Machine element or mechanism – Mechanical movements – Reciprocating or oscillating to or from alternating rotary
Reexamination Certificate
1999-11-24
2001-10-30
Fenstermacher, David (Department: 3682)
Machine element or mechanism
Mechanical movements
Reciprocating or oscillating to or from alternating rotary
C074S089260, C185S04000C, C185S04000C, C185S04000C, C292S201000
Reexamination Certificate
active
06308587
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to an actuator for use in a vehicle-door locking mechanism, which includes an automatic bidirectional-returning mechanism using a single return coil spring as a home returning spring for allowing a manual operation.
As such an actuator, there is a conventional one shown in
FIGS. 5 and 6A
to
6
C.
FIG. 5
is a plan view of the constitution of a major part of the prior art actuator. In this figure, reference numeral
51
denotes a driving motor,
52
shows a small gear such as a helical pinion attached to a shaft of the driving motor, and
53
indicates a large gear such as a helical worm gear engaged with the small gear
52
. Furthermore, reference numeral
54
shows a lead screw serving as a main shaft fixed to the large gear
53
so as to penetrate the center thereof and having a screw section
54
a
on the circumference thereof,
55
indicates a nut member fitted on the lead screw
54
and moved along the axis of the screw
54
in accordance with the rotation of the screw
54
, and
56
denotes a lever turned on its axis within the range of a given angle in accordance with the movement of the nut member
55
. Reference numeral
57
denotes an output shaft provided coaxially with the axis of the lever
56
and numeral
58
indicate s an output arm for transmitting the rotation force of the output shaft
57
to a door locking mechanism (not shown).
An automatic bidirectional-returning mechanism
60
for returning the lead screw
54
to its home position (initial position) is mounted on an elongated end portion of the lead screw
54
which penetrates the large gear
53
toward the right side of FIG.
5
.
FIG. 6A
is a perspective view of the constitution of the automatic bidirectional-returning mechanism
60
. Referring to
FIG. 6A
, the mechanism
60
includes a bobbin
61
fixed coaxially to the elongated end portion of the lead screw
54
. The bobbin
61
includes a cylindrical section (not shown) having a predetermined length and located on its axis, a pair of flanges
61
a
and
61
b
provided on both ends of the cylindrical section so as to be opposed to each other, and a strip-like operation member
61
c
so as to build a bridge between the flanges
61
and
61
b.
A single home-returning coil spring
62
is wound around the bobbin
61
. Both ends of the coil spring
62
are each bent like a letter “L” in the radial direction thereof, and these bent portions serve as engaging end portions
62
a
and
62
b.
One engaging end portion
62
a
passes near one side of the operation member
61
c
of the bobbin
61
and its tip is brought into contact with one side of a stopper
64
at a given pressure. The other engagement end portion
62
b
passes near the other side of the operation member
61
c
of the bobbin
61
and its tip is brought into contact with the other side of the stopper
64
at a given pressure.
The stopper
64
is formed on a mounting base
63
of an actuator holding case integrally with the base
63
as one unit. The stopper
64
is formed of a rectangular projection in parallel with the axis of the coil spring
62
.
The prior art actuator so constituted operates as follows. If the driving motor
51
rotates forward to lock the door of a vehicle, the small gear
52
rotates in the direction of arrow A in FIG.
5
and accordingly the large gear
53
rotates in the direction of arrow B. The nut member
55
thus moves relatively in the direction of arrow C. A projection
55
a
of the nut member
55
is then pressed on the left inner side of a fitting window
56
a
of the lever
56
in FIG.
5
. The lever
56
therefore turns in the direction of arrow D
1
. As the lever
56
turns, the output arm
58
turns around its output axis
57
in the direction of arrow E
1
. If the output arm
58
turns by a distance corresponding to a stroke S
1
, the door locking mechanism (not shown) is locked.
When the large gear
53
and lead screw
54
start rotating in the direction of arrow B, the bobbin
61
of the mechanism
60
, fixed to the lead screw
54
, also starts rotating in the same direction. The operation member
61
c
thus causes the engaging end portion
62
a
of the coil spring
62
to be biased in the direction of arrow F
1
in FIG.
6
B. Since the other engagement end portion
62
b
of the coil spring
62
is engaged with the other side of the stopper
64
, the coil spring
62
is compressed gradually according to the rotation of the operation member
61
c
. As indicated by the broken line in
FIG. 6C
, when the engaging end portion
62
a
biased by the operation member
61
c
reaches and contacts the other side of the stopper
64
, the portion
62
a
cannot rotate any more.
In this state, the power of the driving motor
51
is cut off by means of, e.g., a limit switch and the motor
51
stops rotating accordingly. If the driving motor
51
stops, the decompression force of the compressed coil spring
62
is transmitted to the lead screw
54
through the bobbin
61
and also to the motor
51
through the small and large gears
52
and
53
. The motor
51
and lead screw
54
thus rotate backward. The nut member
55
moves in a direction opposite to that of arrow C and returns to its initial position. When the engagement end portion
62
a
of the coil spring
62
returns to one side of the stopper
64
, the above decompression force is lost. The nut member
55
is therefore returned to the initial position and stabilized.
The returning operation of the nut member
55
is performed independently within the range of the fitting window
56
a
of the lever
56
such that it does not contact the lever
56
. The lever
56
thus remains stationary in which position a door locking operation is performed or in which position the lever
56
is rotated only through an angle &thgr;1.
When the driving motor
51
rotates backward to unlock the vehicle door, the small gear
52
, large gear
53
and lead screw
54
rotate in a direction opposite to the above direction, and the nut member
55
moves in a direction opposite to that of arrow C. The lever
56
thus turns in the direction of arrow D
2
, the output shaft
57
rotates in the same direction, and the output arm
58
turns in the direction of arrow E
2
. If the output arm
58
turns by a distance corresponding to a stroke S
2
, the door locking mechanism is unlocked.
The automatic bidirectional-returning mechanism
60
performs an operation opposite to the foregoing operation. More specifically, the engagement end portion
62
b
of the coil spring
62
is biased in the direction of arrow F
2
in
FIG. 6B
such that the portion
62
b
is separated from the other side of the stopper
64
by means of the operation member
61
c
of the bobbin
61
. When the engagement end portion
62
b
reaches and contacts one side of the stopper
64
, the bias operation stops. In this time, a limit switch (not shown) operates to cut off the power of the driving motor
51
and stop its rotation.
In the prior art door locking actuator having the above constitution, the lead screw
54
can rotate only one rotation or less in either the forward or backward direction. Usually, the lead screw
54
can turn only ±0.88 turn. The operation end of the output arm
58
thus needs shifting by a required stroke S
1
=S
2
(about 15 mm at the tip of the arm) in order to sufficiently operate the door locking mechanism and accordingly the lead angle &bgr; of the lead screw
54
has to be considerably large. If the lead angle &bgr; is increased, naturally, the driving force of the door locking mechanism is likely to lower to cause a malfunction.
The lead angle &bgr; is obtained by the following equation: tan&bgr;=L/2&pgr; r, where L represents a lead (the distance by which the screw advances). Incidentally, the lead L of the conventional lead screw is 6.16 mm.
To achieve the above stroke S
1
=S
2
, the lead L of the lead screw
54
should be set to 8.1 mm or more. However, this causes the problem that the torque of the lead screw
54
is decreased extremely and a necessar
Shinkawa Masaki
Tanaka Yutaro
Fenstermacher David
Harada Industry Co. Ltd.
Pennie & Edmonds LLP
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