JPS5847284Y2 - Hydraulic system with bypass circuit - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a hydraulic system equipped with a bypass circuit.

Counterbalance hydraulic circuits using an external pilot system are inherently prone to vibrations, and conventionally vibrations were prevented by increasing back pressure, but this was not desirable due to large energy loss. .

Recently, it has been devised to prevent this vibration by bypassing the inlet and outlet sides of the cylinder. There is a drawback that the position cannot be maintained and therefore the position of the load cannot be maintained.

This invention makes it possible to maintain the position of the piston by linking the main switching valve and the bypass valve.Furthermore, by delaying the timing of the bypass valve, vibrations in the system due to the shock of the main switching valve are also damped by the bypass valve. One example of this is as follows:
This will be explained with reference to the drawings.

In the diagram, 1 is the piston, 2 is the cylinder, 3a button, l
and 3b are external pylont counterbalance valves provided in the middle of pipes 11a and 11b, which will be described later; 4 is a main switching valve; 5 is an oil tank; 6 is a pump; T is connected to the pipes 11a and 11b. 8 is a bypass valve consisting of a switching valve with a throttle provided in the bypass pipe γ;
9 is a variable throttle, 10 is a load mass such as a rotating part of a crane, 11a and 11b are pipes connected to the inlet and outlet sides of the cylinder 20, 12 is a check valve, and 13 is a timing valve.

In a hydraulic system equipped with a bypass circuit configured as shown in the figure, when the main switching valve 4 is switched from the neutral position, the timing valve 13 is linked and switched, and the bypass valve 8 is turned on.
Thus, a damping effect by the throttle of the bypass valve 8 is given to the self-excited vibration system constituted by the load mass 10, the pipes 11raL" and 11b, the capacity of the cylinder 2, and the counterbalance valve 3b.

At this time, since the pilot return hydraulic pressure of the bypass valve 8 mainly passes through the check valve 12, the opening operation of the bypass valve 8 is performed far.

Next, when the main switching valve 4 is returned to the neutral position, the timing valve 13 also returns to the neutral position, and the pilot oil pressure flows through the variable throttle 9, so the bypass valve 8
The load mass 10 is turned off later than the above, and the operation of the load mass 10 is stopped.

Here, the bypass valve 8 is turned off later than the main switching valve 4.
By doing so, the vibration of the system due to the shock when the main switching valve 4 is switched can be damped by the throttle of the bypass valve 8, so that the operating characteristics of the load mass 10 can be improved.

As described above, the hydraulic system equipped with a bypass circuit of the present invention is equipped with a bypass pipe connecting the inlet side and the outlet side of the cylinder in a hydraulic circuit using a counterbalance valve, and
During this bypass line.

Bypass consisting of a switching valve with a throttle that performs the switching opening operation without delay in the switching opening operation of the main switching valve, and the switching closing operation is performed with a timing delay that is more appropriate than the switching closing operation of the main switching valve. a pilot pressure for switching the bypass valve in conjunction with the main switching valve, the valve being actuated by a control signal of the main switching valve to shift the timing when switching the bypass valve; Since it is equipped with a timing valve that generates vibration, and a variable throttle button and check valve that are installed in the pilot line that switches the bypass valve, it is possible to prevent the vibration of an external pilot counterbalance valve, which is generally considered difficult. , and the closing timing of the main switching valve is performed by shifting the timing of closing the bypass valve to damp the vibration of the system including the hydraulic circuit due to the shock caused by the sudden closing of the main switching valve. The effects of this invention are extremely large, such as being able to maintain the position of the load when the door is closed.

[Brief explanation of the drawing]

The figure is an explanatory diagram showing a first embodiment of the present invention. 1...Piston, 2...Cylinder, 3a, 3b...
・External pilot counterbalance valve, 4... Main switching valve, 5... Oil tank, 6... Pump, T... Bypass pipe line, 8... Bypass valve, 9... Variable throttle, 1
0...Load mass, ? 'la,llb...pipeline, 12
...Check valve, 13...Timing valve.

Claims (1)

[Scope of utility model registration request] A hydraulic circuit using a counterbalance valve is provided with a bypass pipe connecting the inlet and outlet sides of the cylinder, and
In this bypass pipeline, the switching operation is performed without delay when the switching operation of the main switching valve is opened, and the switching operation is performed after an appropriate timing delay than the switching operation of the main switching valve. a bypass valve consisting of a switching valve with a throttle, the main switching valve being actuated by a ram signal of the main switching valve to shift the timing when switching the bypass valve; A hydraulic system equipped with a bypass circuit, comprising: a timing valve that generates a pilot pressure for switching the bypass valve; and a variable throttle and check valve provided in a pilot pressure path for switching the bypass valve.