JP2697023B2 - Vehicle cooling system - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vehicle cooling device, and more particularly to a vehicle cooling device including a heat exchanger and a fan disposed behind the heat exchanger.

[Prior art] Conventionally, a vehicle cooling device includes a heat exchanger such as a radiator,
There is known a fan which is disposed behind the heat exchanger and removes heat of the heat exchanger by the flow of air, and a shroud which guides the flow of air from the heat exchanger to the fan.

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

[Problem to be Solved by the Invention] The above-described shroud has a function of guiding an air flow from a heat exchanger to a fan and a function of smoothly blowing air from the fan. In the above-described conventional vehicle cooling device, the flow of air in the shroud is significantly different depending on whether the ram pressure is large, such as when the vehicle is running, or when there is no or small ram pressure, such as during idling.

Therefore, when the shroud is fixed, when the ram pressure changes, the streamline in the shroud changes, and the fluid loss inside the shroud and the amount of noise generated thereby change. In other words, even if the shroud shape is ideally designed to have the lowest loss or low noise with respect to the airflow when there is no ram pressure, if the ram pressure increases during high-speed running, the shroud shape will be in this state. This greatly deviates from the ideal state at the time, resulting in an increase in loss and noise.

The present invention has been made in view of the above problems, and an object of the present invention is to provide a vehicle cooling device capable of reducing fluid loss and noise regardless of a change in ram pressure.

Means for Solving the Problems A vehicle cooling device of the present invention guides a heat exchanger, a fan disposed behind the heat exchanger, and a flow of air from the heat exchanger to the fan. In a vehicle cooling device including a shroud, the shroud comprises: a tubular fixing portion fixed to the heat exchanger; one large end portion having a large diameter guided by the fixing portion; It has a small-diameter portion that is smaller in diameter than the large-diameter portion and surrounds the fan in an annular manner with a small gap therebetween, and has a movable portion that is displaced in the axial direction by ram pressure due to vehicle running.

In a preferred aspect of the present invention, the small-diameter portion has a diffuser portion extending rearward, and a front end of the fan is displaced to a position protruding forward from the small-diameter portion when a small ram pressure is applied. And, at the time of large ram pressure, it retreats inside the small diameter portion, the rear end of the fan is displaced to a position protruding backward from the small diameter portion at the time of small ram pressure, and at the time of large ram pressure, A configuration of moving forward inside the part is adopted.

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

Here, the movable part of the shroud receives the pressure due to the flow of air and the negative pressure created by the exhaust action of the fan in the space defined by the heat exchanger, the shroud and the fan. As in idling, the ram pressure is low, so the space between the fan and the heat exchanger due to the suction of the fan (hereinafter also referred to as the fan front space)
The static pressure (negative pressure) of the shroud increases, and the movable part of the shroud moves forward, that is, in the direction approaching the heat exchanger, by the action of this pressure.

On the other hand, when the ram pressure is large and the static pressure in the space in front of the fan is small, for example, when the vehicle is running, the dynamic pressure of the airflow acting on the movable part of the shroud is affected. Move away from

Next, the effect of the above-described movement of the movable portion of the shroud on the airflow in the shroud will be described.

First, consider the case where the ram pressure is large, such as when the vehicle is running.

In this case, since the ram pressure that increases the axial velocity component of the air flow is large, the axial velocity component of the air flow blown from the fan is the centrifugal velocity generated by the centrifugal force of the air flow and the fan blade shape. As a result, the velocity component (streamline) of the airflow blown from the fan has a shape lying in the axial direction. Therefore, by retracting the movable portion of the shroud as in the present invention, a portion of the movable portion extending rearward from the rear end of the fan (also referred to as a rearward projecting portion) becomes longer,
As a result, the effect of rectifying the airflow blown out from the fan by the shroud is improved. In addition, a space is newly formed on the front outer peripheral side of the fan due to the retreat of the movable portion of the shroud, so that the air flow can flow from the heat exchanger to the fan through the space, and the air flow suction function of the fan is improved. As a result, the processing air flow rate of the fan increases. In addition,
Forcibly bending the flow of the air, i.e., the streamline, at a large flow rate increases the fluid loss, which translates into heat and noise. For example, the air flow exiting the heat exchanger can be drawn in from the outer periphery of the front end of the fan. As a result, fluid loss and noise in the shroud are reduced.

Next, a case where the ram pressure is small as in idling will be considered.

In this case, since the ram pressure that increases the axial velocity component of the airflow is small, the axial velocity component of the airflow blown from the fan is opposite to the above, due to the centrifugal force of the airflow and the fan blade shape. As a result, the velocity vector (stream line) of the airflow blown out from the fan has a shape that stands in the radial direction. Therefore, by moving the movable portion of the shroud forward as in the present invention, a portion of the movable portion extending rearward from the rear end of the fan (also referred to as a rearward projecting portion) is shortened, and the airflow blown out of the fan is correspondingly reduced. However, the rate of occurrence of fluid loss and noise due to collision with the inner surface of the rear protruding portion is reduced.

In other words, when the vehicle travels when the velocity vector of the airflow blown from the fan lies in the axial direction (when the ram pressure is large), the movable portion protrudes the movable portion of the shroud to the rear of the fan to perform rectification and pressure conversion. During idling, when the velocity vector of the airflow blown out from the fan is relatively radial (when the ram pressure is small), the blown airflow does not protrude much toward the rear of the fan and the airflow blows out. The turbulence and noise when colliding with the inner surface of the vehicle are reduced.

Further, the forward movement of the movable portion of the shroud eliminates the space on the outer peripheral side of the front of the fan, so that no airflow flows through the space from the heat exchanger to the fan. The air flow can be sucked in from the front side of the fan, and the loss of the fan can be reduced at a small flow rate.

[Embodiment] As shown in Fig. 1 to Fig. 5, a vehicular cooling apparatus according to this embodiment includes a heat exchanger 1, a fan 2 disposed behind the heat exchanger 1, and a fan 2 And a shroud 3 for guiding the flow of air to the shroud 3.

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

The fan 2 is an axial fan having a plurality of blades 21 and is rotationally driven by a driving unit (not shown) directly connected in the axial direction. The axial width L ₁ of the tip of the blade 21 (Fig. 4) is 60
mm.

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

The fixing portion 31 is a tubular member having a substantially rectangular outer edge which is directly connected to and fixed to the rear outer edge of the heat exchanger 1 and has a trapezoidal shape having a bottom wider than the opening width as shown in FIGS. Groove 311 is cut in the axial direction.

The movable portion 32 has a short tubular large-diameter portion 321 having a substantially rectangular outer edge aligned with the inner peripheral surface of the fixed portion 31 on one end side, a large-diameter portion 321 at one end, and one end slightly above the outer periphery of the fan 2. Bell mouth part 32 formed in a funnel shape to form a large circle
2 and a small-diameter portion 323 that covers the outer periphery of the fan 2 integrally with the other end of the bell mouth portion 322. Large diameter part 321 is fixed part
A protrusion 321a extending in the axial direction with a trapezoidal shape engaging with the groove 311 of 31
(Fig. 5). In the vicinity of the rear end of the small-diameter portion 323, a fourth
A diffuser portion 323a has an opening cross-sectional area that increases toward the other end forming the angle α in the drawing.

FIG. 6 shows the static pressure characteristics of the fan 2 employed in this embodiment. Here, the distance l (shown in FIG. 4) between the rear end of the heat exchanger and the front edge of the fan 2 is 20 mm. The horizontal axis is the air volume (m ³ / hr), and the vertical axis is the static pressure (mmAq) in the space surrounded by the heat exchanger 1, the fan 2, and the shroud 3. The characteristics of the fan 2 when the ventilation resistance of the heat exchanger 1 is different are indicated by I.
II, III, and IV are reference examples showing the static pressure characteristics of the heat exchanger 1 when the types of the heat exchanger 1 are different.

The distance L (FIG. 4) from the rear end of the heat exchanger 1 to the rear end of the bell mouth portion 322 is high when the static pressure is 8.25 mmAq (when the front resistance of the heat exchanger 1 is large when idling or the like). It is preferable that L = 20 mm in the state (L) and L = 50 mm in the case of low ventilation resistance with a static pressure of 4.75 mmAq (a state in which the forward resistance of the heat exchanger 1 is small such as during running). This depends on the shape of the fan 2 and the like. Therefore, the movable width L _{2 of the} groove 311 (FIG. 4) is 3
0 mm. The length of this L ₂ is blade 21 of fan 2
This corresponds to about _{one half} of the axial width L _{1 of the} tip = 60 mm.

On the other hand, the length of the small-diameter portion 323 of the movable portion 32 is substantially the same as L ₁ = 60 mm. Length of diffuser part 323a
L ₃ (FIG. 4) is 20 mm, which is one third of L ₁ , and the angle α
(FIG. 4) was set to 7 °.

The method of attaching the movable part 32 to the fixed part 31 is such that the protrusion 321a of the movable part 32 is engaged with the groove 311 of the fixed part 31 from the front of the fixed part 31 before attaching the fixed part 31 to the heat exchanger 1. This is performed by inserting the part 32. It goes without saying that the fixed part 31 is attached to the heat exchanger 1 in a state where the movable part 32 is fitted into the fixed part 31.

 The operation of this embodiment will be described below.

The 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 portion 32 of the shroud 3 receives the pressure due to the flow of air and the force against the pressure due to the negative pressure formed in the space formed by the heat exchanger 1, the shroud 3 and the fan 2.
When the negative pressure is small (for example, 4.75 mmAq), that is, when the forward resistance of the heat exchanger 1 is small, such as when the vehicle is running, the pressure due to the flow of air is larger than the negative pressure. 32, the protrusion 321a slides along the groove 311 and moves rearward (L = 5
(0mm position). On the other hand, when the negative pressure is large (for example, 8,25 mmAq), that is, in a state where the forward resistance of the heat exchanger is large at the time of idling or the like, the negative pressure is larger than the pressure due to the flow of air. The portion 32 moves forward (the position of L = 20 mm) by the protrusion 321a sliding in the groove 311.

At this time, the SPL (noise level) is shown in FIG. In FIG. 7, the horizontal axis represents L (mm) and the vertical axis represents SPL (unit: dB).
9 is a result of comparing the influence on noise due to the positional relationship between the blade and the blade 21 at the same airflow. Here, V indicates the characteristics of the SPL of the present embodiment. Note that VI, VII, and VIII indicate the characteristics when the air volume 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 portion 32 suppresses the flow of air in the centrifugal direction in the shroud 3 not only when the negative pressure is low but also when the negative pressure is high, and this air flow is reduced. Prevent noise caused by

[Effects] As described above, since the shroud of the vehicle cooling device of the present invention includes the movable portion that is displaced in the axial direction due to a change in the ram pressure caused by running of the vehicle, fluid loss and noise can be reduced. Can be.

In other words, when the ram pressure is large, such as when driving a vehicle,
Due to an increase in the axial velocity component of the airflow blown from the fan, the velocity vector has a shape lying in the axial direction. Therefore, by retracting the movable portion of the shroud as in the present invention, the portion of the movable portion extending rearward from the rear end of the fan becomes longer, and accordingly, the airflow blown out of the fan is sufficiently reduced by the movable portion of the shroud. Rectification and pressure conversion. In addition, since the movable portion of the shroud retreats, a new space is formed on the front outer peripheral side of the fan,
Airflow can flow from the heat exchanger to the fan through this space, improving the airflow suction of the fan and reducing losses and noise in the airflow suction.

Also, when the ram pressure is low, such as during idling, the velocity vector in the axial direction of the airflow blown out from the fan is small, so that the velocity vector has a shape that stands in the radial direction.
Therefore, by advancing the movable portion of the shroud as in the present invention, the portion of the movable portion extending rearward from the rear end of the fan is shortened, and accordingly, the blown air that stands relatively in the centrifugal direction from the fan. The rate at which the flow impinges on the inner surface of the rearward projecting portion and generates fluid loss and noise is reduced. Further, the forward movement of the movable portion of the shroud enables the fan to suck the airflow from the front side of the fan, which is the most efficient when the flow rate is small, and can reduce the loss of the fan when the flow rate is small.

[Brief description of the drawings]

FIGS. 1 and 2 show a vehicle cooling system according to the present embodiment.
FIG. 2 is an explanatory diagram when the negative pressure in the shroud is large, and FIG. 2 is an explanatory diagram when the negative pressure is small. FIG. 3 is a partial front view of the vehicle cooling device of this embodiment, FIG. 4 is a view taken along the line AA of FIG. 3, and FIG. 5 is a sectional view taken along the line BB of FIG. FIG. 6 is a graph showing the static pressure characteristics of this embodiment, and FIG. 7 is a graph showing the noise level (SPL) of this embodiment. 1 ... heat exchanger, 2 ... fan 3 ... shroud, 31 ... fixed part 32 ... movable part

Claims (2)

(57) [Claims] 1. A vehicular cooling system comprising a heat exchanger, a fan disposed behind the heat exchanger, and a shroud for guiding air flow from the heat exchanger to the fan, wherein the shroud is A tubular fixing portion fixed to the heat exchanger, one end of which comprises a large-diameter large-diameter portion guided by the fixing portion, and the other end is smaller in diameter than the large-diameter portion and separated by a small gap. A cooling device for a vehicle, comprising: a movable portion having a small-diameter portion surrounding a fan in an annular shape, and being displaced in an axial direction by ram pressure due to vehicle running. 2. The small-diameter portion has a diffuser portion extending rearward, and a front end of the fan is displaced to a position protruding forward from the small-diameter portion when a small ram pressure is applied. At the time of ram pressure, it retreats to the inside of the small diameter portion, the rear end of the fan is displaced to a position protruding backward from the small diameter portion at the time of small ram pressure, and inside the small diameter portion at the time of large ram pressure. The vehicle cooling device according to claim 1, wherein the vehicle cooling device moves forward.