WO1992019858A1

WO1992019858A1 - Screw-threaded assemblies

Info

Publication number: WO1992019858A1
Application number: PCT/GB1992/000626
Authority: WO
Inventors: Ronald Frederick Turner
Original assignee: Lucas Industries Public Limited Company
Priority date: 1991-05-02
Filing date: 1992-04-08
Publication date: 1992-11-12
Also published as: GB9109533D0

Abstract

A unit injector pump has an elecromagnetic actuator (20) mounted in the main body (10) of the injector pump. A collar (30) having internal and external screw threads (31, 32) is used to set the actuator in a required angular orientation with respect to the main body (10).

Description

SCREW-THREADED ASSEMBLIES BACKGROUND OF THE INVENTION This invention relates to screw-threaded assemblies.

It is often necessary to form electrical connections to the electrical terminals of a component which is a screw fit in a receiving socket. In such circumstances, the terminals could assume any final angular orientation relative to the socket, and this presents a problem if the electrical connections are to be made using a prefabricated wiring harness or wires of preset length. A problem has arisen, for example, when forming electrical connections to the terminal posts of the electromagnetic actuator for the unit injector pump of an engine, the actuator being a screw fit in a screw-threaded bore formed in the body of the injector pump.

It is an object of the present invention to provide a screw-threaded assembly which at least alleviates the afore-mentioned problems.

SUMMARY OF THE INVENTION According to one aspect of the invention, there is provided a screw-threaded assembly comprising a first component having an external screw thread, a second component having an internal screw thread and an intermediate screw-threaded member for enabling the first and second components to be assembled, wherein the intermediate screw-threaded member has an internal screw thread for engagement with the external screw thread of the first component and an external screw thread for engagement with the internal screw thread of the second component whereby the intermediate screw-threaded member enables the first and second components^' to be assembles with predetermined relative angular orientations.

In a screw-threaded assembly, as defined, the position of the intermediate screw-threaded member relative to the first and second components can be adjusted, enabling said predetermined relative angular orientations to be attained.

In a preferred embodiment of the invention, the intermediate screw-threaded member comprises a sleeve having said internal screw thread and said external screw thread, and the relative pitches of the internal and external screw threads of the sleeve are such as to enable the first and second components to be assembled in preset relative axial positions with said predetermined relative angular orientations.

The invention has particular, though not exclusive, application to screw-threaded assemblies in which one of the first and second components is an electrical component having one or more electrical terminals.

In this case, the intermediate screw-threaded member enables the relative angular orientations of the first and second components to be set so that the electrical terminals lie in a predetermined angular orientation whereby to enable electrical connectors to be attached.

In a particular example of this, one of the components is the electromagnetic actuator for a unit injector pump and the other component is the body of the injector pump, the electromagnetic actuator„being provided with at least two electrical terminals.

According to another aspect of the invention, there is provided a method for assembling a first component, having an external screw thread, and a second component having an internal screw thread, in predetermined relative angular orientations, including the steps of assembling the first and second components in preset relative axial positions by means of an intermediate screw-threaded member having an internal screw thread engageable with the external screw thread of the first component and an external screw thread engageable with the internal screw thread of the second component, causing relative angular displacement of the first and second components, whilst maintaining one of the first and second components and the intermediate screw-threaded member in fixed relative positions, whereby to displace the first and second components from said preset relative axial positions, adjusting the angular orientation of the intermediate screw-threaded member with respect to the first and second components, and then restoring the first and second components to said preset relative axial positions, the extent of the adjustment of angular orientation of the intermediate screw-threaded member being such that the first and second components have said predetermined relative angular orientations after they have been restored to said preset relative axial positions.

BRIEF DESCRIPTION OF THE DRAWINGS A screw-threaded assembly in accordance with the invention is now described, by way of example only, with reference to the accompanying drawings, in which:

Figure 1 shows a plan view of part of a unit injector pump for an engine; and

Figure 2 shows a part-sectional, longitudinal view of the unit injector pump of Figure 1, and illustrates the manner by which the electromagnetic actuator and the main body of the unit injector pump are assembled. BEST MODE OF CARRYING OUT THE INVENTION Referring now to Figures 1 and 2, the unit injector pump comprises a main body 10 having a screw-threaded bore 11, and an electromagnetic actuator 20 mounted in the bore 11.

The actuator 20 has two electrical terminal posts 21,21' which must lie in a predetermined angular orientation with respect to the main body to enable electrical connection sockets to be attached.

Furthermore, in order to operate correctly, the actuator 20 must be accurately located at a predetermined axial position in the bore.

To enable these requirements to be met, an intermediate screw-threaded sleeve 30 is provided.

The sleeve 30 has an external screw thread 31 which engages with an internal screw thread formed in the wall of the bore, and the sleeve also has an internal screw thread 32 which engages with an external screw thread of the actuator. O-ring seals 33,34 are provided to prevent fuel leakage.

As will now be explained, the position of the sleeve 30 in the bore can be so adjusted as to enable the actuator 20 to be assembled in the desired angular and axial positions with respect to the main body 10.

To that end, the sleeve 30 is initially screwed into the bore 11, to a mid-adjustment position, and the actuator is then screwed into the sleeve with a predetermined torque loading so as to be located at the required axial position with respect to the main body 10.

The actuator will probably not have the required angular orientation; however, with a knowledge of the relative pitches of the screw threads 31,32 it is possible to adjust the position of the sleeve 30 in the bore by the precise amount needed to bring the actuator (and so the two terminal posts) into the correct angular orientation. Such adjustment is affected by rotating the sleeve, clockwise or anti-clockwise as necessary, through an appropriate angle using a suitable tool engageable in slots 35 provided at the outer end of the sleeve.

In order to free the sleeve 30 for adjustment, the actuator is partially unscrewed, without altering the position of the sleeve relative to the main body 10, and the angular position of the sleeve is then adjusted by the required amount, taking into account the relative pitches of the screw threads 31,32. In this particular example, the external screw thread 31 has a 1.5mm pitch whereas the internal screw thread 32 has a 1.0mm pitch. Accordingly, by rotating the sleeve through an angle θ the angular orientation of the actuator can be displaced through an angle /_$ θ, and by this means the terminal posts 21,21' will have the correct angular orientation with respect of the main body 10 when the actuator is finally tightened down again so as to be located in the desired axial position.

It will be appreciated that instead of initially screwing sleeve 30 into the bore 11, it would alternatively be possible to screw the sleeve onto the actuator and then screw the sleeve and actuator into the bore.

INDUSTRIAL APPLICABILITY It will be understood that although the invention has been described with reference' to the assembly of a unit injector pump, the invention is applicable to screw- threaded assemblies generally, whose component parts are required to have preset relative angular orientations.

Claims

1. A screw-threaded assembly comprising a first component (20) having an external screw thread, a second component (10) having an internal screw thread and an intermediate screw-threaded member (30) for enabling . the first and second components (20,10) to be assembled, wherein the intermediate screw-threaded member (30) has an internal screw thread (32) for engagement with the external screw thread of the first component (20) and an external screw thread (31) for engagement with the internal screw thread of the second component (10) whereby the intermediate screw-threaded member (30) enables the first and second components (20,10) to be assembled with predetermined relative angular orientations.

2. A screw-threaded assembly as claimed in claim 1, wherein the intermediate screw-threaded member (30) comprises a sleeve having said internal screw thread (32) and said external screw thread (31), and the relative pitches of the internal and external screw threads (32,31) of the sleeve are such as to enable the first and second components (20,10) to be assembled in preset relative axial positions with said predetermined relative angular orientations.

3. A screw-threaded assembly as claimed in claim 1 or claim 2, wherein one of the first and second components (20,10) is an electrical component having one or more electrical terminals.

4. A screw-threaded assembly as claimed in claim 3, wherein said one of the components (20) is the electromagnetic actuator for a unit injector pump and the other component (10) is the body of the injector pump, and the electromagnetic actuator has at least two electrical terminals (21,21').

5. A method for assembling a first component (20), having an external screw thread, and a second component (10) having an internal screw thread, in predetermined relative angular orientations, including the steps of assembling the first and second components (20,10) in preset relative axial positions by means of an intermediate screw-threaded member (30) having an internal screw thread (32) engageable with the external screw thread of the first component (20) and an external screw thread (31) engageable with the internal screw thread of the second component (10), causing relative angular displacement of the first and second components (20,10), whilst maintaining one of the first and second components (20,10) and the intermediate screw-threaded member (30) in fixed relative positions, whereby to displace the first and second components (20,10) from said preset relative axial positions, adjusting the angular orientation of the intermediate screw-threaded member (30) with respect to the first and second components (20,10), and then restoring the first and second components (20,10) to -said preset relative axial positions, the extent of the adjustment of angular orientation of the intermediate screw-threaded member (30) being such that the first and second components (20,10) have said predetermined relative angular orientations after they have been restored to said preset relative axial positions.

6. A method as claimed in claim 5, wherein the intermediate screw-threaded member (30) is adapted to receive a tool for effecting said adjustment of angular orientation.