Abstract:
A regulating valve for a heat-transferring medium has a valve member controllable primarily by an electrical actuating member, but in the event of failure of the electrical actuating member, a thermostatic actuating member, operating independently of the electrical actuating member and of electric power, is provided in order to prevent damage to the system by driving the valve member when a predetermined temperature is exceeded.

Description:
CROSS-REFERENCES TO RELATED APPLICATIONS  
       [0001]    This application claims the benefit of German patent application number 10053699.9, filed Oct. 25, 2000, incorporated herein by reference. 
     
    
     
       FIELD OF THE INVENTION  
         [0002]    The invention relates to a valve system for regulating a heat-transferring system, in which the valve member can be adjusted by means of an electrical actuating member.  
         BACKGROUND OF THE INVENTION  
         [0003]    Regulating valves of this kind are frequently employed in cooling circuits in which it is desirable to maintain a system temperature within a range of tolerable operating temperatures. The electrical actuating member drives the valve member through a range varying from fully closed to fully open in order to adjust the amount of coolant flowing through the circuit and to maintain a system temperature within a preferred range. The electrical actuating member may be controlled through various means, including thermostatically, manually, or through automatic computer control. Valve systems of this type are well known in the art and take many different forms depending on the particular type of flow regulation needed.  
           [0004]    The principal drawback of these systems, however, is in the potential for loss of control over the electrical actuating member. Such a loss of control might occur for a number of reasons, such as loss of electrical current, damage to the drive motor, failure of an automatic control, loss of communication between control and drive, or some other defect in the system. The loss of control may lead to a system temperature in excess of the tolerance of the system, which in turn leads to damage either to the cooling system itself or to the object to be cooled. It is therefore desirable to employ a system through which it is possible to drive the valve independently of any electrical energy source.  
         OBJECT AND SUMMARY OF THE INVENTION  
         [0005]    It is accordingly an object of the invention to provide a regulating valve for a heat transferring system which will substantially avoid faulty operation even in the event of a loss of electrical current or errors in the transmission of control signals. A more specific object is to provide a regulating valve that is primarily adjustable by means of an electric drive, but comprises a secondary, failsafe, non-electric drive that prevents faulty operation or, at a minimum, mitigates its effects, even in the unavailability of the primary control.  
           [0006]    In order to meet this object, the present invention provides a valve system for regulating a heat transferring system which comprises a valve member in combination with both an electrical actuating member and a secondary actuating member that operates thermostatically to drive the valve. This secondary actuating member is generally exposed to the regulated medium and is designed to react at a predetermined temperature of the regulated medium. When the temperature of the regulated medium is above a predetermined level, the secondary actuating member drives the valve into a position such that overheating of the system is prevented.  
           [0007]    Because the drive function of the secondary actuating member is controlled thermostatically and independently of the primary actuating member, the present invention provides a safety function that is completely independent of—and immune to the failure of—the primary, controlled drive. Damage to the system is prevented by predetermining a temperature, somewhat below the maximum tolerable operating temperature, above which the thermostatic actuating member will operate to force the cooling of the system, preventing the system from exceeding the maximum tolerable operating temperature.  
           [0008]    In one embodiment, the valve member is a rotary slide valve, which rotates about a shaft. The thermostatic actuating member is positioned within the flow of the regulated medium (and thus is sensitive to the temperature of that medium) and further positioned to drive an arm attached to the shaft of the rotary slide valve. During normal operation, the electrical actuating member drives the rotary slide valve independently of the thermostatic operating element. However, if the predetermined temperature should be exceeded, such an exceptional condition indicates a possible failure of the electric drive itself, loss of control over the electric drive, or some other failure which necessitates override of the electrical drive. In the event of such an override condition, the thermostatic actuating member drives the arm of the shaft and forces the rotary slide valve into a fully open position. The rotary slide valve can only be retracted from this position when the reaction temperature has again fallen below the predetermined level.  
           [0009]    In another embodiment of the invention, the thermostatic actuating member is positioned between the electrical actuating member and the valve member. During normal operation, the thermostatic actuating member is in a retracted position, but because of the arrangement of the members, transfers the force generated by the action of the electrical actuating member to the valve. If a predetermined temperature is exceeded, the thermostatic actuating member generates an additional drive movement, which drives the valve member into its open position.  
           [0010]    In still another embodiment of the present invention, the thermostatic actuating member is positioned such that, during an override condition, it drives the valve directly rather than by means of a shaft arm. Such a configuration enables the thermostatic actuating member to drive the valve independently of the operation of the electrical actuating member or of the presence of any particular elements of the electrical actuating member.  
           [0011]    In still another embodiment of the invention, the thermostatic operating element is positioned within a mixing chamber, into which fluid from multiple inlets is communicated. Typically, one inlet will communicate hot fluid (such as fluid returning from cooling an internal combustion engine) and another will communicate cooled fluid (such as from a radiator or a reservoir) into the mixing chamber. The valve member is designed to permit hot fluid, cooled fluid, or a combination of the two to flow into the mixing chamber. The thermostatic actuating member is positioned such that, during an override condition, it drives the valve so as to increase the flow of cooled fluid and decrease the flow of hot fluid into the mixing chamber.  
           [0012]    Further characteristics and advantages of the invention may be observed from the subsequent description of the embodiments represented in the drawings. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0013]    [0013]FIG. 1 is a cross-sectional view of a regulating valve with a rotary slide valve.  
         [0014]    [0014]FIG. 2 is a cross-sectional view of a regulating valve with an axial slide.  
         [0015]    [0015]FIG. 3 is a cross-sectional view of a regulating valve with a main valve disk and a bypass valve disk.  
         [0016]    [0016]FIG. 4 is a cross-sectional view of a flow-through valve with a flap.  
         [0017]    [0017]FIG. 5 is a cross-sectional view of a flow-through valve with two valve disks.  
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0018]    [0018]FIG. 1 illustrates a cross-sectional view of a valve for regulating the coolant temperature of, for example, an internal combustion engine. It comprises a valve housing  10  with a first inlet  11  for a liquid coolant coming from an engine outlet, which coolant has been heated by the engine (not shown). A second inlet  12  communicates coolant from a coolant radiator (not shown). These two coolant flows are brought together in a mixing chamber  13 , which comprises an outlet for communicating the coolant flow back to the internal combustion engine. A rotary slide valve  14  is disposed to control inlets  11 ,  12 . Rotary slide valve  14  rotates about a shaft  16  and is provided with a window  15 . Through rotation about shaft  16 , window  15  can be positioned in a number of configurations. In one configuration, the connection between inlet  11  and mixing chamber  13  is open, while the connection between inlet  12  and mixing chamber  13  is closed. In another configuration, the connection between inlet  11  and mixing chamber  13  is closed, while the connection between inlet  12  and mixing chamber  13  is open. Alternatively, the window may be positioned so that both connections between inlets  11 ,  12  to mixing chamber  13  are partially open.  
         [0019]    Rotary sliding valve  14  is cup-shaped and is positioned on shaft  16 , which may be a part of or attached to electrical actuating member  17 . Electrical actuating member  17  may be a proportional magnet, a DC motor, a linear motor, a step motor, or any other means for actuating rotary sliding valve  14 . Shaft  16  is further seated within mixing chamber  13  by means of bearings  18 .  
         [0020]    Arm  19  is attached to the shaft and extends radially therefrom. Thermostatic actuating member  20  is positioned within mixing chamber  13  so that transverse motion of thermostatic actuating member  20  exerts a force on arm  19 . Thermostatic actuating member  20  constitutes an auxiliary actuating drive with an extension direction running transversely with respect to shaft  19 . Thermostatic operating element  20  comprises a housing  21 , which is fixedly mounted within mixing chamber  13 . Housing  21  is filled with an expandable material (such as a wax mixture) that expands when heated above a predetermined temperature. The predetermined temperature will be selected according to the heat tolerances of the regulated system and will lie in the upper portion of the tolerated range, above the temperature of normal operation. Work piston  22  of thermostatic actuating member  20  acts on a cup-shaped transfer element  23 , which is arranged to drive arm  19  of shaft  16 . Cup-shaped transfer element  23  extends around the housing  21  of the thermostatic operating element and is bent at right angles at its open end. The bent end retains a spring washer  25 , which supports a prestressed restoring spring  24 . The opposite end of prestressed restoring spring  24  is supported on an annular collar of housing  21 .  
         [0021]    When the predetermined reaction temperature has been reached and exceeded, work piston  22  is extended, carrying along transfer element  23 . Transfer element  23  in turn drives arm  19  to turn shaft  16  in such a way that rotary slide valve  14  is rotated, increasing fluid flow between inlet  12  and mixing chamber  13  and decreasing fluid flow between inlet  11  and mixing chamber  13 .  
         [0022]    If the electrical actuating member fails, thermostatic actuating member  20  acts as an auxiliary actuating drive and prevents the system from exceeding the maximum tolerable operating temperature. Thermostatic actuating member  20  may also be configured to serve a regulating function. As the operating temperature falls below the predetermined temperature, the expanded material within housing  21  contracts, enabling restoring spring  24  to pull work piston  22  and transfer element  23  back once the predetermined maximum temperature has fallen below the permissible value. Additionally, in order to provide this regulating function it would be necessary to provide shaft  16  with a second restoring spring.  
         [0023]    [0023]FIG. 2 illustrates an alternative embodiment of the present invention. The regulating valve as depicted in FIG. 2 may also be used for regulating the coolant of an internal combustion engine, for example. An axial slide  28  is the valve member in a two-piece valve housing  26 ,  27 .  
         [0024]    Valve housing  26 ,  27  is provided with an inlet  29  for coolant coming directly from the engine outlet (not shown), with an inlet  30  for cooled coolant coming from a radiator (not shown), and with a connector  31 , which permits coolant flow out from the valve into, for example, a coolant pump. In addition, valve housing  26 ,  27  comprises an inlet  32 , through which returns coolant that has been conducted through an auxiliary device, such as a heater or the like.  
         [0025]    Axial slide  28  regulates the connection between inlets  29 ,  30  to mixing chamber  33 , from which the coolant flows. Before the internal combustion engine has reached its operating temperature, coolant flowing through inlet  29  flows into mixing chamber  33 , while coolant flowing through inlet  30  is blocked. If a heater or the like has been turned on, the coolant coming from it also flows through inlet  32  directly to mixing chamber  33 , because the axial slide  28  has an open bottom. If the axial slide  28  is displaced axially (downward) out of the illustrated position, the connection between the inlet  30  and the mixing chamber  33  is opened, while the connection between the inlet  29  and the mixing chamber  33  is correspondingly decreased and, if required, completely closed. The displacement of the axial slide  28  is performed by means of electrical actuating member  34 , which may be a proportional magnet, a DC motor, a linear motor, a step motor, or any other means for actuating axial slide  28 . A thermostatic actuating member  35  is positioned as part of the drive connection between electrical actuating member  34  and axial slide  28 . Thermostatic actuating member  35  comprises housing  36 , which is located inside mixing chamber  33 . An expandable material (again, for example, a wax mixture), fills housing  36 . If a predetermined temperature is exceeded, a work piston  37  is extended out of housing  36 . Work piston  37  is supported on transfer element  38 , which is connected with actuating spindle  39  of electrical actuating member  34 . The bottom of the axial slide  28  rests against a side of an annular collar of housing  36 . Transfer element  38  extends around housing  36  and has an edge, bent at right angles, on its open end. A spring washer  40  is retained on this edge, on which a prestressed restoring spring  41  is supported. The opposite end of restoring spring  41  is supported on the annular collar of the housing  36 .  
         [0026]    If the temperature in mixing chamber  33  exceeds the preset temperature, for example because electrical actuating member  34  does not operate or respond, work piston  37  is extended out of the housing  36 . Because of this, the housing  36  is moved in relation to the work piston against the restoring spring  41 . Housing  36  drives axial slide  28  so that the connection between inlet  30  (communicating cooled fluid) and mixing chamber  33  is opened. As in the previous embodiment, thermostatic actuating member  35  can regulate coolant flow through the system by retracting when coolant temperature again falls below the predetermined temperature.  
         [0027]    Referring now to FIG. 3, still another embodiment of a regulating valve, suitable for use in a coolant circuit in an internal combustion engine, is represented in cross-section. Valve housing  42  is provided with a first inlet  43  for coolant flowing directly from the internal combustion engine, a second inlet  44  for coolant flowing from a coolant radiator, and a connector  45  leading back to the internal combustion engine. Mixing chamber  46  is located between the two inlets  43 ,  44 . The connection of mixing chamber  46  with inlets  43 ,  44  is regulated by a main valve disk  47  and a bypass valve disk  48 .  
         [0028]    The position of valve disks  47 ,  48  is fixed by means of an electrical actuating member  49 , which can be a proportional magnet, a DC motor, a linear motor, a step motor, or any other means for actuating valve disks  47 ,  48 . Drive element  50  is linearly displaceable and is connected with valve disks  47 ,  48 . A thermostatic operating element  51  is interposed between valve disks  47 ,  48 . Housing  80  of the thermostatic actuating member  51 , to which a bolt  81  receiving bypass valve disk  48  has been welded, contains an expandable material (such as a wax mixture) that expands when heated above a predetermined temperature. The predetermined temperature will be selected according to the heat tolerances of the regulated system and will lie in the upper portion of the tolerated range, above the temperature of normal operation. Under normal operation the position of the valve disks  47 ,  48  is determined solely by electrical actuating member  49 . However, if the predetermined temperature of the thermostatic actuating member  51  is exceeded (thus inducing a condition of exception operation), work piston  52  of the thermostatic actuating member  51 , which is supported on the drive element  50  of the electrical actuating member  49 , is extended. Housing  80  of thermostatic actuating member  51 , together with valve disks  47 ,  48 , are displaced in the opening direction, so that an increased amount of cooled coolant is communicated into mixing chamber  46  through inlet  44 .  
         [0029]    Drive element  50  of electrical actuating member  49  is provided with an annular collar, on which a prestressed restoring spring  53  is supported. The opposite end of the prestressed restoring spring  53  is fixedly connected via a retaining element  54  with the housing of the thermostatic operating element  51 .  
         [0030]    Referring now to FIG. 4, a tube-shaped valve housing  56  is illustrated in cross-section. Flap  58  operates as the valve member in this embodiment of the present invention, and can be turned around a rotating shaft  59  by means of an electrical actuating member  60  (represented by broken lines), which can be a proportional magnet, a DC motor, a linear motor, a step motor, or any other means for actuating rotating shaft  59 . Electrical actuating member  60  is mounted coaxially with the axis of rotation of flap  58  and operates to rotate flap  58  between an open and a closed position. Thermostatic actuating member  61 , whose working direction extends parallel with the direction of flow, is positioned within the valve housing on the inlet side of the flap  58 . Housing  62  is filled with an expandable material (such as a wax mixture) that expands when heated above a predetermined temperature. The predetermined temperature will be selected according to the heat tolerances of the regulated system and will lie in the upper portion of the tolerated range, above the temperature of normal operation. When the predetermined temperature is exceeded, work piston  63  is extended out of housing  62  to drive flap  58 . Work piston  63  is positioned such that the location of the interface between work piston  63  and flap  58  is at some distance from rotating shaft  59 . When work piston  63  is extended, it exerts a torque, which opens flap  58 . Restoring spring  62  is attached to an annular collar disposed on work piston  63 , and the other end of restoring spring  62  is supported on retaining element  65 , which encloses the work piston  63  and is fixedly attached to housing  62 . Retaining element  65  holds thermostatic actuating member  61  in valve housing  56  on holder  66 , which is fastened by means of radial links to the inner walls of valve housing  56 .  
         [0031]    Referring now to FIG. 5, valve housing  67  is provided with inlet  68  and outlet  69 . Between inlet  68  and outlet  69  is positioned a valve member comprising two valve disks  70 ,  71 , which can be simultaneously displaced transversely with respect to valve housing  67  by means of an electrical actuating member  72 . As in all the other embodiments, electrical actuating member  72  can be a proportional magnet, a DC motor, a linear motor, a step motor, or any other means of driving valve disks  70 ,  71 . A thermostatic actuating member  74  is positioned between drive element  73  and the valve disks  70 ,  71 . Housing  75  of thermostatic actuating member  74  holds valve disk  71  by means of an annular collar. Valve disk  70  is mounted on bolt  79 , which is in turn mounted to the end of housing  75  opposite drive element  73 . Work piston  76  is located in the extension of drive element  73  of the actuating drive. Restoring spring  77  is attached at one end to work piston  76  and at the other to retaining element  78 , onto which housing  75  has been fastened.  
         [0032]    Housing  75  is filled with an expandable material (such as a wax mixture) that expands when heated above a predetermined temperature. The predetermined temperature will be selected according to the heat tolerances of the regulated system and will lie in the upper portion of the tolerated range, above the temperature of normal operation. When the predetermined temperature is exceeded, work piston  76  exerts a force on the extension of drive element  73 , therefore driving housing  75  and valve disks  70 ,  71  into a position that is more open than that dictated solely by drive element  73 .  
         [0033]    It will therefore be readily understood by those persons skilled in the art that the present invention is susceptible of broad utility and application. Many embodiments and adaptations of the present invention other than those herein described, as well as many variations, modifications and equivalent arrangements, will be apparent from or reasonably suggested by the present invention and the foregoing description thereof, without departing from the substance or scope of the present invention. Accordingly, while the present invention has been described herein in detail in relation to its preferred embodiment, it is to be understood that this disclosure is only illustrative and exemplary of the present invention and is made merely for purposes of providing a full and enabling disclosure of the invention. The foregoing disclosure is not intended or to be construed to limit the present invention or otherwise to exclude any such other embodiments, adaptations, variations, modifications and equivalent arrangements, the present invention being limited only by the claims appended hereto and the equivalents thereof.