Patent Application
20140117103
This invention generally relates to thermostats for appliances such as refrigerators or freezers and particularly to housings for thermostats.
Thermostats for appliances such as refrigerators or freezers are used to control a compressor that adjusts the temperature of the temperature controlled environment of the appliance, e.g. where the food or other product is stored. The thermostat typically includes a housing, a temperature sensor assembly, a switching arrangement, and an adjustment mechanism for adjusting when the thermostat will turn on and/or turn off a compressor for adjusting the temperature within the temperature controlled environment.
Due to increasing costs of manufacturing and materials, it is desired to provide for simplified assembly and reduced component costs. Embodiments of the present invention provide improvements over the current state of the art of thermostats.
Embodiments of the invention aim to provide a new and improved thermostat that reduces the number of components and/or reduces the cost of assembly and manufacturing.
In one embodiment, the new and improved thermostat utilizes a new and improved housing that reduces part cost and assembly costs. In a particular embodiment, a thermostat including a housing, a temperature sensor assembly, a switching arrangement and an adjustment shaft is provided. The housing includes a generally L-shaped main body attached to a generally U-shaped cover to define an internal cavity. The L-shaped main body and U-shaped cover will form a generally cube shaped housing that is easily assembled and manufactured to reduce part costs. The temperature sensor assembly includes a bellows operably fluidly attached to a capillary tube. The bellows and capillary tube define a sealed cavity storing a working fluid that will drive the bellows due to changes in the temperature of the working fluid. The switching arrangement is operably actuated by the temperature sensor assembly to open and close a circuit as a result of changes in temperature of the working fluid. By opening and closing the circuit, a compressor can be turned on and off to adjust the temperature of the temperature controlled environment. The adjustment shaft is configured to adjust a temperature set point at which the temperature sensor assembly actuates the switching arrangement. The adjustment shaft extends through the housing.
In a particular embodiment, the U-shaped cover includes a first side portion, a second side portion and a base portion. The first and second side portions are operably coupled to one another by the base portion to form the U-shape with an opening formed between the first and second side portions. The L-shaped main body includes a bellows plate portion and a first leg portion that extends at an angle relative to the bellows plate portion, typically about a ninety degree angle. When assembled, the housing defines a generally open side that is opposite the side provided by the bellows plate portion.
In one embodiment, the first and second side portions extend outward from an inner surface of the base portion and define free distal edges that are spaced away from the base portion. In an assembled state, the first leg portion of the main body is positioned adjacent the free distal edges of the first and second side portions and a free distal edge of the bellows plate portion is positioned adjacent the base portion.
In one embodiment, each of the first and second side portions includes at least one connecting tab extending from a first edge that extends between the free distal edge and the base portion of corresponding side portion. The bellows plate portion includes a corresponding aperture configured to receive a corresponding one of the connecting tabs therethrough. In the assembled state, the connecting tabs are plastically bent inward and over an outer surface of the bellows plate portion to secure the main body to the cover.
In one embodiment, the thermostat further includes a switch base attached to the housing adjacent the open side of the housing. Each of the first and second side portions of the cover includes at least one switch base connecting tab extending from a second edge, opposite the first edge. The switch base includes a corresponding connecting lug for each of the switch base connecting tabs. The connecting lugs extend outward from corresponding sides of the switch base. In the assembled state, the switch base connecting tabs are plastically bent around the corresponding connecting lugs to secure the switch base to the housing.
In one embodiment, each side portion of the cover includes at least one laterally outward extending locating tab that tapers outward when moving in a direction extending away from the base, an end of the locating tabs being farthest from the base portion of the cover defining an abutment for locating the housing during installation.
In one embodiment, the base portion includes an embossed region that extends laterally outward and away from the distal free edges of the side portions. The embossed region defines an aperture through which the adjustment shaft extends and in which the adjustment shaft is rotatable about an adjustment shaft axis. The embossed region includes a laterally inward extending projection. The adjustment shaft includes a radially outward extending tab that extends radially outward beyond the inward extending projection. The tab of the adjustment shaft angularly abutting the laterally inward extending projection at a limit of the rotation of the adjustment shaft relative to the cover.
In one embodiment, the cover includes a pair of mounting wings. The mounting wings extend laterally outward beyond edges of the side portions. The mounting wings are configured to cooperate with an attachment mechanism, e.g. a screw, bolt, clip, etc. to secure the thermostat to an appliance, and typically within an opening in a panel of the appliance.
In one embodiment, at least one of the side portions includes a laterally outward offset ground terminal formed therein. The ground terminal is a continuous piece of material with the rest of the corresponding side portion. Typically, the cover and the main body will be formed from stamped sheet metal.
In one embodiment, the bellows portion includes bent reinforcement flaps forming opposed edges of the bellows plate portion that extend away from the leg portion of the main body. The reinforcement flaps are spaced laterally apart from one another a distance greater than the first and second side portions of the cover. The first and second side portions of the cover being received between the reinforcement flaps when the housing is in an assembled state such that each reinforcement flap overlaps the outer surface of the adjacent one of the first and second side portions.
In another embodiment, a thermostat including a housing, a switching arrangement, a temperature sensor assembly, and an adjustment shaft is provided. The switching arrangement is configured to open and close a circuit. The temperature sensor assembly includes a bellows operably fluidly attached to a capillary tube. The bellows and capillary tube define a sealed cavity storing a working fluid, typically a gas. The temperature sensor assembly is configured to actuate the switching arrangement as a result of changes in temperature of the working fluid. The adjustment shaft is configured to adjust a temperature at which the temperature sensor actuates the switching arrangement. The adjustment shaft extends through the housing. The adjustment shaft includes a recess defining a radially inward facing cam surface that bounds the recess. The radially inward facing cam surface has a varying radius relative to a rotational axis of the adjustment shaft. The switching arrangement includes a cam follower that cooperates with the cam surface to adjust a temperature setting at which the temperature sensor actuates the switching arrangement.
In one embodiment, the adjustment shaft includes an enlarged portion that is sized larger than an aperture in the housing through which the adjustment shaft extends. The enlarged portion has a top surface that abuts an inner surface of the housing surrounding the aperture. The recess of the adjustment shaft that receives the cam follower of the switching arrangement is formed through an opposite end of the enlarged portion.
In one embodiment, the adjustment shaft includes a reduced diameter cylindrical portion axially offset from the enlarged portion along the rotational axis. The reduced diameter cylindrical portion is sized to mate with the aperture through the housing.
In one embodiment, the thermostat further includes a bush beaded to the cover. The adjustment shaft extending through the bush. The bush includes an enlarged cylindrical portion that is sized larger than an aperture in the housing through which the adjustment shaft extends. This portion abuts an outer surface of the housing. The bush includes an axially extending annular flange that extends through the aperture in the housing. When assembled, the axially extending annular flange is beaded radially outward and over an inner surface of the housing adjacent the aperture to secure the bush in the aperture in the housing.
In one embodiment, the bush further includes a second axially extending cylindrical portion that is on an opposite side of the bush as the axially extending annular flange. The adjustment shaft includes a circular recess. The second axially extending cylindrical portion is radially inwardly beaded into the circular recess of the adjustment shaft to axially secure the adjustment shaft within the bush.
In one embodiment, an inner surface of the housing adjacent the aperture through which the adjustment shaft extends includes a plurality of recesses. The axially extending annular flange engages the recesses during the beading process.
In one embodiment, the thermostat further includes a driver operably attachable to the adjustment shaft. The driver is configured to be attached to the adjustment shaft in more than one angular orientation about the rotational axis of the adjustment shaft. The driver is configured to engage a knob and to translate rotation motion of the knob to the adjustment shaft.
In one embodiment, a method of assembly a thermostat is provided. The method includes attaching a U-shaped cover to an L-shaped main body to form a housing; securing an adjustment shaft to the housing for rotation; attaching a temperature sensor assembly to the housing; attaching, operably, a switching arrangement to the housing and the temperature sensor assembly such that the temperature sensor assembly actuates the switching arrangement in response to sensed changes in temperature; and connecting the switching arrangement to the adjustment shaft in such a manner that rotation of the adjustment shaft adjusts the temperature at which the temperature sensor assembly actuates the switching arrangement.
In one embodiment, the adjustment shaft includes a recess bound by a radially inward directed cam surface. The cam surface has a varying radius relative to a rotational axis of the adjustment shaft. The switching arrangement includes a cam follower. The step of connecting the switching arrangement to the adjustment shaft includes inserting the cam follower into the recess and biasing the cam follower into contact with the cam surface such that rotation of the adjustment shaft adjust the position of the cam follower as well as a temperature setting of the thermostat.
In one embodiment, the U-shaped cover includes a first side portion, a second side portion and a base portion. The first and second side portions are operably coupled to one another by the base portion to form the U-shape with an opening formed between the first and second side portions. The L-shaped main body includes a bellows plate portion and a first leg portion that extends at an angle relative to the bellows plate portion. When assembled, the housing defines a generally open side that is opposite the side provided by the bellows plate portion. The first and second side portions extend outward from the base portion and define free distal edges. Each of the first and second side portions includes at least one connecting tab extending from a first edge that extends between the free distal edge and the base portion of the corresponding side portion. The bellows plate portion includes a corresponding aperture configured to receive a corresponding one of the connecting tabs therethrough. The step of attaching a U-shaped cover to an L-shaped main body to form a housing includes inserting the connecting tabs into the apertures formed in the bellows plate portion; plastically bending the connecting tabs inward and over an outer surface of the bellows plate portion to secure the main body to the cover, with the first leg portion of the main body being positioned adjacent the free distal edges of the first and second side portions. A free distal edge of the bellows plate portion is positioned adjacent the base portion.
Other aspects, objectives and advantages of the invention will become more apparent from the following detailed description when taken in conjunction with the accompanying drawings.
The accompanying drawings incorporated in and forming a part of the specification illustrate several aspects of the present invention and, together with the description, serve to explain the principles of the invention. In the drawings:
While the invention will be described in connection with certain preferred embodiments, there is no intent to limit it to those embodiments. On the contrary, the intent is to cover all alternatives, modifications and equivalents as included within the spirit and scope of the invention as defined by the appended claims.
With additional reference to
With reference to
An adjustment shaft 116 extends through an aperture 118 formed in the embossed region 112. The embossed region 112 includes an inward extending protection 122 that forms a stop. The adjustment shaft 116 includes a radially outward extending tab 120 that will contact the inward extending projection to limit the rotation of the adjustment shaft 116 relative to the cover 102. A retaining clip 124 engages the adjustment shaft 116 to secure the adjustment shaft 116 to the cover 102.
With primary reference to
Each side 130, 132 includes a pair of outward stamped locating tabs 136 that are designed to be flexible coupling tabs for securing the cover 102 and the thermostat 100 to a panel of the appliance in which the thermostat 100 is installed. The tabs will allow for snap mounting of the cover 102 to the panel.
With reference to
The cover 102 includes two pentagonal shaped apertures 144, one in each side 130, 132. Each aperture 144 terminates in a corner 146. The pentagonal shaped apertures 144 receive corresponding pivot portions 148 of the bellows lever 150 (see e.g.
The cover 102 also includes, prior to assembly, four axially extending switch base connecting tabs 166 that extend from the opposite edges of sides 130, 132 as connecting tabs 138. Switch base connecting tabs 166 are bent during assembly of the thermostat 100 (see
With primary reference to
A sensor assembly 180 (see
With reference to
The bellows plate portion 140 also includes bent reinforcement flaps 188. The bent reinforcement flaps 188 are spaced laterally from one another a distance substantially equal to the width of between outer surfaces of the side portions 130, 132 of the cover 102 such that the side portions 130, 132 will mount in between the reinforcement flaps 188 when the thermostat is fully assembled. The reinforcement flaps 188 will substantially overlap the outer surface of the adjacent one of the side portions 130, 132 when assembled. The reinforcement flaps 188 are bent at approximately a ninety degree angle relative to the bellows plate portion 140. The apertures 142 formed in the bellows plate portion 140 for receiving the connecting tabs 138 of the cover 102 being formed in the bend between the main portion of the bellows plate portion 140 and the bent reinforcement flaps 188.
The bellows plate portion 140 also includes an aperture for receipt of a tool to access an adjustment screw for setting the thermostat 100.
The bellows 108 is formed from a flexible and ductile metallic material. With primary reference to
The opposite end of the bellows 108 is an open end 202. The open end 202 is designed to mate with and against the circular stamping 182 of the bellows plate 140. The open end 202 is typically joined to the bellows plate 140 with a ring of solder, or glue, not shown. The solder or glue joins the capillary tube 106 to the bellows plate 140 and bellows 108 to couple the three components in a sealed configuration to seal the working fluid within the cavity formed by these components. Typically, the working fluid is a refrigerant, tetrafluorethane type, known as R134A, propane, known as R290, propylene, known as R1270, or any other fluid that has a temperature v. pressure relationship appropriate for the temperature range of operation of the thermostat 100.
The capillary tube 106 is preferably made of metallic material with good thermal conductivity such as copper, aluminum, or copper clad aluminum (CCA). An open end of the capillary tube 106 is axially received in the capillary tube receiving tube 186 of the circular stamping 182. The capillary tube 106 includes a cylindrical collar 204 that serves as a stop to limit the axial insertion of the capillary tube 106. After assembly a retaining collar, not shown, may be attached to the end of the capillary tube that is on the inside of the bellows plate 140 to further prevent removal of the capillary tube 106 from the bellows plate 140. The opposite end of the capillary 106 is sealed after filled with the working fluid.
With reference to
The lever 156 includes a threaded hole 212 that receives adjustment screw 214. The lever 156 also includes a clearance hole 216 that allows for adjustment of a further adjustment screw within the thermostat. The lever 156 defines a cutout region 218 to allow passage of the bellows 108. The lever 156 includes two side leg portions 220 with two extruded pivot portions 154 that fit into cut-outs 152 of the sides 130, 132 of the cover 102 (see e.g.
With reference to
The retaining clip 124 is made of flexible metal material and has cut out tabs 710 disposed on its inner surface and with a proper slope so that it fits into a circular recess 712 made in the adjustment shaft 116. The cylindrical portion 700 includes tab 120 designed to serve as a stop against turning when it engages inward extending projection 122 of the cover 102 as discussed above. The cylindrical portion also has a recess 750 that is bounded by variable radiused inner cam surface 208 that functions as a cam that cooperates with the tab 206 of lever 156. Here, the tab 206 of lever 156 is received axially into recess 750 of the adjustment shaft 116. Spring blade 232, discussed more fully below, biases lever 156, and particularly tab 206 against inner cam surface 208. Angular adjustment of the adjustment shaft 116 by rotation about its axis of rotation adjusts the position of lever 156 by rotating lever 156 about pivot portions 154.
A tongue 224 projecting axially from the cylindrical portion 700 configured to push a stamped region 222 of bellows lever 150 when the adjustment shaft 116 rotates in a given direction of rotation until abutting the stop 122 provided by cover 102.
The configuration described above for the adjustment shaft 116 is preferred because it has fewer components and is easier to assemble in the thermostat 100, resulting in a lower project cost, but may also have other configurations.
In
In
These additional adjustment shafts 2116, 2118 would have the same features for engagement with the switching arrangement of the thermostat.
The central bush 2400 includes a second axially extending cylindrical portion 2420, located on top of cylindrical portion 2410 which is beaded into a circular recess 2422 of the shaft 2416 which serves to secure the adjustment shaft 2416.
Bush 2400 includes a central hole 2430 to allow passage of adjustment shaft 2416. To help in fixing the bush 2400 to the cover 102, small recesses 2440 (see
If necessary, a mechanism to avoid turning the thermostat with respect to the appliance panel where it will be installed may be provided. This mechanism can be done through a tongue 2450 made in an extension of the cover 102 (see
With reference to
A spring blade 232 is riveted to the bellows lever 150. The spring blade 232 is formed from a metallic material with a spring characteristic, i.e. hardness and mechanical strength appropriate to have a flexibility when a force is applied near its end. The thickness can vary to achieve a distinctive spring rate in order to achieve different ranges of operating temperature for the thermostat. The spring blade 232 cooperates with the adjustment screw 214 that is carried by lever 156.
The L-shaped actuator 228 is formed from a plastic material that has high mechanical strength and good electrical insulation, such as polyacetal. The Actuator 228 includes a first portion 236 that receives tab 226 and a second portion 238 that extend generally perpendicular to that first portion that touches a tab 240 of blade 242.
With reference to
Blade 242 is made of a metallic material of good electrical conductivity and also of good mechanical strength, such as a phosphor bronze, beryllium copper or the like. The blade 242 is preferably flat and is generally shaped like a letter Q. With reference to
The electrical contact 258 is made of a good electrical conductor, such as silver or silver alloy, and has a cylindrical shape with its contact surface slightly spherical. The contact 258 includes a reduced diameter shank configured to fit through the semi-circular cutouts 256 of the blade 242 and hole 264 of the bridge 262 for attachment. The bridge 262 is made of good electrical conductor material, preferably a copper alloy such as brass or phosphor bronze, and has two side wings 266 to engage the boss 260 of the blade 242. It also has the aforementioned hole 264 for receiving the cylindrical region of the contact 258 for attachment. An alternative blade 242′ is illustrated in
With reference to
The process of fixing the contact 258 and bridge 262 on the blade 242 occurs as follows. It is necessary to apply a force on the blade 240 in the direction indicated by arrows 274 (see
The motion of the distal ends of the side arms 252 including the attached contact 258 and bridge 262 is limited by adjustment screw 278 (see e.g.
With reference to
Terminal 272 is also preferably made of a copper alloy like brass, with good electrical conductivity. Terminal 272 includes an extension 286 that extends to the outside of the switch base 170 and is designed to connect to the grid of the appliance where the thermostat 100 is used. While not shown, this terminal 272 has a tongue similar to tongue 282 of the prior terminal 250 to mount the terminal 272 to the switch base 170. Terminal 272 has a hole 270 for receiving contact 268.
Terminals 250 and 272 can also have their extensions 280 and 286 positioned at the other end thereof.
The switch base 170 is made of plastic material of high mechanical strength and good electrical insulation, preferably of the type polyamide (nylon) or polyester, but not limited to these and may have mineral or fiberglass load to improve the appropriate properties. The switch base 170 has the shape of a box with one side open to interact with other parts of the thermostat 100. As noted above, the switch base 170 also has four (4) connecting lugs 168 that are generally rectangular or square with two located on each side that cooperate with the switch base connecting tabs 166 of the cover 102 by staking. The switch base 170 also a plurality of rectangular configured to receive the extensions 280, 286 of the terminals 250, 272. The switch base 170 may also include side ribs (not shown), which also have the function of separating the terminals to obtaining an electrical safe distance between the terminals.
The above description is for the basic version of the thermostat of the present invention.
With reference to
With reference to
To prevent this from happening, this embodiment provides a barrier 400. Barrier 400 is mainly composed of an insulator preferably made of electrical insulation material, and is essentially a flat plate and may contain a reinforcement flange 404 along its periphery to obtain good mechanical strength. The barrier 400 may include a hole 408 in its central region for passage guidance of actuator 410. This barrier 400 may also have a tear 412 in one of its corners to enable the passage of one component from another version and also serves to prevent the assembly of this component in the switch base in another position, beyond the normal. This barrier 400 fits perfectly, without gaps, within the switch base 170 (see
Terminal 500 has one end forming an angle of approximately 90 degrees with the portion extending out of the switch base 170. This angled portion caries an auxiliary contact 502. An auxiliary blade 504 is made of a material with good electrical conductor and good flexibility to act as a spring, as is the case of phosphor bronze or beryllium copper. It has in one of its ends a hole 506 designed to be secured by staking to the terminal 250.
The other end of auxiliary blade 504 carries a second auxiliary contact 512. The middle of the blade 504 can include bends to make it more flexible and to adapt to the relative position between the portion of the terminal 250 where the auxiliary blade 504 is attached and the location of the auxiliary contact 502 carried by terminal 500. This auxiliary blade 506 may also have a bended area 520 to make the area where the second auxiliary contact 512 is attached more rigid.
This version includes an auxiliary actuator 530 designed to fit in the tear 412 discussed in the prior embodiment. The actuator 530 slides in tear 412. The actuator 530 also has an extension 532 which is configured to reach the blade 504 and to separate contacts 502, 512, resulting in the opening of the auxiliary switch. Displacement of the actuator 530 is provided by the tab 120 of the adjustment shaft 116 (illustrated in
With reference to
Tab 240 of blade 242, when pressed by the actuator 228 to the right, i.e. away from bellows 108, causes, when blade 242 reaches the trigger point, the distal ends of side arms 252 carrying contact 258 to snap to the left. This action closes the circuit by causing contact 258 to engage contact 268. This is the situation represented in
The end not shown of the capillary tube 106 is located at the point of temperature control. So a temperature variation in the control point will change the pressure of the control fluid (i.e. a gas) contained within the capillary tube 106 and bellows 108, following the curve of temperature versus pressure corresponding to the gas used. When forces are balanced due to the bellows 108 and blade 244 for a desired temperature, the bellows lever 150 will be in an intermediate position. When the gas pressure decreases (lower point temperature control) the bellows 108 will decrease its pressure on the tab 196 of the bellows lever 150. The force of blade 244 will then act on screw 230 causing the bellows lever 150 to rotate in a counterclockwise direction about pivot point A. This shift will occur until tab 240 of the contact blade 242 goes beyond its tipping point and then the firing of the side arms 252 of the blade 242 happens in the opening direction to disconnect the contacts 258, 268. In the
Adjustment screw 214 is adjusted so that its tip touches blade 232 before the snap action of the contact blade 242 occurs. The opening of the contacts 258, 268 causes the shutdown of the cooling system compressor, causing the temperature of the controlled environment to increase. When the temperature of the working fluid increases, the bellows 108 will press with increased force against tab 196 of bellows lever 150, causing it to move in a clockwise direction.
Because of this clockwise movement of the bellows lever 150, the blade 232 will do the same movement, because it is attached to said bellows lever 150. The screw 214 is adjusted so that the blade 232 will no longer be in contact with the screw 214 before the snap action phenomenon of the contact blade 242 occurs. The gas pressure of the working fluid continues to increase until the moment when the tab 240 of the contact blade 242 exceeds its equilibrium point and the side arms 252 of the contact blade 242 perform a snap action to the left of
The above explanation occurs for a given angular position of the adjustment shaft 116. When the shaft 116 is rotated to another position, the varying radius of the inner cam surface 208 changes the angular position of the lever 156, because curved end portion 210 (also referred to as “curved portion 210”) rests against the cam surface 208. This movement of lever 156 will cause the screw 214 to press the blade 232 more or less, depending on the direction of rotation of the adjustment shaft 116. This blade 232 acts on the screw 214 only when the temperature to be controlled is decreasing, i.e., only when the bellows lever 150 is to the left in
The temperatures at which the cut in and the cut out events occur can be adjusted through screw 230, when it is desired to increase or decrease both temperatures, closing and opening of contacts, and through the adjustment screw 278 when it is desired to increase or decrease the differential, which is the difference between the cut in and cut out temperatures. The rotation of screw 278 causes the changes in the cut in temperature, without affecting the cut out temperature. Once the cut in and cut out temperatures of the thermostat 100 for a given position of the adjustment shaft 116 are determined, the end user of the appliance can regulate the temperature of the controlled ambient by rotating the adjustment shaft 116.
Usually rotating the adjustment shaft 116 clockwise causes the temperature to become colder and turning it in a counterclockwise direction causes the temperatures to become warmer. This is achieved because rotating adjustment shaft 116 clockwise causes the curved portion 210 of lever 156 which is in contact with the cam surface 208 of variable radius circular portion 700 of the adjustment shaft 116, moves to the right in
Rotating the adjustment shaft 116 in a counterclockwise direction will cause the curved portion 210 of lever 156 to move to the left, resulting in lower force of the blade 232 on screw 214, which means that the balance of forces is give at a greater value, resulting in warmer temperature for the cut out. Optionally, the variable radius of the cam surface 208 of adjustment shaft 116 may have the varying radius reversed, such that rotating adjustment shaft 116 in a clockwise direction causes the cut out temperature of the thermostat be warmer, and turning in the counterclockwise causes the cut out temperature to become colder. This range of adjustment for cut out temperature with the rotation of the adjustment shaft 116 can vary by using different profiles for the cam surface 208 of the adjustment shaft 116, combined with different spring rate for the blade 232 and also with the use of different gases inside the capillary tube 106. With this procedure we can get the correct temperatures for the desired application.
In the embodiment with “alarm,” the principle of operation of the thermostat is above, with the addition of this “alarm” function, which consists in the fact that if the temperature exceeds a predetermined amount beyond the cut in temperature for a given position of the adjustment shaft 116 without the thermostat switch on, then the extra movement that the bellows lever 150 makes to the right (with reference to
For embodiments with an extra terminal to an auxiliary switch (e.g.
This is called an “off” position, because in this position of the shaft 116 all the electrics, both between the terminals 250 and 272 and between terminals 250 and 500 will open the contacts, or be disconnected. This extra pair of contacts is used for connecting, for example, an electrical resistance normally used on the door of a refrigerator and used to heat said door in order to avoid condensation of air humidity on the outer surface of said door. Said condensation can occur due to thermal insulation of this part of the refrigerator being not as efficient when compared with the thermal insulation on the other walls of the refrigerator. The electrical resistance must always be ‘on’ when the operation of the refrigeration appliance, in this case a refrigerator, and must be switched off only when you want to shut down the entire unit, which is done via a rotating shaft of the thermostat until “off” position. It is also possible to connect an electrical resistance in the evaporator of a refrigerator, for certain conditions, so that resistance is on whenever the compressor is off, and is off when the compressor is on.
This is achieved by connecting this resistor in parallel with the terminals 250 and 272. Thus when the compressor is working, i.e. when the contacts 258 and 268 are closed, the electrical resistance between them is much smaller than the ohmic resistance of the resistor from the evaporator, then the electric current will pass through the pair of contacts and the resistor will not work. When the contacts open, then the current will start to pass through the resistor. In this case the auxiliary switch will help to cut out this resistor, when the shaft is placed in said “off” position. For this to happen, the electric power should be connected to terminals 272 and 500.
In the case of the resistor coupled to the electrical switch inside the thermostat, its function is to heat the region of the sensor element. It is known that this concept of a thermostat with expansion fluid has the property of controlling the temperature in the coldest portion of the sensing element. That's because the pressure of the gas contained inside the sensor element is corresponding to the coldest temperature of the whole system. In some applications, depending on the location of the body's thermostat, especially when installed inside the refrigeration appliance, the ambient temperature where the thermostat's body is located can be colder than the capillary tube, which is the control area. Using this resistor 600 (see
This thermostat 3000 includes adjustment lever 3156 that is typically stamped metal plate or engineered plastic. The adjustment lever 3156 includes tab 3206 that is a cam follower that cooperates with variable radius cam surface 208 of shaft 116. Again, tab 3206 preferably includes a curved surface that cooperates with cam surface 208 of shaft 116.
Adjustment lever 3156 includes pivot portions 3154 that are mounted in circular cut-outs 3152 formed in cover 102 for rotation about axis C. The pivot portions 3154 are attached to two lateral bended tabs 3155.
Spring blade 3244 is affixed at one end to lever 3156, typically by a rivet, and is biased against adjustment screw 230 carried by bellows lever 150. Rotation of shaft 116 will change the radius of cam surface 208 against which tab 3206 is pressed causing adjustment lever 3156 to rotate about axis C. Rotation of adjustment lever 3156 about axis C adjusts the amount of force that spring blade 3244 will apply to bellows lever 150 via adjustment screw 230. By adjusting the amount of force that adjustment lever 3156, and particularly spring blade 3244, applies to the bellows lever 150, the cut-in and cut-out temperatures of the thermostat 3000 are adjusted.
An inward folded tab 3157 (see
In
With this motion, the actuator 228 attached to bellows lever 150 will also move in a similar direction until blade 242 reaches its tipping point. This will cause the side arms 252 of blade 242 to trigger in the opposite direction until contact 258 touches adjustment screw 278 and opening contacts 258, 268 shutting down the compressor.
With the compressor off, the temperature of the environment sensed by capillary tube 106 will begin to rise, which increases the gas pressure within the capillary tube 106 and bellows 108. The bellows lever 150 will begin to move in the opposite direction illustrated by arrow 3201, overcoming the force of spring blade 3244. The actuator 228 will displace central tab 240 of blade 242 until it exceeds its equilibrium point. At this moment, the side arms 252 shoot in the direction of arrow 3200, i.e. left in
The temperature at which these events of opening and closing of the contacts 258, 256 can be adjusted through adjustment screw 230, when it is desired to simultaneously increase or decrease both temperatures, i.e. the cut out and the cut in temperatures. Adjustment of adjustment screw 278 will adjust the differential between the cut-out and cut-in temperatures. Rotation of adjustment screw 278 adjusts the cut-in temperature, without affecting the cut-out temperature. Once the temperatures of the cut-in and cut-out temperatures of the thermostat 3000 have been determined for a given position of the shaft 116, the end user of the appliance can regulate the controlled temperature by rotating the shaft 116.
Typically, rotating shaft 116 clockwise causes the temperatures to become colder and turning the shaft 116 counter-clockwise causes the temperatures to become warmer. This is achieved because rotation of shaft 116 clockwise causes tab 3206 of the adjustment lever 3156 that is in contact with the variable-radius cam surface 208 of shaft 116, moves to the right (i.e. in the direction illustrated by arrow 3201 in
Rotating shaft 116 in the counter-clockwise direction, i.e. the opposite direction will get opposite results and will correspond to a higher temperature for both the cut-in and cut-out events.
Optionally, the cam surface 208 of shaft 116 could vary in radius in the opposite direction to reverse the operation discussed above. Further, the range of temperature variation can be varied by varying the profile of cam surface 208. Further variation can be provided by varying the spring rates of spring blade 3244 as well as varying the gases inside the capillary tube 106 and bellows 108. With these procedures, a correct temperature profile can be obtained for desired applications without requiring significant variations in the configuration of the thermostat 3000.
All references, including publications, patent applications, and patents cited herein are hereby incorporated by reference to the same extent as if each reference were individually and specifically indicated to be incorporated by reference and were set forth in its entirety herein.
The use of the terms “a” and “an” and “the” and similar referents in the context of describing the invention (especially in the context of the following claims) is to be construed to cover both the singular and the plural, unless otherwise indicated herein or clearly contradicted by context. The terms “comprising,” “having,” “including,” and “containing” are to be construed as open-ended terms (i.e., meaning “including, but not limited to,”) unless otherwise noted. Recitation of ranges of values herein are merely intended to serve as a shorthand method of referring individually to each separate value falling within the range, unless otherwise indicated herein, and each separate value is incorporated into the specification as if it were individually recited herein. All methods described herein can be performed in any suitable order unless otherwise indicated herein or otherwise clearly contradicted by context. The use of any and all examples, or exemplary language (e.g., “such as”) provided herein, is intended merely to better illuminate the invention and does not pose a limitation on the scope of the invention unless otherwise claimed. No language in the specification should be construed as indicating any non-claimed element as essential to the practice of the invention.
Preferred embodiments of this invention are described herein, including the best mode known to the inventors for carrying out the invention. Variations of those preferred embodiments may become apparent to those of ordinary skill in the art upon reading the foregoing description. The inventors expect skilled artisans to employ such variations as appropriate, and the inventors intend for the invention to be practiced otherwise than as specifically described herein. Accordingly, this invention includes all modifications and equivalents of the subject matter recited in the claims appended hereto as permitted by applicable law. Moreover, any combination of the above-described elements in all possible variations thereof is encompassed by the invention unless otherwise indicated herein or otherwise clearly contradicted by context.
