JPH0721508Y2 - Boom work vehicle load detection device - Google Patents

Description

[Detailed Description of Device] a. Purpose of the Invention (Industrial field of application) The present invention relates to an aerial work vehicle in which a work platform is swingably mounted at the tip of at least a boom that can be raised and lowered, and more specifically, in this aerial work vehicle, The present invention relates to a load detection device that detects a load acting on a boom.

(Prior Art) In the aerial work vehicle described above, a leveling device that always holds the work table horizontally is used. An example of an aerial work vehicle equipped with this leveling device is shown in FIG. This aerial work vehicle has a swivel base 2 that can swivel on a vehicle body 1, and a telescopic boom 3 is attached to the swivel base 2 so as to be able to rise and fall.
The telescopic boom 3 is composed of a base end boom 3a pivotally supported by the swivel base 2 by a pin 2a and a tip boom 3b which is extendable and retractable with respect to the base end boom 3a.
A workbench 5 is attached so as to be vertically swingable by 5a. Outriggers 8 are provided at four positions on the front, rear, left, and right of the vehicle body 1 to extend and support the vehicle body 1 during work.

A hoisting cylinder 4 is provided between the vehicle body 1 and the base boom 3a, and the hoisting operation of the telescopic boom 3 is performed by expanding and contracting the hoisting cylinder 4. Further, a telescopic cylinder (not shown) is arranged inside the telescopic boom 3, and the telescopic operation of the tip boom 3b is performed by the telescopic cylinder extending and contracting. An upper leveling cylinder 6 is arranged between the tip boom 3b and the workbench 5 as shown in the drawing, and the swinging control of the workbench 5 in the vertical direction is performed according to the expansion and contraction of the upper leveling cylinder 6. .

This swing control is performed so that the posture of the workbench 5 is always kept horizontal, and the lower leveling cylinder 7 is arranged between the vehicle body 1 and the base end boom 3a, and the bottom of the upper leveling cylinder 6 is arranged. The side oil chamber communicates with the bottom oil chamber of the lower leveling cylinder 7, and the rod side oil chamber of the lower leveling cylinder 7 communicates with the rod side oil chamber of the upper leveling cylinder 6. Therefore, the undulating boom 3
When the lower leveling cylinder 7 is expanded and contracted by the up-and-down movement, the upper leveling cylinder 6 is expanded and contracted in the direction opposite to the lower leveling cylinder 7, whereby the posture of the workbench 5 is always kept horizontal. ing.

On the other hand, in such an aerial work vehicle, the overturning direction moment generated by the weight of the telescopic boom 3 and the workbench 5 and the weight of the operator and equipment on the workbench 5 is applied to the vehicle body 1.
This moment differs depending on the size of the weight, the hoisting angle of the telescopic boom 3, the extension amount, the tension width of the outrigger 8, etc., and there is a problem that the vehicle stability deteriorates when the moment increases. Therefore, when this moment reaches a permissible value set according to the hoisting angle of the telescopic boom 3, the extension amount, the tension width of the outrigger 8, etc., an alarm is issued or the boom 3 that further increases the moment is reached.
A safety device is used to regulate the operation of the.

Conventionally, this moment is detected by the undulating cylinder 4
It was carried out by detecting the axial load acting on. Specifically, for example, a load cell is incorporated in a pin 4a that pivotally supports the undulating cylinder 4 to the swivel base 2, and the axial load is detected from the bending load applied to the load cell.

However, when the leveling device configured as described above is used, the telescopic boom 3 is also supported by the lower leveling cylinder 7, and the axial load of the hoisting cylinder 4 alone causes the telescopic boom 3 to move around the base point of the boom 3. There is a problem that the detection of the moment becomes inaccurate.

Therefore, Japanese Utility Model Publication No. 1-14640 discloses that the axial load of the lower leveling cylinder 7 is also detected to detect the moment around the base point of the boom 3.

(Problems to be solved by the invention) If the load acting on the lower leveling cylinder 7 and the load acting on the undulating cylinder 4 are detected in this way to obtain the moment, the moment can be accurately detected. There are 2 load cells to detect the load
There is a problem in that it requires individual pieces, which leads to a complicated structure and high price. Furthermore, it is necessary to add the two detected loads to calculate the moment, and the moment calculation process tends to be complicated.

The present invention has been made in view of such a problem, and it is possible to detect the load including the load of the lower leveling cylinder with only one load detector (load cell), and to accurately calculate the moment. An object is to provide a load detection device for a boom work vehicle.

B. Configuration of the Invention (Means for Solving the Problems) In order to achieve such an object, in the load detecting device of the present invention, the pivot point of the undulating cylinder to the boom and the pivot point of the lower leveling cylinder to the boom are the same. Position, and at this position, the undulating cylinder, the lower leveling cylinder and the boom are connected by one pin member, and a load detector is provided on this pin member, and the load acting on the boom is provided by this load detector. It is configured to detect.

(Operation) In the case of the load detection device having the above configuration, the axial force (load) acting on the undulating cylinder and the axial force (load) acting on the lower leveling cylinder are received by the pin member. Therefore, the resultant force of both axial forces (loads) can be detected only by the load detector (load cell) provided on the pin member.

(Embodiment) Hereinafter, a preferred embodiment of the present invention will be described with reference to the drawings.

FIG. 1 shows an aerial work vehicle equipped with a load detection device according to the present invention. Since this aerial work vehicle is similar to the conventional aerial work vehicle shown in FIG. 4, the same parts as those in FIG.

A swivel base 2 is provided on the vehicle body 1, and a telescopic boom 3 composed of a base boom 3a and a tip boom 3b is movably arranged on the swivel base 2, and the tip of the tip boom 3b swings up and down. A workbench 5 is movably attached. An upper leveling cylinder 6 is arranged between the workbench 5 and the tip boom 3b. Outriggers 8 are arranged on the front, rear, left and right of the vehicle body 1. The above structure is the same as that of the aerial work vehicle shown in FIG.

In the hoisting cylinder 14 for hoisting the telescopic boom 3, the lower end of the cylinder tube is pivotally supported by the swivel base 2 by the pin 14a, and the tip end of the piston rod 14b is the base end boom 3a.
It is pivotally supported by a pin 11 on a bracket 13 joined to the lower surface of, and is disposed between the swivel base 2 and the base end boom 3a.
Further, in the lower leveling cylinder 17, the lower end of the cylinder tube is pivotally supported on the swivel base 2 by the pin 17a, and
The fork 17c at the tip of the piston rod 17b is the undulating cylinder.
Pin 1 at the same position as the tip of 14 piston rod 14b
It is pivotally supported by 1 and is arranged between the swivel base 2 and the base end boom 3a.

The connection structure by the pin 11 is shown in detail in FIG. The bracket 13 is composed of a pair of plate members, and each has an insertion hole 13a. Lower leveling cylinder 17
The tip of the piston rod 17b is divided into two parts to form a fork part 17c. The fork part 17c also has an insertion hole.
17d is formed. The tip 14c of the piston rod 14b of the undulating cylinder 14 is shaped to be inserted between the fork portions 17c, and an insertion hole (not shown) corresponding to the insertion hole 17d of the fork portion 17c is formed.

Therefore, as shown in the drawing, with the tip 14c of the piston rod 14b of the undulating cylinder 14 inserted between the fork portions 17c, this is inserted between the brackets 13 and the insertion holes 13a, 17
By inserting pin 11 through d, the tip ends of both piston rods 14b and 17b can be pivotally supported on bracket 13 at the same position.

Here, the lower leveling cylinder 17 and the upper leveling cylinder 6 are connected via two oil passages, and thus a leveling device for always holding the workbench 5 in a horizontal state is constructed. Specifically, one of the above two oil passages connects the bottom side oil chamber of the lower leveling cylinder 17 and the bottom side oil chamber of the upper leveling cylinder 6, and the remaining one of the two oil passages causes the upper leveling to be performed. The rod-side oil chamber of the cylinder 6 and the rod-side oil chamber of the lower leveling cylinder 17 communicate with each other. Therefore, for example, when the boom 3 is erected, the lower leveling cylinder 17 is extended, but the upper leveling cylinder 6 is contracted in accordance with the extension, and the workbench 5 is held in a horizontal state. .

The aerial work vehicle having the above-described configuration further includes a moment detection device that detects a falling direction moment acting on the vehicle body. In order to detect this moment, the hoisting cylinder 14, the lower leveling cylinder 17, and the bracket 13 of the boom 3
A load cell is arranged on a pin 11 that connects the and, and the axial force (load) acting on the undulating cylinder 14 and the lower leveling cylinder 17 by the load cell is detected.

The axial force detected by this load cell is used to calculate the falling direction moment acting on the vehicle body.In this case, the direction of the axial force acting on the undulating cylinder 14 and the direction of the axial force acting on the lower leveling cylinder 17 are calculated. And both cylinders
This is different because the axis directions of 14 and 17 are different. Specifically, as shown in FIG. 3, when the position of the pin 11 is indicated by a point p, the axial force acting on the undulating cylinder 14 is indicated by a vector A, and the axial force acting on the lower leveling cylinder 17 is a vector. Indicated by B. Therefore, the axial force detected by the load cell arranged on the pin 11 is the force indicated by the combined vector C of the two vectors A and B (the vector from the point p to the point q).

However, the load cell detects only the value of the vector C, and its direction cannot be detected. Therefore, in order to calculate the falling direction moment acting on the vehicle body 1, it is necessary to preset the direction of the vector C. However, the axial force acting on the hoisting cylinder 14 (vector A) and the axial force acting on the lower leveling cylinder 17 (vector B) change in accordance with the weight of the workbench 5, the boom hoisting angle, the boom extension amount, and the like. Therefore, there is a problem that the direction of the vector C also changes, and it is necessary to consider this problem.

First, with respect to changes in the undulation angle, changes in the axial direction of the undulation cylinder 14 and the lower leveling cylinder 17 with respect to the undulation angle change can be calculated.
If the direction of B is calculated, the direction of vector C can be calculated.

Next, in the case of a change in the loading weight of the workbench 5, the axial force acting on the undulating cylinder 14 (vector A) and the axial force acting on the lower leveling cylinder 17 (vector B) corresponding to this change are simultaneously produced. Since it changes proportionally, its direction hardly changes even if the magnitude of the resultant force (vector C) changes. Therefore, also in this case, there is no problem if the direction of the vector C is calculated in advance.

Consider a case where the extension amount of the boom 3 changes. In this case, since the load on the workbench 5 does not change, the axial force of the lower leveling cylinder 17 does not change, but only the axial force of the undulating cylinder 14 changes. For example, when the boom 3 is extended, the axial force of the undulating cylinder 14 increases, and the vector A changes to the vector D in FIG. Therefore, the force received by the pin 11 becomes a vector E (a vector going from the point p to the point r) that is a combination of the vector D and the vector B, and not only the magnitude of the vector C up to that point but also the direction thereof changes. .

However, the angle between the axis of the undulating cylinder 14 and the axis of the lower leveling cylinder 17 is quite acute, and
The axial force acting on the undulating cylinder 14 is the lower leveling cylinder.
Since it is considerably larger than the axial force acting on 17, the direction of the vector (vector C or E) indicating the resultant force is obtained even if the axial force acting on the undulating cylinder 14 changes a little, as can be seen from FIG. Does not change much. Therefore, even if the direction of the resultant force vector is set with respect to the extension amount of the typical boom 3 and the moment is calculated based on this direction, the error is small, and there is no practical problem. In addition,
The extension amount of the boom 3 may be detected, and the error in the direction of the vector C may be corrected based on the detected value. By doing so, the detection accuracy can be further improved.

As described above, although there is a possibility of a slight error, it is possible to detect the almost accurate fall direction moment acting on the vehicle body 1 in accordance with the hoisting angle and extension amount of the boom 3.

On the other hand, the limit value of the moment is set from the viewpoint of the stability of the vehicle body 1, corresponding to the tension width of the outrigger 8, the hoisting angle of the boom 3, the extension amount, and the like. Then, when the moment detected as described above reaches this limit value, the operation of the boom 3 that further increases the moment is restricted to maintain stability.

C. Advantageous Effects of Invention As described above, according to the present invention, the hoisting cylinder is pivotally attached to the boom and the lower leveling cylinder is pivotally attached to the boom by one pin member at the same position.
Since the load detected by the load detector (load cell) provided on the pin member is used to detect the moment acting on the boom work vehicle, the axial force (load) acting on the undulating cylinder and the lower leveling are detected. The resultant force of the axial force (load) acting on the cylinder can be detected only by the load detector provided on the pin member. Therefore, only one load detector is required for the load detecting device that detects the overturning moment acting on the vehicle body, and the structure thereof can be simplified and the cost of the device can be reduced.

[Brief description of drawings]

FIG. 1 is a front view showing an aerial work vehicle equipped with a load detection device according to the present invention, and FIG. 2 is a perspective view showing a connecting portion between a hoisting cylinder and a lower leveling cylinder and a boom 3 in the aerial work vehicle. FIG. 3 is a vector diagram showing the force acting on this connecting portion, and FIG. 4 is a front view showing a conventional aerial work vehicle. 1 ... Car body, 3 ... Telescopic boom 4,14 ... Ring boom, 5 ... Work platform 6,7,17 ... Leveling cylinder 11 ... Pin, 13 ... Bracket

Claims (1)

[Scope of utility model registration request] 1. A boom mounted at least on a vehicle body so as to be hoisted, a hoisting cylinder which is provided between the boom and the vehicle body to hoist the boom, and at least vertically swingable at a tip of the boom. A workbench attached to the workbench, an upper leveling cylinder arranged between the workbench and the boom, a lower leveling cylinder arranged between the boom and the vehicle body, and an oil chamber of both of these leveling cylinders. And a leveling device that has an oil passage that connects the upper and lower leveling cylinders according to the extension and contraction of the lower leveling cylinder due to the ups and downs of the ups and downs boom, and keeps the work table always horizontal. In a vehicle, a device for detecting a load acting on the boom, comprising: The pivot point of the lower leveling cylinder to the boom is arranged at the same position, and at this position, the undulating cylinder and the lower leveling cylinder are connected to the boom by one pin member, and the load detector is connected to this pin member. A load detection device for a boom work vehicle, comprising: