A vehicle-mounted centrifugal fan with a filtering device and a filtering method

Abstract

The application provides a vehicle-mounted centrifugal fan with a filtering device and a filtering method, which comprises a filter wheel, the filter wheel is arranged in an air inlet chamber and is installed on a fan main shaft, an impeller is installed on the fan main shaft, the filter wheel is located before an inlet of the impeller, and an outlet of the filter wheel is communicated with the inlet of the impeller. A partition plate is arranged to divide the air inlet chamber into an upper air inlet area and a lower cleaning area, a filter wheel is arranged before the inlet of the impeller in the air inlet chamber, an annular blade is arranged on the filter wheel, and a filter screen is arranged at an outer edge of the blade. When the filter wheel rotates, the annular blade is divided into three flow intervals, namely, an air suction blade, a backwashing blade and a reflux blade, by the partition plate in the circumferential direction. The air suction blade filters the water-containing and dust-containing gas from the air inlet area and guides the filtered gas into the circumferential space of the filter wheel. The backwashing blade mainly blows and washes the adhering matters on the filter screen. The reflux blade guides the gas entering the cleaning area back to the circumferential space of the filter wheel.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of vehicle-mounted centrifugal fan, in particular to a vehicle-mounted centrifugal fan with filtering device. BACKGROUND

[0002] The road and port yard cleaning sweeper is divided into three categories according to the working principle, including suction sweeping type, vacuum suction type and pure sweeping type. Among them, the suction sweeping sweeper has a disc brush and a suction disc extending out of the vehicle body. The disc brush disturbs the garbage on the ground by rotating itself and transversely throws it in front of the suction disc, which uses air power to suck it into the garbage can. The disc brush of the pure sweeping sweeper is located on both sides of the middle of the frame, which is mainly used to concentrate the garbage and convey it to the front of the rolling brush. The garbage is thrown to the conveying belt by the rolling brush in the rolling process, and then falls into the garbage can in the middle of the conveying belt. The vacuum suction sweeper has no disc brush and other cleaning mechanism, and relies on the suction disc extending out of the vehicle body to collect garbage. The suction disc suction gas power is provided by the negative pressure of the centrifugal fan. The suction nozzle width of the suction disc is the cleaning width, and it usually has better cleaning effect than the suction sweeping sweeper and the pure sweeping sweeper.

[0003] The vacuum suction sweeper adopts a deep cleaning system, which is divided into pure suction type and blowing suction type according to the different air flow movement ways. The pure suction type completely absorbs garbage through the negative pressure of the centrifugal fan inlet, and the blowing suction type realizes the cleaning operation by using negative pressure and air blowing pressure. At the same time, according to whether water is sprayed or not, it is divided into dry dust collection and wet dust collection. The dry dust collection is mainly used for the ground with large amount of dust, small particle size, difficult dust suppression and inconvenient water spraying. The wet dust collection is usually used for port and wharf yard and other occasions. The spilled material on the ground is mainly large particle size bulk material, some of which have certain viscosity. Therefore, the sweeper is required to have certain ground adherent stripping capacity and strong suction capacity. Therefore, water is usually sprayed in front of the suction port to flush and loosen the adherent on the ground, so as to realize deep cleaning.

[0004] Using wet vacuum dust collection method, a filtering device is usually arranged before the centrifugal fan inlet in the vacuum system. However, due to the limitation of vehicle space, some vehicle models are not convenient to arrange filtering device in the vacuum system. Therefore, we improve it and propose a vehicle-mounted centrifugal fan with filtering device. SUMMARY

[0005] The present application aims at the problems existing in the prior art, and in order to achieve the above-mentioned application purposes, the present application provides the following technical scheme: a vehicle-mounted centrifugal fan with a filtering device, comprising the following steps: S1, the fan air inlet chamber is designed into two space areas of an upper air inlet area and a lower cleaning area, and a filter wheel is arranged in the air inlet chamber before the impeller inlet, the filter wheel adopts a combination mode of "filtering screen + cascade", that is, an annular cascade is arranged on the filter wheel, and a filtering screen is arranged at the outer edge of the cascade, when the filter wheel rotates, the annular cascade is divided into three through-flow intervals of suction cascade, backflushing cascade and refluxing cascade in the circumferential direction by a partition plate, wherein the suction cascade is communicated with the air inlet area, the water-containing and dust-containing gas is filtered before the cascade inlet, the gas is guided into the circumferential space in the filter wheel through the cascade, the backflushing cascade and the refluxing cascade are both communicated with the cleaning area, the backflushing cascade mainly blows the adhering matters on the filtering screen, and the refluxing cascade guides the airflow entering the cleaning area back to the circumferential space in the filter wheel.

[0006] As a preferred technical scheme of the present application, S2, when the fan operates, the filter wheel rotates with the main shaft, the water-containing and dust-containing gas from the air inlet area is distributed along the outer circumferential a1-a2 of the suction cascade, the particles with large particle sizes are captured by the filtering screen arranged at the outer edge of the cascade, part of the particles is thrown outwards under the action of centrifugal force, and part of the particles adheres to the filtering screen, the filtered gas flows into the circumferential space in the filter wheel through the suction cascade (a1-a2, b1-b2); the partition plates 102 and 103 each have a certain circumferential length a2-a3, a4-a5, and respectively close the outer circumferential interval of the cascade rotating through the two positions.

[0007] As a preferred technical scheme of the present application, S3, the gas flowing into the circumferential space in the filter wheel from the outlet b1-b2 of the suction cascade, part of the gas turns into axial flow and flows to the impeller inlet, and part of the gas enters the backflushing cascade through b3-b4, and under the action of centrifugal force, the gas forms flow from the inner circumferential direction to the outer circumferential direction of the cascade.

[0008] As a preferred technical scheme of the present application, S4, the filtering screen is backflushed so as to throw off the dust and mud adhered to the filtering screen, and the gas entering the cleaning area from the outlet a3-a4 of the backflushing cascade flows into the circumferential space in the filter wheel through the refluxing cascade (a5-a1, b5-b1) after bypassing the partition plate.

[0009] As a preferred technical scheme of the present application, it comprises an air inlet chamber, a filter wheel, a main shaft, a primary impeller, a secondary impeller, a reflux elbow, a reflux device, a volute, and a front bearing, a front bearing seat, a bearing seat seal, a transparent cover, a transparent cover seal, a rear bearing, a rear bearing seat, a rear bearing seat seal, a cover, and the like, the filter wheel is installed on the main shaft and arranged in the air inlet chamber before the inlet of the primary impeller, and rotates with the main shaft during operation; the primary impeller and the secondary impeller are installed on the main shaft, and the inlet of the primary impeller is communicated with the outlet of the filter wheel.

[0010] As a preferred technical scheme of the present application, the outlet of the primary impeller is communicated with the inlet of the reflux elbow, the inlet of the secondary impeller is communicated with the outlet of the reflux device, and the secondary impeller is located in the volute.

[0011] As a preferred technical scheme of the present application, the single-stage centrifugal fan has only the primary impeller, and does not have the secondary impeller, the reflux elbow, and the reflux device, and the primary impeller is installed in the volute.

[0012] As a preferred technical scheme of the present application, the filter wheel is composed of a wheel disc, a blade row, a wheel cover, and a filter screen.

[0013] As a preferred technical scheme of the present application, the blade row is composed of a multi-wing forward blade, and the blade generatrix is a straight line parallel to the rotor axis.

[0014] As a preferred technical scheme of the present application, the outer circumferential diameter Da, the inner circumferential diameter Db, and the axial width L of the blade row are related to the air inlet flow rate of the fan, and Da and Db are the outer circumferential diameter and the inner circumferential diameter of the filter wheel, wherein Da is limited by the overall structural size of the fan, and the diameter ratio Db / Da has a proper range for controlling the passage length of the blade row.

[0015] Compared with the prior art, the present application has the following beneficial effects:

[0016] In the scheme of the present application:

[0017] 1. The air inlet chamber of the fan is designed into two spatial regions of an upper air inlet area and a lower cleaning area, and a filter wheel is arranged in the air inlet chamber before the inlet of the impeller (the primary impeller for a multi-stage fan), the filter wheel adopts a combination of a filter screen and a blade row, that is, an annular blade row is arranged on the filter wheel, and a filter screen is arranged at the outer edge of the blade row, and when the filter wheel rotates, the annular blade row is divided into three through-flow intervals of an air suction blade row, a backwash blade row, and a reflux blade row in the circumferential direction by a partition plate, wherein the air suction blade row filters the water-containing and dust-containing gas sucked in, the backwash blade row mainly blows and washes the adhering matters on the filter screen, and the reflux blade row guides the gas flow into the cleaning area back to the circumferential space of the filter wheel.

[0018] 2. When the fan is running, the filter wheel rotates with the main shaft, after the gas enters the intake area, it is distributed along the outer circumference a1-a2 of the suction cascade, the particles with larger particle size are captured by the filter screen arranged at the outer edge of the cascade, part of which is thrown outward under the action of centrifugal force, and part of which adheres to the filter screen, the filtered gas enters the suction cascade, and flows into the inner circumferential space of the filter wheel from b1-b2; the partitions 102 and 103 respectively close the outer circumferential interval of the cascade rotating through these two positions; the gas flowing into the inner circumferential space of the filter wheel from the outlet b1-b2 of the suction cascade, part of which turns into axial flow and flows to the inlet of the impeller, and part of which enters the backflushing cascade from b3-b4, forms a flow from the inner circumference to the outer circumference of the cascade under the action of centrifugal force, so as to backflush the filter screen and make the dust and mud adhered to the screen fall off; the gas entering the cleaning area from the outlet a3-a4 of the backflushing cascade, after bypassing the partition 103, flows into the inner circumferential space of the filter wheel through the return cascade (a5-a1, b5-b1), and the airflow is also filtered when passing through the filter screen at the position a5-a1. BRIEF DESCRIPTION OF DRAWINGS

[0019] Figure 1 A cross-sectional view is provided for the present application;

[0020] Figure 2 A structural schematic diagram is provided for the present application;

[0021] Figure 3 A blade angle diagram is provided for the present application;

[0022] Figure 4 A suction cascade speed triangle diagram is provided for the present application;

[0023] Figure 5 A backflushing cascade speed triangle diagram is provided for the present application;

[0024] Figure 6 A return cascade speed triangle diagram is provided for the present application;

[0025] Figure 7 A "suction-backflushing" section speed triangle diagram is provided for the present application;

[0026] Figure 8 A filter wheel structural schematic diagram is provided for the present application. DETAILED DESCRIPTION

[0027] In order to make the purpose, technical scheme and advantages of the embodiments of the present application more clear, the technical scheme in the embodiments of the present application will be described clearly and completely below in combination with the drawings. Obviously, the described embodiments are one specific embodiment of the present application, and are not limited to all embodiments.

[0028] Therefore, the following detailed description of the embodiments of the application is not intended to limit the scope of the application as claimed, but merely represents some embodiments of the application. Based on the embodiments in the application, all other embodiments obtained by those of ordinary skill in the art without creative labor fall within the scope of protection of the application.

[0029] It should be noted that the embodiments in the application and the features and technical solutions in the embodiments can be combined with each other without conflict, and it should be noted that similar reference numerals and letters represent similar items in the following drawings, and therefore, once an item is defined in one drawing, it does not need to be further defined and explained in subsequent drawings.

[0030] Embodiment 1: Please refer to Figures 1-8 A filtering method of a vehicle-mounted centrifugal fan with a filtering device, the filtering wheel 2 is installed on the fan main shaft 3, arranged in the air inlet chamber 1 before the inlet of the primary impeller 10, and rotates with the main shaft 3 during operation. The mud removing device 9 is arranged in the fan air inlet chamber 1, below the filtering wheel 2 and the bottom of the air inlet chamber 1. The primary impeller 10 and the secondary impeller 13 are installed on the main shaft 3, the inlet of the primary impeller 10 is connected with the outlet of the filtering wheel 2. For a double-stage centrifugal fan, the outlet of the primary impeller 10 is connected with the inlet of the reflux bend 11, the inlet of the secondary impeller 13 is connected with the outlet of the reflux device 12, and the secondary impeller 13 is located in the volute 18. The single-stage centrifugal fan only has the primary impeller 10, without the secondary impeller 13, the reflux bend 11 and the reflux device 12, and the primary impeller 10 is installed in the volute 18.

[0031] As an innovative structure of the application, the air inlet chamber (see Figure 2 ) is constructed with side plates 101, 105 and partition plates 102, 103, 104 and the outer circumference of the filtering wheel, thereby separating the air inlet chamber into an upper air inlet area and a lower cleaning area. Points a1, a2, …, a5 are marked on the position line of the outer circumference (Da) of the filtering wheel, and corresponding points b1, b2, …, b5 are marked on the position line of the inner circumference (Db) of the filtering wheel according to the corresponding relationship of the cascade channels.

[0032] Investigating the flow of gas in the cascade, the inlet a1-a2 of the suction cascade is connected with the upper air inlet area of the air inlet chamber, and the outlet b1-b2 is connected with the inner circumference space of the filtering wheel; the inlet b3-b4 of the backflushing cascade is connected with the inner circumference space of the filtering wheel, and the outlet a3-a4 is connected with the lower cleaning area of the air inlet chamber; the inlet a5-a1 of the reflux cascade is connected with the cleaning area, and the outlet b5-b1 is connected with the inner circumference space of the filtering wheel.

[0033] When the fan is running, the filter wheel rotates with the main shaft. After the gas enters the intake area, it is distributed along the outer periphery a1-a2 of the suction cascade. The particles with larger particle size are captured by the filter screen arranged at the outer edge of the cascade. Part of the particles are thrown outward under the action of centrifugal force, and part of the particles adhere to the filter screen. The filtered gas flows into the inner periphery space of the filter wheel through the suction cascade (a1-a2, b1-b2). The baffles 102 and 103 each have a certain circumferential length a2-a3, a4-a5, and respectively close the outer periphery interval of the cascade rotating through the two positions.

[0034] As another innovative structure of the application, the filter wheel (see Figure 8 ) is composed of a wheel disc 201, a cascade 202, a wheel cover 203, a filter screen 204, etc. The cascade is composed of multi-wing forward blades, and the blade generatrix is a straight line parallel to the rotor axis. The outer periphery diameter Da, the inner periphery diameter Db, and the axial width L of the filter wheel are related to the fan intake flow rate. Da, Db, and L are the outer periphery diameter, the inner periphery diameter, and the axial width of the cascade, respectively. Da is limited by the overall structure size of the fan. In order to control the channel length of the cascade, the diameter ratio Db / Da is large (for example, about 0.9).

[0035] After the cascade diameters Da and Db and their blade outer periphery installation angle βa and inner periphery installation angle βb are determined, the blade modeling design can be performed. The blade angles βa and βb are mainly determined according to the suction cascade inlet and outlet velocity triangle. As shown in Figure 4 , the inner and outer peripheries of the cascade are expanded into straight lines. The suction cascade, the backflush cascade, and the return cascade have the same blade angles βa and βb, but the inlet and outlet velocities and the velocity triangle are different.

[0036] Example 2: A filtering method of a vehicle-mounted centrifugal fan with a filtering device, S1, the fan intake chamber is designed into two space regions of an upper intake area and a lower cleaning area. A filter wheel is arranged in the intake chamber before the impeller (for a single-stage fan, a primary impeller) inlet. The filter wheel adopts a combination of "filter screen + cascade". An annular cascade is arranged on the filter wheel, and a filter screen is arranged at the outer edge of the cascade. When the filter wheel rotates, the annular cascade is divided into three flow intervals of a suction cascade, a backflush cascade, and a return cascade by baffles. The suction cascade filters the inhaled gas containing moisture and dust. The backflush cascade blows the adhering objects on the filter screen. The return cascade guides the gas flow in the cleaning area back to the inner periphery space of the filter wheel.

[0037] S2, when the fan is running, the filter wheel rotates with the main shaft, after the gas enters the intake area, it is distributed along the outer circumference a1-a2 of the suction cascade, the particles with larger particle size are captured by the filter screen arranged at the outer edge of the cascade, part of them are thrown outward under the centrifugal force, and part of them adhere to the filter screen, the filtered gas enters the suction cascade and flows into the inner circumferential space of the filter wheel from b1-b2; the partitions 102 and 103 each have a certain circumferential length a2-a3, a4-a5, which respectively close the outer circumferential interval of the cascade rotating through the two positions.

[0038] S3, the gas flowing into the inner circumferential space of the filter wheel from b1-b2, part of it turns into axial flow toward the inlet of the impeller, and part of it enters the backflushing cascade, under the action of centrifugal force, it forms a flow from the inner circumference b3-b4 to the outer circumference a3-a4.

[0039] S4, the gas flowing out of the backflushing cascade backflushes the filter screen at the outlet a3-a4 of the cascade, so as to make the dust and mud adhered to it fall off; the gas entering the cleaning area from a3-a4, after bypassing the partition 103, it converges into the inner circumferential space of the filter wheel through the return flow cascade (a5-a1, b5-b1).

[0040] Example 3: A vehicle-mounted centrifugal fan with a filtering device, comprising an intake chamber 1, a filter wheel 2, a main shaft 3, a primary impeller 10, a secondary impeller 13, a return bend 11, a return flow device 12, a volute 18, and a front bearing 4, a front bearing seat 5, a bearing seat seal 6, a transparent cover 7, a transparent cover seal 8, a rear bearing 14, a rear bearing seat 15, a rear bearing seat seal 16, a muff cover 17, etc. The filter wheel 2 is installed on the main shaft 3, arranged in the intake chamber 1, before the inlet of the primary impeller 10, and rotates with the main shaft 3 when running. The primary impeller 10 and the secondary impeller 13 are installed on the main shaft 3, and the inlet of the primary impeller 10 is connected with the outlet of the filter wheel 2. The outlet of the primary impeller 10 is connected with the inlet of the return bend 11, the inlet of the secondary impeller 13 is connected with the outlet of the return flow device 12, and the secondary impeller 13 is located inside the volute 18. The single-stage centrifugal fan only has the primary impeller 10, without the secondary impeller 13, the return bend 11 and the return flow device 12, and the primary impeller 10 is installed inside the volute 18. The filter wheel 2 is composed of a wheel disc 201, a cascade 202, a wheel cover 203 and a filter screen 204. The cascade 202 is composed of multiple wing-type forward blades, and the blade generatrix is a straight line parallel to the rotor axis. The outer circumferential diameter Da, the inner circumferential diameter Db and the axial width of the cascade 202 are related to the intake flow of the fan, among which Da is limited by the overall structural size of the fan. In order to control the channel length of the cascade 202, the diameter ratio Db / Da has a proper range.

[0041] Example 4: Analysis of the inlet and outlet velocity characteristics of the suction cascade, the backflushing cascade and the return flow cascade

[0042] (1) Assuming that the air flow enters the suction cascade along the radial direction, the calculation formulae of the inlet flow velocity C11, the radial flow velocity C11m and the circumferential flow velocity C11u are as follows:

[0043] C11m = Q / F1 / τ0 (m / s) (Formula 1)

[0044] In the formula, Q is the fan inlet flow, m3 / s

[0045] F1 is the suction cascade inlet (before the filter screen) flow area, F1 = 0.5*θ1*Da*L, m2

[0046] θ1 is the circumferential angle corresponding to the suction cascade, rad

[0047] τ0 is the filter screen opening rate

[0048] C11u = 0 (Formula 2)

[0049] C11 = C11m (m / s) (Formula 3)

[0050] The calculation formula of the outer circumferential linear velocity of the cascade is:

[0051] Ua = π*Da*n / 60 (m / s) (Formula 4)

[0052] In the formula, Da is the outer circumferential diameter of the cascade, m

[0053] n is the rotating speed, r / min

[0054] The calculation formula of the relative velocity at the inlet of the suction cascade is:

[0055] W11 = (Ua^2+C11^2)^0.5 (m / s) (Formula 5)

[0056] The calculation formula of the air flow angle at the inlet of the suction cascade is:

[0057] β1 = arc tan(C11 / Ua) (rad) (Formula 6)

[0058] The inlet angle i1 is set, and the blade inlet installation angle βa can be determined:

[0059] βa = β1+i1 (rad) (Formula 7)

[0060] In the formula, i1 is the inlet angle, rad

[0061] The calculation formula of the inner circumferential linear velocity of the cascade is:

[0062] Ub = π*Db*n / 60 (m / s) (Formula 8)

[0063] In the formula, Db is the inner circumferential diameter of the cascade, m

[0064] Ignoring the change of gas state parameters, the calculation formula of the radial flow velocity at the outlet of the suction cascade is:

[0065] C12m = C1m * Da / Db (m / s) (Formula 9)

[0066] The circumferential blade angle βb in the cascade is set to π / 2.

[0067] The outlet flow angle of the suction cascade is equal to the blade angle βb, and the calculation formula of the relative flow velocity W12, the absolute velocity C12, and the circumferential component C12u are as follows:

[0068] W12 = C12m (m / s) (Formula 10)

[0069] C12u = Ub (m / s) (Formula 11)

[0070] C12 = (C12m^2 + Ub^2)^0.5 (m / s) (Formula 12)

[0071] (2) The inlet and outlet flow angles of the backflow cascade are equal to the blade angles βb and βa, respectively.

[0072] After determining the inlet radial flow velocity C21m of the cascade, the calculation formula of the inlet flow velocity C21, the circumferential component C21u, and the relative flow velocity W21 are as follows:

[0073] W21 = C21m (m / s) (Formula 13)

[0074] C21u = Ub (m / s) (Formula 14)

[0075] C21 = (Ub^2 + C21m^2)^0.5 (m / s) (Formula 15)

[0076] The calculation formula of the outlet flow velocity C22, the radial flow velocity C22m, the circumferential component C22u, and the relative flow velocity W22 of the cascade are as follows:

[0077] C22m = C21m * Db / Da (m / s) (Formula 16)

[0078] W22 = C22m / sinβa (m / s) (Formula 17)

[0079] C22u = Ua + W22 * cosβa (m / s) (Formula 18)

[0080] C22 = (C22m^2 + C22u^2)^0.5 (m / s) (Formula 19)

[0081] (3) The inlet and outlet flow angles of the backflow cascade are equal to the blade angles βa and βb, respectively.

[0082] The calculation formulae of the cascade inlet flow velocity C31, radial flow velocity C31m, circumferential component C31u and relative flow velocity W31 are as follows:

[0083] C31m=C22m*θ2 / θ3 (m / s) (Formula 20)

[0084] In the formula, θ2 is the circumferential angle corresponding to the backflow cascade, rad

[0085] θ3 is the circumferential angle corresponding to the return cascade, rad

[0086] W31=C31m / sinβa (m / s) (Formula 21)

[0087] C31u=Ua+W31*cosβa (m / s) (Formula 22)

[0088] C31=(C31u^2+C31m^2)^0.5 (m / s) (Formula 23)

[0089] The calculation formulae of the cascade outlet flow velocity C32, radial flow velocity C32m, circumferential component C32u and relative flow velocity W32 are as follows:

[0090] C32m=C31m*Da / Db (m / s) (Formula 24)

[0091] W32=C32m (m / s) (Formula 25)

[0092] C32u=Ub (m / s) (Formula 26)

[0093] C32=(C32m^2+Ub^2)^0.5 (m / s) (Formula 27)

[0094] (4) In order to analyze the energy conversion relationship in the cascade, the flow of the gas along the "suction-backflow-return" route is divided into two control volumes of "suction-backflow" and "return".

[0095] The inlet and outlet velocity triangles of the "suction-backflow" section are as shown in Figure 7 It is assumed that the outlet velocity C22 of the backflow cascade and the inlet velocity C11 of the suction cascade have equal radial components, i.e. C22m=C11m, and the circumferential component of C22 is:

[0096] C22u=2Ua (m / s) (Formula 28)

[0097] Substituting Formula (2) and Formula (28) into the Euler equation P=Ua*C22u-Ua*C11u, it can be known that the Euler work obtained by the gas flowing through the "suction-backflow" cascade is:

[0098] P1=2*Ua^2 (Formula 29)

[0099] The Euler work obtained by the gas flowing through the return flow cascade is:

[0100] P2 = Ub*C32u-Ua*C31u

[0101] Substituting formula (22), formula (26) and formula (21) into the above formula, we obtain:

[0102] P2 = Ua^2*((Db / Da)^2-(1+C31m / Ua / tanβa))(formula 30)

[0103] In the formula, Db / Da<1, so P2<0, which is the expansion output work.

[0104] The total Euler work obtained by the gas flowing along the "suction-recoil-return flow" route is:

[0105] P = P1+P2, that is:

[0106] P = Ua^2*(1+(Db / Da)^2-C31m / Ua / tanβa)(formula 31)

[0107] When C31m<Ua*tanβa*(1+(Db / Da)^2), P>0. It can be seen that when the filter wheel rotates, the gas flowing through the "suction-recoil-return flow" cascade can obtain positive Euler work, and the flow is realizable.

[0108] The above examples are only used to illustrate the present application and are not intended to limit the technical solutions described in the present application. Although the present application has been described in detail with reference to the above various embodiments, the present application is not limited to the above specific embodiments, and therefore any modification or substitution of the present application; all technical solutions and improvements that do not deviate from the spirit and scope of the application are covered in the scope of the claims of the present application.

Claims

1. A filtration method for a vehicle-mounted centrifugal fan with a filtration device, characterized in that, The process includes the following steps: S1, designing the fan inlet chamber into two spatial areas: an upper inlet area and a lower cleaning area. A filter wheel is installed inside the inlet chamber, before the impeller inlet. The filter wheel uses a combination of a filter screen and blades. An annular blade is installed on the filter wheel, and a filter screen is installed at the outer edge of the blade. When the filter wheel rotates, the annular blade is divided circumferentially by a partition, resulting in three flow sections: an intake section, a backflush section, and a return flow section. The intake section is connected to the inlet area and filters the water- and dust-laden gas from the inlet area, guiding the filtered gas into the circumferential space inside the filter wheel. Both the backflush section and the return flow section are connected to the cleaning area. The backflush section mainly washes away the adhering substances on the filter screen, while the return flow section guides the airflow entering the cleaning area back into the circumferential space inside the filter wheel. S2, When the fan is running, the filter wheel rotates with the main shaft. The gas from the intake zone is distributed along the outer circumference a1 to a2 of the intake section. Larger particles are captured by the filter screen set at the outer edge of the blade grid. Some of them are thrown outward under the action of centrifugal force, and some are adhered to the filter screen. The filtered gas flows from the outer circumference a1 to a2 of the intake section to the inner circumference b1 to b2 of the intake section and enters the inner circumferential space of the filter wheel. The partition includes partition one (102) and partition two (103). Partition one (102) and partition two (103) each have a certain circumferential length. Partition one (102) closes the outer circumferential interval a2 to a3 that rotates through the lower left side of the filter wheel, and partition two (103) closes the outer circumferential interval a4 to a5 that rotates through the lower right side of the filter wheel. S3, the gas flowing into the inner circumferential space of the filter wheel from the intake section, part of which turns into axial flow and flows towards the impeller inlet, and part of which enters the backwash section. Under the action of centrifugal force, it forms a flow from the inner circumference b3-b4 of the backwash section to the outer circumference a3-a4 of the backwash section. S4, the gas flowing out of the backwash section backwashes the filter screen, causing the dust and mud adhering to it to be thrown off; the gas entering the cleaning zone from the outer circumference a3 to a4 of the backwash section, after bypassing the second partition (103), flows through the outer circumference a5 to a1 of the return flow section to the inner circumference b5 to b1 of the return flow section, and enters the inner circumferential space of the filter wheel.

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