JPH0721509Y2 - 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 pivot 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 telescopic 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, a load is applied to the telescopic boom 3 of such an aerial work vehicle in the falling direction due to the weight of the telescopic boom 3, the weight of the workbench 5, and the weight of the operator and equipment on the workbench 5. This load varies depending on 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 load increases. Therefore, when this load reaches a permissible value set according to the hoisting angle of the telescopic boom 3, the amount of extension, the tension width of the outrigger 8, etc., an alarm is issued or the telescopic boom that increases the load any further is issued. A safety device that regulates the operation of 3 is used.

Conventionally, this load is detected by detecting the axial force acting on the undulating cylinder 4. Specifically, for example, a load cell is incorporated in a pin 4a that pivotally supports the hoisting cylinder 4 to the swivel base 2, the axial force is detected from the bending load applied to the load cell, and the detected value is applied to the telescopic boom 3. The magnitude of the load was estimated by converting it into a moment around the pivot point.

However, when the leveling device having the above-described configuration is used, the telescopic boom 3 is also supported by the lower leveling cylinder 7, and the axial force of the hoisting cylinder 4 alone provides a moment around the pivot base point of the boom 3. There is a problem that the detection of is inaccurate.

Therefore, in Japanese Utility Model Publication No. 1-14640, the axial force of the lower leveling cylinder 7 is detected separately from the hoisting cylinder 7, and the moment about the pivot axis of the boom 3, that is,
It is disclosed that the load of the telescopic boom 3 is detected.

(Problems to be Solved by the Invention) If the axial force acting on the lower leveling cylinder 7 and the axial force acting on the undulating cylinder 4 are detected in this way to obtain the load, the load can be accurately detected. It is possible, but the load cell for detecting the axial force is the undulating cylinder 4.
And the leveling cylinder 7 are required, and there is a problem that the load detecting device is complicated in structure and expensive. Further, it is necessary to add the detected two axial forces to calculate the load, which causes a problem that the load calculation process is likely to be complicated.

The present invention has been made in view of such a problem. 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 load. 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 detection device of the present invention, the pivot point of the undulating cylinder to the vehicle body and the pivot point of the lower leveling cylinder to the vehicle body are the same. Position, and at this position, one pin member pivotally supports both the undulating cylinder and the lower leveling cylinder on the vehicle body,
Further, the pin member is provided with a load detector, and the load acting on the boom is detected by the load detector.

(Operation) In the case of the moment detecting device having the above configuration, the axial force acting on the undulating cylinder and the axial force acting on the lower leveling cylinder are received by the pin member. For this reason,
The resultant force of both axial forces 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 moment detecting 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 proximal boom 3a and a distal boom 3b is pivotally attached to the swivel base 2 so that the telescopic boom 3 can swing 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.

The hoisting cylinder 14 for hoisting the telescopic boom 3 has a piston rod whose distal end is supported by the pin 14a at the base end boom 3a.
While being pivotally supported by an undulating bracket 13 joined to the lower surface of the cylinder tube, the lower end of the cylinder tube is pivotally supported by a pin member 11 on a cylinder support member 21 attached to the swivel base 2, and the swivel base 3 and the base end boom 3a. It is arranged in between.

In addition, the lower leveling cylinder 17 includes the undulating bracket where the tip of the piston rod is on the lower surface of the proximal boom 3a.
The cylinder tube is pivotally supported by a leveling bracket 16 joined to the base end side of the cylinder 13, and the cylinder tube is supported on the cylinder support member 21 via a leg member 18 extending from the cylinder tube to the lower end side in the axial direction. It is pivotally supported by the pin member 11 at the same position as the pivot point of the lower end of the cylinder tube, and is arranged between the swivel base 2 and the base boom 3a.

The pivot structure of the pin member 11 is shown in detail in FIG.

The cylinder support member 21 attached to the swivel base 2 has a pair of support portions 21a, 21a, and insertion holes 21b, 21b are formed in the support portions 21a, 21a.

At the lower end of the cylinder tube of the undulating cylinder 14, the pivot portion 14b is attached.
Is provided, and an insertion hole (not shown) corresponding to the insertion hole 21b is formed in the pivot portion 14b. Further, a pair of leg members 18, 18 extending toward the lower end side in the axial direction are attached to the side portion of the cylinder tube of the lower leveling cylinder 17. The middle portion of each leg member 18, 18 is
The spacing between the 18 is formed to be wider than the diameter of the cylinder tube of the undulating cylinder 14, which allows the leg members to
18 and 18 can be positioned so as to sandwich the cylinder tube of the undulating cylinder 14. further,
At the base ends of the leg members 18, 18, a pivot portion 14b of the undulating cylinder 14 is provided.
The space is narrowed so as to sandwich it, and is formed so that it can be inserted between the support portions 21a of the cylinder support member 21.
Insertion holes 18a, 18a (only the insertion hole 18a of the leg member 18 on the procedure side is shown) are also formed at the base ends of the leg members 18, 18.

For this reason, as shown in the figure, with the pivotal support portion 14b of the undulating cylinder 14 inserted between the base end portions of the leg members 18, 18 of the lower leveling cylinder 17, these are supported by the support portion of the cylinder support member 21.
By inserting the pin member 11 into the cylinder supporting member 21 at the same position by inserting the pin member 11 with the insertion holes (18a, 21b, etc.) inserted between the cylinder supporting member 21a and 21a. Can support.

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 telescopic boom 3 is lifted up and down, the lower leveling cylinder 17 is extended, but the upper leveling cylinder 6 is contracted according to this extension, and the workbench 5 is held in a horizontal state. To be done.

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. To detect this moment, a load cell is arranged on the pin member 11 that pivotally supports the cylinder support member 21 while connecting the undulating cylinder 14 and the lower leveling cylinder 17, and the load cell causes the undulating cylinder 14 and the lower leveling cylinder 17 to be connected. The resultant force of the acting axial forces is detected.

The falling direction moment acting on the telescopic boom 3 is calculated by using the resultant force of the axial forces detected by the load cell. In this case, the direction of the axial force acting on the undulating cylinder 14 and the lower leveling cylinder 17 are calculated. The direction of the axial force differs because the axial directions of both cylinders 14 and 17 are different.
Specifically, as shown in FIG. 3, when the position of the pin member 11 is indicated by a point p, the axial force of the undulating cylinder 14 acting on the pin member 11 is indicated by the vector A, and the axial force of the lower leveling cylinder 17 is indicated. The force is indicated by the vector 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 member 11 becomes a vector E (vector going from the point p to the point r) which 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. To do.

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. Effect of the Invention As described above, according to the present invention, the pivoting of the undulating cylinder to the vehicle body and the pivoting of the lower leveling cylinder to the vehicle body are performed by one pin member at the same position, and the pin member is provided. The load detector (load cell) is configured to detect the resultant force of the axial force acting on the undulating cylinder and the axial force acting on the lower leveling cylinder, which is an element for calculating the load acting on the boom. Therefore, in the load detecting device for detecting the load acting on the boom, only one of the load detectors is required as a detector, which simplifies the structure of the device and reduces the cost. be able to.

[Brief description of drawings]

FIG. 1 is a front view showing an aerial work vehicle equipped with a moment detecting device according to the present invention, and FIG. 2 is a view showing a connection between a hoisting cylinder, a lower leveling cylinder, a cylinder support member, and a pivot portion in the aerial work vehicle. FIG. 3 is a vector diagram showing a force acting on this connecting portion, and FIG. 4 is a front view showing a conventional aerial work vehicle. 1 ... Body 3, 3 Telescopic boom 4,14 ... Release cylinder 5 ... Work table 6,7,17 ... Leveling cylinder 11 ... Pin member, 21 ... Cylinder support member

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 leveling cylinder and the upper leveling cylinder that expands and contracts according to the expansion and contraction of the lower leveling cylinder due to the ups and downs of the ups and downs boom, and that keeps the work table always horizontal. In a vehicle, a device for detecting a load acting on the boom, comprising: a pivot point of the undulating cylinder to the vehicle body; The pivoting point of the leveling cylinder with respect to the vehicle body is arranged at the same position, and at this position, both the undulating cylinder and the lower leveling cylinder are pivotally supported on the vehicle body by one pin member, and load detection is performed on this pin member. A load detection device for a boom work vehicle, which is provided with a container.