DE3514165C1 - Fuel pump, in particular diaphragm pump, driven by an internal combustion engine and attachable directly to it - Google Patents

Description

The invention relates to an engine driven by an internal combustion engine and attachable directly to it Fuel pump, in particular diaphragm pump, whose working chamber is filled and a suction valve Pressure valve is emptied.

These fuel pumps have proven themselves by their low Space requirements are excellent and are therefore often used for the fuel supply of the carburetor Internal combustion engines used that are used in motor vehicles.

Here, the fuel pump is attached directly to the motor housing and thus the variable, from the operating state exposed to the internal combustion engine dependent engine temperature. Considerable ones occur here Temperature differences, which are favored by the narrow engine compartments of the modern, streamlined bodywork will.

In connection with the recently noticeable increase in the low-boiling fuel content Driving errors in hot idling operation and hot start difficulties that arise as a result are often reported, that the fuel evaporates.

As can be seen from DE-OS 20 00 213, two types of disturbances generally occur, one is formed A vapor plug forms inside the pump and, on the other hand, a vapor plug forms in the pump with the mixture generator of the internal combustion engine connecting lines.

As a remedy is proposed in the aforementioned DE-OS 20 00 213, one with the pressure in this line A pressurized diaphragm must be provided, which in the event of a pressure increase caused by the formation of steam throttles the passage cross-section of the line leading to the mixture generator and at the same time a The return channel from this line opens into the suction line. A similar proposal is the DE-OS plugs in front of the pump can be removed.

This object is achieved with the features mentioned in the characterizing part of the patent claim. Advantage of the invention:

The fuel pump is in hot idle mode and during hot starts by the internal combustion engine Heat conduction and radiation extremely heated, so that the supplied from the fuel storage container Fuel evaporates as soon as it enters the pump. This has so far led to the fuel was pushed back into the suction line in the direction of the storage container by the fuel vapor and caused a longer time without fuel pumping until the onset of a liquid pumping, whereby Starting the engine or assuming a load from idling operation is difficult and even impossible became.

These errors no longer occur with the fuel pump according to the invention.

When the fuel enters the heated pump, the fuel evaporates in the antechamber a pressure rise, whereby the suction valve is closed and the pressure valve is opened and through the latter the fuel vapor is returned to the reservoir. When the pump s suction stroke again opens the suction valve and the pressure valve closes, so that again and directly cool fuel into the pump occurs and this cools down. It is obvious that the pump is cooled down as quickly as possible, so that short Start times, a good load assumption and also with a further increase in the low-boiling fuel proportions error-free hot operation is given.

An embodiment of the invention is shown in the drawing and is described below.

The fuel pump shown is designed as a diaphragm pump, but any other type of pump could be chosen without affecting the invention, and consists of a housing 1, a cover 2 and a membrane 3 clamped between housing 1 and cover 2, on which membrane plate 4 a plunger 5 is attached, which is loaded by a spring 6 and into an opening 7 of a motor housing 8 protrudes and there is in contact with a cam disk 9, the cam disk 9 on a Shaft 10 is arranged, which is driven by the motor shaft, not shown.

A working chamber 12 formed between a wall 11 of the cover 2 and the membrane 3 stands over Suction valve 13 with an antechamber 14 and a pressure valve 15 with a connection 16 for one to one not shown mixture former of the internal combustion engine leading line 17 in connection. The antechamber 14 is connected via a suction valve 18

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25 59 157 can be seen in which a pressure regulator is described, the in the line between pump 55 a suction port 19 and a pressure valve 20 with and mixture former regulates existing pressure and a return connection 21 in connection, both

Connections 19,21 via lines 22,23 to a not lead shown fuel storage container.

depending on a return channel controls over the fuel and possibly. Also fuel vapor in the Fuel reservoir can flow back.

The measures described in both publications thus serve to eliminate between pumps and mixture formers existing vapor plugs. However, no measures are indicated that can lead to Elimination of vapor plugs in front of the pump are suitable and which often lead to "the same" Driving and starting errors lead.

The object of the invention is therefore to design a generic fuel pump in such a way that steam is used for this purpose 1 sheet of drawings

Claims (1)

Claim: Fuel pump driven by an internal combustion engine and attachable directly to it, in particular Diaphragm pump, the working chamber of which is filled via a suction valve and a pressure valve emptied is, characterized in that upstream of the suction valve (13) an antechamber (14) is arranged, which via a further suction valve (18) and a pressure valve (20) via a suction and a Pressure connection (19, 21) is connected to the fuel storage container via lines (22, 23).