Cylinder position switch sensor

Abstract

The application discloses a kind of cylinder position switch sensors, belong to automation pneumatic control and industrial sensor technical field.The sensor includes magnetic sensitive sensing unit, axial signal processing unit, radial signal processing unit, logic gate unit and drive unit;Magnetic sensitive sensing unit synchronously collects axial, radial magnetic flux generated by cylinder piston movement and is converted into two-way electric signal.Logic gate unit only when axial signal reaches standard, radial signal zero-crossing, output valid level to drive unit, to make its output control signal.The application realizes the efficient filtering of hardware level space stray magnetic field by the cooperation of multi-path magnetic field and logic gate, has excellent anti-electromagnetic interference performance, can effectively eliminate the detection misjudgment, missing judgment problem caused by the size of magnetic ring in cylinder, significantly improves the accuracy of magnetic field determination and the overall operation stability of equipment.

Description

Technical Field

[0001] This invention relates to the field of automated pneumatic control and industrial sensor technology, and in particular to a cylinder position switch sensor. Background Technology

[0002] As a core actuator in automated production lines, cylinders, with their accompanying magnetic switches used for precise piston position detection, are widely used in industrial scenarios such as machining and automotive assembly. However, industrial cylinder manufacturers (such as Airtac and SMC) lack unified standards in terms of cylinder wall thickness, materials, and piston magnet dimensions and magnetization strength. This results in poor compatibility of traditional fixed-sensitivity magnetic switches, easily leading to issues such as position misalignment and missed triggering. Even with pre-screening of magnetic rings, there is still a risk of position misidentification.

[0003] Furthermore, production line assembly is divided into two methods: centering and eccentric installation. Under eccentric installation, a three-dimensional spatial misalignment will occur between the sensor and the magnet, which can easily cause multiple false sensing points in traditional single-axis threshold switches, thereby reducing the stability of equipment operation.

[0004] On the other hand, traditional technical solutions typically use magnetic sensors with only a single sensitive direction for signal acquisition, and the signal judgment logic often relies on preset fixed thresholds. However, in complex or extreme application scenarios, this single-dimensional perception and static judgment mechanism is highly susceptible to environmental interference, leading to missed detections or false triggers, which seriously affects the accuracy of detection and the stability of the system.

[0005] The information disclosed in this background section is intended only to enhance the understanding of the overall background of the invention and should not be construed as an admission or in any way implying that the information constitutes prior art known to those skilled in the art. Summary of the Invention

[0006] The purpose of this invention is to provide a cylinder position switch sensor, which has excellent anti-electromagnetic interference performance, can effectively eliminate the detection misjudgment and missed judgment caused by the different sizes of the magnetic rings inside the cylinder, significantly improve the accuracy of magnetic field determination and the overall operational stability of the equipment, and can be adapted to various specifications and types of cylinders.

[0007] To achieve the above objectives, embodiments of the present invention provide a cylinder position switch sensor, comprising:

[0008] The magnetic sensing unit is configured to detect the axial magnetic flux and radial magnetic flux generated when the cylinder piston moves, and convert the axial magnetic flux and radial magnetic flux into axial electrical signals and radial electrical signals, respectively.

[0009] An axial signal processing unit, connected to the magnetic sensing unit, is configured to determine whether the axial electrical signal meets a preset condition compared with a reference signal, and output a valid signal when the preset condition is met, and output an invalid signal when the preset condition is not met.

[0010] A radial signal processing unit, connected to the magnetic sensing unit, is configured to determine whether the radial electrical signal has crossed zero, and output a valid signal when it has crossed zero, and output an invalid signal when it has not crossed zero.

[0011] The logic gate unit is connected to both the axial signal processing unit and the radial signal processing unit, and is configured to output a valid signal when both the axial signal processing unit and the radial signal processing unit output valid signals.

[0012] The driving unit, connected to the logic gate unit, is configured to output a control signal when a valid signal is received from the logic gate unit.

[0013] In one or more embodiments of the present invention, the axial signal processing unit includes

[0014] The reference signal input unit is configured to input a reference signal;

[0015] The first comparator has one input connected to a magnetic sensing unit, another input connected to a reference signal input unit, and an output connected to a logic gate unit. It is configured to compare an axial signal with a reference signal and output a valid signal when the axial signal is greater than the reference signal and an invalid signal when the axial signal is less than the reference signal.

[0016] In one or more embodiments of the present invention, the reference signal input unit includes a reference voltage input terminal and a voltage divider circuit, the voltage divider circuit being connected between the reference voltage input terminal and the input terminal of the first comparator, and the reference voltage input terminal being able to connect to reference voltages of different magnitudes.

[0017] In one or more embodiments of the present invention, the reference voltage input terminal may be selectively connected to any one of a plurality of reference voltages, which are output via a low-dropout linear regulator.

[0018] In one or more embodiments of the present invention, the radial signal processing unit includes

[0019] The reference signal input unit is configured to input a reference signal;

[0020] The second comparator has one input connected to a magnetic sensing unit, another input connected to a reference signal input unit, and an output connected to a logic gate unit. It is configured to compare a radial signal with a reference signal and output a valid signal when the two match. The reference signal is a zero magnetic field voltage signal.

[0021] In one or more embodiments of the present invention, the logic gate unit includes

[0022] An AND gate, wherein the two input terminals of the AND gate are respectively connected to an axial signal processing unit and a radial signal processing unit, is configured to output a valid signal when both the axial signal processing unit and the radial signal processing unit output valid signals.

[0023] In one or more embodiments of the present invention, the driving unit includes

[0024] The first transistor and the second transistor are connected in series between the power supply and ground. The common node formed by their series connection forms the control signal output terminal. The gates of the first transistor and the second transistor are interconnected and further connected to the output terminal of the power transistor driver.

[0025] The power transistor driver has its input connected to a logic gate unit and is configured to output a drive signal when the logic gate unit outputs a valid signal, so as to control one of the first transistor and the second transistor to conduct.

[0026] In one or more embodiments of the present invention, the driving unit further includes

[0027] The drive mode selection input terminal is connected to the power transistor driver and is configured to receive an externally input drive mode selection signal so that the power transistor driver outputs a corresponding drive level according to the received drive mode selection signal, thereby controlling the first transistor and the second transistor to selectively conduct.

[0028] In one or more embodiments of the present invention, the driving unit includes

[0029] The delay unit includes a constant current source and a delay function pin connected to the constant current source. The delay function pin can be connected to a passive timing capacitor with an adjustable size. The constant current source is configured to charge the passive timing capacitor. The driving unit can collect the voltage across the timing capacitor in real time and output a control signal when the voltage reaches a preset threshold.

[0030] In one or more embodiments of the present invention, the driving unit further includes an overcurrent protection unit, wherein the second transistor is grounded through the overcurrent protection unit, and the overcurrent protection unit includes...

[0031] A sampling resistor, one end of which is connected to the second transistor to form a sampling node, and the other end is grounded;

[0032] The overcurrent protection module, connected to the sampling node, is configured to acquire the voltage signal across the sampling resistor in real time and trigger protection when the sampling voltage exceeds a preset threshold.

[0033] Compared with the prior art, (1) the present invention uses dual-axis magnetic field sampling combined with hardware AND gate logic to perform signal filtering, and relies on hardware circuits to complete the filtering operation of spatial stray magnetic field in real time, so as to achieve hardware-level stray interference fast filtering, effectively shielding the spatial stray magnetic field brought by the equipment cylinder and surrounding electromagnetic devices, avoiding stray signals from interfering with the effective signal of the magnet, greatly improving the accuracy of magnetic signal recognition, and the anti-interference ability is significantly better than the software filtering scheme.

[0034] (2) The present invention is a pure hardware signal processing architecture. It uses an operational amplifier to replace the ADC analog-to-digital conversion chip and single-chip microcontroller control unit in the traditional scheme, eliminating the faulty links such as software program, clock timing, and digital communication. There are no hidden dangers such as program crashes, system crashes, or abnormal software logic. The circuit link is simple, and the working stability is stronger under high and low temperature and complex working conditions, and the equipment failure rate is greatly reduced. Attached Figure Description

[0035] Figure 1 This is a schematic diagram of a cylinder position switch sensor structure according to an embodiment of the present invention;

[0036] Figure 2 This is a schematic diagram of a cylinder position switch sensor circuit according to an embodiment of the present invention;

[0037] Figure 3 This is a schematic diagram of the axial and radial signal processing unit structure according to an embodiment of the present invention;

[0038] Figure 4 This is a circuit schematic diagram of a magnetic sensing unit according to an embodiment of the present invention;

[0039] Figure 5 This is a circuit schematic diagram of an axial and radial signal processing unit according to an embodiment of the present invention;

[0040] Figure 6 This is a diagram of axial and radial magnetic field data according to an embodiment of the present invention. Detailed Implementation

[0041] The specific embodiments of the present invention will now be described in detail with reference to the accompanying drawings, but it should be understood that the scope of protection of the present invention is not limited to the specific embodiments.

[0042] Unless otherwise expressly stated, throughout the specification and claims, the term "comprising" or its variations such as "including" or "comprises" shall be understood to include the stated elements or components without excluding other elements or other components.

[0043] like Figures 1 to 2 As shown, a cylinder position switch sensor according to a preferred embodiment of the present invention achieves efficient filtering of stray magnetic fields at the hardware level through multi-channel magnetic field collaborative sensing and logic gates. It has excellent anti-electromagnetic interference performance, can effectively eliminate the detection misjudgment and missed judgment problems caused by the different sizes of magnetic rings inside the cylinder, significantly improve the accuracy of magnetic field determination and the overall operational stability of the equipment, and can be adapted to various specifications and types of cylinders.

[0044] Specifically, Figure 1 The diagram shown is a structural schematic of a cylinder position switch sensor. Figure 2 This is the circuit diagram for the cylinder position switch sensor. (Combined with...) Figure 1 and Figure 2 As shown, the cylinder position switch sensor includes a magnetic sensing unit, an axial signal processing unit, a radial signal processing unit, a logic gate unit, and a drive unit. The magnetic sensing unit can be fixedly installed outside the cylinder and is configured to detect the axial and radial magnetic flux generated when the cylinder piston moves axially, converting the axial and radial magnetic flux into corresponding axial and radial electrical signals, respectively. The cylinder described here has a permanent magnet (i.e., a magnetic ring) inside its piston. As the piston reciprocates along the cylinder axis, the permanent magnet synchronously generates changing axial and radial magnetic fields, and the magnetic sensing unit can collect the magnetic flux corresponding to these magnetic fields in real time. Meanwhile, the axial and radial electrical signals mentioned here can be continuously changing analog voltage signals; this invention is not limited to this.

[0045] The axial signal processing unit is connected to the output of the magnetic sensing unit and can be used to determine whether the magnetic field strength meets the standard. In specific implementations, the axial signal processing unit is configured to determine whether the axial electrical signal meets a preset condition compared to a reference signal. If the preset condition is met, it outputs a valid signal (e.g., a high-level signal), indicating that the magnetic field strength meets the standard; if the preset condition is not met, it outputs an invalid signal (e.g., a low-level signal), indicating that the magnetic field strength does not meet the standard. The preset condition can be flexibly configured according to the actual application scenario. For example, the preset condition can be set to the axial electrical signal being greater than the reference signal. That is, when the axial electrical signal is greater than the reference signal, the preset condition is met, and a valid signal is output; when the axial electrical signal is less than the reference signal, the preset condition is not met, and an invalid signal is output. In practical applications, by setting a corresponding reference signal, the axial signal processing unit can adapt to permanent magnets of different sizes and magnetic field strengths. In other words, by setting a corresponding reference signal, regardless of the size of the permanent magnet or the strength of the magnetic field, the axial signal processing unit can reliably identify and output the corresponding level signal, thus adapting to a wider range of scenarios. In this embodiment, valid signals all refer to high-level signals (logic 1), and invalid signals all refer to low-level signals (logic 0).

[0046] The radial signal processing unit is also connected to the output of the magnetic sensing unit and can be used to determine whether the current magnetic field is an effective magnetic field generated by the target permanent magnet. In specific implementations, the radial signal processing unit is configured to determine whether the radial electrical signal has crossed zero, and output a valid signal when a zero crossing occurs, i.e., confirming that the current magnetic field is an effective magnetic field generated by the target permanent magnet and there is no external stray magnetic field interference; when a zero crossing does not occur, it outputs an invalid signal, i.e., confirming that the current magnetic field is not an effective magnetic field generated by the target permanent magnet. Figure 5 As shown, zero crossing here refers to the radial electrical signal amplitude changing from positive to negative when it crosses the zero amplitude point, or from negative to positive when it crosses the zero amplitude point. When there is external stray magnetic field interference, the radial electrical signal will not cross zero. Therefore, the presence or absence of stray magnetic field interference can be determined by whether or not a zero crossing occurs.

[0047] The logic gate unit is connected to both the axial and radial signal processing units, and can determine whether the target permanent magnet is in position based on the signals output by these units. In specific implementations, it is configured to receive signals from both the axial and radial signal processing units, and output a valid signal when both units output valid signals. That is, when both the axial magnetic field magnitude meets the requirement and the radial magnetic field is an effective magnetic field generated by the target permanent magnet, the logic gate unit outputs a valid signal to determine that the target permanent magnet is in position. Conversely, if either the axial or radial signal processing unit outputs an invalid signal, it outputs an invalid signal to determine that the target permanent magnet is not in position.

[0048] The drive unit is connected to the logic gate unit and is configured to output a control signal when it receives a valid signal from the logic gate unit to control the operation of the corresponding components, such as controlling solenoid valves, LED lights, etc.

[0049] Combination Figures 1-3 As shown, during operation, the cylinder position switch sensor detects the axial and radial magnetic flux generated by the piston movement through a magnetic sensing unit. These are then converted into axial and radial electrical signals, respectively, and sent to the corresponding signal processing units. The axial signal processing unit compares the received axial electrical signal with a reference signal to determine if the axial magnetic flux meets the standard. If the axial magnetic flux meets the standard, it outputs a valid signal to the logic gate unit. The radial signal processing unit judges the received radial electrical signal to determine if a zero-crossing has occurred, thus determining if the current magnetic field is an effective magnetic field generated by the target permanent magnet. If a zero-crossing occurs, it outputs a valid signal to the logic gate unit. The logic gate unit outputs a valid signal to the drive unit only when both the axial and radial signal processing units output valid signals; otherwise, it outputs an invalid signal to the drive unit. The drive unit outputs a control signal upon receiving a valid signal to control the operation of the corresponding components.

[0050] Compared to existing technologies, this invention simultaneously acquires axial and radial magnetic flux through a magnetic sensing unit. The axial signal processing unit determines the amplitude threshold and verifies whether the axial magnetic flux intensity meets the standard, while the radial signal processing unit performs zero-crossing detection to distinguish whether the current magnetic field originates from the effective magnetic field of the target permanent magnet. The determination results from both units are input to a logic gate unit for joint verification. A control signal is only output when the axial magnetic flux meets the standard and the effective magnetic field of the target permanent magnet is detected. This allows for efficient filtering of stray magnetic fields at the hardware level, effectively avoiding false detections.

[0051] like Figure 4As shown, the magnetic sensing unit includes a power input terminal, a ground terminal, and magnetoresistors R1, R2, R3, and R4. Magnetoresistors R1 and R2 are connected in series to form the left voltage divider branch, and the connection point between them serves as the axial voltage signal output terminal Vx. The magnetic sensing direction of this left voltage divider branch is parallel to the axial movement direction of the cylinder piston rod, and it can be used to acquire the axial magnetic flux generated during piston movement in real time and convert it into a continuously changing analog axial voltage signal Vx.

[0052] Magnetoresistors R3 and R4 are connected in series to form the right-side voltage divider branch. The connection point between them serves as the radial voltage signal output terminal Vy. One end of each voltage divider branch is connected to the power supply input, and the opposite ends are connected to the ground. The magnetic sensing direction of this right-side voltage divider branch is perpendicular to the outer surface of the cylinder body and points towards the cylinder centerline. It can be used to acquire the radial magnetic flux generated during piston movement in real time and convert it into a continuously varying analog radial voltage signal Vy.

[0053] In practical implementation, when an external magnetic field, such as that from the permanent magnet inside the cylinder, approaches this circuit, the resistance of the magnetoresistors arranged diagonally in the bridge circuit changes in the opposite direction due to the influence of the magnetic field direction. This reverse resistance change alters the voltage division ratio of the left and right voltage divider branches, causing Vx to output an analog voltage signal corresponding to the axial magnetic flux and Vy to output an analog voltage signal corresponding to the radial magnetic flux. These two voltage signals can be sent to the axial signal processing unit and the radial signal processing unit, respectively, to complete threshold determination and zero-crossing detection, thereby achieving two-dimensional acquisition of the magnetic field of the cylinder piston permanent magnet.

[0054] like Figure 5 As shown, the axial signal processing unit includes a reference signal input unit and a first comparator. The reference signal input unit is configured to input a reference signal to the first comparator. The reference signal can be set to a fixed threshold or a dynamically adaptive threshold to adapt to the range of magnetic flux variation under different operating conditions. One input terminal of the first comparator is connected to a magnetic sensing unit, the other input terminal is connected to the reference signal input unit, and the output terminal is connected to a logic gate unit. It is configured to compare the axial electrical signal output by the magnetic sensing unit with the reference signal and output a valid signal or an invalid signal based on the comparison result. In this invention, the first comparator compares the axial voltage signal with the reference voltage signal. When the axial voltage signal is greater than the reference voltage signal, a valid signal is output to indicate that the magnetic flux is within the specified range and the cylinder piston has moved to the designated position; when the axial voltage signal is less than the reference voltage signal, an invalid signal is output to indicate that the magnetic flux is insufficient and the cylinder piston has not moved to the designated position.

[0055] Furthermore, such as Figure 5As shown, the reference signal input unit includes a reference voltage input terminal Vref, a voltage divider circuit (including a first voltage divider resistor R1 and a second voltage divider resistor R2), and a ground terminal GND. One end of the first voltage divider resistor R1 is connected to the reference voltage input terminal Vref, and the other end is connected to one end of the second voltage divider resistor R2. The node formed by these two connections serves as the voltage divider output terminal Vout, outputting a voltage divider reference level as a reference signal. The other end of the second voltage divider resistor R2 is connected to the ground terminal GND.

[0056] In this embodiment, the reference voltage input terminal Vref can be connected to reference voltages of different amplitudes according to actual operating conditions. For example, one of the reference voltages Vref1 and Vref2 can be connected to the reference voltage input terminal Vref. That is, by switching the voltage source connected to the reference voltage input terminal Vref, multiple reference levels of different amplitudes can be output to adapt to magnets of different sizes and specifications. This design can effectively solve the defects of the existing technology that uses a single fixed reference voltage, resulting in a narrow adaptation range and the need for repeated adjustment of the range for multiple product specifications. In the specific implementation process, a low dropout linear regulator (LDO) can be used to build a multi-channel regulated output circuit to generate multiple stable reference voltages with different amplitudes, which can be used as optional reference sources for circuit switching.

[0057] Furthermore, such as Figure 3 As shown, the axial signal processing unit further includes a signal amplification unit connected between the magnetic sensing unit and the first comparator, configured to amplify the axial electrical signal. This signal amplification unit includes, but is not limited to, an amplifier.

[0058] like Figure 5 As shown, the radial signal processing unit includes a reference signal input unit and a second comparator. The reference signal input unit is configured to input a reference signal to the second comparator. One input terminal of the second comparator is connected to a magnetic sensing unit, the other input terminal is connected to the reference signal input unit, and the output terminal is connected to a logic gate unit. It is configured to determine whether the radial electrical signal has crossed zero and output a valid signal or an invalid signal based on the determination result. Here, the second comparator compares the radial electrical signal with the reference signal to determine whether a zero crossing has occurred based on the comparison result. The reference signal is a zero magnetic field voltage signal. In this invention, when the radial electrical signal crosses zero, the comparator outputs a valid signal to the logic gate unit to indicate that the current magnetic field is an effective magnetic field generated by the target permanent magnet; when the radial electrical signal does not cross zero, the comparator outputs an invalid signal to the logic gate unit to indicate that there is ambient stray magnetism present, and it is not an effective magnetic field generated by the target magnet.

[0059] Furthermore, such as Figure 5As shown, the reference signal input unit includes a reference voltage input terminal Vcc, voltage divider resistors R3 and R4, and a ground terminal GND. One end of voltage divider resistor R3 is connected to the reference voltage input terminal Vcc, and the other end is connected to one end of voltage divider resistor R4. The node formed by the two connected ends serves as the voltage divider output terminal, outputting a voltage divider reference level. The other end of voltage divider resistor R4 is connected to the ground terminal GND.

[0060] Furthermore, as shown in the figure, the radial signal processing unit also includes a signal amplification unit connected between the magnetic sensing unit and the second comparator, which is configured to amplify the radial electrical signal. This signal amplification unit includes, but is not limited to, an amplifier.

[0061] like Figure 2 As shown, the logic gate unit includes an AND gate, whose two inputs are connected to the axial signal processing unit and the radial signal processing unit, respectively, and whose output is connected to the drive unit. The AND gate can output a valid signal when both the axial and radial signal processing units receive valid inputs. In other words, it requires the simultaneous fulfillment of the output conditions of a axial magnetic field reaching the specified magnitude and a radial magnetic field crossing zero to output a valid high level. At this point, it is determined that the target permanent magnet is in position, and a valid control signal is output. If either axis does not meet the conditions, such as an axial valid state and a radial invalid state, the AND gate will block the output and will not output a valid control signal. In the case of an axial invalid state and a radial valid state, the AND gate will have no output, as the magnet is too far away and no valid control signal is output. The pure hardware AND gate logic can perfectly filter out stray magnetic fields and multi-peak interference, providing great convenience for operators and market users, reducing troubleshooting, and significantly shortening the time spent ineffective operation.

[0062] like Figure 2 As shown, the driving unit includes a power transistor driver, a first transistor, and a second transistor. The first and second transistors are connected in series between the power supply and ground, and the common node formed by their series connection constitutes the output terminal Vout. The gates of the first and second transistors are interconnected and connected to the output terminal of the power transistor driver. The first and second transistors are different types of power devices. The input terminal of the power transistor driver is connected to a logic gate unit. The power transistor driver can output a drive signal when the logic gate unit outputs a valid signal to control the selective conduction of either the first or second transistor.

[0063] In this embodiment, it is optimal to use a PMOS transistor as the first transistor and an NMOS transistor as the second transistor.

[0064] Furthermore, the driving unit also includes a driving mode selection input terminal, which is electrically connected to the power transistor driver; this input terminal is configured to receive an externally input driving mode selection signal. The power transistor driver can output a corresponding driving level according to the received driving mode selection signal, thereby controlling one of the first transistor and the second transistor to selectively conduct.

[0065] In the specific implementation process, an external control level can be input to the drive mode selection input terminal. The power transistor driver switches the internal push-pull topology of the drive unit according to the high or low state of the external level, so that the drive unit works in NPN pull-down output mode or PNP pull-up output mode.

[0066] In this embodiment, the drive mode selection input terminal can be used with a normally open contact (NO) or a normally closed contact (NC) to achieve external mode switching control.

[0067] like Figure 2 As shown, the driving unit also includes a delay unit connected between the logic gate unit and the power transistor driver. This delay unit is configured to delay the signal output from the logic gate unit. The delay unit includes a constant current source (not shown) connected to a delay function pin (Delay pin), which can be used to connect an adjustable-size passive timing capacitor. The constant current source can charge the passive timing capacitor. The driving unit can acquire the voltage across the timing capacitor in real time, and output a delay control signal when the voltage reaches a preset threshold.

[0068] like Figure 2 As shown, the driving unit also includes an LED driving unit, which is configured to drive the LED lamp to emit light.

[0069] like Figure 2 As shown, the drive unit also includes an overcurrent protection unit, through which the second transistor is grounded. The overcurrent protection unit includes a sampling resistor and an overcurrent protection module. One end of the sampling resistor is connected to the second transistor to form a sampling node, and the other end is grounded. The overcurrent protection module (OCP) is connected to the sampling node and can acquire the voltage signal across the sampling resistor in real time. In a specific implementation, the current flowing out of the second transistor flows through the sampling resistor Rs, generating a sampling voltage across Rs. The overcurrent protection module continuously acquires this sampling voltage and triggers protection when the sampling voltage exceeds a preset threshold. The OCP module further outputs a protection control signal to control the transistor to turn off or limit the output current, thus achieving the overcurrent protection function.

[0070] This invention uses dual-axis magnetic field sampling combined with hardware AND gate logic for signal filtering. It relies on hardware circuits to perform real-time filtering calculations of spatial stray magnetic fields, achieving rapid filtering of hardware-level stray interference. It can effectively shield the spatial stray magnetic fields brought by the equipment cylinder and surrounding electromagnetic devices, avoid stray signals interfering with the effective signals of the magnets, significantly improve the accuracy of magnetic signal recognition, and has significantly better anti-interference capabilities than software filtering schemes.

[0071] Meanwhile, the present invention is a pure hardware signal processing architecture. It uses an operational amplifier to replace the ADC analog-to-digital converter chip and microcontroller control unit in the traditional solution, eliminating the faulty links such as software program, clock timing, and digital communication. It eliminates the hidden dangers of program crashes, system crashes, and software logic anomalies. The circuit link is simple, and the working stability is stronger under high and low temperature and complex working conditions, and the equipment failure rate is greatly reduced.

[0072] This invention also allows for the setting of a switchable external reference voltage scheme, which can match the corresponding reference level according to the magnetic field output characteristics of magnets of different sizes and materials. There is no need to replace the detection motherboard or modify the software parameters. It can adapt to various magnet products simply by switching the reference level, which greatly simplifies the on-site whole machine debugging process and has a wider range of compatibility.

[0073] The foregoing description of specific exemplary embodiments of the invention is for illustrative and explanatory purposes. These descriptions are not intended to limit the invention to the precise forms disclosed, and it will be apparent that many changes and variations can be made in accordance with the foregoing teachings. The exemplary embodiments were chosen and described in order to explain the specific principles of the invention and its practical application, thereby enabling those skilled in the art to implement and utilize various different exemplary embodiments of the invention, as well as various different choices and variations. The scope of the invention is intended to be defined by the claims and their equivalents.

Claims

1. A cylinder position switch sensor, characterized in that, include: The magnetic sensing unit is configured to detect the axial magnetic flux and radial magnetic flux generated when the cylinder piston moves, and convert the axial magnetic flux and radial magnetic flux into axial electrical signals and radial electrical signals, respectively. An axial signal processing unit, connected to the magnetic sensing unit, is configured to determine whether the axial electrical signal meets a preset condition compared with a reference signal, and output a valid signal when the preset condition is met, and output an invalid signal when the preset condition is not met. A radial signal processing unit, connected to the magnetic sensing unit, is configured to determine whether the radial electrical signal has crossed zero, and output a valid signal when it has crossed zero, and output an invalid signal when it has not crossed zero. The logic gate unit is connected to both the axial signal processing unit and the radial signal processing unit, and is configured to output a valid signal when both the axial signal processing unit and the radial signal processing unit output valid signals. The driving unit, connected to the logic gate unit, is configured to output a control signal when a valid signal is received from the logic gate unit.

2. The cylinder position switch sensor as described in claim 1, characterized in that, The axial signal processing unit includes The reference signal input unit is configured to input a reference signal; The first comparator has one input connected to a magnetic sensing unit, another input connected to a reference signal input unit, and an output connected to a logic gate unit. It is configured to compare an axial signal with a reference signal and output a valid signal when the axial signal is greater than the reference signal and an invalid signal when the axial signal is less than the reference signal.

3. The cylinder position switch sensor as described in claim 2, characterized in that, The reference signal input unit includes a reference voltage input terminal and a voltage divider circuit. The voltage divider circuit is connected between the reference voltage input terminal and the input terminal of the first comparator. The reference voltage input terminal can be connected to reference voltages of different magnitudes.

4. The cylinder position switch sensor as described in claim 3, characterized in that, The reference voltage input can be selectively connected to any one of multiple reference voltages, which are output via a low-dropout linear regulator.

5. The cylinder position switch sensor as described in claim 1, characterized in that, The radial signal processing unit includes The reference signal input unit is configured to input a reference signal; The second comparator has one input connected to a magnetic sensing unit, another input connected to a reference signal input unit, and an output connected to a logic gate unit. It is configured to compare a radial signal with a reference signal and output a valid signal when the two match. The reference signal is a zero magnetic field voltage signal.

6. The cylinder position switch sensor as described in claim 1, characterized in that, The logic gate unit includes An AND gate, wherein the two input terminals of the AND gate are respectively connected to an axial signal processing unit and a radial signal processing unit, is configured to output a valid signal when both the axial signal processing unit and the radial signal processing unit output valid signals.

7. The cylinder position switch sensor as described in claim 1, characterized in that, The drive unit includes The first transistor and the second transistor are connected in series between the power supply and ground. The common node formed by their series connection forms the control signal output terminal. The gates of the first transistor and the second transistor are interconnected and further connected to the output terminal of the power transistor driver. The power transistor driver has its input connected to a logic gate unit and is configured to output a drive signal when the logic gate unit outputs a valid signal, so as to control one of the first transistor and the second transistor to conduct.

8. The cylinder position switch sensor as described in claim 1, characterized in that, The drive unit also includes The drive mode selection input terminal is connected to the power transistor driver and is configured to receive an externally input drive mode selection signal so that the power transistor driver outputs a corresponding drive level according to the received drive mode selection signal, thereby controlling the first transistor and the second transistor to selectively conduct.

9. The cylinder position switch sensor as described in claim 1, characterized in that, The drive unit includes The delay unit includes a constant current source and a delay function pin connected to the constant current source. The delay function pin can be connected to a passive timing capacitor with an adjustable size. The constant current source is configured to charge the passive timing capacitor. The driving unit can collect the voltage across the timing capacitor in real time and output a control signal when the voltage reaches a preset threshold.

10. The cylinder position switch sensor as described in claim 7, characterized in that, The driving unit further includes an overcurrent protection unit, wherein the second transistor is grounded through the overcurrent protection unit, and the overcurrent protection unit includes... A sampling resistor, one end of which is connected to the second transistor to form a sampling node, and the other end is grounded; The overcurrent protection module, connected to the sampling node, is configured to acquire the voltage signal across the sampling resistor in real time and trigger protection when the sampling voltage exceeds a preset threshold.

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