A box-type centrifugal fan with air intake adjustment function

Abstract

This invention discloses a box-type centrifugal fan with air intake adjustment function, including a box body, a centrifugal impeller, and a power mechanism. The centrifugal impeller is rotatably mounted inside the box body, and the power mechanism is mounted on the outside of the box body and is drivenly connected to the centrifugal impeller. The outer wall of the box body has an air inlet and an air outlet. A combined air inlet hood is installed at the air inlet, which includes an outer hood and an inner hood. The outer hood is fitted onto the outside of the inner hood, forming a main air inlet chamber between the outer and inner hoods. An auxiliary air inlet chamber is formed inside the inner hood. An air intake adjustment mechanism is installed on the outside of the inner hood. This invention designs a combined air inlet hood to form the main air inlet chamber and the auxiliary air inlet chamber. The main air inlet chamber is open, and the auxiliary air inlet chamber is autonomously controlled to open and close according to the negative pressure inside the box. This invention adjusts the size of the air intake area by using a combined air inlet hood, thereby adapting the fan equipment to use under different operating conditions.

Description

Technical Field

[0001] This invention relates to the field of fan equipment technology, and more specifically, to a box-type centrifugal fan with an air intake adjustment function. Background Technology

[0002] Box-type centrifugal fans are a major type of fan equipment, primarily used in building ventilation, fire smoke extraction, and industrial cooling applications. Most existing box-type centrifugal fans use a fixed-size inlet design, meaning the inlet is directly drilled into the outer wall of the casing, resulting in a fixed inlet area. While this design simplifies inlet fabrication, it also introduces limitations. The fan is only suitable for fixed operating conditions and cannot adapt to changes in the inlet area when environmental conditions change. For example, when a filter or activated carbon adsorption device is connected to the fan inlet, the internal resistance of the filter or activated carbon adsorption device (collectively referred to as filtration equipment) gradually increases over time (due to the filter screen becoming increasingly dirty), which will affect the changing operating environment of the fan. When the filtration equipment is in brand new condition, its internal resistance is at its lowest. A fixed, large-area air inlet can lead to excessively high airflow from the fan and a rapid decline in the filter's lifespan. In this case, a smaller air inlet is required. As the filtration equipment continues to operate, its internal resistance gradually increases, which causes a decrease in the fan's airflow. The fan can no longer maintain normal airflow. At this point, it is necessary to adjust and enlarge the air inlet area to accommodate the increased airflow. To address the issue that the fixed air inlet of existing box-type centrifugal fans cannot flexibly adapt to the fan's operating conditions, a new fan product is proposed to meet market demand. Summary of the Invention

[0003] The purpose of this invention is to overcome the shortcomings of the prior art and provide a box-type centrifugal fan with air intake adjustment function. This invention designs a combined air intake hood to form a main air intake chamber and an auxiliary air intake chamber. The main air intake chamber is open, and the auxiliary air intake chamber is opened and closed autonomously according to the negative pressure in the box. This invention adjusts the size of the air intake area by combining the air intake hood, thereby adapting the fan equipment to use under different operating conditions.

[0004] To achieve the above objectives, the present invention adopts the following technical solution:

[0005] A box-type centrifugal fan with air inlet adjustment function includes a box, a centrifugal impeller, and a power mechanism. The centrifugal impeller is rotatably mounted inside the box, and the power mechanism is mounted on the outside of the box and is drivenly connected to the centrifugal impeller. The outer wall of the box has an air inlet and an air outlet. The air inlet is equipped with a combined air inlet hood, which includes an outer hood and an inner hood. The outer hood is fitted onto the outside of the inner hood, forming a main air inlet chamber between the outer and inner hoods. An auxiliary air inlet chamber is formed inside the inner hood. An air inlet adjustment mechanism is installed on the outside of the inner hood to control the connection between the main air inlet chamber and the auxiliary air inlet chamber.

[0006] Furthermore, the outer cover is fixedly installed at the air inlet of the housing, the outer cover and the inner cover are installed concentrically, and the main air inlet cavity is interconnected inside and out.

[0007] Furthermore, the inner cover cylinder has a ring of equally spaced first ventilation slots on its circumferential wall. All the first ventilation slots have the same length and width. The main air inlet chamber and the auxiliary air inlet chamber are connected through the first ventilation slots. The inner side of the auxiliary air inlet chamber is open, and the outer side of the auxiliary air inlet chamber is closed by the air inlet adjustment mechanism.

[0008] Furthermore, the air intake adjustment mechanism includes a sliding cover, a control sleeve, and a transmission element. The sliding cover is movably installed on the outer end of the inner cover cylinder, thereby sealing the outer end of the auxiliary air intake cavity. The control sleeve is movably fitted on the outer side of the inner cover cylinder. The control sleeve is driven by the transmission element to move linearly along the length of the inner cover cylinder. A second ventilation groove is formed around the outer wall of the control sleeve. The number, position, and size of the second ventilation groove correspond to the first ventilation groove. The linear movement of the control sleeve causes the first and second ventilation grooves to gradually overlap.

[0009] Furthermore, the outer circumferential wall of the sliding cover is adapted to be fitted onto the outer side of the inner cover cylinder. Two inclined arc grooves are symmetrically formed on the outer circumferential wall of the sliding cover. Two symmetrically arranged pins are vertically connected to the outer wall of the inner cover cylinder. The two pins are respectively inserted into the two inclined arc grooves. The sliding cover can rotate forward or backward by sliding the pins along the inclined arc grooves.

[0010] Furthermore, a counterweight is fixedly connected to the outer circumference of the sliding cover, and the counterweight is tilted downwards as the initial installation state of the sliding cover.

[0011] Furthermore, the outer side of the inner sleeve protrudes to form two symmetrically arranged guide protrusions, and the inside of the control sleeve has two symmetrically arranged straight grooves, with the two guide protrusions respectively fitted into the two straight grooves.

[0012] Furthermore, the outer wall of the control sleeve has an annular groove, and the transmission element includes a horizontal plate and a pin. One end of the horizontal plate is fixedly connected to the outer wall of the slide cover, and the other end of the horizontal plate extends above the annular groove. The pin is upright and threadedly connected to the horizontal plate, and the end of the pin passes through the horizontal plate and is adapted to be inserted into the annular groove.

[0013] Furthermore, the outer wall of the control sleeve includes a closed section and a slotted section. The closed section covers the first ventilation slot to close the connection between the main air inlet chamber and the auxiliary air inlet chamber. The second ventilation slot is opened in the slotted section. The first ventilation slot and the second ventilation slot gradually overlap by moving the slotted section closer to the first ventilation slot.

[0014] Furthermore, a damping pad is fixedly installed at the bottom of the straight groove, and the damping pad forms frictional contact with the guide convex strip.

[0015] In summary, the present invention has the following beneficial effects:

[0016] This invention designs a combined air inlet hood to form a main air inlet chamber and an auxiliary air inlet chamber. The main air inlet chamber is open, while the auxiliary air inlet chamber is automatically controlled to open and close according to the negative pressure inside the chamber. This invention uses the combined air inlet hood to adjust the size of the air inlet area, thereby adapting to the use of the fan equipment under different operating conditions. Attached Figure Description

[0017] Figure 1 This is a front view schematic diagram of a box-type centrifugal fan with air intake adjustment function according to this embodiment;

[0018] Figure 2 This is a top view of the internal structure of a box-type centrifugal fan with air inlet adjustment function according to this embodiment;

[0019] Figure 3 This is a cross-sectional view of the combined air inlet hood in this embodiment;

[0020] Figure 4 for Figure 3 Enlarged view of point A in the image;

[0021] Figure 5 This is a front view of the sliding sleeve in this embodiment.

[0022] Figure 6 This is a side view of the sliding sleeve and control sleeve installed on the inner cover cylinder in this embodiment;

[0023] Figure 7 This is a schematic diagram of the guide connection structure between the control sleeve and the inner cover cylinder in this embodiment;

[0024] Figure 8 for Figure 7 Enlarged view at point B in the image.

[0025] Figure label:

[0026] 1. Housing, 11. Air inlet, 111. Filter device, 12. Air outlet, 2. Centrifugal impeller, 3. Power mechanism, 4. Combined air inlet hood, 41. Outer cover, 42. Inner cover, 42. First ventilation slot, 421. Column pin, 422. Guide ridge, 423. Main air inlet chamber, 43. Auxiliary air inlet chamber, 44. Air inlet adjustment mechanism, 5. Sliding cover, 51. Inclined arc groove, 511. Counterweight, 512. Control sleeve, 52. Straight groove, 521. Closed section, 522. Slotted section, 523. Second ventilation slot, 5231. Annular groove, 524. Damping pad, 525. Transmission element, 53. Horizontal plate, 531. Pin, 532. Detailed Implementation

[0027] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0028] Existing box-type centrifugal fans have the limitation of being suitable only for fixed operating conditions due to their fixed inlet size. Figure 2 As shown, the fan product has an air inlet 11, which is connected to a filter device 111. As the filter device 111 is used, its internal resistance gradually increases (due to the filter screen becoming increasingly dirty), which alters the operating environment of the fan. When the filter device 111 is brand new, its internal resistance is minimal. A fixed, large-area air inlet leads to excessively high fan intake and a rapid decrease in filter lifespan. In this case, a smaller air inlet is needed to maintain normal airflow. However, as the filter device continues to operate, its internal resistance gradually increases, causing a decrease in fan intake (normal fan intake requires overcoming both filter resistance and suction resistance; changes in intake area are inversely proportional to changes in suction resistance. If filter resistance increases while suction resistance remains constant, the intake volume decreases). The fan struggles to maintain normal intake, requiring an adjustment to enlarge the intake area to accommodate the increased airflow (enlarging the intake area reduces suction resistance, thus increasing airflow). Existing box-type centrifugal fans, due to their fixed air inlets, cannot flexibly adapt to different operating conditions.

[0029] To address the issue of existing wind turbine products not being able to flexibly adapt to different operating conditions, such as... Figures 1 to 8As shown, this embodiment discloses a box-type centrifugal fan with air inlet adjustment function, including a box body 1, a centrifugal impeller 2, and a power mechanism 3. The centrifugal impeller 2 is rotatably mounted inside the box body 1, and the power mechanism 3 is mounted on the outside of the box body 1 and is connected to the centrifugal impeller 2 for transmission. The power mechanism 3 includes components such as a motor, and the power mechanism 3 drives the centrifugal impeller 2 by means of belt and pulley transmission (the conventional driving method of box-type centrifugal fans). An air inlet 11 and an air outlet 12 are provided on the outside of the box body 1, such as... Figure 1 and Figure 2As shown, the air inlet 11 is located on the back of the housing, and the air outlet 12 is installed on the front. A volute is fitted over the outer side of the centrifugal impeller 2. After air enters through the air inlet 11, it is rectified within the housing and enters the two axial ends of the centrifugal impeller 2 (the volute has holes at the axial ends) to meet the axial air intake requirements. The air outlet 12 is correspondingly located at the tangential end of the rotation circumference of the centrifugal impeller 2 to meet the exhaust requirements of the centrifugal impeller 2. This invention designs and installs a combined air inlet hood 4 at the air inlet 11 to adjust the air intake requirements. The combined air inlet hood 4 includes an outer hood 41 and an inner hood 42. The outer hood 41 is fitted over the outer side of the inner hood 42. During product manufacturing, the outer hood 41 is (welded) fixed in place. The air inlet 11 is installed in the housing 1. The outer cover 41 and the inner cover 42 are concentrically installed and fixedly connected by stiffening plates. The outer cover 41 and the inner cover 42 form the main air inlet cavity 43, and the inner cover 42 forms the auxiliary air inlet cavity 44. The main air inlet cavity 43 is open to the inside and outside of the housing (inner refers to the inside of the housing, and outer refers to the outside of the housing) and is in a normally open state. Since the main air inlet cavity 43 has a small air inlet area, it can be used in low additional resistance operating conditions (in this scenario, the filter device 111 is initially installed and the internal resistance of the filter screen is small). The small air inlet area can reduce the air volume and ensure the operation of the fan and the filter device 111. 1. During normal operation, an air intake adjustment mechanism 5 is installed on the outer side of the inner casing 42. A first ventilation slot 421, evenly distributed around the circumference of the inner casing 42, is provided. The length and width of the first ventilation slot 421 are consistent. The main air intake chamber 43 and the auxiliary air intake chamber 44 are connected through the first ventilation slot 421. The inner side of the auxiliary air intake chamber 44 is open, allowing the air intake from the auxiliary air intake chamber 44 to merge with that from the main air intake chamber 43. The outer side of the auxiliary air intake chamber 44 is closed by the air intake adjustment mechanism 5. Thus, the air intake of the auxiliary air intake chamber 44 can only be achieved by opening the first ventilation slot 421. The opening and closing of the first ventilation slot 421 is controlled by the air intake adjustment mechanism 5. Currently, the auxiliary air inlet cavity 44 is used as a factor to increase the air inlet area. When the additional resistance of the fan product gradually increases due to the continuous use of the filter equipment 111, the air inlet adjustment mechanism 5 gradually opens the first ventilation slot 421 to allow air to enter the auxiliary air inlet cavity 44. When the main air inlet cavity 43 and the auxiliary air inlet cavity 44 enter air at the same time, the air inlet area increases significantly. The increase in air inlet area can reduce the suction resistance and significantly improve the air volume to meet the normal use requirements of the fan product. After the above design improvement, the fan product of the present invention can adjust the air inlet (area) according to different working conditions to meet the reasonable use requirements of the fan product.

[0030] like Figure 3 and Figure 6As shown, the air intake adjustment mechanism 5 includes a sliding cover 51, a control sleeve 52, and a transmission element 53. The sliding cover 51 is movably installed on the outer end of the inner cover cylinder 42, and closes the outer end of the auxiliary air intake cavity 44 (referring to the end of the auxiliary air intake cavity 44 facing the outside of the housing) through the sliding cover 51. The control sleeve 52 is movably fitted on the outer side of the inner cover cylinder 42. The sliding cover 51 and the control sleeve 52 are connected by the transmission element 53. The control sleeve 52 is driven by the transmission element 53 to move linearly along the length of the inner cover cylinder 42. A second ventilation groove 5231 is formed around the outer wall of the control sleeve 52. The number, location, and size of the second ventilation slots 5231 correspond to the first ventilation slot 421. By controlling the linear movement of the control sleeve 52, the first and second ventilation slots 421 gradually overlap. This overlap gradually opens the connection between the main air inlet chamber 43 and the auxiliary air inlet chamber 44, increasing the air intake area. The outer circumference of the sliding cover 51 is designed to fit snugly against the outer side of the inner cover cylinder 42. The sliding cover 51, as the core component for controlling the adjustment of the air intake area, adopts a design principle of autonomous driving based on the negative pressure inside the chamber. Figure 6 As shown, two inclined arc grooves 511 are symmetrically formed on the outer circumference of the sliding cover 51. Two symmetrically arranged pins 422 are vertically connected to the outer wall of the inner cover cylinder 42. The two pins 422 are respectively inserted into the two inclined arc grooves 511. The pins 422 can slide along the inclined arc grooves 511, thereby forming the rotational forward or backward movement of the sliding cover 51. The forward and backward movement of the sliding cover 51 can generate the linear movement of the control sleeve 52, thereby covering or opening the first ventilation slot 421. Figure 5 As shown, a counterweight 512 is fixedly connected to the outer circumferential wall of the sliding cover 51 of the present invention. The counterweight 512 is tilted downwards in the initial installation state of the sliding cover 51. The counterweight 512 serves to reset the sliding cover 51. The initial state of the sliding cover 51 is that it is retracted to its outermost limit, as shown. Figure 6As shown, the outer wall of the control sleeve 52 includes a closed section 522 and a slotted section 523. When the sliding cover 51 is in its initial state, the closed section 522 is located at the position of the first ventilation slot 421 of the inner cover cylinder 42. The connection between the main air inlet chamber 43 and the auxiliary air inlet chamber 44 is closed by the closed section 522 covering the first ventilation slot 421. The second ventilation slot 5231 is entirely opened in the slotted section 523. The first ventilation slot 421 and the second ventilation slot 5231 gradually overlap by the forward movement of the slotted section 523 approaching the first ventilation slot 421. The forward movement of the slotted section 523 is the forward movement of the control sleeve 52, which is caused by the rotational forward movement of the sliding cover 51. When the fan product is used in a low additional resistance operating environment, the fan... The operation is stable, with low negative pressure inside the chamber and a small pressure difference between the inside and outside of the chamber. The thrust generated by the pressure difference is insufficient to overcome the eccentric gravity of the counterweight 512. Therefore, the sliding cover 51 cannot rotate forward. The closed section 522 of the control sleeve 52 always covers the first ventilation slot 421 to close the connection between the main air inlet chamber 43 and the auxiliary air inlet chamber 44. As the fan product is used, the internal resistance generated by the continuous use of the filter equipment 111 increases, and the fan product enters a high additional resistance operating condition. The air intake of the fan product becomes difficult. At this time, the fan intake volume decreases, causing the negative pressure inside the chamber to increase rapidly. The pressure difference between the inside and outside of the chamber increases significantly. The thrust generated by the increased pressure difference can overcome the eccentric gravity of the counterweight 512, forming the sliding cover 51. The rotating forward effect also pushes the control sleeve 52 forward, causing the second ventilation slot 5231 of the slotted section 523 to gradually overlap with the first ventilation slot 421 of the inner cover cylinder 42, thereby gradually increasing the air intake area to adapt to the existing resistance operating conditions of the fan. In this invention, the counterweight 512 forms an eccentric gravity locking effect. The magnitude of the gravitational torque of the counterweight 512 determines the opening timing of the auxiliary air intake cavity 44. When the pressure difference between the inside and outside of the box cannot push the counterweight 512, it is in a low-resistance operating environment, and the fixed small area of ​​the main air intake cavity 43 can match the air intake demand. When the pressure difference between the inside and outside of the box pushes the counterweight 512, it switches to a high-resistance operating environment, requiring additional air intake area to adapt to the operating conditions. Since the second ventilation slot 5231 and the first ventilation slot 421 gradually overlap, the increase in air intake area of ​​the present invention is a smooth improvement, which is conducive to the smooth entry of airflow into the auxiliary air intake cavity 44, and achieves linear matching between air intake volume and negative pressure inside the box and changes in working environment. After the fan product is replaced with a new filter device 111, the fan product resumes the use of low additional resistance working conditions. The pressure difference between the inside and outside of the box becomes smaller, and the counterweight 512 overcomes the pressure difference thrust again to drive the sliding cover 51 to rotate and move backward. After the sliding cover 51 returns to its original position and moves backward to the outer limit, the closed section 522 of the control sleeve 52 resumes to cover the first ventilation slot 421 of the inner cover cylinder 42, so that the fan product resumes a small air intake area and meets the use of low additional resistance working conditions again.

[0031] like Figure 7 and Figure 8As shown, the outer side of the inner sleeve 42 protrudes to form two symmetrically arranged guide protrusions 423. The control sleeve 52 has two symmetrically arranged straight grooves 521 inside. The two guide protrusions 423 are respectively fitted into the two straight grooves 521. The cooperation between the guide protrusions 423 and the straight grooves 521 creates a motion guiding effect for the control sleeve 52, ensuring that the control sleeve 52 can only move linearly along the length of the inner sleeve 42. This is designed to match the corresponding overlap requirement of the second ventilation slot 5231 and the first ventilation slot 421. Figure 4 and Figure 6 As shown, the outer wall of the control sleeve 52 has an annular groove 524. The transmission element 53 includes a horizontal plate 531 and a pin 532. One end of the horizontal plate 531 is fixedly connected to the outer wall of the sliding cover 51 (welded fixed), and the other end of the horizontal plate 531 extends above the annular groove 524. The pin 532 is vertical and threadedly connected to the horizontal plate 531. The end of the pin 532 passes through the horizontal plate 531 and is adapted to be inserted into the annular groove 524. The function of the pin 532 is to drive the movement of the control sleeve 52. Since the movement mode of the sliding cover 51 is rotational forward or rotational backward, it interferes with the linear movement of the control sleeve 52. Therefore, the present invention designs a structure in which the annular groove 524 and the pin 532 cooperate. The pin 532 can slide in the annular groove 524, so as not to interfere with the rotational movement of the sliding cover 51. At the same time, the forward or backward movement of the sliding cover 51 can be transmitted to the control sleeve 52 through the pin 532 to form the linear movement effect of the control sleeve 52.

[0032] During the use of the fan product, there may be a situation where the pressure difference between the inside and outside of the housing and the counterweight 512 are in dynamic balance. In this dynamic balance state, even small changes in pressure difference can cause frequent movement and vibration of the sliding cover 51 and the control sleeve 52. This is detrimental to noise control and the stable opening of the ventilation slots. Therefore, as... Figure 8 As shown, the present invention designs a damping pad 525 (adhesive-bonded) fixedly installed at the bottom of the straight groove 521. Only the bottom of the groove is installed to avoid affecting the guiding effect. The damping pad 525 forms frictional contact with the guide protrusion 423. Under the action of frictional resistance, small pressure difference changes can be offset by frictional resistance (the frictional resistance is set at about 5N). In this way, the sliding cover 51 and the control sleeve 52 will not move frequently, stabilizing ventilation and working noise. When the pressure difference changes significantly, the frictional resistance is not enough to affect the normal movement of the sliding cover 51 and the control sleeve 52, so that the air intake area can be opened and closed normally.

[0033] The above description is merely a preferred embodiment of the present invention. The scope of protection of the present invention is not limited to the above embodiments. All technical solutions falling within the scope of the present invention's concept are within the scope of protection of the present invention. It should be noted that for those skilled in the art, any improvements and modifications made without departing from the principles of the present invention should also be considered within the scope of protection of the present invention.

Claims

1. A box-type centrifugal fan with air inlet adjustment function, characterized in that, The device includes a housing (1), a centrifugal impeller (2), and a power mechanism (3). The centrifugal impeller (2) is rotatably mounted inside the housing (1). The power mechanism (3) is mounted on the outside of the housing (1) and is connected to the centrifugal impeller (2) in a transmission. The outer wall of the housing (1) is provided with an air inlet (11) and an air outlet (12). The air inlet (11) is equipped with a combined air inlet hood (4). The combined air inlet hood (4) includes an outer hood (41) and an inner hood (42). The outer hood (41) is fitted onto the outside of the inner hood (42). A main air inlet cavity (43) is formed between the outer hood (41) and the inner hood (42). An auxiliary air inlet cavity (44) is formed inside the inner hood (42). An air inlet adjustment mechanism (5) is installed on the outside of the inner hood (42). The air inlet adjustment mechanism (5) controls the connection between the main air inlet cavity (43) and the auxiliary air inlet cavity (44).

2. A box-type centrifugal fan with air inlet adjustment function according to claim 1, characterized in that, The outer cover (41) is fixedly installed at the air inlet (11) of the box (1). The outer cover (41) and the inner cover (42) are installed concentrically. The main air inlet cavity (43) is connected inside and outside.

3. A box-type centrifugal fan with air inlet adjustment function according to claim 1, characterized in that, The inner cover cylinder (42) has a ring of equally spaced first ventilation slots (421) on its circumferential wall. All the first ventilation slots (421) have the same length and width. The main air inlet cavity (43) and the auxiliary air inlet cavity (44) are connected through the first ventilation slots (421). The inner side of the auxiliary air inlet cavity (44) is open, and the outer side of the auxiliary air inlet cavity (44) is closed by the air inlet adjustment mechanism (5).

4. A box-type centrifugal fan with air inlet adjustment function according to claim 3, characterized in that, The air intake adjustment mechanism (5) includes a sliding cover (51), a control sleeve (52), and a transmission element (53). The sliding cover (51) is movably installed on the outer end of the inner cover cylinder (42) to close the outer end of the auxiliary air intake cavity (44). The control sleeve (52) is movably fitted on the outer side of the inner cover cylinder (42). The control sleeve (52) is driven by the transmission element (53) to move linearly along the length of the inner cover cylinder (42). A second ventilation groove (5231) is circumferentially opened on the outer wall of the control sleeve (52). The number, position, and size of the second ventilation groove (5231) correspond to the first ventilation groove (421). The linear movement of the control sleeve (52) causes the first ventilation groove (421) and the second ventilation groove (5231) to gradually overlap.

5. A box-type centrifugal fan with air inlet adjustment function according to claim 4, characterized in that, The outer circumferential wall of the sliding cover (51) is adapted to be fitted to the outer side of the inner cover cylinder (42). Two inclined arc grooves (511) are symmetrically opened on the outer circumferential wall of the sliding cover (51). Two symmetrically arranged pins (422) are vertically connected on the outer wall of the inner cover cylinder (42). The two pins (422) are respectively inserted into the two inclined arc grooves (511). The sliding cover (51) rotates forward or backward by sliding along the inclined arc grooves (511).

6. A box-type centrifugal fan with air inlet adjustment function according to claim 4, characterized in that, A counterweight (512) is fixedly connected to the outer circumference of the sliding cover (51), and the counterweight (512) is tilted downwards as the initial installation state of the sliding cover (51).

7. A box-type centrifugal fan with air inlet adjustment function according to claim 4, characterized in that, The outer side of the inner sleeve (42) protrudes to form two symmetrically arranged guide protrusions (423), and the control sleeve (52) has two symmetrically arranged straight grooves (521) inside. The two guide protrusions (423) are respectively fitted into the two straight grooves (521).

8. A box-type centrifugal fan with air inlet adjustment function according to claim 4, characterized in that, The outer wall of the control sleeve (52) has an annular groove (524). The transmission element (53) includes a horizontal plate (531) and a pin (532). One end of the horizontal plate (531) is fixedly connected to the outer wall of the slide cover (51), and the other end of the horizontal plate (531) extends above the annular groove (524). The pin (532) is upright and threaded to the horizontal plate (531). The end of the pin (532) passes through the horizontal plate (531) and is adapted to be inserted into the annular groove (524).

9. A box-type centrifugal fan with air inlet adjustment function according to claim 4, characterized in that, The outer wall of the control sleeve (52) includes a closed section (522) and a slotted section (523). The closed section (522) covers the first ventilation slot (421) to close the connection between the main air inlet (43) and the auxiliary air inlet (44). The second ventilation slot (5231) is opened in the slotted section (523). The first ventilation slot (421) and the second ventilation slot (5231) gradually overlap by moving the slotted section (523) closer to the first ventilation slot (421).

10. A box-type centrifugal fan with air inlet adjustment function according to claim 7, characterized in that, A damping pad (525) is fixedly installed at the bottom of the straight groove (521), and the damping pad (525) forms a frictional contact with the guide convex strip (423).

Images