WO2012003209A1

WO2012003209A1 - Vehicle battery temperature control system and method

Info

Publication number: WO2012003209A1
Application number: PCT/US2011/042337
Authority: WO
Inventors: Ronald S. Eisenhour
Original assignee: Nissan North America Inc
Current assignee: Nissan North America Inc
Priority date: 2010-06-30
Filing date: 2011-06-29
Publication date: 2012-01-05
Anticipated expiration: 2012-12-30

Abstract

A vehicle battery temperature control system includes a battery (14), a housing (16), a heat exchanger (18) and a sensor (32). The battery (14) has a heat sink (20). The housing (16) has a chamber (24) that contains the battery (14) and saturated liquid coolant (26) that substantially immerses the heat sink (20) to receive the thermal energy to cause a phase change of the coolant (26) from a liquid to a vapor. The heat exchanger (18) removes thermal energy from the vapor to change the vapor to liquid, and returns the liquid to the chamber (24). Either a valve (38, 40) selectively conveying coolant (26) between the chamber (24) to an air-conditioning system or a heating device (52) is controlled based on a characteristic of the coolant (26) detected by the sensor (32) to remove or provide thermal energy to or from the coolant (26) based on a relationship between the characteristic of the coolant (26) and a threshold.

Description

NM10-01812

VEHICLE BATTERY TEMPERATURE CONTROL SYSTEM AND

METHOD

BACKGROUND

Field of the Invention

[0001] The present invention generally relates to a vehicle battery temperature control. More specifically, the present invention relates to a vehicle battery temperature control system and method that use liquid phase and vapor phase coolant to maintain desired battery temperature.

Background Information

[0002] A hybrid electric vehicle (HEV) or full electric vehicle relies substantially or completely on battery power for operation. Therefore, it is desirable to maintain the battery cells at an optimal operating temperature. As understood in the art, battery cells are often best suited to operate in a somewhat small optimum temperature range.

Consequently, the life or durability of the battery, as well as the performance of the battery, such as the available power provided by the battery, can be adversely affected by temperatures above and below that optimum temperature range. Furthermore, to optimize battery performance, it is essential to maintain temperature uniformity among the cells of a battery, for example, multiple battery cells assembled in a battery module.

[0003] Typically, batteries of HEVs or full electric vehicles can be cooled by air, or by a liquid coolant that, for example, has a high water content. However, when cooling fluid is provided by a pumping mechanism, such as a fan or liquid pump, in a single phase (e.g., a liquid phase), temperature gradients will exist along the flow path. That is, because heat is transferred at all points along the flow path, the temperature of the liquid coolant increases from the entrance to the exit of the battery assembly. These gradients can be somewhat reduced by increasing fluid flow rate, which consumes greater energy. Also, shortened parallel flow paths along the cells can be used instead of a serial flow path.

[0004] Some systems use the vehicle's air-conditioning (A/C) system refrigerant to cool the battery structure as a primary fluid, or through a secondary fluid which is commonly referred to as a chiller design. With this type of arrangement, a considerable amount of energy is expended to pump the refrigerant and achieve the desired cooling NM 10-01812 effects. Moreover, if the A/C system does not operate, the refrigerant will eventually all vaporize within the battery assembly, and as a consequence, the pressure and temperature inside the battery assembly will elevate. This elevation in pressure and/or temperature could result in lost battery performance due to temperature gradients that compromise the optimum operating temperature. Typically, the coldest temperature of the A/C cycle is used to provide the cooling effect. This temperature is generally around 5 degrees Celsius, which is colder than the optimum operating temperature range of the battery. Accordingly, a control system is required that, for example, modulates or pulses the flow of cold refrigerant into the battery assembly so as not to overcool the battery. However, this flow modulation can result in the coolant departing from the saturated state, and can create large and detrimental temperature gradients within the battery assembly, thus degrading the battery's life and performance. Furthermore, when the local refrigerant becomes superheated vapor, its temperature will rise due the added heat, thus decreasing the cooling capability. Also, a chiller design will likely have a fluid in the liquid state that will similarly increase in temperature with the added heat.

[0005] In addition, batteries of HEV and full electric vehicles either rely on internal heat generation or heating of an adjacent fluid (e.g., air or coolant) as the main means to reach the ideal operating temperature range for their battery. As discussed above, consequences to battery life and performance at temperatures above and below that temperature range are very undesirable, and temperature uniformity among battery cells is essential to optimize performance.

[0006] Accordingly, when single phase (e.g., vapor or liquid) flow of a heated fluid is provided by some type of pumping mechanism (e.g., a fan or liquid pump) as discussed above, temperature gradients will exist along its flow path because heat is transferred at all points along the path. Therefore, the heating fluid temperature decreases from the entrance to the exit of the battery assembly, which could create temperature gradients in the battery that degrade performance. Also, internal battery heating may be a slow process, and therefore, a significant period of time colder than the ideal operating temperature may exist, which can have adverse effects such as reduce driving range as discussed above. Alternatively, multiple heaters can be used in the battery itself to attempt to evenly heat the cells of the battery. However, this arrangement would require that the temperature of NM 10-01 812 each cell be monitored and the appropriate power level be applied to each heater, thus making the arrangement complicated and costly.

SUMMARY

[0007] It has been discovered that to improve temperature control for a vehicle battery, coolant in liquid and vapor phase can be used, and the coolant can be replenished as necessary or thermal energy can be added to the coolant to increase the coolant

temperature as desired.

[0008] In view of the state of the known technology, one aspect of the present invention is to provide a vehicle battery temperature control system including a battery, a housing, a heat exchanger, a valve and a sensor. The battery is operable to discharge thermal energy, and has a heat sink configured to transfer the thermal energy from the battery. The housing has a chamber that is configured to receive the battery and contain a saturated liquid coolant that substantially immerses the heat sink so that the coolant receives the thermal energy from operation of the battery to cause a phase change of the coolant from a liquid phase to a vapor phase. The heat exchanger is configured to receive vapor phase coolant from the chamber and remove thermal energy from the vapor phase coolant to change the coolant from the vapor phase to the liquid phase, and is further configured to return the liquid phase coolant to the chamber. The valve is operable to selectively fluidly couple the chamber to an air-conditioning refrigeration system to enhance cooling of the coolant in the chamber. The sensor is operable to detect a characteristic of the coolant and to signal operation of the valve to fluidly couple the chamber to the air-conditioning refrigeration system to increase removal of thermal energy from the coolant based on a relationship between the characteristic of the coolant and a threshold.

[0009] In view of the state of the known technology, another aspect of the present invention is to provide a vehicle battery temperature control system comprising a battery, a heating device, a housing, a heat exchanger and a sensor. The battery has a heat sink configured to transfer thermal energy to the battery. The heating device is selectively operable to provide thermal energy. The housing includes a chamber that is configured to receive the battery and contain a saturated liquid coolant that substantially immerses the heat sink so that the coolant receives the thermal energy from the heating device to cause a NM10-01812 phase change of the coolant from a liquid phase to a vapor phase to heat the heat sink to enable the heat sink to heat the battery. The heat exchanger is configured to receive vapor phase coolant from the chamber and remove thermal energy from the vapor phase coolant to change the coolant from the vapor phase to the liquid phase, and is further configured to return the liquid phase coolant to the chamber. The sensor is operable to detect a characteristic of the vapor phase coolant and to signal operation of the heating device to provide the thermal energy based on a relationship between the characteristic of the vapor phase coolant and a threshold.

BRIEF DESCRIPTION OF THE DRAWINGS

[0010] Referring now to the attached drawings which form a part of this original disclosure:

[0011] Figure 1 is an exemplary diagram of an electric vehicle employing a vehicle battery temperature control system in accordance with an illustrated embodiment;

[0012] Figure 2 is a detailed exemplary diagram of the vehicle battery temperature control system employed in the vehicle shown in Figure 1 ;

[0013] Figure 3 is a graph illustrating an exemplary relationship between the percentage of coolant liquid by volume versus the coolant liquid temperature in the system of Figure 2;

[0014] Figure 4 is a graph illustrating an exemplary relationship between the saturated coolant pressure and the coolant liquid and vapor temperature in the system of Figure 2;

[0015] Figure 5 is a detailed exemplary diagram of the vehicle battery temperature control system employed in the vehicle shown in Figure 1 ;

[0016] Figure 6 is a detailed exemplary diagram of another embodiment of the vehicle battery temperature control system employed in the vehicle shown in Figure 1 ;

[0017] Figure 7 is a detailed exemplary diagram of a further embodiment of the vehicle battery temperature control system employed in the vehicle shown in Figure 1 ;

[0018] Figure 8 is a detailed exemplary diagram of still another embodiment of the vehicle battery temperature control system employed in the vehicle shown in Figure 1 ; and

[0019] Figure 9 is a detailed exemplary diagram of still another embodiment of the vehicle battery temperature control system employed in the vehicle shown in Figure 1. NM10-01812

DETAILED DESCRIPTION OF EMBODIMENTS

[0020] Selected embodiments will now be explained with reference to the drawings. It will be apparent to those skilled in the art from this disclosure that the following descriptions of the embodiments are provided for illustration only and not for the purpose of limiting the invention as defined by the appended claims and their equivalents.

[0021] Referring initially to Figures 1 and 2, a portion of an electric vehicle 1 is partially illustrated with a vehicle battery temperature control system 10 in accordance with a first embodiment. In the figures, an arrow FR indicates a frontward direction of the vehicle, and an arrow UP indicates an upward direction of the vehicle.

[0022] In this embodiment, the vehicle 1 includes a vehicle body 2 that supports a power unit 3 that includes an electric motor 3M and a reduction gear 3R. The electric motor 3M and the reduction gear 3R are configured as a single integrated unit. The electric motor 3M is installed in a front section of the vehicle body 2. The electric motor 3M is operatively coupled to a pair of front wheels Wf in a conventional manner to rotate the front wheels Wf. Thus, the electric motor 3M propels the vehicle 1. In addition to the electric motor 3M, various comparatively heavy electrical components are mounted on the vehicle body 2. In particular, as shown in Figures 1 and 2, the vehicle body 2 also supports various comparatively heavy electrical components including, but not limited to, an inverter 4, a circuit box 5, a charger (not shown) and a battery unit 7.

[0023] In this embodiment, the electric motor 3M, the inverter 4 and the circuit box 5 are arranged in a frontward portion of the vehicle 1. Meanwhile, the battery unit 7 is arranged in a longitudinally middle portion of the vehicle 1 and the charger (not shown) is arranged in a rearward portion of the vehicle 1. In this way, several electrical components are arranged to be distributed appropriately in the longitudinal direction of the vehicle 1 such that the weight of the vehicle 1 can be more easily balanced with respect to the longitudinal direction.

[0024] As shown in Figure 1, a front compartment 8 is formed in a frontward portion of the vehicle 1. The front compartment 8 is a space surrounded by a dash panel 9 on a rearward side, a fender panel (not shown) on each of both width wise sides, and a bumper (not shown) and grill (not shown) on a frontward side. A hood 11 is arranged and configured such that the hood 11 can open and close an upper opening of the front NMl O-01.812 compartment 8. The power unit 3 (the electric motor 3M and the reduction gear 3R), the inverter 4, the circuit box 5, and other components are housed inside the front

compartment 8.

[0025] While only one charging port 12 is illustrated, typically, two or more charging ports could be provided. A low-voltage charging port would be provided to conduct charging at a comparatively low (household) voltage (e.g., 100V or 200V). A high- voltage charging port would be provided to conduct charging at a comparatively high voltage (e.g., 500 V). The charging harnesses 13 are connected to the charging ports. Low- voltage electric power supplied to the low- voltage charging port from a low-voltage power supply cord is converted to a higher voltage by the charger (which includes a transformer (not shown) for converting a low voltage to a higher voltage) and the higher voltage power is supplied to the battery cells of a battery 14 (Figure 2) inside the battery unit 7 through the circuit box 5 (conductor portions inside the circuit box 5). High-voltage electric power supplied to the high- voltage charging port from a high-voltage power supply cord is supplied to the battery 14 inside the battery unit 7 through the circuit box 5 (conductor portions inside the circuit box 5). The high-voltage charging port enables charging to be completed at a faster rate. In addition to the transformer, the charger is also provided with additional electrical components such components as a rectifier circuit for converting alternating current to direct current and a filter.

[0026] As shown in more detail in Figure 2, in addition to the battery 14, the vehicle battery temperature control system 10 also includes a housing 16 and a heat exchanger 18. The battery 14 includes a plurality of stacked battery cells 17 and a heat sink 20 that can be configured as a single heat sink or a plurality of heat sinks, and can have any suitable heat exchange features as understood in the art. During operation, the battery 14 becomes heated and thus discharges thermal energy. The heat sink 20 can transfer the thermal energy generated by the battery 14 away from the battery 14, or can transfer thermal energy to the battery 14.

[0027] The housing 16 includes an insulation member 22 configured to substantially enclose the housing 16. As illustrated, the battery 14 and heat sink 20, housing 16, insulation member 22 and associated components described herein are included in the battery unit 7 shown in Figure 1. The housing 16 defines a chamber 24 that is configured NT-W0105 ! 56

NM 10-01.812 to receive the battery 14 and contain a saturated liquid coolant 26 that substantially immerses the heat sink 20 so that the coolant receives the thermal energy from operation of the battery 14 to cause a phase change of the coolant from a liquid phase to a vapor phase. In this example, the coolant 26 includes 1,1,1,2-Tetrafluoroethane (known as R- 134a) or 2,3,3,3-Tetrafluoroprop-l-ene (known as HFO-1234yf). However, the coolant 26 can include any suitable type of liquid or refrigerant. Furthermore, the chamber 24 can be configured such that the saturated liquid coolant 26 in the chamber 24 completely immerses the heat sink 20. As shown in graph 50 of Figure 3, the liquid volume of common types of refrigerants is reasonably stable across the expected ambient temperature range.

[0028] The heat exchanger 18 is configured in an elevated position with respect to the chamber 24 to receive vapor phase coolant from the chamber 24 and remove thermal energy from the vapor phase coolant to change the coolant from the vapor phase to the liquid phase. In this example, the heat exchanger 18 is positioned substantially above a level of the saturated liquid coolant in the chamber 24, and receives the vapor phase coolant from the chamber 24 via a conduit 28 that can be a tube made of rubber, metal or any other suitable material. The heat exchanger 18 is further configured to return the liquid phase coolant to the chamber 24 via a conduit 30 that can be a tube made of rubber, metal or any other suitable material. In one configuration, the heat exchanger 18 includes a condenser that is fluidly coupled to receive the vapor phase coolant from the chamber 24 via conduit 28. The condenser is operable to remove heat from the vapor phase coolant to create the liquid phase coolant, and is fluidly coupled to return the liquid phase coolant to the chamber 24 via conduit 30.

[0029] It should be noted that the insulation member 22 ensures that the management of the temperature in the chamber 24 is principally controlled at the heat exchanger 18 (condenser). This is particularly beneficial when, for example, the battery 14 is a cold battery pack operating in a low ambient temperature condition. By limiting heat transfer or adding heat, for example, through warm airflow from the passenger cabin to the condenser, the self heating of the battery 14 can be used to reach the optimum operating temperature range. NM10-01812

[0030] As further shown in Figure 2, the system 10 includes a sensor 32, a controller 34, a sensor 36, a valve 38 and a valve 40. The sensors 32 and 36, the controller 34 and the valves 38 and 40 are conventional components that are well known in the art. Since these components are well known in the art, these structures will not be discussed or illustrated in significant detail herein. Rather, it will be apparent to those skilled in the art from this disclosure that the components can be any type of structure and/or programming that can be used to carry out the present invention.

[0031] The controller 34 can be any suitable type of computer, microprocessor or control device as known in the art. The controller 34 preferably includes a microcomputer with a control program that controls the operations as discussed below. The controller 34 can also include other conventional components such as an input interface circuit, an output interface circuit, and storage devices such as a ROM (Read Only Memory) device and a RAM (Random Access Memory) device. A memory circuit (not shown) stores processing results and control programs such as ones for the operations discussed herein. It will be apparent to those skilled in the art from this disclosure that the precise structure and algorithms for the controller 34 can be any combination of hardware and software that will carry out the functions of the vehicle battery temperature control system 10.

[0032] As discussed in more detail below, the valves 38 and 40 are each operable to selectively fluidly couple the chamber 24 to an air-conditioning (A/C) refrigeration system (not shown) to enhance cooling of the coolant 26 in the chamber 24. In other words, because the coolant 26 and the coolant in the A/C system are identical or similar enough to be compatible with each other, the operation of the compressors in the A/C system can pump coolant into the chamber 24 to replenish the coolant 26 in the chamber 24, and can pump coolant out of the chamber 24 to reduce the temperature and pressure in the chamber 24.

[0033] Specifically, the valve 38 in this example is a vapor collection valve operable to receive the vapor phase coolant from the chamber 24 and is coupled to a low pressure side of the A/C refrigeration system. The valve 40 in this example is a return valve configured to provide the liquid phase coolant from a high pressure side of the air- conditioning refrigeration system to the chamber 24 in the housing 16. NM10-01812

[0034] Also, the sensors 32 and 36 are each operable to detect a characteristic of the coolant 26 and to signal operation of a respective valve 38 or 40 to fluidly couple the chamber 24 to the air-conditioning refrigeration system to increase removal of thermal energy from the coolant 26 when the characteristic of the coolant 26 is above or below a respective threshold. That is, the controller 34 receives the signals from the sensors 32 and 36 and operates the appropriate valve 38 and/or 40 to fluidly couple the chamber 24 to the air-conditioning refrigeration system when the sensor 32 and/or 36 senses that the characteristic of the coolant 26 is above or below the respective thresholds.

[0035] Specifically, the sensor 32 is operable to detect when the characteristic, which represents a characteristic of the vapor phase coolant, is above the threshold, and is operable to signal the operation of the valve 38 to increase the removal of thermal energy when the characteristic is above the threshold. The sensor 32 includes, for example, a temperature sensor operable to sense a temperature of the coolant 26 in the chamber 24 as the characteristic. An example of the relationship of the pressure versus the liquid coolant temperature is shown in graph 60 of Figure 4, with the A/C low side temperature operating range being identified by area 62, and the optimum battery temperature range being identified by area 64. Hence, the threshold can be an upper temperature threshold, such as a temperature threshold at or about 45 degrees Celsius.

[0036] Alternatively, or in addition, the sensor 32 includes a pressure sensor operable to sense a pressure in the chamber 24 as the characteristic. In this event, the threshold can be an upper pressure threshold, such as pressure at or about 1100 kPa (see Figure 4).

Naturally, any suitable temperature threshold or pressure threshold can be used. On the other hand, the sensor 36 includes a liquid level sensor configured to detect a level of the liquid phase coolant in the chamber 24 of the housing 16 as the characteristic, and to signal the operation of the valve 40 when the level is sensed as being below the desired threshold level.

[0037] Concerning the operation of the system 10, it is understood in the art that when a fluid, such as the coolant 26, is contained in a saturated state, coolant in the liquid phase and in the vapor phase coexist at a specific temperature and pressure within the chamber 24. When heat (thermal energy) is added due to, for example, heating of the battery 14 during operation of the battery 14, temperature uniformity is maintained by the fluid NM10-01812 vaporizing at the same or substantially the same pressure. This temperature stability and uniformity maintains the cells of the battery 14 at the same or substantially the same temperature within the battery 14.

[0038] Moreover, since the phase change from a low energy content liquid phase to a high energy content vapor phase results in a density change, vapor bubbles are separated from the liquid by gravity. That is, vapor bubbles rise to the upper part of the chamber 24. Accordingly, the vapor phase coolant can flow via the conduit 28 into the heat exchanger 18, and is thus transported away from the heat source (i.e., the battery 14) without a pumping mechanism. Moreover, the formation of bubbles absorbs considerable energy without causing a rise in temperature of the coolant 26, and the mixing action of the bubbles in moving toward the free surface of the coolant 26 toward the upper part of the chamber 24 further enhances the temperature uniformity in the battery 14.

[0039] Also, since the liquid phase coolant 26 is in a saturated state, temperature uniformity is maintained throughout the battery 14, and the change from the liquid phase to the vapor phase is used to quickly and naturally transport high energy content vapor phase coolant 26 to the heat exchanger 18, due to the vapor density of the vapor phase coolant 26 being much less than that of the surrounding liquid phase coolant 26. This action further enhances the convective heat transfer within the battery 14.

[0040] Accordingly, the heat transfer from the vapor phase coolant to the environment external of the system 10 can be managed with the condensing heat exchanger (condenser) 18, with the assistance of a fan 37 (Figure 1) as needed. However, as discussed below, the operation of the valves 38 and 40 to couple to the A/C system to perform cooling can render the fan unnecessary. The reformation of liquid phase coolant from the vapor phase coolant by the heat exchanger 18 thus maintains the target pressure and corresponding target temperature of the coolant 26, which results in a stable temperature environment for the battery cell heat sink structure. The system 10 is inherently isothermal and does not require forced fluid flow within the battery 14 to perform the required heat exchange functions. Rather, the system 10 allows for the natural flow of high energy vapor phase coolant to the heat exchanger 18 as discussed above, instead of requiring, for example, a pump to force the flow of coolant to a heat exchanger. NM10-01812

[0041] However, when the transfer of thermal energy by the heat exchanger 18, and thus the condensing, is insufficient, the sensor 32 will detect that the temperature and/or pressure in the chamber 24 are above their respective thresholds. Accordingly, the sensor 32 will signal the controller 34 to open the valve 38 to access the low side of the A/C system to drop the pressure in the chamber 24. In other words, the opening of the valve 38 allows the vapor phase coolant in the chamber 24 to "boil off into the low side of the A/C system. This reduction in pressure in the chamber 24 causes a reduction in temperature of the coolant 26, and thus provides a rapid cooling effect. That is, since the coolant 26 is in a saturated state, changes in the pressure in the chamber 24 with result in a phase change that will absorb the heat of vaporization of the coolant 26. Once the sensor 32 senses that the temperature and/or pressure has decreased to below the prescribed threshold, the sensor 32 signals the controller 34 to close the valve 38.

[0042] In addition, when the sensor 36 determines that the level of the coolant 26 in the chamber 24 has receded to below a prescribed threshold level due to, for example, the boiling off of coolant 26 into the low side of the A/C system as discussed above, the sensor 36 signals to the controller 34 to open the valve 40. This prescribed threshold level can be a level sufficient to entirely or substantially submerge the heat sink 20, or any desired level. When the valve 40 is opened, the compressor of the A/C system can move coolant from the high side of the A/C cycle into the chamber 24 to replenish the coolant level.

[0043] In particular, the refrigerant that is used to replenish the coolant level in the chamber 24 is provided from the post-condenser high pressure portion of the A/C cycle. Hence, the refrigerant is, by design, almost entirely liquid that is hotter than the ambient temperature. When the refrigerant is throttled through valve 40 to replenish the chamber 24, some of the liquid will turn to vapor and achieve the internal saturated

temperature/pressure relationship. Thus, liquid is added to the pool within the system 10. The sensor 36 is used to manage this liquid quantity, in order keep the heat sink 20 submerged or, in other words, covered by the liquid coolant.

[0044] Furthermore, the access to the low pressure side of the A/C cycle ideally is brief, and removal of vapor coolant occurs quickly through valve 38 and can be modulated by the controller 34, to keep the saturation temperature no colder than the target operating NM10-01812 temperature range (e.g., no colder than about 18 degrees Celsius). Once the sensor 36 senses that the level of the coolant 26 has reached the prescribed threshold level, the sensor 36 signals to the controller 34 to close the valve 40. Also, in an extreme case, such as the onset of battery thermal runaway, which is the concurrent escalation of current and temperature that could lead to destruction of the battery 14, the above features might be used to over-cool the batteries to save the battery 14 from destruction.

[0045] As can be further appreciated from the above, the system 10 does not generally require a forced flow of the coolant 26 by, for example, a pump to enable the heat exchanger 18 to perform the normal heat exchange functions to maintain the temperature and pressure in the chamber 24 within the ranges for optimum battery operation. However, even if the valves 38 and/or 40 are operated to access the cooling power of the A/C system, the system 10 maintains a reserve of liquid coolant in the A/C system and further maintains an isothermal condition in the system 10. Hence, the A/C system can be used to achieve rapid cooling, which may be important in extreme situations, while still

maintaining the isothermal condition in the system 10.

[0046] Referring now to Figure 5, a vehicle battery temperature control system 1 OA in accordance with a second embodiment will now be explained. In view of the similarity between the first and second embodiments, the parts of the second embodiment that are identical to the parts of the first embodiment will be given the same reference numerals as the parts of the first embodiment. Moreover, the descriptions of the parts of the second embodiment that are identical to the parts of the first embodiment may be omitted for the sake of brevity. The parts of the second embodiment that differ from the parts of the first embodiment will be indicated with different reference numerals.

[0047] As shown in Figure 5, the vehicle battery temperature control system 10A mainly differs from the vehicle battery temperature control system 10 in that the vehicle battery temperature control system 10A further includes a heating device 52 and

eliminates the sensor 36 and the valves 38 and 40. Here in the vehicle battery temperature control system 10A, the controller 34 is programmed to control the fan 37 and the heating device 52 in response to a signal provided by the sensor 32 as explained below.

[0048] Here in the vehicle battery temperature control system 10A, the sensor 32 is operable to detect when a characteristic of the vapor phase coolant is above a threshold, NM10-01812 and to signal operation of the fan 37 that increases the removal of thermal energy by the heat exchanger 18 when the characteristic is above the threshold. In this example, the sensor 32 provides a signal to the controller 34 which determines whether the

characteristic is above the threshold. If the characteristic is above the threshold, the controller 34 controls the fan 37 to operate. The fan 37 can be configured as a single fan or multiple fans.

[0049] The sensor 32 is operable to sense a temperature of the vapor phase coolant in the chamber 24 as the characteristic. In this event, the threshold can be an upper temperature threshold, such as a temperature threshold at or about 45 degrees Celsius. Alternatively, or in addition, the sensor 32 is operable to sense a pressure in the chamber 24 as the characteristic. In this event, the threshold can be an upper pressure threshold, such as pressure at or about 1100 kPa. Naturally, any suitable temperature threshold or pressure threshold can be used.

[0050] The battery 14 can be permitted to heat up when the cooling fan 37 is not being operated, and can be maintained at approximately the ambient air temperature of the heat exchanger 18 when the cooling fan 37 is operated. In addition, varied airflow provided by fan 37 to the heat exchanger 18 assists in managing the pressure and corresponding operating temperature of the coolant 26 and battery 14. As discussed above, a temperature and/or pressure sensor 32 is used to signal the controller 34 to operate the cooling fan 37 in the appropriate manner to achieve the desired temperature of the coolant 26. The source of the airflow provided by the fan 37 can be air external to the vehicle 1 that is drawn in by the fan 37. Also, the source of the airflow can be pre-cooled or pre-heated air that is provided, for example, by the heating ventilating and air-conditioning (HVAC) system of the vehicle 1 or other means to assist the fan 37 and the heat exchanger 18 in maintaining the coolant 26, and thus the battery 14, within the target temperature range.

[0051] Accordingly, the heat transfer from the vapor phase coolant to the environment external of the system 10 can be managed with the condensing heat exchanger (condenser) 18 and the cooling fan 37. The reformation of liquid phase coolant from the vapor phase coolant by the heat exchanger 18 thus maintains the target pressure and corresponding target temperature of the coolant 26, which results in a stable temperature environment for the battery cell heat sink structure. The system 10A is inherently isothermal and does not NM10-01812 require forced fluid flow within the battery 14 to perform the required heat exchange functions. Rather, the system 10A allows for the natural flow of high energy vapor phase coolant to the heat exchanger 18 as discussed above, instead of requiring, for example, a pump to force the flow of coolant to a heat exchanger.

[0052] That is, as understood in the art, the circulation (e.g., pumping) of saturated fluids, such as a liquid- vapor refrigerant, can be used to transport thermal energy from the battery 14 to the heat exchanger 18 and vice- versa. In such an arrangement, some liquid phase coolant can be exposed to the heat exchanger 18 along with the vapor phase coolant, so that thermal energy from that portion of the liquid and the vapor can be transferred by the heat exchanger 18 to an external environment, thereby cooling the vapor and that portion of the liquid. However, although the pumping action may facilitate improved heat transfer in the system 10A, such pumping uses energy that can otherwise be used to power other components of the vehicle 1. Hence, the isothermal features of the system 10 are beneficial in that they can avoid the use of a pumping mechanism.

[0053] The heating device 52 is a thermoelectric device, or any other type of appropriate heating device, that is disposed near the lower portion of the insulation member 22. Specifically, the heating device 52 is disposed inside of the insulation member 22 that surrounds the housing 16, and is positioned adjacent to the housing 16 or proximate to the housing 16. In the illustrated embodiment, the heating device 52 is a heating device 52 that is controlled by the controller 34 in response to a signal provided by the sensor 32.

[0054] The sensor 32 detects when a characteristic of the vapor phase coolant is below a threshold, and provides a signal to the controller 34. That is, the sensor 32 detects when a temperature of the vapor phase coolant is below a threshold (e.g., about 18 degrees Celsius) or when the pressure in the chamber 24 is below a threshold (e.g., 400 kPa), and provides a signal to the controller 34. In response, the controller 34 controls the heating device 52 to operate and thus transfer thermal energy to the coolant 26 in the chamber 24. The phase change in the coolant 26 resulting from heating the coolant 26 in that low location in the chamber 24 enables the heat to be transport throughout the liquid coolant 26. When the sensor 32 detects that the temperature and/or pressure of the coolant in the chamber 24 reaches the prescribed threshold, the sensor 32 signals to the controller 34 to NM10-01812 turn off the heating device 52. Thus, the heating device 52 heats the coolant 26 to maintain the target pressure and corresponding target temperature of the coolant 26, and thus the target temperature range of the battery 14. Generally, the controller 34 will turn the fan 37 off when operating the heating device 52. However, the controller 34 can control the fan 37 and the heating device 52 to operate in a cooperative manner to maintain the target pressure and corresponding target temperature of the coolant 26.

[0055] As can be appreciated from the above, by heating the coolant 26 from the bottom of the chamber 24 and thus, from the bottom of the battery 14, there is no need for a pump or mechanical agitation device to heat the coolant 26. Rather, the conversion of the coolant 26 to the vapor phase by the heating and subsequent buoyancy force of the vapor creates sufficient agitation and thermal exposure of the liquid coolant 26 to transfer heat to the battery 14 in a uniform or substantially uniform manner. Furthermore, the saturated properties of the coolant 26 enable uniform or substantially uniform temperature rise within the chamber 24, which avoids the creation of thermal gradients in the battery 14 and, thus minimizes or eliminates performance loss in the battery 14 due to such gradients. That is, since the coolant 26 is in a saturated state, the liquid coolant 26 in the area of the chamber 24 near the heating device 52 will form vapor. In the process of achieving thermal equilibrium, a portion of the vapor will become liquid as the vapor rises through the lower temperature liquid coolant 26. This process releases the heat of vaporization to the static liquid coolant 26 located within the battery assembly.

Accordingly, the entire mass of the saturated liquid coolant 26 can be evenly heated as the target battery operating temperature is achieved.

[0056] In addition, in the system 10A, as discussed above, and in the variations discussed below, a reservoir of the saturated coolant could also be maintained at, for example, a location away from the battery 14 and be pumped into the chamber 24 at a rate controlled by, for example, the controller 34, to rapidly change the temperature of the liquid phase coolant.

[0057] Referring now to Figure 6, a vehicle battery temperature control system 100 in accordance with a third embodiment will now be explained. In view of the similarity between the third embodiment and the first and second embodiments, the parts of the third embodiment that are identical to the parts of the first and second embodiments will be NM 10-01 812 given the same reference numerals as the parts of the first and second embodiments.

Moreover, the descriptions of the parts of the third embodiment that are identical to the parts of the first and second embodiments may be omitted for the sake of brevity. The parts of the third embodiment that differ from the parts of the first and second

embodiments will be indicated with different reference numerals.

[0058] As shown in Figure 6, the vehicle battery temperature control system 100 mainly differs from the vehicle battery temperature control system 10A in that the heating device 52 has been eliminated in the vehicle battery temperature control system 100 and replaced with a valve 154 disposed between a pair of conduits 156 and 158 for selectively supplying heat to a heating device 162 from a heat source. Furthermore, the heating device 162 is coupled to a heat source by a conduit 160. The heat source can be, for example, a heating part of the HVAC system of the vehicle 1. The conduits 156, 158 and 160 can be tubing made of metal, rubber or any other suitable material. Also in the vehicle battery temperature control system 100, an insulation member 122 is provided to substantially enclose the housing 16. The insulation member 122 is similar to the insulation member 22 but configured to accommodate the heating device 162 and the conduits 158 and 160.

[0059] Furthermore, in the vehicle battery temperature control system 100, the heating device 162 is controlled by the controller 34 in response to a signal provided by the sensor 32. The heating device 162 includes a heat exchanger that is disposed in the lower portion of the insulation member 122. Specifically, the heating device 162 is disposed inside of the insulation member 122 that surrounds the housing 16, and is positioned adjacent to the housing 16 or proximate to the housing 16. The heating device 162 functions like a heat pump to move heat from the heat source to the saturated liquid coolant 26. Thus, a heating system including heating device 162 can deliver heat to the saturated liquid coolant 26 without consuming power to energize an electrical heating device. Therefore, less electrical power is consumed for heat transfer to achieve a temperature increase within the chamber 24.

[0060] The sensor 32 detects when a characteristic of the vapor phase coolant is below a threshold, and provides a signal to the controller 34. That is, the sensor 32 detects when a temperature of the vapor phase coolant is below a threshold (e.g., about 18 degrees NM10-0.1812

Celsius) or when the pressure in the chamber 24 is below a threshold (e.g., about 400 kPa), and provides a signal to the controller 34. In response, the controller 34 controls the valve 154 to open to permit heated fluid or air to enter the heat exchanger of the heating device 162 via conduits 156 and 158 to operate and thus transfer thermal energy to the coolant 26 in the chamber 24. The heated air or fluid returns to the heat source via conduit 160. The phase change in the coolant 26 resulting from heating the coolant 26 in that low location in the chamber 24 enables the heat to be transport throughout the liquid coolant 26 to achieve the advantages discussed above with regard to the first embodiment. When the sensor 32 detects that the temperature and/or pressure of the coolant in the chamber 24 reaches the prescribed threshold, the sensor 32 signals to the controller 34 to turn off the heating device 52. Thus, the heating device 52 heats the coolant 26 to maintain the target pressure and corresponding target temperature of the coolant 26, and thus the target temperature range of the battery 14. Generally, the controller 34 will turn the fan 37 off when operating the heating device 52. However, the controller 34 can control the fan 37 and heating device 52 to operate in a cooperative manner to maintain the target pressure and corresponding target temperature of the coolant 26.

[0061] Referring now to Figure 7, a vehicle battery temperature control system 200 in accordance with a fourth embodiment will now be explained. In view of the similarity between the fourth embodiment and the first, second and third embodiments, the parts of the fourth embodiment that are identical to the parts of the first, second and third embodiments will be given the same reference numerals as the parts of the first, second and third embodiments. Moreover, the descriptions of the parts of the fourth embodiment that are identical to the parts of the first, second and third embodiments may be omitted for the sake of brevity. The parts of the fourth embodiment that differ from the parts of the first, second and third embodiments will be indicated with different reference numerals.

[0062] As shown in Figure 7, the vehicle battery temperature control system 200 mainly differs from the vehicle battery temperature control system 100 in that the heating device 162 extend through an insulation member 222, and the heating device 52 is disposed between the heating device 162 and the housing 16. The insulation member 222 is similar to insulation member 22 and substantially enclosing the housing 16. NM10-01812

[0063] Furthermore, the heating device 52 is controlled by the controller 34 in response to a signal provided by the sensor 32 as in the prior embodiment. Likewise, as in the prior embodiment, the heating device 52 is operable to provide a low temperature side and a high temperature side, depending on the polarity of the operating voltage applied to the heating device 52. Accordingly, in the case of heating the coolant 26, the controller 34 controls the application of a voltage to the heating device 52 to operate the heating device 52 so that the high temperature side occurs at the top of the heating device 52 adjacent to the chamber 16 and the low temperature side occurs at the bottom of the heating device 52. In this event, the heating device 52 can operate like a heat pump and draw heat from, for example, the heating device 162. That heat, along with the heat generated by the internal electrical power dissipation in the heating device 52, results in a hot upper surface of the heating device 52 that warms the saturated liquid coolant 26. Accordingly, the heating device 52 can be more efficient at heating the saturated coolant 26 than, for example, the heating device 52 used in the first embodiment.

[0064] The heating device 162, as discussed above, includes a heat exchanger that is disposed in the lower portion of the insulation member 222. Specifically, the heating device 162 is disposed partially inside of the insulation member 222 that surrounds the housing 16, and is positioned adjacent to or proximate to the heating device 52. Naturally, the heating device 162 can be disposed above the heating device 52. Furthermore, the heating device 162, functions like a heat pump to move heat from the heat source to the saturated liquid coolant 26. Thus, a heating system including heating device 162 can deliver more heat to the saturated liquid coolant 26 than a heating system that includes only an electrical heating element such as the heating device 52. Therefore, less electrical power is consumed for the same amount of heat transfer and corresponding temperature increase within the chamber 24.

[0065] The sensor 32 detects when a characteristic of the vapor phase coolant is below a threshold, and provides a signal to the controller 34. That is, the sensor 32 detects when a temperature of the vapor phase coolant is below a threshold (e.g., about 18 degrees Celsius) or when the pressure in the chamber 24 is below a threshold (e.g., about 400 kPa), and provides a signal to the controller 34. In response, the controller 34 activates the heating device 52 as discussed above. Alternatively, or in addition, the controller 34 can NM10-01 812 control the valve 154 to open to permit heated fluid or air to enter the heat exchanger of the heating device 162 via the conduits 156 and 158 to operate and thus transfer thermal energy to the coolant 26 in the chamber 24 as with the heating device 162 discussed above. The heated air or fluid returns to the heat source via the conduit 160. As discussed above, the heating device 162 acts as a heat pump to move heat to the saturated liquid coolant 26. The heating device 52 also acts as a heat pump to facilitate movement of the heat from the heating device 162 to the saturated liquid coolant 26. The phase change in the coolant 26 resulting from heating the coolant 26 in that low location in the chamber 24 enables the heat to be transport throughout the liquid coolant 26 to achieve the advantages discussed above with regard to the first and second embodiments.

[0066] When the sensor 32 detects that the temperature and/or pressure of the coolant in the chamber 24 reaches the prescribed threshold, the sensor 32 signals to the controller 34 to turn off the heating device 52 and the heating device 162 one at a time or at the same time. Thus, the heating device 52 and/or the heating device 162 heat the coolant 26 to maintain the target pressure and corresponding target temperature of the coolant 26, and thus the target temperature range of the battery 14. Generally, the controller 34 will turn the fan 37 off when operating the heating device 52 and/or the heating device 162.

However, the controller 34 can control the fan 37 and the heating device 52 and/or the heating device 162 to operate in a cooperative manner to maintain the target pressure and corresponding target temperature of the coolant 26.

[0067] Referring now to Figure 8, a vehicle battery temperature control system 300 in accordance with a fifth embodiment will now be explained. In view of the similarity between the first through fifth embodiments, the parts of the fifth embodiment that are identical to the parts of the first through fourth embodiments will be given the same reference numerals as the parts of the first through fourth embodiments. Moreover, the descriptions of the parts of the third embodiment that are identical to the parts of the first through fourth embodiments may be omitted for the sake of brevity. The parts of the fifth embodiment that differ from the parts of the first through fourth embodiments will be indicated with different reference numerals.

[0068] As shown in Figure 8, the vehicle battery temperature control system 300 mainly differs from the vehicle battery temperature control system 200 in that the heating NM10-01812 device 162 has been eliminated in the vehicle battery temperature control system 300 and replaced with an air heat exchanger 362. In the vehicle battery temperature control system 300, the heating device 362 is disposed in the lower portion of the insulation member 222. Specifically, the air heat exchanger 362 is disposed inside of the insulation member 222 that surrounds the housing 16, and is exposed to outside of the insulation member 222 as shown. The air heat exchanger 362 is positioned adjacent to or proximate to the heating device 52. The air heat exchanger 362 can include, for example, fins that transfer thermal energy from the heating device 52 to an environment outside the insulation member 222, and receives ambient air and/or forced air (e.g., via a fan) to assist in transferring heat via the heating device 52 to the coolant 26. Like the heating device 162, the heat exchanger 362 functions like a heat pump to move heat from the heat source to the saturated liquid coolant 26. Thus, a heating system including the air heat exchanger 362 can deliver more heat to the saturated liquid coolant 26 than a heating system that includes only an electrical heating element such as heating device 52. Therefore, less electrical power is consumed for the same amount of heat transfer and corresponding temperature increase within the chamber 24.

[0069] The sensor 32 detects when a characteristic of the vapor phase coolant is below a threshold, and provides a signal to the controller 34. That is, the sensor 32 detects when a temperature of the vapor phase coolant is below a threshold (e.g., about 18 degrees Celsius) or when the pressure in the chamber 24 is below a threshold (e.g., about 400 kPa), and provides a signal to the controller 34. In response, the controller 34 activates the heating device 52 as discussed above with regard to heating device 52. The heating device 52 thus acts as a heat pump to facilitate movement of the heat from, for example, the heating device 362 to the saturated liquid coolant 26. The phase change in the coolant 26 resulting from heating the coolant 26 in that low location in the chamber 24 enables the heat to be transport throughout the liquid coolant 26 to achieve the advantages discussed above with regard to the second through fourth embodiments.

[0070] When the sensor 32 detects that the temperature and/or pressure of the coolant in the chamber 24 reaches the prescribed threshold, the sensor 32 signals to the controller 34 to turn off the heating device 52. Thus, the heating device 52 heats the coolant 26 to maintain the target pressure and corresponding target temperature of the coolant 26, and NM 10-01812 thus the target temperature range of the battery 14. Generally, the controller 34 will turn the fan 37 off when operating the heating device 52. However, the controller 34 can control the fan 37 and the heating device 52 to operate in a cooperative manner to maintain the target pressure and corresponding target temperature of the coolant 26.

[0071] Referring now to Figure 9, a vehicle battery temperature control system 400 is illustrated in accordance with a sixth embodiment. Basically, the vehicle battery temperature control system 400 combines the features of the vehicle battery temperature control system 10 of Figure 2 and the vehicle battery temperature control system 10A of Figure 5. Since the vehicle battery temperature control system 400 combines the features of the vehicle battery temperature control systems 10 and 10A into one system, the parts of the sixth embodiment that are identical to the parts of the first and second embodiments will be given the same reference numerals as the parts of the first and second embodiments. Moreover, the descriptions of the parts of the sixth embodiment have been omitted for the sake of brevity.

[0072] Similarly, the features of the vehicle battery temperature control system 10 can be combined with the vehicle battery temperature control systems 100, 200 and 300 as needed and/or desired. In other words, in such a case, the vehicle battery temperature control systems 100, 200 and 300 would include all of the features of the vehicle battery temperature control system 10 of Figure 2. These additional configurations will not be discussed and/or illustrated in further detail for the sake of brevity.

[0073] In understanding the scope of the present invention, the term "comprising" and its derivatives, as used herein, are intended to be open ended terms that specify the presence of the stated features, elements, components, groups, integers, and/or steps, but do not exclude the presence of other unstated features, elements, components, groups, integers and/or steps. The foregoing also applies to words having similar meanings such as the terms, "including", "having" and their derivatives. Also, the terms "part," "section," "portion," "member" or "element" when used in the singular can have the dual meaning of a single part or a plurality of parts. Also as used herein to describe the above

embodiment(s), directional terms such as "frontward", "upward" and "above," as well as any other similar directional terms refer to those directions of a vehicle. Accordingly, these terms, as utilized to describe the present invention should be interpreted relative to a NM 10-01812 vehicle equipped with the vehicle battery temperature control systems described herein. The terms "detect" or "sense," and their variations, as used herein to describe an operation or function carried out by a component, a section, a device or the like includes a component, a section, a device or the like that does not require physical detection, but rather includes determining, measuring, modeling, predicting or computing or the like to carry out the operation or function. The term "configured" as used herein to describe a component, section or part of a device includes hardware and/or software that is constructed and/or programmed to carry out the desired function. The terms of degree such as "substantially", "about" and "approximately" as used herein mean a reasonable amount of deviation of the modified term such that the end result is not significantly changed.

[0074] While only selected embodiments have been chosen to illustrate the present invention, it will be apparent to those skilled in the art from this disclosure that various changes and modifications can be made herein without departing from the scope of the invention as defined in the appended claims. For example, the size, shape, location or orientation of the various components can be changed as needed and/or desired.

Components that are shown directly connected or contacting each other can have intermediate structures disposed between them. The functions of one element can be performed by two, and vice versa. The structures and functions of one embodiment can be adopted in another embodiment. It is not necessary for all advantages to be present in a particular embodiment at the same time. Every feature which is unique from the prior art, alone or in combination with other features, also should be considered a separate description of further inventions by the applicant, including the structural and/or functional concepts embodied by such feature(s). Thus, the foregoing descriptions of the embodiments according to the present invention are provided for illustration only, and not for the purpose of limiting the invention as defined by the appended claims and their equivalents.

Claims

NM10-01812 WHAT IS CLAIMED IS:

1. A vehicle battery temperature control system comprising:

a battery including a heat sink configured to transfer thermal energy with the battery;

a housing including a chamber containing the battery and contain a saturated liquid coolant that substantially immerses the heat sink so that the coolant receives the thermal energy from operation of the battery to cause a phase change of the coolant from a liquid phase to a vapor phase;

a heat exchanger configured to receive vapor phase coolant from the chamber and remove thermal energy from the vapor phase coolant to change the coolant from the vapor phase to the liquid phase, and being further configured to return the liquid phase coolant to the chamber;

a valve operable to selectively fluidly couple the chamber to an air-conditioning refrigeration system to enhance cooling of the coolant in the chamber; and

a sensor operable to detect a characteristic of the coolant and to signal operation of the valve to fluidly couple the chamber to the air-conditioning refrigeration system to increase removal of thermal energy from the coolant based on a relationship between the characteristic of the coolant and a threshold.

2. The vehicle battery temperature control system according to claim 1, wherein

the valve is a vapor collection valve operable to receive the vapor phase coolant from the chamber and coupled to a low pressure side of the air-conditioning refrigeration system.

3. The vehicle battery temperature control system according to claim 1 or 2, wherein

the valve is a return valve configured to provide the liquid phase coolant from a high pressure side of the air-conditioning refrigeration system to the housing. NM10-0.1 812

4. The vehicle battery temperature control system according to claim 3, wherein

the sensor includes a liquid level sensor configured to detect a level of the liquid phase coolant in the housing as the characteristic, and to signal the operation of the valve when the level is sensed as being below the threshold.

5. The vehicle battery temperature control system according to any one of claims 1 to 4, further comprising

a controller configured to operate the valve to fluidly couple the chamber to the air-conditioning refrigeration system when the sensor senses that the characteristic of the coolant is above the threshold.

6. The vehicle battery temperature control system according to any one of claims 1 to 5, wherein

the sensor is operable to detect when the characteristic, which represents a characteristic of the vapor phase coolant, is above the threshold, and is operable to signal the operation of the valve to increase the removal of thermal energy when the

characteristic is above the threshold.

7. The vehicle battery temperature control system according to any one of claim 1 , further

a heating device arranged adjacent the heat sink to enable the heat sink to heat the battery, the heating device being controlled based on a relationship between the characteristic of the vapor phase coolant and a threshold.

8. The vehicle battery temperature control system according to claim 7, wherein

the heating device includes a resistive heater. N 10-01812

9. The vehicle battery temperature control system according to claim 7 or 8, wherein

the heating device includes a second heat exchanger.

10. The vehicle battery temperature control system according to any one of claims 7 to 9, wherein

the heating device further comprises a thermoelectric device configured to transfer thermal energy to the coolant.

11. The vehicle battery temperature control system according to claim 9, wherein

the second heat exchanger is configured to receive heated liquid from a heat source.

12. The vehicle battery temperature control system according to claim 11 , further comprising

a valve that is configured to operate when the characteristic of the vapor phase coolant is above the threshold to provide the heated liquid to the second heat exchanger.

13. The vehicle battery temperature control system according to claim 12, further comprising

a controller configured to control the valve to operate to provide the heated liquid to the second heat exchanger when the characteristic of the coolant is below the threshold.

14. The vehicle battery temperature control system according to any one of claims 7 to 13, further comprising

a fan that is configured to operate when the sensor detects that the characteristic of the vapor phase coolant is above the threshold to increase the removal of thermal energy from the vapor phase coolant by the heat exchanger. NT- O105156

N 10-01812

15. The vehicle battery temperature control system according to any one of claims 1 to 14, wherein

the sensor includes a temperature sensor operable to sense a temperature of the coolant as the characteristic.

16. The vehicle battery temperature control system according to any one of claims 1 to 15, wherein

the sensor includes a pressure sensor operable to sense a pressure in the chamber as the characteristic.

17. The vehicle battery temperature control system according to any one of claims 1 to 16, further comprising

an insulation member configured to substantially enclose the housing.

18. The vehicle battery temperature control system according to any one of claims 1 to 17, wherein

the chamber is configured such that the saturated liquid coolant in the chamber completely immerses the heat sink.

19. The vehicle battery temperature control system according to any one of claims 1 to 18, wherein

the heat exchanger is positioned substantially above a level of the saturated liquid coolant in the chamber.

20. The vehicle battery temperature control system according to any one of claims 1 to 19, wherein

the heat exchanger includes a condenser fluidly coupled to receive the vapor phase coolant, the condenser being operable to remove heat from the vapor phase coolant to create the liquid phase coolant, and being fluidly coupled to return the liquid phase coolant to the chamber. NM 10-01812

21. The vehicle battery temperature control system according to any one of claims 1 to 20, wherein

the saturated liquid coolant includes one of 1,1,1,2-Tetrafluoroethane and 2,3,3,3- Tetrafluoroprop- 1 -ene.

22. A vehicle battery temperature control system comprising:

a battery having a heat sink configured to transfer thermal energy to the battery; a heating device selectively operable to provide thermal energy,

a housing having a chamber formed therein that is configured to receive the battery and contain a saturated liquid coolant that substantially immerses the heat sink so that the coolant receives the thermal energy from the heating device to cause a phase change of the coolant from a liquid phase to a vapor phase to heat the heat sink to enable the heat sink to heat the battery;

a heat exchanger configured to receive vapor phase coolant from the chamber and remove thermal energy from the vapor phase coolant to change the coolant from the vapor phase to the liquid phase, and being further configured to return the liquid phase coolant to the chamber; and

a sensor operable to detect a characteristic of the vapor phase coolant and to signal operation of the heating device to provide the thermal energy based on a relationship between the characteristic of the vapor phase coolant and a threshold.

23. A vehicle battery temperature control method comprising:

operating a battery having a heat sink and disposed in a chamber of a housing containing a saturated liquid coolant into which the battery is immersed, so that the heat sink transfers thermal energy from the battery to the coolant to cause a phase change of the coolant from a liquid phase to a vapor phase;

operating a heat exchanger to receive vapor phase coolant from the chamber and remove thermal energy from the vapor phase coolant to change the coolant from the vapor phase to the liquid phase; NM10-01 812 operating the heat exchanger to return the liquid phase coolant to the chamber; detecting whether a characteristic of the coolant is above a threshold; and fluidly coupling the chamber to an air-conditioning refrigeration system to increase removal of thermal energy from the coolant based on a relationship between the characteristic of the coolant and a threshold.

24. The vehicle battery temperature control method according to claim 23, wherein

the fluidly coupling includes providing the vapor phase coolant from the chamber to a low pressure side of the air-conditioning refrigeration system.

25. The vehicle battery temperature control method according to claim 23 or 24, wherein

the fluidly coupling includes providing the liquid phase coolant from a high pressure side of the air-conditioning refrigeration system to the housing.

26. The vehicle battery temperature control method according to any one of claims 23 to 25, wherein

the detecting includes detecting a level of the liquid phase coolant in the housing as the characteristic; and

the fluidly coupling is performed when the level is detected as being below the threshold.

27. The vehicle battery temperature control method according to any one of claims 23 to 26, wherein

the detecting includes detecting when the characteristic, which represents a characteristic of the vapor phase coolant, is above the threshold.

28. The vehicle battery temperature control method according to any one of claims 23 to 27, further comprising NM10-01.812 operating the heat exchanger to remove thermal energy from the vapor phase coolant to change the coolant from the vapor phase to liquid phase and returns liquid phase coolant to the chamber;

detecting a characteristic of the vapor phase coolant; and

operating a heating device to provide thermal energy based on a relationship between the characteristic of the vapor phase coolant and a threshold, so that the coolant receives the thermal energy from the heating device to cause a phase change of the coolant from the liquid phase to the vapor phase to heat the heat sink which transfers thermal energy to the battery.

29. The vehicle battery temperature control method according to claim 28, wherein

the operating of the heating device includes operating a resistive heater.

30. The vehicle battery temperature control method according to claim 28 or 29, wherein

the operating of the heating device includes operating a second heat exchanger to receive heated liquid from a heat source.

31. The vehicle battery temperature control method according to any one of claims 28 to 30, further comprising

operating a fan when the characteristic of the vapor phase coolant is above the threshold to increase the removal of thermal energy from the vapor phase coolant during the operation of the heat exchanger.

32. The vehicle battery temperature control method according to any one of claims 23 to 31 , wherein

the detecting includes detecting a temperature of the coolant as the characteristic. NM10-01812

33. The vehicle battery temperature control method according to any one of claims 23 to 32, wherein

the detecting includes detecting a pressure in the chamber as the characteristic.

34. A vehicle battery temperature control method comprising:

operating a heat exchanger to receive vapor phase coolant from a chamber that is formed in a housing and configured to contain a battery having a heat sink and a saturated liquid coolant that substantially immerses the heat sink, the operating of the heat exchanger removes thermal energy from the vapor phase coolant to change the coolant from the vapor phase to liquid phase and returns liquid phase coolant to the chamber; detecting a characteristic of the vapor phase coolant; and