JPS6118566A - Steering force controller for power steering system - Google Patents

Abstract

PURPOSE:To achieve sufficient steering response corresponding with the car speed by providing means for producing hydaulic pressure corresponding with the car speed in the reaction chamber and the rack guide pressurizing chamber. CONSTITUTION:Upon entering into high speed travel condition, smaller current is fed to a solenoid 65 when compared with that under low speed traveling, to displace a control spool 67 downward thus to increase the repellent force of spring 69. Consequently, the hydraulic pressure in a feed path 63 is set at high level. While main spool 59 will displace to the position corresponding with the pilot pressure thus to set the pressure in first feed path 57 at high level. Since high pressure in the path 63 is fed into the pressure chamber 36 and the rack pressurizing chamber 44, pushing forces of rack guide 41 and plunger 34 respectively against the rack shaft 14 and the projected section 30 will increase. Consequently, the torsion bar 25 is never twisted by small steering torque thus to increase the rigidity at the servo section.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a steering force control device for a power steering device equipped with a reaction force mechanism to which hydraulic pressure is supplied according to vehicle speed, etc.

<Prior Art> Conventionally, a system is known in which hydraulic pressure proportional to vehicle speed, etc. is applied to a reaction force mechanism to control the steering force of a power steering device in accordance with vehicle speed, etc. In such a known device, one of a pair of valve members operated by manual steering torque is accommodated so as to be movable in the radial direction of the valve member within a reaction force plunge, and the other is provided with a recessed portion in which the plunger engages. A reaction force device that introduces hydraulic pressure proportional to vehicle speed, etc. to the back of the plunger, and a rack guide that is slidably stored in a rack guide pressurizing chamber at the meshing position of the rack shaft and pinion shaft. There is a rack guide pressurizing device that introduces hydraulic pressure proportional to the vehicle speed and presses the rack shaft toward the binion shaft using the rack guide, and one of the above devices has been applied to a power steering device.

<Problems to be Solved by the Invention> A power steering device to which only the above-described reaction force device is applied is such that steering torque input from the steering wheel is transmitted to the pinion shaft via the steering shaft and torsion bar, and Since the reaction force is transmitted to the pinion shaft via the shaft and plunger, the rigidity of the servo valve part is increased, but if there is any play between the rack shaft and pinion shaft, not only will the desired steering response not be obtained, There was a problem that the rotation of the pinion shaft was not immediately transmitted to the rack shaft.

On the other hand, a power steering system using only a rack guide pressurizing device can eliminate play between the rack shaft and pinion shaft, but even with low steering torque, the torsion bar twists, making it difficult to obtain the desired steering response when the steering wheel is in its neutral state. There was a problem with not being able to get it.

Means for Solving the Problems The present invention has been made to solve the problems described above, and is a reaction force mechanism in which a reaction force piston is slidably inserted into the reaction force chamber. A reaction force device that prevents relative rotation between the input shaft and the pinion shaft according to the pressure of the supplied fluid, and a rack guide that is slidably fitted into the rack guide pressurizing chamber. a rack guide pressurizing device that presses the rack shaft toward the pinion shaft according to the pressure of the fluid applied to the vehicle; and a pressure generating means that generates fluid pressure in the reaction force chamber and the rack guide pressurizing chamber according to the vehicle speed, etc. It is characterized by having the following.

<Function> With the above-described configuration, fluid pressure corresponding to the vehicle speed, etc. is introduced into the reaction force chamber and the rack guide pressurizing chamber, and the reaction piston prevents relative rotation between the input shaft and the pinion shaft. The rack shaft is pushed toward the pinion shaft by the guide,
Steering force changes depending on vehicle speed, etc.

<Example> Embodiments of the present invention will be described below based on the drawings.

In FIG. 1, reference numeral 10 denotes a gear housing that forms the main body of the power steering device.A pinion shaft 11 is rotatably supported on this gear housing 10, and this pinion shaft 11 is slidable in a direction intersecting with the gear housing 10. The rack shaft 14 is meshed with the rack shaft 14. Both ends of the rack shaft 14 are connected to steering wheels via a required steering linkage, and a piston of a power cylinder (not shown) is operatively connected to the rack shaft 14.

A valve housing 18 is fixed to the gear housing 10, and a rotary type servo valve 20 is disposed within the valve housing 18.
is stored. The rotor-type servo valve 20 is composed of a sleeve valve member 21 and a rotor valve member 22 that are relatively rotatable about the axis of the pinion shaft 11, and the rotor valve member 22 is connected to a steering shaft (input (shaft) 24. Steering shaft 24
is flexibly connected to the pinion shaft 11 via a torsion bar 25.

A plurality of port grooves 21a and 22a are formed at equal angular intervals on the circumference on the inner circumference of the sleeve valve member 21 and the outer circumference of the rotor valve member 22, and the relative rotation of the sleeve valve member 21 and the rotor valve member 22 causes The supply boat 26 is connected to one of the supply and discharge boats 28 and 29 connected to both chambers of the power cylinder, and the other is communicated to the discharge port 27.

As shown in FIG. 2, protrusions 30 are formed on both sides of the pinion shaft 11 of the rotor valve member 22 in the radial direction, and the pinion shaft 11 corresponding to the protrusions 30 has protrusions A fitting groove 31 is formed in which the fitting groove 30 is loosely fitted so as to be rotatable through several angles around the axis of the steering shaft 24. An engagement groove 32 having a V-shaped cross section is formed on the outer peripheral surface of the protrusion 30.
An insertion hole 33 is formed in the pinion shaft 11 in the radial direction at a position corresponding to the engagement groove 32 when the servo valve 20 is in a neutral state. A plunger 34 that engages with the engagement m32 is inserted into the insertion hole 33 so as to be slidable in the radial direction.
An annular groove 35 is formed on the outer periphery of the pinion shaft 11 to guide hydraulic oil to the rear part of the pinion shaft 11. Insertion hole 33 and annular groove 35
A reaction force chamber 36 is configured.

A cylinder hole 40 is formed in the gear housing 10 in a direction perpendicular to the axis of the rack shaft 14 on the opposite side of the meshing portion between the pinion shaft 11 and the rack shaft 14, and the rack shaft 14 is received in the cylinder hole 40. A receiving rack guide 41 is slidably fitted therein. On the other hand, an end camp 42 is liquid-tightly screwed onto the outer end of the cylinder hole 40, and a pressure spring 43 is provided between the end cap 42 and the rack guide 41 to press the rack shaft 14 toward the pinion shaft 11. It is interposed. Cylinder hole 40, end cap 4? A rack guide pressurizing chamber 44 is configured.

Next, a pressure control circuit for the fluid introduced into the reaction force chamber 36 and the rack guide pressurizing chamber 44 will be described.

50 is a supply pump 5 driven by an automobile engine.
0, and the discharge port of this supply pump 50 is connected to the supply port 2 via a flow rate control valve 51 and a pressure control valve 52.
6. The flow rate control valve 51 has a spool 55 that slides in the valve chamber 54 due to the pressure difference before and after the fixed throttle 53, and the sliding of the spool 55 adjusts the opening degree of the bypass passage 56 to eliminate excess flow. Bypass passage 56
The supply flow rate to the servo valve 20 is controlled to be constant. The fluid whose flow rate is controlled by the flow rate control valve 51 is passed through the first supply passage 57 to the pressure control valve 5.
The pressure control valve 52 has a main spool 59 that slides inside the valve chamber 58, and the main spool 59 connects the front and rear chambers of the valve chamber 58, which are divided by the main spool 5). A communication path 60 is formed, and a fixed throttle 61 is provided in the middle of the communication path 60.
is provided. The main spool 59 slides within the valve chamber 58 according to the front and rear pressure of the fixed throttle 61, and the supply port 26
Opening and closing the second supply passage 62 leading to the first supply passage 57
The internal pressure is maintained at a predetermined level.

The pressure after the fixed throttle 61 is led to a pilot valve 64 via an introduction passage 63, and this virofft valve 6
4 is a solenoid 65 to which a current is applied according to an input signal such as vehicle speed, and a control spool 67 that is attracted to a yoke 66.
and a hole valve 68. The opening degree of this ball valve 68 is set by the repulsive force of the main spool 59, and the fluid in accordance with the opening degree is released to the tank T.
3 is maintained at a predetermined relief pressure. Further, the pressure after the fixed throttle 61 is led to the reaction force chamber 36 and the second guide pressure chamber 44 via the introduction passage 63.

A pressure cut valve 70 is inserted into the introduction passage 63. This pressure cut valve 70 has a movable spool 71 , and the pressure of the second supply passage 62 acts on the movable spool 71 via the passage 72 . Therefore, when the fluid pressure in the second supply passage 62 increases with the operation of the servo valve 20, the movable spool 71 slides within the valve hole 73 to cut off communication with the introduction passage 63, and the second supply passage 62
The pressure fluctuations within the reaction force chamber 36 and the rack guide pressurization chamber 4
4 has no effect.

The current applied to the solenoid 65 of the pilot valve 64 is controlled by a controller 75, and this control current is set based on signals from a vehicle speed sensor 76 and a steering angle sensor 77. As a result, the reaction force chamber 36 and the rack guide pressurizing chamber 44 have a third
Pressure is generated according to the vehicle speed, as shown by the solid line A in the diagram.
As the steering wheel is turned and the steering angle θ increases, the solid line A shifts to the chain line B, and the pressure increases.

The operation will be explained based on the above-described configuration.

For example, in a low speed running state, the current applied to the pilot valve 64 is large (the control spool 67 is displaced upward and the repulsive force of the spring 69 is reduced, so the introduction passage 64 is
The fluid pressure within 3 is set to a low pressure. Further, the main spool 59 is displaced so that the pressure difference before and after the fixed throttle 61 is reduced, thereby maintaining the fluid pressure in the first supply passage 57 at a low pressure. Since the low fluid pressure in the introduction passage 63 is introduced into the reaction force chamber 36 and the rack guide pressurizing chamber 44, the pressing of the rack guide 41 against the rack shaft 14 is caused by the force and the pressing of the plunger 34 against the protrusion 30. The force is small and the steering wheel can be operated with a small steering force.

After that, when the state of high-speed running is entered, a smaller current is applied to the solenoid 65 compared to when running at low speed, the control spool 67 is displaced downward, and the repulsive force of the spring 69 is increased, so that the fluid pressure in the introduction passage 63 is reduced. is set to a higher pressure than when driving at low speeds.

Further, the main spool 59 is displaced to a position corresponding to this pilot pressure, and the pressure in the first supply passage 57 is set to a high pressure. Since the high pressure in the introduction passage 63 is introduced into the reaction force chamber 36 and the rack guide pressurizing chamber 44, the pressing of the rack guide 41 against the rack shaft 14 results in a force and a pressure on the protrusion 30 of the plunger 34. Pushing has a lot of force. As a result, the steering torque applied manually from the steering wheel is transmitted to the pinion shaft 11 via the steering shaft 24 and the torsion bar 25, and is also transmitted to the pinion shaft 11 via the steering shaft 24 and the plunger 34, so that the torsion bar 25 provides a small steering wheel. The rigidity of the servo valve part is increased without being twisted even by torque. Also, since the rack guide 41 pushes the rack shaft 14 in a direction that eliminates play with the pinion shaft 11, rotation of the pinion shaft 11 is prevented. can be transmitted to the rack shaft 14 immediately, and the pinion shaft 11
pinion shaft 11 and rack shaft 1.
The rigidity of the meshing part with 4 is increased. As a result, the rigidity of the entire steering gear is increased, and the desired steering response can be obtained.

Note that if the steering wheel is suddenly operated even when the vehicle is traveling at low or high speed, the servo valve 20 is activated and the pressure in the first supply passage 57 and the second supply passage 62 increases rapidly. However, when this pressure exceeds the set pressure, the movable spool 71 operates to cut off the flow of fluid from the pressure control valve 52, thereby counteracting the effects of large pressure fluctuations in the first supply passage 57 and second supply passage 62. The force chamber 36 and the rack guide pressurizing chamber 44 are not significantly affected.

The present invention is not limited to the above-mentioned embodiments, but the fourth embodiment
As shown in the figure, the reaction piston 8
1 is axially movably connected via a pin 82, and a reaction force receiver 84 integral with the input shaft 83 and a conical recess 84a are provided in the reaction piston 81.

81a are formed at multiple locations on the circumference, and the recessed portions 84a,
A ball 85 is engaged with the concave portion 81a, and the fluid discharged from the pump 90 is connected to a first flow rate control valve to control the pressure of the fluid supplied to the rack guide pressurizing chamber 87 and the reaction force chamber 86. 91, the flow rate Q1 is controlled to be a certain amount larger than the flow rate required for the power steering device, and the flow rate Q+ is further controlled by the second
The flow rate Q required for the power steering device is controlled by the flow rate control valve 92 of
2, the remaining constant flow rate Q3 is bypassed from the bypass passage, and this bypassed fluid is passed through the electromagnetic relief valve 93.
The pressure may be controlled according to the vehicle speed or the like and guided to the rack guide pressurizing chamber 87 and the reaction force chamber 86.

<Effects of the Invention> Rack guide pressurization is achieved using a reaction force device that prevents relative rotation between the input shaft and pinion shaft according to the pressure of the supplied fluid, and a rack guide that is slidably fitted into the rack guide pressurization chamber. A rack guide pressurizing device that presses the rack shaft toward the pinion shaft according to the pressure of the fluid supplied to the pressure chamber, and a rack guide pressurizing device that generates fluid pressure according to the vehicle speed, etc. in the reaction force chamber and the rack guide pressurizing chamber. Since the pressure generating means is provided, the rigidity of the entire steering gear is increased, and sufficient steering response corresponding to the vehicle speed etc. can be obtained. Further, there is an advantage that the steering torque input from the input shaft can be directly transmitted to the pinion shaft.

[Brief explanation of the drawing]

The drawings show an embodiment of the present invention, and FIG. 1 is a sectional view of a power steering device with a hydraulic system diagram, and FIG.
3 is a diagram showing the relationship between vehicle speed, steering angle, and pressure; FIG. 4 is a sectional view of a power steering device as another embodiment of the present invention, and a hydraulic system is shown in FIG. A diagram accompanying the figure. 11.80... Pinion shaft, 14... Rack shaft, 2
0...Servo valve, 21...Sleeve valve member, 22.
...Rotor valve member, 24.83...Steering shaft (input shaft)
, 25... Torsion bar, 32... Engagement groove, 34
...Plunger, 36.86...Reaction force chamber, 41...
- Rack guide, 44.87... Rack guide pressurization chamber, 50°90..., Supply pump, 51... Flow rate control valve, 52... Pressure control valve, 64... Pilot valve, 7D ... Pressure heel valve, 75 ... Controller, 76 ... Vehicle speed sensor, 77 ... Steering angle sensor, 8
DESCRIPTION OF SYMBOLS 1... Reaction piston, 82... Bottle, 84... Reaction force receiving part, 81a, 84a... Recessed part, 85... Ball, 91... First flow control valve, 92 . . . second flow control valve, 93 . . . electromagnetic relief valve.

Claims (1)

[Claims] (1) Power equipped with a servo valve that is operated based on the relative rotation between the input shaft and pinion shaft and controls the supply and discharge of pressure oil to the power cylinder, and a reaction force mechanism that changes the steering wheel torque according to vehicle speed, etc. In the steering force control device for a steering device, the reaction force mechanism controls the input shaft and the pinion shaft according to the pressure of fluid supplied to the reaction force chamber by a reaction piston slidably inserted into the reaction force chamber. The rack shaft is moved toward the pinion shaft in response to the pressure of the fluid supplied to the rack guide pressurization chamber by a reaction force device that prevents relative rotation between the rack guide and the rack guide, which is slidably fitted into the rack guide pressurization chamber. A steering force control device for a power steering device comprising a rack guide pressurizing device for pressing, and a pressure generating means for generating fluid pressure in the reaction force chamber and the rack guide pressurizing chamber according to vehicle speed, etc.