Heat Exchanger

Abstract

A heat exchanger apparatus for exchange of heat between two fluids which is especially adaptable for use as an oil cooler in an internal combustion engine with the apparatus comprising a stack of successive pairs of metal plates shaped and bonded together and enclosed in a casing, the stack of plates being shaped to prvide interconnected passages for a first fluid such as the oil to be cooled, surrounding passages for a second fluid such as the liquid coolant from an internal combustion engine, and means for flowing the oil and the coolant through their respective passages to and from the engine.

Parent Case Text

CROSS REFERENCE TO RELATED APPLICATION

This application is a continuation-in-part of my copending application Ser. No. 23,191, filed Mar. 27, 1970 now abandoned.

Description

SUMMARY OF THE INVENTION

One of the features of this invention is to provide a heat exchanger apparatus having the structure set out above.

In one embodiment the heat exchanger apparatus when used to cool engine lubricating oil has means thereon for mounting an oil filter with flow connections for passage of the oil through the filter and preferably prior to passage of the oil through the oil cooling portions of the heat exchanger.

In a more specific embodiment of the invention a central conduit of the heat exchanger is used to mount the exchanger on the engine block, to mount the filter on the heat exchanger when a filter is used, to mount a cover plate in place of the filter when one is not used and to contain a bypass valve that permits passage of cold oil directly back to the engine without substantial flow through the oil cooling portion of the apparatus.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a side elevational view partially broken away of an engine block having mounted thereon a heat exchanger oil cooler apparatus embodying the invention with an oil filter of the customary type in position.

FIG. 2 is a view similar to FIG. 1 but with an enclosing cap replacing the oil filter of FIG. 1.

FIG. 3 is a plan view of the heat exchanger partially broken away and omitting both the filter of FIG. 1 and the cap of FIG. 2.

FIG. 4 is an enlarged longitudinal sectional view through the heat exchanger apparatus embodying the invention.

FIG. 5 is a plan view of one of a plurality of co-operating fluid flow plates used in the heat exchanger.

FIG. 6 is an edge elevational view of the plate of FIG. 5.

FIG. 7 is an enlarged transverse sectional view taken substantially along line 7--7 of FIG. 5.

FIG. 8 is a plan view of an agitator or turbulizer fin used between each adjacent pair of plates.

FIG. 9 is an enlarged plan view of a detail portion of FIG. 8.

FIG. 10 is a sectional view taken substantially along line 10--10 of FIG. 9.

FIG. 11 is a view similar to FIG. 4 but illustrating a second embodiment of the invention.

FIG. 12 is a view similar to FIG. 5 but illustrating a plate of this second embodiment.

FIG. 13 is a sectional view taken along line 13--13 of FIG. 12.

FIG. 14 is a sectional view taken along line 14--14 of FIG. 12.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

As illustrated in the drawings the heat exchanger apparatus 10 of this invention is shown as mounted on an engine block 11 in communication with a lubricating oil passage 12 therefrom and a second oil passage 13 leading back into the block. In addition, as illustrated in FIGS. 1 and 2, the engine block contains outlet and inlet passages for flow of liquid coolant from the coolant containing portions of the block directly to and from the heat exchanger 10 as illustrated by the broken line connections 14 and 15 of FIGS. 1 and 2 as well as the liquid conduits of FIG. 3.

The apparatus although illustrated as being used to cool lubricating oil in an engine by using liquid coolant directly from the engine can also be used for exchange of heat between any two fluids. The heat exchanger of the first embodiment of FIGS. 1-10 comprises a plurality of successive pairs of metal plates 16 that are arranged in a stack having a generally cylindrical outer configuration. Each plate 16 has an outer edge 17 and an inner opening defined by an inner edge 18. Each successive pair of plates is joined at first areas 19 adjacent their inner edges 18 and at second areas 20 inwardly of the plate outer edges 17.

Each of the stacked pairs of plates is spaced apart between the first 19 and second 20 joined areas to provide a first chamber 21 in each pair of plates. Because there are successive pairs of plates arranged in the stack as shown in FIG. 4 there are of course a plurality of successive chambers 21.

Also provided are means joining adjacent plates in each of the stacked pairs of plates at third areas 22 with these third areas being located outwardly of the second areas and in the embodiment illustrated around the periphery of the assembly of plates.

The second joined areas 20 of the plates are spaced apart as illustrated at the bottom of FIG. 4 and thereby provide a succession of peripherally located second chambers 23. Fluid flow opening means 24 are located in these second areas 20 joining the series of second chambers 23 to provide a flow manifold 25.

Each successive pair of plates 16 is spaced apart inwardly of the joined third areas 22 to provide a succession of third chambers 26 that communicate at their outer ends with the second chambers 23 and that are open at their inner ends as illustrated at 27.

As will be described in more detail herein, means are provided for flowing a first fluid, in the illustrated embodiment engine lubricating oil, radially outwardly through one group of third chambers 26 by way of their open inner ends 27 and radially inwardly through a second group of these third chambers 26 to their open inner ends 27 with the flow being by way of the first manifold 25 and also means for flowing a second fluid, in this embodiment liquid coolant from the engine, through the first chambers 21.

In the preferred apparatus the means joining the pairs of plates at their first areas 19 extend completely around the inner edges of the stack of plates thereby providing an inner flow passage means 28. Means are provided for dividing this inner flow passage means into two adjacent parts with one part 29 communicating with the one group of third chambers 26 and a second part 30 communicating with a second group of these chambers 26. In the embodiment disclosed this dividing means is embodied in a fluid flow conduit or pipe 31 extending through the inner flow passage 28 with this pipe having a first series of three circularly arranged openings 32 leading directly to the one flow passage part 29 and a second series of three circularly arranged openings 33 adjacent the second flow passage part 30. The openings 32 and 33 are axially spaced from each other along the pipe 31 and are located on opposite sides of an annular boss 34 on the outside of the pipe 31 and positioned at the midpoint of the flow passage 28 to divide it into the first part 29 and the second part 30.

In the illustrated first embodiment of the heat exchanger the joined second areas 20 are of small extent and arcuately extended as shown in FIG. 5 with the resulting fluid flow openings 24 being of similar shape. As is shown in FIG. 5 there are a plurality of these second areas 20, here shown as three, arcuately spaced around each plate 16 adjacent the periphery thereof. As illustrated, the areas 20 and their contained openings are spaced about 120.degree. apart.

There are also provided means joining adjacent plates 16 of each of the stacked pairs of plates as illustrated in FIG. 4 at an enclosing fourth area 35 and with each of the joined pairs of fourth areas being spaced from the adjacent joined pair of fourth areas to provide a succession of peripherally located fourth chambers 36 that are connected by openings 37 thereby providing a second manifold 38. The areas 66 of plates 16 surrounding openings 37 are also joined together to provide a fluid tight structure.

The assembly of joined pairs of plates 16 are capped at their opposite ends by an end plate 39 adjacent the engine block 11 and an opposite end plate 40 at the opposite end. In the illustrated embodiment there are three sets of second manifolds 38 also arranged 120.degree. apart and symmetrically arranged with respect to each other to the three first manifolds 25 previously described. In order to provide for flow of a first fluid such as the illustrated engine lubricating oil through the three second manifolds 38 there are provided in the end plate 39 three openings 41 each leading directly into a manifold 38 as illustrated in FIG. 4 while the opposite end plate 40 is provided with three similar openings 42 for flow of fluid from the three second manifolds 38. Thus with this arrangement in the illustrated embodiment the flow of fluid or oil from the engine block 11 is in three parallel paths comprising the three manifolds 38.

The assembly of stacked plates 16 is enclosed in a generally cylindrical casing 43 that has an edge 44 joined to the outer edge of the first end plate 39. The opposite end 45 of the casing 43 is spaced from the end plate 40 so as to provide an annular chamber 46. The three manifolds 38 empty into this annular chamber by way of the aligned openings 42.

The liquid coolant is conducted from the coolant containing portions of the engine block 11 by way of the previously described coolant connecting lines 14 and 15. In its flow through the heat exchanger the coolant flows through the first chamber 21 and around the three first manifolds 25 as well as around the three second manifolds 38 before returning to the coolant section of the engine block 11. This flow through the spaced chambers 21 and around the total of six manifolds provides very efficient cooling of the oil that is at the same time flowing through the assembly of third chambers 26. As is obvious, each third chamber 26 that forms a portion of the oil flow passage is surrounded by the first chamber 21 which contains the liquid coolant.

In order to further increase the coolant efficiency each third chamber 26 contains an annular agitator or turbulizer fin 47 that is illustrated in detail in FIGS. 8, 9 and 10. As is shown in FIG. 8, each fin 47 is a metal plate that is generally circular with an inner circular opening 48 that substantially coincides with the inner end 27 of the third chamber 26 in which the fin 47 is located. The outer periphery of each fin 47 is provided with three symmetrically arranged recesses 49 each of which is arranged on the outside of one of the three second manifolds 38.

As is illustrated in the enlarged details of FIGS. 9 and 10 each fin 47 comprises a plate having one set of spaced projections 63 extending out of the plane 50 of the plate on one side thereof and another set of projections 51 extending from the other side of the plane 50 of the plate and with certain of the projection 63 and 51 as illustrated in FIG. 10 being joined directly as indicated at 52. In the illustrated embodiment each projection 63 and 51 of each fin 47 is of essentially frustoconical shape with the peak of each projection being positioned against an enclosing plate 16 as illustrated in FIG. 4.

As illustrated the heat exchanger of this invention for exchanging heat between two fluids is ideally designed for cooling lubricating oil from an engine by use of the liquid coolant directly from the engine. The heat exchanger is easily mounted on the engine block 11 by having one end 52 of the pipe or conduit 31 threaded directly to the block in alignment with the other passage 13 in the block. The edge 44 of the cooler will then enclose the other oil passage 12 as illustrated in FIG. 4 and at the same time retain in position a surrounding O-ring gasket 53 to prevent oil leakage between the heat exchanger and the engine block.

The opposite end 54 of the pipe 31 can also extend beyond the heat exchanger and contains attaching means, here shown as threads 54, for attaching either an oil filter 55 as shown in FIG. 1 or an enclosing dished cap 56 as illustrated in FIG. 2. This end also holds a nut 64 retainer for the heat exchanger plates 16. In either case the oil filter 55 or cap 56 holds in position a second O-ring gasket 57 as shown in each of FIGS. 1 and 2 that surrounds the exit passages 58 leading from the annular chamber 46. Whether the oil filter 55 is used or merely the enclosing cap 56 the oil will flow outwardly of the block 11 through the passage 12 and through the three sets of second manifolds 38 in parallel flow through the exchanger. From the manifolds 38 the oil flows through the openings 42 into the chamber 46 and from there through the openings 58 either through the oil filter 55 or into the cap 56.

The oil is then directed from either the filter 55 or the cap 56 into the interior of the pipe 31 for return to the engine by way of the passage 13. If the oil is cold and therefore with a relatively high viscosity it displaces a bypass valve 60 for flow directly through the pipe 31 into the return passage 13, bypassing the heat exchanger chambers 26. This bypass valve will now be described.

The interior of the pipe 31 at about the region of the annular boss 34 is provided with an annular valve seat 59 for a spring pressed circular valve 60. This valve 60 is held in position on the seat 59 by a helical compression spring 61 one end of which bears against the valve 60 and the other end of which bears against a cross pin 62 that extends across the interior of the pipe 31. Thus with this arrangement the valve 60 is located between the two sets of openings 32 and 33.

When the oil flowing inwardly (arrow 65) through the pipe 31 is cold and viscous it exerts sufficient pressure on the valve 60 to displace it against the thrust of the spring 61 and permit the oil to flow around the valve 60 and directly into the return passage 13 without flowing through the oil cooling passages. When, however, the oil has become sufficiently heated to have a reduced viscosity it cannot then overcome the pressure of the spring 61 so that the valve 60 closes. In one typical embodiment of this invention the spring 61 was designed to close at about 10 pounds per square inch pressure.

With the valve 60 closed by the spring 61 the oil thereupon flows radially outwardly through the set of three openings 32 and through the first set of oil flow chambers 26 and into the corresponding chambers 23 of the first manifold 25. These are of course the chambers 26 on the upstream side of the boss 34. Then the oil flows through the three first manifolds 26 into the remaining oil cooling chambers 26 which are on the downstream side of the boss 34. Here the oil flows radially inwardly toward the pipe 31, through the three circularly arranged openings 33 and then axially into the engine by way of the passage 13.

During the flow of the oil in the chambers 26 which is first radially outwardly and then radially inwardly the oil is cooled by the surrounding coolant in the series of first chambers 21 and this cooling is more efficiently accomplished by reason of the agitator fin 47 in each chamber 26 which causes a turbulent flow.

The heat exchanger of this invention is very efficient in exchanging heat between two flowing fluids and occupies very small space. These general characteristics make it extremely useful as an oil cooler for cooling the oil of an engine and it can be mounted directly on the block so as to permit oil and coolant directly from the engine to flow through the heat exchanger and back to the engine. Furthermore, in one embodiment as illustrated in FIG. 1 the cooler serves as a mounting for an oil filter so that a separate mounting is not required and when the filter is used it permits preferably flowing the oil through the filter to remove any solid foreign particles before the oil is conveyed through the cooling portion of the apparatus.

Because the heat exchanger receives coolant directly from the engine and not from a radiator its performance is not controlled by the usual engine thermostat which controls flow through a radiator. This flow of coolant directly from the engine provides warm coolant at the very beginning of operation of the engine so that the viscosity of the oil is immediately lowered for flow of this decongealed oil through the cooler passages rapidly and efficiently.

As can be seen from the detailed description given above of the construction of the exchanger, the device is made up entirely of assembled sheet metal parts some of which are plates held in position within an enclosing casing. The exchanger includes a conduit 31 that also serves as a means for mounting the exchanger on the engine block and for mounting an oil filter where one is used or a flow directing cap in place of the filter.

FIGS. 11-14 illustrate a second embodiment of the invention in which oil flows through the cooler apparatus 110 and then passes on to the filter as shown at 55 in the first embodiment or the return cap 56 also shown in this first embodiment and with the second embodiment in addition providing a bypass through which the oil may flow without being cooled where cooling is not required. In this second embodiment there are the same coolant connections as in the first embodiment and with these being indicated generally at 115 in FIG. 11. As indicated, the liquid coolant flows into the apparatus as indicated at 70 and from the apparatus as shown at 71.

The heat exchanger itself comprises a series of plates 116 arranged in successive pairs with each pair having outer edges 117 joined together as illustrated in FIG. 11 and inner edges 118 that are interconnected so as to comprise joined first areas 119. Each adjacent pair of plates 116 are also joined at second areas 120 inwardly of the outer edges and each of the pairs of plates are spaced apart between their first 119 and second 120 areas to provides a series of first chambers 121 as illustrated on the right side of FIG. 11. In the illustrated embodiment these first chambers 121 receive coolant that flows through the enclosing casing 143 to cool the oil flowing through the heat exchanger in the manner to be described in greater detail hereinafter.

The stacked pairs of plates are joined at third areas 117 located outwardly of the second areas 120. These second areas 120 are spaced apart in the successive pairs of plates to provide a succession of peripherally located second chambers 123. Fluid flow opening means 124 are provided in these second areas to provide a flow manifold 125 joining the second chambers 123 in series as shown at the left side of FIG. 11.

The successive pairs of plates 116 are spaced apart inwardly of the third areas 117 to provide a series of third chambers 126 each of which communicates with a corresponding second chamber 123 and these third chambers 126 are open at their inner ends or edges to fourth chambers 136 provided between the adjacent plates of adjacent pairs as shown at the right side of FIG. 11.

These fourth chambers 136 comprise means for flowing a first fluid, such as oil in the illustrated embodiment, radially outwardly through one group of third chambers 126 by way of openings 137 in the adjacent pairs of plates. At the outer extremities of these third chambers 126 which receive oil directly from the fourth chambers 136 the interconnection to the second chambers 123 of the manifold 125 provides for flowing the oil then radially inwardly through the second set or group of oil flow third chambers 126 which in FIG. 11 are above the dividing partition 73.

The heat exchanger also provides means for flowing a second fluid through the first chambers 121 which in this embodiment is liquid coolant within the enclosing casing 143. In order to provide for flow of coolant for the second fluid through the first chambers 121 each plate 116 is provided with the series of raised areas 86 as shown in FIG. 12. These raised areas which are of small extent have flat tops which are interconnected in adjacent plates of successive pairs of plates as shown in FIG. 11 so as to hold these successive plates apart in peripheral areas. Thus as shown in FIG. 14 one side of each plate 116 which here is the left side forms a boundary for the coolant containing first chambers 121 while the opposite sides form the boundary of the oil containing third chambers 126. In order to indicate these respective sides of the plate the sides are identified with the numerals 121 and 126 in FIG. 14.

The assembly of plates are arranged in a stack as shown in FIG. 11 and the stack is assembled in a plurality of sets, here shown as two, with each set being separated from the other by the transverse partition 73. This partition is provided with one opening 74 forming a part of the flow manifold 125 and with a second opening 75 which will be described in more detail hereinafter.

In the second chambers 123 and third chambers 126 there are provided agitator fins 147 similar to the fins 47 shown in detail in the first embodiment.

In order to separate the cooling flow path and the by-pass non-cooling flow path each plate 116 is provided with a continuous ridge 76 enclosing the bypass path 77 portion of the plates and the openings 85 in which is located the pipe 131. In the assembled plates the peaks of these ridges are joined as indicated at FIG. 11 and thereby enclose the bypass path 77 and separate it from the cooling oil path 72 which includes the third chambers 126 and the interconnected second chambers 123. Oil flow in this bypass path is indicated by the dotted line arrows 79 in FIG. 11.

The enclosing casing 143 through which the coolant 70 is directed has an end plate 145 on the end opposite the plate 139 and containing a plenum chamber 158 having flow openings 80 for both the oil path flow and also the bypass path flow.

Aligned with the openings 75 in the partition 73 are a series of openings 81 in the plates. Located in the space provided by these openings and in the bottom half of the heat exchanger is a bypass valve structure 82 similar to the valve 60, spring 61 and cross pin 62 of the first embodiment as illustrated in FIG. 4. This bypass valve operates in the same manner as in the first embodiment and therefore opens when the oil is cold enough not to require cooling so that the oil can flow directly through the bypass path 77 into the filter or into the return cap as illustrated in FIGS. 1 and 2.

The heat exchanger or oil cooler of the second embodiment operates as follows. Coolant such as the coolant liquid of the engine is circulated through the casing 143 and the coolant first chambers 121 as in the first embodiment. Lubricating oil when cooling is required flows through the third chambers 126 and manifold second chambers 123 as indicated by the arrows 72 of FIG. 11. While flowing through these chambers the oil passes through and around the assembled turbulizer fins 147 for agitation and better heat transfer. In the disclosed embodiment the oil flows in parallel through the cooling chambers beneath the partition 73 and then passes from the flow manifold 124 through the openings 74 in the partition to the second set of cooling chambers that are above the partition of FIG. 11. From here the oil then flows through an end opening 84 in an end plate 140 and into either the oil filter of the type illustrated in FIG. 1 or into the return cap shown at 56 in FIG. 2 if an oil filter is not used. The oil then flows back through the fitting or pipe 131 to the engine as indicated by the arrows 165.

In the event the oil is so cold that no cooling is required the high viscosity of the oil will open the valve 82 so that the oil is directed in the bypass path and without flowing through the cooler itself, all in the same manner as described in the first embodiment.

In spite of the compact size of the heat exchanger it provides flow of oil in parallel passages radially outwardly and then radially inwardly with these passages each being surrounded by coolant and with each passage preferably containing an agitator or turbulizer fin. This type of oil flow separated into the two paths arrangement permits attaining high heat transfer between the oil and the coolant with a low pressure drop through the exchanger because the total length of the parallel flow is quite short.

The heat exchanger of this invention is also adaptable to existing oil filter locations and is readily accessible for rapid replacement or repair and can be easily removed for cleaning. It has an attractive appearance and can be used as a supplement to an existing oil cooler where greater cooling capacity is required or desired.

Having described my invention as related to the embodiment shown in the accompanying drawings, it is my intention that the invention be not limited by any of the details of description, unless otherwise specified, but rather be construed broadly within its spirit and scope as set out in the appended claims.

Claims

I claim:

1. Heat exchanger apparatus for exchange of heat between two fluids, comprising: a plurality of successive pairs of plates arranged in a stack, each said plate having an outer edge and an inner opening defining an inner edge; means joining each pair of plates at first areas adjacent their inner edges and at second areas inwardly of their outer edges, each said pair of plates being spaced apart between their said first and second areas thereby providing a first chamber in each pair; means joining adjacent plates of each of said stacked pairs of plates at third areas located outwardly of said second areas, said second areas of successive pairs of plates being spaced apart thereby providing a succession of peripherally located second chambers; fluid flow opening means in said second areas joining said second chambers thereby providing a flow manifold, said successive pairs of plates being spaced apart inwardly of said third areas thereby providing a succession of third chambers communicating at their outer ends with said second chambers and open at their inner ends; means for flowing a first said fluid radially outwardly through one group of said third chambers from their said open inner ends and radially inwardly through a second group of said third chambers to said open inner ends of said second group, said flow being by way of said manifold; and means for flowing a second said fluid through said first chambers.

2. The apparatus of claim 1 wherein said second areas of said plates are of small extent, with each plate having a plurality of said second areas arcuately spaced around the plate thereby providing a plurality of arcuately spaced sets of said second chambers, the second chambers of each said set being joined by said fluid flow opening means.

3. The apparatus of claim 2 wherein there are three of said sets equally spaced around said stack of annular plates.

4. Heat exchanger apparatus for exchange of heat between two fluids, comprising: a plurality of successive pairs of annular plates arranged in a stack; means joining each pair of plates at first areas adjacent their inner edges and at second areas inwardly of their outer edges, each said pair of plates being spaced apart between their said first and second areas thereby providing a first chamber in each pair; means joining adjacent plates of each of said stacked pairs of plates at third areas located outwardly of said second areas, said second areas of successive pairs of plates being spaced apart thereby providing a succession of peripherally located second chambers; fluid flow opening means in said second areas joining said second chambers thereby providing a flow manifold, said successive pairs of plates being spaced apart inwardly of said third areas thereby providing a succession of third chambers communicating at their outer ends with said second chambers and open at their inner ends, and said second areas of said plates are of small extent, with each plate having a plurality of said second areas arcuately spaced around the plate thereby providing a plurality of arcuately spaced sets of said second chambers, the second chambers of each said set being joined by said fluid flow opening means; means for flowing a first said fluid radially outwardly through one group of said third chambers from their said open inner ends and radially inwardly through a second group of said third chambers to said open inner ends of said second group, said flow being by way of said manifold; means for flowing a second said fluid through said first chambers; means joining adjacent plates of each of said stacked pairs of plates at an enclosing fourth area of each plate, each said joined pair of fourth areas being spaced from the adjacent joined pair of fourth areas thereby providing a succession of peripherally located fourth chambers; fluid flow opening means in each said joined pair of fourth areas thereby providing a second manifold; and means for flowing said first said fluid through said second manifold prior to flow through said third chambers.

5. The apparatus of claim 4 wherein said fourth areas of said plates are of small extent, with each plate having a plurality of said fourth areas arcuately spaced around the plate thereby providing a plurality of arcuately spaced sets of said fourth chambers, the fourth chambers of each said set being joined by said fluid flow opening means.

6. The apparatus of claim 5 wherein there are three of said sets of fourth chambers symmetrically arranged with respect to each other and to said second chambers.

7. The apparatus of claim 4 wherein each said third chamber is provided with an annular agitator fin therein.

8. The apparatus of claim 7 wherein each agitator fin comprises a plate with one set of spaced projections extending from one side thereof and a second set of spaced projections extending from the other side thereof.

9. The apparatus of claim 8 wherein each said projection is essentially frustoconical with the peak of each projection being located against a said plate.

10. The apparatus of claim 4 wherein a first of said two fluids comprises lubricating oil for an engine and a second of said fluids comprises engine coolant liquid, and there are provided an enclosing casing having a first inlet for said first fluid to said second manifold and an outlet from said second manifold to said conduit, means joining said first inlet to said engine for oil flow therethrough, and means joining said outlet to said engine for flow of oil therethrough.

11. The apparatus of claim 10 wherein there are provided means dividing said inner flow passage means into two adjacent parts, one part communicating with said one group of third chambers and the second part communicating with the second group of said third chambers, and a flow conduit for said first fluid located in said inner flow passage means, said conduit having a first side opening leading to said first group, an axially spaced second side opening leading from said second group, and means on said conduit separating said groups.

12. The apparatus of claim 11 wherein there are provided a check bypass valve in said conduit between said first group and said second group openable at a preselected pressure equivalent to the viscosity of cold congealed lubricating oil to bypass said first and second groups of said third chambers.

13. The apparatus of claim 1 wherein there are provided separating means in the plates of said stack for separating said succession of third chambers from a series of fourth chambers, means connecting said fourth chambers in series to provide a bypass path exteriorly of said path comprising said second and third chambers, and bypass valve means in said bypass path for opening said path to said first fluid when said first fluid is less than a preselected temperature.

14. The apparatus of claim 13 wherein said stack of plates are arranged in sets to provide said groups of third chambers and corresponding second chambers, each said set being separated from the next by a transverse partition having openings therein interconnecting said second chambers flow manifold and interconnecting said fourth chambers of said bypass paths.

15. The apparatus of claim 13 wherein there are provided turbulizers in said second and third chambers.

16. The apparatus of claim 13 wherein said first fluid comprises an engine lubricating oil and said second fluid comprises a coolant liquid.

17. The apparatus of claim 16 wherein there is provided an oil filter communicating with the exits of said path and said bypass path to receive oil therefrom, and a tube extending through said stack of plates on which said filter is mounted, said tube being connected to the exit from said filter for flow of oil therefrom and return to said engine.

18. The apparatus of claim 1 wherein said first chambers are provided by cooperating spacers in each said pair of plates.

19. The apparatus of claim 18 wherein each said spacer comprises a raised element in its said plate.