Low-power-consumption winch sensor based on tunneling magnetoresistance effect

Abstract

The invention discloses a low-power-consumption winch sensor based on a tunneling magnetoresistance effect. The low-power-consumption winch sensor comprises a measurement module, a signal conversion unit, a shell, a mandrel, a magnetic rotary disc and a detection assembly. The magnetic turntable and the mandrel are connected and rotate synchronously, the detection assembly comprises a TMR sensing element and N magnets, and the magnetic turntable is provided with mounting blind holes for embedding the magnets; the TMR sensing element is arranged on the shell and comprises a mounting plate and two sensing units, the magnetic domain directions of the two sensing units are perpendicular to the rotation axis, magnetic resistance signals of the two sensing units are converted through the signal conversion unit and input into the measuring module, the horizontal distance between the centers of the two sensing units and the magnet and the rotation axis is R, and the center distance L of the two sensing units is smaller than R * sin (180 degrees / N); the sensor is based on the TMR tunneling magnetoresistance effect, is high in detection sensitivity and low in energy consumption, outputs square wave signals with phase differences, can be used for a measurement module to accurately analyze and calculate the rotating speed and the rotating direction of a winch roller, is simple in overall structure, small in radial size and easy to install, and the installation precision is controlled.

Description

Technical Field

[0001] The present invention relates to the field of sensor technology, and in particular to a low-power winch sensor based on tunneling magnetoresistance effect. Background Art

[0002] The tunneling magnetoresistance (TMR) effect refers to the effect in which the tunnel resistance of a ferromagnetic-insulator thin film (approximately 1 nanometer)-ferromagnetic material varies with the relative orientation of the ferromagnetic materials on both sides. The TMR effect has unique advantages, such as large magnetoresistance and high magnetic field sensitivity, and thus presents very attractive application prospects. Compared with other magnetoresistance and Hall effect sensors, TMR has a higher output signal, a larger linear operating range, and higher sensitivity.

[0003] At present, TMR-based sensors can realize two detection functions. One is the detection of steering, which uses a TMR sensing unit to sense the polarity change of magnets spaced apart on the magnetic rotor, thereby determining the direction of rotation; the other is the detection of speed or angle of rotation, which uses one or two TMR sensing units to sense the magnetic resistance change of closely spaced magnets on the magnetic rotor, output a pulse voltage signal and calculate the speed or angle of rotation; however, the layout structure of existing TMR-based sensors can only support the test of speed or steering separately, and cannot simultaneously obtain the test of steering and speed by analyzing its output signal, which will limit the application scope of TMR sensors; in addition, the sensor assembly accuracy affects its detection error.

[0004] Based on this, the present invention optimizes the arrangement structure of the TMR sensing unit and the magnet on the magnet rotor and improves the assembly method so that the sensor meets the detection requirements of the winch's steering and speed synchronous detection. Summary of the Invention

[0005] An object of the present invention is to provide a low-power winch sensor based on tunneling magnetoresistance effect, thereby overcoming one or more problems caused by limitations and defects of related technologies, at least to a certain extent.

[0006] To achieve the above object, the present invention provides the following technical solutions:

[0007] A low-power winch sensor based on the tunneling magnetoresistance effect comprises a measurement module, a signal conversion unit, a housing, a core shaft, a magnetic turntable, and a detection assembly. One end of the core shaft is connected to a winch drum, and the magnetic turntable is connected to the core shaft and rotates synchronously. The detection assembly is encapsulated in the housing and comprises a TMR sensing element and N magnets. The magnetic turntable has N mounting blind holes evenly distributed around its rotation axis, and the magnets are cylindrical and embedded in the mounting blind holes and parallel to the rotation axis. The TMR sensing element is fixedly mounted on the housing and comprises a mounting plate, a first sensing unit, and a second sensing unit. The mounting plate is arranged parallel to and directly below the magnetic turntable. The first and second sensing units are located on the mounting plate, and their magnetic domain directions are perpendicular to the rotation axis. The magnetoresistance signals collected by the two sensing units are converted into square wave pulse signals by the signal conversion unit and input into the measurement module for analysis and calculation of the direction of rotation and speed. The horizontal distance R from the center of the first sensing unit, the second sensing unit, and the magnet to the rotation axis is the same, and the center distance L of the first and second sensing units is less than R×sin(180° / N).

[0008] Furthermore, the signal conversion unit includes an operational amplifier, a Schmitt trigger, a signal driving chip and a MOS tube push-pull circuit connected in series. The collected signal of the first sensing unit is converted and enhanced by the signal conversion unit to output a first square wave pulse signal. The collected signal of the second sensing unit is converted and enhanced by the signal conversion unit to output a second square wave pulse signal. The two signal conversion units output the first square wave pulse signal and the second square wave pulse signal with a phase difference to the measurement module, and the phase difference is less than the pulse width / 2.

[0009] Furthermore, a high-resistance resistor is connected in series to the access end of the measurement module, and the measurement module includes a pulse calculation unit and a steering judgment unit. The pulse calculation unit is used to calculate the rotational speed based on the number of pulses of the first square wave pulse signal or the second square wave pulse signal per unit time, and the steering judgment unit is used to judge the steering based on the corresponding relationship between the falling edge of the first square wave pulse signal and the resistance state of the second square wave pulse signal.

[0010] Furthermore, the first sensing unit and the second sensing unit both include a free layer, a barrier layer, and a reference layer arranged in sequence from bottom to top, and the two are fixed side by side on a substrate, which is an FR-4 glass fiber reinforced epoxy resin composite substrate, on which a copper circuit for connecting the first sensing unit and the second sensing unit is printed.

[0011] Furthermore, the shell is installed on the winch frame through a mounting bracket, and a turntable slot is provided in the shell. A bearing slot in the middle and a sensing slot near the side edge are provided at the bottom of the turntable slot. The TMR sensing element is fixedly installed in the sensing slot, and the core shaft includes a threaded connection section, a support section and a cam section. The threaded connection section is threadedly connected to the winch drum, and the support section is supported by a bearing in the bearing slot. The magnetic turntable is clamped and screwed to the cam section. An adjusting gasket is provided between the TMR sensing element and the bottom of the sensing slot for adjusting the distance between the TMR sensing element and the end face of the magnet.

[0012] Furthermore, the bearing groove is provided with two bearings to jointly support the support section, and the bearings and the support section are interference fit.

[0013] Furthermore, the mounting bracket elastically supports the shell, which includes a supporting inclined plate and two end plates formed by bending at both ends of the supporting inclined plate. One end plate is connected to the lower end surface of one side of the shell, and the other end plate is connected to the winch frame, which is used to elastically deform to adapt to the installation of the core shaft and provide elastic support for the end surface of the supporting section.

[0014] Furthermore, the shell is provided with a sealing plate to cover the notch of the turntable slot, a center hole is opened in the center of the sealing plate, the other end of the core shaft passes through the center hole and out of the turntable slot, and an operating head for rotating operation is provided.

[0015] Compared with the prior art, the low-power winch sensor based on the tunneling magnetoresistance effect of the present invention has the following beneficial effects:

[0016] The sensor is based on the TMR tunneling magnetoresistance effect, with high detection sensitivity and low energy consumption. The two sensing units are affected by the regular changes in the magnetic field of the annular distributed magnet, and successively present a high-resistance state or a low-resistance state. The signal is enhanced and converted into a square wave through the signal conversion unit, and the output is a square wave signal that can be accurately analyzed and calculated by the measurement module for rotating speed. The arrangement spacing of the two sensing units is controlled so that there is a phase difference in the square wave signals they output. This phase difference makes the square wave signals have different corresponding relationships under different steering directions, which is convenient for quickly and accurately judging the steering direction of the winch drum. In addition, the overall structure of the sensor is simple and the radial size is small. It uses a cylindrical magnet embedded in the disk as a source of variable magnetic field, which is easy to install and control the installation accuracy. The magnetic turntable and TMR sensing element are fixedly installed on different components respectively, and the core shaft is connected to the shell through a bearing, which can reduce the contact friction between the core shaft and the turntable and the shell, thereby improving the detection accuracy of the sensor. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 Disclosed is a structural perspective view of the sensor of the present invention;

[0018] Figure 2 An exploded view of the sensor components of the present invention is disclosed;

[0019] Figure 3A cross-sectional view of the sensor of the present invention is disclosed;

[0020] Figure 4 Public Figure 2 A three-dimensional diagram of the TMR sensing unit;

[0021] Figure 5 Schematic diagram of signal sensing of the detection device disclosed in the present invention;

[0022] Figure 6 for Figure 4 Schematic diagram of signals collected when the magnetic turntable rotates in the first direction;

[0023] Figure 7 for Figure 4 Schematic diagram of signals collected when the magnetic turntable rotates in the second direction;

[0024] Figure 8 This is a circuit diagram of the signal conversion unit of the sensor of the present invention.

[0025] In the figure: 1. Mounting bracket; 2. Core shaft; 3. Closing plate; 4. Housing; 41. Sensing slot; 5. Magnetic turntable; 51. Magnet; 6. TMR sensing element; 61. Mounting plate; 62. First sensing unit; 63. Second sensing unit; 64. Base plate; 7. Bearing; 8. Lead assembly. DETAILED DESCRIPTION

[0026] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only the best embodiments of the present invention, not all embodiments. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making any creative efforts shall fall within the scope of protection of the present invention.

[0027] This embodiment provides a low-power winch sensor based on the tunneling magnetoresistance effect, such as Figure 1-Figure 5 As shown, it includes a measuring module, a signal conversion unit, a housing 4, a core shaft 2, a magnetic turntable 51 and a detection component; wherein,

[0028] The core shaft 2 is used to transmit the rotation information of the winch drum. A threaded connection section, a support section, a cam section and an operating head are sequentially arranged on it. The threaded connection section at one end is threadedly connected to the winch drum and rotates synchronously around the rotation centerline of the winch drum. The cam section is snap-fitted and connected to the magnetic turntable 51 and connected to a synchronous rotation structure by screws. The support section is interference-fitted with a double bearing 7 to ensure the smooth rotation of the magnetic turntable 51 and effectively reduce the movement and jitter of the core shaft 2 during high-speed rotation.

[0029] The detection assembly is used to collect information about the rotation of the drum. It is enclosed in the housing 4 and a seal is provided to seal the gap between the housing 4 and the core shaft 2 to achieve dust and water protection. Specifically, the detection assembly includes a TMR sensing element 6 and N magnets 51. The upper surface of the magnetic turntable 51 is perpendicularly provided with N mounting blind holes adapted for the magnets 51. The N mounting blind holes are evenly distributed in a ring shape centered on the rotation axis of the magnetic turntable 51. The magnets 51 are cylindrical in structure and are embedded and fixed in the mounting blind holes. The magnets 51 are parallel to the rotation axis and their polarity directions are perpendicular to the surface of the magnetic turntable 51. The polarity directions of all magnets 51 are the same.

[0030] The TMR sensing element 6 is fixedly mounted on the housing 4. Figure 4 As shown, it includes a mounting plate 61, a substrate 64, a first sensing unit 62 and a second sensing unit 63. The first sensing unit 62 and the second sensing unit 63 are tunneling magnetoresistive sensing units. The two are arranged side by side and welded on the substrate 64. The substrate 64 is embedded in the mounting plate 61. The first sensing unit 62 and the second sensing unit 63 each include a free layer, a barrier layer, and a reference layer arranged in sequence from bottom to top. The magnetic domain directions of the free layer and the reference layer are both perpendicular to the rotation axis, as shown in FIG. Figure 5 As shown, under the influence of the change in magnetic field strength of the magnet 51, a tunneling current is generated on the tunneling magnetoresistance sensing unit, and presents a dynamic sinusoidal change. The changing magnetoresistance signal is collected by the signal conversion unit and converted into a square wave pulse signal, which is input into the measurement module for speed analysis and calculation;

[0031] In order to synchronously obtain analyzable signals of the steering direction and speed based on this sensor structure, the first sensing unit 62 and the second sensing unit 63 are located directly below the mounting loop of the magnet 51. That is, the horizontal distances from the centers of the first sensing unit 62 and the second sensing unit 63 to the rotation axis are respectively equal to the horizontal distances from the magnet 51 to the rotation axis, both being R, and the center distance L of the first sensing unit 62 and the second sensing unit 63 is less than R×sin(180° / N). Therefore, when the magnetic turntable 51 rotates, the magnetic resistance change pulses generated by the magnet 51 on the first sensing unit 62 and the second sensing unit 63 form a phase difference. Under different steering conditions, the signal outputs of the first sensing unit 62 and the second sensing unit 63 have different corresponding relationships, and the steering direction is obtained by analyzing the phase difference information.

[0032] In order to facilitate the installation and adjustment of the TMR sensing element 6, a turntable groove and a mounting hole are provided in the shell 4. The magnetic turntable 51 is arranged in the turntable groove without contact. A bearing groove is opened in the center of the bottom of the turntable groove. After the bearing 7 is interference-fitted on the support section of the core shaft 2, it is transition-fitted and installed in the bearing groove, and a retaining spring for end limiting is provided. The rotation axis of the core shaft 2 is colinear with the central axis of the shell 4. A sensing groove 41 is opened off-center at the bottom of the turntable groove. Two mounting screw holes are provided at the bottom of the sensing groove 41, and a lead hole penetrating the wall of the shell 4 is provided on its side. The lead assembly 8 can be detachably installed in the lead hole for fixing and protecting the signal and power leads of the TMR sensing element 6. A connecting hole connected to the mounting screw hole is provided on the mounting plate 61, and an adjustment gasket is provided at the bottom thereof for adjusting the distance between the TMR sensing element 6 and the bottom surface of the magnetic turntable 51.

[0033] As a further technical solution, the substrate 64 is a FR-4 glass fiber reinforced epoxy resin composite substrate 64, on which the signal connection circuit and the power supply circuit are printed. The signal conversion unit can be set on the substrate 64 and connected to the sensing unit. The measurement module is an external processing unit, such as Figure 8 As shown, the signal conversion unit includes an operational amplifier, a Schmitt trigger, a signal driver chip, and a MOS tube push-pull circuit connected in series. The sine waveform acquisition signal is amplified and square-wave converted, and then enhanced and output by the MOS tube push-pull circuit, thereby improving the calculation accuracy of the speed and direction. The acquisition signal of the first sensing unit 62 is level-converted and enhanced by the signal conversion unit, and then outputs a first square wave pulse signal. The acquisition signal of the second sensing unit 63 is level-converted and enhanced by the signal conversion unit, and then outputs a second square wave pulse signal. Since L is less than R×sin(180° / N), there is a phase difference between the first square wave pulse signal and the second square wave pulse signal, and the phase difference is less than the pulse width / 2. Figure 6 As shown, when rotating in the first direction, the square wave signal of the first sensing unit 62 is delayed by a phase difference compared to the square wave signal of the second sensing unit 63, that is, when the signal wave of the first sensing unit 62 enters the falling edge, the second sensing unit 63 is already at a low resistance level; Figure 7 As shown, when rotating in the second direction, the square wave signal of the first sensing unit 62 is ahead of the square wave signal of the second sensing unit 63 by a phase difference, that is, when the signal wave of the first sensing unit 62 enters the falling edge, the second sensing unit 63 is still at a high impedance state level; accordingly, the measurement module can accurately analyze the direction of rotation of the winch drum.

[0034] As a further technical solution, a high-resistance resistor is connected in series to the access end of the measuring module (not shown in the figure). When its input impedance reaches 1KΩ, the sensor power consumption can be reduced to 2mW to further achieve the purpose of extremely low power consumption. The measuring module has a built-in pulse calculation unit and a steering judgment unit. The pulse calculation unit counts the number of pulses of the first square wave pulse signal or the second square wave pulse signal and calculates the output drum speed. According to the above method, the steering judgment unit judges the drum direction based on the corresponding relationship between the falling edge of the first square wave pulse signal and the resistance state of the second square wave pulse signal.

[0035] As a further technical solution, the structure and installation of the sensor must meet the requirements of synchronous transmission of the rotational motion on the magnetic turntable 51 and relative static collection of the TMR sensing element 6. In order to meet the installation requirements and precise assembly, the housing 4 is installed on the winch frame through an elastically supported mounting bracket 1, such as Figure 1-Figure 3 As shown, the mounting bracket 1 includes a supporting inclined plate and two end plates formed by bending at both ends of the supporting inclined plate. One end plate is connected to the lower end surface of one side of the shell 4, and the other end plate is connected to the winch frame. When installing the sensor, first, fix the mounting bracket 1 to position and initially support the sensor. Since the mounting bracket 1 has a certain elastic deformation, the shell 4 can be fine-tuned to adapt to the installation of the core shaft 2. After the installation is completed, the mounting bracket 1 generates an elastic supporting force in the opposite direction to the fixing direction of the core shaft 2 to prevent the core shaft 2 and the shell 4 from moving relative to each other, thereby ensuring assembly reliability.

[0036] In addition, an operating head for rotating operation is provided at the other end of the core shaft 2. A center hole is opened in the center of the sealing plate 3 of the turntable slot of the shell 4. The core shaft 2 extends out of the center hole through the other end. The operating head located outside the turntable slot can facilitate the twisting and disassembly of the core shaft 2.

[0037] The directional words such as "inside", "outside", "upper", "lower", "side", and "end" mentioned in this article are based on Figure 1-Figure 5 The coordinates or orientations shown in . These terms are mainly used to better describe the present invention and its embodiments, and are not intended to limit the indicated devices, elements or components to have a specific orientation, or to be constructed and operated in a specific orientation;

[0038] Furthermore, some of the above terms may be used to express other meanings besides indicating a direction or positional relationship. For example, the terms "on" and "in" may also be used to express a dependency or connection relationship in certain circumstances. Those skilled in the art will understand the specific meanings of these terms in the present invention based on the specific circumstances.

[0039] While embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions, and variations may be made to these embodiments without departing from the principles and spirit of the invention, and that the scope of the invention is defined by the appended claims and their equivalents.

Claims

1. A low-power winch sensor based on tunneling magnetoresistance effect, characterized by: The invention comprises a measurement module, a signal conversion unit, a housing, a core shaft, a magnetic turntable and a detection assembly; one end of the core shaft is connected to the winch drum, the magnetic turntable is connected to the core shaft and rotates synchronously, the detection assembly is encapsulated in the housing, and comprises a TMR sensing element and N magnets. The disk surface of the magnetic turntable is provided with N mounting blind holes evenly distributed around its rotation axis. The magnets are cylindrical in structure and embedded in the mounting blind holes and parallel to the rotation axis. The TMR sensing element is fixedly mounted on the housing and comprises a mounting plate, a first sensing unit and a second sensing unit. The mounting plate is arranged parallel to and directly below the magnetic turntable. The first sensing unit and the second sensing unit are located on the mounting plate, and their magnetic domain directions are perpendicular to the rotation axis. The magnetic resistance signals collected by the two are converted into square wave pulse signals by the signal conversion unit and input into the measurement module for analysis and calculation of the direction and speed. The horizontal distance R from the center of the first sensing unit, the second sensing unit and the magnet to the rotation axis is the same, and the center distance L of the first sensing unit and the second sensing unit is less than R×sin(180° / N).

2. The low-power winch sensor based on tunneling magnetoresistance effect according to claim 1, characterized in that: The signal conversion unit includes an operational amplifier, a Schmitt trigger, a signal driver chip, and a MOS tube push-pull circuit connected in series. The acquisition signal of the first sensing unit is converted and enhanced by the signal conversion unit to output a first square wave pulse signal. The acquisition signal of the second sensing unit is converted and enhanced by the signal conversion unit to output a second square wave pulse signal. The two signal conversion units output the first square wave pulse signal and the second square wave pulse signal with a phase difference to the measurement module, and the phase difference is less than the pulse width / 2.

3. The low-power winch sensor based on tunneling magnetoresistance effect according to claim 2, characterized in that: A high-resistance resistor is connected in series to the access end of the measurement module. The measurement module includes a pulse calculation unit and a steering judgment unit. The pulse calculation unit is used to calculate the rotational speed based on the number of pulses of the first square wave pulse signal or the second square wave pulse signal per unit time. The steering judgment unit is used to judge the steering based on the correspondence between the falling edge of the first square wave pulse signal and the resistance level of the second square wave pulse signal.

4. The low-power winch sensor based on tunneling magnetoresistance effect according to claim 2, characterized in that: The first sensing unit and the second sensing unit both include a free layer, a barrier layer, and a reference layer arranged in sequence from bottom to top, and the two are fixed side by side on a substrate. The substrate is an FR-4 glass fiber reinforced epoxy resin composite substrate, on which a copper circuit for connecting the first sensing unit and the second sensing unit is printed.

5. The low-power winch sensor based on tunneling magnetoresistance effect according to any one of claims 1 to 4, characterized in that: The shell is installed on the winch frame through a mounting bracket, and a turntable groove is provided in the shell. The bottom of the turntable groove is provided with a bearing groove located in the middle and a sensing groove near the side edge. The TMR sensing element is fixedly installed in the sensing groove, and the core shaft includes a threaded connection section, a support section and a cam section. The threaded connection section is threadedly connected to the winch drum, and the support section is supported by the bearing in the bearing groove. The magnetic turntable is clamped and screwed to the cam section. An adjusting gasket is provided between the TMR sensing element and the bottom of the sensing groove for adjusting the distance between the TMR sensing element and the end face of the magnet.

6. The low-power winch sensor based on tunneling magnetoresistance effect according to claim 5, characterized in that: The bearing groove is provided with two bearings to jointly support the support section, and the bearings and the support section are in interference fit.

7. The low-power winch sensor based on tunneling magnetoresistance effect according to claim 5, characterized in that: The mounting bracket elastically supports the shell, and includes a supporting inclined plate and two end plates formed by bending at both ends of the supporting inclined plate. One of the end plates is connected to the lower end surface of one side of the shell, and the other end plate is connected to the winch frame, which is used for elastic deformation to adapt to the installation of the core shaft and provide elastic force to support the end surface of the support section.

8. The low-power winch sensor based on tunneling magnetoresistance effect according to claim 5, characterized in that: The shell is provided with a sealing plate to cover the notch of the turntable slot, a center hole is provided at the center of the sealing plate, the other end of the core shaft passes through the center hole and out of the turntable slot, and an operating head for rotating operation is provided.

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