GB2172658A

GB2172658A - A fuel injection system for an internal-combustion engine

Info

Publication number: GB2172658A
Application number: GB08606916A
Authority: GB
Inventors: Dietrich Tegtmeier
Original assignee: Daimler Benz AG
Current assignee: Daimler Benz AG
Priority date: 1985-03-21
Filing date: 1986-03-20
Publication date: 1986-09-24
Also published as: DE3510226C2; GB8606916D0; DE3510226A1; IT8647786A0; FR2579271A1; GB2172658B; IT1191295B; FR2579271B1; JPS61223268A

Abstract

A single intake pipe 1 per cylinder includes a web wall 4, by which the single intake pipe 1 is subdivided into two separate intake pipe sections 2, 3 leading to two inlet ports in the cylinder. Upstream of the web wall 4, an injection nozzle 10 is arranged in the single intake pipe 1. A further injection nozzle 6 is arranged in the region of the web wall 4 and fuel is injected therefrom in idling and part-load operation into a mixing chamber 8 lying within the web well. From the mixing chamber 8, the fuel exits into both intake pipe sections 2, 3. The quantity of fuel required for the upper part-load and full-load ranges is achieve by switching in the first injection nozzle. <IMAGE>

Description

SPECIFICATION A fuel injection system for an internal-combustion engine The invention relates to a fuel injection system for an internal-combustion engine with two inlet ports for each cylinder, with a single intake pipe per cylinder, which pipe encompasses both inlet ports and is subdivided by means of a web wall into two separate intake pipe sections each leading to a respective one of the inlet ports, with a manifold intake pipe receiving the individual intake pipes, and with two injection nozzles in each single intake pipe.

From German Offenlegungsschrift 2,414,022, a fuel supply system for an applied-ignition internal-combustion engine with two fuel inlet valves per cylinder is known.

From the intake pipe of the internal-combustion engine, single intake pipes, in each of which is arranged a fuel valve, lead to each of the gas inlet valves. In this arrangement, for each cylinder there is a first gas inlet valve assigned to the main combustion chamber and a second gas inlet valve assigned to a secondary combustion chamber, which is in connection with the main combustion chamber by a flame port. Arranged in the secondary chamber is a spark plug, with which the constantly rich fuel/air mixture is ignited. The flame front directed through the flame port from the secondary combustion chamber to the main combustion chamber is used to ignite. the fuel/air mixture there, which is adapted to the changing operating conditions of the internal-combustione engine.However, a disadvantage of this arrangement is that, on account of the low flow velocity of the intake air in the single intake pipe and the remote arrangement of the fuel valve from the gas flow control valve, in the upper load and lower speed ranges the fuel/air mixture is not mixed thoroughly enough, which results in speed variations and unsatisfactory emissions.

From the periodical mot 11/84, an internalcombustion engine with injection system is known, in which two separate inlet ports, for each cylinder, are combined in a single intake pipe per cylinder. A web wall arranged in the region of the cylinder head in the single intake pipe subdivides the single intake pipe into two separate intake pipe sections. Arranged upstream of the web wall in the single intake pipe is an injection nozzle. Owing to the arrangement of the injection nozzle, the internalcombustion engine does not have a satisfactory responsive behaviour in non-steady-state operation and subsequent exhaust treatment is hampered.

Furthermore, from British Patent Specification 1,351,771, an intake system for an internal-combustion engine is known, which includes a manifold intake pipe from which single intake pipes lead to the inlet valves of the cylinder. Arranged upstream of the gas flow control valves inthe single intake pipes are fuel injection nozzles. In the manifold intake pipe there is a multi-hole fuel nozzle for the fuel supply during idling operation. Disadvantages are the poor response behaviour of the internal-combustion engine to load cycles and poor running in the lower speed range, which are attributable to the remote position of the multi-hole fuel nozzle from the gas-reversing valve and its arrangement in the manifold intake pipe.During idling operation, the air speed in the manifold intake pipe is too low to generate adequate turbulence for mixing the fuel/air mixture in the combustion chamber.

The present invention seeks to ensure a constantly good, thorough mixing of the fue I/air mixture in the intake pipe even in the lower load and upper speed ranges of the internal-combustion engine.

According to the invention there is provided a fuel injection system for an internal-combustion engine with two inlet ports for each cylinder, with a single intake pipe per cylinder, which pipe encompasses both inlet ports and is subdivided by means of a web wall into two separate intake pipe sections each leading to a respective one of the inlet ports, with a manifold intake pipe receiving the individual intake pipes, and with two injection nozzles in each single intake pipe, wherein a first one of the injection nozzles is arranged in the region of the web wall, from which fuel is injected in idling and part-load operation into a mixing chamber lying within the web wall and exits from this mixing chamber into both intake pipe sections, and the second injection nozzle is arranged upstream of the web wall and is adapted to be switched in for the quantity of fuel required in the upper part-load and fullload ranges of the engine.

Preferably, an idle air port opens out into the mixing chamber and is led through the web wall to an inlet on the exterior of the intake pipe. In this case, in the installed position, the idler air port inlet may be located on the underside of the intake pipe.

Preferably, shot ports through which fuel from the mixing chamber enters the intake pipe sections are arranged in continuation of the mid-longitudinal axis of the first injection nozzle and are angularly inclined with respect to each other.

The injection system according to the invention has the advantage that the fuel nozzle lying close to the gas flow control valve for idling and part-load operation is an idle air port in which the intake air reaches a high speed, whereby a good, thorough mixing of the fuel/air mixture in the cylinder is ensured and a reduction of the emission in idling operation is achieved. On account of the intensive flow of intake air around the fuel injection nozzle, no fuel residues are left behind on the fuel injection nozzle or in mixing chamber. The fue I/air mixture for idling operation is thus uniformly homogenous, thereby stabilizing the idling speed so that it can be adjusted to a low speed.

An embodiment of the invention is illustrated in the drawing, in which Figure 1 shows, in mid-longitudinal section, a single intake pipe of an injection system of an internal-combustion engine, Figure 2 shows the single intake pipe in accordance with the section profile ll-ll from Fig. 1, Figure 3 shows the reception area of the fuel injection nozzle according to the section profile Ill-Ill from Fig. 1.

In Fig. 1, 1 denotes a single intake pipe of an intake system, not shown in more detail, on an internal combustion engine with four gas flow control valves per cylinder, which pipe is attached at the cylinder head in continuation of the gas flow ports. Arranged upstream of the mouth of the single intake pipe 1, in the direction of the axial extension of the single intake pipe 1, is a web wall 4, which subdivides the single intake pipe 1 into a lefthand and a right-hand single intake pipe region 2, 3. The web wall 4 extends in axial direction up to approximately the centre of the single intake pipe 1. Provided in the vicinity of the mouth of the single intake pipe 1 in the web wall 4 is a reception area 5 for a first, indicated fuel injection nozzle 6.The mid-longitudinal axis 7 of the first fuel injection nozzle 6 points in the direction of the gas flow control valve, (inlet valve) not shown. Shot ports 13, 14 arranged in the web wall 4 are arranged in continuation ofthe mid-longitudinal axis 7 and connect the left-hand and righthand regions 2, 3 of the single intake pipe to a mixing chamber 8 which is formed ahead of the first fuel nozzle 6 by-the shot channels 13, 14 and in which an idle air port 9 led through the web wall 4 opens out. The shot ports 13, 14 open out into the intake pipe sections 2, 3 directly in the region of theparting joint between the cylinder head and the single intake pipe 1 in the region of the latter's mid-longitudinal axis 17. The idle air port 9 penetrates the bounding wall of the single intake pipe 1 on the side of the single intake pipe 1 opposite the fuel injection nozzle 6.The idler air port 9 is dimensioned such that, in an internal-combustion engine with a power of 136 kW and a swept volume of 2299 cm3, the air flow through the port into the chamber 8 reaches a speed of about 120 m/s, so that a mass flow of about 14kg/h is feasible. Provided upstream of the web wall 4 is a receptable 10 for a second fuel injection nozzle 11, shown in indicated form, which can be switched in during full-load operation. The mid-longitudinal axis 12 of the fuel injection nozzle 11 likewise points in the direction of the gas flow control valve, not shown.

The single intake pipe 1 illustrated in Fig. 2 in mid-longitudinal section according to the section profile ll-ll from Fig. 1 is subdivided by the web wall 4 into a left-hand and a righthand single intake pipe region 2, 3. Arranged in the web wall 4 is the idle port 9, which penetrates the bounding wall of the single intake pipe 1 on the opposite side of the fuel injection nozzle 6.

The reception region 5 of the first fuel injection nozzle 6 is illustrated in Fig. 3 according to the section profile Ill-Ill from Fig. 1. The single intake pipe 1 is subdivided by the web wall 4 into the left-hand and the right-hand single intake pipe regions 2, 3. The shot ports 13, 14 having an identical cross-sectional area connect the left-hand and right-hand single intake pipe regions 2, 3 to the fuel injection nozzle 6 and form, upstream of the latter, a mixing chamber 8 in which the idle air port 9 also opens out. The axes 15, 16 of the shot ports 13, 14 intersecting with the mid-longitudinal axis 7 are arranged in V shape with respect to each other at an angle of taper a which is equal to or less than the angle of taper which is assumed by the fuel when emerging from the fuel injection nozzle 6.

In a further embodiment of the invention which is not shown, the idle air port can also be arranged in the region of the fuel injection nozzle, intake air flowing around the end region of the fuel injection nozzle facing the intake air.

Claims

1. A fuel injection system for an internalcombustion engine with two inlet ports for each cylinder, with a single intake pipe per cylinder, which pipe encompasses both inlet ports and is subdivided by means of a web wall into two separate intake pipe sections each leading to a respective one of the inlet ports, with a manifold intake pipe receiving the individual intake pipes, and with two injection nozzles in each single intake pipe, wherein a first one of the injection nozzles is arranged in the region of the web wall, from which fuel is injected in idling and part-load operation into a mixing chamber lying within the web wall and exits from this mixing chamber into both intake pipe sections, and the second injection nozzle is arranged up-stream of the web wall and is adapted to be switched in for the quantity of fuel required in the upper part-load and full-load ranges of the engine.

2. An injection system according to claim 1, wherein an idler air port opens out into the mixing chamber and is led through the web well to an inlet on the exterior of the intake pipe.

3. An injection system according to claim 2 wherein in the installed position the idler air port inlet is located on the underside of the intake pipe.

4. An injection system according to claim 1, 2 or 3 wherein shot ports through which fuel from the mixing chamber enters the intake pipe sections are arranged in continuation of the mid-longitudinal axis of the first injection nozzle and are angularly inclined with respect to each other.

5. An injection system for an internal combustion engine substantially as described herein with reference to and as illustrated in the accompanying drawings.