FR2858166A1 - Electrical radiator for e.g. ventilation installation of motor vehicle, has heating block that is provided with heating units that couple based on their temperature levels and are maintained by bars - Google Patents

Abstract

The radiator (10) has a heating block (17) that is controlled by a control module (14). The heating block uses the heating units (19a, 19b) of type that has positive temperature coefficient. The heating units couple according to their temperature levels of that are different from each other. The heating units are maintained by bars and a heat radiating unit is installed between the bars. An independent claim is also included for ventilation installation.

Description

The technical sector of the present invention is that

  electric radiators installed in particular in a ventilation device, heating and / or air conditioning of a motor vehicle.

  It is known to use electric heaters in a ventilation system, heating and / or air conditioning to accelerate or increase the heat input inside the passenger compartment of a motor vehicle.

  These radiators generally consist of a heating block responsible for producing and exchanging thermal energy with an air flow present in the installation and a control module whose function is to control and regulate the block of air. heated. More particularly, the heating block 15 consists of bars which support resistive-type heating elements in the form of resistors with a positive temperature coefficient (hereinafter CTP). The use of PTC heating elements in fact permits temperature self-limitation so that overheating is avoided. The PTC heating elements are in the form of small blocks or "stones", arranged in the heating bars or between two electrodes. Radiant elements are associated with the bars to promote the heat exchange with the air flow passing through the installation. These radiant elements may be fins crossed by the bars or interleaves for example in the form of pleated or corrugated metal ribbons arranged between parallel bars.

  The additional electrical radiators CTP resistance work satisfactorily but have the disadvantage of requiring regulation by a control module. The latter must manage the block of heating by subdividing it to allow, in the case where the flow is cold, to heat this stream strongly, and in the case where the flow of air is lukewarm, to reduce the power in n '. supplying only a portion of the CTP heating elements.

  This control function requires a complicated electronic module because it includes many components. The main consequence is that the control module represents a significant part of the cost of a radiator that it would be good to reduce.

  The object of the present invention is therefore to overcome the disadvantages described above mainly by incorporating into the heating block PTC heating elements which, at intermediate temperatures, automatically engage in a stepped manner.

  The invention therefore relates to an electric heater 10 comprising a heating block controlled by a control module, said heating block using heating elements of the positive temperature coefficient type, characterized in that at least two of the heating elements engage at a different temperature level with respect to each other.

  According to a first characteristic of the invention, the heating elements are held by means of bars between which is installed a radiant thermal dispersion element.

  According to a second characteristic of the invention, the bars comprise two electrodes between which are stuck the heating elements.

  According to another characteristic of the invention, the contact between the electrodes and the heating elements is provided by a spring.

  According to another characteristic of the invention, the contact between the electrodes and the heating elements is ensured by gluing.

  According to yet another characteristic of the invention, the heating elements are distributed in separate bars.

  Each bar has at least two heating elements installed side by side.

  Advantageously, the heating elements are distributed in two consecutive bars so that said heating elements are arranged substantially opposite one another.

  Advantageously, the number of bars is between 3 and 6.

  According to one characteristic of the invention, the electric heater comprises eight heating elements which each engage at a different temperature level from each other.

  According to another characteristic of the invention, the temperature levels are staggered every 5 C.

  According to another characteristic of the invention, the electric radiator which is the subject of the invention is integrated in a ventilation installation, the latter possibly including optionally a liquid heat exchanger arranged upstream of the electric radiator.

  A first advantage according to the invention lies in the fact that the regulation of the temperature of the heating block is automatically staged. This staging is a direct consequence of the engagement of some heating elements while the others do not engage.

  Another advantage lies in the possibility of simplifying the electronic control circuit and thus reducing the cost of the radiator.

  Other characteristics, details and advantages of the invention will emerge more clearly on reading the description given below for information only in connection with drawings in which: FIG. 1 is a very schematic partial view of a ventilation apparatus , heating and / or air conditioning for a motor vehicle incorporating a radiator according to the invention, FIG 2 is a schematic view of a radiator 30 according to the invention, -3 is an illustration of the evolution of power by relative to the temperature in a radiator according to the invention.

  The drawings contain, for the most part, elements of a certain character. They can therefore not only serve to better understand the description, but also contribute to the definition of the invention if necessary.

  The entire description below uses the terms upstream and downstream. These terms should be interpreted according to the flow direction of the air flow in the duct in question.

  Figure 1 shows a part of a ventilation device, heating and / or air conditioning of a vehicle, comprising a housing 2 defining a channel 3 for the passage of air to be heated. This apparatus may be the main heat treatment unit of the vehicle usually installed under the dashboard but it may also be the subject of an additional apparatus dedicated to the heat treatment of the rear seats or a heat treatment apparatus specially dedicated to a seat of the motor vehicle. These three types of installation can be equipped with an evaporator for a cold thermal production.

  The description below is made by way of example in connection with a main heat treatment apparatus. The channel 3 brings the air to heating and defogging / defrosting vents to be selectively distributed in the passenger compartment according to the positions of 20 mixing and distribution flaps 6. The air flow in the channel 3 is produced by a fan 7, or blower, receiving outside air or recirculation air from the passenger compartment. The heating of the air, when necessary, is provided by a possible liquid heat exchanger 8, using the engine coolant as heat transfer fluid and by an electric radiator 10. The exchanger 8 and the radiator 10 are arranged in the channel 3, the first being located upstream of the second. In the absence of exchanger 8, the heating of the air is provided by the single electric radiator 10.

  The electric radiator 10 may occupy all or part of the passage section of the channel 3. In the latter case, only a part of the air flow produced by the blower 7 35 passes through the electric radiator, the other part being derived at the same time. outside of it.

  An embodiment of an electric heater 10 according to the invention will now be described with reference to FIGS. 2 and 3.

  As shown in Figure 2, the electric heater comprises a housing 12, for example plastic in which is housed a set of individual bars 13. These bars 13 are arranged parallel to each other 5 and extend over the entire length of the housing 12, so as to be exposed directly to the air passing through the radiator 10.

  Control of the electric radiator 10 is provided by a control module 14 mounted on a printed circuit board 10 advantageously housed in one of the sides of the housing 12 and protected by a cover 16.

  The control module 14 receives information through a connector (not shown) and is connected to a power source of the vehicle.

  The bars 13 are positioned in the heat exchange zone of the radiator, called the heating block 17. In addition to these bars 13, the heating block 17 consists of radiant elements 18 that promote thermal dispersion, for example corrugated fins, between heating elements 19a, 19b, 19c, 19d and the flow of air flowing in the channel 3.

  The heating elements 19a, 19b, 19c, 19d are ceramic stones of the positive temperature coefficient (PTC) type. These CTP stones have the particularity of self-regulating in intensity consumption. Indeed, at a certain temperature called Tref, the CTP stone increases its resistance very clearly and thus limits its need for electrical energy. The peculiarity lies in the fact that the CTP stones used in the radiator according to the invention are self-regulating at different temperature levels with respect to each other.

  Indeed, the heating element 19a increases its resistance to a reference temperature Tref equal to 20 C, the heating element 19b increases its resistance to a reference temperature Tref equal to 15 C, the heating element 19c increases its resistance at a reference temperature Tref equal to 10 C and the heating element 19d increases its resistance to a reference temperature Tref equal to 5 C. There is described here a radiator using 4 heating elements which engage at a different level of Tref but it is understood that the electric heater can integrate as many heating elements latching to a different level than necessary.

  In the example illustrated in FIG. 2, the heating elements 19a, 19b, 19c, 19d are distributed in separate bars 13 so as to homogenize the heating curve over the entire heating block 17.

  Inside a bar 13, the heating elements 19a, 19b, 19c, 19d are also distributed separately and in an order that makes it possible to homogenize the heating even within a bar 13.

  Thus, it can be seen that the heating elements 19a which all engage at a reference temperature equal to 15 ° C. are aligned in such a way as to form virtually a diagonal within the heating block 17. The same is true for the other elements heaters 19b, 19c, and 19d.

  Each bar 13 is constituted by two electrodes 20 and 21 between which are arranged the heating elements 19a, 19b, 19c, 19d which engage in different temperature levels relative to each other.

  The electrical and thermal contact between these electrodes 20, 21 and the heating elements 19a, 19b, 19c, 19d can be provided by means of a spring (not shown) or by gluing.

  The thermal contact between the radiant elements 18 and the electrodes 20 or 21 is ensured by contact under pressure, bonding, welding and more particularly by brazing.

  These electrodes conduct the electric current of the control module 14 to the heating elements 19a, 19b, 19c, 19d.

  The operation of the radiator according to the invention will be described hereinafter with reference to FIG.

  The heating block 17 which incorporates heating elements 19a, 19b, 19c, 19d which engage in different temperature levels relative to each other allows to lighten the control module 14. Indeed, as a part of the regulation is performed intrinsically by the heating elements, the control module can save some electronic control components such as transistors or power relays in particular. The cost of the control module is thus reduced.

  This self-regulation is illustrated by the graph of FIG. 3. This graph illustrates a radiator including eight heating elements which each engage at a different temperature level Tref according to a scale of 5 C at 5 C.

  At -20 C all heating elements are switched on and release maximum energy to the airflow. At -15 C one-eighth of the heating elements stops their consumption of electric current because they reached their Tref, at 15 10 C two eighths of the heating elements reach their Tref, at -5 C three eighths of the heating elements cease their electrical consumption.

  At 0 C, half of the heating body 17 is at a standstill, at +5 C only 3 types of heating elements disperse energy towards the air flow, at +10 C three-quarters of the heating elements are stopped and at +15 C, there remains only one type of heating elements in action.

  The above temperatures are given for information only without the heat input of the heat exchanger 8. The staggering and the temperature level can be adapted for use with a heat exchanger 8. In this variant, the staggering ranges from 20 C to + 50 C.

Claims (13)

  An electric radiator (10) comprising a heating block (17) controlled by a control module (14), said heating block (17) utilizing positive temperature coefficient type heating elements (19) characterized by at least two of the heating elements (19a, 19b) engage at a different temperature level with respect to each other.   2. Electric radiator according to claim 1, characterized in that the heating elements (19a, 19b, 19c, 19d) are held by means of bars (13) between which is installed a radiant element (18) of thermal dispersion.   3. Electric radiator according to claim 2, characterized in that the bars (13) comprise two electrodes (20, 21) between which are wedged the heating elements (19a, 19b, 19c, 19d).   4. An electric radiator according to claim 3, characterized in that the contact between the electrodes (20, 21) and the heating elements (19a, 19b, 19c, 19d) is provided by a spring.   5. Electric radiator according to claim 3, characterized in that the contact between the electrodes (20, 21) and the heating elements (19a, 19b, 19c, 19d) is provided by gluing.   6. Electric radiator according to any one of claims 2 to 5, characterized in that the heating elements (19a, 19b, 19c, 19d) are distributed in separate bars (13).   7. Electric radiator according to any one of claims 2 to 6, characterized in that each bar (13) comprises at least two heating elements (19a, 19b) installed side by side.   8. Electric radiator according to any one of claims 2 to 7, characterized in that the heating elements (19a, 19b, 19c, 19d) are distributed in two consecutive bars (13) so that said heating elements are arranged substantially opposite each other.   9. Electric radiator according to any one of claims 2 to 8, characterized in that it comprises between 3 and 6 bars (13).   10. Electric radiator according to any one of claims 2 to 9, characterized in that it comprises eight heating elements which each engage at a temperature level different from each other.   11. Electric radiator according to claim 10, characterized in that the temperature levels 10 are staggered every 5 C.   12. Ventilation installation characterized in that it incorporates an electric radiator (10) according to one of the preceding claims.   13. Ventilation installation according to claim 12 wherein is installed a liquid heat exchanger (8) disposed upstream of the electric radiator (10).