Patent Application
20060237079
This invention relates to valves, and in particular, to flapper valves.
Automotive fluids, such as engine oil or transmission fluids, absorb heat in use. To prevent fluid deterioration, this heat often needs to be removed. Heat exchangers are commonly used for this purpose. Moreover, heat exchangers are known to perform this function adequately in moderate ambient conditions. However, in cold ambient conditions, engine oils and transmission fluids can be highly viscous. In such conditions, automotive fluids do not flow easily through heat exchangers. As a result, in such conditions, the interposition of a heat exchanger in an oil circuit can disadvantageously impede circulation. Starvation of some downstream components, like transmissions, may even occur.
In order to avoid these adverse effects, it is known to provide a mechanism for bypassing the heat exchanger. One way that this has been done in the past is to provide a bypass conduit. The bypass conduit is connected in parallel with the heat exchanger and has a relatively low resistance to the flow of high viscosity fluids as compared to the heat exchanger. Structures of this type are known to avoid starvation of downstream components, but can suffer in that, in normal operating conditions, the flow is split between the heat exchanger and the bypass circuit. This requires that the heat exchangers be made proportionately larger and heavier to achieve the same overall heat exchange performance for the cooling system. This added size and weight, and the added costs associated therewith, are undesirable to automotive manufacturers.
To ameliorate the split-flow problem, it is known in the prior art to provide bypass valves. Sometimes, these bypass valves are pressure-activated, and are integrally constructed with or attached to the heat exchanger. A structure exemplary of the foregoing is shown in U.S. Pat. No. 5,236,043 (Armbruster), issued Aug. 17, 1993. This structure includes a flapper valve of spring steel biased in a closed position, to arrest bypass flow, and which is adapted to be urged open when the flow resistance through the normal passage of the heat exchanger is too high as in of cold-start conditions. Heat exchangers of this general type can avoid starvation of downstream lubricated components, and can be adapted such that bypass flow is substantially nil in normal operating conditions, thereby to permit compact heat exchanger construction. However, in Armbruster, connection of the flapper valve to the heat exchanger body is effected by a press-fitted stud. Such construction is difficult to accomplish and suffers from a propensity to leak.
Another type of flapper valve is shown in U.S. Pat. No. 3,998,571 (Falke), issued Dec. 21, 1976, wherein a flapper valve for the cylinder of a reciprocating compressor is shown. This flapper valve is part of a flapper sub-assembly having a flapper mounting portion riveted in place. However, the rivet construction also has a propensity for leakage, and the riveted sub-assembly requires separate handling and increases the cost and complexity of the device.
In the present invention, a rivet-type flapper valve assembly is provided where a main body part includes a pin portion of the rivet. The main body part is permanently attached to any heat exchanger or other fluid device. A flapper valve is then located on the pin portion which is easily deformed to complete the flapper valve assembly.
According to one aspect of the invention, there is provided a flapper valve assembly for controlling fluid flow from a flow chamber of a fluid device. The flapper valve assembly comprises of a main body part having a valve orifice therethrough for communication with the flow chamber. The main body part includes a transverse pin spaced from the valve orifice, the pin having an enlarged head. A flexible flapper valve has a mounting end portion defining a hole through which the pin extends, the flapper valve being retained in position by the enlarged head. The flapper valve also has a free end portion movable from a first position where the free end portion at least partially blocks flow through the valve orifice, to a second position where the free end portion unblocks the valve orifice. Bias means is also provided for urging the free end portion into the first position.
According to another aspect of the invention there is provided a heat exchanger comprising a heat exchange element having an end plate. The heat exchange element includes an inlet manifold, an outlet manifold and flow passages therebetween for the passage of one heat exchange fluid through the heat exchange element. The end plate defines at least one flow chamber in communication with at least one of the inlet manifold and the outlet manifold. A flapper valve assembly is attached to the end plate and includes a main body part having a valve orifice therethrough communicating with the flow chamber. The main body part includes a transverse pin spaced from the valve orifice, the pin having an enlarged head. A flexible flapper valve has a mounting end portion defining a hole through which the pin extends, the flapper valve being retained in position by the enlarged head. The flapper valve also has a free end portion movable from a first position where the free end portion at least partially blocks flow through the valve orifice, to a second position where the free end portion unblocks the valve orifice. Bias means is also provided for urging the free end portion into the first position.
According to yet another aspect of the invention there is provided a method of attaching a flapper valve to a fluid device having a flow chamber. The method comprises the steps of providing a main body part having a valve orifice therethrough and a transverse pin on the main body part spaced from the valve orifice. The main body part and the pin are permanently secured to the fluid device with the valve orifice in communication with the flow chamber. A resilient flapper valve is mounted on the pin. The pin extends through the flapper valve and the flapper valve at least partially closes the valve orifice. Also, the pin is deformed to secure the flapper valve onto the main body part.
In the accompanying drawings, which are for the purpose of illustration and description only, and are not intended as a definition of the limits of the invention:
The heat exchanger or donut cooler 22 is for use with a coolant circuit and lubrication or other fluid circuit and, by way of example, as indicated in
As best seen in
Where manifold 36 is the inlet manifold, oil is received into the manifold 36 through an aperture 37 (see
It should be understood that the heat exchange element 28 is of generally conventional construction, and therefore, only those parts necessary for an understanding of the present invention are shown in the figures and described herein.
Upon a flow of heated oil being forced into the inlet manifold 36 and a flow of coolant being delivered to the coolant inlet 32, a flow of cooled oil is produced at the outlet manifold 40 and a flow of heated coolant is produced at the coolant outlet 34. Again, this flow could be reversed.
The face plate 30 has a sealing surface 42 and a pair of openings 44,46. The sealing surface 42 is adapted to be engaged by the filter 24. The pair of openings 44,46 communicate with an annular channel (not shown) in the base of the oil filter 24. One of this pair of openings 44,46 is in fluid communication with the outlet manifold 40 for receiving the flow of cooled oil, as indicated by arrow 45 in
Turning now to the flapper valve assembly 20, same will be seen to comprise a main body part or flapper support structure 54, and a resilient flapper valve 52, the latter being constructed of spring steel. The flapper support structure 54 is disposed between and secured to each of the heat exchange element 28 and the face plate 30 and has a fluid port portion 58 defining a passage or valve orifice 60 for communication between the Inlet manifold 36 and the face plate opening 46. For clarity, the fluid port portion 58 should be understood to be a portion of the main support structure 54 immediately surrounding the valve orifice 60.
As seen best in
The flapper valve 52 has a mounting end portion 68 and a free end portion 70. The mounting end portion 68 has a hole 72 dimensioned to receive the rivet shaft. 82. At the operative position, the mounting end portion 68 abuts the top surface of main body part or support structure 54.
As best seen in
FIGS. 6 to 7A also illustrate that the thickness of plate 30 allows flapper valve 52 to be recessed or hidden inside opening 46, even when the flapper valve is open. This provides a clean or flat surface 42 on face plate 30 for mounting components, such as filter 24, or for attaching heat exchanger 22 to other objects, like an engine. This also protects the flapper valve during transportation and assembly of heat exchanger 22 to other components.
In normal operating conditions, wherein relatively warm, substantially free-flowing oil is delivered to the inlet manifold 36, bias provided by the spring steel flapper valve 52, or mounting end portion 68 thereof, maintains the free end portion 70 of the flapper valve 52 against the fluid port portion 58 to restrict or arrest flow through the valve orifice 60. Thus, most of the flow arriving at the inlet manifold 36 passes in heat exchanging relation through the heat exchange element 28 to the outlet manifold 40, transferring heat to the coolant in heat exchange element 28 in the process. The oil then passes through outlet or opening 44 in the face plate 30 to the oil filter 24, for filtering, and subsequent return to the oil circuit in a conventional manner.
In contrast, in conditions such as are present in the context of an engine start in relatively cold ambient conditions, wherein the oil is relatively cold and viscous, the pressure resistance between the inlet manifold 36 and outlet manifold 40 is relatively large, with the result that the viscous oil forces the free end portion 70 of the flapper valve 52 apart from the fluid port portion 58, as indicated by the sequence of
The mechanical properties of the flapper valve 52 are selected to suit the operating parameters of the heat exchange element and lubrication circuit with which it is used, as will be appreciated by persons of ordinary skill in the art.
The foregoing structure is of particular advantage, in that it obtains relatively high cooling performance in normal operating conditions, when cooling is needed, as substantially all oil passes through the heat exchange element to transfer heat to the coolant in such conditions. At the same time, the structure avoids starvation of mechanical components in normal transient high pressure conditions, such as cold weather startup, and also avoids metal fatigue that can result from pressure spikes in the thin-wall plates forming the heat exchange element, since in such conditions bypass flow occurs.
In the assembly of heat exchanger 22, the flapper support structure 54 is permanently attached to the heat exchange element or other fluid device 28 with the valve orifice 60 in communication with the flow chamber from which it is desired to control fluid flow. The rivet or pin 62 extends transversely from support structure 54. Flapper support structure 54 is permanently attached to fluid device 28, preferably by brazing, and preferably at the same time as the components of fluid device 28 are brazed together, but flapper structure 54 could be attached in other ways. Thereafter, the mounting end portion 68 of the flapper valve 52 is put into its operative position. That is, the end of the flapper valve 52 with the hole 72 therein is put on rivet 62 in abutment with the main body part 54. Thereafter, the head 64 of rivet 62 is deformed to retain flapper valve 52 in place.
Referring next to
Having described preferred embodiments of the present invention, it will be appreciated that various modifications may be made to the structures described above without departing from the spirit or scope of the invention.
Foremost, whereas the flapper valve assemblies described herein are shown in use with a heat exchanger, it should be understood that the invention is not so limited, and may be deployed in association with any fluid device having a flow chamber from which intermittent flow is desired.
Where the fluid device is a heat exchanger, different types of heat exchangers are also contemplated to fall within the scope of the invention. Heat exchangers, for example, that are not of the donut type may be utilized. As well, the heat exchangers need not be formed of stacked plates, nor is it required that the various components be brazed to one another. As well, the face plate 30 is not required; the main body part itself could be configured to mate with the oil filter or any other fluid device.
As a further modification, whereas the flapper valve of the preferred embodiment consists of a strip of simple spring steel, a resilient bimetallic strip could be readily substituted therefor. In this case, the flapper valve normally would be open in cold flow conditions, and closed under normal operating conditions. Of course, a bimetallic flapper valve would still be flexible and provide pressure spike protection even in warm flow conditions. The flapper valve could also be made of other materials, such as plastic, and it could be coated to improve its sealing properties, if desired.
As well, whereas in the preferred embodiments illustrated, the flapper valve is adapted to substantially arrest flow when the free end portion thereof is disposed at its first or closed position, this need not be the case. The free end portion could, for example, be sized to only partially cover the passage, thereby to permit a measure of bypass flow at all times.
In the embodiment shown in FIGS. 2 to 7, the rivet could be made of a resilient material having preformed heads 64 and 80 and popped or snapped into position after the support structure 54 is brazed to heat exchange element 28.
Finally, the flapper support structure or main body portion 54 could be located or orientated differently on the fluid device to which it is attached. For example, where the oil flow direction is reversed, so that it goes through filter 24 first and then through heat exchange element 28, as mentioned above, flapper valve assembly 20 would be turned upside down, so that flapper valve 52 would open inwardly into a flow passage or manifold in the device. The flapper valve 52 could also be located in an outlet passage or manifold instead of an inlet manifold.
From the foregoing, it will be evident to persons of ordinary skill in the art that the scope of the present invention is limited only by the accompanying claims, purposively construed.
