Seal for a joint or juncture – Seal between relatively movable parts – Relatively rotatable radially extending sealing face member
Patent
1990-04-12
1991-11-19
Cuchlinski, Jr., William A.
Seal for a joint or juncture
Seal between relatively movable parts
Relatively rotatable radially extending sealing face member
73 35, 277235B, 324464, G01L 2223, F02F 1100, F16J 1506
Patent
active
050660233
DESCRIPTION:
BRIEF SUMMARY
The present invention relates to an ionisation sensor for a combustion chamber of a spark ignited engine.
It is known to use ionisation sensors in a combustion chamber in order to obtain a measure of the flame propagation speed and to detect knocking, the output of the sensor being used as a control parameter in certain engine management systems. The sensor detects the time of arrival of the flame by the increased level of ionisation in the flame. The ionisation is measured by sensing the current flowing between a pair of electrodes which are isolated from one another and across which a potential is applied.
Hitherto, ionisation sensors have comprised an electrode mounted on an insulating body which is screwed into the cylinder at a distance from the spark plug. Apart from requiring an additional access hole in the cylinder body or cylinder head, the electrode was small and the resultant signal had a poor signal to noise ratio.
With a view to mitigating the foregoing disadvantages, the present invention provides a gasket for sealing between an engine block and a cylinder head, characterised by an electrically conductive surface portion which, in use, is electrically insulated from the cylinder head and from the engine block so that it may serve as an electrode of an ionisation sensor.
Because the cylinder head gasket serves as the ionisation sensor, there is no need to form any special access holes in the cylinder head. Also, it is possible in this way to achieve a large area electrode without altering the geometry of the combustion chamber. The large area of the electrode improves signal to noise ratio and avoids errors caused by local anomalies.
A cylinder head gasket serves many sealing functions in that it not only prevents escapes of gases under high pressure from the combustion chamber but also seals various low pressure passages for oil and water. It is not essential, however, for the same gasket to perform all these functions and instead it is preferred to provide an annular gasket for each combustion chamber to effect a high pressure seal and to provide a separate softer gasket to seal the water and oil passages.
In this case, the electrical lead connected to the sensing electrode portion of the annular gasket be passed through a channel recessed into the cylinder head or the cylinder block and covered by the soft gasket.
Preferably, the annular gasket comprises a five layer sandwich comprising two outer layers of soft metal capable of deformation under pressure to effect a gas tight seal with the block and the cylinder head, a central core of electrically conductive material to serve as an ionisation electrode and two layers of ceramic material insulating the central core from the two outer layers.
The central core may conveniently comprise a collapsible hollow box structure having a resilient filling, which is capable of taking up any tolerances in the cylinder head and cylinder block.
The radially inner surface of the gasket may be coated in selected regions with a ceramic layer so that only the uncoated parts of the surface of the gasket may act as a sensing electrode. The ionisation sensing portions of the gasket may in this way be positioned as desired relative to the spark plug.
The invention will now be described further, by way of example, with reference to the accompanying drawings, in which:
FIG. 1 shows a partial section through combustion chamber in which the cylinder head gasket is designed to act as an electrode of an ionisation sensor,
FIG. 2 shows part of FIG. 1 drawn to an enlarged scale, and
FIG. 3 is a schematic representation showing the ionisation sensors of a four cylinder engine.
Figure shows a section through a combustion chamber of an internal combustion engine. The walls of the combustion chamber 20 are defined by a piston 10, a cylinder 12, a cylinder head 14 and a head gasket 16. The drawing also shows an inlet poppet valve 24 closing off an inlet port 22 and a spark plug 28. The cylinder head and engine block may be generally conventional and they need not therefore b
REFERENCES:
patent: 2753199 (1956-07-01), Victor
patent: 3873102 (1975-03-01), Lotze et al.
patent: 4397176 (1983-08-01), Rohde et al.
patent: 4433198 (1984-02-01), Berner et al.
patent: 4686861 (1987-08-01), Morii
patent: 4743421 (1988-05-01), McDowell et al.
Cuchlinski Jr. William A.
Cummings Scott W.
Drouillard Jerome R.
Ford Motor Company
Sadler Clifford L.
LandOfFree
Ionization sensor does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Ionization sensor, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Ionization sensor will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-1365414