JP6065578B2 - Control device and control method for continuously variable transmission - Google Patents

Description

  The present invention relates to a control device and a control method for a continuously variable transmission capable of steplessly shifting power transmitted from a prime mover to a drive side rotary shaft and outputting the power to a driven side rotary shaft.

  Conventionally, a belt-type continuously variable transmission that can continuously change a gear ratio between an input shaft on the engine side (drive-side rotary shaft) and an output shaft on the axle side (driven-side rotary shaft) connected to the drive wheels. As a control device, in order to ensure the restarting performance from the vehicle stop state, the low return (for setting the maximum reduction ratio) to return the speed ratio of the continuously variable transmission to the maximum deceleration side immediately before the vehicle stops ( 2. Description of the Related Art A continuously variable transmission control device that performs belt return is known (see, for example, Patent Document 1). This control device temporarily increases the lift operating angle of the intake valve by the variable valve mechanism of the engine during low return to temporarily increase the engine torque, thereby reducing the input shaft rotational speed of the continuously variable transmission. By suppressing the speed ratio, the gear ratio can be made closer to the maximum deceleration side before the vehicle stops even when the vehicle suddenly stops due to sudden braking.

JP 2005-170233 A

  However, if the engine torque is temporarily increased in order to suppress a decrease in the input shaft rotation speed of the continuously variable transmission when performing the low return, the belt slips on the input shaft (drive side rotation shaft) side, There is a risk of deteriorating the durability of the belt. Further, increasing the engine torque immediately before the vehicle stops may give the driver a feeling of strangeness.

  Therefore, the main object of the present invention is to more appropriately execute belt return control for shifting the speed ratio of the continuously variable transmission to the maximum deceleration side without deteriorating the durability of the belt.

  The control device and control method for a continuously variable transmission according to the present invention employs the following means in order to achieve the main object.

A control device for a continuously variable transmission according to the present invention includes:
A first pulley provided on a drive side rotating shaft connected to a prime mover of a vehicle, a second pulley provided on a driven side rotating shaft connected to an axle of the vehicle, and the first and second pulleys. A belt to be passed, an engagement element that allows power to be transmitted from the prime mover to the axle when hydraulic pressure is supplied, and a groove width of the first and second pulleys by adjusting hydraulic pressure from an oil pump. A hydraulic pressure generating device that generates a hydraulic pressure to be changed and a hydraulic pressure to the engagement element, and steplessly shifts the power transmitted from the prime mover to the drive side rotary shaft to the driven side rotary shaft. In a control device for a continuously variable transmission capable of output,
Determining means for determining whether or not the speed ratio of the continuously variable transmission is on the deceleration side with respect to a predetermined speed ratio when the vehicle stops in a state where the shift position is a forward travel position;
An engagement element that executes pressure reduction control for reducing the hydraulic pressure supplied from the hydraulic pressure generator to the engagement element when the determination means determines that the speed ratio is not on the deceleration side with respect to the predetermined speed ratio. Decompression means;
After the pressure reduction control is started, a belt return control that executes a belt return control that increases the groove width of the first pulley and decreases the groove width of the second pulley to shift the speed ratio to the most deceleration side. Means,
Engagement element engaging means for executing engagement control for increasing the hydraulic pressure supplied from the hydraulic pressure generating device to the engagement element and engaging the engagement element after the belt return control is started;
It is characterized by providing.

  If the control device for the continuously variable transmission determines that the gear ratio of the continuously variable transmission is not on the deceleration side with respect to the predetermined gear ratio when the vehicle stops in a state where the shift position is the forward travel position, the hydraulic pressure generating device The pressure reduction control is performed to reduce the hydraulic pressure supplied to the engagement element. Further, after starting the pressure reduction control, the control device executes belt return control for increasing the groove width of the first pulley and decreasing the groove width of the second pulley to shift the speed ratio to the most deceleration side, After starting the belt return control, the engagement control for increasing the oil pressure supplied from the oil pressure generating device to the engagement element to engage the engagement element is executed. Thus, when the vehicle is stopped in a state where the shift position is the forward travel position, if the belt return control is executed after the start of the pressure reduction control for reducing the hydraulic pressure supplied from the hydraulic pressure generating device to the engagement element, the prime mover And increasing the groove width of the first pulley and decreasing the groove width of the second pulley in a state where the drive-side rotation shaft is substantially separated from the driven-side rotation shaft and the axle. Is possible. As a result, when the belt return control is executed, it is possible to prevent deterioration of the durability of the belt by preventing the belt from slipping particularly on the drive side rotating shaft side. Therefore, according to this control device, it is possible to more appropriately execute the belt return control for shifting the speed ratio of the continuously variable transmission to the maximum deceleration side without deteriorating the durability of the belt. The engagement element that enables transmission of power from the prime mover to the axle when hydraulic pressure is supplied may connect the prime mover and the drive side rotary shaft and release the connection between the two. The side rotating shaft and the axle may be connected and the connection between the two may be released.

  Further, the determination means determines whether or not the speed ratio of the continuously variable transmission is on the deceleration side with respect to a predetermined speed ratio when the vehicle stops in a state where the shift position is a forward travel position. It may be a thing. As a result, the belt return control is executed after the vehicle stops, so that the belt return control is performed as compared with the case where the belt return control is executed before the vehicle to which power is transmitted via the continuously variable transmission. Since the hydraulic pressure required for the oil pump is reduced when the operation is performed, the increase in size of the oil pump can be suppressed.

  Further, the determination means determines whether or not the speed ratio of the continuously variable transmission is on the deceleration side with respect to a predetermined speed ratio when the vehicle suddenly decelerates in a state where the shift position is a forward travel position. You may do. Thus, when the vehicle suddenly decelerates and stops, the decompression control can be started before the vehicle stops, so that the engagement element can be completely released before the vehicle stops. Belt return control and engagement control can be started at an early stage. Therefore, according to such a configuration, it is possible to promptly restart after the vehicle suddenly decelerates and stops.

  Further, the belt return control means may start the belt return control when the hydraulic pressure to the engagement element is reduced to a predetermined pressure by the pressure reduction control. Thereby, it is possible to shorten the time required from the start of the pressure reduction control to the completion of the engagement control. In this case, the time required for the engagement control can be further shortened by maintaining the hydraulic pressure to the engagement element from the stage when the hydraulic pressure to the engagement element is reduced to a predetermined pressure.

  Furthermore, the engagement element engagement means may start the engagement control before the transmission gear ratio reaches the maximum reduction ratio by the belt return control. Thereby, it is possible to further shorten the time required from the start of the pressure reduction control to the completion of the engagement control.

  The belt return control means may start the belt return control after the engagement element is completely released by the pressure reduction control, and the engagement element engagement means may be the belt return control means. The engagement control may be started after the speed change ratio reaches the maximum reduction ratio by return control. As a result, the transmission ratio of the continuously variable transmission can be shifted to the maximum reduction ratio while suppressing the occurrence of belt slipping. Such a configuration is preferably executed when stopping on a slope where the power (torque) from the prime mover may be increased while the vehicle is stopped, whereby the vehicle on the slope can be better suppressed while suppressing the occurrence of belt slippage. It is possible to make good progress again. When such belt return control is performed on an uphill road, the vehicle brake may be operated by so-called hill hold control or the like.

The control method of the continuously variable transmission according to the present invention is as follows.
A first pulley provided on a drive side rotating shaft connected to a prime mover of a vehicle, a second pulley provided on a driven side rotating shaft connected to an axle of the vehicle, and the first and second pulleys. A belt to be passed, an engagement element that allows power to be transmitted from the prime mover to the axle when hydraulic pressure is supplied, and a groove width of the first and second pulleys by adjusting hydraulic pressure from an oil pump. A hydraulic pressure generating device that generates a hydraulic pressure to be changed and a hydraulic pressure to the engagement element, and steplessly shifts the power transmitted from the prime mover to the drive side rotary shaft to the driven side rotary shaft. In the control method of the continuously variable transmission capable of output,
(A) determining whether or not the speed ratio of the continuously variable transmission is on the deceleration side with respect to a predetermined speed ratio when the vehicle stops in a state where the shift position is a forward travel position; ) Reducing the hydraulic pressure supplied from the hydraulic pressure generator to the engagement element when it is determined in step (a) that the gear ratio is not on the deceleration side of the predetermined gear ratio;
(C) after starting execution of step (b), increasing the groove width of the first pulley and decreasing the groove width of the second pulley to shift the speed ratio to the most deceleration side;
(D) After starting execution of step (c), increasing the hydraulic pressure supplied from the hydraulic pressure generator to the engagement element to engage the engagement element;
Is included.

  According to this method, it is possible to more appropriately execute the belt return control for shifting the speed ratio of the continuously variable transmission to the maximum deceleration side without deteriorating the durability of the belt.

It is a schematic block diagram of the motor vehicle 10 carrying the power transmission device 20 containing the control apparatus of the continuously variable transmission by this invention. 2 is a schematic configuration diagram of a power transmission device 20. FIG. 2 is a system diagram showing an outline of a hydraulic control device 50. FIG. 3 is a flowchart showing an example of a belt return routine executed by a speed change ECU 21. FIG. 5 is a time chart showing how the gear ratio γ, the hydraulic pressure Pc1 to the clutch C1, and the like change when the belt return routine of FIG. 4 is executed. It is a time chart which shows a mode that gear ratio γ, oil pressure Pc1 to clutch C1, etc. change when the belt return routine concerning the 1st modification is performed. It is a time chart which shows a mode that gear ratio γ, oil pressure Pc1 to clutch C1, etc. change when the belt return routine concerning the 2nd modification is performed. 6 is a time chart showing how the gear ratio γ, the hydraulic pressure Pc1 to the clutch C1, and the like change when the belt return routine according to the second modification is executed in association with rapid deceleration of the automobile 10.

  Next, the form for implementing this invention is demonstrated, referring drawings.

  FIG. 1 is a schematic configuration diagram of an automobile 10 equipped with a power transmission device 20 including a control device for a continuously variable transmission according to the present invention. An automobile 10 shown in the figure includes an engine (internal combustion engine) 12 as a prime mover that outputs power by explosion combustion of a mixture of hydrocarbon fuel such as gasoline and light oil and air, and an engine electronic for controlling the engine 12. A control unit (hereinafter referred to as “engine ECU”) 14, a brake electronic control unit (hereinafter referred to as “brake ECU”) 16 for controlling an electronically controlled hydraulic brake unit (not shown) 16, and an engine 12 are connected to the engine 12. The power transmission device 20 that transmits the power from the left and right drive wheels DW, the starter device 23 included in the power transmission device 20 and the belt-type continuously variable transmission (hereinafter referred to as “CVT”) 40. A control unit (hereinafter referred to as “shift ECU”) 21 and the like are included.

  The engine ECU 14 is configured as a microcomputer centering on a CPU (not shown). In addition to the CPU, a ROM that stores various programs, a RAM that temporarily stores data, an input / output port, and a communication port (all not shown). Etc.). As shown in FIG. 1, the engine ECU 14 has an accelerator opening Acc from an accelerator pedal position sensor 92 that detects a depression amount (operation amount) of an accelerator pedal 91, a vehicle speed V from a vehicle speed sensor 99, and rotation of a crankshaft. Signals from various sensors such as a crankshaft position sensor (not shown) for detecting the position, signals from the brake ECU 16 and the shift ECU 21 and the like are input, and the engine ECU 14 determines whether the electronically controlled throttle valve 13 or the like is shown based on these signals. Control the fuel injection valves and spark plugs that do not.

  The brake ECU 16 is also configured as a microcomputer centering on a CPU (not shown). In addition to the CPU, a ROM for storing various programs, a RAM for temporarily storing data, an input / output port and a communication port (none of which are shown). ) Etc. As shown in FIG. 1, the brake ECU 16 receives the master cylinder pressure detected by the master cylinder pressure sensor 94 when the brake pedal 93 is depressed, the vehicle speed V from the vehicle speed sensor 99, various sensors (not shown), and the like. Signals, signals from the engine ECU 14 and the shift ECU 21 and the like are input, and the brake ECU 16 controls a brake actuator (hydraulic actuator) (not shown) based on these signals.

  FIG. 2 is a schematic configuration diagram of the power transmission device 20 mounted on the automobile 10 of the present embodiment. The power transmission device 20 shown in the figure is configured as a transaxle that is connected to the engine 12 that is disposed horizontally so that the crankshaft and the left and right axles 89 connected to the drive wheels DW are substantially parallel to each other. Yes. As shown in the figure, the power transmission device 20 includes a converter housing 22a, a transaxle case 22b, and a rear cover 22c that are integrally coupled, a starting device 23 that is housed in the transmission case 22, an oil pump. 30, a forward / reverse switching mechanism 35, a CVT 40, a hydraulic control device (hydraulic pressure generating device) 50, a gear mechanism 80, a differential gear (differential mechanism) 88, and the like.

  The starting device 23 is configured as a fluid starting device with a lock-up clutch, and is housed inside the converter housing 22a. As shown in FIG. 2, the starting device 23 includes a pump impeller 24 connected to a crankshaft of the engine 12 via a front cover as an input member, a turbine runner 25 fixed to an input shaft 41 of the CVT 40, and a pump impeller. 24 and the turbine runner 25, a stator 26 that rectifies the flow of hydraulic oil (ATF) from the turbine runner 25 to the pump impeller 24, a one-way clutch 27 that restricts the rotational direction of the stator 26 in one direction, and a damper mechanism 28, a lock-up clutch 29 and the like.

  When the rotational speed difference between the pump impeller 24 and the turbine runner 25 is large, the pump impeller 24, the turbine runner 25, and the stator 26 function as a torque amplifier (torque converter) by the action of the stator 26, and the rotational speed difference therebetween is small. It will function as a fluid coupling. However, in the starting device 23, the stator 26 and the one-way clutch 27 may be omitted, and the pump impeller 24 and the turbine runner 25 may function as only a fluid coupling. The damper mechanism 28 includes, for example, an input element coupled to the lockup clutch 29, an intermediate element coupled to the input element via the plurality of first elastic bodies, and an intermediate element coupled to the plurality of second elastic bodies. And an output element fixed to the turbine hub.

  The lockup clutch 29 selectively locks up and unlocks the pump impeller 24 and the turbine runner 25, that is, the front cover and the input shaft 41 of the CVT 40 mechanically (via the damper mechanism 28). It is something to execute. When a predetermined lockup on condition is satisfied after the vehicle 10 starts, the pump impeller 24 and the turbine runner 25 are locked (directly connected) by the lockup clutch 29, and the power from the engine 12 is mechanically and directly connected to the input shaft 41. Will be transmitted. At this time, the vibration is attenuated by the damper mechanism 28 between the front cover and the input shaft 41. The lock-up clutch 29 may be configured as a hydraulic single-plate friction clutch, or may be configured as a hydraulic multi-plate friction clutch.

  The oil pump 30 is configured as a so-called gear pump including a pump assembly 33 including a pump body 31 and a pump cover 32 disposed between the starting device 23 and the forward / reverse switching mechanism 35 and an external gear 34. . The pump body 31 and the pump cover 32 are fixed to the converter housing 22a and the transaxle case 22b. The external gear 34 is connected to the pump impeller 24 via a hub. Therefore, when the external gear 34 is rotated by the power from the engine 12, the hydraulic oil (ATF) stored in the oil pan 58 is sucked by the oil pump 30 via the strainer 59 (both see FIG. 3). At the same time, the pressurized hydraulic fluid is discharged. As a result, the oil pressure required by the starting device 23, the forward / reverse switching mechanism 35, the CVT 40, etc. is generated from the oil pump 30, or the lubrication target such as predetermined parts such as the CVT 40, the one-way clutch 27, the forward / reverse switching mechanism 35 and various bearings It is possible to supply hydraulic oil as a lubricating medium.

  The forward / reverse switching mechanism 35 is accommodated in the transaxle case 22b, and includes a double pinion planetary gear mechanism 36, and a brake B1 and a clutch C1 that are hydraulic friction engagement elements. The planetary gear mechanism 36 includes a sun gear fixed to the input shaft 41 of the CVT 40, a ring gear, a pinion gear meshing with the sun gear, and a carrier supporting the pinion gear meshing with the ring gear and coupled to the primary shaft 42 of the CVT 40. The brake B1 makes the ring gear of the planetary gear mechanism 36 rotatable relative to the transaxle case 22b, and fixes the ring gear of the planetary gear mechanism 36 to the transaxle case 22b when hydraulic pressure is supplied from the hydraulic control device 50. It is something that can be done. The clutch C1 makes the carrier of the planetary gear mechanism 36 rotatable relative to the input shaft 41 (sun gear), and when the hydraulic pressure is supplied from the hydraulic control device 50, the clutch C1 causes the carrier of the planetary gear mechanism 36 to move to the input shaft 41. It can be fixed to. Thus, if the brake B1 is released and the clutch C1 is engaged, the power transmitted to the input shaft 41 can be transmitted to the primary shaft 42 of the CVT 40 as it is to advance the vehicle 10. Further, if the brake B1 is engaged and the clutch C1 is released, the rotation of the input shaft 41 is converted in the reverse direction and transmitted to the primary shaft 42 of the CVT 40, so that the automobile 10 can be moved backward. Furthermore, if the brake B1 and the clutch C1 are released, the connection between the input shaft 41 and the primary shaft 42 can be released.

  The CVT 40 includes a primary pulley 43 provided on a primary shaft 42 serving as a drive side rotation shaft, a secondary pulley 45 provided on a secondary shaft 44 serving as a driven side rotation shaft disposed in parallel with the primary shaft 42, and a primary pulley. In order to change the groove width of the belt 46, the primary cylinder 47 that is a hydraulic actuator for changing the groove width of the primary pulley 43, and the groove 46 of the secondary pulley 45. And a secondary cylinder 48 which is a hydraulic actuator. The primary pulley 43 includes a fixed sheave 43a formed integrally with the primary shaft 42, and a movable sheave 43b supported by the primary shaft 42 through a ball spline so as to be slidable in the axial direction. The fixed sheave 45a formed integrally with the secondary shaft 44 is supported by the secondary shaft 44 so as to be slidable in the axial direction via a ball spline and is urged in the axial direction by a return spring 49 which is a compression spring. It consists of a movable sheave 45b.

  The primary cylinder 47 is formed behind the movable sheave 43 b of the primary pulley 43, and the secondary cylinder 48 is formed behind the movable sheave 45 b of the secondary pulley 45. Hydraulic fluid is supplied from the hydraulic control device 50 to the primary cylinder 47 and the secondary cylinder 48 in order to change the groove width between the primary pulley 43 and the secondary pulley 45, whereby the starting device 23 and the forward / reverse switching are performed from the engine 12. The power transmitted to the primary shaft 42 via the mechanism 35 can be steplessly changed and output to the secondary shaft 44. The power output to the secondary shaft 44 is transmitted to the left and right drive wheels DW via the gear mechanism 80, the differential gear 88, and the axle 89.

  The gear mechanism 80 extends in parallel with the secondary shaft 44 and the axle 89 while being rotatably supported by the transaxle case 22b via a bearing, and is supported by the transaxle case 22b via the bearing. A counter shaft 82 supported by the counter shaft 82, a counter driven gear 83 fixed to the counter shaft 82 and meshing with the counter drive gear 81, and a drive pinion gear (final drive gear) 84 formed (or fixed) on the counter shaft 82. , And a differential ring gear (final driven gear) 85 that meshes with the drive pinion gear 84 and is connected to the differential gear 88.

  In the present embodiment, the secondary shaft 44 of the CVT 40 is rotatably supported by the hollow portion of the counter drive gear 81 via a bush (not shown). And CVT40 of this embodiment contains the dog clutch C2 as a fitting engagement element which can cancel | release the connection of the secondary shaft 44 and the counter drive gear 81, and both connection. The dog clutch C2 is, for example, a fixed-side fitting portion formed on the counter drive gear 81 and a movable-side fitting portion that is supported by the secondary shaft 44 so as to be movable in the axial direction and can be fitted to the fixed-side fitting portion. The fixed side fitting portion and the movable side fitting portion are fitted by one of the hydraulic pressure from the hydraulic control device 50 and the biasing force of the elastic body such as a spring, and the hydraulic pressure and the biasing force of the elastic body The other is configured to release the fitting between the two.

  The above-described transmission ECU 21 that controls the power transmission device 20 is also configured as a microcomputer centered on a CPU (not shown). In addition to the CPU, a ROM that stores various programs, a RAM that temporarily stores data, an RAM that stores data, An output port and a communication port (both not shown) are provided. As shown in FIG. 1, the shift ECU 21 has a shift for selecting a desired shift position from among an accelerator opening Acc from an accelerator pedal position sensor 92, a vehicle speed V from a vehicle speed sensor 99, and a plurality of shift positions. The shift position SP from the shift position sensor 96 that detects the operation position of the lever 95, the oil temperature sensor that detects the oil temperature Toil of the hydraulic oil of the hydraulic control device 50, the input rotation speed of the CVT 40 (the input shaft 41 or the primary shaft 42) Rotation speed) A signal from various sensors such as a rotation speed sensor that detects Nin, an output rotation speed of CVT 40 (rotation speed of secondary shaft 44) Nout, a signal from engine ECU 14 or brake ECU 16, and the like are input. The shift ECU 21 Starting device based on the signal 23 and CVT 40, i.e., it controls the hydraulic control device 50.

  In this embodiment, as the shift position SP of the shift lever 95, the P position corresponding to the parking range selected during parking, the R position corresponding to the reverse range for reverse travel, and the N position corresponding to the neutral neutral range. In addition to the D position corresponding to the normal drive range (D range) for forward travel, the forward travel sport that allows the driver to select an arbitrary speed from a plurality of predetermined speeds A position (S position), an upshift instruction position, and a downshift instruction position are prepared.

  FIG. 3 is a system diagram showing an outline of the hydraulic control device 50. As shown in the figure, the hydraulic control device 50 is connected to the oil pump 30 that is driven by power from the engine 12 and sucks and discharges hydraulic oil from the oil pan 58 through the strainer 59. is there. As shown in FIG. 3, the hydraulic control device 50 regulates the hydraulic oil from the oil pump 30 and generates a line pressure PL that is a source pressure of hydraulic pressure supplied to the primary cylinder 47, the secondary cylinder 48, and the like. A valve 51, a modulator valve 52 for generating a constant modulator pressure Pmod by reducing the line pressure PL, and a pressure adjusting valve for adjusting the modulator pressure Pmod from the modulator valve 52 to generate a hydraulic pressure to the brake B1 or the clutch C1. (Linear solenoid valve) 53 and the hydraulic pressure from the pressure regulating valve 53 in conjunction with the shift lever 95 are supplied to either the brake B1 or the clutch C1 according to the shift position SP, or the hydraulic pressure is supplied to both. And a manual valve 54 for shutting off.

  Further, the hydraulic control device 50 includes a first linear solenoid valve SLP, a second linear solenoid valve SLS, a primary pulley pressure control valve 55, and a secondary pulley pressure control valve 56 in order to generate a hydraulic pressure required for shifting the CVT 40. The first linear solenoid valve SLP adjusts the modulator pressure Pmod from the modulator valve 52, for example, and generates a primary solenoid pressure Pslp as a signal pressure. For example, the second linear solenoid valve SLS adjusts the modulator pressure Pmod from the modulator valve 52 to generate a secondary solenoid pressure Psls as a signal pressure. Further, the primary pulley pressure control valve 55 regulates the line pressure PL using the primary solenoid pressure Pslp from the first linear solenoid valve SLP as a signal pressure, and a primary pulley pressure (primary sheave pressure) to the primary pulley 43, that is, the primary cylinder 47. Pp is generated. The secondary pulley pressure control valve 56 regulates the line pressure PL using the secondary solenoid pressure Psls from the second linear solenoid valve SLS as a signal pressure, and a secondary pulley pressure (secondary sheave pressure) to the secondary pulley 45, that is, the secondary cylinder 48. Ps is generated.

  The pressure regulating valve 53, the first linear solenoid valve SLP, and the second linear solenoid valve SLS are all controlled by the transmission ECU 21. That is, the transmission ECU 21 controls the pressure regulating valve 53 so that the hydraulic pressure to the brake B1 and the clutch C1 becomes a target pressure corresponding to the state of the automobile 10. Further, the shift ECU 21 has a value corresponding to the target gear ratio of the CVT 40 in which the primary pulley pressure Pp from the primary pulley pressure control valve 55 is determined according to, for example, the accelerator opening Acc, the vehicle speed V, and the rotational speed Ne of the engine 12. Thus, the first linear solenoid valve SLP is controlled. Further, the transmission ECU 21 controls the second linear solenoid valve SLS so that the slip of the belt 46 of the CVT 40 is suppressed by the secondary pulley pressure Ps from the secondary pulley pressure control valve 56. In controlling these valves, the shift ECU 21 controls a drive circuit (not shown) so that a current corresponding to a hydraulic pressure command value is applied from an auxiliary battery (not shown) to the solenoid portion of each valve. In this embodiment, in order to ensure the start performance (restart performance) from the state where the automobile 10 is stopped, when the automobile 10 stops, that is, when the automobile 10 stops or when the automobile 10 decelerates rapidly. The belt returning process for setting the gear ratio of the CVT 40 to the maximum reduction ratio (for returning to the maximum reduction side) is appropriately executed.

  Next, the belt returning process in the CVT 40 will be described.

  FIG. 4 is a flowchart showing an example of a belt return routine executed by the shift ECU 21, and FIG. 5 shows a vehicle speed V, an input rotation speed Nin, and an output rotation speed Nout when the belt return routine of FIG. 6 is a time chart showing how the transmission ratio γ, the hydraulic pressure Pc1 to the clutch C1, and the input torque Tin transmitted to the primary shaft 42 of the CVT 40 change. The belt return routine shown in FIG. 4 is executed when the vehicle 10 is stopped by the driver's brake operation or when the vehicle 10 is suddenly decelerated. Here, first, the shift position SP is set to the D position or The belt return routine shown in FIG. 4 will be described as being executed when the automobile 10 is stopped by the driver's brake operation in the forward running position such as the S position.

  At the start of the belt return routine of FIG. 4, the speed change ECU 21 (CPU not shown) inputs the current speed ratio γ of the CVT 40 (step S100), and the current speed ratio γ is a predetermined reference speed ratio (predetermined speed ratio). It is determined whether it is equal to or less than γref (step S110). As the current gear ratio γ input in step S100, for example, the CVT 40 calculated from the input rotation speed Nin and the output rotation speed Nout acquired immediately before the vehicle 10 is stopped and stored in a RAM (not shown) of the transmission ECU 21 is used. Can be used. Reference speed ratio γref is set to a positive value that is relatively close to the maximum reduction ratio of CVT 40 and has a relatively large absolute value. If it is determined that the current speed ratio γ is larger than the reference speed ratio γref and is relatively close to the maximum speed reduction ratio, the speed change ECU 21 ends this routine without executing the subsequent processing. That is, when the current speed ratio γ is larger than the reference speed ratio γref, it is considered that the current speed ratio γ of the CVT 40 is sufficiently large to ensure the restart performance of the automobile 10, and the execution of the belt returning process is omitted. The

  On the other hand, when it is determined in step S110 that the current speed ratio γ is equal to or smaller than the reference speed ratio γref, the speed change ECU 21 starts the pressure reduction control (step S120) of the clutch C1 (time t0 in FIG. 5). In the pressure reduction control in step S120, the target value of the hydraulic pressure Pc1 is set in accordance with a predetermined control mode so that the hydraulic pressure Pc1 supplied from the hydraulic control device 50 to the clutch C1 of the forward / reverse switching mechanism 35 is quickly reduced. The pressure regulating valve 53 is controlled based on the target value. The pressure reduction control in step S120 is continued until it is determined in step S130 that, for example, the hydraulic pressure Pc1 to the clutch C1 is equal to or lower than a predetermined reference pressure (predetermined pressure) Pref based on the target value of the hydraulic pressure Pc1. The The reference pressure Pref as a threshold value used in step S130 is, for example, the primary pressure of the CVT 40 in a state where the engine 12 is idling and the oil pressure (hydraulic servo) of the clutch C1 is supplied with a hydraulic pressure that matches the reference pressure Pref. It is determined through experiments and analysis so as to cause the clutch C1 to slip without causing the belt 46 of the CVT 40 to slip when the groove widths of the pulley 43 and the secondary pulley 45 are changed.

  If it is determined in step S130 that the hydraulic pressure Pc1 to the clutch C1 has become equal to or lower than the reference pressure Pref, the transmission ECU 21 controls the pressure regulating valve 53 so that the hydraulic pressure Pc1 to the clutch C1 is maintained at the reference pressure Pref. Belt return control (step S140) for setting the transmission ratio of the CVT 40 to the maximum reduction ratio is started (time t1 in FIG. 5). The belt return control in step S140 increases the groove width of the primary pulley 43 by decreasing the primary pulley pressure Pp (decreases the effective radius of the primary pulley 43) and decreases the groove width of the secondary pulley 45 (secondary pulley). The effective radius of 45 is increased). In step 140 of the present embodiment, target values for the primary pulley pressure Pp and the secondary pulley pressure Ps supplied from the hydraulic control device 50 to the primary cylinder 47 and the secondary cylinder 48 according to a predetermined control mode are set, and the primary value is set. The first and second linear solenoid valves SLP and SLS are controlled so that the pulley pressure Pp and the secondary pulley pressure Ps become target values corresponding to each. The belt return control in step S140 is continued until it is determined that the predetermined time tref has elapsed since the belt return control was started in step S150. The predetermined time tref as a threshold value used in step S150 is shorter than the time required to return the transmission ratio of the CVT 40 to the maximum transmission ratio from the state in which the automobile 10 is stopped by sudden braking, for example, and the predetermined time tref has elapsed. At this point, the vehicle 10 is determined through experiments and analysis so that the starting performance of the automobile 10 can be sufficiently secured.

  If it is determined in step S150 that the predetermined time tref has elapsed since the start of the belt return control (time t2 in FIG. 5), the transmission ECU 21 continues the belt return control as described above and engages the clutch C1. Control is started (step S160). Engagement control of the clutch C1 is determined in advance so that the hydraulic pressure Pc1 supplied from the hydraulic control device 50 to the clutch C1 of the forward / reverse switching mechanism 35 increases rapidly and the clutch C1 of the forward / reverse switching mechanism 35 is engaged. The target value of the hydraulic pressure Pc1 is set according to the control mode and the pressure regulating valve 53 is controlled based on the target value. The process of step S160 is continued until it is determined in step S170 that the transmission ratio of CVT 40 is set to the maximum reduction ratio (the belt return is completed). If it is determined in step S170 that the transmission ratio of CVT 40 is set to the maximum reduction ratio (time t3 in FIG. 5), transmission ECU 21 continues only the engagement control of clutch C1 described above (step S180), and proceeds to step S190. When it is determined that the clutch C1 is completely engaged (time t4 in FIG. 5), this routine is terminated. As a result, even when the vehicle 10 stops due to sudden braking at time t0 in FIG. 5, when the vehicle 10 restarts at time t5 in FIG. It becomes possible to do.

  As described above, the shift ECU 21 that controls the CVT 40 is used when the vehicle is stopped in a state where the shift position SP is a forward travel position such as the D position, that is, the shift position SP is used for forward travel such as the D position. When it is determined that the transmission ratio of the CVT 40 is not on the decelerating side with respect to the reference transmission ratio γref when the vehicle 10 is stopped in the position state (step S110), the hydraulic control device 50 switches to the clutch C1 of the forward / reverse switching mechanism 35. Pressure reduction control (step S120) for reducing the supplied hydraulic pressure Pc1 is executed. Further, after starting the pressure reduction control, the shift ECU 21 increases the groove width of the primary pulley 43 and decreases the groove width of the secondary pulley 45 to shift the gear ratio of the CVT 40 to the most deceleration side (step S140). ) And the belt return control is started, and then the engagement control for increasing the hydraulic pressure Pc1 supplied from the hydraulic control device 50 to the clutch C1 of the forward / reverse switching mechanism 35 and engaging the clutch C1 (step S160, S180) is executed.

  Thus, when the vehicle 10 stops in a state where the shift position SP is a forward travel position such as the D position, the hydraulic pressure Pc1 supplied from the hydraulic control device 50 to the clutch C1 of the forward / reverse switching mechanism 35 is reduced. If the belt return control (step S140) is executed after the pressure reduction control (step S120) is started, the torque transmitted from the engine 12 to the primary shaft 42 is substantially reduced, that is, the engine 12 and the primary shaft 42 are substantially reduced. Thus, it is possible to increase the groove width of the primary pulley 43 and reduce the groove width of the secondary pulley 45 in a state where the pulleys are separated. As a result, when the belt return control is executed, it is possible to prevent the durability of the belt 46 from deteriorating by preventing the belt 46 from slipping particularly on the primary shaft 42 side. Therefore, in the vehicle 10 equipped with the power transmission device 20 including the CVT 40, the belt return control for shifting the speed ratio of the CVT 40 to the most deceleration side is more appropriately executed without deteriorating the durability of the belt 46 of the CVT 40. Is possible. Further, as in the above-described embodiment, the belt return control is executed after the vehicle 10 is stopped, so that the belt return control is executed as compared with the case where the belt return control is executed before the vehicle 10 where the torque is transmitted via the CVT 40. Since the hydraulic pressure required for the oil pump 30 is reduced when the return control is executed, the increase in size of the oil pump 30 can be suppressed.

  In the above embodiment, the belt return control (step S140) is started when the hydraulic pressure Pc1 to the clutch C1 of the forward / reverse switching mechanism 35 is reduced to the reference pressure Pref (step S130) by the pressure reduction control (step S120). . Thereby, it is possible to further shorten the time required from the start of the pressure reduction control (step S120) to the completion of the engagement control (steps S160 and S180). Then, as in the above-described embodiment, the engagement control executed thereafter is maintained by maintaining the hydraulic pressure Pc1 to the clutch C1 at the reference pressure Pref from the stage where the hydraulic pressure Pc1 to the clutch C1 has decreased to the reference pressure Pref. The time required for steps S160 and S180) can be further shortened.

  Furthermore, in the above-described embodiment, the stage in which it is determined that the predetermined time tref has elapsed since the start of the belt return control in Step S150, that is, the speed change ratio of the CVT 40 becomes the maximum reduction ratio by the belt return control (Step S140). Engagement control (step S160) is started before. Thereby, it is possible to further shorten the time required from the start of the pressure reduction control (step S120) to the completion of the engagement control (steps S160 and S180).

  FIG. 6 shows the vehicle speed V, the input rotation speed Nin and the output rotation speed Nout, the gear ratio γ, the hydraulic pressure Pc1 to the clutch C1, and the primary of the CVT 40 when the belt return routine according to the first modification (not shown) is executed. It is a time chart which shows a mode that the input torque Tin transmitted to the shaft 42 changes. The belt return routine according to the first modification is a process for determining whether or not the clutch C1 of the forward / reverse switching mechanism 35 is completely released by the pressure reduction control in the belt return routine shown in FIG. Corresponds to the replacement. That is, when the belt return routine according to the first modification is executed, after the pressure reduction control for the clutch C1 is started at time t0 in FIG. 6, the clutch C1 of the forward / reverse switching mechanism 35 is completely released. The belt return control as described above is started after the determination is made (time t10 in FIG. 6). As a result, although the time required from the start of the pressure reduction control to the completion of the engagement control is slightly longer, a state where torque is not transmitted from the engine 12 to the primary shaft 42, that is, the engine 12 and the primary shaft 42 are completely connected. Since the groove width of the primary pulley 43 can be increased and the groove width of the secondary pulley 45 can be decreased in the separated state, the occurrence of slippage of the belt 46 of the CVT 40 can be suppressed more favorably.

  FIG. 7 shows the vehicle speed V, the input rotation speed Nin and the output rotation speed Nout, the gear ratio γ, the hydraulic pressure Pc1 to the clutch C1, and the primary of the CVT 40 when the belt return routine according to the second modification (not shown) is executed. It is a time chart which shows a mode that the input torque Tin transmitted to the shaft 42 changes. In the belt return routine according to the second modification, in the belt return routine shown in FIG. 4, the process of step S130 is a process for determining whether or not the clutch C1 of the forward / reverse switching mechanism 35 is completely released by the pressure reduction control. At the same time, the processing in steps S150 and S160 is omitted, and the belt return control in step S140 is continued until it is determined in step S170 that the gear ratio of CVT 40 has been set to the maximum reduction ratio (belt return has been completed). It corresponds to a thing.

  That is, when the belt return routine according to the second modification is executed, after the pressure reduction control for the clutch C1 is started at time t0 in FIG. 7, the clutch C1 of the forward / reverse switching mechanism 35 is completely released. The belt return control as described above is started after the determination is made (time t100 in FIG. 7) and engaged after the gear ratio of the CVT 40 reaches the maximum reduction ratio by the belt return control (time t200 in FIG. 7). Control will be started. This makes it possible to shift the transmission ratio of the CVT 40 to the maximum reduction ratio while better suppressing the occurrence of slippage of the belt 46 of the CVT 40. The belt return routine according to the second modified embodiment is preferably executed when the vehicle 10 is stopped when the vehicle 10 is stopped, which may increase the torque from the engine 12, so that the belt of the CVT 40 can slip. The vehicle 10 can be made to recur well on the slope while being better suppressed. When such belt return control is performed on an uphill road, the electronically controlled hydraulic brake unit of the automobile 10 may be operated by so-called hill hold control or the like.

  Note that the belt return routine of FIG. 4 and the belt return routines according to the first and second modifications are performed by the driver's brake operation in the state where the shift position SP is a forward travel position such as the D position or the S position. As described above, when the vehicle 10 suddenly decelerates in a state where the shift position SP is the forward travel position, that is, the vehicle 10 suddenly decelerates due to the driver's brake operation and stops ( Is also executed (started). In FIG. 8, when the belt return routine according to the second modification described above is executed in response to the rapid deceleration of the automobile 10, the vehicle speed V, the input rotation speed Nin and the output rotation speed Nout, the transmission gear ratio γ, and the clutch C1. This shows how the oil pressure Pc1 and the input torque Tin transmitted to the primary shaft 42 of the CVT 40 change.

  In this case, the shift ECU 21 also functions as a determination unit that determines whether or not the automobile 10 is suddenly decelerated and stops. For example, a brake-on signal is transmitted from the brake ECU 16 and is detected by an acceleration sensor (G sensor) (not shown). If the vehicle 10 is suddenly decelerated and stopped by the driver's brake operation when the deceleration acceleration obtained by calculation is equal to or less than a predetermined acceleration (negative value) and the vehicle speed V is equal to or less than the predetermined vehicle speed. It can be configured to determine. Then, when the pressure reduction control is started from the time when the shift ECU 21 determines that the vehicle 10 is suddenly decelerated and stops (time t0 in FIG. 8), that is, before the vehicle 10 stops, the vehicle 10 stops as shown in FIG. The clutch C1 can be completely released by the time (see time t1000 in FIG. 8), and belt return control and engagement control can be started earlier (time t1000, t2000 in FIG. 8). As a result, it is possible to quickly restart after the vehicle 10 decelerates suddenly and stops in the example of Fig. 8 while the pressure reduction control is being executed (until the clutch C1 is completely released). For example, when the hydraulic pressure Pc1 to the clutch C1 is reduced to a predetermined pressure, the primary pulley pressure Pp is reduced to a predetermined relatively low pressure. Good. Thus, the shift speed for during rapid deceleration to return the belt 46 is accelerated, it is possible to shorten the time required for the belt return control after stopping the vehicle 10.

  Further, the belt return routine of FIG. 4 and the belt return routines according to the first and second modified modes reduce the hydraulic pressure Pc1 supplied from the hydraulic control device 50 to the clutch C1 of the forward / reverse switching mechanism 35 by the pressure reduction control. However, in these routines, the hydraulic pressure supplied from the hydraulic control device 50 to the clutch (dog clutch) C2 of the CVT 40 may be reduced by the pressure reduction control. These belt return routines also increase the groove width of the primary pulley 43 while the secondary shaft 44 and the axle 89 are substantially (or completely) separated and allow the secondary shaft 44 to rotate, and the secondary pulley 45. Therefore, it is possible to satisfactorily suppress the occurrence of slippage of the belt 46 on the primary shaft 42 side or the secondary shaft 44 side.

  Here, the correspondence between the main elements in the embodiment and the like and the main elements of the invention described in the column of means for solving the problem will be described. That is, in the above-described embodiment and the like, when the primary pulley 43 provided on the primary shaft 42, the secondary pulley 45 provided on the secondary shaft 44, the belt 46 laid over both, and the hydraulic pressure Pc1 are supplied. Clutchs C1 and C2 capable of transmitting power from the engine 12 of the automobile 10 to the axle 89, and hydraulic pressure and clutch for adjusting the hydraulic pressure from the oil pump 30 and changing the groove width of the primary pulley 43 and the secondary pulley 45 CVT 40 including a hydraulic control device 50 that generates hydraulic pressure Pc1 and the like to C1, C2, and the like, which can continuously change the power transmitted from the engine 12 to the primary shaft 42 and output it to the secondary shaft 44 is “continuously variable transmission”. 4 ”, the process of step S110 in FIG. When the vehicle 10 stops in the forward travel position such as the D position, the speed change ECU 21 that determines whether or not the speed ratio of the CVT 40 is on the deceleration side with respect to the reference speed ratio γref corresponds to “determination means”. When it is determined in step S110 that the transmission ratio of the CVT 40 is not on the deceleration side with respect to the reference transmission ratio γref, in step S120, the pressure reduction that reduces the hydraulic pressure Pc1 and the like supplied from the hydraulic control device 50 to the clutch C1 and the like. The transmission ECU 21 that executes the control corresponds to the “engagement element pressure reducing means”. After the pressure reduction control is started, the groove width of the primary pulley 43 is increased and the groove width of the secondary pulley 45 is decreased in steps S140 and S160. The speed change ECU 21 that executes the belt return control for shifting the gear ratio of the CVT 40 to the most deceleration side is Engagement control corresponding to "means" and increasing the hydraulic pressure Pc1 supplied from the hydraulic control device 50 to the clutch C1 etc. in steps S160 and S180 after the belt return control is started to engage the clutch C1. The shift ECU 21 that executes the operation corresponds to “engagement element engagement means”. However, the correspondence between the main elements in the above embodiment and the main elements of the invention described in the column of means for solving the problem is described in the column of means for the embodiment to solve the problem. Since it is an example for concretely explaining the form for carrying out the invention, the element of the invention indicated in the column of the means for solving a subject is not limited. That is, the embodiment is merely a specific example of the invention described in the means for solving the problem, and the interpretation of the invention described in the means for solving the problem is It should be done based on the description.

  Although the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments, and it goes without saying that various modifications can be made without departing from the scope of the present invention. Absent.

  The present invention can be used in the manufacturing industry of continuously variable transmissions.

  DESCRIPTION OF SYMBOLS 10 Car, 12 Engine, 13 Throttle valve, 14 Engine electronic control unit (engine ECU), 16 Brake electronic control unit (brake ECU), 20 Power transmission device, 21 Shift electronic control unit (shift ECU), 22 Transmission Case, 22a Converter housing, 22b Transaxle case, 22c Rear cover, 23 Starter, 24 Pump impeller, 25 Turbine runner, 26 Stator, 27 One-way clutch, 28 Damper mechanism, 29 Lock-up clutch, 30 Oil pump, 31 Pump body, 32 pump cover, 33 pump assembly, 34 external gear, 35 forward / reverse switching mechanism, 36 planetary gear mechanism, 40 continuously variable transmission (CVT), 41 input shaft, 4 Primary shaft, 43 Primary pulley, 43a Fixed sheave, 43b Movable sheave, 44 Secondary shaft, 45 Secondary pulley, 45a Fixed sheave, 45b Movable sheave, 46 Belt, 47 Primary cylinder, 48 Secondary cylinder, 49 Return spring, 50 Hydraulic control device , 51 Primary regulator valve, 52 Modulator valve, 53 Pressure regulating valve, 54 Manual valve, 55 Primary pulley pressure control valve, 56 Secondary pulley pressure control valve, 58 Oil pan, 59 Strainer, 80 Gear mechanism, 81 Counter drive gear, 82 Counter shaft, 82 Counter shaft, 83 Counter driven gear, 84 Drive pinion gear, 85 diff ring gear, 88 diff Rental gear, 89 axle, 91 accelerator pedal, 92 accelerator pedal position sensor, 93 brake pedal, 94 master cylinder pressure sensor, 95 shift lever, 96 shift position sensor, 99 vehicle speed sensor, B1 brake, C1 clutch, C2 dog clutch, SLP 1 Linear solenoid valve, SLS Second linear solenoid valve.

Claims (5)

A first pulley provided on a drive side rotating shaft connected to a prime mover of a vehicle, a second pulley provided on a driven side rotating shaft connected to an axle of the vehicle, and the first and second pulleys. A belt to be passed, an engagement element that allows power to be transmitted from the prime mover to the axle when hydraulic pressure is supplied, and a groove width of the first and second pulleys by adjusting hydraulic pressure from an oil pump. A hydraulic pressure generating device that generates a hydraulic pressure to be changed and a hydraulic pressure to the engagement element, and steplessly shifts the power transmitted from the prime mover to the drive side rotary shaft to the driven side rotary shaft. In a control device for a continuously variable transmission capable of output,
When the vehicle is decelerating rapidly while the shift position is the forward traveling position, the speed ratio of the continuously variable transmission and a judging means for judging whether or not the deceleration side of the predetermined gear ratio,
An engagement element that executes pressure reduction control for reducing the hydraulic pressure supplied from the hydraulic pressure generator to the engagement element when the determination means determines that the speed ratio is not on the deceleration side with respect to the predetermined speed ratio. Decompression means;
Belt return control means for executing belt return control for increasing the groove width of the first pulley and decreasing the groove width of the second pulley to shift the speed ratio to the most decelerating side after execution of the pressure reduction control; ,
Engagement element engaging means for executing engagement control for increasing the hydraulic pressure supplied from the hydraulic pressure generating device to the engagement element and engaging the engagement element after the belt return control is started;
Equipped with a,
Control device for a continuously variable transmission, wherein Rukoto reduce the hydraulic pressure supplied to the first pulley during execution of the decompression control. The control device for a continuously variable transmission according to claim 1 ,
The control device for a continuously variable transmission, wherein the belt return control means starts the belt return control when the hydraulic pressure to the engagement element is reduced to a predetermined pressure by the pressure reduction control. The control device for a continuously variable transmission according to claim 1 or 2 ,
The control device for a continuously variable transmission, wherein the engagement element engagement means starts the engagement control before the transmission gear ratio reaches a maximum reduction ratio by the belt return control. The control device for a continuously variable transmission according to claim 1 or 2 ,
The belt return control means starts the belt return control after the engagement element is completely released by the pressure reduction control,
The control device for a continuously variable transmission, wherein the engagement element engagement means starts the engagement control after the speed ratio becomes a maximum reduction ratio by the belt return control. A first pulley provided on a drive side rotating shaft connected to a prime mover of a vehicle, a second pulley provided on a driven side rotating shaft connected to an axle of the vehicle, and the first and second pulleys. A belt to be passed, an engagement element that allows power to be transmitted from the prime mover to the axle when hydraulic pressure is supplied, and a groove width of the first and second pulleys by adjusting hydraulic pressure from an oil pump. A hydraulic pressure generating device that generates a hydraulic pressure to be changed and a hydraulic pressure to the engagement element, and steplessly shifts the power transmitted from the prime mover to the drive side rotary shaft to the driven side rotary shaft. In the control method of the continuously variable transmission capable of output,
When the vehicle is decelerating rapidly in a state (a) the shift position is the forward traveling position, determining whether the transmission ratio of the continuously variable transmission is in the deceleration side of the predetermined gear ratio, (B) reducing the hydraulic pressure supplied to the engagement element from the hydraulic pressure generator when it is determined in step (a) that the gear ratio is not on the deceleration side of the predetermined gear ratio; (C) After executing step (b), increasing the groove width of the first pulley and decreasing the groove width of the second pulley to shift the speed ratio to the most deceleration side; and (d) After starting execution of step (c), increasing the hydraulic pressure supplied to the engagement element from the hydraulic pressure generating device to engage the engagement element;
Only including, a control method of a continuously variable transmission that reduces the hydraulic pressure supplied to the first pulley during the execution of step (b).

Images