GB2071426A - Carburettors Inductive Couplings - Google Patents

Abstract

A carburettor comprises a housing 1 having an intake passage 2, a rotatable throttle plate 3 for opening and closing the intake passage, spring means 8 for biasing the throttle plate 3 to close the intake passage, a first rotor 9, e.g. an aluminium plate connected to the throttle plate 3 for rotation therewith, an electrically driven constant speed motor 15, a second rotor 14 rotatable by the said motor 15, and a variable inductive coupling between the rotor 9 and the rotor 14 to rotate the rotor 9 and throttle plate 3 against the biasing means 8 in response to rotation of the rotor 14. In the arrangement shown, a current is passed through a coil 12, e.g. under the control of a micro- processor; the magnetic field thus produced in a stator 10 induces a magnetic field in the rotor 14, and this latter field causes eddy currents to be produced in the rotor 9. The inductive coupling thereby produced between the first and second rotors varies in accordance with the magnitude of the current in the coil 12. <IMAGE>

Description

SPECIFICATION Carburettor This invention relates to carburettors.

Conventional carburettors for motor vehicle engines comprise a housing having an intake passage, a throttle plate for opening and closing the intake passage rotatably mounted in the housing, and a mechanical linkage for rotating the throttle plate in response to the movement of, for example, a pedal.

It is desirable, for fuel economy and control of exhaust emissions, to control a carburettor electronically, for example by means of a microprocessor so that the optimum fuel mixture can be fed to the engine under all operating conditions.

According to the present invention there is provided a carburettor comprising a housing having an intake passage, a rotatable throttle plate for opening and closing the intake passage, means for biasing the throttle plate to close the intake passage, a first rotor connected to the throttle plate for rotation therewith, an electrically driven motor, a second rotor rotatable by the said motor, and a variable inductive coupling between the first rotor against the biasing means in response to rotation of the second rotor.

Since the position of the rotor is controlled electrically through the inductive coupling means, a direct mechanical linkage between the caburettor and an operating pedal can be dispensed with, allowing the position of the throttle valve to be determined by means of a micro-processor operating in response to electrical instruction signals from an operating pedal.

The inductive coupling may take any suitable form. For example one rotor may comprise a permanant magnet. With this arrangement the second rotor could be driven by 9 variable speed motor.

Preferably however, the inductive coupling includes an electromagnet, which has a magnetic field the intensity of which can be varied by varying the current therethrough. With this arrangement a constant-speed motor may be used to drive the second rotor.

In the preferred embodiment of the invention, the electromagnet comprises a stator relative to which both rotors are rotatable, and a coil for reducing a magnetic field therein.

A preferred embodiment of the invention will now be described, by way of example only, with reference to the drawing, which is a schematic cross section through a carburettor.

Referring to the drawing the carburettor comprises a housing 1 having an intake passage 2 therethrough, which can be opened and closed by a butterfly-type throttle plate 3 rotatably mounted in the housing 1 by means of a drive shaft 4.

When the plate 3 is open, air can pass down the passage 2 (as seen in the drawings). The flow of air through a venturi 6 above the throttle plate 3 draws fuel into the carburettor through a metering orifice 7 in a well known manner.

The shaft 4 is biased into a closed position, in which the plate 3 closes the passage 2, by means of a coil spring 8 acting between the shaft 4 and the housing 1.

The free end of the shaft carries an aluminium rotor plate 9 and is journalled in a stator 10 of magnetically susceptible material e.g. iron. A coil 1 2 within the stator generates a magnetic field therein, and the intensity of the field can be varied by altering the current flowing through the coil.

A second rotor 14 is also rotatable relative to the stator by means of a constant speed electrical motor 1 5. The second rotor 14 is so positioned in relation to the stator 10 that a magnetic field is induced therein when the coil 12 is energised.

In use, the motor 1 5 is driven at constant speed throughout the period of operation of the carburettor. If no current is present in the coil 12, the throttle plate 3 will be kept closed by the spring 8.

To open the plate 3, a current is passed through the coil 12. This induces a magnetic field in the second rotor 14 which in turn generates eddy currents in the rotor plate 9. The resulting magnetic fields interact to cause the rotor plate 9 and hence the drive shaft 4 to rotate in the same direction as the second rotor 14 and against the bias of the spring 8. The shaft 4 will move into an equilibrium position in which the throttle plate is partly open. The position of the plate 3 can therefore be controlled by varying the current in the coil 12, thus allowing the carburettor to be operated electronically from a microprocessor.

Claims

1. A carburettor comprising a housing having an intake passage, a rotatable throttle plate for opening and closing the intake passage, means for biasing the throttle plate to close the intake passage, a first rotor connected to the throttle plate for rotation therewith, an electrically driven motor, a second rotor rotatable by the said motor, and a variable inductive coupling between the first rotor and the second rotor to rotate the first rotor against the biasing means in response to rotation of the second rotor.

2. A carburettor according to claim 1 wherein the inductive coupling comprises an electromagnet for inducing a magnetic field in one of the rotors, and means for varying the intensity of the magnetic field generated thereby.

3. A carburettor according to claim 2 wherein the electromagnet comprises a stator relative to which the rotors are rotatable and a coil for inducing a magnetic field therein.

4. A carburettor substantially as hereinbefore described and as illustrated in the accompanying drawings.

**WARNING** end of DESC field may overlap start of CLMS **.

Claims (4)

**WARNING** start of CLMS field may overlap end of DESC **. SPECIFICATION Carburettor This invention relates to carburettors. Conventional carburettors for motor vehicle engines comprise a housing having an intake passage, a throttle plate for opening and closing the intake passage rotatably mounted in the housing, and a mechanical linkage for rotating the throttle plate in response to the movement of, for example, a pedal. It is desirable, for fuel economy and control of exhaust emissions, to control a carburettor electronically, for example by means of a microprocessor so that the optimum fuel mixture can be fed to the engine under all operating conditions. According to the present invention there is provided a carburettor comprising a housing having an intake passage, a rotatable throttle plate for opening and closing the intake passage, means for biasing the throttle plate to close the intake passage, a first rotor connected to the throttle plate for rotation therewith, an electrically driven motor, a second rotor rotatable by the said motor, and a variable inductive coupling between the first rotor against the biasing means in response to rotation of the second rotor. Since the position of the rotor is controlled electrically through the inductive coupling means, a direct mechanical linkage between the caburettor and an operating pedal can be dispensed with, allowing the position of the throttle valve to be determined by means of a micro-processor operating in response to electrical instruction signals from an operating pedal. The inductive coupling may take any suitable form. For example one rotor may comprise a permanant magnet. With this arrangement the second rotor could be driven by 9 variable speed motor. Preferably however, the inductive coupling includes an electromagnet, which has a magnetic field the intensity of which can be varied by varying the current therethrough. With this arrangement a constant-speed motor may be used to drive the second rotor. In the preferred embodiment of the invention, the electromagnet comprises a stator relative to which both rotors are rotatable, and a coil for reducing a magnetic field therein. A preferred embodiment of the invention will now be described, by way of example only, with reference to the drawing, which is a schematic cross section through a carburettor. Referring to the drawing the carburettor comprises a housing 1 having an intake passage 2 therethrough, which can be opened and closed by a butterfly-type throttle plate 3 rotatably mounted in the housing 1 by means of a drive shaft 4. When the plate 3 is open, air can pass down the passage 2 (as seen in the drawings). The flow of air through a venturi 6 above the throttle plate 3 draws fuel into the carburettor through a metering orifice 7 in a well known manner. The shaft 4 is biased into a closed position, in which the plate 3 closes the passage 2, by means of a coil spring 8 acting between the shaft 4 and the housing 1. The free end of the shaft carries an aluminium rotor plate 9 and is journalled in a stator 10 of magnetically susceptible material e.g. iron. A coil 1 2 within the stator generates a magnetic field therein, and the intensity of the field can be varied by altering the current flowing through the coil. A second rotor 14 is also rotatable relative to the stator by means of a constant speed electrical motor 1 5. The second rotor 14 is so positioned in relation to the stator 10 that a magnetic field is induced therein when the coil 12 is energised. In use, the motor 1 5 is driven at constant speed throughout the period of operation of the carburettor. If no current is present in the coil 12, the throttle plate 3 will be kept closed by the spring 8. To open the plate 3, a current is passed through the coil 12. This induces a magnetic field in the second rotor 14 which in turn generates eddy currents in the rotor plate 9. The resulting magnetic fields interact to cause the rotor plate 9 and hence the drive shaft 4 to rotate in the same direction as the second rotor 14 and against the bias of the spring 8. The shaft 4 will move into an equilibrium position in which the throttle plate is partly open. The position of the plate 3 can therefore be controlled by varying the current in the coil 12, thus allowing the carburettor to be operated electronically from a microprocessor. Claims

1. A carburettor comprising a housing having an intake passage, a rotatable throttle plate for opening and closing the intake passage, means for biasing the throttle plate to close the intake passage, a first rotor connected to the throttle plate for rotation therewith, an electrically driven motor, a second rotor rotatable by the said motor, and a variable inductive coupling between the first rotor and the second rotor to rotate the first rotor against the biasing means in response to rotation of the second rotor.

2. A carburettor according to claim 1 wherein the inductive coupling comprises an electromagnet for inducing a magnetic field in one of the rotors, and means for varying the intensity of the magnetic field generated thereby.

3. A carburettor according to claim 2 wherein the electromagnet comprises a stator relative to which the rotors are rotatable and a coil for inducing a magnetic field therein.

4. A carburettor substantially as hereinbefore described and as illustrated in the accompanying drawings.