Abstract:
A three-way heating system valve having a bypass valve between a heat source supply port and heat exchanger supply and heat source return ports for proportioning flow through the heat exchanger supply and heat source return ports, and including a differential pressure determining device between the heat exchanger supply and return ports. The pressure determining device may be a pressure relief valve and/or a pressure indicator.

Description:
BACKGROUND OF THE INVENTION  
         [0001]    The present invention relates generally to three-way valves, and more particularly to three-way heating system valve apparatus incorporating heat exchanger pressure differential determining structure.  
           [0002]    Three-way valves of the type having a by-pass valve for proportioning flow between first and second outlet ports are frequently employed as mixing or distributing valves in heating, cooling and air conditioning installations. In such installations, a three-way valve is arranged between a pipe supplying a heating or cooling liquid from a boiler or cooling apparatus and a heat exchanger adapted to heat and/or cool an air conditioned space. In systems employing a plurality of heat exchangers connected in parallel to a common supply pipe, it is usual to employ regulator valves for maintaining pressure balance between the heat exchangers.  
           [0003]    German patent document DE 195 40 580 A1 discloses a valve structure incorporating an integral regulating valve for facilitating pressure balance. The pressure differential at the output of the valve structure may then be measured, and the regulating valve set to control the heat energy provided to the heat exchanger. In order to measure the pressure differential, control plugs are provided at the output side of the valve structure to permit connection of a pressure gauge.  
           [0004]    It obviously would be desirable to minimize the complexity of the previously described pressure differential determining arrangement. The present invention provides for integrating pressure differential measurement and outlet pressure regulation features into a three-way valve structure.  
         BRIEF SUMMARY OF THE INVENTION  
         [0005]    The invention is a three-way valve including a bypass valve for portioning fluid entering a heat source supply port between a heat source return port and a heat exchanger connected between heat exchanger supply and return ports, the three-way valve further including a pressure determining device for determining the pressure differential between the heat exchanger supply and return ports. The pressure determining device may be a pressure regulator or a differential pressure indicator. The pressure regulator may be of a design which provides a fixed pressure difference, or may be adjustable. Finally, the pressure determining device may be formed in a passageway in the valve structure between the heat exchanger supply and return ports.  
           [0006]    Accordingly, the invention provides for an improved three-way valve into which differential pressure regulation and/or indication are integrated to achieve simplified construction and installation. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0007]    [0007]FIG. 1 is a sectional view of a three-way valve of prior art design;  
         [0008]    [0008]FIG. 2 is a sectional view the prior art valve of FIG. 1 taken along lines  2 - 2 , showing details of pressure control apparatus incorporated into the valve structure;  
         [0009]    [0009]FIG. 3 is a sectional view of a first embodiment of a three-way valve according to the present invention;  
         [0010]    [0010]FIG. 4 is a sectional view of a second embodiment of a three-way valve according to the present invention; and  
         [0011]    [0011]FIG. 5 is a sectional view of a third embodiment of a three-way valve according to the present invention. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0012]    In FIG. 1, reference numeral  10  identifies a three-way mixing valve of prior art design including a housing  12  of “H” shaped configuration. Housing  12  defines an inlet port  13 , first and second outlet ports  14  and  15 , and a return port  16 . Inlet port  13  is connected to first outlet port  14  by means of a passageway containing a first valve seat  17 , and to second outlet port  15  through a passageway containing a second valve seat  18 . Valve seats  17  and  18  cooperate with a closure body  20  whose position relative to the valve seats is determined by an actuator  21  connected to closure body  20  through a valve stem  22 . Valve seats  17  and  18  are concentric with and spaced along an axis  24  with which closure body  20  and valve stem  22  are aligned. Actuator  21  is shown as a knob which is rotatable about axis  24 , and which cooperates with housing  12  such that when rotated relative to the housing, it causes closure body  20  to be differentially positioned between valve seats  17  and  18  to cause fluid entering inlet port  13  to be differentially proportioned between outlet ports  14  and  15 .  
         [0013]    As shown in FIG. 1, mixing valve  10  is connected in a heating system wherein a fluid (typically water) is pumped from a heat source  26 , such as a boiler, into inlet port  13  by means of a pump  27 , and water leaving outlet port  14  is returned to heat source  26 . A heat exchanger  30  associated with a space in which the air is to be temperature controlled is connected between outlet port  15  and return port  16 . In the following description, ports  13  and  14  are sometimes referred to as heat source supply and return ports, respectively, and ports  15  and  16  are sometimes referred to as heat exchanger supply and return ports, respectively.  
         [0014]    As shown in FIG. 1, housing  12  includes an extension  32  along axis  24  into which is fitted a regulating insert  33 , which is rotatable about axis  24 , and is configured to provide variable closure of the passageway leading to outlet port  14 , thereby controlling the pressure in heat exchanger  30 . In particular, regulating insert  33  includes a circular plug on which is formed a knob  34  for facilitating rotation of the plug. Also formed on the plug, as can best be seen in FIG. 2, is a shutter portion  35  offset from axis  24  and configured to cover a variable portion of the passageway leading to outlet port  14 , depending on the rotational position of insert  33  relative to housing  12 .  
         [0015]    Regulating insert  33  is shown secured in housing  12  by means of a snap ring  36  which cooperates with corresponding grooves in the housing and regulating insert. An O-ring  37  provides a seal between housing  12  and regulating insert  33 . Regulating insert  33  provides for adjusting the flow through heat exchanger  30  in order to control the heat energy delivered by the heat exchanger.  
         [0016]    Except as will be described hereinafter, the embodiments of the present invention shown in FIGS.  3 - 5  are identical to the prior art embodiment of FIGS. 1 and 2. Identical elements in all Figures are identified by the same reference numerals.  
         [0017]    As shown in FIG. 3, housing  12  also defines a passageway  50  parallel with, but offset from axis  24 , passageway  50  extending between the passageways leading to outlet port  15  and return port  16 . Within passageway  50  is a differential pressure relief valve  52  comprising a valve seat  54  formed in housing  12 , against which a spring  56  biases a closure body  58 , the spring being compressed between the closure body and a fixed spring seat  60 . As in the system of FIG. 1, flow through heat exchanger  30  may be adjusted by regulating insert  33 , thereby controlling the heat energy provided by the heat exchanger.  
         [0018]    Pressure relief valve  52  provides for a fixed pressure differential across heat exchanger  30 , and serves to assure that the pressure differential determined by spring  56  is produced across heat exchanger  30  between outlet port  15  and return port  16 . The heat energy supplied to heat exchanger  30  can then be set by actuator knob  21 , and will remain substantially stable for any particular setting thereof.  
         [0019]    A second embodiment of the invention shown in FIG. 4 also incorporates integral passageway  50  in parallel with the passageway containing valve seat  17  between inlet port  13  and outlet port  14 . The portion of housing  12  defining passageway  50  includes a tubular extension  62  which protrudes into a passageway between outlet port  14  and return port  16 , and which terminates in a valve seat  64  of a differential pressure relief valve  65  of the type disclosed in German utility model 92 11 659.  
         [0020]    Valve  65  is shown having a closure disk  66  which is biased against valve seat  64  by a spring  67 . Spring  67  is arranged to be variably compressed between closure disk  66  and an adjustable spring seat  68  whose position can be varied by a knob  69  which controls the axial position of the spring seat to provide for an adjustable pressure differential across heat exchanger  30 . The particular design shown for this arrangement includes a bonnet  71  having an external thread which cooperates with an internal thread of an external tubular extension  72  of housing  12  aligned with extension  62 .  
         [0021]    The third embodiment of the invention shown in FIG. 5 incorporates a differential pressure indicating device  75  of a design also disclosed in German utility model 92 11 659. Pressure indicating device  75  is in the form of a transparent tubular assembly which provides a the passageway parallel to the passageway containing valve seat  17  between inlet port  13  and outlet port  14 . The transparent tubular assembly, which forms a sight glass, is made up of an outer glass tube  76  and an inner plastic tube  77 . As shown, the transparent tubular assembly at its opposite ends, is sealed to the portions of housing  12  defining outlet port  15  and return port  16  by means of O-rings, and is retained in the housing by means of an insert  78  having an external thread which cooperates with an internal thread in a boss  79  formed in the housing. A piston  80  within the transparent tubular assembly is biased upwardly by means of a spring  81  compressed between the piston and a fixed spring seat  82  mounted in a receiving cup  83  formed in the portion of housing  12  that defines return port  16 .  
         [0022]    Obviously it would be possible to combine the differential pressure relief valve shown in FIG. 4 and the differential pressure indicating device shown in FIG. 5 in a single integrated structured, which combination is known from German utility patent 92 11 659. European patent 0 455 678 discloses an alternative form of a differential pressure indicating device which may be substituted for the indicating device shown in FIG. 5, and which may also be integrated into a valve structure with the differential pressure relief valve shown in FIG. 4.  
         [0023]    Finally, although not shown in FIGS. 4 and 5, a regulating insert such as insert  33  may also be incorporated into these improved three-way valve embodiments.