JPH0791841B2 - Hydraulic work machine speed controller - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an industrial vehicle having a lifting device such as a shovel loader, a dozer shovel, and a forklift truck, and particularly to a lifting device for lifting a load by hydraulic pressure, and a tilting device. It is suitable for use in an industrial vehicle having a tilt device.

(Prior Art) FIG. 5 shows an overall schematic view of a shovel loader which is an example of a field of use of the present invention. In the figure, the bucket c is loaded with earth and sand, the tilt cylinder d is actuated to incline the bucket c toward the vehicle body, and the lift cylinder b is actuated to lift the boom a upward. θ _B is the boom angle.

FIG. 3 shows an example of a hydraulic circuit of a conventional working machine. In the drawing, the pressure oil supplied from the hydraulic pump e drives the tilt cylinder d by the operation of the tilt control valve f, and drives the lift cylinder b by the operation of the lift control valve g when the tilt control valve f is in the neutral position (this). Is called the tilt priority circuit). g ₁ is the lift cylinder b raised position, g ₂ is the neutral position, g ₃ is the lowered position,
g ₄ indicates the floating position. h is bucket c (see FIG. 5)
It is a boom kickout electric detent that electrically actuates a boom kickout device (not shown) that automatically stops the load when it rises to an arbitrary set load height.

(Problems to be Solved by the Invention) When a vehicle having a tilt-priority working machine hydraulic circuit shown in FIG. 3 performs scooping work such as earth and sand, an operator operates the boom kickout device to operate the boom kickout device. Operates only the tilt control lever. A specific example of the relationship between the operation and the bucket load in this scooping operation is shown in FIG. 4 (a). In the figure, "lift" in the periods I and III means the lift of the lift arm a (see Fig. 5), and "tilt" in the periods II, IV and VI refers to the bucket c (see Fig. 5). It means tilting to the side, and “Dump” in the period of V means the opposite operation to “Tilt”. As you can see from the figure, "lift" and "tilt" so that the bucket load does not exceed the maximum hydraulic pressure.
The bucket is not fully filled during the scooping operation, and the bucket is returned in the dump direction so that the target object enters the bucket. During this dumping operation period V, the bucket vertical load F _v is reduced, and therefore the front tires of the vehicle (the fifth tire
There is a problem of inducing the slip of t) in the figure.

Further, FIG. 4 (c) is an explanatory diagram of the bucket blade locus in the case of the scooping operation described with reference to FIG. 4 (a). In the figure, the line indicated by W indicates the surface of the earth and sand to be scooped, the line indicated by A is the ideal blade edge locus of the bucket, and the line indicated by B is the scooping operation described in Fig. 4 (a). 3 is a bucket blade locus in the hydraulic circuit according to the related art described in FIG. 3). To carry out this scooping operation, the operator must lift the lift control lever (3rd
Alternately operating the n) in the figure and the tilt operating lever (m in FIG. 3), or holding the lift in a vehicle having a boom kickout device (not shown) which is a lift position holding device. As it is, only the tilt operation lever (m in FIG. 3) is operated to perform scooping. Of these two operating methods, the former operating method is a complicated repetition of a lift operation and a tilt operation, and the latter operating method is superior. However, in the latter operating method,
The holding position of the lift control valve g is the maximum lift position, and the lift speed when the tilt operation lever m is released (the period III in FIG. 4 (c)) is too large in the conventional hydraulic equipment for working machine, Since the operation speed of the bucket in the forward direction and in the upward direction cannot be controlled and soil and the like cannot be sufficiently scooped into the bucket, useless operation such as dump operation is required during the period V in FIG. 4 (c). There was a big problem that was. The fourth
FIG. 4B is a graph for explaining the working machine oil supply flow rate during the work shown in FIG. 4A.

(Means and Actions for Solving Problems) The present invention has been made in view of the above problems, and the lift operation lever and the tilt operation lever are electric levers that output a voltage corresponding to the lever displacement. , An arithmetic circuit for calculating the output signal value for the input from those electric levers, an output signal holding circuit for holding the output signal for a certain time, and a control valve for outputting to the lift control solenoid proportional valve and the tilt control solenoid proportional valve A controller is configured by the control circuit. The lift control solenoid proportional valve and the tilt control solenoid proportional valve respectively flow an oil amount proportional to the signal output from the controller to drive the lift cylinder and the tilt cylinder. Since the hydraulic working machine speed control device is configured in this manner, a boom kickout signal (a signal that automatically stops the load when the load height rises to a certain set load height) is issued by the lift operation lever. When the tilt operation lever is operated at some time, and then the tilt operation lever is returned to the neutral position, the lift output signal that is calculated according to the lift output signal calculation function that calculates the bucket rising speed according to the boom angle that is read in advance in the calculation circuit. Is output to the lift control valve for a certain period of time determined by the signal holding circuit to limit the bucket ascending speed and significantly improve the scooping performance.

Furthermore, the lift speed that depends on the boom angle is
By providing the lift speed adjustment switch, it is possible to freely adjust the lift speed within a certain range.

(Embodiment) An embodiment of the present invention will be described below with reference to the drawings.

In FIG. 1 (a), the lift operating lever 1 and the tilt operating lever 2 respectively have voltages X _L and X _T depending on the lever displacement.
An electric lever for outputting, the lever signal X _L and X _T
Also, the signal from the boom kickout switch 8 and the signal θ _B from the boom angle sensor 9 are taken into the input circuit 4 of the controller 3, the output signal value is calculated by the calculation circuit 5, and the output signal is calculated by the signal holding circuit 6. The control valve control circuit 7 outputs the lift output signal Y _L and the tilt output signal Y _T to the lift control solenoid proportional valve 11 and the tilt control solenoid proportional valve 12, respectively, while maintaining the values for a certain period of time. The lift control solenoid proportional valve 11 and the tilt control solenoid proportional valve 12 respectively supply an oil amount proportional to the signals Y _L and Y _T output from the controller 3 to the lift cylinder.
13 and the tilt cylinder 14 are driven to flow.

Next, as one specific example of the operation of the hydraulic working machine speed control device shown in FIG. 1 (a), which is an embodiment of the present invention, a working machine of a shovel loader will be described with reference to FIGS.
A description will be given with reference to FIGS. The external view of the shovel loader shown in FIG. 5 is the same in the embodiment of the present invention, and FIG. 5 is also referred to. And FIG. 2 (a)
And (b) correspond to FIGS. 4 (b) and (c) of the prior art, respectively, and the same reference numerals indicate the same,
C in FIG. 2 (b) is a specific example of the bucket blade locus to which the present invention is applied. Now bucket c on target W such as earth and sand
And the lift control lever 1 is moved to the boom kickout position (the raising position in FIG. 1 (a)), and the bucket c
When the bucket c is pushed by the tire driving force of the vehicle while advancing the blade edge of the object W toward the object W, and the horizontal resistance (F _{H in} FIG. 4 (a)) increases and pushing becomes impossible, the tilt operation lever 2 is operated. Then, the object W is scooped into the bucket c. When the operator determines that the amount of scooping is insufficient by operating the tilt operation lever 2 at this time, the tilt operation lever 2 is returned to the neutral position. Here, the lift speed is calculated in the calculation circuit 5 by the boom angle signal detected by the boom angle sensor 9, and the lift control solenoid proportional valve
Since the lift output signal Y _L to 11 is controlled, the boom a rises at a speed suitable for scooping. When the bucket blade edge penetrates the object due to the rise of the boom a, the tilt is further repeated. The relationship between the lever operation and the working machine oil supply flow rate in this series of scooping work is shown in Fig. 2 (a).
As described above, the oil supply flow rate to the lift cylinder 13 during the scooping is reduced as compared with the prior art FIG. 4 (b). By automatically controlling the lift speed during the scooping work in this way, the scooping work can be easily performed by operating only the tilt operation lever 2, and the lift speed corresponding to the tilt speed can be obtained. The direction of penetration of the object W toward the object with high scooping efficiency becomes a bucket blade locus as shown by C in FIG. 2 (b), which is extremely close to the ideal locus A, so that the work efficiency is remarkable. Improve,
The operation of rolling the object W into the bucket c by the dumping operation as shown by V in FIG. Note that the lift speed increases at the maximum speed as before when the boom angle exceeds the angle at the time of scooping or when the set time set in the signal holding circuit 6 elapses after ending the tilt operation, so the lift speed after scooping The boom rise time is the same as before.

Further, FIG. 1 (c) is an example of calculation of the lift output signal Y _L (proportional to the lift speed) after the tilt operation is released during the boom kickout operation, and the lift output signal Y _L is obtained from the boom angle θ _B. It is output to the lift control solenoid proportional valve 11. In the figure, the shaded area shows the range in which the lift output signal (Y _L ) can be adjusted by operating the lift speed adjustment switch 21 in FIG. 1 (a).

FIG. 1 (b) is a flow chart of the calculation in the controller 3, and since the contents have been described in detail above, the description thereof will be omitted.

(Effects of the Invention) Since the present invention is configured as described above in detail, the complicated operation of alternately operating the lift operation lever and the tilt operation lever is not necessary, and the operation of only the tilt operation lever can be performed for the scooping operation. This is easy and the bucket blade locus is very close to the ideal locus, so unnecessary work such as dumping with the tilt control lever is not required and work efficiency is greatly improved. Further, as described above, since the dumping operation is unnecessary, the vertical load on the bucket is not reduced and the slip of the front tires is not induced, which is a great effect.

[Brief description of drawings]

FIG. 1 (a) schematically shows a hydraulic working machine speed control device according to an embodiment of the present invention, FIG. 1 (b) is a flowchart of calculation in a controller, and FIG. 1 (c) is a boom angle. 2A is a graph of a specific example showing the working machine oil supply flow rate, FIG. 2B is an explanatory view showing a bucket blade locus, and FIG. 3 is a conventional graph. Hydraulic circuit diagram, Fig. 4 (a), (b),
(C) shows the operation method, the working machine oil supply flow rate, and the bucket blade locus of the conventional scooping work, and FIG. 5 is an external view of the shovel loader. 1 …… Lift control lever, 2 …… Tilt control lever, 3 ……
Controller, 9 …… Boom angle sensor, 11 …… Lift control solenoid proportional valve, 12 …… Tilt control solenoid proportional valve, 13 …… Lift cylinder, 14 …… Tilt cylinder, 2
1 …… Lift speed adjustment switch.

Claims (1)

[Claims] 1. A hydraulic system for a working machine, which raises and tilts a bucket by hydraulic pressure, comprises an electric lift operating lever and a tilt operating lever which output an electric signal corresponding to a lever displacement; A controller that calculates the bucket rising speed during boom kickout operation based on the boom angle and outputs an electric signal; a lift control solenoid proportional valve and a tilt control solenoid that flow an oil amount corresponding to the electric signal to the lift cylinder and tilt cylinder A hydraulic working machine speed control device comprising a proportional valve.