JPH05800A - Load sensign mechanism of fork lift truck - Google Patents

Abstract

PURPOSE:To output an indication or an alarm, etc., if necessary by sensing a loading state of the cargo placed on the forks of a fork lift truck. CONSTITUTION:The screw shaft 41 of a screw travelling mechanism 4 for expanding and contracting a mast 3 is supported by a frame 1 through a vertical load sensing mechanism 21, and the vertical load sensing mechanism 21 detects the load by means of a strain sensor 26 provided on a detecting member 24, and a strain sensor for detecting a moment load acted upon right and left forks 6 is attached to the holder 5 mounted elevatably on the mast 3.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a forklift truck,
In particular, the present invention relates to a load detection mechanism that detects a vertical load applied to the entire fork and a moment load applied to the left and right forks.

[0002]

2. Description of the Related Art As a conventional forklift, a fork is supported on a mast forming a part of a frame so that the fork can move up and down.
The fork is used to lift the luggage to a predetermined height.

[0003]

By the way, in a forklift, not only the load applied to the entire forklift but also the load may be dropped during transportation when the load is unevenly placed on the left and right forks. Therefore, it is necessary to detect whether the load is unevenly placed on the left and right forks and issue a warning, but in the conventional forklift, the operator exclusively checks the load loading state. Just checking with his own eyes often causes the forklift to fall.

[0004]

In order to solve the above-mentioned problems, the present invention is suitable for a load sensor for detecting two vertical loads and two load sensors for detecting moment loads acting on the left and right forks. It was installed in a different place.

[0005]

The load applied to the left and right forks as well as the load applied to the entire lift is individually detected, so that the load on the fork is unsuitable, for example, when the load is loaded only on the tip of the fork. A warning can be issued by detecting a case where the sheets are loaded in a skewed manner.

[0006]

Embodiments of the present invention will be described below with reference to the accompanying drawings. Here, FIG. 1 is a side view of a forklift to which the load detecting mechanism according to the present invention is applied, FIG. 2 is a sectional view of a mast portion of the forklift seen from the front, and FIG. 3 is an enlarged vertical load detecting portion of the forklift. A sectional view, FIG. 4 is a side sectional view of a holding body of the forklift, and FIG. 5 is a graph used for explaining the operation of the load detecting mechanism.

The forklift has a frame 1 and an engine 2
Is mounted, and two masts 3 on the left and right (in the direction perpendicular to the paper surface in FIG. 1) are erected on the front end of the frame 1.
A screwing mechanism 4 is provided inside, and the screwing mechanism 4 holds the holder 5
Is moved up and down along the mast 3, and a fork 6 is foldably attached to the holder 5.

A foot portion 7 extends forward from the lower end portion of the frame 1. This foot portion 7 has a front wheel 8 at its tip end, and a base end portion thereof is rotatably supported by a shaft 9, and an auxiliary wheel 10 which comes into contact with the floor surface when the foot portion 7 is folded upward at this base end portion. Is attached.

A drive wheel 11 which is rotated by the engine 2 is provided at the rear portion of the frame 1.
1 to be steered by the handle 12, and further as shown in FIG.
As shown in FIG. 1, a hydraulic motor 13 that is rotated by the engine 2 is attached to the center of the frame 1.
The rotational driving force of No. 3 is distributed to the left and right drive shafts 15 and 15 via the helical gear 14, and the rotation of the drive shaft 15 is transmitted to the screw advance mechanism 4 via the helical gear 16.

The mast 3 includes an outer strut 31 and an inner strut 32.
The inner support column 32 is partially held in the outer support column 31 via bearings so as to be able to move up and down, and the other part is a guide rail 34, and a cross is provided between the upper ends of the left and right inner support columns 32. The plate 35 is installed. The screwing mechanism 4 is composed of a screw shaft 41, a screw pipe 42, and a nut member 43.

The screw shaft 41 of the screwing mechanism 4
The lower end of is supported rotatably on the frame 1 via a vertical load detection mechanism 21. This vertical load detection mechanism 21
As shown in FIG. 3, the bearing case 23 fitted to the outer peripheral surface of the screw shaft 41 is housed in the tubular body 22 fixed to the frame 1, and the tubular detection member 24 is placed on the bearing case 23. A bearing 25 is disposed on the detection member 24, and one member 2 of the bearing 25 is disposed.
5a is mounted on the detection member 24 and is vertically movably mounted on the inner peripheral surface of the tubular body 22, and the other member 25b is fitted on the outer peripheral surface of the screw shaft 41. And
A strain sensor 26 as a load sensor for detecting a vertical load is attached to the outer peripheral surface of the detection member 24. The vertical load detection mechanism 21 is provided near the base end of each screwing mechanism 4 of the left and right masts 3.

As shown in FIG. 4, a long hole 51 is formed in the holding body 5, and a pin 62 provided at a base end portion 61 of the fork 6 is engaged in the long hole 51 to hold the holding body. A fork 6 is rotatably supported on the fork 5.

Further, the upper end of a leaf spring 54 is fixed to the holder 5 with pins 52 and 53, and a strain sensor 27 which is a load sensor for detecting a moment load applied to the fork is attached to the leaf spring 54. . The leaf springs 54 are provided on the left and right, and the strain sensor 27 is attached to each leaf spring.
The moment load applied to the left and right forks is detected separately.

With the above construction, when the luggage is loaded on the left and right forks 6, the load is applied to the entire lift, whereby the screw shaft 41 of the screwing mechanism 4 is loaded.
Since the strain is generated in the detection member 24 of the vertical load detection mechanism 21 via the bearing 25 and the strain sensor 26 outputs a detection signal according to the strain amount of the detection member 24, the vertical load applied to the entire lift is Can be detected.

The fork 6 is also loaded by the load. This load causes the action pin 63 fixed to the fork 6 to abut against the leaf spring 54 as shown in FIG.
Cause distortion. Then, this strain is measured by the strain sensors 27 on the left and right.
Since the detection signal corresponding to the amount of strain is output, the moment load applied to the left and right forks 6 can be detected.

Therefore, based on these detection results, for example, on the display provided in the vicinity of the handle 12, as shown in FIG. The load ratio applied to the fork 6 is displayed. By the way, in the figure, the solid line indicates the distance to the point of action of the load, and the left and right frames indicate the load ratio.

As a result, the load is not placed on the tip of the fork 6 (in this embodiment, 35 from the base).
It is possible to judge the state of the luggage such as whether it is placed within 0 mm) or whether it is placed unevenly on one of the left and right forks 6, and a warning can be issued in such a state. .

[0018]

As described above, according to the present invention,
Since it is equipped with two load sensors that detect vertical loads and two load sensors that detect moment loads acting on the left and right forks, the loading state of the load can be detected accurately and quickly. A warning or the like can be issued accordingly.

[Brief description of drawings]

FIG. 1 is a side view of a forklift truck to which a load detection mechanism according to the present invention is applied.

FIG. 2 is a cross-sectional view of the mast portion of the forklift seen from the front.

FIG. 3 is an enlarged cross-sectional view of a vertical load detector of the forklift truck.

FIG. 4 is a side sectional view of a holding body of the forklift truck.

FIG. 5 is a graph for explaining the operation of the load detection mechanism.

[Explanation of symbols]

3 ... Mast, 4 ... Screw advancement mechanism, 5 ... Holding body, 6 ... Fork, 21 ... Vertical load detection mechanism, 24 ... Detection member, 26,
27 ... Strain sensor (load sensor).

Claims (2)

[Claims] 1. A forklift equipped with two left and right forks that can freely move up and down, the forklift detecting two load sensors for detecting a vertical load and a moment load acting on each of the left and right forks. A load detection mechanism for a forklift, which is equipped with individual load sensors. 2. A load sensor for detecting the vertical load is provided near a base end portion of a mast supporting a fork, and a load sensor for detecting the moment load is provided on a holder. Forklift load detection mechanism described.