U.S. patent application number 12/230066 was filed with the patent office on 2009-03-05 for seat belt retractor.
This patent application is currently assigned to TAKATA CORPORATION. Invention is credited to Koji Hiramatsu, Masao Hisaki, Yasushi Kanamori.
Application Number | 20090057470 12/230066 |
Document ID | / |
Family ID | 40202192 |
Filed Date | 2009-03-05 |
United States Patent
Application |
20090057470 |
Kind Code |
A1 |
Hiramatsu; Koji ; et
al. |
March 5, 2009 |
Seat belt retractor
Abstract
A seat belt retractor including a spool for winding up the seat
belt, and a locking mechanism that prevents rotation of the spool.
A belt withdrawal sensor actuates when the seat belt is withdrawn
at a speed higher than a normal speed. The locking mechanism is
actuated based on the actuation of the belt withdrawal sensor. A
lock gear rotates with the spool when the locking mechanism is not
in operation and rotates relative to the spool when the lock
actuation mechanism is in operation. The lock gear actuates the
locking mechanism by relative rotation between the lock gear and
the spool. The belt withdrawal sensor is disposed on the lock gear
allowing the belt withdrawal sensor to oscillate between an
inoperative position and an operative position. An oscillation
preventive member prevents the oscillation of the belt withdrawal
sensor.
Inventors: |
Hiramatsu; Koji; (Tokyo,
JP) ; Kanamori; Yasushi; (Tokyo, JP) ; Hisaki;
Masao; (Tokyo, JP) |
Correspondence
Address: |
FOLEY AND LARDNER LLP;SUITE 500
3000 K STREET NW
WASHINGTON
DC
20007
US
|
Assignee: |
TAKATA CORPORATION
|
Family ID: |
40202192 |
Appl. No.: |
12/230066 |
Filed: |
August 22, 2008 |
Current U.S.
Class: |
242/396.1 |
Current CPC
Class: |
B60R 22/405 20130101;
B60R 22/41 20130101 |
Class at
Publication: |
242/396.1 |
International
Class: |
B65H 23/04 20060101
B65H023/04 |
Foreign Application Data
Date |
Code |
Application Number |
Sep 4, 2007 |
JP |
2007-229006 |
Claims
1. A seat belt retractor for winding up a seat belt comprising: a
spool for winding up the seat belt; a locking mechanism that allows
the rotation of the spool when the locking mechanism is not in
operation and prevents rotation of the spool in a belt withdrawing
direction when the locking mechanism is in operation; a belt
withdrawal sensor that is actuated when the seat belt is withdrawn
at a speed higher than a normal speed at a start of the withdrawal
of the seat belt, and; a lock actuation mechanism that actuates the
locking mechanism based on the actuation of the belt withdrawal
sensor, wherein the lock actuation mechanism comprises at least a
lock gear that rotates together with the spool when the lock
actuation mechanism is not in operation and rotates relative to the
spool when the lock actuation mechanism is in operation, the lock
gear actuating the locking mechanism by the relative rotation
between the lock gear and the spool when the lock actuation
mechanism is in operation, and wherein the belt withdrawal sensor
is disposed on the lock gear allowing the belt withdrawal sensor to
oscillate between an inoperative position where the belt withdrawal
sensor allows the rotation of the lock gear both in the belt
winding direction and the belt withdrawing direction and an
operative position where the belt withdrawal sensor prevents the
rotation of the lock gear at least in the belt withdrawing
direction, the seatbelt retractor further comprising: an
oscillation preventive member for preventing the oscillation of the
belt withdrawal sensor and an oscillation preventive member control
mechanism for controlling the movement of the oscillation
preventive member, wherein the oscillation preventive member is
movable in a radial direction through a rotational center of the
spool between an oscillation preventing position where the
oscillation preventive member holds the belt withdrawal sensor at
the inoperative position to prevent the belt withdrawal sensor from
oscillating toward the operative position at least when the seat
belt is fully or nearly fully wound, and an oscillation allowing
position where the oscillation preventive member allows the
oscillation of the belt withdrawal sensor when a certain amount of
the seat belt is withdrawn from the fully wound state, and wherein
the oscillation preventive member control mechanism comprises a
movement control member that rotates at a speed lower than the
speed of the spool to control the movement of the oscillation
preventive member when the spool rotates.
2. A seat belt retractor as claimed in claim 1, further comprising:
an emergency locking mechanism that detects a vehicle deceleration
larger than a normal deceleration and actuates to prevent the spool
from rotating in the belt withdrawing direction; an automatic
locking mechanism that is actuated when the seat belt is fully
withdrawn and prevents the withdrawal of the seat belt during
winding after the seat belt is fully withdrawn until a certain
amount of the seat belt is wound; and a lock switching mechanism
for switching between an emergency locking function mode in which
an emergency locking function is executed by the emergency locking
mechanism and an automatic locking function mode in which an
automatic locking function is executed by the automatic locking
mechanism, the lock switching mechanism comprising: a switching
lever that is selectively set at either of an emergency locking
position where the emergency locking function mode is set or an
automatic locking position where the automatic locking function
mode is set, and an eccentric gear that rotates when the spool
rotates, the eccentric gear rotating at a speed lower than the
rotational speed of the spool and comprising a switching lever
control cam member for switching the setting position of the
switching lever, wherein the movement control member comprises the
eccentric gear and the oscillation preventive member is a member of
which movement is controlled by the rotation of the eccentric gear
to prevent the actuation of the belt withdrawal sensor when the
seat belt is fully or nearly fully wound.
3. A seat belt retractor as claimed in claim 2, wherein the belt
withdrawal sensor comprises a ring member and the oscillation
preventive member comprises a plurality of stoppers that press an
inner periphery of the ring member to prevent actuation of the belt
withdrawal sensor when the seat belt is fully or nearly fully
wound.
4. A seat belt retractor as claimed in claim 3, wherein the
stoppers comprise a stopper biasing member for biasing the stopper
in a direction pressing against the ring member.
5. A seat belt apparatus comprising: a seat belt for restraining an
occupant; a seat belt retractor for winding up the seat belt while
allowing withdrawal of the seat belt, the seat belt retractor being
actuated in the event of an emergency to prevent the withdrawal of
the seat belt; wherein the retractor comprises a spool for winding
up the seat belt; a locking mechanism that allows the rotation of
the spool when the locking mechanism is not in operation and
prevents rotation of the spool in a belt withdrawing direction when
the locking mechanism is in operation; a belt withdrawal sensor
that is actuated when the seat belt is withdrawn at a speed higher
than a normal speed at a start of the withdrawal of the seat belt,
and; a lock actuation mechanism that actuates the locking mechanism
based on the actuation of the belt withdrawal sensor, wherein the
lock actuation mechanism comprises at least a lock gear that
rotates together with the spool when the lock actuation mechanism
is not in operation and rotates relative to the spool when the lock
actuation mechanism is in operation, the lock gear actuating the
locking mechanism by the relative rotation between the lock gear
and the spool when the lock actuation mechanism is in operation,
and wherein the belt withdrawal sensor is disposed on the lock gear
allowing the belt withdrawal sensor to oscillate between an
inoperative position where the belt withdrawal sensor allows the
rotation of the lock gear both in the belt winding direction and
the belt withdrawing direction and an operative position where the
belt withdrawal sensor prevents the rotation of the lock gear at
least in the belt withdrawing direction, an oscillation preventive
member for preventing the oscillation of the belt withdrawal sensor
and an oscillation preventive member control mechanism for
controlling the movement of the oscillation preventive member,
wherein the oscillation preventive member is movable in a radial
direction through a rotational center of the spool between an
oscillation preventing position where the oscillation preventive
member holds the belt withdrawal sensor at the inoperative position
to prevent the belt withdrawal sensor from oscillating toward the
operative position at least when the seat belt is fully or nearly
fully wound, and an oscillation allowing position where the
oscillation preventive member allows the oscillation of the belt
withdrawal sensor when a certain amount of the seat belt is
withdrawn from the fully wound state, and wherein the oscillation
preventive member control mechanism comprises a movement control
member that rotates at a speed lower than the speed of the spool to
control the movement of the oscillation preventive member when the
spool rotates. a tongue slidably supported by the seat belt, and a
buckle fixed to a vehicle floor or a vehicle seat and to which the
tongue is detachably latched.
Description
BACKGROUND
[0001] The present application relates generally to the field of a
seat belt apparatus for restraining an occupant with a seat belt
withdrawn from a seat belt retractor. More particularly, the
present application relates to a seat belt retractor including at
least a webbing sensor and that can prevent occurrence of an end
lock when the seat belt is fully wound. Furthermore, the present
application relates to a seat belt apparatus employing the
aforementioned seat belt retractor.
[0002] Conventionally, a seat belt apparatus installed in a vehicle
restrains an occupant in an emergency such as a crash, thereby
preventing the occupants from being ejected out of their seats.
[0003] Such seat belt units generally include a seat belt
retractor. Most conventional seat belt retractors are provided with
a webbing sensor that oscillates by rapid withdrawal of the seat
belt. The oscillation of the webbing sensor acts to prevent the
seat belt from being withdrawn. The webbing sensor may oscillate to
cause an end lock when the withdrawn seat belt is fully wound. The
end lock can make normal withdrawal of the seat belt difficult.
SUMMARY
[0004] One embodiment of the disclosure relates to a seat belt
retractor including a seat belt for restraining an occupant and a
spool for winding up the seat belt. The seat belt retractor also
includes a locking mechanism that allows the rotation of the spool
when the locking mechanism is not in operation and prevents
rotation of the spool in a belt withdrawing direction when the
locking mechanism is in operation. The seat belt retractor also
includes a belt withdrawal sensor that is actuated when the seat
belt is withdrawn at a speed higher than a normal speed at a start
of the withdrawal of the seat belt. The seat belt retractor also
includes a lock actuation mechanism that actuates the locking
mechanism based on the actuation of the belt withdrawal sensor. The
lock actuation mechanism includes a lock gear that rotates together
with the spool when the lock actuation mechanism is not in
operation and rotates relative to the spool when the lock actuation
mechanism is in operation. The lock gear actuates the locking
mechanism by the relative rotation between the lock gear and the
spool when the lock actuation mechanism is in operation. The belt
withdrawal sensor is disposed on the lock gear allowing the belt
withdrawal sensor to oscillate between an inoperative position
where the belt withdrawal sensor allows the rotation of the lock
gear both in the belt winding direction and the belt withdrawing
direction and an operative position where the belt withdrawal
sensor prevents the rotation of the lock gear at least in the belt
withdrawing direction. The seatbelt retractor also includes an
oscillation preventive member for preventing the oscillation of the
belt withdrawal sensor and an oscillation preventive member control
mechanism for controlling the movement of the oscillation
preventive member. The oscillation preventive member is movable in
a radial direction through a rotational center of the spool between
an oscillation preventing position where the oscillation preventive
member holds the belt withdrawal sensor at the inoperative position
to prevent the belt withdrawal sensor from oscillating toward the
operative position at least when the seat belt is fully or nearly
fully wound and an oscillation allowing position where the
oscillation preventive member allows the oscillation of the belt
withdrawal sensor when a certain amount of the seat belt is
withdrawn from the fully wound state. The oscillation preventive
member control mechanism includes a movement control member that
rotates at a speed lower than the speed of the spool to control the
movement of the oscillation preventive member when the spool
rotates.
BRIEF DESCRIPTION OF THE DRAWINGS
[0005] These and other features, aspects, and advantages of the
present invention will become apparent from the following
description, appended claims, and the accompanying exemplary
embodiments shown in the drawings, which are briefly described
below.
[0006] FIG. 1 is a schematic diagram showing a seat belt retractor,
according to an exemplary embodiment.
[0007] FIG. 2 is a schematic diagram showing a seat belt retractor,
according to an exemplary embodiment.
[0008] FIG. 3 is a perspective view of an ELR-ALR switching
mechanism, an end lock preventive mechanism for a vehicle sensor,
and an end lock preventive mechanism for a webbing sensor of the
seat belt retractor, according to an exemplary embodiment.
[0009] FIGS. 4(a), 4(b) are illustrations showing the behavior of
the webbing sensor of the seat belt retractor, according to an
exemplary embodiment. FIG. 4(a) is an illustration of the webbing
sensor in its inoperative state. FIG. 4(b) is an illustration of
the webbing sensor in its operative state.
[0010] FIG. 5 is an illustration showing the ELR-ALR switching
mechanism, the end lock preventive mechanism for the vehicle
sensor, and the end lock preventive mechanism for the webbing
sensor, according to exemplary embodiment.
[0011] FIGS. 6(a) and 6(b) are illustrations of the end lock
preventive mechanism for the webbing sensor used in an exemplary
embodiment. FIG. 6(a) is a schematic diagram of stoppers. FIG. 6(b)
is a schematic diagram of cam grooves for controlling the
stoppers.
[0012] FIGS. 7(a)-7(d) show a switching action from the ELR
function mode to the ALR function mode used in the seat belt
retractor of an exemplary embodiment.
[0013] FIGS. 8(a) and 8(b) show another part of the switching
action from the ELR function mode to the ALR function mode used in
the seat belt retractor of an exemplary embodiment.
[0014] FIGS. 9(a)-9(d) show a part of the action of the end lock
preventive mechanism for the vehicle sensor, according to an
exemplary embodiment.
[0015] FIGS. 10(a) and 10(b) show a further part of the action of
the end lock preventive mechanism for the vehicle sensor, according
to an exemplary embodiment.
[0016] FIGS. 11(a) and 11(b) show a part of the action of the end
lock preventive mechanism for the fly wheel of an exemplary
embodiment. FIGS. 11(c) and 11(d) show a part of the behavior of a
pair of stoppers and cam grooves for controlling the action of the
end lock preventive mechanism for the fly wheel of the
embodiment.
[0017] FIGS. 12(a) and 12(b) show another part of the action of the
end lock preventive mechanism for the fly wheel, according to an
exemplary embodiment. FIGS. 12(c) and 12(d) show another part of
the behavior of the pair of stoppers and the cam grooves for
controlling the action of the end lock preventive mechanism for the
fly wheel, according to an exemplary embodiment.
[0018] FIG. 13(a) shows a remaining part of the action of the end
lock preventive mechanism for the fly wheel, according to an
exemplary embodiment. FIG. 13(b) shows a remaining part of the
behavior of the pair of stoppers and the cam grooves for
controlling the action of the end lock preventive mechanism for the
fly wheel, according to an exemplary embodiment.
[0019] FIG. 14 shows stoppers of an alternative exemplary
embodiment.
DETAILED DESCRIPTION
[0020] According to one exemplary embodiment, a seat belt retractor
can prevent an end lock due to a webbing sensor as disclosed in
JP-A-09-058410m which is herein incorporated by reference in its
entirety. A seat belt unit may include a cam plate that rotates
according to the rotation of the spool for winding up a seat belt.
A helical long groove is formed upon the cam plate. The seat belt
retractor also includes an oscillation preventive member for
preventing oscillation of the webbing sensor. The oscillation
preventive member is arranged such that the oscillation preventive
member is pivotally movable between a position for allowing
oscillation of the webbing sensor and a position for preventing
oscillation of the webbing sensor. The pivotal movement of the
oscillation preventive member is controlled by a cam follower of
the oscillation preventive member that is guided along the cam
groove of the cam plate.
[0021] The pivotal movement of the oscillation preventive member
may be controlled such that the oscillation preventive member is
pivotally moved toward an oscillation allowing position. The
oscillation preventive member is moved due to the rotation of the
cam plate in the belt withdrawing direction. Furthermore, the
oscillation preventive member is pivotally moved toward the
oscillation preventing position when the cam plate is rotated in
the belt winding direction. When the belt is fully wound, the
oscillation preventive member is set to an oscillation preventing
position. In the oscillation preventing position, the belt
withdrawal sensor is not allowed to oscillate thereby preventing an
end lock. When the fully wound seat belt is withdrawn by a
predetermined amount, the oscillation preventive member is set at
the oscillation allowing position. The belt withdrawal sensor is
allowed to oscillate, preventing withdrawal of the seat belt when
the seat belt is rapidly withdrawn.
[0022] The oscillation preventive member may rotate with the spool
for withdrawing and winding the seat belt. The amount the
oscillation preventive member rotates between the oscillation
allowing position and the oscillation preventing position is small
relative to the spool. The cam groove may be relatively long and
may be formed with an increased number of helical circles. To
increase the number of helical circles of the cam groove, the outer
diameter of the cam plate can be increased. Therefore, the size of
the seat belt retractor may be increased.
[0023] Diversification of vehicles generally results in diverse
layouts of seat belt units. The range for forming the cam groove of
the cam plate and the moving range of the oscillation preventive
member may vary depending on the layout of the seat belt unit.
Therefore, a large number of parts may be used to accommodate
various layouts of the seat belt unit. However, in the case of a
seat belt retractor having a large cam plate, it may be difficult
to accommodate multiple layouts.
[0024] According to other exemplary embodiments, the seat belt
retractor may be compact and effectively prevent an end lock due to
a belt withdrawal sensor. The seat belt retractor may includes a
mechanism for preventing an end lock. A seat belt unit may include
the seat belt retractor.
[0025] According to an exemplary embodiment, a seat belt retractor
includes a seat belt for restraining an occupant, a spool for
winding up the seat belt, and a locking mechanism. The locking
mechanism may allow rotation of the spool when the locking
mechanism is not in operation, and may prevent rotation of the
spool in the belt withdrawal direction when the locking mechanism
is in operation. The seat belt retractor may further include a belt
withdrawal sensor and a lock actuation mechanism. The belt
withdrawal sensor may be actuated when the seat belt is withdrawn
at a speed greater than a predetermined speed at the start of the
withdrawal of the seat belt. The lock actuation mechanism may
actuate a locking mechanism according to the actuation of the belt
withdrawal sensor. The lock actuation mechanism includes at least a
lock gear. The lock gear rotates with the spool when the lock
actuation mechanism is not in operation, and rotates relative to
the spool when the lock actuation mechanism is in operation.
Furthermore, the lock gear may actuate the locking mechanism by the
relative rotation between the lock gear and the spool when the lock
actuation mechanism is in operation. A belt withdrawal sensor may
be disposed on the lock gear such that the belt withdrawal sensor
may oscillate between an inoperative position and an operative
position. In the inoperative position, rotation of the lock gear in
either direction is allowed. In the operative position, the belt
withdrawal sensor may prevent the rotation of the lock gear at
least in the belt withdrawing direction. The belt withdrawal sensor
may include an oscillation preventive member and an oscillation
preventive member control mechanism. The oscillation preventive
member may be moved in a radial direction passing through the
rotational center of the spool between an oscillation preventing
position and an oscillation allowing position. In the oscillation
preventing position the oscillation preventive member may hold the
belt withdrawal sensor at the inoperative position. In the
oscillation allowing position, the oscillation preventive member
may allow oscillation of the belt withdrawal sensor. The
oscillation preventive member control mechanism may also include a
movement control member. The movement control member may rotate at
a speed lower than that of the spool, thereby controlling movement
of the oscillation preventive member when the spool rotates.
[0026] A seat belt retractor according to an exemplary embodiment
includes an emergency locking mechanism and an automatic locking
mechanism. The emergency locking mechanism may actuate when a
deceleration larger than a predetermined deceleration is detected,
thereby preventing the spool from rotating in the belt withdrawal
direction. The automatic locking mechanism may actuate when the
seat belt is fully withdrawn and may prevent withdrawal of a fully
withdrawn seat belt until a predetermined amount of the seat belt
is wound. Additionally, the seat belt retractor may include a lock
switching mechanism for switching between an emergency locking
function mode and an automatic locking function mode. The lock
switching mechanism may include a switching lever. The switching
lever may be set at either an emergency locking position where the
emergency locking function mode may be set or an automatic locking
position where the automatic locking function mode may be set. The
lock switching mechanism may also include an eccentric gear that
rotates at a speed lower than that of the spool when the spool
rotates. The eccentric gear includes at least a switching lever
control cam member for switching the setting position of the
switching lever. The movement control member may include the
eccentric gear. The oscillation preventive members movement may be
controlled by the rotation of the eccentric gear, preventing the
actuation of the belt withdrawal sensor when the seat belt is fully
or nearly fully wound.
[0027] According to an exemplary embodiment, the belt withdrawal
sensor of a seat belt retractor may include a ring member. The
oscillation preventive member may include a plurality of stoppers
that press the inner periphery of the ring member. As a result,
actuation of the webbing sensor may be prevented when the seat belt
is fully or nearly fully wound.
[0028] Furthermore, a seat belt retractor according to an
embodiment may include a stopper biasing means for biasing the
stopper in such a direction that the stoppers press the ring
member.
[0029] According to an exemplary embodiment, a seat belt unit may
include at least a seat belt for restraining an occupant, a tongue
slidably supported by the seat belt, and a buckle that may be fixed
to a vehicle floor or a vehicle seat and to which the tongue can be
detachably latched. The seat belt unit may also include a seat belt
retractor for performing at least one of winding up or withdrawal
of a seat belt. The seat belt retractor may be actuated in the
event of an emergency to prevent the withdrawal of the seat belt.
Furthermore, the seat belt retractor may be a seat belt retractor
as claimed in any one of claims 1 through 4.
[0030] In a seat belt retractor having the aforementioned
structure, when the seat belt is fully or nearly fully wound, the
oscillation preventive member may be moved by the movement control
member. The oscillation preventive member may move in a radial
direction that passes through the rotational center of the spool
and may thus be set at the oscillation preventing position.
Therefore, the oscillation of the belt withdrawal sensor may be
prevented so that the belt withdrawal sensor is held at its
inoperative position. Therefore, an end lock due to the belt
withdrawal sensor can be prevented by a simple structure.
[0031] More particularly, since the movement control member is
adapted to rotate at a reduced speed, the amount of rotation of the
movement control member until the spool fully winds up the seat
belt can be reduced. As a result, the movement control member may
be of simple and compact construction.
[0032] The movement control member includes the eccentric gear of
the lock switching mechanism. Furthermore, the eccentric gear is a
flat member. Therefore, the compact design of the movement control
member may be more easily achieved. In addition, since the
eccentric gear of the lock switching mechanism may be used as the
movement control member, an exclusive control member for
controlling the oscillation preventive member is not required.
Accordingly, the parts count of the seat belt retractor of the
automatic locking type can be reduced, even with the function of
preventing an end lock due to the belt withdrawal sensor.
[0033] Further, since the belt withdrawal sensor is provided with
the ring member and the oscillation preventive member is composed
of stoppers, a conventional belt withdrawal sensor can be employed
without significant design change. Therefore, a further simple
structure is achieved because all that is required is to simply
press the ring member by the stoppers. In addition, since the
oscillation preventive member includes the stoppers that are of
simple structure, the seat belt retractor can be flexibly and
inexpensively adapted to various layouts of seat belt units.
Additionally, the seat belt retractor may require fewer parts by
suitably setting the movement distance of the stoppers relative to
the eccentric gear.
[0034] Furthermore, the stoppers may be biased in a direction
pressing the ring member by using a stopper biasing method.
Therefore, the ring member of the belt withdrawal sensor can be
locked with larger force.
[0035] According to an exemplary embodiment, end locks in the seat
belt retractor can be effectively prevented, thereby improving the
operability of the seat belt and enabling smooth and stable
operation by the occupant.
[0036] Hereafter, the preferred embodiments for carrying out the
present disclosure will be described with reference to the attached
drawings.
[0037] FIG. 1 is a schematic diagram of a seat belt apparatus
including a seat belt retractor according to an exemplary
embodiment.
[0038] As shown in FIG. 1, the seat belt unit 1 may include,
similar to a known seat belt unit, a seat belt retractor 3 and a
seat belt 4. The seat belt retractor 3 may be fixed to a vehicle
body near a vehicle seat 2, and the seat belt 4 may be withdrawn
from the seat belt retractor 3. The seat belt 4 includes a belt
anchor 4a fixed to a vehicle floor or the vehicle seat 2. The seat
belt unit 1 may also include a deflection fitting 5 for guiding a
seat belt 4 toward an occupant's shoulder, and a tongue 6 slidably
supported by the seat belt 4. Additionally, a buckle 7 may be fixed
to the vehicle floor or the vehicle seat 2 such that the tongue 6
can be inserted and detachably latched.
[0039] The seat belt retractor 3 of the embodiment includes a
U-like frame 8 (that may be similar to conventional seat belt
retractors) that includes a back wall 8a and left and right side
walls 8b, 8c. The left and right side walls 8b, 8c project from
edges of the back wall 8a in a direction perpendicular to the
extending direction of the back wall 8a as shown in FIG. 2.
[0040] A spool 9 that the seat belt 4 is wound on may be inserted
through circular holes formed in side walls 8b, 8c of the frame 8
such that the spool 9 is rotatably disposed. The spool 9 includes a
first spool section 9a and a second spool section 9b that may be
coaxially and rotatably fitted into a left end portion of the first
spool portion 9a. The first spool section 9a includes a belt
winding portion 9a1, a flange portion 9a2 formed at the right end
of the belt winding portion 9a1, and a rotary shaft 9a3 extending
from the flange portion 9a2 in the axial direction. The second
spool section 9b includes a flange portion 9b1 and a rotary shaft
9b2 that extends from the flange portion 9b1 in the axial
direction.
[0041] An end portion 9a4 of the rotary shaft 9a3 of the first
spool section 9a may be supported by a cover 52 fixed to the side
wall 8c via a bush 50 such that the rotary shaft 9a3 rotates with
the bush 50. A lock gear 11 may be coaxially fitted to the rotary
shaft 9a3. Thus, similar to a conventional lock gear 11, the lock
gear 11 rotates together with the rotary shaft 9a3 when the lock
gear 11 is not prevented from rotating. The rotary shaft 9a3
rotates relative to the lock gear 11 when the lock gear 11 is
prevented from rotating. As shown in FIG. 3, the lock gear 11
includes a predetermined number of ratchet teeth 11a that may be
formed on the outer periphery of the lock gear 11 and in an annular
shape. Additionally, a cam hole 11b may be formed in a side surface
of the lock gear 11.
[0042] As shown in FIG. 2 and FIG. 3, a fly wheel 12 is
oscillatably supported by the lock gear 11. The fly wheel 12 may be
an inertia member composing the belt withdrawal sensor. The fly
wheel 12 of includes an inertial mass portion 12a and a ring
portion 12b. The inertial mass portion 12a includes a through hole
12d that a projecting pin 11c formed on the lock gear 11 may be
fitted such that the fly wheel 12 is oscillatably supported. An
engaging claw 12c may be formed upon the inertial mass portion 12a.
The ring portion 12b may be formed in an annular shape as shown in
FIGS. 4(a), 4(b), and FIG. 5.
[0043] An eccentric disk 13 may be fitted and fixed to the rotary
shaft 9a3 of the first spool section 9a. An eccentric gear 14 may
be supported on the eccentric disk 13 such that the eccentric gear
14 is rotatable relative to the eccentric disk 13.
[0044] The eccentric gear 14 includes a predetermined number of
external teeth 14a. The external teeth 14a can mesh with internal
teeth 15a of a ring gear 15. The ring gear 15 may be formed in the
casing 10 coaxially with the spool 9. The outer diameter of the
spool may be larger than the outer diameter of the eccentric gear
14. The eccentric gear 14 includes a first lever operation cam 16,
a second lever operation cam 17, and a third lever operation cam
18.
[0045] As shown in FIG. 3 and FIG. 4(a), rotatably supported on the
casing 10 may be a switching lever 19. The switching lever 19
includes an engaging lever 20 and a disengaging lever 21. The
switching lever 19 also includes a projection 22 and an engaging
arm 23 projecting toward the disengaging lever 21. The projection
22 may be engaged with either one of two first and second
concavities 24a, 24b as curves respectively formed in a switching
lever position control spring 24. The position control spring 24
may include a plate spring, thereby positioning the switching lever
19.
[0046] When the projection 22 engages the first concavity 24a, the
switching lever 19 may be placed and held at such a position that
the engaging lever 20 may contact the first lever operation cam 16.
The engaging arm 23 may be set at such a position such that the
engaging arm 23 may not engage with any one of the ratchet teeth
11a of the lock gear 11. Additionally, the seat belt retractor 3
may be set in a state such that the seat belt retractor 3 exercises
the ELR function. When the projection 22 is engaged with the second
concavity 24b, the switching lever 19 may be placed and held at a
position such that the disengaging lever 21 may contact the second
lever operation cam 17. Therefore, the engaging arm 23 may be set
at a position such that the engaging arm 23 may engage one of the
ratchet teeth 11a when the lock gear 11 rotates in the belt
withdrawing direction. Then, the engaging arm 23 may engage one of
the ratchet teeth 11a by the rotation of the lock gear 11 in the
belt withdrawing direction. Thus, rotation of the spool 9 in the
belt withdrawing direction may be prevented. Accordingly, the seat
belt retractor 3 may be set in a state such that the retractor 3
exercises the ALR function.
[0047] The eccentric disk 13, the eccentric gear 14, the ring gear
15, the first lever operation cam 16, the second lever operation
cam 17, the switching lever 19, and the switching lever position
control spring 24 operate together to function as an ELR-ALR
switching mechanism 25. Detailed structure and detailed operation
of the ELR-ALR switching mechanism 25 are described in the
publication JP-A-2004-262447 and thus can be readily understood
with reference to the publication. Therefore, these will be
omitted.
[0048] Similar to conventional webbing sensors, the fly wheel 12
may be arranged such that the engaging claw 12c can engage any one
of the predetermined number of the ratchet teeth 26. Therefore,
when the seat belt retractor 3 is not in operation (e.g., the seat
belt 4 is fully wound) and the seat belt 4 is withdrawn faster than
a predetermined speed, the fly wheel 12 may rotate together with
the lock gear 11. As a result, the fly wheel 12 may be held at a
position shown in FIG. 4(a) such that the engaging claw 12c may not
engage with the ratchet wheel 26. When the seat belt 4 withdrawn at
a relatively large acceleration exceeding the aforementioned
predetermined value, the fly wheel 12 may oscillate relative to the
rotation of the lock gear 11 due to inertial delay of the inertial
mass portion 12a. The fly wheel 12 may be set at a position shown
in FIG. 4(b) such that the engaging claw 12c may engage one of the
ratchet teeth 26. Therefore, when the seat belt 4 is rapidly
withdrawn, the rotation of the spool 9 in the belt withdrawing
direction may be prevented so as to not allow the withdrawal of the
seat belt 4.
[0049] Furthermore, as shown in FIG. 2 and FIG. 3, a vehicle sensor
27 may be used as a deceleration detecting mechanism and may be
attached to the side wall 8c. The vehicle sensor 27 may be a
conventional vehicle sensor and may include an inertia ball 28. The
inertial ball 28 may be actuated when a large deceleration is
applied to the vehicle such as the event of a vehicle collision. A
casing 29 may be attached to the side wall 8c to support the
inertia ball 28. An actuator 30 may be pivotally mounted to the
casing 29 and may be actuated by the actuation of the inertia ball
28. A cover 31 may be attached to the casing 29. The actuator 30
includes an engaging claw 30a. When the inertia ball 28 is not
actuated, the engaging claw 30a may be held at a position such that
the engaging claw 30a may not engage any of the ratchet teeth 11a
of the lock gear 11. When the inertia ball 28 is actuated, the
engaging claw 30a may be set at a position such that the engaging
claw 30a may engage one of the ratchet teeth 11a. When the engaging
claw 30a is not engaged with any one of the ratchet teeth 11a, the
lock gear 11 may rotate in both the belt winding direction and the
belt withdrawing direction. When the engaging claw 30a is engaged
with one of the ratchet teeth 11a, the lock gear 11 may be
prevented from rotating in the belt withdrawing direction.
[0050] Disposed on the side wall 8b may be a conventional
pretensioner 32. The rotary shaft 9b2 of the second spool section
9b may be rotatably supported by a casing 33 for the pretensioner
32. The pretensioner 32 may be actuated in the event of an
emergency. The operational force of the pretensioner 32 may be
transmitted to the second spool section 9b such that the spool 9
rotates in the belt winding direction. Therefore, the seat belt 4
may be wound up at an early stage of the emergency, thereby
increasing the belt tension.
[0051] Rotatably supported by the second spool section 9b may be a
conventional pawl 34. The pawl 34 may engage with one of a
predetermined number of teeth 35, that may be formed in the inner
periphery of the side wall 8b. When the first spool section 9a and
the lock gear 11 rotate in the belt withdrawing direction, the pawl
34 may be held at a position such that the pawl 34 may not engage
any one of the teeth 35. When the first spool section 9a rotates in
the belt withdrawing direction relative to the lock gear 11, the
pawl 34 may be set by a control member (not shown). The control
member may be controlled by a cam hole 11b of the lock gear 11 at a
position such that the pawl 34 may not engage one of the teeth 35.
When the pawl 34 is not engaged with the teeth 35, the second spool
section 9b may rotate in both the belt winding direction and the
belt withdrawing direction. When the pawl 34 is engaged with one of
the teeth 35, the second spool section 9b may not rotate at least
in the belt withdrawing direction. The pawl 34 and the teeth 35
work together to function as a locking mechanism of the present
disclosure. The lock gear 11 may include a lock actuation mechanism
of the present disclosure. The operation control of the pawl 34 by
the control member and the cam hole 11b is conventionally known and
easily structure. Additionally, these are not characterizing
portions of the present disclosure even though they are components
of the present disclosure. Therefore, the detailed descriptions
thereof will be omitted.
[0052] As shown in FIG. 2, a conventional torsion bar 36 may be
disposed to extend between the first and second spool sections 9a,
9b. Shown in FIG. 2, the right end portion 36a of the torsion bar
36 may be adapted to rotate with the first spool section 9a. Also
shown in FIG. 2, the left end portion 36b of the torsion bar 36 may
be adapted to rotate together with the second spool section 9b.
[0053] In the event of an emergency, the pawl 34 may engage one of
the teeth 35, thus preventing the second spool section 9b from
rotating in the belt withdrawing direction. Due to the inertia of
the occupant, the seat belt 4 may be withdrawn and the first spool
section 9a may begin to rotate in the belt withdrawing direction.
The torsion bar 36 may torsionally deform so as to absorb impact
energy applied to the occupant by the seat belt 4.
[0054] The seat belt retractor 3 is provided with an end lock
preventive mechanism for preventing an end lock as mentioned above
which may occur due to the operation of the actuator 30 of the
vehicle sensor 27 or the operation of the fly wheel 12 of the
webbing sensor.
[0055] As shown in FIG. 3 and FIG. 5, the end lock preventive
mechanism 37 for the vehicle sensor 27 includes an end lock
preventive lever 38 and an end lock preventive lever position
control spring 39. The end lock preventive lever control spring 39
includes a plate spring, an eccentric ring 13, and an eccentric
gear 14.
[0056] The end lock preventive lever 38 may be rotatably supported
on the casing 10. The end lock preventive lever 38 includes a
locking lever 40 and an unlocking lever 41. The end lock preventive
lever 38 also includes a projection 42 and an end lock preventive
arm 43. The projection 42 may engage the first and/or second
concavities 39a, 39b as curves formed in an end lock preventive
lever position control spring 39. Therefore, the end lock
preventive lever 38 may be positioned.
[0057] As shown in FIG. 5, when the projection 42 engages the first
concavity 39a, the end lock preventive lever 38 may be held at a
position such that the third lever operation cam 18 may contact the
locking lever 40 and may not contact the unlocking lever 41. As a
result, the end lock preventive arm 43 may be set at an end lock
prevention canceling position shown by a solid line in FIG. 5 and
the actuator 30 of the vehicle sensor 27 may be set to an operable
state. When the projection 42 is engages the second concavity 39b,
the end lock preventive lever 38 may be positioned and held such
that the third lever operation cam 18 may contact the unlocking
lever 41 and may not contact the locking lever 40. Therefore, the
end lock preventive arm 43 may be set at an end lock preventing
position shown by a two-dot chain line in FIG. 5. In the end lock
preventing position, the end lock preventive arm 43 may contact the
actuator 30 of the vehicle sensor 27, thereby locking the actuator
30 at an inoperable position. Accordingly, the actuator 30 may be
set in an inoperable state.
[0058] As shown in FIG. 3 and FIGS. 6(a), 6(b), an end lock
preventive mechanism 44 for the fly wheel 12 as the webbing sensor
includes a pair of stoppers 45, 46, a ring portion 12b of the fly
wheel 12, an eccentric ring 13, an eccentric gear 14, a pair of
guide grooves 47, 48, and a cam groove 49. The pair of guide
grooves 47, 48 may be spaced from each other in a circumferential
direction by an angle 180.degree.. Therefore, the pair of guide
grooves 47,48 may oppose each other and extend linearly.
Additionally, the cam groove 49 may be formed in the casing 10.
[0059] The pair of stoppers 45, 46 may be formed in a similar
configuration. Each stopper includes a contact portion 45a, 46a
that may contact the inner periphery of the ring portion 12b of the
fly wheel 12. A guided portion 45b, 46b may be guided to move along
one of the pair of guide grooves 47, 48. A cam follower 45c, 46c
may move along the cam groove 49.
[0060] The guide grooves 47, 48 of the eccentric gear 14 may guide
the stoppers 45, 46 such that the guided portions 45b, 46b of the
stoppers 45, 46 move in the radial direction of the eccentric gear
17. The stoppers 45, 46 include an oscillation preventive member
according to the present disclosure.
[0061] The cam groove 49 may include a pair of small-diameter
circular grooves 49a, 49b that may be coaxial with a circular hole
10a of the casing 10. The bush 50 may pass through the circular
hole 10a. Additionally, there may be a pair of large-diameter
circular grooves 49c, 49d that may be coaxial with the circular
hole 10a. The small-diameter circular grooves 49a, 49b and the
large-diameter circular grooves 49c, 49d may form a closed loop.
When arranged in a closed loop, the pair of small-diameter circular
grooves 49a, 49b and the pair of large-diameter circular grooves
49c, 49d may be alternately arranged in a circumferential direction
of the circular hole 10a. The lengths in the circumferential
direction of the pair of small-diameter circular grooves 49a, 49b
may be equal to each other. The lengths in the circumferential
direction of the pair of large-diameter circular grooves 49c, 49d
may be equal to each other and shorter than the lengths in the
circumferential direction of the small-diameter circular grooves
49a, 49b. The cam groove 49 may be formed of an endless-type inner
peripheral wall 49e and an endless-type outer peripheral wall 49f.
The endless-type outer peripheral wall 49f may extend from the side
wall of the casing 10 in the axial direction of the spool 9.
[0062] The cam follower 45c of the stopper 45 may be positioned
within the large-diameter circular groove 49c when the seat belt 4
is fully wound. The contact portion 45a may contact the inner
periphery of the ring portion 12b, thereby pressing the ring
portion 12b in the outer radial direction.
[0063] Similarly, the cam follower 46c of the other stopper 46 may
be positioned within the large-diameter circular groove 49d when
the seat belt 4 is fully wound. The contact portion 46a may contact
the inner periphery of the ring portion 12b, thereby pressing the
ring portion 12b in the outer radial direction.
[0064] Furthermore, the cam follower 45c may be positioned within
the small-diameter circular groove 49a when the other cam follower
46c is positioned within the other small-diameter circular groove
49b. Additionally, the cam follower 45c may be positioned within
the large-diameter circular groove 49c when the other cam follower
46c is positioned within the other large-diameter circular groove
49d. More particularly, the positions of the pair of cam followers
45c, 46c may be controlled in synchronization with each other.
Therefore, the contact portions 45a, 46a of the pair of stoppers
45, 46 may contact the inner periphery of the ring portion 12b
thereby pressing the inner periphery in the outer radial direction
simultaneously. Since the inner periphery of the ring portion 12b
may be pressed by the contact portions 45a, 46a, the fly wheel 12
may be set in a locked state where the fly wheel 12 can not
oscillate. The eccentric gear 14, the guide grooves 47, 48, and the
cam groove 49 may work together to function as an oscillation
preventive member control mechanism according to the present
disclosure.
[0065] A conventional spring mechanism 51 may be attached to the
casing 10. The biasing force of the spring mechanism 51 may be
transmitted to the spool 9 via the bush 50. As a result, the spring
mechanism 51 may bias the spool 9 in the belt winding direction.
Due to the biasing force of the spring mechanism 51, the seat belt
4 may be fully wound onto the spool 9 when the seat belt is not
used.
[0066] Hereafter, respective actions of the ELR-ALR switching
mechanism 25, the end lock preventive mechanism 37 for the vehicle
sensor 27, and the end lock preventive mechanism 44 for the fly
wheel 12 will be described.
[0067] FIGS. 7(a)-7(d) and FIGS. 8(a)-8(b) show the switching
actions from the ELR function mode to the ALR function mode. FIGS.
9(a)-9(d) and FIGS. 10(a) and 10(b) are illustrations for showing
the actions of the end lock preventive mechanism 37 for the vehicle
sensor 27. FIGS. 11(a) and 11(b), FIGS. 12(a) and 12(b), and FIG.
13(a) are illustrations for showing the actions of the end lock
preventive mechanism 44 for the fly wheel 12. FIGS. 11(c) and
11(d), FIGS. 12(c) and 12(d), and FIG. 13(b) are illustrations for
explaining respective behaviors of the pair of stoppers 45, 46 and
the cam groove 49 for controlling the actions of the end lock
preventive mechanism 44 for the fly wheel 12.
[0068] When the seat belt 4 is fully wound by the seat belt
retractor 3, the seat belt retractor 3 may be set by the ELR-ALR
switching mechanism 25 in a state such that the seat belt retractor
3 can exercise the ELR mechanism. The switching lever 19 may be
positioned such that the projection 22 may engage the first
concavity 24a of the switching lever position control spring 24 as
shown in FIG. 7(a). When the switching lever 19 is in this
position, the first lever operation cam 16 may contact the engaging
lever 20 according to the position of the eccentric gear 14.
Additionally, the first lever operation cam 16 may not contact the
disengaging lever 21. Furthermore, the second lever operation cam
17 may not contact the engaging lever 20 and/or the disengaging
lever 21.
[0069] As shown in FIG. 9(a), the end lock preventive lever 38 may
be positioned such that the projection 42 may engage the second
concavity 39b of the end lock preventive lever position control
spring 39. When the end lock preventive lever 38 is in this
position, the third lever operation cam 18 may contact the
unlocking lever 41 according to the position of the eccentric gear
14. Additionally, the third lever operation cam 18 may not contact
the locking lever 40. Therefore, the end lock preventive arm 43 of
the end lock preventive lever 38 may be set at an end lock
preventing position such that the actuator 30 enters an inoperative
state.
[0070] The contact portions 45a, 46a of the pair of stoppers 45, 46
of the end lock preventive mechanism 44 may not press the inner
periphery of the ring portion 12b of the fly wheel 12.
[0071] As the seat belt 4 begins to be withdrawn from the seat belt
retractor 3, the eccentric gear 14 may eccentrically rotate at a
reduced speed in the belt winding direction. Therefore, as shown in
FIG. 11(c), the cam followers 45c, 46c of the pair of stoppers 45,
46 may enter the large-diameter circular grooves 49c, 49d. As shown
in FIG. 11(a), the respective contact portions 45a, 46a may press
the inner periphery of the ring portion 12b such that the fly wheel
12 may be locked from oscillating. Thus, the fly wheel 12 may enter
an inoperable state.
[0072] As the seat belt 4 is further withdrawn, the pair of cam
followers 45c, 46c may rotate in the belt winding direction. As
shown in FIG. 11(d), the cam followers 45c, 46c may reach the ends
of the large-diameter circular grooves 49c, 49d. As shown in FIG.
11(b), when the cam followers 45c, 46c are positioned within the
large-diameter circular grooves 49c, 49d, the contact portions 45a,
46a may continue pressing the ring portion 12b. Therefore, a lock
of the fly wheel 12 may be maintained.
[0073] As the seat belt 4 is further withdrawn, the pair of cam
followers 45c, 46c may further rotate in the belt winding
direction. As a result, the cam followers 45c, 46c may disengage
the large-diameter circular grooves 49c, 49d and engage the
small-diameter circular grooves 49a, 49b as shown in FIG. 12(c).
Accordingly, as shown in FIG. 12(a), the contact portions 45a, 46a
may move apart from the inner periphery of the ring portion 12b
such that the lock of the fly wheel 12 is cancelled. Therefore, the
fly wheel 12 may oscillate and enter an operable state.
[0074] The rotational angle of the eccentric gear 14 from when the
seat belt 4 is fully wound state to when the cam followers 45c, 46c
enter the small-diameter circular grooves 49a, 49b is about
60.degree.. Therefore, the amount of seat belt 4 withdrawn is
slight. By the withdrawal of a slight amount of the seat belt 4
from the fully wound state, the fly wheel 12 may switch from an
inoperable state to an operable state. The fly wheel 12 can
exercise the same function as a conventional webbing sensor.
Accordingly, when the seat belt 4 is withdrawn at a speed higher
than a predetermined belt withdrawal speed, the fly wheel 12 may be
actuated. As a result, the engaging claw 12c may engage one of the
ratchet teeth 26, thereby preventing the lock gear 11 from rotating
in the belt withdrawing direction. Therefore, since the spool 9
rotates relative to the lock gear 11 in the belt withdrawing
direction, the pawl 34 may engage one of the internal teeth 35 of
the side wall 8b. Thus, the second spool section 9b may be
prevented from rotating in the belt withdrawing direction. As a
result, the withdrawal of the seat belt 4 is prevented.
[0075] As shown in FIG. 9(b), when the pair of cam followers 45c,
46c enter the small-diameter circular grooves 49a, 49b, the third
lever operation cam 18 may contact the unlocking lever 41 of the
end lock preventive lever 38. As the seat belt 4 is further
withdrawn, the third lever operation cam 18 may press the unlocking
lever 41 as shown in FIG. 9(c). Thus, the end lock preventive lever
38 may be pivotally moved so that the projection 42 may disengage
the second concavity 39b of the end lock preventive lever position
control spring 39 and may engage the first concavity 39a.
Therefore, the end lock preventive arm 43 of the end lock
preventive lever 38 may be set and held at the end lock prevention
cancelling position such that the actuator 30 of the vehicle sensor
27 enters an operable state. Similar to a conventional vehicle
sensor, the actuator 30 may be actuated by movement of the inertia
ball 28 in the event of an emergency where a large deceleration is
applied to the vehicle. Thus, the engaging claw 30a may engage one
of the ratchet teeth 11a of the lock gear 11. Due to rotation of
the lock gear 11 in the belt withdrawing direction, one of the
ratchet teeth 11a may engage the engaging claw 30a. Therefore, the
lock gear 11 may be prevented from rotating in the belt withdrawing
direction. As a result, since the spool 9 rotates relative to the
lock gear 11 in the belt withdrawing direction, the pawl 34 may
engage one of the internal teeth 35 of the side wall 8b. As a
result, the second spool section 9b may be prevented from rotating
in the belt withdrawing direction. FIG. 9(c) shows the actuator 30
in an operative state.
[0076] Since the first spool section 9a further rotates in the belt
withdrawing direction as the seat belt 4 is withdrawn by inertia of
the occupant, the torsion bar 36 may torsionally deform similar to
a conventional torsion bar. The torsional deformation of the
torsion bar 36 absorbs impact energy applied to the occupant by the
seat belt 4.
[0077] As the seat belt 4 withdraws further, the third lever
operation cam 18 may pass through the end lock preventive lever 38
as shown in FIG. 12(b). The end lock preventive lever 38 may be
held at the end lock prevention cancelling position such that the
vehicle sensor 27 maintains an operable state. As shown in FIG.
12(d), the pair of cam followers 45c, 46c may further rotate in the
belt winding direction, entering the small-diameter circular
grooves 49a, 49b. Therefore, as shown in FIG. 12(b), the contact
portion 45a may be held in a position apart from the inner
periphery of the ring portion 12b. As a result, the fly wheel 12
may maintain an operable state.
[0078] As the seat belt 4 withdraws further, the eccentric gear 14
may rotate in the belt winding direction. Additionally, the first
lever operation cam 16 may move towards the engaging lever 20 of
the switching lever 19. Meanwhile, the vehicle sensor 27 and the
fly wheel 12 maintain their operable states.
[0079] Before the seat belt 4 is fully withdrawn, as shown in FIG.
7(b), the first lever operation cam 16 may contact and press the
engaging lever 20 of the switching lever 19. As shown in FIG. 7(c),
the switching lever 19 may pivotally move such that the projection
22 of the switching lever 19 engages the second concavity 24b of
the switching lever position control spring 24. Accordingly, the
switching lever 19 may be positioned. More particularly, the
engaging arm 23 of the switching lever 19 may be held at a position
such that the engaging arm 23 may engage the ratchet teeth 11a of
the lock gear 1. Accordingly, the seat belt retractor 3 may be
switched from the ELR function mode to the ALR function mode.
[0080] As the seat belt 4 is fully withdrawn, as shown in FIG.
7(d), one of the ratchet teeth 11a of the lock gear 11 engage the
engaging arm 23. Additionally, the vehicle sensor 27 may maintain
an operable state as shown in FIG. 9(d). The cam followers 45c, 46c
of the stoppers 45, 46 may be positioned at an end of the
small-diameter circular grooves 49a, 49b on the side of the
large-diameter circular grooves 49c, 49d, as shown in FIG. 13(b).
The contact portions 45a, 46a may be spaced apart from the inner
periphery of the ring portion 12b as shown in FIG. 13(a).
Therefore, the fly wheel 12 may maintain an operable state.
[0081] As the spool 9 rotates in the belt winding direction from a
state that the seat belt 4 is fully withdrawn, a certain amount of
the seat belt 4 may be wound onto the spool 9. The lock gear 11 may
also rotate in the belt winding direction. When the lock gear 11
rotates in the belt winding direction, the engaging arm 23 slides
on the ratchet teeth 11a and may not engage the ratchet teeth 11a.
Therefore, the seat belt 4 may be smoothly wound onto the spool 9.
If an attempt is made to withdraw the seat belt 4 after a
predetermined amount of the seat belt 4 is wound, both the spool 9
and the lock gear 11 may rotate in the belt withdrawing direction.
As the spool 9 and lock gear 11 rotate in the belt withdrawing
direction, one of the ratchet teeth 11a of the lock gear 11 may
engage the engaging arm 23. Therefore, the spool 9 and the lock
gear 11 may be prevented from rotating in the belt withdrawing
direction such that the seat belt 4 may not be withdrawn. The seat
belt retractor 3 exercises the ALR function. Due to rotation of the
spool 9 in the belt winding direction, the eccentric gear 14 nay
rotate in the belt withdrawing direction.
[0082] As the seat belt 4 is further wound, the third lever
operation cam 18 may gradually come closer to the locking lever 40
of the end lock preventive lever 38. As shown in FIG. 10(a), by
further winding of the seat belt 4 the third lever operation cam 18
may contact and press the locking lever 40. Then, as shown in FIG.
10(b), the end lock preventive lever 38 may pivotally move such
that the projection 42 of the end lock preventive lever 38 may
disengage the first concavity 39a and may engage the second
concavity 39b of the end lock preventive lever position control
spring 39. Therefore, the end lock preventive arm 43 of the end
lock preventive lever 38 may be set and held at the end lock
preventing position such that the actuator 30 of the vehicle sensor
27 enters an inoperable state. Since the seat belt retractor 3 is
set in the ALR function mode, withdrawal of the seat belt 4 may be
prevented in the event of an emergency.
[0083] As the seat belt 4 is further wound and nears being fully
wound, the second lever operation cam 17 may contact and press the
disengaging lever 21 of the switching lever 19. As shown in FIG.
8(b), the switching lever 19 may be pivotally moved such that the
projection 22 of the switching lever 19 may disengage the second
concavity 24b and may engage the first concavity 24a of the
switching lever position control spring 24. Therefore, the engaging
arm 23 may be set at a position such that the engaging arm 23 may
not engage the ratchet teeth 11a of the lock gear 11. Accordingly,
the seat belt retractor 3 may be switched from the ALR function
mode to the ELR function mode.
[0084] As shown in FIG. 11(d), as the seat belt 4 is further wound,
the cam followers 45c, 46c of the stoppers 45, 46 may enter the
large-diameter circular grooves 49c, 49d from the small-diameter
circular grooves 49a, 49b. Therefore, the contact portions 45a, 46a
may contact and press the inner periphery of the ring portion 12b,
locking the fly wheel 12 so that the fly wheel 12 enters an
inoperable state.
[0085] As the seat belt 4 is fully wound, the rotation of the spool
9 may be stopped and the rotation of the eccentric gear 14 may also
be stopped while the vehicle sensor 27 and the fly wheel 12 enter
inoperable states.
[0086] When the seat belt is fully or nearly fully wound, the pair
of stoppers 45, 46 may move in a radial direction passing through
the rotational center of the spool 4. The stoppers 45, 46 are thus
set at the oscillation preventing position where the stoppers 45,
46 may press the inner periphery of the ring portion 12b.
Therefore, the oscillation of the fly wheel 12 of the webbing
sensor may be prevented so that the fly wheel 12 may be held at an
inoperative position. Additionally, an end lock due to the webbing
sensor can be prevented by a simple structure including the
stoppers 45, 46.
[0087] The eccentric gear 14 may be used as a movement control
member for controlling the pair of stoppers 45, 46. The pair of
stoppers 45, 46 may move between an oscillation preventing position
and an oscillation allowing position. In the oscillation preventing
position, the stoppers 45, 46 may press the inner periphery of the
ring portion 12b. In the oscillation allowing position, the
stoppers 45, 46 may not press the inner periphery of the ring
portion 12b. Therefore, the structure for controlling the actuation
of the stoppers may be made both simpler and more compact.
[0088] The eccentric gear 14 may be a flat member. Therefore, a
compact design of the movement control member can be further
effectively achieved. Additionally, an exclusive control member for
controlling the pair of stoppers 45, 46 is not required.
Accordingly, the parts count of the seat belt retractor of the
automatic locking type can be reduced, even with the function of
preventing an end lock due to the webbing sensor.
[0089] Further, the fly wheel 12 may be included with the ring
portion 12b, and the inner periphery of the ring portion 12b may be
pressed by the stoppers 45, 46 thereby preventing actuation of the
fly wheel 12. Thus, a conventional fly wheel 12 can be employed
without significant design change. Additionally, the oscillation
preventive mechanism may be a simple structure since all that is
required is to simply press the ring portion 12b by the stoppers
45, 46. In addition, since the stoppers 45, 46 are used, the seat
belt retractor can be flexibly and inexpensively adapted to various
layouts of seat belt units 1. The various layouts may require a
lower parts count by suitably setting the movement distance of the
stoppers 45, 46 relative to the eccentric gear 14.
[0090] Therefore, end locks in the seat belt retractor 3 can be
effectively prevented and operability of the seat belt 4 by the
occupant may be improved.
[0091] Although the end lock preventive mechanism 44 may be
provided with the pair of stoppers 45, 46 and the pair of the guide
grooves 47, 48, the present disclosure is not limited thereto. For
example, two or more stoppers for pressing the ring portion 12b and
two or more guide grooves for guiding the stoppers may be included.
The respective stoppers and the respective guide grooves may be
formed at any positions in the circumferential direction of the
eccentric gear 14. However, it is preferable to dispose the
stoppers and the guide grooves at equal spaces in the
circumferential direction of the eccentric gear 14. Then, the ring
portion 12b may be pressed equally along the circumferential
direction.
[0092] Additionally, as shown in FIG. 14, the pair of stoppers 45,
46 may be adapted to press in outward radial directions .alpha.,
.beta. relative to the eccentric gear 14 by an elastic biasing
member 53. Accordingly, the ring portion 12b of the fly wheel 12
can be locked by a larger force. Therefore, the pair of stoppers
45, 46 and the elastic biasing member 53 may be integrally formed
from a resin or a metal. Alternatively, the pair of stoppers 45, 46
and the elastic biasing member 53 may be formed separately and the
pair of stoppers may be connected by the elastic biasing member
53.
[0093] Although both of the two end lock preventive mechanisms 37,
44 are included in the seat belt retractor of the aforementioned
embodiment, only the end lock preventive mechanism 44 for
preventing an end lock due to the fly wheel 12 may be included.
[0094] The present disclosure is not limited to a seat belt
retractor including the ELR function and the ALR function as in the
aforementioned embodiments. The present disclosure can be adapted
to a seat belt retractor having only the ELR function. Furthermore,
the aforementioned embodiments are just illustrative examples for
carrying out the seat belt retractor of the present disclosure.
Therefore, the respective components of the seat belt retractor may
be vary within a scope of claims of the present invention.
[0095] The seat belt retractor and the seat belt apparatus of the
present disclosure are suitably used as a seat belt retractor in
that an end lock due to a belt withdrawal sensor may occur, and a
seat belt apparatus employing the same.
[0096] The priority application, Japanese Patent Application No.
2007-229006, filed Sep. 4, 2007 including the specification,
drawings, claims and abstract, is incorporated herein by reference
in its entirety.
[0097] Given the disclosure of the application, one versed in the
art would appreciate that there may be other embodiments and
modifications within the scope and spirit of the application.
Accordingly, all modifications attainable by one versed in the art
from the present disclosure within the scope and spirit of the
present application are to be included as further embodiments of
the present application. The scope of the present application is to
be defined as set forth in the following claims
* * * * *