U.S. patent application number 12/230067 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 | 20090057471 12/230067 |
Document ID | / |
Family ID | 40184920 |
Filed Date | 2009-03-05 |
United States Patent
Application |
20090057471 |
Kind Code |
A1 |
Hiramatsu; Koji ; et
al. |
March 5, 2009 |
Seat belt retractor
Abstract
A seat belt retractor includes a seat belt, a spool, and an
emergency locking mechanism for preventing the spool from rotating
in a belt withdrawal direction. The emergency locking mechanism
allows rotation of the spool not in operation and prevents the
rotation of the spool in the belt withdrawal direction when in
operation. A lock gear includes ratchet teeth on an outer periphery
of the emergency locking mechanism arranged in an annular shape.
The lock gear rotates with the spool when the emergency locking
mechanism is not in operation and actuates the locking mechanism
when the emergency locking mechanism is in operation. A vehicle
sensor includes an engaging claw and detects a vehicle deceleration
larger than a predetermined deceleration. The engaging claw engages
with one of the ratchet teeth to prevent rotation of the lock gear
in the belt withdrawal direction.
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: |
40184920 |
Appl. No.: |
12/230067 |
Filed: |
August 22, 2008 |
Current U.S.
Class: |
242/396.1 |
Current CPC
Class: |
B60R 22/405 20130101;
B60R 2022/4666 20130101; B60R 2022/468 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 |
2007-229005 |
Claims
1. A seat belt retractor, comprising: a spool that is rotatably
supported by a frame to wind up a seat belt; an emergency locking
mechanism for detecting a vehicle deceleration larger than a
predetermined threshold, preventing the spool from rotating in a
belt withdrawal direction, the emergency locking mechanism
comprising: at least one locking mechanism allowing rotation of the
spool when the emergency locking mechanism is not in operation and
preventing the rotation of the spool in the belt withdrawal
direction when the emergency locking mechanism is in operation; a
lock gear comprising ratchet teeth on an outer periphery of the
emergency locking mechanism and arranged in an annular shape, the
lock gear rotating together with the spool when the emergency
locking mechanism is not in operation and actuating the locking
mechanism when the emergency locking mechanism is in operation
creating a relative rotation between the lock gear and spool; and a
vehicle sensor comprising an engaging claw and detecting a vehicle
deceleration larger than the predetermined deceleration in the
event of an emergency, the vehicle sensor actuated to engage the
engaging claw with one of the ratchet teeth of the lock gear to
prevent rotation of the lock gear in the belt withdrawal direction,
creating a relative rotation between the spool and the lock gear;
and a first end lock preventive mechanism for preventing the
engaging claw of the vehicle sensor from engaging with one of the
ratchet teeth of the lock gear when the seat belt is fully or
nearly fully wound by the spool, the first end lock preventive
mechanism comprising: an end lock preventive member disposed on the
frame and set at a locking position where the end lock preventive
member does not allow the engaging claw of the vehicle sensor to be
engaged with one of the ratchet teeth of the lock gear when the
seat belt is fully or nearly fully wound and is set at a
non-locking position where the end lock preventive member allows
the engaging claw of the vehicle sensor to be engaged with one of
the ratchet teeth of the lock gear other than when the seat belt is
fully or nearly fully wound; and a control element that sets the
end lock preventive member at the locking position when the seat
belt is fully or nearly fully wound and sets the end lock
preventive member at the non-locking position when the seat belt is
not fully or nearly fully wound.
2. The seat belt retractor as claimed in claim 1, further
comprising an automatic locking mechanism that is actuated when the
seat belt is fully withdrawn and prevents the withdrawal of the
seat belt by winding the seat belt after the seat belt is fully
withdrawn until a certain amount of the seat belt is wound, and a
lock switching mechanism for switching an emergency locking
function mode in which an emergency locking function by the
emergency locking mechanism is exercised and an automatic locking
function mode such that an automatic locking function by the
automatic locking mechanism is exercised, wherein the control
element is disposed on a control member of the lock switching
mechanism.
3. The seat belt retractor as claimed in claim 2, wherein the lock
switching mechanism comprises 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 and at a speed lower than the
rotation speed of the spool and that has switching lever control
cam member for switching the setting position of the switching
lever, wherein the control member of the lock switching mechanism
is composed of the eccentric gear and the end lock preventive
member is composed of an end lock preventive lever that is
selectively set at either of the locking position or the un-locking
position, and wherein the control element is an end lock preventive
member control cam for switching the setting position of the end
lock preventive lever.
4. A seat belt retractor as claimed in claim 3, further comprising
a webbing sensor that is pivotally disposed on the lock gear and
that detects a withdrawal acceleration larger than normal
withdrawal acceleration for wearing the belt when the seat belt is
rapidly withdrawn and is thus actuated to prevent the rotation of
the lock gear in the belt withdrawing direction so as to create a
relative rotation between the spool and the lock gear, and a second
end lock preventive mechanism for preventing the actuation of the
webbing sensor when the seat belt is fully or nearly fully
wound.
5. A seat belt retractor as claimed in claim 4, wherein the second
end lock preventive mechanism has an actuation preventive member
that is controlled its actuation by the eccentric gear and prevents
the actuation of the webbing sensor when the belt is fully or
nearly fully wound.
6. A seat belt retractor as claimed in claim 5, wherein the second
end lock preventive mechanism further includes a ring member
disposed on the webbing sensor, and wherein said actuation
preventive member is a stopper that presses the ring member to
prevent the actuation of the webbing sensor when the seat belt is
fully or nearly fully wound.
7. A seat belt retractor as claimed in claim 6, wherein the stopper
is provided with a stopper biasing means for biasing the stopper in
such a direction that the stopper presses the ring member.
8. A seat belt apparatus comprising: a seat belt for restraining an
occupant; a seat belt retractor for winding up the seat belt while
allowing the withdrawal of the seat belt, the seat belt retractor
actuated in the event of an emergency to prevent the withdrawal of
the seat belt; wherein the retractor includes a spool that is
rotatably supported by a frame to wind up the seat belt and an
emergency locking mechanism for detecting a vehicle deceleration
larger than a predetermined threshold, preventing the spool from
rotating in a belt withdrawal direction, the emergency locking
mechanism comprising: at least one locking mechanism allowing
rotation of the spool when the emergency locking mechanism is not
in operation and preventing the rotation of the spool in the belt
withdrawal direction when the emergency locking mechanism is in
operation; and a lock gear comprising ratchet teeth on an outer
periphery of the emergency locking mechanism and arranged in an
annular shape, the lock gear rotating together with the spool when
the emergency locking mechanism is not in operation and actuating
the locking mechanism when the emergency locking mechanism is in
operation creating a relative rotation between the lock gear and
spool; and a vehicle sensor including an engaging claw and
detecting a vehicle deceleration larger than the predetermined
deceleration in the event of an emergency, the vehicle sensor
actuated to engage the engaging claw with one of the ratchet teeth
of the lock gear to prevent rotation of the lock gear in the belt
withdrawal direction, creating a relative rotation between the
spool and the lock gear; and a first end lock preventive mechanism
for preventing the engaging claw of the vehicle sensor from
engaging with one of the ratchet teeth of the lock gear when the
seat belt is fully or nearly fully wound by the spool, the first
end lock preventive mechanism comprising: an end lock preventive
member disposed on the frame and set at a locking position where
the end lock preventive member does not allow the engaging claw of
the vehicle sensor to be engaged with one of the ratchet teeth of
the lock gear when the seat belt is fully or nearly fully wound and
is set at a non-locking position where the end lock preventive
member allows the engaging claw of the vehicle sensor to be engaged
with one of the ratchet teeth of the lock gear other than when the
seat belt is fully or nearly fully wound; and a control element
that sets the end lock preventive member at the locking position
when the seat belt is fully or nearly fully wound and sets the end
lock preventive member at the non-locking position when the seat
belt is not fully or nearly fully wound. a tongue slidably
supported by the seat belt; and a buckle that is fixed to a vehicle
floor or a vehicle seat and to which the tongue can be detachably
latched.
Description
BACKGROUND
[0001] The present application relates generally to the field of a
seat belt retractor, for restraining an occupant with a seat belt
withdrawn from the seat belt retractor. More particularly, the
present application relates to a seat belt retractor in that an end
lock due to either a vehicle sensor or a vehicle sensor and a
webbing sensor may occur. The seat belt retractor may include at
least one emergency locking mechanism and an automatic locking
mechanism. The application also relates to the technical field of a
seat belt apparatus employing a seat belt retractor to restrain an
occupant with a seat belt withdrawn from the seat belt
retractor.
[0002] Conventionally, a seat belt apparatus installed in a vehicle
(e.g, an automobile) restrains an occupant in the event of an
emergency with a seat belt made of webbing to prevent the occupant
from being ejected out of their seat.
SUMMARY
[0003] One embodiment of the application relates to a seat belt
retractor, comprising at least one seat belt for restraining an
occupant; a spool that is rotatably supported by a frame to wind up
the seat belt, an emergency locking mechanism for detecting a
vehicle deceleration larger than a predetermined threshold,
preventing the spool from rotating in a belt withdrawal direction,
the emergency locking mechanism comprising at least one locking
mechanism allowing rotation of the spool when the emergency locking
mechanism is not in operation and preventing the rotation of the
spool in the belt withdrawal direction when the emergency locking
mechanism is in operation; a lock gear comprising ratchet teeth on
an outer periphery of the emergency locking mechanism and arranged
in an annular shape, the lock gear rotating together with the spool
when the emergency locking mechanism is not in operation and
actuating the locking mechanism when the emergency locking
mechanism is in operation creating a relative rotation between the
lock gear and spool; and a vehicle sensor comprising an engaging
claw and detecting a vehicle deceleration larger than the
predetermined deceleration in the event of an emergency, the
vehicle sensor actuated to engage the engaging claw with one of the
ratchet teeth of the lock gear to prevent rotation of the lock gear
in the belt withdrawal direction, creating a relative rotation
between the spool and the lock gear, a first end lock preventive
mechanism for preventing the engaging claw of the vehicle sensor
from engaging with one of the ratchet teeth of the lock gear when
the seat belt is fully or nearly fully wound by the spool, the
first end lock preventive mechanism comprising an end lock
preventive member disposed on the frame and set at a locking
position where the end lock preventive member does not allow the
engaging claw of the vehicle sensor to be engaged with one of the
ratchet teeth of the lock gear when the seat belt is fully or
nearly fully wound and is set at a non-locking position where the
end lock preventive member allows the engaging claw of the vehicle
sensor to be engaged with one of the ratchet teeth of the lock gear
other than when the seat belt is fully or nearly fully wound; and a
control element that sets the end lock preventive member at the
locking position when the seat belt is fully or nearly fully wound
and sets the end lock preventive member at the non-locking position
when the seat belt is not fully or nearly fully wound. A seat belt
retractor as claimed in claim 1, further comprising an automatic
locking mechanism which is actuated when said seat belt is fully
withdrawn and prevents the withdrawal of said seat belt on the way
of winding said seat belt after the seat belt is fully withdrawn
until a certain amount of the seat belt is wound, and a lock
switching mechanism for switching an emergency locking function
mode in which an emergency locking function by said emergency
locking mechanism is exercised and an automatic locking function
mode in which an automatic locking function by said automatic
locking mechanism is exercised, wherein said control element is
disposed on a control member of said lock switching mechanism.
BRIEF DESCRIPTION OF THE DRAWINGS
[0004] FIG. 1 shows a perspective view of a seat belt apparatus
comprising a seat belt retractor according to an exemplary
embodiment.
[0005] FIG. 2 is a sectional view of an exemplary embodiment of the
seat belt retractor.
[0006] 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.
[0007] FIGS. 4(a), 4(b) show illustrations of the behavior of the
webbing sensor of the seat belt retractor according to an exemplary
embodiment. FIG. 4(a) show illustration of an embodiment of the
webbing sensor in its inoperative state, and FIG. 4(b) shows an
illustration of an embodiment of the webbing sensor in its
operative state.
[0008] FIG. 5 shows an illustration of the ELR-ALR switching
mechanism, the end lock preventive mechanism for the vehicle
sensor, and the end lock preventive mechanism for the webbing
sensor of the seat belt retractor according to an exemplary
embodiment.
[0009] FIGS. 6(a) and 6(b) show illustrations of the end lock
preventive mechanism for the webbing sensor of the seat belt
retractor according to an exemplary embodiment. FIG. 6(a) is cross
sectional view of stoppers and FIG. 6(b) is cross sectional view of
cam grooves for controlling the stoppers according to an exemplary
embodiment.
[0010] FIGS. 7(a)-7(d) are illustrations of the switching action
from the ELR function mode to the ALR function mode according to an
exemplary embodiment.
[0011] FIGS. 8(a) and 8(b) are illustrations of another part of the
switching action from the ELR function mode to the ALR function
mode according to an exemplary embodiment.
[0012] FIGS. 9(a)-9(d) are illustrations of the end lock preventive
mechanism for the vehicle sensor according to an exemplary
embodiment.
[0013] FIGS. 10(a) and 10(b) are illustrations for showing another
part of the action of the end lock preventive mechanism for the
vehicle sensor.
[0014] FIGS. 11(a) and 11(b) are illustrations for showing a part
of the action of the end lock preventive mechanism for the fly
wheel used in this embodiment.
[0015] FIGS. 11(c) and 11(d) are illustrations for showing 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 used in this embodiment.
[0016] FIGS. 12(a) and 12(b) are illustrations for showing another
part of the action of the end lock preventive mechanism for the fly
wheel used in this embodiment.
[0017] FIGS. 12(c) and 12(d) are illustrations for showing 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 used in this embodiment.
[0018] FIG. 13(a) is an illustration showing a remaining part of
the action of the end lock preventive mechanism for the fly wheel
of the embodiment and FIG. 13(b) is an illustration showing 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 of this embodiment.
[0019] FIG. 14 is an illustration showing stoppers of exemplary
embodiment of the present disclosure.
DETAILED DESCRIPTION
[0020] According to one exemplary embodiment, a conventional seat
belt apparatus includes a seat belt retractor. The seat belt
retractor may be an emergency locking seat belt retractor (ELR) for
preventing the withdrawal of the seat belt. The seat belt retractor
may be an automatic locking seat belt retractor (ALR) that retracts
when the seat belt is fully withdrawn and prevents withdrawal of
the seat belt when the seat belt is wound up. The ALR actuation may
be cancelled when the seat belt is fully wound up.
[0021] The seat belt retractor can be similar to the retractor
disclosed in JP-A-2004-262447, which is herein incorporated by
reference in its entirety, and include a U-shaped frame, a belt
reel, and a shaft rotatably supported between left and right side
walls of the frame to widen the seat belt. A spring mechanism
attached to one of the side walls of the frame is constructed of a
spiral or similar spring for winding up a seat belt. A locking pawl
is a locking member that is engaged with one of the ratchet teeth
formed in the frame to prevent the spool from withdrawing. A
ratchet wheel actuates the locking pawl in the event of an
emergency. The retractor also includes an acceleration sensing
mechanism, an engaging claw, a lever (actuator) that engages one of
the ratchet teeth of the lock gear in the event of the emergency to
prevent withdrawal of the belt, an inertial mass rotatably
supported by the lock gear, ratchet teeth attached to the frame
with which the engaging claw is engaged, an internal gear ring
(ring gear) that includes internal teeth, an eccentric disk that
rotates with the spool and eccentrically from the center of the
spool, a control ring that rotates at a speed controlled by the
eccentric disk and includes external teeth that mesh with the
internal teeth of the ring gear, and an ALR lever for controlling
the ALR. The ALR function may be activated when the seat belt is
fully withdrawn and may be cancelled when the seat belt is fully
wound.
[0022] The seat belt retractor can use an ELR function when the
seat belt is not fully withdrawn. In an ELR mode a vehicle sensor
is activated in the event of an emergency. When a deceleration
outside of predefined values is detected, the actuator may be
engaged. The actuator interfaces with an engaging claw of the
actuator with one of the ratchet teeth of the lock gear so as to
prevent the lock gear from rotating in the belt withdrawal
direction. A relative rotation is created between the spool that is
about to rotate in the withdrawing direction as a result of the
inertia of the occupant and the lock gear that is prevented from
rotating in the withdrawal direction. The locking pawl
(corresponding to the locking mechanism of the present invention)
is activated by this rotation. The activated locking pawl may
engage with one of the ratchet wheels formed in the frame,
preventing the spool from rotating in the belt withdrawal
direction. Therefore, the withdrawal of the seat belt is stopped
and the forward movement of the occupant is prevented by restraint
of the seat belt.
[0023] The webbing sensor may be activated when the seat belt is
withdrawn faster than normal. More particularly, the lock gear
rapidly rotates during rapid withdrawal of the seat belt, actuating
the inertial mass. The engaging claw of the inertial mass is
engaged with one of the ratchet teeth, preventing the lock gear
from rotating in the withdrawal direction. Therefore, similar to
the operation of the vehicle sensor mentioned above, the rotation
of the spool in the withdrawal direction is locked, preventing the
withdrawal of the seat belt.
[0024] When the ALR function is used to fix a child seat to a
vehicle seat with the seat belt, the seat belt may be fully
withdrawn. The control ring of the automatic locking mechanism (ALR
mechanism) detects that the seat belt is fully withdrawn from its
eccentric rotation and activates the ALR lever. Upon activating the
ALR lever, the seat belt retractor may switch from the ELR mode to
the ALR mode. In the ALR mode, the rotation of the spool in the
belt withdrawal direction is locked by actuation of the ALR lever,
preventing the seat belt from being withdrawn until the seat belt
is fully wound. Once the seat belt is fully wound, the actuation of
the ALR lever is cancelled returning the seat belt retractor to the
ELR function mode.
[0025] When the occupant disengages the tongue from the buckle and
releases the tongue the seat belt, the seat belt may be rapidly
wound by the spool. The spool is biased in the belt winding
direction by the spring mechanism. When the seat belt is fully
wound the rotation of the spool is stopped. Accordingly, the
actuator of the vehicle sensor may rotate so that the engaging claw
interfaces with one of the ratchet teeth of the lock gear. The
rotation of the spool in the withdrawal direction is locked (e.g.,
an end lock) preventing withdrawal of the seat belt again.
[0026] According to another exemplary embodiment, to prevent an end
lock a seat belt retractor constructed such that a circular arc
pressing portion (stopper) may be disposed on the outer periphery
of a disk-like cam plate for exercising the ALR function as
described in JP-A-09-150712, which is herein incorporated by
reference in its entirety. The stopper moves in the rotational
direction of a lock gear by the rotation of the cam plate at a
reduced speed according to the rotation of the spool. The stopper
is positioned between a position allowing engagement and a
apposition preventing engagement. In the position allowing
engagement, the stopper allows an engaging pawl of a vehicle sensor
to be engaged with the ratchet teeth of the lock gear. Conversely,
in the position preventing engagement the stopper prevents the
engaging claw of the vehicle sensor from being engaged with the
ratchet teeth of the lock gear. When the seat belt is fully or
nearly fully wound by the spool, the stopper is set to the position
preventing engagement.
[0027] When the seat belt is fully wound, the stopper is set to the
position preventing engagement, preventing the engaging claw of the
vehicle sensor from being engaged with the ratchet teeth of the
lock gear. Therefore, an end lock caused by the engaging claw of
the vehicle sensor can be prevented.
[0028] The stopper is disposed on the outer periphery of the cam
plate and rotates together with the cam plate allowing the stopper
to be positioned in a region between the ratchet teeth of the lock
gear and the engaging claw of the vehicle sensor. This structure
may require the cam plate to be large. The large cam plate may
result in a large rotational trajectory of the outer periphery of
the cam plate, requiring a large space for movement. To prevent the
stopper from interfering with the engaging claw of the vehicle
sensor, the distance between the engaging claw and the ratchet
teeth may be larger than that of a conventional ELR.
[0029] The large distance between the engaging claw and the ratchet
teeth may make the moving distance of the engaging claw between the
inoperative position and the operative position large, making the
vehicle sensor large.
[0030] Due to the diversification of recent vehicles, the layout of
seat belt apparatuses to be installed in vehicles varies. The
combination of the operation range of the cam plate and the
operation range of the stopper generally depends on the layout of
the seat belt apparatus. However, the stopper for preventing the
engaging claw from being engaged with the ratchet teeth and the cam
plate for exercising the ALR function may be composed of the same
part. To adapt the seat belt retractor to various layouts of seat
belt apparatuses, each part composing the stopper and the cam plate
is used for each layout because the stopper and the cam plate are
composed of one part. Exclusive parts for each layout may be used,
increasing parts count and cost. For example, if there are nine
mounting layouts of seat belt apparatuses, then at least nine
exclusive parts are required. The exclusive parts may vary
corresponding to the different combinations of the operation ranges
of the cam plate and the operation ranges of the stopper.
[0031] The disclosed invention is made in consideration of the
aforementioned circumstances. An object of the disclosed invention
is to provide a seat belt retractor that can effectively prevent an
end lock due to an engaging pawl of a vehicle sensor using a
structure of reduced size and to provide a seat belt unit having
the same.
[0032] Another object of the present invention is to provide a seat
belt retractor that can be inexpensively adapted to various
mounting layouts with a lower parts count.
[0033] According to an exemplary embodiment, a seat belt retractor
may include at least a seat belt for restraining an occupant, a
spool rotatably supported by a frame to wind up the seat belt, and
an emergency locking mechanism. The emergency locking mechanism may
act to prevent the spool from rotating in the withdrawal direction
when a deceleration larger than normal is detected. The emergency
locking mechanism may include at least a locking mechanism that may
allow rotation of a spool when the emergency locking mechanism is
not in operation and may prevent the rotation of a spool in the
belt withdrawing direction when the emergency locking mechanism is
in operation. A lock gear comprising ratchet teeth may be formed on
an outer periphery of the emergency locking mechanism and may be
arranged in an annular shape. The lock gear may rotate together
with the spool when the emergency locking mechanism is not in
operation and may actuate the locking mechanism when the emergency
locking mechanism is in operation, creating a relative rotation
between the lock gear and spool. A vehicle sensor including an
engaging claw may detect a vehicle deceleration larger than a
predetermined deceleration such as in the event of an emergency. A
vehicle sensor may engage the engaging claw with one of the ratchet
teeth of the lock gear to prevent rotation of the lock gear in the
belt withdrawal direction, creating a relative rotation between the
spool and the lock gear. A first end lock preventive mechanism may
prevent the engaging claw from engaging with one of the ratchet
teeth of the lock gear when the seat belt is fully or nearly fully
wound. The first end lock preventive mechanism may include an end
lock preventive member disposed on the frame. The end lock
preventive member may be set at a locking position such that the
engaging claw of the vehicle sensor may not be engage the ratchet
teeth of the lock gear when the seat belt is fully or nearly fully
wound. The end lock preventive member may be set at a non-locking
position where the engaging claw of the vehicle sensor may engage
the ratchet teeth of the lock gear other than when said seat belt
is fully or nearly fully wound. Furthermore, a control element may
set the end lock preventive member at the locking position when the
seat belt is fully or nearly fully wound and may set the end lock
preventive member at the non-locking position when the seat belt is
not fully or nearly fully wound.
[0034] According to an exemplary embodiment, a seat belt retractor
includes an automatic locking mechanism. The automatic locking
mechanism may be actuated when the seat belt is fully withdrawn,
preventing withdrawal of the seat belt until a predetermined amount
of the seat belt is wound. The embodiment may further include a
lock switching mechanism for switching the seat belt retractor
between an emergency locking function mode and an automatic locking
function mode. Furthermore, the control element may be disposed on
a control member of the lock switching mechanism.
[0035] According to an exemplary embodiment, a seat belt retractor
includes a lock switching mechanism. The lock switching mechanism
may include a switching lever. The switching lever may be set at 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. An eccentric gear may
rotate when the spool rotates. A switching lever control cam member
may be used for switching the setting position of the switching
lever. The control member of the lock switching mechanism may
include the eccentric gear and an end lock preventive member The
end lock preventive member may include an end lock preventive lever
set at either the locking position or the un-locking position. The
control element may be an end lock preventive member control cam
for switching the setting position of the end lock preventive
lever.
[0036] According to an exemplary embodiment, a seat belt retractor
may include a webbing sensor that is pivotally disposed on the lock
gear. When a faster than normal withdrawal is detected, the webbing
sensor may actuate the lock gear. When actuated, rotation of the
lock gear in the belt withdrawal direction is prevented, creating a
relative rotation between the spool and the lock gear. The seat
belt retractor may also include a second end lock preventive
mechanism for preventing the actuation of the webbing sensor when
the seat belt is fully or nearly fully wound.
[0037] According to an exemplary embodiment, a seat belt retractor
includes a second end lock preventive mechanism. The second end
lock preventive mechanism may include an actuation preventive
member controlled by the eccentric gear. Therefore, actuation of
the webbing sensor may be prevented when the seat belt is fully or
nearly fully wound.
[0038] According to an exemplary embodiment, a seat belt retractors
second end lock preventive mechanism may include a ring member and
an actuation preventive member. The actuation preventive member may
be a stopper that presses the ring member in order to prevent
actuation of the webbing sensor when the seat belt is fully or
nearly fully wound.
[0039] According to an exemplary embodiment, a seat belt retractor
may include a stopper with a stopper biasing means. Therefore, the
stopper may be biased in such a direction that the stopper presses
the ring member.
[0040] According to an exemplary embodiment, a seat belt unit
includes at least a seat belt for restraining an occupant, a tongue
slidably supported by the seat belt, a seat belt retractor, and a
buckle fixed to a surface that the tongue may be detachably latched
onto. The seat belt retractor may perform at least one of winding
up the seat belt or withdrawal of the seat belt and may prevent
withdrawal of the seat belt in the event of an emergency.
[0041] In the embodiment of the seat belt retractor having the
aforementioned structure, the control element of the first end lock
preventive mechanism may set the end lock preventive member at a
locking position. While in the locking position, the engaging claw
of the vehicle sensor may be prevented from engaging the ratchet
teeth of the lock gear when the seat belt is fully or nearly fully
wound. Therefore, an end lock due to the vehicle sensor when the
seat belt is fully or nearly fully wound may be prevented.
Furthermore, since the end lock preventive member is not required
to rotate with the control member of the lock switching mechanism,
the end lock preventive member requires a smaller moving space.
[0042] Additionally, the end lock preventive member is not required
to pass between the ratchet teeth of the lock gear and the engaging
claw of the vehicle sensor. Thus, the end lock preventive member is
limited from interfering with the engaging claw. Therefore, the
distance between the engaging claw and the ratchet teeth is not
required to be changed as in conventional ELRs. More particularly,
the seat belt retractor of the present disclosure can be compact
even with the first end lock preventive mechanism.
[0043] Additionally, the distance between the engaging claw of the
vehicle sensor and the ratchet teeth of the lock gear is similar to
a conventional ELR or ALR without an end lock preventive mechanism.
Accordingly, the distance between the engaging claws inoperative
position and operative position is not required to be changed,
further limiting the vehicle sensors size. Even with the end lock
preventive mechanism, a conventional vehicle sensor can be used for
the seat belt retractor without any change, making manufacturing of
the seat belt retractor inexpensive.
[0044] Since the control member of the automatic locking mechanism
may be used for controlling the end lock preventive member, an
exclusive control member for the end lock preventive member is not
required. Furthermore, the number of parts in the automatic
locking-type seat belt retractor can be reduced even when the first
end lock preventive mechanism is included.
[0045] Additionally, the end lock preventive member includes an end
lock preventive lever disposed on the frame and an end lock
preventive member control cam disposed on the eccentric gear.
Therefore, the seat belt retractor can be flexibly and
inexpensively adapted to various layouts of seat belt apparatuses
using fewer parts. This may be accomplished by setting the position
of the end lock preventive member control cam relative to the
eccentric gear.
[0046] According to an exemplary embodiment, the lock switching
mechanism may include a switching lever and an eccentric gear. The
eccentric gear may further include a switching lever control cam
member for switching the setting position of the switching lever. A
control member of the lock switching mechanism may include the
eccentric gear. The end lock preventive member may include an end
lock preventive lever that may be set between the locking position
and non-locking position. The control element may be composed of
the end lock preventive member control cam for switching the
setting position of the end lock preventive lever. Therefore, an
end lock can be prevented with a simple structure.
[0047] According to an exemplary embodiment, in a seat belt
retractor including a webbing sensor the second end lock preventive
mechanism may prevent the actuation of the webbing sensor when the
seat belt is fully or nearly fully wound. Therefore, an end lock
due to either the vehicle sensor and/or the webbing sensor may be
prevented. Furthermore, an end lock when the seat belt is fully or
nearly fully wound may be prevented.
[0048] According to an exemplary embodiment, the second end lock
preventive mechanism may include an actuation preventive member
that may be controlled by rotation of the eccentric gear.
Therefore, actuation of the webbing sensor when the seat belt is
fully or nearly fully wound may be prevented. As a result, the
actuation of the webbing sensor can be effectively prevented.
[0049] Furthermore, since the second end lock preventive mechanism
includes a ring member and a stopper for preventing actuation of
the webbing sensor, a conventional webbing sensor can be employed
without significant design change. Therefore, the second end lock
preventive mechanism can have a simple structure because all that
is required is to simply press the ring member by the stopper.
[0050] According a further exemplary embodiment, a stopper may be
biased in a direction pressing the ring member by a stopper biasing
mechanism. Therefore, the ring member of the webbing sensor can be
locked with larger force.
[0051] According to a further exemplary embodiment, the seat belt
retractor of the present disclosure may be employed, preventing end
locks due to a vehicle sensor and/or a webbing sensor. Operability
of the seat belt is thus improved, enabling smooth and reliable use
by an occupant.
[0052] Referring to FIG. 1, a seat belt unit 1 includes a seat belt
retractor 3 fixed to a vehicle body near a vehicle seat 2, and a
seat belt 4 that may be withdrawn from the seat belt retractor 3. A
belt anchor 4a may be fixed to a vehicle floor or a vehicle seat 2.
The seat belt unit 1 may further include a deflection fitting 5 for
guiding a seat belt 4, a tongue 6 slidably supported by the seat
belt 4 and that may be guided by and extend from the deflection
fitting 5, and a buckle 7 fixed to the vehicle floor or the vehicle
seat 2 such that the tongue 6 can be inserted and detachably
latched.
[0053] The seat belt retractor 3 of this embodiment includes a
U-like frame 8. The U-like frame 8 includes a back wall 8a and left
and right side walls 8b, 8c extending from sides of the back wall
8a perpendicular to the extending direction of the back wall 8a as
shown in FIG. 2.
[0054] A spool 9 that a 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 the left end portion of the
first spool section 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 has a flange portion 9b1 and a rotary shaft 9b2
extending from the flange portion 9b1 in the axial direction.
[0055] An end portion 9a4 of the rotary shaft 9a3 may be supported
by a cover 52 of a casing 10 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. In this
embodiment, similar to the known lock gear 11, the lock gear 11
rotates 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 number of ratchet
teeth 11a formed on the outer periphery and in an annular shape.
The lock gear 11 also includes a cam hole 11b that may be formed in
a side surface of the lock gear 11.
[0056] As shown in FIG. 2 and FIG. 3, a fly wheel 12 that includes
a webbing sensor and is an inertia member may be oscillatably
supported by the lock gear 11. In this case, the fly wheel 12
includes an inertial mass portion 12a and a ring portion 12b. The
inertial mass portion 12a includes a through hole 12d such that a
projecting pin 11c formed on the lock gear 11 may be fit through,
oscillatably supporting a fly wheel 12. The inertial mass portion
12a may include an engaging claw 12c formed on 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.
[0057] An eccentric disk 12 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 may rotate relative to the eccentric disk 13.
[0058] The eccentric gear 14 includes 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 and may have an outer diameter larger than that of the
eccentric gear 14. The eccentric gear 14 may include a first lever
operation cam 16, a second lever operation cam 17, and a third
lever operation cam 18. The third lever operation cam 18 may
include a control element of the present disclosure.
[0059] Shown in FIG. 3 and FIG. 4(a), a switching lever 19 may be
rotatably supported on the casing 10. The switching lever 19 may
include an engaging lever 20 and a disengaging lever 21. The
switching lever 19 may also include a projection 22 and an engaging
arm 23 extending toward the disengaging lever 21. The projection 22
may engage with either of the first or second concavities 24a, 24b,
thereby positioning the switching lever 19.
[0060] More particularly, when the projection 22 engages the first
concavity 24a, the switching lever 19 may be held at such a
position that the engaging lever 20 may contact the first lever
operation cam 16. Therefore, the engaging arm 23 of the switching
lever 19 may be set such that the engaging arm 23 may not be
allowed to engage any of the ratchet teeth 11a of the lock gear 11.
As a result, the seat belt retractor 3 may be set at an emergency
locking mode where the seat belt retractor 3 may exercise the ELR
function. When the projection 22 engages the second concavity 24b,
the switching lever 19 may be placed and held such that the
disengaging lever 21 may contact the second lever operation cam 17.
In this case, the engaging arm 23 may be set such that the engaging
arm 23 engages one of the ratchet teeth 11a when the lock gear 11
rotates in the belt withdrawing direction. The engaging arm 23 may
engage one of the ratchet teeth 11a by rotating the lock gear 11 in
the belt withdrawing direction, thereby preventing rotation of the
spool 9 in the belt withdrawing direction. Accordingly, the seat
belt retractor 3 may be set to the automatic locking mode where the
retractor 3 exercises the ALR function of the automatic locking
mechanism (ALR mechanism). The eccentric disk 13, the eccentric
gear 14, the first and second lever operation cams 16, 17, and the
switching lever 19 cooperate together to function as the lock
switching mechanism of the present disclosure.
[0061] 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 cooperate together to function as an ELR-ALR
switching mechanism 25. According to an exemplary embodiment, the
structure and operation of the ELR-ALR switching mechanism 25 may
be similar to the switching mechanism described in the publication
JP-A-2004-262447, which is herein incorporated by reference in its
entirety.
[0062] Similar to conventional webbing sensors, the fly wheel 12
may be arranged such that the engaging claw 12c may engage any one
of the ratchet teeth 26. 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 at a speed equal to or lower than a normal
withdrawing speed, the fly wheel 12 may rotate with the lock gear
11. Additionally, 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 is withdrawn at a speed
exceeding the aforementioned normal withdrawing speed, the fly
wheel 12 may oscillate relative to the rotation of the lock gear 11
due to the inertial delay of the inertial mass portion 12a. The fly
wheel 12 may be set at a position as 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
as to restrict withdrawal of the seat belt 4.
[0063] 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 known
vehicle sensor. The vehicle sensor 27 includes an inertia ball 28
that may be actuated when a large deceleration is applied to the
vehicle. Furthermore, 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. Additionally, a cover 31 may be attached to
the casing 29. The actuator 30 may include 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 with 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 not engage the ratchet
teeth 11a. When the engaging claw 30a is not engaged with any of
the ratchet teeth 11a, the lock gear 11 may be allowed to rotate in
either the belt winding direction or the belt withdrawing
direction. When the engaging claw 30a engages with one of the
ratchet teeth 11a, the lock gear 11 may be prevented from rotating
in the belt withdrawing direction.
[0064] A known pretensioner 32 may be disposed on the side wall 8b.
The rotary shaft 9b2 of the second spool section 9b may be
rotatably supported by a casing 33. 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 may rotate 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.
[0065] A known pawl 34 may be rotatably supported by the second
spool section 9b. The pawl 34 can be engaged with one of the teeth
35 formed in the inner periphery of the opening of the side wall
8b. When the first spool section 9a and the lock gear 11 rotate
together in the belt withdrawing direction, the pawl 34 may hold at
a position such that the pawl 34 may not engage any 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) at such a position that the pawl 34 may
engage one of the teeth 35. When the pawl 34 is not engaged with
any of the teeth 35, the second spool section 9b may rotate in the
belt winding direction or the belt withdrawing direction. When the
pawl 34 is engaged with one of the teeth 35, the second spool
section 9b may not rotate in the belt withdrawing direction. The
pawl 34 and the teeth 35 may work together to compose a locking
mechanism of the present disclosure. The locking mechanism, the
lock gear 11, and the vehicle sensor 27 cooperate to function as an
emergency locking mechanism. Similar operation and control of the
pawl 34 by the control member and the cam hole 11b is known, and is
not a characterizing portion of the present embodiment, thus the
detailed description thereof will be omitted.
[0066] Shown in FIG. 2, a known torsion bar 36 may extend between
the first and second spool sections 9a, 9b. The right end portion
36a shown in FIG. 2 of the torsion bar 36 may be adapted to rotate
with the first spool section 9a. The left end portion 36b as shown
in FIG. 2 may be adapted to rotate with the second spool section
9b.
[0067] In an emergency situation, the pawl 34 may engage one of the
teeth 35 preventing the second spool section 9b from rotating in
the belt withdrawing direction. Furthermore, the first spool
section 9a may begin to rotate in the belt withdrawing direction
due to the inertia of the occupant against the seat belt. In this
case, the torsion bar 36 may torsionally deform to absorb impact
energy applied to the occupant by the seat belt 4.
[0068] The seat belt retractor 3 of this embodiment may include an
end lock preventive mechanism. The end lock preventive mechanism
may prevent an end lock that may occur due to the actuator 30 of
the vehicle sensor 27 or the fly wheel 12 of the webbing
sensor.
[0069] As shown in FIG. 3 and FIG. 5, the end lock preventive
mechanism 37 for the vehicle sensor 27 may include an end lock
preventive lever 38, an end lock preventive lever position control
spring 39, an eccentric ring 13, and an eccentric gear 14.
[0070] The end lock preventive lever 38 may be rotatably supported
on the casing 10. The end lock preventive lever 38 may include a
locking lever 40 and an unlocking lever 41. The end lock preventive
lever 38 may include a projection 42 and an end lock preventive arm
43. The projection 42 may engage with at least one of first and
second concavities 39a, 39b as curves formed in an end lock
preventive lever position control spring 39, thereby positioning
the end lock preventive lever 38.
[0071] When the projection 42 engages the first concavity 39a as
shown in FIG. 5, the end lock preventive lever 38 may be positioned
and held such that the third lever operation cam 18 may contact the
locking lever 40 and not be allowed to contact the unlocking lever
41. The end lock preventive arm 43 may be set at an end lock
prevention canceling position shown by a solid line in FIG. 5 so as
to set the actuator 30 of the vehicle sensor 27 to an operable
state. When the projection 42 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. 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 such that the end lock preventive arm
43 may contact the actuator 30 so as to lock the actuator 30 at the
inoperable position. Accordingly, the actuator 30 may be set in the
inoperable state.
[0072] According to the embodiment shown in FIG. 3 and FIGS. 6(a),
6(b), the end lock preventive mechanism 44 for the fly wheel 12
includes a pair of stoppers 45, 46, a ring portion 12b of the fly
wheel 12, an eccentric ring 13, an eccentric gear 14, and a cam
groove 49 formed in the casing 10. The lock preventive mechanism 44
also includes a pair of guide grooves 47, 48 that may be spaced
apart from each other in a circumferential direction and by an
angle of 180.degree. so as to oppose each other and extend
linearly.
[0073] The pair of stoppers 45, 46 may be formed in a similar
configuration. Each stopper may include 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, and a cam follower 45c,
46c may move along the cam groove 49.
[0074] The pair of 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 may move in the radial direction of the
eccentric gear 17.
[0075] The cam groove 49 may include a pair of small-diameter
circular grooves 49a, 49b that may include a small circular hole
10a in the casing 10, through which the bush 50 may pass. The pair
of large-diameter circular grooves 49c, 49d may include circular
hole 10a that may be large. The small-diameter circular grooves
49a, 49b and the large-diameter circular grooves 49c, 49d may form
a closed loop. In this case, the pair of small-diameter circular
grooves 49a, 49b and the pair of large-diameter circular grooves
49c, 49d may be alternately arranged in the circumferential
direction of the circular hole 10a. The lengths in the
circumferential direction of the small-diameter circular grooves
49a, 49b may be set to be equal to each other. Similarly, the
lengths in the circumferential direction of the large-diameter
circular grooves 49c, 49d may be set to be equal to each other and
shorter than the lengths in the circumferential direction of the
small-diameter circular grooves 49a, 49b, respectively.
Furthermore, the cam groove 49 of this embodiment may be formed by
an endless-type inner peripheral wall 49e and an endless-type outer
peripheral wall 49f that extends from the side wall of the casing
10 in the axial direction of the spool 9.
[0076] The cam follower 45c of the stopper 45 may be positioned at
one end side within the large-diameter circular groove 49c when the
seat belt 4 is fully wound. In addition, the contact portion 45a
may contact the inner periphery of the ring portion 12b to press
the ring portion 12b in the outer radial direction.
[0077] Similarly, the cam follower 46c of the stopper 46 may be
positioned at one end within the large-diameter circular groove 49d
when the seat belt 4 is fully wound. In addition, the contact
portion 46a may contact the inner periphery of the ring portion 12b
to press the ring portion 12b in the outer radial direction.
[0078] According to an exemplary embodiment, the cam follower 45c
may be positioned within the small-diameter circular groove 49a
when the cam follower 46c is positioned within the small-diameter
circular groove 49b. Conversely, the cam follower 45c may be
positioned within the large-diameter circular groove 49c when the
cam follower 46c is positioned within the large-diameter circular
groove 49d. More particularly, the positions of the cam followers
45c, 46c may be synchronously controlled. Therefore, the contact
portions 45a, 46a of the stoppers 45, 46 may press the inner
periphery of the ring portion 12b 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.
[0079] A known 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, whereby the spring mechanism 51 may
bias the spool 9 in the belt winding direction. By 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.
[0080] Hereafter, respective actions of the ELR-ALR switching
mechanism 25, the end lock preventive mechanism 37, and the end
lock preventive mechanism 44 will be described.
[0081] FIGS. 7(a)-7(d) and FIGS. 8(a)-8(b) show exemplary
embodiments of 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 explaining 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
explaining 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.
[0082] When the seat belt 4 is fully wound, the seat belt retractor
3 may be set by the ELR-ALR switching mechanism 25 in a state where
the seat belt retractor 3 can exercise the ELR mechanism. That is,
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 and may not contact the
disengaging lever 21. Additionally, the second lever operation cam
17 may not contact either the engaging lever 20 or the disengaging
lever 21.
[0083] As shown in FIG. 9(a), the end lock preventive lever 38 of
the end lock preventive mechanism 37 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 not contact the unlocking lever 41 and 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 the end lock
preventing position so that the actuator 30 may be set in the
inoperative state.
[0084] Furthermore, the contact portions 45a, 46a of the 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.
[0085] As the seat belt 4 is withdrawn in this state, the eccentric
gear 14 may rotate at a reduced speed in the belt winding
direction. Shown in FIG. 11(c), the cam followers 45c, 46c of the
stoppers 45, 46 may enter into the respective large-diameter
circular grooves 49c, 49d. Then, 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 lock. In
this case, oscillation may be prevented and the fly wheel 12 may
enter an inoperable state.
[0086] When the seat belt 4 is further withdrawn, the pair of cam
followers 45c, 46c may continue to rotate in the belt winding
direction until they reach the end of the large-diameter circular
grooves 49c, 49d as shown in FIG. 11(d). While the pair of cam
followers 45c, 46c are positioned within the large-diameter
circular grooves 49c, 49d, as shown in FIG. 11(b), the respective
contact portions 45a, 46a continue pressing the ring portion 12b
thereby maintaining the lock of the fly wheel 12.
[0087] As the seat belt 4 is further withdrawn, the cam followers
45c, 46c may further rotate in the belt winding direction
disengaging the large-diameter circular grooves 49c, 49d and
engaging the small-diameter circular grooves 49a, 49b as shown in
FIG. 12(c). Accordingly, as shown in FIG. 12(a), the respective
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.
[0088] The rotational angle of the eccentric gear 14 from when the
seat belt 4 is in the fully wound state to when the pair of cam
followers 45c, 46c enter into the small-diameter circular grooves
49a, 49b is about 60.degree.. Therefore, the amount of the seat
belt 4 withdrawn is small. When the seat belt 4 is withdrawn a
small amount from the fully wound state, the fly wheel 12 may
switch from the inoperable state to the operable state. In the
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 normal, the fly wheel 12 may be
actuated and the engaging claw 12c may engage one of the ratchet
teeth 26. Therefore the lock gear 11 may be prevented from rotating
in the belt withdrawal direction. Since the spool 9 rotates
relative to the lock gear 11 in the belt withdrawal direction, the
pawl 34 may engage one of the internal teeth 35 of the side wall
8b, thereby preventing the second spool section 9b from rotating in
the belt withdrawal direction. As a result, withdrawal of the seat
belt 4 may be prevented.
[0089] When the pair of cam followers 45c, 46c enter into the
small-diameter circular grooves 49a, 49b, the third lever operation
cam 18 may contact the unlocking lever 41 as shown in FIG. 9(b).
Afterwards, 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). Therefore, the end lock preventive lever 38 may be
pivotally moved so that the projection 42 may come off the second
concavity 39b of the end lock preventive lever position control
spring 39 and may engage the first concavity 39a. Thus, 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 may be enter an
operable state. Accordingly, in the event of an emergency, similar
to the conventional vehicle sensor, the actuator 30 may be actuated
by movement of the inertia ball 28 such that the engaging claw 30a
may engage the ratchet teeth 11a of the lock gear 11. When the lock
gear 11 rotates in the belt withdrawing direction due to withdrawal
of the seat belt 4, one of the ratchet teeth 11a may engage the
engaging claw 30a, preventing the lock gear 11 from rotating in the
belt withdrawing direction. Since the spool 9 may rotate relative
to the lock gear 11 in the belt withdrawing direction, the pawl 34
may engage the internal teeth 35 of the side wall 8b, preventing
the second spool section 9b from rotating in the belt withdrawing
direction. FIG. 9(c) shows the actuator 30 in the operative
state.
[0090] When the first spool section 9a rotates in the belt
withdrawing direction due to the inertia of the occupant acting on
the seat belt 4, the torsion bar 36 may torsionally deform similar
to a known torsion bar. The torsional deformation of the torsion
bar 36 may absorb impact energy applied to the occupant by the seat
belt 4.
[0091] As the seat belt 4 is further withdrawn, the third lever
operation cam 18 may pass through the end lock preventive lever 38
as shown in FIG. 12(b). At this point, the end lock preventive
lever 38 may be held at the end lock prevention cancelling position
such that the vehicle sensor 27 may remain in an operable state. As
shown in FIG. 12(d), the pair of cam followers 45c, 46c may further
rotate in the belt winding direction, moving within the
small-diameter circular grooves 49a, 49b. Therefore, as shown in
FIG. 12(b), the contact portion 45a may be held in a state spaced
from the inner periphery of the ring portion 12b, thereby
maintaining the fly wheel 12 in an operable state.
[0092] As the seat belt 4 is further withdrawn, the eccentric gear
14 rotates in the belt winding direction such that the first lever
operation cam 16 moves toward the engaging lever 20 of the
switching lever 19. During this, the vehicle sensor 27 and the fly
wheel 12 may maintain their operable states.
[0093] Immediately before the seat belt 4 is fully withdrawn, as
shown in FIG. 7(b), the first lever operation cam 16 may press the
engaging lever 20. Then, as shown in FIG. 7(c), the switching lever
19 may pivotally move such that the projection 22 of the switching
lever 19 may engage the second concavity 24b of the switching lever
position control spring 24. The switching lever 19 may be
positioned accordingly. That is, the engaging arm 23 may engage the
ratchet teeth 11a of the lock gear 11. Accordingly, the seat belt
retractor 3 may switch from the ELR function mode to the ALR
function mode.
[0094] 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 may engage
the engaging arm 23. In this state, the vehicle sensor 27 may
maintain an operable state as shown in FIG. 9(d). Additionally, 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
large-diameter circular grooves 49d, 49c as shown in FIG. 13(b).
Therefore, the contact portions 45a, 46a may be spaced apart from
the inner periphery of the ring portion 12b as shown in FIG. 13(a).
More particularly, the fly wheel 12 may maintain an operable
state.
[0095] As the spool 9 rotates in the belt winding direction from a
fully withdrawn state, a certain amount of the seat belt 4 may be
wound onto the spool 9. When the spool 9 rotates, 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 may
not engage the ratchet teeth 11a. Therefore, the seat belt 4 may be
smoothly wound onto the spool 9. When the seat belt 4 is withdrawn
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, but one of the ratchet teeth 11a of the lock gear 11 may
immediately engage with the engaging arm 23. Accordingly, the spool
9 and the lock gear 11 may be prevented from rotating in the belt
withdrawing direction, thereby preventing the seat belt 4 from
being withdrawn. In this case, the seat belt retractor 3 may
exercise the ALR function. Due to the rotation of the spool 9 in
the belt winding direction, the eccentric gear 14 may rotate in the
belt withdrawing direction.
[0096] When 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. By further winding of the seat
belt 4, as shown in FIG. 10(a), the third lever operation cam 18
may contact and press the locking lever 40. As shown in FIG. 10(b),
the end lock preventive lever 38 may be pivotally moved 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.
Therefore, the end lock preventive arm 43 may be set and held at
the end lock preventing position such that the actuator 30 of the
vehicle sensor 27 may enter an inoperable state. Since the seat
belt retractor 3 is set in the ALR function mode, the withdrawal of
the seat belt 4 may be prevented in the event of an emergency as
mentioned above.
[0097] Shown in FIG. 8(a), as the seat belt 4 nears being fully
wound the second lever operation cam 17 may contact and press the
disengaging lever 21 of the switching lever 19. Then, 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 of the switching lever 19 may be set 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 switch from the ALR
function mode to the ELR function mode.
[0098] As the seat belt 4 is further wound, as shown in FIG. 11(d),
the cam followers 45c, 46c of the stoppers 45, 46 may enter into
the large-diameter circular grooves 49c, 49d from the
small-diameter circular grooves 49a, 49b, respectively. Therefore,
the contact portions 45a, 46a may contact the inner periphery of
the ring portion 12b and may press the inner periphery of the ring
portion 12b. As a result, the fly wheel 12 is locked and enters an
inoperable state.
[0099] As the seat belt 4 is fully wound, the rotation of the spool
9 and the eccentric gear 14 may be stopped. In this state, the
vehicle sensor 27 and the fly wheel 12 may be locked such that the
vehicle sensor 27 and the fly wheel 12 enter their inoperable
states.
[0100] According to an exemplary embodiment, when the seat belt is
fully or nearly fully wound, the end lock preventive lever 38 may
be controlled by the third lever operation cam 18 of the ELR-ALR
switching mechanism 25. The end lock preventive lever 38 may be set
at the locking position where the engaging claw 30a of the actuator
30 may not engage with any one of the ratchet teeth 11a of the lock
gear 11. Therefore, when the seat belt is fully or nearly fully
wound, an end lock due to the vehicle sensor 27 can be prevented.
Since the end lock preventive lever 38 is not required to rotate
with the eccentric gear 14, the end lock preventive lever 38
requires a reduced operational range. As a result, the end lock
preventive lever 38 may function using a smaller moving space,
allowing for a compact design.
[0101] Since the end lock preventive lever 38 is not required to
pass between the ratchet teeth 11a of the lock gear 11 and the
engaging claw 30a of the vehicle sensor 27, the end lock preventive
lever 38 may be restricted from interfering with the engaging claw
30a. Therefore, the distance between the engaging claw 30a and the
ratchet teeth 11a is not required to be changed similar to a
conventional ELR. Therefore, aforementioned seat belt retractor 3
including an end lock preventive mechanism may be of compact
design.
[0102] Furthermore, the distance between the engaging claw 30a of
the vehicle sensor 27 and the ratchet teeth 11a of the lock gear 11
may be equal to a conventional ELR or ALR without an end lock
preventive mechanism. Accordingly, the moving distance of the
engaging claw 30a between the inoperative position and the
operative position is not required to be changed, allowing the
vehicle sensor 27 to be small. Furthermore, even with the end lock
preventive mechanism 37, a conventional vehicle sensor can be used
as the vehicle sensor 27 of the seat belt retractor 3 of this
embodiment without any change. Therefore, manufacturing of the seat
belt retractor 3 of this embodiment may be inexpensive.
[0103] Since the eccentric gear 14 of the ALR may be used for
controlling the end lock preventive lever 38, an additional
exclusive control member for the end lock preventive lever 38 is
not required. Therefore, the parts count of the ALR can be reduced
even when the end lock preventive mechanism 37 is included.
[0104] Additionally, since the third lever operation cam 18
comprising a simple shape as an end lock preventive member control
cam may be disposed on the eccentric gear 14, the seat belt
retractor can be flexibly and inexpensively adapted to various
layouts of seat belt apparatuses 1 with fewer parts by suitably
setting the position of the third lever operation cam 18 relative
to the eccentric gear 14.
[0105] Furthermore, the end lock preventive mechanism 37 may be
included with the eccentric gear 14. The eccentric gear 14 may
further include a third lever operation cam 18 for switching the
setting position of the end lock preventive lever 38. As a result,
an end lock due to the vehicle sensor 27 can be prevented with the
aforementioned simple structure.
[0106] Furthermore, since the operation of the fly wheel 12 may be
prevented by the end lock preventive mechanism 44, an end lock due
to the fly wheel 12 and/or the vehicle sensor can be prevented.
Therefore, an end lock when the seat belt 4 is fully or nearly
fully wound may be further prevented.
[0107] Additionally, the end lock preventive mechanism 44 may be
included with the pair of stoppers 45, 46. The rotation of the
eccentric gear 14 controls the pair of stoppers 45, 46, thereby
preventing the actuation of the fly wheel 12 when the seat belt 4
is fully or nearly fully wound. Therefore, the actuation of the fly
wheel 12 can be prevented by a simple structure.
[0108] Furthermore, the end lock preventive mechanism 44 may
include the ring portion 12b on the fly wheel 12 and the pair of
stoppers 45, 46 for preventing the actuation of the fly wheel 12.
Therefore, a conventional webbing sensor can be employed without
significant design change. Additionally, the end lock preventive
mechanism 44 may be of simple construction, since the structure
must simply press the ring portion 12b by the stoppers 45, 46.
[0109] According to the seat belt unit 1 of this embodiment, the
seat belt retractor 3 may be employed. Therefore, end locks due to
the vehicle sensor 27 and/or the fly wheel 12 can be effectively
prevented, thereby improving the operability of the seat belt 4 and
providing smooth and stable operation of the seat belt 4 by the
occupant.
[0110] According to an exemplary embodiment the end lock preventive
mechanism 44 for may be provided with a pair of stoppers 45, 46 and
the pair of the guide grooves 47, 48. However, it should be noted
that the present disclosure is not limited to this embodiment. For
example, according to another embodiment two or more stoppers for
pressing the ring portion 12b and two or more guide grooves for
guiding the stoppers may be included. In this case, the respective
stoppers and the respective guide grooves may be formed at any of a
plurality of positions in the circumferential direction of the
eccentric gear 14.
[0111] Additionally, as shown in FIG. 14, the pair of stoppers 45,
46 may be adapted to press in outward radial directions .alpha.,
.beta. of the eccentric gear 14 using an elastic biasing member 53.
Accordingly, the ring portion 12b of the fly wheel 12 can be locked
by greater force. In this case, 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.
[0112] The aforementioned embodiments are illustrative examples for
carrying out the seat belt retractor 3 of the present disclosure.
As such, the respective components of the seat belt retractor 3 may
be varied within the scope of claims of the present disclosure.
[0113] The seat belt retractor and the seat belt unit of the
present disclosure may be suitably used as a seat belt retractor
such that an end lock due to a vehicle sensor and/or a webbing
sensor may occur. The seat belt unit may include at least an
emergency locking function and an automatic locking function.
Additionally, the seat belt unit may employ the seat belt retractor
for restraining an occupant with a seat belt withdrawn from the
seat belt retractor.
[0114] The priority application, Japanese Patent Application No.
2007-229005, filed Sep. 4, 2007 including the specification,
drawings, claims and abstract, is incorporated herein by reference
in its entirety.
[0115] 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.
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