Field reduction device for magnetic resonance imaging equipment and magnetic resonance imaging equipment

Abstract

This utility model discloses a field-reducing device for a magnetic resonance imaging (MRI) device and the MRI device itself, including a heating unit and a control unit. The heating unit heats a temperature switch on the field-reducing device. The control unit is communicatively connected to the heating unit and the temperature switch, enabling it to control the heating unit's start and stop, acquire the open / closed state of the temperature switch, and determine the switch's effectiveness based on this state. By actively heating and reading the switch response, the operation of the temperature switch at a predetermined temperature can be verified, thereby promptly detecting faults such as permanent open / closed states or poor contact. This avoids false triggering or failure to trigger demagnetization due to temperature switch failure, reducing liquid helium consumption, downtime, and maintenance costs, and improving system reliability and availability.

Description

Technical Field

[0001] This utility model relates to the field of medical equipment technology, and in particular to a field reduction device for magnetic resonance imaging equipment and a magnetic resonance imaging equipment. Background Technology

[0002] During the demagnetization process of superconducting magnets used in magnetic resonance imaging (MRI) equipment, the large amount of magnetic energy stored in the system needs to be converted into heat energy and dissipated through a field-reducing device to achieve safe energy release. To avoid more serious consequences due to overheating of the field-reducing device, a temperature switch is usually installed on the field-reducing device as a protection measure.

[0003] However, temperature switches may experience permanent disconnection (normally open failure) or permanent closure (normally closed failure) due to long-term use or manufacturing defects in individual samples. This may make it difficult to detect abnormal conditions in a timely manner. Utility Model Content

[0004] This invention provides a field reduction device for a magnetic resonance imaging (MRI) device and an MRI device, which can detect the effectiveness of a temperature switch.

[0005] This utility model provides a field reduction device for a magnetic resonance imaging (MRI) apparatus, which includes an energy-consuming element for converting electrical energy in the MRI apparatus into heat energy, and further includes:

[0006] A temperature switch is disposed adjacent to the energy-consuming element and is configured to stop the field reduction operation by changing the switch state when the temperature exceeds a predetermined threshold, and is capable of notifying the monitoring unit of the magnetic resonance imaging device of the switch state.

[0007] A heating unit is disposed adjacent to the temperature switch and can be controlled to start before the field reduction operation is performed to heat the temperature switch, thereby detecting whether the temperature switch can change its switching state when the temperature exceeds a predetermined threshold.

[0008] A heating unit is disposed adjacent to the temperature switch and can be controlled to start before the field reduction operation is performed to heat the temperature switch, thereby detecting whether the temperature switch can change its switching state when the temperature exceeds a predetermined threshold.

[0009] In one embodiment of the present invention, a timing unit is further included. The timing unit is used to time the start-up time of the heating unit and to determine whether the temperature switch is effective based on the start-up time and the open / closed state of the temperature switch.

[0010] In one embodiment of the present invention, a temperature sensor is further included. The temperature sensor is connected to the temperature switch to detect the temperature at the temperature switch, and the effectiveness of the temperature switch is determined based on the temperature detected by the temperature sensor and the open / closed state of the temperature switch.

[0011] In one embodiment of the present invention, the heating unit is activated according to a preset time interval.

[0012] In one embodiment of the present invention, an independent power supply is also included, and the heating unit is connected to the independent power supply.

[0013] In one embodiment of the present invention, a control unit is further included. The independent power supply includes a DC power interface. The control unit is provided with a connection unit, which selectively connects the DC power interface to the heating unit under the control of the control unit.

[0014] In one embodiment of the present invention, the temperature sensing part of the temperature switch is attached to the diode assembly of the field reduction device, and the heating unit is an attached structure to be attached to the temperature sensing part of the temperature switch.

[0015] This utility model also provides a magnetic resonance imaging device, including:

[0016] Magnet assembly;

[0017] The field-lowering device is the field-lowering device described above.

[0018] In one embodiment of the present invention, the heating unit is used to determine whether the field-lowering device can be started based on its working status.

[0019] In one embodiment of the present invention, the field reduction device is used to issue an alarm and / or issue a disable message to the magnetic resonance imaging device based on the failure information of the temperature switch.

[0020] The beneficial effects of this invention are as follows: By heating the temperature switch and reading its open / closed state, the above solution can confirm whether the switch operates at the expected temperature, thus verifying its effectiveness. It also prevents unnecessary demagnetization due to temperature switch malfunction, reducing liquid helium consumption, downtime, and maintenance costs. Attached Figure Description

[0021] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with this application and, together with the description, serve to explain the principles of this application. It is obvious that the drawings described below are merely some embodiments of this application, and those skilled in the art can obtain other drawings based on these drawings without any inventive effort.

[0022] In the attached diagram:

[0023] Figure 1 This is a schematic diagram of the self-testing system of the field-dropping device provided in one embodiment of the present invention;

[0024] Figure 2 This is a simplified structural diagram of a magnetic resonance imaging device provided in one embodiment of the present invention.

[0025] The attached figures are labeled as follows:

[0026] 10. Field reduction device; 11. Diode assembly; 20. Temperature switch; 30. Heating unit; 40. Control unit; 41. Connection unit; 42. DC power interface; 50. Magnet assembly; 60. Temperature sensor; 70. Monitoring unit. Detailed Implementation

[0027] The following specific examples illustrate the implementation of this utility model. Those skilled in the art can easily understand other advantages and effects of this utility model from the content disclosed in this specification. This utility model can also be implemented or applied through other different specific embodiments. Various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of this utility model. In the absence of conflict, the following embodiments and features in the embodiments can be combined with each other.

[0028] It should be noted that the illustrations provided in the following embodiments are only schematic representations of the basic concept of the present invention. The drawings only show the components related to the present invention and are not drawn according to the actual number, shape and size of the components. In actual implementation, the form, quantity and proportion of each component can be arbitrarily changed, and the layout of the components may also be more complex.

[0029] In the following description, numerous details are explored to provide a more thorough explanation of embodiments of the present invention. However, it will be apparent to those skilled in the art that embodiments of the present invention may be practiced without these specific details. In other embodiments, well-known structures and devices are shown in block diagram form rather than in detail to avoid obscuring embodiments of the present invention.

[0030] During the demagnetization process of superconducting magnets used in magnetic resonance imaging (MR) equipment, the large amount of magnetic energy stored in the system needs to be released safely and in a controlled manner. A commonly used rampdownload (RDL) device uses diode components to convert electrical energy into heat and dissipate it, thus achieving safe energy release. The diodes withstand large currents during rampdown or demagnetization, and the forward voltage drop of the device generates a significant amount of heat. Heat dissipation of the diode components typically relies entirely on forced convection cooling by fan components. The fan operates continuously to remove the heat generated by the diode, keeping the device temperature below an acceptable threshold. If the fan fails, the diode temperature will rise rapidly, posing a risk of overheating or even thermal breakdown, leading to diode damage. If the rampdownload fails, the system loses a reliable energy dissipation path, potentially causing the magnet to demagnetize unsafely as designed, or even resulting in uncontrolled demagnetization, which could damage the magnet or surrounding equipment, causing prolonged downtime and high maintenance costs.

[0031] To prevent more serious consequences from diode overheating, a temperature switch is usually installed on the field reduction device as a protective measure. When the temperature exceeds a predetermined threshold, the temperature switch opens to trigger the magnet to demagnetize (quench). This quickly releases magnetic energy by intentionally bringing all or part of the coil into a normal resistance state, thereby protecting the field reduction device from further damage.

[0032] However, although temperature switches are designed as protective components to be permanently installed in MR systems and have a service life of approximately 10 years, various failure modes and potential risks still exist in actual operation. Temperature switches may experience failure states such as permanent disconnection (normally open failure) or permanent closure (normally closed failure) due to long-term use or manufacturing defects in individual samples. Thermal cycling fatigue, contact oxidation or corrosion, mechanical vibration leading to contact damage, solder joint or connector failure, manufacturing defects, and unexpected electrical overstress can all cause temperature switch performance degradation or failure.

[0033] Temperature switches typically function as a single, passive protection element. If they permanently disconnect or close in the field, the MR system may struggle to detect the anomaly in a timely manner. This is especially true during normal operation when there is a lack of proactive self-checks or link integrity checks, meaning the fault may remain a potential hazard until a major event occurs. For example, if a temperature switch fails, and a fan failure causes the diode to overheat, the expected protection action will not be triggered. The diode may burn out due to overheating, potentially damaging the field-setting device or compromising magnet safety.

[0034] Please see Figure 1 , Figure 2 , Figure 1An embodiment of the present invention provides a field reduction device 10 for use in a magnetic resonance imaging device. The field reduction device 10 can convert electrical energy in the magnetic resonance device into heat energy using energy-consuming elements when performing field reduction operation. The field reduction device 10 includes a temperature switch 20, a heating unit 30, and a control unit 40.

[0035] The temperature switch 20 is configured to stop the field reduction operation by changing the switch state when the temperature exceeds a predetermined threshold, and can notify the monitoring unit 70 of the magnetic resonance imaging equipment of the switch state.

[0036] The heating unit 10 is disposed adjacent to the temperature switch 20 and can be controlled to start before the field-dropping operation to heat the temperature switch 20, thereby detecting whether the temperature switch 20 can change its switching state when the temperature exceeds a predetermined threshold. The heating unit 30 is used to heat the temperature switch 20 on the field-dropping device 10. The heating unit 30 may specifically be a thin-film flexible heating sheet, a ceramic or metal plug resistance heater, a PTC self-regulating heater, a silicone heating pad, or a miniature hot air / infrared heater, etc.

[0037] In one embodiment of this utility model, the temperature sensing part of the temperature switch 20 is attached to the diode assembly 11 of the field-reducing device, and the heating unit 10 has an attached structure to be attached to the temperature sensing part of the temperature switch 20. This establishes a tight thermal contact between the heating element and the temperature sensing part of the temperature switch 20, allowing heat to be efficiently and controllably transferred to the body of the temperature switch 20. This can be achieved using thermally conductive pads or sheets, thermally conductive adhesive / double-sided adhesive, flexible heating sheets, and snap-fit / clamping structures, etc., to ensure low thermal resistance and stable mechanical fixation. The attached heating significantly shortens the time required for the temperature switch 20 to reach its operating conditions and improves repeatability and comparability, thereby making self-testing faster and more reliable, and enabling detection with lower heating energy, reducing the thermal impact on surrounding components.

[0038] The control unit 40 is communicatively connected to the heating unit 30 to control the heating unit 30 to start or stop. The control unit 40 is also communicatively connected to the temperature switch 20 to obtain the open / closed state of the temperature switch 20. The control unit 40 is used to determine whether the temperature switch 20 is effective based on its open / closed state. The control unit 40 can be integrated as part of the field reduction device 10 (reducing wiring, simplifying installation, and enabling synchronous control), or it can be set up as an independent module (improving electrical isolation and facilitating maintenance and replacement).

[0039] The operation of the control unit 40 is as follows: The control unit 40 drives the heating unit 30 to heat the temperature switch 20. After heating begins, the control unit 40 collects the electrical state (normally closed / normally open) of the temperature switch 20 in real time. If the temperature switch 20 switches as expected according to the design logic within the specified temperature rise range or timeout period (e.g., from closed to open when the temperature exceeds the threshold), the temperature switch 20 is deemed valid. If the temperature switch 20 is already open before heating (possibly permanently open), fails to switch during heating, or remains open after heating, it is deemed abnormal and an alarm is generated or the maintenance process is initiated. This self-test can be automatically executed during periodic maintenance or online according to planned / triggered conditions, and can detect failure modes such as permanent closure, permanent opening, poor contact, or delayed response before the actual temperature rise event occurs.

[0040] In one embodiment of this utility model, a timing unit is added to the control unit 40 (the timing unit can be an internal hardware timer of the MCU, an independent real-time timer, an FPGA timing module or a dedicated timing chip) to time the start time (the time from the start of heating to the end of heating) of the heating unit 30. The control unit 40 determines whether the temperature switch 20 is effective by reading the start time and combining it with the open / closed state of the temperature switch 20.

[0041] In the above scheme, the control unit 40 issues a heating command, the heating unit 30 is powered on and begins to heat up. Simultaneously, the timing unit starts timing and monitors the temperature switch 20 signal in real time. The effectiveness of the temperature switch 20 is determined based on the start-up time and the open / closed state of the temperature switch 20. Each self-test records the operating time, reset time, timeout status, and abnormality type of the temperature switch 20. Long-term statistics are used to determine the aging trend of the temperature switch 20 and schedule maintenance in advance. This provides quantifiable historical data to support trend analysis and predictive maintenance, allowing for the early replacement of aging components and reducing unexpected downtime and repair costs.

[0042] In one embodiment of this utility model, the control unit 40 uses a preset time threshold as a judgment point during self-testing: when self-testing starts, the control unit 40 drives the heating unit 30 to heat the temperature switch 20, and the timing unit accumulates the start time. When the accumulated time reaches the preset threshold, the electrical state of the temperature switch 20 is read. If it is open (conforming to the design logic from closed to open), the temperature switch 20 is determined to be effective. If it is still closed, the temperature switch 20 is determined to be ineffective. The cooling reset time can also be recorded after heating stops to detect lag or jamming, and the judgment result is logged and reported to the control / maintenance system. In case of abnormality, an alarm is triggered, the automatic demagnetization strategy relying on the temperature switch 20 is disabled, or the system switches to redundant protection.

[0043] In one embodiment of this invention, a temperature sensor 60 (thermocouple or high-precision NTC sensor) is added and connected to the temperature switch 20 for real-time measurement of the actual temperature at the temperature switch 20. The control unit 40 simultaneously reads the temperature value of the temperature sensor 60 and the electrical status of the temperature switch 20 for joint judgment, significantly reducing false alarms and missed alarms, and accurately distinguishing between temperature switch 20 faults and temperature measurement link faults. Using temperature as a control variable allows for timely cutting off of heating / taking protective measures during self-testing or operation. Simultaneously, historical temperature and action time data can be used to determine aging trends and formulate maintenance plans, reducing sudden downtime and maintenance costs. Furthermore, the heating duration and power during self-testing can be dynamically adjusted according to the actual temperature, shortening the necessary self-testing time.

[0044] In one embodiment of this utility model, the control unit 40 is used to determine whether the temperature switch 20 is effective based on the temperature detected by the temperature sensor 60 and the open / closed state of the temperature switch 20. The joint determination by the temperature sensor 60 and the temperature switch 20 significantly improves fault identification capability and self-test reliability. It can confirm the effectiveness of the protection path when the temperature switch 20 matches the temperature, and can quickly locate whether the fault lies with the temperature switch 20 or the temperature measurement link when they do not match, reducing false alarms and missed alarms.

[0045] In one embodiment of this utility model, the control unit 40 performs a joint judgment by simultaneously reading the temperature value of the temperature sensor 60 and the electrical state of the temperature switch 20: when the temperature measured by the sensor reaches a preset action threshold (e.g., the nominal action temperature of the temperature switch 20) and the temperature switch 20 is in the open state, the control unit 40 determines that the temperature switch 20 is effective. If the sensor has reached the threshold but the temperature switch 20 is still closed, the temperature switch 20 is determined to be faulty (possibly jammed or with contact failure). This joint judgment method associates temperature measurement with the state of the temperature switch 20, accurately distinguishing between situations such as "temperature switch 20 is activated according to temperature," "temperature switch 20 is faulty (closed but not activated)," and "temperature switch 20 malfunctions (open but temperature has not reached the threshold)," thereby reducing false alarms / missed alarms and quickly locating the source of the fault, improving the reliability of the protection path and the security of the system.

[0046] In one embodiment of this utility model, the control unit 40 starts the heating unit 30 at preset time intervals to perform a self-test of the temperature switch 20. In practice, the interval is managed by a timer or scheduling module in the control unit 40, and can be a fixed period or a condition-based adaptive period (e.g., adjusted based on historical response trends, operating load, or maintenance window). Automatic startup based on preset time intervals enables continuous, controllable, and proactive self-testing without manual intervention, thereby detecting faults such as permanent closure, permanent disconnection, hysteresis, or poor contact at an early stage, reducing the risk of sudden protection failures on-site. Periodic data accumulation supports trend analysis and predictive maintenance, reducing unplanned downtime and optimizing maintenance schedules.

[0047] For example, when the MRI equipment is shut down, a scheduled self-test is performed to confirm the normal operation of temperature switch 20 and the activation time is recorded. After an operational anomaly or overheating event, more frequent self-tests are immediately triggered to verify the continued reliability of the protective components. Long-term statistical analysis reveals a gradual increase in response time, automatically shortening the self-test interval and reporting to maintenance for early component replacement. Overall, the timed start-up mechanism achieves predictability and manageability of automated detection, while minimizing disruption to normal operation and improving system reliability by combining it with safety limits and operational plans.

[0048] In one embodiment of this utility model, an independent power supply is also included. This independent power supply provides electrical energy to the heating unit 30 and the control unit 40, independent of the main power supply. Both are connected to and powered by this independent power supply. The independent power supply can take the form of a battery, a backup power unit, or a dedicated power module with isolated output, and has necessary monitoring and protection circuits (such as voltage / current monitoring, overcharge / over-discharge protection, short-circuit protection, and status indication). Introducing an independent power supply allows the temperature switch 20 to perform self-tests or critical protection actions even when the main power supply fails or malfunctions. When the main power supply fails, necessary self-tests can still be completed and the status reported for remote maintenance team decision-making. When the main power supply experiences significant load fluctuations, the measurement and control circuit powered by the independent power supply maintains stable sampling and judgment, reducing false judgments. During on-site maintenance or system upgrades, only the main power supply needs to be disconnected, while the independent power supply maintains self-test and alarm functions, improving maintenance safety and system maintainability.

[0049] Please see Figure 1 , Figure 2 The independent power supply includes a DC power interface 42 (e.g., a DC 24V interface); the control unit is equipped with a connection unit 41 (exemplarily implemented as a power switching element, such as a MOSFET); under the control of the control unit 40, the connection unit 41 selectively connects the DC power interface 42 to the heating unit 30 (the heating element attached to the temperature switch). Through the cooperation of the independent power supply and the controllable connection unit 41, the temperature switch can reliably perform active self-testing when the main power supply is abnormal, the system is idle, or as scheduled, avoiding passively waiting for faults to be exposed.

[0050] like Figure 2 As shown, this utility model also provides a magnetic resonance imaging device, including a magnet assembly 50 and the aforementioned field reduction device 10.

[0051] The function of the field reduction device 10 is to safely dissipate the electrical or magnetic energy stored in the magnet assembly 50 in the form of heat energy. The field reduction device 10 is implemented by a resistive field reduction device (e.g., a diode).

[0052] Temperature switch 20 is connected and installed with cooling device 10 to sense the temperature of the surface or key parts of cooling device 10 in real time and to open or close according to its own structural characteristics in order to complete over-temperature protection or reset control.

[0053] In one embodiment of this utility model, the control unit 40 is communicatively connected to the field-cooling device 10 to obtain the operating status of the field-cooling device 10. The control unit 40 determines whether the heating unit 30 can be started based on the operating status. The control unit 40 reads or receives the operating status of the field-cooling device 10 (e.g., whether it is in energy release / field-cooling operation, whether there is a fault alarm, whether cooling / heat dissipation is in place, whether it is in maintenance or isolation mode, etc.). Based on these statuses, the control unit 40 adds an authorization check when determining whether the self-test start-up conditions are met. When the field-cooling device 10 reports being in any of the above-mentioned states that do not allow start-up, the control unit 40 will prohibit the start-up of the heating unit 30 and record the decision. This mechanism can effectively avoid heating when the field-cooling device 10 is dissipating energy or is in an abnormal / maintenance situation, thereby reducing the risk of superimposed heat load, device damage, and misjudgment.

[0054] In one embodiment of this invention, when the control unit 40 detects that the temperature switch 20 has failed, it will immediately issue an alarm according to a preset strategy and / or place the magnetic resonance imaging equipment in a disabled or restricted operating state. This measure can quickly cut off potentially dangerous paths when the temperature protection element fails, preventing continued operation without effective temperature protection, thereby reducing the risk of overheating or damage to the field reduction device 10, magnet assembly 50, and peripheral equipment, and ensuring the safety of personnel and patients. For example, if the temperature switch 20 fails to operate when it should during a self-test, the control unit 40 issues an alarm and places the magnetic resonance imaging equipment in a disabled operating state to await maintenance.

[0055] In summary, this invention significantly improves the reliability and dependability of the self-testing and protection circuit of the temperature switch 20, enabling early detection of permanent closure, permanent disconnection, hysteresis, poor contact, or abnormal temperature measurement link, and quickly locating the source of the fault, reducing false alarms and missed alarms. By communicating with the de-field device 10 and disabling self-testing when not permitted, it avoids superimposed heat loads and device damage, improving operational safety. An independent power supply ensures necessary self-testing and alarming can still be completed in the event of main power failure or power outage, supporting remote reporting and maintenance decision-making. Timing records and historical temperature data provide quantitative basis for trend analysis and predictive maintenance, reducing unplanned downtime and maintenance costs. When the temperature switch 20 is determined to have failed, an alarm can be issued immediately, and equipment operation can be restricted or disabled, thereby protecting the magnet assembly 50 and surrounding equipment and ensuring personnel safety. Overall, this solution balances real-time performance, traceability, and failure safety, improving the reliability, maintainability, and operational safety of the magnetic resonance imaging equipment de-fielding protection system.

[0056] The above embodiments are merely illustrative of the principles and effects of this utility model and are not intended to limit the scope of this utility model. Any person skilled in the art can modify or alter the above embodiments without departing from the spirit and scope of this utility model. Therefore, all equivalent modifications or alterations made by those skilled in the art without departing from the spirit and technical concept disclosed in this utility model should still be covered by the claims of this utility model.

Claims

1. A field lowering device of a magnetic resonance imaging apparatus comprising an energy consuming element for performing a conversion of electrical energy in the magnetic resonance imaging apparatus into heat energy, characterized in that, Also includes: A temperature switch is disposed adjacent to the energy-consuming element and is configured to stop the field reduction operation by changing the switch state when the temperature exceeds a predetermined threshold, and is capable of notifying the monitoring unit of the magnetic resonance imaging device of the switch state. A heating unit is disposed adjacent to the temperature switch and can be controlled to start before the field reduction operation is performed to heat the temperature switch, thereby detecting whether the temperature switch can change its switching state when the temperature exceeds a predetermined threshold.

2. The field lowering device of a magnetic resonance imaging apparatus according to claim 1, characterized in that, It also includes a timing unit, which is used to time the start-up time of the heating unit.

3. The field lowering device of a magnetic resonance imaging apparatus as claimed in claim 1, characterized in that, It also includes a temperature sensor, which is connected to the temperature switch to detect the temperature at the temperature switch.

4. The field reduction device of the magnetic resonance imaging equipment according to claim 1, characterized in that, The heating unit is activated according to a preset time interval.

5. The magnetic field lowering device of a magnetic resonance imaging apparatus according to claim 1, characterized in that, It also includes an independent power supply, and the heating unit is connected to the independent power supply.

6. The field lowering device of a magnetic resonance imaging apparatus as claimed in claim 5, characterized in that, It also includes a control unit, the independent power supply includes a DC power interface, the control unit is provided with a connection unit, and the connection unit selectively connects the DC power interface to the heating unit under the control of the control unit.

7. The field reduction device of the magnetic resonance imaging equipment according to claim 1, characterized in that, The temperature sensing part of the temperature switch is attached to the diode assembly of the field reduction device, and the heating unit is a bonding structure attached to the temperature sensing part of the temperature switch.

8. A magnetic resonance imaging apparatus, characterized by include: Magnet assembly; The field-dropping device is the field-dropping device as described in any one of claims 1-7.

9. The magnetic resonance imaging device according to claim 8, characterized in that, The heating unit is activated according to the operating status of the cooling field device.

10. The magnetic resonance imaging device according to claim 8, characterized in that, The field reduction device issues an alarm and / or sends a disable message to the magnetic resonance imaging device based on the failure information of the temperature switch.

Images