EP2348586A1

EP2348586A1 - Apparatus for electrical connection

Info

Publication number: EP2348586A1
Application number: EP10151182A
Authority: EP
Inventors: Jerome Calonne; Martin Hardy
Original assignee: Delphi Technologies Holding SARL
Current assignee: Delphi Technologies Operations Luxembourg SARL
Priority date: 2010-01-20
Filing date: 2010-01-20
Publication date: 2011-07-27
Also published as: WO2011088940A1

Abstract

Apparatus is disclosed that is suitable for connecting first and second electrical connection points arranged at different angular orientations, for example in a fuel injector having a pressure sensor integrated into a cap nut. The apparatus comprises a generally cylindrical first body (118) having a first electrical connection point (B), a generally tubular second body (122) attachable to an end region (120) of the first body (118) and having a second electrical connection point (136), a first annular conductor (152) associated with the first body (118) and connected to the first connection point (B), and a second annular conductor (164) associated with the second body (122) and connected to the second connection point (136). The first and second connection points (B, 136) are located laterally from a common axis (A) of the first and second bodies (118, 122) and, when the second body (122) is attached to the first body (118), the first and second annular conductors (152, 164) are in electrical contact so as to connect the first connection point to the second connection point (136) irrespective of whether the first and second connection points are in alignment in a direction parallel to the common axis (A).

Description

Field of the invention

The present invention relates to apparatus for providing an electrical connection between two components. In particular, but not exclusively, the invention relates to an apparatus for providing an electrical connection between two cylindrical components of a fuel injector for an internal combustion engine.

Background to the invention

One type of fuel injector for use in internal combustion engines comprises an elongate, generally tubular or cylindrical nozzle holder body, and a nozzle. The nozzle houses a valve needle of the injector. The valve needle is moveable to control the flow of fuel through outlets in the nozzle. Movement of the valve needle is controlled by an actuator arrangement housed in the nozzle holder body. In use of the injector, the nozzle is positioned in communication with a combustion chamber of an internal combustion engine, and the injection of fuel from the injector into the combustion chamber through the outlets is controlled by operation of the actuator arrangement.
As shown schematically in Figure 1 of the accompanying drawings, the nozzle 10 comprises an elongate portion 12 of relatively small outside diameter and having an axial bore 14 for receiving the valve needle (not shown), and a collar portion 16 of relatively large outside diameter. The outside diameter of the collar portion 16 approximately matches the outside diameter of an end region 20 of the nozzle holder body 18. The collar portion 16 of the nozzle 10 abuts the end region 20 of the nozzle holder body 18, and is held in position by a fastening member or cap nut 22.
The cap nut 22 comprises a generally tubular element having a first portion 24 with an inside diameter similar to the outside diameters of both the end region 20 of the nozzle holder body 18 and the collar portion 16 of the nozzle 10, and a second portion 26 with an inside diameter similar to the outside diameter of the elongate portion 12 of the nozzle 10. The first portion 24 of the cap nut carries internal screw threads that mate with complementary external screw threads provided on the end region 20 of the nozzle holder body 18. The difference in the inside diameter of the first and second portions 24, 26 of the cap nut 22 provides a shoulder 28 of the cap nut 22, which abuts the collar portion 16 of the nozzle 10. In this way, when the cap nut 22 is screwed on to the end region 20 of the nozzle holder body 18, the collar portion 16 of the nozzle 10 is clamped against the nozzle holder body 18 by the cap nut 22.
In some cases, it may be desirable to provide an electrical connection between the nozzle holder body and the cap nut. For example, the present applicant's granted European Patent No. EP-B-1854993 describes an arrangement in which a pressure sensor is integrated into the cap nut of a fuel injector. The pressure sensor is arranged to measure the gas pressure within the combustion chamber associated with the injector, and is located on one side of the cap nut.
In such an arrangement, electrical connections between the injector and a control system of the engine are made at a connection point at an end of the nozzle holder body opposite the nozzle. Consequently, at least one electrical connection, typically a signal cable, must bridge from the connection point on the nozzle holder body to the pressure sensor in the cap nut. Due to space restrictions within the nozzle and the nozzle holder body, it is preferable for the signal cable to be provided on the outside of the body of the fuel injector.
It is desirable to design fuel injector components so that most or all of the assembly of a fuel injector can be automated. For this reason, it is preferred that the signal cable extends in a direction parallel to the common longitudinal axis of the nozzle holder body, the nozzle, and the cap nut.
It will be appreciated that, when the cap nut is screwed on to the nozzle holder body during assembly of an injector of the type described in EP-B-1854993 , the angular position of the cap nut pressure sensor may not correspond to the angular position of the connection point on the nozzle holder body. In this event, the signal cable would not extend in the preferred axial direction. Furthermore, due to manufacturing tolerances and other factors, the angular spacing between the pressure sensor and the connection point may vary between injectors, leading to further difficulties in manufacturing the injector using an automated process.
It would therefore be desirable to provide an arrangement that overcomes or alleviates these problems, and it is against this background that the present invention has been devised.

Summary of the invention

According to a first aspect of the present invention, there is provided an apparatus comprising a generally cylindrical first body having a first electrical connection point, a generally tubular second body attachable to an end region of the first body and having a second electrical connection point, a first annular conductor associated with the first body and connected to the first connection point, and a second annular conductor associated with the second body and connected to the second connection point. The first and second connection points are located laterally from a common axis of the first and second bodies. When the second body is attached to the first body, the first and second annular conductors are in electrical contact so as to connect the first connection point to the second connection point irrespective of whether the first and second connection points are in alignment in a direction parallel to the common axis.
Since the apparatus allows an electrical connection to be made between the first and second connection points even when the first and second connection points are angularly misaligned about the common axis, the present invention provides a solution to the problem of making an electrical connection between two bodies that are rotated or turned with respect to one another during assembly and/or use of a device.
The first and second annular conductors may be biased towards one another when the second body is attached to the first body. For example, at least one of the annular conductors may be resilient to deformation in a direction parallel to the common axis to bias the annular conductors towards one another. In this way, a robust and reliable electrical connection can be facilitated that is unaffected by vibration and the like.
In one embodiment, at least one of the annular conductors has a 'C'-shaped cross-section. In this way, one or both of the annular conductors act like a spring that pushes against the other annular conductor when the second body is attached to the first body.
The annular conductors may be fixed to the respective body so that, when a body is turned or rotated, the corresponding annular conductor turns or rotates along with the body.
The first body may comprise a shoulder defining the end region, and the first annular conductor may be located adjacent the shoulder.
The apparatus may comprise a first signal conductor to connect the first connection point to the first annular conductor, and/or a second signal conductor to connect the second connection point to the second annular conductor. The first signal conductor and/or the second signal conductor may extend in a direction parallel to the common axis, and may optionally be routed along the outside of the respective first or second body.
The first signal conductor and/or the second signal conductor may be disposed within respective insulating sleeves. In this way, the signal conductors can be electrically isolated from the first and second bodies and from an external body in which the apparatus is housed.
In one embodiment of the invention, the apparatus comprises a first insulating element for receiving the first annular conductor, and/or a second insulating element for receiving the second annular conductor. The first insulating element and/or the second insulating element may, for example, have a 'U'-shaped cross-section to define an annular recess for receiving the respective first or second annular conductor.
The first insulating element may be attached to the first body, and/or the second insulating element may be attached to the second body. For example, an insulating element may be adhesively attached or moulded to the respective body.
When provided, the insulating sleeve within which a first signal conductor is disposed may be integral with the first insulating element. Similarly, when provided, the insulating sleeve within which a second signal conductor may be disposed is integral with the second insulating element.
The second body may be in the form of a nut or fastening for holding or retaining a third body in contact with the first body. The first body may be of tubular or similar form.
In one example, the first body comprises a nozzle holder body of a fuel injector, and the second body comprises a cap nut of the fuel injector. The second connection point may comprise an output connection of a pressure transducer associated with the cap nut. The pressure transducer may, for example, be integrated with or housed in the cap nut. Accordingly, in a second aspect, the invention extends to a fuel injector comprising apparatus according to the first aspect of the invention.

Brief description of the drawings

Figure 1 of the accompanying drawings, which shows a cross-sectional view through part of a known fuel injector, has already been referred to above. The present invention will now be described, by way of example only, with reference to the remaining accompanying drawings, in which like reference numerals are used for like parts and in which:
Figure 2 is a cut-away perspective view of part of a fuel injector according to one embodiment of the present invention;
Figure 3(a) is a front view of part of the fuel injector of Figure 2;
Figure 3(b) is a cross-sectional view of the fuel injector of Figure 2, taken along line P-Q in Figure 3(a);
Figure 3(c) is an enlarged cross-sectional view of area R of Figure 3(b), showing part of the fuel injector in greater detail;
Figure 4(a) is a side view of part of the fuel injector of Figure 2;
Figure 4(b) is a cross-sectional view of the fuel injector of Figure 2, taken along line S-T in Figure 4(a); and
Figure 4(c) is an enlarged cross-sectional view of area U of Figure 4(b), showing part of the fuel injector in greater detail.

Detailed description of preferred embodiments of the invention

Referring to Figures 2 to 4(c), in one embodiment of the invention, there is provided a fuel injector 100 having a nozzle holder body 118, a nozzle 110, and a cap nut 122, arranged along a common axis A.
The cap nut 122 is generally tubular. An upper end portion 123 of the cap nut 122 is engaged with a threaded end region 120 of the nozzle holder body 118. An opposite end of the cap nut 122 comprises an end portion 126 having a relatively small inside diameter to define an internal shoulder 128 of the cap nut 122. The internal shoulder 128 abuts a collar portion 116 of the nozzle 110, so that the cap nut 122 retains the nozzle 110 against the nozzle holder body 118 in an end-to-end configuration.
As in the known fuel injector of Figure 1, in the fuel injector of Figures 2 to 4(c) the nozzle 110 houses a valve needle (not shown) for controlling the injection of fuel through one or more outlets (not shown), and the nozzle holder body 118 houses an actuator arrangement (not shown) for controlling movement of the valve needle. In use, the injector 100 is mounted in a cylinder head (not shown) of an internal combustion engine, so that the nozzle 110 and at least part of the cap nut 122 extend into a combustion chamber 130 of the engine.
As shown most clearly in Figures 2 and 4(b), the cap nut 122 comprises a recess 132 within which a pressure transducer 134 is received. The pressure transducer 134 may be of the type described in the present applicant's granted European Patent No. EP-B-1854993 , the contents of which are incorporated herein by reference. The pressure transducer 134 generates an output signal that relates to the gas pressure in the combustion chamber 130.
The output signal of the pressure transducer 134 must be relayed to an engine control unit (ECU, not shown) or similar device of the engine. The pressure sensor 134 is connected to the vehicle earth via the conducting metal of the cap nut 122, nozzle holder body 118 and cylinder head, therefore only a single electrical connection between the transducer 134 and the ECU is required in this embodiment.
The pressure transducer 134 comprises an output connection 136 for the electrical signal. The output connection 136 is associated with an outwardly-directed face 138 of the pressure transducer 134. The injector 100 comprises a connection point on or adjacent to an outside surface of the nozzle holder body 118 from which a connection between the injector 100 and the ECU is made. The connection point is not shown in the accompanying drawings, but the location of the connection point is indicated by the reference sign "B" in Figures 2, 3(a) and 3(b). It is necessary to provide an electrical connection between the output connection 136 of the pressure transducer 134 and the connection point B on the nozzle holder body 118. According to the invention, the electrical connection is achieved by the provision of annular electrical conductors arranged between the cap nut 122 and the nozzle holder body 118, as will now be described.
As shown most clearly in Figure 3(b), a body signal conductor 138 in the form of a metallic strip extends from the connection point B on the nozzle holder body 118 towards the end region 120 of the nozzle holder body 118. The body signal conductor 138 runs along the outside surface of the nozzle holder body 118, so that the body signal conductor 138 is laterally or radially spaced from, but parallel to, the axis A.
The body signal conductor 138 is housed within a sleeve 142. The sleeve 142 is of an electrically insulating plastics material, and serves to prevent electrical contact between the conductor 138 and the nozzle holder body 118, and between the conductor 138 and the cylinder head and other engine components in use of the injector 100. The nozzle holder body 118 comprises a flat 140 on the front face thereof, as shown in Figure 3(a), to accommodate the body signal conductor 138 and the sleeve 142.
The end region 120 of the nozzle holder body 118 has a smaller outside diameter than the remainder of the nozzle holder body 118, so that the end region 120 is defined by a shoulder 144 of the nozzle holder body 118. As shown most clearly in Figure 3(c), a first annular insulating element 148, made from an electrically insulating plastics material, abuts the shoulder 144. The first insulating element 148 has a generally 'U'-shaped cross-section, arranged such that the base of the 'U'-shape abuts the shoulder 144 and such that an annular recess 150 is formed in the face of the element 148 opposite the shoulder 144, between the arms of the 'U'-shape.
A first annular conductor, comprising a first conducting ring 152, is received in the recess 150 of the first insulating element 148. The first conducting ring 152 comprises a metallic strip formed into a 'C'-shaped cross-section. The open part of the 'C'-shape faces the outer arm of the 'U'-shape of the first insulating element 148. In this way, the first conducting ring 152 functions as a spring that is resilient to deformation in a direction parallel to the axis A.
The sleeve 142 extends downwardly to overlap or connect at its lowermost end with the first insulating element 148. The body signal conductor 138 extends through the first insulating element 148 to connect with the first conducting ring 152. In this way, the first conducting ring 152 is in electrical communication with the connection point B on the nozzle holder body 118.
Referring now to Figures 4(b) and 4(c) in particular, a cap nut signal conductor 154 extends from the output connection 136 of the pressure transducer 134 of the cap nut 122 towards the nozzle holder body 118. The cap nut signal conductor 154 comprises a metallic strip that runs along the outside surface of the cap nut 122, so that, like the body signal conductor 138, the cap nut signal conductor 154 is laterally or radially spaced from, but parallel to, the axis A. As for the body signal conductor 138, the cap nut signal conductor 154 is housed within a sleeve 156 of an electrically insulating plastics material.
A second annular insulating element 160, made from an electrically insulating plastics material, extends around and abuts an end face 162 of the cap nut 122. The second insulating element 160 also has a generally 'U'-shaped cross-section, arranged such that the base of the 'U'-shape abuts the shoulder end face 162 of the cap nut 122 and such that an annular recess 162 is formed in the face of the element 160 opposite the shoulder end face 162, between the arms of the 'U'-shape.
A second annular conductor, comprising a second conducting ring 164, is received in the recess 162 of the second insulating element 160. The second conducting ring 164 comprises a metallic strip formed into a 'C'-shaped cross-section of the same form as the first conducting ring 152 so that the second conducting ring 164 acts as spring that is resilient to deformation in a direction parallel to the axis A.
At its uppermost end, the upper portion 123 of the cap nut 122 comprises a flange region 166 that protrudes slightly in a radial direction from the remainder of the upper portion 123. The sleeve 156 that houses the cap nut signal conductor 154 follows the contour of the flange region 166 so as to overlap or connect at its uppermost end with the second insulating element 160. The cap nut signal conductor 154 extends through an axial slot or drilling 168 in the flange region 166 to connect with the second conducting ring 164. In this way, the second conducting ring 164 is in electrical communication with the output connection 136 of the pressure transducer 134.
The first insulating element 148 and the associated first conducting ring 152 are fixed with respect to the nozzle holder body 118. For example, the first insulating element 148 may be adhesively attached to the shoulder 144 of the nozzle holder body 118 so as to prevent rotation of the first insulating element 148 relative to the nozzle holder body 118. Similarly, the second insulating element 160 and the associated second conducting ring 164 are fixed with respect to the cap nut 122. For example, the second insulating element 160 may be adhesively attached to the end face 162 of the cap nut 122.
During assembly of the fuel injector 100, the cap nut 122 is screwed on to the threaded end region 120 of the nozzle holder body 118. As the cap nut 122 is screwed into place, the first and second insulating elements 148, 160 become pressed against one another, so that the respective recesses 150, 162 are in communication. The first and second conducting rings 152, 164 are therefore pressed or held together, so as to form an electrical connection.
In this way, an electrical connection is provided between the connection point B on the nozzle holder body 118 and the output connection 136 of the pressure transducer 134 of the cap nut 122, irrespective of whether the connection point B and the output connection 136 are aligned in a direction parallel to the axis A. In other words, an electrical connection is achieved even when the connection point B and the output connection 136 are in angular misalignment.
The conducting rings 152, 164 and signal conductors 138, 154 are preferably of a metallic material with good electrical conductivity and suitable mechanical properties, such as copper. However, any other suitable material could be used.
The spring-like form of the first and second conducting rings 152, 164 ensures that a reliable, low resistance electrical contact is made between the rings 152, 164. Preferably, before assembly of the injector 100, the components are arranged so that each ring 152, 164 protrudes slightly out of its respective recess 150, 162. In this way, when the first and second insulating elements 148, 160 are pressed against one another during assembly of the injector 100, the first and second conducting rings 152, 164 are deformed against their resilience so as to ensure a sound electrical contact when the injector 100 is subject to vibration and other adverse operating conditions.
Furthermore, the cap nut 122 clamps the second insulating element 160 against the first insulating element 148. In this way, a fluid-tight seal is formed between the first and second insulating elements 148, 160 so as to prevent fluid such as fuel from coming into contact with the conducting rings 152, 164.
It will be appreciated that several variations and modifications could be made to the invention, and several optional features could be included.
For example, the first and second conducting rings 152, 164 may optionally be moulded into the plastics material of the first and second insulating elements 148, 160, respectively. The conducting rings 152, 164 may instead be an interference fit in the respective recesses 150, 162 of the insulating elements 148, 160, or could be adhesively fixed.
Optionally, the end faces of one or both of the insulating elements 148, 160, adjacent the respective recesses 150, 162, may comprise sealing means to enhance the seal between the insulating elements 148, 160. The sealing means may comprise, for example, one or more annular sealing ridges. Conceivably, the sealing means could comprise an 'o' ring provided in a face of an insulating element 148, 160.
The insulating elements 148, 160 may be formed integrally with the respective sleeves 142, 156. For example, the insulating elements 148, 160 may be formed in a single injection moulding process with the respective sleeves 142, 156. In another embodiment, the sleeves 142, 156 are over-moulded onto the insulating elements 148, 160. The sleeves 142, 156 may be glued or otherwise attached to the outside of the nozzle holder body 118 and the cap nut 122, respectively.
In the described embodiment, the first and second annular conductors comprise rings 152, 164. It will be appreciated, however, that complete circular rings need not be provided. Instead, conductors having part-circular or semi-circular form could be used, provided sufficient overlap of the conductors is achieved when the cap nut 122 is screwed on to the nozzle holder body 118.
In the described embodiment, the conducting rings 152, 164 derive their resilience from the spring-like shape of the rings 152, 164. It is conceivable, however, that the rings 152, 164 may not be spring-like, in which case a separate biasing arrangement could be used to bias the rings 152, 164 into contact. For example, one or both rings could be mounted on an 'o' ring or on a separate spring ring.
The connection point B on the nozzle holder body may comprise an electrical connector, such as a plug or socket, arranged to mate with a complementary connector for connection to an ECU or other device of the engine. In another embodiment, the connection point B comprises an on-board microprocessor or other electronic device, such as an electronic charge amplifier.
Although embodiments of the invention have been described with reference to a fuel injector, it will be appreciated that the present invention could be used in other situations where it is necessary to make an electrical connection between two points that may be in angular misalignment about a common axis after assembly.
As will be appreciated by a person skilled in the art, further modifications and variations not explicitly described above are also possible without departing from the scope of the invention as defined in the appended claims.

Claims

Apparatus comprising:
a generally cylindrical first body (118) having a first electrical connection point (B);

a generally tubular second body (122) attachable to an end region (120) of the first body (118) and having a second electrical connection point (136);

a first annular conductor (152) associated with the first body (118) and connected to the first connection point (B); and

a second annular conductor (164) associated with the second body (122) and connected to the second connection point (136);

wherein the first and second connection points (B, 136) are located laterally from a common axis (A) of the first and second bodies (118, 122);

and wherein, when the second body (122) is attached to the first body (118), the first and second annular conductors (152, 164) are in electrical contact so as to connect the first connection point (B) to the second connection point (136) irrespective of whether the first and second connection points (B, 136) are in alignment in a direction parallel to the common axis (A).
Apparatus according to Claim 1, wherein the first and second annular conductors (152, 164) are biased towards one another when the second body (122) is attached to the first body (118).
Apparatus according to Claim 2, wherein at least one of the annular conductors (152, 164) is resilient to deformation in a direction parallel to the common axis (A) to bias the annular conductors (152, 164) towards one another.
Apparatus according to Claim 3, wherein the at least one of the annular conductors (152, 164) has a 'C'-shaped cross-section.
Apparatus according to any preceding Claim, wherein the first body (118) comprises a shoulder (144) defining the end region (120), and wherein the first annular conductor (152) is located adjacent the shoulder (144).
Apparatus according to any preceding Claim, comprising a first signal conductor (138) to connect the first connection point (B) to the first annular conductor (152), and/or a second signal conductor (154) to connect the second connection point (136) to the second annular conductor (164).
Apparatus according to Claim 6, wherein the first signal conductor (138) and/or the second signal conductor (154) extend in a direction parallel to the common axis (A).
Apparatus according to Claim 6 or Claim 7, wherein the first signal conductor (138) and/or the second signal conductor (154) are disposed within respective insulating sleeves (142, 156).
Apparatus according to any preceding Claim, comprising a first insulating element (148) for receiving the first annular conductor (152), and/or a second insulating element (160) for receiving the second annular conductor (154).
Apparatus according to Claim 9, wherein the first insulating element (148) and/or the second insulating element (160) has a 'U'-shaped cross-section to define an annular recess (150, 162) for receiving the respective first or second annular conductor (152, 154).
Apparatus according to Claim 9 or Claim 10, wherein the first insulating element (148) is attached to the first body (118), and/or wherein the second insulating element (160) is attached to the second body (122).
Apparatus according to any of Claims 9 to 11 when dependent on Claim 8, wherein the insulating sleeve (142) within which the first signal conductor (138) is disposed is integral with the first insulating element (148) and/or the insulating sleeve (156) within which the second signal conductor (154) is disposed is integral with the second insulating element (160).
Apparatus according to any preceding Claim, wherein the first body comprises a nozzle holder body (118) of a fuel injector (100), and wherein the second body comprises a cap nut (122) of the fuel injector (100).
Apparatus according to Claim 13, wherein the second connection point comprises an output connection (136) of a pressure transducer (134) associated with the cap nut (122).
A fuel injector (100) comprising apparatus according to Claim 13 or Claim 14.