JP2899108B2 - Valve device with air release plug - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a valve device provided with an air bleeding plug which is provided in a construction machine such as a hydraulic shovel and is preferably used to bleed air in a hydraulic circuit.

[Conventional technology]

In general, in the case of construction equipment such as hydraulic excavators, if air remains in the hydraulic circuit, the operating oil will deteriorate quickly or the hydraulic equipment will be damaged. It is provided.

In a hydraulic circuit such as a hydraulic excavator that employs a load sensing system, the discharge amount of the hydraulic pump is controlled based on the maximum load pressure among the load pressures of the actuators. In order to prevent the operating speed of each actuator from fluctuating, a pressure compensating valve is provided between the hydraulic pump and each actuator to compensate the operation of each actuator independently. Each of the compensating valves is also provided with the air vent plug.

FIG. 4 shows an example of a hydraulic circuit provided with a pressure compensating valve as a valve device with an air vent plug according to the related art of this type.

In the figure, reference numeral 1 denotes a variable displacement type hydraulic pump constituting a hydraulic source, 2 denotes a hydraulic cylinder as an actuator operated by hydraulic oil from the hydraulic pump 1, and oil chambers 2A and 2B of the hydraulic cylinder 2 are pipes. It is connected to the hydraulic pump 1 and the tank 5 via the lines 3A, 3B, 4A, 4B and the like, and a directional switching valve 6 at a position of 5 ports 3 is provided between the lines 3A, 3B and the lines 4A, 4B. Have been. The directional control valve 6 is provided with an operation lever 6A.
Is switched from the neutral position (a) to the switching positions (b) and (c). At the switching position (b), the hydraulic oil from the hydraulic pump 1 is supplied into the oil chamber 2B of the hydraulic cylinder 2 and the switching position (c) )
As shown, pressure oil is supplied into the oil chamber 2A.

Here, the directional control valve 6 includes variable throttles 7 and 7, and a pilot pipeline 8 is connected downstream of the variable throttle 7. The distal end of the pilot line 8 is connected to the load sensing regulator of the hydraulic pump 1 via a high-pressure selection valve (both not shown) or the like so that the differential pressure across the variable throttle 7 becomes substantially constant. The discharge amount of the hydraulic pump 1 is controlled by a load sensing regulator. A branch pipe 8A is connected in the middle of the pilot pipe 8, and the branch pipe 8A introduces a downstream pressure of the variable throttle 7 into a pressure chamber 16 described later as a load pressure of the hydraulic cylinder 2. It has become.

Reference numeral 9 denotes another pipeline connected to the discharge side of the hydraulic pump 1 at the position of the connection point 10, and the pipeline 9 supplies the hydraulic oil from the hydraulic pump 1 to another actuator (not shown) other than the hydraulic cylinder 2. ), And these actuators are operated by switching operation of a direction switching valve (not shown) or the like. A variable throttle is also provided in the direction switching valve for each of these actuators, and the pressure downstream of the variable throttle (corresponding to the load pressure of each actuator) is the same as the pilot pipeline 8 (see FIG. (Not shown) to be introduced into the load sensing regulator via the high pressure selection valve. In this load sensing regulator, the maximum load among the load pressures of the actuators including the hydraulic cylinder 2 is guided through the high-pressure selection valve, and the discharge pressure of the hydraulic pump 1 corresponds to the differential pressure more than the maximum load pressure. Hydraulic pump 1
Is controlled.

A pressure compensating valve 11 is provided between the directional control valve 6 and the connection point 10 and provided in the middle of the pipe 4A to compensate for the hydraulic cylinder 2 operating independently of other actuators.
Denotes a valve casing constituting the main body of the pressure compensating valve 11, and a spool sliding hole 12B having an annular groove 12A on the outer peripheral side is formed in the valve casing 12, and the spool sliding hole 12B
One side in the axial direction is a screw hole 12D that opens to the outside via an annular step 12C, and the other side in the axial direction is an actuator-side port 12E. Further, the valve casing 12 is formed with a hydraulic pressure source side port 12F which is always in communication with the annular groove 12A, and the port 12F is connected to the middle of the pipe 4A together with the port 12E.

Reference numeral 13 denotes a spool as a valve body inserted into a spool sliding hole 12B of the valve casing 12, and the spool 13 is formed in a closed cylindrical shape, and a radially outward direction is provided on a lid side of the spool 13. A flange 13A that protrudes and regulates the stroke amount of the spool 13 is provided. Further, radial oil holes 13B, 13B are formed in the cylindrical portion of the spool 13 at an axially intermediate portion,
Each of the oil holes 13B communicates and blocks between the ports 12E and 12F of the valve casing 12 via the annular groove 12A. The spool 13 defines a control pressure chamber 14 between the spool 13 and the port 12E, and the pressure on the control pressure chamber 14 side is higher than the pressure on the pressure chamber 16 side by a set pressure of a pressure setting spring 12 described later. It is designed to prevent that.

Reference numeral 15 denotes a lid screwed from the outside into a screw hole 12D of the valve casing 12, and the lid 15 is formed in a closed cylindrical shape from a cylindrical portion 15A and a lid portion 15B, and is provided between the lid 13 side of the spool 13. A pressure chamber 16 communicating with the hydraulic cylinder 2 through a branch line 8A of the pilot line 8 is defined. Reference numeral 17 denotes a pressure setting spring which is a coil spring disposed in the pressure chamber 16 and disposed between the lid 15B of the lid 15 and the spool 13, and the spring 17 causes the spool 13 to always open in the valve opening direction. Energizes at a predetermined set pressure, and directs the pressure oil from the hydraulic pump 1 toward the control pressure chamber 14 so that an oil hole in the spool 13
It is arranged to flow in the direction of arrow A through 13B. The pressure in the control pressure chamber 14 is controlled by the pressure in the pressure chamber.
The valve closes when the pressure in the spring 17 becomes higher than the pressure set in the spring 17, and the stroke amount in the valve closing direction is regulated when the flange 13A comes into contact with the end face of the cylindrical portion 15A of the lid 15. It has become.

Reference numeral 18 denotes an air vent plug screwed into the center of the lid 15B of the lid 15, and the air vent plug 18 has a substantially L-shaped air vent hole opened on the distal end surface and the proximal outer periphery. 18A
The air vent hole 18A is closed by the lid 15B of the lid 15 when the plug 18 is screwed, and is sealed by the O-ring 19. The plug 18 is loosened from the lid 15 when bleeding air from the pressure chamber 16, and the air remaining in the pressure chamber 16 is partially released by opening an air bleed hole 18A. At the same time, it is discharged to the outside of the valve casing 12.

In the prior art configured as described above, the hydraulic pump 1 is driven by a prime mover (not shown), and the direction switching valve 6 is switched from the neutral position (a) to the switching positions (b) and (c). Is supplied into the oil chambers 2B and 2A of the hydraulic cylinder 2, and the hydraulic cylinder 2 is operated.
The load sensing regulator of the hydraulic pump 1 controls the discharge amount of the hydraulic pump 1 so that the discharge pressure of the hydraulic pump 1 becomes higher than the maximum load pressure of each actuator including the hydraulic cylinder 2 by a predetermined pressure.

When the load pressure of the hydraulic cylinder 2 is smaller than the load pressure of the other actuator, the discharge amount of the hydraulic pump 1 is increased substantially according to the load pressure of the other actuator. Will be supplied,
In order to prevent this, a pressure compensating valve 11 is provided in the middle of the pipe 4A, and the hydraulic cylinder 2 is operated independently of other actuators. In this case, the spool 13 of the pressure compensating valve 11 controls the valve casing 12 so that the pressure on the control pressure chamber 14 side is higher than the pressure in the pressure chamber 16 (load pressure of the hydraulic cylinder 2) by the set pressure of the spring 17. Spool sliding hole 12B
And slide between the ports 12F and 12E through the oil hole 13B.
Controls the flow rate of pressure oil flowing in the direction.

In addition, when shipping the hydraulic excavator or the like or performing maintenance, for example, when bleeding air from the pressure chamber 16, the air bleeding plug 18 is loosened from the lid 15 to remove the air bleeding hole 18.
A is opened to the outside, the air remaining in the pressure chamber 16 is jetted to the outside together with a part of the oil liquid, and after the air bleeding operation is completed, the air bleeding plug 18 is screwed into the lid 15 again so as to be tightened. The O-ring 19 seals the air vent hole 19.

[Problems to be solved by the invention]

By the way, in the above-described conventional technology, the pressure chamber 16 of the pressure compensating valve 11 is vertically oriented and the air vent plug 18 is disposed above the pressure chamber 16, so that the pressure chamber 16 is This air can be discharged outside through the air release hole 18A of the air release plug 18.

However, since the pressure compensating valve 11 is disposed in a relatively limited space together with other hydraulic equipment, the pressure chamber 16 may not be able to be oriented in the vertical direction, and the pressure chamber 16 may not be oriented as shown in FIG. When oriented horizontally left and right, the pressure chamber
The air release plug 18 cannot be disposed above the upper portion 16, and the air in the pressure chamber 16 may remain in the hatched portion 20 in FIG. 5 and the air may not be reliably discharged to the outside.

Also, as shown in FIG.
Is used in place of the lid 15 described above,
If the enlarged diameter portion 21C is provided between the cylindrical portion 21A and the lid portion 21B, the air release plug 18 can be provided as shown by a dotted line in FIG.
Can be arranged above the pressure chamber 16. However, in this case, the lid 21 is screwed into the screw hole 12D of the valve casing 12.
The air vent plug 18 also rotates together with the lid 21 when screwed into the cover 21.
Unless the screw hole 21D for the air release plug 18 is formed in C by post-processing, this air release plug 18 cannot be arranged above the pressure chamber 16, which requires difficult processing work and significantly increases the cost. Will be invited.

In particular, in the pressure compensating valve 11, the pressure chamber 16 is set so that the differential pressure before and after the variable throttle 7 built in the directional control valve 6 is set to a predetermined pressure.
A pressure setting spring 17 composed of a coil spring is provided in the
Since the cover 17 is disposed between the cover 15B (21B) of the cover 15 and the cover of the spool 13, it is necessary to make the volume of the pressure chamber 16 relatively large. As the amount of oil to be stored increases, air tends to remain in the pressure chamber 16 and the fifth
When the pressure chamber 16 and the air release plug 18 are arranged in the horizontal direction as shown in the figure, there is a problem that the air release operation becomes difficult.

The present invention has been made in view of the above-described problems of the related art.In the present invention, even when the pressure chamber and the air release plug are arranged in the horizontal direction, the air in the pressure chamber can be discharged to the outside, and the air release operation can be performed. An object of the present invention is to provide a valve device with an air bleeding plug that can be easily performed.

[Means for solving the problem]

The feature of the configuration adopted by the present invention to solve the above-mentioned problem is that a rod-shaped one end side of which is pressed against a lid portion of a lid body by a pressure setting spring and the other end side extends in the spring direction in the pressure chamber. A plurality of spacers extending obliquely from the outer periphery of the intermediate portion in the axial direction toward the center of the end surface on one end side, and guiding the air in the pressure chamber toward the air release hole of the air release plug. That is, the guide groove is formed.

[Action]

With the above configuration, if the air release plug is loosened from the lid of the lid to open the air release hole to the outside, the air in the pressure chamber is directed radially inward from the outer peripheral side of the pressure chamber along each guide groove of the spacer. While being obliquely guided to the outside, the air is discharged to the outside from the air vent hole, so that it is possible to prevent air from remaining on the outer peripheral side of the pressure chamber. Further, the amount of oil in the pressure chamber can be reduced by the rod-shaped spacer, and the possibility of air remaining can be reduced.

〔Example〕

An embodiment of the present invention will be described below with reference to FIG. 1 and FIG. In the embodiment, the same components as those of the prior art shown in FIGS. 4 and 5 are denoted by the same reference numerals, and description thereof will be omitted.

In the drawing, reference numeral 31 denotes a lid defining a pressure chamber 16 between the spool 13 and the lid 31. The lid 31 is used in place of the lid 15 described in the related art, and includes a cylindrical portion 31A and a lid 31B. The space between the two is an enlarged diameter portion 31C. An air release plug 18 is screwed into the center of the lid 31B of the lid 31 to release air from the pressure chamber 16.

Reference numeral 32 denotes a rod-shaped spacer located in the pressure chamber 16 and pressed against the lid 31B of the lid 31 by the pressure setting spring 17.
As shown in FIGS. 2 and 3, the spacer 32 is formed in a large-diameter disk shape at one end, and has a head 32A on which the pressure setting spring 17 is disposed between the spacer 32 and the spool 13. And a shaft portion 32B formed smaller in diameter than the head portion 32A and extending in the pressure setting spring 17 in the axial direction to form a pin shape. The spacer 32 is positioned substantially coaxially in the lid 31 by the pressure setting spring 17, and largely fills the space in the lid 31 to greatly reduce the amount of oil contained in the pressure chamber 16. It is designed to decrease. When the spool 13 slides in the valve closing direction and the oil holes 13B are blocked with respect to the annular groove 12A of the valve casing 12, the spacer 32 does not abut the end face of the shaft portion 32B against the spool 13. Is formed with a predetermined length dimension as described above.

Reference numerals 33, 33,... Denote slit-shaped guide grooves formed by making four cross-shaped cuts in the head 32A and the like of the spacer 32. Each of the guide grooves 33 extends from the outer periphery of the shaft portion 32B to the head. Three
It extends obliquely inward in the radial direction toward the end face of 2A, and the head 32
It merges at the center of the end face of A. And
The converging portion 33A of each guide groove 33 is always in communication with the air vent hole 18A of the air vent plug 18, so that the air remaining on the outer peripheral side of the pressure chamber 16 or the like is moved in the direction of arrow B in FIG. Along the bottom of the air vent hole 18A.

This embodiment has the configuration as described above, and the basic operation of the pressure compensating valve 11 is not particularly different from that of the prior art.

However, in the present embodiment, the spacer 32 is positioned substantially coaxially within the lid 31 by the pressure setting spring 17, and
The space in the pressure chamber 16 is largely filled with 32, and the head portion 32A and the shaft portion 32B of the spacer 32 have the shaft portion 3A.
A substantially cross-shaped guide groove 33, 3 which extends obliquely from the outer periphery of 2B toward the center of the end face of the head 32A and merges at the center of the end face.
Are formed in the shape of a slit. First, the amount of oil contained in the pressure chamber 16 can be reduced by the spacer 32, the amount of air remaining in the pressure chamber 16 can be reduced, and at the same time, during the air bleeding operation, Air can be smoothly discharged to the outside through each guide groove 33.

That is, if the air bleeding plug 32 is loosened to open the air bleed hole 18A to the outside during the air bleeding operation, the air remaining in the pressure chamber 16 flows along each guide groove 33 of the spacer 32 as indicated by an arrow in FIG. In the direction B shown in the drawing, the oil flows into the merging section 33A together with the pressure oil in the pressure chamber 16, and while merging at the merging section 33A, the air vent hole 18A
From the pressure chamber 16 so that the air in the pressure chamber 16 can be effectively discharged to the outside.

Therefore, according to the present embodiment, even when the pressure chamber 16 and the air release plug 18 are disposed in the horizontal direction, the air in the pressure chamber 16 can be reliably discharged to the outside, and the air release operation can be easily performed. . Further, the amount of oil in the pressure chamber 16 is reduced by the spacer 32, and the pressure oil in the pressure chamber 16 passes through the slit-shaped guide grooves 33 from between the pressure setting spring 17 and the spacer 32 during the air bleeding operation. Flow into the air bleed hole 18A, the pressure oil can be throttled by the guide grooves 33 and the like, effectively preventing a large amount of pressure oil from being discharged to the outside together with air during the air bleeding operation. Various effects such as prevention can be achieved.

In the above-described embodiment, the four guide grooves 33, 33,... Having a substantially cross shape are formed in the spacer 32. However, two, three or five guide grooves are formed in the spacer 32 instead. The above-described guide grooves 33, 33,.
The central part 32A of the 32 heads may be radially extended from the center.

In the above-described embodiment, the pressure compensation valve 11 provided for each actuator such as the hydraulic cylinder 2 in the hydraulic circuit or the like employing the load sensing system has been described as an example.
The present invention is not limited to this, and can be applied to various valve devices provided with an air vent plug, such as a pressure control valve and a flow control valve.

〔The invention's effect〕

As described in detail above, according to the present invention, a rod-shaped spool is provided in the pressure chamber, and a plurality of guide grooves for guiding air in the pressure chamber toward the air release hole of the air release plug are formed in the spool. The spacer reduces the amount of oil in the pressure chamber and the amount of residual air.In addition, the air in the pressure chamber can be effectively discharged from the air release hole of the air release plug through each guide groove during air release work. Can be discharged to
At this time, a large amount of pressure oil can be prevented from being discharged outside,
The air bleeding operation can be easily performed.

[Brief description of the drawings]

1 to 3 show an embodiment of the present invention, FIG. 1 is a hydraulic circuit diagram including a pressure compensating valve and the like, FIG. 2 is a left side view of the spacer shown in FIG. 1, and FIG. FIG. 4 is a hydraulic circuit diagram including a pressure compensating valve and the like showing a conventional technique, and FIG. 5 is a hydraulic circuit diagram similar to FIG. 4 showing another conventional technique. 1 ... hydraulic pump, 2 ... hydraulic cylinder (actuator), 5 ... tank, 6 ... directional switching valve, 7 ... variable throttle, 11 ... pressure compensating valve (valve device), 12 ... valve casing, 12B: Spool sliding hole, 12D: Screw hole, 13: Spool (valve element), 16: Pressure chamber, 17: Pressure setting spring,
18 Air vent plug, 18A Air vent hole, 31 Lid, 31A Tube part, 31B Lid, 32 Spacer, 32A
... Head, 32B ... Shaft, 33 ... Guide groove.

──────────────────────────────────────────────────続 き Continuation of the front page (56) References Japanese Utility Model 60-67469 (JP, U) Japanese Utility Model 1-100967 (JP, U) Japanese Utility Model 58-136670 (JP, U) Japanese Utility Model 2 84006 (JP, U) (58) Field surveyed (Int. Cl. ⁶ , DB name) F15B 21/04 F16K 24/04

Claims (1)

(57) [Claims] 1. A valve casing, a valve body slidably inserted into the valve casing, for controlling pressure oil supplied from a hydraulic source to an actuator, and screwed to the valve casing,
A cover having a closed cylindrical shape defining a pressure chamber communicating with the actuator side between the valve body and a valve body disposed between the cover portion and the valve body located in the pressure chamber; A pressure setting spring, and a valve device with an air release plug, which has an air release hole for discharging air remaining in the pressure chamber to the outside of the valve casing, and an air release plug screwed into a lid of the lid. In the pressure chamber, a rod-shaped spacer having one end pressed against the lid of the lid by the spring and the other end extending axially in the spring is provided, and the spacer has an outer periphery at an intermediate portion in the axial direction. A plurality of guide grooves extending obliquely toward the central portion of the one end side end face from the front end and guiding the air in the pressure chamber toward the air vent hole of the air vent plug. Valve device.