A piezoelectric pressure sensor for explosion fields

Abstract

This invention discloses a piezoelectric pressure sensor for an explosion field. The sensor includes a housing and a diaphragm, a force transmission block, two piezoelectric crystals, an inertial compensation mass block, and electrode plates mounted on and inside the housing. When the sensor is subjected to shock wave pressure, the two piezoelectric crystals generate positive charges on their upper surfaces and negative charges on their lower surfaces. Since the two piezoelectric crystals are connected in series, the sensor outputs a voltage signal proportional to the shock wave pressure. When the sensor is subjected to acceleration, the inertial compensation mass block exerts opposite forces on the two piezoelectric crystals, causing them to generate opposite voltage signals, thus compensating for acceleration-induced parasitic output signals.

Description

Technical Field

[0001] This invention relates to the field of piezoelectric pressure sensor technology, specifically to an explosion field piezoelectric pressure sensor. Background Technology

[0002] During the explosion and combustion process, warheads are often accompanied by strong mechanical shock and vibration, thermal shock, electromagnetic waves and other parasitic effects. These parasitic effects will cause certain parasitic outputs to shock wave pressure sensors and acceleration sensors. Especially in the near field of the explosion, the interference signal is superimposed on the air shock wave signal, causing distortion of the measured shock wave signal, which seriously affects the measurement of the shock wave and will cause the high shock acceleration sensor to produce a serious lateral parasitic output.

[0003] Mechanical vibration and shock are the most significant parasitic effects in shock wave measurement. Under destructive conditions, strong mechanical shocks include seismic waves and mechanical shocks from the sensor mounting plate. Most currently used piezoelectric shock wave pressure sensors do not have inertial compensation structures. Piezoelectric shock wave pressure sensors are particularly sensitive to mechanical shocks and seismic waves, and their output values ​​may even be larger than the output values ​​under actual pressure excitation. At the same time, they will also excite high-frequency modes of the sensor system. If no corresponding measures are taken, the measured shock wave pressure signal will inevitably be severely distorted.

[0004] Existing piezoelectric pressure sensors with inertial compensation function are all charge output type. The compensation crystal group structure requires four piezoelectric crystals, which greatly increases the assembly difficulty of the crystal group and requires extremely high processing quality of the crystals. If the crystal thickness is too thin, it is easy to break during assembly; if the crystal thickness is too thick, it will greatly reduce the natural frequency of the sensor. Summary of the Invention

[0005] In view of the defects or deficiencies of the prior art, the present invention provides an explosion field piezoelectric pressure sensor.

[0006] Therefore, the piezoelectric pressure sensor for explosion fields provided by the present invention includes a housing and leads. The housing has a component receiving cavity, and a sensing opening is provided at one axial end of the component receiving cavity. A diaphragm is provided at the sensing opening. An insulating film, a force transmitting block, a first piezoelectric crystal, an inertial compensation mass block, an electrode plate, and a second piezoelectric crystal are installed in the component receiving cavity. The diaphragm, insulating film, force transmitting block, first piezoelectric crystal, inertial compensation mass block, electrode plate, and second piezoelectric crystal are arranged sequentially along the axial direction. At the same time, the positive electrode of the first piezoelectric crystal is close to the insulating film and the negative electrode is close to the inertial compensation mass block, and the positive electrode of the second piezoelectric crystal is close to the electrode plate and the negative electrode is close to the housing, so that the first piezoelectric crystal and the second piezoelectric crystal are connected in series.

[0007] The force transmission block, the first piezoelectric crystal, the inertial compensation mass block, the electrode sheet, and the second piezoelectric crystal form a crystal stack, and an insulating ring is provided between the side wall of the crystal stack and the inner wall of the component receiving cavity.

[0008] The lead wire passes through the housing and the second piezoelectric wafer and connects to the electrode plate.

[0009] An alternative approach is that the axial thickness of the inertial compensation mass block is three times the axial thickness of the force transmission block, and the axial thickness of the first piezoelectric wafer is twice the axial thickness of the second piezoelectric wafer.

[0010] An alternative approach is to use steel for the diaphragm, force transmission block, and inertial compensation mass block; to use quartz crystal for the first and second piezoelectric wafers; and to use copper for the electrode sheet.

[0011] Alternatively, the insulating film can be adhered to the lower surface of the diaphragm.

[0012] Alternatively, the lead wire and the electrode sheet can be connected by welding.

[0013] Alternatively, the diaphragm can be welded to the housing.

[0014] An alternative is that the housing is assembled from an upper housing and a lower housing, the upper housing having a component receiving cavity, and the lead wire passing through the lower housing and the second piezoelectric wafer to connect to the electrode sheet.

[0015] The inertial compensation mass block in the pressure sensor crystal group structure of the present invention is used to compensate for parasitic output caused by acceleration and has an inertial compensation function; and the crystal group includes two piezoelectric crystals connected in series to output voltage signals. The small number of piezoelectric crystals reduces the assembly difficulty and has little impact on the sensor's natural frequency, thus ensuring the dynamic performance of the piezoelectric pressure sensor. Attached Figure Description

[0016] Figure 1 This is a cross-sectional structural diagram of the explosion field piezoelectric pressure sensor of the present invention.

[0017] Figure 2 This is the pressure output response of the piezoelectric pressure sensor in the explosion field in this embodiment of the invention. Detailed Implementation

[0018] Unless otherwise stated, the terms or methods in this document are based on the understanding of those skilled in the art or implemented using existing methods.

[0019] The axial, downward, and other directional or orientational terms used herein are consistent with those in the accompanying drawings. It should be noted that the accompanying drawings are intended to explain the present invention, and any solutions obtained by those skilled in the art through equivalent transformations are within the scope of this invention.

[0020] See Figure 1 As shown, the explosion field piezoelectric pressure sensor of the present invention includes a housing, a component receiving cavity inside the housing, a diaphragm 1 at the sensing opening at the axial end of the component receiving cavity, and an insulating film 2, a force transmission block 3, a first piezoelectric crystal 4, an inertial compensation mass block 5, an electrode sheet 6 and a second piezoelectric crystal 7 arranged sequentially in the receiving cavity along the axial direction.

[0021] Wherein: diaphragm 1 is fixed to the induction opening at the axial end of the component receiving cavity, and insulating film 2 is bonded to the lower surface of diaphragm 1 to isolate the positive charge generated by the first piezoelectric crystal 4; the first piezoelectric crystal 4 is a non-porous crystal and the second piezoelectric crystal 7 is a porous crystal, for the lead wire 11 to pass through and connect to the electrode sheet 6.

[0022] The first piezoelectric crystal 4 and the second piezoelectric crystal 7 are connected in series, that is, the positive electrode of the first piezoelectric crystal 4 is close to the insulating film 2 and the negative electrode is close to the inertial compensation mass block 5, the positive electrode of the second piezoelectric crystal 7 is close to the electrode plate 6 and the negative electrode is close to the shell or the inner wall of the cavity; since the first piezoelectric crystal 4 and the second piezoelectric crystal 7 are connected in series, the electrode plate 6 outputs a voltage signal.

[0023] The force transmission block 3, the first piezoelectric crystal 4, the inertial compensation mass block 5, the electrode sheet 6, and the second piezoelectric crystal 7 form a crystal stack and are coaxially stacked in the receiving cavity. An insulating ring 8 is provided between the side wall of the crystal stack and the inner wall of the receiving cavity to ensure the insulation of the sensor.

[0024] Lead 11 passes through the housing and the second piezoelectric wafer is soldered to the electrode plate 6.

[0025] The working principle of the explosion field piezoelectric pressure sensor of the present invention is as follows:

[0026] When the shock wave pressure acts on the sensor, the shock wave pressure is transmitted sequentially through the diaphragm 1, the force transmission block 3, the first piezoelectric crystal 4, the inertial compensation mass block 5, the electrode plate 6, and the second piezoelectric crystal 7. Each structural component is subjected to the shock wave pressure. The first piezoelectric crystal 4 generates a positive charge on its upper surface and a negative charge on its lower surface. Similarly, the second piezoelectric crystal 7 generates a positive charge on its upper surface and a negative charge on its lower surface. Since the first piezoelectric crystal 4 and the second piezoelectric crystal 7 are connected in series, the electrode plate 6 outputs a voltage signal proportional to the shock wave pressure, which is output through the lead 11.

[0027] When the sensor is subjected to acceleration (especially acceleration in the same direction as and opposite to the shock wave pressure), the sensor as a whole is subjected to force, that is, the diaphragm 1, force transmission block 3, first piezoelectric crystal 4, inertial compensation mass block 5, electrode plate 6, and second piezoelectric crystal 7 are all subjected to inertial force. At this time, the inertial compensation mass block 5 will generate opposite forces on the first piezoelectric crystal 4 and the second piezoelectric crystal 7, for example, generating tensile stress on the first piezoelectric crystal and compressive stress on the second piezoelectric crystal; or, generating compressive stress on the first piezoelectric crystal and tensile stress on the second piezoelectric crystal, thereby causing the first piezoelectric crystal 4 and the second piezoelectric crystal 7 to generate opposite voltage signals, thereby compensating for the parasitic acceleration output signal.

[0028] To ensure that the inertial compensation mass block 5 exerts opposing forces on the first piezoelectric crystal 4 and the second piezoelectric crystal 7 under the influence of external acceleration, in a preferred embodiment, the axial structural dimensions or axial thickness ratios of the force transmission block 3, the inertial compensation mass block 5, the first piezoelectric crystal 4, and the second piezoelectric crystal 7 can be optimized. For example, the axial thickness of the inertial compensation mass block 5 is three times the axial thickness of the force transmission block 3, and the axial thickness of the first piezoelectric crystal 4 is twice the axial thickness of the second piezoelectric crystal 7.

[0029] In the specific design, the shapes and structures of the diaphragm 1, insulating film 2, force transmission block 3, first piezoelectric crystal 4, inertial compensation mass block 5, electrode sheet 6, and second piezoelectric crystal 7 are determined according to the sensor housing structure, and are commonly circular or cylindrical.

[0030] In the specific design, the diaphragm 1, the force transmission block 3, and the inertial compensation mass block 5 can be made of high-strength steel; the first and second piezoelectric crystals can be made of quartz crystal; and the electrode sheet 6 can be made of copper.

[0031] Example:

[0032] In this embodiment, the piezoelectric pressure sensor housing is assembled from an upper housing 9 and a lower housing 10 (specifically, it can be assembled by welding). The upper housing has a component receiving cavity. The inner diameter of the component receiving cavity in the housing 9 is 3.9 mm. The axial thickness of the diaphragm 1 is 0.2 mm, the thickness of the insulating film 2 is 0.2 mm, the thickness of the force transmission block 3 is 0.5 mm, the thickness of the first piezoelectric crystal 4 is 0.4 mm, the thickness of the inertial compensation mass block 5 is 1.5 mm, the thickness of the electrode sheet 6 is 0.1 mm, and the thickness of the second piezoelectric crystal 7 is 0.2 mm. The cross-section of each component is circular.

[0033] In this embodiment, the diaphragm 1, force transmission block 3, and inertial compensation mass block 5 are made of maraging steel; the first and second piezoelectric wafers are made of quartz crystal; and the electrode sheet 6 is made of copper.

[0034] The sensor in this embodiment was simulated and analyzed using the finite element method. The simulation conditions were as follows: the sensor body was set as a fixed constraint, a pressure load of 0-1 MPa was applied in the vertical direction of the sensor diaphragm, and the voltage output signal of the electrode plate was the output signal of the sensor. The pressure output response of the sensor in this embodiment was as follows. Figure 2 As shown, this result indicates that the sensor's pressure sensitivity is 39.7 V / MPa.

Claims

1. An explosion field piezoelectric pressure sensor comprising a case and a lead wire (11), a component housing cavity being provided in the case, characterized in that, The axial end of the assembly accommodating cavity is provided with an induction opening, and the induction opening is provided with a diaphragm (1). The assembly accommodating cavity is provided with an insulating film (2), a force block (3), a first piezoelectric wafer (4), an inertial compensation mass block (5), an electrode sheet (6) and a second piezoelectric wafer (7) in sequence along the axial direction. The positive electrode of the first piezoelectric wafer is close to the insulating film, the negative electrode is close to the inertial compensation mass block, the positive electrode of the second piezoelectric wafer is close to the electrode sheet, and the negative electrode is close to the shell, so that the first piezoelectric wafer and the second piezoelectric wafer are connected in series. The force block (3), the first piezoelectric wafer (4), the inertial compensation mass block (5), the electrode sheet (6) and the second piezoelectric wafer (7) form a crystal pile, and an insulating ring (8) is arranged between the side wall of the crystal pile and the inner wall of the assembly accommodating cavity. The lead wire is connected with the electrode sheet through the shell and the second piezoelectric wafer.

2. The blast field piezoelectric pressure sensor according to claim 1, characterized by, The axial thickness of the inertial compensation mass block (5) is 3 times the axial thickness of the force block (3), and the axial thickness of the first piezoelectric wafer (4) is 2 times the axial thickness of the second piezoelectric wafer (7).

3. The blast field piezoelectric pressure sensor of claim 1, wherein, The diaphragm (1), the force block (3) and the inertial compensation mass block (5) are made of steel; the first piezoelectric wafer (4) and the second piezoelectric wafer (7) are made of quartz crystal; and the electrode sheet (6) is made of copper.

4. The blast field piezoelectric pressure sensor of claim 1, wherein, The insulating film is bonded to the lower surface of the diaphragm.

5. The blast field piezoelectric pressure sensor of claim 1, wherein, The lead wire is connected with the electrode sheet by welding.

6. The blast field piezoelectric pressure sensor of claim 1, wherein, The diaphragm is welded to the shell.

7. The blast field piezoelectric pressure sensor of claim 1, wherein, The shell is assembled by an upper shell (9) and a lower shell (10), the upper shell is provided with an assembly accommodating cavity, and the lead wire is connected with the electrode sheet through the lower shell and the second piezoelectric wafer.

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