Electricity: measuring and testing – Electrical speed measuring – Including speed-related frequency generator
Reexamination Certificate
2000-09-29
2002-12-10
Lefkowitz, Edward (Department: 2862)
Electricity: measuring and testing
Electrical speed measuring
Including speed-related frequency generator
C324S160000
Reexamination Certificate
active
06492805
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a wheel speed detecting device which detects the rotational speed of a wheel.
2. Description of Related Art
Motorcycles adopting, for instance, an Antilock Brake System (ABS) are equipped with a wheel speed detecting device for detecting the rotational speed of front and rear wheels. As a background art wheel speed detecting device, the “Wheel Speed Detecting Device in Motorcycles” disclosed in Japanese Patent Laid-Open No. H8-133154 has been known. This background art will be explained in detail by referring to FIG.
18
.
FIG. 18
is a side view of a background art wheel speed detecting device. The wheel speed detecting device mounted on the rear wheel of a motorcycle will be explained below.
In a wheel speed detecting device
150
, a sensor ring (hereinafter referred to as the “pulsar ring”)
153
is attached on a spoke portion
152
of a rear wheel
151
. A pulse counting sensor
156
(e.g., an electromagnetic rotary sensor) is attached on a swing arm
155
which supports the rear wheel
151
, oppositely to teeth
154
of the pulsar ring
153
.
According to the wheel speed detecting device
150
, with the rotation of the rear wheel
151
, the pulsar ring
153
rotates together with the rear wheel
151
, while the teeth
154
of the pulsar ring
153
pass the pulse counting sensor
156
. The pulse counting sensor
156
counts the teeth
154
that have passed thereby, thus detecting the wheel speed of the rear wheel
151
(the rotational speed of the rear wheel
151
).
To improve the detection accuracy of the teeth
154
by the pulse counting sensor
156
, it is desirable to mount the pulse counting sensor
156
close to the teeth
154
. In order to mount the pulse counting sensor
156
close to the teeth
154
, it is necessary to set the flatness of the pulsar ring
153
(particularly, the teeth
154
).
If the flatness of the pulsar ring
153
exceeds a permissible range, unevenness of the pulsar ring
153
increases. It is therefore necessary set the pulse counting sensor
156
apart from the teeth
154
with the unevenness taken into account. Accordingly, it is difficult to improve the detection accuracy of the teeth
154
by the pulse counting sensor
156
.
The teeth
154
of the pulsar ring
153
, therefore, have been formed by a cutting process to set the flatness of the pulsar ring
153
(especially the teeth
154
) within the permissible range. This processing of the pulsar ring
153
requires time and labor, thus increasing the cost.
Forming the pulsar ring
153
by pressing has also been considered. However, since the teeth
154
are relatively long and slender, if processed by pressing, the teeth
154
of the pulsar ring
153
will be subjected to warpage.
Therefore, it is necessary to correct the warpage of the teeth
154
after pressing the pulsar ring
153
. This also increases the time and labor, thus increasing cost.
It has therefore been desired to put into practice a wheel speed detecting device capable of enhancing the detecting accuracy and lowering cost.
SUMMARY OF THE INVENTION
It is therefore an object of the present invention to provide a device which can enhance the detecting accuracy of a wheel speed detecting device and lower the cost.
In view of the above-described problems, the wheel speed detecting device according to a first aspect of the present invention comprises a pulsar ring attached on the wheel side and a pulse counting sensor attached on the vehicle body side. The pulsar ring comprises a disc, and pulse detecting holes or pulse detecting recesses are provided at a predetermined pitch on a pitch circle drawn in a radially inward circumferential position spaced at a distance from an outer edge of the disc.
The pulse detecting holes are opened at a position on the center side, spaced from an outer edge of the pulsar ring, whereby the outer edge of the pulsar ring can remain in a circular shape. Therefore, it is possible to reduce warpage of the pulsar ring at the outer edge if the pulse detecting holes are formed by pressing. Furthermore, the flatness of the pulsar ring can be held within the permissible range.
According to a second aspect of the present invention, when the disc has a sensing surface on the side directed toward the pulse counting sensor, a stiffening rib is provided in the vicinity of, or on the back side of, the sensing surface.
The sensing surface can be increased in rigidity by providing the stiffening rib in the vicinity of, or on the back side of, the sensing surface. Therefore, if the pulsar ring has a reduced plate thickness, it is possible to ensure the flatness of the sensing surface within the permissible range, while enabling a reduction in weight of the pulsar.
A third aspect of the present invention is characterized in that the stiffening rib is provided along the sensing surface, and the height of this stiffening rib is set larger than the clearance from the sensing surface to the pulse counting sensor.
The stiffening rib is provided along the sensing surface and the height of this stiffening rib is increased larger than the clearance from the sensing surface to the pulse counting sensor. Therefore, it is possible to cover the clearance between the sensing surface and the pulse counting sensor with the stiffening rib, the stiffening rib being usable as a protective cover. Therefore, the clearance between the sensing surface and the pulse counting sensor is protected by the stiffening rib, so that the clearance can be prevented from catching a flying substance such as a flying rock.
Furthermore, since the stiffening rib is usable as a protective cover, no individual protective cover is needed, thereby preventing an increase in the number of components. Accordingly, the time and effort required to install a protective cover can be dispensed with.
In a fourth aspect of the present invention, the stiffening rib is formed by bending the outer edge of the disc.
With this construction, the wheel speed detecting device can be improved in quality by increasing the rigidity of the pulsar ring with the outer edge of the disc being bent.
Furthermore, a pulsar ring of predetermined thickness can be obtained with a decrease in weight, making it possible to decrease cost and to improve vehicle performance.
A fifth aspect of the present invention is characterized in that the pulsar ring is prepared from a pressed part with punched pulse detecting holes, and one or both sides of the pulsar ring which faces toward a punch is called the first side and the other is the second side. Furthermore, the pulsar ring is attached so that the second surface faces the pulse counting sensor.
When the pulse detecting hole is punched from the first side through to the second side, the edge of the hole in the first side becomes round, while the hole in the second side has a sharp edge.
In the fifth aspect of the present invention, the pulsar ring is attached with the second side having the sharp-edge holes directed toward the pulse counting sensor.
By using the pulsar ring having sharp-edge holes, the sensing performance of the pulse counting sensor can be improved.
Further scope of applicability of the present invention will become apparent from the detailed description given hereinafter. However, it should be understood that the detailed description and specific examples, while indicating preferred embodiments of the invention, are given by way of illustration only, since various changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art from this detailed description.
REFERENCES:
patent: 3792460 (1974-02-01), Ratz
patent: 4740905 (1988-04-01), Murkami et al.
patent: 5027303 (1991-06-01), Witte
patent: 5257540 (1993-11-01), Bower et al.
patent: 5480348 (1996-01-01), Mazur et al.
patent: 6232767 (2001-05-01), Kawase et al.
patent: 8133154 (1996-05-01), None
Igarashi Makoto
Wakabayashi Takeshi
Honda Giken Kogyo Kabushiki Kaisha
Lefkowitz Edward
Zaveri Subhash
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