JP2001165349A - Directional control valve - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a directional control valve which makes possible to secure a shock absorbing action at times of change-over of a spool from and to a neutral position and to move the spool in very short time under predetermined working oil pressure from the neutral position as well. SOLUTION: In the directional control valve 1 provided with first pilot cap 12 having a pilot chamber 12a against which a end face of the spool 11 is opposing and to which a pilot pressure is introduced, a built-in member 15 is arranged in the pilot chamber 12a and the built-in chamber 15 then contains a space 16 to receive movably a end face of the spool 11 and a orifice 17 to provide the buffering function for the spool 11 to move gradually at the time of change-over to the neutral position wherein the orifice 17 is constitutively communicated to a pilot pressure supply line 18 formed in the first pilot cap 12 through a chamber 12a formed in the built-in member 15.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a directional control which is mounted on various machines including construction machines such as a hydraulic shovel and the like, in which pilot pressure is supplied to an end of a spool via a throttle having a buffer function. About the valve.

[0002]

2. Description of the Related Art Generally, a directional control valve has a main body, a spool slidably provided in the main body, and a pilot control valve, which is mounted on the main body so as to face both ends of the spool and guide pilot pressure. And a pilot cap having a chamber. A spring for returning the spool to the neutral position may be provided inside each of the pilot chambers described above, but a spring for returning the neutral position may be provided only in the pilot chamber of one of the pilot caps. . In any case, the directional control valve has the same external shape in consideration of the common use of members on the manufacturing surface. That is, a pilot cap having pilot chambers of the same shape and dimensions is mounted on both sides of the main body.

A directional control valve having such a general structure has conventionally been provided with a throttle having a buffer function for gently operating the spool when switching from a neutral position to the spool and when switching to the neutral position. Proposed.

FIG. 6 is a sectional view showing a pilot cap portion of this type of conventional directional control valve. As described above, this prior art includes a main body 52, a spool 53 slidably provided in the main body 52,
And a pilot cap mounted to face each of the two ends. In FIG. 6, only one of the pilot caps 54 is shown. A spring for returning the spool 53 to the neutral position is disposed on the other pilot cap (not shown). The pilot cap 54 shown in FIG. 6 has a pilot chamber 54a into which a pilot pressure for operating the spool 53 is guided.

[0005] An adapter 55 having a throttle 56 is screwed into a threaded portion formed at the end of the pilot cap 54. The inside of the adapter 55 is a pilot pressure supply path 57 through which pilot pressure is guided. That is,
The pilot pressure supply path 57 and the pilot cap 5
The fourth pilot chamber 54 a is configured to communicate with the fourth pilot chamber 54 a via a throttle 56.

The conventional directional control valve 5 configured as described above
6, the operation device (not shown) is operated from the neutral state of the directional control valve 51, for example, and the adapter 5 shown in FIG.
When the pilot pressure is supplied to the pilot pressure supply path 57 of No. 5, the pressure oil that has been guided gradually flows through the throttle 56, but in a short time, in fact, in the pilot chamber 54.
a.

When the pressure in the pilot chamber 54a reaches a pressure at which the spool 53 can be operated, the spool 53 slides to the left in FIG. 6 and the directional control valve 51 is switched. Thus, the pressure oil of the main hydraulic pump (not shown) is supplied to the control unit of the hydraulic actuator (not shown) via the direction control valve 51.

As described above, when the spool 53 is switched from the neutral position, the pressure oil is gradually supplied to the pilot chamber 54a via the throttle 56, and the pressure in the pilot chamber 54 gradually becomes the operating pressure of the spool 53. With such an increase, the sudden movement of the spool 53 when switching from the neutral position is suppressed, and the spool 53 is switched gently. As a result, it is possible to supply a stable flow of hydraulic oil with less adverse effect such as hydraulic pulsation to a hydraulic system including a hydraulic actuator (not shown).

For example, when the directional control valve 51 is returned to the neutral state by operating the operating device (not shown) from the state in which the hydraulic actuator (not shown) is driven as described above, the pilot pressure of the adapter 55 is used. Supply path 5
7 communicates with the tank, and the spool 53 shown in FIG.
Slides rightward in FIG. Thus, the pressure oil in the pilot chamber 54a of the pilot cap 54 is guided to the pilot pressure supply path 54 via the throttle 56, and is further returned to the tank. Also at this time, the spool 53 returns to the neutral position relatively slowly due to the buffer function of the diaphragm 56. Therefore, similarly to the above, it is possible to prevent the adverse effect of the sudden movement of the spool 53 on the hydraulic system including the hydraulic actuator (not shown).

[0010]

In the prior art shown in FIG. 6 described above, although the provision of the throttle 56 can provide a good cushioning effect, the pilot cap 54 on the side where no spring is provided is provided. Pilot room 5
The volume of 4a is also set to a relatively large volume that can accommodate the spring. This pilot chamber 54a has a spool 53
To reach a certain working pressure at which the
It takes a very short time, for example, about 0.5 seconds after the operation of the operating device (not shown).

That is, with the large capacity of the pilot chamber 54a, the spool 53 cannot be operated by an operating device (not shown) when the spool 53 is switched from the neutral position.
Responsiveness is not good, and therefore, there is a problem that the operation feeling of the operator tends to be uncomfortable.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned circumstances in the prior art, and has as its object to secure a buffering effect when switching from a neutral position to the spool and when switching to the neutral position. Is to provide a directional control valve which can be moved from a neutral position in a short time.

[0013]

In order to achieve the above object, an invention according to claim 1 of the present application is provided with a spool slidable in accordance with a pilot pressure and a spool provided opposite to an end of the spool. A directional control comprising a pilot cap having a pilot chamber into which the pilot pressure is guided, and a throttle having a buffer function for gently operating the spool when switching from the neutral position to the spool and when switching to the neutral position. In the valve, a built-in member is disposed in the pilot chamber of the pilot cap, and the built-in member has therein a space for movably housing an end of the spool, and the space provided to be connected to the space. It has a configuration having an aperture.

According to the first aspect of the present invention, when the spool is switched from the neutral position and when the spool is switched to the neutral position, the throttle is provided inside the built-in member as in the prior art. Buffer effect can be secured. In addition, a built-in member is arranged in the pilot chamber of the pilot cap, and the end of the spool is made movable in a space inside the built-in member. Since the volume to be removed is smaller than the volume of the pilot chamber of the pilot cap, when the pilot pressure for switching the spool from the neutral position is supplied to the space of the built-in member through the throttle, the pressure in the space is reduced. Can be set to a predetermined operating pressure at which the spool can be moved in a short time.

In order to achieve the above object, the invention according to a second aspect of the present invention is the invention according to the first aspect, wherein the space has a depth dimension substantially corresponding to a stroke limit of the spool. is there.

In order to achieve the above object, a third aspect of the present invention is the invention according to the first or second aspect, wherein the throttle comprises an orifice.

In order to achieve the above object, the invention according to claim 4 of the present application is the invention according to claim 3, wherein a rod is integrally provided at an end of the spool on the orifice side, and And a gap between the orifice and the rod formed by inserting the rod into the orifice.

In order to achieve the above object, the invention according to claim 5 of the present application is characterized in that, in the invention according to claim 1 or 2, the aperture is formed of a choke.

Further, in order to achieve the above object, the invention according to claim 6 of the present application is characterized in that in the invention according to claim 5,
A rod is integrally provided at an end of the spool on the choke side, and the throttle is configured to include a gap between the choke and the rod formed by inserting the rod into the choke. .

In order to achieve the above object, the invention according to claim 7 of the present application is the invention according to any one of claims 1 to 6, wherein the directional control valve is provided in a construction machine. It is characterized by:

[0021]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a directional control valve according to the present invention will be described below with reference to the drawings. 1 and 2 are explanatory views of a first embodiment corresponding to claims 1, 2, 3, and 7 of the present application. FIG. 1 is a circuit diagram showing a hydraulic circuit including the first embodiment, and FIG. FIG. 2 is an enlarged sectional view showing a pilot cap portion of the first embodiment shown in FIG. 1.

The hydraulic circuit shown in FIG. 1 is provided in a construction machine, for example, a hydraulic shovel, and is provided with a directional control valve 1 constituting a first embodiment described later. The direction control valve 1 is switched by a pilot pressure output by reducing the pressure oil of the pilot pump 3 with the operation of the operation device 2. Pilot pump 3
Is maintained at a predetermined pressure by the pilot relief valve 4.

The directional control valve 1 includes a main hydraulic pump 5,
It is arranged between a hydraulic actuator such as a boom cylinder 7. Direction control valve 1 with operation of operation device 2
Is switched to the left or right switching position,
The pressure oil of the main hydraulic pump 5 is supplied to one of the two control units of the boom cylinder 7 via the direction control valve 1, that is, to either the head side or the rod side. The main hydraulic pump 5 is regulated by the main relief valve 6 so that the maximum pressure thereof becomes a predetermined pressure.

The directional control valve 1 constituting the first embodiment
As shown in FIG. 1, a main body 10, a spool 11 slidably provided in the main body 10, and a first pilot cap 12 mounted to face each of both ends of the spool 11. , 2nd pilot cap 1
3 is provided. These first pilot caps 1
Each of the pilot chambers 12a, 1
3a. Of these, a spring 14 for returning the spool 11 to the neutral position is disposed only in the pilot chamber 13a of the second pilot cap 13. The other first
A built-in member 15 is disposed in the pilot chamber 12a of the pilot cap 13.

As shown in an enlarged view in FIG. 2, the built-in member 15 has a space 16 inside which the end of the spool 11 is movably housed, and a diaphragm connected to the space 16, for example, An orifice 17 is provided. That is,
The space 16 of the built-in member 15 and the chamber 16 a communicating with the pilot pressure supply passage 18 formed in the first pilot cap 12 are communicated via the orifice 17. The orifice 17 has a buffering function for gently operating the spool 11 when switching from the neutral position to the spool 11 and when switching to the neutral position.

The space 16 of the above-mentioned built-in member 15 is formed, for example, in a cylindrical shape having an inner diameter slightly larger than the outer shape of the spool 11 and a depth dimension substantially corresponding to the stroke limit of the spool 11. .

The operation of the first embodiment configured as described above is as follows. For example, when the operating device 2 in the neutral state is operated so as to be tilted clockwise in FIG.
The pressure oil of the pilot pump 3 is reduced in pressure, and guided to the pilot pressure supply passage 18 of the first pilot cap 12 as pilot pressure. The pilot pressure is supplied from the pilot pressure supply passage 18 to the room 16 a of the built-in member 15, and further supplied to the space 16 via the orifice 17. This gradually increases the pressure in the space 16 for a short time. During such an operation, the pilot chamber 1 of the second pilot cap 13 shown in FIG.
3a is kept in communication with the tank. When the pressure in the space 16 reaches a predetermined operating pressure at which the spool 11 can be moved, the spool 11
Slides to the left in FIG.

Accordingly, the pressure oil of the main hydraulic pump 5 is supplied to the head side of the boom cylinder 7 via the directional control valve 1, and the oil on the rod side is returned to the tank via the directional control valve 1. The boom cylinder 7 is driven in the extending direction.

When the operating device 2 is returned to the neutral position from such a state, the pilot chamber 12a of the first pilot cap 12 communicates with the tank similarly to the pilot chamber 13a of the second pilot cap 13, as shown in FIG. , The spool 11 starts to move toward the neutral position, a predetermined amount of oil in the space 16 of the built-in member 15 flows out through the orifice 17 into the room 16 a, and further through the pilot pressure supply path 18. Is returned to. As a result, the spool 11 returns to the neutral position. Accordingly, the communication between the head side and the rod side of the boom cylinder 7 and the tank is cut off by the directional control valve 1, and the boom cylinder 7 maintains the above-described extended state.

Conversely, when the operating device 2 in the neutral state is operated so as to be tilted counterclockwise in FIG.
The pressure oil of the pilot pump 3 is reduced, and the pilot chamber 13a of the second pilot cap 13 is used as the pilot pressure.
It is led to. As a result, when the spool 11 moves rightward in FIG. 1 and reaches the stroke end of the spool 11, the right end of the spool 11 comes closest to the orifice 17 shown in FIG.

Accordingly, the pressure oil of the main hydraulic pump 5 is supplied to the rod side of the boom cylinder 7 via the directional control valve 1, and the oil on the head side is returned to the tank via the directional control valve 1. The boom cylinder 7 is driven in a contracting direction.

When the operating device 2 is returned to the neutral position from such a state, the second pilot cap 13
The pilot chamber 13a communicates with the tank similarly to the pilot chamber 12a of the first pilot cap 12, and the spool 11 returns to the neutral position. Therefore, the communication with the tank is interrupted by the direction control valve 1, and the boom cylinder 7 maintains the contracted state.

In the first embodiment configured as described above, when the spool 11 of the direction control valve 1 is switched from the neutral position to the left direction in FIG. The pilot pressure guided to the chamber 16a is supplied to the space 16 through the orifice 17, and is gradually increased within a short period of time as described above. It is moving. Thereby, the spool 11 can be operated slowly when switching from the neutral position.

When the spool 11 is returned to the neutral position from the above-described state, the oil in the space 16 of the built-in member 15 gradually flows out through the orifice 17 into the room 16a, and then flows through the pilot pressure supply path 18. Returned to the tank. This allows the spool 11 to operate slowly when switching to the neutral position.

In particular, in the first embodiment, the first
Since the built-in member 15 is arranged in the pilot chamber 12a of the pilot cap 12, and the end of the spool 11 is made movable in the space 16 inside the built-in member 15, the volume of the space 16 of the built-in member 11, that is, The volume near the right end of the spool 11 shown in FIGS.
The volume is smaller than the volume. Thereby, when the pilot pressure for switching the spool 11 from the neutral position to the left direction in FIGS. 1 and 2 is supplied to the space 16 of the built-in member 15 via the orifice 17, the small volume as described above is obtained. Accordingly, the pressure in the space 16 can be set to a predetermined operating pressure at which the spool 11 can be moved in a short time, for example, in about 0.1 second. Thereby, good responsiveness of the spool 11 to the operation of the operating device 2 at the time of switching from the neutral position of the spool 11 can be obtained, and excellent operability can be secured.

FIG. 3 is a sectional view showing a main part of a second embodiment corresponding to claim 5 of the present application. In the second embodiment, the pilot chamber 12a of the first pilot cap 12
Is provided with a slot-shaped choke 27 as a diaphragm. That is, the space 26 of the built-in member 25 communicates with the room 27 a connected to the pilot pressure supply passage 18 formed in the first pilot cap 12 via the choke 27.

FIG. 4 is a sectional view showing a main part of a third embodiment corresponding to claim 4 of the present application. In the third embodiment, the pilot chamber 12a of the first pilot cap 12
Is provided with an orifice 17 as in the first embodiment shown in FIGS. 1 and 2 described above, but can be inserted into the orifice 17 at the right end of the spool 11 shown in FIG. The rod 30 is provided integrally. In the third embodiment, an aperture is formed by the gap 31 between the orifice 17 and the rod 30.

FIG. 5 is a sectional view showing a main part of a fourth embodiment corresponding to claim 6 of the present application. In the fourth embodiment, the pilot chamber 12a of the first pilot cap 12
3 is provided with a choke 27 similarly to the above-described second embodiment shown in FIG. 3, but is provided at the right end of the spool 11 shown in FIG. 5 in the third embodiment shown in FIG. As in the embodiment, a rod 40 that can be inserted into the choke 27 is provided integrally. In the fourth embodiment,
An aperture is formed by the gap 41 between the choke 27 and the rod 40.

In the above-described second to fourth embodiments,
The spool 1 is moved by a choke 27 provided on the built-in members 25 and 15 or a throttle formed by gaps 31 and 41.
1 A buffering action can be ensured when switching from the neutral position and when switching to the neutral position. Also, the built-in member 25,
Since the volume of the space portions 26 and 16 of the first pilot cap 12 is smaller than the volume of the pilot chamber 12a of the first pilot cap 12, when the spool 11 is switched from the neutral position, the pressure in the space portions 26 and 16 is reduced. Within a short time of about 0.1 second, the operating pressure can be set to a predetermined value at which the spool 11 can be moved, and the same operation and effect as in the first embodiment can be obtained.

[0040]

According to the invention of each claim of the present invention,
By the throttle provided inside the built-in member arranged in the pilot chamber of the pilot cap, a buffering action can be secured at the time of switching from the neutral position to the neutral position and at the time of switching to the neutral position, as in the prior art. The spool can be moved within a short period of time from the neutral position, that is, within a fraction of a short time compared to the prior art. Therefore, the spool can be moved with respect to the operation of the operating device when the spool is switched from the neutral position. Good responsiveness can be obtained, and excellent operability can be ensured as compared with the prior art.

[Brief description of the drawings]

FIG. 1 is a circuit diagram showing a hydraulic circuit including a first embodiment of a directional control valve of the present invention.

FIG. 2 is an enlarged sectional view showing a pilot cap portion of the first embodiment shown in FIG. 1;

FIG. 3 is a sectional view showing a main part of a second embodiment of the present invention.

FIG. 4 is a sectional view showing a main part of a third embodiment of the present invention.

FIG. 5 is a sectional view showing a main part of a fourth embodiment of the present invention.

FIG. 6 is a sectional view showing a pilot cap portion of a conventional directional control valve.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Direction control valve 2 Operating device 3 Pilot pump 4 Pilot relief valve 5 Main hydraulic pump 6 Main relief valve 7 Boom cylinder 10 Main body 11 Spool 12 First pilot cap 12a Pilot chamber 13 Second pilot cap 13a Pilot chamber 14 Spring 15 Assembly member Reference Signs List 16 space 16a room 17 orifice (throttle) 18 pilot pressure supply path 25 built-in member 26 space 27 choke (throttle) 27a room 30 rod 31 gap (throttle) 40 rod 41 gap (throttle)

Claims (7)

[Claims] 1. A spool slidable in accordance with a pilot pressure, a pilot cap provided opposite to an end of the spool and having a pilot chamber to which the pilot pressure is guided, and a spool from a neutral position of the spool. When switching,
And a throttle having a buffering function for gently operating the spool when switching to the neutral position.A directional control valve comprising: a built-in member disposed in the pilot chamber of the pilot cap; A directional control valve, comprising: a space for movably housing an end of the spool; and the restrictor connected to the space. 2. The directional control valve according to claim 1, wherein said space has a depth dimension substantially corresponding to a stroke limit of said spool. 3. The directional control valve according to claim 1, wherein the throttle is an orifice. 4. An orifice is provided integrally with an end of the spool on the orifice side, and the throttle is formed by a gap between the orifice and the rod formed by inserting the rod into the orifice. 4. The directional control valve according to claim 3, wherein: 5. The directional control valve according to claim 1, wherein the throttle is a choke. 6. A rod is integrally provided at an end of the spool on the choke side, and the throttle is formed by a gap between the choke and the rod formed by inserting the rod into the choke. 6. The directional control valve according to claim 5, wherein: 7. The directional control valve according to claim 1, wherein the directional control valve is provided in a construction machine.