Occupant detection sensor assembly for seats

[0002] 1. Field of the Invention

[0003] The present invention relates generally to seats for motor vehicles and, more specifically, to an occupant detection sensor assembly for a seat in a motor vehicle.

[0004] 2. Description of the Related Art

[0005] It is known to provide seats for motor vehicles such as an automotive vehicle. Typically, a seat includes a generally horizontal seat cushion portion and a generally vertical seat back portion operatively connected to the seat cushion portion.

[0006] It is also known to provide a seat weight sensor for the seat cushion portion of the seat in a motor vehicle. For example, the seat weight sensor may be of a bladder type that requires a silicone-filled bladder be added to the seat cushion portion. The seat weight sensor measures changes in the pressure of the silicone-filled bladder and uses the output to infer the weight of an occupant sitting in the seat. In another example, a seat weight sensor uses a mat covered with force sensitive resistors installed inside a seat foam of the seat cushion portion to measure pressure distribution across the mat. The output of the seat weight sensor is used to infer occupant size. In still another example, a seat weight sensor uses a light source and a light detector inside the seat foam of the seat cushion portion to detect compression of the seat foam. Compressed seat foam generates a different light intensity than uncompressed seat foam. In the seat weight sensor, multiple light sources and detectors allow an approximation of weight distribution of the seat cushion portion to be calculated.

[0007] One disadvantage of the above seat weight sensors is that a bladder or matt is needed, which is undesired. Another disadvantage is that the seat weight sensors require components to be disposed inside the seat cushion portion, which is undesired. A further disadvantage is that the above seat weight sensors are used to measure the weight of an occupant and not for detecting an occupant in the seat.

[0008] Accordingly, the present invention is an occupant detection sensor assembly for a seat in a motor vehicle including a generally horizontal seat cushion portion operatively connected to vehicle structure and a generally upright seat back portion operatively connected to the seat cushion portion. The occupant detection sensor assembly includes a seat cushion disposed within the seat cushion portion of the seat having at least one channel therein. The occupant detection sensor assembly also includes at least one sensor connected to the seat cushion and communicating with the at least one channel and an electronic controller electrically connected to the at least one sensor for detecting an occupant seated on the seat cushion portion.

[0009] One advantage of the present invention is that an occupant detection sensor assembly is provided for a seat in a motor vehicle. Another advantage of the present invention is that the occupant detection sensor assembly detects or classifies an occupant in the seat, either their presence, their size, or their humanness. Yet another advantage of the present invention is that the occupant detection sensor assembly uses the seat foam itself as the medium for the sensor elements. Still another advantage of the present invention is that the occupant detection sensor assembly does not require components, other than sensors, to be disposed inside the seat cushion portion of the seat.

[0010] Other features and advantages of the present invention will be readily appreciated, as the same becomes better understood after reading the subsequent description when taken in conjunction with the accompanying drawings.

[0011] FIG. 1 is a perspective view of an occupant detection sensor assembly, according to the present invention, illustrated in operational relationship with a seat.

[0012] FIG. 2 is a sectional view taken along line 2—2 of FIG. 1.

[0013] FIG. 3 is a side elevational view of the occupant detection sensor assembly of FIG. 1.

[0014] Referring now to the drawings and in particular FIGS. 1 through 3, one embodiment of an occupant detection sensor assembly 10, according to the present invention, is shown for a seat, generally indicated at 12, of a motor vehicle (not shown). The seat 12 includes a generally horizontal seat cushion portion 14 and a generally upright seat back portion 16 pivotally connected to the seat cushion portion 14 by a seat back pivot 17. The seat cushion portion 14 includes a seat pan (not shown) and a seat cushion 18 operatively connected to the seat pan by suitable means such as an adhesive. The seat back portion 16 includes a seat back frame (not shown) and a back cushion 20 disposed about and operatively connected to the seat back frame by suitable means such as an adhesive. The seat 12 includes a track or lower seat frame member 22 mounted to the seat pan and vehicle structure 24 such as a floorpan. It should be appreciated that, except for the occupant detection sensor assembly 10, the seat 12 is conventional and known in the art.

[0015] As illustrated in FIGS. 1 through 3, the occupant detection sensor assembly 10 includes the seat cushion 18 being made of a foam material such as a polyurethane foam. The seat cushion 18 has at least one, preferably a plurality of capillaries or channels 26 disposed therein. The channels 26 are integral to the foam material. Each of the channels 26 forms a closed loop and has a generally circular shape, but may have any suitable shape. The channels 26 have a generally circular cross-sectional shape, but may have any suitable cross-sectional shape. In the embodiment illustrated, the channels 26 are concentric relative to each other. Also, the channels 26 are divided into concentric sets of three thereof and spaced laterally. It should be appreciated that the channels 26 may be non-concentric and not disposed concentric or about each other. It should also be appreciated that the layout of the channels 26 can be customized for optimal sensing in a given seat configuration.

[0016] The occupant detection sensor assembly 10 also includes at least one, preferably a plurality of sensors 28 connected to and cooperating with the channels 26. The sensors 26 are of a pressure sensing type. In the embodiment illustrated, one sensor 28 is associated with one channel 26. The sensors 28 are connected by suitable means such as wires 30 to a source of power such as a controller 32 to be described. It should be appreciated that the sensors 28 are disposed inside the seat cushion 18 and that the wires 30 extend from the sensors 28 through the seat cushion 18. It should also be appreciated that the output from the sensors 28 can be absolute weight in pounds or to generate weight distribution that can be used for occupant classification. It should further be appreciated that the medium inside the channels 26 of the foam material of the seat cushion 18 becomes the medium for pressure sensing.

[0017] The occupant detection sensor assembly 10 further includes an electronic control unit (ECU) 32 connected by the wires 30 to each of the sensors 28. The ECU 32 is disposed below the seat cushion 18 and mounted to suitable structure such as the seat pan. The wires 30 extend from the ECU 32 through the seat cushion 18 to the sensors 28. The ECU 32 receives signals from the sensors 28 and sends a signal to an electronic controller 34 such as an air bag or restraint control module. It should be appreciated that the ECU 32 is connected by at least one circuit to the electronic controller 34. It should also be appreciated that the ECU 32 and electronic controller 34 are conventional and known in the art.

[0018] The occupant detection sensor assembly 10 may include a fluid in the channels 26 of the seat cushion 18. The fluid may be air, a liquid or a gel such as silicone. The sensors 28 sense a change in pressure of the fluid when the seat cushion 18 is compressed. It should be appreciated that, in the preferred embodiment, the fluid is air and the sensors 28 detect a change in pressure of the air in the channels 26.

[0019] In operation of the occupant detection sensor assembly 10, when the seat 12 is unoccupied, the sensors 28 measure a base pressure of the fluid in the channels 26. When an occupant sits in the seat 12, the seat cushion 18 is compressed, causing an increased pressure in the fluid of the channels 26. The sensors 28 sense or measure the difference in pressure and sense signals to the ECU 32. The ECU 32 processes the signals from the sensors 28 and a signal is sent to the electronic controller 34. The electronic controller 34 uses this signal in determining whether an occupant is seated in the seat 12. It should be appreciated that, when the occupant exits the seat 12, the seat cushion 18 expands to its original position and the pressure of the fluid in the channels 26 returns to the base value.

[0020] The present 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 rather than of limitation.

[0021] Many modifications and variations of the present invention are possible in light of the above teachings. Therefore, within the scope of the appended claims, the present invention may be practiced other than as specifically described.