JPH04203509A - Valve system with air bleeding plug - Google Patents

Abstract

PURPOSE:To facilitate air bleeding work by forming a guide groove for guiding air remaining inside a pressure chamber to an air bleeding hole of an air bleeding plug on the abutment side of a spacer against a cap portion, the spacer being pushed against the cap portion by a spring. CONSTITUTION:Inside a pressure chamber 16 where a valve casing 12 is defined inside a cap body 31, there is provided a spacer 32 pushed against a cap portion 31B of the cap body 31 by a spring 17. The spacer 32 is formed of a head portion 32A and shaft portion 32B on a cap portion 31B side, for reduction of an oil quantity inside the pressure chamber 16. A guide groove 33 is formed which extends slantwise from the outer periphery of the shaft portion 32B toward the center of an end surface of the head portion 32A and meets together in the center of the end surface. Consequently, air remaining inside the pressure chamber 16 can be discharged from an air bleeding hole 18A of an air bleeding plug 32. Therefore, the oil quantity inside the pressure chamber 16 can be reduced, and air discharging work can be facilitated.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention is provided in a construction machine such as a hydraulic excavator,
Related to a valve device with an air bleed plug that is suitably used to bleed air in a hydraulic circuit [Prior art] In general, in construction machinery such as hydraulic excavators, if air remains in the hydraulic circuit, it can cause deterioration of the hydraulic fluid. To prevent this from happening too quickly or causing damage to hydraulic equipment, valve devices that require air bleeding are provided with air bleeding plugs.

In addition, in hydraulic circuits such as hydraulic excavators that employ load sensing systems, the discharge amount of the hydraulic pump is controlled based on the maximum load pressure among the load pressures of each actuator. In order to prevent fluctuations in the operating speed, etc. of each actuator, the hydraulic pump and each actuator.

A pressure compensating valve is provided between each actuator and the actuator to independently compensate for the operation of each actuator, and each of these pressure compensating valves is also provided with the air bleed plug.

Therefore, FIG. 4 shows an example of a hydraulic circuit provided with a pressure compensating valve as a valve device with an air bleed plug according to this type of prior art.

In the figure, 1 is a variable displacement hydraulic pump constituting a hydraulic source, 2 is a hydraulic cylinder as an actuator operated by pressure oil from the hydraulic pump 1, and oil chambers 2A and 2B of the hydraulic cylinder 2 are pipes. Roads 3A, 3B, 4A, 4
The hydraulic pump 1 and the tank 5 are connected to the hydraulic pump 1 and the tank 5 via the pipes 3A and 3B, and a directional switching valve 6 with 5 ports and 3 positions is provided between the pipes 3A and 3B and the pipes 4A and 4B. The directional switching valve 6 is switched from the neutral position (a) to the switching positions (b) and (c) by the operation lever 6A, and in the switching position (b), the pressure oil from the hydraulic pump 1 is transferred to the oil in the hydraulic cylinder 2. In the switching position (c), pressure oil is supplied into the oil chamber 2A as shown in the figure.

Here, the directional control valve 6 incorporates a variable throttle 7.7, and a pilot line 8 is connected to the downstream side of the variable throttle 7. The tip side of the pilot pipe 8 is connected to the load sensing regulator of the hydraulic pump 1 via a high pressure selection valve (none of which is shown), etc., so that the differential pressure before and after the variable throttle 7 is almost constant. The discharge amount of the hydraulic pump 1 is controlled by a load sensing regulator. Further, a branch pipe 8A is connected in the middle of the pilot pipe 8, and this branch pipe 8A is configured to introduce the downstream pressure of the variable throttle 7 into the pressure chamber 16, which will be described later, as the load pressure of the hydraulic cylinder 2. It has become.

Reference numeral 9 denotes another pipe line connected to the discharge side of the hydraulic pump 1 at the connection point 10, and the pipe line 9 supplies pressure oil from the hydraulic pump 1 to an actuator other than the hydraulic cylinder 2 (not shown). ) and connect these actuators to directional valves (
(not shown). Further, a variable throttle is also provided on the directional control valve for each of these actuators, and the pressure on the downstream side of the variable throttle (corresponding to the load pressure of each actuator) is controlled through a pilot pipe similar to the pilot pipe 8 (see Fig. (not shown) to the load sensing regulator via a high pressure selection valve. In this load sensing regulator, the maximum load among the load pressures of each actuator 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 above this maximum load pressure. The discharge amount of the hydraulic pump 1 is controlled so that the pressure increases by the same amount.

Reference numeral 11 denotes a pressure compensation valve 12 located between the directional control valve 6 and the connection point 10 and provided in the middle of the pipe 4A in order to compensate for the hydraulic cylinder 2 operating independently of other actuators. indicates a valve casing constituting the main body of the pressure compensating valve 11, and inside the valve casing 12 there is an annular groove 1 on the outer circumferential side.
A spool sliding hole 12B having a diameter of 2A is formed, and the negative side of the spool sliding hole 12B in the axial direction becomes a screw hole 12D that opens to the outside via an annular step 12C, and the other side in the axial direction becomes an actuator side boat 12E. It becomes. Further, a hydraulic power source side boat 12F is formed in the valve casing 12 and is in constant communication with the annular groove 12A, and the boat 12F and the boat 12E are connected in the middle of the pipe line 4A.

Reference numeral 13 denotes a spool serving as a valve body inserted into the spool sliding hole 12B of the valve casing 12;
is formed into a cylindrical shape with a lid, and a flange 13A is provided on the lid side of the spool 13 that protrudes radially outward and regulates the stroke amount of the spool 13. Further, the cylindrical portion of the spool 13 has a radial sleeve hole 13B at an axially intermediate portion.
, 13B are bored, and each sleeve hole 13B is formed in the valve casing 1.
The two boats 12E and 12F are communicated with each other via an annular groove 12A, and are disconnected from each other. The spool 13 defines a control pressure chamber 14 between it and the boat 12E, and the pressure on the control pressure chamber 14 side is higher than the pressure on the pressure chamber 16 side than the set pressure of the pressure setting spring 12, which will be described later. It is designed to prevent this from happening.

Reference numeral 15 indicates a lid screwed into the screw hole 12D of the valve casing 12 from the outside, and the lid 15 has a cylindrical portion 15A and a lid portion 15.
A pressure chamber 16 is defined between the spool 13 and the lid side of the spool 13, and communicates with the hydraulic cylinder 2 via a branch pipe 8A of the pilot pipe 8. Reference numeral 17 denotes a pressure setting spring consisting of a coil spring located in the pressure chamber 16 and disposed between the lid part 15B of the lid body 15 and the spool 13, and the spring 17 always keeps the spool 13 in the valve-opening direction. The spool 13 is tilted at a predetermined set pressure to allow pressure oil from the hydraulic pump 1 to flow in the direction of arrow A toward the control pressure chamber 14 via the oil chamber 13B of the spool 13. The spool 13 closes when the pressure in the control pressure chamber 4 becomes higher than the pressure in the pressure chamber 6 by more than the set pressure of the spring 17, and the flange 13A closes the cylindrical portion 15A of the lid 15. When it comes into contact with the end face, the stroke amount in the valve closing direction is regulated.

Further, reference numeral 18 indicates an air bleed plug 7 screwed onto the center of the lid portion 15B of the lid body 15, and the air bleed plug 18 has an abbreviated air vent opening at the distal end surface and the proximal outer periphery. A vent hole 18A is formed, and the air vent hole 18A is connected to the plug 1.
8 is closed by the lid part 15B of the lid body 15, and the 0
° It is designed to be sealed by a nongrum 19.

The plug 18 is loosened from the lid 15 when venting the air in the pressure chamber 16, and by opening the air vent hole 18A to the outside, the air remaining in the pressure chamber 16 is removed from the oil liquid. is discharged to the outside of the valve casing 12 together with the parts.

In the conventional technology configured as described above, the hydraulic pump 1 is driven by a prime mover (not shown) 7, and the directional control valve 6 is switched from the neutral position (A) to the switching position (B) or (C). Pressure oil is supplied into the oil chambers 2B and 2A of the hydraulic cylinder 2, and the hydraulic cylinder 2 is operated. Further, 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 is 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 other actuators, the discharge amount of the hydraulic pump 1 is increased according to the load pressure of the other actuators, and a large amount of pressure oil is also supplied to the hydraulic cylinder 2. (A pressure compensation valve 11 is provided in the middle of the pipe line 4A to operate the hydraulic cylinder 2 independently from other actuators. In this case, the pressure compensation valve 11
The spool 13 is inserted into the spool sliding hole 1 of 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 (the load pressure of the hydraulic cylinder 2) by the set pressure of the bar 17. 2B and controls the flow rate of pressure oil flowing in the direction of arrow A between the boats 12F and 12E via the oil chamber 13B.

In addition, during shipping and maintenance of hydraulic excavators, etc.,
For example, when performing air bleeding inside the pressure chamber 16,
Loosen the air bleed plug 18 from the lid 15 and open the air bleed hole 1.
8A is opened to the outside, the air remaining in the pressure chamber 16 is jetted out together with a part of the oil, and after the air bleed operation is completed, the air bleed plug 18 is screwed onto the lid 15 again. The air vent hole 19 is sealed by the O-ring 19.

[Problems to be Solved by the Invention] By the way, in the above-mentioned prior art, the pressure chamber 16 of the pressure compensating valve 11 is oriented in the vertical direction, and the air bleed plug 18 is disposed above the pressure chamber 16. During the air bleeding operation, the air in the pressure chamber 16 can be discharged to the outside through the air bleeding hole 18A of the air bleeding plug 18.

However, since the pressure compensation valve 1] is arranged in a relatively limited space together with other hydraulic equipment, there are cases where the pressure chamber 16 cannot be oriented vertically, and the pressure chamber 16 is oriented as shown in FIG. (If the air release plug 18 is oriented in the left and right horizontal directions, the air release plug 18 cannot be placed above the pressure chamber 16, and the air in the pressure chamber 16 remains in the shaded area 20 in FIG. 5. Air cannot be reliably discharged to the outside.

Furthermore, as shown in FIG. If an enlarged diameter portion 21C is provided between the holes, it becomes possible to arrange the air bleed plug 18 above the pressure chamber 16 (as shown by the dotted line in FIG. 5).However, in this case, the lid When the body 21 is screwed into the screw hole 12D of the valve casing 12, the air bleed plug 18 also rotates together with the lid 21.
Unless a screw hole 21D for the air bleed plug 18 is formed in the enlarged diameter portion 21C of the lid body 21 in post-processing after screwing the
This air bleed plug 18 cannot be placed above the pressure chamber 16, which requires difficult machining work, resulting in a significant increase in cost.

In particular, in the pressure compensation valve 11, in order to set the differential pressure before and after the variable throttle 7 built in the directional control valve 6 to a predetermined pressure,
6 is provided with a pressure setting spring 17 made of a coil spring, and the spring 17 is disposed between the lid portion 15B (21B) of the lid body 15 (21) and the lid portion of the spool 13.
It becomes necessary to make the volume of the pressure chamber 6 relatively large, and as the amount of oil accommodated in the pressure chamber 16 increases, air tends to remain in the pressure chamber 16 (as shown in FIG. 5, the pressure chamber 16 There is a problem in that when the air bleed plug 18 is disposed horizontally, it becomes difficult to bleed the air.

The present invention has been made in view of the above-mentioned problems of the prior art.Even when the pressure chamber and the air bleed plug are arranged horizontally, the air in the pressure chamber can be discharged to the outside.
It is an object of the present invention to provide a valve device with an air bleed plug that can be hung and allows easy air bleed work.

[Means to solve the problem]

The feature of the configuration adopted by the present invention in order to solve the above problems is that one end side is pressed against the lid part of the lid body by a pressure setting spring in the pressure chamber, and the other end side extends in the axial direction within the spring. A rod-shaped spacer is provided, and the spacer includes a plurality of rod-shaped spacers extending obliquely from the outer periphery of the axially intermediate portion toward the center of the end surface on one end side and guiding the air in the pressure chamber toward the air bleed hole of the air bleed plug. The reason is that a guide groove is formed.

[Effect 1] With the above configuration, if the air bleed plug is loosened from the lid of the lid body and the air bleed hole is opened to the outside, the air inside the pressure chamber will flow radially from the outer circumference of the pressure chamber along each guide groove of the spacer. The air is discharged to the outside from the air vent hole while being guided obliquely inward, and air can be prevented from remaining on the outer peripheral side of the pressure chamber. Furthermore, the rod-shaped spacer can reduce the amount of oil in the pressure chamber, reducing the possibility that air will remain.

(Embodiment) Hereinafter, an embodiment of the present invention will be explained based on FIG. 3 instead of FIG. In the figure, reference numeral 31 denotes a lid that defines the pressure chamber 16 between it and the spool 13, and the lid 31 is similar to the lid 15 described in the prior art. is used in place of the cylindrical part 31
The area between A and the lid portion 31B is an enlarged diameter portion 31C.

An air bleed plug 18 is screwed into the center of the lid 31B of the lid 31 to bleed 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 part 31B of the lid body 31 by the pressure setting spring 17. As shown in FIGS. 2 and 3, the spacer 32 has one end side The head 32A is located in a large-diameter disk shape and has a pressure setting spring 17 disposed between it and the spacer 13.
and a detail 32B that is formed to have a smaller diameter than the head 32A and extends in the axial direction within the pressure setting spring 17, forming a bottle shape. The spacer 32 is positioned substantially coaxially within the lid body 31 by the pressure setting spring 17, and by filling most of the spacer within the lid body 31, the amount of oil accommodated in the pressure chamber 16 can be greatly reduced. It is designed to decrease. Further, the spacer 32 prevents the end surface of the shaft portion 32B from coming into contact with the spool 13 when the spool 13 slides in the valve closing direction and each sleeve hole 13B is blocked from the annular groove 12A of the valve casing 12. It is formed with a predetermined length dimension.

33.33. ... is on the head 32A of the spacer 32, etc."
It shows a slit-shaped guide groove formed by making four cuts in a - shape, and each of the inner grooves 33 is connected to the shaft portion 3.
It extends diagonally inward in the radial direction from the outer periphery of the head 2B toward the end surface of the head 32A, and joins at the center of the end surface of the head 32A. Then, the confluence portion 33 of each indoor groove 33
A is in constant communication with the air bleed hole 18A of the air bleed plug 18, and the air remaining on the outer peripheral side of the pressure chamber 16 is removed from the air bleed hole along the bottom of each guide groove 33 in the direction of arrow B in FIG. 1
It is designed to guide you towards 8A.

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

However, in this embodiment, the spacer 32 is positioned almost coaxially within the lid 31 by the pressure setting spring 17, and the spacer 32 fills most of the space within the pressure chamber 16, and the spacer 32 From the outer circumference of the head 32A and the shaft 32B (from the outer periphery of the part 32B to the head 32A
substantially cross-shaped guide grooves 33. .
Not only can the amount of air remaining in G be reduced, but also the air can be smoothly discharged to the outside through the guide grooves 33 during air bleeding work.

That is, if the air bleed plug 32 is loosened during the air bleed operation to open the air bleed hole 18A to the outside, the air remaining in the pressure chamber 16 will flow along the guide grooves 33 of the spacer 32 as shown by the arrows in FIG. The pressure oil in the pressure chamber 16 flows in the direction shown B toward the confluence section 33A, and while merging at the confluence section 33A, it comes to be ejected to the outside from the air vent hole 18A, thereby removing the air within the pressure chamber 16. It can be effectively discharged to the outside.

Therefore, according to this embodiment, even when the pressure chamber 16, the air bleed plug 18, etc. are arranged horizontally, the air in the pressure chamber 16 can be reliably discharged to the outside, and the air bleed operation can be easily performed. . Also, the amount of oil in the pressure chamber IG is determined by the spacer 32.
During the air bleeding operation, the pressure oil in the pressure chamber 16 flows into the air bleeding hole 8A from between the pressure setting spring 17 and the spacer 32 through each slit-shaped guide groove 33. Therefore, each guide groove 33 etc. can exert a throttling effect on the pressure oil, and various effects can be achieved, such as effectively preventing a large amount of pressure oil from being discharged to the outside together with the air during the air bleeding operation.

In the embodiment described above, the spacer 32 has four guide grooves 33, 33 . . . . However, instead of this, two, three or five or more guide grooves 33, 33, . . . are formed in the spacer 32,
Each of the indoor grooves 33 may extend radially from the center of the head 32A of the spacer 32.

Further, in the above embodiment, the pressure compensation valve provided for each actuator such as the hydraulic cylinder 2 in a hydraulic circuit employing a load sensing system, etc. has been described as an example, but the present invention is not limited to this. For example, it can be applied to various valve devices equipped with air vent plugs such as pressure control valves and flow rate control valves.

[Effects of the Invention] As detailed above, according to the present invention, a number rod-shaped spool is provided in the pressure chamber, and the spool has a plurality of guides for guiding air in the pressure chamber toward the air bleed hole of the air bleed plug. Since the grooves are formed, the spacer can reduce the amount of oil in the pressure chamber and the amount of residual air.In addition, during air bleeding work, the air in the pressure chamber can be channeled through each guide groove to bleed the air from the air bleed plug. It can be effectively discharged to the outside through the hole.
At this time, a large amount of pressure oil can be prevented from being discharged to the outside.
Air bleeding work can be performed easily.

[Brief explanation of the drawing]

1 to 3 show an embodiment of the present invention L7, FIG. 1 is a hydraulic circuit diagram including a pressure compensation valve, etc., 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 prior art, and FIG. 5 is a hydraulic circuit diagram similar to FIG. 4 showing another prior art. DESCRIPTION OF SYMBOLS 1... Hydraulic pump, 2... Hydraulic cylinder (actuator), 5... Tank, 6... Directional switching valve, 7...
...Variable throttle, 11...Pressure compensation valve (valve device), 12
...Valve casing, 12B...Spool sliding hole, 1
2D...Screw hole, 13...Spool (valve body), 16
...Pressure chamber, 17...Pressure setting spring, 18...Air bleed plug, 18A...Air bleed hole, 31...Lid body, 31A...Cylinder part, 31B...Lid part , 32...
Spacer, 32A...Head, 32B...Shaft, 33
...Guide groove.

Claims (1)

[Claims] a valve casing; a valve body that is slidably inserted into the valve casing and controls pressure oil supplied from a hydraulic source to the actuator; and a valve body that is screwed onto the valve casing and is connected to the actuator between the valve body and the valve body. a closed cylindrical lid defining a pressure chamber communicating with the pressure chamber; a pressure setting spring positioned within the pressure chamber and disposed between the lid of the lid and the valve body; In the valve device with an air bleed plug, the valve device has an air bleed hole for discharging the air remaining in the valve casing to the outside of the valve casing, and an air bleed plug screwed onto the lid of the lid body. A rod-shaped spacer is provided whose side is pressed against the lid part of the lid body by the spring and whose other end side extends in the axial direction inside the spring, and the spacer has a rod-shaped spacer that extends from the outer periphery of the axially intermediate part to the center of the end face of the one end side. 1. A valve device with an air bleed plug, characterized in that a plurality of guide grooves are formed that extend diagonally from the pressure chamber and guide air in the pressure chamber toward the air bleed hole of the air bleed plug.