Patent Abstract:
An insert snaps into position in a manifold of a fluid device to perform a baffling function. The insert includes a cradle having a base portion and opposed spring fingers for retaining the insert in position. The base portion can be completely closed to prevent flow through the insert, or have a spring flapper valve or bimetallic flapper valve to permit partial or full flow through the insert under predetermined conditions.

Full Description:
FIELD OF THE INVENTION 
   This invention relates to flow-circuiting in fluid devices such as heat exchangers. 
   BACKGROUND OF THE INVENTION 
   Heat exchangers are commonly used to remove heat from fluids. In the context of the automotive field, for example, it is well-known to use heat exchangers as oil coolers, to transfer heat from engine oil or transmission fluid to engine coolant. 
   One known type of oil cooler is constructed from a stack of thin-gauge metal plates. The plates are formed such that, in the stack, interstices are formed, the plates and interstices being disposed in alternating relation. The interstices define a plurality of oil passages and a plurality of coolant passages. The oil passages and the coolant passages are disposed in the stack in alternating relation. Thus, each plate separates a respective oil passage from a respective coolant passage, thereby to conduct heat between any contents of the oil passage and any contents of the coolant passage when a temperature differential exists therebetween. The oil passages are coupled to one another in parallel to provide an oil flow path, and the coolant passages are coupled to one another in parallel to provide a coolant flow path. Thus, when a flow of relatively hot oil is delivered to the oil flow path and a flow of relatively cold coolant is delivered to the coolant flow path, a flow of relatively cool oil and a flow of relatively warm coolant results. 
   As is well known, the heat transfer efficiencies of such structures is a function of the temperature differential between the fluid inlet and outlet, and the relative direction of flow of the fluids passing through the structures. 
   Normally, it is necessary to manufacture a variety of heat exchangers of varied dimensions to provide heat transfer performance suitable or a particular application in which it is to be employed. However, this necessitates relatively short production runs, which has an associated cost. As well, flexibility for a given application demands that a variety of heat exchangers be on hand, which has an associated inventory cost. Modern manufacturing is very cost-sensitive, and as such, these costs are disadvantageous. 
   In U.S. Patent Application Publication No. US 2002/0129926 A1, (Yamaguchi), published Sep. 19, 2002, it is taught to divide the plurality of oil passages into three groups; connect the oil passages of each group in parallel to form a respective oil flow subpath; and connect the oil flow subpaths in series. This provides a heat exchanger wherein the oil path is three times the length and one third the width than that of a heat exchanger of otherwise identical structure wherein all of the oil passages are connected in parallel, and which therefore has heat exchange characteristics differing therefrom. In this reference, which employs a plurality of plates including apertures for forming manifolds for oil and coolant, such separation is attained by omitting the openings in selected plates. This structure arguably overcomes in part the problem of short production runs, since a variety of heat exchangers can be provided simply by altering the number and position of the plates in which openings are omitted. However, this structure does not overcome the problem of inventory cost associated with flexibility. 
   SUMMARY OF THE INVENTION 
   In the present invention, an insert is provided. The insert can be snap-fit into place anywhere desired in a fluid device manifold to perform a flow baffling function. This permits a variety of heat exchangers of varying performance characteristics to be readily constructed from a single inventory of basic heat exchange elements, thereby reducing the costs of flexibility and inventory associated with devices of the prior art. 
   According to one aspect of the invention there is provided an insert for use with a fluid device having a flow distribution passage defined by a peripheral wall formed with opposed recesses therein. The insert comprises a cradle dimensioned to be slidably located in the flow distribution passage to block flow through the flow distribution passage. The cradle has opposed, resilient, outwardly disposed fingers adapted to engage the opposed recesses and retain the insert at an operative position in the flow distribution passage to perform a flow baffling function in use. 
   According to another aspect of the invention, there is provided a heat exchanger for use with a heat exchange fluid. The heat exchanger comprises a heat exchange element including: a pair of manifolds; and a plurality of heat exchange flow passages extending between the manifolds for the passage of heat exchange fluid through the heat exchange element. One of the manifolds has a flow distribution passage defined by a peripheral wall formed with opposed recesses therein. An insert includes a cradle that is dimensioned to be slidably located in the flow distribution passage in an operative position to block flow through the flow distribution passage. The cradle has opposed, resilient, outwardly disposed fingers engaged in the opposed recesses to retain the insert in the operative position. 
   Advantages, features and characteristics of the present invention, as well as methods of operation and functions of the related elements of the structure, and the combination of parts and economies of manufacture, will become apparent upon consideration of the following detailed description With reference to the accompanying drawings. A brief description of the drawings follows. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a perspective view of a heat exchanger according to a first preferred embodiment of the present invention; 
       FIG. 2  is a side, partially cut-away view of the heat exchanger of  FIG. 1 ; 
       FIG. 3  is a perspective view of an insert according to a second preferred embodiment of the present invention, the insert being a component of the heat exchanger of  FIG. 1 ; 
       FIG. 4  is a view, similar to  FIG. 2 , of a heat exchanger according to a third preferred embodiment of the present invention; 
       FIG. 5  is a view, similar to a portion of  FIG. 2 , of a heat exchanger according to a fourth preferred embodiment of the present invention; 
       FIG. 6  is a perspective view, similar to  FIG. 3 , of an insert according to a fifth preferred embodiment of the present invention; 
       FIG. 7  is an exploded perspective view of the insert of  FIG. 6 ; and 
       FIG. 8  is a view, similar to  FIG. 2 , of a heat exchanger according to a sixth preferred embodiment of the present invention. 
   

   DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     FIG. 1  shows a heat exchanger  20  according to a first preferred embodiment of the present invention. 
     FIG. 2  is a side, partially cut-away view of the heat exchanger  20  of  FIG. 1 . From  FIG. 2 , it can be seen that the heat exchanger  20  comprises a fluid device in the form of a heat exchange element  22 . The heat exchanger  20  also comprises an insert  24 . 
   The heat exchange element  22  is for use as part of a coolant circuit (not shown) and as part of an oil circuit (not shown) and is of the donut type. That is, it includes a central aperture  26  (delineated in phantom outline in  FIG. 2 ), to permit mounting on a threaded pipe attached to an engine block (neither shown). This permits the subsequent threaded engagement of an oil filter (also not shown) onto the pipe, to hold the heat exchange element  22  in place against the engine block. It should be understood that other configurations are possible. For example, the heat exchange element need not be of the donut type. As well, the heat exchange element could be an air-cooled radiator, in which event a liquid coolant circuit would not be involved therewith in use. Further, the heat exchange element could be used for cooling or heating fluids other than oil. Additionally, the heat exchange element could be for use as part of multiple heating or cooling circuits and/or multiple oil circuits. 
   Preferably, the heat exchange element  22  is of the stacked-plate type, comprising a plurality of plates  28  of aluminum, brazed to one another. The plates are arranged back-to-back into plate pairs. The plates  28  have apertures  30  formed therein. The apertures  30  are ringed or encircled by raised bosses  32 , and when the plates  28  are stacked against one another into the plate pairs, the bosses are opposite facing with the apertures  30  and the bosses  32  aligned. The bosses  32  thus form a pair of spaced-apart manifolds  34 , 34 ′ which each define a respective flow distribution passage  36 , 36 ′. 
   Each manifold  34 , 34 ′ has a respective central, longitudinal axis A-A. The peripheral edges of apertures  30  in abutting bosses  32  define a plurality of axially spaced-apart annular ridges  38  projecting into the flow distribution passages  36 , 36 ′. The annular ridges  38 , in turn, define therebetween a plurality of axially or longitudinally spaced-apart annular recesses or channels  40 , which also form parts of the flow distribution passages  36 , 36 ′. The bosses  32  form peripheral walls of the manifolds  34 , 34 ′. The manifolds  34 , 34 ′ are coupled to one another in heat exchanging relation such that, in use, upon a flow of heated oil being forced into one of the manifolds  34 , 34 ′, a flow of cooled oil issues from the other of the manifolds  34 , 34 ′. Such coupling is effected in this embodiment by a plurality of heat exchange fluid flow passages or oil passages, shown in phantom in  FIG. 2  and identified with reference numerals  42 , formed by the plate pairs. For greater clarity, it should be understood that in this preferred embodiment, the heat exchange flow passages  42  extend between the manifolds  34 , 34 ′ encircling the central aperture  26  in a split flow configuration. Again, other configurations are possible. 
   With continuing reference to  FIG. 2 , the donut cooler  20  also comprises a top plate  44  and a bottom plate  46 . The top plate  44  has ports  48 , 50  formed therethrough communicating with respective upper ends of manifolds  34 , 34 ′, and includes a flat surface  52  for sealingly receiving the base of an oil filter. The bottom plate  46  has a single port  54  therethrough which communicates with the bottom end of manifold  34 ′. 
   It should be understood that the heat exchange element  22  is of generally conventional construction, and therefore, only those parts necessary for an understanding of the present invention are shown in the figures and/or described hereinbefore. 
   Turning now to  FIG. 3 , the insert  24  includes a cradle  56 . The cradle  56  comprises a base portion  58 , a peripheral wall portion  60  and spaced-apart, resilient fingers  62 . The peripheral wall portion  60  is dimensioned for disposition in sliding but snug-fitting relation within a respective annular ridge  38  in  FIG. 2 . The base portion  58  spans the peripheral wall portion  60 , to check or block flow therethrough. The fingers  62  are four in number, although greater or lesser numbers can be employed, and extend outwardly from the peripheral wall portion  60  in opposed relation to one another. Each finger  62  has a V-shaped tab portion  64 , the tab portion  64  having an apex that extends outwardly. Fingers  62  are resiliently deformable from an outwardly disposed arrangement as seen in  FIGS. 2 and 3 , to an inwardly deformable arrangement. In the inwardly deformable arrangement, the fingers  62  are compressed toward one another, such that the width of the insert  24  is smaller in dimension than the ports  48 , 50 , 54  and the apertures  30 , so that insert  24  can pass therethrough. In the non-compressed or outwardly disposed arrangement, the fingers  62  extend outwardly, as shown in  FIG. 3 , such that the width of the insert  24  is larger in dimension than the ports  48 , 50 , 54  and the plate apertures  30 , as described next below. 
   The foregoing structure permits the ready construction of heat exchangers having any desired number of passes from a common heat exchange element, merely by suitably positioning inserts  24  into the manifolds thereof. Such positioning of the inserts is conveniently effected by passing the inserts through a desired port  48 , 50 , 54  using a suitable tool (not shown), and then pushing the insert through the respective manifold to a desired depth. In this process, the fingers  62  are forced inwardly into their inwardly deformed arrangement as each port  48 , 50 , 54  or annular ridge  38  is passed by the V-shaped tab portions  64 , and the fingers  62  spring or snap outwardly to their non-compressed or outwardly disposed arrangement with the V-shaped tabs  64  engaging opposed recesses  40  in the manifolds, to retain the insert in the location desired. 
   The heat exchanger of  FIG. 2  is an example of a single pass heat exchanger constructed in this manner. As is evident, in this embodiment, a single insert  24  is provided. The peripheral wall portion  60  of such insert  24  is disposed in snug-fitting relation within an upper annular ridge  38  of manifold  34 ′. The insert  24 , and more particularly, the base portion  58  thereof, thus stops or blocks flow from flow distribution passage  36 ′ through port  50  when disposed in this terminal location in the manifold  34 ′. As will also be seen, as so positioned, the fingers  62  releasably engage the uppermost of the annular recesses or channels  40 , to lock the insert  24  in this operative position. It will be understood that the portions of the annular recess  40  in which fingers  62  are located are considered to be opposed recesses for the purposes of this specification. Such opposing location of said recesses serves to lock the insert  24  against axial movement. Discrete opposed recesses (not shown) or sockets may be provided in the place of annular recesses  40 , if desired. For example, if the base portion  58  of insert  24  was circular, it may be advantageous to provide discrete recesses for the fingers, to resist rotation of insert  24 . 
   In use, oil from an engine block (or another heat exchange fluid) is received into manifold  34 ′ through port  54  in the bottom plate  46 . The insert  24  blocks flow through port  50 . This forces oil introduced into manifold  34 ′ to flow through oil passages  42 . Oil exiting from the oil passages  42  is collected by manifold  34  and exits through aperture  48  in the top plate and into an oil filter, for example, and subsequent return through the central aperture  26  as mentioned above. It will be evident that a device with similar functionality could be obtained by omitting bottom plate  46 , and fitting an additional insert in the lowermost position of manifold  34 . Top plate  44  could also be omitted. As well, it should also be apparent that the device could function equally well if flow was reversed, that is, if flow was received from a filter or other device into manifold  34  via port  48 . In such situation, the flow would flow through the oil passages  42 , be collected in manifold  34 ′, and then exit the heat exchanger through port  54 . 
     FIG. 4  shows a two-pass heat exchanger  20 ′. In this heat exchanger  20 ′, the heat exchange element  22  is identical to that provided in  FIG. 2 , but includes two inserts  24 , disposed respectively at the upper end of manifold  34 , and at an intermediate location in manifold  34 ′. The former insert  24  blocks flow through port  48 . The latter insert  24  separates the plurality of oil passages  42  into two oil flow subpaths, A and B, as indicated in  FIG. 4 , which are connected in series to one another, each subpath A, B being composed of a group of oil passages  42  connected in parallel to one another. In use, oil is received into manifold  34 ′ through port  54  and channeled by subpath “A” to manifold  34 . From manifold  34 , the oil is channeled back to manifold  34 ′ by subpath “B”, and then issues through port  50  in the top plate  44 . Of course, flow patterns can be reversed herein as well, and the top plate and/or bottom plate can be omitted as discussed above. 
     FIG. 5  shows a three-pass heat-exchanger  20 ″. In this heat exchanger  20 ″, the heat exchange element  22  is identical to that provided in  FIG. 2 , but includes three inserts  24 , disposed respectively at the upper end of manifold  34 ′, and at intermediate locations in manifolds  34  and  34 ′. The insert disposed at the upper end of manifold  34 ′ blocks flow through port  50 . The inserts  24  disposed at intermediate locations separate the plurality of oil passages  42  into three oil flow subpaths, A, B, C connected in series to one another, each subpath A,B,C being composed of a group of oil passages  42  connected in parallel to one another. In use, oil is received into manifold  34 ′ through port  54  and channeled by subpath “C” to manifold  34 . From manifold  34 , the oil is channeled back to manifold  34 ′ by subpath “B”. Finally, oil received into manifold  34 ′ from subpath “B” is channeled back to manifold  34  by subpath “A”, and ultimately issues through port  48  in top plate  44 . Again, flow patterns can be reversed herein, and the top plate and/or bottom plate can be omitted as discussed above. 
   Referring next to  FIGS. 6 and 7 , a modified insert  24 ′ according to a fourth preferred embodiment of the present invention will next be described.  FIG. 7  is an exploded view of the insert  24 ′ of  FIG. 6 . This insert  24 ′ is similar in structure to insert  24  (similar parts being identified with like reference numerals). However, in this insert  24 ′, the base portion  58  defines a fluid port  66  to allow flow therethrough. Further, this insert  24 ′ additionally includes a flapper  68 . The flapper  68  preferably is stamped from spring steel and has a mounting part  70  and a resilient hinged tongue part  72 . The mounting part  70  is secured to the cradle  56  by a standard rivet  74 . The tongue part  72  extends away from the mounting part  70  and includes a transverse corrugation  76 . Corrugation  76  is optional. The corrugation  76  helps to bias the flapper  68  to assume a fluid tight closed configuration, wherein the tongue part  72  is disposed at a closed position whereat it abuts and bears against the cradle base portion  58  to cover fluid port  66 , as shown in  FIG. 6 . The tongue part  72  is dimensioned to restrict, and more specifically, substantially arrest flow through the fluid port  66  when the flapper  68  is so disposed. However, tongue part  72  can be shaped or dimensioned to restrict or block only a portion of fluid port  66  where it is desired to have some seepage or trickle flow through insert  24 ′. The tongue part  72  is movable by flexure of the tongue part  72  from the closed position at least partially closing fluid port  66 , to an open position, whereat the tongue part  72  is spaced from the fluid port  66  to permit flow therethrough. Usually this occurs when in cold start-up conditions, where there is high fluid pressure on the underside of insert  24 ′, but it could also occur if there is a pressure spike in the oil circuit unrelated to oil temperature. The closed and open positions of the tongue part  72  respectively define closed and open configurations of the flapper  68 . Flapper  68  could also be made of bimetallic material, as described further below. 
   Inserts of this type can be deployed to great advantage. For example, an insert  24 ′ of this type could be deployed in the structure of  FIG. 2 , in place of the insert  24  shown therein, and the spring bias of the flapper  68  could be selected to substantially arrest flow through the fluid port  66  in normal operating conditions, yet allow flow through fluid port  66  when the pressure drop across insert  24 ′ exceeds a predetermined value. This would provide selective cold flow bypass of or through the heat exchanger  20 . That is, in normal operating conditions, wherein relatively warm, substantially free-flowing oil is delivered to manifold  34 ′, the spring constant of the flapper  68  would keep the tongue part  72  in its closed position against the base portion  58  to restrict, and more specifically, substantially arrest or stop flow through fluid port  66 . Thus, most of the flow arriving at manifold  34 ′ would pass in heat exchanging relation through the oil passages  42  to manifold  34  prior to passing through port  48 . In contrast, in conditions such as cold start-up in relatively cold ambient conditions, wherein the oil is relatively cold, highly viscous oil is delivered to manifold  34 ′. In these circumstances, the flow resistance through the oil passages  42  is relatively high, with the result that the viscous oil would force the tongue part  72  to its open position, above the base portion  58 , to permit flow from manifold  34 ′ through port  50 . That is, bypass flow would occur. 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. At the same time, the structure avoids starvation of mechanical components in normal transient high pressure conditions, such as cold weather start-up, and also avoids metal fatigue that can result from pressure spikes in the thin-wall plates forming the heat exchanger, since in such conditions bypass flow occurs. 
   As a further, non-limiting example, inserts  24 ′ of this type could be deployed in the structure of  FIG. 5 , in place of the inserts  24  shown therein, with the spring bias of the flappers  68  thereof selected to provide sequential bypass. That is, in normal operating conditions, flow through the heat exchanger  20 ″ would be as shown in  FIG. 5 , i.e. the oil flow would be forced sequentially through subpaths C,B,A. In slightly elevated pressure conditions, the flapper  68  of the uppermost insert in manifold  34 ′ would open, thereby to permit a portion of the flow to bypass oil subpath A, i.e. such that all of the oil would be forced only through subpaths C,B, and very little, if any, would pass through subpath A. In moderately elevated pressure conditions, the flapper  68  of the insert in manifold  34  would also open, thereby to permit a portion of the flow to bypass oil subpath B i.e. all the oil would be forced only through subpath C, and very little, if any, would pass through subpaths B, A. In highly elevated pressure conditions, the flapper  68  of the lowermost insert in manifold  34 ′ would further open, thereby to permit most, if not all, of the oil to bypass subpaths A,B,C, i.e. the oil would not be forced to flow through any high-resistance portion of the heat exchanger. This arrangement would tend to avoid pressure-related damage to the heat exchanger, while at the same time, maintaining heat transfer functionality except under conditions of very high pressure. 
   It will be appreciated that the more passes a heat exchanger has, the higher will be the heat transfer of the heat exchanger, but the pressure drop across the heat exchanger also increases with more passes. With the present invention, the heat transfer and pressure drop characteristics of the heat exchanger can be designed to suit end user needs, simply by modifying the characteristics of the inserts. 
   As yet a further alternative, the flappers  68  can take the form of a bimetallic strip or coil, adapted to move in response to temperature variations. For example, the bimetallic characteristics could be chosen to allow full bypass flow in cold start-up conditions, and gradually reduce the bypass flow as the oil heats up and becomes less viscous such as at normal operating conditions. 
     FIG. 8  shows a heat exchanger  20 ′″ similar to the heat exchanger of  FIG. 5 . However, in this heat exchanger, modified inserts  24 ″ with bimetallic strip flappers  80  are substituted for the inserts  24  disposed at intermediate positions in the manifolds  34 , 34 ′. As well, an insert  24 ′ is substituted for the insert  24  disposed at the upper end of manifold  34 ′, although this could be a bimetallic insert  24 ″ as well. The bimetallic strip flappers  80  are constructed so as to assume the open configuration at temperatures significantly below normal operating conditions, and to assume the closed configuration at temperatures at or above normal operating conditions. This heat exchanger  20 ′″ could have selective cold flow bypass characteristics, in that it could operate as a single-pass configuration in cold or below normal temperature flow conditions, as shown in  FIG. 8 , and switch automatically to a three-pass configuration (i.e. the flow pattern shown in  FIG. 5 ) in normal or abnormally hot conditions. Of course, any configuration in between could be obtained by choosing the characteristics of the bimetallic flapper appropriately. Further, by mixing the inserts  24 ′ and  24 ″, heat exchanger  20 ′″ could have both pressure responsive and temperature responsive characteristics, as desired. 
   Having described the 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. 
   For example, whereas the present disclosure is directed largely to heat exchangers, it should be understood that the invention is not so limited. Inserts according to the present invention may be deployed in association with any fluid device defining a flow distribution passage and further defining a peripheral wall with opposed recesses that the insert can engage to be retained in position. The invention could, of course, be used with any type of fluids. 
   It will also be appreciated that other combinations of normally closed inserts  24  and inserts with bypass flappers  24 ′ and inserts with bimetallic flappers  24 ″ can be used to give a variety of flow configurations, in different operating conditions, inside the fluid devices. 
   Further, whereas the heat exchange element shown has a plurality of axially-spaced channels or opposed recesses, this need not be the case; the insert can be used with a heat exchanger having only one such channel or one pair or set of opposed recesses. 
   It should also be understood that whereas the disclosure illustrates and describes heat exchangers of generally similar construction, modifications therein are also contemplated to fall within the scope of the invention. 
   For example, the heat exchangers need not be formed of stacked plates, nor is it required that all or any of the various components be brazed to one another. The plates forming the heat exchanger could, for example, be made of other material, such as plastics, or they could be secured to one another with a suitable adhesive, such as epoxy. Tubes could be used instead of plate pairs to define some or all of the flow passages. 
   Further, whereas the flapper tongue parts illustrated in the preferred embodiments are substantially planar, it will be evident that this need not be the case, and any form of protuberance could be formed to fit, in whole or in part, in the fluid port  66 . 
   As well, the construction of the flapper need not be limited to a single material. The mounting part could be made of a different material than that of the tongue part. Coatings could also be applied to assist in sealing, especially if the flapper is made of a weaker spring material. 
   If desired, the finger tab portions  64  could be lengthened a bit and holes formed in them, so the fingers could be gripped by a suitable tool (not shown). This would allow the fingers to be deformed inwardly by the tool so that the inserts  24  could be relocated or removed, as desired. 
   Finally, the insert can be located facing up, as described, or turned upside down, to suit the direction of flow through the heat exchanger or other fluid device with which it is used.

Technology Classification (CPC): 8