Vehicle control devices

Abstract

To prevent a lock-up piston and a turbine hub from wearing against each other.SOLUTION: A vehicle control device comprises: a turbine hub which has a flange section connected to a turbine runner of a torque converter and a hub section connected to a turbine shaft; a lock-up piston which has a cylinder section which is positioned on a peripheral surface of the hub section and slidably supported and a disk section outwardly extended from the cylinder section in a radial direction; a damper mechanism which is connected to both the turbine hub and the lock-up piston; and a control system which controls an engine connected to the torque converter. The control system: calculates a PV value which is a product of sliding surface pressure between the hub section and the cylinder section and a sliding speed; and causes engine torque to change more gradually when the PV value exceeds a threshold compared to when the PV value falls below the threshold.SELECTED DRAWING: Figure 8

Description

Technical Field

[0001] The present invention relates to a vehicle control device installed in a vehicle. Background Art

[0002] A power train mounted on a vehicle is provided with an engine and a torque converter connected to the engine. The torque converter is also provided with a lock-up clutch that directly connects the input-side crankshaft and the output-side turbine shaft. Furthermore, the torque converter is provided with a damper mechanism that allows relative rotation between the crankshaft and the turbine shaft when the lock-up clutch is engaged, that is, a damper mechanism that allows relative rotation between the lock-up piston and the turbine hub (see Patent Documents 1 to 3). Prior Art Documents Patent Documents

[0003] Patent Document 1 Japanese Unexamined Patent Application Publication No. 2015-113904 Patent Document 2 Japanese Unexamined Patent Application Publication No. 2011-64291 Patent Document 3 Japanese Unexamined Patent Application Publication No. 2019-44903 Summary of the Invention Problems to be Solved by the Invention

[0004] Incidentally, when the engine torque increases or decreases while the lock-up clutch is engaged, the damper mechanism twists, causing relative rotation between the lock-up piston and the turbine hub. At this time, the contact portions between the lock-up piston and the turbine hub slide against each other, and excessive wear of these contact portions causes hydraulic oil circulation within the torque converter, which is a factor that increases the workload of the oil pump. Additionally, excessive wear of the contact portions between the lock-up piston and the turbine hub is a factor that causes poor engagement of the lock-up clutch.

[0005] The objective of this invention is to suppress wear between the lock-up piston and the turbine hub. [Means for solving the problem]

[0006] A vehicle control device according to one embodiment is a vehicle control device installed in a vehicle, comprising a turbine hub comprising a flange portion connected to the turbine runner of a torque converter and a hub portion connected to the turbine shaft. The vehicle control device has, A lock-up piston comprising a cylindrical portion slidably supported on the outer circumferential surface of the hub portion, and a disc portion extending radially outward from the cylindrical portion. The vehicle control device has, A damper mechanism connected to both the turbine hub and the lock-up piston, allowing relative rotation between the hub portion and the cylindrical portion. The vehicle control device has, A control system comprising a processor and memory connected to each other in a manner that enables communication, controls the engine connected to the torque converter. Mu Yes do. The control system operates under the condition that the lock-up piston is fastened to the crankshaft of the engine. The control system estimates the sliding surface pressure between the hub portion and the cylindrical portion such that it increases as the engine speed increases and as the engine torque increases. The control system estimates the absolute value of the sliding speed between the hub portion and the cylindrical portion such that it increases as the absolute value of the rate of change of engine torque increases, while the lock-up piston is fastened to the crankshaft of the engine. The control system estimates the sliding surface pressure between the hub portion and the cylindrical portion such that it increases as the absolute value of the rate of change of engine torque increases, while the lock-up piston is fastened to the crankshaft of the engine. Sliding surface pressure and The aforementioned Sliding speed absolute value Calculate the PV value, which is the product of the two values. The control system sets a threshold for determining wear between the hub portion and the cylindrical portion. The aforementioned PV value Up When rotating, the engine torque changes more gradually than when the PV value falls below the threshold. [Effects of the Invention]

[0007] According to one aspect of the present invention, the control system calculates a PV value, which is the product of the sliding surface pressure and sliding speed between the hub portion and the cylindrical portion, while the lock-up piston is fastened to the engine's crankshaft. When the PV value exceeds a threshold, the engine torque is changed more gradually than when the PV value falls below the threshold. This suppresses wear between the lock-up piston and the turbine hub. [Brief explanation of the drawing]

[0008] [Figure 1]1 is a diagram showing an example of a vehicle including a vehicle control device according to an embodiment of the present invention. [Figure 2] It is a diagram showing an example of a vehicle control device. [Figure 3] It is a diagram showing an example of a basic structure of a control unit. [Figure 4] It is a diagram showing a torque converter and the vicinity thereof. [Figure 5] It is a cross-sectional view showing the torque converter together with a valve body. [Figure 6] It is a diagram showing a part of a lock-up damper and a lock-up piston along the line A-A in FIG. 4. [Figure 7] It is a diagram showing an example of an operating state of the lock-up damper. [Figure 8] It is a flowchart showing an example of an execution procedure of wear suppression control. [Figure 9] It is a diagram showing an example of sliding surface pressure estimated based on engine speed and engine torque. [Figure 10] It is a cross-sectional view showing a sliding portion between a hub portion and a cylindrical portion and the vicinity thereof. [Figure 11] It is a schematic diagram showing an example of a load input to a sliding portion between a hub portion and a cylindrical portion. [Figure 12] It is a schematic diagram showing an example of a load input to a sliding portion between a hub portion and a cylindrical portion. [Figure 13] It is a diagram showing an example of a relationship between engine torque and sliding speed. [Figure 14] It is a diagram showing an example of a threshold value to be compared with a PV value. [Figure 15] It is a diagram showing an example of an execution state of torque change suppression processing. [Figure 16] It is a diagram showing another control example in the torque change suppression processing. MODE FOR CARRYING OUT THE INVENTION

[0009] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In the following description, the same or substantially the same configurations and elements are denoted by the same reference numerals, and repeated description thereof will be omitted.

[0010] [Vehicle] FIG. 1 is a diagram showing an example of a vehicle 11 including a vehicle control device 10 according to an embodiment of the present invention. As shown in FIG. 1, the vehicle 11 is equipped with a power train 14 including an engine 12 and a transmission 13. A torque converter 15 is incorporated in the transmission 13, and a speed change mechanism 16 such as an automatic transmission or a continuously variable transmission is also incorporated therein. A wheel 20 is connected to an output shaft 17 of the transmission 13 via a propeller shaft 18 and a differential mechanism 19. Although the illustrated power train 14 is a power train for rear wheel drive, the power train is not limited thereto, and may be a power train for front wheel drive or all wheel drive.

[0011] FIG. 2 is a diagram showing an example of the vehicle control device 10. As shown in FIG. 2, in order to control the torque converter 15, the speed change mechanism 16 and the like incorporated in the power train 14, the power train 14 is provided with a valve body 21 including an electromagnetic valve, an oil passage and the like. An oil pump 22 driven by the engine 12 is connected to the valve body 21. Hydraulic pressure-fed from the oil pump 22 is pressure-regulated through the valve body 21, and then supplied to the torque converter 15, the speed change mechanism 16 and the like. In order to control the torque converter 15 and the like via the valve body 21, a transmission control unit 23 is connected to the valve body 21.

[0012] Furthermore, the intake manifold 24 of the engine 12 is equipped with a throttle valve 25 for adjusting the amount of intake air. In addition, the engine 12 is equipped with injectors 26 for injecting fuel into the intake ports and cylinders, and an ignition system 27 consisting of an igniter and spark plugs. An engine control unit 28 is connected to the throttle valve 25, injectors 26, and ignition system 27, etc., in order to control engine torque and engine speed.

[0013] [Control System] As shown in Figure 2, the vehicle control device 10 is equipped with a control system 30 consisting of multiple electronic control units for controlling the powertrain 14 and the like. The electronic control units constituting the control system 30 include the aforementioned transmission control unit 23 and engine control unit 28, as well as a vehicle control unit 31 that outputs control signals to these control units 23 and 28. These control units 23, 28 and 31 are connected to each other so as to be able to communicate via an in-vehicle network 29 such as CAN. The vehicle control unit 31 sets operating targets for the engine 12, torque converter 15, etc., based on input information from various control units and various sensors described later. It then generates control signals according to the operating targets for the engine 12, torque converter 15, etc., and outputs these control signals to the engine control unit 28 and transmission control unit 23.

[0014] Sensors connected to the vehicle control unit 31 include a vehicle speed sensor 32 for detecting the vehicle speed (the speed at which the vehicle 11 travels), an accelerator sensor 33 for detecting the operation status of the accelerator pedal, and a brake sensor 34 for detecting the operation status of the brake pedal. The vehicle control unit 31 is also connected to a start switch 35, which is operated by the driver when starting the control system 30. Furthermore, sensors connected to the engine control unit 28 include a crank angle sensor 37 for detecting the rotation angle of the crankshaft 36 on the engine 12, an airflow meter 38 for detecting the intake air volume of the engine 12, a water temperature sensor 39 for detecting the coolant temperature of the engine 12, and a throttle opening sensor 40 for detecting the opening degree of the throttle valve 25. The engine control unit 28 can calculate the engine torque, which is the output torque of the crankshaft 36, and the engine speed, which is the rotational speed of the crankshaft 36, based on the detection signals from the various sensors.

[0015] Figure 3 shows an example of the basic structure of control units 23, 28, and 31. As shown in Figure 3, the electronic control units 23, 28, and 31 have a microcontroller 52 that incorporates a processor 50 and main memory (memory) 51, etc. A predetermined program is stored in the main memory 51, and the program is executed by the processor 50. The processor 50 and the main memory 51 are connected to each other so as to be able to communicate with each other. Note that the microcontroller 52 may incorporate multiple processors 50, and the microcontroller 52 may also incorporate multiple main memory 51.

[0016] Furthermore, control units 23, 28, and 31 are equipped with an input circuit 53, a drive circuit 54, a communication circuit 55, an external memory 56, and a power supply circuit 57, etc. The input circuit 53 converts signals input from various sensors into signals that can be input to the microcontroller 52. The drive circuit 54 generates drive signals for various devices such as the injector 26 mentioned above, based on signals output from the microcontroller 52. The communication circuit 55 converts signals output from the microcontroller 52 into communication signals for other control units. The communication circuit 55 also converts communication signals received from other control units into signals that can be input to the microcontroller 52. In addition, the power supply circuit 57 supplies a stable power supply voltage to the microcontroller 52, input circuit 53, drive circuit 54, communication circuit 55, and external memory 56, etc. Furthermore, the external memory 56, which consists of non-volatile memory, stores programs and various data.

[0017] [Torque converter] Figure 4 shows the torque converter 15 and its vicinity, and Figure 5 is a cross-sectional view showing the torque converter 15 together with the valve body 21. Note that Figure 5 shows a portion of the valve body 21 and a portion of the torque converter 15.

[0018] As shown in Figures 4 and 5, the torque converter 15 has a pump shell 60 connected to the engine 12. That is, the pump shell 60 is connected to the crankshaft 36 of the engine 12 via a drive plate 61. The torque converter 15 also includes a pump impeller 62 fixed to the pump shell 60 and a turbine runner 63 facing the pump impeller 62. The flange portion 65 of the turbine hub 64 is connected to the turbine runner 63, and the turbine shaft 67 is connected to the hub portion 66 of the turbine hub 64. Hydraulic fluid is supplied to the torque converter 15, and engine torque is transmitted from the pump impeller 62 to the turbine runner 63 via the hydraulic fluid. A transmission mechanism 16 is connected to the turbine shaft 67, and an oil pump 22 is connected to the pump shell 60 via a chain mechanism 68.

[0019] [Lock-up clutch] The torque converter 15 is provided with a lock-up clutch 70 that directly connects the crankshaft 36 and the turbine shaft 67. The lock-up clutch 70 has a lock-up piston 71 housed in the pump shell 60. This lock-up piston 71 faces the front cover 72 of the pump shell 60. The lock-up piston 71 also has a cylindrical portion 73 that is slidably supported on the outer circumferential surface 66a of the hub portion 66 of the turbine hub 64, and a disc portion 74 that extends radially outward from the cylindrical portion 73. By housing such a lock-up piston 71 in the pump shell 60, an apply chamber 75 and a release chamber 76 are partitioned within the pump shell 60. That is, the apply chamber 75 is partitioned on the turbine runner 63 side, and the release chamber 76 is partitioned on the front cover 72 side, with the lock-up piston 71 as the boundary.

[0020] The torque converter 15 is connected to the aforementioned valve body 21 in order to supply hydraulic fluid to the apply chamber 75 and the release chamber 76. As shown in Figure 5, the valve body 21 is provided with a clutch pressure control valve 80, a lock-up control valve 81, and a flow control valve 82. The clutch pressure control valve 80 is connected to a discharge oil passage 83 that guides the hydraulic fluid discharged from the oil pump 22. The lock-up control valve 81 is connected to a supply oil passage 84 that receives hydraulic fluid from the clutch pressure control valve 80, and to a discharge oil passage 85 that discharges hydraulic fluid via the flow control valve 82. Furthermore, the lock-up control valve 81 is connected to an apply oil passage 86 that communicates with the apply chamber 75, and to a release oil passage 87 that communicates with the release chamber 76.

[0021] When the lock-up clutch 70 is engaged, the spool valve shaft (not shown) of the lock-up control valve 81, which is an oil passage switching valve, is controlled to the engaged position. As a result, the supply oil passage 84 and the apply oil passage 86 are connected via the lock-up control valve 81, and the discharge oil passage 85 and the release oil passage 87 are connected via the lock-up control valve 81. By controlling the lock-up control valve 81 in this way, hydraulic fluid is supplied to the apply chamber 75 and discharged from the release chamber 76, as shown by the arrow FL1 in Figure 5. When the pressure in the apply chamber 75 (hereinafter referred to as the apply pressure) rises and the pressure in the release chamber 76 (hereinafter referred to as the release pressure) falls, the lock-up piston 71 moves toward the front cover 72 due to the pressure difference. As a result, the lock-up piston 71 is pressed against the front cover 72, and the lock-up clutch 70 is switched to the engaged state. In other words, when the lock-up clutch 70 is engaged, the lock-up piston 71 is engaged with the crankshaft 36 via the front cover 72.

[0022] On the other hand, when the lock-up clutch 70 is released, the spool valve shaft of the lock-up control valve 81 is controlled to the released position. As a result, the supply oil passage 84 and the release oil passage 87 are connected via the lock-up control valve 81, and the discharge oil passage 85 and the apply oil passage 86 are connected via the lock-up control valve 81. By controlling the lock-up control valve 81 in this way, as shown by the arrow FL2 in Figure 5, hydraulic fluid is supplied to the release chamber 76 and hydraulic fluid is discharged from the apply chamber 75. When the apply pressure decreases and the release pressure increases, the lock-up piston 71 moves away from the front cover 72 due to the pressure difference. As a result, the lock-up piston 71 is separated from the front cover 72, and the lock-up clutch 70 is switched to the released state. The lock-up clutch 70 can be switched according to the vehicle speed. For example, when the vehicle speed exceeds a predetermined value, the lock-up clutch 70 is switched to the engaged state, while when the vehicle speed falls below a predetermined value, the lock-up clutch 70 is switched to the released state.

[0023] [Lock-up damper] The torque converter 15 is provided with a lock-up damper (damper mechanism) 90. This lock-up damper 90 is located in the torque transmission path while the lock-up clutch is engaged. Figure 6 shows a portion of the lock-up damper 90 and lock-up piston 71 along line AA in Figure 4. As shown in Figures 4 to 6, the lock-up damper 90 has an outer plate 91 connected to the lock-up piston 71. Multiple grooves 92 are formed on the outer circumference of the outer plate 91, and multiple claws 93 are formed on the outer circumference of the lock-up piston 71. The lock-up piston 71 and the outer plate 91 are connected to each other by engaging the claws 93 of the lock-up piston 71 with the grooves 92 of the outer plate 91.

[0024] Furthermore, the lock-up damper 90 has an inner plate 94 connected to the turbine shaft 67 via a turbine hub 64. The turbine hub 64 and the inner plate 94 are connected to each other using a plurality of pin members 95. In addition, the lock-up damper 90 has a plurality of coil springs 96, 97 arranged in the circumferential direction. One end of each coil spring 96, 97 is in contact with an inner protrusion 98 of the outer plate 91, and the other end of each coil spring 96, 97 is in contact with an outer protrusion 99 of the inner plate 94. In other words, the coil springs 96, 97 are provided between the outer plate 91 and the inner plate 94.

[0025] Thus, the inner plate 94 of the lock-up damper 90 is connected to the turbine hub 64, and the outer plate 91 of the lock-up damper 90 is connected to the lock-up piston 71. In other words, the lock-up damper 90 is connected to both the turbine hub 64 and the lock-up piston 71. As mentioned above, the lock-up damper 90 is provided in the torque transmission path when the lock-up clutch is engaged. That is, when the lock-up clutch 70 is switched to the engaged state, engine torque is transmitted from the front cover 72 to the lock-up piston 71. The engine torque transmitted to the lock-up piston 71 is then transmitted from the outer plate 91 of the lock-up damper 90 through the coil springs 96 and 97 to the inner plate 94. The engine torque transmitted to the inner plate 94 of the lock-up damper 90 is then transmitted to the turbine shaft 67 via the turbine hub 64. In this way, when the lock-up clutch is engaged, torque is transmitted between the crankshaft 36 and the turbine shaft 67 via the lock-up damper 90.

[0026] Next, the operating state of the lock-up damper 90 will be explained. Figure 7 is a diagram showing an example of the operating state of the lock-up damper 90. Figure 7 shows the lock-up damper 90 operating in the drive state and the lock-up damper 90 operating in the coast state. In addition, in Figures 6 and 7, a virtual point Po is shown on the outer plate 91 as a marker to clarify the relative position of the outer plate 91 and the inner plate 94, and a virtual point Pi is shown on the inner plate 94 as a marker. The arrow α shown in Figure 7 is an arrow indicating the rotation direction of the outer plate 91 and the inner plate 94.

[0027] During acceleration, when the accelerator pedal is pressed, the engine torque increases, and torque is transmitted from the crankshaft 36 to the turbine shaft 67. In other words, as shown by arrow S1 in the drive state of Figure 7, torque is transmitted from the outer plate 91 to the inner plate 94 via the coil spring 96, so the outer plate 91 moves ahead of the inner plate 94 while compressing the coil spring 96. In this drive state of the lock-up damper 90, as shown by arrow Xd, the outer plate 91 rotates relative to the inner plate 94 toward the drive side. In other words, the lock-up damper 90 is twisted toward the drive side, and relative rotation between the outer plate 91 and the inner plate 94 is permitted.

[0028] On the other hand, during deceleration driving, when the accelerator pedal is released, the engine torque decreases, and torque is transmitted from the turbine shaft 67 to the crankshaft 36. In other words, as shown by arrow S2 in the coasting state of Figure 7, torque is transmitted from the inner plate 94 to the outer plate 91 via the coil spring 97, so the inner plate 94 moves ahead of the outer plate 91 while compressing the coil spring 97. In this coasting state of the lock-up damper 90, as shown by arrow Xc, the outer plate 91 rotates relative to the inner plate 94 on the coast side, opposite to the drive side. In other words, the lock-up damper 90 is twisted on the coast side, and relative rotation between the outer plate 91 and the inner plate 94 is permitted.

[0029] [Wear between turbine hub and lock-up piston] As mentioned above, while the lock-up clutch is engaged, the lock-up damper 90 operates in a drive state or coast state in response to engine torque fluctuations. In other words, the outer plate 91 and the inner plate 94 rotate relative to each other in response to engine torque fluctuations. Here, the cylindrical portion 73 of the lock-up piston 71 is connected to the outer plate 91, and the hub portion 66 of the turbine hub 64 is connected to the inner plate 94. Therefore, when the outer plate 91 and the inner plate 94 rotate relative to each other, the hub portion 66 and the cylindrical portion 73 which is slidably supported by it also rotate relative to each other.

[0030] Thus, when the hub portion 66 and the cylindrical portion 73 rotate relative to each other, if the sliding surface pressure and sliding speed between the hub portion 66 and the cylindrical portion 73 increase excessively, there is a risk that wear will progress on the outer surface 66a of the hub portion 66 and the inner surface 73a of the cylindrical portion 73. This increased wear on the hub portion 66 and the cylindrical portion 73 widens the gap between the hub portion 66 and the cylindrical portion 73, causing the hydraulic fluid to circulate, that is, it causes hydraulic fluid to flow from the apply chamber 75 to the release chamber 76, increasing the workload of the oil pump 22. Furthermore, the increased wear on the hub portion 66 and the cylindrical portion 73 causes hydraulic fluid to flow from the apply chamber 75 to the release chamber 76, which can lead to a malfunction of the lock-up clutch 70. For this reason, the control system 30 performs wear suppression control, which will be described later, in order to suppress the wear occurring on the hub portion 66 and the cylindrical portion 73.

[0031] [Wear suppression control] Figure 8 is a flowchart showing an example of the execution procedure for wear suppression control, and Figure 9 is a diagram showing an example of the sliding surface pressure P estimated based on engine speed and engine torque. Figure 10 is a cross-sectional view showing the sliding portion and its vicinity between the hub portion 66 and the cylindrical portion 73, and Figures 11 and 12 are schematic diagrams showing an example of the load applied to the sliding portion between the hub portion 66 and the cylindrical portion 73. Each step of the wear suppression control shown in Figure 8 is a process executed by the processor 50 that constitutes the control system 30. Furthermore, the wear suppression control shown in Figure 8 is a control that is executed by the control system 30 at predetermined intervals after the control system 30 is started.

[0032] As shown in Figure 8, in step S10, it is determined whether or not the lock-up clutch 70 is engaged. If it is determined in step S10 that the lock-up clutch 70 is engaged, the process proceeds to step S11, where the sliding surface pressure P between the hub portion 66 and the cylindrical portion 73 is estimated based on the engine speed and engine torque. In other words, as shown in Figure 9, the sliding surface pressure P is estimated to be higher as the engine speed increases, and the sliding surface pressure P is estimated to be higher as the engine torque increases. Here, the sliding surface pressure P is the surface pressure acting on the sliding portion between the hub portion 66 and the cylindrical portion 73, and is the surface pressure determined based on the contact of two parallel cylinders in Hertz's contact theory. In other words, the sliding surface pressure P is the surface pressure that can be determined from Hertz's contact theory by using the radial load applied to the sliding portion between the hub portion 66 and the cylindrical portion 73, the radius of curvature of the outer surface 66a of the hub portion 66, the radius of curvature of the inner surface 73a of the cylindrical portion 73, Poisson's ratio, Young's modulus, and the contact width between the hub portion 66 and the cylindrical portion 73. As the contact width between the hub portion 66 and the cylindrical portion 73, for example, as shown in Figure 10, the width obtained by subtracting the width Wb of the O-ring groove 100 from the width Wa of the portion where the hub portion 66 and the cylindrical portion 73 face each other (Wa-Wb) is used.

[0033] A first radial load W1 can be considered as a radial load applied to the sliding part, determined by the eccentricity of the rotating body assembly 101, which consists of a lock-up piston 71, a lock-up damper 90, and a turbine runner 63. As shown in Figure 11, if the center of gravity position G1 of the rotating body assembly 101 is off-center from the rotation center Ct, a first radial load W1 is generated radially on the rotating body assembly 101. The magnitude of the first radial load W1 is determined by the eccentricity and rotational speed of the rotating body assembly 101. Here, since the eccentricity of the mass-produced rotating body assembly 101 is within a predetermined design range, the control system 30 can estimate the first radial load W1 based on the engine speed, which is the rotational speed of the rotating body assembly 101. In other words, the control system 30 estimates a higher sliding surface pressure P as the engine speed increases, because the first radial load W1 increases as the engine speed increases.

[0034] Furthermore, a second radial load W2 can be considered as a radial load input to the sliding part, which is determined by the variation in the coil springs 96 and 97 that constitute the lock-up damper 90. As shown in Figure 12, if there is variation in the spring force of the coil spring 97, a second radial load W2 will be generated radially on the inner plate 94. For example, if the spring force Fs1 of coil spring 97a is greater than the spring forces Fs2 of the other coil springs 97b and 97c, the balance of spring forces acting on the inner plate 94 will be disrupted, and a second radial load W2 will be generated on the inner plate 94. Here, since the variation in spring force of mass-produced coil springs 96 and 97 is within a predetermined design range, the control system 30 can estimate the second radial load W2 based on the engine torque that expands and contracts the coil springs 96 and 97. In other words, the control system 30 estimates the sliding surface pressure P to be higher as the engine torque increases, because the second radial load W2 increases as the engine torque increases.

[0035] As shown in the flowchart of Figure 8, in step S11, once the sliding surface pressure P is estimated based on the engine speed and engine torque, the process proceeds to step S12, where the sliding speed V between the hub portion 66 and the cylindrical portion 73 is estimated based on the rate of change of the engine torque. Here, Figure 13 shows an example of the relationship between engine torque and sliding speed V. As shown in Figure 13, when the engine torque decreases (symbol a1), the absolute value of the rate of change of the engine torque (hereinafter referred to as the torque change rate) increases (symbol b1). Thus, when the engine torque decreases, the lock-up damper 90 is twisted towards the coast (symbol c1), and the absolute value of the twisting speed of the lock-up damper 90, that is, the absolute value of the sliding speed V between the hub portion 66 and the cylindrical portion 73, increases (symbol d1). Also, when the engine torque increases (symbol a2), the absolute value of the torque change rate increases (symbol b2). Thus, as engine torque increases, the lock-up damper 90 is twisted towards the drive side (symbol c2), and the absolute value of the sliding speed V between the hub portion 66 and the cylindrical portion 73 increases (symbol d2). For this reason, the control system 30 estimates the sliding speed V to be higher as the torque change rate associated with the increase or decrease in engine torque increases.

[0036] As explained above, in step S11 the sliding surface pressure P is estimated, and in step S12 the sliding speed V is estimated. Then the process proceeds to step S13, where the PV value, which is the product of the sliding surface pressure P and the sliding speed V, is calculated. In the following step S14, it is determined whether the PV value exceeds a predetermined threshold Xpv. If it is determined in step S14 that the PV value exceeds the threshold Xpv, it indicates that wear between the hub portion 66 and the cylindrical portion 73 is progressing significantly, so the process proceeds to step S15, where torque change suppression processing for the engine 12 is executed. In other words, since the sliding surface pressure P and sliding speed V are high, which accelerates wear between the hub portion 66 and the cylindrical portion 73, torque change suppression processing is executed to gradually change the engine torque. On the other hand, if it is determined in step S14 that the PV value is less than or equal to the threshold Xpv, it indicates that wear between the hub portion 66 and the cylindrical portion 73 is suppressed, so the routine is exited without executing torque change suppression processing.

[0037] [Torque change suppression process] Figure 14 shows an example of a threshold Xpv compared to the PV value. As indicated by the symbol x1 in Figure 14, in the region where the PV value exceeds the threshold Xpv, the sliding surface pressure P and sliding speed V between the hub portion 66 and the cylindrical portion 73 are high, which may accelerate wear between the hub portion 66 and the cylindrical portion 73. Therefore, when increasing or decreasing engine torque under conditions where the PV value exceeds the threshold Xpv, a torque change suppression process is performed to gradually change the engine torque. As will be described later, by performing the torque change suppression process, it is possible to suppress an excessive increase in the sliding speed V, and thus suppress an excessive increase in the PV value. That is, as indicated by the arrow β in Figure 14, an excessive increase in the sliding speed V is suppressed in order to decrease the PV value.

[0038] Figure 15 shows an example of the execution status of the torque change suppression process. Figure 15 shows a situation in which the PV value exceeds the threshold Xpv during the process of decreasing engine torque. In addition, Figure 15 shows the changes in engine torque etc. when the torque change suppression process is performed as an example with a solid line, and the changes in engine torque etc. when the torque change suppression process is not performed as a comparative example with a dashed line.

[0039] As shown by the solid line in Figure 15, when the PV value exceeds the threshold Xpv during the engine torque decrease process (symbol a1), the target decrease rate of engine torque, i.e., the target rate of change, is lowered from the first target rate Tv1 to the second target rate Tv2 (arrow b1). In other words, when the PV value exceeds the threshold Xpv, the target rate of change of engine torque is set lower than when the PV value falls below the threshold Xpv. Here, the first target rate Tv1 is the target rate of change of engine torque set when the PV value is less than or equal to the threshold Xpv, and the second target rate Tv2 is the target rate of change of engine torque set when the PV value exceeds the threshold Xpv. In this way, by lowering the target rate of change to the second target rate Tv2 as the PV value increases, an excessive increase in the rate of change of torque can be suppressed (symbol c1), and the engine torque can be reduced gradually (symbol d1). This suppresses an excessive increase in the sliding speed V (symbol e1) and an excessive increase in the PV value (symbol a2), thereby suppressing wear between the hub portion 66 and the cylindrical portion 73.

[0040] On the other hand, as shown by the dashed line in Figure 15, if the engine torque is reduced while maintaining the target change speed at the first target speed Tv1, the torque change speed will increase excessively (symbol f1), and the engine torque will decrease rapidly (symbol g1). In this case, the sliding speed V will increase excessively (symbol h1), and the PV value will increase excessively (symbol i1), which may accelerate wear between the hub portion 66 and the cylindrical portion 73. As mentioned above, the control system 30 sets the target change speed of the engine torque lower when the PV value exceeds the threshold Xpv than when the PV value falls below the threshold Xpv. This makes it possible to suppress an excessive increase in the sliding speed V, i.e., an excessive increase in the PV value, and thus suppress wear between the hub portion 66 and the cylindrical portion 73.

[0041] [Other embodiments] In the explanation above, the target rate of change of engine torque is set low during the decrease in engine torque as part of the torque change suppression process. However, this is not the only method, and the engine torque may be changed gradually by other control methods. Figure 16 shows other control examples 1 to 3 in the torque change suppression process. In Figure 16, the change in engine torque when the torque change suppression process is performed is shown by a solid line as an example, and the change in engine torque when the torque change suppression process is not performed is shown by a dashed line as a comparative example.

[0042] As shown in Figure 16 as Control Example 1, when reducing engine torque, the target reduction amount (target change amount) of engine torque may be set to a smaller value as a torque change suppression process. In other words, if the PV value exceeds the threshold Xpv during the engine torque reduction process, the target reduction amount of engine torque may be reduced from the first target reduction amount T1a to the second target reduction amount T1b. That is, when the PV value exceeds the threshold Xpv, the target reduction amount of engine torque may be set to a smaller value than when the PV value is below the threshold Xpv. In this way, even when the target reduction amount of engine torque is reduced in accordance with the increase in PV value, the engine torque can be reduced gradually, thereby suppressing an excessive increase in the sliding speed V, i.e., an excessive increase in the PV value, and thus suppressing wear between the hub portion 66 and the cylindrical portion 73. The first target reduction amount T1a is the target change amount of engine torque set when the PV value is less than or equal to the threshold Xpv, and the second target reduction amount T1b is the target change amount of engine torque set when the PV value exceeds the threshold Xpv.

[0043] As shown in Figure 16 as Control Example 2, when increasing engine torque, the target rate of increase (target rate of change) of engine torque may be set lower as a torque change suppression process. In other words, if the PV value exceeds the threshold Xpv during the process of increasing engine torque, the target rate of increase of engine torque may be lowered from the first target rate T2a to the second target rate T2b. That is, when the PV value exceeds the threshold Xpv, the target rate of increase of engine torque may be set lower than when the PV value is below the threshold Xpv. In this way, even when the target rate of increase of engine torque is lowered in accordance with the increase in PV value, the engine torque can be increased gradually, thereby suppressing an excessive rise in the sliding speed V, i.e., an excessive rise in the PV value, and thus suppressing wear between the hub portion 66 and the cylindrical portion 73. The first target rate T2a is the target rate of change of engine torque set when the PV value is less than or equal to the threshold Xpv, and the second target rate T2b is the target rate of change of engine torque set when the PV value exceeds the threshold Xpv.

[0044] As shown in Figure 16 as Control Example 3, when increasing engine torque, the target increase amount (target change amount) of engine torque may be set to a smaller value as a torque change suppression process. In other words, if the PV value exceeds the threshold Xpv during the process of increasing engine torque, the target increase amount of engine torque may be reduced from the first target increase amount T3a to the second target increase amount T3b. That is, when the PV value exceeds the threshold Xpv, the target increase amount of engine torque may be set to a smaller value than when the PV value is below the threshold Xpv. In this way, even if the target increase amount of engine torque is reduced in accordance with the increase in PV value, the engine torque can be increased gradually, thereby suppressing an excessive rise in the sliding speed V, i.e., an excessive rise in the PV value, and thus suppressing wear between the hub portion 66 and the cylindrical portion 73. The first target increase amount T3a is the target change amount of engine torque set when the PV value is less than or equal to the threshold Xpv, and the second target increase amount T3b is the target change amount of engine torque set when the PV value exceeds the threshold Xpv.

[0045] The present invention is not limited to the embodiments described above, and it goes without saying that various modifications are possible without departing from the spirit of the invention. For example, although the control system 30 is configured with three control units in the above description, it is not limited to this, and the control system 30 may be configured with one control unit, or with two or four or more control units. Also, although the lock-up clutch 70 is engaged based on the vehicle speed in the above description, it is not limited to this, and the lock-up clutch 70 may be engaged based on the vehicle speed and the required driving force.

[0046] In the above description, the torque change suppression process is executed immediately when the PV value exceeds the threshold Xpv, but this is not the only way. For example, a counting process may be executed each time the PV value exceeds the threshold Xpv, and the torque change suppression process may be executed only when the PV value exceeds the threshold Xpv after a predetermined number of counts. Also, in the above description, a fixed value threshold Xpv is used, but this is not the only way. For example, the threshold Xpv may be changed based on the sliding speed V, or based on the sliding surface pressure P. When the engine control unit 28 calculates the engine torque, it may calculate the engine torque from the intake air amount and fuel injection amount, or from the angular acceleration of the crankshaft 36. Furthermore, by using a torque sensor that detects the distortion of the rotating shaft, the engine torque may be calculated from the distortion of the rotating shaft. [Explanation of symbols]

[0047] 10 Vehicle control devices 11 vehicles 12 Engines 15 Torque Converter 30 Control Systems 36 Crankshaft 50 processors 51 Main memory (memory) 63 Turbine Runner 64 Turbine Hub 65 Flange section 66 Hub section 66a Outer surface 67 Turbine shaft 71 Lock-up piston 73 Cylindrical section 74 Disc section 90 Lock-up damper (damper mechanism) P sliding surface pressure V sliding speed Xpv threshold

Claims

1. A vehicle control device installed in a vehicle, A turbine hub comprising a flange portion connected to the turbine runner of a torque converter and a hub portion connected to the turbine shaft, A lock-up piston comprising a cylindrical portion slidably supported on the outer circumferential surface of the hub portion, and a disc portion extending radially outward from the cylindrical portion, A damper mechanism is connected to both the turbine hub and the lock-up piston, allowing relative rotation between the hub portion and the cylindrical portion. A control system comprising a processor and memory connected to each other in a manner that enables communication, which controls the engine connected to the torque converter, It has, The control system is With the lock-up piston fastened to the engine's crankshaft, the sliding surface pressure between the hub portion and the cylindrical portion is estimated such that it increases as the engine speed increases and as the engine torque increases. With the lock-up piston fastened to the engine's crankshaft, the absolute value of the sliding speed between the hub portion and the cylindrical portion is estimated such that it increases as the absolute value of the rate of change of engine torque increases. With the lock-up piston fastened to the engine's crankshaft, the PV value, which is the product of the sliding surface pressure and the absolute value of the sliding speed, is calculated. When the PV value exceeds a threshold for determining wear between the hub portion and the cylindrical portion, the engine torque is changed more gradually than when the PV value falls below the threshold. Vehicle control device.

2. In the vehicle control device according to claim 1, The control system is When the PV value exceeds the threshold, the target rate of change of engine torque is set lower than when the PV value falls below the threshold. Vehicle control device.

3. In the vehicle control device according to claim 1, The control system is When the PV value exceeds the threshold, the target change in engine torque is set to be smaller than when the PV value falls below the threshold. Vehicle control device.

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