JPH1163283A - Assembly of poppet type electromagnetic proportioning valve - Google Patents

Abstract

PROBLEM TO BE SOLVED: To restrain generation of dispersion in the characteristics of a poppet type electromagnetic proportioning valve in its assembling method. SOLUTION: A poppet valve 22 which displaces according to balancing between electromagnetic force and energizing force is fitted, and a poppet type electromagnetic proportioning valve 10 is fitted, which changes the continuity condition of a passage 38 continuously by displacing the poppet valve 22. An electromagnetic coil for applying magnetic force to the poppet valve 22 is set at a prescribed position. By passing prescribed exciting current through the electromagnetic coil, the poppet valve 22 is displaced to yoke 24 side by a prescribed amount. High-pressure air under prescribed pressure is supplied to the upstream of the passage 38. A valve seat 36 is pressed in to poppet valve 22 side until the flow rate of air flowing through the passage 38 has reached its target value.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for assembling a poppet-type electromagnetic proportional valve, and more particularly, to a method for assembling a poppet-type electromagnetic proportional valve which is suitable for suppressing variation in characteristics of the poppet-type electromagnetic proportional valve.

[0002]

2. Description of the Related Art Conventionally, for example, Japanese Patent Application Laid-Open No. 8-27082
As disclosed in No. 3, a poppet type solenoid valve is known. The above-described conventional poppet type solenoid valve includes a valve seat for closing a flow path and a poppet valve. A plunger is fixed to the poppet valve. The plunger is urged toward the valve seat by a spring. Further, a yoke and an electromagnetic coil for generating an electromagnetic force opposing the urging force of the spring are disposed near the plunger.

In the above conventional poppet type solenoid valve, when no exciting current is supplied to the electromagnetic coil, the poppet valve sits on a valve seat. In this case, the poppet-type solenoid valve is in a closed state. On the other hand, when a predetermined exciting current is supplied to the electromagnetic coil, the plunger is drawn to the yoke, and the poppet valve is separated from the valve seat. In this case, the poppet type solenoid valve is in an open state. Therefore, according to the conventional poppet type solenoid valve, the open / close state can be switched according to whether or not a predetermined exciting current is supplied to the electromagnetic coil.

In the above conventional poppet type solenoid valve, when the poppet valve is seated on a valve seat, a clearance is formed between the yoke and the plunger. Hereinafter, this clearance is referred to as a fully closed clearance. The value of the exciting current required to open the poppet-type solenoid valve changes according to the above-described fully-closed clearance. In addition, the size of the flow path secured between the poppet valve and the valve seat in the open state is
It is determined by the above-described fully-closed clearance. For this reason, in order to stabilize the quality of the conventional poppet type solenoid valve, it is necessary to accurately manage the clearance when fully closed.

In the assembling process of the above-mentioned conventional poppet type solenoid valve, a series of processes described below are sequentially performed. Fixing the yoke inside the sleeve, inserting a spring into a recess provided in the yoke, inserting a plunger and a poppet valve into the sleeve so that one end of the spring contacts the plunger, And press-fitting the valve seat until the clearance between the yoke and the plunger at the time of full closure becomes a predetermined length in a state where the valve seat is in contact with the valve seat.

In the above process, the valve seat is press-fitted by the following method so that the clearance between the yoke and the plunger at the time of full closure can be accurately matched to a predetermined length. (i) Set the electromagnetic coil around the sleeve,
Supplying a predetermined exciting current to the electromagnetic coil, (ii)
A step of press-fitting the valve seat while monitoring the voltage between both ends of the electromagnetic coil, and (iii) a step of ending the press-fitting of the valve body when a pulse-like change occurs in the voltage between both ends of the electromagnetic coil.

When the above step (i) is performed, a predetermined electromagnetic force acts between the yoke and the plunger. This electromagnetic force increases as the distance between the two decreases. Therefore, when the press-fitting of the valve seat proceeds and the clearance at the time of full closing continues to decrease, the relationship of “electromagnetic force> biasing force” is eventually established. When the above relationship is established, the plunger is pulled toward the yoke at a stretch.

While the plunger is pulled toward the yoke at a stretch, the magnetic resistance of the magnetic circuit including the plunger and the yoke shows a sharp decrease. For this reason, when the above-mentioned displacement occurs in the plunger, the density of the magnetic flux penetrating the electromagnetic coil sharply increases. When the density of the magnetic flux passing through the electromagnetic coil rapidly increases, a pulse-like change appears at both ends of the electromagnetic coil due to electromagnetic induction. According to the above step (iii), the press-fitting of the valve seat is terminated when the change appears in the voltage between both ends of the electromagnetic coil.

Therefore, according to the above-described series of steps, the press-fitting of the valve seat can be terminated when the clearance at the time of the fully closed position accurately reaches the predetermined length. As described above, according to the conventional manufacturing method, it is possible to accurately manage the clearance at the time of the fully closed state and effectively suppress the variation in the characteristics of the poppet type solenoid valve.

[0010]

The above-mentioned conventional poppet type solenoid valve is a solenoid valve functioning as an on-off valve. Less than,
This type of poppet-type solenoid valve is particularly called a “poppet-type solenoid on-off valve”. On the other hand, as a poppet type electromagnetic valve, an electromagnetic valve that realizes an opening proportional to a supplied excitation current is known. Hereinafter, this type of poppet type solenoid valve is particularly referred to as a “poppet type solenoid proportional valve”.

The poppet-type electromagnetic proportional valve includes a plunger, a yoke, and a spring for urging the plunger and the yoke in a direction similar to the poppet-type electromagnetic on-off valve. The plunger and the yoke are configured such that the electromagnetic force acting between them is substantially proportional to the exciting current, and that the exciting current does not change rapidly when the clearance between the two increases or decreases.

The characteristics of the poppet type electromagnetic proportional valve are greatly affected by the size of the fully closed clearance as in the case of the poppet type electromagnetic on / off valve. Therefore, in the manufacturing process of the poppet-type electromagnetic proportional valve, it is necessary to precisely control the fully-closed clearance as in the case of the poppet-type electromagnetic on-off valve. By the way, the poppet-type electromagnetic proportional valve is configured such that when the clearance between the plunger and the yoke changes as described above, the electromagnetic force acting between the plunger and the yoke does not suddenly change. For this reason, for the poppet type electromagnetic proportional valve, a predetermined exciting current is supplied to the electromagnetic coil (see the above-described process).
(i)) Then, even if the valve seat is press-fitted (the above step (ii)), no pulse-like change occurs in the voltage across the electromagnetic coil. Therefore, with the above-mentioned conventional manufacturing method used for manufacturing a poppet-type electromagnetic on-off valve, it is not possible to accurately control the fully closed clearance of the poppet-type electromagnetic proportional valve.

The present invention has been made in view of the above points, and an object of the present invention is to provide a method of assembling a poppet-type electromagnetic proportional valve capable of accurately controlling the clearance when the poppet-type electromagnetic proportional valve is fully closed. Aim.

[0014]

The above object is achieved by the present invention.
As described in the above, a method for assembling a poppet-type electromagnetic proportional valve that includes a poppet valve that is displaced by a balance between an electromagnetic force and an urging force and that continuously changes a conduction state of a flow path by displacing the poppet valve. A first step of setting an electromagnetic coil for applying an electromagnetic force to the poppet valve at a predetermined position; a second step of flowing a predetermined exciting current through the electromagnetic coil; A third step of supplying a fluid having a predetermined pressure, and the poppet valve and a valve seat of the poppet valve such that a flow rate of the fluid flowing through the flow path has a value corresponding to the exciting current and the predetermined pressure. And a fourth step of adjusting the positional relationship with the poppet type electromagnetic proportional valve.

In the present invention, when the first step and the second step are performed, an electromagnetic force opposing the urging force acts on the poppet valve. When the above electromagnetic force acts on the poppet valve,
The poppet valve is displaced to a position where the electromagnetic force and the urging force balance. When the third step is performed, the fluid flows through the flow path secured between the valve seat and the poppet valve.
The flow rate of the fluid flowing through the flow path is determined by the relative position between the valve seat and the poppet valve and the pressure of the fluid supplied to the flow path.

The position of the poppet valve is determined by the exciting current flowing through the electromagnetic coil. Therefore, the flow rate of the fluid flowing through the flow path is determined by the value of the exciting current, the position of the valve seat, and
It is determined by the pressure of the fluid. In the present invention, the second
The value of the exciting current supplied in the step, the pressure of the fluid to be dinosaured in the third step, and the flow rate obtained for a proper combination of the valve seat position are stored. In the fourth step, the position of the valve seat is adjusted so that the amount of fluid flowing through the flow path matches the above flow rate. According to the above method, the position of the valve seat is adjusted to an appropriate position.

[0017]

FIG. 1 is a sectional view of a poppet type electromagnetic proportional valve 10 according to an embodiment of the present invention. The poppet type electromagnetic proportional valve 10 includes a sleeve 12. The sleeve 12 is a tubular member configured such that one end is a closed end. The sleeve 12 is made of a non-magnetic material. An electromagnetic coil 14 is provided around the sleeve 12. The electromagnetic coil 14 has an annular member 16. The annular member 16 is a member made of a magnetic material,
A gap portion 18 is provided on the inner peripheral side.

Inside the sleeve 12 is a plunger 20.
And a poppet valve 22 are housed. Plunger 2
0 is made of a magnetic material. On the other hand, the poppet valve 22
Is made of a non-magnetic material. The plunger 20 and the poppet valve 22 can slide inside the sleeve 12 integrally. A yoke 24 and a spring 26 are housed inside the sleeve 12. The yoke 24 is fixed inside the sleeve 12. The spring 26 urges the yoke 24 and the plunger 20 in the separating direction.

The plunger 20 has a projection 28 on a surface facing the yoke 24. On the other hand, the yoke 24 has a concave portion 30 on a surface facing the plunger 20. In the poppet type electromagnetic proportional valve 10, the plunger 20 can slide inside the sleeve 12 while securing a predetermined clearance between the outer peripheral surface of the convex portion 28 and the inner peripheral surface of the concave portion.

A core 32 is press-fitted into the opening of the sleeve 12. A through hole 34 that slidably holds the poppet valve 22 is formed in the center of the core 32. The poppet valve 22 is configured to pass through the through hole 34 and protrude from the through hole 34. A valve seat 36 is press-fitted into the core 32. A flow path 38 is formed inside the valve seat 36. The flow path 38 is closed when the poppet valve 22 is seated, and is opened when the poppet valve 22 is unseated. The core 32 is provided with a through hole 40 that opens on the side surface thereof. The through hole 40 is provided in the poppet valve 2.
When the valve 2 is separated from the valve seat 36, the channel 2 becomes conductive with the channel 38, and the poppet valve 22 is shut off from the channel 38 by sitting on the valve seat 36.

Hereinafter, the operation of the poppet type electromagnetic proportional valve 10 will be described. In the poppet type electromagnetic proportional valve 10,
When the exciting current is not supplied to the electromagnetic coil 14,
No electromagnetic force acts between the plunger 20 and the yoke 24. In this case, the poppet valve 22 is urged toward the valve seat 36 by the spring 26. Therefore, the electromagnetic coil 1
If no exciting current is supplied to the poppet valve 2,
2 is seated on the valve seat 36, and the flow path 38 and the through hole 40 are shut off.

When an exciting current is supplied to the electromagnetic coil 14, a magnetic flux that flows back and forth inside and outside the electromagnetic coil 14 is generated.
This magnetic flux flows through the annular member 16, the yoke 24 and the plunger 20 and returns. Yoke 24 and plunger 2
0, magnetic flux is generated via an air gap between the flat portion of the concave portion 30 and the flat portion of the convex portion 28 and an air gap between the outer peripheral portion of the concave portion 30 and the outer peripheral portion of the convex portion 28. At the same time, the magnetic flux is transmitted and received via an air gap between the side surface portion of the concave portion 30 and the side surface portion of the convex portion 28.

Of the magnetic flux flowing between the yoke 24 and the plunger 20, the magnetic flux passing through the air gap described above generates an electromagnetic force that draws the yoke 24 and the plunger 20. On the other hand, the magnetic flux passing through the air gap does not generate an electromagnetic force that draws the yoke 24 and the plunger 20. Accordingly, the electromagnetic force that draws the yoke 24 and the plunger 20, that is, the electromagnetic force that pulls the poppet valve 22 in the valve opening direction, increases as the magnetic flux passing through the above air gap increases.

In the process of displacing the plunger 20 toward the yoke 24 in the poppet type electromagnetic proportional valve 10, the air gap is reduced and the width of the air gap (the side surface of the convex portion 28 and the The width that the side surface overlaps) increases. In this case, the density of the magnetic flux flowing through the above air gap shows a gradual increase tendency as compared with the case where the above air gap does not exist.

FIG. 2 shows the relationship between the size of the air gap described above and the electromagnetic force that draws the plunger 20 and the yoke 24. The relationship shown in FIG. 2 is expressed using the exciting current supplied to the electromagnetic coil 14 as a parameter. In FIG. 2, in a region sandwiched by hatching (hereinafter, referred to as a use region), the plunger 20 and the yoke 2
4 and an exciting current supplied to the electromagnetic coil 14 have a substantially proportional relationship. Also,
In the above use area, the plunger 20 and the yoke 24
Does not show a large change with respect to a change in the air gap. Therefore, according to the poppet type electromagnetic proportional valve 10, when the air gap is included in the above use area, the air gap is located between the plunger 20 and the yoke 24.
An electromagnetic force proportional to the exciting current can be generated.

When an electromagnetic force acts between the plunger 20 and the yoke 24, the spring 26 is elastically deformed until an urging force balanced with the electromagnetic force is generated. The spring 26 generates an urging force proportional to the amount of elastic deformation. Therefore, when an electromagnetic force acts between the plunger 20 and the yoke 24, the spring 26 undergoes elastic deformation in proportion to the electromagnetic force. As a result, according to the poppet type electromagnetic proportional valve 10, the poppet valve 22 is connected to the electromagnetic coil 14.
Can be separated from the valve seat 36 by an amount proportional to the excitation current supplied to the valve seat 36.

As described above, according to the poppet type electromagnetic proportional valve 10, the poppet valve 22 can be provided with an opening proportional to the exciting current. A flow path corresponding to the degree of opening of the poppet valve 22 is secured between the flow path 38 and the through hole 40.
Therefore, according to the poppet type electromagnetic proportional valve 10, by controlling the exciting current, the flow rate of the fluid flowing from the flow path 38 to the through hole 40 can be accurately controlled.

The characteristics of the poppet type electromagnetic proportional valve 10 greatly affect the clearance secured between the plunger 20 and the yoke 24 when the poppet valve 22 is located at the fully closed position, that is, the fully closed clearance. Is done. For this reason, in order to stabilize the quality of the poppet type electromagnetic proportional valve 10, it is necessary to accurately manage the fully closed clearance.

In the poppet type electromagnetic proportional valve 10, the clearance when fully closed is determined by the position of the valve seat 36.
More specifically, it is determined by the press fitting depth of the valve seat 36 into the core 32. The present embodiment is characterized in that the valve seat 36 is press-fitted by the following assembling method in order to make the clearance at the time of fully closing exactly match the design value. Hereinafter, an assembling method of the present embodiment will be described with reference to FIGS.

FIG. 3 is a sectional view of the press-fitting device 42 of the valve seat 36 and the object 44 set in the press-fitting device 42. The processing object 44 is such that the yoke 24,
The plunger 20 and the core 32 are assembled, and the valve seat 36 is temporarily inserted into the opening of the core 32. The press-fitting device 42 includes an electromagnetic coil 46. A power supply circuit 48 is connected to the electromagnetic coil 46. Power supply circuit 48
Supplies a predetermined exciting current to the electromagnetic coil 46 at a predetermined timing under the control of the sequencer 50. A work table 52 is provided above the electromagnetic coil 46.
Are arranged. The processing target 44 is set on the work table 52 such that the yoke 24 and the plunger 20 housed in the sleeve 12 are surrounded by the electromagnetic coil 46.

A sealed case 54 is set on the work table 52. The sealed case 54 is provided with a fluid supply passage 56 and a fluid discharge passage 58. A pressing member 60 is inserted into the sealed case 54. The pressing member 60 can slide in the axial direction while keeping the sliding portion with the sealing case 54 liquid-tight. The pressing member 60 is used in a state where it is in contact with the end of the valve seat 36. The pressing member 60 has a flow path 62 on an end face that contacts the valve seat 36. The fluid supply passage 56 and the flow path 38 inside the valve seat 36 are maintained in a conductive state via the flow path 62 in a state where the pressing member 60 and the valve seat 36 are in contact with each other.

The fluid supply passage 56 is connected to a regulator 66 via an on-off valve 64. Regulator 66
Is supplied with high-pressure air. The regulator 66 is
Supplied to the on-off valve 64 the high-pressure air (hereinafter referred to as the regulator pressure P _RE) predetermined pressure regulating pressure by. The on-off valve 64 is a two-position solenoid valve that maintains a closed state in a normal state and is opened when a drive signal is supplied from the sequencer 50. When the on-off valve 64 is opened, the regulator pressure _PRE is supplied to the flow path 38 via the fluid supply path 56 and the flow path 62.

When the regulator pressure _PRE is supplied to the flow passage 38, the poppet valve 2 is supplied from the flow passage 38 to the fluid discharge passage 58.
Air flows at a flow rate corresponding to the opening degree of 2 and the regulator pressure _PRE . A flow meter 68 is connected to the fluid discharge passage 58. The flow meter 68 generates a signal corresponding to the flow rate of the high-pressure air discharged from the fluid discharge passage 58. Flow meter 68
Are supplied to the sequencer 50. Sequencer 50 detects the flow rate of air flowing through flow path 38 based on the output signal.

A load cell 70 and a servo press 72 are provided above the pressing member 60. The servo press 72 is controlled by the sequencer 50,
A predetermined pressing force is applied to the load cell 70 at a predetermined timing. The load cell 70 outputs an electric signal corresponding to the pressing force applied to the valve seat 36 via the pressing member 60. The pressing force generated by the servo press 72 is supplied to the valve seat 36 via the load cell 70 and the pressing member 60.

The sequencer 50 includes a data processing device 74
Is connected. The sequencer 50 performs the processing based on the detection result of the flow meter 68, the processing result of the data
A series of processing described later is executed so that the valve body 36 is press-fitted to an appropriate position. FIG. 4 is a flowchart showing the contents of a series of processes executed in the press-fitting device 42. The press-fitting device 42 press-fits the valve seat 36 by executing a series of processes shown in FIG. 4 after the activation switch is turned on. In the series of processes shown in FIG. 4, first, the process of step 100 is executed.

[0036] In step 100, processing to supply a predetermined current I ₀ from the power supply circuit 48 to the electromagnetic coil 46 is performed. When the processing of step 100 is executed,
A magnetic flux flowing between the plunger 20 and the yoke 24 is generated, and a predetermined electromagnetic force is generated between the two. As a result, the process of step 100 is performed, the plunger 20 and poppet valve 22, by a displacement amount corresponding to the current I ₀ is displaced to the yoke 24 side.

In step 102, a process for opening the on-off valve 64 is executed. When the process of step 102 is performed, high-pressure air with the regulator pressure _PRE is guided to the flow path 38. At the time when this step 102 is executed, a sufficiently large space is secured between the valve seat 36 and the poppet valve 22. Therefore, when the process of step 102 is executed, the fluid discharge passage 5
At 8, an amount of air flows according to the regulator pressure _PRE and the above-mentioned interval.

In step 104, the flow rate of the air discharged from the fluid discharge passage 58 is detected. Step 106
Then, it is determined whether or not the detected flow rate is equal to or less than the target flow rate. The target flow rate used in step 106 is
When the distance between the valve seat 36 and the poppet valve 22 is an appropriate value corresponding to the exciting current I ₀ , it is an appropriate flow rate of air generated for the regulator pressure _PRE . Therefore, when it is determined that the detected flow rate is not lower than the target flow rate, it can be determined that an excessive interval is secured between the valve seat 36 and the poppet valve 22. In this case, the process of step 108 is performed next.

In step 108, an output for instructing the servo press 72 to descend is issued. This step 1
08 is executed, the valve seat 38 is moved to the poppet valve 22.
Side, and the distance between the valve seat 38 and the poppet valve 22 is reduced. When the process of step 108 is completed, the process of step 104 is executed again. The processes in steps 104 to 108 are repeatedly executed until it is determined in step 106 that the flow rate of the air discharged from the fluid discharge passage 58 is equal to or less than the target flow rate. As a result, when it is determined that the air flow rate is equal to or less than the target flow rate, it can be determined that the interval between the valve seat 38 and the poppet valve 22 has reached an appropriate value. In this case, the process of step 110 is executed next.

In step 110, an output for instructing the servo press 72 to stop and ascend is issued. When the process of step 110 is performed, the pressing force applied to the valve seat 36 is released. The press-fit depth of the valve seat 36 is determined by executing step 110. In step 112, a process for closing the on-off valve 64 is executed. When the process of step 112 is performed, the supply of the high-pressure air to the fluid supply passage 56 is stopped.

[0041] At step 114, the output is generated to command the output stop of the current I ₀ to the power supply circuit 48. When the process of step 114 is performed, the electromagnetic coil 46
Is stopped. This step 11
When the process of No. 4 is completed, a series of processes necessary for press-fitting the valve seat 36 is completed. FIG. 5 shows a change occurring in the exciting current (FIG. 5 (A)), a change occurring in the air flow rate (FIG. 5 (B)), and a change occurring in the press-fitting position of the valve seat 36 (FIG. 5 (A)) in the series of processes described above. FIG. 5 (C) is shown.

The time chart shown in FIG.₀To
Step 100 (current I ₀Supply) run
Time t₁The processing in step 102 (opening / closing valve 64)
At the time t_Two~ T_ThreeThe above steps
Steps 104 to 108 (press fitting of valve seat 38) are repeated
Executed and at time t_ThreeThe above steps 112, 1
Process 14 (closing the on-off valve 64 and stopping the excitation current)
Is executed.

As shown in FIG. 5, according to the above-described processing, the press-fitting of the valve seat 36 can be stopped when the air flow rate discharged from the fluid discharge passage 58 matches the target value. When the press-fitting of the valve seat 36 is stopped at the above timing, the position of the valve seat 36 is adjusted to a position where desired characteristics can be realized in the poppet type electromagnetic proportional valve 10. Therefore, according to the above-described manufacturing method, it is possible to suppress variations in the characteristics of the poppet type electromagnetic proportional valve 10 and obtain stable quality.

In the above embodiment, the object 4 to be processed is
The step of setting the press-fitting device 4 in the press-fitting device 42 corresponds to the “first process” of the first embodiment.
By executing the processing of step 100, the “second step” of claim 1
The “third step” according to claim 1 is performed by executing the processing of step 2, and the “fourth step” according to claim 4 is performed by executing the processing of steps 104 to 110.
Have been realized respectively.

[0045]

As described above, according to the present invention, the position of the valve seat of the poppet type electromagnetic proportional valve can be adjusted to an appropriate position. Therefore, according to the present invention, it is possible to appropriately suppress the variation in the characteristics of the poppet type electromagnetic proportional valve.

[Brief description of the drawings]

FIG. 1 is a sectional view of a poppet type electromagnetic proportional valve.

FIG. 2 is a view for explaining characteristics of the poppet type electromagnetic proportional valve shown in FIG. 1;

FIG. 3 is a cross-sectional view of a press-fitting device used in an assembling method according to an embodiment of the present invention and a processing target processed by the press-fitting device.

FIG. 4 is a flowchart illustrating a series of processes performed by an assembling method according to an embodiment of the present invention.

FIG. 5 is a time chart showing changes accompanying a series of processes shown in FIG. 4;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Poppet-type electromagnetic proportional valve 12 Sleeve 14 and 46 Electromagnetic coil 20 Plunger 22 Poppet valve 24 Yoke 26 Spring 28 Convex part 30 Recess 32 Core 36 Valve seat 48 Power supply circuit 50 Sequencer 64 Open / close valve 72 Servo press

Claims (1)

[Claims] 1. A method for assembling a poppet-type electromagnetic proportional valve, comprising: a poppet valve that is displaced by a balance between an electromagnetic force and an urging force, wherein the poppet valve is displaced to continuously change a conduction state of a flow path. A first step of setting an electromagnetic coil for applying an electromagnetic force to the poppet valve at a predetermined position; a second step of flowing a predetermined exciting current through the electromagnetic coil; A third step of supplying a fluid having a predetermined pressure, the poppet valve and a valve seat of the poppet valve such that a flow rate of the fluid flowing through the flow path has a value corresponding to the exciting current and the predetermined pressure. And a fourth step of adjusting the positional relationship between the solenoid valve and the poppet-type electromagnetic proportional valve.