FR2784818A1 - RPM VARIATION MODULE OF AN ENGINE, IN PARTICULAR OF A PULSE OF A VENTILATION, HEATING AND / OR AIR CONDITIONING SYSTEM OF A MOTOR VEHICLE - Google Patents

Abstract

The invention relates to the field of engine speed variation modules, in particular of a blower for a ventilation, heating and / or air conditioning installation of a motor vehicle. It relates in particular to modules of the type comprising resistors (R1, R2, R3) and a switch capable of connecting or not at least one of these resistors between an electrical supply (V) and the motor (8). According to the invention, the switch comprises an electronic circuit with components (E, T) operating with an electric control current (C2, C3, C4) lower than an electric supply current of the motor (8), which allows limited switch wiring.

Description

Engine speed variation module, in particular a blower of a

  Installation of ventilation, heating and / or air conditioning of a motor vehicle The invention relates to a speed variation module of a

  motor, in particular a blower in a ventilation system

  tion, heating and / or air conditioning of a vehicle interior

automobile.

  A module of this type usually comprises several resistors connected, on the one hand, to an electrical supply and, on the other hand, to the motor, preferably by means of a module protection fuse. Such

  module generally includes a switch connected to the resist

  tances. For example, this switch may include one or more switches for short-circuiting at least one of the resistors, so that the motor operates according to a plurality of distinct speeds. In practice, food

  has a voltage source and each interrup-

  tor, occupying one or the other of its two positions, can

  define two separate voltages across the motor.

  A drawback that this type of module presents is linked to the fact that a strong current of electrical supply of the motor crosses the resistors and, more particularly, the components of the switch. In fact, the switches of known dimming modules generally require significant wiring to convey electrical currents of great intensities. A switch of this type, connected to a connector housed in the dashboard of the vehicle, must be

sized accordingly.

  Other known speed variation modules, based on electronic components, do not include an electrical resistance of the type described above. Their structure allows, through electronic controls, to obtain a continuous variation of the engine speed, and requires only a reduced wiring compared to the resistance modules described.

L -IX T

  above. However, such modules have components

  sophisticated electronics that add to their manufacturing cost

  tion. The present invention improves the situation. It then relates to a dimming module comprising at least one resistor and a switch suitable for connecting or not connecting one of the terminals of the resistor to an electrical supply, the other terminal of the resistor being connected to the motor. According to the invention, the switch comprises an electronic circuit with components capable of operating with an electric control current, substantially lower than a current

  power supply to the motor passing through the resistor.

  Thus, the module according to the invention retains a structure based on at least one electrical resistance, while the switch connected to this resistance operates on electronic controls of low current intensity, and does not

requires reduced wiring.

  In a more elaborate embodiment of the module according to the invention

  tion, this comprises a plurality of resistors, preferably mounted in series with a fuse

protection of the aforementioned type.

  In practice, the switch comprises means forming switches for short-circuiting or not at least one

  resistance and / or protection fuse.

  According to a particular embodiment of the invention, these means forming switches comprise at least one relay, of the winding type, and comprising an inductance coil. Advantageously, a diode is mounted in parallel

with this coil.

  As a variant, the switch means may comprise at least

  minus a power transistor, of the field effect type.

  The intensity of a control current which feeds a magnetic coil and / or the gate of a field effect transistor is advantageously much lower than the intensity of the current intended to pass through the resistors and to supply the motor. Preferably, the module comprises three resistors, while the switch comprises at least two switches so that the motor operates according to at least four

separate plans.

  According to a more elaborate embodiment, the switch has three switches so that the motor operates

according to eight distinct regimes.

  Other characteristics and advantages of the invention appear

  will examine the detailed description below, and

  attached drawings in which: - Figure 1A shows a top view of the serigrahiées resistors of a speed variation module of an engine, as well as their connections, - Figure lB represents a front view of the armature of the connections resistors shown in FIG. 1A, - FIG. 1C represents the equivalent diagram of the resistive circuit, with three resistors in series, in the example described, - FIG. 2 represents the electrical diagram of a speed variation module d ' an engine according to a first embodiment of the invention, FIG. 3 represents the electrical diagram of a speed variation module of an engine according to a second more elaborate embodiment, and FIG. 4 represents the electrical diagram d a module for varying the speed of an engine with means forming switches comprising field effect transistors,

  according to a third embodiment.

  The detailed description below and the attached drawings

  essentially include elements of a certain nature. They can not only serve to better understand the invention, but also contribute to its definition,

if applicable.

  Firstly, reference is made to FIG. 1A to describe the resistances of a speed variation module of an engine, according to the invention. The motor, in the example described, is

  intended to drive the turbine of a power unit in rotation

  fan, to produce a flow of ventilation air, so as to supply ventilated air to the passenger compartment of a vehicle

automobile (not shown).

  In the example, the variation module comprises three resistors R1, R2 and R3 which are produced in the form of

  resistive layers, screen printed on an insulated substrate.

  Preferably, the resistive layers are made of a material comprising impregnated glass strands. In order to remove heat from these resistors by the Joule effect, the aforementioned insulated substrate is made of a thermally conductive material, preferably a material comprising aluminum, and the substrate comprising the resistors is interposed in an air stream. in which a clean air flow circulates to supply the passenger compartment of the

vehicle.

  In practice, the thin layers are deposited according to patterns of thickness, width and respective length chosen,

i! __ T gl-

  so as to provide a numerical value for each resistance, according to Ohm's Law known to those skilled in the art: R = p / (eL) o p is the resistivity of the material, l the length of the pattern,

L its width and e its thickness.

  The three resistors R1, R2 and R3 are deposited on a film insulating the metal substrate, and are connected by tracks preferably made of copper P1, P2, P3, etc. Thus, in the example shown in Figure 1, the three resistors R1, R2 and R3 are connected in series. The ends of the patterns

  forming the terminals of the resistors are also connected

  ted to additional tracks (not shown) and connected to connection pins B1 and B2 for the resistor R1, B2 and B3 for the resistor R2, and B3 and B4 for the resistor R3. The insulated substrate S also carries a protective fuse F connected to the resistor R3, in series with

  this one. In the example described, this fuse F is a thermo

  fuse, capable of interrupting an electric current in the resistors, when the temperature of the substrate is higher than a temperature close to 184 C. As a variant, this fuse may be a so-called "temperature coefficient resistor"

  positive ", of increasing ohmic value with temperature.

  The terminals of fuse F are connected, via

  electrical tracks, to pins B4 and B5.

  The pins B1, B2, B3, B4 and B5 are preferably embedded in a frame 53, for example of plastic, and which has an opening 52 in a projection 51, to be fixed in an air ventilation duct, which allows advantageously to cool the metal substrate and, from there, allow the evacuation of the heat given off by the

resistances by Joule effect.

  In the example described, the motor M (FIG. 2) is supplied with voltage U. From a supply voltage V, close to 12 volts in the example, the resistors R1, R2 and R3 connected in series, act as a voltage divider bridge, and the value of the voltage U across the terminals of the motor M depends on the

  resistors that are connected and the supply voltage

  tion V. The term "connected" here designates the resistances crossed

  by a motor supply current, of significant intensity

  cative. For example, in the case where one of the resistors is short-circuited, the intensity of the current which crosses it is negligible compared to the supply current of the motor,

  and this resistor is not connected.

  It should also be noted that the fuse F has a specific resistance, predetermined, and whose value of the

  voltage U can depend, as we will see later.

  Thus, the resistances of the variation module screen printed on a substrate are interposed in an air stream of the above-mentioned heating and / or air conditioning ventilation installation. The pins B1 to B5 are usually connected to a switch, itself connected to a control member housed in a dashboard of the passenger compartment of the vehicle (not shown). The Bi pin is connected to a voltage source

  V and pin B5 is connected to motor 8 (Figure 2).

  According to the invention, the switch comprises an electronic circuit whose components are arranged to operate by means of a low electric control current, which makes it possible to limit the connection wiring between the switch

  and the resistive assembly of the module R1, R2, R3.

  We now refer to FIG. 2 to describe the equivalent diagram of a speed variation module according to a

  first embodiment of the present invention.

  In this embodiment, the switch comprises two winding relays E1 and E2, cooperating, in the example described, with a switch II and two switches I2 and 13, respectively. In practice, each winding includes an induction coil capable of opening or closing a switch

  whether or not to generate a magnetic induction flux. Advantageous-

  Each winding is connected, in parallel, to a diode D, which makes it possible to increase the performance of the inductance coils, according to a method known to those skilled in the art. Thus, the winding relays El and E2 are arranged to operate according to an electronic control in C2 and C3, respectively. When the switch Il is closed, the resistor R1 is short-circuited. When the switch I2 is closed, the resistors R2 and R3, as well as the fuse F, are short-circuited. Finally, when the switch I3 is closed, the resistors R1 and R2 are short-circuited. When the two electronic controls C2 and C3 are at a high level (V = 12 volts in the example), the three switches Il, I2 and I3 are open, and the equivalent resistance of the voltage divider bridge is substantially equal to the sum resistors Ri, R2, R3 added to the internal RF resistance of fuse F. The voltage U across the motor is close to

3 volts, in the example described.

  When the electronic control in C2 is at a low level

  (V = 0 volts in the example), while the electro-

  nique in C3 is at a high level, the equivalent resistance of the voltage divider bridge is substantially equal to a contact resistance of the switch Il added to the sum of the resistances R2, R3 and RF. The voltage U across the terminals

  of the motor is, in the example, close to 5 volts.

  When the electronic control in C2 is at a high level while the electronic control in C3 is at a low level, the resistance of the voltage divider bridge is equivalent to the paralleling of two resistors, one equivalent to the sum of 'a contact resistance of switch I2 and resistance R1, and the other equivalent to the sum of resistances R3, RF and a contact resistance of switch I3. The voltage U across the motor is

close to 7 volts, in the example.

  When the electronic controls in C2 and C3 are both at a low level, the resistance of the voltage divider bridge is equivalent to two contact resistances, that of switch II and that of switch I2. The voltage across the motor is around 12 volts. In practice, the switches Il, I2 and I3 are mounted astride two conductive tracks deposited on the insulated substrate S. The coils of the windings E1 and E2 are arranged opposite these switches, and are connected to the points C2 and C3 by l through reduced wiring, according to one

  main advantages that the invention provides.

  Reference is now made to FIG. 3 to describe a module for varying the speed of an engine according to a second embodiment of the present invention. In this second embodiment, the switch is connected to a third winding coil E3 to which a diode D3 is connected in parallel. This coil E3 is arranged to cooperate with a switch I4 able to open or close the connection between the resistor R3 and the fuse F. The relay formed by the coil E3 put in parallel with the diode D3, can be controlled from a electronic control in C4. As long as the electronic control in C4 is at a low level (V = 0 volts), the successive resistance values that the bridge can take

  voltage divider are equivalent to those described above

  before. In this second embodiment, the values of the resistances Ri, R2 and R3 are chosen so that the successive values which the voltage U can take at the terminals of the motor are close to 3 volts, 4 volts, 8 volts and 12 volts, in the configurations of the switches for which this voltage was 3 volts, 5 volts, 7 volts and 12 volts in the first embodiment described above. When the electronic controls in C3 and in C4 are both at a high level, the motor 8 is not supplied and its voltage U is practically zero, regardless of the fact that

  the switch It is open or closed.

  1etT1 -.1TT * If the electronic control in C4 is at a high level while the electronic control in C3 is at a low level, the resistance of the voltage divider bridge is equivalent to the resistance Ri added to the contact resistance of l 'switch I2, if the electronic control in C2 is at a high level. The voltage at the terminals of the motor is then, in the example described, approximately 6 volts. On the other hand, if the electronic control in C2 is at a low level, the resistance of the voltage divider bridge is equivalent to two contact resistances, that of switch II and that of switch I2, and the voltage across the terminals of U motor is close to 11.5 volts. Thus, in the first embodiment of the invention, the number of possible engine speeds with two relays is four, while in the second embodiment, the number of possible engine speeds is eight using

three relays.

  As a variant of the aforementioned second embodiment, provision may be made to equip the switch with transistors

  field effect power, in MOS technology.

  We then refer to Figure 4 to describe a module of

  variation according to a third embodiment of the invention

  tion. Each relay in FIG. 3 is replaced by a field effect transistor in FIG. 4. The gate of each transistor T1, T2, T3 and T4 receives an electronic command at C2, C3 and C3, C4, respectively. The source of transistor T1 is connected to the first terminal of resistor Ri, while the drain of T1 is connected on the one hand to the first terminal of resistor R2 and on the other hand to the source of transistor T2. The drain of T2 is connected to the motor 8. Furthermore, the source of T3 is connected to the first terminal of the resistor R1, while the drain of T3 is connected to the first terminal of R3. Finally, the source of T4 is connected to R3, while its drain is connected to fuse F. Thus, the transistor Tl is arranged to short-circuit the resistor Rl when it is on (control at a low level in C2). The transistor T2 is designed to short-circuit the resistors R2, R3 and the fuse F when it is on. The transistor T3 is arranged to short-circuit the resistors R1 and R2 when it is on. Finally, the transistor T4 is arranged to block or allow a current to flow between the resistor R3 and the fuse F.

  In this third embodiment using transis-

  field effect twists, these can be integrated directly into the insulated substrate S. They can be connected to points C2, C3 and C4 by wires of reduced diameter since the polarization of their grid does not require

  particularly large electric currents.

  In practice, the control currents in C2, C3 and / or C4 are at most close to 250 mA, while the electric currents flowing in the resistors R1, R2 and / or R3 are of the order

a few amps.

  Of course, the present invention is not limited to

  embodiments described previously by way of example.

  It extends to other variants.

  It will therefore be understood that the number of resistors used and the number of transistors and / or relays in association with switches, can be different depending on the

targeted applications.

  In the aforementioned third embodiment, the dimming module mainly comprises field effect transistors. An even different embodiment can be envisaged using both field effect transistors

  and winding relays of the type described above.

  Furthermore, the arrangement of the resistors in thin layers screen-printed on the substrate is also described by way of example. As a variant, the variation module can include

  classic resistors based on ceramic, preferential-

air cooled.

  In addition, the respective arrangements of the switches or of the transistors may be different from those described above. Provision may be made for a switch and / or a

  transistor for example in parallel with each of the resistors

  these. All or part of the module's resistors can also be mounted in parallel rather than in series, depending on

the targeted applications.

  The mounting of the diodes in parallel with the inductor coils

  tion here is optional, although advantageous.

  In a simplified variant of the module according to the invention, these

  diodes are likely to disappear.

  In addition, provision may be made for arranging diodes in parallel with each transistor of the circuit shown in FIG. 4,

  so as to improve its stability.

  Finally, the successive voltages U at the terminals of the motor are indicated here by way of example. Alternatively, their values

may be different.

Claims (14)

Claims   1. Engine speed variation module (8), in particular of a blower of a ventilation, heating and / or air conditioning installation of a passenger compartment of a motor vehicle, of the type comprising at least one resistance (R) and a switch suitable for connecting or not connecting one of the terminals of the resistor to a power supply (V), while the other terminal of the resistor is connected to the motor (8), characterized in that the switch comprises a circuit electronics with components (E, T) capable of operating with an electric control current (C2, C3, C4), substantially weaker than an electric power supply current to the motor (8),   crossing or not crossing said resistance (R).   2. Module according to claim 1, characterized in that it comprises at least one resistor (R1, R2, R3) produced in the form of a resistive layer, screen printed on a substrate isolated (S).   3. Module according to claim 2, characterized in that the resistive layer is made of a material comprising impregnated glass wires.   4. Module according to one of claims 2 and 3, characterized   in that the substrate (S) is made of a thermally conductive material, and in that it is interposed in   an air stream in which an air flow circulates.   5. Module according to claim 4, characterized in that the substrate (S) is made of a material comprising aluminum.   6. Module according to one of the preceding claims,   characterized in that the resistor (R) is connected to the motor via a protective fuse (F), of   predetermined self resistance.   7. Module according to one of the preceding claims,   characterized in that it comprises a plurality of resistors (R1, R2, R3) connected in series.   8. Module according to one of claims 6 and 7, characterized   in that the switch comprises switch means (I1, I2, I3, I4) for short-circuiting or not at least one resistance and / or fuse.   9. Module according to claim 8, characterized in that the   switch means include at least one coil relay   elements including an inductance coil (E1, E2, E3).   10. Module according to claim 9, characterized in that the switch means further comprises a diode (D1, D2, D3)   mounted in parallel with the coil.   11. Module according to one of claims 8 to 10, characterized   in that the switch means comprise at least one   field effect transistor (T1, T2, T3, T4).   12. Module according to claim 11 taken in combination with claim 2, characterized in that the transistor   (T1, T2, T3, T4) is integrated into the isolated substrate (S).   13. Module according to one of claims 8 to 12, characterized   in that it has three resistors (R1, R2, R3), while the switch has at least two switches so that the engine (8) operates at least four speeds separate.   14. Module according to claim 13, characterized in that the switch comprises three switches so that the   engine (8) operates at eight separate speeds.