JP3109280B2 - Swing control structure for rear-wheel steered vehicles - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an industrial vehicle such as a forklift having a front axle of a rigid axle type and a rear axle of a swing axle type, and more particularly to an amount of vertical swing of a rear axle with respect to a vehicle body. The present invention relates to a swing control structure for controlling.

[0002]

2. Description of the Related Art Generally, in an industrial vehicle such as a forklift in which a front axle is a rigid axle and a rear axle is a swing axle, the rear axle swings freely during normal running to improve riding comfort. At the time of cargo handling operation, it is desired to be in a rigid state in order to secure stability.

That is, if the rear axle is in a rigid state during normal running, the swinging of the rear axle is directly input to the vehicle body to deteriorate the riding comfort, and the roll moment at the time of turning becomes large, so that the vehicle easily falls down. Become. When the swinging of the rear axle is in a free state during the cargo handling operation, as shown in FIG. 7, the grounding points A and B of the left and right wheels of the front axle 13, which is a rigid axle, and the swinging shaft. The triangle connecting the center part (connection part to the vehicle body) S of the rear axle is the reference plane H for vehicle stability. In other words, the stability condition is that the vertical line of the center of gravity of the vehicle is located within this triangle, and if the center of gravity moves out of the reference plane H of this triangle, it falls over.

On the other hand, when the rear axle is in a rigid state during the cargo handling operation, the reference plane H is provided with the ground points A and B of the left and right wheels 13 of the front axle and the rear axle as shown in FIG. It is a rectangle connecting the ground points C and D of the left and right wheels 1, and the margin of left and right movement of the center of gravity of the vehicle is larger than in the free state. In the free state of the rear axle, the vehicle tilts as the vehicle center of gravity moves out of the triangular reference plane H, that is, when the rear axle relatively swings, the rear axle comes into contact with a stopper on the vehicle body side. The rear axle is locked and the reference plane H
Changes from a triangular portion as shown in FIG. 7 to a rectangular portion as shown in FIG. 8, but since the reference plane H changes rapidly, the center of gravity moves out of the rectangular reference plane H due to inertial force. Easy to fall.

[0005] To prevent this, for example,
A method described in Japanese Utility Model Laid-Open Publication No. 55-165813 has been proposed. This is because the left and right ends of the rear axle are respectively connected to the vehicle body via a hydraulic cylinder device, and the opening and closing for the opening and closing incorporated in the pipeline communicating the oil chambers so that the piston rod of the hydraulic cylinder device can move freely. When the vehicle is running, the solenoid valve is controlled to switch to a conduction position when rotating and to a shut-off position when stopped by a signal from a detector that detects the presence or absence of rotation after the transmission in the traveling drive system. The rear axle can be freely swung, and when stopped, the rear axle is restrained and locked by a cylinder device to be in a rigid state.

[0006]

However, when the above-mentioned swing control device is mounted, the above-mentioned devices such as the cylinder device, the cylinder control device, and the detector are required, so that the manufacturing cost is high, and furthermore, In the event that the system fails due to disconnection or the like, the vehicle is likely to fall over during cargo handling without locking the swing of the rear axle when the vehicle stops. Moreover, if a fail-safe mechanism is added to avoid such a risk, there is a problem that the cost is further increased.

Further, in a vehicle described in Japanese Patent Application No. 3-192403, in which a king pin is provided with a caster angle in order to improve driving operability, the caster angle is provided. As a result, at the time of steering, one of the left and right rear wheels attempts to dive into the horizontal plane, and the other axle swings up and down because the other is going to lift. For this reason, in a forklift or the like that often performs stationary full steering, there is a problem that if the rear axle is kept in a rigid state in order to secure vehicle stability during a cargo handling operation, the vehicle tilts during stationary steering.

The present invention has been made in view of the above-mentioned problems, and has an object to provide a swing control structure which is inexpensive to manufacture and can be applied to a vehicle having a caster angle.

[0009]

In order to achieve the above object, a swing control structure for a rear-wheel-steered vehicle according to the present invention is connected to a vehicle body at a central portion in a vehicle width direction, and the vehicle body is centered on the connection portion. In a rear-wheel steering vehicle having a swing axle-type rear axle that swings up and down relatively to, an elastic body is interposed between a rear axle and a vehicle body-side member located above the rear axle, The elastic member is an elastic member disposed near the connecting portion of the rear axle to the vehicle body when the swing angle is within a predetermined angle range.
Generates a restoring force against the above swing, and the swing angle is
When the angle exceeds a certain angle, the outer side in the vehicle width direction than the vicinity of the connection part
It is characterized in that it is set to generate a restoring force corresponding to the swing angle of an elastic material portions located. After the above
The connecting part of the axle to the vehicle body is the swing center of the rear axle (switch
Center).

At this time, it is preferable that a part of the elastic body is disposed at a central portion in the vehicle width direction, and the elastic body is always brought into contact with the vehicle body side member and the rear axle with a predetermined bending. .

[0011]

[Function] The rear axle swings and the vehicle body rolls,
When the rear axle swings up and down with respect to the vehicle body, one of the left and right sides of the rear axle relatively approaches the lower surface of the vehicle body. Soshi
If the swing angle exceeds a predetermined angle,
The elastic body interposed outside in the vehicle width direction is compressed and bent, and the elastic force of the elastic body urges the rear axle relatively away from the lower surface of the vehicle body. This is because, as the swing angle increases, the bending due to the compression increases, and the urging force increases according to the amount of the bending, so that the rear axle gradually becomes rigid as the swing angle increases.

[0012] In the <br/> small state in which the swing angle does not exceed a predetermined swing angle, elastic portions <br/> other than the vicinity of the swing center portion does not contact the vehicle body side or the rear axle side or place manner, for example, by providing a Sorabo chamber to the elastic body section, and the urging force, i.e. a restoring force to zero or very small. When the vehicle is traveling, turning, or stationary, the up-and-down swing of the rear axle is usually small. Therefore, in the region up to the swing angle, the urging force from the elastic body, that is, The restoring force is zero or small, and the swinging of the rear axle freely swings without being restricted by the elastic body.

When the vehicle is tilted by a predetermined angle or more during the cargo handling operation, the lower part of the vehicle body on the inclined side approaches the rear axle, and the rear axle swings relatively upward. To compress the elastic body. When the vehicle body leans more than a predetermined amount, the elastic body urges the vehicle body in a direction to prevent the vehicle body from leaning, and gradually brings the rear axle into a rigid state.
For this reason, the change of the reference plane for vehicle stability from the triangular shape as shown in FIG. 7 to the square shape as shown in FIG. 8 due to the tilting of the vehicle body becomes gentle, thereby preventing the vehicle from tipping over during cargo handling.

Usually, a stopper is provided on the vehicle body side member so that the rear wheels do not interfere with the vehicle body, and the rear axle is restricted so as not to incline beyond a predetermined angle. Since the elastic body is bent and absorbs the impact before the stopper collides with the contact member of the rear axle, the impact when the stopper collides with the contact portion is buffered, so that the stopper is used when traveling on rough roads. To prevent the stopper from being damaged.

Further, if a part of the elastic body is brought into contact with the vehicle body side member and the rear axle with a predetermined bending at the center portion of the vehicle width, the swinging center portion of the rear axle is always kept by the elastic body. As the bush supporting the rear axle is worn down, the rattle of the rear axle is suppressed. At this time,
Since the elastic body is located at the center of the rear axle, that is, above the connection between the rear axle and the vehicle body, the elastic body does not restrict the swing of the rear axle so much.

[0016]

An embodiment of the present invention will be described with reference to the drawings. The industrial vehicle according to the present embodiment is a forklift, and a fork that can move up and down along a mast is provided on the front side of the vehicle body. As shown in FIG. 1 and FIG. 2, right and left rear wheels 1 of the vehicle are rotatably supported by knuckle spindles 2, respectively, and the left and right knuckle spindles 2 are rear axles extending in the vehicle width direction. Each end of the steering axle 3 is connected via a king pin 4.

The steering axle 3 has a bell crank 5
Are rotatably supported, and the bell crank 5 is
The steering operation force is transmitted via the drag link 6 so that the steering operation force can be rotated around the bell crank shaft. The king pin 4 is rotated via the tie rod 7 by the rotation of the bell crank 5, and the left and right rear wheels 1 are rotated around the axis K of the king pin 4.

The steering axle 3 is attached to the vehicle body frame so as to be inclined along the vehicle front-rear direction. More specifically, the steer axle 3 has a box-shaped central portion in the vehicle width, and as shown in FIG.
a is inclined so that the rear side of the vehicle body is lower than the front side of the vehicle body, and a swing shaft 8 is disposed so as to penetrate the box portion 3a horizontally in the front-rear direction of the vehicle body. Both ends are rotatably connected to the bracket 9 on the vehicle body side, so that the steering axle 3 is swingably connected to the vehicle body about the center portion in the vehicle width direction. The left and right can swing up and down.

As a result, the axis K of the king pin 4 connecting the steer axle 3 and the knuckle spindle 2 is inclined to give the rear wheel 1 a caster angle. A swing control rubber 10 is attached to the upper surface of the box portion 3a. Above the swing control rubber 10, a pressure contact plate 11 having a horizontal lower surface is fixed to a vehicle body side member.

The upper surface of the swing control rubber 10 fixed to the upper surface of the box is horizontal in the vehicle longitudinal direction so as to be parallel to the press-contact plate 11 as shown in FIG. In the vehicle width direction, as shown in FIG. 5, a portion (a top portion) 10b located vertically above the swing center S of the steering axle 3 is symmetrically located below the surface formed by the press-contact plate 11 from left to right. The tapered surface 10a is formed outwardly at a predetermined angle θ.

The tapered surface 10a of the swing control rubber 10
Of the taper surface 10a when swinging during normal running
Is set to an angle that does not abut or slightly touches the pressure contact plate 11, for example, 2 degrees, so that the restoring torque of the elastic body 10 with respect to the swing angle of the steering axle 3 becomes as shown in FIG. . Stopper bolts 14 are provided on both left and right ends of the vehicle body frame, respectively, and a contact member 15 is provided on the upper surface of the steer axle 3 located below the stopper bolt 14 so that the tip end of the stopper bolt 14 collides.

In an industrial vehicle such as a forklift having the above-described configuration, when the swing of the steering axle 3 is small, such as during general running, as shown in FIG. The tapered surface 10a of the control rubber 10 does not contact. For this reason, the swing control rubber 10
Is not compressed and does not generate any restoring force, so there is no regulation by the swing control rubber 10, and the steer axle 3 swings freely to make the riding comfort worse or to increase the roll moment during turning. There is no.

When the steer axle 3 swings more than the inclination angle θ of the tapered surface 10a, the swing control rubber 10 is compressed by an amount corresponding to the swing angle, and the elastic force corresponding to the compression amount is used. Since the swing control rubber 10 is depressed in a direction in which the steer axle 3 is relatively separated from the vehicle body, the swing of the steer axle 3 is gradually prevented when the swing angle exceeds a predetermined swing angle θ.

Thus, when the vehicle body is tilted by a predetermined angle or more during the cargo handling operation, the swing control rubber 10 interposed between the lower surface of the vehicle body and the steering axle 3 is compressed by an amount corresponding to the tilt of the vehicle body, and the amount of compression is reduced. The steering axle 3 is urged in a direction to separate the lower surface of the vehicle body and the steering axle 3 with a restoring force (see FIG. 6) corresponding to the steering angle, so that the transition of the steering axle 3 from the free state to the rigid state with respect to the swing angle becomes smooth, From the triangular state as shown in FIG. 7 of the reference plane H with respect to the vehicle center of gravity, FIG.
The transition to the square state as shown in (1) becomes gentle, and overturning due to inertial force during cargo handling is prevented.

Also, when traveling on rough roads, etc., the stopper bolt 14
Since the swing control rubber 10 deflects and cushions the impact before colliding with the contact member 15, the impact force when the stopper bolt 14 collides with the contact member 15 is reduced, and the stopper bolt 14 Can be prevented from being damaged. If the top portion 10b of the swing control rubber 10 is constantly bent so as to be in contact with the pressure contact plate 11, the elastic force of the bent portion causes the steering axle 3 to be supported by the vehicle body. Even if the bush is worn, play in the vertical direction can be suppressed, and play in the front-rear direction of the steering axle 3 can also be suppressed.

At this time, since the top 10b is located at the center in the vehicle width direction, the force for suppressing the swing of the steer axle 3 is small and poses no problem. Further, in the above-described embodiment, the taper surface 10a directed in the vehicle width direction with respect to the swing control rubber 10.
, The restoring force of the swing control rubber 10 against the swing of the steer axle 3 is increased from a predetermined swing angle. However, as shown in FIG. By providing the layer 20 and setting the restoring force of the swing control rubber 10 against the initial bending by setting the upper surface of the rubber 10 in contact with the pressure contact plate 11 or the like, the steering axle 3 The restoring force of the swing control rubber 10 in the predetermined angle range may be reduced.

In the above embodiment, the steering axle 3
Is applied to a vehicle in which the caster angle is imparted to the rear wheel 1 by inclining the steering wheel, but is also applicable when the steering axle 3 is not inclined, and the swing control rubber 10 fixed to the steering axle 3 If the upper surface shape is set so as to be similar to that of the above embodiment, the same operation and effect can be obtained.

In the above embodiment, the steering axle 3
Although the rocking control rubber 10 is provided on the side, the rocking control rubber 10 may be provided on the vehicle body side, and an elastic body may be interposed such that a press-contact plate is provided on the upper surface of the steering axle 3 opposed vertically. In the above embodiment, a rubber body is used as the elastic body, but another elastic body such as a coil spring may be used.

Further, the position of the swing control rubber 10 between the vehicle body and the steer axle 3 is not limited to the central portion in the vehicle width direction as in the above-described embodiment, and the swing control rubber 10 is controlled to the left and right symmetric positions. You may interpose so that the rubber 10 may be located.

[0030]

As described above, in the swing control structure for a rear-wheel steered vehicle according to the present invention, the elastic body is interposed between the lower surface of the vehicle body and the rear axle, and the elastic body is disposed near the swing center of the rear axle.
A predetermined swing angle is set for the elastic part
Since it is configured to act when it exceeds, appropriate swing control of the rear axle can be performed, and the impact input to the stopper can be reduced. Also, the elastic body at the center of the vehicle width,
If the bush of the part supporting the rear axle is worn due to the elastic force caused by the bending, the backlash in the vertical direction will be suppressed and the back and forth direction will be suppressed. Play can also be suppressed.

[Brief description of the drawings]

FIG. 1 is a front view showing a swing control structure in a rear-wheel steering vehicle according to an embodiment of the present invention.

FIG. 2 is a plan view showing a swing control structure in the rear-wheel steered vehicle according to the embodiment of the present invention.

FIG. 3 is a side view showing a swing control structure in the rear-wheel steered vehicle according to the embodiment of the present invention.

FIG. 4 is a schematic diagram showing a swung state in a rear-wheel steered vehicle according to an embodiment of the present invention.

FIG. 5 is a diagram showing a state of a swing control rubber and a press-contact plate according to the embodiment of the present invention.

FIG. 6 is a diagram showing a relationship between a restoring torque and a swing angle in the elastic body of the embodiment according to the present invention.

FIG. 7 is a diagram showing a reference plane when the rear axle swings freely.

FIG. 8 is a diagram showing a reference plane when the rear axle is in a rigid state.

FIG. 9 is a view showing a state of an elastic body and a press-contact plate according to a second embodiment of the present invention.

[Explanation of symbols]

 Reference Signs List 1 rear wheel 3 steer axle (rear axle) 10 swing control rubber (elastic body)

Claims (2)

(57) [Claims] 1. A rear-wheel steering vehicle having a swing axle-type rear axle connected to a vehicle body at a central portion in a vehicle width direction and swinging up and down relative to the vehicle body about the connection portion, An elastic body is interposed between the rear axle and the vehicle body-side member located above the rear axle, and the elastic body is disposed near a connecting portion of the rear axle to the vehicle body when the swing angle is within a predetermined angle range.
Generates restoring force against the above swing only in the elastic part
When the swing angle exceeds the predetermined angle, the vicinity of the connecting portion
Swing control structures in wheel steering vehicle after, characterized in that it is configured to generate a restoring force corresponding to the swing angle of an elastic body portion located Rimokuruma widthwise outer. 2. A part of the elastic body is disposed at a central portion in a vehicle width direction, and the elastic body is always brought into contact with a vehicle body side member and a rear axle with a predetermined bending. The swing control structure for a rear-wheel-steered vehicle according to claim 1, wherein: