Patent Publication Number: US-2019195375-A1

Title: Cartridge assembly for a thermally responsive by-pass valve

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     Not Applicable. 
     FIELD OF THE DISCLOSURE 
     This disclosure relates to valves having a thermally responsive element for circulating a fluid through a heat exchanger and/or a by-pass circuit, as needed, depending on the temperature of the fluid. 
     BACKGROUND OF THE DISCLOSURE 
     Thermally responsive by-pass valves are often employed in vehicle coolant systems, engine lubricant systems and transmission fluid systems to by-pass heat exchangers until these fluids have heated up to normal operating temperatures. Such valves typically have a thermostatic element that is biased, such as by a spring, to position a valve member so that a first port is blocked and a second port is open while the fluid is at a temperature below the normal operating temperature to prevent the fluid from passing through the heat exchanger (i.e., allowing the fluid to by-pass the heat exchanger). As the fluid heats up (e.g., in the engine or transmission), heat from the fluid is transferred to the thermostatic element causing a thermally responsive material contained in the thermostatic element to expand and urge a piston to move outwardly from the thermostatic element and cause the valve member to move to a different position in which the first port is at least partially unblocked and the second port is partially blocked to allow fluid to be cooled as it passes through the heat exchanger. 
     Numerous designs have been developed for thermally responsive by-pass valves. However, there remains a need for an improved thermally responsive by-pass valve that facilitates servicing and installation of the valve, i.e., a valve construction that reduces the time and effort associated with installing the valve in a vehicle and replacing internal valve components. 
     SUMMARY OF THE DISCLOSURE 
     Disclosed is a thermostatic cartridge assembly for a by-pass valve that regulates flow between two fluid circuits, and a by-pass valve employing the disclosed cartridge. 
     The cartridge includes a thermostatic body or element containing a thermally responsive material and having a piston that movably extends from one end of the thermostatic element, a sleeve carried by the thermostatic element and having a side wall, and a biasing member. The thermostatic element, sleeve and biasing member are retained within a casing between a roof at a first end of the casing and a cap joined to a second end of the casing. The thermally responsive material expands with an increase in temperature as it changes states from solid to liquid. This expansion exerts pressure which is translated against a surface of the piston and overcomes a force of the biasing member urging an end of the piston against the roof of the casing. The casing defines a first fluid port at a first end of the casing and a second fluid port at a central portion of the casing. The fluid ports interact with the sleeve to restrict or permit fluid flow through the two different fluid circuits. The cartridge comprises all internal moving components of a valve assembly, and is configured to be releasably mountable within a valve housing, such as with external threads of the cap engaging internal threads of a valve housing or with a retaining ring or clip. 
     A valve in accordance with this disclosure includes a cartridge as described releasably retained within a valve housing having a fluid outlet, a first fluid inlet in fluid communication with the first port when the piston extends from the thermostatic element due to expansion of the thermally responsive material, and a second fluid inlet in fluid communication with the second port when the piston is not fully extended, such as when the fluid is at a temperature below the normal operating temperature. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is an exploded assembly diagram of a cartridge for a thermally responsive by-pass valve. 
         FIGS. 2A-2C  are cross-sectional views showing three alternative thermostatic elements that can be used in the cartridge shown in  FIG. 1 . 
         FIG. 3  is a cutaway perspective view of a thermally responsive by-pass valve using the cartridge of  FIG. 1 . 
         FIG. 4  is a cross-sectional view of the thermally responsive by-pass valve with the thermostatic element and other internal valve components positioned to block flow from a first valve inlet and allow flow of fluid from a second valve inlet. 
         FIG. 5  is a cross-sectional view of the thermally responsive by-pass valve with the thermostatic element and other internal valve components positioned to allow partial flow from the first inlet and partial flow from the second inlet. 
         FIG. 6  is a cross-sectional view of the thermally responsive by-pass valve with the thermostatic element and other internal valve components positioned to allow flow from the first valve inlet and block fluid flow from the second valve inlet. 
         FIG. 7  shows an alternate embodiment in which the cartridge is secured to the valve housing using a ring retainer and mating groove in the housing. 
         FIG. 8  is a bottom view of the embodiment shown in  FIG. 7 . 
     
    
    
     DETAILED DESCRIPTION 
     As shown in the exploded assembly diagram of  FIG. 1 , a cartridge  10  includes a casing  12  and a cap  14  having threads  13 . Cap  14  is secured to an end  15  of casing  12 . Contained within casing  12 , between a roof  16  and cap  14  are a thermostatic element  18 , a sleeve  20  carried by the thermostatic element, and a biasing member  22  (e.g., coil spring) compressed between cap  14  and sleeve  20 . A retainer or clip  24  may be used to secure sleeve  20  on element  18 . 
     As shown in the cross-sectional view of  FIG. 2A , thermostatic element  18 A includes a piston  26 A that is axially movable in response to a temperature change. Element  18 A contains a thermally responsive material  28  held in a cup  30 A. A diaphragm  31 A seals thermally responsive material  28  in cup  30 A and transmit expansion of material  28  to a plug  32 A that amplifies the expansion causing piston  26 A to move linearly (upwardly) along guide  33 A, allowing piston  26  to transmit forces to move sleeve  20  within a valve  37 . 
       FIG. 2B  shows an alternative thermostatic element  18 B having a piston  26 B that is axially movable in guide  33 B in response to a temperature change. A thermally responsive material  28  is held in a cup  30 B. A diaphragm  31 B seals expansion material  28  in cup  30 B and transmits expansion to piston  26 B to move sleeve  20  within valve  37 . 
       FIG. 2C  shows another alternative thermostatic element  18 C having a piston  26 C that is axially movable in guide  33 C in response to a temperature change. Thermally responsive material  28 , held in cup  30 C expands when heated moving piston  26 C upwardly within seal  31 C, which retains material  28  in cup  30 C. 
     Thermostatic elements  18 A- 18 C are illustrative of a variety of devices that can be used to transform heat energy into mechanical energy via movement of a piston using thermal expansion materials  28 . Expansion is typically a result of a change in state from (e.g., solid to liquid). 
     As shown in the cutaway perspective view of  FIG. 3 , cartridge  10  is configured to fit within a valve housing  36  of a by-pass valve  37 . By-pass valve  37  is a section of the engine manifold housing  36  containing cartridge  10 . Illustrated casing  12  has an overall or generally cylindrical shape with a wall portion  38  having a surface that faces radially outwardly from a central axis of the cartridge which abuts an inwardly facing surface  40  of housing  36 . Cartridge  10  also defines a first port  42  (see  FIG. 1 ), which is blocked by sleeve  20  in  FIG. 3 . Housing  36  defines a first fluid inlet  43  (such as from a heat exchanger or radiator), a second fluid inlet  44  (such as from an engine), and a fluid outlet  46  (such as to the engine). 
       FIGS. 3 and 4  show the thermostatic element  18  and carried sleeve  20  in a first position in which port  42  is blocked by sleeve  20  urged by spring  22  against roof  16  of casing  12  and against seating surface of casing  12  to limit or prevent flow of fluid into valve  37  and out of fluid outlet  46 . In an engine lubrication system or engine coolant system, the valve position shown in  FIGS. 3 and 4  can be used for by-passing a cooling heat exchanger (e.g., radiator), allowing fluid to circulate directly back to the engine until it reaches a threshold temperature that causes sufficient expansion of thermally responsive material  28  to cause thermostatic element  18  and carried sleeve  20  to be urged downwardly with sufficient force to overcome the force of spring  22 .  FIG. 5  shows element  18  and sleeve  20  in a partially open position in which port  42  is unblocked allowing fluid to flow through port  42  and into valve  37 . In the partially open position shown in  FIG. 5 , a second port  48  defined in casing  12  is partially blocked by the sidewall of sleeve  20 , limiting fluid flow directly from the engine. This provides a mixture of fluid from the cooler and fluid directly form the engine to flow from outlet  46  to the engine. As the fluid continues to heat, further expansion of the thermally responsive material  28  in thermostatic element  18  causes element  18  and carried sleeve  20  to move toward cap  14  against compression spring  22  into a position (shown in  FIG. 6 ), in which sleeve  20  blocks port  48  and fully opens port  42 , such that flow through the by-pass is restricted or limited and most or all of the fluid (e.g., engine coolant, lubricating oil, or transmission fluid) is circulated through a heat exchanger (e.g., cooler or radiator). 
     In the illustrated embodiment ( FIG. 3 ), cap  14  is threadingly secured to the body of valve housing  36 . Alternatively, cap  14  can be made to fit within housing  36  and be held in place with a snap or retaining ring  50  ( FIGS. 7 and 8 ). A mating groove  52  can be present within the housing. 
     As the circulated fluid begins to cool (such as during engine idle or after the engine is turned off), the thermally responsive material cools and contracts allowing spring  22  to urge sleeve  20  toward roof  16  to close port  42  and open port  48 . 
     Such by-pass valves including known by-pass valves, improve fuel efficiency by allowing fluids to by-pass cooling heat exchangers and heat up more quickly until the engine and fluids have reached a fuel efficient operating temperature. Such by-pass valves are also desirable to allow fluids (especially lubricants) to achieve a lower viscosity at the higher temperature, thereby reducing wear on pumps due to high back pressure through the heat exchanger when the fluid is at a low temperature. 
     The by-pass valve disclosed herein has the advantage of allowing the moving or operable components, namely the thermostatic element, ports, seating surfaces and biasing member, to be present in a cartridge assembly that can be easily installed or removed, such as for servicing or replacement of valve components. The cartridge can also be removed during brazing or welding operations on the valve housing  36  to avoid damage to the internal valve component, such as during installation. 
     It is also believed that the cartridge structure reduces the number of components required for a thermostatic by-pass valve. In particular, by having the outwardly protruding end  34  of the piston  26  engage a roof  16  of casing  12 , the need for a return spring, poppet valve and spring retainer featured in conventional thermostatic by-pass valves is eliminated. 
     Accordingly, it is to be understood that the above description is intended to be illustrative and not restrictive. Many embodiments and applications other than the examples provided would be apparent upon reading the above description. The scope of the invention should be determined with reference to the appended claims along with the full scope of equivalents to which such claims are entitled. It is anticipated and intended that future developments will occur, and that the disclosed systems and methods will be incorporated into such future embodiments. In summary, it should be understood that the invention is capable of modification and variation. 
     All terms used in the claims are intended to be given their broadest reasonable constructions and their ordinary meanings as understood by those knowledgeable in the technologies described herein unless an explicit indication to the contrary is made herein. In particular, use of the singular articles such as “a,” “the,” “said,” etc., should be read to recite one or more of the indicated elements unless a claim recites an explicit limitation to the contrary.