JP2013193513A - Electric heater - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable suppression of an inrush current while increasing a heating value of an entire electric heater and prevent other components from causing heat damage.SOLUTION: An electric heater 1 is configured by arranging a plurality of heat generating units 11 to 16 having heat generating bodies each generating heat by an electrical current passing therethrough. The electric heater 1 has an electric circuit connecting the heat generating unit 11 with the heat generating unit 12 to each other in parallel, and a heating value of the heat generating unit 11 close to an end of the electric heater 1 is set to be smaller than a heating value of the other heat generating unit 12.

Description

  The present invention relates to an electric heater used when, for example, air is heated.

  2. Description of the Related Art Conventionally, an electric heater using a PTC element that generates heat when an electric current flows is known. This electric heater may be housed in, for example, a casing of a vehicle air conditioner and used as a heater for air conditioning air (see, for example, Patent Documents 1 and 2).

JP 2001-1751 A JP 2009-90764 A

  By the way, in an electric vehicle, for example, engine cooling water cannot be used as a heating heat source. Therefore, it is necessary to secure heating capacity by increasing the amount of heat generated by the electric heater.

  In order to increase the amount of heat generated by the entire electric heater, it is conceivable to provide a plurality of heating elements made of PTC elements and select a heating element having a small electrical resistance value.

  However, when a heating element having a small electrical resistance value is used, the current immediately after the current starts flowing (inrush current) increases. When the inrush current is large, a circuit design corresponding to the large current is required. Therefore, there is a demand for making the inrush current as small as possible.

  As a method for increasing the amount of heat generated by each heating element, there is a method for selecting an element having a high Curie temperature. However, when the calorific value is increased, the portion of the electric heater that is close to the casing becomes hot, and there is a concern about heat damage to the casing.

  The present invention has been made in view of the above points, and the object of the present invention is to suppress inrush current while increasing the amount of heat generated by the entire electric heater and to other members and the like. It is to prevent heat damage.

  In order to achieve the above object, in the present invention, a heating unit having a heating element is connected in parallel to form an electric circuit, and in one electric circuit, heat generation of the heating unit that is relatively close to other members. The amount was made smaller.

A first invention is an electric heater constituted by arranging a plurality of heat generating units having a heat generating element that generates heat by flowing an electric current,
Having an electric circuit in which two or more heat generating units are connected in parallel;
The heat generation amount of the heat generation unit near the end of the electric heater is set to be smaller than the heat generation amounts of other heat generation units.

  According to this configuration, the combined resistance value of the plurality of heat generating units becomes the resistance value of the electric circuit, and the inrush current is determined by this resistance value, so that the inrush current of the electric heater can be suppressed. become. At this time, by making the electric resistance value of the heating element of the heating unit near the end of the electric heater higher than the electric resistance value of the heating element of the other unit, the amount of heat generated near the end of the electric heater can be reduced. It is suppressed. As a result, for example, when an electric heater is attached to the casing of the air conditioner, it is possible to prevent thermal damage to the casing.

  In the above case, the electrical resistance value of the heating element of the other heating unit constituting the electrical circuit is smaller than the electrical resistance value of the heating element of the heating unit near the end of the electric heater. The unit generates a large amount of heat, which makes it possible to secure a sufficient amount of heat when viewed as an entire electric heater.

According to a second invention, in the first invention,
The heating unit has a plurality of heating elements,
A heat transfer fin is disposed between the heat generating units.

  According to this configuration, the heat generation amount of each heat generating unit is sufficiently ensured by the plurality of heat generating elements, and the heat generated by each heat generating unit is efficiently transmitted to air or the like through the fins.

According to a third invention, in the first or second invention,
The electrical resistance value of the heating element of the heating unit near the end of the electric heater is larger than the electrical resistance value of the heating elements of the other heating units.

  According to this configuration, the amount of heat generated by each unit can be changed with a simple configuration in which the electric resistance value of the heating element is changed.

  According to the first invention, two or more heating units are connected in parallel to form an electric circuit, and the heating value of the heating unit near the end of the electric heater is set to be higher than the heating values of the other heating units. Since it is set small, the inrush current can be suppressed while increasing the heat generation amount of the entire electric heater, and the temperature rise at the end of the electric heater is suppressed so as not to cause heat damage to other members. be able to.

  According to the second aspect, since the heat transfer fins are disposed between the heat generating units having a plurality of heat generating elements, the generated heat can be efficiently transmitted to the object to be heated.

  According to the third aspect of the present invention, it is possible to easily provide a difference in the amount of heat generated by the heat generating unit with a simple configuration in which the electric resistance value of the heat generating element is changed.

It is a perspective view of an electric heater. It is an exploded view of an electric heater. It is an exploded view of a heat generating unit and a fin. It is a figure which shows the state by which the heat generating body was hold | maintained at the holder. It is a circuit diagram of an electric heater.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. It should be noted that the following description of the preferred embodiment is merely illustrative in nature, and is not intended to limit the present invention, its application, or its use.

  FIG. 1 is a perspective view of an electric heater 1 according to an embodiment of the present invention. The electric heater 1 includes a core 10, an electrode holder 30, and first and second protective members 41 and 42, for example, a casing A (shown in phantom lines in FIG. 1) of a vehicle air conditioner. It is housed inside and functions as a heater that heats air for air conditioning. The casing A is made of, for example, resin. In addition to the electric heater 1, the casing A accommodates an evaporator as a heat exchanger for cooling, an air mix damper, and the like (not shown). The evaporator is arranged upstream of the electric heater 1 in the air flow direction, and the mixing ratio of the air cooled by passing through the evaporator and the air heated by passing through the electric heater 1 is an air mix. It is changed by a damper to generate conditioned air at a desired temperature.

  As shown in FIG. 2, the core 10 includes first to sixth heat generating units 11 to 16, a plurality of fins 25, 25,... And a pair of end plates 26 and 26. The first to sixth heat generating units 11 to 16 have a long and narrow box shape, and are arranged at intervals in a predetermined direction. The first heat generating unit 11 is located at one end in the width direction of the electric heater 1, and the sixth heat generating unit 16 is located at the other end in the width direction of the electric heater 1. The second to fifth heat generating units 12 to 15 are arranged in order from the first heat generating unit 11 side to the sixth heat generating unit 16 side between the first heat generating unit 11 and the sixth heat generating unit 16. Between the adjacent units of the first to sixth heating units 11 to 16, two fins 25 are arranged so as to be aligned in the width direction of the electric heater 1. Each fin 25 is accommodated in a cylindrical member 28.

  Since the basic structure of the first to sixth heat generating units 11 to 16 is the same, the structure of the first heat generating unit 11 will be described.

  As shown in FIG. 3, the first heating unit 11 includes a number of heating elements 17, 17,..., A holder 19 that holds the heating elements 17, an anode-side electrode 20, a cathode-side electrode 21, and a case 22. It has. The heating element 17 is composed of a PTC element that generates heat when an electric current flows. In the present embodiment, 13 heating elements 17 are provided, but the number of heating elements 17 is not limited to this.

  As shown in FIG. 4, the holder 19 is made of an insulating resin material and has an elongated plate shape as a whole. The holder 19 is formed with a through hole 19a into which the heating element 17 is inserted so as to penetrate in the thickness direction. The same number of through-holes 19 a as the number of heating elements 17 are formed, and are arranged at intervals in the longitudinal direction of the holder 19. The heating element 17 is held by the holder 19 while being inserted into the through hole 19a.

  The anode electrode 20 is made of a conductive metal plate and is formed so as to extend along the longitudinal direction of the holder 19. The anode-side electrode 20 is disposed so as to cover one side surface of the holder 19, and in this state, the anode-side electrode 20 is in contact with and electrically connected to each heating element 17 held by the holder 19. A connecting portion 20 a is formed at one end portion of the anode side electrode 20 in the longitudinal direction so as to protrude in the longitudinal direction of the anode side electrode 20. The connecting portion 20a is offset to one side in the thickness direction of the electric heater 1 (external air flow direction).

  An insulating film 29 is disposed on the side surface of the anode side electrode 20 opposite to the holder 19. The film 29 insulates the anode side electrode 20 from the case 22.

  The cathode side electrode 21 is also made of a conductive metal plate and extends in the same manner as the anode side electrode 20. The cathode side electrode 21 is disposed so as to cover the other side surface of the holder 19 opposite to the anode side electrode 20, and in this state, the cathode side electrode 21 is in contact with and electrically connected to each heating element 17. A connecting portion 21 a is formed at one end of the cathode side electrode 21 in the longitudinal direction so as to protrude in the same direction as the connecting portion 20 a of the anode side electrode 20. The connecting portion 21a is displaced to the other side in the thickness direction of the electric heater 1, that is, the side opposite to the connecting portion 20a of the anode side electrode 20.

  An insulating film 29 is also provided on the side of the cathode side electrode 21 opposite to the holder 19, and the film 29 insulates the cathode side electrode 21 from the case 22.

  The case 22 is made of a metal material having high thermal conductivity and has a long and narrow box shape. An opening 22 a is formed on the end surface of the case 22 in the longitudinal direction. The case 22 accommodates the cathode side electrode 21, the holder 19 holding the heating element 17, the anode side electrode 20, and the film 29 from the opening 22a.

  The first to sixth heat generating units 11 to 16 are electrically insulated.

  The units 11 and 12 are configured by selecting the heating element 17 so that the electrical resistance value of the heating element 17 of the first heating unit 11 is larger than the electrical resistance value of the heating element 17 of the second heating unit 12. Yes. Thereby, the heat generation amount of the first heat generation unit 11 near the end of the electric heater 1 is set smaller than the heat generation amount of the second heat generation unit (other heat generation unit) 12.

  Further, both units 15 and 16 are configured by selecting the heating element 17 so that the electrical resistance value of the heating element 17 of the sixth heating unit 16 is larger than the electrical resistance value of the heating element 17 of the fifth heating unit 15. doing. Thereby, the heat generation amount of the sixth heat generation unit 16 close to the end of the electric heater 1 is set smaller than the heat generation amount of the fifth heat generation unit (other heat generation unit) 15.

  As shown in FIG. 1, fins 25 and 25 are provided at both outer ends of the core 10 in the direction in which the first to sixth heat generating units 11 to 16 are arranged. The end plates 26 and 26 are provided so as to cover the outer sides of the fins 25 and 25 at the outer end.

  The electrode holder 30 is made of an insulating resin material and extends across both ends of the first to sixth heat generating units 11 to 16 in the arrangement direction. As shown in FIG. 2, the electrode holder 30 is provided with first to third anode side jumpers 31 to 33 and a cathode side jumper 34 in an insulated state.

  The cathode side jumper 34 is connected to the connection portion 21a of the cathode side electrode 21 of the first to sixth heat generating units 11-16. A cathode wiring 34 a is connected to the cathode side jumper 34. The cathode wiring 34a is connected to a control device (not shown).

  The first anode side jumper 31 is connected to the connection part 20 a of the anode side electrode 20 of the first heat generation unit 11 and the connection part 20 a of the anode side electrode 20 of the second heat generation unit 12. Thereby, as shown in FIG. 5, one electric circuit C1 in which the first heat generating unit 11 and the second heat generating unit 12 are connected in parallel is configured.

  The second anode side jumper 32 is connected to the connecting portion 20 a of the anode side electrode 20 of the third heat generating unit 13 and the connecting portion 20 a of the anode side electrode 20 of the fourth heat generating unit 14. Thereby, one electric circuit C2 in which the third heat generating unit 13 and the fourth heat generating unit 14 are connected in parallel is configured.

  The third anode side jumper 33 is connected to the connection portion 20 a of the anode side electrode 20 of the fifth heat generation unit 15 and the connection portion 20 a of the anode side electrode 20 of the sixth heat generation unit 16. Thereby, one electric circuit C3 in which the fifth heat generating unit 15 and the sixth heat generating unit 16 are connected in parallel is configured.

  Anode wirings 31 a to 33 a are connected to the first to third anode side jumpers 31 to 33. These anode wirings 31a to 33a are also connected to the control device.

  The 1st protection member 41 is comprised by the resin material etc. which have insulation, and is arrange | positioned at the edge part by the side of the electrode holder 30 of the electric heater 1. The first protective member 41 covers the first to third anode side jumpers 31 to 33 and the cathode side jumper 34.

  The second protection member 42 is disposed at the end of the electric heater 1 opposite to the electrode holder 30 and is formed so as to cover the end face of the electric heater 1.

  The first protective member 41 or the electrode holder 30 of the electric heater 1 is attached to the casing A of the air conditioner using screws or the like.

  The control device is configured to allow current to flow individually to the electric circuits C1 to C3. For example, when strong heating is required, current is supplied to all of the electric circuits C1 to C3, and when weak heating is sufficient, current is supplied to one or two of the electric circuits C1 to C3. .

  When a current is passed through the electric circuit C1, a current flows through the heating element 17 of the first heat generating unit 11 to generate heat. Similarly, the heating element 17 of the second heating unit 12 also generates heat. At this time, since the first heat generating unit 11 and the second heat generating unit 12 are connected in parallel, the combined resistance value of the first heat generating unit 11 and the second heat generating unit 12 becomes the resistance value of the electric circuit C1. Thereby, inrush current can be suppressed.

  Since the electrical resistance value of the heating element 17 of the first heating unit 11 is larger than the electrical resistance value of the heating element 17 of the second heating unit 12, the heating value of the first heating unit 11 is larger than the heating value of the second heating unit 12. Becomes smaller. The first heat generating unit 11 is located at the end of the electric heater 1 and is close to the inner surface of the casing A. However, heat damage to the casing A can be prevented by reducing the heat generation amount as described above.

  On the other hand, by making the electrical resistance value of the heating element 17 of the second heating unit 12 smaller than the electrical resistance value of the heating element 17 of the first heating unit 11, the amount of heat generated by the second heating unit 12 becomes large. Thereby, it becomes possible to secure a sufficient amount of heat generation when viewed as the electric heater 1 as a whole.

  Even when an electric current is passed through the electric circuit C3, it is possible to secure a sufficient amount of heat generation when viewed as the electric heater 1 as a whole while preventing heat damage to the casing A.

  As described above, according to the electric heater 1 according to this embodiment, the first heat generating unit 11 and the second heat generating unit 12 are connected in parallel to form the electric circuit C1, and the electric heater 1 Since the heat generation amount of the first heat generation unit 11 close to the end is set smaller than the heat generation amount of the second heat generation unit 12, the inrush current can be suppressed while increasing the heat generation amount of the electric heater 1 as a whole. It is possible to prevent the thermal damage of the casing A by suppressing the temperature rise at the end of the heater 1. The same applies to the electric circuit C3.

  Moreover, since the heat transfer fins 25 are disposed between the first to sixth heat generating units 11 to 16, the generated heat can be efficiently transmitted to the air-conditioning air.

  In addition, although the said embodiment demonstrated the case where the electric heater 1 was used for a vehicle air conditioner, it is not restricted to this, For example, it can be used also for a general household air conditioner etc.

  As described above, the electric heater according to the present invention can be used, for example, in a vehicle air conditioner.

DESCRIPTION OF SYMBOLS 1 Electric heater 10 Core 11-16 1st-6th heat generating unit 17 Heating body 19 Holder 20 Anode side electrode 21 Cathode side electrode 25 Fin 26 End plate 30 Electrode holder

Claims (3)

In an electric heater configured by arranging a plurality of heat generating units having a heating element that generates heat by passing an electric current,
Having an electric circuit in which two or more heat generating units are connected in parallel;
An electric heater characterized in that the heat generation amount of the heat generation unit near the end of the electric heater is set smaller than the heat generation amount of other heat generation units. The electric heater according to claim 1,
The heating unit has a plurality of heating elements,
An electric heater characterized in that fins for heat transfer are disposed between the heat generating units. The electric heater according to claim 1 or 2,
An electric heater characterized in that an electric resistance value of a heating element of a heating unit near the end of the electric heater is larger than an electric resistance value of a heating element of another heating unit.

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