A self-generating cutter rotating speed on-line monitoring system adaptive to a working condition of a shock

Abstract

This invention discloses a self-generating cutterhead speed online monitoring system adapted to vibration conditions. It achieves energy self-sufficiency by integrating a simplified electromagnetic self-generating structure inside the cutter shaft. Orthogonally arranged dual eddy current sensors enable synchronous detection of cutterhead speed and direction of rotation. Combined with high-protection sealing and vibration isolation design, the system ensures long-term stable operation under strong impact, high humidity, high temperature, and mud-containing environments. The technical solution of this invention solves the problems of existing cutterhead speed monitoring systems under TBM vibration conditions, such as power supply difficulties, severe signal interference, weak direction recognition capability, and insufficient sealing reliability.

Description

Technical Field

[0001] This invention belongs to the technical field of cutterhead tunnel boring machines, specifically relating to an online monitoring system for the rotational speed of a self-generating cutterhead that adapts to vibration conditions. Background Technology

[0002] The cutter head is a key component in the rock-breaking operation of a tunnel boring machine (TBM), and its rotational speed monitoring is crucial for understanding the cutter's operating status, assessing wear levels, and achieving intelligent control. Existing online cutter head rotational speed monitoring systems mostly employ eddy current sensing principles. This involves placing metal markers on the cutter body surface and using an eddy current sensor probe mounted on the side wall of the cutter holder to detect the electromagnetic signals generated when these markers pass by. After amplification and shaping, a square wave pulse signal is obtained, which is then calculated by a microprocessor to determine the cutter head rotational speed. This method is non-contact, has a fast response time, and high accuracy, and can operate stably in dusty, muddy, and humid environments, thus becoming the mainstream monitoring method.

[0003] Existing eddy current-based cutter speed measuring devices are generally well-suited for general operating conditions, but they still exhibit several common shortcomings in complex geological conditions such as strong vibration, high impact, and prolonged immersion in water: First, the power supply relies on wired feeders or primary batteries. The former is prone to insulation damage due to vibration and wear in the wiring near the rotating components, while the latter suffers from frequent replacement and reliability degradation under high humidity and temperature conditions, thus affecting the continuous operation of the system. Second, impact vibrations can induce parasitic pulses or cause gap fluctuations in the sensing link, leading to false triggering of counts and increased period dispersion, resulting in decreased speed calculation accuracy and potential short-term pulse loss. Third, single-probe structures typically only output scalar velocity without vectors, lacking robust determination of the cutter rotation direction, which is detrimental to attitude control and stress diagnosis. Fourth, conventional sealing levels are difficult to maintain for long periods in environments with muddy water and rock cuttings erosion. Without targeted structural and material designs, the sensor cavity and connectors are prone to water ingress or erosion, leading to intermittent failures. Based on the above shortcomings, there is an urgent engineering need for an integrated online monitoring system that combines self-generation, shock resistance, and high protection. Summary of the Invention

[0004] To address the problems existing in the prior art, this invention provides a self-generating cutter speed online monitoring system adapted to vibration conditions, solving the problems of power supply difficulties, severe signal interference, weak direction recognition capability, and insufficient sealing reliability of existing cutter speed monitoring systems under the vibration conditions of tunnel boring machines (TBMs).

[0005] To achieve the above objectives, the present invention provides the following solution: An online monitoring system for the rotational speed of a self-generating hob adapted to vibration conditions includes: a power generation cavity and dual eddy current sensors; wherein, the power generation cavity is an electromagnetic induction power generation module composed of a Halbach permanent magnet array and a stator coil disk; the Halbach permanent magnet array is fixed inside the cutter hub, and the stator coil disk is fixed outside the cutter shaft, forming a uniform radial air gap between the two; when the hob rotates, the Halbach permanent magnet array rotates synchronously with the cutter holder, and its inner magnetic field periodically cuts the effective edge of the stator coil conductor to generate an induced electromotive force; the dual eddy current sensors are arranged along the circumferential direction of the outer wall of the cutter holder, and the normal direction of their probes all points to the metal marking area on the outer peripheral surface of the cutter.

[0006] As a preferred option, a structural arrangement is adopted in which the cutter shaft is a stationary component and the cutter hub is a rotating component; a power generation cavity is set between the cutter shaft and the cutter hub.

[0007] Preferably, the probes of the eddy current sensors are all encapsulated with non-magnetic material shells and are fixedly connected to the tool holder by threaded supports. A limiting shoulder and a flexible vibration isolation pad are set between the threaded supports and the probe.

[0008] Preferably, the metal marking area is made of a highly conductive metal material.

[0009] Preferably, the rotation of the blade hub drives the power generation cavity to generate an induced current, which is rectified and regulated by the energy management and energy storage unit to power the dual eddy current sensor and signal processing module. The metal marker passes through the sensing area of ​​the dual eddy current sensor in sequence during rotation, outputting two phase-shifted signals, which are then calculated by the signal processing module to obtain the rotation speed and direction. When the energy storage voltage drops below a set threshold, it enters a sleep state; it automatically wakes up when the blade body resumes power generation.

[0010] Compared with the prior art, the beneficial effects of the present invention are as follows: This invention achieves energy self-sufficiency by integrating a simplified electromagnetic self-generating structure inside the cutter shaft; and uses orthogonally arranged dual eddy current sensors to achieve synchronous detection of the cutter speed and direction of rotation. At the same time, combined with a high-protection sealing and vibration isolation design, it ensures that the device can still operate stably for a long time in environments with strong impact, high humidity, high temperature and mud. Attached Figure Description

[0011] To more clearly illustrate the technical solution of the present invention, the drawings used in the embodiments are briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0012] Figure 1 This is a cross-sectional schematic diagram of the online monitoring system for the rotational speed of a self-generating hob adapted to vibration conditions according to an embodiment of the present invention; Figure 2 This is a radial cross-sectional view of the self-generating hob speed online monitoring system adapted to vibration conditions according to an embodiment of the present invention; Figure 3 This is a three-dimensional exploded view of the online monitoring system for the rotational speed of a self-generating hob, adapted to vibration conditions, according to an embodiment of the present invention. Detailed Implementation

[0013] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0014] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0015] Example 1 like Figures 1 to 3 As shown, the present invention provides an online monitoring system for the rotational speed of a self-generating hob that adapts to vibration conditions, comprising: a cutter hub 1, a cutter shaft 2, a power generation cavity 3, an energy management and storage unit 4, dual eddy current sensors 5A and 5B, a signal processing module 6, a sealing and vibration isolation structure 7, and a metal marking area 8 on the circumferential surface of the cutter body.

[0016] Furthermore, a structural arrangement is adopted where the cutter shaft 2 is a stationary component and the cutter hub 1 is a rotating component. A power generation cavity 3 is set between the cutter shaft 2 and the cutter hub 1, and an electromagnetic induction power generation module consisting of a Halbach permanent magnet array and a stator coil disk is installed inside the cavity. The Halbach permanent magnet array is fixed to the inner side of the cutter hub by structural adhesive and pressure fitting with limiting rings, while the stator coil disk is fixed to the outer side of the cutter shaft, forming a uniform radial air gap between them. The air gap thickness is approximately 1 mm to balance power generation efficiency and mechanical safety clearance. When the cutter rotates, the Halbach permanent magnet array rotates synchronously with the cutter hub, and its inner magnetic field periodically cuts the effective edge of the stator coil conductor to generate an induced electromotive force. Since the magnetic field of the Halbach array is focused on one side in the radial direction and attenuates on the outer side, the air gap region where the stator coil disk is located obtains a high-density, low-leakage magnetic flux cutting path. The induced electromotive force is rectified and regulated to power the energy management and energy storage unit, thereby realizing the system's self-generation and continuous operation. The power generation cavity adopts a high-permeability magnetic back iron and shielding ring structure, which closes the magnetic flux inside the cavity and reduces external magnetic leakage. The electromagnetic induction power generation module is completely sealed through epoxy potting, ensuring long-term reliable operation in high-pressure and muddy sand environments.

[0017] Dual eddy current sensors 5A and 5B are arranged circumferentially along the outer wall of the tool holder, with their probe normals pointing towards the metal marking area 8 on the outer circumferential surface of the tool body 1. The centers of the two probes form a fixed angular interval θ on the circumference, chosen to be 90°, to ensure a stable phase difference when the same metal mark passes through the sensing areas of the two probes sequentially during rotation. Each sensor probe is encapsulated in a non-magnetic material shell and fixedly connected to the tool holder via a threaded support. A limiting shoulder and a flexible vibration isolation pad are provided between the threaded support and the probe to ensure a stable detection gap and absorb excitation energy. A wear-resistant ceramic protective sleeve is provided at the front end of the probe, and an external labyrinth-type protective structure prevents mud, sand, and debris from entering the measurement area.

[0018] Six equidistant metal marking areas 8, made of highly conductive metal material, are set on the circumference of the cutter body. As the cutter body rotates, the metal markings sequentially pass through the sensing areas of the two probes. The high-frequency alternating magnetic field generated by the excitation coil induces eddy currents on the metal surface. The reverse magnetic field of the eddy currents changes the equivalent impedance of the probe coil, causing the probe output voltage amplitude to change periodically with time. The two probes have a fixed geometric interval in the circumferential direction, thus there is a time difference Δt between the output signals generated by the two probes for the same marking.

[0019] To ensure accurate identification of the hob's rotational speed and direction under TBM excitation and high-impact conditions, this invention designs a phase difference calculation algorithm based on an orthogonal structure of dual eddy current sensors in the signal processing module. Six equidistant metal marking areas are set on the outer circumference of the cutter head. When the hob rotates, the metal markings sequentially pass through the sensing areas of probes 5A and 5B, forming a periodic signal sequence. Since the two probes have a fixed angular interval θ (e.g., 90°) in the circumferential direction, the time delay Δt of the same mark appearing in the two signals reflects the rotational direction and angular velocity information. During hob operation, the overall excitation of the cutter head introduces significant low-frequency disturbances and amplitude fluctuations into the signal. The original signal output by the eddy current sensor can be considered as a superposition of the excitation fundamental frequency component and the marking periodic component. To accurately extract rotational features, this invention synchronously samples the dual-channel signal at a rate several times higher than the cutter head excitation frequency and performs bandpass filtering and DC-DC removal in the digital domain to filter out low-frequency components and energy fluctuations caused by excitation. The shaped signal generates 6 pairs of staggered pulse waveforms per revolution. The signal processing module calculates the phase difference between the two signals using a cross-correlation algorithm, the mathematical expression of which is: Where A(n) and B(n) are the sampled values ​​of signal A and signal B at time n, respectively; It is the time delay (i.e., the phase difference between signals); It is a cross-correlation function, representing the similarity between signals. The delay is calculated through cross-correlation operations. This corresponds to the signal propagation time from one sensor to another. In this way, the system can stably extract the effective signal related to tool rotation and suppress time shifts caused by noise. The delay estimation formula is: in, This is the optimal time lag estimate for the dual-probe signal. Based on... The sign determines the rotation direction: when the output waveform of probe A leads that of probe B ( When >0), it is determined to be a clockwise rotation; otherwise ( <0) indicates counterclockwise rotation. From this, the instantaneous angular velocity can be obtained: In the formula, θ is the geometric angle between the two probes on the circumference. To improve the accuracy of delay estimation, parabolic interpolation is used near the cross-correlation peak to refine the time resolution, making it better than the sampling period.

[0020] The sealing and vibration isolation structure 7 is located outside the eddy current sensor, serving as its protective sleeve. This structure is made of non-metallic materials with high hardness, high strength, and extremely high wear resistance, effectively isolating the surrounding rock and soil environment and avoiding the influence of surrounding metals on the eddy current sensor probe. It can maintain the system's dryness and stable operation for a long time in high humidity, high pressure, sandy slurry, and strong impact environments.

[0021] In summary, during system operation, the rotation of the cutter hub drives the power generation chamber to generate an induced current. After rectification and voltage regulation by the energy management and energy storage unit, this current powers the dual eddy current sensors and the signal processing module. As the metal marker rotates, it sequentially passes through the sensing areas of the dual eddy current sensors 5A and 5B, outputting two phase-shifted signals. The signal processing module calculates the rotation speed and direction. When the energy storage voltage drops below a set threshold, the system enters a sleep state; it automatically wakes up when the cutter body resumes power generation, forming a self-sustaining closed-loop operation mode of "power generation—energy storage—detection—output—sleep—wake-up," enabling long-term stable online monitoring without external power supply.

[0022] This invention achieves system energy self-sufficiency by constructing a sealed power generation cavity between the cutter shaft and the cutter hub; and employs dual eddy current sensors orthogonally arranged along the circumference to achieve synchronous detection of the hobbing speed and rotation direction. By combining a dual-channel differential algorithm, time-gated filtering, and phase-locked technology, vibration and electromagnetic interference are effectively suppressed, improving the stability of the detection signal and the accuracy of direction determination. The system has a compact structure, strong impact resistance, and a high level of sealing protection, enabling long-term stable operation in complex environments such as strong vibration, mud content, and high humidity and temperature.

[0023] The embodiments described above are merely preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Various modifications and improvements made by those skilled in the art to the technical solutions of the present invention without departing from the spirit of the present invention should fall within the protection scope defined by the claims of the present invention.

Claims

1. A self-generating hob speed online monitoring system adapted to vibration conditions, characterized in that, include: The device includes a power generation cavity and dual eddy current sensors. The power generation cavity is an electromagnetic induction power generation module composed of a Halbach permanent magnet array and a stator coil disk. The Halbach permanent magnet array is fixed inside the cutter hub, and the stator coil disk is fixed on the outer cylindrical surface of the cutter shaft, forming a uniform radial air gap between them. When the hob rotates, the Halbach permanent magnet array rotates synchronously with the cutter holder, and its inner magnetic field periodically cuts the effective edge of the stator coil conductor to generate an induced electromotive force. The dual eddy current sensors are arranged along the circumferential direction of the outer wall of the cutter holder, and the normal direction of their probes all points to the metal marking area on the outer peripheral surface of the cutter.

2. The self-generating hob speed online monitoring system adapted to vibration conditions as described in claim 1, characterized in that, The structure adopts a stationary cutter shaft and a rotating cutter hub; a power generation cavity is set between the cutter shaft and the cutter hub.

3. The self-generating hob speed online monitoring system adapted to vibration conditions as described in claim 2, characterized in that, The probes of the eddy current sensors are all encapsulated in non-magnetic material shells and are fixedly connected to the tool holder by threaded supports. A limiting shoulder and a flexible vibration isolation pad are set between the threaded supports and the probe.

4. The self-generating hob speed online monitoring system adapted to vibration conditions as described in claim 3, characterized in that, The metal marking area is made of a highly conductive metal material.

5. The self-generating hob speed online monitoring system adapted to vibration conditions as described in claim 4, characterized in that, The rotation of the blade hub drives the power generation chamber to generate an induced current, which is rectified and regulated by the energy management and energy storage unit to power the dual eddy current sensors and signal processing module. The metal marker passes through the sensing area of ​​the dual eddy current sensors in sequence during rotation, outputting two phase-shifted signals. The signal processing module calculates the rotation speed and direction. When the energy storage voltage drops below a set threshold, it enters a sleep state. It automatically wakes up when the blade body resumes power generation.

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