US2259265A - Refrigerating apparatus - Google Patents

Description

Oct. 14, 1941. G. c. PEARCE 2,259,265

REFRIGERATING APPARATUS Filed May 26, 1959 2 Sheets-Sheet 1 INSULHTION l 4l J- z ,p6 2 /l /44 5% He I /04 71 l I .420 H l 4| 4. /5 Il' 70 J0 54 y: 1 F, 6o az l I. o 1 l 46 n al, E I zz l ze u, 7l J8 I l 7g 74- I 24 @'z A 24 ZD I 25 M .l

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v 1N ENTOR BY WV *w/Z/ ATTORNEYS 0d. 14, 1941. G. c. PEARCE 2,259,265

REFRIGERAT ING APPARATUS Filed May 26, 1939 2 Sheets-Sheet 2 INSULATION ae 56 8g 7o. //o

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ATTORNEYS Patented Oct. 14, 1941 2,259,265 REFRIGERATING APPARATUS George C. Pearce, Dayton, Ohio, assignor to General Motors Corporation, Dayton, Ohio, a corporation of Delaware Application May 26, 1939, Serial No. 275,959 v 17 Claims.

This invention relates to refrigerating apparatus and more particularly to refrigerator control means.

It is an object of my invention to provide an inexpensive, accurate, reliable low differential control capable of providing uniform trouble free, results for a long period of time.

Heretofore it has been difficult to provide a switch mechanism capable of carrying heavy currents on a low differential. It has been necessary to use either an expensive magnet type switch, ap'ilot and relay switch or a switch of rather large dimensions. One of the difficulties has been to provide a satisfactory form of `snap acting device, which has a low differential and high current carrying capacity and which is durable and has a long life.

It is an object of my invention to provide a control means with an improved toggle device which has these desirable characteristics and provides an inexpensive form of low differential toggle having a high current carrying capacity.

It is another object f my invention to provide a toggle switch which will not bounce or chatter, which has little friction or wear, and which is simple and reliable. v

Heretofore a differential of ordinary controls has been adjusted by providing a floating member held against a stop by a single spring, which floating member is picked up by the movement of the control device. I have found that when the spring has its tension reduced to a very. small amount that such a device gives unreliable results so that a small adjustable differential cannot be Obtained.

It is an object of my invention to provide a control in which differential adjustment means is provided which can add to the minimum differential provided by the toggle device any added amount of differential from Zero to the maximum desired differential.

It is still another object of my invention to provide an improved form of spring hinge con- Fig. 1 is a View partly in elevation and partly 55 place.

in section of one form of my improved control means taken on the line I-l of Fis'. 4;

Fig. 2 is a sectional view taken along the lines 2 -2 of Fig, 4;

Fig. 3 is a sectional view taken along the lines 3-3 of Fig. 1; and

Fig. 4 is a sectional view taken along the lines v 4-4 of Fig. 1.

Briefly, I have shown a refrigerator control switch mechanism with a high pressure cutout. The switch includes a novel toggle mechanism providing a low differential and a high current carrying capacity. The switch mechanism and The switch mechanism Referring now to the drawings and more particularly to Fig. 1, there is shown a control base v2li formed of pressed steel with a. heavy flange around its edges. 'Ihis base 20 supports a flexible metal bellows 22 which is fastened to the base 20 by a, nut 24 which is threaded onto the neck 26 provided upon the lower end of the bellows 22. The bellows 22 and its neck 26 are preferably connected by capillary tubing 28 to a source of pressure such as a thermostat bulb or some pressure connection which will supply the pressure for operating the control. The bellows 22 1s provided with a conical point 30 at its upper end which bears against the main lever 32 of the sw1tch mechanism. 'I'his main lever 32 is pivoted to a support 34 mounted upon a. platform 36 which is supported at one end of the base by the posts 38. This platform 36 extends substantially across the base 20 and has feet portions extending down at one edge to the base for providing a firm support as is best shown in `Fig. 2.

The main leoer and spring hinge 'I'he support 34 supports a leaf spring 40 over which is a supporting plate 42 which is held in place by a rivethead formed on top of the support 34. The rivet head holds the support plate 42 and one end of the leaf spring 40 rmly in 'I'he support plate 42 overlaps the adiacent end of the main lever 32, so that the shear stress at the hinge which is provided by the pressure the bellows 22 is carried not by the leaf spring 40 but by the supporting plate 42. This makes it possible to make the leaf spring 3E very thin so that it is very eXible and will not aect the movement of the main lever 32. The other end of the leaf spring it is riveted to the upper face of the main lever 32 as is clearly shown in Figs. 1 and 4.

This leaf spring hinge connection is superior to prior types of spring hinge connections since the spring member itself carries very little stress overlapping of the end of the main lever 32 by the supporting plate Q2 prevents shearing stress from being applied to the-leaf spring QG. In reality, the only substantial stress upon the leaf spring l0 is a very light pull indirect tension.

This form of hinge is far superior to a knife edge or a pinned hinge since both knife edges and pinned hinges have a certain amount of friction and knife edges are apt to become easily dislodged under rough handling.

It should be noted that the supporting plat-l form 36 has an aperture which receives the conical point of the bellows 22. The platform '3B overlies the upper end of the bellows 22 and serves as a stop to prevent damage to the bellows 22 by excessive internal pressure.

The toggle. and contact mechanism The other end of the main lever 32 is provided with a connecting member it of insulating material. This connecting member li may be molded directly onto this end of the main lever. Fastened to the end portion of the connector member lil is a two-armspring support d6 to which is hooked one end of each of the two light tension toggle springs 63. The other end of each of the toggle springs it is hooked to the end of a relatively rigid arm 5@ which is provided with a pair of ears 52 for this purpose. These ears .52 are provided at the end of wings or projections so as to hold the toggle springs d3 on either side of the arm 5@ but in substantial alignment with the arm 5d. This end of the arm 52 moves between stops, one of which is in the form of an L-shaped stop 56 which is riveted to the top of a conductor post 5t.

This conductor post 56 at its lower end is riveted to an electrical conductor strip 58 to which an electrical conductor may be fastened by means vof a screw threaded into the outer end of the arm 58 is provided with an oiset portion EB adjacent the riveted portion so as to allow the center line of the toggle springs 48 to move across the plane of the -leaf spring BD.

This permits the leaf spring 60 to bend freely in between the contact portion and the conduct- 'Ihe other ends of the leaf spring EB and ing post 56 which serves as an anchor for the leaf spring 64. The contact 62 is adapted to make contact with the contact post 66 which is riveted onto the conductor strip 63 to which another conductor may be fastened by a suitable screw. This contact post BG of course serves as a stop for the movement of the contact 62 in one direction. The movement of the contact-62 into open position is limited by a small set-screw l0 which is held in an insulating arm at 'l2 projecting from the wall of an insulating casing l2 which supports the toggle mechanism of the contact mechanism. This insulating casing 72 has a Vdownwardly extending portion 'M which is fastened to base 2B and holds the insulating casing l2 in proper relation to the bellows 22 and the main lever 32.

The toggle mechanism is shown with the contact E? in the open position. 'Ihe toggle springs i8 are below the plane of the leaf spring 60. When this control is used in a refrigerating system, the compressor will be idle when the con-- tacts are open and the temperature and pressure will increase in-the bellows 22 during the said period. This will cause the bellows 22 to expand and raise the main lever 32. The raising of the mainrlever 32 will cause one end of the toggle spring 48 to cross the plane of the leaf spring 5E and when this end of the toggle spring is carried sufciently far, the toggle mechanism will snap the contacts t2 down onto the top of the contact post 65. At this time the other end of the rigid arm 5i? will move from its position on top of the leaf spring t@ to a position near to or against the stop 56. As long as the main lever 32 moves within normal limits, the stop 555 is unnecessary. This arrangement will cause the contact 62 to be held closed with considerable contact pressure.

I find with this toggle mechanism, that there is no bouncing of the contacts when the switch is closed. 'Ihis prevents the burning of the contacts and aids in the carrying of heavy initial currents and is a factor in obtaining long life out of the contacts. The closing of the contacts will cause the-refrigerating system to operate and to reduce the pressure within the bellows 22. This reduction in pressure within the bellows 22 will lower the ends of the toggle springs it which areV connected to the main lever 32. This will also pull the ears 52 gradually downwardly so that while the contacts are closed, the arm 5d gradually pivots itself upon the fulcrum of the pivot formed by the contact E2 resting upon the contact post 65. This pivoting will continue un- `til the tripping point is reached after which the tacts causes the contacts to engage at one point.

upon closing and to be in contact at another point when the switch opens. There also appears to be a beneficial wiping action provided between the contacts by the pivoting'of the rigid arm 50 during the time that the contacts are in engagement. I find that this mechanism makes it possible to carry comparatively large currentswithout the burning of the contacts and in fact makes it possible for the contacts to have along life. There is very little, if any, arcing at the contacts.

Only one set of contacts are required in this arrangement. 'Ihe leaf springV 60 serves as the conductor between the movable contact and the binding post. so that no pig-tail connections are required and no shunt contacts need be provided. There is substantially no friction to this form of toggle mechanism and also substantially no wear so that the switch should provide uniform operating conditions throughout its life. 'I'he leaf spring i8 is held in tension at all times and therefore may be made very thin. Bymaking this leaf spring thin there is less bending stress in the leaf spring and the leaf spring will have a lesser spring force so that a very low differential is incorporated in this ltoggle mechanism. 'I'he only compression member in the mechanism is the rigid arm 58 which can be made sufflciently thick to prevent it from being bent under any normal stress. The stress upon the rigid arm 58 is not great since it is required only to withstand the stress imposed by the toggle springs 48. It has been found that a relatively large amount of current can be carried even though the toggle springs 48 are comparatively weak. The weight of the p arts of the .toggle mechanism is very small so that inertia effects will be minimized. This probably accounts for the fact that this toggle mechanism can provide a relatively large current carrying capacity with a relatively small differential and a relatively small contact pressure.

The range adjustment The movement of the main lever 32 is controlled by a main spring 88 which is carried at its lower end by a spring retainer 82 provided with the conical point which rests in a notch provided in the upper face of the lever 32. The upper end of the spring 88 is supported by a spring retainer 84 which is threaded onto an adjusting screw 86, This adjusting screw 86 is rotatably mounted within an inverted U-shaped bracket 88 which has its lower endsv fastened to the platform 36. The upper end of the screw 86 is provided with a two-part head provided with a bearing in the bracket 88 located between the two parts of the head. yThese two parts of the head are rigidly held together by a threaded connection which is locked in place by riveting the threaded end. The head lof the screw is provided with a screw-driver slot for adjustment. The upper spring retainer 84 is provided with a projection 98 which extends into a vertical slot provided in the side wall of the bracket 88 so as to guide the retainer 84 and to prevent its rotation and also to serve as an indicator of the tension of the main spring 88. The position of the indicating projection may be calibrated and an adjustable scale 92 may be provided upon the outer face of therbracket 88 so that the setting of the switch will be indicated in the form of pound pressure or degrees.

The differential adjustment The operation of the main lever 82 is also controlled by an improved form of differential adthat such"a differential adjustment gives erratic results. This is probably due to the fact that considerable slack is provided when the spring is loosened sufficiently to reduce the differential to a minimum. I have provided a differential adjustment which does not become slack or loose at minimum differentials and which will provide extremely small and very accurate additions to the differential provided by the snap acting mechanism.

In order to do this I have provided a floating member 94 which is provided with upper and lower threaded portions. A tension coil spring 96 is threaded onto the lower threaded portion and extends downwardly to the base where it is threaded onto a threaded stud anchor 98. The

floating member 94 is provided with a stop in the form of a set-screw |82 extending upwardly from the base within the lower spring 96. The upper end of this set-screw has a conical point which normally rests in a notch in the bottom of the floating member 94. The upper threaded portion of the floating member 94 receives the lower end of the upper tension coil spring |84 which has its upper end connected to the outer threaded portion of the differential adjusting nut |86 which is threaded onto the differential adjusting screw |88. The head of the differential adjusting screw |88 rests upon the top of the inverted -shaped bracket 88.

, The differential adjusting nut |86 is provided with an indicating arm ||8 which rides within a slot in the side wall of the bracket 88. This indicating arm, like the indicating arm 98, prevents the rotation of the nut |86 and also cooperates with the scale member ||2 which .is calibrated to indicate the differential adjustment provided by any position of the differential ad justing nut |86. In this differential adjustment the spring 98 is provided with sufficient tension to provide more than the maximum differential desired. The upper spring |84 is provided with as much tension as is desired in order to reduce the amount of differential provided by the lower spring 96.

It will be understood that if the tension of the upper spring |84 is so adjusted that it is equal to the tension f the lower spring 96 that substantially no differential will be provided by the floating. member 94. Under such conditions the floating member 94 will be lifted off its stop screw |82 by the tension of the spring `|84 and the floating member 94 will be raised so that the lever 32 will be free to move without contacting the floating member 84. It should be noted that the lever 82 is provided with a notch which receives the reduced portion of the floating member 94 between the two threaded portions which support the adjacent ends of the upper and lower springs. The movement of the main lever 32 between opening and closing positions is less than the distance between the two threaded portions of the floating member 94 so that the main lever may operate freely without contacting the floating member. It should be noted that in this minimum differential position that there is no slack in the differential adjusting mechanism and there is no possibility that any erratic results can be caused by the differential adjusting mechanism.

As it is desired to increase the differential, the tension of the upper spring |84 is gradually reduced so that the main lever 32 will only leave the floating member 94 a very small distance, such as a few thousandths of an inch so as to provide an extremely small differential to be added to the differential of the toggle mechanism. At this time the floating member will remain off its stop screw |82. As the tension of the uppe'r spring |84 is reduced to provide greater differential, the floating member 84 will gradually move downwardly because of the greater margin of force that the lower spring 96 will have over the weakened upper spring |04. This will increase the distance that the floating member Q4 must be lifted by the main lever 32 and this will increase the added differential provided by the differential adjustment. Further decreases in tension of the upper spring |04 will cause the floating member to gradually approach the stop screw 02 and iinally cause it to rest normally upon the stop screw |02. creased differential which may be increased until the tension of the upper spring |063 has been reduced to the minimum tension necessary to hold the differential adjustment in place.

Thus the diiferential adjustment does not depend upon a single spring but depends upon the difference invtension between the lower and the upper springs. This provides a superior diierential adjustment throughout the entire range of diierential settings desired.

The high pressure cutout mechanism At the side of the switch mechanism thus far described I have provided a high pressure cutout mechanism which acts upon the, toggle mechanism to open the contacts under dangerous conditions. Inorder to do this I have provided an internal bellows type of diaphragm operating member which has its neck portion |22 fastened to the base by a nut |26. The neck |22 is connected to capillary tubing |26 which is preferably connected to the high pressure portion of a refrigerating system. The internal bellows operates a plunger provided with a conical upper end which engages a notch in the lower face of the main lever |30 which is provided with an overlapping type of spring hinge connection like that described for the main lever 32. The supporting plate |32 overlaps .the end of the main lever |30 and between the overlapping end of the This will provide a gradually irlprovided upon the top portion of the bracket a8.

When a dangerously high pressure exists in the high pressure portion of the refrigerating system the tension of the main spring' |46 and the toggle spring E38 will be overcome and the lever |00 will move downwardly away from its stop screw 00. This lever 40 is provided with an arm 50 of insulating material which extends over through a notch in the wall of the insulating casing 'i2 into the interior thereof. The extreme end of this arm overlies the end of the rigid arm 50 provided with the ears so that when the lever d50 moves downwardly this arm v i5@ will move the rigid arm downwardly so as to cause the contact 62 to be lifted away from the contact post 66 to stop the operation of the refrigerating system. When the high pressure in the high pressure portion of the system is reduced sufficiently, the main spring |66 will return the double toggle snap acting mechanismv and the operating arm |130 to its ineffective position against the stop screw |40 to permit the switch Contact 62 and its toggle mechanism to operate normally.

While the mechanism has been described as a refrigerator control switch, it obviously has other uses such as temperature and pressure controlled switches for other purposes and valves.

I claim:

l. A control means including a substantially rigid lever member, a substantially rigid supportv ing member overlapping one end of said lever main lever and the supporting plate |32 there is fastened the leaf spring |34 which is fastened to the top of the main lever |30 and beneath the bottom of the supporting plate |32. As mentioned before the overlapping of the lever and the support plate takes the shear stress upon the hinge joint and allows the leaf spring to carry only the direct tension and other minor stresses.

The free end of the main lever |30 is provided with a double toggle snap acting mechanism including a secondary lever |36 pivoted to the end of the main lever by a knife edge construction and connected at its opposite end to a tension toggle spring |38 which is connected at its opposite end to the operating lever |40 of the high pressure cutout mechanism. This operating lever |40 is pivoted upon the pin |42 and is provided with notches for limiting the movement of the free end of the secondary lever |36. The lever |40 is normally held against a stop screw |40 by the toggle spring |38. The toggle mechanism together with the main spring |46 which opposes the upward movement of the plunger within the lower spring retainer |48 which has a conical point which rests ina notch upon the upper face of the main lever |30. Its upper end is retained by an upper spring retainer 50 threaded onto an adjusting screw |52 which is provided with a two-part head rotatably mounted in an aperture member, leaf spring meansV extending between and in contact with the adjacent surfaces of the overlapping portions of each of said members, said leaf spring means being connected to said members, a control device operated by said lever member, and operating means applied to the lever for moving the lever and for holding the leaf spring means against the supporting member.

2. A control means including an operating means having a reciprocating movement, a control device operated by the reciprocating movement of said operating means, snap acting means for controlling the movement of said operating means, a differential adjustment means comprising opposed spring means, an engaging means acted upon by said opposed spring means and located in a portion of the path of movement of a portion of the operating means for engaging and disengaging said portion of the operating means in one portion of its reciprocating movement, a stop means for normally holding said engaging means in a particular portion of the path of movement of said portion of the operating means and for limiting the movement of the engaging means in one direction, and means for adjusting the tension of one of said spring means.

3. A control means including an operating means, a iiexible metal strip supported in cantilever fashion, a relatively rigid member having one portion fastened to said nexible metal strip at a point remote from said anchorage, said member-extending from said point toward the anchorage of said strip, and spring means connecting said operating means and a point upon said rigid member adjacent said anchorage for moving the flexible strip with a snap action and for maintaining a tension upon said strip.

4. A control means including an operating means, a flexible metal strip supported in cantilever fashon, a relatively rigid member having one portion fastenedto said exible metal strip at a point remote from said anchorage, said limiting the movement of the flexible strip.

5. A control means including an operating means, a fiexiblemetal strip supported in cantilever fashion, a relatively rigid member having one portion fastened to saidflexible metal strip at a point remote from said anchorage, said member extending from said point toward the anchorage of said strip, spring means connecting said operating means and a point upon said rigid member adjacent said anchorage for moving the flexible strip with a snap action and for maintaining a tension upon said strip, and electrical contact means carried and operated by said strip.

6. A control means including an operating means, a flexible metal strip supported in cantilever. fashion, a relatively rigid member having one portion fastened to said flexible metal strip atl a point remote from said anchorage, said member extending from said strip toward the anchorage of said strip, and spring means connecting said operating means and a point upon said rigid member adjacentsaid anchorage for moving the, flexible strip with a snap action and for maintaining a tension upon said strip, said spring means being in the form of a tension coil spring.

7. A control means including an operating means, a flexible metal strip'supported in cantilever fashion, a relatively rigid member having one portion fastened to said flexible metal strip at a point remote from said anchorage, said member extending from said point toward the anchorage of said strip, spring means connecting said operating means and a point upon said rigid member adjacent said anchorage for moving the flexible strip with a snap action and for maintaining a tension upon said strip, an electrical -contact fastened to the strip adjacent the connection between the strip and the memfber, a second contact, and a stop means'for limiting the separation of said contacts.

8. A control means including a substantially rigid lever member, a substantially rigid supporting member overlapping one end of said lever member, leaf spring means extending between and in contact with the adjacent surfaces of the overlapping portions of each ci" said members, means 'for connecting' the leaf spring means to each of said members, the adjacent surfaces of Y the overlapping portions of each of said members being separated only by said leaf spring means, a control device operated by said levermember, and means for applying a force to said lever member adjacent said leaf spring means substantially at right angles to said adjacent surfaces in a direction to hold the overlapping portions of said rigid members together with the leaf spring means held tightly between said overlapping portions. f

9. A control means including an operating means having a reciprocating movement, a control device operated by a reciprocating movement of said operating means, a differential adjustment means comprising an engaging means located in a. portion oi' the path of reciprocating movement of a portion oi' the operating means for engaging and disengaging said portion of the operating means in one portion of its reciprocat- 3Q and for limiting the movement of the engaging ing movement, a plurality of tension springs each having an end connected to said engaging means with their opposite ends extending in different directions from the engaging means, anchoring means for said opposite ends of said springs, a stop means for normally holding said engaging means in a particular portion of the path of movement of said portion of the operating means and for limiting the movement of the engaging means in one direction, said springs normally being tensioned to hold the engaging means against said stop means when the engaging means is disengaged from the operating means.

l0. A control means including an operating means having a reciprocating movement, a control device operated by a reciprocating movement of said operating means, a differential adjustment means comprising an engaging means located in a portion of the path of reciprocating movement of 'a portion of the operating means for engaging and disengaging said portion of the operating means in one portion'of its reciprocating movement, a plurality of tension springs each having an end connected to said engaging means with their opposite ends extending in different directions from the engaging means, anchoring means for said opposite ends of said springs, a stop mea'ns for normally holding said engaging means in a particular portion of the path of movement of said portion of the operating meansmeans in one direction, said springs normally being tensioned to hold the engaging means against said stop means when the engaging means is disengaged from the operating means, said engaging means being free of support except for the springs and stop means, and means for adjusting the location of the anchorage of one of said spring means. i

11. A control means including an operating means having a reciprocating movement, a con-n trol device operated by a reciprocating movement of said operating means, a differential adjustment means comprising an engaging means located in a portion of the path of reciprocating movement of a portion of the operating means for engaging and disengaging said portion of the operating means in one portion of its reciprocating movement, a plurality of tension springs each having an end connected to said engaging means with their opposite ends extending in different directions from the engaging means, anchoring means for said opposite ends of said springs, a stop means for normally holding said engaging means in a particular portion of the path of i. movement of said portion of the operating means and for limiting the movement of the engaging means in one direction, said springs normally being tensioned to hold the engaging means against said stop means when the engaging means is disengaged from the operating means, said engaging means being free of support except for the springs and stop means, and means for adjust- .ing the location of said stop means. A

12. A control means including an operating means, a supporting means, a first member Y*ovided with a :first connection connecting to said supporting means, a second member, said first member being provided with a second connection remote from said first connection connecting with said second member, and spring means connecting saidl operating means and a. portion of said second member adjacent said yfirst connection. f

v 13. A control means including an operating means, a supporting means, a nrst member provided with a first connection connecting-to said supporting means, a second member, `said rst member being provided with a second connection remote from said first connection connecting with said second member, spring means connecting said operating means and a portion of said second member adjacent said rm connection, said spring means acting in such s; direction to exert a tension upon said :tirst member between its connections.

i4. A control means including an operating means, a supporting means, a rst member provided with a rstv connection connecting to said supporting means, a second member, said rst member being provided with a second connection remote from said rst .connection connecting with said second member, spring means connecting said operating means and a portion of said second member adjacent said rst connection, and means for providing a limited movement of said second connection.

15. A control means including an operating means, a supporting means, a nrst member provided with a rst connection connecting to said supporting means, a second member, said first member being provided with a second connection remote from said rst connection connecting with said second member, spring means connecting said operating means and a portion oi said second member adjacent said rst connection,

and electrical contact means adjacent to and operated in conjunction with the movement of means, a supporting means, a first member provided with a rst connection connecting to said supporting means, a second member, said rst member being provided with a second connection remote from said rst connection connecting with said secondmember, spring means connecting said operating means and a portion of said second'member adjacent said'rst connection, one of said members being in the form of a iieXible resilient metal strip.

17. A control means including an operating means, a supporting means, a exible strip anchored to said supporting means and extending in cantilever fashion therefrom, and a doubleback-type connecting means connecting said operating means and the free end portion of said iiexible strip, said connecting means including a rst portion rigidly connected to said free end portion of said exible strip extending generally toward the anchoring point of said strip and merging adjacent the anchoring point with a second portion extending generally in the opposite direction to its connection with said operating means, one of said portions including spring means.

' GEORGE C. PEARCE.

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