TWI454678B - Pressure sensing device and its pressure sensing circuit - Google Patents

Description

Pressure sensing device and pressure sensing circuit thereof

The present invention relates to sensing devices and, more particularly, to a pressure sensing device and its pressure sensing circuit.

In general, the pressure sensing device such as a tire pressure, air pressure, and water pressure is usually measured by a pressure sensing device such as a U-tube pressure gauge or a Bourdon-tube gage.

The above-mentioned U-tube pressure gauge usually uses water or mercury as the standard liquid in the tube; when the U-shaped tube is open at both ends without pressure, the liquid levels of the two tubes are on the same level. If there is a pressure difference at both ends, the height of the liquid column will have a difference. The height difference of the liquid column can properly represent the pressure difference between the two ends of the U-tube, so as to measure the pressure of the pressure source.

The above-mentioned Bouton pressure gauge bends a copper alloy thin tube having an elliptical cross section into a circular arc shape, and the copper alloy thin tube is sealed at one end and allows an active stretching space, and the other end is not closed and welded. On a pipe joint. When the gas or liquid pressure is introduced from the pipe joint, the bent pipe has a tendency to expand outward, and the end of the copper alloy thin pipe is pulled through a link, so that the sector gear with the pointer is oscillated. When the difference between the outer circumference and the inner circumference of the copper alloy thin tube is equal to the elastic force of the elbow itself, the pointer is fixed at a certain position on the dial, and the scale pointing to it indicates the gas pressure.

However, the U-tube pressure gauge not only has a low precision of measurement, but most of the tubes used are made of glass materials, and are easily suspected of being broken and inconvenient to store; in addition, the inside of the U-tube pressure gauge Liquids often change volume due to temperature changes and lead to errors in measurement. The volume of the bend of the Bouton-type pressure gauge will also change with the temperature of the environment or the pressure source, and the bent pipe will be prone to metal fatigue after a certain number of stretches, which is easy to cause pressure measurement. The accuracy is reduced.

Therefore, the industry has developed a piezoelectric pressure sensing device to improve the shortcomings of the U-tube pressure gauge and the Bouton pressure gauge described above. The piezoelectric pressure sensing device is made of a piezoelectric material. When the piezoelectric material is squeezed by the pressure of the pressure source, the electric dipole moment in the piezoelectric material is shortened due to compression. In order to resist this change, the piezoelectric material generates positive and negative charges on the surface of the piezoelectric material to maintain the original state, thereby accurately calculating the pressure value of the pressure source by measuring the amount of positive and negative charges generated on the surface of the piezoelectric material.

However, the piezoelectric pressure sensing device described above can improve the low accuracy of the conventional pressure sensing device and the disadvantage of being susceptible to temperature, but the piezoelectric pressure sensing device directly applies pressure to the pressure source through the pressure source. The electrical pressure sensing device is prone to rust, moisture or damage after a period of use. In addition, in order to avoid the danger of electrical ignition, the piezoelectric pressure sensing device is not suitable for the pressure measurement of the flammable gas, so that the measurable field of the piezoelectric pressure sensing device is thus subject to limit. Therefore, based on the above, it can be known that the conventional pressure sensing device is still not perfect, and there is still room for improvement.

In view of this, the main object of the present invention is to provide a pressure sensing device and a pressure sensing circuit thereof, which not only have better accuracy in sensing, but also can be applied to various measurement fields.

In order to achieve the above object, the pressure sensing device provided by the present invention comprises a housing, a coil, a magnetic member and a pressure sensing circuit; wherein the housing has a detecting hole, and one end of the detecting hole is used In contact with the pressure source; the coil is made of a conductive material and is disposed on the housing; the magnetic member is disposed in the housing in a movable manner relative to the coil; the pressure sensing circuit is The coil is electrically connected.

Thereby, when the magnetic member is moved by the pressure of the pressure source through the detecting hole, the coil is affected by the magnetic force when the magnetic member moves to generate a corresponding induced electromotive force, and the pressure sensing circuit receives the After the induced electromotive force is induced, the displacement amount of the magnetic member is calculated through the value of the induced electromotive force, and is converted into a pair of voltage signals corresponding to the displacement amount according to the displacement amount, and then output.

In addition, according to the above concept, the pressure sensing circuit mainly includes a displacement sensing circuit and a conversion circuit, wherein the displacement sensing circuit is electrically connected to the coil for pushing the magnetic member by the pressure of the pressure source. And causing the coil to generate the induced electromotive force, receiving the induced electromotive force, and calculating the displacement amount of the magnetic component through the value of the induced electromotive force, and outputting; the conversion circuit is electrically connected to the displacement sensing circuit to The displacement amount calculated by the displacement sensing circuit is converted into the voltage signal output corresponding to the displacement amount.

In order that the present invention may be more clearly described, the preferred embodiments are illustrated in the accompanying drawings.

Referring to FIG. 1 , a pressure sensing device 1 according to a preferred embodiment of the present invention measures the pressure of a pressure source according to the pressure. In this embodiment, the gas pressure in a gas tube 100 is measured, but not Limited. The pressure sensing device 1 includes a housing 10, a coil 20, a stretch film layer 25, a magnetic member 30, a spring 35, and a pressure sensing circuit 40. Wherein: the housing 10 includes a base 11, a cover 12 and a casing 13. The base 11 has a detecting hole 111, and one end of the detecting hole 111 is used to communicate with the gas pipe 100, so that gas in the gas pipe 100 can be guided into the casing 10 through the detecting hole 111. The cover 12 is disposed on the base, and the cover 12 has a main body 121 and an adjustment knob 122. The main body 121 has an accommodating space 121a therein, and the main body 121 has a receiving space and a receiving space. 121a communicates with the screw hole 121b; the adjustment knob 122 is disposed in the screw hole 121b. The outer casing 13 is overlaid on the cover 12 and shields the cover 12.

The coil 20 is made of a conductive material such as copper, iron, silver or the like. The coil 20 is disposed on the main body 121 of the cover 12 so as to surround the periphery of the accommodating space 121a.

The stretch film layer 25 is made of a material having a stretchable effect. The stretch film layer 25 is sleeved on the base 11 to seal the other end of the detecting hole 111. And it can be pushed by the gas pressure to extend in the direction of the accommodating space 121a.

The magnetic member 30 is configured to generate a magnetic force and is disposed in the accommodating space 121a so as to be movable relative to the coil 20, and is connected to the layer of the stretch film 25. In addition, in the present embodiment, the magnetic member 30 is exemplified by a permanent magnet, but not limited thereto, and an electromagnet, a magnet, or other magnetic member having a magnetic force may be used instead.

The spring 35 is disposed in the accommodating space 121a. One end of the spring 35 is coupled to the adjusting knob 122 and the other end is coupled to the magnetic member 30 to adjust the position of the magnetic member 30 by rotating the adjusting knob 122 to push the spring 35.

By using the detecting hole 111, the gas pressure is pushed to push the stretch film layer 25 to extend in the direction of the accommodating space 121a, so as to drive the magnetic member 30 to move relative to the coil 20 (as shown in FIG. 2), and The magnitude of the movement of the magnetic member 30 is proportional to the instantaneous pressure change of the pressure source, and then the magnetic force changes when the magnetic member 30 moves, so that the coil 20 generates a corresponding induced electromotive force, and the inductance generated by the coil 20 The electromotive force is proportional to the magnitude of the movement of the magnetic member 30 in step A.

The pressure sensing circuit 40 is disposed in the housing 10 and located between the cover 12 and the outer casing 13 and electrically connected to the coil 20 . Referring to FIG. 3 , the pressure sensing circuit 40 includes a displacement sensing circuit 41 , a conversion circuit 42 electrically connected to the displacement sensing circuit 41 , an adjustment circuit 43 electrically connected to the conversion circuit 42 , and An output port 44 electrically connected to the adjustment circuit 43. The displacement sensing 41 circuit is electrically connected to the coil 20 for receiving the induced electromotive force and transmitting the value of the induced electromotive force when the magnetic component 30 is driven by the gas pressure to cause the coil 20 to generate the induced electromotive force. The displacement amount of the magnetic member 30 is estimated. In the present embodiment, the displacement sensing circuit 41 is mainly composed of a magnetic coupling circuit 411 and an electromagnetic induction circuit 412, so as to calculate the displacement represented by the induced electromotive force by magnetic coupling and electromagnetic induction with the coil 20. , but not limited to this.

The conversion circuit 42 is configured to convert the displacement amount calculated by the displacement sensing circuit 41 into the voltage signal corresponding to the displacement amount, and in addition, the voltage signal can be more accurate for the conversion circuit 42 to convert and output, and the conversion circuit can be more accurate. 42 is provided with a filter circuit 421 for filtering out unnecessary bands which may cause interference or floating signals, so that the voltage signal converted by the conversion circuit 42 can be more accurate.

The adjusting circuit 43 is configured to adjust the voltage signal output by the converting circuit 42. In this embodiment, the adjustment circuit 43 is mainly composed of a multiplication circuit 431 and a subtraction circuit 432 for performing zero reset, fine adjustment, amplification, etc. on the voltage signals output by the conversion circuit 42, but the circuit design is Not limited to this.

The output port 44 is used to output the adjusted voltage signal of the adjustment circuit 43.

Thereby, the user can estimate the pressure of the pressure source by analyzing the voltage signal outputted by the output port 44. For example, when the pressure of the pressure source increases, the voltage signal output by the output port 44 will depend on The predetermined ratio is increased, and when the pressure of the pressure source is weakened, the voltage signal outputted by the output port 44 is decreased by a predetermined ratio, so that the user can push the pressure source through the voltage signal outputted by the output port 44. The pressure value.

In addition, the magnitude of the movement of the magnetic member 30 can be accurately sensed by the manner in which the induced electromotive force is generated by the magnetic force change, so that the pressure sensing device 1 of the present invention can accurately calculate the pressure value to be measured.

Furthermore, the present invention seals the design of the detecting hole 111 through the stretch film layer 25, so that the coil 20 having electrical flow characteristics and the pressure sensing circuit 40 are separated from the pressure source to be measured. The effect of gas-electric separation or liquid-electric separation makes the pressure sensing device 1 suitable for pressure measurement of ordinary gas and liquid, and can also be applied to pressure measurement of gas and liquid with flammable characteristics. It can be used for different measurement environments.

The above description is only for the preferred embodiments of the present invention, and the equivalent structures and manufacturing methods of the present invention and the scope of the patent application are intended to be included in the scope of the present invention.

1. . . Pressure sensing device

10. . . case

11. . . Pedestal

111. . . Probe hole

12. . . Cover

121. . . main body

121a. . . Housing space

121b. . . Screw hole

122. . . Adjustment knob

13. . . shell

20. . . Coil

25. . . Stretch film layer

30. . . Magnetic parts

35. . . spring

40. . . Pressure sensing circuit

41. . . Displacement sensing circuit

411. . . Magnetic coupling circuit

412. . . Electromagnetic induction circuit

42. . . Conversion circuit

421. . . Filter circuit

43. . . Adjustment circuit

431. . . Multiplication circuit

432. . . Subtraction circuit

44. . . Output埠

100. . . Gas tube

BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a block diagram of a preferred embodiment of the present invention.

2 is an actuation diagram of a preferred embodiment of the present invention for sensing pressure.

3 is a block diagram showing the structure of a pressure sensing circuit of the present invention.

20. . . Coil

40. . . Pressure sensing circuit

41. . . Displacement sensing circuit

411. . . Magnetic coupling circuit

412. . . Electromagnetic induction circuit

42. . . Conversion circuit

421. . . Filter circuit

43. . . Adjustment circuit

431. . . Multiplication circuit

432. . . Subtraction circuit

44. . . Output埠

Claims (11)

a pressure sensing device for sensing the pressure of a pressure source; the pressure sensing device comprises: a housing having a detecting hole, one end of the detecting hole is in contact with the pressure source; a coil, The device is made of a conductive material and is disposed on the casing; a magnetic member is disposed in the casing so as to be movable relative to the coil; and a pressure sensing circuit is electrically connected to the coil; thereby, When the magnetic member is moved by the pressure of the pressure source through the detecting hole, the coil is affected by the magnetic force when the magnetic member moves to generate a corresponding induced electromotive force, and the pressure sensing circuit receives the induced electromotive force. The displacement amount of the magnetic member is calculated by the value of the induced electromotive force, and is converted into a pair of voltage signals corresponding to the displacement amount according to the displacement amount, and then output. The pressure sensing device of claim 1, further comprising a stretch film layer disposed in the housing, sealing the other end of the detecting hole, and located between the detecting hole and the magnetic member, and the magnetic The expansion film layer is configured to be pushed by the pressure of the pressure source to stretch and move the magnetic member. The pressure sensing device of claim 1, comprising a spring having one end abutting the housing and the other end abutting the magnetic member; the magnetic member being pushed by the pressure of the pressure source The direction of the spring moves. The pressure sensing device of claim 3, wherein the housing comprises a base and a cover; the base is provided with the detecting hole; the cover is attached to the base, and the cover is The inside of the cover has an accommodating space; the magnetic member and the spring are disposed in the accommodating space. The pressure sensing device of claim 4, wherein the cover comprises a main body and an adjustment knob, the main body has the accommodating space and a screw hole communicating with the accommodating space; In the screw hole, and the end of the spring is abutted, and the spring is adjusted by rotating the adjustment knob to adjust the position of the magnetic member. The pressure sensing device of claim 1, wherein the pressure sensing circuit comprises a displacement sensing circuit and a conversion circuit, wherein the displacement sensing circuit is electrically connected to the coil for receiving the magnetic component When the pressure of the pressure source is pushed to cause the coil to generate the induced electromotive force, the induced electromotive force is received, and the displacement of the magnetic member is estimated by the value of the induced electromotive force, and then outputted; the conversion circuit is electrically connected to the displacement sensing circuit. The displacement amount calculated by the displacement sensing circuit is converted into the voltage signal output corresponding to the displacement amount. The pressure sensing device of claim 6, wherein the pressure sensing circuit further comprises an adjustment circuit electrically connected to the conversion circuit for adjusting a voltage signal output by the conversion circuit. The pressure sensing device of claim 7, wherein the pressure sensing circuit further comprises an output port electrically connected to the adjusting circuit for outputting the adjusted voltage signal of the adjusting circuit. A pressure sensing circuit is electrically connected to a coil, and the coil is located in a magnetic range of a magnetic component; the pressure sensing circuit comprises: a displacement sensing circuit electrically connected to the coil, Receiving the induced electromotive force when the magnetic element is driven by a pressure source to cause the coil to generate an induced electromotive force, and calculating a displacement amount of the magnetic member through the value of the induced electromotive force; and a conversion circuit, The displacement sensing circuit is electrically connected to output a pair of voltage signal outputs corresponding to the displacement amount according to the displacement amount calculated by the displacement sensing circuit. The pressure sensing circuit of claim 9, further comprising an adjustment circuit electrically connected to the conversion circuit for adjusting a voltage signal output by the conversion circuit. The pressure sensing circuit of claim 10 further includes an output port electrically coupled to the adjustment circuit for outputting the adjusted voltage signal of the adjustment circuit.