GB2112065A - An i.c. engine fuel injection valve filter arrangement - Google Patents

Abstract

Faces of valve body elements 4 and 5 bearing against the filter disc 14 have annular grooves 11 and 12 forming part of the fuel path to the valve outlet and the openings 15 in the disc have a diameter of 0.13 mm with a centre to centre spacing of 0.7 mm. <IMAGE>

Description

SPECIFICATION An injection valve for an internal combustion engine The invention relates to an injection valve, comprising a fuel filter, for an internal combustion engine.

German Auslegeschrift No. 10 36 576 discloses a known fuel filter, in an injection valve, which is intended to prevent clogging caused by impurities or contaminants in the nozzle region of the injection valve.

This filter consists of two disc-like components arranged concentrically with each other, surfaces directed towards each other and stepped faces opposite to annular grooves forming filtration passages.

With such filters, the nozzle region remains largely free from impurities because, due to the labyrinthine disposition, metal chips settle in the filtration passages. However, deposits in the said passages lead to clogging and to impairment of function of injection valves.

The present invention seeks to provide a simple filter construction in injection valves, whereby long-term trouble-free injection operation can be achieved. In addition, it is to be possible so to refit conventional injection valves which do not yet have a fuel filter that only slight valve modifications are required.

According to the invention, in an injection valve for an internal combustion engine, comprising valve elements which are clamped against one another by a nozzle lock nut and which have inlet bores leading to the injection needle, and a discshaped fuel filter between two valve elements whose faces bearing against the fuel filter have annular grooves which are connected to the inlet bores, the filter is in the form of a sieve plate whose sieve openings have a diameter of less than 0.15 mm.

With the fuel filter according to the invention, metal chips are comminuted to such an extent upstream of the small openings of the screening plate as a result of pressure surges in the injection system until the chips are entrained through the openings with the flow. The comminuted metal chips reach the nozzle outlet without being obstructed because all passage cross-sections downstream from the fuel filter are larger than the diameters of the openings. Trouble-free long operation of the injection valve is ensured.

An embodiment of the invention by way of example will now be more fully described by reference to the accompanying drawings, in which: Fig. 1 is a longitudinal section through an injection valve with a fuel filter, Fig. 2 is a partial section to a larger scale of an injection valve, according to the invention, with a disc-shaped sieve plate, and Fig. 3 is a partial section of the injection nozzle of the valve to a larger scale.

The valve 1 shown in Fig. 1 consists substantially of an upper nozzle-holder 2, an intermediate section 3 and a lower, injection, nozzle 4 comprising a nozzle body 5 and an injection needle 6. The nozzle 4, the intermediate section 3 and the holder 2 are secured together by a nozzle-locking nut 7. The fuel is supplied via an inlet passage 8 in the holder 2 and an annular groove 9 in the intermediate section 3 and via inlet openings and a further annular groove 11 in the intermediate section 3. Finally, through an annular groove 12 in the nozzle 4 and an inlet opening 13 which leads from the said annular groove, the fuel is delivered to the injection needle 6.

Between the intermediate section 3 and nozzle body 5, as shown in Figs. 1 and 2, there is, as an intermediate layer or shim, a fuel filter 14 which covers the annular grooves 11 and 12 and is formed by a disc-shaped sieve plate with small perforations 1 5. The diameters of the perforations are, for example, 0.13 mm and the spacing between perforations, from centre to centre, is, for example, 0.7 mm. Such a plate can be manufactured cheaply by boring methods based on galvanic, electro-erosion or laser action.

The spring-loaded injection needle 6, which is lifted from its valve seating in the direction opposite to the direction of flow of the fuel, is provided, as can be seen from Fig. 3, with a cross bore 1 6 and, branching therefrom, a longitudinal bore 1 7. With known valve constructions which are equipped in the holder 2 with a rod filter in the form of a gap filter, it may happen that a metal chip 1 8 settles in the longitudinal bore 17 of the needle 6 and thus blocks fuel flow through the nozzle (Fig. 3).

Metal chips which are forced through the small perforations do not have an adverse influence on the injection operation of the injection valve.

Because of their size, these chips do not remain fixed in bores of the injection needle stem or in spray holes located in the nozzle body.

The sieve plate can be used anywhere where small spray holes are to be protected in the injection valve.

1. An injection valve for an internal combustion engine, comprising valve elements which are clamped against one another by a nozzle lock nut and which have inlet bores leading to the injection needle, and a disc-shaped fuel filter between two valve elements, whose faces bearing against the fuel filter have annular grooves which are connected to the inlet bores, wherein the fuel filter is in the form of a sieve plate whose sieve openings have a diameter of less than 0.15 mm.

2. An injection valve, for an internal combustion engine, substantially as hereinbefore described with reference to the accompanying drawings.

**WARNING** end of DESC field may overlap start of CLMS **.

Claims (2)

**WARNING** start of CLMS field may overlap end of DESC **. SPECIFICATION An injection valve for an internal combustion engine The invention relates to an injection valve, comprising a fuel filter, for an internal combustion engine. German Auslegeschrift No. 10 36 576 discloses a known fuel filter, in an injection valve, which is intended to prevent clogging caused by impurities or contaminants in the nozzle region of the injection valve. This filter consists of two disc-like components arranged concentrically with each other, surfaces directed towards each other and stepped faces opposite to annular grooves forming filtration passages. With such filters, the nozzle region remains largely free from impurities because, due to the labyrinthine disposition, metal chips settle in the filtration passages. However, deposits in the said passages lead to clogging and to impairment of function of injection valves. The present invention seeks to provide a simple filter construction in injection valves, whereby long-term trouble-free injection operation can be achieved. In addition, it is to be possible so to refit conventional injection valves which do not yet have a fuel filter that only slight valve modifications are required. According to the invention, in an injection valve for an internal combustion engine, comprising valve elements which are clamped against one another by a nozzle lock nut and which have inlet bores leading to the injection needle, and a discshaped fuel filter between two valve elements whose faces bearing against the fuel filter have annular grooves which are connected to the inlet bores, the filter is in the form of a sieve plate whose sieve openings have a diameter of less than 0.15 mm. With the fuel filter according to the invention, metal chips are comminuted to such an extent upstream of the small openings of the screening plate as a result of pressure surges in the injection system until the chips are entrained through the openings with the flow. The comminuted metal chips reach the nozzle outlet without being obstructed because all passage cross-sections downstream from the fuel filter are larger than the diameters of the openings. Trouble-free long operation of the injection valve is ensured. An embodiment of the invention by way of example will now be more fully described by reference to the accompanying drawings, in which: Fig. 1 is a longitudinal section through an injection valve with a fuel filter, Fig. 2 is a partial section to a larger scale of an injection valve, according to the invention, with a disc-shaped sieve plate, and Fig. 3 is a partial section of the injection nozzle of the valve to a larger scale. The valve 1 shown in Fig. 1 consists substantially of an upper nozzle-holder 2, an intermediate section 3 and a lower, injection, nozzle 4 comprising a nozzle body 5 and an injection needle 6. The nozzle 4, the intermediate section 3 and the holder 2 are secured together by a nozzle-locking nut 7. The fuel is supplied via an inlet passage 8 in the holder 2 and an annular groove 9 in the intermediate section 3 and via inlet openings and a further annular groove 11 in the intermediate section 3. Finally, through an annular groove 12 in the nozzle 4 and an inlet opening 13 which leads from the said annular groove, the fuel is delivered to the injection needle 6. Between the intermediate section 3 and nozzle body 5, as shown in Figs. 1 and 2, there is, as an intermediate layer or shim, a fuel filter 14 which covers the annular grooves 11 and 12 and is formed by a disc-shaped sieve plate with small perforations 1 5. The diameters of the perforations are, for example, 0.13 mm and the spacing between perforations, from centre to centre, is, for example, 0.7 mm. Such a plate can be manufactured cheaply by boring methods based on galvanic, electro-erosion or laser action. The spring-loaded injection needle 6, which is lifted from its valve seating in the direction opposite to the direction of flow of the fuel, is provided, as can be seen from Fig. 3, with a cross bore 1 6 and, branching therefrom, a longitudinal bore 1 7. With known valve constructions which are equipped in the holder 2 with a rod filter in the form of a gap filter, it may happen that a metal chip 1 8 settles in the longitudinal bore 17 of the needle 6 and thus blocks fuel flow through the nozzle (Fig. 3). Metal chips which are forced through the small perforations do not have an adverse influence on the injection operation of the injection valve. Because of their size, these chips do not remain fixed in bores of the injection needle stem or in spray holes located in the nozzle body. The sieve plate can be used anywhere where small spray holes are to be protected in the injection valve. CLAIMS

1. An injection valve for an internal combustion engine, comprising valve elements which are clamped against one another by a nozzle lock nut and which have inlet bores leading to the injection needle, and a disc-shaped fuel filter between two valve elements, whose faces bearing against the fuel filter have annular grooves which are connected to the inlet bores, wherein the fuel filter is in the form of a sieve plate whose sieve openings have a diameter of less than 0.15 mm.

2. An injection valve, for an internal combustion engine, substantially as hereinbefore described with reference to the accompanying drawings.