JPH0435609Y2 - - Google Patents

Description

[Detailed Description of the Invention] (Field of Industrial Application) The present invention relates to an improvement of a filter device in a closed circuit hydraulic drive circuit.

(Prior Art) A conventional closed circuit hydraulic drive circuit is configured as shown in FIG.

1 is a hydraulic pump that rotates reversibly, and 2 is a hydraulic motor that is operated by supplying hydraulic pressure from the hydraulic pump 1. Hydraulic pump 1 and motor 2 constitute a main closed circuit connected by pipes 3A and 3B.

In the case of such a closed circuit hydraulic drive circuit,
In order to compensate for leakage from the hydraulic pump 1 or motor 2, hydraulic oil from the auxiliary pump 4 is replenished into the low pressure side pipe line 3A or 3B via a check valve 5A or 5B.

By the way, the hydraulic oil from the auxiliary pump 4 is filtered by the filter 6, and the main closed circuit is always replenished with clean hydraulic oil.

(Problem to be solved by the invention) By the way, in such a hydraulic drive circuit,
If an accumulator is provided instead of the auxiliary pump 4 to charge an appropriate boost pressure and supply it to the main circuit, inserting a filter 6 between the accumulator and the check valves 5A and 5B will reduce the pressure during sudden acceleration, etc. Problems with delayed replenishment of hydraulic fluid may occur.

That is, when it is necessary to replenish the main closed circuit with a certain amount of hydraulic oil for a short period of time during sudden acceleration, the hydraulic oil cannot be supplied in a responsive manner due to the resistance pressure loss of the filter 6.

If the capacity of the filter 6 is increased in order to reduce the pressure loss of the filter 6, the overall size will increase, and it is also considered to set the charge pressure of the accumulator high in advance in order to supply hydraulic oil in a responsive manner. However, during normal operation, various parts may be unnecessarily pressurized, which may reduce durability.

The present invention aims to solve such problems.

(Means for solving the problem) The present invention provides a hydraulic drive circuit in which a main closed circuit is formed connecting a hydraulic pump and a hydraulic actuator, and this closed circuit is replenished with pressurized hydraulic oil from an accumulator via a check valve. In this circuit, a circuit is provided to guide leak hydraulic oil from the hydraulic pump and hydraulic actuator to the accumulator, and a filter is interposed between this leak circuit and the accumulator.

(Operation) A portion of the hydraulic oil leaks from the hydraulic pump and actuator, but the leaked hydraulic oil is returned to the accumulator via the leak circuit. When there is a shortage of hydraulic oil in the main closed circuit due to leakage, hydraulic oil from the accumulator is replenished via the check valve. Therefore, the leaked hydraulic oil always flows through the filter to the main closed circuit via the accumulator and check valve, so that the filter always functions properly.

Furthermore, during sudden acceleration, replenishment oil from the accumulator is introduced into the main closed circuit without passing through the filter, so there is no resistance pressure loss caused by the filter at this time, and hydraulic oil can be replenished in a responsive manner.

(Example) FIG. 1 shows an embodiment of the present invention.

A hydraulic actuator 10 is connected to the hydraulic pump 1 via pipes 3A and 3B.

The hydraulic actuator 10 is a reciprocating hydraulic cylinder, and pressure oil is fed into the left and right oil chambers 10A or 10B depending on the rotational direction of the hydraulic pump 1, and the piston 10C reciprocates.

An accumulator 11 is provided to replenish the main closed circuit with hydraulic oil, and a check valve 5 is provided.
It is connected to conduits 3A and 3B via A and 5B.

The accumulator 11 functions as a low-pressure tank, collects leakage hydraulic oil from the hydraulic pump 1 and actuator 10 via circuits 12A and 12B, and replenishes the hydraulic oil in the main closed circuit when it runs out.

and a circuit 12A for recovering leaked hydraulic oil;
A filter 14 is interposed between 12B and the accumulator 11 to collect abrasion powder and the like contained in the leaked hydraulic oil.

The operation of the device configured as above will now be described.

High pressure oil is discharged into the pipe line 3A or 3B depending on the rotational direction of the hydraulic pump 1, thereby operating a cylinder as the hydraulic actuator 10.

When the rotation of the hydraulic pump 1 changes reversibly, the cylinder reciprocates in response.

When the hydraulic oil in the low pressure circuit on the suction side is insufficient, including during rapid acceleration of the hydraulic pump 1, the accumulator 1
The hydraulic oil stored in the pressure vessel 1 is replenished through the check valve 5A or 5B.

In this case, since there is no resistance pressure loss due to the filter 14 between the accumulator 11 and the check valve 5A or 5B, the hydraulic oil is introduced into the main closed circuit with good response.

On the other hand, as the hydraulic pump 1 and actuator 10 operate, a portion of the high-pressure hydraulic oil leaks from sliding parts and the like. This leakage hydraulic oil is in circuits 12A and 12B.
It is returned to the accumulator 11 via .

This is because there is no other place for the leakage hydraulic oil to escape, and the pressure of the leakage hydraulic oil is higher than the set pressure of the accumulator 11, even if it is small. Pass through 14.

Hydraulic oil leaking from the main closed circuit circulates from the filter 14 to the accumulator 11 and is replenished back into the main closed circuit.In this way, the hydraulic oil always flows in one direction, so the filter 14 always flows in one direction. Able to function properly.

In this case, since the drain flow rate of the leaked hydraulic oil is relatively small, the filter 14 may have a small capacity.

(Effects of the invention) As described above, according to the invention, a hydraulic pump and a circuit for guiding leakage hydraulic oil from the actuator are provided to the accumulator, and a filter is interposed between this leak circuit and the accumulator.
Hydraulic oil leaking from the hydraulic pump and actuator always returns to the accumulator through the filter, so that the filter always functions properly.

Furthermore, during sudden acceleration, replenishment oil from the accumulator is introduced into the main closed circuit without passing through the filter, so there is no resistance pressure loss caused by the filter at this time, and hydraulic oil can be replenished in a responsive manner.

[Brief explanation of the drawing]

FIG. 1 is a circuit diagram showing an embodiment of the present invention, and FIG. 2 is a circuit diagram of a conventional example. 1...Hydraulic pump, 3A, 3B...Pipe line, 10
... Hydraulic actuator, 11 ... Accumulator, 12A, 12B ... Leak circuit, 14 ... Filter.

Claims (1)

[Scope of utility model registration request] In a hydraulic drive circuit that constitutes a main closed circuit that connects a hydraulic pump and a hydraulic actuator, and this closed circuit is replenished with pressurized hydraulic oil from an accumulator via a check valve, the hydraulic pump is connected to the accumulator. A hydraulic drive circuit, characterized in that a circuit is provided for guiding leakage hydraulic oil from an actuator, and a filter is interposed between the leakage circuit and an accumulator.