JP3946510B2 - Electric relief valve - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an electric relief valve provided with a solenoid.
[0002]
[Prior art]
When trying to electrify the hydraulic system with a hydraulic excavator or the like, an electric relief valve for controlling the system pressure by electrically controlling a conventional main relief valve can be considered.
[0003]
FIG. 6 is a simplified hydraulic circuit showing the common piping of the hydraulic excavator. In the attachment circuit of the hydraulic excavator, an electric relief valve is used for pressure control of the attachment circuit.
[0004]
An attachment circuit 13 is connected to the hydraulic pump 11 via a control valve 12. The attachment circuit 13 is provided with a plurality of electric relief valves 15 and an electric check valve 16 in the passage to the tank 17 so as to be compatible with various attachments 14.
[0005]
That is, the operator in the cab of the excavator switches the circuit from the cab (single-acting, double-acting, using one pump, using two pumps) by electrically switching these electric relief valve 15 and electric check valve 16. ) And relief pressure can be changed.
[0006]
In addition, the control valve 12 includes a pilot-operated spool 18 for controlling the hydraulic actuator 14a of the attachment 14, and a line relief with a make-up function that enables a make-up operation when a vacuum occurs in the circuit. Valve 19 is installed.
[0007]
When the spool 18 in the control valve 12 is in the neutral position, when the external force acts on the hydraulic actuator 14a of the attachment 14 and the closed oil in the attachment circuit 13 becomes high pressure, the line relief valve 19 The circuit pressure in the attachment circuit 13 is limited to the relief pressure set by the spring.
[0008]
This line relief valve 19 also has a make-up function. When the spool of the spool 18 is neutral, an external force is applied to the hydraulic actuator 14a, and the piston of the hydraulic actuator 14a moves. Therefore, the inside of the hydraulic actuator 14a becomes a vacuum.
[0009]
When the vacuum is generated, the makeup function is activated, and the return oil to the tank 17 is supplied to the vacuum generating portion of the hydraulic actuator 14a to eliminate the vacuum.
[0010]
The electric relief valve 15 is disclosed in Japanese Patent No. 3069515. This will be described with reference to FIG. 7. A main poppet 22 is slidably provided inside the valve body 21. The seat body 26 is fixed by an adapter 25 that is pressed against the main seat 24 by the spring 23 and screwed into the inside of the valve body 21, and slides into the adapter 25 so as to face the pilot seat 27 of the seat body 26. A pilot poppet 28 that is movably fitted is provided so as to be movable back and forth. A solenoid 29 that moves the pilot poppet 28 in the axial direction is attached to the valve body 21.
[0011]
As shown in FIG. 8, the solenoid 29 outputs a rightward thrust generated in proportion to a current value supplied to a built-in solenoid coil (not shown) to the movable part 30, and this movable part The pilot poppet 28 is pressed against the pilot seat 27 by 30.
[0012]
An inlet port 31 provided at the tip of the valve body 21 is communicated with a spring chamber 33 via an orifice 32 provided in the main poppet 22, and the spring chamber 33 is provided with an orifice 34 provided in the seat body 26, And through a pilot seat 27 opened by the retracted pilot poppet 28, a through hole 35 provided in the adapter 25, a passage 36 provided along the outer peripheral surface of the adapter 25, and a through hole 37 provided in the valve body 21. It communicates with the tank 17.
[0013]
The valve body 21 is provided with a tank port 38 that communicates with the inlet port 31 when the main poppet 22 is separated from the main seat 24. The main poppet 22 is provided with a filter 39 on the inlet side of the orifice 32.
[0014]
Next, the operating principle of this conventional electric relief valve 15 will be described.
[0015]
First, the solenoid 29 presses the tip of the pilot poppet 28 against the pilot seat 27 of the seat body 26 with a thrust F ₁ proportional to the current value I. It is assumed that the solenoid thrust F ₁ and the current value I at this time have a proportional relationship shown in FIG.
[0016]
(Formula 1)
F ₁ = k ₁ · I
However, _{k 1} is a proportionality constant.
[0017]
The pressure receiving area at the tip of the pilot poppet 28 seated on the pilot seat 27 of the seat body 26 is Ap, and the pressure receiving area upstream and downstream of the orifice 32 of the main poppet 22 is Am. Further, the preset load of the spring 23 and F _2.
[0018]
When the inlet pressure Pin of the inlet port 31 is lower than F ₁ / Ap, since the pilot seat 27 is closed by the pilot poppet 28, the inlet pressure Pin and the pressure in the spring chamber 33 are balanced at the same pressure. Therefore, the main poppet 22 is brought into close contact with the main seat 24 by the spring 23, and the inlet port 31 and the tank port 38 are blocked by the main poppet 22.
[0019]
Next, the inlet pressure Pin increases,
(Formula 2)
Pin = F ₁ / Ap
Then, the pilot poppet 28 is pushed rightward, the pilot seat 27 is opened, the orifice 32 from the inlet port 31, the spring chamber 33, the orifice 34 of the seat body 26, the pilot seat 27, the through hole 35, the passage The pilot flow rate Q ₁ flows into the tank 17 through 36 and the through hole 37.
[0020]
For convenience, when the tank pressure = 0, wherein since the pilot flow rate Q ₁ is flowing through the orifice 32 incorporated in the main poppet 22, the differential pressure ΔP of the orifice 32 represented by the following formula 3 is generated.
[0021]
(Formula 3)
Q ₁ = k ₂ · A ₃ · (ΔP) ^1/2
Here, k ₂ is a constant, and A ₃ is the opening cross-sectional area of the orifice 32.
[0022]
When F ₂ ≦ Am · ΔP with respect to the preset load F ₂ of the spring 23, the main poppet 22 is pushed to the right, the inlet port 31 and the tank port 38 are electrically connected, and the formula 2 Is preserved.
[0023]
In other words, according to Equations 1 and 2, the electric relief valve 15 can arbitrarily set the inlet pressure Pin by the current value I. When the electric check valve 16 is in the communication state in FIG. 6, the relief pressure of the attachment circuit 13 is set. Settings can be changed arbitrarily.
[0024]
Further, when the current value I supplied to the solenoid coil of the solenoid 29 is set to 0, the inlet pressure Pin is also set to 0. Therefore, when the electrical check valve 16 is in the communication state, the attachment circuit 13 is controlled to the unload state. .
[0025]
As described above, the electric relief valve 15 includes the main portion and the pilot portion, and the pilot poppet 28 is pressed against the pilot seat 27 by the solenoid 29 instead of the spring.
[0026]
Therefore, when no current is supplied to the solenoid coil of the solenoid 29, the thrust that presses the pilot poppet 28 against the pilot seat 27 cannot be obtained, so the pilot poppet 28 is opened by the pressure acting on the tip of the pilot poppet 28, and the inlet The pilot pressure introduced into the spring chamber 33 on the opposite side of the main poppet 22 from the port 31 through the orifice 32 (so-called back pressure of the main poppet 22) decreases, and the main poppet 22 opens and acts on the inlet port 31. Unload system pressure.
[0027]
On the other hand, when current is supplied to the solenoid coil of the solenoid 29, the pilot poppet 28 closes the pilot passage, so the main poppet 22 closes due to the increase in the back pressure of the spring chamber 33, so the system pressure rises and the pilot pressure increases. The force generated by the pilot pressure acting on the seat area of the pilot poppet 28 seated on the seat 27 and the pressure of the solenoid 29 are balanced.
[0028]
When the thrust of the solenoid 29 is applied as shown in FIG. 8, the system pressure acting on the inlet port 31 also increases in response to the current.
[0029]
[Problems to be solved by the invention]
In such a conventional electric relief valve 15, when an excessive surge current is generated in the electric input to the solenoid 29, the thrust of the solenoid 29 also increases according to the current, so that the relief pressure may rise abnormally. .
[0030]
The present invention has been made in view of these points, and an object of the present invention is to provide an electric relief valve that can prevent an abnormal increase in the relief pressure even when an excessive current is input.
[0031]
[Means for Solving the Problems]
According to the first aspect of the present invention, there is provided a main valve that can be opened and closed between a passage to be pressure controlled and a tank, and a passage from the pressure control subject to the side opposite to the main valve. It is interposed between the pilot valve that controls the introduced pilot pressure, the solenoid that has a movable part that drives the pilot valve in the pilot pressure closing direction when energized, and the movable part of the solenoid and the pilot valve. And a cover that is formed separately from the main body of the solenoid on the opposite side of the spring and joined by a bolt, and a stroke limiter that restricts the moving stroke of the movable part of the solenoid . One engaging part fitted to the movable part in the inner space so as to be movable and adjustable, a screw for fixing the one engaging part to the movable part, a main body part of the solenoid and a cap Electrical relief with the engaging plate, which is clamping fixed between the over, and the other of the engaging portion for engaging one of the engaging portion by the movement of the predetermined stroke of the engaging portion of one provided engaging plate Even if an excessive current such as surge current is input to the solenoid, the stroke limiter regulates the moving stroke of the moving part of the solenoid, so the force that acts on the pilot valve via the spring from the moving part of the solenoid The force that drives the pilot valve in the pilot pressure confinement direction is also restricted, and when this force is excessive, the relief pressure of the passage subject to pressure control controlled by the main valve can be prevented from rising abnormally. In addition, the stroke limiter removes the cover from the solenoid body, loosens the screw, and adjusts the fixed position of one engaging part relative to the movable part of the solenoid. This stroke limiter is engaged with this one engaging portion and the other engaging portion provided around the hole of the engaging plate that is clamped and fixed between the main body portion of the solenoid and the cover. Ru can be arbitrarily adjusted movement stroke of the movable portion which is regulated by.
[0032]
請 Motomeko 2 invention described in includes a valve body, the interior of the valve body, a main valve provided openably between the passage and the tank comprising a pressure control target, from the passage to be pressure controlled object a solenoid having a pilot valve for controlling a pilot pressure introduced into the opposite side of the pair to the main valve in this passage, the movable part to drive the pilot pressure closed write direction pilot valve when energized in the main body portion, the solenoid A spring interposed between the movable part of the pilot valve and the pilot valve, a spacer interposed between the valve main body and the main body of the solenoid and coupled by a bolt, and a hole drilled in the center of the spacer and fitted with the spring A spring fitting hole, a spring receiving body that is pressed by the movable part of the solenoid to compress the spring, and a stroke limiter that regulates the moving stroke of the movable part of the solenoid. And, the stroke limiter, while engagement of the outer diameter is formed in a flange shape in the spring receiving member by forming such that the large diameter of the spring receiving member than the inner diameter of the spring fitting hole drilled in the spacer An electric relief valve comprising a coupling portion and a spacer, the other engagement portion provided at a position engageable with one engagement portion by a predetermined stroke movement of one engagement portion, and a solenoid Even if an excessive current, such as a surge current, is input to the stroke limiter, the stroke limiter regulates the moving stroke of the moving part of the solenoid. Therefore, the force that acts on the pilot valve from the moving part of the solenoid via the spring is restricted. The force that drives the valve in the pilot pressure confining direction is also restricted, and when this force is excessive, the relief pressure of the passage subject to pressure control controlled by the main valve is reduced. Can always prevent the risk of increasing further, a spring receiving member for compressing the spring are pressed by the movable portion of the solenoid, the opposed position of the spring receiving body and engageable spacer side, one engagement of the stroke limiter Since the joint portion and the other engaging portion are provided, the existing solenoid can be used as it is.
[0033]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the present invention will be described in detail with reference to one embodiment shown in FIGS. 1 to 4 and another embodiment shown in FIG. In addition, the same code | symbol is attached | subjected to the part similar to the conventional electric relief valve shown by FIG. 7, and the description is abbreviate | omitted.
[0034]
FIG. 1 shows an electric relief valve 15 with a built-in mechanical function that keeps the pressure below a certain value even when an excessive current such as a surge current is input.
[0035]
In the electric relief valve 15, a main poppet 22 as a main valve provided in an openable manner between the passage 41 to be pressure controlled and the tank 17 inside the valve body 21, and a passage 41 to be pressure controlled. The pilot poppet 28 as a pilot valve for controlling the pilot pressure introduced into the spring chamber 33 on the opposite side of the main poppet 22 with respect to the passage 41 through the orifice 32 is incorporated, and the pilot poppet 28 is closed with the pilot pressure. The configuration having the solenoid 29 driven in the insertion direction is the same as the conventional one shown in FIG.
[0036]
Further, a hollow spacer 44 is interposed between the body portion 42 of the solenoid 29 and the flange portion 43 of the valve body 21, and the body portion 42 and the spacer 44 of the solenoid 29 are coupled by a bolt (not shown). The spacer 44 and the flange portion 43 of the valve body 21 are coupled by another bolt (not shown).
[0037]
Between the movable part 30 of the solenoid 29 and the pilot poppet 28, a spring 47 having an appropriate spring constant formed in a coil shape is interposed. One end of the spring 47 is fitted with one spring receiving body 48 as a member for compressing the spring 47 in contact with the movable portion 30 of the solenoid 29, and the other end of the spring 47 is fitted with The other spring receiver 49 that is in contact with the pilot poppet 28 is fitted.
[0038]
Inside the solenoid 29, a stroke limiter 51 for restricting the moving stroke of the movable part 30 is incorporated.
[0039]
The solenoid 29 includes a solenoid coil 52 inside the main body 42, an armature 53 that is moved by an axial thrust according to the amount of current when the solenoid coil 52 is energized, and a shaft-shape integrated with the armature 53. The movable part 30 is driven in a direction in which the movable part 30 protrudes from the main body part 42 when the solenoid coil 52 is energized.
[0040]
On the other hand, the stroke limiter 51 of the solenoid 29 has one engaging portion 55 on the movable portion 30 in an inner space portion of a cover 54 that is formed separately from the main body portion 42 and joined by a bolt (not shown). It is fitted so that the movement can be adjusted, and is fixed to the movable portion 30 by a screw 56.
[0041]
Further, an engagement plate 57 is clamped and fixed between the main body portion 42 and the cover 54. A hole through which the movable portion 30 passes is provided at the center of the engagement plate 57, and the other engagement portion 58 is provided around the hole, and one of the engagement portions 55 is moved by a predetermined stroke st. The engaging portion 55 can be locked by the other engaging portion 58.
[0042]
Next, the function and effect of this embodiment will be described.
[0043]
When no current is supplied to the solenoid coil 52 of the solenoid 29, a thrust force that presses the pilot poppet 28 against the pilot seat 27 cannot be obtained. Therefore, as shown in FIG. 2, the pilot poppet 28 acts on the tip portion thereof. The oil flows out from the spring chamber 33 to the tank 17 through a series of pilot passages including the orifice 34 of the seat body 26, the pilot seat 27, the through hole 35, the passage 36, and the through hole 37. Since the pilot pressure (so-called back pressure) introduced into the spring chamber 33 on the opposite side of the main poppet 22 through 32 is reduced and the main poppet 22 is separated from the main seat 24, the system of the passage 41 acting on the inlet port 31 The pressure is unloaded from the tank port 38 into the tank 17.
[0044]
On the other hand, when a current is supplied to the solenoid coil 52 of the solenoid 29, the movable part 30 moves to the right as shown in FIG. 3 and reaches a position where a pressing force corresponding to the thrust generated according to the current value is obtained. The pilot poppet 28 is given the same thrust as the thrust generated by the solenoid 29 until the spring 47 is stroked while being compressed and one engaging portion 55 is engaged with the other engaging portion 58.
[0045]
At this time, since the pilot poppet 28 closes the pilot passage with a force corresponding to the thrust generated by the solenoid 29, the back pressure of the spring chamber 33 rises and the main poppet 22 operates in the closing direction. For this reason, the system pressure in the passage 41 rises and balances with a pressure that makes the force generated in the seat area of the pilot poppet 28 equal to the thrust of the solenoid 29. The system pressure in the passage 41 is set as a relief pressure.
[0046]
Therefore, as shown by the inclined portion in FIG. 4, the relief pressure of the passage 41 increases in accordance with the current value as in the conventional electric relief valve.
[0047]
As shown in FIG. 3, the moving stroke of the movable portion 30 reaches a predetermined stroke st regulated by the stroke limiter 51, and the one engaging portion 55 and the other engaging portion 58 are engaged, and the movable portion When the movement of 30 is restricted, the thrust applied to the spring 47 does not increase beyond a certain value even if the current value supplied to the solenoid coil 52 increases. A constant thrust is held by the spring 47.
[0048]
Therefore, in this state, even if an excessive surge current is input to the solenoid coil 52, the movable part 30 cannot move, so that the thrust applied to the pilot poppet 28 is applied from the compressed spring 47 shown in FIG. Is limited to a certain value and does not rise any further.
[0049]
For this reason, as shown in the horizontal portion of FIG. 4, the relief pressure does not rise above a certain value, and a surge cut function is obtained.
[0050]
In other words, even if a surge current is input to the solenoid coil 52 of the solenoid 29, the stroke limiter 51 regulates the moving stroke of the movable portion 30 of the solenoid 29, so that the pilot poppet 28 is moved from the movable portion 30 of the solenoid 29 via the spring 47. The force acting on the pilot poppet 28 is restricted, and the force that drives the pilot poppet 28 in the pilot pressure closing direction is also restricted. If this force is excessive, the relief pressure of the passage 41 controlled by the main poppet 22 will also rise abnormally. , Can prevent that fear.
[0051]
According to the embodiment shown in FIG. 1, the cover 54 is removed from the body portion 42 of the solenoid 29, the screw 56 is loosened, and the fixed position of the one engaging portion 55 with respect to the movable portion 30 is moved and adjusted. Then, the moving stroke st of the movable part 30 regulated by the stroke limiter 51 can be arbitrarily adjusted.
[0052]
Next, FIG. 5 shows another embodiment.
[0053]
A stroke limiter 61 that restricts the moving stroke of the movable portion 30 of the solenoid 29 is provided between the spring receiver 48 and the spacer 44.
[0054]
That is, this stroke limiter 61 is provided with one engaging portion 62 formed in a flange shape on one spring receiving body 48 as a member that is pressed by the movable portion 30 of the solenoid 29 to compress the spring 47, Further, the spacer 44 is provided with the other engagement portion 63 at a position where the engagement portion 62 can be engaged by the movement of the one engagement portion 62 by a predetermined stroke st.
[0055]
In short, the predetermined stroke of one engaging portion 62 is formed by forming the outer diameter of the spring receiving body 48 larger than the inner diameter of the spring fitting hole 64 formed in the central portion of the spacer 44. The one engaging portion 62 and the other engaging portion 63 are engaged by the movement of st.
[0056]
Thus, in the electric relief valve 15, the movable portion 30 of the solenoid 29 and the pilot poppet 28 are connected by the spring 47 having an appropriate spring constant, and the thrust of the solenoid 29 is transmitted via the spring 47 to the pilot poppet. It has the structure given to 28. Further, a stroke limiter 61 is provided on a member driven by the movable portion 30 of the solenoid 29, and the movable portion 30 of the solenoid 29 is restricted so as not to move beyond a predetermined stroke st.
[0057]
Since the valve structure of the electric relief valve 15 shown in FIG. 5 is the same as that shown in FIG. 1, the same reference numerals are given to the same parts and the description thereof is omitted.
[0058]
Next, the operation of the embodiment shown in FIG. 5 will be described.
[0059]
The value of the current supplied to the solenoid coil of the solenoid 29 increases, the moving stroke of the movable part 30 of the solenoid 29 reaches a predetermined stroke st regulated by the stroke limiter 61, and one engagement part 62 engages the other. When engaged with the portion 63, the thrust applied to the spring 47 does not increase beyond a certain value even if the current value supplied to the solenoid coil further increases. A constant thrust is held by the spring 47.
[0060]
Therefore, even if an excessive surge current is input to the solenoid coil of the solenoid 29 and an excessive thrust is generated in the solenoid 29, the thrust applied to the pilot poppet 28 does not rise above a certain value.
[0061]
For this reason, as shown in the horizontal portion of FIG. 4, the relief pressure does not rise above a certain value, and a surge cut function is obtained.
[0062]
In other words, even if a surge current is input to the solenoid 29, the stroke limiter 61 regulates the moving stroke of the movable part 30 of the solenoid 29, so that it is applied to the pilot poppet 28 from the movable part 30 of the solenoid 29 via the spring 47. The force that drives the pilot poppet 28 in the pilot pressure closing direction is also regulated, and if this force is excessive, the relief pressure of the passage 41 that is the target of pressure control controlled by the main poppet 22 also rises abnormally However, this can be prevented.
[0063]
According to the embodiment shown in FIG. 5, one spring receiver 48 that is pressed by the movable portion 30 of the solenoid 29 to compress the spring 47, and the side of the spacer 44 that can be engaged with the spring receiver 48. Since one engaging portion 62 and the other engaging portion 63 of the stroke limiter 61 are provided at the opposite positions, the existing solenoid 29 can be used as it is.
[0064]
【The invention's effect】
According to the first aspect of the present invention, even if an excessive current, for example, a surge current, is input to the solenoid, the stroke limiter regulates the moving stroke of the movable portion of the solenoid. The force acting on the valve is regulated, the force that drives the pilot valve in the pilot pressure closing direction is also regulated, and when this force is excessive, the relief pressure of the passage subject to pressure control controlled by the main valve becomes abnormal In addition, the stroke limiter removes the cover from the solenoid body, loosens the screw, moves and adjusts the fixed position of one engagement portion with respect to the movable portion of the solenoid, The engaging portion is engaged with the other engaging portion provided around the hole of the engaging plate that is clamped and fixed between the main body portion of the solenoid and the cover. , Ru can be arbitrarily adjusted movement stroke of the movable portion which is regulated by the stroke limiter.
[0065]
According to the invention 請 Motomeko 2, an excessive current to the solenoid, for example, even if a surge current is inputted, the stroke limiter restricts the movement stroke of the movable part of the solenoid, through the spring from moving parts of the solenoid The force acting on the pilot valve is restricted, and the force that drives the pilot valve in the pilot pressure closing direction is also restricted. When this force is excessive, the relief pressure of the passage subject to pressure control controlled by the main valve is abnormal. In addition, there is one engagement of the stroke limiter between the spring receiver that is pressed by the moving part of the solenoid and compresses the spring, and the opposing position on the spacer side that can be engaged with the spring receiver. Since the joint portion and the other engaging portion are provided, the existing solenoid can be used as it is.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view showing an embodiment of an electric relief valve according to the present invention.
FIG. 2 is a cross-sectional view of the electric relief valve when unloaded.
FIG. 3 is a cross-sectional view of the electric relief valve when the stroke limiter is operated.
FIG. 4 is a characteristic diagram showing current-relief pressure characteristics of the electric relief valve.
FIG. 5 is a cross-sectional view showing another embodiment of the electric relief valve according to the present invention.
FIG. 6 is a circuit diagram showing a hydraulic circuit in which an electric relief valve is incorporated.
FIG. 7 is a cross-sectional view showing a conventional electric relief valve.
FIG. 8 is a characteristic diagram showing current-thrust characteristics of a solenoid used in a conventional electric relief valve.
[Explanation of symbols]
17 tanks
21 Valve body
22 Main poppet as main valve
28 Pilot poppet as pilot valve
29 Solenoid
30 Moving parts
41 passage
42 Body
44 spacer
47 Spring
48 scan pulling receiving body
51 Stroke limiter
54 cover
55 One engaging part
56 screws
57 engagement plate
58 The other engaging part
61 Stroke limiter
62 One engaging part
63 The other engaging part
64 spring fitting hole

Claims (2)

A main valve provided to be freely opened and closed between a passage to be pressure controlled and a tank;
A pilot valve for controlling the pilot pressure introduced from the passage subject to pressure control to the opposite side of the main valve with respect to this passage;
A solenoid having a movable part inside the main body for driving the pilot valve in the pilot pressure closing direction when energized;
A spring interposed between the moving part of the solenoid and the pilot valve;
A cover that is formed separately from the main body of the solenoid on the opposite side of the spring and joined by bolts;
A stroke limiter that regulates the moving stroke of the moving part of the solenoid ;
Stroke limiter is
One engaging portion fitted to the movable portion so as to be movable and adjustable in the inner space of the cover;
A screw for fixing one engaging portion to the movable portion;
An engagement plate that is clamped and fixed between the main body of the solenoid and the cover;
An electric relief valve comprising: an engagement plate provided on an engagement plate; and the other engagement portion that locks one engagement portion by movement of one engagement portion with a predetermined stroke . A valve body;
A main valve provided inside the valve body so as to be openable and closable between a passage to be pressure controlled and a tank;
A pilot valve for controlling the pilot pressure introduced from the passage subject to pressure control to the opposite side of the main valve with respect to this passage;
A solenoid having a movable part inside the main body for driving the pilot valve in the pilot pressure closing direction when energized;
A spring interposed between the moving part of the solenoid and the pilot valve;
A spacer interposed between the valve main body and the main body of the solenoid and coupled by a bolt;
A spring fitting hole that is drilled in the center of the spacer and fits with the spring;
A spring receiver that is pressed by the movable part of the solenoid to compress the spring;
A stroke limiter that regulates the moving stroke of the moving part of the solenoid;
Stroke limiter is
One engaging portion formed in a flange shape on the spring receiver by forming the outer diameter of the spring receiver to be larger than the inner diameter of the spring fitting hole formed in the spacer ,
An electric relief valve comprising a spacer and the other engagement portion provided at a position engageable with one engagement portion by a predetermined stroke movement of the one engagement portion.

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