JP2015020605A - Vehicle heater - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a highly reliable vehicle heater which achieves low cost and is excellent in quick heating ability and temperature detection stability.SOLUTION: A vehicle heater includes: a heater (2) having a ceramic cylinder (24) including a heat generation pattern (32) which generates heat by energization and a sensor pattern (34) which detects a temperature by energization; and a housing (4) which forms a passage (6) of a heat medium between itself and the heater. The heater includes a bottomed metal cylinder (26) into which the ceramic cylinder is inserted.

Description

  The present invention relates to a vehicle heating device.

  For example, Patent Document 1 discloses a technique in which a temperature detection thermistor material and a heating resistor are baked on the surface of a ceramic inner casing of a thermostatic chamber.

Japanese Patent Publication No.46-18705

  By the way, the conventional vehicle heating device forms a flow path through which a heat medium flows between a heater in which a filler such as magnesium oxide is press-filled in a metal tube and a heating wire such as a nichrome wire is enclosed. A case. A temperature sensor for detecting the temperature of the heater is inserted from the outside of the case and is brought into contact with the heater. Since the temperature sensor is a separate member from the heater, a sealing mechanism for waterproofing the temperature sensor from the flow path is required. In addition, a mechanism for pressing the temperature sensor against the heater is necessary so that the vibration of the case is not transmitted to the temperature sensor and separated from the heater.

  On the other hand, since the heater of the above-mentioned patent document 1 can integrally form a heat generating part and a sensor part in a ceramic material, the above-mentioned sealing mechanism and pressing mechanism become unnecessary, and the number of parts and assembly man-hours are conventionally required. A low-cost heating device that achieves a significant reduction can be realized. Moreover, it is known that ceramic is excellent in thermal conductivity, and it is possible to provide a heating device having higher rapid thermal performance than before. Moreover, since it is not temperature detection by the press contact mentioned above, stability of temperature detection is securable.

However, since the above-mentioned Patent Document 1 discloses a ceramic heater used in a constant temperature bath and assumes a case where the temperature of a relatively low temperature heat medium is maintained, a heating device mounted on a vehicle is exceptionally special. Careful consideration has not been made.
Specifically, the vehicle heating device is mounted on a vehicle such as a hybrid vehicle or an electric vehicle, for example, and quickly supplies heat to the refrigerant circulating in the refrigeration circuit of the vehicle air conditioner to a high temperature (about 100 ° C.).

  In the case of a hybrid vehicle, the heating device is used as an auxiliary heat source for supplying heat to the refrigerant so as to compensate for the waste heat that the engine lacks. Specifically, a coolant (heat medium) such as ethylene glycol that circulates in the coolant circuit cools the engine and then flows into the flow path, and is required to have a heating performance of, for example, about 3 kW in order to be further heated by the heater. . The heat of the coolant heated by the engine and the heating device is used to heat the refrigerant circulating in the refrigeration circuit provided in the vehicle air conditioner, and the vehicle interior air is cooled and heated by the heated refrigerant.

Further, in order to use the above-described ceramic heater for high-temperature heating, a new measure is required for the point that the ceramic has a so-called thermal shock breakdown characteristic that is likely to crack due to abrupt temperature change or uneven temperature distribution. .
In the unlikely event that the ceramic breaks, the fragments may enter the coolant circuit together with the coolant flowing through the flow path of the heating device, which may interfere with the heat exchange system such as engine cooling. Therefore, the above-mentioned prior art does not give special consideration to the thermal shock destruction characteristics of ceramics and the influence on the heat exchange system in which the heating device is used, and still remains a problem in terms of improving the reliability as a vehicle air conditioner. Was left.

  The present invention has been made in view of such problems, and an object of the present invention is to provide a vehicle heating device that is excellent in low cost, rapid thermal performance, temperature detection stability, and high reliability. It is in.

In order to achieve the above object, a vehicle heating apparatus according to the present invention includes a heater having a ceramic cylinder including a heat generation pattern that generates heat by energization and a sensor pattern that detects temperature by energization, and a heat medium between the heaters. The heater is provided with a bottomed metal cylinder into which a ceramic cylinder is inserted.
Preferably, in the heater, a filling layer having thermal conductivity is interposed between the metal cylinder and the ceramic cylinder.

Preferably, the heater has a hollow inside of the ceramic cylinder.
As another preferred embodiment, the heater is formed by filling a ceramic cylinder with a filler having thermal conductivity.
Preferably, the heater has a terminal portion to which the heat generation pattern and the sensor pattern are electrically connected at one end thereof, and the sensor pattern is positioned closer to the terminal portion than the heat generation pattern in the ceramic cylinder.

  According to the vehicle heating device of the present invention, the heater includes a bottomed metal cylinder into which the ceramic cylinder is inserted, so that heat conduction from the heat generation pattern of the ceramic cylinder to the metal cylinder is continuous. Done. Thereby, since the metal generally has a higher thermal conductivity than the ceramic, it is possible to suppress the cracking of the ceramic cylinder due to a rapid temperature change or uneven temperature distribution, that is, the thermal shock breakdown characteristics of the ceramic cylinder.

  Even if the ceramic cylinder breaks, the fragments remain in the metal cylinder and are prevented from mixing into the flow path of the heat medium and thus into the circulation circuit of the heat medium. Harm to the system is prevented. Therefore, it is possible to provide a highly reliable vehicle heating device while using a ceramic heater having low cost, rapid thermal performance, and temperature detection stability.

In addition, the heater can promote heat conduction from the heat generation pattern of the ceramic cylinder to the metal cylinder by interposing a filler layer having thermal conductivity between the metal cylinder and the ceramic cylinder. Therefore, the thermal shock destruction characteristics of the ceramic cylinder can be more effectively suppressed, and the reliability of the vehicle heating device can be further improved.
In addition, since the inside of the ceramic cylinder is hollow, the heater generally has a low thermal conductivity, so that the temperature difference between the heat generation pattern of the ceramic cylinder and the inside thereof can be suppressed. Therefore, it is possible to more effectively suppress the cracking of the ceramic cylinder due to a sudden temperature change or uneven temperature distribution, and consequently the thermal shock fracture characteristics of the ceramic cylinder, and further increase the reliability of the vehicle heating device. Can do.

  On the other hand, since the heater is formed by filling the inside of the ceramic cylinder with a filler having thermal conductivity, heat conduction from the heating pattern of the ceramic cylinder to the inside filler is continuously performed. Moreover, the thermal shock fracture characteristics of the ceramic cylinder can be further suppressed. Therefore, the thermal shock destruction characteristics of the ceramic cylinder can be more effectively suppressed, and the reliability of the vehicle heating device can be further improved.

  Further, the sensor pattern is positioned closer to the terminal portion than the heat generation pattern in the ceramic cylinder. As a result, in the sensor pattern, temperature detection can be performed while minimizing the influence of heat generation by the heat generation pattern, and a temperature change can be transmitted to the terminal portion side as quickly as possible. Therefore, the reliability of the vehicle heating device can be further increased.

It is a longitudinal cross-sectional view of the heating apparatus which concerns on one Embodiment of this invention. It is a longitudinal cross-sectional view of the heater of FIG. FIG. 3 is a perspective view of the ceramic tube of FIG. 2. It is a figure explaining the electricity supply control performed with respect to the heat_generation | fever pattern of FIG.

Hereinafter, an embodiment according to the heating device of the present invention will be described based on the drawings.
As shown in FIG. 1, the heating device 1 includes two heaters 2 and a case (housing) 4 in which the heaters 2 are accommodated.
The case 4 is formed of, for example, one or a plurality of cast bodies of aluminum alloy, and clearances are secured between the heaters 2 and between the heaters 2 and the inner surface 4a of the case 4. This clearance is used as a flow path 6 through which a cooling liquid described later flows.

  Further, O-rings 8 are mounted in the vicinity of both ends of each heater 2. The inner surface 4 a of the case 4 and the support wall 10 projecting from the case 4 are respectively provided with recesses 12 at corresponding positions of the O-ring 8. A part of each O-ring 8 is positioned in these recesses 12, whereby each heater 2 is supported at both ends in the case 4. An annular insulating member 18 disposed so as to surround the lead wire 14 is interposed between the terminal portion 16 from which the lead wire 14 of each heater 2 is drawn and the inner surface 4 a of the case 4.

In this way, the inside and outside of the flow path 6 are hermetically sealed by the O-rings 8 and the transmission of vibrations from the case 4 to the heaters 2 is suppressed. Electrical insulation is provided. Further, an inlet pipe 20 and an outlet pipe 22 communicating with the flow path 6 are projected from the outer surface 4 b of the case 4.
The heating device 1 configured as described above is mounted on a vehicle such as a hybrid vehicle or an electric vehicle, and supplies heat to a refrigerant circulating in the refrigeration circuit of the vehicle air conditioner.

  For example, in the case of a hybrid vehicle, it is used as an auxiliary heat source for supplying heat to the refrigerant so as to compensate for the waste heat that the engine lacks. Specifically, a coolant (heat medium) such as ethylene glycol circulating in a coolant circuit (not shown) cools the engine and then flows into the flow path 6 through the inlet pipe 20 and is further heated by the heater 2. The heat of the coolant heated by the engine and the heating device 1 is used to heat the refrigerant circulating in the refrigeration circuit provided in the vehicle air conditioner.

The vehicle interior air is cooled and heated by the heated refrigerant. The coolant cooled by heating the refrigerant flows out from the flow path 6 through the outlet pipe 22 and returns to the coolant circuit, thereby cooling the engine again. The heating device 1 is used as an alternative heat source for supplying heat to the refrigerant in place of an engine that does not exist in the case of an electric vehicle.
As shown in FIG. 2, the heater 2 is a ceramic heater that generates heat when energized, and is formed of a cylindrical ceramic tube (ceramic cylinder) 24 and a bottomed cylindrical shape, for example, stainless steel into which the ceramic tube 24 is inserted. The metal pipe (metal cylinder) 26 is provided.

In the present embodiment, a hollow portion 28 is formed inside the ceramic tube 24. Further, between the metal tube 26 and the ceramic tube 24, a filling layer 30 such as magnesium oxide having at least high thermal conductivity, preferably electrical insulation and heat resistance is interposed.
The terminal portion 16 described above is formed in one end opening of the metal tube 26, and the terminal portion 16 is formed by casting and molding silicon or glass. The aforementioned lead wire 14 is drawn out from the terminal portion 16, and the lead wire 14 is electrically connected to an external power supply device (not shown).

  As shown in FIG. 3, the ceramic tube 24 includes a heat generation pattern 32 that generates heat by energization and a sensor pattern 34 that detects temperature by energization, both of which are electrically connected to the power supply device via the lead wires 14. Connected to each other to constitute an energization circuit (not shown). The sensor pattern 34 is a resistance thermometer that detects a change in electrical resistance due to energization as a temperature change, and is positioned closer to the terminal portion 16 than the heat generation pattern 32 in the ceramic tube 24. Note that the patterns 32 and 34 may be printed on the surface of the ceramic tube 24.

The two lead wires 14 drawn from the outer end of the sensor pattern 34 are electrically connected to an inverter (not shown). The inverter performs energization control for turning on / off the energization of the heat generation pattern 32 according to the temperature change detected by the sensor pattern 34 via the power supply device and the energization circuit described above.
As shown in FIG. 4, in this energization control, first, it is determined whether or not the temperature T detected by the sensor pattern 34 is equal to or higher than a predetermined first threshold value TS1 when the energization to the heat generation pattern 32 is on. To do.

When the relational expression of T ≧ TS1 is satisfied, it is determined that the temperature of the heater 2 has abnormally increased, and the energization of the heat generation pattern 32 is turned off to enter the energization standby state (wait state).
Next, it is determined whether or not the temperature T detected by the sensor pattern 34 is equal to or higher than a predetermined second threshold value TS2 in a state where the energization of the heat generation pattern 32 is off. The second threshold value TS2 is a value smaller than the first threshold value TS1. When the relational expression of T ≦ TS2 is satisfied, it is determined that the temperature of the heater 2 is in an appropriate range, and the energization of the heat generation pattern 32 is turned on to return to the energization return state.

As described above, when a predetermined amount of coolant is present in the flow path 6, the temperature of the coolant is controlled within an appropriate range of TS 2 or more and TS 2 or less. It will not rise.
On the other hand, in spite of the energization standby state in which the energization of the heat generation pattern 32 is turned off, the temperature T detected by the sensor pattern 34 may further increase rather than decrease to the second threshold value TS2. In this case, it is determined whether or not the temperature T is equal to or higher than a predetermined third threshold value TS3 that is higher than the first threshold value TS1.

When the relational expression of T ≧ TS3 is established, there is no cooling liquid in the flow path 6 due to the non-supply state of the cooling liquid to the cooling liquid circuit or the leakage of the cooling liquid from the cooling liquid circuit or the like. Then, it is determined that the cooling liquid in the flow path 6 is in a so-called empty state where the amount of the cooling liquid is less than a specified amount.
In this case, the temperature of the heater 2 itself is abnormally increased, and there is a possibility that the heating device 1 may emit smoke. In this abnormality process, the energization of the heat generation pattern 32 is continuously turned off to set the energization completely stopped state (sleep state), and subsequent energization return is not automatically performed.

  As described above, in the present embodiment, the heater 2 includes the bottomed metal tube 26 into which the ceramic tube 24 is inserted, so that heat conduction from the heat generation pattern 32 of the ceramic tube 24 to the metal tube 26 is continuous. Done. As a result, since metal generally has a higher thermal conductivity than ceramic, cracks in the ceramic tube 24 due to sudden temperature changes and uneven temperature distribution, that is, thermal shock breakdown characteristics of the ceramic tube 24 can be suppressed.

  Even if the ceramic tube 24 is cracked, the fragments remain in the metal tube 26 and are prevented from entering the coolant flow path 6 and thus into the coolant circuit. Harm to the system (heat exchange system) is prevented. Therefore, it is possible to provide a highly reliable heating device 1 while using a ceramic heater having low cost, rapid thermal performance, and temperature detection stability.

Further, the heater 2 promotes heat conduction from the heat generation pattern 32 of the ceramic tube 24 to the metal tube 26 by interposing a filler layer 30 having thermal conductivity between the metal tube 26 and the ceramic tube 24. Can do. Therefore, the thermal shock destruction characteristics of the ceramic tube 24 can be further effectively suppressed, and the reliability of the heating device 1 can be further improved.
In addition, since the heater 2 has a hollow portion 28 in which the inside of the ceramic tube 24 is hollow, air generally has a low thermal conductivity, so that a temperature difference between the heat generation pattern 32 of the ceramic tube 24 and the inside thereof is suppressed. be able to. Therefore, the thermal shock destruction characteristics of the ceramic tube 24 can be further effectively suppressed, and the reliability of the vehicle heating apparatus 1 can be further enhanced.

  Further, the sensor pattern 34 is positioned closer to the terminal portion 16 than the heat generation pattern 32 in the ceramic tube 24. As a result, the sensor pattern 34 can perform temperature detection while minimizing the influence of heat generation by the heat generation pattern 32, and can change the temperature to the inverter connected to the terminal portion 16 via the lead wire 14 as quickly as possible. It can be transmitted. Therefore, the reliability of the heating device 1 can be further increased.

The present invention is not limited to the heating device 1 of the above embodiment, and various modifications can be made.
For example, in the above-described embodiment, the hollow portion 28 is formed in the heater 2, but the present invention is not limited to this. A heater may be formed by filling (magnesium oxide or the like). Even in this case, since the heat conduction from the heat generation pattern 32 of the ceramic tube 24 to the inner filler is continuously performed, the thermal shock breakdown characteristics of the ceramic tube 24 can be effectively suppressed. The reliability of the heating device 1 can be further increased.

Further, in the above embodiment, the case where the heater 2 has the filling layer 30 has been described. However, even if the ceramic tube 24 is not inserted into the metal tube 26 without the filling layer 30, the essential feature of the present invention. A sufficient effect can be obtained.
Moreover, although the heating apparatus 1 which accommodates the two heaters 2 was demonstrated in the said embodiment, this invention is applicable even when it is a case where one heater is provided or three or more are provided. .

The coolant flowing through the flow path 6 is not limited to ethylene glycol and various heat media can be applied.
In addition, the vehicle heating device of the present invention can be used not only as a vehicle air conditioner for hybrid vehicles and electric vehicles, but also as a vehicle heat source for other uses of other types of vehicles. is there.

DESCRIPTION OF SYMBOLS 1 Heating device for vehicles 2 Heater 4 Case 6 Flow path 16 Terminal part 24 Ceramic tube (ceramic cylinder)
26 Metal tube (metal cylinder)
30 Packing layer 32 Heat generation pattern 34 Sensor pattern

Claims (5)

A heater having a ceramic cylinder including a heat generation pattern that generates heat by energization and a sensor pattern that detects temperature by energization;
A housing that forms a flow path of a heat medium between the heater and
The heater includes a bottomed metal cylinder into which the ceramic cylinder is inserted.   The vehicle heater according to claim 1, wherein the heater has a packed layer having thermal conductivity between the metal cylinder and the ceramic cylinder.   The vehicle heater according to claim 1, wherein the heater has a hollow inside of the ceramic cylinder.   The vehicle heater according to claim 1 or 2, wherein the heater is formed by filling a thermal conductive filler inside the ceramic cylinder. The heater has, at one end thereof, a terminal portion to which the heat generation pattern and the sensor pattern are electrically connected,
5. The vehicle heating device according to claim 1, wherein the sensor pattern is positioned closer to the terminal portion than the heat generation pattern in the ceramic cylinder. 6.

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