Heating control device and control program, fluid heating unit, heating cycle device and vehicle air conditioner equipped therewith

Abstract

[Problem] The purpose of the present disclosure is to provide a heating control device capable of performing control with small fluctuations in temperature with respect to the target temperature and such that a target temperature is rapidly reached, and also to provide a heating cycle device and a vehicle air conditioner equipped therewith. [Solution] A heating control device 6 according to the present disclosure controls a transistor 5 that supplies power by switching operation to a heater 4 that heats a coolant, the heating control device adjusting the heating amount of the heater on the basis of a heating amount control profile that has a decreasing portion in which the heating amount decreases as the coolant temperature rises, the decreasing portion having a first decreasing portion and a second decreasing portion each having a negative slope, the first decreasing portion and the second decreasing portion having the same heating amount at the target temperature, the first decreasing portion having a first region and a second region, and the slope at any temperature within the second region being negative with respect to the slope at any temperature within the first region.

Description

Heating control device and control program, fluid heating unit, heating cycle device, and vehicle air conditioning device equipped with the same

[0001] The present disclosure relates to a heating control device and a control program, a fluid heating unit, a heating cycle device, and a vehicle air conditioner including the same.

[0002] Conventionally, a vehicle air conditioner using a hot water heating system that uses hot water for heating has been known (see, for example, Patent Document 1). The vehicle air conditioner of Patent Document 1 includes a first switch and a second switch, and by setting the target temperature of the hot water when activated by the second switch to a value lower than the target temperature of the hot water when activated by the first switch, a comfortable heating temperature can be obtained when heating when the temperature inside the vehicle cabin is high.

[0003] Furthermore, as a heater for a hot water heating device, a fluid heating unit that heats a fluid by an electric heater has been disclosed (see, for example, Patent Document 2).

[0004] As a method for controlling the amount of power supplied to an electric heater, a method is known in which DC power obtained from a battery is supplied by duty-controlling it using an inverter (see, for example, Patent Document 3).

[0005] Japanese Patent Laid-Open No. 10-258630 Japanese Patent Laid-Open No. 2017-215084 Japanese Patent Laid-Open No. 2003-335127

[0006] In recent years, electric vehicles (EVs) that run solely on electric motors, hybrid electric vehicles (HEVs) that run on multiple power sources including electric motors and internal combustion engines, and vehicles that run on electric motors that are driven by electricity generated solely by internal combustion engines have become widespread.

[0007] Since electric vehicles do not have engines, the total coolant volume in the coolant loop can be less than 10 liters, which is less than that of engine-equipped vehicles. The coolant flow rate in the coolant loop, while variable, is approximately 10 liters per minute, meaning the entire fluid circulates in less than one minute. Therefore, if temperature hunting occurs at the outlet of the fluid heating unit, the effect of hunting is likely to extend throughout the entire path due to the small total coolant volume. Therefore, there is a need for stricter temperature control and temperature stabilization than in engine-equipped vehicles.

[0008] In addition, in the case of hybrid vehicles or vehicles that have an internal combustion engine but can be driven by an electric motor, the total amount of coolant is larger than that of electric vehicles, but there is a demand to reduce the total vehicle weight by reducing the amount of coolant, so the total amount of coolant is on the decline. For this reason, if temperature hunting occurs at the heater outflow point, the effect of hunting is likely to extend to the entire route.

[0009] For example, in Figure 2 of the vehicle air conditioning device of Patent Document 1, the temperature change of the hot water is controlled to within ±5°C of the target temperature, but in a vehicle with a small total amount of coolant, it is necessary to make the temperature change smaller, for example, to within ±1°C of the target temperature.

[0010] The present disclosure aims to provide a heating control device and control program, a fluid heating unit, a heating cycle device, and a vehicle air conditioning device equipped with the same, which can reach a target temperature quickly and control the temperature with little fluctuation relative to the target temperature.

[0011] The heating control device according to the present invention is a heating control device that controls a transistor that supplies power by a switching operation to a heater that generates heat when energized and heats a coolant that is supplied to a radiator mounted on a vehicle air conditioner, and the heating control device controls the switching operation of the transistor based on a heat amount control profile, and adjusts the amount of heat generated by the heater by changing the on-off duty ratio of the transistor, and the heat amount control profile is a function that indicates the relationship between the temperature of the coolant and the amount of heat generated by the heater ... The heating amount control profile has a decreasing section in which the heating amount decreases, the decreasing section having a first decreasing section when the temperature is in a temperature range below the target temperature and a second decreasing section when the temperature is in a temperature range above the target temperature, the first decreasing section and the second decreasing section have the same heating amount at the target temperature, both the first decreasing section and the second decreasing section have negative slopes in the function, the first decreasing section has a first region and a second region that is higher in temperature than the first region, and the slope of the heating amount control profile at any temperature within the second region is more negative than the slope of the heating amount control profile at any temperature within the first region.

[0012] In the heating control device according to the present invention, the decreasing portion may be a curve having an inflection point, and the temperature at the inflection point may coincide with the target temperature.

[0013] In the heating control device according to the present invention, the decreasing portion is a curve having an inflection point, and the temperature at the inflection point may be higher than the target temperature.

[0014] In the heating control device of the present invention, the decreasing portion is a curve having an inflection point, the temperature at the inflection point is lower than the target temperature, and the second region is in a region lower in temperature than the inflection point.

[0015] In the heating control device according to the present invention, the first region and the second region may be linear functions having different slopes in the functions.

[0016] In the heating control device according to the present invention, the decreasing portion may be a curve that does not have an inflection point.

[0017] In the heating control device of the present invention, the heating amount control profile includes a form having a constant portion on the lower temperature side than the first decreasing portion, in which the heating amount remains constant even when the temperature rises from the lower temperature side to the higher temperature side.

[0018] In the heating control device according to the present invention, it is preferable that the second decrease section has a heat radiation amount corresponding region on the higher temperature side than the target temperature, in which the heat amount is maintained at a predetermined heat amount.

[0019] The fluid heating unit of the present invention comprises a heater that generates heat when current is applied to heat the coolant, a transistor that supplies power to the heater by switching operation, and a heating control device of the present invention, wherein the heating control device controls the switching operation of the transistor.

[0020] The heating cycle device of the present invention comprises a circulation flow path, a coolant filled in the circulation flow path, a pump that circulates the coolant through the circulation flow path, a fluid heating unit of the present invention that regulates the temperature of the coolant, and a radiator that dissipates heat from the coolant, and is characterized in that the coolant is heated by energizing the heater in the fluid heating unit using the transistor.

[0021] The vehicle air conditioning system of the present invention is a vehicle air conditioning system equipped with the heating cycle device of the present invention and mounted on a vehicle, wherein the vehicle is capable of running using an electric motor, the vehicle air conditioning system has a temperature control unit that adjusts the temperature of the air supplied to the vehicle cabin, and the radiator is a hot water heat exchanger arranged inside the temperature control unit.

[0022] The control program according to the present invention is characterized in that it causes the heating control device according to the present invention to execute a process for controlling the switching operation of the transistor based on the heat amount control profile.

[0023] According to the present disclosure, it is possible to provide a heating control device and control program, a fluid heating unit, a heating cycle device, and a vehicle air conditioning device equipped with the same, which can reach a target temperature quickly and control the temperature with little fluctuation relative to the target temperature.

[0024] 1 is a block diagram showing an example of a fluid heating unit, a heating cycle device, and a vehicle air conditioner including the same according to the present embodiment; FIG. 2 is a diagram showing a first example of a heating amount control profile; FIG. 3 is a diagram showing a second example of a heating amount control profile; FIG. 4 is a diagram showing a third example of a heating amount control profile; FIG. 5 is a diagram showing a fifth example of a heating amount control profile; FIG. 6 is a diagram showing a first example of a profile excluded from the heating amount control profile; FIG. 7 is a diagram showing a second example of a profile excluded from the heating amount control profile; FIG. 8 is a diagram showing a third example of a profile excluded from the heating amount control profile; and FIG. 9 is a diagram showing a fourth example of a profile excluded from the heating amount control profile. It is a diagram showing an example of duty control of a heating cycle device, where (a) shows duty control in a constant portion, (b) shows duty control at an arbitrary temperature in a decreasing portion, and (c) shows duty control at an arbitrary temperature in a heat radiation amount corresponding region. It is a diagram showing the relationship between heating time and coolant temperature in Example 1; it is a diagram showing the relationship between heating time and coolant temperature in Comparative Example 1; it is a diagram showing the relationship between heating time and coolant temperature in Comparative Example 2.

[0025] Hereinafter, one aspect of the present invention will be described with reference to the accompanying drawings. The embodiments described below are examples of the present invention, and the present invention is not limited to the following embodiments. Note that components with the same reference numerals in this specification and drawings indicate the same components. Various modifications may be made as long as the effects of the present invention are achieved.

[0026] 1 is a block diagram showing an example of a heating cycle device and a vehicle air conditioner including the same according to the present embodiment. A heating control device 6 according to the present embodiment controls a transistor 5, by switching, to supply power to a heater 4, which generates heat when energized and heats a coolant supplied to a radiator 7 mounted on a vehicle air conditioner 900. The heating control device 6 controls the switching operation of the transistor 5 based on a heat amount control profile 100 (100A to 100E) shown in FIGS. 2 to 6 to change the on-off duty ratio of the transistor 5 to adjust the amount of heat generated by the heater 4. The heat amount control profile 100 (100A to 100E) is a function showing the relationship between the coolant temperature T and the amount of heat generated by the heater, as shown in FIGS. 2 to 6. As the temperature T rises from the low temperature side to the high temperature side across the coolant target temperature Tt, the amount of heat generated by the heater 4 is adjusted. The heat amount control profile 100 has a decreasing section 110 in which the heat amount E decreases as the temperature T decreases, the decreasing section 110 having a first decreasing section 111 when the temperature T is in a temperature range equal to or lower than the target temperature Tt, and a second decreasing section 112 when the temperature T is in a temperature range equal to or higher than the target temperature Tt, the first decreasing section 111 and the second decreasing section 112 having the same heat amount E at the target temperature Tt, both the first decreasing section 111 and the second decreasing section 112 having a negative slope in the function, the first decreasing section 111 having a first region 111A and a second region 111B that is higher in temperature than the first region 111A, and the slope of the heat amount control profile 100 (100A to 100E) at an arbitrary temperature within the second region 111B is more negative than the slope of the heat amount control profile 100 (100A to 100E) at an arbitrary temperature within the first region 111A.

[0027] The fluid heating unit 10 of this embodiment includes a heater 4 that generates heat when current is applied to heat the coolant, a transistor 5 that supplies power to the heater 4 through switching operations, and a heating control device 6 of this embodiment, where the heating control device 6 controls the switching operations of the transistor 5.

[0028] In the fluid heating unit 10, the transistor 5 supplies power to the heater 4, which generates heat, thereby heating the coolant supplied to the radiator 7 of the vehicle air conditioner. At this time, the heating control device 6 controls the switching operation of the transistor 5 based on the heating amount control profile 100 (100A to 100E), and changes the on-off duty ratio of the transistor 5 to adjust the amount of heat generated by the heater 4, thereby controlling the temperature of the coolant.

[0029] The heating cycle device 1 of this embodiment includes a circulation flow path 2, a coolant filled in the circulation flow path 2, a pump 3 that circulates the coolant through the circulation flow path 2, a fluid heating unit 10 of this embodiment that regulates the temperature of the coolant, and a radiator 7 that dissipates heat from the coolant, and the coolant is heated by energizing a heater 4 in the fluid heating unit 10 using a transistor 5.

[0030] The heating cycle device 1 is a device that generates warm air for heating in a vehicle air conditioning system by exchanging heat between coolant whose temperature has been adjusted by a fluid heating unit 10 and air passing through a radiator 7 .

[0031] The circulation flow path 2 includes a pipe 12 connecting the coolant outlet of the radiator 7 to the pump 3, and a pipe 13 connecting the pump 3 to the tank inlet 10b. The coolant is sent by the pump 3 through a pipe 11 connecting the coolant inlet of the radiator 7 to the outlet 10a of a tank (not shown) that houses a heater 4, and is introduced into a heating chamber in the tank (not shown) from the inlet 10b via the pipe 13, where it is heated by the heater 4 built into the tank. The heated coolant is then discharged from the tank outlet 10a and sent to the radiator 7 through the pipe 11, where it radiates heat and warms the air for air conditioning. The coolant that passes through the radiator 7 is sucked into the pump 3 through the pipe 12 and circulated.

[0032] The coolant (not shown) is liquid at room temperature and is a heat transfer medium such as water dissolved with ethylene glycol or glycerin.

[0033] Like the fluid control unit described in Patent Document 2, the fluid heating unit 10 includes a heater 4, a tank (not shown) that houses the heater 4, and a transistor 5 arranged on the upper wall of the tank.

[0034] The heater 4 is an electric heating element that generates heat when electricity is applied, and is not particularly limited; for example, a sheathed heater in which nichrome wire is wrapped in a metal pipe is used. The tank has a heating chamber through which coolant flows and which houses the heater 4. The heating chamber receives the coolant before heating through an inlet 10b, and discharges the heated coolant through an outlet 10a. The heating chamber preferably has a temperature sensor 50 near the outlet 10a that detects the temperature T of the heated coolant. It is more preferable that the temperature sensor 50 be provided at the outlet 10a.

[0035] The transistor 5 is preferably, for example, an insulated gate bipolar transistor (IGBT). The transistor 5 is electrically connected to the battery 8. The transistor 5 is also electrically connected to the control device 6 and performs a switching operation in response to a command signal from the heating control device 6. The transistor 5 controls the supply of power to the heater 4 through its switching operation. By changing the on-off duty ratio of the transistor 5, the amount of heat generated by the heater 4 can be adjusted, and the amount of heat provided to the coolant can be adjusted. The fluid heating unit 10 is configured to have at least the heater 4, the transistor 5, the heating control device 6, and electrical wiring 51 that connects these elements to the battery 8 and forms an electrical circuit.

[0036] The heating control device 6 controls the switching operation of the transistor 5 based on the heating amount control profile 100 (100A to 100E).

[0037] The control program according to this embodiment causes the heating control device 6 according to this embodiment to execute a process for controlling the switching operation of the transistor 5 based on the heat amount control profile (100 (100A to 100E)). The heating control device 6 has a memory unit (not shown) and functions as a heating control device by executing a control program read from the memory unit. Execution of the control program includes, for example, the following process. First, the current temperature T of the coolant is detected, and the heat amount control profile (100 (100A to 100E)) is applied to read the "heat amount E by the heater 4" corresponding to the current temperature T. Next, duty control is performed as shown in FIG. 11 to control the transistor 5 so that the "heat amount E corresponding to the current temperature T" is applied to the heater 4.

[0038] The radiator 7 is a hot water heat exchanger.

[0039] Instead of being installed in the fluid heating unit 10, the temperature sensor 50 may be installed in the piping 11 in the circulation circuit 2 that connects the outlet 10a of the tank (not shown) that houses the heater 4 to the coolant inlet of the radiator 7.

[0040] As shown in FIGS. 2 to 6, the heat amount control profile 100 (100A to 100E) is a function that indicates the relationship between the coolant temperature T and the heat amount E generated by the heater 4. In FIGS. 2 to 6, the heat amount control profile 100 (100A to 100E) is displayed as a graph with the coolant temperature T on the horizontal axis and the heat amount E generated by the heater 4 on the vertical axis. The coolant temperature T is preferably the temperature of the coolant discharged from the outlet 10a of the fluid heating unit 10, and is expressed in units of °C, for example. The heat amount E generated by the heater 4 is a value that is adjusted, for example, by the on-off duty ratio of the transistor 5, and is expressed in units of KW / h, for example.

[0041] The decrease portion 110 is a portion where the amount of heat E decreases as the temperature T rises from the low temperature side to the high temperature side across the target temperature Tt of the coolant. In Figures 2 to 6, the decrease portion 110 is a temperature range from the temperature T1 at which the amount of heat E begins to decrease to the temperature Te at which the amount of heat E approaches zero or to a temperature (not shown) at which the amount of heat E becomes zero. The temperature T1 at which the decrease portion 110 starts is preferably {target temperature Tt} - 10°C, and more preferably {target temperature Tt} - 8°C. The target temperature Tt is, for example, 80 to 85°C.

[0042] The first decrease portion 111 is a temperature range of the decrease portion 110 from temperature T1, at which the amount of heat E begins to decrease, to a target temperature Tt or lower. The first decrease portion 111 has a first region 111A and a second region 111B that is higher in temperature than the first region 111A. The boundary between the first region 111A and the second region 111B is not particularly limited, and in FIG. 2, as an example, the boundary is set to temperature T3, which bisects the range between temperature T1, at which the decrease portion 110 begins, and the target temperature Tt, but any temperature may be used.

[0043] The second decreasing section 112 is a temperature range in the decreasing section 110 from the target temperature Tt to a temperature Te at which the heating amount E approaches zero or a temperature (not shown) at which the heating amount E becomes zero.

[0044] As shown in FIGS. 2 to 6 , the first decrease section 111 and the second decrease section 112 have the same heating amount E at the target temperature Tt. For this reason, profiles 200 and 201 in which the heating amount decreases at the target temperature Tt, as shown in FIGS. 7 and 8 , are excluded from the heating amount control profile 100. FIG. 7 shows a simple on-off control, while FIG. 8 is a modified example of FIG. 7 . In the profiles 200 and 201 shown in FIGS. 7 and 8 , the heating amount E decreases rapidly at the target temperature Tt, resulting in large fluctuations in temperature relative to the target temperature. This is because the coolant dissipates heat in the radiator 7, and if the heating amount were suddenly set to "zero" just because the coolant has risen in temperature and reached the target temperature Tt, the coolant temperature T would drop rapidly from the target temperature.

[0045] As shown in FIGS. 2 to 6 , the first decrease portion 111 and the second decrease portion 112 both have negative slopes in the function, and the slope of the heat amount control profile 100 (100A-100E) at any temperature in the second region 111B is more negative than the slope of the heat amount control profile 100 (100A-100E) at any temperature in the first region 111A. This allows the target temperature to be reached quickly and reduces temperature fluctuations relative to the target temperature. For example, as shown in FIG. 9 , a profile 202 with a constant slope in the first decrease portion 111 and a profile 203 with a slope at any temperature in the second region 111B that is less negative than the slope at any temperature in the first region 111A are excluded from the heat amount control profile 100. Profiles 202 and 203 such as those shown in FIGS. 9 and 10 slow the temperature rise rate and prevent the target temperature from being reached quickly.

[0046] In the heating cycle device according to this embodiment, as shown in Figures 2 to 6, the heating amount control profile 100 (100A to 100E) includes a form having a constant section 120 on the lower temperature side than the first decreasing section 111, in which the heating amount E remains constant even when the temperature T rises from the lower temperature side to the higher temperature side.

[0047] In the heating cycle device according to this embodiment, as shown in FIGS. 2 to 6 , the second decrease section 112 preferably includes a heat dissipation amount corresponding region 112A above the target temperature Tt, which maintains the heat amount E at a predetermined value. The heat dissipation amount corresponding region 112A is a region in which the heat amount E approaches but does not reach zero. The end time Te of the heat dissipation amount corresponding region 112A is preferably {target temperature Tt + 8°C} ± 1°C. The start time T2 of the heat dissipation amount corresponding region 112A is preferably {target temperature Tt + 4°C} ± 1°C, for example. The radiator 7 dissipates heat. If the heat amount were suddenly set to "zero" just because the temperature rose above the target temperature Tt, the coolant temperature T would fall below the target temperature, leading to temperature hunting. However, by providing the heat dissipation amount corresponding region 112A, temperature hunting can be suppressed.

[0048] In the heat amount control profiles 100 (100A to 100E), the temperature T at which the heat amount E becomes 0 is preferably 90° C. If the temperature exceeds 90° C., problems may occur, such as unintended precipitation of components dissolved in the coolant or reduced thermal conductivity due to the generation of bubbles at the interface between the coolant and the heat transfer wire.

[0049] Next, examples of each of the heat amount control profiles 100 (100A to 100E) will be described in more detail.

[0050] FIG. 2 is a diagram showing a first example of a heating amount control profile. In the heating cycle device according to this embodiment, as shown in FIG. 2, the decreasing portion 110 is a curve having an inflection point P, and the temperature T at the inflection point P coincides with the target temperature Tt. The first example of the heating amount control profile 100 (100A) can reach the target temperature Tt within 15 minutes, for example, and can control the temperature relative to the target temperature Tt to within a range of {target temperature Tt} ±1°C, for example. Furthermore, because the temperature T at the inflection point P coincides with the target temperature Tt, temperature fluctuations relative to the target temperature Tt can be controlled to be smaller.

[0051] FIG. 3 is a diagram showing a second example of a heat amount control profile. In the heating cycle device according to this embodiment, as shown in FIG. 3 , the decreasing portion 110 is a curve having an inflection point P, and the temperature T at which the inflection point P occurs includes a form in which the temperature T is higher than the target temperature Tt. The temperature T at which the inflection point P occurs is preferably greater than {target temperature Tt} + 0 degrees and less than or equal to +4°C, and more preferably greater than {target temperature Tt} + 1°C or greater and less than or equal to +2°C. If the temperature T at which the inflection point P occurs exceeds {target temperature Tt} + 4°C, the coolant may be overheated relative to the target temperature. The second example of the heat amount control profile 100 (100B) can reach the target temperature Tt within, for example, 15 minutes and can control the temperature relative to the target temperature Tt to within, for example, the range of {target temperature Tt} ± 1°C. Furthermore, since the temperature T at which the inflection point P occurs is higher than the target temperature Tt, it becomes easy to set the amount of heating E by the heater to a relatively large value when the coolant temperature T is at the target temperature Tt, and this makes it possible to suitably control the temperature fluctuation relative to the target temperature Tt to a small value, particularly in a vehicle air conditioning system 900 in which the amount of heat dissipated by the radiator 7 is relatively large.

[0052] FIG. 4 is a diagram showing a third example of a heating amount control profile. In the heating cycle device according to this embodiment, as shown in FIG. 4 , the decreasing portion 110 is a curve having an inflection point P, and the temperature T at which the inflection point P occurs is lower than the target temperature Tt. The second region 111B includes a configuration in which the temperature T at which the inflection point P occurs is in a region lower than the inflection point P. The temperature T at which the inflection point P occurs is preferably equal to or higher than the target temperature Tt −4° C. and lower than 0° C., and more preferably equal to or higher than the target temperature Tt −1° C. and lower than the target temperature Tt −2° C. If the temperature T at which the inflection point P occurs is lower than the target temperature Tt −4° C., the time required to reach the target temperature Tt may be longer. In the third example of the heating amount control profile 100 (100C), the first decreasing portion 111 includes a third region 111C, which is a region higher than the temperature at which the inflection point P occurs. The third example of the heating amount control profile 100 (100C) can reach the target temperature Tt within, for example, 15 minutes and can control the temperature relative to the target temperature Tt to within a range of, for example, {target temperature Tt} ±1° C. Furthermore, because the temperature T at the inflection point P is lower than the target temperature Tt, it becomes easy to set the heating amount E by the heater to a relatively small value when the coolant temperature T is at the target temperature Tt. This makes it possible to suitably control the temperature fluctuation relative to the target temperature Tt to a small value, particularly in a vehicle air conditioning device 900 in which the amount of heat radiated by the radiator 7 is relatively small.

[0053] 5 is a diagram showing a fourth example of a heating amount control profile. In the heating cycle device according to this embodiment, as shown in FIG. 5, the first region 111A and the second region 111B include a form in which the functions are both linear functions with different slopes. The fourth example of the heating amount control profile 100 (100D) can reach the target temperature Tt within, for example, 15 minutes and control the temperature relative to the target temperature Tt to within, for example, the range of {target temperature Tt} ± 1°C.

[0054] 6 is a diagram showing a fifth example of a heating amount control profile. In the heating cycle device according to this embodiment, as shown in FIG. 6, the decreasing section 110 includes a curve that does not have an inflection point. The fifth example of the heating amount control profile 100 (100E) can reach the target temperature Tt within, for example, 15 minutes and control the temperature relative to the target temperature Tt to within, for example, the range of {target temperature Tt} ± 1°C.

[0055] 11 is a diagram showing an example of duty control of a heating cycle device, where (a) shows duty control in a constant portion, (b) shows duty control at an arbitrary temperature in a decreasing portion, and (c) shows duty control at an arbitrary temperature in the heat radiation amount corresponding region. The duty ratio in the decreasing portion 110 (shown in FIGS. 2 to 6) is set smaller than the duty ratio in the constant portion 120 (shown in FIGS. 2 to 6). In the decreasing portion 110, the duty ratio is gradually reduced over time to adjust the amount of heat E generated by the heater 4, as shown in FIGS. 2 to 6. Alternatively, in the decreasing portion 110, the duty ratio is gradually reduced as the coolant temperature rises, to adjust the amount of heat E generated by the heater 4, as shown in FIGS. 2 to 6.

[0056] The duty control period is not particularly limited, but is preferably 0.015 to 0.025 seconds, for example. In Figures 11(a) to 11(c), the duty control period is 0.02 seconds as an example. The duty ratio in the constant portion 120 (shown in Figures 2 to 6) is not particularly limited, but is preferably 60% or more and 100% or less. In Figure 11(a), as an example, the duty ratio in the constant portion 120 (shown in Figures 2 to 6) is 80%. The duty ratio at any temperature in the decreasing portion 110 (shown in Figures 2 to 6) is not particularly limited, but is preferably 30% or more and less than 60%. In Figure 11(b), as an example, the duty ratio at the target temperature Tt (shown in Figure 2) is 50%. The duty ratio at any temperature in the heat dissipation amount corresponding region is not particularly limited, but is preferably greater than 0% and less than 30%. In FIG. 11C, as an example, the duty ratio at any temperature in the heat radiation amount corresponding region is set to 20%.

[0057] In the heat amount control profiles shown in FIGS. 2 to 4 , the heat amount at the inflection point P is preferably 70% or less, and more preferably 60% or less, of the heat amount in the constant portion 120. If the heat amount at the inflection point P exceeds 70% of the heat amount in the constant portion 120, heating continues more than necessary even after the coolant temperature is raised and exceeds the target temperature Tt, making it difficult to control the coolant temperature T to approximate the target temperature Tt. The lower limit of the heat amount at the inflection point P is not particularly limited, but is preferably 30% or more, and more preferably 40% or more, of the heat amount in the constant portion 120. If the heat amount at the inflection point P is less than 30% of the heat amount in the constant portion 120, the heat amount may be insufficient when the coolant temperature approaches the target temperature Tt, and it may take a long time for the coolant temperature to reach the target temperature Tt.

[0058] As shown in FIG. 1, the vehicle air conditioning device 900 according to this embodiment is equipped with the heating cycle device 1 according to this embodiment and is mounted on a vehicle, the vehicle being capable of running using an electric motor, the vehicle air conditioning device 900 having a temperature control unit 901 that adjusts the temperature of the air supplied to the vehicle interior, and the radiator 7 being a hot water heat exchanger arranged inside the temperature control unit 901.

[0059] The vehicle air conditioning device 900 includes a blower unit 904 and a temperature adjustment unit 901. The blower unit 904 includes a blower 902 that blows air taken in through an inside air inlet and / or an outside air inlet (not shown) toward an air flow path 903. The internal space of the temperature adjustment unit 901 is the air flow path 903, and a hot water heat exchanger (radiator) 7 is disposed in the air flow path 903. It is preferable that the air conditioning device further includes a cooling heat exchanger (not shown) that dehumidifies and cools the air sent from the blower unit 904 as needed, and an air mix door (not shown) that is disposed between the cooling heat exchanger and the hot water heat exchanger 7 and adjusts the ratio of air passing through the hot water heat exchanger 7 and air bypassing the hot water heat exchanger 7, upstream of the air flow path 903 from the hot water heat exchanger 7. A defrost opening (not shown), a vent opening (not shown), and a foot opening (not shown) are provided at the most downstream portion of the temperature adjustment unit 901. Each opening is connected to an air outlet (not shown) in the vehicle cabin directly or indirectly via a duct (not shown).

[0060] Vehicles include, for example, electric vehicles (EVs) powered solely by an electric motor, hybrid electric vehicles (HEVs) powered by multiple power sources including an electric motor and an internal combustion engine, and vehicles powered by an electric motor driven by an internal combustion engine that generates electricity. These vehicles tend to have a smaller total coolant volume in the coolant loop than internal combustion vehicles. Therefore, if temperature hunting occurs at the outlet of the fluid heating unit, the hunting effect is likely to extend throughout the entire path. However, the heating cycle device 1 installed in the vehicle air conditioning system according to the present embodiment can minimize temperature hunting. When coolant temperature hunting occurs, if the vehicle air conditioning system 900 is operating in full-heat mode, the temperature of the warm air blown out from the air outlet in the vehicle cabin may fluctuate, potentially reducing comfort. Alternatively, if the vehicle air conditioning system 900 is operating in temperature-adjusting mode, the position of the air mix door must be frequently adjusted to maintain a constant temperature, potentially reducing comfort due to the operating noise of the air mix door actuator.

[0061] Although not shown, it is preferable to detect the air volume of the blower 902, the temperature of the air upstream of the radiator 7, and the temperature of the conditioned air downstream of the air mix door and input these values ​​to the heating control device 6 to estimate the amount of heat radiation in the radiator 7, and change the heating amount at the inflection point P in FIGS. 2 to 4 according to the amount of heat radiation in the radiator 7. Specifically, when the amount of heat radiation in the radiator 7 is relatively large, the inflection point P is adjusted to a value with a larger amount of heat radiation, and when the amount of heat radiation in the radiator 7 is relatively small, the inflection point P is adjusted to a value with a smaller amount of heat radiation. When the amount of heat radiation in the radiator 7 is large, the coolant temperature T can be made to reach the target temperature Tt quickly. When the amount of heat radiation in the radiator 7 is small, the coolant temperature T can be reliably prevented from further increasing after reaching the target temperature Tt, and the coolant temperature T can be controlled to approximate the target temperature Tt.

[0062] The present invention will be described in more detail below based on examples, but the present invention is not limited to these examples in any way.

[0063] Example 1 The heating control device controlled the switching operation of the transistor based on the heating amount control profile shown in Figure 2, and adjusted the amount of heat generated by the heater by changing the on-off duty ratio of the transistor. The target temperature was set to 80°C. Figure 12 is a diagram showing the relationship between heating time and coolant temperature in Example 1. In Figure 12, the region marked with reference numeral 301 corresponds to the constant portion 120 in Figure 2, the region marked with reference numeral 302 corresponds to the first decreasing portion 111, and the region marked with reference numeral 303 corresponds to the second decreasing portion 112.

[0064] (Comparative Example 1) The amount of heat generated by the heater was adjusted in the same manner as in Example 1, except that the heat amount control profile was changed to the profile shown in Fig. 7. The target temperature was set to 80°C. Fig. 13 is a diagram showing the relationship between heating time and coolant temperature in Comparative Example 1.

[0065] (Comparative Example 2) The amount of heat generated by the heater was adjusted in the same manner as in Example 1, except that the heat amount profile was changed to the profile shown in Fig. 9. The target temperature was set to 80°C. Fig. 14 is a diagram showing the relationship between heating time and coolant temperature in Comparative Example 2.

[0066] In Example 1, as shown in FIG. 12, the time to reach the target temperature was within 15 minutes, and the target temperature was reached in a short time. Furthermore, the temperature fluctuation from the target temperature was within ±1°C of the target temperature, and the temperature fluctuation was small. In contrast, in Comparative Example 1, as shown in FIG. 13, the time to reach the target temperature was within 15 minutes, but the temperature fluctuation from the target temperature was within ±5°C of the target temperature, and the temperature fluctuation was large. In Comparative Example 2, as shown in FIG. 14, the temperature fluctuation from the target temperature was within ±1°C of the target temperature, but the time to reach the target temperature exceeded 20 minutes, and the time to reach the target temperature was long.

[0067] DESCRIPTION OF SYMBOLS 1 Heating cycle device 2 Circulation flow path 3 Pump 4 Heater 5 Transistor 6 Heating control device 7 Radiator 8 Battery 10 Fluid heating unit 10a Outlet 10b Inlet 11, 12, 13 Pipe 50 Temperature sensor 100 (100A to 100E) Heating amount control profile 110 Decreasing section 111 First decreasing section 112 Second decreasing section 111A First region 111B Second region 111C Third region 112A Heat radiation amount corresponding region 200, 201, 202, 203 Profile 900 Vehicle air conditioning device 901 Temperature control unit 902 Blower 903 Air flow path 904 Blower unit P Inflection point

Claims

1. A heating control device (6) controls a transistor (5) that supplies power by switching operation to a heater (4) that generates heat when energized and heats a coolant that is supplied to a radiator (7) mounted in a vehicle air conditioner, The heating control device (6) controls the switching operation of the transistor (5) based on a heating amount control profile (100 (100A to 100E)) and adjusts the amount of heating by the heater (4) by changing the on-off duty ratio of the transistor (5); The heat amount control profile (100 (100A to 100E)) is a function showing the relationship between the temperature (T) of the coolant and the heat amount (E) by the heater (4), and has a decreasing section (110) in which the heat amount (E) decreases as the temperature (T) rises from the low temperature side to the high temperature side across a target temperature (Tt) of the coolant, The decrease section (110) has a first decrease section (111) when the temperature (T) is in a temperature range below the target temperature (Tt) and a second decrease section (112) when the temperature (T) is in a temperature range above the target temperature (Tt), and the first decrease section (111) and the second decrease section (112) have the same heating amount (E) at the target temperature (Tt); The first decrease portion (111) and the second decrease portion (112) both have a negative slope in the function, The first decrease portion (111) has a first region (111A) and a second region (111B) on the higher temperature side than the first region (111A), A heating control device characterized in that the slope of the heating amount control profile (100 (100A to 100E)) at any temperature in the second region (111B) is more negative than the slope of the heating amount control profile (100 (100A to 100E)) at any temperature in the first region (111A).

2. The decreasing portion (110) is a curve having an inflection point (P), 2. The heating control device according to claim 1, wherein the temperature (T) at which the inflection point (P) occurs coincides with the target temperature (Tt).

3. The decreasing portion (110) is a curve having an inflection point (P), The heating control device according to claim 1, wherein the temperature (T) at which the inflection point (P) occurs is higher than the target temperature (Tt).

4. The decreasing portion (110) is a curve having an inflection point (P), The temperature (T) at which the inflection point (P) occurs is lower than the target temperature (Tt), The heating control device according to claim 1 , wherein the second region (111B) is in a region on the lower temperature side than the inflection point (P).

5. The heating control device according to claim 1 , wherein the first region (111A) and the second region (111B) are linear functions having mutually different slopes in the function.

6. The heating control device according to claim 1, characterized in that the decreasing portion (110) is a curve that does not have an inflection point (P).

7. The heating control device according to claim 1, characterized in that the heating amount control profile (100 (100A to 100E)) has a constant portion (120) on the lower temperature side than the first decreasing portion (111), in which the heating amount (E) is constant even if the temperature (T) rises from the lower temperature side to the higher temperature side.

8. The heating control device according to claim 1, characterized in that the second reduction section (112) has a heat dissipation amount corresponding region (112A) on the higher temperature side than the target temperature (Tt) that maintains the heating amount (E) at a predetermined heating amount.

9. A heating control device according to any one of claims 1 to 8, comprising: a heater (4) that generates heat when energized to heat a coolant; a transistor (5) that supplies power to the heater (4) by switching operation; and The fluid heating unit (10) is characterized in that the heating control device (6) controls the switching operation of the transistor (5).

10. a circulation flow path (2), a coolant filled in the circulation flow path (2), a pump (3) that circulates the coolant through the circulation flow path (2), a fluid heating unit (10) according to claim 9 that adjusts the temperature of the coolant, and a radiator (7) that radiates heat from the coolant, The coolant is heated by energizing the heater (4) in the fluid heating unit (10) through the transistor (5).

11. A vehicle air conditioner (900) equipped with the heating cycle device (1) according to claim 10 and mounted on a vehicle, The vehicle is capable of running on an electric motor, The vehicle air conditioner (900) has a temperature adjustment unit (901) that adjusts the temperature of air supplied to a vehicle interior, The vehicle air conditioning system is characterized in that the radiator (7) is a hot water type heat exchanger disposed inside the temperature adjustment unit (901).

12. A control program for causing a heating control device (6) according to any one of claims 1 to 8 to execute a process for controlling the switching operation of the transistor (5) based on the heating amount control profile (100 (100A to 100E)).