JP2017178202A - Control device for four-wheel drive vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a control device for a four-wheel drive vehicle, which need not excessively improve the dispersion accuracy of a system configuring component, which need not need a complex system dynamic analysis, and which does not bring the vehicle into an unstable behavior.SOLUTION: For a specified time(T*) from the instant of a zero rise of a command oil pressure (PCMD) or the stepwise change of the command oil pressure (PCMD), the limit of a restriction processing part 542c1 for a feedback control quantity (F/B control quantity) is released, and the feedback control quantity (F/B control quantity) is restricted by a restriction processing part for a time region excepting said specified time (T*). Moreover, the feedback control quantity (F/B control quantity) and the feedforward control quantity (F/F control quantity) are added to determine the driving current of a motor of an oil pump.SELECTED DRAWING: Figure 5

Description

  The present invention relates to a control device for a four-wheel drive vehicle that includes an actuator that regulates the hydraulic pressure of a hydraulically driven clutch as a driving force distribution device, and that performs control to determine a drive current of the actuator based on a command hydraulic pressure.

  Conventionally, as one of the electronically controlled four-wheel drive systems that switch between a two-wheel drive (2WD) state and a four-wheel drive (4WD) state, a front-rear torque is provided in the middle of a propeller shaft that connects a front differential mechanism and a rear differential mechanism. Hydraulic pressure that is provided with a distribution clutch, supplies hydraulic pressure (oil) that drives the clutch by an electric oil pump via a check valve, and maintains the engaged state of the clutch by sealing the supplied hydraulic pressure with a solenoid valve. An enclosed four-wheel drive system is known (see, for example, Patent Document 1).

  In addition, after a predetermined hydraulic pressure (clutch pressure) is sealed in the clutch, the clutch is engaged, that is, the clutch pressing force, that is, front and rear, by controlling the opening and closing of the solenoid valve provided between the clutch and the check valve. It is possible to change the distribution of torque transmitted to the wheels. 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 control, so that the motor frequency that is also a merit of the hydraulically enclosed four-wheel drive system without impairing 4WD performance. Suppression can be achieved.

  By the way, the command value of the front and rear wheel transmission torque necessary for the 4WD control is called command torque. When the actually generated transmission torque follows the command torque with high accuracy, the 4WD performance is improved. 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. In other words, the actual hydraulic pressure that is actually generated follows the command hydraulic pressure with high accuracy (hereinafter also referred to as “hydraulic accuracy”).

  In a hydraulic enclosure type four-wheel drive system, hydraulic feedback control (for example, PID control) using a hydraulic sensor is an essential technique when adjusting hydraulic pressure. However, when relying solely on hydraulic feedback control, the resistance to failure of the hydraulic sensor becomes a problem. In other words, when all of the hydraulic pressure adjustment control amount (for example, the motor drive current of the electric oil pump) is determined only by feedback control, the hydraulic control device takes in the actual hydraulic pressure that is different from the actual when the hydraulic sensor fails, A feedback control amount is calculated based on the wrong hydraulic pressure difference. As a result, an excessive driving current more than necessary flows to the motor, which causes a sudden increase in clutch pressure, and an excessive torque more than necessary is transmitted to the rear wheels, which may cause the vehicle to behave unsafely. is there. Therefore, a method is known in which most of the hydraulic pressure regulation control amount is determined by feedforward control that does not depend on a hydraulic sensor, and the feedback control amount is used within a range in which the vehicle does not behave unsafely.

JP 2013-067326 A

  In order to increase the hydraulic accuracy of the feedforward control amount, the dynamic characteristics (input / output characteristics) between the hydraulic pressure and the motor drive current in the hydraulic pressure regulation system (hydraulic supply system from the electric oil pump to the clutch) are highly accurate in advance. It is necessary to analyze with. In this analysis, a large number of sensors may be required to know the dynamic characteristics. Furthermore, it is necessary to improve the variation accuracy of system components.

  That is, when most of the hydraulic pressure regulation control amount is determined by feedforward control, there is a problem in that it is disadvantageous in terms of cost.

  Therefore, the present invention has been made in view of the above-mentioned problems of the prior art, and the object thereof is not to excessively improve the variation accuracy of system components, and a complicated system dynamic characteristic analysis is required. It is an object of the present invention to provide a control device for a four-wheel drive vehicle without causing the vehicle to fall into an unsafe behavior.

  In order to achieve the above object, a control device for a four-wheel drive vehicle according to the present invention applies drive force from a drive source (3) to first drive wheels (W1, W2) and second drive wheels (W3, W4). A driving force transmission path (20) for transmitting, a hydraulically driven clutch (10) as a driving force distribution device installed in the driving force transmission path (20), and an actuator (35 for adjusting the hydraulic pressure of the clutch (10)) , 37, 43) and control means (50) for performing control for determining the drive current of the actuator based on the command hydraulic pressure (PCMD), the control device for a four-wheel drive vehicle comprising: Based on the hydraulic pressure sensor (45) that measures the actual hydraulic pressure (PR) and the difference (ΔP) between the command hydraulic pressure (PCMD) and the actual hydraulic pressure (PR), the feedback control amount that determines the feedback control amount related to the actuator drive current is determined. A control unit (542a), a feedforward control unit (542b) that determines a feedforward control amount related to the drive current of the actuator based on input / output characteristics between the actual hydraulic pressure (PR) and the drive current of the actuator; An output unit (542c) that outputs a signal related to the drive current by adding the feedback control amount and the feedforward control amount, and a limit processing unit (542c1) that limits the feedback control amount within a predetermined range (LIML, LIMH). The control means (50) is configured to release the restriction on the feedback control amount for a specified time (T *) triggered by a predetermined change in the command hydraulic pressure (PCMD). And

  In the above configuration, the drive current of the actuators (35, 37, 43) is determined by the addition amount of the feedback control amount (F / B control amount) and the feedforward control amount (F / F control amount). . That is, the feedback control amount is a part of the element that determines the drive current of the actuator (35, 37, 43), and the feedforward control unit (542b) is the remaining that determines the drive current of the actuator (35, 37, 43). It becomes the element of. That is, the dependency (contribution) of each of the feedback control amount (F / B control amount) and the feedforward control amount (F / F control amount) as elements for determining the drive current of the actuator (35, 37, 43) is determined. Can be reduced. By reducing the dependency of the feedback control amount, the dependency of the hydraulic sensor (45) is reduced. As a result, resistance to the failure of the hydraulic sensor (45) is improved.

  On the other hand, by reducing the dependency of the feedforward control amount (F / F control amount), the analysis accuracy requirement level for system dynamic characteristics and the variation accuracy requirement level of system components are alleviated in the feedforward control unit (542b). Will come to be. Thereby, the cost increase of a four-wheel drive vehicle and a control apparatus is suppressed.

  Further, the control means of the control device for a four-wheel drive vehicle according to the present invention includes a limit processing unit (542c1) that limits the feedback control amount (F / B control amount) within a predetermined range. Therefore, the feedback control amount (F / B control amount) exceeding the predetermined range is cut by the restriction processing unit (542c1). Accordingly, when the hydraulic pressure sensor (45) is lost and the feedback control amount (F / B control amount) increases rapidly, the feedback control amount (F / B control amount) exceeding the predetermined range is limited by the limit processing unit. It is cut by (542c1). As a result, even if the hydraulic pressure sensor (45) fails and the feedback control amount (F / B control amount) is determined on the basis of the actual hydraulic pressure (PR) that is different from the actual value, excessive driving is performed. Current will not flow to the actuator.

  In the present invention, the control means is configured to release the restriction on the feedback control amount (F / B control amount) for a specified time (T *) triggered by a predetermined change in the command hydraulic pressure (PCMD). Yes. That is, for example, in a time region in which the command hydraulic pressure (PCMD) greatly changes, high hydraulic accuracy is required, and therefore the feedback control amount (F / B control amount) is not limited.

  By the way, a failure of the hydraulic sensor (45) may occur with a very low probability during the specified time (T *). However, after the stipulated time (T *) has elapsed, the feedback control amount (F / B control amount) is limited again by the limit processing unit (542c1). There are no unsafe behaviors.

  A second feature of the control device for a four-wheel drive vehicle according to the present invention is that the predetermined change is a change in the command hydraulic pressure (PCMD) from zero or a step-like change in the command hydraulic pressure. is there.

  In the above configuration, the feedback control amount (F / B control amount) is set in the time region within the specified time (T *) from when the command oil pressure (PCMD) rises to zero or when the command oil pressure (PCMD) changes stepwise. It is not restricted within a predetermined range. As a result, the actual oil pressure follows the command oil pressure (PCMD) with high accuracy in the time region within the specified time (T *).

  In the time domain excluding the specified time (T *), the feedback control amount (F / B control amount) is limited within a predetermined range by the limit processing unit (542c1). Therefore, an excessive drive current does not flow to the actuators (37, 43). Therefore, the vehicle does not fall into an unsafe behavior while the hydraulic control device is operating, including within the specified time (T *).

  Moreover, as one embodiment of the control device for a four-wheel drive vehicle according to the present invention, a piston chamber (15) that generates hydraulic pressure with respect to a piston (12) that presses and engages the clutch (10); An oil pump (35) for supplying hydraulic oil to the piston chamber (15) and a motor (37) for driving the oil pump (35) are provided. The actuator includes an oil pump (35) and a motor (37). It may be.

  Furthermore, a hydraulic oil sealing valve (39) for sealing hydraulic oil in an oil passage (49) leading from the oil pump (35) to the piston chamber (15), the hydraulic oil sealing valve (43) and the piston chamber (15 The hydraulic circuit (30) is configured with an on-off valve (43) for opening and closing the oil passage (49) between the actuator and the hydraulic oil sealing valve (43).

  According to the control device for a four-wheel drive vehicle of the present invention, the restriction on the feedback control amount (F / B control amount) is released only within a specified time from a predetermined change in the command oil pressure. As a result, it is possible to prevent the vehicle from falling into an unsafe behavior due to the failure of the hydraulic sensor while maintaining the minimum hydraulic accuracy with respect to the feedback control amount.

It is explanatory drawing which shows schematic structure of the four-wheel drive vehicle provided with the control apparatus which concerns on 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 block diagram which shows the structure of the motor output gate which concerns on this embodiment. It is explanatory drawing which shows the cancellation | release of restriction | limiting of the F / B control amount in case the change of command oil pressure is large. It is explanatory drawing which shows the restriction | limiting of F / B control amount in case the change of command oil_pressure | hydraulic is small.

  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.

  The output shaft (not shown) of the engine 3 is an automatic transmission 4, a front differential (hereinafter referred to as “front differential”) 5, and left and right front drive shafts 6, 6, which are first drive wheels. Are connected to the 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 and W4 which are 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 (actuator) 35 that sucks and feeds hydraulic oil stored in the oil tank 31 via a strainer 33, a motor (actuator) 37 that drives the oil pump 35, and an oil And an oil passage 40 communicating with the piston chamber 15 of the clutch 10 from the pump 35.

  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. Accordingly, the piston 12 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) (actuator) 43, and a hydraulic sensor 45 are installed in this order in the oil passage 40 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 of 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.

  Here, the operation of the hydraulic circuit 30 will be briefly described. First, the operation of the hydraulic circuit 30 when the vehicle 1 transitions from the 2WD state to the 4WD state will be described.

  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. 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. 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.

  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) in accordance with the command torque, and the control target value for the 2WD conversion block 532 to 2WD at the time of failure ( That is, the command hydraulic pressure PCMD) 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. Although details will be described later with reference to FIGS. 4 and 5, the PWM drive command signal is a feedback control amount (hereinafter referred to as “F / B control amount”) generated from the hydraulic pressure difference ΔP, and a command. It is generated by adding a feedforward control amount (hereinafter referred to as “F / F control amount”) generated from the hydraulic PCMD.

  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. As with the PWM drive command signal for the motor 37, the F / B control amount created from the hydraulic pressure difference ΔP and the F / F control amount created from the command hydraulic pressure PCMD are also determined for the ON / OFF instruction signal for the solenoid valve 43. Generated by adding.

  FIG. 4 is a block diagram showing a configuration of the motor PWM control block 542 according to the present embodiment. For convenience of explanation, the hydraulic pressure sensor 45, 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.

  Although the details will be described later with reference to FIGS. 5 and 6, the F / B control amount is usually controlled by the motor output gate 542 c and subjected to suppression processing (limit processing). Is added to Here, the “suppression process (limit process)” is a process of cutting an excess amount that exceeds the upper limit value LIMH or the lower limit value LIML for the F / B control amount.

  On the other hand, the F / B control amount is suppressed for a specified time T * from when the command hydraulic pressure PCMD rises to zero, or for a specified time T * from when the command hydraulic pressure PCMD changes significantly (for example, when the command hydraulic pressure PCMD changes stepwise). The processing is canceled (that is, the suppression processing is not performed) and added to the F / F control amount. Hereinafter, the motor output gate 542c will be described.

FIG. 5 is a block diagram showing the configuration of the motor output gate 542c according to this embodiment.
The motor output gate 542c includes a suppression processing block 542c1 that cuts the F / B control amount that exceeds the upper limit value LIMH or the lower limit value LIML, and a first determination block 542c2 that takes in the command hydraulic pressure PCMD and determines the zero rising state of the command hydraulic pressure PMCD. A second determination block 542c3 that takes in the command hydraulic pressure PCMD and determines a state in which the command hydraulic pressure PCMD has greatly changed (for example, a state in which the command hydraulic pressure PCMD has changed), and a selector that outputs a control signal to the selector 542c5 described later A control block 542c4, a selector 542c5 that selectively passes either an F / B control amount that has been subjected to suppression processing or an F / B control amount that has not been subjected to suppression processing, and an F output from the selector 542c5 Addition block 5 for adding the / B control amount and the F / F control amount And 2C6, the duty conversion block 542c7 for generating a PWM duty voltage (target drive current) from the addition of the F / B control amount and the F / F control amount, constituted by the NOR calculator NOR.

  In the first determination block 542c2, when a zero rising state of the command hydraulic pressure PCMD is detected, for example, “1” is output, and “0” is output otherwise.

  In the second determination block 542c3, for example, when a state in which the command hydraulic pressure PCMD is greatly changed (for example, a state in which the command hydraulic pressure PCMD changes) is detected, for example, “1” is output, and otherwise “0” is output. To do.

  Signals respectively output from the first determination block 542c2 and the second determination block 542c3 are input to a negative OR calculator NOR.

  In the NOR circuit NOR, the first determination block 542c2 outputs “1” (that is, the command hydraulic pressure PCMD rises to zero), or the second determination block 542c3 outputs “1”. “0” is output in any of the existing states (that is, the command hydraulic pressure PCMD has greatly changed), and “1” is output in other cases.

  When “0” is input from the NOR circuit NOR, the selector control block 542c4 operates the timer for a specified time T * and outputs “0” while the timer is operating. On the other hand, when “1” is input from the NOR circuit NOR, the selector control block 542c4 outputs “1”. Hereinafter, a signal output from the selector control block 542c4 will be referred to as a selector control signal.

  When the selector control signal is “1”, the selector 542c5 passes the F / B control amount subjected to the suppression process. That is, the upper path is selected. On the other hand, when the selector control signal is “0”, the F / B control amount not subjected to the suppression process is allowed to pass. That is, the lower path is selected.

  The addition block 542c6 adds the F / B control amount output from the selector 542c5 and the F / F control amount output from the F / F control block 542b. The added control amount is output to the duty conversion block 542c7 and converted into a corresponding PWM duty voltage (target drive current).

  FIGS. 6A and 6B are explanatory diagrams showing release of restriction of the F / B control amount when the change in the command hydraulic pressure PCMD is large. FIGS. 6A and 6B are time series data of the command hydraulic pressure PCMD and the selector control signal, respectively. FIG. 3C shows time-series data of the corresponding F / B control amount.

  The circles in FIG. 6 (a) indicate locations where the command hydraulic pressure PCMD has changed greatly. Part A shows a state in which the command hydraulic pressure PCMD rises from zero. Part B shows a state where the command hydraulic pressure PCMD rises stepwise. Part C shows a state where the command hydraulic pressure PCMD falls in a step shape. The “step shape” mentioned here means, for example, a discontinuous change of horizontal → vertical → horizontal.

  As shown in FIG. 6B, when the stepped falling state of the command hydraulic pressure PCMD is detected at time t3, the select control signal changes from “1” to “0”. At the same time, the select control signal is held at “0” for a specified time T * (t3 to t3 + T *).

  As shown in FIG. 6C, when the select control signal is “0”, the suppression process for the F / B control amount is released. That is, the lower path is selected in the selector 542c5 of the motor output gate 542c (FIG. 5). Therefore, even when the F / B control amount exceeds the lower limit value LIML, the F / B control amount is not cut and is added to the F / F control amount in the addition block 542c6 (FIG. 5). .

  At time t1 and time t2, a zero rising state and a stepped rising state of the command hydraulic pressure PCMD are detected. Similar to the time t3, the select control signal changes from “1” to “0”. At the same time, the select control signal is held at “0” for a specified time T * (t1 to t1 + T *, t2 to t2 + T *), and the suppression process for the F / B control amount is released. However, in this case, since the F / B control amount does not exceed the upper limit value LIMH and the lower limit value LIML, the effect of canceling the suppression process is not shown.

  FIG. 7 is an explanatory diagram showing the limitation of the F / B control amount when the change in the command hydraulic pressure PCMD is small. 7A shows the time series data of the command hydraulic pressure PCMD and the actual hydraulic pressure PR, and FIG. 7B shows the time series data of the corresponding F / B control amount.

  As shown in FIG. 7A, the command hydraulic pressure PCMD is substantially constant throughout (from time zero to t9). That is, the command hydraulic pressure PCMD does not show any state change of the zero rising state, the stepped rising state, or the stepped falling state shown in FIG. Therefore, the F / B control amount is subjected to suppression processing throughout.

  As shown in FIG. 7B, for example, at times t4 to t5, the F / B control amount exceeding the lower limit LIML is cut by the suppression processing block 542c1 (FIG. 5). Similarly, from time t6 to t7, the F / B control amount exceeding the lower limit value LIML is cut by the suppression processing block 542c1 (FIG. 5).

  Further, from time t7 to t8, the F / B control amount that exceeds the upper limit value LIMH is cut into the suppression processing block 542c1 (FIG. 5). In this case, the F / B control amount without the suppression process exceeds the direction in which the drive current of the motor 37 increases. Therefore, when the F / B control amount is not limited by the upper limit value LIMH, an excessive drive current flows to the motor 37, and more torque than necessary is distributed to the rear wheels. As a result, the vehicle 1 may behave unsafely.

  However, since the F / B control amount is limited by the upper limit value LIMH throughout, an excessive drive current does not flow to the motor 37 or the solenoid valve 43. As a result, excessive torque is not distributed to the rear wheels W3 and W4.

  On the contrary, from time t4 to t5, the F / B control amount without the suppression process exceeds the direction in which the drive current of the solenoid valve 43 decreases. Therefore, when the F / B control amount is not limited by the lower limit value LIML, the necessary drive current does not flow to the solenoid valve 43, and thus the necessary torque is not distributed to the rear wheels W3, W4. As a result, the vehicle 1 may behave unsafely.

  However, since the F / B control amount is limited by the lower limit value LIML throughout, it is possible to prevent the necessary drive current from flowing into the motor 37 or the solenoid valve 43. Note that the upper limit value LIMH and the lower limit value LIML are determined by looking at the degree of influence on torque change so as not to cause unsafe behavior as a vehicle.

  As described above, the ECU 50 (control means) according to the present invention is used when the command hydraulic pressure PCMD changes, specifically, when the command hydraulic pressure PCMD rises to zero, rises stepwise, or falls stepwise. The restriction on the F / B control amount is released for a specified time T * from the time of the time, and the F / B control amount is limited by the upper limit value LIMH and the lower limit value LIML in the time region excluding the specified time T *. Thereby, it is possible to prevent an excessive drive current or an excessive drive current from flowing to the motor 37 or the solenoid valve 43 while maintaining a minimum hydraulic accuracy with respect to the F / B control amount.

  The ECU 50 (control means) of the present invention determines the target drive current of the motor 37 or the solenoid valve 43 (actuator) based on the F / B control amount and the F / F control amount. Therefore, the F / B control amount or each dependency (contribution) of the F / F control amount as an element for determining the target drive current of the actuator can be reduced. By reducing the dependency of the F / B control amount, the dependency of the hydraulic sensor 45 is reduced. As a result, resistance to the failure of the hydraulic sensor 45 is improved.

  On the other hand, when the dependency (contribution) of the F / F control amount is reduced, the hydraulic accuracy with respect to the F / F control amount is relaxed. Thereby, in the F / F control block 542b, the analysis accuracy requirement level for the system dynamic characteristics and the variation accuracy requirement level of the system components are alleviated. Thereby, the cost increase of the four-wheel drive vehicle 1 is suppressed.

1 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 (hydraulic drive type 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) (actuator)
37 Motor (pump motor) (actuator)
39 Check valve (hydraulic oil sealing valve)
41 Relief valve 43 Solenoid valve (open / close valve) (actuator)
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)
PCMD Command hydraulic pressure PR Actual hydraulic pressure LIMH Upper limit LIML Lower limit

Claims (4)

A driving force transmission path for transmitting a driving force from a driving source to the first driving wheel and the second driving wheel;
A hydraulically driven clutch as a driving force distribution device installed in the driving force transmission path;
An actuator for regulating the hydraulic pressure of the clutch;
Control means for performing control to determine the drive current of the actuator based on command oil pressure, and a control device for a four-wheel drive vehicle,
A hydraulic sensor for measuring the actual hydraulic pressure of the clutch;
A feedback control unit that determines a feedback control amount related to a drive current of the actuator based on a difference between the command hydraulic pressure and the actual hydraulic pressure;
A feedforward control unit that determines a feedforward control amount related to the drive current of the actuator based on input / output characteristics between the actual hydraulic pressure and the drive current of the actuator;
An output unit for adding the feedback control amount and the feedforward control amount to output a signal related to the drive current;
A limit processing unit that limits the feedback control amount within a predetermined range,
The control device for a four-wheel drive vehicle, wherein the control means is configured to release the restriction on the feedback control amount for a specified time triggered by a predetermined change in the command hydraulic pressure.   The control device for a four-wheel drive vehicle according to claim 1, wherein the predetermined change is a rise change from zero of the command oil pressure or a step-like change of the command oil pressure. 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,
The control device for a four-wheel drive vehicle according to claim 1, wherein the actuator is the oil pump and the motor. A hydraulic oil sealing valve for sealing hydraulic oil into an oil passage leading from the oil pump to the piston chamber;
An open / close valve for opening and closing the oil passage between the hydraulic oil sealing valve and the piston chamber,
The control device for a four-wheel drive vehicle according to claim 3, wherein the actuator is the hydraulic oil sealing valve.

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