GB2083861A - Fuel injector for I.C. engines - Google Patents

Abstract

The injector comprises a differential needle (2) and a body (5) defining a closed cylindrical space (53) situated above the needle and accommodating a prestressed spring (7). The axis (531) of the space (53) is spaced from and parallel to the axis (21) of the needle and a cylindrical member (8) is situated in the space between the spring and the upper end of the needle and guided slidably by the wall of the space. The pressure of fuel in the space (53) assists seating of the needle (2) by the spring (7). <IMAGE>

Description

SPECIFICATION An injector for combustion engines The invention relates to an injector for combustion engines, the injector having a closed hole-injection nozzle, or a pin-injection nozzle, and being provided with a differential needle opened both by the pressure of injected fuel towards the injector against a prestressed spring situated in a closed cylindrical space, and by pressure of fuel filling the closed cylindrical space above the differential needle.

In known designs of injectors for combustion engines, the closed cylindrical space above the differential needle of the injection nozzle is coaxial with the axis of the differential needle. A longitudinal channel is bored in the body of the injector along the closed cylindrical space.

Through the said channel the delivered fuel is supplied to the injection nozzle. In this case the radial dimensions of the injector are relatively large, which is disadvantageous for modern engines.

The aim of the invention is to devise an injector for combustion engines, the radial dimensions of which are as small as possible.

The said aim is achieved by the invention in that the axis of the closed cylindrical space above the differential needle in the injection nozzle is spaced from and parallel to the axis of the differential needle, and between a spring seated in the closed cylindrical space and upper end of the differential needle is situated a cylindrical guide, guided slidably by a wall of the closed cylindrical space.

In order that the invention may be clearly understood and radially carried into effect, a preferred embodiment thereof is, by way of example, hereinafter more fully described and illustrated in the accompanying diagrammatic drawing which shows a longitudinal section of the injector.

An injection nozzle, comprising a body 1 and in it a lapped differential needle 2, is fixed to the lower face of the body 5 of the injector, through an insert 4, by means of a cup nut 3. In the body 5 of the injector is formed a closed cylindrical space 53 extending from its lower face. The axis 531 of the space 53 is parallel to the axis 21 of the needle 2, the two axes 21, 531 being spaced from each other by a distance e. A prestressed spring 7 is situated in the space 53. The upper end of the spring 7 bears onto an exchangeable insert 9, and its lower end onto a cylindrical guide 8, against the lower face of which bears the upper reduced end of the needle 2 passing freely through a central bore in the insert 4, the latter being also provided with a channel 41.

The mutual position of the body 5 of the injector, of the insert 4 and of the body 1 of the injection nozzle is secured by at least one pin 6. A longitudinal channel 52 is bored in the body 5 of the injector from its lower face along the space 53. The said longitudinal channel 52 communicates in the upper part with an inclined channel 51 which in turn communicates with a bore 54, to which the outlet end of delivery piping (not shown) is connected.

A pin 10 is used to ensure the desired position of the body 5 of the injector in the head (not shown) of the engine, which is pressed radially into the upper part of the body 5 of the injector.

Fuel supplied into the channel 51 passes through the longitudinal channel 52 in the body 5 of the injector and through the channel 41 in the insert 4 into the channel 11 in the body 1 of the injection nozzle and to its seat, closed by the lower end of the needle 2. As soon as the pressure of the delivered fuel, acting from below onto the differential surface of the needle 2, overcomes the force exerted by the spring 7, or by the fuel in the closed cylindrical space 53, the needle 2 is lifted whereby it opens for the fuel a passage in the seat to jet holes 12, through which fuel flows into the combustion chamber (not shown) of the engine.

The function of an injector is well known and is therefore not fully described here.

By displacing the axis 531 of the space 53 through the distance e relative to the axis 21 of the needle 2, the volume of the body 5 of the injector may be better utilized, and in this way its radial dimensions may be considerably reduced.

The cylindrical guide 8 prevents radial forces from the spring 7 to be transmitted to the end of the differential needle 2.

Although the invention is illustrated and described with reference to one preferred embodiment thereof, it is to be expressly understood that it is in no way limited to the disclosure of such a preferred embodiment, but it is capable of numerous modifications within the scope of the appended claims.

1. An injector for combustion engines comprising an injection nozzle controlled by a differential needle, and a body defining a closed cylindrical space situated above the needle and accommodating a prestressed spring, the needle being, in operation, lifted both by the pressure of the fuel supplied to the injector and acting against said spring, and by the pressure of the fuel filling said space, wherein the axis of said space is spaced from and parallel to the axis of said needle, and a cylindrical guide is situated in said space between the spring and the upper end of the needle and guided slidably by the wall of said space.

2. An injector for combustion engines, constructed, arranged and adapted to operate substantially as herein described with reference to, and as shown in, the accompanying drawing.

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

Claims (2)

**WARNING** start of CLMS field may overlap end of DESC **. SPECIFICATION An injector for combustion engines The invention relates to an injector for combustion engines, the injector having a closed hole-injection nozzle, or a pin-injection nozzle, and being provided with a differential needle opened both by the pressure of injected fuel towards the injector against a prestressed spring situated in a closed cylindrical space, and by pressure of fuel filling the closed cylindrical space above the differential needle. In known designs of injectors for combustion engines, the closed cylindrical space above the differential needle of the injection nozzle is coaxial with the axis of the differential needle. A longitudinal channel is bored in the body of the injector along the closed cylindrical space. Through the said channel the delivered fuel is supplied to the injection nozzle. In this case the radial dimensions of the injector are relatively large, which is disadvantageous for modern engines. The aim of the invention is to devise an injector for combustion engines, the radial dimensions of which are as small as possible. The said aim is achieved by the invention in that the axis of the closed cylindrical space above the differential needle in the injection nozzle is spaced from and parallel to the axis of the differential needle, and between a spring seated in the closed cylindrical space and upper end of the differential needle is situated a cylindrical guide, guided slidably by a wall of the closed cylindrical space. In order that the invention may be clearly understood and radially carried into effect, a preferred embodiment thereof is, by way of example, hereinafter more fully described and illustrated in the accompanying diagrammatic drawing which shows a longitudinal section of the injector. An injection nozzle, comprising a body 1 and in it a lapped differential needle 2, is fixed to the lower face of the body 5 of the injector, through an insert 4, by means of a cup nut 3. In the body 5 of the injector is formed a closed cylindrical space 53 extending from its lower face. The axis 531 of the space 53 is parallel to the axis 21 of the needle 2, the two axes 21, 531 being spaced from each other by a distance e. A prestressed spring 7 is situated in the space 53. The upper end of the spring 7 bears onto an exchangeable insert 9, and its lower end onto a cylindrical guide 8, against the lower face of which bears the upper reduced end of the needle 2 passing freely through a central bore in the insert 4, the latter being also provided with a channel 41. The mutual position of the body 5 of the injector, of the insert 4 and of the body 1 of the injection nozzle is secured by at least one pin 6. A longitudinal channel 52 is bored in the body 5 of the injector from its lower face along the space 53. The said longitudinal channel 52 communicates in the upper part with an inclined channel 51 which in turn communicates with a bore 54, to which the outlet end of delivery piping (not shown) is connected. A pin 10 is used to ensure the desired position of the body 5 of the injector in the head (not shown) of the engine, which is pressed radially into the upper part of the body 5 of the injector. Fuel supplied into the channel 51 passes through the longitudinal channel 52 in the body 5 of the injector and through the channel 41 in the insert 4 into the channel 11 in the body 1 of the injection nozzle and to its seat, closed by the lower end of the needle 2. As soon as the pressure of the delivered fuel, acting from below onto the differential surface of the needle 2, overcomes the force exerted by the spring 7, or by the fuel in the closed cylindrical space 53, the needle 2 is lifted whereby it opens for the fuel a passage in the seat to jet holes 12, through which fuel flows into the combustion chamber (not shown) of the engine. The function of an injector is well known and is therefore not fully described here. By displacing the axis 531 of the space 53 through the distance e relative to the axis 21 of the needle 2, the volume of the body 5 of the injector may be better utilized, and in this way its radial dimensions may be considerably reduced. The cylindrical guide 8 prevents radial forces from the spring 7 to be transmitted to the end of the differential needle 2. Although the invention is illustrated and described with reference to one preferred embodiment thereof, it is to be expressly understood that it is in no way limited to the disclosure of such a preferred embodiment, but it is capable of numerous modifications within the scope of the appended claims. CLAIMS

1. An injector for combustion engines comprising an injection nozzle controlled by a differential needle, and a body defining a closed cylindrical space situated above the needle and accommodating a prestressed spring, the needle being, in operation, lifted both by the pressure of the fuel supplied to the injector and acting against said spring, and by the pressure of the fuel filling said space, wherein the axis of said space is spaced from and parallel to the axis of said needle, and a cylindrical guide is situated in said space between the spring and the upper end of the needle and guided slidably by the wall of said space.

2. An injector for combustion engines, constructed, arranged and adapted to operate substantially as herein described with reference to, and as shown in, the accompanying drawing.