FR2878316A1 - Electrical heating device for use in e.g. private vehicle, has case with zone traversed by air flow produced by propeller and comprising cells for receiving multiple heating units, multiple electronic interrupters and control circuit - Google Patents

Abstract

The device (10) has a case (11) comprising multiple parallel heating units (13), and a number of electronic interrupters (15) selectively acting on the heating units. A control circuit (17) assures control of the heating units through the interrupters. A zone of the case, traversed by an air flow (1) produced by a propeller, has cells for receiving the heating units, interrupters and control circuit. An independent claim is also included for a heating, ventilation and/or air conditioning appliance for a motor vehicle.

Description

Title of the invention

  Electric heating device, especially for heating, ventilation and / or air conditioning apparatus of a vehicle.

  BACKGROUND OF THE INVENTION The invention relates to an electric heating device for heating an air flow produced by an air flow generator, such as a blower or blower.

  The field of application of the invention is more particularly that of heating, ventilation and / or air-conditioning apparatus for vehicles, especially passenger motor vehicles, commercial vehicles and heavy goods vehicles.

  Usually, the heating of the air for heating the passenger compartment of a motor vehicle, as well as demisting and defrosting is ensured by passing a flow of air through a heat exchanger traversed by the coolant of the engine block.

  This heating mode may be unsuitable or insufficient in several situations such as: - preconditioning before starting the engine to ensure a warming of the passenger compartment, as well as defrosting or demisting, remotely or pre-programmed, before use the vehicle in a very cold environment, - the desired rapid increase of the temperature in the passenger compartment, - the inability of the heat exchanger to provide the necessary calories for a satisfactory reheating of the air to ensure the heating functions as well as the de-icing and defogging, as happens for some time after starting, with certain types of low heat loss engines.

  To overcome these drawbacks, a known solution, inter alia, is to add to the heat exchanger an electric heating device disposed downstream of the exchanger in the air flow duct to be heated. The operation of the electric heater is temporarily controlled until the heat exchanger alone can provide heating of the air as required.

  Usually, a complementary electric heater uses resistive elements mounted in a housing and powered through electronic switches.

  Indeed, such an electric heating device is described in particular in the French patent application No. 2,838,599 of the applicant. This electric heater comprises a housing having a plurality of heating modules exposed to a flow of air. Each heating module comprises a metal ribbon and an electronic switch for selectively prohibiting the power supply of the metal ribbon.

  Once the electric heater is mounted on the HVAC heater and / or air conditioning unit, part of the electrical heater with the heating module control circuit protrudes from the HVAC housing and thus clutches the passenger compartment. the automobile knowing that the volume of this part may represent about a quarter of the total volume of the electric heater.

  OBJECT AND SUMMARY OF THE INVENTION The object of the invention is to provide an electric heating device for a vehicle heater and / or air conditioning unit which has a simple and space-saving architecture in its mounting on the HVAC while allowing optimization. heat exchanges with air to heat.

  These objects are achieved by an electric heater for heating an air stream having a housing having a plurality of heating elements, a plurality of electronic switches selectively acting on said plurality of heating elements, and a control circuit. providing control of said plurality of heating elements (20) via said plurality of electronic switches, said pluralities of heating elements and electronic switches being mounted in an area of the housing through which the airflow passes, and that the control circuit is also mounted in the area of the housing through which the airflow passes.

  Thus, when the electric heater is mounted on the HVAC, the volume of the protruding portion of the HVAC housing is very small.

  According to one aspect of the invention, the housing comprises power supply and control connection means arranged outside said zone of the housing through which the airflow passes.

  Thus, the entire electrical and electronic part is integrated between the heating elements and only the control and power connections remain outside.

  According to another aspect of the invention, the plurality of heating elements corresponds to a plurality of individual heating modules arranged parallel to each other in the housing.

  According to yet another aspect of the invention, said zone traversed by the air flow comprises a plurality of longitudinal cells intended to accommodate the plurality of electronic switches, the plurality of heating modules, and the control circuit.

  According to a feature of the invention, the control circuit and the plurality of electronic switches are mounted in a central cell.

  The heating modules can be mounted in cells on either side of the central cavity.

  According to one embodiment of the invention, the control circuit and the plurality of electronic switches are mounted on an electronic card arranged parallel to the air flow.

  According to another embodiment of the invention, the control circuit and the plurality of electronic switches are mounted on an electronic card arranged perpendicularly to the air flow.

  Each heating module is connected to a corresponding electronic switch.

  Advantageously, each heating module comprises: PTC resistors arranged in a heating bar, and a first radiant element mounted on one face of the heating bar and a second radiant element mounted on the other side of the heating bar.

  The first and second radiant elements are arranged between first and second metal plates respectively.

  The first metal plate in contact with the first radiant element is connected to the corresponding electronic switch and the second metal plate in contact with the second radiant element is connected to ground.

  According to one variant, each heating module comprises a resistive element of undulating shape and an electrically insulating support.

  Advantageously, each heating module further comprises at least one thermal protection element.

  The invention also relates to a heating, ventilation and / or air conditioning apparatus for a motor vehicle comprising a heating device according to any one of the above characteristics.

Brief description of the drawings

  The invention will be better understood on reading the description given below, by way of indication but not limitation, with reference to the accompanying drawings, in which: - Figure 1 is a very schematic partial view of a heater, ventilation and / or air conditioning for a motor vehicle; FIG. 2 is a schematic view of a first embodiment of an electric heating device according to the invention; FIG. 3 is a perspective view of another embodiment of the electric heating device according to FIG. 2; FIG. 4 is a perspective view of a housing of the electric heating device of FIG. 3; - Figure 5 is a variant of Figure 3; FIG. 6 is an electrical diagram of the electric heating device according to the invention; FIG. 7 is a perspective view of a heating module of the electric heating device according to the invention; and - Figure 8 is a variant of Figure 7.

  Detailed Description of the Embodiments

  Figure 1 shows a part of a heater, ventilation and / or air conditioning of a motor vehicle, comprising a housing 2 defining a channel 3 for the passage of air to be heated. The channel 3 brings the air to the heating and defogging / defrosting vents 4, 5 to be selectively distributed in the passenger compartment according to the positions of mixing and distribution flaps 6. The air flow in the channel 3 is produced by a fan 7, or blower, receiving outside air and / or recirculation air from the passenger compartment. The heating of the air, when necessary, is provided by a heat exchanger 8, using the engine coolant as heat transfer liquid and by an electric heater 10. The exchanger 8 and the heating device 10 are arranged in the channel 3, the first being preferably located upstream of the second. In the absence of exchanger 8, the heating of the air is provided by the single electric heating device 10.

  The electric heating device 10 can occupy all or part of the passage section of the channel 3. In the latter case, only a part of the air flow 1 produced by the blower 7 passes through the electric heating device, the other part being derived outside of it.

  An embodiment of an electric heating device 10 according to the invention will now be described with reference to FIGS. 2 to 8.

  As shown in FIG. 2, the electric heating device 10 comprises a housing 11 having a plurality of heating elements 13, a plurality of electronic switches 15, for example in the form of power transistors acting selectively on the plurality of elements. heaters 13, and a control circuit 17 controlling the plurality of heating elements 13 via the plurality of electronic switches 15. These pluralities of heating elements 13 and electronic switches 15 are mounted in an area of the housing through which they pass. by the air flow 1 produced by the blower 7, that is to say that this zone of the housing is in the channel 3 for the passage of air to be heated.

  According to the invention, the control circuit 17 is also mounted in the region of the housing through which this airflow 1 passes.

  In addition, the electric heating device 10 comprises power supply and control connection means 19, comprising bus bars 21 and a connector 23, arranged outside the zone of the housing through which the air flow 1 passes.

  Thus, the entire electrical and electronic part 15, 17 is integrated in the housing 11 with the heating elements 13 and only remains outside the control and power connector 19. As a result, when the electric heater 10 is mounted on the HVAC, only the control and power connector 19 which does not have a large volume protrudes from the housing 2 defining the channel 3 of the HVAC.

  FIG. 3 illustrates another embodiment of the electric heating device 10 according to the invention, where the plurality of heating elements 13 corresponds to a plurality of individual heating modules 113, arranged parallel to each other in the housing 11, plus specifically in the area through which the airflow 1 passes so as to be exposed directly to this air passing through the housing 11.

  The use of individual heating modules 113 enables the heating elements 13 to be standardized, thus facilitating the manufacture and maintenance of these modules.

  FIG. 4 shows that the region of the housing 11 traversed by the air flow 1 comprises a plurality of longitudinal cells 27 intended to accommodate the plurality of electronic switches 15, the plurality of heating modules 113, and the control circuit 17 .

  Indeed, the housing 11 corresponds to a rectangular-shaped frame having longitudinal walls 29 which define between them a set of cells 27. By way of example, Figure 4 shows three cells 27, intended to accommodate and maintain in place two electronic switches 15, two heating modules 113, and the control circuit 17. Of course, this number is not limiting and may be different.

  Thus, as shown in the example of FIG. 3, the control circuit 17 and the electronic switches 15 can be mounted on the same electronic card 31 in a central cell 27 and the heating modules 113 can be mounted in cavities 27 of FIG. on either side 2878316 8 of the cell 27 central. Of course, the control circuit 17 can be mounted on an electronic card and the electronic switches can be mounted on another electronic card.

  The heating modules 113 are connected to a power source (not shown) through the bus bars 21, and the control circuit 17 receives information through the connector 23 and can be connected to the power source through the bus bars 21 or through the connector 23.

  In addition, this example shows that the electronic card 31 comprising the control circuit 17 and the electronic switches, has its main face disposed substantially perpendicular to the direction of flow of the air flow 1 through the housing 11. However, the electronic card 31 may comprise holes 33 making it possible to limit the pressure drop due to the passage of air in the electric heating device 10.

  As a variant, FIG. 5 shows that the electronic card 31 comprising the control circuit 17 and the electronic switches 15 has its main face disposed substantially parallel to the flow direction of the air flow 1 through the housing 11 so as to limit the pressure drop due to the passage of air in the electric heater 10. In this case, it is advantageous to share the electronic switches 15 between the two faces of the electronic card 31 to facilitate connection of each heating module 113 with its corresponding switch 15.

  Indeed, FIG. 6 very schematically illustrates the connection 25 between the control circuit 17, the electronic switches 15 and the heating modules 113 of the electric heating device 10.

  The control circuit 17 receives, via the connector 23, information, for example of logic type, conveyed by a data bus 41 and representative of the requested power level P, the control circuit 17 is further connected to a energy bus formed of a conductor 43a network potential + Vr available in the vehicle, for example the battery voltage, and a conductor 43b raised to the reference potential (ground). Alternatively, the control circuit 17 may be energized via the connector 23 and then its connection with the conductor 643a may be omitted.

  In the example of Figure 6, the heating modules 113 are two in number and the electronic switches 15 are also two in number because each heating module 113 is connected to a corresponding electronic switch 15.

  Thus, one terminal of each heating module 113 is connected to the conductor 43b via its corresponding electronic switch 15 while the other terminal of each heating module 113 is connected to the conductor 43a.

  In the case of excessive heating resulting from insufficient evacuation of the calories produced, for example when the air flow passing through a heating module 113 is less than a minimum value, the corresponding electronic switch 15, controlled by the control circuit 17 prohibits the power supply of the heating module 113.

  Furthermore, a signal representative of the speed of rotation of the blower 7 can be sent to the control circuit 17 to prohibit the power supply of the individual heating modules 113 when the speed of rotation of the blower 7 is below a predetermined threshold.

  It is possible to vary the power continuously or continuously by modulating the power supply voltage of the heating modules 113, or at least one of them. The modulation can be carried out by pulse width modulation (PWM), the voltage Vr being cut off in order to be delivered to the heating modules 113 in the form of a pulse train in which the ratio between widths and periods of the pulses is variable. Modulated simultaneous supply of all the heating modules 113 allows, regardless of the power level P, to evenly distribute the heat emission throughout the passage section of the air in the electric heater.

  FIG. 7 very schematically illustrates an embodiment of a heating module 113a having positive temperature coefficient resistors 51 (PTC) arranged in a heating bar 53, and a first radiant element 55a mounted on a face of the heating bar 53 and a second radiant element 55b mounted on the other face of the heating bar 53.

  The use of PTC resistors 51 indeed allows self-limiting temperature so that excessive heating is avoided. The PTC resistors 51 are in the form of small blocks or "stones", arranged in the heating bar 53, between two electrodes 57. The radiant elements 55a and 55b are associated with the heating bar 53 to promote the heat exchange with the heat flux. air 1 passing through the electric heating device 10. These radiant elements 55a and 55b may be fins or interleaves for example in the form of pleated or corrugated metal ribbons disposed on each side of the heating bar 53.

  In addition, the first and second radiant elements 55a and 55b may be disposed between first and second metal plates 59a and 59b respectively. Thus, the first metal plate 59a in contact with the first radiant element 55a is connected to the corresponding electronic switch 15, and the second metal plate 59b in contact with the second radiant element 55b is connected to ground. Optionally, the first and second radiant elements 55a, 55b can be directly connected to the electronic switch 15 and to the ground without the intermediary of the metal plates 59a, 59b.

  FIG. 8 very schematically illustrates another embodiment of a heating module 113b comprising a resistive element 61 of undulating shape and an electrically insulating support 63.

  Thus, the individual heating module 113b comprises a rigid and electrically insulating support 63 intended to receive and hold in position a same resistive element 61 in the form of a continuous metal strip of pleated or corrugated shape.

  The protection of the electric heater 10 against excessive heating is provided by the control circuit 17 and the electronic switches 15. However, for the sake of maximum safety, additional protection against excessive heating of the radiator is provided by means of at least one thermal protection element 65 in each individual heating module 113b. This protection element 65 is in series with the resistive element 61 and preferably must be directly exposed to the air passing through the heating module 113b.

  The protective element 65 may consist of a hot-melt connection formed by cutting the ribbon of the resistive element 61 and connection of its sections by soldering by means of a solder adapted or formed by a solder between one end of the resistive element 61 and one end of a spring blade (not shown).

  In addition, the protection element 65 may be a thermal sensor or detector delivering information to the control circuit 17, in adequacy with the temperature of the resistive element 61 so that the control circuit cuts off the power supply in case of failure. excessive heating.

Claims (15)

  An electric heater for heating an air flow (1) having a housing (11) having a plurality of heating elements (13), a plurality of electronic switches (15) selectively acting on said plurality of elements heaters (13), and a control circuit (17) controlling said plurality of heating elements (13) via said plurality of electronic switches (15), said pluralities of heating elements (13) and switches electronics (15) being mounted in an area of the bolter through which the airflow (1) passes, characterized in that the control circuit (17) is also mounted in the region of the housing through which the airflow (1 ).   2. Device according to claim 1, characterized in that it further comprises connection means (19) for power supply and control disposed outside said zone of the housing through which the air flow (1).   3. Device according to any one of claims 1 and 2, characterized in that the plurality of heating elements (13) corresponds to a plurality of individual heating modules (113) arranged parallel to each other in the housing (11) .   4. Device according to claim 3, characterized in that said area through which the air flow (1) has a plurality of cells (27) longitudinal to accommodate the plurality of electronic switches (15), the plurality of heating modules (113), and the control circuit (17).   5. Device according to claim 4, characterized in that the control circuit (17) and the plurality of electronic switches (15) are mounted in a cell (27) central.   6. Device according to claim 5, characterized in that the heating modules (113) are mounted in cells (27) on either side of the central cavity.   7. Device according to any one of claims 5 and 6, characterized in that the control circuit (17) and the plurality of electronic switches (15) are mounted on an electronic card (31) arranged parallel to the flow of air (1).   8. Device according to any one of claims 5 and 6, characterized in that the control circuit (17) and the plurality of electronic switches (15) are mounted on an electronic card (31) disposed perpendicular to the flow of air (1).   9. Device according to any one of claims 1 to 8, characterized in that each heating module (113) is connected to a corresponding electronic switch (15).   10. Device according to any one of claims 3 to 9, characterized in that each heating module (113a) comprises: -PTC resistors (51) disposed in a heating bar (53), and -a first radiant element (55a). ) mounted on one side of the heating bar and a second radiant element (55b) mounted on the other side of the heating bar.   11. Device according to claim 10, characterized in that the first and second radiant elements (55a, 55b) are arranged between first and second metal plates (59a, 59b) respectively.   12. Device according to claim 11, characterized in that the first metal plate (59a) in contact with the first radiant element (55a) is connected to the corresponding electronic switch (15) and in that the second metal plate (59b ) in contact with the second radiant element (55b) is connected to ground.   13. Device according to any one of claims 3 to 9, characterized in that each heating module (113b) comprises a resistive element (61) of undulating shape and an electrically insulating support (63).   14. Device according to claim 13, characterized in that each heating module (113b) further comprises at least one thermal protection element (65).   15. Heating, ventilation and / or air conditioning apparatus for a motor vehicle, characterized in that it comprises a heating device according to any one of claims 1 to 14.