Patent Application
20190195375
Not Applicable.
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.
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.
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.
As shown in the exploded assembly diagram of
As shown in the cross-sectional view of
Thermostatic elements 18A-18C 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
In the illustrated embodiment (
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.
