Heat control method for electric vehicle and heat control system for electric vehicle

Abstract

To provide a heat control method for an electric vehicle and a heat control system for the electric vehicle that are able to secure an amount of heat required by heat exchange means even when an amount of exhaust heat of an exhaust heat source of the electric vehicle is insufficient.SOLUTION: A heat control method is for an electric vehicle that includes: an exhaust heat circulation passage 1 that circulates a first refrigerant between an exhaust heat source 11 and a first pump 12; and a chiller 21 interposed in the exhaust heat circulation passage 1. The exhaust heat circulation passage 1 is provided with: a first bypass passage 13; and a first switching valve 14 capable of switching a flow state of the first refrigerant between a first state in which the first refrigerant is supplied to the chiller 21 and a second state in which the supply of the first refrigerant to the chiller 21 is stopped and the first refrigerant is caused to flow through the first bypass passage 13. In the heat control method, the first switching valve 14 is set to the first state when a temperature of the first refrigerant is equal to or higher than a predetermined temperature, and the first switching valve 14 is set to the second state when the temperature of the first refrigerant is lower than the predetermined temperature.SELECTED DRAWING: Figure 4

Description

[Technical Field]

[0001] The present invention relates to a thermal control method for an electric vehicle and a thermal control system for an electric vehicle. [Background technology]

[0002] It has been proposed to use exhaust heat from the drive train, such as the motor, to condition the interior of the vehicle (see Patent Document 1). An electric vehicle has a coolant circulation path that cools exhaust heat sources such as the drive train, and a heat pump for conditioning the interior of the vehicle, and it is expected that efficient air conditioning of the vehicle interior will be achieved by exchanging heat between the circulation path and the heat pump using a heat exchanger such as a chiller. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2020-164153 Summary of the Invention [Problem to be solved by the invention]

[0004] However, if the amount of heat exhausted from the exhaust heat source is insufficient, it becomes difficult to ensure the amount of heat required by the heat exchange means.

[0005] The present invention aims to provide a thermal control method for an electric vehicle and a thermal control system for an electric vehicle that can ensure the amount of heat required by a heat exchange means even if the amount of heat exhausted from the exhaust heat source of the electric vehicle is insufficient. [Means for solving the problem]

[0006] A thermal control method for an electric vehicle according to the present invention is a thermal control method for an electric vehicle including an exhaust heat source that releases exhaust heat as the electric vehicle is driven, and a first pumping means that pumps a first refrigerant to the exhaust heat source, a first circulation path that circulates the first refrigerant between the exhaust heat source and the first pumping means, and a first heat exchange means interposed in the first circulation path, wherein the first circulation path is provided with a bypass path that branches off from the upstream side of the first heat exchange means of the first circulation path and joins the first circulation path downstream side of the first heat exchange means so as to be connected in series with the exhaust heat source and the first pumping means and connected in parallel with the first heat exchange means, and a switching means that can switch the flow state of the first refrigerant between a first state in which the first refrigerant is supplied to the first heat exchange means and a second state in which the supply of the first refrigerant to the first heat exchange means is stopped and the first refrigerant is circulated through the bypass path. In this heat control method, the switching means is set to a first state when the temperature of the first refrigerant is equal to or higher than a predetermined temperature, and the switching means is set to a second state when the temperature of the first refrigerant is lower than the predetermined temperature. [Effects of the Invention]

[0007] According to the present invention, when the temperature of the first refrigerant falls below a predetermined temperature, the switching device is set to the second state to stop the supply of the first refrigerant to the first heat exchange device, and heat is efficiently stored in the first refrigerant from the exhaust heat source, thereby ensuring the amount of heat required by the first heat exchange device. Then, when the temperature of the first refrigerant reaches the predetermined temperature, the switching device is switched to the first state to resume the supply of the first refrigerant to the first heat exchange device. Therefore, the amount of heat required by the first heat exchange device can be intermittently ensured and supplied to the first heat exchange device. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 1 is a circuit diagram of a thermal control system for an electric vehicle according to this embodiment when the temperature of a first refrigerant that cools an exhaust heat source is equal to or higher than a predetermined temperature. [Figure 2] FIG. 2 is a circuit diagram of the thermal control system for the electric vehicle of this embodiment when the temperature of the first refrigerant that cools the exhaust heat source is below a predetermined temperature. [Figure 3]FIG. 3 is a circuit diagram of the thermal control system for the electric vehicle of this embodiment when the temperature of the first refrigerant that cools the exhaust heat source reaches the upper limit temperature. [Figure 4] FIG. 4 shows a control flow of the thermal control system for the electric vehicle of this embodiment. [Figure 5] FIG. 5 is a diagram showing the relationship between the pressure of the second refrigerant and the saturation temperature of the second refrigerant. [Figure 6] FIG. 6 is a diagram for explaining the effect of the thermal control system for the electric vehicle of this embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0009] Hereinafter, an embodiment of the present invention will be described with reference to the accompanying drawings.

[0010] [Configuration of thermal control system for electric vehicles] 1 is a circuit diagram of a thermal control system for an electric vehicle of this embodiment when the temperature of a first refrigerant that cools an exhaust heat source 11 is equal to or higher than a predetermined temperature. The thermal control system for an electric vehicle of this embodiment includes an exhaust heat circulation path 1 (first circulation path) that circulates a first refrigerant that recovers exhaust heat generated in the exhaust heat source 11, a heat pump 2 (second circulation path) for air conditioning of the electric vehicle, a heat source circulation path 3 (third circulation path) that supplies heat to a heater core 32 that heats air, a chiller 21 (first heat exchange means) that exchanges heat between the exhaust heat circulation path 1 and the heat pump 2, and a condenser 23 (second heat exchange means) that exchanges heat between the heat pump 2 and the heat source circulation path 3.

[0011] The exhaust heat circulation path 1 circulates a first refrigerant (e.g., water or LLC (Long life Coolant)), the heat pump 2 circulates a second refrigerant (e.g., an alternative refrigerant such as HFC134a), and the heat source circulation path 3 circulates a third refrigerant (e.g., water).

[0012] The exhaust heat circulation path 1 connects the exhaust heat source 11, the chiller 21, and the first pump 12. The exhaust heat circulation path 1 also includes a first bypass path 13, a first switching valve 14, a second bypass path 15, a radiator 16, and a second switching valve 17.

[0013] The exhaust heat source 11 is a drive system that drives the electric vehicle and emits exhaust heat when the electric vehicle is driven. Examples of the exhaust heat source 11 include the drive motor, speed reducer, inverter, battery, charger, DC / DC converter, and junction box of the electric vehicle, but a powertrain (electric powertrain (ePT)) in which at least the drive motor and inverter are combined as an integral unit can also be applied.

[0014] The chiller 21 exchanges heat between the first refrigerant flowing through the exhaust heat circulation path 1 and the second refrigerant flowing through the heat pump 2, thereby heating the second refrigerant.

[0015] First pump 12 (first pumping means) pumps and feeds the first refrigerant discharged from, for example, chiller 21 to exhaust heat source 11 (or radiator 16). First pump 12 is driven by receiving power supply from a battery.

[0016] The first bypass path 13 is a path that branches off from the upstream side of the chiller 21 of the exhaust heat circulation path 1 so as to be connected in series with the exhaust heat source 11 and the first pump 12 and in parallel with the chiller 21, and joins the downstream side of the chiller 21 of the exhaust heat circulation path 1.

[0017] A first switching valve 14 (first switching means) is disposed at a position where the first bypass path 13 of the exhaust heat circulation path 1 branches off (or where the first bypass path 13 joins).

[0018] The first switching valve 14 includes an inlet 141 for the first refrigerant connected to the exhaust heat source 11 side, a first outlet 142 for the first refrigerant connected to the chiller 21 side, and a second outlet 143 for the first refrigerant connected to the first bypass path 13.

[0019] The first switching valve 14 is a valve that can be switched between a first state (Figure 1) in which the inlet 141 and the first outlet 142 are connected and the second outlet 143 is not connected to the inlet 141 and the first outlet 142, and a second state (Figure 2) in which the inlet 141 and the second outlet 143 are connected and the first outlet 142 is not connected to the inlet 141 and the second outlet 143.

[0020] In the exhaust heat circulation path 1, a partial path that is in communication with the chiller 21 and has two junctions with the first bypass path 13 at both ends is connected in parallel to the first bypass path 13. Therefore, instead of the first switching valve 14, a first valve (not shown) may be provided in the partial path, and a second valve (not shown) may be provided in the first bypass path 13. In this arrangement, the first state is achieved by opening the first valve (not shown) and closing the second valve (not shown), and the second state is achieved by closing the first valve (not shown) and opening the second valve (not shown). In the first state, the second valve may be kept open or may be set to a low opening.

[0021] The second bypass path 15 is arranged to bypass the exhaust heat circulation path 1 between the first pump 12 and the exhaust heat source 11, and a radiator 16 is arranged in the second bypass path 15.

[0022] The radiator 16 cools the first refrigerant with outside air supplied while the electric vehicle is running.

[0023] The second bypass path 15 branches off from a predetermined first position (for example, a position between the first pump 12 and the exhaust heat source 11) of the exhaust heat circulation path 1 so as to be connected in series with the exhaust heat source 11, the first pump 12, and the chiller 21, and merges at a second position different from the first position of the exhaust heat circulation path 1 (for example, a position between the first pump 12 and the exhaust heat source 11 and downstream of the first position).

[0024] A second switching valve 17 is disposed in the exhaust heat circulation path 1 at a position that is, for example, the first position (or the second position).

[0025] The second switching valve 17 includes an inlet 171 for the first refrigerant connected to the first pump 12 side, a first outlet 172 for the first refrigerant connected to the exhaust heat source 11 side, and a second outlet 173 for the first refrigerant connected to the radiator 16 side.

[0026] The second switching valve 17 is a valve that can be switched between a third state (Figure 1) in which the inlet 171 and the first outlet 172 are connected and the second outlet 173 is not connected to the inlet 171 and the first outlet 172, and a fourth state (Figure 3) in which the inlet 171 and the second outlet 173 are connected and the first outlet 172 is not connected to the inlet 171 and the second outlet 173.

[0027] In the exhaust heat circulation path 1, a partial path that directly connects the first pump 12 and the exhaust heat source 11 and a second bypass path 15 are connected in parallel. Therefore, instead of the second switching valve 17, a third valve (not shown) may be arranged in the partial path and a fourth valve (not shown) may be arranged in the second bypass path 15. In this arrangement, the third state is achieved by opening the third valve (not shown) and closing the fourth valve (not shown), and the fourth state is achieved by closing the third valve (not shown) and opening the fourth valve (not shown). In the third state, the fourth valve may be set to remain open or to have a lower opening, and in the fourth state, the third valve may be set to remain open or to have a lower opening.

[0028] The heat pump 2 includes a chiller 21, a compressor 22, and a condenser 23.

[0029] The chiller 21 exchanges heat between a low-pressure, low-temperature liquid refrigerant (second refrigerant) and the first refrigerant in the exhaust heat circulation path 1, thereby evaporating the liquid refrigerant (second refrigerant) to generate refrigerant gas (second refrigerant), which is then supplied to the compressor 22.

[0030] Compressor 22 (second pressure-feeding means) compresses the refrigerant gas (second refrigerant) supplied from chiller 21 to generate high-temperature, high-pressure refrigerant gas (second refrigerant), which is then discharged toward condenser 23. Compressor 22 is driven by power supplied from a battery.

[0031] The condenser 23 exchanges heat between the high-temperature, high-pressure refrigerant gas (second refrigerant) and the third refrigerant in the heat source circulation path 3, and cools and condenses the refrigerant gas (second refrigerant) to change it into a high-pressure liquid refrigerant (second refrigerant).

[0032] Although not shown, the heat pump 2 is provided with an expansion valve that rapidly expands the high-pressure liquid refrigerant (second refrigerant) generated in the condenser 23 to produce a low-pressure, low-temperature liquid refrigerant (second refrigerant) and supplies it to the chiller 21. The opening of the expansion valve is controlled (for example, by the controller 7 described below) so that the temperature of the liquid refrigerant (second refrigerant) supplied to the chiller 21 is maintained at a constant temperature (for example, 10°C). Note that an evaporator (not shown) may be provided between the chiller 21 and compressor 22 of the heat pump 2 to reduce the pressure of the refrigerant discharged from the chiller 21, evaporate it, and supply it to the compressor 22.

[0033] The heat source circulation path 3 is provided with a condenser 23, a second pump 31, and a heater core 32.

[0034] Condenser 23 exchanges heat between the third refrigerant circulating through heat source circulation path 3 and the second refrigerant circulating through heat pump 2, thereby heating the third refrigerant.

[0035] The second pump 31 pumps the third refrigerant and is driven by power supplied from a battery.

[0036] This embodiment is integrated with the air conditioning system of the electric vehicle. The air conditioning system includes a duct 41 that supplies air for conditioning to the interior of the vehicle, and a PTC heater 42 (Positive Temperature Coefficient Heater) disposed in the duct 41. A heater core 32 that constitutes the thermal control system of the electric vehicle of this embodiment is disposed within the duct 41.

[0037] The heater core 32 includes tubes through which the third refrigerant flows and heat dissipation fins attached to the tubes, and heats the air to be conditioned when the air comes into contact with the heat dissipation fins.

[0038] The PTC heater 42 generates heat by receiving power from a battery (not shown) and heats the air.

[0039] The first temperature sensor 51 measures the surface temperature of the exhaust heat source 11 .

[0040] The second temperature sensor 52 measures the temperature of the first refrigerant (particularly, the temperature of the first refrigerant immediately before being introduced into the chiller 21).

[0041] The pressure sensor 6 measures the outlet pressure of the chiller 21 on the second refrigerant side (pressure of the second refrigerant).

[0042] The third temperature sensor 53 measures the outlet temperature of the chiller 21 on the second refrigerant side (the actual temperature of the second refrigerant).

[0043] The fourth temperature sensor 54 measures the outlet temperature of the heater core 32 (the temperature of the air immediately after passing through the heater core 32).

[0044] The controller 7 (controller) is configured by one or more computers including, for example, a central processing unit (CPU), a read-only memory (ROM), a random access memory (RAM), and an input / output interface (I / O interface), and is equipped with a program for executing the thermal control method for an electric vehicle according to the present embodiment in accordance with the control flow (FIG. 4) described below. The controller 7 may be a component included in a vehicle controller that controls the drive of the electric vehicle, or may be a component independent of the vehicle controller.

[0045] The controller 7 controls the first pump 12, the first switching valve 14, the second switching valve 17, the compressor 22, the second pump 31, and the PTC heater 42.

[0046] The controller 7 receives input of information on the surface temperature of the exhaust heat source 11 via the first temperature sensor 51, input of information on the temperature of the first refrigerant via the second temperature sensor 52, input of information on the outlet pressure of the second refrigerant of the chiller 21 via the pressure sensor 6, input of information on the outlet temperature of the second refrigerant of the chiller 21 via the third temperature sensor 53, and input of information on the outlet temperature of the heater core 32 via the fourth temperature sensor 54.

[0047] FIG. 1 shows a state in which heat is being supplied to heater core 32. At this time, controller 7 determines that the temperature of the first refrigerant is equal to or higher than a predetermined temperature (third threshold, for example, 30°C), and turns on first pump 12, sets first switching valve 14 to the first state, and sets second switching valve 17 to the third state. Furthermore, as described below, when the actual temperature of the second refrigerant is higher than the saturation temperature of the second refrigerant, controller 7 turns on compressor 22 and turns on second pump 31. This allows the second refrigerant, which does not contain liquid-phase components, to be supplied to compressor 22, thereby reducing the burden on compressor 22. Furthermore, because second pump 31 is turned on, the third refrigerant heated by condenser 23 is supplied to heater core 32, enabling heater core 32 to heat air.

[0048] In addition, the controller 7 compares the target heat quantity when performing the indoor heating with the output heat quantity output from the heater core 32, and if the output heat quantity is lower than the target heat quantity, controls the output of the PTC heater 42 in accordance with the heat quantity that is the difference (second difference) obtained by subtracting the output heat quantity from the target heat quantity.

[0049] Here, the target heat quantity is set to a constant value (for example, 5 kW) or based on the difference between the indoor temperature of the electric vehicle and the heating set temperature of the air conditioning system. The output heat quantity of the heater core 32 is estimated from the outlet temperature of the heater core 32 detected by the fourth temperature sensor 54.

[0050] FIG. 2 illustrates a state after the state in FIG. 1, in which, for example, the amount of exhaust heat from exhaust heat source 11 is low and the temperature of the first refrigerant falls below a predetermined temperature. At this time, controller 7 sets first switching valve 14 to the second state and stops the supply of the first refrigerant to chiller 21. This prevents the first refrigerant from dissipating heat to chiller 21 even when the amount of exhaust heat from exhaust heat source 11 is low, allowing heat to be efficiently stored in the first refrigerant. At this time, the second refrigerant discharged from chiller 21 may contain a liquid phase. Therefore, controller 7 stops compressor 22 to reduce the load on compressor 22. Furthermore, stopping compressor 22 and second pump 31 reduces power consumption.

[0051] Thereafter, when the temperature of the first refrigerant again becomes equal to or higher than the predetermined temperature, the controller 7 sets the first switching valve 14 to the first state and sets the compressor 22 and the second pump 31 to the on state, thereby restarting the supply of heat to the heater core 32. That is, in this embodiment, heat can be intermittently supplied to the heater core 32 even when the amount of exhaust heat from the exhaust heat source 11 is low.

[0052] In the above explanation, it has been explained that first switching valve 14 is set to the first state when the temperature of the first refrigerant is equal to or higher than a predetermined temperature, and is set to the second state when the temperature is below the predetermined temperature. However, in order to prevent control chattering, it is also possible to configure first switching valve 14 to be set to the first state when the temperature of the first refrigerant is equal to or higher than a first predetermined temperature (e.g., 35°C), and to be set to the second state when the temperature of the first refrigerant is below a second predetermined temperature (e.g., 30°C) that is lower than the first predetermined temperature.

[0053] Incidentally, when a drive motor is included as the exhaust heat source 11, torque performance decreases when the temperature of the drive motor drops below a predetermined lower limit temperature. However, if the first refrigerant is circulated in this state to recover exhaust heat from the drive motor, the drive motor will not warm up and torque performance will not be restored.

[0054] Therefore, when the surface temperature of the exhaust heat source 11 falls to a lower limit temperature (for example, 0°C) that is lower than a predetermined temperature (third threshold), the first pump 12 is set to the off state. This allows the warming up of the exhaust heat source 11 to be given priority.

[0055] While the electric vehicle is running, the drive motor can be warmed up by supplying a d-axis current and a q-axis current to the drive motor. When the electric vehicle is stopped, the drive motor can be warmed up by supplying a d-axis current to the drive motor (stopping the q-axis current).

[0056] When heating the room in the state of FIG. 2, heating must be performed only by the PTC heater 42, and therefore the battery bears all of the power consumption of the PTC heater 42 that corresponds to the target heat amount.

[0057] 1, if the amount of heat generated by the heater core 32 is equal to or greater than the target amount of heat, there is no need to use the PTC heater 42, and battery consumption for heating can be avoided. Also, even if the amount of heat generated by the heater core 32 is lower than the target amount of heat, the output of the PTC heater 42 can be set based on the difference obtained by subtracting the amount of heat generated from the target amount of heat, so battery consumption for heating can be reduced compared to when heating is performed using only the PTC heater 42.

[0058] 3 shows a case where the amount of exhaust heat from exhaust heat source 11 is large and the temperature of the first refrigerant reaches an upper limit temperature (e.g., 60°C) that is higher than a predetermined temperature. At this time, controller 7 sets second switching valve 17 to the fourth state. As a result, the first refrigerant is supplied to radiator 16 and cooled by heat exchange with outside air in radiator 16.

[0059] For example, if the amount of heat exhausted from exhaust heat source 11 during normal operation is set to be large relative to the heat capacity of exhaust heat circulation path 1, controller 7 sets second switching valve 17 to the fourth state to cool the first refrigerant using radiator 16, thereby preventing the temperature of the first refrigerant from reaching a predetermined upper limit temperature. On the other hand, if the amount of heat exhausted from exhaust heat source 11 decreases and the temperature of the first refrigerant drops below the predetermined temperature or there is a risk of this happening, controller 7 sets second switching valve 17 to the third state to separate the circulation of the first refrigerant from radiator 16, thereby allowing efficient heat storage in the first refrigerant.

[0060] It is preferable to cover the piping that constitutes the exhaust heat circulation path 1, the heat pump 2, and the heat source circulation path 3 with a heat insulating material. This allows efficient heat storage in the exhaust heat circulation path 1, the heat pump 2, and the heat source circulation path 3. In particular, since the heat source circulation path 3 needs to efficiently release heat to the outside using the heater core 32, it is necessary to improve the insulation of the piping that constitutes the heat source circulation path 3 by sufficiently covering it with a heat insulating material.

[0061] [Control Flow] Fig. 4 shows a control flow of the thermal control system for the electric vehicle of this embodiment. Fig. 5 shows the relationship between the pressure of the second refrigerant and the saturation temperature of the second refrigerant.

[0062] In the initial state, it is assumed that the exhaust heat source 11 (motor, inverter, battery, etc.) of the electric vehicle is operating, and that the driver of the electric vehicle has requested heating from the air conditioning system.

[0063] In step S401, controller 7 sets first pump 12 to the on state and first switching valve 14 to the first state. As a result, the first refrigerant is pumped by first pump 12 and circulates through exhaust heat circulation path 1 in a manner that the first refrigerant flows through exhaust heat source 11 and chiller 21. Then, the first refrigerant recovers exhaust heat from exhaust heat source 11 and dissipates the heat in chiller 21.

[0064] In step S402, controller 7 determines whether the difference (first difference) obtained by subtracting the saturation temperature (Ts) of the second refrigerant from the actual temperature (Ta) of the second refrigerant is greater than a predetermined first threshold (e.g., 2°C), and if the result is NO, proceeds to step S403, and if the result is YES, proceeds to step S409. Here, controller 7 estimates the saturation temperature (Ts) of the second refrigerant by correlating information on the outlet pressure (P) of the second refrigerant of chiller 21 input from pressure sensor 6 with the saturated vapor pressure curve of the second refrigerant shown in Figure 5.

[0065] Here, when the actual temperature (Ta) matches the saturation temperature (Ts), the second refrigerant is a roughly equal mixture of liquid and gas phase components, and when the actual temperature (Ta) is higher than the saturation temperature (Ts), the gas phase components become predominant in the second refrigerant, and when the actual temperature (Ta) is lower than the saturation temperature (Ts), the liquid phase components become predominant in the second refrigerant.

[0066] However, there is a risk that the actual temperature of the second refrigerant (the outlet temperature of the second refrigerant from chiller 21) may be uneven, and in this case, even if the measured actual temperature matches the saturation temperature, the second refrigerant may contain liquid phase components that place a burden on compressor 22.

[0067] Therefore, if the difference (first difference) obtained by subtracting the saturation temperature of the second refrigerant from the actual temperature of the second refrigerant is greater than a first threshold value greater than zero (e.g., 2°C), it is determined that the second refrigerant is predominantly gas phase and contains almost no liquid phase components, and conversely, if the difference is equal to or less than the first threshold value, it is determined that the second refrigerant may contain liquid phase components.

[0068] In step S403, the controller 7 determines that the second refrigerant may contain a liquid phase component that may place a burden on the compressor 22, and turns off the compressor 22 and the second pump 31. This also stops the supply of heat to the heater core 32.

[0069] In step S404, the controller 7 determines whether the surface temperature of the exhaust heat source 11 is higher than a second threshold value (lower limit temperature), and if NO, the process proceeds to step S405, and if YES, the process proceeds to step S406.

[0070] In step S405, the controller 7 stops the first pump 12 and proceeds to step S404. If the first pump 12 has already stopped at the time of step S405, the controller 7 continues to stop the first pump 12. This allows the exhaust heat source 11 to be warmed up preferentially.

[0071] In step S406, the controller 7 sets the first switching valve 14 (flow state of the first refrigerant) to the second state. As a result, the first refrigerant circulates through the exhaust heat circulation path 1 without passing through the chiller 21, thereby storing heat in the chiller 21 without wasting heat.

[0072] In step S407, the controller 7 determines whether the temperature of the first refrigerant is equal to or higher than a third threshold value (predetermined temperature), and if NO, the process proceeds to step S408, and if YES, the process proceeds to step S409.

[0073] In step S408, it is determined whether the rate of increase in the temperature of the first refrigerant is equal to or greater than a predetermined fourth threshold (for example, 1° C. / s), and if YES, the process proceeds to step S407, and if NO, the process proceeds to step S405.

[0074] In step S409, the controller 7 sets the first pump 12 to the ON state and the first switching valve 14 to the first state. This restarts heat exchange between the first refrigerant and the second refrigerant in the chiller 21. Furthermore, the controller 7 sets the compressor 22 and the second pump 31 to the ON state. This restarts the supply of heat to the heater core 32.

[0075] In step S410, controller 7 determines whether the rate of increase of the difference (d / dt·(Ta−Ts)) obtained by subtracting the saturation temperature (Ts) of the second refrigerant from the actual temperature (Ta) of the second refrigerant is greater than or equal to a predetermined fifth threshold (e.g., 0°C / s), and if the answer is YES, proceeds to “END”, and if the answer is NO, proceeds to step S402, determining that there is a risk of liquid phase components reappearing in the second refrigerant.

[0076] [Time chart] FIG. 6 is a diagram for explaining the effect of the thermal control system for the electric vehicle of this embodiment.

[0077] The inventors of the present application investigated the power consumption of air conditioning when the thermal control system of the electric vehicle of this embodiment was implemented and when it was not implemented. Here, when the thermal control system was implemented, the interior was heated by the heater core 32 and the PTC heater 42, and when the thermal control system was not implemented, the interior was heated by only the PTC heater 42.

[0078] As shown in the upper part of FIG. 6, the inventors of the present application investigated the power consumption of the air conditioning when an electric vehicle was accelerated, decelerated, and stopped repeatedly as shown in the graph from time T0 to time T3, increasing the average speed, and finally stopping the vehicle.

[0079] The lower part of FIG. 6 shows a power consumption curve (A) (solid line) when the thermal control system of this embodiment is implemented and a power consumption curve (B) (dashed line) when it is not implemented.

[0080] The power consumption curves (A) and (B) decrease overall over time because the target heat output of the air conditioning system decreases as the indoor temperature rises due to heating.

[0081] In the first time period (1) from time T0 to time T1, the power consumption curve (A) is lower than the power consumption curve (B), in the second time period (2) from time T1 to time T2, the power consumption curve (A) is approximately the same as the power consumption curve (B), and in the third time period (3) from time T2 to time T3, the power consumption curve (A) is lower than the power consumption curve (B). The first time period (1) and the third time period (3) of the power consumption curve (A) indicate that air conditioning is performed by the PTC heater 42 and the heater core 32.

[0082] Here, when comparing the power consumption of power consumption curve (A) and power consumption curve (B), it was found that the power consumption of power consumption curve (A) was improved by about 2 to 4% compared to power consumption curve (B).

[0083] [Effects of this embodiment] According to the thermal control method for an electric vehicle of this embodiment, a first circulation path (exhaust heat circulation path 1) including an exhaust heat source 11 that releases exhaust heat as the electric vehicle is driven, a first pumping means (first pump 12) that pumps and feeds a first refrigerant to the exhaust heat source 11, and including a first heat exchange means (chiller 21) interposed in the first circulation path (exhaust heat circulation path 1), the first circulation path (exhaust heat circulation path 1) including a first heat exchange means (chiller 21) that is connected in series to the exhaust heat source 11 and the first pumping means (first pump 12) and that branches off from the upstream side of the first heat exchange means (chiller 21) of the first circulation path (exhaust heat circulation path 1) so as to be connected in parallel to the first heat exchange means (chiller 21). A thermal control method for an electric vehicle provided with a bypass path (first bypass path 13) that merges with a first heat exchange means (chiller 21) downstream of the first heat exchange means (chiller 21) of the circulation path 1, and a switching means (first switching valve 14) that can switch the flow state of a first refrigerant between a first state in which the first refrigerant is supplied to the first heat exchange means (chiller 21) and a second state in which the supply of the first refrigerant to the first heat exchange means (chiller 21) is stopped and the first refrigerant is circulated through the bypass path (first bypass path 13), wherein the switching means (first switching valve 14) is set to the first state when the temperature of the first refrigerant is equal to or higher than a predetermined temperature (third threshold), and the switching means (first switching valve 14) is set to the second state when the temperature of the first refrigerant falls below the predetermined temperature (third threshold).

[0084] According to the above method, when the temperature of the first refrigerant falls below a predetermined temperature (third threshold), the switching means (first switching valve 14) is set to the second state to stop the supply of the first refrigerant to the first heat exchange means (chiller 21), and heat is efficiently stored in the first refrigerant from the exhaust heat source 11, thereby ensuring the amount of heat required by the first heat exchange means (chiller 21). Then, when the temperature of the first refrigerant reaches the predetermined temperature (third threshold), the switching means (first switching valve 14) is switched to the first state to resume the supply of the first refrigerant to the first heat exchange means (chiller 21). Therefore, the amount of heat required by the first heat exchange means (chiller 21) can be intermittently ensured and supplied to the first heat exchange means (chiller 21).

[0085] In this embodiment, when the temperature of the first refrigerant is equal to or higher than a first predetermined temperature, the switching means (first switching valve 14) is set to a first state, and when the temperature of the first refrigerant falls below a second predetermined temperature that is lower than the first predetermined temperature, the switching means (first switching valve 14) is set to a second state.

[0086] By the above method, chattering in the control of the switching means (first switching valve 14) can be prevented.

[0087] In this embodiment, the system includes a second heat exchange means (condenser 23) different from the first heat exchange means (chiller 21), and a second compression means (compressor 22) that compresses and feeds a second refrigerant to the second heat exchange means (condenser 23), and further includes a second circulation path (heat pump 2) that circulates the second refrigerant between the second heat exchange means (condenser 23) and the second compression means (compressor 22).When the first heat exchange means (chiller 21) is interposed between the first circulation path (exhaust heat circulation path 1) and the second circulation path (heat pump 2) to perform heat exchange between the first refrigerant and the second refrigerant, the second compression means (compressor 22) is set to an on state when the switching means (first switching valve 14) is in a first state, and the second compression means (compressor 22) is set to an off state when the switching means (first switching valve 14) is in a second state.

[0088] By the above method, when the temperature of the first refrigerant is equal to or higher than a predetermined temperature (third threshold), the first refrigerant is supplied to the first heat exchange means (chiller 21). Therefore, the second compression means (compressor 22) of the second circulation path (heat pump 2) can be supplied with a second refrigerant that does not contain liquid phase components, thereby reducing the burden on the second compression means (compressor 22) and ensuring the reliability of the second compression means (compressor 22).

[0089] In this embodiment, the outlet temperature and outlet pressure of the second refrigerant of the first heat exchange means (chiller 21) are measured, the saturation temperature of the second refrigerant is estimated from the outlet pressure, and if the first difference obtained by subtracting the saturation temperature from the outlet temperature is greater than a predetermined threshold (first threshold), the second compression means (compressor 22) continues to be in the on state, and if the first difference is equal to or less than the threshold (first threshold), the second compression means (compressor 22) is set to the off state.

[0090] With the above configuration, after the second pumping means (compressor 22) is set to the on state (driving state), if there is a risk that liquid phase components sufficient to adversely affect the second pumping means will be generated in the second refrigerant, the second pumping means (compressor 22) can be set to the off state (stopped state), thereby further ensuring the reliability of the second pumping means (compressor 22).

[0091] In this embodiment, when the outlet temperature of the second refrigerant of the first heat exchange means (chiller 21) is less than a predetermined temperature change rate (fifth threshold), the outlet temperature and outlet pressure of the second refrigerant of the first heat exchange means (chiller 21) are measured.

[0092] The above method makes it possible to detect early on the risk of liquid phase components being generated in the second refrigerant discharged from the first heat exchange means (chiller 21), thereby improving the safety of the second pressure-transfer means (compressor 22).

[0093] In this embodiment, the system includes a heater core 32 for air conditioning and a third pumping means (second pump 31) that pumps a third refrigerant to the heater core 32, and further includes a third circulation path (heat source circulation path 3) that circulates the third refrigerant between the heater core 32 and the third pumping means (second pump 31).A second heat exchange means (condenser 23) is interposed between the second circulation path (heat pump 2) and the third circulation path (heat source circulation path 3) to perform heat exchange between the second refrigerant and the third refrigerant.When the second pumping means (compressor 22) is in an on state, the third pumping means (second pump 31) is set to an on state, and when the second pumping means (compressor 22) is in an off state, the third pumping means (second pump 31) is set to an off state.

[0094] By using the above method, when the second pumping means (compressor 22) is stopped and the third refrigerant cannot be heated and heat cannot be supplied to the heater core 32, the third pumping means (second pump 31) is stopped, thereby reducing the power consumption of the third pumping means (second pump 31).

[0095] In this embodiment, the vehicle further includes a heat source (PTC heater 42) for air conditioning that generates heat by receiving power from the battery (not shown) of the electric vehicle, and when the heat generation amount of the heater core 32 is lower than the target heat generation amount, the heat generation amount of the heat source (PTC heater 42) is set based on a second difference obtained by subtracting the heat generation amount of the heater core 32 from the target heat generation amount.

[0096] By using the above method, the power consumption of the heat source (PTC heater 42) can be reduced.

[0097] In this embodiment, when air is supplied to the heater core 32 , the heat generation amount of the heater core 32 is estimated based on the temperature of the air immediately after passing through the heater core 32 .

[0098] The above method allows the heat generation amount of the heater core 32 to be estimated in a simple manner.

[0099] In this embodiment, when the temperature of the exhaust heat source 11 is equal to or lower than a predetermined lower limit temperature (second threshold), the first pump 12 is set to the off state.

[0100] With the above configuration, warming up of the exhaust heat source 11 is given priority, and the driving state of the exhaust heat source 11 can be improved.

[0101] In this embodiment, when the temperature of the first refrigerant is below a predetermined temperature (third threshold) and the rate of increase in the temperature of the first refrigerant is below a predetermined threshold (fourth threshold), the first pumping means (first pump 12) is set to an off state.

[0102] By using the above method, the first pumping means (first pump 12) is set to the off state, so that heat can be efficiently stored in the first refrigerant and power consumption by the first pumping means (first pump 12) can be avoided until the temperature of the first refrigerant recovers to a predetermined temperature (third threshold value).

[0103] The thermal control system for an electric vehicle of the present invention includes an exhaust heat source 11 that releases exhaust heat as the electric vehicle is driven, and a first pumping means (first pump 12) that pumps a first refrigerant to the exhaust heat source 11, a first circulation path (exhaust heat circulation path 1) that circulates the first refrigerant, and a first heat exchange means (chiller 21) interposed in the first circulation path (exhaust heat circulation path 1), and the first circulation path (exhaust heat circulation path 1) includes a first bypass path that is connected in series to the exhaust heat source 11 and the first pumping means (first pump 12) and is connected in parallel to the first heat exchange means (chiller 21) and branches off from the upstream side of the first heat exchange means (chiller 21) of the first circulation path (exhaust heat circulation path 1) and joins the downstream side of the first heat exchange means (chiller 21) of the first circulation path (exhaust heat circulation path 1). a first switching means (first switching valve 14) that can switch the flow state of the first refrigerant between a first state in which the first refrigerant is supplied to a first heat exchange means (chiller 21) and a second state in which the supply of the first refrigerant to the first heat exchange means (chiller 21) is stopped and the first refrigerant is circulated through a first bypass path 13, and a control unit (controller 7) that controls the first switching means (first switching valve 14), wherein the control unit (controller 7) sets the first switching means (first switching valve 14) to the first state when the temperature of the first refrigerant is equal to or higher than a predetermined temperature (third threshold), and sets the first switching means (first switching valve 14) to the second state when the temperature of the first refrigerant is lower than the predetermined temperature (third threshold).

[0104] With the above configuration, when the temperature of the first refrigerant falls below a predetermined temperature (third threshold), the switching means (first switching valve 14) is set to the second state to stop the supply of the first refrigerant to the first heat exchange means (chiller 21), and heat is efficiently stored in the first refrigerant from the exhaust heat source 11, thereby ensuring the amount of heat required by the first heat exchange means (chiller 21). Then, when the temperature of the first refrigerant reaches the predetermined temperature (third threshold), the switching means (first switching valve 14) is switched to the first state to resume the supply of the first refrigerant to the first heat exchange means (chiller 21). Therefore, the amount of heat required by the first heat exchange means (chiller 21) can be intermittently ensured and supplied to the first heat exchange means (chiller 21).

[0105] In this embodiment, the system further includes a second bypass path 15 that branches off from a predetermined first position (for example, near the outlet of the first refrigerant of the first pump 12) of the first circulation path (exhaust heat circulation path 1) so as to be connected in series with the exhaust heat source 11, the first pressure-feeding means (first pump 12), and the first heat exchange means (chiller 21) and joins at a second position (for example, near the inlet of the first refrigerant of the exhaust heat source 11) different from the first position of the first circulation path (exhaust heat circulation path 1), a radiator 16 that is arranged in the second bypass path 15 and cools the first refrigerant, and a second switching means (second switching valve 17) that can switch the flow state of the first refrigerant between a third state in which the supply of the first refrigerant to the radiator 16 is stopped and a fourth state in which the first refrigerant is supplied to the radiator 16.

[0106] With the above configuration, for example, when the amount of heat exhausted from exhaust heat source 11 during normal operation is set large relative to the heat capacity of first circulation path (exhaust heat circulation path 1), the control unit (controller 7) sets second switching means (second switching valve 17) to the fourth state to cool the first refrigerant using radiator 16, thereby preventing the temperature of the first refrigerant from reaching a predetermined upper limit temperature. On the other hand, when the amount of heat exhausted from exhaust heat source 11 decreases and the temperature of the first refrigerant drops below a predetermined temperature (third threshold) or there is a risk of this happening, the control unit (controller 7) sets second switching means (second switching valve 17) to the third state to separate the circulation of the first refrigerant from radiator 16, thereby efficiently storing heat in the first refrigerant.

[0107] In this embodiment, the heat pump 2 includes a second heat exchange means (condenser 23) different from the first heat exchange means (chiller 21), and a second compression means (compressor 22) that compresses and feeds a second refrigerant to the second heat exchange means (condenser 23), and circulates the second refrigerant between the second heat exchange means (condenser 23) and the second compression means (compressor 22); The system includes an air conditioning heater core 32, a third pumping means (second pump 31) for pumping a third refrigerant to the heater core 32, and a third circulation path (heat source circulation path 3) for circulating the third refrigerant between the heater core 32 and the third pumping means (second pump 31), and further includes a first heat exchange means (chiller 21) interposed in the first circulation path (exhaust heat circulation path 1) and the second circulation path (heat pump 2) to exchange heat between the first refrigerant and the second refrigerant, and a second heat exchange means (condenser 23) interposed in the third circulation path (heat source circulation path 3) to exchange heat between the second refrigerant and the third refrigerant, and the piping constituting the first circulation path (exhaust heat circulation path 1), the second circulation path (heat pump 2), and the third circulation path (heat source circulation path 3) is covered with a heat insulating material.

[0108] With the above configuration, heat can be efficiently stored in the first circulation path (exhaust heat circulation path 1), the second circulation path (heat pump 2), and the third circulation path (heat source circulation path 3).

[0109] Although the embodiments of the present invention have been described above, the above embodiments merely illustrate some of the application examples of the present invention, and the technical scope of the present invention is not intended to be limited to the specific configurations of the above embodiments. Furthermore, the above embodiments can be combined as appropriate. [Explanation of symbols]

[0110] 1 exhaust heat circulation path, 11 exhaust heat source, 12 first pump, 13 first bypass path, 14 first switching valve, 21 chiller, 7 controller

Claims

1. a first circulation path including: an exhaust heat source that releases exhaust heat as the electric vehicle is driven; and a first pumping means that pumps a first refrigerant to the exhaust heat source, and circulates the first refrigerant between the exhaust heat source and the first pumping means; a first heat exchange means interposed in the first circulation path, The first circulation path includes: a bypass path that branches off from the first circulation path at an upstream side of the first heat exchange means so as to be connected in series to the exhaust heat source and the first pumping means and to be connected in parallel to the first heat exchange means, and that joins the first circulation path at a downstream side of the first heat exchange means; a switching means for switching a flow state of the first refrigerant between a first state in which the first refrigerant is supplied to the first heat exchange means and a second state in which the supply of the first refrigerant to the first heat exchange means is stopped and the first refrigerant is circulated through the bypass path, A thermal control method for an electric vehicle, comprising: setting the switching means to the first state when the temperature of the first refrigerant is equal to or higher than a predetermined temperature; and setting the switching means to the second state when the temperature of the first refrigerant is lower than the predetermined temperature.

2. 2. The thermal control method for an electric vehicle according to claim 1, wherein the switching means is set to the first state when the temperature of the first refrigerant is equal to or higher than a first predetermined temperature, and the switching means is set to the second state when the temperature of the first refrigerant falls below a second predetermined temperature that is lower than the first predetermined temperature.

3. a second heat exchange means different from the first heat exchange means, and a second pumping means for pumping a second refrigerant to the second heat exchange means, and further including a second circulation path for circulating the second refrigerant between the second heat exchange means and the second pumping means; In a case where the first heat exchange means is interposed in the first circulation path and the second circulation path to exchange heat between the first refrigerant and the second refrigerant, 2. The thermal control method for an electric vehicle according to claim 1, wherein the second pumping means is set to an ON state when the switching means is in the first state, and the second pumping means is set to an OFF state when the switching means is in the second state.

4. measuring an outlet temperature and an outlet pressure of the second refrigerant from the first heat exchange means; estimating a saturation temperature of the second refrigerant from the outlet pressure; When a first difference obtained by subtracting the saturation temperature from the outlet temperature is greater than a predetermined threshold value, the second pumping means is kept in an on state; The thermal control method for an electric vehicle according to claim 3, wherein the second pumping device is set to an off state when the first difference is equal to or smaller than the threshold value.

5. The thermal control method for an electric vehicle according to claim 4, wherein the outlet temperature and the outlet pressure of the second refrigerant of the first heat exchange means are measured when the outlet temperature of the second refrigerant of the first heat exchange means is less than a predetermined temperature change rate.

6. a heater core for air conditioning; and a third pumping means for pumping a third refrigerant to the heater core, and further including a third circulation path for circulating the third refrigerant between the heater core and the third pumping means; In a case where the second heat exchange means is interposed in the second circulation path and the third circulation path to exchange heat between the second refrigerant and the third refrigerant, 6. The thermal control method for an electric vehicle according to claim 3, wherein the third pumping means is set to an on state when the second pumping means is in an on state, and the third pumping means is set to an off state when the second pumping means is in an off state.

7. a heat source for the air conditioning that generates heat by receiving power from a battery of the electric vehicle; 7. The thermal control method for an electric vehicle according to claim 6, wherein when the heat generation amount of the heater core is lower than the target heat generation amount, the heat generation amount of the heat source is set based on a second difference obtained by subtracting the heat generation amount of the heater core from the target heat generation amount.

8. 8. The thermal control method for an electric vehicle according to claim 7, wherein, when air is supplied to the heater core, the heat generation amount of the heater core is estimated based on the temperature of the air immediately after passing through the heater core.

9. The thermal control method for an electric vehicle according to claim 1, wherein the first pumping means is set to an off state when the temperature of the exhaust heat source is equal to or lower than a predetermined lower limit temperature.

10. 2. The thermal control method for an electric vehicle according to claim 1, wherein the first pumping means is set to an off state when the temperature of the first refrigerant is lower than the predetermined temperature and the rate of increase in the temperature of the first refrigerant is lower than a predetermined threshold.

11. a first circulation path including: an exhaust heat source that releases exhaust heat as the electric vehicle is driven; and a first pumping means that pumps a first refrigerant to the exhaust heat source, and through which the first refrigerant circulates; a first heat exchange means interposed in the first circulation path, The first circulation path includes: a first bypass path that branches off from the first circulation path at an upstream side of the first heat exchange means and joins the first circulation path at a downstream side of the first heat exchange means so as to be connected in series to the exhaust heat source and the first pumping means and to be connected in parallel to the first heat exchange means; a first switching means capable of switching a flow state of the first refrigerant between a first state in which the first refrigerant is supplied to the first heat exchange means and a second state in which the supply of the first refrigerant to the first heat exchange means is stopped and the first refrigerant is circulated through the first bypass path; A thermal control system for an electric vehicle further including a control unit that controls the first switching means, The control unit A thermal control system for an electric vehicle that sets the first switching device to the first state when the temperature of the first refrigerant is equal to or higher than a predetermined temperature, and sets the first switching device to the second state when the temperature of the first refrigerant is lower than the predetermined temperature.

12. a second bypass path that branches off from a predetermined first position of the first circulation path so as to be connected in series to the exhaust heat source, the first pumping means, and the first heat exchange means, and that joins the first circulation path at a second position different from the first position; a radiator disposed in the second bypass path and configured to cool the first refrigerant; 12. The thermal control system for an electric vehicle according to claim 11, further comprising: second switching means capable of switching a flow state of the first refrigerant between a third state in which the supply of the first refrigerant to the radiator is stopped and a fourth state in which the first refrigerant is supplied to the radiator.

13. a second circulation path including a second heat exchange means different from the first heat exchange means and a second pumping means that pumps a second refrigerant to the second heat exchange means, and circulating the second refrigerant between the second heat exchange means and the second pumping means; a third circulation path including a heater core for air conditioning and a third pumping means for pumping a third refrigerant to the heater core, and circulating the third refrigerant between the heater core and the third pumping means; When the first heat exchange means is interposed in the first circulation path and the second circulation path and performs heat exchange between the first refrigerant and the second refrigerant, and the second heat exchange means is interposed in the third circulation path and performs heat exchange between the second refrigerant and the third refrigerant, The thermal control system for an electric vehicle according to claim 12, wherein pipes constituting the first circulation path, the second circulation path, and the third circulation path are covered with a heat insulating material.

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