JPS5980505A - Hydraulic cylinder driving device - Google Patents

Abstract

PURPOSE:To control the dropping and rising speed of a piston of a hydraulic cylinder continuously from high speed to slow speed by applying an electric pulse signal to a solenoid switching valve to control the operation. CONSTITUTION:A solenoid switching valve 9 includes the first solenoid 10 for controlling the oil pressure 4 of a hydraulic cylinder in such a manner as to lower a piston rod and the second solenoid 20 for controlling the oil pressure of the hydraulic cylinder in a manner to raise the piston rod, wherein an electric pulse signal 23 is output from a pulse cycle setting circuit 21 and a pulse width setting circuit 22. Transistors 25, 26 are applied by a change-over switch 24 to selectively apply an electric current to solenoids 19, 20, so that the speed of a piston of a hydraulic cylinder 4 is controlled by changing the duty ratio of the electric pulse signal 23.

Description

[Detailed description of the invention] The present invention relates to a drive device for a hydraulic cylinder.

Hydraulic cylinders are widely used as is well known, but for example, the work vehicle used for the road cutting method, which is one of the asphalt road repair methods, that is, the road cutter, has a tool that cuts the road surface, that is, a bit. It is attached to the outer periphery of a rotating body, that is, a rotor, and the rotating bit is driven into the road surface by a hydraulic cylinder to cut the road surface. The descending or ascending speed of the piston of the hydraulic cylinder is related to the hardness of the asphalt road surface, the accuracy of setting the cutting depth, the driving force of the rotor, etc. In other words, if the piston of the hydraulic cylinder is lowered at a sieve speed when the road surface is hard, a tremendous force acts on the bit, which may exceed the rotational drive torque of the rotor and cause the rotor to stop. Moreover, the level of the bit, that is, the cutting depth, becomes too shallow or too deep, making it difficult to set it accurately. The conventional hydraulic seven-cylinder drive system has a drawback in that it is not possible to continuously and accurately adjust the lowering and raising speeds of the piston of the hydraulic cylinder from high speed to very low speed.

The purpose of the present invention is to eliminate the above-mentioned drawbacks of conventional devices,
To provide a hydraulic cylinder drive device capable of continuously and accurately controlling the lowering and raising speeds of a piston of a hydraulic cylinder from high speed to very low speed.

Prior to describing a preferred embodiment of the present invention, an example of a conventional hydraulic cylinder drive device will be described with reference to FIG. 1 for a better understanding of the present invention.

The cutter 1 includes a rotor 2 that is rotated by a drive device (not shown), and a bit 6 that is attached to the outside of the rotor 2. The rotor 2 is connected to a piston rod 5 of a hydraulic cylinder 4, and is raised or lowered as the piston rod 5 moves upward or downward. The hydraulic cylinder 4 has a first hydraulic chamber 6 for lowering the piston rod 5 and a second hydraulic chamber 7 for raising the piston rod 5. Solenoid switching valve 9
to the oil sump 10 via the solenoid switching valve? further from 70 to the oil tank 1 via the divider 11 and the pump 12.
6. The second hydraulic chamber 7 also includes a pilot check valve 14, a 20th flow adjustment valve 15, a counterbalance valve 16, and an electromagnetic switching valve 9f! to oil sump 10 via c,
Alternatively, from the electromagnetic switching valve 9, a flow divider 11,
It also communicates with an oil tank 16 via a pump 12.

17 and 18 are relief valves.

The electromagnetic switching valve 9 is a known switching valve, and includes a first solenoid 19 and a second solenoid 20. When the first solenoid 19 is energized, the first hydraulic chamber 6 is depressurized. The second hydraulic chamber 7 is connected to a pump 12 so as to be pressurized. Further, when the second solenoid 20 is energized instead of the first solenoid 19, the first hydraulic chamber 6 is communicated with the pump 12 so as to be pressurized, while the second hydraulic chamber '7 is Oil sump 1 to be depressurized
Connected to 0. Raising or lowering the hydraulic cylinder
This is done by selectively energizing the first and second solenoids; during the upward movement, the first solenoid 19 is continuously energized, and during the downward movement, the second solenoid 20 is continuously energized. W, the rising speed is controlled by adjusting the opening degree of the second flow rate regulating valve 15, and the descending speed is controlled by adjusting the opening degree of the first flow rate regulating valve 8.

In this way, in the conventional device, the speed of the upward movement and downward movement of the piston rod 5 of the hydraulic cylinder 4 is adjusted by adjusting the opening number of the second flow rate control valve 15 and the first flow rate control valve 8, respectively. Since it was controlled, there were disadvantages in that the number of parts in the hydraulic circuit was large and the cost was high, and there was also a large pressure loss in the hydraulic circuit, and the piston speed was difficult to adjust.

The present invention is to eliminate the above-mentioned drawbacks in the conventional mL device.

According to the present invention, in order to achieve the above object, there is provided an electromagnetic switching valve for controlling the oil pressure of a hydraulic cylinder in which a controlled object is connected to a piston rod, and an electrical pulse No. 1 mark on the electromagnetic switching valve. and a control circuit for controlling the operation of the valve, and the electromagnetic switching valve m1 has a first control circuit that controls the hydraulic pressure of the hydraulic cylinder in the direction of lowering the piston rod when the electromagnetic switching valve m1 is moved. a solenoid and a second solenoid that, when actuated, controls hydraulic pressure in the direction of raising the piston rod; A hydraulic seven cylinder drive device is provided which selectively applies pressure and changes the impact coefficient of the pulse signal to vary the rising or falling speed of the MIJ piston rod.

That is, the oil pressure/cylinder wAf as shown in FIG.
In the hydraulic circuit associated with the MJ, the piston rod of the hydraulic cylinder continuously rises and falls, but in the device according to the present invention, the piston rod of the hydraulic cylinder rises and falls intermittently.

For example, in a work vehicle such as a road cutter, even if the piston rod of the hydraulic cylinder falls intermittently, the piston rod will fall due to the electric pulse number 11 issued by - If the precision is 1, the rotor will rotate. Hydraulic circuit becomes positive due to inertia etc.
7. Cutting is possible without leafing, and therefore the hydraulic cylinder drive device according to the present invention works effectively.

The details of the structure, operation and effect of the present invention will be made clear by the detailed description of the preferred embodiment Ia of the present invention, which will be explained below with reference to the drawings.

FIG. 2 is a block diagram of a preferred embodiment of the hydraulic cylinder drive device according to the present invention, and FIG. 5 is a block diagram of the electromagnetic switching valve 9 of FIG.
FIG. 2 is an electrical circuit diagram for energizing the first and second solenoids 19 and 20 of the present invention.

In the embodiment of the present invention shown in FIG. 2, the first flow control valve 8, the second flow control valve 15,
The counterbalance valve 16 is omitted. In this embodiment, the rising and falling speed of the piston rod 5 of the hydraulic cylinder 4 is not controlled by these flow control valves, but by an electromagnetic pulse signal output from an electric circuit as shown in FIG. Switching valve? This is because the control is performed by selectively energizing the first and second solenoids 19 and 20.

In FIG. 6, 21 is a pulse period setting circuit which is known per se, and 22 is a pulse width setting circuit which is also known per se. As shown in FIG. A pulse signal 26 is output, which is selectively applied by the changeover switch 24 to the switching transistor 25 for energizing the first solenoid 1 and 9 or the transistor 26 for energizing the second solenoid 20, respectively. It is designed to turn on. The true period of the pulse period T is adjusted by a changeover switch 27, and the pulse width t is adjusted by a variable resistor 28. In actual control, in order to raise or lower the piston of the hydraulic cylinder 4, the first solenoid 19 or the second solenoid 20 is selected and energized by the changeover switch 24 as described above, and the speed is set as follows. The control is performed by changing the impulse coefficient of the electrical pulse signal 26, for example, the electrical pulse signal 2
Control may be performed by changing the period T=1 while keeping the pulse width t6 constant.

According to the experiment according to this example, the following experimental results were obtained.

Hydraulic circuit conditions (li) The total amount of oil flowing out from point A in Figure 2 was adjusted to 8 liters/min.

(2) The pulse width t of the electrical pulse signal is 25Tr.
It was set to LSeC.

(3) The cylinder 4 used had a bore diameter of 80 mm and a piston rod diameter of 50 mm. Experimental results When the hydraulic cylinder 4 was driven under the above conditions, switch 2
When 4 selected the first solenoid 19, the piston rose 51111.9 m and the second solenoid 20
When I selected , it fell for 1.6 seconds. At this time, the pulse period T is changed in the range of 2 see to Q, 3 SeC. LAeC~6.6WIW
Increase in LAeC or 0.8”/sec ~5.
It descended at 3”/see.

According to the present invention, with the above structure, there is little pressure loss in the hydraulic circuit, fewer hydraulic parts are required, and the electric circuit is simple, so the cost is low, and the speed of the cylinder can be easily adjusted down to very small speeds. etc., it has significantly superior effects compared to conventional devices.

Furthermore, when the present invention is applied to a kerosene cutter, no unreasonable force is applied to the rotor, the rotor can be lowered at a speed appropriate to the hardness of the road surface, and the depth of cut can be easily set. , and other excellent effects.

[Brief explanation of drawings]

Fig. 1 is a block diagram showing the hydraulic system of a conventional hydraulic cylinder drive system, Fig. 2 is a block diagram showing the hydraulic system of a hydraulic cylinder drive device according to an example of the present invention, and Fig. 6 is a block diagram showing the hydraulic system of a conventional hydraulic cylinder drive device. FIG. 2 is an electric circuit diagram for energizing the solenoid of the electromagnetic switching valve in the embodiment 1+lJ shown in FIG. 2, and FIG. 4 is a waveform diagram of the electrical pulse signal generated in FIG. 6. Explanation of symbols 4 ... Hydraulic cylinder, 5... Piston rod, ?-
...Solenoid switching valve, 19...First solenoid, 20...
-Second solenoid, 26... electrical pulse signal. Agent Patent Attorney Isao Fujimoto-+20 et al+3■ Spear 41 points

Claims (1)

[Claims] Equipped with an electromagnetic switching valve for controlling the oil pressure of a hydraulic cylinder having a controlled object connected to a piston, and a control circuit for controlling the operation of the valve by applying an electric pulse signal to the electromagnetic switching valve. The electromagnetic switching valve includes a first solenoid that controls the hydraulic pressure of the hydraulic cylinder in the direction of lowering the piston when activated, and a first solenoid that controls the hydraulic pressure of the hydraulic cylinder in the direction of raising the piston when activated. a second solenoid for controlling the piston, and the control circuit selectively applies the electrical pulse signal f to the first and second solenoids and changes the impulse coefficient of the pulse signal to A hydraulic cylinder drive device characterized by variable ascending or descending speed.