Control device for ceramic heater module, ceramic heater unit and computer program product

Abstract

The invention provides a control device of a ceramic heater module, a ceramic heater unit and a computer program product. A control device controls a ceramic heater module provided with: a ceramic heater having a ceramic base body in which a resistance heating element is embedded; and a housing that accommodates the ceramic heater and has an inlet and an outlet through which the liquid medium flows. The control device is provided with: a means for acquiring an outlet temperature, which is the temperature of the outlet side of the ceramic heater module; and a means for determining whether or not a predetermined stop condition is satisfied on the basis of a temperature difference between a start temperature, which is an outlet temperature acquired at a power-on start time at which the resistance heating element is started to be powered on by the predetermined power, and a detected temperature, which is an outlet temperature acquired at a power-on start time at which the resistance heating element is started to be powered on by the predetermined power. The detected temperature is the outlet temperature obtained at one or more specific time points after the electrifying starting time point; and a means for stopping the supply of electricity to the resistive heating element when it is determined that the stop condition is satisfied.

Description

Technical Field

[0001] This disclosure relates to a control device for a ceramic heater module, a ceramic heater unit, and a control program for the ceramic heater module. Background Technology

[0002] Traditionally, PTC heaters and sheath heaters have been known as heaters for controlling the heating of a heat medium. For example, in Patent Document 1, a PTC heater is illustrated as a heating device for heating a battery mounted in a battery-powered vehicle.

[0003] Existing technical documents

[0004] Patent documents

[0005] Patent Document 1: Japanese Patent Application Publication No. 2023-136087 Summary of the Invention

[0006] The problem the invention aims to solve

[0007] These heaters suffer from drawbacks such as slow heating, large size, and heavy weight. Therefore, the use of ceramic heater modules is being researched. A ceramic heater module comprises a ceramic heater and a housing. The ceramic heater has a ceramic substrate with an embedded resistance heating element, which heats the liquid flowing on its surface. The housing houses the ceramic heater and has an inlet and an outlet for liquid flow. When heating the liquid with the ceramic heater, the ceramic heater is heated by the resistance heating element and cooled by the liquid. Therefore, the surface temperature of the ceramic heater gradually approaches a predetermined temperature that achieves equilibrium between heating by the resistance heating element and cooling by the liquid. Furthermore, the liquid flowing on the surface of the ceramic heater, which is gradually approaching the predetermined temperature, is heated by the heat from the ceramic heater. Ceramic heaters offer excellent heating performance, are small in size, and lightweight, and are therefore expected to overcome the aforementioned drawbacks.

[0008] However, under abnormal conditions, ceramic heaters may crack or melt. This will be explained in detail below.

[0009] Typically, a liquid of a predetermined flow rate flows over the surface of the ceramic heater (in other words, the flow path within the ceramic heater module). However, when the pump output decreases or foreign matter is introduced into the liquid, abnormal situations may occur, such as reduced flow rate or stagnation of the liquid flowing over the heater surface, when the ceramic heater starts operating (in other words, when the resistance heating element is energized). In these cases, there is a possibility that the liquid may be overheated by the ceramic heater and boil. When the liquid boils, boiling bubbles (bubbles generated by boiling) come into contact with the heater surface, thereby creating areas on the heater surface where the liquid cannot reach. These areas are not cooled by the liquid, and therefore their temperature rises sharply. At this point, for example, when the liquid comes into contact with this area due to the movement of boiling bubbles, the area is cooled abruptly by the liquid, and the ceramic heater is subjected to thermal shock. The ceramic matrix constituting the ceramic heater has relatively low thermal shock resistance. Therefore, under conditions of large thermal shock, the ceramic heater may crack.

[0010] Alternatively, when events such as reduced pump output or foreign matter contamination of the liquid occur, an abnormal situation may sometimes arise where there is no liquid on the heater surface. In this case, when the ceramic heater starts working, it is heated by the resistance heating element, but without being cooled by the liquid, the surface temperature rises sharply, resulting in a so-called dry-burning state, and the ceramic heater may melt and be damaged.

[0011] This invention was made to address the aforementioned problems. Specifically, one objective of this invention is to provide a technology that reliably prevents the cracking or melting of ceramic heaters even in the event of abnormal circumstances.

[0012] Solution for solving the problem

[0013] The control device (35) of the first ceramic heater module (1) of the present invention is used to control the ceramic heater module (1), wherein the ceramic heater module (1) comprises: a ceramic heater (20) having a ceramic substrate in which a resistive heating element is embedded; and a housing (10) that houses the ceramic heater and has an inlet (11) and an outlet (12) for the flow of a liquid medium.

[0014] The control device includes: a unit for acquiring the temperature at the outlet side of the ceramic heater module, i.e., the outlet temperature; a unit (S16, S21, S23) for determining whether a predetermined stop condition is met based on the temperature difference (ΔT1, ΔT2) between the start temperature (Ts) and the detection temperatures (T1, T2), wherein the start temperature (Ts) is the outlet temperature acquired at the energizing start time (t=0) when the resistive heating element is energized with a predetermined power (Pl), and the detection temperatures (T1, T2) are the outlet temperatures acquired at one or more specific time points after the energizing start time; and a unit (S17, S22) for stopping the energizing of the resistive heating element when the stop condition is determined to be met (S16: "Yes", S21: "Yes", S23: "Yes").

[0015] Invention Effects

[0016] The temperature difference between the start temperature (the outlet temperature at the point when energization begins) and the detection temperature (the outlet temperature obtained at one or more specific time points after the start temperature) is correlated with the flow rate of the liquid medium flowing on the surface of the ceramic heater. For example, if the temperature difference is too low (in other words, if the temperature rise of the detection temperature is lower than normal), there is a high probability that the liquid medium flowing on the heater surface will stagnate (i.e., the flow rate is zero) or that there will be no liquid medium at the heater surface. On the other hand, if the temperature difference is too high (in other words, if the temperature rise of the detection temperature is higher than normal), there is a high probability that the flow rate of the liquid medium flowing on the heater surface will be low (insufficient). The control device for the ceramic heater according to the present invention determines whether a stop condition is met based on this temperature difference, and stops energizing the resistive heating element if the stop condition is met. Therefore, the stop condition can be set based on the flow rate of the liquid medium estimated based on the temperature difference between the start temperature and the detection temperature. Thus, it is possible to appropriately determine whether an abnormal situation has occurred based on whether the stop condition is met, and reliably stop energizing the resistive heating element if an abnormal situation occurs. According to this structure, even in the event of an abnormal situation, the cracking or melting of the ceramic heater can be reliably prevented.

[0017] In one aspect of the invention, the specified power is a lower power (Pl) than the normal power (Pn) supplied during normal operation of the ceramic heater (20).

[0018] According to this structure, compared to structures that use ordinary electricity as the specified power, the heat generated per unit time by the resistive heating element can be reduced, thus suppressing the rise in the surface temperature of the ceramic heater. Therefore, even in the event of an abnormal situation, it is less likely that the liquid medium flowing on the heater surface will boil or the heater will become dry-burning. As a result, it is possible to prevent the ceramic heater from cracking or melting during the process of determining whether the stopping conditions can be met.

[0019] In one aspect of the invention, the stopping condition includes a first stopping condition, wherein the specific time point is a first reference time point from the power-on start time point (t=0) after a predetermined first time (t1), and the control device (35) determines that the first stopping condition is met when the temperature difference (ΔT1) is below a predetermined first threshold (T1th) (S16: "Yes").

[0020] When energizing the resistance heating element is initiated while the liquid medium flowing on the surface of the ceramic heater is stagnant, the temperature of the liquid medium near the ceramic substrate rises, and the liquid medium transfers heat through natural convection. Therefore, the outlet temperature (the temperature at the outlet side of the ceramic heater module) tends to rise slowly compared to normal conditions (when a prescribed flow of liquid medium flows on the heater surface). Furthermore, when energizing the resistance heating element is initiated without liquid medium on the heater surface, the temperature of the air near the ceramic substrate rises, and the air transfers heat through natural convection. Therefore, the outlet temperature tends to rise slowly compared to normal conditions. That is, when the liquid medium is stagnant or absent, the temperature difference between the start temperature and the detection temperature tends to become lower than normal. The control device for the ceramic heater module according to one aspect of the present invention determines that a first stop condition is met when the temperature difference between the start temperature and the detection temperature at a first reference time point (a time point elapsed since the energization start time) is below a first threshold. Based on this structure, it is possible to appropriately determine whether an abnormal situation of a relatively slow temperature rise at the outlet temperature (i.e., stagnant or absent liquid medium) has occurred.

[0021] Furthermore, in this specification, "the temperature difference between the start temperature and the detection temperature" is defined as the absolute value of the difference between the start temperature and the detection temperature.

[0022] In one aspect of the invention, the prescribed power is a power (Pl) that is lower than the normal power (Pn) energized during normal operation of the ceramic heater (20). If the control device (35) determines that the first stop condition is not met (S16: "No"), it maintains the prescribed power (Pl) as the power energizing the resistive heating element until a prescribed reference time point that is a time point after the first reference time point.

[0023] There are two types of abnormal situations: one where the outlet temperature rises slowly and the other where the outlet temperature rises rapidly. While the "structure for determining whether the first stop condition can be met" can determine whether an abnormal situation of the former type has occurred, it cannot determine whether an abnormal situation of the latter type has occurred. Furthermore, the latter type of abnormal situation may occur at any time depending on the power applied to the resistive heating element (i.e., the latter type of abnormal situation sometimes occurs before the first reference time point and sometimes after the first reference time point). The control device for the ceramic heater module according to one aspect of the present invention is configured to continue applying a lower power than usual to the resistive heating element until a predetermined reference time point (a time point after the first reference time point) when the first stop condition is determined not to be met. According to this structure, by continuing to apply a low power until the predetermined reference time point when the first stop condition is not met, even if the latter type of abnormal situation occurs after the first reference time point, the rise in the surface temperature of the ceramic heater can be suppressed, and as a result, the cracking of the ceramic heater can be prevented.

[0024] Furthermore, the control device can also be configured to determine, in addition to determining the first stop condition, whether an abnormal event of the latter type has occurred. In this configuration, if it is determined that an abnormal event of the latter type occurred before the first reference time point, the control device can also stop energizing the resistive heating element at the time point at which the determination was made. In this case, the determination of the first stop condition is not performed.

[0025] In one aspect of the invention, the stopping condition includes a second stopping condition. The specific time point is a plurality of time points that occur after a predetermined minute time has elapsed since the power-on start time point. When the temperature difference (ΔT2) becomes above a predetermined second threshold (T2th) (S21: "Yes", S23: "Yes"), the control device (35) determines that the second stopping condition is met. If the second stopping condition is not met, the control device (35) continues to determine the second stopping condition until a predetermined second time (t2) has elapsed since the power-on start time point.

[0026] When energizing the resistance heating element with a low flow rate of the liquid medium flowing over the heater surface, the outlet temperature tends to rise sharply compared to normal conditions. This is because when the flow rate of the liquid medium is low (i.e., the flow velocity is slow), the contact time between the liquid medium and the heater surface is longer, and the temperature of the liquid medium rises at a faster rate than normal. That is, when the flow rate of the liquid medium is low, the temperature difference between the starting temperature and the detection temperature tends to become higher than normal. The control device for the ceramic heater module according to one aspect of the present invention determines that a second stop condition is met when the temperature difference between the starting temperature and the detection temperature at a specific time point (a plurality of time points occurring every predetermined minute interval after the energization start time point) becomes a second threshold. This determination continues until a second reference time point (a time point after a second interval has elapsed from the energization start time point). Based on this structure, it is possible to appropriately determine whether an abnormal situation of a relatively rapid rise in outlet temperature (i.e., insufficient flow rate of the liquid medium) has occurred.

[0027] In one aspect of the invention, the prescribed power is a power (Pl) that is lower than the normal power (Pn) supplied during normal operation of the ceramic heater (20). When the control device (35) determines that the second stop condition is not met before the second reference time point (S21: "No"), it maintains the prescribed power (Pl) as the power supplied to the resistive heating element. When the control device (35) determines that the second stop condition is not met at the second reference time point (S23: "No"), it changes the power supplied to the resistive heating element from the prescribed power (Pl) to the normal power (Pn) (S20).

[0028] If the power supplied to the resistive heating element is immediately changed to normal power (i.e., the power value is increased) when the second stop condition is not met at any time point before the second reference time point, the surface temperature of the ceramic heater may rise sharply and potentially cause the ceramic heater to crack in the event of an abnormal situation. In contrast, according to the above structure, if the second stop condition is not met before the second reference time point (i.e., if there is no insufficient flow of the liquid medium), a low power supply continues, thus suppressing the rise in the surface temperature of the ceramic heater and preventing cracking. Furthermore, if the second stop condition is not met at the second reference time point, changing the power supplied to the resistive heating element from low power to normal power allows for proper heating of the liquid medium by the ceramic heater.

[0029] The control device (35) of the second ceramic heater module (1) of the present invention is used to control the ceramic heater module (1), wherein the ceramic heater module (1) comprises: a ceramic heater (20) having a ceramic substrate in which a resistive heating element is embedded; and a housing (10) that houses the ceramic heater and has an inlet (11) and an outlet (12) for the flow of a liquid medium.

[0030] The control device includes: a unit for acquiring the inlet temperature (T3in, T4in) at the inlet side of the ceramic heater module and the outlet temperature (T3, T4) at the outlet side of the ceramic heater module; a unit for determining whether a predetermined stop condition is met based on the temperature difference (ΔT3, ΔT4) between the inlet temperature and the outlet temperature acquired at one or more specific time points after the energization start time (t=0) when the resistive heating element is energized with a predetermined power; and a unit for stopping the energization of the resistive heating element if the stop condition is determined to be met.

[0031] In this structure, the inlet and outlet temperatures are obtained at specific time points (one or more time points after the energization start time). In other words, the inlet and outlet temperatures are obtained at the same time. The temperature difference between the inlet and outlet temperatures is correlated with the flow rate of the liquid medium flowing on the surface of the ceramic heater. The control device for the ceramic heater according to this invention determines whether a stop condition is met based on this temperature difference, and stops energizing the resistive heating element if the stop condition is met. Therefore, the stop condition can be set based on the flow rate of the liquid medium estimated based on the temperature difference between the inlet and outlet temperatures. Therefore, it is possible to appropriately determine whether an abnormal situation has occurred based on whether the stop condition is met, and reliably stop energizing the resistive heating element if an abnormal situation occurs. According to this structure, even if an abnormal situation occurs, the cracking or melting of the ceramic heater can be reliably prevented.

[0032] In one aspect of the invention, the ceramic heater (20) is a heat exchanger for heating a liquid medium flowing in a flow path within a device mounted in a vehicle.

[0033] Based on the above structure, when a ceramic heater module is used to heat liquid media flowing in the flow path of an on-board device, such as refrigerant used in a vehicle air conditioner or temperature-regulating fluid used to adjust the temperature of a vehicle battery, cracking or melting of the ceramic heater can be prevented. This expands the application range of the ceramic heater module.

[0034] In one aspect of the invention, the vehicle includes an electric vehicle, a hybrid vehicle, a plug-in hybrid vehicle, and a fuel cell vehicle.

[0035] This structure enables the use of ceramic heaters for heating the drive battery in a vehicle. Compared to PTC heaters and sheath heaters, ceramic heaters offer superior heating performance, are smaller, and lighter. Therefore, compared to structures using these heaters, battery life can be extended, layout flexibility during installation is increased, and energy efficiency can be improved.

[0036] The ceramic heater unit (100) of the present invention includes: a control device (35) for the ceramic heater module (1) of the present invention; and a ceramic heater module (1) having a ceramic heater (20) and a housing (10), wherein the ceramic heater (20) has a ceramic substrate in which a resistive heating element is embedded, the housing (10) houses the ceramic heater and has an inlet (11) and an outlet (12) for the flow of a liquid medium.

[0037] Based on this structure, a ceramic heater unit can be provided that can reliably prevent the ceramic heater from cracking or melting even in the event of an abnormal situation.

[0038] Furthermore, the control program for the first ceramic heater module involved in this invention is used to control the ceramic heater module, wherein the ceramic heater module (1) comprises: a ceramic heater (20) having a ceramic substrate in which a resistive heating element is embedded; and a housing (10) housing the ceramic heater and having an inlet (11) and an outlet (12) for the flow of a liquid medium. The control program for the ceramic heater module causes the following steps to be performed: whenever a predetermined acquisition time has elapsed, acquiring the temperature at the outlet side of the ceramic heater module, i.e., the outlet temperature; step (S11), starting to energize the resistive heating element with a predetermined power; step... (S16, S21, S23) Determine whether the prescribed stop condition is met based on the temperature difference (ΔT1, ΔT2) between the start temperature (Ts) and the detection temperature (T1, T2), wherein the start temperature (Ts) is the outlet temperature obtained at the prescribed power-on start time, and the detection temperature (T1, T2) is the outlet temperature obtained at one or more specific time points after the power-on start time; and step (S17, S22) if the stop condition is determined to be met (S16: "Yes", S21: "Yes", S23: "Yes"), stop the power supply to the resistive heating element.

[0039] According to this structure, even in the event of an abnormal situation, the cracking or melting of the ceramic heater can be reliably prevented.

[0040] The control program of the second ceramic heater module involved in this invention is used to control the ceramic heater module, wherein the ceramic heater module (1) comprises: a ceramic heater (20) having a ceramic substrate in which a resistive heating element is embedded; and a housing (10) housing the ceramic heater and having an inlet (11) and an outlet (12) for the flow of a liquid medium. The control program of the ceramic heater module causes the following steps to be performed: whenever a predetermined acquisition time has elapsed, acquiring the temperature at the inlet side of the ceramic heater module, i.e., the inlet temperature, and the temperature at the outlet side of the ceramic heater module, i.e., the outlet temperature; starting to energize the resistive heating element with a predetermined power; determining whether a predetermined stop condition is met based on the temperature difference (ΔT3, ΔT4) between the inlet temperature (T3, T4) and the outlet temperature (T3, T4) acquired at one or more specific time points after the predetermined power energizing start time (t=0); and stopping the energizing of the resistive heating element if the stop condition is determined to be met.

[0041] According to this structure, even in the event of an abnormal situation, the cracking or melting of the ceramic heater can be reliably prevented. Attached Figure Description

[0042] Figure 1 This is a partial cross-sectional schematic diagram of a heating device having a control unit including the control device involved in this embodiment and a ceramic heater.

[0043] Figure 2A It is a graph showing the time-varying temperature rise of the outlet temperature for each flow rate of the liquid flowing in the shell, based on the control device controlling the energization state of the resistive heating element under stop conditions.

[0044] Figure 2B It is a graph showing the change over time of the electrical value of the control device based on the energization state of the resistive heating element under each flow rate of the liquid flowing in the shell.

[0045] Figure 3 This is a flowchart illustrating an example of a procedure executed by the ECU to enable the control device to perform anti-breakage and anti-melting control.

[0046] Figure 4A This is a graph showing the time-varying temperature difference between the inlet and outlet temperatures of a modified example where the control device controls the energization state of the resistive heating element based on a stop condition for each flow rate of the liquid flowing in the shell.

[0047] Figure 4BIt is a graph showing the change over time of the electrical value of the control device based on the energization state of the resistive heating element under each flow rate of the liquid flowing in the shell. Detailed Implementation

[0048] The embodiments of the present invention will now be described with reference to the accompanying drawings. Figure 1 This is a schematic structural diagram of a heating device 100 having the control device 35 according to this embodiment. Figure 1 As shown, the heating device 100 includes a ceramic heater module 1 and a control unit 30 including a control device 35. This heating device 100 is configured to heat a liquid to a predetermined temperature via the ceramic heater module 1. For ease of explanation, in... Figure 1 The ceramic heater module 1 is shown in a partial cross-sectional view. Furthermore, the heating device 100 is equivalent to an example of a "ceramic heater unit".

[0049] The ceramic heater module 1 includes a housing 10 and a ceramic heater 20. The housing 10 is a component for forming a flow path for the liquid heated by the ceramic heater 20. The housing 10 is formed as a cylinder closed at both ends. Figure 1 The section containing the axis is represented. A circular hole 11 extending axially is formed in the center of the upper end wall of the housing 10. Additionally, on the side peripheral walls of the housing 10... Figure 1 The upper part of the housing 10 is provided with a cylindrical outlet passage 12. The outlet pipe 42 is connected to the outlet passage 12. Therefore, the internal space of the housing 10 is connected to the outlet pipe 42 via the outlet passage 12. Liquid discharged from the housing 10 flows to the outlet pipe 42. The circular hole 11 is an example of the "inlet" of the housing 10, and the outlet passage 12 is an example of the "outlet" of the housing 10.

[0050] The ceramic heater 20 has a resistance heating element and a ceramic substrate. The resistance heating element is a component that heats up when electricity is applied, and is composed of long wires to form a predetermined pattern. Tungsten wire can be exemplified as a resistance heating element, for example. The resistance heating element is embedded in the ceramic substrate. The ceramic substrate is a component used to heat the object being heated, and is heated by the resistance heating element embedded therein. The ceramic substrate is formed of ceramic. For example, the ceramic substrate is formed of alumina.

[0051] The ceramic heater 20 is configured as a generally cylindrical shape with openings at both ends. The cylindrical ceramic heater 20 can be manufactured, for example, as follows: A laminate is formed by clamping a resistance heating element shaped into a predetermined pattern between two ceramic blanks, and this laminate is wound around the cylindrical ceramic body. Then, by firing the ceramic body with the laminate wound around it, a cylindrical ceramic heater 20 having a resistance heating element and a ceramic substrate in which the resistance heating element is embedded can be produced. This ceramic heater 20 has a base 21, a main body 22, and a flange 23. The base 21 and the main body 22 are continuously arranged along the axial direction. The base 21 extends from one end of the generally cylindrical ceramic heater 20 (at... Figure 1 It is formed at the upper end of the base 21. Figure 1 The upper part (middle) is connected to the inlet pipe 41. Liquid heated by the ceramic heater 20 is introduced from the inlet pipe 41 toward the interior space of the base 21.

[0052] The main body 22 is composed of cylindrical portions excluding the base 21. For example... Figure 1 As shown, the axial length of the main body 22 is longer than the axial length of the base 21. Furthermore, the base 21 and the main body 22 are coaxially cylindrical, with their internal spaces interconnected axially. Additionally, an annular flange 23 is installed on the outer periphery of the boundary between the base 21 and the main body 22, extending radially outward. A first electrode 24 and a second electrode 25 are formed on the outer peripheral surface of the base 21. Both the first electrode 24 and the second electrode 25 are made of conductive materials such as metal.

[0053] The axial length of the main body 22 is shorter than the axial length of the housing 10. Furthermore, the outer diameter of the main body 22 is approximately equal to the diameter of the circular hole 11 formed in the center of the upper end wall of the housing 10. The main body 22 is inserted into the interior space of the housing 10 from its front end side through the circular hole 11. Thus, the main body 22 is coaxially disposed within the interior space of the housing 10. At this time, the base 21 protrudes upwards from the upper end of the housing 10, and the flange 23 rests on the upper end surface of the housing 10. Moreover, the gap between the upper outer periphery of the main body 22 and the circular hole 11 is liquid-tightly sealed by a sealing member or the like.

[0054] The resistance heating element of the ceramic heater 20 is embedded in a predetermined pattern primarily within the ceramic substrate constituting the main body 22. Both ends of the resistance heating element are led out to the base 21, and each end of the resistance heating element is connected to a first electrode 24 and a second electrode 25 formed on the surface of the base 21. Therefore, by applying a predetermined voltage between the first electrode 24 and the second electrode 25, the resistance heating element is energized (current flows through it).

[0055] The control unit 30 includes a first conductive member 31, a second conductive member 32, a power supply device 33, an ammeter 34, a control device 35, an inlet temperature sensor 36, and an outlet temperature sensor 37.

[0056] The first conductive member 31 and the second conductive member 32 are each composed of a conductor having one end and the other end. Leads can be exemplified as the first conductive member 31 and the second conductive member 32. One end of the first conductive member 31 is connected to the first electrode 24, and one end of the second conductive member 32 is connected to the second electrode 25. Furthermore, the other ends of the first conductive member 31 and the second conductive member 32 are respectively connected to a power supply device 33. The power supply device 33 is configured to apply a predetermined voltage between the first conductive member 31 (first electrode 24) and the second conductive member 32 (second electrode 25). Additionally, a galvanometer 34 is inserted and installed in the middle of the first conductive member 31. The galvanometer 34 measures the current flowing in the first conductive member 31. The galvanometer 34 can also be inserted and installed in the second conductive member 32.

[0057] An inlet temperature sensor 36 is installed on the inlet pipe 41 and is capable of detecting the temperature of the liquid flowing through the inlet pipe 41. As described above, the inlet pipe 41 is connected to the front end of the base 21. Therefore, it can also be said that the inlet temperature sensor 36 detects the "temperature at the inlet side of the ceramic heater module 1". Hereinafter, the "temperature at the inlet side of the ceramic heater module 1" will also be referred to as the "inlet temperature". In addition, the inlet temperature can also be described as the "temperature on the side of the ceramic heater module 1 where the liquid is introduced".

[0058] An outlet temperature sensor 37 is installed in the outlet pipe 42 and is capable of detecting the temperature of the liquid flowing in the outlet pipe 42. As described above, the outlet pipe 42 is connected to the outlet passage 12. Therefore, the outlet temperature sensor 37 can also be said to detect the "temperature on the outlet side of the ceramic heater module 1". Hereinafter, the "temperature on the outlet side of the ceramic heater module 1" will also be referred to as the "outlet temperature". In addition, the outlet temperature can also be said to be the "temperature on the side of the ceramic heater module 1 where the liquid is discharged".

[0059] The control device 35 controls the ceramic heater 20. Specifically, the control device 35 controls the energizing state (start / stop of energizing, power value) of the resistive heating element of the ceramic heater 20, so that the heating temperature of the liquid heated by the ceramic heater 20 is a predetermined target temperature. The control device 35 has an ECU 351 equipped with a CPU, ROM, and RAM. Furthermore, ECU is an abbreviation for Electronic Control Unit.

[0060] The ROM of ECU 351 contains a pre-stored program for controlling the energizing state of the resistive heating element. The CPU of ECU 351 reads the program from the ROM, expands it in RAM, and executes it.

[0061] Ammeter 34 sends a current signal to control device 35, indicating the measured current value. ECU 351 of control device 35 acquires the current flowing in the first conductive member 31 based on the current signal received from ammeter 34. Additionally, inlet temperature sensor 36 detects the inlet temperature (typically the temperature of the liquid flowing in inlet piping 41) and sends a temperature signal to control device 35 indicating the detected temperature. ECU 351 of control device 35 acquires the inlet temperature based on the temperature signal received from inlet temperature sensor 36. Similarly, outlet temperature sensor 37 detects the outlet temperature (typically the temperature of the liquid flowing in outlet piping 42) and sends a temperature signal to control device 35 indicating the detected temperature. ECU 351 of control device 35 acquires the outlet temperature based on the temperature signal received from outlet temperature sensor 37. Control device 35 can also receive signals other than those described above. Control device 35 is configured to control power supply device 33 based on various input signals (current signals, temperature signals, etc.). The energizing state of the resistive heating element of the ceramic heater 20 is controlled by the power supply device 33 controlled by the control device 35. Alternatively, the power supply device 33 can be embedded within the control device 35.

[0062] In this embodiment, the heating device 100 with the above-described structure heats a liquid medium flowing in a flow path within a device mounted in a vehicle. In this case, the ceramic heater 20 functions as a heat exchanger for heating the liquid medium flowing in the flow path within the device mounted in the vehicle. Examples of devices mounted in a vehicle include vehicle air conditioning systems and temperature control devices for vehicle batteries. Examples of flow paths within a vehicle device include flow paths in the refrigerant circuit of a vehicle air conditioning system and flow paths formed in the temperature control device for a vehicle battery. In this case, the ceramic heater 20 functions as a heat exchanger for heating the refrigerant flowing in the refrigerant circuit of the vehicle air conditioning system, or for heating a temperature-regulating fluid flowing in the flow path formed in the temperature control device for a vehicle battery. Furthermore, vehicles include electric vehicles, hybrid vehicles, plug-in hybrid vehicles, and fuel cell vehicles.

[0063] In the heating device 100 with the above structure, the liquid, which is the heated body, is introduced into the interior of the base 21 of the ceramic heater 20 from the inlet pipe 41, and is introduced into the interior space of the main body 22 from the base 21.

[0064] Liquid introduced into the internal space of the main body 22, such as Figure 1 As shown by the arrow, the liquid flows downwards within the main body 22 and exits from the opening at the front end (lower end) of the main body 22. The space between the inner wall surface of the side peripheral wall of the housing 10 and the outer wall surface of the main body 22 is as follows... Figure 1 As indicated by the arrow, the liquid flows upwards and is discharged to the outlet pipe 42 via the outlet passage 12 located at the upper part of the housing 10. In this way, the housing 10 forms a flow path for the liquid that is introduced (supplied) from the inlet pipe 41 and discharged to the outlet pipe 42.

[0065] As the liquid flows within the housing 10, the control device 35 controls the power supply device 33 to apply a predetermined voltage between the first conductive member 31 (first electrode 24) and the second conductive member 32 (second electrode 25). This energizes the resistive heating element. The resistive heating element heats up due to the energization. The heating of the resistive heating element heats the main body 22. Therefore, the liquid flowing on the surface (inner and outer peripheral walls) of the heated main body 22 is heated by the main body 22. Thus, the liquid is heated by the heating device 100 (ceramic heater 20), and the heated liquid is discharged to the outlet pipe 42.

[0066] The control device 35 obtains the temperature of the liquid before it is heated by the heating device 100 as the inlet temperature based on the temperature signal sent from the inlet temperature sensor 36 installed on the inlet pipe 41. Similarly, the control device 35 obtains the temperature of the liquid after it has been heated by the heating device 100 as the outlet temperature based on the temperature signal sent from the outlet temperature sensor 37 installed on the outlet pipe 42. Then, the control device 35 controls the power supply device 33 to make the outlet temperature match the target temperature. Thus, the temperature of the liquid can be controlled so that the temperature of the liquid discharged into the outlet pipe 42 is the predetermined target temperature. In this case, the control device 35 can control the liquid temperature to make the outlet temperature close to the target temperature through PI control based on the deviation between the outlet temperature and the target temperature.

[0067] When the heating device 100 is operating normally, the entire surface (inner and outer peripheral walls) of the main body 22 of the ceramic heater 20 is in contact with the liquid introduced into the heating device 100. Therefore, the main body 22 is heated by the resistance heating element and cooled by the liquid flowing over its surface. Consequently, the surface temperature of the main body 22 rises sharply immediately after the resistance heating element is energized, but quickly approaches a temperature at which heating and cooling have reached equilibrium, eventually remaining at a substantially constant temperature. Furthermore, the liquid is heated by the main body 22, whose surface temperature is maintained at a substantially constant temperature.

[0068] Here, a pump (not shown) is connected to the heating device 100, and the flow rate of the liquid supplied to the heating device 100 depends on the pump's performance. When an abnormal situation occurs, such as a decrease in pump output for some reason or the introduction of foreign matter into the liquid, the flow rate of the liquid flowing inside the housing 10 (i.e., the liquid flowing on the surface of the ceramic heater 20 (strictly speaking, the main body 22)) may sometimes decrease or stagnate when the heating device 100 starts operating (in other words, when the resistance heating element is energized). The former flow rate may be, for example, 1 L / min to 2 L / min, while the latter flow rate may be 0 L / min. In these cases, the heat supplied to the liquid by the main body 22 may sometimes increase, causing the liquid to boil. When the liquid boils inside the housing 10, boiling bubbles are generated inside the housing 10. When the generated boiling bubbles come into contact with the surface of the main body 22, the area in contact with the boiling bubbles on the surface of the main body 22 is not in liquid contact, and therefore this area is not cooled by the liquid. As a result, the temperature of this area rises sharply. At this time, when the liquid comes into contact with the area again due to the movement of boiling bubbles, the area is cooled by the liquid and experiences thermal shock. The ceramic matrix constituting the main body 22 has relatively low thermal shock resistance. Therefore, under the action of a large thermal shock, the ceramic heater 20 (main body 22) may crack.

[0069] Alternatively, when the aforementioned abnormal situation occurs, sometimes the liquid is not introduced into the inlet pipe 41, resulting in the absence of liquid within the housing 10 (i.e., the ceramic heater 20). In this case, when the heating device 100 starts operating, the main body 22 is heated due to the heat generated by the resistance heating element, but is not cooled by the liquid. Therefore, the surface temperature rises sharply, resulting in a so-called dry-burning state, and the ceramic heater 20 may melt.

[0070] Therefore, it is desirable for the control device 35 to control the energization of the resistive heating element so as to prevent the ceramic heater 20 from cracking or melting due to abnormal events. Therefore, in this embodiment, the control device 35 is configured to determine whether a predetermined stop condition is met, and stop energizing the resistive heating element if the stop condition is met. This will be explained in detail below.

[0071] The stopping conditions include the first stopping condition and the second stopping condition below.

[0072] (First Stop Condition) The temperature difference ΔT1 between the start temperature Ts and the detection temperature T1 is below the specified threshold T1th.

[0073] (Second Stop Condition) The temperature difference ΔT2 between the start temperature Ts and the detection temperature T2 is greater than or equal to the specified threshold T2th.

[0074] Here, the starting temperature Ts is the outlet temperature at the point when energizing the resistive heating element begins (hereinafter also referred to as the "energizing start time point"). Additionally, the detection temperature T1 is the outlet temperature at the point where a predetermined time t1 has elapsed since the energizing start time point (hereinafter also referred to as the "first reference time point"). The detection temperature T2 is the outlet temperature at multiple time points that occur after the energizing start time point each time a predetermined minute tm has elapsed. In other words, the detection temperature T2 is the outlet temperature periodically obtained at time intervals of minute tm after the energizing start time point. The determination of whether the second stopping condition is met is performed up to the point where a predetermined time t2 has elapsed since the energizing start time point (hereinafter also referred to as the "second reference time point"). That is, the determination of the first stopping condition is performed only once at the first reference time point, while the determination of the second stopping condition is performed every minute tm, up to multiple times up to the second reference time point. Time t2 is greater than time t1 (t2 > t1), and the threshold T2th is greater than the threshold T1th (T2th > T1th). In this embodiment, during the period of determining whether these stopping conditions are met, the resistive heating element is energized with 2kW of power (described later). Additionally, under normal conditions, liquid is supplied to the housing 10 at a flow rate of 5L / min. Based on this operating environment, time t1 is set to 4 seconds, and time t2 is set to 10 seconds. Furthermore, threshold T1th is set to 1.0°C, and threshold T2th is set to 15.0°C. These values ​​can be determined based on experiments or simulations, but different values ​​may also be used. Furthermore, times t1 and t2 are examples of "first time" and "second time," respectively, and thresholds T1th and T2th are examples of "first threshold" and "second threshold," respectively. Additionally, "first reference time point" and "multiple time points that occur every minute time tm after the energization start time point" are examples of "specific time points."

[0075] When either the first stop condition or the second stop condition is met, the control device 35 determines that an abnormal situation has occurred and stops energizing the resistive heating element. On the other hand, the control device 35 energizes the resistive heating element with preheating power P1 until either the first stop condition or the second stop condition is met. Preheating power P1 is a power with a value lower than the normal power Pn (the power energized to the resistive heating element during normal operation of the ceramic heater 20) (P1 < Pn). Furthermore, "normal operation of the ceramic heater 20" means, in other words, the heating device 100 is operating normally. That is, in this embodiment, the control device 35 is configured to selectively energize the resistive heating element with the normal power Pn and the preheating power P1, which is lower than the normal power Pn. In this embodiment, the control device 35 energizes 2kW of power as preheating power P1 and 6kW of power as normal power Pn, but the values ​​of P1 and Pn are not limited to these. If the second stop condition is not met until the second reference time point is reached, the control device 35 changes the power value of the resistive heating element from the preheating power P1 to the normal power Pn at the second reference time point.

[0076] The first stopping condition is met when the temperature difference ΔT1 (=|starting temperature Ts - detection temperature T1|) at the first reference time point is below the threshold T1th. When the resistance heating element is energized while the liquid flowing inside the housing 10 is stagnant (i.e., the flow rate is 0 L / min), the temperature of the liquid near the ceramic substrate (especially the main body 22) rises, and the liquid transfers heat through natural convection. Therefore, the outlet temperature tends to rise slowly compared to normal conditions. Furthermore, when the resistance heating element is energized when there is no liquid inside the housing 10, the temperature of the air near the ceramic substrate (especially the main body 22) rises, and the air transfers heat through natural convection. Therefore, the outlet temperature tends to rise slowly compared to normal conditions. Moreover, in this case, there is no liquid in the outlet pipe 42, so the outlet temperature sensor 37 detects the temperature of the air inside the outlet pipe 42 as the outlet temperature.

[0077] That is, when liquid is present or absent, the temperature difference ΔT1 tends to be lower than normal. Therefore, the threshold T1th is set to a value that is greater than or equal to the temperature difference ΔT1 when liquid is present or absent, but less than the temperature difference ΔT1 when liquid is present or absent. In this embodiment, liquid is supplied to the housing 10 at a flow rate of approximately 5 L / min under normal conditions, and as described above, 2 kW of electricity is supplied as preheating power P1. Based on this operating environment, time t1 is set to 4 seconds, and threshold T1th is set to 1.0°C. By setting time t1 and threshold T1th in this way, the first stop condition is only met when liquid is present or absent. Furthermore, time t1 and threshold T1th can be determined based on experiments or simulations, but different values ​​can also be used. In addition, time t1 and threshold T1th can also be appropriately changed when the operating environment is changed. Time t1 and threshold T1th are examples of "first time" and "first threshold," respectively.

[0078] The second stopping condition is established when the temperature difference ΔT2 (=|starting temperature Ts - detection temperature T2|) calculated at multiple time points after a small time tm after the energization start time is greater than or equal to the threshold T2th. When energizing the resistive heating element is started when the flow rate of the liquid flowing in the housing 10 is low (i.e., the flow rate is 1L / min to 2L / min), the outlet temperature tends to rise sharply compared to normal. This is because when the liquid flow rate is low (i.e., the flow rate is slow), the contact time between the liquid and the surface of the ceramic heater 20 is longer, and the liquid temperature rises at a faster rate than normal. That is, when the liquid flow rate is low, the temperature difference ΔT2 tends to become higher than normal. Therefore, the threshold T2th is set to a value that is lower than the temperature difference ΔT2 when the liquid flow rate is low but greater than the temperature difference ΔT2 when the liquid flow rate is normal. In addition, even when the liquid flow rate is within the normal range, the outlet temperature rises as the energization time increases. Therefore, time t2 (the longest time for determining the second stop condition) is set such that the increase in outlet temperature of the liquid with a flow rate within the normal range from the start of energization is less than the threshold T2th. Based on the above operating environment, time t2 is set to 10 seconds, and threshold T2th is set to 15.0°C. By setting time t2 and threshold T2th in this way, the second stop condition is only established when the liquid flow rate is low. Furthermore, time t2 and threshold T2th can be determined based on experiments or simulations, but different values ​​can also be used. In addition, time t2 and threshold T2th can be appropriately changed when the operating environment changes. Time t2 and threshold T2th are examples of "second time" and "second threshold," respectively.

[0079] When energizing the resistive heating element begins, the control device 35 starts determining the second stop condition. If the second stop condition is determined to be false, the control device 35 determines that no abnormal situation has occurred and maintains the power supply to the resistive heating element at preheating power P1. When the first reference time point is reached during the determination of the second stop condition, the control device 35 determines the first stop condition. If the first stop condition is determined to be false, the control device 35 determines that no abnormal situation has occurred and continues to maintain the preheating power P1. After the first reference time point has passed, the control device 35 also continues to determine the second stop condition. If the second stop condition is determined to be false, the preheating power P1 continues to be maintained. Then, when the second stop condition is determined to be false at the second reference time point, the control device 35 determines that no abnormal situation has occurred and changes the power supply to the resistive heating element from the preheating power P1 to the normal power Pn.

[0080] Figure 2A and Figure 2B This is a graph showing the temperature rise of the outlet temperature and the electrical power P when the control device 35 controls the energization state of the resistive heating element based on the first stop condition and the second stop condition. Figure 2A The horizontal axis of the graph represents the time t (seconds) that has elapsed since the start of energization, and the vertical axis represents the temperature rise (°C) of the outlet temperature since the start of energization (in other words, the temperature difference from the starting temperature Ts). Figure 2B The horizontal axis of the chart represents the... Figure 2A For the same time t (seconds), the vertical axis represents the electrical power P (kW) applied to the resistive heating element. These graphs show the behavior of liquids at nine flow rates from 0 L / min to 25 L / min.

[0081] Control device 35 energizes the resistance heating element with 2kW preheating power P1 at time t=0 (refer to...). Figure 2B Therefore, as Figure 2A As shown, when the flow rate is 1 L / min or higher, the outlet temperature increases over time (reference lines L1 to L8). In particular, when the flow rate is 1 L / min and 2 L / min (i.e., low flow rate), the rate of increase in outlet temperature is more rapid compared to when the flow rate is 3 L / min or higher (reference lines L1 and L2). On the other hand, when the flow rate is 0 L / min (i.e., stagnant flow), the rate of increase in outlet temperature is extremely slow (reference line L0).

[0082] Control device 35 determines whether the second stopping condition (ΔT2 ≥ 15.0℃) is met whenever a small time tm elapses from time t = 0 (in other words, at multiple time points at each small time tm elapses). The vertical axis values ​​of the lines L0 to L8 at the aforementioned multiple time points are equal to the temperature difference ΔT2 between the starting temperature Ts and the detection temperature T2. This determination is performed up to time t = 10. Additionally, control device 35 determines whether the first stopping condition (ΔT1 ≤ 1.0℃) is met at time t = 4. The vertical axis values ​​of the lines L0 to L8 at time t = 4 are equal to the temperature difference ΔT1 between the starting temperature Ts and the detection temperature T1. In this example, ΔT1 ≤ 1.0℃ only when the flow rate is 0 L / min, and ΔT1 > 1.0℃ only when the flow rate is 1 L / min or higher. Therefore, the control device 35 determines that the first stop condition is met only when the flow rate is 0 L / min, and stops energizing the resistive heating element at time t = 4. When the flow rate is 1 L / min or higher, it maintains a preheating power of 2 kW P1 (refer to) during the period t ≥ 4. Figure 2B Furthermore, when the flow rate was 0 L / min, the temperature rise measurement was terminated at time t = 5.

[0083] During the period t≥4, when the flow rate is 1L / min, ΔT2≥15.0℃ at time t=ta; when the flow rate is 2L / min, ΔT2≥15.0℃ at time t=tb(>ta). On the other hand, when the flow rate is 3L / min or higher, ΔT2<15.0℃ up to time t=10. Therefore, when the flow rate is 1L / min, the control device 35 determines that the second stop condition is met at time t=ta, and stops energizing the resistive heating element at that time (see reference). Figure 2B Therefore, as Figure 2A As shown, at a flow rate of 1 L / min, after a time lag from the point of energization shutdown, the rate of increase in outlet temperature slows down (reference line L1). Although not shown in the graph, it is presumed that the outlet temperature then decreases. At a flow rate of 2 L / min, the control device 35 determines that the second stop condition is met at time t = tb, and stops energizing the resistive heating element at this time (reference line L1). Figure 2B Therefore, as Figure 2A As shown, when the flow rate is 2 L / min, it decreases at a certain time point where t > tb (reference line L2). On the other hand, when the flow rate is 3 L / min or higher, the control device 35 maintains a preheating power of 2 kW P1 during the period t < 10, and changes the power value to a normal power of 6 kW Pn at the time point t = 10 (reference line L2). Figure 2B Therefore, as Figure 2AAs shown, when the flow rate is above 3L / min, after a certain time lag following the change in power value, the outlet temperature rises at a higher rate than before (reference lines L3 to L8).

[0084] In addition, although the illustration is omitted, the temperature rise at the outlet was measured by energizing the preheating power P1 even when there was no liquid inside the casing 10. As a result, the temperature rise was relatively slow, and therefore the first stopping condition was met at t=4.

[0085] The above describes how, when liquid remains in the housing 10 or when no liquid is present, the energization of the resistive heating element is stopped based on the fulfillment of the first stopping condition, and when the flow rate of liquid flowing in the housing 10 is low, the energization of the resistive heating element is stopped based on the fulfillment of the second stopping condition.

[0086] Figure 3 This is a flowchart illustrating an example of a procedure executed by the ECU 351 of the control device 35 in order to enable the control device 35 to perform anti-crack and anti-melting control.

[0087] Start execution Figure 3 In the case of the procedure shown, ECU 351 first in Figure 3 In step 11 (hereinafter, the step number will be abbreviated as S), the preheating power P1 (=2kW) is supplied to the resistance heating element. Furthermore, upon starting the supply of power to the resistance heating element, the ECU 351 performs temperature control (e.g., PI control) on the liquid heated by the heating device 100. A description of the procedure for performing this temperature control is omitted.

[0088] Next, ECU 351 obtains the outlet temperature at the start time of power-on from outlet temperature sensor 37 as the start temperature Ts (S12). Then, ECU 351 begins counting by the timer (S13). Next, ECU 351 performs processes S14 to S17 and processes S18 to S24 in parallel. Each process will be described in turn below. In S14, ECU 351 determines whether the elapsed time t of the timer has reached time t1 (=4 seconds). If t<t1 (S14: “No”), the process returns to S14. If t=t1 is true during this process (S14: “Yes”), the process proceeds to S15.

[0089] In S15, ECU 351 obtains the outlet temperature at time t = t1 from outlet temperature sensor 37 as the detection temperature T1. Next, ECU 351 determines whether the temperature difference ΔT1 between the start temperature Ts and the detection temperature T1 is below the threshold T1th (= 1.0℃) (i.e., whether the first stop condition is met) (S16). If ΔT1 ≤ T1th (S16: "Yes"), the process proceeds to S17. In S17, ECU 351 determines that an abnormal situation has occurred (liquid stagnation or absence) and stops energizing the resistive heating element. This prevents liquid boiling or dry burning of the ceramic heater 20 in advance, reliably preventing the ceramic heater from cracking or melting. On the other hand, if ΔT1 > T1th (S16: "No"), ECU 351 terminates the execution of processes S14 to S17. At this time, ECU 351 maintains the energizing power to the resistive heating element at the preheating power P1.

[0090] In contrast, in S18, ECU 351 determines whether the elapsed time t of the timer satisfies t = ntm (n: an integer greater than or equal to 1) (in other words, whether the current time point is the time point that arrives every minute time tm since the start of power-on). If t = ntm (S18: "No"), the process returns to S18. If t = ntm is true during this process (S18: "Yes"), the process proceeds to S19. In S19, ECU 351 obtains the outlet temperature at the time point t = ntm from the outlet temperature sensor 37 as the detection temperature T2. Next, ECU 351 determines whether the elapsed time t has reached time t2 (=10 seconds) (S20). If t < t2 (S20: "No"), ECU 351 determines whether the temperature difference ΔT2 between the start temperature Ts and the detection temperature T2 is greater than or equal to the threshold T2th (=15.0℃) (i.e., whether the second stop condition is met) (S21). If ΔT2 < T2th (S21: "No"), the process returns to S18. If ΔT2 ≥ T2th is true during the process from S18 to S21 (S21: "Yes"), the process proceeds to S22.

[0091] In S22, ECU 351 determines that an abnormal situation has occurred (insufficient liquid flow) and stops energizing the resistive heating element. This prevents the liquid from boiling in advance, reliably preventing the ceramic heater from breaking. Afterwards, ECU 351 terminates the execution of processes S18 to S24. On the other hand, if t = t2 is met during the processes of S18 to S21 (S20: "Yes"), the process proceeds to S23. In S23, ECU 351 determines whether ΔT2 ≥ T2th is met (i.e., whether the second stop condition is met). If ΔT2 ≥ T2th (S23: "Yes"), ECU 351 stops energizing the resistive heating element as described in S22. Conversely, if ΔT2 < T2th (S23: "No"), the process proceeds to S24. In S24, ECU 351 changes the power value energizing the resistive heating element from preheating power P1 to normal power Pn (=6kW). Afterwards, ECU 351 terminates the execution of processes S18 to S24. The timer value is initialized at the end of process S22. Furthermore, if the energization of the resistive heating element is stopped through process S17 or S22, the execution of temperature control of the liquid heated by heating device 100 also stops.

[0092] As explained above, the control device 35 according to this embodiment can appropriately determine whether an abnormal situation has occurred based on whether a first stop condition or a second stop condition is met, and can reliably stop the power supply to the resistive heating element in the event of an abnormal situation. Therefore, even if an abnormal situation occurs, the cracking or melting of the ceramic heater 20 can be reliably prevented.

[0093] In particular, in this embodiment, during the period of determining whether the first and second stop conditions can be met, a preheating power P1, which is lower than the normal power Pn, is applied to the resistance heating element. Therefore, the rise in the surface temperature of the ceramic heater 20 can be suppressed, and even in the event of an abnormal situation, it is less likely that the liquid will boil or the ceramic heater 20 will become dry-burning. As a result, it is possible to prevent the ceramic heater 20 from cracking or melting during the process of determining whether the first and second stop conditions can be met.

[0094] The embodiments of the present invention have been described above, but the present invention is not limited to the above embodiments. Various modifications can be made as long as they do not depart from the purpose of the present invention.

[0095] For example, in one embodiment, when the heating device 100 starts operating, a preheating power P1 is supplied to the resistance heating element, but this structure is not limited to this. The control device 35 may also supply a normal power Pn to the resistance heating element from the time point when the heating device 100 starts operating. In this case, the values ​​of time t1, t2, thresholds T1th, T2th, etc., can be adjusted so that the ceramic heater 20 will not crack or melt due to abnormal events during the determination period of whether the first stop condition and the second stop condition can be met.

[0096] Alternatively, the control device 35 may be configured to determine only one of the first stop condition and the second stop condition.

[0097] Furthermore, as a variation, the determination of whether the stop condition is met can also be based on the temperature difference between the inlet and outlet temperatures at one or more specific time points after the energization start time. In this case, for example, a third stop condition and a fourth stop condition can be set to replace the first and second stop conditions.

[0098] The third stopping condition is met when the temperature difference ΔT3 between the inlet temperature T3in and the outlet temperature T3 is below a predetermined threshold T3th. Here, the inlet temperature T3in and the outlet temperature T3 are the inlet and outlet temperatures obtained at a predetermined time t3 elapsed since the start of energization (hereinafter also referred to as the "third reference time point"). Time t3 and the threshold T3th can be determined experimentally or through simulation. These values ​​can be the same as or different from time t1 and threshold T1th, respectively.

[0099] Furthermore, the fourth stopping condition is established when the temperature difference ΔT4 between the inlet temperature T4in and the outlet temperature T4 is greater than or equal to a predetermined threshold T4th. Here, the inlet temperature T4in and the outlet temperature T4 are the inlet and outlet temperatures obtained at multiple time points after the start of energization, each elapsed by a predetermined minute time tm2. The minute time tm2 can be the same as or different from the minute time tm. The determination of whether the fourth stopping condition is valid continues up to a time point where a predetermined time t4 has elapsed since the start of energization (hereinafter also referred to as the "fourth reference time point"). That is, the determination of the third stopping condition is performed only once at the third reference time point, while the determination of the fourth stopping condition can be performed multiple times each elapsed by a minute time tm2, up to the fourth reference time point. Time t4 is greater than time t3 (t4 > t3), and the threshold T4th is greater than the threshold T3th (T4th > T3th). Time t4 and the threshold T4th can be determined based on experiments or simulations. These values ​​can be the same as or different from time t2 and threshold T2th, respectively. In addition, the "third reference time point" and "multiple time points that arrive after the power-on start time point each time a tiny time tm2 elapses" are both examples of "specific time points".

[0100] Figure 4A and Figure 4B This is a graph showing the temperature difference between the inlet and outlet temperatures and the electrical power P when the control device 35 controls the energization state of the resistive heating element based on the third and fourth stop conditions. Figure 4A The horizontal axis of the graph represents the time t (seconds) elapsed from the start of energization, and the vertical axis represents the temperature difference (°C) between the inlet and outlet temperatures after the start of energization. Figure 4B The horizontal and vertical axes of the chart are... Figure 2B Same. In this example, let t3 = t1 (= 4 seconds), t4 = t2 (= 10 seconds), T3th = T1th (= 1.0℃), and T4th = T2th (= 15.0℃). See Figure 4 and... Figure 4B As shown, the temperature difference between lines L10 and L18 and the behavior of the electric current P are related to... Figure 2A and Figure 2B The temperature difference and electrical P behavior of lines L1 to L8 are very similar. Specifically, the third stopping condition is only true when the flow rate is 0 L / min (see reference). Figure 4A Therefore, control device 35 stops energizing the resistive heating element at time t=4 (refer to...). Figure 4B Additionally, the fourth stopping condition is met at time t = tc when the flow rate is 1 L / min, and at time t = td (> tc) when the flow rate is 2 L / min (see reference). Figure 4ATherefore, in the former case, control device 35 stops energizing the resistive heating element at time t = tc, and in the latter case, stops energizing the resistive heating element at time t = td (refer to...). Figure 4B According to this structure, it also achieves the same effect as the embodiment. Furthermore, the inlet temperatures T3in and T4in can also be the inlet temperatures obtained at the start of energization.

[0101] In this variation, Figure 3 The flowchart can be replaced as follows. Specifically, after processing S11, the process skips S12 and proceeds to S13. S14 can be replaced with "t=t3?", S15 can be replaced with "get inlet temperature T3in, get outlet temperature T3", S16 can be replaced with "ΔT3≤T3th?", S19 can be replaced with "get inlet temperature T4in, get outlet temperature T4", S20 can be replaced with "t=t4", and S21 and S23 can be replaced with "ΔT4≥T4th?".

[0102] Furthermore, this disclosure can include the following methods.

[0103] [1] A control device for a ceramic heater module, used to control the ceramic heater module, wherein the ceramic heater module comprises: a ceramic heater having a ceramic substrate with an embedded resistive heating element; and a housing housing the ceramic heater and having an inlet and an outlet for the flow of a liquid medium, the control device for the ceramic heater module comprising:

[0104] A unit for obtaining the temperature at the outlet side of the ceramic heater module, i.e., the outlet temperature;

[0105] A unit that determines whether a predetermined stop condition is met based on the temperature difference between the start temperature and the detection temperature, wherein the start temperature is the outlet temperature obtained at the energizing start time when a predetermined power is applied to the resistive heating element, and the detection temperature is the outlet temperature obtained at one or more specific time points after the energizing start time; and

[0106] A unit that stops energizing the resistive heating element when the stopping condition is determined to be met.

[0107] [2] The control device for the ceramic heater module according to [1], wherein,

[0108] The specified power is lower than the normal power supplied when the ceramic heater is in normal operation.

[0109] [3] The control device for the ceramic heater module according to [1] or [2], wherein,

[0110] The stopping conditions include a first stopping condition.

[0111] The specific time point is the first reference time point that has elapsed for a predetermined first time since the power-on start time point.

[0112] When the temperature difference is below a predetermined first threshold, the control device determines that the first stop condition has been met.

[0113] [4] The control device for the ceramic heater module according to [3], wherein,

[0114] The specified power is lower than the normal power supplied during the normal operation of the ceramic heater.

[0115] If the control device determines that the first stop condition is not met, it maintains the specified power as the power to energize the resistive heating element until a specified reference time point, which is a time point after the first reference time point, is reached.

[0116] [5] A control device for a ceramic heater module according to any one of [1] to [4], wherein,

[0117] The stopping condition includes a second stopping condition.

[0118] The specific time points are multiple time points that occur after the power-on start time point, each time a predetermined minute interval has elapsed.

[0119] The control device determines that the second stop condition is met when the temperature difference becomes above a predetermined second threshold.

[0120] If the second stop condition is not met, the control device continues to determine the second stop condition until a second reference time point, which is a predetermined second time, has elapsed since the power-on start time.

[0121] [6] The control device for the ceramic heater module according to [5], wherein,

[0122] The specified power is lower than the normal power supplied during the normal operation of the ceramic heater.

[0123] If the control device determines that the second stop condition is not met before the second reference time point, it maintains the specified power as the power to energize the resistive heating element.

[0124] When the control device determines that the second stop condition is not met at the second reference time point, it changes the power supplied to the resistive heating element from the specified power to the normal power.

[0125] [7] A control device for a ceramic heater module, used to control the ceramic heater module, wherein the ceramic heater module comprises: a ceramic heater having a ceramic substrate with an embedded resistive heating element; and a housing housing the ceramic heater and having an inlet and an outlet for the flow of a liquid medium, the control device for the ceramic heater module comprising:

[0126] A unit for obtaining the inlet temperature and the outlet temperature of the ceramic heater module.

[0127] A unit that determines whether a predetermined stopping condition is met based on the temperature difference between the inlet temperature and the outlet temperature obtained at one or more specific time points after the energization start time point when the resistive heating element is energized with a predetermined power; and

[0128] A unit that stops energizing the resistive heating element when the stopping condition is determined to be met.

[0129] [8] A control device for a ceramic heater module according to any one of [1] to [7], wherein,

[0130] The ceramic heater is a heat exchanger used to heat a liquid medium flowing in a flow path within a device mounted on a vehicle.

[0131] [9] The control device for the ceramic heater module according to [8], wherein,

[0132] The vehicles include electric vehicles, hybrid vehicles, plug-in hybrid vehicles, and fuel cell vehicles.

[0133]

[10] A ceramic heater unit, comprising:

[0134] Control device for ceramic heater module according to any one of [1] to [9]; and

[0135] A ceramic heater module comprising a ceramic heater and a housing, wherein the ceramic heater has a ceramic substrate with an embedded resistive heating element, the housing houses the ceramic heater and has an inlet and an outlet for the flow of a liquid medium.

[0136]

[11] A control program for a ceramic heater module, used to control the ceramic heater module, wherein the ceramic heater module comprises: a ceramic heater having a ceramic substrate with an embedded resistive heating element; and a housing housing the ceramic heater and having an inlet and an outlet for the flow of a liquid medium, the control program of the ceramic heater module causing the following steps to be performed:

[0137] The temperature at the outlet side of the ceramic heater module, i.e., the outlet temperature, is acquired every specified acquisition time.

[0138] The prescribed power is then applied to the resistive heating element.

[0139] The determination of whether a predetermined stop condition is met is based on the temperature difference between the start temperature and the detection temperature, wherein the start temperature is the outlet temperature obtained at the predetermined energization start time, and the detection temperature is the outlet temperature obtained at one or more specific time points after the energization start time; and

[0140] If the stopping condition is determined to be met, the power supply to the resistive heating element is stopped.

[0141]

[12] A control program for a ceramic heater module, used to control the ceramic heater module, wherein the ceramic heater module comprises: a ceramic heater having a ceramic substrate with an embedded resistive heating element; and a housing housing the ceramic heater and having an inlet and an outlet for the flow of a liquid medium, the control program of the ceramic heater module causing the following steps to be performed:

[0142] Every time a predetermined acquisition time has elapsed, the temperature at the inlet side of the ceramic heater module (i.e., the inlet temperature) and the temperature at the outlet side of the ceramic heater module (i.e., the outlet temperature) are acquired.

[0143] The prescribed power is then applied to the resistive heating element.

[0144] The determination of whether the prescribed stopping condition is met is based on the temperature difference between the inlet temperature and the outlet temperature obtained at one or more specific time points after the prescribed power-on start time; and

[0145] If the stopping condition is determined to be met, the power supply to the resistive heating element is stopped.

[0146] Explanation of reference numerals in the attached figures

[0147] 1: Ceramic heater module; 10: Housing; 11: Circular hole; 12: Outlet passage; 20: Ceramic heater; 21: Base; 22: Main body; 23: Flange; 24: First electrode; 25: Second electrode; 30: Control unit; 31: First conductive member; 32: Second conductive member; 33: Power supply; 34: Ammeter; 35: Control device; 351: ECU; 36: Inlet temperature sensor; 37: Outlet temperature sensor; 41: Inlet piping; 42: Outlet piping; 100: Heating device.

Claims

1. A control device of a ceramic heater module for controlling a ceramic heater module, wherein, The ceramic heater module has a ceramic heater having a ceramic base in which a resistance heat generator is embedded, and a case that houses the ceramic heater and has an inlet and an outlet through which a liquid medium flows. The control device of the ceramic heater module has: a unit that acquires a temperature on an outlet side of the ceramic heater module, that is, an outlet temperature; a unit that determines whether a prescribed stop condition is satisfied based on a temperature difference between a start temperature and a detection temperature, the start temperature being the outlet temperature acquired at a power-on start time point at which the resistance heat generator is powered on with a prescribed power, and the detection temperature being the outlet temperature acquired at one or more specific time points after the power-on start time point; and a unit that stops power-on of the resistance heat generator in a case where it is determined that the stop condition is satisfied.

2. The control device of the ceramic heater module according to claim 1, wherein the prescribed power is lower than a normal power with which the ceramic heater is powered on at a time of normal operation of the ceramic heater.

3. The control device of the ceramic heater module according to claim 1, wherein the stop condition includes a first stop condition, the specific time point is a first reference time point at which a prescribed first time elapses from the power-on start time point, the control device determines that the first stop condition is satisfied in a case where the temperature difference is equal to or lower than a prescribed first threshold value.

4. The control device of the ceramic heater module according to claim 3, wherein the prescribed power is lower than a normal power with which the ceramic heater is powered on at a time of normal operation of the ceramic heater, the control device maintains the prescribed power as the power with which the resistance heat generator is powered on until a prescribed reference time point that is a time point after the first reference time point in a case where it is determined that the first stop condition is not satisfied.

5. The control device of the ceramic heater module according to claim 1, wherein the stop condition includes a second stop condition, the specific time point is a plurality of time points that come every time a prescribed small time elapses after the power-on start time point, the control device determines that the second stop condition is satisfied in a case where the temperature difference becomes equal to or higher than a prescribed second threshold value, the control device continues determination of the second stop condition until a second reference time point at which a prescribed second time elapses from the power-on start time point in a case where the second stop condition is not satisfied.

6. The control device of the ceramic heater module according to claim 5, wherein the prescribed power is lower than a normal power with which the ceramic heater is powered on at a time of normal operation of the ceramic heater, the control device maintains the prescribed power as the power with which the resistance heat generator is powered on in a case where it is determined that the second stop condition is not satisfied before the second reference time point, the control device changes the power with which the resistance heat generator is powered on from the prescribed power to the normal power in a case where it is determined that the second stop condition is not satisfied at the second reference time point.

7. A control device of a ceramic heater module for controlling a ceramic heater module, wherein, The ceramic heater module has a ceramic heater having a ceramic base in which a resistance heat generator is embedded, and a case that houses the ceramic heater and has an inlet and an outlet through which a liquid medium flows. The control device of the ceramic heater module has: a unit that acquires a temperature at an inlet side of the ceramic heater module, i.e., an inlet temperature, and a temperature at an outlet side of the ceramic heater module, i.e., an outlet temperature; a unit that determines whether a prescribed stop condition is satisfied based on a temperature difference between the inlet temperature and the outlet temperature acquired at one or more specific time points after a time point at which application of the prescribed electric power to the resistance heat generator is started; a unit that stops application of the electric power to the resistance heat generator when it is determined that the stop condition is satisfied.

8. The control device of the ceramic heater module according to any one of claims 1 to 7, wherein the ceramic heater is a heat exchanger for heating a liquid medium flowing in a flow path in a device mounted on a vehicle.

9. The control device of the ceramic heater module according to claim 8, wherein the vehicle includes an electric vehicle, a hybrid vehicle, a plug-in hybrid vehicle, and a fuel cell vehicle.

10. A ceramic heater unit having: the control device of the ceramic heater module according to any one of claims 1 to 7; and the ceramic heater having a ceramic base in which a resistance heat generator is embedded, and the case that houses the ceramic heater and has an inlet and an outlet through which a liquid medium flows. A ceramic heater module having a ceramic heater and a housing, wherein The ceramic heater module has a ceramic heater having a ceramic base in which a resistance heat generator is embedded, and a case that houses the ceramic heater and has an inlet and an outlet through which a liquid medium flows. The control program of the ceramic heater module causes the following steps to be performed:

11. A computer program product comprising a control program for a ceramic heater module for controlling a ceramic heater module, wherein, the temperature at the outlet side of the ceramic heater module, i.e., an outlet temperature, is acquired each time a prescribed acquisition time elapses; application of the prescribed electric power to the resistance heat generator is started; it is determined whether a prescribed stop condition is satisfied based on a temperature difference between a start temperature and a detection temperature, wherein the start temperature is the outlet temperature acquired at a time point at which application of the prescribed electric power is started, and the detection temperature is the outlet temperature acquired at one or more specific time points after the time point at which application of the electric power is started; and application of the electric power to the resistance heat generator is stopped when it is determined that the stop condition is satisfied. The ceramic heater module has a ceramic heater having a ceramic base in which a resistance heat generator is embedded, and a case that houses the ceramic heater and has an inlet and an outlet through which a liquid medium flows. The control program of the ceramic heater module causes the following steps to be performed:

12. A computer program product comprising a control program for a ceramic heater module for controlling a ceramic heater module, wherein the temperature at the inlet side of the ceramic heater module, i.e., an inlet temperature, and the temperature at the outlet side of the ceramic heater module, i.e., an outlet temperature, are acquired each time a prescribed acquisition time elapses; application of the prescribed electric power to the resistance heat generator is started; it is determined whether a prescribed stop condition is satisfied based on a temperature difference between a start temperature and a detection temperature, wherein the start temperature is the outlet temperature acquired at a time point at which application of the prescribed electric power is started, and the detection temperature is the outlet temperature acquired at one or more specific time points after the time point at which application of the electric power is started; and application of the electric power to the resistance heat generator is stopped when it is determined that the stop condition is satisfied. determining whether a prescribed stop condition is satisfied, based on temperature differences between the inlet temperature and the outlet temperature, which are respectively obtained at one or more specific time points after a prescribed power-on start time point of the electric power; and stopping the power-on to the electric resistance heat generating body, in a case where it is determined that the stop condition is satisfied.

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