VENTILATION INSTALLATION FOR A MOTOR VEHICLE AND MOTOR VEHICLE COMPRISING SUCH AN INSTALLATION

Abstract

The installation (100) comprises: - a voltage source (BAT) designed to provide an input voltage (VBAT); - a capacitor (C3) designed to be connected to the voltage source (BAT) in order to be charged by an input current (IBAT) coming from the voltage source (BAT) to present a supply voltage (VALIM); and - a fan (VENT) connected to the capacitor (C3) to be powered by receiving the supply voltage (VALIM).The installation (100) further comprises: - an input current limiting resistor (R34) (IBAT) connected between the voltage source (BAT) and the capacitor (C3); - a switch (Q1) designed to selectively short-circuit the resistor (R34); and - a circuit (COM) for controlling the switch (Q1), designed to be electrically powered by the voltage source (BAT) in order to start when the voltage source (BAT) is connected to the capacitor (C3) and to close the switch (Q1) after a predefined time after its start. Figure for the abstract: Fig. 1.

Description

Title of the invention: VENTILATION INSTALLATION FOR A MOTOR VEHICLE AND MOTOR VEHICLE COMPRISING SUCH AN INSTALLATION Technical field of the invention

[0001] The present invention relates to a ventilation installation for a motor vehicle and a motor vehicle comprising such an installation. Technological background

[0002] A ventilation installation for a motor vehicle is known from the state of the art, comprising: - a voltage source; - a capacitor connected to the voltage source to be charged by an input current from the voltage source to present a supply voltage; and - a fan connected to the capacitor to be powered by receiving the supply voltage.

[0003] The voltage source is designed to provide a low voltage, i.e. less than 60 V, for example 12 V. When the voltage source is connected to the capacitor and when the voltage source is activated with the capacitor discharged, the capacitor is charged by the voltage source with an input current which can be high.

[0004] However, certain recent motor vehicle models include an eFuse system, which is an electrical circuit performing the function of a fuse. More precisely, this electrical circuit includes a comparator of the input current to an activation threshold and is designed to open a semiconductor switch when this activation threshold is exceeded. In such an eFuse system, the activation threshold is relatively low, so that it is necessary to limit the input current to avoid untimely triggering of the eFuse system.

[0005] Furthermore, in systems operating at high voltage, i.e. greater than 60 V, it is known to place a thermistor with a positive temperature coefficient for limiting the input current between the voltage source and the capacitor and to provide a switch in parallel with the thermistor, in order to selectively short-circuit it. This switch is then controlled by a control circuit designed to close the switch in order to short-circuit the thermistor when the capacitor is sufficiently charged.

[0006] This solution has the disadvantage that the thermistor is an expensive and bulky component.

[0007] Furthermore, the Japanese patent application published under the number JP 2009 195048 A proposes to use, in a high voltage DC-DC converter application, a fixed resistor and not a thermistor to limit the input current. A main switch is also provided in addition to the one in parallel with the limiting resistor, to selectively activate the voltage source by connecting it. The control circuit is thus designed to close the main switch and keep the parallel switch open for a predefined time following the closing of the main switch, this predefined time being chosen to be sufficient for the capacitor to have time to charge. At the end of this predefined time after the closing of the main switch, the control circuit closes the switch in parallel with the input current limiting resistor.

[0008] This solution has the disadvantage that the control circuit must be permanently switched on to control the closing of the main switch and start counting down the predefined time.

[0009] Furthermore, this solution is not compatible with conventional ventilation systems, which do not include a main switch. If the latter is present in the motor vehicle, it is then external to the ventilation system, so that the control circuit of the ventilation system cannot act on it. In other words, closing the main switch is an action undergone by the ventilation system.

[0010] It may thus be desirable to provide a ventilation installation for a motor vehicle which makes it possible to overcome at least some of the aforementioned problems and constraints. Summary of the invention

[0011] A ventilation installation for a motor vehicle is therefore proposed, comprising: - a voltage source designed to provide an input voltage; - a capacitor designed to be connected to the voltage source in order to be charged by an input current from the voltage source to present a supply voltage; and - a fan connected to the capacitor to be powered by receiving the supply voltage; characterized in that it further comprises: - an input current limiting resistor connected between the voltage source and the capacitor; - a switch designed to selectively short-circuit the resistor; and - a switch control circuit, designed to be powered electrically electrically by the voltage source in order to start when the voltage source is connected to the capacitor and to close the switch after a predefined time after its start.

[0012] Thus, thanks to the invention, it is possible to use, to limit the input current, both any resistance, preferably fixed because less expensive and bulky than a thermistor, and a control circuit powered only when the voltage source is activated. Thus, in the case of the presence of a general switch, the control circuit starts when the latter closes.

[0013] The invention may further comprise one or more of the following optional features, in any technically possible combination.

[0014] Optionally, the voltage source is connected to an electrical ground such that the input voltage is supplied relative to the electrical ground, the capacitor is connected to an electrical reference point such that the supply voltage is taken relative to the electrical reference point and the resistor is connected between the electrical ground and the electrical reference point.

[0015] Also optionally, the control circuit is connected to the capacitor to be powered by receiving the supply voltage.

[0016] Also optionally, the switch is a controllable semiconductor switch, such as a MOSFET, with a first terminal connected to the voltage source, a second terminal connected to the capacitor, and a control terminal.

[0017] Also optionally, the control circuit includes a control unit configured to provide a control signal and a driver configured to amplify the control signal into a control voltage provided to the switch.

[0018] Also optionally, the control unit comprises a microcontroller.

[0019] Also optionally, the installation further comprises a connected diode between the first terminal and the control terminal.

[0020] Also optionally, the resistor comprises two resistors in parallel with each other.

[0021] Also optionally, the fan is a heating, ventilation and air conditioning system fan.

[0022] Also optionally, the fan is a cooling fan for a motor driving the wheels of the motor vehicle.

[0023] A motor vehicle comprising an installation according to the invention is also proposed. Brief description of the figures

[0024] The invention will be better understood with the aid of the following description, given solely by way of example and with reference to the appended drawings in which: - [Fig.l] is a schematic view of an installation according to the invention for ventilation for a motor vehicle. Detailed description of the invention

[0025] With reference to [Fig.l], an installation 100 according to the invention for ventilation for a motor vehicle will now be described.

[0026] The installation 100 firstly comprises a voltage source BAT connected to an electrical ground GND and designed to provide an input voltage VBAT relative to the electrical ground GND.

[0027] The installation 100 further comprises a capacitor C3 designed to be connected to the voltage source BAT in order to be charged by an input current IB AT coming from the voltage source BAT to present a supply voltage VALIM relative to an electrical reference point REF.

[0028] To connect the voltage source BAT to the capacitor C3, the installation 100 comprises, for example, a general switch Q2 placed between the voltage source BAT and the capacitor C3. The installation 100 thus comprises a general control circuit 102 designed to control the general switch Q2, for example to close the latter when the ignition key is turned to start the vehicle.

[0029] The installation 100 further comprises a fan VENT connected to the capacitor C3 to be powered by receiving the supply voltage VALIM. The fan VENT is for example a fan of a heating, ventilation and air-conditioning system (also designated by the acronym HVAC). Alternatively, the fan VENT may be a cooling fan of a drive motor of the wheels of the motor vehicle, for example indirectly, by forcing air into a radiator to cool a coolant of the drive motor (thermal or electric).

[0030] The installation 100 further comprises a resistor R34 for limiting the input current IB AT, preferably fixed, connected between the voltage source BAT and the capacitor C3, for example between the electrical ground GND and the electrical reference point REF. By fixed resistance, we mean for example a resistor whose value varies by at most 500 ppm / °C, or 0.05% / °C over at least the temperature interval extending from -40°C to 100°C. Indeed, a fixed resistor has the advantage of being less expensive than a thermistor, and of fulfilling, within the framework of the invention, thanks to the presence of the switch Q1 which will be described later, the same function. For example, the resistor R34 comprises two resistors in parallel with each other. This allows the power flowing when charging capacitor C3 to be distributed between the two resistors, which is useful when it is not possible to find a re- usual resistance which, alone, could absorb this power without risk of failure.

[0031] The installation 100 further comprises a switch Q1 designed to selectively short-circuit the resistor R34.For example, switch Q1 is a semiconductor controllable switch, such as a transistor such as a metal-oxide gate field effect transistor (also known as MOSFET) or a silicon metal-oxide gate field effect transistor (also known as Si MOSFET) or a silicon carbide metal-oxide gate field effect transistor (also known as SiC MOSFET) or an insulated gate bipolar transistor (also known as IGBT) or a gallium nitride field effect transistor (also known as GaN FET).

[0032] The switch Q1 comprises a first terminal s (such as a source terminal) connected to the voltage source BAT, a second terminal d (such as a drain terminal) connected to the capacitor C3, the resistor R34 being connected between these two terminals s, d. The switch Q1 further comprises a control terminal g (such as a gate terminal). The switch Q1 is thus, for example, designed to be controlled according to the voltage between the control terminal g and the first terminal s.

[0033] The installation 100 comprises a circuit COM for controlling the switch Ql, designed for example to supply a control voltage Gate_En to the control terminal g relative to the first terminal s.

[0034] The control circuit COM is powered by the voltage source BAT. For example, the control circuit COM is connected to the capacitor C3 to be powered by receiving the supply voltage VALIM.

[0035] The installation 100 further comprises a Zener diode DI connected by its anode to the first terminal s of the switch Ql and by its cathode to the control terminal g of the switch QL. This Zener diode DI having a reverse voltage of for example 15 V has the function of limiting the voltage of the control terminal g with respect to the first terminal s, to substantially the reverse voltage so as to prevent this voltage from becoming too high (for example greater than 20 V), which would risk damaging the switch QL.

[0036] For example, the control circuit COM comprises a control unit 104, such as a microcontroller, designed to provide a control signal Enab and a driver 106 designed to amplify the control signal Enab into an intermediate voltage. The driver 106 comprises, for example, on the one hand, an amplifier AMP (for example a transistor amplifier) ​​designed to provide an intermediate voltage Int from the control signal Enab and, on the other hand, a voltage divider comprising two resistors RI, R2 connected to each other at a midpoint, the resistor RI is connected to the electrical ground GND and the resistor R2 receives the intermediate voltage Int. The midpoint thus presents the control voltage Gate_En.

[0037] The operation of the installation 100 will now be described.

[0038] Initially, the switch Q2 is open and the capacitor C3 is discharged. The supply voltage VALIM is low, for example zero, so that the control circuit COM is switched off.

[0039] At a time t1, the general control circuit 102 closes the switch Q2.

[0040] Resistor R34 limits the input current IBAT to (VBAT-VALIM) / R34, i.e. VBAT / R34 at the start of charging of capacitor C3, when the supply voltage VALIM is zero.

[0041] The supply voltage VALIM thus increases and reaches, at a time t2, a value sufficient for the control circuit COM to start. After starting, the control circuit COM counts down the predefined time T and, at the end of this time, closes the switch Q1 to short-circuit the resistor R34.

[0042] For example, the microcontroller 106 comprises a computer program designed to execute automatically after the start-up of the microcontroller 106. This computer program is designed to count down the predefined time T and to provide the control signal Enab for closing the switch Q1 at the end of this predefined time T, to the driver 106.

[0043] In conclusion, it appears clearly that a ventilation installation for a motor vehicle such as that described above makes it possible to limit the input current in a simple and inexpensive manner.

[0044] It will also be noted that the invention is not limited to the embodiments described above. It will indeed appear to those skilled in the art that various modifications can be made to the embodiments described above, in light of the teaching which has just been disclosed to them.

[0045] In particular, the presence of the switch Q2 is not essential. Indeed, the need for current limitation may only arise when (manually) connecting the 12V battery in the vehicle (during the manufacture of the car and when replacing this battery).

[0046] In the detailed presentation of the invention which is given above, the terms used should not be interpreted as limiting the invention to the embodiments set forth in the present description, but should be interpreted to include all equivalents the prediction of which is within the reach of those skilled in the art in application applying his general knowledge to the implementation of the teaching which has just been disclosed to him.

Claims

Claims

1. Ventilation installation (100) for a motor vehicle, comprising: - a voltage source (BAT) designed to provide an input voltage (VBAT); - a capacitor (C3) designed to be connected to the voltage source (BAT) in order to be charged by an input current (IBAT) coming from the voltage source (BAT) to present a supply voltage (VALIM); and - a fan (VENT) connected to the capacitor (C3) to be powered by receiving the supply voltage (VALIM); characterized in that it further comprises: - a resistor (R34) for limiting the input current (IBAT), preferably fixed, connected between the voltage source (BAT) and the capacitor (C3); - a switch (Ql) designed to selectively short-circuit the resistor (R34);and - a circuit (COM) for controlling the switch (Ql), designed to be electrically powered by the voltage source (BAT) in order to start when the voltage source (BAT) is connected to the capacitor (C3) and to close the switch (Ql) after a predefined time after its start.;

2. Installation (100) according to claim 1, in which the voltage source (BAT) is connected to an electrical ground (GND) so that the input voltage (VBAT) is supplied relative to the electrical ground (GND), the capacitor (C3) is connected to an electrical reference point (REF) so that the supply voltage (VALIM) is taken relative to the electrical reference point (REF) and the resistor (34) is connected between the electrical ground (GND) and the electrical reference point (REF).

3. Installation (100) according to claim 1 or 2, in which the control circuit (COM) is connected to the capacitor (C3) to be powered by receiving the supply voltage (VALIM).

4. Installation (100) according to any one of claims 1 to 3, in which the switch (Ql) is a semi-controllable switch. driver, such as a MOSFET, with a first terminal (s) connected to the voltage source (BAT), a second terminal (d) connected to the capacitor (C3) and a control terminal (g).

5. Installation (100) according to claim 4, in which the control circuit (COM) comprises a control unit (104) designed to provide a control signal (Enab) and a driver (106) designed to amplify the control signal (Enab) into a control voltage (Gate_En) supplied to the switch (Ql).

6. Installation (100) according to claim 5, in which the control unit (104) comprises a microcontroller.

7. Installation (100) according to any one of claims 4 to 6, further comprising a diode (Dl) connected between the first terminal (s) and the control terminal (g).

8. Installation (100) according to any one of claims 1 to 7, in which the resistor (R34) comprises two resistors in parallel with each other.

9. Installation (100) according to any one of claims 1 to 8, in which the fan (VENT) is a heating, ventilation and air conditioning system fan.

10. Installation (100) according to any one of claims 1 to 8, in which the fan (VENT) is a cooling fan of a drive motor of the wheels of the motor vehicle.

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