Method for preventing damage from fan reverse rotation

Abstract

The application provides a method for preventing damage caused by reverse rotation of a fan, and belongs to the technical field of fans, and comprises the following steps: (1) a rotation speed sensor is installed on a low-speed shaft end cover of a gear box of the fan, for monitoring the rotation speed of the low-speed shaft of the gear box in real time and outputting a rotation speed signal; (2) the rotation speed signal output by the rotation speed sensor is input into a control system together with an operation signal of the fan; (3) when the operation signal of the fan is 0 and the rotation speed signal is not 0, it is determined that the fan is in a reverse rotation state; (4) in the reverse rotation state, an electric pump is automatically started by the control system to provide lubricating oil for sliding bearings of the gear box of the fan, and the control system sends an alarm message; (5) after a valve is closed by an operation and maintenance personnel, the rotation speed of the low-speed shaft of the gear box is reduced to 0, and the electric pump is automatically turned off after a delay for a period of time. The application installs a rotation speed sensor on an existing gear box of a fan, so that real-time monitoring of a reverse rotation state of the fan is realized.

Description

Technical Field

[0001] This invention relates to the field of wind turbine technology, and in particular to a method for preventing wind turbines from being damaged by reverse rotation. Background Technology

[0002] Turbine blowers are commonly used for vacuuming in paper machines. In actual operation, multiple blowers are typically configured to work in parallel on a single production line. The blower inlet pipes are connected together. When one blower is shut down for maintenance, valves are usually installed on each blower's inlet pipe to prevent backflow and subsequent reverse rotation. During maintenance, these valves are closed electrically or manually to prevent reverse rotation. However, if an unexpected situation occurs and the valves fail to close in time, the blower's reverse rotation will damage the impeller, causing significant economic losses to the customer. Furthermore, there are no warnings or indications for reverse rotation, making it difficult to detect in a timely manner.

[0003] In existing technologies, a check valve is typically added at the outlet of the fan duct. However, the opening resistance of the check valve increases the fan's operating load, leading to increased power consumption or insufficient inlet vacuum, thus affecting production. Furthermore, when the fan is stopped, if the duct valve fails to close in time due to unforeseen circumstances, the fan itself cannot provide timely warnings or take measures to prevent reverse rotation damage. Therefore, a method to prevent fan reverse rotation damage is needed. Summary of the Invention

[0004] The purpose of this invention is to provide a method for preventing wind turbines from being damaged by reverse rotation, solving the technical problem that existing wind turbine equipment cannot provide timely early warning and take measures to ensure that it is not damaged by reverse rotation. The method of this invention can detect reverse rotation in a timely manner when the wind turbine is stopped and automatically take protective measures to avoid equipment damage.

[0005] To achieve the above objectives, the technical solution adopted by the present invention is as follows: A method for preventing damage to a fan by reversing its rotation includes the following steps: (1) Install a speed sensor on the low-speed shaft end cover of the wind turbine gearbox to monitor the speed of the low-speed shaft of the gearbox in real time and output the speed signal; (2) Input the speed signal output by the speed sensor and the operating signal of the fan into the control system; (3) When the control system determines that the fan's operating signal is 0 and the speed signal is not 0, it determines that the fan is in reverse rotation. (4) In the reverse state, the control system automatically starts the electric pump to provide lubricating oil to the sliding bearing of the fan gearbox, and at the same time the control system issues an alarm message; (5) After the maintenance personnel close the valve to the correct position, the speed of the low-speed shaft of the gearbox drops to 0, and the electric pump automatically shuts off after running for a period of time.

[0006] Furthermore, the speed sensor is mounted on the low-speed shaft end cover via a sensor bracket, which is fixed to the low-speed shaft end cover with bolts. The distance between the probe of the speed sensor and the surface of the coupling is adjusted by a nut.

[0007] Furthermore, the speed sensor is an electromagnetic induction sensor that measures the speed of the low-speed shaft of the gearbox by the change in magnetic flux caused by the small hole on the coupling.

[0008] Furthermore, the bearings inside the fan gearbox are configured as sliding bearings, with oil supplied by a mechanical pump during normal operation and by an electric pump during reverse operation.

[0009] Furthermore, the control system records the reversal fault information while issuing alarm information.

[0010] Furthermore, the electric pump automatically shuts off after running for 2 to 10 minutes after the fan speed drops to 0.

[0011] A system for preventing damage to a fan from reverse rotation includes a drive motor, a fan gearbox, a speed sensor for monitoring the speed of the low-speed shaft of the gearbox, a control system, and an oil pump system. The drive motor is connected to the low-speed shaft of the fan gearbox via a coupling. The speed sensor is mounted on the end cover of the low-speed shaft of the fan gearbox. The control system is connected to the drive motor, the speed sensor, and the oil pump system.

[0012] Furthermore, the coupling has a small hole, and the probe of the speed sensor is positioned directly above the small hole.

[0013] Furthermore, the oil pump system includes an electric pump and a mechanical pump, which are respectively connected to the control system, and the electric pump and the mechanical pump provide lubricating oil to the fan gearbox.

[0014] The present invention, by adopting the above-described technical solution, has the following beneficial effects: This invention adds a speed sensor to the existing wind turbine gearbox to monitor the speed of the low-speed shaft of the gearbox. The speed signal of the low-speed shaft is combined with the wind turbine's operating signal and transmitted to the control system, thereby realizing real-time monitoring of the wind turbine's reverse rotation state.

[0015] This invention utilizes the original fan control system for logical judgment and control, resulting in low modification costs and ease of implementation.

[0016] When the fan reverses, this invention can automatically start the electric pump to provide lubricating oil, effectively preventing damage to key components such as shafts and bearings in the gearbox due to lack of lubrication, thus achieving active protection of the equipment; at the same time, it issues an alarm message to remind maintenance personnel to deal with the reverse fault in time, avoid the accident from escalating, and improve the reliability and security of equipment operation. Attached Figure Description

[0017] Figure 1 This is a flowchart illustrating the method for preventing damage to a fan by reverse rotation according to the present invention. Figure 2 This is a schematic diagram of the structure of the system for preventing fan reverse rotation and damage according to the present invention; Figure 3 This is a schematic diagram of the installation of the speed sensor of the present invention.

[0018] In the attached diagram, 1-drive motor, 2-control system, 3-coupling, 3-1-small hole, 4-speed sensor, 5-sensor mounting bracket, 6-fan gearbox, 7-mechanical pump, 8-electric pump, 9-fixing bolt, 10-low-speed shaft end cover, 11-gearbox low-speed shaft, 12-fixing nut. Detailed Implementation

[0019] To make the objectives, technical solutions, and advantages of the present invention clearer, the present invention will be further described in detail below with reference to the accompanying drawings and preferred embodiments. However, it should be noted that many details listed in the specification are merely to provide the reader with a thorough understanding of one or more aspects of the present invention, and these aspects of the invention can be implemented even without these specific details.

[0020] A method for preventing damage to a fan by reversing its rotation includes the following steps: Step 1: Real-time monitoring and signal acquisition: During the operation of the wind turbine, the speed sensor installed on the low-speed shaft end cover continuously monitors the speed of the low-speed shaft of the gearbox and outputs the real-time speed signal to the control system. At the same time, the control system also acquires the wind turbine's operating signal in real time.

[0021] Step 2: Control System Logic Judgment: After receiving the speed signal and the fan operation signal, the control system makes judgments according to the preset logic. When the control system determines that the fan operation signal is 0 (i.e., the fan is in a stopped or non-generating state) and the speed signal received from the speed sensor is not 0, it determines that the fan is currently in an abnormal reverse state. This condition usually occurs after the fan stops, when the wind turbine drives the low-speed shaft of the gearbox to rotate in the opposite direction due to the strong wind.

[0022] Step 3: Automatic Reverse Protection Activation: Upon determining that the fan is in reverse rotation, the control system immediately issues a start command to activate the electric pump. The electric pump then begins operation, forcibly providing lubricating oil to critical friction parts such as the sliding bearings of the fan gearbox. This ensures that all components receive sufficient lubrication and cooling during reverse rotation, preventing serious accidents such as bearing failure due to insufficient lubrication caused by the mechanical pump malfunctioning. Simultaneously, the control system issues an alarm to notify maintenance personnel. Preferably, while issuing the alarm, the control system also automatically records key information such as the occurrence time and duration of the reverse rotation fault in its internal memory, providing data support for subsequent fault analysis and equipment maintenance.

[0023] Step 4: Manual Intervention and Automatic Pump Shutdown: Upon receiving the alarm information, maintenance personnel rush to the site for inspection and handling. They close the corresponding valve at the fan inlet, preventing airflow from acting on the impeller. As the airflow is cut off, the speed of the gearbox's low-speed shaft gradually decreases until it reaches zero. When the control system detects a speed signal of zero, it does not immediately shut down the electric pump but instead controls it to run for a delayed period before automatically shutting it off. This delayed shutdown design ensures that after the shaft comes to a complete stop, the lubricating oil still has sufficient time to perform final circulation lubrication and heat dissipation on the bearings, providing better protection. Preferably, this delay time can be set to 2-10 minutes, for example, 5 minutes. The specific duration can be adjusted according to the gearbox's lubrication requirements and actual operating conditions.

[0024] This invention adds a speed sensor to the gearbox of an existing blower (HGC series blower) to monitor the speed of the low-speed shaft of the gearbox. The speed signal of the low-speed shaft is transmitted to the control system in conjunction with the operation signal of the blower, thereby realizing real-time monitoring of the blower's reverse rotation state.

[0025] This invention achieves automatic identification and protection against reverse rotation of the fan by adding simple speed monitoring and logic control, effectively avoiding the risk of equipment damage caused by reverse rotation, improving the operational reliability and safety of the fan, and reducing maintenance costs.

[0026] like Figure 2-3As shown, a system for preventing damage to a fan from reverse rotation includes a drive motor 1, a fan gearbox 6, a speed sensor 4 for monitoring the rotational speed of the low-speed shaft 11 of the gearbox, a control system 2, and an oil pump system. The drive motor 1 is connected to the low-speed shaft 11 of the fan gearbox 6 via a coupling 3 to transmit power. To achieve real-time monitoring of reverse rotation, the speed sensor 4 is installed on the low-speed shaft end cover 10 of the fan gearbox 6 to monitor the rotational speed of the low-speed shaft 11 in real time and output a corresponding speed signal. The control system 2 is connected to the drive motor 1, the speed sensor 4, and the oil pump system to receive signals and issue control commands. This invention has a simple structure, utilizing the original fan control system and adding only a speed sensor to achieve self-protection of the equipment, improving the reliability and safety of equipment operation.

[0027] like Figure 3 As shown, the speed sensor 4 is mounted on the low-speed shaft end cover 10 via a sensor bracket 5. The sensor bracket 5 is fixed to the low-speed shaft end cover by fixing bolts 9 and locked in place. The distance between the probe of the speed sensor 4 and the surface of the coupling 3 is adjusted by nuts 12. The speed sensor 4 is fixed to the sensor bracket 5 by two nuts 12. By adjusting the nuts, the distance between the speed sensor 4 and the surface of the coupling 3 under test can be easily adjusted to ensure optimal signal acquisition. The coupling 3 is provided with a small hole 3-1. A small hole or other feature that can cause a change in magnetic flux (such as a groove, protrusion, etc.) can be machined on the circumference of the coupling 3. The probe of the speed sensor 4 is positioned directly above the small hole 3-1. The speed sensor 4 is an electromagnetic induction sensor that measures the speed of the low-speed shaft of the gearbox by the change in magnetic flux caused by the small hole 3-1 on the coupling 3. When the low-speed shaft 11 rotates, the small hole 3-1 on the coupling periodically passes through the probe of the speed sensor 4, causing a periodic change in the magnetic flux passing through the probe coil. According to Faraday's law of electromagnetic induction, a changing magnetic flux will induce an electromotive force (voltage) in the coil. The faster the magnetic flux changes (the higher the rotational speed), the larger the amplitude and the higher the frequency of the voltage pulse generated. By measuring the frequency of this pulse voltage, the rotational speed of the shaft can be accurately calculated: rotational speed (RPM) = (pulse frequency / number of holes) × 60, thus outputting the rotational speed signal.

[0028] In an embodiment of the present invention, the oil pump system includes an electric pump 8 and a mechanical pump 7, which are respectively connected to the control system 2. The electric pump 8 and the mechanical pump 7 provide lubricating oil to the fan gearbox 6. The bearings inside the fan gearbox 6 are sliding bearings. During normal operation, the mechanical pump 7 supplies oil, and during reverse operation, the electric pump 8 supplies oil. The sliding bearings inside the fan gearbox 6 require lubricating oil to provide an oil film, provide support, and remove frictional heat. The control system 2 records reverse fault information while issuing an alarm message. The electric pump continues to run for 2-10 minutes after the fan speed drops to 0 before automatically shutting down. The fan gearbox 6 has sufficient lubrication to ensure that important components such as shafts, bearings, and gears are not damaged. At the same time, the system interface displays an alarm message and outputs reverse fault information, reminding maintenance personnel to check the actual situation on site and completely close the valve. After the valve is closed, the fan speed drops to 0, and the electric pump runs for a delay of 2-10 minutes before automatically shutting down.

[0029] Example During startup, the electric pump starts first to provide oil pressure, then the drive motor speeds up to its rated speed, and the mechanical pump connected to the drive motor shaft also rotates synchronously to start pumping oil. At this time, both pumps work simultaneously, and the speed sensor displays the speed of the gearbox low-speed shaft (or drive motor). After the equipment is running stably, the electric pump is powered off and stops working, and only the mechanical pump provides oil pressure. During shutdown, the electric pump is turned on first, and after the drive motor stops rotating, the electric pump continues to work for a period of time before being powered off.

[0030] When the airflow backflows and causes the impeller of the fan gearbox to reverse, the speed sensor detects that the speed is not 0. In the reverse state, the machine cannot pump oil. If the electric pump cannot be started in time, there will be a lack of lubrication between the shaft and the sliding bearing bush, which will cause the bearing to burn out.

[0031] The control system detects an abnormal situation where the equipment operation signal is 0, but the speed signal is not 0. Based on the logic, it determines that the fan is in reverse. The control system starts the electric pump 8 to provide lubricating oil. The fan gears are adequately lubricated to ensure that important components such as shafts, bearings, and gears are not damaged. At the same time, the system interface pops up an alarm message and outputs a reverse fault message, reminding the operation and maintenance personnel to go and confirm the actual situation on site and completely close the pipeline valves. After the valves are closed, the fan speed drops to 0, and the electric pump runs for 2 to 10 minutes before automatically shutting down.

[0032] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for preventing damage to a fan from reverse rotation, characterized in that: Includes the following steps: (1) Install a speed sensor on the low-speed shaft end cover of the wind turbine gearbox to monitor the speed of the low-speed shaft of the gearbox in real time and output the speed signal; (2) Input the speed signal output by the speed sensor and the operating signal of the fan into the control system; (3) When the control system determines that the fan's operating signal is 0 and the speed signal is not 0, it determines that the fan is in reverse rotation. (4) In the reverse state, the control system automatically starts the electric pump to provide lubricating oil to the sliding bearing of the fan gearbox, and at the same time the control system issues an alarm message; (5) After the maintenance personnel close the valve to the correct position, the speed of the low-speed shaft of the gearbox drops to 0, and the electric pump automatically shuts off after running for a period of time.

2. The method for preventing damage to a fan by reverse rotation according to claim 1, characterized in that: The speed sensor is mounted on the low-speed shaft end cover via a sensor bracket, which is fixed to the low-speed shaft end cover with bolts. The distance between the probe of the speed sensor and the surface of the coupling is adjusted by a nut.

3. The method for preventing damage to a fan by reverse rotation according to claim 1, characterized in that: The speed sensor is an electromagnetic induction sensor that measures the speed of the low-speed shaft of the gearbox by measuring the change in magnetic flux caused by a small hole on the coupling.

4. The method for preventing damage to a fan by reverse rotation according to claim 1, characterized in that: The bearings inside the wind turbine gearbox are sliding bearings, and are supplied with oil by a mechanical pump during normal operation and by an electric pump during reverse operation.

5. The method for preventing damage to a fan by reversing its rotation according to claim 1, characterized in that: The control system records the reversal fault information while issuing an alarm message.

6. The method for preventing damage to a fan by reverse rotation according to claim 1, characterized in that: The electric pump will automatically shut down after running for 2 to 10 minutes after the fan speed drops to 0.

7. A system for preventing fan reverse rotation damage in implementing the method of any one of claims 1-6, characterized in that: The system includes a drive motor, a fan gearbox, a speed sensor for monitoring the speed of the low-speed shaft of the gearbox, a control system, and an oil pump system. The drive motor is connected to the low-speed shaft of the fan gearbox via a coupling. The speed sensor is mounted on the end cover of the low-speed shaft of the fan gearbox. The control system is connected to the drive motor, the speed sensor, and the oil pump system.

8. The system for preventing damage to a fan from reverse rotation according to claim 7, characterized in that: The coupling has a small hole, and the probe of the speed sensor is positioned directly above the small hole.

9. A system for preventing damage to a fan by reverse rotation according to claim 7, characterized in that: The oil pump system includes an electric pump and a mechanical pump, which are respectively connected to the control system. The electric pump and the mechanical pump provide lubricating oil to the fan gearbox.

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