Bus R744 refrigerant low-environment-temperature heat pump system

Abstract

A high-pressure side of a compressor is connected with a first port of a first three-way valve, a second port of the first three-way valve is connected with an external air cooling heat exchanger, and a third port of the first three-way valve is connected with a second three-way valve; the outside-vehicle air cooling heat exchanger is connected with a heating expansion valve, and the other end of the heating expansion valve is connected to a backheating heat exchanger; first one-way valves are arranged at two ends of the heating expansion valve in parallel; the other end of the in-vehicle air cooling heat exchanger is connected with a refrigeration expansion valve; two ends of the refrigeration expansion valve are connected in parallel with a second one-way valve; the first end of the in-vehicle water-side heat exchanger is connected with a third port of the second three-way valve, the second end and the third end of the in-vehicle water-side heat exchanger are connected with the in-vehicle water inlet and the in-vehicle water outlet respectively, and the fourth end of the in-vehicle water-side heat exchanger is connected with the in-vehicle water-side expansion valve. On one hand, the heat exchange efficiency can be improved, the boundary size of the evaporation box is reduced, and on the other hand, the structure is easy to install, good in universality and suitable for installation and arrangement requirements of different vehicle types.

Description

Technical Field

[0001] This utility model pertains to vehicle thermal management systems, specifically to a low ambient temperature heat pump system for buses using R744 refrigerant. Background Technology

[0002] Low-ambient-temperature heat pump systems for buses using R744 refrigerant typically employ a four-way valve for switching between cooling and heating modes due to the high operating pressure. However, four-way valves suffer from low reliability and a high failure rate. Therefore, it is necessary to use a combination of several solenoid valves for flow path switching. Existing products generally use combinations of three or more three-way or two-way valves for mode switching. Since electric three-way or two-way valves are high-precision and high-cost components, they suffer from high cost and high failure rate. Furthermore, the increased number of control components correspondingly raises the requirements for control reliability.

[0003] In addition, when using R744 refrigerant systems for low-temperature heating, especially when operating at low ambient temperatures below -25°C, the compressor discharge temperature will be too high and will exceed the discharge temperature protection limit. Therefore, the compressor speed is usually reduced to lower the discharge temperature. During this process, the compressor speed will be reduced, which will decrease the low-temperature heating performance and energy efficiency. Utility Model Content

[0004] The technical problem to be solved by this utility model is to provide a low ambient temperature heat pump system for buses using R744 refrigerant, which addresses the problems of high failure rate, low reliability and poor heating performance of R744 heat pump products on the market.

[0005] To solve the above problems, this utility model is achieved through the following technical solution:

[0006] A low ambient temperature heat pump system for R744 refrigerant in buses includes a compressor, the high-pressure side of which is connected to the first port of a first three-way valve, the second port of which is connected to an external air-cooled heat exchanger, and the third port of which is connected to a second three-way valve.

[0007] The external air-cooled heat exchanger is connected to a heating expansion valve, and the other end of the heating expansion valve is connected to a regenerative heat exchanger; a first check valve is connected in parallel at both ends of the heating expansion valve.

[0008] The first end of the regenerating heat exchanger is connected to the heating expansion valve, the second end of the regenerating heat exchanger is connected to the gas-liquid separator, the third end of the regenerating heat exchanger is connected to the drying filter, and the fourth end of the regenerating heat exchanger is connected to the low-pressure side of the compressor.

[0009] The first port of the second three-way valve is connected to the third port of the first three-way valve. The second port of the second three-way valve is connected to the gas-liquid separator. The third port of the second three-way valve is connected to the in-vehicle air-cooled heat exchanger and the in-vehicle water-side heat exchanger, respectively. The other end of the in-vehicle air-cooled heat exchanger is connected to the refrigeration expansion valve. The two ends of the refrigeration expansion valve are connected in parallel with a second one-way valve. The first end of the in-vehicle water-side heat exchanger is connected to the third port of the second three-way valve. The second and third ends of the in-vehicle water-side heat exchanger are connected to the in-vehicle water inlet and outlet, respectively. The fourth end of the in-vehicle water-side heat exchanger is connected to the in-vehicle water-side expansion valve.

[0010] The in-vehicle water-side heat exchanger is connected in parallel with the battery water-side heat exchanger. The first end of the battery water-side heat exchanger is connected to the second port of the second three-way valve. The second and third ends of the battery water-side heat exchanger are connected to the battery inlet and outlet, respectively. The fourth end of the battery water-side heat exchanger is connected to the battery cooling expansion valve.

[0011] An external air-cooled heat exchanger is equipped with an external fan; an internal air-cooled heat exchanger is equipped with an internal fan.

[0012] A bypass expansion valve is installed in parallel outside the gas-liquid separator, and the bypass expansion valve is connected in parallel between the gas-liquid separator and the third end of the regenerative heat exchanger.

[0013] Compared with the prior art, the present invention has the following beneficial effects:

[0014] 1. This utility model has the functions of air conditioning cooling, ambient temperature heating down to -25℃, battery liquid cooling, and battery waste heat recovery;

[0015] 2. This utility model uses two electric three-way valves to switch between cooling and heating modes in the main circulation loop;

[0016] 3. This utility model is equipped with a liquid pipe bypass circuit, with the inlet of the bypass electronic expansion valve connected in parallel to the high-pressure liquid pipe and the outlet connected to the gas separator inlet pipe.

[0017] Therefore, on the one hand, it can improve heat exchange efficiency and reduce the boundary size of the evaporator box; on the other hand, this structure is simple to install, has good versatility, and is suitable for the installation and layout needs of different vehicle models. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of the refrigeration operation state of this utility model;

[0019] Figure 2 This is a schematic diagram of the heating operation state of this utility model;

[0020] Figure 3 This is a schematic diagram of the ultra-low temperature heating operation of this utility model. Detailed Implementation

[0021] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the protection scope of the present utility model.

[0022] In the description of this utility model, it should be understood that the terms "upper", "lower", "front", "rear", "left", "right", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this utility model and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this utility model.

[0023] like Figure 1 As shown, a low ambient temperature heat pump system for R744 refrigerant in a bus includes a compressor 1. The high-pressure side of the compressor 1 is connected to the first port of a first three-way valve 2. The second port of the first three-way valve 2 is connected to an external air-cooled heat exchanger 3. The third port of the first three-way valve 2 is connected to a second three-way valve 10.

[0024] The external air-cooled heat exchanger 3 is connected to the heating expansion valve 6, and the other end of the heating expansion valve 6 is connected to the regenerative heat exchanger 7; a first one-way valve 5 is provided in parallel at both ends of the heating expansion valve 6.

[0025] The first end of the regenerating heat exchanger 7 is connected to the heating expansion valve 6, the second end of the regenerating heat exchanger 7 is connected to the gas-liquid separator 8, the third end of the regenerating heat exchanger 7 is connected to the drying filter 15, and the fourth end of the regenerating heat exchanger 7 is connected to the low-pressure side of the compressor 1.

[0026] The first port of the second three-way valve 10 is connected to the third port of the first three-way valve 2. The second port of the second three-way valve 10 is connected to the gas-liquid separator 8. The third port of the second three-way valve 10 is connected to the in-vehicle air-cooled heat exchanger 13 and the in-vehicle water-side heat exchanger 16, respectively. The other end of the in-vehicle air-cooled heat exchanger 13 is connected to the refrigeration expansion valve 12. The two ends of the refrigeration expansion valve 12 are connected in parallel with the second one-way valve 14. The first end of the in-vehicle water-side heat exchanger 16 is connected to the third port of the second three-way valve 10. The second and third ends of the in-vehicle water-side heat exchanger 16 are connected to the in-vehicle water inlet and outlet, respectively. The fourth end of the in-vehicle water-side heat exchanger 16 is connected to the in-vehicle water-side expansion valve 17.

[0027] The in-vehicle water-side heat exchanger 16 is connected in parallel to a battery water-side heat exchanger 19. The first end of the battery water-side heat exchanger 19 is connected to the second port of the second three-way valve 10. The second and third ends of the battery water-side heat exchanger 19 are connected to the battery inlet and outlet, respectively. The fourth end of the battery water-side heat exchanger 19 is connected to the battery cooling expansion valve 18. It should be noted that the battery water-side heat exchanger 19 and the battery cooling expansion valve 18 constitute a battery cooling circulation loop.

[0028] Furthermore, an external air-cooled heat exchanger 3 is equipped with an external fan 4; and an internal air-cooled heat exchanger 13 is equipped with an internal fan 11.

[0029] Furthermore, a bypass expansion valve 9 is installed in parallel outside the gas-liquid separator 8. The bypass expansion valve 9 is connected in parallel between the gas-liquid separator 8 and the third end of the regenerating heat exchanger 7. It should be noted that the bypass electronic expansion valve 9 and the connecting pipeline form a liquid pipe bypass circuit.

[0030] The working principle of this utility model is as follows:

[0031] During refrigeration operation, the first three-way valve 2 and the second three-way valve 10 of the main circulation loop are not energized. Refrigerant is discharged from compressor 1, passing sequentially through the first three-way valve 2, the external heat exchanger 3, the first one-way valve 5, the regenerative heat exchanger 7, the dryer filter 15, the refrigeration expansion valve 12, the internal air-cooled heat exchanger 13, the second three-way valve 10, the gas-liquid separator 8, and the regenerative heat exchanger 7, before returning to compressor 1. This circulation loop is responsible for cooling the bus passenger compartment. Simultaneously, when the internal water-side expansion valve 17 opens, a portion of the refrigerant is diverted from the outlet of the dryer filter 15 to the internal water-side heat exchanger 16, then through the second three-way valve 10, the gas-liquid separator 8, and the regenerative heat exchanger 7, before returning to compressor 1. This parallel loop is responsible for cooling the bus driver's compartment. At the same time, when the battery cooling expansion valve 18 is opened, a portion of the refrigerant is diverted from the outlet of the dryer filter 15 to the battery water-side heat exchanger 19, and then passes through the gas-liquid separator 8 and the regenerative heat exchanger 7 in sequence before returning to the compressor 1. This parallel circuit is responsible for cooling the battery.

[0032] During heating operation, the first three-way valve 2 and the second three-way valve 10 of the main circulation loop are energized. Refrigerant is discharged from compressor 1 and sequentially passes through the second three-way valve 10, the in-vehicle air-cooled heat exchanger 13, the second one-way valve 14, the dryer filter 15, the regenerative heat exchanger 7, the heating expansion valve 6, the external air-cooled heat exchanger 3, the first three-way valve 2, the gas-liquid separator 8, and the regenerative heat exchanger 7 before returning to compressor 1. This circulation loop is responsible for heating the bus passenger compartment. Simultaneously, when the in-vehicle water-side expansion valve 17 is fully open, a portion of the refrigerant is diverted from the outlet of the first three-way valve 2 to the in-vehicle water-side heat exchanger 16, then passes through the in-vehicle water-side expansion valve 17, merges with the refrigerant in the main circulation loop, and returns to compressor 1. This parallel loop is responsible for heating the bus driver's compartment. At the same time, when the battery cooling expansion valve 18 is opened, a portion of the refrigerant from the inlet of the dryer filter 15 is diverted to the battery water-side heat exchanger 19, and then passes through the gas-liquid separator 8 and the heat recovery heat exchanger 7 in sequence before returning to the compressor 1. This parallel circuit is responsible for cooling the battery and, at the same time, increases the heating performance and energy efficiency by recovering the heat dissipated by the battery.

[0033] When operating at ultra-low temperatures, the compressor discharge temperature limit T1 is set. When the actual discharge temperature is greater than the compressor discharge temperature limit T1, the bypass electronic expansion valve 9 is opened, and the valve opening is controlled according to T1 to keep the actual discharge temperature below T1.

[0034] Therefore, the R744 refrigerant bus thermal management system of this utility model has functions of air conditioning cooling, ambient temperature heating down to -25℃, battery liquid cooling, and battery waste heat recovery.

[0035] The above description is only a preferred embodiment of the present utility model. It should be noted that those skilled in the art can make several changes and improvements without departing from the overall concept of the present utility model, and these should also be considered within the protection scope of the present utility model.

Claims

1. A low-ambient-temperature heat pump system for buses using R744 refrigerant, characterized in that: Includes a compressor (1), the high-pressure side of the compressor (1) is connected to the first port of the first three-way valve (2), the second port of the first three-way valve (2) is connected to the external air-cooled heat exchanger (3), and the third port of the first three-way valve (2) is connected to the second three-way valve (10). The external air-cooled heat exchanger (3) is connected to the heating expansion valve (6), and the other end of the heating expansion valve (6) is connected to the regenerative heat exchanger (7); a first check valve (5) is provided in parallel at both ends of the heating expansion valve (6). The first end of the regenerating heat exchanger (7) is connected to the heating expansion valve (6), the second end of the regenerating heat exchanger (7) is connected to the gas-liquid separator (8), the third end of the regenerating heat exchanger (7) is connected to the drying filter (15), and the fourth end of the regenerating heat exchanger (7) is connected to the low-pressure side of the compressor (1). The first port of the second three-way valve (10) is connected to the third port of the first three-way valve (2), the second port of the second three-way valve (10) is connected to the gas-liquid separator (8), and the third port of the second three-way valve (10) is connected to the in-vehicle air-cooled heat exchanger (13) and the in-vehicle water-side heat exchanger (16), respectively; wherein, the other end of the in-vehicle air-cooled heat exchanger (13) is connected to the refrigeration expansion valve (12), and the two ends of the refrigeration expansion valve (12) are connected in parallel with the second one-way valve (14); the first end of the in-vehicle water-side heat exchanger (16) is connected to the third port of the second three-way valve (10), the second and third ends of the in-vehicle water-side heat exchanger (16) are connected to the in-vehicle water inlet and water outlet, respectively, and the fourth end of the in-vehicle water-side heat exchanger (16) is connected to the in-vehicle water-side expansion valve (17). The in-vehicle water-side heat exchanger (16) is connected in parallel with the battery water-side heat exchanger (19). The first end of the battery water-side heat exchanger (19) is connected to the second port of the second three-way valve (10). The second and third ends of the battery water-side heat exchanger (19) are connected to the battery inlet and outlet, respectively. The fourth end of the battery water-side heat exchanger (19) is connected to the battery cooling expansion valve (18).

2. The low-ambient-temperature heat pump system for buses using R744 refrigerant according to claim 1, characterized in that: An external air-cooled heat exchanger (3) is equipped with an external fan (4); an internal air-cooled heat exchanger (13) is equipped with an internal fan (11).

3. A low-ambient-temperature heat pump system for buses using R744 refrigerant according to claim 1, characterized in that: A bypass expansion valve (9) is installed in parallel outside the gas-liquid separator (8), and the bypass expansion valve (9) is connected in parallel between the gas-liquid separator (8) and the third end of the regenerating heat exchanger (7).

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