JPH0791840B2 - 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 lift arm a upward.

FIG. 3 shows an example of a hydraulic circuit of a conventional working machine. In the figure, 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. g ₁ is a lift position of the lift cylinder b, g ₂ is a neutral position, g ₃ is a lower position, and g ₄ is a floating position. h is a boom kickout electric detent that electrically operates a boom kickout device (not shown) that automatically stops the load when the bucket c (see FIG. 5) rises to a certain set load height. Is.

(Problems to be Solved by the Invention) FIG. 4 is a specific example of the relationship between the operation and the bucket load when the vehicle having the hydraulic circuit of the related art shown in FIG. 3 performs a scooping operation such as earth and sand. It shows in (a). In the figure I
“Lift” during periods III and III means the lifting of the lift arm a (see FIG. 5), and “tilt” during periods II, IV and VI.
Indicates that the bucket c (see FIG. 5) is tilted toward the vehicle body, and “Dump” in the period of V means the opposite operation to “Tilt”. As can be seen from the figure, the bucket is loaded by repeating "lift" and "tilt" so that the bucket load does not exceed the maximum oil pressure. Is operated so that the target object enters the bucket.
During this dumping operation period V, the bucket vertical load F _V decreases, which causes a problem of inducing slip of the front tires of the vehicle (t in FIG. 5).

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 is the upper surface of the earth and sand to be scooped, the line indicated by A is the ideal blade edge trajectory of the bucket, and the line indicated by B is the scooping operation described in Fig. 4 (a). Fig. 3 is a bucket blade locus in a hydraulic circuit according to the related art). To carry out this scooping operation, the operator alternately operates the lift operation lever (n in FIG. 3) and the tilt operation lever (m in FIG. 3) or uses the boom kick which is a lift position holding device. In a vehicle having an out device (not shown), only the tilt operation lever (m in FIG. 3) is operated to perform scooping while holding the lift. Of these two operating methods, the former operating method is a complicated repetition of lift operation and tilt operation, and the latter operating method is easier.
However, in the latter operating method, the holding position of the lift control valve g is the maximum lift position, and when the tilt operating lever m is released in the conventional hydraulic equipment for working machine (III in FIG. 4 (c)). Period), the operating speed of the bucket in the forward direction and in the upward direction cannot be controlled because the lift speed is too high, and it is not possible to fully scoop the soil into the bucket. Therefore, the period V in FIG. 4 (c) There was a big problem that a wasteful operation such as a dump operation in was necessary. 4 (b) is a graph for explaining the working machine oil supply oil amount in FIG. 4 (a).

(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. . A controller including an arithmetic circuit that calculates an output signal value with respect to the input from the electric lever, an output signal holding circuit that holds the output signal for a certain time, and a control valve control circuit that outputs the lift control electromagnetic proportional valve. Make up. The lift control solenoid proportional valve and the tilt control solenoid proportional valve respectively drive an oil amount proportional to a signal output from the controller to drive the lift cylinder and the tilt cylinder. Since the hydraulic work machine speed control device is configured in this way, when the tilt operation lever is operated to the tilt position while the boom operation signal is being output by the lift operation lever, the output time of the tilt operation lever output signal is The lift output signal determined from the output signal arithmetic function previously read in the arithmetic circuit is calculated from the change in the bucket angle, and when the operation of the tilt operation lever is interrupted, the lift control solenoid proportional valve determines it by the output signal holding circuit. By outputting the lift output signal for a certain period of time, the lift speed during the scooping work is controlled, and the scooping workability is greatly improved.

(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 are respectively the voltage X _L and
It is an electric lever that outputs X _T , and this lever signal X _L
The signal theta _B from the signal and the bucket angle sensor 9 from X _T and the boom kick-out switch 8 incorporation into the input circuit 4 of the controller 3 calculates an output signal value calculation circuit 5, the in the signal holding circuit 6 Te at Hold the output signal value for a certain period of time and output the lift output signal from the control valve control circuit 7.
Y _L and tilt output signal Y _T are output to lift control solenoid proportional valve 11 and tilt control solenoid proportional valve 12, respectively. The lift control solenoid proportional valve 11 and the tilt control solenoid proportional valve 12 are designed to flow oil amounts proportional to the signals Y _L and Y _T output from the controller 3 to the lift cylinder 13 and the tilt cylinder 14, respectively, to drive them. There is.

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. Since the external view of the shovel loader shown in FIG. 5 is the same in the embodiment of the present invention, reference is also made to FIG. 5 and the reference numerals in this drawing. 2 (a) and 2 (b) respectively show the fourth example of the prior art.
It corresponds to FIGS. (B) and (c), the same reference numerals indicate the same things, and C in FIG. 2 (b) is a specific example of the bucket blade locus to which the present invention is applied. Now, the bucket c is penetrated into the object w such as earth and sand, and the lift operation lever 1 is operated to the boom kickout position (the raising position in FIG. 1A) to advance the blade edge of the bucket c with respect to the object w. While pushing the bucket c with the tire driving force of the vehicle, when the horizontal resistance (F _{H in} FIG. 4 (a)) increases and pushing becomes impossible, the tilt operation lever 2 is operated to move the object w into the bucket c. Scoop 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. Object w here
Type, road condition and inclination, engine throttle opening,
The lift output signal Y _L calculated by a function pre-read in the calculation circuit 5 by the operation time ΔT of the tilt operation lever 2 and the tilt change amount Δθ _B of the bucket c determined by the skill level of the operator and the work cycle time. Is output to the lift control solenoid proportional valve 11, and the lift arm a
Rises. The relationship between the lever operation and the work machine oil flow rate in this series of scooping work is as shown in FIG. 2 (a), and the amount of oil in the lift cylinder 13 during scooping is that of the prior art shown in FIG. 4 (b). ), The lift speed can be controlled to a speed commensurate with the tilt speed. In this way, by automatically controlling the lift speed during scooping work,
Since only the tilt operation lever 2 can be operated, the scooping work can be done easily, and the lift speed corresponding to the tilt speed can be obtained, so that the direction of penetration of the bucket c into the object w is higher toward the scooping efficiency. C in FIG. 2 (b)
The bucket blade locus as shown in Fig. 2 is very close to the ideal locus A, so the work efficiency is improved and
The operation of rolling the object w into the bucket c by the dumping operation as shown by V in FIG. 4 (c), which is a conventional technique, is also unnecessary.

Note that FIG. 1 (c) is an example of calculation of the lift speed after the tilt operation is released during the boom kickout operation. The lift output signal Y _L is obtained from the average tilt angular velocity θ _B during the tilt operation, and the lift control electromagnetic proportional It is output to the valve 11.

Further, the holding time of the lift output signal in the signal holding circuit 6 is set to be longer than the operation release time of the tilt operation lever in normal work.

Further, FIG. 1 (b) shows a flowchart of calculation in the calculation circuit 5.

(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 unnecessary, and the operation of only the tilt operation lever can be performed for the scooping work. It can be done easily, and since the bucket blade locus becomes extremely close to the ideal locus, useless operations such as dumping with the tilt operation lever are not required, and work efficiency is greatly improved. Further, since the dumping operation is not necessary, 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) is a circuit diagram schematically showing a hydraulic working machine speed control device according to an embodiment of the present invention, and FIG. 1 (b) is a flow chart of controller output signal calculation, and FIG. 1 (c). ) Is a specific example of lift output signal calculation, FIG. 2 (a)
Is a graph of one specific example showing the amount of working machine oil supply, FIG. 2 (b) is an explanatory view showing the bucket blade locus, FIG. 3 is a hydraulic circuit diagram of a conventional one, and FIGS. 4 (a) and 4 (b). , (C) are operation methods in conventional scooping work, working machine oil supply oil amount, bucket blade locus, and FIG. 5 is an external view of a shovel loader. 1 …… Lift control lever, 2 …… Tilt control lever, 3 ……
Controller, 11 …… Lift control solenoid proportional valve, 12
...... Tilt control solenoid proportional valve, 13 …… Lift cylinder, 14 …… Tilt cylinder.

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 outputs the electric signal by calculating the bucket rising speed during the boom kickout operation based on the bucket tilting speed during the bucket tilting operation; and a lift control electromagnetic that causes an oil amount corresponding to the electric signal to flow to the lift cylinder and the tilt cylinder. A hydraulic working machine speed control device comprising: a proportional valve and a tilt control solenoid proportional valve;