SU759876A1 - Pressure sensor - Google Patents

Description

one

The device relates to a measurement technique, namely, pressure sensors.

Pressure sensors are known that contain a membrane elastic element with a boron-5 tick along the periphery with strain gages located on the membrane [[].

The disadvantage of such sensors is the nonlinearity of the output signal. The closest to the technical essence of this invention is a sensor containing a membrane elastic element with a flange on the periphery attached to the body and a rigid center located at the edges of the flange and the rigid center on the flexible part of the membrane strain gages [2].

A disadvantage of the known device is the low accuracy due to hysteresis and nonlinearity, and 20 also has a narrow measurement range.

The aim of the invention is to expand the range of measured pressures while maintaining linear calibration characteristics. 25

This goal is achieved by the fact that in a known pressure sensor, containing an elastic element in the form of a membrane with a rigid center and a rim on the periphery attached to the housing 30

2

the sensor and strain gauges located at the boundaries of the hard center and the rim are provided with an abutment installed with a gap relative to the hard center, and additional strain tensors. Stores located at a distance of> 0,2,5s | from the borders of the side and · hard center, where ό is the distance between the side and the hard center.

Introduction to the stop sensor allows you to expand the range of measured pressures that the membrane can withstand, while remaining in the area of elastic deformations. At the same time, an additional strain circuit allows measurements in an extended pressure range from zero to pressures at which the stop limits movement of the rigid center of the membrane. Deformations in the membrane are caused by the action of the measured pressure and force on the side of the abutment. The location of the strain gauges of the additional strain gauge in the central region of the flexible part of the membrane ensures its insensitivity to the effect of co-force on the bristle center of the membrane, since the deformations caused by this seat in the center of the flexible part are close to zero.

As a result, the sensitivity is additional "" ". - 3

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the pressure strand of the stringer circuit does not change after being touched by the rigid center of the stop, i.e. the calibration curve remains linear in the extended pressure range.

FIG. 1 shows the sensor, the total volume; in fig. 2 - part of the membrane sensing element with strainer; in FIG., Za, b, c - mounting unit

'' Sensor with diaphragm stop at zero, nominal and above nominal pressure; in fig. 4- dependence of the output signal of both strainer circuits on the applied pressure.

FIG. 1 depicts a membrane

"""" Pressure sensor 1 with a membrane sensing element 2, fastening the side 3 to the attachment point to the housing 4. Above the rigid center 5 of the membrane with a gap there is a 'stop 6.' The required clearance is set by threaded connection of the stop 6 with the housing 20. The constancy of the initial clearance and the tightness of the internal cavity of the sensor is achieved by welding the fence along the perimeter with the housing. The signal from the strain gauges 7–9 is fed to the recording equipment 25. The strain gauge 7 is located at the border of the border and tenzoreeistor 8 - at the border of the hard center gage 9 is in the _center;. membrane area -zd flexible portion at a distance greater than 0.25 of its borders (o / - width of the flexible portion), i.e., from the center and the hard boron ika. '

The sensor works as follows.

When exposed to pressure less

nominal, rigid center is shifted, the strain gauge 7 is experiencing compression deformation, and 8 - stretching.

• The jigging tensor circuit formed by tenp 7 and 8, lying in adjacent shoulders, gives a signal C, pro-40 is proportional to pressure (for simplicity, the other two strain gauges of the bridge "" circuit are not shown). The strain gauge 9 undergoes smaller deformations, therefore the additional strain diagram obrazovannaya 45-type 9 strain gauges,

 those. lying in the central region of the flexible part of the membrane, gives a signal. cash less Q,. but also linearly related to pressure.

For the formation of pavement dotsol ^; tional circuitry can be .ispolzovany tangential resistors raids ------------ d _AlO Suitable sensitivity of opposite sign compared to the radial tenzoreeistorom 9 are as ^ 5

The second radial. The strain gauge of the bridge supplementary circuit is not shown in FIG. Ϊ ... 3 /. At rated

• pressure is touched by a hard center stop. With further increase ¢ 0

. When the pressure is removed, the rigid center remains stationary ·, as it is supported by the abutment, but the flexible part of the pro'® membrane - must be deformed (Fig. Sv). / hook ~ · ...... how "a gesture increases in this touch- ^ 5

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the bone of the membrane, and the further increase in strain of strain gauges 7 and 8 have the same sign (compression), then the output signal C, of the first strain gauge, practically ceases to depend on pressure. Curve and, experiencing at the point of a sharp change.

At the same time, the sensitivity of the additional scheme remains finite, since at P> P _Mop in the central region of the flexible part of the membrane, maximum tensile deformations are achieved (ψΗΓ. _Χ Sv). A sign of the deformation occurs Approximately a quarter of the width of the flexible part of the membrane from its borders (near the border with a rim - compression passes to the maximum extension in the central region of the flexible part to transition to compression near the border with a rigid center).

'The deformation of the membrane is caused by the pressure and force exerted by the abutment applied to the rigid center. In the absence of pressure, when a force is applied to a rigid center, the membrane undergoes deformations of different signs at the rim of the rigid center, and the magnitude of the deformations changes sign in the central region of the flexible part. Strain gages located on the line of zero strains, appearing in the membrane when the force acts on a rigid center, are insensitive to such an effect. Therefore, the calibration characteristic of an additional strain scheme, whose strain gauges are located on the line of zero strains arising in the membrane when a force is applied to a rigid center, is linear over the entire pressure range. The exact location of the zero-strain line in the membrane depends on the ratio of the dimensions of the rigid center and the flexible part and can be found for any particular sizes. In particular, for a very large and very small rigid center, the zero-strain line is located in the center of the flexible part.

Thus, the described sensor allows measurements in the pressure range expanded by comparison with the prototype, while giving a linear output signal. In the range of pressures lower (^^, both strainer circuits can be used; in measurements in the extended pressure range from zero to pressures exceeding Ρ _Ηθ4 , an additional tenoscircuit is used.

Compared to known pressure sensors proposed mnogodiapaEonnymi not ¹ 'requires the presence of several elastic elements. Therefore, its cost, especially when using an integral membrane element, is significantly lower. Compared with the prototype of the proposed sensor has more functionality at the same cost and almost the same complexity.

759876

Claims (1)

Claim Pressure sensor containing an elastic element in the form of a membrane with a rigid center "" ", a rim around the periphery attached to the sensor housing and tenoreeistors located at the boundaries of the hard center and the rim, characterized in that in order to expand the range of measured pressures and improve measurement accuracy it is equipped with a stop set with a gap relative to the rigid center and additional strain gauges located at a distance of 0.25 ° from the border of the rim and the hard center, where is the distance between the rim and the rigid center.