A centrifugal fan with adjustable impeller outer diameter

Abstract

This invention discloses an adjustable impeller outer diameter impeller, including a mounting bracket, a housing and an impeller motor fixed on the mounting bracket, and a blade adjustment device. The blade adjustment device includes a movable blade mounted at the blade outlet of a stationary blade, the movable blade being flush with the surface of the stationary blade and maintaining a relative sliding fit with it, the width of the movable blade being the same as the width of the stationary blade; and a guide device for limiting the extension or retraction of the movable blade along the outlet angle direction of the stationary blade. By extending or retracting the movable blade along the outlet direction of the stationary blade, the blade size changes, thereby adjusting the flow parameters of the centrifugal fan to adapt to temporary or variable operational needs and improve the overall efficiency of the centrifugal fan. Furthermore, it eliminates the need for a frequency converter or throttle valve at the fan inlet to control the fan flow parameters, thus saving costs and ensuring fan efficiency.

Description

TECHNICAL FIELD

[0001] The present application relates to a centrifugal fan, in particular to a centrifugal fan with adjustable impeller outer diameter. BACKGROUND

[0002] A centrifugal fan is a machine that relies on input mechanical energy to increase the pressure of a gas and to deliver it, and it is a driven fluid machine. The centrifugal fan is widely used for ventilation, dust removal and cooling in factories, mines, tunnels, cooling towers, vehicles, ships and buildings; ventilation and air induction for boilers and industrial furnaces; cooling and ventilation in air conditioning equipment and household appliances; grain drying and selection; wind tunnel air source and air cushion boat inflation and propulsion, etc.

[0003] There are two common types of fans in industry: centrifugal fans and axial flow fans. Compared with axial flow fans, centrifugal fans can produce higher pressure rise. Both types of fans usually need the ability to adjust the flow parameter according to the change in flow or pressure. In centrifugal fans, the most common method of adjustment is to use a frequency converter or a throttle valve at the fan inlet to control the flow parameter of the fan, the former method is effective but expensive, especially for large fans, and the latter method significantly reduces fan efficiency. SUMMARY

[0004] In order to overcome the shortcomings of the prior art, the present application provides a centrifugal fan that can change the length of the impeller outer diameter to adjust the flow parameter of the fan.

[0005] The technical scheme adopted by the present application to solve its technical problems is: a centrifugal fan with adjustable impeller outer diameter, comprising a mounting frame, an impeller and an impeller motor fixed on the mounting frame, the impeller comprising a front disc, a rear disc, and a static blade mounted between the front disc and the rear disc, the impeller motor being linked to the static blade through an output shaft, characterized in that: it further comprises a blade adjusting device, the blade adjusting device comprising,

[0006] a moving blade mounted at the blade outlet portion of the static blade, the moving blade being arranged in close contact with the surface of the static blade and in relative sliding fit with the static blade, the width of the moving blade being consistent with the width of the static blade;

[0007] a guide device for limiting the extension or retraction of the moving blade along the outlet angle direction of the static blade.

[0008] The beneficial effects of this invention are as follows: By setting a moving blade at the outlet of the stationary blade, and having the moving blade extend or retract along the outlet direction of the stationary blade, the blade size composed of the stationary and moving blades changes, thereby adjusting the flow parameters of the centrifugal fan to adapt to temporary or variable operational needs and improve the overall working efficiency of the centrifugal fan. Furthermore, it eliminates the need for a frequency converter or throttle valve at the fan inlet to control the fan flow parameters, thus saving costs and ensuring fan efficiency.

[0009] The device is further configured such that the edges of the moving blade corresponding to the positions of the front and rear discs are side edges, and the guiding device includes: guide grooves respectively formed on the front and rear discs for inserting the side edges of the moving blade, with the side edges of the moving blade slidingly engaging with the guide grooves; and a limiting mechanism to prevent the moving blade from disengaging from the guide grooves. The guide grooves limit the direction of movement of the moving blade, while the limiting mechanism ensures that the moving blade and the guide groove remain relatively stable.

[0010] The limiting mechanism is further configured as follows: Vertical guards protrude from both sides of the guide groove opening on the rear disc; horizontal guards extend towards the center from the openings of the two vertical guards; a guide space is formed between the two vertical guards; and a gap is provided between the two horizontal guards. A side of the moving blade, inserted into the guide groove of the rear disc, extends into the guide space. A guide block protrudes from this side and slides within the guide space; the size of the guide block is larger than the gap size. The guide block prevents the moving blade from detaching from the guide groove, ensuring relative stability between the moving blade and the guide groove.

[0011] The guide device is further configured to include a drive mechanism for driving each guide block to slide within the guide space. This drive mechanism includes: a driven wheel and a collar rotatably mounted on the output shaft of the impeller motor, the driven wheel and collar being concentrically arranged and fixed to each other; a pull rod matching the number of moving blades, one end of which is located at the gap in the guide space and has a rotating shaft that rotatably engages with it, extending into the guide space and rotatably engaging with the guide block; the other end extends to the collar and rotatably engages with it; the portions of each pull rod connected to the collar are evenly distributed circumferentially around the collar; and a guide motor fixed to the mounting bracket, the output shaft of which has a driving wheel, the driving wheel and the driven wheel being connected by a transmission belt. By starting the guide motor and reversing it, the collar rotates in both directions, thereby driving the pull rods to rotate with the guide blocks within the guide space, thus achieving blade size adjustment. The impeller and the collar maintain a sufficient distance to prevent interference between their movements. By changing the relative position of the movable blades and the fixed blades themselves, the impeller's outer diameter can be adjusted as needed while keeping the inner diameter constant. This allows for better adjustment of the centrifugal fan's flow parameters to adapt to temporary or variable operating conditions, thereby improving the fan's efficiency. Furthermore, the impeller motor and guide motor rotate synchronously. When blade size adjustment is required, simply increasing or decreasing the rotation speed of the guide motor achieves the adjustment. This operation is particularly suitable for applications with high requirements for centrifugal fans, allowing for blade size adjustment without shutting down the system.

[0012] The guide device is further configured to include a drive mechanism for driving each guide block to slide within the guide space. This drive mechanism includes: a collar fitted onto the output shaft of the impeller motor, the collar having a through hole extending to the impeller motor output shaft, and an adjusting bolt for fastening the collar and the impeller motor output shaft at the through hole; and a pull rod matching the number of moving blades, one end of which is located at the gap in the guide space and has a rotating shaft that rotates with it, extending into the guide space and rotating with the guide block; the other end extends to the collar and rotates with the collar. The portions of the pull rods connected to the collar are evenly distributed circumferentially around the collar. By manually rotating the collar, the pull rods drive the moving blades to extend or retract along the exit direction of the stationary blades. The entire process can be manually operated. Although this reduces timeliness, it reduces the number of required equipment, resulting in low-cost operation and improved cost-effectiveness in some low-requirement working environments.

[0013] A further configuration is made where the material density of the moving blade is lower than that of the stationary blade. The lower-density stationary blade, while meeting operational requirements, improves the overall cost-effectiveness. Attached Figure Description

[0014] Figure 1This is a schematic diagram of the structure of Embodiment 1 of the present invention.

[0015] Figure 2 This is a schematic diagram of the impeller structure in Embodiment 1 of the present invention.

[0016] Figure 3 This is a schematic diagram of the structure of an impeller combined with a driving wheel, a driven wheel, and a transmission belt according to an embodiment of the present invention.

[0017] Figure 4 This is a cross-sectional view of the impeller in Embodiment 1 of the present invention.

[0018] Figure 5 This is a structural schematic diagram of the impeller rear disc from the perspective of Embodiment 1 of the present invention.

[0019] Figure 6 for Figure 4 Enlarged view of part A.

[0020] Figure 7 This is a schematic diagram of the structure of Embodiment 1 of the present invention, viewed from above.

[0021] Figure 8 The equation represents the flow characteristics of a centrifugal fan. Detailed Implementation

[0022] The present invention will now be further described with reference to the accompanying drawings:

[0023] The flow parameters of a centrifugal fan include flow rate and pressure rise. For example... Figure 7 The equations shown describe the relationship between the flow rate and pressure rise of a centrifugal fan and the impeller size, where V1 is the fan flow rate for an impeller with an outer diameter of D1, V2 is the fan flow rate for an impeller with an outer diameter of D2, Δp1 is the fan pressure rise for an impeller with an outer diameter of D1, and Δp2 is the fan pressure rise for an impeller with an outer diameter of D2. It is noteworthy that there is a third-order relationship between the fan flow rate and the impeller outer diameter. Similarly, there is a second-order relationship between the pressure rise and the impeller outer diameter. From the above equations, it can be seen that a relatively small change in the impeller diameter will significantly affect the fan flow rate and pressure rise. Therefore, it can be concluded that this method can serve as a new and effective way to define the flow rate parameters of a centrifugal fan, namely, by adjusting the impeller blade length, the outer diameter can be modified.

[0024] Example 1: As Figures 1-7As shown, this embodiment includes a mounting frame, an impeller 1 and an impeller motor 6 fixed on the mounting frame. The impeller 1 includes a front disc 14, a rear disc 13, and stationary blades 12 installed between the front disc 14 and the rear disc 13. The impeller motor 6 is linked to the stationary blades 12 via an output shaft 4. The mounting frame includes a fixed bracket 10, a vibration damping platform 9, and a protective plate 8. The fixed bracket 10 and the vibration damping platform 9 are fastened together, the vibration damping platform 9 is fastened to the ground, and the protective plate 8 is fastened to the vibration damping platform 9. The protective plate 8 is used to isolate the impeller 1 and the impeller motor 6. In addition, a moving blade 11 is also installed on the mounting frame. The moving blade 11 is disposed close to the surface of the stationary blade 12 and maintains a relative sliding fit with the stationary blade 12. The width of the moving blade 11 is the same as the width of the stationary blade 12. A guide device is installed on the rear disc 13 to limit the extension or retraction of the moving blade 11 along the exit angle direction of the stationary blade 12. The edge of the moving blade 11 that contacts the front disc 14 and the rear disc 13 is called the side edge. The guiding device includes a guide groove 134 and a limiting mechanism. The guide groove 134 is respectively opened on the front disc 14 and the rear disc 13. The side edge of the moving blade 11 is inserted into the guide groove 134 and slides with the guide groove 134, thereby limiting the movement of the moving blade 11. The limiting mechanism 2 is used to prevent the moving blade 11 from disengaging from the guide groove 134. In this embodiment, the limiting mechanism 2 includes vertical guard edges 131 protruding on both sides of the opening of the guide groove 134 on the rear disc 13. The openings of the two vertical guard edges 131 are provided with horizontal guard edges 132 extending towards the center. A guiding space 133 is formed between the two vertical guard edges 132, and a gap is provided between the two horizontal guard edges 132. The moving blade 11 is inserted into the side of the guide groove 134 where the rear disc 13 is located and extends into the guide space 133. A guide block 111 protrudes from this side and slides within the guide space 133. The size of the guide block 111 is larger than the gap size. Figure 3 It can be seen that the vertical guard 131 in the limiting mechanism 2 is located on both sides of the guide groove 134 in the three-dimensional direction and is a guide rail 21 structure arranged along the length of the guide groove 134. The two horizontal guards 132 form the limiting structure on the upper part of the two guide rails 21, thereby restricting the guide block 111 from coming out of the gap.

[0025] In this embodiment, the guiding device further includes a driving mechanism for driving each guide block to slide within the guiding space. This driving mechanism includes a driven wheel 53 and a collar 32 rotatably mounted on the output shaft 4 of the impeller motor 6. The driven wheel 53 and the collar 32 are concentrically arranged and fixed to each other. The collar 32 and the output shaft 4 are rotated together via a bearing 54. A pull rod 31, matching the number of moving blades 11, has one end located at the gap in the guiding space 133 and equipped with a rotating shaft 135 that rotates with it. The rotating shaft 135 extends into the guiding space 133 and rotates with the guide block 111. The other end extends to the collar 32 and rotates with it. The portions of each pull rod 31 connected to the collar 32 are evenly distributed circumferentially around the collar 32. A guiding motor 7 is also fixed on the mounting frame. The output shaft of the guiding motor 7 is equipped with a driving wheel 51, and the driving wheel 51 and the driven wheel 53 are connected by a transmission belt 52. When the impeller motor 6 and guide motor 7 operate synchronously, adjusting the blade size is achieved simply by increasing or decreasing the rotation speed of the guide motor 7. This operation is particularly suitable for applications with high requirements for centrifugal fans, allowing for blade size adjustment without shutting down the system. The material density of the blades is lower than that of the stationary blades. The low-density stationary blades 12 not only meet operational requirements but also improve the overall cost-effectiveness. To improve synchronization, all motors are servo motors.

[0026] Example 2: The main difference from Example 1 lies in the guiding device. The guiding device also includes a driving mechanism for driving each guide block 111 to slide within the guiding space 133. The driving mechanism includes: a collar 32 sleeved on the output shaft 4 of the impeller motor 6. The surface of the collar 32 has a through hole extending to the output shaft 4 of the impeller motor 6. An adjusting bolt for fastening between the collar 31 and the output shaft 4 of the impeller motor 6 is provided at the through hole; a pull rod 31 matching the number of moving blades 11. One end of the pull rod 31 is located at the gap in the guiding space 133 and has a rotating shaft 135 that rotates with it. The rotating shaft 135 extends into the guiding space 133 and rotates with the guide block 111. The other end extends to the collar 32 and rotates with the collar 32. The parts of each pull rod 31 that connect to the collar 32 are evenly distributed around the collar 32. This embodiment eliminates the need for a guide motor, making the adjustment of the blade size a manual process. While this reduces timeliness, it also reduces the number of required devices, resulting in low-cost operation and improved cost-effectiveness in less demanding work environments.

Claims

1. An adjustable impeller outer diameter, comprising a mounting frame, an impeller and an impeller motor fixed on the mounting frame, the impeller comprising a front plate, a rear plate, and stationary blades mounted between the front plate and the rear plate, the impeller motor being linked to the stationary blades via an output shaft, characterized in that: The blade adjusting device comprises, a movable blade installed at a blade outlet position of the stationary blade, the movable blade being arranged close to the surface of the stationary blade and being in relative sliding fit with the stationary blade, the width of the movable blade being consistent with the width of the stationary blade; a guide device for limiting the movable blade from extending or retracting along the outlet angle direction of the stationary blade; the edges of the movable blade corresponding to the positions of the front disc and the rear disc are side edges, and the guide device comprises: guide grooves respectively provided on the front disc and the rear disc and used for inserting the side edges of the movable blade, the side edges of the movable blade being in sliding fit with the guide grooves; a limiting mechanism for preventing the movable blade from being separated from the guide grooves; the limiting mechanism comprises vertical blocking edges protruding from the guide groove on both sides of the rear disc, the opening of the two vertical blocking edges is provided with a horizontal blocking edge extending to the center, a guide space is formed between the two vertical blocking edges, and a gap is provided between the two horizontal blocking edges; the side edge of the movable blade inserted into the guide groove of the rear disc extends into the guide space, a guide block protruding from the side edge and sliding in the guide space is provided on the side edge, and the size of the guide block is greater than the size of the gap; the guide device further comprises a driving mechanism for driving each guide block to slide in the guide space, the driving mechanism comprises: a driven wheel and a sleeve ring rotatably sleeved on the output shaft of the impeller motor, the driven wheel and the sleeve ring are concentrically arranged and fixed to each other; a pull rod matched with the number of the movable blades, one end of the pull rod is located at the gap of the guide space and is provided with a rotating shaft in rotating fit with the pull rod, the rotating shaft extends into the guide space and is in rotating fit with the guide block, the other end of the pull rod extends to the sleeve ring and is in rotating fit with the sleeve ring, and the positions of the pull rods connected with the sleeve ring are uniformly distributed around the sleeve ring in the circumferential direction; a guide motor fixed to the mounting frame, the output shaft of the guide motor is provided with a driving wheel, and the driving wheel and the driven wheel are connected through a transmission belt.

2. The centrifugal fan of claim 1, wherein: The material density of the movable blade is lower than the material density of the stationary blade.

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