JPS58209655A - Manual steering effort control device for power steering gear - Google Patents

Abstract

PURPOSE:To enlarge the range of controllability as well as to improve the responsiveness, by installing a solenoid valve controlling the discharge flow rate of a pump and also another solenoid valve interconnecting and controlling both end chambers of a power cylinder, while controlling each valve according to car speeds, wheel turning angles, etc. CONSTITUTION:A power steering gear 2 has a power cylinder 15 operated by a pressure fluid passing through a servo valve 14 being controlled by operation of a steering wheel 10 while the discharged fluid of a pump 16 is fed to the servo valve 14. In this case, a linear solenoid valve 20 bypass-controlling both end chambers of the power cylinder 15 according to car speed, etc., is installed. Also a linear solenoid valve 16 controlling the flow rate supplied to the servo valve 14 is installed in the pump 16 in addition. And each of solenoids 28 and 38 of these solenoid valves is controlled by a control circuit 54 with continuous rating current on the basis of the ouptut of each of detecting sensors 50-52 for car speeds and the turning angle and speed of the steering wheel.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a steering force control device for a power steering device, and in particular, a system for controlling steering force in accordance with vehicle speed, steering wheel rotation, angle, steering wheel rotation speed, etc.
This invention relates to a steering force control device that is electronically controlled.

In general, two methods are used to control steering force according to vehicle speed: one method is to reduce the discharge flow rate of the pump as the vehicle speed increases, and the other is to use a power steering system to control the constant flow of oil discharged from the pump as the vehicle speed increases. There are two main types of systems: bypass from the high pressure side to the low pressure side.

Conventionally, one of these two methods has been used as a vehicle speed responsive power steering system, but in cases where the control input conditions include the steering wheel rotation angle and steering wheel rotation speed in addition to the vehicle speed. However, there are problems in that it is not possible to obtain a sufficiently large control range using only one method as described above, and it is also difficult to perform appropriate control according to each control input condition.

Therefore, the purpose of the present invention is to expand the control range, improve responsiveness, and enable steering force control suitable for human characteristics and military strategy by combining the characteristics of the above two methods and performing electronic control. That's true.

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

In FIG. 1, the steering handle 10 is a steering wheel shaft 11.
A steering shaft 13 of a power steering device 12 is connected to the other end of the handle shaft 11 . The power steering device 12 includes a servo pulp 14 controlled by the manual steering torque transmitted to the steering shaft 13, and a power cylinder 15 to which pressure fluid is distributed by controlling the servo valve 14. The steering torque is transmitted to the steering wheels via a steering linkage (not shown). A pump 16 driven by the engine is provided to supply pressure fluid to the servo pulp 14 of the power steering device 12, and the discharge flow rate of this pump 16 is variably controlled by a flow rate control device to be described later. .

FIG. 2 shows a near solenoid valve 20 that bypass-controls both end chambers of the power cylinder 15 according to vehicle speed, etc. The spool 23 is slidably inserted into the inner hole 22 formed in the valve body 21. A bypass slit 24 is cut in this spool 23. The spool 23 is normally held at the lower end by the bias of the spring 25, and the passage 26 communicating with the left chamber of the power cylinder 11 and the passage 27 communicating with the right chamber are cut off from communicating with each other. When an attractive force is applied to the spool 23 according to the current value applied to the solenoid 28 and the spool 23 is displaced upwardly against the spring 25, both the nlJ passages 26 and 27 pass through the bypass slit 24. The steering force is changed according to the amount of displacement of the spool 23, that is, the current value applied to the two sides of the solenoid.

FIG. 3 shows a flow rate control device equipped with a linear solenoid valve 30 that controls the flow iX supplied to the nJ servo valve 14.
A spool 33 is slidably inserted into the spool 33, and a control hole 34 is formed in the spool 33. The control hole 34 has a variable throttle 36 between it and a passage 35 leading to the discharge area of the pump 16.
f: The passage 35 and the servo pulp 14 are communicated through the variable throttle 36. The spool 33 is normally held at the sliding end shown in the figure by the bias of the spring 37, and the opening area of the variable diaphragm 36 is maintained at the maximum. Accordingly, an attractive force is applied to the spool 33 in accordance with the current value applied to the solenoid 38, and when the spool 33 is displaced against the spring 37, the opening area of the +1■ variable diaphragm 36 is gradually reduced.

Reference numeral 39 denotes a bypass valve that bypasses the surplus flow of pressure fluid discharged from the pump 16 to the suction side, and this bypass valve 39 responds to the pressure difference before and after the variable restrictor 36.
Bypass passage 4 is designed so that this pressure difference is always maintained constant.
Control the opening area of 0. As a result, the flow rate supplied to the servo pulp 14 is reduced in accordance with the current value applied to the solenoid 3, and the steering force is changed.

FIG. 4 shows a control circuit that controls the two linear solenoids 28, 38, in which 50 is a vehicle speed sensor that detects the vehicle speed, 51 is a rotation angle sensor that detects the steering wheel rotation angle θ, and 52 is a rotation angle sensor. This is a differential circuit that differentiates the output of the sensor 51 and outputs a signal corresponding to the steering wheel rotation speed of 0, that is, a rotation angle sensor. These sensors 50.51
．． The analog output detected by 52 is input to a multiplexer 53, selected in a time-division manner, and input to a control circuit consisting of a microcomputer 54.

55 is a microcomputer 5 that performs digital calculation processing.
4 central processing unit (CPU
), 56 and 57 are its input and output parts, where the input part 56 converts the input signal from the multiplexer 53 into a digital value and sends it to the CPU 55, and the output part 57 receives a control signal from the CPU 55. is converted into an analog value and then sent to the amplifier 58. from the two output ports A and B.
59 to the two linear solenoids 28 and 38, respectively. Reference numeral 60 denotes a read-only memory C (hereinafter referred to as ROM) for storing a fixed program to be described later, and 61 denotes a random access memory capable of reading and writing (hereinafter referred to as RAM).

FIG. 5 is a graphical representation of the fixed program stored in the ROM 60, which consists of three types of characteristic maps I, I[, and III. Characteristic map I is used to bypass control both end chambers of the power cylinder 15 or to drive the solenoid of the near solenoid valve 20.
Characteristic maps (1) and (2) are used to control the flow rate supplied to the servo valve 14 and to drive the solenoid of the near solenoid valve 30.

The characteristic map I shows the solenoid 28 of the linear solenoid valve 20 depending on the vehicle speed ■ and the steering wheel rotation speed 0.
The current value applied to the vehicle is divided into
is programmed. This control current 11 is the vehicle speed ■
The higher the value, the larger the value, and the higher the handle rotation speed θ, the smaller the value. A predetermined rank area is designated according to the detected value of the steering wheel rotation speed θ, and a predetermined address within that rank area is designated according to the detected value of the vehicle speed ■, and the program is programmed to that address. It is possible to continuously output a control current of 1□.

The characteristic map ■ represents the current value 12 applied to the solenoid 38 of the linear solenoid valve 30 according to the steering wheel rotation angle θ and the vehicle speed ■, and the vehicle speed ■ is classified into multiple ranks (VM engineering N to VMAX). The control current 12 corresponding to the handle rotation angle θ is programmed for each rank. This control current 12 is determined by the steering wheel rotation angle θ
The larger the value is, the smaller the value is, and the higher the vehicle speed is, the larger the value is set. A predetermined rank area is designated according to the detected value of the vehicle speed ■, and a predetermined address S within that rank area is designated according to the detected value of the steering wheel rotation angle θ, and the program is programmed to that address. The control current 12 can be read out.

Furthermore, the characteristic map (■) represents the current value 13 applied to the solenoid 38 of the linear solenoid valve 30 according to the handle rotation speed θ. Rotational speed θ
The higher the value, the smaller the value is programmed.

Next, the control program will be explained based on FIG.

The ever-changing vehicle speed detected by each sensor 50, 51, and 52, the steering wheel rotation angle θ, and the steering wheel rotation speed O
Each control input is input to the input section 56 of the microcomputer 54 via the multiplexer 53, filtered, and stored in the RAM 61.

With the start of the program IJ, - the first step.

101, the 9 vehicle speed ■ is stored in the RAM 61.
, handle rotation angle O, and handle rotation speed O are read,
Shifted into buffer register. In the steering engine 102, the fixed program characteristic engine shown in FIG.

Control current 11 is searched from (2) and stored in memory. In step 103, the searched control current i
1 is output from the output capo A of the output section 57 and applied to the solenoid 28 of the linear solenoid pulp 2o.

Next, in step 104, a control current 12 is served from the characteristic map 1 based on the steering wheel rotation angle 0 and the vehicle speed 1, and is stored in the memory. Further step 1
At step 05, the control current i3 is searched from the characteristic map (2) based on the needle rotational speed of 0, and is stored in the memory. These control currents 12 and 13 are multiplied in step 106, and this multiplied value i4 is outputted from the output port B of the output section 57 (step lo'7) and applied to the solenoid 38 of the linear solenoid valve 30.

By controlling the current value 11+14 input to each solenoid 28.38 of the linear solenoid valve 20.30 in this way, the steering force can be adjusted to vehicle speed ■, steering wheel rotation angle θ,
It can be effectively controlled according to the handle rotation speed θ.

That is, during high-speed driving, the current value 1□ input to the solenoid 28 increases, and the current value 14 input to the solenoid 38 also increases, so that the discharge flow rate of the pump 16 is reduced, and at the same time, the power cylinder 15 The communication area between the chambers at both ends of the steering wheel becomes larger, which increases the steering force and provides high-speed stability.Furthermore, when driving straight, the discharge flow rate of the pump 16 is minimized, increasing stability when the steering wheel is in the neutral position. It will be done.

In addition, when turning off or suddenly steering the steering wheel, the current value 14 input to the solenoid 38 becomes small, causing the pump 1
Since the discharge flow rate of solenoid 28 is increased, the steering force becomes lighter, and the current value 11 input to the solenoid 28 also becomes smaller, especially when the steering wheel is turned suddenly, so that responsiveness is improved.

By controlling the two linear solenoid valves 20 and 30 in this manner, the control range can be expanded and fine control can be performed.

In the above embodiment, the solenoid valve 20 that controls communication between both end chambers of the power cylinder 15 is controlled mainly as a function of the vehicle speed, and the solenoid valve 30 that controls the discharge flow M of the pump 16 is controlled mainly based on the handle rotation angle and the handle rotation speed. I mentioned the example of controlling with the function of
A similar effect can be obtained by controlling the solenoid valve 20 as a function of the steering wheel rotation angle and the steering wheel rotation speed, or controlling the solenoid valve 30 as a function of the vehicle speed.

As described above, the present invention includes a solenoid valve that controls the discharge flow rate of a pump, and a solenoid valve that controls communication between both end chambers of a power cylinder, and each solenoid of these two solenoid valves is controlled to control vehicle speed, steering wheel rotation angle,
Since the configuration is electronically controlled according to the handle rotation speed, etc., the control range can be expanded compared to conventional ones, and the degree of freedom in control is increased, making it more accurate. It has the feature of being able to perform steering force control appropriate to the characteristics and military strategy of the aircraft.

[Brief explanation of the drawing]

The drawings show an embodiment of the present invention, and FIG. 1 is a diagram schematically showing a power steering device, FIG. 2 is a sectional view showing a near solenoid valve that controls communication between both end chambers of a power cylinder, and FIG. Figure 3 is a sectional view showing the near solenoid valve that controls the pump discharge flow rate, Figure 4 is a block diagram showing the solenoid control circuit, Figure 5 is a graphical representation of the control current program, and Figure 6. is a flowchart showing the control program. 10... Steering handle, 12. Power steering device, 1
+Le@*servo valve, 15**e power cylinder,
16[Yes] Φ・Pump, 20.30・Solenoid valve, 2B, 38・Solenoid, 50.51.5
2...Sensor, 54...Control circuit (microcomputer). Patent applicant Toyota Machinery Co., Ltd. Taku 1 Figure 2. Fig. 2 2゜ Fig. 5 (I) (II) (III) Rotation angle θ
1987-209
655 (6)

Claims (2)

[Claims] (1) A power steering device comprising a servo valve operated based on manual steering torque applied to a steering handle, a power cylinder whose supply and discharge of pressure fluid is controlled by the operation of this servo valve, and this power steering device. a pump that supplies pressurized fluid to the pump; a solenoid valve that controls the discharge flow rate of the pump according to the current value applied to the solenoid; and a solenoid valve that controls the discharge flow rate of the pump according to the current value applied to the solenoid; A second solenoid valve that communicates and controls the chamber, and a control current that is input to each solenoid of the first and second solenoid valves according to control human power conditions such as vehicle speed, steering wheel rotation angle, and steering wheel rotation speed. A steering force control device for a power steering device comprising a circuit. (2) A control current that is mainly a function of the vehicle speed is input to one solenoid of the first and second solenoid valves, and a control current that is mainly a function of the steering wheel rotation angle and steering wheel rotation speed is input to the other solenoid. A steering force control device for a power steering device according to claim 1, wherein a current is inputted to the steering force control device.