CA1053204A - Snap-acting thermally responsive bimetallic actuators - Google Patents
Snap-acting thermally responsive bimetallic actuatorsInfo
- Publication number
- CA1053204A CA1053204A CA241,645A CA241645A CA1053204A CA 1053204 A CA1053204 A CA 1053204A CA 241645 A CA241645 A CA 241645A CA 1053204 A CA1053204 A CA 1053204A
- Authority
- CA
- Canada
- Prior art keywords
- tongue
- actuator
- free end
- perimeter portion
- outer perimeter
- 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.)
- Expired
Links
Classifications
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01H—ELECTRIC SWITCHES; RELAYS; SELECTORS; EMERGENCY PROTECTIVE DEVICES
- H01H37/00—Thermally-actuated switches
- H01H37/02—Details
- H01H37/32—Thermally-sensitive members
- H01H37/52—Thermally-sensitive members actuated due to deflection of bimetallic element
- H01H37/54—Thermally-sensitive members actuated due to deflection of bimetallic element wherein the bimetallic element is inherently snap acting
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01H—ELECTRIC SWITCHES; RELAYS; SELECTORS; EMERGENCY PROTECTIVE DEVICES
- H01H37/00—Thermally-actuated switches
- H01H37/02—Details
- H01H37/32—Thermally-sensitive members
- H01H37/52—Thermally-sensitive members actuated due to deflection of bimetallic element
- H01H37/54—Thermally-sensitive members actuated due to deflection of bimetallic element wherein the bimetallic element is inherently snap acting
- H01H2037/5463—Thermally-sensitive members actuated due to deflection of bimetallic element wherein the bimetallic element is inherently snap acting the bimetallic snap element forming part of switched circuit
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01H—ELECTRIC SWITCHES; RELAYS; SELECTORS; EMERGENCY PROTECTIVE DEVICES
- H01H37/00—Thermally-actuated switches
- H01H37/02—Details
- H01H37/32—Thermally-sensitive members
- H01H37/52—Thermally-sensitive members actuated due to deflection of bimetallic element
- H01H37/54—Thermally-sensitive members actuated due to deflection of bimetallic element wherein the bimetallic element is inherently snap acting
- H01H2037/5472—Thermally-sensitive members actuated due to deflection of bimetallic element wherein the bimetallic element is inherently snap acting having an omega form, e.g. the bimetallic snap element having a ring shape with a central tongue
Landscapes
- Physics & Mathematics (AREA)
- Thermal Sciences (AREA)
- Thermally Actuated Switches (AREA)
- Audible-Bandwidth Dynamoelectric Transducers Other Than Pickups (AREA)
- Table Devices Or Equipment (AREA)
- Toys (AREA)
Abstract
ABSTRACT OF THE DISCLOSURE
A snap-acting thermally responsive actuator comprises a bimetal sheet having a U-shaped aperture defining a tongue, the sheet having been deformed to a domed configuration in a die pressing operation so that the actuator reverses its curvature with a snap-action with changes in temperature. The actuator may carry an electrical contact and have a high electrical resistance so that currents of 2 amps through the actuator heat the actuator to its operating temperature. The electrical resistance may be increased by forming apertures in the actuator.
A snap-acting thermally responsive actuator comprises a bimetal sheet having a U-shaped aperture defining a tongue, the sheet having been deformed to a domed configuration in a die pressing operation so that the actuator reverses its curvature with a snap-action with changes in temperature. The actuator may carry an electrical contact and have a high electrical resistance so that currents of 2 amps through the actuator heat the actuator to its operating temperature. The electrical resistance may be increased by forming apertures in the actuator.
Description
This invention relates to snap acting thermally . responsive bimeta].lic actuators for use in actuating the i switch contacts of thermally responsive electric switches such as cut-outs,circuit breakers and thermostats.
A well kno~ form of bimetalIic actuator is a bime~allic j disc of domed configurationwhich moves to an oppositely domed configuration with a snap action with changes in temperat~lr~
. The simplicity of discs and their ease of manufacture) the basic operation being pressing a flat disc between steel dies to 1~ l0 a desired domed configuration, has resulted in their wi~7espread . use, despite serious disadvantages.
One disadvantage part~cularly is that with wide differential discs ~ery high peripheral stress con-centrations result ~uring inversion and in consequence the ; 15 operating ~mperature at.which the disc snaps tends to drift ~ ..~
with age and its life is limi.ted by stress-cracking: thus : .
after about l0,000 sperations the disc may stress-crack, whilst .,.
; the operating temperature may have drifted by as much as 20C.
. ` ~ The~net~result is that in use such discs do not have accurately . ~ 20~ determined operating temperatures throughout their life. ~ -Another disadvantage of discs is that of their very small ~a~ge of useful:movement with snap-action which is often~;~of the order oi~the uncertainties in the dimensions of . ~ other:~related components of a switch ill which the disc may 25 ~ be:~incorlorat~d.
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In view of the widespread use of discs, extensive research has been made into their characteristics. There have been various proposals over the past 40 or so years to increase the movement and to increase the accuracy of the operating temperature of discs. For example, radial corrugations have been impressed in a disc, stress-relief . apertures have been inserted at the centre of a disc and mechanical arrangements for transmitting and increasing the effective movement of a disc have been poposed (see for . example British Patent Specification 1031827). Despite the large amount of research that has gone into improving the characteristics of discs, none of the various proposals has ~-done anything more than mitigate to a certamn extent ~he : ~
disadvantages inherent in bimetal discs. : :
, . . . . .
Another type of snap-acting bimetallic actuator which is well known and which avoids most of the disadvantages of discs is that described in British Patent Specification 1 657434. In the preferred form, such a~ actuator comprses ¦ a rectangular sheet or blade of bimetal h ff in~ a central :.. l tongue released from between two outer lege whose end adja-~ cent the free end of the tongue are joined by a b~idge .~: portion. The bridge portion is mechanically crimped to impart a dished con~iguration to the bimetal blade so that ! it moves with changes in temperaturesbetween oppositely 'l ~ dished congiguration 1~ ' ' :, with a snap action. Such an actuator has a much larger amount of movement with snap action than a disc. It is also possible accuratel~ to set the operating temperature, which is in any case more stable under repeated use than t~at of a disc.
A disadvantage of such an actuator is that as a result of the method of deforming the blade by crimping, it cannot be mass produced to a closely predetermined - operating temperature. The main disadvantage is that the life of this actuatorf although greater than that of a disc, tends to be shortened by cracks developing in maximum stress .. . .
concentration areas at the junction of the central tongue with the outer legs.
Thus despite extensive research into and extensive use of various snap-acting bimetallic actuators the need still exists for a thermally responsive snap-acting bimetallic actuator whiFh is suitable for mass production, provides an adequate range of useful movement with snap action, has a reasonably stable operating temperature over its working life, and very importantly has a long working life which is not :1 prematurely ended by stress-cracking.
The present invention provides a snap-acting thermally rosponsI~e bimetallic actuator comprising a member of sheet bimetal having an aperture wlth an outer perimeter portion and an inner perimeter portlon defining a tongue frce at one end, said free end being close to said outer perimeter portion, said inner pcrimetcr portlon and~arcuate portions of said outer perimeter p~rtion smoothly merging at rounded ends of the aperture adjacent the tongue root, an area of said member surround mg said tongue and~ln relation to which said tongue, at least in part, is generslly -~
''~,.5~ ~ 30 ; ~ ceM rally disposed baving been deformed in a die pressing operation ~ 4 _ :~ C '' :, , : , . ~ . , . . : .
to conform in shape to a die of domed configuration, said domed area being such as to reverse its curvature with a snap action with change in temperature, the ~idth of the domed area surround-ing said tongue measured generally radially from the centre of said domed area being greatest in the region of the tongue root and the length of said tongue being greater than the width of the tongue as measured at the mid-point of the length of the tongue.
; An advantage of an actuator according to the invention is that for many applications its range of useful movement with snap-action can be substantially greater than that of an 'lequivalent disc," by which is meant an actuator identical to an actuator according to the invention apart from having no U-shaped aperture and hence no tongue.
A practical measure for many purposes of the useful movement of an actuator is the movement at the free end of said tongue with snap action measured from the periphery of the actuator to one side of the actuator against a nominal force of SOg wt. This useful movement is that which can ordinarily be employed in many typical electrical swi*ches.
It has been found that, using the above measure, an actuator according to the invention can provide between two and three ti=es the useful =ove=ent of an equivalent disc.
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' -, ., , : , It is however the case that the greater the useful move-ment, th~ greater the differential, i.e. the difference in operating temperatures for increasing and decreasing ambient temperature, but this is not important for many applications.
This increase in useful movement is explica-ble in ~hat whilst a disc has only a small useful move-ment, it develops a comparatively large force t~200g wt), far greater than that required to op~n typical switch con-tacts, so that although relieving the stresses in the centre of an ac~uator by providing Said U-shaped aper-ture substantially rsduces the force developet, this is unimpor~ant for most purposes, and the resultant freedom - of movemont of the free end of the tongue results in a magnified, s~ill useful movement of the actuator~
In view of this increased useful movement, it is possible to use cheaper types of bimetal sheeting te.g. Ni-Cr/Ni Pe laminates) rather than the more ex-pensive types having a high manganese content such as ~: 20 are commonly used in discs.
When designing an actuator according to the invention for a particular switch application, besites being necessary to ensure that the tongue can with snap-action develop a sufficient force and movement to open : th~ switch contacts, it is also desirable to so dis-pose and shape the U-sh~ped aperture as to minimise lo-cal stress cuncentraticns and thus maximise the working life of the actuator. This consideration results in certain preferret geometrical shapes of actuator.
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~OS3Z04 Accordingly the invention provides in a preferred form a snap-acting thermally responsive bimetallic actuator comprising a circular member of sheet bimetal having an aperture therein with a circular outer perimeter portion having a diameter of the order of half that of said member and an inner perimeter portion defining a tongue free at one end and tapering at an angle of about 15 towards its free end, said free end being ; close to said outer perimeter portion, said inner and outer perimeter portions smoothly merging at rounded ends of the aperture adjacent the tongue root, an area of said member surrounding said tongue and in relation to which said tongue at least in part, is generally centrally disposed having been deformed in a die-pressing operation to conform in shape to a die of domed configuration and being such as to reverse its curvature with a snap-action with change in temperature, and the radial width of the parts of said member surrounding said tongue progressively reducing . . . .
from a maximum in the region of the tongue root to a j~
; minimum generally opposite the free end of the tongue, said radial wid~h in the region of the tongue root being - more than twice that generally opposite the free end of the tongue, the length of the tongue being greater than the width of the tongue as measured at the mid-point of the length of the tongue.
The design of the region of the tongue root is important as regards the lifetime of the actuator, since it is here that the high stress concentratlons are developed.
1 ~ Sharp corners in this region would tend to provide localised < ~ area of very high stress concentrations; these are avoided by p~oviding the aperture with rounded ends adjacent the tongue root.
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~()53ZQ4 Whilst it has been found advantageous to ha~e the ma~imum radial width of the domed area of the actuator in the region of the tongue root, it is important not elsewhere to so reduce the width of the domed area as to impair the overall mechanical strength of the actuator to the point where it is incapable of delivering the nec-essary de~eloped force on inversion. Likewise the tongue must itself have sufficient mecha~ical strength to deliver the desired developed force. A tongue of tapered shape lends itself to this requirement whilst minimising any tendeney for the tongue itself to invert breadthwise with snap-ection of the actuator which would tend to reduce the useful movement of the free end of the tongue. The breadth of the tongue at its root is desirably of the same order of magnitude as, preferably rather less than, the width of the domed area in the region of the tongue root. The ~ongue length is preferably about 1 to 1 1/2 times the tongue roo~ breadth and the angle of taper of the tongue is desirably bekween 15 to 30. The shape of the free end of the tongue is not critical. If desired, the free ~i : end may be bent to change the reference plane of move-ment of the ~ctuator. The U-shaped slot defining said tongue is pre~rably symmetrically disposed about a dia-, meter of the domed area which diameter is also prefera-bly an axis of symmetry, the longitudinal axis of the tongue ~then coinciding ~ith tho said axis of sy~ otry.
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105320~
Preferably for convenience in manufac~ure the bimetal member of the actuator according to the invention is domed over its whole surface, although if desired, some or all of the tongue may no~ be deformed during the die pressing operation. However other areas of the bimetal member may be provided which are left flat and undeformed;
for example flat ears for mounting purposes may be pro-vided extending from the domed area. Whilst the actuator is preferably circular for convenience in forming between dies, it may have other shapes, for example rectangular or elliptical.
By forming an actuator in accordance with the invention by a die-pressing operation, it is possible to -mass produce actuators in a particularly simple and ef-fective way. It has been found that actuators according to the invention can be formed in mass-production with . more accurately determined operating temperaturesJ andwith better stability, such stabili~y in operating temper-ature being better not only than that of discs but also than that o bimetallic actutators as described in British Patent Spocification 657434. m is stability arises in large measure from the stress relief in said domed area provided by said U-shaped aperture, and from the method of formation by die-pressing such an actuator which creates few undesired and unintentional local stress concentra-tions. The lack of such stress concentrations also con-tributes to an accurately determined operating temperature.
Thus an actuator according to ~he present invention can ..:
' lOS3Z~)4 have various advantageous features, ln particular a large range of useful movement and an accurately predetermined and stable operating temperature. Depending on the particular application envisaged, the actuator will be designed to emphasize one or other of such features. Thus for an inexpenslve cut-out for high currents, a large range of useful movement will be required to ensure satisfactorv ~j operation. However a large range of movement involves a high ~s , ~ .
- differential between the operating temperatures of the actuator ? lo for increasing and decreasing temperature and this may be undesirable for example in some forms of thermostat where a low differential is required, but an accurately predeter-I mined and stable operating temperature is necessary. Again, ¦ for example, for circ~it breakers sensitive to an excess 1 15 current in a circuit, neither a large range of useful movement nor an accurately predetermined operating temperature -is required, merely an adequate range of movement together 1- with a reasonable consistency and stability in the operating ¦~ temperature so that excess current may reliably be detected.
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~ 05 3Z O 4 In some applications, the actuator may be loosely nounted; in other applications the actuator may be welded or rivetted toa mounting boss and may in addition carry an electrical contact. l~e actuator may suitably be mounted at the free end of its tongue, - , .
~ç where the effects on stresses in thè actuator will t be at a minimum or on the periphery of the actuator opposite the free end of the tongue.
For actuators arranged to be incorporated in curren- sensitive switches, an electrical contact is mounted on the actuator so that current can pass .,~ .
through the actuator, the actuator being heated ~;~ above its operating temperature as a result of excess current. A major problem with known current sensitive actuators is to increase their electrical resistance to current flow so that they respond to relatively low .~ .
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1053~(:)4 currents while ensuring that the actuator is not unduly mechanically weakened. Thus reducing the bimetal thickness and the overall dimensions of an actuator will increase electrical reslstance, but it may unduly weaken the actuator.
This problern is particularly acute since it is common nowadays to require sensitivity to currents of about 2 amps.
For the production of current sensitivities of such low order, British Patent 1363541 discloses and claims a switch-actuating element of the type comprising a sheet or strip .
10 of flexib'.e bimetal.lic material having a tongue released therefrom between two outer legs, the tongue being connected to the sheet or strip at one end and being free of the sheet or strip at the o.ther end, and the sheet or strip being stressed so that it is caused to buckle in two directions so15 - as to be movable with changes in temperature between two positions on either side of an intermediate unstable position with a snap action, wherein the tongue and/or the outer legs of the element have perforations such as to increase th electrical resistance to current flow longitudinally therethrough. The actuator specifically described in Patent 1363541 is of the type described in British Patent : ~ -Specification 657434 wherein the outer legs are bridged adjacent the free end of the tongue, and the bridging portion .". , is crimped to draw the endsof the legs together.
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It has been found that the actuator according to the invention isintri~ically more suitable~use in a current sensitive switch than ~he actuator described in Specification 6S7434, which in order to provide thc necessary ; 5 mechanical strength and stability has rather wide legs and tongue and is formed of rather thick ~imetal and hence does not have substantial electrical resistance. In contrast the actuator according to the ~nvention, having the stress concentrations necessary for snap action disposed in the periphery and tongue root which are inherently strong and stable regions, may be formed of thin bimetal and of ~mall dimensions. -In order to increase the electrical resistance and hence sensitivity of the actuator according to the invention, 1 15 the periphery may be narrowed, particularly in the regions opposite the tongue root. Alternatively perforations,following British Patent1363541, may be formed in such regions. The tongue may also be narrowed or alternatively and as preferred ; for maintainlng the strength of the tongue, may have an aperture or apertures, preferably formed as a longitudinal ,~
l ~ slot.
~ ~ , ' 1053ZO~L
Preferred embodiments of the invention will now be described with reference to the accompanying drawings wherein:
Figure 1 to 7 are plan views of actuators according to the invention;
Figure 8 is a table of parameters for the actuators of Figures 1 to 5; and Figure 9 is a cross-sectional view of an actuator according to the invention.
All the actuators shown except that in Figure 5 have a circular perimeter.
Whilst a circular form is preferred for convenience in mass production, it has been found that that precise shape of the periphery is not critical to the operation of the actuator and that, for exampleJ a rectangular shape is equally good.
Each actuator, apart from that shown in Figure 5, has a semicircular locating recess 10 in its periphery. Each actuator has a tongue 12 at least in part centrally disposed ~-of the actuator formed by a generally U-shaped aperture 14 ~ -with a generally arcuate outer perimeter.
The actuators are formed in a die pressing operation in :
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which a spherical curvature is imparted over the entire actuator surface. Conventional die pressing operations may be employed.
The differences between the various actuators sho~
reside in the shape and position of tongue 12 and aperture l~
and these differences give rise to their differing operating characteristics some of which are lndicated in Figure 8.
Ii The figureslisted in Fig 8 are for selected actuatorsall formed by the same method with an equal spherical radius ;~
of curvature, a diameter of 12 mm and formed from 0.2 mr, thick bimetal. The blades have been selected as having a -~
break temperature of 100C so that their differential and useful movement are comparable. Whilst the values given are representative of the various shapes, they should not necess-arily be taken as median values for actuators produced in those particular shapes.
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Considering the values given it will be noted that the ~ ran8e of useful movement is considerably greater than that ; ~ ~ of an equivalent disc, the smallest range being 0.32 mm for ~: ~
~; ~ 20 the element of Figure 2, i.e. about 1.8-2.2 times that of an "equivalent disc" whe.eas the larger:t range, for the elements of Figures 4 and 5 is 0.45 ~n, about 2.5-3 times . ~
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that o~ an "~quîvalent disc".
The differential for the actuators is between 30 and 40C.
The differential for any particular shape is dependent of the movement of the actuator and hence in order to reduce slgnificantly the differential, it will usually be necessary to reduce the movement.
The actuators sho~ ir Figs 1 and 2 have a tongue 12 of constant width, 2.5 mm, with a semicircular end. The actuator shown in Fig 1 has a relatively long tongue measuring 4.5 mm from tip to root. Aperture 14 has relatively large side lobes 16 formed with 1 mm radius rounded ends adjacent the t~ngue root 18 and a 3.5 mm radius outer perimeter.
The margin 20 is of roughly constant radial width, 2.5 mm, ` although it widens very slightly adjacent the tongue root.
As sho~m in Figure ~ a representative value for the 1 useful movement of the actuator of Figure 1 is 0.36 mm for a ¦ differential of 37C, I The actuator of Flgure 2 has a tongue 12 measuring 3.5 ~m ~-from tip to root and an aperture 14 formed with 0.75 mm radlls ~l 20 rounded ends adjacent tongue root 18 and a 3.00 mm radius outer perimeter. The margin 20 is of roughly constant width, ~ 3.00 mm. .~s shown in Figure ~ a representative value for the '7 useful movement of the actuator of Figure 2 is 0.32 mm for a differential of 37C.
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lOS;~2()4 The actuator~ of Figures 1 an~ 2 have constant width tongues and constant width margins. It has been found that constant width tongues are not whol]y desirable since whilst tlle tongue should be wide at ts root for mechanical strength, substantlal width in its central regions is undesirable as the tongue tends to invert across its width with snap act.on~
of the actuator, resulting in a smaller movement. Similarly a constant width margin is not preferred, rather it has been , ound that a better compromise of the various design fa-tors involved is achieved by a maximum margin width in the region ~ of the tongue root which width progressively reduces to a ; minimum opposite the free end of the ~ongue.
! Acc~rdingly the actuators of Figures 3 and 4 have been proposed, with tongues tapering from their roots and their ,l 15 margins continuously decreasing from a maxlmum in the region of 71 the tongue root to a minimum opposit~ the free end of the tongue.
, The actuator of Figure 3 has a ~ide tongue root, namely , ; 4 mm. The tongue 12 tapers with a ~0~ taper to a semicircular 1 mm radius free end. The tongue is 4 mm long. The aperture 14 has rounded ends 0.75 mm radius ~t the tongue root and its outer perimeter is defined by an arc of 3.50 mm radius whose ~t ,, ~¦ centre is displaced 1 mm from the centre of the actuator.
This results in a margin 3 5 mm wide at the tongue and ~1 ' ' .
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- 1053Z(~4 decreasing contlnuously to a minirn~lrn of 1. 5 t~n opposite the free end of the tongue. As show~ in Figure ~ a representative value of the useful movement of this actuator is 0.34 mm with a differential of 34C. ~'' In Figure 4, the actnator tongue 12 tapers at 15 from a tongue root 3.5 mm wide to a rounded free end with a l~m - radius. The tongue is 4.5 mm long. The aperture 14 has rounded ends o 0.75 mm radius adjacent the tongue root and the outer perimeter of the aperturs is defined by an arc of 3,50 mm radius whose centre is spaced 1 mm from the centre of the actuator. The margin has a ~idth at the tongue root of 3.5 mm decreasing to a mi,nimum of l,5 mm opposite the free end of the tongue. From Figure ~5 a representative value of the useful movement of the actuator is 0.45 mm w;th 38C
differential. It has been found that the actuator of Figure 4'offers overall minimum stress concentrations as a result of its flowing contours. The wide margin at the --tongue root provides ample strength in the snap action movement and the actuator has proved to have a very stable break ~' -temperature (2-3C after 10,000 operations) and it has no abnormally high local stress concentrations where cracking is likely to occur."
The actuator of Figure 5 has an internal shape of tongue and aperture exactly the same as that of Figure 4. It llas - _ 18- -. . .. , .. . . . - ' ., ., ,, . ........ . . ~ . . ,~ , . . .
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been fo~mcl tllat the characteristics are similar; the 12 mm squ~re pe-iphery of FLgure 5 not afecting the operat;on of the actuator to any significant exten~.
~he actua~ors of ~igu~es 6 and ~ are intended ~or use with current sensitive switches ~contact-breakers) and have a contact 22 welded to the margin 20 opposite the free end of tongue 12. In use current flows from the free end of the tongue, through the tongue root and both parts of margin 20 to contact 22.
Both actuators of Figures 6 and 7 have the same general configurati.on as that shown in Figllre 4, but in order to increase théir electr1cal resistance to current flow, they are smaller, being 10 mm in diameter, and are formed from O.1 mm thick bimetal. Both actuators have a longitudina] slot 24 in tongue 12 to increase electrical resistance. The ¦ actuator of Figure 7 has three circular apertures 28 either side of contact 22 in the narro~est portion of margin 20 and this serves substantially to increase electrical resistance.
` The actuator of Figure 6, instead of apertures in its margin, has its margin in the region 26 either side of contact 22 ¦ substantially narrowed as compared wi~h the margin in Figure 7 1; whilst still being thick enough to ensure cufficient force is .1 .
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produced in the snap action, This also serves substantially to increase electrical resistance.
Both actua~ors of Figures 6 and 7 are sensitive to currents as low as 2 amps to perform a snap action movement, Various other arrangements may be envisaged for increasing electrical resistance. Thus the tongue may be ' spl;t into two separate tongue portions each extending Il from the same tongue root.
,~ The electrical contact need not necessarily be positioned ,i 10 on the periphery adjacent the f ee end o~ the tongue but ~, could for example be positioned on the tongue itself or 7 any other convenient position~ In addition more than one contac4 may be employed.
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A well kno~ form of bimetalIic actuator is a bime~allic j disc of domed configurationwhich moves to an oppositely domed configuration with a snap action with changes in temperat~lr~
. The simplicity of discs and their ease of manufacture) the basic operation being pressing a flat disc between steel dies to 1~ l0 a desired domed configuration, has resulted in their wi~7espread . use, despite serious disadvantages.
One disadvantage part~cularly is that with wide differential discs ~ery high peripheral stress con-centrations result ~uring inversion and in consequence the ; 15 operating ~mperature at.which the disc snaps tends to drift ~ ..~
with age and its life is limi.ted by stress-cracking: thus : .
after about l0,000 sperations the disc may stress-crack, whilst .,.
; the operating temperature may have drifted by as much as 20C.
. ` ~ The~net~result is that in use such discs do not have accurately . ~ 20~ determined operating temperatures throughout their life. ~ -Another disadvantage of discs is that of their very small ~a~ge of useful:movement with snap-action which is often~;~of the order oi~the uncertainties in the dimensions of . ~ other:~related components of a switch ill which the disc may 25 ~ be:~incorlorat~d.
, :
In view of the widespread use of discs, extensive research has been made into their characteristics. There have been various proposals over the past 40 or so years to increase the movement and to increase the accuracy of the operating temperature of discs. For example, radial corrugations have been impressed in a disc, stress-relief . apertures have been inserted at the centre of a disc and mechanical arrangements for transmitting and increasing the effective movement of a disc have been poposed (see for . example British Patent Specification 1031827). Despite the large amount of research that has gone into improving the characteristics of discs, none of the various proposals has ~-done anything more than mitigate to a certamn extent ~he : ~
disadvantages inherent in bimetal discs. : :
, . . . . .
Another type of snap-acting bimetallic actuator which is well known and which avoids most of the disadvantages of discs is that described in British Patent Specification 1 657434. In the preferred form, such a~ actuator comprses ¦ a rectangular sheet or blade of bimetal h ff in~ a central :.. l tongue released from between two outer lege whose end adja-~ cent the free end of the tongue are joined by a b~idge .~: portion. The bridge portion is mechanically crimped to impart a dished con~iguration to the bimetal blade so that ! it moves with changes in temperaturesbetween oppositely 'l ~ dished congiguration 1~ ' ' :, with a snap action. Such an actuator has a much larger amount of movement with snap action than a disc. It is also possible accuratel~ to set the operating temperature, which is in any case more stable under repeated use than t~at of a disc.
A disadvantage of such an actuator is that as a result of the method of deforming the blade by crimping, it cannot be mass produced to a closely predetermined - operating temperature. The main disadvantage is that the life of this actuatorf although greater than that of a disc, tends to be shortened by cracks developing in maximum stress .. . .
concentration areas at the junction of the central tongue with the outer legs.
Thus despite extensive research into and extensive use of various snap-acting bimetallic actuators the need still exists for a thermally responsive snap-acting bimetallic actuator whiFh is suitable for mass production, provides an adequate range of useful movement with snap action, has a reasonably stable operating temperature over its working life, and very importantly has a long working life which is not :1 prematurely ended by stress-cracking.
The present invention provides a snap-acting thermally rosponsI~e bimetallic actuator comprising a member of sheet bimetal having an aperture wlth an outer perimeter portion and an inner perimeter portlon defining a tongue frce at one end, said free end being close to said outer perimeter portion, said inner pcrimetcr portlon and~arcuate portions of said outer perimeter p~rtion smoothly merging at rounded ends of the aperture adjacent the tongue root, an area of said member surround mg said tongue and~ln relation to which said tongue, at least in part, is generslly -~
''~,.5~ ~ 30 ; ~ ceM rally disposed baving been deformed in a die pressing operation ~ 4 _ :~ C '' :, , : , . ~ . , . . : .
to conform in shape to a die of domed configuration, said domed area being such as to reverse its curvature with a snap action with change in temperature, the ~idth of the domed area surround-ing said tongue measured generally radially from the centre of said domed area being greatest in the region of the tongue root and the length of said tongue being greater than the width of the tongue as measured at the mid-point of the length of the tongue.
; An advantage of an actuator according to the invention is that for many applications its range of useful movement with snap-action can be substantially greater than that of an 'lequivalent disc," by which is meant an actuator identical to an actuator according to the invention apart from having no U-shaped aperture and hence no tongue.
A practical measure for many purposes of the useful movement of an actuator is the movement at the free end of said tongue with snap action measured from the periphery of the actuator to one side of the actuator against a nominal force of SOg wt. This useful movement is that which can ordinarily be employed in many typical electrical swi*ches.
It has been found that, using the above measure, an actuator according to the invention can provide between two and three ti=es the useful =ove=ent of an equivalent disc.
. ' ' C : ~
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' -, ., , : , It is however the case that the greater the useful move-ment, th~ greater the differential, i.e. the difference in operating temperatures for increasing and decreasing ambient temperature, but this is not important for many applications.
This increase in useful movement is explica-ble in ~hat whilst a disc has only a small useful move-ment, it develops a comparatively large force t~200g wt), far greater than that required to op~n typical switch con-tacts, so that although relieving the stresses in the centre of an ac~uator by providing Said U-shaped aper-ture substantially rsduces the force developet, this is unimpor~ant for most purposes, and the resultant freedom - of movemont of the free end of the tongue results in a magnified, s~ill useful movement of the actuator~
In view of this increased useful movement, it is possible to use cheaper types of bimetal sheeting te.g. Ni-Cr/Ni Pe laminates) rather than the more ex-pensive types having a high manganese content such as ~: 20 are commonly used in discs.
When designing an actuator according to the invention for a particular switch application, besites being necessary to ensure that the tongue can with snap-action develop a sufficient force and movement to open : th~ switch contacts, it is also desirable to so dis-pose and shape the U-sh~ped aperture as to minimise lo-cal stress cuncentraticns and thus maximise the working life of the actuator. This consideration results in certain preferret geometrical shapes of actuator.
. ~
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:
~OS3Z04 Accordingly the invention provides in a preferred form a snap-acting thermally responsive bimetallic actuator comprising a circular member of sheet bimetal having an aperture therein with a circular outer perimeter portion having a diameter of the order of half that of said member and an inner perimeter portion defining a tongue free at one end and tapering at an angle of about 15 towards its free end, said free end being ; close to said outer perimeter portion, said inner and outer perimeter portions smoothly merging at rounded ends of the aperture adjacent the tongue root, an area of said member surrounding said tongue and in relation to which said tongue at least in part, is generally centrally disposed having been deformed in a die-pressing operation to conform in shape to a die of domed configuration and being such as to reverse its curvature with a snap-action with change in temperature, and the radial width of the parts of said member surrounding said tongue progressively reducing . . . .
from a maximum in the region of the tongue root to a j~
; minimum generally opposite the free end of the tongue, said radial wid~h in the region of the tongue root being - more than twice that generally opposite the free end of the tongue, the length of the tongue being greater than the width of the tongue as measured at the mid-point of the length of the tongue.
The design of the region of the tongue root is important as regards the lifetime of the actuator, since it is here that the high stress concentratlons are developed.
1 ~ Sharp corners in this region would tend to provide localised < ~ area of very high stress concentrations; these are avoided by p~oviding the aperture with rounded ends adjacent the tongue root.
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~()53ZQ4 Whilst it has been found advantageous to ha~e the ma~imum radial width of the domed area of the actuator in the region of the tongue root, it is important not elsewhere to so reduce the width of the domed area as to impair the overall mechanical strength of the actuator to the point where it is incapable of delivering the nec-essary de~eloped force on inversion. Likewise the tongue must itself have sufficient mecha~ical strength to deliver the desired developed force. A tongue of tapered shape lends itself to this requirement whilst minimising any tendeney for the tongue itself to invert breadthwise with snap-ection of the actuator which would tend to reduce the useful movement of the free end of the tongue. The breadth of the tongue at its root is desirably of the same order of magnitude as, preferably rather less than, the width of the domed area in the region of the tongue root. The ~ongue length is preferably about 1 to 1 1/2 times the tongue roo~ breadth and the angle of taper of the tongue is desirably bekween 15 to 30. The shape of the free end of the tongue is not critical. If desired, the free ~i : end may be bent to change the reference plane of move-ment of the ~ctuator. The U-shaped slot defining said tongue is pre~rably symmetrically disposed about a dia-, meter of the domed area which diameter is also prefera-bly an axis of symmetry, the longitudinal axis of the tongue ~then coinciding ~ith tho said axis of sy~ otry.
-:
105320~
Preferably for convenience in manufac~ure the bimetal member of the actuator according to the invention is domed over its whole surface, although if desired, some or all of the tongue may no~ be deformed during the die pressing operation. However other areas of the bimetal member may be provided which are left flat and undeformed;
for example flat ears for mounting purposes may be pro-vided extending from the domed area. Whilst the actuator is preferably circular for convenience in forming between dies, it may have other shapes, for example rectangular or elliptical.
By forming an actuator in accordance with the invention by a die-pressing operation, it is possible to -mass produce actuators in a particularly simple and ef-fective way. It has been found that actuators according to the invention can be formed in mass-production with . more accurately determined operating temperaturesJ andwith better stability, such stabili~y in operating temper-ature being better not only than that of discs but also than that o bimetallic actutators as described in British Patent Spocification 657434. m is stability arises in large measure from the stress relief in said domed area provided by said U-shaped aperture, and from the method of formation by die-pressing such an actuator which creates few undesired and unintentional local stress concentra-tions. The lack of such stress concentrations also con-tributes to an accurately determined operating temperature.
Thus an actuator according to ~he present invention can ..:
' lOS3Z~)4 have various advantageous features, ln particular a large range of useful movement and an accurately predetermined and stable operating temperature. Depending on the particular application envisaged, the actuator will be designed to emphasize one or other of such features. Thus for an inexpenslve cut-out for high currents, a large range of useful movement will be required to ensure satisfactorv ~j operation. However a large range of movement involves a high ~s , ~ .
- differential between the operating temperatures of the actuator ? lo for increasing and decreasing temperature and this may be undesirable for example in some forms of thermostat where a low differential is required, but an accurately predeter-I mined and stable operating temperature is necessary. Again, ¦ for example, for circ~it breakers sensitive to an excess 1 15 current in a circuit, neither a large range of useful movement nor an accurately predetermined operating temperature -is required, merely an adequate range of movement together 1- with a reasonable consistency and stability in the operating ¦~ temperature so that excess current may reliably be detected.
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~ 05 3Z O 4 In some applications, the actuator may be loosely nounted; in other applications the actuator may be welded or rivetted toa mounting boss and may in addition carry an electrical contact. l~e actuator may suitably be mounted at the free end of its tongue, - , .
~ç where the effects on stresses in thè actuator will t be at a minimum or on the periphery of the actuator opposite the free end of the tongue.
For actuators arranged to be incorporated in curren- sensitive switches, an electrical contact is mounted on the actuator so that current can pass .,~ .
through the actuator, the actuator being heated ~;~ above its operating temperature as a result of excess current. A major problem with known current sensitive actuators is to increase their electrical resistance to current flow so that they respond to relatively low .~ .
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1053~(:)4 currents while ensuring that the actuator is not unduly mechanically weakened. Thus reducing the bimetal thickness and the overall dimensions of an actuator will increase electrical reslstance, but it may unduly weaken the actuator.
This problern is particularly acute since it is common nowadays to require sensitivity to currents of about 2 amps.
For the production of current sensitivities of such low order, British Patent 1363541 discloses and claims a switch-actuating element of the type comprising a sheet or strip .
10 of flexib'.e bimetal.lic material having a tongue released therefrom between two outer legs, the tongue being connected to the sheet or strip at one end and being free of the sheet or strip at the o.ther end, and the sheet or strip being stressed so that it is caused to buckle in two directions so15 - as to be movable with changes in temperature between two positions on either side of an intermediate unstable position with a snap action, wherein the tongue and/or the outer legs of the element have perforations such as to increase th electrical resistance to current flow longitudinally therethrough. The actuator specifically described in Patent 1363541 is of the type described in British Patent : ~ -Specification 657434 wherein the outer legs are bridged adjacent the free end of the tongue, and the bridging portion .". , is crimped to draw the endsof the legs together.
.,. '~ ' ~ - ' ' . ' . ' ` . ` '' '.
It has been found that the actuator according to the invention isintri~ically more suitable~use in a current sensitive switch than ~he actuator described in Specification 6S7434, which in order to provide thc necessary ; 5 mechanical strength and stability has rather wide legs and tongue and is formed of rather thick ~imetal and hence does not have substantial electrical resistance. In contrast the actuator according to the ~nvention, having the stress concentrations necessary for snap action disposed in the periphery and tongue root which are inherently strong and stable regions, may be formed of thin bimetal and of ~mall dimensions. -In order to increase the electrical resistance and hence sensitivity of the actuator according to the invention, 1 15 the periphery may be narrowed, particularly in the regions opposite the tongue root. Alternatively perforations,following British Patent1363541, may be formed in such regions. The tongue may also be narrowed or alternatively and as preferred ; for maintainlng the strength of the tongue, may have an aperture or apertures, preferably formed as a longitudinal ,~
l ~ slot.
~ ~ , ' 1053ZO~L
Preferred embodiments of the invention will now be described with reference to the accompanying drawings wherein:
Figure 1 to 7 are plan views of actuators according to the invention;
Figure 8 is a table of parameters for the actuators of Figures 1 to 5; and Figure 9 is a cross-sectional view of an actuator according to the invention.
All the actuators shown except that in Figure 5 have a circular perimeter.
Whilst a circular form is preferred for convenience in mass production, it has been found that that precise shape of the periphery is not critical to the operation of the actuator and that, for exampleJ a rectangular shape is equally good.
Each actuator, apart from that shown in Figure 5, has a semicircular locating recess 10 in its periphery. Each actuator has a tongue 12 at least in part centrally disposed ~-of the actuator formed by a generally U-shaped aperture 14 ~ -with a generally arcuate outer perimeter.
The actuators are formed in a die pressing operation in :
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.
which a spherical curvature is imparted over the entire actuator surface. Conventional die pressing operations may be employed.
The differences between the various actuators sho~
reside in the shape and position of tongue 12 and aperture l~
and these differences give rise to their differing operating characteristics some of which are lndicated in Figure 8.
Ii The figureslisted in Fig 8 are for selected actuatorsall formed by the same method with an equal spherical radius ;~
of curvature, a diameter of 12 mm and formed from 0.2 mr, thick bimetal. The blades have been selected as having a -~
break temperature of 100C so that their differential and useful movement are comparable. Whilst the values given are representative of the various shapes, they should not necess-arily be taken as median values for actuators produced in those particular shapes.
~: :
Considering the values given it will be noted that the ~ ran8e of useful movement is considerably greater than that ; ~ ~ of an equivalent disc, the smallest range being 0.32 mm for ~: ~
~; ~ 20 the element of Figure 2, i.e. about 1.8-2.2 times that of an "equivalent disc" whe.eas the larger:t range, for the elements of Figures 4 and 5 is 0.45 ~n, about 2.5-3 times . ~
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that o~ an "~quîvalent disc".
The differential for the actuators is between 30 and 40C.
The differential for any particular shape is dependent of the movement of the actuator and hence in order to reduce slgnificantly the differential, it will usually be necessary to reduce the movement.
The actuators sho~ ir Figs 1 and 2 have a tongue 12 of constant width, 2.5 mm, with a semicircular end. The actuator shown in Fig 1 has a relatively long tongue measuring 4.5 mm from tip to root. Aperture 14 has relatively large side lobes 16 formed with 1 mm radius rounded ends adjacent the t~ngue root 18 and a 3.5 mm radius outer perimeter.
The margin 20 is of roughly constant radial width, 2.5 mm, ` although it widens very slightly adjacent the tongue root.
As sho~m in Figure ~ a representative value for the 1 useful movement of the actuator of Figure 1 is 0.36 mm for a ¦ differential of 37C, I The actuator of Flgure 2 has a tongue 12 measuring 3.5 ~m ~-from tip to root and an aperture 14 formed with 0.75 mm radlls ~l 20 rounded ends adjacent tongue root 18 and a 3.00 mm radius outer perimeter. The margin 20 is of roughly constant width, ~ 3.00 mm. .~s shown in Figure ~ a representative value for the '7 useful movement of the actuator of Figure 2 is 0.32 mm for a differential of 37C.
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lOS;~2()4 The actuator~ of Figures 1 an~ 2 have constant width tongues and constant width margins. It has been found that constant width tongues are not whol]y desirable since whilst tlle tongue should be wide at ts root for mechanical strength, substantlal width in its central regions is undesirable as the tongue tends to invert across its width with snap act.on~
of the actuator, resulting in a smaller movement. Similarly a constant width margin is not preferred, rather it has been , ound that a better compromise of the various design fa-tors involved is achieved by a maximum margin width in the region ~ of the tongue root which width progressively reduces to a ; minimum opposite the free end of the ~ongue.
! Acc~rdingly the actuators of Figures 3 and 4 have been proposed, with tongues tapering from their roots and their ,l 15 margins continuously decreasing from a maxlmum in the region of 71 the tongue root to a minimum opposit~ the free end of the tongue.
, The actuator of Figure 3 has a ~ide tongue root, namely , ; 4 mm. The tongue 12 tapers with a ~0~ taper to a semicircular 1 mm radius free end. The tongue is 4 mm long. The aperture 14 has rounded ends 0.75 mm radius ~t the tongue root and its outer perimeter is defined by an arc of 3.50 mm radius whose ~t ,, ~¦ centre is displaced 1 mm from the centre of the actuator.
This results in a margin 3 5 mm wide at the tongue and ~1 ' ' .
- 17 ~
: . . . ,~ . .
, .
- 1053Z(~4 decreasing contlnuously to a minirn~lrn of 1. 5 t~n opposite the free end of the tongue. As show~ in Figure ~ a representative value of the useful movement of this actuator is 0.34 mm with a differential of 34C. ~'' In Figure 4, the actnator tongue 12 tapers at 15 from a tongue root 3.5 mm wide to a rounded free end with a l~m - radius. The tongue is 4.5 mm long. The aperture 14 has rounded ends o 0.75 mm radius adjacent the tongue root and the outer perimeter of the aperturs is defined by an arc of 3,50 mm radius whose centre is spaced 1 mm from the centre of the actuator. The margin has a ~idth at the tongue root of 3.5 mm decreasing to a mi,nimum of l,5 mm opposite the free end of the tongue. From Figure ~5 a representative value of the useful movement of the actuator is 0.45 mm w;th 38C
differential. It has been found that the actuator of Figure 4'offers overall minimum stress concentrations as a result of its flowing contours. The wide margin at the --tongue root provides ample strength in the snap action movement and the actuator has proved to have a very stable break ~' -temperature (2-3C after 10,000 operations) and it has no abnormally high local stress concentrations where cracking is likely to occur."
The actuator of Figure 5 has an internal shape of tongue and aperture exactly the same as that of Figure 4. It llas - _ 18- -. . .. , .. . . . - ' ., ., ,, . ........ . . ~ . . ,~ , . . .
; ~ . ~ . . .. . . .. ..... . ..
1~)5 ~
been fo~mcl tllat the characteristics are similar; the 12 mm squ~re pe-iphery of FLgure 5 not afecting the operat;on of the actuator to any significant exten~.
~he actua~ors of ~igu~es 6 and ~ are intended ~or use with current sensitive switches ~contact-breakers) and have a contact 22 welded to the margin 20 opposite the free end of tongue 12. In use current flows from the free end of the tongue, through the tongue root and both parts of margin 20 to contact 22.
Both actuators of Figures 6 and 7 have the same general configurati.on as that shown in Figllre 4, but in order to increase théir electr1cal resistance to current flow, they are smaller, being 10 mm in diameter, and are formed from O.1 mm thick bimetal. Both actuators have a longitudina] slot 24 in tongue 12 to increase electrical resistance. The ¦ actuator of Figure 7 has three circular apertures 28 either side of contact 22 in the narro~est portion of margin 20 and this serves substantially to increase electrical resistance.
` The actuator of Figure 6, instead of apertures in its margin, has its margin in the region 26 either side of contact 22 ¦ substantially narrowed as compared wi~h the margin in Figure 7 1; whilst still being thick enough to ensure cufficient force is .1 .
' . j .
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produced in the snap action, This also serves substantially to increase electrical resistance.
Both actua~ors of Figures 6 and 7 are sensitive to currents as low as 2 amps to perform a snap action movement, Various other arrangements may be envisaged for increasing electrical resistance. Thus the tongue may be ' spl;t into two separate tongue portions each extending Il from the same tongue root.
,~ The electrical contact need not necessarily be positioned ,i 10 on the periphery adjacent the f ee end o~ the tongue but ~, could for example be positioned on the tongue itself or 7 any other convenient position~ In addition more than one contac4 may be employed.
... ..
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,, - - , : ' ' ' ' ' ''' :'
Claims (19)
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. A snap-acting thermally responsive bimetallic actuator comprising a member of sheet bimetal having an aperture with an outer perimeter portion and an inner perimeter portion defining a tongue free at one end, said free end bing close to said outer perimeter portion, said inner perimeter portion and arcuate portions of said outer perimeter portion smoothly merging at rounded ends of the aperture adjacent the tongue root, an area of said member surround-ing said tongue and in relation to which said tongue, at least in part, is generally centrally disposed having been deformed in a die pressing operation to conform in shape to a die of domed configuration, said domed area being such as to reverse its curvature with a snap action with change in temperature, the width of the domed area surrounding said tongue measured generally radially from the centre of said domed area being greatest in the region of the tongue root and the length of said tongue being greater than the width of the tongue as measured at the midpoint of the length of the tongue.
2. An actuator as claimed in claim 1 wherein the radial width of the domed area surrounding said tongue reduces progressively from a maximum in the region of said tongue root to a minimum in the region of the free end of said tongue.
3. An actuator as claimed in claim 2 wherein said maximum width is more than twice said minimum radial width.
4. An actuator as claimed in claim 1 wherein said outer perimeter portion is circular.
5. An actuator as claimed in claim 4 wherein the centre of the circular outer perimeter portion is displaced from the centre of the domed area in the direction of the free end of said tongue.
6. An actuator as claimed in claim 4 or 5 wherein the diameter of said outer perimeter portion is of the order of half the diameter of said domed area.
7. An actuator as claimed in claim 1 wherein the tongue tapers from its root towards its free end.
8. An actuator as claimed in claim 7 wherein the angle of taper of the tongue is between 15° and 30°.
9. An actuator as claimed in claim 1 wherein said aperture is symmetric-ally disposed about a diameter of said domed area.
10. An actuator as claimed in claim 9 wherein said diameter is an axis of symmetry.
11. An actuator as claimed in claim 1, 2 or 3 wherein the actuator is domed over its entire surface.
12. An actuator as claimed in claim 1, 2 or 3 wherein the actuator is circular.
13. An actuator as claimed in claim 1 wherein an electrical contact is mounted at the free end of the tongue.
14. An actuator as claimed in claim 1 wherein an electrical contact is mounted on the periphery of the actuator opposite the free end of the tongue.
15. An actuator as claimed in claim 13 or 14 wherein one or more por-tions of the periphery generally opposite the free end of the tongue have sufficiently small dimensions to provide the main resistance to electrical current passing through the actuator.
16. An actuator as claimed in claim 13 or 14 wherein apertures are formed in the periphery generally opposite the free end of the tongue such as to increase the resistance to current flow therethrough.
17. An actuator as claimed in claim 13 or 14 wherein at least one aperture is formed in the tongue such as to increase the resistance to current flow therethrough.
18. An actuator as claimed in claim 1 wherein said tongue at least in part has not been deformed in said die pressing operation.
19. A snap-acting thermally responsive bimetallic actuator comprising a circular member of sheet bimetal having an aperture therein with a circular outer perimeter portion having a diameter of the order of half that of said member and an inner perimeter portion defining a tongue free at one end and tapering at an angle of about 15° towards its free end, said free end being close to said outer perimeter portion, said inner and outer perimeter portions smoothly merging at rounded ends of the aperture adjacent the tongue root, an area of said member surrounding said tongue and in relation to which said tongue at least in part, is generally centrally disposed having been deformed in a die-pressing operation to conform in shape to a die of domed configuration and being such as to reverse its curvature with a snap-action with change in temperature, and the radial width of the parts of said member surrounding said tongue progressively reducing from a maximum in the region of the tongue root to a minimum generally opposite the free end of the tongue, said radial width in the region of the tongue root being more than twice that generally opposite the free end of the tongue, the length of the tongue being greater than the width of the tongue as measured at the mid-point of the length of the tongue.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB5384774 | 1974-12-12 | ||
| GB4502475A GB1542252A (en) | 1975-10-30 | 1975-10-30 | Snap-acting thermally responsive bimetallic actuators |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1053204A true CA1053204A (en) | 1979-04-24 |
Family
ID=26265499
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA241,645A Expired CA1053204A (en) | 1974-12-12 | 1975-12-12 | Snap-acting thermally responsive bimetallic actuators |
Country Status (17)
| Country | Link |
|---|---|
| JP (1) | JPS6043616B2 (en) |
| AU (1) | AU496784B2 (en) |
| CA (1) | CA1053204A (en) |
| CH (1) | CH611455A5 (en) |
| DD (1) | DD123030A5 (en) |
| DE (1) | DE2556062A1 (en) |
| DK (1) | DK153189C (en) |
| FR (1) | FR2294532A1 (en) |
| HK (1) | HK34981A (en) |
| IE (1) | IE43569B1 (en) |
| IT (1) | IT1052814B (en) |
| LU (1) | LU73999A1 (en) |
| NL (1) | NL7514541A (en) |
| NO (1) | NO143773C (en) |
| NZ (1) | NZ179521A (en) |
| PL (1) | PL118329B1 (en) |
| SE (1) | SE7514097L (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US9355801B2 (en) | 2009-06-05 | 2016-05-31 | Marcel P. HOFSAESS | Bimetal part and temperature-dependent switch equipped therewith |
Families Citing this family (9)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB1546578A (en) * | 1975-10-30 | 1979-05-23 | Taylor J C | Method and apparatus for manufacturing snap-acting thermally responsive bimetallic actuators |
| IE49139B1 (en) * | 1979-01-15 | 1985-08-07 | Taylor John C | Thermally-sensitive electrical controls for electric heaters |
| GB2040572B (en) * | 1979-01-15 | 1983-08-17 | Taylor J C | Switch units for electric immersion heaters |
| US4507642A (en) * | 1982-07-29 | 1985-03-26 | Otter Controls Limited | Snap-acting thermally-responsive bimetallic actuators |
| GB8301624D0 (en) * | 1983-01-21 | 1983-02-23 | Otter Controls Ltd | Electric switches |
| JPS59150136U (en) * | 1983-03-28 | 1984-10-06 | 株式会社東海理化電機製作所 | circuit breaker |
| DE4017864C1 (en) * | 1990-06-02 | 1991-11-07 | Inter Control Hermann Koehler Elektrik Gmbh & Co Kg, 8500 Nuernberg, De | Spring contact for thermal switch - has wide section in free region of operating tongue accepting high bending force |
| ATE295452T1 (en) | 1998-06-09 | 2005-05-15 | Husson Collectivites Sa | CONNECTION NODES |
| DE102009025221A1 (en) * | 2009-06-05 | 2010-12-16 | Hofsaess, Marcel P. | Bimetallic part for use as an active switch element in a temperature-dependent switch, comprises an inner area and an outer area surrounding the inner area, where the inner and outer areas are integrally designed in some sections |
Family Cites Families (9)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB705336A (en) * | 1900-01-01 | |||
| GB716096A (en) * | 1900-01-01 | |||
| US1988345A (en) * | 1933-07-17 | 1935-01-15 | Sidney P Vaughn | Snap action device |
| GB657434A (en) * | 1949-02-07 | 1951-09-19 | Eric Hardman Taylor | Improvements in or relating to snap-action actuating members for electric switches |
| US2632824A (en) * | 1950-08-04 | 1953-03-24 | Wilcolator Co | Thermostat control and bimetal snap-acting element therefor |
| CH299286A (en) * | 1950-12-07 | 1954-06-15 | Becker Kurt | Component. |
| CH296461A (en) * | 1951-08-28 | 1954-02-15 | Bbc Brown Boveri & Cie | Small thermostat. |
| US3139500A (en) * | 1960-03-02 | 1964-06-30 | Wilcolator Co | Thermally actuated double throw switch mechanism |
| GB1363541A (en) * | 1972-01-04 | 1974-08-14 | Otter Controls Ltd | Electrical switches |
-
1975
- 1975-12-12 AU AU87517/75A patent/AU496784B2/en not_active Expired
- 1975-12-12 LU LU73999A patent/LU73999A1/xx unknown
- 1975-12-12 DE DE19752556062 patent/DE2556062A1/en active Granted
- 1975-12-12 SE SE7514097A patent/SE7514097L/en unknown
- 1975-12-12 NZ NZ179521A patent/NZ179521A/en unknown
- 1975-12-12 IT IT52648/75A patent/IT1052814B/en active
- 1975-12-12 DD DD190118A patent/DD123030A5/en unknown
- 1975-12-12 CA CA241,645A patent/CA1053204A/en not_active Expired
- 1975-12-12 JP JP50147506A patent/JPS6043616B2/en not_active Expired
- 1975-12-12 FR FR7538159A patent/FR2294532A1/en active Granted
- 1975-12-12 DK DK565075A patent/DK153189C/en active
- 1975-12-12 NO NO754223A patent/NO143773C/en unknown
- 1975-12-12 CH CH1617675A patent/CH611455A5/en not_active IP Right Cessation
- 1975-12-12 NL NL7514541A patent/NL7514541A/en not_active Application Discontinuation
- 1975-12-12 IE IE2721/75A patent/IE43569B1/en unknown
- 1975-12-12 PL PL1975185471A patent/PL118329B1/en unknown
-
1981
- 1981-07-23 HK HK349/81A patent/HK34981A/en unknown
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US9355801B2 (en) | 2009-06-05 | 2016-05-31 | Marcel P. HOFSAESS | Bimetal part and temperature-dependent switch equipped therewith |
Also Published As
| Publication number | Publication date |
|---|---|
| NO143773B (en) | 1980-12-29 |
| PL118329B1 (en) | 1981-09-30 |
| NO754223L (en) | 1976-06-15 |
| NL7514541A (en) | 1976-06-15 |
| AU496784B2 (en) | 1978-10-26 |
| NZ179521A (en) | 1978-11-13 |
| SE7514097L (en) | 1976-06-14 |
| DE2556062A1 (en) | 1976-06-16 |
| IE43569B1 (en) | 1981-04-08 |
| DK565075A (en) | 1976-06-13 |
| NO143773C (en) | 1981-04-08 |
| AU8751775A (en) | 1977-06-16 |
| DE2556062C2 (en) | 1989-01-26 |
| CH611455A5 (en) | 1979-05-31 |
| FR2294532A1 (en) | 1976-07-09 |
| DK153189B (en) | 1988-06-20 |
| FR2294532B1 (en) | 1981-06-12 |
| DK153189C (en) | 1988-11-07 |
| DD123030A5 (en) | 1976-11-12 |
| JPS51109482A (en) | 1976-09-28 |
| JPS6043616B2 (en) | 1985-09-28 |
| IT1052814B (en) | 1981-07-20 |
| LU73999A1 (en) | 1976-07-01 |
| HK34981A (en) | 1981-07-31 |
| IE43569L (en) | 1976-06-12 |
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