JP2006349142A - Low leakage poppet solenoid valve - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a solenoid control valve capable of minimizing leakage through a discharge port when the solenoid valve is under minimum pressure and maximum pressure. <P>SOLUTION: This double poppet low leakage variable bleed solenoid valve comprises a solenoid part having an adjustable end cap mounted through a solenoid. The discharge port is formed around the end cap. A hydraulic part has a valve housing connectable with the solenoid part. The hydraulic part has a control capacity formed in the part, and a supply port is connected through the valve housing. A valve shaft is slidable through the solenoid part, and longitudinally extends to the hydraulic part. A first end portion of the valve shaft is ended at the solenoid part forming a primary valve, and a second end portion of the valve shaft is ended at the hydraulic part forming a secondary valve. The valve shaft further has a hollow passage formed through the valve shaft to allow a fluid medium to pass between the first end portion and the second end portion of the valve shaft. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an electromagnetically actuated bleed hydraulic control valve that minimizes the amount of leakage through a discharge port when the solenoid valve is at a minimum pressure and a maximum pressure.

  Prior art solenoid valves are often used to control hydraulic fluid flow in transmission systems in automobiles. Conventional variable bleed solenoid valves regulate pressure by reducing the pressure in the control volume through a variable leak path (discharge port) to the pressure reservoir. The amount of leakage is inversely proportional to the pressure in the control part of the valve. This amount of leakage is typically controlled by a variable orifice that takes the form of a sealing member (flat, conical, ball-shaped, etc.) that moves relative to a stationary annular sealing surface surrounding the stationary orifice. When the sealing member comes into contact with the sealing surface, the leakage is close to zero and the pressure in the control volume reaches its maximum value. As the sealing member moves away from the sealing surface, the amount of leakage increases and the control volume pressure drops at a rate that is a function of the shortest distance wipe area between the sealing member and the seat. The amount of leakage can become significant as the number of solenoid devices arranged in the transmission increases. Minimizing the amount of leakage in each individual solenoid valve component is desirable to minimize the required capacity of the hydraulic pump that generates the system pressure and to improve the efficiency of the transmission. A variable bleed solenoid valve with a low leakage design minimizes this amount of leakage. By integrating the supply shutoff (secondary) valve in series with the discharge bleed (primary) valve, the amount of leakage to the reservoir can be minimized. These two valves are actuated simultaneously. When the discharge bleed (primary) valve is fully open to achieve the minimum control volume pressure, the supply shut-off (secondary) valve is fully closed to prevent fluid leakage to the reservoir through the control volume. When the discharge bleed (primary) valve is closed to increase the control volume pressure, the supply shutoff (secondary) valve opens to allow fluid to enter the control volume. At maximum control volume pressure, the discharge bleed (primary) valve is fully closed and the supply shutoff (secondary) valve is fully open.

  One disadvantage of the known low-leakage variable bleed solenoid valve is that the structure of the solenoid valve is complicated as a result of the addition of a supply shutoff valve adjacent to the discharge bleed valve. Additional components for changing the direction of flow often have complex geometries that are difficult to manufacture and costly. Another disadvantage is that many of the known low-leakage variable bleed valves are susceptible to fluctuations in supply pressure and temperature because they have a hydraulic region that is subject to unbalanced supply pressure. The invention described herein differs from the prior art by utilizing a simpler valve and flow geometry that also has the advantage of minimizing the feedback area of the supply pressure.

  The present invention relates to a new and improved low leakage poppet solenoid valve for use in automotive transmission systems. The valve has a solenoid portion (eg, a magnet portion) having a housing that encloses a coiled bobbin. An adjustable end cap is disposed through the housing and has an exhaust port disposed about the end cap. The hydraulic part has a valve housing connectable to the solenoid part. The hydraulic portion has a control volume formed therein and a supply port is connected through the valve housing. A valve stem assembly comprising a valve stem and an annular armature mounted therearound is slidably disposed through the solenoid portion so that the bobbin is disposed annularly around the armature. The hydraulic portion extends through the solenoid portion via the valve shaft to complete the hydraulic portion. The valve stem has a first end that terminates in an adjacent solenoid portion and has a poppet formed about the first end. The second end of the valve stem is disposed adjacent to the hydraulic portion and has a second poppet formed around the second end. The valve stem further includes a hollow passage disposed through the valve stem to allow fluid medium to pass between the first end and the second end of the valve stem.

  The primary valve seat is formed as part of the end cap and is housed within the solenoid portion. The primary valve is the main control valve during most of the pressure range. The primary valve seat is configured to be positioned adjacent to the primary poppet of the valve stem. The secondary valve seat is housed in the hydraulic portion and is positioned adjacent to the secondary poppet of the valve stem. The secondary valve seat is arranged between the control volume and the supply port of the hydraulic part. In addition, the secondary valve seat has an opening extending therethrough to allow interaction between the supply port and the control volume. The secondary poppet controls the secondary control valve within a low pressure range.

  The pole piece is annularly disposed in the solenoid portion adjacent to the bobbin. The pole piece has a reduced diameter inner flange. The armature is attached to the valve stem and is configured to align with and slidably circumscribe the flange with the reduced inner diameter of the pole piece. The armature is surrounded by a bobbin and a coil so that the valve stem can slide longitudinally in response to excitation of the solenoid portion. In one embodiment, the spring element is formed around the valve shaft and when the solenoid is deactivated by extending between the armature and the upper bearing, the valve shaft is driven by the secondary poppet by the spring element. Slide in a direction that comes into contact with the secondary valve seat.

  Further areas of applicability of the present invention will become apparent from the detailed description provided hereinafter. It should be understood that the detailed description and specific examples, while indicating the preferred embodiment of the invention, are intended for purposes of illustration only and are not intended to limit the scope of the invention.

The present invention will become more fully understood from the detailed description and the accompanying drawings, wherein:
The following description of the preferred embodiment is merely an example in nature and is not intended to limit the invention, its application, or uses in any way.

  FIG. 1 is a longitudinal sectional plan view of a double poppet low leakage variable bleed solenoid valve 10. The valve 10 includes a solenoid portion 24 b having a housing 14 that encloses the bobbin 16, which has a coil 18 wound around the bobbin 16. When the coil 18 is excited, a magnetic field is generated in the solenoid portion 12. The solenoid portion 12 also has an end cap 20 that has an exhaust port 22 disposed about the end cap 20.

  The valve 10 also includes a hydraulic portion 24a having a valve housing 26 that can be connected to the solenoid portion 24b. More specifically, the portion of the flux tube 28 of the valve housing 26 slides into the solenoid portion 24 b adjacent to the bobbin 16. The hydraulic portion 24a also has a control volume 30 disposed at one end of the valve housing 26 opposite the solenoid portion 24b. The supply port 32 is connected via the valve housing 26 at a position disposed above the control volume 30. In this embodiment, the valve housing 26 mates with the outer bore, and the O-ring seal 33 separates the supply pressure region outside the valve housing 26 from the control volume 30. The second O-ring seal 35 isolates the supply pressure region outside the valve housing 26 from the ambient pressure or reservoir pressure region. It will be readily appreciated that other fittings can be used to secure the valve body within the manifold. Alternatively, the valve body may be formed as part of the manifold.

  The valve shaft 34 is slidably disposed through the solenoid portion 24b and extends longitudinally into the hydraulic portion 24a. The valve shaft 34 has a hollow passage 36 that extends through the longitudinal axis of the valve shaft 34. The hollow passage 36 allows the fluid medium to flow from the hydraulic portion 24a to the solenoid portion 24b. Further, the hollow passage 36 can serve the purpose of dampening the movement of the valve shaft 34 and thereby improving the stability of the solenoid valve 10.

  The hollow passage 36 has a first end that terminates in a primary valve 38 disposed within the solenoid portion 24b. The primary valve 38 is formed by a primary poppet 40 formed around the end of the valve shaft 34 and a primary valve seat 42 formed on the end cap 20. The primary poppet 40 and the primary valve seat 42 together form a primary valve 38 that opens and closes as the valve shaft 34 slides along its longitudinal axis.

  The hollow passage 36 has a second end that terminates at a secondary valve 44 disposed in the hydraulic portion 24a. The secondary valve 44 is formed by a secondary poppet 46 that is an end of the valve shaft 34. The secondary poppet 46 is configured to be slidably seated on a secondary valve seat 48 having an opening 50 extending through the secondary valve seat 48 to the control volume 30. The secondary poppet 46 and the secondary valve seat 48 together form a secondary valve 44 that is controlled by the movement of the valve stem 34.

  An alternative embodiment of the secondary valve 44 is shown in FIGS. 1a, 1b and 1c. In FIG. 1 a, the secondary valve 44 does not have a secondary poppet 46. Instead, the end of the valve shaft 34 contacts the secondary valve seat 48 and abuts against the secondary valve seat 48 to close the secondary valve 44.

  FIG. 1 b shows another alternative embodiment of the secondary valve 44 with a nozzle 47 from which the secondary valve seat 48 projects. The valve shaft 34 is aligned with the protruding nozzle 47, so that the end of the valve shaft 34 slides over the protruding nozzle 47 and circumscribes the protruding nozzle 47. This configuration is useful in applications that require a tighter seal to prevent undesirable leakage of the secondary valve 44.

  In FIG. 1 c, one alternative embodiment of the secondary valve 44 is shown in which the secondary valve seat 48 has a tapered surface 49. The end of the valve shaft 34 has a ring 51 that circumscribes the flanged overhanging portion of the end of the valve shaft 34 and forms the flanged overhanging portion. The ring 51 contacts the tapered surface 49 of the secondary valve seat 48. The ring 51 serves to provide a tighter seal to prevent undesirable leakage of the secondary valve 44.

  It is also within the scope of the present invention to incorporate the alternative embodiment shown in FIGS. 1a, 1b and 1c, in which the primary valve 38 is disposed within the solenoid portion 24b. The primary valve 38 does not have the primary poppet 40 and can be configured such that the end of the valve shaft 34 closes the primary valve 38 by contacting the primary valve seat 42. This form is similar to the embodiment shown in FIG.

  The primary valve seat 42 has a protruding nozzle and the end of the valve stem 34 slides over the protruding nozzle in a manner similar to the alternative embodiment of the secondary valve 44 shown in FIG. 1b. In addition, it is within the scope of the present invention to be in the form of the primary valve 38 that circumscribes the protruding nozzle.

  Finally, the primary valve seat 42 has a tapered surface such that the end of the valve shaft 34 circumscribes the flanged overhang at the end of the valve shaft 34 and has a ring that forms the flanged overhang. It is also within the scope of the present invention that the primary valve 38 is used. The ring contacts the tapered surface of the valve seat 42 and forms a tight seal. This embodiment of the primary valve 38 operates in a manner similar to the ring 51 at the tapered surface 49 shown in FIG. 1c.

  In operation, the double poppet low leakage valve 10 functions in response to excitation of the solenoid portion 12. When the coil 18 is energized, the valve stem 34 slides in a first direction along its longitudinal axis. In order to facilitate the movement of the valve shaft 34, the armature 52 is annularly arranged around the valve shaft 34 and is fixed to the valve shaft 34 by pressure fitting or the like, or is bonded, soldered or welded to the valve shaft 34. May be. The armature 52 is affected by the magnetic flux generated as a result of excitation of the coil 18. This produces a linear movement of the valve stem 34 that is proportional to the amount of current flowing through the coil 18 within the solenoid portion 12. When the solenoid portion 12 is energized, the valve stem 34 slides in the first direction toward the end cap 20 so that the primary poppet 40 is seated against the primary valve seat 42, thereby causing the primary valve. 38 is closed. At the same time, the secondary poppet 46 moves away from the secondary valve seat 48 due to the movement of the valve shaft 34, so the secondary valve 44 opens.

  In this embodiment of the invention, when the coil 18 of the solenoid portion 12 is released from the excited state, the spring 60 causes the armature 52 to point in a second direction opposite to the direction in which the armature 52 moves when excited. Slide. The spring 60 in this embodiment of the present invention is disposed between the armature 52 and the upper bearing 64. When the solenoid portion 12 is released from the excited state, the spring 60 exerts a force on the armature 52 and moves the valve stem 34 in the opposite direction to bring the secondary poppet 46 into contact with the secondary valve seat 48. The valve 44 is closed. At the same time, when the primary poppet 40 leaves the primary valve seat 42, the primary valve 38 moves to a fully open position. In order to facilitate the movement of the valve shaft 34, a lower bearing 62 is disposed between the wall of the valve housing 26 and the valve shaft 34, and an upper bearing 64 is disposed between the valve shaft 34 and the pole piece 54. This allows the valve stem 34 to slide more freely along its longitudinal axis.

  To achieve the desired proportional magnetic flux, a pole piece 54 is disposed within the solenoid portion 12 disposed adjacent to a portion of the bobbin 16. In this particular embodiment, the pole piece 54 has a reduced inner diameter flange 56 configured to overlap the armature 52 when the solenoid portion 12 is energized. Since the geometry of the flange 56 affects the distribution of the magnetic field generated by the excited coil 18, the desired proportional magnetic flux is achieved by the overlapping flange 56.

  FIG. 2 shows a cross-sectional plan view of one alternative embodiment of a configuration for a dual poppet low leakage valve. The alternative embodiment shown in FIG. 2 differs from the embodiment shown in FIG. 1 in the location of the pole pieces, flux tubes, springs and armature. FIG. 2 shows a pole piece 54 ′ that is a part of the hydraulic part 24. The pole piece 54 ′ has an increased diameter inner portion 56 ′ configured to overlap so that the magnetic features of the armature 52 can be matched. A spring 60 ′ is disposed between the armature 52 and the lower bearing 62. In this particular embodiment of the present invention, when the solenoid portion 12 is energized, the armature 52 moves in a first direction so that the secondary poppet 46 contacts the secondary valve seat 48. The next valve 44 is closed. At the same time, when the primary poppet 40 leaves the primary valve seat 42, the primary valve 38 opens. When the solenoid portion 12 is released from the excited state, the spring 60 'exerts a force on the armature 52 and the valve stem 34 slides in the second direction so that the primary poppet 40 contacts the primary valve seat 42. When the primary valve 38 is closed. At the same time, the secondary valve 44 opens when the secondary poppet 46 moves away from the secondary valve seat 48. Since the primary valve 38 is in the closed position when the solenoid portion 24b is released from the excited state, this valve is referred to as a normally closed valve. The action of the double poppet low leakage valve 10 'in this particular embodiment is that when the solenoid portion 12 is energized, the primary valve 38 opens and the secondary valve 44 closes. On the other hand, in FIG. 1, when the valve 10 is in an excited state, the primary valve 38 is closed and the secondary valve 44 is opened, which is the same as the embodiment shown in FIG.

  FIG. 3 shows one alternative embodiment of FIG. This particular embodiment includes a valve stem 34 having a large diameter portion 66 and a small diameter portion 68. The spring 60 extends between the lower bearing 62 and the shoulder 70. In this embodiment, the spring 60 does not extend into the solenoid portion 24b, and the spring acts directly on the valve shaft 34, not the armature 52. Similar to the valve shown in FIG. 2, the valve in this embodiment is also configured so that the primary valve 38 is in the closed position when the solenoid portion 24b is released from the excited state (ie, normally). Is closed).

  FIG. 4 shows one alternative embodiment of FIG. This particular embodiment includes a valve stem 34 having a large diameter portion 66 and a small diameter portion 68. The spring 60 extends between the upper bearing 64 and the armature 52. In addition, this embodiment includes a diaphragm 72 that functions to seal the solenoid portion 24b from the hydraulic valve portion 24a. Similar to the valve shown in FIG. 1, when the solenoid portion 24b is released from the excited state, the primary valve 38 is in the open position, so the valve shown in this particular embodiment is referred to as a normally open valve. Is done.

  The valve operating method described above allows the same pressure regulation function to be performed while reducing the amount of hydraulic fluid discharged and leaked to the reservoir as compared to conventional variable bleed solenoid valves. This is accomplished by an integral supply shutoff (secondary) valve 44 that operates with the discharge bleed (primary) valve 38. When low, secondary valve 44 prevents supply pressure from supply port 32 from entering control volume 30. When the solenoid 12 is activated, as the secondary poppet 46 moves away from the secondary valve seat 48, the secondary valve 44 opens, allowing supply pressure to enter the control volume 30, and the primary poppet 40. As the valve moves toward the primary valve seat 42, the primary valve 38 moves toward the closed position, thereby gradually reducing the amount of discharge leakage and increasing the pressure of the control volume 30 at the stroke distance limit point of the solenoid 12. Raise. When the primary poppet 40 approaches the surface of the primary valve seat 42, the secondary valve 44 is fully opened. At this time, the pressure in the control volume 30 reaches its maximum value, and the amount of discharge leakage becomes minimum.

  The description of the invention is merely exemplary in nature and, thus, variations that do not depart from the gist of the invention are intended to be included within the scope of the invention. Such variations are not to be regarded as a departure from the spirit and scope of the present invention.

It is a cross-sectional top view which shows the form of a double poppet low leak valve. FIG. 2 is a cut-away plan view of a first alternative embodiment of the secondary valve shown in FIG. 1. FIG. 6 is a cut-away plan view of a second alternative embodiment of the secondary valve shown in FIG. 1. FIG. 7 is a cutaway cross-sectional plan view showing a third alternative embodiment of the secondary valve shown in FIG. 1. It is a cross-sectional top view of 2nd embodiment which shows the form of a double poppet low leak valve. It is a cross-sectional top view which shows 3rd embodiment of this invention which has a valve shaft with a taper. It is a cross-sectional top view which shows another embodiment of this invention which has a diaphragm which seals a hydraulic part from a power provision part.

Explanation of symbols

10, 10 'Double Poppet Low Leakage Variable Bleed Solenoid Valve 12 Solenoid, Solenoid Part 14 Housing 16 Bobbin 18 Coil 20 End Cap 22 Discharge Port 24a Hydraulic Part 24b Solenoid Part 26 Valve Housing 28 Flux Tube 30 Control Volume 32 Supply Port 33 O-ring seal 34 Valve shaft 35 Second O-ring seal 36 Hollow passage 38 Primary valve / discharge bleed valve 40 Primary poppet 42 Primary valve seat 44 Secondary valve / supply shutoff valve 46 Secondary poppet 47 Projected nozzle 48 Secondary Valve seat 49 Tapered surface 50 Opening 51 Ring 52 Armature 54, 54 'Pole piece 56 Flange 56' Increased diameter inner portion 60, 60 'Spring 62 Lower bearing 64 Upper bearing 70 Shoulder 72 Diaphragm

Claims (16)

In solenoid valve,
A solenoid portion having a housing enclosing a bobbin wound with a coil; and a discharge passage disposed through one end of the housing;
A hydraulic part having a valve housing connectable to the solenoid part and a control volume connected to the hydraulic part;
A supply port connected through the valve housing of the hydraulic part;
A valve stem having an armature slidably disposed through the solenoid portion, wherein the bobbin is disposed annularly around the armature and extends from the solenoid portion into the hydraulic portion; A valve shaft having a first end disposed adjacent to and a second end disposed adjacent to the hydraulic portion;
A primary valve disposed at a first end of the valve stem;
A secondary valve disposed at a second end of the valve shaft, and when the valve shaft moves in a first direction, the secondary valve moves toward an open position and the primary valve The valve moves toward the closed position, and when moved toward the second position, the secondary valve moves toward the closed position, and the primary valve moves toward the open position. valve.   The solenoid valve according to claim 1, further comprising a hollow passage disposed through the valve shaft to allow fluid communication between the secondary valve and the primary valve.   3. The electromagnetic valve according to claim 2, wherein the hollow passage can viscously attenuate the valve shaft so as to improve the stability of the electromagnetic valve.   The solenoid valve of claim 1, further comprising an adjustable end cap disposed through the housing of the solenoid, wherein the drain port is disposed about the end cap. 5. The solenoid valve according to claim 4, wherein the primary valve includes a primary poppet formed around the first end of the valve shaft, and a primary valve formed on the end cap adjacent to the primary poppet. Formed from the
The secondary valve is formed of a secondary poppet formed around the second end portion of the valve shaft, and a secondary valve seat held in the hydraulic pressure portion, and the secondary valve seat An electromagnetic valve having an opening extending therethrough, wherein the secondary valve seat is disposed between the control volume and the supply port. The double poppet low leakage variable bleed solenoid valve according to claim 1,
Comprising a pole piece arranged annularly in the solenoid part adjacent to the bobbin;
The pole piece has a reduced inner diameter flange and is aligned with the armature and is configured to slidably surround the armature, the armature being surrounded by the bobbin and coil, thereby A dual poppet low leakage variable bleed solenoid valve, wherein the armature and the valve stem slide around a longitudinal axis of the valve stem in response to excitation of the solenoid portion. The solenoid valve according to claim 6,
One or more lower bearings disposed between the valve shaft and the housing, wherein the one or more lower bearings serve to facilitate sliding of the valve shaft;
A spring formed around the valve shaft and extending between the armature and the one or more upper bearings, and when the solenoid portion is de-energized, the spring An electromagnetic valve in which the valve shaft is slid by applying a force to the primary valve so that the primary valve is in an open position and the secondary valve is in a closed position. In solenoid valve,
A solenoid portion having a housing enclosing the coil assembly and an adjustable end cap disposed through the housing, the end cap having a discharge port disposed about the end cap; A solenoid portion having a surface to form;
A hydraulic part having a valve housing connectable to the solenoid part and a control volume formed in the hydraulic part;
A supply port connected through the valve housing of the hydraulic part;
A valve shaft slidably disposed through the solenoid portion, wherein the bobbin is disposed annularly around the valve shaft and extends from the solenoid portion into the hydraulic portion; One end ends at the solenoid portion and has a primary poppet formed around the first end, the second end of the valve stem ends at the hydraulic portion, A valve stem having a secondary poppet formed around the second portion;
A hollow passage disposed through the valve shaft to allow media to pass between the first end and the second end of the valve shaft;
A primary poppet seat held in the solenoid portion, wherein the primary valve seat is formed in the end cap adjacent to the primary poppet of the valve stem;
A secondary valve seat held in the hydraulic portion, having an opening extending through the valve seat, and disposed between the control volume and the supply port;
A pole piece annularly disposed in the solenoid portion adjacent to the bobbin, the pole piece having a reduced inner diameter flange;
An armature attached to the valve stem, the armature configured to be aligned with the reduced inner diameter flange of the pole piece and to be slidably inscribed in the flange; Is surrounded by the bobbin and coil, so that the armature and the valve stem are configured to slide longitudinally in response to excitation of the solenoid portion. The solenoid valve according to claim 8,
A spring formed around the valve shaft;
The electromagnetic valve is biased to move the secondary poppet in a direction in contact with the secondary valve seat, and the double poppet low-leakage electromagnetic valve is disposed in a normally closed position, that is, a normal high pressure position. The solenoid valve according to claim 8,
A spring formed around the valve shaft;
The electromagnetic valve is biased to move the primary poppet in a direction in contact with the primary valve seat and places the valve in a normally open position, that is, a normally low pressure position. Hydraulic pressure comprising a solenoid portion comprising a housing having a discharge passage disposed through the end of the housing, and a valve housing having a supply port connected through the valve housing and a control volume connected to the valve housing. A valve shaft that is slidably disposed through the solenoid portion and extends into the hydraulic portion; a primary valve disposed at a first end of the valve shaft within the solenoid portion; A method of operating a double poppet low leakage variable bleed solenoid valve comprising: a secondary valve disposed at a second end of the valve stem in a hydraulic portion;
Exciting the solenoid portion to slide the valve stem in a first direction;
When the valve stem moves in the first direction, simultaneously opening the secondary valve;
Simultaneously closing the primary valve when the valve stem moves in the first direction;
Fluid flow from the supply port to the control volume when the secondary valve opens;
Discharging excess pressure from the control volume through the primary valve to the discharge port until the primary valve reaches a fully closed position where the pressure in the control volume is at a maximum;
De-exciting the solenoid and sliding the valve stem in a second direction in response to a force applied to the armature by the compressed spring member;
Simultaneously closing the secondary valve when the valve stem moves in the second direction;
When the valve stem moves in the second direction, simultaneously opening the primary valve;
Discharging excess pressure from the control volume through the primary valve to the discharge port until the secondary valve reaches a fully closed position where the pressure in the control volume is at a minimum value, and A method of operating a heavy poppet low leakage variable bleed solenoid valve.   12. The method of claim 11, further comprising a hollow passage disposed longitudinally through a valve shaft between the secondary valve and the primary valve, wherein the step of flowing fluid comprises passing fluid to the secondary valve. The method further comprises flowing through the hollow passage to and from the primary valve. Hydraulic pressure comprising a solenoid portion comprising a housing having a discharge passage disposed through an end of the housing, and a valve housing having a supply port connected through the valve housing and a control volume connected to the valve housing. A valve shaft that is slidably disposed through the solenoid portion and extends into the hydraulic portion; a primary valve disposed at a first end of the valve shaft within the solenoid portion; A method of operating a double poppet low leakage variable bleed solenoid valve, comprising: a secondary valve disposed at a second end of the valve stem in a hydraulic portion;
Exciting the solenoid portion to slide the shaft in a direction toward the second end;
Simultaneously closing the secondary valve as the valve stem slides toward the second end;
When the valve stem moves toward the second end, simultaneously opening the primary valve;
Limiting the flow from the supply port to the control volume when the secondary valve is moved to a fully closed position and the primary valve is in a fully open position where the pressure in the control volume is at a minimum value; ,
De-exciting the solenoid and sliding the valve stem toward the first end in response to a force applied to the armature by the compressed spring member;
When the valve stem moves toward the first end, opening the secondary valve;
Closing the primary valve when the valve stem moves toward the first end;
Restricting the flow from the control volume through the primary valve to the discharge port until the primary valve reaches a fully closed position where the pressure in the control volume is at a maximum value. A method of operating a low-leakage variable bleed solenoid valve.   14. The method of claim 13, further comprising a hollow passage disposed longitudinally through the valve shaft between the secondary valve and the primary valve, wherein the step of flowing fluid comprises passing fluid to the secondary valve. The method further comprises flowing through the hollow passage to and from the primary valve. In the valve
A power applying portion having a housing;
A hydraulic part having a valve housing connectable to the housing of the power application part;
A valve shaft disposed through the hydraulic portion and extending into the power application portion, a first end ending in the power application portion, and a second end ending in the hydraulic portion A valve stem having
A primary valve disposed at the first end of the valve stem;
And a secondary valve disposed at the second end of the valve stem. In the valve
A power applying portion having a housing;
A hydraulic part having a valve housing connectable to the housing of the power application part;
A valve shaft disposed through the hydraulic portion and extending into the power application portion, the hollow shaft extending longitudinally through the valve shaft, wherein the valve shaft and the hollow passage are A valve stem having a first end ending in the power application portion and a second end ending in the hydraulic portion;
A primary valve disposed at the first end of the hollow passage;
A secondary valve disposed at the second end of the valve shaft, and when the valve shaft moves in a first direction toward the primary valve, the primary valve is directed toward a closed position. Movement, the secondary valve moves toward the open position, and when the valve stem moves in the second direction toward the secondary valve, the secondary valve moves toward the closed position, and the primary valve Is a valve that moves towards the open position.

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