GB2043907A - Differential Pressure Sensor - Google Patents

Differential Pressure Sensor Download PDF

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Publication number
GB2043907A
GB2043907A GB7908180A GB7908180A GB2043907A GB 2043907 A GB2043907 A GB 2043907A GB 7908180 A GB7908180 A GB 7908180A GB 7908180 A GB7908180 A GB 7908180A GB 2043907 A GB2043907 A GB 2043907A
Authority
GB
United Kingdom
Prior art keywords
strain gauges
sensor
cantilever
differential pressure
circuit
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Granted
Application number
GB7908180A
Other versions
GB2043907B (en
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
STC PLC
Original Assignee
Standard Telephone and Cables PLC
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Standard Telephone and Cables PLC filed Critical Standard Telephone and Cables PLC
Priority to GB7908180A priority Critical patent/GB2043907B/en
Publication of GB2043907A publication Critical patent/GB2043907A/en
Application granted granted Critical
Publication of GB2043907B publication Critical patent/GB2043907B/en
Expired legal-status Critical Current

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Classifications

    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01L—MEASURING FORCE, STRESS, TORQUE, WORK, MECHANICAL POWER, MECHANICAL EFFICIENCY, OR FLUID PRESSURE
    • G01L9/00—Measuring steady of quasi-steady pressure of fluid or fluent solid material by electric or magnetic pressure-sensitive elements; Transmitting or indicating the displacement of mechanical pressure-sensitive elements, used to measure the steady or quasi-steady pressure of a fluid or fluent solid material, by electric or magnetic means
    • G01L9/02—Measuring steady of quasi-steady pressure of fluid or fluent solid material by electric or magnetic pressure-sensitive elements; Transmitting or indicating the displacement of mechanical pressure-sensitive elements, used to measure the steady or quasi-steady pressure of a fluid or fluent solid material, by electric or magnetic means by making use of variations in ohmic resistance, e.g. of potentiometers, electric circuits therefor, e.g. bridges, amplifiers or signal conditioning
    • G01L9/04—Measuring steady of quasi-steady pressure of fluid or fluent solid material by electric or magnetic pressure-sensitive elements; Transmitting or indicating the displacement of mechanical pressure-sensitive elements, used to measure the steady or quasi-steady pressure of a fluid or fluent solid material, by electric or magnetic means by making use of variations in ohmic resistance, e.g. of potentiometers, electric circuits therefor, e.g. bridges, amplifiers or signal conditioning of resistance-strain gauges
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01L—MEASURING FORCE, STRESS, TORQUE, WORK, MECHANICAL POWER, MECHANICAL EFFICIENCY, OR FLUID PRESSURE
    • G01L9/00—Measuring steady of quasi-steady pressure of fluid or fluent solid material by electric or magnetic pressure-sensitive elements; Transmitting or indicating the displacement of mechanical pressure-sensitive elements, used to measure the steady or quasi-steady pressure of a fluid or fluent solid material, by electric or magnetic means
    • G01L9/0041—Transmitting or indicating the displacement of flexible diaphragms
    • G01L9/0051—Transmitting or indicating the displacement of flexible diaphragms using variations in ohmic resistance
    • G01L9/006—Transmitting or indicating the displacement of flexible diaphragms using variations in ohmic resistance of metallic strain gauges fixed to an element other than the pressure transmitting diaphragm
    • G01L9/0064—Transmitting or indicating the displacement of flexible diaphragms using variations in ohmic resistance of metallic strain gauges fixed to an element other than the pressure transmitting diaphragm the element and the diaphragm being in intimate contact

Abstract

A differential pressure sensor has a star cantilever member 1 on which a pair of strain gauges 2 are mounted, one on each face. The star cantilever is secured between a pair of flexible sealing diaphragms 3 in a housing 4 which allows fluid pressure to be applied to each diaphragm. The strain gauges are connected in a Wheatstone bridge configuration (Fig. 3). The driving circuit operates in a pulsed mode to extend the lifetime of the strain gauges. <IMAGE>

Description

SPECIFICATION Differential Pressure Sensor This invention relates to differential pressure sensors.
A differential pressure sensor is a device designed to measure and give an output indicative of the difference, usually small, between two sources of pressure. In this respect it can be distinguished from a pressure gauge which measures absolute pressure in a fluid containing system.
According to the invention there is provided a differential pressure sensor comprising one or more strain gauges mounted on one or more flexible cantilever members extending inwardly from and in the plane of a flat annulus which is placed between and in contact with two flexible sealing diaphragms, the whole being secured in a housing having fluid pressure access means on each side of the pair of diaphragms.
In a preferred embodiment the sensor includes an electrical circuit to which the strain gauge(s) is (are) connected in a Wheatstone bridge configuration to the input(s) of a differential amplifier.
An embodiment of the invention will now be described with reference to the accompanying drawings, in which: Fig. 1 is an exploded view of a differential pressure sensor.
Fig. 2 is a view of the assembled sensor of Fig.
1,and Fig. 3 is a preferred form of circuit for use with the sensor of Fig. 1.
The differential pressure sensor shown in figs.
1 and 2 comprises a so-called "star cantilever" member 1 having a pair strain gauges 2 mounted on each side of one of the inwardly projecting cantilever members. The star cantilever member 1 is placed between two flexible sealing diaphragms 3 and the resulting 3-layer structure is secured between two cantilever housing members 4 which are secured together by a series of rivets 5. The housing members 4 are provided with connectors 6 which enable the complete sensor unit to be coupled to pipes 7 using conventional compression nut and ferrule means 8, 9.
When connected into a system fluid pressure is applied via the diaphragms 3 to both sides of the star cantilever. When there is a pressure differential between the two sides the cantilever limbs will bend, the amount of bend being dependent on the difference in the pressures, and the strain gauges will produce outputs proportional to the amount of bend.
The strain gauges are preferably connected in a circuit as shown in Fig. 3. The two gauges together with fixed resistors 10,11 are connected in a Wheatstone bridge configuration to the inputs of a differential amplifier 12. The bridge is supplied with a fixed direct voltage at terminal 13.
The strain gauges are supplied with a pulsed direct voltage from terminal 14 via a transistor 1 5. The transistor is controlled by a pulse generator built around amplifier 1 6. The ratio of on/off times is typically 0.12 ms to 40 ms. A pulsed operation of the strain gauges in this manner leads to an extended life to the gauges.
The output of amplifier 12 is fed to a peak detecting circuit. Provision is made for applying a d.c. offset control at point B in order that the circuit may be initially balanced under normal operating conditions.
Although the arrangement of Fig. 1 and the circuit of Fig. 3 are described with reference to two strain gauges it is possible to use only one strain gauge or several pairs of strain gauges in the sensor unit. The necessary modifications to the circuit will be readily effected by those skilled in the art. Similarly, the details of the pulse generator can be varied to suit the particular application.
Claims
1. A differential pressure sensor comprising one or more strain gauges mounted on one or more flexible cantilever members extending inwardly from and in the plane of a flat annulus which is placed between and in contact with two flexible sealing diaphragms, the whole being secured in a housing having fluid pressure access means on each side of the pair of diaphragms.
2. A sensor according to claim 1 having at least two strain gauges mounted on opposite faces of the same flexible cantilever member.
3. A sensor according to claim 1 or 2 including an electrical circuit to which the strain gauge(s) is (are) connected in a Wheatstone bridge configuration to the input(s) of a differential amplifier.
4. A sensor according to any preceding claim wherein the strain gauges are supplied with a pulsed direct voltage.
5. A differential pressure sensor substantially as described with reference to Figs. 1 and 2 or Figs. 1, 2 and 3 of the accompanying drawings.
**WARNING** end of DESC field may overlap start of CLMS **.

Claims (5)

**WARNING** start of CLMS field may overlap end of DESC **. SPECIFICATION Differential Pressure Sensor This invention relates to differential pressure sensors. A differential pressure sensor is a device designed to measure and give an output indicative of the difference, usually small, between two sources of pressure. In this respect it can be distinguished from a pressure gauge which measures absolute pressure in a fluid containing system. According to the invention there is provided a differential pressure sensor comprising one or more strain gauges mounted on one or more flexible cantilever members extending inwardly from and in the plane of a flat annulus which is placed between and in contact with two flexible sealing diaphragms, the whole being secured in a housing having fluid pressure access means on each side of the pair of diaphragms. In a preferred embodiment the sensor includes an electrical circuit to which the strain gauge(s) is (are) connected in a Wheatstone bridge configuration to the input(s) of a differential amplifier. An embodiment of the invention will now be described with reference to the accompanying drawings, in which: Fig. 1 is an exploded view of a differential pressure sensor. Fig. 2 is a view of the assembled sensor of Fig. 1,and Fig. 3 is a preferred form of circuit for use with the sensor of Fig. 1. The differential pressure sensor shown in figs. 1 and 2 comprises a so-called "star cantilever" member 1 having a pair strain gauges 2 mounted on each side of one of the inwardly projecting cantilever members. The star cantilever member 1 is placed between two flexible sealing diaphragms 3 and the resulting 3-layer structure is secured between two cantilever housing members 4 which are secured together by a series of rivets 5. The housing members 4 are provided with connectors 6 which enable the complete sensor unit to be coupled to pipes 7 using conventional compression nut and ferrule means 8, 9. When connected into a system fluid pressure is applied via the diaphragms 3 to both sides of the star cantilever. When there is a pressure differential between the two sides the cantilever limbs will bend, the amount of bend being dependent on the difference in the pressures, and the strain gauges will produce outputs proportional to the amount of bend. The strain gauges are preferably connected in a circuit as shown in Fig. 3. The two gauges together with fixed resistors 10,11 are connected in a Wheatstone bridge configuration to the inputs of a differential amplifier 12. The bridge is supplied with a fixed direct voltage at terminal 13. The strain gauges are supplied with a pulsed direct voltage from terminal 14 via a transistor 1 5. The transistor is controlled by a pulse generator built around amplifier 1 6. The ratio of on/off times is typically 0.12 ms to 40 ms. A pulsed operation of the strain gauges in this manner leads to an extended life to the gauges. The output of amplifier 12 is fed to a peak detecting circuit. Provision is made for applying a d.c. offset control at point B in order that the circuit may be initially balanced under normal operating conditions. Although the arrangement of Fig. 1 and the circuit of Fig. 3 are described with reference to two strain gauges it is possible to use only one strain gauge or several pairs of strain gauges in the sensor unit. The necessary modifications to the circuit will be readily effected by those skilled in the art. Similarly, the details of the pulse generator can be varied to suit the particular application. Claims
1. A differential pressure sensor comprising one or more strain gauges mounted on one or more flexible cantilever members extending inwardly from and in the plane of a flat annulus which is placed between and in contact with two flexible sealing diaphragms, the whole being secured in a housing having fluid pressure access means on each side of the pair of diaphragms.
2. A sensor according to claim 1 having at least two strain gauges mounted on opposite faces of the same flexible cantilever member.
3. A sensor according to claim 1 or 2 including an electrical circuit to which the strain gauge(s) is (are) connected in a Wheatstone bridge configuration to the input(s) of a differential amplifier.
4. A sensor according to any preceding claim wherein the strain gauges are supplied with a pulsed direct voltage.
5. A differential pressure sensor substantially as described with reference to Figs. 1 and 2 or Figs. 1, 2 and 3 of the accompanying drawings.
GB7908180A 1979-03-08 1979-03-08 Differential pressure sensor Expired GB2043907B (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
GB7908180A GB2043907B (en) 1979-03-08 1979-03-08 Differential pressure sensor

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
GB7908180A GB2043907B (en) 1979-03-08 1979-03-08 Differential pressure sensor

Publications (2)

Publication Number Publication Date
GB2043907A true GB2043907A (en) 1980-10-08
GB2043907B GB2043907B (en) 1983-04-20

Family

ID=10503719

Family Applications (1)

Application Number Title Priority Date Filing Date
GB7908180A Expired GB2043907B (en) 1979-03-08 1979-03-08 Differential pressure sensor

Country Status (1)

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GB (1) GB2043907B (en)

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP1180672A1 (en) * 2000-07-25 2002-02-20 AB Elektronik GmbH Pressure sensor
GB2534222A (en) * 2015-01-19 2016-07-20 Frequency Prec Ltd Pressure sensor and device comprising the same
US10697844B2 (en) * 2017-04-19 2020-06-30 Huba Control Ag Compact pressure transducer

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP1180672A1 (en) * 2000-07-25 2002-02-20 AB Elektronik GmbH Pressure sensor
GB2534222A (en) * 2015-01-19 2016-07-20 Frequency Prec Ltd Pressure sensor and device comprising the same
GB2534222B (en) * 2015-01-19 2017-11-15 Frequency Prec Ltd Pressure sensor and device comprising the same
US10591375B2 (en) 2015-01-19 2020-03-17 Frequency Precision Ltd. Pressure sensor and device comprising the same
US10697844B2 (en) * 2017-04-19 2020-06-30 Huba Control Ag Compact pressure transducer

Also Published As

Publication number Publication date
GB2043907B (en) 1983-04-20

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Legal Events

Date Code Title Description
746 Register noted 'licences of right' (sect. 46/1977)
PCNP Patent ceased through non-payment of renewal fee