JP2739398B2 - Road Wheel Steering Device for Reach Type Forklift - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a reach-type forklift capable of steering a road wheel supported at the tip of a straddle arm, without increasing the width of the straddle arm. The present invention relates to a steering device capable of realizing steering of a road wheel with dimensions.

[0002]

2. Description of the Related Art In recent years, forklifts have been proposed in which a road wheel supported at the tip of a straddle arm is provided so as to be steerable and can travel in all directions. As shown in FIGS. 7 to 10, the forklift 1 includes a main body 2 and left and right straddle arms 10A protruding from the main body 2,
Each of the drive wheels 10L and 12R supports a steerable road wheel 12L and 12R.

[0003] Between the straddle arms 10A, 10A,
A mast 3 is provided which can slide forward and backward and can move up and down by a lift cylinder 5 to lock cargo handling devices 4 and 4 such as forks or various attachments.

[0004] The road wheel steering mechanism will be described in detail. The road wheel 12L is rotatably supported by a bearing shaft 14 via a bearing, and the bearing shaft 14 is a bracket having a substantially "L" shape when viewed from the front. It is fixed to 50.
On the upper surface of the bracket 50, a steering shaft 16A protruding upward is rotatably supported by a straddle arm 10A via a bearing B.

[0005] At the inner end of the bracket 50, a spur gear 51 cut out in a fan shape is fixed by bolts 52, and a driving gear 19 meshing with the fan-shaped spur gear 51 is driven by a driving shaft 17.
It is inserted in. The drive shaft 17 is provided in parallel with the steering shaft 16A, is rotatably supported by a boss 22, and has a timing pulley 18 fixed to the upper end thereof.

A steering motor 34L is fixed in the straddle arm 10, and a pinion 33 of the steering motor 34L has a single-stage reduction gear 31, an idle gear 32 formed coaxially therewith, and a rotation shaft via a two-stage reduction gear 30. 29 can be rotated.

Further, a timing pulley 25 is fixed to the upper end of the rotary shaft 29, and the torque of the steering motor 34L is transmitted to the timing pulley 18 of the drive shaft 17 via a timing belt 35, so that the load wheel 12L is You can steer. 9 and 10, an encoder 28 detects the steering angle of the road wheel 12L by engaging a gear 27 provided at the tip of the detection shaft with a gear 26 fixed to the rotation shaft. Is configured to obtain.

[0008] As shown in FIG.
The steering center of L is the axis of the steering shaft 16A and is eccentric to the outside of the forklift in the vehicle width direction from the center line of the road wheel 12L by a distance s, and the driving torque at the time of steering the road wheel Can be reduced. In addition, due to such a configuration, the width is enlarged in the width direction as compared with a straddle arm of a normal reach-type forklift (referred to as a reach-type forklift that cannot perform steering of a road wheel).

The other road wheel has the same configuration, and is symmetrical with respect to the center line of the forklift 1.

[0010]

However, since a forklift is usually required to carry out cargo handling work in a narrow warehouse passage, as described above, when the width of the straddle arm is widened, the forklift is moved in all directions. Even if the vehicle can run, there is a problem that the minimum passage width must be increased as a result, and the storage space for the load is reduced.

On the other hand, the shaft weight acts on the load wheels 12L and 12R, and particularly when the load is loaded on the cargo handling device 4, an extremely large shaft weight acts. There is naturally a limit in reducing the size of the bearing 21 described above, and it has been difficult to reduce the width of the straddle arm 10.

Further, when the eccentric distance s is set to be large in order to reduce the steering torque of the road wheel, the width of the straddle arm is further increased.

SUMMARY OF THE INVENTION The present invention has been devised in view of the above situation, and has as its object to provide a road wheel in a reach type forklift capable of extremely reducing the width of a straddle arm for supporting left and right road wheels so as to be steerable. To provide a steering device.

[0014]

SUMMARY OF THE INVENTION The present invention provides a guide member having an arcuate shape whose center can be located near the distal end of each of the left and right straddle arms and at the outer position in the width direction of the vehicle body. A guide member fixed to the upper surface and fixed to the arc-shaped guide body so as to be slidably fitted to the upper surface, and a load wheel is positioned from the vehicle body center side and the center of the load wheel in the width direction is the guide body. A bracket provided with a hanging portion rotatably supported at a predetermined distance from the center of the vehicle, and a gear cut out in an arc shape on the bracket and having the arc side facing the center of the vehicle body fixed to cover the guide body. The drive gear meshing with the arc gear is housed and arranged in each of the left and right straddle arms at a position closer to the center of the vehicle than the arc gear.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS. 1 to 6. The same parts as in the prior art are denoted by the same reference numerals.

An arcuate guide body G whose center can be located outside the forklift in the vehicle width direction is fixed to the distal ends of the left and right straddle arms 10.

As shown in FIG. 1, the guide body G has a base portion 37 having the largest diameter and a convex portion which is concentric with the base portion 37 and which is welded to the upper surface thereof and has a smaller diameter than the base portion 37. 38 and an upper end portion 39 which is welded to the upper surface of the convex portion 38 and has the smallest radial dimension are overlapped with their centers aligned with each other, and have an arc portion of approximately 180 degrees.

The guide body G is fixed to the straddle arm 10 through holes 40 formed in the upper end portion 39 with through bolts 42 tightened from the upper surface of the straddle arm 10.

Slides 24A... 24E are adhered to the upper and lower surfaces of the base 37 of the guide G and the inner and outer surfaces of the projection 38, respectively.
Also, the sliding with the bracket 13 is smoothed.

The guide G is slidably mounted on the guide 3.
6B can fit. The guided body 36B has a projecting portion that can be slidably inserted into gaps A that can be formed on the inner surfaces of the base 37, the convex portion 38, and the upper end 39 of the guiding body G, and has a neck portion on the lower surface thereof. 36A is fixed to the upper surface of the horizontal portion 13b of the bracket 13. The diameter of the neck 36A is substantially the same as the inner diameter of the base 37.

The bracket 13 is provided with
The road wheel 1 has a hanging portion 13a that hangs downward, and a bearing shaft 14 that is welded to the hanging portion 13a is supported by a bearing.
2L is rotatably supported.

Reference numeral 20 denotes an arcuate spur gear having a tooth surface formed on an outer peripheral edge, an inner peripheral edge being cut out so as to coincide with an outer peripheral edge and an upper surface of the base 37, and a bracket 13 provided with a bolt 23. Are fixed to holes 41 formed in the horizontal portion 13b.

Accordingly, the guide body G is covered from both sides by the guided body 36B from the outside of the vehicle body and by the spur gear 20 from the center side of the vehicle body. In the spur gear 20, a drive gear 19 meshing with the spur gear 20 is housed and disposed in the straddle arm 10 on the vehicle body center side with respect to the spur gear 20.

In this embodiment, as a means for rotating the drive gear 19, the drive gear 19 is provided in parallel with the steering shaft 16 as in the prior art, is rotatably supported by the boss 22, and has a timing pulley 18 at its upper end. Are fixed, the pinion 33, the one-stage reduction gear 31,
The rotary shaft 29 is rotated via an idle gear 32 and a two-stage reduction gear 30 which are coaxially formed with the drive shaft 17 via a timing pulley 25 and a timing belt 35.
An example in which is rotated.

Now, as shown in FIG. 5, when the steering motor 34L is driven to rotate the timing belt 35 as shown in the figure, the bracket 13 guided by the guide body G and pivotally supporting the load wheel 12L is moved along the axis. 16
Can perform a circular motion around the center. At this time, the slides 24A to 24E are attached around the guide body G as described above, so that the bracket 13 can slide smoothly. FIG. 5 shows the state of the maximum steering angle.
When such a state is detected by the encoder 28, the steering motor 34L may be stopped, or another mechanical stopper or the like may be provided to limit the steering angle. .

Further, the center line of the road wheel 12L and the turning center of the steering shaft 16 can be eccentric by a distance e which is a so-called kingpin offset. This means that, as shown in FIG.
When the vehicle is driven right beside, if the steering center is positioned at the center of the road wheel 12L, the wheel base becomes L. However, by providing the eccentric distance e as described above, L + 2e
This is because the wheel base can be secured.
In addition, when the forklift is stationary, the road wheel 12L is steered, that is, during so-called stationary operation, the friction between the road wheel 12L and the ground can be reduced and the rolling can be performed, so that the driving torque during steering can be reduced. Because you get it.

The guide member G and the guided member 36B are
In this example, the center of each arc is the axis 16, and the road wheel 12L is exemplified to be steered about the axis 16. However, the diameter of the arc of the guide body G and the guided body 36B is determined. By making various changes, the above-described eccentric distance e can be set freely and can be made large. The other road wheel 12R also has the same configuration, and is configured symmetrically with respect to the vehicle body center line of the forklift.

[0028]

According to the present invention, as a result of employing the above configuration,
The virtual steering center of the road wheel can be provided on the left and right outer sides of the vehicle body without actually providing the steering axis of the road wheel. This eliminates the need for a bearing that supports the steering shaft, a housing that supports the bearing, and the like, so that the space in the straddle arm can be significantly reduced, and the width of the straddle arm can be reduced.

Also, since the above-mentioned eccentric distance e can be set large without increasing the width of the straddle arm, a sufficient wheel base can be secured even when the vehicle is running sideways, and running stability can be improved. The effect that it is excellent in the improvement of the performance and the riding comfort can be achieved.

[Brief description of the drawings]

FIG. 1 is a perspective view of the present invention.

FIG. 2 is a front view of the present invention.

FIG. 3 is a side view of the present invention.

FIG. 4 is a plan view of the present invention.

FIG. 5 is a plan view of the present invention.

FIG. 6 is a plan view for explaining a wheel base.

FIG. 7 is a side view of a conventional reach-type forklift.

FIG. 8 is a front view for explaining a conventional road wheel steering mechanism.

FIG. 9 is a plan view illustrating a conventional road wheel steering mechanism.

FIG. 10 is a side view illustrating a conventional road wheel steering mechanism.

[Explanation of symbols]

 G Guide 10 Straddle arm 12L Road wheel 12R Road wheel 13 Bracket 13a Hanging part 13b Horizontal part 14 Bearing shaft 16 Steering shaft 19 Drive gear 20 Spur gear 36A Neck 36B Guided body 37 Base 38 Convex part 39 Upper end

Claims (1)

(57) [Claims] An arcuate guide body whose center can be located near the distal end of each of the left and right straddle arms and located at an outer position in the width direction of the vehicle body is fixed to each of the left and right straddle arms. A guided body that can be slidably fitted to the guide body is fixed to the upper surface, and the load wheel is turned from the center of the vehicle body and the center in the width direction of the load wheel at a predetermined distance from the center of the guide body. A bracket having a hanging portion movably supported, and a gear cut in an arc shape in the bracket and having a gear with the arc side directed toward the center of the vehicle body fixed to cover the guide body, and attached to the arc gear. A load wheel in a reach-type forklift, wherein a meshing drive gear is housed and arranged in each of the left and right straddle arms at a position closer to the vehicle body than the arc-shaped gear. Steering gear.