JPS596171A - Controller for rear-wheel steering mechanism - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a control device for a rear wheel steering mechanism in a vehicle equipped with a front and rear wheel steering mechanism.

Conventional vehicle steering mechanisms are usually installed only on the front or rear wheels to steer only one of the front wheels or rear wheels, but recently, for special vehicles, the front wheel side A control device for a rear wheel steering mechanism has been developed that improves turning performance during low-speed driving by automatically interlocking the rear wheels in conjunction with the steering of the vehicle so that the rear wheels are steered in the opposite direction to the front wheels. There is.

However, in the control device for the rear wheel steering mechanism, the rear wheels are simultaneously steered in different directions regardless of whether the steering angle of the front wheels is large or small. When driving, it is necessary to disable the above-mentioned control, and if the vehicle is driven with the control in the activated state, the change in driving direction becomes unnecessarily large due to the addition of interlocking steering of the rear wheels, which impairs steering stability. be.

The present invention was developed to solve the above-mentioned difficulties in conventional rear wheel steering mechanism control devices, and includes a detector for detecting the turning direction and actual steering angle of the front wheels, and a detector for detecting the turning direction and actual steering angle of the front wheels. A control mechanism that issues a control signal when the actual steering angle of the front wheels reaches a set angle or more based on a detection signal, and a hydraulic cylinder of the rear wheel steering mechanism that is operated via a servo pulp or a switching valve controlled by the control signal. and the rear wheel steering mechanism that steers the rear wheels in a direction opposite to the actual steering direction of the front wheels when the actual steering angle of the front wheels reaches a set angle or more due to the operation of the hydraulic cylinder. death,
The purpose of this is that during normal driving with a small front wheel steering angle, the rear wheels are not steered in conjunction, but when driving at low speeds and the front wheel steering angle is increased, the rear wheels are steered in conjunction, improving steering stability and turning performance. The present invention provides a control device for an enhanced rear wheel steering mechanism.

The present invention has the above-described configuration, and controls the servo valve or switching valve on the rear wheel side by a control signal from the control mechanism issued when the actual steering angle of the front wheels reaches a set angle or more. The hydraulic cylinder of the rear wheel steering mechanism is actuated by a servo pulp or a switching valve, and when the actual steering angle of the front wheels reaches a set angle or more, the hydraulic cylinder causes the rear wheels to be steered in the opposite direction to the actual steering direction of the front wheels. Since it has a rear wheel steering mechanism, during normal driving when the actual steering angle of the front wheels does not reach the set angle, that is, the actual steering angle is small, the same steering stability as normal when the rear wheels are not steered in conjunction can be obtained, providing exceptional steering stability. To provide steering safety suitable for each driving condition in both high-speed and low-speed driving without requiring any operation, and to turn with the actual steering angle of the front wheels at a set angle or more during low-speed driving. In this case, the rear wheels are steered in a direction opposite to that of the front wheels, making it possible to make tight turns and significantly improve turning performance.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.

A first embodiment of the present invention is shown in FIGS.
In the figure, (1) is the front wheel steering handle, (2) is the detector that detects the turning direction and actual steering angle of the front wheels, and (3) is the detector (
2) is a control mechanism that inputs the detection signal and issues a control signal C when the actual steering angle of the front wheels reaches a set angle or more; (4) is a servo pulp controlled by the control signal C; (5) is:
The hydraulic cylinder (6) of the rear wheel steering mechanism (9) is actuated by the servo pulp (4) to steer the rear wheels, and (6) is an oil pump that supplies working pressure to the hydraulic cylinder (5). 6) and an oil tank connected to the servo pulp (4), and (8) a displacement detector that detects the displacement of the hydraulic cylinder (5).

Further, the control mechanism (3) inputs the detection signal of the detector (2), that is, the actual steering angle signal A including the turning direction of the front wheels, and generates a target steering angle signal B of the rear wheels based on a preset relationship. A control signal C proportional to the target steering angle signal B is output, and the servo valve (4) is controlled by the control signal C. The target steering angle D1 of the rear wheels is set by operating the hydraulic cylinder (5).
At the same time, the displacement of the hydraulic cylinder (5) is detected by the displacement detector (8) and a displacement signal is output, and the actual rear wheel steering angle setting device (3□) is used to detect the displacement signal. The actual steering angle signal D' of the rear wheels is calculated from a known relationship determined by the steering linkage, etc., and the target steering angle signal B and the actual steering angle signal D' are compared by a comparison correction setting device (33). At the same time, the control signal setter (34) is configured to provide a modified control signal C that matches the target steering angle signal B with the actual steering angle of the rear wheels.

Further, in the control device, the control relationship of the steering angle D10 of the rear wheels with respect to the actual steering angle A1 of the front wheels based on the control signal C is set as shown in FIG. That is, as shown in the figure, when the actual steering angle A1 of the front wheels is 0 or within the range of the set angle ±θ1, the target steering angle signal B from the rear wheel target steering angle setting device (3) is not generated. The control signal C is not output and the rear wheels are not steered in conjunction with each other. Also, the actual steering angle A1 of the front wheels is the set angle ±
When θ1 is reached, the target steering angle signal B is issued, that is, the control signal C
is output, and the servo valve (4) controlled by the control signal C operates the hydraulic cylinder (5) to adjust the steering angle D1 of the rear wheels, that is, the actual steering angle, as shown in the figure. Automatically interlock steering.

When the actual steering angle A1 of the front wheels reaches the set angle ±θ1 or more, the steering angle D1 of the rear wheels becomes opposite to the actual steering direction of the front wheels, and depending on the performance of the servo pulp (4), the steering angle D1 of the rear wheels becomes opposite to the actual steering direction of the front wheels. The actual steering angle gradually increases between ±01 and ±θ2, and thereafter is kept at a constant angle α.

Furthermore, as shown in Fig. 4, if a three-position switching valve (10) is provided in place of the servo pulp (4) shown in Fig. 1.2, the resulting steering angle D1 of the rear wheels is as shown in Fig. 5. As shown in , the range of gradual increase in the steering angle is almost eliminated and the steering angle is kept at a constant angle α.

The first embodiment shown in FIGS. 1 to 5 has the above-described structure, so that the actual steering angle A□ of the front wheels is the set angle ±θ.
During normal steering driving where the actual steering angle does not reach 1, that is, the actual steering angle is small, the same steering stability as normal driving where the rear wheels are not steered in conjunction can be obtained, and when the actual steering angle of the front wheels is greater than the set angle when driving at low speeds. That is, when turning with a large actual steering angle A1, the rear wheels are simultaneously automatically steered in a direction opposite to the front wheels, the turning radius of curvature is significantly reduced, and the turning performance is significantly improved. In other words, the optimal steering stability for each driving condition and high turning performance during low-speed driving can be obtained in both high-speed and low-speed driving without requiring special operations.

Further, according to this embodiment, since the target steering angle signal B is corrected based on the displacement signal obtained by detecting the displacement of the hydraulic cylinder (5) of the rear wheel steering mechanism (9), the corrected control signal C is used to control the rear wheel. Coupled steering can be made more accurate.

Next, FIG. 6 shows a second embodiment of the present invention. As is clear from FIG. 1.2 of the first embodiment, this second embodiment uses a vehicle speedometer (2E) in addition to the actual steering angle signal of the front wheels.
) is input to the target steering angle setter (3□') of the control mechanism (3), and the control signal C is output in proportion to the target steering angle signal B'3 generated from it. Furthermore, the steering angle D1 of the rear wheels according to the control signal C is equal to the actual steering angle A of the front wheels as shown in FIG.
When □ reaches ±θ1, the steering angle D1 of the rear wheels becomes automatic steering in the opposite direction to the actual steering direction of the front wheels, and the vehicle speed changes to Q - + E.
As the vehicle speed increases from E4 to E6, the rear wheel steering angle D1 becomes smaller, and as the vehicle speed increases further from E4 to E6, the rear wheel steering angle D1 is automatically steered in the same direction as the actual steering direction of the front wheels. It is designed to be The rest of the structure is substantially the same as that of the first embodiment shown in FIG. 1.2.

Therefore, according to the second embodiment shown in FIG. 6.7, in addition to basically having the effects of the first embodiment, the steering angle of the rear wheels is adjusted according to the degree of low speed when traveling at low speed. It has the advantage that D1 changes and the degree of turning corresponds to the speed and is made smooth. In addition, if the actual steering angle A1 of the front wheels is increased when the vehicle speed increases, the rear wheels are steered slightly in the same direction as the actual steering direction of the front wheels. It has the advantage of improving stability.

In addition, in the second embodiment, instead of the servo valve (4), a three-position switching valve (10) (see Fig. 4) is used, and the set angle ±θ1 is changed at high speed Q −
As +E becomes 3, it increases ±θ2. It is also possible to change the opening 1 signal C to ±θ3, and the characteristics in this case will be as shown in Fig. 8 [Compared to Fig. 7, the gradual increase in the steering angle of the rear wheels is virtually eliminated, and the vehicle speed increases. In response to this, the setting angle has also been increased, making it possible to more appropriately regulate the interlocking steering range of the rear wheels.

Furthermore, the sixth embodiment is shown in Fig. 9 and @Fig.
Compared to the second embodiment, this embodiment is characterized in that the rear wheel weight signal F detected by the weight meter (2F) is input to the control mechanism (3) and output as the control signal C. In addition to the front wheel actual steering angle signal A and the vehicle speed signal E, the rear wheel weight signal F is added to the control signal.
Actual steering angle A1 of the front wheels using vehicle speed signal E as a parameter
The relationship between the steering angle D1 and the steering angle D1 of the rear wheels is determined, and the control characteristics are shown in Figure 10 and are basically similar to those in Figure 7. At higher vehicle speeds, the steering angle of the rear wheels is set slightly larger than when the weight of the rear wheels is light, to avoid deterioration of stability due to increased weight.

On the other hand, the steering angle D1 of the rear wheels relative to the actual steering angle A1 of the front wheels when the vehicle speed is E1 to E2 increases with the increase of the person 1 at the actual steering angle A1 of the front wheels of −θ, ~θ, or more. θi
Above E0, the rear wheel steering angle is set to a constant value α1. regardless of the front wheel steering angle A1. I have to. That is, when the weight shared by the rear wheels changes, control is performed by changing θ, E, and α for each vehicle speed.

1. Other functions and effects are basically the same as those of the second embodiment. In addition, in FIG. 10, the solid line and the dotted line represent the characteristics when the weight shared by the rear wheels is large and small.

Furthermore, a fourth embodiment is shown in FIGS. 11 and 12, and in this @4 embodiment, the throttle opening signal T is further controlled by a control mechanism (3) compared to the second embodiment shown in FIG. The system is characterized by inputting the actual steering angle signal A of the front wheels and the vehicle speed signal E, as well as the throttle opening detector (2T) installed on the barrel or engine throttle.
) is input to the control mechanism (3) as a control element, and is calculated into a control signal C that immediately corrects the steering angle D1 of the rear wheels in the case of a sudden increase or decrease in the throttle opening T. It is now possible to do so.

In this case, the control is as follows: if there is no sudden increase or decrease in the throttle opening, that is, if there is no sudden operation of the accelerator,
A rear wheel target steering angle signal B is output from the actual steering angle A1 of the front wheels using the vehicle speed signal E as a parameter, a control signal C is output based on the signal B, and both the front and rear wheels are being steered. The target steering angle B of the rear wheels is immediately corrected when the throttle opening degree increases ΔT by more than a set value when the vehicle speed is higher than a certain value.

That is, for example, when the throttle (accelerator) is fully opened while turning at consecutive speeds E1 to E2 with the front wheel steering angle θ2 and the rear wheel steering angle α2 shown in FIG. 12, the front wheel steering angle θ2 remains constant. Even if the steering angle remains unchanged, the control is modified so that the rear wheel steering angle decreases from α2 to α2' (47 points) to make tuck-in less likely to occur.Conversely, if the accelerator is depressed during the same turn, For △T, the rear wheel steering angle D1 is slightly increased α2-α2
'It can also prevent the vehicle from drifting out.

At lower speeds (0-El), this throttle opening signal T
It is not necessary to control the steering angle of the rear wheels by the above-described method, and the control is performed only when the throttle opening increases or decreases by a certain value (ΔT) or more.

Specifically, tuck-in occurs in the direction where the turning radius becomes smaller when the accelerator is suddenly released during a turn, and tuck-in occurs in the direction where the turning radius becomes larger when the accelerator is suddenly depressed. This can be prevented by correcting the rear wheel target steering angle signal B using the throttle opening signal T.

Furthermore, the effects of the embodiment shown in FIG. 6 can be achieved in substantially the same manner in the fourth embodiment. In addition, also in the embodiment, a switching valve can be used instead of the servo valve.

[Brief explanation of the drawing]

Fig. 1 is an overall mechanism layout diagram of the first embodiment of the present invention, Fig. 2 is a control mechanism diagram of the first embodiment, Fig. 6 is a control characteristic diagram of the first embodiment, and Fig. 4 is a diagram of the control mechanism of the first embodiment. Modified diagram of the embodiment,
Fig. 5 is a control characteristic diagram of the modification shown in Fig. 4, Fig. 6 is a control mechanism diagram of the second embodiment, Fig. 7 is a control characteristic diagram of the second embodiment, and Fig. 8 is a control characteristic diagram of the second embodiment. Other control characteristic diagrams,
Fig. 9 is a control mechanism diagram of the sixth embodiment, Fig. 10 is a control 1 characteristic diagram in the @6 embodiment, Fig. 11 is a control mechanism diagram of the fourth embodiment, and Fig. 12 is a control mechanism diagram in the fourth embodiment. ! It is a characteristic diagram.゛2: Detector (front wheel actual steering angle), 2E 2 vehicle speed detector, 2F
: Rear wheel weight-M detector, 2T: Throttle opening detector, 3
= control mechanism, 4: servo valve, 5: hydraulic cylinder,
8: Displacement detector, 9: Rear wheel steering mechanism, 10: Switching valve, A
: Actual steering angle signal (front wheel), B: Target steering angle signal, C: Control signal, D = Displacement signal (rear wheel side) Sub-agent Patent attorney Shige Okamoto 2 people outside of the text Figure 1, Figure 2, Figure 3 Figure 4, Figure 5, Figure 6, 7 sides ■ Figure 8

Claims (1)

[Claims] A detector that detects the turning direction and actual steering angle of the front wheels, a control mechanism that issues a control signal when the actual steering angle of the front wheels reaches a set angle or more based on the detection signal of the detector, and a control mechanism that is controlled by the control signal. When the actual steering angle of the front wheels reaches a set angle or more due to the hydraulic cylinder of the rear wheel steering mechanism operated through the servo pulp or switching valve, etc. A control device for a rear wheel steering mechanism, characterized in that the control device includes the aforementioned rear wheel steering mechanism for steering a rear wheel.