Internal-combustion engines – Charge forming device – Fuel injection system
Reexamination Certificate
1999-05-07
2001-03-06
Miller, Carl S. (Department: 3747)
Internal-combustion engines
Charge forming device
Fuel injection system
C123S509000
Reexamination Certificate
active
06196194
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to apparatus and method for clamping a fuel injector in place on an internal combustion engine and an engine including such apparatus.
A clamp for an internal combustion engine injector must securely retain the injector against the forces generated within the engine cylinder and the clamping means must be readily accessible for installation and removal of the injector.
The technical and commercial advantages associated with minimising engine envelope size and the increasing fitment of multi-camshaft and multi-valve systems have reduced the available space for fitting a clamp retaining means closely adjacent to the injector, this being particularly the case in engines fitted with relatively large injectors as exampled by hydraulically or mechanically actuated and electronically controlled unit injectors. This provides an incentive for fitting clamp retaining means away from the injector if possible.
A further problem can arise if the injector clamping counterload is directed into an area of the engine located near the injector insertion point in the cylinder head. For example, any threaded holes provided for clamp retaining fasteners which are located adjacent to the injector may weaken a critical part of the cylinder head or may break through into an injector coolant jacket and thus require sealing against leakage. In these circumstances, it is again advantageous if the injector clamping counterload is located away from this critical area.
Further, injector removal and refitment may be required during engine servicing and it is therefore beneficial to minimise impedance to access and the time required for injector removal and refitment. In the prior art, the operations of fitting or removing a unit injector have generally required the complete removal and replacement of one or more threaded fasteners and hence, particularly in an engine with a high number of injectors, these operations are undesirably time consuming.
2. Description of the Related Art
An example of prior art means for clamping hydraulically actuated, electronically controlled, unit injectors may be seen in U.S. Pat. No. 5,499,612. Clamping means for other types of injectors may be seen in GB 2213197, U.S. Pat. Nos. 4,206,725 and 4,246,877.
OBJECTS AND SUMMARY OF THE INVENTION
It is an object or the present invention to provide an apparatus and a method for securely clamping an injector in an internal combustion engine whereby the means for retention of the clamp to the engine may be located distant from crowded and potentially critical loadbearing areas in the immediate vicinity of the injector.
It is a further object of the invention to provide an injector clamping apparatus and method which give relative ease of access to the injector so as to furnish a means for relatively rapid removal and refitment of an injector in a built engine.
According to one aspect of the invention, clamping means for clamping a fuel injector in place on an engine comprises a clamp adapted to engage clamp support means on an engine having a first end adapted to engage an injector body, a clamping force receiving portion, and a fulcrum portion wherein the upper surface of the clamp is adapted in use to engage a fulcrum point on the engine in rolling contact, and clamp force applying means that engages the clamp at the force receiving portion and co-operates with the fulcrum portion to apply a clamping load through the clamp to the injector body.
It has been mentioned that it is desirable that the means for retention of the clamp to the engine is located distant from crowded and potentially critical load bearing areas in the immediate vicinity of the injector. The fulcrum portion is preferably located between the first end and the clamping force receiving portion, which clamping force receiving portion is then preferably located towards the second end of the clamp. This assists in ensuring that the means by which the clamp is retained to the engine can be located at a greater distance from the injector.
The fulcrum portion preferably comprises a segmentally cylindrical portion on the upper surface of the clamp.
The first end of the clamp preferably engages the injector body in rolling contact. This assists in accurate axial transmission of the load. The clamp is conveniently bifurcated comprising a pair of arms which in use are in close co-operation with a pair of opposed flat surfaces on an injector body.
Conveniently each of the arms has an arcuate lug on its lower edge which engages a corresponding shoulder adjacent one of the pair of opposed flat surfaces on the injector so as to form points of rolling contact that lie in a plane through the axis of the injector so as to apply an axial clamping load to the injector.
According to a second aspect of the present invention there is provided an internal combustion engine structure provided with a fuel injector, said injector clamped in place on the engine by clamping means comprising a clamp engaging clamp support means on the engine and having a first end adapted to engage an injector body, a clamping force receiving portion, and a fulcrum portion, preferably comprising a curved upper surface in engagement with a fulcrum point on the engine at a point of rolling contact, and clamp force applying means that engages the clamp at the force receiving portion and co-operates with the fulcrum portion to apply a clamping load through the clamp to the injector body.
Again the fulcrum portion is preferably located between the first end and the clamping force receiving portion. The clamping force receiving portion is preferably located towards the second end of the clamp. The first end of the clamp preferably engages the injector body in rolling contact and is conveniently bifurcated comprising a pair of arms which in use are in close co-operation with a pair of opposed flat surfaces on an injector body and each of which has an arcuate lug on its lower edge which engages a corresponding shoulder adjacent one of the pair of opposed flat surfaces on the injector so as to form points of rolling contact that lie in a plane through the axis of the injector so as to apply an axial clamping load to the injector.
This aspect of the invention offers particular advantages in relation to hydraulically actuated electronically controlled unit injector (HEUI) systems where the engines are fitted with relatively large injectors which have the effect of limiting the available space for fitting any clamp closely adjacent to the injector, since clamp means in accordance with the present invention can be relatively remotely fixed.
Such (HEUI) systems utilise fluid supply means such as a high pressure pump to transmit actuating fluid to the injector typically via a supply manifold where it is stored in readiness for actuating the injector under electronic control.
A preferred actuating fluid is engine lubricating oil. Conveniently oil drain means are provided to return the oil to the engine sump.
In a particularly preferred embodiment of an (HEUI) injected engine in accordance with the invention the engine structure is provided with an actuating fluid supply system comprising a fluid supply manifold defining an internal fluid reservoir and means for communicating actuating fluid from the reservoir to an injector, said fluid supply system being engaged in place on the engine in such configuration that a lower surface of the manifold provides the fulcrum point to engage the fulcrum portion of the clamp to provide a point of rolling contact.
Such an arrangement keeps the manifold out of the way of the clamp retaining means facilitating easy removal and insertion of the clamp. In addition because of the location of the manifold a relatively short fluid outlet channel is provided which minimises leaks and pressure drop as fluid is communicated from the fluid reservoir to the injector on actuation.
Preferably the manifold is adapted to provide a planar surface at the fulcrum point of engagement with the curved upper surface of the clamp
Hickman Alan J.
Miller Carl S.
Perkins Engines Company Limited
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