AT9230U1 - INJECTION DEVICE - Google Patents

Abstract

The invention relates to an injection device (1) for an internal combustion engine fueled with liquefied petroleum gas, with a valve needle (10) loaded in the closing direction by a return spring (11), which is designed to be opened by fuel, with at least one fuel channel (4) having housing (2) in which an opening in the direction of injection spring-loaded check valve (5) is arranged. In order to enable high injection rates at low injection pressures, it is provided that the valve needle (10) is designed to open outwards and preferably has a valve disk (13).

Description

2 AT 009 230 U1

The invention relates to an injection device for an internal combustion engine fueled with liquefied petroleum gas, with a valve needle loaded in the closing direction by a return spring, which is designed to be opened by fuel, with a housing having at least one fuel passage in which an opening in the direction of injection spring-loaded check valve is arranged.

Liquefied gas, especially DME (DiMethyl Ether), is considered to be an alternative fuel for auto-ignition internal combustion engines with direct injection of the fuel into the combustion chamber to produce particularly low emissions of NOx and particulates. The problem, however, is that it comes due to the low viscosity of LPG fuels after shutdown to internal leaks in the combustion chamber. These leaks are a safety hazard and can cause damage to the engine.

US Pat. No. 6,189,517 B1 discloses an injection device for liquefied petroleum gas which has an inwardly opening valve needle. By arranged in the fuel passage check valve leaks are effectively avoided. The check valve blocks the passage cross section of the fuel passage as soon as the fuel pressure drops below a predefined level, ie as soon as the internal combustion engine is switched off. This keeps a residual pressure in the system, which makes it possible to keep the fuel liquid. The disadvantage is that inwardly opening valve needles allow only a small injection hole cross-section and that the geometric and the strength limits are limited, whereby an increase of the injection pressure limits are set.

It is known per se from EP 0 246 220 A1 to use an injection device with a poppet valve in diesel internal combustion engines. However, injectors of the poppet valve design have the disadvantage in the case of diesel fuel that deposits arise in the area of the poppet valve, which leads to leaks.

The object of the invention is to avoid these disadvantages and to allow higher injection rates and at the same time to avoid leaks in the combustion chamber after switching off the internal combustion engine.

According to the invention this is achieved in that the valve needle is designed to open outwards and preferably has a valve disk.

Trained as a poppet valve needle allows a larger injection cross-section, whereby larger amounts of fuel can be injected in less time. This has an advantageous effect on the combustion process.

Furthermore, the use of a valve needle with a valve disk has the advantage that the injection cross section is not limited by the number and size of nozzle bores. Thus, significantly higher flow rates can be effected at lower injection pressures. The umbrella-like jet shape favors the distribution of fuel in the combustion chamber.

Since LPG fuels burn with no soot deposits, there are no deposits in the area of the valve disk.

The invention will be explained in more detail below.

1 shows an injection device according to the invention in a longitudinal section when the valve needle is closed, and FIG. 2 shows the injection device when the valve needle is open.

The figures show an injection device 1 for liquefied petroleum gas with a housing 2 in which a fuel channel 4 emanating from a connection 3 is arranged. In the fuel passage 4, a check valve 5 is provided. The return opening in the direction of injection

Claims (1)

3 AT 009 230 U1 stop valve 5 has a ball 6 loaded by a spring 6, wherein the spring 6 acts on the ball 7 via a piston 8. The ball 7 is pressed against a valve seat 9. In the housing 2, an outwardly opening valve needle 10 is further arranged with a valve plate 13, which is held by a closing spring 11 in a closed position. The KraftstoffkanaI 4 opens into the spring chamber 12 and acts on the valve needle 10 against the force of the return spring 11 a. The injection device 1 differs from a conventional diesel injection device in that the valve needle is designed to open outward and has a valve disk 13. In the idle state, the valve needle 10 and the check valve 5 is closed. When the pressure in the injector 1 exceeds a value defined by the valve seat 9 and the spring 6, the check valve 5 opens, causing the LPG fuel to enter the spring chamber 12 under pressure. The check valve 5 remains open during the normal running of the internal combustion engine, since the closing pressure is much lower than the opening pressure. As soon as the internal combustion engine is stopped, the fuel pressure also falls below the closing pressure of the check valve 5, whereby the amount of leakage reaching the combustion chamber is the maximum amount of liquid remaining between the check valve 5 and the valve disk 13 of the valve needle 10. During two injections, the pressure in the spring chamber 12 is too low to cause an opening of the valve needle 10. However, when the fuel pressure rises sufficiently, the valve needle 10 is opened and fuel may enter the combustion chamber. Claim: Injection device (1) for an internal combustion engine fueled with liquefied petroleum gas, with a valve needle (10) loaded in the closing direction by a return spring (11), which is designed to be opened by fuel, with at least one fuel channel (4 ), in which a spring-loaded check valve (5) opening in the injection direction is arranged, characterized in that the valve needle (10) is designed to open outwardly and preferably has a valve disk (13). For this purpose 1 sheet of drawings