JP3147091B2 - Industrial vehicle tilt angle detector - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a tilt angle detecting device for an industrial vehicle in which a mast for supporting and lifting and lowering an attachment for cargo handling is tiltably provided, and the mast is tilted by operation of a tilt cylinder.

[0002]

2. Description of the Related Art In a forklift as an industrial vehicle of this type, a mast provided with an outer mast and an inner mast provided at a front portion of the vehicle supports a fork together with a lift bracket so as to be able to move up and down. The mast is expanded and contracted by the operation of the lift cylinder based on the operation of the lift lever, and the fork is raised and lowered accordingly.
Further, in order to facilitate the cargo handling operation and to improve the stability during traveling of the forklift, the mast is tilted forward or backward with respect to the vertical reference position by operating the tilt cylinder based on the operation of the tilt lever. .

[0003] In a forklift, when a load is loaded on the fork, the center of gravity moves forward, and when the lift of the fork is increased, the moment acting on the mast increases. When the mast is tilted forward with a load being loaded, the center of gravity moves forward, and the stability of the forklift in the front-rear direction deteriorates. In addition, if the rearward tilt angle is too large in the state where the load is large, the center of gravity is too close to the rear side, so that the front wheels tend to float and slip may occur. Therefore, conventionally, the forward tilt angle and the backward tilt angle of the mast are set to predetermined values.

[0004] When a load is placed at a high place in a cargo handling operation, it is necessary to tilt the mast forward by setting the fork to a high elevation. At this time, if the mast is tilted forward at a high forward tilt speed due to an erroneous operation or the like, load collapse or lifting of the rear wheels of the forklift (that is, unstable state in the longitudinal direction of the vehicle) occurs. Therefore,
The operator needs to carefully perform the forward leaning operation at a low speed by inching operation so that the mast does not lean forward too much, which is a great mental burden. In addition, in the conventional apparatus, the operation of tilting the mast by setting the fork to a high elevation required skill.

[0005] Further, in general, at the time of unloading or unloading work, the fork is parallel to the pallet on which the load is loaded,
That is, it is necessary to make the fork horizontal (the mast is vertical). However, it requires skill to accurately level the fork by manual operation. In addition, it is necessary to perform the tilt operation and the traveling and lift operations during the actual cargo handling work, which increases the burden on the operator.

In order to solve the above problem, it is conceivable that the supply of hydraulic oil to the cylinder is controlled by a solenoid valve instead of a manually operated valve, and forklifts which perform automatic level control are also known. The applicant of the present application has previously proposed a forklift that regulates and controls the forward inclination allowable angle of the mast to a predetermined value according to the weight and height of the load. It is necessary to detect the inclination (tilt angle) of the mast when performing automatic leveling control or when restricting and controlling the mast forward inclination allowable angle to a predetermined value according to the weight or lift of the load.

Conventionally, the tilt angle is detected by a rotary potentiometer mounted on a fixed support shaft that supports the tilt cylinder on a vehicle body frame. A lever is supported on the input shaft of the potentiometer so as to be integrally rotatable, and the tip of the lever is disposed so as to clamp a pin abutting on the tilt cylinder. Then, the lever rotates together with the tilt cylinder with the expansion and contraction of the piston rod of the tilt cylinder, and the potentiometer outputs a detection signal corresponding to the amount of rotation of the lever.

Japanese Utility Model Laid-Open Publication No. 63-100500 proposes a tilt cylinder stroke detecting device that detects the tilt cylinder stroke using a rotary potentiometer. As shown in FIG. 4, the detecting device is a cylinder body 52 of a tilt cylinder 51.
Rotary potentiometer 5 via a bracket 53
4 are installed. The potentiometer 54 has a shaft 56 of a link 55 rotatably mounted on the bracket 53.
, And a link 55 is connected via a link rod 59 to a bracket 58 protruding from the piston rod 57.

[0009]

However, in the vicinity of the bottom portion of the tilt cylinder, mud or water splashes from the road surface while the forklift is running, or paper that has absorbed moisture adheres to the use environment of a used paper trader. The environment is very bad. Therefore, since the potentiometer is also in the bad environment, it tends to break down, and it is necessary to frequently perform maintenance and inspection.

In the stroke detecting device disclosed in Japanese Utility Model Laid-Open Publication No. 63-100500, since the potentiometer 54 is attached to the cylinder body 52 of the tilt cylinder 51 via the bracket 53, it is attached to the bottom of the tilt cylinder. The environment is better than in the case.
However, the bracket 5 supporting the potentiometer 54
3 requires a relatively large space, and the cylinder body 5
If such a bracket is fixed to 2, the workability at the time of attaching a hose for supplying hydraulic pressure to the tilt cylinder 51 will be poor. Further, since the bracket 53 cannot be made too long due to the arrangement position of the tilt cylinder 51, the position of the potentiometer 54 cannot be too far from the cylinder body 52, and the potentiometer 5
The environment of No. 4 is not sufficiently improved. In addition, a part of the interlocking rod 59 always projects forward from the front protector, and there is a high possibility that a dropping object or the like collides with the interlocking rod 59 during work and the interlocking rod 59 is damaged.

The present invention has been made in view of the above problems, and an object of the present invention is to arrange a mounting position of a rotational displacement sensor for detecting a tilt angle at a position as far as possible from a bottom portion of a tilt cylinder. In addition, it is an object of the present invention to provide a tilt angle detecting device for an industrial vehicle having a large degree of freedom in a mounting position.

[0012]

In order to achieve the above object, according to the first aspect of the present invention, a mast for supporting and lifting / lowering an attachment for cargo handling is tiltably provided,
In an industrial vehicle in which the mast is tilted by the operation of the tilt cylinder, a rotation displacement sensor is fixed at a predetermined position above the tilt cylinder of the body frame, and a lever is connected to an input shaft of the rotation displacement sensor so as to be integrally rotatable. A part that rotates integrally with the cylinder and the lever,
It was connected via a ball joint to a link arranged to extend in a direction crossing the tilt cylinder.

[0013] In the invention described in claim 2, the rotational displacement sensor is a rotary potentiometer. According to a third aspect of the present invention, in the first or second aspect, the ball joint at one end of the link is fixed to a cylinder tube of a tilt cylinder.

According to a fourth aspect of the present invention, in the first aspect of the present invention, the vehicle body frame is a front protector, and the rotational displacement sensor is fixed to a rear side. I have.

According to a fifth aspect of the present invention, in the fourth aspect of the invention, the link is disposed so as to be substantially parallel to the front protector when the mast is disposed at a vertical position. .

According to the first aspect of the present invention, the tilt angle (tilt angle) of the mast for supporting and lifting and lowering the cargo handling attachment is fixed at a predetermined position above the tilt cylinder of the machine frame. Is detected by The tilt angle is detected by transmitting the rotation of the tilt cylinder via a link to a lever that is integrally rotatably connected to the input shaft of the rotational displacement sensor. Since the link is connected to the rotating portion via the ball joint, the rotation of the tilt cylinder is smoothly transmitted to the lever even when the rotating surface of the lever intersects with the rotating surface of the tilt cylinder.

According to the second aspect of the present invention, since the rotational displacement sensor is a rotary potentiometer, the size and cost are reduced. According to a third aspect of the present invention, in the first or second aspect of the present invention, since one end of the link is fixed to a cylinder tube of the tilt cylinder via a ball joint, rotation of the tilt cylinder is prevented. Directly transmitted to the lever.

According to a fourth aspect of the present invention, in the first aspect of the present invention, the rotational displacement sensor is fixed to a rear side of the front protector, so that the rotational displacement sensor can be used during cargo handling. Hard to collide with falling objects and obstacles.

According to a fifth aspect of the present invention, in the fourth aspect of the invention, the link is disposed so as to be substantially parallel to the front protector when the mast is disposed at a vertical position. The rotation of the tilt cylinder accompanying the tilting of the mast is efficiently transmitted to the lever via the link.

[0020]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to FIGS. As shown in FIG. 3, the body frame (machine frame) of the forklift 1
2 has a mast 3 at its front. Mast 3
Is composed of a pair of left and right outer masts 3a that are supported to be tiltable with respect to the body frame 2, and inner masts 3b that are mounted inside the masts so as to be able to move up and down. Both outer masts 3a
On the rear side, a lift cylinder 4 is fixed in parallel with the outer mast 3a, and the tip of the piston rod 4a is connected to the upper part of the inner mast 3b. A lift bracket 5 is provided inside the inner mast 3b so as to be able to move up and down along the inner mast 3b, and a fork 6 as a cargo handling attachment is attached to the lift bracket 5.

A base end of a tilt cylinder 7 is rotatably supported on both left and right sides of the body frame 2, and a distal end of a piston rod 7a is rotatably connected to an outer surface of the outer mast 3a. Then, the mast 3 is tilted by the expansion and contraction operation of the tilt cylinder 7.

A steering 9, a lift lever 10, a tilt lever 11 and the like are provided at the front of the cab 8. FIG. 3 shows both levers 10 and 11 in an overlapping state. The lift cylinder 4 is operated (expanded and contracted) by operating the lift lever 10, and the tilt cylinder 7 is operated (expanded and contracted) by operating the tilt lever 11.

Next, the support state of the tilt cylinder 7 and the mounting state of the tilt angle detecting device for detecting the tilt angle (tilt angle) of the mast will be described. As shown in FIG.
A front pillar 13 that constitutes the cab 8 is provided upright on a fender 12 provided at a front portion of the body frame 2. A front protector 14 is welded to the body frame 2 at a predetermined inclination angle between the left and right front pillars 13 to form a part of the body frame 2. Lift lever 1
0, the tilt lever 11 and the steering column are mounted on the back side of the front protector 14.

A support bracket 15 is erected on the fender 12 on the inner side rearward of the front pillar 13. A portion of the body frame 2 facing the support bracket 15 is formed in a shape corresponding to the support bracket 15. Then, the tilt cylinder 7 has a front side protruding forward from the front protector 14, and at a base end thereof,
It is rotatably supported on a support shaft 16 provided between the body frame 2 and the support bracket 15.

As shown in FIGS. 1 and 2, a rotary potentiometer 17 as a rotational displacement sensor constituting the tilt angle detecting device is located at a predetermined position above the tilt cylinder 7 on the rear side (back side) of the front protector 14. Fixed. The potentiometer 17 is provided with a pair of bolts 1 on a pair of support portions 18 fixed to the front protector 14 by welding.
9. A base end of a lever 20 is connected to the input shaft 17a of the potentiometer 17 so as to be integrally rotatable. Ball joint 21 at the tip of lever 20
a is fixed. The potentiometer 17 may be a contact sliding type such as a conductive plastic type or a winding type, or a non-contact type such as a magnetoresistive type.

Cylinder tube 7 of tilt cylinder 7
The seat 22 is fixed to the seat 22 by welding so as to protrude in the horizontal direction, and a ball joint 21b is screwed to the seat 22. The cylinder tube 7b and the lever 20 are connected to the ball joints 21a, 21b via rods 23 each having both ends fixed as links. The rod 23 extends in a direction intersecting with the tilt cylinder 7, and is disposed substantially parallel to the front protector 14 when the mast 3 is disposed at a vertical position.

Next, the operation of the device configured as described above will be described. When the tilt cylinder 7 is operated based on the tilting operation of the tilt lever 11 and the piston rod 7a is protruded, the mast 3 is tilted (rotated) forward. As the mast 3 tilts forward, the tilt cylinder 7 is rotated downward about the support shaft 16. Tilt lever 1
When the tilt cylinder 7 is operated based on the backward tilt operation 1 and the piston rod 7a is retracted, the mast 3 is tilted (rotated) rearward. As the mast 3 is tilted backward, the tilt cylinder 7 is rotated upward about the support shaft 16.

When the tilt cylinder 7 is rotated upward, the lever 20 is rotated upward via the rod 23, and when the tilt cylinder 7 is rotated downward, the lever 20 is rotated downward via the rod 23. Be moved. Since the rod 23 is connected to the lever 20 and the cylinder tube 7b via the ball joints 21a and 21b, even if the rotation surface of the tilt cylinder 7 and the rotation surface of the lever 20 intersect, the tilt The rotation of the cylinder 7 is smoothly transmitted to the lever 20. Then, a voltage corresponding to the amount of rotation of the lever 20 is output from the potentiometer 17.

This embodiment has the following effects. (1) Since the potentiometer 17 is fixed at a predetermined position above the tilt cylinder 7 of the vehicle body frame 2 and is disposed at a position distant from the bottom portion where the environment is poor, even if the maintenance and inspection cycle is long, the tilt The reliability of the detected angle value is improved.

(2) Input shaft 1 of potentiometer 17
A rod 23 that connects the lever 20 that is integrally rotatable with the cylinder 7a and a cylinder tube 7b of the tilt cylinder 7 is connected via ball joints 21a and 21b. Therefore, even if the fixed position of the potentiometer 17 is separated from the tilt cylinder 7 and the rotation surface of the lever 20 and the rotation surface of the tilt cylinder 7 are not parallel, the rotation of the tilt cylinder 7 is smoothly applied to the lever 20. As a result, the degree of freedom of the mounting position of the potentiometer 17 is increased.

(3) Since the rotary potentiometer 17 is used as the rotational displacement sensor, the size and cost are reduced as compared with the case where the absolute value of the tilt angle is detected using a rotary encoder.

(4) Since the rotational displacement sensor (potentiometer 17) is fixed to the front protector 14,
The space for the mounting position of the potentiometer 17 is large, and the degree of freedom of mounting is increased.

(5) Since the rotational displacement sensor (potentiometer 17) is fixed to the rear side (back side) of the front protector 14, falling objects and obstacles are unlikely to collide with the rotational displacement sensor during cargo handling.

(6) Since the rod 23 is disposed so as to be substantially parallel to the front protector 14 when the mast 3 is disposed in the vertical position, the rotation of the tilt cylinder 7 accompanying the tilting of the mast 3 Is efficiently transmitted to the lever 20 via the rod 23.

(7) Since the ball joint 21b is fixed to the seat 22 projecting horizontally with respect to the cylinder tube 7b, the rod 23 is disposed so as to be substantially parallel to the front protector 14. In conjunction with this, the rotation of the tilt cylinder 7 due to the tilting of the mast 3 is efficiently transmitted to the lever 20 via the rod 23.

The embodiment is not limited to the above, and may be embodied as follows, for example. The location where the other end of the rod 23 whose one end is connected to the lever 20 is not limited to the cylinder tube 7b, but may be any part that rotates integrally with the tilt cylinder 7. For example, a ball joint 21 connected to the protruding end of the support shaft 16 so that the support shaft 16 can rotate integrally with the tilt cylinder 7.
The rod 23 is connected to b. Further, the rod 23 may be connected to the mast 3 via a ball joint.

The rotational displacement sensor only needs to detect the amount of rotation, and other sensors such as a rotary encoder and a resolver may be used. ○ The fixed part of the rotational displacement sensor is the front protector 1
The front side (front side) of 4 or the front pillar 13 may be used.

In the state where the mast 3 is disposed in the vertical position, the rod 23 is not disposed so as to be substantially parallel to the front protector 14, and the front protector 14
May be arranged so as to extend in a direction intersecting with.

Instead of connecting the lever 20 directly to the input shaft 17a, the input shaft 17a is connected to the rotating shaft rotatably supported by the front protector 14 so as to be integrally rotatable, and the lever is connected to the rotating shaft. 20 may be connected so as to be integrally rotatable.

Attachment other than the fork 6 as a cargo handling attachment, for example, a roll clamp used for transporting roll paper, a block clamp used for transporting blocks or stacking work, or a coiled wire or coil such as a coil. Alternatively, the present invention may be applied to a forklift (industrial vehicle) equipped with a ram or the like used for transporting a cylindrical load.

The inventions (technical ideas) other than those described in the claims which can be grasped from the embodiment will be described below together with their effects. (1) In the invention described in claim 5, the ball joint is fixed to a seat protruding from the cylinder tube in a horizontal direction. In this case, the rotation of the tilt cylinder accompanying the tilting of the mast is efficiently transmitted to the lever via the link, in combination with the link being disposed substantially parallel to the front protector.

[0042]

As described in detail above, claims 1 to 5 are provided.
According to the invention described in (1), the mounting position of the rotational displacement sensor for detecting the tilt angle can be arranged as far as possible from the bottom of the tilt cylinder, and the degree of freedom of the mounting position is increased.

According to the second aspect of the present invention, the size and cost are reduced as compared with the case where the absolute value of the tilt angle is detected using a rotary encoder. According to the third aspect of the present invention, since one end of the link is fixed to the cylinder tube of the tilt cylinder via the ball joint, the rotation of the tilt cylinder is directly transmitted to the lever to change the length of the link. As a result, the degree of freedom of the mounting position of the potentiometer increases.

According to the fourth aspect of the present invention, since the rotational displacement sensor is fixed to the rear side of the front protector,
It is difficult for falling objects or obstacles to collide with the rotational displacement sensor during cargo handling.

According to the fifth aspect of the present invention, since the link is disposed so as to be substantially parallel to the front protector, the rotation of the tilt cylinder caused by the tilting of the mast is efficiently transmitted to the lever via the link. Is done.

[Brief description of the drawings]

FIG. 1 is a perspective view showing a relationship between a tilt cylinder and a sensor according to an embodiment.

2A is a schematic side view showing a relationship between a tilt cylinder and a sensor, and FIG. 2B is an enlarged view of a portion surrounded by a circle A in FIG.

FIG. 3 is a schematic side view of a forklift.

FIG. 4 is a front view showing a conventional tilt cylinder stroke detection device.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Forklift as an industrial vehicle, 2 ... Body frame, 3 ... Mast, 6 ... Fork as a cargo handling attachment, 7 ... Tilt cylinder, 14 ... Front protector, 17 ... Rotary potentiometer as a rotational displacement sensor, 17a ... Input shaft, 20 ... lever, 21a, 2
1b: ball joint, 23: rod as link.

──────────────────────────────────────────────────続 き Continuation of the front page (56) References Hira 9-47 (JP, U) (58) Field surveyed (Int. Cl. ⁷ , DB name) B66F 9/24

Claims (5)

(57) [Claims] 1. An industrial vehicle in which a mast for supporting and lifting and lowering an attachment for cargo handling is tiltably provided, and the mast is tilted by the operation of a tilt cylinder, wherein the industrial vehicle is rotated to a predetermined position above the tilt cylinder of a body frame. A sensor is fixed, a lever is connected to the input shaft of the rotational displacement sensor so as to be integrally rotatable, and a part that rotates integrally with the tilt cylinder and the lever are disposed so as to extend in a direction crossing the tilt cylinder. Tilt angle detecting device for an industrial vehicle connected to a linked link via a ball joint. 2. The industrial vehicle tilt angle detecting device according to claim 1, wherein the rotational displacement sensor is a rotary potentiometer. 3. The tilt angle detecting device for an industrial vehicle according to claim 1, wherein the ball joint at one end of the link is fixed to a cylinder tube of a tilt cylinder. 4. The tilt angle detecting device for an industrial vehicle according to claim 1, wherein the vehicle body frame is a front protector, and the rotational displacement sensor is fixed to a rear side. 5. The tilt angle detecting device for an industrial vehicle according to claim 4, wherein the link is disposed so as to be substantially parallel to the front protector when the mast is disposed at a vertical position.