DE2924498A1 - Fuel injection for multicylinder IC engine - has injection into pressurised chambers above cylinder air inlet pipes via short pipe with restricted cross=section - Google Patents

Abstract

The engine has an air intake (1) with a flowmeter (16) upstream of a throttle (2), which regulates the output of a fuel injection pump. From a manifold (3) downsteam of the throttle there are separate branches (4) to the individual cylinders. A branch (5) between the flowmeter and the throttle leads to a subsidiary manifold (6). This has outlets to a chamber (7) above each main branch (4) to a cylinder. Fuel is injected (F) into these chambers. There is a throttled orifice (9) from each chamber (7) into the inlet branch it serves. The orifice opening is determined by idling air flow and full load fuel flow requirements.

Description

Description of the patent application

Title: Injection system for gasoline engines with more than one cylinder Field of application: The invention relates to a gasoline engine with more than one Cylinder-specific injection system, especially for motor vehicle engines, which can also be operated without high fuel pressure.

Purpose: In gasoline engines with multiple cylinders, it is among other things required - that the ratio of fuel to air in the fuel-air mixture (called mixture) in the entire operating range with regard to engine power, fuel consumption and exhaust gas composition is optimally adhered to; - That the mixture is very uniform is distributed to individual cylinders; - That the suction paths (at full load) of the flowing Air have the lowest possible aerodynamic drag; - that at the transition (even with a fast one) from one operating state to another (e.g. with Transition from idling to partial or full load) no temporary "emaciation" or "Overfatting" of the mixture takes place.

In addition, the air-fuel supply system should be for regulation by using sensors that monitor the pollutant content in the exhaust gases, be well suited because in the foreseeable future the standard equipment of automobile engines can hardly be avoided with such control systems (since the environmental regulations are always tightened; in countries with extreme Even today, there are hardly any strict environmental regulations without such control systems to be observed). For the same reasons, the fuel-air supply system should be suitable for operation with exhaust gas recirculation.

It is also important that the fuel-air supply system be simple and is robust and that its maintenance in workshops without special equipment of personnel can be carried out with average training.

State of the art and It is known that in gasoline engines criticism of the State of the art with several cylinders in the carburettor: the mixture formed distributed unevenly to the individual cylinders to such an extent that this unevenness have a major impact on engine performance, fuel consumption and the composition of the exhaust gas affects.

If it were also possible to use the suction line with carburettor operation like this to design so that the mixture could be evenly distributed to individual cylinders, so could the air-fuel ratio by using a conventional carburetor (called air ratio) in the entire operating range hardly with a satisfactory approximation are adhered to within optimal limits, especially with different atmospheric Pressure and at different air temperatures.

Carburettors with a constant funnel cross-section also feed the suctioned Air has a high aerodynamic resistance, as a result of which the engine's performance is reduced.

Known injection systems are free from such disadvantages however, they are used relatively seldom because they are expensive, sensitive, and susceptible to failure and repair are. In addition, the maintenance and repair of injection systems can mostly only Carried out in workshops with special equipment by highly qualified personnel will.

Carburetors, on the other hand, are simple, robust; a repair on the carburetor is rarely required and can (as well as maintenance) in workshops with simpler Equipment to be carried out by personnel with average training.

Task: The invention is based on the task in an injection system to combine the advantages of an injection system and a carburetor to a high degree.

Solution According to the invention, this object is to be solved by the application the following dosing and injection principle can be solved (Fig. 1).

An air quantity measuring element (10), which according to the through the suction line (1) the amount of air flowing in the motor is moved against a restoring force, and a arbitrarily actuatable throttle valve (2) are in the intake line (1) in front of the Collective suction line (3) arranged downstream one behind the other.

The air quantity measuring element (10) used is one of those known in engine construction Devices: a volumetric flask (as in carburetors with variable funnel cross-section), or a flap, a baffle plate, a bellows or the like.

There is an air filter (not shown) at the inlet of the suction line (1) arranged.

The fuel is from the fuel metering device (8) into the Suction lines (4) injected into individual cylinders, but not directly (arrow F, Fig. 1), but first in chambers (7), in which the air pressure with a for the fuel metering required precision is regulated The latter is made possible that the chambers (7) with the Suction lines (4) individual cylinders are connected by short throttle lines (nozzles 9), whose the open cross-section is not larger than required for the air throughput when idling, but sufficiently large for the fuel throughput at full load, and that the cross-section the chambers (7) at the points (A-G) where the fuel is injected into these chambers and the cross-section of the air ducts connected to these chambers (5 and 6) is several times larger than the open cross-section of the nozzles (9). Through this becomes the level of pressure independence required for fuel metering at the injection points (A-G) in the chambers (7) from the pressure (negative pressure) in the suction lines (4) single cylinder guaranteed.

The chambers (7) are connected to one another by an air line (6), the air pressure in all chambers (7) is always the same.

The fuel enters from the chambers (7) through the nozzles (9) the intake manifolds (4) of individual cylinders. The one flowing through the nozzles (9) at the same time Air favors the atomization of the fuel The chambers (7) are through the air lines 5 and 6 on the section of the suction line (1) between the air flow meter (10) and Throttle valve (2) connected; the pressure in the chambers (7) equals one The precision required for fuel metering is the pressure in the intake line at the connection point of line 5 The difference between the pressure in the suction line (1) upstream directly in front of the air quantity measuring element (10) on the one hand and the pressure in the section of the suction line (1) at the connection point of the line 5 on the other hand changes depending on the air flow.

This pressure difference equals the pressure difference between the pressures in the suction line (1) upstream directly in front of the air quantity measuring element (10) on the one hand and the pressure in the chambers (7) on the other hand.

This (last-mentioned) pressure difference and the movement of the air flow meter (10) are used for fuel metering purposes.

Notes 1. Another way of using the one described Dosing and injection principle (injection through a chamber with adjustable air pressure) is the injection of the fuel at only one point (central injection) in the collecting suction line t3). The air manifold - intake pipe (1), manifold suction line (3) and intake manifolds (4) of individual cylinders - must for the purpose of even mixture distribution have a suitable shape on individual cylinders.

2. It is not absolutely necessary that the chambers (7) on the Suction line (1) in the section between the air flow meter (10) and the throttle valve (2) must be connected. You can move to another point of the air flow meter (10), to which the pressure changes depending on the air flow rate, must be connected, z. B. at the point with the smallest cross section (Fig. 2) on the air flow meter (10). Control valves can also be used for the purpose of regulating the pressure in the chambers (7) will. In individual cases, the pressure in the chambers (7) can be atmospheric pressure be kept the same. In the latter case, the chambers (7) can be used directly (apart from of filters) be connected to the atmosphere.

The fuel metering device (8) must functionally respond to the pressure changes (or constant pressure, if this is kept constant by regulating devices will) be matched in the chambers (7) according to the requirements of the engine.

3. The fuel is fed into the chamber (7) by the fuel metering device (8) in the direction of the nozzle (9) (arrow "F", Fig. 1).

Remarks 2 and 3 apply both to injection into the Intake pipes (4) for individual cylinders as well as for those mentioned in the first comment Central injection.

Embodiment (Fig. 2 to Fig. 5) Injection system with continuous Injection for a car gasoline engine with 4 cylinders (in-line engine) with the following Data: Displacement ...................................... 1800 cm3 Power ...... ............................... 73.6 kW (100 PS) fuel requirement - at maximum power .----- - Bmax = 26 kg / h = = 7.2 g / s - when idling ................. Bmin = 1.1 kg / h = = 0.3 g / s air requirement - at maximum output, mL max 320 kg / h = = 0.088 g / s - at idle - * mL min 13 kg / h = = 0.0038 g / s diameter of the nozzles (bores) 9 (Fig. 2, 3, 4 and 5) .... 1.4 mm The air quantity measuring element (10) is a volumetric flask (20), which through the pressure difference below and above the membrane 21 against the restoring force of the spring 22 is moved is used. The spaces below and above the membrane (21) are with the Suction line (1) upstream and downstream of the measuring piston (20) accordingly connected (pos. 28 and pos. 29, Fig. 2). The movements of the volumetric piston (20) are damped by a damper device (19). This measuring device is used in carburetor construction graze frequently; its function is known, so it is not detailed in FIG drawn and not described in detail here.

The chambers (7) through which the fuel enters the Sauo lines (4) Individual cylinder injected are through lines (5 and 6) to the Suction line (1) connected under the middle of the volumetric flask (20). Through the lines 6 the chambers are connected to each other.).

The fuel comes from a fuel tank (not shown) by a (not shown) fuel pump as in carburetor operation in two float chambers (25) promoted. The fuel pump here is the same as with carburettor operation.

The spaces above the fuel level of the float chambers (25) are through a ventilation line (26) with the suction line (q) upstream directly connected in front of the volumetric flask (20). The inlet (27) of the ventilation line (26) is directed against the air flow - the air pressure above the fuel level in the Float chambers (25) equal the total pressure in the suction line (1) on this Job.

Due to the effect of the air flow it is placed under the volumetric flask (20) and thus in the chambers (7) an air flow rate (and the position of the Measuring piston 20) dependent vacuum. Under the action of the pressure difference over the fuel level in the float chambers (25) on the one hand and in the chambers (7) on the other hand, the fuel enters the chambers through the lines (30) (7).

The fuel passes through the chambers (7) before it enters the fuel nozzles 23, the annular flow cross section (31) through the conical Part of the needles 24 enlarged or reduced (or kept constant) during their movements will. (The short cone at the lower end of the needle prevents the formation of drops.).

The needles (24) are fixed on the shaft 17 by means of joint pieces (partially drawn) levers (18) attached so that they are in the rotary movements the shaft (17) is lowered or be raised in such a way that the annular flow cross-sections (31) of the fuel nozzles (23) at all four injection points each stay the same.

The (symbolically drawn) mechanical connection (16, Fig 2) of the measuring piston (20) with the shaft (17, Fig. 3, Fig. 4 and Fig. 5) is the latter rotated so that the open cross-section under the measuring piston (20) on the one hand and the annular flow cross-sections (31) of the fuel nozzles (23) on the other hand change proportionally (apart from those required via the injection map Corrections). This results in a constant (apart from the mentioned corrections) Air / fuel ratio guaranteed.

For enriching the mixture during a cold start, warm-up and at full load the needles (24) are additionally acted upon in the mechanical connection (16, Fig. 2) raised.

In the suction pipe (1) is downstream in the vicinity of the measuring piston (20) a pitot tube (12) arranged. Through this pitot tube and further through lines (14 and 15) becomes the exit points of the nozzles (9) for the purpose of fuel atomization Air brought about. The total pressure at the entrance of the pitot tube (12) is with each The air throughput occurring here (through the suction line 1) is significantly higher than the (static) pressure at the outlet (11) of the air lines connected to the pitot tube (12), since the pitot tube (12) in the vicinity of the measuring piston (20) opposite the point with the smallest open cross-section is arranged under the volumetric flask.

To the air speed brought about by the pitot tube (12) Air to the outlet points of the nozzles (9) for the purpose of good fuel atomization increase, the exit points (11) of the air lines are tapered in their cross-section.

When idling, the air flow through the pitot tube (12) is through a additional throttle valve (13) throttled. This throttle (13) is idle by a (not shown) on the shaft of the throttle valve (2) arranged lever (stop) partially closed. The one required for idling Air flow is determined by changing the idle position of the additional throttle valve (13) set. The throttle valve (2), which can be operated at random, is idling closed as good as possible. Since idling downstream of the throttle (2) and thus at the exit points (11) connected to the pitot tube (12) If a relatively very high negative pressure is set in the air lines, the air flows through said exit points (11) even when idling at a very high speed. The energy of the air flow of the air flowing through these lines (based on a certain amount of fuel) is also idle for very good atomization of fuel is sufficient.

As already mentioned, the open cross-sections change under the Measuring piston (20) and the annular flow cross-sections (31) of the fuel nozzles (23) approximately proportional; The pressure differences also change approximately proportionally on the measuring piston (20) and on the fuel nozzles (23). As a result, that's changing Air / fuel ratio even with relatively large deviations in the measuring piston (20) insignificant from its theoretical position. (This is with known injection systems not the case). As a result, the injection system described is insensitive and robust - well suited for the "hostile to operations" conditions under the bonnet.

The amount of fuel injected is in the case of the injection system described does not depend on any distributors, equalization, control or injection valves. Therefore the distribution of the amount of fuel to individual cylinders is high and stable.

Each comparison of the injection system described with known ones Injection systems (also with the cheapest and easiest to maintain) shows that the manufacturing costs of the injection system described by a large margin lower and maintenance and repairs are much easier.

Claims (1)

Pater ispr che, to the patent application: Injection system for gasoline engines with more than one cylinder Generic term: to injection system (Fig. 1) for gasoline engines with more than one cylinder, in which there is an air quantity measuring element in the intake line (1) (10), which counteracts a restoring force corresponding to the amount of air flowing through is moved, and an arbitrarily actuatable throttle valve (2) arranged one behind the other are, and in which the fuel flows into the intake manifold (4) of individual cylinders the injection parts of a fuel metering device (8) is injected thereby characterized in that: Characteristic of each individual injection point is the part: Fuel from the injection part of the fuel metering device (8) not directly into the suction pipe (4) of the individual cylinder is injected, but first in a chamber (7), in which the air pressure with one for the fuel metering required precision is regulated, with that required for this purpose Degree of independence of the air pressure in the chamber (7) at the points (A-G) where the fuel is injected into the chamber (7, it is ensured that the chamber (7) with the suction line (4) of the individual cylinder through a nozzle (short Throttle line 9) is connected, whose flow cross-section (open cross-section) is not greater than required for the air throughput at idle, but sufficient great for fuel throughput at full load; is the cross-section of the chamber (7) at the point (A-G) where the fuel is injected into the chamber (7), several times larger than the cross section of the nozzles (9). * Otto engine = mixture-compressing externally ignited internal combustion engine ** Intake line - here: = air intake line Patertta½sprcii: e zur Patent application: Injection system for gasoline engines with more than one cylinder Applicant: Viktor Rosenau Sinnerstraße 10, 7500 Karlsruhe 21 Generic term 2. Injection system for gasoline engines with more of the secondary than one cylinder, in which the intake requirement: line OI an air quantity measuring element, which counteracts a restoring force accordingly the amount of air flowing through is moved, and an arbitrarily actuatable throttle valve are arranged one behind the other, and in which the fuel in the intake line at a point downstream of the throttle valve by the injection part of a fuel metering device is injected, characterized in that: Characteristic at the injection point the fuel con part: continuously from the injection part of the fuel metering device is not injected directly into the suction line, but first into a chamber, in which the air pressure with a precision required for fuel metering is regulated, with the necessary degree of independence of the Air pressure in the chamber at the point where the fuel is injected it is ensured that the chamber with the suction line at the injection point is connected by a nozzle (short throttle line) whose flow cross-section (open cross-section) is not larger than required for the air throughput at idle, but sufficiently large for the fuel throughput at full load; there is the Cross-section of the chamber at the point where the fuel is injected into this chamber is several times larger than the cross section of the nozzle. «Otto engine = mixture-compressing externally ignited internal combustion engine Intake line - here: = air intake line Claims, sheet 3 for patent application: Injection system for gasoline engines with more than one cylinder Applicant: Viktor Rosenau Sinnerstraße 10, 7500 Karlsruhe 21 Oberhegriff 3rd injection system according to claim 1 or 2 of the sub-characterized in that: claim: characterizing as a control component of the fuel metering part: device (8) one of the air throughput dependent pressure difference, which is caused by the action of the air flow meter (10) arises by connecting the chambers (7) or a chamber (7) to one of the pressure sides this pressure difference is used. Claims, sheet @ to the patent application: Injection system for Otto engines with more than one cylinder Generic term of the subclaim: 4. Injection system according to claim 1 or 2, characterized in that: Characteristic part: as a control component the fuel metering device (8) the adjustment of one or more adjustable, arranged in the fuel line throttle devices by the movement of the Air quantity measuring organ (10) is used. PatentareJsprLlcha, for patent application: Injection system for gasoline engines with more than one cylinder, generic term of the dependent claim: 5. Injection system according to claim 1 or 2, characterized in that: characterizing part: for the purpose a good atomization (misting) of the fuel at the exit point each Nozzle (9) air is brought about, which from the suction line (1) upstream the arbitrarily actuatable throttle valve (2) taken through lines (12, 14) will.