Abstract:
An equalizing tank is disclosed comprising a housing, a pressure dissipation orifice, and a return flow line configured to provide fluid communication within the housing without fluid entering the pressure dissipation orifice. Also disclosed is a method of making the equalizing tank and an automotive air-conditioning system including the equalizing tank.

Description:
CROSS-REFERENCE TO RELATED PATENT APPLICATIONS  
         [0001]    This application claims the benefit and priority of related German Patent Application 10059369.0 filed on Nov. 29, 2000, which is incorporated by reference herein in its entirety.  
         BACKGROUND OF THE INVENTION  
         [0002]    A. Field of the Invention  
           [0003]    The invention relates to an equalizing tank, in particular, to an equalization tank for use in a cooling-medium circuit of an air-conditioning system of a motor vehicle and having pressure-equalizing means for equalizing an excessive and/or negative pressure.  
           [0004]    B. Background of the Invention  
           [0005]    Equalizing tanks in fluid circuits of motor vehicles, for example, in an engine cooling circuit, require a pressure relief valve and a suction relief valve in order to not lose any cooling liquid during acceleration or deceleration of the vehicle, and to equalize changes in liquid volume of the engine cooling circuit, for example, due to changes in temperature or due to loss of cooling liquid.  
           [0006]    Valves of this type represent a cost factor and generally have to be fitted on the equalizing tank in separate installation steps during production, which is disadvantageous. Thus, a need exists for a valve-free equalization tank that does not lose cooling liquid during acceleration or deceleration, and equalizes changes in liquid volume.  
         SUMMARY OF THE INVENTION  
         [0007]    The present invention is directed to overcoming or at least reducing the effects of one or more of the problems set forth above and other problems in the prior art.  
           [0008]    According to one aspect of the invention there has been provided an equalizing tank suitable for use in an automotive air-conditioning system that includes a fluid cooling-medium circuit, comprising: a housing defining a generally closed tank for containing the cooling-medium fluid; a pressure compensation mechanism comprising a pressure dissipation orifice that opens into the housing, wherein the orifice remains open; and structure associated with the housing that prevents the cooling-medium fluid from entering the pressure dissipation orifice during changes in fluid level within the housing.  
           [0009]    According to one aspect of the present invention, an equalizing tank is provided comprising a housing, a pressure dissipation orifice, and a return flow line configured to provide fluid communication within the housing without fluid entering the pressure dissipation orifice.  
           [0010]    According to another aspect of the present invention, the return flow line is positioned within a receiving depression of the housing.  
           [0011]    According to another aspect of the present invention, the housing includes a first end and a second end, wherein the return flow line provides fluid communication between the first end and the second end of the housing.  
           [0012]    According to another aspect of the present invention, the housing comprises a plurality of wall-like depressions protruding into the interval volume of the housing, the depressions defining a first, second, and third subvolume within the housing, a first gap providing fluid communication between the first subvolume and the second subvolume, and a second gap providing fluid communication between the second subvolume and the third subvolume.  
           [0013]    According to a preferred aspect of the present invention, the equalizing tank further comprises a collection container, wherein the return flow line discharges into the collection container.  
           [0014]    According to another aspect of the present invention, the return flow line is an integral part of the collection tank.  
           [0015]    According to another preferred aspect of the present invention, the pressure dissipation orifice is positioned above a point at which the return flow line discharges into the collection container.  
           [0016]    According to another aspect of the present invention, the equalizing tank further comprises a fluid-level gage.  
           [0017]    According to yet another aspect of the present invention, a method of manufacturing an equalizing tank is provided comprising blow-molding a housing, the housing being formed with an opening and a receiving depression; inserting a collection container into the housing opening, the collection container including a pressure dissipation orifice; and inserting a return flow line into the receiving depression, wherein the return flow line provides fluid communication with the collection container and within the housing in a manner such that fluid does not enter the pressure dissipation orifice during changes in fluid level in the housing.  
           [0018]    According to another aspect of the present invention, the method of manufacturing an equalizing tank further comprises inserting a fluid-level gage into the housing, the fluid-level gage being positioned in fluid communication with the collection container.  
           [0019]    According to yet another aspect of the present invention, a method of equalizing the amount of pressure in an air-conditioning circuit is provided comprising maintaining a pressure equalization tank in fluid communication with the circuit; retaining fluid heat exchange medium within the pressure equalization tank, the tank having a first end and a second end; equalizing pressure within the tank via a pressure dissipation orifice that remains open; and flowing the fluid between the first end and the second end via a return flow line without fluid entering the pressure dissipation orifice in response to changes in fluid level in the tank.  
           [0020]    According to another aspect of the present invention, the method of equalizing the pressure of fluid further comprises restricting fluid flow within the housing through gaps in depressions protruding into the internal volume of the housing.  
           [0021]    According to another aspect of the present invention, the method of equalizing the pressure of fluid further comprises discharging fluid from the return flow line into a collection container.  
           [0022]    According to another aspect of the present invention, the method of equalizing the pressure of fluid further comprises measuring the fluid-level within the tank with a fluid-level gage, the fluid-level gage comprising a circular receptacle adapted to receive a sensor, and a float surrounding at least a portion of the receptacle, wherein the fluid level gage is in fluid communication with the collection container.  
           [0023]    According to yet another aspect of the present invention, a vehicular air-conditioning system is provided comprising a primary circuit, and an air-conditioning device that includes a stationary air-conditioning function. The primary circuit comprises a compressor, a condenser, an evaporator, and a plurality of refrigerant lines providing fluid communication between the compressor, condenser and evaporator. The stationary air-conditioning device is coupled to the first circuit via the evaporator, and comprises a cold store, a heat exchanger, an equalizing tank, and a plurality of cooling medium lines providing fluid communication between the cold store, heat exchanger, and equalizing tank. The equalizing tank comprises an equalizing tank as described above.  
           [0024]    Further objects, features and advantages of the invention will become apparent from the detailed description of preferred embodiments that follows, when considered together with the accompanying figures of drawing. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0025]    In the drawings:  
         [0026]    [0026]FIG. 1 shows a schematic block diagram of an exemplary air-conditioning system of a motor vehicle having a stationary air-conditioning function according to the present invention,  
         [0027]    [0027]FIG. 2 shows a cross section of an equalizing tank according to an embodiment of the present invention,  
         [0028]    [0028]FIG. 3 shows a perspective view of an equalizing-tank housing according to an embodiment of the present invention,  
         [0029]    [0029]FIG. 4 shows a perspective view of a return flow line having a collecting tank according to an embodiment of the present invention, and  
         [0030]    [0030]FIG. 5 shows a perspective view of a housing part of a fluid-level gage according to an embodiment of the present invention. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0031]    Reference will now be made in detail to presently preferred embodiments of the invention. Wherever possible, the same reference numbers will be used throughout the drawings to refer to the same or like parts.  
         [0032]    It is an object of the invention to provide an improved equalizing tank which is constructed as simply as possible and is therefore correspondingly cost-effective to manufacture, and which can be used in particular in a cooling-medium circuit of an air-conditioning system of a motor vehicle.  
         [0033]    The invention relates to an equalizing tank, in particular, to an equalization tank for a cooling-medium circuit of a motor vehicle air-conditioning system. The equalization tank is provided with pressure-equalizing means for equalizing an excessive and/or negative pressure. In order to provide an improved equalizing tank, which is constructed as simply as possible and is therefore correspondingly cost-effective to manufacture and which can be used in particular in a cooling-medium circuit of an air-conditioning system of a motor vehicle that includes a stationary operating function (i.e., that operates also when the vehicle is stationary and not running), it is proposed that the pressure-equalizing mechanism is formed by an unclosed opening and that a mechanism is provided, by means of which the fluid is prevented from emerging out of the opening. Air-conditioning systems including a stationary operating function preferably comprise an additional circuit, in which, for example, a special cooling medium, that will be used for cooling, is able to be cooled if the primary circuit is stopped.  
         [0034]    The equalizing tank according to the invention has pressure-equalizing means which is formed, according to the invention, by an unclosed opening, a mechanism additionally being provided for preventing the fluid from emerging out of the opening. Pressure release valves and/or suction relief valves can thereby be omitted in a cost-effective manner, since any excessive pressure or negative pressure can be equalized through the unclosed opening.  
         [0035]    In a structurally simple and cost-effective design of the invention, the mechanism is formed by a return flow line which connects one end of the equalizing tank to the other, so that the fluid within the tank is essentially guided in a circuit during movements of the equalizing tank, the opening being arranged in such a manner that the fluid is guided past the opening, with the result that it cannot emerge through the opening.  
         [0036]    In one preferred embodiment of the invention, the return flow line can have at its downstream end a collection container which has the opening advantageously arranged above a point at which the return flow line discharges into the collection container.  
         [0037]    For the purpose of simple and cost-effective installation, the return flow line can be designed integrally with the collection container, and/or as a separate insert part.  
         [0038]    A fluid-level gage is advantageously arranged in the equalizing tank in order to be able to find out the current fluid level. The fluid-level gage can be equipped with a signal transmitter which emits a corresponding warning signal if the fluid level is too low.  
         [0039]    In a cost-effective manner, the equalizing tank can be produced in a blow-molding process, and the fluid-level gage and the return flow lines can be inserted into the molded equalizing tank during installation.  
         [0040]    According to the invention, the equalizing tank can be used in a cooling-medium circuit of an air-conditioning system of a motor vehicle having a stationary air-conditioning function.  
         [0041]    An equalizing tank  10  according to the invention can be part of an air-conditioning system  12  of a motor vehicle, shown schematically in FIG. 1, which may contain a stationary air-conditioning function. The air-conditioning system  12  has a primary circuit  14 , in which a compressor  18 , a condenser  20 , an expansion element  22  and an evaporator  24  are connected via cooling-agent (refrigerant) lines  16 . A secondary circuit  26  is coupled to the primary circuit  14  via the evaporator  24 . In the secondary circuit  26 , a cooling medium, for example a water/glycerol mixture, is guided in the circuit via a pump  28  and is cooled in the evaporator  24 . Coupled to the secondary circuit  26  via a four-way valve  30 , is a heat exchanger  32  in which air  34  to be supplied to a vehicle interior can be cooled. Similarly, a cold store  36  can be coupled to the secondary circuit  26  via a four-way valve  38 , in order to make stationary air-conditioning possible. Changes in volume of the cooling medium in the secondary circuit  26  and excessive and negative pressures in the secondary circuit  26  are equalized by the equalizing tank  10 . An air-conditioning system of this type is disclosed in U.S. Pat. No. 6,112,543, which is incorporated by reference herein in its entirety.  
         [0042]    FIGS.  2  to  5  illustrate an exemplary embodiment of the equalizing tank  10  and its components in detail. The equalizing tank  10  has a housing  40  which is preferably produced in a blow-molding process. A connecting stub  44  is arranged in a side wall  41 , in the region of a bottom  42  of the housing  40 , in order to connect the equalizing tank  10  to the secondary circuit  26 . The internal volume  46  in this preferred embodiment is divided virtually into three subvolumes  52 ,  54  and  56  by depressions  58 ,  60  and  62  which protrude in the manner of walls into the internal volume  46  and leave a gap in each case only at their side edges and/or ends. Two of the gaps are illustrated with the reference numbers  48  and  50 . The gaps between the side walls of the equalizing tank  10  and the side edges of depressions  58 ,  60 ,  62  cannot be seen in this illustration. On account of the wall-like depressions  58 ,  60 ,  62 , the fluid can not slosh to and fro in an unobstructed manner in the interior volume  46  during movements of the equalizing tank  10 ; rather, it can only pass from one subvolume into another via the gaps. As a result, sloshing noises are substantially avoided.  
         [0043]    A fluid-level gage  66  is arranged in the subvolume  52  situated in front, as seen in the direction of travel  64 . The fluid-level gage  66  has the fluid-level gage housing  68 , which is illustrated in FIG. 5, and has a connecting adapter  70 , for connecting the fluid-level gage  66  to the equalizing tank  40 . Connected to the connecting piece  70  is a cup-like receptacle  72  into which a sensor (not illustrated) can be introduced, with the aid of which the position of a float  74  surrounding the receptacle  72  (FIG. 2) and therefore the fluid height H can be determined. The sensor may, for example, be a reed switch. There is furthermore connected to the connecting piece  70  a connecting stub  76  through which the fluid can flow, as will be explained in greater detail below.  
         [0044]    The front subvolume  52  is connected to the rear volume  56 , as seen in the direction of travel  64 , via a return flow line  78 . The return flow line  78 , which is illustrated in FIG. 4, has, at its end facing the rear subvolume  56 , a connection  80  for connection to the rear subvolume  56  and, at its front end, a collecting tank  82  with a connecting line  85  arranged on its bottom, which can be plugged onto the connecting stub  76  of the fluid-level gage  66 . In its upper end region, the collecting tank  82  has an unclosed opening  84  which, when the equalizing tank is installed, is situated higher than the point at which the line  78  discharges into the collection container  82 .  
         [0045]    As can be seen from FIG. 3, the fluid-level gage  66  and the collecting tank  82  can be arranged in recess  86 , located in a corner region of the equalizing tank  10 , the fluid-level gage  66  being inserted first during the installation, and then the return flow line  78  with the collecting tank  82  is inserted and connected. In order to receive the return flow line  78 , the tank  10  has a receiving depression  88  on its upper side.  
         [0046]    During operation of the air-conditioning system  12  and of the vehicle, the equalizing tank  10  functions as follows.  
         [0047]    In the normal state, the equalizing tank  10  is filled approximately as far as the filling height H. Any excessive pressure or negative pressure can be dissipated without any problem via the opening  84 . When the vehicle accelerates in the direction of travel  64 , the fluid will flow through the gaps past the depressions  58 ,  60 ,  62  into the rear subvolume  56 , and if the acceleration is very great and long-lasting, the fluid can flow via the return flow line  78  and the collection container  82  and the connecting line  85  back into the first subvolume  52 , so that the fluid is, as it were, guided in the circuit via the return flow line  78  without losing fluid. Since the opening  84  is situated higher than the point at which the return flow line  78  discharges into the collecting tank  82 , the fluid cannot emerge out of the opening  84 . In the case of negative acceleration, i.e., braking of the vehicle, the fluid in the first subvolume  52  could rise. If, in the event of very severe deceleration, the fluid rises to a sufficient extent that the collection container  82  is filled, the fluid is, if appropriate, guided via the return flow line  78  into the rear subvolume  56 , in which case the fluid will not emerge out of the opening  84 , since this opening is situated higher than the point at which the return flow line  78  discharges into the collecting tank  82 .  
         [0048]    An equalizing tank is therefore provided which does not have any pressure release valves or suction release valves, and which can nevertheless equalize an excessive pressure or negative pressure and any changes in volume which may arise, for example, from changes in the temperature of the fluid or due to any freezing of the fluid.  
         [0049]    The foregoing description of a preferred embodiment 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 form disclosed, and modifications and variations are possible in light of the above teachings or may be acquired from practice of the invention. The embodiments were chosen and described in order to explain the principles of the invention and its practical application to enable one skilled in the art to utilize the invention in various embodiments and with various modifications as are suited to the particular use contemplated. It is intended that the scope of the invention be defined the claims appended hereto and that the claims encompass the disclosed embodiments and their equivalents.