Electrical generator or motor structure – Dynamoelectric – Rotary
Reexamination Certificate
2001-04-05
2003-12-02
Ramirez, Nestor (Department: 2834)
Electrical generator or motor structure
Dynamoelectric
Rotary
C310S049030, C310S046000, C310S052000, C310S053000, C310S184000
Reexamination Certificate
active
06657335
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates generally to a stepping motor and a driving apparatus and, more particularly, to a stepping motor provided with exciting coils and a rotor provided with N/S poles so as to rotate following an excitation state of the exciting coils and also to a driving apparatus to drive a driven member by means of rotation of the stepping motor.
2. Description of the Related Art
An indicating apparatus, wherein a pointer for indicating, for example, a speed of a vehicle or a rotation speed of an engine is a driven member, is conventionally known as a driving apparatus having a stepping motor. The above indicating apparatus, as shown in
FIG. 5
, has a stepping motor
1
having exciting coils
1
a
1
,
1
a
2
and a rotor
1
b
on which five sets of N/S poles are magnetized in turn and which rotates following a change of an excitation state of the exciting coils
1
a
1
,
1
a
2
, a pointer
2
being linked with the rotational drive of the rotor
1
b,
a gear
3
to transmit the rotational drive of the rotor
1
b
to the pointer
2
, and a drive controller
4
to rotate the rotor
1
b
normally or reversely by controlling the excitation state of the exciting coils
1
a
1
,
1
a
2
.
Hereinafter, a relation between an excitation state of the exciting coils
1
a
1
,
1
a
2
and rotation of the rotor
1
b
is described with reference to
FIGS. 6A-6H
. First, in an excitation state regulated at excitation step S
1
, that is, the b-side of the exciting coil
1
a
2
becomes a non-excited state and the exciting coil
1
a
2
becomes the S pole, the N pole of the rotor
1
b
is attracted toward the a-side of the exciting coil
1
a
1
, and the rotor
1
b
becomes stable.
Next, excitation step S
8
is reached. When the b-side of the exciting coil
1
a
2
becomes the N pole and the a-side of the exciting coil
1
a
1
becomes the S pole, the rotor
1
b
turns by 9 degrees in an arrow Y
1
direction from the position of excitation step S
1
and stops, whereby the pointer
2
shifts in an arrow Y
3
direction (FIG.
5
).
Following the above, when the b-side of the exciting coil
1
a
2
and the a-side of the exciting coil
1
a
1
are respectively controlled as follows:
N pole, non-excited state (excitation step S
7
)→
N pole, N pole (excitation step S
6
)→
non-excited state, N pole (excitation step S
5
)→
S pole, N pole (excitation step S
4
)→
S pole, non-excited state (excitation step S
3
)→
S pole, S pole (excitation step S
2
), the rotor
1
b
turns by 9 degrees each time following the change of the excitation state.
When the excitation state of excitation step S
8
is generated again from excitation step S
1
, the rotor
1
b
rotates again by 9 degrees in the arrow Y
1
direction and becomes stable. Like the above, the rotor
1
b
turns by 9 degrees every step in the arrow Y
1
direction by repeatedly controlling the excitation state of the exciting coils
1
a
1
,
1
a
2
according to the excitation pattern consisting of the excitation steps S
8
to S
1
.
In order to rotate the rotor
1
b
in an arrow Y
2
direction, the excitation state of the exciting coils
1
a
1
,
1
a
2
is controlled according to a pattern opposite the above excitation pattern, i.e., from S
1
toward S
8
, whereby the pointer
2
shifts in an arrow Y
4
direction (FIG.
5
).
Next, an operation of the above indicating apparatus used for a vehicle-speedometer, for example, is described hereinafter. An angle data D
1
is supplied to the drive controller
4
, which angle data D
1
shows a rotation angle of the rotor
1
b
corresponding to a travel which is a difference between a target position of the pointer
2
and a present position thereof. The target position of the pointer
2
is calculated on the basis of speed information from a speed sensor. By means of the drive controller
4
controlling an excitation state of the exciting coils
1
a
1
,
1
a
2
according to this angle data D
1
, the pointer
2
shifts by only the above travel and indicates the target position.
With respect to the above indicating apparatus, however, a power swing caused by an input of the angle data D
1
affected by vibration and noise of the vehicle body could be brought about, wherein an actual travel of the pointer
2
differs from the target travel of the pointer
2
. If the power swing is repeated, a difference arises between the speed indicated by the pointer
2
and the speed information from the speed sensor, whereby the indicating apparatus can not carry out an accurate indication.
In order to solve such a problem, as shown in
FIG. 5
, a stopper
5
is provided at a position at which the pointer
2
indicates zero (for example, 0 km/h) so as to stop the pointer
2
thereat by shifting the pointer
2
toward the stopper
5
every timing of ignition ON/OFF or battery connection. That is, a reset operation to reset the difference between the speed indicated by the pointer
2
and the speed information from the speed sensor is carried out. Hereinafter, a rotation in the arrow Y
1
direction is called a reverse rotation. On the contrary, a rotation in the arrow Y
2
direction is called a normal rotation.
With respect to the above prior art indicating apparatus, however, the rotor
1
b
has to be reversed so that the pointer
2
securely abuts the stopper
5
. That is, the rotor
1
b
has to be reversed so that the pointer
2
can return larger than a normal deflection. Therefore, because the above reset operation has to be carried out regardless of the presence or absence of the difference between the speed indicated by the pointer
2
and the speed information from the speed sensor, much time is required for the reset operation.
Because the excitation state of the exciting coils
1
a
1
,
1
a
2
is continuously controlled even though the pointer
2
has fully returned to the stopper
5
, the pointer
2
repeats abutting and leaving the stopper
5
, thereby making an unpleasant clattering noise.
In order to solve the above problem, the indicating apparatus which closes the reset operation simultaneously with the abutment of the pointer
2
against the stopper
5
is proposed. That is, because an induction voltage is generated in the exciting coil
1
a
1
or
1
a
2
being in a no-excited state while the pointer
2
is not in contact with the stopper
5
and therefore the rotor
1
b
is moving, and, on the other hand, because an induction voltage is not generated in the exciting coil being in a non-excited state while the pointer
2
is in contact with the stopper
5
and, therefore, the rotor
1
b
is stopping, the voltage generated in either, being in the non-excited state, of the exciting coils can be detected at a timing of the exciting coil being controlled into the non-excited state.
Whether or not the induction voltage has been generated is judged, and if yes, movement of the pointer
2
is stopped on a judgment that the pointer
2
has abutted the stopper
5
.
However, the rotor
1
b
is not likely to stop immediately after the pointer
2
abutted the stopper
5
but to further turn by some gap of gears
3
.
The rotor
1
b
is continuously controlled to reverse in the state that the pointer
2
is in contact with the stopper
5
, the rotor
1
b
sometimes normally rotates at a timing of the exciting coils
1
a
1
,
1
a
2
being changed to the proper excited states.
Specifically, if the pointer
2
is to abut the stopper
5
, for example, in a state of the exciting coils
1
a
1
,
1
a
2
being in the excitation state regulated at excitation step S
2
, and when the pointer
2
is abutting the stopper
5
and the rotor
1
b
is stopping at the position shown in excitation step S
2
, the rotor
1
b
could normally rotate near excitation step S
4
if the exciting coils
1
a
1
,
1
a
2
are continuously controlled according to an excitation pattern of S
1
→S
8
→S
7
→S
6
→S
5
→S
4
→S
3
→S
2
→S
1
. . . .
Induction voltage is generated by the normal rotation of the rotor
1
b
at step S
3
even though the point
Armstrong Westerman & Hattori, LLP
Cuevas Pedro J.
Ramirez Nestor
Yazaki -Corporation
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