KR100205567B1 - Variable priority apparatus - Google Patents

Abstract

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a variable priority device, and more particularly to a logic valve installed in a pump passage of a low pressure side control valve in a hydraulic line where a plurality of work devices are driven by a single pump to block a pump passage in proportion to a predetermined signal. In the variable priority device provided, a sequence valve for recognizing a pilot pressure capable of operating the high pressure side work device and receiving an operating hydraulic pressure pumped from a pump to supply an output side signal for controlling the area of the orifice of the logic valve It relates to a variable priority device characterized in that provided.

Description

Variable priority

The present invention relates to a variable priority device, in particular a logic valve is installed in the pump passage of the low pressure side control valve in a hydraulic line of a heavy equipment such as an excavator in which a plurality of working devices are driven by one pump, and in proportion to a predetermined signal. It is equipped with a sequence valve which shuts off the pump passage and supplies a predetermined signal to the logic valve, recognizes the pilot pressure at which the high pressure side work device can be operated, and feeds back the hydraulic pressure pumped from the pump to the orifice of the logic valve. The present invention relates to a variable priority device in which the low pressure side work device and the high pressure work device are operated at the same time by controlling the area to minimize the time delay during which the high pressure work device is operated after the low pressure work device is operated.

In general, the 'priority' applied to heavy equipment is to control the high-load actuator to receive a relatively higher flow rate than the low-load actuator when at least two or more actuators are combined by oil discharged from a single pump. will be. For example, in the case of an excavator, the turning priority is applied to the arm, and the boolean priority is applied to the bucket. The reason for applying this priority is that the flow rate required for turning is larger than the flow rate required for the arm operation. Since the required flow rate is larger than the required flow rate at the time of operation, the flow rate is differentially supplied so that the high load work device is operated in proportion to the moving speed of the low load work device to smoothly operate the equipment as a whole.

When such a priority device is applied to the boom of the excavator and the hydraulic line driving the bucket, a fixed orifice is used in the hydraulic supply line of the low load bucket, but the pressure loss when the bucket is operated alone when the fixed orifice is used. This occurred and eventually, there was a problem that the working pressure discharged from the pump could not be sufficiently used in the working device.

Among various measures to improve this, a sequence variable control device is developed in which a low-load supply flow rate is automatically selected according to the load pressure of a high load work device and a low load work device to improve work efficiency and operation sensation. .

That is, the variable priority device of such an excavator, as shown in Figure 1, to drive a plurality of actuators boom cylinder (3) and bucket cylinder (6) through a flow path (1A) in one pump (1) Boom drive control valves (hereinafter abbreviated as 'BOOM') (2) and bucket drive control valves (hereinafter abbreviated as 'BKT') on parallel flow paths 2A and 5A branching the flow path 1A, respectively. (5) and a piston (7), a load check (9), and a piston formed above the piston (7) so as to be movable up and down in the hydraulic oil supply passage (9A) of the BKT (5). An opening area of the orifice 10 formed between the lower portion of the rod 9 9 and the supply passage 9A is provided with a logic valve LV having a pressure chamber 8 formed therein and a pressure change of the piston pressure chamber 8. In order to supply the hydraulic pressure to the piston pressure chamber (8), a sequence valve (4) formed with an output side flow passage (12) is provided with a hydraulic line connected to the piston pressure chamber (8). It was.

As shown in Fig. 2, the sequence valve 4 includes an output side passage 12 communicating with the piston pressure chamber 8, an input side passage 11 and a return passage 18 branching off the passage 1A. The sleeve 14 is inserted into the housing 40 in which the output side port 12A, the pump port 11A, and the drain port 18A are formed, respectively, and a flow path for supplying a pilot pressure Pi to the BOOM 2. The pilot piston 17, which is moved by the pilot pressure of the pilot flow passage 23 branching inwards, is inserted to be movable left and right, and the other end of the spool 13 sliding with one end of the pilot piston 17 is return spring ( 15 is inserted into the sleeve 14 to be supported by the spool 13, the inner passage 30 is formed in the spool 13 to communicate the pump port 11A and the output side port 12A as the spool 13 moves, An end portion of the inner diameter chamber 32 formed in communication with the inner passage 30 at the center of the spool 13 is interlocked with the protrusion 16 protruding from the other end of the housing 40.

In this configured state, when performing the combined operation of the boom UP and bucket IN during the excavation, the pilot pressure Pi for driving the BOOM (2) is the pilot piston of the sequence valve (4) through the flow path (23) As the pilot piston 17 is moved to the right in the drawing of FIG. 2, the spool 13 is pushed to the right to overcome the elastic force of the return spring 15 and actuated by the inner passage 30. The port 11A communicates with the output side port 12A. Accordingly, the working oil is supplied to the output side port 12A, the pressure in the piston pressure chamber 8 rises, and the piston 7 and the rod 9 9 move downward, so that the opening area of the orifice 10 becomes small, and thus the hydraulic pump ( Through 1), the working flow rate flowing into the BKT 5 decreases, and eventually, the operating flow rate for driving the boom increases.

6 represents the pilot pressure Pi supplied to the sequence valve 4, and the Y axis represents the pressure acting on the output side port 12A of the sequence valve 4, i.e., the flow of the piston pressure chamber 8; Indicates pressure. As shown in the drawing, when the initial pilot pressure Pi rises, the inner passage 30 communicating with the output side port 12A communicates with the pump port 11A as the spool 13 is turned to the right, and thus the output side passage 12 Will increase linearly. In addition, since the inner passage 30 and the inner diameter chamber 32 communicate with each other, an operating pressure of the pump port 11A is formed in the inner diameter chamber 32. In this state, the equilibrium of the force in the sequence valve 4 is A ₁ for the cross section of the pilot piston 17, A ₂ for the cross section of the inner diameter chamber 32, Pi for the pilot pressure, and pressure for the inner diameter 32. When the elastic force of P ₁ and the return spring 15 is Fs ₁ ,

PiA ₁ = P ₁ A ₂ + Fs ₁

In other words, in equation 1, the left side of the equal sign represents a force for pushing the spool 13 to the right, and the right side of the equal sign represents a force pushing the spool 13 to the left. Since Fs ₁ is a constant and increasing Pi with P ₁ constant, the spool 13 is moved to the right proportionally, and the open area of the pump port 11A increases linearly, resulting in an output side port 12A. The operating pressure of) is the same as the diagram A of FIG. 6, wherein Pi ₁ of the diagram A is the pilot pressure at which the bucket is initially operated, and Pi ₂ is the pilot pressure at which the boom is initially operated.

However, when the boom and the bucket operate in combination, the boom up operation is not performed due to the difference in the operating pressure from the operating pressure Pi ₂ , in which the boom is relatively larger than the operating pressure Pi ₁ . The pilot pressure section Pi ₁ to Pi ₂ , in which only the bucket IN operation is performed, was eventually operated by the pilot pressure in this section. Therefore, the work function intended by the operator is not performed correctly, and at the same time, there is a problem in that the driving feeling becomes poor and the work efficiency is lowered.

It is an object of the present invention to recognize a pilot pressure at a set pressure at which a high pressure side work device can be operated to a high pressure side control valve, and supply a control pressure to the logic valve so that the low pressure side work device is not driven up to this set pressure. It is to provide a variable priority device.

Another object of the present invention is to control the area of the orifice of the logic valve by feeding back the hydraulic pressure pumped from the pump, thereby minimizing the time delay in which the high pressure side work device is operated after the low pressure side work device is operated. It is to provide a variable priority device that allows the working device to operate at the same time to improve the working efficiency of the equipment.

1 is a mechanism diagram showing a conventional variable priority device;

2 is an enlarged view of a sequence valve in FIG.

3 is a mechanism diagram schematically showing a variable priority device according to an embodiment of the present invention;

4 is an enlarged view of a sequence valve in FIG. 3;

Figure 5 (a) (b) (c) and (d) is an operating state diagram of the sequence valve of Figure 4, and

6 is a graph showing a change in the hydraulic pressure on the output side of the sequence valve as the pilot pressure acting on the sequence valve increases.

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

LV: Logic Valve 1: Hydraulic Pump

1A: Euro

2: Control valve for boom drive (= high pressure control valve)

3: Boom cylinder (low pressure side work device) 4: Sequence valve

5: Bucket drive control valve (= low pressure side control valve)

6: Bucket cylinder (low pressure side work device) 7: piston

8: Piston Pressure Chamber 9: Load Check

10: Orifice 11: Input side flow path

11 A: Pump port 12: Output side flow path

12 A: Output side port 13: Spool

14: sleeve 15: return spring

16: protrusion 17: pilot piston

18: Return flow path 18A: Drain port

19: Pilot Piston 20: Guide

21: elastic member 22: piston

23: pilot euro 24: through

25: sequence valve 26: hollow part

27: load 28: plug

30: internal passage 32: inner diameter room

40: housing

An object of the present invention described above is a variable having a logic valve installed in a pump passage of a low pressure side control valve in a hydraulic line in which a plurality of working devices are driven by a single pump and blocking the pump passage in proportion to a predetermined signal. First, in the apparatus, a sequence for recognizing the pilot pressure at which the high pressure side work device can be operated by the high pressure side control valve, and supplying an output side signal for controlling the area of the orifice of the logic valve by receiving the hydraulic pressure pumped from the pump. It is achieved by providing a variable priority device characterized in that it is provided with a valve.

According to a preferred feature 1 of the present invention, the sequence valve, the pump passage to which the hydraulic oil discharged from the pump is supplied, the output side passage connected to the logic valve, a plurality of drain passages are formed, the housing having a through hole in the center and A pilot piston inserted into one side of the through hole in a perturbable manner, the pilot piston communicating with a pilot flow path of the high pressure side control valve so that one side functions as a pilot pressure for driving the high pressure side control valve, and a hollow portion formed inside the pilot piston; A piston inserted in one end of the hollow portion in a perturbable manner, a rod fixed to the other side of the piston and extending in the other side, a guide inserted in the other end of the hollow portion in a perturbable manner, the other end protruding outward from the piston And means for recognizing a pilot pressure at which the high pressure side work device is driven inside the hollow part, and at the other side of the through hole. The pump port is fixedly inserted, and the pump port, which is in communication with the pump passage, the output side passage and the drain passage, the sleeve having the output side port and the drain port are formed, and are perturbably inserted into the sleeve. The other end is formed in one end of the spool elastically supported by the return spring, and the pump port is in communication with the drain port in proportion to the movement of the spool from the initial state of communicating the pump port and the drain port of the sleeve Internal passages for blocking the flow rate and increasing the communication area with the output side port, a plug fixed to the other end of the through hole of the housing to support the other end of the return spring, and feedback for switching the spool to an initial state against the pilot pressure. It is provided with a means.

According to a preferred feature 2 of the present invention, the recognizing means is provided between the piston and the guide to maintain the stroke ending state of the piston to one side, by elastically biasing the guide to maintain the stroke ending state to the other side of the It is configured to include an elastic member for maintaining a predetermined interval between the other end of the rod and one end of the guide.

In the preferred feature 3 of the present invention, the elastic force of the elastic member, the sequence for driving the logic valve to operate the low pressure side working device and the high pressure side working device at the same time by limiting the opening area of the pump passage on the low pressure side The sequence pilot pressure when pressure is created at the output port is set equal to the force acting on the cross-sectional area of the pilot piston.

In a preferred feature 4 of the present invention, the feedback means is formed inside the spool, and includes an inner diameter chamber communicating with the inner passage, and one end of the inner diameter chamber protruding from the plug. do.

In a preferred feature 5 of the present invention, as the pilot pressure acting on the sequence valve is increased, the sum of the elastic force of the elastic member of the pilot piston, the pressure acting on the inner diameter chamber of the spool and the elastic force of the return spring is increased. A first step of achieving an equilibrium state, a pilot step acting on the piston of the pilot piston, a second step of forming an equilibrium state with a sum of the pressure acting on the inner diameter chamber of the spool and the elastic force of the return spring, and the pilot When the pilot pressure acting on the piston of the piston overcomes the sum of the pressure acting on the inner diameter chamber of the spool and the elastic force of the return spring, a third step of obtaining an equilibrium state is sequentially performed.

Hereinafter, preferred embodiments of the present invention will be described based on the accompanying drawings.

FIG. 3 is a schematic view showing a variable priority device according to an embodiment of the present invention, and FIG. 4 is an enlarged view of a sequence valve in FIG. 3, and FIGS. 5 (a) (b) (c) and (d). ) Is an operation state diagram of the sequence valve, Figure 6 is a graph showing a change in the hydraulic pressure of the output side of the sequence valve as the pilot pressure acting on the sequence valve is increased.

As shown in FIG. 3, the variable priority device according to the present embodiment includes a low pressure side work device 6 and a hydraulic pressure line in which a plurality of work devices 3 and 6 are driven by one hydraulic pump 1. An excavator having a logic valve (LV), which is divided into a high pressure side working device (3) and installed in the pump passage (9A) of the low pressure side control valve (6), shuts off the pump passage (9A) in proportion to a predetermined signal. Applied to heavy equipment such as.

Low pressure side and high pressure side control valves 5 and 2 for switching the hydraulic oil supplied to these actuators by the low pressure side actuator 6, the high pressure side actuator 3, and the pilot signal Pi driven from the hydraulic pump 1; For the logic valve LV installed in the low pressure side pump passage 9A and components substantially the same as those of the prior art described in FIGS. 1 and 2, the same reference numerals are used in the present embodiment, and detailed description thereof will be omitted. Reveal.

The variable priority device according to the present embodiment recognizes the pilot pressure (Pi _{1 in} the diagram B of FIG. 6) in which the high pressure side work device 3 can be operated by the high pressure side control valve 2, and from the pump 1 It is configured to include a sequence valve 25 for supplying an output side signal for controlling the area of the orifice 10 of the logic valve LV in response to the pumped hydraulic pressure (P1).

As shown in FIG. 4, the aforementioned sequence valve 25 has an output side connected with a pump port 11A to which hydraulic oil discharged from the pump 1 is supplied, and a piston pressure chamber 8 of a logic valve LV. A port 12A, a plurality of drain ports 18A are formed, a housing 40 having a through hole 24 formed in the center thereof, and a permeable insertion into one side of the through hole 24, and one side of the high pressure side control valve. (2) a pilot piston (19) in communication with the pilot flow path (23) branching off the pilot flow path of the high-pressure side control valve so as to function the pilot pressure (Pi) for driving, and a hollow portion formed inside the pilot piston (19). (26), a piston (22) perturbed into one end of the hollow portion (26), a rod (27) fixed to the other side of the piston (22) and extending to the other side, and a hollow portion ( 26 is perturbably inserted into the other end of the guide 20 and the other end is protruded out of the piston 19 and the high pressure side working device inside the hollow part 26. (3) means for recognizing the pilot pressure Pi ₁ driven, and is fixedly inserted into the other side of the through-hole 24, and communicated with the input side passage 11, output side passage 12 and the return passage 18, respectively A sleeve 14 having a pump port 11A, an output side port 12A, and a drain port 18A formed therein and perturbably inserted into the sleeve 14, one end of which is a guide 20 of the pilot piston 19. And the other end is formed at one end of the spool 13 elastically supported by the return spring 15 and the pump port 11A and the drain port 18A of the sleeve 14. An inner passage 30 which prevents the pump port 11A from communicating with the drain port 18A and increases the communication area with the output side port 12A in proportion to the movement of the spool 13 from the initial state of communication; The plug 28, which is fixed to the other end of the through-hole 24 of the 40, supports the other end of the return spring 15, and the spool 13 is initialized against the pilot pressure Pi. Further included is a means for feedback state transition.

The above-described piston 22 may move inside the through hole 24 within the range of the movement stroke up to S1, and the guide 20 may move inside the hollow part 26 within the range of the movement stroke up to S2.

The aforementioned recognition means is provided between the piston 22 and the guide 20 to elastically bias the piston 22 to maintain the stroke ending state on one side, and the guide 20 to maintain the stroke ending state on the other side. It is configured to include an elastic member 21 for maintaining a predetermined interval between the other end of the rod 27 and one end of the guide 20.

The elastic force of the above-mentioned elastic member 21 restricts the opening area of the supply passage 9A of the low pressure side control valve 5 to which the hydraulic oil discharged from the hydraulic pump 1 is supplied, and thus the low pressure side working device 6 and The pilot pressure acting on the cross-sectional area of the pilot piston 19 when the pressure to the output side port 12A of the sequence valve 25 which drives the logic valve LV so as to operate the high pressure side work device 5 simultaneously is formed. It is set equal to the driving force F1 by Pi).

The elastic force of the elastic member 21 described above is set larger than the elastic force of the return spring 15, so that when the pilot pressure Pi acts through the pilot flow path 23, the return spring 15 is first contracted to spool ( 13) is activated to move.

The above-mentioned feedback means is formed in the spool 13 and is protruded from the inner diameter chamber 32 and the plug 28 communicated with the inner passage 30, and one end of the projection portion (1) inserted into the inner diameter chamber 32 ( 16) is configured.

Hereinafter, the operation of this embodiment configured as described above will be described.

In order to clarify the operation of the present embodiment, when the pilot pressure Pi acting on the sequence valve 25 is increased, the pilot piston is divided into three stages based on the state in which the pressure of the output side port 12A is changed. Force due to the sum of the elastic force FS2 of the elastic member 21 of the elastic member 21, the pressure P1 acting on the inner diameter chamber 32 of the spool 13 and the elastic force FS1 of the return spring 15 (hereinafter, , The first step of equilibrium with the 'repulsive force (Fr)'), the driving force (F2) and the repulsive force (Fr) by the pilot pressure (Pi) acting on the piston 22 of the pilot piston 19 ) And a second step of forming an equilibrium state, and when the driving force F2 is greater than the repulsive force Fr, it is a third step of obtaining an equilibrium state again, and each step proceeds sequentially.

First, the state proceeding from the initial state to the first step will be described in detail. As shown in FIG. 5 (a), the initial state is that the spool 13 is in the stroke ending state to the left by the return spring 15. One end of the spool 13 pushes the guide 20 to the left, and the pilot piston 19 is in the stroke ending state to the left. At this time, the spool 13 is switched to a state in which the pump port 11A of the sleeve 14 communicates with the drain port 18A.

In this state, the pilot oil Pi, which drives the high pressure side control valve 2, is supplied to the pilot flow path 23 to multiply the cross-sectional area A1 of the pilot piston 19 by the pilot pressure Pi. When the driving force F1 is larger than the elastic force FS1 of the return spring 15, which is the repulsive force Fr, the pilot piston 19 and the spool 13 are moved to the right in the stroke S1 range. In this case, since the elastic force FS1 of the elastic member 21 is greater than the elastic force FS2 of the return spring 15, the elastic member 21 does not contract. As the spool 13 moves, the pump port 11A closes the open state of the drain port 18A and communicates with the internal passage 30 communicating with the output side port 12A of the spool 13, thereby causing the internal passage. The pump pressure P1 of the pump port 11A acts on the inner diameter chamber 32 in communication with 30. At this time, the repulsive force Fr acting on the spool 13 is equal to the force F2 by the product of the cross-sectional area A2 of the inner diameter chamber 32 and the pump pressure P1, and the elastic force FS2 of the return spring. If the repulsive force Fr is greater than the elastic force FS1 of the elastic member 21, the spool 13 pushes the guide 20 and the movement distance S2 at which the guide 20 contacts the rod 27. Will be left again within (see Fig. 2 (c)). This state assumes that the pilot pressure Pi rises and the driving force F1 is greater than the elastic force FS1 of the elastic member 21. If the driving force F1 is less than the elastic force FS1, the pilot piston 19 ) Will be left.

As a result, when the elastic member 21 is contracted and the spool 13 is left as described above, the equilibrium state of the force is expressed by a formula,

FS1 = FS2 + P1A2

The prerequisite is FS1 PiA1. Therefore, in Equation 2, the variable is P1, and the operating pressure discharged from the pump and P1 is proportional to the opening area of the pump port 11A and the inner passage 30, so if the pump discharge pressure is constant, the caries in equation 2 The moving position of the spool 13 having the opening area of the inner passage 30 is determined to maintain the same value as.

In this state, the larger the discharge pressure of the pump 1 is, the larger the FS2 + P1A2 FS1 is, and the spool is turned left to minimize the opening area. In addition, the guide 20 is to be switched to the state of Fig. 5 (c) by omitting the state of Fig. 5 (b) from the state of Fig. 5 (a), after all, the high-pressure side working device is operated after operation This minimizes the time delay so that the low pressure side work tool and the high pressure work tool are operated simultaneously. At this time, if the elastic force FS1 of the elastic member 21 is set equal to the pilot pressure for initially driving the high load work device, as shown in the diagram B of FIG. 6, the pressure line of the output side port 12A at Pi ₁ is It will rise up to the set elastic force FS1 of the elastic member 21 in parallel with a Y-axis.

Next, the state proceeding from the first step to the second step will be described in detail. In the state in which the pilot pressure continues to rise so that the driving force F1 has the same value as the elastic force of the elastic member 21, the piston Pi may be the piston ( 22) has an area (A3) the driving force (F2) in a period Pi Pi _{2 1} B of the lead in the state of Figure 6 to have a value equal to the reaction force (Fr) acting on the.

In other words,

PiA3 = (P1A2 + FS2)

The pilot pressure with is Pi ₂ . In this state, the spool 13 does not move and is merely in a stopped state.

Finally, when the state proceeds from the second step to the third step, the pilot pressure Pi continues to increase so that the driving force F2, which is the left side of the equal sign in Equation 3, overcomes the repulsive force Fr, which is the right side of the equal sign. At this time, the piston 22 moves to the right by sliding the inner wall of the hollow portion 26 inside the pilot piston 19, whereby the guide 20 in contact with the rod 27 is the range of the moving stroke (S2) As the spool 13 moves, the communication area between the pump port 11A and the output side port 12A increases, resulting in an increase in the pressure of the output side port 12A. In addition, when the pressure of the output side port 12A rises, the repulsive force Fr rises, and when the repulsive force Fr beats the driving force F2, the spool 13 will again turn left. Therefore, since the spool 13 will continue to move in search of the tracking point at which the driving force F2 and the repulsive force Fr become equal, the spool 13 will eventually reach the state of FIG. 5 (c) to FIG. 20) Stroke S2) In this state, the pilot position Pi and the pump discharge pressure P1 of the output side port 12A are fed back and the moving position of the spool 13 is automatically converted. Will be done.

As described above, according to the variable priority device according to the present invention, the high pressure side control valve recognizes the pilot pressure at the set pressure at which the high pressure side working device can be operated, and the low pressure side working device is driven until the set pressure is reached. It supplies the control pressure to the logic valve so as to control the area of the orifice of the logic valve by feeding back the hydraulic pressure pumped from the pump to minimize the time delay in which the high pressure side work device is operated after the low pressure side work device is operated. The device and the high-pressure working device are operated at the same time, thereby improving the working efficiency of the equipment.

Claims (6)

In a variable priority device having a logic valve installed in a pump passage of a low pressure side control valve in a hydraulic line in which a plurality of work devices are driven by one pump and blocking the pump passage in proportion to a predetermined signal: And a sequence valve for recognizing a pilot pressure capable of operating the high pressure side work device and receiving an operating hydraulic pressure pumped from the pump to supply an output signal for controlling an area of an orifice of the logic valve. Variable Priority. The method according to claim 1, The sequence valve, A pump passage through which the hydraulic oil discharged from the pump is supplied, an output side passage connected to the logic valve, and a plurality of drain passages, the housing having a through hole at the center thereof; A pilot piston inserted into one side of the through hole in a perturbable manner and in communication with a pilot flow path of the high pressure side control valve such that one side functions as a pilot pressure for driving the high pressure side control valve; A hollow part formed inside the pilot piston; A piston removably inserted into one end of the hollow part; A rod fixed to the other side of the piston and extending to the other side; A guide inserted into the other end of the hollow part in a perturbable manner, the other end of which protrudes outward from the piston; Means for recognizing a pilot pressure in which the high pressure side work device is driven in the hollow part; A sleeve fixedly inserted into the other side of the through hole, the pump port having an angle in communication with the pump passage, the output side passage, and the drain passage; A spool which is perturbably inserted in the sleeve, one end of which is in contact with the guide of the pilot piston, and the other end of which is elastically supported by a return spring; An internal passage formed at one end of the spool to block the pump port from communicating with the drain port in proportion to the movement of the spool from an initial state of communicating the pump port with the drain port of the sleeve and to increase the communication area with the output side port; ; A plug fixed to the other end of the through hole of the housing to support the other end of the return spring; And And a feedback means for switching said spool to an initial state against said pilot pressure. The method according to claim 2, wherein the recognition means, It is installed between the piston and the guide to maintain the piston in a stroke ending state to one side, and to elastically bias the guide to maintain the stroke ending state to the other side to maintain a predetermined interval between the other end of the rod and one end of the guide Variable priority device comprising an elastic member. The method according to claim 3, wherein the elastic force of the elastic member, The sequence pilot pressure when the pressure is generated at the sequence output port for driving the logic valve to limit the opening area of the pump passage on the low pressure side to operate the low pressure side working device and the high pressure side working device at the same time is the pilot. Variable priority device characterized in that it is set equal to the force acting on the cross-sectional area of the piston. The method according to claim 2, wherein the feedback means, An inner diameter chamber formed in the spool and communicating with the inner passage; And And a protruding portion of the inner diameter chamber having one end protruding from the plug. The method of claim 2, wherein as the pilot pressure acting on the sequence valve is increased, A first step in which the elastic force of the elastic member of the pilot piston and the sum of the pressure acting on the inner diameter chamber of the spool and the elastic force of the return spring are in equilibrium; A second step of forming an equilibrium state with a sum of a pilot pressure acting on the piston of the pilot piston, a pressure acting on the inner diameter chamber of the spool, and an elastic force of the return spring; When the pilot pressure acting on the piston of the pilot piston overcomes the sum of the pressure acting on the inner diameter chamber of the spool and the elastic force of the return spring, a third step of obtaining an equilibrium state is sequentially performed. .