GB2167127A

GB2167127A - Mixture-forming device for multicylinder internal combustion engines

Info

Publication number: GB2167127A
Application number: GB08524759A
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: GB8524759D0; FR2573485A1; IT8548549A0; IT1181733B

Abstract

Fuel from an electrically controlled metering valve 11 is discharged through respective outlets (14, Fig. 2) into the inlets 13 of branch pipes 8 leading to the manifold branches 4. At low engine outputs only the operator controlled valve 5 regulating air flow to a passage (7, Fig. 2) surrounding the valve 11 and to the pipes 8 is open, the valve 2 controlling air flow to the branches 4 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 for internal combustion engines.

A mixture-forming device is described in the German Offenlegungsschrift 29 51 788. This known device has a fuel-metering valve situated downstream of the throttle valve in a 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, there is known a central fuel injection device of a different kind. This device has spray-channels fed with fuel by an injection nozzle situated immediately upstream of a branching section of the air-induction channel.

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 fuel into the air-induction channel in a direction perpendicular to the axis of the channel, producing a jet pattern which distributes the fuel unevenly. 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.

The second of these known devices has the disadvantage that there are large inductionchannel wall surfaces, causing faulty response to torque changes in the engine, CO peaks and increased noxious substances in the exhaust gases.

The intention in the present invention, is to construct a mixture forming device in such a way that the combustible mixture is distributed precisely among the cylinders and so that the device responds promptly when engine-operating conditions change.

This invention provides a mixture-forming device for multicylinder 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 having a second air-induction channel containing a second throttle valve, this one actuated at will by the human operator of the engine; the second air-induction channel having a distributor passage and, branching out from this, mixtureinduction channels leading to the individual induction-manifold pipes; the two throttle valves being coupled together to act with parallelsequential timing; the device having a fuel metering valve situated in the second air-induction channel downstream of the second throttle valve, characterised in that the fuel metering valve is situated in the distributor passage of the second air-induction channel and has a group of jet-channels, each individual jet-channel being aimed at the mouth of one of the mixture-induction channels.

Advantages of the invention 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 sup piied 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.

Figure 1 is a diagramatic representation of an internal combustion engine equipped with a mixture-forming device of the invention.

Figure 2 is a section through the distributor passage, 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 first air-induction channel 3 there branch off individual cylinders of the engine. The mixture-forming device also has a second throttle valve 5 which is actuated at will by the operator of the engine.

The two throttle valves 2 and 5 are coupled together to open and close with a parallelsequential timing which will be described further below. From the second throttle valve 5 the second air-induction channel 6 leads to a distributor passage 7 (Fig. 2) and from here individual mixture-induction channels 8 lead out to the individual induction-manifold pipes 4. Upstream of the throttle valves 2, 5 the two air-induction channels 3, 6 are combined to form a common air-induction channel 9 equipped with a conventional air-flowmeter 10 (not shown) which need not be described in detail here. The air-flowmeter 10 provides information on the rate of flow of the aspirated air.

The distributor passage 7 of the second airinduction channel 6 contains a central electromagnetically actuated fuel metering valve 11 which is controlled, in dependence on aspirated air throughput and other engine and environmental parameters by an electronic con troller 12.

The fuel metering valve 11 has a group of jet-channels 14, each aimed to direct a jet of fuel under pressure towards the mouth 13 of a single mixture-induction 8. Thus each jetchannel 14 feeds a spray of fuel to its own mixture-induction channel 8.

Fig. 2 shows the distributor passage 7 of the second air-induction channel 6 in section, and also shows the mouths 13 of two of the mixture-induction channels 8.

The fuel metering valve 11 has a fuel chamber 15 which communicates through a fuelfeed channel 16 with the delivery side of a fuel pump (not shown).

A valve body 17, penetrating into the fuel chamber 15 controls the flow of fuel through the group of jet-channels 14, which are situated downstream of the seat 18 of the valve body 17, each individual jet-channel 14 being aimed at the mouth 13 of one of the mixtureinduction channels 8. Consequently when the valve body 17 lifts from its seat 18 fuel is sprayed into the mouth 13 of each individual mixture-induction channel 8. The high-speed current of air flowing through each mixtureinduction channel 8 from the second air-induction channel 6 picks up the spray of fuel and conveys it to the individual induction-manifold pipes 4 of one of the cylinders of the engine.

The same thing applies to the other jet-channels 14 of the group.

The fuel sprayed into the high-speed current of air entering each mixture-induction channel 8 is well atomised by the turbulence in the air. At high torques, with the first throttle valve 2 also open, the current of air in the induction-manifold pipes 4 is also travelling at high speeds and consequently the mixture is still further atomised and evaporated on entering the induction-manifold pipes 4.

The two throttle valves 2 and 5 are coupled together in such a way that during engine idling and at low engine torques only the second throttle valve 5 is open. With increasing torque both the throttle valves come open. Consequently, under all engine-operating conditions air travels at high speeds in the mixtureinduction channels 8. The first throttle valve 2 can be actuated either mechanically or pneumatically.

Claims

1. A mixture-forming device for multicylinder 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 having a second air-induction channel containing a second throttle valve, this one actuated at will by the human operator of the engine; the second air-induction channel having a distributor passage and, branching out from this, mixture-induction channels leading to the individual induction-manifold pipes; the two throttle valves being coupled together to act with parallel-sequential timing; the device having a fuel metering valve situated in the second air-induction channel downstream of the second throttle valve, characterised in that the fuel metering valve (11) is situated in the distributor passage (7) of the second airinduction channel (6) and has a group of jetchannels (14), each individual jet-channel being aimed at the mouth (13) of one of the mixture-induction channels (8).

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