WO2001014772A1

WO2001014772A1 - Zero axial motion spring retainer

Info

Publication number: WO2001014772A1
Application number: PCT/US2000/022606
Authority: WO
Inventors: Raul Armando Bircann; Dwight O. Palmer
Original assignee: Delphi Technologies, Inc.
Priority date: 1999-08-24
Filing date: 2000-08-18
Publication date: 2001-03-01

Abstract

A gas management valve (10) includes a metering subassembly (14), an actuator subassembly (12) coupled to the metering subassembly (14) and an elongate shaft (16). The shaft (16) has a first end and a second end. The first end is disposed within the actuator subassembly (12). The second end is disposed within the metering subassembly (14). The shaft (16) defines at least two recessed portions (42, 44) proximate the first end. The shaft (16) further defines at least two ridge portions (48, 50) proximate the first end. Each of the recessed portions (42, 44) is axially separated by one of the ridge portions (48, 50). One of the recessed portions (44) is disposed immediately adjacent the first end of the shaft (16).

Description

ZERO AXIAL MOTION SPRING RETAINER

CROSS-REFERENCE TO RELATED APPLICATIONS This application claims the benefit of U.S. Provisional Patent Application

Serial No. 60/150,424, filed August 24, 1999.

TECHNICAL FIELD

The present invention generally relates to gas management valves for use in internal combustion engines.

BACKGROUND OF THE INVENTION

Automobile emissions are said to be one of the most significant sources of pollution in numerous cities across the country. In order to minimize any impact upon the environment, and in order to meet stringent federal emissions standards, automobile manufacturers are continuously striving to reduce undesirable emissions and improve fuel economy. One method by which automobile manufacturers have attempted to improve fuel economy and reduce undesirable emissions is through increasing the efficiency and performance of gas management valves, such as, for example, exhaust gas recirculation (EGR) valves.

Exhaust gas recirculation (EGR) involves capturing the exhaust gas of an internal combustion engine, and recycling at least a portion of the captured exhaust gas back into the combustion chamber of the engine. Adding the exhaust gas to the combustion charge in the combustion chamber lowers the combustion temperature below the point at which nitrogen combines with oxygen, thereby reducing the level of undesirable emissions. EGR is accomplished by the use of EGR valves.

Conventional EGR valves, and gas management valves in general, include an electro-magnetic actuator coupled to a metering base. The metering base includes a metering chamber having a metering port. The metering chamber has an intake port and a metering port. The intake port is associated with a source of gas and provides a passageway for the flow of gas into the metering port. In the case of an EGR valve, the intake port is associated with a source of exhaust gas, such as, for example, the exhaust manifold. The metering port is connected to an intake manifold or intake vacuum of the engine, and provides a passageway for the flow of gas to exit the metering chamber. A shaft extends contiguously in an axial direction from the actuator, through the intake port into the metering chamber, and out the metering port. A metering poppet, which is a plunger-shaped member, is disposed at the end of the shaft proximate the metering port. In a default position, the metering poppet sealingly engages the metering port, thereby precluding flow of gas into the metering chamber. The metering port is opened when the shaft is reciprocated which, in turn, displaces the metering poppet from engagement with the metering port. Thus, the metering port is unsealed, and gas flows out the metering port into the engine.

The reciprocation of the shaft occurs by the magnetic actuator first drawing the shaft in an axial direction such that the metering poppet is displaced relative to the metering port thereby unsealing the metering port and allowing gas to flow therethrough.

After a predetermined amount of time, or a predetermined amount of travel of the shaft, the actuator is de-energized and the shaft is returned to the default or closed position by a return spring. The return spring applies an axially-directed force to the shaft which returns the metering poppet into sealing engagement with the metering port. Some gas management valves include a spring retention device, or spring retainer, which is typically attached to the end of the shaft which is opposite the metering poppet. The return spring is compressed between the spring retainer and a suitable anchoring point, such as, for example a journal bearing disposed around the actuator shaft.

In order to control the amount of gas flowing through a gas management valve, the exact position of the metering poppet must be known or determinable to a high degree of accuracy. Therefore, the attachment of the spring retainer to the shaft must be a secure mechanical connection which prevents substantially all axial movement or play of the spring retainer relative to the shaft. Even a slight amount of axial play of the spring retainer relative to the shaft introduces inaccuracy into determining the position of the metering poppet. Any uncertainty or inaccuracy in the position of the metering poppet can result in improper scheduling of the delivery of the combustion charge and/or the recycling of exhaust gas into the combustion chamber. Further, such inaccuracy in the determining or knowing the position of the shaft can result in emission levels which exceed federal standards. Conventional methods of attaching the spring retainer to the shaft reflect a tradeoff between the conflicting goals of reducing the complexity of the attachment device or method and reducing undesirable axial play between the spring retainer and shaft. For example, one method of attaching the spring retainer to the shaft uses a lock clip and washer arrangement. This method achieves a reasonably small amount of axial play, but is relatively complex from a manufacturing standpoint. The lock clip and washer are relatively small component pieces which are rather difficult to manipulate, especially in a high-volume manufacturing environment. Further, this method requires additional component pieces. It would be desirable to eliminate the added component pieces to thereby increase manufacturing efficiency and decrease cost. Moreover, although this arrangement achieves a reasonably small amount of axial play, its complexity has contributed to premature shaft failure. The spring retainer may also be attached to the shaft through a mechanical crimping process. The current method of mechanically crimping is relatively simple, but may fail to achieve acceptable levels of axial play. Furthermore, the current method of mechanical crimping is prone to become loose, resulting in unacceptably large amounts of axial play.

Therefore, what is needed in the art is an apparatus and method for attaching a spring retainer to a shaft which substantially eliminates axial movement of the spring retainer relative to the shaft.

Furthermore, what is needed in the art is an apparatus and method for attaching a spring retainer to a shaft which eliminates the need for additional component parts.

Moreover, what is needed in the art is a method and apparatus for attaching a spring retainer to a shaft which increases efficiency in manufacturing and thereby reduces manufacturing costs.

SUMMARY OF THE INVENTION The present invention provides a gas management valve for use with an internal combustion engine.

The invention comprises, in one form thereof, a metering subassembly, an actuator subassembly coupled to the metering subassembly, and an elongate shaft. The shaft has a first end and a second end. The first end is disposed within the actuator subassembly. The second end is disposed within the metering subassembly. The shaft defines at least two recessed portions proximate the first end. The shaft further defines at least two ridge portions proximate the first end. Each of the recessed portions is axially separated by one of the ridge portions. One of the recessed portions is disposed immediately adjacent the first end of the shaft. A spring retainer includes an aperture and a closed end opposite the aperture. The aperture and the closed end are interconnected by a cylindrical sidewall. The sidewall and the closed end define a cavity. The first end of the shaft is received within the cavity such that the first end of the shaft abuttingly engages the closed end of the spring retainer. At least two of the recessed portions are disposed within the cavity. The sidewall of the spring retainer is crimped into abutting engagement with the two recessed portions disposed within the cavity.

An advantage of the present invention is that there are no additional component parts required to securely fasten the spring retainer to the shaft.

Another advantage of the present invention is that axial motion or play of the spring retainer relative to the shaft is substantially eliminated without the use of additional component parts for attaching the spring retainer to the shaft.

BRIEF DESCRIPTION OF THE DRAWINGS

The above-mentioned and other features and advantages of this invention, and the manner of attaining them, will become apparent and be better understood by reference to the following description of one embodiment of the invention in conjunction with the accompanying drawings, wherein: FIG 1 is a sectional view of a gas control valve which includes one embodiment of a zero axial motion spring retainer and shaft of the present invention;

FIG. 2 is a perspective, partially sectioned view of the zero axial motion spring retainer and shaft of Fig. 1;

FIG. 3 is a partially sectioned, detail view of the zero axial motion spring retainer and shaft of Fig. 1 ;

FIG. 4 is a sectioned view of a first embodiment of a zero axial motion spring retainer of the present invention;

FIG. 5 is a sectioned view of a second embodiment of a zero axial motion spring retainer of the present invention; FIG 6 illustrates the forces used to attach and the axial strains which act to securely retain the zero axial motion spring retainer of Figs. 1-5 to the shaft of the present invention;

FIG 7 is a perspective view of an alternate embodiment of a shaft of the present invention; FIG 8 is a sectional view of Fig. 7;

FIG 9 is a perspective view of a further alternate embodiment of a shaft of the present invention; and

FIG 10 is a sectional view of Fig. 9. Corresponding reference characters indicate corresponding parts throughout the several views. The exemplification set out herein illustrates one preferred embodiment of the invention, in one form, and such exemplification is not to be construed as limiting the scope of the invention in any manner.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring now to the drawings and particularly to Fig. 1, there is shown a gas management valve having one embodiment of a zero axial motion spring retainer of the present invention.

Gas control valve 10 includes actuator subassembly 12, metering subassembly 14, shaft 16, metering port 20 and outlet port 22. Metering poppet 24 is disposed at one end of shaft 16 and is associated with metering port 20. Zero axial motion spring retainer 30 is secured, as will be described with more particularity hereinafter, at the end of shaft 16 which is opposite metering poppet 24 and which is associated with actuator 12. Gas control valve 10 is typically bolted or otherwise attached to internal combustion engine 32 such that metering port 20 is in fluid communication with an intake port (not shown) of internal combustion engine 32. In a default position, metering poppet 24 is in sealing engagement with metering port 20, thereby preventing the flow of gas through metering port 20 and out outlet port 22. Actuator 12 is energized to reciprocate shaft 16 in an axial direction toward internal combustion engine 32 to selectively disengage metering poppet 24 from sealing engagement with metering port 20. Thus, gas is permitted to flow in through metering port

20, out through outlet port 22, and into the intake port (not shown) of internal combustion engine 32. Return spring 34 is disposed intermediate spring retainer 30 and journal bearing 36. As shaft 16 is reciprocated toward engine 32, return spring 34 is compressed. After a predetermined amount of time, or after shaft 16 has traveled a predetermined distance, actuator 12 is de-energized. Return spring 34 biases shaft 16 in an axial direction away from internal combustion engine 32, thereby returning metering poppet 24 into sealing engagement with metering port 20. Thus, the flow of gas from metering port 20 through outlet port 22 and into the intake port of internal combustion engine 32 is precluded. Referring now to Figs. 2 and 3, shaft 16 and spring retainer 30 are shown in an assembled condition, and in greater detail. Shaft 16 is an elongate member, and includes metering poppet 24 at one end thereof. At the other end thereof, shaft 16 includes two recessed portions 42 and 44. Recessed portions 42 and 44 are each configured as, for example, grooves having a predetermined axial length and which extend around the circumference of shaft 16. Each of recessed portions 42 and 44 have a diameter D that is a predetermined amount less than the diameter S of shaft 16. Shaft 16 further includes ridge portions 46, 48 and 50. Each of ridge portions 46, 48 and 50 are configured as, for example, having a predetermined axial length and extending around the entire circumference of shaft 16. Recessed portion 42 is disposed intermediate ridge portion 46 and 48, and recessed portion 44 is disposed intermediate ridge portion 48 and ridge portion 50. Each of ridge portions 46, 48 and 50 have a diameter R that is a predetermined amount smaller than diameter S of shaft 16 and a predetermined amount larger than diameter D of recessed portions 42 and 44. Shaft 16 includes chamfered portion 16a adjacent ridge portion 46. Ridge portion 46 includes chamfered edge 46a. Ridge portion 48 includes chamfered edges

48a and 48b. Ridge portion 50 includes chamfered edge portion 50a adjacent recessed portion 44, and chamfered end portion 52. Shaft 16 is constructed of, for example, stainless steel or aluminum.

Referring now to Figs. 4 and 5, zero axial movement spring retainer 30 is an elongate tubular member having flange portion 56, sidewall 58, closed end 60 and aperture

62. Sidewall 58 is substantially cylindrical, and in conjunction with closed end 60 defines cavity 64. Spring retainer 30 is constructed of, for example, stainless steel, aluminum, or other suitable material. Spring retainer 30 is placed over shaft 16 and engages shaft 16 in, for example, a slight press fit or a slide fit. More particularly, spring retainer 30 is placed onto shaft 16 by aligning aperture 62 with chamfered end portion 52 of shaft 16. Spring retainer

30 is then pressed or slid over and down shaft 16 until closed end 60 of spring retainer 30 abuttingly engages chamfered end portion 52, thereby fully seating spring retainer 30 on shaft 16.

When configured for a slide fit with shaft 16, spring retainer 30 is constructed or fabricated with a substantially straight sidewall 58, as shown in Fig. 4. When configured for a press or snap fit, spring retainer 30 is constructed or fabricated as having a sidewall 58 with pre-formed indented or concave regions 74 and 76 extending around at least a portion of the circumference of sidewall 58, as shown in Fig. 5. Such pre-formed indented or concave regions 74, 76 provide a press fit or snap fit of spring retainer 30 onto shaft 16. As spring retainer 30 is pressed over ridge portions 46, 48 and 50, concave regions 74 and 76 engage and snap over chamfered end portion 52 and chamfered edges 46a, 48 a, 48b and 50a. Chamfered end portion 52 and chamfered edges 46a, 48a, 48b and 50a lower the force required to elastically deform concave regions 74 and 76 and thereby the force required to snap or press fit of spring retainer 30 onto shaft 16. In addition to enabling a snap or press fit, concave regions 74 and 76 of spring retainer 30 also provide a guide or target for the subsequent use and alignment of a crimping tool to securely affix spring retainer 30 onto shaft 16.

Once spring retainer 30 is fully seated onto shaft 16, spring retainer 30 is securely affixed to shaft 16 by mechanical crimping of sidewall 58 into recessed portions 42 and 44. More particularly, and as shown in Fig. 6, spring retainer 30 is crimped into recessed portion 44 of shaft 16 by applying predetermined force Fl to sidewall 58 proximate to recessed region 44. Application of force Fl creates crimped region 58a in sidewall 58 proximate to recessed region 44. Applied force Fl causes crimped region 58a to engage recessed portion 44 and chamfered edges 50a, 48b of shaft 16. Applied force Fl is opposed by reaction force F2, and creates axial strain 1 in sidewall 58. When applied force Fl is removed, some partial relief in axial strain 1 occurs. The partial strain relief in axial strain

1 , results in a degree of relaxation, or springback, of crimped region 58a in a direction away from recessed region 44 and chamfered edges 50a, 48b. The springback of crimped region 58a results in a degree of undesirable axial movement or axial play of spring retainer 30 relative to shaft 16. A predetermined force F3 is applied to sidewall 58 in the region proximate recessed portion 42. Application of force F3 creates crimped region 58b in sidewall 58 proximate to recessed region 42. Applied force F3 causes crimped region 58b to engage recessed portion 42 and chamfered edges 48a, 46a of shaft 16. Applied force F3 creates axial strain 2 in sidewall 58 proximate to ridge region 48 of shaft 16. When applied force F3 is removed, partial relief occurs in axial strain 2. However, the partial strain relief in axial strain 2 , rather than resulting in undesirable axial movement or axial play of spring retainer 30 relative to shaft 16, results in a secure mechanical coupling between spring retainer 30 and shaft 16. The partial strain relief in axial strain 2, essentially pulls crimped region 58a into abutting engagement with chamfered edge 48b and crimped region 58b into abutting engagement with chamfered edge 48a, thereby eliminating substantially all axial movement or play of spring retainer 30 relative to shaft 16. Thus, spring retainer 30 is effectively and substantially locked in a fixed axial position relative to shaft 16, and is securely attached thereto. In use, spring retainer 30 is securely affixed, as described hereinabove, to shaft 16. Return spring 22 is compressed in between flange portion 56a and journal bearing 28 (see Fig. 1). Actuator 12 reciprocates shaft 16 such that metering poppet 24 disengages from sealing engagement with metering port 20. Thus, gas is free to flow in metering port 20 and through outlet port 22. When actuator 12 is de-energized, return spring 34 exerts an axially- directed force upon spring retainer 30 to thereby return metering poppet 24 into sealing engagement with metering port 20. Substantially no relative motion occurs between spring retainer 30 and shaft 16. Thus, the exact position of metering poppet 24 relative to metering port 20 is known or is determinable at all times by, for example, pintle position sensor 37 (Fig. 1) which is in intimate contact with spring retainer 30.

In the embodiment shown, shaft 16 includes two recessed regions 42 and 44, with corresponding ridge regions 46, 48, 50. However, it is to be understood that the shaft may be alternately configured, such as, for example, with a plurality of recessed regions and corresponding ridge regions. In the embodiment shown, shaft 16 is configured as having ridge regions 46,

48, 50 and recessed regions 42, 44, each having a diameter that is a predetermined amount less than the diameter of shaft 16. However, it is to be understood that the shaft may be alternately configured, such as, for example, as having ridge regions and/or recessed regions having respective diameters that are greater than the shaft diameter. In the embodiment shown, each of recessed portions 42, 44 and ridge portions

46, 48, 50 of shaft 16 have a predetermined axial length. However, it is to be understood that the shaft may be alternately configured, such as, for example, having recessed portions and/or ridge portions of different predetermined axial lengths.

In the embodiment shown, each of recessed portions 42, 44 extend around the entire circumference of shaft 16. However, it is to be understood that the shaft may be alternately configured, such as, for example, with recessed and/or ridge portions which do not extend contiguously around the circumference of the shaft. For example, the recessed portions may, as shown in Figs. 7 and 8, be configured in the form of notch sections 80a, 80b, 82a, 82b that are formed on diametrically opposed sides of shaft 16 or which otherwise extend only partially around the circumference of shaft 16. As a further example, the ridge portions may, as shown in Figs. 9 and 10, be configured as ridge sections 84a, 84b, 86a, 86b, 88a, 88b which do not extend contiguously around the circumference of shaft 16.

In the embodiment shown, chamfered edges 46a, 48a, 48b, 80a and/or chamfered end portion 52 are configured as chamfered edges and a chamfered end, respectively. However, it is to be understood that all or any desired combination of the chamfered edges and/or chamfered end may be alternately configured, such as, for example, as radiused surfaces.

While this invention has been described as having a preferred design, the present invention can be further modified within the spirit and scope of this disclosure. This application is therefore intended to cover any variations, uses, or adaptations of the present invention using the general principles disclosed herein. Further, this application is intended to cover such departures from the present disclosure as come within the known or customary practice in the art to which this invention pertains and which fall within the limits of the appended claims.

Claims

What is Claimed:

1. A gas management valve comprising: a metering subassembly; an actuator subassembly coupled to said metering subassembly; an elongate shaft having a first end and a second end, said first end disposed within said actuator subassembly, said second end disposed within said metering subassembly, said shaft defining at least two recessed portions proximate said first end, said shaft further defining at least two ridge portions proximate said first end, each of said at least two recessed portions being axially separated by one of said at least two ridge portions, one of said at least two recessed portions being disposed immediately adjacent said first end of said shaft; and a spring retainer having an aperture and a closed end opposite said aperture, said aperture and said closed end interconnected by a substantially cylindrical sidewall, said sidewall and said aperture defining a cavity, said first end of said shaft being received within said cavity such that said first end of said shaft abuttingly engages said closed end of said spring retainer, at least two of said at least two recessed portions being disposed within said cavity, said sidewall of said spring retainer configured for being crimped into abutting engagement with each of said at least two recessed portions disposed within said cavity of said spring retainer.

2. The gas management valve of claim 1 , wherein each of said at least two ridge portions has a ridge diameter, each of said at least two recessed portions has a recess diameter, said ridge diameter being a predetermined amount greater than said recess diameter.

3. The gas management valve of claim 1 , wherein each of said at least two ridge portions includes chamfered edges, each of said chamfered edges disposed immediately adjacent a respective one of said at least two recessed portions, said spring retainer configured for being crimped into abutting engagement with each of said chamfered edges.

4. The gas management valve of claim 1, wherein said first end of said shaft is one of chamfered and radiused.

5. The gas management valve of claim 1, wherein each of said at least two ridge portions extend contiguously around a circumference of said shaft.

6. The gas management valve of claim 1, wherein each of said at least two ridge portions comprise a respective first and second ridge section, each of said first and said second ridge section extending around a respective portion of a circumference of said shaft.

7. The gas management valve of claim 6, wherein each said first ridge section is diametrically opposed to a coπesponding said second ridge section.

8. The gas management valve of claim 1, wherein each of said at least two recessed portions extend contiguously around a circumference of said shaft.

9. The gas management valve of claim 1, wherein each of said at least two recessed portions comprise a respective first and second notch section, each said first and second notch section extending around a portion of a circumference of said shaft.

10. The gas management valve of claim 9, wherein each said first notch section is diametrically opposed to a corresponding said second notch section.

11. The gas management valve of claim 1 , further comprising a metering poppet being one of attached to or defined by said second end of said shaft.

12. A metering subassembly for a gas management valve, compnsmg: an outlet port; a metering port in fluid communication with said outlet port; an elongate shaft extending through said metering port, said shaft having a first end and a second end, said shaft defining at least two recessed portions proximate said first end, said shaft further defining at least two ridge portions proximate said first end, each of said at least two recessed portions being axially separated by one of said at least two ridge portions, one of said at least two recessed portions being disposed immediately adjacent said first end of said shaft.

13. The metering subassembly of claim 12, further comprising a spring retainer having an aperture and a closed end opposite said aperture, said aperture and said closed end interconnected by a substantially cylindrical sidewall, said sidewall and said closed end defining a cavity, said spring retainer configured for receiving said shaft in said cavity such that at least two of said at least two recessed portions are disposed within said cavity, said sidewall configured for being crimped into abutting engagement with each of said at least two recessed portions disposed within said cavity.

14. A spring retainer, comprising: a substantially cylindrical sidewall having an aperture and a closed end, said aperture being disposed opposite said closed end, said sidewall and said closed end defining a cavity, said spring retainer configured for receiving a first end of a shaft within said cavity such that the first end of the shaft abuttingly engages said closed end of said spring retainer, said sidewall of said spring retainer configured for being crimped into abutting engagement with the shaft.

15. The spring retainer of claim 14, wherein said sidewall defines at least two concave regions, each of said at least two concave regions configured for being crimped into abutting engagement with corresponding regions on the shaft.

16. The spring retainer of claim 14, further comprising a flange, said flange disposed proximate said aperture.

17. An elongate shaft for a gas management valve, comprising: a first end configured for being disposed within an actuator subassembly of the gas management valve; a second end configured for being disposed within a metering subassembly of the gas management valve; and said shaft defining at least two recessed portions proximate said first end, said shaft further defining at least two ridge portions proximate said first end, each of said at least two recessed portions being axially separated by one of said at least two ridge portions, one of said at least two recessed portions being disposed immediately adjacent said first end of said shaft.

18. The shaft of claim 17, wherein each of said at least two ridge portions has a ridge diameter, each of said at least two recessed portions has a recess diameter, said ridge diameter being a predetermined amount greater than said recess diameter.

19. The shaft of claim 17, wherein each of said at least two ridge portions includes chamfered edges, each of said chamfered edges disposed immediately adjacent a respective one of said at least two recessed portions.

20. The shaft of claim 17, wherein said first end of said shaft is chamfered.

21. The shaft of claim 17, wherein each of said at least two ridge portions extend contiguously around a circumference of said shaft.

22. The shaft of claim 17, wherein each of said at least two ridge portions comprise a respective first and second ridge section, each of said first and said second ridge section extending around a respective portion of a circumference of said shaft.

23. The shaft of claim 22, wherein each said first ridge section is diametrically opposed to a corresponding said second ridge section.

24. The shaft of claim 17, wherein each of said at least two recessed portions extend contiguously around a circumference of said shaft.

25. The shaft of claim 17, wherein each of said at least two recessed portions comprise a respective first and second notch section, each said first and second notch section extending around a portion of a circumference of said shaft.

26. The shaft of claim 25, wherein each said first notch section is diametrically opposed to a corresponding said second notch section.

27. The shaft of claim 17, further comprising a metering poppet being one of attached to or defined by said second end of said shaft.

28. An internal combustion engine, comprising: a gas management valve, including: a metering subassembly; an actuator subassembly coupled to said metering subassembly; an elongate shaft having a first end and a second end, said first end disposed within said actuator subassembly, said second end disposed within said metering subassembly, said shaft defining at least two recessed portions proximate said first end, said shaft further defining at least two ridge portions proximate said first end, each of said at least two recessed portions being axially separated by one of said at least two ridge portions, one of said at least two recessed portions being disposed immediately adjacent said first end of said shaft; and a spring retainer having an aperture and a closed end opposite said aperture, said aperture and said closed end interconnected by a substantially cylindrical sidewall, said sidewall and said closed end defining a cavity, said first end of said shaft being received within said cavity such that said first end of said shaft abuttingly engages said closed end of said spring retainer, at least two of said at least two recessed portions being disposed within said cavity, said sidewall of said spring retainer being crimped into abutting engagement with each of said at least two recessed portions disposed within said cavity.

29. A method of attaching a spring retainer to a shaft of a gas management valve, comprising the steps of: receiving within said spring retainer said shaft, such that an end of said shaft abuts a closed end of said spring retainer; and crimping a sidewall of said spring retainer in at least two places, said at least two places corresponding to recessed portions formed on said shaft.

30. The method of attaching a spring retainer to a shaft of a gas management valve of claim 29, wherein said crimping step further comprises crimping said wall into abutting engagement with at least two chamfered edges formed on said shaft immediately adjacent said recessed portions.

31. A method of assembling a gas management valve, said gas management valve having a metering subassembly and an actuator subassembly, said method comprising the steps of: receiving within a spring retainer a shaft of said gas management valve, such that an end of said shaft abuts a closed end of said spring retainer; crimping a sidewall of said spring retainer in at least two places, said at least two places corresponding to recessed portions formed on said shaft; receiving at least a portion of said shaft and said spring retainer within said actuator subassembly; and coupling said actuator subassembly to said metering subassembly.

32. The method of attaching a spring retainer to a shaft of a gas management valve of claim 31, wherein said crimping step further comprises crimping said wall into abutting engagement with at least two chamfered edges formed on said shaft immediately adjacent said recessed portions.