JPH07218332A - Piezoelectric type vibration sensor apparatus - Google Patents

Abstract

PURPOSE:To provide a piezoelectric type vibration sensor capable of measuring a wide range of frequency, excellent in temp. characteristics and having waterproofness. CONSTITUTION:In a piezoelectric type vibration sensor apparatus wherein a piezoelectric type vibration sensor 35 constituted by attaching a load member 46 to a detection part 45 wherein electrodes are fixed to both surfaces of a piezoelectric element 43 and supports 44 are fixed on both sides thereof and a signal processing circuit board 36 are received in a package 33, the package 33 is constituted of a housing 31 made of a conductive substance having a recessed part 34 housing the piezoelectric type vibration sensor 35 formed thereto and a housing lid member 32 composed of a conductive substance covering the opening part of the recessed part 34. The load member 46 of the piezoelectric type vibration sensor 35 is bonded to the bottom part of the housing 31 toward the opening part of the recessed part 3 of the housing 31. Further, the signal processing circuit board 36 is stretched over the peripheral edge part 37 of the opening part of the housing 31 to be covered with the housing lid member 32 and the housing lid member 33 is integrated with the housing 31.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a piezoelectric vibration sensor device having a piezoelectric vibration sensor housed in a package, and more particularly to a piezoelectric vibration sensor device having excellent temperature characteristics and waterproofness.

[0002]

2. Description of the Related Art FIG. 5 shows a conventional piezoelectric vibration sensor device.
The structure shown in is proposed. This is a package 3 having conductivity, which is composed of a housing 1 and a housing cover 2.
The piezoelectric vibration sensor 5 is housed in the recess 4 formed in the housing 1, and the signal processing circuit board 6 is attached to the piezoelectric vibration sensor 5 so that the periphery of the opening of the housing 1 is It is supported in part 7. Further, the housing cover 2 covers the signal processing circuit board 6.
Is configured to be fitted on the opening side of the concave portion 4 of the storage body 1.

Here, when the housing 1 side of the package 3 constituting the piezoelectric vibration sensor device 8 is the lower side and the housing cover 2 side is the upper side, the cable outlet 10 is provided on the upper surface 9 of the housing cover. A connector is attached to the cable outlet 10, and the receptacle 11 of the connector is provided.
Thus, the pulled-out power supply line 12 is connected to the signal processing circuit board 6. Therefore, the receptacle 11
By inserting the plug 14 to which the connection cable 13 is connected, the piezoelectric vibration sensor 5 having the above-mentioned configuration is
Power is supplied by the power supply line 12, and a signal is output to the outside by the power supply line 12.

Further, in the piezoelectric vibration sensor 5, electrodes (not shown) are fixed on both surfaces of the piezoelectric body 15 via adhesive layers (not shown), and a support plate is formed on both surfaces of the electrodes via adhesive layers. 16 is provided with a detection unit 17 and a load body 18 laminated on the detection unit 17, and the piezoelectric vibration sensor 5 is provided on a surface opposite to the load body 18 provided on the detection unit 17. It is fixed by the attached signal processing circuit board 6. On the surface of the signal processing circuit board 6 on which the electric circuit is mounted, a temperature compensating element 19 for temperature compensating the output from the detecting section 17 is provided.

Further, this is orthogonal to the piezoelectric body 15,
An axis passing through the center of the load body 18 is a vibration sensing axis G1. In such a piezoelectric vibration sensor 5, by mounting an object to be measured on the bottom surface 20 of the housing 1 of the package 3, it is possible to measure a vibration change in the direction of the sensing axis G1 of the object to be measured. Further, when the object to be measured is attached to the upper surface 9 of the storage cover, it is necessary to provide the cable outlet 10 in a place other than the upper surface 9 of the storage cover.

However, in the piezoelectric type vibration sensor device 8, since the piezoelectric type vibration sensor 5 is hung on the signal processing circuit board 6, the weight of the piezoelectric type vibration sensor 5 causes the signal processing circuit board 6 to move. When measuring flexure and vibration, there is a problem that the flexure portion resonates with a specific vibration, which may cause a measurement error. Such a problem can be solved by increasing the thickness and elastic modulus of the signal processing circuit board 6.
However, as a material that satisfies these conditions,
For example, ceramics and the like are expensive, and as a result, the manufacturing cost of the piezoelectric vibration sensor device 8 is high, and there is a problem in that the piezoelectric vibration sensor device 8 needs to be upsized. Further, in the piezoelectric vibration sensor device 8 having such a structure, there is a possibility that moisture or moisture may enter from a gap between the connection cable 13 and the housing cover 2 or a joint portion between the housing 1 and the housing cover 2. However, there are also problems such as unsuitability when waterproofness is required, such as for diagnosis of rotating or vibrating equipment.

[0007]

SUMMARY OF THE INVENTION The present invention has been made in view of these circumstances, and it is possible to measure a wide range of frequencies, a piezoelectric type having excellent temperature characteristics and waterproofness. An object is to provide a vibration sensor device.

[0008]

The object is to fix the electrodes through the adhesive layers provided on both sides of the piezoelectric body, and to attach the load body to the detection section in which the supports are fixed on both sides thereof. In a piezoelectric vibration sensor device in which a piezoelectric vibration sensor and a signal processing circuit board are housed in a package, a container made of a conductive material in which a recess for housing the piezoelectric vibration sensor is formed in the package, And a storage cover made of a conductive material that covers the opening of the recess, and the load body of the piezoelectric vibration sensor is bonded to the bottom of the storage body so as to face the opening of the recess of the storage body. The signal processing circuit board is joined to each other via a layer, the signal processing circuit board is bridged over the peripheral portion of the opening of the housing, and the housing cover and the housing are integrated so as to cover the signal processing circuit board. Can be solved by . Further, it is preferable that the thermal conductivity of the container is 0.4 cal / cm / s / K or less, and the wall thickness of the container is 1 mm or more. Furthermore, the elastic modulus is 1 × 10 ⁶ to between the piezoelectric vibration sensor device and the housing.
It is preferable to form an adhesive layer having a thickness of 1 × 10 ⁹ Pa and a thickness of 5 to 100 μm. Further, the piezoelectric vibration sensor may be joined to the housing body via a spacer having a roughly plate shape. At this time, it is preferable to form an adhesive layer having the same elastic modulus and thickness as the adhesive layer between the piezoelectric vibration sensor and the spacer, and between the spacer and the housing. Furthermore, it is preferable to fill a part or all of the void formed by the signal processing circuit board and the housing cover with resin.

[0009]

The piezoelectric vibration sensor device of the present invention uses a material having a wall thickness of 1 mm or more and a thermal conductivity of 0.4 cal / cm / s / K or less. The temperature change inside the package that constitutes the piezoelectric vibration sensor device becomes smaller with respect to the ambient temperature change. Furthermore, the adhesive layer formed between the piezoelectric vibration sensor and the housing has an elastic modulus of 1 × 10 ⁶ to 1 × 10 ⁹ Pa and a thickness of the adhesive layer of 5 to 100 μm. The distortion of the support plate due to the difference between the thermal expansion coefficient of the housing and the thermal expansion coefficient of the support plate forming the piezoelectric vibration sensor is absorbed by the adhesive layer, and a high resonance frequency is also obtained. Further, when the piezoelectric vibration sensor and the housing are joined via a spacer having a specific coefficient of thermal expansion, the support plate constituting the piezoelectric vibration sensor and the supporting plate due to the difference in the thermal expansion coefficient of the housing. The distortion of can be relaxed. Further, when the cable end portion is located in the void formed by the signal processing circuit board and the housing cover, by filling the void with resin, the gap between the cable and the housing cover is filled. Therefore, infiltration of moisture and humidity does not occur.

[0010]

EXAMPLES Next, the piezoelectric vibration sensor device of the present invention will be described in detail. As shown in FIG. 1, the piezoelectric vibration sensor device 30 of the present invention includes a housing 31 of a package 33 having a conductive property, which includes a housing 31 and a housing cover 32.
The piezoelectric vibration sensor 35 is housed in the concave portion 34 formed in. Further, the signal processing circuit board 36
Are supported by the peripheral edge portion 37 of the opening of the storage body 31. The housing cover 32 is fitted to the signal processing circuit board 36 so as to fit on the opening side of the recess 34 of the housing 31.

When the housing 31 side of the package 33 constituting the piezoelectric vibration sensor device 30 is the lower side and the housing cover 32 side is the upper side, the cable outlet 38 is provided on the upper surface 32a of the housing cover. A connector is attached to the cable outlet 38, and the power supply line 40 drawn from the receptacle 39 of the connector is connected to the signal processing circuit board 36. Therefore, the plug 4 in which the cable 41 is connected to the receptacle 39
2 by inserting the piezoelectric vibration sensor 35.
Is supplied with power by the power supply line 40, and a signal is output to the outside by the power supply line 40. Also,
In the present embodiment, the cable outlet 38 is provided on the storage cover upper surface 32a, but it may be provided not only on the storage cover 32a upper surface but also on the side surface of the package 33 or the like depending on the use application.

In the piezoelectric vibration sensor 35, electrodes (not shown) are formed on both surfaces of the piezoelectric body 43, and a detection unit 45 in which a support plate 44 is laminated on both surfaces of the electrode and the detection unit 45. The load body 46 is laminated.
The piezoelectric vibration sensor 35 is bonded to the bottom of the recess 34 of the housing 31 with an adhesive layer 47 with the load body 46 facing the opening of the recess 34.

As a material for forming the housing 31 and the housing cover 32 which constitute the piezoelectric vibration sensor device 30 as described above, the material has a conductivity of 0.4 cal / cm / s / K or less. If it is a material, the kind is not particularly limited, and for example, stainless steel, fiber reinforced plastic or the like can be used. Furthermore, it is preferable that the thickness of the container 31 is 1 mm or more. This is because when the thermal conductivity is 0.4 cal / cm / s / K or more or the wall thickness is 1 mm or less, the heat insulating property of the package 33 becomes poor and the package 3
This is because it is insufficient to keep the temperature in 3 constant.

The piezoelectric vibration sensor 35 and the housing 31 are also provided.
The adhesive layer 47 formed by applying the adhesive has an elastic modulus of 1 × 10 ⁶ to 1 × 10.
⁹ Pa, and the thickness of the adhesive layer 47 is 5 to 100 μ
It is preferably m. This is because when the elastic modulus of the adhesive layer 47 is 1 × 10 ⁶ Pa or less, the adhesive layer 47 becomes too soft and it is difficult to obtain a high resonance frequency, and thus the measurable frequency range is narrowed. 1 x 10 ⁹
If it is Pa or more, it becomes too hard to absorb the strain of the support plate 44 due to the difference between the thermal expansion coefficient of the container 31 and the thermal expansion coefficient of the support plate 44. Further, if the thickness of the adhesive layer 47 is 5 μm or less, it is insufficient to absorb the strain of the support plate 44, and if it is 100 μm or more,
This is because a high resonance frequency cannot be obtained.

The piezoelectric type vibration sensor device 30 having the above structure is
The piezoelectric body 43 is orthogonal to the surface on which the electrodes are formed, and the load body 46
The axis passing through the center of is the vibration sensing axis G2. Therefore, in the piezoelectric vibration sensor device 30 as described above, the vibration of the measurement object in the sensing axis G2 direction can be measured by mounting the measurement object on the bottom surface 31a of the housing of the package 33. In addition, the object to be measured is housed in the upper surface 32a
When it is attached to the storage cover, it is necessary to provide the cable outlet 38 in a place other than the upper surface 32a of the storage cover.

The piezoelectric vibration sensor device 30 as described above is
Piezoelectric vibration sensor 35 has a thermal conductivity of 0.4 cal / cm / s / K
Since it is contained in the container 31 having a thickness of 1 mm or more, the heat transfer due to the temperature difference between the inside and the outside of the package 33 constituting the piezoelectric vibration sensor device 30 is small,
Since the temperature change inside the package 33 can be suppressed to be small with respect to the temperature change around the piezoelectric type vibration sensor device 30, the pyroelectric noise due to the temperature change around the piezoelectric type vibration sensor device 30 is reduced, and the sensitivity is reduced. Can be kept good.

Further, the piezoelectric vibration sensor 35 and the housing 3
1 and the elastic modulus is 1 × 10 ⁶ to 1 × 10 ⁹ Pa,
Since the adhesive layer 47 having a thickness of 5 to 100 μm is formed, a high resonance frequency is obtained, and the thermal expansion coefficient of the housing 31 and the thermal expansion coefficient of the support plate 44 constituting the piezoelectric vibration sensor 35 are different. Since the strain of the support plate 44 is absorbed by the adhesive layer 47, the temperature characteristic becomes good.

Further, since the piezoelectric type vibration sensor 35 is directly joined to the bottom of the housing 31, the signal processing circuit board 36 does not bend due to the weight of the piezoelectric type vibration sensor 35. Since the signal processing circuit board 36 can be thinly manufactured without using a high-priced material, the manufacturing cost of the piezoelectric vibration sensor device 30 can be reduced.

As a second example of the piezoelectric vibration sensor device of the present invention, FIG. 2 shows an example in which the temperature characteristics of the piezoelectric vibration sensor device 30 described above are further improved. This is the first example except that the piezoelectric vibration sensor 45 is bonded to the plate-shaped spacer 49 via the adhesive layer 48, and the spacer 49 is bonded to the housing 31 via the adhesive layer 48. It is the same as the piezoelectric type vibration sensor device 30.

As a material for the spacer 49, the coefficient of thermal expansion is lower than the higher one of the coefficient of thermal expansion of the support plate 44 of the piezoelectric vibration sensor 35 and the coefficient of thermal expansion of the housing 31. The type is not particularly limited as long as it is higher than the lower one, and for example, a brass plate, a glass fiber reinforced epoxy plate or the like can be used. Further, the piezoelectric vibration sensor 35, the spacer 49, and the spacer 4
The elastic modulus of the adhesive layer 48 between the container 9 and the container 31 is 1 × 10.
⁶ to 1 × 10 ⁹ Pa, and the thickness of the adhesive layer 48 is 5 to 100
It is preferably μm. This is because of the same reason as the piezoelectric vibration sensor device 30 of the first example.

The piezoelectric type vibration sensor device 50 as described above is
The piezoelectric vibration sensor 35 and the housing 31 are joined via a spacer 49 having a roughly plate shape, and the thermal expansion coefficient of the spacer 49 is equal to that of the support plate 44 constituting the piezoelectric vibration sensor 35. Of the coefficient of thermal expansion and the coefficient of thermal expansion of the container 31,
If it is lower than the higher one and higher than the lower one, the strain of the support plate 44 due to the difference between the thermal expansion coefficient of the housing body 31 and the thermal expansion coefficient of the support body 44 can be alleviated, so that the external temperature change can be prevented. The distortion of the support plate 44 is suppressed, and the temperature characteristics can be further improved. In addition, the adhesive layer 48
Has a modulus of elasticity of 1 × 10 ⁹ Pa or less and a thickness of 5 μm or more, the support plate 44 due to the difference between the coefficient of thermal expansion of the container 31 and the coefficient of thermal expansion of the support plate 44 constituting the piezoelectric vibration sensor 35. Since the strain is absorbed by the adhesive layer 48, the piezoelectric vibration sensor device 50 having better temperature characteristics is obtained. Furthermore, peeling of the adhesive caused by the difference in thermal expansion when a thermal history phenomenon occurs can be prevented, and defective points can be reduced. Further, even if a resin package having a large coefficient of thermal expansion is used, the temperature characteristics are not impaired, and thus cost reduction can be expected. Further, since the adhesive layer 48 has an elastic modulus of 1 × 10 ⁶ Pa or more and a thickness of 100 μm or less, a high resonance frequency can be obtained and the measurable frequency range is widened.

The first piezoelectric vibration sensor device 30,
In the second piezoelectric vibration sensor device 50, the cable end portion is located in the space 51 formed by the signal processing circuit board 36 and the housing cover 32.
Waterproofing can be imparted by filling a part of the void 51 with a resin. As the resin, those having low electric conductivity such as epoxy type and silicon type are preferable. Further, among the resins, the signal processing circuit board 3
6 and the components constituting the signal processing circuit board 36 are close to each other in thermal expansion coefficient, and the adhesiveness between the housing cover 32 and the cable 41 is preferable.

The resin is preferably filled so as to fill the gap between the cable 41 and the housing cover 32. In addition, it is preferable to fill 20% to 100% of the space 51 with resin. This is because if it is 20% or less, moisture or water may reach the signal processing circuit board 36 and the stress applied to the cable 41 is insufficient.

Such piezoelectric type vibration sensor devices 30, 5
0 indicates that the cable end portion is located in the void portion 51 formed by the signal processing circuit board 36 and the housing cover 32, and the resin is filled in a portion of the void portion 51. Since moisture and humidity are prevented from entering through the gap between the cover 41 and the housing cover 32, the probability of failure at the time of flooding is reduced, and the stress applied to the cable 41 is alleviated, so that the piezoelectric vibration sensor device 30 is provided. , 50 can be improved in mechanical strength.

Next, the piezoelectric vibration sensor device 3 of the present invention.
Manufacturing examples of 0 and 50 will be described below. (Manufacturing Example) In this manufacturing example, the piezoelectric vibration sensor device 30 having the structure shown in FIG. 1 was manufactured. First, 5mm square,
An epoxy adhesive is applied to both surfaces of a piezoelectric body 43 made of PZT (lead zirconate titanate) having a thickness of 0.5 mm, and the same size as the piezoelectric body 43 is applied onto the adhesive.
A 0 μm thick copper foil was laminated and adhered. This copper foil is used as an electrode. Then, apply epoxy adhesive on both sides of the copper foil, and further apply 1 mm thick, 15 m
A support plate 44 made of an m-square glass epoxy plate was laminated and adhered. In this way, the detection unit 45 of the piezoelectric vibration sensor 35 was produced. Then, an adhesive similar to the adhesive is applied to one surface of the detection unit 45, and a brass load body 46 having a weight of 1 g is laminated and adhered on the adhesive.
The piezoelectric vibration sensor 35 is used.

Further, an adhesive is applied to the detecting portion 45 on the side where the load body 46 is not laminated to form an adhesive layer 47,
The piezoelectric vibration sensor 35 has an outer diameter 25 having a recess 34.
After being housed in the recess 34 of the housing 31 having a height of 10 mm and a height of 10 mm, the piezoelectric vibration sensor 35 was bonded to the bottom of the housing 31 via the adhesive layer 47. Further, the signal processing circuit board 36 is installed by being hung over the peripheral edge portion 37 of the opening of the housing 31, and then the housing cover 32 is installed so as to cover the signal processing circuit board 36, and the housing cover is installed. 32 and the storage body 31 are integrated.

On the other hand, a cable outlet 38 is provided in advance on the upper surface 32a of the storage cover, a connector is installed in the cable outlet 38, and the power supply line 40 drawn out from the receptacle 39 of the connector is subjected to the signal processing. It was connected to the circuit board 36. Thus, the piezoelectric vibration sensor device 30 having the structure shown in FIG. 1 was obtained.

Next, the following measurement test is conducted to clarify the effect of the present invention. First, with respect to the piezoelectric vibration sensor devices having a total of 11 test bodies of Examples 1 and 2 and Comparative Examples 1 to 9 having the characteristics shown in Table 1, measurement tests of the following Test Examples 1 to 3 were performed. went. Example 1 and Example 2 are examples of the above-described manufacturing example. In Example 1 and Example 2, the elastic modulus and the thickness of the adhesive layer 47 formed between the support plate 44 and the housing 31 are different. It is different. Further, the comparative example has a different structure from the piezoelectric type vibration sensor device of the previous manufacturing example, or the thermal conductivity of the container 31 is 0.4 cal / cm / s / K or less, and Thickness is 1mm
The thickness of the adhesive layer 47 formed between the piezoelectric vibration sensor 35 and the housing 31 is 5 to 100 μm.
Then, at least one or more of the conditions of the present invention that the elastic modulus is 1 × 10 ⁶ to 1 × 10 ⁹ Pa are not satisfied.

The structure A in Table 1 is shown in FIG.
This indicates the structure of the piezoelectric vibration sensor device 30 of the above-described manufacturing example. Further, the structure B refers to the structure shown in FIG. In this case, the signal processing circuit board 36 is joined to the upper inside of the housing 32 and the cable outlet 38 is provided.
Is provided on the side surface of the package 33. Further, the structure C refers to the structure shown in FIG. This is one in which the piezoelectric vibration sensor 35 of the above-described manufacturing example is bonded to the bottom of the housing 31, whereas it is bonded to the top of the signal processing circuit board 36. Therefore, the cable outlet 38 is provided on the side surface of the package 33 and below the signal processing circuit board 36. The structure D is
It refers to the structure shown in FIG. In this device, the piezoelectric vibration sensor 5 of the above-described manufacturing example is suspended on the signal processing circuit board 6 with the load body 18 on the lower side. Further, in Table 1, T1 indicates the wall thickness of the peripheral walls of the storage bodies 1 and 31, and T2 indicates the wall thickness of the bottom. Furthermore, of the materials that form the housings 1 and 31, the thermal conductivity of stainless steel is 0.04 cal / cm.
/ s / K, the thermal conductivity of aluminum is 0.5 cal / cm / s
/ K.

[0030]

[Table 1]

Test Example 1 First, the temperature characteristics of each test body were tested. This is to measure the output when hot air of about 100 ° C. is blown for one second from a distance of 50 cm above the piezoelectric type vibration sensor device at room temperature, and the output is measured at 100 Hz when the ambient temperature of the piezoelectric type vibration sensor device is 25 ° C. This was evaluated as pyroelectric noise by comparing with the output at 1G. The results are shown in Table 2.

(Test Example 2) Next, the measurable frequency range of the piezoelectric vibration sensor device of each test body was tested. this is,
± 20 when voltage output of 100Hz and 1G is set to 1
The frequency within the fluctuation range within% was evaluated as the measurable frequency range. The room temperature during the measurement was adjusted to 25 ° C. The same test specimens as in Test Example 1 and the ones shown in Table 1 were used. The results are shown in Table 2.

(Test Example 3) Next, the measurable temperature range of the piezoelectric vibration sensor device of each test body was tested. This is 100H when the temperature around the piezoelectric vibration sensor device is 25 ° C.
When the output in z and 1G was 1, the temperature within the fluctuation range of ± 20% was evaluated as the measurable temperature range. The same test specimens as in Test Example 1 and the ones shown in Table 1 were used. The results are shown in Table 2.

[0034]

[Table 2]

As described above, the piezoelectric vibration sensor device 30 of the present invention, that of the first and second embodiments, showed good results in pyroelectric noise, measurable frequency range, and measurable temperature range. . On the other hand, the conventional piezoelectric vibration sensor device 8 has a structure, the housings 1 and 31 have a wall thickness of 1 mm or less, and the thermal conductivity of the housings 1 and 31 is 0.4 cal / cm / s / K.
The above, the thickness of the adhesive layer 47 is 5 μm or less, or 100 μm or more, the elastic modulus of the adhesive layer 47 is 1 × 10
Those having a pressure of ⁶ Pa or less or 1 × 10 ⁹ Pa or more were inferior in at least one of pyroelectric noise, measurable frequency range and measurable temperature range.

Next, the temperature characteristics of the piezoelectric vibration sensor device 50 of the second example of the present invention were tested. As the test body, a total of 10 test bodies of Examples 3 to 5 and Comparative Examples 10 to 16 having the characteristics shown in Table 3 were used. The third to fifth embodiments are the piezoelectric type vibration sensor device 50 of the second example of the present invention, and include the container 31 and the spacer 49.
Or the support plate 44 and the spacer 49, which form the piezoelectric vibration sensor 35, and the spacer 49 and the housing 3.
The elastic modulus and the thickness of the adhesive layer 48 formed between the adhesive layer 1 and the adhesive layer 1 are changed.

Further, in Comparative Examples 10 to 16, the spacer 49 is not provided in the piezoelectric vibration sensor device 50 of Examples 3 to 5, or the spacer 49 has a coefficient of thermal expansion of the piezoelectric type. The coefficient of thermal expansion of the support plate 44 and the coefficient of thermal expansion of the housing 31 that constitute the vibration sensor 35 are lower than the higher one and higher than the lower one, or the housing 31 and the spacer 49, the spacer 49 and the support plate. 44 has a thickness of 5 to 100 μm.
In the condition that the elastic modulus is 1 × 10 ⁶ to 1 × 10 ⁹ Pa, at least one or more is not satisfied. Further, the structures of the piezoelectric vibration sensor devices of Examples 3 to 5 and Comparative Examples 12 to 16 are shown in FIG. 2, and the support plate 44 and the housing 31 which constitute the piezoelectric vibration sensor 35. 7mm in length and 7m in width between
m is the same as the previous manufacturing example except that a spacer 49 having a thickness of 1 mm is installed. On the other hand, Comparative Example 10 and Comparative Example 11
The structure of the piezoelectric vibration sensor device is as shown in FIG.
This is the same as the previous manufacturing example.

The spacers 49 of Examples 3 and 12 were made of brass, and the spacers 49 of Examples 4 and 5 and Comparative Examples 13 to 16 were made of aluminum. Furthermore, Example 3 and Comparative Example 10
The storage body 31 of is made of stainless steel,
The container 31 of Comparative Examples 11 to 16 was made of brass fiber reinforced nylon 6. At this time, the container 31 used had a peripheral wall thickness of 2 mm and a bottom wall thickness of 1.5 mm.

The supporting plates 44 constituting the piezoelectric vibration sensor 35 are the same as those used in the above-mentioned manufacturing example, and have a coefficient of thermal expansion of 20 × 10 ^-6 / K. The numerical value of the coefficient of thermal expansion specified in Table 2 is the coefficient of linear thermal expansion.
Further, the support plate 44, the spacer 49, and the spacer 4
The two adhesive layers 48 formed between the container 9 and the container 31 have the same thickness and elastic modulus.

[0040]

[Table 3]

(Test Example 4) Here, the above-mentioned 10 shown in Table 3 was used.
The temperature characteristics of the piezoelectric vibration sensor device of the test body were tested.
This is because the ambient temperature of the piezoelectric vibration sensor device is 25 ° C.
Then, the output at 100 Hz and 1 G is set to 1, and the rate of change in output when the ambient temperature of the piezoelectric vibration sensor device is changed from −30 to 80 ° C. is evaluated. Also, the measurable frequency range was tested in the same manner as in Test Example 2. The results are shown in Table 4.

[0042]

[Table 4]

By comparing Example 4 with Comparative Example 11, it can be seen that the influence on the ambient temperature change is reduced by providing the spacer 49. Further, the piezoelectric vibration sensor device 50 of the present invention provided with the spacer 49 showed good results in the ratio of the output change to the temperature change and the measurable frequency range. On the other hand, without the spacer 49, the thickness of the adhesive layer 48 is 5 μm or less,
Alternatively, the adhesive layer 48 has an elastic modulus of 100 μm or more, the elastic modulus of the adhesive layer 48 is 1 × 10 ⁶ Pa or less, or 1 × 10 ⁹ Pa or more, the thermal expansion coefficient of the spacer 49 is the thermal expansion coefficient of the housing 31, the support plate 44 Among the coefficients of thermal expansion, those higher than the higher coefficient and lower than the lower coefficient were inferior in at least one of the ratio of the output change to the temperature change and the measurable frequency range.

Next, the piezoelectric vibration sensor device 30 of the present invention.
In order to compare the effect of waterproofing by filling the resin of No. 1, the test of the following Test Example 5 was performed. The test bodies used here are three test bodies of Example 6, Example 7, and Comparative Example 17 having the characteristics shown in Table 5. Each of these has the structure shown in FIG. 1 and is similar to the previous manufacturing example. All of the storage bodies 31 were made of stainless steel and had a peripheral wall thickness of 2 mm and a bottom wall thickness of 1.5 mm.

[0045]

[Table 5]

(Test Example 5) Here, the effect of waterproofness by filling the piezoelectric vibration sensor device 30 of the present invention with resin was tested. This is because the void 51 formed between the housing cover 32 and the signal processing circuit board 36 is filled with a silicon-based resin at a ratio shown in Table 5 and immersed in water at a depth of 20 cm for 10 minutes. It can be evaluated by measuring the output after drying the moisture on the surface, and regarding the piezoelectric vibration sensor device 30 that outputs only 50% or less of the initial output as a failure, and examining the failure occurrence rate. The results are shown in Table 6.

[0047]

[Table 6]

As described above, by filling the void portion 51 formed between the housing cover 32 and the signal processing circuit board 36 with the silicone resin, the waterproof property is imparted, and a failure is caused during the inundation. The rate can be significantly reduced.

[0049]

As described above, in the piezoelectric vibration sensor device of the present invention, the electrodes are fixed through the adhesive layers provided on both sides of the piezoelectric body, and the support body is fixed on both sides thereof. In a piezoelectric vibration sensor device in which a piezoelectric vibration sensor having a load body attached thereto and a signal processing circuit board are accommodated in a package, the package has a recess for accommodating the piezoelectric vibration sensor. The formed storage body and the storage cover for covering the storage body, the storage body and the storage cover are made of a conductive material, the storage body has a thermal conductivity of 0.4 cal / cm / s / K or less, and the wall thickness is 1 mm or more, and the piezoelectric vibration sensor is joined to the bottom of the storage body via an adhesive layer so that the load body faces the opening of the recess of the storage body. The processing circuit board is used to open the housing. Supported at the periphery of the mouth, and
Since the housing cover and the housing are integrated so as to cover the signal processing circuit board, the signal processing circuit board does not bend due to the weight of the piezoelectric vibration sensor. Since a material that can be thinly formed and has a low elastic modulus can be used, the manufacturing cost of the piezoelectric vibration sensor device can be reduced.

The heat conductivity of the container is 0.4 cal /
Since the thickness is cm / s / K or less and the thickness of the housing is 1 mm or more, the temperature change inside the package that constitutes the piezoelectric vibration sensor device against the temperature change around the piezoelectric vibration sensor device. Since it is small, pyroelectric noise is reduced. Further, the elastic modulus is 1 × 10 ⁶ to 1 × 10 ⁹ Pa and the thickness is 5 to 100 between the piezoelectric vibration sensor and the housing.
Since the adhesive layer having a thickness of μm is formed, distortion of the supporting plate due to the difference in the coefficient of thermal expansion between the supporting plate that constitutes the piezoelectric vibration sensor and the housing is absorbed by the adhesive layer, so that a high resonance frequency can be obtained. As a result, the measurable frequency range is widened and a wide measurable temperature range can be obtained.

Furthermore, the piezoelectric vibration sensor and the housing are
In the case where the spacers are joined together through the roughly plate-shaped spacer, the coefficient of thermal expansion of the spacer is lower than the higher one of the coefficient of thermal expansion of the support plate and the coefficient of thermal expansion of the housing that constitute the piezoelectric vibration sensor. If it is set higher than the lower one, the strain of the support plate constituting the piezoelectric vibration sensor and the strain of the support plate due to the difference in the thermal expansion coefficient of the housing are alleviated, so that the temperature characteristics are further improved.

Further, in the piezoelectric vibration sensor device in which the cable end portion is arranged in the void portion formed by the signal processing circuit board and the housing cover, the one in which a part of the void portion is filled with resin is , The gap between the cable and the storage cover is filled, and moisture and humidity do not enter inside the package, so the waterproof property is improved and the failure rate during flooding can be significantly reduced. can get.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram showing an embodiment of a piezoelectric vibration sensor device of the present invention.

FIG. 2 is a schematic configuration diagram showing another example of the piezoelectric vibration sensor device of the present invention.

FIG. 3 is a schematic configuration diagram of a piezoelectric vibration sensor device of Comparative Example 1 used in this test example.

FIG. 4 is a schematic configuration diagram of a piezoelectric vibration sensor device of Comparative Example 2 used in this test example.

FIG. 5 is a schematic configuration diagram showing an example of a conventional piezoelectric vibration sensor device.

[Explanation of symbols]

30.50 ... Piezoelectric vibration sensor device, 31 ... Housing, 3
2 ... Storage cover, 33 ... Package, 34 ... Recess, 35 ...
Piezoelectric vibration sensor, 36 ... Signal processing circuit board, 41 ... Cable, 43 ... Piezoelectric body, 44 ... Support plate, 45 ... Detection section,
46 ... Load body, 47/48 ... Adhesive layer, 49 ... Spacer

Claims (5)

[Claims] 1. A piezoelectric vibration sensor in which electrodes are fixed via adhesive layers provided on both sides of a piezoelectric body, and a load body is attached to a detection section in which support bodies are fixed on both sides of the piezoelectric body. In a piezoelectric vibration sensor device in which a signal processing circuit board is housed in a package, the package includes a housing body in which a concave portion for housing the piezoelectric vibration sensor is formed, and a housing cover body that covers the housing body. The storage body and the storage cover are made of a conductive material, the storage body has a thermal conductivity of 0.4 cal / cm / s / K or less, and a wall thickness of 1 mm or more. The sensor is bonded to the bottom of the housing via an adhesive layer so that the load body faces the opening of the recess of the housing, and the signal processing circuit board is provided at a peripheral portion of the opening of the housing. Supported and said signal processing circuit board The piezoelectric vibration sensor device according to housing covering body so as to cover the housing body, characterized in that is formed by integrally. 2. The elastic modulus is 1 × 10 ⁶ to 1 × 10 ⁹ Pa and the thickness is 5 to 10 between the piezoelectric vibration sensor and the housing.
An adhesive layer having a thickness of 0 μm is formed.
The piezoelectric vibration sensor device described. 3. The piezoelectric vibration sensor device according to claim 1, wherein the piezoelectric vibration sensor and the housing are joined via a spacer having a roughly plate shape. 4. An elastic modulus of 1 × 10 ⁶ to 1 × 1 between the spacer and the piezoelectric vibration sensor and between the spacer and the housing.
The piezoelectric vibration sensor device according to claim 3, wherein an adhesive layer having a thickness of 0 ⁹ Pa and a thickness of 5 to 100 µm is formed. 5. The piezoelectric vibration sensor device according to claim 1, wherein a part or all of a void formed by the signal processing circuit board and the housing cover is filled with resin. Type vibration sensor device.