CN116772404A

CN116772404A - Heat exchanger, coolant heater and method of forming a heat exchanger body

Info

Publication number: CN116772404A
Application number: CN202210809041.XA
Authority: CN
Inventors: 王之伟; 聂晓倩; 赵德升; 任华清
Original assignee: Litens Automotive Suzhou Co ltd
Current assignee: Litens Automotive Suzhou Co ltd
Priority date: 2022-03-08
Filing date: 2022-07-11
Publication date: 2023-09-19

Abstract

The invention relates to a heat exchanger, a coolant heater and a method of forming a heat exchanger and a body thereof. The heat exchanger includes first and second heat exchanger body portions, a thick film heater, and inlet and outlet headers. The first heat exchanger body portion is continuous and has a plurality of microchannels formed directly thereon. The first heat exchanger body portion and the second heat exchanger body portion cooperate to define a coolant passage with microchannels, each having an inlet and an outlet. The thick film heater is connected to one of the heat exchanger body portions via a thermal conductor material and includes electrical traces and an electrically insulating layer. The traces carry electrical current for heating the coolant in the coolant passages. An insulating layer is between the trace and one of the heat exchanger body portions and prevents current from being conducted from the electrical trace through the electrically insulating layer into one of the heat exchanger body portions at 800V.

Description

Heat exchanger, coolant heater and method of forming a heat exchanger body

Technical Field

The present disclosure relates generally to the field of heat exchangers, and more particularly, to coolant heaters for use in electric vehicles.

Background

Coolant heaters are known in Electric Vehicles (EVs) for the purpose of heating coolant that ultimately circulates through components of the EV that need to be heated for performance reasons, such as the battery of the vehicle. In general, there is a continuing interest in improving the performance and reliability of these devices and at least partially addressing other problems that exist in some coolant heaters that have been used or proposed in the past.

Disclosure of Invention

In one aspect, a heat exchanger is provided and includes a first heat exchanger body portion, a second heat exchanger body portion, a thick film heater, an inlet header, and an outlet header. The first heat exchanger body portion is continuous and has a plurality of microchannels formed directly on the first heat exchanger body portion. The second heat exchanger body portion cooperates with at least the first heat exchanger body portion to define a plurality of coolant passages with the microchannels. Each of the coolant passages has an inlet and an outlet. The thick film heater is connected to at least one of the first heat exchanger body portion and the second heat exchanger body portion via a thermal conductor material. The thick film heater includes electrical traces and an electrically insulating layer. The electrical traces are positioned for carrying electrical current to resistively heat coolant flowing through the coolant passages during use of the heat exchanger. An electrical insulation layer is positioned between the electrical trace and at least one of the first heat exchanger body portion and the second heat exchanger body portion. The electrically insulating layer is sufficiently insulating to prevent conduction of electrical current from the electrical trace through the electrically insulating layer into at least one of the first heat exchanger body portion and the second heat exchanger body portion at 800V. An inlet header is positioned in communication with the inlet of each of the coolant passages. An outlet header is positioned in communication with the outlet of each of the coolant passages.

In another aspect, a coolant heater is provided and includes a first heat exchanger, a first inlet header, a first outlet header, and a controller. The first heat exchanger includes a first heat exchanger body defining a plurality of first coolant passages, and a first electric heater mounted to a first face of the first heat exchanger body and including first electrical traces for carrying a first electrical current to resistively heat coolant flowing through the first coolant passages during use of the first heat exchanger. The first coolant passages each have an inlet and an outlet. The first inlet header is positioned in communication with the inlet of the first coolant passage. The first outlet header is positioned in communication with the outlet of the first coolant passage. The first electric heater extends between the first inlet header and the first outlet header. The controller is positioned adjacent to the second face of the first heat exchanger body. The controller includes a printed circuit board having a first portion with at least one high power device selected from the group of high power devices including microprocessors and IGBTs thereon and a second portion without any high power devices thereon. The printed circuit board is positioned such that a first portion of the printed circuit board is in overlapping relationship with the first inlet header and a second portion of the printed circuit board is in overlapping relationship with the first electric heater.

In yet another aspect, a coolant heater is provided and includes a first heat exchanger and a second heat exchanger. Each of the first and second heat exchangers includes a heat exchanger body defining a plurality of coolant passages, a first electric heater mounted to the heat exchanger body for resistively heating coolant flowing through the coolant passages, and a second electric heater mounted to the heat exchanger body for resistively heating coolant flowing through the coolant passages. The coolant heater also includes a controller operatively connected in parallel to the first electric heater of each of the first and second heat exchangers. The first electric heater of the first heat exchanger is connected in parallel to the second electric heater of each of the first heat exchanger and the second heat exchanger. The first electric heater of the second heat exchanger is connected in parallel to the second electric heater of each of the first and second heat exchangers such that in the event of a failure of either the first or second electric heater or either the first and second heat exchangers, the controller is operable to direct current to all remaining ones of the first or second electric heaters or either the first and second heat exchangers.

In yet another aspect, a coolant heater is provided and includes a heat exchanger and a controller. The heat exchanger includes a heat exchanger body and a first electric heater. The heat exchanger body defines a plurality of coolant passages. The first electric heater is mounted to the heat exchanger body. The first electric heater includes a first electrical trace and a second electrical trace. The second electrical trace has different power consumption or different routing than the first electrical trace. The controller is connected in parallel to the first electrical trace and the second electrical trace and is operable to resistively heat coolant flowing through the coolant passage by driving current through the first electrical trace without transmitting current through the second electrical trace and by driving current through the second electrical trace.

In yet another aspect, a coolant heater is provided and includes a first heat exchanger, a second heat exchanger, and a controller. The first heat exchanger includes a first heat exchanger body defining a plurality of first coolant passages, and a first electric heater mounted to the first heat exchanger body and including first electrical traces for carrying a first electrical current to resistively heat coolant flowing through the first coolant passages during use of the first heat exchanger. The second heat exchanger includes a second heat exchanger body defining a plurality of second coolant passages, and a second electric heater mounted to the second heat exchanger body and including a second electrical trace for carrying a second electrical current to resistively heat coolant flowing through the second coolant passages during use of the second heat exchanger. The controller includes a processor and a memory and is connected in parallel to the first electrical trace and the second electrical trace. The memory contains program code executable by the processor to: operating the controller in a first mode to drive current through the first electrical trace without passing current through the second electrical trace to resistively heat coolant flowing through the first coolant passage; and in a second mode operating the controller to drive current through the second electrical trace to resistively heat coolant flowing through the second coolant passage. The second electrical trace may have different power consumption or different routing than the first electrical trace.

In yet another aspect, a coolant heater is provided and includes a first heat exchanger, a second heat exchanger, a first inlet header, a first outlet header, a second inlet header, and a second outlet header. The first heat exchanger includes a first heat exchanger body defining a plurality of first coolant passages, and a first electric heater mounted to the first heat exchanger body and including first electrical traces for carrying a first electrical current to resistively heat coolant flowing through the first coolant passages during use of the first heat exchanger. The second heat exchanger includes a second heat exchanger body defining a plurality of second coolant passages, and a second electric heater mounted to the second heat exchanger body and including a second electrical trace for carrying a second electrical current to resistively heat coolant flowing through the second coolant passages during use of the second heat exchanger. The first inlet header is positioned in communication with the inlet of the first coolant passage. The first outlet header is positioned in communication with the outlet of the first coolant passage. The second inlet header is positioned in communication with an inlet of the second coolant passage. The second outlet header is positioned in communication with the outlet of the second coolant passage. The first inlet header, the second inlet header, the first outlet header and the second outlet header all have the same size and shape without regard to any apertures therethrough. The first inlet header is adjacent the second outlet header. The first outlet header is adjacent the second inlet header. The first outlet header has at least one first header-to-header aperture and the second inlet header has at least one second header-to-header aperture in fluid communication with the at least one first header-to-header aperture.

In yet another aspect, a coolant heater is provided and includes a first heat exchanger, a second heat exchanger, and a controller. The first heat exchanger includes a first heat exchanger body defining a plurality of first coolant passages, and a first electric heater mounted to a first face of the first heat exchanger body and including first electrical traces for carrying a first electrical current to resistively heat coolant flowing through the first coolant passages during use of the first heat exchanger. The second heat exchanger includes a second heat exchanger body facing the first face of the first heat exchanger body and defining a plurality of second coolant passages, and a second electric heater mounted to the first heat exchanger body and including second electrical traces for carrying a second electrical current to resistively heat coolant flowing through the second coolant passages during use of the second heat exchanger. The controller includes a processor and a memory. The controller is positioned adjacent to the second face of the first heat exchanger body, the second face of the first heat exchanger body facing away from the first face of the first heat exchanger body.

In yet another aspect, a coolant heater is provided and includes a heat exchanger, a controller, and a sensor. The heat exchanger includes a heat exchanger body defining at least one coolant passage, and an electric heater mounted to the heat exchanger body and including electrical traces for carrying an electrical current to resistively heat coolant flowing through the at least one coolant passage during use of the heat exchanger. The controller includes a processor and a memory and is connected to the electric heater. The sensor is for sensing a value of a characteristic of the coolant heater. The memory contains program code executable by the processor to: pulse width modulating at least one of the current and the voltage of the electric heater to bring the value of the characteristic of the coolant heater close to the set point; pulse width modulation at a first frequency when the value of the characteristic of the coolant heater is a first amount from the set point; and pulse width modulating at a second frequency higher than the first frequency when the value of the characteristic of the coolant heater is a second amount from the set point, the second amount being less than the first amount.

In another aspect, a method for forming a heat exchanger body is provided, and includes:

a) Providing a first body plate, a second body plate, and a third body plate positioned between the first body plate and the second body plate, wherein the third body plate includes first and second end portions and a plurality of dividers extending between the first and second end portions, wherein the plurality of dividers are spaced apart from one another to define coolant passages therebetween,

wherein the first end portion, the first end section of the divider immediately adjacent the first end portion, the second end portion, and the second end section of the divider immediately adjacent the second end portion are positioned outside of the first and second body panels, and wherein the cover portion of the divider is sandwiched between the first and second body panels;

b) Joining the plurality of dividers to the first body plate and the second body plate; and

c) At least the first end portion and the second end portion are separated from the cover portion of the separator.

Alternatively, forming the heat exchanger body may be part of a method of forming a heat exchanger. Additional steps for forming the heat exchanger include:

b) Providing an inlet header and mounting the inlet header to the heat exchanger body in fluid communication with at least some of the coolant passages; and

c) An outlet header is provided and mounted to the heat exchanger body in fluid communication with the at least some of the coolant passages.

In another aspect, a coolant heater is provided and includes a first heat exchanger including a first heat exchanger body defining a plurality of first coolant passages and a first electric heater mounted to the first heat exchanger body and including a first electrical trace for resistively heating coolant flowing through the first coolant passages during use of the first heat exchanger. The coolant heater may further include a second heat exchanger including a second heat exchanger body defining a plurality of second coolant passages and a second electric heater mounted to the second heat exchanger body and including a second electrical trace for resistively heating coolant flowing through the second coolant passages during use of the second heat exchanger. The coolant heater may further include a first switching device and a second switching device. The coolant heater may further include a first electrical conduit electrically connecting the first switching device to the first electric heater such that the first switching device is electrically upstream of the first electric heater. The coolant heater may further include a second electrical conduit electrically connecting the second switching device to the second electric heater such that the second switching device is electrically upstream of the second electric heater. The coolant heater may further include third and fourth switching devices. The third electrical conduit electrically connects the first electric heater to the third switching device such that the third switching device is electrically downstream of the first electric heater. The fourth electrical conduit electrically connects the second electric heater to the fourth switching device such that the fourth switching device is electrically downstream of the second electric heater. The fourth electrical conduit electrically connects the second electric heater to the fourth switching device such that the fourth switching device is electrically downstream of the second electric heater. A fifth electrical conduit connects the first and second electrical conduits to each other downstream of the first and second switching devices so as to electrically connect the first switching device to the second electric heater and the second switching device to the first electric heater. The controller comprises a processor and a memory, and the processor (and thus the controller) is operatively connected to the first switching device, the second switching device, the third switching device and the fourth switching device. In a first mode of operation of the coolant heater, the third and fourth switching devices are fully closed, and the first and second switching devices operate to pulse width modulate control the current passing through the first and second electric heaters, respectively. In the event of an open fault of the first switching device while in the first mode of operation, current from the second switching device is transferred through the second electrical conduit to the second electrical heater and through the fifth electrical conduit to the first electrical heater, while the third switching device and the fourth switching device remain fully closed to operate the coolant heater in the second mode of operation. In the event of a closure failure of the first switching device while in the first mode of operation, the processor is programmed to initiate operation of the third switching device and the fourth switching device, for transmission through the fifth electrical conduit to the first electric heater, for operating the coolant heater in the third mode of operation.

Drawings

The foregoing and other aspects of the invention will be better understood with reference to the drawings, in which:

fig. 1 is a perspective view of a coolant heater according to an embodiment of the present disclosure.

Fig. 2 is an exploded perspective view of the coolant heater shown in fig. 1.

Fig. 3 is an exploded perspective view of a heat exchanger that is part of the coolant heater shown in fig. 1.

Fig. 4 is a perspective view of a header from one of the heat exchangers shown in fig. 3.

Fig. 4A is a perspective view of an additional arrangement of headers similar to the header shown in fig. 4, but with apertures.

Fig. 5 is a cross-sectional perspective view of the heat exchanger shown in fig. 2.

Fig. 6 is a cross-sectional perspective view of the heat exchanger shown in fig. 2 with the header as shown in fig. 4A.

Fig. 7 is an exploded view of a header from the heat exchanger shown in fig. 2 and port conduits mated with the header.

Fig. 8A is a cross-sectional view of the heat exchanger shown in fig. 2 with only the header as shown in fig. 4.

Fig. 8B is a cross-sectional view of an alternative embodiment of a heat exchanger having four electric heaters thereon.

FIG. 9 is a graph illustrating characteristics of a coolant heater, such as temperature versus time, and curves illustrating a pulse width modulation strategy for controlling the power of an electric heater as part of the coolant heater to achieve a set point for the characteristics.

Fig. 10A is an electrical schematic diagram showing the connection between IGBTs for controlling the current from the coolant heater to the two electric heaters.

Fig. 10B is an electrical schematic diagram showing a first failure mode of one of the IGBTs shown in fig. 10A.

Fig. 10C is an electrical schematic diagram showing a second failure mode of one of the IGBTs shown in fig. 10A.

Fig. 11 is a schematic diagram showing a controller connected to a plurality of heat exchangers in a combination of series and parallel.

Fig. 12A is a schematic diagram showing a controller connected to two electrical traces in parallel operating in a first mode.

Fig. 12B is a schematic diagram showing a controller connected to two electrical traces in parallel operating in a second mode.

Fig. 12C is a schematic diagram showing a controller connected to two electrical traces in parallel operating in a third mode.

FIG. 13 is a schematic diagram showing a single heat exchanger having a single electric heater thereon, wherein the electric heater has a first electrical trace and a second electrical trace thereon.

Fig. 14 is a schematic diagram showing a single heat exchanger having first and second electric heaters therein, each having an electrical trace thereon.

Fig. 15 is a schematic diagram showing a first heat exchanger and a second heat exchanger having first and second electric heaters thereon, each having an electrical trace thereon.

Fig. 16 is a schematic diagram illustrating a single heat exchanger having first, second and third electric heaters therein, each having electrical traces thereon.

Fig. 17 is an exploded perspective view of components used to form a heat exchanger according to another embodiment of the present disclosure.

Fig. 18 is a perspective view illustrating a step of forming a heat exchanger.

Fig. 19 is a perspective view illustrating another step of manufacturing the heat exchanger.

Fig. 20 is a perspective view illustrating a heat exchanger.

Fig. 21 is a flowchart illustrating a method for forming the heat exchanger also illustrated in fig. 17-20.

Detailed Description

For simplicity and clarity of illustration, where considered appropriate, reference numerals may be repeated among the figures to indicate corresponding or analogous elements. Furthermore, numerous specific details are set forth in order to provide a thorough understanding of one or more embodiments described herein. However, it will be understood by those of ordinary skill in the art that the embodiments described herein may be practiced without these specific details. In other instances, well-known methods, procedures, and components have not been described in detail so as not to obscure the embodiments described herein. It should be understood at the outset that although exemplary embodiments are illustrated in the accompanying drawings and described below, the principles of the present disclosure may be implemented using any number of techniques, whether currently known or unknown. The present disclosure should in no way be limited to the exemplary implementations and techniques illustrated in the accompanying drawings and described below.

Unless the context indicates otherwise, various terms used throughout this specification may be read and understood as follows: as used throughout, the word "or" is inclusive, as if written as "and/or"; as used throughout, the singular articles and pronouns include their plural forms, and the plural articles and pronouns as used throughout include their singular forms; similarly, gender pronouns include their corresponding pronouns, and thus the pronouns should not be construed as limiting anything described herein to use, implementation, execution, etc. by a single gender; "exemplary" should be construed as "illustrative" or "exemplary" and is not necessarily construed as "preferred" over other embodiments. Further definitions of terms may be set forth herein; as will be appreciated from reading the present specification, these definitions may apply to the previous and subsequent examples of those terms.

Modifications, additions, or omissions may be made to the systems, devices, and methods described herein without departing from the scope of the disclosure. For example, components of the systems and devices may be integrated or separated. Moreover, the operations of the systems and devices disclosed herein may be performed by more, fewer, or other components, and the described methods may include more, fewer, or other steps. Furthermore, the steps may be performed in any suitable order. As used in this document, "each" refers to each member of a group or each member of a subgroup of groups.

The singular or plural elements herein are not intended to be limited to the meaning of "a" and "an" of the elements. Where applicable, it is intended to refer to "one or more" of the elements (i.e., unless it is apparent from the context that only one of the elements is appropriate).

Any reference to up, down, top, bottom, etc. is intended to refer to the orientation of a particular element during use of the claimed subject matter, and not necessarily to its orientation during shipping or manufacture. For example, the upper surface of the element may still be considered to be the upper surface of the element even when the element is lying on its side.

Basic component description and use of materials allowing high voltages

Referring to fig. 1, a coolant heater 10 is shown according to an embodiment of the present disclosure. The coolant heater 10 may be used to heat coolant in a thermal management system for an electric vehicle or to heat coolant for any other suitable application. Referring to fig. 2, which is an exploded view of the coolant heater 10, it can be seen that the coolant heater 10 includes at least one heat exchanger 12 and a controller 14. In the embodiment shown in fig. 2, the coolant heater 10 includes a first heat exchanger, indicated at 12a, and a second heat exchanger, indicated at 12 b. In addition, the coolant heater 10 may optionally further include a coolant heater housing 16, which coolant heater housing 16 may be formed of a first coolant heater housing portion 16a and a second coolant heater housing portion 16b, the second coolant heater housing portion 16b being connectable to the first coolant heater housing portion 16a to enclose the at least one heat exchanger 12 and the controller 14.

Referring to fig. 3, an exploded view of the first heat exchanger 12a and the second heat exchanger 12b is shown. Each of the first heat exchanger 12a and the second heat exchanger 12b includes the same components, unless otherwise described. Accordingly, each heat exchanger 12a, 12b includes a heat exchanger body 18, the heat exchanger body 18 defining at least one coolant passage 20 (fig. 4). Optionally, the at least one coolant passage 20 is a plurality of coolant passages 20.

The heat exchanger body 18 may include a first heat exchanger body portion 19a (fig. 3) and a second heat exchanger body portion 19b. The first heat exchanger body portion 19a may include a plurality of microchannels 22 formed directly on the first heat exchanger body portion 19a such that the first heat exchanger body portion 19a is a continuous member. The microchannels 22 may be formed using any known suitable technique, including, but not limited to: micro milling, lithography, stamping, and laser ablation.

The second heat exchanger body portion 19b cooperates with at least the first heat exchanger body portion 19a to define the plurality of coolant passages 20 using microchannels 22. Alternatively (and as shown in fig. 3), the second body portion only cooperates with the first body portion 19a to define the plurality of coolant passages using the microchannels 22. Alternatively, the coolant passage 20 may be defined by cooperation between the first and second heat exchanger body portions 19a, 19b and one or more additional heat exchanger body portions (not shown).

Each of the coolant passages 20 has an inlet 24 and an outlet 26.

The first heat exchanger body portion 19a and the second heat exchanger body portion 19b may be formed of any suitable material. Advantageously, the first heat exchanger body portion 19a and the second heat exchanger body portion 19b may be formed of a material comprising steel. More advantageously, the first heat exchanger body portion 19a and the second heat exchanger body portion 19b may be entirely formed of stainless steel.

Each heat exchanger 12a, 12b also includes an electric heater 28 mounted to the heat exchanger body 18. The electric heater 28 includes electrical traces 30 (indicated by arrows 32 in fig. 3) for carrying electrical current for resistively heating coolant (indicated by arrows 34 in fig. 5) flowing through the coolant passage 20 during use of the heat exchangers 12a, 12 b. The electric heater 28 may be a thick film heater.

The electric heater 28 may be mounted to the heat exchanger body 18 in any suitable manner. For example, the electric heater 28 may be printed directly onto at least one of the first and second body portions 19a, 19b in several layers, including a base electrically insulating layer 29, electrical traces 30 on top of the base electrically insulating layer 29, and a cover electrically insulating layer (not shown, so as not to obscure the electrical traces 30).

Each heat exchanger 12a, 12b further includes an inlet header 36, the inlet header 36 being positioned in communication with the inlet 24 of each of the coolant passages 20.

Each heat exchanger 12a, 12b also includes an outlet header 38, the outlet header 38 being positioned in communication with the outlet 26 of each of the coolant passages 20.

For the first heat exchanger 12a, the heat exchanger body 18, the electric heater 28 (and in particular the base electrical insulation layer 29 and the electrical traces 30), the electrical current 32, the inlet header 36, and the outlet header 38 may all be referred to as the first heat exchanger body 18a, the first electric heater 28a, the first base electrical insulation layer 29a, the first electrical trace 30a, the first electrical current 32a, the first inlet header 36a, and the first outlet header 38a.

For the second heat exchanger 12b, the heat exchanger body 18, the electric heater 28, the base electrically insulating layer 29, the electrical traces 30, the electrical current 32, the inlet header 36, and the outlet header 38 may all be referred to as a second heat exchanger body 18b, a second electric heater 28b, a second electrical trace 30b, a second electrical current 32b, a second inlet header 36b, and a second outlet header 38b.

By fabricating the heat exchanger body 18 from a material comprising steel (e.g., stainless steel) or alternatively entirely from steel, the heat exchanger body 18 is able to withstand current at a higher voltage (e.g., about 800V) than can be withstand when the heat exchanger body 18 is made from aluminum. The reason for this is related to the base electrically insulating layer 29. In some embodiments, the base electrically insulating layer 29 is made of a material that is initially applied to the heat exchanger body 18 in a non-solid form. The base electrically insulating layer 29 is then heated to cure the base electrically insulating layer 29. For some types of base electrically insulating layer 29, it has been found that if the temperature at which the base electrically insulating layer 29 is heated is too low, it does not cure in a manner that provides good performance as an electrical insulator. Conversely, if the base electrically insulating layer 29 is heated to a temperature of at least about 800 degrees celsius (e.g., 850 degrees celsius) and held there for an appropriate amount of time (e.g., about 10 minutes), the base electrically insulating layer 29 cures in a manner that provides strong performance as an electrical insulator. Thus, the base electrically insulating layer 29 may be sufficiently insulating to prevent electrical current from conducting from the electrical trace 30 through the base electrically insulating layer 29 into at least one of the first heat exchanger body portion 19a and the second heat exchanger body portion 19b at 800V. This allows the full voltage from the vehicle battery to be used in heating the coolant passing through the coolant passage 20. In contrast, as described above, if the base electrically insulating layer 29 is heated to a lower temperature, the performance of the base electrically insulating layer 29 as an electrical insulator may be deteriorated. Thus, current at 800V will leak through the base electrically insulating layer 29. In the prior art, many proposed coolant heaters include an aluminum heat exchanger body due to the relatively high thermal conductivity associated with aluminum, as well as the relatively low cost of aluminum, the machinability of aluminum, and the light weight of aluminum. However, the melting point of aluminum prevents the use of a base electrically insulating layer 29 that is heated to 800 degrees celsius or higher. However, by providing the first heat exchanger body portion 19a and the second heat exchanger body portion 19b made of stainless steel, the base electrically insulating layer 29 can be heated to 800 degrees celsius without damaging the first heat exchanger body portion 19a and the second heat exchanger body portion 19b.

A suitable material for the base electrically insulating layer 29 may be a suitable glass dielectric material.

In some embodiments, the coolant heater 10 shown in the figures is capable of receiving a higher power input current per unit area of the heat exchanger 12 than some examples of the prior art. In some embodiments, the coolant heater 10 is capable of receiving up to 15kW of power that may be directed to the coolant, and may have an effective area of 332cm 2 in the first and second heat exchanger bodies 18a, 18 b.

While the use of materials for the electrically insulating layer 29 may be as described above, for which it is beneficial to form the heat exchanger body portions 19a and 19b from stainless steel, the following materials for the electrically insulating layer 29 may also be provided: the material may be treated at a sufficiently low temperature so that the heat exchanger body portions 19a and 19b may be made of aluminum or some other metal having a melting temperature lower than that of stainless steel. In still other embodiments, the heat exchanger body portions 19a and 19b may be formed from some other material, such as ceramic, alumina ceramic, or copper.

Construction using standardized parts to reduce inventory

Referring to fig. 4, elements representing each of the first inlet header 36a, the second inlet header 36b, the first outlet header 38a, and the second outlet header 38b are shown. Alternatively, as shown in fig. 4, the first inlet header 36a, the second inlet header 36b, the first outlet header 38a, and the second outlet header 38b all have the same size and shape without regard to any apertures therethrough (i.e., without counting any apertures that may be present in them). For example, all of these headers 36a, 36b, 38a and 38b may be formed from the same rectangular tube section, indicated at 40. Each section 40 has a cover 42 that encloses a first end 44 of the section 40 and has an open second end 46. A slot 48 is provided along a side wall 50 of the section 40. By positioning the slots 48 equidistant between the first and second ends 44, 46 and equidistant between the top and bottom surfaces 52, 54, the segments 40 can be oriented as desired to function as each of the headers 36a, 36b, 38a, 38b while all having the same size and shape.

By manufacturing the heat exchanger using headers 36a, 36b, 38a, and 38b that are all the same size and shape, the manufacturer needs to store fewer different types of parts in inventory and less chance of error during the manufacture of the heat exchanger.

To assemble each heat exchanger 12, the heat exchanger body 18 may be assembled and the heat exchanger body 18 may be inserted into the slots 44 in the inlet header 36 and the outlet header 38. The inlet header 36 and the outlet header 38 may be welded or otherwise sealingly joined to the heat exchanger body 18. Alternatively, the first and second heat exchanger body portions 19a, 19b may not be fixedly connected to each other prior to insertion into the grooves 44 in the inlet and outlet headers 36, 38 so that the components may be welded or otherwise joined together.

Furthermore, some of the headers 36a, 36b, 38a, 38 may be provided with an arrangement of at least one header-to-header aperture 56, as shown in fig. 4A. This allows for a first heat exchanger and second heat exchanger configuration as shown in fig. 6, wherein the first inlet header 36a is adjacent the second outlet header 38b, and wherein the first outlet header 38a is adjacent the second inlet header 36b, and wherein the first outlet header 38a has at least one first header-to-header aperture 56 and the second inlet header 36b has at least one second header-to-header aperture 56 in fluid communication with the at least one first header-to-header aperture 56. By forming the arrangement of at least one header-to-header aperture 56 equidistant from the first end 44 and the second end 46 and equidistant from the first sidewall and the second sidewall (represented by 50 and 58), the two headers 38a and 36b may be the same size and shape and may be a single inventory item of the manufacturer of the coolant heater 10.

As shown in fig. 6, the headers 36a, 36b, 38a, 38b may be sized to form a square when stacked in pairs as shown. In other words, each header 36a, 36b, 38a, 38b may have a width W that is twice the height of the header, indicated as H. Thus, the header may be joined at its respective second end 46 to a port conduit 60, which port conduit 60 is circular and has a square flange 62. Providing the port conduit 60 with a circular conduit facilitates connecting the port conduit 60 to other conduits in the thermal management system of the vehicle.

Fig. 3 also shows a cover plate, indicated at 64 and 66, that includes a region between heat exchanger 12a and heat exchanger 12b where first electric heater 28a and second electric heater 28b are located. In addition, fig. 3 shows a support bracket 68, which support bracket 68 may be used to facilitate mounting of the heat exchangers 12a and 12b to lugs 70 (fig. 2) in the housing 16 of the coolant heater 10.

Flow disturbance device

In an embodiment, as shown in fig. 5, 6 and 8, the first inlet header 36a has an internal width Wi and an internal height Hi. The coolant heater 10 further includes a flow perturbating means 72 positioned in the first inlet header 36a to perturb the coolant flow 34 in the first inlet header 36a to reduce any temperature gradient in the coolant flow 34 across a cross-sectional area of the coolant flow 34 in the first inlet header 36 a. As shown in fig. 5 and 8, each of the first inlet header 36a and the second inlet header 36b may have a flow perturbation device 72. The flow perturbation device 72 may include a plate mounted into the inlet header 36 where the flow perturbation device 72 is to be used and a plurality of cylinders extending across a selected amount of the internal width Wi and the internal height Hi. In the illustrated embodiment, the flow perturbation device 72 is positioned at least partially in a central portion of the inlet header 36. The central portion of the inlet header 36 is shown by the dashed rectangle 74 and extends across 50% of the interior width Wi and extends across 50% of the interior height Hi.

Positioning heater and PCB to keep heat inside and keep PCB cool

As shown in several of the figures, the electric heater 28 is mounted to a first face 76 of the heat exchanger body 18, and the controller 14 (fig. 8A) is mounted adjacent a second face 78 of the heat exchanger body 18 opposite the first face 76. Thus, the heat generated by the electric heater 28 is at least partially maintained away from the controller 14. In addition, as shown in fig. 2, the controller 14 includes a Printed Circuit Board (PCB) 80, the PCB80 including a first portion 80a having at least one high power device 79 thereon. The at least one high power device 79 may comprise any suitable type of high power device, such as a processor or a switching device. Examples of suitable switching devices include IGBTs denoted by 81. Thus, in at least some embodiments, the at least one high power device 79 may be at least one device selected from the group of devices consisting of a processor and a switching device. In this example, there are four IGBTs 81 on the PCB80, all of which are considered high power devices. In this example, PCB80 includes a processor 83, but in this particular embodiment, the processor is not considered a high power device 81. The PCB80 also includes a second portion 80b that does not have any high power devices thereon. As shown in fig. 8A, the PCB80 is positioned such that a first portion 80a of the printed circuit board 80 is in overlapping relationship with the first inlet header 36a and such that a second portion 80b of the printed circuit board 80 is in overlapping relationship with the first electric heater 28A. The first electric heater 28a can be seen extending between a first inlet header 36a and a first outlet header 38 a. For the sake of clarity, it should be noted that the second portion 80b of the printed circuit board 80 may include some components thereon, and even though no components are shown on the second portion 80b in fig. 8A, there are several components shown thereon in fig. 2, such as, for example, the processor 84.

By positioning the first portion 80a of the PCB 80 in overlapping relation with the inlet header 36a, the high power device 81 remains cooler than the second portion 80b of the PCB 80 that overlaps the first electric heater 28 a. Furthermore, a thermal conductor 82 may be provided and the thermal conductor 82 is engaged with both the printed circuit board 80 and the first inlet header 36a to increase the heat transferred from the high power device 79 to the coolant 34 in the inlet header 36 a. Advantageously, the flow perturbation device 72 is positioned such that the first portion 80a of the PCB 80 is in overlapping relationship with the flow perturbation device 72, thereby further improving the heat transfer efficiency away from the first portion 80a of the PCB 80.

The controller 14 also includes a processor 83 and a memory 84, the processor 83 and the memory 84 being mountable to the PCB 80. The memory 84 of the controller 14 stores program code that can be executed by the processor. In this disclosure, when describing certain method steps that the controller 14 is programmed to perform, it is intended that the memory 84 contain program code that can be executed by the processor 83 to perform those method steps. Memory 84 may be any suitable type of memory that may contain information such as data and program code readable by processor 83.

In the illustrated embodiment, the first and second heat exchangers 12a, 12b are positioned such that the first face 76 of the first heat exchanger body 18a faces the first face 76 of the second heat exchanger body 18b, such that the first and second electric heaters 28a, 28b are positioned between the first and second heat exchanger bodies 18a, 18b, and such that the second face 78 of the first heat exchanger body 18a faces away from the second face 78 of the second heat exchanger body 18 b.

Alternatively, an embodiment may be provided in which the first electric heater 28a is on the first face 76 of the first heat exchanger body 18a and the second electric heater 28b is on the second face 78 of the second heat exchanger body 18 b. In such alternative embodiments, the controller 14 may remain mounted adjacent to the second face 78 of the first heat exchanger body 18 a.

As yet another alternative, an embodiment may be provided in which the first electric heater 28a is on the first face 76 of the first heat exchanger body 18a, the second electric heater 28b is on the first face 78 of the second heat exchanger body 18b, and the third electric heater is on the second face 78 of the second heat exchanger body 18 b. In such alternative embodiments, the controller 14 may remain mounted adjacent to the second face 78 of the first heat exchanger body 18 a.

In some embodiments, the first electric heater 28a may be disposed on the second face 78 of the first heat exchanger body 18a, which would position the first electric heater 28a in overlapping relationship with the controller 14. In order to reduce heat transfer from the first electric heater 28a to the controller 14, a reflective member may be provided between the controller 14 and the first electric heater 28a to reflect heat from the first electric heater 28a back toward the first electric heater 28a. Fig. 8B shows a reflective member, indicated at 99, mounted to the outlet header 38 a. In addition, fig. 8B shows the first electric heater 28a located on the second face 78 of the first heat exchanger body 18 a. By providing the reflecting member 99, it is possible (as shown in the drawing).

B) Four electric heaters 28 are provided for the coolant heater 10, including electric heaters 28 (identified as first, second, third, and fourth electric heaters 28a, 28b, 28c, 28 d) located on each of the first and second faces 76, 78 of each of the first and second heat exchanger bodies 18a, 18 b. For greater clarity, the first electric heater 28a may be disposed on either the first face 76 or the second face 78 of the first heat exchanger 12 a. If provided on the second face 76, the reflective member 99 is preferably provided between the first electric heater and the controller 14. The second electric heater 28b may be disposed on either the first face 76 or the second face 78 of the second heat exchanger 12 b. The third electric heater 28c is not required, but if the third electric heater 28c is provided, the third electric heater 28c may be located on the opposite side of the first side 76 or the second side 78 of the first heat exchanger 12a from the side having the first electric heater 28 a. Similarly, there need not be a fourth electric heater 28d, but if a fourth electric heater 28d is provided, the fourth electric heater 28d may be located on the opposite of the first face 76 or the second face 78 of the second heat exchanger 12b from the face having the second electric heater 28 b.

While the embodiment in fig. 8B shows the first and second heat exchangers 12a, 12B with coolant flow parallel, it should be appreciated that the first and second heat exchangers 12a, 12B may be arranged as shown in fig. 6 such that coolant flow is instead serially through the first and second heat exchangers 12a, 12B, while still providing two, three, or four electric heaters 28 on the first and second heat exchangers 12a, 12B as described above.

Controlling characteristics using PWM with adjustable frequency

Referring to fig. 9, a graph of a characteristic of the coolant heater 10, such as a time-dependent temperature of a sensor 86 (fig. 10A) based on a value for sensing the characteristic of the coolant heater 10, is shown. Using a plurality of IGBTs 81 as shown in fig. 10A, the plurality of IGBTs 81 being shown as a first IGBT 81a, a second IGBT 81b, a third IGBT 81c, and a fourth IGBT 81d, respectively, the controller 14 is programmed to Pulse Width Modulate (PWM) at least one of the current and voltage of the first electric heater 28a and the second electric heater 28b to bring the value of the characteristic of the coolant heater close to the setpoint (indicated at 88 in fig. 9).

Curve 89 is the value of the characteristic. The controller 14 is programmed to perform PWM, indicated at 90 in fig. 9, at a first frequency F1 when the value of the characteristic of the coolant heater 10 is a first amount (D1) from the setpoint 88, F1 being equal to 1/T1, where T1 is the period of PWM. As shown, the controller 14 is programmed to PWM (indicated at 92) at a second frequency F2 (which is equal to 1/T2, where T2 is the period of PWM) when the value of the characteristic of the coolant heater 10 is a second amount D2 from the setpoint 88, the second amount D2 being less than the first amount D1. As can be observed, the second frequency F2 is higher than the first frequency F1.

In some embodiments, the controller 14 is programmed to adjust the frequency of the PWM step by step between the first frequency F1 and the second frequency F2 based on the difference in the value of the characteristic from the setpoint 88. The controller 14 may be programmed to adjust the frequency of the PWM step by step or more preferably continuously.

In some embodiments, the target temperature of the coolant may be about 90 degrees celsius. In other embodiments, the target temperature of the coolant may be about 60 degrees celsius. In still other embodiments, the target temperature of the coolant may be some other value.

Positioning IGBTs to provide redundancy for each other

A number of different ways of connecting the controller 14 to the heat exchanger 12 may be provided. For example, in the embodiment shown in fig. 10A, there is: a first switching device (e.g., a first IGBT 81 a) and a second switching device (e.g., a second IGBT 81 b), the first electrical conduit 110 electrically connects the first switching device to the first electric heater 28a such that the first switching device is electrically upstream of the first electric heater 28a, and the second electrical conduit 112 electrically connects the second switching device to the second electric heater 28b such that the second switching device is electrically upstream of the second electric heater 28 b; a third switching device (e.g., a first IGBT 81 c) and a fourth switching device (e.g., a fourth IGBT 81 d), a third electrical conduit 114 electrically connects the first electric heater 28a to the third switching device such that the third switching device is electrically downstream of the first electric heater, and a fourth electrical conduit 116 electrically connects the second electric heater 28b to the fourth switching device such that the fourth switching device is electrically downstream of the second electric heater 28b, and a fifth electrical conduit 118 connects the first and second electrical conduits 110 and 112 to each other downstream of the first and second switching devices so as to electrically connect the first and second switching devices 81a to the second electric heater 28b and 81b to the first electric heater. The processor 83 of the controller 14 may be connected to the first switching device, the second switching device, the third switching device and the fourth switching device.

In the first operation mode of the coolant heater 10, the third and fourth switching devices are fully closed, and the first and second switching devices operate to perform pulse width modulation control of the current transmitted through the first and second electric heaters 28a and 28b, respectively. In the event of an open fault of the first switching device while in the first mode of operation, the processor 83 is programmed such that current from the second switching device is transmitted to the second electric heater 28b through the second electrical conduit 112 and to the first electric heater 28a through the fifth electrical conduit 118, while the third and fourth switching devices remain fully closed to operate the coolant heater 10 in the second mode of operation. In addition, in the event of a closure failure of the first switching device while in the first mode of operation, the processor 83 is programmed to cause the processor to initiate operation of the third and fourth switching devices to perform pulse width modulation control of the current passing through the first and second electric heaters 28a, respectively, to operate the coolant heater in the third mode of operation. When a first switching device fails to close, it will be appreciated that current is transferred from the first switching device that fails to close through the first electric heater 28a by means of the first electrical conduit 110 and possibly from the first switching device that fails to close through the second electric heater 28b by means of the fifth electrical conduit 118, or alternatively, the second switching device may be kept closed by the processor 83 in a third mode of operation so as to transfer the current of both the first and second switching devices to the first and second electric heaters 28a and 28b, respectively.

Since IGBTs may generally be points of failure on the devices to which they are connected, the above arrangement allows operation of both electric heaters 28a and 28b even in the event of an open failure of one of IGBTs 81, and also in the event of a closed failure of one of the IGBTs.

Electric heater and optional layout of its circuit

A number of different ways of connecting the controller 14 to the heat exchanger 12 may be provided. Referring to fig. 11, 12A and 12B, the controller 14 is shown connected to various electric heaters 28 in various ways. Fig. 11 shows that the controller 14 is connected to the first electric heater 28a, the second electric heater 28b, the third electric heater 28c, and the fourth electric heater 28d in a combination of series and parallel, wherein the first electric heater 28a and the second electric heater 28b are positioned on the first heat exchanger 12a, and the third electric heater 28c and the fourth electric heater 28d are positioned on the second heat exchanger 12 b. As shown in fig. 14, each of the heat exchangers 12a and 12b may be constructed similarly to that shown in fig. 2 to 5, except that the first heat exchanger 12a includes two electric heaters 28 instead of one electric heater, and the second heat exchanger 12b includes two electric heaters 28 instead of one electric heater. Thus, each of the first and second heat exchangers 12a, 12b includes a heat exchanger body 18 defining a plurality of coolant passages 20, and includes a first electric heater 28a mounted to the heat exchanger body 20 and a second electric heater 28b also mounted to the heat exchanger body 20.

As can be observed, the controller 14 in fig. 11 is connected in parallel with the first electric heater 28a of each of the first and second heat exchangers 12a, 12b, the first electric heater 28a of the first heat exchanger 12a being connected to the second electric heater 28b of the first heat exchanger 12a and in parallel with the second electric heater 28b of the second heat exchanger 12b, and similarly, the first electric heater 28a of the second heat exchanger 12b being connected to the second electric heater 28b of the first heat exchanger 12a and in parallel with the second electric heater 28b of the second heat exchanger 12b, such that in the event of a failure of any one of the first and second electric heaters 28a, 28b of one of the first and second heat exchangers 12a, 12b (i.e., a failure of one of the first and second electric heaters 28a, 28b that is unable to carry current therethrough) the controller 14 is operable to conduct current from the first and second heat exchanger 12a to all of the remaining first and second electric heaters 28a, 28 b. This may be accomplished using any suitable structure, such as by connecting the first electric heater 28a of each of the first and second heat exchangers 12a, 12b in series with the second electric heater 28b via the first and second transfer conduits 100, 102, respectively, and by connecting the first and second transfer conduits 100, 102 via the third transfer conduit 104.

Fig. 13 shows a heat exchanger 12. The heat exchanger 12 may also have a somewhat similar structure to the configuration shown in fig. 2-5. Accordingly, the heat exchanger may include a heat exchanger body 18 defining a plurality of coolant passages 20 and an electric heater 28 mounted to the first heat exchanger body 18. However, as shown in fig. 13, the electric heater 28 may include a first electrical trace 106 and a second electrical trace 108, wherein the second electrical trace 108 has different power consumption and/or different routing than the first electrical trace 106. Fig. 12A and 12B illustrate the controller 14 connected to the first electrical trace portion 106 and the second electrical trace portion 108. The memory 84 of the controller 14 may contain program code that is executable by the processor 14 to:

in a first mode the controller 14 is operated to resistively heat coolant flowing through the coolant passage 20 by driving current through the first electrical trace 106 without passing current through the second electrical trace 108, (illustrated in fig. 12A as having an X in the IGBT 81 connected to the second electrical trace 108, indicating no current flowing, and having no X in the IGBT 81 connected to the first electrical trace 106, indicating current flowing), and

The controller 14 is operable in the second mode to resistively heat coolant flowing through the first coolant passage 20 by driving current through the second electrical trace 108.

In an embodiment, fig. 12B may illustrate a second mode of operation of the controller 14. As can be observed in fig. 12B, the controller 14 may operate in the second mode to resistively heat the coolant flowing through the coolant passage 20 by driving current through the second electrical trace 108 without passing current through the first electrical trace 106. Further, the controller 14 may be operable in a third mode (as shown in fig. 12C) to resistively heat the coolant flowing through the coolant passage 20 by driving current through the second electrical trace 108 and through the first electrical trace 106. In an alternative embodiment, the operation shown in fig. 12C may be considered the second mode of operation of the controller 14.

In the case where a heat exchanger 12 having a single electric heater 28 with two electrical traces 106 and 108 can be provided as shown in fig. 13, in some embodiments, a heat exchanger 12 having a first electric heater 28a and a second electric heater 28b can be provided, where the first electric heater 28a has a first electrical trace 106 and the second electric heater 28b has a second electrical trace 108.

In general, where electrical traces have been represented at 106 and 108, each of these electrical traces may be similar to electrical trace 30 shown in any of the figures. Where a single electric heater 28 contains both the first electrical trace 106 and the second electrical trace 108 (as shown in fig. 13), there may be a single base electrical insulation layer 29 that isolates current leakage from both the first electrical trace 106 and the second electrical trace 108. In the case where there are two electric heaters 28a and 28b, each of which contains one of the first electrical trace 106 and the second electrical trace 108 (as shown in fig. 14), there may be a base electrically insulating layer 29 in each electric heater 28a or 28b that isolates current leakage from the associated first electrical trace 106 or second electrical trace 108.

It will be noted that the direction of the coolant passages 20 in fig. 13 may be oriented laterally (i.e., parallel to the directional arrow shown at 150 in the figure). Thus, the coolant passage 20 of the heat exchanger 12 shown in fig. 13 passes through both of the electric heaters 28a and 28b.

In contrast, in the embodiment shown in fig. 14, the direction of coolant passages 20 in fig. 14 may be oriented vertically on the page (i.e., parallel to the directional arrow shown at 152 in the figure). Thus, some of the coolant passages 20 of the heat exchanger 12 shown in fig. 14 pass through one of the electric heaters 28a, but not through the other of the electric heaters 28b, and some of the coolant passages 20 pass through the other of the electric heaters 28b. Such a configuration may be advantageous in embodiments where the flow through a first subset of coolant passages 20 (which pass through first electric heater 28 a) is lower than the flow in a second subset of coolant passages 20 (which pass through first electric heater 28 b).

In some embodiments, there may be a heat exchanger 12 having three or more electrical traces oriented so as to provide a combination of orientations shown in fig. 13 and 14, an example of which is shown in fig. 16. Thus, at least one of the electrical traces (indicated at 106) is oriented such that all of the coolant channels 20 pass through the trace, and at least two of the electrical traces (indicated at 107 and 108) are oriented such that only a first portion 109a of the coolant channels 20 passes through a first one of the electrical traces 107 or 108, and such that a second portion 109b of the coolant channels 20 passes through a second one of the electrical traces 107 or 108.

In any of the embodiments described or illustrated, only some of the coolant channels 20 pass through one of the electrical traces 107 or 108 and such that only the first portion 109a of the coolant channels 20 passes through a first one of the electrical traces 107 or 108 and such that the second portion 109b of the coolant channels 20 passes through a second one of the electrical traces 107 or 108, the particular thermal energy generated by each of the first and second electrical traces 107 and 108 may be selected for a particular flow of coolant through the first and second portions 109a and 109b of the coolant channels 20. For example, the coolant channels 20 may all have the same width, but channels distal to the inlet port (inlet port indicated at 200) of the inlet header 36 may have a smaller amount of coolant flowing therethrough than channels proximal to the inlet port 200. Thus, the specific average flow rate of coolant for the coolant channels 20 in the first portion 109a (the first portion 109a being remote from the inlet port 200) may be lower than the specific average flow rate of coolant for the coolant channels 20 in the second portion 109b (the second portion 109b being closer to the inlet port 200 than the first portion 109a of the coolant channels 20). For greater clarity, the specific coolant flow may be the coolant flow per unit area of the heat exchanger (e.g., per cm 2 of the heat exchanger 12). Thus, even though the coolant channels 20 in the first and second portions 109a, 109b may have the same width and the same spacing, the specific coolant flow in the second portion 109b may be a percentage higher than the specific coolant flow in the first portion 109 a. In this regard, the second electric heater 28b may have a certain percentage higher specific energy output than the first electric heater 28a, preferably a similar percentage to the percentage increase (e.g., within 10%) of the specific average coolant flow between the first portion 109a and the second portion 109b of the coolant channel 20. The specific energy output of the electric heater is the energy output per unit area of the electric heater (e.g., per cm 2 of the electric heater 28).

Referring to fig. 15, the following embodiments may be provided: in this embodiment, the coolant heater includes: a first heat exchanger 12a and a first electric heater 28a, the first heat exchanger 12a including a first heat exchanger body 18 (as shown in fig. 2-5) defining a plurality of first coolant passages 20, the first electric heater 28a being mounted to the first heat exchanger body 18, and the first electric heater 28a including a first electrical trace 106 for carrying a first electrical current for resistively heating coolant flowing through the first coolant passages 20 during use of the first heat exchanger 12 a; and a second heat exchanger 12b and a second electric heater 28b, the second heat exchanger 12b including a second heat exchanger body 18 defining a plurality of second coolant passages 20, the second electric heater 28b being mounted to the second heat exchanger body 18, and the second electric heater 28b including a second electrical trace 108 for carrying a second electrical current for resistively heating coolant flowing through the second coolant passages 20 during use of the second heat exchanger 12 b. The controller 14 is connected in parallel with the first electrical trace 106 and the second electrical trace 108, and the memory 84 of the controller 14 contains program code executable by the processor 83 to:

Operating the controller 14 in the first mode to drive current through the first electrical trace 106 without passing current through the second electrical trace 108 to resistively heat the coolant flowing through the first coolant passage 20; and

the controller 14 is operated in the second mode to drive current through the second electrical trace 108 to resistively heat coolant flowing through the second coolant passage.

Fig. 15 specifically schematically illustrates the heat exchangers 12a and 12b. It will be appreciated that the actual heat exchangers will be positioned facing each other in a similar manner to that shown in fig. 2-8.

The embodiment shown in fig. 15 may be similar to the embodiment shown in fig. 2-5, but explicitly shows that the first electrical trace 29a has a different routing and that the first electrical trace 29a may have a different power consumption than the second electrical trace shown at 29 b. Thus, referring to fig. 6, the coolant flowing through the first coolant passage (indicated at 20a in fig. 6) can flow in series with the coolant flowing through the second coolant passage (indicated at 20b in fig. 6). Referring to fig. 8A, the coolant flowing through the first coolant passage (indicated at 20a in fig. 8A) can flow in series with the coolant flowing through the second coolant passage (indicated at 20b in fig. 8A).

Reduction of inductance

Fig. 15 also illustrates one strategy for reducing inductance in electrical traces 106 and 108. In fig. 15, the first electrical trace 106 and the second electrical trace 108 may have the same power consumption but different routing such that the electrical trace 106 and the electrical trace 108 are perpendicular to each other along portions of the routing of the electrical trace 106 and the electrical trace 108 (e.g., trace sections 111 and 113), thereby reducing any inductance that would be created if both the electrical trace 106 and the electrical trace 108 were parallel to each other.

Fig. 3 also illustrates another way of reducing inductance, wherein the layout of the electrical traces (indicated at 30) is the same. In fig. 3, the direction of current 32a may be opposite to the direction of current 32b such that the inductance created between electrical traces 30 of electric heaters 28a and 28b is reduced.

Other possible configurations besides the configuration of the electric heater 28, heat exchanger 12 and electrical traces 30 shown herein are also possible.

Alternative method for forming channels

In the above description, several ways of forming the heat exchanger 12 are described. An alternative method for forming the heat exchanger 12 is illustrated in fig. 17-20. Fig. 17 is an exploded view of components for the manufacture of heat exchanger 12, including: a first body plate 120, a second body plate 122, a third body plate 124, an inlet header 36, an outlet header 38, and an electric heater 28. The first body plate 120, the second body plate 122, and the third body plate 124 are used to form the heat exchanger body 18. The third body plate 124 includes a first end portion 126, a second end portion 128, and a plurality of dividers 130 extending between the first end portion 126 and the second end portion 128. The plurality of dividers 130 are spaced apart from one another to define coolant passages 132 between the plurality of dividers. The third body plate 124 itself may be manufactured by any suitable operation, such as by stamping or any other suitable means, to provide the spacers 130 spaced apart from one another. Furthermore, the separator 130 may have any suitable shape, for example, the separator 130 may be in the form of a rectangular bar, or a triangular bar, or any other suitable shape.

Fig. 18 shows the completion of the first step of the method, which is to arrange the first body plate 120, the second body plate 122 and the third body plate 124 such that the third body plate 124 is located between the first body plate 120 and the second body plate 122. The first end portion 126, the first end section 134 of the divider 130 proximate the first end portion 126, the second end 128 portion, and the second end section 136 of the divider 130 proximate the second end portion 128 are positioned outboard of the first body panel 120 and the second body panel 122, with the cover portion 137 of the divider 130 interposed between the first body panel 120 and the second body panel 122.

In a subsequent step, a plurality of spacers are coupled to the first body plate 120 and the second body plate 122. This may be achieved by brazing each divider 130 to both the first body plate 120 and the second body plate 122, respectively. Alternatively, this may be achieved by separately joining some of the dividers 130 to both the first body plate 120 and the second body plate 122, while separately joining some of the dividers 130 to one or the other of the first body plate 120 and the second body plate 122. Alternatively, any other suitable scheme for joining the separator 130 to the first and second body plates 120 and 122 may be used.

Fig. 19 shows the completion of the third step of the method, the second step separating at least the first end portion 126 and the second end portion 128 from the cover portion 137 of the divider 130. As shown in fig. 19, this may also require separating the first and second end sections 134, 136 of the separator 130 from the cover portion 137 of the separator 130. This may be done by a suitable cutting process, such as laser cutting or by mechanical cutting. In some embodiments, completion of this step results in the heat exchanger body 18. Thus, the above steps may be considered as steps of a method for forming a heat exchanger body.

Fig. 20 illustrates the completion of additional steps for forming the heat exchanger 12 after the steps for forming the heat exchanger body 18 are performed. The subsequent step is to provide an inlet header 36 and mount the inlet header 36 to the heat exchanger body 18 in fluid communication with at least some of the coolant passages 132. Another subsequent step is to provide the outlet header 38 and mount the outlet header 38 to the heat exchanger body 18 in fluid communication with at least some of the coolant passages 132. More specifically, it will be noted that the step of positioning and mounting the inlet header 36 may be performed before, during, or after the step of positioning and mounting the outlet header 38. Mounting the inlet header 36 and the outlet header 38 to the heat exchanger body 18 may be accomplished by brazing or by any other suitable process. In an embodiment, the materials of construction of the first body plate 120, the second body plate 122, and the third body plate 124 are all stainless steel. Alternatively, any other suitable construction material may be used, such as aluminum or any other suitable material. Another subsequent step is to mount the electric heater 28 to one of the first body plate 120 and the second body plate 122. Mounting the electric heater 28 may occur before, during, or after mounting one or more of the inlet header 36 and the outlet header 38.

Fig. 21 illustrates the method steps described above. As can be observed, the method for forming the heat exchanger is identified at 140. Step 142 is a step of disposing the first body plate 120, the second body plate 122, and the third body plate 124, wherein the cover portion of the separator 130 of the third body plate 124 is interposed between the first body plate 120 and the second body plate 122 as described above. Step 144 is a step of joining the separator to the first body plate 120 and the second body plate 122. Step 146 is a step of separating the first end portion 126 and the second end portion 128 from the cover portion 137 of the partition 130 to create the heat exchanger body 18. Step 148 is the step of providing and mounting the inlet header 36 to the heat exchanger body 18. Step 150 is a step of disposing and mounting the outlet header 38 to the heat exchanger body 18. Step 152 is a step of applying the electric heater 28 to one of the first body plate 120 and the second body plate 122.

Description of other alternatives

While separate inlet headers 36a and 36b are shown for each heat exchanger 12a, 12b, it will be appreciated that a single larger inlet header may be provided that is square in cross-section or round in cross-section and that is connected to both heat exchanger bodies 18a and 18 b.

Although the coolant passages 20 have been shown as being straight, it will be noted that the coolant passages 20 may alternatively have any other wiring, such as undulating wiring.

While the electric heater 28 has been described as a thick film heater, the electric heater 28 may alternatively be any other suitable type of resistance-based heater, such as a PTC heater.

Although the coolant heater housing 16 is not shown as including any insulation therein, some insulation may alternatively be provided to reduce the amount of heat lost to the surrounding environment during operation of the coolant heater 10. Any suitable type of insulating material may be used if provided.

While the description contained herein constitutes a number of embodiments of the invention, it will be appreciated that the invention is susceptible to further modifications and variations without departing from the fair meaning of the accompanying claims.

List of reference numerals

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Claims

1. A heat exchanger, comprising:

a first heat exchanger body portion, wherein the first heat exchanger body portion is continuous and has a plurality of microchannels formed directly on the first heat exchanger body portion;

A second heat exchanger body portion cooperating with at least the first heat exchanger body portion to define a plurality of coolant passages with the microchannels, each of the coolant passages having an inlet and an outlet;

a thick film heater connected to at least one of the first heat exchanger body portion and the second heat exchanger body portion via a thermal conductor material, and comprising:

an electrical trace for carrying an electrical current to resistively heat coolant flowing through the coolant passage during use of the heat exchanger;

an electrical insulation layer between the electrical trace and at least one of the first heat exchanger body portion and the second heat exchanger body portion, wherein the electrical insulation layer is sufficiently insulating to prevent electrical current from conducting from the electrical trace through the electrical insulation layer into at least one of the first heat exchanger body portion and the second heat exchanger body portion at 800V;

an inlet header positioned in communication with an inlet of each of the coolant passages; and

An outlet header positioned in communication with an outlet of each of the coolant passages.

2. The heat exchanger of claim 1, wherein the second body portion cooperates with only the first body portion to define a plurality of the coolant passages with the microchannels.

3. The heat exchanger of claim 1, wherein the thick film heater is printed directly onto at least one of the first body portion and the second body portion.

4. The heat exchanger of claim 1, wherein the first and second heat exchanger body portions are formed of stainless steel.

5. A coolant heater, comprising:

a first heat exchanger including a first heat exchanger body defining a plurality of first coolant passages, and a first electric heater mounted to a first face of the first heat exchanger body and including a first electrical trace for carrying a first electrical current to resistively heat coolant flowing through the first coolant passages during use of the first heat exchanger,

Wherein the first coolant passages each have an inlet and an outlet;

a first inlet header positioned in communication with an inlet of the first coolant passage and a first outlet header positioned in communication with an outlet of the first coolant passage, wherein the first electric heater extends between the first inlet header and the first outlet header; and

a controller positioned adjacent the second face of the first heat exchanger body, wherein the controller comprises a printed circuit board having a first portion with at least one high power device selected from the group of high power devices comprising microprocessors and IGBTs thereon and a second portion without any high power device thereon, wherein the printed circuit board is positioned such that the first portion of the printed circuit board is in overlapping relationship with the first inlet header and such that the second portion of the printed circuit board is in overlapping relationship with the first electric heater.

6. The coolant heater of claim 5, further comprising:

A second heat exchanger including a second heat exchanger body defining a plurality of second coolant passages, and a second electric heater mounted to a first face of the second heat exchanger body and including a second electrical trace for carrying a second electrical current to resistively heat coolant flowing through the second coolant passages during use of the second heat exchanger,

wherein the second coolant passages each have an inlet and an outlet;

wherein the first and second heat exchangers are positioned such that the first face of the first heat exchanger body faces the first face of the second heat exchanger body, such that the first and second heaters are positioned between the first and second heat exchanger bodies, and such that the second face of the first heat exchanger body faces away from the second face of the second heat exchanger body;

a second inlet header positioned in communication with the inlet of the second coolant passage and a second outlet header positioned in communication with the outlet of the second coolant passage, wherein the second electric heater extends between the second inlet header and the second outlet header.

7. The coolant heater of claim 5, further comprising a thermal conductor engaged with both the printed circuit board and the first inlet header.

8. The coolant heater of claim 5, wherein the first inlet header has an interior width and an interior height, and wherein the coolant heater further comprises a flow perturbation device positioned in the first inlet header to perturb the coolant flow in the first inlet header so as to reduce any temperature gradient in the coolant flow across a cross-sectional area of the coolant flow in the first inlet header.

9. The coolant heater of claim 5, wherein the flow perturbation device is positioned at least partially in a central portion of the inlet header, wherein the central portion of the inlet header extends across 50% of the internal width and 50% of the internal height.

10. A coolant heater, comprising:

a first heat exchanger and a second heat exchanger, wherein each of the first heat exchanger and the second heat exchanger includes a heat exchanger body defining a plurality of coolant passages, a first electric heater mounted to the heat exchanger body for resistively heating coolant flowing through the coolant passages, and a second electric heater mounted to the heat exchanger body for resistively heating coolant flowing through the coolant passages; and

A controller operatively connected in parallel to the first electric heater of each of the first and second heat exchangers, and wherein the first electric heater of the first heat exchanger is connected in parallel to the second electric heater of each of the first and second heat exchangers, and wherein the first electric heater of the second heat exchanger is connected in parallel to the second electric heater of each of the first and second heat exchangers, such that in the event of a failure of either the first electric heater or the second electric heater or either the first and second heat exchangers, the controller is operable to direct current to all remaining electric heaters of either the first or second electric heater or either the first and second heat exchangers.

11. A coolant heater, comprising:

a heat exchanger comprising a heat exchanger body defining a plurality of coolant passages and an electric heater mounted to the heat exchanger body, wherein a first electric heater comprises a first electrical trace and a second electrical trace, wherein the second electrical trace has different power consumption or different wiring than the first electrical trace,

A controller comprising a processor and a memory and connected in parallel to the first and second electrical traces, and wherein the memory contains program code executable by the processor to:

operating the controller to resistively heat coolant flowing through the coolant passage by driving current through the first electrical trace without passing current through the second electrical trace, and

the controller is operative to resistively heat coolant flowing through the coolant passage by driving current through the second electrical trace.

12. The coolant heater of claim 11, wherein the memory contains program code executable by the processor to:

the controller is operative to resistively heat coolant flowing through the coolant passage by driving current through the second electrical trace without passing current through the first electrical trace.

13. The coolant heater of claim 12, wherein the memory contains program code executable by the processor to:

The controller is operative to resistively heat coolant flowing through the coolant passage by driving current through the second electrical trace and the first electrical trace.

14. A coolant heater, comprising:

a second heat exchanger including a second heat exchanger body facing the first face of the first heat exchanger body and defining a plurality of second coolant passages, and a second electric heater mounted to the first heat exchanger body and including second electrical traces for carrying a second electrical current to resistively heat coolant flowing through the second coolant passages during use of the second heat exchanger,

A controller comprising a processor and a memory, wherein the controller is positioned adjacent to a second face of the first heat exchanger body that faces away from the first face of the first heat exchanger body.

15. The coolant heater of claim 14, wherein the second electric heater is mounted to a first face of the second heat exchanger body, wherein the first face of the second heat exchanger body faces the first face of the first heat exchanger body such that the first and second heaters are positioned between the first and second heat exchanger bodies.

16. The coolant heater of claim 15, wherein the second electrical trace is a mirror image of the first electrical trace to suppress inductance between the first and second electrical traces, wherein current flows in the second electrical trace in a direction opposite to current in the first electrical trace to cancel at least a portion of any inductance created by current in the first electrical trace.

17. The coolant heater of claim 14, wherein coolant flowing through the first coolant passage flows in parallel with coolant flowing through the second coolant passage.

18. The coolant heater of claim 14, wherein coolant flowing through the first coolant passage flows in series with coolant flowing through the second coolant passage.

19. A coolant heater, comprising:

a first heat exchanger including a first heat exchanger body defining a plurality of first coolant passages and a first electric heater mounted to the first heat exchanger body and including a first electrical trace for carrying a first electrical current to resistively heat coolant flowing through the first coolant passages during use of the first heat exchanger;

a second heat exchanger including a second heat exchanger body defining a plurality of second coolant passages and a second electric heater mounted to the second heat exchanger body and including a second electrical trace for carrying a second electrical current to resistively heat coolant flowing through the second coolant passages during use of the second heat exchanger;

A first inlet header positioned in communication with an inlet of the first coolant passage and a first outlet header positioned in communication with an outlet of the first coolant passage;

a second inlet header positioned in communication with an inlet of the second coolant passage and a second outlet header positioned in communication with an outlet of the second coolant passage;

wherein the first inlet header, the second inlet header, the first outlet header, and the second outlet header all have the same size and shape without regard to any apertures therethrough;

wherein the first inlet header is adjacent the second outlet header, and wherein the first outlet header is adjacent the second inlet header, and wherein the first outlet header has at least one first header-to-header aperture, and the second inlet header has at least one second header-to-header aperture in fluid communication with the at least one first header-to-header aperture.

20. The coolant heater of claim 19, wherein the second inlet header and the first outlet header are the same size and shape, taking into account any apertures therethrough, and differ only in orientation.

21. A coolant heater, comprising:

a heat exchanger comprising a heat exchanger body defining at least one coolant passage and an electric heater mounted to the heat exchanger body and comprising electrical traces for carrying an electrical current to resistively heat coolant flowing through the at least one coolant passage during use of the heat exchanger; and

a controller including a processor and a memory and operatively connected to the electric heater; and

a sensor for sensing a value of a characteristic of the coolant heater,

wherein the memory contains program code executable by the processor to:

pulse width modulating at least one of a current and a voltage of the electric heater to bring a value of the characteristic of the coolant heater close to a set point,

when the value of the characteristic of the coolant heater is a first amount from the set point, the pulse width modulation is performed at a first frequency, and

the pulse width modulation is performed at a second frequency higher than the first frequency when a value of the characteristic of the coolant heater is a second amount from the set point, the second amount being less than the first amount.

22. The coolant heater of claim 21, wherein the controller is programmed to adjust the pulse width modulated frequency step by step between the first frequency and the second frequency based on a gap of the value of the characteristic from the set point.

23. The coolant heater of claim 21, wherein the characteristic of the coolant heater is temperature.

24. A method for forming a heat exchanger body, comprising:

a) Providing a first body plate, a second body plate, and a third body plate positioned between the first body plate and the second body plate, wherein the third body plate includes a first end portion and a second end portion, and a plurality of dividers extending between the first end portion and the second end portion, wherein the plurality of dividers are spaced apart from one another to define coolant passages between the plurality of dividers,

wherein the first end portion, a first end section of the divider immediately adjacent to the first end portion, the second end portion, and a second end section of the divider immediately adjacent to the second end portion are positioned outside of the first and second body panels, and wherein a cover portion of the divider is sandwiched between the first and second body panels;

b) Joining a plurality of the spacers to the first body plate and the second body plate; and

25. The method of claim 24, wherein step b) includes brazing a plurality of the spacers individually to the first and second body plates.

26. The method of claim 24, wherein the divider is a rectangular bar.

27. A method for forming a heat exchanger, comprising:

a) Forming a heat exchanger body by the method of claim 24;

c) An outlet header is provided and mounted to the heat exchanger body in fluid communication with at least some of the coolant passages.

28. The method of claim 24, further comprising applying an electric heater to one of the first body plate and the second body plate.

29. A coolant heater, comprising:

a first heat exchanger comprising a first heat exchanger body defining a plurality of first coolant passages, and a first electric heater mounted to the first heat exchanger body and comprising a first electrical trace for resistively heating coolant flowing through the first coolant passages during use of the first heat exchanger;

a second heat exchanger comprising a second heat exchanger body defining a plurality of second coolant passages, and a second electric heater mounted to the second heat exchanger body and comprising second electrical traces for resistively heating coolant flowing through the second coolant passages during use of the second heat exchanger;

a first switching device;

a second switching device;

a first electrical conduit electrically connecting the first switching device to the first electric heater such that the first switching device is electrically upstream of the first electric heater;

A second electrical conduit electrically connecting the second switching device to the second electric heater such that the second switching device is electrically upstream of the second electric heater;

a third switching device;

a fourth switching device;

a third electrical conduit electrically connecting the first electric heater to the third switching device such that the third switching device is electrically downstream of the first electric heater;

a fourth electrical conduit electrically connecting the second electric heater to the fourth switching device such that the fourth switching device is electrically downstream of the second electric heater;

a fifth electrical conduit connecting the first and second electrical conduits to each other downstream of the first and second switching devices so as to electrically connect the first switching device to the second electric heater and the second switching device to the first electric heater;

a controller comprising a processor and a memory, wherein the processor is operatively connected to the first switching device, the second switching device, the third switching device, and the fourth switching device;

Wherein in a first mode of operation of the coolant heater, the third and fourth switching devices are fully closed and the first and second switching devices are operative to pulse width modulation control the current passing through the first and second electric heaters, respectively,

wherein in the event of an open fault of the first switching device while in the first mode of operation, current from the second switching device is transferred to the second electric heater through the second electrical conduit and to the first electric heater through the fifth electrical conduit while the third switching device and the fourth switching device remain fully closed to operate the coolant heater in a second mode of operation, and

wherein in the event of a closure failure of the first switching device while in the first mode of operation, the processor is programmed to initiate operation of the third switching device and the fourth switching device, to the first electric heater via the fifth electrical conduit, to operate the coolant heater in a third mode of operation.

30. The coolant heater of claim 29, wherein in the third mode of operation, the second switching device is held closed by the processor.