CA1178080A - Diaphragm - Google Patents
DiaphragmInfo
- Publication number
- CA1178080A CA1178080A CA000400039A CA400039A CA1178080A CA 1178080 A CA1178080 A CA 1178080A CA 000400039 A CA000400039 A CA 000400039A CA 400039 A CA400039 A CA 400039A CA 1178080 A CA1178080 A CA 1178080A
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- Prior art keywords
- diaphragm
- wrinkles
- wrinkle
- plane
- axes
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
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- Diaphragms And Bellows (AREA)
Abstract
ABSTRACT
A diaphragm having a pattern of wrinkles adapted so that the diaphragm is both radially and tangentially expandable with respect to a reference point in that central portion.
A diaphragm having a pattern of wrinkles adapted so that the diaphragm is both radially and tangentially expandable with respect to a reference point in that central portion.
Description
1 1 78~80 BACKGROU~D OF THE DISCLOSURE
The pre~ent ~nvention i~ in the field of tran~ducer~, and more particularly, to tran3ducer~
10 having a deformable diaphragm sensing elemsnt.
There are many form~ of prior art transducers which incorporate a diaphragm member as the sensing ele-~ent. Such sensing elements are also used in linear variable differential transformer~ (LVDT'6) and o~her 15 form~ of motion ~ransducers. In addition, certain forms of prior art ~train gage~ use such diaphragm3. In substantially all of ~he~e-application~, ~he diaphragm ~ensing element i8 generally a relatively ~mooth, thin deformable member, often stretc~ed between edge-located 20 support points. While ~uch diaphragms are generally effective in their intended uses, they are often the performance-limiting elements in the operation of ~ensors over temperature ranges, and also in sensitivity for such sensor3. To achieve optimal performance, the 25 diaphragm sensing element mu~t be relatively stable dimensionally over temperature as well a~ provide a uniform sensitivity. In order to provide high sensitivity, the diaphragm must be very sensitive to deforming orces.
Generally, the prior art stretched diaphragms (such ~ thin sheet~ of stainless steel on the order of .0002 inches thick) are relatively limited in both sen-sitivity and stability.
The pre~ent ~nvention i~ in the field of tran~ducer~, and more particularly, to tran3ducer~
10 having a deformable diaphragm sensing elemsnt.
There are many form~ of prior art transducers which incorporate a diaphragm member as the sensing ele-~ent. Such sensing elements are also used in linear variable differential transformer~ (LVDT'6) and o~her 15 form~ of motion ~ransducers. In addition, certain forms of prior art ~train gage~ use such diaphragm3. In substantially all of ~he~e-application~, ~he diaphragm ~ensing element i8 generally a relatively ~mooth, thin deformable member, often stretc~ed between edge-located 20 support points. While ~uch diaphragms are generally effective in their intended uses, they are often the performance-limiting elements in the operation of ~ensors over temperature ranges, and also in sensitivity for such sensor3. To achieve optimal performance, the 25 diaphragm sensing element mu~t be relatively stable dimensionally over temperature as well a~ provide a uniform sensitivity. In order to provide high sensitivity, the diaphragm must be very sensitive to deforming orces.
Generally, the prior art stretched diaphragms (such ~ thin sheet~ of stainless steel on the order of .0002 inches thick) are relatively limited in both sen-sitivity and stability.
-2-Accordingly, it is an ob~ect of the present invention to provide an improved diaphragm sen~ing çle-ment for a transducer which i8 relatively ~table while providing high sensitivity.
It i8 another object to provide an improved diaphragm which includes a portion which i~ resiliently displaceable along an axi~ perpendicular to that port~on.
SUMMARY OF THE I~VENTION
_ Briefly, the present invention i8 a diaphragm including a diaphragm member having a pattern of wrinXle~ whereby the diaphragm i8 both radially and tangentially expandable with respect to any reference point in it~ central portion. In one form of the inven-lS tion, the diaphragm member has a nominally planar por- ~
tion and a plurality wrinkle portions extending from at lea~t one side of the planar portion. In alternate forms of the invention, the wrinkle portions may extend from both side~ of the pl~nar portion. Generally, with 20 this configuration, a dimensionally ~table structure i~
provided with high sensitivity to pressure differentials applied acro~s the structure. For example, with a metallic foil diaphragm in accordance with the present invention, and which i8 ~dapted for use in ~ capacitance 25 transducer, the improvzment in ~en~itivity and ~tability is on the order of a factor of ten compared with a capacitive tran~ducer using a conventional planar diaphragm having comparable dimension6.
BRIEF DESCRIPTION OF THE DRAWI~G
The foregoing and other objects of this inven-tion, the variouE features thereof, ~ well as the invention it~elf, may be more fully understood from the following description, when read together wnth the accompanying draw~ngs in which:
.11~78~8V
Fig. 1 shows a plan view of an exemplary diaphragm in accordance with the pre~en~ invention;
Fig. 2A 0hows a cro~6-section of a portion of the diaphragm of Fig. 1~
Fig. 2B shows a cross-section of a portion of a diaphragm having a moderately dense wrinkle pattern;
and Fig. 2C shows a cro6s-section of a portion of a diaphragm having a relatively dense wrinkle pattern;
10 and Figs. 3-13 illustrate alternate embodiment~ of the present inventlon.
DESCRIPTION OF THE PREFERRED EMBODIMENT
Figs. 1 and 2A ahow a diaphragm element 10 in 15accordance with the present invention. The diaphragm 10 i~ a circular metal foil (such as aluminum) having thickness on the order of .0002 inches. The foil is substantially planar but include~ a plurality of wrinkle portions extending from one side. In Fig. 1, the 20wrinkled portions are indicated by the short lines. In the illuetrated ~mbodiment, the wrinkle portions extend only in a single direction from (i.e. to one ~ide of) the planar portion of the diaphrag~. However, in alter-native embodiments, some of the wrinkled portion~ may 25extend on one side of t~e diaphragm, while others may extend on the other side.
It wtll be understood that in Fig. 1, the wrinkle portions ~re considered to be perturbations from ~ no~inally planar portion. However, in embodiments 30h~ving relatively dense wrinkle patterns, the Nplanar . . .
OBO
1 portion" as referred to herein may not be strictly planar, but rather represents the "base" from which extrema of the wrinkle portions extend. In yet other embodiments, the wrinkle distribution may be so dense that the wrinkle portions may just be described as wrinkles, without reference to a base. By way of example, Fig. 2B shows a cross-section of a diaphragm having a moderately dense wrinkle pattern. The broken line 14 is an exemplary reference line which for illustrative purposes separates the 'Iwrinkle portions'l (above line 14) from the llplanar portionsll (below line 14). In this illustration, the portions below line 14, while not strictly planar, are referred to as 'Iplanar''. As shown in the less dense pattern of Fig. 2A, the "planar portion'l (i.e. below line 14) is closer to being strictly planar. Fig. 2C shows a relatively high density wrinkle pattern. In some forms of the invention, the diaphragm may be slightly lldomedll so that the wrinkle portions extend from a nominally spherical portion of the diaphragm. ~Iowever, in such embodiments, the radius of the dome is relatively large compared with the wrinkle dimensions. Accordingly, the spherical portion is considered to fall within the terminology "planar portion" as used herein.
In the construction of Fig. 1, the wrinkled portions in diaphragm 10 are randomly oriented over the surface of the diaphragm. Fig. 2 shows a cross-section of the foil taken through one of the wrinkled portions of the diaphragm 10.
By way of example, in use, the diaphragm 10 may be edge supported under radial tension in a capacitive pressure sensor assembly. In such a sensor, the central portion of the diaphragm 10 may be relatively 0~0 easily displaced in a direction perpendicular to the plane of the supported edge of diaphragm 10 in re6ponee to changes in the pressure differential acroes the diaphragm. With the ~tructure of the preBent invention~
S that d~splacement of the central portion diaphragm 10 i~
a highly repeatable function of the pre~sure differen-tial. Moreover, this repeatability is relatively constant over temperature~ Overall, the diaphragm 10 is a factor of ten better in sensitivity and stability 10 (over both time and temperature) compared wnth a similar thickness planar (conventional) di aphraqm .
Each of the wrinkle portion~ in the diaphragm 10 iB stra1ght and extends along an associated principal axis in the plane of the planar portion. In alternative 15embodiments, at lea~t ~ome of the wrinkled portions may be curved and extend along corre6pondingly curved reference lines in the plane of the planar e~ement~
The diaphragm 10 of Fig. 1 may be formed by the following eequence of step6. First, a planar 20elastic member, such as a rubber sheet, iB ~tretched in two perpendicular directions 80 that the stretched elastic member lies in a plane. Then, a relatively thin metal foil i~ frictionally coupled to the surface of the etretched elastic member ~o that the foil li~s flat 25against the ~tretched elastic member. The foil may be, for example, lightly cemented to the ~urface of the elastic member, or alternatively, may be held against that stretched elastic member by means of a relatively high gas pre6sure. The clamping on the ela~tic member 30is then released 80 that that elastic member may return to its unstretched state. A~ the elastic member returns to th~t state, the fr~ctional coupling between the foil and that elastic member causes the foil to wrinkle in A
low energy pattern ~o that the foil then ha~ a relati-11~780~30-- 6 --1 vely planar por-tion and a plurality of wrinkle portions. The foil member is then separated from the diaphragm member (for example, by removiny the relatively high air pressure from the side holding it against the diaphragm) and the resultant wrinkled foil may be used as a sensing element for a transducer.
In accordance with a second method of forming a diaphragm according to the invention, a relatively thin metallic foil is positioned in a sandwich configuration between two edge supported planar elastic members (such as rubber sheets) with a pressure Pl outside the sandwich and adjacent to one of the sheets, a pressure P2 between the two sheets, and a pressure P3 outside the sandwich and adjacent to the other sheet.
Initially, Pl equals P2 and both Pl and P2 exceed P3. Then the pressures are adjusted so that Pl exceed P2 which in turn exceeds P3 resulting in a stretching of the sandwich. The pressures are then adjusted so that Pl equals P3 where both Pl and P3 exceed P2. This step returns the sheets to their original unstretched position. As the sheets contract, the frictional contact with the foil (caused by the relatively low pressure P2 during this step) causes the foil to wrinkle. As a final step, the pressures Pl, P2, and P3 are equalized, the sheets are separatea and the foil diaphragm is removed.
It will be understood that both of the above forming processes result in relatively low energy configurations of the foil. Consequently, the diaphragms of the present invention are well suited for use in capacitive pressure sensors, or other prior art diaphragm capacitance pressure sensors, which utilize edge supported diaphragms based on displacement of the central portions thereof.
llt7~8C) In various other embodiments, the diaphragm may be electrically non-conductive, when ~or example the position of the central portion may be detec-ted op-tically. In o-ther forms, the diaphragm may be non-conductive, but include a conductive region on one surface, such as may be formed by a deposited conductive film. In the latter form of the invention, a portion of the conductive film extends to the periphery of the diaphragm for permitting electrical contact to external measuring instrumentation. In these and other forms, the present invention provides a "soft" diaphragm which is useful in many devices. For example, the present invention might be used to replace the conventional diaphragms in certain prior art strain gages and switches. Alternatively, the diaphragm might be used to separate two fluids where it is important that -pressure differentials be transmitted across the interfluid boundaries.
Figs. 3 6 show alternate forms for the present invent-ion. In Fig. 3, a portion of a diaphragm similar to diaphragm 10 is shown, wherein the wrinkled portions are curved and extend along correspondingly curved reference line segments in-the plane of the planar portion of diaphragm 10.
Fig. 4 shows a limited region of a diaphragm having a pattern where straight wrinkle portions are each aligned sub-stantially with one of three axes in the plane of the planar portion, where those axes are 60 dégrees offset from each other.
This pattern results in a "snowshoe" pattern having a plurality of equilateral triangular and hexagonal portions of the~plane pattern defined by the wrinkle portions.
11~7~08~
Fig. 5 shows a l~mited portion of another embodiment of a diaphr~gm, where ~he straight wrinkle r portions are aligned with one of ~wo axes in the plane of the planar portion, where those two axe~ are 90 5 degrees offset from each other. The resultant pattern include~ a plurality of square areas in ~he plane portion as defined by the wrinkle portions.
Fig. 6 ~hows an embodiment of the present invention where the diaphragm includes a plurality of 10 concentric zig-zag ring patterns formed by the wrinkle portions. In the embodiment of Fig. 6, ~he zig-zag pat-terns are discontinuous, i.e. each ~ig-zag ring include~
a pair of joined straight line wrinkle segments which are not connected, or ~oined, to the ~djacent pairs $n 15 the ring~ In other embodiments, even the pair~ may be non-connected.
Figs. 7-13 ~how plan view em~odiments of diaphragms having alternate wrinkle patterns in keeping with the pre~ent invention. In all of theze figures, 20the dlaphragms are generally denoted by reference numeral 10, and a portion of the periphery of each diaphragm i8 denoted by reference numeral 12.
The wrinkle pattern of the diaphragms of Figs.
7-10 generally include concentric ~ig-zag ring wTinkle 25 portions which are continuous (i.e. -each zig-zag ring includes relatively short, straight line wrinkle segment~ which are connected at their ends to adjacent straight line wrinkle segments). The diaphragms of Figs. 7 and 10 further include a eet of ~V" shaped or 30 "chevron" wrinkle portions filling in otherwnse blank are~s in the pattern.
The various ring~ of the wrinkle pattern of the diaphragm of Fig. 7 are sub~t~ntially equidistant .. . . . . . . ..
O~O
from adjacent ring~, result~ng ln interior ring angles which ~ncrease from ring-to-ring ~ith their radial distance from the diaphragm cen~er. Alternate in~ernal angles of each of the rings of the wrinXle pattern of 5 the diaphragms of Figs. 8, 9 and 10 are constant (120, 90 and 90 degree~, re~pectively) from ring to ring regardless of their di~tance from the center of the diaphragm. In another form, the diaphragm may include a plurality of ne6ted, radially extending ~ig-~ag wrinkle 10 portions. With all of these configuration~, any region in the wrinkle pattern of diaphragm 10 i B expandable both radially and tangentically with respect to any point on the diaphragm including any point in the central portion of the diaphragm.
Fig~. 12 and 13 ~how limited regions of addi-tional embodiments of the invention having wrinkle pat-terns including linear zig-zag wrinkle portions. In Fig. 12 the wrinkle portions are continuou~ and ln Fig.
13 the wrinkle portions are di~continuous. In the pre-20 ferred form of the configuration~ of Figs. 12 and 13,the angles between the wxinXle peaks (i.e. the black zig-zag line6 shown in Fig. 12) are 90 degree6, the angle~ formed by the trough surfaces between wrinkle peaks are 90 degree~, and the angle6 formed by the peak 25surfaces on either side of wrinkle peaks are 90 degrees.
In other em~odiments, the wrinkled portions may be aligned along differently oriented axe6 in keeping with the present invention.
In all the above embodiment3, t~e wrinkle 30patterns may be generated with a die having a generally planar surface except for perturbations xepresentative of the desired pattern of the wrinkles. Initially, the foil~may be placed ~gain~t that die. m en ~ high 1~'7t~0 pressure gas used to force the foil into the ~hape defined by the die. Alternatively, the foil may be forced against the die by a ru~ber pad driven by the mandrel of ~ hydraul~c press. By way of example, a 1.7 5 inch diameter sensor element in the form of Fig. 10, made of 0.27 mil 303 stainles~ steel, may be made with a die with wrinXle pattern grooves which have a width of 25 mil~ and a depth of 5-10 mils, where the grooves are set apart from each other by 25 mil~. The center por-10 tion of the resultant diaphragm deflects 5 mile for adifferential pressure of .0015 p~i.
In yet other alternative embodiment~, variou~
combinations of the above-defined wrinXle patterns may be used together in the same diaphragm. In all form~, 15 however, it i8 preferred that there be all axe6 in the nominal plane, or surface, of the diaphragm be traversed by at least one wrinkle portion.
The invention may be embodied in other speci-fic forms without departing from the spirit or essential 20 characteristic~ thereof. The present embodiments are therefore to be considered in all respects as illu~tra-tive and not restrictive, the scope of the invention being indicated by the appended claims rather than by the foregoing description, and all changes which come 25 within the meaning and range of equivalency of the claims are therefore intended to be embraced therein.
., .. ~ .. . . .. . .. . . .. .
It i8 another object to provide an improved diaphragm which includes a portion which i~ resiliently displaceable along an axi~ perpendicular to that port~on.
SUMMARY OF THE I~VENTION
_ Briefly, the present invention i8 a diaphragm including a diaphragm member having a pattern of wrinXle~ whereby the diaphragm i8 both radially and tangentially expandable with respect to any reference point in it~ central portion. In one form of the inven-lS tion, the diaphragm member has a nominally planar por- ~
tion and a plurality wrinkle portions extending from at lea~t one side of the planar portion. In alternate forms of the invention, the wrinkle portions may extend from both side~ of the pl~nar portion. Generally, with 20 this configuration, a dimensionally ~table structure i~
provided with high sensitivity to pressure differentials applied acro~s the structure. For example, with a metallic foil diaphragm in accordance with the present invention, and which i8 ~dapted for use in ~ capacitance 25 transducer, the improvzment in ~en~itivity and ~tability is on the order of a factor of ten compared with a capacitive tran~ducer using a conventional planar diaphragm having comparable dimension6.
BRIEF DESCRIPTION OF THE DRAWI~G
The foregoing and other objects of this inven-tion, the variouE features thereof, ~ well as the invention it~elf, may be more fully understood from the following description, when read together wnth the accompanying draw~ngs in which:
.11~78~8V
Fig. 1 shows a plan view of an exemplary diaphragm in accordance with the pre~en~ invention;
Fig. 2A 0hows a cro~6-section of a portion of the diaphragm of Fig. 1~
Fig. 2B shows a cross-section of a portion of a diaphragm having a moderately dense wrinkle pattern;
and Fig. 2C shows a cro6s-section of a portion of a diaphragm having a relatively dense wrinkle pattern;
10 and Figs. 3-13 illustrate alternate embodiment~ of the present inventlon.
DESCRIPTION OF THE PREFERRED EMBODIMENT
Figs. 1 and 2A ahow a diaphragm element 10 in 15accordance with the present invention. The diaphragm 10 i~ a circular metal foil (such as aluminum) having thickness on the order of .0002 inches. The foil is substantially planar but include~ a plurality of wrinkle portions extending from one side. In Fig. 1, the 20wrinkled portions are indicated by the short lines. In the illuetrated ~mbodiment, the wrinkle portions extend only in a single direction from (i.e. to one ~ide of) the planar portion of the diaphrag~. However, in alter-native embodiments, some of the wrinkled portion~ may 25extend on one side of t~e diaphragm, while others may extend on the other side.
It wtll be understood that in Fig. 1, the wrinkle portions ~re considered to be perturbations from ~ no~inally planar portion. However, in embodiments 30h~ving relatively dense wrinkle patterns, the Nplanar . . .
OBO
1 portion" as referred to herein may not be strictly planar, but rather represents the "base" from which extrema of the wrinkle portions extend. In yet other embodiments, the wrinkle distribution may be so dense that the wrinkle portions may just be described as wrinkles, without reference to a base. By way of example, Fig. 2B shows a cross-section of a diaphragm having a moderately dense wrinkle pattern. The broken line 14 is an exemplary reference line which for illustrative purposes separates the 'Iwrinkle portions'l (above line 14) from the llplanar portionsll (below line 14). In this illustration, the portions below line 14, while not strictly planar, are referred to as 'Iplanar''. As shown in the less dense pattern of Fig. 2A, the "planar portion'l (i.e. below line 14) is closer to being strictly planar. Fig. 2C shows a relatively high density wrinkle pattern. In some forms of the invention, the diaphragm may be slightly lldomedll so that the wrinkle portions extend from a nominally spherical portion of the diaphragm. ~Iowever, in such embodiments, the radius of the dome is relatively large compared with the wrinkle dimensions. Accordingly, the spherical portion is considered to fall within the terminology "planar portion" as used herein.
In the construction of Fig. 1, the wrinkled portions in diaphragm 10 are randomly oriented over the surface of the diaphragm. Fig. 2 shows a cross-section of the foil taken through one of the wrinkled portions of the diaphragm 10.
By way of example, in use, the diaphragm 10 may be edge supported under radial tension in a capacitive pressure sensor assembly. In such a sensor, the central portion of the diaphragm 10 may be relatively 0~0 easily displaced in a direction perpendicular to the plane of the supported edge of diaphragm 10 in re6ponee to changes in the pressure differential acroes the diaphragm. With the ~tructure of the preBent invention~
S that d~splacement of the central portion diaphragm 10 i~
a highly repeatable function of the pre~sure differen-tial. Moreover, this repeatability is relatively constant over temperature~ Overall, the diaphragm 10 is a factor of ten better in sensitivity and stability 10 (over both time and temperature) compared wnth a similar thickness planar (conventional) di aphraqm .
Each of the wrinkle portion~ in the diaphragm 10 iB stra1ght and extends along an associated principal axis in the plane of the planar portion. In alternative 15embodiments, at lea~t ~ome of the wrinkled portions may be curved and extend along corre6pondingly curved reference lines in the plane of the planar e~ement~
The diaphragm 10 of Fig. 1 may be formed by the following eequence of step6. First, a planar 20elastic member, such as a rubber sheet, iB ~tretched in two perpendicular directions 80 that the stretched elastic member lies in a plane. Then, a relatively thin metal foil i~ frictionally coupled to the surface of the etretched elastic member ~o that the foil li~s flat 25against the ~tretched elastic member. The foil may be, for example, lightly cemented to the ~urface of the elastic member, or alternatively, may be held against that stretched elastic member by means of a relatively high gas pre6sure. The clamping on the ela~tic member 30is then released 80 that that elastic member may return to its unstretched state. A~ the elastic member returns to th~t state, the fr~ctional coupling between the foil and that elastic member causes the foil to wrinkle in A
low energy pattern ~o that the foil then ha~ a relati-11~780~30-- 6 --1 vely planar por-tion and a plurality of wrinkle portions. The foil member is then separated from the diaphragm member (for example, by removiny the relatively high air pressure from the side holding it against the diaphragm) and the resultant wrinkled foil may be used as a sensing element for a transducer.
In accordance with a second method of forming a diaphragm according to the invention, a relatively thin metallic foil is positioned in a sandwich configuration between two edge supported planar elastic members (such as rubber sheets) with a pressure Pl outside the sandwich and adjacent to one of the sheets, a pressure P2 between the two sheets, and a pressure P3 outside the sandwich and adjacent to the other sheet.
Initially, Pl equals P2 and both Pl and P2 exceed P3. Then the pressures are adjusted so that Pl exceed P2 which in turn exceeds P3 resulting in a stretching of the sandwich. The pressures are then adjusted so that Pl equals P3 where both Pl and P3 exceed P2. This step returns the sheets to their original unstretched position. As the sheets contract, the frictional contact with the foil (caused by the relatively low pressure P2 during this step) causes the foil to wrinkle. As a final step, the pressures Pl, P2, and P3 are equalized, the sheets are separatea and the foil diaphragm is removed.
It will be understood that both of the above forming processes result in relatively low energy configurations of the foil. Consequently, the diaphragms of the present invention are well suited for use in capacitive pressure sensors, or other prior art diaphragm capacitance pressure sensors, which utilize edge supported diaphragms based on displacement of the central portions thereof.
llt7~8C) In various other embodiments, the diaphragm may be electrically non-conductive, when ~or example the position of the central portion may be detec-ted op-tically. In o-ther forms, the diaphragm may be non-conductive, but include a conductive region on one surface, such as may be formed by a deposited conductive film. In the latter form of the invention, a portion of the conductive film extends to the periphery of the diaphragm for permitting electrical contact to external measuring instrumentation. In these and other forms, the present invention provides a "soft" diaphragm which is useful in many devices. For example, the present invention might be used to replace the conventional diaphragms in certain prior art strain gages and switches. Alternatively, the diaphragm might be used to separate two fluids where it is important that -pressure differentials be transmitted across the interfluid boundaries.
Figs. 3 6 show alternate forms for the present invent-ion. In Fig. 3, a portion of a diaphragm similar to diaphragm 10 is shown, wherein the wrinkled portions are curved and extend along correspondingly curved reference line segments in-the plane of the planar portion of diaphragm 10.
Fig. 4 shows a limited region of a diaphragm having a pattern where straight wrinkle portions are each aligned sub-stantially with one of three axes in the plane of the planar portion, where those axes are 60 dégrees offset from each other.
This pattern results in a "snowshoe" pattern having a plurality of equilateral triangular and hexagonal portions of the~plane pattern defined by the wrinkle portions.
11~7~08~
Fig. 5 shows a l~mited portion of another embodiment of a diaphr~gm, where ~he straight wrinkle r portions are aligned with one of ~wo axes in the plane of the planar portion, where those two axe~ are 90 5 degrees offset from each other. The resultant pattern include~ a plurality of square areas in ~he plane portion as defined by the wrinkle portions.
Fig. 6 ~hows an embodiment of the present invention where the diaphragm includes a plurality of 10 concentric zig-zag ring patterns formed by the wrinkle portions. In the embodiment of Fig. 6, ~he zig-zag pat-terns are discontinuous, i.e. each ~ig-zag ring include~
a pair of joined straight line wrinkle segments which are not connected, or ~oined, to the ~djacent pairs $n 15 the ring~ In other embodiments, even the pair~ may be non-connected.
Figs. 7-13 ~how plan view em~odiments of diaphragms having alternate wrinkle patterns in keeping with the pre~ent invention. In all of theze figures, 20the dlaphragms are generally denoted by reference numeral 10, and a portion of the periphery of each diaphragm i8 denoted by reference numeral 12.
The wrinkle pattern of the diaphragms of Figs.
7-10 generally include concentric ~ig-zag ring wTinkle 25 portions which are continuous (i.e. -each zig-zag ring includes relatively short, straight line wrinkle segment~ which are connected at their ends to adjacent straight line wrinkle segments). The diaphragms of Figs. 7 and 10 further include a eet of ~V" shaped or 30 "chevron" wrinkle portions filling in otherwnse blank are~s in the pattern.
The various ring~ of the wrinkle pattern of the diaphragm of Fig. 7 are sub~t~ntially equidistant .. . . . . . . ..
O~O
from adjacent ring~, result~ng ln interior ring angles which ~ncrease from ring-to-ring ~ith their radial distance from the diaphragm cen~er. Alternate in~ernal angles of each of the rings of the wrinXle pattern of 5 the diaphragms of Figs. 8, 9 and 10 are constant (120, 90 and 90 degree~, re~pectively) from ring to ring regardless of their di~tance from the center of the diaphragm. In another form, the diaphragm may include a plurality of ne6ted, radially extending ~ig-~ag wrinkle 10 portions. With all of these configuration~, any region in the wrinkle pattern of diaphragm 10 i B expandable both radially and tangentically with respect to any point on the diaphragm including any point in the central portion of the diaphragm.
Fig~. 12 and 13 ~how limited regions of addi-tional embodiments of the invention having wrinkle pat-terns including linear zig-zag wrinkle portions. In Fig. 12 the wrinkle portions are continuou~ and ln Fig.
13 the wrinkle portions are di~continuous. In the pre-20 ferred form of the configuration~ of Figs. 12 and 13,the angles between the wxinXle peaks (i.e. the black zig-zag line6 shown in Fig. 12) are 90 degree6, the angle~ formed by the trough surfaces between wrinkle peaks are 90 degree~, and the angle6 formed by the peak 25surfaces on either side of wrinkle peaks are 90 degrees.
In other em~odiments, the wrinkled portions may be aligned along differently oriented axe6 in keeping with the present invention.
In all the above embodiment3, t~e wrinkle 30patterns may be generated with a die having a generally planar surface except for perturbations xepresentative of the desired pattern of the wrinkles. Initially, the foil~may be placed ~gain~t that die. m en ~ high 1~'7t~0 pressure gas used to force the foil into the ~hape defined by the die. Alternatively, the foil may be forced against the die by a ru~ber pad driven by the mandrel of ~ hydraul~c press. By way of example, a 1.7 5 inch diameter sensor element in the form of Fig. 10, made of 0.27 mil 303 stainles~ steel, may be made with a die with wrinXle pattern grooves which have a width of 25 mil~ and a depth of 5-10 mils, where the grooves are set apart from each other by 25 mil~. The center por-10 tion of the resultant diaphragm deflects 5 mile for adifferential pressure of .0015 p~i.
In yet other alternative embodiment~, variou~
combinations of the above-defined wrinXle patterns may be used together in the same diaphragm. In all form~, 15 however, it i8 preferred that there be all axe6 in the nominal plane, or surface, of the diaphragm be traversed by at least one wrinkle portion.
The invention may be embodied in other speci-fic forms without departing from the spirit or essential 20 characteristic~ thereof. The present embodiments are therefore to be considered in all respects as illu~tra-tive and not restrictive, the scope of the invention being indicated by the appended claims rather than by the foregoing description, and all changes which come 25 within the meaning and range of equivalency of the claims are therefore intended to be embraced therein.
., .. ~ .. . . .. . .. . . .. .
Claims (26)
1. A diaphragm that flexes in a direction generally normal to said diaphragm in response to a pressure differential across the diaphragm, comprising: a generally thin diaphragm member formed of a structural material that is substantially inelastic, said diaphragm member including a low energy collapse pattern or wrinkles that extend over a substantial portion of the diaphragm, each of said wrinkles being elongated over a short length in any one direction and having an amplitude greater than the thickness of the diaphragm but not projecting substantially from the plane of said diaphragm, said low energy collapse pattern also being such that the angular orientation of said elongated wrinkles varies over said diaphragm member and any axis lying in the plane of said diaphragm intersects at least one wrinkle to thereby re-lieve stresses induced in said diaphragm member by said pressure differential, whereby said diaphragm is both radially and tangen-tially expandable with respect to any reference point in the central portion thereof.
2. A diaphragm according to claim 1 wherein said central portion has an electrically conductive surface.
3. A diaphragm according to claim 1 wherein said diaphragm member includes a peripheral region adapted for supporting said diaphragm so that said central portion is substantially planar.
4. A diaphragm according to claim 1 wherein said wrinkle pattern of diaphragm includes a nominally planar portion and a plurality of wrinkle portions extending from at least one side of said planar portion.
5. A diaphragm according to claim 4 wherein said wrinkle portions extend from both sides of said planar portion.
6. A diaphragm according to claim 1 wherein the principal axes of said wrinkles are aligned substantially with one of three axes on the surface of said central portion, said axes being sixty degrees offset from each other.
7. A diaphragm according to claim 1 wherein the principal axes of said wrinkles are aligned substantially with one of two axes on the surface of the said central portion, said axes being ninety degrees offset from each other.
8. A diaphragm that flexes in a direction generally normal to said diaphragm in response to a pressure differential across the diaphragm, comprising: a generally thin diaphragm member formed of a structural material that is substantially inelastic, said diaphragm member including a low energy collapse pattern of wrink-les that extend over a substantial portion of the diaphragm, each of said wrinkles being elongated over a short length in any one direction and having an amplitude greater than the thickness of the diaphragm but not projecting substantially from the plane of said diaphragm, said low energy collapse pattern being such that the angular orientation of said elongated wrinkles varies over said diaphragm member in a random manner and any axis lying in the plane of said diaphragm intersects at least one wrinkle to thereby relieve stresses induced in said diaphragm member by said pressure differentical, whereby said diaphragm is both radially and tangent-ially expandable with respect to any reference point in the central portion thereof,
9. The diaphragm of claim 8 wherein said wrinkles are dis-continuous.
10. The diaphragm according to claim 9 wherein said wrinkles are each relatively straight.
11. The diaphragm according to claim 9 wherein said wrinkles are each curved.
12. The diaphragm according to claim 11 wherein a portion of said wrinkles are continuous.
13. A diaphragm that flexes in a direction generally normal to said diaphragm in response to a pressure differential across the diaphragm, comprising: a generally thin diaphragm member formed of a structural material that is substantially inelastic, said diaphragm member including a low energy collapse pattern of wrinkles that extend over a substantial portion of the diaphragm, each of said wrinkles being elongated over a short length in any one direction, straight and discontinuous, and having an amplitude greater than the thickness of the diaphragm but not projecting sub-stantially from the plane of said diaphragm, said low energy collapse pattern being such that the angular orientation of said elongated wrinkles varies over said diaphragm member with the principal axes of said wrinkles being aligned generally with one of a plurality axes in the plane of said diaphragm such that any axis lying in the plane intersects at least one wrinkle to thereby relieve stresses induced in said diaphragm member by said pressure differential, whereby said diaphragm is both radially and tangent-ially expandable with respect to any reference point in the central portion thereof.
14. The diaphragm of claim 13 wherein said plurality is three and said axes are offset from one another by sixty degrees.
15. The diaphragm of claim 13 wherein said plurality is two and said axes are offset from one another by ninety degrees.
16. A diaphragm that flexes in a direction generally normal to said diaphragm in response to a pressure differential across the diaphragm, comprising: a generally thin diaphragm member formed of a structural material that is substantially inelastic, said diaphragm member including a low energy collapse pattern of wrinkles that extend over a substantial portion of the diaphragm, each of said wrinkles being elongated over a short length in any one direction and having an amplitude greater than the thickness of the diaphragm but not projecting substantially from the plane of said diaphragm, said low energy collapse pattern being such that the angular orientation of said elongated wrinkles varies over said diaphragm member in a plurality of concentric zig-zag ring patterns where each of said wrinkles is a relatively short, straight portion of one of said rings such that any axis lying in the plane of said diaphragm intersects at least one wrinkle to thereby relieve stresses induced in said diaphragm member by said pressure differential, whereby said diaphragm is both radially and tangentially expandable with respect to any reference point in the central portion thereof.
17. The diaphragm according to claim 16 wherein each of said rings of wrinkles is continuous.
18. The diaphragm according to claim 16 wherein at least some of said ring patterns are formed of wrinkles that are dis-continuous.
19. The diaphragm according to claim 17 wherein interior angles of each of said ring patterns are 90 degrees,
20. The diaphragm according to claim 17 wherein interior angles of each of said ring patterns are 120 degrees.
21. The diaphragm according to claim 17 wherein inter-ring pattern separation is substantially constant.
22. A diaphragm that flexes in a direction generally normal to said diaphragm in response to a pressure differential across the diaphragm, comprising: a generally thin diaphragm member formed of a structural material that is substantially inelastic, said diaphragm member including a low energy collapse pattern of wrinkles that extend over a substantial portion of the diaphragm, each of said wrinkles being elongated over a short length in any one di-rection, straight and having an amplitude greater than the thick-ness of the diaphragm but not projecting substantially from the plane of said diaphragm, said low energy collapse pattern being such that the angular orientation of said elongated wrinkles varies over said diaphragm member with the principal axes of said wrinkles being aligned generally with one of a plurality axes in the plane of said diaphragm such that any axis lying in the plane intersects at least one wrinkle to thereby relieve stresses induced in said diaphragm member by said pressure differential, whereby said dia-phragm is both radially and tangentially expandable with respect to any reference point in the central portion thereof.
23. The diaphragm according to claim 22 wherein groups of said wrinkle are linear to form a wrinkle pattern that is a plur-ality of linear zig-zag patterns.
24. The diaphragm according to claim 23 wherein said linear zig-zag patterns are substantially parallel.
25. The diaphragm according to claim 23 wherein said linear zig-zag patterns are continuous.
26. The diaphragm according to claim 23 wherein said linear zig-zag patterns are discontinuous.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000400039A CA1178080A (en) | 1982-03-31 | 1982-03-31 | Diaphragm |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000400039A CA1178080A (en) | 1982-03-31 | 1982-03-31 | Diaphragm |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1178080A true CA1178080A (en) | 1984-11-20 |
Family
ID=4122462
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000400039A Expired CA1178080A (en) | 1982-03-31 | 1982-03-31 | Diaphragm |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA1178080A (en) |
-
1982
- 1982-03-31 CA CA000400039A patent/CA1178080A/en not_active Expired
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| MKEC | Expiry (correction) | ||
| MKEX | Expiry |