阅读说明：本技术 无线式螺栓预紧力传感器 (Wireless bolt pretightening force sensor ) 是由 罗少轩 乔爱民 汤庆国 于 2019-02-26 设计创作，主要内容包括：本发明公开了一种无线式螺栓预紧力传感器,包括轮辐式弹性体和内腔,所述的轮辐式弹性体的一端与螺栓的垫片紧密接触、另一端与联接部件紧密接触；所述的轮辐式弹性体上沿轴心均匀对称的加工有8个圆孔,每两个圆孔之间的剪切梁两侧皆贴有金属箔式应变片,并组成惠斯通电桥结构；传感器的内腔设置有与金属箔式应变片连接的信号处理电路,所述的信号处理电路与无线发射电路连接。无需信号传输线缆,避免联接部件带着螺栓和传感器连续旋转时,传感器线缆发生缠绕和绷断。(The invention discloses a wireless bolt pre-tightening force sensor which comprises a spoke type elastic body and an inner cavity, wherein one end of the spoke type elastic body is in close contact with a gasket of a bolt, and the other end of the spoke type elastic body is in close contact with a connecting part; the spoke type elastic body is uniformly and symmetrically processed with 8 round holes along the axis, and metal foil type strain gauges are pasted on two sides of the shearing beam between every two round holes to form a Wheatstone bridge structure; the inner cavity of the sensor is provided with a signal processing circuit connected with the metal foil type strain gauge, and the signal processing circuit is connected with the wireless transmitting circuit. Need not signal transmission cable, avoid the hookup part to take bolt and sensor continuous rotation time, the sensor cable takes place to twine and stretch out absolutely.)

1. The utility model provides a wireless formula bolt pretightning force sensor which characterized in that: the elastic body comprises a spoke type elastic body (1) and an internal cavity (8), wherein one end of the elastic body (1) is in tight contact with a gasket (12) of a bolt (11), and the other end of the elastic body is in tight contact with a connecting part (14); the spoke type elastic body (1) is provided with 8 symmetrical round holes (2), the area between every two adjacent round holes forms a strain beam (3) which forms 8 strain beams in total, and two sides of each strain beam are respectively stuck with 1 metal foil type strain sheet (7) to form a Wheatstone bridge structure; the inner cavity (8) is provided with a signal processing circuit connected with the metal foil type strain gauge (7), and the signal processing circuit is connected with the wireless transmitting circuit.

2. The wireless bolt pretension sensor according to claim 1, wherein: inner chamber (8) are located the rear portion of spoke formula elastomer (1), and internally mounted has signal processing and wireless communication device, include: a signal processing circuit board (9) and a rechargeable lithium battery (10); the signal processing circuit board (9) is annular and coaxial with the spoke type elastic body (1) and is fixed by epoxy resin; the communication antenna (15) is led out through an antenna hole (5) in the sensor shell (4), and after the antenna (15) is led out, waterproof sealing treatment is carried out on the inner side and the outer side of the antenna hole (5) through waterproof glue; the rechargeable lithium battery (10) is arranged in the inner cavity (8) and is positioned at the rear part of the signal processing circuit board (9), and a charging interface of the lithium battery is connected with a waterproof charging interface (6) on the sensor shell.

3. The wireless bolt pretension sensor according to claim 2, wherein: the Wheatstone bridge signal output circuit comprises a connecting terminal JP1 connected with the metal foil type strain gauge, pins 2 and 1 of the connecting terminal JP1 are respectively connected with a power supply VCC and GND, pins 4 and 3 of the connecting terminal JP1 respectively output an S + signal and an S-signal through resistors R1 and R2, output ends of the resistors R1 and R2 are respectively connected with capacitors C1 and C2, and the capacitors C1 and C2 are commonly connected with a ground wire.

4. The wireless bolt pretension sensor according to claim 2, wherein: the singlechip circuit comprises a singlechip U2, and pins 1 and 2 of the singlechip U2 are connected with output signals S + and S-of the Wheatstone bridge; a voltage source VCC is respectively connected with capacitors C4, C5 and a resistor R4 through a resistor R3, the capacitors C4 and C5 are commonly connected with a ground wire, and the resistor R3 is connected with a pin 12 of a singlechip U2; a resistor R5 and a crystal oscillator Y1 are connected in parallel between pins 15 and 16 of the singlechip U2, pins 1 and 2 of the crystal oscillator Y1 are respectively connected with capacitors C6 and C7, and the capacitors C6 and C7 are connected with a ground wire together: pins 3 and 4 of the JTAG interface JP3 are connected with pins 11 and 12 of the single chip microcomputer U2 respectively.

5. The wireless bolt pretension sensor according to claim 2, wherein: the wireless transmitting circuit comprises a singlechip U2, and pins 19, 20, 25 and 14 of a singlechip U5 of pins 3, 4, 8 and 9 of the singlechip U2 are connected.

6. The wireless bolt pretension sensor according to claim 1, wherein: the inner cavity (8) is further provided with a power supply circuit, the power supply circuit comprises a rechargeable lithium battery and a connecting terminal JP2 connected with the positive electrode and the negative electrode of the lithium battery, a pin 2 of the connecting terminal JP2 is connected to a pin 2 of a linear voltage stabilizer U1 through a switch S1 and a diode VD1, the pin 2 of the linear voltage stabilizer U1 is connected with the positive electrode of a tantalum capacitor E1, a pin 3 of the linear voltage stabilizer is respectively connected with the positive electrode of the tantalum capacitor E2 and a nonpolar capacitor C1, and the negative electrode of the tantalum capacitor E1, the negative electrode of the tantalum capacitor E2, the nonpolar capacitor C1, a pin 1 of the linear voltage stabilizer U1 and a pin 1 of the connecting terminal JP1 are connected together and then connected to the negative electrode GND of a power supply.

Technical Field

The invention belongs to the field of bolt pretightening force measurement, and particularly relates to a wireless bolt pretightening force sensor.

Background

The bolt pretightening force is an acting force between the bolt and the connecting part along the axial lead direction of the bolt in the bolt screwing process. In the operation process of industrial equipment, the bolts can be loosened due to vibration of the equipment and the like, so that the connection part falls off and safety accidents are caused, and therefore, the measurement of the pretightening force of the bolts is very important for safe and reliable operation of the industrial equipment. At present, a torque wrench and an annular sensor are mainly used for measuring the pretightening force of the bolt, the torque wrench is used for pretightening the bolt to a fixed force value in a manual mode, but whether a certain bolt is loosened or not can not be detected in real time, only a mode of regularly checking one by one can be adopted, and the detection efficiency and the real-time performance are low; the annular sensor is installed between bolt and hookup part, can real-time detection bolt pretightning force, and detection efficiency and real-time are than higher, but because adopt wired connection mode between annular sensor and the display instrument, consequently the part at bolt place under test can not freely continuous rotation, because the cable can take place to twine when continuous rotation and even break, consequently use on the hookup part that needs continuous rotation such as aerogenerator's blade has very big limitation.

Disclosure of Invention

The invention aims to provide a wireless bolt pretightening force sensor which can be used on a continuously rotating connecting component, does not need a signal transmission cable between the sensor and a display instrument, can remotely transmit a pretightening force signal, and can be used for the connecting component which has a large number of bolts, is easy to loosen and can continuously rotate, such as blades of a wind driven generator.

In order to achieve the purpose, the invention adopts the following technical scheme: a wireless bolt pretightening force sensor comprises a spoke type elastic body and an inner cavity, wherein the inner cavity is positioned below the elastic body, and a signal processing circuit and a wireless communication device are installed in the inner cavity. The sensor is arranged between the gasket of the bolt and the connecting part; the bolt, the gasket, the sensor and the threaded hole on the connecting component are coaxial, the top of the sensor is in contact with the bottom of the gasket, and the bottom of the sensor is in contact with the top of the connecting component;

the spoke type elastic body is provided with 8 symmetrical round holes, the area between every two adjacent round holes forms 1 strain beam, 8 strain beams are formed in total, 1 metal foil type strain gauge is pasted on each of two sides of each strain beam, and a symmetrical Wheatstone bridge structure is formed jointly.

The inner chamber is located the rear portion of spoke formula elastomer, and internally mounted has wireless communication device, includes: the system comprises a signal processing circuit board, a wireless communication module and a rechargeable lithium battery; the signal processing circuit board is annular and coaxial with the spoke type elastic body and is fixed by epoxy resin; the wireless communication module is fixed on the signal processing circuit board through a single row of contact pins, the communication antenna is led out through an antenna hole in the sensor shell, and after the antenna is led out, waterproof sealing treatment is carried out on the inner side and the outer side of the antenna hole through waterproof glue; the rechargeable lithium battery is arranged in the inner cavity and positioned at the rear part of the signal processing circuit board, and a charging interface of the lithium battery is connected with a waterproof charging interface on the sensor shell.

The signal processing circuit board comprises a Wheatstone bridge signal output circuit, a single chip circuit, a wireless communication circuit and a power circuit; the Wheatstone bridge signal output circuit comprises a connecting terminal JP1 connected with the metal foil type strain gauge, pins 2 and 1 of the connecting terminal JP1 are respectively connected with a power supply VCC and GND, pins 4 and 3 of the connecting terminal JP1 respectively output an S + signal and an S-signal through resistors R1 and R2, output ends of the resistors R1 and R2 are respectively connected with capacitors C1 and C2, and the capacitors C1 and C2 are commonly connected with a ground wire;

the singlechip circuit comprises a singlechip U2, and pins 1 and 2 of the singlechip U2 are connected with output signals S + and S-of the Wheatstone bridge; a voltage source VCC is respectively connected with capacitors C4, C5 and a resistor R4 through a resistor R3, the capacitors C4 and C5 are commonly connected with a ground wire, and the resistor R3 is connected with a pin 12 of a singlechip U2; a resistor R5 and a crystal oscillator Y1 are connected in parallel between pins 15 and 16 of the single chip microcomputer U2, pins 1 and 2 of the crystal oscillator Y1 are respectively connected with capacitors C6 and C7, and the capacitors C6 and C7 are connected with a ground wire together; pins 3 and 4 of the JTAG interface JP3 are connected with pins 11 and 12 of the single chip microcomputer U2 respectively.

The wireless communication circuit comprises a wireless communication module U1, wherein pins 3, 4, 8 and 9 of the wireless communication module U1 are respectively connected with pins 19, 20, 25 and 14 of the singlechip U2, pin 2 of the wireless communication module U1 is connected with a power supply VCC, and pins 2 and 5 of the wireless communication module U1 are connected with GND together.

The signal processing circuit board is further provided with a power circuit, the power circuit comprises a rechargeable lithium battery and a connecting terminal JP2 connected with the positive electrode and the negative electrode of the lithium battery, a pin 2 of the connecting terminal JP2 is connected to a pin 2 of a linear voltage stabilizer U1 through a switch S1 and a diode VD1, the pin 2 of the linear voltage stabilizer U1 is connected with the positive electrode of a tantalum capacitor E1, a pin 3 of the linear voltage stabilizer is respectively connected with the positive electrode of the tantalum capacitor E2 and a nonpolar capacitor C1, and the negative electrode of the tantalum capacitor E1, the negative electrode of the tantalum capacitor E2, the nonpolar capacitor C1, a pin 1 of the linear voltage stabilizer U1 and a pin 1 of the connecting terminal JP1 are connected together and then connected to a power supply negative electrode GND.

In the technical scheme, the real-time accurate detection of the bolt pre-tightening force can be effectively realized, and because the lithium battery power supply, the signal processing and the wireless transmitting circuit are added in the sensor, and a power supply cable and a signal transmission cable are not needed between the sensor and the display instrument, the problems of winding and stretch-breaking of the cable when the sensor continuously rotates along with an installation part are solved, so that the sensor can be installed on parts such as blades of a wind driven generator, which have a large number of bolts and are easy to loosen and can continuously rotate; meanwhile, different communication frequencies and communication protocols can be selected in a wireless communication mode according to actual working conditions, the distance between the display instrument and the sensor can be far, the adjustment can be freely carried out, and the field wiring difficulty and the construction cost are reduced.

Drawings

FIG. 1 is a diagram of the outline of a bolt pretension sensor;

FIG. 2 is a cross-sectional view of a bolt pretension sensor;

FIG. 3 is a front view of the present invention in installation;

FIG. 4 is a functional block diagram of the present invention;

FIG. 5 is a schematic diagram of a lithium battery power supply circuit according to the present invention;

FIG. 6 is a schematic diagram of a Wheatstone bridge signal output circuit according to the present invention;

FIG. 7 is a schematic diagram of a wireless communication circuit according to the present invention;

fig. 8 is a schematic diagram of a single chip microcomputer circuit in the invention.

Detailed Description

The invention is further described with reference to the accompanying drawings 1-8:

the shape of the wireless bolt pre-tightening force sensor is as shown in figure 1, the wireless bolt pre-tightening force sensor is of a cylindrical structure, 8 circular holes 2 are symmetrically and uniformly distributed in the top of a spoke type elastic body 1 along the axis, a shearing beam 3 is formed between every two circular holes, the number of the shearing beams 3 is 8, the shearing beams are symmetrically and uniformly distributed along the axis of the elastic body, and a lithium battery charging hole 5 and an antenna leading-out hole 6 are formed in the outer wall of a sensor shell 4.

The internal structure of the wireless bolt pre-tightening force sensor is shown in fig. 2, two side surfaces of the shearing beam 3 are adhered with metal foil type strain gauges 7, and the number of the shearing beams 3 is 8, so that the number of the metal foil type strain gauges is 16, and a Wheatstone bridge structure is formed; the lower part of the sensor is provided with an inner cavity 8 for installing a signal processing circuit board 9 and a lithium battery 10; and a lithium battery charging hole 5 and an antenna leading-out hole 6 are formed in the inner wall of the inner cavity 8 and are communicated with the outer wall of the sensor shell 4.

In a preferred embodiment of the invention, the sensor is mounted as shown in fig. 3: the sensor 13 is mounted between the washer 12 of the bolt 11 and the coupling part 14; the threaded holes in the bolt 11, the gasket 12, the sensor 13 and the coupling component 14 are coaxial, the top of the sensor 13 is in contact with the bottom of the gasket 12, and the bottom of the sensor 13 is in contact with the top of the coupling component 14; the antenna 15 is located on the outer wall of the sensor 13. When the bolt 11 is pre-tightened, because the bolt 11, the gasket 12, the sensor 13 and the coupling component 14 are tightly connected, the elastic body 1 of the sensor 13 is pressed by the gasket 12 and the coupling component 14, so that the elastic body 1 is slightly deformed, the output voltage of a Wheatstone bridge consisting of the metal foil type strain gauges 7 adhered to the shearing beam 3 is correspondingly changed, the change of the voltage and the pressing force between the gasket 12 and the coupling component 14, namely the pre-tightening force of the bolt, are approximately in a linear relation, and the pre-tightening force of the bolt can be detected by detecting the change of the voltage.

The working principle of the wireless bolt pre-tightening force sensor is shown in fig. 4, and a signal output by a Wheatstone bridge consisting of the metal foil type strain gauges 7 is a mV level voltage signal which is weak, so that an interference signal is removed through circuit conditioning and then the signal is sent to a 24-bit AD converter inside a singlechip C8051F350 for AD conversion; the singlechip U2 carries out data processing on the AD conversion result, calculates a specific numerical value of the corresponding bolt pretightening force, and then stores the pretightening force numerical value into a data frame to be sent; the single chip microcomputer U2 drives the wireless transmitting circuit to send out the data frame containing the pretightening force value, the remote wireless receiving circuit module receives the data frame and transmits the data frame to the display instrument, and the display instrument analyzes the data frame, extracts the bolt pretightening force value and displays the bolt pretightening force value on the instrument display screen.

Fig. 5 is a schematic diagram of a power supply circuit of a lithium battery in the invention, in the diagram, a JP2 terminal is used for connecting the positive electrode and the negative electrode of the lithium battery, a switch S1 can be disconnected when a mechanical arm 5 does not work, so that the electric quantity of the lithium battery is saved, a diode VD1 is used for reverse connection prevention protection, a diode VD1 is turned on during normal work, and when a user mistakenly connects the positive electrode and the negative electrode of the lithium battery to the reverse direction, the diode is turned off in the reverse direction; the tantalum capacitors E1 and E2 play a role in energy storage and low-frequency filtering, and the nonpolar capacitor C3 is mainly used for filtering high-frequency noise. Because the lithium battery is used for supplying power, the linear voltage stabilizer U3 adopts the HT7133 with low power consumption, has the characteristics of small volume and low power consumption, is suitable for a lithium battery power supply system, has the HT7133 output voltage of 3.3V, and is represented by VCC and GND in a circuit diagram.

FIG. 6 is a schematic diagram of a signal output circuit of the bridge of the present invention, in which a Wheatstone bridge composed of metal foil type strain gauges 7 is connected to the circuit through a connection terminal JP1, pins 1 and 2 of JP1 are power supply pins of the Wheatstone bridge, and pins 3 and 4 of JP2 are signal output pins of the Wheatstone bridge; the output signals of the Wheatstone bridge are mV differential voltage signals, and the resistor R1, the capacitor C1, the resistor R2 and the capacitor C2 respectively form an RC low-pass filter for filtering high-frequency noise and interference signals in the differential signals, the differential signals output by the Wheatstone bridge consisting of the metal foil type strain gauges 7 are output to analog input pins 1 and 2 of a singlechip U2 in the figure 8 after being subjected to RC low-pass filtering, are amplified by a 128-time programmable amplifier in the singlechip, and are converted into corresponding digital signals by a 24-bit AD converter in the singlechip U2.

Fig. 7 is a schematic diagram of a wireless transmitting circuit of the invention, and the wireless transmitting module adopts the model of RN630, and is characterized by small volume, low power consumption, barrier-free transmission distance of about 500 m, and a circuit interface of the wireless transmitting module is a 9-core single-row pin. The figure is represented by U1, pins 1 and 2 are power supply terminals of a wireless transmitting module and are connected with a 3.3V power supply VCC and GND; pins 4 and 3 are communication pins RXD and TXD of the wireless transmitting module and the singlechip U5, and the communication adopts a serial mode and TTL level and is respectively connected with pins 20 and 19 of the singlechip U5; a pin 5 of the wireless transmitting module is also a grounding pin, pins 6 and 7 are also serial communication pins, and the RS232 level is not used in the system, so that the wireless transmitting module is suspended; the pin 8 is a sleep control pin and is connected with the pin 25 of the singlechip, and when data is not sent, the singlechip U4 enters a sleep power-saving mode through the pin control module, so that the electric quantity of a battery can be saved; the pin 9 is a reset pin of the module and is connected with the pin 14 of the singlechip, and the singlechip U2 can reset the wireless transmission module through the pin if necessary.

FIG. 8 is a schematic diagram of a signal amplification circuit of the invention, which is also a schematic diagram of a minimum system circuit of a single chip microcomputer U2, wherein the single chip microcomputer U2 adopts C8051F350, a 128-time programmable amplifier and a 24-bit AD converter are arranged in the single chip microcomputer U2, the power consumption is low, pins 1-8 of the single chip microcomputer are analog input pins, and pins 1 and 2 are connected with signal output of a sensor Wheatstone bridge; pins 31 and 32 of the singlechip are reference voltage input pins of an internal AD converter, and are connected with a 3.3V power supply VCC and GND in the figure; pins 21 and 22 are power input pins of an internal digital device, and are connected with 3.3V power supplies VCC and GND in the figure; pins 9 and 10 are power input pins of an internal analog device, and are connected with a 3.3V power supply VCC and GND in the figure; the resistors R3 and R4 and the capacitors C4 and C5 form a power-on reset circuit of the singlechip U2, and are connected with a No. 12 pin of the singlechip, so that the automatic reset operation is carried out on the singlechip U2 when the system is powered on; JP3 is a JTAG interface of a single chip microcomputer, pins 1 and 2 are power supplies, pins 3 and 4 are respectively connected to pins 11 and 12 of the single chip microcomputer (pin 12 is also a reset pin of a single chip microcomputer U2), JP3 mainly functions to program a compiled program into the single chip microcomputer U5 and to perform online debugging on the single chip microcomputer U5; the resistor R5, the crystal oscillator Y1, the capacitors C6 and C7 jointly form an oscillation circuit, and the oscillation circuit is connected with pins 15 and 16 of a singlechip U2; the pins 14, 25, 20 and 19 of the singlechip U2 are connected with the pins 9, 8, 3 and 4 of the wireless transmitting module U1 to control the working state of the wireless transmitting module U1 and communicate with the wireless transmitting module U1.

In conclusion, the invention can effectively realize the accurate measurement of the bolt pretightening force and solve the problem of real-time detection of the bolt pretightening force, and because the lithium battery power supply, the signal processing and the wireless transmitting circuit are added in the sensor, a power supply cable and a signal transmission cable are not needed between the sensor and the display instrument, the problems of winding and stretch-breaking of the cable when the sensor continuously rotates along with the installation part are solved, so the sensor can be installed on parts, such as blades of a wind driven generator, with more bolts, easy loosening of the bolts and continuous rotation; meanwhile, different communication frequencies and communication protocols can be selected in a wireless communication mode according to actual working conditions, the distance between the display instrument and the sensor can be far, the adjustment can be freely carried out, and the field wiring difficulty and the construction cost are reduced.