GB1584540A - Arrangements for preparation of fuel-air mixtures for internal combustion engines - Google Patents

Description

(54) IMPROVEMENTS IN OR RELATING TO ARRANGEMENTS FOR PREPARATION OF FUEL-AIR MIXTURES FOR INTERNAL COMBUSTION ENGINES (71) We, ROBERT BOSCH GMBH, a German company of Postfach 50, 7 Stuttgart 1, Federal Republic of Germany do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement: The present invention relates to apparatus for preparation of fuel-air mixtures for internal combustion engines.

One known arrangement for preparation of a fuel-air mixture in an air intake of an internal combustion engine having an arbitraily actuable throttle member, utilises a pivotal flap which extends transversely through the air intake and which is movable against a restoring force during its opening movement when it follows the throttle member. The flap maintains a predetermined minimum pressure drop when the throttle member is in its full-load position, and is therefore used to improve the preparation of the fuel-air mixture in the full-load range. With this arrangement there is, however, no improvement in the preparation of the fuel-air mixture when the engine is cold, a time when a particularly good preparation is desirable because of the cold air intake and cylinder walls.

According to the present invention there is provided an arrangement for the preparation of a fuel-air mixture in an air intake of an internal combustion engine, in which a throttle member in the air intake is arbitrarily angularly displaceable about an axis and is disposed in such a manner that in its idling or starting position it blocks the air intake and that during its opening movement air flow in the air intake only occurs on one side of the axis about which the throttle member is angularly displaceable. and in which a flap member co-operating with the throttle member is pivotally mounted coaxial with the throttle member is disposed in the air intake upstream of that portion of the throttle member along and around which air flows during opening movement of the throttle member and is pivotally displaceable by and in the direction of air flow in the air intake and against a temperature-dependently variable restoring force.

An arrangement embodying the present invention can have the advantage of improved preparation of the fuel-air mixture using simple means because of the increase in the pressure drop across the preparation member. Particularly advantageous is the increase in the pressure drop across the preparation member at low working temperatures of the engines below approximately 800C.

The invention will be further described, by way of example with reference to the accompanying drawing illustrating in a simplified manner one embodiment of the invention.

In the embodiment of the invention illustrated in the drawing, the intake combustion air flows downstream of an air filter (not shown) in the direction of the arrow into an air intake 1 having an air-flow measuring device in the form of for example a hot-wire air quantity meter 2, a throttle member 3 in the form of a butterfly valve and a preparation member 4 mounted coaxially with the butterfly valve, and thence to the individual cylinders (not shown) of an internal combustion engine. The butterfly valve 3 is journalled on a bearing axis 5 passing transversely through the air intake 1 and in its idling or starting position completely blocks the air intake.During an opening movement of the butterfly valve, one valve half 6 pivots against the direction of air flow into a correspondingly constructed intake portion 7 without opening a cross-section for air flow, while the other valve half 8 moving in the direction of air flow opens a cross-section for the flow of intake air. The preparation member 4, for example in the form of a flap 4, is journalled on the bearing axis 5 of the butterfly valve 3 unilaterally on the side of the valve half 8 facing the direction of air flow. A spring 10 acts as a restoring force upon the flap 4 and loads the flap against the direction of air flow. The end of the spring 10 remote from the flap is connected, for example, to a lever linkage 11, 12, 13 upon which a temperature-dependent operating element 14, for example an expansion member, acts at the other end.Downstream of the butterfly valve there is, for example, an electromagnetically actuated fuel injection valve 17 disposed in such a manner that the air flow directed through the butterfly valve or the preparation flap 4 is aimed as directly as possible at the fuel injection jet and envelops it. The fuel supply to the fuel injection valve is effected by means of a fuel pump 19 which is driven by an electric motor 18 and which draws in fuel from a fuel tank 20 and supplies it through a line 21 to the injection valve.

Branching off from the line 21 is a line 22 in which a pressure regulating valve 23 is disposed by means of which fuel can flow back to the fuel tank 20. Triggering of the electromagnetically actuable injection valve 17 is effected in a known manner by means of an electronic control device 25 in dependence upon the air intake quantity which is determined, for example, by a hot-wire air quantity meter. For adjustment of the quantity of fuel injected other measuring signals responsive to operating parameters of the engine may be supplied to the electronic control device. A bypass 26 which bypasses the throttle member 3 and whose cross-section is variable by means of a screw 27 serves for idling adjustment.

To improve preparation of the fuel-air mixture, according to the invention, at engine temperatures below approximately 80"C the initial tension of the spring 10 is increased so that. with the butterfly valve open as indicated at 3', the preparation flap 4' (as shown by the dashed lines) releases a smaller cross-section of flow because of the temperature-dependently increased restoring force so that there is a greater pressure drop at the preparation valve 4 for preparing the fuel injected through the injection valve 17.

WHAT WE CLAIM IS: l. An arrangement for the preparation of a fuel-air mixture in an air intake of an internal combustion engine. in which a throttle member in the air intake is arbitrarily angularly displaceable about an axis and is disposed in such a manner that in its idling or starting position it blocks the air intake and that during its opening movement air flow in the air intake only occurs on one side of the axis about which the throttle member is angularly displaceable. and in which a flap member cooperating with the throttle member is pivotally mounted coaxial with the throttle member is disposed in the air intake upstream of that portion of the throttle member along and around which air flows during opening movement of the throttle member and is pivotally displaceable by and in the direction of air flow in the air intake and against a temperature-dependently variable restoring force.

2. An arrangement as claimed in claim 1, in which the restoring force increases with decrease in temperature.

3. An arrangement as claimed in claim 1, in which the throttle member is a butterfly valve.

4. An arrangement as claimed in claim 1, in which the flap member is unilaterally journalled.

5. An arrangement as claimed in claim 2, in which a spring, upon whose end remote from the preparation member a temperature-responsive element acts, provides the restoring force on the flap member.

6. An arrangement for the preparation of a fuel air mixture for an internal combustion engine, constructed and arranged and adapted to operate substantially as hereinbefore particularly described with reference to and as illustrated in the accompanying drawing.

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

Claims (6)

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

   on the bearing axis 5 of the butterfly valve 3 unilaterally on the side of the valve half 8 facing the direction of air flow. A spring 10 acts as a restoring force upon the flap 4 and loads the flap against the direction of air flow. The end of the spring 10 remote from the flap is connected, for example, to a lever linkage 11, 12, 13 upon which a temperature-dependent operating element 14, for example an expansion member, acts at the other end. Downstream of the butterfly valve there is, for example, an electromagnetically actuated fuel injection valve 17 disposed in such a manner that the air flow directed through the butterfly valve or the preparation flap 4 is aimed as directly as possible at the fuel injection jet and envelops it.The fuel supply to the fuel injection valve is effected by means of a fuel pump 19 which is driven by an electric motor 18 and which draws in fuel from a fuel tank 20 and supplies it through a line 21 to the injection valve.

   Branching off from the line 21 is a line 22 in which a pressure regulating valve 23 is disposed by means of which fuel can flow back to the fuel tank 20. Triggering of the electromagnetically actuable injection valve 17 is effected in a known manner by means of an electronic control device 25 in dependence upon the air intake quantity which is determined, for example, by a hot-wire air quantity meter. For adjustment of the quantity of fuel injected other measuring signals responsive to operating parameters of the engine may be supplied to the electronic control device. A bypass 26 which bypasses the throttle member 3 and whose cross-section is variable by means of a screw 27 serves for idling adjustment.

   To improve preparation of the fuel-air mixture, according to the invention, at engine temperatures below approximately 80"C the initial tension of the spring 10 is increased so that. with the butterfly valve open as indicated at 3', the preparation flap 4' (as shown by the dashed lines) releases a smaller cross-section of flow because of the temperature-dependently increased restoring force so that there is a greater pressure drop at the preparation valve 4 for preparing the fuel injected through the injection valve 17.

   WHAT WE CLAIM IS: l. An arrangement for the preparation of a fuel-air mixture in an air intake of an internal combustion engine. in which a throttle member in the air intake is arbitrarily angularly displaceable about an axis and is disposed in such a manner that in its idling or starting position it blocks the air intake and that during its opening movement air flow in the air intake only occurs on one side of the axis about which the throttle member is angularly displaceable. and in which a flap member cooperating with the throttle member is pivotally mounted coaxial with the throttle member is disposed in the air intake upstream of that portion of the throttle member along and around which air flows during opening movement of the throttle member and is pivotally displaceable by and in the direction of air flow in the air intake and against a temperature-dependently variable restoring force.
2. 2. An arrangement as claimed in claim 1, in which the restoring force increases with decrease in temperature.
3. 3. An arrangement as claimed in claim 1, in which the throttle member is a butterfly valve.
4. 4. An arrangement as claimed in claim 1, in which the flap member is unilaterally journalled.
5. 5. An arrangement as claimed in claim 2, in which a spring, upon whose end remote from the preparation member a temperature-responsive element acts, provides the restoring force on the flap member.
6. 6. An arrangement for the preparation of a fuel air mixture for an internal combustion engine, constructed and arranged and adapted to operate substantially as hereinbefore particularly described with reference to and as illustrated in the accompanying drawing.