JP3451371B2 - Car occupant weight detection system - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an automobile occupant weight detection system.

[0002]

2. Description of the Related Art In recent years, the occurrence of a secondary accident due to the operation of an air bag of an automobile has become a problem. Are due to being the same.

Therefore, in the automobile industry, in order to protect an occupant from the above-mentioned secondary accident, a means for detecting the weight of the occupant and the position of the center of gravity of the occupant and controlling the airbag operation based on the data is added to the automobile. I am trying.

However, there is currently no vehicle occupant weight detection system for detecting the weight and the position of the center of gravity of the occupant with high accuracy.

[0005]

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a vehicle occupant weight detection system for detecting the weight of an occupant with high accuracy, and the weight and center of gravity of the occupant with high accuracy. An object of the present invention is to provide a vehicle occupant weight detection system for detecting the weight.

[0006]

(Invention of Claim 1) A vehicle occupant weight detection system according to the present invention comprises two or more load detecting capacitances in a seat portion of an occupant seat of an automobile. In a weight detection system for a vehicle occupant, in which a weight sensor and a center of gravity of an occupant when the seat type sensor is displaced in the front-rear direction and is seated can be detected, a variable capacitance section constituting a capacitance type sensor Is formed by providing a gap between the upper and lower electrodes, and a common insert panel having a protrusion projecting downward is arranged above the variable capacitance section, and the protrusion has a variable static capacitance. The position of the insert panel in a plan view is constrained so as to correspond to the central portion of the upper steel plate electrode plate that constitutes the capacitance portion. (Invention of Claim 2) The weight detection system for an automobile occupant of the present invention relates to the invention of Claim 1 above, wherein the electrostatic capacitance type sensor is configured by combining fixed resistors with variable / fixed electrostatic capacitance portions. It has two time constant circuits and inputs the outputs from these both time constant circuits to a logic IC, and further inputs a square wave or sine wave input clock synchronized with both time constant circuits. The duty% of the output clock of the logic IC is changed according to the change of the time constant of the time constant circuit accompanying the change of the electrostatic capacitance of the variable electrostatic capacitance section due to the weight. (Invention of Claim 3) The weight detection system for an automobile occupant of the present invention relates to the invention of Claim 1 above, wherein the electrostatic capacity type sensor comprises a variable / fixed electrostatic capacity section combined with a fixed resistance. There are two time constant circuits and the outputs from both time constant circuits are input to the logic IC. Further, the input clock of a square wave or a sine wave whose phase is shifted is input to each time constant circuit. The duty% of the output clock of the logic IC is changed according to the change of the time constant of the time constant circuit accompanying the change of the electrostatic capacitance of the variable electrostatic capacitance section due to the weight of the occupant.

The functions of the vehicle occupant weight detection system of the above invention will be described in detail in the section of the following embodiments of the invention.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 shows a seat of an automobile having a weight detection system, and FIG. 2 is an exploded perspective view of the seat. [Overall structure of weight detection system for vehicle occupants]
As shown in FIGS. 1 and 2, this vehicle occupant weight detection system is configured by disposing four capacitance type sensors S in a seat portion Z of a seat of an automobile. As shown in FIGS. 2 and 3, specifically, the seat portion Z includes a frame F, the capacitance type sensors S arranged at the four corners of the frame F, and above the capacitance type sensor S. The insert panel IP is arranged, the pad P placed on the insert panel IP, and the decorative cover C enclosing all the above-mentioned structures. The seat Z of the seat as described above has a slide rail SR with respect to a leg L fixed to the floor as shown in FIG.
It can be moved back and forth via. [Structure of Frame F ] As shown in FIG. 2, the frame F is mounted on the leg portion L via the slide rail SR, and has good reproducibility in weight measurement by the capacitance type sensor S. It has high rigidity in order to make it. Note that the frame F can be replaced with a dish-shaped pan as long as it has rigidity and can securely fix the capacitance type sensor S. [About capacitance type sensor S] Capacitance type sensor S
Is, as shown in FIG. 4, variable / fixed capacitance units C1 and C.
2 are combined with fixed resistors R1 and R2 to form time constant circuits T1 and T2, respectively.
EX-OR logic IC [code R
The input clock CLI, which is a synchronized square wave or sine wave, is input to the time constant circuits T1 and T2. In the capacitance sensor S, the output from the EX-OR logic IC [code RIC] is input to the low pass filter LF to be converted into an analog output.

As shown in FIG. 3, the variable capacitance section C1 includes a substrate 1 on which an electrode 10 is arranged, and the substrate 1 described above.
An electrode plate 2 made of a steel plate arranged in parallel above and grounded (0 V), a spacer 3 for providing a gap G between the electrode 10 and the electrode plate 2, the substrate 1, the electrode plate 2 and a spacer 3 is integrated with the rivet 4, and is fixed to the above-mentioned frame F in such a manner that the substrate 1 is in contact therewith. It should be noted that, as shown in FIG. 3, the components of the capacitance type sensor S other than the variable capacitance section C1 (fixed capacitance section C2, fixed resistors R1, R2, EX-
OR logic IC [RIC] etc.) is also arranged.

Therefore, in this capacitance type sensor S, as shown in FIG. 5, the pressing force by the occupant weight acts on the electrode plate 2 through the insert panel IP, and the electrode plate 2 is transformed into the electrode 10. When approaching in a mode, the duty do% of the output clock CLO of the EX-OR logic IC [RIC] changes in accordance with the change of the time constant of the time constant circuit T1 as shown by the solid line and the chain double-dashed line in FIG. As a result, the change in capacitance of the variable capacitance C1 caused by the pressing force can be detected as a change in voltage output. And
The change in the voltage output is output as an analog voltage output by the low pass filter LF.

Further, in this automobile seat, four electrostatic capacity type sensors S are provided, and this outputs the outputs of the four electrostatic capacity type sensors S as shown in FIG.
By inputting to C, four capacitance type sensors S
The weight of the occupant sitting on the seat can be measured by summing the voltage outputs from the seats, and the seats are seated according to the magnitude of the voltage output from each of the four capacitive sensors S. The position of the center of gravity of the occupant can be detected to some extent. [Structure of Insert Panel IP ] The insert panel IP is basically a flat plate as shown in FIGS. 2 and 3, but corresponds to the central portion of the electrode plate 2 in the four capacitive sensors S. A protrusion t is provided at a position where The protrusion t is for efficiently elastically deforming the electrode plate 2 by the load from the occupant and for linearizing the relationship between the pressing force due to the occupant weight and the voltage output.
Considering the reproducibility of the sensor, the position of the insert panel IP in plan view is constrained so that the protrusion t is in contact with the center of the electrode plate 2. Further, the protrusion t may be formed by using the head of the rivet RV as shown in FIG. [Pat P and Decorative Cover C] Since the pat P and the decorative cover C have been conventionally used that do not affect the present invention, description thereof will be omitted. [About the function of this vehicle occupant's weight detection system]
Since this vehicle occupant weight detection system is configured as described above, when the occupant sits on the seat portion Z of the seat, the occupant's weight can be instantly measured and the occupant's center of gravity position can be detected to some extent. That is, it is possible to detect whether the occupant is an adult or a child, and it is also possible to detect whether the occupant is in a position in which the center of gravity is positioned in the front or in which the occupant is leaning against the seat.

Further, in the electrostatic capacitance sensor S, the variable electrostatic capacitance portion C1 has a low cost because of its configuration, and the fixed electrostatic capacitance portion C2, the fixed resistors R1 and R2, the EX-OR logic IC [RIC]. ] Is a commercially available product and is inexpensive, so that the weight detection system as a whole is very inexpensive.

Further, in the above-mentioned weight detection system, since only the above-mentioned four capacitive sensors S having a simple structure and the insert panel IP are added to the seat portion Z of the conventional seat, the weight detecting system is mounted. Is very easy. [Other Embodiments] The circuit of FIG. 9 can be adopted instead of the circuit of the capacitance type sensor of FIG. In the circuit of FIG. 9, the phase-shifted square wave or sine wave input clock CLI is input to the time constant circuits T1 and T2. The operation principle is almost the same as that of FIG.

In the above embodiment, another type of load sensor can be adopted instead of the capacitance type sensor.

[0016]

Since the present invention has the above-mentioned structure, it has the following effects.

As is clear from the description of the embodiment of the invention, it is possible to provide a vehicle occupant weight detection system for detecting the weight of an occupant with high accuracy, and the weight and center of gravity position of the occupant with high accuracy. A vehicle occupant weight detection system for detecting could be provided.

[Brief description of drawings]

FIG. 1 is a perspective view of a seat of an automobile to which an automobile occupant weight detection system of the present invention is added.

FIG. 2 is an exploded perspective view of a main part of the weight detection system.

FIG. 3 is an enlarged cross-sectional view of a variable capacitance section of the weight detection system.

FIG. 4 is a circuit diagram of a capacitance type sensor of the weight detection system.

FIG. 5 is an enlarged cross-sectional view of a state in which an occupant weight acts on a seat portion of the seat.

FIG. 6 is an explanatory diagram showing a relationship between an input clock and an output clock when the electrostatic capacitance type sensor is used.

FIG. 7 is a block diagram of a circuit that adds the output from the capacitance type sensor by a so-called microcomputer.

FIG. 8 is a cross-sectional view of a variable capacitance section according to another embodiment.

FIG. 9 is a circuit diagram of a capacitive sensor according to another embodiment.

[Explanation of symbols]

Z seat IP Insert Ponnel S Capacitive sensor R1 fixed resistance R2 fixed resistance C1 Variable capacitance section C2 fixed capacitance section T1 time constant circuit T2 time constant circuit RIC EX-OR logic IC (exclusive OR circuit) CLI input clock CLO output clock

─────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-5-139233 (JP, A) JP-A-10-297334 (JP, A) JP-A-10-141992 (JP, A) International Publication 98/025112 (WO, A1) International Publication 98/029719 (WO, A1) (58) Fields investigated (Int.Cl. ⁷ , DB name) G01G 19/52 G01G 19/12 G01D 5/24

Claims (3)

(57) [Claims] 1. A seat for a passenger seat of an automobile
In a weight detection system for a vehicle occupant, two or more capacitive sensors for load detection are arranged with a displacement in the front-back direction so that the weight of the occupant and the center of gravity of the occupant when seated can be detected. The variable capacitance section that constitutes the capacitive sensor is formed by providing a gap between upper and lower electrodes, and a common insert having a projection protruding downward above the variable capacitance section. A panel is arranged, and the projection restrains the position of the insert panel in plan view so as to correspond to the central portion of the upper steel plate electrode plate that constitutes the variable capacitance portion. Car occupant weight detection system. 2. An electrostatic capacitance type sensor has two time constant circuits each of which has a variable resistance and a fixed electrostatic capacitance unit respectively combined with a fixed resistance, and outputs from these both time constant circuits are input to a logic IC. In addition, a square wave or sine wave input clock synchronized with both time constant circuits is input, and the time constant of the time constant circuit changes with the change in the capacitance of the variable capacitance section due to the occupant weight. In response to the,
2. The vehicle occupant weight detection system according to claim 1, wherein the duty% of the output clock of the logic IC is changed. 3. An electrostatic capacitance type sensor has two time constant circuits each of which has a variable resistance and a fixed electrostatic capacity unit combined with a fixed resistance, and outputs from the both time constant circuits are input to a logic IC. Furthermore, it is assumed that a phase-shifted square wave or sine wave input clock is input to each time constant circuit, and the time constant of the time constant circuit changes with the capacitance of the variable capacitance section due to the occupant weight. 2. The weight detection system for a vehicle occupant according to claim 1, wherein the duty% of the output clock of the logic IC is changed in accordance with the change of.