Internal-combustion engines – Charge forming device – Fuel injection system
Reexamination Certificate
1999-08-26
2001-05-29
Yuen, Henry C. (Department: 3747)
Internal-combustion engines
Charge forming device
Fuel injection system
C123S1980DA
Reexamination Certificate
active
06237571
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a fuel feed apparatus and, in particular, a high pressure fuel feed connection to a fuel injector in an internal combustion engine to provide a conduit for leak-back fluid, a method for fitting such apparatus and an engine including said apparatus.
High pressure fuel injection systems used in, for example, diesel engines may be of the type in which the fuel is provided to the injectors from a “common rail” (a high pressure fuel manifold from which fuel for injection is taken off upon demand from the injector). In such systems it can be convenient, to limit engine height or for other reasons, to pass fuel from the rail via a pressure tube into a port in a side face rather than an upper face of the injector.
The upper part of an injector of the aforementioned type will often be enclosed within the body of the cylinder head but it may be necessary for it to be contained within an enclosure such as a camshaft housing above the cylinder head, particularly where the cylinder head is of shallow height in order to limit engine height and/or weight.
Several problems may arise in connecting a side feed to an injector in the above mentioned systems. In particular, fuel leaking from the vicinity of the injector connection may mix with and dilute engine lubricating oil carried within or above the cylinder head. This problem is exacerbated in that the leakage will normally be out of the sight of the engine operator.
Further problems arise with injectors of this type in that side forces may be imparted to the injector body which may cause deformation of the body and hence sticking of the injector moving parts. This situation can be particularly severe where the engine design does not readily permit the upper part of the injector to be directly supported by the cylinder head.
A further problem is the angular or lateral misalignment that can occur at the interface between the fuel feed conduit and the injector body. A rigid connection having limited means for correction of mis-alignment or tolerance build-up may lead to exacerbated fuel leakage at the interface and/or stress either at the connection or within the injector body.
2. Description of the Related Art
The problem in making a secure and leak-proof fuel feed connection to a side feed injector has been addressed in prior art. For example, U.S. Pat. No. 5,365,907 discloses a side feed connection to an injector in which arrangement a pressure tube is located in a recess in the cylinder head so that an inner end seats against a fuel inlet port in the injector and the tube is forced into firm engagement with the injector by a threaded tube-nut screwed into the cylinder head. The outer end of the tube extends through the tube-nut and is terminated in a means for securing a fuel supply pipe.
Patent application GB 2310891-A discloses a similar arrangement wherein a pressure tube having a frusto-conical collar is forced into engagement with the injector by a loose flange which bears on the collar and is retained to the cylinder head by threaded fasteners. Patent application JP 08-144886-A discloses a further arrangement in which a pressure tube passes through a passage in the cylinder head and into engagement with the injector and is terminated at an outer end by a flange. However none of the prior art discloses an injector side feed apparatus which would be suitable for fitment above, rather than within, the body of a cylinder head.
In cases where, for example, the space take within the cylinder head by the gas exchange mechanism leaves insufficient room for fitment of an injector side feed connection, or the cylinder head has only a shallow height, it may be convenient instead to make the connection above the cylinder head. In such cases, there would not be available the direct support of an upper part of the injector by the body of the cylinder head to resist the side forces which may be imparted by attachment of conventional side feed connections and this could result in bending of the injector.
In addition to a fuel feed, fuel leak-back provision is required with several common-rail injection systems because a portion of the fluid supplied is used in controlling the internal operation of and/or cooling of the injector and is then returned to the fuel feed system. It is otherwise known for fuel leak-back from an injector to be provided by direct communication between a relatively low leak-off port in an injector communicating with passages within a cylinder head but the long, small diameter, drillings in a cylinder head for this provision may be difficult to machine.
Patent DE 4427717-C1 teaches an apparatus capable of making a fuel feed connection to a side of an injector at a point above a main body of a cylinder head and due to the sliding nature of the connection side loading of the injector body can be minimised or avoided. However, there is no provision of appropriate means for fuel leak-back from the injector to a take-off point, and the leak-back path disclosed is of relatively high resistance, due to the presence of a threaded portion.
OBJECTS AND SUMMARY OF THE INVENTION
It is an object of the present invention to provide an apparatus and method for secure fuel leak-back transfer from a side feed injector to a take-off point for return to the fuel feed system, and especially to provide an apparatus and method for transferring fuel leakage from a high pressure side feed injector connection to a low pressure leak-back means for re-use, whilst introducing minimal additional side loading to the injector body.
It is a further object of the present invention to provide an apparatus and a method enabling the connection of a pressure tube to a side feed injector at a position above the body of a cylinder head and in a manner which will avoid or mitigate side loading of the injector.
It is a further object of the present invention to provide an apparatus and a method which includes a means to facilitate precise alignment between the pressure tube and the inlet port of the injector.
According to a first aspect of the invention, an apparatus for connecting a fuel pressure tube to a side feed injector device of an internal combustion engine, said injector device including an injector body having a fuel feed aperture on a side wall, comprises holder means for fitting onto an injector body serving to receive a fuel pressure tube, a housing member for said holder means configured to co-operate in use with said holder means to define a leak-back receptacle, ductings being provided in said holder means and said housing member to enable communication of a leak-back flow of fuel from the injector to the leak-back receptacle, and discharge means being provided in the receptacle to enable controlled delivery of the leak-back fuel for re-use.
The apparatus thus provides a simple and relatively direct fuel leak-back transfer for fuel emitted from the side feed injector to a take-off point for return to the fuel feed system. The apparatus is particularly suited to transferring leak-back fuel from a high pressure side feed injector connection to a low pressure leak-back means for re-use.
Preferably the housing member comprises a main support member adapted to be secured to a body part of the internal combustion engine and a carrier member for the holder device adapted to be secured to the main support member such that the holder device is movable in the carrier member, whereby the holder device can be fitted on to the injector body so as to take up an operative position whereat the nose portion of the fuel pressure tube is seated at the fuel feed aperture on the side wall of the injector body so that the holder device is retained on the injector body but with relative movement possible between the holder device and the carrier member.
Such an arrangement facilitates controlled loading of the pressure tube in the operative position and the securing of an effective seal whilst minimising excessive side-loading of the injector body
Preferably the holder device comprises a
Gimie Mahmoud M
Hickman Alan J.
Perkins Engines Company Limited
Yuen Henry C.
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