JP2902090B2 - Vehicle steering system - Google Patents

Description

Description: BACKGROUND OF THE INVENTION The present invention relates to a steering apparatus for a vehicle, and more particularly to a steering apparatus for steering a front wheel and a rear wheel. And to enable the rear wheels to return to neutral even if a failure occurs in the electric system during rear wheel steering.

(Prior Art) A steering device of a vehicle has, for example, a configuration as shown in FIG. First, the front wheels 1, 1 and the rear wheels 3, 3 are arranged. Knuckle arms 5, 5 having different shapes are connected to the front wheels 1, 1, and both knuckle arms 5, 5 are connected via a link 7.

In addition, an integral power steering (hereinafter referred to as IPS) 9 is installed.
11 includes a knuckle arm 5 connected to one of the front wheels 1.
Are connected via a link 13.

The steering wheel 15 is installed and this steering wheel
Reference numeral 15 is connected to the IPS 9 via a universal joint 2. The switching valve 17 of the IPS 9 has the operating positions 17a and 17b and the neutral position.
It has 17c. When the steering handle 15 is rotated in an appropriate direction, the switching valve 17 is switched to an arbitrary position, and the pressure oil supplied from the hydraulic pump 19 is supplied to the IPS9.
To the piston upper and lower chambers (working oil chambers) from appropriate directions.
Discharge. The hydraulic pump 19 suctions and pressurizes oil in the tank 21 and is driven by the engine 23.

The rear wheels 3, 3 have knuckle arms 2 of different shapes.
The knuckle arms 25 are connected via tie rods 27, respectively.
A rear wheel steering cylinder mechanism 29 is provided between the knuckle arms 25,25. This rear wheel steering cylinder mechanism 29
Is composed of a right cylinder 31 and a left cylinder 33.

Also, a hydraulic pump 35 as a hydraulic pressure source is installed,
The hydraulic pump 35 is driven by the above-described engine 23. The hydraulic pump 35 sucks and pressurizes oil in a tank 37, and supplies the rear wheel steering cylinder mechanism via an electromagnetic servo valve 39.
Supply and discharge to 29.

The electromagnetic servo valve 39 has operating positions 39a and 39b and a neutral position 39c, and is operated by the controller 41. That is, the turning operation of the steering wheel 15 is detected by the steering wheel angle sensor 43, and the controller 41 operates the electromagnetic servo valve 39 in an appropriate direction based on the detected operation. Thereby, the pressure oil from the hydraulic pump 35 is supplied and discharged to the rear wheel steering cylinder mechanism 29, and the rear wheels 3, 3 are steered in the opposite direction to the front wheels 1, 1.

An unload valve is provided between hydraulic circuits 45 and 47 provided from the hydraulic pump 35 to the rear wheel steering cylinder mechanism 29.
49 is inserted. The unload valve 49 communicates with the hydraulic circuits 45 and 47 to put the hydraulic pump 35 into a no-load state when the rear wheels 3 and 3 are not steered.

When the rear wheels 3 are to be steered, the rear wheel steering switch 51 is turned on. If the rear wheels 3, 3 are not to be steered, the rear wheel steering switch 51 is turned off, thereby locking the rear wheels 3, 3 by a rear wheel fixing device (not shown).

First, a description will be given of a so-called two-wheel steering for steering only the front wheels 1 and 1 based on the above configuration. In this case,
The rear wheel steering switch 51 is turned off, and the rear wheels 3, 3 are locked by the rear wheel fixing device. In this case, the hydraulic circuits 45 and 47 are in communication with each other by the unload valve 49.

First, when the steering handle 15 is rotated in an arbitrary direction, the switching valve 17 is switched to an appropriate position, whereby
The hydraulic oil is supplied and discharged from the hydraulic pump 19 to the IPS 9 in an appropriate direction, and through the piston arm 11, the link 13, the knuckle arm 5, the link 7, and the knuckle arm 5, the front wheels 1, 1
Is steered in any direction. The switching valve 17
Is returned to the neutral position 17c, and the steering is completed.

Next, so-called four-wheel steering for steering the front wheels 1 and 1 and the rear wheels 3 and 3 will be described. In this case, the rear wheel steering switch 51 is turned on. As a result, the lock of the rear wheels 3, 3 by the rear wheel fixing device is released, and the unload valve 49 is closed to shut off the hydraulic circuits 45, 47.

When the steering wheel 15 is rotated in an appropriate direction, the front wheels 1 and 1 are steered by the operation described above. The rotation of the steering wheel 15 is controlled by a steering angle sensor.
The detected signal is input to the controller 41.

The controller 41 operates the electromagnetic servo valve 39 in an appropriate direction based on various conditions input in advance. Thereby, the pressure oil from the hydraulic pump 35 is supplied and discharged to the rear wheel steering cylinder mechanism 29 via the electromagnetic servo valve 39. That is, the right cylinder 3 of the rear wheel steering cylinder 29
1. Pressure oil is supplied to one of the left cylinders 33, and the other pressure oil is returned to the tank 37.

Thereby, the rear wheels 3, 3 are steered by a predetermined amount in the same or opposite phase as the front wheels 1, 1. The turning state of the rear wheels 3, 3 is detected by a rear wheel steering angle sensor 53, and the detection signal is input to the controller 41. When a predetermined amount of steering is completed based on the detection signal, the controller 41 moves the electromagnetic servo valve 39 to the neutral position 39.
Return to c. When the electromagnetic servo valve 39 returns to the neutral position 39c, the right cylinder 31 of the rear wheel steering cylinder mechanism 29,
The oil passage of the left cylinder 33 is shut off, and the state is maintained.

(Problem to be Solved by the Invention) According to the above-described conventional configuration, there are the following problems.

First, in order to control the output flow rate in the electromagnetic servo valve 39, it is necessary to always keep the hydraulic pressure supplied to the electromagnetic servo valve 39 constant. This is the same in the control standby state. Here, the control standby state means that the unload valve
This means a period from when the control 49 is closed to the actual control, or between the control and the next control.

Therefore, even during such control standby, it is necessary to apply a constant hydraulic pressure, which has caused a large loss.

In addition, the electromagnetic servo valve 39 has advantages such as being able to operate with a small input and being capable of providing various control patterns with good responsiveness. There is a problem that malfunction may be caused by dust or the like.

Further, if any failure occurs in the electric system during four-wheel steering, the right and left cylinders 31 and 33 of the rear wheel steering cylinder mechanism 29 are in a locked state. There is a problem that it cannot be returned to the position.

The present invention has been made based on such a point, and an object of the present invention is to realize a desired function without using an electromagnetic servo valve having various problems, and to realize a failure in an electric system. In such a case, it is an object of the present invention to provide a vehicle steering device capable of returning a rear wheel to a neutral position.

(Means for Solving the Problems) To achieve the above object, a vehicle steering apparatus according to the present invention includes a rear wheel steering cylinder mechanism including a right cylinder and a left cylinder arranged to correspond to a pair of rear wheels. A hydraulic source connected to the rear wheel steering cylinder mechanism via a pair of circuits for supplying and discharging pressure oil to the rear wheel steering cylinder mechanism, and a hydraulic source interposed between the rear wheel steering cylinder mechanism and the hydraulic source. A switching valve having an operating position for supplying / discharging pressure oil to the rear wheel steering cylinder mechanism from an appropriate direction and a neutral position for communicating the pair of circuits, a drive valve controlled by a controller, and a clutch. A switching valve driving means for appropriately switching the switching valve, a cylinder and a piston rod slidably housed in the cylinder, and connected to the switching valve. A valve sensing cylinder connected to the valve sensing cylinder and a piston rod disposed adjacent to one of the pair of rear wheels and slidably accommodated in the cylinder. The working fluid filled in the cylinder by being connected and turning the rear wheel is supplied to and discharged from the valve sensing cylinder from the appropriate direction through the pair of circuits to the valve sensing cylinder, and thus the switching valve. A steering angle sensing cylinder to be operated and switching means interposed between the valve sensing cylinder and the steering angle sensing cylinder for interrupting or communicating the pair of circuits are provided.

(Operation) At the time of four-wheel steering, first, the switching valve drive mechanism is driven by the controller, whereby the switching valve switches in an appropriate direction. By the switching operation of the switching valve, the pressure oil from the hydraulic pressure source is supplied and discharged to the rear wheel steering cylinder mechanism from an appropriate direction.

Thereby, the rear wheels are steered by a predetermined amount in an appropriate direction. The steering angle sensing cylinder operates with the turning of the rear wheel. That is, by turning the rear wheel, the cylinder of the steering angle sensing cylinder and the piston rod relatively move, and the working fluid filled in the cylinder is
Supply to the valve sensing cylinder via a pair of circuits
Discharge.

Thereby, the cylinder of the valve sensing cylinder and the piston rod move relatively, and the switching valve is returned to the neutral position. Thus, the steering of the rear wheels is completed.

Also, if the electrical system fails for any reason,
The operation of returning the rear wheel to the neutral position will be described. In this case, the switching means is operated to connect a pair of circuits provided between the steering angle sensing cylinder and the valve sensing cylinder.

As a result, the steering angle sensing cylinder and the valve sensing cylinder are both free, and the valve sensing cylinder is returned to the neutral position by the built-in elastic member for neutral return or by an external operation, whereby the switching valve is switched. I do. The operation of the switching valve returns the rear wheels to the neutral position.

(Embodiment) Hereinafter, a first embodiment of the present invention will be described with reference to FIG. 1 and FIG.

The same parts as those in the related art are denoted by the same reference numerals, and description thereof is omitted.

First, a switching valve 101 is inserted in the circuits 45 and 47. The switching valve 101 has operating positions 101a, 101b and a neutral position 101c, and when switching to the operating positions 101a, 101b, pressurized oil supplied from the hydraulic pump 35,
It supplies and discharges the rear wheel steering cylinder mechanism 29 from an appropriate direction. When the position is switched to the neutral position 101c, the hydraulic circuits 45 and 47 are communicated to bring the right cylinder 31 and the left cylinder 33 of the rear wheel steering cylinder mechanism 29 into the same pressure state. or,
The switching valve 101 includes a centering spring 102, as shown in FIG.

The switching valve 101 is driven by the switching valve driving means 103. First, the DC motor 105 is installed.
The C motor 105 is driven by the controller 41. A reducer 109 is connected to the DC motor 105 via a crutch 107, and the spool of the switching valve 101 is operated via the reducer 109. The moving position of the switching valve 101 with respect to the point O is detected by an input steering angle sensor 111 mechanically connected.

A steering angle sensing cylinder 113 is provided between the knuckle arm 25 of the rear wheel 3 and the axle 26. The steering angle sensing silling 113 includes a cylinder 115 and a piston rod 1 slidably housed in the cylinder 115.
17 and the piston 1 attached to this piston rod 117
19 and oil 1 as a working fluid filled in the cylinder 115
21. The cylinder 115 is connected to the axle 26, and the piston rod 117 is connected to the knuckle arm 25.

Then, when the rear wheels 3, 3 are steered, the piston rod 117 and the cylinder 115 move relatively to supply and discharge the oil 121 from an appropriate direction.

A valve sensing cylinder 123 is connected to the switching valve 101 described above. The valve sensing cylinder 123 includes a cylinder 125, a piston rod 127 slidably housed in the cylinder 125, a piston 129 attached to the piston rod 127, and a cylinder 12
5 is filled with an oil 131 as a working fluid.

The cylinder 125 is fixed to the vehicle body, and the piston rod 1
As shown in FIG. 2, 27 is connected to the casing of the switching valve 101 via conversion means 133 for converting linear motion into rotary motion. In the case of the present embodiment, the valve sensing cylinder 123 has a centering spring (not shown).

Further, the input steering angle sensor 111 described above may be mounted so as to detect the relative displacement between the cylinder 125 and the piston rod 127 in the valve sensing cylinder 123.

The steering angle sensing cylinder 113 and the valve sensing cylinder 123 are connected via circuits 135 and 137. A needle valve 139 as switching means is interposed between these two circuits 135 and 137. The needle valve 139 is normally closed at the time, so that the circuit 13
5, 137 are in a blocked state. On the other hand, if necessary, the valve is opened to connect the circuits 135 and 137. As a result, the steering angle sensing cylinder 113 and the valve sensing cylinder 123 are brought into a free state.

The ACC 141 is attached to the circuit 135. This ACC14
1 opens the needle 139 at the time of adjusting the device, the steering angle sensing cylinder 113, the valve sensing cylinder 123, the circuit 13
5. It compresses the air mixed in the 137 to ensure the volume transfer characteristics of the working fluid and also has the function of replenishing the working fluid against leakage to the outside.

The volume change of the ACC 141 in the operation of the steering angle sensing cylinder 113 and the valve sensing cylinder 123 is because the sensing cylinders 113 and 123 of the steering angle and the valve are for the purpose of position detection and are not for transmitting power. , Very few.

However, the control accuracy of the rear wheel steering angle position has a small effect. For this reason, when the control accuracy of the rear wheel steering angle position is particularly required, a needle valve (same as the needle valve 139) for shutting off the oil passage is provided between the ACC 141 and the circuit 135, or What is necessary is just to make ACC141 a desorption system and to carry out the operation | movement described above.

However, if air mixing and leakage can be prevented between the steering angle sensing cylinder 113 and the valve sensing cylinder 123, the ACC 141 is not necessarily required.

 The operation will be described based on the above configuration.

First, a case of two-wheel steering in which only the front wheels 1 and 1 are steered, but this is as described in the description of the conventional example, and a description thereof will be omitted.

Next, a case of four-wheel steering for steering the front wheels 1 and 1 and the rear wheels 3 and 3 will be described. First, the rear wheel steering switch 51 is turned on. Thereby, the lock of the rear wheels 3, 3 by the rear wheel fixing device is released.

When the steering handle 15 is rotated in an arbitrary direction, the switching valve 17 is switched to an appropriate direction, whereby the hydraulic pressure from the hydraulic pump 19 is supplied to and discharged from the IPS piston upper and lower chambers of the IPS 9 from an appropriate direction. . Thereby, the front wheels 1, 1 are steered via the piston arm 11, the link 13, the knuckle arm 5, the link 7, and the knuckle arm 5. At the same time, the switching valve 17 returns to the neutral position 17c, whereby the steering of the front wheels 1, 1 is completed.

The amount of rotation of the steering wheel 15 is determined by the steering angle sensor 43.
And the detection signal is input to the controller 41. Controller 41 is based on the DC motor
Rotate 105 in the appropriate direction. By the rotation of the DC motor 105, a switching valve is provided via a clutch 107 and a speed reducer 109.
101 is driven.

Then, the pressure oil from the hydraulic pump 35 is supplied to and discharged from the rear wheel steering cylinder mechanism 29 in an appropriate direction, whereby the rear wheels 3, 3 are rotated in the same or opposite phase as the front wheels 1, 1. Steered. Again, a signal is input from the input steering angle sensor 111 to the controller 41, and the controller 41 controls the DC motor 105 based on the signal to control the rear wheel 3,
3 is steered by the target value.

As the rear wheels 3 are steered, the steering angle sensing cylinder 113 is displaced in one direction. That is, cylinder 1
15 and the piston rod 117 are relatively displaced. As a result, the oil 121 is supplied to and discharged from the valve sensing cylinder 123 via the circuits 135 and 137.

As a result, the valve sensing cylinder 123 is displaced in one direction, the switching valve 101 is operated, and the neutral position 101c
To return to. By the return of the switching valve 101 to the neutral position 101c, the circuits 45 and 47 are connected to each other to be in a no-load state, and the steering of the rear wheels 3, 3 is completed.

In such a series of operations, some trouble may occur in the electric system while the rear wheels 3, 3 are being steered. In this case, it is necessary to return the rear wheels 3, 3 to the neutral position.

Therefore, first, the controller 41 is turned off. When the controller 41 is turned off, the clutch 107 is released, and the reduction gear 109 and the switching valve 101 can be operated even when the DC motor 105 is locked.

Next, the needle valve 139 is opened, and the circuits 135 and 137 are opened.
To make the steering angle sensing cylinder 113 and the valve sensing cylinder 123 free. When the valve sensing cylinder 123 enters the free state, the valve sensing cylinder 123 returns to the neutral position by the built-in centering spring, thereby operating the switching valve 101.

When the switching valve 101 operates, the pressure oil from the hydraulic pump 35 is supplied to and discharged from the rear wheel steering cylinder mechanism 29, whereby the rear wheels 3, 3 return to the neutral position. Switching valve
101 is thereafter returned to the neutral position 101c by the centering spring 102.

In this embodiment, the valve sensing cylinder is used.
Since the piston rod 127 of 123 has a rod protruding on both sides of the piston 129, by pressing the protruding portion with the needle valve 139 opened,
The valve sensing cylinder 123 may be returned to the neutral position. In this case, no centering spring is required.

As described above, according to the present embodiment, the following effects can be obtained.

First, instead of the electromagnetic servo valve, by using the switching valve 101 to communicate the circuits 45, 47 at the neutral position 101c, various problems that the electromagnetic servo valve had, namely, the problem of loss during control standby, The problem of high cost and the problem of malfunction due to dust can be solved.

Also, in the event that a failure occurs in the electric system during steering of the rear wheels 3, 3, the controller 41 is turned off and the needle valve 139 is opened to return the rear wheels 3, 3 to the neutral position. Can be done.

Further, since the steering angle sensing cylinder 113 and the valve sensing cylinder 123 are not for power transmission but for position detection and feedback, they may be small and lightweight, and do not induce an increase in the size of the device.
Another advantage is that the degree of freedom in mounting is high.

Next, a second embodiment will be described with reference to FIG. In the case of the first embodiment, the piston rod 117 of the steering angle sensing cylinder 113 has a rod projecting on both sides of the piston 119. May be used. Similarly, for the valve sensing cylinder 123, the piston rod 127
May be used that protrudes only on one side.
In this case, the valve sensing cylinder 123 needs centering springs 140 and 142.

Next, a third embodiment will be described with reference to FIG. In the case of this embodiment, the speed reducer 109 is constituted by gears 143 and 145, and the gear 145 is provided with a manual operation section 147. With this configuration, the rear wheels 3, 3 can be returned to the neutral position by rotating the manual operation section 147.

(Effects of the Invention) As described in detail above, according to the vehicle steering system of the present invention, it is possible to eliminate a loss during control standby and reduce costs during rear wheel steering. Further, even if a failure occurs in the electric system during rear wheel steering, the rear wheels can be returned to the neutral position.

[Brief description of the drawings]

1 and 2 are views showing a first embodiment of the present invention. FIG. 1 is a configuration diagram of a steering device, FIG. 2 is a diagram showing a part of FIG. 1 in detail, and FIG. FIG. 4 is a diagram showing a part of the steering device according to the second embodiment, FIG. 4 is a diagram showing a part of the steering device according to the third embodiment, and FIG. 5 is a configuration diagram of a conventional steering device. 1,1… Front wheel, 3,3… Rear wheel, 29… Rear wheel steering cylinder mechanism, 31
... right cylinder, 33 ... left cylinder, 35 ... hydraulic pump (hydraulic power source), 41 ... controller, 101 ... switching valve, 103
... switch valve driving means, 113 ... steering angle sensing cylinder, 123 ... valve sensing cylinder, 139 ... needle valve (switching means).

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-62-131875 (JP, A) JP-A-64-78977 (JP, A) JP-A-4-56685 (JP, A) JP-A-Heisei 4- 5170 (JP, A) JP-A-62-221973 (JP, A) JP-A 63-156868 (JP, U) JP-A 60-45266 (JP, U) JP-A 62-8878 (JP, U) (58) Field surveyed (Int.Cl. ⁶ , DB name) B62D 5/07 B62D 7/14

Claims (1)

(57) [Claims] 1. A rear wheel steering cylinder mechanism having a right cylinder and a left cylinder disposed to correspond to a pair of rear wheels, and a rear wheel steering connected to the rear wheel steering cylinder mechanism via a pair of circuits. A hydraulic source for supplying and discharging hydraulic oil to and from the cylinder mechanism, and an operating position interposed between the rear wheel steering cylinder mechanism and the hydraulic source for supplying and discharging hydraulic oil to the rear wheel steering cylinder mechanism from an appropriate direction A switching valve having a neutral position for communicating the pair of circuits; a switching valve driving means which is controlled by a controller and has a clutch for appropriately switching the switching valve; and a cylinder and a cylinder. A valve sensing cylinder comprising a piston rod slidably housed and connected to the switching valve; and a valve sensing cylinder adjacent to one of the pair of rear wheels. And a cylinder rod and a piston rod slidably housed in the cylinder, and connected to the valve sensing cylinder via a pair of circuits, and the rear wheel is steered to fill the cylinder. Between the steering angle sensing cylinder, which supplies and discharges fluid to the valve sensing cylinder from the appropriate direction through the pair of circuits to operate the valve sensing cylinder and thus the switching valve, and the valve sensing cylinder and the steering angle sensing cylinder Switching means interposed between the first and second circuits for interrupting or communicating the pair of circuits.