Vehicle air conditioning device

Abstract

Provided is a vehicle air conditioning device. An engine, a heater, and a heater core are connected by a pipe. In a case where a travel mode is an HEV travel mode or an engine-only travel mode, a flow path constituted by the pipe is formed, and the heater core is heated by cooling water heated by the engine. In a case where the travel mode is an EV travel mode, a flow path constituted by the pipe is formed, and the heater core is heated by cooling water heated by the heater.

Description

Technical Field

[0001] This disclosure relates to a vehicle air conditioning unit that heats a heat transfer medium used in the vehicle's air conditioning system. Background Technology

[0002] Japanese Patent Application Publication No. 2014-129054 discloses an air conditioning system for a hybrid electric vehicle. This system heats the heater core by guiding a heat transfer medium heated by waste heat from the engine or by a heater to the heater core. Warm air is obtained by passing air through the heated heater core. Specifically, the system has a first flow path for heating the heat transfer medium using waste heat from the engine in HEV driving mode (driving mode powered by both the engine and electric motor) or engine-only driving mode (driving mode powered only by the engine). The system also has a second flow path for heating the heat transfer medium using a heater in EV driving mode (driving mode powered only by the electric motor). Furthermore, the system includes a three-way valve for switching between the first and second flow paths. By switching the flow paths using the three-way valve, the system heats the heat transfer medium using a heater in EV driving mode. Furthermore, the vehicle's air conditioning system uses a three-way valve to switch the flow path, and in HEV driving mode or engine-only driving mode, it uses the engine's waste heat to heat the heat transfer medium. Summary of the Invention

[0003] In the vehicle air conditioning system described in Japanese Patent Application Publication No. 2014-129054, a portion of the second flow path used in EV driving mode is shared with the first flow path used in HEV driving mode or engine-only driving mode. Furthermore, in HEV driving mode or engine-only driving mode, the heat transfer medium also circulates in this portion. On the other hand, there is a flow path in the second flow path that is closed by a three-way valve in HEV driving mode or engine-only driving mode, preventing the heat transfer medium from circulating. Furthermore, in HEV driving mode or engine-only driving mode, the temperature of the heat transfer medium retained in this flow path sometimes decreases due to the influence of cold outside air. If the driving mode is switched from HEV driving mode or engine-only driving mode to EV driving mode, the heat transfer medium, whose temperature has decreased after being retained in this flow path, flows into the heater core. Furthermore, the temperature of the heater core may decrease.

[0004] The purpose of this disclosure is to suppress the temperature drop of the heat transfer medium circulating in the second flow path in a vehicle air conditioning device that heats a heat transfer medium circulating in a first flow path and a second flow path, when the flow path for heating the heat transfer medium is switched from the first flow path to the second flow path. The vehicle air conditioning device includes: a first flow path in which the heat transfer medium is heated by a first heat source, and a second flow path in which the heat transfer medium is heated by a second heat source.

[0005] One aspect of this disclosure is a vehicle air conditioning unit that heats a heat transfer medium.

[0006] Vehicle air conditioning units that heat the heat transfer medium have the following features:

[0007] The heat transfer medium used in the vehicle's air conditioning circulates in this first flow path;

[0008] The second flow path is partially shared with the first flow path, and the heat transfer medium circulates in the second flow path;

[0009] A three-way valve is used to switch the first flow path and the second flow path; and

[0010] A control device controls the opening and closing of the three-way valve.

[0011] In the first flow path, the heat transfer medium is heated by heat from a first heat source.

[0012] In the second flow path, the heat transfer medium is heated by heat from a second heat source.

[0013] The second flow path includes a third flow path, which is closed by the three-way valve and the heat transfer medium does not circulate in the third flow path when the first flow path is used as a flow path for heating the heat transfer medium.

[0014] When the flow path for heating the heat transfer medium is switched from the first flow path to the second flow path, the control device controls the opening and closing of the three-way valve in such a way that the heat transfer medium in the first flow path and the heat transfer medium in the third flow path are mixed before the switch.

[0015] According to the above structure, when the flow path for heating the heat transfer medium is switched from the first flow path to the second flow path, before this switch, when the first flow path is used as the flow path for heating the heat transfer medium, the cooling water retained in the third flow path mixes with the cooling water in the first flow path. By temporarily mixing the cooling water retained in the third flow path with the cooling water heated by the first heat source, even if the temperature of the cooling water retained in the third flow path drops due to outside air, the temperature drop of the cooling water circulating in the second flow path can be suppressed.

[0016] It is possible that, when the temperature change of the heat transfer medium after mixing in the first flow path and the third flow path is less than a threshold, the control device controls the opening and closing of the three-way valve by switching the flow path used to heat the heat transfer medium to the second flow path.

[0017] If the temperature difference between the heat transfer medium in the first flow path and the heat transfer medium in the third flow path is less than a threshold after they are mixed, the control device controls the opening and closing of the three-way valve by switching the flow path used to heat the heat transfer medium to the second flow path.

[0018] It is possible that the first heat source is an internal combustion engine and the second heat source is a heater.

[0019] According to this disclosure, in a vehicle air conditioning unit that heats a heat transfer medium circulating in a first flow path and a second flow path, when the flow path for heating the heat transfer medium is switched from the first flow path to the second flow path, it is possible to suppress a temperature drop of the heat transfer medium circulating in the second flow path. The vehicle air conditioning unit includes: a first flow path in which the heat transfer medium is heated by a first heat source, and a second flow path in which the heat transfer medium is heated by a second heat source. Attached Figure Description

[0020] The features, advantages, and technical and industrial significance of exemplary embodiments of the present invention will be described below with reference to the accompanying drawings, in which the same reference numerals denote the same elements, wherein:

[0021] Figure 1 This is a block diagram showing the structure of a vehicle air conditioning unit;

[0022] Figure 2 This is a flowchart illustrating the operation of a vehicle's air conditioning unit;

[0023] Figure 3 This is a block diagram showing flow path A in HEV driving mode or engine-only driving mode;

[0024] Figure 4 This is a block diagram showing the flow path C when the three-way valve is fully open;

[0025] Figure 5 This is a block diagram showing the flow path B in EV driving mode;

[0026] Figure 6 It is a coordinate graph showing the time-varying opening of the three-way valve. Detailed Implementation

[0027] Reference Figure 1 To illustrate the implementation method, we will describe the vehicle air conditioning unit 10. Figure 1 This is a block diagram illustrating the structure of a vehicle air conditioning unit 10 according to an embodiment.

[0028] The vehicle air conditioning unit 10 is installed in a hybrid electric vehicle. The vehicle air conditioning unit 10 is a device that realizes the heating system in the air conditioning unit (A / C) of the hybrid electric vehicle.

[0029] The hybrid electric vehicle includes an engine 12, exemplified by an internal combustion engine, and an electric motor (not shown). The hybrid electric vehicle operates in any of the following driving modes: EV driving mode, HEV driving mode, and engine-only driving mode. EV driving mode is the mode in which the vehicle operates solely using the electric motor as a power source. In EV driving mode, the electric motor uses electricity supplied from the battery to generate driving force. HEV driving mode is the mode in which the vehicle operates using both the engine 12 and the electric motor as power sources. Engine-only driving mode is the mode in which the vehicle operates solely using the engine as a power source. An air conditioning unit 10 can also be installed in a plug-in hybrid electric vehicle.

[0030] The vehicle air conditioning unit 10 heats the heater core 16 by guiding the heat transfer medium, either waste heat from the engine 12 or heat from the heater 14, to the heater core 16. Warm air is then obtained by passing air from the blower 18 through the heated heater core 16. This realizes a heating system in the air conditioning unit (A / C) of a hybrid electric vehicle. The heater 14 is, for example, an electric heater that heats cooling water.

[0031] The vehicle air conditioning unit 10 includes piping 20 to 30, a three-way valve 32, and an electric pump 34. The engine 12, heater 14, heater core 16, three-way valve 32, and electric pump 34 are connected by piping 20 to 30. Additionally, cooling water for cooling the engine 12 circulates through piping 20 to 30. Cooling water is an example of a heat transfer medium. A water pump is provided in the engine 12 to circulate the cooling water within the engine 12.

[0032] Engine 12 and three-way valve 32 are connected by piping 20. Three-way valve 32 and heater 14 are connected by piping 22. An electric pump 34 is installed between three-way valve 32 and heater 14 to circulate cooling water within piping 20 to 30. It should be noted that this arrangement is only one example. Heater 14 and heater core 16 are connected by piping 24. Heater core 16 and three-way valve 32 are connected by piping 26 and piping 28. Specifically, one end of piping 26 is connected to heater core 16. The other end of piping 26 is connected to one end of piping 28 at connection point 36. The other end of piping 28 is connected to three-way valve 32. Heater core 16 and engine 12 are connected by piping 26 and piping 30. Specifically, the other end of piping 26 is connected to one end of piping 30 at connection point 36. The other end of piping 30 is connected to engine 12.

[0033] The three-way valve 32 is an electrically operated three-way valve. It switches the flow path of the cooling water circulation. The three-way valve 32 has three states: a first state, a second state, and a third state. The three-way valve 32 switches the flow path by changing its state.

[0034] The first state is one in which cooling water can circulate from pipe 20 to pipe 22. The second state is one in which cooling water cannot circulate from pipe 28 to pipe 22. When the three-way valve 32 is in the first state, flow path A is formed by pipes 20, 22, 24, 26, and 30. Flow path A is equivalent to an example of the first flow path.

[0035] The second state allows cooling water to circulate from pipe 28 to pipe 22. The second state also prevents cooling water from circulating from pipe 20 to pipe 22. When the three-way valve 32 is in the second state, flow path B is formed by pipes 22, 24, 26, and 28. Flow path A and flow path B share a common flow path formed by pipes 22, 24, and 26. Thus, flow path A and flow path B are partially shared flow paths. Flow path B is equivalent to an example of the second flow path.

[0036] The third state is one in which cooling water can circulate from pipe 20 to pipe 22 and from pipe 28 to pipe 22. The third state is when all valves constituting the three-way valve 32 are open. When the three-way valve 32 is in the third state, a flow path is formed by all pipes 20 to 30 (the flow path formed by flow paths A and B). Hereinafter, the flow path formed by all pipes 20 to 30 is referred to as "flow path C".

[0037] In flow path B, the cooling water does not pass through engine 12. Therefore, compared to flow path A, the length of the path through which the cooling water circulates is shorter. Consequently, in flow path B, the cooling water can circulate more efficiently than in flow path A. Therefore, the heating efficiency of the cooling water is high.

[0038] Additionally, the vehicle air conditioning unit 10 includes a control device 38. The control device 38 controls the switching of the flow path by controlling the state of the three-way valve 32.

[0039] The functions of the control device 38 are implemented, as an example, through the coordinated operation of hardware and software. For instance, a processor such as a central processing unit (CPU) reads and executes a program stored in the memory of the control device 38 to achieve its functions. The program is stored in the memory via a recording medium such as a CD or DVD, or via a communication path such as a network. The functions of each part of the control device 38 can also be implemented using application-specific integrated circuits (ASICs), field-programmable gate arrays (FPGAs), or other programmable logic devices. Alternatively, the functions of each part of the control device 38 can also be implemented using hardware such as electronic circuits.

[0040] Additionally, the vehicle air conditioning unit 10 includes temperature sensors 40, 42, and 44. Temperature sensor 40 is located near the coolant outlet of the engine 12. Temperature sensor 40 measures the temperature of the coolant flowing from the engine 12 and outputs its measured value to the control device 38. Temperature sensor 42 is located near the coolant inlet of the heater core 16. Temperature sensor 42 measures the temperature of the coolant flowing into the heater core 16 and outputs its measured value to the control device 38. Temperature sensor 44 is located near the coolant outlet of the heater core 16. Temperature sensor 44 measures the temperature of the coolant flowing from the heater core 16 and outputs its measured value to the control device 38. This example of temperature sensor placement is just one example. Temperature sensors located near the coolant inlet of the engine 12, etc., can also be used.

[0041] When the hybrid electric vehicle is in HEV driving mode or engine-only driving mode, the control device 38 switches the state of the three-way valve 32 to the first state. This forms flow path A. Furthermore, the cooling water flowing into the heater core 16 is heated by the waste heat from the engine 12. Additionally, the cooling water flowing into the heater core 16 is also heated by the heater 14.

[0042] When the hybrid electric vehicle is in EV mode, the control unit 38 switches the state of the three-way valve 32 to the second state. This forms flow path B. Furthermore, the cooling water flowing into the heater core 16 is not heated by the engine 12. The cooling water flowing into the heater core 16 is heated by the heater 14.

[0043] The following is for reference Figures 2 to 5 To explain the operation of the vehicle air conditioning unit 10. Figure 2 This is a flowchart illustrating the operation of the vehicle air conditioning unit 10. Figures 3 to 5 This is a block diagram showing the structure of a vehicle air conditioning unit 10.

[0044] Here, as an example, it is assumed that the driving mode of the hybrid electric vehicle is either HEV driving mode or engine-only driving mode. In this case, the control device 38 forms flow path A (S01) by switching the state of the three-way valve 32 to the first state.

[0045] exist Figure 3 Flow path A is shown. Pipes 20, 22, 24, 26, and 30, which circulate cooling water in piping 20 to 30, are represented by solid lines. Pipe 28, which does not circulate cooling water in piping 20 to 30, is represented by dashed lines.

[0046] In the first state, coolant does not flow from pipe 28 to pipe 22. Therefore, coolant does not circulate in pipe 28. Coolant remains in pipe 28. That is, pipe 28 is closed by the three-way valve 32 and coolant does not circulate. Pipe 28 is an example of a pipe forming a third flow path. The coolant remaining in pipe 28 is not heated by the waste heat of engine 12 or heater 14. Therefore, the temperature of the coolant remaining in pipe 28 becomes lower than the temperature of the coolant circulating in flow path A due to the influence of the low-temperature outside air.

[0047] If the control device 38 receives a flow path switching instruction (S02: Yes), it fully opens the three-way valve 32 (S03). That is, the control device 38 forms flow path C by switching the state of the three-way valve 32 to the third state. When the driving mode of the hybrid electric vehicle is switched from HEV driving mode or engine-only driving mode to EV driving mode, a flow path switching instruction is output to the control device 38. The control device 38 switches the state of the three-way valve 32 to the third state according to this switching instruction.

[0048] exist Figure 4 Flow path C is shown. Pipes 20 to 30 are all represented by solid lines. Cooling water circulates in pipes 20 to 30. Cooling water retained in pipe 28 flows into pipe 22. Furthermore, the cooling water retained in pipe 28 mixes with the cooling water circulating in flow path A.

[0049] If the control device 38 does not receive a flow path switching instruction (S02: No), it will not switch the state of the three-way valve 32. Furthermore, the control device 38 will maintain the state of the three-way valve 32 in the first state.

[0050] The control device 38 determines whether the temperature fluctuation of the cooling water near the outlet of the heater core 16 is less than a temperature fluctuation threshold (S04) based on the temperature measured by the temperature sensor 44. The temperature fluctuation threshold is a preset value. For example, the control device 38 determines whether the temperature fluctuation per unit time (e.g., per second) is less than the temperature fluctuation threshold (e.g., X °C / second).

[0051] If the temperature fluctuation of the cooling water near the outlet of heater core 16 is less than the temperature fluctuation threshold (S04: No), the control device 38 switches the flow path to flow path B by switching the state of the three-way valve 32 to the second state (S05). If the temperature fluctuation of the cooling water is not less than the temperature fluctuation threshold (S04: No), the control device 38 does not switch the state of the three-way valve 32. Furthermore, the control device 38 maintains the state of the three-way valve 32 in the third state. It should be noted that the control device 38 may also switch the state of the three-way valve 32 to the second state if the temperature fluctuation measured by the temperature sensor 42 is less than the temperature fluctuation threshold, or if the average temperature fluctuation of the temperature measured by the temperature sensor 42 and the temperature measured by the temperature sensor 44 is less than the temperature fluctuation threshold.

[0052] exist Figure 5 Flow path B is shown. Pipes 22, 24, 26, and 28, which circulate cooling water in piping 20 to 30, are represented by solid lines. Pipes 20 and 30, which do not circulate cooling water, are represented by dashed lines.

[0053] As described above, when the driving mode is switched from HEV driving mode or engine-only driving mode to EV driving mode, the coolant circulation path is not directly switched from path A to path B. Instead, the coolant circulation path is temporarily switched to path C. Afterward, the coolant circulation path is switched back to path B. Therefore, compared to the case where the flow path is directly switched from path A to path B, the temperature drop of the coolant flowing into the heater core 16 can be suppressed. This point will be explained below.

[0054] If the flow path is switched directly from flow path A to flow path B, the cooling water retained in pipe 28 mixes with the heated cooling water in pipes 22, 24, and 26. While the cooling water retained in pipe 28 is being cooled by the low-temperature outside air, this mixing causes the temperature of the cooling water circulating in flow path B to decrease.

[0055] On the other hand, if the flow path is not directly switched from flow path A to flow path B and is switched to flow path C, the cooling water retained in pipe 28 mixes with the cooling water heated in flow path A (cooling water in pipes 20, 22, 24, 26, and 30). As a result, the temperature of the cooling water circulating in flow path C decreases. Even in this case, since the cooling water retained in pipe 28 mixes with the cooling water in flow path A, which has a larger capacity than flow path B, the temperature drop of the mixed cooling water is less than when it mixes with the cooling water in the smaller capacity of flow path B. In other words, when the flow path is switched from flow path A to flow path C, the temperature drop of the mixed cooling water is less than when the flow path is directly switched from flow path A to flow path B. Therefore, by switching the flow path to flow path C, the temperature drop of the mixed cooling water is suppressed. Furthermore, the temperature drop of the heater core 16 can be suppressed.

[0056] The hypothesis is that if the temperature fluctuation of the cooling water near the outlet of heater core 16 is less than the temperature fluctuation threshold, then even if the flow path is switched from flow path C to flow path B, the possibility of a sharp drop in the temperature of the cooling water circulating in flow path B is low. Therefore, the flow path is switched from flow path C to flow path B.

[0057] Furthermore, the speed (e.g., flow rate) of the blower 18 is sometimes controlled based on the temperature of the cooling water. For example, sometimes the flow rate of the blower 18 increases as the temperature of the cooling water increases. In such control, if the temperature of the cooling water drops sharply, the flow rate of the blower 18 will drop sharply. According to the embodiment, the drop in temperature of the cooling water flowing into the heater core 16 can be suppressed, and therefore the drop in the flow rate of the blower 18 can be suppressed.

[0058] As another example of the processing in step S04, the control device 38 may switch the flow path to flow path B if a predetermined time has elapsed since the point at which the three-way valve 32 became fully open. This time is calculated based on the capacity of piping 20 to 30 and the cooling water. This time is estimated to be the time during which the temperature variation of the cooling water near the outlet of the heater core 16 is less than a temperature variation threshold.

[0059] As another example, when the blower 18's speed setting (e.g., flow rate) is controlled based on the cooling water temperature, the control device 38 can switch the flow path to flow path B if the flow rate variation of the blower 18 per unit time is less than a predetermined speed setting variation threshold (e.g., Y% / second). The speed setting variation threshold is presumed to be a value where the temperature variation of the cooling water near the outlet of the heater core 16 is less than a temperature variation threshold.

[0060] As another example, if the difference between the temperature measured by temperature sensor 40 (that is, the temperature of the coolant flowing from engine 12) and the temperature measured by temperature sensor 44 (that is, the temperature of the coolant flowing from heater core 16) is less than a predetermined temperature difference threshold, the control device 38 switches the flow path to flow path B. If the temperature difference is less than the temperature difference threshold, it is assumed that the temperature of the coolant in pipes 20 to 30 is uniform or close to it, therefore the control device 38 switches the flow path to flow path B. It should be noted that the temperature difference can also be calculated using the temperature measured by temperature sensor 42 instead of the temperature measured by temperature sensor 44.

[0061] Additionally, the control device 38 can gradually increase the opening degree of the three-way valve 32. Figure 6 This example is shown in the image. Figure 6 The horizontal axis in the graph represents time. Figure 6 The vertical axis in the figure represents the opening degree of the three-way valve 32.

[0062] Time T1 is the timing when control device 38 receives the flow path switching instruction. At this time, the opening degree D1 is the opening degree forming flow path A. Control device 38 gradually increases the opening degree from time T1 to time T2. The opening degree D2 is fully open. Opening degree D2 is the opening degree forming flow path C. By gradually increasing the opening degree, the cooling water retained in piping 28 gradually mixes with the cooling water in flow path A. Therefore, the temperature change of the cooling water in flow path C is slowed down. Figure 6 In the example shown, the opening is changed linearly. However, the opening can also be changed incrementally.

[0063] In the above embodiment, engine 12 is used as the first heat source, and heater 14 is used as the second heat source. However, the type and combination of heat sources are not limited to this. For example, a fuel cell can also be used as the first heat source. Alternatively, a heat pump can be used as the second heat source. For example, a vehicle air conditioning unit 10 can be installed in a fuel cell electric vehicle that uses a fuel cell as the first heat source instead of engine 12. In this case, if flow path A is formed, the cooling water is heated by heat from the fuel cell.

Claims

1. A vehicle air conditioning unit that heats a heat transfer medium, comprising: The heat transfer medium used in the vehicle's air conditioning system circulates in the first flow path. The second flow path is partially shared with the first flow path, and the heat transfer medium circulates in the second flow path; A three-way valve is used to switch between the first flow path and the second flow path. and The control device controls the opening and closing of the three-way valve. in: In the first flow path, the heat transfer medium is heated by heat from the first heat source; In the second flow path, the heat transfer medium is heated by heat from a second heat source; The second flow path includes a third flow path, which, when the first flow path is used as a flow path for heating the heat transfer medium, is closed by the three-way valve and the heat transfer medium does not circulate in the third flow path; and When the flow path for heating the heat transfer medium is switched from the first flow path to the second flow path, the control device controls the opening and closing of the three-way valve in such a way that the heat transfer medium in the first flow path and the heat transfer medium in the third flow path are mixed before the switch.

2. The vehicle air conditioning unit according to claim 1, wherein: When the temperature change of the heat transfer medium after mixing in the first flow path and the third flow path is less than a threshold, the control device controls the opening and closing of the three-way valve by switching the flow path used to heat the heat transfer medium to the second flow path.

3. The vehicle air conditioning unit according to claim 1, wherein: When the temperature difference between the heat transfer medium in the first flow path and the heat transfer medium in the third flow path is less than a threshold after they are mixed, the control device controls the opening and closing of the three-way valve by switching the flow path used to heat the heat transfer medium to the second flow path.

4. The vehicle air conditioning unit according to any one of claims 1 to 3, wherein: The first heat source is an internal combustion engine, and The second heat source is a heater.

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