JPH0230913B2 - - Google Patents

Description

Detailed Description of the Invention [Industrial Application Field] The present invention is applicable to vehicles in which the rear wheels are steered in addition to the front wheels, particularly four-wheeled vehicles such as passenger cars and commercial vehicles that run at low and high speeds. By steering the front wheels, steering the rear wheels in conjunction with the steering of the front wheels, and controlling changes in the steering ratio between the front wheels and the rear wheels according to the vehicle speed, responsiveness at high speeds can be improved.
Stability is further improved, and at low speeds, the rear wheels are kept unsteered regardless of whether the front wheels are steered, allowing you to comfortably perform low-speed driving operations such as parking, pulling over, and starting from parking. The present invention relates to a vehicle front and rear wheel steering device that allows easy steering.

[Prior Art] In a four-wheeled vehicle, it has been proposed to steer not only the front wheels but also the rear wheels. For example, the special public relations system in the 1970s
Publication No. 10728 discloses that in an automobile steered by a front wheel steering device, a steering angle is generated in the rear wheels by the moment of a caster rail caused by the cornering force of the rear wheels when the vehicle body turns by front wheel steering. The method has been disclosed.

The specific method is to once steer the rear wheels in the opposite direction to the direction in which the front wheels are being steered, using the moment of the caster rail caused by the cornering force generated in the rear wheels when the front wheels are steered in conjunction with the steering wheel operation. , use that force to move the spool valve,
It steers the rear wheels in the same direction as the front wheels.

Further, Japanese Patent Application Laid-Open No. 52-61024 discloses a method in which the rear wheels are steered in a phase opposite to the front wheels when the vehicle is running at low speeds, and only the front wheels are steered without steering the rear wheels when the vehicle is running at high speeds.

However, the technology disclosed in Japanese Patent Publication No. 40-10728 not only has technical problems such as accuracy in the detection method or sensor for detecting the side slip angle that controls the steering of the rear wheels, but also has technical problems such as accuracy due to the steering of the front wheels. This method corrects the steering of the rear wheels based on the indirect control factor that is used, that is, the control is performed after the vehicle direction changes due to the steering of the front wheels, so there is a delay in response to steering. I end up.

In other words, the rear wheels are steered only when a sideslip angle occurs, and the rear wheels are steered by the moment acting on the vehicle body, regardless of whether the vehicle is running at low speed or high speed.

Furthermore, since the rear wheel steering control depends on the μ between the road surface and the tires, the rear wheels will not be steered on a low μ road.

Furthermore, the technology disclosed in Japanese Patent Application Laid-Open No. 52-61024 focuses only on maneuverability of the vehicle when running at low speeds, and the same phase steering of the rear wheels makes steering easy and stable when running at high speeds. cannot improve sexuality.

In order to solve the above conventional problems, the present applicant previously proposed in Japanese Patent Application No. 53-163678 that the steering of the front and rear wheels is linked to the steering of the front wheels by steering wheel operation, and the steering of the front and rear wheels is adjusted according to the vehicle speed. We proposed a new front and rear wheel steering system that changes the steering ratio of the vehicle and steers the front and rear wheels in opposite phases when the vehicle is running at low speeds, and steers the front and rear wheels in the same phase when the vehicle is running at high speeds. .

According to this, the front wheel steering is linked to the rear wheel steering, and the steering ratio of the front and rear wheels is changed according to the vehicle speed, so that rear wheel steering with excellent responsiveness can be performed, especially when responsiveness is required. It is possible to significantly improve the response to steering when the front and rear wheels are steered in the same phase at high speeds, and to improve the ease and stability of steering the front and rear wheels at high speeds when the front and rear wheels are steered in the same phase. Can be done.

Since the rear wheel steering is controlled based on the vehicle speed, the front and rear wheels can be reliably steered even on low μ roads where accurate lateral force cannot be detected.

[Problems to be Solved by the Invention] By the way, in the proposed patent application No. 53-163678, reverse phase steering of the front and rear wheels is performed in the low vehicle speed region, so that parking in a garage or pulling to the side at low speeds is not possible. , it is also conceivable that driving operations such as starting from a parked vehicle may become intuitively difficult.

As an example, if the vehicle 200 is parked close to the wall-like road edge 201 as shown in FIG. , chain line 226'
Since the rear wheels 226 are steered in the opposite direction to the front wheels 217 as shown in FIG.
It is conceivable that the object may move to the 01 side and come into contact with it.

Similarly, in the technology disclosed in JP-A-52-61024, the rear wheels are steered in the opposite phase to the front wheels when driving at low speeds, making driving operations such as parking, pulling over, and starting from parking easier. You can't get sex.

Therefore, the object of the present invention is to
Among the functions and effects of the front and rear wheel steering device proposed in No.
In particular, while securing the advantage in the high vehicle speed range, the rear wheel steering operation is not performed in the low vehicle speed range, making driving operations performed at low speeds when parking, pulling over, or starting from parking feel unnatural. To provide a front and rear wheel steering device for a vehicle that can be easily operated without any trouble.

[Means for Solving the Problems] In order to achieve the above-mentioned problems, the present invention provides front wheel turning amount and steering direction detection means for detecting the turning amount and steering direction of the front wheels in conjunction with steering wheel operation. , a front wheel steering device that steers the front wheels based on a signal from the detection device, a vehicle speed detection device that detects the vehicle speed, a rear wheel steering device that steers the rear wheels, and a vehicle speed from the vehicle speed detection device. a rear wheel steering control device that sets the rear wheels to be steered within the same phase range as the front wheels based on a signal; A steering angle function generator that sets a steering ratio between front wheels and rear wheels based on a steering direction signal and a rear wheel steering setting signal from the rear wheel steering control device, and determines a steering amount of the rear wheels. When the vehicle speed is in a low vehicle speed region, by stopping the output of the rear wheel steering setting signal to the steering angle function generator, the steering ratio is set to zero and the rear wheel steering ratio is set to zero regardless of the steering state. The present invention is characterized in that the front and rear wheel steering devices of the vehicle are configured to control rear wheel steering while keeping the wheels in a non-steering state.

[Operation] When the front wheels are steered by operating the steering wheel, based on the front wheel steering status signal, the steering ratio of the rear wheels to the front wheels is determined according to the vehicle speed at that time, and in high vehicle speed ranges, the steering ratio of the rear wheels is linked to the steering of the front wheels. When the vehicle speed is in a low vehicle speed region, the output of the rear wheel steering setting signal to the steering angle function generator is stopped, and the rear wheels are steered in the same phase as the front wheels. The steering ratio is set to zero.

In other words, the present invention changes the steering ratio of the front and rear wheels according to the vehicle speed while linking the steering of the front wheels with the steering of the front wheels by steering wheel operation, and steers the front and rear wheels in the same phase when the vehicle is running at high speed. In addition, when the vehicle speed is in a low vehicle speed region, the output of the rear wheel steering operation signal to the steering angle function generator is stopped regardless of the front wheel steering state, and the rear wheels are kept in a non-steering state. It is something.

First, when steering at high speeds, the front and rear wheels are steered in the same phase while changing the steering ratio based on the vehicle speed while linking front and rear wheel steering.
Even immediately after starting steering, the rear wheels generate cornering force at the same time as the front wheels, and the vehicle's lateral acceleration reaches the intended value in an extremely short period of time, greatly improving responsiveness to steering. In other words, there is no time delay between turning the steering wheel and changing the direction of the vehicle, making it easier and more stable to operate.

As a result of the above, it is possible to perform high-speed in-phase steering of the front and rear wheels that follows the vehicle speed with good responsiveness, and even on low μ roads where accurate lateral force cannot be detected or when external forces such as crosswinds are applied, it is possible to perform high-speed in-phase steering that follows the vehicle speed. It is possible to reliably perform front and rear wheel steering using the same phase.

When the vehicle speed is in a low speed range, the output of the rear wheel steering setting signal to the steering angle function generator is stopped regardless of the front wheel steering state, so that the rear wheels are kept in a non-steering state, and the rear wheels are not steered. .

Therefore, when performing low-speed driving operations such as parking the vehicle in a garage, pulling over to the side, or starting from a parked vehicle, the driving operation can be performed by steering only the front wheels as in the conventional case.

[Example] Examples will be described below based on the accompanying drawings.

FIG. 1 shows a first embodiment of the front and rear wheel steering system of the present invention, and only the left front and rear wheels of a four-wheeled vehicle are shown, but the right wheel, which is not shown in the figure, is a tie rod. It is designed to be steered in conjunction with the left wheel by known means such as.

In FIG. 1, the rotational movement of the handle 10 causes the gearbox 1 to face the pinion of the steering shaft 10a.
The gearbox 11 is converted into a reciprocating movement of the rack within the gearbox 11, and an arm rod 12 that moves linearly rearward extends out from the gearbox 11. The rear part of the arm rod 12 is inserted into the differential gear 13, and a pinion 14 is rotatably supported at the rear end of the arm rod 12.

The differential gear 13 has a pair of left and right racks 13a, 1.
3b is installed inside the racks so as to be individually slidable back and forth, and the pinion 14 is interposed between the two racks 13a and 13.
It meshes with b.

The left rack 13a is a connecting rod 15 that extends forward.
is connected to the front wheel support member 16 via the rack 1.
Point 16 of the front wheel support member 16 due to the back and forth movement of 3a
The front wheels 17 are steered by swinging back and forth about a. In this way, the mechanism of the gearbox 11 is connected to the rack 13 of the differential gear 13 via the arm rod 12.
A, 13b and a pinion 14 form a front wheel turning amount and turning direction detection means, and a rack 13a is connected to a connecting rod 15 of the front wheel steering device.

The rack 13a is connected to the left end of the moving arm 19 via a connecting rod 18 extending rearward, and the moving arm 19, which has a length in the left-right direction, can swing back and forth about a movable fulcrum 20.

On the other hand, an arm rod 21 disposed at the rear is connected to the right rack 13b via a lever rod 22, and the rack 13b and the arm rod are connected by the load transmission reversal action of the lever rod 22, which has a rotation center at a point 22a. 21, the load transmission direction is reversed. The arm rod 21, which has a backward length, is connected to the movable arm 1 at a point 23 halfway in the length direction.
9, and its pivot point 23 is farther to the right than the pivot point 24 between the connecting rod 18 and the movable arm 19.
In this way, a steering angle function generating device is formed by the movable arm 19 having the movable fulcrum 20 and the pivoting portion 23, and the pivoting portion 23 is connected to the rear half of the arm rod 21 of the rear wheel steering device. . A connecting rod 1 is connected between the movable arm 19 and the front wheel turning amount and steering direction detecting means.
8. The lever rod 22 and the front half of the arm rod 21 are interposed. The rear end of the arm rod 21 is connected to a rear wheel support member 25, and the rear wheel 26 is steered by swinging the rear wheel support member 25 back and forth about a point 25a as the arm rod 21 moves back and forth.

Reference numeral 30 denotes a vehicle speed detection means for detecting the running speed of the vehicle. A signal from the vehicle speed detection means 30 is input to a controller 31 such as a computer and processed, and the signal from the controller 31 is used to control the drive means 3 such as a motor.
2 is driven, and a screw rod 33 extending parallel to the movable arm 19 rotates.

A screw piece 34 having a movable fulcrum 20 is screwed into the screw rod 33, and under the control of a controller 31, a driving means 32 rotates the screw rod 33 in the normal direction.
The position of the movable fulcrum 20 on the movable arm 19 changes by reversing and stopping the rotation and moving the screw top 34 on the screw rod 33, and the movable fulcrum 20 moves to a position corresponding to the vehicle speed and stops. That is, a controller 31 receives a signal from a vehicle speed detection means 30, a drive means 32 receives a drive signal from the controller 31, a screw rod 33 is connected to the drive means 32, and the screw rod 33 is movable by rotation. The screw top 34 constitutes a rear wheel steering control device. A screw top 34 on the screw rod 33 makes the movable fulcrum 20 of the movable arm 19 of the steering angle function generator variable.

As the vehicle speed increases, the movable fulcrum 20 moves away from the pivot 23, that is, to the right in the figure,
If the vehicle speed decreases, it moves to the left. The limit position of the leftward movement of the movable fulcrum 20 is the pivot joint 23, and it will not move leftward any further, and the movement range of the movable fulcrum 20 is the area between the pivot joint 23 and the right end of the movable arm 19. It is.

The movable fulcrum 20 remains at the position of the pivot joint 23 when the vehicle speed is in a low vehicle speed region below a predetermined value, and the predetermined speed is 40 km/h or 20 km/h.
It is desirable to set it to h.

The above-mentioned position change and position setting of the movable fulcrum 20 are performed by a controller 31 that receives a vehicle speed signal detected by a vehicle speed detection means 30.

That is, when the vehicle speed is equal to or higher than a predetermined value, a rear wheel steering setting signal from the rear wheel steering control device is input to the steering angle function generator to set the steering ratio between the front wheels and the rear wheels. The rear wheels are steered within the same phase range depending on the steering state of the wheels.

When the vehicle speed is in a low vehicle speed region below a predetermined value, the output of the rear wheel steering setting signal from the rear wheel steering control device is stopped, and the steering ratio setting of the steering angle function generator becomes zero. Regardless of the front wheel steered state, the rear wheels are controlled to be in a non-steered state.

Since the front and rear wheel steering device according to the present invention has the above configuration, when the handlebar 10 is rotated to the right in FIG.
A back-pressing force is applied to the left and right racks 13a and 13b from this point. The rear pushing force acting on the left rack 13a is transmitted from the pivot portion 24 to the movable arm 19 and becomes a moment that tends to swing the movable arm 19 backward around the movable fulcrum 20, while on the other hand, it acts on the right rack 13b. The rear pushing force is transmitted from the pivot portion 23 to the movable arm 19 and becomes a moment that attempts to move the movable arm 19 forward around the movable fulcrum 20. The magnitude of these moments differs depending on the distance between the movable fulcrum 20 and the pivot joint 24 and the distance between the movable fulcrum 20 and the pivot joint 23, and as a result, the movable arm 19 swings backward. . As a result, within the differential device 13,
The left rack 13a moves backward, and the right rack 13a moves backward.
b moves forward, and this differential movement of both racks 13a, 13b is effected by the rotation of pinion 14.

The front wheels 17 are steered to the right by the differential movement of the differential device 13 and the rocking movement of the moving arm 19, and the rear wheels 26 are also steered to the right, in the same direction as the steering direction of the steering wheel 10. The front and rear wheels are steered.

When the steering wheel 10 is rotated to the left, the above operation is simply reversed, and both the front and rear wheels are steered to the left.

The steering angle of the rear wheel 26 is determined by the movable fulcrum 20 on the movable arm 19.
The steering ratio of the rear wheels 26 to the front wheels 17 is determined by the distance between the movable fulcrum 20 and the pivot joint 24 and the distance between the movable fulcrum 20 and the pivot joint 23. As the position of the movable fulcrum 20 shifts to the right, in other words, as the vehicle speed increases beyond the predetermined speed, the steering angle of the rear wheels 26 increases, and the steering ratio of the rear wheels 26 to the front wheels 17 increases. is 1
approaches. As the vehicle speed decreases, this steering ratio decreases, but when the vehicle speed reaches a low vehicle speed region below the predetermined speed, the position of the movable fulcrum 20 matches the position of the pivot joint 23, and the vehicle stops at that position. . That is, the output of the rear wheel steering setting signal to the steering angle function generator is stopped, and the steering ratio becomes zero. Therefore, even if the steering wheel 10 is operated, only the front wheels 17 are steered, and the rear wheels 26 are not steered. Not steered.

In this way, the front and rear wheel steering system of the vehicle is controlled by the front wheel turning amount and steering direction detecting means which detects the turning amount and turning direction of the front wheels in conjunction with the steering wheel operation, and the signal from the front wheel turning direction. , a front wheel steering device that steers the front wheels, a vehicle speed detection device that detects vehicle speed, a rear wheel steering device that steers the rear wheels, and a vehicle speed signal from the vehicle speed detection device that steers the rear wheels. a rear wheel steering control device configured to steer the front wheels within the same phase range; a front wheel steering amount and steering direction signal from the front wheel steering amount and steering direction detection means; It consists of a steering angle function generator that sets the steering ratio between the front wheels and the rear wheels based on the rear wheel steering setting signal from the rudder control device, and determines the amount of steering of the rear wheels. In the region, by stopping the output of the rear wheel steering setting signal to the steering angle function generating device, the steering ratio is set to zero and the rear wheels are placed in a non-steered state regardless of the front wheel steered state; It is configured to control rear wheel steering.

Next, FIG. 2 shows a second embodiment, and although only the left wheel is shown in this figure, the relationship with the right wheel is exactly the same as described above.

In FIG. 2, the rotating operation of the handle 110 is converted into a linear movement of the arm rod 112 within the gear box 111, causing the front wheel support member 116 connected to the rear end of the arm rod 112 to swing back and forth about a point 116a. Also, the connecting rod 118 is moved back and forth. In this way, the mechanism of the gearbox 111 and the arm rod 112
A front wheel turning amount and steering direction detecting means is formed, and an arm rod 112 is connected to a front wheel support member 116 of the front wheel steering device.

The rear end of the connecting rod 118 is pivotally connected to the left end of a movable arm 119 that can swing back and forth at a movable fulcrum 120, and at a position shifted to the right from this pivot portion 124, the movable arm 119 and the arm rod are connected. Pivot joint 123 with 121
is provided, and the rear wheel support member 125 connected to the arm rod 121 moves to the point 12 as the arm rod 121 moves back and forth.
It swings back and forth around 5a.

The movable fulcrum 120 is provided on the screw piece 134,
The screw piece 134 is a screw rod 1 that can be rotated forward, reversed, and stopped by a drive means 132 such as a motor.
33, and the driving means 132 is connected to the vehicle speed detecting means 1.
Its driving is controlled by a controller 131 which receives signals from 30.

As described above, the movable fulcrum 120 and the pivot joint 123
A steering angle function generator is formed from the movable arm 119 having a controller 131 and a drive means 132.
A rear wheel steering control device is formed from the screw rod 133 and the screw top 134. A pivot portion 123 of the movable arm 119 forming the steering angle function generator is connected to the arm rod 121 of the rear wheel steering device, and between the movable arm 119 and the front wheel turning amount and steering direction detecting means. A connecting rod 118 is interposed. A screw top 134 on the screw rod 133 makes the movable fulcrum 120 of the movable arm 119 of the steering angle function generator variable.

With the above configuration, the movable fulcrum 120 moves in the area between the pivot joint 123 and the right end of the moving arm 119, and as the vehicle speed increases beyond the predetermined speed, the movable fulcrum 120 moves between the pivot joint 123 and the right end of the moving arm 119. The movable fulcrum 120 moves away from the pivot point 12 in a low vehicle speed region where the vehicle speed is below the predetermined speed.
This is the same as in the first embodiment.

When the vehicle speed exceeds the predetermined speed, when the handle 110 is rotated, the moving arm 119 is caused to swing back and forth about the movable fulcrum 120 from the arm rod 112 and the connecting rod 118, and the rear wheel 126 moves forward and backward relative to the front wheel 11.
7, the wheels are steered in the same direction as the front wheels. The steering ratio of the rear wheels 126 to the front wheels 117 changes depending on the position of the movable fulcrum 120, that is, the vehicle speed, and when the vehicle speed falls into a low vehicle speed region below the predetermined speed, the steering ratio becomes zero.

The advantages of the front and rear wheel steering devices of the present invention based on the above embodiments will be described with reference to FIGS. 3 and 4.

Figure 3 shows the case of starting from parking.
When the vehicle 200 is parked close to the wall-shaped road edge 201 and attempts to start by steering the front wheels 217 using the steering wheel, the steering ratio is zero, the rear wheels 226 are not steered, and the vehicle 200 is driven straight. Because the vehicle is in the correct position, you can start off without any problems.

That is, the rear wheel 226 is connected to the front wheel 2 as shown by the chain line 226'.
17, the vehicle 20
The rear part of the vehicle 0 can be moved toward the wall-like road edge 201 and can be prevented from coming into contact with it.

Furthermore, in the present invention, in a high vehicle speed range exceeding the predetermined speed, the rear wheels are steered together with the front wheels, which causes yawing around the center of gravity of the vehicle, unlike in the past when only the front wheels are steered when the vehicle turns. Cornering force can be generated simultaneously in the front and rear wheels, eliminating time delay and improving responsiveness. Furthermore, as shown in FIG. 4, the direction A of the vehicle when turning and the tangent C of the turning locus B can be made to coincide, or at least approximately coincide, so that driving becomes easier. Note that D and E indicate the directions of movement of the front wheels 217 and rear wheels 226 during turning.

[Effects of the Invention] As described above, according to the present invention, the front and rear wheels can be steered in the same phase when the vehicle is running at high speed by linking the front wheel steering with the rear wheel steering by steering wheel operation. The front and rear wheel steering system controls the steering ratio of the front and rear wheels in a manner that is variable depending on the vehicle speed while linking front and rear wheel steering. It is possible to obtain ease and stability, and eliminate the delay in response of rear wheel steering due to the related control factor, which was a problem with conventional devices, by correcting the rear wheel steering by following the generated lateral force etc. This can be achieved by steering the front and rear wheels in the same phase while changing the steering ratio in conjunction with front wheel steering based on the vehicle speed, which can be easily detected.

Therefore, it is possible to perform rear wheel steering with excellent steering response without any time delay from when the steering wheel is operated until the direction of the vehicle body changes.In other words, it is possible to perform high-speed in-phase steering of the front and rear wheels that follows the vehicle speed with high responsiveness. This can be done well, and it can greatly improve the response to steering when the front and rear wheels are steered in the same phase at high speeds where responsiveness is required, and the front and rear wheels are steered in the same phase. The ease and stability of front and rear wheel steering at high speeds can be improved.

Furthermore, even on low-μ roads where accurate lateral force cannot be detected or when external forces such as crosswinds are applied, the front and rear wheels can be reliably steered in the same phase at high speeds.

When the vehicle speed is in a low speed range, the output of the rear wheel steering setting signal to the steering angle function generator is stopped regardless of the front wheel steering state, so that the rear wheels are kept in a non-steering state, and the rear wheels are not steered. .

Therefore, when performing low-speed driving operations such as parking the vehicle in a garage, pulling over to the side, or starting from a parked vehicle, the driving operation can be performed by steering only the front wheels as in the conventional case.

[Brief explanation of drawings]

FIG. 1 is a schematic plan view showing a first embodiment of the front and rear wheel steering device of the present invention, FIG. 2 is a schematic plan view showing the second embodiment, and FIG. 3 is a plan view showing the case of starting from parking. , FIG. 4 is a plan view showing when the vehicle is turning. In addition, in the drawing, 10, 110 are handles, 11,
111 is the gearbox, 12 and 112 are the armrests, 1
7,117 is the front wheel, 19,119 is the moving arm, 20,
120 is a movable fulcrum, 26, 126 is a rear wheel, 30,
130 is a vehicle speed detection means, 31 and 131 are controllers,
32 and 132 are drive means, 33 and 133 are screw rods, and 34 and 134 are screw pieces.

Claims (1)

[Scope of Claims] 1. Front wheel turning amount and steering direction detection means for detecting the amount and direction of turning of the front wheels in conjunction with steering wheel operation; and a signal from the detection means to steer the front wheels. a front wheel steering device that steers the vehicle speed; a vehicle speed detection device that detects vehicle speed; a rear wheel steering device that steers the rear wheels; a rear wheel steering control device configured to steer within a phase range; and a front wheel steering amount and steering direction signal from the front wheel steering amount and steering direction detection means and a front wheel steering amount and steering direction signal from the rear wheel steering control device. a steering angle function generator that sets the steering ratio between the front wheels and the rear wheels based on the rear wheel steering setting signal and determines the amount of steering of the rear wheels; By stopping the output of the rear wheel steering setting signal to the angle function generator, the steering ratio is set to zero, and the rear wheels are controlled to be in a non-steered state regardless of the front wheel steered state. A front and rear wheel steering device for a vehicle, characterized by: