JPH04345500A - Load detecting device of forklift - Google Patents

Abstract

PURPOSE:To provide a load detecting (device which can protect a stain gauge (a load detector) adequately from a shock in a cargo handling work of a forklift, or a vibration in its running, and can weigh the cargo only at an optimum height of the fork. CONSTITUTION:This load detecting device is a device in which a fork 6 is supported on a fixed plate 4 fixed at the front side of a lift bracket 3, and a movable plate 5 provided vertical to the fixed plate in the condition to displace relatively, and by detecting the relative displacement of the fixed plate 4 and the movable plate 5, the weight of a cargo loaded to the above fork 6 can be detected. A cargo holder weight detecting means dog 20 to detect that the height of the fork 6 is at the upper side from the ground and within a preset optional scope, and a locking means to prevent the relative displacement of the movable plate 5 and the fixed plate 4 are provided, and the lock means is released only when the height of the fork is within the above optional scope.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] The present invention relates to a load detection device for a forklift truck, and in particular to a device that suitably protects the load detection device from shocks, vibrations during driving, etc., and can perform weighing only at an optimal height. Regarding.

0002

2. Description of the Related Art In frozen and refrigerated warehouses, storage charges, etc. are calculated based on the weight of stored cargo. Furthermore, since the transaction price is often calculated based on the weight, it is necessary to know the weight of the cargo on a pallet basis. However, when transporting cargo from a truck using a forklift, if the weight of the cargo is measured using a weighing scale each time, there is a problem in that the transport process takes a long time.

[0003] Conventionally, therefore, a device has been proposed that can measure the weight of a load loaded on a fork by detecting the hydraulic pressure acting on the lift cylinder of a forklift at the same time as the load is being transported. However, such a configuration causes measurement errors. extremely large,
Since it is not practical, in recent years, methods have been proposed that use strain meters to improve measurement accuracy. For example, as shown in FIGS. 3 to 5, the load amount detection device 12 includes a movable plate 5 on which the fork 6 of the forklift 1 is supported, and a fixed plate 4 fixed to a lift bracket 3 that moves the mast 2 up and down. The movable plate 5 and the fixed plate 4 are elastically connected to each other, and the relative displacement in the vertical direction between the movable plate 5 and the fixed plate 4 is detected by a strain gauge 10.

The lift bracket 3 has rollers 11 on its upper and lower sides, and is connected to one end of a chain that is moved up and down by a lift cylinder (not shown) to move up and down within the mast 2. Finger bars 3A, 3B are welded to the top and bottom, and the finger bars 3A,
A fixed plate 4 is engaged with 3B.

The fixed plate 4 is elastically connected to the movable plate 5 via leaf springs 7, . The structure is such that the amount of directional displacement is minute. Pair of left and right forks 6
, 6 are engaged with upper and lower finger bars 5A and 5B that are welded to the upper and lower front surfaces of the movable plate 5.

[0006] Furthermore, from the fixed plate 4 and the movable plate 5,
Brackets 9A and 9B are formed above and below, and the strain gauge 10 is held between them by bolts or the like. Therefore, when the load W is placed on the fork 6, the movable plate 5 descends by a small amount relative to the fixed plate 4, and as a result of this action, the strain gauge 10 is elastically deformed under the tensile load. This elastic deformation is measured by strain meter 1
The weight of the load W is displayed on the display 13 provided at the driver's seat of the forklift 1 by detecting the change in electrical resistance of 0 and performing predetermined processing.

[0007]

However, when a load W is placed on the fork 6 of the forklift 1 and the fork is lowered from a high place to the lowest position, the impact of the fork 6 colliding with the ground occurs. There is a problem in that this is transmitted to the strain meter 10 and causes a failure. In addition to this, the vibrations of the forklift 1 while it is running are always transmitted to the strain gauge 10, which is not preferable as described above. In addition, if the fork height during measurement differs each time, a measurement error will occur depending on the fork height.
There is also the problem that it is not possible to accurately weigh the load. The present invention was devised in view of the above-mentioned problems, and its purpose is to suitably protect strain gauges from shocks during loading and unloading operations of a forklift, vibrations during traveling, and moreover, only at the optimum fork height. An object of the present invention is to provide a load detection device capable of weighing a load.

[0008]

[Means for Solving the Problems] The present invention provides a lift bracket that is movable up and down with respect to a mast of a forklift, a fixed plate fixed to the front surface of the lift bracket, and a fixed plate fixed to the front side of the fixed plate. A load support is supported on a movable plate that is provided so as to be relatively displaceable in a direction perpendicular to the plate, and the load is loaded on the load support by detecting the relative displacement between the fixed plate and the movable plate. A device for detecting the weight of a load supporter, wherein the height of the load support is above the ground;
In addition, a load support height detecting means for detecting that the height of the load support is within a predetermined arbitrary range, and a locking means for preventing the movable plate from displacing relative to the fixed plate are provided. The support height detecting means is configured to release the locking means only when the height of the load support is within the arbitrary range.

[0009]

[Operation] According to the present invention, only when the forklift 1 inserts the fork 6 into the pallet and lifts it up to a predetermined height, the fixed plate 4 and the movable plate 5 are elastically connected, and the load is It becomes possible to detect the weight of On the other hand, since the fixed plate 4 and the movable plate 5 are mechanically fixed, for example, the fork 6
Even if it hits the ground at the lowest position, the impact will not be transmitted to the strain gauge 10.

0010

[Embodiment] An embodiment of the present invention will be described below with reference to FIG. In the figure, the same reference numerals are given to the same parts as in the prior art. The load detecting device 12 has the same configuration as the conventional one, and although the explanation is omitted here, in the present invention, the load detecting device 12 is a load detecting device that detects that the height of the fork 6 is within an arbitrary range from the ground. As tool height detection means, a dog 20 is fixed to the mast 2, and the dog 2
A lever 15 that swings when it comes into contact with a lever 15 is illustrated as an example. Further, as a locking means capable of preventing the movable plate 5 from being displaced relative to the fixed plate 4, a slide pin 16 is inserted into a hole 19 formed in the movable plate 5.

The dog 20 is fixed to one side of the mast 2 over a predetermined length, and both ends thereof are cut out in a tapered shape. Further, a support piece 1 is provided on the back side of the fixed plate 4.
7 is fixed to the support piece 17, and a substantially middle portion of a lever 15 having a roller 14 at its tip is rotatably supported by the support piece 17. Furthermore, a slide pin 16 is loosely fitted and supported at one end of the lever 15. Note that the mast 2 indicates a fixed mast in this example.

The slide pin 16 passes through the fixed plate 4, and its tip is inserted into a hole 19 formed in the movable plate 5. Further, a flange 16A is formed near the tip of the slide pin 16, and a spring 18 is elastically inserted between the flange 16A and the fixed plate 4, so as to always urge the slide pin 16 toward the movable plate 5. configured. Note that when the slide pin 16 is inserted into the hole 19, care is taken to prevent relative displacement between the fixed plate 4 and the movable plate 5.

However, when the fork 6 is at the lowest position, the fixed plate 4 and the movable plate 5 are fixed by a slide pin 16, as shown in FIG. Therefore, even if the fork 6 collides with the ground, the impact is not transmitted to the strain gauge 10, and furthermore, the load cannot be weighed. Next, when the fork 6 is raised,
As shown in FIG.
The slide pin 1 comes into contact with the dog 20 provided on the
6 slides to the left in the figure against the spring 18, and the fixed plate 4 and the movable plate 5 are elastically supported by the leaf spring 7, and their relative displacement is measured by the strain gauge 10. It becomes possible.

When the fork 6 is further raised from the above state, the roller 14 of the lever 15 separates from the dog 20, and the slide pin 16 is inserted into the hole 19 by the restoring force of the spring 18, and the strain gauge 10 is inserted into the slide pin 16. The elastic deformation is removed and the fixed plate 4 and movable plate 5 are fixed again. Therefore, in this state, the vibration while the forklift is running is
It is not transmitted to the strain gauge 10, and furthermore, the load cannot be measured.

Although one embodiment of the present invention has been described in detail above, the range of fork heights at which loads can be weighed can be determined by adjusting the mounting position and length of the dog 20 in various ways depending on the forklift used. It is sufficient to set the range within which the error is the smallest. In addition, in this example, the height of the fork is detected using the dog 20 and the lever 15, but in addition to this, for example, a limit switch may be used to detect the height, or a magnetic tape may be attached to the mast side to detect the height of the fork. A similar function can be obtained by using a magnetic sensor provided on the side. When detecting the fork height electrically as described above, the slide pin shown in this example may be configured to be driven using an actuator (for example, an electric cylinder or the like). Further, in the above embodiment, a pair of left and right forks are illustrated as load supporting devices, but various attachment devices used in forklifts may be attached without departing from the gist of the present invention. It can also be suitably employed.

[0016]

[Effects of the Invention] As a result of adopting the above configuration, the present invention has the following advantages:
Only when the forklift lifts the load to a predetermined height range, the fixed plate and the movable plate are elastically connected, making it possible to weigh the load. Since the plate and the movable plate are in a mechanically fixed relationship, it is possible to prevent the strain gauge from being destroyed if the fork collides with the ground at its lowest position or by vibrations while driving. can. Furthermore, since the height of the fork when weighing the load is always within a certain range, variations in weighing errors can be prevented and accurate weighing can be performed.

[Brief explanation of drawings]

FIG. 1 is a side view showing an embodiment of the present invention.

FIG. 2 is a side view showing an embodiment of the present invention.

FIG. 3 is a side view of a forklift truck equipped with a conventional load detection device.

FIG. 4 is a side view showing a conventional load detection device.

FIG. 5 is a plan view showing a conventional load detection device.

[Explanation of symbols]

1 Forklift 2 Mast 3 Lift bracket 4 Fixed plate 5 Movable plate 6 Fork 7. Leaf spring 8 Reinforcement plate 9A Bracket 9B Bracket 10 Strain meter 12 Load detection device 15 Lever 16 Slide pin 17 Bearing piece 18 Spring 19 hole 20 Dog

Claims (1)

[Claims] 1. A lift bracket provided to be movable up and down with respect to the mast of a forklift, a fixed plate fixed to the front surface of the lift bracket, and a fixed plate disposed in front of the fixed plate relative to the fixed plate in a vertical direction. A device for detecting the weight of a load loaded on the load support by supporting a load support on a movable plate provided in a movable state and detecting relative displacement between the fixed plate and the movable plate. load support height detection means for detecting that the height of the load support is above the ground and within a predetermined arbitrary range; The present invention is characterized in that a locking means capable of preventing the load supporting device from being displaced is provided, and the locking device is released only when the height of the load supporting device is within the arbitrary range as determined by the load supporting device height detecting device. Forklift load detection device.