Note: Descriptions are shown in the official language in which they were submitted.
EME~GENCY LOCKING REEL FOR BELTS
This invention relates to emergency locking
reels of the inertia type as used in safety belt
retractor systems and is particularly but not
exclusively concerned with motor vehicle safety belt
retractors. It will be convenient to hereinafter
describe the invention with particular reference to
motor vehicle safety belt retractors, but the invention
has other applications.
Emergency locking reels of the aforementioned
kind are generally complex in construction and must be
manufactured to close tolerances in order to be
satisfactory in operation. Both factors add to the cost
of such reels. A further disadvantage is that, in many
cases, the sensitivity of the automatic reel locking
mechanism is affected by the rotational position of the
reel spindle upon which the belt is wound. Such
variation in sensitivity has adverse consequences on the
operation, and consequently the safety potential, of the
retractor.
Emergency locking reels of the aforementioned
kind are generally constructed so that the locking
action can be triggered in either of two ways. If the
associated vehicle suddenly decelerates, a sensor
device functions to trigger the locking action. If, on
the other hand, the reel spindle is suddenly turned in
the belt unwinding direction - e.g., by a sudden pulling
on the belt - an inertia device functions to trigger the
locking action. The inertia device is usually spring
influenced into a rest position at which its
relationship with other parts of the mechanism is such
that it does not function to prevent rotation of the
reel spindle. The influence of the spring, however, is
affected according to the rotational position of the
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reel spindle and that variation in spring loading
causes a variation in the sensitivi-ty of the inertia
device to the conditions which trigyer the reel loc~ing
action.
It is an object of an aspect of the present
invention to provide an emergency locking reel of the
aforementioned kind in which the sensitivity of the
inertia device is substantially unaffected by the
rotational position of the reel spindle.
It is an object o~ an aspect of the invention
to provide an emergency locking reel in which major
components are arranged symmetrical about a plane
containing the spindle axis so that the reel can be
easily adapted for use with either hand of rotation for
belt unwinding.
It is an object of an aspect of the invention
to provide an emergency locking reel in which the sensor
which responds to vehicle deceleration can be easily
secured in any one of a variety of positions selected
according to the disposition of the reel when attached
to a vehicle.
It is an object of an aspect of the invention
to provide an emergency locking reel of simplified
construction and in which critical parts are located in
correct relative positions with minimum demand on
manufacturing tolerances. That is, the general assembly
is rationalized in such a way as to simplify manufacture
and thereby reduce costs.
It is an object of an aspect of the invention
to provide an emergency locking reel having simplified
and secure means for fastening an end of the belt to the
rotatable spool on which it is wound.
According to one aspect of the present
invention, there is provided an emergency locking reel
for a safety belt locking means operable to prevent
rotation of said spindle relative to said frame in one
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direction, a ratchet wheel connected to said spindle
for rotation therewith, means operable to temporarily
halt rotation of said ratchet wheel in said one
direction w.ith the spindle, said ratchet wheel and
spindle connection including a tension portion of a one-
piece helical coil spring, said tension portion
operating to normally retain said ratchet wheel and
spindle in a particular rotational relationship and
being stretchable to allow relative rotation of said
ratchet wheel and spindle, said locking means being
arranged to operate in response to said relative
rotation, an inertia plate mounted on said spindle for
limited rotation relative thereto, a detent carried by
said ratchet wheel for rotation therewith and being
responsive to a change in the relative rotational
positions of said ratchet wheel and said inertia plate
so as to operate to stop rotation of said ratchet wheel,
and a compression portion of said spring acting between
said ratchet wheel and said inertia plate to resist said change
and which is compressed in response to such change so as to be
biased to restore sai.d ratchet wheel and inertia plate to the
relative rota-tional positions thereof which existed prior to
said change.
In an emergency locking reel as described above, the
inertia plate has the capacity to move relative to all other
eomponents, or at least those components which are critical to
the reel locking funetion. In particular, the inerti.a plate
is preferably formed separate from the ratchet wheel which is
usually assoeiated with the sensor device in such reels, whereas
in pri.or constructions it was not uncommon for the ratchet wheel
to inelude or eomprise the inertia member. It is a further
feature of the invention that the inertia plate and ratchet
wheel are spring biased into a particular relationship in such
a way that the spring force acting between the two components
is substantially unaffected by the rotational position of the
reel spindle.
According to a further aspect of the invention, there is
provided an emergeney locking reel for a safety belt including,
a frame, a spindle rotatably mounted on said frame, a rotatable
ratehet wheel, a one-piece helical coil spring having a tension
portion whieh eonneets said ratehet wheel to the spindle so that
the ratehet wheel rotates with the spindle but is able to
rotate relative to said spindle as a eonsequenee of stretehing
of said tension portion, locking means which is operable in
response to said relative rotation to prevent rotation of said
spindle relative to said frame in one direction, an inertia
deviee and a deeeleration sensor deviee, each of which is
operable to eause operation of sai.d relative rotati.on of the
ratehet wheel and the spindle, said deeeleration sensor device
ineluding means wheh is operable to stop rotation of sai.d
ratchet wheel with said spindle, said inertia device inc L uding
an inertia plate whieh is mounted on said spindle for limited
rotation relative thereto, a detent responsive to a change in
the relative ro-tational positions of said ratchet wheel and
said inertia plate so as to operate to cause said ratchet wheel
to be held against rotation with said spindle, and said spring
has a eompression portion which acts between sai.d ratehet wheel
and said inertia pla-te to resi.st that change and is compressed
in response to such change to apply a res-toring force whereby
said ratchet wheel and inertia plate are returned to the
relative rotational positions which existed prior to said
change, the arrangement being such that said spring compression
portion is compressed as a consequence of sudden rotation
of said spindle in said one direction to thereby cause said
change in relative posi-tions so that said detent becomes
operative, said spring tension portion thereafter stretches
as a consequence of rotation of said spindle relative to said
ratchet wheel, and said locking means is thereby rendered
operative to prevent further rotation of the spindle in said
one direction.
An embodiment of the invention is described in detail in
the following passages of the specification which refer to -the
accompanying drawings. The drawings, however, are merely
illustrative of how the invention might be put into effect,
so that the specific form and arrangement of the features shown
is not to be understood as limiting on the inven-tion.
In the drawings:
Figure 1 is a partially sectioned end elevational view
of one form of reel assembly incorporating an embodiment of
the invention;
Figure 2 is a cross-sectional view taken along line II-II
of Figure l;
Figure 3 is a cross-sectional view taken along line
III-III of Figure 2;
Figure 4 is a cross-sectional view taken along line IV-IV
of Figure l;
Figure 5 is a cross-sectional view taken along line V-V
of Figure 2;
Figure 6 is an exploded view of some of the components
of the mechanism shown in Figures 1 and 2;
Figure 7 is a cross-sectional view taken along line
VII-VII of Figure 2 and showing the relative posi.tions of
various components of the mechanism when related components
as shown in Figure 5 have the relative positi.ons shown in
Figure 5;
Figure 8 is a view similar to Figure 5 but showing the
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components arranged to initiate the reel locking action;
Figure 9 is a view similar to Figure 7 but showing the
condition corresponding -to that shown in Figure 8;
Figure 10 is a view similar -to Figure 8 but showing the
spindle of the reel advanced beyond the position shown in
Figure 8;
Figure 11 is a view similar to Fiyure 9 but showing the
posi-tion adopted under the condition exi.sting i.n Figure 10;
Figure 12 is a cross-sectional view taken along line
XII-XII of Figure l;
Figure 13 is a view of the vehicle deceleration sensor
shown in Figure 1, but showing the sensor activated to initiate
the reel locking action;
Figure 14 is a cross-sectional view taken along line
XV-XV of Figure 2;
Figure 15 is an exploded view of the components shown
in Figure 14, but showing the spool in transverse cross-section;
Figure 16 is an end view of the reel assembly taken from
the end opposite to that shown in Figure l;
Figure 17 is a view taken along line XVII-XVII of Figure
16;
Figure 18 is a cross-sectional view taken along line
XVIII-XVIII of Fi.gure 17;
Figure 19 is a view taken along line XIX-XIX of Figure 16;
Figure 20 is a cross-sectional view taken along line
XX-XX of Figure 16; and,
Figure 21 is a cross-sectional view taken along line
XXI-XXI of Figure 19.
A typical reel assembly to which the invention is
applicable is shown in Figures l and 2, and includes a metal
frame 1 which is securable to a vehicle in an appropriate
position and has end walls 2 which provide a mounting for a
rotatable spool 3. A section of webbi.ng strap (not shown),
which in use forms part of the safety belt, is wound upon the
spool 3 and the spool 3 is urged in a belt winding directi.on by
a suitable return spring 4. Reel locking mechanism is provided
at one end of the assembly and a housing 5 moulded from
plastics or other suitable materi.al is arranged to enclose tha-t
mechanism. A further housing part 6 is arranged to enclose the
return spring 4, whi.ch i._ ~ tne end of the frame 1 opposite
to that at which the aforementi.oned mechani.sm i.s located.
In the preferred construction shown, the spool 3 includes
a spindle 8 which is a composi.te struc-ture having a metal core
9 and a body 10 of plastics or other mouldable material (figure
14). In the example shown, -the core g comprises -two flat
strips 11 secured i.n face-to-face engagement, whereas the
spindle body 10 is a cylindrical section moulded about that
core 9. An end porti.on 12 (figure 2) of the core 9 protrudes
beyond one end of the spindle body 10 for a reason hereinafter
made clear. It will be appreciated that the core 9 could be
made from a single strip of metal rather than two strips as
described and it could be a bar or rod rather than a strip.
Each end wall 2 of the frame 1 has an opening 13 through
which the spindle 8 projects and provides the basis of a
rotatable mounting for the spindle 8. Preferably, as shown,
the rotatable mounting at each end wall 2 includes a bearing
collar 14 of plastics material, for example, disposed within
the respective end wall opening 13 and which rotatably receives
a respective cylindrical portion 15 and 16 of the spindle body
10. In the constructions shown, each such bearing collar forms
an integral part of a respective end plate 17 and 18 of the
assembly. Each end plate 17 and 18 may be moulded from
plastics material and preferably lies in face-to face engagement
with the outside surface of the respective frame end wall 2 as
shown.
According to the arrangemen-t shown, the reel locking
mechanism is provided on the outside of one frame end wall 2
and the spindle return spring 4 is provided at the outside of
the other end wall 2. The reel locking mechanism of that
particular arrangement includes an internally toothed locking
ring 19 which is secured to the frame 1 against relati.ve
movement, and a locking pawl 20 (figure 7) which is rotatable
with the spindle 8 and is movable radially of the spindle 8
to adopt either an outer lock position (figure 11) or an inner
release position (figure 7). In the outer position, a toothed
part 21 of the locking pawl 20 engages with the locki.ng ring
teeth 22, and in the inner posi.tion tha-t toothed part 21 is
located clear of the locking ring teeth 22 so that the pawl 20
can rotate freely wi.thin the space surrounded by the locking
ring 19. Spring means as hereinafter descri.bed normally urges
the pawl 20 into the inner positi.on.
It is generally convenient to form -the locking ring 19
from a metal. plate having a ci.rcular opening which is arranged
coaxial with the spindle 8 when the ring 19 is secured in
place. For example, the ring 19 may be secured by cli.nching
as shown at 23 in figure 2 so that the ring 19 is secured
direct to the adjacent end wall 2, although outside the actual
points of connection the moulded end plate 17 in-tervenes between
the ring 19 and the end wall 2. The teeth 22 are formed around
the periphery of the ring opening and it is preferred that each
tooth 22 is symmetrical about a plane which passes through the
axis of the spindle 8. By way of illustration, such a plane is
represented by the line 24 in figure 1 and point 25 represents
the spindle axis.
The plane 24 therefore bisects its respective tooth 22,
and if the ring 19 has an even number of teeth 22 the plane 24
will be common to two teeth 22 located on respective opposite
sides of the spindle axis 25~ Each tooth 22 then has two
sloping side faces 26 and 27 which converge towards the axis
25 and slope at substantially the same angle relative to the
respective plane 24. A ring 19 having such teeth 22 is
therefore adapted for use in the reel assembly shown regardless
of which direction of rotation of the spool 3 is the unwinding
direction. In the figure 7 arrangement, the spool 3 unwinds
in the anti-clockwise direction and the pawl teeth 21 react
with side faces 26 of the teeth 22 to halt that rotation. If
the unwinding direction was clockwise, the pawl 20 would be
inverted and it would react with faces 27 of the teeth 22.
Adaptability of the locking ring 19 to ei.ther hand of
operation presents a significant saving in the cost of
manufacturing reel assemblies.
The pawl 20 is located within -the opening of the ring 19
as best seen in figure 2. Thus, both the pawl 20 and the lock-
ing ring 19 are separated from the outside surface of the
adjacent frame end wall 2 only by the intervenlng end plate 17
so that forces resulting from engagement of the pawl 20 and
ring 19 are substantially reacted into the frame 1. The body
part 10 of the spindle 8 preferably does not ex-tend substantially
beyond the outermost surface of the end plate 17, but as
previously mentioned an end portion 12 of the core 9 projects
beyond the body part 10 a-t that end of the spindle 8. The pawl
20 may be a plate-like member, formed of metal, for example,
having an opening 28 through which the core end portion 12
projects (figure 2). The opening 28 is shaped to allow li.mited
relative rotation between the pawl 20 and spindle 8 as
hereinafter described.
In the preferred construction shown, the pawl 20 is
activated to adopt its outer lock position either by operation
of an inertia device or by operation of a deceleration sensor
device. In the construction shown, both devices influence the
pawl 20 through the intermediary of a ratchet wheel 29 which
is connected to the spindle 8 to rotate therewith and is also
connected to the pawl 20 through a suitable coupling 30
(figures 6 to 11) which functions as hereinafter described.
The wheel 29 is mounted on the exposed end portion 12 of the
spindle core 9 at a location di.rectly adjacent to the pawl 20
as best seen i.n figure 2.
The ratchet wheel 29 may be generally in the form of a
circular disc having a series of ratchet teeth 31 formed about
its outer periphery (figure 6). The wheel 29 i.s drivably
connected to the spindle 8 in any appropriate fashion, but that
connection is preferably such that it includes a lost motion
facility whereby the wheel 29 and spindle 8 are capable of
limited relative rotation.
In the form of dri.ve connection shown, the wheel 29 is
rotatably mounted on a cylindrical portion 32 (figure 2) of an
end cap 33 which is non-rotatably attached to the spindle core
end portion 12 as hereinafter described. Rotation of the wheel
29 relative to the spindle 8 is limited by interaction between
the wheel 29 and the pawl 20 and the aforementioned lost motion
facility is provided by the connection between the pawl 20 and
spindle 8. That is, the wheel 29 is coupled at 30 to the pawl
20 against relative rotation, but the pawl 20 is adapted for
limited rotation relative to the spindle 8 and it is that
adaptability which provides the lost motion facili.ty for the
ratchet wheel 29.
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The drive connection be-tween -the ratchet wheel 29 and
spindle 8 also includes resi.lient means which urges the wheel
29 in one direction of rotati.on relative to -the spindle 8,
which is the unwinding di.recti.on of the spool 3. In the
construction shown, that resilient means i.ncludes a spring 34
of helical coil 4 having an inner end portion 35 secured to
the end cap 33 and an outer end portion 36 acting agai.nst the
ratchet wheel 29 at a location spaced radially outwards of the
spindle axi.s 25 (figure 5). The two end portions 35 and 36
are preferably enlarged to assist retention of the spring 34
as hereinafter discussed and an intermediate portion 74 of the
spring 34 is turned around an edge 68 of a plate-like section
69 which is integral with and stands out from the ratchet wheel
29. The arrangement is such that the in~ermedi.ate portion 74
acts as a tension spring and allows some degree of relative
rotation between the spindle 8 and ratchet wheel 29 for a
purpose hereinafter made clear. Under normal conditions,
however, the spring portion 74 transmits drive from the spindle
8 to the ratchet wheel 29 when the spindle 8 is rotating in
the belt unwinding direction.
As best seen in figures 7, 9 and 11, the part of the
spindle end portion 12 which locates in the pawl opening 28
is generally rectangular i.n cross-section, although other
non-circular shapes may be adopted. The opening 28 is shaped
relative to the shape of the end portion 12 so that the spindle
8 is able to rotate to a limited extent relative to the pawl
20. In the particular arrangement shown, the opening 28 has
one edge (hereinafter called the back edge) which is shaped to
provide two spaced humps 37 and 38, each of whi.ch i.s engageable
with a broad surface 39 of the spindle core 9 adjacent
respecti.ve longi-tudinal edges 40 and 41 of that core 9. The
opposite or front edge of the opening 28 has a recess 42
extending over a substantial part of i-ts length and the non-
recessed part 43 is spaced from the adjacen-t broad surface 44
of the spindle core 9 when the back edge humps 37 and 38
engage that core 9. Another two opposed edges 45 and 46 of
the opening 28 lie relatively close to respective longitudinal
edges 40 and 41 of the spindle core 9 so that the spindle core
9 is substantially confined at those longitudinal edges.
The coupliny 30 between the ratchet wheel 29 and the
pawl 20 is located radially outwards of the spi.ndle axis 25
and cooperates wi.th the spindle core g i.n holdiny the pawl 20
against rotation about that axi.s relati.ve to the ratchet wheel
29. The coupling 30 does, however, allow some relative
movement between those two components as hereinaf-ter described.
In the form shown, the coupling 30 comprises a pin 47 extending
laterally from one si.de surface of the ratchet wheel 29 and
which is slidably located within a radi.al slot 48 formed
through the peripheral edge of the pawl 20. The arrangement
is such that the pawl 20 is able to move radially relative to
the ratchet wheel 29 over a limited distance (see figures 7
and 11).
When the spool 3 is in a static conditi.on, the pawl 20
is at its inner release position (figure 7) at which the back
edge humps 37 and 38 engage against the adjacent broad surface
39 of the spindle core 9. If the spindle 8 is turned in the
unwindi.ng direction, rotation is transferred from the ratchet
wheel 29 to the pawl 20 through the coupling 30 and although
the back edge of the pawl opening 28 is the -trailing side it
nevertheless remains against the spindle core 9 because of the
influence of the spring 34. Should rotation of the ratchet
wheel 29 be prevented such as by operation of the sensor device,
the pawl 20 will also stop turning, but the spindle 8 will
continue turning in the unwinding directi.on because of the pull
maintained on the belt strap. The spindle 8 will therefore
turn against the influence of the spring 34 so as to axially
extend or stretch the portion 74 of that spring 34 (figure 10).
In that regard, the spring end portion 35 is captured between
two lugs 129 of the cap 33 and is thereby held against
movement relative to the cap 33.
Such relative movement between the spindle 8 and the
pawl 20 and ratchet wheel 29 is permitted by the flexibi.lity
of the connection provided by the spring 34. That i.s, the
spring portion 74 stretches to allow for over-travel of the
spindle 8 in the unwinding di.rection. As that over-travel
commences, the spindle core 9 leaves engagement with the back
edge hump 38 of the pawl opening 28, which is the hump opposite
to the front edge recess 42. On the other side of the spindle
axis 25, however, the core 9 presses ayainst -the back edge hump
37 and thereby pushes the pawl 20 radially to cause it to adopt
its outer positi.on at which it engages with -the locking ri.ng 19
to prevent further unwinding rotati.on of the spindle 8 (figure
1 1 ) .
When the unwinding turning force is removed from the
spindle 8, it will be driven in the winding di.rection by the
return spring 4. At the commencement of such rewi.nding, the
spindle core 9, ratchet wheel 29 and pawl 20 will return to
their ori.ginal relative posi.tions because of the influence of
the stressed spring 34 on the ratchet wheel 29.
A sensor device for the assembly so far described may
operate on the floating ball principle, which is well known i.n
itself. Such a device 49 is shown in figures 2 and 13 and
includes a metal sphere or ball 50 located in a cup 51 having
a contoured base 52 such that the ball 50 normally seeks to
adopt a rest position on that base 52 at which it has its
lowermost position in the cup 51 (figure 2). The cup 51 may
be attached to or formed as an integral part of the assembly
housing. In the preferred construc-tion shown, however, the cup
51 is separately formed and has a part spherical outside surface
53 which is engageable with a substantially complementary
surface of the housing or a member secured thereto. That
arrangement permits the cup 51 to be mounted on the housing
with its open mouth 54 uppermost, regardless of the disposition
of the reel assembly relative to the vehicle in which it is
installed.
In the construction particularly shown, the sensor cup 51
is located between the housing end plate 17 and an end cover
55 of the housing. Spherical cavi-ties 56 and 57 provided in
the end plate 17 and cover 55 respectively are substantially
complementary to the spherical surface 53 of the cup 51 and
are generated about a common centre. The cup 51 is therefore
able to be located neatly within the space confined by the
cavities 56 and 57 and positioned so that the open mouth 54
has any desired disposition. When a particular relative
position has been selected for the cup 51, it can be fixed to
either the end plate 17 or the cover 55 by induction weldi.ng or
other appropriate means. One possible alternative is to projec-t
a pin (not shown) of plastics material through the relevan~
housing part and secure i.t to that part and the cup 51 by spin
welding. In that regard, the end plate 17, cover 55 and cup
51 can each be moulded or otherwi.se formed from a plastics
material.
~ hen the vehicle suddenly decelerates, the ball 50 moves
out of its rest position due to its relatively high inertia
and as a consequence is li.fted by the contoured base 52 of
the cup 51 (figure 13). That lifting movement is used to
initiate the reel locking action and ln the arrangement shown
that is effected through a lever 58 pivotally moun-ted on the
housing and arranged to respond to the ball movement - e.g.,
through direct engagement with the ball 50. A terminal end
portion 59 of the lever 58 is located close to the periphery
of the ratchet wheel 29 so as to be movable into engagement
with the ratchet teeth 31 and thereby stop rotation of the wheel
29 when the sensor ball 50 lifts. In that regard, the ball
50 engages with the lever 58 at a location between its pivoted
end 60 and the end portion 59.
As shown in figure 13, the lever 58 i.s arranged to halt
rotation of the ratchet wheel 29 i.n the anti-clockwise
direction, whi.ch is the reel unwinding di.recti.on for the
assembly shown. If the spindle 8 is turning in the unwinding
direction at that time, the condition shown in figure 13 wi.ll
cause the pawl 20 to be held against rotation so the spindle
8 will rotate relative to the pawl 20 and thereby push the
pawl 20 into the reel locking position as shown in figure 11.
In the particular construction shown, the lever 58
projects between two spaced bars 61, which act as guldes for
the lever 58 during its movement between the figure 1 and
figure 13 positions. The bar 61 closest to the lever pivot 60
also functions as a support for the lever 58 when i.t i.s pushed
back by its engagement with the ratchet teeth 31. That i.s, the
end portion 59 of the lever 58 is adapted to be pushed back
against an abrupt face of the aforemen-tioned bar 61. Such an
arrangement provides support for the lever 58 adjacent to where
it engages the ratchet wheel 29 and therefore enables the lever
58 to be made of a relatively light construction. The
sensitivity of the mechanism is thereby improved.
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In the construction shown, there i.s a plurality of bars
61 arranged in a ci.rcular arc which is concentric with the
spindle axis 25. As best seen in fiyure 1, each bar 61
extends across the valley between a respective pair of locking
ring teeth 22 and is wedged between opposed si.de surfaces of
those teeth 22. Furthermore, each bar 61 projec-ts beyond the
outer side surface 67 of the locking ring 19 so as to be
exposed for guiding engagement with the lever 58. The bars
61 therefore provide a series of stationary guides which are
supported by the locking ring 19 and are engageable by the
lever 58.
Preferably, the bars 61 are formed integral wi.th the end
plate 17 as shown in figure 6. The bars 61 may function as
locating means for the locking ring 19 and thereby provide a
convenient means for achieivng accurate assembly of the end
plate 17 and ring 19. That is, the concen-tricity of the circle
of bars 61 with the spindle 8 is fixed during moulding of the
end plate 17 because the spindle bearing 14 is also an integral
part of the plate 17. The bars 61 in turn fix the ring 19 in
concentric relationship with the spindle 8.
A feature of the particular construction shown is that
the housing parts 17, 18 and 55 are substantially symmetrical
about a plane which contains the spindle axis 25. The end cover
62 which encloses the return spring 4 may also be symmetrical
about the same plane, which i.s represented by line 63 in
figure 1. With regard to the housing parts 17 and 55, they
are preferably arranged so that the centre about which each
spherical cavity 56 and 57 is generated, lies substantially in
the plane 63. That is, the portion of the housing which
retains the sensor 49 is also symmetrical about the plane 63.
As shown in figure 1, it is also preferred that the plane 63
passes substantially through the centre of the sensor ball 50
when that ball i.s in its rest position as also shown in figure 1.
Such a symmetrical arrangement has the advantage that the
housing parts 17, 1~, 55 and 62 can be used regardless of the
hand of operation (i.e., directi.on of unwinding rotation) of
the reel. For that purpose, the housing parts 17 and 55
preferably have two separate mountings 75 for the sensor lever
pivot 60, and a respecti.ve one of those mounti.ngs 75 i.s
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selecled for use according to the hand of operation of the reel.
The frame 1 is also usable with either hand of operation.
Manufacturing costs are thereby minimised.
An inertia device for the assembly described includes a
member separate from both the pawl 20 and the ratchet wheel 29,
and that member is preferably in the form of a disc-like plate
64 (figures 2, 5, 6 and 8) formed of metal or other suitable
material. The inertia plate 64 may be rotatably mounted on a
boss portion 65 of -the ratchet wheel 29 which projects axially
from that side of the wheel 29 remote from the pawl 20 (see
figu~e 2). A detent 66 is associated with the inertia plate
64 so as to be responsive to changes in the relative positions
of the inertia plate 64 and ratchet wheel 29 to adopt either an
operative position (figure 8) or an inoperative position
(figure 5). In the operative position, the detent 66 engages
a tooth 127 (figure 6) of a series of teeth which are formed
integral with the cover 55 and are arranged in a circle
coaxial with the spindle 8. Rotation of the ratchet wheel 29
in the belt unwinding direction is halted as a result of that
engagement and there is consequent actuation of the pawl 20
as previously described. In the inoperative position, the
detent 66 is held clear of the teeth 127.
According to the particular construction shown, the
detent 66 is a levex having one end 70 pivotally mounted on
the pin 71 projecting laterally from the side of the ratchet
wheel 29 adjacent to the inertia plate 64. The pivot pin 71
is located relatively close to the periphery of the ratchet
wheel 29 so that the detent 66 can swing outwardly to bring
its terminal end 72 into engagement with one of the teeth 127.
Also in the construction shown, the detent 66 is located within
a pocket 73 formed through the sides and periphery of the
inertia plate 64 (figure 6) and which is so shaped as to
influence pivotal movement of the detent 66 according to the
relative rotational positions of -the ratchet wheel 29 and
inertia plate 64.
The ratchet wheel 29 is preferably arranged, as shown,
to drive the inertia plate 64 in the unwinding direction through
the interaction of the spring outer end portion 36 which holds
those two components in a normal relationship (figure 5), but
L6
allows relati.ve over-travel of the ratchet wheel 29 i.n the
unwinding directi.on under ci.rcumstances discussed below (fiyure
8). In the normal rotati.onal relationship as shown in figure
5, an edge 76 of the i.nertia pla-te pocket 73 bears against an
adjacent edge 77 of the detent 66 so as to urge that detent 66
abou-t its pivot 71 into -the inopera-tive posi.tion. Should the
ratchet wheel 29 over-travel in the unwinding direction,
however, the detent 66 i.s carried with it so as to clear the
pocket edge 76 and then coacts with part of the i.nerti.a plate
64 so as to be caused to pivot outwardly for engagement with
the bars 61.
In the form shown, the aforementioned coaction occurs
through a fulcrum lobe 78 projecting from a peripheral edge
of the inerti.a plate pocket 73 and which locates within a
substantially complementary recess 79 in the adjacent edge of
the detent 66. That lobe 78 is located radially outwards of
and adjacent to the pivot pin 71. Obviously, other arrangements
could be adopted to achieve the same function.
The inertia plate 64 is preferably made of metal and is
relatively heavy by comparison with the ratchet wheel 29.
Thus, if the spindle 8 is moved suddenly in the unwinding
direction, the greater inertia of the inertia plate 64 will
cause it to lag behind the movement of the ratchet wheel 29.
The interacting spring portion 36 is stressed to allow that to
occur. As a result, the detent 66 is swung outwardly as
described above to engage one of the teeth 127 and thereby
bring the ratchet wheel 29 to a halt. Thus, the pawl 20 is
actuated as also described above, and the pawl 20 then functions
to lock the spindle 8 against further unwinding rotation.
It is preferred, as shown, that the spring portion 36
which acts between the ratchet wheel 29 and inertia plate 64
acts as a compression spring located and is adjacent the outer
periphery of both the wheel 29 and plate 64. In -the
construction shown, the spring portion 36 is formed integral
with the remainder of the spring 34 and has its axis extendi.ng
generally in the circumferential direction of the ratche-t wheel
29. The spring portion 36 is arranged endwise between an
abutment 80 of the ratchet wheel 29 and an opposed surface 81
of the inertia plate 64 so as to be subjected to compressi.on
in the event that the ratchet wheel 29 over-travels in the
unwinding direction. The abutment 80 is formed by a step on
the section 69 of the wheel 29 and a simi.lar step on another
and spaced plate-like section 128 of the wheel 29. The
arrangement is such that the outer end por-tion 36 of the spring
34 is secured to the ra-tchet wheel 29 agai.nst relative
movement so that rotation of the spindle 8 can be transferred
directly to -the ratchet wheel 29.
In the arrangement shown, an end of the spri.ng portion
36 engages over a peg 123 which projects from the inertia
plate surface 81. The spring portion 36 and the sections 69
and 128 which carry the abutment 80 are located within a
recess 124 (figure 6) formed in the periphery of the inertia
plate 64 and the surface 81 forms one extremity of that recess
124. When the inertia plate 64 and the ratchet wheel 29 are
in their normal relative positions as shown in figure 5, it
is preferred that at least one of th.e sections 69 and 128
engages the other extreme end surface 125 of the recess 124
and that proper engagement is maintained between the surfaces
76 and 77 of the inertia plate 64 and detent 66 respectively.
In that position, inward travel of the detent 66 about its
pivot 71 is limited by engagement with a peripheral surface 126
of the inertia plate 64.
When the spindle 8 is turned without sudden movement i.n
the unwinding direction, rotational movement of that spindle
8 is transferred to the ratchet wheel 29 through the spring
portion 74. The wheel 29 in turn transfers the movement to
the inertia plate 64 through the spring portion 36. Because
of the relatively gentle nature of the turning force, the
spri.ng portion 36 will remain in its normal (uncompressed) state
as shown in figure 5 and consequently the interacti.on between
the inertia plate 64 and detent 66 will retain that de-tent 66
in its inoperative position (figure 5). The pawl 20 is also
influenced to turn in the required direction through its
connection with the ratchet wheel 29 and because of that
connection the spring 34 also influences the pawl 20 into
its inner release position (figure 1).
If the spindle 8 is suddenly turned in the unwinding
direction, the spring portion 74 will pull the ratchet wheel
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29 in the requi.red directi.on, but because the inerti.a plate
64 has greater resistance -to the turni.ng force it will react
against the compressible spring portion 36 causing momen-tary
collapse of that spri.ng porti.on (figure 8). The ratchet wheel
29 over-travels as a resul-t of that collapse and -the detent
66 becomes operative in the manner previ.ously described
(figure 8). Thus, the ratchet wheel 29 is brought to a hal-t,
but the spindle 8 continues to turn in the unwinding di.rection
thereby causing operation of the pawl 20 as also previously
described (figure 11). That over-travel of the spindle 8
stresses the spring portion 74 so that it applies a returning
force to the ratchet wheel 29 (figure 10).
Thus, when the unwinding force is removed, the spindle
8 is urged in the rewinding direction by the return spring 4,
but at the same time the spring 34 functions to return the
ratchet wheel 29 to its original rest position relative to
the spindle 8. As a result, the ratchet wheel 29 carries the
pawl 20 with it so that both over-travel the spindle 8 in
the rewinding direction and the pawl 20 is caused to adopt its
inner release position as previously described. It therefore
follows that the spring 34 indirectly provides a blas whereby
the pawl 20 is urged i.nto its inner release position.
A biasing spring 34 as described above therefore has the
advantage of simplicity and the further advantage of maintain-
ing a substantial constant bias on the pawl 20 regardless of
the rotational position of that pawl 20. In that regard, the
spring 34 does not act directly on the pawl 20, but acts on
that pawl 20 through the intermedi.ary of the ratchet wheel 29.
Furthermore, the coaction between the pawl 20 and the ratchet
wheel 29 at the coupling 30 is such that, under normal
operating conditions, the pawl 20 does not impose a turni.ng
moment on the ratchet wheel 29 such as to act against the
spring bias and consequently the magnitude of that bias is not
affected by changes in the rotati.onal position of the pawl 20.
A further significant feature of the construction
particularly described is that there is a minimum of metal
components and strength is imparted where necessary by rather
simple means. Also, the use of a single moulding to provide
the spindle bearing 14, locking ring locating bars 61 and sensor
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locating cavity 56 is advantageous. With that arrangement the
bearing 14 and ring 19 are made coaxial so their cri-ti.cal
relationship does not depend upon accurate manufacture of
other components. As the same moulding provides at leas-t part
of the spheri.cal seat for the sensor cup 51, it automatically
establishes a correc-t relationship between the sensor device
and other componen-ts of the mechanism~ Still further, that
single moulding assists in providing an effective environmental
seal for the assembly, and if desired may be attached to the
adjacent frame end wall 2 by snap engagement.
As a further aid to simplifying manufacture, the end cap
33 which provides the rotational mounting for the ratchet wheel
>9, may be connected to the assembly by snap engagement. Two
laterally spaced legs 82 of the cap 33 may extend axially on
respective opposite sides of the spindle core 9 as shown in
figure 3, and extend into a cavity 83 at the adjacent end of
the spindle body 10. A detent 84 on the terminal end of each
leg 82 snap engages behind a surface 85 of the spindle body 10
which is provided within the cavity 83 and thereby retains the
spindle 8 and end cap 33 in assembly. A flange 86 at the outer
end of the cap 33 may overlie part of the inertia plate 64 to
retain that plate 64 in assembly and thereby also retain the
ratchet wheel 29 and pawl 20 in assembly. The flange 86 may
be extended in one lateral direction as shown to overlie the
pivoted end portion 70 of the detent 66 and consequently
function to also retain the deten-t 66 on the pivot pin 71.
Assembly may be further simplified by providing laterally
extending lugs 81 on the spindle core 9 to overlie the outer
end face 88 of the pawl 20 and thereby re-tain the pawl 20 in
correct axial position (figure 1). Windows 89 formed through
the ratchet wheel 29 provide a clearance space for the lugs 87.
Lugs 90 on the end cap 33 may locate behind the ratchet wheel
29 to assist in fixing its axial position (figure 3).
The belt strap is preferably secured to the spindle 8
in the manner shown in figure 14 which does not require a loop
to be formed on the strap end by stitching. In that preferred
arrangement, an axially extending slot 91 is formed through
opposite sides of the spool 3 to allow passage of -the strap 92.
The open mouth 93 of the slot 91 is enlarged at one side of
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the spool 3 as shown, and opposed surfaces 94 of that enlarged
mouth 93 diverge outwardly, preferably from a location spaced
from the spindle axis 25. The strap 92 is passed through the
slot 91 from the side remote from the enlarged mouth 93 and
a strap retainer 95 is attached to the terminal end portion 96
of the strap 92 and whi.ch cooperates with the diverging
surfaces 94 to firmly retain the strap 92 against wi.thdrawal
from the spool 3.
In the particular constructi.on shown, the retainer 95
is of bar-like form having two longitudinal jaw sections 97
arranged in face-to-face relationship and separa-ted by a groove
98 extending the full length of the retainer 95. Oppositely
facing outer surfaces 99 of the body of the retainer 95 diverge
away from the front longitudinal edge 100 of the retainer 95
so that a portion of the retai.ner 95 has a transverse cross-
sectional configuration which is substantially complementary
to that of the enlarged slot mouth 93. The base of the groove
98 may be enlarged as shown at 101 in figure 14 to accept the
terminal end 102 of the strap 92.
In use, the end portion 96 of the strap 92 is located
between the jaw sections 97 and the immediately adjacent strap
portion 103 is then turned back over the front edge 100 of
the retainer 95 and from there is arranged to overlie the outer
surfaces 99 and the back edge 104 of the retainer 95. That is,
the strap portion 103 effectively encapsulates the retainer 95
and one part 130 of the strap 92 is clamped between part of
the strap portion 103 and a plate-like section 131 of the
retainer 95. The strap 92 then extends beyond the front edges
100 of the retainer 95 into the slot 91 and emerges through
the opposite mouth 105 of the slot 91. Retention of the strap
92 is effected by locating the strap end 102 in the groove
enlargement 101, clamping the strap part 130 against the
retainer 95 and clamping the strap portion 103 against the
sloping surfaces of the spool 3.
A spool body, which forms a strap guide, is attached to
the outside of the spindle 8 to retain the wound strap in a
neat coil. That may comprise a sleeve 106 having a laterally
extending flange 107 at each end and having a bore 108 whi.ch
fits neatly over the outer surface of the spi.ndle body 10. The
slot 91 is formed through both -the sleeve 106 and the spindle
8. Relative rotation of the sleeve 106 and spindle 8 may be
prevented in any suitable manner, such as by interaction of
opposed longitudinal faces 109 and 110 of the sleeve 106 and
spindle 8 respectively.
Obviously, the sleeve 106 and spindle body 10 need not
be formed separately, but could be formed by a single component.
The spool return spring 4 may be of the clockwork type
and can be secured in any appropriate manner to react between
a stationary part of the assembly and the rotatable spindle
~. Preferably, the inner end of the spring 4 locates within
a slot (not shown) in an adjacent end portion of the spindle
8 and the outer end is secured to a surrounding substantially
cylindrical wall 111 which is formed integral with the adjacent
end plate 18 of the assembly. By way of example, the spring
outer end may be located within a pocket lnot shown) formed in
the surrounding wall 111 and having a restricted opening
through which the spring end cannot be easily withdrawn. That
is, the spring end needs to be moved in the axial direction of
the spindle 8 to enter and escape from that pocket.
Each end cover 55 and 62 may be formed of plastics
material and may be secured in position on the assembly by
snap engagement or other appropriate means and similarly for
the end plates 17 and 18.
In the example shown in figures 16 to 21, the end plate
18 is retained against the adjacent frame end wall 2 through a
plurality of fingers 112 formed integral with the end plate 18
and each of which passes through a respective opening 113 in
the end wall 2 (figure 17 and 18). Those fingers 112 are
located adjacent the outer periphery of the end plate 18 and
are spaced around that periphery. Each finger 112 has a sharp
lip 114 at its terminal end which snap engages with the inner
surface 115 of the end wall 2 as shown in figure 18 to hold
the plate 18 in position against that wall 2. Each wall
opening 113, however, is of a size such that a clearance space
exists at the side of the respective finger 112 which is remote
from the lip 114. The end cover 62 is provided with a plurality
of integral latching fingers 116, each of which is operable to
enter a respective one of those clearance spaces and thereby
390~i
retain the adjacent end plate finger 112 against separati.on
from the frame end wall 2 as shown i.n figure 18.
The end cover 62 is preEerably retained against
separation from the end plate 18 by snap engagement be-tween at
least some of the latching fingers 116 and respective
cooperable parts of the end plate 18. For example, as shown
in figures 17 and 20, each finger 116 extends through a
flexible sti.rrup 117 formed integral with the end plate 18
and has a latching rib 118 which snap engages behind an end
surface 119 of the stirrup 117. The stirrup 117 overlies the
finger 116 and must be forced to flex outwards to allow
subsequent withdrawal of the finger 116 and thereby permit
separation of the cover 62 and end plate 18. Obviously, there
are many other ways in which the desired retention may be
achieved.
As shown in figures 16, 19 and 21, at least one metal
reinforcing strap 120 may extend between and engage the two
end covers 55 and 62 so as to strengthen the assembly. An
opening 121 in one end of the strap 120 engages over a lug
122 formed integral with the end cover 62, and any appropriate
connection may be provided between its opposite end and the
end cover 55.
It will be clear from the preceding description that the
retractor assembly has many valuable advantages both from the
point of view of function and economy of manufacture. The
assembly is particularly suited for production line assembly
methods.
The ratchet wheel, inertia plate and biasing spring
arrangement is particularly advantageous because of the
relatively constant spring force acting between the ratchet
wheel and inertia plate at all rotational positions of the
spindle. In that arrangement the centre of gravity of the
inertia plate passes substantially through the spindle axis
and the detent lever has little or no i.nfluence on the turning
moment applied to the inertia plate.
It is also significant that the detent lever can be
moulded from a plastics or other suitable ma-terial so as -to
enable easy and accurate formation. Accurate formation of the
outer or tooth end of the detent lever permits accurate gating
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o~ that lever with the locking ring thereby minimising or
removing the risk of the pawl not engaging correctly with the
locking ring. In that regard, the tooth end of the detent
lever can be relatively sharp to provide accurate and positive
engagement with the locking ring.
Various alterations, modifications and/or additions
may be introduced into the constructions and arrangements of
parts previously described without departing from the spirit
or ambit of the invention as defined by the appended claims.
