Electrical generator or motor structure – Dynamoelectric – Oscillating
Reexamination Certificate
1997-11-05
2001-05-08
Enad, Elvin (Department: 2834)
Electrical generator or motor structure
Dynamoelectric
Oscillating
C310S012060, C310S014000, C310S015000, C310S017000
Reexamination Certificate
active
06229231
ABSTRACT:
BACKGROUND OF THE INVENTION
The invention relates to a reciprocation motor, and, more particularly, to means capable of detecting the rotation angle of a reciprocating rotor accurately.
A reciprocation motor is already known in which control of the rotation angle of a rotor can be freely made. A transverse sectional view of this prior art reciprocation motor is shown in FIG.
14
. Rotor
1
is a cylindrically-shaped magnet having two poles spaced apart in a radial direction thereof and comprises a pair of half-cylindrical magnets. One end of the magnet is formed so as to be an N pole, and other end is formed so as to be an S pole.
FIG. 15
shows a view where the reciprocation motor of
FIG. 14
is spread out in a plan view. Driving coils
5
a
and
5
b
are wound equally on coil board
3
. Magnetic sensor
7
is centrally fixed inside the driving coil
5
b
on coil board
3
. Magnetic sensor
7
may comprise, for example, a Hall element capable of converting magnetic flux to voltage.
Next, the operation will be described. When current flows through driving coils
5
a
and
5
b,
torque occurs between driving coils
5
a,
5
b
and the magnet of rotor
1
. When current is maintained at a predetermined value, rotor
1
stops. When driving coils
5
a
and
5
b
are connected in series, and alternating current flows through time, it is possible to cause reciprocating motion through 180 degrees. Although two driving coils
5
a
and
5
b
are shown in
FIG. 15
, the reciprocating range can be determined freely using one or plural driving coils. When rotor
1
reciprocates as shown in
FIG. 16
, an output shown in
FIG. 17
is obtained from magnetic sensor
7
. It is possible to obtain an output from magnetic sensor
7
nearly in proportion to the magnetic field. Therefore, it is possible to control the rotor
1
to stop at a desired position by adjusting the current of driving coil
5
so as to make the output signal from magnetic sensor
7
a predetermined value. It is possible to control reciprocating motion through a desired angular range by inputting an alternating signal from an oscillator, not shown, to driving coil
5
.
Thus, by forming magnetic sensor
7
centrally at the inside of driving coil
5
b
this makes it possible to control current of the driving coil and to detect the position (angle) of rotor
1
.
The prior art reciprocating motor is influenced by not only magnetic flux of magnet of rotor
1
but also magnetic flux of current flowing through driving coil
5
b
because the magnetic sensor
7
is formed centrally inside driving coil
5
b.
Therefore, there is a possibility that the position detecting accuracy of the rotor
1
is diminished.
In order to solve the prior art problem noted above, an object of the present invention is to provide a reciprocating motor capable of detecting the rotation angle of the rotor accurately.
SUMMARY OF THE INVENTION
The present invention comprises a reciprocating motor having a rotor having a magnet of two poles in the radial direction; at least one driving coil for reciprocating the rotor through a predetermined angular range, said driving coil being formed around said rotor leaving a small gap between the rotor and the driving coil; and one or more sensors for sensing at least one of the intensity of a magnetic field generated by the driving coil and the rotation angle of said rotor, being formed outside of said driving coil. The sensor(s) are formed outside of, i.e., disposed so as to be spaced apart from the driving coil because magnetic flux density produced by the driving coil is smaller outside than inside the driving coil. Therefore, the influence on the sensor(s) of current flowing through the driving coil is greatly reduced, and the magnetic flux of the magnet of the rotor is detected accurately. High detecting accuracy of the magnetic flux of the rotor causes high accuracy detection of the rotation angle of the rotor. As used herein, the term “outside of the driving coil” means spaced apart from the driving coil in any direction, such as up or down, right left of the driving coil.
Although the rotation angle of the rotor can be detected accurately avoiding the influence of current flowing through the driving coil, preferably at least one of said one or more sensors is formed at a center position along the length of each said driving coil in circumferential direction or in the main shaft direction of said each driving coil.
The sensor formed at the center position along the length of each said driving coil in the circumferential direction or in the main shaft direction makes it possible to control reciprocation after setting beforehand, except if the electric angle is near ±90 degrees (as used here, the “electric angle” is taken as zero degrees when the border of N and S poles of the rotor is at the same angle as the sensor).
Although the sensor(s) can be set outside of the driving coil and spaced far from the driving coil to avoid the influence of current flowing through the driving coil as much as possible, said sensor can alternatively be formed close to said driving coils.
The shaft length of the rotor of the above construction is shortest in the case that the sensor is formed above or under the driving coil.
Further, the present invention has a rotor having a magnet of at least two poles spaced apart in the radial direction, the rotor being formed so as to rotate freely; at least two driving coils for reciprocating said rotor through a predetermined angle range, the driving coils being formed around the rotor such that a small gap exists between the rotor and the driving coil at a predetermined interval; and a sensing means for sensing a rotation angle of said rotor, the sensing means being formed at one of a first area located between the driving coils along the circumferential direction of the rotor and a second area axially spaced from the first area.
The reason for forming the sensing means for sensing the rotation angle of the rotor at either of a first area between the driving coils along the circumferential direction of the rotor and a second area axially spaced from the first area is that the influence of the magnetic flux caused by current flowing through the driving coils is greatly reduced.
Moreover, the detecting means in a preferred embodiment, comprises a magnetic sensor formed at a position shifted by a predetermined angle from a center along the length of said driving coils in the circumferential direction to a direction of rotation of said rotor in said second area, and a detecting magnet formed at said rotor having at least two poles in the radial direction for the magnetic sensor to detect the rotation angle of said rotor, wherein said detecting magnet is formed at said rotor so that the border portion of poles of the detecting magnet is shifted said predetermined angle along the rotation direction of said rotor standardizing the border portion of poles of said magnet formed at said rotor.
Because of that, reducing influence to the magnetic flux caused by current flowing through the driving coils, the rotation angle of the rotor is detected accurately, and it is possible to control similarly as in the past.
REFERENCES:
patent: 4463300 (1984-07-01), Mayne et al.
patent: 4649925 (1987-03-01), Dow et al.
patent: 4913155 (1990-04-01), Dow et al.
patent: 5038062 (1991-08-01), Shiraki
patent: 5161361 (1992-11-01), Talley et al.
patent: 5284411 (1994-02-01), Enomoto et al.
patent: 5338121 (1994-08-01), Kobayashi et al.
patent: 5696413 (1997-12-01), Woodbridge et al.
Ishida Takashi
Ooki Shigeru
Adams & Wilks
Enad Elvin
Seiko Seiki Kabushiki Kaisha
LandOfFree
Reciprocating motor having controllable rotor position does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Reciprocating motor having controllable rotor position, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Reciprocating motor having controllable rotor position will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2531529