A DC brushless fan for cryogenic refrigerators

Abstract

This invention discloses a DC brushless fan for cryogenic refrigerators, belonging to the field of refrigerator motors. Addressing the problem that existing DC brushless fans struggle to operate normally at ultra-low temperatures, this invention provides a DC brushless fan for cryogenic refrigerators, including a motor mounted on a base, fan blades connected to the motor's output shaft, and a control board and a heating element sequentially arranged between the motor and the base. The control board controls the motor's operation to achieve closed-loop speed control, and the heating element heats the electronic components on the control board, which are located on the surface of the control board near the heating element. By using a heating element to heat the electronic components on the control board, this invention enables the DC brushless fan to deliver refrigerant air within an operating environment ranging from -40℃ to -60℃ while simultaneously allowing the electronic components on the control board to operate normally. The chip on the control board implements closed-loop speed control, ensuring that the fan speed remains at room temperature even in ultra-low temperature environments.

Description

Technical Field

[0001] This invention belongs to the field of refrigerator motor technology, and more specifically, relates to a DC brushless fan for cryogenic refrigerators. Background Technology

[0002] With increasing refrigeration demands, there is a growing need for specialized refrigerators requiring cooling temperatures between -40℃ and -60℃. Previously, only direct cooling or AC fan-based air cooling methods were available, resulting in significant energy losses. Using DC brushless fans for air cooling can reduce energy consumption by approximately 5% of the overall refrigerator energy consumption. Furthermore, the structure of DC brushless fans is significantly smaller than that of AC fans, reducing the volume by about 50%. This simplifies the refrigerator's air duct design, increasing overall storage capacity. The speed control function of DC brushless fans is also simple, allowing for stepless speed adjustment and effective distribution of airflow. Therefore, given the increasing demand for improved energy efficiency and diversified product functions, the need for DC brushless fans in deep-freeze refrigerators is growing. Existing brushless DC fans all require a drive circuit to operate normally. This drive circuit uses semiconductor chips, but the normal operating temperature range of existing semiconductor chips is only -40℃ to 105℃. When the low temperature range exceeds the chip's normal operating range, the motor drive circuit cannot guarantee the normal operation of the brushless DC fan, resulting in poor starting or unstable operation. Furthermore, existing brushless DC fans used in air-cooled refrigerators, for cost and structural simplification reasons, use oil-impregnated bearings as the bearings for the fan rotor shaft. The fit between the oil-impregnated bearing and the rotor shaft is a rolling friction relationship, with a certain clearance of about 15µm. In deep-cold conditions, due to the different shrinkage ratios of the shaft and bearing, the clearance between them decreases, and the friction coefficient increases accordingly. This leads to a significant decrease in the fan speed under deep-cold conditions. Current tests show that with traditional open-loop drive methods, the speed decrease can reach 50% at -60℃. This results in a significant reduction in the actual airflow from the refrigerator.

[0003] To address the aforementioned issues, corresponding improvements have been made. For example, Chinese patent application CN201710859535.8, published on February 23, 2018, discloses a permanent magnet DC brushless fan, including a base assembly, a fan blade assembly, a stator assembly, a rotor assembly, and a drive circuit board assembly. The base assembly includes bearings, retaining rings, a small circular base, and a large circular base. The fan blade assembly includes fan blades, a rotating shaft, and a bushing. The stator assembly includes winding terminals, an upper plastic frame, a stator core, and a lower plastic frame. The rotor assembly includes a magnetic ring and an iron ring. The magnetic ring is fixed inside the iron ring, and the iron ring is embedded in a groove in the center of the fan blade. After the stator assembly and the drive circuit board assembly are connected, they are fitted onto the outside of a hollow cylinder protruding at the center of the small base. The drawback of this patent is that although it effectively reduces energy consumption, the brushless fan as a whole is still significantly affected by temperature.

[0004] For example, Chinese patent application CN202210015691.7, published on March 8, 2022, discloses a DC brushless fan operating at -50 degrees Celsius. The fan includes a housing with an opening on the front and a side door. A mounting groove is located on the left side of the housing, and a fan body is housed within the housing's inner cavity. The left side of the fan body extends through the mounting groove to the left side of the housing. Mounting mechanisms are located on the right side of the fan body near the top and bottom. A junction box is adhered to the right side of the inner wall of the housing. The drawback of this patent is that while external circuitry is unaffected by low temperatures, it is susceptible to interference, resulting in overall unstable operation. Summary of the Invention

[0005] 1. The problem to be solved

[0006] To address the problem of existing brushless DC fans failing to operate normally at extremely low temperatures, this invention provides a brushless DC fan for cryogenic refrigerators. This invention uses heating elements to heat the electronic components on the control board, enabling the brushless DC fan to deliver cooling air within an environment ranging from -40℃ to -60℃ while simultaneously allowing the electronic components on the control board to function normally. The chip on the control board implements closed-loop speed control, ensuring that the fan speed remains at room temperature even in extremely low-temperature environments.

[0007] 2. Technical Solution

[0008] To solve the above problems, the present invention adopts the following technical solution.

[0009] A DC brushless fan for a cryogenic refrigerator includes a motor mounted on a base, fan blades connected to the output shaft of the motor, and a control board and a heating element arranged sequentially between the motor and the base. The control board is used to control the operation of the motor to achieve closed-loop speed control, and the heating element is used to heat the electronic components on the control board. The electronic components are mounted on the surface of the control board near the heating element.

[0010] Furthermore, the heating element includes a circular body that is attached to the base, and the body has a U-shaped heating circuit inside, which is connected to a power source.

[0011] Furthermore, the base has a circular mounting groove at its center, and a bearing for connecting to the motor is located at the center of the mounting groove. Several protrusions are evenly spaced along the circumference of the mounting groove. The main body has a circular hole at its center, the size of which is larger than the size of the bearing. Several grooves are evenly spaced along the circumference of the main body. The connection between the base and the heating element is achieved through the cooperation of the grooves and the protrusions.

[0012] Furthermore, a thermally conductive silicon wafer is filled in the gap between the heating element and the control board, and the thermally conductive silicon wafer covers the entire surface of the control board.

[0013] Furthermore, the control board includes a Hall effect detection element for converting the sampled frequency of the N and S pole changes of the motor rotor into a differential signal;

[0014] The actual rotational speed sampling circuit, which is electrically connected to the Hall effect sensor, is used to compare and amplify the sampled rotational speed frequency signal, convert it into a level signal, and then into a digital signal.

[0015] The comparison and analysis circuit connected to the actual speed sampling circuit is used to convert the actual speed and the target speed into a numerical signal.

[0016] The target speed setting circuit, connected to the comparison and analysis circuit, is used to convert the set target speed into a digital signal; the target speed setting circuit is connected to an external PWM Duty signal and an RT resistor value configuration.

[0017] An active clamping circuit connected to the comparison analysis circuit is used to reduce or increase the 12V supply current based on the comparison signal.

[0018] The 12VDC power supply connected to the active clamping circuit is used to provide a 12V DC voltage to the active clamping circuit first.

[0019] H-bridge arm circuit connected to active clamping circuit: used for control of the current applied to the motor stator coil by the MOSFET of H-bridge under active clamping circuit control.

[0020] Furthermore, the maximum target speed in the target speed setting circuit is 60. K Vsp÷(Rt P 16 10³), where K is the motor speed parameter; Vsp is the maximum effective value of the Vsp pin voltage of the chip; Rt is the parallel equivalent resistance of the two resistors in the chip circuit.

[0021] Furthermore, the fan blade includes a housing, an inner hub is provided on the housing, and a plurality of blades are provided between the housing and the inner hub. The inner hub is connected to the output shaft of the motor.

[0022] Furthermore, the blade includes a blade root connected to the outer casing, and a blade tip is provided at the end of the blade root away from the outer casing extending inward toward the inner hub. The width of the blade tip gradually narrows from the direction of the blade root toward the direction of the inner hub.

[0023] 3. Beneficial effects

[0024] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0025] (1) This invention heats the electronic components on the control board by setting a heating element, so that the brushless DC fan can deliver refrigerated air in the working environment of -40℃ to -60℃, while the electronic components on the control board can work normally, so that the drive of the brushless DC fan can work normally in the ultra-low temperature environment; at the same time, the closed-loop speed control function is realized by the chip on the control board, eliminating the large-scale speed reduction caused by the change of the friction coefficient of the bearing and shaft in the deep cold state, ensuring that the speed remains at the normal temperature state in the ultra-low temperature environment; the overall structure is simpler than the direct cooling method; compared with AC fan, the motor unit structure is simplified and the volume is reduced; it can achieve stable and normal operation in the ultra-low temperature environment;

[0026] (2) The present invention sets the heating element as a circle, which has a larger area than other shapes. The circular shape makes it easy to fit tightly to the base for a secure connection. At the same time, a heating circuit is set inside the circular body. The U-shaped heating circuit can evenly cover the inside of the body, so that the body can be heated relatively evenly. Meanwhile, the base and the heating element are fitted together by grooves and protrusions to ensure stability while fitting tightly to the base, preventing the heating element from falling off or loosening due to interference from the external environment, thus ensuring the stability of the heating element. In addition, the circular hole in the center of the heating element can avoid the bearing on the base, ensuring that the installation is free of interference.

[0027] (3) The present invention provides a thermally conductive silicon sheet between the heating element and the control board. Since there is a gap of about 2mm between the heating element and the control board, air will circulate in this gap. Therefore, the gap is filled with a thermally conductive silicon sheet, and the thermally conductive silicon sheet covers the entire control substrate and wraps around each electronic component, so that the heat generated by the thin film heating element can be smoothly transferred to the electronic components on the control board, further ensuring the heat transfer effect and ensuring that the heat generated by the heating element can be transferred to the electronic components on the control board through the thermally conductive silicon sheet, so that they can maintain normal operation in an ultra-low temperature environment.

[0028] (4) In this invention, the LA6220H chip is selected. This chip is a single-phase brushless motor drive chip with closed-loop speed control function. The target speed can be set by setting the resistance value externally. At this time, the target speed is not affected by the change of the friction coefficient of the bearing and shaft. The target speed is also not affected by the change of the air density in the refrigerator in the cold state. Compared with AC fans, it realizes simpler speed adjustment or even stepless speed regulation. And the corresponding working principle is realized by the corresponding circuit on the control board, so that the DC brushless fan can maintain the speed at room temperature even at an ambient temperature of -60℃.

[0029] (5) The fan blade in this invention is composed of a shell, an inner hub and blades. The blades are placed between the shell and the inner hub to effectively protect the blades and prevent them from being directly exposed and easily damaged by external interference, thus improving the service life of the blades. At the same time, the blades are composed of blade roots and blade tips. The structure of the blades is optimized to conform to aerodynamics, enhance the suction force and improve efficiency. Furthermore, the setting of the blade tip increases the suction capacity of the blades and effectively improves the air volume of the fan of the same size and specifications. Attached Figure Description

[0030] Figure 1 This is a three-dimensional structural diagram of the present invention;

[0031] Figure 2 This is an exploded view of the present invention;

[0032] Figure 3 This is an assembly diagram of the present invention;

[0033] Figure 4 This is a schematic diagram of the circuit in which the LA6220H is used in this invention;

[0034] Figure 5 This is a schematic diagram illustrating the circuit module in this invention.

[0035] Figure 6 This is a linear relationship diagram of the PWM duty cycle (Duty) in this invention corresponding to the maximum target speed of 1600 RPM.

[0036] In the diagram: 1. Fan blade; 2. Motor; 3. Control board; 4. Thermal conductive silicon wafer; 5. Heating element; 6. Base. Detailed Implementation

[0037] The present invention will now be further described with reference to specific embodiments and accompanying drawings.

[0038] Example 1

[0039] like Figure 1 , Figure 2 and Figure 3 As shown, a DC brushless fan for a cryogenic refrigerator includes a motor 2 mounted on a base 6, fan blades 1 connected to the output shaft of the motor 2, and a control board 3 and a heating element 5 sequentially arranged between the motor 2 and the base 6. Figure 2 For example, from left to right, the components are: fan blade 1, motor 2, control board 3, heating element 5, and base 6. The control board 3 is used to control the motor 2 to achieve closed-loop speed control. Specifically, the control board 3 is equipped with a domestically produced LA6220H chip and other electronic components. The LA6220H chip is a single-phase brushless motor driver chip with closed-loop speed control function. It can set the target speed by externally setting the resistance value. Using the LA6220H chip, if the rated target speed is set to 1600 RPM, the motor speed is adjusted through PWMDuty. The PWM speed corresponding to 0%~100% duty range (0 RPM~1600 RPM) has a constant linear relationship, as shown in the diagram. Figure 6 As shown, when PWMDuty decreases, the corresponding current target speed equals the maximum set target speed. Duty cycle value. The target rotational speed is unaffected by changes in the friction coefficients of the bearings and shaft, and also unaffected by changes in air density within the refrigerator compartment under cold conditions. The circuit diagram of the LA6220H chip is shown below. Figure 4 As shown, its circuit can realize closed-loop speed control function, and it should be noted here that... Figure 4 The equivalent resistance of the parallel connection of resistors R10 and R11 in the diagram is called the RT resistor.

[0040] Meanwhile, the connections between the domestically produced chip LA6220H on control board 3 and other electronic components form the following circuit: (e.g.) Figure 5As shown, the control board 3 includes a Hall effect sensor: used to convert the sampled frequency of the motor rotor's N / S pole changes into a differential signal; when the rotor of motor 2 rotates, the N / S magnetic poles resting on the Hall effect sensor change, and then the frequency change is converted into a differential signal and transmitted to the actual speed sampling circuit; the actual speed sampling circuit, electrically connected to the Hall effect sensor: used to compare and amplify the sampled speed frequency signal, convert it into a level signal, then into a digital signal, and then transmit the digital signal to the comparison and analysis circuit; the comparison and analysis circuit, connected to the actual speed sampling circuit: used to convert the actual speed and the target speed into a numerical signal based on the comparison; the target speed setting circuit (i.e., the maximum speed target setting, the linear relationship circuit between the PWM signal and the target speed), connected to the comparison and analysis circuit: used to convert the set target speed into a digital signal; the target speed setting circuit is connected to the external PWM Duty signal and the RT resistor value configuration respectively, and realizes the current target speed adjustment of the brushless DC motor through the PWM interface and the command change of the external PWM Duty; specifically, the maximum target speed in the target speed setting circuit is 60. K Vsp÷(Rt P 16 10³), where K is the speed parameter of motor 2; Vsp is the maximum effective value of the Vsp pin voltage of the chip; Rt is the equivalent parallel resistance of the two resistors R10 and R11 in the chip circuit; therefore, the maximum target speed can be adjusted by adjusting the resistance value of Rt; the active clamping circuit connected to the comparison analysis circuit: used to reduce or increase the 12V supply current according to the comparison signal; the 12VDC power supply connected to the active clamping circuit: used to provide 12V DC voltage first input to the active clamping circuit; the H-bridge arm circuit connected to the active clamping circuit: used to control the current loaded on the stator coil of the motor by the MOSFET of the H-bridge under the control of the active clamping circuit; the current flowing through the stator coil of the motor generates an excitation magnetic field, and the demagnetized rotor rotates to realize the drive of motor 2.

[0041] By using different circuits on control board 3 to operate in different ways, the DC brushless fan maintains its normal operating speed even at an ultra-low temperature of -60℃. The inventors also verified that, under a non-closed-loop speed control scheme, a DC brushless fan with a rated speed of 1570 RPM at room temperature actually operates at 978 RPM at -60℃. By employing the LA6220H driver chip, a DC brushless fan with a normal operating speed of 1600 RPM (speed fluctuation range ±50 RPM) maintains its normal operating speed even at -60℃, thus enabling the application of the DC brushless fan for cold air delivery in cryogenic refrigerators (-40℃ to -60℃).

[0042] Furthermore, in this embodiment, the heating element 5 is used to heat the electronic components on the control board 3. These electronic components are located on the surface of the control board 3 near the heating element 5. Since the electronic components on the control board 3 cannot function properly in an environment of -40℃ to -60℃, heating them in reverse ensures that the overall operating environment of the brushless DC fan is within the range of -40℃ to -60℃, allowing it to deliver cooling air in a refrigerator. However, the local surface temperature of the electronic components on the control board 3 is higher than -40℃, enabling the brushless DC motor drive system to operate normally. Specifically, the heating element 5 includes a circular body that fits onto the base 6. The body contains a U-shaped heating circuit connected to a power source. The outlet of the heating circuit matches the wiring harness outlet of the base 6 of the brushless DC fan, allowing both the heating element 5 and the control board 3 to be powered by an external 12V power supply. The heating circuit inside the main body is powered by 12V DC voltage with a power of 3W. The shape of the main body fits the shape of the base 6, which makes it easy to stick to the base 6 and achieve a stable connection. The circular shape of the main body has a larger area than other shapes, and the circular shape makes it easy to stick to the base 6 and achieve a tight connection. At the same time, the U-shaped heating circuit is set inside the circular main body so that it can evenly cover the inside of the main body, so that the main body can be heated more evenly, further ensuring the heating effect and heat transfer effect.

[0043] This invention heats the electronic components on the control board 3 using heating elements 5, enabling the brushless DC fan to deliver cooled air within an operating environment of -40℃ to -60℃ while simultaneously allowing the electronic components on the control board 3 to function normally. This ensures the brushless DC fan can operate normally in ultra-low temperature environments. Furthermore, the chip on the control board 3 implements closed-loop speed control, eliminating the significant speed reduction caused by changes in the friction coefficient of the bearings and shaft in cryogenic conditions. This ensures that the speed remains at room temperature even in ultra-low temperature environments. Overall, the structure is simpler than direct cooling methods; compared to AC fans, the motor unit structure is simplified and its size is reduced; and it can achieve stable and normal operation in ultra-low temperature conditions.

[0044] Example 2

[0045] Similar to Embodiment 1, to further ensure heat transfer efficiency and the normal operation of electronic components on the control board 3, a circular mounting groove is provided in the center of the base 6 in this embodiment. A bearing connected to the motor 2 is located in the center of the mounting groove, and several protrusions are evenly spaced along the circumference of the mounting groove. A circular hole, larger than the bearing, is provided in the center of the main body, and several grooves are evenly spaced along the circumference of the main body. The connection between the base 6 and the heating element 5 is achieved through the cooperation of the grooves and protrusions. The base 6 and the heating element 5 are secured to the base 6 while maintaining stability through the cooperation of the grooves and protrusions, preventing the heating element 5 from falling off or loosening due to external environmental interference, thus ensuring the stability of the heating element 5. Furthermore, the circular hole in the center of the heating element 5 avoids interference with the bearing on the base 6, ensuring interference-free installation.

[0046] In this embodiment, a thermally conductive silicon wafer 4 is filled in the gap between the heating element 5 and the control board 3. The thermally conductive silicon wafer 4 covers the entire surface of the control board 3. It should be noted that because there is a gap of approximately 2mm between the control board 3 and the heating element 5, air will flow through this gap. Since the fan itself operates in a cryogenic environment, and the DC brushless fan is not a sealed structure, external cold air will flow into this gap, preventing the heat generated by the heating element 5 from being effectively conducted to the surface of the electronic components on the control board 3. Therefore, in this embodiment, the gap between the heating element 5 and the control board 3 is filled with a thermally conductive silicon wafer 4, which covers the entire control board 3, enveloping each electronic component on the control board 3. This ensures that the heat generated by the heating element 5 is smoothly transferred to the electronic components on the control board 3, thereby guaranteeing the normal operation of the electronic components in an ultra-low temperature environment. The inventors have confirmed through experiments that at room temperature (25℃), using this method, the surface temperature of the control board 3 is maintained at approximately 75℃, and at a cryogenic temperature of -60℃, the surface temperature of the control board 3 is approximately -36℃. The temperatures in both states are within the normal operating temperature range of the electronic components. When the DC brushless fan of this application is applied in a cryogenic refrigerator, compared to direct cooling, it has a simpler structure and eliminates the problem of frost buildup. Compared to AC fans, the individual motor structure is simplified and its size is reduced. This reduction in size simplifies the refrigerator's air duct structure, allowing for a larger internal storage capacity for refrigerators of the same size. Furthermore, the energy efficiency of the individual motor is improved by approximately 37%. (A conventional AC motor with an airflow requirement of 1.5 m³ / min requires approximately 8W of input power, while a DC brushless fan with the same airflow output requires approximately 2W of input power, plus the 3W power of the heating element 5). Compared to AC fans, speed adjustment, and even stepless speed regulation, can be achieved more easily.

[0047] In this embodiment, the fan blade 1 includes a housing with an inner hub. Several blades are arranged between the housing and the inner hub. The inner hub is connected to the output shaft of the motor 2. Positioning the blades between the housing and the inner hub prevents them from being directly exposed and susceptible to damage from external interference, thus extending their service life. Specifically, each blade includes a blade root connected to the housing. A blade tip extends from the end of the blade root away from the housing towards the inner hub. The width of the blade tip gradually narrows from the blade root towards the inner hub, optimizing the blade structure for aerodynamic purposes, enhancing suction power, and improving efficiency. The blade tip also increases the blade's suction capacity, effectively increasing the airflow of a fan of the same size. Additionally, a spiral groove is provided on the inner wall of the housing, positioned between adjacent blades along the blade's twisting direction. This spiral groove serves to guide airflow, further reducing resistance and minimizing vibration and noise of the entire fan blade 1.

[0048] The examples described herein are merely preferred embodiments of the invention and are not intended to limit the concept and scope of the invention. Any modifications and improvements made by those skilled in the art to the technical solutions of the invention without departing from the design concept of the invention should fall within the protection scope of the invention.

Claims

1. A DC brushless fan for a cryogenic refrigerator, comprising a motor (2) mounted on a base (6), wherein fan blades (1) are connected to the output shaft of the motor (2), characterized in that: A control board (3) and a heating element (5) are arranged sequentially between the motor (2) and the base (6). The control board (3) is used to control the operation of the motor (2) to achieve closed-loop speed control. The heating element (5) is used to heat the electronic components on the control board (3). The electronic components are arranged on the surface of the control board (3) near the heating element (5). The control board (3) includes a Hall effect detection element: used to convert the sampled frequency of the motor rotor's N and S poles into a differential signal; The actual rotational speed sampling circuit, which is electrically connected to the Hall effect sensor, is used to compare and amplify the sampled rotational speed frequency signal, convert it into a level signal, and then into a digital signal. The comparison and analysis circuit connected to the actual speed sampling circuit is used to convert the actual speed and the target speed into a numerical signal. The target speed setting circuit, connected to the comparison and analysis circuit, is used to convert the set target speed into a digital signal; the target speed setting circuit is connected to an external PWM Duty signal and an RT resistor value configuration. An active clamping circuit connected to the comparison analysis circuit is used to reduce or increase the 12V supply current based on the comparison signal. The 12VDC power supply connected to the active clamping circuit is used to provide a 12V DC voltage to the active clamping circuit first. H-bridge arm circuit connected to active clamping circuit: used for control by active clamping circuit, the current loaded onto the motor stator coil by the MOSFET of H-bridge is controlled; The maximum target speed in the target speed setting circuit is 60. K Vsp÷(Rt P 16 10³), where K is the motor speed parameter; Vsp is the maximum effective value of the Vsp pin voltage of the chip; Rt is the parallel equivalent resistance of the two resistors in the chip circuit.

2. A DC brushless fan for a cryogenic refrigerator according to claim 1, characterized in that: The heating element (5) includes a circular body that is attached to the base (6) and has a heating circuit in the shape of a "U" inside the body, which is connected to a power source.

3. A DC brushless fan for a cryogenic refrigerator according to claim 2, characterized in that: The base (6) has a circular mounting groove in the center, and a bearing connected to the motor (2) is set in the center of the mounting groove. Several protrusions are set at equal intervals along the circumference of the mounting groove. The body has a circular hole in the center, the size of which is larger than the size of the bearing. Several grooves are set at equal intervals along the circumference of the body. The connection between the base (6) and the heating element (5) is achieved through the cooperation of the grooves and the protrusions.

4. A DC brushless fan for a cryogenic refrigerator according to claim 1 or 2, characterized in that: A thermally conductive silicon wafer (4) is filled in the gap between the heating element (5) and the control board (3), and the thermally conductive silicon wafer (4) covers the entire surface of the control board (3).

5. A DC brushless fan for a cryogenic refrigerator according to claim 1, characterized in that: The fan blade (1) includes a housing, an inner hub is provided on the housing, and several blades are provided between the housing and the inner hub. The inner hub is connected to the output shaft of the motor (2).

6. A DC brushless fan for a cryogenic refrigerator according to claim 5, characterized in that: The blade includes a blade root, which is connected to the outer shell. The end of the blade root away from the outer shell extends inward toward the inner hub and is provided with a blade tip. The width of the blade tip gradually narrows from the direction of the blade root toward the direction of the inner hub.

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