Machine element or mechanism – Gearing – Interchangeably locked
Reexamination Certificate
1999-10-20
2001-09-18
Herrmann, Allan D. (Department: 3682)
Machine element or mechanism
Gearing
Interchangeably locked
C074S384000
Reexamination Certificate
active
06289758
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a gear module capable of securely coupling a transmission gear and a output gear.
2. Related Background Art
For such related arts, the arts disclosed in Japanese Patent application Laid Open No. 60-145551 and No. 8-138299 have been known. For example, as shown in
FIGS. 7A and 7B
, the conventional gear module
20
comprises the gear
21
rotated by a driving force of a driving motor; the lever
22
capable of rotating around a shaft of the gear
21
; and the gear
23
which is pivotally fitted to the top of the lever
22
to be engaged with the gear
21
. Moreover, the gear module
20
comprises a pair of gears
24
and
25
which are disposed on both sides of the lever
22
, respectively, to be selectively engaged with the gear
23
.
The rotation direction of the gear
23
is changed in accordance with which gear of the gears
24
and
25
the gear
23
engages with. Specifically, when the gear
23
engages with the gear
24
, the gear
23
is allowed to rotate counterclockwise (see FIG.
7
A). On the other hand, when the gear
23
engages with the gear
24
, the gear
23
is allowed to rotate clockwise (see FIG.
7
B). For this reason, in which direction the gear
23
may rotate, a force is applied in the direction where the gears are engaged strongly, and the gear
23
never fails to engage with the gears
24
and
25
.
However, the conventional gear module
20
has been forced to reverse the rotation direction of the driving motor every time when engaging of the gear
23
with the gears
24
and
25
is switched, resulting in complexity of the motor control circuit for controlling the rotation of the driving motor. Here, if the driving motor is allowed to rotate only in the designated one direction, the structure of the motor control circuit becomes simple. However, with such structure of the conventional gear module
20
, when the driving motor is rotated, for example, so as to rotate the gear
23
clockwise shown in
FIG. 7B
, a force acts in the direction on contacting of the gears
23
and
24
, and accordingly the gears
23
and
24
come off from each other. The gears
23
and
24
come to weakly engage with each other.
Moreover, since the conventional gear module
20
switches the gear by suddenly reversing the rotation of the gear, a large load is applied to each gear, resulting in a low durability (or reliability) of the module
20
. Here, when another actuator is provided additionally and the lever
22
is swung by the driving force of this actuator, the load applied on the gear can be reduced. However, according to this method, the lever
22
must be swung in opposition to a pressing force due to engaging of the gears. Therefore, the load applied to the actuator is excessive.
SUMMARY OF THE INVENTION
The object of the present invention is to provide a gear module which is capable of allowing the gears to be engaged with each other with a sufficient force even when a driving motor is rotated only in one direction.
Another object of the present invention is to provide a gear module which is capable of swinging a lever with a small force, thereby applying no excessive load on an actuator.
A gear module of the present invention comprises an output gear pivotally fitted to a base; and a transmission gear rotated by a driving force from a driving motor to transmit it to the output gear, the gear module further comprises a power actuating lever having a base end pivotally fitted to the base to be rotated around the base end; an actuated lever having a top end pivotally fitted to the transmission lever and a base end pivotally fitted to the base; and a connection bar connecting the top end of the power actuating lever and the top end of the actuated lever, the connection bar allowing the actuated gear to rotate in accordance with the rotation of the power actuating lever and allowing the transmission gear and the output gear to be engaged with each other, wherein the power actuating lever and the connection bar form approximately a straight line when the transmission lever is engaged with the output gear.
When such construction is adopted, the power actuating lever and the actuated lever moves in association with each other by connection bar. Therefore, upon rotation of the power actuating lever, the actuated lever rotates in accordance with the rotation of the power actuating lever. When the actuated lever rotates and the top end thereof moves toward the output gear, the transmission gear pivotally fitted to the top end of the actuated lever is engaged with the output gear. At this time, a force may act on the power actuating lever by the rotation load of the output gear in a direction where the transmission gear comes to separate from the output gear. However, since the power actuating lever and the connection bar form approximately a straight line when the transmission gear is engaged with the output gear, this force acts onto the straight line formed by the power actuating lever and the connection bar. Therefore, since this force does not act in the direction where the power actuating lever is rotated, the transmission gear never comes off from the output gear. As a result, the transmission gear and the output gear keep their engagement state.
Moreover, in the present invention, the power actuating lever comprises an elastic member which energizes the power actuating lever in a gear releasing direction to separate the transmission gear from the output gear; and an actuator which rotates the power actuating lever in a direction opposite to the gear releasing direction in opposition to an energizing force of the elastic member, wherein when application of a current to the actuator is stopped, the power actuating lever is separated from the output gear by the energizing force of the elastic member.
When such constitution is adopted, upon application of a current to the actuator, the power actuating lever rotates in a direction opposite to the gear releasing direction and the actuated lever in association with the power actuating lever also rotates. Then, the transmission gear pivotally fitted to the top end of the actuated lever is engaged with the output gear, whereby a driving force of the transmission gear is transmitted to the output gear. As a result, the output gear starts to rotate. Thereafter, when the application of the current to the actuator is stopped, the power actuating lever rotates in the gear releasing direction by the energizing force of the elastic member, whereby the transmission gear is separated from the output gear. As a result, the output gear stops to rotate. As described above, when the application of the current to the actuator is stopped by an occurrence of a unexpected power failure and the like, the transmission gear is automatically separated from the output gear, so that locking of the output gear is released. Therefore, an occurrence of the situation can be avoided, in which because of the lock of the output gear a driving mechanism driven by the output gear can not move keeping its driving state.
Moreover, in the above described present invention, a second output gear is further provided, which is pivotally fitted to the base and disposed in a direction opposite to the output gear relative to the transmission gear, the second output gear being engaged with the transmission gear separated from the output gear, and the transmission gear is selectively engaged either with the output gear or with the second output gear in accordance with the rotation of the actuated lever.
When such constitution is adopted, the transmission gear can be selectively engaged either with the output gear or with the second output gear in accordance with the rotation of the actuated lever, whereby the two output gears can be driven by a single driving motor. As a result, the number of parts can be reduced and a reduction in cost can be achieved.
A gear module according to the present invention comprises an input gear which rotates by a driving force of a driving motor; and a
Iiijiya Toshinori
Kasahara Takashi
Kugio Mitsuyasu
Takagi Masaaki
Herrmann Allan D.
Nidec Copal Corporation
Oppenheimer Wolff & Donnelly LLP
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