JPH0712793B2 - Vehicle power transmission device - Google Patents

Description

TECHNICAL FIELD The present invention relates to a power transmission device for a vehicle, and more specifically,
The present invention relates to a power transmission device capable of suitably controlling the operation of a torque distribution unit capable of controlling a torque distribution amount between right and left or front and rear wheels.

(Prior Art) In a vehicle, a differential device is inserted in an axle shaft that transmits a driving force from a power plant to both left and right driving wheels, and this device allows rotation between the two wheels during turning. Both wheels are rotated differentially to absorb the difference. However, when such a differential device is inserted, when one wheel idles, torque is lost from the wheel on the idle side, and the amount of torque transmission to the other side decreases,
This causes a harmful effect such as an automobile being stopped. Therefore, in the prior art, a differential locking device is arranged, and when slip or idling occurs on one of the wheels, or when there is a possibility of slippage, the differential of the differential device is prohibited and the differential on the other side is prohibited. In order to transmit the torque only by the wheels and maintain the running condition, both wheels are directly connected. Japanese Unexamined Patent Publication (Kokai) No. 60-135325 discloses an example of this type of device, in which the differential locking is performed only when the steering angle is small and the inclination angle of the vehicle body in the vehicle width direction is large. The differential is locked by operating the device to prohibit differential rotation so that torque is equally distributed to both wheels.

(Problems to be Solved by the Invention) Here, it is conceivable that such a torque distribution unit (the differential device in the above example) can be controlled to a locked state by a manual operation. However, in this case, since the driver can freely perform the lock control, the following problems occur.

For example, when the torque distribution means is locked during sudden acceleration and the left and right wheels or the front and rear wheels are directly connected,
Excessive stress may act on the torque distribution means, which may cause a large shock, and also reduce the durability of the torque distribution means. Further, if the vehicle is locked during turning, the turning radius will suddenly change, which will cause a braking phenomenon. Furthermore, when the torque distribution means is arranged between the front and rear wheels, if the torque distribution means is locked during braking to shift from the two-wheel drive state to the four-wheel drive state, the distribution amount of the braking force to each wheel suddenly changes. However, braking performance or running stability may be impaired.

An object of the present invention is to provide a power transmission device for a vehicle that solves such problems.

(Means for Solving the Problems) In order to achieve the above object, in the power transmission device of the present invention, even when there is a manual input for locking the torque distribution means, under a certain traveling state, The torque distribution means is not locked.

That is, the power transmission device of the present invention inputs the torque distribution means A for distributing the torque between the left and right wheels or the front and rear wheels as shown in FIG. 1, and a command for inhibiting the operation of the torque distribution means. Input means B for operating, and a locking means C that operates when the command is input and that directly connects both wheels to which torque is distributed by the torque distribution means,
When the traveling state detecting means D for detecting the traveling state of the vehicle and the detected traveling state coincide with a predetermined state,
A prohibiting means E for prohibiting the operation of the locking means even when the command is input is provided.

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

First Embodiment FIGS. 2 to 5 show an embodiment of the present invention in which a torque distribution means is inserted between the front and rear wheels of a four-wheel drive vehicle. In FIG. 2, reference numeral 10 indicates a power plant, and the power plant 10 is composed of an engine, a transmission and the like. This power plant
A front side propeller shaft 14 is connected to an output shaft 12 of the gear 10 via a gear train 13, and a rear side propeller shaft 16 is connected to the output shaft 12 via a hydraulic variable clutch 15 which is torque distribution means. The front side propeller shaft 14 is connected to the front wheels 8 via a final gear unit 17. In addition, the rear side propeller shaft 16
It is connected to the rear wheel 20 via the final gear unit 19. In this way, from the power plant 10, the output shaft 12,
A torque transmission path is formed to reach the front wheels 18 via the gear train 13, the propeller shaft 14 and the final gear unit 17, and a torque transmission path is formed to reach the rear wheels via the output shaft 12, the clutch 15 and the final gear unit 19. It is formed. Then, the pressure of the hydraulic oil applied to the clutch 15 is changed to change the transmission torque amount of the clutch 15 to adjust the torque distribution ratio of the front and rear wheels.

Next, the hydraulic control system of the clutch 15 will be described with reference to FIG. As shown in the figure, the hydraulic oil in the oil tank 21 is sucked up by the pump 22, discharged at a predetermined pressure, and supplied to the hydraulic oil chamber 15a of the clutch 15 via the hydraulic pressure control valve 23. The hydraulic control valve 23 has a control unit 24
The hydraulic oil chamber 15a of the clutch 15 is controlled by
The pressure P of the hydraulic oil to is adjusted. That is, the fastening force between the friction plates 15b of the clutch 5 is controlled.

The control unit 24 is composed of a microcomputer, the input side of which is a vehicle speed sensor 25, a steering angle sensor 26,
Various sensors such as a speed difference sensor 27, a kick down switch 28, and a braking sensor 29 for detecting a running state are connected. Vehicle speed sensor 25 outputs a vehicle speed signal S _v corresponding to the vehicle speed by detecting the vehicle speed. The steering angle sensor 26 is
A steering angle is detected and a steering angle signal Sθ corresponding to the detected value is output. Speed difference sensor 27, the rotational speed difference between the torque input side and the output side, i.e. to detect the rotational speed difference delta _n between the front end and rear propeller shafts 14 and 16, and outputs a speed difference signal SΔ _n. Kickdown switch 28
Outputs a kickdown signal S _kd when the accelerator (not shown) is suddenly deeply depressed. Further, the braking sensor 29 outputs a braking signal S _br when the brake pedal (not shown) is stepped on and is in a braking state.

The control unit 24 uses the signal Esuderuta _n, calculates the control current i from a control map stored in advance, and supplies the calculated current i to the hydraulic control valve 23. In this example, the control current i
And the control oil pressure P by the control valve 23 are in a proportional relationship, and the control oil pressure P and the transmission torque amount T _r by the clutch 15 are also in a proportional relationship. In the present embodiment, the change of the control current i, for example, the fourth, as shown in FIG, so that the transmission torque characteristics for rotation speed difference delta _n is obtained.

Here, a selection switch 30 is further connected to the input side of the control unit 24. The selection switch 30 is arranged on the operation panel of the driver's seat and is used to select the control mode of the hydraulic clutch 15. When the selection button 30a is pressed, the signal I _SW (= 1) instructing the release mode is input to the control unit 24. In the control unit 24, the current i is set to zero and the valve 23 is closed. As a result, the hydraulic pressure P becomes zero, the hydraulic clutch 15 becomes disengaged, and the amount of transmission torque _Tr toward the rear wheel side becomes zero. That is, it becomes a complete front wheel drive state. On the other hand, when the selection button 30b is pressed, the signal I _SW (= 2) instructing the automatic control mode is input to the control unit 24. In this case, the control of the current i, that is, the control of the hydraulic pressure P is performed so that the transmission torque amount T _r is determined according to the rotation speed difference Δ _n as shown in FIG. On the other hand, when the selection button 30c is pressed, the signal I _SW (= 3) instructing the lock mode is input to the control unit 24. In this case, as a general rule, the hydraulic clutch 15 maximum hydraulic pressure acts and the front and rear wheels are directly connected,
Under certain driving conditions, such lock control is not performed.

FIG. 5 is a flowchart showing the mode switching control described above. When any of the buttons 30a, 30b, 30c in the selection switch 30 is pressed, the process proceeds to step ST1 and it is determined which button is pressed. When the button is the button 30a for instructing the disengagement mode, the process proceeds to step ST7 to immediately control the hydraulic clutch in the disengagement mode. When the pressed button is the button 30b for instructing the automatic control mode, the process proceeds to step ST8 and immediately controls the hydraulic clutch in the automatic control mode. That is, as shown in FIG. 4, the difference in rotational speed between the front and rear wheels Δ _n
In order to control the transmission torque amount _Tr according to
Therefore, the hydraulic pressure P is controlled.

However, the pressed button is the button 30 that commands the lock mode.
When it is c, the determinations shown in steps ST2 to ST5 are sequentially performed, and when the traveling state is not the predetermined specific state, the process proceeds to step ST6 to control the hydraulic clutch in the lock mode. However, when in a specific state, the lock control is not performed and the mode previously selected is retained. One of the above specific states is when the kickdown signal S _kd is input when the vehicle speed v is lower than the predetermined vehicle speed v _s (steps ST2, ST3). In other words, it is in a state of sudden acceleration. Another one of the specific states is when the steering angle θ is equal to or _larger than a predetermined steering angle θ _s (step ST4). This is a state at the time of turning with a predetermined turning radius or less. Furthermore, another one of the specific states is when the braking signal S _br is input (step ST5). This is the state during braking. When the traveling state is any one of these states, the shift to the lock mode is not performed. If neither of these states exists, the maximum current is applied to the valve 23 so that the maximum hydraulic pressure is applied to the hydraulic clutch 15, as described above. As a result, the hydraulic clutch 15 is locked and the front and rear wheels are directly connected. In this direct connection state, the torque distribution between the front and rear wheels becomes substantially equal.

Second Embodiment FIGS. 6 and 7 are views showing another embodiment of the present invention, in which a torque distribution means is arranged between the rear wheels of a rear-wheel drive vehicle.

In FIG. 6, reference numeral 41 indicates a power plant, and the power plant 41 is composed of an engine, a transmission and the like. A propeller shaft 47 is connected to an output shaft 43 of the power plant 41 via a universal joint 45. The shaft 47 is connected to an input shaft 511 of a differential device 51 via a universal joint 49. Left and right output shafts 513R, 513L of this differential device 51
Are connected to left and right rear wheels 55R and 55L via left and right axle shafts 53R and 53L, respectively.

Next, with reference to FIG. 7, the structure of the differential device 51 and its hydraulic control system will be described. As shown in the figure,
The differential device 51 includes a drive pinion 515 fixed to the base end of the input shaft 511, and a ring gear 5 rotatably arranged around the outer periphery of the left output shaft 513L and in mesh with the drive pinion 515.
17, a differential case 519 that rotates with this ring gear, and the left and right output shafts 513 in this case.
A pair of pinion shafts 5 arranged in the diameter direction of R and L
21 and pinion 523 fixed to the tip of these shafts
And the pinion 52 fixed to the base ends of the left and right output shafts 513R and L.
It has a side gear 525 meshed with 3. This structure is similar to a known differential device. However, the device 51 of this example
Is equipped with a lock mechanism that prohibits differential control and directly connects the left and right output shafts 513R and 513L. That is, a cylindrical clutch cylinder 527 is coaxially formed on the right end surface of the case 519 by extending the outer peripheral wall of the case, and a clutch hub 529 is coaxially arranged inside the cylindrical clutch cylinder 527. . The clutch hub 529 is attached to the output shaft 513R so as to be slidable only in the axial direction. A plurality of annular friction plates 527a and 529a are attached to the clutch cylinder 527 and the clutch hub 529, and the friction plates 527a and 529a are arranged alternately. These friction plates 527a and 529a are clutch cylinders.
The hydraulic chamber 531 formed between the 527 and the clutch hub 529 is fastened by applying a predetermined hydraulic pressure P1. By this fastening, the right output shaft 513R and the differential case 51
9 and are connected. Therefore, the differential control of the differential device 51 is prohibited, and the left and right wheels 55R and 55L are directly connected.

Next, a hydraulic control system for controlling the supply of hydraulic oil to the hydraulic chamber 231 will be described. As shown in the figure, the hydraulic oil in the oil tank 57 is sucked up by the pump 59, discharged at a predetermined pressure, and supplied to the hydraulic chamber 531 via the opening / closing valve 61. The opening / closing valve 61 is controlled to be opened / closed by the control unit 63, which controls whether or not hydraulic oil is supplied to the hydraulic chamber 531.

On the input side of the control unit 63, a vehicle speed sensor 65, a steering angle sensor 67, a kick down switch 69, a braking sensor 71
A running state detection sensor including the above is connected. Here, the vehicle speed sensor 65 outputs a vehicle speed signal S _v corresponding to the vehicle speed by detecting the vehicle speed. The steering angle sensor 67 detects the steering angle and outputs a steering angle signal Sθ corresponding to the detected value. The kick down switch 69 outputs a kick down signal S _kd when the accelerator is suddenly deeply depressed. Further, the sensor 71 outputs the braking signal S _br when the brake pedal is depressed and the braking state is set.

Here, a changeover switch 73 is further connected to the input side of the control unit 63. The changeover switch 73 is for inputting a command as to whether or not the differential device 51 should be locked, and when the switch 73 is turned on, the lock command signal 73s is input. Upon receipt of this signal, the control unit 63 in principle supplies a current i1 to the valve 61. As a result, the on-off valve 61 is opened and the hydraulic oil P1 acts in the hydraulic chamber 531, whereby the clutch hub 529 moves to the right. As a result, the friction plates 527a and 529a are fastened, and the left and right output shafts 513R and 513L are directly connected. Therefore, both left and right wheels 55
Equal torque distribution is applied to R and 55L.

However, during rapid acceleration, i.e. the vehicle speed v is less than or equal a predetermined value v _s, when the kick-down signal S _kd is input, when turning the turning radius is small i.e. the steering angle theta than a predetermined value theta _s When it is large and when braking, that is, when the braking signal S _br is input, the above lock control is not performed. That is, the current i is set to zero and the hydraulic oil P is set to zero.

(Effects of the Invention) As described above, in the power transmission device of the present invention, even if there is a manual input for locking the torque distribution means, the torque distribution means is not locked under a constant traveling condition. Therefore, when the torque distribution means is locked, in a traveling state in which running stability, turning performance, braking performance, or the like may occur,
It is possible to reliably prevent the torque distribution means from being locked. That is, there is an effect that it is possible to suppress the undesirable behavior change of the vehicle due to the locking of the torque distribution means.

[Brief description of drawings]

FIG. 1 is a schematic diagram showing the configuration of the present invention, FIG. 2 is an overall configuration diagram showing an example in which the present invention is applied to a four-wheel drive vehicle, and FIG. 3 is mainly a hydraulic control system in the example of FIG. Configuration diagram shown, No. 4
FIG. 5 is a characteristic diagram showing the amount of transmitted torque with respect to the rotational speed difference, FIG. 5 is a flow chart showing an example of the control operation in the example of FIG. 2, and FIG. FIG. 7 is a configuration diagram showing the differential device and its hydraulic control system in FIG. A ... Torque distribution means, B ... Input means, C ... Locking means, D ... Running state detecting means, E ... Inhibiting means.

Claims (1)

[Claims] 1. A torque distribution means for distributing torque between right and left or front and rear wheels, input means for inputting a command for prohibiting the operation of the torque distribution means, and operation when the command is input. However, when the locking means for directly connecting both wheels to which torque is distributed by the torque distribution means, the traveling state detecting means for detecting the traveling state of the vehicle, and the detected traveling state coincides with a predetermined state, A power transmission device for a vehicle, comprising: a prohibiting unit that prohibits the operation of the locking unit even when the command is input.