Heating control device, control program product, fluid heating unit, heating cycle device, and vehicle air conditioning device

Abstract

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 having the heating cycle device, which can integrate a dry boil state detection function of a heat generating body and a low flow state detection function of a heat medium while suppressing an increase in the number of parts. The heating control device (6) of the present disclosure is mounted on a fluid heating unit (10) having a tank (15), a heater (4), a temperature detection device (51) having a temperature sensing portion in a downstream portion of a flow path, and a transistor (5), wherein the heating control device stores a value of a threshold speed Vt set based on a temperature rise speed V0 of the coolant in the downstream portion of the flow path when the liquid amount of the coolant is a prescribed amount and the flow rate of the coolant is 0 L / min, and calculates a temperature rise speed V based on a temperature detected by the temperature detection device, and when the value of the temperature rise speed is equal to or greater than the value of the threshold speed, the transistor is turned off to stop the application of power to the heater.

Description

TECHNICAL FIELD

[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-conditioning device provided with the heating cycle device. BACKGROUND

[0002] Conventionally, a vehicle air-conditioning device using a hot water type heating device that performs heating using hot water is known (for example, refer to Patent Literature 1). In the vehicle air-conditioning device of Patent Literature 1, a first switch and a second switch are provided, and by setting a target temperature of the hot water in the case where the second switch is activated to a value lower than a target temperature of the hot water in the case where the first switch is activated, a comfortable heating temperature can be obtained at the time of heating when the temperature in the vehicle cabin is high.

[0003] In addition, as a heater of the hot water type heating device, a fluid heating unit that heats a fluid using an electric heater is disclosed (for example, refer to Patent Literature 2).

[0004] As a heating device that prevents dry burning of a heater, a device that stops power supply to the heater when the electric resistance between the outer surfaces of different heaters is equal to or higher than an upper threshold value is known (for example, refer to Patent Literature 3).

[0005] PRIOR ART DOCUMENTS

[0006] PATENT LITERATURE

[0007] Patent Literature 1: Japanese Patent Application Publication No. H10-258630

[0008] Patent Literature 2: Japanese Patent Application Publication No. 2017-215084

[0009] Patent Literature 3: Japanese Patent Application Publication No. 2015-25594 SUMMARY

[0010] PROBLEMS TO BE SOLVED BY THE INVENTION

[0011] By using the power supply method to the electric heater of Patent Literature 1 in the fluid heating unit of Patent Literature 2, a liquid heat medium (for example, hot water) having a temperature close to the target temperature can be obtained. However, in order to obtain a heat medium having a temperature close to the target temperature by the technologies of Patent Literature 1 and Patent Literature 2, as a premise, it can be cited that the flow rate of the heat medium circulating in the heating device becomes a prescribed flow rate. In the case where the heat medium is supplied at the prescribed flow rate, if the prescribed power is supplied, the heat medium at the time of flowing out from the heating device becomes a prescribed temperature. However, in the case where the heat medium cannot be supplied at the prescribed flow rate due to a failure of a pump or the like for some reason, if the amount of power supplied is inappropriately reduced, a heat medium at the prescribed temperature cannot be obtained.

[0012] In addition, there is a case where the heat medium is not supplied to the tank of the heating device due to some cause such as a failure of the pump. At this time, if there is an error in the filling amount of the heat medium at the manufacturing stage that is less than a prescribed amount, or there is a failure due to some cause such as a leak of the piping that the liquid amount of the heat medium is less than a prescribed amount, the liquid level in the tank of the heating device drops, and the heating element becomes a dry heating state where it is exposed from the liquid level. If the heating element becomes a dry heating state, the surface temperature of the heating element becomes a temperature higher than that at the time of normal operation, and it is possible that the components of the heat medium are unexpectedly precipitated, or the heating element is broken.

[0013] Thus, in the heating device, it is required to detect both the low flow state and the dry heating state. The heating device of Patent Literature 3 is able to detect the dry heating state by the resistance values between the outer surfaces of the different heaters, but is not able to detect the low flow state. In order to detect the low flow, it is necessary to add other functions, and the number of parts increases. In addition, the heating device of Patent Literature 3 needs to be arranged with a plurality of heating elements, and there is a problem that the heating device is large-sized. In a case where the vehicle front room (a space formed in front of an interior space in which an occupant rides, which is partitioned from the interior space) in which the heating device is arranged is arranged with a plurality of devices, it is desired to save the space of the heating device.

[0014] An object of the present disclosure is to provide a heating control device and control program, a fluid heating unit, a heating cycle device, and a vehicle air conditioning device provided with the heating cycle device, which are able to integrate the detection function of the dry heating state of the heating element and the detection function of the low flow state of the heat medium, and suppress an increase in the number of parts.

[0015] Technical solution for solving the technical problem

[0016] The heating control device of the present disclosure is mounted on a fluid heating unit that is provided with: a tank that has an inlet, a flow path, and an outlet of a coolant, and connects the inlet and the outlet to a circulation flow path; a heater that is arranged in the flow path, generates heat by being energized, and thereby heats the coolant; a temperature detection device that has a temperature sensing portion in a downstream portion of the flow path; and a transistor that supplies electric power to the heater, characterized in that the heating control device stores a value of a threshold speed that is set based on a temperature rising speed of the coolant in the downstream portion of the flow path when the liquid amount of the coolant is a prescribed amount and the flow rate of the coolant is 0 L / min, and calculates a temperature rising speed based on a temperature detected by the temperature detection device, and when the value of the temperature rising speed is equal to or higher than the value of the threshold speed, the transistor is turned off to stop the application of electric power to the heater.

[0017] Preferably, the heating control device of the present application calculates a temperature increase value within a prescribed time after the application of power to the heater is stopped, based on the temperature detected by the temperature detecting device, and determines that the heater is in a dry heating state due to a decrease in the liquid amount of the coolant in the tank when the temperature increase value is equal to or greater than a prescribed increase value, and determines that the zero flow state is present but the liquid amount of the coolant is within a prescribed amount when the temperature increase value is less than the prescribed increase value. The cause of the abnormality can be appropriately grasped. As a result, the treatment to be performed thereafter can be appropriately determined.

[0018] Preferably, the heating control device of the present application stores a liquid amount temperature increase map indicating the relationship between the temperature increase value and the liquid amount of the coolant in the tank, and derives the estimated liquid amount of the coolant in the tank corresponding to the calculated temperature increase value based on the liquid amount temperature increase map when it is determined that the heater is in a dry heating state. The degree of the abnormality can be appropriately grasped. As a result, the treatment to be performed thereafter can be appropriately determined.

[0019] Preferably, the heating control device of the present application is provided with a flow rate temperature increase map indicating the relationship between the temperature increase rate of the coolant in the downstream portion of the flow path when the heating amount of the heater is a prescribed heating amount and the flow rate of the coolant, and the value of the threshold speed is set based on the flow rate temperature increase map. The map for grasping the flow rate can be used as is.

[0020] Preferably, in the heating control device of the present application, the temperature sensing portion is disposed at a position higher than the heater. The decrease in the liquid level in the tank can be detected more quickly.

[0021] The fluid heating unit of the present application is characterized by comprising: a tank having a flow inlet, a flow path, and a flow outlet of a coolant, and connecting the flow inlet and the flow outlet to a circulation flow path; a heater disposed in the flow path, which generates heat by being energized to thereby heat the coolant; a temperature detecting device having a temperature sensing portion in a downstream portion of the flow path; a transistor that supplies power to the heater; and the heating control device of the present application, which controls the transistor to supply power to the heater.

[0022] The heating cycle device of the present application is characterized by comprising: a circulation flow path; a coolant filled in the circulation flow path; a pump that circulates the coolant in the circulation flow path; the fluid heating unit of the present application that temperature-regulates the coolant; a radiator that radiates heat from the coolant heated by the heater in the fluid heating unit by being energized by the transistor.

[0023] The vehicle air-conditioning device of the present application is provided with the heating cycle device of the present application, and is mounted on a vehicle, and is characterized in that the vehicle is capable of traveling by means of an electric motor, and the vehicle air-conditioning device has a temperature adjustment unit that adjusts the temperature of air supplied to the vehicle cabin, and the radiator is a hot water type heat exchanger that is arranged inside the temperature adjustment unit.

[0024] The control program of the present application is characterized in that it causes the heating control device of the present application to execute a process that controls the supply of electric power from the transistor to the heater based on the temperature increase rate.

[0025] Effects of the Invention

[0026] 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 provided with the heating cycle device, which can integrate the detection function of the dry-running state of the heat generating body and the detection function of the low flow rate state of the heat medium to suppress an increase in the number of parts. BRIEF DESCRIPTION OF DRAWINGS

[0027] Figure 1 is a block diagram showing one example of the fluid heating unit, the heating cycle device, and the vehicle air-conditioning device provided with the heating cycle device of the present embodiment.

[0028] Figure 2 is a schematic cross-sectional view showing one example of a tank of the fluid heating unit.

[0029] Figure 3 is a graph for explaining the temperature increase rate of the coolant.

[0030] Figure 4 is a graph in which the flow rate temperature map is curved, (a) shows a first example, and (b) shows a second example.

[0031] Figure 5 is a graph showing the temporal change in the detection temperature in the dry-running state. DETAILED DESCRIPTION

[0032] Hereinafter, one mode of the present application will be described with reference to the drawings. The embodiments described below are examples of the present application, and the present application is not limited to the following embodiments. Note that, in the present specification and the drawings, the same reference numerals are used to denote the same elements. Various modifications can be made as long as the effects of the present application are achieved. In the description, up and down refer to up and down with respect to a vehicle on which a vehicle fluid heating unit is mounted.

[0033] Figure 1is a block diagram showing one example of a fluid heating unit, a heating cycle device, and a vehicle air-conditioning device provided with the heating cycle device according to the present embodiment. The heating control device 6 according to the present embodiment is mounted on a fluid heating unit 10 provided with a tank 15 having a flow inlet 10b, a flow path 10c, and a flow outlet 10a of a coolant, and the flow inlet 10b and the flow outlet 10a are connected to the circulating flow path 2; a heater 4 disposed in the flow path 10c, which generates heat by electric conduction to thereby heat the coolant; a temperature detecting device 51 having a temperature sensing portion 51a at a downstream portion of the flow path 10c; and a transistor 5 that supplies electric power to the heater 4. The heating control device 6 stores a value of a threshold speed Vt set based on a temperature increase speed V0 of the coolant at the downstream portion of the flow path 10c when the liquid amount of the coolant is a prescribed amount and the flow rate of the coolant is 0 L / min (liters per minute), and calculates a temperature increase speed V based on a temperature detected by the temperature detecting device 51, and when the value of the temperature increase speed V is equal to or higher than the value of the threshold speed Vt, causes the transistor 5 to be turned off to stop the application of electric power to the heater 4.

[0034] The fluid heating unit 10 according to the present embodiment is provided with a tank 15 having a flow inlet 10b, a flow path 10c, and a flow outlet 10a of a coolant, and the flow inlet 10b and the flow outlet 10a are connected to the circulating flow path 2; a heater 4 disposed in the flow path 10c, which generates heat by electric conduction to thereby heat the coolant; a temperature detecting device 51 having a temperature sensing portion 51a at a downstream portion of the flow path 10c; a transistor 5 that supplies electric power to the heater 4; and a heating control device 6 according to the present embodiment that controls the supply of electric power to the heater 4 by the transistor 5.

[0035] In the fluid heating unit 10, the heater 4 is caused to generate heat by the supply of electric power to the heater 4 by the transistor 5, to thereby heat the coolant supplied to the radiator 7 of the vehicle air-conditioning device. At this time, the heating control device 6 controls the on-off operation of the transistor 5, changes the duty ratio of the on-off of the transistor 5 to adjust the amount of heat from the heater 4, to thereby adjust the temperature of the coolant.

[0036] Figure 2 is a schematic cross-sectional view showing one example of a tank of a fluid heating unit. The tank 15 is a part of a housing 14 that constitutes an outer shell of the fluid heating unit 10. The housing 14 is constituted by, for example, a metal such as an aluminum alloy, or a heat-resistant resin such as 6,6-nylon, and as shown in Figure 2As shown, it may also have a cover 14a, a lid 14b, and a housing body 14c. The housing body 14c is a cylindrical member with an opening at one end. The lid 14b is a plate-like member that closes the opening of the housing body 14c. In this configuration, the can 15 is formed by closing the opening of the housing body 14c with the lid 14b. The cover 14a is a lid-like member that covers the upper wall of the housing body 14c. The space enclosed by the cover 14a and the upper wall of the housing body 14c forms a storage chamber 18. Electrical components such as the transistor 5, a heating control device 6, and a substrate 19 are stored in the storage chamber 18.

[0037] like Figure 2 As shown, tank 15 has a coolant flow path 10c as its internal space, allowing coolant flowing in from inlet 10b to flow outlet 10a. Heater 4 is housed within tank 15. Inlet connecting pipe 16 is connected to inlet 10b. Inlet connecting pipe 16 is connected to pipe 13, which forms the circulation flow path 2 (in... Figure 1 (See diagram in the middle) connection. Alternatively, pipe 13 can also serve as an inlet connection pipe 16. An outlet connection pipe 17 is connected to the outlet 10a. The outlet connection pipe 17 connects to pipe 11, which forms the circulation path 2 (in... Figure 1 (See diagram in the middle) Connection. Alternatively, pipe 11 can also serve as an outlet connection to pipe 17.

[0038] Heater 4 is an electric heating element that generates heat by passing electricity through it. There is no particular limitation on its type. For example, a fuse heater can be obtained by wrapping a nickel-chromium alloy wire in a metal tube.

[0039] Temperature detection device 51 is, for example, a temperature sensor. Figure 2 As shown, the temperature sensing part 51a of the temperature detection device 51 is located in the downstream portion of the flow path 10c. The downstream portion of the flow path 10c is, for example, near the outlet 10a. Even if there is a temperature deviation in the coolant due to the position of the tank 15, the coolant collects at the outlet 10a when flowing out of the tank 15, thereby mixing the coolant and enabling accurate temperature detection. Furthermore, as... Figure 2 As shown, the temperature sensing part 51a of the temperature detection device 51 is more preferably located in the flow path 10c near the outlet 10a. By positioning the temperature sensing part 51a upstream of the outlet 10a, the temperature can be detected before unwanted heat dissipation of the coolant occurs, enabling high-precision detection of the thermal energy moving from the heater 4 to the coolant. Figure 2 As shown, the temperature sensing unit 51a is preferably positioned above the heater 4. This allows for more rapid detection of a drop in the liquid level within the tank 15.

[0040] Transistor 5 is preferably, for example, an insulated gate bipolar transistor (IGBT). Figure 1 As shown, transistor 5 is electrically connected to battery 8. Additionally, transistor 5 is electrically connected to heating control device 6 and switches on and off according to command signals from heating control device 6. Transistor 5 controls the power supply to heater 4 through its switching action. By changing the on-off duty cycle of transistor 5, the heating output from heater 4 can be adjusted, thus adjusting the heat supplied to the coolant. Figure 1 As shown, the fluid heating unit 10 is configured with at least a heater 4, a transistor 5, a heating control device 6, and electrical wiring 55 that connects them to form a circuit with the battery 8.

[0041] like Figure 1 As shown, the heating circulation device 1 of this embodiment includes a circulation path 2, a coolant filled in the circulation path 2, a pump 3 for circulating the coolant in the circulation path 2, a fluid heating unit 10 of this embodiment for adjusting the temperature of the coolant, and a radiator 7 for dissipating heat from the coolant. The coolant is heated in the fluid heating unit 10 by a heater 4 being energized by a transistor 5.

[0042] The heating circulation device 1 is a device that generates heat by exchanging heat between the coolant and the air passing through the radiator 7 in the vehicle air conditioning system. The coolant is obtained by adjusting the temperature of the warm air for heating using the fluid heating unit 10.

[0043] The circulation path 2 includes: a pipe 11 that connects the outlet 10a of the tank 15 that houses the heater 4 to the inlet of the coolant in the radiator 7; a pipe 12 that connects the outlet of the coolant in the radiator 7 to the pump 3; and a pipe 13 that connects the pump 3 to the inlet 10b of the tank 15.

[0044] The coolant (not shown) is a liquid at room temperature, such as a heat medium obtained by dissolving ethylene glycol or glycerol in water.

[0045] Radiator 7 is a hot water heat exchanger. Radiator 7 has internal coolant flow paths.

[0046] like Figure 1As shown, the tank 15, the circulation flow path 2, the flow path in the radiator 7, and the flow path in the pump 3 constitute a coolant circuit 9. In the coolant circuit 9, the coolant is delivered by the pump 3, introduced into the tank 15 from the flow inlet 10b through the pipe 13, and heated by the heater 4 built in the tank 15. Next, the heated coolant is discharged from the flow outlet 10a of the tank 15, sent to the radiator 7 through the pipe 11, and radiated to heat the air-conditioning air. The coolant that has passed through the radiator 7 is sucked into the pump 3 through the pipe 12 to circulate. The coolant circuit 9 is filled with a prescribed amount of coolant in a prescribed state. At this time, as shown, the liquid level Ln of the coolant in the tank 15 (hereinafter, the liquid level in the prescribed state is also referred to as the prescribed liquid level Ln) is located at a position higher than the heater 4. Figure 2

[0047] In the operation of the fluid heating unit 10, the flow rate of the coolant circulating in the coolant circuit 9 is set to a prescribed flow rate (set flow rate) such as 10 L / min, for example. Here, the flow rate of the coolant is the volume of the coolant flowing in the circulation flow path 2 per unit time in the heating cycle device 1. However, due to some cause such as a failure of the pump 3 or a pipe leakage, there is a possibility that the coolant cannot be supplied at the set flow rate. In the operation of the fluid heating unit 10, if the flow rate of the coolant is less than the set flow rate, there is a possibility that abnormal heat generation due to boiling of the coolant occurs locally, which can affect the reliability of the fluid heating unit 10.

[0048] In addition, there is a possibility that the liquid amount of the coolant is less than the prescribed amount due to some cause such as an error in which the filling amount of the coolant is less than the prescribed amount at the manufacturing stage or a pipe leakage. Even in this case, as long as the coolant circulates in the coolant circuit 9 by driving of the pump 3, at least the tank 15 is filled with the coolant. Therefore, the liquid level of the coolant in the tank 15 is located at a position higher than the heater 4 as with the prescribed liquid level Ln as shown. However, if the coolant does not circulate in the coolant circuit 9 due to some cause such as a failure of the pump 3, there is a possibility that the liquid level La of the coolant in the tank 15 (illustrated in FIG. 2) is lower than the prescribed liquid level Ln and located at a position lower than the upper end of the heater 4 (hereinafter, the liquid level in the lowered state is also referred to as the lowered liquid level La). Figure 2 Figure 2 If the heater 4 is in the dry heating state, the surface temperature of the heater 4 becomes a temperature higher than the temperature at the time of normal operation, and there is a concern that components of the coolant are unexpectedly separated and the heater 4 is damaged.

[0049] ​​As described above, in the fluid heating unit 10, it is required to detect an abnormality in the flow rate of the coolant and a dry-running state. In the past, separate detection functions have been employed for the two failure modes. However, there is a problem of an increase in the number of parts. Therefore, the heating control device 6 of the present embodiment performs both the detection of the flow rate of the coolant and the detection of the dry-running state using the temperature of the downstream portion of the flow path 10c in the fluid heating unit 10. By sharing the detection functions of the two failure modes, it is possible to suppress an increase in the number of parts.

[0050] Next, a method in which the heating control device 6 performs both the detection of the flow rate of the coolant and the detection of the dry-running state using the temperature of the downstream portion of the flow path 10c in the fluid heating unit 10 will be described.

[0051] First, the heating control device 6 calculates the temperature rise rate V based on the temperature detected by the temperature detection device 51. The calculation of the temperature rise rate V is performed, for example, as follows. After the energization to the heater 4 is started, the temperature detected by the temperature detection device 51 at a certain time t is set to X, and the temperature detected by the temperature detection device 51 at a time (t - Δt) that is a predetermined time Δt before the time t is set to X', then the temperature rise rate V at the time t can be calculated as {(X - X') / Δt}. The predetermined time Δt is not particularly limited, and is, for example, 1 to 5 seconds. The heating control device 6, for example, acquires the temperature detected by the temperature detection device 51 every 10 ms, and calculates the temperature rise rate V every 1 second.

[0052] Next, the heating control device 6 sends an instruction signal to turn off the switching operation of the transistor 5 when the calculated temperature increase rate V is equal to or greater than the threshold value Vt. Preferably, the heating control device 6 calculates the temperature increase rate V at regular intervals (for example, 1 second), and turns off the transistor 5 when the calculated temperature increase rate V is equal to or greater than the threshold value Vt for a predetermined number of consecutive times (for example, 8 times). The threshold value Vt is preferably equal to or less than the temperature increase rate V0 (hereinafter, sometimes referred to as the zero-flow temperature increase rate V0) of the coolant in the downstream portion of the flow path 10c when the liquid amount of the coolant is a predetermined amount and the flow rate of the coolant is 0 L / min. In other words, the threshold value Vt is preferably equal to or less than the zero-flow temperature increase rate V0. The lower limit of the threshold value Vt is not particularly limited, and is preferably equal to or greater than the zero-flow temperature increase rate V0 - 0.5°C / min, for example. The case where the temperature increase rate V is equal to or greater than the threshold value Vt indirectly indicates a zero-flow state in which the coolant is not supplied to the tank 15 due to some reason, that is, the flow rate of the coolant is 0 L / min. In the zero-flow state, there are a case where the liquid amount of the coolant contained in the tank 15 decreases and the heater 4 is in a dry heating state, and a case where the flow rate is zero but the liquid amount of the coolant is within a predetermined range. In either case, if the heating of the coolant by the heater 4 continues, a secondary damage can occur, and therefore the application of power to the heater 4 is stopped.

[0053] In the heating control device 6, as the threshold value Vt, a value set in advance is stored, or a flow rate-temperature increase map indicating the relationship between the temperature increase rate of the coolant in the downstream portion of the flow path 10c and the flow rate of the coolant when the amount of heating of the heater 4 is a predetermined heating amount E 100 may be set based on the flow rate-temperature increase map. The latter can use the map for grasping the flow rate. The predetermined heating amount E 100 is not particularly limited, and is 7 kW / h, for example.

[0054] Next, in describing the flow rate-temperature increase map, reference will be made to Figure 3 the temperature increase rate of the coolant. Figure 3 is a graph for explaining the temperature increase rate of the coolant. Figure 3is a graph showing the relationship between elapsed time and the temperature of the coolant at the downstream portion of the flow path 10c when the liquid amount of the coolant is a prescribed amount and the heating amount of the heater 4 is 7 kW / h, and is a graph 801 when the flow rate is 0 L / min (0 L / h), a graph 802 when the flow rate is 2 L / min (120 L / h), a graph 803 when the flow rate is 5 L / min (300 L / h), and a graph 804 when the flow rate is 10 L / min (600 L / h), respectively. The horizontal axis is elapsed time, and the unit is minute. The vertical axis is the temperature of the coolant at the downstream portion of the flow path 10c, and the unit is °C. The temperature of the coolant at the downstream portion of the flow path 10c is detected by the temperature detecting device 51, for example. These graphs 801, 802, 803, 804 have rising portions 801a, 802a, 803a, 804a at the initial stage of heating of the heater 4. The initial stage of heating of the heater 4 is preferably within 60 seconds from when the heater 4 is powered on, and more preferably within 20 to 30 seconds from when the heater 4 is powered on. The temperature rising speed of the coolant is the slope of the tangent line of the rising portion 801a, 802a, 803a, 804a. Among them, the slope of the tangent line of the rising portion 801a is the temperature rising speed V0 at zero flow rate. The unit of the temperature rising speed of the coolant is °C / min. As shown in Figure 3 (a), if the flow rate of the coolant is different when the heating amount of the heater 4 is a prescribed amount, the temperature rising speed of the coolant is different. In more detail, there is a tendency that the less the flow rate of the coolant, the faster the temperature rising speed of the coolant. The flow rate-temperature rising map functions this tendency.

[0055] Figure 4 is a graph in which the flow rate-temperature rising map is curved, Figure 4 (a) shows a first example, Figure 4 (b) shows a second example. The flow rate-temperature rising map is stored in a storage portion (not shown) of the heating control device 6. The flow rate-temperature rising map 850 (851, 852) is a function showing the relationship between the temperature rising speed of the coolant at the downstream portion of the flow path 10c and the flow rate of the coolant when the heating amount of the heater 4 is a prescribed amount, and is shown as a graph in which the horizontal axis is the temperature rising speed of the coolant at the downstream portion of the flow path 10c and the vertical axis is the flow rate of the coolant, for example, as shown in Figure 4 (a) and Figure 4 (b). The flow rate-temperature rising map 850 (851, 852) is a function in which the slope is negative, for example, a first function 851 as shown in Figure 4 (a) or Figure 4(b) a graph showing a function 852 of inverse proportionality. The heating control device 6 of the embodiment can acquire the zero-flow temperature increase rate V0 from the flow-temperature map 850 (851, 852) and set the threshold rate Vt. In addition, the zero-flow temperature increase rate V0 is the temperature increase rate at zero flow in a state where the coolant circuit 9 is filled with a prescribed amount of coolant, but instead of the zero-flow temperature increase rate V0, the threshold rate Vt can be set tentatively using the temperature increase rate V0' of the coolant detected by the temperature detecting device 51 in a state where the tank 15 is filled with a full amount of coolant and the fluid heating unit 10 is made into a closed system by occluding the flow inlet 10b and the flow outlet 10a of the tank 15. The temperature increase rate V0' is substantially the same as the zero-flow temperature increase rate V0.

[0056] In the case of the zero-flow state and the heater 4 being in the dry-running state, the temperature detected by the temperature detecting device 51 is the temperature of the air heated by the heater 4. On the other hand, in the case of the zero-flow state and the liquid amount of the coolant being in the prescribed range, the temperature detected by the temperature detecting device 51 is the temperature of the coolant heated by the heater 4. Since the specific heat of the coolant is higher than the specific heat of the air, in the case of imparting the same amount of heat to the same volume, the temperature of the air is higher than the temperature of the coolant. The heating control device 6 of the embodiment utilizes this phenomenon to determine, after the transistor 5 is turned off, which of the case where the liquid amount of the coolant in the tank 15 is reduced and the heater 4 is in the dry-running state or the case where the liquid amount of the coolant is in the prescribed range. Specifically, it is preferable that the heating control device 6 of the embodiment calculate the temperature increase ΔT in a prescribed time after the application of power to the heater 4 is stopped based on the temperature detected by the temperature detecting device 51, and determine that the liquid amount of the coolant in the tank 15 is reduced and the heater 4 is in the dry-running state when the temperature increase ΔT is a prescribed increase Tp or more, and determine that the zero-flow state is present but the liquid amount of the coolant is in the prescribed range when the temperature increase ΔT is less than the prescribed increase Tp. As a result, the cause of the generated abnormality can be grasped appropriately. As a result, the treatment to be performed thereafter can be determined appropriately. The treatment to be performed thereafter is, for example, replenishing the coolant, replacing or repairing the fluid heating unit 10 in the case of the dry-running state. In addition, replacing or repairing the pump 3 in the case where the liquid amount of the coolant is in the prescribed range. The prescribed time after the application of power to the heater 4 is stopped is not particularly limited and is, for example, 30 to 120 seconds. The prescribed increase Tp differs depending on the capacity of the tank 15 and the composition of the coolant and the like, and is, for example, 5 to 8°C.

[0057] Preferably, the heating control device 6 of this embodiment stores a liquid amount temperature rise map indicating a relationship between the temperature rise value ΔT and the liquid amount of the coolant in the tank 15, and derives the estimated liquid amount of the coolant in the tank 15 corresponding to the calculated temperature rise value ΔT on the basis of the liquid amount temperature rise map when it is determined that the heater 4 is in the dry-burning state.

[0058] Figure 5 is a graph indicating the temporal change of the detection temperature in the dry-burning state. In Figure 5 , the horizontal axis is the elapsed time [sec] and the vertical axis is the detection temperature [°C] of the temperature detection device 51. Both of the graphs 701, 702 are graphs in the case where the liquid level in the tank 15 is the falling liquid level La (illustrated in Figure 2 ). The graph 701 is a graph in the case where the liquid amount in the tank 15 is relatively small, and the graph 702 is a graph in the case where the liquid amount in the tank 15 is relatively large. In Figure 5 , the difference ΔT (ΔT1, ΔT2) between the detection temperatures at the time t1, t2 when the detection temperature rises from the start of the energization to the heater 4 at t0 and the energization to the heater 4 is stopped at the threshold speed Vt or more, and the detection temperatures at the time t 1+α , t 2+α after the elapse of a predetermined time α after t1, t2 is illustrated. In the case where the liquid amount is relatively small, in other words, in the case where the air amount is relatively large. On the contrary, in the case where the liquid amount is relatively large, in other words, in the case where the air amount is relatively small. Since the specific heat of the coolant is higher than that of the air, as illustrated in Figure 5 , the temperature rise value ΔT1 of the graph 701 in the case where the liquid amount is relatively small (the air amount is relatively large) is larger than the temperature rise value ΔT2 of the graph 702 in the case where the liquid amount is relatively large (the air amount is relatively small). In this way, there is a tendency that the temperature rise value ΔT is larger as the liquid amount is smaller (the air amount is larger). The liquid amount temperature rise map functions the tendency. When the liquid amount temperature rise map is displayed as a graph in which the horizontal axis is ΔT and the vertical axis is the liquid amount of the coolant in the tank 15, the liquid amount temperature rise map is represented by a graph of a function having a negative slope, or a function of inverse proportion, or the like, for example. The estimated liquid amount of the coolant in the tank 15 is derived on the basis of the liquid amount temperature rise map, and thus the degree of the abnormality can be appropriately grasped. As a result, the treatment to be performed thereafter can be appropriately determined. The treatment to be performed thereafter is, for example, the replenishment of the coolant in the case where the estimated liquid amount is relatively large. In addition, in the case where the estimated liquid amount is relatively small, the possibility that the heater 4 is broken is high, and thus the fluid heating unit 10 is replaced or repaired.

[0059] As Figure 1As shown, the vehicle air-conditioner 900 of the present embodiment is a vehicle air-conditioner in which the heating cycle device 1 of the present embodiment is mounted on a vehicle capable of traveling by an electric motor, and has a temperature adjustment unit 901 that adjusts the temperature of air supplied to the vehicle cabin. The radiator 7 is a hot-water type heat exchanger disposed inside the temperature adjustment unit 901.

[0060] The vehicle air-conditioner 900 has a blower unit 904 and the temperature adjustment unit 901. The blower unit 904 is provided with a blower 902 that blows air taken in from an internal air inlet and / or an external air inlet, not shown, toward the air flow path 903. The inside of the temperature adjustment unit 901 is the air flow path 903, and the hot-water type heat exchanger (radiator) 7 is disposed in the air flow path 903. Preferably, on the upstream side of the air flow path 903 with respect to the hot-water type heat exchanger 7, there are further provided a cooling heat exchanger, not shown, that dehumidifies and cools air supplied from the blower unit 904 as necessary, and an air mixing damper, not shown, disposed between the cooling heat exchanger and the hot-water type heat exchanger 7, that modulates the proportion of air that passes through the hot-water type heat exchanger 7 to air that bypasses the hot-water type heat exchanger 7. A defrosting opening portion, not shown, a ventilation opening portion, not shown, and a foot opening portion, not shown, are provided at the most downstream portion of the temperature adjustment unit 901. Each of the opening portions is connected to an outlet, not shown, in the vehicle cabin indirectly or directly via a duct, not shown.

[0061] The vehicle includes, for example, an electric vehicle (EV) that travels by an electric motor alone, a hybrid vehicle (HEV) that travels by a plurality of power sources including an electric motor and an internal combustion engine, or a vehicle in which an internal combustion engine generates electric power and the vehicle travels by an electric motor that is driven using the electric power. In these vehicles, there is a tendency for the total coolant amount of the coolant circuit to be less than that of an engine-mounted vehicle, and when the liquid amount of the coolant decreases due to some malfunction, the surface temperature of the heater 4 easily becomes an abnormally high temperature as the heater 4 is exposed from the coolant, and in this case, the heating cycle device 1 mounted on the vehicle air-conditioner of the present embodiment can early detect a decrease in the liquid amount.

[0062] The control program of the present embodiment causes the heating control device 6 of the present embodiment to perform processing that controls the electric power supply from the transistor 5 to the heater 4 based on the temperature increase rate V. The execution of the control program includes, for example, the following process. First, the temperature detected by the temperature detection device 51 is detected, and the temperature increase rate V is calculated. Then, the calculated temperature increase rate V is compared with the threshold rate Vt. When the temperature increase rate V is equal to or greater than the threshold rate Vt, control is performed to turn off the transistor 5.

[0063] Explanation of Reference Numerals

[0064] 1: heating cycle device; 2: cycle flow path; 3: pump; 4: heater; 5: transistor; 6: heating control device; 7: radiator; 8: battery; 9: coolant circuit; 10: fluid heating unit; 10a: flow outlet; 10b: flow inlet; 10c: flow path; 11, 12, 13: pipe; 14: housing; 15: tank; 16: flow inlet connection pipe; 17: flow outlet connection pipe; 51: temperature detecting device; 51a: temperature sensing portion; 55: electric wiring; 801, 802, 803, 804: graphs; 801a, 802a, 803a, 804a: rising portions; 850 (851, 852): flow rate temperature rise map; 900: vehicle air conditioning device; 901: temperature adjusting unit; 902: air blower; 903: air flow path; 904: blower unit; Ln: prescribed liquid level; La: lowered liquid level.

Claims

1. A heating control device (6) mounted on a fluid heating unit (10) having a tank (15) having a coolant inlet (10b), a flow path (10c), and a coolant outlet (10a), and connecting the coolant inlet (10b) and the coolant outlet (10a) to a circulation flow path (2), a heater (4) disposed in the flow path (10c) and generating heat by energization to heat the coolant, and a temperature detecting device (51) having a temperature sensing portion at a downstream portion of the flow path (10c), and a transistor (5) supplying electric power to the heater (4), characterized in that the heating control device (6) stores a threshold speed Vt value set based on a temperature rise speed V0 of the coolant at the downstream portion of the flow path (10c) when the coolant amount is a prescribed amount and the coolant flow rate is 0 L / min, and calculates a temperature rise speed V based on a temperature detected by the temperature detecting device (51), and turns off the transistor (5) to stop the supply of electric power to the heater (4) when the temperature rise speed V value is equal to or greater than the threshold speed Vt value. wherein the heating control device (6) calculates a temperature rise value ΔT within a prescribed time after the supply of electric power to the heater (4) is stopped based on the temperature detected by the temperature detecting device (51), determines that the heater (4) is in a dry heating state due to a decrease in the coolant amount in the tank when the temperature rise value ΔT is equal to or greater than a prescribed rise value Tp, determines that a zero flow state is present but the coolant amount is within a prescribed range when the temperature rise value ΔT is less than the prescribed rise value Tp, and wherein the heating control device (6) stores a coolant amount temperature rise map representing a relationship between the temperature rise value ΔT and the coolant amount in the tank (15), and derives a presumed coolant amount in the tank (15) corresponding to the calculated temperature rise value ΔT based on the coolant amount temperature rise map when it is determined that the heater (4) is in a dry heating state.

2. The heating control device according to claim 1, characterized in that The heating control device (6) stores a value indicating that the heating amount of the heater (4) is a predetermined heating amount E. 100 The flow rate temperature rise mapping is a relationship between the rate of temperature rise of the coolant downstream of the flow path (10c) and the flow rate of the coolant. The value of the threshold rate is set based on the flow rate temperature rise mapping. the temperature sensing portion is disposed at a position higher than the heater (4). a tank (15) having a coolant inlet (10b), a flow path (10c), and a coolant outlet (10a), and connecting the coolant inlet (10b) and the coolant outlet (10a) to a circulation flow path (2), a heater (4) disposed in the flow path (10c) and generating heat by energization to heat the coolant, a temperature detecting device (51) having a temperature sensing portion at a downstream portion of the flow path (10c), a transistor (5) supplying electric power to the heater (4), and the heating control device (6) according to claim 1 or 2, 3. A fluid heating unit, characterized by, the heating control device (6) controls the transistor (5) to supply electric power to the heater (4). ​ 4. A heating cycle apparatus characterized by comprising: provided with: a circulation flow path (2); a coolant filled in the circulation flow path (2); a pump (3) circulating the coolant in the circulation flow path (2); the fluid heating unit (10) according to claim 3, which warms the coolant; a radiator (7) radiating the coolant, the coolant is heated in the fluid heating unit (10) by the heater (4) energized by the transistor (5).

5. A vehicle air conditioning device (900) provided with the heating cycle device (1) according to claim 4, mounted on a vehicle, characterized in that, the vehicle is capable of traveling by an electric motor, the vehicle air conditioning device (900) has a temperature adjustment unit (901) adjusting the temperature of air supplied to the vehicle cabin, the radiator (7) is a hot water type heat exchanger arranged inside the temperature adjustment unit (901).

6. A control program product characterized by The heating control device (6) according to claim 1 or 2 is caused to perform a process of controlling the supply of electric power from the transistor (5) to the heater (4) based on the temperature increase rate V.

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