JP2009053142A - Sensor fixing structure - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a sensor fixing structure which can be fastened without restrictions of a fixing portion and with which bad influence by resonance can be eliminated. <P>SOLUTION: When measuring vibration generated in a measurement object 10, such as a machine and a vehicle by a sensor 20 equipped with a sensor body 22, such as an acceleration sensor and an oscillation sensor, the sensor 20 is adhered to the measurement object 10 through an intervention member 30 made of high polymer materials having absorption property around the resonance frequency of the sensor 20. Thereby, the sensor can be simply fixed to an optional portion of the measurement object 10 and would be free of the restrictions of the fixing portion. Since vibration of the resonance frequency entering the sensor 20 can be effectively blocked by the intervention member 30, bad influence by resonance can be eliminated, and accurate measurement can be achieved. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a structure for attaching a sensor for measuring vibration generated in a measurement object to the measurement object.

  Conventional sensor mounting structures for measuring vibration and acceleration include, for example, an acceleration sensor mounting method disclosed in Japanese Patent Laid-Open No. 11-242047 (Patent Document 1) and Japanese Patent Laid-Open No. 2001-337100 (Patent Document 2). There is known a mounting structure of a sensor disclosed in the above.

  The acceleration sensor mounting method disclosed in Patent Document 1 is based on the premise of mounting an acceleration sensor used in an airbag system. In such an airbag system, a collision is determined based on a signal from an acceleration sensor. Therefore, unnecessary vibration (signal due to resonance or the like) outside the band must be removed because it causes a malfunction. When the resonance frequency is close to the sampling frequency, or when the resonance level is high, a signal due to resonance that is not related to the collision signal appears in the band due to the sampling relationship (aliasing, etc.) during A / D conversion, and the collision occurs. May cause malfunction.

  In order to prevent such a malfunction, the acceleration sensor mounting substrate holding the acceleration sensor is attached to the mating member at one of the front and rear of the acceleration sensor in the direction of acceleration detection and at two places on the left or right. Provide mounting holes for fixing with screws. As a result, the resonance frequency is increased or the resonance level is lowered, and the harmful effects due to resonance are eliminated. Therefore, it is possible to omit the filter added to the inside and outside of the acceleration sensor, which has been necessary conventionally, and a simple and low-cost acceleration sensor mounting structure can be realized.

In the sensor mounting structure disclosed in Patent Document 2, a housing for accommodating the acceleration sensor is provided with a mounting portion for forming one or a plurality of insertion grooves between the housing bottom surface and fixed to the mounted site. One or a plurality of insertion pieces to be inserted into the insertion grooves are provided at important points of the bracket, and caulking pieces that are caulked to the mounting portion side after being inserted into the insertion grooves are provided on the insertion pieces, and the caulking pieces are at least inserted pieces. Can be visually recognized from the outside in a state of being inserted into the insertion groove. As a result, the attachment state can be easily verified, and rattling and loosening are less likely to occur during use.
Japanese Patent Application Laid-Open No. 11-242047 JP 2001-337100 A

  When measuring vibrations of machines, vehicles, etc. using acceleration sensors or vibration sensors, various vibration frequencies are generated from these. If the resonance frequency of the sensor is included in this vibration spectrum, the acceleration sensor or vibration sensor Since the sensor has a resonance frequency due to its structure, there is a problem that when the resonance frequency is input, the sensor output vibrates greatly as the sensor output is saturated, and an accurate value cannot be measured or cannot be measured.

  The acceleration sensor mounting method disclosed in Patent Document 1 can eliminate the harmful effects of resonance, but the increase in the resonance frequency and the decrease in the resonance level are caused by the size and weight of the acceleration sensor used and the size of the acceleration sensor mounting substrate. Since it varies depending on the sheath thickness, the distance of the screw mounting hole from the acceleration sensor, etc., it is troublesome to specify the position of the mounting hole for fixing. Furthermore, since the acceleration sensor mounting substrate is fixed to the mating member using a screw, the mounting to the mating member where the screw cannot be used cannot be performed.

  Further, in the sensor mounting structure disclosed in Patent Document 2, since the housing that houses the acceleration sensor is fixed to the mounting site by caulking pieces, there is a problem caused by resonance as in the method disclosed in Patent Document 1. It cannot be removed.

  The present invention has been made in view of the above-mentioned problems, and an object of the present invention is to provide a sensor mounting structure that can be easily mounted without being restricted by mounting locations and can eliminate the adverse effects caused by resonance. .

  In order to achieve the above object, the present invention provides a sensor mounting structure in which a sensor for measuring vibration generated in a measurement object is attached to the measurement object, and a temperature within a predetermined frequency band including a resonance frequency of the sensor. A member made of a polymer material having a glass transition temperature (Tg) obtained by a frequency conversion law is mounted on the sensor and interposed between the sensor and the measurement object, and the member made of the polymer material A sensor mounting structure bonded to the measurement object is proposed.

  In the sensor mounting structure of the present invention, a member made of a polymer material is interposed between the measurement object and the sensor, the member attached to the sensor is bonded to the measurement object, and the sensor is fixed to the measurement object. The Further, since the polymer material constituting the member has a glass transition temperature (Tg) obtained by a temperature-frequency conversion rule within a predetermined frequency band including the resonance frequency of the sensor, the member has the glass transition temperature. Absorbs vibrations having a frequency corresponding to (Tg).

  According to the sensor mounting structure of the present invention, a member made of a polymer material having an absorption characteristic near the resonance frequency of a sensor when measuring vibration generated in a measurement object such as a machine or a vehicle by an acceleration sensor or a vibration sensor. Since it is attached by adhering the sensor to the object to be measured via the sensor, it can be easily attached to any part of the object to be measured. Since the vibration of the resonance frequency input to the sensor is effectively cut off by the member, the adverse effect due to resonance can be eliminated, and accurate measurement can be performed.

  Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

  FIG. 1 is a diagram showing a sensor mounting structure according to a first embodiment of the present invention. In the figure, reference numeral 10 denotes an object to be measured, which generates vibration like a machine or a vehicle. Reference numeral 20 denotes a sensor device. A sensor substrate 23 having a sensor main body 22 composed of a vibration sensor and an acceleration sensor soldered to the upper surface thereof is provided in a case 21, and a plurality of support members 24 are provided on the lower surface of the sensor substrate 23. The upper surface is bonded, and the lower surface of the support member 24 is bonded to the inner bottom surface of the case 21. Thereby, the sensor main body 22 is fixed inside the case 21.

  An interposition member 30 has a rectangular plate shape with a predetermined thickness D, and its upper surface is bonded to the outer bottom surface of the case 21 of the sensor 20 and its lower surface is bonded to the surface of the measurement object 10. Further, the interposition member 30 is made of a polymer material having absorption characteristics near the resonance frequency of the sensor 20. The JIS / A hardness of the polymer material used in the present embodiment is a value in the range of 30-60. If the JIS / A hardness is less than 30, the material is too soft and the mounting position of the sensor gradually shifts (cold flow), or when the strength is insufficient and a large acceleration is applied, it is greatly deformed or destroyed. It is not preferable because it is lost. On the other hand, when the JIS / A hardness exceeds 60, the vibration absorbing ability is reduced and the effect is reduced, which is not preferable. Further, the thickness D of the interposition member 30 is preferably set to a value within the range of 0.5 mm to 30 mm. That is, if the thickness D is 0.5 mm or less, the volume of the polymer material becomes too small and vibration absorption performance may be insufficient, and if the thickness D is 30 mm or more, vibration is originally measured. The sensor may be too far away from the desired site, making it impossible to achieve the desired purpose, and when a large acceleration is applied, the polymer material itself tends to be deformed, which may affect the measurement. Absent.

  The sensor mounting structure configured as described above absorbs vibration near the resonance frequency of the sensor 20 when measuring the vibration generated in the measurement object 10 such as a machine or vehicle by the sensor 20 having the sensor body 22 such as an acceleration sensor or a vibration sensor. Since the sensor 20 is attached by adhering to the measurement object 10 via the intervening member 30 made of a polymer material having characteristics, it can be easily attached to an arbitrary place of the measurement object 10, so There are no restrictions. Further, since the vibration of the resonance frequency input to the sensor 20 (sensor body 22) is effectively cut off by the interposition member 30, the harmful effect due to the resonance can be eliminated and accurate measurement can be performed.

  Specifically, for example, if the resonance frequency of the sensor 20 is 1 kHz, the sensor 20 is attached via an interposition member 30 made of a polymer material having a glass transition temperature Tg near 0 ° C., for example, synthetic rubber such as SBR. The relationship between the vibration frequency that can be absorbed by the polymer material and the glass transition temperature Tg of the polymer material can be obtained from the temperature-frequency conversion law. The higher the resonance frequency, the lower the glass transition temperature Tg. An intervening member 30 made of a material is used. The temperature-frequency conversion rule is described in “Basics of New Rubber Technology (Edited by Japan Rubber Association) P78-P79” and the like.

  Since the glass transition temperature Tg is almost determined by the type of polymer material, when the bandwidth of the vibration frequency to be absorbed is wide, there are two types having the glass transition temperature Tg at or near the upper limit frequency and lower limit frequency of the frequency band. The desired vibration absorbing performance can be obtained by mixing the mutually incompatible polymer materials in an arbitrary ratio (for example, 50:50). In addition, since the vibration absorption characteristic of the polymer material slightly shifts depending on the use temperature, it is desirable to set the vibration absorption characteristic of the interposition member 30 wider than the resonance frequency bandwidth of the sensor 20.

  Since the low-frequency region corresponds to a physical property near normal temperature in the polymer material, the loss factor tanδ near the normal temperature of the polymer material is lower in order to efficiently transmit the vibration generated by the measurement object 10 to the sensor 20. Is desirable. Specifically, the loss coefficient tanδ at 25 ° C. corresponding to around several Hz is desirably 0.3 or less, and more desirably 0.2 or less.

  Further, as the sensor 20, it is preferable to use a sensor whose resonance frequency is sufficiently high away from the vibration frequency region to be measured. For example, if the vibration frequency measured by the sensor 20 is 1 kHz, the resonance frequency of the sensor 20 is preferably 2 kHz or more.

  Next, examples and comparative examples relating to the polymer material will be described.

  FIG. 2 is a diagram for explaining an example of the polymer material in the first embodiment of the present invention. In the figure, when the interposition member 30 is formed using different polymer materials in Examples 1 to 5 and Comparative Examples 1 and 2, the glass transition temperature Tg, the carbon blending amount, the JIS / A hardness, the member thickness, In addition, experimental results of vibration absorption characteristics are shown.

  The carbon blending amount (parts by weight) is the blending amount of carbon with respect to the polymer 100. JIS / A hardness is measured in accordance with JIS / K6253. In the vibration absorption characteristic experiment, an acceleration sensor is attached to the interposition member 30 made of the material of each example, and the output level when a 1G sine wave is input is classified in the following range. That is, ◎ indicates that the vibration attenuation level is 10 dB or more, ◯ indicates that the vibration attenuation level is 3 to 10 dB, and Δ indicates that the vibration attenuation level is 3 dB or less.

  In Example 1, butadiene rubber (BR) was used as the polymer material, the carbon content was 30 parts, and the member thickness was 10 mm. The glass transition temperature Tg was about −100 ° C., and the JIS / A hardness was 40. It is. As a result of the vibration absorption characteristic experiment of this material, the vibration attenuation level is 3 dB or less at an excitation frequency of 5 Hz, 50 Hz, 500 Hz, and 3000 Hz, the vibration attenuation level is 3 to 10 dB at an excitation frequency of 10 kHz, and the excitation frequency. However, the vibration attenuation level was 10 dB or more at 50 kHz.

  In Example 2, natural rubber (NR) was used as the polymer material, the carbon content was 20 parts, and the member thickness was 10 mm. The glass transition temperature Tg was about −60 ° C., and the JIS / A hardness was 43. It is. As a result of the vibration absorption characteristic experiment of this material, the vibration attenuation level is 3 dB or less at an excitation frequency of 5 Hz, 50 Hz, and 500 Hz, the vibration attenuation level is 3 to 10 dB at an excitation frequency of 3000 Hz, and the excitation frequency is 10 kHz. The vibration attenuation level was 10 dB or more, and the vibration attenuation level was 3 dB or less at an excitation frequency of 50 kHz.

  In Example 3, butyl rubber (IIR) was used as the polymer material, the carbon content was 30 parts, and the member thickness was 10 mm. The glass transition temperature Tg was about −35 ° C., and the JIS / A hardness was 45. is there. As a result of the vibration absorption characteristic experiment of this material, the vibration attenuation level is 3 dB or less at the excitation frequency of 5 Hz and 50 Hz, the vibration attenuation level is 10 dB or more at the excitation frequency of 500 Hz, 3000 Hz, and 10 kHz, and the excitation frequency is The vibration attenuation level was 3 to 10 dB at 50 kHz.

  Example 4 uses norbornene rubber (NOR) as a polymer material, has a carbon blending amount of 30 parts and a member thickness of 10 mm, has a glass transition temperature Tg of about 30 ° C. and a JIS / A hardness of 30. is there. As a result of the vibration absorption characteristic experiment of this material, the vibration attenuation level is 10 dB or more at an excitation frequency of 5 Hz, the vibration attenuation level is 3 to 10 dB at an excitation frequency of 50 Hz, and the excitation frequencies are 500 Hz, 3000 Hz, and 10 kHz. At 50 kHz, the vibration attenuation level was 3 dB or less.

  Example 5 uses a styrene-butadiene block copolymer (SBS) as a polymer material, has a carbon thickness of 10 mm, and has a glass transition temperature Tg of about −40 ° C., JIS / A hardness. Is 45. As a result of the vibration absorption characteristic experiment of this material, the vibration attenuation level is 3 dB or less at the excitation frequency of 5 Hz, 50 Hz, 500 Hz, the vibration attenuation level is 3 to 10 dB at the excitation frequency of 3000 Hz, 10 kHz, and the excitation frequency. However, the vibration attenuation level was 3 dB or less at 50 kHz.

  In Comparative Example 1, butyl rubber (IIR) was used as the polymer material, the carbon content was 50 parts, and the member thickness was 10 mm. The glass transition temperature Tg was about −35 ° C., and the JIS / A hardness was 62. is there. As a result of the vibration absorption characteristic experiment of this material, the vibration attenuation level is 3 dB or less at an excitation frequency of 5 Hz, 50 Hz, and 500 Hz, the vibration attenuation level is 3 to 10 dB at an excitation frequency of 3000 Hz, and the excitation frequency is 10 kHz. At 50 kHz, the vibration attenuation level was 3 dB or less.

  In Comparative Example 2, butyl rubber (IIR) was used as the polymer material, the carbon content was 30 parts, and the member thickness was 0.3 mm. The glass transition temperature Tg was about −35 ° C., and the JIS / A hardness was 45. As a result of the vibration absorption characteristic experiment of this material, the vibration attenuation level is 3 dB or less at an excitation frequency of 5 Hz, 50 Hz, and 500 Hz, the vibration attenuation level is 3 to 10 dB at an excitation frequency of 3000 Hz, and the excitation frequency is 10 kHz. At 50 kHz, the vibration attenuation level was 3 dB or less.

  As described above, in Examples 1 to 5, high-frequency vibrations are absorbed if the glass transition temperature Tg of each polymer material is low, and low-frequency vibrations are absorbed if the glass transition temperature Tg is low. It can be seen that a desired filter effect is obtained. In particular, the butyl rubber of Example 3 has a large loss inherent to the polymer material, so that a particularly good vibration absorbing effect can be obtained.

  Further, in Comparative Example 1, it is understood that the vibration absorption effect is small because the polymer material has a JIS · A hardness of the polymer material higher than a value within the preferred range.

  Moreover, in the comparative example 2, since the interposed member whose member thickness is thinner than the value within a suitable range was used, it turns out that the vibration absorption effect is small.

  Next, a second embodiment of the present invention will be described.

  FIG. 3 is a view showing a sensor mounting structure according to the second embodiment of the present invention. In the figure, the same components as those in the first embodiment are denoted by the same reference numerals, and the description thereof is omitted.

  In the second embodiment, the sensor 20B having the case 21B made of the same polymer material as in the first embodiment is provided, and the interposition member 30 is removed. Further, the bottom surface of the case 21 </ b> B is adhered to the surface of the measurement object 10, and the sensor 20 </ b> B is fixed to the measurement object 10. Further, the thickness D2 of the bottom surface of the case 21B is set to 0.5 mm.

  Thus, even if the case 21B of the sensor 20B is formed of the above-described polymer material, the vibration generated in the measurement object 10 such as a machine or a vehicle is measured by the sensor 20B having the sensor body 22 such as an acceleration sensor or a vibration sensor. In this case, since the sensor 20B is attached to the measurement object 10 via the case 21B made of a polymer material having vibration absorption characteristics near the resonance frequency of the sensor 20B, any part of the measurement object 10 is attached. Since it can be easily attached to, it is not subject to restrictions on the attachment location. Further, since the vibration of the resonance frequency input to the sensor 20B (sensor body 22) is effectively cut off by the case 21B, the adverse effects due to the resonance can be eliminated, and accurate measurement can be performed.

  In the present embodiment, the entire case 21B is formed of the polymer material. However, even if at least a part of the case 21B, that is, only a portion that contacts the measurement object 10 is formed of the polymer material, Similar effects can be obtained.

  Next, a third embodiment of the present invention will be described.

  FIG. 4 is a view showing a sensor mounting structure according to a third embodiment of the present invention. In the figure, the same components as those in the first embodiment are denoted by the same reference numerals, and the description thereof is omitted.

  In the third embodiment, the sensor 20 </ b> C from which the case 21 in the first embodiment is removed is attached to the measurement object 10 via the interposed member 30. That is, the bottom surface of the support member 24 of the sensor 20 </ b> C is bonded to the upper surface of the interposed member 30, and the lower surface of the interposed member 30 is bonded to the surface of the measurement object 10.

  Even if the sensor 20C having no case is fixed to the measurement object 10 with the intervening member 30 made of the polymer material interposed therebetween, the sensor 20C having the sensor body 22 such as an acceleration sensor or a vibration sensor can When measuring the vibration generated in the measurement object 10 such as a vehicle, the sensor 20C is adhered to the measurement object 10 via the interposition member 30 made of a polymer material having vibration absorption characteristics near the resonance frequency of the sensor 20C. Since it is attached, it can be easily attached to an arbitrary location of the measurement object 10, so that there is no restriction on the attachment location. Furthermore, since the vibration of the resonance frequency input to the sensor 20C is effectively cut off by the interposition member 30, the harmful effects due to resonance can be eliminated, and accurate measurement can be performed.

  Next, a fourth embodiment of the present invention will be described.

  FIG. 5 is a view showing a sensor mounting structure according to a fourth embodiment of the present invention. In the figure, the same components as those in the first embodiment are denoted by the same reference numerals, and the description thereof is omitted.

  In the fourth embodiment, the case 21 in the first embodiment is removed, and the sensor 20D including the support member 24B made of the polymer material is attached to the measurement object 10. That is, the sensor 20D includes a sensor substrate 23 in which a sensor main body 22 made of a vibration sensor or an acceleration sensor is soldered to the upper surface, and the lower surface of the sensor substrate 23 has a plurality of support members 24B made of the polymer material. The upper surface is bonded, and the lower surface of the support member 24B is bonded to the surface of the measurement object 10. Thereby, the sensor 22D is fixed to the measurement object 10.

  Thus, even if the sensor substrate 23 of the sensor 20D is fixed to the measurement object 10 by the support member 24B made of the polymer material, the sensor 20D having the sensor main body 22 such as an acceleration sensor or a vibration sensor can be used for a machine or a vehicle. When measuring the vibration generated in the measurement object 10, the sensor 20D is attached to the measurement object 10 via a support member 24B made of a polymer material having vibration absorption characteristics near the resonance frequency of the sensor 20D. Therefore, since it can be easily attached to an arbitrary portion of the measurement object 10, there is no restriction on the attachment portion. Furthermore, since the vibration of the resonance frequency input to the sensor 20D is effectively cut off by the support member 24B, the harmful effects due to resonance can be eliminated, and accurate measurement can be performed.

The figure which shows the sensor attachment structure of 1st Embodiment of this invention. The figure explaining the Example of the polymeric material in 1st Embodiment of this invention The figure which shows the sensor attachment structure of 2nd Embodiment of this invention. The figure which shows the sensor attachment structure of 3rd Embodiment of this invention. The figure which shows the sensor attachment structure of 4th Embodiment of this invention.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10 ... Measurement object, 20, 20B, 20C, 20D ... Sensor, 21, 21B ... Case, 22 ... Sensor main body, 23 ... Sensor substrate, 24, 24B ... Support member, 30 ... Interposition member.

Claims (6)

In a sensor mounting structure for mounting a sensor for measuring vibration generated on a measurement object to the measurement object,
A member made of a polymer material having a glass transition temperature (Tg) obtained by a temperature-frequency conversion rule within a predetermined frequency band including a resonance frequency of the sensor is attached to the sensor, and the sensor and the measurement A sensor mounting structure, characterized in that a member made of the polymer material is interposed between objects and bonded to the object to be measured. The sensor mounting structure according to claim 1, wherein a thickness of the member made of the polymer material is set to a value within a range of 0.5 mm to 30 mm.   3. The sensor mounting structure according to claim 1, wherein the polymer material has a JIS · A hardness within a range of 30 to 60. 4.   The sensor mounting structure according to any one of claims 1 to 3, wherein a part or all of the case of the sensor is formed of the polymer material.   The sensor attachment structure according to any one of claims 1 to 4, wherein a loss coefficient tanδ at 25 ° C of the polymer material is 0.3 or less.   The sensor attachment structure according to any one of claims 1 to 4, wherein a loss coefficient tanδ at 25 ° C of the polymer material is 0.2 or less.

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