Patent Description:
<CIT> discloses a method of producing a heat exchanger, comprising: obtaining a titanium plate that has been cladded with a melting depressant foil, and heat treated for improving ductile properties; pressing a pattern in the titanium plate; stacking the titanium plate on a number of similar titanium plates; heating the stack of titanium plates to a temperature above <NUM> and below the melting point of titanium, the melting depressant foil causing surface layers of the titanium plates to melt and flow to contact points between adjacent titanium plates; and allowing the melted titanium to solidify, such that joints are obtained at the contact points between adjacent titanium plates.

<CIT> discloses a plate heat exchanger comprising a plate assembly having a plurality of heat transfer plates arranged in a stack formation wherein the plates are spaced apart from each other to define heat transfer medium passages between adjacent heat transfer plates. The plate has a plurality of contact portions. The plate heat exchanger further comprises solder disposed between and joining the contact portions of the adjacent heat transfer plates so as to integrally join the heat transfer plates thereby forming the plate assembly. Selected ones of the heat transfer medium passages allow a first heat transfer medium to flow therethrough and other heat transfer medium passages allow a second heat transfer medium to flow therethrough to thereby enable heat exchange to be effected between the first and second heat transfer media via the heat transfer plates. The solder joins the adjacent heat transfer plates which define the first heat transfer medium passage has characteristics suitable for the first heat transfer medium. The solder joining the adjacent heat transfer plates which define the second heat transfer medium passage has characteristics suitable for the second heat transfer medium.

<CIT> discloses a method of production of an inexpensive corrosion-resistant heat exchanger made of stainless steel including the steps of electroplating chrome to a thickness of <NUM> on at least one of the end faces of a plurality of first and second shaped plates made of stainless steel alternately stacked in the thickness direction so as to form a chrome-based brazing filler metal layer, then electrolessly plating or electroplating Ni-P to a thickness of <NUM> on the chrome-based brazing filler metal layer to form a nickel-based brazing filler metal layer. The first and second shaped plates are brazed together through the chrome-based brazing filler metal layer and the nickel-based brazing filler metal layer to obtain a high corrosion resistant heat exchanger. Further, a fine metal structure can be realized in the high corrosion resistance brazing filler metal filler and therefore the occurrence of cracking at the grain boundaries of the metal structure can be reduced.

<CIT> discloses a self-brazing material for use in a heat exchanger using a corrosive heat exchanger fluid is manufactured by providing a first substrate layer and a second layer metallurgically bonding the two layers together to form a composite material. This second layer is made of a material chosen from a group consisting of materials capable of having good high temperature and corrosive properties, and melting at a temperature well below that of the first material. The bonded material is then reacted so as to render the second layer a brazing layer for the first substitute layer with excellent high temperature and corrosive properties.

The invention provides a heat exchanger including a first fluid channel in thermal communication with a second fluid channel. The first fluid channel is enclosed being sealed from the second fluid channel and being sealed within the heat exchanger. In particular, the invention provides that the first fluid channel is created between two plates and is sealed by a braze joint between the two plates- the braze joint created, in part, by a copper filler material located specifically at a perimeter of the first fluid channel and contacting perimeter areas of the two plates. Locating the copper filler material specifically in this area prevents or minimizes contact between a first fluid, typically oil, within the first fluid channel and the copper material, which helps to prevent the copper material from diffusing into the first fluid and which can prevent or minimize the copper material from flowing into other parts of a mechanical system, keeping the first fluid cleaner and benefit the mechanical system. To accurately position such copper filler material, the invention further provides that the copper filler material is a foil material and, in particular, a foil braze frame. The braze frame is installed between the two plates at peripheral corners and edges of the two plates, where the two plates nest together.

The first fluid channel of the heat exchanger includes a center flow region within the perimeter of the first fluid channel and between an inlet manifold opening and an outlet manifold opening. The copper braze frame includes a frame base and a frame wall that extends from the frame base at an angle of at least <NUM> degrees from the base. The frame base includes an inner edge, and the frame wall includes an outer edge. The inner edge surrounds and defines the area of the center flow region. The inner edge extends in parallel to the outer edge along the perimeter of the first fluid channel at locations where the perimeter is adjacent to the center flow region. A width of the center flow region at the widest point of the center flow region is a separation distance between the inner edge on one side of the frame and the inner edge on another opposite side of the frame. The first fluid channel is further defined between a first plate and a second plate, which are brazed to each other at the perimeter of the first fluid channel by the braze frame. A third plate is stacked on the second plate to define a second fluid channel between the second plate and the third plate.

The heat exchanger further includes a first inlet configured to receive the first fluid, a first outlet in fluid communication with the first inlet, a second inlet configured to receive a second fluid that includes a coolant, and a second outlet in fluid communication with the second inlet. The first fluid channel provides fluid communication of the first fluid between the first inlet and the first outlet. The second fluid channel provides fluid communication of the second fluid between the second inlet and the second outlet. A turbulator or fin may be located within the first fluid channel to increase the heat transfer between the first fluid and the second fluid. The copper braze frame is located between the first plate and the second plate. Other braze filler materials like braze paste made with iron or other materials may also be used within the first fluid channel, particularly within in the center flow region. Copper or iron based braze filler materials may be used within the second fluid channel.

In another embodiment, the heat exchanger includes a braze foil sheet made with copper, and the braze foil sheet is located within the second fluid channel. The braze foil sheet includes a sheet base that extends through the second fluid channel and a sheet wall that extends from the sheet base at an angle greater that <NUM> degrees. The sheet wall extends a first height from the sheet base. In the heat exchanger, the braze foil sheet is assembled between the second plate and the third plate. When the heat exchanger is assembled, a first edge at the outer perimeter of the braze foil sheet is located between a second edge at the outer perimeter of the second plate and a third edge at the outer perimeter of the third plate. The braze foil sheet within the second channel functions as a brazing filler material for both the braze joint between the first plate and second plate and the braze joint between the second and third plate, as the braze foil sheet melts while the heat exchanger is heating in a brazing furnace, and the brazing material from the braze foil sheet migrates to the joint between the first plate and the second plate. Iron based braze filler materials may be used within the first fluid channel.

In another embodiment, the invention provides a method of manufacturing a heat exchanger, the method includes providing a first inlet configured to receive a first fluid, providing a first outlet in fluid communication with the first inlet, providing a second inlet configured to receive a second fluid that includes a coolant, providing a second outlet in fluid communication with the second inlet, providing a first plate, stacking a second plate on the first plate to define a first fluid channel between the first plate and the second plate, the first fluid channel providing fluid communication of the first fluid between the first inlet and the first outlet. The method further includes stacking a third plate on the second plate to define a second fluid channel between the second plate and the third plate, the second fluid channel providing fluid communication of the second fluid between the second inlet and the second outlet. The method further includes placing a copper foil frame between the first plate and the second plate such that the copper foil frame extends around a perimeter of the second plate and brazing the first plate to the second plate where the copper foil frame provides a filler metal that couples the first plate to the second plate. For this embodiment and method, frame walls of the copper foil frame are bent at an angle to a frame base of the copper foil frame before openings in the frame base are punched. This element of the process provides rigidity to the frame for the punching process.

According to a first aspect of the invention there is provided a heat exchanger comprising:.

The first plate may include a base and a dome that extends from the base, wherein the dome includes an aperture extending through the dome, the aperture in fluid communication with the second inlet and the aperture provides a flow path for the second fluid, and wherein the copper foil frame is located between the dome of the first plate and the second plate to provide a filler metal for brazing the dome of first plate to the second plate.

The copper foil frame may extend beyond an outer edge of the second plate and beyond an interface between the second plate and the third plate.

The heat exchanger may further comprise a turbulator in the first fluid channel and an iron braze paste between the turbulator and at least one of the first plate and the second plate for brazing the turbulator to the at least one of the first plate and the second plate.

The copper foil frame may include a frame base with an inner edge, and a frame wall with an outer edge, wherein the inner edge surrounds and defines an area of a center flow region, and wherein the inner edge extends in parallel to the outer edge at least partially around the center flow region.

The copper foil frame may include a frame base, and a frame wall, and wherein the frame wall extends away from the frame base at an angle greater than <NUM> degrees.

The copper foil frame may include a frame base, and a frame wall, and wherein a width dimension of the frame wall is greater than or equal to a width dimension of the frame base when measured along a cross-section of a side of the copper foil frame.

According to a second aspect of the invention there is provided a method of manufacturing a heat exchanger, the method comprising:.

The method may further comprise bending a perimeter of the copper foil frame, and after bending the perimeter of the copper frame, punching an opening through the copper foil frame.

The first plate may include a base and a dome that extends from the base, wherein the dome includes an aperture extending through the dome, the aperture in fluid communication with the second inlet and the aperture provides a flow path for the second fluid, and wherein placing the copper foil frame between the first plate and the second plate includes placing the copper foil frame between the dome of the first plate and the second plate to provide a filler metal for brazing the dome of first plate to the second plate.

<FIG> illustrates a heat exchanger <NUM>. In one embodiment, the heat exchanger <NUM> is a vehicle oil cooler and more particularly a layered core vehicle oil cooler. The heat exchanger <NUM> includes a base plate <NUM> and heat exchanger plates <NUM> stacked on the base plate <NUM>. In one embodiment, the plates <NUM>, <NUM> are formed from stainless steel. The base plate <NUM> can be used to mount or couple the heat exchanger <NUM> to a vehicle. The base plate <NUM> includes a first inlet <NUM> that receives a first fluid and a first outlet <NUM> in fluid communication and downstream from the first inlet <NUM>. In one embodiment, the first fluid includes oil and relatively warm oil passes into the heat exchanger <NUM> through the inlet <NUM> and relatively cool oil exits the heat exchanger <NUM> via the outlet <NUM>. The base plate <NUM> further includes a second inlet <NUM> that receives a second fluid and a second outlet <NUM> in fluid communication and downstream from the second inlet <NUM>. In one embodiment, the second fluid includes a coolant that is used to cool the oil using the heat exchanger <NUM>, as the first fluid and the second fluid are in thermal contact via thermal conduction through plate <NUM> arranged between the first fluid and the second fluid. In an alternative configuration, which is not shown, the first inlet <NUM> is arranged on an opposite long side from the first outlet <NUM>, and the second inlet <NUM> or the second outlet <NUM> is arranged on the same long side as the first inlet <NUM>. In another alternative embodiment, which is not shown, the first inlet <NUM> is on the same narrow side as the second inlet <NUM>.

Referring to <FIG> and <FIG>, the heat exchanger plates <NUM> include a first plate <NUM> and a second plate <NUM> that alternate in the sack of heat exchanger plates <NUM>. The first plate <NUM> includes a base <NUM> and a dome <NUM> that extends from the base <NUM>. The domes <NUM> each include an aperture <NUM> that extends through the dome <NUM>. The apertures <NUM> aligned with the second or coolant inlet <NUM> form a coolant inlet manifold <NUM> of the heat exchanger <NUM>. The apertures <NUM> aligned with the second or coolant outlet <NUM> form a coolant outlet manifold <NUM> of the heat exchanger <NUM>. The first plate <NUM> further includes an outer wall or edge <NUM> that extends from the base <NUM> around the perimeter of the first plate <NUM>.

The second plate <NUM> includes a base <NUM> and apertures <NUM> that extend through the base <NUM>. The apertures <NUM> aligned with the coolant inlet <NUM> form the coolant inlet manifold <NUM> of the heat exchanger <NUM>. The apertures <NUM> aligned with the coolant outlet <NUM> form the coolant outlet manifold <NUM> of the heat exchanger <NUM>. The second plate <NUM> further includes an outer wall or edge <NUM> that extends from the base <NUM> around the perimeter of the second plate <NUM>. The edge <NUM> of the second plate <NUM> is received within the edge <NUM> of the first plate <NUM> to stack or nest the plates <NUM>, <NUM>.

A first fluid channel <NUM> is formed between the first plate <NUM> and the second plate <NUM>. The first fluid channels <NUM> provide fluid communication of the first fluid (e.g., oil) between the first inlet <NUM> and the first outlet <NUM>. Referring to <FIG> and <FIG>, apertures <NUM> in the first plate <NUM> aligned with the inlet <NUM> form an oil inlet manifold <NUM>, and the aperture <NUM> aligned with the outlet <NUM> form an oil outlet manifold <NUM> of the heat exchanger <NUM>. The oil inlet manifold <NUM> distributes oil to the first fluid channels <NUM> and the oil outlet manifold <NUM> collects oil from the channels <NUM> before directing the oil to the outlet <NUM>.

In the illustrated embodiment, turbulators or fins <NUM> are located in the first fluid channels <NUM>. The turbulators <NUM> provide turbulence to the flow in the channels <NUM> to increase heat transfer between the oil and coolant. In one method of manufacturing, an iron braze paste is applied partially in particular locations to the turbulators <NUM> to braze the turbulators <NUM> to the plates <NUM>, <NUM>.

Referring to <FIG>, a third plate, which is another first plate <NUM> is stacked on the second plate <NUM> to define second or coolant fluid channels <NUM> between the plates <NUM>, <NUM>. The coolant fluid channels <NUM> provide fluid communication of the second fluid or coolant between the inlet <NUM> and the outlet <NUM>. The coolant flows through the inlet <NUM> and into the coolant inlet manifold <NUM> where the coolant is distributed to the fluid channels <NUM>. The coolant in the fluid channels <NUM> is used to cool the oil in the fluid channels <NUM> via heat transfer across the plates <NUM>, <NUM>. The coolant is received from the channels <NUM> into the coolant outlet manifold <NUM>, and the coolant exits the heat exchanger <NUM> through the coolant outlet <NUM>.

Referring to <FIG>, <FIG>, during the manufacturing process a copper foil frame <NUM> is placed between each first plate <NUM> and second plate <NUM>. The copper foil frame <NUM> melts when the heat exchanger is placed in a braze furnace, which provides a filler metal for brazing and securing the first plate <NUM> to the second plate <NUM>. The copper foil frame <NUM> extends only around a perimeter <NUM> of the plate (shown on second plate <NUM> in <FIG>). That is, the copper material of the frame <NUM> does not extend into an interior region <NUM> of the plate <NUM>. The copper foil frame <NUM> includes a only narrow strip <NUM> of copper foil that extends around the perimeter <NUM> of the plate <NUM>. Also, the narrow strip <NUM> extends around the apertures <NUM> of the plate <NUM> that form the coolant manifolds <NUM>, <NUM> such that the copper foil frame <NUM> is between the domes <NUM> of the first plate <NUM> and the base <NUM> of the second plate <NUM>. This provides a filler metal for brazing the domes <NUM> to the second plates <NUM>. The copper foil frame <NUM> is used in the first fluid or oil fluid channels <NUM> to braze the plates <NUM>, <NUM>. The construction of the frame <NUM> minimizes the amount of copper needed as filler metal to braze the plates <NUM>, <NUM> together within the oil channels <NUM>. Fluid like oil can break down copper over time and through use of the heat exchanger <NUM> and contact between the oil and copper. Therefore, it is desirable to minimize the amount of copper used in the oil fluid channels <NUM>. The copper foil frame <NUM> includes the narrow strip <NUM> of copper foil that extends only around the perimeter <NUM> of the plate <NUM>, which minimizes the use of copper in the oil channels <NUM> while still providing enough filler metal for brazing.

As shown in <FIG>, the first fluid channel of the heat exchanger includes a center flow region <NUM> within the perimeter of the first fluid channel and between an inlet manifold opening and an outlet manifold opening. The copper braze frame <NUM> includes a frame base <NUM> and a frame wall <NUM> that extends from the frame base <NUM> at an angle of at least <NUM> degrees from the base <NUM>. The frame base <NUM> includes an inner edge <NUM>, and the frame wall includes an outer edge <NUM>. The inner edge <NUM> surrounds and defines the area of the center flow region <NUM>. The inner edge <NUM> extends in parallel to the outer edge <NUM> along the perimeter of the first fluid channel at locations W1, W2, L1, L2 where the perimeter is adjacent to the center flow region <NUM>. A width <NUM> of the center flow region <NUM> at the widest point of the center flow region <NUM> is a separation distance between the inner edge <NUM> on one long side L1 of the frame and the inner edge <NUM> on another opposite long side L2 of the frame. A length <NUM> of the center flow region <NUM> at the longest point of the center flow region <NUM> is a separation distance between the inner edge <NUM> on one width side W1 of the frame and the inner edge <NUM> on another opposite width side W2 of the frame. A width dimension of the frame wall <NUM> is greater than or equal to a width dimension of the frame base <NUM> when measured at a point along one of the sides of the copper foil frame - the measurement being taken along a cross-section of the one of the sides of the frame at this point.

<FIG> illustrates an alternative embodiment of the invention of the heat exchanger as previously depicted <FIG>, <FIG>, where the braze joint between the first plate 126a and the second plate <NUM> is made by a braze foil sheet <NUM> of at least partially from copper and arranged between the second plate <NUM> and the third plate 126b, as shown in <FIG> shows similar elements as <FIG>. As shown in <FIG> above, the second plate <NUM> and the third plate 126b form the second fluid channel <NUM> therebetween. Therefore, in this embodiment, the copper-based filler material in the form of the braze foil sheet <NUM> is located in the coolant channel. In the embodiment of <FIG>, the braze foil sheet <NUM> has an outer edge <NUM> that extends beyond an outer edge <NUM> of the second plate, covering at least a contact area between the second plate <NUM> and the third plate 126b. The outer edge <NUM> may be located between the outer edge <NUM> and an outer edge <NUM> of the third plate or may be located at the outer edge <NUM> of the third plate. During a brazing operation for the heat exchanger, the material of the braze sheet <NUM> melts to create a first braze joint 168a between the second plate <NUM> and the third plate 126b. Additionally, the material of the braze sheet <NUM> migrates on the outer of the heat exchanger to create a second braze joint 168b between the second plate <NUM> and the first plate 126a. This embodiment, therefore, further mitigates copper from the braze filler material from entering the first fluid channel and mixing with the first fluid, which may be oil.

In a further embodiment of <FIG>, the heat exchanger <NUM> is manufactured by forming the first plate <NUM> and the second plate <NUM> with bent up side walls, forming the copper braze frame by bending the frame walls at an angle from frame base, and then after bending the frame walls, punching the openings into the frame base. After the first and second plates <NUM>, <NUM> and the braze frame <NUM> are formed. The first and second plates <NUM>, <NUM> are stacked by alternating the first plate <NUM> and the second plate <NUM> with a braze frame stacked between the first plate <NUM> and the second plate <NUM>. Bending of the braze frame <NUM> before punching provides added rigidity to the braze frame <NUM> improving the punching operation and the assembly operation.

Claim 1:
A heat exchanger (<NUM>) comprising:
a first inlet (<NUM>) configured to receive a first fluid;
a first outlet (<NUM>) in fluid communication with the first inlet (<NUM>);
a second inlet (<NUM>) configured to receive a second fluid that includes a coolant;
a second outlet (<NUM>) in fluid communication with the second inlet (<NUM>);
a first plate (<NUM>);
a second plate (<NUM>) stacked on the first plate (<NUM>) to define a first fluid channel (<NUM>) between the first plate (<NUM>) and the second plate (<NUM>), the first fluid channel (<NUM>) providing fluid communication of the first fluid between the first inlet (<NUM>) and the first outlet (<NUM>);
a third plate stacked on the second plate (<NUM>) to define a second fluid channel (<NUM>) between the second plate (<NUM>) and the third plate, the second fluid channel (<NUM>) providing fluid communication of the second fluid between the second inlet (<NUM>) and the second outlet (<NUM>); and
a copper foil frame (<NUM>) between the first plate (<NUM>) and the second plate (<NUM>), the copper foil frame (<NUM>) configured to provide a filler metal for brazing the first plate (<NUM>) to the second plate (<NUM>), wherein the copper frame (<NUM>) extends around a perimeter of the second plate (<NUM>);
characterised in that the copper foil frame (<NUM>) comprises a frame base (<NUM>) with an inner edge (<NUM>), and a frame wall (<NUM>) with an outer edge (<NUM>), wherein the inner edge (<NUM>) surrounds and defines an area of a center flow region (<NUM>) within the first fluid channel (<NUM>), and wherein the inner edge (<NUM>) extends in parallel to the outer edge (<NUM>) at least partially around the center flow region (<NUM>).