JP2001159470A - Spool-shaped selector valve - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a spool-shaped selector valve, capable of obtaining the sufficient damper effect in the stop of a fluid actuator by preventing a selector valve from being suddenly closed and capable of presenting a delay of the start of the fluid actuator by preventing a delay of the valve opening, in a spool-shaped selector valve for sliding a spool and opening and closing the selector valve, by supplying/discharging fluid to liquid chambers on both ends of the spool. SOLUTION: Control passages for controlling the discharge of fluid in liquid chambers are formed between one of a pair of inlet ports of a spool-shaped selector valve and one of liquid chambers and between the other inlet port and the other liquid chamber, and the control passage is communicated or shut off according to the sliding position of the spool.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a spool type switching valve,
More specifically, in a spool type switching valve that supplies and discharges fluid to the end of the spool and slides the spool to open and close the switching valve, it prevents a sudden closing of the switching valve and has a sufficient damper effect when the fluid actuator stops. The present invention relates to a spool type switching valve which can be suitably used for a brake valve of a fluid motor and the like, in which delay of valve opening is prevented and delay of starting of a fluid actuator is prevented.

[0002]

2. Description of the Related Art A typical example of a spool type switching valve (hereinafter sometimes simply referred to as a switching valve 50) generally designated by reference numeral 50 in FIG. 6 is normally held at a neutral position by return springs 51a and 51b and held. The spool 52 that has been
Switching is performed by selectively supplying and discharging the fluid to a pair of liquid chambers 53a and 53b formed facing each of the two end portions and sliding the same.

The switching valve 50 includes a directional control valve 5 connected to a fluid source 54.
5, inlet-side ports 56a and 56b connected via
Outlet port 58 connected to fluid actuator 57
a and 58b and a tank port 60 connected to the tank 59. The spool 52 has a liquid chamber 53a.
The switching port 62a connecting the inlet port 56a to the inlet port 56a through a check valve 61a that allows only the flow from the inlet port 56a, and the inlet port 56b to the liquid chamber 53b from the inlet port 56b side. A switching flow path 62b connected through a check valve 61b that allows only the flow of the air is formed. In the neutral position of the spool 52 (the position shown in FIG. 6), the communication between the inlet ports 56a and 56b, the outlet ports 58a and 58b, and the tank port 60 is closed.

The switching of the switching valve 50, that is, the spool 5
2 will be described. The spool 52 slides in both axial directions (left and right directions in FIG. 7) with the neutral position interposed therebetween. Therefore, the case where the spool 52 slides from the neutral position in the direction of the liquid chamber 53b (rightward in FIG. 6) will be described, and the case where the spool 52 slides in the opposite direction (leftward in FIG. 6) is applicable. The code is written in parentheses.

(1) Valve opening: When the directional control valve 55 is operated to cause fluid to flow into the inlet port 56a (56b), the fluid flows through the switching flow path 62a (62b) to the liquid chamber 53a (53).
b) and returns the spool 52 to the return spring 51b (51).
It slides in the direction of the liquid chamber 53b (53a) against the urging force of a). At this time, the fluid in the liquid chamber 53b (53a) flows from the switching flow path 62b (62a) to the check valve 61b (61).
a), it is not discharged, but is discharged to the inlet port 56b (56a) through the sliding gap in the outer peripheral portion of the spool 52. The inlet port 56a (56b), the outlet port 58a (58b), and the outlet port 58b (58
a) is communicated with the tank port 60, and the valve is opened. The fluid flowing into the inlet port 56a (56b) flows to the fluid actuator 57 to operate the fluid actuator 57, and the return fluid from the fluid actuator 57 is transmitted to the tank port 60. Flows to

(2) Valve closing: When the supply of fluid to the inlet port 56a (56b) is stopped by operating the direction control valve 55, the fluid in the liquid chamber 53a (53b) is returned to the return spring 51b.
The liquid chamber 5 is controlled by the spool 52 biased by (51a).
3a (53b), the spool 52 is slid in the direction of the neutral position. At this time, the liquid chamber 53a (53b)
Of the check valve 61a from the switching channel 62a (62b).
(61b) and is not discharged, but is discharged to the inlet port 56a (56b) through the sliding gap in the outer peripheral portion of the spool 52. The switching channel 6 is provided in the liquid chamber 53b (53a) on the opposite side.
Fluid flows freely through 2b (62a) and is replenished.
The inlet port 56a (56b), the outlet port 58a (58b), and the outlet port 58b (58
The communication between a) and the tank port 60 is closed and the valve is closed.

(3) Damper function: When the switching valve 50 is closed, the spool 52 is gradually returned to the neutral position by the discharge resistance when the fluid is discharged through the sliding gap of the spool 52 as described above. , Outlet port 58b (5
The communication between 8a) and the tank port 60 is gradually closed. Therefore, the return fluid from the fluid actuator 57 is gradually reduced, and the impact when the operation of the fluid actuator 57 is stopped is reduced. That is, the switching valve 50 has a damper function.

[0008]

The conventional spool-type switching valve 50 of the above-described embodiment has the following problems to be solved.

That is, in the switching valve 50, the smaller the sliding gap at the outer peripheral portion of the spool 52, the more slowly the switching valve 50 is closed, and a greater damper effect is obtained. However, when the sliding gap is reduced, the discharge resistance of the fluid discharged from the liquid chamber 53a or 53b increases. Therefore, a delay occurs when the switching valve 50 is opened, and the supply of the fluid to the fluid actuator 57 is stopped. Operation delays occur late. Therefore, it is necessary for the switching valve 50 to reduce the sliding gap of the spool 52 in order to obtain a large damper effect.
There is a trade-off problem that it is necessary to increase the sliding gap in order to prevent the operation delay of 7.

For this purpose, for example, as shown in FIG. 7, the switching valve 50 is provided with a pair of bypass passages each having check valves 63a and 63b, and when operating the fluid actuator 57, the fluid is supplied to the check valve 63a or 63b. Means are provided so that the fluid can be supplied through the switch 63b and the return fluid from the fluid actuator 57 flows to the switching valve 50 when the fluid actuator 57 is stopped. However, there are problems such as the necessity of an installation space and an increase in cost.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned circumstances, and a technical problem thereof is to provide a spool type switching valve for supplying and discharging fluid to an end of a spool and sliding the spool to open and close the switching valve. The spool can be prevented from suddenly closing to obtain a sufficient damper effect when the fluid actuator is stopped, and a delay in opening the valve can be prevented so that there is no delay in starting the fluid actuator. It is to provide a type switching valve.

[0012]

According to the present invention, as a spool-type switching valve for solving the above technical problem, a spool which is normally biased and held at a neutral position by a return spring is provided at both ends of the spool. A spool-type switching valve that selectively supplies and discharges fluid to a pair of liquid chambers formed so as to face each other, slides, and performs switching operation, wherein each of the liquid chambers has a control flow for controlling discharge of fluid from the liquid chamber. Channels are connected, and each of the control flow paths is conductive when the spool is in the neutral position, and the spool slides from the neutral position toward either one of the pair of liquid chambers. Sometimes, the control flow path connected to the one side liquid chamber is conductive, and when the spool slides from one side of the pair of liquid chambers toward the neutral position, the control flow path is connected to the other side liquid chamber. Connected control flow path is blocked Spool type switching valve is provided, wherein.

In the spool type switching valve according to the present invention, the control chamber for controlling the discharge of the fluid from the liquid chamber is connected to the liquid chamber into which the fluid for sliding the spool is introduced, and the spool is in the neutral position. When sliding toward one of the pair of liquid chambers from the liquid chamber, that is, the control flow path connected to the liquid chamber from which the fluid is discharged is conducted, and the spool is moved from either side of the pair of liquid chambers. When sliding toward the neutral position, the control flow path connected to the other liquid chamber, that is, the liquid chamber from which the fluid is discharged, is shut off. Therefore, when the switching valve is opened, the control flow path is opened to quickly discharge the fluid from the liquid chamber to prevent a delay in opening the valve. When the switching valve is closed, the control flow path is closed to open the control flow path from the liquid chamber. Fluid is gradually discharged to prevent abrupt valve closing, and a sufficient damper effect can be obtained when the fluid actuator is stopped.

In a preferred embodiment, the spool-type switching valve includes a pair of inlet ports, a pair of outlet ports, a tank port, and one of the liquid chambers formed in the spool. One, and the other of the liquid chambers, the other of the inlet-side ports, each having a pair of switching flow paths connected via a check valve that allows only the flow in the direction of the liquid chamber, The control flow path is provided between the one liquid chamber and the one inlet port, and between the other liquid chamber and the other inlet port, respectively, through the switching flow path. When fluid is supplied to one of the liquid chambers and the spool is slid from the neutral position toward the other liquid chamber, one of the inlet ports is connected to one of the outlet ports and the outlet is The other of the side ports is respectively connected to the tank port,
When fluid is supplied to the other liquid chamber through the switching flow path and the spool is slid from the neutral position toward the one liquid chamber, the other of the inlet ports becomes the outlet port. And one of the outlet ports communicates with the tank port.

In a preferred embodiment, the spool-type switching valve has a pair of inlet ports and a pair of outlet ports, and the switching flow path connects each of the inlet ports to each of the liquid chambers via a check valve. Is formed on the spool. A control flow path is formed between each of the liquid chambers and each of the inlet ports. Fluid is alternately connected to and flows into the pair of inlet ports. Therefore, the fluid at the inlet port into which the fluid flows can be guided as fluid for sliding the spool into the liquid chamber, and the fluid discharged from the liquid chamber can be discharged to the inlet port through which the fluid does not flow.

In a preferred embodiment, the control channel is
An annular groove is formed in a slide hole in which the spool slides, and a cutout groove is formed in an outer peripheral portion of the spool so as to extend in an axial direction.

The control channel is formed by an annular groove formed in the spool sliding hole and a cutout groove formed in the outer periphery of the spool. Therefore, the control flow path can be controlled to be opened or closed by the sliding position of the spool.

[0018]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view of a spool-type switching valve constructed in accordance with the present invention;

Referring to FIG.
A spool-type switching valve (hereinafter sometimes simply referred to as a switching valve 2) indicated by, for example, in a hydraulic shovel which is a typical construction machine, is provided with a traveling hydraulic motor 4 which is a fluid actuator and a hydraulic pump 5 which is a fluid source. In the middle of oil passages 5a and 5b connecting the direction control valve 6 for switching control of the discharge oil,
It is provided as a brake valve for the traveling hydraulic motor 4.

The switching valve 2 is normally biased to a neutral position (the position shown in FIG. 1) by a pair of inlet ports 8a and 8b, a pair of outlet ports 10a and 10b, a tank port 12, and return springs 14a and 14b. The spool 16 is provided with a pair of liquid chambers 18a and 18b formed facing both ends of the spool 16, respectively. When the spool 16 is in the neutral position, the inlet ports 8a, 8b,
The communication between the outlet ports 10a and 10b and the tank port 12 is shut off.

A switching flow path 22 is connected to the spool 16 via a check valve 20a which connects the inlet port 8a to the liquid chamber 18a only through the inlet port 8a.
a and the liquid chamber 18b are formed with a switching flow path 22b that connects the inlet port 8b via a check valve 20b that allows only the flow from the inlet port 8b side. Each of the switching flow paths 22a and 22b has one end opened at the end of the spool 16 and the other end opened at the outer periphery of the small diameter portion of the spool 16, and the opening at the outer periphery is opened regardless of the sliding position of the spool 16. 22a is connected to the inlet port 8a,
2b is always in communication with the inlet port 8b.

The switching valve 2 also includes a liquid chamber 18 at the portion between the outer peripheral portion of the end of the spool 16 and the sliding hole 3 of the spool 16.
A control passage 24a connecting the liquid chamber 18b to the inlet port 8b and a control passage 24b connecting the liquid chamber 18b to the inlet port 8b are formed.

Referring to FIGS. 2 and 3 together with FIG. 1, the control channels 24a and 24b are formed symmetrically in the axial direction of the spool 16. Therefore, the description will be made with respect to the control flow path 24a, and the control flow path 24b will be described with the corresponding reference numerals in parentheses. The control flow path 24a (24b) includes an annular groove 26 formed in the slide hole 3 of the spool 16, and a cutout groove 28 formed in the outer peripheral portion of the spool 16 so as to extend in the axial direction. Annular groove 26
The sliding hole 3 of the spool 16 is formed in a range of a predetermined length L inward in the axial direction from the end where the liquid chamber 18a (18b) opens. Two notch grooves 28 are formed on the outer periphery of the spool 16 at intervals of 180 °. Notch groove 28 is
A small-diameter portion of the spool 16 has one end in the longitudinal direction opened in the annular groove 26 in the axial direction by a predetermined length X when the spool 16 is in the neutral position, and the other end opened to the inlet port 8a (8b). It is formed so that it is opened toward.

Therefore, the control flow paths 24a (24b)
When the spool 16 is in the neutral position, the annular groove 26
And the notch groove 28 are open and conductive, and at a position where the spool 16 slides toward the liquid chamber 18b, a length X from the neutral position.
When the control flow path 24b is connected to the liquid chamber 18b and the control flow path 24a is connected to the liquid chamber 18a, the control flow path 24a connected to the liquid chamber 18a is shut off. At the position slid toward the liquid chamber 18a and between the neutral position and the sliding end beyond the length X, the control flow path 24a connected to the liquid chamber 18a is conducted, and the control flow path 24a is connected to the liquid chamber 18b. The connected control channel 18b is shut off.

When the spool 16 slides from the neutral position toward the liquid chamber 18b (to the right in FIG. 1), the spool 1
In the land 16a of FIG. 6, the inlet port 8a starts to open to the outlet port 10a, and the outlet port 10b starts to open to the tank port 12 in the land 16b. The spool 12 slides while increasing the opening area to a sliding end whose end abuts on the inner wall of the liquid chamber 18b. Similarly, when the spool 16 slides from the neutral position in the direction of the liquid chamber 18a (left direction in FIG. 1), the inlet port 8b starts to open to the outlet port 10b in the land 16c of the spool 16, and the outlet port 10a is land 16
The opening to the tank port 12 starts at the part d. The spool 16 further slides while increasing the opening area to a sliding end whose end abuts on the inner wall of the liquid chamber 18a.

The operation of the spool type switching valve 2 as described above will be described with reference to FIG. 4 together with FIGS. The spool 16 slides in both directions between the neutral position and one sliding end and between the neutral position and the other sliding end. The case of sliding between the sliding ends is described, and for the other side, the corresponding reference numerals are given in parentheses.

(1) Opening: When the directional control valve 6 is operated to flow the pressure oil of the hydraulic pump 5 to the inlet port 8a (8b),
The pressure oil flowing into the inlet port 8a (8b) is
2a (22b) flows into the liquid chamber 18a (18b) via the check valve 20a (20b). Port 8 on the other entrance side
The b (8a) is connected to the tank 7 via the direction control valve 6, and the pressure oil of the pump 5 is not supplied to the liquid chamber 18b (18a). The pressure oil flowing into the liquid chamber 18a (18b) slides the spool 16 toward the liquid chamber 18b (18a) against the urging force of the return spring 14b (14a) on the liquid chamber 18b (18a) side. When the spool 16 slides from the neutral position, the inlet port 8a (8b) and the outlet port 10a
(10b) starts to communicate with the outlet port 10b
Communication between (10a) and the tank port 12 starts. Then, the spool 16 slides until its end comes into contact with the inner wall of the liquid chamber 18b (18a) (the state shown in FIG. 4). The hydraulic oil from the pump 5 is guided to the hydraulic motor 4, the hydraulic motor 4 is driven to rotate, and the return oil from the hydraulic motor 4 flows to the tank 7.

In the above-described valve-opening operation of the switching valve 2, the oil, which is the fluid discharged from the liquid chamber 18b (18a) by the sliding of the spool 16, is supplied to the control flow path 24b (2) in a conductive state.
4a), and is released to the tank 7 via the flow direction control valve 6 to the inlet port 8b (8a). Therefore, the resistance of oil discharge from the liquid chamber 18b (18a)
Is significantly reduced as compared with the case where the air is discharged through the sliding gap at the outer peripheral portion, and the inlet port 8a (8b), the outlet port 10a (10b), and the outlet port 10b (10
a) and the opening of the tank port 7 is controlled by the control flow path 24b (2
4a) is much faster than in the case without, and the hydraulic motor 4 can be started properly.

(2) Valve closing: When the supply of the pressure oil to the inlet port 8a (8b) is stopped by operating the directional control valve 6, and therefore the supply to the liquid chamber 18a (18b) is stopped, the return spring Liquid chamber 18 pushed by the urging force of 14b (14a)
The oil a (18b) is blocked from the switching flow path 22a (22b) by the check valve 20a (20b) and is not discharged, and the control flow path 24a (24b) is shut off. It is discharged from the sliding gap of the part. Thus,
The spool 16 returns to the neutral position, and the inlet port 8a (8
The communication between b) and the outlet port 10a (10b) is closed, and the communication between the outlet port 10b (10a) and the tank port 12 is also closed. The supply of pressure oil to the hydraulic motor 4 and the return oil from the hydraulic motor 4
And the rotation of the hydraulic motor 4 stops.

In the above-described closing operation of the switching valve 2, the pressure oil discharged by the sliding of the spool 16 from the liquid chamber 18a (18b) to the neutral position until the spool 16 returns to the neutral position (in detail, Until the neutral position returns to the position X), that is, until the communication between the outlet port 10b (10a) and the tank port 12 is closed, the spool 16 is discharged from the sliding gap on the outer peripheral portion. Therefore, the spool 16 gradually returns to the neutral position due to the discharge resistance,
Return oil from the hydraulic motor 4 is gradually throttled and gradually closed so that a sufficient damper effect can be obtained when the hydraulic motor 4 stops.

(3) Therefore, the control flow paths 24a and 24a
By providing 4b, the sliding gap at the outer peripheral portion of the spool 16 can be reduced without affecting the opening speed of the spool 16, and a desired damper effect can be obtained when the hydraulic motor 4 stops. Further, since the valve can be opened earlier than before, the hydraulic motor 4 can be started appropriately.

(4) By opening the switching valve 2 earlier, as shown in FIG. 7, the directional control valve 55 and the hydraulic motor 57, which are conventionally provided to speed up the supply of pressure oil, are connected. It becomes possible to eliminate the pair of bypass oil passages directly connected and the check valves 63a and 63b.

As described above, the present invention has been described in detail based on the embodiments. However, the present invention is not limited to the above-described embodiments, and can be variously modified or modified within the scope of the present invention. It is.

(1) Control flow path: In the embodiment of the present invention, the control flow paths 24a and 24b are formed by the annular groove 26 of the sliding hole 3 of the spool 16 and the two cutout grooves 2 of the spool 16.
8, the number of the cutout grooves 28 can be set to an appropriate number depending on the size of the switching valve 2 and the like. Further, as shown in FIG.
6 may be an annular groove 34 formed on the entire circumference. further,
The annular groove 26 and the two cutout grooves 28 are positioned so that they can be simultaneously switched to the conductive or cutoff state in the axial direction of the spool 16, but the ends of the two cutout grooves 28 are shifted in the axial direction to control the flow. Roads 24a and 24b
The opening area at the time of conduction and cutoff may gradually change stepwise.

(2) Spool type switching valve In the embodiment of the present invention, the form of the brake valve 2 is shown as a spool type switching valve, but the present invention is limited in its application to this type of brake valve. Not something. That is, the inlet port, outlet port, tank port,
The number, arrangement, etc., and the arrangement of the switching channels and the control channels can be changed as appropriate.

[0036]

According to the spool type switching valve constructed in accordance with the present invention, in the spool type switching valve which supplies and discharges fluid to the end of the spool and slides the spool to open and close the switching valve, the abrupt change of the switching valve is achieved. A spool-type switching valve capable of preventing a valve closing to obtain a sufficient damper effect when the fluid actuator is stopped, and preventing a delay in valve opening to prevent a delay in starting the fluid actuator. Is provided.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view showing a spool type switching valve configured according to the present invention together with an example of connection to peripheral devices.

FIG. 2 is a partially enlarged view of a control flow path of a portion indicated by A in FIG.

FIG. 3 is a partially enlarged cross-sectional view of a control flow path as viewed in a direction indicated by arrows BB in FIG. 1 (a switching flow path is not shown).

FIG. 4 is a sectional view showing the spool type switching valve shown in FIG. 1 in a state where the spool is opened by sliding the spool toward one of the liquid chambers;

FIG. 5 is an enlarged cross-sectional view showing another embodiment of the control flow path as viewed in the direction of arrows BB in FIG. 1 (a switching flow path is not shown).

FIG. 6 is a cross-sectional view illustrating a conventional spool type switching valve together with an example of connection with peripheral devices.

FIG. 7 is a circuit example using a conventional spool type switching valve.

[Explanation of symbols]

 2: Spool type switching valve 3: Sliding hole 8a: Inlet side port 8b: Inlet side port 10a: Outlet side port 10b: Outlet side port 12: Tank port 14a: Return spring 14b: Return spring 16: Spool 18a: Liquid chamber 18b: Liquid chamber 20a: Check valve 20b: Check valve 22a: Switching flow path 22b: Switching flow path 24a: Control flow path 24b: Control flow path 26: Annular groove 28: Notch groove 50: Spool type switching valve 63a: Check valve 63b: Check valve

Claims (3)

[Claims] 1. A spool, which is normally urged to a neutral position by a return spring and held, is slid by selectively supplying and discharging fluid to a pair of liquid chambers formed facing both ends of the spool. In the spool type switching valve to be operated, each of the liquid chambers is connected to a control flow path for controlling discharge of fluid from the liquid chamber, and each of the control flow paths is provided when the spool is at the neutral position. When the spool slides from the neutral position toward one of the pair of liquid chambers, the control flow path connected to the one liquid chamber is conductive, and the spool is Wherein the control flow path connected to the liquid chamber on the other side is shut off when the valve slides toward the neutral position from one side of the pair of liquid chambers. 2. The spool type switching valve includes a pair of inlet ports, a pair of outlet ports, a tank port, and one of the inlet ports in one of the liquid chambers formed in the spool. A pair of switching channels connecting the other of the inlet ports to the other of the liquid chambers via check valves each allowing only the flow in the direction of the liquid chamber; Are provided between the one liquid chamber and the one inlet-side port and between the other liquid chamber and the other inlet-side port, respectively, through the switching flow path. When fluid is supplied to the spool and the spool is slid from the neutral position toward the other liquid chamber, one of the inlet ports is connected to one of the outlet ports and the other is connected to the other of the outlet ports. Are respectively connected to the tank ports, and the fluid is supplied to the other liquid chamber through the switching flow path. When the spool is slid from the neutral position toward the one liquid chamber, the other of the inlet ports is connected to the other of the outlet ports, and one of the outlet ports is connected to the tank port. The spool type switching valve according to claim 1, wherein the spool type switching valve is connected to the spool. 3. The control channel includes an annular groove formed in a slide hole in which the spool slides, and a cutout groove formed in an outer peripheral portion of the spool so as to extend in an axial direction. The spool type switching valve according to claim 1.