JP3070203B2 - Rear wheel suspension for reach forklift - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rear wheel suspension system for a reach forklift.

[0002]

2. Description of the Related Art Generally, in a rear wheel suspension system of a reach forklift, a drive wheel and a driven wheel are supported by a body frame via a link mechanism, and the drive wheel is fixed by a wheel pressure adjusting spring. Load is applied. Here, when the drive wheel is worn, the set load of the wheel pressure adjusting spring is released, the load applied to the drive wheel is reduced, and the wheel is liable to slip, and the wear of the drive wheel is further promoted. To solve such a problem,
Measures have been taken to readjust the set load of the wheel pressure adjustment spring when the drive wheel has worn to some extent, but this adjustment must be performed while measuring the load on the drive wheel (or driven wheel). It can be a very difficult task even in a specialized maintenance shop.

[0003] Further, by reducing the spring constant of the wheel pressure adjusting spring, it is possible to secure the minimum load of the driving wheel required for slip prevention to a fully worn state of the driving wheel without adjustment. However, there are advantages and disadvantages in reducing the spring constant of the wheel pressure adjusting spring. That is,
If the spring constant of the wheel pressure adjusting spring is low even if the driving wheel wears, the amount of change in the load applied to the driving wheel by the wheel pressure adjusting spring is small, which is advantageous for driving wheel wear. However, this advantageous property causes a decrease in vehicle stability during cargo handling, which is a serious drawback. More specifically, when the cargo is unloaded, the weight of the rear end of the vehicle is reduced because the center of gravity of the vehicle is located in front of the vehicle. In this state, acceleration in the lifting direction acts on the sprung system including the body frame. At this time,
For example, when a wheel pressure adjusting spring is interposed between the link mechanism and the vehicle body frame, the driving wheel has sufficient weight and the driving wheel remains grounded, but the spring constant of the wheel pressure adjusting spring is If it is low, the driven wheel will be lifted, and the vehicle stability will be reduced.

On the other hand, there has been proposed a spring provided with a stopper mechanism in order to prevent a decrease in vehicle stability due to a reduction in the spring constant of the wheel pressure adjusting spring as described above. The stopper mechanism includes a contact member on the body frame side and a contact member on the lower link side, and by contact between these contact members,
The swing stroke of the lower link is regulated. The swing stroke of the lower link is adjustable and needs to be adjusted periodically as the drive wheel wear progresses. As a device provided with such a stopper mechanism,
For example, the one described in Japanese Utility Model Application Laid-Open No. 63-149305 is known. In this apparatus, the swing stroke of the lower link can be adjusted according to the thickness of the shim and the screwing amount of the bolt.

[0005]

However, in such a conventional reach forklift rear wheel suspension device, the adjustment work associated with the drive wheel wear is relatively easy, but the abutting members of the stopper mechanism are difficult to adjust. In the configuration that regulates the swing stroke of the lower link by the contact of the lower link, the swing of the lower link until the regulation is abrupt, the change in vehicle behavior becomes too large, and the impact when the contact members collide with each other However, there was a problem that the size became large.

Accordingly, the present invention is directed to a rear wheel suspension for a reach forklift capable of improving vehicle stability and facilitating adjustment work associated with drive wheel wear while reducing the impact caused by the swing of the lower link. It is an object to provide a device.

[0007]

According to the first aspect of the present invention,
A link mechanism having a lower link connected to a drive wheel and a driven wheel supported on the body frame so as to be able to rotate around a predetermined axis, and interposed between the body frame and the drive wheel, A wheel pressure spring for applying a constant load; and a rear wheel of a reach forklift supported by the body frame so that the link mechanism allows the drive wheel and the driven wheel to swing up and down within a predetermined range. in the suspension system, said between lower link and the vehicle body frame, a backward moment before Symbol moment given to the lower link by a wheel pressure spring around a predetermined axis to the lower link, said higher wheel pressure spring
A biasing means for adjusting wheel pressure by applying a spring member having a spring constant is provided.

According to a second aspect of the present invention, in addition to the configuration of the first aspect, the urging force of the urging means does not act on the lower link when the vehicle is horizontal, and the lower link is driven from the position when the vehicle is horizontal. Only when it turns in the direction of the
It is characterized by working on the lower link. According to a third aspect of the present invention, in addition to the configuration of the first or second aspect, the swing stroke of the lower link in the floating direction of the driven wheel is restricted by being interposed between the lower link and the vehicle body frame. A swing stroke adjusting means having an adjusting function for adjusting the swing stroke is provided, and by adjusting the swing stroke according to the drive wheel wear by the swing stroke adjusting means, the biasing force of the biasing means acting on the lower link is reduced. It is characterized by returning to the initial state before the wear of the drive wheels progresses.

[0009]

According to the first aspect of the invention, when the vehicle body frame rises, the rotation of the lower link in the floating direction of the driven wheel is suppressed by the urging force of the urging means. In particular, when the ascending acceleration of the vehicle body frame is large, the lower link side abuts on the vehicle body frame side after the lower link is sufficiently decelerated by the urging, so that the impact is reduced. Also, by lowering the wheel pressure spring, when the driving wheel is pushed up during traveling, the wheel pressure spring bends, but the spring constant is small, so that an increase in the load on the driving wheel is suppressed. On the other hand, when the driven wheel is pushed up during traveling, the urging means is compressed and the wheel pressure spring expands, so that the load applied to the driven wheel increases, and the shock during traveling on a rough road is greatly reduced.

According to the second aspect of the present invention, in addition to the function of the first aspect, it is possible to prevent the additional load due to the wheel pressure spring from being affected by the urging force of the urging means when the vehicle is horizontal. According to the third aspect of the present invention, in addition to the operation of the first or second aspect, the urging force of the urging means acting on the lower link is driven only by adjusting the swing stroke of the lower link by the swing stroke adjusting means. It is possible to automatically return to the initial state before the wear of the wheel progresses.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the drawings. 1 to 3 are views showing one embodiment of a rear wheel suspension device of a reach forklift according to the present invention. First, the configuration will be described.

1 to 3, reference numeral 1 denotes a link mechanism, and the link mechanism 1 has a lower link 2, an upper link 3, and a support bracket 4. The lower link 2 and the upper link 3 are rotatably supported by a support bracket 4 fixed to the vehicle body frame 5. More specifically, the lower link 2 is rotatable around the center shaft 6, that is, is supported by the vehicle body frame 5 so as to be rotatable around a predetermined axis. One end of the lower link 2 is connected to a driving wheel 7 and the other end is a driven wheel 8.
It is connected to. On the other hand, the tip of the upper link 3 is rotatably connected to the drive wheel 7. Accordingly, the drive wheel 7 and the driven wheel 8 are supported by the body frame 5 by the link mechanism 1 so as to be able to swing up and down within a predetermined range.

Reference numeral 9 denotes a wheel pressure adjusting first spring (wheel pressure spring) having a sufficiently small spring constant. The wheel pressure adjusting first spring 9 is contracted between the support bracket 4 and the lower link 2. I have. Therefore, the first wheel pressure adjustment
The spring 9 is interposed between the vehicle body frame 5 and the drive wheels 7 to apply a constant load to the drive wheels 7.
In this embodiment, the wheel pressure of the drive wheel 7 can be adjusted by the first wheel pressure adjusting spring 9.

Here, between the lower link 2 and the vehicle body frame 5, a second spring (biasing means) 10 for adjusting the wheel pressure , which is a spring member, is interposed. Urges the lower link 2 so that a moment in the opposite direction to the moment applied to the lower link 2 about the center shaft 6 by the first wheel pressure adjusting spring 9 is applied to the lower link 2 . The spring
The constant is determined by the wheel pressure spring (wheel pressure adjustment first spring).
(9) It is higher than the spring constant of (9). See Figure 2 for details.
As shown in the figure, the lower end of the second wheel pressure adjusting spring 10 is supported by the lower link side seat 11 and the upper end thereof is the frame side seat 12.
It is supported by. Lower link side seat 11 is lower link 2
, And also serves as a reinforcing member of the lower link 2. A shim 13 and a spring guide 14 are fixed to the lower link side seat portion 11 by bolts 15, so that the spring guide 14 can be removed. In addition,
The spring guide 14 may be formed integrally with the lower link 2 similarly to the lower link side seat 11.

On the other hand, the frame side seat portion 12 also serves as a spring guide, and its upper end is in contact with the tip of an adjustment bolt 16 screwed to the support bracket 4. Adjustment bolt 16
Is only in contact with the frame side seat portion 12 when the vehicle is horizontal, and the second wheel pressure adjusting spring 10 is held at a free length. Accordingly, the urging force of the wheel pressure adjusting second spring 10 does not act on the lower link 2 when the vehicle is horizontal, and the lower link 2 moves from the position when the vehicle is horizontal to the driven wheels 8.
Only when it turns in the floating direction (the direction of arrow A in FIG. 2), it acts on the lower link 2.

Further, the lower link side seat portion 11 and the shim 1
3, the spring guide 14, the frame side seat portion 12, and the adjustment bolt 16 are interposed between the lower link 2 and the vehicle body frame 5 to regulate the swing stroke of the lower link 2 in the floating direction of the driven wheel 8. A swing stroke adjusting means having an adjusting function for adjusting the swing stroke is constituted. That is, when the lower link 2 swings in the direction of arrow A in FIG.
The spring guide 14 and the frame side seat 12 abut against each other to inhibit the lower link 2 from further swinging. Further, by changing the screwing amount of the adjustment bolt 16, the clearance dimension L, which is the swing stroke of the lower link 2, can be adjusted. The gap L can be adjusted by adjusting the thickness of the shim 13.

Here, when the wear of the drive wheel 7 progresses,
The lower link 2 rotates in the direction of arrow A in FIG.
And the second wheel pressure adjusting spring 10 is shortened from its free length. In this case, by loosening the adjusting bolt 16 once and then screwing it in until the tip of the bolt comes into contact with the frame side seat portion 12, the gap dimension L is restored to the initial value, and at the same time, the wheel pressure adjusting second spring 10 is free. Recover to length. Therefore, by adjusting the swing stroke by the swing stroke adjusting means according to the drive wheel wear, the urging force of the wheel pressure adjusting second spring 10 acting on the lower link 2 is changed to the initial state before the wear of the drive wheel 7 progresses. To return to.

Next, the operation will be described. (A) At the time of cargo handling When the body frame 5 rises, the lower link 2 rotates in the direction of arrow A in FIG. At this time, since the spring constant of the first wheel pressure adjusting spring 9 is sufficiently small, the decrease in the load applied to the drive wheel 7 is small. On the other hand, since the second wheel pressure adjusting second spring 10 on the opposite side has a sufficiently large spring constant and is compressed, the urging force of the second wheel pressure adjusting second spring 10 for urging the lower link 2 is equal to the lower link. Rotation of the driven wheel 8 in the direction indicated by the arrow A in FIG. When the acceleration of the body frame 5 is large, the lower link 2 is sufficiently decelerated by the second spring 10 for adjusting the wheel pressure.
Since the abutment 12 comes into contact, the impact is reduced. (A) Running When the drive wheel 7 is pushed up, the wheel pressure adjusting first spring 9 bends, but the load on the drive wheel 7 does not increase significantly because the spring constant is small. Further, since the second spring 10 for adjusting the wheel pressure is in the extending direction, no urging force works. On the other hand, when the driven wheel 8 is pushed up, the second spring 10 for adjusting the wheel pressure is compressed, and the first spring 9 for adjusting the wheel pressure is expanded, so that the load applied to the driven wheel 9 increases, and when the vehicle is traveling on a rough road. Shock is greatly reduced.
This is because the lower link 2 in the drive wheel push-up direction is generally used.
Since the swing stroke of the lower link 2 is set to be large, swinging freely without suppressing the swing of the lower link 2 makes it easier to get over a road surface protrusion. On the other hand, the gap dimension L is a rocking stroke of the driven wheel push-up direction of the lower link 2, which are set smaller in order to improve the handling stability, the lower link until the spring guide 14 is brought into contact with the frame side seat 12 2 often swings. Therefore, by increasing the load applied to the driven wheel 8 until the collision between the spring guide 14 and the frame side seat portion 12, the impact of the collision is reduced and the traveling is stabilized. (C) When the drive wheel is worn When the drive wheel 7 is worn, the lower link 2 rotates in the direction of arrow A in FIG. 2, the second spring 10 for adjusting wheel pressure contracts, and the first spring 9 for adjusting wheel pressure expands. . Therefore, the clearance dimension L decreases as the driving wheel load decreases. When the drive wheel 7 is worn in this way, the adjusting bolt 16 is once loosened as described above, and screwed again until the tip of the bolt comes into contact with the frame side seat portion 12 and fixed with the nut 16a. By this adjustment, the urging force and the gap dimension L of the second wheel pressure adjusting spring 10 return to the initial state. Further, since the first spring 9 for adjusting the wheel pressure has a small spring constant, the load fluctuation caused by the extension of the first spring 9 for adjusting the wheel pressure does not matter.

As described above, in the present embodiment, the first spring 9 for adjusting the wheel pressure is reduced in spring constant.
Without the adjustment of the wheel pressure adjusting first spring 9 until the fully worn state, the minimum load of the drive wheel required for slip prevention can be secured, and the progress of wear of the drive wheel 7 can be suppressed. Further, by providing the second spring 10 for adjusting the wheel pressure, it is possible to prevent the driven wheels 8 from floating even when the vehicle body frame 5 floats during loading and unloading. After the lower link 2 is sufficiently decelerated by the second wheel pressure adjusting spring 10, the lower link side seat portion 11 and the frame side seat portion 12 come into contact with each other, so that the impact can be reduced.

Further, when the driving wheel 7 is pushed up during traveling, an increase in the load on the driving wheel 7 can be suppressed. On the other hand, when the driven wheel 8 is pushed up during traveling, the load applied to the driven wheel 8 increases, and the shock during traveling on a rough road can be significantly reduced. Further, when the driving wheel is worn, the adjusting bolt 16 is loosened once, screwed again until the tip of the bolt contacts the frame side seat portion 12, and fixed by the nut 16a. The biasing force and the gap dimension L can be returned to the initial state, and the adjustment work can be made very easy. In this embodiment, if necessary, the adjustment of the wheel pressure adjusting first spring 9 and the adjustment of the swing stroke can be performed.

Therefore, it is possible to improve the stability of the vehicle and to facilitate the adjustment work due to the wear of the drive wheels, while reducing the impact caused by the swing of the lower link. In this embodiment, an increase in the number of components is small, and an increase in cost can be suppressed to a minimum. Further, a wear sensor for detecting wear of the drive wheel 7 may be provided, and the gap L may be automatically adjusted by rotating the adjustment bolt 16 based on the detection result of the wear sensor.

[0022]

According to the first aspect of the present invention, since the biasing means is provided, even if the wheel pressure spring is reduced in spring constant, the impact accompanying the swing of the lower link is reduced and the vehicle is stabilized. Operability can be improved, and the adjustment work accompanying the drive wheel wear can be facilitated.

According to the second aspect of the invention, in addition to the effect of the first aspect, it is possible to prevent the urging force of the urging means from affecting the additional load by the wheel pressure spring when the vehicle is horizontal. According to the third aspect of the present invention, in addition to the operation of the first or second aspect, the urging force of the urging means acting on the lower link is adjusted only by adjusting the swing stroke of the lower link by the swing stroke adjusting means. Thus, it is possible to automatically return to the initial state before the wear of the drive wheels progresses.

[Brief description of the drawings]

FIG. 1 is an overall schematic diagram of a rear wheel suspension device of a reach forklift according to the present invention.

FIG. 2 is an enlarged view of a main part including a partial cross section of the rear wheel suspension device in FIG.

FIG. 3 is a top view of a main part of the rear wheel suspension device in FIG. 1;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Link mechanism 2 Lower link 5 Body frame 7 Driving wheel 8 Follower wheel 9 First spring for wheel pressure adjustment (wheel pressure spring) 10 Second spring for wheel pressure adjustment (biasing means) 11 Lower link side seat (oscillation) Stroke adjusting means) 12 Frame side seat (oscillating stroke adjusting means) 13 Shim (oscillating stroke adjusting means) 14 Spring guide (oscillating stroke adjusting means) 15 Bolt (oscillating stroke adjusting means) 16 Adjusting bolt (oscillating) Stroke adjusting means)

──────────────────────────────────────────────────続 き Continued on front page (58) Field surveyed (Int. Cl. ⁷ , DB name) B60G 9/00

Claims (3)

(57) [Claims] 1. A link mechanism having a lower link supported by a body frame and connected to a driving wheel and a driven wheel so as to be able to rotate around a predetermined axis, and interposed between the body frame and the driving wheel. And a wheel pressure spring for applying a constant load to the drive wheels. The link mechanism supports the drive wheels and the driven wheels on the vehicle body frame so as to be able to swing up and down within a predetermined range. in rear-wheel suspension system reach truck, between the lower link and the vehicle body frame, a backward moment before Symbol moment given to the lower link by a wheel pressure spring around a predetermined axis to the lower link,
Given by a spring member having a higher spring constant than the wheel pressure spring.
A rear wheel suspension device for a reach forklift, wherein a biasing means for adjusting wheel pressure is provided. 2. The biasing force of the biasing means does not act on the lower link when the vehicle is horizontal, but acts on the lower link only when the lower link is turned from the position when the vehicle is horizontal in the direction in which the driven wheel rises. The rear wheel suspension device for a reach forklift according to claim 1, wherein: 3. A swing stroke adjuster interposed between the lower link and the vehicle body frame, the swing stroke of the lower link being regulated in the direction in which the driven wheel lifts up, and an adjusting function for adjusting the swing stroke. Means for adjusting the oscillating stroke according to the drive wheel wear by the oscillating stroke adjusting means so that the urging force of the urging means acting on the lower link returns to the initial state before the wear of the drive wheels progresses. The rear wheel suspension device for a reach forklift according to claim 1 or 2, wherein: