Sensor with Z-axis sensitive axis

Abstract

The utility model discloses a sensor with a Z-axis sensitive axis, which comprises a shell, a circuit board assembly, a cable, a connector and a sealing locking piece, and is characterized in that the shell is internally provided with a first accommodating cavity for accommodating the circuit board assembly, and the front end of the first accommodating cavity is provided with a mounting plane; 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. The first circuit board is connected with the second circuit board through a third circuit board; the sealing locking piece abuts against the shoulder portion of the second circuit board so as to limit the second circuit board and enable the first circuit board to abut against the installation plane. According to the sensor with the sensitive axis being the Z axis, an accelerometer with the sensitive direction being the Z axis can receive vibration and impact signals more easily, and the test precision is remarkably improved.

Description

Technical Field

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

[0002] In the field of vibration and shock signal detection and fault diagnosis, comb-tooth MEMS (Micro-electromechanical Systems) accelerometers are currently widely used as the core sensor components. These accelerometers, with their sensitive axis oriented in-plane and along the Z-axis, are mounted horizontally on a PCB and then mounted inside the sensor housing along with the PCB. This mounting method complicates the signal transmission path. Furthermore, the sensor structure imposes packaging stress on accelerometers with a Z-axis sensitivity, resulting in low accuracy in detecting low-frequency, weak vibration and shock signals. Compared to accelerometers with an in-plane sensitive axis, accelerometers with an out-of-plane sensitive axis, also known as Z-axis sensitive accelerometers, offer superior performance. The mounting requirements for these MEMS accelerometers differ from those for in-plane accelerometers. In actual engineering applications, MEMS accelerometers are usually used in conjunction with peripheral circuits. These circuits are typically printed on a PCB (Printed Circuit Board), and the accelerometer is soldered to the PCB. However, these structures are usually large, resulting in a larger sensor overall and failing to meet the small size requirements of some applications.

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

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

[0005] The technical solutions provided by this utility model are as follows:

[0006] A sensor with a sensitive axis of Z axis includes a shell, a circuit board assembly, a cable, a connector, and a sealing and locking piece. 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; one end of the cable is connected to the circuit board assembly, and the other end is connected to the connector; 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 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; the sealing and locking piece is provided with a through hole, and the cable passes through the through hole to be connected to the second circuit board. The sealing and locking piece is pressed against the shoulder of the second circuit board to limit the second circuit board and press the first circuit board against the mounting plane.

[0007] 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 face of the shell corresponding to the mounting plane includes an annular conical surface, so that the vibration impact signal generated by the device under test is transmitted to the mounting plane through the annular conical surface on the shell.

[0008] 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.

[0009] Preferably, the first circuit board is circular, and its diameter is slightly smaller than the inner diameter of the first accommodating cavity.

[0010] Preferably, a plurality of grooves for filling with potting glue are provided on the mounting plane.

[0011] Preferably, it further comprises a stress isolation cover provided on the accelerometer having a sensitive direction of the Z axis for isolating the accelerometer having a sensitive direction of the Z axis from the potting compound filled in the first accommodation cavity.

[0012] Preferably, the second circuit board is rectangular, and a relief recess is provided at the front end for evading the stress isolation cover.

[0013] Preferably, the second circuit board is vertically clamped to the first circuit board as follows: the first circuit board is provided with a groove, the second circuit board is fixed to 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;

[0014] 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;

[0015] or;

[0016] 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.

[0017] 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 one-to-one with the corresponding layers of the third circuit board; 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 first flexible circuit board, process the sampling signal through the conditioning circuit, and output the acceleration detection signal obtained after processing; the conditioning circuit is located on the circuit board assembly.

[0018] Preferably, a stress isolation ring is further included. A shoulder is provided at the rear end of the second circuit board. The stress isolation ring is installed on the shoulder and is located between the second circuit board and the sealing and locking member.

[0019] Preferably, the sealing and locking part includes a pressing sleeve, a sealing ring, and a pressing cover; the pressing sleeve includes a circular flat-plate pressing sleeve middle part and a cylindrical limiting part; a through hole is provided in the middle of the pressing sleeve middle part for the cable to pass through, and the outer periphery cooperates with the inner wall of the outer shell, and the pressing sleeve limiting part is formed by the middle part of the pressing sleeve extending forward and abutting against the shoulder of the second circuit board; the sealing ring is sleeved on the outer periphery of the cable, and the inner side of the front end of the pressing cover is sleeved on the outer periphery of the sealing ring to press the sealing ring against the outer periphery of the cable and against the pressing sleeve middle part of the pressing sleeve, and the rear end of the pressing cover is sleeved on the outer periphery of the cable.

[0020] Preferably, an annular protrusion is provided on the outer periphery of the gland, and the sealing locking component also includes a threaded tube, a locking cap 152, a sealing sleeve, and a wire protection spring; the threaded tube is sleeved on the outer periphery of the gland and the cable, and the inner groove of the threaded tube cooperates with the annular protrusion of the gland; the sealing sleeve is located on the inner wall of the locking cap, the front end of the locking cap is sleeved on the rear end outside of the outer shell, and the middle position and the sealing sleeve are sleeved on the outer periphery of the threaded tube, and the sealing sleeve is squeezed and embedded into the outer groove of the threaded tube; the inner side of the lower part of the sealing sleeve is pressed against the gland, and the outer side of the lower part is connected to the inner wall of the outer shell; the wire protection spring is located between the gland, the threaded tube and the cable.

[0021] Preferably, the sealing and locking component includes a gland, a pressure cap, a pressure ring, and a sealing sleeve; the gland includes a gland middle part, a gland limiting part formed by extending forward from the gland middle part, and a cylindrical gland fixing part formed by extending backward from the gland middle part, the gland limiting part is tightly abutted against the shoulder of the second circuit board, and an internal thread is provided on the inner side of the rear part of the gland fixing part; the sealing sleeve, pressure ring, and gland cap are sequentially sleeved on the outside of the cable from the inside to the outside; the pressure cap is provided with an external thread that matches the internal thread of the gland fixing part, and by screwing in the pressure cap, the pressure cap is axially pressed against the pressure ring, and the pressure ring then axially presses the sealing sleeve so that the sealing sleeve is pressed against the middle part of the gland; the front end of the sealing sleeve passes through the through hole on the middle part of the gland and enters the inner side of the gland limiting part.

[0022] Preferably, the sealing and locking member further comprises a rubber protective sleeve, a cable sheath, and a nylon hose. The front end of the rubber protective sleeve covers the gland fixing portion, and the cable sheath is installed between the rubber protective sleeve and the nylon hose.

[0023] Compared to the prior art, the present invention utilizes a sensor with a Z-axis sensitive axis. By soldering an accelerometer with a Z-axis sensitive direction to the surface of a first circuit board, and with the first circuit board in close contact with the mounting plane of the housing, the contact area between the housing and the accelerometer with a Z-axis sensitive direction is increased, making it easier for the accelerometer with a Z-axis sensitive direction to receive vibration and impact signals, significantly improving test accuracy. Furthermore, a second circuit board is vertically clipped onto the first circuit board, and the first and second circuit boards are connected via a flexible circuit board, resulting in a compact structure and minimal space. This miniaturizes the sensor and meets the installation requirements for monitoring locations such as axle boxes and motors on rotating components of locomotive and subway vehicle running gear in rail transit. Furthermore, an annular conical surface is provided on the outer end face of the housing corresponding to the mounting plane, allowing vibration and impact signals generated by the device under test to be transmitted through the annular conical surface on the housing to the mounting plane. This simplifies the signal transmission path and makes it easier for the accelerometer with a Z-axis sensitive direction to receive vibration and impact signals, significantly improving 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

[0024] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments recorded in this application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0025] Figure 1A three-dimensional combination diagram of a sensor according to an embodiment of the present utility model;

[0026] Figure 2 for Figure 1 An exploded perspective view of the sensor shown;

[0027] Figure 3 for Figure 1 An exploded perspective view of the front end portion of the sensor shown;

[0028] Figure 4 for Figure 3 A longitudinal sectional view of the front end portion of the sensor shown;

[0029] Figure 5 for Figure 3 A longitudinal sectional view of the front end portion of the sensor in another direction;

[0030] Figure 6 for Figure 1 A longitudinal section view of the housing of the sensor shown;

[0031] Figure 7 for Figure 6 a cross-sectional view of the housing probe shown;

[0032] Figure 8 for Figure 1 A three-dimensional diagram of the circuit board assembly and accelerometer in the sensor shown;

[0033] Figure 9 for Figure 1 A perspective view of the stress isolation shield in the illustrated sensor;

[0034] Figure 10 for Figure 1 A three-dimensional combined view of another specific embodiment of the circuit board assembly and the accelerometer in the sensor;

[0035] Figure 11 for Figure 1 A schematic diagram of the structure of the conditioning circuit in the sensor shown;

[0036] Figure 12 for Figure 1 A schematic structural diagram of another specific embodiment of a conditioning circuit in the sensor shown;

[0037] Figure 13 for Figure 1 A schematic structural diagram of another specific embodiment of the conditioning circuit in the sensor shown;

[0038] Figure 14 A three-dimensional assembly diagram of a sensor according to another embodiment of the present invention;

[0039] Figure 15 for Figure 14An exploded perspective view of the sensor shown;

[0040] Figure 16 for Figure 14 An exploded perspective view of the front end portion of the sensor shown;

[0041] Figure 17 for Figure 16 A longitudinal sectional view of the front end portion of the sensor shown;

[0042] Figure 18 for Figure 16 A longitudinal sectional view of the front end of the sensor in another direction is shown. DETAILED DESCRIPTION

[0043] In order to help those skilled in the art 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 embodiments described are only part of the embodiments of this application, not all of the embodiments. Based on the embodiments in this application, all other embodiments obtained by those skilled in the art without making any creative efforts shall fall within the scope of protection of this application.

[0044] 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.

[0045] 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 accompanying drawings, and are only for the convenience of describing this 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 cannot be understood as a limitation on this application.

[0046] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be understood to indicate or imply relative importance or implicitly specify the number of technical features indicated. Thus, a feature specified as "first" or "second" may explicitly or implicitly include one or more of such features. Throughout the description of this application, "plurality" or "several" means two or more, unless otherwise specifically defined.

[0047] 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 efficacy and purpose that can be achieved by this application.

[0048] like Figures 1 to 13 As shown, an embodiment of the present invention provides a sensor whose sensitive axis is the Z axis, including a housing 11, a circuit board assembly, a cable 2, and a connector 3. One end of the cable 2 is connected to the circuit board assembly 12, and the other end is used for the connector 3 to output the signal measured by the sensor through the connector 3.

[0049] The housing 11 is a one-piece, cup-shaped structure with a stud 111 at the front. A hexagonal structure is located at the rear of the center body 112 to facilitate access with tools such as wrenches. A circular mating portion 113 is located at the rear end. The outer diameter of the mating portion 113 is slightly smaller than that of the center body 112, forming a step with the center body 112. A first accommodating cavity 114 for accommodating the circuit board assembly is located within the housing 111. This first accommodating cavity 114 has a mounting surface 1141. This mounting surface 1141 is provided with multiple grooves 1142 for filling with potting compound.

[0050] 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 arranged horizontally along the housing 11. The second circuit board 123 is arranged vertically and snaps onto 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.

[0051] In this embodiment, the first circuit board 122 is circular, with a diameter slightly smaller than the inner diameter of the first accommodating cavity 114. An accelerometer 121 with a sensitivity direction of the Z axis is welded on the surface away from the mounting plane. The accelerometer 121 is a core component. This embodiment uses a torsion pendulum capacitive accelerometer, which is a capacitive accelerometer with a sensitivity direction of the Z axis. It converts vibration and impact at the sensor installation location into capacitance changes and outputs them 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. It is used to isolate the accelerometer 121 from the potting compound injected into the first accommodating cavity 114 to prevent the potting compound from deforming due to hot and cold temperatures, which would cause stress on the accelerometer 121, thereby stabilizing the zero-position output (stress on the accelerometer 121 would cause the zero-position output to drift, resulting in inaccurate low-frequency or low-amplitude signals).

[0052] 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 .

[0053] In this embodiment, the first circuit board 122 and the second circuit board 123 both adopt a soft-rigid 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.

[0054] In practical applications, the third circuit board 124 will be a flexible board with flexural resistance, high temperature resistance, and high insulation properties. Its thickness is generally less than 0.2 mm, and it is typically configured as one or two layers. It can typically be connected to the top, bottom, or middle portion of the first circuit board 122 and the second circuit board 123. For example, in one embodiment, M = 2, meaning the third circuit board 124 is a two-layer flexible board. In this case, the two layers of the third circuit board 124 can be connected to the first and second layers of the first circuit board 122 and the second circuit board 123, respectively. The first and second layers of the first circuit board 122 and the second circuit board 123 are both flexible layers, with the first layer of the first circuit board 122 and the second circuit board 123 being 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. In this case, 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, with the first-to-last layer of the first circuit board 122 and the second circuit board 123 being 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.

[0055] 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 by bending, thereby ensuring reliability.

[0056] 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;

[0057] 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 (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 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 (as shown in FIG. Figure 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).

[0058] After assembly, the first circuit board 122 is tightly attached to the mounting plane 1141, and the accelerometer 121 is soldered on the surface of the first circuit board 122 away from the mounting plane 1141, so that the vibration shock 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 vibration shock signal transmission path is as follows: Figure 4 As shown by the arrows, compared to in-plane MEMS mounting, the acceleration transmission distance is shorter and the signal transmission attenuation is reduced, resulting in better response to weak vibration shocks. Furthermore, because the mounting surface 1141 is provided with grooves 1142, after filling with potting compound, the contact area between the first circuit board 122 and the sensor housing 11 is increased, facilitating the transmission of weak signals.

[0059] In this embodiment, mounting plane 1141 is located at the front end of first accommodating cavity 114. The outer end surface of housing 11, corresponding to mounting plane 1141, includes an annular conical surface 115. This allows vibration and shock signals generated by the device under test to be transmitted through annular conical surface 115 on housing 11 to mounting plane 1141, shortening the transmission path of the vibration and shock signals. The angle of annular conical surface 115 can be 90 degrees.

[0060] In this embodiment, the sensor 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 .

[0061] In this embodiment, the sensor also includes a sealing and locking member for sealing the interior of the sensor. The sealing and locking member abuts the shoulder of the second circuit board 123, cooperating with the second circuit board 123 to limit the position of the second circuit board 123 while simultaneously pressing the first circuit board 121 against the mounting surface 1141. A stress isolation ring 127 is provided between the shoulder of the second circuit board 123 and the sealing and locking member to absorb deformation caused by the sealing and locking member pressing against the circuit board. This reduces the impact of the sealing and locking member on the second circuit board 123 and further on the first circuit board 122, preventing deformation of the first circuit board 122 from causing stress on the accelerometer 121 mounted thereon, thereby stabilizing the zero-position output.

[0062] The sealing and locking member can adopt a variety of different structures, which are not limited here.

[0063] 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 .

[0064] The compression sleeve 126 is provided with a through hole, and the cable 2 passes through the through hole and is connected to 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 impact 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 also 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 is matched with the inner wall of the outer shell 11. The pressing sleeve limiting portion 1262 is formed by extending forward from the pressing 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 and at the same time press the first circuit board 121 against the mounting plane 1141 .

[0065] The sealing ring 141 is designed to fit over the outer circumference of the cable 2. The inner front end of the gland 142 fits over the outer circumference of the sealing ring 141, pressing the sealing ring 141 against the outer circumference of the cable 2 and against the middle portion 1261 of the gland 126. (The sealing ring 141 can be a conventional O-ring 141, which is compact.) The outer edge of the front end of the gland 142 mates with the inner wall of the rear end of the housing 11. The rear end of the gland 142 fits over the outer circumference of the cable 2 and is provided with an annular protrusion on its outer circumference.

[0066] 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 .

[0067] The threaded tube 151 is designed to fit over the gland 142 and the outer circumference of the cable, with the inner groove of the threaded tube 151 mating with the annular protrusion of the gland 142. A sealing sleeve 153 is located on the inner wall of the locking cap 152. The front end of the locking cap 152 fits over the rear end of the housing 11 (the mating portion), while the middle portion and the sealing sleeve 153 fit over the outer circumference of the threaded tube 151, squeezing the sealing sleeve 153 into the outer groove of the threaded tube 151. The lower portion of the sealing sleeve 153 abuts the rear end of the housing 11. Furthermore, the inner side of its lower portion abuts against the gland 142, while the outer side of its lower portion contacts the inner wall of the housing 11. A wire retaining spring 154 is located between the gland 142, the threaded tube 151, and the cable 2.

[0068] Figures 14 to 18 Schematic diagram of another embodiment of the sealing and locking member.

[0069] like Figures 14 to 18 As shown, in this embodiment, the sealing and locking member includes a gland 142', a pressure cap 145, a pressure ring 146, and a sealing sleeve 147. In this embodiment, the gland 142', the pressure cap 145, the pressure ring 146, and the sealing sleeve 147 are all provided with a through hole 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. The inner side of the rear portion of the gland fixing portion 1423 is provided with an internal thread. The cable 2' passes through the through hole and is connected to the second circuit board 123'. The pressure cover limiting portion 1422 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 mounting 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 cover 142' to absorb the deformation caused by the pressure of the pressure cover 142'.

[0070] The sealing sleeve 147, pressure ring 146, and pressure cap 145 are sequentially sleeved onto the outside of the cable 2' from the inside out. Pressure cap 145 has external threads that mate with the internal threads of the gland fixing portion 1423. By screwing pressure cap 145 into place, it axially compresses pressure ring 146, which in turn axially compresses sealing sleeve 147, forcing it tightly against the gland intermediate portion 1421. The front end of sealing sleeve 147 passes through a through-hole in the gland intermediate portion 1421 and into the interior of the gland limiting portion 1422. The length of sealing sleeve 147 not only improves sealing performance but also serves to isolate the electrical creepage distance between the cable core and the outer casing.

[0071] The sealing and locking member further includes a rubber protective sleeve 155 , a cable sheath 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 sheath 156 is installed between the rubber protective sleeve 155 and the nylon hose 157 .

[0072] The assembly process of the sensor in this embodiment includes:

[0073] 1. Solder the accelerometer and temperature sensitive device to the first circuit board;

[0074] 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. In this way, the accelerometer, circuit board assembly, etc. form an independent core component;

[0075] 3. Solder the cables to the core components;

[0076] 4. Fill the sensor housing with a certain amount of potting compound to ensure that the mounting platform of the second accommodating cavity and the first accommodating cavity are fully filled with potting compound; place the core component into the sensor housing; and again fill the sensor housing with a certain amount of potting compound to the designated position, generally above the accelerometer and below the bottom of the compression sleeve.

[0077] 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;

[0078] 6. Complete the assembly and calibration of the sensor.

[0079] In this embodiment, the sampling signal sent by the accelerometer 121 is transmitted to the conditioning circuit on the second circuit board 123 for processing. The processed signal serves 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 generally perform operations such as voltage amplification and current-to-voltage conversion.

[0080] In a specific embodiment of the present invention, please refer to Figure 11 , is a structural diagram of a conditioning circuit in a specific implementation manner, the conditioning circuit may include:

[0081] A filter circuit 301 connected to the accelerometer 121, for filtering the sampling signal output by the accelerometer 121;

[0082] 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;

[0083] 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 of the conditioning circuit is processed.

[0084] This implementation takes into account that accelerometer 121 has a resonant peak output. Conventional accelerometers 121 have a usable bandwidth of 1 / 3 the resonant frequency. To balance sensitivity and noise, some accelerometers 121 have a natural frequency design less than 30 kHz, failing to meet the requirement for a usable bandwidth of at least 10 kHz. In this implementation, a filter circuit 301 is connected to the output of accelerometer 121 for filtering. This filter circuit, typically a first-order RC low-pass filter circuit, not only filters out high-frequency noise but also suppresses the resonant peak, thereby extending the usable bandwidth of accelerometer 121.

[0085] See Figure 12 , is a structural diagram of a conditioning circuit in another specific embodiment. Figure 13 In the embodiment, the output terminal of accelerometer 121 is Vmems, and filter circuit 301 specifically implements a first-order RC low-pass filter circuit. The resistor and capacitor in the first-order RC low-pass filter circuit are denoted as R0 and C0, respectively. In some embodiments, the resistor in the first-order RC low-pass filter circuit can also be integrated into accelerometer 121.

[0086] The signal conversion circuit 302 can amplify the output of the filter circuit 301, or 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 Figure 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. Figure 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.

[0087] There are many structures of the interface protection circuit 303, for example, Figure 13 The output of the interface protection circuit 303 is realized by using a transient voltage suppression diode RV1 and other methods, which has a simple structure and low cost. Figure 13 In addition, Figure 12 and Figure 13 In each of the figures, a power supply circuit is shown above the signal conversion circuit 302 to realize circuit power supply. In other specific implementations, the specific structure of the power supply circuit can be set as needed.

[0088] The above description of the disclosed embodiments will enable one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be readily 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 is not limited to the embodiments shown herein, but is intended to conform to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A sensor whose sensitive axis is the Z axis, characterized in that: It includes a shell, a circuit board assembly, a cable, a connector, and a sealing and locking piece. The shell is provided with a first accommodating cavity for accommodating the circuit board assembly, and the front end of the first accommodating cavity is provided with a mounting plane; one end of the cable is connected to the circuit board assembly, and the other end is connected to the connector; 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 the third circuit board. The third circuit board is a flexible circuit board; the sealing and locking piece is provided with a through hole, and the cable passes through the through hole to be connected to the second circuit board. The sealing and locking piece is pressed against the shoulder of the second circuit board to limit the second circuit board and press the first circuit board against the mounting plane.

2. The sensor with the sensitive axis being the Z axis according to claim 1, characterized in that: 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 conical surface, so that the vibration impact signal generated by the device under test is transmitted to the mounting plane through the annular conical surface on the shell.

3. The sensor with the sensitive axis being the Z axis according to claim 1, characterized in that: It also includes a temperature sensitive device. A stud is provided at the front end of the shell 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 with the sensitive axis being the Z axis according to claim 1, wherein: It also includes a stress isolation cover which is arranged on the accelerometer with the sensitive direction of the Z axis and is used to isolate the accelerometer with the sensitive direction of the Z axis from the potting glue filled in the first accommodating cavity.

5. The sensor with the sensitive axis being the Z axis according to claim 1, characterized in that: The second circuit board is vertically clamped to the first circuit board as follows: the first circuit board is provided with a groove, the second circuit board is fixed to 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.

6. The sensor with the sensitive axis being the Z axis according to claim 1, characterized in that: The first circuit board and the second circuit board each have N layers, and M of the N layers are flexible layers, and the M flexible layers are connected one-to-one with the corresponding layers of the third circuit board; 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 first flexible circuit board, process the sampling signal through a conditioning circuit, and output the acceleration detection signal obtained after processing; the conditioning circuit is located on the circuit board assembly.

7. The sensor with the sensitive axis being the Z axis according to claim 1, characterized in that: It also includes a stress isolation ring located between the second circuit board and the sealing and locking member.

8. The sensor with the sensitive axis being the Z axis according to claim 7, characterized in that: A shoulder is provided at the rear end of the second circuit board, and the stress isolation ring is installed on the shoulder.

9. The sensor with the sensitive axis being the Z axis according to claim 8, characterized in that: The sealing and locking part includes a pressing sleeve, a sealing ring, and a pressing cover; the pressing sleeve includes a circular flat-plate pressing sleeve middle part and a cylindrical limiting part; a through hole is provided in the middle of the pressing sleeve middle part for the cable to pass through, and the outer periphery cooperates with the inner wall of the outer shell, and the pressing sleeve limiting part is formed by the middle part of the pressing sleeve extending forward and abutting against the shoulder of the second circuit board; the sealing ring is sleeved on the outer periphery of the cable, and the inner side of the front end of the pressing cover is sleeved on the outer periphery of the sealing ring to press the sealing ring against the outer periphery of the cable and against the pressing sleeve middle part of the pressing sleeve, and the rear end of the pressing cover is sleeved on the outer periphery of the cable.

10. The sensor with the sensitive axis being the Z axis according to claim 9, characterized in that: An annular protrusion is provided on the outer periphery of the gland, and the sealing locking part also includes a threaded tube, a locking cap 152, a sealing sleeve, and a wire protection spring; the threaded tube is sleeved on the outer periphery of the gland and the cable, and the inner groove of the threaded tube cooperates with the annular protrusion of the gland; the sealing sleeve is located on the inner wall of the locking cap, the front end of the locking cap is sleeved on the rear end outside of the shell, and the middle position and the sealing sleeve are sleeved on the outer periphery of the threaded tube, and the sealing sleeve is squeezed and embedded into the outer groove of the threaded tube; the inner side of the lower part of the sealing sleeve is pressed against the gland, and the outer side of the lower part is connected to the inner wall of the shell; the wire protection spring is located between the gland, the threaded tube and the cable.

11. The sensor with the sensitive axis being the Z axis according to claim 8, characterized in that: The sealing locking part includes a gland, a pressure cap, a pressure ring, and a sealing sleeve; the gland includes a gland middle part, a gland limiting part formed by extending forward from the gland middle part, and a cylindrical gland fixing part formed by extending backward from the gland middle part, the gland limiting part is tightly abutted against the shoulder of the second circuit board, and an internal thread is provided on the inner side of the rear part of the gland fixing part; the sealing sleeve, pressure ring, and gland cap are sequentially sleeved on the outside of the cable from the inside to the outside; the gland is provided with an external thread that matches the internal thread of the gland fixing part, and by screwing in the gland, the gland is axially pressed against the pressure ring, and the pressure ring then axially presses the sealing sleeve so that the sealing sleeve is pressed against the middle part of the gland; the front end of the sealing sleeve passes through the through hole on the middle part of the gland and enters the inner side of the gland limiting part.

12. The sensor with the sensitive axis being the Z axis according to claim 11, characterized in that: The sealing and locking component also includes a rubber protective sleeve, a cable sheath, and a nylon hose. The front end of the rubber protective sleeve covers the gland fixing portion, and the cable sheath is installed between the rubber protective sleeve and the nylon hose.

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