Connection plug

Described is a connection plug for connecting an ignition coil to a spark plug, comprising an electric line that has a first end for contacting an ignition coil and a second end for contacting the spark plug, a protective hose that surrounds the electric line, a protective pipe that surrounds the protective hose, wherein the protective hose is retained in the protective pipe in a positive-locking manner. The protective pipe has latching recesses at its ignition coil end, into which latching projections of the protective hose engage.

RELATED APPLICATIONS

This application claims priority to DE 10 2017 101 892.1, filed on Jan. 31, 2017, and DE 10 2017 102 575.8, filed on Feb. 9, 2017, both of which are hereby incorporated herein by reference in their entirety.

BACKGROUND

This disclosure relates to a connection plug for connecting an ignition coil to a spark plug.

The connection plug known from DE 10 2011 082 231 A1 has an electric line in the form of a helical spring that is surrounded by a protective hose. The protective hose is surrounded by a protective pipe which, at an end portion towards the spark plug, has an inwardly oriented projection that engages in a groove on the outside of the protective hose so that the protective hose is retained in the protective pipe in a positive-locking manner. The groove at the outside of the protective hose is formed by two radial circumferential projections on the inside of the protective hose which are arranged at an axial distance from one another. For retaining the protective hose at the spark plug there is provided an additional pin that is pressed into a corresponding through-hole in the protective hose and the protective pipe and thus achieves a locking between the protective hose and the protective pipe. If the protective hose needs to be pulled out of the protective pipe, the pressed-in pin first has to be removed.

A positive-locking connection between the protective hose and the protective pipe, on the one hand, has to be flexible enough so that the protective hose can be inserted into the protective pipe and, on the other hand, has to generate enough retention force so that the protective hose cannot unintentionally be pulled out of the protective pipe.

SUMMARY

This disclosure teaches a connection plug that allows for a reliable positive locking between protective hose and protective pipe, which can easily be opened if needed.

According to this disclosure, the protective pipe has latching recesses at its end towards the spark plug into which latching projections of the protective hose engage. In this manner, the latching can be performed more easily and, if needed, can be released again when the connection plug is connected to an ignition coil or detached from an ignition coil.

An advantageous refinement of this disclosure provides that the latching recesses are formed as through-holes. This feature has the advantage that the latching between protective pipe and protective hose can be easily released, if needed. Namely, when the connection plug is removed from the ignition coil, pressure can be applied on the latching projections of the protective hose through the holes of the protective pipe so that the latching projections of the protective hose disengage from the latching recesses of the protective pipe. Preferably, the latching recesses are formed as elongated through-holes.

Another advantageous refinement of this disclosure provides that the latching recesses are formed on opposite supporting arms of the protective pipe. Then, the protective hose can be unlocked simply by pressing.

The supporting arms may, for example, extend from a shoulder formed on the protective pipe. In this manner, the shoulder can advantageously form an unplugging aid. If it is desired to unplug the connection plug from the spark plug shaft of an engine, the shoulders of the supporting arms form a grip by means of which this can be easily done.

Another advantageous refinement of this disclosure provides that the latching projections are arranged on an end portion of the protective hose so that a high-voltage terminal of an ignition coil is situated between the latching projections when the connection plug is attached onto the high-voltage terminal of the ignition coil. In this manner, the engagement of the latching projections in the latching recesses of the protective pipe is secured by the high-voltage terminal of the ignition coil. When the connection plug is attached onto the high-voltage terminal of the ignition coil, the high-voltage terminal of the ignition coil thus prevents the latching projections from being pushed inwards and disengaged from the latching recesses of the protective pipe. Moreover, when attaching the connection plug, the latching projections can advantageously be pushed into the latching recesses of the protective pipe by attaching the protective hose onto the high-voltage terminal of the ignition coil.

Another advantageous refinement of this disclosure provides that the latching projections of the protective hose have an insertion chamfer. In this manner, inserting the protective hose into the protective pipe can be facilitated.

Another advantageous refinement of this disclosure provides that the end faces of the latching projections on the side towards the ignition coil are inclined walls that form an undercut. In this manner, the pull-out force of the protective hose can be increased when the latching projections of the protective hose engage in the latching recesses of the protective pipe.

DESCRIPTION

The connection plug6illustrated in the figures is configured for connecting an ignition coil1to a spark plug of an internal combustion engine. The connection plug6includes an electric line8that has a first end for contacting the ignition coil1and a second end for contacting the spark plug. The electric line8can be formed as a helical compression spring, for example. The electrical line8is surrounded by a protective hose2which can be made from silicone, for example. The protective hose2is surrounded by a protective pipe3which can be made from plastics or metal, for example.

The protective hose2is retained in the protective pipe3in a positive-locking manner by the latching projections4of the protective hose2engaging in the latching recesses5of the protective pipe3. The latching recesses5of the protective pipe3are provided at the connection plug's6end on the side configured for contacting the ignition coil, for example in the form of through-holes. In the embodiment shown, the latching recesses5are formed as elongated through-holes, for example.

The latching recesses5of the protective pipe5are provided in supporting arms10which extend from shoulders9formed on the protective pipe3. The shoulder9forms an unplugging aid and enables a good grip of the protective pipe3so that the latter can be easily pulled out of the spark plug shaft of an engine, if needed. In the embodiment shown, there are exactly two supporting arms10which oppose one another. At their free end on the side towards the ignition coil there is an insertion chamfer11. The insertion chamfer11facilitates inserting the protective hose2into the protective pipe3when assembling the connection plug6.

The latching projections4are formed integrally with the protective hose2. It is advantageous here that the latching projections4are arranged on an end portion of the protective hose2so that a high-voltage terminal7of the ignition coil7is situated between the latching projections4, when the connection plug6is attached onto the ignition coil1. The high-voltage terminal7then prevents the latching projections4from being pushed inwards and disengaging from the latching recesses5of the protective pipe3.

When the connection plug6is not attached on a high-voltage terminal7, the latching projections4can easily be pushed inwards by hand so that the positive locking between the protective pipe3and the protective hose2can be released if needed. Then, when the latching projections4of the protective hose2are pushed inwards, the protective hose2can be pulled out of the protective hose3without any problem. In addition, the protective hose2may have projections and/or recesses in an inner surface for a positive-locking connection with recesses and/or projections on the outside of a high-voltage terminal7.

FIG. 5shows in a sectional detailed view another embodiment that differs from the above explained embodiment in that the latching projections4have insertion chamfers12so as to facilitate the insertion of the protective hose2into the protective pipe3. Moreover, the end faces of the latching projections4on the side towards the ignition coil can be provided as inclined walls13which form an undercut. This undercut increases the pull-out forces of the protective hose when the latching projections4engage in the latching recesses5.

REFERENCE LIST