Electricity: measuring and testing – Magnetic – Displacement
Reexamination Certificate
1999-02-24
2001-12-11
Patidar, Jay (Department: 2862)
Electricity: measuring and testing
Magnetic
Displacement
C324S207250, C324S174000, C335S284000, C029S592100
Reexamination Certificate
active
06329814
ABSTRACT:
BACKGROUND OF THE INVENTION
FIELD OF THE INVENTION
The present invention relates generally to the field of a rotation detector for detecting the number of revolutions or the speed of rotation, such as a rotation detecting apparatus that is specifically intended for use in detecting the number of revolutions or the speed of rotation for wheels on an automotive vehicle. More particularly, the present invention relates to a tone wheel that may be included in such rotation detecting apparatus together with a rotation sensor for detecting the number of revolutions, wherein the tone wheel is provided for enhancing the sensing ability of the rotation sensor, or the rotation detecting apparatus incorporating the rotation sensor, to detect the number of revolutions or the speed of rotation with higher precision.
Typically, the rotation detecting apparatus of the type described above is mounted on an automobile vehicle so that it can flexibly control the vehicle safety driving mechanism, such as the antilock braking system, the traction control system, the stability control system and the like, which is also installed on the automotive vehicle. Specifically, this rotation detecting apparatus is located on the hub flange and the like in the vehicle's suspension system, and is used for detecting the actual number of revolutions/the speed of rotation for the wheels. When there is any difference in the number of revolutions/the speed of rotation between each of the front wheels and/or between each of the rear wheels that may be determined from the actual number of revolutions/the speed of rotation thus detected, the vehicle driving system or the braking system may be turned on or off, thereby controlling the behavior of the vehicle. This is to ensure that the vehicle can be running with safety in case any emergency situation should occur.
Typically, the rotation detecting apparatus is constructed by incorporating the tone wheel and the rotation sensor therein, as described below in detail. Generally, the tone wheel includes a seal having a flange extending radially and a radial annular ring formed by the flange. The radial annular ring is made of any magnetizable material and magnetized. Within the rotation detecting apparatus, the rotation sensor is located in proximity to the magnetized annular ring of the tone wheel, so that it can detect the number of revolutions/the speed of rotation in response to a pulse from the magnetized annular ring that represents the actual number of revolutions/speed of rotation.
DESCRIPTION OF THE PRIOR ART
A tone wheel that is employed in the conventional rotation detecting apparatus mounted on the automobile for detecting the number of revolutions/the speed of rotation includes the radial annular ring formed by the flange of the seal as described above, and has the following disadvantages:
Firstly, when the tone wheel is mounted within the rotation detecting apparatus, the physical space that remains to be available within the rotation detecting apparatus is very small, and only exists on the lateral sides of the tone wheel. This space must be reserved for the rotation sensor which should be located in proximity to the radial annular ring. However, the space that remains to be available for the rotation sensor is restricted. In fact, the space that can be used for mounting both the tone wheel and the rotation sensor within the rotation detecting apparatus is not large enough, so that it is very difficult to mount the tone wheel and the rotation sensor within the rotation detecting apparatus. Thus, detecting the number of revolutions/speed of rotations by the rotation sensor must be performed in such restricted physical space that exists on the lateral sides of the tone wheel.
Secondly, in the before described tone wheel, the area on which the magnetizing is applied is small and limited. That is to say, the radial annular ring formed on the flange in the seal is magnetized as the before described, and the magnetized radial annular ring has the alternating S and N or N and S polarities by the magnetizing for radiating a pulse to the rotation sensor. In this case, the radial annular ring was formed on the flange, so that the area of the radial annular ring is small and limited. Thereby the area on which the magnetizing is applied is small and limited. This prevents the rotation detecting apparatus or specifically the rotation sensor therein, from detecting the actual number of revolutions/the speed of rotation with the high accuracy or precision is required.
In order to address the particular problems mentioned above, a solution was proposed which allows for the space that is large enough to accommodate both the tone wheel and the rotation sensor within the rotation detecting apparatus. This also allows for the larger area of the tone wheel on which it can be magnetized. The construction shown in
FIG. 4
represents one of such tone wheels according to this prior proposed solution.
Referring to
FIG. 4
, the tone wheel is shaped into a cylindrical form, and comprises a cylindrically shaped ring
2
tightly fitted into the bearing unit
1
, and a cylindrically shaped magnetic pole region
3
in intimate contact with the inner circumferential surface of the cylindrically shaped ring
2
. The cylindrical magnetic pole region
3
may be magnetized so that it can carry the alternating S and N polarity pattern along the circumferential direction of the inner circumferential surface. A cylindrical tone wheel comprising a cylindrical ring
2
and a cylindrical multipole magnetic region
3
is thus provided.
As the tone wheel is shaped like the cylindrical form as described above and shown in
FIG. 4
, it may provide the larger area on which the tone wheel can be magnetized, and may also provide the large free space in the diametrical direction of the tone wheel (on the inner side of the inner circumferential surface of the cylindrical magnetic pole region
3
), namely, not on the lateral sides of the tone wheel, where the rotation sensor can be disposed The rotation detecting apparatus is thus completed.
As the method of magnetizing the cylindrical magnetic pole region
3
of the tone wheel shown in
FIG. 4
, the following method was proposed. According to this method, as shown in
FIG. 4
, a column-like magnetizing yoke
4
that produces the alternating S and N polarities along the circumferential direction of the outer circumferential wall is inserted into the inner circumferential side of the cylindrical magnetic pole region
3
as shown by an arrow
9
, and the outer circumferential wall of the column-like magnetizing yoke
4
and the corresponding inner circumferential side of the cylindrical magnetic pole region
3
are brought closer to each other so that the entire inner circumferential side of the cylindrical magnetic pole region
3
can be magnetized in the alternating N and S polarity pattern at the same time.
It should be noted, however, that when the entire inner circumferential side of the cylindrical magnetic pole region
3
of the tone wheel is to be magnetized at the same time as the before described and shown in
FIG. 4
, it is more likely that the inner circumferential side of the cylindrical magnetic pole region
3
might be magnetized in the irregular alternating N and S polarity pattern if the gap between the inner circumferential side of the cylindrical magnetic pole region
3
and the outer circumferential wall of the column-like magnetizing yoke
4
is not uniform along the outer circumferential wall of the yoke
4
.
The column-like magnetizing yoke
4
is usually formed into a smaller diameter in order to facilitate the insertion of the yoke
4
into the inner circumferential side of the cylindrical magnetic pole region
3
, as shown by an arrow
9
(FIG.
4
). For this reason, it is more likely that the column-like magnetizing yoke
4
might deviate from the center when it is inserted into the space inside the inner circumferential side of the cylindrical magnetic pole region
3
, which would cause the gap between the inner circumferen
Ichiman Shinzaburo
Mizuta Hideo
Patidar Jay
Uchiyama Manufacturing Corp.
Wenderoth , Lind & Ponack, L.L.P.
LandOfFree
Tone wheel and method of magnetizing the same and method of... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Tone wheel and method of magnetizing the same and method of..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Tone wheel and method of magnetizing the same and method of... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2571018