JPS61184173A - Steering force controller for power steering device - Google Patents

Abstract

PURPOSE:To obtain a fail-safe function by constructing a solenoid valve which controle the flow rate of the delivery of a pump and a solenoid valve which controls connection between both end chambers of a power cylinder in such a way that their controlled aribles vary with the same characteristics, in the captioned device having said solenoid valves. CONSTITUTION:A power steering device 10 makes feeding/discharging control of pressure fluid for a power cylinder 16 by rotating a steering handle 19 to make rotating control of a servo valve 14, thereby, transmitting steering torque which is increased by means of the power cylinder 15, to steering wheels. This power steering device 10 is fed with pressure fluid from an engine-driven pump 22. In this system, each of solenoid valves V1,V2 are constructed in such a way that, as a current applied to the first solenoid valve V1 which is attached to the pump 22 and controls the flow rate of its delivery and the solenoid valve V2 which is attached to the power cylinder 15 and controls connection between both of its end chambers, varies from zero to the maximum, the controlled variables of both of the solenoid valves V1,V2 can be varied with the same characteristics.

Description

[Detailed Description of the Invention] <Industrial Application Field> The present invention prevents the handle from becoming abnormally heavy or light when the control circuit that controls the solenoid valve operates abnormally, thereby always keeping the handle on the safe side. The present invention relates to a steering force control device for a power steering device to be controlled.

<Prior Art> A steering force control device of a conventional power steering device controls the discharge amount of the pump according to the current value applied to a solenoid in a path leading from the pump to the power cylinder via a servo valve. A first solenoid valve and a second solenoid valve that controls communication between both end chambers of the power cylinder according to the current value applied to the solenoid are inserted. The second electromagnetic valve is configured to be controlled by control signals corresponding to various input signals output from the control circuit.

For example, when the steering wheel is in the neutral position, the opening degree of the first solenoid valve is reduced to reduce the pump discharge flow rate, making the steering wheel operation heavier, and as the vehicle speed increases, the opening degree of the second solenoid valve is gradually increased. Increase the bypass flow rate? This makes it difficult to operate the steering wheel.

<Problems to be solved by the invention> However, in such conventional steering force control devices,
The characteristics of the first solenoid valve are set to such that the pump discharge flow rate decreases as the current applied to the solenoid increases, and the second
The characteristics of the solenoid valve are set so that the bypass flow rate increases as the current applied to the solenoid increases. For this reason, the first. If the control device that controls the second solenoid valve fails and the current applied to the solenoid of each solenoid valve becomes zero, the bypass flow rate decreases and at the same time the pump discharge flow rate increases, causing the handle to become extremely light. On the other hand, when the current applied to the solenoids of the two valves increases to its maximum value, the bypass flow rate increases and at the same time the pump discharge flow rate decreases, making the handle extremely heavy, giving the driver a sense of anxiety.

The present invention has been made in order to eliminate such problems in the conventional art. As the current applied to the solenoid of the second solenoid valve changes from zero to the maximum value, this first solenoid valve changes from zero to the maximum value. The first solenoid valve is configured such that the pump discharge amount and the bypass flow rate controlled by the second solenoid valve are both changed with the same characteristics. The present invention is characterized in that a second solenoid valve is configured.

<Operation> Since the present invention has the above configuration, when the control circuit fails and the current applied to both solenoids becomes zero,
When one of the bypass flow rate and pump discharge flow rate increases, the other increases at the same time, so the handle does not become extremely heavy, and even if the applied current to both solenoids increases to the maximum value due to a failure in the control circuit, When one of the bypass flow rate and the pump discharge flow rate decreases, the other also decreases, so it is possible to prevent the handle from becoming extremely light.

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

In Fig. 1, 10 is a power steering device, and servo valve 1
4 and a power cylinder 15. The servo valve 14 is connected to a steering handle 19 via a handle shaft 17, and the power cylinder 15 is connected to steering wheels via a steering linkage of the enclosure. Therefore, by applying manual steering torque to the steering handle 19 and controlling the rotation of the servo valve 14, the power cylinder 15
Pressure fluid is supplied and discharged under control, and the increased steering torque is transmitted to the steered wheels by the power cylinder 15.

A pump 22 is connected to the power steering device 10. This pump 22 is connected to the automobile engine via a belt drive system, and the pumping action of this pump 22 supplies pressurized fluid to the power steering device 10.

The pump 22 is provided with a flow control valve 40 and a first electromagnetic valve V1 shown in FIG. This flow control valve 4
0 is a throttle 45 that controls the pressure fluid flowing from the discharge hole 12 of the pump 22 to the delivery port 43, and a supply flow rate supplied to the servo valve 14 by sliding and opening and closing the bypass hole 44 by the back and forth pressure of this throttle 45. The spool valve member 46 controls the spool valve member 46.

The first solenoid valve ■1 has a solenoid 49 and a solenoid 4.
The valve shaft 51 includes a movable spool 50 that is displaced by energization to the movable spool 50, and a valve shaft 51 that is integrally connected to the movable spool 50 and adjusts the opening degree of the throttle 45. The movable spool 50 is normally pressed to the left in FIG. 2 together with the valve shaft 51 by a spring 53, so that the opening of the throttle 55 is fully closed. However, as a current value iA is applied to the solenoid 49 and the movable spool 50 is displaced to the right against the repulsive force of the spring 53, the valve shaft 51 approaches the throttle 45 and its opening degree decreases, thereby pumping the discharge fluid. The flow rate QA is controlled. The relationship between this current value iA and the pump discharge flow rate QA is as shown in FIG. 5. As the current value energized to the solenoid 49 increases, the flow rate supplied from the delivery port 43 to the servo valve 14 increases. .

Further, a second solenoid valve v2 shown in FIG. 3 is attached to the power cylinder 15. This second solenoid valve 2 controls the pump pressure of the pump 22 by bypassing a part of the pressure fluid supplied to one chamber of the power cylinder 15 to the other chamber of the power cylinder 15. The valve body 24 includes a main body 24, a spool 26 slidably inserted into an inner hole 25 of the valve main body 24, and a solenoid 27. The spool 26 is normally held at the lower end by the bias of the spring 28, and the passage 30 communicating with the left chamber of the power cylinder 15 and the passage 31 communicating with the right chamber are blocked from communicating with each other.

When an attractive force is applied to the spool 26 according to the current value iB energized to the solenoid 27, the spool 26
is displaced upwardly against the spring 28, and the passages 30, 31 are communicated with each other via a bypass slit 34. The relationship between this current value iB and the bypass flow rate QB is as shown in FIG.
The relationship is such that as the current value iB flowing through the slit 7 is increased, the bypass flow rate QB passing through the slit 34 is increased.

In FIG. 4, 54 is a control device. This control device 5
4 is a microprocessor 55, ROM 60, and RAM
61 as the main component, this microprocessor 5
5 includes an output section 57 and a solenoid drive circuit 58.5.
9 are connected, and the first. The current applied to the solenoids 49°27 of the second electromagnetic valves Vl and V2 is controlled. The microprocessor 55 also has an input section 56.
A steering angle sensor 69 and a vehicle speed sensor 74 are connected via.

On the other hand, the ROM 63 contains the first. second solenoid valve Vl,
A control pattern of the applied current applied to the V2 solenoid 49.27 is stored as a characteristic map. FIG. 7 shows this control pattern.

As shown in FIG. 8, characteristic maps A and B are prepared. Characteristic map A is used to drive the solenoid of solenoid valve ■1 that controls the flow rate supplied to servo valve 14, and characteristic map B is used for driving the solenoid of solenoid valve ■1 that controls the flow rate supplied to servo valve 14. It is used to drive the solenoid of the solenoid valve v2 that bypass-controls both end chambers of the valve 15.

In characteristic map A, the current value iAO is small when the steering wheel is in the neutral position, and the current value iA gradually increases as the steering wheel is steered.

Further, in characteristic map B, the current value iB is set to be small when the vehicle is running at low speeds, and to be large when the vehicle is running at high speeds.

Next, the control operation of the steering force control device will be explained.

Steering angle signal θ that changes moment by moment detected by steering angle sensor 69 and vehicle speed sensor 74 while the car is running.
The vehicle speed signal V detected at
61.

On the other hand, the microprocessor 61 executes processing operations based on the program at the same time as the interrupt signal is input. First of all,
The microprocessor 61 reads the steering angle signal θ and the vehicle speed signal V stored in the RAM 61, sets the current values iA and iB according to the input conditions at that time from the characteristic maps A and B, and based on these set values, the first. Second solenoid valve V1. Current is applied to solenoid 49.27 of V2.

This characteristic map A is set so that the current value iA is small when the steering wheel is in the neutral position, so when the steering wheel is in the neutral position, the opening degree of the first solenoid valve v1 is small, and as a result, the pump discharge flow rate is reduced, and the steering wheel is in the neutral position. becomes heavy.

In addition, characteristic map B shows the current value iB as the vehicle travels at high speed.
Since the opening of the second solenoid valve v2 increases when driving at high speeds, the bypass flow increases and the power cylinder is weakened, which makes the steering wheel heavier when driving at high speeds. Stability can be increased.

In this way, the first. Solenoid of the second solenoid valve 48.20,
The applied current for 49.27 is 55
The current values iA and iB are set according to the current steering wheel angle θ and the vehicle speed V according to the control signal from the controller, thereby controlling the steering force according to the running state of the vehicle.

However, the control device 5 including this microprocessor 55
4 is out of order, the above-mentioned 1. Although the current values iA and iB of the currents applied to the second solenoid valves Vl and V2 change to zero or the maximum value, in the present invention, the pump discharge in response to changes in the current values iA and iB to be applied to the solenoids 49.27 The characteristics of the flow rate QA and bypass flow rate QB are set to be the same for the first solenoid valve ■1 and the second solenoid valve ■2, so the handle will not become extremely heavy or light. .

That is, when the applied current to each solenoid 49.27 becomes zero, the opening degree of the first solenoid valve ■1 becomes the minimum and the pump discharge flow rate QA decreases, but at the same time, the opening degree of the second solenoid valve ■1 decreases. In order to reduce the bypass flow rate Qa by reducing the bypass flow rate Qa, the actions of both solenoid valves Vl and V2 complement each other to ensure a constant amount of flow rate supplied to the power cylinder 15, and as a result, the steering wheel becomes extremely It does not become heavy and is set at a moderate weight, so it does not make the driver feel anxious.

Further, when the applied current to each solenoid 49.27 rises to the maximum value, the opening degree of the first solenoid valve VlO becomes the maximum and the pump discharge flow rate QA rapidly increases, but at the same time, the opening degree of the second solenoid valve V2 increases. also reaches its maximum and the bypass flow rate QA increases, so that both solenoid valves Vl and V2 complement each other and the flow rate supplied to the power cylinder 15 does not increase abnormally (as a result, the handlebars do not move excessively). Since it prevents the vehicle from becoming too light and the weight is set at an appropriate level, there is no need to worry about giving the driver a sense of anxiety.

<Effects of the Invention> As described above, the present invention provides the above-mentioned first effect. As the current applied to the solenoid of the second solenoid valve changes from zero to the maximum value, this first solenoid valve changes from zero to the maximum value. The first solenoid valve is configured such that the pump discharge amount and the bypass flow rate controlled by the second solenoid valve are both changed with the same characteristics. Since the second solenoid valve is configured, even if the control circuit fails and the current applied to the solenoids of the first and second solenoid valves changes to zero or the maximum value, both solenoid valves will complement each other. It is possible to prevent the fluid supplied to the power cylinder from suddenly increasing or decreasing rapidly, and it has a so-called fail-safe function that always guides the handle to the safe side, and prevents the handle from becoming extremely heavy or light. It has the advantage of being able to prevent

In the above embodiment, the first electromagnetic valve V1 is configured so that the pump discharge flow rate Q^ increases as the applied current iA increases, and at the same time, the bypass flow rate QB increases as the applied current iB increases. The second solenoid valve V1 is configured to reduce the pump discharge flow rate QA in accordance with an increase in the applied current iA, and the first solenoid valve V1 is configured to reduce the pump discharge flow rate QA in accordance with an increase in the applied current iA, and is not limited to this. Even if the second solenoid valve v2 is configured to reduce the bypass flow IQs in accordance with the increase in the solenoid iB, it is possible to achieve the same effect as in the embodiment described above.

In the above embodiment, the first solenoid valve v1 that controls the flow rate supplied to the servo valve 14 is controlled by the steering angle signal θ, and the second solenoid valve v2 that bypass-controls both end chambers of the power cylinder 15 is controlled by the vehicle speed V. Although the control is not limited to this, the first solenoid valve v1 is controlled by the vehicle speed V,
The second electromagnetic valve V2 may be controlled by the steering angle θ.

[Brief explanation of drawings]

The drawings show an embodiment of the present invention, and FIG. 1 shows a power steering device, and FIG. 2 shows a second embodiment of the invention.
3 is a sectional view showing a second solenoid valve that controls communication between both end chambers of the power cylinder, FIG. 4 is a block diagram showing the control device, and FIGS. 5 and 6 are diagrams of the solenoid. Graphs showing changes in pump discharge flow rate and bypass flow rate with respect to applied current, FIGS. 7 and 8 are graphs graphically showing applied currents to the solenoids of the first and second solenoid valves. vl...first solenoid valve, v2...second solenoid valve, 14.
...Servo valve, 15...Power cylinder, 22.
... Pump, 54... Control device.

Claims (1)

[Claims] (1) A first electromagnetic valve that controls opening and closing according to the current value applied to a solenoid in an oil path leading from the pump to the power cylinder via a servo valve to control the discharge flow rate of the pump; a second valve that is controlled to open and close according to the current value and communicated with both end chambers of the power cylinder;
A steering force control device of a power steering device in which a solenoid valve is inserted and the first and second solenoid valves are controlled by a control signal from a control device is provided in the control device, and an application to the solenoids of the first and second solenoid valves is provided. The first and second solenoid valves are configured so that as the current changes from zero to a maximum value, the pump discharge amount and the bypass flow rate controlled by the first and second solenoid valves both change with the same characteristics. A steering force control device for a power steering device, characterized in that: