Solenoid valve

A solenoid valve is disclosed. The solenoid valve comprises: a fixed member having a tube portion; a mobile plunger positioned in the tube portion, the mobile plunger being axially movable between a first position and a second position; a rod coupled to the mobile plunger and having a spool for control of fluid flow, the rod being axially movable in the tube portion; an electromagnetic coil positioned externally to the fixed member; and an air gap positioned in the tube portion between the electromagnetic coil and the mobile plunger, wherein the air gap is formed in an internal surface of the tube portion.

TECHNICAL FIELD

This disclosure relates generally to the field of electromagnetically controlled valves, and particularly to the field of solenoid valves.

BACKGROUND

Valves are used in a variety of technical applications for controlling the flow of a fluid. Electromagnetically controlled valves have an electromagnet and by means of the electromagnet, the valve can be opened and closed.

WO0250462 discloses an electromagnetically-actuated two-way two-position valve that is normally closed. The valve comprises an axially-mobile group which has an upper end that faces a fixed group. An obturator is intercepted and then drawn in an opening movement by the mobile group. A return spring displaces the obturator towards a closed position when the fixed group is deactivated. An air gap is comprised, in a radial direction, between a coil for activating the fixed group and the upper end of the mobile group.

The present disclosure is directed, at least in part, to improving or overcoming one or more aspects of the prior art system.

BRIEF SUMMARY OF THE INVENTION

The present disclosure describes a solenoid valve. The solenoid valve comprises a fixed member having a tube portion; a mobile plunger positioned in the tube portion, the mobile plunger being axially movable between a first and a second position; a rod coupled to the mobile plunger and having a spool for control of fluid flow, the rod being axially movable in the tube portion; an electromagnetic coil positioned externally to the fixed member; and an air gap positioned in tube portion between the electromagnetic coil and the mobile plunger, characterized in that the air gap is formed in an internal surface of the tube portion.

DETAILED DESCRIPTION

This disclosure generally relates to a solenoid valve for control of fluid flow. The solenoid valve is configured to concentrate magnetic flux for actuation of the spool.FIG. 1illustrates a cross-section of the solenoid valve10. Solenoid valve10is an electromagnetically actuated valve. The solenoid valve10comprises a fixed member12, a mobile plunger14, a rod16having a spool18, an electromagnetic coil20and an air gap22.FIGS. 1-4illustrate a non-limiting first embodiment of the solenoid valve10in a three position, two way proportional pressure reducing valve.

Fixed member12comprises a tube portion24. Tube portion24is hollow with a lateral wall26surrounding bore28. The lateral wall26has an internal surface32and an external surface34. Tube portion24has an opening30. Bore28is delimited by the internal surface32and a base surface33. The tube portion24is axially elongated. In an embodiment, the tube portion24may be cylindrical. Tube portion24is made from ferromagnetic material. In an embodiment, the tube portion24is at least partially made from ferromagnetic material.

The solenoid valve10may further comprise a valve body36. The valve body36is mounted to the fixed member12. The valve body36is mounted to the tube portion24. Valve body36is mounted to the opening30of the tube portion24. Valve body36has a central channel38. Channel38has an aperture40. Channel38communicates with the bore28through the aperture40. Aperture40is formed on a first valve body end48. First valve body end48is positioned in the tube portion24. The valve body36has a second valve body end50formed opposite the first valve body end48. Second valve body end50is positioned external to the tube portion24.

Valve body36has a plurality of fluid ports52. Fluid ports52are positioned external to the fixed member12. Fluid ports52are spaced from the opening30. Fluid ports52mutually communicate through the central channel38. Second valve body end50is configured to carry at least one fluid port52. Further, fluid ports52may be positioned on the lateral surface of the valve body36.

In an embodiment, valve body36may be inserted into the bore28. A portion of the valve body36extends from the opening30into the bore28. In a further embodiment, the valve body36may be made from ferromagnetic material. Valve body36may serve to attract the mobile plunger14when the electromagnetic coil20is activated.

In an alternate embodiment, valve body36may be positioned at the opening30. The valve body36does not extend from the opening30into the bore28. In yet a further embodiment, the valve body36may be made from ferromagnetic material.

In an embodiment, the fixed member12further comprises a plunger portion (not shown). Plunger portion is located at an end opposite to the opening30. The plunger portion axially extends from the tube portion24. Plunger portion axially extends away from the opening30. Plunger portion and tube portion24may be monolithically formed. In yet a further embodiment, the plunger portion may be made from ferromagnetic material.

In an embodiment, the solenoid valve10may further comprise a fixed plunger (not shown). The fixed plunger is positioned in the tube portion24. Fixed plunger is positioned in the bore28. Fixed plunger may be fixedly positioned against the inner surface32of the tube portion24. In yet a further embodiment, the fixed plunger may be made from ferromagnetic material.

The mobile plunger14is positioned in the fixed member12. Mobile plunger14is positioned in the tube portion24. Mobile plunger14is axially movable in the tube portion24. Mobile plunger14is axially movable in the bore28. Mobile plunger14is configured to slidably move in the tube portion24. Mobile plunger14may have a first end42, a second end44and a contact surface46. Contact surface46is bordered by the first and second ends42,44at opposite sides. Contact surface46is in slidable contact with the internal surface32of the lateral wall26of the tube portion24. First end42may abut the base surface33of the bore28. Second end44may abut the first valve body end48of the valve body36.

With respect to referenceFIG. 1, the second end44is configured to have a coupling element56for coupling to rod16. Coupling element56comprises a hole58. Hole58is centrally positioned at the second end44. The mobile plunger14is axially movable between a first and a second position. The mobile plunger14may move towards the base surface33to the first position. The mobile plunger14may move in a first direction of travel. The mobile plunger14may move towards the valve body36to the second position. The mobile plunger14may move in a second direction of travel. First and second positions are the extreme points of travel of the mobile plunger14. In an embodiment, the limits of travel of the mobile plunger14may be determined by magnetic forces. The mobile plunger14may be adjacent the base surface33at the first position. The mobile plunger14may be adjacent the valve body36at the second position. In an alternate embodiment, the limits of travel of the mobile plunger14may be determined by the structures in the bore28. In a further embodiment, mobile plunger14may abut the base surface33at a first end of travel that defines the first position. Mobile plunger14may abut the valve body36at a second end of travel that defines the second position. In an alternate further embodiment, mobile plunger14may abut a fixed plunger at a second end of travel that defines the second position.

The solenoid valve10further comprises an elastic member54. Elastic member54is provided to return the mobile plunger14from an electromagnetically actuated position. In an embodiment, the elastic member54may be compressed when the mobile plunger14is at an electromagnetically actuated position. In an embodiment, the elastic member54may be extended when the mobile plunger14is at an electromagnetically actuated position. The elastic member54may be positioned between the mobile plunger14and the valve body36.

With reference toFIG. 1, the rod16is coupled to the mobile plunger14. Rod16is axially elongated. The rod16is axially movable in the tube portion24. Rod16is supported by the mobile plunger14in the bore28. Rod16extends into the channel38of the valve body36through aperture40. Rod16is axially movable in the channel38.

Rod16has a coupling end64. Coupling end64comprises a head66and a collar68. Head66is positioned at the terminal point of the rod66. The head66is connected to a stem70though the collar68. Collar68has a reduced diameter with respect to the head66and the stem70. Head66has a ledge72extending over the collar68. Coupling end64couples to the coupling element56of the mobile plunger14. The head66fits into the hole58. Rod16moves correspondingly with the mobile plunger14between the first and second position. The rod16may move along the first or the second directions of travel with the mobile plunger14.

The spool18is positioned at an opposite end of the rod16relative to the coupling end64. In an embodiment, spool18is integrated into the rod16. In an alternate embodiment, spool18is coupled to the rod16. The spool18spool extends into the valve body36. Spool18controls fluid flow through the fluid ports52in the valve body36. Spool18moves correspondingly with the mobile plunger14. The spool18is positionable to control fluid flow through the valve body36as the mobile plunger14moves between the first and second position. Spool18comprises fluid ports86and a conduit88for flow of fluid.

The electromagnetic coil20is positioned externally to the fixed member12. Electromagnetic coil20is positioned relative to the mobile plunger14so as to effect actuation thereof upon activation. In an embodiment, electromagnetic coil20is positioned in axial correspondence to the valve body36so as to effect actuation the mobile plunger14at activation.

Electromagnetic coil20is positioned to axially correspond to the valve body36. Electromagnetic coil20is positioned to partially overlap the valve body36. Electromagnetic coil20is positioned to axially correspond to the mobile plunger14. Electromagnetic coil20is positioned to partially overlap the mobile plunger14. Electromagnetic coil20is positioned to axially correspond to the mobile plunger14at the second end44. Electromagnetic coil20is positioned to partially overlap the second end44of the mobile plunger14. Electromagnetic coil20is positioned to axially correspond to the air gap22. Electromagnetic coil20is positioned to overlap air gap22.

The air gap22is positioned in tube portion24. The air gap22, in the tube portion22, is positioned between the electromagnetic coil20and the mobile plunger14. The air gap22is axially located along the tube portion24so as to be positioned between the electromagnetic coil20and the mobile plunger14. The air gap22is positioned between the electromagnetic coil20and the mobile plunger14in the radial direction relative to a longitudinal axis A of the tube portion24. In an embodiment, the air gap22is positioned remote from the base surface33of the bore28. The air gap22is spaced from the valve body36.

With reference toFIG. 2, the air gap22is formed in the internal surface32of the tube portion24. Air gap22extends radially from the internal surface32into the lateral wall26of the tube portion24. Air gap22surrounds the bore28. Air gap22has a slot74. Air gap22opens to the bore28through the slot74. Slot74faces the mobile plunger14. Slot74extends around the inner surface32. In an embodiment, the air gap22is annular. Air gap22is formed as an annular channel that encircles the bore28. Slot74is formed as an annular opening.

In an embodiment, the air gap22is positioned adjacent the first end42of the mobile plunger14. The air gap22is positioned adjacent the first end42of the mobile plunger14in a radial direction relative to a longitudinal axis A of the tube portion24. The air gap22encircles the first end42. In an alternative embodiment, the air gap22is positioned adjacent the second end44of the mobile plunger14. The air gap22is positioned adjacent the second end44of the mobile plunger14in a radial direction relative to a longitudinal axis A of the tube portion24. The air gap22encircles the second end44. The air gap22overlaps the second end42. In yet a further embodiment, the solenoid valve10may have a first and a second air gap22. The first air gap22is positioned adjacent the first end42of the mobile plunger14. The second air gap22is positioned adjacent the second end44of the mobile plunger14.

The air gap22has an axially extending bottom surface76. The air gap22, formed as an annular channel, has an axially extending bottom surface76. The bottom surface76extends in the same direction as the lateral wall26. Bottom surface76forms an annular surface of the air channel. Bottom surface76is concentric with the external surface34of the lateral wall26. Bottom surface76is concentric with the slot74.

The air gap22has a linear side78. The air gap22, formed as an annular channel, has a linear side78. Linear side78extends from the bottom surface76. Linear side78extends to the internal surface32. Linear side78delimits one side of the slot74. The linear side78is substantially perpendicular to the bottom surface76. Linear side78may be substantially perpendicular to the longitudinal axis A of the tube portion24. Linear side78forms an annular lateral surface of the air channel. Linear side78extends radially from the internal surface32into the lateral wall26of the tube portion24. In an embodiment, the linear side78is proximate to the mobile plunger14at the first position. The concentration of the magnetic flux increases with the increasing depth of the air gap22. The depth of the air gap22may correspond to the length of the linear side78.

The air gap22has an inclined side80. The air gap22, formed as an annular channel, has an inclined side80. Inclined side80is opposite the linear side78. Inclined side80inclines towards the linear side78. Inclined side80inclines into the annular channel. Inclined side80extends from the bottom surface76. Inclined side80extends to the internal surface32. Inclined side80delimits the opposite side of the slot74. The width of the slot74is determined by the distance between the linear side78and the inclined side80. The width of the air gap22increases with the depth thereof. The transverse distance between the linear side78and the inclined side80increases with the increase in distance from the slot74to the bottom surface76. In an embodiment, the inclined side88is distal from the mobile plunger14at the first position. The inclined side88is distal from the second end44of the mobile plunger14at the first position.

The inclined side80is substantially inclined relative to the internal surface32of the lateral wall26. The inclined surface80and internal surface32have an angle α therebetween. The angle α has a range of 45 to 60 degrees. Inclined side80may be substantially inclined relative to the longitudinal axis A of the tube portion24. Inclined side80forms an annular inclined lateral surface of the air channel. The inclined side80is substantially inclined relative to the bottom surface76.

An apex84is positioned in the air gap22. The apex84is positioned in the annular channel. The apex84is formed between the inclined side80and the internal surface32of the tube portion24. Apex84is positioned between the bottom surface76and the bore28. Apex84is positioned between the bottom surface76and the bore28in the radial direction relative to the longitudinal axis A of the tube portion24. Apex84is positioned between the bottom surface76and the mobile plunger14. Apex84is positioned between the bottom surface76and the mobile plunger14in the radial direction relative to the longitudinal axis A of the tube portion24. Magnetic flux is concentrates in the apex84.

In operation the movement of the mobile plunger14between the first and second position opens and closes the air gap22. The mobile plunger14moves relative to the air gap22. The contact surface46moves to close or open the slot74. As the mobile plunger14moves from the first position to the second position the second end44may move towards the apex84thereby closing the slot74. As the length of slot74is reduced, relative distance between the second end44and the apex84, the magnetic flux increases until the slot74is closed when the second end44is level with the apex84. The valve10starts to open so as to enable fluid flow. The mobile plunger14may move further so that the second end44moves beyond the apex84.

As the mobile plunger14moves from the second position to the first position the second end44may move away from the apex84. The valve10starts to close when the second end44moves from being level with the apex84towards the linear side78.

FIG. 1illustrates the solenoid valve10in the deactivated configuration. The electromagnetic coil20is not activated so as to effect a movement of the mobile plunger14to the second position. The mobile plunger14remains in the first position. The elastic member54, positioned between the mobile plunger14and the valve body36, is not compressed.

The spool18is positioned in the valve body36so that second valve body fluid ports52bare not in communication with first spool fluid ports86a. The first valve body fluid ports52aare not in communication with the first spool fluid ports86a. No fluid flows through the solenoid valve10.

FIG. 3illustrates the solenoid valve10in operation and in a first active configuration. The electromagnetic coil20is activated so as to effect a movement of the mobile plunger14to the second position. The mobile plunger14moves towards the valve body36. Mobile plunger14is actuated to the apex84of the air gap22. The elastic member54, positioned between the mobile plunger14and the valve body36, is compressed.

The rod16and the spool18are correspondingly moved. The spool18is positioned in the valve body36so that first valve body fluid ports52aare positioned to communicate with first spool fluid ports86a. The path of the fluid flow is indicated by an arrow. Fluid flows through the first valve body fluid ports52ainto the first spool fluid ports86a. Fluid flows into the conduit88and out through the second spool fluid port86b. Fluid flows into the channel38and out through the third valve body fluid port52c.

The strength of the magnetic force is proportional to the amount of current with which is supplied to the electromagnetic coil. When the solenoid valve10is actuated, pressurised fluid flows through first valve body fluid ports52ato first spool fluid ports86aand into the conduit88. The magnetic force is opposed by the fluid pressure acting on the spool18in the conduit88. The solenoid valve10finds an equilibrium when the magnetic force is equal to the force generated by the fluid pressure flowing through the first spool fluid ports86a.

When the electromagnetic coil20is deactivated, the mobile plunger14is no longer attracted to the valve body36. The elastic member54pushes the mobile plunger14away from the valve body36. The rod16and the spool18are correspondingly moved. The spool18is positioned in the valve body36so that the first valve body fluid ports52ais not in communication with the first spool fluid ports86a.

FIG. 4illustrates the solenoid valve10in operation and in a second active configuration. If the flow rate of the pressurized fluid from first valve body fluid ports52ato first spool fluid ports86aincreases the pressure in conduit88increases correspondingly and the force generated increases correspondingly. If the force in the conduit88exceeds the magnetic force, the mobile plunger14moves accordingly. The mobile plunger14moves towards the first position. The mobile plunger14moves partially away from the valve body36.

The spool18is positioned in the valve body36so that second valve body fluid ports52bare positioned to be in communication with first spool fluid ports86a. The first valve body fluid ports52aare not in communication with the first spool fluid ports86a.

The path of the pressurized fluid flow is indicated by an arrow. of the pressurized fluid flows into the channel38through the third valve body fluid port52c. The pressurized fluid flows into the conduit88through second spool fluid port86band to the first spool fluid ports86a. The pressurized fluid flow exits the valve body36through second valve body fluid ports52bfrom the first spool fluid ports86a.

The solenoid valve10moves between the first and second configuration until the force generated by the pressurized fluid flow is balanced with magnetic force.

FIG. 5illustrates a second embodiment of the solenoid valve10. The specific features with respect to the second embodiment will now be described. Valve body36is not illustrated. A fixed plunger92is positioned in the tube portion24. Fixed plunger92is positioned in the bore28. Fixed plunger92is positioned between the mobile plunger14and the opening30of the tube member24. Fixed plunger92may be fixedly positioned against the inner surface32of the tube portion24. Fixed plunger92has a through hole94. Rod16extends from the mobile plunger14through the through hole94. Rod16is axially movable in the through hole94.

The second end44of the mobile plunger14faces the fixed plunger92. The air gap22is positioned adjacent the fixed plunger92. Air gap22is positioned adjacent the second end44of the mobile plunger14. The air gap22overlaps the second end44of the mobile plunger14. The linear side78is proximate to the mobile plunger14at the first position. The inclined side80is distal from the mobile plunger14at the first position. The inclined side80is distal from the second end44of the mobile plunger14at the first position.

Electromagnetic coil20is positioned to axially correspond to the fixed plunger92. Electromagnetic coil20is positioned to partially overlap fixed plunger92. Electromagnetic coil20is positioned to axially correspond to the mobile plunger14. Electromagnetic coil20is positioned to partially overlap the mobile plunger14. Electromagnetic coil20is positioned to axially correspond to the mobile plunger14at the second end44. Electromagnetic coil20is positioned to partially overlap the second end44of the mobile plunger14. Electromagnetic coil20is positioned to axially correspond to the air gap22. Electromagnetic coil20is positioned to overlap air gap22. At the activation of the electromagnetic coil20the mobile plunger14is actuated to move from the first position towards the fixed plunger92. The mobile plunger14may abut the fixed plunger92at the second position.

FIG. 6illustrates a third embodiment of the solenoid valve10. The specific features with respect to the third embodiment will now be described. Valve body36and the rod16are not illustrated. Fixed member12comprises the tube portion24and a plunger portion90. Plunger portion90is located at an end opposite to the opening30. The plunger portion90axially extends from the tube portion24. Plunger portion90axially extends away from the opening30. Plunger portion90and tube portion24may be monolithically formed.

The first end42of the mobile plunger14faces the plunger portion90. The base surface33of the bore28is formed by the plunger90. The air gap22is positioned adjacent the plunger portion90. Air gap22is positioned adjacent the first end42of the mobile plunger14. The air gap22overlaps the first end42of the mobile plunger14. The linear side78is proximate to the mobile plunger14at the first position. The inclined side88is distal from the mobile plunger14at the first position. The inclined side88is distal from the first end42of the mobile plunger14at the first position.

Electromagnetic coil20is positioned to axially correspond to the plunger portion90. Electromagnetic coil20is positioned to partially overlap plunger portion90. Electromagnetic coil20is positioned to axially correspond to the mobile plunger14. Electromagnetic coil20is positioned to axially correspond to the first end42mobile plunger14. Electromagnetic coil20is positioned to partially overlap mobile plunger14. Electromagnetic coil20is positioned to partially overlap the mobile plunger14at the first end42. Electromagnetic coil20is positioned to axially correspond to the air gap22. Electromagnetic coil20is positioned to overlap air gap22. At the activation of the electromagnetic coil20the mobile plunger14is actuated to move from the first position towards the plunger portion90. The mobile plunger14may abut the plunger portion90at the second position.

FIG. 7illustrates a fourth embodiment of the solenoid valve10. The specific features with respect to the fourth embodiment will now be described. Valve body36is not illustrated. Fixed member12comprises the tube portion24and a plunger portion90. Plunger portion90is located at an end opposite to the opening30. The plunger portion90axially extends from the tube portion24. Plunger portion90axially extends away from the opening30. Plunger portion90and tube portion24may be monolithically formed.

The first end42of the mobile plunger14faces the plunger portion90. The base surface33of the bore28is formed by the plunger90. A first air gap22is positioned adjacent the plunger portion90. The first air gap22is positioned adjacent the first end42of the mobile plunger14. The first air gap22overlaps the first end42of the mobile plunger14. The linear side78is proximate to the mobile plunger14at the first position. The inclined side88is distal from the mobile plunger14at the first position. The inclined side88is distal from the first end42of the mobile plunger14at the first position. The first position is the neutral position of the mobile plunger14. The second position of the mobile plunger14may be a first actuated position or a second actuated position.

A first electromagnetic coil20is positioned to axially correspond to the plunger portion90. The first electromagnetic coil20is positioned to partially overlap plunger portion90. The first electromagnetic coil20is positioned to axially correspond to the mobile plunger14. The first electromagnetic coil20is positioned to axially correspond to the first end42of the mobile plunger14. The first electromagnetic coil20is positioned to partially overlap mobile plunger14. The first electromagnetic coil20is positioned to partially overlap the mobile plunger14at the first end42. The first electromagnetic coil20is positioned to axially correspond to the first air gap22. The first electromagnetic coil20is positioned to overlap the first air gap22. At the activation of the first electromagnetic coil20the mobile plunger14is actuated from the first position to move towards the plunger portion90at a first actuated position. The mobile plunger14may abut the plunger portion90at the first actuated position. In an embodiment, the mobile plunger14may be actuated from the second actuated position to move towards the plunger portion90at the first actuated position.

A fixed plunger92is positioned in the tube portion24. Fixed plunger92is positioned in the bore28. Fixed plunger92may be fixedly positioned against the inner surface32of the tube portion24. Fixed plunger92is positioned between the mobile plunger30and the opening30of the tube member24. Fixed plunger92has a though hole94. Rod16extends from the mobile plunger14through the through hole94. Rod16is axially movable in the through hole94. Rod16is coupled to the mobile plunger14through a pin17. The pin17traverses through the mobile plunger14and the rod16. Rod16is accommodated in the bore28of the mobile plunger14.

A second air gap22is positioned in the tube portion24between a second electromagnetic coil20and the mobile plunger14. The second air gap22is formed in the internal surface32of the tube portion24. The second end44of the mobile plunger14faces the fixed plunger92. The second air gap22is positioned adjacent the fixed plunger portion92. The second air gap22is positioned adjacent the second end44of the mobile plunger14. The second air gap22overlaps the second end44of the mobile plunger14. The linear side78is proximate to the mobile plunger14at the first position. The linear side78is proximate to the second end44of the mobile plunger14at the first position. The inclined side88is distal from the mobile plunger14. The inclined side88is distal from the second end44of the mobile plunger14.

The second electromagnetic coil20is positioned externally to the fixed member12. The second electromagnetic coil20may be positioned adjacent the first electromagnetic coil20. The second electromagnetic coil20is positioned to axially correspond to the fixed plunger92. The second electromagnetic coil20is positioned to partially overlap fixed plunger92. The second electromagnetic coil20is positioned to axially correspond to the mobile plunger14. The second electromagnetic coil20is positioned to axially correspond to the second end44of the mobile plunger14. The second electromagnetic coil20is positioned to partially overlap mobile plunger14. The second electromagnetic coil20is positioned to partially overlap the mobile plunger14at the second end44. The second electromagnetic coil20is positioned to axially correspond to the second air gap22. The second electromagnetic coil20is positioned to overlap the second air gap22. At the activation of the second electromagnetic coil20the mobile plunger14is actuated to move from the first positioned towards the fixed plunger92at the second actuated position. The mobile plunger14may abut the fixed plunger92at the second actuated position. In an embodiment, the mobile plunger14may be actuated from the first actuated position to move towards the fixed portion92at the second actuated position.FIG. 12illustrates a fifth embodiment of the solenoid valve10. The specific features with respect to the fifth embodiment will now be described. Valve body36is not illustrated. Fixed member12comprises the tube portion24and a plunger portion90. Plunger portion90is located at an end opposite to the opening30. The plunger portion90axially extends from the tube portion24. Plunger portion90axially extends away from the opening30. Plunger portion90and tube portion24may be monolithically formed. Plunger portion90has a though hole96. Rod16extends from the plunger portion90through the through hole96. Rod16is axially movable in the through hole96.

A first end42of a first mobile plunger14faces the plunger portion90. The base surface33of the bore28is formed by the plunger portion90. A first air gap22is positioned adjacent the plunger portion90. The first air gap22is positioned adjacent the first end42of the mobile plunger14. The first air gap22overlaps the first end42of the mobile plunger14. The linear side78is proximate to the first mobile plunger14at the first position. The inclined side88is distal from the first mobile plunger14at the first position. The inclined side88is distal from the first end42of the first mobile plunger14at the first position. The first mobile plunger14has a through channel98. Rod16extends from the first mobile plunger14through the through hole98. Rod16is coupled to the second end44of the mobile plunger16. Rod16extends through the first end42of the mobile plunger14.

A first electromagnetic coil20is positioned to axially correspond to the plunger portion90. The first electromagnetic coil20is positioned to partially overlap plunger portion90. The first electromagnetic coil20is positioned to axially correspond to the first mobile plunger14. The first electromagnetic coil20is positioned to axially correspond to the first end42of the first mobile plunger14. The first electromagnetic coil20is positioned to partially overlap first mobile plunger14. The first electromagnetic coil20is positioned to partially overlap the first mobile plunger14at the first end42. The first electromagnetic coil20is positioned to axially correspond to the first air gap22. The first electromagnetic coil20is positioned to overlap the first air gap22. At the activation of the first electromagnetic coil20the first mobile plunger14is actuated to move from the first position towards the plunger portion90at the second position. The first mobile plunger14may abut the plunger portion90at the second position.

The solenoid valve10further comprises a second fixed member12having a second tube portion24. The second tube portion24is connected to the plunger portion90of the first tube portion24. The second tube portion24may be welded to the plunger portion90of the first tube portion24. A second mobile plunger14is positioned in the second tube portion24. The second mobile plunger14being axially movable between a first and a second position. The rod16is coupled to the second mobile plunger14wherein the rod16extends from the second mobile plunger14through the plunger portion90to the first mobile plunger14. A second electromagnetic coil20is positioned externally to the first and second fixed members12,12. A second air gap22is positioned in second tube portion24between the second electromagnetic coil20and the second mobile plunger14. The second air gap22is formed in an internal surface32of the second tube portion24.

The second end44of the second mobile plunger14faces the plunger portion90. The second air gap22is positioned adjacent the plunger portion90. The second air gap22overlaps the second end44. The second air gap22is positioned adjacent the second end44of the second mobile plunger14. The linear side78is proximate to the second mobile plunger14at the first position. The inclined side88is distal from the second mobile plunger14at the first position. The inclined side88is distal from the second end44of the second mobile plunger14at the first position.

The second electromagnetic coil20is positioned to axially correspond to the plunger portion90. The second electromagnetic coil20may be adjacent to the first electromagnetic coil. Electromagnetic coil20is positioned to partially overlap plunger portion90. Second electromagnetic coil20is positioned to axially correspond to the second mobile plunger14. Second electromagnetic coil20is positioned to axially correspond to the second end44of the second mobile plunger14. Second electromagnetic coil20is positioned to axially correspond to the second mobile plunger14. Second electromagnetic coil20is positioned to partially overlap the mobile plunger14at the second end44. Second electromagnetic coil20is positioned to axially correspond to the second air gap22. Second electromagnetic coil20is positioned to overlap second air gap22. At the activation of the second electromagnetic coil20the second mobile plunger14is actuated to move from the first position towards the plunger portion90. The second mobile plunger14may abut the plunger portion90at the second position.

The skilled person would appreciate that foregoing embodiments may be modified or combined to obtain the solenoid valve10of the present disclosure.

INDUSTRIAL APPLICABILITY

This disclosure describes a solenoid valve10having a concentration of the magnetic flux in the tube24at the air gap22. The magnetic flux is further concentrated at the apex84. The concentration of the magnetic flux increases with the increasing depth of the air gap22. The concentration of the magnetic flux in the air gap22and at the apex84enables flattening of the magnetic force curve when the linear position of the mobile plunger changes, so that in varying the stroke of the mobile plunger the magnetic force remains more constant. The portion of the solenoid valve10that concentrates magnetic flux is not made of non-magnetic material shown such as a bronze welding, but it consists of the air collected in the air gap22.

Where technical features mentioned in any claim are followed by reference signs, the reference signs have been included for the sole purpose of increasing the intelligibility of the claims and accordingly, neither the reference signs nor their absence have any limiting effect on the technical features as described above or on the scope of any claim elements.

One skilled in the art will realise the disclosure may be embodied in other specific forms without departing from the disclosure or essential characteristics thereof. The foregoing embodiments are therefore to be considered in all respects illustrative rather than limiting of the disclosure described herein. Scope of the invention is thus indicated by the appended claims, rather than the foregoing description, and all changes that come within the meaning and range of equivalence of the claims are therefore intended to be embraced therein.

The disclosures in European Patent Application No. 18425041.3 from which this application claims priority are incorporated herein by reference.