CN2329969Y

CN2329969Y - Heat insulation combined sleeve for high-temp. (400 deg.C) piezo-accelerometer

Info

Publication number: CN2329969Y
Application number: CN 98224170
Authority: CN
Inventors: 胡子俭; 李毅; 李承恩; 倪焕尧; 王志超; 鲍军; 张秀荣; 贺连星
Original assignee: Shanghai Institute of Ceramics of CAS
Current assignee: Shanghai Institute of Ceramics of CAS
Priority date: 1998-06-01
Filing date: 1998-06-01
Publication date: 1999-07-21
Anticipated expiration: 2008-06-01

Abstract

The utility model relates to a heat insulation combined sleeve pipe for high-temp. (400 DEG C) piezoelectric accelerometers, which belongs to the field of the high temperature vibration sensor. The heat insulation combined sleeve pipe provided by the utility model is composed of an upper and a lower blocks of pads 7 and a sleeve pipe 8, and made of heat-resistant ceramic material. The thickness and the wall thickness are reduced with the reduction of the thermal conductivity of manufacture material. When the utility model is put on a piezoelectric accelerometer bottom seat, the measuring accuracy can be improved, and the application temperature range is widened. The utility model has simple structure, easy processing and convenient operation.

Description

The heat insulation assembled casing of high temperature (400 ℃) piezoelectric accelerometer

The utility model relates to the heat insulation assembled casing of a kind of high temperature (400 ℃) piezoelectric accelerometer, belongs to the high temperature oscillation sensor field.

Vibration is modern various engineering, as the important parameter in the various structural designs of guided missile, aircraft, boats and ships, automobile, bridge and even dykes and dams and dam buildings.With the guided missile is example, show according to U.S. statistics in the sixties, and the destruction of Chu Xianing awing, wherein half is because the reason of vibrating causes.Therefore countries in the world are extremely paid close attention to the vibrational structure parameter, design and made various types of vibration-measuring sensors, in order to determine the equivalent load of dynamic environment.

In various types of vibration-measuring sensors, piezoelectric accelerometer because of it has that size is little, in light weight, wide frequency range (3～20, advantage and be subjected to widespread use such as 000Hz).Accelerometer always is in the working environment of harshness (light, temperature, noise, strain), actual utilization structure is all complicated, on material is selected, should also be noted that the pyroelectric effect of material except that considering piezoelectric modulus size and stability, this is because sensing element-ferroelectric material permanently-polarised intensity of using as piezoelectric accelerometer changes with temperature.Working method not simultaneously, the charge signal that same material produces under uniform temp changes is different.No matter be general compression-type, single-ended compression-type, isolate compression and anticentre compression-type and shearing-type accelerometer, the stability that all should be taken into account the piezoelectric sensor environment temperature is with degree of accuracy that guarantees vibration and the usable range of widening piezoelectric accelerometer.In existing piezoelectric accelerometer structure, the high-temperature piezoelectric ceramic component directly with sensor base with hold out against screw and contact, the temperature of base directly passes on the high temperature sensitive element, cause the working temperature of high-temperature piezoelectric ceramic component to influence with pedestal, thereby measuring accuracy is affected, causes the serviceability temperature scope of piezo ceramic element to narrow down.Fig. 1 is general high-temperature piezoelectric arrangements of accelerometers figure, 1-housing among the figure; 2-holds out against screw; The 3-mass; The 4-piezo ceramic element; The 5-sensor base; 6-exports connector.Can be clear that sensor base 5 and hold out against screw 2 and directly contact from figure with piezoelectric sensor.

The purpose of this utility model is to provide the assembled casing of a special construction, be placed on the sensor base with it, make the pyrostat element directly with base with hold out against screw and contact, can avoid from sensor base and the direct influence that holds out against the screw temperature variation, thereby improve accelerometer serviceability temperature scope and accuracy of detection.

Specifically, the heat insulation assembled casing that provides of the utility model as shown in Figure 2.7 is pad among Fig. 2-1, parallel and the flatness of both ends of the surface is＜0.03mm gets final product, 8 is sleeve pipe, there is hole, a garden in pad 7 central authorities, the external diameter that its size just is being better than sleeve pipe 8 is complementary, and the wall thickness of sleeve pipe 8 is generally 0.4～2mm, and endoporus central authorities allow to hold out against screw 2 and pass through, its internal diameter matches with holding out against screw 2 diameters, and the gap is 0.05-0.1mm.Assembled casing 9 (Fig. 2-2) is to be combined by two pads 7 and a sleeve pipe 8, and the thickness of pad 7 is generally 0.5～2mm, and diameter is suitable with the piezoelectric element diameter.The endoporus central authorities of sleeve pipe 8 hold out against screw 2, and in both gap allowed bands, the gap is 0.05～0.5mm scope between outside surface and the piezoelectric ceramic piece.Pad 7 and sleeve pipe 8 are made by the low heatproof pottery of coefficient of heat conductivity, as various components (75 porcelain, 85 porcelain, 90 porcelain, 95 porcelain, 99 porcelain) aluminium oxide, mullite, silicon nitride and clay material; The value of wall thickness is relevant with the thermal conductivity coefficient of making material, and wall thickness can be corresponding little when the material that coefficient of heat conductivity is low was made, otherwise wall thickness is bigger.

The heat insulation assembled casing that the utility model provides has simple in structure, easily processing, cost is low, only needs general ceramic preparation method moulding, sintering, and the effect after using is fairly obvious, and it can make high temp sensitive element working environment avoid the sensor base heat effects and improve measuring accuracy.

The embodiment that uses as the utility model as shown in Figure 3, content among the figure shown in 1～9 and Fig. 1, Fig. 2 is identical, heat insulation assembled casing 9 is placed on seal shadow position shown in Figure 3, piezo ceramic element 4 directly with sensor base 5 with hold out against screw 2 and contact, pad 7 and sleeve pipe 8 are made by 90 alumina materials, the thickness of pad 7 is 1mm, the sleeve wall thickness is 0.5mm, tolerance is a free tolerance, the combined sleeve lower cushion block contacts with sensor base 5, and last cushion block contacts with mass 3, combines with metal adhesive with general commercially available pottery between them, sleeve 8 outside surfaces and piezo ceramic element leave for 0.3mm, inwall and hold out against hole 0.08mm between the screw 2.

Claims

1. heat insulation assembled casing that the high-temperature piezoelectric accelerometer is used is characterized in that:

(1) heat insulation assembled casing by up and down two form;

(2) pad (7) and sleeve pipe (8) are made by heat resisting ceramic materials;

(3) heat insulation assembled casing is placed in above the sensor base (5), Upper gasket contacts with mass (3), lower gasket contacts with sensor base (5), and sleeve pipe (8) endoporus central authorities allow to hold out against screw (2) and pass through, and the gap is 0.05-0.5mm between outside surface and the piezo ceramic element (4);

(4) combine with metal adhesive with pottery between pad (7) and mass (3) and the pedestal (5).

2. by the described heat insulation combined sleeve of claim 1, it is characterized in that described pad (7) and sleeve (8) made by various components (75 porcelain, 85 porcelain, 90 porcelain, 95 porcelain, 99 porcelain) aluminium oxide, mullite, silicon nitride and clay material.

3. by the described heat insulation combined sleeve of claim 1, it is characterized in that described pad (7) diameter is suitable with the piezoelectric sensor diameter, thickness is 0.5～2mm, reduces with the pyroconductivity of making heat-stable ceramic to reduce.

4. by the described heat insulation combined sleeve of claim 1, it is characterized in that the wall thickness of described sleeve (8), also the pyroconductivity with the heat-stable ceramic that uses reduces and attenuate, and the scope of wall thickness is 0.4～2mm.