Sensor probe with Z-axis sensitive axis

Abstract

The sensor probe comprises a shell, a circuit board assembly and a cable, a first containing cavity used for containing the circuit board assembly is formed in the shell, and a mounting plane is arranged at the front end of the first containing cavity; the circuit board assembly comprises a first circuit board, a second circuit board and a third circuit board, the first circuit board is tightly attached to the mounting plane, an accelerometer with the sensitive direction as the Z axis is welded to the surface, away from the mounting plane, of the first circuit board, the second circuit board is vertically clamped to the first circuit board, and the third circuit board is connected to the third circuit board. And the first circuit board is connected with the second circuit board through a third circuit board. According to the sensor probe with the Z-axis sensitive axis, the contact area between the shell and the accelerometer with the Z-axis sensitive direction is increased, so that the accelerometer with the Z-axis sensitive direction can receive vibration and impact signals more easily, and the test precision is remarkably improved. And the structure is compact, the occupied space is small, and the requirement for miniaturization of the sensor probe can be met.

Description

Technical Field

[0001] The present application relates to the field of detection technology, and in particular to a sensor probe whose sensitive axis is a Z axis. Background Art

[0002] In the field of vibration impact signal detection and fault diagnosis, foreign comb-tooth MEMS (Micro-electro mechanical systems) accelerometers are now mostly used as the core sensitive devices of sensors. The sensitive axis is in the in-plane direction. The accelerometer with the sensitive direction of the Z axis is mounted horizontally on the PCB and then installed inside the sensor housing along with the PCB. This installation method has a complex signal transmission path. In addition, the sensor structure has a packaging stress effect on the accelerometer with the sensitive direction of the Z axis, resulting in low accuracy in detecting low-frequency and weak vibration impact signals. Compared with the accelerometer with the sensitive axis in the in-plane direction, the accelerometer with the sensitive axis in the out-of-plane direction, also called the Z-axis sensitive direction (sensitive axis is the Z axis), has better performance. The installation direction requirements of such MEMS accelerometers are different from those of the in-plane accelerometers. In actual engineering application scenarios, MEMS accelerometers usually need to be used in conjunction with peripheral circuits. The peripheral circuits are generally printed on a PCB (Printed Circuit Board) and the accelerometers are soldered to the PCB. However, this type of structure usually has a large area, resulting in a larger overall sensor, which cannot meet the requirements for small sensor sizes in some occasions.

[0003] In summary, how to ensure the small size of the sensor while meeting the installation requirements in the Z-axis sensitive direction is a technical problem that technical personnel in this field urgently need to solve. Summary of the invention

[0004] In order to solve the above technical problems, an object of the present invention is to provide a sensor probe with high detection accuracy and a sensitive axis being the Z axis.

[0005] The technical solution provided by the present invention is as follows: A sensor probe with a sensitive axis of the Z axis comprises a shell, a circuit board assembly, and a cable. A first accommodating cavity for accommodating the circuit board assembly is provided inside the shell, and a mounting plane is provided at the front end of the first accommodating cavity; the circuit board assembly comprises a first circuit board, a second circuit board, and a third circuit board. The first circuit board is tightly attached to the mounting plane, and an accelerometer with a sensitive direction of the Z axis is welded on the surface away from the mounting plane. The second circuit board is vertically clamped on the first circuit board, and the first circuit board and the second circuit board are connected through a third circuit board. The third circuit board is a flexible circuit board.

[0006] Preferably, the mounting plane is arranged laterally along the shell and is located at one end of the first accommodating cavity close to the front end. The outer end surface of the shell corresponding to the mounting plane includes an annular cone surface, so that the vibration impact signal generated by the device under test is transmitted to the mounting plane through the annular cone surface on the shell.

[0007] Preferably, a temperature sensitive device is also included. A stud is provided at the front end of the housing for being installed on the device under test through the stud. A second accommodating cavity connected to the first accommodating cavity is provided inside the stud. The temperature sensitive device is accommodated in the second accommodating cavity and is electrically connected to the first circuit board.

[0008] Preferably, the first circuit board is circular, and its diameter is slightly smaller than the inner diameter of the first accommodating cavity.

[0009] Preferably, a plurality of grooves for filling the potting glue are provided on the installation plane.

[0010] Preferably, it also includes a stress isolation cover which is arranged on the accelerometer whose sensitive direction is the Z-axis and is used to isolate the accelerometer whose sensitive direction is the Z-axis from the potting glue filled in the first accommodating cavity.

[0011] Preferably, the second circuit board is vertically clamped on the first circuit board as follows: the first circuit board is provided with a groove, the second circuit board is fixed on the first circuit board through the groove, the groove provided on the first circuit board includes a first groove and a second groove; the second circuit board has a first connecting end and a second connecting end, the first connecting end is inserted into the first groove, and the second connecting end is inserted into the second groove; The first connecting end has an L-shaped structure in the thickness direction for cooperating with the first groove, and the second connecting end has an L-shaped structure in the thickness direction for cooperating with the second groove; or; The first connecting end has an L-shaped structure in the length direction for cooperating with the first groove, and the second connecting end has an L-shaped structure in the length direction for cooperating with the second groove.

[0012] Preferably, the circuit board assembly is provided with a conditioning circuit, and the conditioning circuit comprises: A filter circuit connected to the accelerometer, used for filtering the sampling signal output by the accelerometer; A signal conversion circuit connected to the filter circuit, used to amplify the output of the filter circuit, or to amplify the output of the filter circuit and convert it into voltage or current; An interface protection circuit is connected to the signal conversion circuit and is used for anti-interference, and the output of the interface protection circuit is used as the output of the conditioning circuit to output the detection signal obtained after processing.

[0013] Preferably, the conditioning circuit is arranged on a second circuit board.

[0014] Preferably, the first circuit board and the second circuit board each have N layers, and M layers among the N layers are flexible layers, and the M flexible layers are connected to the corresponding layers of the third circuit board in a one-to-one correspondence; wherein M and N are both positive integers, M represents the number of layers of the third circuit board, N represents the number of layers of the first circuit board and the second circuit board, and M≤N; the second circuit board is used to receive the sampling signal of the accelerometer through the first circuit board and the third circuit board, process the sampling signal through the conditioning circuit, and output the detection signal obtained after processing.

[0015] Preferably, the second circuit board is rectangular, and a relief recess for avoiding the stress isolation cover is provided at the front end.

[0016] Preferably, a stress isolation ring is further included, and a shoulder is provided at the rear end of the second circuit board, and the stress isolation ring is located on the shoulder.

[0017] Preferably, it also includes a sealing locking piece, which is provided with a through hole, and the cable passes through the through hole to be connected to the second circuit board. The sealing locking piece is pressed against the shoulder of the second circuit board to limit the position of the second circuit board and press the first circuit board against the mounting plane, and the stress isolation ring is located between the second circuit board and the sealing locking piece.

[0018] Compared with the prior art, the sensor probe with the sensitive axis of the present invention is the Z axis. By welding the accelerometer with the sensitive direction of the Z axis on the surface of the first circuit board, and the first circuit board is close to the installation plane of the shell, the contact area between the shell and the accelerometer with the sensitive direction of the Z axis is increased, so that the accelerometer with the sensitive direction of the Z axis is easier to receive vibration and impact signals, and the test accuracy is significantly improved. The second circuit board is vertically clamped on the first circuit board, and the first circuit board and the second circuit board are connected through a flexible circuit board, so that the structure is compact, the space occupied is small, and the sensor is miniaturized, which can meet the installation needs of the axle box, motor and other monitoring positions of the rotating parts of the running parts of locomotives and subway vehicles in rail transit. In addition, an annular cone surface is set on the outer end face of the shell corresponding to the installation plane, so that the vibration impact signal generated by the tested device is transmitted to the installation plane through the annular cone surface on the shell, which can simplify the signal transmission path, and also make the accelerometer with the sensitive direction of the Z axis easier to receive vibration and impact signals, and significantly improve the test accuracy. Stress isolation parts (stress isolation cover and stress isolation ring) are also added inside the sensor to reduce the impact of assembly process and ambient temperature changes on MEMS zero-position output, so that the sensor can accurately and stably detect weak vibration and impact signals while meeting the requirements of large-range and wide-frequency response detection. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0020] Figure 1 A three-dimensional composite diagram of a sensor probe according to an embodiment of the present invention; Figure 2 for Figure 1 An exploded perspective view of the sensor probe shown; Figure 3 for Figure 1 An exploded perspective view of the front end portion of the sensor probe shown; Figure 4 for Figure 3 A longitudinal sectional view of the front end portion of the sensor probe shown; Figure 5 for Figure 3 A longitudinal sectional view of the front end of the sensor probe in another direction; Figure 6 for Figure 1 A longitudinal sectional view of the housing in the sensor probe shown; Figure 7 for Figure 6 a cross-sectional view of the housing probe shown; Figure 8 for Figure 1 A three-dimensional combination diagram of a circuit board assembly and an accelerometer in the sensor probe shown; Fig. 9 for Figure 1 A perspective view of a stress isolation cover in the sensor probe shown; Fig.10 for Figure 1 A three-dimensional combined view of another specific embodiment of the circuit board assembly and the accelerometer in the sensor probe; Fig.11 for Figure 1 A schematic diagram of the structure of the conditioning circuit in the sensor probe shown; Fig.12 for Figure 1 A schematic structural diagram of another specific implementation of a conditioning circuit in the sensor probe shown; Fig.13 for Figure 1 A schematic structural diagram of another specific implementation of the conditioning circuit in the sensor probe shown; Fig.14 A three-dimensional assembly diagram of a sensor probe according to another embodiment of the present invention; Fig.15 for Fig.14 An exploded perspective view of the sensor probe shown; Fig.16 for Fig.14 An exploded perspective view of the front end portion of the sensor probe shown; Fig.17 for Fig.16 A longitudinal sectional view of the front end portion of the sensor probe shown; Fig.18 for Fig.16 A longitudinal sectional view of the front end of the sensor probe in another direction is shown. DETAILED DESCRIPTION

[0021] In order to enable those skilled in the art to better understand the technical solutions in this application, the technical solutions in the embodiments of this application will be clearly and completely described below. Obviously, the described embodiments are only part of the embodiments of this application, not all of them. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0022] It should be noted that when an element is referred to as being "fixed on" or "set on" another element, it can be directly on the other element or indirectly set on the other element; when an element is referred to as being "connected to" another element, it can be directly connected to the other element or indirectly connected to the other element.

[0023] It should be understood that the terms "length", "width", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc., indicating the orientation or position relationship, are based on the orientation or position relationship shown in the drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present application.

[0024] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the features. In the description of this application, "multiple" and "several" mean two or more, unless otherwise clearly and specifically defined.

[0025] It should be noted that the structures, proportions, sizes, etc. illustrated in the drawings of this specification are only used to match the contents disclosed in the specification for people familiar with this technology to understand and read, and are not used to limit the conditions under which this application can be implemented. Therefore, they have no substantive technical significance. Any structural modification, change in proportional relationship or adjustment of size should still fall within the scope of the technical content disclosed in this application without affecting the effects and purposes that can be achieved by this application.

[0026] like Figures 1 to 13 As shown, an embodiment of the present invention provides a sensor probe whose sensitive axis is the Z axis, including a housing 11, a circuit board assembly, and a cable 2; one end of the cable 2 is connected to the circuit board assembly 12, and the other end is used to connect to the connector 3 to output the signal measured by the sensor probe through the connector 3.

[0027] The housing 11 is in the shape of an integrated cup, with a stud 111 at the front end, a hexagonal structure at the rear of the middle body 112 to facilitate the operation of tools such as a wrench, and a matching portion 113 in the shape of a ring at the rear end. The outer diameter of the matching portion 113 is slightly smaller than the middle body 112, and a step is formed with the middle body 112. A first accommodating cavity 114 for accommodating a circuit board assembly is provided inside the housing 11, and the first accommodating cavity 114 is provided with a mounting plane 1141. The mounting plane 1141 is provided with a plurality of grooves 1142 for filling the potting glue.

[0028] The circuit board assembly 12 includes a first circuit board 122, a second circuit board 123, and a third circuit board 124. The first circuit board 122 is mounted on the mounting plane 1141 and is disposed horizontally along the housing 11, and the second circuit board 123 is disposed longitudinally and is vertically clamped on the first circuit board 122. The third circuit board 124 is a flexible circuit board, and the second circuit board 123 is electrically connected to the first circuit board 122 through the third circuit board 124.

[0029] In this embodiment, the first circuit board 122 is circular, and its diameter is slightly smaller than the inner diameter of the first accommodating cavity 114. An accelerometer 121 with a sensitive direction of the Z axis is welded on the surface away from the installation plane. The accelerometer 121 is a core component. This embodiment adopts a torsion pendulum capacitive accelerometer, which is a capacitive accelerometer with a sensitive direction of the Z axis. It converts the vibration and impact of the sensor installation position into a capacitance change and outputs it in the form of voltage or current. A stress isolation cover 125 is provided on the accelerometer 121. The stress isolation cover 125 is a rectangular box with one end open, and can be made of rubber material. It is used to isolate the accelerometer 121 from the potting glue poured into the first accommodating cavity 114 to prevent the potting glue from being deformed by cold and hot temperatures and causing stress on the accelerometer 121, thereby stabilizing the zero-position output (stress on the accelerometer 121 will cause the zero-position output to drift, making the low-frequency or low-amplitude signal inaccurate).

[0030] In this embodiment, the second circuit board 123 is substantially rectangular, with a front end provided with an avoidance recess 1231 for avoiding the stress isolation cover 125 , and a rear end provided with a shoulder 1232 .

[0031] In this embodiment, the first circuit board 122 and the second circuit board 123 both adopt a soft-hard combination board design, that is, the third circuit board 124 is a soft board with M layers, and the first circuit board 122 and the second circuit board 123 have N layers, M≤N, and M layers among the N layers are flexible layers, so that the M flexible layers in the first circuit board 122 and the second circuit board 123 can be connected one-to-one with the corresponding layers of the third circuit board 124.

[0032] In practical applications, the third circuit board 124 will use a soft board with flex resistance, high temperature resistance and high insulation, and the thickness is generally less than 0.2 mm. It is usually set as one or two layers, and can usually be connected to the top, bottom or middle part of the first circuit board 122 and the second circuit board 123. For example, in one occasion, M=2, that is, the third circuit board 124 is a two-layer soft board, then the two layers of the third circuit board 124 can be connected to the first layer and the second layer of the first circuit board 122 and the second circuit board 123 respectively, and the first layer and the second layer of the first circuit board 122 and the second circuit board 123 are both flexible layers, and the first layer of the first circuit board 122 and the second circuit board 123 is the top layer. For another example, the two layers of the third circuit board 124 can be connected to the first to last layer and the second to last layer of the first circuit board 122 and the second circuit board 123 respectively. At this time, the first to last layer and the second to last layer of the first circuit board 122 and the second circuit board 123 are both flexible layers, and the first to last layer of the first circuit board 122 and the second circuit board 123 is the bottom layer. Of course, in addition to connecting to the top or bottom of the first circuit board 122 or the second circuit board 123, in other embodiments, appropriate M layers among the installed N layers can be selected as flexible layers as needed, and connected one-to-one with the corresponding layers of the third circuit board 124.

[0033] Therefore, since the first circuit board 122 and the second circuit board 123 adopt the above-mentioned soft-hard combination board design, the first circuit board 122 and the second circuit board 123 can be directly connected to the third circuit board 124 without setting up special interfaces, and the connection is not easily damaged due to bending, thereby ensuring reliability.

[0034] In this embodiment, the second circuit board 123 is vertically clamped on the first circuit board 122. Specifically, the first circuit board 122 is provided with a groove, including a first groove and a second groove; the second circuit board 123 has a first connecting end and a second connecting end, and the first connecting end is inserted into the first groove, and the second connecting end is inserted into the second groove; The first connection end has an L-shaped structure in the thickness direction for cooperating with the first groove, and the second connection end has an L-shaped structure in the thickness direction for cooperating with the second groove (such as Figure 8 As shown, the thickness of the portion of the first connecting end inserted into the first groove is narrower, and the thickness of the portion not inserted into the first groove is wider, forming an L-shaped structure, that is, a step structure); or, the first connecting end has an L-shaped structure for matching with the first groove in the length direction, and the second connecting end has an L-shaped structure for matching with the second groove in the length direction (such as Fig. 9 As shown, the length of the portion of the first connecting end inserted into the first groove is longer, and the length of the portion not inserted into the first groove is shorter, forming an L-shaped structure, that is, a step structure).

[0035] After assembly, the first circuit board 122 is closely attached to the mounting plane 1141, and the accelerometer 121 is welded on the surface of the first circuit board 122 away from the mounting plane 1141, so that the vibration impact signal generated by the device under test is transmitted to the accelerometer 121 through the housing, the mounting plane 1141, and the first circuit board 122. The transmission path of the vibration impact signal is as follows: Figure 4 As shown by the arrow, compared with the MEMS installed in-plane, the acceleration transmission distance is shorter and the signal transmission attenuation is smaller, so that the weak vibration impact response is better. And because the mounting plane 1141 is provided with a groove 1142, after filling with potting glue, the contact area between the first circuit board 122 and the sensor housing 11 can be increased, which is conducive to the transmission of weak signals.

[0036] In this embodiment, the mounting plane 1141 is located at one end of the first accommodating cavity 114 near the front end. The outer end surface of the housing 11 corresponding to the mounting plane 1141 includes an annular cone 115, so that the vibration impact signal generated by the device under test is transmitted to the mounting plane 1141 through the annular cone 115 on the housing 11, and the transmission path of the vibration impact signal is shorter. The angle of the annular cone 115 can be 90 degrees.

[0037] In this embodiment, the sensor probe further includes a stress isolation ring 127 , which may be made of elastic rubber material and is located on the shoulder of the second circuit board 123 .

[0038] In this embodiment, the sensor probe further includes a sealing locking member for sealing the interior of the sensor probe, the sealing locking member abuts against the shoulder of the second circuit board 123, and is used to cooperate with the second circuit board 123 to limit the second circuit board 123, and at the same time abut the first circuit board 121 against the mounting plane 1141. A stress isolation ring 127 is provided between the shoulder of the second circuit board 123 and the sealing locking member to absorb the deformation generated when the sealing locking member presses the circuit board, reduce the influence of the sealing locking member on the second circuit board 123 and further on the first circuit board 122, and avoid the deformation of the first circuit board 122 causing stress on the accelerometer 121 installed thereon, thereby stabilizing the zero position output.

[0039] The sealing and locking member can adopt a variety of different structures, which are not limited here.

[0040] In this embodiment, a structure of a sealing and locking member is provided. In this embodiment, the sealing and locking member includes a pressing sleeve 126 , a sealing ring 141 , and a pressing cover 142 .

[0041] The compression sleeve 126 is provided with a through hole, and the cable 2 passes through the through hole to connect with the second circuit board 123. The compression sleeve 126 is pressed against the second circuit board 123 to limit the second circuit board 123. The stress isolation ring 127 is located between the second circuit board 123 and the compression sleeve 126 to absorb the deformation caused by the compression of the compression sleeve 126, reduce the influence of the compression sleeve 126 on the second circuit board 123 and further on the first circuit board 122, and avoid the deformation of the first circuit board 122 causing the accelerometer 121 installed thereon to be subjected to stress, thereby stabilizing the zero-position output. Specifically, the compression sleeve 126 includes a circular flat-plate-shaped compression sleeve middle part 1261 and a cylindrical compression sleeve limiting part 1262. A through hole for the cable to pass through is provided in the middle of the compression sleeve middle part 1261, and the outer periphery cooperates with the inner wall of the outer shell 11. The sleeve limiting portion 1262 is formed by extending forward from the sleeve middle portion 1261 and abutting against the shoulder of the second circuit board 123 , and is used to cooperate with the second circuit board 123 to limit the second circuit board 123 , while pressing the first circuit board 121 against the mounting plane 1141 .

[0042] The sealing ring 141 is used to be fitted on the outer periphery of the cable 2, and the inner side of the front end of the gland 142 is fitted on the outer periphery of the sealing ring 141, so that the sealing ring 141 is pressed tightly against the outer periphery of the cable 2 and pressed against the middle part 1261 of the gland 126 (the sealing ring 141 can be a commonly used O-ring 141, which is small in size). The outer edge of the front end of the gland 142 is matched with the inner wall of the rear end of the housing 11. The rear end of the gland 142 is used to be fitted on the outer periphery of the cable 2, and an annular protrusion is provided on the outer periphery of the gland 142.

[0043] In this embodiment, the sealing and locking member further includes a threaded tube 151 (such as a nylon hose), a locking cap 152 , a sealing sleeve 153 , and a wire retaining spring 154 .

[0044] The threaded tube 151 is used to be fitted on the outer periphery of the gland 142 and the cable, and the inner groove of the threaded tube 151 matches the annular protrusion of the gland 142. The sealing sleeve 153 is located on the inner wall of the locking cap 152, and the front end of the locking cap 152 is fitted on the rear end of the outer shell 11 (matching part), and the middle position and the sealing sleeve 153 are fitted on the outer periphery of the threaded tube 151, and the sealing sleeve 153 is squeezed and embedded into the outer groove of the threaded tube 151. The lower part of the sealing sleeve 153 is tightly pressed against the rear end of the outer shell 11, and further, the inner side of its lower part is pressed against the gland 142, and the outer side of the lower part is connected to the inner wall of the outer shell 11. The wire protection spring 154 is located between the gland 142, the threaded tube 151 and the cable 2.

[0045] Figures 14 to 18 A schematic diagram of another embodiment of the sealing and locking member.

[0046] like Figures 14 to 18 As shown, in this embodiment, the sealing and locking member includes a gland 142', a cap 145, a pressure ring 146, and a sealing sleeve 147. In this embodiment, the gland 142', the cap 145, the pressure ring 146, and the sealing sleeve 147 are all provided with through holes for the cable 2' to pass through. The gland 142' includes a gland middle portion 1421, a gland limiting portion 1422 formed by extending forward from the gland middle portion 1421, and a cylindrical gland fixing portion 1423 formed by extending backward from the gland middle portion 1421, and an internal thread is provided on the inner side of the rear portion of the gland fixing portion 1423. The cable 2' passes through the through hole and is connected to the second circuit board 123'. The pressure cap 142' is pressed against the shoulder of the second circuit board 123' to limit the second circuit board 123' and press the first circuit board against the installation plane. The stress isolation ring 127' is located on the shoulder of the second circuit board and between the second circuit board 123' and the pressure cap 142' to absorb the deformation caused by the pressure cap 142'.

[0047] The sealing sleeve 147, the pressure ring 146, and the pressure cap 145 are sequentially sleeved on the outside of the cable 2' from the inside to the outside. The pressure cap 145 is provided with an external thread that matches the internal thread of the gland fixing part 1423. By screwing the pressure cap 145, the pressure cap 145 axially presses the pressure ring 146, and the pressure ring 146 then axially presses the sealing sleeve 147, so that the sealing sleeve 147 is pressed against the gland middle part 1421. The front end of the sealing sleeve 147 passes through the through hole on the gland middle part 1421 and enters the inner side of the gland limiting part 1422. The sealing sleeve 147 is relatively long, which not only makes the sealing performance better, but also plays the role of isolating the electrical creepage distance between the cable core wire and the shell.

[0048] The sealing and locking member further comprises a rubber protective sleeve 155 , a cable protective sleeve 156 , and a nylon hose 157 for protecting the cable. The front end of the rubber protective sleeve 155 covers the gland fixing portion 1423 , and the cable protective sleeve 156 is installed between the rubber protective sleeve 155 and the nylon hose 157 .

[0049] The assembly process of the sensor probe of this embodiment includes: 1. Solder the accelerometer and the temperature sensitive device on the first circuit board; 2. Cover the accelerometer with a stress isolation cover; then assemble the first circuit board and the second circuit board together through their own grooves and connection ends, so that the accelerometer, circuit board assembly, etc. form an independent core assembly; 3. Weld the cable to the core components; 4. Fill a certain amount of potting glue into the sensor housing to ensure that the mounting platforms of the second accommodating cavity and the first accommodating cavity are filled with potting glue; place the core component into the sensor housing; and fill a certain amount of potting glue into the sensor housing again to the specified position, generally higher than the accelerometer and lower than the bottom of the compression sleeve.

[0050] 5. Then put the stress isolation ring on the second circuit board, put the sealing assembly on the cable, press the second circuit board tightly, and complete the internal sealing of the sensor housing; 6. Complete the assembly and calibration of the sensor probe.

[0051] In this embodiment, the sampling signal sent by the accelerometer 121 needs to be transmitted to the conditioning circuit of the second circuit board 123, and the conditioning circuit processes the signal, and the processed signal is used as the acceleration detection signal obtained by the sensor. The specific circuit structure of the conditioning circuit can be set according to actual needs. For example, the conditioning circuit can usually perform voltage amplification, current-voltage conversion and other operations.

[0052] In a specific embodiment of the present invention, please refer to Fig.11 , is a schematic diagram of a structure of a conditioning circuit in a specific implementation manner, and the conditioning circuit may include: A filter circuit 301 connected to the accelerometer 121, used for filtering the sampling signal output by the accelerometer 121; The signal conversion circuit 302 connected to the filter circuit 301 is used to amplify the output of the filter circuit, or to amplify and convert the output of the filter circuit 301 into voltage and current; An interface protection circuit 303 is connected to the signal conversion circuit 302 for anti-interference, and the output of the interface protection circuit 303 is used as the acceleration detection signal obtained after the output processing of the conditioning circuit.

[0053] This implementation takes into account that the accelerometer 121 has a resonance peak output, and the use bandwidth of the traditional accelerometer 121 is 1 / 3 of the resonance frequency. In order to balance sensitivity and noise, the natural frequency design of some accelerometers 121 will be less than 30kHz, which cannot meet the demand for a use bandwidth of more than 10kHz. In this implementation, a filter circuit 301 is connected to the output end of the accelerometer 121 for filtering, which is usually a first-order RC low-pass filter circuit, which can not only filter out high-frequency noise, but also suppress the resonance peak, thereby expanding the use bandwidth of the accelerometer 121.

[0054] See also Fig.12 , is a schematic diagram of the structure of a conditioning circuit in another specific implementation. Fig.13 In the implementation manner, the output end of the accelerometer 121 is Vmems, and the filter circuit 301 specifically adopts a first-order RC low-pass filter circuit, and the resistor and capacitor in the first-order RC low-pass filter circuit are respectively recorded as R0 and C0. In addition, in some implementation manners, the resistor in the first-order RC low-pass filter circuit can also be integrated inside the accelerometer 121.

[0055] The signal conversion circuit 302 can amplify the output of the filter circuit 301, or can amplify the output of the filter circuit 301 and convert the voltage into current, that is, it is designed as a current output type sensor, which can be designed according to actual needs, for example Fig.12 In the example, the signal conversion circuit 302 is composed of an operational amplifier and two resistors, which can amplify the output of the filter circuit 301 and is a voltage output type sensor. Fig.13 In the example, the signal conversion circuit 302 is composed of an operational amplifier, a resistor and a switch tube, which can convert the voltage signal into a current signal and amplify the output of the filter circuit 301.

[0056] The interface protection circuit 303 has various structures, for example, Fig.13 The output of the interface protection circuit 303 is realized by using a transient voltage suppression diode RV1 in the embodiment of the present invention, which has a simple structure and low cost. Fig.13 In addition, Fig.12 and Fig.13 In both figures, a power supply circuit is shown above the signal conversion circuit 302, which can realize circuit power supply. In other specific implementations, the specific structure of the power supply circuit can be set as needed.

[0057] The above description of the disclosed embodiments enables one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be apparent to one skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but rather to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A sensor probe whose sensitive axis is the Z axis, characterized in that: It includes a shell, a circuit board assembly, and a cable. The shell is provided with a first accommodating cavity for accommodating the circuit board assembly, and a mounting plane is provided at the front end of the first accommodating cavity; the circuit board assembly includes a first circuit board, a second circuit board, and a third circuit board. The first circuit board is tightly attached to the mounting plane, and an accelerometer with a sensitive direction of the Z axis is welded on the surface away from the mounting plane. The second circuit board is vertically clamped on the first circuit board, and the first circuit board and the second circuit board are connected through a third circuit board. The third circuit board is a flexible circuit board.

2. The sensor probe whose sensitive axis is the Z axis as claimed in claim 1, characterized in that: The mounting plane is arranged transversely along the shell and is located at one end of the first accommodating cavity close to the front end. The outer end surface of the shell corresponding to the mounting plane includes an annular cone surface, so that the vibration impact signal generated by the device under test is transmitted to the mounting plane through the annular cone surface on the shell.

3. The sensor probe whose sensitive axis is the Z axis according to claim 1, characterized in that: It also includes a temperature sensitive device. The front end of the shell is provided with a stud for being installed on the device under test through the stud. A second accommodating cavity connected to the first accommodating cavity is provided inside the stud. The temperature sensitive device is accommodated in the second accommodating cavity and is electrically connected to the first circuit board.

4. The sensor probe with the sensitive axis being the Z axis as claimed in claim 1, characterized in that: The first circuit board is circular, and its diameter is slightly smaller than the inner diameter of the first accommodating cavity.

5. The sensor probe whose sensitive axis is the Z axis as claimed in claim 1, characterized in that: The installation plane is provided with a plurality of grooves for filling the potting glue.

6. The sensor probe with the sensitive axis being the Z axis as claimed in claim 1, characterized in that: It also includes a stress isolation cover which is arranged on the accelerometer whose sensitive direction is the Z axis and is used to isolate the accelerometer whose sensitive direction is the Z axis from the potting glue filled in the first accommodating cavity.

7. The sensor probe with the sensitive axis being the Z axis as claimed in claim 1, characterized in that: The second circuit board is vertically clamped on the first circuit board as follows: the first circuit board is provided with a groove, the second circuit board is fixed on the first circuit board through the groove, the groove provided on the first circuit board includes a first groove and a second groove; the second circuit board has a first connecting end and a second connecting end, the first connecting end is inserted into the first groove, and the second connecting end is inserted into the second groove; The first connecting end has an L-shaped structure in the thickness direction for cooperating with the first groove, and the second connecting end has an L-shaped structure in the thickness direction for cooperating with the second groove; or; The first connecting end has an L-shaped structure in the length direction for cooperating with the first groove, and the second connecting end has an L-shaped structure in the length direction for cooperating with the second groove.

8. The sensor probe with the sensitive axis being the Z axis as claimed in claim 1, characterized in that: The circuit board assembly is provided with a conditioning circuit, and the conditioning circuit comprises: A filter circuit connected to the accelerometer, used for filtering the sampling signal output by the accelerometer; A signal conversion circuit connected to the filter circuit, used to amplify the output of the filter circuit, or to amplify the output of the filter circuit and convert it into voltage or current; An interface protection circuit is connected to the signal conversion circuit and is used for anti-interference, and the output of the interface protection circuit is used as the output of the conditioning circuit to output the detection signal obtained after processing.

9. The sensor probe with the sensitive axis being the Z axis as claimed in claim 8, characterized in that: The conditioning circuit is arranged on the second circuit board.

10. The sensor probe with the sensitive axis being the Z axis as claimed in claim 9, characterized in that: The first circuit board and the second circuit board each have N layers, and M layers among the N layers are flexible layers, and the M flexible layers are connected to the corresponding layers of the third circuit board in a one-to-one correspondence; wherein M and N are both positive integers, M represents the number of layers of the third circuit board, N represents the number of layers of the first circuit board and the second circuit board, and M≤N; the second circuit board is used to receive the sampling signal of the accelerometer through the first circuit board and the third circuit board, process the sampling signal through the conditioning circuit, and output the detection signal obtained after processing.

11. The sensor probe with the sensitive axis being the Z axis according to claim 6, characterized in that: The second circuit board is rectangular, and a relief recess for avoiding the stress isolation cover is provided at the front end.

12. The sensor probe with the sensitive axis being the Z axis as claimed in claim 8, characterized in that: It also includes a stress isolation ring. A shoulder is provided at the rear end of the second circuit board, and the stress isolation ring is located on the shoulder.

13. The sensor probe with the sensitive axis being the Z axis as claimed in claim 12, characterized in that: It also includes a sealing locking piece, which is provided with a through hole. The cable passes through the through hole to be connected to the second circuit board. The sealing locking piece is pressed against the shoulder of the second circuit board to limit the position of the second circuit board and press the first circuit board against the mounting plane. The stress isolation ring is located between the second circuit board and the sealing locking piece.

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