Displacement sensor and hydraulic cylinder

Abstract

This invention relates to the field of hydraulic technology, and more particularly to a displacement sensor and a hydraulic cylinder. The displacement sensor, disposed at one end of the hydraulic cylinder, includes: a speed measuring probe, whose transmitting and receiving wave direction is towards a reference element, for real-time measurement of the current wave velocity in the hydraulic medium within the hydraulic cylinder; and a distance measuring probe, whose transmitting and receiving wave direction is perpendicular to the piston end face of the hydraulic cylinder. A channel for hydraulic medium communication is provided between the displacement sensor and the hydraulic cylinder on the outer sides of the speed measuring probe and the distance measuring probe, so that the speed measuring probe and the distance measuring probe are under the same hydraulic medium operating conditions. The speed measuring probe calculates the current wave velocity by detecting a reference element at a fixed distance, and the distance measuring probe calculates the real-time distance between the piston rod and the distance measuring probe based on the measured current wave velocity by recording the time difference between wave transmission and reception.

Description

Technical Field

[0001] This invention relates to the field of hydraulic technology, and more particularly to a displacement sensor and a hydraulic cylinder. Background Technology

[0002] In modern industrial applications, hydraulic systems are widely used in various types of machinery and equipment due to their high efficiency and precision. As one of the core components, the performance of the hydraulic cylinder directly affects the operating efficiency and stability of the entire system, while accurate detection of piston displacement is a key factor in ensuring the normal operation of the hydraulic system.

[0003] Currently, hydraulic cylinder piston displacement detection mainly relies on contact sensors, such as magnetostrictive sensors. However, these sensors have some significant drawbacks: their large size requires extensive machining of the piston rod during installation, increasing manufacturing costs and process complexity; considering that hydraulic cylinders typically employ welded structures, sensor replacement is complex and difficult once damaged, increasing maintenance costs and potentially impacting production efficiency. Furthermore, contact sensors are generally more expensive than non-contact sensors.

[0004] Especially in mining equipment applications, magnetostrictive sensors are frequently used to measure the stroke of mining hydraulic cylinders. While these sensors can provide relatively accurate displacement data, their large footprint and complex structure make it difficult to create an effective hollow wiring channel within a limited space, causing inconvenience in the machining and installation of the hydraulic cylinder. Furthermore, different physical states of the liquid medium (such as changes in temperature and density) affect the propagation speed of ultrasonic and millimeter waves in the medium, creating obstacles for non-contact hydraulic cylinder stroke measurement. Summary of the Invention

[0005] This invention provides a displacement sensor and a hydraulic cylinder to address the shortcomings of existing contact sensors, such as large size, complex installation, difficult replacement, and high cost, thereby achieving high-precision, easy-to-install and maintain, and more cost-effective piston displacement detection.

[0006] This invention provides a displacement sensor disposed at one end of a hydraulic cylinder, comprising: a speed measuring probe, the transmission and reception direction of which is oriented toward a reference element, for real-time measurement of the current wave velocity in the hydraulic medium within the hydraulic cylinder; and a distance measuring probe, the transmission and reception direction of which is perpendicular to the piston end face of the hydraulic cylinder. A channel for communication of the hydraulic medium is provided between the displacement sensor and the hydraulic cylinder on the outer sides of the speed measuring probe and the distance measuring probe, so that the speed measuring probe and the distance measuring probe are under the same hydraulic medium operating conditions.

[0007] According to one embodiment of the present invention, an anti-rotation structure is further included, which is installed between the cylinder body of the hydraulic cylinder and the ranging probe, for preventing the ranging probe of the displacement sensor from moving or rotating due to hydraulic shock or hydrodynamic force.

[0008] According to one embodiment of the present invention, the speed measuring probe is provided with a first pressure-resistant housing, which is made of ceramic, polyetheretherketone, aluminum alloy or carbon fiber, and the transmission frequency of the speed measuring probe is above 50 kHz; the ranging probe is provided with a second pressure-resistant housing, which is made of ceramic, polyetheretherketone, aluminum alloy or carbon fiber, and the transmission frequency of the ranging probe is above 50 kHz; the transmission frequency of the speed measuring probe is higher than the transmission frequency of the ranging probe.

[0009] According to one embodiment of the present invention, the displacement sensor is provided with dual digital communication interfaces that support serial communication mode for data interaction and control signal transmission among multiple sensors.

[0010] According to one embodiment of the present invention, the installation position of the ranging probe satisfies one of the following conditions: the center of the emission hole coincides with the axis of the hydraulic cylinder; the emission hole is arranged parallel to the axis of the hydraulic cylinder at other preset positions.

[0011] According to one embodiment of the present invention, on the outside of the reference member, the displacement sensor further includes a one-way valve; the one-way valve has a pre-pressure of 0.5 MPa and is used to release pressure during the reciprocating motion of the hydraulic cylinder to avoid the risk of pressure buildup.

[0012] According to one embodiment of the present invention, the displacement sensor is configured such that: the velocity probe detects the reference element at a fixed distance L1, records the time difference t1 between wave transmission and wave reception, and calculates the current wave velocity v1 = 2L1 / t1; the distance measuring probe, based on the measured current wave velocity v1, calculates the real-time distance L2 = v1t2 / 2 between the piston rod and the distance measuring probe by recording the time difference t2 between wave transmission and wave reception.

[0013] The present invention also provides a hydraulic cylinder, comprising: a hydraulic cylinder body; a displacement sensor according to the above embodiments, the displacement sensor being radially mounted on the hydraulic cylinder body; the displacement sensor measuring the current wave velocity in the hydraulic medium in real time through a speed measuring probe, and dynamically compensating the displacement measurement value of the piston rod based on the wave velocity through a distance measuring probe; a sealing structure is respectively provided on the upper and lower sides of the distance measuring probe between the displacement sensor and the mounting hole of the hydraulic cylinder body, and the sealing area is consistent to achieve hydraulic pressure balance.

[0014] According to one embodiment of the present invention, the hydraulic cylinder is a single-stage hydraulic cylinder, and the displacement sensor directly monitors the displacement of the piston rod of the hydraulic cylinder.

[0015] According to one embodiment of the present invention, the hydraulic cylinder is a multi-stage hydraulic cylinder, the multi-stage hydraulic cylinder comprising: a first-stage cylinder body; a second-stage cylinder body slidably disposed within the first-stage cylinder body, and the second-stage cylinder body being provided with a bottom valve, the bottom valve being used to prevent hydraulic medium from entering the second-stage cylinder body before the second-stage cylinder body is fully extended from the first-stage cylinder body; and a third-stage cylinder body slidably disposed within the second-stage cylinder body.

[0016] The displacement sensor and hydraulic cylinder provided by this invention achieve high-precision detection of piston displacement through a speed measuring probe and a distance measuring probe installed at one end of the hydraulic cylinder. The speed measuring probe faces the reference component and measures the current wave velocity in the hydraulic medium in real time, while the distance measuring probe faces the rodless cavity and dynamically measures the displacement of the piston rod based on the measured wave velocity. Both probes operate under the same hydraulic medium conditions and achieve distance measurement accuracy compensation through data interaction. Compared with existing contact sensors, this invention eliminates the need for extensive processing of the piston rod, greatly simplifying the installation process and avoiding the replacement difficulties caused by welded structures, making maintenance more convenient. Furthermore, the non-contact measurement method not only reduces the size and complexity of the equipment but also lowers costs, achieving a more economical and efficient solution. Therefore, this invention effectively overcomes the problems of large size, complex installation, difficult replacement, and high cost of traditional contact sensors, providing a precise, easy-to-install and maintain, and more cost-effective new approach for hydraulic cylinder piston displacement detection. Attached Figure Description

[0017] To more clearly illustrate the technical solutions in this invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0018] Figure 1 This is a schematic diagram of the assembly structure of the displacement sensor provided by the present invention.

[0019] Figure 2 This is a schematic flowchart of the accuracy compensation and ranging process of the displacement sensor provided by the present invention.

[0020] Figure 3 This is one of the structural schematic diagrams of the hydraulic cylinder provided by the present invention.

[0021] Figure 4 This is the second schematic diagram of the hydraulic cylinder provided by the present invention.

[0022] Figure 5This is a schematic diagram of the multi-radar sensor digital communication serial application of the displacement sensor provided by the present invention.

[0023] Figure 6 This is a schematic diagram of the anti-rotation structure of the displacement sensor provided by the present invention.

[0024] Figure label: 11. Speed ​​probe; 12. Reference component; 13. Distance probe; 14. Anti-rotation structure; 15. Dual digital communication interface; 16. Check valve; 20. Hydraulic cylinder body; 21. Rodless chamber; 22. Piston rod; 23. First-stage cylinder; 24. Second-stage cylinder; 25. Bottom valve; 26. Third-stage cylinder. Detailed Implementation

[0025] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this invention. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0026] In the description of the embodiments of the present invention, it should be noted that the terms "center," "longitudinal," "lateral," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," and "outer," etc., indicating the orientation or positional relationship, are based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing the embodiments of the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the embodiments of the present invention. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance. It should also be noted that in the description of the present invention, unless otherwise explicitly specified and limited, the terms "set," "install," and "connect" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection. Those skilled in the art can understand the specific meaning of the above terms in the present invention according to the specific circumstances.

[0027] This invention proposes a displacement sensor for mining hydraulic cylinders, designed to accurately measure the position of the piston rod. The sensor employs a dual-probe method combining a velocity probe and a distance probe. By real-time measurement of the wave velocity of the medium within the hydraulic cylinder and the resulting dynamic displacement measurement, high-precision detection of the piston rod position is achieved.

[0028] The following is combined Figures 1-6This invention describes specific embodiments of the displacement sensor and hydraulic cylinder of the present invention.

[0029] like Figure 1 As shown, the present invention provides a displacement sensor, disposed at one end of a hydraulic cylinder, comprising: a speed measuring probe 11, the transmission and reception direction of the speed measuring probe 11 being oriented toward a reference member 12, used to measure in real time the current wave velocity in the hydraulic medium within the hydraulic cylinder, the current wave velocity being the transmission speed of ultrasonic waves or millimeter waves in the hydraulic medium; and a distance measuring probe 13, the transmission and reception direction of the distance measuring probe 13 being perpendicular to the piston end face 21 of the hydraulic cylinder. A channel for communication of the hydraulic medium is provided between the displacement sensor and the hydraulic cylinder on the outer side of the speed measuring probe 11 and the distance measuring probe 13, so that the speed measuring probe 11 and the distance measuring probe 13 are under the same hydraulic medium operating conditions.

[0030] Specifically, the displacement sensor accurately measures the wave velocity change in the hydraulic medium through the velocity probe 11 and corrects for the effects of different physical conditions (such as temperature and density changes) on the propagation speed of ultrasonic or millimeter waves. This step ensures accurate acquisition of the current wave velocity even under changing operating conditions. The ranging probe 13 uses the corrected wave velocity information to calculate the real-time position of the piston rod 22, ensuring high measurement accuracy. The integrated design of the dual probes allows the sensor to be directly installed on one end of the hydraulic cylinder without modifying its original structure, simplifying the installation process and enhancing the overall reliability of the system.

[0031] In practical applications, this displacement sensor can monitor changes in the internal environment of the hydraulic cylinder in real time without affecting its normal operation, and dynamically adjust the measurement parameters accordingly to ensure data accuracy. Employing a non-contact measurement method avoids errors caused by mechanical wear and the complex replacement process of traditional contact sensors, thus improving long-term stability and economic efficiency. By integrating speed and distance measurement functions into a single device, this invention provides a more efficient, reliable, and easy-to-maintain solution for hydraulic cylinder piston displacement detection.

[0032] Furthermore, the radar sensor in this invention preferably integrates a temperature detection circuit, a boost excitation pulse circuit, a signal amplification and shaping circuit, a processor, and the aforementioned dual-transmitter / receiver probes. This sensor employs a dual-transmitter / receiver probe design for both speed and distance measurement, relying on its flow channel design to ensure that both probes are in the same medium. Specifically, the speed probe 11 is used to determine the propagation speed of millimeter waves or ultrasonic waves in the current hydraulic medium, and the distance probe 13 is used to measure the position of the piston rod 22 in real time.

[0033] The displacement sensor provided by this invention employs a dual-probe design, including a velocity-measuring probe 11 and a distance-measuring probe 13. It aims to achieve accurate and stable measurement of the displacement of the hydraulic cylinder piston rod 22. It not only considers the influence of different working conditions on the physical state of the hydraulic medium (such as temperature, pressure, and concentration), but also proposes a method for real-time compensation of wave velocity changes to ensure high-precision measurement. The displacement sensor is configured as follows: the velocity-measuring probe 11 calculates the current wave velocity by detecting a reference element 12 at a fixed distance; the distance-measuring probe 13 calculates the real-time distance between the piston rod 22 and the distance-measuring probe 13 based on the measured current wave velocity by recording the time difference between wave emission and reception.

[0034] Specifically, the speed probe 11 emits millimeter-wave or ultrasonic signals to the reference element 12 and receives the reflected signals. By recording the time difference t1 between the emission and reception, and combining this with the known fixed distance L1 (i.e., the distance from the reference element 12 to the speed probe 11), the wave velocity v1 = 2L1 / t1 in the current hydraulic medium is calculated in real time. Next, the distance probe 13 uses the same principle to emit a signal towards the rodless chamber 21 of the hydraulic cylinder and receives the signal reflected back from the surface of the piston rod 22. By recording the time difference t2 of this process, and using the current wave velocity v1 previously measured by the speed probe 11, the real-time distance L2 = v1t2 / 2 of the piston rod 22 relative to the distance probe 13 can be accurately calculated. This method ensures that even when the physical state of the hydraulic medium changes under different operating conditions (such as changes in temperature and pressure causing changes in wave velocity), the measurement results can be dynamically corrected, guaranteeing the accuracy of the piston rod 22 displacement measurement.

[0035] To further improve measurement accuracy, the transmitting and receiving directions of the dual probes are preferably installed perpendicular to each other, and the sensor is connected to the hydraulic cylinder through a channel to ensure that the liquid medium propagated by the speed measuring probe 11 and the distance measuring probe 13 is under the same operating conditions. Furthermore, a sealing structure with consistent sealing area is provided between the mounting holes of the displacement sensor and the hydraulic cylinder body 20 to achieve hydraulic pressure balance and avoid measurement errors caused by hydraulic imbalance. This dual-probe collaborative operation not only compensates for measurement errors caused by changes in the medium state but also provides high-precision position feedback in practical applications. This system allows for automatic adaptation to different working environments without manual calibration, thereby improving system reliability and ease of use. Therefore, the displacement sensor provided by this invention is particularly suitable for complex industrial applications requiring high-precision control, significantly improving the accuracy and economy of hydraulic cylinder piston displacement detection.

[0036] like Figure 1 and Figure 6As shown, a displacement sensor according to the present invention further includes an anti-rotation structure 14, installed between the cylinder body of the hydraulic cylinder and the ranging probe 13, for preventing the ranging probe 13 of the displacement sensor from moving or rotating due to hydraulic shock or hydrodynamic force. Specifically, the anti-rotation structure 14 is designed to ensure that the ranging probe 13 remains stable during the reciprocating extension and retraction of the hydraulic cylinder, avoiding probe rotation problems caused by hydrodynamic force. This anti-rotation structure 14 can effectively ensure the perpendicularity between the ranging probe 13 and the piston rod 22 of the hydraulic cylinder, maintaining its position even under hydraulic shock, thereby ensuring that the measurement accuracy is not affected.

[0037] In addition to the anti-rotation structure 14 in the form of an anti-rotation cover plate shown in the figure, other traditional anti-rotation structures 14, such as pin connections and snap rings, are also included in the protection scope. They can also prevent the probe from rotating, ensuring the stability and reliability of the entire sensor system.

[0038] According to a displacement sensor of the present invention, a speed measuring probe 11 is provided with a first pressure-resistant housing, which is made of ceramic, polyetheretherketone, aluminum alloy or carbon fiber, and the transmission frequency of the speed measuring probe 11 is above 50 kHz; a distance measuring probe 13 is provided with a second pressure-resistant housing, which is made of ceramic, polyetheretherketone, aluminum alloy or carbon fiber, and the transmission frequency of the distance measuring probe 13 is above 50 kHz; the transmission frequency of the speed measuring probe 11 is higher than the transmission frequency of the distance measuring probe 13.

[0039] Specifically, the speed measuring probe 11 has a transmission frequency higher than 50 kHz, and its transmission frequency is higher than that of the distance measuring probe 13. Both probes operate using high-frequency signals, with a frequency range above 50 kHz. Using such high-frequency signals helps improve measurement resolution and accuracy, especially providing finer distance resolution in hydraulic media, thereby enabling precise measurement of the displacement of the piston rod 22. Because high-frequency signals effectively reduce the influence of external interference and noise, this ensures the accuracy and reliability of the data.

[0040] Furthermore, by setting the transmission frequency of the velocity sensor 11 to be higher than that of the distance measuring sensor 13, the performance of the entire system can be further optimized. The higher frequency allows the velocity sensor 11 to more accurately determine the current wave velocity, providing a basis for subsequent high-precision distance measurements performed by the distance measuring sensor 13, thereby improving the accuracy and stability of the overall displacement detection. This configuration is particularly suitable for hydraulic systems that need to operate in complex and variable environments, ensuring a high level of measurement accuracy and reliability even under adverse conditions.

[0041] like Figure 5As shown, according to a displacement sensor of the present invention, the displacement sensor is provided with a dual digital communication interface 15 supporting a serial communication mode for data interaction and control signal transmission between multiple sensors. Specifically, this dual digital communication interface design allows the displacement sensor to be connected in series with other similar sensors to form an efficient data communication network. This design not only simplifies the complexity of integrating multiple sensors into existing systems but also improves the reliability and efficiency of data transmission, enabling seamless collaboration between the sensors. Sensors using dual digital communication channels can achieve efficient serial communication. In serial communication mode, not only can wiring complexity and cost be reduced, but the scalability of the system can also be enhanced, facilitating future upgrades and maintenance. It is understood that although the present invention emphasizes the advantages of the dual digital communication interface 15, single-channel digital communication and analog communication methods are also within the scope of protection of the present invention.

[0042] According to a displacement sensor of the present invention, the installation position of the ranging probe 13 satisfies one of the following conditions: the center of the emission port coincides with the axis of the hydraulic cylinder; or the emission port is arranged parallel to the axis of the hydraulic cylinder at another predetermined position. Specifically, aligning the center of the emission port with the axis of the hydraulic cylinder is the ideal choice, as this arrangement maximizes measurement accuracy and stability, ensuring that the signal emitted by the ranging probe 13 reaches the target position most directly and effectively, and reducing errors caused by angular deviations. However, in practical applications, considering installation space limitations, structural design requirements, or other factors, the emission port can also be arranged parallel to the axis of the hydraulic cylinder at other predetermined positions. Sufficient measurement accuracy can still be guaranteed through appropriate calibration and compensation algorithms.

[0043] like Figure 1 As shown, the reference component 12 is preferably configured as a plug structure located at the bottom of the displacement sensor. A sealing structure, such as a sealing ring, can be provided around the reference component 12 of the plug structure to achieve a sealed fit between the bottom of the displacement sensor and its mounting hole. According to a displacement sensor of the present invention, a one-way valve 16 is preferably also included on the outside of the reference component 12; the one-way valve 16 has a pre-pressure of 0.5 MPa and is used to release pressure during the reciprocating motion of the hydraulic cylinder to avoid the risk of pressure buildup. Specifically, in order to prevent the gas in the hydraulic cylinder from interfering with the ranging of the radar sensor, this design removes the sealing ring at the bottom of the probe pressure housing and relies on the 0.5 MPa pre-pressure provided by the bottom one-way valve 16 to cause the hydraulic cylinder to expel internal gas during the reciprocating extension and retraction process. This mechanism ensures that the hydraulic medium can effectively remove air bubbles, thereby ensuring that the measurement accuracy of the radar sensor is not affected by gas.

[0044] Furthermore, when the sealing ring at the bottom of the probe's pressure-resistant housing is damaged, the high-pressure liquid can be safely released through the one-way valve 16, preventing equipment damage or measurement errors due to pressure buildup. This not only ensures operational safety but also extends the equipment's service life. In this way, the present invention effectively solves the problem of inaccurate measurements caused by residual gas in the hydraulic cylinder, while providing additional safety measures to deal with emergencies, enhancing the reliability and stability of the entire system.

[0045] The displacement sensor according to a preferred embodiment of the present invention has the following specific accuracy compensation ranging process: Figure 2 As shown. First, the velocity sensor 11 and the distance sensor 13 start operating simultaneously, emitting ultrasonic signals to their respective reference targets and beginning timing. To avoid interference from ultrasonic oscillations after emission, the system delays for 1 millisecond before continuing operation. Next, the velocity sensor 11 emits a signal to a reference device 12 at a fixed distance and records the time difference between emission and reception of the reflected signal. Based on this time difference and the known fixed distance, the velocity of sound in the medium is calculated. Simultaneously, the distance sensor 13 emits a signal to the surface of the piston rod 22 and records the time difference between emission and reception of the reflected signal. Subsequently, using the previously calculated velocity of sound and the time difference recorded by the distance sensor 13, the real-time position of the piston rod 22 is calculated using a specific formula. Finally, the displacement sensor outputs this real-time position data, completing a precise position measurement process. This process ensures high-precision position measurement results by dynamically compensating for errors caused by changes in the state of the hydraulic medium.

[0046] This invention also proposes a hydraulic cylinder for mining applications, incorporating sensors with displacement and pressure detection functions to measure the position of the piston rod 22 in real time and monitor the pressure in the rodless chamber 21 in real time. It possesses significant advantages such as compact structure and convenient processing and installation, and can be used with hydraulic cylinders for media such as gas, water, and oil. Preferably, it can achieve measurements from 0-5000 mm with millimeter-level accuracy. The hydraulic cylinder provided by this invention is described below, and the hydraulic cylinder described below corresponds to the displacement sensor described above.

[0047] like Figure 3As shown, the hydraulic cylinder provided by the present invention includes: a hydraulic cylinder body 20; a displacement sensor as described in the above embodiment, the displacement sensor being radially mounted on the hydraulic cylinder body 20; the displacement sensor measures the current wave velocity in the hydraulic medium in real time through a speed measuring probe 11, and dynamically compensates for the displacement measurement value of the piston rod 22 based on the wave velocity through a distance measuring probe 13; sealing structures are respectively provided on the upper and lower sides of the distance measuring probe 13 between the displacement sensor and the mounting hole of the hydraulic cylinder body 20, and the sealing areas are consistent to achieve hydraulic pressure balance. This displacement sensor, radially mounted on the hydraulic cylinder body 20, is used to monitor the position of the piston rod 22 in real time, and adjusts the extension and retraction position of the hydraulic cylinder by combining with bracket control and a reversing valve to ensure positional accuracy. This design allows the displacement sensor to achieve high-precision detection of the piston rod 22 position without interfering with the normal operation of the hydraulic cylinder.

[0048] Specifically, the displacement sensor measures the current wave velocity in the hydraulic medium in real time via the speed probe 11. The speed probe 11 calculates the current wave velocity in the hydraulic medium by transmitting a signal to a fixed-distance reference element (such as reference element 12) and receiving the reflected signal. Based on this wave velocity information, the distance measuring probe 13 records the time difference between wave transmission and reception, dynamically correcting the actual displacement value of the piston rod 22 to ensure high-precision measurement even under different operating conditions. This not only improves the accuracy of the position control of the hydraulic cylinder piston rod 22 but also enhances the stability and reliability of the system, making it suitable for various complex industrial applications.

[0049] To ensure hydraulic pressure balance and avoid measurement errors caused by hydraulic imbalance, a sealing structure is provided on the upper and lower sides of the ranging probe 13 between the displacement sensor and the mounting hole of the hydraulic cylinder body 20, and the area of ​​these sealing structures is consistent, thereby maintaining the stability of the sensor operation.

[0050] Furthermore, the preferred radial mounting method allows the displacement sensor to be easily integrated into existing hydraulic cylinders without significantly altering the original equipment structure. This not only simplifies the installation process but also reduces the mechanical wear issues that may arise from traditional contact sensors due to the use of non-contact measurement technology, further enhancing the stability and economy of long-term use.

[0051] According to a hydraulic cylinder of the present invention, the hydraulic cylinder is a single-stage hydraulic cylinder, and a displacement sensor directly monitors the displacement of the piston rod 22 of the hydraulic cylinder. Specifically, the displacement sensor is radially mounted on the hydraulic cylinder body 20, and its speed measuring probe 11 and distance measuring probe 13 work together to achieve accurate measurement of the displacement of the piston rod 22. The speed measuring probe 11 emits a signal toward the reference element 12, and calculates the wave velocity in the current hydraulic medium by analyzing the reflected signal, which is used to correct the displacement measurement performed by the distance measuring probe 13. The distance measuring probe 13 faces the rodless cavity 21 of the hydraulic cylinder, and obtains the real-time position of the piston rod 22 by emitting and receiving reflected signals on the surface of the piston rod 22 and dynamically adjusting the calculation method based on the measured wave velocity.

[0052] In addition, such as Figure 4 As shown, according to a hydraulic cylinder of the present invention, the hydraulic cylinder is a multi-stage hydraulic cylinder, comprising: a first-stage cylinder body 23; a second-stage cylinder body 24, which is slidably disposed within the first-stage cylinder body 23, and the second-stage cylinder body 24 is provided with a bottom valve 25, which is used to prevent hydraulic medium from entering the second-stage cylinder body 24 before the second-stage cylinder body 24 is fully extended from the first-stage cylinder body 23; and a third-stage cylinder body 26, which is slidably disposed within the second-stage cylinder body 24.

[0053] During the lowering and raising of the hydraulic support column, the operation of the column primarily relies on the contraction and extension of the second-stage cylinder 24, which in turn drives the third-stage cylinder 26 to perform corresponding extension and retraction movements. By using a non-contact displacement sensor to accurately detect the extension and retraction position of the second-stage cylinder 24, real-time monitoring of the dynamic position changes during the column lowering and raising process can be achieved. After the second-stage cylinder 24 is fully extended from the first-stage cylinder 23, the bottom valve 25 opens, allowing hydraulic medium to enter and push the third-stage cylinder 26 to extend further. Even in complex multi-stage hydraulic systems, the position changes of each stage cylinder can be accurately tracked, ensuring the efficient operation and stability of the entire system. The application of non-contact displacement sensors not only simplifies the installation and maintenance process but also provides reliable, high-precision position feedback, suitable for various industrial applications requiring precise control. This provides an innovative and practical technical solution for the dynamic position monitoring of multi-stage hydraulic cylinders.

[0054] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "method," "specific method," or "some methods," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or method is included in at least one embodiment or method of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or method. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or methods. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or methods described in this specification, as well as the features of different embodiments or methods.

[0055] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A displacement sensor, disposed at one end of a hydraulic cylinder, characterized in that, include: A speed measuring probe, wherein the transceiver direction of the speed measuring probe is oriented toward the reference component, is used to measure the current wave velocity in the hydraulic medium inside the hydraulic cylinder in real time; The ranging probe has its transmitting and receiving wave direction perpendicular to the piston end face of the hydraulic cylinder. A channel for hydraulic medium communication is provided between the displacement sensor and the hydraulic cylinder on the outside of the speed measuring probe and the ranging probe, so that the speed measuring probe and the ranging probe are under the same hydraulic medium operating conditions.

2. The displacement sensor according to claim 1, characterized in that, It also includes an anti-rotation structure installed between the cylinder body of the hydraulic cylinder and the ranging probe to prevent the ranging probe of the displacement sensor from moving or rotating due to hydraulic shock or hydrodynamic force.

3. The displacement sensor according to claim 1, characterized in that, The speed measuring probe is provided with a first pressure-resistant housing, which is made of ceramic, polyetheretherketone, aluminum alloy or carbon fiber, and the transmission frequency of the speed measuring probe is above 50kHz. The ranging probe is provided with a second pressure-resistant housing, which is made of ceramic, polyetheretherketone, aluminum alloy or carbon fiber, and the ranging probe has a transmission frequency range of 50kHz or higher. The transmission frequency of the speed measuring probe is higher than that of the distance measuring probe.

4. The displacement sensor according to claim 1, characterized in that, The displacement sensor is equipped with dual digital communication interfaces that support serial communication mode, which are used for data interaction and control signal transmission between multiple sensors.

5. The displacement sensor according to claim 1, characterized in that, The installation position of the ranging probe meets one of the following conditions: The center of the firing port coincides with the axis of the hydraulic cylinder; The firing port is set parallel to other preset positions on the axis of the hydraulic cylinder.

6. The displacement sensor according to claim 1, characterized in that, On the outside of the reference element, the displacement sensor also includes a one-way valve; The one-way valve has a pre-pressure of 0.5 MPa and is used to release pressure during the reciprocating motion of the hydraulic cylinder to avoid the risk of pressure buildup.

7. The displacement sensor according to any one of claims 1 to 6, characterized in that, The displacement sensor is configured as follows: The speed measuring probe detects the reference device at a fixed distance L1, records the time difference t1 between transmitting and receiving the wave, and calculates the current wave speed v1 = 2L1 / t1. The ranging probe calculates the real-time distance L2 = v1t2 / 2 between the piston rod and the ranging probe by recording the time difference t2 between transmitting and receiving the wave, based on the measured current wave velocity v1.

8. A hydraulic cylinder, characterized in that, include: Hydraulic cylinder body; The displacement sensor as described in any one of claims 1-7 is radially mounted on the hydraulic cylinder body; The displacement sensor measures the current wave velocity in the hydraulic medium in real time through a speed measuring probe, and dynamically compensates the displacement measurement value of the piston rod based on the wave velocity through a distance measuring probe. A sealing structure is provided on the upper and lower sides of the ranging probe between the displacement sensor and the mounting hole of the hydraulic cylinder body, and the sealing area is the same to achieve hydraulic pressure balance.

9. The hydraulic cylinder according to claim 8, characterized in that, The hydraulic cylinder is a single-stage hydraulic cylinder, and the displacement sensor directly monitors the displacement of the piston rod of the hydraulic cylinder.

10. The hydraulic cylinder according to claim 8, characterized in that, The hydraulic cylinder is a multi-stage hydraulic cylinder, which includes: First-stage cylinder block; The second-stage cylinder is slidably disposed within the first-stage cylinder, and the second-stage cylinder is provided with a bottom valve, which is used to prevent hydraulic medium from entering the second-stage cylinder before the second-stage cylinder is fully extended from the first-stage cylinder. The third-stage cylinder is slidably disposed within the second-stage cylinder.

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