KR20080097029A - Two stage relief valve - Google Patents

Abstract

A two stage pressure control valve is provided to change the set pressure easily by offsetting pressure from the drained operation fluid. A sleeve(2) has an operation fluid inflowing route and a drain pathway. A poppet(6) built-in in the sleeve opens and closes the operation fluid influx route. A first elastic member supports the poppet against the poppet opening direction. If a high pressure over the set value is generated in the pressure of the sleeve, the pilot poppet(12) drains the operation fluid to the hydraulic tank. An auxiliary piston(7) contacts the pilot poppet slid in the inside of the poppet by the initial pressure of the operation fluid from the hydraulic pump. A second elastic member(11) supports the auxiliary piston. A third elastic member(14) supports the pilot poppet against the pilot opening direction.

Description

Two stage relief valve

1 is a cross-sectional view of a two-stage pressure control valve according to the prior art,

2 is a state diagram used in the control valve shown in FIG.

3 is a cross-sectional view of a two-stage pressure control valve according to an embodiment of the present invention;

4 is a state diagram used in the control valve shown in FIG.

5 is an essential part excerpt of the pressure control valve shown in FIG. 3.

* Explanation of symbols used in the main part of the drawing

One; plug

2; Sleeve

6; Poppet

7; Auxiliary piston

10; First elastic member

11; Second elastic member

12; Pilot poppet

14; Third elastic member

17; piston

19; core

21,23; nut

22; Adjustable plug

The present invention provides a two-stage pressure control valve that can be easily adjusted from the standard pressure (0-40k) to a high pressure when the set pressure of the two-stage relief valve is adjusted by input of pilot pressure from the outside. It is about.

More specifically, when an overload exceeding the set pressure occurs in the hydraulic circuit, the two-stage relief valve is set by canceling the back pressure generated by the hydraulic oil which is partially or entirely drained into the hydraulic tank. The present invention relates to a two-stage pressure control valve that allows the pressure to be easily changed from standard pressure conditions to high pressure.

As shown in Fig. 1 and Fig. 2, the two-stage pressure control valve according to the prior art includes a sleeve (2) having a drain passage (b), a tank passage (j) and a hydraulic oil inlet passage (r),

A poppet (6) which is installed in the sleeve (2) to open and close the hydraulic oil inflow passage (r),

A first elastic member 10 (compression coil spring) for elastically supporting the poppet 6 in a direction in which the poppet 6 opens;

In the case where a high pressure of a set value or more is generated in the pressure chamber c of the sleeve 2, the pilot poppet 12 is opened to drain the hydraulic oil to the hydraulic tank m through the drain passage b;

A shim 19 in contact with the sleeve 2 and the pilot poppet 12 seated;

An auxiliary piston 7 sliding in the poppet 6 by the initial pressure of the hydraulic oil discharged from the hydraulic pump h and contacting the pilot poppet 12;

A second elastic member 11 (compression coil spring) for elastically supporting the auxiliary piston 7;

A third elastic member 14 (compression coil spring) that elastically supports the pilot poppet 12 against the direction in which the pilot poppet 12 is opened,

A piston 17 that elastically supports the third elastic member 14 and slides upon input of pilot pressure from the pilot pump k to pressurize the elastic member 14, thereby increasing the set pressure of the hydraulic circuit;

An adjustment plug 22 which is screwed to the guide 20 and presses one end of the piston 17 to maintain a set pressure;

And nuts 21 and 23 to prevent changes after setting pressure.

In the drawings, reference numeral 1 is a plug connecting the sleeve 2 and the guide 20.

A) The case where an overload exceeding the set pressure occurs in the hydraulic circuit (in the case where the pilot pressure is not supplied from the pilot pump k to the piston 17) will be described.

As shown in FIG. 2, the auxiliary piston 7 overcomes the elastic force of the second elastic member 11 by the hydraulic fluid flowing in from the hydraulic pump h through the inflow passage r. Is moved. The high pressure hydraulic fluid flows through the passage f inside the auxiliary piston 7 and flows into the pressure chamber c.

At this time, since d1 (inner diameter of the inflow passage r) < d2 (outer diameter of the poppet 6), the poppet 6 remains in close contact with the seat surface of the sleeve 2 (state shown in Fig. 1). .

When the pressure of the hydraulic oil flowing into the pressure chamber c reaches the elastic force of the third elastic member 14, the pilot poppet 12 is opened (the third elastic member 14 is compressed). The hydraulic oil of the pressure chamber c is drained to the hydraulic tank m via the through hole n of the shim 19 and the drain passage b of the sleeve 2.

At the same time, since the hydraulic oil pressure in the pressure chamber c drops instantaneously with the opening of the pilot poppet 12, the poppet 6 is moved in the right direction in the drawing. That is, since (discharge pressure x d1 cross-sectional area of the hydraulic pump h)> (pressure x d2 cross-sectional area of the pressure chamber c), the poppet 6 is opened so that the hydraulic oil from the hydraulic pump h passes through the tank passage j. It passes through and returns to the hydraulic tank (m).

B) The case where the set pressure of the hydraulic circuit is adjusted to high pressure (in the case where the pilot pressure is supplied from the pilot pump k to the piston 17) will be described.

As shown in FIG. 2, when the pilot pressure from the pilot pump k is introduced through the passage g formed in the piston 17, the piston 17 is moved in the left direction in the drawing. As the piston 17 moves, the third elastic member 14 is compressed to increase the set pressure of the pilot poppet 12 to increase the set pressure of the relief valve.

In this way, when the pilot pressure is input and the standard set pressure of the hydraulic circuit is changed to high pressure, back pressure is formed in the chamber a by the working oil returned from the pressure chamber c to the hydraulic tank m. The back pressure of the chamber a is transmitted to the piston 17.

On the other hand, when the set pressure of the relief valve is increased by using the pilot pressure, the following formula must be satisfied to smoothly boost the relief valve.

(Pilot pressure × large diameter D1 of piston 17)> (back pressure × (large diameter D1 of piston 17 + (set pressure of relief valve x small diameter D2 of pilot poppet 12) At this time, the set pressure of the relief valve means the pressure before the boost.

Alternatively, when the set pressure of the relief valve is increased by using the pilot pressure, it may be expressed as follows.

(Pilot pressure)> (Back pressure + (Set pressure / area ratio of relief valve), where area ratio means (small diameter (D2) of pilot poppet (12)) / (large diameter (D1) of piston (17)) do.

At this time, as the flow rate flowing into the pressure chamber (c) increases, the back pressure generated in the chamber (a) increases. As the back pressure increases, the pilot pressure input to the piston 17 must be increased to increase the set pressure of the relief valve.

Therefore, when the flow rate flowing into the pressure chamber c is large, a change in the set pressure of the relief valve is difficult under the input of the standard pressure (0-40k), so that a separate device capable of canceling the back pressure is required. In addition, there is a problem that the pilot pressure should be increased as the set pressure of the relief valve is increased.

According to an embodiment of the present invention, when the set pressure of the two-stage relief valve is variably adjusted, an overload exceeding the set pressure is generated in the hydraulic circuit so that the relief valve is not affected by the back pressure generated by the hydraulic oil drained. It is associated with a two-stage pressure control valve that makes it easy to change the set pressure.

Two-stage pressure control valve according to an embodiment of the present invention, the hydraulic fluid inlet passage and the drain passage is formed,

A poppet built into the sleeve to open and close the hydraulic oil inlet passage,

A first elastic member elastically supporting the poppet in a direction in which the poppet opens;

A pilot poppet which is opened when a high pressure of a set value is generated in the pressure chamber of the sleeve and drains the hydraulic fluid to the hydraulic tank through the drain passage;

Auxiliary piston sliding in the poppet by the initial pressure of the hydraulic fluid discharged from the hydraulic pump and in contact with the pilot poppet,

A second elastic member elastically supporting the auxiliary piston,

A third elastic member elastically supporting the pilot poppet against a direction in which the pilot poppet opens;

The set pressure of the relief valve is varied by pressing the third elastic member according to the input of the pilot pressure from the pilot pump, and the back pressure generated by the hydraulic oil drained to the hydraulic tank due to an overload generated exceeding the pressure set in the hydraulic circuit is generated. A piston through which the passage is formed so as to cancel out;

It includes an adjusting plug that pressurizes the piston to maintain the set pressure.

According to a preferred embodiment, the front signal pressure surface and the rear signal pressure surface of the piston acting the back pressure by the passage formed in the above-described piston is formed to have the same cross-sectional area.

Hereinafter, preferred embodiments of the present invention will be described with reference to the accompanying drawings, which are intended to describe in detail enough to enable those skilled in the art to easily practice the invention, and therefore It does not mean that the technical spirit and scope of the present invention is limited.

3 and 5, the two-stage pressure control valve according to an embodiment of the present invention, the inflow passage (r), the tank passage (j) and the drain passage in which the hydraulic oil flows from the hydraulic pump (h) ( b) formed sleeve (2),

A poppet (6) which is installed in the sleeve (2) to open and close the hydraulic oil inflow passage (r),

A first elastic member 10 elastically supporting the poppet 6 in a direction in which the poppet 6 opens;

In the case where a high pressure of a set value or more is generated in the pressure chamber c of the sleeve 2, the pilot poppet 12 is opened to drain the hydraulic oil to the hydraulic tank m through the drain passage b;

An auxiliary piston 7 sliding in the poppet 6 by the initial pressure of the hydraulic oil discharged from the hydraulic pump h and contacting the pilot poppet 12;

A shim 19 in contact with the sleeve 2 and the pilot poppet 12 seated;

A second elastic member 11 elastically supporting the auxiliary piston 7;

A third elastic member 14 elastically supporting the pilot poppet 12 in a direction in which the pilot poppet 12 is opened;

Pressing the third elastic member 14 according to the input of the pilot pressure from the pilot pump k to vary the set pressure of the relief valve, and an overload exceeding the pressure set in the hydraulic circuit is generated to the hydraulic tank m. A piston 17 having a passage s formed therein so as to cancel back pressure generated by the hydraulic oil being drained;

An adjusting plug 22 which is screwed to the guide 20 and pressurizes the piston 17 to maintain a set pressure;

Screwed to the adjustment plug 22 and the guide 20, and includes a nut (21, 23) to prevent the change after setting the set pressure of the relief valve.

The front signal pressure surface 17a and the rear signal pressure surface 17b of the piston 17, where the back pressure acts by the passage s formed in the above-described piston 17, are formed to have the same cross-sectional area (D3 = D4). (Shown in Figure 5).

At this time, the configuration except for the piston 17 through which the passage (s) is formed so as to cancel the back pressure generated by the hydraulic oil drained into the hydraulic tank (m), they are applied substantially the same as shown in Figure 1 Detailed descriptions thereof will be omitted, and the same reference numerals will be used throughout the drawings.

Hereinafter, an example of use of a two-stage pressure control valve according to an embodiment of the present invention will be described with reference to the accompanying drawings.

A) The case where an overload exceeding the set pressure occurs in the hydraulic circuit (in the case where the pilot pressure is not supplied from the pilot pump k to the piston 17) will be described.

As shown in FIG. 4, the auxiliary piston 7 overcomes the elastic force of the second elastic member 11 by the hydraulic oil introduced from the hydraulic pump h through the inflow passage r, and moves to the right in the drawing. do. The high pressure hydraulic fluid flows through the passage f inside the auxiliary piston 7 and flows into the pressure chamber c.

At this time, since d1 (inner diameter of the inflow passage r) < d2 (outer diameter of the poppet 6), the poppet 6 remains in close contact with the seat surface of the sleeve 2 (state shown in Fig. 3). ).

When the pressure of the hydraulic oil flowing into the pressure chamber c reaches the elastic force of the third elastic member 14, the pilot poppet 12 is opened. The hydraulic oil of the pressure chamber c is drained to the hydraulic tank m via the through hole n of the shim 19 and the drain passage b of the sleeve 2.

At the same time, since the hydraulic oil pressure in the pressure chamber c drops instantaneously with the opening of the pilot poppet 12, the poppet 6 is moved in the right direction in the drawing. That is, since (discharge pressure x d1 cross-sectional area of the hydraulic pump h)> (pressure x d2 cross-sectional area of the pressure chamber c), the poppet 6 is opened so that the hydraulic oil from the hydraulic pump h flows in the inflow passage r. And passes directly through the tank passage (j) to the hydraulic tank (m).

B) The case where the set pressure of the hydraulic circuit is adjusted to high pressure (in the case where the pilot pressure is supplied from the pilot pump k to the piston 17) will be described.

As shown in Fig. 4, when the pilot pressure from the pilot pump k is introduced through the passage g formed in the piston 17, the piston 17 is moved in the left direction in the drawing. As the piston 17 moves, the third elastic member 14 is compressed to increase the set pressure of the pilot poppet 12 to increase the set pressure of the relief valve.

The hydraulic oil from the above-mentioned hydraulic pump h is supplied to the pressure chamber c via the inflow passage r-the passage f of the auxiliary piston 7. A part of the hydraulic oil which is moved from the pressure chamber c to the chamber u by opening the poppet 6 is drained into the hydraulic tank m through the drain passage b of the sleeve 2.

On the other hand, the remainder of the hydraulic fluid moved to the chamber (u) is supplied to the chamber (t) along the passage (s) formed through the interior of the piston (17). At this time, as the front signal pressure surface (17a) and the rear signal pressure surface (17b) of the piston 17 is formed to have the same cross-sectional area (D3 = D4) (shown in Figure 5), back pressure to the chamber (t, u) Even when they are formed, they are canceled with each other by the passage s.

As described above, when the pilot pressure is input from the pilot pump k to change the standard set pressure of the hydraulic circuit to high pressure, the following equation is used to cancel the back pressure formed by the hydraulic oil returned to the hydraulic tank m. The pressure relief of the relief valve should be smoothly achieved.

(Pilot pressure x large diameter D1 of piston 17)> (set pressure of relief valve x small diameter D2 of pilot poppet 12). If this is satisfied, the set pressure of the relief valve can be smoothly changed to high pressure.

At this time, the set pressure of the relief valve means the pressure before the boost.

Alternatively, when the set pressure of the relief valve is increased by using the pilot pressure, the back pressure may be canceled as follows.

(Pilot pressure)> (Relief valve set pressure / area ratio). In this case, the area ratio means (small diameter D2 of the pilot poppet 12) / (large diameter D1 of the piston 17).

Therefore, even when the back pressure is formed in the chambers u and t, the pilot pressure from the pilot pump k is supplied to the piston 17 so that the set pressure of the relief valve is increased to high pressure, so that the back pressure is not interrupted. .

As described above, the two-stage pressure control valve according to the embodiment of the present invention has the following advantages.

When the set pressure of the two-stage relief valve is variably adjusted, the set pressure of the relief valve can be easily changed as the overload exceeding the set pressure in the hydraulic circuit is canceled and the back pressure generated by the drained hydraulic oil is canceled. Can have the reliability of equipment

Claims (2)

A sleeve having a hydraulic oil inflow passage and a drain passage formed therein; A poppet built into the sleeve to open and close the hydraulic oil inflow passage; A first elastic member elastically supporting the poppet in a direction in which the poppet is opened; A pilot poppet which is opened to drain hydraulic fluid to the hydraulic tank through the drain passage when a high pressure of a predetermined value or more is generated in the pressure chamber of the sleeve; An auxiliary piston sliding in the poppet by the initial pressure of the hydraulic oil discharged from the hydraulic pump and contacting the pilot poppet; A second elastic member elastically supporting the auxiliary piston; A third elastic member elastically supporting the pilot poppet in a direction in which the pilot poppet is opened; The third elastic member is pressurized according to the input of the pilot pressure from the pilot pump to change the set pressure of the relief valve, and the back pressure generated by the hydraulic oil drained to the hydraulic tank by generating an overload exceeding the pressure set in the hydraulic circuit. A piston through which the passage is formed so as to cancel the; And And a regulating plug for pressurizing the piston to maintain a set pressure. The two-stage pressure control valve according to claim 1, wherein the front signal pressure surface and the rear signal pressure surface of the piston, through which the back pressure acts by the passage formed in the piston, have the same cross-sectional area.

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