JPH0311114A - Fan device installed onto heat exchanger - Google Patents

Abstract

PURPOSE:To reduce the noise due to the disturbance of air stream by setting the blade top edge of a cooling fan in inclination for the axis direction and setting a fan shroud oppositely to the blade top edge through a nearly uniform tip clearance. CONSTITUTION:As for the radiator 2 of an engine 1, the blade top edge of a cooling fan 8 is not parallel to a shaft 7 and on one supposed conical surface and has a tilt angle (alpha) for the direction of the shaft 7. Further, also a fan shroud 4 is set oppositely to the blade top edge through a nearly uniform tip clearance (t) on the outer peripheral part 9 of the fan 8. Therefore, the angle theta' which is formed between the outer peripheral part 9 of the fan 8 and the connection part 5 of the fan shroud 4 through the contraction of the outer peripheries of the radiator 2 and the fan 8 reduces by the tilt angle (alpha). Since the angle formed by the above-described both is small, because of the inclination of the fan shroud 4 in two states, the generation of noise due to the disturbance of air stream can be reduced.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a heat exchanger attached to a heat exchanger, such as those used in automobile engines, air conditioners, etc., for heat exchange of heating or cooling gas. This invention relates to a fan device that circulates water to a container.

[Conventional technology]

FIG. 5 shows a cooling fan device for an automobile engine as an example of the prior art. (For details, see, for example, Japanese Utility Model Publication No. 50-38684.) Cooling water from the engine 1 is led to a radiator 2, which is a heat exchanger, by a hose (not shown), and a cooling fan 3 driven by the engine is connected to the radiator. By sucking outside air through the radiator 2 or by adding ram pressure from the vehicle's running wind, the cooling air flow passing through the radiator absorbs heat from the cooling water flowing through the radiator, and the cooling water itself is heated and discharged to the rear.

In order to increase the efficiency of the cooling fan, the back of the radiator 2 is covered and the diameter is clearly reduced toward the outer part of the cooling fan 3.
A fan shroud 4 that guides cooling airflow to a cooling fan 3
will be provided. The connection part 5 of the fan shroud is reduced in diameter.
and an outer enclosure portion 6 surrounding the fan 3. Gap t between the blade tip edge of the cooling fan 3 and the inner surface of the fan shroud 4
It is generally said that the smaller the tip clearance (referred to as tip clearance), the better, but in order to avoid contact between the two due to engine vibrations, etc., there is a limit to how small the clearance can be. If it is supported on the side, it usually needs to be about 6 inches or more for safety reasons.

[Problem to be solved by the invention]

In the conventional cooling fan device shown in FIG. 5, it is desirable to make the tip clearance t as small as possible in order to increase the fan efficiency and increase the air volume, as well as to reduce fan noise. Ta. It was believed that if the tip clearance was large, the influence of the tip vortex would be greater and the vortex would become larger, which would not only reduce the efficiency of the fan, but also cause the turbulence caused by the vortex to generate noise.

However, as a result of experiments and measurements conducted by the inventors on fans and fan shrouds of various shapes and sizes using a laser current meter, etc., we found that the smaller the tip clearance t, the smaller the better. From the perspective of noise generation, we discovered that there is a tip clearance value at which the noise level is minimal. The tip clearance does not need to be extremely narrow, and the cause of noise in the conventional cooling fan device as shown in FIG. This is the result of flow turbulence caused by the airflows colliding near the true tip of the fan 3, and that the above-mentioned flow collision occurs by reducing the inclination angle θ of the connection part of the fan shroud. It has been found that if the noise is avoided, the noise is significantly reduced due to less turbulence.

However, it is generally not allowed to lengthen the fan shroud 4 by increasing the distance between the radiator 2 and the engine 1, and due to the geometrical constraints that the radiator 2 is rectangular and the cooling fan 3 is circular, the cooling fan The actual situation is that the above problem cannot be solved even if the angle of inclination θ is increased, so it is not easy to reduce the inclination angle θ. Therefore, it is an object of the present invention to deal with the new mechanism of noise generation that has been investigated in this way and to provide a solution that can actually be adopted.

[Means to solve the problem]

In order to solve the above-mentioned problems, the present invention includes a fan for gas circulation placed opposite to a heat exchanger, and a fan that guides gas flow by covering them from the back of the heat exchanger to the outer periphery of the fan. a shroud, the fan is inclined with respect to the fan axis such that the tip edges of the fan lie on an imaginary conical surface expanding toward the heat exchanger; and the fan shroud includes: The fan shroud has an inclined connecting portion connecting the heat exchanger and the fan outer surrounding portion, and the fan outer surrounding portion of the fan shroud is inclined at substantially the same angle in accordance with the inclination of the blade tip edge of the fan. a conical inner surface connected to the connecting portion, and the fan and the fan shroud are capable of changing their relative axial positions with respect to each other, thereby adjusting the size of the gap therebetween. To provide a fan device attached to a heat exchanger, characterized in that:

[For production]

Since the fan device according to the present invention has the configuration as described above, the gas flow that has passed through the heat exchanger and has been heated or cooled is reduced in diameter by the connecting portion of the fan shroud and is drawn into the circular fan surrounding portion. Ru. At this time, the gas flow flowing from the heat exchanger into the fan along the connection part of the fan shroud and the gas flow flowing into the fan almost axially along the fan enclosure join near the outer end of the fan blade. However, since both the connecting part and the surrounding part have sloped surfaces that widen toward the heat exchanger, and the angle between them is relatively small, there is relatively little turbulence in the flow, which reduces noise. Outbreak remains at low levels.

The gap between the fan blade tip edge and the fan shroud envelope (tip clearance) can be finely adjusted by moving the fan or fan shroud axially relative to its counterpart, thus minimizing noise levels. It is possible to adjust the noise to the optimum value, thereby further reducing noise.

〔Example〕

FIG. 1 shows, as a first embodiment of the present invention, a cooling fan device in which a cooling fan shaft 7 is supported coaxially with a cooling water pump (not shown) on the engine 1 side and is directly driven by the engine 1. . The cooling fan shaft 7 is provided with a fan pulley, etc. for receiving power, but the engine 1, the radiator 2, and the cooling fan shaft 7 are connected to a fifth motor, which is not shown in FIG.
The cooling fan 8 may be similar to the conventional example shown in the figure, but the blade tip edge of the cooling fan 8 is not parallel to the axis 7, but is on one virtual conical surface, and has an inclination angle with respect to the direction of the axis 7. It has α. The fan shroud 4 also faces the tip of the fan blade through a tip clearance t that is approximately - in the outer surrounding area of the fan 8, so the fan shroud 4
The outer wall of the fan is also conical, and its inclination angle is also α.

Therefore, the connecting portion 5 where the fan shroud 4 connects the radiator 2 and the outer periphery of the cooling fan 3 by reducing the diameter thereof is connected to the fan 3.
The angle θ' formed by the outer circumferential portion of Compared to , it is smaller by θ−θ′=α.

Furthermore, in the first embodiment, in order to finely adjust the tip clearance L, an adjusting device as shown in an enlarged view in FIG. 2 is provided in the attachment of the fan shroud 4 to the heat sink 2. Reference numeral 10 denotes a frame member attached around the radiator 2, in which slits 11 are cut in the axial direction at multiple locations, and several slits 12 perpendicular to the slits 11 are provided as necessary. . fan shroud 4
Screws 13 that enter the slits 11 and 12 are screwed into the slits 11 and 12, and by screwing the screws 13 at appropriate positions in the slits 11, the axial position of the fan shroud 4 is determined, and the fan shroud 4 will be supported by the heat sink 2.

Figure 4 shows experimental results showing the relationship between tip clearance L and noise level. As mentioned above, we have discovered through experiments that the smaller the tip clearance t is, the better it is to reduce the noise level, but that there is a value at which the noise level takes a minimum value. , and it was found that if the tip clearance was made smaller than that value, noise would increase, contrary to common sense. The example shown in Figure 4 shows that the best tip clearance is 3 to 4II11, which means that in a conventional engine-directly connected cooling fan device (such as the one shown in Figure 1), the tip clearance is the best. Contrary to the fact that the tip clearance is set at 61 or more for safety reasons, the clearance must be made smaller than with conventional technology.
The risk of contact appears to be greater.

However, this is because the blade tip of the fan 8 and the part of the fan shroud 4 surrounding it are both inclined by an angle α, and the tip clearance t is adjusted by adjusting the fan shroud 4 by the fine adjustment device shown in FIG. Since the fan 8 can be moved in the axial direction and adjusted to the optimum value without variation, the fan 8 is supported on the side of the engine 1 as shown in FIG. Even when large relative vibrations occur, there is no risk of contact occurring between the fan 8 and the shroud 4.6 In the first embodiment shown in FIG. In addition, since the fan surrounding portion of the fan shroud 4 is conical, the transition point from the connecting portion 5 to the fan surrounding portion is reduced by the angle of inclination α. Since the inclination angle θ' is smaller than the angle θ in FIG. 5, the turbulence caused by the collision between the flow along the surface of the shroud 4 and the flow in the axial direction at the tip of the blade of the fan 3 is reduced. The noise level is significantly reduced.

Next, FIG. 3 shows a second embodiment in which the present invention is applied to an electric cooling fan device. Cooling fan 8′ in this example
is driven by an electric motor 14, which is supported by the radiator 2 via a plurality of arms 15 and the fan shroud 4.

The inclination of the blade tip edge of the fan 8' and the inclination of the fan envelope 9' of the fan shroud 4, which are one feature of the present invention, are the same as in the first embodiment (FIG. 1) described above. Therefore, the explanation is omitted here. The tip clearance t adjusting device in the second embodiment includes an annular frame 16 supported by a plurality of arms 15 attached to the end of the shroud 4, and a slit 17 provided in the axial direction with respect to the annular frame 16.
and a screw 18 screwed onto the electric motor 14. The cooling fan 8' is moved in the axial direction together with the electric motor 14 to adjust the tip clearance t to an optimum value, and the screw 18 is tightened to fix the position.

In the case of the second embodiment, since the relative vibration between the fan 8' and the shroud 4 is small, the optimal value of the tip clearance (
Even if the value that causes the minimum value in FIG. 4 is a very small value, it is easy to adjust to it.

Furthermore, the present invention is not limited to a cooling fan device for a radiator;
Generally, it can be applied to a fan device installed in a heat exchanger.

[Effects of the Invention] According to the present invention, the tip clearance can be finely adjusted very easily, so that the noise level can be adjusted to an optimum value showing a minimum value, thereby reducing noise. Also,
Since the fan shroud has two levels of inclination and the angle between the two is small, noise generation due to airflow turbulence is also reduced, making it possible to significantly reduce noise as a whole.

Moreover, this measure does not reduce the efficiency of the fan; on the contrary, the efficiency can be improved by reducing turbulence.

[Brief explanation of the drawing]

Fig. 1 is a cross-sectional view showing one embodiment of the fan device of the present invention, Fig. 2 is a plan view showing an enlarged view of the main parts thereof, Fig. 3 is a cross-sectional view showing another embodiment, and Fig. 4 is a chip. FIG. 5 is a diagram showing the results of an experiment investigating the relationship between clearance and noise level, and FIG. 5 is a sectional view showing a conventional example. 1...Engine, 2...Radiator (heat exchanger)
, 3... Be cooling) fan, 4... Fan shroud, 5... Connection part, 6... Fan surrounding part (cylindrical part), 7... Fan shaft, 8.8'... Fan of the present invention, 9... Outer surrounding portion, 11... Slit, 13
... Screw, 14... Electric motor, 15...
Arm, 16... Annular frame, 17... Slit, 18... Screw, t, t"... Chip clearance, α, θ, θ'... Inclination angle.

Claims (1)

[Claims] It has a fan for gas circulation placed opposite to the heat exchanger, and a fan shroud that covers the heat exchanger from the back side of the heat exchanger to the outer periphery of the fan to guide the gas flow, and the fan has a blade tip edge thereof. is inclined with respect to the fan axis so as to lie on an imaginary conical surface expanding toward the heat exchanger, and the fan shroud connects the heat exchanger and the fan envelope. The fan envelope portion of the fan shroud has a conical inner surface that is inclined at substantially the same angle as the slope of the blade tip edge of the fan and connected to the connection portion. , the fan and the fan shroud are capable of changing their relative positions in the axial direction, thereby adjusting the size of the gap between them. A fan device attached to.