JPH036286B2 - - 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.

[Conventional technology]

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 of 7 to 9 are constant, the angular velocities of boom 2, arm 3, and bucket 4 are determined by the boom angle (the angle of boom 2 with respect to main body 1), the arm angle (the angle of arm 3 with respect to boom 2), and the bucket angle ( It changes depending on the angle of the bucket 4 with respect to the arm 3). 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 can be seen from this graph, when the arm angle θ is the minimum and maximum, that is, when the hydraulic cylinder 8 is at the most contracted and most extended, the angular velocity of the arm 3 is large, so at the stroke end of the hydraulic cylinders 7 to 9, the operation If the operator does not operate the hydraulic cylinders 7 to 9 to reduce the speed to zero, the pistons of the hydraulic cylinders 7 to 9 will impact impactively at the end of the stroke. For this reason, conventionally, a cushion valve is provided inside the hydraulic cylinders 7 to 9, and a cushion valve is provided inside the hydraulic cylinders 7 to 9.
When the piston reaches the stroke end, the pressure oil supplied to the hydraulic cylinders 7 to 9 is cut off, but in this case, the structure of the hydraulic cylinders 7 to 9 becomes complicated.

The present invention has been made to solve the above-mentioned problems, and an object of the present invention is to provide a method for controlling the speed of a front member of a hydraulic excavator that can prevent a collision at the stroke end of a hydraulic cylinder.

[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 in which a hydraulic cylinder that drives the front member is supplied with pressure oil at a flow rate corresponding to an output signal of an operating lever. The angle is detected, a conversion signal is obtained by converting the angle signal with a function that becomes zero when the angle signal of the front member is maximum and minimum, and the conversion signal is multiplied by the output signal of the control lever to generate a control signal. is determined, and the flow rate of the pressure oil flowing into the hydraulic cylinder is controlled using 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.

[Embodiment] 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 converts the output signal 8, that is, the arm angle signal Θ, with a function that becomes zero when the arm angle signal Θ is maximum and minimum, and 22 is the output signal of the function generator 21, that is, the conversion signal Q, and the output of the operating lever 19. 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 is set so that the conversion signal Q becomes zero when the arm angle signal Θ is maximum or minimum, the hydraulic cylinder 8 Since the speed of the hydraulic cylinder 8 becomes zero, a collision at the stroke end of the hydraulic cylinder 8 can be prevented.

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. Therefore, 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,
If shock prevention control at the cylinder stroke end is not required, the discharge controller of the variable discharge pump may be controlled by a signal from the operating lever without using the function generator. In addition, in the area where the arm angle signal Θ is near the maximum and minimum,
When the arm angle signal Θ is maximum and minimum, the conversion signal Q
Convert the arm angle signal Θ with a function such that θ becomes zero, and in other regions, convert the arm angle signal Θ with an inverse function of the function representing the relationship between the arm angle θ and the arm angular velocity shown in Figure 2. For example, when the output signal of the operating lever 19 is constant in a region other than the region where the arm angle signal Θ is around the maximum and minimum,
The angular velocity of arm 3 is constant regardless of the arm angle.

〔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,
Since the angular velocity of the front member is zero when the angle of the front member is at its maximum or minimum, it is possible to prevent a collision at the stroke end of the hydraulic cylinder. 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. 1...Body, 2...Boom, 3...Arm, 4
...Bucket, 7-9...Hydraulic cylinder, 10...
...Variable discharge amount pump, 17...Discharge amount 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 signal is obtained by converting the angle signal with a function that becomes zero when the angle signal of the front member is maximum and minimum, and the control signal is obtained by multiplying the conversion signal by the output signal of the control lever. A method for controlling the speed of a front member of a hydraulic excavator, characterized in that the flow rate of pressure oil flowing into the hydraulic cylinder is controlled by a control signal. 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.