JP3126263B2 - Jet fan - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an axial blower (commonly referred to as a jet fan, hereinafter referred to as a jet fan) which is installed on a ceiling portion of a road tunnel or the like, performs tunnel ventilation by the jet flow of the jet, and has the same performance in both jet directions. ).

[0002]

2. Description of the Related Art In recent years, a jet fan installed in a road tunnel or the like has been required to have high thrust and high efficiency with an increase in traffic volume in the tunnel and an increase in electricity usage fee.

Conventionally, this type of jet fan generally has a configuration as shown in FIG. Hereinafter, the configuration will be described with reference to FIG.

[0004] As shown in the figure, a cylindrical casing 101 houses an electric motor 102, and an impeller 1 is mounted on both shafts of the electric motor 102.
Nos. 03 and 103 'are directly connected to each other, and mufflers 104 are provided on both sides to absorb noise generated by the impellers 103 and 103'. The impellers 103 and 103 'are composed of blades 105 and a hub 106 having the same shape, and the blades 105 are set at an appropriate mounting angle α. The mounting angle of each of the impellers 103 and 103 'is 180.
° had been mounted differently.

In the above configuration, when the electric motor 102 rotates counterclockwise as viewed from the direction A, the pressure is increased by the main impeller 103 and further increased slightly by the auxiliary impeller 103 'to generate an airflow in the direction B. Become. The air flow at this time is shown in FIG. 5 by a velocity triangle.
In the figure, C is the absolute speed, W is the relative speed viewed from the impellers 103 and 103 ', U is the peripheral speed of the impellers 103 and 103',
ΔCu indicates the amount of increase in the turning component of the absolute speed, subscript 1 indicates the state of the entrance of the impeller 103, subscript 2 indicates the state of the exit of the impeller 103 and the state of the entrance of the impeller 103 ′, and subscript 3 indicates the state of the impeller 103 ′. Indicates the state of the exit. Conversely, the motor 102
Is rotated clockwise, the main impeller becomes 103 'and the auxiliary impeller becomes 103, and an airflow is generated in the C direction as in the counterclockwise rotation. That is, the electric motor 10
By changing the rotation direction of 2, the same performance is obtained in both directions.

[0006]

In such a conventional jet fan, for example, when the electric motor 102 rotates counterclockwise, air is boosted by the main impeller 103,
A swirl component of ΔCu ₂ is generated, and the pressure is further increased by the auxiliary impeller 103 ′, so that a swirl component of ΔCu ₃ is generated. Here, assuming that the static pressure immediately after the entrance of the jet fan is Ps ₁ and the static pressure immediately before the exit is Ps ₂ , Ps ₁ = −γ
C ₁ ² / (2g), and the order jet fan is Musei圧fan, if the discharge air flow is not have a swirling component Ps
₂ is atmospheric pressure (friction loss, disregarding the inner cylinder of the silencer). However, since conventional jet fan with swirl ^{_{component, C 2 2 = C 1 2}} + (ΔCu 2 + ΔCu 3) include ² the relationship, Ps ₂ is _{Ps 2 = -γ (ΔCu 2 +} ΔCu 3) 2 /
(2 g), which is a negative pressure with respect to the atmospheric pressure. Therefore,
Since air is blown out from the negative pressure region in the jet fan toward the atmospheric pressure, there is a problem that the thrust is low and the blower efficiency is low.

[0007] The present invention solves the above-mentioned problems. By mechanically controlling the rotation speeds of two impellers, an airflow having a small swirl component is generated, and the same performance is obtained in both blowing directions. It is a first object to provide a high thrust and high efficiency jet fan having the following characteristics.

A second object is to control the rotation speed of the two impellers to generate an airflow with a small swirling component and to provide a high thrust having the same performance in both blowing directions. It is to provide a high-efficiency jet fan.

[0009]

A first means for achieving the first object of the present invention is that a double-shaft electric motor is housed in a cylindrical casing and two impellers are blades (having an airfoil cross section). ) Are attached to both shaft ends of the two-shaft electric motor via transmissions so that the mounting angles of the two-shaft electric motors differ by 180 °, and the rotation direction of the auxiliary impeller (the impeller into which air flows in from the trailing edge of the blade) is changed to the main impeller ( An impeller into which air flows in from the leading edge of the blade)
The direction of rotation of the auxiliary impeller is set to be lower than the rotation speed of the main impeller, so that the auxiliary impeller has a function of apparently acting as a stationary blade with respect to the main impeller. The structure of a jet fan having the same performance as above.

A second means for achieving the second object is to directly connect the two impellers of the jet fan to two electric motors, and to set the number of revolutions of each electric motor by an inverter or the like. Jet fan configuration.

[0011]

According to the present invention, the configuration of the first means described above enables
By mechanically controlling the rotation speed of the impeller, the auxiliary impeller apparently acts as a stationary blade with respect to the main impeller,
It is possible to generate an airflow with a small swirling component.

In addition, by electrically controlling the rotation speed of the two impellers according to the configuration of the second means, the auxiliary impeller apparently acts as a stationary blade with respect to the main impeller, and the rotation component A small air flow can be generated.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment of the present invention will be described below with reference to FIG.

As shown in the figure, a tubular casing 1 contains a double-shaft electric motor 2 and impellers 3, 3 'are mounted on both ends of the double-shaft electric motor 2 via transmissions 7, 7', respectively. Things. In order to absorb the noise generated by the impellers 3 and 3 ', silencers 4 are provided on both sides. Impeller 3,
3 ′ is composed of a blade 5 and a hub 6 having the same shape, the blade 5 is set at an appropriate mounting angle α,
The impellers 3, 3 'are mounted such that the mounting angles differ by 180 °.

In the above configuration, when the double-shaft electric motor 2 rotates counterclockwise as viewed from the direction A, the impellers 3 and 3 'rotate to generate airflow in the direction B. At this time, the transmission 7 is set so that the rotation speed of the auxiliary impeller 3 'is lower than that of the main impeller 3 (a value determined by the blade shape, blade mounting angle, blade mounting interval, rotation speed of the impeller 3, and the like). By setting ', the auxiliary impeller 3' apparently acts as a stationary blade with respect to the main impeller 3. That is, the swirl component of the air flow can be further reduced. FIG. 2 shows the air flow at this time represented by a velocity triangle.
In the figure, C is the absolute speed, W is the relative speed viewed from the impeller 3,
W 'is the relative speed as viewed from the impeller 3', U is the peripheral speed of the impeller 3, U 'is the peripheral speed of the impeller 3', ΔCu is the amount of increase in the absolute speed turning component, and the subscript 1 is the blade The state of the entrance of the car 3, the subscript 2 indicates the state of the exit of the impeller 3 and the state of the entrance of the impeller 3 ′, and the subscript 3 indicates the state of the exit of the impeller 3 ′. At this time, the pressure of the air is increased by the main impeller 3, and a swirl component of ΔCu ₂ is generated. Then, the auxiliary impeller 3 ′ acts as a stationary blade, and the swirl component of ΔCu ₃ is converted into a static pressure. Of the static pressure Ps ₂ (negative pressure) becomes close to the atmospheric pressure.
Therefore, since air is blown from a region near the atmospheric pressure in the jet fan toward the atmospheric pressure, the thrust is higher than that of the conventional jet fan. Conversely, double shaft motor 2
Is rotated clockwise, the main impeller becomes 3 ', the auxiliary impeller becomes 3, and an airflow is generated in the C direction as in the counterclockwise rotation, and the auxiliary impeller 3 is moved relative to the main impeller 3'. Apparently it will work as a stationary wing.

As described above, according to the jet fan of the first embodiment of the present invention, the air flow with a small swirling component is generated by mechanically controlling the rotation speeds of the two impellers.
In addition, a high thrust and high efficiency jet fan having the same performance in both blowing directions can be provided.

Next, a second embodiment of the present invention will be described with reference to FIG.
This will be described with reference to FIG. As shown in the figure, the jet fan double shaft motor 2 is connected to two motors (one shaft) 8,
8 ', the impeller 3 is directly connected to the electric motor 8, and the impeller 3' is directly connected to the electric motor 8 '. The electric motor 8 is connected to an electric power source via an inverter 9; (Not shown).

In the above configuration, when the motors 8, 8 'are rotated counterclockwise as viewed from the direction A, the impellers 3, 3'
Rotate to generate an airflow in the B direction. At this time, the rotation speed of the main impeller 3 is set to an arbitrary value by the inverter 9, and the rotation speed of the auxiliary impeller 3 ′ is set to a value lower than that of the impeller 3 (blade shape, blade mounting angle, blade mounting interval, blade By setting the inverter 9 ′ so as to have a value determined by the rotation speed of the car 3 and the like, the impeller 3 ′ apparently acts as a stationary blade with respect to the impeller 3. That is, it is possible to further reduce the swirling component of the airflow for an arbitrary set wind speed. The speed triangle at this time is the same as in FIG. Conversely, when the electric motors 8 and 8 'rotate clockwise, the main impeller becomes 3' and the auxiliary impeller becomes 3, generating an airflow in the C direction. Similarly, the auxiliary impeller 3 becomes the main impeller 3 '. On the other hand, it apparently works as a stationary blade.

As described above, according to the jet fan of the second embodiment of the present invention, by controlling the rotational speeds of the two impellers electrically, an air flow with a small swirling component is generated,
In addition, a high thrust and high efficiency jet fan having the same performance in both blowing directions can be provided.

[0020]

As is apparent from the above embodiment, according to the present invention, the rotational speed of the two impellers is controlled mechanically or electrically to generate an airflow with a small swirl component. In addition, a high thrust and high efficiency jet fan having the same performance in both blowing directions can be provided.

[Brief description of the drawings]

FIG. 1 is a sectional view of a jet fan according to a first embodiment of the present invention.

FIG. 2 is a speed triangle of the jet fan of the first embodiment.

FIG. 3 is a sectional view of the jet fan of the second embodiment.

FIG. 4 is a cross-sectional view of a conventional jet fan.

Fig. 5 Same speed triangle

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Cylindrical casing 2 Double-shaft electric motor 3 Impeller 3 'Impeller 5 Blade 7 Transmission 7' Transmission 8 Electric motor 8 'Electric motor 9 Inverter 9' Inverter

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) F04D 19/02 F04D 25/16 F04D 29/32

Claims (2)

(57) [Claims] 1. A double-shaft electric motor is installed in a cylindrical casing,
Two impellers are attached to both ends of the two-shaft electric motor via transmissions so that the attachment angles of the blades (having an airfoil cross section) differ by 180 °, and an auxiliary impeller (air flows in from the trailing edge of the blade) The rotation direction of the main impeller (the impeller into which air flows in from the leading edge of the blade) and the rotation speed of the auxiliary impeller to be lower than the rotation speed of the main impeller. A jet fan in which the auxiliary impeller has the function of apparently acting as a stationary blade with respect to the main impeller, and has the same performance in both blowing directions. 2. Two impellers are directly connected to two electric motors, respectively.
2. The jet fan according to claim 1, wherein the rotation speed of each electric motor can be set electrically by an inverter or the like.