JPH11132347A - Two stage relief valve - Google Patents

Abstract

PROBLEM TO BE SOLVED: To form a two stage relief valve using a valve body 1 of a standard type one stage relief valve as it is, and easily regulate pressure thereof by freely regulate the displacement of a piston formed integratedly with a rod having a support receiving surface of a spring for setting a valve opening pressure. SOLUTION: When pressure from a pressure passage P reaches setting pressure P1 , a pilot valve 1a is opened against a setting spring 8. Pressure oil flows from passage holes 24, 22, its oil pressure is released outside through an axial direction groove 210, thereby moving an opening/closing valve element 2b in a right direction by a pressure difference. As a result, oil pressure is returned into a tank through a low pressure passage T. In the case where high setting pressure is necessary, pilot pressure is made to act on a pilot passage P1, a piston 6 of bottomed sliding hole 37 is push-pressed, a rod 5 is moved in a left direction for a boost-up margin X capable of regulating by a shim 7, a compressed degree of the setting spring 8 is increased, and setting valve opening pressure of the pilot valve 1a is increased.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a two-stage relief valve.

[0002]

2. Description of the Related Art A relief valve is used in an upstream region of a hydraulic circuit, and is widely used as a safety valve for controlling a circuit pressure so as not to exceed a certain level. Normally, as shown in FIG. 1, such a relief valve is constituted by connecting a sub-body 2 having a pressure passage P and a low-pressure passage T to a valve body 1 having a built-in pilot valve 1a and a setting spring 8 for urging the pilot valve 1a to the closing side. A fixed valve member 2a having a passage acting on the open side of the pilot valve 1a is formed in the sub-body 2, and a low pressure passage T is urged by a spring 2c having the passage as a support surface. On-off valve body 2b that communicates with
have. Then, a screw 3 ′ having a pressure-receiving surface of the setting spring 8 is screwed from the rear end of the valve body 1, and the spring force of the setting spring 8 is adjusted according to the degree of screwing of the screw 3 ′ to set and change the relief pressure. It has become.

[0003] In such a relief valve, when pressure from the pressure passage P is introduced, the pressure is reduced to the passage hole 2.
When the pressure acts on the pilot valve 1a through the valves 4 and 22 and the pressure exceeds the force set on the spring, the pilot valve 1a opens and the hydraulic pressure acting on the pilot valve 1a is reduced.
Flows out of the valve through a passage groove 210 formed on the outer periphery of the valve, and the differential pressure causes the on-off valve body 2b to slide toward the fixing member 2a against the spring force, whereby the low-pressure passage T is formed. When opened, the oil pressure from the pressure passage P is returned to the tank. on the other hand,
In construction machines such as power shovels and so-called mini shovels in which crawlers are made of rubber, for example, the circuit pressure is set to 20.6 MPa at the time of front operation of a boom, a bucket, an arm, etc., and the driving force is increased during running. It becomes necessary to increase the pressure to 24.54 MPa. To respond to this demand, the pilot pressure is derived from the outside of the normal relief valve pressure set value, and the set pressure is changed (normally, the set pressure is increased).
There is a relief valve that can be used, and this is called a two-stage relief valve.

Conventionally, a structure as shown in FIG. 2 has been adopted as such a two-stage relief valve. That is, a valve body 1 'different from the valve body 1 in which the above-described sub body 2 is assembled is prepared, a hollow first screw D is screwed into the valve body 1', and the first nut N is tightened and fixed. 1 While inserting the piston F into the inner hole of the screw D so as to have the required pressure allowance x,
A second screw G having a pilot passage PI and a pilot passage hole pi is screwed into a hollow first screw D behind the screw, and tightened and fixed by a second nut H.

However, in such prior art, it is necessary to manufacture a valve body different from the one-stage relief valve, and two large screw types, a hollow first screw D and a second screw G, are required. , Because it requires two nuts, a first nut E and a second nut H,
It becomes large (especially the length dimension), and the material cost and precision processing cost increase. Further, since the piston F, the hollow first screw D, and the second screw G are independent parts, it takes time and effort to assemble, and there is a problem that the product becomes expensive.

[0006] The pressure adjustment operation is also very complicated and troublesome, and takes time. That is, in the prior art,
2, the first nut E and the second nut H are both loosened in this state. First, the degree of screwing of the second screw G with the hollow first screw D is determined. The spring length is adjusted so that the target set pressure, for example, 24.5 MPa is reached. When the pressure increase x becomes zero in this way, oil is caused to flow through the pressure passage P, and at this time, the degree of screwing of the first screw D into the valve body 1 'is adjusted, and the pressure increase P to be set is set.
_When the number becomes ₂ , the first nut E is tightened to fix the first screw D.

Next, the second screw G is loosened and moved to the right in FIG. 2, whereby the piston F is retracted to increase the length of the spring to create a step-up margin x, and the set pressure is reduced to the low set pressure P
_When it becomes ₁ , the second nut H is tightened to fix the second screw G. And a defined pressure to the pilot passage PI addition, it is confirmed that the internal pressure of the pressure passage P becomes the boost pressure P _2.

[0008]

SUMMARY OF THE INVENTION The present invention has been made in order to solve the above-mentioned problems, and it is an object of the present invention to provide a pressure control system which is easy to adjust the pressure, has a small number of parts, and has a simple structure. It is to provide a two-stage relief valve.

[0009]

In order to achieve the above object, the present invention provides a pilot valve, a valve body containing a setting spring for biasing the pilot valve, a pressure passage and a low pressure passage, and the pilot valve is provided inside. A sub-body having a fixed valve member provided with a passage acting on the opening side of the valve body, an opening / closing valve body which is urged by a spring having this as a supporting surface and which allows the low-pressure passage to communicate with the pressure passage when necessary, and an anti-pilot of the valve body A rod member having a screw member screwed into the female screw on the valve side, and a nut member screwed into a male screw on an intermediate outer periphery of the screw member, and a rod having a bearing surface of the setting spring at a tip end in an axial hole of the screw member. And a pilot passage coaxial with the shaft hole is connected to a sliding hole with a bottom, and a piston having a contact surface with the rod is pressurized therewith. It is the interpolated each other via a shim for integer.

Preferably, the screw member has a first male screw threaded to the female screw of the valve body on the outer periphery, a constricted portion having a smaller diameter than the first male screw, a non-threaded portion having a larger diameter than the constricted portion, and the first male screw. And a second external thread having a large diameter, and a backup ring having an outer diameter equal to or greater than that of the nut member between the nut member and the valve body. An O-ring holding washer having substantially the same inner diameter is assembled.

[0011] The backup ring has a concave portion on the end face for holding the outer diameter of the washer for holding the O-ring,
When the first male screw of the screw member passes through the inner hole of the O-ring holding washer in this state, the O-ring holding washer is deformed flat by pressure. A jig for press is used to hold the constricted portion by reducing the inner hole.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a two-stage relief valve according to the present invention will be described with reference to the accompanying drawings. 3 to 5 show a first embodiment of the present invention, which generally includes a valve body 1, a sub-valve body 2, a screw member 3 and a nut member 4 having a rod 5 and a piston 6 built therein. ing.

A female screw hole 10 is provided on the left end side of the valve body 1. A through hole 11, a female screw hole 12, and a seat hole 13 which is appropriately enlarged from the bottom of the female screw hole 10 are provided on an axis line to the right. Are sequentially formed. The sub-valve body 2 is provided with a plurality of low-pressure passage holes T on an outer periphery of an intermediate portion, and is provided with a male screw 21 on an outer circumference of a distal end region, and the male screw 21 is screwed into the female screw hole 10. It is connected to the valve body 1. In the sub-valve body, a fixed valve member 2a whose right end is in contact with the bottom of the hole of the valve body, an on-off valve body 2b and a spring 2c.
Is arranged.

The fixed valve member 2a has an O-ring whose outer periphery is oil-tight with the inner surface of the sub-valve body 2, and a passage hole 22 is formed on the axis, and the passage hole 22 is enlarged from the middle. In addition, a seat surface is formed at an opening portion facing the left end of the valve body 1. A pilot valve 1 a is disposed in the valve body 1, and a conical portion 14 at the tip of the pilot valve 1 a is inserted into the passage hole 22.

The opening / closing valve body 2b is formed in a cup shape having a concave portion 23 toward the fixed valve member 2a. A high pressure such as a pump discharge pressure acts between the right end face in the axial direction and the inner diameter face of the sub-body 2. A pressure passage P is formed, and the other end of a spring 2c, one end of which is supported by the fixed valve member 2a, is supported on the concave bottom portion on the opposite side, whereby the on-off valve body 2b normally operates at the low pressure. It is located so as to shield the passage T. A passage hole 24 communicating with the inside of the concave portion 23 is formed on the axis of the on-off valve body 2b.

The structure described above is the same as that of a conventional standard one-stage relief valve. The feature of the present invention is that the standard type 1
The two-stage relief valve is obtained by using the valve body 1 of the two-stage relief valve as it is. For this reason, the screw member 3 is a single assembly containing the rod 5 and the piston 6. As shown in FIG. 5, the screw member 3 includes, from the left end side, a first male screw portion 31, a constricted portion 32 having a smaller diameter than this, a screwless portion 33 having a relatively larger diameter than the constricted portion 32, A second male screw portion 34 having a diameter relatively larger than the non-thread portion 33 is sequentially coupled, and to the right of the second male screw portion 34, a diameter-enlarged portion having a polygonal outer surface. 35 are formed. No screw part 33
In general, it is preferable that the outer diameter is approximately equal to or larger than the ridge diameter of the first male screw portion 31.

The enlarged diameter portion 35 is formed with a bottomed sliding hole 37 of a required length following the cup-shaped pilot passage PI for guiding the pilot pressure, and is formed from the left end side of the screw member 3. On the axis, a shaft hole 39 is formed through a seated hole 38 having a predetermined depth from the left end, and the right end of the shaft hole 39 communicates with the bottomed sliding hole 37. The rod 5 is inserted into the shaft hole 39 so that the right end slightly projects into the bottomed sliding hole 37, and the left end is fitted in the seated hole 38 so as to be prevented from moving to the right. Head 50.

A spring 8 for setting a hydraulic pressure is interposed between the end face of the head 50 and the intermediate flange of the pilot valve 1a.
Is urged, and in the normal state, the conical portion 14
2 is in close contact with the right end seat surface. An oil chamber 16 is formed around the conical portion 14 of the pilot valve 1a. The oil chamber 16 is provided with a radial cutout provided in the right end face region of the fixed valve member 2a and an external thread 21 of the sub-valve body 2. The oil is communicated to the outside through the formed axial groove 210 so that the oil is released to the outside at a low pressure when the pilot valve 1a is opened.

The piston 6 is slidably inserted into the bottom slide hole 37, and the bottom end of the bottom slide hole 37 is provided at the bottom of the bottom slide hole 37 in order to adjust the pressure rise x. A required number of ring-shaped shims 7 are interposed between the ring-shaped shim 7 and the left end).

The nut member 4 serves to fix the length of insertion of the screw member 3 into the valve body 1 and is screwed to the second male screw portion 34 of the screw member 3 so as to be able to be loosened. On the left end side of the nut member 4, a backup ring 4 ′ which is fitted to the non-threaded portion 33 adjacent to the second male screw portion 34 of the screw member 3 is located.

The back coupling 4 ′ has an outer diameter larger than that of the valve body 1, and has a shallow recess 40 at an end surface facing the left end surface of the valve body 1 at a position substantially corresponding to the edge of the left end surface of the valve body 1. Are formed. A pressing washer 9 having an inner diameter substantially matching the outer diameter of the constricted portion 32 of the screw member 3 is fitted in the concave portion 40, and the pressing washer 9 is provided between the right end opening of the valve body 1 and the constricted portion 32. The fitted O-ring 15 is pressurized, thereby shutting off the hydraulic pressure leaking from the zone where the spring 8 is located to the outer periphery through the first external thread portion 31,
Oil tight seal. Thus, in the present invention, the backup ring 8 having the holding washer 9 is assembled to the screw member 3.

The backup ring 4 'utilizes a jig for press working. That is, as shown in FIG. 6 (a), the pressing washer 9 is
In order to reliably deform the O-ring 15, the holding washer 9 must be fitted in a constricted portion 32 having a smaller diameter than the first male screw portion 31. Therefore, the present invention provides a holding washer 9 whose inner diameter d is slightly larger than the ridge diameter of the first male screw portion 31 in the shallow recess 40 formed in the backup ring 4 ′ as a jig.
Is mounted so as to protrude into a trapezoidal shape as shown in FIG. 6B, and the outer diameter of the holding washer 9 is held by the surrounding wall of the concave portion 40. Then, in this state, the backup ring 4 ′ is arranged on the mold surface of the press die W, the screw member 3 with the nut member 4 attached thereto is inserted from the right mold hole w, and the tip portion penetrates the backup ring 4 ′. Let it. At this time, since the holding washer 9 is in the swelling state as shown in FIG. 6B, the first male screw portion 31 of the screw member 3 is attached to the holding washer 9.
Through the hole 90.

When the cylindrical punch Y is pressed against the backup ring 4 'in a state where the threadless portion 33 is fitted in the hole 40 of the backup ring 4', the washer 9 for holding is formed into a cylindrical shape. The sheet is strongly pressed by the punch Y and flattened. Since the outer diameter of the holding washer 9 is constrained by the surrounding wall of the concave portion 40, the inner diameter d is reduced solely by pressurization, and as a result, as shown in FIG. The backup ring 4 ′ is integrated with the screw member 3 so as to be almost in contact with the constricted portion 32. In this embodiment, the backup ring 4 'and the nut member 4 are separate members.
As shown in (e), the backup ring 4 'and the nut member 4
May be integrally formed in one member, which is also included in the present invention.

[0024]

Since the present invention is constructed as described above, a standard one-stage relief valve can be used as it is as the valve body 1 and the sub-valve body 2, and a washer, a nut member and a screw member are used. Remove it,
Screw member 3 containing rod 5 and piston 6
And the screw member 3 is also assembled with the backup ring 4 'and the nut member 4, so that it is sufficient to substantially integrate only one part into the valve body 1. Therefore, the assembling work is greatly simplified.

In addition, since the screw member 3 is single in dimension, the piston 6 can be freely inserted into and removed from the pilot passage PI in the rear end region of the screw member 3. The length of the conventional two-stage relief valve is shorter than that of the conventional two-stage relief valve, and the size can be reduced.

In order to adjust the pressure in the present invention, the nut member 4 is rotated and loosened in the assembled state as shown in FIG. The insertion length for 1 is changed.
When the insertion length of the screw member 3 is increased, the setting spring 8 interposed between the end face of the rod 5 and the intermediate flange of the pilot valve 1a is compressed, so that the set pressure is increased, and the insertion length of the screw member 3 is reduced. If the pressure is reduced, the compression of the setting spring 8 interposed between the end face of the rod 5 and the intermediate flange between the pilot valve 1a is weakened, so that the set pressure is reduced. Any case this set pressure P ₁ of the first stage is determined by the even. Then, the screw member 3 is tightened and fixed by rotating the nut member 4.

Next, the pilot passage PI at the right end of the screw member 3 is connected to a pilot hydraulic pressure supply system, and a specified pressure is applied through this. In this case, when the piston 6 is pressed, the rod 5 in contact with the piston 6 is pressed and moved leftward, and the compression of the setting spring 6 is increased. This causes a pressure increase, but if the pressure increase pressure at the pressure port on the side of the sub-valve body 2 does not reach the prescribed pressure increase P ₂ , the piston 8 is pulled out from the bottom slide hole 37 and the bottom slide slide hole 37 is pulled out. The number of the shims 7 arranged at the bottom of the hole 37 may be increased or decreased. Since this booster margin X is changed, the pilot pressure from the pilot passage PI of the right end addition of the piston 6 is again loaded, may be such that the pressure passage P in the boost pressure P ₂ defined.
Therefore, two-stage pressure adjustment can be performed very easily and accurately.

If the relief valve of the present invention adjusted in pressure as described above is incorporated in a hydraulic circuit, when the pressure from the pressure passage P is lower than the set pressure P ₁ as in the case of performing a front operation, the pressure is reduced. Even if it acts on the pilot valve 1a from the passage holes 24 and 22, the closed state is maintained by the force of the setting spring 8, so that the on-off valve body 2b does not move. However, the pressure from the pressure passage P becomes equal to the set pressure P ₁
Is reached, the setting spring 8 loses its pressure and opens. As a result, the pressure oil flows into the valve body 1 from the passage holes 24 and 22 and escapes to the outside through the axial groove 210.
Moves to the right, whereby the low pressure passage T communicates with the pressure passage P and is returned to the tank.

When a relatively high set pressure is required, such as when traveling, the pilot pressure is applied to the pilot passage PI from the pilot hydraulic pressure supply system.
By doing so, the piston 6 of the bottomed sliding hole 37 following the pilot passage PI is pressed, and the rod 5 moves to the left by the pressure allowance X adjusted by the shim 7. Therefore, compression degree of the spring 8 for setting to受支surface tip head 50 of the rod 5 is increased, set the valve opening pressure of the pilot valve 1a is changed to the boost pressure P _2. Therefore, the pilot valve 1a is opened when the pressure from the pressure passage P reaches the boosted pressure P _2, the low pressure passage T communicates with the pressure passage P, it is returned to the tank.

[0030]

According to the first aspect of the present invention, the valve body 1 having the pilot valve 1a and the setting spring 8 for urging the pilot valve 1a, the pressure passage P
And the low pressure passage T, and the pilot valve 1a therein.
Valve member 2a provided with a passage acting on the opening side of the valve and a low pressure passage T urged by a spring 2c having the passage as a supporting surface when necessary.
Sub-body 2 having an on-off valve body 2b for communicating with the pressure passage P, a screw member 3 screwed into the female screw 12 of the valve body 1 on the side opposite to the pilot valve, and a male screw 31 on an intermediate outer periphery of the screw member 3. A rod 5 having a nut member 4 and having a support surface for the setting spring 8 at a tip thereof in a shaft hole of the screw member 3;
And a pilot hole PI with a bottom is connected to the pilot passage PI which is coaxial with the shaft hole, and the piston 6 having a contact surface with the rod 5 is inserted therein through a shim 7 for adjusting the pressure. Since the nut member 4 has been inserted, the nut member 4 is loosened, and the screw member 3 is advanced or retracted to set a low pressure.
Pull out the piston 6 from the pilot passage PI and remove the shim 7
By adjusting the number of sheets, the high pressure can be set, so that the two-stage pressure adjustment can be performed very easily. Moreover, since only a single screw member and a nut member are added to the standard one-stage relief valve, it is possible to provide a compact and inexpensive two-stage relief valve with a small number of parts. The effect is obtained.

According to the second aspect, the screw member 3 is provided on the outer periphery with the first male screw 31 screwed into the female screw 12 of the valve body 1, a constricted portion 32 having a smaller diameter than the first male screw 31, and a non-constricted portion having a larger diameter than the constricted portion 32. Screw part 33 and first male screw 3
A second external thread having a diameter larger than 1; a backup ring 4 'having an outer diameter equal to or greater than that of the nut member 4 on an end surface of the nut member 4 facing the screw member; Since the O-ring holding washer 9 having an inner diameter substantially equal to the outer diameter of the constricted portion 32 is attached to the O-ring 15, the O-ring 15 is securely deformed so that the distance between the outer diameter of the screw member 3 and the inner diameter of the valve body 1 is reduced. Oil-tightness can be maintained, and the backup ring 4 ′ and the nut member 4 are assembled to the screw member 3, so that the rod 5 and the piston 6 are built in the screw member 3 and substantially It is possible to obtain an excellent effect that the number of necessary parts can be extremely reduced and the assembling can be facilitated.

[Brief description of the drawings]

FIG. 1 is a vertical side view of a conventional standard one-stage relief valve.

FIG. 2 is a vertical side view of a conventional two-stage relief valve.

FIG. 3 is a vertical sectional side view showing an example of a two-stage relief valve according to the present invention.

FIG. 4 is a side view of the same.

FIG. 5 is a partially enlarged view of FIG. 3;

FIG. 6A is a partially cutaway side view of a screw member according to the present invention, and FIG. 6B is a cross-sectional view showing a state in which a backup ring is used as a jig and a holding washer is attached. (C) is sectional drawing which shows the press state which attaches the washer for press to a screw member using the jig of (b). (E) is a partial view showing a press finished state.
(E) is sectional drawing which shows another example of the nut member and the backup ring in this invention.

[Description of Signs] 1 Valve body 2 Sub-valve body 3 Screw member 4 Nut member 4 'Backup ring 5 Rod 6 Piston 7 Shim 8 Setting spring 9 Holding washer 12 Female screw 31 First male screw 32 Constricted part 33 No screw part 34 2nd male screw 37 Bottom sliding hole

Claims (2)

[Claims] 1. A fixed valve member having a pilot valve, a valve body containing a setting spring for biasing the pilot valve, a pressure passage and a low pressure passage, and having a passage formed therein for acting on the open side of the pilot valve. A sub-body having an opening / closing valve body which is urged by a spring having this as a supporting surface and communicates the low-pressure passage with the pressure passage when necessary, a screw member screwed into a female screw of the valve body on the side opposite to the pilot valve; A nut member screwed into a male screw on the middle outer periphery of the screw member is inserted into a shaft hole of the screw member, and a rod having a bearing surface for the setting spring is inserted into a tip of the screw member, and a pilot passage coaxial with the shaft hole is provided. A two-stage sliding hole connected to a bottomed sliding hole, into which a piston having a contact surface with the rod is inserted via a shim for adjusting a pressure rise. Leaf valve. 2. A first male screw having a screw member screwed to an internal thread of a valve body on an outer periphery, a constricted portion having a smaller diameter than the first male screw, and a non-threaded portion having a larger diameter than the constricted portion.
A second male screw having a diameter larger than the male screw, and an end face side of the nut member facing the screw member,
2. The O-ring holding washer according to claim 1, further comprising a backup ring having an outer diameter equal to or greater than that of the nut member, and an O-ring holding washer having an inner diameter substantially equal to the outer diameter of the constricted portion. Step relief valve.