GB2167126A

GB2167126A - Mixture-forming device for multicylinder internal combustion engines

Info

Publication number: GB2167126A
Application number: GB08524757A
Authority: GB
Inventors: Karl Schmidt; Hans-Jurgen Muller
Original assignee: Pierburg GmbH
Current assignee: Pierburg GmbH
Priority date: 1984-11-20
Filing date: 1985-10-08
Publication date: 1986-05-21
Also published as: GB8524757D0; FR2573486A1; IT1181732B; IT8548548A0

Abstract

Mixture is supplied to the inlets 8 of the branches 4 of a manifold containing a first air throttle valve (2, Fig. 1) by respective venturis 9 at the downstream ends of branch ducts 7 of a manifold 5 containing an operator controlled throttle valve 6. Fuel is delivered to the venturis 9 through respective outlets 10 of an electrically controlled metering valve 11. The valve 6 only is opened at low engine outputs, the first throttle valve being opened mechanically or pneumatically at higher engine outputs. <IMAGE>

Description

SPECIFICATION Mixture-forming device for multicylinder internal combustion engines The invention relates to a mixture-forming device.

From German Offenlegungsschrift 29 51 788, there is known a fuei-metering valve which is situated downstream of the throttle valve in the second air-induction channel, this throttle valve being actuated at will by the human operator of the engine. The fuel-metering valve sprays fuel into the aspirated air which flows at high speed at that location when the engine is running. The intention is to atomize and evaporate the fuel.

From the German Offenlegungsschrift 30 33 728 a central fuel-injection device is known which has spray-channels fed with fuel by an injection nozzle situated immediately upstream of a branching section. Through the spray channels, fuel is sprayed into the mouths of each of the induction channels leading to the individual cylinders of the engine. The intention here also is to ensure an even distribution of the fuel.

In the first of these two known devices the nozzle of the fuel-metering valve sprays the fuel into the air-induction channel in a direction perpendicular to the axis of the channel, producing a conical jet, with the consequence that the fuel is unevenly distributed. In the subsequent splitting up of the current of fuel to the individual induction channels for the several cylinders of the engine the combustible mixture becomes unevenly distributed.

In the second of these known devices the fuel is injected as a discrete jet into each of the individual induction channels, wetting the walls of the channels so that inadequate atomisation and evaporation occurs.

The intention in the present invention, starting from a device of the kind described at the beginning, is to improve the device in such a way as to ensure that a well atomised and evaporated combustible mixture is distributed evenly among the cylinders of the engine.

Accordingly, this invention provides a mixture-forming device for multi-cylinder internal combustion engines, with a first air-induction channel containing a throttle valve and with, branching out from this, individual inductionmanifold pipes leading to the individual cylinders of the engine; the mixture-forming device also having a second air-induction channel containing a second throttle valve, this one actuated at will by the human operator of the engine and, branching out from this, mixtureinduction channels which also lead out to the individual induction-manifold pipes; the two throttle valves being coupled together to act in parallel-sequential timing; the device being equipped with a fuel metering valve and being characterized in that each individual mixtureinduction channel leading to its individual induction-manifold pipe has, penetrating into the mouth of the induction-manifold pipe, a venturi constriction communicating with a jet-channel of the fuel metering valve of the carburettor.

The two throttle valves and are coupled together to open and close in "parallel sequential timing." By this phase we mean that the two valves are so coupled that during engine idling and at low engine torques only the second throttle valve is open. With increasing torque both the throttle valves come open and consequently, under all engine-operating conditions air travels at high speeds through the narrowest portion of the venturi. The first throttle valve can be actuated either mechanically or pneumatically.

The mixture-forming device of the invention, particularly when combined with an electronic controller, and with a fuel-metering valve controlled by the electronic controller, makes it possible to achieve an extremely precise distribution of the combustible mixture to the individual cylinders of the engine, bringing the advantage that the richness of the mixture supplied to the most deprived cylinder can be considerably reduced, with the consequence that fuel is saved, the vehicle behaves better on the road and the exhaust gases are cleaner.

The device of the invention is considerably less costly to manufacture than a device which has several fuel-metering valves.

A practical example of the invention is shown diagramatically in the drawing and will now be described in greater detail. In the drawing Figure 1 is a diagramatic representation of an internal combustion engine equipped with the mixture-forming device of the invention.

Figure 2 is a section of the distributor portion of the second air-induction channel, with its fuel-metering valve.

Fig. 1 shows an internal combustion engine 1 with a first air-induction channel 3 containing a throttle valve 2. From this air-induction channel 3 there branch off individual inductionmanifold pipes 4 leading to the individual cylinders of the engine. The mixture-forming device also has a second air-induction channel 5 containing a second throttle valve 6 which is actuated at will by the operator of the engine.

The two throttle valves 2 and 6 are coupled together to open and close with parallel-sequential timing, as described further below.

From the second air-induction channel 5 there branch off mixture-induction channels 7 leading to the individual induction-manifold pipes 4. Each mixture-induction channel 7 contains a enturi constriction 9 which penetrates downwards into the mouth 8 of its individual induction-manifold pipe 4. Communicating with the narrowest portion of each venturi constriction 9 there is the jet-channel 10 of a fuelmetering valve 11. Upstream of the throttle valves 2, 6 the two air-induction channels 3 and 5 are combined to form a common airinduction channel 12 equipped with a conventional air-flow meter 13 (not shown) which need not be described in detail here. The airflow meter 13 provides information on the rate of flow of the aspirated air.

The fuel-metering valve 11 shewn in Fig. 2 is controlled electromagnetically by an electronic controller 14 in response to the rate of flow of aspirated air, and to other engine and environmental variables.

Fig 2 shows a section through the fuelmetering valve 11, which is located in a distributor portion 15 of the second air-induction channel 5. The fuel-metering valve 11 has a fuel chamber 16, filled with fuel arriving under pressure through a fuel-feed channel 17 from a fuel pump (not shown), and a fuel-return channel 18 for returning excess fuel to a fuel tank (not shown). Projecting into the chamber 16 is a valve body 19 which controls the flow of fuel flowing through jet-channels 10 situated downstream of a valve seat 20 of the fuel-metering valve 11. The jet-channels 10 spray fuel under pressure into the venturi constriction 9 when the valve body 19 is lifted from the valve seat 20. The high velocity of the air in the narrowest portion of each venturi 9 atomises the fuel, so that a mixture of air and atomised fuel is aspirated into the mouth 8 of each induction-manifold pipe 4. At high air through-puts, with the first throttle valve 2 open, the air also flows at high speed where it enters the induction-manifold pipes 4, once more producing high turbulence and promoting good atomisation of the fuel.

The two throttle valves 2 and 6 are coupled together to open and close in "parallel sequential timing." By this phase we mean that the two valves are so coupled that during engine idling and at low engine torques only the second throttle valve 6 is open; with increasing torque both the throttle valves come open consequently, under all engine-operating conditions air travels at high speeds through the narrowest portion of the venturi 9. The first throttle valve 2 can be actuated either mechanically or pneumatically.

Claims

1. A mixture-forming device for multi-cylinder internal combustion engines, with a first air-induction channel containing a throttle valve and with, branching out from this, individual induction-manifold pipes leading to the individual cylinders of the engine; the mixture-forming device also have a second air-induction channel containing a second throttle valve, this one actuated at will by the human operator of the engine and, branching out from this, mixture-induction channels which also lead out to the individual induction-manifold pipes; the two throttle valves being coupled together to act in parallel-sequential timing; the device being equipped with a fuel metering valve and being characterised in that each individual mixture-induction channel 7 leading to its individual induction-manifold pipe 4 has, penetrating into the mouth 8 of the induction-manifold pipe 4, a Venturi constriction 9 communicating with a jet-channel 10 of the fuel metering valve 11 of the carburettor.

2. A mixture-forming device for multi-cylinder internal combustion engines, substantially as hereinbefore described with reference to the accompanying drawings.