JPH036548Y2 - - Google Patents

Description

[Detailed Description of the Invention] (Industrial Field of Application) The present invention relates to a rear wheel steering regulating device in a front and rear wheel steered vehicle capable of steering the rear wheels of the vehicle in conjunction with the steering operation of the front wheels.

(Prior art) Conventional front and rear wheel steering vehicles are roughly divided into vehicles equipped with a mechanical rear wheel steering mechanism and vehicles equipped with an electrohydraulic rear wheel steering mechanism. It is equipped with a drive mechanism that moves a tie rod connected to the rear wheels via a knuckle arm left and right, and a control mechanism that controls this drive mechanism according to the steering state of the front wheels.

By the way, in order to improve maneuverability and stability in this type of vehicle, the steering angle (steering angle ratio) of the rear wheels relative to the front wheels is controlled to be in opposite phase at low vehicle speeds and gradually to be in phase as the vehicle speed increases. This is proposed, for example, in Japanese Patent Application Laid-open No. 11173/1983. However,
If such a control method is adopted, it is generally possible to improve the maneuverability and stability of the vehicle, but if the vehicle is turning at high speed and decelerates due to finding an obstacle, etc., the steering angle of the front wheels will remain constant. Despite the fact that the steering angle of the rear wheels is maintained at the same angle, the steering angle of the rear wheels is gradually turned to the opposite phase side as the vehicle speed decreases. There is a risk that a tuck-in phenomenon similar to the tuck-in phenomenon may occur.

(Purpose of the invention) The present invention was made to solve this problem, and its main purpose is to maintain a constant rear wheel steering angle or rear wheel steering angle ratio when decelerating and turning in this type of vehicle. The purpose is to solve the above problem.

(Structure of the invention) In order to achieve the above object, the present invention provides a vehicle of this kind in which the steering angle ratio control action of the control mechanism is interrupted and the drive mechanism is controlled so that the steering angle or steering angle ratio of the rear wheels is constant. The structure is characterized in that it is provided with a second control mechanism that controls the brake pedal so that the brake pedal is held at the brake pedal, and that the second control mechanism is operated in conjunction with depression of the brake pedal.

(Operations and Effects of the Invention) As a result, in the present invention, when the vehicle decelerates by depressing the brake pedal during a high-speed turn, the second control mechanism that operates in conjunction with the brake pedal decelerates the control mechanism (the first control mechanism). ), and the drive mechanism is controlled so that the steering angle or steering angle ratio of the rear wheels is maintained constant. Therefore, the steering angle or steering angle ratio of the rear wheels is kept constant despite the deceleration of the vehicle speed, and the rear wheels are not gradually steered to the opposite phase side. Therefore, according to the present invention, there is no risk of the vehicle being caught in the inside of the turn during a deceleration turn, so that maneuverability and stability can be further improved.

(Example) Hereinafter, the present invention will be described based on the drawings. FIG. 1 shows a schematic configuration of a vehicle equipped with an electro-hydraulic rear wheel steering mechanism to which the present invention is applied.

In such a vehicle, the rear wheels 11 are steered in conjunction with the front wheels 12, and each rear wheel 11 is connected to each tie rod 14 via a knuckle arm 13. Further, each tie rod 14 is connected at its inner end to a hydraulic actuator 20a of a rear wheel steering mechanism 20, which will be described later.

The rear wheel steering mechanism 20 is a hydraulic actuator 20a.
, a hydraulic drive device 20b that drives this, and an electric control device 20c that controls this. The hydraulic actuator 20a and the hydraulic drive device 20b constitute the drive mechanism of the present invention, and the hydraulic actuator 20a is connected to the cylinder 21.
and a piston rod 22 that fluidly and slidably penetrates both ends of the cylinder 21 and has a piston that divides the interior into left and right oil chambers.The inner end of each tie rod 14 is attached to the outer end of the piston rod 22. Both oil chambers of the cylinder 21 are connected to the servo valve 23 of the hydraulic drive device 20b. The hydraulic drive device 20b includes a servo valve 23 and a hydraulic pump 24 driven by an engine, and supplies hydraulic oil from the hydraulic pump 24 to the servo valve 23.
The switching operation functions to supply hydraulic oil to one oil chamber of the cylinder 21 of the hydraulic actuator 20a and to discharge hydraulic oil from the other oil chamber. As a result, the piston rod 22 of the hydraulic actuator 20a is moved left and right to steer the rear wheel 11. In such a hydraulic drive device 20b, the servo valve 23 is controlled by an electric control device 20c.

The electric control device 20c is a known device that corresponds to the first control mechanism of the present invention, and includes a vehicle speed sensor 25a, a front wheel steering angle sensor 25b, a command circuit 26, a servo amplifier 27, and a potentiometer for detecting the displacement of the piston rod 22. yon meter 28. This electric control device 20c includes a vehicle speed sensor 25a and a front wheel steering angle sensor 25.
The rear wheel steering angle δr is determined by the command circuit 26 based on the values of the vehicle speed V and the front wheel steering angle δf from b, and this value is sent to the servo amplifier 27. The servo amplifier 27 switches the servo valve 23 to control supply and discharge of hydraulic oil to and from the cylinder 21 of the hydraulic actuator 20a, and controls the rear wheel 11 to the steering angle δr determined by the command circuit 26. In addition, potentiometer 28
detects the displacement of the piston rod 22 and feeds it back to the servo amplifier 27, thereby performing feedback control. In this embodiment, the rear wheel steering angle δr is controlled as shown in FIG. 2 based on the relationship between the front wheel steering angle δf and the vehicle speed V.

In Figure 2, the ratio k of the rear wheel steering angle to the front wheel steering angle is
(δr/δf) decreases as the vehicle speed increases, which means that the steering angle δr of the rear wheels 11 is in the opposite phase to the steering angle δf of the front wheels 12 at low vehicle speeds, and This means that control is gradually performed toward the in-phase side as V increases. As a result, in the vehicle, the sideslip angle when turning is reduced, the direction of travel can be accurately predicted, and at low speeds, maneuverability and stability can be improved.

However, in the first embodiment of the present invention, the third
As shown in the figure, a steering regulation device 30 is provided. The steering regulation device 30 has the second control mechanism of the present invention as a main part, and the changeover switch 31 constituting the control mechanism is connected to the electric control device 2 of the vehicle.
Command circuit 26 and servo amplifier 27 forming 0c
It is interposed between. This changeover switch 31
is switched by energizing the electromagnetic coil 32, and this electromagnetic coil 32 is operated by the brake pedal 15.
When the switch 33 is closed by pressing the button, the switch 33 is energized. As a result, the changeover switch 31 is operated in response to the depression of the brake pedal 15, and when the changeover switch 31 is connected to the contact 31a side, the steering angle ratio control action of the electric control device 20c is interrupted, and the hydraulic actuator 20b servo valve 2
3 to return to the neutral position. Furthermore, when the depression of the brake pedal 15 is released, the changeover switch 31 is operated and connected to the contact 31b side, thereby restoring the steering angle ratio control action of the electric control device 20c.

In a vehicle configured in this manner, when the brake pedal 15 is released, the rear wheels 11 follow the curve shown in FIG. The vehicle is steered to the (-k) side. By the way, when the brake pedal 15 is depressed while the vehicle is turning at high speed, the changeover switch 31 is operated to switch the contact point 31a.
side, the steering angle ratio control action of the electric control device 20c is interrupted, and the servo valve 23 of the hydraulic drive device 20b is returned to the neutral position. As a result, the piston rod 22 of the hydraulic actuator 20a is locked, and the steering angle of the rear wheel 11 is maintained constant. For this reason, during deceleration turning, the rear wheels 11 gradually move out of phase (+
Since the vehicle is not steered to the k) side, there is no risk of the vehicle being rolled into the inside of the turn.

FIG. 4 shows a vehicle according to a second embodiment of the present invention. The vehicle is equipped with a mechanical-electro-hydraulic combined rear wheel steering mechanism, and in this vehicle, the knuckle arm 13 on one side of the front and rear wheels 12, 11 serves as the link device 4 of the rear wheel steering mechanism 40, which will be described later.
0a, a hydraulic drive device 40b that drives the lever mechanism, and an electric control device 40c that controls this. In such an embodiment, the linkage device 40a and the hydraulic drive device 40b
constitutes the drive mechanism of the present invention, and the electric control device 40c constitutes the first control mechanism. The link device 40a is composed of a pair of front and rear connecting rods 41a, 41b connected to the front and rear knuckle arms 13, a lever mechanism 42 to which the ends of these connecting rods 41a, 41b are pivotally connected, and a hydraulic actuator 43. . The lever mechanism 42 is a known one, and as shown in FIG.
a and 41b, and a movable fulcrum 42c that connects the guide rail 42a and the swing lever 42b to each other and is connected to the piston rod 43a of the hydraulic actuator 43 and moves along the guide rail 42a. Consisting of As a result, in this link device 40a, the front wheel 1
2 is steered, the connecting rod 41a moves back and forth, causing the swinging lever 42b to swing around the movable fulcrum 42c, causing the connecting rod 41b to move back and forth. As a result, the rear wheels 11 are steered in response to the steering operation of the front wheels 12, and the steering angle ratio k with respect to the front wheels is set at the movable fulcrum 4.
It is determined by a variable lever ratio at position 2c.

The hydraulic drive device 40b is composed of a servo valve 44 and a hydraulic pump 45, similar to the hydraulic drive device 20b in the first embodiment, and the switching operation of the servo valve 44 operates the hydraulic actuator 43 to move the movable fulcrum of the lever mechanism 42. to change the lever ratio of both connecting rods 41a, 41b. Also,
The electric control device 40c corresponds to the electric control device 20c in the first embodiment without the front wheel steering angle sensor 25b, and is composed of a vehicle speed sensor 46, a command circuit 47, a servo amplifier 48, and a potentiometer 49. has been done. This results in
The electric control device 40c controls the servo valve 44 according to the vehicle speed.
is controlled to change the movable fulcrum 42c of the lever mechanism 42. Also in this embodiment, the steering angle ratio k of the rear wheels 11 to the front wheels 12 is controlled as shown in FIG.

In this second embodiment as well, a changeover switch 31 constituting a second control mechanism is interposed between a command circuit 47 and a servo amplifier 48 constituting an electric control device 40c. This changeover switch 31 is operated by energizing the electromagnetic coil 32, and as a result, when the steering angle ratio control of the electric control device 40c is interrupted, the front and rear wheel steering angle ratio k can be kept constant. They function similarly and produce similar effects.

(Modified example) In each of the above embodiments, examples were shown in which the hydraulic actuators 20a, 43 and the hydraulic drive devices 20b, 40b were adopted.
For example, if the movable fulcrum 42c in the second embodiment is configured to be moved by an electric motor or the like, a hydraulic actuator, hydraulic drive device, etc. can be omitted.

[Brief explanation of the drawing]

Fig. 1 is a schematic configuration diagram showing an example of a vehicle to which the present invention is applied, Fig. 2 is a graph showing the steering state of the rear wheels in the same vehicle, and Fig. 3 is a vehicle according to the first embodiment of the present invention. FIG. 4 is a schematic configuration diagram of a vehicle according to a second embodiment of the present invention, and FIG. 5 is an enlarged perspective view of a lever mechanism in the same vehicle. Explanation of symbols, 11...Rear wheel, 12...Front wheel, 1
3...Natsukuru arm, 14...Tie rod, 2
0, 40...Rear wheel steering mechanism, 20a...Hydraulic actuator, 40a...Link device, 20b, 4
0b...hydraulic drive device, 20c, 40c...electric control device, 30...steering regulation device, 31...changeover switch.

Claims (1)

[Scope of utility model registration request] A drive mechanism for moving left and right tie rods connected to a pair of left and right rear wheels via knuckle arms; In a vehicle with front and rear wheel steering, which controls the front and rear wheels so that they gradually become in-phase as the steering angle increases, the steering angle ratio control action of the control mechanism is interrupted, and the drive mechanism is controlled to control the steering angle of the rear wheels or the steering angle of the rear wheels. A second control mechanism is provided to control the ratio to be kept constant,
A rear wheel steering restriction device in a front and rear wheel steered vehicle, characterized in that the second control mechanism is operated in conjunction with depression of a brake pedal.