JPS61211166A - Controller for power steering device - Google Patents

Abstract

PURPOSE:To prevent abrupt increase of steering pressure and to maintain stable engine rotation by providing a reaction controller for controlling to increase the reaction of reaction mechanism for varying the steering resistance near the steering end of steering wheel. CONSTITUTION:A servo valve 30 comprised of a rotary valve member 31 integral with the steering shaft 23 and a sleeve valve member 32 fittable rotatably over said member 31 is contained in a hole of valve housing 12 of power steering system. While reaction mechanism where a plunger 54 is inserted into an insertion hole 53 made radially through a pinion shaft 21 and a reaction chamber 56 is arranged in the rear of the plunger 54 is provided. Here, a pressure control valve 70 is coupled to a path 46 for leading the flow controlled to predetermined level through flow control valve 65 to the lead-in port 58 of the reaction chamber 56. The pressure control valve 70 is controlled through reaction controller 100 to increase the reaction near the steering end in accordance to the signal from steering angle sensor 105.

Description

[Detailed Description of the Invention] <Industrial Application Field> The present invention provides a control device for a power steering device that prevents a sudden increase in engine load at the end of steering and the occurrence of abnormal noise due to vibration in a servo valve. Regarding.

<Prior Art> Generally, in a car equipped with a power steering device, a steering torque is applied to the steering wheel to rotate a servo valve, thereby supplying pressurized fluid from a pump to a power cylinder.
The assist force of this power cylinder allows for nimble steering operation.

<Problems to be Solved by the Invention> In such a conventional device, when the piston reaches the stroke end by steering the steering handle to the steering end, the steering pressure increases to the maximum pressure, which causes a sudden increase in the pump load. There have been problems in that the rotation of the engine becomes unstable, causing engine stall, and that the servo valve vibrates and generates abnormal noise due to rapid fluctuations in steering pressure.

Means for Solving the Problems> The present invention has been made to solve the problems of the prior art, and includes a steering angle sensor that detects the steering angle of the steering wheel, and a signal from the steering angle sensor. The present invention is characterized in that a reaction force control device is provided that controls the reaction force of the reaction force mechanism to increase near the steering end of the steering handle.

Effect> Since the present invention has the above configuration, the hydraulic reaction force of the reaction force mechanism is increased in the vicinity of the steering end of the steering handle, thereby restraining the steering of the steering handle.

As a result, sudden fluctuations in steering pressure are suppressed, eliminating sudden increases in pump load, and as a result, instability in engine rotation and accompanying engine stall can be prevented. Further, as the hydraulic reaction force by the reaction force mechanism increases, sudden fluctuations in the steering pressure at the steering end are eliminated, and as a result, vibrations of the servo valve are suppressed, and abnormal noise can be prevented from occurring.

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

In FIG. 1, reference numeral 11 indicates a housing main body forming the main body of the power steering device, and reference numeral 12 indicates a valve housing fixed to the housing main body 11. A pinion shaft (output shaft) 21 is rotatably supported within the housing body 11 and the valve housing 12 via a pair of bearings 13 and 14.
Rack teeth 22a of a rack shaft 22 that is slidable in a direction intersecting the pinion shaft 21 mesh with the pinion shaft 21. This rack shaft 22 is connected to a piston of a power cylinder (not shown), and both ends thereof are connected to steering wheels via a required steering link mechanism.

A servo valve 30 is housed in the large direction of the valve housing 12 . The servo valve 30 has a rotary valve member 31 integrally formed with an input shaft 23 as a steering shaft, and a sleeve valve member 32 fitted to the outer circumference of the rotary valve member 31 concentrically and rotatably relative to each other as main components. There is. The rotary valve member 31 is flexibly connected to the pinion shaft 21 via a torsion bar 24 whose one end is connected to an input shaft 23 integral therewith.

Further, as is well known, a plurality of lands and grooves extending in the axial direction are formed at equal intervals on the outer circumference of the rotary valve member 31, and similarly, on the inner circumference of the sleeve valve member 32, a plurality of lands and grooves extending in the axial direction are formed. A plurality of lands and grooves extending in the direction are formed at equal intervals. Therefore, if the servo valve 30 is in the neutral state, the pressure fluid supplied from the supply port 35 flows evenly into the grooves on both sides of the land portion, and then flows through the communication path 37 and the low pressure chamber 3.
8 and exits via passage 39 to discharge port 36 . In this case, both distribution ports 40,41 are at low and equal pressure, so the power cylinder is not activated.

However, if the servo valve 30 deviates from the neutral state, the distribution action of the servo valve 30 causes the fluid to be supplied to the power cylinder through one distribution hole 40, and the fluid discharged from the power cylinder is supplied to the power cylinder through the other distribution port 41. Communication path 37
, passage 39 and low pressure chamber 38 to be discharged to discharge port 36 .

Further, a reaction force mechanism having the following configuration is incorporated in the valve housing 12. That is, as shown in FIG. 2, a protrusion 50 that protrudes on both sides in the radial direction is formed at the end of the rotary valve member 31, and a protrusion 50 is formed on the pinion shaft 21 corresponding to the protrusion 50. A fitting groove 51 is formed into which the input shaft 23 is loosely fitted so as to be rotatable around the axis of the input shaft 23 by several angles. A tapered engagement groove 52 is formed on the outer circumferential surface of the protrusion 50, and an insertion groove 52 is formed in the pinion shaft 21 at a position corresponding to the engagement groove 52, into which the plunger 54 is slidably inserted in the radial direction. A hole 53 is formed. A reaction force chamber 56 into which fluid pressure is introduced through an annular groove 55 is formed at the rear of the plunger 54, and the plunger 54 is moved into the engagement groove 52 by the fluid pressure introduced into the reaction force chamber 56. It is designed to be pressed.

In addition, 58 is a port for introducing fluid for reaction force control, and 57
is a passage that communicates the port 58 and the annular groove 55.

The reaction force mechanism configured as described above is a so-called radial type in which the plunger is slid in the radial direction, but it may be a thrust type in which the plunger is slid in the axial direction to apply a reaction force.

Reference numeral 60 indicates a supply pump driven by an automobile engine, and a discharge port of this supply pump 60 is connected to the supply port 35 via a first flow control valve 61. The first flow rate control valve 61 is operated according to a metering orifice 62 provided in a passage 45 that connects the discharge boat of the supply pump 60 and the supply boat 35, and the back and forth pressure of this metering orifice 62. Bypass passage 63 is designed to keep the differential pressure across the lever constant at all times.
A certain amount of fluid necessary for the power steering device is supplied to the supply boat 35 by this flow rate control valve 61, and excess flow is bypassed to the bypass passage 63.

The bypass passage 63 of the first flow control valve 61 is connected to the introduction boat 58 of the reaction force chamber 56 via the second flow control valve 65. The second flow control valve 65 has a passage 46 connecting the bypass passage 63 and the introduction port 58.
A metering orifice 66 is provided in the metering orifice 66, and a bypass passage 67 connected to the reservoir is operated according to the pressure before and after the metering orifice 66 to keep the differential pressure between the front and back constant. This second flow control valve 65
The flow rate introduced into the introduction port 58 is controlled to be constant, and the excess flow is bypassed to the reservoir via the bypass passage 67.

A pressure control valve 70 is connected to the passage 46 connecting the second flow rate control valve 65 and the introduction port 58.

As shown in FIG. 3, the pressure control valve 70 includes a valve body 72 fixed to a housing 71, a solenoid 73 attached to the valve body 72, and a movable spool 74 that is displaced when the solenoid 73 is energized. , a valve seat member 76 forming a relief passage 75 that communicates with the introduction port 58, a ball valve 77 that opens and closes the relief passage 75 of this valve seat member 76, and between this ball valve 77 and the movable spool 74. It is composed of a relief pressure setting spring 78 and a balance spring 79 which are inserted. The movable spool 74 is usually a spring 78.
It is held in the down position shown in the figure by the balance of 79, and the spring load of the relief pressure setting spring 78 is set to the maximum. However, as the movable spool 74 is displaced to the right against the balance spring 79 due to the suction action of the solenoid 73, the spring load of the spring 78 is reduced.

In FIG. 1, 100 is a reaction force control device that controls the opening and closing of the pressure control valve 75 to control the hydraulic reaction force generated in the reaction force chamber 56 of the reaction force mechanism. This reaction force control device 100 includes a microprocessor 101, a ROM 102, and a RAM 103.
This microprocessor 101 is connected to the pressure control valve 72 via a solenoid drive circuit 104. A steering angle sensor 105 is also connected to the microprocessor 101, and the steering angle θ of the steering wheel is detected based on an output signal from the steering angle sensor 105.

Control pattern data as shown in FIG. 4 is stored in the ROMI O2. In this data, the control current i to the pressure control valve 70 is set for the steering wheel steering angle θ, and the characteristics of the control current i are as follows: The maximum current is applied while the vehicle is being steered, and the current is then set to a value that gradually decreases as the vehicle is steered beyond this angle range and approaches the steering end ±θE.

Next, the operation of the above mechanism will be explained. supply pump 60
The pressure fluid discharged from the tank is controlled to a predetermined level by the first flow rate control valve 61 and then sent to the supply boat 35 of the power steering device.
supplied to

At the same time, the surplus flow from the first flow rate control valve 61 is controlled to a constant flow rate by the second flow rate control valve 65, and then supplied to the reaction force chamber 56 via the passage 46.

The fluid pressure of the fluid supplied to this reaction force chamber 56 is controlled by a pressure control valve 70.

On the other hand, the reaction force control device 100 executes the program shown in FIG. 6 and outputs a control signal to the pressure control valve 70. In other words, the constantly changing input signal detected by the steering angle sensor 105 at the same time as the start of driving is sent to the microprocessor 1.
The data is stored in the RAM 103 via 01.

Therefore, the microprocessor 101 of the reaction force control device 100
is the steering wheel steering angle θ stored in the RAM 103 in step 200 at the same time as the start of the control program.
is read and stored in the buffer register. Following this, in step 201, a fourth
A control current i is searched based on the control pattern data shown in the figure, and then in step 202, the searched control current i is output to the solenoid drive circuit 104, and this signal is applied to the solenoid 73 of the pressure control valve 70. . As described above, when the steering wheel steering angle θ is within the angular range of 1 θL < θ + θL, this control current i is set to the maximum value and approaches the steering end ±θE outside this angular range. It is set to gradually decrease as the

Therefore, when the steering wheel is steered within the angle range of −θ to +θL, the solenoid 7 of the pressure control valve 70
3, the maximum control current i is applied, and as a result, the movable spool 74 is displaced to the right, and a large amount of pressure fluid leaks through this pressure control valve 70. As a result, no hydraulic reaction force is generated in the reaction force chamber 56 of the reaction force mechanism, and the steering handle can be easily steered without any hydraulic reaction force.

However, when the steering wheel is steered beyond the range of -θ<+θL, the control current i applied to the solenoid 73 of the pressure control valve 70 gradually decreases, causing the movable spool 74 to be displaced to the left. However, leakage of pressure fluid from this pressure control valve 70 is restricted. As a result, a hydraulic reaction force corresponding to the control current i is generated in the reaction force chamber 56 of the reaction force mechanism, and a predetermined steering reaction force is applied to the steering shaft 23.

By applying a hydraulic reaction force to the steering shaft 23 and gradually restraining its rotation in this way, as shown in FIG. 5A, the steering pressure increases compared to characteristic B of the conventional power steering device. As the pump load increases gradually, engine troubles can be resolved without sudden changes in the load on the engine, and the maximum steering pressure can also be kept low. , the engine load can also be reduced.

Furthermore, by suppressing sudden changes in the steering pressure near the steering end ±θE, automatic vibration of the servo valve 30 is prevented from occurring, and the friction force by the plunger is further added to this, so that the servo valve can be operated more actively. 30 vibrations are suppressed,
It is also possible to prevent abnormal noises from occurring due to this vibration.

In the above embodiment, a portion of the pressure fluid supplied to the servo valve 30 is supplied to the first servo valve 30. Although the flow is divided by the second flow control valve 61, 65 and supplied to the reaction force chamber 56 to apply hydraulic reaction force, the method is not limited to this, and the method is not limited to this, and the pressure reducing valve method or hydraulic reaction force is applied. It is also possible to use a method such as providing a separate pump for this purpose.

<Effects of the Invention> As detailed above, the control device for the power steering device of the present invention is configured to gradually increase the hydraulic reaction force in the reaction force chamber of the reaction force mechanism near the steering end. Therefore, it is possible to prevent a sudden increase in steering pressure and the resulting sudden increase in pump load, which can solve the problem of unstable engine rotation and even engine stall. Furthermore, it has the advantage of being able to prevent vibration of the servo valve and the generation of abnormal noise associated with it.

[Brief explanation of drawings]

The drawings show embodiments of the present invention, and FIG. 1 is a sectional view of the power steering device of the present invention together with a control circuit diagram, and FIG.
The figure is an enlarged sectional view taken along the line nn of Fig. 1, Fig. 3 is a sectional view of the main part of the pressure control valve, Fig. 4 is a diagram showing changes in control current with respect to the steering wheel steering angle, and Fig. 5 is a diagram showing changes in the control current with respect to the steering wheel steering angle. FIG. 6 is a flowchart showing the control program. 21... Pinion shaft, 23... Input shaft, 30...
Servo valve, 56... reaction force chamber, 60... supply pump,
61... First flow control valve, 65... Second flow control valve, 70... Pressure control valve, 100... Reaction force control device, 105... Steering angle sensor.

Claims (1)

[Claims] (1) In a power steering device equipped with a servo valve that is operated based on a manual steering torque applied to a steering handle and controls the supply of pressure oil to a power cylinder, and a reaction force mechanism that changes steering resistance, A steering angle sensor detects the steering angle of the steering wheel, and a reaction force control device controls the reaction force of the reaction force mechanism to increase near the steering end of the steering wheel based on a signal from the steering angle sensor. A control device for a power steering device characterized by: