HK1112044B - Axial flow blower - Google Patents

Description

Axial-flow blower

Technical Field

The present invention relates to an axial flow fan used for internal cooling of electric equipment and the like.

Background

If the electric equipment becomes small, the space in which air flows in the case of the electric equipment becomes small. Therefore, as a blower for cooling the inside of the casing, a blower having characteristics of a large air volume and a high static pressure is desired. In addition, in the blower having such characteristics, it is desirable to reduce noise as much as possible.

For example, in U.S. Pat. No. 6244818 or japanese patent application laid-open No. 2000-257597 (patent document 1), in order to meet these requirements, an axial flow fan including an impeller having nine blades and 13 stationary blades on the discharge opening side is disclosed.

Patent document 1: japanese patent laid-open No. 2000-257597 (FIGS. 1 and 4)

If a plurality of stationary blades are provided, it is confirmed that the above-mentioned requirements can be satisfied. Recently, however, depending on the application, a blower having higher performance than a conventional axial flow blower having stationary blades is sometimes required.

Disclosure of Invention

The invention aims to provide an axial flow fan which has larger air volume and higher static pressure than the prior art.

Another object of the present invention is to provide an axial flow fan capable of reducing noise compared to conventional axial flow fans.

The axial flow fan of the present invention comprises: a housing, an impeller, a motor to rotate the impeller, and a plurality of stationary blades. The housing includes an air tunnel having a suction opening portion on one side in an axial direction of the rotary shaft and a discharge opening portion on the other side in the axial direction. The impeller has a plurality of rotating blades that rotate within the wind tunnel. The plurality of rotary blades are arranged at equal intervals in the circumferential direction of the rotary shaft. The motor rotates the impeller in one rotational direction about the rotational axis. The plurality of stationary blades are disposed in the vicinity of the discharge opening in the wind tunnel. In the axial flow fan of the present invention, the number of the plurality of rotating blades is 7, and the number of the plurality of stationary blades is 8.

The inventors studied the relationship between the number of rotating blades and the number of stationary blades and the characteristics of the blower. As a result, it was found that the above-mentioned combination of the number of blades can increase the air volume of the blower and increase the static pressure as compared with the other combinations. Further, it is understood that if this combination is adopted, the generation of noise can be reduced more than in other combinations. Therefore, according to the blower of the present invention, by setting the relationship between the number of the rotary blades and the number of the stationary blades to the specific relationship, it is possible to increase the air volume of the blower and increase the static pressure, as compared with the conventional blower, and also to reduce the generation of noise.

The cross-sectional shape of the plurality of rotary blades when the rotary blades are cut in the direction orthogonal to the axial direction preferably has a curved shape in which the recess opens in one rotational direction of the impeller. In this case, the curved shape of the plurality of rotary blades is a curved shape in which the cross-sectional shape when the rotary blades are cut in the axial direction is convex in the direction opposite to the rotation direction. Further, the cross-sectional shape of the stationary blade when the stationary blade is cut in the direction orthogonal to the axial direction preferably has a curved shape in which the recess opens in the direction opposite to the rotation direction. In this case, the curved shape of the plurality of stationary blades is a curved shape having a cross-sectional shape when the stationary blades are cut in the axial direction, which is convex in the rotational direction. Specifically, if the shape of each blade is determined as described above, the maximum air volume can be increased, the maximum static pressure can be increased, and the suction noise can be reduced.

The impeller includes a rotating blade fixing member in which a plurality of rotating blades are fixed to the peripheral wall portion. The plurality of stationary blades each have an outer end fixed to an inner wall of the wind tunnel and an inner end located on a radially opposite side of the rotation axis from the outer end. A stationary blade fixing member having a peripheral wall portion with an outer diameter not larger than the outer diameter of the peripheral wall portion of the rotating blade fixing member is disposed at a central portion in the vicinity of the discharge opening in the wind tunnel. Thus, the stationary blade fixing member does not constitute a large resistance to the flow of wind generated by the rotation of the impeller. Further, the inner end portions of the plurality of stationary blades are fixed to the peripheral wall portion of the stationary blade fixing member. As a result, the stationary blade fixing member is fixed to the casing by the plurality of stationary blades. A bearing for rotatably supporting a stator and a rotating shaft of the motor is supported by the stationary blade fixing member.

Specifically, it is preferable that the plurality of stationary blades are shaped such that the length dimension of the side of the outer end of the stationary blade extending along the inner wall portion of the wind tunnel is longer than the length dimension of the side of the inner end extending along the peripheral wall portion of the stationary blade fixing member. More preferred stationary blades are shaped as follows. First, a first imaginary plane extending in the radial direction through an end of a side of an inner end of the stationary blade at a position closest to the discharge opening portion and a center line passing through the center of the rotating shaft is assumed. Then, a second imaginary plane extending in the radial direction through the end of the side of the outer end portion which the stationary blade has, which is located at the position closest to the discharge opening portion, and the center line is assumed. Further, a third imaginary plane extending in the radial direction through the center line and the end of the side of the outer end of the stationary blade located closest to the suction opening portion is assumed. The shape of the stationary blade is set so that the direction from the first virtual plane to the second virtual plane and the direction from the second virtual plane to the third virtual plane are opposite to the rotation direction of the impeller. If the shape of the stationary blade is thus determined, the shape of the stationary blade is easily set according to the required characteristics. In this case, if the angle θ 1 between the first and second hypothetical planes is set larger than the angle θ 2 between the second and third hypothetical planes, the effect of increasing the air volume can be obtained. Preferably, the angle θ 1 is in the range of 25 to 30 degrees, and the angle θ 2 is in the range of 15 to 20 degrees. With such a value, it is easy to design an axial flow fan with a large air volume and a high static pressure.

The length of the edge at the outer end of the stationary blade is preferably 40% to 50% of the length of the rotating blade extending in the axial direction. With such a value, it is easy to design an axial flow fan with a large air volume and a high static pressure.

In some cases, a plurality of lead wires are used to supply electric power to the motor without using an electric connector. In this case, the plurality of leads are led out to the outside of the housing and passed through the air tunnel. The housing is provided with a lead wire locking portion for locking the plurality of lead wires. The lead wire locking portion is provided on a wall portion surrounding the discharge opening portion of the case, and configured to lock a plurality of lead wires connected to the motor. The presence of a plurality of leads not only affects the air volume and the static pressure, but also causes noise. Therefore, in this case, it is preferable that a guide wall portion forming a guide groove for receiving the plurality of leads and guiding the leads to the lead locking portion is provided between the guide wall portion and one of the stationary blades adjacent to the lead locking portion. If such a guide wall portion is provided and a plurality of lead wires are accommodated in the guide groove, it is possible to reduce adverse effects on the air volume and static pressure and a source of noise due to the presence of the plurality of lead wires.

As described above, each of the plurality of stationary blades has an outer end fixed to the inner wall of the wind tunnel and an inner end located on the radially opposite side of the rotation axis from the outer end. Further, a stationary blade fixing member having a peripheral wall portion for fixing the inner end portions of the plurality of stationary blades is disposed at a central portion in the vicinity of the discharge opening portion in the wind tunnel. The guide wall portion includes: a first end portion located on the side of the discharge opening portion, a second end portion located on the side of the suction opening portion, a third end portion located on the side of the inner wall portion of the wind tunnel, and a fourth end portion located on the side of the stationary blade fixing member. Therefore, the first end of the guide wall portion extends from the inner wall portion of the air tunnel toward the stationary blade fixing member and is connected to the suction opening side end of the one stationary blade located on the suction opening side, so that the guide groove is formed between the guide wall portion and the one stationary blade. In this way, the presence of the guide wall portion itself can suppress the influence on the relationship between the air volume and the static pressure, and can suppress the occurrence of noise.

The third end of the guide wall is preferably fixed to the inner wall of the wind tunnel. With this configuration, the mechanical strength of the guide wall portion can be improved.

Further, the shape of the connecting portion between the first end of the guide wall portion and the suction opening side end of the one stationary blade is preferably set such that the thickness becomes thinner toward the suction opening. In this way, it is possible to suppress the coupling portion from forming a large impedance to the flow of wind generated by the rotation of the impeller.

Preferably, the second end of the guide wall is flush with the opening surface of the discharge opening. In this case, the guide wall portion preferably extends from the first end portion to the second end portion so as to be substantially orthogonal to the opening surface of the discharge opening. If the guide wall portion is provided in this manner, the resistance to the flow of wind due to the presence of the guide wall portion can be further reduced.

The lead wire locking portion may be formed of a through hole formed in the housing adjacent to an outer end of the one stationary blade and communicating an inside of the air tunnel with an outside of the housing, and a slit formed in the housing and communicating with the through hole and opening toward the other side in the axial direction. In this case, the slits are sized so that the plurality of leads accommodated in the guide grooves and extending outward from the through-holes do not easily fall out of the slits. If the lead locking portion is configured as described above, the operation of inserting the lead into the guide groove and drawing the lead out of the case is facilitated. When the lead wire locking portion is configured as described above, the third end portion of the guide wall portion is preferably fixed to the inner wall portion of the air tunnel. The length of the guide wall portion extending along the stationary blade is preferably set to a length that can prevent a part of the air flow generated by the rotation of the impeller from actively flowing out of the casing through the through hole. Thus, the wind flowing out through the through hole is almost eliminated, and the noise generation can be reduced.

Drawings

Fig. 1(a) is a perspective view of an axial flow blower according to an example of the embodiment of the present invention, as viewed from the front right obliquely upward, (B) is a perspective view of the axial flow blower as viewed from the rear left obliquely upward, and (C) is a perspective view of the axial flow blower according to the embodiment, from the front right obliquely upward, with three leads removed.

Fig. 2(a) and (B) are front and rear views of the embodiment of fig. 1 with the motor-side seal removed.

Fig. 3 is a plan view of the axial flow fan with three leads and a seal removed.

Fig. 4 is a right side view of the axial flow fan shown in fig. 2 (a).

Fig. 5 is a diagram for explaining a relationship between the rotating blades and the stationary blades.

Fig. 6 is a diagram for explaining the relationship between the rotating blades and the stationary blades.

Fig. 7 is a sectional view taken along line a-a of the motor of fig. 4, with the internal structure omitted.

Fig. 8 is a sectional view taken along line B-B of fig. 4.

Fig. 9 is a cross-sectional view taken along line C-C of the motor of fig. 4, with the internal structure omitted.

Fig. 10 is a cross-sectional view taken along line D-D of fig. 3.

Fig. 11 is a cross-sectional view taken along line E-E of fig. 3.

Fig. 12 is a sectional view taken along line F-F of fig. 3.

Fig. 13 is a sectional view taken along line G-G of fig. 3.

Fig. 14 is a graph showing the results of measuring the static pressure-air volume characteristics when the guide wall portion is provided and when the guide wall portion is not provided.

Fig. 15 is a view showing measurement results in the case where the number of rotating blades (moving blades) is fixed to 7, but the number of stationary blades (stationary blades) is changed.

Fig. 16 is a view showing measurement results in the case where the number of rotating blades (moving blades) was changed, but the number of stationary blades (stationary blades) was fixed to 8.

Detailed Description

Hereinafter, an example of an embodiment of an axial flow fan according to the present invention will be described in detail with reference to the drawings. Fig. 1(a) is a perspective view of an axial flow fan 1 according to an example of the embodiment of the present invention, as viewed from the front right obliquely upward, fig. 1(B) is a perspective view of the axial flow fan 1, as viewed from the rear left obliquely upward, and fig. 1(C) is a perspective view of the axial flow fan 1 according to the embodiment, as viewed from the front right obliquely upward, with three leads 10 removed. Fig. 2(a) and (B) are front and rear views of the embodiment of fig. 1 with the motor 9 side seal 2 removed. Fig. 3 is a plan view of the axial flow fan 1 with three leads 10 and the seal 2 removed. Fig. 4 is a right side view of the axial flow fan 1 shown in fig. 2 (a). Fig. 5 and 6 are diagrams for explaining a relationship between the rotary blade 5 and the stationary blade 11, which will be described later. Fig. 7, 8 and 9 are a sectional view taken along line a-a, a sectional view taken along line B-B, and a sectional view taken along line C-C, with the internal structure of the motor of fig. 4 omitted.

In these figures, an axial flow fan 1 has: a housing 3; an impeller 7 disposed in the casing 3 and having seven rotary blades 5; a motor 9 having a rotary shaft 8 to which the impeller 7 is attached; 8 stationary blades 11. As shown in fig. 1 and 2, the casing 3 has an annular suction-side flange 13 on one side in the axial extension direction (axial direction) of the rotary shaft 8, and an annular discharge-side flange 15 on the other side in the axial direction. The housing 3 has a cylindrical portion 17 between the flanges 13 and 15. The internal spaces of the flange 13, the flange 15, and the cylindrical portion 17 constitute an air tunnel 19.

The suction-side flange 13 has a substantially quadrangular outline shape and has a substantially circular suction opening 14 therein. The suction-side flange 13 has flat surfaces 13a at four corners, and through-holes 13b through which mounting screws pass are formed at the four corners.

The discharge-side flange 15 also has a substantially quadrangular outline shape and has a substantially circular discharge opening 16 therein. The discharge-side flange 15 has flat surfaces 15a at four corners, and through holes 15b through which mounting screws pass are formed at the four corners.

The impeller 7 includes a cup-shaped rotating blade fixing member 6, and seven rotating blades 5 are fixed to a peripheral wall portion of the rotating blade fixing member 6. A plurality of permanent magnets constituting a part of a rotor of the motor 9 are fixed to the inside of the peripheral wall portion of the rotor blade fixing member 6.

As shown in fig. 2(a) and 3, the eight stationary blades 11 include: outer ends 11A fixed to inner wall portions of the wind tunnel 19; and an inner end 11B located on the opposite side of the outer end 11A in the radial direction of the rotating shaft 8. Further, a cup-shaped stationary blade fixing member 21 having a peripheral wall portion with an outer diameter equal to or smaller than the outer diameter of the peripheral wall portion of the rotating blade fixing member 6 is disposed at the center portion in the vicinity of the discharge opening portion 16 in the wind tunnel 19, and if the dimensional relationship is set in this manner, the stationary blade fixing member 21 does not generate a large impedance to the flow of wind generated by the rotation of the impeller 7. Further, the inner end portions 11B of the eight stationary blades 11 are fixed to the peripheral wall portion of the stationary blade fixing member 21. As a result, the stationary blade fixing member 21 is fixed to the casing 3 by eight stationary blades. A bearing 23 is supported by the stationary blade fixing member 21, and rotatably supports a not-shown stator of the motor 9 and the rotating shaft 8.

Seven rotary blades 5, as shown in fig. 5, each having a cross-sectional shape when the rotary blade 5 is cut in a direction orthogonal to the axial direction of the rotary shaft 8, with a concave portion facing the rotation direction of the impeller 7 [ clockwise in fig. 2(a) ]; counterclockwise in fig. 2 (B). As shown in fig. 6, the cross-sectional shape of the seven rotary blades 5 when the rotary blades 5 are cut in the axial direction is a curved shape that is convex in the direction opposite to the rotation direction of the impeller 7. As shown in fig. 5, the cross-sectional shape of the stationary blade 11 when the stationary blade 11 is cut in a direction orthogonal to the axial direction has a curved shape in which a concave portion opens in a direction opposite to the rotational direction. As shown in fig. 6, the cross-sectional shape of the eight stationary blades 11 when the stationary blades 11 are cut in the axial direction is a curved shape that is convex in the rotational direction.

As shown in fig. 6 and 10, the eight stationary blades 11 are shaped so that a length L2 of the side of the outer end 11A of the stationary blade 11 extending along the inner wall of the air tunnel 19 is longer than a length L1 of the side of the inner end 11B of the stationary blade 11 extending along the peripheral wall of the stationary blade fixing member 21. The length L1 of the side of the inner end 11B of one stationary blade 11 adjacent to the lead locking portion 25 to be described later is shorter than the length L1 of the side of the inner end 11B of the other stationary blade 11. This is for the purpose of extracting the lead wire 10 from the motor 9 side.

A method of setting the shape of the stationary blade 11 will be described with reference to fig. 3. First, it is assumed that PS1 extending in the radial direction through the end portion 12A of the side of the inner end portion 11B of the stationary blade 11 at the position closest to the discharge opening portion 16 and the center line CL passing through the center of the rotating shaft 8. Next, an end portion 12B located at a position closest to the discharge opening portion 16 by a side of the outer end portion 11A which the stationary blade 11 has and a second imaginary plane PS2 extending in the radial direction by the center line CL are assumed. Further, a third imaginary plane PS3 extending in the radial direction through the center line CL and the end portion 12C of the outer end portion 11A of the stationary blade 11 located at the position closest to the suction opening portion 14. The shape of each stationary blade 11 is set such that the direction from the first imaginary plane PS1 to the second imaginary plane PS2 and the direction from the second imaginary plane PS2 to the third imaginary plane PS3 are opposite to the rotation direction of the impeller 7. If the shape of the stationary blade 11 is set in this manner, the shape of the stationary blade 11 can be easily set according to the required characteristics. In the present embodiment, an angle θ 1 between the first hypothetical plane PS1 and the second hypothetical plane PS2 is set larger than an angle θ 2 between the second hypothetical plane PS2 and the third hypothetical plane PS 3. Specifically, the angle θ 1 is about 30 degrees and the angle θ 2 is about 20 degrees. Preferably, the angle θ 1 is in the range of 25 to 30 degrees, and the angle θ 2 is in the range of 15 to 20 degrees. If such a size is provided, it is easy to design an axial flow fan having a large air volume and a high static pressure.

As shown in fig. 6 and 10, the length L2 of the side of the outer end 11A of the stationary blade is preferably 40% to 50% of the length L3 of the rotary blade 5 in the axial direction. If such a size is provided, it is easy to design an axial flow fan having a large air volume and a high static pressure.

The case 3 is provided with a lead locking portion 25 for locking the three leads 10. The lead wire locking portion 25 includes: a through hole 27 formed in the cylindrical portion 17 of the casing 3 adjacent to the outer end portion 11B of the adjacent one of the stationary blades 11 and allowing the interior of the air tunnel 19 to pass through the exterior of the casing 3; and a slit 29 formed in the flange 15 of the housing 3, communicating with the through hole 27, and opened toward the other side in the axial direction. In this case, the width of the slit 29 is set so that the three leads 10, which are accommodated in the guide groove 31 described later and are drawn out from the through-holes 27, do not easily fall out of the slit 29. If the lead locking portion 25 is configured as described above, the operation of inserting the lead 10 into the guide groove 31 and drawing the lead 10 out of the case 3 becomes easy. In the present embodiment, the flange 13 of the housing 3 is formed with a lead locking portion 26 for locking the lead 10 bent along the cylindrical portion 17.

In the present embodiment, as shown in fig. 1(a) and (C), 2(a), 3, 11, and 12, a guide wall portion 33 is provided, which forms a guide groove 31 that accommodates three leads 10 and guides the leads to the lead locking portion 25, between one of the stationary blades 11 adjacent to the lead locking portion 25. As shown in fig. 12 in particular, the guide wall portion 33 includes: a first end 35 located on the suction opening 14 side; a second end 37 located on the discharge opening 16 side; a third end portion 39 located on the inner wall portion side of the wind tunnel 19; and a fourth end portion 41 located on the stationary blade fixing member 21 side. The first end 35 of the guide wall portion 33 extends from the inner wall portion of the air tunnel 19 toward the stationary blade fixing member 21, and is connected to the suction opening side end 11C of the stationary blade 11 located on the suction opening 14 side to form a connection portion. As a result, the guide groove 31 is formed between the guide wall portion 33 and one stationary blade 11.

The third end portion 39 of the guide wall portion 33 is fixed to the inner wall portion of the air tunnel 19. The shape of the connection portion between the first end 35 of the guide wall 33 and the suction opening side end 11C of the one stationary blade 11 is set so that the thickness becomes thinner toward the suction opening 14 as shown in fig. 13. As a result, the connection portion can provide a large resistance to the flow of wind generated by the rotation of the impeller 7.

In the present embodiment, the second end 37 of the guide wall 32 is flush with the opening surface of the discharge opening 16. In this case, the guide wall portion 33 extends from the first end portion 35 to the second end portion 37 substantially perpendicularly to the opening surface of the discharge opening portion 16, that is, parallel to the rotation shaft 8. If such a guide wall portion 33 is provided, the resistance to the flow of wind due to the presence of the guide wall portion 33 can be made smaller. As a result, if the guide wall portion 33 is provided and a plurality of guide wires are accommodated in the guide groove, it is possible to reduce the adverse effect of the air volume and the static pressure due to the presence of the plurality of guide wires and the occurrence of noise.

In the present embodiment, the length L4 (see fig. 8 and 12) of the guide wall 33 extending along the stationary blade 11 is set to a length that can prevent a part of the air flow generated by the rotation of the impeller 7 from passing through the through hole 27 and actively flowing out of the casing 3. As a result, the wind flowing out through the through-holes 27 is substantially eliminated, and the generation of noise is reduced.

Next, in order to confirm the effect of the installation of the guide wall portion 33, the static pressure-air volume characteristics and the sound pressure level (level) were measured in the case where the guide wall portion 33 was installed or not installed. Fig. 14 shows the measurement results of the static pressure-air volume characteristics. Then, the rotation speed of the motor was set to 13000rpm which was constant, and the measurement was performed. As can be seen from fig. 14, when the guide wall portion 33 is provided to accommodate the lead wire in the guide groove 31, the air volume can be further increased and the static pressure can be increased. Further, it is known that the sound pressure level when the lead wire is accommodated in the guide groove 31 is Lp [ db (a) ], and then the sound pressure level when the guide wall portion 33 is removed is increased to Lp +3[ db (a) ]. Accordingly, it is understood that if the guide wall portion 33 is provided, noise can be reduced.

Next, a test for confirming the excellent characteristics of the axial flow blower of the present embodiment was performed by changing the number of the rotary blades 5 and the number of the stationary blades 11. Fig. 15 shows the measurement results when the number of rotating blades (rotor blades in the drawing) was fixed to 7, but the number of stationary blades (stator blades in the drawing) was changed. In fig. 15, ● indicates the results when the number of the rotary blades and the stationary blades was 7 and 8, a-solidup indicates the cases when the number of the rotary blades and the stationary blades was 7 and 7, ■ indicates the results when the number of the rotary blades and the stationary blades was 7 and 6, and x indicates the results when the number of the rotary blades and the stationary blades was 7 and 9. Fig. 16 shows measurement results obtained when the number of rotating blades (rotor blades in the drawing) was changed and the number of stationary blades (stationary blades in the drawing) was fixed to 8. In fig. 16, ● indicates the results when the number of the rotary blades and the stationary blades was 7 and 8, a-solidup indicates the cases when the number of the rotary blades and the stationary blades was 8 and 8, ■ indicates the results when the number of the rotary blades and the stationary blades was 9 and 8, and x indicates the results when the number of the rotary blades and the stationary blades was 6 and 8. As is clear from fig. 15 and 16, the air volume and the static pressure are increased when the number of the rotary blades 5 and the number of the stationary blades 11 are 7 or 8.

In addition, the results of measuring the sound pressure level are shown in table 1 below, in the case where the number of rotating blades (moving blades) is fixed and the number of stationary blades (stationary blades) is changed, and in the case where the number of rotating blades (moving blades) is changed and the number of stationary blades (stationary blades) is fixed.

Number of blades	Sound pressure level [ dB (A)]
		Moving blade 7-stationary blade 6	Lp±0
Moving blade 7-stationary blade 7	Lp+5
		Moving blade 7-stationary blade 8	Lp
Moving blade 7-stationary blade 9	Lp+0
		Moving blade 8-stationary blade 8	Lp+10
Moving blade 9-stationary blade 8	Lp+3

Note that, regarding the sound pressure level, when the sound pressure level when the lead wire is accommodated in the guide groove 31 is Lp [ db (a) ], it indicates a change in the sound pressure level when the guide wall portion 33 is removed. That is, Lp +5[ db (a) ], when the sound pressure level at the time of accommodating the lead in the guide groove 31 is Lp [ db (a) ], indicates that the sound pressure level is increased by 5[ db (a) ]. As is clear from table 1, the sound pressure level is increased in the other cases except that the sound pressure level is the same in the case where the number of the rotating blades (moving blades) and the stationary blades (stationary blades) is 7 and 8 and the case where the number of the rotating blades (moving blades) and the stationary blades (stationary blades) is 7 and 6.

As is clear from the above measurement results, when the number of the rotating blades (moving blades) is 7 and the number of the stationary blades (stationary blades) is 8 as in the axial flow fan of the present embodiment, the maximum air volume can be increased, the static pressure can be increased, and the suction noise can be reduced. It is also found from the simulation that this tendency is exhibited even when the shape of the rotating blade (moving blade) and the shape of the stationary blade (stationary blade) are changed.

Industrial applicability of the invention

According to the axial flow fan of the present invention, the number of the rotary blades and the number of the stationary blades are in a specific relationship, so that the axial flow fan has advantages of increasing the air volume of the blower and increasing the static pressure as compared with the conventional one. In addition, there is an advantage that the generation of noise can be reduced.

Claims (6)

1. An axial blower comprising:

a housing provided with an air tunnel having a suction opening portion on one side in an axial direction of a rotary shaft and a discharge opening portion on the other side in the axial direction;

an impeller including a plurality of rotating blades that rotate in the wind tunnel;

a motor that rotates the impeller in one rotational direction about the rotational axis;

a plurality of stationary blades disposed in the vicinity of the discharge opening in the wind tunnel,

and the plurality of rotary blades are arranged at equal intervals in the circumferential direction of the rotary shaft,

the plurality of stationary blades are arranged at equal intervals in a circumferential direction along the rotating shaft, and the axial-flow blower is characterized in that,

the number of the plurality of rotating blades is 7,

the number of the plurality of stationary blades is 8,

the impeller includes a rotating blade fixing member, the plurality of rotating blades are fixed to a peripheral wall portion of the rotating blade fixing member,

the plurality of stationary blades each have an outer end fixed to an inner wall of the wind tunnel and an inner end located on an opposite side of the outer end in a radial direction of the rotating shaft,

a stationary blade fixing member having a peripheral wall portion having an outer diameter dimension equal to or smaller than an outer diameter dimension of the peripheral wall portion of the rotating blade fixing member is disposed at a central portion in the wind tunnel in the vicinity of the discharge opening portion,

the inner end portions of the plurality of stationary blades are fixed to the peripheral wall portion of the stationary blade fixing member,

the plurality of stationary blades are shaped such that the length dimension of the side of the outer end portion along the inner wall portion is longer than the length dimension of the side of the inner end portion extending along the peripheral wall portion of the stationary blade fixing member,

the shape of the stationary blade is set as follows: assuming that a first imaginary plane extending in a radial direction through an end portion of the side of the inner end portion of the stationary blade located at a position closest to the discharge opening portion and a center line passing through a center of the rotation shaft, a second imaginary plane extending in a radial direction through an end portion of the side of the outer end portion of the stationary blade located at a position closest to the discharge opening portion and the center line, and a third imaginary plane extending in a radial direction through an end portion of the side of the outer end portion of the stationary blade located at a position closest to the suction opening portion and the center line, a direction from the first imaginary plane toward the second imaginary plane and a direction from the second imaginary plane toward the third imaginary plane become opposite directions of the rotation direction of the impeller, respectively,

an angle θ 1 between the first hypothetical plane and the second hypothetical plane is greater than an angle θ 2 between the second hypothetical plane and the third hypothetical plane.

2. The axial flow blower according to claim 1, wherein a cross-sectional shape of the plurality of rotary blades when the rotary blades are cut in a direction orthogonal to the axial direction has a curved shape in which a concave portion opens in the one rotation direction,

and a cross-sectional shape of the stationary blade when the stationary blade is cut in a direction orthogonal to the axial direction is a curved shape in which a concave portion opens in a direction opposite to the one rotational direction.

3. The axial flow blower according to claim 1, wherein a cross-sectional shape of the plurality of rotary blades when the rotary blades are cut in the axial direction has a curved shape that is convex in a direction opposite to the one rotation direction,

and the plurality of stationary blades have a cross-sectional shape when the stationary blades are cut in the axial direction, the cross-sectional shape having a curved shape that is convex in the one rotational direction.

4. The axial flow blower according to claim 1, wherein the angle θ 1 is 25 to 30 degrees, and the angle θ 2 is 15 to 20 degrees.

5. The axial blower of claim 1, wherein said side of said outboard end of said stationary blade has a length dimension that is 40% to 50% of a length dimension of said rotating blade extending in said axial direction.

6. The axial flow fan according to claim 1, wherein a bearing is supported by the stationary blade fixing member, and the bearing rotatably supports a stator of the motor and the rotating shaft.