JP2734043B2 - Actuator runaway prevention device - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a runaway prevention device such as an actuator that steers rear wheels of a four-wheel steering vehicle.

[Related Art] In a vehicle in which a rear wheel steering angle is controlled by a hydraulic or pneumatic actuator, it is impossible to completely suppress a small change in the rear wheel steering angle due to road surface input, and therefore, the rear wheels travel straight at high speed. To ensure stability, a neutral locking mechanism is provided to mechanically secure the actuator to a neutral position. However, if pressure oil is supplied to the actuator while the neutral locking mechanism is in the locked state, not only is excessive force applied to the actuator and the neutral locking mechanism, but also the rear wheels are not steered as desired.

For this reason, it is necessary to operate and release the neutral locking mechanism in synchronization with the start of the actuation of the actuator from the neutral position, and if this synchronous operation is electrically controlled, the control device becomes complicated. Further, when a hydraulic pressure failure occurs during the steering of the rear wheel, it is required that the rear wheel is prevented from being further steered by an external force (do not run away) and is gradually returned to the straight traveling position.

[Problems to be Solved by the Invention] In view of the above-described problems, an object of the present invention is to have a simple structure, in which the neutral locking mechanism is released simultaneously with the activation of the actuator from the neutral position, and when the hydraulic pressure is lost, the actuator is subjected to an external force. It is an object of the present invention to provide a runaway prevention device for an actuator which moves only to a neutral position in response to a runaway.

Means for Solving the Problems In order to achieve the above object, the present invention has a configuration in which a pair of piston rods are inserted into a cylinder to define a pair of end chambers, and a pair of piston rods are connected to opposite ends thereof. 1 to extend radially outward from both ends of the cylinder.
A pair of locking rods parallel to the piston rod are slidably supported on the pair of protruding walls so as to be able to abut on the abutment, and the cam and the inner surface of the protruding wall can be abutted on the inner end of the locking rod. And a release actuator for connecting a pair of links between the pair of rocking rod joints and bending the pair of links into a V-shape against the force of a spring. A first and a second check valve for allowing a flow from the fluid pressure source to each end chamber in a passage selectively communicating the pair of end chambers with the fluid pressure source;
The second check valve is provided with first and second valve actuators for opening the second check valve, and the inlet side portion of the first check valve is connected to the cylinders of the second valve actuator and the release actuator by a second valve actuator.
The inlet side portion of the check valve communicates with each of the cylinders of the first valve actuator and the release actuator, and when the locking rod moves inward, the cam pushes the rod of the valve actuator, thereby causing the reverse of the valve actuator. The stop valve is opened.

[Operation] When the actuator piston is in the neutral position, the pair of links of the neutral locking mechanism are linearly expanded by the force of the spring, and the pair of locking rods are pressed against the opposite ends of the piston rod. Is held in the neutral position. At this time, the rod of the valve actuator is engaged with the small diameter portion (cam) of the locking rod by the force of the spring, and each check valve is closed by the force of the spring.

For example, when pressurized oil (or pressurized air) is pushed to open the right check valve and supplied to the right end chamber of the actuator, the piston is pushed to the left. At the same time, the pressure oil enters the cylinder of the release actuator, the connecting point of the pair of links is pushed up by the cam, and the pair of links is bent into an inverted V shape,
The right locking rod is pushed to the left by the piston rod. Also, pressurized oil enters the left valve actuator,
The left check valve is pushed open against the force of the spring. Accordingly, the oil in the left end chamber of the actuator is returned to the oil tank via the left check valve. When the right locking rod is pushed to the left, the large diameter portion (cam) of the right locking rod pushes down the rod of the valve actuator, and the right check valve is kept open.

Here, if a hydraulic pressure failure occurs, the left check valve closes,
The right check valve is pushed open by the large diameter portion (cam) of the right locking rod. Therefore, even if the piston of the actuator is pushed to the left by an external force, the oil in the left end chamber is trapped by the left check valve, so that the piston is prevented from moving to the left. On the other hand, the pair of links are linearly expanded by the force of the return spring, and the right piece of the piston rod is pushed to the right by the right locking rod, thereby returning the piston to the neutral position. The oil in the right end chamber of the actuator is returned to the outside through the open right check valve, and the left end chamber is under negative pressure.

FIG. 1 is a side sectional view of an actuator runaway prevention device according to the present invention. Actuator 26 has piston 21 fitted in cylinder 24 to define end chambers 22, 22a. Both ends of a piston rod 23 connected to the piston 21 project outward from the cylinder 24. Both ends of the piston rod 23 are connected to rear wheel nuts via tie rods. Piston rod
The pieces 17, 17a each formed of a disk or an arm are connected to both ends of 23. Locking rods 16 and 16a that can abut on the contact pieces 17 and 17a are slidably supported by protruding walls 24a that project radially outward from both ends of the cylinder 24. Joints connected to inner ends of rocking rods 16 and 16a
Between the ends 15 and 15a, both ends of a neutral locking mechanism A composed of a pair of links 13 that are flexibly connected by connecting pins 10 are connected by pins 14.

The neutral locking mechanism A is urged to bend in a V-shape in the figure by a return spring 12 wound around the connecting pin 10 and having both ends locked to each link 13, and the roller 10 a supported by the connecting pin 10 is released. It comes into contact with the cam 8a of the actuator B.
The cam 8a is connected to an intermediate portion of the piston 8, and the piston 8
Are fitted to cylinders 9, 9a formed on the wall of the cylinder 24.

Check valves 6, 6a are disposed on both end walls of the cylinder 24, and are configured to be opened by rods of a valve actuator. In the neutral position of the actuator 26, the left check valve 6 urges the valve body 7 made of a ball toward the conical valve seat by the spring 5. At the same time, the piston 4 connecting the rod 2 of the valve actuator comes into contact with the step of the cylinder 3, and the end of the rod 2 is engaged with the small diameter portion 16b (cam) of the locking rod 16.
The right check valve 6a is configured similarly to the left check valve 6.

A passage communicating with the pipe 27 passes through the check valve 6 and is actuated.
The end chamber 22 of the actuator 26 can communicate with the end chamber 22 of the actuator 26 via a check valve 6a. The control valve 20 enables one of the pipes 27 and 27a to be selectively connected to the discharge port of the hydraulic pump 19 and the other to be selectively connected to the oil tank 18.

Next, the operation of the actuator runaway prevention device according to the present invention will be described. When the control valve 20 is moved rightward from the neutral position shown in FIG. 1, the piston of the actuator 26
21 moves to the left. That is, the pressure oil of the hydraulic pump 19 is supplied to the end chamber 22a via the control valve 20, the pipe 27a, and the check valve 6a,
The piston 21 is pushed to the left. At the same time, the pressure oil in the pipe 27a enters the cylinder 9 of the release actuator B, and the piston 8
Is pushed rightward, and the neutral locking mechanism A is bent by the cam 8a into an inverted V shape against the force of the return spring 12. Also, tube 27a
Is supplied to the cylinder 3 of the left valve actuator via the cylinder 9, the rod 2 is pushed down together with the piston 4, and the check valve 6 is opened. Accordingly, the oil in the end chamber 22 is returned to the oil tank 18 via the check valve 6, the pipe 27, and the control valve 20.

With the leftward movement of the piston 21 and the piston rod 23,
The locking rod 16a is pushed leftward by the contact piece 17a, and eventually the rod 2 is pushed down by the large diameter portion (cam) of the locking rod 16a, and the check valve 6a is maintained in the open state. At this time, the left locking rod 16 presses the joint 15 against the inner surface of the protruding wall 24a and does not move.

Here, when a hydraulic pressure failure occurs, that is, when the hydraulic pressure of the pipes 27 and 27a is released, the check valve 6 is closed, and the check valve 6a is
It is pushed open by the large diameter part (cam) of 16a. Therefore, even if an external force such as pushing the piston 21 to the left is applied to the rear wheel, the end chamber 22 is sealed by the check valve 6,
The leftward movement of the piston 21 is prevented. On the other hand, the link 13 of the neutral locking mechanism A expands linearly and the right locking rod 16 is opened.
a is pushed to the right and abuts us 17a, piston rod 23
Is pushed back to the right. Oil in end chamber 22a is checked valve 6a, pipe 27a
, And is discharged to the outside, and the end chamber 22 has a negative pressure. When the neutral locking mechanism A is linearly expanded, the locking rods 16, 16a
Abuts against the contact pieces 17 and 17a of the piston rod 23, and the actuator 26 is held at the neutral position. At this time, the check valve 6a is also closed.

The link 13 of the neutral locking mechanism A is not linear,
If the roller 10a is brought into contact with the cam 8a while the connecting pin 10 is moved slightly below the straight line connecting the left and right pins 14, the external force acting on the actuator 26, i.e. Piston against external force pushing left
The movement of 21 is effectively blocked.

FIG. 2 is a schematic configuration diagram in which the above-described actuator runaway prevention device is applied to a four-wheel steering vehicle. For example handle
When turning 31 to the right, the control valve 32 is actuated, the tie rod 35a is pushed leftward by the actuator of the front wheel steering mechanism 33, and the nut arm 35 supporting the front wheel 36 is rotated clockwise about the support shaft 34. , The front wheel 36 is deflected to the right. In connection with the operation of the handle 31, the spool of the control valve 20 moves rightward, the piston rod 23 connected to the piston 21 of the actuator 26 moves leftward, and the knuckle arm 38 supporting the rear wheel 39 moves the support shaft 37. It rotates counterclockwise as the center, and the rear wheel 39 is deflected to the left (opposite phase with the front wheel). Thus,
The small turning performance of the vehicle is exhibited.

In the embodiment shown in FIG. 3, instead of using the cam 8a for the release actuator B, a three-pronged lever 29 is provided. The lever 29 is rotatably supported on the wall of the cylinder 24 by the support shaft 28, and both ends abut against the protrusions 13 a of the pair of links 13,
An arm 29a projecting from the intermediate portion of the lever 29 is engaged with the concave portion of the piston 8 of the release actuator B. Cylinder 9, 9a
When pressure oil is supplied to one of the two links, the lever 29 is rotated, and the protrusion 13a of the one link 13 is pushed up, so that the pair of links 1
3 is bent into an inverted V shape, and the locking action of the locking rods 16 and 16a is released.

In the embodiment shown in FIG. 4, the release actuator B is 1
Racks 41 which are parallel to each other are formed on the rods of the pistons 44 respectively fitted to the pair of cylinders 9, 9a, and a pinion 43 meshing between the pair of racks 41 is formed by a support shaft 42 on the wall of the cylinder 24. Supported by The ends of the rack 41 are abutted against the protrusions 13a of the left and right links 13. When the pressure oil is supplied to one of the cylinders 9 and 9a, the one link 13 is pushed up by the rack 41, and the neutral lock mechanism A is bent into an inverted V shape.

[Effects of the Invention] As described above, according to the present invention, an actuator is formed by connecting a contact piece to both ends of a piston rod integral with a piston which is inserted into a cylinder to define a pair of end chambers. A pair of locking rods parallel to the piston rod are supported on a pair of projecting walls extending radially outward from both ends so as to be slidable and abutable on the aforesaid piece, and a cam is provided at an inner end of the locking rod. A contactable joint is provided on the inner surface of the protruding wall, a pair of links is connected between the pair of locking rod joints, and the pair of links is formed into a V-shape against the force of a spring. A first and a second check valve for allowing a flow from the fluid pressure source to each end chamber in a passage selectively communicating the pair of end chambers with the fluid pressure source; The first and second check valves are provided with first and second valve actuators for opening the first and second check valves, respectively. The mouth portion communicates with the second valve actuator and the cylinder of the release actuator, and the inlet portion of the second check valve communicates with the first valve actuator and the cylinder of the release actuator. When moving inward, the rod of the valve actuator is pushed by the cam to open the check valve, so that the following effects are obtained.

At the same time that the actuator starts up from the neutral position, pressurized fluid pushes one check valve open and is sent to one end chamber of the actuator, and also to the valve actuator of the other check valve and the other check valve. The valve is also opened. Further, the pressurized fluid is sent to the cylinder of the release actuator, and the pair of links is bent, so that the operation of the neutral locking mechanism and the actuator can be smoothly performed, and the actuator can be started smoothly.

If a hydraulic pressure failure occurs while the actuator is moving to one side from the neutral position, one of the check valves is closed in connection with the operation of the locking rod of the neutral locking mechanism, so that the direction opposite to the neutral direction of the actuator due to external force. (A runaway) is prevented, and the piston rod of the actuator is gradually returned to the neutral position with the linearly expanding movement of the pair of links. Therefore, if the present invention is applied to, for example, an actuator for steering a rear wheel of a four-wheel steering vehicle, it is easy to start the actuator from a neutral position, and when a hydraulic pressure failure occurs, the rear wheel is returned to a straight-ahead position; Very secure because it is locked.

[Brief description of the drawings]

FIG. 1 is a side sectional view of an actuator runaway prevention device according to the present invention, FIG. 2 is a plan view showing a schematic configuration of a four-wheel steering vehicle equipped with the actuator, and FIGS. It is a side view which shows an Example. A: Neutral locking mechanism, B: Release actuator, 3: Valve actuator cylinder, 6, 6a: Check valve, 9,9a: Release actuator cylinder, 12: Return spring, 13: Link, 16, 16a:
Lock rod, 17, 17a: this piece, 22, 22a: end chamber, 24a: protruding wall, 26:
Actuator

Claims (1)

(57) [Claims] 1. An actuator is formed by connecting an abutment to both ends of a piston rod integral with a piston which is inserted into a cylinder to define a pair of end chambers, and extends radially outward from both ends of the cylinder. A pair of locking rods parallel to the piston rod are slidably supported on the pair of protruding walls so as to be able to abut against the abutting piece, and a cam and an inner surface of the protruding wall are abutted on an inner end of the locking rod. And a release actuator for connecting a pair of links between the pair of locking rod joints and bending the pair of links into a V-shape against the force of a spring. A first and second check valve is provided in a passage selectively communicating with a pair of end chambers of the cylinder to a fluid pressure source to allow flow from the fluid pressure source to each end chamber. 1st opening this to stop valve
A second valve actuator, wherein the first check valve inlet side portion is connected to each of the cylinders of the second valve actuator and the release actuator, and the second check valve inlet side portion is connected to the first valve actuator. The runaway of the actuator is characterized in that the valve of the valve actuator is pushed by the cam to open the check valve when the locking rod moves inward, and the check valve is opened when the locking rod moves inward. Prevention device.