Patent Application
20140355966
The invention relates to an electrical heating device for a motor vehicle. The invention applies more particularly to heating and/or air-conditioning units of motor vehicles.
Conventionally, the heating up of the air intended for heating the passenger compartment of a motor vehicle, and also for defogging and defrosting, is carried out by the passage of a flow of air through a heat exchanger, more precisely by an exchange of heat between the flow of air and a liquid.
In general, this is the coolant in the case of a heat engine.
However, this mode of heating may prove unsuitable or insufficient to ensure rapid and effective heating of the passenger compartment of the vehicle, in particular to heat up the passenger compartment or to ensure defogging or defrosting before the vehicle is used in a very cold environment or else when a very rapid increase in the temperature is desired.
In the case of an electric vehicle, the heating function is no longer realized by the circulation of the coolant in the heat exchanger.
A water circuit may be provided to heat the passenger compartment.
This mode of heating may prove unsuitable or insufficient to ensure rapid and effective heating of the passenger compartment of the vehicle.
Furthermore, in order to reduce the space requirement and the costs on account of the additional water circuit, it is also known to use, for the electric vehicle, an air-conditioning loop that operates in a heat pump mode. Thus, the air-conditioning loop for cooling a flow of air in a conventional manner with the aid of a coolant fluid is used in this case to heat up the flow of air. For this purpose, it is appropriate to use an evaporator of the air-conditioning loop as a condenser.
However, this mode of heating may also prove unsuitable or insufficient. This is because the performance of the air-conditioning loop in the heat pump mode is dependent on outside climatic conditions; in this case, outside air at an excessively low temperature cannot be used as a source of heat energy.
In order to alleviate these drawbacks of the prior art, a known solution consists in adding an additional electrical heating device to the heat exchanger or to the water circuit or else to the air-conditioning loop.
Such an electrical heating device may be suitable for upstream heating of the liquid, such as the coolant for the heat engine, or the water for the water circuit for heating the passenger compartment of the electric vehicle or else the coolant fluid of the air-conditioning loop.
However, the known electrical heating devices may have a large head loss.
Therefore, the object of the invention is to propose an electrical heating device that has a reduced space requirement and makes it possible to reduce the head loss.
To this end, the subject of the invention is an electrical liquid heating device for a motor vehicle, said heating device comprising at least one module for heating said liquid, characterized in that said at least one heating module comprises:
The heating device may also have one or more of the following features, taken separately or in combination:
The invention also relates to a heating and/or air-conditioning unit for a motor vehicle, characterized in that it comprises an electrical heating device as defined above.
Further features and advantages of the invention will become more clearly apparent from reading the following description, given by way of nonlimiting and illustrative example, and from the appended drawings, in which:
In these figures, substantially identical elements have the same references.
The elements in
This heating unit comprises, upstream of the water heating circuit 3, an additional electrical heating device 5 for heating the water before it enters the heating circuit 3.
Shown here is the case of a water circuit for heating the passenger compartment of an electric vehicle.
Of course, it is also possible to provide for the electrical heating device 5 to be located upstream of the evaporator of an air-conditioning loop that is able to operate in a heat pump mode, so as to heat the coolant fluid.
It may also be possible to provide such an electrical heating device 5 upstream of a heat exchanger using the coolant of the heat engine as heat transfer liquid.
It may also be possible to provide such an electrical heating device 5 upstream of a heat exchanger intended to thermally regulate an electrical energy storage device, sometimes known as a battery pack, for an electric or hybrid vehicle.
With reference to
The heating device 5 has:
The heating module 7 is accommodated in an associated housing of the heating device 5.
This heating module 7 has an approximately cylindrical overall shape.
The heating module 7 comprises a central core 11 and an enclosure 13 having an approximately cylindrical shape, said enclosure 13 having a heating means and surrounding the central core 11.
The central core 11 and the enclosure 13 define a circuit 15 for guiding the liquid to be heated between the central core 11 and the enclosure 13.
Thus, the external surface of the central core 11 and the internal surface of the enclosure 13 define a circulation volume of the liquid to be heated. Elements for disrupting the flow of liquid in the guiding circuit 15 may be provided so as to increase the heat exchange between the liquid and the enclosure 13.
The central core 11 may be produced in the form of a hollow body.
This hollow, also known as the internal cavity 12 of the core 11, advantageously acts as an expansion vessel. Such an internal cavity 12 makes it possible to absorb the variations in volume of the liquid that result from the heating of this liquid.
Specifically, the internal cavity 12 of the central core 11 forms a reserve or a means for storing the heated liquid or heat transfer fluid. To this end, the central core 11 has a communicating passage 16 between the circuit 15 for guiding the liquid and the cavity 12 in the interior of the central core 11.
In addition, this means for storing the heated liquid allows the hydraulic circuit having such a heating device 5 to absorb the expansion of the heated fluid, as is shown in
More specifically, the internal cavity 12 contains air in its upper part and this air is able to be compressed under the effect of the expansion of the water. The upper part of the internal cavity 12, with reference to
The core 11 may also comprise an expansion control means.
This control means may be for example of the type of at least one calibrated passage, through which the heat transfer fluid is able to circulate. According to this variant, which is not illustrated, it is possible, for this purpose, to provide a fixed partition at the end of the core 11, which thus defines an internal volume of the expansion vessel and is provided with at least one calibrated passage, through which the heat transfer fluid is able to circulate.
According to another variant, which is not shown, the expansion control means may have a mobile partition that is able to slide along the internal cavity 12 of the core 11 with the expansion of the fluid.
Furthermore, it is possible for example to provide a reserve of heated liquid of around 0.4 to 0.5 L.
The central core 11 has for example an approximately cylindrical shape.
Provision may be made for the core 11 to have a section that is approximately constant or, by contrast, varying.
With an approximately constant section of the central core 11, the liquid flows at a constant speed through the guiding circuit 15.
By contrast, with a varying section, the speed of flow changes along the guiding circuit 15.
Moreover, according to the embodiment illustrated, the core 11 has an approximately helical external groove 17 on its external surface, that is to say facing the internal surface of the enclosure 13. On account of this helical groove 17, the guiding circuit 15 defines an approximately helical path.
Of course, provision may be made, as a variant, for the external surface of the core 11 to be without a groove, so as to define an axial guiding circuit parallel to the longitudinal axis A.
According to yet another variant, which is not shown, the core 11 may have a plurality of circular grooves on its external surface. In this case, a communicating orifice is provided in the region of each circular groove such that the interior of the core 11 communicates with the guiding circuit 15. Thus, the liquid passing into a heating module 7 flows inside the core 11 and around the core 11 in a circular manner.
For its part, of course, the enclosure 13 is produced in the form of a hollow body so that the central core 11 is received in the interior of the enclosure 13.
The central core 11 and the enclosure 13 may be concentric.
As mentioned above, the enclosure 13 comprises heating elements controlled by the control means 9 for heating the liquid by heat exchange between the enclosure 13 and the liquid circulating in the guiding circuit 15.
The enclosure 13 may for example have at least one resistive track connected to the control means 9 of the heating module 7.
The resistive track or tracks is/are produced for example by screen printing on the external surface of the enclosure 13, that is to say opposite the surface of the enclosure 13 facing the central core 11.
In addition, the enclosure 13 may have sealing means 18 positioned in the region of the ends of the enclosure 13.
For this exemplary embodiment, the heating means of the enclosure 13 is for example configured for power of around 2, 3, 4 or else 6 kW, depending on the application.
The heating device 5 also has at least one liquid inlet 19 and at least one liquid outlet 21 communicating with the guiding circuit 15 so as to allow the liquid to flow in the heating module 7.
This inlet 19 and outlet 21 are produced for example in the form of an inlet tube 19 and an outlet tube 21, respectively.
The inlet tube 19 and the outlet tube 21 are, for example, respectively positioned in a projecting manner with respect to the heating device 5. In the example illustrated, this inlet canal 23 and outlet canal 25 also form a projection with respect to the body of the heating device 5 accommodating the heating module 7.
The inlet tube 19 has an inlet canal 23 for the admission of the liquid. Similarly, the outlet tube 21 has an outlet canal 25 for the evacuation of the liquid.
The inlet canal 23 and outlet canal 25 may for example be respectively provided in the body of the device 5 perpendicularly to the longitudinal axis A of the cylindrical enclosure 13.
According to the example illustrated, the inlet canal 23 and outlet canal 25 are respectively provided in the body of the device 5 perpendicularly to the longitudinal axis A of the heating module 7.
The inlet canal 23 and outlet canal 25 extend for example approximately radially with respect to the cylindrical enclosure 13 and to the core 11, and thus, in this example, with respect to the heating module 7.
Moreover, the inlet canal 23 and outlet canal 25 may be positioned on two opposite sides of the heating module. The inlet canal 23 and outlet canal 25 may also be positioned in an opposing manner, that is to say at the two opposite ends of the device 5, as in the example in
Furthermore, for its part, the control means 9 may have at least one electric circuit support such as a printed circuit board, PCB, 27 and electronic and/or electrical components 29 carried by the support 27. These electronic and/or electrical components may for example comprise a microcontroller and electrical contacts connected to the resistive tracks of the enclosure 13. The electrical contacts are for example carried by a face of the PCB support 27 that is opposite the face that carries for example the microcontroller.
The support 27 may also carry at least one power and signal connector 31.
The heating device 5 may also have a protective cover 33 for the control means 9. This cover 33 has an opening for the connector 31 to pass through.
The control means 9 is arranged at a longitudinal end of the cylindrical enclosure 13 carrying the heating means.
In this case, the control means 9 is positioned in the region of the end of the housing of the heating device 5 accommodating the heating module 7. The device 5 thus has a support 35 for the control means 9 positioned so as to close this housing accommodating the heating module 7.
The support 35 for the control means 9 may be positioned in a manner bearing against the core 11 of the heating module 7, as the example in
In addition, the protective cover 33 for the control means 9 is fixed to this support 35 for the control means 9.
A sealing means 37 between the protective cover 33 for the control means 9 and the support 35 for the control means 9 may also be provided. This is for example an O-ring 37.
A heating device 5 that is thus produced makes it possible to limit the head loss while having a reduced space requirement compared with some solutions from the prior art.
A second embodiment of the heating device 105, shown schematically in
By contrast, in this second embodiment, the enclosure 113 has at least one opening 139 in which a heating means 114 is positioned.
The inlet canal 123 and outlet canal 125 lead into the heating device 105 around the enclosure 113. Thus, the enclosure 113 defines a circuit for guiding the liquid around the enclosure 113 accommodating the heating means 114.
In this case, the reserve of heated liquid is around the enclosure 113.
Moreover, in this second embodiment, the heating means 114 may have heating elements having a positive temperature coefficient. These are known as PTC heating elements.
These PTC heating elements are protected from overheating or an overcurrent.
The number of PTC heating elements is chosen depending on the power required in accordance with the application. A PTC heating element may for example be configured for power of around 500 W to 1 kW.
Each heating means 114 has two terminals 141 for connecting the PTC heating elements to electric potentials via the control means 109.
Thus, heating takes place by immersion of the PTC heating elements.
Moreover, the support 135 for the control means 109 is produced for example in one piece with the cylindrical enclosure 113.
According to this second embodiment, the enclosure 113 of the heating module 107 thus carries out, at the same time:
a function of accommodating the heating means 114,
a function of closing the housing of the device 105 accommodating the heating module 107, and also
a function of supporting the control means 109 of the heating module 107.
A heating device 105 produced in this way makes it possible to further decrease the head loss, and the transfer of heat energy is increased.
Finally, a third embodiment of the heating device 205 is illustrated in a simplified manner in
This third embodiment differs from the first embodiment in that the heating module 207 also does not have a central core surrounded by the cylindrical enclosure 213 so as to define the guiding circuit between the core and the enclosure.
By contrast, in this third embodiment, the cylindrical enclosure 213 bears for example against the internal walls of the body of the device 205, and the inlet canal 223 and outlet canal 225 lead into the interior of the cylindrical enclosure 213.
The guiding circuit 215 is thus defined in the interior of the cylindrical enclosure 213.
The device 205 also has a partition 243 which extends in the interior of the cylindrical enclosure 213.
By extending in the interior of the enclosure 213, the partition 243 creates turbulence in the flow of the liquid to be heated. This turbulence makes it possible to improve heat exchange.
In addition, this partition 243 may be produced in one piece with the support 235 for the control means 209.
In this case, the support 235 thus carries out, at the same time:
A heating device 205 produced in accordance with this third embodiment makes it possible to further decrease the head loss compared with the first and second embodiments.
Moreover, the reserve of heated liquid in the interior of the cylindrical enclosure 213 has a greater capacity than the second embodiment.
Finally, the transfer of heat energy is also improved compared with the second embodiment.
It will thus be understood that a heating device 5, 105, 205 produced in accordance with any one of the embodiments described above with one or more heating modules 7, 107, 207 as described, making it possible to define a guiding circuit in the interior of the heating module 7, 107, 207, makes it possible to limit the head loss while having a reduced space requirement.
| Number | Date | Country | Kind |
|---|---|---|---|
| 11/02698 | Sep 2011 | FR | national |
| Filing Document | Filing Date | Country | Kind | 371c Date |
|---|---|---|---|---|
| PCT/EP2012/003686 | 9/4/2012 | WO | 00 | 5/27/2014 |
