EP0204393A2 - Appareil de chauffage électrique - Google Patents

Appareil de chauffage électrique Download PDF

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Publication number
EP0204393A2
EP0204393A2 EP86300809A EP86300809A EP0204393A2 EP 0204393 A2 EP0204393 A2 EP 0204393A2 EP 86300809 A EP86300809 A EP 86300809A EP 86300809 A EP86300809 A EP 86300809A EP 0204393 A2 EP0204393 A2 EP 0204393A2
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EP
European Patent Office
Prior art keywords
holder
heater
heating elements
fan
apertures
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
EP86300809A
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German (de)
English (en)
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EP0204393A3 (fr
Inventor
Kosta Pelonis
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Individual
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Individual
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Filing date
Publication date
Application filed by Individual filed Critical Individual
Publication of EP0204393A2 publication Critical patent/EP0204393A2/fr
Publication of EP0204393A3 publication Critical patent/EP0204393A3/fr
Withdrawn legal-status Critical Current

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    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
    • H05B3/00—Ohmic-resistance heating
    • H05B3/10—Heating elements characterised by the composition or nature of the materials or by the arrangement of the conductor
    • H05B3/12—Heating elements characterised by the composition or nature of the materials or by the arrangement of the conductor characterised by the composition or nature of the conductive material
    • H05B3/14—Heating elements characterised by the composition or nature of the materials or by the arrangement of the conductor characterised by the composition or nature of the conductive material the material being non-metallic
    • H05B3/141—Conductive ceramics, e.g. metal oxides, metal carbides, barium titanate, ferrites, zirconia, vitrous compounds
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F24—HEATING; RANGES; VENTILATING
    • F24H—FLUID HEATERS, e.g. WATER OR AIR HEATERS, HAVING HEAT-GENERATING MEANS, e.g. HEAT PUMPS, IN GENERAL
    • F24H3/00—Air heaters
    • F24H3/02—Air heaters with forced circulation
    • F24H3/04—Air heaters with forced circulation the air being in direct contact with the heating medium, e.g. electric heating element
    • F24H3/0405—Air heaters with forced circulation the air being in direct contact with the heating medium, e.g. electric heating element using electric energy supply, e.g. the heating medium being a resistive element; Heating by direct contact, i.e. with resistive elements, electrodes and fins being bonded together without additional element in-between
    • F24H3/0411—Air heaters with forced circulation the air being in direct contact with the heating medium, e.g. electric heating element using electric energy supply, e.g. the heating medium being a resistive element; Heating by direct contact, i.e. with resistive elements, electrodes and fins being bonded together without additional element in-between for domestic or space-heating systems
    • F24H3/0417—Air heaters with forced circulation the air being in direct contact with the heating medium, e.g. electric heating element using electric energy supply, e.g. the heating medium being a resistive element; Heating by direct contact, i.e. with resistive elements, electrodes and fins being bonded together without additional element in-between for domestic or space-heating systems portable or mobile

Definitions

  • the invention relates to forced-air electric heaters, and more particularly to improvements in the construction of electric heaters incorporating semiconductor heating elements.
  • Electric heaters employing semiconductor heating elements represent a marked improvement over prior resistance-wire type heaters.
  • These new heaters include a heating element which consists of a planar core of semiconductor material formed with a multiplicity of apertures that permit passage of air to draw heat from the core. Opposing faces of the core are coated with electrically conductive coatings that produce a fairly even distribution of current flow in the core when a voltage difference is applied to the coatings.
  • These heaters tend to be more durable than prior resistance-wire type heaters, tend to be more compact for a given heat requirement, and have the additional advantage that very hot air flows can be produced while the temperature of the associated heating element remains below about 200 degrees centigrade, thereby reducing the risk of fire, particularly where there are flammable materials in the heated environment.
  • Such a heater is described in CA-1 190 579.
  • Heaters incorporating semiconductor heating elements of the type described above are still relatively novel, and a number of problems have arisen in the construction of such heaters.
  • a convenient, inexpensive mechanism is required to hold the heating elements.
  • This problem tends to be more critical in the new type heaters than the old resistance-wire type, as the heating element tends to be smaller and air flows from an associated fan must consequently be more tightly constrained to achieve the full benefit of employing such heating elements.
  • considerable care must be taken to simultaneously insure electrical and heat isolation of the heating elements from any associated housing and proper electrical contact with a supply of line voltage.
  • Each heating element includes a generally planar core with a pair of opposing forward and rear core faces, electrically conductive coatings covering each of the opposing faces, and a multiplicity of apertures which permit air flow through the core.
  • the cores are formed of a semiconductor material with a positive resistance-temperature coefficient, the significance of which will be discussed below in connection with a preferred embodiment of the invention.
  • the holder is adapted to direct air flows escaping from the forward fan venturi opening through the cores.
  • the holder comprises air flow receiving means, including a recess formed in a rear face of the holder and positioned at the forward fan venturi opening, which receive substantially all air flow from the forward venturi opening in the recess.
  • a multiplicity of passages in the holder guide air received in the recess through the heating elements.
  • Each passage extends between a forward face and the rear face of the holder, and each passage has a forward opening in the forward face of the holder and a rear opening in the recess, spaced forwardly of the forward fan venturi opening.
  • Each passage is associated with a different one of the heating elements, the associated heating element being positioned intermediate of the forward and rear passage openings, and positioned so that all air flow in the passage is constrained to flow through the core.
  • each of the passages has a minimum cross-sectional area which corresponds substantially to the cross-sectional area of the associated heating element.
  • Each passage is flared rearwardly and radially outwardly from the rear face of the associated heating element to guide air flows smoothly towards the heating element.
  • the recess is similarly flared, radially outwardly and rearwardly, from about the rear passage openings to the rear face of the holder.
  • the flaring which may be either convex or concave result in less turbulent air flows and consequently quieter operation.
  • Electrical connection means are provided which extend into the holder for placing the coatings of each heating element in contact with the source of electric power, and also serve to place the fan in contact with the source of power.
  • Figure 2 illustrates the major components (excepting wiring) of an electric heater 10 embodying the invention which is illustrated generally in Figure 1.
  • the construction, function and assembly of many of the components will be readily apparent, and consequently details of the various components relating specifically to the invention will be provided in order to better highlight the invention.
  • the heater 10 includes a housing constructed of sheet metal.
  • the housing includes a main housing member 12 whose front face has a forward air outlet 14 circumscribed by abutment flanges 16 (only one specifically indicated in fig. 2).
  • the housing also includes a rear housing insert which fits tightly into the back of the main housing member 12 and which is retained to the main housing member 12 by means of screws (not illustrated) threaded through holes 20 (only one specifically indicated) provided in the sidewalls of the main housing member 12.
  • the rear housing insert 18 has a rear air inlet 22 which is normally covered by a removable sheet 24 of appropriate air filtering material, retained by means of brackets 26 (two such brackets being illustrated in the cross-sectional view of fig. 4).
  • the heating function of the electric heater 10 is provided by four disk-shaped heating elements 28, 30, 32, 34.
  • the heating elements are substantially identical, and consequently only the heating element 28 will be described in detail (with components of the heating element 28 better illustrated in the schematic representation of fig. 5).
  • the heating element 28 includes a planar core 40 of semiconductor material having a forward face 42, an opposing rear face 44 and a generally circular peripheral edge 46.
  • the thickness of the core 40 is about 6.4mm, and the diameter of the peripheral edge 46 is about 49mm.
  • Conductive silver coatings 48, 50 are deposited on the forward and rear core faces 42, 44, and serve to produce a distributed current flow between the opposing core faces 42, 44 when a voltage difference is applied to the coatings 48, 50.
  • a multiplicity of apertures 43 extending between the forward and rear core faces 42, 44 permit air flow through the core 40 to draw heat from the core 40 during operation.
  • the relative orientation of the cores is that illustrated in fig. 2, namely, a generally coplanar, spaced-apart relationship.
  • the semiconductor material of the cores is preferrably a mixture of lead titanate and barium titanate, although a variety of other semiconductor materials may be used.
  • the semiconductor material has a relatively high resistance-temperature coefficient, which is normally about 7.65 ohms/°C (as measured between the opposing faces of all cores and considering the cores as parallel resistances).
  • the resistance as measured between the opposing faces of the cores totals about 8 ohms at 165°C and about 161 ohms at 185°C. With a line voltage of 110 v.
  • the cores will have a nominal power consumption of about 1,500 W at an operating temperature of 165°C, and a nominal power consumption of 75 W at an operating temperature of 185°C. It will be readily apparent that the power consumption of the cores drops markedly as the operating temperature of the cores rises. Accordingly, in most circumstances, with no air flow through the cores to draw heat, the cores may be expected to reach an equilibrium temperature below about 200°C.
  • a fan 52 is mounted inside the main housing member 12 intermediate of the rear air inlet 18 and the forward air outlet 14.
  • the fan 52 has a fan casing 54 which defines a fan venturi 56.
  • the fan venturi has a forward venturi opening 58, a rear venturi opening 60 and a central longitudinal axis 62.
  • the fan 52 has a central hub 64 mounted in the fan venturi 56 in general alignment with the venturi axis 62 by means of a spider 66 which has four legs 68 (only one specifically indicated) connecting the hub 64 to the fan casing 54.
  • the hub 64 contains an electric motor (not illustrated) and a fan blade assembly 70 which can be rotated by the motor to produce an air flow forwardly through the fan venturi 56. Power to operate the motor is conducted through one of the legs of the spider 66, in a manner which will not be described.
  • a suitable fan is sold by Rotron Inc. of Woodstock, New York, U.S.A. under the trade mark Muffin.
  • the heater 10 also includes a heating element holder which holds the heating elements 28, 30, 32, 34 in the generally coplanar, spaced-apart relationship referred to above.
  • the heating element holder also orients the cores of the heating elements generally perpendicular to the longitudinal axis 62 of the fan venturi 56, spaced about 25mm forwardly of the forward venturi opening 58 with each'rear core face facing towards the forward venturi opening 58.
  • the holder has a two-piece separable construction involving a forward holder member 72 and a rear holder member 74, each of which is formed of a ceramic material.
  • ceramic material as used in this specification is intended to denote a clay-like material such as fired greenware, porcelain or any other material conventionally referred to as a ceramic material that can be molded in an initial condition and then fired to produce a hard durable product and that has both heat-insulating and electric- insulating properties. Such ceramic materials are inexpensive and easily molded into the shapes required. It will be appreciated, however, that the resultant product tends to be very brittle.
  • the forward holder member 72 defines a forward face 76 of the holder and has an opposing inner face 78.
  • the rear holder member 74 defines a rear face 80 of the holder and has an opposing inner face 82 which is positioned adjacent the inner face 78 when the heating element holder is fully assembled.
  • the inner holder member faces 78, 82 are contoured to define pockets (two specifically indicated by reference numerals 84, 86 in the cross-sectional view of fig. 4) in which the heating elements are retained.
  • the contouring is effected by providing triangular projections 88, 90 (only two specifically indicated in fig. 3 where the contouring is best shown) and central circular projections 92, 94, best illustrated in the view of fig. 3 where the holder member 72, 76 are shown separated.
  • the pockets closely receive the heating elements, gripping the opposing faces of each heater element core.
  • the heating element holder also has four passages, one associated with a different one of the four heating elements, which direct air flows through the heating elements.
  • Each passage extends between the forward and rear holder faces 76, 80, and has a forward passage opening (not specifically indicated) in the forward holder face 76 and a rear passage opening (not specifically indicated) in the rear holder face 80, more specifically, in a recess formed in the rear holder face 80 and described more fully below.
  • Two such passages 96, 98 are specifically indicated in the cross-sectional view of fig. 4. It will be apparent from fig.
  • each of the passages 96, 98 intersects the pocket in which the associated heating element 28, 32, respectively, is contained, and that each of the passages 96, 98 has a minimum cross-sectional area perpendicular to the venturi axis 62 which is substantially the same as the cross-sectional area of the associated heating element, thereby ensuring retention of the associated heating element without significantly impeding air flow through the associated heating element.
  • the heating elements are of course so positioned in the associated passages that substantially all air flow in the passages is constrained to flow through the cores of the heating elements.
  • the holder is also adapted to receive substantially all air flow from the forward venturi opening 58.
  • the rear holder member 74 has a rectangular circumferential lip 100 dimensioned to fit about a corresponding lip 102 of the fan casing 54. Air flow from the forward venturi opening 58 is consequently directed against the rear holder face 80, and a large recess 104 is formed in the rear holder face 80 adjacent to and in general axial alignment with the forward venturi opening 58, to receive the air flows.
  • Each of the passages (such as the passages 96, 98) in which the heating elements are positioned has its rear passage opening located within the recess 104, spaced forwardly of the forward venturi opening 58. As will be apparent in fig.
  • the passages 96, 98 flare radially outwardly and rearwardly from the rear face of each associated heating element 28, 32 respectively to the associated rear passage opening.
  • the recess 104 flares radially outwardly and rearwardly from about the rear passage openings to the rear holder face 80. Accordingly, substantially all air escaping from the forward venturi opening 58 is delivered in a relatively smooth fashion to the heating elements.
  • the diameter of the apertures on the plate 114 is marginally smaller than that of the neating elements to ensure electrical contact.
  • a metal terminal strip 116 is spot welded to the plate 108, and extends to points external of the heater element holder, when assembled, to permit line voltage to be conveniently applied,to the plate 108.
  • a groove 118 is formed in the inner face 78 of the forward holder member 76, and is dimensioned to receive the terminal strip 116 loosely.
  • the conductive plate 110 provides electrical contact with the rear faces of the heating element cores, and seats against the inner face 82 of the rear holder member, in a manner analogous to the seating of the plate 108.
  • the structure and function of the two plates 108, 110 is substantially identical, and consequently no further detail will be provided regarding the plate 110.
  • the holder members 72, 74 are drawn together to contain the heating elements in the pockets by means of four fasteners. Since the fasteners are identical, only one fastener 120 has been specifically illustrated and indicated, in fig. 2.
  • the fastener 120 consists basically of a bolt 122, and coil spring 124 and a nut 126.
  • the heating element holder is first loosely assembled, for example, by seating the plate 110 against the inner face 82 of the rear holder member 74, positioning the heater elements appropriately over the apertures in the plate 110, seating the plate 108 against the inner face 78 of the forward holder member 72, and then carefully bringing'the holder members 72, 76 together in an operative orientation.
  • the holder members 72, 74 then have four pairs of aligned apertures, only the apertures 128, 130 being specifically indicated, which extend fully between the forward and rear holder faces 76, 80.
  • the coil spring 124 is located about the shaft 132 of the bolt 122, and the shaft extended fully through the aligned apertures 128, 130.
  • the nut 126 is then threaded onto the rear shaft end portion 134 until the nut 126 abuts the rear holder face 80.
  • the coil spring 124 which has a larger diameter than the apertures 128, 130, locates in the process about a forward shaft end portion 136, and acts between the bolt head and the forward holder face 76 to draw the holder members 72, 74 together.
  • a shallow well 140 is located about the aperture 128 in the forward holder face 76 and dimensioned to receive a portion of the coil spring 124.
  • a metal grill 142 is interposed between the bolt head of each fastener and the associated coil spring to fasten the grill directly to the forward holder member 72, but the grill 142 could equally well be attached to the abutment flanges 116 of the main housing member 12.
  • the four fasteners being spring-loaded permit separation of the holder members 72, 74 in response to thermal expansion of the heating elements. This arrangement is critical, as the ceramic holder members 72, 74 are very brittle, and could otherwise be easily cracked during operation cf the heater 10.
  • the heating element holder and grill 142 when assembled together are then attached to the fan casing 54.
  • This attachment is effected by passing the rear shaft portions of the various fasteners through apertures in the fan casing 54 and attaching additional nuts to the rear shaft end portions.
  • an aperture 143 in the fan casing 54 is aligned with the previously aligned holder member apertures 128, 130 and the rear shaft end portion 134 passed through the aperture 143 .
  • a nut 144 is then threaded onto the rear shaft end portion 134 to complete connection to the fan casing 54.
  • the electrical wiring and control circuitry associated with the heater 10 is schematically illustrated in fig. 5.
  • Line power is delivered via a power cord 152 (the two lines of the power cord being indicated with the same reference numeral 152) to the conductive plates 108, 110.
  • the electrical connection so formed is direct, involving no switching circuitry to control the amount of power delivered, except for a simple double pole single throw switch 154 which serves to turn the power to the heater 10 off and on.
  • the power consumed by the heating elements, and the heat consequently delivered is controlled entirely by varying fan speed with a fan control 156.
  • the fan control 156 includes as a primary switching element a bidirectional silicon controlled rectifier which permits substantially continuous variation of fan speed.
  • the temperature of the heating elements drops, but the resultant increase in conductivity of the heating element cores results in a marked increase in power consumption.
  • the quantity of heat delivered can be varied.
  • the required control circuitry and switches can be conveniently mounted to the rear housing insert 18 with appropriate wiring, as schematically illustrated, conducting power to the fan 52 and heating elements.
  • the heating elements had a total power consumption of about 1,200 W.
  • a noticable leakage of air backscattered through the rear fan venturi opening was also noted.
  • the preferred version substantially identical to the preferred embodiment 10 was operated under similar conditions, and a heating element power consumption of about 1,380 W was noted with no apparent leakage of air through the rear fan venturi opening. This represents about a 15% improvement in energy transfer to fan air flows. Additionally, on a purely qualitative basis, it was noted that the preferred version was considerably quieter in operation.

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  • Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Physics & Mathematics (AREA)
  • Thermal Sciences (AREA)
  • Combustion & Propulsion (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Ceramic Engineering (AREA)
  • Resistance Heating (AREA)
  • Direct Air Heating By Heater Or Combustion Gas (AREA)
EP86300809A 1985-02-11 1986-02-06 Appareil de chauffage électrique Withdrawn EP0204393A3 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
CA000474040A CA1231748A (fr) 1985-02-11 1985-02-11 Appareil de chauffage a elements chauffants semiconducteurs
CA474040 1985-02-11

Publications (2)

Publication Number Publication Date
EP0204393A2 true EP0204393A2 (fr) 1986-12-10
EP0204393A3 EP0204393A3 (fr) 1987-08-19

Family

ID=4129812

Family Applications (1)

Application Number Title Priority Date Filing Date
EP86300809A Withdrawn EP0204393A3 (fr) 1985-02-11 1986-02-06 Appareil de chauffage électrique

Country Status (3)

Country Link
EP (1) EP0204393A3 (fr)
CA (1) CA1231748A (fr)
DE (1) DE204393T1 (fr)

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE4104521A1 (de) * 1991-02-14 1992-08-20 Chang Chung Tai Ptc-heizelement
DE4404345A1 (de) * 1993-02-18 1994-08-25 Valeo Thermique Habitacle Elektrischer Heizradiator, insbesondere für den Fahrgastraum eines Kraftfahrzeuges
US5571432A (en) * 1992-04-21 1996-11-05 Valeo Thermique Habitacle Heating and ventilating apparatus for the cabin of a motor vehicle having a propulsion motor with relatively low heat loss
CN109595788A (zh) * 2019-02-13 2019-04-09 深圳热鑫能源科技有限公司 一种家用热水机

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE2410999A1 (de) * 1973-03-09 1974-09-12 Ngk Insulators Ltd Heizvorrichtung
DE2744639B2 (de) * 1977-10-04 1980-11-06 Petz Electro, Schmitten (Schweiz) Wandheizlüfter
GB2061075A (en) * 1979-10-11 1981-05-07 Tdk Electronics Co Ltd Ptc heating apparatus
GB1593924A (en) * 1977-03-07 1981-07-22 Tdk Electronics Co Ltd Heating element made of ptc ceramic material

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE2410999A1 (de) * 1973-03-09 1974-09-12 Ngk Insulators Ltd Heizvorrichtung
GB1593924A (en) * 1977-03-07 1981-07-22 Tdk Electronics Co Ltd Heating element made of ptc ceramic material
DE2744639B2 (de) * 1977-10-04 1980-11-06 Petz Electro, Schmitten (Schweiz) Wandheizlüfter
GB2061075A (en) * 1979-10-11 1981-05-07 Tdk Electronics Co Ltd Ptc heating apparatus

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE4104521A1 (de) * 1991-02-14 1992-08-20 Chang Chung Tai Ptc-heizelement
US5571432A (en) * 1992-04-21 1996-11-05 Valeo Thermique Habitacle Heating and ventilating apparatus for the cabin of a motor vehicle having a propulsion motor with relatively low heat loss
DE4404345A1 (de) * 1993-02-18 1994-08-25 Valeo Thermique Habitacle Elektrischer Heizradiator, insbesondere für den Fahrgastraum eines Kraftfahrzeuges
DE4404345B4 (de) * 1993-02-18 2006-05-24 Valeo Climatisation S.A. Elektrischer Heizradiator, insbesondere für den Fahrgastraum eines Kraftfahrzeuges
CN109595788A (zh) * 2019-02-13 2019-04-09 深圳热鑫能源科技有限公司 一种家用热水机

Also Published As

Publication number Publication date
CA1231748A (fr) 1988-01-19
EP0204393A3 (fr) 1987-08-19
DE204393T1 (de) 1987-06-11

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