JP4542828B2 - Load fluctuation detection device and seat - Google Patents

Description

  The present invention relates to a load fluctuation detection device using a torsion bar whose torsion angle changes due to load fluctuation and a seat provided with the load fluctuation detection device.

For example, in order to automatically switch the operation control of an air bag, as a technique for automatically distinguishing whether an occupant seated on a seat is an adult or a child and feeding it back to the operation control unit of the air bag, A sheet having a mechanism for automatically detecting the above is known. Normally, urethane foam is used as a cushioning material, so it is possible to detect the weight by measuring the amount of displacement of a coil spring that supports the urethane foam and is arranged vertically on the vehicle body floor, and the magnitude of the amount of displacement. Has been done.
On the other hand, in recent years, as disclosed in Patent Document 1, a cushion material provided in a seat cushion portion is elastically supported by a torsion bar disposed at a rear portion of the seat cushion portion, and is seated on a cushion frame. Is disclosed.
JP 2003-182427 A

  Since the sheet | seat disclosed by patent document 1 is not the structure which mounts a thick urethane foam on a flame | frame, a lighter sheet | seat can be provided. However, since such a seat is not displaced in the vertical direction like the above-described coil spring, conventional weight detecting means cannot be used. By attaching a strain sensor to the torsion bar, it is conceivable to measure distortion due to torsion of the torsion bar, but not only when a person is seated, but also due to vibrations during body movement and running. Since torsional torque is repeatedly applied due to load fluctuations, there is a problem in terms of durability when a strain sensor is attached. In this respect, there is a similar problem not only in the seat but also in the case of detecting a load fluctuation of a load support that elastically supports a load using a torsion bar.

  The present invention has been made in view of the above points, and can detect a load variation applied to a load support that elastically supports a load using a torsion bar with a simple structure and is excellent in durability. It is an object of the present invention to provide a load variation detection device and a seat including the load variation detection device.

In order to solve the above-described problem, in the invention according to claim 1, a torsion bar that is connected to a load support and changes a torsion angle due to a load variation;
A magnetic bar member that is not distorted by the load variation;
An exciting coil in which the torsion bar and the magnetic bar member are collectively wound around them;
A first pickup coil wound around the torsion bar;
A second pickup coil wound around the magnetic bar member;
There is provided a load fluctuation detecting device comprising difference output means for outputting a difference between output values of the first pickup coil and the second pickup coil.
According to a second aspect of the present invention, the load support body is a seat, and the torsion bar elastically supports a cushion member for the seat cushion disposed in the seat cushion portion. The load variation detecting device according to claim 1, wherein the load variation detecting device is provided along the line.
According to a third aspect of the present invention, the load support is a seat, and the torsion bar elastically supports a cushion member for the seat back disposed in the seat back portion. The load variation detecting device according to claim 1, wherein the load variation detecting device is provided along the line.
According to a fourth aspect of the present invention, there is provided a seat comprising the load fluctuation detecting device according to the second or third aspect.

  The present invention includes a torsion bar whose torsion angle changes due to load fluctuations and a magnetic bar member that does not distort due to load fluctuations, and is excited by an excitation coil that is wound around the torsion bar and the magnetic bar members together. The difference between the voltage value output from the first pickup coil wound around the torsion bar and the voltage value output from the second pickup coil wound around the magnetic bar member is output. It is a structure. Therefore, it is possible to detect a slight fluctuation of the torsion angle of the torsion bar with high sensitivity. In addition, the torsion bar and the magnetic bar member are disposed so as to be surrounded by the excitation coil and each pickup coil and loosely inserted, and are not directly fixed to the torsion bar. Compared with durability.

  In addition, since the difference between each pickup coil is output as described above, it is possible to detect slight fluctuations in the torsion angle of the torsion bar. For example, when applied to a seat, the weight of the occupant can be detected. In addition to this, it is possible to detect a slight body movement transmitted to the cushion material through the muscles due to breathing or pulse waves, or a load variation applied to the load support (seat) due to vibration transmitted during riding. Therefore, by detecting load fluctuations due to such body movements in time series, the obtained data is processed, and the respiratory rate and respiratory frequency are calculated to obtain respiratory fluctuations and the magnitude of body movements associated with breathing. It is suitable for use as a sensor that captures changes in the state of mind and body of the occupant (whether they are awake or sleep, etc.).

  Hereinafter, the present invention will be described in more detail based on embodiments shown in the drawings. 1-3 is a figure for demonstrating the load fluctuation detection apparatus 1 which concerns on one Embodiment of this invention. In the present embodiment, the load fluctuation detection device 1 is mounted on a vehicle seat 100.

  The seat 100 includes a base cushion material 120 that is stretched around the cushion frame 110. A rear portion of the cushion frame 110 is provided along the width direction, and a torsion bar 2 constituting the load fluctuation detection device 1 of the present embodiment is provided. The base cushion material 120 is elastic to the torsion bar 2. Supported. Specifically, the rear portion 121 of the base cushion material 120 is connected to the support frame 112 that is supported by the arm member 111 provided on one end side and the other end side of the torsion bar 2 and is disposed along the width direction. The front portion 122 is disposed to be engaged with the front frame 113 of the cushion frame 110.

  A surface cushion material 130 is disposed on the base cushion material 120. The surface cushion material 130 is connected to the base cushion material 120 at the rear portion and to the lower portion of the back cushion material 150 that is stretched on the back frame 140. In the present embodiment, the surface cushion material 130 made of another member is provided on the upper portion of the base cushion material 120, and these are combined to constitute the cushion material for the seat portion. Instead of such a laminated structure, only one sheet may be used, or a laminated structure of three or more layers may be used.

  As in the present embodiment, the base cushion material 120 is configured by the base cushion material 120 and the surface cushion material 130 as the seat cushion material, so that the base cushion material 120 is given tension by the elastic force of the torsion bar 2. Therefore, the floor vibration can be effectively damped and the vibration transmission to the surface cushion material 130 can be reduced. On the other hand, the surface cushion material 130 is stretched to the cushion frame 110 with low tension. Thereby, the human muscles (especially the buttocks muscles) are less compressed when seated and do not hinder muscular movements due to blood vessel expansion / contraction movements, breathing or body movements. As a result, mixing of external vibration noise into the load fluctuation signal data collected by the load fluctuation detection device 1 is reduced, and a pressure fluctuation (load fluctuation) signal resulting from respiration that appears as a slight torsion fluctuation of the torsion bar 2. Can be detected more accurately.

  The surface cushion material 130 and the back cushion material 150 constituting the seat cushion material can be formed of a two-dimensional net material, a thin urethane material, or the like, but in order to reduce pressure on the buttocks muscles and the like. It is preferable that the spring characteristics when these are stretched on the cushion frame 110 be as close as possible to the spring characteristics of the buttocks muscles and the like. As the cushion material having such characteristics, the applicant preferably uses, for example, a three-dimensional knitted fabric with a small reaction force disclosed in JP-A-2002-336076. The three-dimensional knitted fabric is formed using, for example, a double raschel knitting machine or the like, and is knitted by reciprocating a connecting yarn between a pair of ground knitted fabrics positioned at a predetermined interval. The base cushion material 120 can also be a two-dimensional net material, a three-dimensional knitted fabric, or the like, similarly to the surface cushion material 130.

  The load fluctuation detection device 1 according to the present embodiment includes the above-described torsion bar 2 and a magnetic bar member 3 provided in parallel with the torsion bar 2. As described above, the torsion bar 2 supports the base cushion material 120 that constitutes the cushioning material for the seat portion. Therefore, when a person is seated, when body movement occurs due to breathing or the like, a load fluctuation occurs. The twist angle changes. On the other hand, the magnetic bar member 3 is arranged so as not to be twisted, that is, not distorted even if such load fluctuation occurs. The magnetic bar member 3 may not be arranged in parallel with the torsion bar 2 as long as the magnetic bar member 3 is not distorted due to load fluctuations. By arranging in parallel as shown in FIG. 3, it contributes to space saving.

  As shown in FIGS. 2 and 3, the first pickup coil 4 is wound around the torsion bar 2 in one direction, and the first pickup coil is provided around the magnetic bar member 3. A second pickup coil 5 is provided which is wound so as to be in a direction opposite to that of 4. And these are accommodated in the coil case 7, and the exciting coil 6 is wound around it. With this configuration, the magnetic bar member 3 is supported by the torsion bar 2 via the coil case 7 and can be arranged so as not to be affected by load fluctuations. However, in order to prevent abnormal noise from being generated due to vibration or the like, it may be configured to be locked to an arbitrary part or the like of the cushion frame 110 in order to prevent the vibration. The magnetic bar member 3 may be made of a magnetic material, but the same material as that of the torsion bar 2 can be used. The magnetic bar member 3 has an output value from the first pickup coil 4 wound around the torsion bar 2 and an output value from the second pickup coil 5 wound around the magnetic bar member 3. It is provided for obtaining the difference, and it is only necessary to be able to perform such a function. The length thereof is not limited, and the second pickup coil 5 is wound as shown in FIGS. 1 and 2. It suffices to have the length necessary to make it. Further, the output values from the first pickup coil 4 and the second pickup coil 5 are outputted after the difference between the output values is obtained by a difference output means comprising a control circuit.

  According to the present embodiment, an induced current is passed through the exciting coil 6 from an AC power source (not shown). When a person is seated, a load is applied to the surface cushion member 130 and the planar support member 120 constituting the cushion material for the seat portion, so that the support frame 112 and the arm member 111 tilt forward, and the torsion bar 2 is twisted. The angle changes. As a result, a predetermined induced voltage is output from the first pickup coil 4. The difference between the output value and the output value from the second pickup coil 5 is calculated by the difference output means. Then, for example, the load is measured by comparing the difference between the output voltage values with a table or graph in which the correlation between the voltage value and the load is taken.

  Also, when the torsion angle of the torsion bar 2 changes due to body movement accompanying breathing or the like, the induced voltage from the first pickup coil 4 is compared with the output value from the second pickup coil 5 in the same manner as described above. By obtaining the difference between the two, the magnitude of the load fluctuation can be detected. Then, if this is taken in time series, it can be used for the analysis of the mind and body condition as described above.

  In the above-described embodiment, the load variation detection device 1 (saddle part sensor) is provided in the seat cushion part. However, as illustrated in FIG. 4, the seat back part can be provided as a back part sensor. When detecting the weight of a person, it is only necessary to provide a load fluctuation detection device 1 (a hip sensor) in the seat cushion part. A device 1 (back sensor) is preferably provided. As a result, when detecting body movement or the like due to breathing, instead of detecting only from one of the seat cushion part and the seat back part, it is possible to use, for example, a person that can acquire more prominent data. it can. Of course, if not used for weight detection, the load fluctuation detection device 1 (back sensor) may be provided only in the seat back portion. Note that the configuration of the load fluctuation detection device 1 (back sensor) provided in the seat back portion is exactly the same as that in the above embodiment, and via a torsion bar 2 disposed in the width direction near the lower portion of the seat back portion. A planar support member (not shown) for the back portion is elastically supported, and the difference between the pickup coils 4 and 5 is output.

(Test example)
FIG. 5 is a graph showing the relationship between the magnitude of vibration and the output voltage. As shown in FIG. 7A, when a 40 kg weight 520 is hung on an arm 510 connected to a torsion bar 500, and is pushed down 10 mm downward and released as shown in FIG. 7B. The voltage change of was investigated. Although not shown, the torsion bar 500 has a first pickup coil wound around it and a magnetic rod member around which the second pickup coil is wound. Is wound, and the output value is the difference between the two pickup coils. The excitation frequency was 50 Hz, and the sampling time was 10 μs.

  On the other hand, FIG. 6 shows an output value obtained from the pickup coil using a structure in which an excitation coil and a pickup coil are simply wound around the torsion bar 500 without using a magnetic bar member.

  It can be seen that the output value based on the difference in FIG. 5 is larger than the output value in FIG. Therefore, it can be seen that, as in the present invention, by providing the magnetic bar member 3 in addition to the torsion bar 2 and taking the difference between the output values of the two, a slight fluctuation in the torsion angle of the torsion bar 2 can be detected sensitively.

FIG. 1 is a perspective view showing a schematic configuration of a seat to which a load variation detection device according to one embodiment of the present invention is attached. FIG. 2 is a diagram illustrating a schematic configuration of the load variation detection device according to the embodiment. FIG. 3 is a cross-sectional view taken along the line AA of FIG. FIG. 4 is a perspective view showing a schematic configuration of a seat in which a load variation detecting device is attached to the seat back portion in addition to the seat cushion portion. FIG. 5 is a graph showing the relationship between the magnitude of vibration and the output voltage of the load variation detection device according to the embodiment. FIG. 6 is a graph in which a pickup coil and an excitation coil are wound around a torsion bar without using a magnetic bar member, and the relationship between the magnitude of vibration and the output voltage is measured. FIGS. 7A and 7B are diagrams for explaining the measurement method of the test example.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Load fluctuation detection apparatus 2 Torsion bar 3 Magnetic bar member 4 1st pickup coil 5 2nd pickup coil 6 Excitation coil 100 Seat 110 Cushion frame 120 Planar support member 130 Surface cushion material 140 Back frame 150 Back cushion material

Claims (4)

A torsion bar connected to the load support, the torsion angle changing due to load fluctuations;
A magnetic bar member that is not distorted by the load variation;
An exciting coil in which the torsion bar and the magnetic bar member are collectively wound around them;
A first pickup coil wound around the torsion bar;
A second pickup coil wound around the magnetic bar member;
A load fluctuation detection device comprising: a difference output means for outputting a difference between output values of the first pickup coil and the second pickup coil.   The load support is a seat, and the torsion bar is disposed along the width direction in the seat cushion portion in order to elastically support the cushion member for the seat cushion disposed in the seat cushion portion. The load fluctuation detection device according to claim 1, wherein   The load support is a seat, and the torsion bar is disposed along the width direction in the seat back portion in order to elastically support the cushion member for the seat back disposed in the seat back portion. The load fluctuation detection device according to claim 1, wherein   A sheet comprising the load fluctuation detection device according to claim 2.

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