JPH05321302A - Hydraulic shovel also useable as crane - Google Patents

Abstract

PURPOSE:To reduce the mounting cost of a safety device, such as a moment limiter and to improve the durability thereof, by a method wherein a cylinder pressure sensor is provided at a booms-cylinder and on the basis of signals from both an arm angle sensor and the cylinder pressure sensor, a liftable load corresponding to a position at the top end part of an arm is operated. CONSTITUTION:When a load is lifted by operating a boom-cylinder and an arm-cylinder, detected signals from a boom angle sensor 12 and an arm angle sensor 13 are momentarily inputted in a controller 15'. An arms position- operating means 25 in the controller 15' operates coordinate data at the top end part of an arm, and they are inputted in a moment-operating means 26. A detected signal from a cylinder pressure sensor 19 is inputted in the moment- operating means 26. By the moment-operating means 26, its detected value is compared with a value on a boom cylinder pressure table previously stored in a ROM 21, the pressure difference between them is operated, and moment about a pin at the base end part of a boom, which moment is caused by the force corresponding to this pressure difference, is operated and finally a lifted load is operated. In this way, the durability and maintainability of a safety device is improved.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hydraulic excavator that also serves as a crane and has a crane work slinging tool provided at the tip of a work attachment for construction machines, work vehicles and the like.

[0002]

2. Description of the Related Art FIG. 4 is a side view of a hydraulic excavator that also serves as a crane. In the figure, 1 is an upper swing body which is a vehicle body,
2 is a lower traveling body, 3 is a work attachment mounted on the front part of the upper swing body 1, 4 is a boom, 5 is an arm, 6
Is a bucket for excavation work, 7 is a bucket link, 8 is a crane work crane, 9 is a boom cylinder, 10 is an arm cylinder, 11 is a bucket cylinder, and 12 is a rotation angle of the boom 4 with respect to the vehicle body of the upper swing body 1. Boom angle sensor (constituting arm attitude detecting means) for detecting the position, 13 is an arm angle sensor (constituting arm attitude detecting means) for detecting the rotation angle of the arm 5 with respect to the boom 4, and 14 is a pin type provided on the sling gear 8. Reference numeral 15 is a load cell (constituting a load acting force detecting means), 15 is a controller mounted on the upper swing body 1, and 16 is a suspended load (the suspended load is W).

In a hydraulic excavator as shown in FIG. 4, a boom 4 and an arm 5 are sequentially connected to a front portion of an upper revolving structure 1 so as to be rotatable in the front-rear direction, and a fishing gear 8 is provided near the tip of the arm (5). And a boom angle sensor 12 and an arm angle sensor 13 which are arm posture detecting means.
And a pin-type load cell 14 which is a load acting force detecting means.
Based on the output signals from these detecting means, the controller 15 performs arithmetic processing to calculate the rated load moment by moment.

FIG. 5 shows the position of the tip of the arm (the sling 8
Is attached to the vicinity of the arm tip portion, and is therefore limited to the arm tip portion 17 for convenience of description). In the figure, 0 is the axis of the boom base end pin 18, which is the center of rotation of the boom 4, A is the axis of the boom tip pin (the boom tip pin is the same as the arm base pin), and B is the axis.
Is the axis of the arm tip portion 17, C is the axis of the boom center boss pin, D is the axis of the boom cylinder base end pin, and XX is the horizontal X axis with the center of rotation 0 as the origin. YY is the vertical Y-axis, L1 is the boom length between 0 and A, and L2 is the arm length between A and B. Therefore, when the hydraulic excavator is performing crane work, the boom angle sensor 1
When the arm angle sensor 13 detects the boom angle a, the arm angle sensor 13 detects the arm angle b, and inputs the output signal to the controller 15, the controller 15 causes the coordinate value (x, y) of the arm tip portion 17 to occasionally change. Calculation processing is being performed moment by moment.

[0005]

In the conventional hydraulic excavator that also serves as a crane, a pin type load cell having a strain gauge such as metal or semiconductor is used as the load acting force detecting means. The strain gauge is expensive to install, has a problem in durability, and is not perfect in terms of economy, maintenance, and safety. The present invention aims to solve the above problems.

[0006]

In the hydraulic excavator combined with the crane of the present invention, a cylinder pressure sensor is provided in the boom cylinder, and the boom cylinder pressure at the arm tip position at no load is plotted over the working range of the arm tip. The table is stored in the controller, and when a hanging load is applied to the arm tip, the signals from the boom angle sensor, arm angle sensor, and cylinder pressure sensor are input to the controller to correspond to the arm tip position. The hanging load is calculated. In that case, the lifting load is calculated by the differential pressure between the boom cylinder pressure when no load is applied and the boom cylinder pressure when the lifting load is applied. Further, when the hanging load corresponding to the arm tip position exceeds a predetermined value of the allowable load, an alarm is issued.

[0007]

Embodiments of the present invention will now be described in detail with reference to the drawings. FIG. 1 is a side view of essential parts showing a hydraulic excavator that also serves as a crane according to the present invention. In the figure, the same reference numerals are given to those using the same constituent elements as those in the prior art. 1
Reference numeral 9 is a cylinder pressure sensor provided for the bottom side oil chamber 20 of the boom cylinder 9 ', and dimension 1 is a line connecting the axis 0 of the boom base end pin 18 to the axis of the boom cylinder 9 (C and D). ), 15 'is a controller. It should be noted that the dimension 1 is a dimension that varies from moment to moment as the boom cylinder 9 ′ expands and contracts, but since it is 0D = constant and 0C = constant, it is calculated based on the boom angle a detected by the boom angle sensor 12. can do. Figure 2
FIG. 3 is a block diagram showing control of the hydraulic excavator that also serves as a crane of the present invention. In the figure, 21 is a controller 1
Reference numeral 5'is a memory, and 22 is an alarm generator such as a buzzer that emits an alarm sound and a lamp that lights up the operation panel. Figure 3
FIG. 8 is a diagram showing a boom cylinder pressure table (24) of arm front end positions when there is no load, plotted over the working range (23) of the arm front end portion 17. In the drawing, reference numerals a to s, s, s, s, s, and s are boom cylinder pressure values in the boom cylinder pressure table 24.

Next, the construction of the hydraulic excavator combined with the crane according to the present invention will be described with reference to FIGS. In the hydraulic excavator combined with the crane of the present invention, the cylinder pressure sensor 19 is provided in the bottom side oil chamber 20 of the boom cylinder 9 ′.
In addition, the boom cylinder pressure table (24) of the arm tip position at the time of no load plotted over the working range (23) of the arm tip section 17 is stored in the memory 21 of the controller 15 ′ in advance, and the load applied to the arm tip section 17 is suspended. When the force is applied, by inputting the signals from the boom angle sensor 12, the arm angle sensor 13, and the cylinder pressure sensor 19 to the controller 15 ′, the hanging load corresponding to the arm tip position is calculated. did. In that case, the lifting load is calculated by the differential pressure between the boom cylinder pressure when no load is applied and the boom cylinder pressure when the lifting load is applied. Further, when the hanging load corresponding to the arm tip position exceeds a predetermined value of the allowable load, the alarm generator 22 issues an alarm.

Next, the operation of the hydraulic excavator combined with the crane according to the present invention will be described. The boom cylinder pressure table (24) when there is no load on the arm tip portion 17 is stored in advance in the memory 21 of the controller 15 'equipped in the crane and hydraulic excavator of the present invention. When the hydraulic excavator that also serves as a crane performs crane work, the boom cylinder 9 ′ and the arm cylinder 10 are operated to lift the load 16 to be lifted. Signals from the boom angle sensor 12 and the arm angle sensor 13 are transmitted to the controller 1
By inputting to 5'instantaneously, the controller 1
At 5 ', the coordinate value (x, y) of the arm tip portion 17 is calculated (by the arm posture calculation means 25 in FIG. 2).
For example, the coordinate value (x1, y1) of the temporary point is calculated, and the signal is input to the moment calculating means 26. At the same time, the boom cylinder pressure signal (the cylinder pressure at this point is P) at the above point is input to the controller 15 ′. In the controller 15 ′, the memory 21
No load boom cylinder pressure (P) corresponding to the above coordinate values of the boom cylinder pressure table (24) stored in
Compared with the differential pressure ΔP (where ΔP = P−P)
0) is calculated. Then, the moment M about the boom base end pin 18 (rotation center 0) due to the differential pressure ΔP is calculated, and the hanging load W is calculated. The cylinder piston pressure receiving area on which the differential pressure ΔP acts is S, the distance from the center of rotation 0 to the boom cylinder axis (the line connecting C and D shown in FIG. 1) is 1, and the coordinate value of the arm tip 17 is shown. To (x1, y
1), the moment M and the hanging load W are calculated based on the following formula 1.

[0010]

[Equation 1]

As described above, the hanging load W and the coordinate values (x, y) are obtained, and the so-called rated load is calculated every moment.
When a state of exceeding% occurs, a signal is output from the moment calculation means 26 of the controller 15 ′ to the alarm generation command unit 27. The alarm generation command unit 27 makes a determination based on the signal, and outputs an alarm generation command signal to the alarm generator 27 (buzzer, lamp, etc.). The buzzer generates an alarm sound, or a lamp lights on an operation panel (not shown) or the like, so that the driver recognizes the alarm and performs a corresponding operation. When the allowable load limit is reached, a command signal from the moment calculation means 26 is sent via the boom rotation control calculation unit 28 and the arm rotation control calculation unit 29 to the boom cylinder hydraulic pressure control unit 30 and the arm cylinder hydraulic pressure control unit 31, respectively. Since it is output to, it is possible to stop lifting.

[0012]

In the conventional hydraulic excavator which also functions as a crane, a pin type load cell having a strain gauge such as a metal or a semiconductor is used as the load acting force detecting means. The strain gauge is expensive to install, has a problem in durability, and is not perfect in terms of economy, maintenance, and safety. However, in the crane combined hydraulic excavator of the present invention, the boom cylinder is provided with a cylinder pressure sensor, and the boom cylinder pressure table of the arm tip portion position at no load plotted over the working range of the arm tip portion is stored in the controller.
When a lifting load is applied to the arm tip, by inputting signals from the boom angle sensor, the arm angle sensor, and the cylinder pressure sensor to the controller, the lifting load corresponding to the arm tip position can be calculated. I chose In that case, the lifting load is calculated by the differential pressure between the boom cylinder pressure when no load is applied and the boom cylinder pressure when the lifting load is applied. Since the boom angle sensor is inexpensive and has sufficient durability, it is possible to improve economy, maintainability, and safety. Further, since the alarm is issued when the hanging load corresponding to the position of the arm tip exceeds the predetermined value of the allowable load, it is possible to ensure safety during crane work.

[Brief description of drawings]

FIG. 1 is a side view of essential parts showing a hydraulic excavator that also serves as a crane according to the present invention.

FIG. 2 is a block diagram showing control of the hydraulic excavator that also functions as a crane according to the present invention.

FIG. 3 is a boom cylinder pressure table at an arm tip position when there is no load.

FIG. 4 is a side view of a hydraulic excavator that also serves as a crane.

FIG. 5 is a side view of a main part for calculating an arm tip position.

[Explanation of symbols] 4 boom 5 arm 8 sling 9,3 'boom cylinder 10 arm cylinder 12 boom angle sensor 13 arm angle sensor 15, 15' controller 17 arm tip 18 boom base end pin 19 cylinder pressure sensor 21 memory 22 Alarm generator 24 Boom cylinder pressure table

Claims (3)

[Claims] 1. A boom and an arm are sequentially connected to a front part of a vehicle body so as to be rotatable in the front-rear direction, a sling is attached near the tip of the arm, and an arm posture detecting means and a load acting force detecting means are provided. It is a hydraulic excavator designed to perform crane work by installing a cylinder pressure sensor on the boom cylinder, and using the boom cylinder pressure table of the arm tip position at no load plotted over the working range of the arm tip as a controller. When the load is applied to the arm tip, the load corresponding to the arm tip position is input by inputting the signals from the boom angle sensor, the arm angle sensor, and the cylinder pressure sensor to the controller. A hydraulic excavator that doubles as a crane and is characterized by being operated. 2. The crane and hydraulic excavator according to claim 1, wherein the lifting load is calculated by the differential pressure between the boom cylinder pressure when there is no load and the boom cylinder pressure when there is a lifting load. A hydraulic excavator that also functions as a crane. 3. The crane and hydraulic excavator according to claim 1, wherein an alarm is issued when the hanging load corresponding to the arm tip position exceeds a predetermined value of the allowable load. Hydraulic excavator that doubles as a crane.