JPH02130213A - Vehicle cooling device - Google Patents

Abstract

PURPOSE:To make it possible to sustain the cooling effect of a fan while lowering noise by providing, in a shroud, a movable part for limiting the flow of air into the fan, which can be moved axially by the ram pressure of air. CONSTITUTION:Air forward of a heat-exchanger 1 flows through a shroud 3 and is discharged in the rear of a fan 2 due to the ram pressure of air and the action of the fan 2. In this arrangement, a movable part 32 of the shroud 3 receives a pressure produced by the flow of air, and a negative pressure resisting against the former pressure and produced by the exhausting operation of the fan 2 within a space defined by the heat-exchanger 1, the shroud 3 and the fan 2. Further, due to the action of the movable part 32 due to the negative pressure, a small diameter bore 323 in the movable part 32 constituting the shroud 3 can locate the fan 2, relatively in the rear of the bore 323 when the negative pressure is high. Accordingly, the centrifugal air flow from the fan 2 is restrained, thereby it is possible to prevent noise caused by the air flow.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a cooling device for a vehicle, and particularly to a cooling device for a vehicle that includes a heat exchanger and a fan disposed behind the heat exchanger.

[Prior art 1] Conventionally, a vehicle cooling system includes a heat exchanger such as a radiator, a fan placed behind the heat exchanger and which removes heat from the heat exchanger through air flow, and a fan that removes heat from the heat exchanger through the flow of air. A shroud that guides the flow of air into the air is known.

The structure of the shroud that guides the air flow from the heat exchanger to the fan consists of a bellmouth-shaped part that guides the air flow from the heat exchanger to the front end of the fan, and a cylindrical part that covers the outer periphery of the fan. It is fixed as one piece to the rear of the heat exchanger.

[Problems to be Solved by the Invention] Conventional vehicle cooling systems in which the shroud is integrally constructed have a problem in that even if the shroud shape is optimal, the front resistance of the heat exchanger is high when the vehicle is running. is small, and
When the front resistance of the heat exchanger is large, such as during idling, the air flow becomes unstable, and in particular, the latter has the disadvantage that the flow in the centrifugal direction is stronger and the noise is louder than in the former.

The present invention was devised in view of the above-mentioned drawbacks, and provides a cooling system for vehicles that maintains the cooling effect of the fan and has low noise.
The technical challenge is to provide the following.

[Means for Solving the Problems] A vehicle cooling device of the present invention includes a heat exchanger, a fan disposed behind the heat exchanger, and a flow of air from the heat exchanger to the fan. The shroud consists of a tubular fixed part fixed to the heat exchanger, a large diameter part with a wide cross-sectional area that is guided by the fixed part on one end, and a diameter smaller than the outer circumference of the fan on the other end. The fan has a small diameter part with a large narrow cross-sectional area, and a movable part that is movable in the axial direction by the ram pressure of air and regulates the flow of air by the fan.

[Function] With the above configuration, the air in front of the heat exchanger flows out to the rear of the fan through the shroud due to the ram pressure and the action of the fan.

Here, the movable part of the shroud is subjected to pressure due to the pressure due to the air flow and negative pressure created by the exhaust action of the fan in a space defined by the heat exchanger, the shroud, and the fan that opposes the pressure. When this negative pressure is large, that is, when the front resistance of the heat exchanger is large, such as during idling, the movable part is guided by the fixed part and moves forward, that is, in a direction approaching the heat exchanger. On the other hand, when the negative pressure is small, that is, when the front resistance of the heat exchanger is small, such as when the vehicle is running, the movable part moves backward, that is, in a direction away from the heat exchanger. Due to the action of this movable part, when negative pressure is large, the small-diameter part of the movable part that makes up the shroud positions the fan relatively behind the small-diameter part, thereby suppressing the centrifugal air flow caused by the fan. , to prevent noise caused by air flow.

[Example] As shown in FIGS. 1 to 5, the vehicle cooling system of this example includes a heat exchanger 1 and a fan 2 disposed behind the heat exchanger 1.
and a shroud 3 that guides the flow of air from the heat exchanger 1 to the fan 2.

The heat exchanger 1 is generally called a radiator and has a rectangular shape placed behind the grille of a vehicle, and includes a plurality of vibrators through which a heat medium passes and a number of pipes welded parallel to each other at predetermined intervals. The heat exchanger 1 has a large number of air passages formed between adjacent fins in the front-rear direction of the heat exchanger 1.

The fan 2 is an axial fan having a plurality of blades 21, and is rotationally driven by a drive FA (not shown) directly connected in the axial direction. Axial width L+(4th
Figure) uses a 60mm one.

The shroud 3 consists of a fixed part 31 fixed to the heat exchanger 1 and a movable part 32.

The fixing part 31 has a tubular shape with a substantially rectangular outer edge that is directly connected to and fixed to the rear outer edge of the heat exchanger 1, and is provided at several locations on the inner circumferential surface as shown in FIG.
A trapezoidal groove 31 whose bottom is wider than the opening width as shown in FIG.
1 is carved in the axial direction.

The movable part 32 has a short tubular large diameter part 321 having a substantially rectangular outer edge aligned with the inner peripheral surface of the fixed part 31 on one end side, and one end is integral with the large diameter part 321 and the other end is slightly longer than the outer circumference of the fan 2. It consists of a bell mouth part 322 formed into a large circular funnel shape, and a small diameter part 323 that is integral with the other end of the bell mouth part 322 and covers the outer periphery of the fan 2. The large diameter portion 321 has a trapezoidal protrusion 321a (FIG. 5) that engages with the groove 311 of the fixing portion 31 and extends in the axial direction.

Also, near the rear end of the small diameter portion 323, there is a differential user part 3 in which the opening cross-sectional area increases as it advances toward the rear end forming an angle α in FIG.
It has 23a.

'The static pressure characteristics of the fan 2 employed in this embodiment are shown in FIG. Here, the distance between the rear end of the heat exchanger and the front edge of fan 2 is 1 (
(shown in FIG. 4) is 20 mm. The horizontal axis is the wind! (m3/
hr), and the vertical axis is the static pressure (mmAq) in the space surrounded by the heat exchanger 1, fan 2, and shroud 3. The characteristics of the fan 2 when the ventilation resistance of the heat exchanger 1 is different are shown in equations.

Note that ■, ■, and IV are reference examples showing the static pressure characteristics of the heat exchanger 1 when the type of the heat exchanger 1 is IC.

The distance 111L (Fig. 4) from the rear end of the heat exchanger 1 to the rear end of the bell mouth part 322 is the distance 111L (Fig. (state of large resistance), L-20mm, static pressure 4.75
At the time of low ventilation resistance of mmAq (a state where the front resistance of the heat exchanger 1 is small, such as when driving), it is desirable that it is L-50 mm. This varies depending on the shape of the fan 2, etc. Therefore, the movable width L2 (FIG. 4) of the groove 311 is set to 3Qmm. This length Lt corresponds to approximately one-half of the axial width L+-60 mm of the tip of the blade 21 of the fan 2.

On the other hand, the length of the small diameter part 323 of the movable part 32 is Lt-60m.
The length is approximately the same as m. Deaf user part 32
The length Ll of 3a (Fig. 4) is 20, which is one-third of Ll.
mm, and the angle α (FIG. 4) was 7°.

To attach the movable part 32 to the fixed part 31, before attaching the fixed part 31 to the heat exchanger 1, engage the protrusion 321a of the movable part 32 with the groove 311 of the fixed part 31 from the front of the fixed part 31. This is done by fitting and inserting the movable part 32 at the same time. Needless to say, the fixed part 31 is attached to the heat exchanger WA device 1 with the movable part 32 fitted into the fixed part 31.

The operation of this embodiment will be explained below.

Air in front of the heat exchanger 1 passes through the shroud 3 and flows out behind the fan 2 due to the ram pressure and the action of the fan 2.

Here, the movable part 32 of the shroud 3 is subjected to a force due to the pressure due to the air flow and the negative pressure generated in the space formed by the heat exchanger 1, the shroud 3, and the fan 2 that resists the pressure.

When this negative pressure is small (for example, 4.75 mmAq), that is, when the front resistance of the heat exchanger 1 is small such as when the vehicle is running, the pressure due to the air flow is greater than the negative pressure, so the movement is as shown in Fig. 2. In the portion 32, the protrusion 321a slides on the groove 311 and moves rearward (to the position of L-50 mm).

On the other hand, when the negative pressure is large (e.g. 8.25 mmAq)
That is, in a state where the front resistance of the heat exchanger is large such as when idling, the internal pressure is higher than the pressure due to the air flow, so the movable part 32 has a protrusion 321a that slides in the groove 311 as shown in FIG. Move to the front (L-20mm position) vJ
do.

At this time, SPL (sound level) is shown in FIG.

In Figure 7, the horizontal axis is L (mm) and the vertical axis is SPL (unit: d
B> is the result of comparing the influence on noise due to the positional relationship between L and the blade 21 in the same case. Here V
shows the SPL characteristics of this example.

Incidentally, VllVl and ■ indicate the characteristics when the airflow is constant at high ventilation resistance, medium ventilation resistance, and low ventilation resistance, respectively.

As can be seen from FIG. 7, the movement of the movable part 32 suppresses the centrifugal flow of air within the shroud 3 not only when the negative pressure is small but also when the negative pressure is large. Prevent noise caused by flow.

[Effects] The vehicle cooling device of the present invention has a shroud that has a tubular fixed part fixed to a heat exchanger, one end of which is guided by the fixed part, the other end of which covers the outer periphery of the fan, and which is rotated in the axial direction by the ram pressure of air. Since the movable part is movable to regulate the air flow to the fan, the movable part is moved by the ram pressure and the negative pressure inside the shroud, and not only maintains the cooling N1 effect of the fan, but also can suppress noise to a lower level than fixed ones.

4. Drawing ll! '1lJ1 Explanation Figures 1 and 2 show the vehicle cooling system of this embodiment.
The figure shows a case where the negative pressure inside the shroud is large, and FIG. 2 is an explanatory drawing when the negative pressure is small. 3 is a partial front view of the vehicle cooling system of this embodiment, FIG. 4 is a view taken along the line AA in FIG. 3, and FIG. 5 is a sectional view taken along line BB in FIG. 4. FIG. 6 is a graph showing the static pressure characteristics of this example, and FIG. 7 is a graph showing the AI sound level (S P L ) of this example.

1...Heat exchanger 2...Fan 3...Shroud 31...Fixed part 32...Movable part Patent applicant Nippondenso Co., Ltd.

Claims (1)

[Claims] (1) A vehicle cooling device comprising a heat exchanger, a fan disposed behind the heat exchanger, and a shroud that guides the flow of air from the heat exchanger to the fan, wherein the shroud a tubular fixed part fixed to the exchanger, a large diameter part with a wide cross-sectional area guided by the fixed part on one end side, and a small diameter part with a narrow cross-sectional area slightly larger than the outer diameter of the fan on the other end side. 1. A cooling device for a vehicle, comprising: a movable part that is movable in the axial direction by the ram pressure of air and regulates the flow of air by the fan.