JP4033843B2 - Axial blower - Google Patents

Description

  The present invention includes a reversible electric motor and an impeller attached to the electric motor in a cylindrical casing, and the airflow in the axial length direction of the casing when the impeller is rotationally driven by the electric motor. The present invention relates to an axial blower that generates air.

Since it is used for ventilation in a tunnel, an axial blower arranged on the upper end (ceiling) of the inner wall of the tunnel is widely known (for example, see Patent Document 1). Such an axial blower described in Patent Document 1 includes a reversible electric motor and impellers provided on both sides of the electric motor in a cylindrical casing, and is provided between the electric motor and the inner wall of the casing. A plurality of plate-shaped stationary blades are provided radially, and the motor is supported inside the casing by the stationary blades. The impeller is rotationally driven by the electric motor, thereby generating an air flow in the axial length direction of the casing. In this axial blower, the airflow that has passed through the impeller upstream of the airflow becomes a swirling flow in the same direction as the rotation direction of the impeller, and proceeds to the downstream side. As a result, the flow in the axial length direction flows into the downstream impeller. Thus, the work amount of the downstream impeller can be secured without excessively increasing the rotational speed of the downstream impeller, and as a result, noise can be reduced.
Japanese Utility Model Publication No. 7-8599

  However, in the conventional axial blower as described above, although it is practically low noise and high efficiency, the noise and fan are as follows due to the stationary blade being flat. It was causing a decrease in efficiency.

  (1) Since the stationary blades were flat, strong wakes (flow unevenness) were generated on the downstream side in the process of rectifying the swirling flow from the upstream impeller into the axial flow. This wake interfered with the downstream impeller and generated noise.

  (2) The occurrence of a strong wake means that the corresponding resistance to the airflow is generated, and as a result, the fan efficiency has been reduced.

  The present invention has been made in view of such circumstances, and provides an axial blower that reduces the wake generated by a stationary blade as much as possible, has low noise as compared with the prior art, and has high fan efficiency. For the purpose.

In order to solve the above problems, an axial blower according to the present invention includes a reversible electric motor and an impeller attached to the electric motor in a cylindrical casing configured to be suspended from and supported by the upper end of the inner wall of the tunnel. when, a plurality of vanes for supporting the motor within the casing, in the axial flow fan for generating air flow in the axial direction of the casing when the impeller is rotated by said electric motor, said The plurality of stationary blades are provided radially between the electric motor and the inner surface of the casing, and the impellers are respectively provided on both sides of the motor in the axial length direction. is formed on the extended plate shape to, to be thinner toward the axial direction at both ends, is arranged to its thickness varies smoothly the axial length direction, the vanes the axial direction as the normal direction A shape of plane symmetry about a plane of symmetry passing through the axial direction center, cross-sectional shape by a plane parallel to the axial direction, forms a such a combination of two arcs of the same radius substantially convex cross shape It is characterized by being.

  By adopting such a configuration, the separation of the airflow from the surface of the stationary blade is suppressed, and thereby the wake generated on the downstream side can be made smaller than in the case of a plate-shaped stationary blade. Therefore, noise can be reduced and fan efficiency can be improved.

Further, between the inner wall of the electric motor the casing, since the plurality of vanes are configured to provided radially, it is possible to securely support the electric motor inside the casing.

Further, since the stationary blade has a configuration in which the axial direction is a normal direction and a symmetrical plane passing through the axial length center of the stationary blade has a plane-symmetric shape, At any time, the manner in which the airflow passes through the stationary blade is the same, and noise reduction and fan efficiency can be efficiently achieved both during forward rotation and during reverse rotation .

Furthermore, the shape of the stationary blade is simple because the sectional shape of the plane parallel to the axial length direction is such that two arcs of the same radius are combined into a substantially convex lens sectional shape. Therefore, the manufacture is easy, and the wake can be efficiently reduced because there is no portion having a large gradient on the surface of the stationary blade .

Furthermore, it is preferable that the impellers are respectively provided on both sides of the electric motor in the axial length direction. With this configuration, the airflow passes through the stationary blades under the same conditions during both forward and reverse rotations of the motor, and the difference in noise level and fan efficiency during forward and reverse rotations. It can be virtually eliminated .

In the said invention, it is preferable that the surface of the said stationary blade is formed smoothly.

  In the case of the axial blower according to the present invention, since there are no sharp portions at the four corners of the stationary blade as in the case where the stationary blade has a flat plate shape, the separation of the airflow from the surface of the stationary blade is suppressed. Can be made smaller than in the case of a flat plate-like stationary blade, noise can be reduced, and fan efficiency can be improved.

  Hereinafter, an axial blower according to an embodiment of the present invention will be specifically described with reference to the drawings.

(Embodiment 1)
FIG. 1 is an overall perspective view of the axial flow fan according to Embodiment 1 of the present invention, with a part cut away, and FIG. 2 shows the configuration of the axial flow fan according to Embodiment 1 of the present invention. It is side surface sectional drawing shown. As shown in FIG. 1, an axial blower 1 according to Embodiment 1 of the present invention includes a cylindrical casing 2 (corresponding to a casing according to the present invention), and a blower 3 attached inside the cylindrical casing 2. have. The cylindrical casing 2 has a cylindrical shape that extends long in one direction (axial length direction). The cylindrical casing 2 is configured as a double casing in order to provide a function as a silencer, its inner surface 4 is formed of a perforated steel plate, and a space between the inner and outer surfaces is filled with a sound absorbing material 5 (see FIG. 2). In the following description, the axial length direction is described as the left-right direction.

  The blower 3 is mainly composed of the impellers 8 and 8a, the spinners 9 and 9a, and the reversible electric motor 7, and has a bilaterally symmetric structure so as to have the same performance in both the left and right directions. That is, the air blower 3 has a symmetrical structure with respect to the symmetry plane 6 that passes through the center of the air blower 3 in the axial length direction with the axial direction as the normal direction (see FIG. 3). More specifically, a reversible electric motor 7 (not shown) having output shafts extending to both sides in the axial length direction is disposed at a central position in the cylindrical casing 2, and both output shafts of the electric motor 7 are arranged. Impellers 8 and 8a are fixed to the ends. That is, in the first embodiment, the impeller is provided in two stages on the left and right, and the airflow can be discharged in either the left or right direction depending on the rotation direction of the electric motor 7. In addition, dome-shaped spinners 9 and 9a are attached to the outer sides of the respective impellers 8 and 8a in order to smooth the airflow. Further, a plurality of stationary blades 10 are radially provided on the body of the electric motor 7 in the radial direction of the cylindrical casing 2, and their tips are fixed to the inner surface 2 of the cylindrical casing 2. As shown also in FIG. 2, the stationary blade 10 normally supports the electric motor 7 inside the cylindrical casing 2. In FIG. 1, reference numeral 11 denotes a support fitting for suspending and supporting the cylindrical casing 2 on the ceiling (inner wall upper end) of the road tunnel.

  FIG. 3 is a front cross-sectional view schematically showing the configuration of the axial blower according to Embodiment 1 of the present invention. As shown in FIG. 3, the stationary blade 10 has a substantially biconvex lens cross-sectional shape, and has a plate shape extending in the axial direction. Further, the stationary blade 10 is configured to be thinner as it goes to both ends in the axial length direction, and the thickness thereof smoothly changes in the axial length direction. More specifically, the stationary blade 10 has a cross-sectional shape formed by a plane parallel to the axial length direction such that two arcs having the same radius are combined into a substantially biconvex lens cross-sectional shape. The surface excluding both ends of the stationary blade 10 is formed smoothly without a portion where the gradient changes suddenly in order to make the air resistance as small as possible. As a result, as will be described later, the air resistance when the airflow passes through the stationary blade 10 can be reduced, and the wake generated behind the stationary blade 10 (downstream in the airflow direction) can be reduced. .

  Further, as described above, the stationary blade 10 has a substantially biconvex lens sectional shape, and therefore, the symmetry plane 6 that passes through the axial center of the stationary blade 10 with the axial direction as the normal direction. It has a symmetrical shape. Thus, since the stationary blade 10 has a bilaterally symmetric shape, the airflow passes through the stationary blade 10 in the same direction regardless of whether the airflow in the left or right direction is generated.

  In the case of the configuration of the axial blower 1 according to the first embodiment of the present invention, for example, when considering the case where the airflow flows from the left (upstream side) to the right (downstream side), the blade on the upstream side (front stage) The airflow that has passed through the vehicle 8 flows backward as a swirling flow in the same direction as the impeller 8, but the swirling flow is rectified by the stationary blade 10, and the direction of the airflow is returned to the axial length direction, downstream (rear stage). Will flow into the impeller 8a. Therefore, the load on the downstream impeller 8a is increased, and the downstream impeller 8a can perform a large amount of work accordingly. This situation is the same even if the electric motor 7 is reversed, and the same performance can be exhibited when the airflow flows in any direction. Further, by returning the airflow inflow angle to the downstream impeller 8a as viewed from the airflow direction by the stationary blade 10 supporting the reversible electric motor 7 in the axial length direction, the boosting force of the downstream impeller 8a is increased. Increase. This contributes to recovering the decrease in the boosting force when the rotational speed of the impeller 8a is reduced. As a result, the rotational speed of the impeller 8a is reduced compared to the case where the stationary blade 10 is not provided. However, a predetermined boosting force is obtained as a whole. For this reason, reduction of the noise by having reduced the rotation speed of the impeller 8a is realizable.

  Further, when the airflow sent from the impeller 8 passes through the stationary blade 10, the air travels along the surface of the stationary blade 10, but the stationary blade 10 has the shape as described above. The air resistance at this time is small, and the airflow is prevented from peeling off from the surface of the stationary blade 10. As a result, the fan efficiency of the axial blower can be improved as compared with the prior art. Moreover, the wake produced on the downstream side of the stationary blade 10 is reduced by such a decrease in air resistance. Therefore, it is possible to reduce the level of noise generated when the wake interferes with the moving blade of the downstream impeller 8a.

  In order to examine the effect of the axial flow fan according to the present invention, the inventor of the present application performs a simulation of the wake mode generated when the axial flow fan is operated, and the axial flow fan 1 according to the first embodiment and the conventional one. This was done for an axial blower. 4 is a pressure distribution diagram showing a simulation result of a wake mode in a conventional axial fan, and FIG. 5 is a pressure showing a simulation result of a wake mode in an axial fan according to Embodiment 1 of the present invention. It is a distribution map. 4 and 5 show the pressure distribution in the front view of the axial blower. As shown in FIG. 4 and FIG. 5, according to the simulation results, in both axial fans, a wake having a width that increases toward the downstream side of the airflow direction (the right side in the figure) on the downstream side of the stationary blade ( The region shown in dark gray in the figure) occurs, but it can be seen that the width of the wake in the axial blower 1 according to the first embodiment is narrower than the wake in the conventional axial blower. Thus, it turns out that the axial-flow fan which concerns on this invention is effective in reduction of a wake.

  Moreover, in order to investigate the effect by the axial-flow fan which concerns on this invention, this inventor performed the measurement experiment of the level of the noise which generate | occur | produces when operating an axial-flow fan. In this experiment, the noise level in the axial fan 1 according to the first embodiment and the noise level in the conventional axial fan were measured. FIG. 6 is a graph showing the results of such an experiment. In FIG. 6, the horizontal axis indicates the frequency (Hz), and the vertical axis indicates the noise level (dB (A)). Moreover, in FIG. 6, the experimental result of the conventional axial-flow fan with a stationary blade flat form is shown as the continuous line, and the experimental result of the axial-flow fan 1 which concerns on this Embodiment 1 is shown with the broken line. As shown in the figure, it is understood that the noise level of the axial flow fan 1 according to the first embodiment is lower than the noise level of the conventional axial flow fan at 0 to 2400 Hz. [Table 1] shows test results when the first embodiment of the present invention is applied to a forward / reverse bidirectional axial flow fan having a discharge wind force of 35 m / s and a diameter of 1250 mm. As shown in [Table 1], the overall value of the noise level (the value indicating the total sum of noise within the range of the audible frequency) is 96 dB (A) for the conventional axial flow fan, and according to the first embodiment. The axial blower 1 was 92 dB (A). Also from this, it turns out that the axial-flow fan 1 which concerns on this Embodiment 1 is low noise compared with the past.

(Embodiment 2)
FIG. 7 is a schematic front sectional view showing the configuration of the axial blower according to Embodiment 2 of the present invention. As shown in the figure, in the axial blower 101 according to the second embodiment of the present invention, the blower 103 in which only one impeller 108 is attached to the output shaft of the reversible electric motor 107 is provided inside the cylindrical casing 2. It is attached. The electric motor 107 is the same as the electric motor 7 described in the first embodiment except that the output shaft is provided only in one of the left and right directions. Further, the impeller 108 has the same configuration as the impeller 8 described in the first embodiment. About the other structure of the axial-flow fan 101 which concerns on this Embodiment 2, since it is the same as that of the structure of the axial-flow fan 1 which concerns on Embodiment 1, the same code | symbol is attached | subjected about the same component and the description is given. Omitted.

  In the axial blower 101, in both cases where the electric motor 107 rotates forward and reverse, that is, when air is sucked into the impeller 108 from the electric motor 107 side, and the impeller 108 moves toward the electric motor 107 side. In any case where air is discharged from the wake, the wake generated on the downstream side of the stationary blade 10 can be reduced. Further, when air is sucked into the impeller 108 from the electric motor 107 side, since the wake is kept small, the level of noise generated when the wake interferes with the moving blade of the downstream impeller 108 is reduced. be able to.

  In the first and second embodiments, the configuration in which the stationary blade 10 has a cross-sectional shape in which two circular arcs having the same radius are combined in a substantially biconvex lens cross-sectional shape has been described. However, the present invention is not limited to this. Instead, for example, the curvature radius of the surface of the stationary blade may be changed according to the position in the axial length direction, such as decreasing the radius of curvature of the surface of the stationary blade as approaching both ends in the axial direction.

  Furthermore, the above-described embodiment is an embodiment, and various modifications can be made without departing from the spirit of the present invention, and the present invention is not limited to the above-described embodiment.

  In the axial blower according to the present invention, the wake generated on the downstream side of the stationary blade can be reduced as compared with the case of a plate-shaped stationary blade, noise can be reduced, and fan efficiency can be improved. In a cylindrical casing, a reversible electric motor and an impeller attached to the electric motor are provided. When the impeller is rotationally driven by the electric motor, the axial direction of the casing is increased. It is useful as an axial blower or the like that generates an air current.

It is the whole perspective view which notched and showed a part of axial flow fan which concerns on Embodiment 1 of this invention. It is side surface sectional drawing which shows the structure of the axial blower which concerns on Embodiment 1 of this invention. It is front sectional drawing which shows typically the structure of the axial blower which concerns on Embodiment 1 of this invention. It is a pressure distribution figure which shows the simulation result of the aspect of the wake in the conventional axial blower. It is a pressure distribution figure which shows the simulation result of the aspect of the wake in the axial blower which concerns on Embodiment 1 of this invention. It is a graph which shows the result of the measurement experiment of the noise level of the axial flow fan which concerns on Embodiment 1 of this invention, and the conventional axial flow fan. It is typical front sectional drawing which shows the structure of the axial blower which concerns on Embodiment 2 of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Axial-flow fan 2 Cylindrical casing 3 Blower 4 Inner surface 5 Sound-absorbing material 6 Symmetric surface 7 Reversible motor 8, 8a Impeller 9, 9a Spinner 10 Stator blade 11 Support metal fitting 101 Axial fan 103 Blower 107 Reversible motor 108 Blade car

Claims (2)

In a cylindrical casing configured to be suspended and supported on the upper end of the inner wall of the tunnel , a reversible electric motor, an impeller attached to the electric motor, and a plurality of stationary blades supporting the electric motor in the casing An axial blower that generates an airflow in the axial direction of the casing when the impeller is rotationally driven by the electric motor,
The plurality of stationary blades are provided radially between the electric motor and the inner surface of the casing, and the impellers are respectively provided on both sides in the axial length direction of the electric motor.
The stationary blade is formed in a plate shape extending in the axial length direction, and is configured so that the thickness thereof smoothly changes in the axial length direction so as to become thinner toward both ends in the axial length direction. The plane is symmetrical with respect to the plane of symmetry of the stationary blade passing through the center in the axial length direction of the stationary blade, and the cross-sectional shape by a plane parallel to the axial length direction is a substantially convex lens cross section. An axial blower characterized by having a shape such as a combination . The axial-flow fan according to claim 1 , wherein the stationary blade has a smooth surface.

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