Electromagnet armature motion detection method

Abstract

The invention discloses an electromagnet armature motion detection method. The technical problems that an existing electromagnet armature is high in motion detection cost and poor in anti-interference performance, and the size of an electromagnet is increased due to the fact that a sensor is additionally arranged are mainly solved. According to the method, the output signal of the magnetic sensor is measured and collected in the process of gradually increasing or decreasing the control current flowing through the coil, and the existence of response action of the armature is judged based on the non-linear change stage or jump of the change trend line of the output signal. According to the detection method, by recognizing the nonlinear change stage or jump existing in the output signal of the magnetic sensor, whether the armature has the response action or not can be judged conveniently, rapidly and accurately, the anti-interference performance is high, the detection reliability and the detection efficiency are high, and the size of the electromagnet cannot be increased.

Description

Technical Field

[0001] The present invention relates to the technical field of electromagnets, and in particular to a method for detecting the action of an electromagnet armature. Background Art

[0002] An electromagnet is a device that uses the electromagnetic effect to generate a magnetic field and then respond to corresponding control actions. It is usually composed of an iron core and a coil. When the coil is energized, a magnetic field is generated, which magnetizes the iron core, thereby generating an attractive force. The armature is an important component in the electromagnet. It is usually adjacent to the iron core and moves or maintains a certain position through the action of magnetic force. The armature is generally made of soft magnetic material. This is because soft iron has the characteristics of easy magnetization and easy loss of magnetism, which allows the armature to be quickly magnetized and attracted when the electromagnet is energized, and quickly loses magnetism and resets when the power is off. When the electromagnet is energized, the magnetic field generated by the coil will magnetize the iron core and the armature, forming a magnetic force that attracts each other. When this magnetic force is greater than the spring force or other resistance on the armature, the armature will move toward the direction of the iron core, thereby completing the closure of the circuit or the action of the mechanical device. When the electromagnet is de-energized, the magnetic field disappears, and the armature returns to its original position under the action of the spring force or other reset mechanism, and the circuit is disconnected or the mechanical device is reset.

[0003] In many automated control systems and mechanical equipment, accurate detection of the armature position is the key to achieving precise control and positioning. If the armature position is inaccurate or unstable, the system control accuracy will be reduced, or even cause failures. In some occasions with high safety requirements, such as elevators, cranes and other equipment, the reliability of the armature's action position is directly related to the safety performance of the equipment. If the armature position detection is inaccurate or the action response fails, it will cause the equipment to lose control or an accident. Therefore, reliable and accurate feedback detection of the armature action response is required to ensure that the armature reliably responds to control instructions.

[0004] The inventor knows a method of detecting the armature action position by means of a linear displacement sensor, but this method is not sufficiently resistant to interference from external magnetic fields, and requires the linear displacement sensor to be installed along the axial direction of the electromagnet and the armature action end to be extended accordingly, which makes the electromagnet larger and the detection cost higher.

[0005] The information disclosed in this background technology section is only used to deepen the understanding of the background technology of the present disclosure, and should not be regarded as acknowledging or suggesting in any form that the information constitutes the prior art known to those skilled in the art. Summary of the invention

[0006] In view of at least one of the above technical problems, the present disclosure provides a method for detecting the action of an electromagnet-armature, which mainly solves the technical problems that the existing electromagnet-armature action detection has high cost, insufficient anti-interference performance and the addition of a sensor causes the size of the electromagnet to increase.

[0007] According to one aspect of the present disclosure, a method for detecting the action of an electromagnet armature is provided, wherein the electromagnet comprises an iron core, a guide sleeve provided at one end of the iron core and used for embedding an armature, a coil provided at the outer edge of the iron core, and a magnetic sensor provided at the corresponding end of the guide sleeve. The output signal of the magnetic sensor is measured and collected in the process of gradually increasing or decreasing the control current flowing through the coil, and the armature is judged to have a response action based on the existence of a nonlinear change stage or jump in the change trend line of the output signal.

[0008] In some embodiments of the present disclosure, the magnetic sensor is an MR sensor or a Hall sensor.

[0009] In some embodiments of the present disclosure, when a voltage of a corresponding level is applied to the coil, the output signal of the magnetic sensor corresponds to the position of the armature.

[0010] In some embodiments of the present disclosure, the sampling frequency of the output signal of the magnetic sensor is not less than 1 KHz.

[0011] In some embodiments of the present disclosure, a coordinate system is established with the output signal of the magnetic sensor as the vertical axis and the control current of the coil as the horizontal axis. When the slope of the output signal curve in the coordinate system increases or decreases by at least 1.5 times, it is determined that the change trend line of the output signal has the nonlinear change stage or jump, and then it is determined that the armature has moved.

[0012] In some embodiments of the present disclosure, the electrical delay time of the armature after the coil is energized is t1, and the designed action time of the armature is t2, and the difference of the output signal of the magnetic sensor corresponding to time X and time Y is measured and obtained, and the occurrence of the nonlinear change stage or jump is determined based on the output signal difference being greater than M; wherein 0 <X<t1,Y> t1+t2; M is the output signal difference of the magnetic sensor at time X and time Y when the armature is fixed.

[0013] One or more technical solutions provided in the embodiments of the present application have at least any of the following technical effects or advantages: The detection of the armature action is achieved based on the magnetic sensor embedded in the end of the electromagnet, which can avoid the limitation of the use scenario of the electromagnet due to the increase in volume; at the same time, by identifying the nonlinear change stage or jump in the output signal of the magnetic sensor, it is possible to quickly and accurately determine whether the armature has responded. It has strong anti-interference ability, high detection reliability and efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 Schematic diagram of the structure of an electromagnet in one embodiment of the present application.

[0015] Figure 2 1 is a curve diagram of the output signal of the magnetic sensor under different end point air gaps in one embodiment of the present application.

[0016] Figure 3 This is a graph showing the slope change of the magnetic sensor output signal under different end point air gaps in one embodiment of the present application.

[0017] Figure 4 This is a curve diagram of the sensor output signal as the coil voltage changes according to an embodiment of the present application.

[0018] In the above figures, 1 is the iron core, 2 is the guide sleeve, 3 is the armature, 4 is the coil, 5 is the end cap, and 6 is the magnetic sensor. DETAILED DESCRIPTION

[0019] In the description of the present application, it should be understood that the terms "up", "down", "front", "back", "left", "right", "top", "bottom", "inside", "outside", "vertical", "horizontal", "clockwise", "counterclockwise", etc., indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying 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.

[0020] The programs involved or relied upon in the following embodiments are all conventional programs or simple programs in the technical field, and those skilled in the art can make conventional selections or adaptive adjustments according to specific application scenarios. The devices involved in the following embodiments, unless otherwise specified, are all conventional commercially available products.

[0021] In order to better understand the technical solution of the present application, the above technical solution will be described in detail below in conjunction with the accompanying drawings and specific implementation methods.

[0022] In order to solve the technical problems that the existing electromagnetic armature action detection has high cost, insufficient reliability (poor anti-interference performance) and the need to install a linear displacement sensor, which makes the electromagnet larger and limits the use of the electromagnet, this example discloses an electromagnetic armature action detection method.

[0023] In this embodiment, see Figure 1The electromagnet includes an iron core 1, one end of which is coaxially connected to a guide sleeve 2. In this example, the outer diameter of the guide sleeve 2 matches the outer diameter of the iron core, and the guide sleeve 2 is provided with a cavity for installing an armature 3 along its axis. The armature 3 is embedded in the cavity of the guide sleeve 2 to move along the axial direction of the guide sleeve 2. In addition, a coil 4 is provided outside the iron core 1 through a supporting frame, and the coil 4 is provided with a terminal at the outer shell of the electromagnet for connecting a power source to provide current to the coil 4. In addition, a reset elastic member is provided at the other end of the electromagnet. In this embodiment, the reset elastic member is specifically a reset spring. When the coil 4 is connected to the power source through the terminal at the electromagnet housing, current flows through the coil 4, thereby generating a magnetic field. The magnetic field acts on the iron core to generate an electromagnetic force, which then adsorbs the armature, overcomes the elastic force of the reset spring, and causes the armature to move axially along the guide sleeve 2, thereby realizing the action of the electromagnet.

[0024] In order to detect the armature action, in this embodiment, see Figure 1 , an end cap 5 is provided at the end of the guide sleeve 2. On the one hand, the end cap 5 is used to close the end of the guide sleeve 2 to prevent the armature from slipping out; on the other hand, a magnetic sensor is embedded in the end cap 5 to detect the internal magnetic field of the electromagnet, thereby detecting the movement of the armature. Specifically, in this example, the magnetic sensor is an MR sensor, and in some other embodiments, the magnetic sensor is a Hall sensor. In order to achieve accurate and reliable detection of the magnetic field by the magnetic sensor, the normal of the magnetic sensor is set to be perpendicular to the running direction of the armature. In this example, the magnetic sensor is welded to the PCB board, so the plane where the PCB board is located is set to be parallel to the movement direction of the armature.

[0025] After the magnetic sensor is firmly embedded in the end cap at the corresponding end of the guide sleeve, the wiring terminal of the coil 4 at the electromagnet housing is connected to the power supply, and the magnetic sensor is powered to start the magnetic sensor for magnetic field detection. Thus, by applying a voltage of a corresponding level to the wiring terminal of the coil, the output signal of the magnetic sensor can reflect the position state of the armature. On the whole, there is a corresponding linear or nonlinear relationship between the output signal of the magnetic sensor and the distance moved by the armature. Based on such characteristics, it is easy to resolve the movement position of the armature. However, once it is interfered by strong external magnetic field, the output signal of the magnetic sensor will drift, which will lead to errors or misjudgments in the armature movement position resolution.

[0026] The inventor found in long-term experimental research that the curves of the magnetic sensor output signal are different when the terminal air gap at the armature movement position is different. The terminal air gap refers to the distance between the end face of the armature and the end face of the core close to the armature at the end position of the armature movement. Based on this, the inventor conducted a further series of experiments, setting (non-magnetized) gaskets of different thicknesses between the end faces of the armature and the core to control the size of the terminal air gap. The results are shown in Figure 2, the output signal curve of the magnetic sensor was obtained at different terminal air gaps. When the terminal air gap Gap=3.4mm (i.e., there is no displacement space for the armature), the armature remains fixed from beginning to end and does not change position. When the terminal air gaps are 0.2mm and 1.8mm, respectively, the change trend line of the output signal of the magnetic sensor shows a nonlinear change stage (or jump); based on this regular feature, it can be determined whether the position of the armature has changed according to whether the change trend line of the output signal of the magnetic sensor has a nonlinear change stage (or jump). Further research shows that even if it is subject to strong external magnetic interference, the change trend line of the output signal of the magnetic sensor will have an overall upward or downward shift, but it still has the above-mentioned nonlinear stage or jump (mutation). Based on the identification of this nonlinear change stage or jump, the response action of the armature can still be accurately and reliably detected.

[0027] Based on the above-mentioned law found by the inventor, in this example, when the electromagnetic armature action detection is performed, the magnetic sensor is connected to the sampling circuit accordingly, and the sampling circuit samples the output signal of the magnetic sensor according to the set frequency. In this embodiment, the sampling frequency of the sampling circuit is set to be not less than 1KHz, thereby avoiding the sampling interval being too large and resulting in the inability to timely and effectively detect and reflect the response action of the armature. After the coil is connected to the power supply and the magnetic sensor is powered on, the electromagnetic armature action detection is started; first, the power supply corresponding to the coil is started according to the control requirements, and the control current flowing through the coil gradually increases. At this time, the magnetic field around the coil increases with the increase of the control current, and the electromagnetic force generated by the magnetic field also increases accordingly, gradually reaching the threshold value of overcoming the static friction force and the elastic force of the reset spring on the armature, thereby driving the armature to produce a response action. In the process of increasing the coil current, the sampling circuit continuously samples the output signal of the magnetic sensor according to the set frequency, establishes a coordinate system with the output signal and the coil current as the corresponding vertical and horizontal axes, calculates the change slope of the output signal curve between adjacent sampling points, and compares the ratio of the slope of the signal curve between adjacent sampling intervals. In this embodiment, see Figure 3 ,Will Figure 2 The amplitude change of the magnetic sensor output signal is converted into Figure 3 In this example, when the ratio of the slopes of the output signal curves between adjacent sampling intervals is greater than 2, the trend line of the output signal of the magnetic sensor has an obvious nonlinear change stage (jump), and the armature is judged to respond to the corresponding control signal. In some other embodiments, when the ratio of the slopes of the signal curves between adjacent sampling intervals is greater than 1.5, the trend line of the output signal of the magnetic sensor also has a nonlinear change stage, which corresponds to the instantaneous response of the armature.

[0028] Similarly, after the armature produces the adsorption action, in the process of releasing the armature as the control demand changes, as the control voltage applied to the corresponding terminal of the coil decreases, the control current (coil current) flowing through the coil gradually decreases, thereby reducing the magnetic field generated by the coil being energized, and the electromagnetic force corresponding to the magnetic field gradually disappears. Since a reset spring is provided on the corresponding end side of the electromagnet, the armature is reset to the initial position under the elastic force of the reset spring. In order to detect the armature action during the reset process, the output signal of the magnetic sensor during the gradual decrease of the control current in the coil is sampled by the sampling circuit according to the set sampling frequency, and the change slope between adjacent sampling points on the output signal curve is calculated, and the ratio of the slopes between adjacent sampling intervals on the output signal curve is compared. In this embodiment, the slope ratio of adjacent sampling points is greater than 2, that is, at this time, the change trend of the output signal of the magnetic sensor shows nonlinear changes or jumps, and it is determined that the armature cannot overcome the elastic force of the reset spring and moves under its action.

[0029] In this embodiment, the wiring terminals corresponding to the electromagnet coil are connected to a programmable voltage source, which applies a control voltage to the coil to generate a control current, and the programmable voltage source is connected to the PC through a signal line to obtain a control signal from the PC and output a corresponding control voltage in response to the control signal. The power supply wiring terminals of the magnetic sensor are connected to a power supply of the corresponding level, and its signal output is connected to a digital multimeter, which is in turn connected to the PC to sample the signal output by the magnetic sensor, and perform an electromagnet armature action detection test based on this. Specifically, the programmable voltage source is adjusted so that the voltage at both ends of the wiring terminals corresponding to the coil gradually increases from 0 to 24V, and the magnetic sensor signal output during the process is sampled. For the results, see Figure 4 In the figure, the horizontal axis Coil Voltage represents the voltage applied to the coil, and the vertical axis Sensor output represents the output voltage of the magnetic sensor. It can be seen from the figure that when the coil voltage is 7V, the slope of the magnetic sensor output signal curve changes significantly. Compared with the previous sampling cycle, the slope increases by 2 times. In this example, a video monitoring device is used to monitor the position of the armature action end, and synchronized with the magnetic sensor output signal sampling cycle, and the armature action end position is synchronously photographed at the magnetic sensor sampling node. Through analysis, it is found that when the slope of the magnetic sensor output signal curve changes by no less than 1.5 times, it can be determined that the armature has actuated. Similarly, see Figure 2 In the process of the coil voltage dropping from 24V to 0V, the slope of the output signal of the magnetic sensor changes significantly when the coil voltage is 5V. Compared with the previous sampling period, its slope increases by 2 times. Based on this, it can be determined that the armature has a response action under the action of the reset spring force.

[0030] In some other embodiments, in order to determine whether the trend line of the output signal change of the magnetic sensor has the above-mentioned nonlinear change stage, the electrical delay time of the armature after the coil is energized is set to t1, and the electrical delay time t1 represents the time interval between the moment when the coil is energized and the moment when the armature starts to move; the designed action time of the armature is set to t2, and the designed action time t2 represents the time consumed by the armature from the start moment to the end moment of the action under ideal conditions. Therefore, after the coil is energized, the output signal amplitude of the magnetic sensor corresponding to the time X and the time Y are measured respectively, and the amplitude difference corresponding to the two time pairs is obtained to determine whether the output signal difference is greater than M, thereby determining whether the above-mentioned nonlinear change stage or jump occurs; wherein 0 <X<t1,Y> t1+t2; thus, the first output signal sampling at time X occurs before the designed action time of the armature, and the second output signal sampling at time Y occurs after the designed action time of the armature, and M is the difference between the output signals of the magnetic sensor at time X and time Y when the armature is fixed, that is, when the armature is always kept in the same position under the excitation of the coil. Therefore, judging whether the armature is actuated by the difference can offset the interference of the external magnetic field, avoiding the problem that the output of the magnetic sensor is affected by the external magnetic field interference, thereby affecting the judgment of the armature action. See Figure 2 In this embodiment, the curve corresponding to Gap=3.4mm is the output curve of the magnetic sensor when the armature is fixed. In this example, the X moment corresponds to the moment when the voltage is 5V, and the Y moment corresponds to the moment when the voltage is 15V. When the armature is fixed, the magnetic sensor output signal S corresponding to the Y moment 2（Gap=3.4mm） =41mV, the magnetic sensor output signal S corresponding to time X 1（Gap=3.4mm） =13mV, so we can get M=S 2（Gap=3.4mm） -S 2（Gap=3.4mm） =28mV. When there is no external magnetic field interference, the magnetic sensor output signal S corresponding to time Y 2（Gap=0.2mm） =50.6mV, the magnetic sensor output signal S corresponding to time X 1（Gap=0.2mm） =13mV, so the difference between the two is 37.6mV, which is greater than M, so it can be judged that the armature has responded to the control signal and has taken action. When there is magnetic field interference from the outside, due to S 1（Gap=0.2mm） and S 1（Gap=0.2mm） At the same time, the difference between the two can offset the external magnetic field interference, thus avoiding misjudgment and ensuring detection accuracy.

[0031] It can be seen that the method of the present application can meet the scenario where it is necessary to accurately determine whether the armature action responds or not, and is particularly suitable for electromagnet action state detection in complex electromagnetic environments. It has strong anti-interference ability and accurate and reliable state judgment.

[0032] Although some preferred embodiments of the present application have been described, those skilled in the art may make other changes and modifications to these embodiments once they have learned the basic creative concept. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments and all changes and modifications that fall within the scope of the present application.

[0033] Obviously, those skilled in the art can make various changes and modifications to the present invention without departing from the spirit and scope of the inventive concept. Thus, if these modifications and variations of the present application fall within the scope of the claims of the present application and their equivalents, the present application is also intended to include these modifications and variations.

Claims

1. A method for detecting the action of an electromagnet armature, wherein the electromagnet comprises an iron core, a guide sleeve disposed at one end of the iron core and used to embed the armature, a coil disposed at the outer edge of the iron core, and a magnetic sensor disposed at the corresponding end of the guide sleeve, characterized in that: The output signal of the magnetic sensor is measured and collected during the process of gradually increasing or decreasing the control current flowing through the coil, and the armature is determined to have a response action based on the existence of a nonlinear change stage or jump in the change trend line of the output signal.

2. The electromagnetic armature action detection method according to claim 1, characterized in that: The magnetic sensor is an MR sensor or a Hall sensor.

3. The electromagnetic armature action detection method according to claim 1, characterized in that: When a voltage of a corresponding level is applied to the coil, the output signal of the magnetic sensor corresponds to the position of the armature.

4. The electromagnetic armature action detection method according to claim 1, characterized in that: The sampling frequency of the output signal of the magnetic sensor is not less than 1 KHz.

5. The electromagnetic armature action detection method according to claim 1 or 4, characterized in that: A coordinate system is established with the output signal of the magnetic sensor and the control current of the coil as the corresponding vertical and horizontal axes respectively. When the slope of the output signal curve under the coordinate system increases or decreases by at least 1.5 times, it is determined that the change trend line of the output signal has the nonlinear change stage or jump, and then it is determined that the armature has moved.

6. The electromagnetic armature action detection method according to claim 1, characterized in that: Assume that the electrical delay time of the armature after the coil is energized is t1, and the designed action time of the armature is t2, measure and obtain the output signal difference of the magnetic sensor corresponding to time X and time Y, and judge that the nonlinear change stage or jump occurs according to the output signal difference being greater than M; wherein 0 <X<t1,Y> t1+t2; M is the output signal difference of the magnetic sensor at time X and time Y when the armature is fixed.

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