JPS6252096B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a method for controlling the speed of front members such as a boom, an arm, and a bucket of a hydraulic excavator.

[Prior Art] FIG. 1 is a diagram showing a backhoe hydraulic excavator. In the figure, 1 is a main body equipped with a prime mover, hydraulic pump, valves, driver's seat, etc., 2 is a boom pivoted to the main body 1, 3 is an arm pivoted to the boom 2, and 4 is pivoted to the arm 3. Baketto, 5,6
is a link, 7 is a hydraulic cylinder that rotates the boom 2, 8 is a hydraulic cylinder that rotates the arm 3, and 9 is a hydraulic cylinder that rotates the bucket 4.

[Problem that the invention seeks to solve]

In this hydraulic excavator, the hydraulic cylinder 7
9 rotates the front members, that is, the boom 2, arm 3, and bucket 4. Since the boom 2, arm 3, bucket 4, and hydraulic cylinders 7 to 9 form a link mechanism, the hydraulic cylinder Even if the speeds 7 to 9 are constant, the boom angle (the angle of boom 2 with respect to main body 1), arm angle (the angle of arm 3 with respect to boom 2), bucket angle (the angle of bucket 4 with respect to arm 3)
Accordingly, the angular velocity of the boom 2, arm 3, and bucket 4 changes. For example, even if the speed of the hydraulic cylinder 8 is the same, the angular velocity of the arm 3 is different when the arm 3 is at the position shown by the solid line and when the arm 3 is at the position shown by the two-dot chain line. FIG. 2 is a graph showing the relationship between the arm angle θ and the angular velocity of the arm 3 when the velocity of the hydraulic cylinder 8 is constant. As you can see from this graph, arm angle θ
The angular velocity of the arm 3 is large when is at its minimum or maximum, that is, when the hydraulic cylinder 8 is at its most contracted or most extended position. In this way, even if the operator controls the flow rate of pressure oil flowing to the hydraulic cylinders 7 to 9, that is, the speed of the hydraulic cylinders 7 to 9, to a constant value, the boom 2, arm 3. Since the angular velocity of the bucket belt 4 changes, the speed of the tip of the bucket belt 4 changes significantly depending on the attitude of the front part, resulting in poor operability.

This invention was made to solve the above-mentioned problems, and is a front member speed control method in which the angular velocity of the front member is constant regardless of the angle of the front member when the output signal of the operating lever is constant. The purpose is to provide

[Means for solving problems]

In order to achieve this object, the present invention provides a method for controlling the speed of a front member of a hydraulic excavator that supplies pressure oil at a flow rate according to an output signal of an operating lever to a hydraulic cylinder that drives the front member. The angle of the front member is an inverse function of a function representing the relationship between the angle of the front member and the angular velocity when the angle is detected and the flow rate of pressure oil flowing to the hydraulic cylinder is controlled by a constant output signal of the operating lever. A conversion signal is obtained by converting the signal, the conversion signal is multiplied by the output signal of the operating lever to obtain a control signal, and the flow rate of the pressure oil flowing into the hydraulic cylinder is controlled by the control signal.

[Effect]

In this method of controlling the speed of the front member of a hydraulic excavator, the flow rate of pressure oil flowing into the hydraulic cylinder is controlled by the control signal, so the speed of the hydraulic cylinder is a value corresponding to the product of the conversion signal and the output signal of the operating lever. becomes.

〔Example〕

FIG. 3 is a diagram showing an apparatus for carrying out the method for controlling the speed of a front member of a hydraulic excavator according to the present invention. In the figure, 10 is a hydraulic cylinder 8
11 is a charge pump, 12 is a relief valve connected to the charge pump 11, 13 and 14 are check valves, 15 is a flushing valve, 16 is a relief valve, 17 is a pump 1
0 is a discharge amount controller, 18 is an arm angle detector, 19 is an operating lever for the arm 3, and 20 is a control device.

FIG. 4 is a diagram showing details of the control device 20 shown in FIG. 3. In the figure, 21 is the angle detector 1
a function generator 22 for converting the output signal of 8, that is, the arm angle signal Θ, by an inverse function of the function representing the relationship between the arm angle θ and the arm angular velocity shown in FIG.
is the output signal of the function generator 21, that is, the conversion signal Q
The discharge amount controller 17 is controlled by the output signal of the multiplier 22, that is, the control signal.

That is, in the front member speed control method according to the present invention, a control signal is obtained by multiplying the conversion signal Q corresponding to the arm angle signal Θ by the output signal of the operating lever 19, and this control signal is used to control the discharge amount controller 17. By controlling the pump 10
The angular velocity of the arm 3 is controlled by setting the discharge amount of the hydraulic oil to a value corresponding to the control signal and setting the flow rate of the pressure oil flowing into the hydraulic cylinder 8 to a value corresponding to the control signal. Since the function of the function generator 21 is the inverse of the function representing the relationship between the arm angle θ and the arm angular velocity shown in FIG. 2, when the output signal of the operating lever 19 is constant, regardless of the arm angle. Since the angular velocity of the arm 3 is constant, it is possible to prevent the speed of the tip of the bucket bag 4 from changing significantly depending on the attitude of the front part.

In the above-mentioned embodiment, the method for controlling the speed of the arm has been described, but the same applies to other front members, such as the boom and the bucket. Further, in the above embodiment, a backhoe hydraulic shovel has been described, but the same applies to a loading hydraulic shovel. Further, in the above embodiment, the arm angle was directly detected by the arm angle detector 18, but the boom angle, arm angle, and bucket angle can be indirectly detected by detecting the extension amount of the hydraulic cylinders 7 to 9. It's okay. Furthermore, the arithmetic unit may be constructed of an analog circuit or a digital circuit such as a microcomputer. Furthermore, in the above embodiment, the discharge controller 17 of the variable discharge pump 10 is controlled by the control signal to control the flow rate of the pressure oil flowing into the hydraulic cylinder 8, but the control signal is not used to control the directional control valve. , the flow rate of pressure oil flowing into the hydraulic cylinders 7 to 9 may be controlled. However, when controlling the directional control valve, the hydraulic cylinder 7
~9. Since the flow rate flowing into the tank is controlled by a throttle, if the load pressure changes, the flow rate of the pressure oil flowing into the hydraulic cylinders 7 to 9 will change, so it is recommended to control the discharge rate controller of the variable discharge rate pump. desirable. In addition, two function generators are installed, and the angle signals of the front member are converted by different function generators during excavation and return, so that the speed of the front member during return is greater than the speed of the front member during excavation. This can also improve work efficiency. moreover,
When constant speed control of each front member is not required, such as during soil dumping with a bucket, use the control lever signal to control the discharge controller of the variable discharge pump, without using a function generator. It's okay. In addition, in the area where the arm angle signal Θ is near the maximum and minimum, the arm angle signal Θ is converted with a function such that the conversion signal Q is zero when the arm angle signal Θ is maximum and minimum, and in other areas, If the arm angle signal Θ is converted by an inverse function of the function representing the relationship between the arm angle θ and the arm angular velocity shown in FIG. 2, a collision at the stroke end of the hydraulic cylinder can be prevented.

〔Effect of the invention〕

As explained above, in the speed control method of the front member of a hydraulic excavator according to the present invention,
When the output signal of the operating lever is constant, the angular velocity of the front member is constant regardless of the angle of the front member, resulting in good operability. As described above, the effects of this invention are remarkable.

[Brief explanation of the drawing]

Fig. 1 is a diagram showing a backhoe hydraulic excavator, Fig. 2 is a graph showing the relationship between the arm angle and arm angular velocity when the speed of the hydraulic cylinder is constant, and Fig. 3 is a graph showing the relationship between the arm angle and arm angular velocity when the speed of the hydraulic cylinder is constant.
The figure shows a device for carrying out the method for controlling the speed of a front member of a hydraulic excavator according to the present invention;
FIG. 4 is a diagram showing details of the control device shown in FIG. 3. DESCRIPTION OF SYMBOLS 1...Main body, 2...Boom, 3...Arm, 4...Bucket, 7-9...Hydraulic cylinder, 10...Variable discharge rate pump, 17...Discharge rate controller, 18...Arm angle detector, 19...Operation lever, 20... Control device, 21...function generator, 22...multiplier.

Claims (1)

[Scope of Claims] 1. A method for controlling the speed of a front member of a hydraulic excavator that supplies pressure oil at a flow rate according to an output signal of an operating lever to a hydraulic cylinder that drives the front member, the method comprising: detecting the angle of the front member; A conversion in which the angle signal of the front member is converted by an inverse function of a function representing the relationship between the angle and angular velocity of the front member when the flow rate of pressure oil flowing into the hydraulic cylinder is controlled by a constant output signal of the operating lever. A front side of a hydraulic excavator, characterized in that a signal is obtained, a control signal is obtained by multiplying the conversion signal and an output signal of the operating lever, and the flow rate of pressure oil flowing into the hydraulic cylinder is controlled by the control signal. How to control the speed of a member. 2. A front member of a hydraulic excavator according to claim 1, wherein the flow rate of pressure oil flowing into the hydraulic cylinder is controlled by controlling a discharge controller of a variable discharge pump with the control signal. speed control method.