US3802322A

US3802322A - Bellows

Info

Publication number: US3802322A
Application number: US00098669A
Authority: US
Inventors: N Johnson; E Trimble
Original assignee: EG&G Sealol Inc
Current assignee: EG&G Sealol Inc
Priority date: 1970-12-16
Filing date: 1970-12-16
Publication date: 1974-04-09
Anticipated expiration: 1991-04-09

Abstract

The invention relates to expansible bellows and features a construction wherein the chambers of each convolution expand and/or contract an equal distance throughout the longitudinal length of the bellows. The construction also prevents radial distortion throughout the length of the bellows.

Description

United States Patent 1191 11] 3,802,322 Johnson et al. 1 Apr. 9, 1974 BELLOWS 2,177,674 10/1939 Schweizer 92/43 x 1751 1111911919 Nor-11111 E1911 1011-1511-1199 31213333?) 1311325 $212221???"'"iiijiiiiiiii35533;? Bfifrmgton; Edward Franc 2,919,102 12/1959 Peters 92/39 x I Trun C m both of 1, 2,965,137 12/1960 LeESOII et al. 92 43 x 3,07 ,348 l 1963 All Us. [73] Asslgnee: Seam warwlck 3,36%,037 1/1968 Liki lec 9221 3)? [22] Filed: Dec. 16, 1970 [21] APP] 98,669 Prirnary ExaminerLaurence M. Goodridge 1 Asszstant Exammer-Ronald B. Cox Attorney, Agent, or Firm-William Frederick Werner [52] US. Cl 92/39, 92/34, 92/42,

92/43 [51] Int. Cl. Flb 19/00, F16j 3/00 [57] ABSTRACT [58] d of Search 92/34 The invention relates to expansible bellows and features a construction wherein the chambers of each convolution expand and/or contract an equal distance [56] References cued throughout the longitudinal length of the bellows. The UNITED STATES PATENTS construction also prevents radial distortion throughout 3,166,658 1/1965 Jennings 92/34 X the length of the bellows. 2,277,491 3/1942 Huber 92/43 X 1,751,193 311930 Dillman 9'2/43 9 Claims, 6 Drawing Figures /6 Z0 88 /0 l 4? 2 v 80 8/ Q7/ K A A 42 M v y\: 1 6 7 v I A I 1 r l 4 9 s I 1 a 1 1 4- 1223177711 971.1119 v7 A -\-I-W 636/ 72 60 36 52 /7 J5 1 P'MENTEUAPR 9 I974 $802,322

sum 1 OF 4 64 2: Q M A,

@563 sat 72 60 J6 52 /7 55 INVENTORS NORMAN ELTON JOHNSON E QYWARD FRANCIS TRIMBLE ATTORNEY PATENTEDAPR 91914 7 3.302.322

sum 2 er 4 INVENTORS ,F I G. 4 NORMAN ELTON JOHNSON WARD FRANCIS TRIMBLE ATTORNEY PATENIEUAPR 919m sum 3 OF 4- x N\NMI \N QN W WWW/WNW INVENTORS NORMAN ELTON JOHNS Fig/WARD FRANCIS TRIM E ATTORNEY This invention relates to expansible bellows and more particularly to a construction wherein mechanical means expands or contracts each convolution uniformly throughout the length of the bellows. In another form fluid pressure, acting in each chamber of each convolution, will expand and/or contract each convolution uniformly throughout the length of the bellows. The present construction also prevents radial distortion of the bellows.

An object of the present invention is to provide consistant pitch between convolutions of a bellows subject to internal and/or external high fluid pressure or by mechanical means as the convolutions expand or contract.

Another object of the present invention is to provide a bellows construction wherein the bellows will withstand greater expanding stresses and/or fluid pressures, internally and/or externally of the bellows, beyond prior bellows constructions.

In relatively long bellows the convolutions on opposite ends of the bellows are the first to react in expansion.

The greater the length of the bellows the greater the expansible strain on the outer end convolutions and the greater the tendency of one convolution reacting differently to pressure than adjacent convolutions.

Conversely, the fewer the number of convolutions in a series constituting a bellows; the pitch between convolutions in the series remains uniform, thus providing a more rigid bellows in which the convolutions react uniformly.

In a bellows constituting a multiple series of convolu tions there develops the undesirable condition of radial distortion of the convolutions.

Where, for example, the internal fluid pressure is relatively great, the disk walls of the convolutions under maximum stretch, rupture to destroy the effectiveness of the bellows.

In a valve, or rotary mechanical fluid seal, or breather tube assembly with thermal expansion, or in a high pressure steam line expansion joint, bellows are employed to provide longitudinal or axial pressure to cooperating parts while simultaneously providing a fluid seal, either internally or externally of the bellows. The degree of axial motion is generally determined by the length of the bellows. The greater the force needed the longer the bellows.

Applicant has provided a novel construction wherein a given force required in a bellows can be provided in a bellows of shorter length than heretofore, with the consequent elimination of radial distortion.

Another advantage is that a given size bellows will withstand a far greater internal or external pressure due to the more uniform expansion of all the convolutions, in a series of convolutions, constituting the bellows.

Other objects of the present invention will become apparent in part and be pointed out in part in the following specification and claims.

FIG. 1 is a side elevational view of the new and improved bellows;

FIG. 2 is a left end view of FIG. 1;

FIG. 3 is a fragmentary medial sectional view through a valve, showing the valve in seated or closed position and showing the bellows in compressed position;

FIG. 4 is a vertical medial cross sectional view through a valve, showing the valve in open position and showing the bellows in expanded condition;

FIG. 5 is a modified form of construction for the new and improved bellows, as applied to an expansion joint;

FIG. 6 is a medial sectional view showing a modified form of bellows applied to a valve construction.

In proceeding with this invention, there is illustrated in FIGS. 1 and 2, the new and improved bellows.

FIGS. 3 and 4 show the bellows of FIGS. 1 and 2 applied to a valve consisting of a body 10 having a medial well 11 provided with a valve seat 12. An inlet 13 in body 10 communicates with the bottom of well 11 below valve seat 12. An outlet 14 in body 10 communicates with well 11 above valve seat 12. Body 10 has an upstanding wall 15 which forms a chamber 16 in communication with the top of well 11.

An intermediate bonnet 17 is fastened to body 10 as by means of welding, shown at 18. Bonnet 17 is hollow so as to provide a space to form a continuation of chamber 16. The internal wall 20 of bonnet 17 is provided with a plurality of guide stops, illustrated as two in number, vis, lower guide stop 21 and upper guide stop 22.

A bonnet 23 is fastened to intermediate bonnet 17 as by welding, as shown at 24. Bonnet 23 is provided with an axial wall 25 which provides a space in continuation of chamber 16. v

A yoke 27 is fastened to bonnet 23, as by welding, shown at 28. Yoke 27 consists of a base 30 and a top flange 31 connected by two

arms

32 and 33. Base 30 is provided axially with a bearing 34, a cavity 35 and a bore 36. The bottom 37 of base 30 terminates one end of chamber 16.

A valve stem 40 provided with screw threads 41 and an enlarged flange 42 is rotatively supported in bearing 34 and is rotatively supported and engages screw threads 43 located-in bore 36.

A hand wheel 45 is fastened to the end of valve stem 40 by means of a nut 46 rotatively engaging threads 47 provided upon the end of valve stem 40. A washer 48 is interposed between nut 46 and hand wheel 45.

Fluid packing 50 is placed in cavity 35. A gland 51 surrounding valve stem 40 forces said packing 50 tightly into cavity 35 and around valve stem 40 to create fluid tight integrity.

A valve stem extension 52 is provided with a reduced diameter threaded area 53, a shoulder 54, a first step 55, a second step 56 and a threaded area 57. An upper bellows adapter is rotatively fastened to threaded area 57. A set screw 58 rotatively positioned in adapter 60 locks adapter 60 to threaded area 57. A rim 6] is provided upon extension 52. A holding nut 63 having an axial perforation 64 and a socket 65 is passed along valve stem 40 through axial perforation 64 until the wall 66 of socket 65 bears against the top surface 67 of enlarged flange 42. The lower end 70 of valve stem 40 bears against the top surface 71 of upper bellows adapter 60. The lower end wall 72 of socket 65 rests against rim 61. A set screw 75 rotatively mounted in holding nut 63 locks upper bellows adapter 60 to holding nut 63.

A bellows, generally indicated at 80, of a preselect number of convolutions 81 has the end convolution on one end fastened to upper bellows adapter 60 and the end convolution on the opposite end fastened to an upper spacing collar 82. Similarly, a bellows, generally indicated at 83, of a preselected number of convolutions 84 has the end convolution on one end fastened to upper spacing collar 82 and the end convolution on the opposite end fastened to a lower spacing collar 85. Similarly, a bellows, generally indicated at 86, of a preselected number of convolutions 87 has the end convolution on one end fastened to lower spacing collar 85 and the end convolution on the opposite end fastened to a lower bellows adapter 88. Lower bellows adapter 88 is a round flange having a seat 90 to which the bellows 86 is fastened and an upstanding side 91 which is welded to intermediate bonnet 17 at 92.

A valve plug 100 provided with a valve face 101 is fastened to the end of valve stem extension 52 by means of reduced diameter threaded end 53 and abuts shoulder 54. Valve plug 100 is located in well 11, and as will presently appear, valve face 101 engages and disengages valve seat 12.

Bellows 80, 83, 86 and upper and

lower spacing collars

82, 85, respectively, and lower bellows adapter 88 surround valve stem extension 52 and are located in chamber 16. An annular recess 94 is provided in lower bellows adapter 88.

Reference is now made to FIG. 4, wherein is shown the new and improved bellows construction applied to a valve fastened in a high pressure fluid line. The valve is illustrated in valve open position. That is, fluid entering inlet 13 will flow into well 11 past valve seat 12 and valve face 101 and into outlet 14.

It will be noted that lower bellows adapter 88 fastened to intermediate bonnet l7 divides chamber 16 into two regions. As shown, one region permits the fluid which flows around valve plug 100 in well 11 to flow through annular recess 94 to the inside of

bellows

80, 83 and 86 where the fluid is trapped by the bottom of upper bellows adapter 60 and by the fastening of lower bellows adapter 88 to intermediate bonnet 17 which is fastened to body at wall 15.

The region between the outside surfaces of the

bellows

80, 83, 86 and lower spacing collar 85, upper spacing collar 82 and the outside surfaces of upper bellows adapter 60 and holding unit 63 is subject to atmospheric pressure.

As shown in FIG. 4, the

bellows

80, 83, 86 are in extended position with upper spacing collar 82 engaging upper guide stop 22 and also engagin second step 56. In like manner, lower spacing collar 85 is in engagement with lower guide stop 21 and is also in engagement with first step 55. In this manner, bellows 80 and 83 through

spacing collars

82, 85 engaging second step 56, and first step 55, respectively, yielding urge valve stem extension 52 downwardly, in a direction to force valve face 101 against valve seat 12. The engagement of screw threads 41 with bushing 43 holds valve plug 100 in selected position; open or closed.

In FIG. 4, the valve is shown in open position. In FIG. 3, the valve plug 100 is shown in closed position with valve face 101 in engagement with valve seat 12.

With continued reference to FIG. 3, it will be noted that hand wheel 45 having been rotated to place the valve in closed position; has lowered valve stem extension 52, thereby to move both first step 55 and second step 56 downwardly, away, respectively, from lower spacing collar 85 and upper spacing collar 82. Because lower bellows adapter 88 is fastened to intermediate bonnet 17, upper bellows adapter 60 compresses bellows 80, 83, 86.

Because the required bellows expansible motion is provided in three

bellows sections

80, 83, 86, all the convolutions in all the bellows sections expand or contract uniformly, instead of merely the end convolutions reaching maximum expansion or contraction and then sequentially transfering the stress to the next adjacent convolution, as would happen if one bellows was provided in place of the present three

sections

80, 83, 86.

The mechanical extension of the three bellows sections has just been described to show how each convolution is mechanically expanded or contracted.

In this embodiment the sectional bellows may serve the additional function of a fluid seal.

The bellows 80, 83, 86 are provided to confine the fluid under very high pressure to region No. 1 of chamber 16. Should the fluid escape to region No. 2 of chamber 16 the fluid could escape to the atmosphere as it flowed past packing 50.

The fluid flowing past annular recess 94 will act in the cylindrical depression 103 formed by

sides

104, 105 of one convolution of bellows 86. Because the bellows, as illustrated, is sectionalized into three

sections

80, 83, 86 the convolutions will all expand and contract uniformly. Therefore, the fluid pressure acting in cylindrical depression 103 and upon

sides

104, 105 will encounter a convolution which has not been stretched to its elastic limit before other convolutions in the bellows have been stretched an equal amount. In this way, the sectionalized bellows will withstand greater fluid pressures than a single bellows of the same length.

Reference is now made to FIG. 6, wherein, hydraulic expansion is achieved in uniform manner upon the sectionalized convolutions.

The valve shown in FIG. 6 is of substantially the same construction as the valve shown in FIGS. 1, 2, 3 and 4 with the exception of the mechanism and structure associated with the bellows. The same reference numerals are used throughout FIGS. 1, 2, 3, 4 and 6 where the structures are the same.

The first structural difference in FIG. 6 is found in the valve stem extension 52A which is provided with a uniform diameter and intermediate bonnet 17 is provided internally with circular abuttments 110, 11]. Valve plug 100 having valve face 101A is fastened to valve stem extension 52A in fluid tight relationship. A valve seat 12A and well 11A are provided in body 10 shown as an integral part of intermediate bonnet 17.

An upper spacing collar 82A is provided with a clearance orifice 112 for free sliding movement relative to valve stem extension 52A. A bellows A, with a preselected number of convolutions and a preselected mean diameter or piston diameter, indicated by dot and dash lines 114, is fastened on one end to upper bellows adapter 60 and is fastened on the other end to upper spacing collar 82A.

A lower spacing collar A is provided with a clearance orifice 115 for free sliding movement relative to valve stem extension 52A. A bellows 83A with a preselected number of convolutions and a preselected mean diameter or piston diameter, indicated by dot and dash lines 117, is fastened on one end to upper spacing collar 82A and is fastened on the other end to lower spacing collar 85A.

A bellows 86A with a preselected number of convolutions and a preselected mean diameter or piston diameter, indicated by dot and sash lines 118, is fastened on one end to lower spacing collar 85A and is fastened on the other end to lower bellows adapter 88.

It is apparent that fluid in well 11 will flow around valve plug 100 into chamber 16A and engage the inside surface of the convolutions forming bellows 86A. The fluid will continue to flow through orifice 115 into the inside of bellows 83A, and then flow through orifice 112 to the inside of bellows 80A and be trapped by sur face 60B of adapter 60.

It will be observed that piston diameter 114 is smaller than piston diameter 117 and that piston diameter 17 is smaller than piston diameter 1 18. In this manner, the several bellows each have a different internal diameter so as to create different piston areas within each bellows.

This difference in piston areas causes the spacing collars 82A and 85A into contact with the upper stop guide 111 and the lower stop guide 110, respectively, and this restricts the extended length of individual bellows sections 80, 83A, and 86A.

As previously stated, an object of the present invention is to sectionalize a bellows of a given length so that each convolution of each section will expand uniformly.

The bellows by means of spacing collars are being limited in the degree of expansion, so as to prevent a convolution from exceeding its elastic limit, whereby, fluid under great pressure, acting on the convolutions would cause the convolution under elastic limit stress,

to rupture.

Reference is now made to FIG. 5 wherein the new and improved bellows construction is applied to an expansion joint comprising a housing and a stem slidably mounted within the housing, generally indicated by reference numerals 200, 201, respectively.

The housing 200 is of general circular or pipe configuration having a flange 202 of one end. The housing 200 is axially hollow with a plurality of

guide stop

203, 204 and 205 provided in inside wall 206. A part 207 is located in flange 202 to provide communication with hollow interior or chamber'208. A bellows adapter 210 provided with an axial orifice 211 is fastened to one end of housing 200 by means of bolts 212.

Stem 201 comprises a flange 213 from which projects a large neck 214. An axial passageway 215 extends the length of the neck and flange. Externally neck 214 is provided with a plurality of

circular steps

216, 217, 218 and 219. Piston 201 is slidably mounted in axial orifice 211 so as to extend into chamber 208.

The new and improved bellows comprises a plurality of

spacing collars

221, 222, 223 and a series of sections of

convoluted bellows

224, 225, 226, 227.

A lower bellows adapter 220 is held against circular step 216 by means of a nut 228 rotatively connected to the end of neck 214. Bellows section 224 is fastened on one end to lower bellows adapter 220 and on the other end to spacing collar 221. Bellows section 225 is fastened on one end to spacing collar 221 and on the other end to spacing collar 222. Bellows section 226 is fastened one end to spacing collar 222 and on the other end to spacing collar 223. Bellows section 227 is fastened on one end to spacing collar 223 and on the other end to flange or upper bellows adapter 210. It will be noted that the bellows sections and spacing collars surround neck 214 and resiliently attach neck 214 to flange 210.

It will be further noted that fluid in chamber 208 may flow around the outside surfaces of the collars and bellow sections and be trapped by flange 210.

Each bellows

section

224, 225, 226, 227 has the same means diameter as indicated by dot and dash line 230.

Throughout the specification and claims mean diameter is synonymous with piston diameter or effective area; terms used in the art.

The pressurized fluid acting on the outside surfaces of the, respective, bellows sections and collars will produce an equal pressure on each convolution. The relative position of the stem 201 to the housing 200 will expand or contract each convolution of each bellows section uniformly because the bellows are in sections instead of in one long piece.

Steps

217, 218, 219 in cooperation respectively, with

guide steps

203, 204, 205, limits the relative movement, respectively, of spacing

collars

221, 222, 223 and thereby, the degree that the convolutions of each bellows 224, 225, 226, 227 may be extended or contracted. Since the convolutions are prevented from exceeding their elastic limit or modulus of elasticity, the pressure of the fluid will not cause the convolutions to rupture.

Having shown and described preferred embodiments of the present invention, by way of example, it should be realized that structural changes could be made and other examples given without departing from either the spirit or scope of this invention.

What we claim is:

1. A bellows assembly comprising an upper bellows adapter, a bellows of a preselected number of convolutions, a spacing collar, means fastening the convolution on one end of said preselected number of convolutions to said upper bellows adapter, and a second means fastening the convolution on the opposite end of said preselected number of convolutions to said spacing collar, a second bellows of a preselected number of convolutions, a lower bellows adapter, a third means fastening the convolutions on end of said preselected number of convolutions of saidsecond bellows to said spacing collar, and a fourth means fastening the convolution on the opposite end of said preselected number of convolutions of said second bellows to said lower bellows adapter, said bellows of a preselected number of convolutions, and said second bellows of a preselected number of convolutions being equivalent in number of convolutions to a single bellows having the necessary number of convolutions to provide the required motion length, and a preselected number of stop means, one for each spacing collar, to limit the axial movement of the spacing collar in one direction.

2. A bellows assembly comprising an upper bellows adapter, a bellows of a preselected number of convolutions, an upper spacing collar, the end convolution on one end of said bellows being fastened to said upper bellows adapter, the end convolution on the other end of said bellows being fastened to said upper spacing collar, a second bellows of a preselected number of convolutions, a lower spacing collar, the end convolution on one end of said second bellows being fastened to said upper spacing collar, the end convolution on the other end of said second bellows being fastened to said lower spacing collar, a third bellows of a preselected number of convolutions, a lower bellows adapter the end convolution on one end of said third bellows being fastened to said lower spacing collar, the end convolution on the other end of said third bellows being fastened to said lower bellows adapter to provide a sectionalized bellows adapted to have each convolution of all bellows react uniformly, said bellows of a preselected number of convolutions, said second bellows of a preselected number of convolutions, and said third bellows of a preselected number of convolutions, being equivalent in number of convolutions to a single bellows having the necessary number of convolutions to provide the required motion length, and a preselected number of stop means, one for each spacing collar, to limit the axial movement of the spacing collar in one direction.

3. The bellows assembly as defined in claim 1 wherein, said bellows and said second bellows are of equally effective fluid pressure area.

4. The bellows assembly as defined in claim 1 wherein, said bellows and said second bellows are of unequally effective fluid pressure area.

5. A bellows assembly consisting of a housing having an interior wall provided with a plurality of stops, and a well having an inlet and an outlet, a stem provided with a valve plug as having a plurality of equal and opposite steps, said stem having an upper bellows adapter, and means for mounting said stem within said housing for relative movement with said housing, to move said valve plug into and out of said well, a lower bellows adapter, having an annular recess, surrounding said stem and fixed to said housing, and a plurality of bellow sections, each bellow section consisting of a preselected number of convolutions, a plurality of spacing collars, one less in number than the plurality of bellow sections, means fastening the spacing collars between each two of said plurality of bellow sections, means fastening the end of one of said plurality of bellow sections to said upper bellow adapter, and means fastening the end of one of said plurality of bellow sections-to said lower bellows adapter, said plurality of bellow sections and said plurality of spacing collars surrounding said stem, each of said plurality of spacing collars engageable disengageably with a stop in said housing and an oppositely located step in said stem, through the relative movement of said stem with said housing, said plurality of bellows sections being equivalent in said preselected number of convolutions to a single bellows having the necessary number of convolutions to provide the required motion length, said stops limiting the axial movement of said spacing collars in one axial direction, said steps limiting the axial movement of said spacing collars in an opposing axial direction.

6. A bellows assembly consisting of a housing having an interior wall provided with a plurality of stops, and a well having an inlet and an outlet, a stem provided with an upper bellows adapter on one end and a valve plug on the other end, means for mounting said stern within said housing for relative movement with said housing to move said valve plug into and out of said well, a lower bellows adapter, having an annular recess surrounding said stem, fixed to said interior wall, and a plurality of bellow sections, each bellow section consisting of a preselected number of convolutions, a plurality of spacing collars one less in number than the plurality of bellow sections, means fastening the spacing collars beteen each two of said plurality of bellow sections, means fastening the end of one of said plurality of bellow sections to said upper bellows adapter, and means fastening the end of one of said plurality of bellow sections to said lower bellows adapter, said plurality of bellow sections and said plurality of spacing collars surrounding said stem, each of said plurality of spacing collars engageable and disengageable with a stop in said interior wall through the relative movement of said stem with said housing, said plurality of bellow sections being equivalent in said preselected number of convolutions to a single bellows having the necessary number of convolutions to provide the required motion length, said stops limiting the axial movement of said spacing collars in one axial direction, said steps limiting the axial movement of said spacing collars in an opposite axial direction.

7. The bellows assembly as defined in claim 6 wherein, said bellow sections are of equally effective fluid pressure area.

8. The bellows assembly as defined in claim 6 wherein, said bellow sections are of progressively smaller effective fluid pressure area so as to resiliently urge said upper bellows adapter away from said lower bellows adapter.

9. A bellows assembly consisting of a housing having an interior wall forming a chamber, a port in communication with said chamber, an upper bellows adapter having an axial orifice means fastening said upper bellows adapter to said housing, a plurality of stops located in said interior wall, a stem having a flange on one end and a long neck provided with a plurality of steps projecting from said flange, said long neck passing through said axial orifice into said chamber, an axial passageway in said stem in communication with said chamber, a lower bellows adapter, means fastening said lower bellow's adapter to an end of said stem, and a plurality of bellow sections,'each bellow section consisting of a preselected number of convolutions, a plurality of spacing collars, one less in number than the plurality of bellow sections, means fastening the spacing collars between each two of said plurality of bellow sections, means fas tening the end of one of said plurality of bellow sections to said lower bellows adapter, said plurality of bellow sections and said plurality of spacing collars surrounding said long neck of said stem, each of said plurality of spacing collars engageable and disengageable with a stop in said housing and an oppositely located cooperating step in the long neck of the stem, through the relative movement of said stem with said housing, said bellow sections, said spacing collars, said lower bellows adapter and said upper bellows adapter resiliently mounting said stem to said housing, said plurality of bellow sections being equivalent in said preselected number of convolutions to a single bellows having the necessary number of convolutions to provide the required motion length, said stops limiting the axial movment of said spacing collars in one axial direction, said step limiting the axial movement of said spacing collars in an opposite axial direction.

Claims

1. A bellows assembly comprising an upper bellows adapter, a bellows of a preselected number of convolutions, a spacing collar, means fastening the convolution on one end of said preselected number of convolutions to said upper bellows adapter, and a second means fastening the convolution on the opposite end of said preselected number of convolutions to said spacing collar, a second bellows of a preselected number of convolutions, a lower bellows adapter, a third means fastening the convolutions on end of said preselected number of convolutions of said second bellows to said spacing collar, and a fourth means fastening the convolution on the opposite end of said preselected number of convOlutions of said second bellows to said lower bellows adapter, said bellows of a preselected number of convolutions, and said second bellows of a preselected number of convolutions being equivalent in number of convolutions to a single bellows having the necessary number of convolutions to provide the required motion length, and a preselected number of stop means, one for each spacing collar, to limit the axial movement of the sapcing collar in one direction.

5. A bellows assembly consisting of a housing having an interior wall provided with a plurality of stops, and a well having an inlet and an outlet, a stem provided with a valve plug as having a plurality of equal and opposite steps, said stem having an upper bellows adapter, and means for mounting said stem within said housing for relative movement with said housing, to move said valve plug into and out of said well, a lower bellows adapter, having an annular recess, surrounding said stem and fixed to said housing, and a plurality of bellow sections, each bellow section consisting of a preselected number of convolutions, a plurality of spacing collars, one less in number than the plurality of bellow sections, means fastening the spacing collars between each two of said plurality of bellow sections, means fastening the end of one of said plurality of bellow sections to said upper bellow adapter, and means fastening the end of one of said plurality of bellow sections to said lower bellows adapter, said plurality of bellow sections and said plurality of spacing collars surrounding said stem, each of said plurality of spacing collars engageable and disengageable with a stop in said housing and an oppositely located step on said stem, through the relative movement of said stem with said housing, said plurality of bellows sections being equivalent in said preselected number of convolutions to a single bellows having the necessary number of convolutions to provide the required motion length, said stops limiting the axial movement of said spacing collars in one axial direction, said steps limiting the axial movement of said spacing collars in an opposite axial direction.

6. A bellows assembly consisting of a housing having an interior wall provided with a plurality of stops, and a well having an inlet and an outlet, a stem provided with an upper bellows adapter on one end and a valve plug on the other end, means for mounting said stem within said housing for relative movement with said housing to move said valve plug into and out of said well, a lower bellows adapter, having an annular recess surrounding said stem, fixed to said interior wall, and a plurality of bellow sections, each bellow section consisting of a preselected number of convolutions, a plurality of spacing collars one less in number than the plurality of bellow sections, means fastening the spacing collars between each two of said plurality of bellow sections, means fastening the end of one of said plurality of bellow sections to said upper bellows adapter, and means fastening the end of one of said plurality of bellow sections to said lower bellows adapter, said plurality of bellow sections and said plurality of spacing collars surrounding said stem, each of said plurality of spacing collars engageable and disengageable with a stop in said interior wall through the relative movement of said stem with said housing, said plurality of bellow sections being equivalent in said preselected number of convolutions to a single bellows having the necessary number of convolutions to provide the required motion length, said stops limiting the axial movement of said spacing collars in one axial direction, said steps limiting the axial movement of said spacing collars in an opposite axial direction.

9. A bellows assembly consisting of a housing having an interior wall forming a chamber, a port in communication with said chamber, an upper bellows adapter having an axial orifice means fastening said upper bellows adapter to said housing, a plurality of stops located in said interior wall, a stem having a flange on one end and a long neck provided with a plurality of steps projecting from said flange, said long neck passing through said axial orifice into said chamber, an axial passageway in said stem in communication with said chamber, a lower bellows adapter, means fastening said lower bellows adapter to an end of said stem, and a plurality of bellow sections, each bellow section consisting of a preselected number of convolutions, a plurality of spacing collars, one less in number than the plurality of bellow sections, means fastening the spacing collars between each two of said plurality of bellow sections, means fastening the end of one of said plurality of bellow sections to said lower bellows adapter, said plurality of bellow sections and said plurality of spacing collars surrounding said long neck of said stem, each of said plurality of spacing collars engageable and disengageable with a stop in said housing and an oppositely located cooperating step in the long neck of the stem, through the relative movement of said stem with said housing, said bellow sections, said spacing collars, said lower bellows adapter and said upper bellows adapter resiliently mounting said stem to said housing, said plurality of bellow sections being equivalent in said preselected number of convolutions to a single bellows having the necessary number of convolutions to provide the required motion length, said stops limiting the axial movement of said spacing collars in one axial direction, said steps limiting the axial movement of said spacing collars in an opposite axial direction.