Measuring and testing – Vehicle chassis – Steering
Reexamination Certificate
1995-06-26
2001-01-23
McCall, Eric S. (Department: 2855)
Measuring and testing
Vehicle chassis
Steering
C073S116070
Reexamination Certificate
active
06176123
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to a detecting apparatus of engine rotation angle.
BACKGROUND OF THE INVENTION
An electronically controlled automobile engine is generally provided with a sensor for detecting the rotating state of the engine.
As a kind of such sensor, a crank angle sensor for detecting the specific rotating position of the engine crankshaft is disclosed for example in Jikkai Sho. 58- 19532 published in 1983 and Tokkai Sho. 63-183375 published in 1988 by the Japanese Patent Office.
The crank angle sensor detects only a specific rotating position a so called reference position, but it may be desired to detect continuously the rotation angle of the crankshaft in a specific range from the reference position. Such necessity arises, for example, when determining misfiring of engine. In order to determine misfiring in a cylinder, the angular velocity of the crankshaft in the specific range from the reference position corresponding to the cylinder is detected, then the detected angular velocity is compared with the previously detected angular velocity in the same range or with the angular velocity detected in other specific range. When a speed drop more than a predetermined value is found in this comparison, the corresponding cylinder is determined to have misfired.
To obtain an angular velocity, the rotation angle of the crankshaft must be detected continuously, which is realized, for example, by detecting passing of teeth of a ring gear mounted on the engine crankshaft by a magnetic sensor, and counting the number of passing teeth.
The ring gear is a gear for starting up the engine by engaging with a pinion of a starter motor when starting up the engine. The magnetic sensor is provided oppositely to the teeth of the ring gear, detects changes of its own magnetic field by passing of teeth of the ring gear, and outputs a pulse signal. Therefore, by counting the pulses of the signal after output of the reference position signal, the rotation angle of the crankshaft from the reference position is continuously detected.
However, the ring gear is gradually worn by contact with the pinion upon start of engine, and accordingly the output voltage of the magnetic sensor may drop or the output voltage ratio may vary. In such a case, the detection precision of the rotation angle may also decrease.
SUMMARY OF THE INVENTION
It is therefore a primary object of this invention to enhance the durability of such a rotation angle detecting apparatus that is applied to the ring gear of an engine.
It is another object of this invention to enhance the detection precision of the rotation angle detecting apparatus.
In order to achieve the above objects, this invention provides an apparatus for continuously detecting a rotation angle in a specific range of a crankshaft of such an engine that has a piston reciprocating between a top dead center and bottom dead center. The apparatus comprises a ring gear having teeth and coupled with the crankshaft, a starter motor for rotating the ring gear, a starter pinion coupled with the motor and having teeth to be engaged with the ring gear teeth when starting up the engine, a magnetic sensor for outputting a signal according to the passing of teeth in a specific range of the ring gear which is set so as not to overlap with a wear region of the ring gear teeth which is worn due to engagement with the pinion, and a mechanism for detecting a rotation angle of the crankshaft based on the signal.
The wear region is either a region to be engaged with the teeth of the pinion at a point where a rotating resistance of the engine becomes large when starting up the engine, or a region to be engaged with the teeth of the pinion when starting up the engine.
In the latter case, the magnetic sensor is preferably installed at either a first position slightly rotated from the position of the starter motor in the rotating direction of the ring gear, or a second position rotated 180 degrees around the center of the ring gear from the first position.
It is also preferable that the apparatus further comprises a sensor for outputting a reference signal corresponding to a specific rotation position of the crankshaft and the detecting mechanism starts detecting the rotation angle with the reference signal.
It is also preferable that the apparatus further comprises a mechanism for detecting a rotation speed of the crankshaft from the signal output by the magnetic sensor.
The details as well as other features and advantages of this invention are set forth in the remainder of the specification and are shown in the accompanying drawings.
REFERENCES:
patent: 4274141 (1981-06-01), Tokuda et al.
patent: 4302815 (1981-11-01), Tedeschi et al.
patent: 4425812 (1984-01-01), Williams
patent: 4700305 (1987-10-01), Lotterbach et al.
patent: 4707791 (1987-11-01), Hmelovsky et al.
patent: 4782692 (1988-11-01), Peden et al.
patent: 5485374 (1996-01-01), Takaku et al.
patent: 58-19532 (1983-02-01), None
patent: 63-183375 (1988-11-01), None
McCall Eric S.
McDermott & Will & Emery
Nissan Motor Co,. Ltd.
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