JPH02242000A - Axial blowing device for vehicle - Google Patents

Abstract

PURPOSE:To reduce noise production of an axial fan by adding an auxiliary shroud to a fan shroud to double the construction of the shroud and providing specified clearances between both shrouds and between the auxiliary shroud and the top end of each blade, to suppress blade end eddy and to weaken interference of the eddy with the rear end of a front side cylindrical section of the shroud. CONSTITUTION:Since a fan shroud 20 is doubled in its construction the confined area of the fan shroud 20 is expanded by a clearance G1 when draft resistance is low. As a result, the draft resistance of the fan shroud 20 can be reduced. Also, since the circular boundary section 26 of the inner shroud 20b is positioned ahead of the center line 31a, in fore-and-aft direction of each blade 31-31 and a clearance G2 is 3mm, interference of the circular boundary section 26 with a blade end eddy and the production of the blade end eddy can be suppressed. Thus, production of noise from a radiator fan 30 can be remarkably reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to an axial flow blower device suitable for use in a vehicle.

(Prior Art) Conventionally, in this type of vehicle axial flow blower, as shown in Japanese Utility Model Publication No. 53-6732, for example,
A cylindrical shroud extends in the direction of the engine from the outer periphery of the radiator vertically installed in front of the engine in the engine room, and a radiator fan that extends coaxially forward from the rotational axis of the engine is concentrically placed within the shroud. There is one in which an axial fan is used to draw outside air into a shroud through a radiator and guide it along the inner peripheral surface of the shroud in the direction of the engine.

(Problems to be Solved by the Invention) Generally, as vehicles become more sophisticated, there is a need to reduce the noise generated from the engine compartment. In such cases, the noise generated from the engine room will be
Noise associated with engine drive and noise generated by axial fans such as radiator fans and condenser fans for near conditioners can be broadly classified into noise generated by axial flow fans such as radiator fans and near conditioner condenser fans. In some cases, the noise from the fan is even higher. For this reason, it is essential to reduce the noise of the axial fan, but the above-mentioned configuration is still insufficient.

In response to this, the noise generated by an axial fan is based on the assumption that there is a large difference in the noise generated by the axial fan between low pressure drop when the vehicle is running at high speed and high pressure drop when the engine is idling. The only countermeasures that can be taken in reality are to adopt a complicated structure that mechanically varies the mounting elevation angle of the blades, or to match the design points of the axial flow fan to one of low pressure and high pressure, sacrificing the other design condition. Not the point.

In view of the above, the present inventors measured the state of airflow between the blades of an axial fan using a laser anemometer, and found that the pressure side and the suction side of the blade at the blade tip of the axial fan. It was discovered that the state of generation of blade tip vortices caused by the pressure difference between the blades fluctuates greatly in response to changes in ventilation resistance, and that this fluctuation has a large effect on noise generation. As a result, we realized that it is possible to reduce the noise of an axial fan by weakening the fan shroud's interference with the blade tip vortices.

Based on this understanding, the present invention aims to reduce the noise generated by the axial fan by employing a double-layered fan shroud in an axial blower.

(Means for solving the problem) In solving the problem, the structural features of the present invention are as follows:
A vehicle equipped with a fan shroud that extends from a ventilation resistor such as a radiator toward an engine located behind the fan shroud, and an axial fan that is coaxially disposed within the fan shroud and is driven by a motor. In the axial flow blower for use in the axial flow fan, a tapered front cylinder part coaxially surrounds the leading edge of each blade of the axial fan, and a front cylinder part integrally extending rearward from the front cylinder part and each of the blades. An auxiliary shroud is provided, the auxiliary shroud having a rear cylindrical portion that coaxially surrounds the tip of the fan shroud up to the rear edge of the fan shroud, and the inner periphery of the fan shroud and the outer periphery of the auxiliary shroud. A predetermined gap is provided between the auxiliary shroud and between the rear cylindrical portion of the auxiliary shroud and the tip of each blade.

(Operation and Effect) In the present invention configured as described above, the auxiliary shroud is added to the fan shroud to form a double structure,
The rear end of the front cylindrical portion of the auxiliary shroud is located on the leading edge side of each of the blades, and a predetermined gap is provided between the fan shroud and the auxiliary shroud and between the auxiliary shroud and the tip of each blade. As a result, while suppressing the blade tip vortex that is predicted to be generated on the rear tip of each blade when the axial fan is driven, the blade tip vortex and the rear end of the front cylinder part are controlled. can reduce the noise generated by the axial fan.

(Example) Hereinafter, one example of the present invention will be described with reference to the drawings.
2 and 2 show an example of an axial flow blower device for a vehicle according to the present invention.
and an engine (not shown) located behind it.

The axial blower includes a substantially cylindrical fan shroud 20 having a double structure, and a fan shroud 2 that extends from the rotating shaft of the engine.
A radiator fan 30 coaxially extends into the radiator fan 30. The fan shroud 20 has an outer shroud 20a.
is constituted by an introduction part 21 extending rearward from the back surface of the radiator 10 in a tapered shape, and a lead-out part 22 extending coaxially and cylindrically rearward from the introduction part 21. In such a case, the annular boundary portion 23 between the inlet portion 21 and the outlet portion 22 is connected to each of the blades 31 to 30 of the radiator fan 30.
It is located on the outward extension of the longitudinal center 31a of 31. The axial length of the outer shroud 20a is about 80 (mm), the axial length of the lead-out part 22 is about 15 (++m>), and the inner peripheral surface of the lead-out part 22 and the inner surface of the lead-out part 25 of the inner shroud 20b, which will be described later, are The gap G between it and the circumferential surface is set to about 5 (mm).

Further, the fan shroud 20 has an inner shroud 20b, and the inner shroud 20b is arranged between the outer shroud 20a and the radiator fan 30, and the front stays 20c to 20c and the rear stays 20a are connected to the outer shroud 20a. -206 through each screw 206-201.
and 20r to 20f are fastened concentrically. In such a case, the inner shroud 20b may
An introduction part 24 that surrounds the front edge of each wing 31 and extends rearward in a tapering shape, and a cylindrical introduction part 24 that extends coaxially rearward from this introduction part 24 and extends rearward in a cylindrical shape, surrounding the front edge of each wing 31 to 31. The lead-out portion 25 surrounds the remaining portion. Further, the annular boundary portion 26 between the introducing portion 24 and the leading portion 25 extends a predetermined length (
15 (mm)) to prevent interference with the blade tip vortices during times of high ventilation resistance. In addition, the inner shroud 20
The gap G2 between the inner circumferential surface of the lead-out portion 25 of b and the tip of each blade 31 to 31 is set to about 3 (rhymes).

In this embodiment configured in this manner, when the radiator fan 30 is driven by the engine, airflow is introduced into the fan shroud 20 through the radiator 10. Then, the outer peripheral part of the air flow introduced into the fan shroud 20 is guided along the inner peripheral surface of the introduction part 21 of the outer shroud 20a, and the inner peripheral surface of the cylindrical part 22a and the outer peripheral surface of the inner fan shroud 20b are connected. It passes through the gap and flows towards the engine. Further, the remaining part of the airflow introduced into the fan shroud 20 flows toward the engine while being guided along the inner peripheral surface of the inner shroud 20b via each blade 31 of the radiator fan 30.

In such a case, since the fan shroud 20 has a double structure as described above, the gap G1 expands the confinement area of the fan shroud 20 when the ventilation resistance is low, and as a result, the fan shroud 20 has a double structure. It is possible to reduce ventilation resistance.

Further, the annular boundary portion 26 of the inner shroud 20b is
1 to 31, and the gap G2 = 3 (am), interference with the blade tip vortex of the boundary portion 26 and suppression of the generation of the blade tip vortex. becomes possible. As a result, the generation of noise from the radiator fan 30 can be significantly reduced.

Incidentally, in the axial flow blower of this embodiment, the blade tip vortices generated in each of the blades 31 to 31 of the radiator fan 3o were measured using a laser current meter. However, low ventilation resistance (6~
7 (mAq)) hours. According to the measurement results, it was confirmed that a small blade tip vortex was generated at the rear of the tip of the blade 31, as indicated by the symbol R1 in FIG. In addition, similar measurements were performed using a coaxial flow blower with the interval G2 changed to 6 (mu). According to the measurement results, the blade tip vortices were as shown by the symbol R2 in Fig. 4. wing 31
It was confirmed that a large amount was generated at the rear of the tip.

Therefore, it can be seen that it is desirable to adopt a spacing G2 of about 3 (mm).

Further, the noise generated by the radiator fan 30 can be broadly classified into turbulence noise due to turbulence of the airflow and rotation noise due to interference between the airflow and the solid wall. Therefore, the inner shroud 20b
In FIG. 5, when the rear corner of the tip of the blade 31 is located directly below the point of intersection with the illustrated straight line P, L=O, and the position of the true 31 with respect to the inner shroud 20b is set to L as shown in FIG. =10 (mm), L=20 (mm), L
= -10 (mm), and as a result of measuring the change in the noise level at high ventilation resistance, a curve p as shown in FIG. 6 was obtained. According to this, when the distance between the annular boundary part 26 of the inner shroud 20b and the tip angle of the blade 31 is close (L=-10), the noise level is L=0 to 10.
It can be seen that this is significantly higher than in the case of

Therefore, it can be said that noise can be reduced by avoiding interference between the annular boundary portion 26 of the inner shroud 20b and the blade tip vortices. Further, it can be said that only the inner shroud 20b contributes to such noise reduction. In other words, the outer shroud 20a introduces airflow from the entire back surface of the lariat 10, increases the front opening area of the fan shroud 20 during low pressure loss, and reduces the pressure loss of the fan shroud 20 to increase the air volume during low pressure loss. The purpose is to increase and improve efficiency.

The present invention may also be applied to the case where a condenser fan of a vehicle air conditioner is used as an axial fan in combination with the radiator fan. Furthermore, the axial fan may be driven by a motor and is not limited to being driven by an engine, and the present invention may also be applied to a fan in which an axial fan drive motor is integrated into a fan shroud.

[Brief explanation of drawings]

FIG. 1 is a half-sectional view showing an embodiment of the present invention, FIG. 2 is a front view of the same, FIGS. 3 and 4 are illustrations of the generation state of blade tip vortices,
Fig. 5 is a diagram showing an example of changing the position of the radiator fan blade with respect to the inner shroud, and Fig. 6 is a graph showing the change characteristics of the noise level when the position of the radiator fan is changed as shown in Fig. 5. . Explanation of symbols 10...Radiator, 20...Fan shroud,
20a...Outer shroud, 20b...Inner shroud, 20c...Front side stay, 20d...Rear side stay, 24...Introduction section, 25. Cylindrical section, 26... Annular boundary section, 30 ...Radiator fan, 31...Tsubasa.

Claims (1)

[Claims] A vehicle equipped with a fan shroud that extends from a ventilation resistor such as a radiator toward an engine located behind the fan shroud, and an axial fan that is coaxially disposed within the fan shroud and is driven by a motor. In an axial flow blower for use in an axial flow fan, a tapered front cylinder part coaxially surrounds the leading edge of each blade of the axial fan, and a front cylinder part integrally extending rearward from the front cylinder part and each of the blades. An auxiliary shroud is provided, the auxiliary shroud having a rear cylindrical portion that coaxially surrounds the distal end rear edge of the fan shroud, the auxiliary shroud having an auxiliary shroud that is assembled to the inner periphery of the fan shroud, and that the inner periphery of the fan shroud and the outer periphery of the auxiliary shroud An axial flow blower device for a vehicle, characterized in that a predetermined gap is provided between the auxiliary shroud and the rear cylindrical portion of the auxiliary shroud and the tip of each of the blades.