear transmission mechanism as it is, the torque limit more than necessary will be applied.

The present invention has been made in view of the above problems, and an object of the present invention is to provide a power transmission device capable of appropriately suppressing torque in a belt-type continuously variable transmission and a gear transmission mechanism, respectively. ..

In order to solve the above-mentioned problems and achieve the object, the power transmission device according to the present invention is a power transmission device that transmits power of an input shaft to an output shaft, and is a gear transmission mechanism that transmits power by meshing gears. , The belt type stepless transmission that changes the speed ratio steplessly by changing the pulley groove width of the primary pulley and the secondary pulley around which the belt is wound, and the gear transmission mechanism or the belt type stepless transmission. It has a selection control unit that selects one and transmits the power of the input shaft to the output shaft, and a torque suppression unit that suppresses the torque applied to the input shaft. The torque suppression unit is the gear transmission mechanism. It is characterized in that the amount of suppression of the torque applied to the input shaft is changed between the case where the power is transmitted to the output shaft and the case where the power is transmitted to the output shaft by the belt type stepless transmission.

In the power transmission device according to the present invention, the torque suppression unit is the torque applied to the input shaft depending on whether the power is transmitted to the output shaft by the gear transmission mechanism or the power is transmitted to the output shaft by the belt type stepless transmission. Change the amount of suppression. As a result, proper torque suppression is performed in each of the belt type continuously variable transmission and the gear transmission mechanism.

FIG. 1 is an outline diagram showing a power transmission device according to an embodiment. FIG. 2 is a flowchart showing a control procedure performed by the power transmission device according to the embodiment.

Hereinafter, embodiments of the power transmission device according to the present invention will be described in detail with reference to the drawings. The present invention is not limited to this embodiment.

First, the vehicle Ve provided with the power transmission device 100 according to the embodiment of the present invention will be described. FIG. 1 is a skeleton diagram showing an example of a vehicle Ve targeted in these embodiments.

As shown in FIG. 1, the vehicle Ve includes an engine 1 as a power source. The engine 1 outputs a predetermined power according to the engine speed Ne. The power output from the engine 1 is a torque converter 2 as a fluid transmission device, an input shaft 3, a forward / backward switching mechanism 4, a belt-type continuously variable transmission 5 (hereinafter referred to as CVT), or a gear train (gear transmission mechanism) 6. , The output shaft 7, the counter gear mechanism 8, the differential gear 9, and the drive shaft 10 are transmitted to the drive wheels 11. A second clutch C2 is provided on the downstream side of the CVT 5 as a clutch for disconnecting the engine 1 from the drive wheels 11. By releasing the second clutch C2, torque cannot be transmitted between the CVT 5 and the output shaft 7, and the CVT 5 in addition to the engine 1 is disconnected from the drive wheels 11.

Specifically, the torque converter 2 includes a pump impeller 2a connected to the engine 1, a turbine runner 2b arranged to face the pump impeller 2a, and a stator 2c arranged between the pump impeller 2a and the turbine runner 2b. Be prepared. The inside of the torque converter 2 is filled with oil as a working fluid. The pump impeller 2a rotates integrally with the crankshaft 1a of the engine 1. The input shaft 3 is connected to the turbine runner 2b so as to rotate integrally. The torque converter 2 is provided with a lockup clutch, and in the engaged state, the pump impeller 2a and the turbine runner 2b rotate integrally, and in the released state, the power output from the engine 1 is transmitted to the turbine runner 2b via the working fluid. Will be done. The stator 2c is held by a fixed portion such as a case via a one-way clutch.

Further, an oil pump 41 is connected to the pump impeller 2a via a transmission mechanism such as a belt mechanism. The oil pump 41 is connected to the crankshaft 1a via the pump impeller 2a and is driven by the engine 1. The oil pump 41 and the pump impeller 2a may be configured to rotate integrally.

The input shaft 3 is connected to the forward / backward switching mechanism 4. When the engine torque is transmitted to the drive wheels 11, the forward / backward switching mechanism 4 switches the direction of the torque acting on the drive wheels 11 between the forward direction and the reverse direction. The forward / backward switching mechanism 4 is composed of a differential mechanism, and in the example shown in FIG. 1, it is configured by a double pinion type planetary gear mechanism. The forward / backward switching mechanism 4 meshes with the sun gear 4S, the ring gear 4R arranged concentrically with respect to the sun gear 4S, the first pinion gear 4P _{1 meshing with the sun gear 4S, the first pinion gear 4P 1 and} the ring gear 4R. The second pinion gear 4P ₂ is provided with a carrier 4C that holds the pinion gears 4P ₁ and 4P ₂ so that they can rotate and revolve. The drive gear 61 of the gear train 6 is connected to the sun gear 4S so as to rotate integrally. The input shaft 3 is connected to the carrier 4C so as to rotate integrally.

Further, a first clutch C1 that selectively and integrally rotates the sun gear 4S and the carrier 4C is provided. By engaging the first clutch C1, the entire forward / backward switching mechanism 4 rotates integrally. Further, a brake B1 for selectively fixing the ring gear 4R so as not to rotate is provided. The first clutch C1 and the brake B1 are hydraulic.

For example, when the first clutch C1 is engaged and the brake B1 is released, the sun gear 4S and the carrier 4C rotate integrally. That is, the input shaft 3 and the drive gear 61 rotate integrally. Further, when the first clutch C1 is released and the brake B1 is engaged, the sun gear 4S and the carrier 4C rotate in opposite directions. That is, the input shaft 3 and the drive gear 61 rotate in opposite directions.

In the vehicle Ve, the CVT 5 which is a continuously variable transmission and the gear train 6 which is a stepped transmission unit or a fixed transmission unit are provided in parallel. As a power transmission path between the input shaft 3 and the output shaft 7, a power transmission path via the CVT 5 and a power transmission path via the gear train 6 are formed in parallel.

The CVT 5 includes a primary pulley 51 that rotates integrally with the input shaft 3 at an input shaft rotation speed of Nin, a secondary pulley 52 that rotates integrally with the secondary shaft 54, and a belt 53 wound around a V-groove formed in the pair of pulleys 51 and 52. To prepare for. The input shaft 3 becomes a primary shaft. Since the winding diameter of the belt 53 is changed by changing the V-groove width of each of the pulleys 51 and 52, the gear ratio γ of the CVT 5 can be continuously changed. The gear ratio γ of the CVT 5 continuously changes within the range from the maximum gear ratio γmax (the gear is the lowest) to the minimum gear ratio γmin (the gear is the highest).

The primary pulley 51 includes a fixed sheave 51a integrated with the input shaft 3, a movable sheave 51b that can move in the axial direction on the input shaft 3, and a primary pressure cylinder 51c that applies thrust to the movable sheave 51b. The sheave surface of the fixed sheave 51a and the sheave surface of the movable sheave 51b face each other to form a V-groove of the primary pulley 51. The primary pressure cylinder 51c is arranged on the back surface side of the movable sheave 51b. The primary pressure supplied to the primary pressure cylinder 51c generates a thrust that moves the movable sheave 51b toward the fixed sheave 51a, and generates a holding pressure on the belt 53 wound around the primary pulley 51.

The secondary pulley 52 includes a fixed sheave 52a integrated with the secondary shaft 54, a movable sheave 52b that can move in the axial direction on the secondary shaft 54, and a secondary pressure cylinder 52c that applies thrust to the movable sheave 52b. The sheave surface of the fixed sheave 52a and the sheave surface of the movable sheave 52b face each other to form a V-groove of the secondary pulley 52. The secondary pressure cylinder 52c is arranged on the back surface side of the movable sheave 52b. The secondary pressure supplied to the secondary pressure cylinder 52c generates a thrust that moves the movable sheave 52b toward the fixed sheave 52a, and generates a holding pressure on the belt 53 wound around the secondary pulley 52.

The second clutch C2 is provided between the secondary shaft 54 and the output shaft 7, and can selectively disconnect the CVT 5 from the output shaft 7. For example, when the second clutch C2 is engaged, the CVT 5 and the output shaft 7 are connected so as to be able to transmit power, and the secondary shaft 54 and the output shaft 7 rotate integrally. That is, the rotation speed Nout1 of the secondary pulley 52 on the upstream side of the second clutch C2 and the output shaft rotation speed Nout2 on the downstream side of the second clutch C2 match (Nout1 = Nout2). On the other hand, when the second clutch C2 is released, the secondary shaft 54 and the output shaft 7 are disconnected from each other so that torque cannot be transmitted, and the engine 1 and the CVT 5 are disconnected from the drive wheels 11.

The second clutch C2 is hydraulic. The engagement elements of the second clutch C2 are configured to be frictionally engaged with each other by a hydraulic actuator. Therefore, if the engaging elements of the second clutch C2 are frictionally engaged with each other in a semi-engaged state, the second clutch C2 can be put into a slip state. In this case, the torque transmitted between the CVT 5 and the output shaft 7 becomes relatively small.

The output gear 7a and the driven gear 63 are attached to the output shaft 7 so as to rotate integrally. The output gear 7a meshes with the counter driven gear 8a of the counter gear mechanism 8 which is a reduction mechanism. The counter drive gear 8b of the counter gear mechanism 8 meshes with the ring gear 9a of the differential gear 9. The left and right drive wheels 11 and 11 are connected to the differential gear 9 via the left and right drive shafts 10 and 10.

The gear train 6 includes a drive gear 61 that rotates integrally with the sun gear 4S of the forward / backward switching mechanism 4, a counter gear mechanism 62, and a driven gear 63 that rotates integrally with the output shaft 7. The gear train 6 is a reduction mechanism, and the gear ratio (gear ratio) of the gear train 6 is set to a predetermined value larger than the maximum gear ratio γmax of the CVT 5. The vehicle Ve is configured to be able to transmit torque from the engine 1 to the drive wheels 11 via the gear train 6 at the time of starting. The gear train 6 functions as, for example, a starting gear.

The drive gear 61 meshes with the counter driven gear 62a of the counter gear mechanism 62. The counter gear mechanism 62 includes a counter driven gear 62a, a counter shaft 62b, and a counter drive gear 62c that meshes with the driven gear 63. A counter driven gear 62a is attached to the counter shaft 62b so as to rotate integrally. The counter shaft 62b is arranged in parallel with the input shaft 3 and the output shaft 7. The counter drive gear 62c is configured to be rotatable relative to the counter shaft 62b.

Further, a meshing type engaging device (hereinafter referred to as a dog clutch) Sc1 that selectively and integrally rotates the counter shaft 62b and the counter drive gear 62c is provided. The dog clutch Sc1 includes a pair of meshing engaging elements 64a and 64b and a sleeve 64c that can be moved in the axial direction. The first engaging element 64a is a hub spline-fitted to the counter shaft 62b. The first engaging element 64a and the counter shaft 62b rotate integrally. The second engaging element 64b is connected to the counter drive gear 62c so as to rotate integrally. That is, the second engaging element 64b rotates relative to the counter shaft 62b. The spline teeth formed on the inner peripheral surface of the sleeve 64c mesh with the spline teeth formed on the outer peripheral surfaces of the engaging elements 64a and 64b, so that the dog clutch Sc1 is in an engaged state. By engaging the dog clutch Sc1, the drive gear 61 and the driven gear 63 are connected so as to be able to transmit torque. When the engagement between the second engaging element 64b and the sleeve 64c is released, the dog clutch Sc1 is released. By releasing the dog clutch Sc1, the torque cannot be transmitted between the drive gear 61 and the driven gear 63. Further, the dog clutch Sc1 is a hydraulic type, and the sleeve 64c is moved in the axial direction by a hydraulic actuator.

The power transmission device 100 further includes a gear ratio control unit 101 that controls a forward / backward switching mechanism 4, a CVT 5, and a gear train 6, and an engine control unit 102 that controls the engine 1. The gear ratio control unit 101 and the engine control unit 102 are connected by communication, and various types of information can be transmitted. The gear ratio control unit 101 and the engine control unit 102 may, for example, cause a processing device such as a CPU (Central Processing Unit) to execute a program, that is, may be realized by software, or may be realized by software or hardware such as an IC (Integrated Circuit). It may be realized by wear, or it may be realized by using software and hardware together.

The gear ratio control unit 101 has a selection control unit 101a and a CVT control unit 101b. The selection control unit 101a selects a power transmission path by engaging and disengaging the first clutch C1, the second clutch C2, and the brake B1, or switches between forward and reverse. Specifically, by disengaging the first clutch C1 and the brake B1 and disengaging the second clutch C2, the power of the input shaft 3 is transmitted to the output shaft 7 via the gear train 6, and the CVT 5 Does not transmit power. This state is called a gear running mode. On the other hand, by disengaging the second clutch C2 and releasing the first clutch C1 and the brake B1, the power of the input shaft 3 is transmitted to the output shaft 7 via the CVT 5, and the power is transmitted to the gear train 6. Do not do. This state is called a belt running mode. Further, during neutral coasting, the first clutch C1, the second clutch C2, and the brake B1 are in the released state, respectively.

The CVT control unit 101b changes the V-groove width of each of the pulleys 51 and 52 by hydraulically operating the primary pressure cylinder 51c and the secondary pressure cylinder 52c, and continuously changes the gear ratio γ of the CVT 5. In FIG. 1, the connection line between the gear ratio control unit 101 and the control target thereof is omitted so as not to be complicated.

The engine control unit 102 is a part that controls the output of the engine 1 by operating the throttle opening degree, the fuel injection amount, and the ignition timing according to the depression amount of the accelerator pedal (not shown). The engine control unit 102 further includes a torque determination unit 102a for determining the torque applied to the input shaft 3, and a torque suppression unit 102b for suppressing the torque applied to the input shaft 3.

The torque determination unit 102a determines the torque output by the engine 1 at that time from the fuel injection amount, the engine speed Ne, and the like. The torque suppressing unit 102b suppresses the torque based on the traveling mode supplied from the selection control unit 101a. Torque suppression is performed, for example, by manipulating the throttle opening, fuel injection amount, and ignition timing.

Next, the control procedure performed in the power transmission device 100 configured as described above will be described with reference to FIG. This control procedure is mainly executed by the torque determination unit 102a.

First, in step S1, the traveling state at that time is determined. The determination of the traveling state is performed based on the information supplied from the selection control unit 101a. When the traveling state at that time is in the gear traveling mode, the process proceeds to step S2, and when the traveling state is in the belt traveling mode, the process proceeds to step S3.

In step S2, the torque down control execution determination is performed according to the gear traveling mode. That is, the torque calculated by the torque determination unit 102a is compared with the first threshold value for protecting the gear train 6, and if the calculated torque is larger than the first threshold value, the process proceeds to step S4 and the calculation is performed. If the torque is equal to or less than the first threshold value, the process proceeds to step S5. Since the gear train 6 has a simple structure mainly composed of gears, it has high mechanical strength, and the first threshold value is set to a relatively large value.

In step S4, the torque down request amount is set to map1 corresponding to the first threshold value, and a predetermined torque suppression is performed.

Further, in step S5, since it is not necessary to suppress the torque, the torque down request amount is set as an invalid value.

On the other hand, in step S3, the torque down control execution determination is performed according to the belt traveling mode. That is, the torque calculated by the torque determination unit 102a is compared with the second threshold value for protecting the CVT 5, and if the calculated torque is larger than the second threshold value, the process proceeds to step S6, and the calculated torque is calculated. If it is equal to or less than the second threshold value, the process proceeds to step S5. Since the CVT 5 has a complicated structure composed of a belt and hydraulic equipment, its mechanical strength is a little low, the second threshold value is set to a relatively small value, and the first threshold value> the second threshold value. .. These first thresholds and second thresholds correspond to the amount of torque suppression.

In step S6, the torque down request amount is set to map2 corresponding to the second threshold value, and a predetermined torque suppression is performed. After steps S4, S5, and S6, the current control shown in FIG. 2 is terminated, and the control is re-executed after a predetermined minute time.

In the power transmission device 100 configured in this way, the torque suppression amount changes by separately setting the torque down control in the gear traveling mode and the belt traveling mode, and the gear train 6 and the CVT 5 are individually and appropriately protected. be able to. That is, in the gear traveling mode, it is possible to prevent excessive torque suppression based on a relatively large first threshold value, and to secure a traveling driving force particularly in low gear. Further, in the belt traveling mode, appropriate torque suppression is performed based on a relatively small second threshold value, and each component of the CVT 5, for example, the belt 53 can be protected.

The present invention is not limited to the above-described embodiment, and it is needless to say that the present invention can be freely changed without departing from the gist of the present invention.

1 Engine 3 Input shaft 4 Forward / backward switching mechanism 5 Belt type continuously variable transmission 6 Gear train 7 Output shaft 100 Power transmission device 101 Gear ratio control unit 101a Selection control unit 101b CVT control unit 102 Engine control unit 102a Torque judgment unit 102b Torque Suppressor B1 Brake C1 1st clutch C2 2nd clutch

Claims (1)

In a power transmission device that transmits the power of the input shaft to the output shaft
A gear transmission mechanism that transmits power by meshing gears,
A belt-type continuously variable transmission that changes the speed ratio steplessly by changing the pulley groove width of the primary pulley and secondary pulley around which the belt is wound.
A selection control unit that selects either the gear transmission mechanism or the belt-type continuously variable transmission to transmit the power of the input shaft to the output shaft.
A torque suppressing unit that suppresses the torque applied to the input shaft,
Have,
The torque suppression unit is
When power is transmitted to the output shaft by the gear transmission mechanism, if it is determined that the torque applied to the input shaft is larger than the first threshold value, the torque applied to the input shaft corresponds to the first threshold value. Suppress to the amount of suppression,
When power is transmitted to the output shaft by the belt type stepless transmission, if it is determined that the torque applied to the input shaft is larger than the second threshold value smaller than the first threshold value, the input shaft is subjected to power transmission. A power transmission device characterized in that the applied torque is suppressed to an suppression amount corresponding to the second threshold value .

Images