Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
CA 02546400 2006-05-12
INERTIA CATCH FOR DOOR LATCHES
Field of the Invention
[0001] The invention relates to a latch assembly for selectively locking a
motor vehicle
door. More particularly, the invention relates to a latch assembly having an
inertia lever for
preventing a ratchet from releasing a striker in the event of a motor vehicle
impact.
Description of Related Art
[0002] Motor vehicles include hinged doors for selectively providing access to
motor
vehicle passenger or cargo compartments. Typically, a latch mechanism is
coupled between one
of the doors and a motor vehicle body for releasably locking the door in a
closed position. A
release mechanism is typically coupled to the latch mechanism for locking and
unlocking the
latch mechanism. It remains desirable to provide a mechanism for preventing
the latch
mechanism from unlocking during a side impact of the motor vehicle.
Summary of the Invention
[0003] According to one aspect of the invention, a latch assembly selectively
engages a
striker for latching a door to a motor vehicle body. A ratchet is rotatably
mounted to the housing
for movement between an engaged position engaging the striker and a release
position. A pawl
is rotatably mounted to the housing and is engageable with the ratchet to
retain the ratchet in the
engaged position. An inertia catch is coupled to the housing and operably
coupled to the pawl
for preventing the pawl from moving out of engagement with the ratchet in the
event of a motor
vehicle impact.
[0004] According to another aspect of the invention, a latch assembly
selectively engages
a striker for latching a door to a motor vehicle body. The latch assembly
includes a housing, a
ratchet rotatably mounted to the housing for movement between an engaged
position engaging
the striker and a release position, and a pawl rotatably mounted to the
housing and engageable
with the ratchet to retain the ratchet in the engaged position. An auxiliary
pawl lever is rotatably
mounted to the housing and operably connected to the pawl for moving the pawl
out of
engagement with the ratchet. An inertia lever is rotatably mounted to the
housing and includes a
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lip engageable with the auxiliary pawl lever in the event of a motor vehicle
impact to prevent the
auxiliary pawl lever from moving the pawl out of engagement with the ratchet.
[0005] According to yet another aspect of the invention, a latch assembly
includes a
housing, a ratchet rotatably mounted to the housing for movement between an
engaged position
engaging the striker and a release position, and a pawl rotatably mounted to
the housing and
engageable with the ratchet to retain the ratchet in the engaged position. A
plunger is operably
coupled to the pawl and movable between a rest position and an extended
position in which the
pawl is moved out of engagement with the ratchet to allow the ratchet to move
into the release
position. An inertia lever is engageable with the plunger in response to a
motor vehicle impact
for preventing the plunger from moving into the extended position.
Brief Description of the Drawings
[0006] The present invention will be readily appreciated as the same becomes
better
understood by reference to the following detailed description when considered
in connection
with the accompanying drawings wherein:
[0007] Figure 1 is a fragmentary, perspective view of a motor vehicle
including a latch
assembly according to the invention fixedly mounted along a door;
[0008] Figure 2 is a perspective view of the latch assembly including a
ratchet engaging a
striker and a pawl abutting the ratchet along a first side of a housing;
[0009] Figure 3 is a perspective view of the latch assembly including the pawl
retaining
the ratchet in a release position;
[0010] Figure 4 is an exploded, perspective view of the latch assembly
including an
auxiliary pawl lever disposed along a second side of the housing;
[0011] Figure 5 is an elevational, side view including the auxiliary pawl
lever, which is
coupled to the pawl, and an inertia lever disposed along the second side of
the housing;
[0012] Figure 6 is an elevational, side view of the second side of the housing
including
the auxiliary pawl lever pivoted away from the inertia lever;
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[0013] Figure 7 is an elevational, side view of the second side of the housing
including a
projection of the auxiliary pawl lever engaging a lip of the inertia lever
during a motor vehicle
impact;
[0014] Figure 8 is a perspective view of a latch assembly according to a
second
embodiment of the invention including the inertia lever abutting a first end
of a plunger;
[0015] Figure 9 is a perspective view of the latch assembly including the
first end of the
plunger clearing the hook of the inertia lever to rotate the auxiliary pawl
lever and allow
movement of the ratchet into the release position; and
[0016] Figure 10 is a perspective view of the latch assembly including the
hook of the
inertia lever engaging the first end of the plunger to prevent rotation of the
auxiliary pawl lever.
Detailed Description of the Preferred Embodiments
[0017] Referring to Figure 1, a motor vehicle, generally indicated at 10,
includes a body
portion 12 and a door 14 pivotally hinged to the body portion 12 for movement
between an open
position and a closed position. A latch assembly, generally shown at 16, is
fixedly mounted to
the door 14 and selectively engages a striker 18 mounted along the body
portion 12. A detailed
description of the structure and function of the latch assembly 16 is
disclosed in Applicant's
United States patent application serial number 11/007,946 filed on December 9,
2004, which is
incorporated herein by reference in its entirety.
[0018] The latch assembly 16 includes a housing 20 having a first side 22,
shown in
Figures 2 and 3, and an opposing second side 24, shown in Figure 4. Referring
to Figures 2 and
3, a plurality of peripheral walls 26 extends along the first side 22 of the
housing 30 and defines
a cavity 28. A frusto-trapezoidal aperture 30 bisects the first side 22 of the
housing 20. The
aperture 30 is designed to receive the striker 18. A seal 32, preferably
formed from a flexible
rubber material, is mounted or otherwise integrally formed with the housing 20
at an open end of
the aperture 30. An elastomeric or rubber bumper 34 including a shoulder 36 is
fixedly mounted
at an opposing end of the aperture 30 for receiving and absorbing the impact
of the striker 18,
thereby reducing stresses on the latch assembly 16 and reducing noise. A
channel 35 extends
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from the cavity 28 of the first side 22 to the exterior of the housing 20 for
providing a water
outlet for the latch assembly 16.
[0019] A ratchet 38 and a pawl 40 are disposed within the cavity 28. The
ratchet 38 and
the pawl 40 are preferably constructed from metal and partially covered with a
plastic material in
order to reduce noise during latch operation. Certain portions that are
subject to wear, such as a
shoulder 39 of the ratchet 38 and a shoulder 41 of the pawl 40, are not
covered by plastic.
[0020] The ratchet 38 is rotatably mounted to the first side 22 of the housing
20 via a pin
42 for movement between an engaged position, in which a hook portion 44 of the
ratchet 38
engages the striker 18, and a release position, in which the ratchet 38
releases the striker 18 to
allow opening of the door 14. A spring (not shown) biases the ratchet 38 into
the release
position. The angular travel of the ratchet 38 about the pin 42 is delimited
by the shoulder 36
and a wall 46.
[0021] The ratchet 38 also includes a lip 48 for selectively engaging a switch
50 disposed
within a recess 51 formed along the housing 20. More specifically, as the
ratchet 38 moves from
the engaged position to the release position, the lip 48 urges against a leaf
spring 52 in order to
change the state of the switch 50. The switch 50 includes a plurality of
terminals attached to a
wiring harness (not shown) that is disposed in and extends from a tubular
construct 53 formed in
the housing 20.
[0022] The pawl 40 is rotatably mounted along the first side 22 of the housing
20 via a
pin 54. When the pawl 40 is in a pawl engagement position, as shown in Figure
2, the pawl 40
retains the ratchet 38 in the engaged position. When the pawl 40 is moved out
of the pawl
engagement position, the ratchet 38 is free to move from the engaged position
to the release
position. A spring 56 is disposed within a groove 58 for biasing the pawl 40
into the pawl
engagement position.
[0023] Refernng to Figure 4, the second side 24 of the housing 20 includes
upper 60 and
lower 61 cavities. A tubular post 62 is disposed within the upper cavity 60
and encompasses the
pin 54 extending through the opposing first side 22 of the housing 20. An
auxiliary pawl lever
64 is pivotally mounted about the tubular post 62. The auxiliary pawl lever 64
includes an
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aperture 65 for receiving the tubular post 62 therethrough. The auxiliary pawl
lever also includes
a slot 66 for receiving a projection 68, shown in Figures 5 through 7, of the
pawl 40, which
extends through an aperture 69 in the housing 20. Thus, the auxiliary pawl
lever 64 is operably
coupled to the pawl 40. The auxiliary pawl lever 64 also includes an abutment
70 and a
protrusion 72.
[0024] Referring back to Figure 4, an outside release lever 74 is also
pivotally mounted
about the tubular post 62. The outside release lever 74 includes a slot 76 and
is coupled to the
auxiliary pawl lever 64 by a slidable link 78. The slidable link 78 includes a
tab 80 that slides in
and out of the slot 76. A toggle spring 82 biases the link 78 either into or
out of the slot 76.
When the tab 80 is adjacent an open end of the slot 76, the link 78 is in the
unlocked position.
When the link 78 is in the unlocked position, rotation of the outside release
lever 74 causes the
tab 80 to engage the auxiliary pawl lever 64 so that the auxiliary pawl lever
64 rotates. Since the
pawl 40 is coupled to the auxiliary pawl lever 64, rotation of the auxiliary
pawl lever 64 causes
the pawl 40 to move out of the pawl engagement position. As a result of this
rotation, the ratchet
38 moves to the release position and releases the striker 18. On the other
hand, when the tab 80
is adjacent a closed end of the slot 76, the link 78 is in the locked
position. When the link 78 is
in the locked position, the outside release lever 74 will rotate relative to
the auxiliary pawl lever
64 and the ratchet 38 remains in the engaged position.
[0025] The link 78 is actuated by a lock link lever 84, which in turn is
actuated by a key
cylinder lever 86 connected to a key cylinder (not shown). The lock link lever
84 includes a
shelf 88 with side ridges. The key cylinder lever 86 is seated in the shelf 88
and has an angular
freedom of motion of about 20 degrees ("lost motion") before the key cylinder
lever 86 engages
one of the side ridges and imparts rotational motion to the lock link lever
84. The lock link lever
84 also includes an aperture 90, which receives a coupling projection 92
depending from the link
78. As a result, the link 78 is kinematically coupled to the lock link lever
84 and the key cylinder
lever 86. Consequently, only a full rotation of the key cylinder lever 86
causes the link 78 to
move between the locked and unlocked positions. A switch 94 is capable of
indicating any of
three positions of the key cylinder: neutral, unlock and lock.
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[0026] An inside lock lever 96 and an inside release lever 98 are coupled to
the key
cylinder lever 86 and the auxiliary pawl lever 64, respectively. More
specifically, the inside
release lever 98 includes a foot 100 that abuts an appendage 102 of the
auxiliary pawl lever 64.
The inside release lever 98 also includes a toe 104 for engaging a pedal 106
of the inside lock
lever 96 in order to unlock the inside lock lever 96 when the inside release
lever 98 is actuated.
[0027] Referring to Figures 5 through 7, the latch assembly 16 includes an
inertia catch,
generally indicated at 108, for preventing the ratchet 38 from releasing the
striker 18 in the event
of a sudden acceleration above a predetermined threshold. In the current
embodiment, the inertia
catch 108 is an inertia lever having a predetermined mass and rotatably
mounted about a pin 110
for movement in and out of a rest position, shown in Figure 5. The inertia
lever 108 is biased
into the rest position by a spring 112.
[0028] The inertia lever 108 includes a lip 114 that selectively engages the
protrusion 72
of the auxiliary pawl lever 64. In normal operation of the latch assembly 16,
i.e., when the
outside 74 or inside 98 release levers are actuated, the auxiliary pawl lever
64 and the inertia
lever 108 pivot about the respective tubular post 62 and pin 110 at
approximately the same rate
such that the protrusion 72 clears the lip 114, as shown in Figure 6. As a
result, the auxiliary
pawl lever 64 urges the pawl 40 out of the pawl engagement position, which
causes the ratchet
38 to move into the release position and release the striker 18.
[0029] In the event of a motor vehicle impact, the auxiliary pawl lever 64
will rotate at a
very fast rate. But due to the mass of the inertia lever 108, the rotation of
the inertia lever 108
lags behind the rotation of the auxiliary pawl lever 64. As a result, the lip
114 engages the
protrusion 72, as shown in Figure 7, to stop the rotation of the auxiliary
pawl lever 64.
Therefore, the pawl 40 does not move out of the pawl engagement position and
the ratchet 38
remains in the engaged position. As a result, the striker 18 is not released
and the door 14 does
not inadvertently open from the motor vehicle impact.
[0030] Refernng to Figures 8 through 10, wherein like primed reference
numerals
represent similar elements as those described above, the inertia lever 108'
according to a second
embodiment of the invention is disposed within a cavity 116 of a housing
member 118. The
inertia lever 108' has a predetermined mass and is rotatably mounted to a pin
120 for movement
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in and out of a neutral position, shown in Figure 8. A torsion spring 122 is
disposed around the
pin 120 for biasing the inertia lever 108' into the neutral position. The
inertia lever 108' includes
a hook 124, a distal end 126 opposite the hook 124, and a curved surface 128.
[0031) A plunger 130 is disposed within the cavity 116 of the housing member
118 for
selective engagement with the inertia lever 108'. The plunger 130 includes a
first end 132 that
abuts a ramp 134 of the auxiliary pawl lever 64'. The first end 132 is
preferably rounded to
allow for travel of the plunger 130 up and down the ramp 134 between a rest
position, shown in
Figure 8, and an extended position, shown in Figure 9. The plunger 130 also
includes a second
end 136 that abuts the hook 124 of the inertia lever 108'.
[0032] During normal operation, the auxiliary pawl lever 64' is rotated as one
of the
outside 74' and inside 98' release levers is actuated. The rotation of the
auxiliary pawl lever 64'
urges the first end 132 of the plunger 130 up the ramp 134 against the bias of
a spring 138, which
in turn pushes the second end 136 of the plunger 130 in the direction of arrow
A, shown in
Figure 8, against the hook 124. As the plunger 130 moves in the direction of
arrow A, it urges
rotation of the inertia lever 108' about the pin 120. As a result, the second
end 136 of the
plunger 130 and the hook 124 roll against one another at approximately the
same rate such that
the second end 136 of the plunger 130 clears the hook 124 and reaches the
extended position, as
shown in Figure 9. Thus, the auxiliary pawl lever 64' is able to rotate past
the first end 132 of
the plunger 130 to urge the pawl 40' out of the pawl engagement position,
which allows the
ratchet 38' to move into the release position.
[0033] In the event of a motor vehicle impact, the plunger 130 is quickly
forced in the
direction of arrow A, shown in Figure 8. But due to the mass of the inertia
lever 108', the
rotation of the inertia lever 108' lags behind the movement of the plunger
130. As a result, the
hook 124 engages the second end 136 of the plunger 130, which stops the first
end 132 from
moving up the ramp 134 and prevents the rotation of the auxiliary pawl lever
64'. Therefore, the
pawl 40' is not able to move out of the pawl engagement position, which in
turn prevents the
ratchet 38' from moving to the release position.
[0034] The invention has been described in an illustrative manner. It is to be
understood
that the terminology, which has been used, is intended to be in the nature of
words of description
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rather than of limitation. Many modifications and variations of the invention
are possible in light
of the above teachings. Therefore, within the scope of the appended claims,
the invention may
be practiced other than as specifically described.
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