WO1998052007A1 - A magnetic induction type pressure sensor - Google Patents

Abstract

The invention disclosed is a magnetic induction type pressure sensor comprising bourdon pipe, transmission mechanism and printed circuit board. The bourdon pipe could product a linear deformation proportionally pressure acting on it, to drive central rotation shaft through the transmission mechanism. There is a rotating dish on the shaft, with magnet provided for the outer edge. When the rotating dish relatively move to the printed circuit board the magnetic spring switch whereon could be inducted to close through magnetism of the magnetic in order to turn on the circuit by the magnetic spring switch. Displacement produced by the bourdon pipe, corresponding being measured pressure, could drive the rotating dish to pivot the central rotation shaft through the transmission mechanism, as to turn on the magnetic spring switch on the corresponding position to obtain the corresponding resistance value.

Description

MAGNETIC-INDUCTION PRESSURE SENSOR FIELD OF THE INVENTION

The present invention relates to a magnetically induced pressure sensor, in particular to a pressure sensor that utilizes the deformation of the Baden tube to drive the transmission mechanism to cause the turntable to rotate. When the magnet on the front edge of the turntable rotates and moves on the reed switch of the printed circuit When different magnetic reed switches are magnetized, the series circuits of different magnetic reed switches and different resistors are turned on to transmit signals to achieve a magnetic induction pressure sensor for accurate pressure measurement.

narrative of prior art

Pressure is one of the most commonly used measurement variables in industrial control programs. Its importance can be known from the fact that pressure gauges are installed in industrial equipment or instruments to measure pressure, such as oil pressure and air pressure in vehicles. .

Please refer to FIG. 1, which is a structural diagram of a known pressure sensor. A small airtight chamber is formed in the body 11, which is a pressure chamber 13. The pressure is passed into this pressure chamber 13, then The copper diaphragm 14 in the body 11 will expand outward due to pressure; the n-shaped bracket 15 in the cover body 12 is the main structure, which can turn a small angle in one direction, from the door-shaped bracket 15 A contact piece 17 is extended above the top of the contact piece 17, and the top of the contact piece 17 is in contact with the wire-wound resistor 18 on the bakelite piece 19, and the bakelite piece 19 is fixed on the body 11; when When the copper diaphragm 14 in the main body 11 expands outward, it must hold the raised part 16 under the door-shaped bracket 15, so that the contact piece 17 linked with the door-shaped bracket 15 will be displaced accordingly , sliding on the wire-wound resistor 18, the magnitude of the pressure can be known as the resistance changes.

The conventional pressure sensor has the following disadvantages due to the above-mentioned structural relationship:

1. The pressure sensor in the form of a copper diaphragm is used. When measuring different pressures, it is necessary to select copper diaphragms of different thicknesses to match the measurement, so as to meet the requirements of measurement accuracy. In terms of technology and manufacturing costs, both form a problem. Many questions.

2. The pressure sensor in the form of a copper diaphragm is used. Because only one copper sheet is stamped into a concave-convex shape, the deformation caused by the change of pressure is not large, so the winding area of the wire-wound resistor cannot be too long, and the winding distance is also small. must be small, resulting in low resolution and relatively large error.

3. The conventional contact piece in the pressure sensor in the form of a copper diaphragm is in contact with the winding resistance, and the read pressure value will be affected by factors such as the contact area and contact angle; or due to poor control of the winding density , it is easy to cause measurement errors and affect the accuracy.

4. The conventional pressure sensor in the form of a copper diaphragm needs to install the copper diaphragm in the pressure chamber in advance. Since it is not easy to replace the copper diaphragm, it cannot be replaced immediately according to the pressure, which is not ideal. .

The conventional pressure sensor structure, from the above statements, proves that there are still many shortcomings. In view of this, the The object of the invention is to provide a magnetic induction pressure sensor with simple and firm structure, easy assembly and high precision.

In order to avoid measurement errors caused by direct contact of the pointer with the resistance, the magnetic induction pressure sensor of the present invention uses a printed circuit board (PCB) with a reed switch (Reed Switch), and the reed switch is magnetically induced to conduct the circuit , to transmit the resistance signal to the meter to read the pressure.

The magnetic reed switch is composed of a magnetic material, equipped with more than two elastic and identical tongues (magnetic reeds), and uses an external magnetic field to make the two tongues close or open, in order to break or continue the current. The characteristic switching element; the shape of the magnetic reed and the structure of the contact part often have different designs.

In terms of reliability and response speed, the magnetic reed switch is more open than the usual mechanical switch and close to the semiconductor switch; the magnetic reed switch is often used in the situation where small size, high reliability and current value are required to be below 1 - 0.5 A use.

Compared with general mechanical switches, the reed switch has many advantages such as small shape, suitable for mass production, long service life, vibration resistance, and fast response speed; therefore, it is adopted by the present invention and applied to the magnetic induction of the present invention on the pressure sensor.

The magnetic induction pressure sensor of the present invention is composed of a Baden tube at the lower end of the sensor, a transmission mechanism in the middle, and a printed circuit board connected to the upper end of the transmission mechanism; the Baden tube is subjected to pressure and produces uniform deformation. Withstand the convex transmission plate in the transmission mechanism, and through the interlocking of the various components in the transmission mechanism, the central shaft will be driven to rotate, so that the turntable on the central shaft will move on the printed circuit board. Different pressures will produce different effects on the turntable. Displacement; By means of the magnet on the front edge of the turntable, the reed switch set on the printed circuit board is induced, and the reed switch at different positions is turned on, so that different resistance values are read, and the displacement caused by different pressures can be measured. The pressure signal can be accurately transmitted to the instrument to achieve the purpose of reading the pressure. Since the pressure signal of the present invention is transmitted by the magnetic induction conduction circuit, there is no error in contact measurement, and the pressure can be measured more accurately.

Another feature of the present invention is that the TP point can be set on the printed circuit, and the position of the warning switch can be selected by the TP point; if any pressure scale on the instrument is set as the warning point of the pressure warning function, it can be used at On the printed circuit, the T P point corresponding to the pressure scale takes out the signal; when the magnet moves to the set magnetic reed switch, the T P point on the circuit forms a conduction, and if an alarm is added in between, the warning can be achieved function; or the warning signal of T P point can be sent to other control circuits.

In addition, the magnetic induction pressure sensor of the present invention can be filled with suitable insulating oil or silicone oil inside the sensor. In addition to providing anti-corrosion for internal components, it also has the function of absorbing vibration; When it is inside, the internal oil has the effect of buffering and absorbing vibration, so it can maintain the function of measurement accuracy.

In order to further understand the characteristics and technical contents of the present invention, please refer to the following drawings and detailed descriptions of the present invention, but the attached drawings are only for reference and illustration, and are not intended to limit the present invention. Illustration

Figure 1 is a known structure.

Fig. 2 is an exploded view of the structure of the present invention.

Fig. 3 is a schematic diagram of a printed circuit board in the present invention.

Fig. 4 is a circuit diagram of the printed circuit board of the present invention.

Fig. 5 is an exploded view of the transmission structure of the present invention.

Figure 6 is a schematic diagram of the use of the present invention.

Fig. 7 is a related schematic diagram of setting warning points and matching terminals in the present invention.

Fig. 8 is an exploded schematic view of components of another embodiment of the present invention.

Fig. 9 is a schematic diagram related to another implementation of setting warning points in the present invention.

The meaning of each label in the diagram

1 1. -Body 12. .Cover

1 3. .pressure chamber 14. .copper diaphragm

15. ^-shaped bracket 16. .Protruding part

17. . shaped contact pieces 18. . wire wound resistors

19. Bakelite chips

21. Baden tube 22. Protrusion

23. . Screw hole 24. . Pressure supply hole

25. .male thread 26. .pressure pipe

30. Trapezoidal top piece 31. Fixing screw

32. .round hole 33. .round hole

34. .Bottom 35. .Support

36. . Curved transmission piece 37. . Transmission rod

38. . Convex drive piece 39. . Pin

40. hairspring 41. central shaft gear

42. Central shaft

50. .printed circuit board 52. .resistor

54. .Reed switch 56. .Round hole

57. .signal wire a 58. .signal wire b

59. Signal wire c

60. 'Turntable 65. .Magnet 70.. Insulation gasket 72.. Terminal

74..Terminals

80..Meter

90.. Bottom cover 92.. O-ring

94.. Cylinder body 96.. Pressure pipe body

100. Seat body 102. Central round hole

104. Round hole 106. Positioning guide post

110. Annular sheet 112. Resistor

114. Reed switch 116. Card slot

120. Pointer 125. Magnet Example

Please refer to FIG. 2, which is an exploded view of the structure of the magnetic induction pressure sensor of the present invention; it can be seen from the accompanying drawings that the present invention includes a terminal 72, a cylinder 94, and a turntable from top to bottom. 6 0. Printed circuit board

50. The transmission mechanism, part of the Baden tube 21, the O-ring 92 and the lower cover 90; please also refer to FIG. 3 and FIG. 4, which are on the printed circuit board 50 of the present invention , the relevant positions and circuit diagrams of the resistor 5 2 and the reed switch 5 4; it can be seen from the drawings that nine resistors 5 2 (R 1 R 9 ) and nine reed switches 5 4 ( R d 1 R d 9 ); the action principle is that when the turntable 60 moves on the printed circuit board 50 due to the different displacements of the lower transmission mechanism due to the different pressure, the magnet on the front edge of the turntable 60 6 5 respectively pass through each magnetic reed switch 5 4 on the printed circuit board 5 0; the magnetic reed switch 5 4 is affected by the magnet

6 5 induction, the two separate magnetic reeds inside the reed switch 5 4 are closed to conduct the series circuit formed by different reed switches 5 4 and different resistors 5 2; if the magnet 6 5 moves to the reed switch 5 4 ( R d 1 ), the reed switch 5 4 ( R d 1 ) inner magnetic reed closes the conduction circuit, and there is only one resistance in the conduction series circuit

5 2 ( R 1 ), the resistance value of the circuit between a and b is R 1 , and the resistance value is small; when the magnet 6 5 moves to the reed switch

When 5 4 ( R d 2 ), the magnetic reed switch 5 4 ( R d 2 ) inner magnetic reed closes the conduction circuit, and there are two resistors 5 2 ( R 1 , R 2 ) in the conduction series circuit, the circuit between a and b The resistance value of R 1 + R 2 ; similarly, when the magnet

When 6 5 moves to the magnetic reed switch 5 4 ( R d 9 ), the inner magnetic reed of the magnetic reed switch 5 4 ( R d 9 ) closes the conducting circuit, and on the conducting series circuit, there are nine resistors 5 2 ( R l +.... + R 9 ), the resistance value of the circuit between ab is R 1 + R 2 +.... + R 8 + R 9, the resistance value increases; therefore, the magnet 6 5 moves to different positions, Different resistance values can be read, and then the signal is transmitted to the meter 80 through the signal wire a57 and the signal wire b58 (as shown in Figure 6) to read the value of the pressure. Another feature of the present invention is that the position of the warning switch can be selected by using the TP point; if the eighth grid pressure scale representing 80 is set as the warning point of the pressure warning function, the corresponding TP on the printed circuit can be Take out the signal at 8 points; when the magnet moves to the magnetic reed switch 5 4 (R d 8 ), the point a and TP 8 points on the circuit will form a conduction, if an alarm is added in between, the warning function can be achieved ; Or the warning signal of TP 8 can be sent to other control circuits. Of course, TP 1 - TP 9 can also be selected according to different requirements.

Please refer to FIG. 5, which is a schematic diagram of the internal transmission mechanism and the Baden tube 21 of the magnetic induction pressure sensor of the present invention; Baden tube 2 1 , protrusion 2 2 , screw hole 2 3 provided on the upper surface of protrusion 2 2 , pressure delivery hole 2 4 , male thread 1 5 and pressure delivery pipe 2 6 ; 5 Connected pressure delivery pipe body 9 6 input, via pressure delivery hole 2 4 to Baden tube

The pressure delivery pipe 26 in the body of 21 causes the Baden tube 21 to be compressed and produces uniform deformation; due to the deformation of the Baden tube 21, it drives the convex transmission piece 38; The other end of the transmission rod piece 37 joined by the transmission piece 38 is also engaged with the curved transmission tooth piece 36 by the pin 39, and the tooth shape of the curved transmission tooth piece 36 meshes with the central shaft gear 41; Therefore, when the deformation of the Baden tube 21 drives the convex transmission piece 38, it also causes the central shaft 42 to rotate; the hairspring 40 at the lower end of the central shaft gear 41 provides , for positioning; or when the pressure disappears after the transmission, provide the force for the central shaft 4 2 to return to the initial position; the central shaft 4 2 passes through the round hole in the center of the trapezoidal top piece 3 0, the rear end of the trapezoidal top piece 3 0 By means of the fixing element, pass through the round hole 33 on the ladder opening top sheet 30, and combine with the two supporting parts 35, the lower ends of the two supporting parts 35 are fixed on the bottom plate 34; two fixing screws 31 (as shown 7), is the round hole 56 passing through the printed circuit board 50, the trapezoidal top sheet

The two circular holes 32 provided at the front end of the 30 fix the printed circuit board 50 and the transmission mechanism to the screw holes 23 on the upper surface of the protruding body 22.

As shown in FIG. 6, the above-mentioned Baden tube 21 drives the transmission mechanism to make the turntable 60 move on the printed circuit board 50, and the magnetism of the magnet 65 on the turntable 60 induces the printed circuit board 5 The magnetic reed switch 54 on the printed circuit board 50 is used to conduct the series circuit formed by the magnetic reed switch 54 and the resistor 52 on the printed circuit board 50, and the signal wire a57, the signal wire b58 and the terminal 7 2 to send a signal to read the pressure on the meter 80.

Please also refer to FIG. 7, when on the printed circuit board 50, a warning point TP2 is set at the appropriate position (R1-R2) of the resistor 52, and a signal wire _c5 is set at TP2 9. Then connect the signal wire a57, the signal wire b58, and the signal wire c59 to the 3-pin connection terminal 74 to provide the output of the warning signal.

In addition, the structure of the present invention can also be made as shown in FIG. 8; as can be seen from FIG. 8, the above-mentioned disc-shaped printed circuit board 50 is replaced by an annular sheet 110 and used in conjunction with the seat body 100. ; A circuit is printed on the annular sheet 1 1 0, and the circuit has resistors 1 1 2 and reed switches 1 1 4; The card slot 116 on the seat body 100 snaps into the positioning guide post 106, and with the aid of the fixing element, the annular sheet 110 is installed in the seat body 100; and the seat body The central round hole 102 of the body 100 accommodates the passage of the central rotating shaft 42, and another round hole 102 is provided for passing through the fixing screw 31 and positioning the base body 100 on the transmission mechanism. The central rotating shaft 42 passing through the seat body 100 is combined with the pointer 120, and a magnet 125 is arranged at the front end of the pointer 120.

The Baden tube 21 senses the pressure and produces a uniform deformation, so that the transmission mechanism acts to promote the rotation of the central shaft 42; and the pointer 120 engaged with the central shaft 42 also follows the deformation of the Baden tube 21 and moves , the magnets 125 at the front end of the pointer 120 conduct the printed circuit in the annular sheet 110 at different positions respectively, and different rotational displacements will cause the magnetic reed switch 114 in the circuit to be affected by the magnet 1 25 senses and conducts the circuit, different positions have different resistance output, and then the value of pressure can be judged.

Since the magnetic reed switch 54 is applied on the printed circuit board 50, the way of reading the resistance value is not to directly contact the conductive circuit, but to use the magnetic reed switch 54 to conduct the circuit, which can avoid direct contact. Faults and errors in output signals make the pressure data read by the meter 80 more accurate;

The magnetic reed switch 54 has the characteristic of small size, and the magnetic reed switch 54 used in the present invention has a length of about 1.2 cm. The magnetic reed switch 54 is made of a glass tube covering two tongues (magnetic reeds), and the terminal pins extending from the two magnetic reeds are connected to the contacts of the printed circuit board 50 circuit.

In addition, installing the printed circuit board 50 inside the sensor has the advantages of simple structure, easy assembly, and time saving, and is suitable for mass production. Compared with the assembly of traditional pressure sensors, the present invention saves three times the adjustment and Assembly time.

In the circuit design of the present invention, the setting form of the warning point T P can be applied in many ways. In addition to the above-mentioned circuit, a magnetic reed switch can also be used in conjunction with it (as shown in Figure 9); when the pressure drops, The deformation of the Baden tube is reduced, which makes the magnet return to the initial position. When it moves to the resistance R 2 - R 3, when the magnetic reed switch is set to warn (TP) of low voltage, the magnetic reed switch is magnetically conducted at this time , to transmit the message of low voltage, so that the user can know the warning message. Certainly, the magnetic reed switch for warning function can be set according to the needs of users, either for low voltage warning, or for high voltage warning.

In addition, pour suitable insulating oil or silicone oil into the inside of the sensor, so that the components inside the sensor can be protected against corrosion; it can also absorb external vibrations, so that the internal components will not be affected by vibrations. When external vibrations are generated, they will be transmitted When it reaches the inside of the sensor, the oil inside has the effect of buffering and absorbing vibration, so that it can avoid the situation that affects the measurement accuracy.

To sum up, the present invention improves the shortcomings of the conventional pressure sensors with an ingenious structural design, and achieves the goals of simple structure, small error and high precision. Not only is it truly innovative in terms of spatial form, but it also fully complies with the new requirements of the patent law. The statutory requirements of novelty and progressiveness are filed in accordance with the law, and I urge your office to approve this patent case and create it with calendar. The specific embodiments above are used to describe the purpose, features and effects of the present invention in detail. For those familiar with this type of technology, according to the above description, some changes and modifications may be made to the specific embodiments without departing from Therefore, the patent scope of the present invention is only described by the appendix application patent scope.

Claims

Rights request 1. A magnetic induction pressure sensor, characterized in that its structure includes the following components: a terminal part, which is composed of an insulating gasket and a terminal, for providing signal output; a cylinder, which is a The cover of the cylinder has a round hole at the upper end of the center for the purpose of accommodating the wiring terminals; a turntable, which is a disc body, or can be of other shapes, and a magnet is set on the front edge to provide reed switch induction. It is used for the magnetic field; a round hole is set in the center for the central shaft to pass through to drive it; A printed circuit board, on which a resistor and a reed switch are installed. When the magnet on the turntable passes by and induces the reed switch, the two magnetic reeds in the reed switch are closed, and a series circuit including the resistor is turned on. , to read different resistance signals, the amount of pressure displacement of the Baden tube can be known, and then the value of pressure can be read; A transmission mechanism, which includes a curved transmission tooth piece, a transmission rod, a convex transmission piece, a hairspring, a central shaft gear, a central shaft, and a pin, is combined by a trapezoidal top piece, a fixing screw, a support piece, and a bottom plate to form a transmission mechanism ; a Baden tube, deformed to receive pressure, to drive the transmission mechanism; an O-ring, and The bottom cover is a bottom cover with a square hole in the center; With the above-mentioned components stacked in layers, with such a structure, the Baden tube is pressed to produce uniform deformation, which drives the transmission mechanism together to make the turntable move on the printed circuit board, and the magnet on the turntable induces the printed circuit board Different magnetic reed switches on the printed circuit board are used to conduct the series circuit formed by the magnetic reed switch and the resistor on the printed circuit board, and the wiring terminals are used to transmit signals to read the pressure on the instrument. 2. A magnetic induction pressure sensor according to claim 1, wherein the turntable structure is made of an insulating material, a magnet is placed on the front edge, and its shape can be disc-shaped, rod-shaped or Other suitable shapes are possible. 3. A magnetic induction pressure sensor according to claim 1, wherein the upper cover cylinder and the lower cover can be circular or square, or in other shapes. 4. A magnetic induction pressure sensor according to claim 1, wherein the shape of the printed circuit board can be made into other suitable shapes according to actual needs. 5. The magnetic induction pressure sensor according to claim 1, wherein the number of resistors and reed switches on the printed circuit board can be increased or decreased according to the requirement of accuracy. 6. The magnetic induction pressure sensor according to claim 1, wherein the shape of the present invention can be circular or other shapes. 7. A magnetic induction pressure sensor according to claim 1, wherein the present invention On the printed circuit on the printed circuit board, TP points can be added at the required positions to provide a pressure warning device. 8. A magnetic induction pressure sensor according to claim 1, characterized in that, the interior of the present invention can be injected with suitable insulating oil or silicone oil, which can be used for rust prevention of internal components, and also has buffer and The function of absorbing external vibration. 9. A magnetic induction pressure sensor according to claim 1, characterized in that, for the selection of the terminal, a terminal with 2 contacts can be used. 10. The magnetic induction pressure sensor according to claim 1, characterized in that, the selection of the connection terminal is matched with the setting of the warning point, and the connection terminal with 3 contacts can be selected for application. 11. A magnetic induction pressure sensor according to claim 7, wherein the printed circuit board of the present invention is provided with a TP warning point, and a magnetic reed switch can also be used to cooperate with the circuit to provide a warning function. 1 2 . A magnetic induction pressure sensor, characterized in that its structure includes the following components: a connection terminal part, which is composed of an insulating gasket and a connection terminal, for providing signal output; a cylinder body for A cylindrical cover, with a round hole at the central upper end, for the purpose of accommodating the connecting terminal; a pointer, whose shape is slightly inverted L, with a round hole at the lower end for combining with the central rotating shaft, and a round hole at the other end. The magnet is used to provide the magnetic field induced by the reed switch; A ring-shaped sheet on which a circuit is printed, and the circuit is provided with a resistor and a reed switch. When the magnet on the pointer passes by and induces the reed switch, the two reed pieces in the reed switch are closed, and the conduction includes the resistor. The series circuit can be used to read different resistance signals, so as to know the displacement of the Baden tube under pressure, and then read the value of the pressure; The seat body forms a hollow shell outside, which is used to provide a ring-shaped film installation, and then combined with the transmission mechanism by means of a fixing element; A transmission mechanism, which includes a curved transmission tooth piece, a transmission rod, a convex transmission piece, a hairspring, a central shaft gear, a central shaft, and a pin, is combined by a trapezoidal top piece, a fixing screw, a support piece, and a bottom plate to form a transmission mechanism ; an O-ring, and The bottom cover is a bottom cover with a square hole in the center; With the above-mentioned components stacked in layers, with such a structure, the Baden tube is pressed to produce a uniform deformation, which drives the transmission mechanism together to make the pointer move on the printed circuit on the annular sheet, and because of the magnet on the pointer, the printed circuit is induced The different magnetic reed switches on the circuit are used to conduct the series circuit formed by the magnetic reed switch and the resistor on the printed circuit, and use the terminal to transmit the signal to read the pressure on the instrument. 13. The magnetic induction pressure sensor according to claim 1, wherein a printed circuit board is used, or it can be applied in other suitable forms. 14. A magnetic induction pressure sensor according to claim 12, characterized in that, the ring-shaped thin printed circuit is used, or it can be applied in other suitable forms. 15. A magnetic induction pressure sensor according to claim 12, characterized in that, the shape of the base body can be manufactured and used in conjunction with an applicable shape.