JP2001074541A - Seating occupant detecting device and seating occupant detecting method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent a classification from frequency changing in a seating occupant detecting device and a seating occupant detecting method for performing the classification according to a physique of a seating occupant. SOLUTION: A heavy class is determined when a detected weight W becomes not less than a first threshold TH1, and determination of the heavy class is kept until the detected weight W becomes less than a second threshold TH2 (<TH1). After the detected weight W becomes less than the second threshold TH2 to determine a light class, the determination of the light class is kept until the detected weight W becomes not less than the first threshold TH1. Instead of the detected weight W at each time point, an average value of the detected weights W over a predetermined period may be used. The classification may be performed based on a ratio of a period when the detected weights W are not less than the first threshold TH1 in the predetermined period.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a seated occupant detection device and a seated occupant detection method, and more particularly to a seated occupant detection device and a seated occupant detection method for classifying seated occupants based on a load acting on a seat surface. About.

[0002]

2. Description of the Related Art Conventionally, for example, Japanese Patent Application Laid-Open No.
An occupant detection device for controlling the operation / non-operation of an airbag device is known as disclosed in Japanese Patent Application Publication No. JP-A-2004-115139. This occupant detection device includes a load detection unit attached between a vehicle seat and a vehicle floor. The load detecting means outputs a signal corresponding to the load acting on the seat surface to the control device. The control device determines that the occupant is not seated when the load detected based on the output signal of the load detecting means does not reach the predetermined threshold, and prohibits the operation of the airbag.

[0003]

However, the load acting on the seat surface fluctuates every moment according to a change in the posture of the occupant, a running vibration of the vehicle, and the like. Therefore, when an occupant having a weight near the threshold value is seated, the load value detected by the load detecting means may fluctuate around the threshold value. In this case, if the operation permission / prohibition state of the airbag is displayed by an indicator (for example, a warning light), the display of the indicator is frequently switched, thereby giving the occupant anxiety about the system operation state.

SUMMARY OF THE INVENTION The present invention has been made in view of the above points, and in a seated occupant detection apparatus and method for classifying occupants based on a load acting on a seat surface of a seat, the classification result is frequently obtained. The purpose is to prevent fluctuations.

[0005]

The above object is achieved by the present invention.
And a load detecting means for detecting a load acting on the seat surface of the vehicle seat, and at least two of the load detecting means.
And a occupant classification device for classifying the occupant into at least two classes based on the detected values at two time points.

Further, the above object is achieved by a load detecting step for detecting a load acting on a seat surface of a vehicle seat, and detecting values at at least two time points detected in the load detecting step. On the basis of the,
An occupant classification step of classifying the occupant into at least two classes.

[0007] In the inventions described in claims 1 and 17, the seated occupants are classified based on the detected values of the load acting on the seating surface at at least two times. For this reason, the classification of the seated occupant is not immediately changed by the detected value at one time, so that frequent change of the classification is prevented. Further, the above object is achieved by a load detecting means for detecting a load acting on a seat surface of a vehicle seat and a magnitude relationship between a detection value of the load detecting means and a threshold value. The occupant class that classifies the seated occupant based on the occupant class and maintains the classification until the magnitude relationship between the detection value of the load detection unit and another threshold value different from the one threshold value changes. And a dividing means.

The above object is achieved by a load detecting step for detecting a load acting on a seating surface of a vehicle seat, and a load detecting step for detecting a load acting on the seat surface of the vehicle seat. While classifying the seated occupants based on the magnitude relationship, the classification is thereafter maintained until the magnitude relationship between the detected value of the load detection means and another threshold value different from the one threshold value changes. And an occupant classification step.

In the invention according to claims 2 and 18, after the seated occupants are classified based on the magnitude relationship between the detected value of the load acting on the seat surface and the one threshold value, the load detected value and other values are determined. The classification is maintained until the magnitude relationship with the threshold value changes. Therefore, if only the magnitude relationship between the load detection value and the one threshold value changes, the classification is not changed, so that frequent changes in the classification are prevented.

Further, as described in claim 3, claim 1
In the seated occupant detection device described above, the occupant classification means measures an average value of the detection values of the load detecting means during a predetermined period, and determines the occupant occupant based on a magnitude relationship between the average value and a threshold value. And the classification is maintained until the magnitude relationship between the average value of the detection values of the load detection means and another threshold value different from the one threshold value in a predetermined period thereafter changes. It may be that.

According to the third aspect of the present invention, the occupant classification means performs the classification using an average value of the detection values of the load detection means during a predetermined period. For this reason, the classification result is less likely to be affected by a change in the detection value of the load detection means, and frequent changes in classification are effectively prevented. According to a fourth aspect of the present invention, in the seated occupant detection device according to the second aspect, the occupant classifying unit is configured to determine a ratio of a time during which a detected value of the load detection unit is equal to or greater than a predetermined threshold during a predetermined period. The seated occupants may be classified based on

In the invention according to claim 4, the occupant classifying means classifies the occupants based on a ratio of a time when a detected value of the load detecting means is equal to or more than a predetermined threshold value in a predetermined period. For this reason, the classification result is less likely to be affected by a change in the detection value of the load detection means, and frequent changes in classification are effectively prevented.

Further, as described in claim 5, claim 4
In the seated occupant detection device described above, the occupant classification means performs classification based on a magnitude relationship between the time ratio and one predetermined value, and thereafter, the time ratio and the one predetermined value. The classification may be maintained until the magnitude relationship with another different predetermined value changes.

[0015] In the invention described in claim 5, the occupant classifying means is based on a magnitude relation between a ratio of a time when a detected value of the load detecting means is equal to or more than a predetermined threshold value in a predetermined period and one threshold value. After classifying seated occupants,
The classification is maintained until the magnitude relationship between this time ratio and another threshold value changes. Therefore, the classification is not changed only by changing the magnitude relation between the time ratio and the one threshold value, so that the frequent change in the classification is more effectively prevented.

In addition, as described in claim 6, claim 1
6. The seat occupant detection device according to claim 1, wherein the load detection unit is capable of detecting a load acting on a front portion and a rear portion of the seat surface, respectively, and before and after the load acting on the seat surface. Classification correction means for correcting the classification by the classification means based on the distribution may be provided.

In the invention according to claim 6, the classifying correction means corrects the classifying of the seated occupant based on the front-rear distribution of the load acting on the seat surface. For this reason, for example, when the seating position of the occupant moves back and forth, appropriate classification is performed according to the seating position. In this case, as described in claim 7, in the seated occupant detection device according to claim 6, the occupant classifying correction unit is configured such that the load acting on the front portion of the seat surface is the load acting on the rear portion of the seat surface. If the class is larger than a predetermined degree, the classification by the classifying means may be modified to a lighter class.

In the invention according to claim 7, when the load acting on the front portion of the seat surface is greater than the load acting on the rear portion of the seat surface beyond a predetermined degree, the occupant may move to the front portion of the seat. You can judge that you are sitting. Therefore, in such a case, the classification is changed to the class on the lighter side, whereby appropriate classification according to the seating position is performed.

Further, as described in claim 8, claim 6
The seated occupant detection device according to the above, further comprising deceleration detection means for detecting a vehicle deceleration, the classification correction means,
If the vehicle deceleration exceeds a predetermined value and the decreasing gradient of the load acting on the rear portion of the seat surface exceeds a predetermined value, the classification by the occupant classification means may be modified to a lighter side class. Good.

According to the eighth aspect of the present invention, when the vehicle deceleration exceeds a predetermined value and the load acting on the rear portion of the seat decreases at a gradient equal to or higher than the predetermined value, the rear end of the seated occupant is seated by the sudden braking. It can be determined that the vehicle is slightly floating from the seat surface, and the forward movement of the occupant can be predicted. In such a case, the classification of the seated occupant is corrected to the class on the light side, whereby the classification according to the change in the seating position is performed quickly and appropriately.

Also, as described in claim 9, claim 1 is
The seat occupant detection device according to any one of claims 1 to 5, wherein the load detecting means can detect loads acting on a front portion and a rear portion of a seat seat surface, respectively, and the occupant classifying means comprises: When the ratio of the load acting on the front part and the rear part of the surface changes at a gradient equal to or more than a predetermined value, the classification may be invalidated and a new classification may be performed.

In the ninth aspect of the present invention, when the front-rear distribution of the load acting on the seat changes at a gradient equal to or greater than a predetermined value, it can be determined that the seating position of the occupant has moved back and forth. In such a case, appropriate classification can be performed according to the seating position of the occupant by invalidating the previous classification and performing new classification. Further, as described in claim 10, any one of claims 1 to 9
The seated occupant detection device according to the above, further comprising acceleration detection means for outputting acceleration in at least one direction in the vehicle longitudinal direction and vertical direction, the occupant classifying means, the acceleration in at least one direction in the vehicle longitudinal direction and vertical direction. If it exceeds a predetermined value, the value detected by the load detecting means may be ignored.

According to a tenth aspect of the present invention, when the acceleration in at least one of the longitudinal direction and the vertical direction of the vehicle exceeds a predetermined value, the load detected by the load detecting means is:
It is considered that the weight of the seated occupant is not correctly reflected.
In such a case, the occupant classification means ignores the detection value of the load detection means, thereby preventing improper classification based on the incorrect detection value.

The above object is achieved by a load detecting means for detecting a load acting on a seat surface of a vehicle seat, and at least a seated occupant being detected based on a detected value of the load detecting means. Occupant classifying means for classifying into two classes, wherein the occupant classifying means comprises:
When the classification of the seated occupants is performed under the predetermined condition, this is achieved by a seated occupant detection device that fixes the classification thereafter.

Further, the above object is achieved by a load detecting step for detecting a load acting on a seat surface of a vehicle seat, and at least a seated occupant is determined based on a detected value in the load detecting step. An occupant classifying step of classifying the occupants into two classes, and in the occupant classifying step, when the classifying of the seated occupants is performed under a predetermined condition, the occupant occupant detecting method for fixing the classifying thereafter. Achieved.

In the invention according to claims 11 and 22,
When the classification of the seated occupant is performed under the predetermined condition, the classification is fixed thereafter. Therefore, frequent classification is prevented. Generally, the detection value of the load detection means cannot exceed the weight of the occupant. That is,
It can be said that the larger the detected value of the load detecting means, the closer the detected value is to the weight of the occupant. For this reason, as described in claim 12, in the seated occupant detection device according to claim 11,
The occupant classification means may fix the classification at the time when the detected value of the load detection means becomes equal to or greater than a predetermined threshold value.

In general, it is considered that an occupant sits deeply in a seat when wearing a seat belt. In such a seated state, most of the weight acts on the seat surface, so that it can be determined that the detected value of the load detecting means accurately reflects the weight of the occupant. Therefore, as described in claim 13, in the seated occupant detection device according to claim 11, the occupant classification means may be fixed to the classification at the time when the seat belt is fastened.

In general, it is considered that the driver sits deeply in the seat when turning on the ignition switch while wearing the seat belt. In such a seated state, most of the weight acts on the seat surface, so that it can be determined that the detected value of the load detecting means accurately reflects the weight of the occupant. Therefore, as described in claim 14, in the seated occupant detection device according to claim 11, the occupant classifying means determines whether or not the ignition switch is turned on in a state in which the seat belt is worn on the driver's seat side seat. It is good also as fixing to the classification in.

According to a fifteenth aspect of the present invention, in the seated occupant detection device according to any one of the first to fourteenth aspects, the seat belt is in the ALR state, and the detected value of the load detecting means is A CRS mounting determination unit that determines that the child restraint device is mounted when the value is equal to or less than the predetermined value may be provided. In the invention according to claim 15, when the seat belt is in the ALR state, it can be determined that the child restraint device is worn on the seat or an occupant of an extremely large size is seated. Therefore, when the seat belt is in the ALR state and the detection value of the load detection means is equal to or less than the predetermined value, it can be determined that the child restraint device is worn.

[0029] In this case, the child restraint system may be continuously mounted on the vehicle for a long time. In such a case, it is meaningless to determine whether or not the child restraint device has been removed while the ignition switch is off,
In addition, extra power is consumed to operate the load detecting means. Then, as described in claim 16,
16. The seat occupant detection device according to claim 15, wherein the CR
When the child restraint device is determined to be mounted by the S mounting determination means and the ignition switch is turned off, a sensor pause means for suspending the operation of the load detection means is provided. Power consumption can be reduced.

[0030]

FIG. 1 is a sectional view of a system according to an embodiment of the present invention, taken along a plane passing through the center of a passenger seat in a vehicle width direction. In FIG. 1, an occupant 11 seated deeply in the vehicle seat 10 of the passenger seat is indicated by a two-dot chain line, and an occupant 11 'seated forward on the vehicle seat 10 is indicated by a solid line.

As shown in FIG. 1, the system of this embodiment is
An airbag controller 12 is provided. An airbag module 14 and an indicator 16 are connected to the airbag controller 12. The airbag module 14 and the indicator 16 are provided on an instrument panel 18 of the vehicle. The airbag module 14 operates by receiving a predetermined operation signal from the airbag controller 12. The indicator 16 is turned on when a predetermined lighting signal is supplied from the airbag controller 12. The airbag controller 12 turns on the indicator 16 when the operation of the airbag module 14 is prohibited.

An acceleration sensor 20 is connected to the airbag controller 12. The acceleration sensor 20 is provided at the center of the passenger compartment floor in the vehicle width direction, and outputs signals corresponding to the acceleration in the vehicle front-rear direction and the vertical direction to the airbag controller 12. The airbag controller 12 detects the vehicle longitudinal and vertical acceleration based on the output signal of the acceleration sensor 20.

The seat belt buckle 21 is connected to a seat belt wearing sensor 22 and an ALR sensor 24. The seat belt wearing sensor 22 and the ALR sensor 24 are connected to a seat sensor controller 26. The seat belt wearing sensor 22 outputs a predetermined belt wearing signal to the seat sensor controller 26 when the seat belt is worn. The ALR sensor 24 outputs a predetermined ALR signal to the seat sensor controller 26 when the seat belt is once completely pulled out (ALR state). The seat sensor controller 26 includes the seat belt wearing sensor 22.
Then, based on the output signal of the ALR sensor 24, it is determined whether the seat belt is worn or not and whether or not the seat belt is in the ALR state. The sheet sensor controller 26
Is connected to the airbag controller 12 described above.

FIG. 2 is a perspective view of the vehicle seat 10.
As shown in FIG. 2, the vehicle seat 10 includes two upper seat rails 30 and 32 extending on both sides thereof in parallel with each other in the vehicle traveling direction. Upper seat rail 30,
32 is a lower seat rail 3 fixed to the cabin floor.
The guides 4 and 36 are provided so as to be movable in the vehicle front-rear direction.

The upper seat rails 30, 32 are connected to each other by beams 38, 40 extending parallel to each other in the vehicle width direction. Beams 38, 40 are located in the center
Small section 38 having a smaller section modulus than other parts
a and 40a. Small cross section 38a, 4
Strain sensors 42 and 44 are mounted on the lower surface of Oa, respectively. The strain sensors 42 and 44 are connected to the sheet sensor controller 26,
a, an electrical signal corresponding to the distortion generated at 40a is output to the sheet sensor controller 26. The sheet sensor controller 26 detects the distortion of the small cross sections 38a, 40a based on the output signals of the distortion sensors 42, 44.

A seat pan 48 is provided above the beams 38 and 40. The seat pan 48 has a small section 3
It is fixed to the beams 38 and 40 by bolts 49 and 50 at positions symmetrical to each other with respect to 8a and 40a. A seat cushion (not shown) is provided on the upper surface of the seat pan 48. Also, upper seat rail 3
The seat back 52 is located at the rear end of the vehicle 0, 32 in the vehicle traveling direction.
Are rotatably connected around a shaft 54.

According to the above configuration, the occupant is seated on the vehicle seat 1.
When seated at zero, the load is transmitted to the beams 38, 40 via the seat cushion and seat pan 48. Each of the beams 38 and 40 bends according to the load transmitted from the seat pan 48, that is, according to the load of the seated occupant at the front and rear portions of the seat surface.
Then, distortion occurs in the small cross-sections 38a, 40a of the beams 38, 40 in accordance with the bending of each beam. Therefore, the seat sensor controller 26 can detect the load acting on the front and rear portions of the seat surface based on the strain of the small cross-sections 38a and 40a detected from the output signals of the strain sensors 42 and 44. .

In this embodiment, the seat sensor controller 26 determines the presence or absence of a seated occupant based on the load acting on the seat surface, and classifies the seated occupant according to its weight in a weight class (for example, an adult) and a light weight. Classification is made into two classes of classes (for example, children). When there is no seated occupant, and when the seated occupant is of a lightweight class, the airbag controller 12 transmits an airbag operation prohibition signal to the airbag controller 12 to prohibit the operation of the airbag module 14, and If the weight class is the weight class, the operation of the airbag module 14 is permitted by transmitting an airbag operation permission signal to the airbag controller 12.

As a method of classifying the seated occupants according to their weights, when the load acting on the seat surface exceeds a predetermined threshold value, it is conceivable to judge that the class is the weight class. However, in this method, when an occupant having a weight near the threshold is seated, the operation permission / non-permission state of the airbag module 14 frequently changes due to a change in the sitting posture, the running vibration of the vehicle, and the like. There is. In this case, as described with respect to the above-described related art, the indicator 16 frequently flashes to give the occupant a feeling of anxiety.

On the other hand, the system of the present embodiment can prevent frequent changes in the permission / non-permission of the operation of the airbag module 14, that is, prevent the classification result of the seated occupant from changing frequently. It is characterized by points. In this embodiment, the sheet sensor controller 26, the first threshold value TH _1, holds a second threshold value TH _2, and the third threshold value _{TH 3 (TH 1> TH 2} > T
H _3). Then, the sum of the load acting on the front and rear of the seating surface (hereinafter, the detection referred to as weight value W) is the third threshold value TH ₃ (e.g., 15 kgf) is less than, the passenger does not sit Judge. On the other hand, when the detected weight value W is the third threshold value TH ₃ or more, the first threshold value TH ₁
(For example, 45 kgf) and the second threshold value TH ₂ (for example, 35 kgf), it is determined whether the seated occupant is of the weight class or the lightweight class.

FIG. 3 is a diagram for explaining a method of classifying a seated occupant into a weight class or a lightweight class in the present embodiment. The horizontal axis represents time, and the vertical axis represents the detected weight value W at each time point. Is shown. In FIG. 3, the detected weight value W fluctuates with time due to a change in sitting posture, running vibration of the vehicle, and the like. In the period I shown in FIG. 3, the detected weight value W is the first
It fluctuates in the vicinity of the threshold value TH _1. Thus, for example, than were classified based on the magnitude relationship between the first threshold value TH ₁ and the detected weight value W, the result of the classification will vary frequently. On the other hand, in the present embodiment, the classification is performed by the following method, thereby preventing the classification result from frequently changing.

[0042] In this embodiment, first, for example sensed weight value W at the time the ignition switch is turned on is determined to weight class if the first threshold value TH ₁ or more, the first threshold value TH ₁ If it is less than, it is determined to be a lightweight class. If the seated occupant is determined to be a weight class detected weight value W is to below a second threshold value TH _2, the determination is maintained. Then, when the detected weight value W falls below the second threshold value (time t ₁ shown in FIG. 3), for example, the load on the floor due to the occupant 11 ′ being in a forward position as shown by a solid line in FIG. It is determined that the distribution has increased. In this case, the seated occupant is approaching the airbag module 14, and it is determined that it is not preferable to operate the airbag module 14 even in the heavy class (adult), and the classification is changed to the lightweight class. .

Similarly, when the ignition class is determined to be the light weight class when the ignition is turned on, and when the classification is changed from the heavy weight class to the light weight class as described above, the average value of the detected weight values W is then changed to the second class. until first threshold TH ₁ or more, the determination of weight classes is maintained. Then, when the detected weight value W has reached the first threshold value TH _1, classification is changed to a weight class. That is, when the detected weight value W reaches the first threshold value (time t ₂ shown in FIG. 3) after the determination of the light weight class, the occupant 11 ′ in the forward posture shown in FIG. Is determined to have returned to the posture 11, and the classification is changed to the weight class in order to permit the operation of the airbag module 14.

As described above, in this embodiment, the detected weight value W is lower than the second threshold value TH ₂ when the weight class is determined, and the detected weight value W is determined when the weight class is determined. There until the first threshold value TH ₁ or more, respectively, the current class is maintained. For this reason, the detected weight value W is determined by a change in the sitting posture of the seated
Does not frequently change. Therefore, according to the present embodiment, it is possible to prevent the lighting / extinguishing of the indicator 16 from being frequently switched, thereby avoiding giving the occupant a feeling of anxiety about the system.

Next, a second embodiment of the present invention will be described. The system of the present embodiment differs from the system of the first embodiment only in the method of classifying the weight class and the lightweight class. In the present embodiment, the first threshold value TH
Classification of weight class and lightweight class is performed using only ₁ . Incidentally, the point to determine the presence or absence of a seated occupant based on the size relationship between the third threshold value TH ₃ and the detected weight value W is
This is the same as the first embodiment.

FIG. 4 shows a seated occupant in this embodiment.
Classify into weight class or lightweight class according to weight
FIG. 5 is a diagram for explaining a method of performing the above-mentioned operations, in which the horizontal axis represents time, and the vertical axis represents time.
Indicates the detected weight value W at each time point. In this embodiment
As in the case of the first embodiment, first, for example,
Detected weight value W at the time when the NISCHON switch is turned on
Is the first threshold TH₁If the weight class is
And the first threshold value TH₁If less than
Is determined. Thereafter, as shown in FIG.
Judgment period T₁, T_Two, T_Three, T_Four, ..., each size
Within a fixed period, the detected weight value W is equal to the first threshold value TH. ₁Above
Sum S for a certain time_HAnd the detected weight value W is the first threshold value T
H₁Sum S of times less than_LAnd ask. And now
If the current classification is the weight class, each judgment period
The detected weight value W is within the first threshold value TH₁Is less than
Sum S between_LRatio R_L(= S_L/ (S_H+ S_L))But
Predetermined value R larger than 0.5₀(Eg 0.7)
(That is, the detected weight value W is equal to the first threshold value TH).₁Less than
Sum S of the time above_HRatio R_H(= S_H/ (S_H+
S_L)) Is (1-R₀A) weight class until
The judgment is maintained. And the ratio R_LIs the predetermined value R₀Reached
Then, because the occupant was leaning forward,
It is determined that the load distribution has increased. In this case, the weight class
Airbag module 14 even if you are an adult
It is judged that it is not desirable to make it, and the classification is lightweight
Changed to class. In FIG. 4, the determination period T_Threesmell
And the ratio R_LIs the predetermined value R₀As described above, the determination period T3
End time t_ThreeSince then, the classification has been changed to a lightweight class
Have been.

[0047] Similarly, if the determination current classification is lightweight class, the ratio R _H of the sum S _H time detected weight value W is the first threshold value TH ₁ or more in each determination period given Until the value _R0 or more (that is, the ratio _RL is (1-R
₀ ) The determination of the lightweight class is maintained until it is less than or equal to).
Then, when the ratio _RH reaches the predetermined value _R0 , the classification determination is changed to the weight class. That is, when the ratio _RH reaches the predetermined value _R0 after the determination as the lightweight class, the occupant 11 'who is seated forward is in the normal sitting posture 1
It is determined that the value has returned to 1, and the classification is changed to the weight class in order to permit the operation of the airbag module 14.

As described above, in the present embodiment, in each determination period,
Detected weight value W and first threshold value TH ₁Biased relationship with
The other class from the current class (that is, the current class
If the weight is the weight class, the detected weight value W is the first threshold
TH₁On the side that is less than
The detected weight value W is equal to the first threshold value TH.₁Above
Until it changes, the current class decision is maintained
You. For this reason, changes in the vibration of the vehicle and the sitting posture of the seated occupant
Classification even when the detected weight value W fluctuates due to factors such as
The results do not change frequently. Therefore, in this embodiment,
According to this, the indicator 16 is frequently switched on and off.
To prevent occupants from interacting with the system.
It is possible to avoid giving a sense of anxiety.

When the detected weight value W is obtained at a predetermined sampling interval, the ratios R _H and R _L are
Respectively sensed weight value W is the frequency at the first threshold value TH ₁ or more, and the detection weight value W is determined based on the frequency which is the first less than the threshold value TH _1. Also in the first embodiment, the average value W _av detected weight value W in each determination period to provide a determination period given as in the second embodiment the length, the average value W _av second It determines that lightweight class when it falls below a threshold value TH _2, may be determined as the weight class if the average value W _av becomes the first threshold value TH ₁ or more.

In the first and second embodiments,
Although the seated occupant is classified into two classes, a weight class and a lightweight class, the occupant may be classified into three or more classes. For example, by providing a fourth threshold value TH ₄ (for example, 70 kgf) larger than the first threshold value TH _1, it is possible to classify the vehicle into three classes: a maximum weight class, a weight class, and a lightweight class. . In this case, for example, in the first embodiment, the detected weight value W is TH ₄
It determines that the heaviest class when it becomes equal to or greater than, then, sensed weight value W may be changed to classification into weight classes when it falls below the first threshold value TH _1. In addition, the second
In the embodiment, the detected weight value W is equal to the fourth
When the ratio of the threshold TH ₄ or more in which time is a predetermined value R ₀ or more, determines that the heaviest class, then the percentage of time detected weight value W is the fourth less than the threshold value TH ₄ When the value becomes equal to or more than the predetermined value _R0 , the classification may be changed to the weight class.

In the first and second embodiments, even when the seated occupant is determined to be of the weight class (adult), the occupant moves the seating position forward and the detected weight value W decreases thereafter. In this case, the classification determination is changed to the lightweight class, and the operation of the airbag module 14 is prohibited.
However, when an adult is seated, it is desirable to permit the operation of the airbag module 14 with as high a probability as possible. From this point of view, for example, the if it is determined that the lightweight class in the first embodiment, a smaller value of the first threshold value TH ₁ for changing the determination to weight classes, a lightweight class to weight class May be easily changed. Also, in the second embodiment, for example, by changing the length of the determination period during the determination as the lightweight class, the change from the lightweight class to the weight class is performed in a short period of time, or Predetermined value R when changing from light weight class to heavy weight class
_{By making 0} smaller than the predetermined value R ₀ when changing from the weight class to the light weight class, the class change from the light weight class to the heavy weight class may easily occur.

As described above, the occupant 11 'shown in FIG.
When the user sits on the vehicle seat 10 at the front and approaches the airbag module 14 as described above, it is desirable to prohibit the operation of the airbag module 14. On the other hand, the sensor seat controller 26 can detect the load acting on the front and rear portions of the seat, that is, the front and rear distribution of the detected weight value W. Therefore, in the first and second embodiments, when the distribution before and after the detected weight value W changes at a gradient exceeding a predetermined value, the classification determination up to that point is cleared, and the same as when the ignition is turned on. Classification may be performed again based on the detected weight value W at that time.

[0053] according according to the method, for example, relatively lightweight adult (i.e., body weight adults as close to the first threshold value TH ₁₎ when the varying sitting posture front portion is detected weight value W is a first threshold value TH _1, less than real by being determined to lightweight class at that time, can be quickly prohibited operation of the air bag module 14. Moreover, in this way lightweight adults returning from the seating posture of the front portion in the normal sitting posture, the detection weight value W becomes the first threshold value TH ₁ or more, it is determined that real weight class at that time Thereby, the operation of the airbag module 14 can be promptly permitted. In this way, when the front-rear distribution of the detected weight value suddenly changes beyond a predetermined gradient, the classification is performed again based on the detected weight value W at that time, so that the classification can be performed quickly and according to the sitting posture of the occupant. Appropriate classification determination can be performed.

When a large occupant is seated,
Even when the seating position is at the front end of the seat, the detected weight value W is large. In this case, in the methods described in the first and second embodiments, there is a case where the operation is determined to be the weight class and the operation of the airbag module 14 is permitted. Therefore,
When the distribution of the detected weight value W to the front of the seat is larger than a predetermined degree with respect to the distribution to the rear of the seat (for example,
(For example, when the front allocation is larger than the rear allocation, when the value obtained by subtracting the rear allocation from the front allocation exceeds a predetermined value, or when the ratio of the front allocation to the rear allocation exceeds the predetermined value)
It is preferable to determine that the class is a light weight class (in the case of classifying into three or more classes, the determined class is changed to a lower weight side).

When the vehicle is running on a rough road or braking suddenly, the vertical acceleration or the longitudinal acceleration that occurs in the vehicle increases, so that it is difficult to obtain the detected weight value W that appropriately reflects the weight of the occupant. Becomes Therefore, the first and second
In the embodiment, if the acceleration in the up-down direction or the back-and-forth direction detected based on the output signal of the acceleration sensor 20 exceeds a predetermined value, the detected weight value W during that time is ignored and the immediately preceding classification determination is maintained. Is preferred.

When a sudden braking operation is performed, the seated occupant may move forward with a large deceleration. When the seated occupant moves forward, the rear portion of the detected weight value W decreases at a large gradient because the buttocks of the occupant tend to float from the seat surface prior to the movement. Therefore, in the first and second embodiments,
If the vehicle deceleration detected based on the output signal of the acceleration sensor 20 exceeds a predetermined value and the decreasing gradient of the rear distribution of the detected weight value W exceeds a predetermined value, it is determined that the vehicle is a lightweight class (3 class). In the case of classifying as described above, it is preferable to lower the determined class to the lower weight side). In this case, since the forward movement of the seated occupant can be predicted at an early stage, the classification can be performed more quickly and appropriately.

In the first and second embodiments, the operation of the airbag module 14 is permitted only when it is determined that the seated occupant is of the weight class, and when the seated occupant is of the light weight class and there is no seated occupant. In this case, the operation of the airbag module 14 is prohibited. However,
When an airbag that can be operated with two levels of inflation output is used as the airbag module 14, the inflation output of the airbag module 14 may be changed according to the determined class. That is, the operation with a high expansion output may be permitted for the heavy class, and the operation with a low expansion output may be permitted for the light class. When the airbag module 14 can operate with three or more stages of inflation output, as described above, the classification of the seated occupant is also performed in three or more stages, and a class having a large weight is determined according to the determined class. The operation at a higher expansion output may be permitted.

In the first and second embodiments, when the operation of the airbag module 14 is prohibited,
By illuminating the indicator 16, the occupant is notified of the fact. However, it is meaningless to turn on the indicator 16 when there is no occupant in the passenger seat. Therefore, if the seated occupant is not present (i.e., when the detected weight value W is less than the third threshold value TH ₃₎ it may be possible to turn off the indicator 16.

In the first and second embodiments, the sheet sensor controller 26 has the strain sensors 42, 4
The sheet sensor controller 26 detects the load detection value W based on the output signal of Step 4 in the load detection means and load detection step described in the claims by the method described with reference to FIGS. 3 and 4. In the occupant classification means and the occupant classification step described in the claims, the classifying of the occupant is performed by the seat sensor controller 26 such that the front distribution of the detected weight value W exceeds a predetermined degree with respect to the rear distribution. If the deceleration of the vehicle exceeds a predetermined value and the decreasing gradient of the rear distribution of the detected weight value W exceeds a predetermined value, it is determined that the vehicle is a lightweight class. And in the classifying correction step, the seat sensor controller 28 calculates the acceleration in the vehicle longitudinal direction and the vertical direction based on the output signal of the acceleration sensor 20. Acceleration detecting means for detecting is claimed, the sheet sensor controller 2
The detection of the vehicle deceleration by the reference numeral 8 based on the output signal of the acceleration sensor 20 corresponds to the deceleration detecting means described in the claims.

Next, a third embodiment of the present invention will be described. In this embodiment, when the detected weight value W exceeds a predetermined value, the classification of the seated occupant is performed, and thereafter, the detected weight value W
Irrespective of the change in, the classification is prevented from changing frequently. The system according to the present embodiment is realized by the sheet sensor controller 26 executing the routine shown in FIG. 5 in the configuration shown in FIGS. The routine shown in FIG. 5 is a routine that is repeatedly started each time one processing cycle ends. When the routine shown in FIG. 5 is started, first, the process of step 100 is executed.

In step 100, an airbag operation prohibition signal is transmitted to the airbag controller 12. When receiving the airbag operation prohibition signal, the airbag controller 12 prohibits the operation of the airbag module 14. That is, in this routine, the classification of the seated occupants is initialized to the lightweight class. Step 102
Then, it is determined whether or not the ignition key of the vehicle is on. As a result, if the ignition key is not on, the current routine ends. on the other hand,
If it is determined in step 102 that the ignition key is on, the process of step 104 is performed.

In step 104, it is determined whether or not the detected weight value W is equal to or greater than a predetermined threshold value C ₁ (for example, 35 kgf). Note that the detected weight value W in the present embodiment and a fourth embodiment described later is, for example, a low-pass filter process or a predetermined time (for example, 1 This means a value obtained by performing a signal processing such as a time averaging process over seconds) to remove a vibration component caused by a vehicle vibration or the like. Also,
Threshold C ₁ is set to be the lower limit of the sensed weight value W when the adult is normally seated as passenger 11 shown in FIG. 1 (e.g., 35 kgf).

If it is determined in step 104 that W ≧ C ₁ is not established, the current routine ends. On the other hand, in step 104, if W ≧ C ₁ is satisfied, an adult is seated, i.e., the seated passenger is determined to be a weight class, the process of step 106 is performed.
In step 106, an airbag activation permission signal is transmitted to the airbag controller 12. When receiving the airbag operation permission signal, the airbag controller 12 permits the operation of the airbag module 14.

[0064] At step 108 subsequent to step 106, sensed weight value W is, whether the predetermined threshold value C ₂ or less is determined. Threshold C ₂ is set to be a child seat or the like CRS lower limit of the child's body weight can be seated alone without using (for children restraint system) (e.g., 15 kgf). Therefore, if W ≦ C ₂ is satisfied in step 108, it is determined that the occupant is not seated (that is, the occupant has exited). In this case, the determination of permission / non-permission of the operation of the airbag module 14, that is, it is determined that the classification of the seated occupants should be performed again, and the current routine ends. Step 10
In step 8, if W ≦ C ₂ is not satisfied, the process of step 106 is executed again, and the transmission of the airbag operation permission signal to the airbag controller 12 is continued.

[0065] As described above, according to the routine shown in FIG. 5, after the ignition key is turned on, when the detected weight value W exceeds the threshold C _1, should allow operation of the air bag module 14 That is, it is determined that the seated occupant is of the weight class (adult), and thereafter, the determination is not changed until the occupant gets off the vehicle. The detected weight value W is
The weight of the occupant may be smaller than the weight of the occupant due to a change in the seating posture of the occupant, for example, but the weight of the occupant cannot be exceeded. Therefore, once the detected weight value W exceeds the threshold value C ₁ , regardless of a change in the detected weight value W thereafter, the classification is not changed unless the occupant gets off the vehicle. The classification can be maintained, and the classification can be prevented from changing frequently.

Next, a fourth embodiment of the present invention will be described. In the present embodiment, when the detected weight value W at the time when the seat belt is fastened is equal to or less than the predetermined value, the classification determination is fixed to the lightweight class, thereby preventing the class determination from frequently changing. At the same time, it is further determined whether or not a CRS (child restraint device) is attached.

The system of this embodiment is the same as that shown in FIGS.
Is realized by the sheet sensor controller 26 executing the routine shown in FIG. 6 and FIG. The routine shown in FIGS. 6 and 7 is a routine that is repeatedly started each time one processing cycle ends. 6 and 7, steps for performing the same processing as in the routine shown in FIG. 5 are denoted by the same reference numerals, and description thereof will be omitted. In the routine shown in FIGS. 6 and 7,
If W ≧ C ₁ is not satisfied in step 104 shown in FIG. 6, the process of step 150 shown in FIG. 7 is executed next.

In step 150, it is determined whether or not the seatbelt has been fastened based on the output signal of the seatbelt fastening sensor 22 (that is, the seatbelt is not fastened from the previous processing cycle to the current processing cycle). Is changed to the mounted state). In general, when the occupant wears the seat belt, it is considered that the occupant takes a posture sitting deep in the seat, such as the occupant 11 shown by a two-dot chain line in FIG. Therefore, it can be determined that the detected weight value W at the time when the seat belt is fastened accurately reflects the weight of the occupant. Therefore, if W ≧ C ₁ is not satisfied in step 104 and it is determined in step 150 that the seatbelt is fastened, it is determined that the seated occupant is of the lightweight class, and then in step 152 The processing is executed. Step 15
At 0, when it is determined that the seatbelt wearing operation is not performed, it is determined that the detected weight value W may have decreased due to the occupant's sitting posture being closer to the front. After the determination, the current routine is terminated.

At step 152, an airbag operation prohibition signal is transmitted to the airbag controller 12. In the subsequent step 152 step 154, sensed weight value W is equal to or less than a predetermined value C ₂ is determined. As a result, if W ≦ C ₂ holds, it is determined that the seated occupant has exited, and the current routine ends. On the other hand, if W ≦ C ₂ is not satisfied in step 154, the process of step 152 is executed again, and the transmission of the airbag operation prohibition signal to the airbag controller 12 is continued.

If W ≦ C ₂ is not satisfied in step 108 shown in FIG. 6, the process of step 160 shown in FIG. 7 is executed. In step 160,
Based on the output signal of the ALR sensor 24, it is determined whether the seat belt is in the ALR state. As a result, A
If the state is not the LR state, the processing of step 106 shown in FIG. 6 is executed again, so that the transmission of the airbag operation permission signal is continued. On the other hand, in step 160, AL
If it is in the R state, the process of step 162 is executed next.

[0071] At step 162, sensed weight value W is equal to or the predetermined threshold value C ₃ or less is determined. The threshold value C ₃ is set to CR on the vehicle seat 10 by the seat belt.
When S is mounted, the load is set to a value (for example, 50 kgf) larger than the upper limit of the load acting on the seat surface. In general, it is considered that the seat belt enters the ALR state when the CRS is worn by the seat belt or when an occupant of an extremely large size sits. Therefore, the threshold value C ₃ at step 162 by setting as described above, W
When ≦ C ₃ holds, it can be determined that the CRS is mounted on the vehicle seat 10. In this case, in step 164, after the airbag operation prohibition signal is transmitted to the airbag controller 12, the current routine ends. On the other hand, in step 162, W ≦
If C ₃ is not satisfied, it is determined that the occupant of the very large physique seated, then in step 168,
An airbag activation permission signal is transmitted to the airbag controller 12.

[0072] At step 170 subsequent to step 168, sensed weight value W is whether or not the threshold value C ₂ or less is determined. As a result, if W ≦ C ₂ holds, it is determined that the occupant has got off the vehicle, and the current routine ends.
On the other hand, if W ≦ C ₂ is not satisfied in step 170, the process of step 168 is executed again, and the transmission of the airbag operation permission signal is continued.

[0073] As described above, according to the routine shown in FIG. 6 and FIG. 7, when the detected weight value W when the mounting operation of the seat belt has been performed is the threshold value C ₁ or less, thereafter, Until the occupant gets off, the determination that the seated occupant is in the lightweight class (child) is continued, and the operation prohibition state of the airbag module 14 is maintained. For this reason, it is possible to maintain the appropriate classification determination of the occupant and prevent the classification from frequently changing.

Further, by combining the determination of the ALR state of the seat belt and the determination of the magnitude relationship between the detected weight value W and the threshold value C3, it is determined whether or not the CRS is worn, and the CRS is worn. In this case, the operation of the airbag module 14 can be prohibited. By the way, in the routine shown in FIGS. 6 and 7, when it is determined that the CRS is mounted by making an affirmative determination in step 162, an airbag operation prohibition signal is transmitted in step 164, and then in step 154.
168 as in the detection weight value W is the threshold C ₂ between greater than it is conceivable to perform processing for repeatedly executing step 164. However, when performing such processing, when CRS as continues to be a long period of time mounted on the vehicle, even while the ignition off in order to perform a comparison between the detected weight value W and a threshold C _2, at all times, the strain sensor 42 , 4
4 needs to be enabled (that is, current supply to the strain sensors 42 and 44 is maintained), and the power consumption of the system is increased.

On the other hand, in the present embodiment, step 1
After 64 exit, since not performed to compare the detected weight value W and a threshold C _2, an ignition-off in the strain sensor 4
There is no need to validate the outputs of 2,44. Therefore, after the end of step 164, in step 102, it is possible to stop energizing the strain sensors 42 and 44,
It is possible to reduce the system power consumption while the ignition is off.

In the third and fourth embodiments, when it is determined that the seated occupant is of the lightweight class, the operation of the airbag module 14 is prohibited. However, in the first and second embodiments, As described with respect to the example, the airbag module 14 may be configured to be deployable with two levels of high and low outputs, and may be deployed with low output when it is determined to be a lightweight class.

In the third and fourth embodiments, the routines shown in FIGS. 5, 6, and 7 are executed regardless of the on / off state of the ignition switch. Each routine may be started when the ignition switch is turned on. In this case, the processing of step 102 is omitted in each routine.

In the third and fourth embodiments, the sheet sensor controller 26 has the strain sensors 42, 4
The sheet sensor controller 26 detects the load detection value W based on the output signal of step 4 in the load detection means and load detection step described in claim 1.
04 and 150 are executed by the seat sensor controller 26 in the occupant classification means and the occupant classification step described in the claims.
Executing the processes of 0 and 162 respectively corresponds to the CRS mounting determination means described in the claims.

In the first to fourth embodiments, the strain caused by the deflection of the beams 38 and 40 is measured by the strain sensors 42 and 44, and the load acting on the seat surface is detected based on the measured values. It was taken. However, the present invention is not limited to this. For example, a pressure measurement film capable of measuring a pressure distribution may be incorporated in a seat cushion of the vehicle seat 10. In this case, the detected weight value W can be obtained by integrating the measured pressure distribution, and by integrating the pressures at the front and rear portions of the seat surface, respectively, the front portion of the detected weight value W can be obtained. And distribution to the rear. Alternatively, the area of the portion where the butt portion of the occupant is seated is obtained from the pressure distribution measured by the pressure measurement film, and based on a comparison between the area and the threshold, the occupant is operated in the same manner as in the first to fourth embodiments. May be divided into classes. In this case, the seating posture of the occupant can be determined based on the position of the seating portion at the buttocks of the occupant.

Further, for example, a load sensor may be provided at a portion where the vehicle seat 10 is mounted on the cabin floor, and a load acting on the seat surface may be detected based on an output signal of the load sensor. Further, in the first to fourth embodiments, the case where the occupants seated in the passenger seat are classified is described, but the same classification may be performed on the driver's seat side. in this case,
In the fourth embodiment, when the ignition switch is turned on while the seat belt is fastened on the driver's seat side, the classification performed at that time may be maintained. That is, when the driver turns on the ignition switch while wearing the seat belt, the driver is considered to be seated deeply in the seat, so the detected weight value W at that time more accurately represents the weight of the occupant. It can be said that. Therefore, by fixing the classification at such a point, appropriate classification can be maintained.

[0081]

According to the first to fifth, eleventh to fourteenth, seventeenth to twentieth, and twenty-second aspects of the present invention, it is possible to prevent frequent changes in the classification of seated occupants. Further, according to the inventions described in claims 6 to 9 and 21, it is possible to appropriately classify according to the change in the sitting posture of the occupant.

Further, according to the tenth aspect, it is possible to prevent classification from being performed based on an incorrect load detection value. Further, according to the inventions described in claims 15 and 16, it is possible to determine whether or not the child restraint device is mounted.

[Brief description of the drawings]

FIG. 1 is a diagram showing a cross section of a system according to an embodiment of the present invention, which is cut at the center of a passenger seat in a vehicle width direction.

FIG. 2 is a perspective view of a vehicle seat in the system according to the embodiment.

FIG. 3 is a diagram illustrating a method for classifying seated occupants in the present embodiment.

FIG. 4 is a diagram for explaining a method of classifying seated occupants in a second embodiment of the present invention.

FIG. 5 is a flowchart of a routine executed by a seat sensor controller in a third embodiment of the present invention.

FIG. 6 is a flowchart (part 1) of a routine executed by a sheet sensor controller in a fourth embodiment of the present invention.

FIG. 7 is a flowchart (part 2) of a routine executed by the sheet sensor controller in a fourth embodiment of the present invention.

[Explanation of symbols]

 Reference Signs List 10 vehicle seat 20 acceleration sensor 26 seat sensor controller 42, 44 strain sensor

 ──────────────────────────────────────────────────続 き Continued on front page F term (reference) 3B087 DE08 DE10 3B088 QA05 3D054 AA02 AA03 BB16 EE09 EE10 EE11 EE13 EE14 EE18 EE19 EE21 EE28 EE29 EE31 FF20

Claims (22)

[Claims] 1. A load detecting means for detecting a load acting on a seat surface of a vehicle seat, and an occupant for classifying a seated occupant into at least two classes based on detection values of the load detecting means at at least two times. And a classifying means. 2. A load detecting means for detecting a load acting on a seating surface of a vehicle seat; and classifying seated occupants based on a magnitude relationship between a detected value of the load detecting means and one threshold value; Thereafter, occupant classification means for maintaining the classification until the magnitude relationship between the detection value of the load detection means and another threshold value different from the one threshold value changes, Seated occupant detection device. 3. The occupant classification means measures an average value of the detected values of the load detection means during a predetermined period, and classifies the occupants based on a magnitude relation between the average value and a threshold value. And maintaining the classification until the magnitude relationship between the average value of the detection values of the load detection means and another threshold value different from the one threshold value changes in a predetermined period thereafter. The seated occupant detection device according to claim 1, wherein 4. The occupant classifying means classifies the seated occupant based on a ratio of a time when a detected value of the load detecting means is equal to or more than a predetermined threshold value in a predetermined period. 2. The seated occupant detection device according to 1. 5. The occupant classification means performs classification based on the magnitude relationship between the time ratio and a predetermined value, and thereafter, the occupant classification unit determines whether the time ratio and the predetermined value are different from each other. 5. The seated occupant detection device according to claim 4, wherein the classification is maintained until the magnitude relationship with the predetermined value changes. 6. The load detecting means is capable of detecting a load acting on a front portion and a rear portion of a seat surface of the seat, respectively, and is classified by the classifying device based on a front-rear distribution of the load acting on the seat surface. The seated occupant detection device according to any one of claims 1 to 5, further comprising a classifying correction unit configured to correct the following. 7. The occupant classification correcting means, when the load acting on the front portion of the seat surface is greater than the load acting on the rear portion of the seat surface beyond a predetermined degree, the classifying device. 7. The seated occupant detection device according to claim 6, wherein the classification is corrected to a lighter side class. 8. A deceleration detecting means for detecting a vehicle deceleration, wherein the classifying and correcting means is configured to determine that the vehicle deceleration exceeds a predetermined value and that a decreasing gradient of a load acting on a rear portion of the seat surface is predetermined. 7. The seated occupant detection device according to claim 6, wherein when the value exceeds the value, the classification by the occupant classification means is corrected to a lighter class. 9. The load detecting means is capable of detecting a load acting on a front part and a rear part of a seat surface of the seat, and the occupant classifying means is capable of detecting a load acting on a front part and a rear part of the seat surface. The occupant detection device according to any one of claims 1 to 5, wherein when the ratio changes at a gradient equal to or greater than a predetermined value, the previous classification is invalidated and a new classification is performed. . 10. An acceleration detecting means for detecting acceleration in at least one of a vehicle longitudinal direction and a vertical direction, wherein the occupant classifying means has an acceleration in at least one of a vehicle longitudinal direction and a vertical direction exceeding a predetermined value. The seated occupant detection device according to any one of claims 1 to 9, wherein a detection value of the load detection means is ignored in such a case. 11. Load detecting means for detecting a load acting on a seat surface of a vehicle seat, and occupant classifying means for classifying a seated occupant into at least two classes based on a detection value of the load detecting means. The occupant classification device, wherein when the occupant classification is performed under predetermined conditions, the classification is fixed thereafter. 12. The seated occupant detection according to claim 11, wherein the occupant classification means fixes the classification at the time when the detected value of the load detection means becomes a predetermined threshold value or more. apparatus. 13. The seated occupant detection device according to claim 11, wherein the occupant classification means fixes the classification at the time when the seat belt is fastened. 14. The occupant classification means is fixed to a classification at the time when an ignition switch is turned on in a state where a seat belt is fastened in a seat on a driver's seat side. Occupant detection device. 15. A CRS wearing determining means for determining that the child restraint device is worn when the seat belt is in the ALR state and the detected value of the load detecting means is equal to or less than a predetermined value. 15. The method according to claim 1, wherein:
The seated occupant detection device according to any one of claims 1 to 4. 16. A sensor suspending means for suspending the operation of the load detecting means when the child restraint device is judged to be worn by the CRS wearing judging means and the ignition switch is turned off. The seated occupant detection device according to claim 15, wherein: 17. A load detecting step for detecting a load acting on a seat surface of a vehicle seat, and a seated occupant is classified into at least two classes based on detection values at least at two time points detected in the load detecting step. And an occupant classification step. 18. A load detecting step of detecting a load acting on a seat surface of a vehicle seat; and classifying seated occupants based on a magnitude relationship between a detected value in the load detecting step and a threshold value; Thereafter, an occupant classification step of maintaining the classification until the magnitude relationship between the detection value of the load detection means and another threshold value different from the one threshold value changes,
A seated occupant detection method comprising: 19. The occupant classifying step includes measuring an average value of the detected values in the load detecting step during a predetermined period, and classifying the seated occupant based on a magnitude relationship between the average value and a threshold value. And maintaining the classification until the magnitude relationship between the average value of the detection values of the load detection means and another threshold value different from the one threshold value changes in a predetermined period thereafter. The method for detecting a seated occupant according to claim 17, wherein 20. The occupant classifying step, wherein the seated occupants are classified based on a ratio of a time during which a value detected by the load detecting step is equal to or greater than a predetermined threshold during a predetermined period. 17. The method for detecting a seated occupant according to claim 17. 21. In the load detecting step, a load acting on a front part and a rear part of a load acting on a seat surface of a seat is detected, and the classifying step is performed based on a front-rear distribution of the load acting on the seat surface. 21. The method for detecting a seated occupant according to any one of claims 17 to 20, further comprising a classifying correction step of correcting the classifying based on the occupant. 22. A load detecting step for detecting a load acting on a seat surface of a vehicle seat, and an occupant classifying step for classifying a seated occupant into at least two classes based on a detected value in the load detecting step. In the occupant classification step, when the classification of the seated occupant is performed under a predetermined condition, the classification is fixed thereafter.