JPH0474560B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a blower that sucks in fluid centripetally from the outer circumference and discharges it from the center.

1 and 2 show an example of a conventional centripetal blower (see Japanese Patent Publication No. 55-20078). In this centripetal blower, a front stator vane 3' for giving pre-stress to incoming air, and a rotor blade 2a on the outer peripheral side of the leading edge 2a' of the rotor blade 2' which acts as a blade of the impeller 1'. Rear stator vanes 4' for converting dynamic pressure to static pressure are respectively attached to the inner peripheral side of the trailing edge 2b'.

Here, the operation of a general centripetal blower will be explained. FIG. 3 shows the blade inlet (leading edge 2) when the moving blade 2' is operated in the centripetal blower shown in FIG.
a') and the velocity triangle at the exit (trailing edge 2b') are shown. In Fig. 3, the symbol U indicates the circumferential velocity (m/s), C indicates the absolute velocity (m/s), and w indicates the relative velocity (m/s), and the subscript 1 in each symbol indicates the entrance, and 2 indicates the entrance. exit, u is the circumferential component,
m indicates a radial component.

Now, the theoretical total pressure increase P ₀ (mmAq) caused by the operation of the rotor blade 2' is given by the following equation.

P ₀ = γ/g (U ₂ Cu ₂ − U ₁ Cu ₁ ) …(1) where γ: Specific weight of fluid (Kg/m ² ) g: Acceleration of gravity (m/s ² ) Equation (1) In the case of FIG. 3, since there is no front stator vane 3', the fluid flows in approximately in the radial direction, and Cu ₁ ≈0.

Therefore, P ₀ = γ/g (U ₂ Cu ₂ )...(2) Therefore, the conventional centripetal blower has a lower U ₂ < U ₁ , and the resulting theoretical total pressure increase P ₀ becomes small. Further, the theoretical static pressure increase Ps ₀ caused by the operation of the rotor blade 2' is given by the following equation.

Ps ₀ = P ₀ −γC ₂ ² /2g (1−η) …(3) where η: differential user efficiency In equation (3), if there is no trailing stationary vane 4′, η≒
It is 0. In the case of a centrifugal fan, a vortex chamber or a vortex-shaped chamber is installed, and by improving the differential user efficiency η, the static pressure recovery of the dynamic pressure γC ₂ ² /2g is performed well, and a high static pressure can be obtained. It's getting old.

Therefore, conventionally, as shown in FIGS. 1 and 2, a circumferential component (-Cu 1 ) of the absolute velocity C in the direction opposite to the rotation direction can be applied to the outer peripheral side of the leading edge 2a' of the rotor blade ₂ '. The front stator vane 3' is installed on the inner peripheral side of the trailing edge 2b' of the rotor blade 2' to increase the theoretical total pressure rise P ₀ given by the above formula (1). is installed so that the dynamic pressure γC ₂ ² /2g in the above equation (3) can be used to recover the static pressure.

In the centripetal blower shown in FIGS. 1 and 2, when the rotor blade 2' is operated, the velocity triangle at the rotor blade leading edge 2a' and the rotor blade trailing edge 2b' is shown in FIG.

Therefore, the static pressure increase Ps obtained by this centripetal blower is given by the following equation.

Ps=γ/g(U ₂ Cu ₂ −U ₁ Cu ₁ ) −γC ₂ ² /2g(1−η)−ΔPs …(4) where ΔPs: Fan internal loss This fan internal loss ΔPs is In-wing losses,
It is expressed as the sum of the loss in the rotor blade, the loss in the rear stator blade, the right angle bending loss at the outlet, and other losses, but in a conventional centripetal blower, (a) the front stator blade 3' and the rear (b) A rotor blade with a relatively short chord length ι′ (c) By installing the trailing stator vane 4', the pulsing speed component Cu ₂
Even if the exit absolute velocity C ₂ with radial direction is made C ₃ =Cm ₃ , the inner diameter r ₃ ′ of the trailing stationary blade 4′ is smaller than the rotor blade inner diameter r ₂ ′, so C ₂ −C ₃ (d) Noise increases due to potential interference caused by the combination of rotor blades 2' and stationary blades 3' and 4', etc. (e) In general, suction Streamlines of air tend to flow perpendicularly to the leading edge of the rotor blade, so the streamlines flowing into the leading edge of the blade extending in the axial direction are aligned with the axial center in the radial direction of the impeller 1'. As a result, the inflow radius of this incoming air is equal and large over the entire leading edge 2a', so it is introduced against the large centrifugal head, and the inflow resistance becomes large. , and the suction air flowing in from the entire circumference changes its streamline direction toward the discharge port, but the opposing flows merge and collide at the axial center, causing a problem of pressure loss. , in the above equation (4), the fan internal loss ΔPs becomes large and the resulting static pressure increase Ps becomes small.

As mentioned above, conventional centripetal blowers have had the problems of low static pressure efficiency and large noise. Furthermore, there is a problem in that the structure becomes complicated due to the necessity of front stator vanes and rear stator vanes.

In view of the above-mentioned problems, the present invention provides a novel curved surface that can cause inward centripetal acceleration and outward diagonal flow acceleration in the outer peripheral surface shape of the substantially monoplane hyperboloid hub constituting the impeller. The purpose is to improve the static pressure efficiency of the blower by creating a shape that can produce centripetal acceleration in the front half of the blade and diagonal flow acceleration in the rear half. In order to achieve this purpose, an impeller having a substantially monoplane hyperboloid-shaped hub, a plurality of blades implanted therein, a guide that covers the outer periphery of the impeller, a front surface of the hub, and the guide are provided. In a blower consisting of a guide front and an inflow guide plate provided on the front side,
A front section is configured such that a suction flow path extending from the radial direction toward the front edge of the blade is formed of the inflow guide plates that are perpendicular to the axial direction and parallel to each other, and that causes centripetal acceleration diagonally inward on the outer circumferential surface of the hub. It consists of a curved surface and a rear curved surface that causes diagonal flow acceleration diagonally outward.
The blades are integrally formed continuously over the front curved surface and the rear curved surface, and the tip side of the front edge of each blade is located on the discharge side and radially outward of the hub side when viewed in the axial direction. The leading edge of each blade is inclined so that centripetal acceleration can be generated in the front half of the blade, and diagonal flow acceleration can be generated in the rear half of the blade.

Hereinafter, a blower according to an embodiment of the present invention will be described with reference to FIGS. 5 to 7.

An embodiment of the invention is shown in FIG.
This blower includes an impeller 1 having a substantially monoplane hyperboloid hub 2, a plurality of blades 3, 3, etc. implanted on the outer peripheral surface of the hub 2, a guide 4 surrounding the outer periphery of the impeller 1, and a guide 4 that covers the outer periphery of the impeller 1. In the suction region of the impeller 1, it is composed of inflow guide plates 5, 5 that are perpendicular to the axial direction and parallel to each other.

The shape of the outer peripheral surface of the hub 2 is a concave shape such that the intermediate radius r ₂ is smaller and the trailing edge radius r ₃ is larger than the leading edge radius r ₁ . That is, the diameter of the front curved surface 6a from the front edge to the middle part is gradually reduced, while the diameter of the rear curved surface 6b from the middle part to the rear edge is gradually expanded, so that r ₃ > r ₁ > r ₂ . It is formed. A main plate part 7 to which a drive shaft is to be coupled is provided approximately at the center of the inner surface of the hub 2, and can be integrally molded with synthetic resin.

Each of the blades 3 is continuously formed integrally with the front curved surface 6a and the rear curved surface 6b, and the tip side 3 of the front edge 3a of each blade 3 is
The front edge 3 of each blade ₃ is arranged so that a ₁ is located on the discharge side in the axial direction and on the outside in the radial direction than the hub side 3a 2.
a is inclined to form a large, substantially conical annular area. Reference numeral 3b indicates the trailing edge of the blade.

Furthermore, the tip side end surface 3c of each blade 3 is connected to the hub 2.
It is formed into a concave shape that is approximately the same shape as the outer peripheral surface of.

The guide 4 is formed such that its inner radius r ₄ is larger than the tip side radius r ₅ of the blade trailing edge 3b, making assembly of the impeller 1 easy.

When the impeller 1 having the above configuration is driven, the air flow W sucked in from the radial direction through the passage between the inflow guide plates 5, 5 is smoothly centripetally accelerated diagonally inward at the front half of each blade 3. The liquid is then discharged diagonally outward while being subjected to oblique flow acceleration diagonally outward in the rear half. That is, the air flow W flows from the suction side toward the discharge side while drawing a curve with a large curvature. At this time, since the leading edge 3a of each blade 3 is inclined toward the discharge side as described above,
The suction air flow can go around to the hub side portion of the leading edge 3a, and the average inflow radius of the suction air at this leading edge is small, and the inflow resistance value due to the centrifugal head can be kept much smaller than in the past. At the same time, a smooth intake air flow can be achieved, and at the same time, the flow velocity of the air that is about to flow in is lower toward the hub of the leading edge, whereas
Since the centrifugal head of a is also small, as a result, the inflow velocity is well adjusted over the entire area of this leading edge, and the leading edge 3
A substantially equal inflow velocity distribution is obtained over the entire region a, and the flow velocity inside the blade 3 is also substantially equal,
A smooth flow pattern can be realized, and unlike conventional ones, there is no problem of pressure loss due to air merging and collision at the shaft center, and pressure loss such as shape loss can be suppressed as small as possible.

FIG. 6 shows a velocity triangle at the inlet (leading edge 3a) and outlet (trailing edge 3b) of the blade in the blower shown in FIG. Static pressure rise Ps in this case
Since there is no stationary blade, it is given by the following equation.

Ps=γ/g(U ₂ Cu ₂ )−γC ₂ ² /2g−ΔPs (5) In this example, the radius rm ₁ of the average flow surface at the blade leading edge 3a and the conventional Assuming that the rotor blade outer diameter r ₁ ′ in the example is equal, the radius rm ₂ of the average flow surface at the blade trailing edge 3b is larger than the rotor blade inner diameter r ₂ ′ in the conventional example shown in FIG. Become.
This means that rm ₂ > rm ₁ and r ₂ ′ < r ₁
It is. Therefore, the exit circumferential velocity U ₂ is larger than that of the conventional example, and the circumferential component Cu ₂ of the exit edge velocity
Assuming that is the same, the theoretical total pressure increase P ₀ given by the above equation (2) is larger than that of the conventional example.

In addition, since the blade 3 of this embodiment has a relatively large chord length ι and the flow velocity in the blade passage is approximately constant, the load distribution on the blade surface is smooth, and furthermore, the air flow W is Since a streamline with a large curvature is formed along the outer peripheral surface of the fan from the diagonally inward centripetal direction to the diagonally outward diagonal flow acceleration direction, the fan internal loss ΔPs in equation (5) becomes small. On the other hand, outlet dynamic pressure γC ₂ ² /
Recovery of 2g could not be expected much in the case of the conventional example, so assuming that they are equivalent, the static pressure increase Ps in this example will be greater than that in the conventional example.

FIG. 7 shows a graph comparing the performance of the blower of this embodiment (shown by solid line) with that of the conventional example (shown by dotted line) in terms of dimensionless flow coefficient φ and static pressure coefficient ψs. According to this, the static pressure coefficient ψs in this example is approximately twice that of the conventional example.

Next, the effects of the blower of the present invention will be listed below.

(1) A front curved surface 6a that causes centripetal acceleration diagonally inward on the outer peripheral surface of the substantially monoplane hyperboloid hub 2;
Rear curved surface 6 that causes diagonal outward acceleration
b, and each blade 3 implanted on the outer peripheral surface of the hub 2 is connected to the front curved surface 6a.
and the rear curved surface 6b, and the tip side _3a1 of the front edge portion 3a of each blade 3 is located on the discharge side and radially outward from the hub side _3a2 when viewed in the axial direction. The leading edge 3a of each blade 3 is inclined so that centripetal acceleration can be generated in the front half of each blade 3, and diagonal flow acceleration can be generated in the rear half of each blade 3, so that the chord length can be increased and By making the flow velocity in the vane passage nearly constant,
Since a smooth blade surface load distribution and a streamline pattern with a large curvature can be obtained, the internal loss of the fan can be reduced, and a blower with higher performance and high static pressure efficiency can be obtained.

(2) As a result of improving the performance and static pressure efficiency of the blower, the same capacity can be produced at a lower rotation speed, and noise is reduced because there is no noise caused by potential interference caused by the presence of conventional stator blades. can be measured.

(3) The leading edge 3a of each vane 3 is arranged so that the tip side _3a1 of the leading edge 3a of each vane 3 is located on the discharge side and radially outward from the hub side _3a2 when viewed in the axial direction. By slanting the front edge 3a, the incoming airflow can go around to the right upstream part of the slanted leading edge 3a, so that a diagonal airflow is generated in a substantially orthogonal orthogonal shape to the front edge 3a, as in the conventional case. W
While flowing into the blade 3, the average inflow radius of the air flow W relative to the axis can be made smaller than in the past, and the air flow W flows into the blade 3 at a low circumferential speed, resulting in a state where the inflow resistance by the centrifugal head is small. This allows for smoother inflow. Furthermore, at the leading edge 3a of each blade 3, the flow velocity of the incoming air is balanced with the centrifugal head from the hub side 3a ₂ to the tip side 3a ₁ , so that the flow velocity of the incoming air is almost constant over the entire area of the leading edge 3a. Therefore, it is possible to effectively achieve the above-mentioned (1) substantially constant flow velocity in the vane passage.

(4) Each blade 3 planted on the outer peripheral surface of the hub 2,
It is continuously formed integrally over the front curved surface 6a and rear curved surface 6b of the hub 2, so that centripetal acceleration is generated in the front half of each blade 3, and diagonal flow acceleration is generated in the rear half of each blade 3. For example, compared to a case where the blade part that produces centripetal acceleration and the blade part that produces diagonal flow acceleration are constructed separately,
The leading edge of the downstream side (i.e., the blade part that causes diagonal flow acceleration) does not cross the turbulence of the wake of the upstream side (i.e., the blade part that causes centripetal acceleration), and aerodynamic noise can be reduced. Since the blades have a large chord length, the pressure rises smoothly on the blade surface, reducing internal pressure loss and reducing noise.

[Brief explanation of the drawing]

Figure 1 is a vertical cross-sectional view of a conventional centripetal blower;
The figure is a half-sectional view of Figure 1, Figure 3 is the velocity triangle at the blade inlet and outlet of the centripetal blower without stationary blades, and Figure 4 is the blade inlet and outlet of the centripetal blower in Figure 1. 5 is a vertical cross-sectional view of a blower according to an embodiment of the present invention, FIG. 6 is a velocity triangle of the blade inlet and outlet in the blower of FIG. 5, and FIG. 7 is a performance diagram of the blower of FIG. This is a graph comparing the conventional example (shown with a dotted line) in terms of dimensionless flow coefficient φ and static pressure coefficient ψs. 1... Impeller, 2... Hub, 3... Vane, 3a
. . . Blade leading edge, 4 . . . Guide, 6a . . . Front curved surface, 6b . . . Rear curved surface.

Claims (1)

[Claims] 1 An impeller 1 having a substantially monoplane hyperboloid hub 2 and a plurality of blades 3, 3, etc. implanted on its outer circumferential surface, and a guide guide 4 enclosing the outer circumference of the impeller 1.
and inflow guide plates 5, 5 provided on the front surface of the hub 2 and the front surface of the guide guide 4, the suction passages extending from the outside toward the front edges 3a of the blades 3 are axially perpendicular to each other. It is composed of the parallel inflow guide plates 5, 5, and the outer peripheral surface of the hub 2 is
Front curved surface 6a that causes diagonally inward centripetal acceleration
and a rear curved surface 6b that causes diagonal flow acceleration diagonally outward, and each of the blades 3 is integrally formed continuously over the front curved surface 6a and the rear curved surface 6b. Front edge 3a of blade 3
The front edge 3a of each blade 3 is inclined so that the tip side 3a ₁ is located on the discharge side in the axial direction and on the outside in the radial direction than the hub side 3a ₂ , and centripetal acceleration is achieved in the front half of each blade 3. , a blower characterized in that diagonal flow acceleration is generated in the rear half of each blade 3.