JPS6343870A - Power steering device having control part for distributing torque for four-wheel-drive vehicle - Google Patents

Abstract

PURPOSE:To enable a vehicle to eliminate its corner braking phenomenon generated in accordance with steering of the vehicle, when it is driven running by four wheels, by providing a torque distribution control part, which operates interlocking to the action of a steering force control part, in a single hydraulic control device. CONSTITUTION:A fixed quantity unit 1, for continually holding a stable feed amount of flow, is connected with the delivery side of a supply pump P, and a fixed flow amount of pressure oil, fed out from said fixed quantity unit 1, is supplied to a flow dividing control valve 2. And this flow dividing control valve 2 allows the pressure oil to flow dividedly into the first pressure oil passage 31, which supplies the oil to a steering power cylinder 330 through a steering force control part 30, and into the second pressure oil passage 32 which supplies the oil to a torque distributing control part 40 for a four-wheel-drive vehicle. The steering force control part 30, which is actuated by a relative rotation between input and output shafts of steering force, is constituted so as to adjust a pressure of the pressure oil in the first pressure oil passage 31 is accordance with a change of said relative rotation, while the torque distributing control part 40 is constituted so as to adjust a pressure of the pressure oil in the second pressure oil passage 32 in accordance with a change of the above described relative rotation.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention is designed to reduce the amount of one herk of drive transmitted from the front wheel drive system to the rear wheel drive system during a four-wheel drive turn of a four-wheel drive vehicle. The present invention relates to a power steering system having a torque distribution control section for a four-wheel drive vehicle that can reduce corner braking by controlling according to the steering angle of the steering wheel.

[Conventional technology] Conventionally, a corner brake ink phenomenon occurs when a four-wheel drive vehicle makes a four-wheel drive turn (due to the rotation difference between the front wheels and the rear wheels, the front wheels are under-rotated and drag, and the rear wheels are over-rotated). As a prior art technique for avoiding the phenomenon of force slipping and dispersion, for example, there is a configuration disclosed in Japanese Patent Application Laid-open No. 109-131-1983. According to this prior art, a hydraulic clutch is provided between the drive systems for the front wheels and the rear wheels for connecting and disconnecting the two drive systems, and a nuclear oil J
1 Consists of a pressure oil circuit that supplies pressure oil to the clutch, and a solenoid installed in the pressure oil circuit that opens and closes the pressure oil circuit based on the relationship between the vehicle speed and the steering angle of the steering wheel, which prevents corner brake ink from occurring. When conditions are favorable,
A configuration is shown in which a solenoid is electrically controlled based on information from a vehicle speed sensor and a steering wheel angle sensor to disengage the hydraulic clutch and control switching from four-wheel drive to two-wheel drive.

[Problems to be solved by the present invention] The conventional configuration for controlling switching from four-wheel drive to two-wheel drive has four
With the introduction of four-wheel drive vehicles, vehicle speed sensors and steering angle sensors are used to electrically detect when a corner brake ink phenomenon occurs due to the relationship between vehicle speed and steering angle. It is necessary to set up devices such as a microcomputer, a solenoid, and a controller for electronically controlling the operating timing of the solenoid, as well as control software, which inevitably increases the cost of the entire device.

SUMMARY OF THE INVENTION An object of the present invention is to provide a low-cost device that reduces the corner brake ink phenomenon that occurs when driving a four-wheel drive vehicle.

Means for Solving Problem F] The power steering device having a torque distribution control section for a four-wheel drive vehicle according to the present invention includes a supply pump that delivers a certain amount of pressure oil, and a supply pump that supplies the pressure oil from the supply pump. Due to the relative rotation between the steering force input shaft and the steering force output shaft, the flow control valve divides the flow into the first pressure oil passage that supplies the steering power cylinder and the second pressure oil passage that supplies the four-wheel drive hydraulic clutch. A steering force control unit that is operated to increase or decrease the pressure oil pressure in the first pressure oil passage in accordance with an increase or decrease in the relative rotation; and a steering force control unit that increases or decreases the pressure oil pressure in the second pressure oil passage in accordance with an increase or decrease in the relative rotation. The present invention is characterized in that it has a hydraulic control device having a torque distribution control section.

The power steering device having the torque distribution control section for a four-wheel drive vehicle of the present invention configured as described above is such that when the four-wheel drive vehicle is in four-wheel drive mode, the steering input shaft of the power steering device according to the steering wheel operation is controlled. Pressure oil is supplied from the first pressure oil passage to the power cylinder by a steering force control section that operates according to an increase or decrease in the relative rotation angle between the steering output shaft and the steering output shaft. At the same time, the torque distribution control section can control the hydraulic pressure in the second pressure oil passage that operates on the hydraulic multi-disc clutch. In addition, when both the front and rear wheels are driven, it is possible to control the amount of drive torque distributed to the rear wheels, reduce the drive torque, and eliminate the corner brake ink phenomenon. .

[Operation of the Invention] When the four-wheel drive vehicle is in four-wheel drive, the supply pump is operated by the engine drive nozzle and sends out pressurized oil. The pressure oil sent out from the supply pump is introduced into the branch control valve with a constant flow rate maintained at all times by the flow control valve.

The pressure oil from the supply pump is divided into a pressure oil flow directed to the steering force control unit via the first pressure oil passage by this flow control valve, and a pressure oil flow directed from the separation control valve to the torque distribution control unit via the second pressure oil passage. It is divided into two parts: oil flow and oil flow. In this state: (1) When the four-wheel drive vehicle is traveling straight ahead in four-wheel drive, the steering force input shaft and the steering force output shaft are maintained in a neutral state. Therefore, the steering force control section maintains a state in which the flow of pressure oil corresponding to straight-ahead traveling of the four-wheel drive vehicle is controlled. That is, the steering force control section connects the first pressure oil passage to the reservoir via the drain passage. As a result, the pressure oil that has flowed into the steering force control section from the first pressure oil passage returns to the reservoir from the drain passage. Further, the steering force control section returns the pressure oil from the supply pump to the reservoir tank, thereby maintaining the state in which the pressure oil is not supplied to the power cylinder. Further, the torque distribution control section maintains a state in which the opening area of the second pressure oil passage is minimized, so that the hydraulic pressure acting on the hydraulic multi-disc clutch from the second oil pressure passage is kept constant. Therefore, the hydraulic multi-disc clutch maintains a directly connected state.

(2) Also, when the four-wheel drive vehicle is traveling in four-wheel drive, if the power steering device is activated by operating the steering wheel and the four-wheel drive vehicle turns to the right or left, the steering force input shaft Relative rotation with the steering output shaft occurs. As a result, the steering force control section and the torque distribution control section maintain a state in which they control the flow of pressure oil corresponding to cornering of the four-wheel drive vehicle.

That is, the steering force control section communicates the first pressure oil passage with the power cylinder. Then, the pressure oil in the first pressure oil passage is supplied to the power cylinder while its flow rate is controlled by the steering control section. Further, the flow rate of the pressure oil supplied from the first pressure oil passage to one pressure action chamber of the power cylinder is determined by the opening area controlled by the steering force control section. At the same time, the discharged oil from the other pressure chamber of the power cylinder is discharged to the reservoir, and the power assist force of the power cylinder facilitates steering.

The torque distribution control section controls the amount of increase in the opening area of the second pressure oil passage. Then, the torque distribution control section changes the drain flow rate of the pressure oil in the second pressure oil passage to the reservoir and controls the pressure of the pressure oil acting on the hydraulic multi-disc clutch. As a result, the acting force of the pressure oil from the second pressure oil passage to the hydraulic multi-disc clutch is reduced, and the hydraulic multi-disc clutch reduces the ability of the hydraulic multi-disc clutch to transmit driving force to the rear wheels. That is, during four-wheel drive driving, the torque distribution control section maximizes the amount of drive torque distributed to the rear wheel drive system when the steering angle is zero. Further, as the steering angle of the steering wheel becomes larger than zero, the relative rotation angle between the input shaft and the output shaft of the steering force control section gradually increases, and the frontage area of the second pressure oil passage by the torque distribution control section also increases. . Then, this minute, the second.
The pressure oil in the rf oil passage increases the drain flow rate to the reservoir by the torque distribution control section. In addition, the acting force of pressure oil on the hydraulic multi-disc clutch becomes weaker, the amount of drive torque distributed to the drive system on the rear wheels (two wheels) side decreases, and the hydraulic multi-disc clutch reduces the rotation difference between the front and rear wheels. absorb.

[Effect] As described above, according to the power steering device having a torque distribution control section for a four-wheel drive vehicle of the present invention, a torque distribution control section that is interlocked with the operation of the steering force control section of the hydraulic control device is disposed. There is.

As a result, the steering force I! The power assist force for steering can be controlled by the II control part, and the torque distribution control part can control the force of the pressure oil applied to the hydraulic multi-disc clutch, and the drive torque to the rear wheel drive system. 1. Absorbs the rotational difference caused by the inner wheel difference between the front and rear wheels of a four-wheel drive vehicle by reducing the amount of distribution. It is possible to suppress the occurrence of the J-corner braking phenomenon. As a result, when the four-wheel drive vehicle turns in the four-wheel drive state, a good driving condition can be obtained. Further, its configuration does not require the setting of devices such as a vehicle speed sensor, steering angle sensor, controller, microcomputer, etc. and control software as in the past, and can contribute to cost reduction.

[Example] Examples of a power steering device having a torque distribution control section for a four-wheel drive vehicle according to the present invention are shown in FIGS. 1, 2, 3, 4, and 5.
This will be explained based on the diagram.

The power steering device having a torque distribution control section for a four-wheel drive vehicle according to the embodiment includes a supply pump P, a flow control valve 2, and a hydraulic control device 3 as components. Note that the supply pump P and the branch control valve 2 can be conventional ones.

The supply pump P is rotated by the driving force of the vehicle's engine and sends out pressure oil, and also supplies a constant flow rate Q of pressure oil shown in FIG. 3 to a branch control valve 2, which will be described later. The flow rate of the pressure oil sent out from the supply pump P changes depending on the engine speed.

For this reason, the supply pump P has a metering device 1 for always maintaining a stable and constant delivery flow rate regardless of changes in the engine speed. The metering device 1 includes an orifice 12 installed in the middle of a pressure oil passage 11 leading from a supply pump P to a control flow valve 2, and a pressure oil passage 1 installed in front and behind the orifice 12.
1, and a spool 15 installed in the middle of the bypass passage 13 and combined with a push spring 14.
) is slidably housed in a cylindrical housing 1G.
11J of the bypass valve 17, and a return passage 18 which returns the excess flow rate of the pressure oil sent out from the supply pump P to the reservoir T by the operation 11J of the bypass valve 17.

Further, the metering device 1 is operated by the pressure difference between the pressure oil before and after the orifice 12 and the biasing force of the press spring 14, with respect to the flow rate of the pressure oil sent out from the supply pump P, which changes depending on the engine rotation speed. By controlling the amount returned to the bottom of the reservoir by the bypass valve 17, a constant flow mQ of pressure oil can be supplied to the diversion control valve 2.

The flow control valve 2 branches from the pressure oil passage 11 and has an orifice 2.
It is provided with a cylindrical housing 25 that slidably accommodates a control spool 24 combined with a bypass passage 22 and a spring 23. control spool 24
is the pressure difference between the pressure oil before and after the orifice 21 and the push spring 23
It operates with the urging force of. The diversion control valve 2 supplies pressure oil from the supply pump P to a steering power cylinder 330 via a steering force control section 30 (described later) and a first pressure oil passage 31 and a four-wheel drive vehicle torque distribution control section 40. The flow is divided into a second pressure oil passage 32 that supplies the oil to the second pressure oil passage 32. That is, constant flow rates Q1 and Q2 of pressure oil are distributed to the first pressure oil passage 31 and the second pressure oil passage 32, respectively.

The hydraulic control device 3 has a steering force control section 30 and a torque distribution control section 40 in a valve housing B combined with the housing body Δ shown in FIG. The steering force control unit 30 includes a valve housing B and a hollow sleeve valve 3 accommodated in the valve housing B.
10, and a tenth valve 3408 which is disposed within the sleeve valve 310 and is integrally formed with a part of the hollow input shaft 340 which is rotated by operation from the handle. The valve housing B has a high pressure oil port 31 connected to the supply pump P via the first pressure oil passage 31 and the diverter valve 2.
1 and a low pressure oil port 312 connected to the reservoir T, and two switching ports 31 connected to the power cylinder 330.
3.314. Sleeve valve 310 and 10th-
It rotates relative to the taper valve 3408. This sleeve valve 3
As is well known, long grooves (not shown) and land portions (not shown) are formed in the axial direction on the inner and outer circumferential surfaces of the 10 and 10th valves 3408 at intervals in the circumferential direction. The long groove and the land portion keep the high pressure oil port 311 and the low pressure oil port 312 in communication when the steering wheel is in a position that keeps the four-wheel drive vehicle moving straight. Moreover, when the cloth is cut by operating the handle, a phase shift occurs between the long groove and the land portion, and the high pressure oil port 311 and the switching port 31
4, and also communicates the switching port 313 and the low pressure oil port 312. Also, when the handle is turned to the left, the high pressure oil port 311 and the switching port 3 are connected in the same way.
13, and also communicates the switching port 314 and the low pressure oil port 312.

Moreover, the power cylinder 330 forms one pressure action chamber 332 and the other pressure action chamber 333 with the piston 331 as a boundary. Further, one pressure action chamber 332 is connected to the switching port 313 through a passage 334. The other pressure chamber 333 is connected to the switching port 314 by a passage 335 .

The torque distribution control unit 40 includes a high pressure oil port 410 formed in the valve housing B and connected to the second pressure oil passage 32, a low pressure oil port 420 connected to the reservoir T, and a sleeve valve 310 housed in the valve housing B. and a 20th valve 34 , which is disposed inside the sleeve valve 310 and formed integrally with the input shaft 340 . Ob, arranged between the sleeve valve 310 and the 20th valve 340b, and the 20th valve 340b.
b, it consists of a pressure oil control valve 400 that is rotatable relative to the sleeve valve 310. The pressure oil control valve 400 includes a communication hole 402 connected to the second pressure oil passage 32 on the circumference of the cylindrical wall 401 and a flow rate adjustment valve connected to the communication hole 402 on the inner circumference side of the cylindrical wall 401. No. 20-, which is provided with a valve hole 4o3.
The taper valve 340b is provided with a flow rate adjustment protrusion 343 at a position facing the flow rate adjustment valve hole 403. Flow rate adjustment protrusion 34
3 maintains the minimum opening area of the flow control valve hole 403 shown in the cross section of FIG. 2 at the steering wheel position where the four-wheel drive vehicle moves straight. The flow rate adjustment protrusion 343 rotates clockwise and counterclockwise from the position shown in FIG. 2 as the handle is operated to cut the cloth and to the left, thereby increasing the opening area of the flow rate adjustment valve hole 403. Furthermore, an annular passage C is formed between the valve housing B and the sleeve valve 310 from the second pressure oil passage 32 . The annular chamber E formed between the pressure oil control valve 400 and the 20th valve 340b includes the opening 341b of the 20th valve 340b, the hollow portion 3410, the exhaust port 341e, and the pressure oil control valve 400. It communicates with a low-pressure oil port 420 via an exhaust pressure passage 404 formed in the sleeve valve 310 and an exhaust pressure hole 315 formed in the sleeve valve 310 . Hanaki
A second pressure oil passage 32 between the branch control valve 2 and the high pressure oil port 410 is connected to a hydraulic multi-disc clutch 41 via a hydraulic passage 321. That is, the second pressure oil passage 3 is controlled by the torque distribution control section 40.
The pressure oil in 2 is connected to the high pressure oil port 410 and the low pressure oil port 42.
By controlling the amount drained to the reservoir T via the hydraulic multi-disc clutch 41, the pressure of the pressure oil acting on the hydraulic multi-disc clutch 41 can be adjusted. As shown in FIG. 5, the hydraulic multi-plate clutch 41 is disposed on a rotary drive shaft 10 between a front wheel differential w8 and a rear wheel differential 9 of a four-wheel drive vehicle. Note that a known hydraulic multi-disc clutch 41 can be used. The driving force of the engine 6 is transmitted from the transmission 7 to the front wheel differential 8 via the first gear group 71, and rotationally drives the right front wheel 811 and the left front wheel 821 via drive shafts 81 and 82. At the same time, when the hydraulic multi-disc clutch 41 is in the engaged state, the driving torque from the engine 6 is transmitted to the rear wheel differential device 9, and the front wheel differential device 8 transmits the driving torque to the second gear group 72, Hydraulic multi-plate clutch 4
The driving force transmitted to the rear wheel differential W9 through the drive shafts 91 and 92 rotationally drives the right rear wheel 911 and the left rear wheel 921. Further, when the hydraulic multi-plate clutch 41 is disengaged, the driving force from the engine 6 is transmitted only to the right front wheel 811 and the left front wheel 821, and is not transmitted to the right rear wheel 911 and the left rear wheel 921.

The torsion bar 350 housed inside the input shaft 340 has one end 350a connected to the input shaft 340, and the other end 350b connected to an output shaft 360 having a pinion 360a. As a result, the input shaft 340 becomes the output shaft 360.
is flexibly connected. Moreover, the rack tooth 370a of the rack shaft 370 connected to the piston 331 of the steering power cylinder 330 is attached to the pinion 360a of the output shaft 360.
is engaged.

The operation of the power steering system having the torque distribution control section for a four-wheel drive vehicle of the present invention configured as above will be explained.

-16- According to the embodiment of the present invention, when driving in four-wheel drive with the front wheels facing substantially forward by a steering device such as a steering wheel, the rotor valves 340a and 340b slide into the first pressure oil passage 31.
The oil passes through the high pressure oil port 311 and the low pressure oil port 312 of the steering force control unit 30 and is returned to the reservoir T. Therefore, the switching ports 313 and 314 leading to passages 331 and 335 to the power cylinder 310 are at low pressure and equal pressure.

At the same time, the torque distribution control section 40 is in a state in which a slight interval is maintained (see FIG. 2), and the degree of mouth is kept at a minimum. Therefore, the hydraulic pressure in the second pressure oil passage 32 and the pressure oil acting on the hydraulic multi-disc clutch 41 via the hydraulic passage 321 communicating with the second pressure oil passage 132 are also maximized. As a result, the multi-disc clutch 41 is reliably engaged, and the driving force from the front wheel differential device 8 side is reliably transmitted to the rear wheel differential device 9. This driving force rotationally drives the right rear wheel 911 and the left rear wheel 921 via the drive shafts 91 and 92. Therefore, the front wheels and the rear wheels receive the drive from the engine 6 and rotate smoothly.

Here, when the front wheels are steered by operating the steering wheel, the relative rotation between the steering input shaft 340 and the steering output shaft 360 causes the steering force control section 30 and the torque distribution control section 40 to simultaneously rotate in the same direction and at the same angle. , and power cylinder 3
10 is one pressure oil action chamber 332 in the direction of turning the handle.
Alternatively, high pressure oil acts on one of the other pressure oil action chambers 333 to provide an assisting force to the power piston 331, and the torque distribution control section 40 increases the opening area of the second pressure oil passage 32, and The discharge resistance of the pressure oil returned from the second pressure oil passage 32 to the reservoir T via the torque distribution control section 40 decreases by the increased amount. Then, the acting force of the pressure oil on the hydraulic multi-disc clutch 41 decreases. As a result, the hydraulic multi-disc clutch 41 loosely engages in accordance with the acting force of the pressure oil, reduces the distribution of drive torque to the rear wheels, and reduces the amount of drive torque transmitted. That is, the oil pressure acting on the clutch 41 changes as shown by curve A in FIG. 4 with respect to the rotation angle of the handle.

As a result, the four-wheel drive vehicle can reduce the corner braking phenomenon during four-wheel drive driving.

As described above, according to the configuration of the embodiment of the present invention, when a four-wheel drive vehicle is traveling in four-wheel drive, the corner braking phenomenon associated with steering can be controlled by a torque control system installed in one hydraulic control device together with a steering force control section. This problem can be solved by controlling the torque distribution of the hydraulic multi-disc clutch using the distribution control unit.

Furthermore, since only one device is required, the cost can be reduced compared to conventional devices, and the installation space in the vehicle can also be saved.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal cross-sectional view showing a state in which a power steering device having a torque distribution control section for a four-wheel drive vehicle according to the present invention is used. Second
The figure is a cross-sectional view taken along the line (■--I) of the main part in FIG. 1. FIG. 3 is a hydraulic circuit diagram in FIG. 1. FIG. 4 is a diagram showing the relationship between the steering wheel rotation angle and the clutch oil pressure. FIG. 5 is a schematic system diagram showing the driving force transmission system of the four-wheel drive vehicle used in this embodiment. 2... Diversion control valve 4... Torque distribution control section for four-wheel drive vehicle 21... First
Pressure oil passage 22...Second pressure oil passage 5...Hydraulic control device 40...Torque distribution control section 41...Hydraulic clutch P...Supply pump

Claims (1)

[Claims] (1) A supply pump that delivers a certain amount of pressure oil, and a first supply pump that supplies pressure oil from the supply pump to the steering power cylinder.
No. 2, which supplies pressure oil passages and four-wheel drive hydraulic clutches.
A control valve that divides the flow into the pressure oil passage, and a steering system that is operated by relative rotation between a steering force input shaft and a steering force output shaft, and increases or decreases the pressure oil pressure in the first pressure oil passage in accordance with an increase or decrease in the relative rotation. Torque distribution control for a four-wheel drive vehicle, comprising a force control section and a hydraulic control device having a torque distribution control section that increases or decreases the pressure oil pressure in the second pressure oil passage according to an increase or decrease in the relative rotation. A power steering device with a section.