JPS6139551B2 - - Google Patents

Description

[Detailed Description of the Invention] (Industrial Application Field) The present invention limits the flow rate of pressure oil flowing into an outflow port when a control valve connected to the upstream side of a hydraulic circuit is operated simultaneously. Regarding directional control valves.

(Prior art) A large number of various control valves such as directional control valves are connected in parallel or in series in the hydraulic circuit of a hydraulic system of a hydraulic system widely used in various industrial machines including construction machinery. , actuators such as hydraulic cylinders connected to each of these control valves can be freely controlled. In such hydraulic systems, so-called complex operations in which two or three actuators are controlled simultaneously are not uncommon, and are rather common operations except for extremely simple operations.

By the way, in the case of industrial machines such as power shovels, when an actuator connected to the upstream side of the hydraulic circuit and an actuator connected to the downstream side are driven at the same time, depending on the content of the work, the downstream side may There are cases where it is desired to control the actuator so that the operating speed of the actuator on the upstream side is always smaller than that of the actuator on the upstream side.

Conventionally, in order to meet such requirements, a restriction (fixed orifice) was installed in a predetermined oil path formed in the housing of the switching valve to adjust the flow rate, or a hydraulic circuit was established independently for each control system. They dealt with it by forming.

(Problems to be Solved by the Invention) However, in the former case, the structure of the switching valve becomes complicated and the design of the valve itself often needs to be changed, making the switching valve very expensive. The hydraulic circuit becomes complicated and the number of circuit components such as control valves used increases, resulting in problems such as the equipment becoming very expensive.

The present invention was made in view of the above problems, and
The purpose is to provide a directional control valve that can achieve a desired function by simply changing a part of an existing valve, and can simplify the structure of a hydraulic circuit.

(Means for Solving the Problems) In order to achieve the above object, the present invention has a neutral port molded in the main body, which is arranged so that the central part is on the downstream side and both sides are on the upstream side, and the spool has an axial through hole. and a radial through hole, an end of the axial through hole on the spool center side communicates with the radial through hole, and the radial through hole is located outside of the upstream side of the neutral port formed in the housing. and is communicated with the upstream side of the neutral port by displacement of the spool, and the other end of the axial through hole is always communicated with the cylinder port via a check valve that allows pressure oil to flow from the radial through hole side, A constricted portion is formed between the pump port and the cylinder port on the outer periphery of the spool, one end of the constricted portion is always in communication with the cylinder port, and the other end is configured to communicate with the pump port by displacement of the spool. did.

(Example) An example of the present invention will be described below based on the accompanying drawings.

1 and 2 are cutaway side views of a directional control valve according to the present invention, and FIG. 3 is a hydraulic circuit diagram of a hydraulic system.

As shown in FIG. 1, a hole 1b is provided through the housing 1a of the directional control valve 1.
A spool 2 is slidably inserted into the spool 2. Further, in the housing 1a, inflow and/or outflow ports A, B, a pump port P, a tank port T, and a neutral port N are formed which communicate with the hole 1b. The pump port P communicates with an oil passage Pa formed in the housing 1a, and the oil passage Pa is connected to an oil passage 30 on the hydraulic pump 40 side via an oil passage 20 as shown in FIG. . Also, tank port T
The oil passage is also connected to an oil passage not formed in the housing 1a, and the oil passage is connected to an oil passage 31 on the tank 50 side via an oil passage 21 shown in FIG. still,
A relief valve 60 is connected to the oil passage 30 in parallel with the pump 40.

By the way, the neutral port N is connected to the housing 1a.
It is divided into three ports N ₁ , N ₂ , N ₃ that communicate with each other within the housing 1a, and the two ports N ₁ and N ₂ on both sides are neutral ports on the upstream side, and these are formed in the housing 1a. The neutral port of the control valve 70 connected to the upstream side of the directional control valve 1 is connected to a neutral port on the downstream side of the control valve 70 via an oil passage and an oil passage 32 shown in FIG. Further, the central port _N3 is a neutral port on the downstream side, and is connected to an oil passage (not shown) formed in the housing 1a and an oil passage 33 shown in FIG. 3. Note that a hydraulic cylinder 90 to be controlled is connected to the control valve 70.

A check valve 3 is disposed at the pump port P in the housing 1a, and its valve body 3a closes a communication portion Pb between the pump port P and the oil passage Pa by the pressing force of a spring 3b. . and,
When the force acting on the valve body 3a based on the oil pressure in the oil passage Pa increases beyond the pressing force of the spring 3b, the valve body 3a is pushed up against the spring 3b, and pressure oil flows into the pump port P. It's becoming like that.

The two ports A and B communicate with the oil chambers S ₁ and S ₂ of the hydraulic cylinder 80 via oil passages 25 and 26, respectively, as shown in FIG. Note that when one of these ports A and B serves as an outflow port, the other port serves as an inflow port.

Further, the spool 2 is inserted into the hole 1b of the housing 1a.
Lands 2a, 2b, and 2c are formed at predetermined locations, respectively. The lands 2a and 2b close the pump port P when the spool 2 is in the neutral position shown in FIG. 1, and the land 2c is located at the center of the downstream neutral port _N3 . The outer circumferential surface 2f of the end of the land 2a on the port A side is notched to a predetermined size, and a constricted portion 4 is formed between the land 2a and the inner wall surface of the hole 1b. One end of this throttle part 4 is always in communication with port A regardless of the position of spool 2, and the other end is cut off from communication with pump port P when spool 2 is in the neutral position shown in FIG. When it moves in the direction of arrow E and reaches the "pull" position, it communicates with the pump port P, as shown in FIG. 2, so that the pump port P and port A are communicated with each other.

Two holes 5 and 6 are formed concentrically at the axial center position from the land 2a to the end 2d of the spool 2, and the bottom end of the hole 5 has a plurality of holes drilled radially in the radial direction. It is opened at a predetermined position on the outer peripheral surface of the land 2a via the land 2a. The holes 6 are a plurality of holes 6 radially bored in the peripheral wall near the bottom end.
It is opened at a predetermined position on the outer peripheral surface of the spool through a. When the spool 2 is in the neutral position shown in FIG. 1, the hole 5a is closed by the inner wall surface of the hole 1b, and the hole 6a faces the port A.

A check valve 7 is disposed within the hole 6, and a hole 8a is formed at the axial center of the valve body 8 of the check valve 7. The bottom end of this hole 8a opens to the outer peripheral surface of the valve body 8 through a plurality of holes 8b formed radially in the radial direction. One end of the spring 9 is fitted into the hole 8a of the valve body 3 and comes into contact with the stepped portion 8c, and the other end is attached to the end face of a screw 10 screwed into the threaded portion of the open end of the hole 6 of the spool 2. The valve body 8 is pressed against the stepped portion 6b between the holes 5 and 6, thereby closing these holes 5 and 6.

The spool 2 is freely moved in the direction of the arrow E or F within the hole 1b of the housing 1 as described above by operating the operating lever 11 (FIG. 3) attached to the end portion 2e. When the operating lever 11 is not operated, the spool 2 is positioned at the neutral position shown by the spring 12 (FIG. 3).

In this configuration, when the spool 2 is in the neutral position as shown in FIGS. 1 and 3, the pump port P is closed by the lands 2a and 2b of the spool 2, and the pump port P is closed by the lands 2a and 2b of the spool 2, and the pump port Communication is cut off. The pressure oil flowing into the directional switching valve 1 from the oil passage 32 flows out into the oil passage 33 through the neutral port N, and the hydraulic cylinder 80 is unloaded. When the spool 2 is pulled in the direction of the arrow E by operating the operating lever 11, the directional control valve 1 is switched to the position _1A shown in FIG. Pump port P and port A are connected by the throttle part 4.
(See Figure 2). At the same time, communication between upstream neutral ports N ₁ and N ₂ and downstream neutral port N ₃ is cut off, communication between upstream oil passage 32 and downstream oil passage 33 is cut off, and port B and tank The spool 2 is communicated with the port T through the small diameter portion 2h of the spool 2. In this case, port A becomes an outflow port and port B becomes an inflow port.

Therefore, the pressure oil flowing into the upstream neutral port _N1 from the oil passage 32 flows into the hole 5 through the hole 5a,
The valve body 8 of the check valve 7 is pushed against the spring 9 toward the right in FIG.

On the other hand, the pressure oil flowing from the pump 40 through the oil passages 30 and 20 into the oil passage Pa in the housing 1a pushes up the valve body 3a of the check valve 3 against the spring 3b to open the check valve 3, as shown in FIG. , flows into the outflow port A from the pump port P through the constriction part 4 and the small diameter part 2g. At this time, the flow rate of the pressurized oil is limited to a predetermined amount by the throttle section 4. In this way, the entire amount of pressure oil flows from the upstream neutral port _N1 and the pump port P to the outflow port A.

The pressure oil flowing out from the outflow port A is supplied to the oil chamber _S1 of the hydraulic cylinder 80 through the oil passage 25, and the hydraulic cylinder 80 is driven. The return oil from the hydraulic cylinder 80 flows into the inflow port B through the oil passage 26 and is returned to the tank 50 via the tank port T and the oil passages 21 and 31. In this way, the hydraulic cylinder 80 is driven at a speed corresponding to the supplied hydraulic flow rate.

If the upstream control valve 70 is operated simultaneously while the directional control valve 1 is being operated in this way, the pressure oil from the oil passage 32 to the upstream neutral port N ₁ is cut off, and the flow from the neutral port N ₁ to the outflow port A is interrupted. Pressure oil will no longer flow to the pump port P, and only pressure oil will flow from the pump port P. However, the flow rate of pressurized oil flowing from the pump port P to the port A is restricted by the restrictor 4, and is significantly reduced compared to the above. Therefore, the flow rate of pressure oil supplied to the hydraulic cylinder 80 decreases, and the speed of the hydraulic cylinder 80 decreases accordingly. Therefore, when the upstream control valve 70 and the directional switching valve 1 are operated simultaneously, the speed of the hydraulic cylinder 80 connected to the directional switching valve 1 is necessarily slowed down, and the hydraulic cylinder 80 is not controlled by the upstream control valve 1. The hydraulic cylinder 90 driven by the valve 70 can be driven at a desired speed. Of course, when the operation of the upstream control valve 70 is completed and the control valve 70 is switched to the neutral position and pressure oil is supplied to the oil passage 32, the hydraulic cylinder 80 connected to the directional control valve 1 returns to the original speed. do.

When the spool 2 is pushed in the direction of arrow F in the opposite direction to that described above by operating the operating lever 11, the directional control valve 1 is switched to the position 1B shown in FIG. 3, and its pump port P and port B are communicated. Pump port P and port A communicate with land 2 of spool 2.
port A and tank port T.
are communicated via the small diameter portion 2g of the spool 2,
Upstream neutral ports N ₁ and N ₂ and downstream neutral ports
Communication with N ₃ is blocked by lands 2c and 2b. Note that in this switching position, port B becomes an outflow port and port A becomes an inflow port.

Then, the entire amount of pressure oil from the pump port P flows into the port B through the small diameter portion 2h of the spool 2, flows into the hydraulic cylinder 80 via the oil passage 26, and drives the hydraulic cylinder 80 in the opposite direction to the above-mentioned direction. do. The return oil from the hydraulic cylinder 80 flows into the port A via the oil passage 25, and flows into the tank port T through the small diameter portion 2g of the spool 2. In this switching position, the flow rate of the pressure oil flowing out from port B is completely unrelated to the pressure oil in the upstream neutral port _N2 , and therefore
Even if 0 is operated simultaneously, the speed of the hydraulic cylinder 80 connected to the directional control valve 1 does not change at all.

In this embodiment, a check valve 7 and a throttle part 4 are provided on one side of the spool 2, so that when the upstream control valve 70 is simultaneously operated during the "pull" operation of the spool 2, the pump port P is connected to the port A. Although the case has been described in which the flow rate of pressure oil to the spool 2 is restricted, the present invention is not limited to this, and the check valve 7 and the throttle part 4 are provided on both sides of the spool 2, so that the spool 2 can be pulled or pushed. The flow rate of pressure oil flowing from pump port P to port A or B may be restricted for operation in any direction.

Incidentally, the size of the throttle portion 4 may be set in accordance with the driving speed of the actuator during the compound operation.

(Effects of the Invention) As explained above, according to the present invention, the neutral port formed in the main body is arranged so that the central part is on the downstream side and both sides are on the upstream side, and the spool has an axial passage hole and a radial passage. the spool center side end of the axial through hole communicates with the radial through hole, and the radial through hole is located outside the upstream side of the neutral port formed in the housing, and the radial through hole is located outside the upstream side of the neutral port formed in the housing. Due to the displacement, the neutral port is communicated with the upstream side, and the other end of the axial through hole is always communicated with the cylinder port via a check valve that allows pressure oil to flow from the radial through hole side, and the outer periphery of the spool is A constriction part is formed between the pump port and the cylinder port, and one end of the constriction part always communicates with the cylinder port, and the other end communicates with the pump port by displacement of the spool. When two control valves are operated simultaneously, the speed of the actuator connected to the directional control valve can always be slowed down, and the upstream and downstream actuators can be set to the desired speed balance during combined operation. . Moreover, the configuration is simple because it is only necessary to provide a check valve and a throttle part on the spool without making any major changes to the existing valve, which has excellent effects such as simplifying the configuration of the hydraulic circuit. .

[Brief explanation of the drawing]

1 and 2 are longitudinal sectional views showing one embodiment of the directional control valve according to the present invention, and FIG. 3 is a hydraulic circuit diagram of the hydraulic system. 1... Directional switching valve, 2... Spool, 3, 7...
...Check valve, 4... Throttle section, 5, 6... Hole, 1
0...Bolt, 11...Operation lever, 20,2
1, 25, 26, 30-33... oil road, 40...
Pump, 50... Tank, 60... Relief valve, 70... Control valve, 80, 90... Hydraulic cylinder, P... Pump port, A, B... Cylinder port, N... Neutral port, T... tank port.

Claims (1)

[Claims] 1 A neutral port formed in the main body is arranged so that the central part is on the downstream side and both sides are on the upstream side, an axial through hole and a radial through hole are formed in the spool, and the spool central part of the axial through hole is arranged. A side end communicates with the radial through hole, and the radial through hole is located outside the upstream side of the neutral port formed in the housing and communicates with the upstream side of the neutral port by displacement of the spool, and the radial through hole communicates with the upstream side of the neutral port formed in the housing. The other end of the hole is always in communication with the cylinder port via a check valve that allows pressure oil to flow from the radial passage side, and a constriction is formed between the pump port and the cylinder port on the outer periphery of the spool. , a directional control valve in which one end of the throttle portion is always in communication with the cylinder port, and the other end is in communication with the pump port by displacement of the spool.