GB2078307A

GB2078307A - I.C. engine fuel feed device

Info

Publication number: GB2078307A
Application number: GB8117874A
Authority: GB
Original assignee: Daimler Benz AG
Current assignee: Daimler Benz AG
Priority date: 1980-06-24
Filing date: 1981-06-11
Publication date: 1982-01-06
Also published as: SE449770B; IT1143406B; FR2485640B1; JPS6367025B2; FR2485640A1; JPS5732046A; DE3023506A1; DE3023506C2; IT8148650A0; SE8103933L; GB2078307B

Abstract

The device comprises a fuel valve having inlets 19, 20 for fuel and air respectively through which an additional quantity of fuel can be injected during a starting operation into air inlets e.g. 3, which lead to the engine cylinders, and includes an accumulator formed by a retaining wall 14 which holds back some of said additional quantity of fuel, the quantity held back flowing under gravitational force through a bypass 18. The retaining wall 14 and by-pass 18 are located in a part of the inlet which is formed in the idle speed air duct 6. <IMAGE>

Description

SPECIFICATION Fuel feed device for mixture-compressing internal combustion engines The invention relates to a fuel feed device for mixture-compressing internal combustion engines comprising a fuel valve through which an additional quantity of fuel can be injected during the starting operation into an air inlet manifold which leads to the cylinders of the internal combustion engine.

As is known, this type of fuel valve which is intended to assist the starting operation, is actuated in dependence upon the duration of operation of the engine starter motor with the aid of electrical switching means in the starter motor control circuit.

However, in order to prevent the cylinders from being flooded by an excess quantity of fuel in the event of long duration of starter operation, caused by faulty starting or non-starting of the engine, the control of the fuel valves is switched off after a predetermined interval by time-responsive and temperature-responsive switch elements.

If, however, it is only necessary to operate the starter for a short time as a result of relatively quick starting of the engine, then the quantity of fuel which is required for the continuous flow phase is absent from the intake system.

Drawbacks of this kind are overcome by additional electrical switching means in the fuel feed device, such as that disclosed in German Patent Specification No. 3 130 787. The additional electrical or electronic components are, however, exposed to special stresses or loads such as temperature and/or vibrations as a result of the operating conditions.

Long-term, trouble-free operation of the electrical components is difficult to achieve.

The present invention seeks to provide a simplified fuel feed device which does not have additional electrical or electronic components and which ensures an instantaneous starting of and trouble-free continuous flow through the internal combustion engine.

According to the present invention there is provided a fuel feed device for mixture-compressing internal combustion engines comprising a fuel valve through which an additional quantity of fuel can be injected during a starting operation of the engine into an air inlet which leads to the cylinder(s) of the internal combustion engine, wherein a fuel accumulator which is temporarily operative during the starting operation is provided in the air inlet manif old to retain part of said additional quantity of fuel.

On the one hand, the engine is started in this way during the starting operation by the additionally injected fuel (additional quantity for starting) and, on the other hand, some of the additional quantity is retained in the air inlet manifold in order that the intake air may continue to be enriched, although to a decreasing extent, after the fuel valve is switched off for the continuous flow phase, so that consequently a continuous flow through the internal combustion engine may be ensured.

Preferably, the fuel accumulator is formed by a retaining wall which holds back some of the additionally injected quantity of fuel and a by-pass is provided for the retained part of the additionally injected quantity of fuel.

A reservoir is formed in the air inlet manifold by the retaining wall so that, after the fuel valve is switched off, the quantity of fuel which has been accumulated during the starting operation mixes with the intake air behind the retaining wall via the by-pass.

In a preferred embodiment of the invention the retaining wall and the by-pass are located in a part of the air inlet manifold which is in the form of an idle speed air duct.

In order to ensure that the fuel flowing via the by-pass is sufficiently covered by the stream of intake air, the idling air duct may be such that the retained part of the additionally injected quantity of fuel flows, by virtue of gravitational force, through the by-pass into the idling air duct which, in the direction of flow, is situated behind the retaining wall.

As a result, the fuel which flows out via the by-pass by virtue of gravitational force can mix automatically with the intake air, thereby ensuring proper preparation.

In an advantageous embodiment of the invention the by-pass is located in the retaining wall, it being possible for the by-pass to be in the form of an outlet channel.

Preferably, the retaining wall is formed by a component part made of petrol-resistant plastics material, for example polyamide, which is fixed in the idling air duct. Such a measure constitutes a saving in cost and weight.

The invention will now be described in more detail by way of example with reference to the accompanying drawing in which: Figure 1 shows a device in accordance with the invention mounted in an inlet pipe flange of an internal combustion engine, Figure 2 shows the device of Figure 1 on an enlarged scale, Figure 3 shows the device in section, along the line Ill-Ill in Figure 2, Figure 4shows a retaining wall in elevation, and Figure 5shows the retaining wall in section, along the line V-V in Figure 4.

An inlet pipe flange 1 of a mixture-compressing internal combustion engine, as shown in Figure 1, contains air inlet manifolds, of which the inlet pipes leading to the cylinders of the internal combustion engine are designated by reference numerals 2,3,4 and 5 and idling air ducts which are situated in the inlet pipe flange 1 by reference numerals 6, 7, 8, 9, 10,11,12.

Branching from the idling air duct 6 to the left and right are the idling air ducts 7 and 8 and branching from the latter in turn are two further idling air ducts 9, 10 and 11, 12 which lead to the respective inlet pipes 2,3, 4, 5.

The central idling air duct 6 is partially closed by a retaining wall 14 in the direction of a flange sealing face 13.

This retaining wall 14 (Figures 4 and 5), which is in the form of sub-assembly component, is made of petrol-resistant plastics material, for example polyamide, has a cup-like shape and has at its upper section a flattened edge surface 15, and in addition in the lower section of the retaining wall 14 there is an opening 16, a rib 17 for reinforcement and an outlet channel 18 which, starting from the centre of the retaining wall 14, runs towards an outlet opening 16 leading to the idling air ducts 7, 8.

The central idling air duct 6 is of broader form in the area of the flange sealing face 13 and is correspondingly adapted to the cup-shaped retaining wall 14. A surface for attaching the retaining wall 14 is created by the broadening of the said duct.

Leading into the duct 6 is a fuel valve 19 which is used solelyforthe cold starting operation and through which an additional quantity of fuel can be injected. In addition to this fuel valve 18 there is provided an inlet 20 for intake air.

When fitted, the retaining wall 14, which has a cup-like shape, blocks, with its cylindrical wall 21,the idling air ducts 7 and 8. A duct recess 22 as shown in Figures 1 and 2 and the opening 16 in the retaining wall 14 permit the passage of the stream of intake air. A further passage of air occurs in the idling air duct 6 as a result of the flattened surface 15 of the retaining wall 14. The advantage of diverting the stream of intake air is described in more detail below.

During the starting operation the fuel valve 19 or cold start valve injects a quantity of fuel, which is intended solely for cold starting, into the idling air duct 6 which acts as a reservoir. Initially, part of this quantity of fuel is collected and retained by the retaining wall 14 whilst the other part of this quantity is entrained with the intake air through the opening in the idling air duct 6 which is formed by the flattened surface 15 of the retaining wall 14. The mixture thus prepared is diverted in the direction of flow behind the upper part ofthe retaining wail 14 as can be seen from Figure 3 - then passes through the opening 16 in the lower part of the retaining wall into the duct recess 22 and, from there, via the individual idling air ducts 7, 9, 10 and 8, 11, 12 into the inlet pipes 2, 3, 4, 5, which lead to the cylinders.

After starting, the quantity of fuel accumulated in the reservoir 6 will still flow out by virtue of gravitational force through the outlet channel which acts as a by-pass. The retained fuel mixes automatically with the intake air (high air velocity) and consequently, as a result of the special design of the idling air duct, ensures a mixture with good ignition qualities for the continuous flow phase which follows the starting phase.

As possible alternatives for fuel accumulation, there can be provided in the air inlet manifold, for example in the collecting inlet pipe or in the idling air duct, a grating consisting of wire mesh or an element acting as a sponge, both of which permit spontaneous starting and a continuous flow phase since the fuel which adheres to the grating or which is retained in the sponge-like element is removed by the air flow after the cold-start injection.

Claims

1. A fuel feed device for mixture-compressing internal combustion engines comprising a fuel valve through which an additional quantity of fuel can be injected during a starting operation of the engine into an air inlet which leads to the cylinder(s) of the internal combustion engine, wherein a fuel accumulator which is temporarily operative during the starting operation is provided in the air inlet manifold to retain part of said additional quantity of fuel.

2. A fuel feed device according to Claim 1, wherein the fuel accumulator is formed by a retaining wall which holds back some of said additional quantity of fuel, and a by-pass is provided for the retained part of the additional quantity of fuel.

3. Afuel feed device according to Claim 2, wherein the retaining wall and the by-pass are located in a part of the air inlet manifold which is in the form of an idle speed air duct.

4. A fuel feed device according to Claim 2 or 3, wherein the idle speed air duct is such that the retained part of the additional quantity of fuel flows, by virtue of gravitational force, through the by-pass into the idle speed air duct which, in the direction of flow, is situated behind the retaining wall.

5. A fuel feed device according to Claim 2,3 or 4, wherein the by-pass is located in the retaining wall.

6. A fuel feed device according to any one of Claims 2 to 5, wherein the by-pass is in the form of an outlet channel.

7. A fuel feed device according to any one of the preceding Claims, wherein the retaining wall is formed of petrol-resistant plastics material, which is located in the idle speed air duct.

8. A fuel feed device according to Claim 7 wherein the retaining wall is formed of polyamide.

9. A fuel feed device for a mixture-compressing internal combustion engine substantially as described herein with reference to and as illustrated in Figures 1 to 5 of the accompanying drawing.