Drive unit for initialization

Details Drive unit for initialization Drive unit for initialization

2002-10-16

2004-05-25

Duda, Rina (Department: 2837)

Electricity: motive power systems

Positional servo systems

With particular motor control system responsive to the...

C318S696000, C324S163000, C324S164000, C073S001370, C073S001880

Reexamination Certificate

active

06741058

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a drive unit for initialization, especially to a drive unit for initialization to reset a condition of step-out of a stepping motor for driving a pointer mounted in an indicator of a vehicle.
2. Description of the Related Art
An indicator shown in
FIG. 1
exists usually as an indicator for a vehicle by a stepping motor. In
FIG. 1
, the indicator includes a stepping motor
1
, a pointer
2
interlocking rotation of the stepping motor
1
and a drive unit
8
for stepping motor (call a drive unit
8
simply hereafter) for rotating normally and reversely the stepping motor
1
. The stepping motor
1
, as mentioned above, includes two exciting coils
1
a
1
and
1
a
2
, a rotor
1
b
being magnetized each three poles alternately N pole and S pole and rotating to follow the change of excited conditions of the exciting coils
1
a
1
and
1
a
2
, and a gear
1
d
transmitting a driving force of the rotor
1
b
to the pointer
2
.
The stepping motor
1
, which is mounted on the back side against the gear id at the same side of the pointer
2
, includes a piece
1
e
as a driven member interlocking rotation of the rotor
1
b
; a not-shown receiving case for receiving the exciting coils
1
a
1
and
1
a
2
, the rotor
1
b
, the gear
1
d
and the piece
1
e
; and a stopper
1
f
being mounted at the receiving case and stopping mechanically rotation of the rotor
1
b
to abut on the piece
1
e.
Reverse rotation is defined by rotating the stepping motor
1
to move the piece
1
e
toward the stopper
1
f
. A direction of reverse rotation Y
1
is defined by a direction of rotation of the pointer
2
in reverse rotation. Oppositely, normal rotation is defined by rotating the stepping motor
1
to move the piece le apart from the stopper
1
f
and a direction of normal rotation Y
2
is defined by a direction of rotation of the pointer
2
in normal rotation. The stopper
1
f
is located to make the pointer
2
point a scale reading of 0 Km/h on a scale plate when the stopper if abuts on the piece
1
e.
When above indicator is used for a car speedometer, the drive unit
8
rotates the rotor
1
b
correspondingly to an amount of moving è-è′ of a difference of a target position è and a current position è′ of the pointer
2
to make the pointer
2
move the difference of è-è′ for pointing the target position è. The target position è is renewed by an angle datum èi whenever the angle datum èi calculated with a speed datum by an output of a car speed sensor is inputted. The angle datum èi is calculated as reference angle zero degree at speed datum of zero Km/h and increased in proportion of increasing speed datum.
The indicator may have step-out, which is an phenomenon of difference of a required moving amount (difference of è-è′) and an actual moving amount of the pointer
2
, caused by vibration of a car or inputting of an angle datum with superposed noise. If the step-out is repeated, a speed pointed by the pointer
2
is different from a speed datum measured by the speed sensor so that the indicator cannot indicate accurately.
Therefore, for solving such trouble, a later-described initializing operation is acted by the drive unit
8
. In the initializing operation, the drive unit
8
rotates reversely the stepping motor
1
to move the piece
1
e
toward the stopper
1
f
whenever an ignition switch is turned ON. Thereafter, the drive unit
8
stops electrically rotation of the stepping motor
1
to maintain exciting coils
1
a
1
and
1
a
2
in a predetermined initial excited condition when the piece
1
e
abuts on the stopper
1
f
and the pointer
2
stops mechanically at an abutting position as a scale reading of 0 Km/h on a scale plate. By acting the initializing operation as mentioned above, when the current position è′ is sensed as 0 degree, the pointer
2
points at a scale reading of 0 Km/h as the abutting position. Thus, difference of the speed pointed by the pointer
2
and the speed datum measured by the speed sensor can be reset.
Objects to be Solved
The indicator as mentioned above is initialized at timing when the ignition switch is turned ON. Therefore, the usual indicator cannot indicate a measured value immediately after being activated correspondingly to turning the ignition switch ON. Especially, when the indicator is used for a tachometer, the indicator may not indicate a rotation speed of an engine for an initializing operation although the engine has started. It has been required that motion of the pointer in the initializing operation is hidden from a driver.
To solve such problems, it is considered that the initializing operation is acted at timing when the ignition switch is turned OFF. If time from the initializing operation to starting the indicator is required much, a car is vibrated during the time so that possibility of step-out is increased. Therefore, step-out may be occurred when starting the indicator and then the indicator cannot indicate accurately.
To overcome the above drawback of prior art, one object of this invention is to provide a drive unit for initialization, in which a pointer in an indicator for a vehicle can point immediately after an ignition switch is turned ON by starting the initializing operation correspondingly to an open/close operation of a door of a vehicle, and frequency of seeing motion of a pointer in the initializing operation by a car driver is reduced.
SUMMARY OF THE INVENTION
How to Attain the Object
In order to attain the objects, a drive unit for initialization according to this invention, which includes, as shown in
FIG. 1
of a basic structure block diagram; drive means
8
a
-
1
for initializing a stepping motor
1
to rotate for actuating a pointer mounted in an indicator of a vehicle so as to move a driven member, interlockingly with rotation of the stepping motor, toward a stopper for stopping the rotation of the stepping motor mechanically by abutting on the driven member; and drive-stop means
8
a
-
2
for stopping the rotation of the stepping motor electrically after the driven member being abutted on the stopper, comprises sensing means
8
a
-
3
for sensing an open/close operation of a door of the vehicle, and drive-start means
8
a
-
4
for starting rotation of the stepping motor by the drive means for initialization correspondingly to an output of the sensing means when an ignition switch is in a state of OFF condition.
According to the above structure, the sensing means senses an open/close operation of a door of a vehicle. The drive-start means starts rotation of the stepping motor by the drive means for initialization correspondingly to an output of the sensing means when the ignition switch is in a state of OFF condition. The drive means for initialization rotates the stepping motor so as to move a driven member, interlockingly with rotation of the stepping motor for actuating a pointer in an indicator of a vehicle, toward a stopper for stopping the rotation of the stepping motor mechanically by abutting on the driven member. The drive-stop means stops the rotation of the stepping motor electrically after the driven member being abutted on the stopper.
A car driver turns the ignition switch ON to start the indicator for a vehicle usually after open and close a door to go into a car. Therefore, the initializing operation can be completed before the ignition switch is turned ON, by starting the operation by the drive means for initialization when the ignition switch is in a state of OFF condition and an open/close operation of a door is sensed.
Advantageously, the drive unit for initialization according to this invention, shown in
FIG. 1
of a basic structure block diagram, is characterized by the fact that the sensing means senses an open/close operation of the door of the vehicle when a door-lock switch SW
2
is turned ON or OFF to lock or unlock the door in the drive unit for initialization mentioned above.
According to the above structure, when the door-lock switch is turned ON or OFF to lock

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