Vehicle drive apparatus

Abstract

To appropriately protect a friction clutch.SOLUTION: A vehicle drive apparatus includes: a friction clutch which controls a torque distribution ratio between drive wheels; and a control system which executes clutch protection control to suppress a slip state of the friction clutch. In a situation where the friction clutch is in a first lubrication state, the control system executes the clutch protection control when a slip amount of the friction clutch exceeds a first threshold. In a situation where the friction clutch is in a second lubrication state with less oil than in the first lubrication state, the control system executes the clutch protection control when the slip amount of the friction clutch exceeds a second threshold smaller than the first threshold.SELECTED DRAWING: Figure 12

Description

[Technical field]

[0001] The present disclosure relates to a vehicle drive device. [Background technology]

[0002] Vehicles such as automobiles have a friction clutch that controls the torque distribution ratio of driving wheels (see Patent Documents 1 to 3). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2004-245318 A [Patent Document 2] JP 2011-149515 A [Patent Document 3] JP 2020-122561 A Summary of the Invention [Problem to be solved by the invention]

[0004] However, if the slip of the friction clutch is excessively increased, there is a risk that the friction clutch may be deteriorated due to heat generation, etc. For this reason, there is a demand for appropriate protection of the friction clutch. [Means for solving the problem]

[0005] According to the present disclosure, a vehicle drive device is a vehicle drive device provided in a vehicle, and includes: a friction clutch provided in a power transmission path connecting a power source and drive wheels, and controlling a torque distribution ratio of the drive wheels; a lubrication system including an oil pump that discharges oil and supplies the oil to the friction clutch; and a control system including a processor and a memory communicatively connected to each other, and executing clutch protection control to suppress a slip state of the friction clutch, wherein the lubrication states of the friction clutch include a first lubrication state and a second lubrication state in which the amount of oil is less than the first lubrication state, and the control system executes the clutch protection control when the amount of slip of the friction clutch exceeds a first threshold value when the friction clutch is in the first lubrication state, and executes the clutch protection control when the amount of slip of the friction clutch exceeds a second threshold value that is smaller than the first threshold value when the friction clutch is in the second lubrication state. Effect of the Invention

[0006] According to the present disclosure, the friction clutch can be appropriately protected. [Brief description of the drawings]

[0007] [Figure 1] 1 is a diagram illustrating an example of a vehicle equipped with a vehicle drive device according to an embodiment. [Diagram 2] FIG. 2 is a diagram illustrating an example of a power unit and a control system. [Diagram 3] FIG. 2 is a diagram showing a portion of an oil supply system. [Figure 4] FIG. 2 is a diagram illustrating an example of a basic structure of a control unit. [Diagram 5] 5 is a flowchart showing an example of a procedure for executing clutch lubrication determination. [Figure 6] FIG. 11 is a diagram illustrating an example of a relationship between a time threshold value and an oil temperature. [Figure 7] 10 is a flowchart showing an example of a procedure for determining a leakage time. [Figure 8] 11 is a timing chart showing an example of a transition of a leakage time. [Figure 9] 5 is a flowchart showing an example of a procedure for executing clutch load determination. [Figure 10] 5 is a flowchart showing an example of a procedure for executing clutch load determination. [Figure 11] FIG. 4 is a diagram showing an example of a characteristic line used when the lubrication state of the transfer clutch is an appropriate amount of oil. [Figure 12] FIG. 11 is a diagram showing an example of a characteristic line used when the lubrication state of the transfer clutch is in an oil shortage state. [Figure 13] FIG. 11 is a diagram showing an example of a rotation threshold value obtained from a characteristic line. [Figure 14] 4 is a flowchart showing an example of a procedure for executing clutch protection control. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0008] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the drawings. In the following description, the same or substantially the same configurations and elements will be denoted by the same reference numerals and repeated description will be omitted.

[0009] <Power unit> Fig. 1 is a diagram showing an example of a vehicle 11 equipped with a vehicle drive device 10 according to an embodiment. As shown in Fig. 1, the vehicle drive device 10 has a power unit 14 consisting of an engine 12 and a motor generator 13. A rear wheel output shaft 15 of the power unit 14 is connected to rear wheels 18 via a propeller shaft 16 and a rear differential mechanism 17. The power unit 14 also has a front differential mechanism 19, which is connected to front wheels 20 via a drive shaft (not shown).

[0010] 2 is a diagram showing an example of the power unit 14 and a control system 70. As shown in FIG. 2, the power unit 14 has an engine (power source) 12, a torque converter 21, an input clutch 22, a motor generator (power source) 13, a speed change mechanism 23, and a transfer clutch 24. The engine 12 and the motor generator 13 are connected to each other via the torque converter 21, a gear train 25, and the input clutch 22. The motor generator 13 and the speed change output shaft 26 are connected to each other via the gear train 27, the speed change input shaft 28, and the speed change mechanism 23. In this way, the engine 12 and the speed change output shaft 26 are connected to each other via a power source drive path 30 consisting of the torque converter 21, the gear train 25, the input clutch 22, the motor generator 13, the gear train 27, the speed change input shaft 28, and the speed change mechanism 23.

[0011] As shown in Fig. 1 and Fig. 2, the transmission output shaft 26 and the front wheels (drive wheels) 20 are connected to each other via a front wheel drive path 33 consisting of a gear train 31, a front wheel output shaft 32, a front differential mechanism 19, etc. Also, the transmission output shaft 26 and the rear wheels (drive wheels) 18 are connected to each other via a rear wheel drive path 34 consisting of a transfer clutch 24, a rear wheel output shaft 15, a propeller shaft 16, a rear differential mechanism 17, etc. In this way, the engine 12 and the front wheels 20 are connected to each other via a power transmission path 40 consisting of the power source drive path 30 and the front wheel drive path 33. Also, the engine 12 and the rear wheels 18 are connected to each other via a power transmission path 41 consisting of the power source drive path 30 and the rear wheel drive path 34.

[0012] <Transfer clutch> 2, the rear wheel drive path 34 constituting the power transmission path 41 is provided with a transfer clutch (friction clutch) 24 that controls the torque distribution ratio between the front wheels 20 and the rear wheels 18. The transfer clutch 24 has a clutch drum 42 connected to the transmission output shaft 26, and a clutch hub 43 connected to the rear wheel output shaft 15. The transfer clutch 24 also has a plurality of friction plates 44 attached to the clutch drum 42, and a plurality of friction plates 45 attached to the clutch hub 43. The transfer clutch 24 also has an electromagnetic drive unit 47 equipped with a piston 46 that faces the friction plates 44, 45.

[0013] The transfer clutch 24 is switched to an engaged state by moving the piston 46 of the electromagnetic drive unit 47 toward the forward position to engage the friction plates 44, 45 with each other. On the other hand, the transfer clutch 24 is switched to a released state by moving the piston 46 of the electromagnetic drive unit 47 toward the retracted position opposite the forward position to release the engagement of the friction plates 44, 45. In addition, by adjusting the amount of movement of the piston 46 between the forward position and the retracted position, the friction plates 44, 45 can be brought into contact with each other while sliding, and the transfer clutch 24 can be controlled to a slip state.

[0014] By controlling the transfer clutch 24 to an engaged state, the rotational speeds of the front wheels 20 and the rear wheels 18 can be made to match with each other, and the torque distribution ratio between the front wheels 20 and the rear wheels 18 can be controlled to "50:50". By controlling the transfer clutch 24 to a released state, the torque transmission to the rear wheels 18 can be cut off, and the torque distribution ratio between the front wheels 20 and the rear wheels 18 can be controlled to "100:0". Furthermore, by controlling the transfer clutch 24 to a slip state, the torque distribution ratio between the front wheels 20 and the rear wheels 18 can be arbitrarily adjusted within a predetermined range.

[0015] <Oil supply system> As shown in FIG. 2, the vehicle drive device 10 has an oil supply system (lubrication system) 50 that supplies oil to the transfer clutch 24 and the like. The oil supply system 50 has an oil pump 51 driven by the engine 12 and the like, and a valve body 52 consisting of a plurality of electromagnetic valves and oil passages. The oil discharged from the oil pump 51 is adjusted in supply destination, pressure, and flow rate through the valve body 52, and is supplied to each device such as the transmission mechanism 23 and the transfer clutch 24. The oil supplied from the valve body 52 to each device is used as oil for control, lubrication, or cooling. In addition, a lubricating oil passage 53 that supplies lubricating oil (hereinafter referred to as lubricating oil) to the transfer clutch 24 is connected to the valve body 52. ​​The lubricating oil passage 53 that guides the lubricating oil can be formed in the transmission output shaft 26 or the rear wheel output shaft 15, etc.

[0016] The rotor 54 of the oil pump 51 is connected to a pump shell 56 of the torque converter 21 via a chain mechanism 55 equipped with a one-way clutch. The rotor 54 of the oil pump 51 is also connected to the transmission input shaft 28 via a chain mechanism 57 equipped with a one-way clutch. In this way, the rotor 54 of the oil pump 51 is connected to the crankshaft 58 of the engine 12 and to the transmission input shaft (rotating shaft) 28 constituting the power transmission paths 40, 41. As a result, when the engine 12 is in operation, the driving force is transmitted from the crankshaft 58 to the oil pump 51 via the chain mechanism 55. On the other hand, during motor running in which the transmission input shaft 28 rotates even when the engine 12 is in a stopped state, the driving force is transmitted from the transmission input shaft 28 to the oil pump 51 via the chain mechanism 57. Note that, during motor running in which the vehicle 11 runs with the engine 12 stopped, the input clutch 22 located between the engine 12 and the motor generator 13 is released to separate the engine 12 from the power unit 14.

[0017] FIG. 3 is a diagram showing a part of the oil supply system 50. In FIG. 3, an electromagnetic valve for controlling the pressure and supply destination of the oil is omitted. As shown in FIG. 3, a strainer 61 arranged in an oil pan 60 is connected to a suction port 51i of the oil pump 51 through a suction oil passage 62. In addition, a first device group 63 and a second device group 64 are connected to a discharge port 51o of the oil pump 51 through a valve body 52. ​​That is, the oil supplied from the oil pan 60 to the valve body 52 by the drive of the oil pump 51 is supplied to the first device group 63 and the second device group 64 through the valve body 52. ​​Here, the first device group 63 is a device group consisting of various devices such as the transmission mechanism 23 that consumes a large amount of oil, and the second device group 64 is a device group consisting of various devices such as the transfer clutch 24 that consumes a small amount of oil. As will be described later, the first device group 63 is supplied with oil preferentially to the second device group 64 by the operation of a lubrication valve 69 provided in the valve body 52.

[0018] The valve body 52 has a line pressure passage 65 connected to the discharge port 51o of the oil pump 51, a first supply oil passage 66 connected to the line pressure passage 65 to supply oil to the first device group 63, and a second supply oil passage 67 connected to the line pressure passage 65 to supply oil to the second device group 64. The valve body 52 also has a relief valve 68 connected to the line pressure passage 65 to adjust the pressure of the oil in the line pressure passage 65, and a lubrication valve 69 provided in the second supply oil passage 67 to block the second supply oil passage 67. The lubrication valve 69 of the valve body 52 operates to a closed state to block the second supply oil passage 67 when the hydraulic pressure in the line pressure passage 65 falls below a predetermined hydraulic pressure, and operates to an open state to communicate the second supply oil passage 67 when the hydraulic pressure in the line pressure passage 65 exceeds the predetermined hydraulic pressure.

[0019] When the rotation speed of the oil pump 51 is low and the amount of discharged oil is small, the lubrication valve 69 operates to a closed state as the hydraulic pressure in the line pressure path 65 drops, and the oil supply to the second device group 64 including the transfer clutch 24 is stopped. In this way, when the lubrication valve 69 is closed due to a drop in hydraulic pressure, the oil supply to the second device group 64 is stopped, while the oil supply to the first device group 63 is performed. On the other hand, when the rotation speed of the oil pump 51 is high and the amount of discharged oil is large, the lubrication valve 69 operates to an open state as the hydraulic pressure in the line pressure path 65 rises, and the oil supply to both the first device group 63 and the second device group 64 is performed.

[0020] As described above, when the rotation speed of the oil pump 51 decreases and the lubrication valve 69 operates to the closed state, the supply of lubricating oil to the transfer clutch 24 of the second device group 64 is stopped. The situation in which the lubrication valve 69 operates to the closed state is a situation in which the vehicle starts to run in motor running with the engine 12 stopped, and the vehicle speed is low and the rotation speed of the transmission input shaft 28 is slow. In other words, the oil supply system 50 stops the supply of lubricating oil to the transfer clutch 24 when the engine 12 is stopped and the running speed of the vehicle 11 is below a predetermined speed threshold.

[0021] Furthermore, if the oil supply to the transfer clutch 24 is stopped at the start of motor-driven running, the lubrication state of the transfer clutch 24 will become an oil shortage state (second lubrication state) where there is little lubricating oil, depending on the length of the leakage time Tb1 corresponding to the outflow time of the lubricating oil, that is, the soak time, as described later. The transfer clutch 24 has a structure that gradually drops the lubricating oil from the clutch drum 42 toward the oil pan 60. As described later, the soak time is the time from when the driver turns the start switch 90 OFF to when the driver turns it ON.

[0022] As described above, when the rotation speed of the oil pump 51 increases and the lubrication valve 69 operates to the open state, lubrication oil is supplied to the transfer clutch 24 of the second device group 64. In this way, the situation in which the lubrication valve 69 operates to the open state is a situation in which the oil pump 51 is driven by the engine 12 in operation, or a situation in which the vehicle speed is high even when the vehicle is traveling by motor. In addition, when the lubrication valve 69 opens and lubrication oil is supplied to the transfer clutch 24, as described later, the lubrication state of the transfer clutch 24 becomes an appropriate oil amount state (first lubrication state) in which lubrication oil is appropriately supplied. In other words, the oil shortage state of the transfer clutch 24 described above is a state in which the amount of lubrication oil is less than the appropriate oil amount state of the transfer clutch 24.

[0023] <Control system> As shown in FIG. 2, the vehicle drive device 10 has a control system 70 consisting of a plurality of electronic control units. The electronic control units constituting the control system 70 include a transmission control unit 71, an engine control unit 72, and a motor control unit 73. The transmission control unit 71 is an electronic control unit that outputs control signals to the valve body 52, the electromagnetic drive unit 47, and the like. The engine control unit 72 is an electronic control unit that outputs control signals to the throttle valve 74, the injector 75, the ignition device 76, and the like. The motor control unit 73 is an electronic control unit that outputs control signals to an inverter 77 connected to the motor generator 13, and the like. A battery pack 78 is connected to the inverter 77, which is a power conversion device.

[0024] Further, as an electronic control unit constituting the control system 70, there is a vehicle control unit 80 that outputs control signals to the above-mentioned control units 71, 72, and 73. These control units 71, 72, 73, and 80 are communicably connected to each other via an in-vehicle network 81 such as a CAN (Controller Area Network). The vehicle control unit 80 sets operation targets for the power unit 14 and the like based on input information from various control units and various sensors described later. Furthermore, the vehicle control unit 80 generates control signals according to operation targets for the power unit 14 and the like, and outputs these control signals to the engine control unit 72, the motor control unit 73, the transmission control unit 71, and the like.

[0025] The sensors connected to the vehicle control unit 80 include an accelerator sensor 82 that detects the amount of operation of an accelerator pedal, and a brake sensor 83 that detects the amount of operation of a brake pedal. The sensors connected to the vehicle control unit 80 also include a vehicle speed sensor 84 that detects the vehicle speed, which is the traveling speed of the vehicle 11, and a temperature sensor 85 that detects the oil temperature. The sensors connected to the vehicle control unit 80 also include a rotation sensor 86 that detects the rotation speed of the crankshaft 58, a rotation sensor 87 that detects the rotation speed of the transmission input shaft 28, a rotation sensor 88 that detects the rotation speed of the transmission output shaft 26, and a rotation sensor 89 that detects the rotation speed of the rear wheel output shaft 15.

[0026] In addition, the vehicle control unit 80 is connected to a start switch 90 that is operated when the control system 70 is started and stopped. Each time the start switch 90 is pressed by the driver, the control system 70 switches the power supply mode between the ON mode and the OFF mode. For example, when the start switch 90 is pressed when the power supply mode is the OFF mode, that is, when the start switch 90 is turned ON by the driver, the power supply mode is switched from the OFF mode to the ON mode. Also, when the start switch 90 is pressed when the power supply mode is the ON mode, that is, when the start switch 90 is turned OFF by the driver, the power supply mode is switched from the ON mode to the OFF mode. The ON mode is a power supply mode in which the control system 70 is started and the vehicle can run, and the OFF mode is a power supply mode in which the control system 70 is stopped and the vehicle cannot run. The start switch 90 is also called an ignition switch.

[0027] Fig. 4 is a diagram showing an example of the basic structure of the control units 71, 72, 73, and 80. As shown in Fig. 4, the control units 71, 72, 73, and 80, which are electronic control units, have a microcontroller 102 incorporating a processor 100 and a main memory (memory) 101, etc. A predetermined program is stored in the main memory 101, and the program is executed by the processor 100. The processor 100 and the main memory 101 are connected to each other so as to be able to communicate with each other. Note that a plurality of processors 100 may be incorporated in the microcontroller 102, and a plurality of main memories 101 may be incorporated in the microcontroller 102.

[0028] Moreover, the control units 71, 72, 73, and 80 each have an input circuit 103, a drive circuit 104, a communication circuit 105, an external memory 106, and a power supply circuit 107. The input circuit 103 converts signals input from various sensors into signals that can be input to the microcontroller 102. The drive circuit 104 generates drive signals for devices such as the valve body 52 and the electromagnetic drive unit 47 described above based on signals output from the microcontroller 102. The communication circuit 105 converts signals output from the microcontroller 102 into communication signals directed to other control units. The communication circuit 105 also converts communication signals received from other control units into signals that can be input to the microcontroller 102. Furthermore, the power supply circuit 107 supplies a stable power supply voltage to the microcontroller 102, the input circuit 103, the drive circuit 104, the communication circuit 105, the external memory 106, and the like. Furthermore, the external memory 106, which is a non-volatile memory or the like, stores programs and various data.

[0029] <Transfer clutch protection> Incidentally, the control system 70 executes clutch protection control to suppress the slip state of the transfer clutch 24 in order to protect the transfer clutch 24 from excessive heat generation, etc. Also, as described above, the lubrication state of the transfer clutch 24 includes an appropriate oil amount state in which lubricating oil is appropriately supplied to the transfer clutch 24, and an oil shortage state in which the amount of lubricating oil is less than that in the appropriate oil amount state. For this reason, it is required to execute the clutch protection control appropriately according to the lubrication state of the transfer clutch 24. In other words, since it is expected that the lubricating oil will be in an oil shortage state in which the amount of lubricating oil is less at the start of motor running, it is necessary to execute the clutch protection control appropriately according to the lubrication state of the transfer clutch 24.

[0030] Below, clutch lubrication determination, leakage time determination, and clutch load determination will be described, followed by a description of clutch protection control. Each step of clutch lubrication determination, leakage time determination, clutch load determination, and clutch protection control, which will be described later, is executed by processor 100 constituting control system 70. Also, clutch lubrication determination, leakage time determination, clutch load determination, and clutch protection control are controls executed by control system 70 at predetermined intervals.

[0031] <Clutch lubrication judgment> FIG. 5 is a flowchart showing an example of a procedure for executing clutch lubrication determination. FIG. 6 is a diagram showing an example of the relationship between the time threshold value Xa1 and the oil temperature. As shown in FIG. 5, the control system 70 proceeds to step S10 and determines whether the lubrication valve 69 is in an open state. As described above, the lubrication valve 69 operates in an open state when the oil pump 51 is driven and the oil pressure in the line pressure passage 65 exceeds a predetermined oil pressure. Therefore, the control system 70 determines that the lubrication valve 69 is in an open state when the rotation speed of the crankshaft 58 exceeds a predetermined speed or when the rotation speed of the transmission input shaft 28 exceeds a predetermined speed. Also, for example, the control system 70 may determine that the lubrication valve 69 is in an open state when the vehicle speed exceeds a predetermined speed, or may determine that the lubrication valve 69 is in an open state when the oil pressure in the line pressure passage 65 exceeds a predetermined oil pressure.

[0032] When the control system 70 determines in step S10 that the lubrication valve 69 is in an open state, the process proceeds to step S11, where it counts the supply time Ta1, which is the time that has elapsed since the lubrication valve 69 was opened. Then, the control system 70 proceeds to step S12, where it determines whether the supply time Ta1 exceeds a predetermined time threshold Xa1. Here, as shown in FIG. 6, the time threshold Xa1 is set shorter as the oil temperature increases. In other words, when the oil temperature is high, the oil viscosity is low and the oil flows easily, so the time threshold Xa1 is set shorter as the oil temperature increases.

[0033] 5, when the control system 70 determines in step S12 that the supply time Ta1 exceeds the time threshold value Xa1, the lubricating oil is being sufficiently supplied to the transfer clutch 24, and the process proceeds to step S13, where the appropriate oil amount flag FLa is set (FLa=1). The situation in which the appropriate oil amount flag FLa is set means that the lubrication state of the transfer clutch 24 is an appropriate oil amount state. Note that when the control system 70 determines in step S12 that the supply time Ta1 is equal to or less than the time threshold value Xa1, a sufficient amount of time has not elapsed since the opening of the lubrication valve 69, and the process proceeds to step S10, where the control system 70 again determines whether the lubrication valve 69 is in the open state.

[0034] On the other hand, when the control system 70 determines in step S10 that the lubricating valve 69 is in a closed state, the process proceeds to step S14, where the control system 70 acquires a leakage time Tb1, which is a time during which the lubricating oil flows out. The leakage time Tb1 will be described in detail in the leakage time determination section described later. When the control system 70 acquires the leakage time Tb1 in step S14, the process proceeds to step S15, where the control system 70 determines whether the leakage time Tb1 exceeds a predetermined time threshold value Xb1. When the control system 70 determines in step S15 that the leakage time Tb1 exceeds the time threshold value Xb1, this indicates that a large amount of lubricating oil is flowing out of the transfer clutch 24, and the process proceeds to step S16, where the appropriate oil amount flag FLa is released (FLa=0). The situation in which the appropriate oil amount flag FLa is released means that the lubrication state of the transfer clutch 24 is in an oil shortage state. If the control system 70 determines in step S15 that the leakage time Tb1 is equal to or less than the time threshold value Xb1, then since sufficient lubricating oil is retained in the transfer clutch 24, the control system 70 proceeds to step S13 and sets the appropriate oil amount flag FLa (FLa=1).

[0035] <Leak time determination> Fig. 7 is a flow chart showing an example of a procedure for determining the leakage time. Fig. 8 is a timing chart showing an example of the transition of the leakage time Tb1. As shown in Fig. 7, the control system 70 proceeds to step S20 and determines whether the power supply mode is the ON mode. If the control system 70 determines in step S20 that the power supply mode is the ON mode, that is, if the control system 70 determines that the vehicle 11 is in a state in which it can run, it proceeds to step S21 and determines whether the appropriate oil amount flag FLa is set. If the control system 70 determines in step S21 that the appropriate oil amount flag FLa is set, it proceeds to step S22 and resets the leakage time Tb1 (Tb1 = 0).

[0036] On the other hand, when the control system 70 determines in step S21 that the appropriate oil amount flag FLa has not been reset, the process proceeds to step S23, where it determines whether the power supply mode is the OFF mode. When the control system 70 determines in step S23 that the power supply mode is the OFF mode, that is, when it determines that the vehicle 11 is in a state in which it is not possible to run, the process proceeds to step S24, where it executes a counting process of the leakage time Tb1. When the control system 70 counts the leakage time Tb1 in step S24, the process proceeds to step S25, where it determines whether the power supply mode is the ON mode. When the control system 70 determines in step S25 that the power supply mode is the OFF mode, that is, when the power supply mode is maintained in the OFF mode, the process proceeds to step S24, where it continues the counting process of the leakage time Tb1. On the other hand, when the control system 70 determines in step S25 that the power supply mode is the ON mode, that is, when the power supply mode is switched from the OFF mode to the ON mode, the control system 70 exits the routine.

[0037] That is, when the control system 70 is in the OFF mode in which the oil pump 51 is not driven, it counts the leakage time Tb1, which is the time during which oil flows out from the transfer clutch 24. This leakage time Tb1 is the time during which the supply of lubricating oil to the transfer clutch 24 is stopped. In other words, the leakage time Tb1 is the time from when the driver turns the start switch 90 OFF to when the driver turns it ON, that is, the soak time. Note that even in the OFF mode, some of the functions of the control system 70 are maintained, and the control system 70 can count the leakage time Tb1.

[0038] As shown in FIG. 8, at time t1, the power supply mode is the ON mode (symbol a1), the appropriate oil amount flag FLa is set (symbol b1), and the lubrication valve 69 is in an open state (symbol c1). As shown at time t2, when the power supply mode is switched from the ON mode to the OFF mode (symbol a2), counting of the leakage time Tb1 is started (symbol d1). Also, as shown at time t3, when the power supply mode is switched from the OFF mode to the ON mode (symbol a3), counting of the leakage time Tb1 is stopped (symbol d2). Thereafter, as shown at time t4, when the power supply mode is switched again from the ON mode to the OFF mode (symbol a4), counting of the leakage time Tb1 is started again (symbol d3). Then, at time t5, the leakage time Tb1, which increases with the continuation of the OFF mode, exceeds a predetermined time threshold value Xb1 (symbol d4).

[0039] Next, as shown at time t6, when the power supply mode is switched from the OFF mode to the ON mode (symbol a5), since the leakage time Tb1 has already exceeded the time threshold value Xb1 (symbol d5), it is determined that the lubrication state of the transfer clutch 24 is in an oil shortage state, and the setting of the appropriate oil amount flag FLa is released (symbol b2). Then, as shown at time t7, the lubrication valve 69 is switched to an open state (symbol c2) with the engine starting or the vehicle speed increasing, and when the elapsed time thereafter exceeds the time threshold value Xa1, it is determined that the lubrication state of the transfer clutch 24 is in an appropriate oil amount state, and the appropriate oil amount flag FLa is set (symbol b3). Also, as shown at time t8, when the appropriate oil amount flag FLa is set (symbol b3), the leakage time Tb1 is reset (symbol d6).

[0040] In this way, when the leakage time Tb1 corresponding to the duration of the OFF mode exceeds a predetermined time threshold Xb1 (symbol d5), the control system 70 determines that the lubrication state of the transfer clutch 24 is in an oil shortage state (symbol b2). After that, when a predetermined time has elapsed since the lubrication valve 69 was switched to the open state, the control system 70 determines that the lubrication state of the transfer clutch 24 is in an appropriate oil amount state (symbol b3). In this way, the control system 70 can appropriately determine the oil shortage state of the transfer clutch 24 based on the leakage time Tb1 for the lubricating oil to flow out from the transfer clutch 24. Note that the control system 70 does not execute the reset process of the leakage time Tb1 until it is determined that the transfer clutch 24 is in an appropriate oil amount state, and therefore can appropriately determine the oil shortage state of the transfer clutch 24.

[0041] <Clutch load determination> 9 and 10 are flowcharts showing an example of a procedure for executing clutch load determination. In the flowcharts shown in FIG. 9 and FIG. 10, the lines are connected to each other at the point of reference A. FIG. 11 is a diagram showing an example of characteristic lines La1 and La2 used when the lubrication state of the transfer clutch 24 is an appropriate oil amount state. FIG. 12 is a diagram showing an example of characteristic lines Lb1 and Lb2 used when the lubrication state of the transfer clutch 24 is an oil shortage state. Furthermore, FIG. 13 is a diagram showing an example of a rotation threshold value obtained from the characteristic lines La1, La2, Lb1 and Lb2. Note that the differential rotation (slip amount) ΔN of the transfer clutch 24 described later is the rotation speed difference between the rotation speed of the transmission output shaft 26 and the rotation speed of the rear wheel output shaft 15, that is, the rotation speed difference between the input rotation speed and the output rotation speed of the transfer clutch 24. Also, the engagement instruction torque Tt of the transfer clutch 24 is a control target value that the control system 70 instructs the electromagnetic drive unit 47 of the transfer clutch 24.

[0042] <Clutch load judgement: proper oil level> As shown in FIG. 9, the control system 70 proceeds to step S30 and determines whether the appropriate oil amount flag FLa is set, that is, whether the transfer clutch 24 is in an appropriate oil amount state. When the control system 70 determines that the oil amount is appropriate in step S30, the control system 70 proceeds to step S31 and calculates the load of the transfer clutch 24 (hereinafter, referred to as the clutch load) based on the differential rotation ΔN and the engagement command torque Tt of the transfer clutch 24. When the control system 70 calculates the clutch load in step S31, the control system 70 proceeds to step S32 and determines the region to which the clutch load belongs based on the characteristic lines La1 and La2. Here, as shown in FIG. 11, the region above the characteristic line La1 is the high load region, and the region below the characteristic line La2, which is lower than the characteristic line La1, is the low load region. Also, the region below the characteristic line La1 and above the characteristic line La2 is the medium load region.

[0043] As shown in FIG. 9, the control system 70 proceeds to step S33 and judges whether the clutch load is in the medium load region. If the control system 70 judges in step S33 that the clutch load is in the medium load region, the control system 70 proceeds to step S34 and judges whether a predetermined judgment time has elapsed. If the control system 70 judges in step S34 that the judgment time has elapsed, that is, if the medium load region has continued over the judgment time, the control system 70 proceeds to step S35 and sets the clutch protection flag FLb (FLb=1). The situation in which the clutch protection flag FLb is set is a situation in which it is necessary to protect the transfer clutch 24 from heat generation or the like. On the other hand, if the control system 70 judges in step S34 that the judgment time has not elapsed, the control system 70 proceeds to step S31 and calculates the clutch load again based on the differential rotation ΔN and the engagement command torque Tt.

[0044] If the control system 70 determines in step S33 that the load is not in the medium load range, the process proceeds to step S36, where it determines whether the clutch load is in the high load range. If the control system 70 determines in step S36 that the load is in the high load range, the process proceeds to step S35, where it sets the clutch protection flag FLb (FLb=1). On the other hand, if the control system 70 determines in step S36 that the load is not in the high load range, that is, if the clutch load is in the low load range, the process proceeds to step S36, where it cancels the setting of the clutch protection flag FLb (FLb=0). The situation in which the clutch protection flag FLb is canceled is a situation in which the transfer clutch 24 is not generating excessive heat or the like, and protection of the transfer clutch 24 is not required.

[0045] In this way, when the transfer clutch 24 is in an appropriate oil amount state, the control system 70 determines the magnitude of the clutch load based on the characteristic lines La1 and La2, and sets the clutch protection flag FLb of the transfer clutch 24 based on the result of this determination. That is, as shown in FIG. 11, when the control system 70 calculates the clutch load to be "C1a", it determines that the clutch load belongs to a high load region exceeding the characteristic line La1, and sets the clutch protection flag FLb. When the control system 70 calculates the clutch load to be "C1b", it determines that the clutch load belongs to a low load region below the characteristic line La2, and cancels the setting of the clutch protection flag FLb. Furthermore, when the control system 70 calculates the clutch load to be "C1c", that is, when it determines that the clutch load belongs to a medium load region below the characteristic line La1 and above the characteristic line La2, if this situation continues for a predetermined time, it sets the clutch protection flag FLb.

[0046] That is, when the transfer clutch 24 has an appropriate amount of oil, the control system 70 determines the magnitude of the differential rotation speed ΔN based on the rotation threshold value obtained from the characteristic lines La1 and La2, and sets the clutch protection flag FLb of the transfer clutch 24 based on the determination result. For example, as shown in Fig. 13, when the engagement command torque Tt is "Tx", the control system 70 calculates the rotation threshold values ​​(first threshold values) Na1 and Na2 according to the characteristic lines La1 and La2. Then, when the differential rotation speed ΔN exceeds the rotation threshold value Na1, the control system 70 determines that the clutch load belongs to a high load region exceeding the characteristic line La1, and sets the clutch protection flag FLb.

[0047] Furthermore, when the differential rotation ΔN is below the rotation threshold value Na2, the control system 70 determines that the clutch load is in a low load region below the characteristic line La2, and cancels the setting of the clutch protection flag FLb. Furthermore, when the differential rotation ΔN is below the rotation threshold value Na1 and above the rotation threshold value Na2, the control system 70 determines that the clutch load is in a medium load region below the characteristic line La1 and above the characteristic line La2, and sets the clutch protection flag FLb if this situation continues for a predetermined time.

[0048] <Clutch load judgment: Low oil condition> As shown in FIG. 9 and FIG. 10, when the control system 70 determines in step S30 that the appropriate oil amount flag FLa is not set, that is, when the control system 70 determines that the transfer clutch 24 is in an oil shortage state, the control system 70 proceeds to step S41. As shown in FIG. 10, in step S41, the control system 70 calculates the clutch load based on the differential rotation ΔN of the transfer clutch 24 and the engagement command torque Tt. In addition, when the control system 70 calculates the clutch load in step S41, the control system 70 proceeds to step S42 and determines the region to which the clutch load belongs based on the characteristic lines Lb1 and Lb2. Here, as shown in FIG. 12, the region above the characteristic line Lb1 is the high load region, and the region below the characteristic line Lb2 lower than the characteristic line Lb1 is the low load region. In addition, the region below the characteristic line Lb1 and above the characteristic line Lb2 is the medium load region. Note that the characteristic line Lb1 is set lower than the above-mentioned characteristic line La1, and the characteristic line Lb2 is set lower than the above-mentioned characteristic line La2.

[0049] As shown in Fig. 10, the control system 70 proceeds to step S43 and determines whether or not the clutch load is in the medium load region. If the control system 70 determines in step S43 that the clutch load is in the medium load region, the control system 70 proceeds to step S44 and determines whether or not a predetermined determination time has elapsed. If the control system 70 determines in step S44 that the determination time has elapsed, that is, if the medium load region has continued over the determination time, the control system 70 proceeds to step S45 and sets the clutch protection flag FLb (FLb = 1). On the other hand, if the control system 70 determines in step S44 that the determination time has not elapsed, the control system 70 proceeds to step S41 and calculates the clutch load again based on the differential rotation ΔN and the engagement command torque Tt.

[0050] If the control system 70 determines in step S43 that the load is not in the medium load range, the process proceeds to step S46, where it determines whether the clutch load is in the high load range. If the control system 70 determines in step S46 that the load is in the high load range, the process proceeds to step S45, where it sets the clutch protection flag FLb (FLb=1). On the other hand, if the control system 70 determines in step S46 that the load is not in the high load range, that is, if the clutch load is in the low load range, the process proceeds to step S46, where it cancels the setting of the clutch protection flag FLb (FLb=0).

[0051] In this way, when the transfer clutch 24 is in an oil shortage state, the control system 70 determines the magnitude of the clutch load based on the characteristic lines Lb1 and Lb2, and sets the clutch protection flag FLb based on this determination result. That is, as shown in FIG. 12, when the control system 70 calculates the clutch load to be "C2a", it determines that the clutch load belongs to a high load region exceeding the characteristic line Lb1, and sets the clutch protection flag FLb. When the control system 70 calculates the clutch load to be "C2b", it determines that the clutch load belongs to a low load region below the characteristic line Lb2, and cancels the setting of the clutch protection flag FLb. Furthermore, when the control system 70 calculates the clutch load to be "C2c", that is, when it determines that the clutch load belongs to a medium load region below the characteristic line Lb1 and above the characteristic line Lb2, if this situation continues for a predetermined time, it sets the clutch protection flag FLb.

[0052] That is, when the transfer clutch 24 is in an oil shortage state, the control system 70 determines the magnitude of the differential rotation ΔN based on the rotation threshold value obtained from the characteristic lines Lb1 and Lb2, and sets the clutch protection flag FLb of the transfer clutch 24 based on this determination result. For example, as shown in Fig. 13, when the engagement command torque Tt is "Tx", the control system 70 calculates the rotation threshold values ​​(second threshold values) Nb1 and Nb2 according to the characteristic lines Lb1 and Lb2. Then, when the differential rotation ΔN exceeds the rotation threshold value Nb1, the control system 70 determines that the clutch load belongs to a high load region exceeding the characteristic line Lb1, and sets the clutch protection flag FLb.

[0053] Furthermore, when the differential rotation ΔN is below the rotation threshold value Nb2, the control system 70 determines that the clutch load belongs to a low load region below the characteristic line Lb2, and releases the setting of the clutch protection flag FLb. Furthermore, when the differential rotation ΔN is below the rotation threshold value Nb1 and above the rotation threshold value Nb2, the control system 70 determines that the clutch load belongs to a medium load region below the characteristic line Lb1 and above the characteristic line Lb2, and sets the clutch protection flag FLb when this situation continues for a predetermined time. Note that, as shown in FIG. 13, when the engagement command torque Tt is "Tx", the rotation threshold value Nb1 is set smaller than the rotation threshold value Nb1, and the rotation threshold value Nb2 is set smaller than the rotation threshold value Nb2.

[0054] <Clutch protection control> Next, the clutch protection control for suppressing the slip state of the transfer clutch 24 will be described. Fig. 14 is a flowchart showing an example of the execution procedure of the clutch protection control. As shown in Fig. 14, the control system 70 proceeds to step S50 and determines whether or not the clutch protection flag FLb is set, that is, whether or not it is necessary to protect the transfer clutch 24 from heat generation, etc. If the control system 70 determines in step S30 that it is necessary to protect the transfer clutch 24, it proceeds to step S51 and increases the engagement command torque Tt of the transfer clutch 24 by a predetermined amount.

[0055] When the control system 70 increases the engagement command torque Tt in step S51, the process proceeds to step S52, where it determines whether or not the slip state of the transfer clutch 24 has been eliminated, that is, whether or not the differential rotation ΔN of the transfer clutch 24 has been eliminated. When the control system 70 determines in step S52 that the slip state has been eliminated, the excessive heat generation, etc. of the transfer clutch 24 is eliminated, and so the control system 70 exits the routine.

[0056] If the control system 70 determines in step S52 that the slip state has not been resolved, the process proceeds to step S53, where it determines whether the current supplied to the electromagnetic drive unit 47 has reached a maximum value. If the control system 70 determines in step S53 that the current supplied has not reached the maximum value, the process proceeds again to step S51, where it increases the engagement command torque Tt of the transfer clutch 24 by a predetermined amount. Note that the situation in which the current supplied reaches the maximum value in step S53 refers to the situation in which the engagement torque of the transfer clutch 24 has increased to the maximum value.

[0057] When the control system 70 determines in step S53 that the energizing current has reached the maximum value, the process proceeds to step S54, where it controls the engine 12 and the motor generator 13 to reduce the input torque to the transfer clutch 24. In step S54, the control system 70 reduces the input torque to the transfer clutch 24 by reducing at least one of the engine torque and the motor torque.

[0058] When the control system 70 reduces the input torque of the transfer clutch 24 in step S54, the process proceeds to step S55 to determine whether or not the slip state of the transfer clutch 24 has been eliminated, that is, whether or not the differential rotation ΔN of the transfer clutch 24 has been eliminated. When the control system 70 determines in step S55 that the slip state has been eliminated, the excessive heat generation, etc. of the transfer clutch 24 is eliminated, and the control system 70 exits the routine.

[0059] <Summary> As described above, when the lubrication state of the transfer clutch 24 is in an appropriate oil amount state, if the differential rotation (slip amount) ΔN of the transfer clutch 24 exceeds the first threshold value obtained from the characteristic lines La1 and La2, the control system 70 executes clutch protection control to suppress the slip state of the transfer clutch 24. Also, when the lubrication state of the transfer clutch 24 is in an oil shortage state, if the differential rotation ΔN of the transfer clutch 24 exceeds the second threshold value obtained from the characteristic lines Lb1 and Lb2, the control system 70 executes clutch protection control to suppress the slip state of the transfer clutch 24. Also, the characteristic line Lb1 is set smaller than the characteristic line La1, and the characteristic line Lb2 is set smaller than the characteristic line La2. As a result, when the transfer clutch 24 is in an oil shortage state, the clutch protection control can be executed at an early timing, and the transfer clutch 24 can be appropriately protected.

[0060] In the example shown in FIG. 11, when the transfer clutch 24 is in an appropriate oil amount state, two characteristic lines La1 and La2 are used, but this is not limited thereto, and only one characteristic line La1 may be used. Similarly, in the example shown in FIG. 12, when the transfer clutch 24 is in an oil shortage state, two characteristic lines Lb1 and Lb2 are used, but this is not limited thereto, and only one characteristic line Lb1 may be used. That is, when the transfer clutch 24 is in an appropriate oil amount state, the control system 70 executes clutch protection control when the differential rotation ΔN of the transfer clutch 24 exceeds a first threshold value obtained from the characteristic line La1. Also, when the transfer clutch 24 is in an oil shortage state, the control system 70 executes clutch protection control when the differential rotation ΔN of the transfer clutch 24 exceeds a second threshold value obtained from the characteristic line Lb1.

[0061] As shown in Fig. 11, the first threshold value obtained from the characteristic lines La1 and La2 is set smaller as the engagement command torque Tt of the transfer clutch 24 increases, i.e., as the engagement torque of the transfer clutch 24 increases. Also, as shown in Fig. 12, the second threshold value obtained from the characteristic lines Lb1 and Lb2 is set smaller as the engagement command torque Tt of the transfer clutch 24 increases, i.e., as the engagement torque of the transfer clutch 24 increases. This allows the clutch protection control to be executed at an appropriate timing.

[0062] In the example shown in FIG. 11, the first threshold value obtained from the characteristic lines La1 and La2 is changed according to the engagement command torque Tt, but the present invention is not limited to this. In other words, the control system 70 may execute the clutch protection control when the differential rotation ΔN exceeds the first threshold value, which is a fixed value, in a situation where the transfer clutch 24 is in an appropriate oil amount state. Similarly, in the example shown in FIG. 12, the second threshold value obtained from the characteristic lines Lb1 and Lb2 is changed according to the engagement command torque Tt, but the present invention is not limited to this. In other words, the control system 70 may execute the clutch protection control when the differential rotation ΔN exceeds the second threshold value, which is a fixed value, in a situation where the transfer clutch 24 is in an oil shortage state.

[0063] The present disclosure is not limited to the above-described embodiment, and may be modified in various ways without departing from the spirit of the present disclosure. In the above description, the control system 70 is configured by a plurality of control units 71, 72, 73, and 80, but the present disclosure is not limited to this. For example, the control system 70 may be configured by one control unit. In addition, the illustrated power unit 14 is a power unit 14 for a hybrid vehicle having an engine 12 and a motor generator 13 as power sources, but the present disclosure is not limited to this. It may be a power unit having only the engine 12 as a power source, or a power unit for an electric vehicle having only the motor generator 13 as a power source.

[0064] In the above description, the transfer clutch 24 is used as a friction clutch that controls the torque distribution ratio between the front wheels 20 and the rear wheels 18, but this is not limited thereto. For example, a limited differential clutch provided in a center differential mechanism may be used as a friction clutch that controls the torque distribution ratio between the front wheels 20 and the rear wheels 18. In the above description, the transfer clutch 24 is controlled by the electromagnetic drive unit 47, but this is not limited thereto. For example, the transfer clutch 24 may be controlled by a hydraulically controlled piston. In the illustrated example, the transfer clutch 24 is a multiple plate clutch, but this is not limited thereto, and a single plate clutch may be used as the transfer clutch 24.

[0065] In the above description, the clutch protection control is performed by increasing the fastening torque of the transfer clutch 24 to eliminate slippage, and by decreasing the input torque of the transfer clutch 24 to eliminate slippage, but this is not limited to the above. For example, the clutch protection control may be performed by decreasing the fastening torque of the transfer clutch 24 to release the transfer clutch 24 to eliminate slippage. In addition, it goes without saying that the start switch 90 is not limited to a physical switch that operates mechanically, and a virtual switch displayed on a touch panel or the like may be used as the start switch 90. [Explanation of symbols]

[0066] 10 Vehicle drive device 11 Vehicles 12 Engine (power source) 13 Motor generator (power source) 18 Rear wheels (drive wheels) 20 Front wheels (drive wheels) 24 Transfer clutch (friction clutch) 28 Speed ​​change input shaft (rotating shaft) 40,41 Power transmission path 50 Oil supply system (lubrication system) 51 Oil pump 54 Rotor 58 Crankshaft 70 Control System 90 Start switch 100 processors 101 Main memory (memory) ΔN Differential rotation (slip amount) Na1,Na2 rotation threshold (first threshold) Nb1,Nb2 Rotation threshold (second threshold) Tb1 Leakage time (supply stop time) Xb1 Time Threshold

Claims

1. A vehicle drive device provided in a vehicle, a friction clutch provided in a power transmission path connecting a power source and drive wheels, the friction clutch controlling a torque distribution ratio of the drive wheels; a lubrication system including an oil pump for discharging oil and supplying the oil to the friction clutch; A control system including a processor and a memory communicatively connected to each other, the control system executing clutch protection control for suppressing a slip state of the friction clutch; having The lubrication state of the friction clutch includes a first lubrication state and a second lubrication state in which the amount of oil is less than that of the first lubrication state, The control system includes: In a situation where the friction clutch is in the first lubrication state, when a slip amount of the friction clutch exceeds a first threshold value, the clutch protection control is executed; In a situation where the friction clutch is in the second lubrication state, the clutch protection control is executed when a slip amount of the friction clutch exceeds a second threshold value that is smaller than the first threshold value. A drive unit for a vehicle.

2. 2. The vehicle drive device according to claim 1, The control system determines that the friction clutch is in the second lubrication state when a time during which the supply of oil to the friction clutch is stopped exceeds a time threshold. A drive unit for a vehicle.

3. 3. The vehicle drive device according to claim 2, The supply stop time is the time from when the driver turns off the start switch of the control system to when the driver turns it on. A drive unit for a vehicle.

4. 2. The vehicle drive device according to claim 1, As the engagement torque of the friction clutch increases, the first threshold value and the second threshold value are set to be smaller. A drive unit for a vehicle.

5. 2. The vehicle drive device according to claim 1, The rotor of the oil pump is connected to both a crankshaft of the engine which is the power source and a rotating shaft which constitutes the power transmission path, The lubrication system stops supplying oil to the friction clutch when the engine is stopped and the driving speed is below a speed threshold. A drive unit for a vehicle.

Images