BACKGROUND OF THE INVENTION
This application claims priority to U.S. Provisional Application Serial No. 60/466,933, filed Apr. 30, 2003 and U.S. Provisional Application Serial No. 60/517,581, filed Nov. 5, 2003.
This invention relates to vehicle occupant weight sensing and classification and more particularly to occupant weight sensing and classification in an adjustable seat.
An automotive car seat typically includes a seat base and a seat back and is mounted to an automobile chassis by a support arrangement. In an adjustable automotive car seat, the support arrangement is usually movable by means of electric motors and connected to the seat by four pivoted links. One example is shown in WO 02/074575.
Generally, it is sometimes desirable to determine the weight, classification and position of an occupant of a seat in a vehicle passenger compartment. For example, based upon the weight of the occupant and the position of the occupant on the seat, an active safety restraint system may determine whether or not to deploy or may determine the amount of force with which to deploy. One way of achieving this is by using a plurality of load cells mounted beneath the vehicle seat.
Prior art implementations of weight sensors in adjustable vehicle seats have had some drawbacks. For example, implementing weight sensors in adjustable vehicle seats has often required a complete redesign of the vehicle seat structure in order to accommodate the sensors. Also, many of the prior art designs leave the sensors vulnerable to severe overloads in the event of a collision, such that the sensors would have to be replaced at additional cost.
- SUMMARY OF THE INVENTION
The use of weight sensors below the vehicle seat has also been complicated by the over-cinching of the seat belt. If the seat belt is cinched tightly on a child seat, this increases the weight reading on the weight sensors. The increase in weight on the sensors by the cinched seat belt could incorrectly lead to the determination that an adult is in the vehicle seat. To overcome this problem, some systems incorporate a belt load sensor, which measures the tension in the seat belt so that it can be subtracted from the weight sensors reading to determine the occupant weight. However, the belt load sensor increases the overall cost of the system.
The present invention provides an improved adjustable seat with weight sensors. The invention could be applied to both a manual adjustable seat and a power adjustable seat. Therefore, unless otherwise specified, the term “adjustable” is intended to include manual and power adjustable seats.
The present invention provides an improved vehicle seat subframe assembly that can be installed in existing adjustable vehicle seat designs without substantial modification. The subframe assembly includes a subframe to which are attached a plurality of seat height adjuster links and a plurality of weight sensors. The subframe assembly is adapted to be mounted between the vehicle seat and a seat slide assembly. In one embodiment, the seat height adjuster links are connected to the seat slide assembly and the weight sensors contact the vehicle seat. In another embodiment, the seat height adjuster links are connected to the vehicle seat and the weight sensors contact the seat slide assembly. Overload bolts provide gaps that protect the weight sensors from being overloaded in the event of a collision.
BRIEF DESCRIPTION OF THE DRAWINGS
In either embodiment, the seat occupant weight sensors are safe when abnormal force acts on the seat. The gap between the rigid frame and the seat base protects sensors from being overloaded. Within a predetermined range the seat occupant weight sensors experience restricted seat displacement relative to the support arrangement. This is especially true for power adjustable seats. Use of the vehicle seat subframe of the present invention in an existing adjustable seat design causes little or no increase in overall seat height.
Other advantages of the present invention can be understood by reference to the following detailed description when considered in connection with the accompanying drawings wherein:
FIG. 1 is a schematic representation of a vehicle seat assembly according to a first embodiment of the present invention.
FIG. 2 is a perspective view of the seat subframe assembly and seat slide assembly from FIG. 1.
FIG. 3 is an enlarged bottom perspective view of one front corner the assembly of FIG. 2.
FIG. 4 is an enlarged bottom perspective view of one rear corner of the assembly of FIG. 2.
FIG. 5 is an enlarged top perspective view of the rear corner of the assembly of FIG. 4.
FIG. 6 is a sectional view along lines 6-6 of FIG. 5.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
FIG. 7 is a schematic view of a vehicle seat assembly according to a second embodiment of the present invention.
A vehicle seat assembly 10 according to a first embodiment is shown schematically in FIG. 1. A seat subframe assembly 12 is mounted below a vehicle seat base 14 and seat back 16 and above lower tracks 20 (one shown). The schematic of FIG. 1 shows the components stacked on upon another for clarity, although it should be recognized that in reality there is substantial overlap, such that the overall height of the vehicle seat assembly 10 is not increased.
The seat subframe assembly 12 includes a subframe 22 connected to lower ends of a plurality of seat height adjustment links 24. The seat subframe assembly 12 further includes a plurality of weight sensors 26 mounted to the subframe 22. The weight sensors 26 measure weight between the subframe 22 and an upper seat slide assembly 28.
A perspective view of the seat subframe assembly 12 (without the seat height adjustment links 24) and upper seat slide assembly 28 is shown in FIG. 2. The plurality of weight sensors 26 are mounted in mounting sleeves 30 formed at the corners of the subframe 22. A plurality of mounting tabs 34 are formed in the subframe 22 for attaching to the lower ends of the seat height adjustment links 24 (FIG. 1).
The upper seat slide assembly 28 includes a pair of seat track slides 40 connected at the front by a front cross member 42 and at the rear by a rear cross member 46. The rear cross member 46 is attached to the rear of the seat slides 40 by rear thrust brackets 48. Shoulder bolts 54 attach the rear thrust brackets 48 and seat belt attachment brackets 50 to the seat slides 40.
FIG. 3 is an enlarged bottom perspective view of one front corner of seat subframe assembly of FIG. 2. As can be seen in FIG. 3, each of the front weight sensors 26 is attached to a mounting hole 60 in the front cross member 42. The front weight sensors 26 measure weight between the subframe 22 and the front cross member 42.
FIG. 4 is an enlarged bottom perspective view of one rear corner of the seat subframe assembly of FIG. 2. As can be seen in FIG. 4, each rear weight sensor 26 is attached to a mounting hole 64 in one of the rear thrust bracket 48. The rear weight sensors 26 measure weight between the subframe 22 and the rear thrust brackets 48.
FIG. 5 is an enlarged top perspective view of the rear corner of the seat subframe assembly of FIG. 4. FIG. 6 is a sectional view along lines 6-6 of FIG. 5. Referring to FIGS. 5 and 6, the subframe 22 includes two weight sensor brackets 66 (one shown) at its rear end protruding beyond the seat. The mounting sleeves 30 are each on a weight sensor bracket 66. This provides seat belt attachment points mechanically linked to the suspended part of the subframe 22. There is a clearance of approximately 3 mm between the bottom face of the weight sensor bracket 66 and the top face of the seat track slide 40. Such a kinematical arrangement of the seat belt attachment points allows elimination of seat belt tension sensors.
The two shoulder bolts 54 are firmly attached to the rear end of each seat track slide 40. The shoulder bolts 54 go through holes 68, 69 in the seat belt attachment bracket 50 and the weight sensor bracket 66. The holes 68, 69 in the seat belt attachment bracket 50 and weight sensor bracket 66 are slightly larger than the diameter of the shoulder bolts 54 to provide a guaranteed clearance relative to the shoulder of the shoulder bolt 54. There is also a clearance between the head of the shoulder bolt 54 and the upper surface of the seat belt attachment bracket 50 and between the shoulder bolt 54 and the upper surface of the weight sensor bracket 66. Both clearances are important in order to avoid measured force offload in operation. The clearances offload force from the weight sensors 26 in the event of a crash or other unusually high force that would otherwise damage the sensors 26.
FIG. 7 is a schematic view of a vehicle seat assembly 110 according to a second embodiment of the present invention. The vehicle seat assembly 110 includes a seat subframe assembly 112 again including a subframe 122 to which are mounted a plurality of weight sensors 126 and the upper ends of a plurality of seat height adjustment links 124. In this embodiment, the weight sensors 126 engage the seat base 114, while the seat height adjustment links 124 connect to the upper seat slide assembly 128.
In accordance with the provisions of the patent statutes and jurisprudence, exemplary configurations described above are considered to represent a preferred embodiment of the invention. However, it should be noted that the invention can be practiced otherwise than as specifically illustrated and described without departing from its spirit or scope.