Geometrical instruments
Patent
1985-04-02
1986-11-11
Weidenfeld, Gil
Geometrical instruments
339149S, 339213S, 174138S, H01R 1344
Patent
active
046218815
DESCRIPTION:
BRIEF SUMMARY
The present invention relates to a connection device in an ignition system for transferring high-tension current to the spark plugs of an internal combustion engine, each connection device including a comparatively rigid outer sleeve intended to surround the upper portion of a spark plug, to obtain conductive communication with a central electrode of the spark plug via a contact means disposed in the connection device.
It is already known to form a connection device between a spark plug and an ignition cable as a rigid sleeve which is thrust over the upper portion of the spark plug, i.e. the spark plug insulator, a spring arranged in the sleeve being caused to snap round the outer end of the central electrode of the spark plug. There is thus obtained contact between the electrode and a contact tab at the bottom of the sleeve, this tab being in conductive communication with the ignition cable. In such a case, there is a certain gap between the spark plug and the sleeve, resulting in that dirt and moisture can get in and negatively affect the transmission of high-tension current to the spark plug.
With the aim of preventing this disadvantage, it is known to form the sleeve surrounding the spark plug from an elastic material which tightly surrounds the spark plug when the sleeve is thrust over it. Such an elastic sleeve is difficult to remove from the spark plug, however, since the grip appears to increase with increased application of force. There is thus required a considerable force to remove the connection device.
The present invention has the task of implementing a connection device for ignition systems, which allows simple handling and reliable voltage transmission in practical use. To this end, the inventive connection device includes an elastic inner sleeve enclosed by the outer sleeve, the inner sleeve being adapted to sit tightly round the upper portion of the spark plug when the connection device is fitted thereto. There is thus formed a space for radial expansion of the inner sleeve between the outer sleeve and the inner sleeve, and the invention is characterized by the lower portions of the outer and inner sleeves including portions coacting for force transfer between the sleeves, whereby for an upwardly directed force on a connection device fitted to a spark plug, force is transferred to the inner sleeve and causes it to expand radially so that its grip round the plug decreases.
The tendency mentioned in the introduction for the sleeve to more tightly grip round the spark plug when the connection device is removed, is thus prevented by a connection device in accordance with the present invention. With the inventive implementation, the outer sleeve acts on the elastic inner sleeve with a force from below and outwards, thereby limiting the ability of the inner sleeve to stretch because of friction forces relative the spark plug. This means that the removal force can be kept at a suitably low level.
In a preferred embodiment of the invention, the outer sleeve is formed at its lower end with a flange directed radially inwardly, this flange coacting axially with a radially outwardly directed flange on the lower end of the inner sleeve when the connection device is to be removed from the spark plug.
Further distinguishing features of the invention are disclosed in the appended claims and following description of a preferred embodiment of the invention. The description is made with reference to accompanying figures, of which
FIG. 1 is a longitudinal section through an inventive connection device, and
FIG. 2 illustrates the connection device fitted to a spark plug.
The exemplified connection device is included in an ignition unit 1 of the principal kind which is explained in detail in our Swedish Patent Application No. 8204248-2. In the ignition unit 1 there are a plurality of connection devices 5, corresponding to the number of spark plugs 3 in the engine in question. Each connection device 5 is connected to a common upper part 4 of the ignition unit. The ignition unit 1 is rigidly mounted on the engin
REFERENCES:
patent: 2113735 (1938-04-01), Mascuch
patent: 3128139 (1964-04-01), Estes
patent: 4221452 (1980-09-01), Remington
Johansson Sven H.
Nytomt Jan G.
Kline Thomas M.
Saab-Scania Aktiebolag
Weidenfeld Gil
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