Air conditioning device for fuel cell vehicle

Abstract

The present invention provides an air conditioning device for a fuel cell vehicle, which utilizes a fuel cell stack to improve the efficiency of heating, thereby increasing the driving distance. The air conditioning device for a fuel cell vehicle comprises: a heater core (30) in which a heat medium from a fuel cell stack (10) circulates and performs heating by heat exchange with air; and a control unit (40) which calculates the driving resistance when driving on the road based on the road state and environmental state that affect the driving resistance generated when the vehicle is driving, and controls the heat exchange in the heater core (30) based on the calculated driving resistance. The control unit (40) limits the operation related to heating using the waste heat of the fuel cell stack 10 when the driving resistance is greater than a predetermined value.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims priority to Japanese Patent Application No. 2021-019989 filed on February 10, 2021, which is hereby incorporated by reference in its entirety, including specification, claims, drawings, and abstract. Technical Field

[0003] The present disclosure relates to an air conditioning device for a fuel cell vehicle that utilizes waste heat from a fuel cell stack for heating. Background Art

[0004] A fuel cell vehicle that runs on electricity generated by a fuel cell is known. In the fuel cell, heat is generated when it generates electricity, and it is proposed to use the waste heat generated in the fuel cell for heating. In particular, in the fuel cell, the amount of heat generated can be controlled by controlling the power generation efficiency, so that the amount of heat corresponding to the heating requirement can be output.

[0005] In JP2015-209030, cooling water is circulated to cool the fuel cell, but high-temperature cooling water discharged from the fuel cell is used for heating, and a plurality of cooling water circulation systems are prepared to optimize heating according to the temperature of the cooling water.

[0006] Here, in the past, the excess heat generated in the fuel cell (heating heat for heating) was determined based on the heating requirement without considering the driving state. However, the waste heat of the fuel cell varies depending on the driving state, so there are cases where the additional heat for heating is not required depending on the driving state. In particular, the energy efficiency of the heat generated for heating in the fuel cell is low, and the maximum driving distance of the vehicle is shortened due to the heat generation. Summary of the invention

[0007] One example of the present disclosure is an air-conditioning device for a fuel cell vehicle that utilizes waste heat from a fuel cell stack for heating. The air-conditioning device for the fuel cell vehicle includes: a heater core that circulates a heat medium from the fuel cell stack and performs heating by heat exchange with air; and a control unit that calculates a driving resistance when driving on a road based on road conditions and environmental conditions that affect driving resistance generated when the vehicle is driving, and controls heat exchange in the heater core based on the calculated driving resistance. The control unit limits operations related to heating using waste heat from the fuel cell stack when the calculated driving resistance is above a predetermined value.

[0008] The road condition may include a road gradient of the traveling road and a friction coefficient of a standard road surface of the road.

[0009] The above-mentioned environmental conditions may include the temperature and rainfall conditions during driving.

[0010] The control unit may limit the operation related to heating using waste heat of the fuel cell stack when a difference between a standard running resistance when the road state and the environmental state are in a standard state and the calculated running resistance is greater than a predetermined value.

[0011] In addition, the fuel cell vehicle may have a navigation device for providing route guidance on a set route, the control unit may calculate the driving resistance on the set route, and the control unit may limit operations related to heating using waste heat from the fuel cell stack based on the driving resistance on the set route.

[0012] Effects of the Invention

[0013] According to the present disclosure, heating by exhaust heat from the fuel cell stack is limited in consideration of the running resistance, thereby making it possible to improve the efficiency of the operation of the fuel cell stack and maintain a large maximum running distance. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 1 is a block diagram showing the overall configuration of an air conditioning system using the FC group 10 .

[0015] Figure 2 It is a diagram showing the state of the heating alone mode.

[0016] Figure 3 It is a diagram showing the state of the cooperation mode of heating.

[0017] Figure 4 1 is a flowchart showing the processing of the waste heat request to the FC stack 10 for heating.

[0018] Figure 5 This is a flowchart of processing when predicting running resistance.

[0019] Figure 6 1 is a diagram showing a restriction state regarding the waste heat requirement of the FC stack 10 . DETAILED DESCRIPTION

[0020] Hereinafter, embodiments of the present disclosure will be described based on the drawings. It should be noted that the present disclosure is not limited to the embodiments described here.

[0021] "System Structure"

[0022] Figure 1This is a block diagram showing the overall structure of an air conditioning system using a fuel cell stack (FC stack) 10. The FC stack 10 generates electricity by burning fuel gas such as hydrogen, and has a hydrogen circulation system, an air supply and exhaust system, and an output system for generated electricity. That is, in the fuel cell unit, the energy obtained by burning hydrogen is output as electrical energy.

[0023] Here, the operation of the FC group 10 is controlled by the circulation amount of hydrogen, the supply amount of air, the size of the output power, etc. Usually, it is operated under the optimal operating conditions, but the power generation efficiency can be controlled by changing the operating conditions, and the heat generation (waste heat) will increase by reducing the power generation efficiency. Therefore, the waste heat can be increased according to the heating demand, and the waste heat can be used for heating by heating the heat medium (usually water) using the waste heat.

[0024] The FC stack 10 generates heat due to power generation. Therefore, a heat medium circulation path is provided in the FC stack 10, and the heat medium circulates through the FC stack 10 to the radiator 12 to be cooled. Figure 1 In the embodiment, a pump 16 is provided on a pipe 14-1 connecting the radiator 12 and the FC stack 10. A rotary valve 18 is provided on a pipe 14-2 connecting the FC stack 10 and the radiator 12, and a branch pipe 14-3 from the pipe 14-1 is connected to the rotary valve 18.

[0025] Therefore, the pump 16 is driven to supply the heat medium from the radiator 12 to the FC stack 10 via the pipe 14-1, and the heat medium from the fuel cell stack is supplied to the radiator 12 via the pipe 14-2, whereby the heat medium circulates in the FC stack 10 and the radiator 12, and the heat absorbed in the FC stack 10 is dissipated at the radiator 12, thereby cooling the FC stack 10.

[0026] The pipe 14-2 is connected to a branch passage 20-1, to which a heater core 30 is connected via a three-way valve 22, a pump 24, and a heater 26. The heater core 30 is connected to the pipe 14-2 via the branch passage 20-2. The branch passage 20-2 is also connected to the three-way valve 22 via a branch passage 20-3.

[0027] Therefore, by connecting the branch path 20-1 to the pump 24 using the three-way valve 22, the heat medium from the FC stack 10 can be supplied to the heater 26 and the heater core 30 by the pump 24 and then returned to the pipeline 14-2. In addition, by selecting the branch path 20-3 using the three-way valve 22, the heat medium from the pump 24 can be circulated in the path of the heater 26, the heater core 30, and the three-way valve 22.

[0028] The rotary valve 18 can supply the heat medium from the pipe 14-2 and the branch pipe 14-3 to the radiator 12 at an arbitrary ratio. That is, the rotary valve 18 can control the ratio of the heat medium circulating in the radiator 12 and the heat medium circulating in the FC stack 10.

[0029] The control unit 40 controls various components, controls the three-way valve 22 to switch the circulation mode of the heat medium according to an input signal, changes the flow rates of the pumps 16 and 24 , and controls the heating amount of the heater 26 and the waste heat of the FC stack 10 .

[0030] In addition, a navigation device 42 is connected to the control unit 40. The navigation device 42 has map data, etc., and displays the current location on a map based on a signal from a current location detection unit such as a GPS device, and searches for a route to the destination when a destination is set and provides route guidance. It should be noted that the navigation device 42 has a communication function and can obtain map information and route information from a server on the cloud, etc.

[0031] "Loop Mode"

[0032] <Single Mode>

[0033] exist Figure 2 2 shows the state of the heating single mode. In the single mode, the three-way valve 22 is used to close the path from the pipe 14-2, so that the heat medium from the branch path 20-3 circulates to the heater 26 and the heater core 30. Therefore, the heat exchange of the heater core 30 can be controlled by the heat generated by the heater 26, and the heating can be controlled in a manner that is isolated from the heat generated by the FC stack 10.

[0034] <Collaboration Mode>

[0035] exist Figure 3 2 shows the state of the cooperation mode for heating. In the cooperation mode, the three-way valve 22 is used to close the path from the branch path 20-3, so that the heat medium from the pipeline 14-2 returns to the pipeline 14-2 after passing through the heater 26 and the heater core 30. Therefore, the heat exchange of the heater core 30 is controlled by both the heat generated by the FC group 10 and the heat generated by the heater 26.

[0036] <Intermediate Mode>

[0037] It should be noted that an intermediate mode may be provided in which both the independent circulation through the branch path 20 - 3 and the circulation of the heat medium from the pipeline 14 - 2 are used in combination.

[0038] "Heating control"

[0039] <Usually>

[0040] Normally, corresponding to the heating requirement in the vehicle interior, the operating conditions of the heater core 30 are determined, and the heat medium with corresponding temperature and flow rate circulates to the heater core 30. Therefore, the circulation path, flow rate, and calorific value of the heater 26 of the heat medium are controlled in consideration of the heat medium temperature from the FC unit 10. The operation of the FC unit 10 is controlled according to the driving state and is independent of the heating requirement.

[0041] <Waste heat requirement of the FC unit>

[0042] When starting in a cold region or when the outside air temperature is very low, etc., when the calorific value in the vehicle is insufficient for the required heating, a waste heat requirement for the FC unit 10 is generated in the control unit 40. The calorific value of the FC unit 10 is increased according to this waste heat requirement, and waste heat corresponding to the waste heat requirement is generated.

[0043] Here, the waste heat requirement is calculated in a predetermined manner as the waste heat of the FC unit 10 required to obtain the required heat in the heater core 30. For example, the waste heat amount of the FC unit 10, that is, the waste heat requirement, is determined according to the heat medium temperature of the pipeline 14-2, the appropriate calorific value of the heater 26, etc.

[0044] Figure 4 It is a flowchart showing the processing of the waste heat requirement for the FC unit 10 regarding heating in the control unit 40.

[0045] First, it is determined whether there is a waste heat requirement for the FC unit 10 with a heating requirement (S11). If the determination in S11 is no (there is no waste heat requirement), no special processing is required, so the normal operation is continued (S12).

[0046] If the determination in S11 is yes, the driving resistance is calculated (S13). First, the current driving resistance of the vehicle is calculated. In this case, the friction coefficient (for example, 25°C) and slope of the current road are obtained from the map data, and the vehicle speed V of the vehicle is obtained. It should be noted that it is preferable to store the frontal projected area of the vehicle, the air resistance coefficient, etc. of the vehicle, and the stored values are used. The driving resistance α at 25°C is calculated by the following formula.

[0047] α = (A)V 2 +C

[0048] Here, A is the air resistance coefficient at 25°C, V is the vehicle speed, and C is the tire rolling resistance at 25°C. It should be noted that the tire rolling resistance C is calculated by the total vehicle weight and the rolling resistance coefficient at 25°C. The rolling resistance coefficient is affected by the road surface conditions (pavement material, wet or dry, etc.), tires (type, air pressure), wheel weight, the state of the wheel bearing (temperature of the grease), etc. However, the rolling resistance coefficient in the standard state (25°C) is used here.

[0049] In addition, as described above, the rolling resistance coefficient varies depending on the road conditions such as the road surface condition and the road slope. In addition, the air resistance coefficient A, the rolling resistance coefficient C, etc. also vary depending on the current environmental conditions such as the temperature outside the vehicle, wind speed, snowfall, and rainfall. Therefore, in this embodiment, the driving resistance β of the air resistance coefficient A' and the rolling resistance C' based on the current road conditions and environmental conditions is calculated by installing various sensors in the vehicle or obtaining information from a server on the cloud. It should be noted that various well-known methods can be used in calculating such driving resistance.

[0050] β=(A')V 2 +C'

[0051] Then, it is determined whether the calculated running resistance β taking into account the environmental conditions is greater than a predetermined value (S14). For example, a standard running resistance for running on a flat standard road is stored, and it is determined whether the running resistance is sufficiently greater than the standard running resistance.

[0052] Therefore, β-α is calculated from the calculated running resistances α and β, and it is determined whether it is larger than a predetermined threshold value. For example, when the threshold value is set to 20N, the following determination is performed.

[0053] β-α>20N

[0054] If the result of S14 is NO, the process proceeds to S12 and normal operation is continued. On the other hand, if the result of S14 is YES, the running resistance is greater than normal, and in this case, the waste heat demand for the FC group 10 is limited (S15).

[0055] When the running resistance is large, the energy required for vehicle running increases, so the load of the FC group 10 also increases, and the heat generation also increases. Therefore, the temperature of the heat medium from the FC group 10 should rise. Therefore, in such a case, the waste heat requirement of the FC group 10 for heating is limited, the inefficient operation of the FC group 10 is suppressed, and the vehicle running is made more efficient. In this way, the drivable distance of the vehicle can be extended.

[0056] Here, in the above example, the running resistance is calculated based on the current running state. However, it is only possible to perform control in accordance with the actual situation by predicting the future running state.

[0057] Figure 5 is a flowchart of the process for predicting the running resistance. Figure 4 The calculation of the running resistance in S13 takes into account not only the current running resistance but also the future running resistance.

[0058] For example, if a destination is set in the navigation device 42 and the vehicle is traveling on the set route, there is a high possibility that the vehicle is traveling on the route, and the future driving resistance can be calculated based on this premise.

[0059] For example, the average values ​​of α and β mentioned above can be calculated for a predetermined time or a predetermined distance (10 minutes or 10 km, etc.) from the current time. It should be noted that the path to the destination can also be set as the object. The map data is stored for each discrete point, and the slope, the friction coefficient of the standard road surface, etc. can directly use the stored data of the object range. In addition, the discrete data can be interpolated to calculate the average value. For environmental data such as temperature (meteorological data), the current data can be used. For example, even if only the slope data is replaced with the average value of the object range, the appropriateness of the processing of the FC waste heat requirement of this embodiment can be sought.

[0060] Furthermore, during route travel, weather forecasts (e.g., changes in temperature and rainfall conditions while traveling to the destination) may be taken into consideration, and optimization calculations may be performed to achieve the most efficient heating, thereby optimizing the utilization of waste heat from the FC group.

[0061] “Limitations on waste heat requirements”

[0062] Figure 6 : is a diagram showing the restriction state of the waste heat requirement for the FC group 10. In this way, until the difference β-α of the running resistance compared to the normal reaches a predetermined threshold value (for example, 20N), the waste heat requirement is set to 100% without restriction. And, in the case where β-α exceeds the threshold value, the waste heat requirement is restricted. As β-α increases, the waste heat requirement is restricted to a lower value, and becomes a sufficiently low value after the predetermined value (it can also be set to 0kW). Through such processing, the operation of heating using the waste heat of the FC group 10 is restricted, and restrictions are imposed on heating. However, since the running resistance is large, the power generation of the FC group 10 increases, and the heat generation during power generation increases. Therefore, even if the waste heat used for heating is not increased, it is highly likely that the required heat can be ensured. In addition, by taking into account the control of the prediction of future driving, the heating amount may be temporarily insufficient, but sufficient heating can be achieved as a whole.

[0063] Here, the limit value of the waste heat requirement can also be limited to the calorific value (kW). In this case, the vertical axis becomes the calorific value (kW), but the characteristics are the same as Figure 6 same.

[0064] As described above, in the present embodiment, the waste heat requirement of the FC stack 10 is restricted in consideration of the current or current and future running resistance. This makes it possible to improve the operation efficiency of the FC stack 10 and maintain a large maximum running distance.

[0065] "other"

[0066] Furthermore, when the running resistance is large and the waste heat of the FC group 10 is large or predicted to be large, the waste heat can be used for heating, so heating by the heater 26 may be limited. This also makes it possible to improve the efficiency of heating and extend the vehicle running distance.

[0067] Description of Reference Numerals

[0068] 10 fuel cell group (FC group), 12 radiator, 14-1, 14-2 pipelines, 14-3 branch pipelines, 16, 24 pumps, 18 rotary valve, 20-1, 20-2, 20-3 branch roads, 22 three-way valve, 26 heater, 30 heater core, 40 control unit, 42 navigation device.

Claims

1. An air conditioning device for a fuel cell vehicle, which utilizes the increased heat generated by the fuel cell stack by changing the operating conditions to reduce the power generation efficiency for heating, The air conditioning device of the fuel cell vehicle comprises: a heater core that circulates heat medium from the fuel cell stack and generates heat through heat exchange with air; and a control unit that calculates a running resistance when the fuel cell vehicle is running on a road based on a road state and an environmental state that affect a running resistance generated when the fuel cell vehicle is running, and controls heat exchange in the heater core based on the calculated running resistance, The control unit restricts operation of the fuel cell stack in which power generation efficiency is reduced and heat generation amount is increased by changing operation conditions when the calculated running resistance is equal to or greater than a predetermined value.

2. The air conditioning device for a fuel cell vehicle according to claim 1, wherein: The road state includes a road gradient of the road on which travel is performed and a friction coefficient of a standard road surface of the road.

3. The air conditioning device for a fuel cell vehicle according to claim 1, wherein: The environmental conditions include the temperature and rainfall conditions during driving.

4. The air conditioning device for a fuel cell vehicle according to claim 1, wherein: The control unit restricts operation of the fuel cell stack to reduce power generation efficiency and increase heat generation by changing operating conditions when the difference between the standard running resistance when the road state and the environmental state are standard and the calculated running resistance is greater than a predetermined value.

5. The air conditioning device for a fuel cell vehicle according to any one of claims 1 to 4, The fuel cell vehicle further comprises a navigation device for guiding the set route. The control unit calculates a running resistance in a set route, and restricts an operation of the fuel cell stack in which power generation efficiency is reduced and heat generation is increased by changing operating conditions based on the running resistance in the set route.

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