JPS62251238A - Control method for four-wheel driven vehicle - Google Patents

Abstract

PURPOSE:To perform each control in a stable condition, by starting one control of either a directly coupled clutch or a driving power distribution control mechanism thereafter inhibiting the execution of the other control before a preset condition is satisfied. CONSTITUTION:A four-wheel driven vehicle is equipped with an oil hydraulic directly coupled clutch control device 6, which places a driving side member of a torque converter 5 and its driven side member in a directly coupled condition, and a driving power distribution control mechanism 13, which distributively controls driving power for front and rear wheels, and in this vehicle, the directly coupled clutch control device 6 and the driving power distribution control mechanism 13 or the like are controlled by a control unit 1. Here in case of starting one control of either the directly coupled clutch control device 6 or the driving power distribution control mechanism 13, execution of the other control is inhibited thereafter till a preset condition is satisfied. This condition is set as a condition including either a lapse of the preset time or the end of the one control.

Description

[Detailed Description of the Invention] Industrial Application Field This invention relates to a method for controlling a four-wheel drive vehicle on an as-needed (part-time) or a permanent basis (full-time), and particularly in controlling the distribution of driving force between the front and rear wheels and the fluid coupling. The present invention relates to a control method for a four-wheel drive vehicle that performs direct coupling clutch switching control.

Conventional technology Since four-wheel drive has advantages such as excellent running stability, it has recently been adopted in regular passenger cars and small passenger cars. The four-wheel drive format includes a part-time four-wheel drive that can arbitrarily cut off the transmission of drive power to the front or rear wheels, and a differential M system that constantly distributes drive power to both wheels after a turn. Can it be divided into full-time four-wheel drive? Conventionally, these types of four-wheel drive devices and automatic transmissions and automatic transmissions have been divided into high and low two types.
This is done by combining the automatic transmission with an auxiliary transmission, and also directly connects the driving side member and driven side member to the fluid coupling that connects the engine and automatic transmission to improve fuel efficiency. It is common practice to incorporate a direct coupling clutch that connects the vehicle.

An example of this is proposed in Japanese Patent Application No. 59-275483. This system connects the automatic transmission to the engine via a torque converter with a built-in direct-coupling clutch, and connects the automatic transmission to a four-wheel drive transfer system that has an auxiliary transmission that switches between high speed (high) and deceleration (low). This is a configuration provided on the connection side. Here, the direct coupling clutch connects and disconnects the driving side member (for example, the front cover integrated with the pump impeller) and the driven side member (for example, the hub integrated with the turbine runner) in the Luk converter, and is engaged by hydraulic pressure. Engagement/release control is performed and engagement]1
4, the drive horn is transmitted to the driven member without going through the torque converter. The four-wheel drive transfer is configured to transmit the rotation of the rear export horn shaft to the front export shaft via the clutch J3 and the power transmission mechanism. It becomes a wheel drive, and when it is released it becomes a two-wheel drive, but this clutch is a wet type multi-disc clutch, and when it is in an engaged state that allows slipping, such as a so-called half-clutch, the driving force is transferred to the rear export power shaft and the front export horn shaft. The distribution ratio can be adjusted accordingly, and the clutch thus becomes a driving force distribution control mechanism.

Conventionally, a four-wheel drive transfer mainly composed of a differential gear V is disclosed in US Pat. No. 4, for example.
538.7oo@It is described in the specifications, and in the four-wheel drive transfer, the driving force is always transmitted to all four wheels, but for example, when the load on the front wheels and the rear wheels is extremely different, Since there is a risk that one wheel with a small load will idle and the other wheel will not rotate, resulting in essentially two-wheel drive, a clutch is provided to fix the differential gear so that it does not function. If this clutch is fully engaged, the driving force can be equally transmitted to the front wheels and rear wheels, and if the clutch is slightly collapsed, the driving force can be distributed between the front wheels and the rear wheels. The ratio can be set appropriately, and the clutch therefore also serves as a drive force distribution control mechanism.

Problems to be Solved by the Invention The direct coupling clutch changes the state of transmission of driving force from the engine to the transmission, whereas the drive horn distribution control mechanism distributes the panned driving force to the four wheels. [1][1]
). If this is not the case, the load will fluctuate for the direct clutch, and the driving force distribution control mechanism will fluctuate dramatically, making it difficult to perform smooth and accurate control such as preventing engagement shock. Become. This can be explained in terms of hydraulic pressure as follows. In other words, among the above-mentioned configurations, the direct coupling clutch is generally engaged or released by operating a valve by operating a switch to change the hydraulic pressure supply path, but in the engaged state, the drive side member and the driven side of the torque converter are connected to each other. Since the members are mechanically connected and there is no buffering effect due to fluid, the hydraulic pressure is adjusted or an accumulator is provided to eliminate shock during engagement. On the other hand, the clutch serving as the drive horn distribution control mechanism described above generally engages or disengages a valve by switching a valve by operating a lever or a switch depending on the road surface condition.

However, in the past, since the control of the direct coupling clutch and the control of the driving force distribution control mechanism were performed independently of each other, switching control of both may occur at the same time. In such a case, the hydraulic pressure that has been regulated to a constant pressure at a regulator valve, etc., decreases due to a sudden increase in the point where it should be supplied, and as a result, the clutch engagement timing and engagement force may be affected. If the control does not go as expected and the control is disturbed, especially when performing slip control of the direct coupling clutch or the tardge of the drive force distribution control mechanism, changes in the rotation speed of the drive saw 9 will affect the control of the other side, resulting in smooth control. A problem arises in which control becomes difficult.

This invention was made in view of the above circumstances, and is a four-wheel drive vehicle that can smoothly control the direct coupling clutch and the mechanism that controls the distribution of driving force to the front wheels and the rear wheels. The purpose is to provide a control method.

Means for Solving the Problems In order to achieve the above object, the present invention performs control of the direct coupling clutch and the driving force distribution control mechanism in relation to each other, and after the control of either one starts, the control is performed in advance. This is a control method for a four-wheel drive vehicle that prohibits control of the other until a set condition is met.

The start of control here refers to the output of a control start signal, the start of changes in the hydraulic pressure in the hydraulic pressure supply path to the controlled object, etc.
This includes the start of a change in the rotational speed of a rotating member related to the controlled object, the torque, etc., and is not limited to the start of a change in the behavior of the controlled object. Further, the condition may be the elapse of a set time or the end of a previously started control, and the end of the control is determined by either the comparative judgment result of the rotational speed of the rotating member or the comparative judgment result of the hydraulic pressure. It can be decided depending on.

Accordingly, in the method of the present invention, after either the control of the direct coupling clutch or the control of the driving force distribution control mechanism is started, the control of the other is prohibited and reserved for a predetermined period, and then the control of the other is stopped. Since this is carried out, the new operating state can be stabilized, such as recovering the oil pressure, during the reservation period. As a result, in the present invention, all controls are performed under assumed hydraulic pressure or operating conditions, making stable control possible.

Example Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a flowchart for explaining an example of the method of the present invention. This method is performed in association with control, and in order to perform this method by electrical control, it is preferable to use the system schematically shown in FIG. In FIG. 2, reference numeral 1 is a control unit mainly composed of a microcomputer, and to this control unit 1, various signals are inputted from the engine 2 through a position sensor 3 and an engine rotation sensor 4. Regarding the torque converter 5, a direct coupling clutch control device 6 is operated by an output signal from the control unit 1, and a signal from a direct coupling clutch operation sensor 7 is inputted to the control units 1 to 1 in order to obtain the operating status of the direct coupling clutch control device 6. Here, the direct-coupling clutch control device 6 can be, for example, a solenoid valve and an L1 pull-up relay valve controlled by the solenoid valve, and the direct-coupling clutch operating hinge 7 can be a pressure switch interposed in the oil path leading to the direct-coupling clutch. . Furthermore, automatic transmission 8
In this case, the control unit control device 9 is operated, and signals from the automatic transmission rotation sensor 10 and the automatic transmission operation sensor 11 are input to the control unit 1 in order to obtain the respective operation status. Here, as the automatic transmission 8 and its control device 9, the device shown in the above-mentioned Japanese Patent Application No. 59-275483@ can be adopted. Various valves are switched depending on the engine speed and output shaft rotation speed, and the speed is automatically changed.

Therefore, as the automatic transmission operation sensor 11, a pressure switch that detects the oil pressure for a brake or a clutch for changing gears can be used. On the other hand, regarding the four-wheel drive transfer 12, the driving force distribution controller #l1 is activated by the output signal from the control unit 1.
13, and in order to obtain the operating state thereof, each signal from the driving force distribution control (t4 operation sensor IJ-14, rear wheel speed sensor 15, and front wheel speed sensor 16) is input. Here, The above mentioned patent application 1975-275
The device of No. 483 switches between two-wheel drive and four-wheel drive by engaging and disengaging the clutch using hydraulic pressure, and by adjusting the engagement force of the clutch, λt1 is applied to the rear wheels and front wheels. Since the distribution rate of the driving force can be changed, a pressure switch that detects the oil pressure for the clutch can be used as the driving force distribution control mechanism operation sensor 14. The controller 1 to roll unit 1 further includes an automatic transmission shift 1 position sensor 17 and a driving force distribution control mechanism position sensor 18.
, left wheel rotation sensor 9-19, right wheel rotation sensor 20,
Signals from a steering angle sensor 21, a road surface sensor 22, a gradient sensor 23, and a brake operation sensor 24 are input.

In the above system, for example, when switching the direct coupling clutch and switching the driving force distribution control mechanism 13, the position sensor 1 corresponding to each
A signal is input to the control unit 1 from 7.18. In the control unit 1, as shown in FIG.
YES], switching of the driving force distribution control mechanism 13 II
! I control is prohibited (step 101). This is done by outputting a signal from the control unit 1 or by prohibiting the output of the signal. Specifically, the driving force distribution control mechanism 13 controls two-wheel drive by engaging and releasing the clutch or adjusting the engagement force. If the system switches to four-wheel drive or controls the distribution rate of driving force, the valve is controlled to maintain the current state of the clutch.

That is, to explain the case where the driving force distribution control mechanism has the υ configuration shown in FIG. 3 and prohibits switching to four-wheel drive, the manual valve 30 in FIG. The port 31, which is connected to the hydraulic pressure source P1 that generates line hydraulic pressure, is connected to the movement of the spool 32. This is a mechanism that selectively communicates with the four-wheel drive port 33 and the sub-transmission port 34, and the four-wheel drive port 33 communicates with the timing valve 35. It has a configuration in which a spring 37 is disposed on one end and an oil chamber 38 is provided on the other end, and the outlet port 39 connects a flow control valve 40 with a check valve to the clutch C-4 for switching between two-wheel drive and four-wheel drive. connected via.

By pushing the spool 36 with the spring 37, the timing valve 35 is operated at the inlet ports 1 to 41.
is closed, the outlet port 39 communicates with the drain port 42, and the hydraulic pressure for the clutch C-4 is discharged, and by applying line hydraulic pressure to the oil chamber 38,
The spool 36 compresses the spring 37 and moves to one end side, and as a result, the inlet reflex 1 to port 41 and the rear 1 to let port 39 communicate with each other to apply hydraulic pressure to the ramp C-4. The oil pressure 38 in the timing valve 35 is communicated with the oil pressure source PI via an oil passage 43, and a solenoid valve S5 is interposed in the oil passage 43 immediately before the oil chamber 38. This electromagnetic valve S5 listens to the port by energizing and energizing the coil, and discharges pressure from the oil passage 43, that is, from the oil chamber 38, and conversely, by demagnetizing it, the port is closed and the pressure is discharged from the oil passage 43 and the oil chamber 38. The control unit 1 applies line hydraulic pressure to the control unit 1.
It is connected to the. Note that a pressure switch PS-, which is a driving force distribution control mechanism operation sensor 14, is provided between the clutch C-4 and the flow control valve with check valve/10.

Therefore, in the configuration shown in FIG.
If 0 is set to H4 or L4 and 1 is set, the port 31 communicates with the four-wheel drive port 33 and line oil pressure is applied to the inlet port 41 of the timing valve 35, but the solenoid valve S5 is energized to turn it on. If the condition is maintained, pressure is exhausted from the oil chamber 38 in the timing valve 35 and the spool 3
6 goes down to the bottom of Figure 3, so inlet port 4
1 is closed, and therefore no line oil pressure is supplied to the clutch C-4, and it is possible to prohibit the clutch C-4 from engaging and causing the four wheels to move in one direction.

As described above, with the switching control of the driving force distribution control mechanism 13 prohibited, the switching LD control of the direct coupling clutch is performed n1 (step 102). This can be done, for example, by changing the oil pressure supply route to the direct coupling clutch by switching off the lock-up valve using a solenoid valve in the direct coupling clutch control device 6. The start of switching control of the direct coupling clutch is determined by the output of a signal from the control unit 1 to the direct coupling clutch control device 6, the output signal from the direct coupling clutch actuation sensor 7, etc., and in the next step 103, the switching control of the direct coupling clutch is After executing the switching control, it is determined whether preset conditions are satisfied.

The judgment process in step 103 is essentially to suspend the next control until the oil pressure fluctuations caused by the preceding direct coupling clutch switching control are resolved and the oil pressure is stabilized. This may be the end of switching control of the direct coupling clutch or the elapse of a preset time. Here, the end of the switching control is determined based on the result of comparing and judging the oil pressure based on the signal picked up by the direct coupling clutch actuation sensor 7 and the result of comparing and judging the rotational speed based on the signal picked up by the automatic transmission actuation sensor 11. be able to. Further, the set time may be determined by measuring the time required for the oil pressure to stabilize. If the determination result in step 103 is "no", the process returns to step 101 and the prohibition of switching control of the driving force distribution control mechanism 13 is maintained.

If the determination result in step 103 is "yes" or if the determination result in step 101 is "no", the control based on the input signal is performed by the driving force distribution control mechanism 1.
3 is switched (step 104). If the result of this judgment process is "no", the process returns to the first step, and if the result is "yes", switching control of the direct coupling clutch is prohibited (step 105). This prohibition of switching control of the direct coupling clutch can be achieved, for example, by maintaining the current state of energization and demagnetization of the electromagnetic valve in the direct coupling clutch control device 6. With this type of control prohibited, switching control of the driving force distribution control mechanism 13 is performed (step 106).

In this switching control, when switching from two-wheel drive to four-wheel drive in the example shown in FIG. By supplying line hydraulic pressure to the oil chamber 38 and moving the spool 36 upward in FIG. 3, the inlet port 41 and the outlet port 1/39 are communicated with each other, and the line hydraulic pressure engages the clutch C-4. This can be done by letting In this case, since the hydraulic pressure has been restored, such as by completing the switching control of the preceding direct coupling clutch, the switching control in the driving force distribution control mechanism 13 is performed as expected.

After starting the switching control in step 106, it is determined whether preset conditions are satisfied (step 107). The conditions here are step 103 from the previous 3g.
In the same way as the conditions in , the end of the switching control or the elapse of the R-shift period may be used. Comparative judgment results of the rotation speed based on the signal and the above-mentioned drive) J
It can be determined based on the comparison judgment result of the oil pressure based on the output signal from the distribution control mechanism operation sensor 14. If the result of the determination process in step 107 is "no", the process returns to step 105 and the prohibition of new speed change control of the direct coupling clutch is maintained. Also, the judgment result is “yes”
If so, return to the first step.

FIG. 4 is a time chart i showing the output timing of each switching signal under the above control and the operation timing of the direct coupling clutch and the driving force distribution control mechanism 13. When an operation to switch to four-wheel drive is performed, the direct coupling clutch control device 6 starts control to engage the direct coupling clutch in response to the direct coupling signal, but there is a prohibition period T from time 10 until the above conditions are satisfied.
Even if there is a switching signal from two-wheel drive to four-wheel drive (2 to 4) at time t1 within 1, the J distribution control 13 is maintained in its previous state, and at time t2 when the prohibition period T1 has elapsed. At this point, the switching operation of the driving force distribution control mechanism 13 is started. Thereafter, even if there is a switch signal for releasing the direct coupling of the direct coupling clutch at a predetermined time t3 within the prohibition period T2 until a preset condition is met, the direct coupling clutch is maintained in its previous state, and the prohibition period T2 has elapsed. At time t4, the direct coupling clutch starts to be disengaged. Thereafter, each prohibition period T1,
At T2, switching control of the direct coupling clutch and switching control of two-wheel drive and four-wheel drive do not occur at the same time, and control of either one is blocked. As a result, both the switching control of the direct coupling clutch and the switching control of the driving force distribution control mechanism are performed under the specified oil pressure without causing a drop in the oil pressure.

83 In the above explanation, it is determined first whether or not to switch the direct coupling clutch, and whether or not to switch the drive horn distribution control mechanism is determined later, but these priorities are not particularly limited. Rather, no matter which one you judge first,
stomach. Alternatively, the process from step 100 to step 103 and the process from step 104 to step 107 may be performed independently, in which case the routine based on the first input signal will precede. In addition to the configuration for switching between two-wheel drive and four-wheel drive, the driving force distribution control mechanism targeted by this invention can also be used to fix and release a differential mechanism. The method of the present invention includes a structure in which a single clutch is used for transmitting driving force to four wheels and for differential operation. It can also be applied to the case where the distribution ratio of the driving force between the wheels and the rear wheels is adjusted in the range from 1:1 to 〇. In general, the present invention can also be applied to the case of performing slip control of a direct coupling clutch. Generally speaking, the driving force distribution control mechanism to which this invention is directed is not limited to a hydraulic type, but may be configured to operate mechanically.

As described in detail, according to the method of the present invention, the distribution control of the drive horns to the front wheels and the rear wheels and the switching control of the direct coupling clutch are executed with a predetermined time lag. Control is carried out in a stable state beyond a transient state, and there is no temporary significant drop in the oil pressure that performs these controls.
Therefore, each control can be carried out stably as expected, and as a result, in addition to obtaining good shifting characteristics, it is also possible to finely adjust the distribution ratio of driving force between the front wheels and the rear wheels. 1. Also, the inherent merits of a four-wheel drive vehicle 1~
It can be done without taking advantage of it.

[Brief explanation of drawings]

FIG. 1 is a flowchart showing an embodiment of the method of the present invention.
1 to 2 are schematic illustrations of a system for carrying out the control method, FIG. 3 is a schematic illustration showing an example of a driving force distribution mechanism, and FIG. 4 is a time chart according to the method shown in FIG. 1. . 1... Control unit, 5... Torque converter, 6... Control device for direct coupling clutch, 13.
...Driving force distribution control mechanism, C-4...Clutch,
S5... Solenoid valve.

Claims (4)

[Claims] (1) A hydraulic direct-coupling clutch that directly connects the driving side member and the driven side member in the fluid coupling, and a driving force distribution control mechanism that controls the distribution of driving force between the front wheels and the rear wheels. In a wheel drive vehicle, after starting control of either the direct coupling clutch or the driving force distribution control mechanism, control of the other is prohibited until a preset condition is satisfied. How to control a four-wheel drive vehicle. (2) The method for controlling a four-wheel drive vehicle according to claim 1, wherein the condition includes either the elapse of a set time or the termination of the one control. (3) The end of the control is determined based on a comparison result of the rotational speed of a member connected to the fluid coupling or a member connected to the driving force distribution control mechanism. A method for controlling a four-wheel drive vehicle as described in Section 3. (4) A patent characterized in that the driving force distribution control mechanism is configured to operate by hydraulic pressure, and the termination of the control is determined by a comparison judgment result of the hydraulic pressure in the fluid coupling or the driving force distribution control mechanism. Claim 2
A method for controlling a four-wheel drive vehicle as described in Section 3.