Coolant-refrigerant heat exchanger and thermal management system

Abstract

In an aspect, a coolant-refrigerant heat exchanger for a thermal management system for an electric vehicle is provided, and includes a coolant flow path for transporting coolant therethrough, a refrigerant flow path for transporting refrigerant therethrough, wherein the coolant flow path and the refrigerant flow path are positioned in order to transfer heat from one of the coolant and the refrigerant to the other. A flow plate subassembly is provided and includes a plurality of flow plates joined together. A heat transfer plate and a form-fitting heat transfer material positioned in the spaces between the heat transfer plate and the flow plate subassembly. The heat transfer material joins the heat transfer plate to the flow plate subassembly. A secondary heater is energizable to heat the refrigerant and coolant in the heat exchanger by heat conduction through the heat transfer plate, the heat transfer material and the flow plates.

Description

COOLANT-REFRIGERANT HEAT EXCHANGER AND THERMAL MANAGEMENT SYSTEMCROSS-REFERENCES TO RELATED APPLICATIONS

[0001] This application relates to a coolant-refrigerant heat exchanger and a thermal management system shown and described in US provisional patent application 63 / 496,451 , filed April 17, 2023, and US provisional patent application 63 / 463,471 , filed May 2, 2023, the contents of both of which are incorporated herein by reference in their entirety.FIELD OF THE DISCLOSURE

[0002] This disclosure relates generally to the field of heat exchangers and more particularly to a coolant-refrigerant heat exchanger and associated thermal management system for use in an electric vehicle.BACKGROUND

[0003] Thermal management systems in electric vehicles (EVs) are known to employ coolant heaters for the purpose of heating coolant that is ultimately circulated through components of the EV that require heating for performance reasons, such as the vehicle’s battery. Additionally, refrigerant heaters are known in EV’s for serving certain specific purposes. However, each of the existing thermal management systems suffers from certain deficiencies. It is of continued interest to improve the performance and efficiency of EV thermal management systems.SUMMARY

[0004] In an aspect, the disclosure relates to a coolant-refrigerant heat exchanger for a thermal management system for an electric vehicle, comprising: a coolant flow path for transporting coolant therethrough, a refrigerant flow path for transporting refrigerant therethrough, wherein the coolant flow path and the refrigerant flow path are positioned in order to transfer heat from one of the coolant and the refrigerant to the other of the coolant and the refrigerant, wherein the coolant-refrigerant heat exchanger includes a flow plate subassembly that includes a plurality of flow plates joined together, wherein the plurality of flow plates together define the coolant flow path and the refrigerant flow path, each of the plurality of flow plates having a plurality of faces and a peripheral edge, the flow plate subassembly having a peripheral edge that is made up of the peripheral edges of the flow plates, wherein there are a plurality of spaces between the plurality of flow plates at the peripheral edge of the flow plate subassembly; a heat transfer plate having a first heat transfer plate face that faces the flow plate subassembly and a second heat transfer plate face that is opposite the first heat transfer plate face; a form-fitting heat transfer material positioned in the spaces, wherein the form-fitting heat transfer material is thermally conductive, and joins the heat transfer plate to the peripheral edge of the flow plate subassembly; and a secondary heater that is positioned on the second heat transfer plate face, wherein the secondary heater is energizable to heat both the refrigerant and the coolant in the coolant-refrigerant heat exchanger by heat conduction through the heat transfer plate, the formfitting heat transfer material and the flow plates.BRIEF DESCRIPTION OF THE DRAWINGS

[0005] The foregoing and other aspects of the invention will be better appreciated with reference to the attached drawings, as follows:

[0006] Figure 1 is a schematic view of a basic vehicular air conditioning system using refrigerant, in accordance with the prior art.

[0007] Figure 2 is a pressure-enthalpy chart for the refrigerant in the air conditioning system shown in Figure 1 .

[0008] Figure 3A is a schematic view of a basic vehicular heat pump system, in accordance with the prior art, in a cooling mode.

[0009] Figure 3B is a schematic view of the heat pump system shown in Figure 3A, in a heating mode.

[0010] Figure 4 is a pressure-enthalpy chart for the refrigerant in the air conditioning system shown in Figure 1 .

[0011] Figure 5 is a schematic view of a vehicular thermal management system that incorporates a coolant system and a refrigerant system, in accordance with an embodiment of the present disclosure.

[0012] Figure 6 is a perspective view of a coolant-refrigerant heat exchanger, in accordance with an embodiment of the present disclosure, which includes a secondary heater.

[0013] Figures 7a and 7b together are a perspective exploded view of the coolant-refrigerant heat exchanger shown in Figure 6.

[0014] Figure 8 is a magnified perspective view of a portion of the coolantrefrigerant heat exchanger shown in Figure 6.

[0015] Figure 9 is a perspective sectional view of the coolant-refrigerant heat exchanger shown in Figure 6.

[0016] Figure 10 is a perspective, partially-exploded view of a portion of the coolant-refrigerant heat exchanger shown in Figure 10, illustrating the flow of coolant and refrigerant therethrough.

[0017] Figure 11 is a schematic illustration showing the flow of coolant and refrigerant through the coolant-refrigerant heat exchanger shown in Figure 6.

[0018] Figure 12 is a schematic illustration showing an alternative flow path for coolant and refrigerant through an alternative embodiment of the coolant-refrigerant heat exchanger shown in Figure 6.

[0019] Figure 13 is a schematic illustration of a thermal management system in accordance with an embodiment of the present disclosure, incorporating the coolantrefrigerant heat exchanger shown in Figure 6, in a cabin heating mode using the secondary heater.

[0020] Figure 14 is a side elevation view of an electric vehicle incorporating the thermal management system shown in Figure 13.

[0021] Figure 15 is a perspective view of another embodiment of the coolantrefrigerant heat exchanger in which a secondary heater is employed, along with a heat transfer plate.

[0022] Figure 16A is a magnified sectional view of a portion of the embodiment shown in Figure 15.

[0023] Figure 16B is a further magnified sectional view of a portion of the embodiment shown in Figure 15.

[0024] Figure 17 is an exploded view of the embodiment shown in Figure 15.

[0025] Figure 18 is a sectional view of the embodiment shown in Figure 15, including an optional mechanical holding member.

[0026] Figure 19A is a sectional view of another embodiment of the coolantrefrigerant heat exchanger in which a plurality of cartridge heaters are employed.

[0027] Figure 19B is a perspective view of a flow plate for use with the embodiment shown in Figure 19A.

[0028] Figure 19C is another sectional view of a variant of the coolant-refrigerant heat exchanger shown in Figure 19A.

[0029] Figure 19D is a magnified view of a portion of the view shown in Figure19C.

[0030] Figure 19E is a side view of a cartridge heater for use with the embodiments shown in Figures 19A and 19C.

[0031] Figure 19E is a sectional side view of another cartridge heater for use with the embodiments shown in Figures 19A and 19C.

[0032] Figure 19E is a sectional side view of yet another cartridge heater for use with the embodiments shown in Figures 19A and 19C.

[0033] Figure 19H is a sectional side view of yet another cartridge heater for use with the embodiments shown in Figures 19A and 19C.

[0034] Figure 20A is a sectional view of another embodiment of the coolantrefrigerant heat exchanger, also employing a particulate material to transfer heat from the thick film heater to the flow plates of the coolant-refrigerant heat exchanger.

[0035] Figure 20B is a magnified sectional view of the embodiment shown in Figure 20A.

[0036] Figure 21A is a sectional side view of yet another embodiment of the coolant-refrigerant heat exchanger, in which a die-cast material is employed.

[0037] Figure 21 B is a magnified sectional view of the embodiment shown in Figure 21A.DETAILED DESCRIPTION OF EXAMPLE EMBODIMENTS

[0038] For simplicity and clarity of illustration, where considered appropriate, reference numerals may be repeated among the Figures to indicate corresponding or analogous elements. In addition, numerous specific details are set forth in order to provide a thorough understanding of the embodiment or embodiments described herein. However, it will be understood by those of ordinary skill in the art that the embodimentsdescribed 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 figures and described below, the principles of the present disclosure may be implemented using any number of techniques, whether currently known or not. The present disclosure should in no way be limited to the exemplary implementations and techniques illustrated in the drawings and described below.

[0039] Various terms used throughout the present description may be read and understood as follows, unless the context indicates otherwise: “or” as used throughout is inclusive, as though written “and / or”; singular articles and pronouns as used throughout include their plural forms, and vice versa; similarly, gendered pronouns include their counterpart pronouns so that pronouns should not be understood as limiting anything described herein to use, implementation, performance, etc. by a single gender; “exemplary” should be understood as “illustrative” or “exemplifying” and not necessarily as “preferred” over other embodiments. Further definitions for terms may be set out herein; these may apply to prior and subsequent instances of those terms, as will be understood from a reading of the present description.

[0040] Modifications, additions, or omissions may be made to the systems, apparatuses, and methods described herein without departing from the scope of the disclosure. For example, the components of the systems and apparatuses may be integrated or separated. Moreover, the operations of the systems and apparatuses disclosed herein may be performed by more, fewer, or other components and the methods described may include more, fewer, or other steps. Additionally, steps may be performed in any suitable order. As used in this document, “each” refers to each member of a set or each member of a subset of a set.

[0041] The indefinite article “a” is not intended to be limited to mean “one” of an element. It is intended to mean “one or more” of an element, where applicable, (i.e. unless in the context it would be obvious that only one of the element would be suitable).

[0042] Any reference to upper, lower, top, bottom or the like are intended to refer to an orientation of a particular element during use of the claimed subject matter and not necessarily to its orientation during shipping or manufacture. The upper surface of an element, for example, can still be considered its upper surface even when the element is lying on its side.

[0043] DESCRIPTION OF BASIC AIR CONDITIONING SYSTEM

[0044] Reference is made to Figure 1 , which shows schematic diagram of a typical vehicular air conditioning system 10, in accordance with the prior art. It will be noted that the air conditioning system 10 shown in Figure 1 has been simplified in the sense that several components that are typically present, have been omitted here for simplicity.

[0045] The air conditioning system 10 shown in Figure 1 circulates a refrigerant through various components in order to cool a vehicle’s passenger cabin (shown schematically at 12). The air conditioning system 10 employs a compressor 14, a condenser 16, an expansion valve 18, and an evaporator 20.

[0046] The refrigerant enters the compressor 14 at a relatively low pressure, such as, for example, about 140 kPa, and a relatively low temperature such as, for example, - 25 degrees Celsius. The compressor 14 compresses the refrigerant, to bring the refrigerant to a high pressure, such as, for example, about 1200 kPa. The compression of the refrigerant raises its temperature to, for example, about 110 degrees Celsius. As a result, the refrigerant is a high pressure, high temperature gas when leaving the compressor. The refrigerant then passes to the condenser 16. The condenser 16 is used to condense the refrigerant, by carrying out heat transfer from the refrigerant flowing therethrough to the air that surrounds the condenser 16. The condenser 16 is positioned outside the passenger cabin 12, such as in the engine compartment, shown at 21 , in embodiments in which the vehicle includes an engine. As a result of its placement, the condenser 16 is exposed to outside air, shown at 22, (which is air from outside the passenger cabin 12), as distinguished from interior air, shown at 24, (which is air from inside the passenger cabin 12). An outside fan 26 is provided to enhance theflow of the outside air 22 over the condenser 16. The temperature of the outside air 22 is lower than that of the refrigerant, and so the refrigerant condenses in the condenser 16, and leaves the condenser 16 as a liquid.

[0047] The refrigerant then passes through the expansion valve 18, so as to reduce the pressure of the refrigerant. Some of the refrigerant may evaporate due to the reduction in pressure, however, a significant portion of the refrigerant remains liquid. The reduction in pressure of the refrigerant cools the refrigerant. Thus, the refrigerant leaves the expansion valve 18 as a low pressure, low temperature liquid or liquid / gas mix. The refrigerant then passes through the evaporator 20, which transfers heat from the interior air 24 to the refrigerant, in order to raise the temperature of the refrigerant so as to drive the evaporation of the refrigerant. An interior fan 28 may be provided to encourage the flow of interior air 24 over the evaporator 20. The evaporator 20 is positioned inside the passenger cabin 12 in the sense that the evaporator 20 may be positioned aft of the firewall in the vehicle, which separates the engine compartment 21 from the passenger cabin 12, and, more importantly, is exposed to a flow of the interior air 24. For greater clarity, the interior air 24 is air that is directed into the passenger cabin 12. Raising the temperature of the refrigerant in the evaporator 20 correspondingly cools the interior air 24, thereby cooling the interior air 24.

[0048] The refrigerant then leaves the evaporator 20 and returns to the inlet of the compressor 14, where it is compressed again and sent again to the condenser 16 in a continuous cycle.

[0049] DESCRIPTION OF BASIC PRESSURE-ENTHALPY CHART

[0050] Figure 2 is a pressure-enthalpy chart that shows the refrigeration cycle that the refrigerant undergoes, in a graphical format. As will be understood by one skilled in the art, the inverted U-shaped line represents the gas / liquid transition properties for the refrigerant. The dot-dash curve shown at 30 represents the changes in the properties of the refrigerant as it passes through the refrigeration cycle shown in Figure 1. Point 32 represents the properties of the refrigerant immediately upstream of the compressor 14. Curve segment 30a is representative of the change in theproperties of the refrigerant due to operation of the compressor 14. Point 34 is representative of the properties of the refrigerant downstream of the compressor 14 and upstream from the condenser 16. As can be seen, the pressure and the temperature of the refrigerant increase between point 32 and point 34.

[0051] Curve segment 30b is representative of the change in the properties of the refrigerant due to operation of the condenser 16. Point 36 is representative of the properties of the refrigerant immediately downstream of the condenser 16 (and therefore upstream from the expansion valve 18). As can be seen, the temperature of the refrigerant decreases and then remains constant during the phase change that occurs in the condenser 16..

[0052] Curve segment 30c is representative of the change in the properties of the refrigerant due to the expansion valve 18. Point 38 is representative of the properties of the refrigerant immediately downstream of the expansion valve 18 and therefore upstream from the evaporator 20). As can be seen, the pressure and temperature of the refrigerant decrease as a result of passing through the expansion valve.

[0053] Curve segment 30d is representative of the change in the properties of the refrigerant due to passage through the evaporator 20. After passing through the evaporator 20, the refrigerant returns to point 32, which is representative of the properties of the refrigerant immediately downstream of the evaporator 20 (and therefore of the properties of the refrigerant immediately upstream of the compressor 14). As can be seen, the pressure and the temperature remain substantially constant in the evaporator 20. This is because the heat being transferred to the refrigerant is being used to drive the phase change (i.e. the evaporation) of the refrigerant, which occurs at a constant temperature, as will be understood by one skilled in the art. Optionally, the evaporator 20 may be sized to transfer to the refrigerant a bit more than the minimum amount of heat that is needed to evaporate all of the refrigerant, so as to drive an increase in temperature of the refrigerant once all of it has evaporated. This ensures that all of the refrigerant leaves the evaporator as a gas, with no fraction thereof remaining as a liquid. It is advantageous for all of the refrigerant to be in gaseous formwhen reaching the inlet of the compressor 14 so as to avoid damaging the compressor 14.

[0054] DESCRIPTION OF BASIC HEAT PUMP SYSTEM

[0055] Figures 3A and 3B show a thermal management system that is more sophisticated than the air conditioning system shown in Figure 1. The thermal management system may be referred to as a heat pump system and is shown at 40. The heat pump system 40 is similar to the air conditioning system 10 and includes the compressor 14 and the expansion valve 18, but also includes some different components. For example, the heat pump system 40 includes an outside heat exchanger 42 and an interior heat exchanger 44 instead of the condenser 16 and evaporator 20 shown in Figure 1 , respectively. The heat pump system 40 further includes a reversing valve 46, which is explained further below. The heat pump system 40 is capable of cooling the passenger cabin 12 in similar manner to the air conditioning system 10, but is also capable of heating the passenger cabin 12, using little extra equipment.

[0056] The outside heat exchanger 42 may be similar to the condenser 16 in the sense that the outside heat exchanger 42 is usable to carry out heat transfer from the refrigerant flowing therethrough to the air that surrounds the outside heat exchanger 42, in order to condense the refrigerant, but is also capable of receiving a flow of refrigerant liquid in the opposite direction therethrough in order to carry out heat transfer thereto from the air that surrounds the outside heat exchanger 42, in order to evaporate the refrigerant.

[0057] The interior heat exchanger 44 may be similar to the evaporator 20 in the sense that the interior heat exchanger 44 is inside the passenger cabin 12 and is usable to carry out heat transfer to the refrigerant flowing therethrough from the air that surrounds the interior heat exchanger 44, in order to evaporate the refrigerant, but is also capable of receiving a flow of refrigerant gas in the opposite direction therethrough in order to carry out heat transfer from the refrigerant to the air that surrounds the interior heat exchanger 44, in order to condense the refrigerant.

[0058] The reversing valve 46 is positionable in a plurality of positions, including a first position (Figure 3A) in which the reversing valve 46 transfers refrigerant flow from the compressor 14 to the outside heat exchanger 42 and from the interior heat exchanger 44 to the compressor 14, and a second position in which the reversing valve 46 transfers refrigerant flow to the interior heat exchanger 44 from the compressor 14 and to the compressor 14 from the outside heat exchanger 42.

[0059] The heat pump system 40 is operable in a first mode (Figure 3A), in which the reversing valve 46 is in the first position, used for cooling the passenger cabin 12, and a second mode (Figure 3B), in which the reversing valve 46 is in the second position, used for heating the passenger cabin 12.

[0060] The first mode (Figure 3A) is described as follows: The refrigerant enters the compressor 12 at a relatively low pressure, and a relatively low temperature. The compressor 12 compresses the refrigerant, to bring the refrigerant to a high pressure, which raises its temperature. As a result, the refrigerant is a high pressure, high temperature gas when leaving the compressor. The refrigerant then passes to the outside heat exchanger 42. The outside heat exchanger 42 acts as a condenser and is used to condense the refrigerant, by carrying out heat transfer from the refrigerant flowing therethrough to the outside air 22 that surrounds the outside heat exchanger 42. Optionally the outside fan 26 is provided to enhance air flow across the outside heat exchanger 42, and therefore enhances heat transfer from the outside heat exchanger 42. The refrigerant then passes through the expansion valve 18, so as to reduce the pressure of the refrigerant. Some of the refrigerant may evaporate due to the reduction in pressure, however, a significant portion of the refrigerant remains liquid. The reduction in pressure of the refrigerant cools the refrigerant. Thus, the refrigerant leaves the expansion valve 18 as a low pressure, low temperature liquid or liquid / gas mix. The refrigerant then passes through the interior heat exchanger 44, which acts as an evaporator and which transfers heat from the interior air 24 to the refrigerant (thereby cooling the interior air 24), in order to raise the temperature of the refrigerant so as to drive the evaporation of the refrigerant. Optionally the interior fan 28 is provided and is used to enhance air flow across the interior heat exchanger 44, and therefore enhancesheat transfer from the interior air 24 to the refrigerant. The cooled interior air 24 cools the passenger cabin 12. The refrigerant then passes to the inlet of the compressor 14, where it is compressed again and sent again to the reversing valve 46 in a continuous cycle.

[0061] The second mode (Figure 3B) is described as follows: The refrigerant enters the compressor 12 at a relatively low pressure, and a relatively low temperature. The compressor 12 compresses the refrigerant, to bring the refrigerant to a high pressure, which raises its temperature. As a result, the refrigerant is a high pressure, high temperature gas when leaving the compressor 14. The refrigerant then passes to the interior heat exchanger 44, which acts as a condenser and is used to condense the refrigerant, by carrying out heat transfer from the refrigerant flowing therethrough to the interior air 24 that surrounds the interior heat exchanger 44 (thereby heating the interior air 24). Optionally the interior fan 28 is provided to enhance air flow across the interior heat exchanger 44, and therefore enhances heat transfer from the refrigerant to the interior air 24. The heated interior air 24 heats the passenger cabin 12. The refrigerant then passes through the expansion valve 18, so as to reduce the pressure of the refrigerant. Some of the refrigerant may evaporate due to the reduction in pressure, however, a significant portion of the refrigerant remains liquid. The reduction in pressure of the refrigerant cools the refrigerant. Thus, the refrigerant leaves the expansion valve 18 as a low pressure, low temperature liquid or liquid / gas mix. The refrigerant then passes through the outside heat exchanger 42, which acts as an evaporator and which transfers heat from the outside air 22 to the refrigerant, in order to raise the temperature of the refrigerant so as to drive the evaporation of the refrigerant. Optionally the outside fan 28 is provided and is used to enhance air flow across the outside heat exchanger 42, and therefore enhances heat transfer from the outside air 22. The refrigerant then passes to the inlet of the compressor 14, where it is compressed again and sent again to the reversing valve 46 in a continuous cycle.

[0062] Thus, by moving the reversing valve 46 between the first and second positions, the heat pump system 40 can be used to either heat or cool the passenger cabin, as desired.

[0063] Figure 4 is a pressure-enthalpy diagram illustrating the property changes that the refrigerant undergoes during operation of the heat pump system 40 shown in Figures 3A and 3B. As can be seen the general shape of the curve 30 in Figure 4 is similar to the shape of the curve 30 in Figure 2.

[0064] It will be noted that in a heat pump system such as the heat pump system 40, the refrigerant properties undergo the same cycle of compression, condensation, reduction in pressure, and evaporation, regardless of whether the heat pump system 40 is operating in the first mode or the second mode. Referring to Figure 4, point 32 corresponds to the properties of the refrigerant immediately upstream of the compressor, as before. Point 34 corresponds to the properties of the refrigerant downstream from the compressor 14 and upstream from the outside heat exchanger 42 when operating in the first mode, and downstream from the compressor and upstream from the interior heat exchanger 44 when operating in the second mode. Point 36 corresponds to the properties of the refrigerant downstream from the outside heat exchanger 42 and upstream from the expansion valve 18 when operating in the first mode, and downstream from the interior heat exchanger 44 and upstream from the expansion valve 18 when operating in the second mode. Point 38 corresponds to the properties of the refrigerant downstream from the expansion valve 18 and upstream from the interior heat exchanger 44 when operating in the first mode, and downstream from the expansion valve 18 and upstream from the outside heat exchanger 42 when operating in the second mode.

[0065] DESCRIPTION OF THERMAL MANAGEMENT SYSTEM WITHCOOLANT-REFRIGERANT HEAT EXCHANGER

[0066] Figure 5 shows a thermal management system 50 that is more sophisticated than the heat pump system 40 shown in Figures 3A and 3B. The thermal management system 50 shown in Figure 5 includes a refrigerant system 52 and a coolant system 54. In Figure 5, a solid line represents a coolant conduit, and a dashed line represents a refrigerant conduit. The refrigerant system 52 includes a compressor 56, a plurality of control valves shown at V1 , V2, V3, and V4, a plurality of refrigerant check valves shown at CV1 , CV2, CV3 and CV4, a plurality of expansion valves shownat EXV1 , EXV2, and EXV3, an outside heat exchanger 58, an interior evaporator 60, and an interior condenser 62. The control valves V1 , V2, V3 and V4 may be simple on- off valves (e.g. solenoid valves). The outside heat exchanger 58 may be similar to the outside heat exchanger 16 shown in Figures 3A and 3B. The evaporator 60 and the interior condenser 62 may be provided instead of the interior heat exchanger 20 of Figures 3A and 3B, in order to enable enhanced functionality (e.g. both heating and defogging simultaneously), or for other reasons.

[0067] The coolant system 54 includes a first pump 64, a second pump 66, a plurality of control valves shown at 68a and 68b, a coolant check valve shown at 70, a high voltage heater 71 , and a radiator 72. Thermal loads may be present. In the case where the vehicle is an EV, the thermal loads may include, for example, a traction battery 74, and a traction motor 76 (including associated power electronics). A coolantrefrigerant heat exchanger 78 is provided, for heat exchange between the coolant in the coolant system 54 and the refrigerant in the refrigerant system 52. The coolantrefrigerant heat exchanger 78 has a coolant flow path 78a therethrough, and a refrigerant flow path 78b therethrough.

[0068] The operation of the thermal management system 50 is described as follows: The refrigerant system 52 is operable in a greater number of modes than the heat pump system 40 shown in Figures 3A and 3B. Such modes include a first mode, to heat the passenger cabin 12 using heat from the coolant in the coolant system 54 via the coolant-refrigerant heat exchanger 78, a second mode, to heat the passenger cabin 12 using heat from the coolant in the coolant system 54, and also using the outside heat exchanger 58 as an evaporator, and a third mode, to cool the passenger cabin 12, using the outside heat exchanger 58 as a condenser.

[0069] In the first mode, the control valves V1 , V2, V3 and V4 are controlled so as to direct refrigerant flow from the compressor 56, through the control valve V2, and through the interior condenser 62, where the refrigerant condenses and transfers heat to the interior air shown at 24, in order to heat the passenger cabin 12. From the interior condenser 62, the refrigerant passes through the check valve CV1. Downstream from the check valve CV1 , the refrigerant flow may be directed through afirst refrigerant flow path 80a through an optional refrigerant-refrigerant heat exchanger 80, through the expansion valve EXV3, through the coolant-refrigerant heat exchanger 78, back through a second refrigerant flow path 80b through the refrigerant-refrigerant heat exchanger 80, and back to the inlet of the compressor 56. In the refrigerantrefrigerant heat exchanger 80, some heat is scavenged from the refrigerant in the first refrigerant flow path 80a to add heat to the refrigerant in the second refrigerant flow path 80b so as to further superheat the refrigerant in the second refrigerant flow path 80b to reduce the chance of any liquid refrigerant being present in that flow that could damage the compressor 56 that is downstream from it.

[0070] In the coolant-refrigerant heat exchanger 78, the refrigerant receives heat from the coolant flowing therethrough, thereby driving evaporation of the refrigerant, which is at low pressure as a result of passing through the third expansion valve EXV3. The coolant may be heated by one or more of several sources. This includes the traction battery 74, and / or the traction motor 76 (and the associated power electronics), and / or the high voltage heater 71. More specifically, during discharging, and during charging, of the traction battery 74, heat is generated, which is transmitted to the coolant. Additionally the traction motor 76 and the associated power electronics generate heat during operation of the traction motor 76. In some situations however, such as upon vehicle startup when it is very cold outside, the traction battery 74 and the traction motor 76 may not be warm enough to provide sufficient heat to the coolant for heating the refrigerant in the coolant-refrigerant heat exchanger 78. In such situations, the high voltage heater 71 may be operated to heat the coolant, in order to heat the refrigerant in the coolant-refrigerant heat exchanger 78 sufficiently to evaporate the refrigerant. The refrigerant then passes from the coolant-refrigerant heat exchanger 78 to the second refrigerant flow path 80b in the refrigerant-refrigerant heat exchanger 80, and from there to the inlet of the compressor 56.

[0071] Optionally, a receiver / dryer 97 is provided to remove contaminants from the refrigerant, such as oils, water, dirt and debris as these contaminants can damage components such as the compressor 56.

[0072] In the first mode described above, all of the refrigerant flow passes through the coolant-refrigerant heat exchanger 78. In the second mode of operation, only a first portion of the refrigerant passes through the coolant-refrigerant heat exchanger 78 as described above, and a second portion of the refrigerant passes to the first expansion valve EXV1 , where its pressure will be reduced. From there, the second portion of the refrigerant travels to the outside heat exchanger 58, which will act as an evaporator, in order to evaporate the second portion of the refrigerant. The evaporated refrigerant passes from the outside heat exchanger 58 through the control valve V3, through the check valve CV3, and through the second refrigerant flow path 80b in the refrigerant-refrigerant heat exchanger 80 along with the first portion of the refrigerant, and from there to the inlet of the compressor 56.

[0073] In the third mode of operation for the thermal management system 50, the control valves V1 , V2, V3 and V4 are controlled so as to direct refrigerant flow from the compressor 56, through the control valve V1 , through the outside heat exchanger 58, which acts as a condenser, through the check valve CV2, through the first refrigerant flow path 80a through the refrigerant-refrigerant heat exchanger 80, through the second expansion valve EXV2, where the pressure of the refrigerant is reduced, and then through the interior evaporator 60 where the refrigerant is evaporated, thereby cooling the interior air 24, so as to cool the passenger cabin 12. From the interior evaporator 60, the refrigerant passes through the second refrigerant flow path 80b of the refrigerant-refrigerant heat exchanger 80, and from there to the inlet of the compressor 56.

[0074] The thermal management system 50 is advantageous over the heat pump system 40 shown in Figures 3A and 3B, in that the coolant-refrigerant heat exchanger 78 permits heat from the coolant to be used to help heat the refrigerant in situations where such heat is available and / or beneficial.

[0075] DESCRIPTION OF STRUCTURE OF NOVEL COOLANT-REFRIGERANT HEAT EXCHANGER

[0076] Reference is made to Figures 6-10, which show a coolant-refrigerant heat exchanger 100 in accordance with an embodiment of the present disclosure. Figure 6 is a perspective view of the coolant-refrigerant heat exchanger 100. Figures 7a and 7b together are a perspective exploded view of the coolant-refrigerant heat exchanger 100. Figure 8 is a magnified perspective view of a portion of the coolant-refrigerant heat exchanger 100. Figure 9 is a sectional view of the coolant-refrigerant heat exchanger 100, and Figure 10 is a partially exploded perspective view of a portion of the coolantrefrigerant heat exchanger 100.

[0077] The coolant-refrigerant heat exchanger 100 may be for use in an electric vehicle 151 shown in Figure 14. The electric vehicle 151 may include the passenger cabin 12, the traction battery 74, and the traction motor 76 (for driving one or more of the wheels shown at 99). The electric vehicle 151 may be any type of vehicle that employs a traction motor and a traction battery for supplying power to the traction motor. The electric vehicle 151 is shown as sedan, but it could be an SUV, a light-duty truck, a heavy-duty truck, an off-road vehicle, a vehicle used in construction, an aircraft, or any other suitable type of vehicle. Furthermore, the electric vehicle 151 may contain only a traction motor (or several of them) for driving movement of the electric vehicle 151 , or alternatively, it may contain an internal combustion engine, such as a range extender engine to assist in recharging the traction battery 74 when the traction battery 74 at or near depletion. In yet other embodiments, the electric vehicle 151 may be a fuel-cell vehicle, generating electric power via a fuel cell, for powering the traction motor 76.

[0078] It will be noted that the traction battery 74 shown in the figures is just one example of an energy source for the electric vehicle 151 . In embodiments in which the electric vehicle 151 is a fuel-cell vehicle, the electric vehicle 151 includes a fuel-cell stack and may also include a traction battery (albeit a smaller one than in a typical battery-electric vehicle). The fuel-cell stack and the traction battery (if one is provided) would constitute an energy source for the fuel-cell vehicle. In the embodiments shown herein, the energy source is a traction battery that is connected to the traction motor to provide electrical power to the traction motor.

[0079] The electric vehicle 151 may further include a thermal management system 150, which is described in more detail further below in relation to Figure 13. The thermal management system 150 may include the coolant-refrigerant heat exchanger 100.

[0080] The coolant-refrigerant heat exchanger 100 includes a coolant flow path 102 (Figure 10) for transporting coolant (represented by arrows 104 in Figure 10) therethrough, and a refrigerant flow path 106 (Figures 10 and 11 ) for transporting refrigerant (represented by arrows 108 in Figure 10) therethrough. The coolant flow path 102 and the refrigerant flow path 106 are positioned so as to transfer heat from one of the coolant 104 and the refrigerant 108 to the other of the coolant 104 and the refrigerant 108. In the example, shown, the coolant-refrigerant heat exchanger 100 includes a plurality of flow plates 110. Each flow plate 110 has a first face 112a and a second face 112b shown in Figures 7b and 9, and a peripheral edge 114 (Figure 7b). The plurality of flow plates 110 are connected together such that the coolant flow path 102 and the refrigerant flow path 106 are defined between mutually facing ones of the faces of adjacent ones of the plurality of flow plates 110. More specifically, with reference to Figures 9 and 10, in the embodiment shown, the coolant flow path 102 is defined between the second face 112b of the first plate (shown at 110a) and the first face 112a of the second plate (shown at 110b), between the second face 112b of a third plate (shown at 110c) and the first face 112a of a fourth plate (shown at 110d), between the second face 112b of a fifth plate (shown at 110e) and the first face 112a of a sixth plate (shown at 11 Of), and so on. Analogously, the refrigerant flow path 106 is defined between the first face 112a of the second flow plate 110b and the second face 112b of the third flow plate 110c, between the first face 112a of the fourth plate (shown at 110d) and the second face 112b of the fifth flow plate 110e, and so on. In the embodiment shown, there are 32 flow plates 110 which are sealingly joined together to form a flow plate subassembly 117. It will be understood that any suitable number of flow plates 110 may be used, depending on specific parameters of the application in which the coolant-refrigerant heat exchanger 100 is to be used.

[0081] The flow plates 110 may be made from any suitable material, such as, for example, aluminum. While it is known that aluminum has a higher thermal conductivity than certain materials such as stainless steel, aluminum is not the typical material used for coolant or refrigerant conduits in coolant-refrigerant heat exchangers in vehicles.

[0082] As can be seen in Figure 7A, the peripheral edge 114 of the flow plates 110 is rectangular with rounded comers (a rounded rectangle) in the embodiment shown. However, it will be understood that the peripheral edge 114 could have any other suitable shape, such as a circular shape, an elliptical shape, a regular or irregular polygonal shape with rounded corners having more or fewer than 4 sides or any other suitable shape. The shape of the peripheral edge 114 preferably has rounded corners where comers are present, however, comers that have substantially no rounding may be provided instead.

[0083] With reference to Figure 7a, in the embodiment shown, a first end cover plate 109 is sealingly joined to a first end of the plurality of flow plates 110 and includes a refrigerant inlet 116a, a refrigerant outlet 116b, a coolant inlet 118a and a coolant outlet 118b. The first end cover plate 109 may be joined to the flow plates 110 in the same way that the flow plates 110 are joined to one another, and may be processed along with the flow plates to further form the heat exchange surface 242. A refrigerant filter 119 may be provided at the refrigerant inlet 116a to filter contaminants from the refrigerant 108 before it passes through the flow plates 110.

[0084] A second end cover plate 111 (Figure 9) is sealingly joined to a second end of the plurality of flow plates 110. The second end cover plate 111 may be joined to the flow plates 110 in the same way that the flow plates 110 are joined to one another, and may be processed along with the flow plates to further form the heat exchange surface 242.

[0085] With reference to Figures 7b and 8, each of the flow plates 110 has a plurality of ridges 120 thereon on each of the first and second faces 112a and 112b, which define grooves which act as channels for the flow of refrigerant 108 or coolant 104 as the case may be. In the embodiment shown, the ridges 120 on each flow plate110 form a pattern that alternates with the pattern of the ridges 120 on each adjacent flow plate 110. In other words, the ridges on the odd-numbered flow plates 110, (i.e., the first plate, the third plate, the fifth plate, etc.), form a pattern that alternates with the pattern on the even-numbered flow plates 110, (i.e. the second plate, the fourth plate, the sixth plate, etc.). The patterns of the ridges 120 on both the odd-numbered flow plates 110 and the even-numbered flow plates 110 may be herringbone patterns.

[0086] Figure 9 shows a sectional view of the coolant-refrigerant heat exchanger 100. As can be seen, the flow plates 110 have first and second refrigerant pass- through apertures 113 and first and second coolant pass-through apertures 115. The space between the first flow plate 110a and the second flow plate 110b is a first coolant space 121 . The space between the second flow plate 110b and the third flow plate 110c is a first refrigerant space 123. The space between the third flow plate 110c, the fourth flow plate 110d is a second coolant space 121 , and so on. The space between the fourth flow plate 110d and the fifth flow plate 110e is a second refrigerant space 123. The spaces between the flow plates 110 alternate between coolant spaces 121 and refrigerant spaces 123 throughout the series of flow plates 110. As can be seen, in the region of the refrigerant pass-through apertures 113, the first flow plate 110a is sealingly engaged with the second flow plate 110b, the second flow plate 110b is spaced from the third flow plate 110c, the third flow plate 110c is sealingly engaged with the fourth flow plate 110d, and the fourth flow plate 110d is spaced from the fifth flow plate 110e, and so on. Thus, the refrigerant 108 can flow in the refrigerant spaces 123. Additionally, in the region of the coolant pass-through apertures 115, the first flow plate 110a is spaced from the second flow plate 110b, the second flow plate 110b is sealingly engaged with the third flow plate 110c, the third flow plate 110c is spaced from the fourth flow plate 110d, the fourth flow plate 110d is sealingly engaged with the fifth flow plate 110e, and so on. Thus, the coolant 104 can flow in the coolant spaces 121.

[0087] The coolant-refrigerant heat exchanger 100 further includes a secondary heater 122 that is positioned to heat both the refrigerant 108 and the coolant 104 while in the coolant-refrigerant heat exchanger 100. The secondary heater 122 may, for example, extend along the peripheral edge 114 of substantially all of the plurality of flowplates 110 so as to impart heat into each of the flow plates 110 through the height and the width of each of the flow plates 110. The secondary heater 122 may be an electrical resistance heater, such as, for example a PTC heater. Alternatively, the secondary heater 122 may be any other suitable kind of heater, such as, but not limited to, an induction heater, an infrared heater, a microwave heater, or any other kind of heater.

[0088] The secondary heater 122 may include a band heater 122a that extends around substantially the entire length of the peripheral edges 114 of the flow plates 110. Additionally, the secondary heater 122 may include a first end heater 122b that is engaged with the first flow plate 110a for imparting heat into the plurality of flow plates 110 through the thickness of the first flow plate 110a, and a second end heater 122c for imparting heat into the plurality of flow plates 110 through the thickness of the second end cover plate 111. A heat spreader plate 125 may be provided between the second end heater 122c and the second end cover plate 111.

[0089] A feature of the secondary heater 122 is that it is sized to evaporate all of the refrigerant 108 passing through the coolant-refrigerant heat exchanger 100 (i.e. all the refrigerant 108 in the refrigerant flow path 106), so as to ensure that substantially all of the refrigerant 108 can be evaporated in the coolant-refrigerant heat exchanger 100 without any heat input to the refrigerant 108 from the coolant 104 in the coolant flow path 102. In some embodiments, the secondary heater 122 is sized to superheat all the refrigerant in the refrigerant flow path 106 in order to ensure that all of the refrigerant 108 is evaporated and that substantially none of the refrigerant 108 remains in its liquid phase.

[0090] A controller 124 may be provided for controlling the operation of the secondary heater 122. Electrical connections shown at 126 and 128 are provided for providing power to the secondary heater 122 and for providing power to the controller 124.

[0091] A heat exchanger housing 130 may be provided for housing the abovedescribed components. The housing 130 may include a first housing portion 130a and a second housing portion 130b that is sealingly connected to the first housing portion130a. O-rings 132 may be provided for sealing around the apertures shown at 134 in the housing 130 that permit the pass-through of the coolant inlet 118a, the coolant outlet 118b, the refrigerant inlet 116a and the refrigerant outlet 116b. Another seal member 136 is provided between the refrigerant filter 119 and the refrigerant inlet 116a.

[0092] Figure 11 shows a schematic representation of the coolant spaces 121 and the refrigerant spaces 123 and the routing of the coolant flow path 102 and the refrigerant flow path 106 in the embodiment shown in Figures 6-10. As can be seen, the coolant 104 travels from the coolant inlet 118a, through to the coolant spaces 121 and then along the coolant spaces 121 and back to the coolant outlet 118b. Similarly, the refrigerant 108 travels from the refrigerant inlet 116a, through to the refrigerant spaces 123 and then along the refrigerant spaces 123 and back to the refrigerant outlet 116b. Thus, in the embodiment shown in Figure 11 (and Figures 6-10), the coolant outlet 118b and the refrigerant outlet 116b are both at the same end of the plurality of flow plates 110 as the coolant inlet 118a and the refrigerant inlet 116a. In an alternative embodiment shown in Figure 12, the first end cover plate 109 and the second end cover plate 111 are configured to each have one inlet and one outlet. For example, the first end cover plate 109 may have the coolant inlet 118a and the refrigerant outlet 116b, and the second end cover plate 111 may have the coolant outlet 118b and the refrigerant inlet 116a. Thus, the coolant 104 may flow across the flow plates 110 from the first end to the second end, and the refrigerant 108 may flow across the flow plates 110 from the second end to the first end.

[0093] Regardless of whether the coolant flow path 102 and the refrigerant flow path 106 are as shown in Figures 6-11 , or are as shown in Figure 12, the coolant flow path 102 and the refrigerant flow path 106 may be said to be positioned in order to transfer heat from one of the coolant 104 and the refrigerant 108 to the other of the coolant 104 and the refrigerant 108, and the secondary heater 122 may be said to be positioned to heat both the refrigerant 108 and the coolant 104 in the coolant-refrigerant heat exchanger 100.

[0094] Several advantageous features of the coolant-refrigerant heat exchanger 100 are described as follows: The coolant-refrigerant heat exchanger 100 includes aplurality of flow plates 110. It has been found to be effective to provide the secondary heater 122 in the form of a band heater 122a that extends along substantially all of the peripheral edges of the flow plates 110, and also to provide the first end heater 122b, and to provide the second end heater 122c, such that heat is transferred through the height, the width, and through the thickness of the flow plates 110. The peripheral edge heater 122a and the first and second end heaters 122b and 122c may be solid elements formed from sheet material that is joined to the flow plates 110 or to the first and second end cover plates 109 and 111 respectively in any suitable way such as by a suitable adhesive. In some embodiments, one or more of the peripheral edge heater 122a and the first and second end heaters may be in the form of a film heater that is printed directly onto the surface on which it is intended to transfer heat to.

[0095] DESCRIPTION OF LAYOUT OF THERMAL MANAGEMENT SYSTEM INCORPORATING THE NOVEL COOLANT-REFRIGERANT HEAT EXCHANGER

[0096] Reference is made to Figure 13, which shows a thermal management system 150 for an electric vehicle, in accordance with an embodiment of the present disclosure. The electric vehicle is shown at 151 in Figure 14.

[0097] The thermal management system 150 may have a similar layout to the thermal management system 50 shown in Figure 5, and may have a refrigerant system 152 and a coolant system 154. Some differences between the thermal management system 150 and the thermal management system 50 are described as follows. One difference is that the high voltage heater 71 and its associated coolant conduit of Figure 5 are not necessary and are omitted from the thermal management system 150. Additionally, the coolant system 154 includes a battery loop 154a and a motor loop 154b, which are connected to one another by a first transfer conduit 156 and a second transfer conduit 158. The coolant system 154 further includes an additional 3-way valve relative to the coolant system 54 of the thermal management system 50. Thus, the coolant system 154 has a first 3-way valve 160, a second 3-way valve 162 and a third 3-way valve 164, and further has a battery loop pump 166, and a motor loop pump 168. Additionally, the coolant system 154 further includes a coolant check valve 169 on the second transfer conduit 157. Additionally, the coolant system 154 includes a batteryloop bypass conduit 158 and a motor loop bypass conduit 159, which are not present in the coolant system 54. The arrangement of the refrigerant system 152 may be similar to that of the refrigerant system 52. While specific configurations for the coolant system 154 and the refrigerant system 152 are shown and while specific types of valves (e.g. on-off type control valves, 3-way valves, and check valves) are shown, it will be noted that the coolant system 154 and the refrigerant system may be configured differently. As a simple example, the 3 way valves 160, 162 and 164 could be replaced with a plurality of on-off type valves. Another simple example is that the check valves in both the refrigerant and coolant systems 154 and 152 could also be replaced with on-off type control valves. Additionally, the control valves V1 , V2, V3 and V4 and their associated refrigerant conduits could be replaced by a different arrangement of conduits, with a different number of valves including for example one or more 3-way valves.

[0098] A control system, shown at 170, may be provided for controlling the operation of the thermal management system 150. The control system 170 may include a PCB (printed circuit board) 170a on which there is a processor 170b and a memory 170c. The control system 170 may be said to be operatively connected to the control valves V1 , V2, V3 and V4, the expansion valves EXV1 , EXV2 and EXV3, the 3-way valves 160, 162 and 164, and the secondary heater 122 in order to control their operation. Lines representing wires to show the connection between the PCB 170a and the aforementioned valves and secondary heater are not shown in Figure 13 so as not to render these figures more difficult to understand. Furthermore, the control system 170 may include several sensors such as a cabin temperature sensor 172, a refrigerant temperature sensor 174 at the refrigerant inlet 116a of the coolant-refrigerant heat exchanger 100, and a secondary heater temperature sensor 176 which are all connected to the PCB 170a in order to transmit signals to the processor 170b related to the air temperature of the passenger cabin 12, the refrigerant temperature at the refrigerant inlet 116a of the coolant-refrigerant heat exchanger 100 and the temperature of the secondary heater 122, respectively.

[0099] It will be noted that the control system 170 need not include only the single PCB 170a, the processor 170b and the memory 170c. It is alternatively possible for thecontrol system 170 to include a plurality of PCBs at various locations in the electric vehicle 151 , each of which has one or more processors and memory. For example, the PCB 170a may be only a part of the control system 170, and may be part of an ECM (electronic control module) for the electric vehicle 151 that controls the operation of many subsystems in the electric vehicle 151. The control system 170 may further include the controller 124 in the coolant-refrigerant heat exchanger 100. Communication between the PCB 170a and the controller 124 may be via a wired connection or may occur via a wireless connection.

[0100] Furthermore, it is not necessary for any of the temperature sensors 172, 174 and 176 to be directed connected to or to directly communicate with, the PCB 170a. For example, the secondary heater temperature sensor 176 may communicate directly with the controller 124, which in turn, may transmit the information to the PCB 170a.

[0101] A significant difference between the thermal management system 150 and the thermal management system 50 is that the thermal management system 150 includes the coolant-refrigerant heat exchanger 100 instead of the coolant-refrigerant heat exchanger 78.

[0102] Figures 15-21 B illustrate alternative constructions for the coolantrefrigerant heat exchanger 100. In the embodiments shown in Figures 15, 16A and 16B, the secondary heater 122 may be a thick film heater 400. The thick film heater 400 may be positioned on a heat transfer plate 402, that is in turn positioned to transfer heat into the flow plates 110. The thick film heater 400 includes an electrical trace 404. The electrical trace 404 is positioned for carrying a current for resistively heating the heat transfer plate 402, and heating the flow plates 110 via the heat transfer plate 402, in order to transfer heat to any coolant and / or refrigerant in the coolant-refrigerant heat exchanger 100. A portion of the electrical trace 404 is represented as a simple rectangle in Figure 15, in order to illustrate a boundary of an area of the heat transfer plate 402 that is covered by that represented portion of the electrical trace 404. The specific routing of the electrical trace 404 may be any suitable routing (e.g. a serpentine routing) that permits the electrical trace 404 to heat the heat transfer plate 402, preferably generally uniformly.

[0103] The electrical trace 404 may end at first and second electrical terminals shown at 408 and 410, respectively.

[0104] The thick film heater 400 further includes a base electrical insulation layer 403 (shown in Figure 16B) positioned between the electrical trace 404 and the heat transfer plate 402. A top electrical insulation layer (shown at 405 in Figure 16B) may be provided to cover the electrical trace 404. It will be noted that Figure 16B is intended to be a schematic representation of the layers 403, 404 and 405, and their relative thicknesses will vary from what is represented here.

[0105] The thick film heater 400 may be affixed to the heat transfer plate 402 in any suitable way. For example, the various layers making up the thick film heater 400 (e.g. the base electrical insulation layer 403, the electrical trace 404 and the top electrical insulation layer 405) may be applied sequentially by printing. For example, the base electrical insulation layer 403 may be printed directly onto the heat transfer plate 402; the electrical trace 404 may be printed directly onto the base electrical insulation layer 403; and the top electrical insulation layer 405 may be printed over the electrical trace 404 and onto the base electrical insulation layer 403 so as to cover the electrical trace 404.

[0106] The heat transfer plate 402 may be made from any suitable material, such as aluminum or stainless steel. In embodiments in which the thick film heater 400 is to receive current at 800V, it is preferable for the heat transfer plate 402 to be made from a material such as stainless steel, due to its relatively high melting temperature. A reason for this is related to the base electrical insulation layer 403. The base electrical insulation layer 403 is, in some embodiments, made from a material that is initially applied to the heat transfer plate 402 in a form that is not solid. The base electrical insulation layer is then heated (e.g. cured) in order to solidify it. For certain types of material for the base electrical insulation layer 403, it has been found that, if the temperature at which it is heated is too low, it does not solidify in a way that provides good performance as an electrical insulator. By contrast, if it is heated to a temperature that is at least about 800 degrees Celsius (e.g. 850 degrees Celsius), and held there for a suitable amount of time (e.g. about 10 minutes), the base electrical insulation layer403 solidifies in a way that provides strong performance as an electrical insulator. As a result, the base electrical insulation layer 403 may be sufficiently insulative to prevent conduction of a current thereacross at 800V from the electrical trace 404 into the heat transfer plate 402. f

[0107] In embodiments in which the thick film heater 400 is to receive current at 400V, the heat transfer plate 402 may be made more easily from a material such as aluminum. It will be noted that, in either case, (i.e. whether the heat transfer plate 402 is aluminum or stainless steel, the thick film heater 400 is preferably applied to it prior to joining of the heat transfer plate 402 to the flow plates 110.

[0108] The heat transfer plate 402 may be positioned to transfer heat into the flow plates 110 in any suitable way. For example, as shown in Figure 16, the flow plates 110 may have plate peripheral edges shown at 412. The flow plates 110 may be arranged to alternate between a first type of flow plate shown at 414a, which has a first plate peripheral edge 412a, and a second type of flow plate shown at 414b, which has a second plate peripheral edge 412b, which nests laterally inside the first peripheral edge 412a of the subsequent first type of flow plate 414a. As a result, the peripheral edge (shown at 117a) of the flow plate subassembly 117 may be uneven and can include a plurality of peaks and a plurality of valleys, such that the valleys may be referred to as spaces 422 between the flow plates 110 at the peripheral edge 117a of the flow plate subassembly 117. Furthermore, there may be a relatively large tolerance in the exact positions of the peripheral edges 412, thereby contributing further to the unevenness of the peripheral edge 114. In order to provide good heat transfer from the heat transfer plate 402 into the flow plates 110, a suitable form-fitting heat transfer material 420 can be used to at least partially fill at least some of the spaces 422 between the heat transfer plate 402 at the plate peripheral edges 412. For example, the form-fitting heat transfer material 420 may include a suitable soldering material or a brazing material. The suitable soldering material or brazing material has a melting temperature that is lower than that of the flow plates 110, lower than that of the brazing material that is used to join the flow plates 110 together, and lower than that of the heat transfer plate 402. In an example, the soldering or brazing material may have a melting temperature that isbetween about 350 and 400 degrees C. Once in flowable form, the soldering material or brazing material may flow via capillary action through all of the spaces 422 between the heat transfer plate 402 and the plate peripheral edges 412. The soldering material or brazing material may be any suitable soldering material or brazing material, such as, but not limited to, an alloy of tin that includes any suitable alloy materials including for example silver. A person skilled in the art will understand what material to use for the soldering material or brazing material based on the materials to be joined, and based on the temperature restraints and the cost restraints of the application.

[0109] In some other embodiments, the form-fitting heat transfer material 420 may include a thermal paste, a cement, and / or an adhesive.

[0110] More specifically, the form-fitting heat transfer material 420 is positioned in the spaces 422. The form-fitting heat transfer material 420 is thermally conductive, and joins the heat transfer plate 402 to the peripheral edge 117a of the flow plate subassembly 117. Worded another way, the form-fitting heat transfer material 420 is provided between a first heat transfer plate face 402a and the flow plates 110, such that the form-fitting heat transfer material 420 at least partially fills in the spaces 422 between the heat transfer plate 402 and the peripheral edge 117a of the flow plate subassembly 117, and joins the heat transfer plate 402 to the flow plates 110. The thick film heater 400 is positioned on a second heat transfer plate face 402b, which is opposite the first heat transfer plate face 402a.

[0111] It will be noted that, while the terms brazing and soldering may generally be understood to apply in certain temperature ranges, the term ‘soldering or brazing material’ is intended to mean a material that may be soldered, depending on the material selected for the application, or a material that may be brazed, depending on the material selected for the application. In other words, in some embodiments, the soldering or brazing material is a material that can be soldered. In other embodiments, the soldering or brazing material is a material that can be brazed. In some embodiments, the soldering or brazing material is a material that can be brazed or soldered.

[0112] In a particular embodiment, the soldering or brazing material may be heated to 480 degrees C in order to ensure that it is sufficiently flowable to suitably fill the spaces 422 between the heat transfer plate 402 and the plate peripheral edges 412.

[0113] It will be noted that the spaces 422 between the heat transfer plate 402 and the plate peripheral edges 412 need not be fully filled so as to be completely without any voids. It is entirely possible for the spaces 422 between the heat transfer plate 402 and the plate peripheral edges 412 to be mostly filled, and to have sufficient heat transfer from the heat transfer plate 402 into the flow plates 110 so as to avoid the presence of hot spots that could result in damage and failure of the thick film heater 400 (or more broadly worded, damage and failure of the secondary heater 122).

[0114] Optionally, as shown in Figure 17, the heat transfer plates 402 may include a limiting groove 423 that is positioned to interrupt and stop the capillary action of the soldering material or brazing material, thereby limiting the soldering material or brazing material to the region of the heat transfer plate 402 that encompasses the electrical trace 404. As an alternative to the limiting groove 423, or in addition to the limiting groove 423, it is possible to apply a material called an anti-flux compound 424 to stop the capillary action of the soldering material or brazing material. The anti-flux compound 424 could be in the limiting groove 423 so as to work together with the limiting groove 423 (as shown in Figure 17), or, in an embodiment in which the anti-flux compound replaces the limiting groove 423, the anti-flux compound 424 could be in the same position that the groove would have been placed. Only a small segment of the groove 423 is shown with the anti-flux compound therein, so as not to obscure the entire groove 423 in Figure 17, however it will be understood that the entire groove 423 would preferably be covered with the anti-flux compound in embodiments in which the groove 423 is provided and the anti-flux compound 424 is provided in the groove 423.

[0115] In embodiments in which the heat transfer plate includes a quantity of the anti-flux compound 424, the anti-flux compound 424 is positioned to interrupt capillary action of the soldering material or brazing material in the spaces 422 during assembly of the coolant-refrigerant heat exchanger 100, thereby limiting the soldering material or brazing material to a selected region (shown at 427 of the first face 402a of the heattransfer plate 402, that at least partially overlaps with a region of the second face 402b of the heat transfer plate 402 on which the electrical trace 404 is present.

[0116] It will be noted that in embodiments where the form-fitting heat transfer material 420 is a soldering material or a brazing material, the form-fitting heat transfer material 420 transfers heat well from the heat transfer plate 402 to the flow plates 110, and also affixes the heat transfer plate 402 to the flow plates 110. In some situations there is the possibility that the heat transfer plates 402 may delaminate from the flow plates 110. Reference is made to Figure 18, which shows an embodiment of the coolant-refrigerant heat exchanger 100 which includes a mechanical holding member 425 can be provided to hold the heat plate 402 in engagement with the form-fitting heat transfer material 420. The mechanical holding member 425 may be a heat transfer plate biasing member 426 that is positioned between the heat transfer plate 402 and a wall of the heat exchanger housing 130. The heat transfer plate biasing member 426 may be made from a material that is thermally insulative such as an elastomeric material, or may be made from a material that is metallic (which is relatively more thermally conductive than an elastomer), for robustness, if desired. In the event that the heat transfer plate biasing member 426 is made from a material that is electrically conductive, the electrical trace 404 will be covered by the top electrical insulation layer mentioned above.

[0117] The heat transfer plate biasing member 426 can be shaped so as to have a first surface area of contact with the heat transfer plate 426, and a second surface area of contact with the heat exchanger housing 130, wherein the first surface area of contact is smaller than the second surface area of contact so as to reduce heat transfer out of the heat transfer plate 402 to the heat exchanger housing 130. In an alternative embodiment, instead of the heat transfer plate biasing member 426, any other suitable mechanical holding member 425 may be used, such as a clamp (not shown) that clamps against both the heat transfer plates 402 shown in Figure 18, so as to hold them in engagement with the form-fitting heat transfer material 420, or a length of insulated cable that is wrapped around the flow plates 110 and the heat transfer plates 402 tohold the heat transfer plates in engagement with the form-fitting heat transfer material 420.

[0118] Reference is made to Figures 19A-19H, which show another embodiment of the coolant-refrigerant heat exchanger 100. In the embodiment shown in Figures 19A-19H, there are heater receiving apertures shown at 450 that extend through at least some of the flow plates 110, and cartridge heaters shown at 452 that are positioned in the heater receiving apertures 450. The cartridge heaters 452 may be formed with relatively tight tolerances, which improves the amount of contact between the outer surface (shown at 454) of the cartridge heater 452 and the wall of the heater receiving aperture 450, thereby improving the heat transfer from the cartridge heaters 452 into the flow plates 110.

[0119] As can be seen, it is optionally possible for the heater receiving apertures 450 to extend through all of the flow plates 110. Figure 19B shows a single flow plate 110 with two flow plate heater apertures 456, which form aperture segments of the heater receiving apertures 450.

[0120] Figures 19C and 19D illustrate an embodiment in which a heater receiving tube 457 is inserted into each of the heater receiving apertures 450, for receiving the cartridge heater 452. The tube may be brazed to the flow plates 110 in the

[0121] Figures 19F, 19G, and 19H show that the cartridge heaters 452 can come in different configurations, e.g. with a heating element 458a that extends along only about 50% of the length of the cartridge heater 452 and which heats uniformly along that 50% (Figure 19G), a heating element 458b that extends along about 90% of the length of the cartridge heater 452, and which heats uniformly along that 90% (Figure 19F), and a heating element 458c that extends along about 80% of the length of the cartridge heater 452 and which heats more towards the ends of the heating element 458c, then in the middle of the heating element 458c (Figure 19H). Different types of cartridge heater 452 could be used in different heater receiving apertures, in order to achieve a selected heat transfer through to different regions in the flow plates 110,particularly in embodiments where there are more than two heater receiving apertures 450 and cartridge heaters 452.

[0122] Figure 19E shows the cartridge heater 452 with an optional temperature sensor incorporated therein, to facilitate control of the operation of the cartridge heater 452 and the amount of heat transferred from it to the flow plates 110. For example, the cartridge heaters 452 may be selected to have different amounts of power in order to provide a uniform amount of heat transfer to all regions of the flow plates 110.

[0123] Reference is made to Figures 20A and 20B, which show another embodiment of the coolant-refrigerant heat exchanger 100. In this embodiment, the thick film heater 400 may be applied to the heat transfer plate 402. The heat transfer plates 402 with the thick film heaters 400 thereon, and the assembly of the flow plates 110 may be placed in the heat exchanger housing 130. In addition, a quantity of a suitable particulate material 460, such as magnesium oxide, may be placed in the heat exchanger housing 130, to transfer heat from the heat transfer plates 402 to the flow plates 110. In Figure 20B only a few disparate dots are shown which are intended to represent the particulate material 460. It will be understood that the actual particulate material will be densely packed in the spaces between the heat transfer plates 402 and the flow plates 110. The particulate material 460 is a material that has a relatively high thermal conductivity. When the particulate material 460 is placed in the housing 130 to fill the spaces between the heat transfer plates 402 and the flow plates 110, it is preferable that the particulate material 460 be packed into the housing with a relatively high packing density, in order to improve the heat transfer.

[0124] It will be noted that only two sides of the peripheral edge 114 are shown as having thick film heaters 400 and heat transfer plates 402 thereon. It will be noted that a thick film heater 400 and a heat transfer plate 402 could be provided on any nonzero portion of the peripheral edge 114. For example, there could be four thick film heaters 400 and heat transfer plates 402, one on each side of the peripheral edge 114.

[0125] In general, when reference is made to heat transfer to the flow plates 110 of the coolant-refrigerant heat exchanger 100, it will be understood that heat transfer isbeing made to any coolant and / or refrigerant that is present in the coolant-refrigerant heat exchanger 100.

[0126] In another embodiment, a die-castable material may be used in a die casting process to fill any spaces between the heat transfer plate 402 and the flow plates 110. For example, the die-castable material may be a zinc alloy, or may be any other suitable type of material. Such an embodiment is shown in Figures 21 A and 21 B. In Figures 21 A and 21 B, the secondary heater (e.g. the thick film heater 400) is shown as a simple rectangle, for simplicity, however, it will be understood to have a suitable routing and terminals as shown in the other embodiments disclosed herein.

[0127] The die-cast material may include a main layer 480 between the heat transfer plate 402 and the flow plate subassembly 117 and a plurality of rivets 482 that extend through a plurality of apertures 484 in the heat transfer plate 402 and engage the second heat transfer plate face 402b to hold the heat transfer plate 402 against the main layer 480.

[0128] To produce this version of the coolant-refrigerant heat exchanger 100, the flow plate subassembly 117 may be placed in a suitable mold and the die-cast material may be injected as needed and cooled so as to form the main layer 480 and the rivets 482.

[0129] While the description contained herein constitutes a plurality of embodiments of the present invention, it will be appreciated that the present invention is susceptible to further modification and change without departing from the fair meaning of the accompanying claims.

[0130] LIST OF ITEMS

Claims

CLAIMSWhat is claimed is:

1. A coolant-refrigerant heat exchanger for a thermal management system for an electric vehicle, comprising: a coolant flow path for transporting coolant therethrough; a refrigerant flow path for transporting refrigerant therethrough, wherein the coolant flow path and the refrigerant flow path are positioned in order to transfer heat from one of the coolant and the refrigerant to the other of the coolant and the refrigerant, wherein the coolant-refrigerant heat exchanger includes a flow plate subassembly that includes a plurality of flow plates joined together, wherein the plurality of flow plates together define the coolant flow path and the refrigerant flow path, each of the plurality of flow plates having a plurality of faces and a peripheral edge, the flow plate subassembly having a peripheral edge that is made up of the peripheral edges of the flow plates, wherein there are a plurality of spaces between the plurality of flow plates at the peripheral edge of the flow plate subassembly; a heat transfer plate having a first heat transfer plate face that faces the flow plate subassembly and a second heat transfer plate face that is opposite the first heat transfer plate face; a form-fitting heat transfer material positioned in the spaces, wherein the formfitting heat transfer material is thermally conductive, and joins the heat transfer plate to the peripheral edge of the flow plate subassembly; and a secondary heater that is positioned on the second heat transfer plate face, wherein the secondary heater is energizable to heat both the refrigerant and the coolant in the coolant-refrigerant heat exchanger by heat conduction through the heat transfer plate, the formfitting heat transfer material and the flow plates.

2. The coolant-refrigerant heat exchanger as claimed in claim 1 , wherein the formfitting heat transfer material is a soldering material or brazing material.

3. The coolant-refrigerant heat exchanger as claimed in claim 2, wherein the secondary heater includes an electrical trace, and wherein the heat transfer plate includes a limiting groove that is positioned to interrupt capillary action of the soldering material or brazing material in the spaces during assembly of the coolant-refrigerant heat exchanger, thereby limiting the soldering material or brazing material to a selected region of the first face of the heat transfer plate, that at least partially overlaps with a region of the second face of the heat transfer plate on which the electrical trace is present.

4. The coolant-refrigerant heat exchanger as claimed in claim 2, wherein the secondary heater includes an electrical trace, and wherein the heat transfer plate includes a quantity of an anti-flux compound that is positioned to interrupt capillary action of the soldering material or brazing material in the spaces during assembly of the coolant-refrigerant heat exchanger, thereby limiting the soldering material or brazing material to a selected region of the first face of the heat transfer plate, that at least partially overlaps with a region of the second face of the heat transfer plate on which the electrical trace is present.

5. The coolant-refrigerant heat exchanger as claimed in claim 1 , wherein the heat transfer plate is stainless steel and the thick film heater is connected to a voltage source to receive current at a voltage of 800V.

6. The coolant-refrigerant heat exchanger as claimed in claim 1 , further comprising a mechanical holding member, wherein the mechanical holding member holds the heat transfer plate in engagement with the form-fitting heat transfer material.

7. The coolant-refrigerant heat exchanger as claimed in claim 1 , wherein the formfitting heat transfer material is a die cast material.

8. The coolant-refrigerant heat exchanger as claimed in claim 7, wherein the formfitting heat transfer material includes a main layer between the heat transfer plate and the flow plate subassembly and a plurality of rivets that extend through a plurality of apertures in the heat transfer plate and engage the second heat transfer plate face to hold the heat transfer plate against the main layer.

9. The coolant-refrigerant heat exchanger as claimed in claim 1 , wherein the formfitting heat transfer material partially fills at least some of the spaces between the heat transfer plate at the flow plates at the flow plate assembly peripheral edge.

10. The coolant-refrigerant heat exchanger as claimed in claim 1 , wherein the secondary heater is a thick film heater.

Images