VISCOUS HEATER FOR HEAT PUMP SYSTEM

Abstract

An air-conditioning system for a vehicle includes a heat pump system to heat the vehicle. A viscous heater is disposed within the heat pump system to supplement the heat pump system during a heat mode of the air-conditioning system.

Description

FIELD

The present disclosure relates to a heat pump system including a viscous heater for supplementing heat during a heat mode of the heat pump system.

BACKGROUND

The statements in this section merely provide background information related to the present disclosure and may not constitute prior art.

Vehicles having internal combustion engines can use excess heat produced from the engine to heat a passenger cabin of the vehicle. Electric vehicles, which may not have an engine, produce little wasted heat, and, therefore, may need another heating system to heat the passenger cabin. For instance, due to their efficiency and ability to reuse components from conventional air-conditioning system, heat pumps have been utilized in electric vehicles to heat and cool the passenger cabin.

However, heat pumps may not provide enough heating performance at very low temperatures. To overcome such heating deficiency, the capacity of a compressor of the heat pump can be increased. Unfortunately, such an increase may require the use of a non-standard compressor. Thus, requiring another model of a compressor which may have a low manufacturing output and therefore, a higher cost in piece price. Furthermore, a large compressor may not be efficient for moderate conditioning, such as mild heating, which is when the heat pump is used most often.

As another alternative, heat generating devices can be provided to supplement heat to the heat pump. For instance, positive temperature coefficient (PTC) heaters can be used with the heat pump. However, the performance and efficiency of the PTC heater reduces as an inlet temperature increases. The low efficiency of the PTC heater can have a negative effect on the driving range of the electric vehicle. Furthermore, PTC heaters are not typically utilized in a vehicle air conditioning system, and therefore, may be expensive to implement.

SUMMARY

This section provides a general summary of the disclosure and is not a comprehensive disclosure of its full scope or all of its features.

The present disclosure provides for an air-conditioning system for a vehicle. The air-conditioning system can include a heat pump system and a viscous heater disposed within the heat pump system. The viscous heater can be configured to supplement the heat pump system during a heat mode of the air-conditioning system.

Further areas of applicability will become apparent from the description provided herein. The description and specific examples in this summary are intended for purposes of illustration only and are not intended to limit the scope of the present disclosure.

DRAWINGS

The drawings described herein are for illustrative purposes only of selected embodiments and not all possible implementations, and are not intended to limit the scope of the present disclosure.

FIG. 1 is a representative vehicle including an air-conditioning system in accordance with the present disclosure;

FIG. 2 is a schematic view of the air-conditioning system including a heat pump system as a gas injected heat pump and a viscous heater in a first embodiment of the present disclosure;

FIG. 3 is a schematic view of the heat pump system with the viscous heater arranged between an internal condenser and the gas-liquid separator;

FIG. 4 is a schematic view of the viscous heater coupled to a dedicated electric motor which powers the viscous heater;

FIG. 5 is a schematic view of the viscous heater coupled to a compressor motor which powers the viscous heater and the compressor of the heat pump system;

FIG. 6 is a schematic view of the viscous heater coupled to a fan motor which powers the viscous heater and a fan of the heat pump system;

FIGS. 7A, 7B, 7C, and 7D are graphs comparing the AC system of the first embodiment with a gas injection heat pump with no supplemental heat source (GIHP-Baseline) and a gas injection heat pump with PTC heaters (GIHP-PTC);

FIGS. 8A, 8B, 8C, and 8D are graphs comparing NVH proprieties of the AC system of the first embodiment, the GIHP-Baseline, and the GIHP-PTC;

FIG. 9 is a schematic view of the air-conditioning system including the heat pump system as a simple heat pump and the viscous heater in a second embodiment of the present disclosure;

FIG. 10 is a schematic view of the heat pump system as a simple heat pump having multiple viscous heaters arranged therein; and

FIG. 11 is a schematic of the air-conditioning system including the heat pump system as the gas injection heat pump, a coolant loop, and the viscous heater in a third embodiment of the present disclosure.

Corresponding reference numerals indicate corresponding parts throughout the several views of the drawings.

DETAILED DESCRIPTION

Example embodiments will now be described more fully with reference to the accompanying drawings.

With reference to FIGS. 1 and 2, an air-conditioning (AC) system 2 may utilize a heat pump system 4 for heating a passenger cabin of a vehicle. The vehicle can be a hybrid or an electric vehicle, such as a plug-in hybrid electric vehicle (PHEV) or a battery electric vehicle (BEV). The vehicle may also be a conventional vehicle having an engine, where wasted heat from the engine may not be sufficient for heating the passenger cabin. It would be appreciated by one skilled in the art that the heat pump system 4 may perform other air conditioning operations. For example, the heat pump system 4, which may include additional components, may cool the passenger cabin of a vehicle during a cooling mode of the AC system 2.

The heat pump system 4, as shown in FIG. 2, is a gas injection heat pump (GIHP) 6 that includes a compressor 8, an internal condenser 10, a gas-liquid separator 12, an external heat exchanger 14, and an accumulator 16. The AC system 2 also includes a viscous heater 18 as part of the heat pump system 4 to assist with heating the vehicle during the heat mode.

The compressor 8 sucks, compresses, and discharges refrigerant into the GIHP 6. The compressor 8 can include a suction port for drawing vapor refrigerant from the accumulator 16, a gas-injection port for receiving vapor refrigerant from the gas-liquid separator 12 via the viscous heater 18, and a discharge port for discharging compressed refrigerant. The compressor 8 may be an electric compressor that drives a fixed displacement compressor mechanism having a fixed charge capacity by way of an electric motor. Various types of compressors having a fixed displacement compressor mechanism, such as a scroll type compressor and a vane compressor, may be employed. The compressor 8 may also be a variable displacement type compressor.

The compressor 8 is coupled to the internal condenser 10, such that refrigerant flows from the compressor 8 to the internal condenser 10. The internal condenser 10 can be disposed within an air duct housing of the AC system 2 which provides conditioned air to the passenger cabin of the vehicle. The internal condenser 10 heats the air flowing from an evaporator by transferring heat from the refrigerant flowing therein to the air passing through. The air may then enter the passenger cabin of the vehicle via air vents provided within the passenger cabin after being conditioned to a desired temperature by the AC system 2.

Refrigerant from the internal condenser 10 flows to an expansion device 20 which decompresses and expands the refrigerant. From the expansion device 20, the refrigerant flows to the gas-liquid separator 12 which separates the refrigerant into its liquid and vapor forms. The liquid portion of the refrigerant can flow to the external heat exchanger 14 by way of an expansion device 21, which, like the expansion device 20, decompresses and expands the refrigerant. The vapor portion of the refrigerant flows to the compressor 8 by way of the viscous heater 18.

The external heat exchanger 14 may be disposed in a front portion of the vehicle, and exchanges heat between the refrigerant flowing therein and the outside air being blown in by a fan. During the heat mode of the heat pump system 4, the external heat exchanger 14 performs like an evaporator by transferring heat from outside air being blown through to the refrigerant flowing therein, thereby heating the refrigerant.

The refrigerant flows from the external heat exchanger 14 to the accumulator 16 which separates the vapor and liquid forms of the refrigerant. The compressor 8 sucks in vaporous refrigerant from the accumulator 16.

During the heat mode of the AC system 2, the viscous heater 18 heats refrigerant entering the compressor 8 of the GIHP 6. Similar to viscous heaters used in diesel engines, the viscous heater 18 generates heat by shearing viscous fluid provided within a chamber 24 of the viscous heater 18. Specifically, a rotor 26 rotates within the chamber 24 to shear the viscous fluid (FIG. 4). The heat generated is transferred to refrigerant flowing between heat exchanger fins 28 of the viscous heater 18.

The viscous heater 18 can be a variable capacity heater with an ON/OFF state function for controlling the viscous heater 18. For example, the viscous heater may be placed in an OFF state (turned off) when it is not needed, such as during a cooling mode in which the passenger cabin of the vehicle is being cooled. Conversely, during the heat mode, the viscous heater 18 can be in an ON state (turned on). The viscous heater 18 can be controlled by a control unit (C) 25 of the AC system 2 which also controls the heat pump system 4.

The control unit 25 may include a CPU, a RAM, and a ROM. The control unit 25 receives information from various sensors disposed throughout the AC system 2 and from climate control gauges disposed on an instrument panel of the vehicle which can be operated by a user. Based on such information, the control unit 25 controls various components of the AC system 2 to heat and cool air to the desired temperature.

The GIHP 6 heats the passenger cabin of the vehicle by transferring heat from outside of the vehicle to the passenger cabin. As indicated by the arrows in FIG. 2, the compressor 8 sucks vaporous refrigerant from the accumulator 16 and receives heated vaporous refrigerant from the gas-liquid separator 12 via the viscous heater 18. The compressor 8 further compresses the refrigerant and discharges it to the internal condenser 10.

The internal condenser 10 warms the air, which is ultimately provided to the passenger cabin, by transferring heat from the refrigerant flowing therein to air passing through. The refrigerant, which may now be a mixture of vapor and liquid, is decompressed by the expansion device 20 before being separated by the gas-liquid separator 12. From the gas-liquid separator 12, liquid refrigerant flows to the expansion device 21 where it can be decompressed before entering the external heat exchanger 14. By performing like an evaporator, the external heat exchanger 14 heats refrigerant flowing therein by transferring heat from outside air blowing through the external heat exchanger 14 to the refrigerant. Refrigerant from the external heat exchanger 14 may be a mixture of vapor and liquid, and is separated by the accumulator 16.

Vaporous refrigerant from the gas-liquid separator 12 is heated by the viscous heater 18 before being injected into the compressor 8. The refrigerant heated by the viscous heater 18 increases the temperature of the refrigerant discharged by the compressor 8 to the internal condenser 10. Thus, the heating performance of the internal condenser and, ultimately the AC system 2, is improved.

In the event that the viscous heater 18 receives liquid refrigerant with the vapor refrigerant from the gas-liquid separator 12, the viscous heater 18 can heat the liquid refrigerant into a vaporous form. Thus, any liquid refrigerant is prevented from entering the compressor 8.

Although the viscous heater 18 is shown in FIG. 2 as being disposed between the gas-liquid separator 12 and the compressor 8, the viscous heater 18 can be disposed at various suitable positions of the GIHP 6 to heat the refrigerant. For instance, as illustrated in FIG. 3, the viscous heater 18 is provided between the internal condenser 10 and the expansion device 20, thus increasing the amount of vaporous refrigerant entering the gas-liquid separator 12. In another example, the viscous heater 18 can also be provided between the expansion device 20 and the gas-liquid separator 12.

Although only one viscous heater 18 is shown in FIGS. 2 and 3, multiple viscous heaters 18 can be utilized to supplement the heat pump system 4. For example, one viscous heater 18 can be disposed between the gas-liquid separator 12 and the compressor 8 and another can be disposed between the internal condenser 10 and the expansion device 20. In such a configuration, the refrigerant from the internal condenser 10 can be heated and decompressed before entering the gas-liquid separator 12. From the gas-liquid separator 12, the refrigerant is heated again by the other viscous heater 18 before entering the compressor 8. Thus, one or more viscous heaters 18 can be disposed in various suitable locations for supplementing the heat pump system 4.

The viscous heater 18 can be powered by an electric motor using various suitable configurations. For instance, as illustrated in FIG. 4, a dedicated electric motor 30 can be used to power the viscous heater 18. The dedicated electric motor 30 can be coupled to the rotor 26 to rotate the rotor 26, and can be disposed with the viscous heater 18 within the heat pump system 4.

Alternatively, the viscous heater 18 can be integrated with the heat pump system 4 such that the viscous heater 18 is powered by an electric motor already provided in the heat pump system 4. For example, as illustrated in FIG. 5, the viscous heater 18 can be powered by a compressor motor 32 which is an electric motor that powers the compressor 8. As illustrated by the arrows, refrigerant enters the viscous heater 18 where it is heated by viscous fluid sheared by the rotor 26 which is rotated by the compressor motor 32. The refrigerant is then provided to the compressor 8 which then compresses and discharges the refrigerant. The viscous heater 18 can be a variable heater to provide minimal resistance when it is not needed.

In another example shown in FIG. 6, the viscous heater 18 can also be powered by a fan motor 34 which is an electric motor that powers a fan 36. The fan 36 can be arranged near the external heat exchanger 14 to blow outside air through the external heat exchanger 14, and can be a variable output fan. To integrate the viscous heater 18 and the fan 36 with the fan motor 34, one way clutches may be used to ensure proper rotation of the viscous heater 18 and fan 36. The fan 36 can be controlled so that it is not in operation when the viscous heater 18 is in operation (i.e., during the heat mode), thereby allowing the fan motor 34 to be used for both components. Alternatively, when the fan 36 and viscous heater 18 operate at the same time, a torque converter can be used with the fan 36 to vary the torque applied to the fan 36 when the viscous heater 18 is in operation. For instance, the torque converter which may be controlled by the control unit 25, may control the fan 36 so that it spins slower when the fan motor 34 is rotating the viscous heater 18.

In utilizing the GIHP 6 with the viscous heater 18, the heating performance of the AC system 2 of the present disclosure is improved over that of conventional methods. For instance, FIGS. 7A to 7D compares the heating performance of three systems during extremely cold operating conditions: a GIHP system with no supplemental heat source (“GIHP-Baseline” hereinafter); a GIHP system having PTC heaters that heat the air entering the internal condenser (“GIHP-PTC” hereinafter); and the AC system 2 of the present embodiment having the GIHP 6 and the viscous heater 18 (“GIHP-VH” hereinafter).

FIG. 7A provides the relative performance of the systems at extremely cold operating conditions. When the systems are at maximum performance, the GIHP-VH of the present disclosure may perform better than the GIHP-Baseline and the GIHP-PTC, as indicated by the performance bars (Qa). However, the GIHP-VH may consume more power than the other two systems as indicated by the system load bars (L). Although the GIHP-VH consumes more power, the overall energy consumption may be the same or may be lower than the GIHP-Baseline and the GIHP-PTC. Specifically, the GIHP-VH may generate the same amount of heat as the GIHP-Baseline and the GIHP-PTC in a shorter amount of time. Thus, as the vehicle warms up, the control unit 25 of the AC system 2 can switch off the viscous heater 18 to maintain the efficiency of the AC system 2, thereby reducing the power consumption of the system 2.

With reference to FIG. 7B, the coefficient of performance (COP) of the systems is presented. Although, the GIHP-Baseline may have a higher COP than the GIHP-VH and the GIHP-PTC, the GIHP-Baseline may not be satisfying the heating demand of the vehicle at extremely cold operating conditions.

With reference to FIG. 7C, a percent change from the GIHP-Baseline and the GIHP-VH is presented. The increase in performance of the GIHP-VH over the GIHP-Baseline is significantly greater than the loss in COP. The GIHP-VH also provides warmer air at an outlet of the internal condenser than the GIHP-Baseline (shown as “% delta Air Temp” in FIG. 7C).

With respect to the GIHP-PTC, the GIHP-VH has similar performance and power consumption as the GIHP-PTC. However, as the air temperature at an inlet of the internal condenser increases, the performance of the GIHP-VH system may increase rapidly over the GIHP-PTC. Specifically, the GIHP-PTC heats the air entering the internal condenser. As an inlet temperature of the internal condenser increases, the performance and efficiency of the PTC heater decreases.

With reference to FIG. 7D, the percent change from the GIHP-PTC to the GIHP-VH is presented. The performance and the COP of the GIHP-VH are improved over the GIHP-PTC. In addition, the GIHP-VH provides warmer air at an outlet of the internal condenser than the GIHP-PTC (shown as “% delta Air Temp” in FIG. 7D).

In addition to improved performance, the AC system 2 has improved noise-vibration-harshness (NVH) qualities when compared to the GIHP-Baseline and GIHP-PTC. The speed of a compressor is closely related to the NVH qualities of the compressor. In a situation in which the same or substantially the same level of performance is required in each of the system, the GIHP-VH may be the preferred system.

For instance, with reference to FIGS. 8A-8D the relative performance of the systems at extremely cold operating conditions is presented. The GIHP-Baseline has about the same level of performance as the GIHP-VH and the GIHP PTC (as indicated by bar “Qa”). However, the compressor of the GIHP-Baseline may have to operate at about 8600 rpm to achieve substantially the same level of performance as the GIHP-VH and the GIHP-PTC, which have compressors that operate at about 3000 rpm. Accordingly, the GIHP-Baseline has a higher power consumption than the GIHP-VH and the GIHP-PTC (as indicated by bar “L”). Thus, the NVH qualities of the GIHP-VH is greatly reduced over the NVH qualities of the GIHP-Baseline.

With reference to FIG. 8C, a percent change from the GIHP-Baseline and the GIHP-VH is presented. By having a compressor speed of 8600 rpm, the GIHP-Baseline has similar performance levels as the GIHP-VH (FIGS. 8A and 8B). However, the heating performance, COP, air temperature, and compressor speed of the GIHP-VH are an improvement over the GIHP-Baseline.

In regards to the GIHP-PTC, the GIHP-VH has about the same or similar level of performance as the GIHP-PTC. However, as shown in FIG. 8D, the COP of GIHP-VH is an improvement over the GIHP-PTC at some cost to performance. As stated above, the GIHP-VH may generate the same amount of heat as the GIHP-PTC in shorter amount of time. Therefore, once the heating requirements are met by the system, the COP may be more important than heating performance.

The AC system 2 of the present disclosure may include a normal or standard size compressor, thereby employing standard heat pump components readily available. With a standard size compressor, the GIHP-VH has improved performance capabilities over the GIHP-Baseline. The GIHP-VH may also use a smaller compressor than, for example, the GIHP-Baseline. With the smaller compressor, the GIHP-VH may have the same performance as the GIHP-Baseline.

In utilizing the viscous heater 18 as a supplemental heat source, the AC system 2 may be less complex to package into the vehicle than the use of PTC heaters. For instance, PTC heaters are typically installed in the air-duct housing which can be a standard component. Packaging space provided in the air duct housing may be constrained, thereby making it difficult to incorporate additional components like PTC heaters. The viscous heater 18 can be integrated with heat pump components, like the compressor 8, or installed at another position under the hood of the vehicle. Thus, the AC system 2 is able to employ standard heat pump components and achieve better heat performance by employing the viscous heater 18 with the heat pump system 4.

In the first embodiment of the present disclosure, the heat pump system 4 of the AC system 2 is provided as the GIHP 6. The GIHP 6 typically performs better than other heat pumps; however, the GIHP 6 can be more complex, costly, and can be difficult to package. As an alternative to the GIHP 6, the heat pump system 4 can be a simple heat pump 40, as shown in FIG. 9 in a second embodiment of the present disclosure. The simple heat pump 40, which is less complex and less expensive, includes most of the components of the GIHP 6 except for the gas-liquid separator 12 and the expansion device 20. The simple heat pump 40 is configured to include the compressor 8, the internal condenser 10, the expansion device 21, the external heat exchanger 14, and the accumulator 16, which all function in the same manner as in the first embodiment.

Without the gas-liquid separator 12, the compressor 8 of the simple heat pump 40 draws vapor refrigerant from the accumulator 16 via the suction port and discharges compressed refrigerant to the internal condenser 10 via the discharge port. Accordingly, the compressor 8 does not receive additional vaporous refrigerant which is provided in the GIHP 6 by way of the gas-liquid separator 12. Instead, refrigerant from the internal condenser 10, which may be in both liquid and vapor forms, flows to the expansion device 21 and then to the external heat exchanger 14.

Similar to the first embodiment, the AC system 2 of the second embodiment includes the viscous heater 18 which can be arranged between compressor 8 and the internal condenser 10. According to such configuration, the simple heat pump 40 heats the passenger cabin of the vehicle by transferring heat from outside air to the passenger cabin. Specifically, as indicated by the arrows in FIG. 9, the compressor 8 sucks vaporous refrigerant from the accumulator 16 and discharges it to the viscous heater 18 which heats the refrigerant and provides it to the internal condenser 10. As previously described, the internal condenser 10 transfers heat from the refrigerant flowing therein to the air blowing through. The refrigerant, which may now include both liquid and vapor forms, flows to the external heat exchanger 14 by way of the expansion device 21. The external heat exchanger 14 heats the refrigerant by transferring heat from outside air blowing through to the refrigerant flowing therein. From the external heat exchanger 14, the refrigerant flows to the accumulator 16 which separates the refrigerant into its liquid and vapor forms. The compressor 8 sucks the vapor refrigerant which is then again compressed and discharged into the simple heat pump 40.

By arranging the viscous heater 18 between the compressor 8 and the internal condenser 10, the viscous heater 18 heats the refrigerant from the compressor 8 before providing it to the internal condenser 10, thereby increasing the heating performance of the internal condenser 10 and, ultimately, the AC system 2. Therefore, the simple heat pump 40 having the viscous heater 18 improves the performance of the AC system 2 by providing additional heat during the heat mode.

The AC system 2 of the first embodiment, which includes the GIHP 6 and the viscous heater 18, may achieve a higher performance than the AC system 2 of the second embodiment, which includes the simple heat pump 40 and the viscous heater 18. Based on the configuration of the AC system 2 of the first embodiment, the GIHP 6 has a gas injection flow path from the gas-liquid separator 12 to the compressor 8, which, as described above, is not included in the simple heat pump 40. The gas injection flow path increases performance of the heat pump system 4 by adding high pressure, high enthalpy refrigerant to the compressor 8, thereby increasing the pressure and enthalpy of the refrigerant discharged by the compressor 8. By heating vaporous refrigerant from the gas-liquid separator 12, the enthalpy of the vaporous refrigerant leaving the viscous heater 18 increases the effect the vaporous refrigerant has on the compressor 8. Accordingly, the AC system 2 of the first embodiment, which has the GIHP 6 with the viscous heater 18, may perform better than the AC system 2 of the second embodiment having the simple heat pump 40 with the viscous heater 18.

Although the AC system 2 of the first embodiment may have a higher performance than the second embodiment, the simple heat pump 40 with the viscous heater 18 can be less complex and costly than the GIHP 6 with the viscous heater 18. In addition, the viscous heater 18 can provide the same or substantially the same level of supplemental heat performance for the simple heat pump 40, as in the GIHP 6, when it is arranged at the same or similar position along the heat pump system 4. For instance, if the viscous heater 18 is arranged between the compressor 8 and the internal condenser 10 for both the GIHP 6 and the simple heat pump 40, the viscous heater 18 would have the same or substantially the same supplemental effect on the heat pump system 4. Therefore, by employing the simple heat pump 40 with the viscous heater 18, the AC system 2 of the second embodiment provides improved heating performance during the heat mode with less complexity and cost.

Furthermore, the AC system 2 of the second embodiment may also employ standard heat pump components which are readily available, along with the viscous heater 18, which can be easily integrated with the simple heat pump 40.

Similar to the first embodiment, one or more viscous heater 18 can be disposed at various suitable positions within the simple heat pump 40 to heat the refrigerant. For example, as shown in FIG. 10, the viscous heater 18 can be provided between the compressor 8 and the accumulator 16, thereby heating vaporous refrigerant from the accumulator 16 before it is provided to the compressor 8. In addition, more than one viscous heater 18 can be disposed to supplement the simple heat pump 40 during the heat mode (FIG. 10).

Certain vehicles, such as the PHEV, may use heat from an engine or a heat pump to heat the vehicle. Such vehicles may utilize the heat pump to heat coolant. The coolant can then be used to heat the vehicle by way of a coolant loop. During cold temperatures, another heat source can be used to supplement the heating performance of the heat pump. For instance, in a third embodiment of the present disclosure, as shown in FIG. 11, the AC system 2 can be configured to have the heat pump system 4 wherein the internal condenser 10 is replaced with a water-to-refrigerant heat exchanger 50. The water-to-refrigerant heat exchanger 50 is coupled to a coolant loop 52 that includes a heater core 54, a pump 56, and the viscous heater 18. Although the heat pump system 4 is shown as a GIHP 6, the heat pump system 4 may also be, for example, the simple heat pump 40.

The heater core 54 heats the passenger cabin of the vehicle by transferring heat from hot coolant flowing therein to air passing though the heater core 54. The coolant, which may now be cold, flows to the viscous heater 18 by way of the pump 56. The viscous heater 18 warms the coolant before discharging it to the water-to-refrigerant heat exchanger 50. The water-to-refrigerant heat exchanger 50 further warms the coolant flowing therein with the refrigerant from the heat pump system 4. Specifically, the water-to-refrigerant heat exchanger 50 transfers heat from the refrigerant to the coolant which then flows to the heater core 54. The refrigerant leaving the water-to-refrigerant heat exchanger 50 is heated by the heat pump system 4.

Although the viscous heater 18 is provided within the coolant loop 52 in FIG. 11, the viscous heater 18 can be provided within the heat pump system 4. For instance, the viscous heater 18 can be disposed between the gas-liquid separator 12 and the compressor 8, thereby allowing the viscous heater 18 to supplement the AC system which has a coolant loop. Furthermore, in addition to the viscous heater 18 provided within the coolant loop 52, another viscous heater can be disposed between within the heat pump system 4. For example, another viscous heater can be disposed between the gas-liquid separator 12 and the compressor 8.

By having the viscous heater 18 disposed before the water-to-refrigerant heat exchanger 50, the viscous heater 18 preheats the coolant going into the water-to-refrigerant heat exchanger 50. Accordingly, the refrigerant leaving the water-to-refrigerant heat exchanger 50 may have a higher temperature than the refrigerant leaving the water-to-refrigerant heat exchanger 50 when the viscous heater 18 is not provided to preheat the coolant. As a result, the external heat exchanger 14, which can limit the performance of the AC system 2, receives warmer refrigerant at a higher flow rate, thereby increasing the performance of the heat pump system 4.

Furthermore, the third embodiment may provide for a more flexible design than the first and second embodiments. For instance, if conventional hybrid and electric vehicles have the same heat pump system 4, the heat pump system 4 can still be supplemented by disposing the viscous heater 18 along the coolant loop 52 instead of the heat pump system 4.

Although the use of the viscous heater 18 with the heat pump system 4 is described in relation to the AC system 2 of the vehicle, it should be understood that the viscous heater 18 and the heat pump system 4 can be used in other thermal control operations. For example, the viscous heater 18 can be used with the heat pump system 4 and/or coolant loop 52 to control the temperature of a battery pack used in hybrid vehicles and electric vehicles.

The foregoing description of the embodiments has been provided for purposes of illustration and description. It is not intended to be exhaustive or to limit the disclosure. Individual elements or features of a particular embodiment are generally not limited to that particular embodiment, but, where applicable, are interchangeable and can be used in a selected embodiment, even if not specifically shown or described. The same may also be varied in many ways. Such variations are not to be regarded as a departure from the disclosure, and all such modifications are intended to be included within the scope of the disclosure.

Example embodiments are provided so that this disclosure will be thorough, and will fully convey the scope to those who are skilled in the art. Numerous specific details are set forth such as examples of specific components, devices, and methods, to provide a thorough understanding of embodiments of the present disclosure. It will be apparent to those skilled in the art that specific details need not be employed, that example embodiments may be embodied in many different forms and that neither should be construed to limit the scope of the disclosure. In some example embodiments, well-known processes, well-known device structures, and well-known technologies are not described in detail.

The terminology used herein is for the purpose of describing particular example embodiments only and is not intended to be limiting. As used herein, the singular forms “a,” “an,” and “the” may be intended to include the plural forms as well, unless the context clearly indicates otherwise. The terms “comprises,” “comprising,” “including,” and “having,” are inclusive and therefore specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof. The method steps, processes, and operations described herein are not to be construed as necessarily requiring their performance in the particular order discussed or illustrated, unless specifically identified as an order of performance. It is also to be understood that additional or alternative steps may be employed.

When an element or layer is referred to as being “on,” “engaged to,” “connected to,” or “coupled to” another element or layer, it may be directly on, engaged, connected or coupled to the other element or layer, or intervening elements or layers may be present. In contrast, when an element is referred to as being “directly on,” “directly engaged to,” “directly connected to,” or “directly coupled to” another element or layer, there may be no intervening elements or layers present. Other words used to describe the relationship between elements should be interpreted in a like fashion (e.g., “between” versus “directly between,” “adjacent” versus “directly adjacent,” etc.). As used herein, the term “and/or” includes any and all combinations of one or more of the associated listed items.

Claims

1. An air-conditioning system for a vehicle comprising:

a heat pump system conditioning air for a passenger cabin of a vehicle; and

a viscous heater disposed within the heat pump system, wherein the viscous heater receives and heats refrigerant flowing in the heat pump system.

2. The air-conditioning system of claim 1, wherein a plurality of the viscous heaters are disposed within the heat pump system.

3. The air-conditioning system of claim 1, wherein the viscous heater includes an electric motor.

4. The air-conditioning system of claim 1 further comprising:

a coolant loop coupled to the heat pump system for conditioning the air for the passenger cabin of the vehicle.

5. The air-conditioning system of claim 4 further comprising:

another viscous heater disposed along the coolant loop for heating coolant flowing in the coolant loop.

6. An air-conditioning system for a vehicle comprising:

a heat pump system including a compressor compressing refrigerant flowing therein, an internal condenser communicating with the compressor for receiving the refrigerant and exchanging heat between the refrigerant flowing therein and air blowing through the internal condenser, an external heat exchanger communicating with the internal condenser for receiving the refrigerant and exchanging heat between the refrigerant flowing therein and air blowing through the external heat exchanger, and an accumulator communicating with the external heat exchanger for receiving the refrigerant and communicating with the compressor for providing the refrigerant; and

a viscous heater disposed within the heat pump system, the viscous heater receiving and heating the refrigerant flowing in the heat pump system.

7. The air-conditioning system of claim 6 wherein the heat pump system further comprises an electric motor that powers the compressor and the viscous heater.

8. The air-conditioning system of claim 6, wherein a plurality of the viscous heaters are disposed within the heat pump system.

9. The air conditioning system of claim 6 wherein the heat pump system further comprises:

a fan that blows air through the external heat exchanger; and

an electric motor that powers the fan and the viscous heater.

10. The air-conditioning system of claim 6, wherein the heat pump system further includes:

a gas-liquid separator that communicates with the internal condenser to receive the refrigerant, the gas liquid separator separates the refrigerant into vapor and liquid forms, and the gas-liquid separator further communicates with the compressor and the external heat exchanger to substantially provide the vapor form of the refrigerant to the compressor and the liquid form of the refrigerant to the external heat exchanger.

11. The air-conditioning system of claim 10, wherein the viscous heater is disposed between the compressor and the gas-liquid separator, the viscous heater communicates with the gas-liquid separator to receive the vapor form of the refrigerant and communicates with the compressor to provide the vapor form of the refrigerant after heating the refrigerant received from the gas-liquid separator.

12. The air-conditioning system of claim 6, wherein the viscous heater includes an electric motor.

13. An air-conditioning system for heating and cooling a vehicle comprising:

a heat pump system including a compressor compressing refrigerant flowing therein, a water-to-refrigerant heat exchanger communicating with the compressor for receiving the refrigerant and exchanging heat between the refrigerant and coolant, an external heat exchanger communicating with the water-to-refrigerant heat exchanger for receiving the refrigerant and exchanging heat between the refrigerant flowing therein and air blowing through the external heat exchanger, and an accumulator communicating with the external heat exchanger for receiving the refrigerant and communicating with the compressor for providing the refrigerant;

a coolant loop communicating with the water-to-refrigerant heat exchanger of the heat pump system for providing the coolant; and

a viscous heater providing supplemental heat.

14. The air-conditioning system of claim 13, wherein the viscous heater is disposed within the heat pump system to heat the refrigerant flowing in the heat pump system.

15. The air-conditioning system of claim 13 wherein the viscous heater is disposed within the coolant loop to heat the coolant flowing in the coolant loop.

16. The air-conditioning system of claim 15, further comprising:

at least one other viscous heater disposed within the heat pump system for receiving and heating the refrigerant flowing in the heat pump system.

17. The air-conditioning system of claim 13, wherein the viscous heater further comprises an electric motor.

18. The air-conditioning system of claim 13, wherein

the coolant loop includes a heater core that exchanges heat between the coolant flowing therein and air blowing through the heater core, and a pump that communicates with the heater core for pushing the coolant through the coolant loop, and

the viscous heater is disposed between the pump of the coolant loop and the water-to-refrigerant heat exchanger of the heat pump system, the viscous heater communicates with the pump to receive the coolant and communicates with the water-to-refrigerant heat exchanger to provide the coolant after heating the coolant received from the pump.