JP6594274B2 - Vehicle driving force control device - Google Patents

Description

  The present invention relates to a vehicle driving force control device including a hydraulic clutch as a driving force distribution device and control means for controlling hydraulic pressure supplied to the hydraulic clutch.

  Conventionally, a front differential (rear differential) mechanism and a rear differential (rear differential) mechanism are connected as one of the electronically controlled four-wheel drive systems that switch between two-wheel drive (2WD) and four-wheel drive (4WD) states. There is a four-wheel drive system that includes a front-rear torque distribution clutch provided in the middle of a propeller shaft and a hydraulic control device that controls the hydraulic pressure of the clutch. Further, as a hydraulic control device for such a four-wheel drive system, the hydraulic pressure (oil) for driving the clutch is supplied by an electric oil pump through a check valve, and the supplied hydraulic pressure is sealed by a solenoid valve. There is known a hydraulic control device of a hydraulic enclosure type that maintains the fastening state (see, for example, Patent Document 1).

  In addition, after a predetermined hydraulic pressure (clutch pressure) is sealed in the clutch, the clutch engagement state, that is, the clutch pressing force is changed by controlling the opening and closing of a solenoid valve provided between the clutch and the check valve. Thus, the distribution of torque transmitted to the front and rear wheels can be changed. Therefore, once the vehicle transitions to the 4WD state, the clutch engagement state (clutch pressing force) is maintained as long as the solenoid valve is closed. Therefore, even if the electric oil pump motor does not continue to operate, the 4WD state is maintained. It is possible to continue the state. This is an advantage of the hydraulically enclosed four-wheel drive system from the viewpoint of reducing motor frequency and saving power.

  However, the torque distribution transmitted to the front and rear wheels cannot be accurately controlled only by opening / closing control of the solenoid valve. Therefore, in order to achieve high 4WD performance, only the low torque region, which requires particularly high accuracy, is made hydraulically open type control, so that the motor frequency that is also a merit of the hydraulically enclosed four-wheel drive system without impairing the 4WD performance. Suppression can be achieved.

  The command value of the front and rear wheel transmission torque necessary for 4WD control is called command torque. The actually generated transmission torque accurately follows the command torque leads to an improvement in 4WD performance. Here, the command torque can be converted into the command oil pressure by measuring the relationship between the transmission torque and the oil pressure in advance. That is, the control target is that the hydraulic pressure that is actually generated accurately follows the command hydraulic pressure (hereinafter also referred to as “hydraulic accuracy”).

JP 2013-067326 A

  By the way, in the hydraulic control apparatus of the above-described hydraulic oil enclosed type, the hydraulic pressure-torque characteristics on the pressure side (rising side) when the hydraulic oil is sealed and pressurized in the piston chamber (oil passage) of the clutch, and the piston chamber The oil pressure command value (input oil pressure) for generating the same torque in the clutch differs from the pressure reducing side (lowering side) hydraulic pressure-torque characteristics when the hydraulic oil is discharged to reduce pressure. It has been known.

  In addition, as another characteristic of the hydraulic oil control device of the above-described hydraulic oil enclosed type, it is also understood that the hydraulic hysteresis characteristic changes depending on the torque input time (that is, the operation time of the motor when torque is transmitted by the clutch). ing. Specifically, if the torque input time is shortened (accelerated response) for a certain command torque, the hydraulic hysteresis characteristics on the pressurization side and pressure reduction side are increased, and the torque input time is lengthened (responsiveness is delayed). There is a tendency that the hydraulic hysteresis characteristics on the pressure side and the pressure reduction side become smaller.

  However, the fluctuation of the hydraulic hysteresis characteristic due to the torque input time of the clutch as described above has a great influence on the relationship between the transmission torque and the hydraulic pressure. For this reason, there has been a problem that the accuracy (torque accuracy) of the torque transmitted by the torque transmission device cannot be sufficiently increased due to the fluctuation of the hydraulic hysteresis characteristic due to the torque input time.

  The present invention has been made in view of the above-described problems, and an object of the present invention is to provide a vehicle driving force control device including a hydraulic control device that controls the hydraulic pressure of a piston chamber of a clutch as a driving force distribution device. Driving the vehicle can effectively increase the accuracy of torque transmitted by the clutch by appropriately correcting the change due to the torque input time of the hydraulic hysteresis characteristics that occur between the pressure side and the pressure reduction side of the piston chamber. It is to provide a force control device.

  In order to achieve the above object, a vehicle driving force control apparatus according to the present invention uses driving force from a driving source (engine 3) of a vehicle as driving wheels (first driving wheels W1, W2 and second driving wheels W3, W4). ), A clutch (10) as a driving force distribution device installed in the driving force transmission path (20), and a piston (12) that presses and engages the clutch (10) A piston chamber (15) for generating hydraulic pressure, an oil pump (35) for supplying hydraulic oil to the piston chamber (15), a motor (37) for driving the oil pump (35), and an oil pump Control means (4WD • ECU 50) for performing control to determine the hydraulic pressure command value for (35) and the drive current of the motor (37) based on the hydraulic pressure command value, and the control means (50) includes the clutch (10). With torque And performing control to change the hydraulic pressure command value to the oil pump (35) in accordance with the operating time of the motor (37) when transmitting.

  According to the vehicle driving force control apparatus of the present invention, the control means performs control to change the hydraulic pressure command value for the oil pump in accordance with the operation time of the motor when torque is transmitted by the clutch. The influence of fluctuations in the hydraulic hysteresis characteristics due to the torque input time can be reduced. That is, when changing the hydraulic pressure command value, it is possible to change the hydraulic pressure command value so as to suppress the influence of fluctuations in the hydraulic hysteresis characteristic. As a result, the accuracy of the torque transmitted to the drive wheels by the clutch as the drive force distribution device can be effectively increased, so that the drive force control device can more appropriately control the drive force of the vehicle.

  The vehicle driving force control device also includes a hydraulic oil sealing valve (check valve 39) for sealing hydraulic oil in an oil passage (49) leading from the oil pump (35) to the piston chamber (15), and an operation. A hydraulic circuit (30) comprising an on-off valve (solenoid 43) for opening and closing an oil passage (39) between the oil-filled valve (39) and the piston chamber (15) is provided, and control means (50) When the piston chamber (15) is pressurized, the piston chamber (15) is brought to the target hydraulic pressure based on the pressure side characteristics obtained by closing the on-off valve (43) and driving the oil pump (35). When the pressure in the piston chamber (15) is reduced, the oil pump (35) is prohibited from being driven and the on-off valve (43) is opened. 15) is controlled so that it becomes the target oil pressure. In terms of performance, the hydraulic pressure command value is changed to a smaller value as the operating time of the motor (37) becomes longer. On the other hand, in the decompression side characteristic, the hydraulic pressure command value is set to a larger value as the operating time of the motor (37) becomes longer. It may be changed.

  In the enclosed hydraulic circuit as described above, in the pressure side characteristic, the hydraulic pressure for outputting the same torque becomes smaller as the motor operating time becomes longer, and in the pressure reducing side characteristic, the motor operating time becomes longer. There is a tendency that the hydraulic pressure for outputting the same torque becomes a large value. Therefore, in the driving force control device of the present invention, in the pressure side characteristic, the hydraulic pressure command value is changed to a smaller value as the motor operating time becomes longer, and in the pressure reduction side characteristic, the hydraulic pressure command value becomes longer as the motor operating time becomes longer. Change the value to a smaller value. Thereby, it is possible to suppress the influence of fluctuations in the hydraulic hysteresis characteristics due to the torque input time in both the pressure side characteristics and the pressure reduction side characteristics.

  Further, in this vehicle driving force control device, the first hydraulic pressure value, which is the value of the hydraulic pressure with respect to the predetermined torque when the operating time of the motor measured in advance is not more than a predetermined value, and the predetermined torque when the operating time of the motor is not less than the specified value The hydraulic pressure command value for a predetermined torque may be changed between the first hydraulic pressure value and the second hydraulic pressure value according to the operating time of the motor. Furthermore, in this case, a linear interpolation value between the first hydraulic pressure value and the second hydraulic pressure value may be output as the hydraulic pressure command value. In addition, the case where the operation time of the motor here is a predetermined value or less is, for example, the case where the operation time of the motor in the embodiment of the present invention is the shortest, and the case where the operation time of the motor is a predetermined value or more is, for example, This is a case where the operation time of the motor in the embodiment of the present invention is the longest.

  According to this configuration, the influence of the change in the hydraulic hysteresis characteristic due to the torque input time can be suppressed with a simpler control, and the torque accuracy of the clutch can be improved, so that the driving force of the vehicle can be controlled more appropriately. Will be able to.

  In one embodiment of the vehicle driving force control apparatus according to the present invention, the driving force transmission path (30) transmits the driving force from the driving source (3) to the first driving wheels (W1, W2). And a path for transmitting driving force from the driving source (3) to the second driving wheels (W3, W4), and the clutch (10) is connected from the driving source (3) to the second driving wheels (W3, W4). The driving force distribution device may be provided in a path for transmitting the driving force.

  According to this configuration, the accuracy of the torque transmitted to the second drive wheel of the vehicle can be improved, so that the distribution of the drive force between the first drive wheel and the second drive wheel of the vehicle can be controlled more appropriately. Will be able to. Therefore, the running performance of the vehicle can be improved more effectively.

  According to the control device for a four-wheel drive vehicle according to the present invention, in the vehicle drive force control device including the hydraulic control device that controls the hydraulic pressure of the clutch serving as the drive force distribution device, The accuracy of the torque transmitted by the clutch can be effectively increased by appropriately correcting the change in the hydraulic hysteresis characteristic generated during the time depending on the torque input time.

It is explanatory drawing which shows schematic structure of the four-wheel drive vehicle provided with the control apparatus which concerns on one Embodiment of this invention. It is a hydraulic circuit diagram which shows the detailed structure of a hydraulic circuit. It is a block diagram which shows the main structures of the control apparatus which concerns on this embodiment. It is a block diagram which shows the structure of the motor PWM control block which concerns on this embodiment. It is a hydraulic circuit diagram showing the state of hydraulic oil in the hydraulic control of the piston chamber, (a) is the state of the hydraulic oil at the time of pressurization, (b) is the state of the hydraulic oil at the time of holding the hydraulic pressure, (c), It is a figure which shows the state of the hydraulic oil at the time of pressure reduction. It is a timing chart which shows the operation / stop state of the motor (oil pump) in the hydraulic control of the piston chamber, the open / close state of the solenoid valve, and the actual oil pressure. It is a graph which shows the relationship (hydraulic-torque characteristic) of the oil_pressure | hydraulic and torque in the oil pressure control of a piston chamber. It is a graph which shows the change of the oil pressure-torque characteristic with respect to the torque input time (motor operating time) of a clutch.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

  FIG. 1 is an explanatory diagram showing a schematic configuration of a four-wheel drive vehicle including a control device according to an embodiment of the present invention. A four-wheel drive vehicle 1 shown in the figure has an engine (drive source) 3 mounted horizontally in the front portion of the vehicle, an automatic transmission 4 installed integrally with the engine 3, and a driving force from the engine 3. A driving force transmission path 20 for transmitting to the front wheels W1, W2 and the rear wheels W3, W4 is provided. Hereinafter, each configuration will be described in more detail.

  An output shaft (not shown) of the engine 3 is connected to a first drive wheel (main drive) via an automatic transmission 4, a front differential (hereinafter referred to as “front differential”) 5, and left and right front drive shafts 6, 6. Are connected to the left and right front wheels W1, W2. Further, the output shaft of the engine 3 is connected to the second through an automatic transmission 4, a front differential 5, a propeller shaft 7, a rear differential unit (hereinafter referred to as “rear differential unit”) 8, and left and right rear drive shafts 9, 9. It is connected to left and right rear wheels W3, W4 which are drive wheels (sub drive wheels).

  The rear differential unit 8 is connected with a rear differential (hereinafter referred to as “rear differential”) 19 for distributing drive force to the left and right rear drive shafts 9 and 9 and a drive force transmission path from the propeller shaft 7 to the rear differential 19. A front-rear torque distribution clutch 10 for cutting is provided. The front-rear torque distribution clutch 10 is a hydraulically driven clutch and is a driving force distribution device for controlling the driving force distributed to the rear wheels W3, W4 in the driving force transmission path 20. Also, a hydraulic circuit 30 for supplying hydraulic oil to the front-rear torque distribution clutch 10 and a 4WD • ECU (hereinafter simply referred to as “ECU”) as control means for controlling the hydraulic pressure supplied by the hydraulic circuit 30. 50. The ECU 50 is configured by a microcomputer or the like.

  The ECU 50 controls the driving force distributed to the rear wheels W3 and W4 by the front and rear torque distribution clutch (hereinafter simply referred to as “clutch”) 10 by controlling the hydraulic pressure supplied by the hydraulic circuit 30. Thus, drive control is performed in which the front wheels W1 and W2 are the first drive wheels and the rear wheels W3 and W4 are the second drive wheels.

  That is, when the clutch 10 is released (disconnected), the rotation of the propeller shaft 7 is not transmitted to the rear differential 19 side, and all the torque of the engine 3 is transmitted to the front wheels W1, W2, thereby driving the front wheels (2WD). It becomes a state. On the other hand, when the clutch 10 is engaged (connected), the rotation of the propeller shaft 7 is transmitted to the rear differential 19 side, whereby the torque of the engine 3 is distributed to both the front wheels W1, W2 and the rear wheels W3, W4. To a four-wheel drive (4WD) state. The ECU 50 calculates the driving force distributed to the rear wheels W3 and W4 and the corresponding hydraulic pressure supply amount to the clutch 10 based on detection by various detection means (not shown) for detecting the running state of the vehicle. In addition, a drive signal based on the calculation result is output to the clutch 10. Thereby, the fastening force of the clutch 10 is controlled, and the driving force distributed to the rear wheels W3, W4 is controlled.

  FIG. 2 is a hydraulic circuit diagram showing a detailed configuration of the hydraulic circuit 30. The hydraulic circuit 30 shown in FIG. 1 includes an oil pump 35 that sucks and feeds hydraulic oil stored in the oil tank 31 via a strainer 33, a motor 37 that drives the oil pump 35, and an oil pump 35 to the clutch 10. And an oil passage 40 communicating with the piston chamber 15.

  The clutch 10 includes a cylinder housing 11 and a piston 12 that presses the plurality of friction materials 13 stacked by moving forward and backward in the cylinder housing 11. A piston chamber 15 into which hydraulic oil is introduced between the piston 12 and the piston 12 is defined in the cylinder housing 11. The piston 12 is disposed to face one end of the plurality of friction materials 13 in the stacking direction. Therefore, the piston 10 presses the friction material 13 in the stacking direction by the hydraulic pressure of the hydraulic oil (oil) supplied to the piston chamber 15 so that the clutch 10 is engaged with a predetermined engagement pressure.

  A check valve 39, a relief valve 41, a solenoid valve (open / close valve) 43, and a hydraulic pressure sensor 45 are installed in this order in an oil passage 49 that communicates from the oil pump 35 to the piston chamber 15. The check valve 39 circulates hydraulic oil from the oil pump 35 side toward the piston chamber 15 side, but is configured to prevent the hydraulic oil from flowing in the opposite direction. Thereby, the hydraulic oil sent to the downstream side of the check valve 39 by the drive of the oil pump 35 is referred to as an oil passage (hereinafter referred to as “enclosed oil passage”) between the check valve 39 and the piston chamber 15. Can be contained in 49). The oil passage 49 provided with the check valve 39 and the oil pump 35 constitutes a hydraulic pressure hydraulic circuit 30. In the present embodiment, the check valve 39 is a hydraulic oil sealing valve for sealing hydraulic oil in an oil passage 49 that leads from the oil pump 35 to the piston chamber 15.

  The relief valve 41 is configured to open the oil pressure in the oil passage 49 by opening when the pressure in the oil passage 49 between the check valve 39 and the piston chamber 15 exceeds a predetermined threshold and abnormally rises. It is a good valve. The hydraulic oil discharged from the relief valve 41 is returned to the oil tank 31. The solenoid valve 43 is an on / off type on-off valve and can be controlled to be opened / closed (On / Off) based on a command from the ECU 50 to control the opening / closing of the oil passage 49. Thereby, the hydraulic pressure of the piston chamber 15 can be controlled. The hydraulic oil discharged from the oil passage 49 when the solenoid valve 43 is opened is returned to the oil tank 31. The oil pressure sensor 45 is oil pressure detecting means for detecting the oil pressure in the oil passage 49 and the piston chamber 15, and the detected value is sent to the ECU 50. The piston chamber 15 communicates with the accumulator 18. The accumulator 18 has a function of suppressing a rapid change in hydraulic pressure in the piston chamber 15 and the oil passage 49 and a pulsation of hydraulic pressure. Further, an oil temperature sensor 47 for detecting the temperature of the hydraulic oil is provided in the oil tank 31. The detection value of the oil temperature sensor 47 is sent to the ECU 50.

  The oil pump 35 is a positive displacement pump, for example, an internal gear pump. Oil is supplied from the oil pump 35 to the oil passage 49 and the piston chamber 15 by the PWM control (duty control) of the motor 37 based on a command from the ECU 50. As a result, the piston pressure required to engage the clutch 10 is ensured.

  FIG. 3 is a block diagram showing a main configuration of the 4WD • ECU (control means) 50. In the drive torque calculation block 51, the drive torque (estimated drive force) required for the vehicle 1 is calculated according to the travel conditions of the vehicle 1 (torque of the engine 3, selected gear stage of the automatic transmission 4, shift position, etc.). .

  In the control torque calculation block 52, the basic torque control (basic power distribution control to the front and rear wheels W1 to W4) block 521, the LSD control block 522, the uphill control block 523, etc., according to various control factors, the drive torque. Is distributed to the front and rear wheels, and the command torque of the front and rear torque distribution clutch (driving force distribution device) 10 is calculated.

  In the command hydraulic pressure calculation block 53, the command hydraulic pressure PCMD for the clutch 10 is calculated according to the command torque. That is, the control target value calculation block 531 calculates the control target value for the clutch 10 (that is, the command hydraulic pressure PCMD) according to the command torque. Note that control for changing a hydraulic pressure command value for the oil pump 35 described later in the present embodiment is performed as part of control for calculating the command hydraulic pressure in the command hydraulic pressure calculation block 53.

  In the command hydraulic pressure calculation block 53, a control target value (that is, the command hydraulic pressure PCMD) for the 2WD conversion block 532 to be 2WD at the time of failure is calculated. In the normal time, the control target value calculated by the control target value calculation block 531 is output as the command hydraulic pressure PCMD, but in the case of a failure, the control target value calculated by the failure 2WD block 532 is output as the command hydraulic pressure PCMD.

  In the hydraulic pressure feedback control block 54, a target hydraulic pressure ΔP between the command hydraulic pressure PCMD and the actual hydraulic pressure PR (feedback signal from the hydraulic pressure sensor 45) given from the command hydraulic pressure calculation block 53 by the target hydraulic pressure calculation block 541 is compared with the target hydraulic pressure. (For example, within ± several%) is calculated. The motor 37 or the solenoid valve 43 is controlled according to the calculated target oil pressure (that is, the oil pressure difference ΔP).

  The motor PWM control block 542 generates a PWM drive command signal (target drive current) for the motor 37 according to the target hydraulic pressure (that is, the hydraulic pressure difference ΔP), and outputs it to a motor driver (not shown). The motor driver applies a drive voltage corresponding to the PWM drive command signal to the motor 37. The PWM drive command signal includes a feedback control amount (hereinafter referred to as “F / B control amount”) generated from the hydraulic pressure difference ΔP and a feedforward control amount (hereinafter referred to as “F / F control”) generated from the command hydraulic pressure PCMD. It is generated by adding “quantity”.

  In the solenoid ON / OFF control block 543, the solenoid valve 43 is turned on (closed) / off (opened) in accordance with the hydraulic pressure difference ΔP (target hydraulic pressure) between the command hydraulic pressure PCMD and the feedback signal (actual hydraulic pressure PR) from the hydraulic pressure sensor 45. ) Generate an instruction signal (target drive current) and output it to a solenoid driver (not shown). The solenoid driver applies a drive voltage corresponding to the ON / OFF instruction signal to the solenoid valve 43.

  FIG. 4 is a block diagram showing a configuration of the motor PWM control block 542 according to the present embodiment. In the figure, the command hydraulic pressure calculation block 53 and the target hydraulic pressure calculation block 541 are also illustrated.

  The motor PWM control block 542 determines a drive current for driving the motor 37 based on the hydraulic pressure difference ΔP output from the target hydraulic pressure calculation block 541 (hereinafter referred to as “F / B control block”) 542a. And a feedforward control block (hereinafter referred to as “F / F control block”) 542b for determining a drive current for driving the motor 37 based on the command hydraulic pressure PCMD, and an F / B control block 542a. The motor output gate (output unit) 542c adds the drive current (F / B control amount) and the drive current (F / F control amount) output from the F / F control block 542b.

  Here, the operation of the hydraulic oil filled hydraulic circuit 30 will be briefly described. FIG. 5 is a circuit diagram showing the state of the hydraulic oil in the hydraulic circuit 30 in the hydraulic control of the piston chamber 15, where (a) is the state of the hydraulic oil when pressurized, and (b) is the operation when holding the hydraulic pressure. Oil state, (c) is a diagram showing the state of hydraulic oil during decompression. FIG. 6 is a timing chart showing the operation / stop state of the motor 37 (oil pump 35), the open / close state of the solenoid valve 43, and changes in the actual oil pressure in the hydraulic control of the piston chamber 15.

  Here, first, the operation of the hydraulic circuit 30 when the vehicle 1 transitions from the 2WD state to the 4WD state will be described. As shown in FIG. 6A, the ECU 50 energizes the motor 37, operates the oil pump 35, and injects oil into the oil passage 49. At the same time, the ECU 50 energizes the solenoid valve 43 to close it. Since the check valve 39 allows oil to pass only in the direction from the oil pump 35 to the oil passage 49, the oil is enclosed in the oil passage 49.

  When oil is sealed in the oil passage 49, the oil pressure in the oil passage 49 increases, and a pressure is generated that pushes the piston 12 to the left in the figure. When the piston 12 is pushed, the friction material 13 is pushed, the clutch 10 is fastened, and the 4WD state is set.

  The relationship between the torque desired to be distributed to the rear wheels W3 and W4 and the hydraulic pressure value in the oil passage 49 is modeled in advance, and the hydraulic pressure value in the oil passage 49 corresponding to the required torque to be distributed to the rear wheels W3 and W4. Is known. Therefore, the ECU 50 measures the oil pressure value in the oil passage 49 using the oil pressure sensor 45, and the oil pressure value in the oil passage 49 corresponds to the torque to be distributed to the rear wheels W3, W4 (= target oil pressure). ), The operation of the motor 37 and the closed state of the solenoid valve 43 are continued.

  When the oil pressure value in the oil passage 49 reaches the target oil pressure, the ECU 50 stops the operation of the motor 37 while the solenoid valve 43 is kept closed (FIG. 5B). In this way, the ECU 50 maintains the oil pressure in the oil passage 49 and continues the 4WD state of the vehicle 1 for a necessary time. When a higher target oil pressure is set, the ECU 50 further operates the motor 37 to pressurize the oil passage 49.

  Next, the operation of the hydraulic circuit 30 when the vehicle 1 transitions from the 4WD state to the 2WD state will be described. As shown in FIG. 5C, the ECU 50 opens the solenoid valve 43 while the motor 37 is stopped. As a result, the oil in the oil passage 49 is drained through the solenoid valve 43, and the oil pressure in the oil passage 49 decreases.

  When the oil pressure in the oil passage 49 decreases, the pressure applied to the piston 12 also decreases, so the pressing force against the friction material 13 decreases and the amount of torque distribution to the rear wheels W3 and W4 decreases.

  When the oil pressure in the oil passage 49 decreases to a predetermined oil pressure corresponding to the 2WD state, the ECU 50 closes the solenoid valve 43. When a lower target oil pressure is set, the ECU 50 opens the solenoid valve 43 until the oil pressure in the oil passage 49 reaches the target oil pressure, and when the oil pressure in the oil passage 49 reaches the target oil pressure, the solenoid valve 43 is opened. 43 is closed.

  In the hydraulic circuit 30 of the present embodiment, as shown before the time TX in the timing chart of FIG. 6, the actual hydraulic pressure is stepped (stepped) by opening the solenoid valve 43 while the motor 37 is stopped. 6), the solenoid valve is opened while operating while gradually changing (decreasing or increasing) the rotational speed of the motor 37, as shown after time TX in FIG. Thus, it is possible to perform control to gradually change (decrease or increase) the actual oil pressure.

  FIG. 7 is a graph showing the relationship (hydraulic-torque characteristics) between the hydraulic pressure P and the torque T in the hydraulic control of the piston chamber 15. In the hydraulic control by the hydraulic control device 60 of the present embodiment, as the hydraulic characteristic of the hydraulic circuit 30, the pressurized side (rising side) hydraulic-torque characteristic applied when the piston chamber 15 is pressurized and the hydraulic circuit 30 are applied when the piston chamber 15 is depressurized. The pressure reducing side (lowering side) hydraulic pressure-torque characteristic is provided. In FIG. 7, the pressure side hydraulic pressure-torque characteristic is indicated by a thick line, and the pressure reduction side hydraulic pressure-torque characteristic is indicated by a thin line. When the piston chamber 15 is pressurized, the drive of the motor 37 (oil pump 35) is controlled (duty control) so that the piston chamber 15 becomes the target hydraulic pressure based on the pressure side hydraulic pressure-torque characteristics. Control. Then, after pressurizing until the piston chamber 15 reaches the target hydraulic pressure based on the pressurization side hydraulic pressure-torque characteristics, until the pressure reduction starts, the state where the hydraulic oil is sealed in the sealed oil passage 49 is maintained. The torque of the clutch 10 can be kept constant. On the other hand, when the pressure in the piston chamber 15 is reduced, the operation of the oil pump 35 is prohibited and the opening and closing of the solenoid valve 43 is controlled (duty control), so that the piston chamber 15 is set to the target based on the pressure reduction side hydraulic pressure-torque characteristics. Control to be hydraulic.

  FIG. 8 is a graph showing changes in the hydraulic-torque characteristics with respect to the operation time of the motor 37 (the torque input time of the clutch 10) when torque is transmitted by the clutch 10. In FIG. In the graph of the figure, the pressure side (upward side) hydraulic pressure-torque characteristic is indicated by a thick line, and the pressure reduction side (downward side) hydraulic pressure-torque characteristic is indicated by a thin line. Further, in each of the pressure side and the pressure reduction side, the characteristic when the operating time of the motor 37 is the longest is indicated by a solid line, the characteristic when the operating time of the motor 37 is the shortest is indicated by a two-dot chain line, and the operating time of the motor 37 is The characteristic in the case where is an intermediate value between the longest and shortest is indicated by a one-dot chain line.

  Actually, even if the torque is transmitted by operating the motor 37 for a time shorter than the “when the operation time of the motor 37 is the shortest” here, the relationship between the hydraulic pressure and the torque does not change any more. It has been confirmed. Therefore, the relationship between the hydraulic pressure and the torque in that case is referred to as the relationship “when the operation time of the motor 37 is the shortest”. Similarly, it is possible to operate the motor 37 for a time longer than the time of “when the operation time of the motor 37 is the longest” here, but the motor 37 is longer than the time of the longest. It has been confirmed that the relationship between the hydraulic pressure and the torque does not change any more when the torque is transmitted by operating the. Therefore, the relationship between the hydraulic pressure and the torque in that case is referred to as the relationship “when the operation time of the motor 37 is the longest”. The hydraulic value of “when the operation time of the motor 37 is the shortest” (two-dot chain line) in FIG. 8 corresponds to “the value of the hydraulic pressure with respect to a predetermined torque when the operation time of the motor is less than or equal to” in the present invention. 8, the hydraulic pressure value of “when the operation time of the motor 37 is the longest” (solid line) corresponds to “the value of the hydraulic pressure with respect to a predetermined torque when the operation time of the motor is not less than a predetermined value” of the present invention.

  As shown in the graph of FIG. 8, in the pressure side (upward side) hydraulic pressure-torque characteristics, the hydraulic pressure P for outputting the same torque T is lower as the operating time of the motor 37 when the torque is transmitted by the clutch 10 is longer. (Smaller). On the other hand, in the decompression side (downward side) hydraulic pressure-torque characteristics, the hydraulic pressure P for outputting the same torque T becomes higher (larger) as the operating time of the motor 37 is longer. Using this tendency, in the hydraulic control of the piston chamber 15 of the present embodiment, the same torque as the torque input time of the clutch 10 (operation time of the motor 37) becomes longer in the pressure side (upward side) hydraulic pressure-torque characteristics. The hydraulic pressure command value P0 for outputting T0 is changed to a smaller value, and the pressure reduction (lowering side) hydraulic pressure-torque characteristics are the same as the operating time of the motor 37 when the torque is transmitted by the clutch 10 becomes longer. The hydraulic pressure command value P1 for outputting the torque T1 is changed to a larger value. That is, the initial characteristic is a line (two-dot chain line) in which the operating time of the motor 37 is the shortest in both the pressure side (upward side) hydraulic pressure-torque characteristic and the pressure reduction side (downward side) hydraulic pressure-torque characteristic. Thereafter, when the operating time of the motor 37 becomes longer, the line gradually changes from the line during the input time (one-dot chain line) to the line with the longest input time (solid line) to the characteristic side with a longer input time.

  Specifically, each of the pressurization side (upward side) hydraulic pressure-torque characteristic and the pressure reduction side (downward side) hydraulic pressure-torque characteristic has two characteristics when the operation time of the motor 37 is shortest and longest. As described above, the two-dot chain line shown in FIG. 8 is the characteristic when it is the shortest, and the characteristic when the solid line is the longest. When the output determination of the motor 37 is equal to or greater than the threshold value, it is determined that the torque input of the clutch 10 is present, and the linear interpolation value between the case where the torque input time is the shortest and the case where the torque input is the longest is Output as command value. That is, by measuring two characteristics in the case where the response time is the shortest and the case where the response time is the longest in advance, and changing between these two characteristics depending on the operating time of the motor 37 corresponding to the torque input time, Try to determine the value. Thereby, the torque accuracy of the torque output from the clutch 10 can be improved effectively.

  As described above, in the vehicle driving force control apparatus according to the present embodiment, control is performed to change the hydraulic pressure command value for the oil pump 35 in accordance with the operating time of the motor 37 when torque is transmitted by the clutch 10. The hydraulic pressure command value can be changed so as to suppress the influence of the fluctuation of the hydraulic hysteresis characteristic due to the torque input time of the clutch 10 to a lesser extent. Thereby, the accuracy of the torque transmitted to the rear wheels (second drive wheels) W3, W4 of the vehicle 1 by the clutch 10 can be effectively improved, and the driving force of the vehicle 1 can be controlled more appropriately. It becomes a driving force control device that can.

  Further, in this driving force control device, when the piston chamber 15 is pressurized, the piston chamber 35 is controlled based on the pressure side characteristics obtained by closing the solenoid valve (open / close valve) 43 and driving the oil pump 35. When the pressure in the piston chamber 35 is reduced by controlling to the target hydraulic pressure, the piston chamber 35 is set to the target hydraulic pressure based on the pressure-reducing characteristics obtained by prohibiting the drive of the oil pump 35 and opening the solenoid valve 43. It is controlled to become. In the pressure side characteristic, the hydraulic pressure command value is changed to a smaller value as the operating time of the motor 37 becomes longer. In the pressure reducing side characteristic, the hydraulic pressure command value is set to a smaller value as the operating time of the motor 37 becomes longer. I try to change it.

  In the hydraulic pressure control device 60 of the clutch 10 having the hydraulic oil-filled hydraulic circuit 30 as in the present embodiment, the hydraulic pressure for outputting the same torque becomes smaller as the operating time of the motor 37 becomes longer in the pressure side characteristics. In the pressure-reducing characteristics, the hydraulic pressure for outputting the same torque tends to increase as the operating time of the motor 37 increases. Therefore, in the driving force control apparatus of the present embodiment, the hydraulic pressure command value is changed to a smaller value as the operating time of the motor 37 becomes longer in the pressure side characteristics, and the operating time of the motor 37 becomes longer in the pressure reducing characteristics. The hydraulic pressure command value is changed to a larger value. Thereby, it is possible to suppress the influence of the fluctuation of the hydraulic hysteresis characteristic due to the torque input time of the clutch 10 in both the pressure side characteristic and the pressure reduction side characteristic.

  Further, in the vehicle driving force control apparatus of the present embodiment, the value of the hydraulic pressure with respect to a predetermined torque when the operation time of the motor 37 measured in advance is the shortest (predetermined or less) (PT characteristic of the two-dot chain line in FIG. 8: A first hydraulic pressure value) and a hydraulic pressure value with respect to a predetermined torque when the operation time of the motor 37 is the longest (predetermined or greater) (solid line PT characteristic: second hydraulic pressure value in FIG. 8) The hydraulic pressure command value (P0 or P1) for a predetermined torque (T0 or T1) is changed between the first hydraulic pressure value and the second hydraulic pressure value according to the operating time. Furthermore, in this case, a linear interpolation value between the first hydraulic pressure value and the second hydraulic pressure value is output as the hydraulic pressure command value.

  According to this configuration, the influence of the fluctuation of the hydraulic hysteresis characteristic due to the torque input time of the clutch 10 can be suppressed with a simpler control, and the torque accuracy of the clutch 10 can be improved. In particular, the driving force distributed to the rear wheels (second driving wheels) W3 and W4 can be controlled more appropriately.

  Although the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments, and various modifications can be made within the scope of the technical idea described in the claims and the specification and drawings. Is possible. For example, the vehicle 1 of the above embodiment transmits the driving force of the engine (drive source) 3 to the front wheels W1 and W2 that are the first drive wheels of the vehicle 1 and the rear wheels W3 and W4 that are the second drive wheels. The clutch as the driving force distribution device according to the present invention is a wheel driving vehicle, and in this four wheel driving vehicle, the driving force from the engine (driving source) 3 is transmitted to the rear wheels W3 and W4 which are the second driving wheels. However, the present invention can be applied to a vehicle other than a four-wheel drive vehicle, and a driving force is transmitted to a drive wheel other than the second drive wheel. It is also possible to apply to a clutch provided in the path to be performed.

1 Vehicle (four-wheel drive vehicle)
3 Engine (drive source)
4 Automatic transmission 5 Front differential 6 Front drive shaft 7 Propeller shaft 8 Rear differential unit 9 Rear drive shaft 10 Front / rear torque distribution clutch (clutch)
19 Rear differential 11 Cylinder housing 12 Piston 13 Friction material 15 Piston chamber 18 Accumulator 20 Driving force transmission path 30 Hydraulic circuit 31 Oil tank 33 Strainer 35 Oil pump (electric oil pump)
37 Motor (pump motor)
39 Check valve (hydraulic oil sealing valve)
41 Relief valve 43 Solenoid valve (open / close valve)
45 Oil pressure sensor 47 Oil temperature sensor 49 Oil passage (filled oil passage)
50 4WD • ECU (control means)
W1, W2 Front wheel (first drive wheel)
W3, W4 Rear wheel (second drive wheel)

Claims (5)

A driving force transmission path for transmitting the driving force from the driving source of the vehicle to the driving wheels;
A clutch as a driving force distribution device installed in the driving force transmission path;
A piston chamber that generates hydraulic pressure for a piston that presses and engages the clutch;
An oil pump for supplying hydraulic oil to the piston chamber;
A motor for driving the oil pump;
Control means for performing control to determine a hydraulic pressure command value for the oil pump and a driving current of the motor based on the hydraulic pressure command value;
The vehicle driving force control device according to claim 1, wherein the control means performs control to change a hydraulic pressure command value for the oil pump in accordance with an operation time of the motor when torque is transmitted by the clutch. A hydraulic oil sealing valve for sealing hydraulic oil into an oil passage leading from the oil pump to the piston chamber; and an on-off valve for opening and closing the oil passage between the hydraulic oil sealing valve and the piston chamber. With a configured hydraulic circuit,
The control means, when pressurizing the piston chamber, controls the piston chamber to become a target hydraulic pressure based on a pressure side characteristic obtained by closing the on-off valve and driving the oil pump, When the pressure in the piston chamber is reduced, the oil pump is prohibited from being driven and controlled so that the piston chamber reaches a target hydraulic pressure based on the pressure-reducing side characteristic obtained by opening the on-off valve.
In the pressure side characteristic, the hydraulic pressure command value is changed to a smaller value as the operating time of the motor becomes longer. On the other hand, in the pressure reducing side characteristic, the hydraulic pressure command value becomes a larger value as the operating time of the motor becomes longer. The driving force control apparatus for a vehicle according to claim 1, wherein A first hydraulic pressure value that is a hydraulic pressure value with respect to a predetermined torque when the operating time of the motor is less than or equal to a predetermined value, and a second hydraulic pressure value with respect to the predetermined torque when the operating time of the motor is greater than or equal to a predetermined value With hydraulic value,
3. The vehicle driving force control according to claim 1, wherein a hydraulic pressure command value for the predetermined torque is changed between the first hydraulic pressure value and the second hydraulic pressure value in accordance with an operation time of the motor. apparatus.   4. The vehicle driving force control device according to claim 3, wherein a linear interpolation value between the first hydraulic pressure value and the second hydraulic pressure value is output as a hydraulic pressure command value for the predetermined torque. The driving force transmission path includes a path for transmitting driving force from the driving source to the first driving wheel, and a path for transmitting driving force from the driving source to the second driving wheel.
5. The vehicle drive according to claim 1, wherein the clutch is a driving force distribution device provided in a path for transmitting a driving force from the driving source to the second driving wheel. 6. Force control device.

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