US 3683305 A
A protective device for air conditioners includes a dialectric housing having a pair of terminals separately mounted therein. A metal connector plate is also mounted within the housing and is tempered so as to bend when exposed to a predetermined temperature from a normal position wherein it engages both of the terminals and completes the electric connection therebetween to an open circuit position wherein it is free from electrical contact with at least one of the terminals. At least one catch is provided on the housing and is adapted for retentively engaging and holding the connector plate in its open circuit position in response to movement of the connector plate to this position. The catch is movable out of retentive engagement with the connector plate, but is urged into retentive engagement by a spring. A reset mechanism is connected to the catch and is adapted to urge the catch out of retentive engagement with the connector plate in response to manual manipulation. The protective device includes means for mounting it upon the casing surrounding an air conditioner compressor and electric motor, and is adapted to sense the heat emanating from the compressor and motor. The terminals of the protective device are connected in series with a power source and the electric motor so that upon sensing a predetermined temperature the protective device breaks the circuit between the power source and the electric motor.
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Description (OCR text may contain errors)
United States Patent Gray  PROTECTIVE DEVICE FOR AIR CONDITIONERS  Inventor: Robert A. Gray, 1913 E. 9th, Des
Moines, Iowa 50316  Filed: July 24, I970 ] Appl. No.: 58,121
UNITED STATES PATENTS l/l935 Bletz ..337/367 l2/l967 Hatch ..337/367 X FOREIGN PATENTS OR APPLICATIONS 622,594 5/1949 Great Britain ..337/9l Primary ExaminerBernard A. Gilheany Assistant ExaminerF. E. Bell Att0meyZarley, McKee & Thomte Aug. 8, 1972  ABSTRACT A protective device for air conditioners includes a dialectric housing having a pair of terminals separately mounted therein. A metal connector plate is also mounted within the housing and is tempered so as to. bend when exposed to a predetermined temperature from a normal position wherein it engages both of the terminals and completes the electric connection therebetwecn to an open circuit position wherein it is free from electrical contact with at least one of the terminals. At least one catch is provided on the housing and is adapted for retentively engaging and holding the connector plate in its open circuit position in response to movement of the connector plate to this position. The catch is movable out of retentive en-' gagement with the connector plate, but is urged into retentive engagement by a spring. A reset mechanism is connected to the catch and is adapted to urge the catch out of retentive engagement with the connector plate in response to manual manipulation. The protective device includes means for mounting it upon the casing surrounding an air conditioner compressor and electric motor, and is adapted to sense the heat emanating from the compressor and motor. The terminals of the protective device are connected in series with a power source and the electric motor so that upon sensing a predetermined temperature the protective device breaks the circuit between the power source and the electric motor.
7 Claims, 6 Drawing Figures l PROTECTIVE DEVICE FOR AIR CONDITIONERS This invention relates to air conditioning equipment and more specifically to a protective device for preventing the burning out of the compressor motor when the equipment is not functioning properly. levels Air conditioners presently include a compressor driven by an electric motor and adapted to compress coolant fluid from a gas to a fluid. The fluid is forced from the compressor through a series of coils where it changes from a fluid to a gas thereby causing the coils to be cooled. The vaporized fluid is then returned to the compressor where it is again compressed into a fluid and recycled through the coils. After extended use air conditioning equipment sometimes develops a defect. A great majority of these defects result in a build up of temperature in the compressor. Occasionally community sources of electrical power fail to maintain constant voltage leverls and this fluctuation often causes heat build up in the compressor. Excessive heat in the compressor ultimately causes the moving parts of the compressor to bind and become immoveable. After the compressor becomes frozen solid the motor will quickly burn out as it tries to drive the immoveable compressor. v
On presently known air conditioning equipment protective devices have been provided for sensing the build up in temperature in the compressor whenever a defect occurs in the equipment. When this temperature reaches a predetermined point the present protective devices break the circuit between the power source and the electric motor, thereby shutting off the motor and compressor. Many of these protective devices include a bimetal plate which bridges the distance between two separate terminals. When the heat reaches a predetermined temperature the bimetal plate bends and separates from at least one of the contacts, thereby breaking the circuit between the electric motor and the power source. However, when the compressor cools down after it has been shut off the bimetal plate returns to its original position thereby closing the circuit again and actuating the motor. If the defect in the equipment still exists the compressor will again heat up, the bimetal plate will again break the circuit, and the motor will again be shut off. This alternative opening and closing of the circuit will continue indefinitely, until either the compressor breaks down or the motor burns out. By the time the owner of the air conditioning equipment realizes something is wrong, the damage has already been done.
Many air conditioning manufacturers have utilized two thermostats such as described above. One of the thermostats senses the temperature inside the compressor and the other senses the temperature outside the compressor. Usually the external thermostat is adapted to break the circuit at a lower temperature than the internal thermostat. However, the use of dual thermostats does not alleviate the problem referred to above because they still permit recycling until the motor burns out.
The present invention provides a circuit breaking device which includes a catch adapted to prevent the metal contact from returning to its original position once it has broken the circuit. A reset button and mechanism are provided for releasing the metal plate and permitting it to return to its closed circuit position.
Thus the protective device of this invention does not recycle until a repairman has had an opportunity to repair the defect in the equipment.
Therefore a principal object of the present invention is the provision of a protective device which will shut off an air conditioning compressor when the compressor is overheating.
A further object of the present invention is to provide a protective device which will not recycle and which must be manually reset once it shuts off the compressor.
A further object of the present invention is the provision of a protective device which can be easily mounted on the outside of a compressor or compressor casing for sensing unusual heat from the compressor and responding thereto by shutting ofi the compressor.
A further object of the present invention is the provision of a protective device which can be easily adapted to any brand of compressor without necessitating the redesign of the compressor.
A further object of the present invention is the provision of a protective device which can be manually reset merely by pushing a button.
A further object of the present invention is the provision of a protective device which eliminates the need for both an internal and an external thermostat.
A further object of the present invention is the provision of a protective device which is simple in construction, economical to manufacture, and durable in use.
These and other objects will be apparent to those skilled in the art.
This invention consists in the construction, arrangements, and combination of the various parts of the device, whereby the objects contemplated are attained as hereinafter more fully set forth, specifically pointed out in the claims, and illustrated in the accompanying drawings in which:
FIG. 1 is a perspective view of the protective device of this invention; FIG. 2 is a sectional view taken along line 2-2 of FIG. 1 and showing the warped disc in its normal position;
FIG. 3 is a sectional view similar to FIG. 2 and showing the warped disc in its circuit breaking position;
FIG. 4 is a sectional view taken along line 4-4 of FIG. 2 and showing the disc in its normal position;
FIG. 5. is a sectional view similar to FIG. 4 and showing the disc in its circuit breaking position; and
FIG. 6 is a schematic view illustrating the interrelation of the various components of this invention.
Referring to the drawings, a protective device 10 includes a housing 12 including a closed end 16 and an open end 18. Housing 10 forms a substantially cylindrical cavity 20. Extending downwardly as viewed in FIG. 3 within cavity 20 are two terminal mounts 22 and 24 which have electrical terminals 26 and 28 mounted on their lower ends. Connected to each terminal 26 and 28 is an electrical lead 30 comprising an electrical connector 32 and a prong 34 mounted on the outer surface of housing 12. Prongs 34 are adapted to be connected to electrical wire 36 leading to an electrical power source.
Surrounding open end 18 of housing 12 is an annular rim 38. Annular rim 38 abuts against a heat conducting member 40 which includes a securing bracket thereon for engaging annular rim 38, thereby attaching housing 12 to heat conducting member 40. Extending through closed end 16 of housing 12 is a threaded bore 42 which is in approximate registeredalignment with the cylindrical axis of cavity 20. Positioned radially outwardly from threaded bore 42 and extending through closed end 16 is a smooth bore 44. Extending through housing 12 into the lateral cylindrical walls of cavity 20 is a pair of catch openings 46 which are oppositely positioned so that they face one another across cavity 20.
A connector plate 48 includes a warped disc 50 which is circular in configuration and which includes a threaded post 52 extending axially from its approximate center. Threaded post 52 is threadably secured within threaded bore 42, and supports warped disc 50 within cylindrical cavity 20 with the lateral edges of warped disc 50 being adjacent catch openings 46. Mounted on the upper surface of warped disc 50 are a pair of contact points 54 which are in registered alignment with terminals 26 and 28. This registered alignment is provided by virtue of a notch 56 in the edge of disc 50 and a rib 58 on the internal wall of housing 12 which is slidably fitted within notch 56 so as to permit disc 54 to move axially within cavity 20 while at the same time preventing rotational movement of disc 50 therein. Disc 50 is made of a tempered steel which expands and contracts at varying rates throughout its thickness. In its normal position disc 50 is concave on its upper surface (FIGS. 2 and 4) with contacts 54 engaging terminals 26 and 28. However, when exposed to a predetermined temperature, adapted to bend until it pops and reverses its concave configuration so that it is concave downwardly (FIGS. 3 and In this position contacts 54 are spaced from terminals 28 thereby creating a circuit breaking position for disc 50. Disc 50 may be tempered so that it will reverse itself at any predetermined temperature desired. The predetermined temperature will be determined by the particular type of equipment being used with protective device and the maximum temperature at which the equipment can operate satisfactorily.
A pair of catches 60 each include a spring arm 62 and a catch block 64. Spring arms 62 are operatively secured at one of their ends to the outer surface of housing 12 and support catch blocks 64 within catch openings 46. Catch blocks 64 protrude into cavity and include a catch lip 66 adjacent their lower ends. Catch lip 66 is formed by a downwardly presented shoulder 68. Extending upwardly from catch lip 66 is a slanted caming surface 70 which extends upwardly and radially outwardly. Catch blocks 64 are moveable radially outwardly with respect to the cylindrical axis of cavity 20 by virtue of their mounting on spring arms 62.
The reset mechanism 72 includes a first pair of links 74, a second pair of links 76, and an actuating member 78 having a reset button 80 on its upper end. Links 74 and 76 are each hinged at one end to one of catch blocks 64 and are hinged together at their opposite ends to form a hinged joint 82 located intermediate catch blocks 64. Because the combined length of links 74 and 76 is slightly greater than the distance between catch blocks 64, links 74 and 76 form an angle less than 180 degrees at hinged joint 82. At the lower end of actuating member 78 is a yoke 84 which is pivotally joined into hinged joint 82. Links 74 and 76 act as a toggle linkage so that depression of button 80 causes hinged joint 82 to move downwardly thereby spreading catch blocks 64 away from one another. While links 74 and 76 are each shown in pairs, they may also be limited to single links without detracting from the invention.
The arrangement of catch blocks 64 in relation to warped disc 50 is such that catch lips 66 protrude slightly inwardly beyond the peripheral edges of disc 50. In its normal position (FIGS. 2,4) the upper surface of disc 50 is concave and its outer edges are positioned above catch lips 66. When heat increases beyond a predetermined point disc 50 bends and reverses its concave shape to that shown in FIGS. 3,5. As disc 50 moves to this circuit breaker position its outer edges cam catch blocks 64 radially outwardly until its edges are positioned below catch lips 66. As the outer edges of disc 50 move below catch lips 66, catch blocks 64 snap inwardly and catch lips 66 engage the upper surface of the outer edges of disc 50, thereby preventing disc 50 from returning to its normal position. In order to release disc 50 so that it can return to its normal position one must depress actuating member 78 so as to cause catch blocks 64 to spread apart. Disc 50 is then free to snap back to its original normal position shown in FIGS. 2, 4.
Referring to FIG. 6, an air conditioning unit 86 is shown schematically. An electric motor 88 is shown drivingly connected to a compressor 90. Motor 88 and compressor 90 are enclosed within a casing 92 which is formed from a good heat conducting material such as steel. Protective device 10 is operatively mounted on casing 92 so that disc 50 is in a position to be exposed to heat emanating from casing 92. Terminals 26 and 28 are shown connected in series with motor 88 and an electrical power source 94. Compressor includes a pressure outlet 96 and a vacuum inlet 98. A conduit 100 extends from pressure outlet 96 through a fluid cooling coil 102 and a connecting conduit 104 leads from coil 102 to a vaporizing coil 106. In vaporizing coil 106 the cooling fluid is transformed from a liquid to a gas and this change in state of the fluid causes vaporizing coil 106 to cool. Vaporizing coil 106 is the coil normally located within the furnace of a central air conditioning unit. Leading from vaporizing coil 106 is a return conduit 108 which is connected to vacuum inlet 98 of compressor 90.
During normal operation of air conditioning unit 86 motor 88 drives compressor 90 forcing fluid through conduit 100, cooling coil 102, connecting conduit 104, vaporizing coil 106, return conduit 108 and back into vacuum inlet 98. During this normal operation disc 50 is in its normal position (FIGS. 2 and 4) wherein contact points 54 engage terminals 26 and 28 and provide electrical connection therebetween. When a defect occurs somewhere in air conditioning unit'86, the result is usually a pressure build up within compressor 90. For example, an improperly functioning cooling coil 102 will cause such a pressure increase. As the pressure increases the heat within compressor 90 also increases. This heat is conducted through casing 92 and is ultimately transferred to disc 50. When disc 50 is heated to its predetermined point it reverses its concave configuration, thereby moving to its circuit breaking position. When disc 50 moves to its circuit breaking position it breaks the circuit from power source 94 to motor 88, thereby shutting down motor 88 and compressor 90. As
compressor 90, motor 88, casing 92, and disc 50 cool there is a tendency for disc 50 to return to its normal position. However, catch lips 66 of catch blocks 64 prevent discv 50 from returning to its normal position and completing the circuit between temiinals 26 and 28. Thus when a defect occurs in air conditioning unit 86, the unit soon shuts down and will not recycle into a running state. The shutting down of the unit will be a warning to the owner of the unit that a repairman should be called. The repairman can come, locate the defect and correct it before pushing reset button 80 and releasing disc 50 so that it can return to its normal position.
Catches 64 may be mounted in a number of different ways but should be spring mounted so that they will be urged radially inwardly toward the edge of disc 50. Likewise the structure of reset button 80 and links 74 and 76 may vary without detracting from the invention. Any mechanism for urging catch block 64 away from the edges of disc 50 will be satisfactory. While a circular warped disc 50 is shown in the drawings this disc may be replaced by a bimetal strip which is permanently secured to one of terminals 24 or 26 and which is moveable in response to application of heat away from the other of terminals 24 or 26. Protective device is adapted to be mounted in a number of places in the air conditioning unit. It is illustrated as being connected to housing 92, but it may also be connected to any part of the air conditioning unit where it can be exposed to heat emanating from the compressor.
From the foregoing it can be seen that protective device 10 will shut off an air conditioning compressor the moment that the compressor begins to overheat. Furthermore, the protective device will not permit the compressor to recycle indefinitely once it has been shut off. Instead it will shut off once and not come on again until reset button 80 is depressed. The simplicity of protective device 10 is such that it can be mounted in any of a number of positions on a compressor and may also be mounted upon any make or design of compressor without requiring a redesign thereof. While protective device 10 can be mounted on any presently existing compressing units without changing the design of these units, it eliminates the need for both the internal and external thermostats presently being used thereon. Therefore it simplifies and makes less expensive the manufacture of presently known air conditioning compressors.
Protective device 10 is shown in the drawings as being used with a 110 volt circuit, but it can be used equally as well in a 220 volt circuit. Furthermore the particular location of protective device 10 in the circuitry of the air conditioner can vary without detracting from the invention. The only requirement for successful operation is that protective device 10 be capable of causing the compressor to shut down once the compressor begins to overheat. For example, instead of being wired directly into the compressor motor circuit, protective device 10 can be wired into a 24 volt room temperature thermostat circuit so that it will cause the thermostat to shut off the compressor when the compressor overheats. Thus it can be seen that the device accomplishes at least all of its stated objectives.
Some changes may be made-in the construction and arrangement of my PROTECTIVE DEVICE FOR AIR CONDITIONERS without departing from the real spirit and purpose of my invention, and it is my intention to cover by my claims any modified forms of structure or use of mechanical equivalents which may be reasonably included within their scope.
1. In combination:
a dielectric housing;
a pair of terminals separately mounted within a said housing, each of said terminals having a lead adapted to be connected to an electrical power source;
a warped concave disc having opposite edges and being adapted to reverse its concave configuration in response to a predetermined temperature from a normal position wherein it engages both of said terminals and completes electrical connection therebetween to an open circuit position wherein it is free from electrical contact with at least one of said terminals;
at least two catches on said housing and being positioned adjacent said opposite edges of said disc, said catches being movable toward said opposite edges of said disc for retentively engaging and holding said disc in said open circuit position, said catches being movable away from said opposite edges for releasing said disc;
bias means urging said catches toward said edges of said disc;
manually movable mechanism for moving said catches away from said opposite edges of said disc. 2. In combination:
a dielectric housing;
a pair of terminals separately mounted within said housing;
a warped concave disc having a peripheral edge and being adapted to reverse its concave configuration in response to a predetermined temperature from a nonnal position wherein it engages both of said terminals and completes electrical connection therebetween to an open circuit position wherein it is free from electrical contact with at least one of said terminals;
at least one catch on said housing, said catch being movable from a first position wherein at least a portion thereof protrudes inwardly beyond said peripheral edge of said disc to a second position wherein said catch clears said peripheral edge of said disc;
bias means urging said catch toward said first position;
said catch being free to move to said first position when said disc is in said open circuit position whereby said catch will retentively engage said disc and hold said disc against movement to said normal position; and
mechanism for manually moving said catch to said second position.
3. A combination according to claim 1 wherein said disc includes a post extending axially from its approximate center, said post being operatively secured to said housing.
4. A combination according to claim 1 wherein said mechanism includes two links and an actuating member, said links each having one end hinged to one of said catches, said links also being hinged together at a hinged joint between said catches and forming an angle less than 180 therebetween at said hinged joint;
' said actuating member being manually moveable to entherein having an open end and a closed end, said terminals being within said cavity; said disc having opposite faces and being mounted within said cavity with one of said faces facing said closed end and the other of said faces facing said open end.
6. A combination according to claim 5 wherein said tenninals engage said one face of said disc when said disc is in its normal position.
7. A combination according to claim 6 wherein said housing includes means thereon for securing said housing to a heat conducting member with said open end presented towards said heat conducting member so as to expose said disc to heat being conducted through said heat conducting member.