Patent Application
20050011218
The present invention relates generally to temperature control systems for multi-compartment refrigerators, and more particularly to dampers and damper control systems for regulating the temperature of multi-compartment refrigerators having, e.g. fresh food, crisper, and freezer compartments.
In a typical multi-compartment refrigerator there are several methods for controlling the temperature of each of the compartments. It is common practice for the refrigeration system, i.e. the compressor, evaporator, fan, etc., to directly cool the freezer compartment. Air from the freezer compartment is directed to the fresh food compartment by means of an opening from the freezer to the fresh food compartment. Air is throttled in this opening by means of some type of air damper control. The damper has traditionally been a manually operated mechanism, which can be adjusted by the user to vary the freezer temperature. The fresh food temperature is generally controlled by a thermostat which senses the fresh food compartment temperature. The thermostat governs the operation of the compressor and evaporator fan. The resulting freezer temperature is a function of the fresh food compartment set point temperature and the position of the manual damper. It is generally known that this type of control system is not ideal for temperature stability of the freezer, especially when the outside temperature changes and the fresh food set point temperature is changed. The advantage of this system is that it is very inexpensive to produce.
A less traditional means of control used currently in only approximately 15% of standard refrigerators produced in the United States is to cycle the compressor using a thermostat that senses the freezer temperature. The air flow to the fresh food compartment is attenuated by a modulating air damper control. This control uses a refrigerant charged bellows that expands and contracts in response to the temperature of the fresh food compartment. The bellows movement is then used to drive a door, located in the air flow stream, to attenuate air flow to the fresh food compartment. The movement of the door is very predictable, thus allowing this device to be offered on a production basis. This type of control system allows for more accurate temperature control for both compartments than the method described above. Outside temperature variance and door openings are better compensated using this system.
The principal drawback for such a system is cost. Manufacturers positioning certain product as “high performance” are the users of this type of system. Further, despite the improved efficiency of this more expensive system, the controlled temperature of both compartments still varies over a substantial range of temperatures. This is due to the passive nature of both of these control functions, which is characterized by greater operating tolerances as well as limited response time. Another problem of such a damper system, which also plagues the less expensive systems, is icing of the damper door. The buildup of ice on the damper door can prevent proper operation of the temperature control. Such ice buildup may result in the damper door being prohibited from opening or closing, thus upsetting the normal control of temperature in both compartments.
The growing use of microcontroller and microprocessor based controls in residential appliances now makes them cost effective for use in residential refrigerators. They provide increased control accuracy, faster response, and lower refrigeration cycle times, all of which result in higher efficiency and lower operating costs to the consumer. Within these electronic control type systems, however, there remains a need for mechanical damper assemblies. To further improve the operating efficiency of the electronic controls these mechanical damper assemblies must preferably be capable of operating in a gated manner; i.e. in an open/closed sequence at a given duty cycle, as determined by the electronic control. The ideal damper assembly therefore must itself be capable of fast response as well as efficient air flow characteristics.
One such mechanical damper system that overcomes the problems existing with the prior systems is disclosed in U.S. Pat. No. 6,240,735, to Kolson et al., entitled ROTARY DAMPER ASSEMBLY, and assigned to the assignee of the instant application, the teachings and disclosure of which is hereby incorporated in their entireties by reference thereto. Advantageously, this patent discloses a rotary damper assembly for controlling the flow of a fluid. The rotary damper assembly includes inner and outer hollow cylinders, each having one or more side wall apertures. The inner cylinder is nested within the outer cylinder in a manner to permit relative axial rotation of the cylinders about a common longitudinal axis. This inner cylinder receives the fluid flow at an axial inlet. The flow of fluid out of the assembly is in a radial direction through the side wall apertures. The size of the opening formed by the side wall apertures is proportional to the degree of alignment of the cylinder apertures.
While the Kolson et al. rotary damper assembly provides a great advance over the prior damper systems, overcoming many of the problems existing therewith, it is designed to control the flow of fluid between two compartments. However, high end, specialty, and newer refrigerator models being designed today include multiple compartments to store fresh food. A crisper drawer or compartment inside the main fresh food compartment is one such example. While present models typically allow a user to manually set a damper between the main fresh food compartment and the crisper drawer, such temperature control suffers from the very problems that lead to the use of controlled dampers between the freezer and the fresh food compartment, e.g. wide temperature variances. This problem is especially acute with the crisper drawer or compartment as its frequency of being opened compared to the main refrigerator door of the fresh food compartment is much less. However, the temperature control is generally driven by the fresh food compartment temperature. As such, the crisper drawer may become over chilled, which may damage vegetables and fruits stored therein.
The Kolson et al. rotary damper also requires a directional change in the fluid flow through the assembly. That is, the Kolson et al. damper redirects the flow of the fluid from an axial flow to a radial flow therein. This results in increased fluid turbulence, which reduces the efficiency of the fluid exchange between the two compartments. Refrigerator manufacturers are very concerned about power consumption, and are very competitive in reducing power consumption. They are also under tremendous pressure from the Department of Energy to make incremental power consumption reductions. As such, any improvements in the efficiency of any aspect of the refrigerator is highly sought after.
Therefore, there continues to exist a need in the art for a damper system that provides better temperature stability of all of the temperature controlled compartments of a refrigerator, including the freezer compartment, the fresh food compartment, and the crisper drawer or compartment, while reducing the cost and power consumption and increasing the overall efficiency of the system.
In view of the above, the present invention provides a new and improved rotary damper assembly. More particularly, the present invention provides a new and improved rotary damper assembly that provides temperature control for the freezer and multiple fresh food compartments, each of which may be maintained at different temperatures. Further, the present invention provides a new and improved rotary damper assembly that increases the efficiency of fluid flow by providing essentially laminar flow therethrough.
One feature of the present invention is improved efficiency of fluid transfer through the damper assembly. A further feature of the present invention is selectable and gated operation between a full open and a full closed position to allow variable fluid flow between selected compartments.
According to the present invention, a damper assembly for controlling the flow of a fluid includes concentric inner and outer hollow cylindrical members, the inner cylindrical member being adapted to receive and direct the fluid flow and to be nested within the outer cylindrical member in a manner which permits relative axial rotation of the members about a common longitudinal axis. In one embodiment, each member has side wall apertures for providing a fluid flow path therethrough, whereby the flow of fluid through the assembly is proportional to the degree of alignment of the apertures. In an alternate embodiment, the inner cylindrical member includes flow control members forming a flow path therethrough in relation to the side wall apertures of the outer cylindrical member. In another embodiment, the cylinders also include an end aperture at a longitudinal end thereof for providing another or an alternate fluid flow path therethrough. The apertures are so arranged such that selectable flow through the apertures may be achieved.
In further accord with the present invention, the inner cylinder includes fluid sealing members disposed thereon which restrict the fluid flow path through the assembly to the side wall apertures. In still further accord with the present invention the fluid sealing members are disposed circumferentially along each longitudinal end of the inner cylinder and axially along a length of the cylinder.
In yet still further accord with the present invention, the damper assembly includes a source of rotational motive power which is adapted to engage with and rotate the inner cylindrical member relative to the outer cylindrical member. The source of motive power is selectably actuated to rotate the inner cylindrical member to establish a degree of registration of the apertures as necessary to provide a desired amount of fluid flow through the assembly to the desired compartment(s). In yet still further accord with the present invention the outer cylindrical member is stationary relative to axial rotation of the inner cylindrical member. In yet still further accord with the present invention, the damper assembly includes a position control device which de-actuates the source of motive power in response to the rotational position of the inner cylindrical member at one or more selected locations corresponding to a desired relative positioning of the side and/or end wall apertures. In still further accord with the present invention, the source of motive power provides full slew axial rotation of the inner cylindrical member between a full flow position corresponding to substantial registration of the cylindrical side and/or end wall apertures, and a minimum flow position corresponding to no overlap of any portion of the apertures.
The rotary damper assembly of the present invention provides high efficiency and selectable modulation of fluid flow through the assembly and is highly suitable for use with different electronic flow control applications, including refrigeration equipment. This efficiency is achieved through the dual cylindrical member configuration which provides slew rates which are compatible with gated operation as well as good fluid seal characteristics in the full closed position. Increases in efficiency are realized through the essentially laminar fluid flow through the assembly between the main compartments between which the assembly is installed.
Other features 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:
a-c are simplified fluid flow diagrams illustrating fluid flow paths through the embodiment of the rotary damper of
a-d are simplified fluid flow diagrams illustrating fluid flow paths through the embodiment of the rotary damper of
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.
Turning now to the drawings, an exploded isometric illustration of an embodiment of the flow through rotary damper of the present invention is provided in
The housing 12 also preferably includes inlet and outlet plenums 20, 22 that allow for flush mounting of the assembly 10 between two flat wall portions such as may exist between the fresh food compartment and the freezer compartment of a refrigerator. Further, these plenums 20, 22 may be contoured to fit a particular installation for the rotary damper assembly 10, and are not constrained to any particular configuration. Indeed, one skilled in the art will recognize that these plenums 20, 22 may be separate and apart from the cylindrical outer body member 14 depending on the installation requirements.
The flow through rotary damper assembly 10 of the present invention also includes a cylindrical inner body member 24, which is inserted into and rotatably accommodated within the cylindrical outer body member 14. The cylindrical inner body member 24 includes a plurality of longitudinal fluid sealing members 26 and circumferential fluid sealing members 28 that cooperate with the inner surface 30 of the cylindrical outer body member 14 to prevent or restrict the ability of fluid to flow through the assembly 10 between the outer 14 and inner 24 body members.
The cylindrical inner body member 24 also defines inlet and outlet apertures 32, 34 in the sidewalls thereof. In a preferred embodiment, these two apertures 32, 34 are aligned in proximity with one another such that fluid flowing into one of the apertures may continue to flow without direction change out of the other aperture. As discussed above, this greatly increases the efficiency of the flow through rotary damper of the present invention over prior rotary dampers that required the fluid flow to change direction within the assembly. Also as discussed above, if the location of apertures 16, 18 is varied from this most efficient orientation, the location of apertures 32, 34 may also be reoriented to allow for the two sets of apertures to come into alignment when fluid flow through the assembly is desired.
The cylindrical inner body member 24 may also include location control cam surfaces 36, 38 that cooperate with a position sensing control mechanism, such as microswitch 40, to provide position feedback information to the rotary damper control. Such control may utilize simple cutoff circuitry that cuts the power to the source of rotational mode of power, such as motor 42 when the desired damper position has been reached, or may utilize more sophisticated electronic control to allow variable orientation between the two sets of apertures 16/18 and 32/24 to provide variable flow through control within the assembly 10. As will be recognized by those skilled in the art, more or fewer location control cam surfaces may be employed to provide multiple position sensing and control of the position of the cylindrical inner body member 24 relative to the cylindrical outer body member 14. Additionally, one skilled in the art will recognize that the location control cam surfaces 36, 38 may be dispensed with entirely if other location control mechanisms are utilized. For example, if motor 42 is a timer motor, that self regulates its running time, the position of the cylindrical inner body member 24 may be controlled via timing as opposed to actual position sensing. Additional position control mechanisms may also be employed as are well known in the art such as, the inclusion of a shaft encoder, etc. The particular choice of location control mechanisms is not a limiting factor in the present invention. Further, the motor 42 may also embody a stepper motor or a DC motor. As is apparent from the forgoing and the following, the motor 42 may be unidirectional or bi-directional.
As may be seen from the end view illustration of
The selectable flow control provided by the flow through rotary air damper of the present invention, and in particular with regard to the embodiment of the present invention illustrated in
a illustrates an orientation of the cylinder inner body member 24 relative to the cylindrical outer body member 14 that provides for fluid transfer between, for example, the freezer compartment, the fresh food compartment, and a chiller drawer on a multi-compartment refrigerator. The cylindrical inner body member 24 is driven to this relative position when both the main fresh food compartment and the chiller drawer require cooling from the freezer compartment. As will be understood by those skilled in the art, the relative sizing of the apertures 32, 34 in relation to the aperture 50 allows the proper amount of chilled air to flow into the various compartments in relation to their size and overall cooling requirements. In this way, the chiller drawer is not overcooled to the point where damage to the fruits and vegetables typically stored therein will occur.
In an exemplary installation in a refrigerator having a freezer compartment, a main fresh compartment, and a chiller drawer or compartment that is sealed within the main fresh food compartment, the orientation of the cylindrical inner body member 24 relative to the cylindrical outer body member 14 will typically be as illustrated in
When no compartment requires cooling, the cylindrical inner body member 24 is rotated until the apertures 32, 34 are no longer in alignment with apertures 16, 18 of the cylindrical outer body member 14 to block all flow of air through the assembly 10. From the position illustrated in
Turning now to the flow illustrations of
If only the main fresh food compartment of the refrigerator requires cooling, the cylindrical inner body member 24 may be rotated within the cylindrical outer body member 14 such that its orientation is as illustrated in
If the chiller compartment temperature were to rise above its temperature set point, the cylindrical inner body member 24′ would be rotated relative to the cylindrical outer body member to a position as illustrated in
If neither of the fresh food compartments require cooling, the cylindrical inner body 24′ is rotated in relation to the cylindrical outer body member 14 until its orientation is as illustrated in
As will be apparent to those skilled in the art from the preceding discussion, the embodiment of the present invention illustrated in
A further alternate embodiment of the flow through rotary air damper 10 of the present invention is illustrated in
Fluid flow through this embodiment of the flow through rotary damper 10 is illustrated in
A further alternate embodiment is illustrated in
All of the references cited herein, including patents, patent applications, and publications, are hereby incorporated in their entireties by reference.
The foregoing description of various embodiments of the invention has been presented for purposes of illustration and description. It is not intended to be exhaustive or to limit the invention to the precise embodiments disclosed. Numerous modifications or variations are possible in light of the above teachings. The embodiments discussed were chosen and described to provide the best illustration of the principles of the invention and its practical application to thereby enable one of ordinary skill in the art to utilize the invention in various embodiments and with various modifications as are suited to the particular use contemplated. All such modifications and variations are within the scope of the invention as determined by the appended claims when interpreted in accordance with the breadth to which they are fairly, legally, and equitably entitled.
