Vehicle seat tract assembly with secondary system

A vehicle seat track assembly includes an elongated fixed track structure constructed and arranged to be fixed to a vehicle floor and a movable track structure cooperable with the fixed track structure. A plurality of rolling elements are engaged between track structures for rollingly supporting the movable track structure on the fixed track structure to enable the movable track structure to be moved in opposite directions through a range of adjusting movements with respect to the fixed track structure. An adjusting mechanism IS operatively associated with the track structures and is constructed and arranged to permit the movable track structure to be moved through the adjusting movements. The adjusting mechanism includes a locking and releasing device constructed and arranged to be moved between (1) a locking position preventing the adjusting movements from being affected and (2) a releasing position wherein the locking and releasing device is operable to release the adjusting mechanism to permit the adjusting movements. A lock and release system is operatively associated with the track structures and includes locking structure movable between a released position permitting the adjusting movements and a locked position preventing the adjusting movements from being affected. The lock and release system includes shock responsive structure constructed and arranged to move the locking structure to the locked position thereof in response to a crash condition which occurs while the locking and releasing device is in the releasing position thereof.

BACKGROUND OF THE INVENTION 
This invention relates to a track assembly of a vehicle seat and, more 
particularly, to an adjustable vehicle seat track assembly having a 
secondary lock system for preventing unwanted fore and aft movement of 
movable tracks of the assembly during a crash condition which may occur 
when the vehicle seat is being adjusted. 
Seat track assemblies are conventional equipment in adjustable vehicle 
seats. Usually, there are two seat track assemblies utilized to adjustably 
support a single vehicle seat. Each seat track assembly comprises 
basically a pair of track structures and a set of rolling elements. The 
rolling elements are utilized to rollingly support a movable one of the 
track structures on a fixed one of the track structures. The fixed track 
structure is typically fixed to the vehicle floor and the movable track 
structure supports a portion of the vehicle seat. The rolling support 
provided by the rolling elements enables the movable track structure with 
the seat attached to be moved fore and aft into a multiplicity of adjusted 
positions. 
With non-powered, manually adjustable seats, manual actuation generally 
involves actuating a pull bar disposed under the seat which moves a 
locking and releasing device from a locking position into a releasing 
position, permitting the movable track structure and the seat mounted 
thereon to be moved into the desired position of adjustment. Once in the 
desired position, the pull bar is released and the locking and releasing 
device returns to the locking position thereof locking the movable track 
structure with respect to the fixed track structure. 
When manually adjustable seats are employed in vehicles, generally, the 
vehicle owner's manual instructs the operator to avoid adjusting the seat 
while the vehicle is operating. However, it has been determined that 
drivers and passengers tend not to heed these warnings and will adjust the 
vehicle seat while the vehicle is in motion. If the vehicle seat is being 
adjusted during vehicle operation and crash condition occurs, injury to 
the passenger may occur as a result of the impact force being transferred 
to the unlocked vehicle seat. 
Accordingly, a need exists to provide a non-powered adjustable vehicle seat 
track assembly which controls movement of the movable track structures in 
response to the sensing of a vehicle crash condition which occurs while 
the primary locking and releasing device is in a releasing position. 
SUMMARY OF THE INVENTION 
An object of the present invention is to fulfill the need referred to 
above. In accordance with the principles of the present invention, this 
objective is obtained by providing a vehicle seat track assembly including 
an elongated fixed track structure constructed and arranged to be fixed to 
a vehicle floor and a movable track structure cooperable with the fixed 
track structure. A plurality of rolling elements are engaged between track 
structures for rollingly supporting the movable track structure on the 
fixed track structure to enable the movable track structure to be moved in 
opposite directions through a range of adjusting movements with respect to 
the fixed track structure. An adjusting mechanism is operatively 
associated with the track structures and is constructed and arranged to 
permit the movable track structure to be moved through the adjusting 
movements. The adjusting mechanism includes a locking and releasing device 
constructed and arranged to be moved between (1) a locking position 
preventing the adjusting movements from being affected and (2) a releasing 
position wherein the locking and releasing device is operable to release 
the adjusting mechanism to permit the adjusting movements. A lock and 
release system is operatively associated with the track structures and 
includes locking structure movable between a released position permitting 
the adjusting movements and a locked position preventing the adjusting 
movements from being affected. The secondary lock and release system 
includes shock responsive structure constructed and arranged to move the 
locking structure to the locked position thereof in response to a crash 
condition which occurs while the locking and releasing device is in the 
releasing position thereof. 
Other objects, features and characteristics of the present invention, as 
well as the function of the related elements of the structure, and the 
combination of the parts and economics of manufacture, will become 
apparent upon consideration of the following detailed description and the 
appended claims with reference to the accompanying drawings, all of which 
form a part of this specification.

DETAILED DESCRIPTION OF THE PRESENTLY PREFERRED EXEMPLARY EMBODIMENTS 
Referring to the drawings, a vehicle seat track system is shown, generally 
indicated at 10, which embodies the principles of the present invention. 
In the illustrated embodiment of FIG. 1, the track system 10 includes a 
pair of spaced track assemblies 11 and 13. Each track assembly 11 and 13 
includes an elongated, fixed track structure 12, and a cooperating 
elongated movable track structure 14. Each basic track assembly also 
includes a plurality of rolling elements 16 (FIG. 6) of the type disclosed 
in the commonly assigned U.S. patent application Ser. No. 08/527,727 filed 
on Sept. 13, 1995, the disclosure of which is hereby incorporated by 
reference into the present specification. With reference to FIG. 1, each 
fixed track structure 12 may be fastened to an associated vehicle seat 
riser 18, and the risers can be fastened directly to a floor of the 
vehicle by bolting. The risers may be of any configuration for securing 
the fixed track structures to the vehicle floor. It can be appreciated 
that the risers 18 could be coupled to a lower set of tracks (not shown) 
mounted in fixed parallel relation on the vehicle floor. The lower tracks 
are operable to provide for the movement of the system 10 to a seat access 
position disposed forwardly of a selected seat operating position 
permitting easy entry to a rear passenger compartment of a vehicle. 
Each fixed track structure 12 is preferably made of sheet steel bent to 
provide a fixed track member including an elongated lower central portion 
22 having a pair of elongated upstanding leg portions 24 extending 
upwardly therefrom terminating in a pair of outwardly flared upwardly 
facing convex portions 26 having depending free end portions 28. Each 
movable track structure 14 is likewise preferably made of sheet steel bent 
to provide a movable track member including an elongated upper central 
portion 30 having a pair of elongated transversely spaced downwardly 
facing convex depressions 32 formed integrally on opposite edges thereof 
and a pair of elongated depending leg portions 34 extending downwardly 
from opposite edges of the convex depressions terminating in a pair of 
downwardly facing convex portions 36 having upstanding free end portions 
38. The movable track structures 14 are constructed and arranged to enable 
a vehicle seat cushion assembly (not shown) to be mounted thereon. 
The track members 12 and 14 are constructed and arranged to be 
telescopically interengaged in cooperating relation to one another so that 
the pair of upwardly facing convex portions 26 of each fixed track member 
12 is disposed below the pair of downwardly facing convex depressions 32 
and above the upstanding free end portions 38 of an associated movable 
track member 14. Preferably, the pair of upwardly facing convex portions 
26 of the fixed track member 12 and the pair of downwardly facing convex 
depressions 32 of the movable track member 14 all provide convexly arcuate 
surfaces. 
Each of the roller elements 16 comprises a roller having an annular groove 
of arcuate cross-sectional configuration formed in a central exterior 
periphery thereof providing arcuate annular surfaces operable to rollingly 
engage the convex arcuate surfaces of an associated downwardly facing 
convex depressions 32 and upwardly facing convex portions 26 respectively 
through a central angular extent thereof, as, for example, 30.degree.. 
Preferably, each of the rollers 16 is made of steel. 
To manually adjust the position of the movable track members with respect 
to the fixed track members, an adjusting mechanism is associated with each 
pair of fixed and movable track members. The adjusting mechanism, 
generally indicated at 40, is of the type disclosed in the 
above-referenced U.S. patent application Ser. No. 08/527,727 wherein a 
locking and releasing device, generally indicated at 42, is provided. As 
best shown in FIG. 7, to accommodate the locking and releasing device 42, 
one of the depending free end portions 28 of the fixed track member 12 is 
formed with a series of equally spaced downwardly opening notches 44. A 
corresponding one of the depending leg portions 34 of the movable track 
member 14 has a plurality of vertically extending parallel slots (not 
shown) formed therein which are spaced apart so as to correspond with the 
spacing of the notches 44. 
The locking and releasing device 42 itself includes a pair of abutting 
metal plates, generally indicated at 46, stamped to provide a plurality of 
spaced abutting notch-entering locking portions 48 extending transversely 
therefrom to extend through and beyond the spaced vertically extending 
slots in the one depending leg portion 34. Preferably, corresponding slots 
are also formed in the corresponding upstanding end portion of the track 
member 14. 
The locking and releasing device 42 also includes a mounting structure 50 
which is preferably in the form of a molded plastic body having a recess 
formed in an outer face thereof which receives the abutting mounting 
portions of the abutting plates 46 therein and a pair of spaced openings 
extending from the recess to an opposite face thereof through which the 
abutting locking portions 48 of the abutting plates 46 extend. As 
disclosed in U.S. patent application Ser. No. 08/527,727, the mounting 
structure 50 is spring biased upwardly into a locking position with the 
locking portions 48 engaged within the notches 44. From the locking 
position, the locking and releasing device 42 may be moved downwardly 
against the spring action into a lower, releasing position. To facilitate 
this movement, as shown in FIG. 1, a manual actuating member, such as 
U-shaped member 52 is coupled between the locking and releasing device 42 
associated with each track assembly 11 and 13. The U-shaped member 52 has 
its legs flattened and is apertured intermediate the flattened ends 
thereof. The aperture in each flattened end rotatably receives a shaft 54 
fixed as by a threaded engagement to the leg portion 34 of the movable 
track member 14. The rearward end of the flattened portion of each leg 
includes a pin 56 which extends laterally therefrom and is engaged within 
a horizontally elongated opening 57 formed in the central exterior portion 
of the mounting structure 50 at a position above the locking plates as 
shown in FIG. 7. Manual upward movement of the U-shaped member 52 causes 
the locking and releasing device 42 to move downwardly against the bias 
thereon into a releasing position with the locking portions 48 removed 
from engagement with the notches 44, thereby permitting fore and aft 
movement of the movable track members 14 through a range of adjusting 
positions. 
Adjustment of the manually movable track assemblies should always be 
performed while the vehicle is not operating. It has been determined, 
however, that many drivers and/or passengers adjust their seats while the 
vehicle is operating. If the locking and releasing device 42 is in its 
releasing position during a crash condition, the force of the impact may 
be transferred to the free moving vehicle seat which may cause injury to 
the seat occupant. 
In accordance with the invention, a lock and release system, generally 
indicated at 58, defining a secondary lock system is operatively 
associated with at least one of the track assemblies 11 and 13. The lock 
and release system 58 includes shock responsive structure, generally 
indicated at 60. With reference to FIG. 2, the shock responsive structure 
in the form of a hydraulic coupling device 60 includes rear bracket 62, a 
front bracket 64 coupled thereto, and a movable member 65 disposed between 
the brackets 62 and 64. The rear bracket 62 is mounted to an inside 
sidewall 66 of at least one of the movable track members 14 so as to be 
movable fore and aft therewith. The movable member 65 is mounted for 
rotational movement with respect to axis A (FIG. 6) and includes an arm 
portion 68 extending therefrom. The arm portion 68 includes an elongated 
slot 70 therein, the function of which will become apparent below. 
With reference to FIG. 5, the movable member 65 defines an interior cavity 
72. A shock responsive member 74 is sealing received within the cavity and 
mounted for rotation in either direction. Portion 75 of member 74 is 
coupled to the movable member 65 such that, under certain conditions, 
movable member 65 will rotate together with the member 74 and under other 
conditions, the member 74 will rotate without causing the movable member 
65 to rotate, as will be explained more fully below. A fluid, such as oil 
76, fills the cavity 72. Member 74 includes female threads 77 which 
receive a screw 78. Screw 78 couples a pinion 80 to the shock responsive 
member 74. Thus, as explained below, rotational motion of the pinion 80 
will cause the member 74 to rotate in cavity 72. The pinion 80 includes a 
plurality of teeth 82 defined in the periphery thereof. The teeth 82 are 
constructed and arranged to mate with teeth 84 defined on a rack 86 which 
is secured to the fixed track structure 12 via bracket 88 (FIG. 6). The 
function of the rack 86 and pinion 88 will become apparent below. 
With reference to FIGS. 4 and 6, the lock and release system 58 includes 
locking structure, generally indicated at 89, which is movable between a 
released position permitting the adjusting movements of the movable track 
members 14 to be affected and a locked position preventing any adjusting 
movements from occurring. The locking structure 89 includes a mounting 
member or structure, generally indicated at 90, which is substantially 
similar to the mounting structure 50 described above. The mounting member 
90 is preferably in the form of a molded plastic body having a recess 
formed in an outer face thereof which receives abutting plates 92 therein 
and a pair of spaced openings extending from the recess to an opposite 
face thereof through which abutting locking portions or members 94 of the 
abutting plates 92 extend, in a manner generally identical to that 
described above with regard to the locking and releasing device 40. The 
locking structure 89 includes a shaft 96 extending generally transversely 
from a side of the mounting structure 90, which is received in the slot 70 
of arm portion 68. 
The mounting member 90 is normally biased downwardly to a released position 
by a centering spring 91 which centers the movable member 65. As best 
shown in FIGS. 2 and 6, the spring 91 is a coiled spring having one end 93 
engaged with extending flange 93 of the bracket 64 while the other end 95 
of the spring 91 is engaged with the movable member 65 such that the 
spring can accommodate movement in opposite directions. The spring 91 is 
constructed and arranged such that in its relaxed condition, the diameter 
of the coils are large and when stressed, the coil diameter becomes 
smaller. With such spring structure, rotation of the movable member 65 
directly affects the spring 91. When the movable member is centered by 
spring 91, the surfaces defining the slot 70 of the arm portion 68 of the 
movable member 65 engage the shaft 96 of the mounting member to maintain 
the locking structure 89 in its released position. In this position, the 
locking portions 94 are released from engagement with the notches 44 
defined in the fixed track member 12, permitting the adjusting movements 
of the movable track members 14 to be affected. 
With reference to FIGS. 2 and 3, it can be appreciated that when the 
movable track members 14 are being adjusted in the fore and aft directions 
with the lock and release system in its released position, the pinion 80 
moves along the rack 86. Such normal movement is generally a slow, 
continuous movement during which the fluid 76 does not transmit the 
movement of the shock responsive member 74 within the cavity 72 with the 
pinion 80 to the movable member 65. Instead, hydraulic slip of the shock 
responsive member 74 occurs (FIG. 5). Thus, the arm portion 68 of the 
movable member 65 will not rotate with the shock responsive member 74 and 
the arm portion is maintained in its normal, generally upright position 
(FIG. 3). Accordingly, the locking structure 89 is disposed in its lower, 
released position. However, if the locking and releasing device 42 of the 
adjusting mechanism is in its releasing position and the movable track 
members 14 are adjusted when a crash condition occurs, the fluid 76 will 
transmit sufficient accelerated movement of the shock responsive member 74 
beyond which occurs by the sudden impulse to the movable member 65. When 
this occurs, the arm portion 68 will rotate together with the shock 
responsive member 74 and pinion 80 clockwise or counter-clockwise 
(depending upon the collision direction), to a position, for example, as 
shown in FIG. 4. This motion, against the bias of spring 91, causes the 
surfaces defining slot 70 to engage and move the shaft 96 and thus the 
mounting member 90 generally upwardly to the locked position thereof. In 
this position, the locking portions 94 of the abutting plates 92 engage 
with the notches 44 in the fixed track member 12 in the manner discussed 
above with regard to the operation of the locking and releasing device 42. 
Thus, the movable track members 14, which are joined via the U-shaped 
member 52, are locked with respect to the fixed track members 12 during 
the collision. Once the sudden impulse is over, the centering spring 91 
biases the movable member 65 and arm portion 68 thereof to the normal, 
centered position which returns the locking structure 89 to its released 
position. 
Although only one lock and release system 42 is shown associated with track 
assembly 11, it can be appreciated that if additional locking is required, 
a lock and release system may be associated with the other track assembly 
13 as well. 
The viscosity of the fluid in cavity 72 has an effect on the speed at which 
movement of the shock responsive member 74 will occur. Consequently, since 
the movement of the shock responsive member and thus the movable member 65 
must overcome the resistance of the centering spring 91, the effect of 
changes in viscosity due to temperature changes can be offset by using a 
temperature sensitive spring. Thus, in the illustrated embodiment, the 
spring 91 is made of 55 NITINOL, a nickel-titanium alloy, to provide the 
offset. With such material, the colder the spring becomes, the stiffer the 
spring gets to compensate for temperature changes of the fluid in cavity 
72. 
It can be appreciated that the lock and release system of the invention 
provides an effective means of securing the movable track members 14 with 
respect to the fixed track members 12 during a crash condition, even when 
the adjusting mechanism is in a releasing position. 
While the invention has been described in connection with what is presently 
considered to be the most practical and preferred embodiment, it is 
understood that the invention is not limited to the disclosed embodiment 
but, on the contrary, is intended to cover various modifications and 
equivalent arrangements included within the spirit and scope of the 
appended claims.