JP2582783Y2 - Hydraulic filtration circuit - Google Patents

Description

[Detailed description of the invention]

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hydraulic filter circuit having a filter device.

[0002]

2. Description of the Related Art Generally, in order to remove impurities in a tank provided for a hydraulic circuit, piping of a hydraulic circuit, return piping,
Alternatively, a filter device is interposed in the bypass pipe.

[0003] FIG. 3 shows an example of a hydraulic filtration circuit in which this type of filter device is interposed.
A filter device 104 is interposed in the middle of the main pipe 103 returning from 01 to the tank 102. When the oil returns to the tank 102 after passing through the return main pipe 103,
The cleaning is performed by the filter device 104.

FIG. 4 shows a self-circulation type hydraulic filtration circuit having a dedicated motor and a motor. In this hydraulic filtration circuit, one end 2 of a main pipe 202 is connected to a tank 201.
02A is connected, and the other end 202B of the main pipe 202 is connected to an actuator 204 composed of a cylinder via a direction control valve 203. In addition, main pipe 2
In the middle of 02, a main pump 204A is provided.

[0005] The tank 201 is provided with a dedicated filter device 205. Filter device 205
Is composed of a pipe 206 having both ends connected to the tank 201 to form a closed circuit together with the tank 201, a pump 207 provided in the middle of the pipe 206, and a filter device 208 provided in the middle of the pipe 206. And
Even when the actuator 204 as a load is not operating, the oil in the tank 201 is cleaned by driving the filter device 205.

[0006]

However, in the former hydraulic filter (shown in FIG. 3), the flow rate of the oil flowing through the return main pipe 103 is large. Correspondingly, the capacity of the filter device 104 must be increased, resulting in an increase in cost.

On the other hand, in the latter conventional self-circulation type hydraulic filtration circuit (shown in FIG. 4), in order to purify oil, a dedicated filter having a pump 207 as a driving source as a component is used. The device 205 was newly required, and the device was complicated and expensive.

The present invention has been made in order to solve the above-mentioned problems, and an object of the present invention is to reduce the size of a filter device with a simple configuration even if the flow rate of oil supplied from a tank to a load is large. It is an object of the present invention to provide a hydraulic filtration circuit which can be realized.

[0009]

According to the present invention, there is provided a hydraulic filtration circuit having a filter device for filtering impurities contained in oil in a tank, which is installed in the middle of a main pipe connecting the tank and a load. A variable displacement pump
A dummy load control valve mounted on the downstream side of the variable discharge pump of the main pipe, and a drain port formed in the dummy load control valve and a tank are connected to flow a small amount of oil from the drain port. It is characterized by including a drain pipe and a filter device interposed in the middle of the drain pipe.

[0010]

In the present invention, during operation of the load, oil is sent from the variable displacement pump to the load via the main pipe.

At this time, a part of the oil containing drain flowing from the tank through the main pipe flows from the drain port of the dummy load control valve through the drain pipe, is filtered by the filter device, and the filtered oil flows into the tank. Return.

On the other hand, when the variable discharge type pump is not operated while the load is not operating, oil does not flow through the main pipe, so that the flow rate of the oil flowing from the drain port of the dummy load control valve to the drain pipe. Becomes zero. Therefore, even when the load is not operating, if the variable discharge type pump is operated by giving a command equal to or less than the set pressure of the dummy load control valve, the oil flows through the main pipe. The oil does not flow downstream of the dummy load control valve in the middle of the main pipe, but flows through the drain port to the drain pipe, and returns to the tank. The oil is filtered by the filter device on the way. In this way, while the load is not operating, the oil circulates between the dummy load control valve and the tank while the dummy load control valve forms a dummy load, and the oil is constantly filtered by the filter device. .

[0013]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 and 2 show a hydraulic filtration circuit according to an embodiment of the present invention.

In FIG. 1, reference numeral 1 denotes a tank. One end 2A of a main pipe 2 is connected to the tank 1 and the other end 2B of the main pipe 2 is formed of a cylinder via a first directional control valve 3. One actuator 4 is connected. The oil discharge port 3 </ b> A of the first directional control valve 3 is connected to the tank 1.

A first branch pipe 5 is provided at an intermediate portion of the main pipe 2.
Is connected, and the other end of the first branch pipe 5 is connected to an actuator (not shown). One end of a second branch pipe 6 is connected in the middle of the first branch pipe 5, and the other end of the second branch pipe 6 is connected to a second actuator 8 formed of a cylinder via a second directional control valve 7. It is connected. The oil discharge port 7 </ b> A of the second directional control valve 7 is connected to the tank 1.

Then, the tank 1 and the first
A variable discharge pump 9 is mounted between the directional control valves 3, and the variable discharge pump 9 of the main pipe 2 is mounted.
A dummy load control valve 10 composed of a sequence valve is interposed between the first load control valve 3 and the first directional control valve 3. The control circuit 11 is connected between them.

As shown in FIG. 2, the dummy load control valve 10
Has a valve body 10A, and a poppet valve 10C is slidably received in a hole 10B provided in the valve body 10A. The poppet valve 10C is constantly urged by a compression spring 10D, and a pressing force is applied to a valve seat 10I. Have been. One end of the hole 10B forms a primary port 10E.
And a secondary port 10F is formed. If the poppet valve 10B is equal to or lower than the cracking pressure, the primary port 10E is closed. A small hole 10G is provided in the poppet valve 10B, and the primary port 10E and the drain port 10H are always in communication. Always primary port 1
Oil flows from 0E to the drain port 10H. The poppet valve 10B is normally closed, and when the pressure of the oil on the primary side overcomes the urging force of the compression spring 10D, the poppet valve 10B opens, and the poppet valve 10B is opened.
Movement of the primary port 10E and the secondary port 10F
Is communicated. Oil flows from the primary port 10E to the secondary port 10F.

In the dummy load control valve 10, a small amount of oil is drawn out from the poppet valve 10B to the drain port 10H during the operation of the load (the first actuator 4, the second actuator 8, etc.) and the load is not operated. A small amount of oil is also drained from the poppet valve 10B to the drain port 10B.
H.

The control circuit 11 controls the discharge amount and the discharge pressure of the variable discharge type pump 9. When the swash plate type is adopted as the variable discharge type pump 9, the variable discharge amount The discharge amount and the pressure are controlled by changing the inclination angle of the swash plate by controlling the control cylinder 9B which changes the inclination angle of the swash plate. A control circuit 11 is used to drive the control cylinder 9B.

The dummy load control valve 10 is provided with a drain pipe 12 extending from the drain port 10H of the dummy load control valve 10 to the tank 1. Drain piping 12
, A filter device 13 is interposed.

A bypass circuit 14 for bypassing the filter device 13 is provided in the drain pipe 12, and a check valve 15 is interposed in the bypass circuit 14.
When the filter is clogged, the check valve 15
This is to prevent a rise in the pressure in 2 and prevent malfunction of the dummy load control valve 10 when the filter is clogged at a cracking pressure or less.

The first drain port 17 has the first drain port 1
A drain pipe 19 from 7 to the tank 1 is provided. The drain pipe 12 is connected to a second drain 18. Variable discharge type pump 9 by drain pipe 19
The oil leaking into the tank returns to the tank 1.

The variable displacement pump 9 is provided with a motor 20 for driving. In this embodiment, during operation of the first actuator 4, the second actuator 8, etc., the oil is supplied from the variable discharge pump 9 to the first actuator 4, the second actuator 8, etc. via the main pipe 2. Is sent.

At this time, a part of the oil flowing from the tank 1 through the main pipe 2 flows from the drain port 10H of the dummy load control valve 10 through the drain pipe 12, and the filter device 1
3 and the filtered oil returns into the tank 1.

The drain flow rate is not affected by the flow rate of the oil flowing through the main pipe 2, but is affected by the pressure.
On the other hand, when the variable discharge type pump 9 is not operated while the first actuator 4 and the second actuator 8 are not operating, since the oil does not flow through the main pipe 2, the drain port 10H of the dummy load control valve 10 is not used. The flow rate of oil flowing from the drain pipe 12 to the drain pipe 12 becomes zero.

When the variable discharge pump 9 is not operated, the main pipe 2 is filled with oil, and even if the dummy load control valve 10 is pressurized, the oil flows through the main pipe 2. Not flowing. This is because the variable discharge pump 9 discharges a small amount of oil even when the first actuator 4 and the second actuator 8 are not operating. Enter the pressure command value of. At this time,
Since the poppet valve 10B of the dummy load control valve 10 remains pressed against the valve seat by the compression spring 10D, the oil on the primary side of the dummy load control valve 10 does not flow to the secondary side.

Therefore, even when the first actuator 4, the second actuator 8 and the like are not operating, the variable discharge type pump 9
By inputting and operating a pressure command equal to or less than the cracking pressure of the dummy load control valve 10, oil does not flow to the secondary side of the dummy load control valve 10. A small amount of oil is supplied to the dummy load control valve 10 in the middle of the main pipe 2.
From the drain pipe 10H through the drain port 10H.
And returns to tank 1. Filter device 1 on the way
3 filters the oil. The oil pressure provided by the variable displacement pump 9 is
5 kgf / cm ² below the cracking pressure of
The flow rate of the oil is, for example, about 1 liter / min.

Thus, the first actuator 4,
During the non-operation of the second actuator 8 and the like, the oil circulates between the dummy load control valve 10 and the tank 1 while the dummy load control valve 10 forms a dummy load. It is filtered and the oil is kept clean. During the non-operation of the first actuator 4, the second actuator 8 and the like, the inclination angle of the swash plate is controlled by the command from the control circuit 11 via the control cylinder 9B, A small amount of oil is sent to the main pipe 2.

When the first actuator 4 and the second actuator 8 are not operating, if a pressure command to the variable discharge type pump 9 is input, for example, as 5 kgf / cm ² , the control cylinder 9 B will only adjust the pressure command. The swash plate is tilted, and a corresponding amount of oil is discharged. The variable discharge rate pump 9
And the pressure of the oil between the dummy load control valve 10 and the dummy load control valve 10 increases. The pressure of this oil is detected by the pressure sensor 11A of FIG. 1, and is fed back to the control cylinder 9B so as to become the command pressure. As a result, a small amount of oil is sent from the variable discharge pump 9.

The hydraulic filtration circuit having the above configuration is applied to, for example, a hydraulic circuit that operates a plurality of actuators of an injection molding machine. According to the above configuration, the flow rate of the oil flowing out from the drain port 10H of the dummy load control valve 10 is always a constant low flow rate. Filter device 13 is attached to drain pipe 12
The size of the filter device 13 can be reduced with a simple configuration of mounting the filter device 13, the cost of the filter device 13 can be reduced, and the running cost can be reduced. For example, the power consumption when the first actuator 4, the second actuator 8, and the like do not operate is equal to the power consumption at a load pressure of 5 kgf / cm ² , a flow rate of 1 liter / min, and the mechanical efficiency of the variable discharge pump 9. It is about 0.008 KW.

Since the filter device 13 may be provided in the drain pipe 12 through which a small amount of low-pressure oil flows, a small-sized filter device for low pressure can be selected. Furthermore, when the first actuator 4, the second actuator 8, etc., which are loads, do not operate, the pressure and flow rate commands are given to the variable discharge pump 9, so that the rise at the start of operation of the load can be sharpened.

In this embodiment, a sequence valve is described as an example of the dummy load control valve 10. However, the present invention is not limited to this. For example, a check valve, a flow meter, and the like may be used. Can be mentioned.

[0033]

As described above, according to the present invention, the flow rate of the oil flowing out from the drain port of the dummy load control valve can always be kept at a constant low level regardless of whether the load is operating or not operating. Therefore, a filter device having a capacity corresponding to the flow rate of the minute amount of oil may be provided in the middle of the drain pipe, so that the filter device can be reduced in size with a simple configuration and the cost of the filter device can be reduced. To play.

In addition, there is an effect that a filter device for low pressure can be selected as a filter device in a drain pipe through which a small amount of oil flows.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a hydraulic filtration circuit according to an embodiment of the present invention.

FIG. 2 is a sectional view of the dummy load control valve of FIG. 1;

FIG. 3 is a configuration diagram of a conventional first hydraulic filtration circuit.

FIG. 4 is a configuration diagram of a conventional second hydraulic filtration circuit.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Tank 2 Main piping 9 Variable discharge type pump 10 Dummy load control valve 10H Drain port 12 Drain piping 13 Filter device

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁶ , DB name) F15B 21/04 B01D 35/02 F04B 39/16

Claims (1)

(57) [Scope of request for utility model registration] 1. A hydraulic filtration circuit comprising a filter device for filtering impurities contained in oil in a tank, comprising: a variable discharge type pump mounted in the middle of a main pipe connecting the tank and a load; A dummy load control valve mounted on the downstream side of the variable discharge pump of the main pipe, a drain port connected to a drain port formed in the dummy load control valve and a tank, and a drain for flowing a small amount of oil from the drain port. A hydraulic filtration circuit, comprising: a pipe; and a filter device interposed in a drain pipe.