JP7780282B2 - Vehicle control device - Google Patents

Description

The present invention relates to a vehicle control device installed in a vehicle.

Vehicles such as automobiles are equipped with continuously variable transmissions consisting of a primary pulley and a secondary pulley (see Patent Documents 1 to 3). When changing gears in this continuously variable transmission, hydraulic control is performed on the primary and secondary pulleys. This makes it possible to control the groove width of the primary and secondary pulleys and change the winding diameter of the drive chain around each pulley, allowing the continuously variable transmission to shift to a lower or higher gear.

Japanese Patent Application Publication No. 4-78371 JP 2018-54027 A JP 2020-172983 A

When controlling the gear ratio of a continuously variable transmission, it is common to use a control valve to control the supply of hydraulic oil to the primary pulley. Furthermore, by using the control valve to control the flow rate of hydraulic oil, it is possible to control the speed change speed of the continuously variable transmission. However, when wear occurs in the spool, housing, and other components that make up the control valve, the gap between the parts increases, changing the cross-sectional area of the flow path within the control valve, making it difficult to properly control the speed change speed of the continuously variable transmission. In other words, because wear in the control valve reduces the control accuracy of the continuously variable transmission, there is a need to properly determine abnormal conditions caused by control valve wear.

The object of the present invention is to appropriately determine abnormal conditions in a control valve.

In one embodiment, a vehicle control device is provided in a vehicle, the vehicle control device having a continuously variable transmission including a primary pulley with a primary oil chamber and a secondary pulley with a secondary oil chamber . The vehicle control device has an oil pump connected to the primary oil chamber and the secondary oil chamber and pressurizing hydraulic oil to the primary oil chamber and the secondary oil chamber . The vehicle control device has a control valve provided in an oil passage connecting the oil pump and the primary oil chamber and supplying hydraulic oil to the primary oil chamber when the continuously variable transmission upshifts. The vehicle control device has a control system including a processor and memory communicatively connected to each other and controlling the continuously variable transmission via the control valve . The control system sets a higher upper limit shift speed at the start of an upshift in a step shift mode in which the gear ratio of the continuously variable transmission is controlled in steps, as the gear ratio of the continuously variable transmission increases . The control system determines that the control valve is in an abnormal state when the shift speed of the continuously variable transmission exceeds the upper limit shift speed during an upshift in the step shift mode.

In one embodiment, the vehicle control device sets an upper limit shift speed based on the gear ratio of the continuously variable transmission when starting an upshift in step shift mode, which controls the gear ratio of the continuously variable transmission in stages, and determines that the control valve is in an abnormal state if the shift speed of the continuously variable transmission exceeds the upper limit shift speed during an upshift in step shift mode. This allows for appropriate determination of an abnormal state of the control valve.

1 is a diagram showing an example of the configuration of a vehicle equipped with a vehicle control device according to an embodiment of the present invention; FIG. 1 is a diagram illustrating an example of the configuration of a vehicle control device. FIG. 2 is a diagram simply illustrating the basic structure of each control unit. FIG. 4 is a diagram showing an example of a target gear position used in a step shift mode. FIG. 4 is a diagram showing an example of a target gear position set based on a vehicle speed and an accelerator opening degree. FIG. 2 is a simplified diagram showing a part of a hydraulic circuit that constitutes the valve body. FIG. 4 is a diagram illustrating the operation of an upshift valve and a downshift valve during a downshift. 10A and 10B are diagrams illustrating the operation states of an upshift valve and a downshift valve during an upshift. 4 is a flowchart showing an example of a procedure for executing valve wear determination control. FIG. 10 is a diagram showing an example of an upper limit shift speed used in valve wear determination control. 4 is a timing chart showing an example of an execution state of valve wear determination control.

Embodiments of the present invention will be described in detail below with reference to the drawings. In the following description, identical or substantially identical configurations and elements will be designated by the same reference numerals and repeated description will be omitted.

[Vehicle configuration]
Fig. 1 is a diagram showing an example of the configuration of a vehicle 11 equipped with a vehicle control device 10 according to one embodiment of the present invention. As shown in Fig. 1, the vehicle 11 is equipped with a powertrain 14 including an engine 12 and a continuously variable transmission 13. Wheels 18 are connected to an output shaft 15 of the powertrain 14 via a propeller shaft 16 and a differential mechanism 17. The powertrain 14 shown in the figure is a rear-wheel drive powertrain, but is not limited to this and may be a front-wheel drive or all-wheel drive powertrain.

Figure 2 is a diagram showing an example configuration of the vehicle control device 10. As shown in Figure 2, the powertrain 14 has a continuously variable transmission 13 consisting of a primary pulley 20, a secondary pulley 21, and a drive chain 22. The engine 12 is connected to the primary pulley 20 of the continuously variable transmission 13 via a primary shaft 23, a forward/reverse switching mechanism 24, and a torque converter 25. The wheels 18 are connected to the secondary pulley 21 of the continuously variable transmission 13 via a secondary shaft 26, an output shaft 15, a propeller shaft 16, and a differential mechanism 17. The forward/reverse switching mechanism 24, which switches the rotation direction of the primary pulley 20, is composed of a forward clutch, a reverse brake, a planetary gear train, and the like (not shown).

The primary pulley 20 of the continuously variable transmission 13 has a fixed sheave 30 fixed to the primary shaft 23 and a movable sheave 31 axially movable on the primary shaft 23. A primary oil chamber 32 is defined behind the movable sheave 31, and by controlling the hydraulic oil pressure (primary pressure) supplied to this primary oil chamber 32, the movable sheave 31 can be moved to change the groove width between the sheaves 30 and 31. Similarly, the secondary pulley 21 of the continuously variable transmission 13 has a fixed sheave 33 fixed to the secondary shaft 26 and a movable sheave 34 axially movable on the secondary shaft 26. A secondary oil chamber 35 is defined behind the movable sheave 34, and by controlling the hydraulic oil pressure (secondary pressure) supplied to this secondary oil chamber 35, the movable sheave 34 can be moved to change the groove width between the sheaves 33 and 34. In other words, by controlling the hydraulic pressure for the primary oil chamber 32 and the secondary oil chamber 35, the pulley groove width can be changed to change the winding diameter of the drive chain 22, thereby changing the speed of the continuously variable transmission 13.

The powertrain 14 is provided with a valve body 36 consisting of multiple electromagnetic valves, oil passages, etc., to control the continuously variable transmission 13, forward/reverse switching mechanism 24, etc. that make up the powertrain 14. An oil pump 37 driven by the engine 12, etc., is connected to the valve body 36. The hydraulic oil pumped from the oil pump 37 passes through the valve body 36, where its destination, pressure, etc. are controlled, and it is supplied to the continuously variable transmission 13, forward/reverse switching mechanism 24, etc. A transmission control unit 38 is connected to the valve body 36 to control the continuously variable transmission 13, etc., via the valve body 36.

The engine 12's intake manifold 40 is also provided with a throttle valve 41 that adjusts the amount of intake air. The engine 12 is also provided with an injector 42 that injects fuel into the intake port and cylinder, and an ignition device 43 consisting of an igniter, spark plugs, etc. To control the operating conditions of the engine 12, an engine control unit 44 is connected to the throttle valve 41, injector 42, ignition device 43, etc.

[Control System]
As shown in FIG. 2 , the vehicle control device 10 is provided with a control system 50 consisting of multiple electronic control units for controlling the powertrain 14 and other components. The electronic control units constituting the control system 50 include the aforementioned transmission control unit 38 and engine control unit 44, as well as a vehicle control unit 51 that outputs control signals to these control units 38 and 44. These control units 38, 44, and 51 are communicatively connected to one another via an in-vehicle network 52 such as a CAN or LIN. The vehicle control unit 51 sets operation targets for the engine 12, the continuously variable transmission 13, and other components based on input information from the various control units 38, 44, and 51 and various sensors described below. The vehicle control unit 51 then generates control signals corresponding to the operation targets for the engine 12, the continuously variable transmission 13, and other components, and outputs these control signals to the various control units 38 and 44.

Sensors connected to the vehicle control unit 51 include a vehicle speed sensor 60 that detects the vehicle speed, which is the traveling speed of the vehicle 11; an engine speed sensor 61 that detects the engine speed, which is the rotational speed of the engine 12; an accelerator sensor 62 that detects the amount of accelerator pedal operation (hereinafter referred to as accelerator opening); and a brake sensor 63 that detects the amount of brake pedal operation. Also connected to the vehicle control unit 51 are a primary speed sensor 64 that detects the rotational speed of the primary pulley 20 and a secondary speed sensor 65 that detects the rotational speed of the secondary pulley 21. A start switch 66 that is operated by the driver to start the control system 50 is also connected to the vehicle control unit 51. A display 67 that displays notification information for the driver is also connected to the vehicle control unit 51.

Figure 3 is a simplified diagram showing the basic structure of each control unit 38, 44, 51. As shown in Figure 3, each control unit 38, 44, 51 has a microcontroller 72 incorporating a processor 70, memory 71, and the like. A predetermined program is stored in the memory 71, and the processor 70 executes the program's instruction set. The processor 70 and memory 71 are connected to each other so that they can communicate with each other. In the example shown, one processor 70 and one memory 71 are incorporated into the microcontroller 72, but this is not limited to this; multiple processors 70 may be incorporated into the microcontroller 72, and multiple memories 71 may be incorporated into the microcontroller 72.

Each control unit 38, 44, 51 is also equipped with an input conversion circuit 73, a drive circuit 74, a communication circuit 75, an external memory 76, a power supply circuit 77, and other components. The input conversion circuit 73 converts signals input from various sensors into signals that can be input to the microcontroller 72. The drive circuit 74 generates drive signals for actuators such as the valve body 36 based on signals output from the microcontroller 72. The communication circuit 75 converts signals output from the microcontroller 72 into communication signals directed to other control units. The communication circuit 75 also converts communication signals received from other control units into signals that can be input to the microcontroller 72. The power supply circuit 77 supplies a stable power supply voltage to the microcontroller 72, input conversion circuit 73, drive circuit 74, communication circuit 75, external memory 76, and other components. The external memory 76, such as a non-volatile memory, stores data that should be retained even when power is off.

[Step shift mode]
As an example of a control mode for shifting the continuously variable transmission 13, a step shift mode in which the gear ratio is controlled in stages will be described. FIG. 4 is a diagram showing an example of a target gear used in the step shift mode, and FIG. 5 is a diagram showing an example of a target gear set based on the vehicle speed and the accelerator pedal position. Also, the characteristic line Low shown in FIG. 4 is a line indicating the maximum low-side gear ratio that the continuously variable transmission 13 can control, and the characteristic line High is a line indicating the minimum high-side gear ratio that the continuously variable transmission 13 can control. The gear ratio is the ratio (Np/Ns) of the rotational speed of the primary pulley 20 (primary rotational speed Np) to the rotational speed of the secondary pulley 21 (secondary rotational speed Ns). Therefore, a larger value of the gear ratio indicates a lower gear ratio, and a smaller value of the gear ratio indicates a higher gear ratio.

As shown in FIG. 4, in the step shift mode, which controls the gear ratio in stages, multiple fixed gear ratios R1 to R6 are set as examples of target gear ratios, or pseudo-target gears, of the continuously variable transmission 13. Also, as shown in FIG. 5, the control system 50 sets the target gear in the step shift mode based on the vehicle speed and accelerator pedal position. That is, the control system 50 sets a higher target gear as the vehicle speed increases, and a lower target gear as the vehicle speed decreases. Also, the control system 50 sets a higher target gear as the accelerator pedal position decreases, and a lower target gear as the accelerator pedal position increases. Once the target gear is set based on the vehicle speed and accelerator pedal position as described above, the continuously variable transmission 13 upshifts or downshifts toward this target gear. In step shift mode, the target gear position can be changed not only automatically based on the vehicle speed and accelerator pedal position, but also manually by the driver, such as by operating the shift lever or paddles.

[Valve body]
Next, the valve body 36 that controls the supply of hydraulic oil to the primary pulley 20 and the secondary pulley 21 will be described. FIG. 6 is a simplified diagram showing a portion of the hydraulic circuit that constitutes the valve body 36. As shown in FIG. 6, an oil pump 37, such as a trochoid pump or a gear pump, is connected to the valve body 36. The oil pump 37, driven by the engine 12 or the like, draws hydraulic oil stored in an oil pan 80 and pumps the hydraulic oil toward the primary pulley 20 and the secondary pulley 21. A line pressure path 81 is connected to the discharge port of this oil pump 37, and a line pressure control valve 82 that adjusts the line pressure PL of the base hydraulic pressure is connected to the line pressure path 81. The line pressure path 81, through which hydraulic oil adjusted to the line pressure PL flows, branches into a branch oil path 83 leading to the primary pulley 20 and a branch oil path 84 leading to the secondary pulley 21.

One branch oil passage 83 branching from the line pressure passage 81 is connected to the primary oil chamber 32 of the primary pulley 20 via an upshift valve (control valve) 85 and primary oil passages 86 and 87. In this way, the oil pump 37 and primary oil chamber 32 are connected via an oil passage 88 consisting of the line pressure passage 81, branch oil passage 83, and primary oil passages 86 and 87, and an upshift valve 85 is provided in this oil passage 88. Furthermore, a downshift valve 90 is connected to the primary oil chamber 32 of the primary pulley 20 via primary oil passages 87 and 89. Furthermore, the other branch oil passage 84 branching from the line pressure passage 81 is connected to the secondary oil chamber 35 of the secondary pulley 21 via a secondary control valve 91 and a secondary oil passage 92.

The illustrated line pressure control valve 82, secondary control valve 91, upshift valve 85, and downshift valve 90 are pilot-operated valves whose operating states are controlled by pilot fluid. Pilot pressure P1 is supplied to the line pressure control valve 82 from a solenoid valve 82a, and the line pressure control valve 82 adjusts line pressure PL according to the magnitude of pilot pressure P1. Pilot pressure P2 is supplied to the secondary control valve 91 from a solenoid valve 91a, and the secondary control valve 91 adjusts secondary pressure according to the magnitude of pilot pressure P2. Pilot pressure P3 is supplied to the upshift valve 85 from a solenoid valve 85a, and the upshift valve 85 adjusts the flow rate to the primary oil chamber 32 during upshifts according to the magnitude of pilot pressure P3. Meanwhile, pilot pressure P4 is supplied to the downshift valve 90 from a solenoid valve 90a, and the downshift valve 90 adjusts the flow rate from the primary oil chamber 32 during downshifts according to the magnitude of pilot pressure P4.

The upshift valve 85 has a housing 100 and a spool 101 movably accommodated therein. The housing 100 of the upshift valve 85 is formed with an input port 102 and an output port 103. A branch oil passage 83, through which hydraulic oil adjusted to line pressure PL flows, is connected to the input port 102 of the housing 100, and a primary oil passage 86, which communicates with the primary oil chamber 32, is connected to the output port 103 of the housing 100. In addition, to operate the spool 101 of the upshift valve 85, a spring member 104 is attached to one end of the spool 101, and a pilot pressure chamber 105 is defined at the other end of the spool 101. A pilot port 106, which communicates with the pilot pressure chamber 105, is formed in the housing 100, and a pilot pressure passage 107 is connected to the pilot port 106. A solenoid valve 85a controlled by the transmission control unit 38 is connected to this pilot pressure path 107, and pilot pressure P3 regulated by the solenoid valve 85a is supplied to the pilot pressure chamber 105.

The downshift valve 90 has a housing 110 and a spool 111 movably housed therein. The housing 110 of the downshift valve 90 is formed with an input port 112 and an exhaust port 113. The input port 112 of the housing 110 is connected to the primary oil passage 89, which communicates with the primary oil chamber 32, and the exhaust port 113 of the housing 110 is connected to the exhaust oil passage 118, which leads to the oil pan 80. In addition, to operate the spool 111 of the downshift valve 90, a spring member 114 is attached to one end of the spool 111, and a pilot pressure chamber 115 is defined at the other end of the spool 111. The housing 110 is formed with a pilot port 116, which communicates with the pilot pressure chamber 115, and the pilot port 116 is connected to a pilot pressure passage 117. A solenoid valve 90a controlled by the transmission control unit 38 is connected to this pilot pressure path 117, and pilot pressure P4 regulated by the solenoid valve 90a is supplied to the pilot pressure chamber 115.

The secondary pressure regulated by the secondary control valve 91, i.e., the secondary pressure supplied to the secondary oil chamber 35, is controlled based on the target gear position, input torque, etc., in order to prevent slippage of the drive chain 22. Furthermore, the primary pressure regulated by the upshift valve 85 and downshift valve 90, i.e., the primary pressure supplied to the primary oil chamber 32, is controlled based on the target gear position, secondary pressure, etc., in order to control the gear ratio of the continuously variable transmission 13. Furthermore, the valve body 36 is provided with multiple pressure sensors (not shown), which detect the line pressure, primary pressure, secondary pressure, etc.

[Downshift]
FIG. 7 shows the operation of the upshift valve 85 and the downshift valve 90 during a downshift. As shown in FIG. 7 , during a downshift, the supply of pilot pressure P3 from the electromagnetic valve 85a is shut off, causing the spool 101 of the upshift valve 85 to move in the direction of arrow A1 due to spring force. In other words, the input port 102 and output port 103 of the upshift valve 85 are shut off from each other, and the upshift valve 85 is kept in a shut-off state with no hydraulic oil supplied. During a downshift, pilot pressure P4 is increased by the electromagnetic valve 90a, causing the spool 111 of the downshift valve 90 to move in the direction of arrow B1 against the spring force. This connects the input port 112 and the discharge port 113 of the downshift valve 90 to each other, allowing hydraulic oil in the primary oil chamber 32 to be discharged from the input port 112 through the discharge port 113, as shown by arrow FL1.

That is, as shown by arrow X1 in FIG. 6 , hydraulic oil is discharged from the primary oil chamber 32 via the downshift valve 90, reducing the primary pressure in the primary oil chamber 32, causing the movable sheave 31 of the primary pulley 20 to move away from the fixed sheave 30. Furthermore, as the winding diameter of the drive chain 22 around the primary pulley 20 decreases, the movable sheave 34 of the secondary pulley 21 moves closer to the fixed sheave 33, increasing the winding diameter of the drive chain 22 around the secondary pulley 21. In this way, hydraulic oil is discharged from the primary oil chamber 32 via the downshift valve 90, reducing the primary pressure in the primary oil chamber 32. This reduces the winding diameter of the drive chain 22 around the primary pulley 20, allowing the gear ratio of the continuously variable transmission 13 to be shifted to a lower gear (low side).

As shown in FIG. 7 , a tapered notch 120 is formed on the outer peripheral surface of the valve element 119 provided on the spool 111. In other words, when the input port 112 and the exhaust port 113 of the downshift valve 90 are connected to each other, the input port 112 and the exhaust port 113 are connected to each other via the notch 120 on the spool 111. Because the notch 109, which functions as this connecting flow path, is tapered, the cross-sectional area of the flow path connecting the input port 112 and the exhaust port 113 can be adjusted by adjusting the stopping position of the spool 111 based on the magnitude of the pilot pressure P4. In other words, by adjusting the stopping position of the spool 111 based on the pilot pressure P4, the flow rate of hydraulic oil flowing from the input port 112 to the exhaust port 113 can be controlled, thereby controlling the gear shift speed during downshifts.

[Upshift]
FIG. 8 shows the operating conditions of the upshift valve 85 and the downshift valve 90 during an upshift. As shown in FIG. 8 , during an upshift, the supply of pilot pressure P4 from the electromagnetic valve 90a is shut off, causing the spool 111 of the downshift valve 90 to move in the direction of arrow B2 due to spring force. In other words, the input port 112 and the discharge port 113 of the downshift valve 90 are shut off from each other, and the downshift valve 90 is kept in a shut-off state in which no hydraulic oil is discharged. During an upshift, the pilot pressure P3 is increased by the electromagnetic valve 85a, causing the spool 101 of the upshift valve 85 to move in the direction of arrow A2 against the spring force. This allows the input port 102 and the output port 103 of the upshift valve 85 to communicate with each other, allowing hydraulic oil from the branch oil passage 83 to be supplied from the input port 102 to the output port 103, as shown by arrow FL2.

That is, as shown by arrow X2 in FIG. 6 , hydraulic oil is supplied from the upshift valve 85 to the primary oil chamber 32, increasing the primary pressure in the primary oil chamber 32, causing the movable sheave 31 of the primary pulley 20 to move closer to the fixed sheave 30. Furthermore, as the winding diameter of the drive chain 22 around the primary pulley 20 increases, the movable sheave 34 of the secondary pulley 21 moves away from the fixed sheave 33, reducing the winding diameter of the drive chain 22 around the secondary pulley 21. In this way, hydraulic oil is supplied from the upshift valve 85 to the primary oil chamber 32, increasing the primary pressure in the primary oil chamber 32. This allows the winding diameter of the drive chain 22 around the primary pulley 20 to increase, changing the gear ratio of the continuously variable transmission 13 to a higher gear (high side).

As shown in FIG. 8 , a tapered notch 109 is formed on the outer peripheral surface of the valve element 108 of the spool 101. When the input port 102 and output port 103 of the upshift valve 85 are connected to each other, the input port 102 and output port 103 communicate with each other via the notch 109 of the spool 101. Because the notch 109, which functions as a communication flow path, is tapered, the cross-sectional area of the flow path connecting the input port 102 and output port 103 can be adjusted by adjusting the stopping position of the spool 101 based on the magnitude of the pilot pressure P3. In other words, by adjusting the stopping position of the spool 101 based on the pilot pressure P3, the flow rate of hydraulic oil flowing from the input port 102 to the output port 103 can be controlled, thereby controlling the shift speed during an upshift.

[Upshift valve wear]
As described above, when upshifting the continuously variable transmission 13, the flow rate of hydraulic oil flowing from the input port 102 to the output port 103 of the upshift valve 85 is controlled by controlling the pilot pressure P3 to adjust the stop position of the spool 101. This makes it possible to control the speed at which the continuously variable transmission 13 is upshifted, and to control the continuously variable transmission 13 at an appropriate speed in accordance with the engine output, etc. If an upshift is performed in the step shift mode, the speed is significantly higher than in a continuously variable shift mode or the like in which the gear ratio is changed continuously, and this increases the load on the upshift valve 85, which could result in wear on the housing 100, etc.

In other words, when an upshift is performed in step shift mode, the flow rate of hydraulic oil passing through the upshift valve 85 is high, and the spool 101 is pushed radially by the hydraulic oil flowing in at high speed from the input port 102. This causes the spool 101 to be pressed strongly against the inner surface of the housing 100, potentially causing wear on the housing 100 and spool 101. If the housing 100 and spool 101 are worn down by an upshift in step shift mode, it becomes difficult to control the flow rate of hydraulic oil from the input port 102 to the output port 103, making it difficult to accurately control the shift speed during an upshift. Therefore, the control system 50 executes valve wear determination control, described below, to determine the wear state of the upshift valve 85 and to perform protection processing to protect the upshift valve 85 from excessive wear.

[Valve wear determination control: flowchart]
The valve wear determination control executed by the control system 50 will now be described. Fig. 9 is a flowchart showing an example of the execution procedure for the valve wear determination control, and Fig. 10 is a diagram showing an example of the upper limit shift speed XS used in the valve wear determination control. Note that each step shown in the flowchart in Fig. 9 represents processing executed by one or more processors 70 constituting the control system 50. The valve wear determination control shown in Fig. 9 is control that is executed by the control system 50 at predetermined intervals after the driver operates the start switch 66 and the control system 50, which is composed of the vehicle control unit 51 and the like, is started up.

As shown in FIG. 9 , in step S10, it is determined whether an upshift has been initiated in step shift mode. If it is determined in step S10 that an upshift has been initiated in step shift mode, the process proceeds to step S11, where the gear position at the start of the upshift (hereinafter referred to as the upshift gear position) is read. In the following step S12, the upper limit shift speed XS allowed during an upshift is set based on the upshift gear position. In other words, in step S12, the upper limit shift speed XS allowed during an upshift is set based on the gear ratio of the continuously variable transmission 13 at the start of the upshift.

As shown in Figure 10, the upper limit shifting speed XS is set higher as the upshift gear becomes lower. For example, when the upshift gear is second gear (R2), that is, when upshifting from second gear to third gear (R2 → R3), "Xs2" is set as the upper limit shifting speed XS. Also, when the upshift gear is first gear (R1), that is, when upshifting from first gear to second gear (R1 → R2), "Xs1", which is higher than the aforementioned "Xs2", is set as the upper limit shifting speed XS. In this way, the lower the upshift gear is, the higher the upper limit shifting speed XS allowed during an upshift is set.

As described above, once the upper limit shifting speed XS is set in step S12, the process proceeds to step S13, where the shifting speed Ss of the continuously variable transmission 13 is calculated during the upshift. In step S13, the shifting speed Ss of the continuously variable transmission 13 is calculated based on a predetermined calculation period (e.g., 50 msec) and the amount of change in the gear ratio during this calculation period. Once the shifting speed Ss has been calculated in this manner, the process proceeds to step S14, where it is determined whether the shifting speed Ss exceeds the upper limit shifting speed XS. If it is determined in step S14 that the shifting speed Ss is equal to or less than the upper limit shifting speed XS, the upshift valve 85 is functioning normally, and the process proceeds to step S15, where it is determined whether the upshift is complete. If it is determined in step S15 that the upshift is not complete, the process returns to step S13, where the shifting speed Ss during the upshift is calculated and it is determined whether the shifting speed Ss exceeds the upper limit shifting speed XS.

If step S15 determines that the upshift is complete, that is, if the shift speed Ss of the continuously variable transmission 13 is equal to or less than the upper limit shift speed XS from the start to the completion of the upshift, the process proceeds to step S16, where it is determined that the upshift valve 85 is in a normal state and the routine is terminated. In other words, a situation in which the shift speed Ss during the upshift is equal to or less than the upper limit shift speed XS means that the flow rate of hydraulic oil supplied from the upshift valve 85 to the primary oil chamber 32 is appropriate. In other words, a situation in which the shift speed Ss during the upshift is equal to or less than the upper limit shift speed XS means that the flow rate of hydraulic oil passing through the upshift valve 85 is appropriately throttled, and there is no excessive wear on the housing 100, spool 101, etc. Therefore, if the shift speed Ss of the continuously variable transmission 13 is equal to or less than the upper limit shift speed XS from the start to the completion of the upshift, the upshift valve 85 is determined to be in a normal state and the routine is terminated.

On the other hand, if it is determined in step S14 that the shift speed Ss during an upshift exceeds the upper limit shift speed XS, the process proceeds to step S17, where it is determined that the upshift valve 85 is in an abnormal state. In other words, a situation in which the shift speed Ss during an upshift exceeds the upper limit shift speed XS means that hydraulic oil is being supplied from the upshift valve 85 to the primary oil chamber 32 at an excessive flow rate. In other words, a situation in which the shift speed Ss during an upshift exceeds the upper limit shift speed XS means that the flow rate of hydraulic oil passing through the upshift valve 85 is not being appropriately throttled, and this is considered to be a situation in which wear on the housing 100, spool 101, etc. is progressing. Therefore, if the shift speed Ss exceeds the upper limit shift speed XS, it is determined that wear on the housing 100, spool 101, etc. is progressing, and the upshift valve 85 is in an abnormal state.

If step S17 determines that the upshift valve 85 is in an abnormal state, the process proceeds to step S18, where a process is executed to reduce the shift speed during upshifts as a protective process to protect the upshift valve 85. In this shift speed reduction process, a new target shift speed S2 is set as the target shift speed during upshifts, which is lower than the target shift speed S1 set when the valve is normal. This makes it possible to reduce the shift speed when performing subsequent upshifts in step shift mode, reducing the load on the upshift valve 85 and suppressing wear. Note that when setting a new target shift speed S2 lower than the target shift speed S1, the target shift time from the start to the completion of the upshift may be set longer. In other words, a new target shift speed S2 lower than the target shift speed S1 may be set by setting a new target shift time longer than the target shift time corresponding to the target shift speed S1.

Furthermore, if it is determined in step S17 that the upshift valve 85 is in an abnormal state, the process proceeds to step S19, where a protective process for protecting the upshift valve 85 is executed by notifying the driver of the abnormal state of the upshift valve 85. In step S19, for example, a warning light indicating an abnormality in the continuously variable transmission 13 is illuminated, and a message urging the driver to take the vehicle to a repair shop or the like is displayed on the display 67. In this way, by urging the driver to inspect and repair the upshift valve 85, failure of the upshift valve 85 can be avoided, and the shifting quality of the continuously variable transmission 13 can be maintained appropriately over a long period of time.

[Valve wear judgment control: timing chart]
Fig. 11 is a timing chart showing an example of the execution status of the valve wear determination control. Fig. 11 shows a situation in which an upshift is performed from first gear R1 to second gear R2 in the step shift mode. In Fig. 11, the gear ratio α1 and the shift speed α2 shown by the solid lines correspond to each other, and the gear ratio β1 and the shift speed β2 shown by the dashed lines correspond to each other.

As shown at time t1 in Figure 11, when an upshift in step shift mode is initiated, the upper limit shift speed Xs1 allowed during the upshift is set based on the gear position R1 at the start of the upshift. Then, if the shift speed α2 is equal to or less than the upper limit shift speed Xs1 as shown by the solid line from time t1 to time t2, that is, from the start to completion of the upshift, the upshift valve 85 is determined to be in a normal state. In other words, if the shift speed α2 is equal to or less than the upper limit shift speed Xs1, the upshift valve 85 is sufficiently restricting the flow rate of hydraulic oil, and therefore the upshift valve 85 is determined to be in a normal state. The shift speed α2 during the upshift is controlled toward the target shift speed S1, which is set when the valve is normal.

On the other hand, as shown by the dashed line, when the shift speed β2 during an upshift exceeds the upper limit shift speed Xs1 (symbol a10), the upshift valve 85 is not sufficiently restricting the flow rate of hydraulic fluid, and the upshift valve 85 is determined to be in an abnormal state (symbol b10). In this way, when the upshift valve 85 is determined to be in an abnormal state, a new target shift speed S2 lower than the previous target shift speed S1 is set as the target shift speed for the upshift. This allows the shift speed for subsequent upshifts to be lowered, reducing the load on the upshift valve 85 and suppressing wear. Note that the target shift speeds S1 and S2 may be set differently for each gear, or a common target shift speed S1 and S2 may be set for all gears.

As explained above, the control system 50 sets the upper limit shift speed XS based on the upshift gear when an upshift in step shift mode is initiated. Furthermore, if the shift speed Ss of the continuously variable transmission 13 exceeds the upper limit shift speed XS during an upshift in step shift mode, the control system 50 determines that the upshift valve 85 is in an abnormal state. This allows for appropriate determination of an abnormality due to wear in the upshift valve 85. Furthermore, rather than using a fixed value as the upper limit shift speed XS, the control system 50 sets the upper limit shift speed XS based on the gear ratio of the continuously variable transmission 13. In other words, the control system 50 sets the upper limit shift speed XS higher the lower the upshift gear. In this way, by varying the upper limit shift speed XS according to the gear ratio of the continuously variable transmission 13, it is possible to more appropriately determine whether the upshift valve 85 is in an abnormal state.

Here, a situation in which the upshift gear is in a low gear means that a large torque capacity is required of the continuously variable transmission 13, and the line pressure PL of the hydraulic circuit is adjusted high. In other words, even if the same wear occurs in the upshift valve 85, when the upshift gear is in a low gear, the line pressure PL is higher than when the upshift gear is in a high gear, and therefore the flow rate of hydraulic oil passing through the upshift valve 85 is likely to be greater. In other words, when the upshift gear is in a low gear, the shift speed Ss of the continuously variable transmission 13 is likely to be higher than when the upshift gear is in a high gear.

For this reason, if a fixed value were used as the upper limit shifting speed XS, it would be difficult to appropriately set the upper limit shifting speed XS. In other words, if the value of the upper limit shifting speed XS were set to correspond to a high gear, when the upshift gear is a low gear, the shifting speed Ss would likely exceed the upper limit shifting speed XS, which could result in an erroneous determination that the upshift valve 85 is abnormal. On the other hand, if the value of the upper limit shifting speed XS was set to correspond to a low gear, when the upshift gear is a high gear, the shifting speed Ss would unlikely exceed the upper limit shifting speed XS, which could result in an erroneous determination that the upshift valve 85 is normal. In contrast, by varying the upper limit shifting speed XS according to the gear ratio of the continuously variable transmission 13, the upper limit shifting speed XS can be appropriately set according to the upshift gear, making it possible to more appropriately determine whether the upshift valve 85 is abnormal.

The present invention is not limited to the above-described embodiment, and it goes without saying that various modifications are possible without departing from the spirit of the invention. In the above description, the control system 50 is configured using multiple control units 38, 44, and 51, but this is not limited to this. For example, the control system 50 may be configured using a single control unit. Also, in the above description, the oil pump 37 is driven by the engine 12, but this is not limited to this, and the oil pump 37 may also be driven by an electric motor.

In the above description, an upshift valve 85 that controls the supply of hydraulic oil and a downshift valve 90 that controls the discharge of hydraulic oil are connected to the primary oil chamber 32 of the primary pulley 20, but this is not limited to this. That is, a single control valve that controls the supply and discharge of hydraulic oil may be connected to the primary oil chamber 32 of the primary pulley 20. Also, in the example shown in FIG. 9, the protective process to protect the upshift valve 85 involves reducing the shift speed during upshifts and notifying the driver of an abnormal state of the upshift valve 85, but this is not limited to this. For example, the protective process to protect the upshift valve 85 may involve only reducing the shift speed during upshifts, or only notifying the driver of an abnormal state of the upshift valve 85.

In the above description, the step shift mode, in which the gear ratio is controlled in steps, is used as the shift mode of the continuously variable transmission 13. However, other shift modes may be used in addition to the step shift mode. For example, the continuously variable transmission 13 may use a continuously variable shift mode, in which the gear ratio is continuously controlled. When executing this continuously variable shift mode, the control system 50 references a predetermined shift characteristic map based on the accelerator pedal position and vehicle speed, and sets the target gear ratio to be used in the continuously variable shift mode. For example, if the accelerator pedal is depressed while driving, the target primary rotation speed is increased in accordance with the increasing accelerator pedal position, and the target gear ratio of the continuously variable transmission 13 is continuously controlled toward the low side. On the other hand, if the accelerator pedal is eased while driving, the target primary rotation speed is decreased in accordance with the decreasing accelerator pedal position, and the target gear ratio of the continuously variable transmission 13 is continuously controlled toward the high side.

10 Vehicle control device 11 Vehicle 13 Continuously variable transmission 20 Primary pulley 21 Secondary pulley 32 Primary oil chamber 35 Secondary oil chamber 37 Oil pump 50 Control system 70 Processor 71 Memory 85 Upshift valve (control valve)
88 Oil passage XS Upper limit shift speed Ss Shift speed S1 Target shift speed S2 Target shift speed

Claims (3)

A vehicle control device provided in a vehicle,
a continuously variable transmission having a primary pulley having a primary oil chamber and a secondary pulley having a secondary oil chamber;
an oil pump connected to the primary oil chamber and the secondary oil chamber, and configured to pump hydraulic oil to the primary oil chamber and the secondary oil chamber;
a control valve provided in an oil passage connecting the oil pump and the primary oil chamber, the control valve supplying hydraulic oil to the primary oil chamber when the continuously variable transmission is upshifting;
a control system including a processor and a memory communicatively connected to each other, the control system controlling the continuously variable transmission via the control valve;
and
the control system sets an upper limit shift speed higher as the gear ratio of the continuously variable transmission increases at the start of an upshift in a step shift mode in which the gear ratio of the continuously variable transmission is controlled in a stepwise manner;
the control system determines that the control valve is in an abnormal state when the shift speed of the continuously variable transmission exceeds the upper limit shift speed during an upshift in the step shift mode.
Vehicle control device. 2. The vehicle control device according to claim 1 ,
When the control system determines that the control valve is in an abnormal state, it sets the target shift speed for upshifting to a new target shift speed that is lower than the previous target shift speed.
Vehicle control device. 3. The vehicle control device according to claim 1,
When the control system determines that the control valve is in an abnormal state, the control system notifies a driver of the abnormal state of the control valve.
Vehicle control device.