JPS6259127A - Transmission torque controller for four-wheel drive car - Google Patents

Abstract

PURPOSE:To improve the traveling stability and turning performance on steering by controlling the torque transmission quantity of a power transmission means in accordance with the steering ratio characteristic between the front and rear wheels of a 4-wheel steering mechanism and controlling the torque distribution ratio between the front and rear wheels. CONSTITUTION:In a four-wheel driving mechanism D, a front side propeller shaft 4 is connected to the output shaft 2 of a power plant 1 through a gear train 3, and a rear side propeller shaft 6 is connected through a hydraulic type variable clutch 5 as power transmission means. The torque distribution ratio between front and rear wheels 8 and 10 is adjusted by varying the transmission torque quantity of the clutch 5 by varying the pressure of the working oil supplied into the clutch 5. In this case, a hydraulic control valve 13 is controlled by a control unit 14 on the basis of the signal Sk representing the steering ratio (ratio of the rear-wheel steering angle to the front-wheel steering angle) obtained by a controller not shown in the figure, and the pressure of the working oil applied onto the clutch 5 is varied.

Description

Detailed Description of the Invention (Industrial Application Field) The present invention relates to a transmission torque control device for a four-wheel drive vehicle, and more particularly to a transmission torque control device for a four-wheel drive vehicle combined with a four-wheel steering mechanism. Regarding a control device.

(Prior art) As a 4-wheel drive vehicle, the fallen tree was developed in 1983-122630.
As shown in the publication, a first drive shaft is directly connected to a power plant consisting of an engine, a transmission, etc., and a second drive shaft is connected to the power plant via a power transmission means such as a clutch mechanism. There is known a vehicle that can switch between two-wheel drive and four-wheel drive by controlling the engagement and release of the clutch mechanism.

To adjust the torque distribution ratio between front and rear wheels in a four-wheel drive vehicle,
For example, this can be done by adjusting the engagement force of a clutch mechanism that switches between two-wheel drive and four-wheel drive as described above, and controlling the amount of torque transmitted by this clutch mechanism.

On the other hand, as a four-wheel steering mechanism, for example,
As disclosed in Publication No. 457, the ratio of the rear wheel steering angle to the front wheel steering angle is determined according to the vehicle speed, and includes a front wheel steering mechanism that steers the front wheels and a rear wheel steering mechanism that steers the rear wheels. It is known to change the steering ratio according to a predetermined steering ratio characteristic so that the slip angle of the vehicle is always zero. Further, this four-wheel performance mechanism and the above-mentioned four-wheel drive device may be combined and equipped.

Here, the steering ratio characteristic that makes the slip angle of the vehicle zero is such that at low speeds, the rear wheels steer in the opposite direction (opposite phase) to the front wheels, improving turning performance and reducing the minimum turning radius. At high speeds, the rear wheels steer in the same direction (same phase) as the front wheels, improving maneuverability and allowing smooth lane changes.

(Object of the Invention) The present invention provides a transmission torque control device for a four-wheel drive vehicle combined with a four-wheel steering mechanism as described above, which controls the torque distribution ratio between the front and rear wheels according to the steering ratio characteristics of the front and rear wheels. However, it is an object of the present invention to provide a transmission torque control device for a four-wheel drive vehicle that can improve running stability and turning performance during steering depending on the running condition of the vehicle.

(Structure of the Invention) The present invention is combined with a four-wheel steering mechanism that controls steering of the rear wheels according to a steering ratio characteristic that ranges from the opposite phase to the same phase as the front wheels. At least one of the respective torque transmission paths is provided with a power transmission means that can vary the amount of torque transmission, and this power transmission means is variably controlled to control torque distribution to the front and rear wheels.
A transmission torque control device for a wheel drive vehicle, comprising: a steering ratio signal generating means for generating a steering signal indicating a steering ratio of front and rear wheels of the four-wheel steering mechanism; The present invention is characterized by comprising a control means for controlling the amount of torque transmitted by the power transmission means based on the above, and thereby controlling the torque distribution ratio between the front and rear wheels.

(Effect of the invention) In the transmission torque control device for a four-wheel drive vehicle of the present invention,
As described above, the torque transmission amount of the power transmission means is controlled according to the steering ratio characteristics of the front and rear wheels of the four-wheel steering mechanism, and thereby the torque distribution ratio of the front and rear wheels is controlled.
Driving stability and turning performance during steering are improved depending on the driving condition of the vehicle. For example, in high-speed driving conditions, the steering ratio characteristics of the front and rear wheels are set to be in the same phase for driving stability, but the torque distribution ratio of the front and rear wheels is adjusted accordingly so that the amount of torque transmitted to the rear wheels is increased. controlled by. In addition, in the steering state when the steering angle is large, the steering ratio characteristics of the front and rear wheels are set in opposite phases in order to improve the turning performance of the vehicle. is controlled so that the torque transmission rate to the front wheels is increased.

(Embodiments) Hereinafter, a transmission torque control device for a four-wheel drive vehicle combined with a four-wheel steering mechanism according to a preferred embodiment of the present invention will be described with reference to the accompanying drawings.

1 and 2 show a four-wheel drive mechanism according to an embodiment of the present invention. In FIG. 1, reference numeral 1 indicates a power plant, and this power plant 1 consists of an engine, a transmission, etc. The output shaft 2 of this power plant 1 has a gear train 3.
A front propeller shaft □ is connected to the front propeller shaft 4 via a hydraulic variable clutch 5 which is a power transmission means □, and a rear propeller shaft 6 is connected via a hydraulic variable clutch 5 which is a power transmission means □. The front propeller shaft 4 connects to the front wheels 8 via a final gear unit 7, and the rear propeller shaft 6 connects to the rear wheels 1 via a final gear unit 9.
0 respectively. In the above configuration, the pressure of the hydraulic oil applied to the clutch 5 is changed to change the amount of torque transmitted by the clutch 5, thereby adjusting the torque distribution ratio between the front and rear wheels.

Next, a hydraulic control system for the clutch 5 will be explained with reference to FIG. As shown in the figure, the hydraulic oil in the oil tank 11 is sucked up by the pump 12,
It is discharged at a predetermined pressure and supplied to the hydraulic oil chamber 5a of the clutch 5 via the hydraulic control valve 13. The hydraulic control valve 13 is controlled by a control unit 14 to adjust its working hydraulic pressure. As a result, the pressure of the hydraulic oil in the hydraulic oil chamber 5a of the clutch 5 is adjusted, and the engagement force of the clutch 5 is controlled.

The control unit 14 is provided with a driving state detection means 15 that detects the driving state of the vehicle, such as vehicle speed and steering angle. This control unit 14 receives an output signal from the running state detection means 15, and determines the control current l according to the running state indicated by this output signal. This control current l
is supplied to the hydraulic control valve 13, which, in response to the control current 1, generates a pressure P proportional to the current i.
of hydraulic oil is supplied to the clutch 5. The clutch 5 is engaged at a pressure corresponding to the pressure P of the hydraulic oil, and transmits a torque Tr proportional to the engagement pressure to the rear propeller shaft 6.

On the other hand, FIG. 3 shows the overall configuration of a four-wheel steering system S for a vehicle, and reference numeral 21 denotes a front wheel steering mechanism that steers the left and right front wheels 8. , a rack and pinion mechanism 24 that converts the rotational motion of the steering handle 23 into linear motion, and left and right tie rods 25 and knuckles that transmit the operation of the rack and pinion mechanism 24 to the front wheels 8 and steer them left and right. It consists of an arm 26.

Reference numeral 27 denotes a rear wheel steering mechanism for steering the left and right rear wheels 10, and the rear wheel steering mechanism 27 has both ends connected to the left and right rear wheels 10 via tie rods 29 and knuckle arms 30. A rear wheel imitation rod 31 extending in the direction is provided. A rack 32 is formed on the rear wheel operating rod 31;
The binion 33 that meshes with the rack 32 is the pulse motor 3.
4, a pair of bevel gears 35, 36 and a pinion shaft 37
The pulse motor 34
The rear wheels 10 are configured to be steered left and right in accordance with the direction and amount of rotation.

Further, a power cylinder 38 is connected to the rear wheel operating rod 31, with the rod 3I serving as an operating rod.

The power cylinder 38 has a left-turning hydraulic chamber 38b and a right-turning hydraulic chamber 38c partitioned in the vehicle width direction by a piston 38a fixed to the rear wheel operation loft 31, and the eight hydraulic chambers 38b, 38c are Hydraulic passage 3 respectively
9a139b, it communicates with a control valve 40 that controls the oil supply direction and oil pressure to the power cylinder 38, and a hydraulic pump 43 is connected to the control valve 40 via an oil supply passage 41 and an oil return passage 42. The hydraulic pump 43 is rotationally driven by a motor 44. The control valve 40 is connected to the pinion shaft 3
7 is detected, and when the rear wheels 10 are steered to the left (counterclockwise in the figure), the oil supply passage 41 is communicated with the left-turn hydraulic chamber 38b, and the right-turn hydraulic chamber 38c is returned with oil. Road 3
On the other hand, when the rear wheels 10 are steered to the right (clockwise in the figure), the communication state is reversed to that described above, and at the same time, the hydraulic pressure from the hydraulic pump 43 is applied according to the rotational force of the pinion shaft 37. The pulse motor 34 operates the bevel gears 35 and 36, the pinion shaft 37, and the pinion 33.
When the rear wheel operating rod 31 is moved in the axial direction (vehicle width direction) via the clutch 32, the power cylinder 3
The movement of the rear wheel operating rod 31 is assisted by supplying pressure oil to the rear wheel operating rod 8.

The operation of the pulse smoke 34 and the drive motor 44 of the hydraulic pump 43 is controlled by a control signal output from a controller 45 which is a control section of the rear wheel steering mechanism 27. The controller 45 includes a front wheel steering mechanism 2
A steering angle signal from a steering angle sensor 46 that detects the front wheel turning angle based on the amount of steering of the steering wheel 23 at 1, and a vehicle speed signal from a vehicle speed sensor 47 that detects vehicle speed are input to the battery power source 49. is connected.

As shown in FIG. 4, the controller 45 receives a steering angle signal from a steering angle sensor 46 and a vehicle speed sensor 47.
a target steering angle calculation unit 51 that receives a vehicle speed signal from the vehicle and calculates a target steering angle of the rear wheels corresponding to the front wheel steering angle and the vehicle speed from the steering ratio characteristics stored in the characteristic storage unit 50; A pulse generator 52 that outputs a pulse signal corresponding to the target steering angle calculated by the steering angle calculating section 51, and a motor for driving the pulse motor 34' and the hydraulic pump 43 in response to the pulse signal from the pulse generator 52. 44, and a driver 53 for converting the signal into a drive pulse signal for driving the rear wheel steering angle.
A steering ratio variable means 54 controls the pulse motor 34 and the drive motor 44 of the hydraulic pump 43 so that the rear wheel steering angle becomes the target steering angle by varying the steering ratio (steering ratio) k according to a predetermined steering ratio characteristic. It is configured.

The characteristic storage section 50 stores steering ratio characteristics as shown in FIG. 5, for example. Basically, this steering ratio characteristic is such that as the vehicle speed increases from low to high speed, the steering ratio k approaches zero from a large value in the opposite phase in the negative direction (a state in which the front and rear wheels are steered in opposite directions). The steering ratio k shifts to the same phase in the positive direction at a predetermined vehicle speed V (1 or more in the medium speed range) (
The front and rear wheels are steered in the same direction), and the steering ratio k is set to be large in the same phase in the high speed range.

The controller 45 is also adapted to generate a steering ratio signal Sk indicating the steering ratio k determined by itself. The controller 45 includes the control unit 1
4 is connected, and this control unit 14 receives the steering ratio signal Sb from the controller 45, stores this signal in advance, and determines the torque distribution ratio by referring to the steering ratio-torque distribution ratio characteristic. It has become. As this steering ratio-torque distribution ratio characteristic, for example, one shown in FIG. 6 or FIG. 7 can be used. The characteristics shown in Figure 6 are:
When the steering ratio k of the front and rear wheels is 0, the rear wheel torque distribution value U0 corresponds to the load distribution of the front and rear wheels, and as the value of the steering ratio of the opposite phase increases, the torque distribution value U decreases, and the torque distribution value U of the same phase becomes The torque distribution ratio U is set to increase as the value of the steering ratio increases. In addition, the characteristics shown in FIG. 7 are such that when the steering ratios are in opposite phases, the distribution ratio U is uniformly set to a relatively small value, and when the steering ratios are in the same phase, the distribution ratio U is uniformly set to a relatively large value. This value is set to the value distribution ratio U2.

As described above, for example, in high-speed driving conditions, the steering ratio characteristics of the front and rear wheels are set to be in the same phase for driving stability.
Accordingly, the torque distribution ratio between the front and rear wheels is controlled so that the torque transmission rate of the rear wheels is increased. In addition, in the steering state when the steering angle is large, the steering ratio characteristics of the front and rear wheels are set in opposite phases in order to improve the turning performance of the vehicle. is controlled so that the torque transmission rate to the front wheels is increased.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram showing a drive system of a four-wheel drive vehicle, FIG. 2 is a schematic diagram of a transmission torque control device according to an embodiment of the present invention, and FIG. 3 is an overall diagram of a four-wheel steering system of a vehicle. 4 is a block diagram of the controller, FIG. 5 is a diagram showing steering ratio characteristics in the case of steering ratio control based on vehicle speed in the controller, and FIGS. 6 and 7 are diagrams of the control unit, respectively. It is a figure which shows the example of the steering ratio-torque distribution ratio characteristic for performing torque distribution ratio control of front and rear wheels by a steering ratio in . D... Four-wheel drive mechanism, S... Four-wheel steering device, 1... Power plant, 2...
Output shaft, 4...Front side propeller shaft,
5...Clutch, 6...Rear side propeller shaft, 13...Hydraulic pressure control valve, 14...
...Control unit, 45...Controller.

Claims (1)

[Claims] It is combined with a four-wheel steering mechanism that controls the steering of the rear wheels according to a steering ratio characteristic that ranges from the opposite phase to the same phase as the front wheels.
At least one of the torque transmission paths that transmits torque from the power plant to the front and rear wheels is provided with a power transmission means that can change the amount of torque transmission, and the power transmission means is variably controlled to control torque distribution to the front and rear wheels. A transmission torque control device for a four-wheel drive vehicle, comprising a steering ratio signal generating means for generating a steering ratio signal indicating a steering ratio of front and rear wheels of the four-wheel steering mechanism, and receiving the steering ratio signal; 4, comprising a control means for controlling the amount of torque transmitted by the power transmission means based on this signal, thereby controlling the torque distribution ratio between the front and rear wheels;
Transmission torque control device for wheel drive vehicles.