DE9114433U1 - Socket-type connection contact for spark plug connector - Google Patents

Description

PATENT ATTORNEYS ' Reference number

DiPL-iNG. CONRAD KÖCHLING __._.__

DiPL-iNG. CONRAD-JOACHIM KÖCHLING

FleyerStraße 135, D-5800 Hagen 1 Note: BREMI AUTO-ELEKTRIK

Call(02331)81164 + 85033 BREMICKER GMBH. + CO

Fax(02331) 84840 _ „ _

Telegrams: Patent cook Hagen Friedrich-Ebert~btr . Zl/

Accounts: Commerzbank AG, Hagen3515095 (bank code 450 40042)

Sparkasse Hagen 100012043 (bank code 45050001) _T , ,- _Q &ogr;&ogr;

Postgiro: Dortmund5989-460(BLZ44010046) W-DOOO

VNR: ...1.1 5.8...51

Serial No. .....1O43-9../.91 CJ.K/..G..

15 November 1991

Socket-type connection contact for
Spark plug connector

The invention relates to a socket-like connection contact for spark plug connectors, wherein the connection contact has a spring element inserted into its socket and can be releasably plugged onto a contact pin of a spark plug provided with an annular locking groove under pre-tension of the spring element.

Such socket-like connection contacts are known, for example, from DE 37 01 396 Al. These socket-like connection contacts are part of spark plug connectors, which have an interference suppression resistor embedded in an insulating body, at the end of which on the spark plug side the socket-like connection contact with a spring element is provided.

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The socket-like connection contact is formed by a socket element made of electrically conductive material, into which a radially spring-expandable sleeve made of metallically conductive material is inserted. The entire socket element including the interference suppression plug is embedded in a plastic body. The socket element consists of a base part and a jacket part, which are inserted into one another with a press fit. The jacket of the socket has a considerably larger inner diameter than the spring element, because in order to allow the spring element to spring back, there must be sufficient space between the jacket and the jacket. An inwardly projecting locking cam is formed on the spring sleeve, which automatically snaps into an annular groove in the contact pin when the spark plug contact pin is inserted into the socket.

The total external dimensions of the socket part surrounded by insulating material are limited by the installation conditions. As a result, the wall thickness of the insulating material body in the area of the socket is relatively small.

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According to the ISO standard, the contact pin of the spark plug is designed in such a way that it transitions from its conically tapered end into a narrow cylindrical area, which is followed by a conically tapering area with a flat angle of inclination as the groove flank. The groove base is in turn formed by a cylindrical area that is smaller in diameter than the cylindrical area mentioned above, which is followed by a narrow conical flank, from where the contact pin transitions cylindrically to the spark plug.

The disadvantage of the known design is that there is a relatively high specific surface pressure between the locking cam of the spring sleeve and the contact pin of the spark plug. This causes a change in the insertion and removal force of the socket-like connection contact during continuous operation because the relatively hard spring with the locking cam digs into the contact pin.

In addition, there is an asymmetrical load on the sleeve spring, locking cam and contact pin of the spark plug, which is detrimental to a secure fit.

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In particular, the production of the locking cam is disadvantageous as it leads to a high specific stress on the production tool and the spring sleeve.

This results in high tool wear and tear on the one hand and the risk of cracks in the spring on the other. Another disadvantage is that the push-on force of the socket-like connection contact is equal to the pull-off force.

This means that either a high spring preload must be applied, which results in a corresponding difficulty when plugging the socket-type connection contact onto the contact pin and also leads to the aforementioned high specific surface pressure between the locking cam and the contact pin, or a lower spring preload is set, which results in the seat of the socket-type connection contact not necessarily being guaranteed under continuous vibration loads and, in addition, the desired contact is impaired.

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Based on the prior art described at the outset, the invention is based on the object of creating a socket-like connecting contact of the generic type, in which the push-on force when pushing onto the contact pin of a spark plug is lower than the pull-off force when pulling it off the contact pin, in which a high long-term constancy of the mechanical and electrical properties is achieved after continuous vibration stress with high acceleration values and after multiple repetitions of the push-on and pull-off process, in which a slim structure, i.e. the smallest possible external diameter, is possible in order to achieve relatively large wall thicknesses of the surrounding plastic material, whereby a dimensional connection in a stable end position is also achieved and cost-effective production with low tool wear and low tendency of the spring to crack is achieved, and which is also beneficial to a consistently good manufacturing quality.

To solve this problem, it is proposed that the spring element is designed as a pipe section or as a longitudinally slotted sleeve, from the wall of which

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several spring tabs are cut out, evenly distributed around the circumference, the bending edge of which runs transversely to the plug-in axis (central longitudinal axis) of the connection contact and the free ends of which can be inserted into the locking groove of the contact pin under spring preload.

Preferably, three spring tabs are evenly distributed around the circumference.

This design ensures a secure fit and good contact even with a relatively low specific surface pressure between the free ends of the spring tabs and the contact pin of the spark plug.

Even under continuous use, a change in the insertion and removal force is not to be expected because the spring arms do not dig into the material of the contact pin or only do so insignificantly.

The symmetrical arrangement of the spring tabs ensures symmetrical clamping between the connection contact and the contact pin, which is beneficial for a secure fit and the long-term retention of the desired properties.

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Manufacturing is also simplified, as the formation of spring tabs on a pipe section or a longitudinally slotted sleeve is extremely simple and can be carried out with relatively little tool wear. In particular, when the spring element is formed as a sleeve, which is a preferred solution, the spring element can be provided with the spring tabs in a flat form by means of a punching and bending process and then formed into a sleeve. The desired mechanical and electrical properties are also largely retained even after continuous vibration loading with high acceleration values and after multiple repetitions of the insertion and removal process.

The design according to the invention also enables a slim construction, since, contrary to the teaching of the prior art, no radial spreading of the spring element is required, but only the spring arms have to be bent slightly around the bending edge. The corresponding free space can be created without significantly increasing the inner diameter of the socket part, so that the socket-like connection contact

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surrounding insulating material (plastic) can have a relatively larger wall thickness without the overall external diameter of the finished, overmolded socket-like connection contact having to be increased.

A particularly preferred development is that the spring tabs, when plugged onto the contact pin, have first surface areas that can be placed on first areas of the contact pin, by means of which the spring tabs can be pre-tensioned radially outwards and can be pivoted resiliently around the bending edge, and when removed from the contact pin, have second surface areas that can be placed on second areas of the contact pin, by means of which the spring tabs can be pre-tensioned outwards and can be pivoted resiliently around the bending edge, wherein the distance of the first surface areas of the spring tabs from the bending edge is greater than the distance of the second areas from the bending edge.

In particular, this design ensures that the insertion force is considerably lower in relation to the removal force of the socket-type connection contact.

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Because when the socket-like connection contact is plugged onto the contact pin, the first surface area of the spring tabs is engaged, which is at a greater distance from the bending edge of the spring tabs than the second area, the corresponding lever arm is relatively large, which means that the corresponding attachment force is relatively low. When the socket-like connection contact is removed from a contact pin, the second areas of the spring tabs are touched by the corresponding areas of the contact pin and the spring tabs are bent open, whereby the distance between this area of engagement and the bending edge is smaller, so that a smaller lever arm is available for actuation, which leads to considerably higher removal forces.

Furthermore, it is preferably provided that the free ends of the spring tabs are designed as grooves curved radially inwards with respect to the pipe section or the sleeve, wherein the central axis of the grooves runs parallel to the bending edge of the respective spring tab and the free groove leg end forms an insertion bevel for the contact pin.

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This design also means that the insertion forces are significantly lower than the removal forces. It is particularly preferred that the grooves are shaped in an arc to match the circular outer contour of the contact pin.

This allows a larger contact area of the grooves to be achieved with the contact pin.

It is particularly preferred that the curvature of the grooves is formed by beveled surface areas of the spring tabs, the first surface area of which, closest to the bending edge of the spring tab, is directed radially inwards at a flat angle, the following second surface area of which runs at least approximately parallel to the central axis or to the groove base of the locking groove of the contact pin and has a maximum length that corresponds to the width of the groove base, and the following third surface area of which is directed radially outwards at a flat angle.

This has a particularly favourable effect on the ratio of the insertion force and the withdrawal force as described above.

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For the same reason, it is preferably provided that the bend of the first surface area is steeper than that of the third surface area.

This effect is enhanced if the front surface of the free end of each spring tab in the direction of insertion of the contact pin is smooth and the rear surface is designed to increase friction, preferably by means of grooves or ridges that run transversely to the direction of insertion.

To increase friction, it is sufficient if the corresponding surface is roughened. However, it is more advantageous to arrange grooves or striations that run perpendicular to the direction of insertion.

Furthermore, it is preferably provided that the bushing receiving the pipe section or the sleeve consists of a bushing base with a central connection piece and a jacket that can be connected to the latter, wherein the pipe section or the sleeve is arranged with its one end between a radial

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outer surface of the central connector and an inner surface of the bushing jacket surrounding it, whereby the other end of the pipe section or sleeve can be supported on a radially inwardly projecting collar of the bushing jacket in the mouth area of the bushing.

In principle, the design of the bushing is similar to the design according to the state of the art mentioned at the beginning, but with the essential difference that the sleeve with its end at the back in the insertion direction is pressed in between the outer surfaces of the central socket and the bushing jacket.

In this way, a suitable fixation of the tubular section or the sleeve in the bushing is possible.

In some circumstances it may be advantageous if a circumferential annular groove is formed on the central socket of the bushing base, into which one or more molded projections, e.g. in the form of domes of the pipe section or the sleeve, are inserted.

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It is preferably provided that the projections are arranged in the axial longitudinal direction of the spring tabs.

A preferred further development is seen in the fact that the spring tabs are each cut out like a window and have an air gap opposite the sleeve. This design enables clear positional security and guidance within the socket part, since the two end edges of the pipe section or the sleeve are each completely guided and supported on the inner casing of the socket part. The air gap also ensures that no undesirable frictional forces occur when the spring tabs are deflected. In some circumstances, however, it is also advantageous if the spring tabs are formed by slots that are open at the edge towards the mouth side of the socket.

This enables a short design. The pipe section or sleeve can normally have a circular cross-section. However, it is also possible to design this part in cross-section as a regular polygon, for example a hexagon, which allows for a particularly high degree of dimensional accuracy.

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and spring constancy can be achieved in mass production.

Two embodiments of the invention are shown in the drawing and described in more detail below. It shows:

Fig. 1 shows a first embodiment of a socket-like connection contact in a central longitudinal section;

Fig. 2 shows the spring element of the connecting contact in section II-II of Fig. 1;

Fig. 3 a development of the spring element; Fig. 4 the spring element seen in the middle longitudinal section;

Fig. 5 to 8 show a second embodiment in the same view as Fig. 1 to 4.

The drawing shows a socket-like connection contact 1 for spark plug connectors, which with their one

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end can be inserted into a receptacle 2 at the bottom of the socket-like connection contact.

The entire socket-like connection contact is overmolded with plastic compound after completion.

The connection contact 1 has a spring element inserted into its socket and can be releasably plugged onto a contact pin 4 of a spark plug 5 provided with an annular locking groove 3 while pre-tensioning the spring element.

In the exemplary embodiment, the spring element is designed as a longitudinally slotted sleeve 6, wherein the longitudinal slot is designated 7.

Three spring tabs 8 are cut out of the wall of the sleeve 6 and are evenly distributed around the circumference.

Its bending edge 9 runs transversely to the plug axis (central longitudinal axis 10).

When the contact pin 4 is inserted, the free ends 11 of the spring tabs 8 engage in its locking groove 3 under spring preload. In order to achieve in a particularly favourable manner that the push-on force is significantly

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is less than the pull-off force of the contact pin 4, the spring tabs 8, as is particularly illustrated in Figure 5, have first surface areas 13 that can be placed on first areas 12 of the contact pin 4 when plugged onto the contact pin, by means of which the spring tabs 8 can be pre-tensioned radially outwards and can be pivoted resiliently around the bending edge 9.

Furthermore, when the socket is removed from the contact pin 4, second surface areas 15 are provided on the spring tab 8 that can be placed on second areas 14 of the contact pin 4, by means of which the spring tabs 8 can be pre-tensioned outwards and can be pivoted resiliently around the bending edge 9. The distance of the first surface areas 13 of the spring tabs 8 from the bending edge 9 (distance b) is significantly greater than the distance of the second areas 15 from the bending edge 9 (c).

The clamping area of the spring is marked with "a". According to this design, the lever arm "b" when inserting the spark plug contact pin 4 is larger than the lever arm "c" when pulling the contact pin 4 out of the socket, which results in the desired significant

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Difference between insertion force and withdrawal force results.

The free ends 11 of the spring tabs 8 are designed as grooves curved radially inwards with respect to the sleeve 6, where the central axis of the grooves runs parallel to the bending edge of the spring tabs 8 and the free groove leg end 16 forms an insertion bevel for the contact pin 4 when it is inserted. The grooves are adapted to the circular outer contour of the contact pin 4 (arc-shaped at 27). The curvature of the grooves in the embodiment according to Figures 5 to 8 is formed by beveled surface areas of the spring tabs 8, the first surface area of which, closest to the bending edge of the spring tab 8, is directed radially inwards at a flat angle, the following second surface area 18 of which runs at least approximately parallel to the central longitudinal axis 10 or to the groove base of the locking groove of the contact pin 4 and has a maximum length that corresponds to the width of the groove base and the following third surface area of which is directed radially outwards at a flat angle.

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The bend of the first surface area 17 is steeper than that of the third surface area 19. In addition, the surface 19 of the free end of each spring tab 8, which is at the front in the direction of insertion of the contact pin 4, can be smooth and the surface 17 at the back can be roughened to increase friction, with grooves or ridges preferably being formed in this surface, which run transversely to the direction of insertion. The socket that receives the sleeve 6 consists of a socket base 20 with a central connector 21 and a jacket 22 that is press-connected to the latter.

The sleeve 6 can be loosely inserted with play with its end located at the top in drawing figures 1 and 5 between a radial outer surface of the central connector 21 and an inner surface of the bushing jacket 22 surrounding it, whereby the other end of the sleeve 6 can be supported, if necessary with play, on a radially inwardly projecting collar 23 of the bushing jacket 22 in the mouth area of the bushing.

For functionality, an arrangement with play is sufficient, as shown in Fig. 1.

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However, a play-free arrangement is preferred, as shown in Fig. 5, wherein the sleeve 6 is pressed between the corresponding outer surfaces of the parts 21 and 22.

In the embodiment according to Fig. 1, the press connection between the parts 21 and 22 takes place in the area 24.

In addition, a circumferential annular groove can be formed on the bushing base, into which one or more molded projections 26 of the sleeve 6 are inserted in a form-fitting manner.

Preferably, the projections 26 are arranged in the axial longitudinal direction of the spring tabs 8, as can be seen in particular from the figure.

In the embodiment according to Fig. 1 to 4, the spring tabs 8 are each cut out of the sleeve material of the sleeve 6 in the form of a window.

Guide parts of the sleeve 6 are therefore available below and above the spring tab for the purpose of proper guidance and support.

However, this increases the overall length of the component.

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In the embodiment according to Fig. 5 to 8, the spring tabs 8 are formed by slots that are open at the edge towards the mouth side of the socket, whereby the overall length of the sleeve 6 is reduced.

The invention is not limited to the embodiment, but is variable in many ways within the scope of the disclosure.

All new individual and combination features disclosed in the description and/or drawing are considered essential to the invention.

Claims (1)

BREMI 10439/91 Protection claims : 1. Socket-type connection contact for spark plug connectors, wherein the connection contact has a spring element inserted into its socket and can be releasably plugged onto a contact pin of a spark plug provided with an annular locking groove under pre-tension of the spring element, characterized in that that the spring element is designed as a tube section or as a longitudinally slotted sleeve (6), from the wall of which several spring tabs (8) are cut out, preferably distributed substantially evenly around the circumference, the bending edge (9) of which runs transversely to the plug axis (10) (central longitudinal axis) of the connection contact (4) and the free ends (11) of which can be inserted into the locking groove (3) of the contact pin (4) under spring tension. 2. Socket-type connection contact according to claim 1, characterized in that the spring tabs (8) when plugged onto the contact pin (4) at first BREMI 10439/91 Areas (12) of the contact pin (4) have first surface areas (13) that can be applied, by means of which the spring tabs (8) can be pre-tensioned radially outwards and can be pivoted resiliently around the bending edge (9), and when pulled off from the contact pin (4) have second surface areas (15) that can be applied to second areas (14) of the contact pin (4), by means of which the spring tabs (8) can be pre-tensioned outwards and can be pivoted resiliently around the bending edge (9), wherein the distance (b) of the first surface areas (13) of the spring tabs (8) from the bending edge (9) is greater than the distance (c) of the second areas (15) from the bending edge (9). 3. Socket-type connection contact according to claim 1 or 2, characterized in that the free ends of the spring tabs (8) are designed as grooves curved radially inward with respect to the pipe section or the sleeve (6), the central axis of the grooves running parallel to the bending edge (9) of the respective spring tab (8) and the free groove leg end forming an insertion bevel (16) for the contact pin (4). BREMI 10439/91 4. Socket-type connection contact according to one of claims 1 to 3, characterized in that the grooves of the
shaped in an arc shape (at 27) to match the circular outer contour of the contact pin (4). 5. Socket-type connection contact according to one of claims 1 to 4, characterized in that the curvature of the grooves is formed by beveled surface areas of the spring tabs
(8) is formed, the first surface area (17) closest to the bending edge (9) of the spring tab (8) is directed radially inwards at a flat angle, the following second surface area (18) runs at least approximately parallel to the central axis (10) or to the groove base of the locking groove (3) of the contact pin (4) and has a maximum length which corresponds to the width of the
groove base, and whose following third surface area (19) is directed radially outwards at a shallow angle. BREMI 10439/91 6. Socket-type connection contact according to claim 5, characterized in that the bend (17) of the first surface region is steeper than that of the third surface region (19). 7. Socket-type connection contact according to one of claims 1 to 6, characterized in that the front surface (19) of the free end of each spring tab (8) in the insertion direction of the contact pin (4) is smooth and the rear surface (17) is designed to increase friction, preferably by grooves or ridges which run transversely to the insertion direction. . Socket-type connection contact according to one of claims 1 to 7, characterized in that the bushing receiving the pipe section or the sleeve (6) consists of a bushing base (20) with a central connection piece (21) and a jacket (22) connectable to the latter, wherein BREMI 10439/91 the pipe section or the sleeve (6) is inserted with one end between a radially outer surface of the central connector (21) and an inner surface of the bushing jacket (22) surrounding it, wherein the other end of the pipe section or sleeve (6) can be supported on a radially inwardly projecting collar (23) of the bushing jacket (22) in the mouth region of the bushing. 9. Socket-type connection contact according to claim 8, characterized in that a circumferential annular groove (25) is formed on the central connecting piece (21) of the socket base (20), into which one or more molded projections (26) of the pipe section or the sleeve (6) are inserted. 10. Socket-type connection contact according to claim 9, characterized in that the projections (26) are arranged in the axial longitudinal direction of the spring tabs (8). BREMI 10439/91 11. Socket-type connection contact according to one of claims 1 to 10, characterized in that the spring tabs (8) are each cut out like a window. 12. Socket-type connection contact according to one of claims 1 to 10, characterized in that the spring tabs (8) are formed by slots open at the edge towards the mouth side of the socket. DIPL-ING-CONRAD-JOACHIM KOCHLINC PATENT ATTORNEY