DE1068511B - Device for controlling the fuel supply in internal combustion engines - Google Patents

Description

The invention relates to fuel supply systems for engines in which the fuel is continuously injected into an intake duct which has a number of cylinders of one for example with spark ignition two- or four-stroke internal combustion engine. The amount of injected fuel must be varied according to the weight of the air per unit of time is introduced into the working cylinder of the engine. The weight of air by the engine per unit of time is introduced depends, among other things, directly on the speed of the engine.

In order to maintain a constant fuel-air ratio, the amount of fuel injected must be directly proportional to the weight of the air introduced.

Compared to the usual pneumatic control devices of internal combustion engines the invention from a device in which a special air pump (e.g. vacuum pump) is provided that - without as a supply source for the combustion air requirement of the internal combustion engine to serve - is driven by the latter and is designed in such a way that the generated by it Pressure difference (negative pressure) compared to atmospheric pressure in the ratio of the square of the engine speed changed, this pressure difference as a measured variable for regulating the fuel supply serves.

Control systems of this type must - ■ generally seen - be regarded as known, even if their application is used in internal combustion engines with manifold injection (for this application an independent Protection not sought) has not yet been immediately proposed. These control devices offer in a known way the possibility of designing the pressure chamber for generating the control pulses to be carried out as it is desired for the operation of the regulating organs. She works independently of pressure fluctuations in the inlet line caused by the working of the pistons and suction valves can be evoked, and there is the possibility of the area of the stimulating To make pressure differences greater than when using the intake manifold vacuum as the only one pneumatic measured variable.

Based on the application of this control device described in internal combustion engines with The invention recently provides for continuous intake manifold injection instead of separate drives for the air pump on the one hand and the fuel pump generating the injection pressure on the other hand to use a common drive mechanism for these two pumps, as is the case with fuel devices

for controlling the fuel supply in internal combustion engines

Applicant: Engineering

Research & Application Limited, Dunstable, Bedfordshire (Great Britain)

Representative: Dipl.-Ing. F. Weickmann

and Dr.-Ing. A. Weickmann, patent attorneys,

Munich 2, Brunnstr. 8/9

Claimed Priority: Great Britain April 28, 1955

Richard Henry Syson, Dunstable, Bedfordshire

(Great Britain), has been named as the inventor

Pump / windshield wiper vacuum pump combinations is known.

There is therefore no need to create dedicated drive devices for the air pump that provides the control pulse so that it is possible to use existing engine designs without difficulty to convert to working according to the invention injection devices.

An embodiment of the invention is illustrated below by means of an example on the basis of the schematic Drawing described, which shows an apparatus according to the invention partially in section.

The device consists of three main units, viz

1. a fuel pump / air pump unit 10,

2. a fuel measuring unit 11,

3. a fuel injection unit 12.

The unit 10 is assembled together on the machine for ease of installation. The two pumps are mounted in the same position and on the same flange as the well-known, mechanical fuel pump of a normal carburetor system. The injector takes its place in the inlet line below the throttle valve 16.

A normal fuel pump 17 is connected by the usual lever 18 and one by the engine.

909 647/114

driven eccentric 19 is actuated, fuel being passed from a tank 20 through a filter 21 and flows through a pipe 22. The lever 18 actuates an additional arm 23, plunger 24 and membrane 25 of a vacuum pump which has conventional valves, such as 26, and a return spring 27. These Pump evacuates air from a bell jar 28.

Air can be admitted into this bell jar through a nozzle created by a conical needle valve 29 is controlled. This nozzle sucks its air from the atmosphere through a hole 30, a Filter 31 with intake silencer on. The amount of air that flows through this nozzle is proportional the pressure difference between the atmosphere and the bell jar. Since the stroke of the diaphragm 25 is constant is, the volume of air pumped by 25 is also directly proportional to the speed of the Engine. This is why there is a pressure in the bell jar that changes as the square does the engine speed.

The needle valve 29 sits on a capsule 32, the interior of which is connected to the temperature measuring body via a tube 33 14 is connected in the inlet line.

The bell jar 28 is in communication with one side 36 of a membrane 34 through the line 37. The other side 35 of the membrane 34 is open to the atmosphere and is held by a spring 38. The membrane 34 interfaces with the membrane 40 of a second movable wall assembly a plunger 41 connected.

Fuel is fed to one side 47 of this assembly from tube 22 past a pressure relief valve 49 and a nozzle controlled by a needle valve 50. The membrane 40 is on their opposite sides exposed to the pressure differential created by a fuel nozzle, which is controlled by a second conical needle valve 42. The one flowing out of this nozzle Fuel enters a bore 43 which communicates at 44 with the other side 48 of the diaphragm 40. It is connected to the injection nozzle 12 via a connecting member 52 and the tube 53. The pressure relief valve 49 is connected to the tank 20 through the tube 54.

The pressure difference across 42 is proportional to the square of the amount of fuel that passes through the measuring nozzle 42 flows, or this amount of fuel is proportional to the expression:

difference then produces a flow through the measuring nozzle 42 which is proportional to the square root of N ² , ie proportional to N, the engine speed.

The pressure branch 13 goes from the inlet line 15 to a space 55, which is a pressure capsule 56 which regulates the position of the measuring needle 42. This pressure capsule consists of two sections above and below an intermediate wall 58, the larger portion closed all around and the

ίο Interior of the smaller section with a suction branch 57 is connected. This causes the increase in the absolute pressure in the inlet line 15, that the capsule shrinks and the main measuring needle 42 withdraws so that the The amount of fuel passing through the nozzle is increased.

In addition, it causes an increase in the back pressure of the exhaust, as it is connected to the inside via 57 of the small portion of the capsule communicates that this portion is expanding and thus the measuring needle 42 moves in the closing direction. In this way the amount of fuel flow depends on the absolute pressure in the inlet line 15 minus part of the exhaust back pressure.

The shape of the needle 29 is such that the amount of fuel flow is inversely proportional to the is the absolute temperature of the filling. The temperature control of the needle is such that an enlargement the filling temperature opens the needle valve and reduces the negative pressure on the vacuum bell jar. This decrease in pressure, in turn, reduces the amount of fuel flow through the mechanism, which has already been described above.

Claims (1)

PATENT CLAIM: P _{1 is} the absolute fuel pressure on the inflow side of the measuring nozzle 42, while P _{2 is} the absolute fuel pressure on the outflow side of the nozzle. The negative pressure generated in the bell jar and communicating with the side 36 of the membrane 34 urges the needle valve 50 toward the open position. The opening of the needle valve causes the pressure of the fuel pump is brought into communication with the measuring nozzle 42, whereby the flow enlarged through this nozzle until the membranes 40 and 34 come into equilibrium. The vacuum in the bell jar is proportional to N ² . When the needle valve 50 is in equilibrium, the pressure differential on either side of the diaphragm 40 is also proportional to N ^2. This pressure device for continuous pressure atomization of fuel into the inlet line of an internal combustion engine with a mechanically driven fuel pump and with regulation of the amount of fuel injected depending on the speed of the machine, characterized by a special air pump (e.g. vacuum pump 10), which - without as a supply source for to serve the combustion air requirement of the machine - is driven by the latter and is designed in such a way that the pressure difference (negative pressure) generated by it changes in relation to atmospheric pressure in the ratio or at least approximately in the ratio of the square of the engine speed, this pressure difference being a measured variable for the Control of the fuel supply is used, and further characterized in that the drive provided between the internal combustion engine on the one hand and the air pump (10) and the injection pump (17) on the other hand by means of a drive element common to both pumps (e.g. S. rocking lever 18) takes place.
60 Documents considered: German Patent No. 712 708; German patent application K 17486 I a / 46b ² (published April 14, 1955); British Patent Nos. 402 526, 560196, 577 560, 681346;
U.S. Patent Nos. 2,446,339, 2,570,560. 1 sheet of drawings