Patent Application
20050173904
This application is based on Japanese Patent Application No. 2004-31660 filed on Feb. 9, 2004, the disclosure of which is incorporated herein by reference.
The present invention relates to a control system for a vehicle occupant protection apparatus, which controls the vehicle occupant protection apparatus in accordance with a condition of an occupant sitting on a vehicle seat.
It has been recently required, according to the US law FMVSS article 208 and the like in relation to an air-bag system installed in a vehicle as an occupant protection apparatus, that two contrary characteristics must be realized in a high level. Namely, one of them is a high occupant protection performance in case of a vehicle crash, and the other one is a decrease of offending possibility to a vehicle occupant, in particular to babies or little children.
It is disclosed in Japanese Paten Publication No. 2001-310668 that a body type of an occupant is judged in accordance with his weight which is measured by a weight sensor provided in a vehicle seat, or in another Japanese Patent Publication No. 2003-127824 that an occupant position is detected by a photographic image around the vehicle seat.
It is, however, according to the above Japanese Patent Publication No. 2001-310668, necessary to provide multiple weight sensors in the vehicle seat, namely at least at four different positions of the seat (a forward right and left, and a backward right and left positions of one seat). Furthermore, it may be necessary to provide a certain means, such as a weight stopper or a link mechanism, for preventing the seat and the weight sensors from being broken down at the vehicle crash, And thereby, the weight sensors may become inevitably large in size and high in cost.
On the other hand, according to the above other Japanese Patent Publication No. 2003-127824, it is necessary to provide an image sensor and a highly advanced calculating devices for the image data processing for judging whether any occupant is seated on the seat, whether the occupant is a baby or little child, and so on. As a result, such system is also high in cost.
In the case that the expansions of the air bags are controlled, bottoming of the air bags must be prevented. For example, the air bag must be expanded at a higher expansion pressure for such an occupant having a heavier weight. However, if the air bag was expanded at such a high expansion pressure for an occupant having a light weight, such as a little child, or for the occupant having the heavier weight but sitting at a forward position of a seat, or for the occupant sitting at a normal position of the seat but an upper body being forwardly inclined, an offending characteristic to the occupant by the expansion of the air bag would be reversely increased.
It is, therefore, required to control the expansion of the air bag in accordance with the weight of the occupant as well as the position of the occupant sitting on the seat (a distance of the occupant from the air bag), to realize the contrary characteristics in the higher level, namely, the improvement of the occupant protection performance and the reduction of the offending characteristic.
The present invention is made in view of the above problems, and it is an object of the present invention to provide a vehicle occupant protection apparatus, which is capable of properly performing a control operation of the occupant protection apparatus in accordance with occupant sitting conditions containing a physique and a seat sitting position of the occupant, while a simple control system can be made in low cost.
According to a feature of the present invention, a vehicle occupant protection apparatus comprises; an occupant protecting device such as an air bag device; a vehicle seat for an occupant, which is mounted on a floor of the vehicle at a front connecting portion and a rear connecting portion; a weight detecting unit provided at the rear connecting portion between a rear portion of the seat and the floor of the vehicle and for outputting a weight signal corresponding to a product of a weight of the occupant sitting on the seat and a distance of a gravity of the occupant from the front connecting portion; a crash sensor provided in the vehicle for outputting a vehicle crash signal; and an electronic control unit for operating the occupant protecting device in accordance with the weight signal and the crash signal.
As a result, the occupant protection apparatus according to the present invention can be made in a simple structure and at low cost. At the same time, the compatibility between the occupant protecting performance and lowering of the off ending characteristic can be improved.
According to another feature of the present invention, a front portion of the seat is fixed to the vehicle floor via a mechanical hinge or an elastic hinge at the front connecting portion, so that a substantial amount of the weight at the rear portion of the seat is applied to the weight detecting unit. As a result, the weight detecting unit can output a detection signal corresponding to a product calculated between the occupant weight and the distance of the occupant gravity from the front portion of the seat in high precision.
According to a further feature of the present invention, the vehicle seat is mounted on a seat sliding device, which comprises a pair of lower seat rails, a pair of upper seat rails connected to the lower seat rails in a slidable manner, and a seat frame of the seat is fixed to the upper seat rails at the front and rear connecting portions via the mechanical or the elastic hinge and the weight detecting unit.
With such an arrangement, the weight detecting unit can likewise output a detection signal corresponding to a product calculated between the occupant weight and the distance of the occupant gravity from the front portion of the seat in high precision.
According to a still further feature of the present invention, a mechanical rigidity of the front connecting portion is lower than that of the weight detecting unit, so that a substantial amount of the weight at the rear portion of the seat is applied to the weight detecting unit.
According to a still further feature of the present invention, the seat is mounted on a seat sliding device, which comprises a pair of lower seat rails, a pair of upper seat rails connected to the lower seat rails in a slidable manner, and a seat frame of the seat is fixed to the upper seat rails, and the lower seat rails are connected to the vehicle floor at the front and rear connecting portions. And a pair of weight detecting unit is provided at the left and right rear connecting portions.
The above and other objects, features and advantages of the present invention will become more apparent from the following detailed description made with reference to the accompanying drawings. In the drawings:
An embodiment of the present invention for a control system for an occupant protection apparatus is explained with reference to the drawings.
As shown in
As shown in
As shown in
The seat frame 11 corresponds to a frame member for supporting the seat cushion 5. The seat frame 11 is equipped with a right and a left frame members 12, and three coupling members 13, 14 and 15. The right and left frame members 12 are extended in a longitudinal direction. The coupling members 13, 14 and 15 are respectively connected to the right and left frame members 12 at front ends, middle portions and rear ends thereof.
The frame members 12 are connected to the upper seat rails 21 at a front and a rear portion of the frame members 12. The upper seat rails 21 are connected to the lower seat rails 22, so that the frame members 12 as well as the upper seat rails 21 are slidable on the lower seat rails in a forward and backward direction.
A front portion of the seat frame 11 is fixed to the upper seat rails 21 by multiple rivets 100a, as shown in
At a rear portion of the seat frame 11, as shown in
As more apparent from
As shown in
A structure of the weight detecting unit 30 will be explained with reference to
As shown in
The ceramic resistance element 32 is arranged between a lower plane of the upper housing member 31b and an upper plane of the lower housing member 31c at a center portion of the inner space 31a within the diagram 31. The ceramic resistance element 32 is contacted with the upper and the lower housing members 31b and 31c, so that a predetermined pressure is applied to the ceramic resistance element 32.
Since the diaphragm 31 is fixed to the coupling member 15 and the rail coupling bar 23 by means of screw-nut coupling, the weight detecting unit 31 can detect the stress in both directions, namely the compression and tension. Furthermore, the predetermined pressure is in advance applied to the ceramic resistance element 32, so that the diaphragm 31 can stably detect the stress applied to the ceramic resistance element 32 in the both directions. And also, the tension strength at the fastening portion of the rear portion 11b of the seat frame 11 is secured.
In this embodiment, the ceramic resistance element 32 constitutes a detecting unit of the present invention, and the diaphragm 31 constitutes a pre-weight applying means.
The ceramic resistance element 32 is made of ceramic material, for instance, zirconia as a major material, which changes its electrical resistance when an external force is applied. Accordingly, the stress (weight) can be detected by detecting the variation of the electrical resistance of the ceramic resistance element 32. The ceramic resistance element 32 is characterized in that the ceramic resistance element 32 owns extremely high rigidity, as compared with that of a strain-gage type weight sensor which is widely used.
Any other types of the sensors can be used as the weight detecting unit 31, in stead of the ceramic resistance element 32, for instance, the well known mechanical amount sensors may be employed which are disclosed in, for instance, Japanese Patent Publications No. 2001-242019 or No. 2002-202209.
The IC circuit 33 is electrically connected to the ceramic resistance element 32, and comprises a circuit portion for outputting a detected weight signal by detecting a change in electric resistances of the ceramic resistance element 32 and a circuit portion for outputting a deployment control signal for the air bag device based upon the detected weight signal. The ceramic resistance element 32 and the IC circuit 33 constitute weight detecting means of the present invention.
The IC circuit 33 is mounted on the lower housing member 31c within the space 31a of the diaphragm 31. The bus bar 34 is a terminal member from which a lead wire 35 is derived, and the lead wire 35 transfers an electric signal outputted from the IC circuit 33. The bus bar 34 is fixed to the diaphragm 31 in such a manner that the bus bar 34 is inserted into a hole 31f formed in the side portion of the diaphragm 31 and is resin-molded. As a result, the inner space 31a is air-tightly sealed. A waterproof connector 36 is provided at the other end of the lead wire 35.
The weight detecting unit 30 is electrically connected via the waterproof connector 36 to the electronic control unit 50, which controls an operation of the air bag device 40 based on the deployment control signal from the weight detecting unit 30 and a signal indicative of a strength of a vehicle crash sensed by a G sensor, etc.
An operation of the respective units of the above embodiment will be explained. At first, a basic principle for detecting weight of a sitting occupant on the seat 2 will be explained with reference to
As described before, the seat frame 11 (the left and right frame members 12) is connected to the upper seat rails 21 at the front connecting portion 11a and the rear connecting portion 11b, at which the weight detecting unit 30 is provided. And a mechanical rigidity of the front connecting portion 11a is formed to be much lower than that of rear connecting portion 11b (the weight detecting unit 30), so that a substantial amount of the weight at the rear portion of the seat 2 is applied to the weight detecting unit 30.
For example, in a model shown in
In the structure, in which the weight detecting unit 30 is arranged at the rear portion of the seat frame 11, a weight loading ratio of the frame member 12 to the ceramic resistance element 32 is determined based upon a ratio of flexure amounts of both the frame member 12 and the ceramic resistance element 32 (in other words, ratio of rigidity of both members), when weight is applied to the rear portion of the seat frame 11.
As a consequence, a weight load “Fs” of the ceramic resistance element 32 is given as follows:
FS=100 Kg×δ seat/(δ seat+δ sensor)≧99.9 Kg.
In other words, a detected weight value in the weight detecting unit 30 becomes larger than, or equal to 99.9 Kg with respect to the applied weight of 100 Kg. As a result, the weight applied to the seat 2 can be detected in high precision by the single ceramic resistance element 32 arranged at the rear connecting portion 11b of the seat frame 11.
A relationship, between the detected weight values by the weight detecting unit 30 and distances from the front connecting portion 11a of the seat frame 11 to gravity positions of occupant, will be explained with reference to
A line “AM50” is measurement results for a 50th percentile adult male having weight of 80 Kg, a line “AF05”, for a 5th percentile adult female having weight of 48 Kg, a line “6yo+booster” for a 6-years-old child using a booster seat, a line “3yo+CRS” for a 3-years-old child using a child restraint, and a line “1yo+CRS” for a 12-month-old child using a child restraint.
As apparent from
As above, a value corresponding to a product between a mass M and a distance L is detected by the ceramic resistance element 32, wherein the mass M is a mass of an upper body of an occupant, and the distance L is a distance of the gravity of the occupant from the front connecting portion 11a, as indicated in
It has been known that the smaller a physique (namely, mass M) of an occupant becomes, the larger an offending characteristic becomes, whereas the larger the physique (mass M) of the occupant becomes, the smaller the offending characteristic becomes.
According to the US laws and regulations, obstacle values when a vehicle crashes under the conditions of AM50, AF05, and CRS (child restraint is mounted) at the proposed range of seating position have been defined. And the obstacle values can be satisfied by detecting AM50, AF05 and CRS at the respective proposed range of seating positions (Refer to
It has been also known that the closer a seat sitting position of an occupant is located to an air bag, the larger an offending characteristic becomes, whereas the further separated the seat sitting position of the occupant is from the air bag, the smaller the offending characteristic becomes.
In the case that a distance from the air bag 40 to the front connecting portion 11a is fixed, a distance from the air bag 40 to the seat sitting position of the occupant is determined based upon a distance “L” defined from the above-described front connecting portion 11a to the gravity position of the occupant. As a consequence, the shorter the distance “L” becomes the larger the offending characteristic caused by the deployment of the air bag 40 becomes, whereas the longer the distance “L” becomes, the smaller the offending characteristic becomes.
According to the embodiment of the present invention, the IC circuit 33 is arranged in such a manner that the IC circuit 33 outputs a deployment control signal of the air bag 40 based upon a detected weight value (namely, value corresponding to product by mass “M” and distance “L”) obtained from a change of electric resistances in the ceramic resistance element 32.
The deployment control signals are outputted in response to deployment modes of the air bag 40, wherein the deployment modes have three different stages, namely, a high deployment mode; a low risk deployment mode; and a suppression mode.
The “high deployment” mode is a mode in which a deployment amount of the air bag 40 is maximum. For example, in the case that an adult male sits at the proposed range of seating position, a deployment control signal (will be referred to as “high deployment signal” hereinafter) corresponding to the high deployment mode is outputted from the IC circuit 33.
The “low risk deployment” mode is a mode in which a deployment amount of the air bag 40 is suppressed to a predetermined deployment amount (for instance, 60% of maximum deployment amount). In the case that an adult female sits at the proposed range of seating position; in the case that a child of 6 years old sits on the booster seat; in the case that an adult male sits at a slightly forward position from the proposed range of seating position; and the like, a deployment control signal (will be referred to as “low risk deployment signal” hereinafter) corresponding to the low risk deployment mode is outputted.
The “suppression” mode is a mode that the air bag 40 is not deployed. For instance, in the case that a child of 12-month-old sits on a child restrained; in the case that occupants of all types of physiques including an adult male sit at extremely forward positions from the proposed range of seating position; and the like, a deployment control signal (will be referred to “suppression signal” hereinafter) corresponding to the suppression mode is outputted.
As to the detected weight value (namely, value corresponding to mass “M”×distance “L”) based on the output of the ceramic resistance element 32, as shown in
A process for the deployment control signals will be explained with reference to a flow chart shown in
At a step S1, the CPU determines whether a detected weight value from the ceramic resistance element 32 is larger than, or equal to the first threshold value. And in the case that the detected weight value is larger than, or equal to the first threshold value (S1: Yes), the process goes to a step S2 at which the IC circuit 33 outputs the “high deployment” signal. On the other hand, in the case that the detected weight value is smaller than the first threshold value (S1: No), the process goes to a step S3, at which the CPU determines whether or not the detected weight value is larger than, or equal to, the second threshold value.
In the case that the detected weight value is larger than, or equal to the second threshold value (S3: Yes), the process goes to a step S4, at which the IC circuit 33 outputs the “low risk deployment” signal. On the other hand, in the case that the detected weight value is smaller than the second threshold value (S3: No), the process goes to a step S5, at which the IC circuit 33 outputs the “suppression” signal.
As above, according to the occupant protection system 1, when the occupant sits on the seat 2, the ceramic resistance element 32 of the weight detecting unit 30, which is provided between the seat rear portion and the vehicle body, outputs such a value corresponding to the product calculated by multiplying the weight of the occupant and the distance of the occupant gravity from the seat front portion. And the IC circuit 33 outputs the deployment control signal of the air bag 40 based upon the output value of the ceramic resistance element 32.
Then, the electronic control unit 50 deploys the air bag 40 in accordance with the deployment mode (namely, high deployment mode, low risk deployment mode, or suppression mode) designated by the deployment control signal outputted from the weight detecting unit 30, when the crash of the vehicle is sensed by the crash sensor.
According to the occupant protection system 1, the deployment control operation of the air bag 40 is carried out in a proper manner in response to the occupant conditions which contain the physiques and the seat sitting positions of the occupants, at the same time the simple and low cost arrangement of the occupant protection system 1 is realized. Furthermore, the compatibility between the occupant protection performance of the air bag 40 and lowering of the offending characteristic thereof with respect to the occupant can be improved.
Furthermore, since the weight detecting unit 30 is provided between the coupling member 15 and the rail coupling bar 23, the weight detecting operation can be carried out in high precision by merely providing the weight detecting means at one place. Also, since both the ceramic resistance element 32 and the IC circuit 33 are built in the diaphragm 31, both the weight detecting operation and the air bag deployment control operation executed in response to the occupant condition can be realized by the single unit. In particular, since the compact ceramic resistance element 32 having the high rigidity is employed as the weight detecting unit, the weight detecting unit 30 can be made in a very small size.
A first modification of the present invention is explained with reference to
A second modification of the present invention is explained with reference to
A third modification of the present invention is explained with reference to
The rear portion of the seat frame 11 is fastened to the upper seat rail 21 by rivets 100b in the same manner to the front portion of the seat frame 11. On the other hand, the lower seat rail 22 is fixed via the weight detecting unit 30 to the vehicle body. The lower portion of the lower seat rail 22 is fixed to the upper portion of the weight detecting unit 30 by rivets, and the lower portion of the weight detecting unit 30 is fixed to a bracket 22c by rivets. The bracket 22c has been fixed to the vehicle body 200 by a bolt 22d. In this third modification, since the weight detecting units 30 are provided at two (right and left) places, the seat sitting position of the occupant can be detected not only along the front-rear direction, but also along the right-left direction.
Furthermore, since the weight is detected by the weight detecting unit 30 in response to the slide position of the seat frame 11 along the front-rear direction, the deployment control operation of the air bag 40 can be carried out by also considering the slide position of the seat 2.
Furthermore, since the weight detecting operations are separately carried out on the right and left sides of the seat 2, a deployment control operation for a side air bag may be carried out based upon a gravity position of the occupant along the right-left direction of the seat 2.
The present invention is not limited to the above-explained embodiment or modifications, but may be modified and changed without departing from the technical scope and spirit of the present invention.
For example, multiple switching means can be used to detect a slide position of the seat frame in the front-rear direction, wherein those switches will be turned on or off depending on the slide position. And the deployment control signals are generated with a combination of the weight detection signals from the weight detecting unit 30 and the signals from the above switches, so that a more precise operation can be realized. For example, a position switch is provided on the lower seat rail 22, so that the switch is turned ON when the upper seat rail 21 is located at a forward position from the intermediate position, whereas the switch is turned OFF when the upper seat rail 21 is located at a backward position from the intermediate position. As a result, the slide positions of the seat 2 can be detected in two stages.
Further, an image sensing apparatus can be additionally provided for sensing a seat sitting condition of an occupant by an image, so that the information of the occupant detected by the image sensing apparatus and the information detected by the weight detecting unit 30 can be combined. As a result, an occupant condition can be detected in much higher precision.
The fastening structure in the front connecting portion of the seat 2 is not limited to the fastening structures disclosed in the above embodiment or modifications. Any other modified fastening structure can be possible, in which rigidity of a fastening portion to the side of the vehicle body in the front portion of the seat 2 is set to be relatively lower than the rigidity of the weight detecting means which is provided between the vehicle body and the rear portion of the seat 2.
A strain-gage type detecting element, a static capacitance type detecting element or the like can be used, instead of the ceramic resistance element 32, as the weight detecting element, which have been widely and generally utilized.
Furthermore, instead of the deployment control signals of the three stages (the high deployment mode, the low risk deployment mode, and the suppression mode), two stages of the high deployment mode and the suppression mode can be employed.
The expansion control signal can be generated in a linear manner, if the air bag is of a type in which the air bag is controlled in the linear manner.
The present invention can be used to other types of the occupant protecting devices, such as a seat belt device having a pre-tensioning function, a seat belt device in which a seat belt is wound back by an electric motor at a vehicle crash, and so on.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2004-31660 | Feb 2004 | JP | national |
