US3585905A

US3585905A - Modulator diaphragm and method of assembly

Info

Publication number: US3585905A
Application number: US833567A
Authority: US
Inventors: Stuart A Mason; Ben L Ehlin
Original assignee: Casco Products Corp
Current assignee: Casco Products Corp
Priority date: 1969-06-16
Filing date: 1969-06-16
Publication date: 1971-06-22
Anticipated expiration: 1988-06-22

Abstract

A vacuum modulator is disclosed having a peripherally tabbed diaphragm leading through and externally of folded clamping flanges to provide a visible cue of the registry of the diaphragm relative to the clamping flanges.

Description

United States Patent 1 1 3,585,905

721 Inventors StuartAJHason 2,335,276 11/1943 Heintz 92/99 nria e mcom; 2,738,808 3/1956 HartzelletaL. 92/99x Ben L. Ehlin, Brooklyn, N.Y. 2,840,339 6/1958 Price 92/103 X [21] App]. No. 833,567 2,985,196 5/1961 Brunner 92/99 X [22] Filed June 16, 1969 3,081,793 3/1963 Flatt et al.... 92/100 X [45] Patented June 22,1971 3,151,568 10/1964 Hood et al.. 92/100 X [73] Assignee Casco Products Corporation 3,208,721 9/1965 Mcl-lugh 92/103 X Bridgeport, Conn. 3,283,670 1 111966 Taplin 92/99 Primary Examiner-Edgar W. Geoghegan s41 MODULATOR DIAPHRAGM AND METHOD or Emmi'wrilrwm Cohen ASSEMBLY Anarneys-E. Mannlng Giles, J. Patrick Cagney, Peter S. 3 Claims, 5 Drawing Lucyshyn and Richard G. Kinney [521 11.8. c1. 92/100 511 1111.01 F16] 3/00 501 FieldoiSeai-ch 92/100, 103,103 5, 103 M, 98, 99,101, 93, 89, 47, 48; 73/410 ABSTRACT: A vacuum modulator is disclosed having a [56] new? Cited peripherally tabbed diaphragm leading through and externally UNITED STATES PATENTS of folded clamping flanges to provide a visible cue of the regis- 2,306,768 12/1942 Wile 92/100 X try of the diaphragm relative to the clamping flanges.

MODULATOR DIAPHRAGM AND METHOD OF ASSEMBLY This invention relates to pressure responsive diaphragmtype linear actuators and more particularly is concerned with an improved diaphragm construction for a transmission modulator or similar device.

In a typical vacuum modulator such as is utilized in an automatic transmission system of an automobile, a differential pressure capsule is comprised of a pair of mating rigid casing shells spanned by a flexibly distortable internal diaphragm to define separate pressure chambers therein, each exposed to different pressure conditions. One chamber is subjected to engine manifold vacuum. A center plate structure is associated with the diaphragm and is arranged to engage an external push rod leading through the other chamber to control a throttle valve in accordance with changes in manifold pressure. It is required that the diaphragm provide a permanent fluidtight seal between the chambers and it has been the practice to provide one of the casings with a circumambient seal rim portion in the form of an outwardly directed annular flange and to provide the other casing with a mechanically flared end for defining a confronting annular flange and a marginal lip which may be crimped about the first flange in a reverse bend configuration. A generally U-shaped groove is defined between the first flange and the crimped flange, with the periphery of the diaphragm being disposed in the U-groove.

In the prior art practice, the diaphragm is completely masked by the clamping flanges so that there is uncertainty as to whether the diaphragm has been accurately registered and secured along its entire periphery. It has not been practical to utilize oversize diaphragms as the large diameter marginal portions, when folded over to occupy a region of smaller diameter, tend to bunch and thereby interfere with the uniformity of the clamping and sealing relationships that are desired.

Where a bunching condition develops, there is the further problem that cuttingor tearing of the diaphragm may occur leading to actual diaphragm pullout.

In accordance with the present invention, a diaphragm construction is provided which solves these difficulties and, in ad dition, provides a reliable visible cue in the final assembly which pennits the assembler, tester and user to see that the diaphragm is in properly registered relationship to the clamping rims. If the diaphragm is offcenter, improper diaphragm assembly is indicated.

Thus, in accordance with this invention, there is provided a differential pressure capsule having a flexibly distortable internal diaphragm spanning an intermediate region thereof to define separate pressure chambers therein, the capsule being comprised of mating rigid casing shells having confronting circumambient clamping rim portions cooperable to define a circumambient groove for receiving and gripping a circumambient portion of the diaphragm in edge-sealed relation, the diaphragm having integral edge tabs spaced along the periphery of the diaphragm and projecting externally of the groove to provide visible indication of the registry of the diaphragm relative to the clamping rim portions.

The embodiment of the invention illustrated herein is a vacuum modulator having a diaphragm of laminar construction comprised of a fabric layer covered with an elastomer coating, the diaphragm having a configuration to accommodate the required travel and the casing shells having confronting clamping flanges, one flange having a marginal lip to be reverse bent about the other by a mechanical crimping operation to define a U groove.

The edge of the diaphragm has a reverse bend configuration like that of the U-groove resulting in the larger diameter portion of the diaphragm extending inwardly through a smaller diameter region of the groove. The spaced tab portions on the edge of the diaphragm project externally of the U-shaped groove without objectionable bunching.

Other features and advantages of the invention will be apparent from the following description and claims and are illustrated in the accompanying drawings which show structure embodying preferred features of the present invention and the principles thereof, and what is now considered to be the best mode in which to apply these principles.

In the accompanying drawings forming a part of the specification and in which like numerals are employed to designate like parts throughout the same:

FIG. I is a side elevational view of a vacuum modulator incorporating a diaphragm construction in accordance with this invention, the view being shown partly in section to facilitate disclosure;

FIG. 2 is a fragmentary end view of the modulator of FIG. 1 with portions thereof broken away and sectioned;

FIG. 3 is a fragmentary plan view of the diaphragm prior to assembly;

FIG. 4 is an enlarged fragmentary sectional view through the clamping and seal regions of the device and is taken approximately as indicated on the line 4-4 of FIG. 2; and

FIG. 5 is a diagrammatic view illustrating the method of assembly of the modulator.

Referring now to the drawings and particularly to FIG. 1, a fluid actuated control unit, designated generally at 10, is shown as a vacuum modulator for purposes of illustrative disclosure. The modulator consists of a differential capsule 11 having a flexibly distortable internal diaphragm assembly 12 spanning an intennediate region of the capsule to define

separate pressure chambers

13 and 14 therein. The capsule is defined by a pair of mating rigid shells l5 and 16 which have clamping n'm structures cooperable to grip a diaphragm in sealing relationship therebetween.

The diaphragm assembly 12 is shown as including a flexible diaphragm element 17 encircling a floating carrier 18 which is equipped with

reinforcement plates

19, 20 for engagement with opposite faces of the diaphragm. The carrier 18 is shown equipped with fastener structure 18F to secure the parts of the diaphragm assembly. The plate 20 serves as a spring seat for a load spring 21 located in the shell 15. The shell 15 is provided with a connection fitting 15F to establish communication between the chamber 13 and the engine manifold so that manifold vacuum may act to control the position of the diaphragm 17. The shell 16 is provided with a threaded bushing 16T for connection to the transmission system. An external push rod 22 leads through the threaded bushing MT and is acted upon by the fluid pressure in the transmission system to load the push rod against the carrier. Thus changes in manifold vacuum act on the modulator diaphragm to effect positioning of the push rod 22 and thereby control the throttle valve.

In the illustrated embodiment, the flexibly distortable diaphragm element 17 may be installed under maximum deflection or may have a slightly dished or corrugated shape in accordance with the required travel stroke for the diaphragm. For this particular application, the diaphragm 17 preferably consists of a nylon fabric sheet covered with an elastomer coating. Typical elastomer materials suitable for this purpose include Buna N rubber or fluorosilicone rubber compounds.

In the illustrated embodiment, the casing shells are shown as metal stampings, the shell 15 having a clamping rim 23 in the form of an outwardly directed annular flange and the shell 16, as initially formed, having a mechanically flared end providing a clamping rim 24 comprised of a confronting flange 24 and a marginal lip 25 (see FIG. 5).

As finally assembled (see FIG. 4), the lip 25 has a reverse bend configuration and the diaphragm edge is gripped in a U configuration to occupy the U-shaped groove that is defined between the

clamping portions

23, 24 and 25.

The diaphragm has integral edge tabs l7T spaced about its periphery, the tabs having a base region 178 normally located at the position indicated in FIG. 4 to minimize bunching due to diameter differences associated with the folded configuration. The tabs l7T project externally of the groove and along the sidewall of the shell 15 to present a visible cue of the registry of the diaphragm relative to the clamping portions. It is apparent from'the drawings of the preferred embodiment that the edge tabs 117T constitute an annular array of uniformly spaced indicators space along the entire periphery to indicate registry of the diaphragm along its entire periphery. As is apparent in FIGS. 1 and 2 the tab array in the final assembly collectively and uniformly covers a major perimetral portion of the visible surface of the shell 15 at the region of such surface which is adjacent the U-shaped groove. Accurate registry is important for assuring adequate sealing and for avoiding bunching.

The assembly of the modulator is best explained in relation to FIG. 5 wherein the casing shell 16 is shown with its flared end facing up and with an external assembly pin 26 projecting through the threaded bushing 16'! and engaging the carrier 18 to support the diaphragm assembly 12 so that the diaphragm 17 is lightly above the marginal lip 25 and has its edge projecting outwardly of the lip. This diaphragm position corresponds to the maximum deflection condition encountered during operation of the modulator. The casing shell 15 and coil spring 21 are lowered onto the shell 16 and spring seat 20, respectively, while the diaphragm position is maintained. The lip 25 then is crimped into reverse bend configuration about the flange 23 to complete the assembly. The diaphragm 17 will then assume the relaxed configuration in which it is shown in FIG. 1 and can accommodate a predetermined travel stroke without stretching.

Thus, while preferred constructional features of the invention are embodied in the structure illustrated herein, it is to be understood that changes and variations may be made by those skilled in the art without departing from the spirit and scope of the appended claims.

The embodiments of the invention in which an exclusive property of privilege we claim are as follows:

l. in a differential pressure capsule having a flexibly distortable internal diaphragm spanning an intermediate region thereof to define separate pressure chambers therein, the capsule being comprised of first and second mating rigid casing shells having confronting circumambient clamping rim portions cooperable to define a circumambient groove for receiving and gripping a circumambient portion of the diaphragm in edge-sealed relation, the first shell rim portions having an annular outwardly directed flange and the second having an annular flange presenting an opposed flange portion and a reverse bend lip portion defining a circumambient U- shaped groove for the edge of the diaphragm, the improvement comprising an annular array of uniformly spaced integral diaphragm edge tabs spaced along the entire periphery of the diaphragm, said tabs projecting externally of the groove to collectively and uniformly cover major perimetral portion of the surface on said first shell rim portion immediately above said groove to provide visible indication of the registry of the diaphragm relative to the clamping rim portions.

2. In a method of assembling a differential pressure capsule that includes a flexibly distortable diaphragm and a pair of rigid casing shells having confronting circumambient rim portions for gripping the diaphragm in sealing relation about its periphery, the steps for forming one of the shells with an annular peripheral flange of predetermined diameter forming the other shell with a confronting flange for the first flange and with a marginal lip, locating a diaphragm that has an annular array of uniformly spaced peripheral tab portions in position to span the confronting flange with the tab portions of the diaphragm projecting outwardly of the lip, seating the flange of the first-named shell against the diaphragm portion that spans the confronting flange, and bending the lip into reverse bend configuration about the first-named flange for folding and sealing the edge of the diaphragm into a U-configuration wherein the tab portions project along an externally visible region of the first-named shell and uniformly cover a substantial portion of said externally visible region.

3. A method in accordance with claim 2 and including locating and holding the diaphragm in a maximum travel configuration during seating of the flange of the first-named shell and during bending of said lip.

Claims

1. In a differential pressure capsule having a flexibly distortable internal diaphragm spanning an intermediate region thereof to define separate pressure chambers therein, the capsule being comprised of first and second mating rigid casing shells having confronting circumambient clamping rim portions cooperable to define a circumambient groove for receiving and gripping a circumambient portion of the diaphragm in edge-sealed relation, the first shell rim portions having an annular outwardly directed flange and the second having an annular flange presenting an opposed flange portion and a reverse bend lip portion defining a circumambient U-shaped groove for the edge of the diaphragm, the improvement comprising an annular array of uniformly spaced integral diaphragm edge tabs spaced along the entire periphery of the diaphragm, saId tabs projecting externally of the groove to collectively and uniformly cover major perimetral portion of the surface on said first shell rim portion immediately above said groove to provide visible indication of the registry of the diaphragm relative to the clamping rim portions.