JP2594569B2 - Spool valve - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a means for reducing a fluid force acting on a spool valve.

(Prior Art) A hollow spool is slidably inserted between double sleeves in a spool valve, and a spool port formed in this spool has a fluid passage formed in an outer sleeve and a port formed in an inner sleeve. Are communicated according to the sliding position. The fluid guided from the outside to the fluid passage reaches the inside of the inner sleeve through the spool port and the port, is distributed to several fluid passages through the similar port and the sleeve port, and is then supplied to the outside. These flow rates can be adjusted by sliding the spool. That is, since the cross section of the flow passage between the opening on the upstream side of the spool port and the fluid passage or port facing the opening changes depending on the sliding position of the spool, the flow rate changes using this bottleneck as a control orifice. Further, a jet of fluid is formed downstream of the control orifice having a reduced cross section, and the jet collides with the wall surface of the spool port to exert a fluid force on the spool. It is desirable that this fluid force is as small as possible because it becomes a hindrance to smooth sliding of the spool. For this reason, the spool or sleeve is formed into a special shape, and the momentum of the fluid in the axial direction (spool sliding direction) is increased. Means are known for reducing the change and reducing the velocity component in the axial direction by bringing the flow direction closer to the radial direction.

(Problems to be Solved by the Invention) However, it is not easy to appropriately determine the shape of the spool or the sleeve so that the fluid force is efficiently reduced, and the shape becomes complicated, and it takes time to process and assemble. There was a problem.

An object of the present invention is to reduce the fluid force acting on a spool valve with a simple structure in view of the above problems.

(Means for Solving the Problems) In the present invention, a hollow spool is slidably inserted between double sleeves formed coaxially, and a plurality of fluid passages respectively communicating with the outside are formed in the outer sleeve. The spool is provided with a spool port which is formed in an annular shape on the inner peripheral surface, forms a plurality of ports at predetermined positions of the inner sleeve corresponding to these annular passages, and communicates these ports with the corresponding annular passages, In a pool valve in which an upstream opening of a spool port and a port or an annular passage opposed thereto are formed as a control orifice for controlling flow rate in a bottleneck formed according to a sliding position of the spool, a cross section of the spool port is controlled. It continuously expands in the downstream direction according to the shape of the jet ejected from the nozzle, and each spool port and the corresponding inner sleeve A plurality of ports are arranged at symmetrical positions about the axis of the spool.

(Operation) By continuously expanding the cross section of the spool port downstream of the control orifice in the downstream direction, the jet ejected from the control orifice reaches the downstream without colliding with the wall surface of the spool port. Hard to do. In addition, a force in the center direction acts on the spool due to a difference in fluid pressure generated before and after the control orifice.However, by disposing the port at a symmetric position of the spool axis, this force is offset by a similar force acting from the opposite side. You.

(Embodiment) FIGS. 1 to 3 show an embodiment of the present invention.

FIG. 1 shows a spool valve interposed between an actuator and a hydraulic pump for driving the same.
The inner sleeve 2 is coaxially fixed inside the inside, and a hollow spool 3 is slidably inserted between them. The outer sleeve 1 has an inlet 4 connected to a discharge side of a hydraulic pump (not shown), an outlet 5 for supplying hydraulic oil to an actuator (not shown), and an outlet 6 for returning hydraulic oil to a tank or a suction side of the hydraulic pump. A passage 7 communicating with the inlet 4 at the inner peripheral portion of the outer sleeve 1 and a passage 8 communicating with the outlet 5;
A passage 9 communicating with the outlet 6 is formed in an annular shape facing the spool 3. A plurality of spool ports 10, 11, and 12 are formed in the spool 3 at positions corresponding to the annular passages 7, 8, and 9, respectively. In the inner sleep 2, ports 13, 14, and 15 are formed corresponding to the spool ports 10, 11, and 12, respectively. These ports 13
15 communicate with the hollow portion 16 opened inside the inner sleeve 2.

The spool port 10 is formed so as to increase the cross-sectional area toward the downstream by notching the wall surface of the spool 3 obliquely. This notch 18 is formed on the wall surface 10B of the spool port 10 downstream of the control orifice 17 formed by the wall surface 7A of the annular passage 7 formed on the outer sleeve 1 and the wall surface 10A of the spool port 10, as shown in FIG. You. The angle of the notch 18 is set so as not to interfere with the jet of the hydraulic oil ejected from the control orifice 17. A similar notch 19 is formed in the spool port 12 whose flow direction is opposite to that of the spool port 10 in the opposite direction. On the other hand, the flow rate of the spool port 11 is not controlled, and the cross section of the spool port 11 is formed larger than the port 14 of the inner sleeve 2. In addition, each spool port
A plurality of ports 10 to 12 and corresponding ports 13 to 15 are arranged at symmetrical positions about the axis of the spool 3.

The spool 3 is driven by a driving device 22. In order to collect the hydraulic oil leaked laterally from the gap between the outer sleeve 1 and the inner sleeve 2 and the spool 3, and to prevent the action of pressure on both ends of the sliding spool 3, both ends of the outer sleeve 1 are removed. A drain 20 communicating with the tank is formed.

 Next, the operation will be described.

In this spool valve, hydraulic oil supplied to the inlet 4 from the hydraulic pump is supplied from the annular passage 7 to the spool port.
The hollow portion 16 is filled through the port 10 and the port 13, and supplied to the actuator from the outlet 5 through the port 14 and the spool port 11. The hydraulic oil flow from the outlet 5 to the actuator varies depending on the sliding position of the spool 3 and the load on the actuator.
The oil is collected from the outlet 6 via the spool port 12 and the passage 9 to the suction side of the tank or the hydraulic pump.

In this process, a jet is formed downstream of the control orifice 17 formed by the spool port 10 and the passage 7 in accordance with the opening degree of the control orifice 17, that is, the sliding position of the spool 3. Therefore, the space reaches the hollow portion 16 without colliding with the wall surfaces 10A and 10B of the spool port 10. The spool 3 is urged toward the inner sleeve 2 by the pressure difference generated on both sides of the control orifice 17, and the pressure in the center direction is different from that of the other in the symmetric position across the axis of the spool 3. The pressure acting on the spool port 10 and the port 13 is offset. On the other hand, also in the spool port 12, a control orifice 17 formed between the spool port 12 and the port 15 is provided.
The jet from the tubing reaches the passage 9 without colliding with the wall surface of the spool port 12 due to the notch 19, and the force due to the fluid pressure difference is the same as that acting on the other control orifice 17 located on the opposite side by the same force acting in the opposite direction. Offset. Therefore, the spool 3 is hardly affected by the fluid force in both the axial direction and the center direction regardless of the sliding position and the load of the actuator.
Since the frictional resistance between the spool 3 and the inner and outer sleeves 1 and 2 is small, the spool 3 always slides smoothly with a small force.

FIG. 3 shows a four-way valve in which the present invention is embodied. Two hollow portions 16A and 16B are formed inside the inner sleeve 2, and outlets 5A and 5B correspond to the outer sleeves corresponding to the hollow portions 16A and 16B. The actuator is rotated forward or backward by supplying hydraulic oil to the actuator 21 from one of them. Inlet 4
Communicates with only one of the hollow portions 16A and 16B depending on the sliding position of the spool 3, and the hydraulic oil that drives the actuator 21 returns to the tank or the suction side of the hydraulic pump via the other hollow portion 16A or 16B. I do. Also in this case, notches 18 and 19 are formed in the spool ports 10 and 12, respectively, and these are arranged at symmetrical positions about the axis of the spool 3, so that the same operation as the three-way valve is obtained, and the spool 3 Sliding smoothly with force.

(Effect of the Invention) As described above, according to the present invention, the cross section of the spool port located downstream of the control orifice is continuously enlarged toward the downstream, and the port and the spool port are symmetrically positioned about the axis of the spool. The jet ejected from the control orifice does not collide with the spool port, and not only does the axial fluid force act on the spool,
Minimize the frictional resistance between the spool and the outer or inner sleeve so that the force due to the fluid pressure differential across the control orifice is also offset by a similar force acting on another control orifice located on the opposite side. Can be suppressed. For this reason, the spool slides smoothly with a small force, and the operation and driving of the spool valve become easy.

In addition, the present invention can be implemented easily and at low cost because it is only necessary to devise the sectional shape and arrangement of the spool port with respect to the conventional spool valve.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of a spool valve showing an embodiment of the present invention, FIG. 2 is a cross-sectional view showing an enlarged main part of the same, and FIG. 3 is a cross-sectional view of a spool valve showing another embodiment. 1 ... Outer sleeve, 2 ... Inner sleeve, 3 ... Spool, 7,8,9 ... Circular passage, 10,11,12 ... Spool port, 13,14,15 ... Port, 17 ... Control orifice, 1
8,19 …… Notched.

 ──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-60-234103 (JP, A) JP-A-58-13210 (JP, A) JP-A-62-255604 (JP, A) 30536 (JP, U)

Claims (1)

(57) [Claims] A hollow spool is slidably inserted between coaxially formed double sleeves, and a plurality of fluid passages respectively communicating with the outside are formed in an annular shape on an inner peripheral surface of an outer sleeve. A plurality of ports are respectively formed at predetermined positions of the inner sleeve corresponding to these annular passages, and a spool port for communicating these ports with the corresponding annular passages is provided on the spool. In a spool valve having a control path orifice for controlling flow rate, a spool formed by a port or an annular passage facing the spool in accordance with a sliding position of the spool, a cross section of the spool port is adjusted to a shape of a jet ejected from the control orifice. While continuously expanding in the downstream direction, each spool port and the corresponding port of the inner sleeve are Spool valve, characterized in that a plurality arranged in symmetrical positions as.