Vehicle air conditioning system

Abstract

The present invention provides a vehicle air conditioning system that can stably obtain air conditioning performance in the vehicle cabin even when the FC water circuit and the heating water circuit are switched between a standalone circuit state and a linked circuit state. [Solution] When the flow path switching valve 22 switches the communication state between the second circulation flow path 20, which is equipped with a heater core 21 and a water heater 24, and the first circulation flow path 10, which is equipped with a radiator 12, the control constant map for controlling the heating of the water heater 24 is changed from a first control constant map with small control constants to a second control constant map with large control constants. This makes it possible to change the amount of heating of the water heater 24 in response to rapid fluctuations in the inlet water temperature of the water heater 24, and to stably maintain the temperature of the cooling water introduced into the heater core 21, thereby maintaining high air conditioning performance in the vehicle cabin.

Description

Technical Field

[0006] , , ,

[0001] The present invention relates to a vehicle air conditioner.

Background Art

[0002] Conventionally, in a fuel cell vehicle (FCEV: Fuel Cell Electric Vehicle) that runs using the electric power generated by a fuel cell stack, there is an air conditioner configured to be able to utilize the waste heat of the fuel cell stack for heating the interior of the vehicle.

[0003] Specifically, in this type of air conditioner, by supplying the cooling water heated by the waste heat of the fuel cell stack to a heater core (a heater core for heating the air for air conditioning), the heating effect in the vehicle interior is improved. Also, when the temperature of the cooling water supplied to the heater core is lower than the target water temperature at the inlet of the heater core, it is common to heat the cooling water using a water heater (electric heater) or the like.

[0004] As a configuration of a general cooling water circulation circuit in this type of air conditioner, as disclosed in Patent Document 1, the FC water circuit and the heating water circuit are connected via a flow path switching valve such as a three-way valve. That is, it is possible to switch between a state where the FC water circuit and the heating water circuit are communicated by the flow path switching valve (a state where the cooling water heated by the waste heat of the fuel cell stack is supplied to the heater core; hereinafter, referred to as the circuit cooperation state) and a state where the flow path switching valve is separated from the FC water circuit (hereinafter, referred to as the circuit independent state).

Prior Art Documents

Patent Documents

[0005] <00,00023>

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0006] Incidentally, when the flow path of the cooling water is switched between the independent circuit state and the linked circuit state by the flow path switching valve, the inlet water temperature of the water heater may fluctuate rapidly. If such a rapid fluctuation in the inlet water temperature occurs, the control of the water heater may lag behind in responding to the fluctuation (for example, even though the inlet water temperature of the water heater has dropped rapidly, the amount of heating by the water heater may be insufficient, resulting in a low temperature of the cooling water flowing into the heater core), which may temporarily lead to a situation where the air conditioning performance inside the vehicle cabin is not sufficient.

[0007] The present invention has been made in view of the above, and its objective is to provide a vehicle air conditioning system that can stably obtain air conditioning performance in the vehicle cabin even when the flow path of the cooling water is switched between a circuit-only state and a circuit-connected state. [Means for solving the problem]

[0008] The present invention provides a solution for achieving the above objectives, based on a vehicle air conditioning system comprising: a first circulation passage equipped with a radiator through which coolant circulates and which dissipates heat from the coolant; a second circulation passage equipped with a heater core that heats the air supplied to the vehicle interior by heat exchange with the coolant, and a heater that heats the coolant introduced into the heater core by control according to a control constant map; and a flow path switching valve capable of switching the communication state between the first circulation passage and the second circulation passage. Furthermore, this vehicle air conditioning system is characterized by comprising a control constant map changing unit that changes the control constant map that controls the heater, provided that the communication state between the first circulation passage and the second circulation passage has been switched by the flow path switching valve.

[0009] When the communication state between the first and second circulation channels is switched, the heater inlet water temperature (the temperature of the coolant flowing into the heater) may fluctuate rapidly. In this case, the heater can be controlled to respond to this rapid fluctuation in inlet water temperature by changing the control constant map that controls the heater. For example, if the heater inlet water temperature drops rapidly, the control constant map can be changed to one that provides control constants that rapidly increase the amount of heating the heater, thereby stably maintaining the temperature of the coolant introduced into the heater core. This allows for maintaining high air conditioning performance in the vehicle cabin. [Effects of the Invention]

[0010] In this invention, the control constant map for controlling the heater is changed based on the condition that the communication state between the first circulation path equipped with a radiator and the second circulation path equipped with a heater core and heater is switched by a flow path switching valve. This makes it possible to control the heater in response to rapid fluctuations in the heater inlet water temperature, maintain a stable temperature of the coolant introduced into the heater core, and maintain high air conditioning performance in the vehicle cabin. [Brief explanation of the drawing]

[0011] [Figure 1] This diagram schematically shows the cooling water circulation circuit of the air conditioning system and fuel cell stack cooling system according to the embodiment, where Figure 1(a) shows the circuit in a standalone state and Figure 1(b) shows the circuit in a linked state. [Figure 2] This block diagram shows the schematic configuration of the control system for the cooling water circulation circuit. [Figure 3] This is a flowchart illustrating the procedure for switching control constant maps. [Modes for carrying out the invention]

[0012] Hereinafter, embodiments of the present invention will be described based on the drawings.

[0013] - Configuration of the cooling water circulation circuit - Figure 1 is a schematic diagram showing the cooling water circulation circuit 1 of the air conditioning system and fuel cell stack cooling system according to this embodiment, where Figure 1(a) shows the circuit in a standalone state (described later) and Figure 1(b) shows the circuit in a linked state (described later). Figure 2 is a block diagram showing the schematic configuration of the control system of the cooling water circulation circuit 1.

[0014] The cooling water circulation circuit 1 is installed in a fuel cell vehicle (not shown) and, as shown in Figure 1, has a configuration comprising a first circulation channel (also called the FC water circuit) 10 and a second circulation channel (also called the heating water circuit) 20.

[0015] The first circulation channel 10 is configured such that the fuel cell stack 11, radiator 12, water pump 13, rotary valve 14, and intercooler 15 are connected by cooling water pipes 16 to 19 to enable the circulation of cooling water. The fuel cell stack 11 and the radiator 12 are connected by the first pipe 16 and the second pipe 17. The water pump 13 is installed in the first pipe 16 and circulates the cooling water in the first circulation channel 10. The rotary valve 14 is installed in the second pipe 17 and is connected to a bypass pipe 18 that bypasses the radiator 12. The intercooler 15 is installed in the third pipe 19 that connects the first pipe 16 and the second pipe 17. In addition, a first water temperature sensor 10a is installed on the inlet side of the fuel cell stack 11 (downstream end of the first pipe 16) to detect the inlet water temperature of the fuel cell stack 11. A second water temperature sensor 10b for detecting the outlet water temperature of the fuel cell stack 11 is installed at the outlet side of the fuel cell stack 11 (the upstream end of the second pipe 17).

[0016] The configuration and function of the fuel cell stack 11, radiator 12, water pump 13, and intercooler 15 are well known, so their description is omitted here.

[0017] The rotary valve 14 is a solenoid valve that can switch between the cooling water circulating in the first circulation passage 10 passing through the radiator 12 and bypassing the radiator 12. The rotary valve 14 is controlled by the ECU 100 to open and close when the inlet water temperature of the fuel cell stack 11 detected by the first water temperature sensor 10a exceeds the target inlet water temperature required to cool the fuel cell stack 11, so that the cooling water flows through the radiator 12. On the other hand, when the inlet water temperature of the fuel cell stack 11 detected by the first water temperature sensor 10a is below the target inlet water temperature, the rotary valve 14 is controlled by the ECU 100 so that the cooling water flows through the intercooler 15 and the fuel cell stack 11 respectively without passing through the radiator 12.

[0018] The second circulation channel 20 is configured such that a heater core 21, which heats the conditioned air through heat exchange between the conditioned air and the cooling water, a flow path switching valve 22, a water pump 23, and a water heater (heater in this invention) 24, which heats the cooling water supplied to the heater core 21, are connected by cooling water pipes 25 to 27 to enable the circulation of the cooling water. The heater core 21 and the flow path switching valve 22 are connected by a fourth pipe 25. The heater core 21 and the water heater 24 are connected by a fifth pipe 26. The flow path switching valve 22 and the water heater 24 are connected by a sixth pipe 27. The water pump 23 is installed in the sixth pipe 27 and circulates the cooling water in the second circulation channel 20. A third water temperature sensor 20a is installed on the inlet side of the heater core 21 (downstream end of the fifth pipe 26) to detect the inlet water temperature of the heater core 21. A fourth water temperature sensor 20b is installed at the outlet side of the heater core 21 (the upstream end of the fourth pipe 25) to detect the outlet water temperature of the heater core 21.

[0019] The configuration and function of the heater core 21, water pump 23, and water heating heater 24 are well known, so their description is omitted here.

[0020] Between the flow path switching valve 22 and the second pipe 17, they are connected by an introduction pipe 31 and a discharge pipe 32. The introduction pipe 31 is a pipe that introduces a part of the cooling water flowing through the second pipe 17 into the second circulation flow path 20 via the flow path switching valve 22. The discharge pipe 32 is a pipe that discharges a part of the cooling water flowing through the second circulation flow path 20 into the first circulation flow path 10 via the flow path switching valve 22. The flow path switching valve 22 switches the connection state between the first circulation flow path 10 and the second circulation flow path 20, thereby bringing the first circulation flow path 10 and the second circulation flow path 20 into a communicating state (a state where the cooling water heated by the waste heat of the fuel cell stack 11 is supplied to the heater core 21) (see Fig. 1(b)), and a circuit single state (see Fig. 1(a)) where the second circulation flow path 20 is separated from the first circulation flow path 10 and the cooling water is circulated in each of the circulation flow paths 10 and 20.

[0021] In the above-mentioned circuit cooperation state, as shown in Fig. 1(b), the flow path switching valve 22 communicates the introduction pipe 31 with the sixth pipe 27 and also communicates the discharge pipe 32 with the fourth pipe 25. As a result, the cooling water introduced from the first circulation flow path 10 into the second circulation flow path 20 flows through the water pump 23, the water heating heater 24, and the heater core 21 in sequence and then returns to the first circulation flow path 10.

[0022] Specifically, when there is no or low heating requirement in the vehicle interior, the flow path switching valve 22 is switched by the ECU 100 to separate the second circulation flow path 20 from the first circulation flow path 10. On the other hand, when the heating requirement in the vehicle interior is high, the flow path switching valve 22 is switched by the ECU 100 to communicate the first circulation flow path 10 and the second circulation flow path 20.

[0023] When the waste heat from the fuel cell stack 11 is used for heating, the water heater 24 is controlled by the ECU 100 to heat the cooling water discharged from the outlet of the fuel cell stack 11 and flowing into the second circulation channel 20, raising the temperature of the cooling water to a level (the target water temperature at the inlet of the heater core 21) that can be used as a heat source for heating the vehicle interior, if the outlet water temperature of the fuel cell stack 11 detected by the second water temperature sensor 10b is lower than the target water temperature at the inlet of the heater core 21. The cooling water heated by the water heater 24 flows through the heater core 21, and the heater core 21 heats the air supplied to the vehicle interior. The water heater 24 may also be controlled according to the inlet water temperature of the heater core 21 detected by the third water temperature sensor 20a.

[0024] As described above, the water temperature information detected by each water temperature sensor 10a, 10b, 20a, and 20b is input to the ECU 100 as a water temperature signal. The ECU 100 also controls the switching of each water pump 13, 23, rotary valve 14, and flow path switching valve 22, and controls the output of the water heating heater 24.

[0025] As described above, the ECU 100 controls the switching of the flow path switching valve 22 and the rotary valve 14, as well as the output of the water heater 24, based on the water temperature detected by each water temperature sensor 10a, 10b, 20a, and 20b, and the target water temperature at the inlet of the fuel cell stack 11 and the heater core 21. This control of the output of the water heater 24 is performed according to control constants set by a control constant map pre-stored in the ECU 100. The control of the water heater 24 by this control constant map will be described later.

[0026] In conventional technology, the flow path of the cooling water was switched between the independent circuit state and the linked circuit state by a flow path switching valve. If the water temperature at the inlet of the water heater fluctuated rapidly, there was a delay in the control of the water heater in response to this fluctuation, potentially leading to a situation where the air conditioning performance inside the vehicle cabin was temporarily insufficient.

[0027] In view of this point, this embodiment modifies the control constant map for heating the water heater 24 when the flow path of the cooling water is switched between the circuit-only state and the circuit-linked state by the flow path switching valve 22. The configuration of the ECU 100 for realizing this operation will be described below.

[0028] As shown in Figure 2, the ECU 100 includes a memory unit 110, a switching control unit 120, and a control constant map changing unit 130 as functional units realized by a control program.

[0029] The memory unit 110 stores multiple control constant maps used to control the heating amount of the water heater 24. For example, it stores a first control constant map that is used when a predetermined time has elapsed since the vehicle's start switch was turned ON or when the cooling water flow path was switched between a single circuit state and a linked circuit state, and a second control constant map that is used when the cooling water flow path was switched between a single circuit state and a linked circuit state. The first control constant map is selected when the heating amount of the water heater 24 is controlled by relatively small control constants (PID control). On the other hand, the second control constant map is selected when the heating amount of the water heater 24 is controlled by relatively large control constants.

[0030] The switching control unit 120 determines whether it is necessary to switch the cooling water flow path between a standalone circuit state and a linked circuit state, and if it determines that a switch is necessary, it transmits a switching command signal to the flow path switching valve 22. For example, in a situation where the circuit is in a standalone state, if a heating request is made in the vehicle cabin, and the outlet water temperature of the fuel cell stack 11 detected by the second water temperature sensor 10b is above a predetermined temperature, a switching command signal to the linked circuit state is transmitted to the flow path switching valve 22 in order to utilize the waste heat from the fuel cell stack 11 for heating. This switching command signal is also output to the control constant map change unit 130.

[0031] The control constant map modification unit 130 changes the control constant map used to control the heating amount of the water heater 24, provided that it has received the switching command signal. Specifically, it reads the second control constant map from the storage unit 110 and changes the control constant map used to control the heating amount of the water heater 24 from the first control constant map to the second control constant map. In other words, provided that the cooling water flow path is switched between a circuit-only state and a circuit-linked state, the control constant map used to control the heating amount of the water heater 24 is switched from the first control constant map, which has relatively small control constants, to the second control constant map, which has relatively large control constants. Furthermore, after switching to the second control constant map in this way, the control constant map used to control the heating amount of the water heater 24 is returned to the first control constant map after a predetermined time has elapsed.

[0032] -Control constant map switching process- Next, the control constant map switching process in the cooling water circulation circuit 1 configured as described above will be explained. Figure 3 is a flowchart showing the procedure for the control constant map switching process. This flowchart is executed repeatedly when the vehicle's start switch is ON.

[0033] First, with the vehicle's start switch turned ON and the first control constant map selected as the control constant map used to control the amount of heat generated by the water heater 24, step ST1 determines whether the cooling water flow path has been switched between the circuit-only state and the circuit-linked state. This determination is made by the switching control unit 120 as described above. If the cooling water flow path has not been switched and the determination in step ST1 is NO, the process returns to the previous state.

[0034] On the other hand, if the cooling water flow path is switched and a YES determination is made in step ST1, the process moves to step ST2, where the control constant map used to control the heating amount of the water heater 24 is switched from the first control constant map to the second control constant map. This operation is performed by the control constant map changing unit 130. As a result, the control of the heating amount of the water heater 24 is switched to one using relatively large control constants.

[0035] In step ST3, once the control constant map has been switched, the timer in the ECU 100 starts operating. This timer times out after a predetermined period of time has elapsed. This predetermined period can be set arbitrarily, but it is determined in advance through experimentation or simulation so that the period for controlling the amount of heating of the water heater 24 using the second control constant map is appropriate (for example, so that it is an appropriate period for obtaining stable air conditioning performance in the vehicle cabin).

[0036] Subsequently, the process moves to step ST4, where it is determined whether the timer has timed out or not. If the timer has not yet timed out and step ST4 determines NO, the current selection state of the control constant map is maintained.

[0037] If the timer expires and a YES result is obtained in step ST4, the process moves to step ST5, where the control constant map used to control the heating amount of the water heater 24 is switched (reverted) from the second control constant map to the first control constant map, and the process returns. This returns the control of the heating amount of the water heater 24 to a relatively small control constant. This process is repeated.

[0038] -Effects of the embodiment- As described above, in this embodiment, the control constant map for controlling the water heater 24 is changed on the condition that the communication state between the first circulation path 10 and the second circulation path 20 is switched by the flow path switching valve 22. This makes it possible to control the water heater 24 to respond to rapid fluctuations in the inlet water temperature of the water heater 24, suppress the delay in the control of the water heater 24 in responding to rapid fluctuations in the inlet water temperature, and maintain a stable temperature of the cooling water introduced into the heater core 21, thereby maintaining high air conditioning performance in the vehicle cabin. In addition, it is possible to reduce the power consumption of the water heater 24.

[0039] -Other Embodiments- Furthermore, the present invention is not limited to the embodiments described above, and all modifications and applications are possible within the scope of the claims and equivalents thereof.

[0040] In the present invention, the situation in which the cooling water flow path is switched between a single circuit state and a linked circuit state includes not only the case where it is switched from a single circuit state to a linked circuit state, but also the case where it is switched from a linked circuit state to a single circuit state. In other words, in either case, the control constant map used to control the amount of heat of the water heater 24 is switched from the first control constant map to the second control constant map for a predetermined time, thereby allowing an increase in the inlet water temperature of the water heater 24 to be expected. [Industrial applicability]

[0041] The present invention is applicable to the control of a water heating element in a cooling water circulation circuit in an air conditioning system for a fuel cell vehicle. [Explanation of symbols]

[0042] 10...First circulation channel 12...Radiator 20...Second circulation channel 21...Heater core 22...Flow path switching valve 24...Water heating heater (heater) 100...ECU 130...Control constant map modification section

Claims

[Claim 1] A first circulation channel is provided which coolant circulates and which also includes a radiator that dissipates heat from the coolant, A second circulation channel comprising a heater core that heats the air supplied to the passenger compartment by heat exchange with the cooling water, and a heater that heats the cooling water introduced into the heater core by control according to a control constant map, A vehicle air conditioning system comprising a flow path switching valve capable of switching the communication state between the first circulation flow path and the second circulation flow path, A vehicle air conditioning system characterized by comprising a control constant map changing unit that changes the control constant map for controlling the heater, provided that the communication state between the first circulation path and the second circulation path is switched by the flow path switching valve.

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