JPS599760B2 - cooling fan - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a cooling fan having blades fixed at a predetermined pitch angle to a boss connected to a drive source.

For example, in an automobile engine cooling fan, a plurality of blades are attached to the outer peripheral wall of a boss at a predetermined pitch angle, and the boss is fixed to a rotating shaft connected to an engine drive source.

When this type of cooling fan rotates at high speed, the horsepower consumption increases due to air resistance against the blades, noise is generated, and the object to be cooled may be overcooled.

So-called flexible fans made of resin have conventionally been used to prevent such troubles.

This flexible fan uses the flexibility of resin blades to reduce the pitch angle of the blades due to air resistance during high-speed rotation, thereby preventing the above-mentioned problems.

However, in this flexible fan, the blades and the boss are integrally constructed, and the decrease in pitch angle during high-speed rotation depends exclusively on the flexibility of the blades, so the amount of reduction cannot be large enough, and the shape of the blades Depending on the dimensions, part of the blade may break during high-speed rotation.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a cooling fan whose pitch angle is variable according to the rotational speed without the above-mentioned problems, thereby achieving reductions in horsepower consumption and noise, and prevention of overcooling. And by controlling the pitch angle according to temperature conditions. The objective is to achieve an appropriate cooling state.

In order to achieve the above object, the cooling fan of the present invention has a through hole bored in the radial direction of the boss on the outer periphery of the boss connected to the drive source, through which a shaft member provided at the base end of the blade can be rotated. The shaft member and the through hole are respectively connected by a first elastic member and a second elastic member which is more rigid than the elastic member and has a smaller rate of change in torsional rigidity with respect to temperature changes.

A torsional load is applied to the first elastic member in advance, which imparts a rotational moment to the shaft member in the direction of decreasing the pitch angle of the blades, which is balanced with the elastic force of the second elastic member that resists this. The blades are held at a predetermined pitch angle.

However, when the cooling fan rotates at high speed, when the blades are subjected to air resistance, the balance shifts and the blades are inclined in a direction in which the pitch angle decreases with respect to the boss.

However, as the temperature rises, the rotational moment of the second elastic member in the opposite direction to the rotational moment of the first elastic member in the pitch angle decreasing direction becomes relatively large.

Therefore, the rate of decrease in the pitch angle of the blades due to high speed rotation is smaller than that at low temperatures, and the cooling effect at high temperatures is stronger than at low temperatures.

In other words, a cooling effect corresponding to the temperature conditions is exhibited.

The details of the present invention will be explained below with reference to an embodiment of an engine cooling fan shown in FIGS. 1 and 2.

In FIG. 1, reference numeral 1 denotes a boss, which is bolted and fixed through a bolt hole 11 to a pulley (both not shown) that is driven by the crankshaft of the engine via a fan belt.

2 is a blade, and a shaft member 21 has a rivet 2 at one end thereof.
It is fixed by 2.

Two through holes 12 (only one shown in the figure) are bored in the radial direction at opposing positions on the outer periphery of the boss 1, and a fixing fitting 13 is covered and fixed to the outer opening of the through hole. The shaft member 21 is inserted into the boss 1 through the opening provided in the center of the metal fitting 13.
is rotatably inserted into the through hole 12 of.

The shaft member 21 is fixed to one end of the blade 2 and inserted into the through hole 12 of the boss 1. Insert fittings 26, 27 are fitted by serrations to the tip of the shaft member 21, and the shaft end is fixed by screws 24 or the like. A push 35 (first elastic member) made of a rubber-like elastic body is sandwiched between the fixing fitting 13 and the insert fitting 27 on the outer periphery of the shaft member 21, and both end surfaces of the push 35 are connected to the fittings 13, 27. glued in between.

Furthermore, a metal torsion coil spring 36 (second elastic member) is installed around the outer periphery of the pusher 35, and both ends of the spring are latched by clasps (not shown) provided on the insert fitting 26 and the fixing fitting 13. ing.

In this way, both the elastic members 35 and 36 independently couple the boss 1 and the shaft member 21.

The metal torsion coil spring 36 has higher torsional rigidity than the rubber-like elastic pusher 35, and the rate of change in torsional rigidity with respect to temperature changes is smaller.

The push 35 is biased in the counterclockwise direction (pitch angle decreasing direction) by applying a clockwise torsional load as viewed from the direction of the arrow X in FIG. Due to the elastic force, the shaft member 21, and therefore the blade 2, receive a torsional load in the clockwise direction, and as shown in FIG. 262, and the pitch angle of the blade 2 is set at this position.

When the fan rotates, when the blades 2 receive a twisting moment due to centrifugal force and wind pressure, a counterclockwise twisting moment acts on the insert fitting 26 that is integrated with the shaft member 21, and the insert fitting 26 is fixed to the fitting 26 via the fitting 27. The pushed push 35 undergoes torsional deformation, making it possible to reduce the pitch angle of the blade 2.

Therefore, the rate of decrease in torsional rigidity of the rubber elastic pusher 35 due to temperature rise is greater than that of the metal torsion coil spring 36; The combined moment of the metal torsion coil spring 36 and the pusher 35 resisting the rotational moment of the blade 21 is greater at high temperatures than at low temperatures, and the decrease in the pitch angle of the blades 2 is suppressed.

Therefore, when an object to be cooled such as an engine placed close to the fan becomes high temperature, the degree of decrease in the pitch angle of the blades is correspondingly suppressed, and the cooling effect can be enhanced compared to when the temperature is low. be.

The above operation will be explained with reference to FIG.

In the figure, △θ is the pitch angle decrease amount of the blade during rotation, T is the torsional moment (A) is the direction of pitch and angle increase,
(@ indicates the direction of decreasing pitch angle.

Therefore, the E line is the torsional moment due to the metal coil spring acting in the direction (A), and the torsional moment due to the rubber elastic body push acts in the opposite direction.

The torsional moment due to this push is smaller at high temperatures (G' line) than at low temperatures (G line) [On the other hand, the torsional moment of a metal torsion coil spring hardly changes depending on temperature, so the resultant moment in direction (1) is smaller at high temperatures. (F
line) is more dog-like than at low temperature (F' line).

Note that H is the initial torsional load at low temperatures, and J is the initial torsional load at high temperatures. With this initial torsional load applied, the pitch angle of the blade is set by the stopper 15 in FIG. 9.

For example, in the case of an engine cooling fan, when the engine cooling water temperature rises, the torsional rigidity of the rubber elastic body push decreases due to the thermal effect, and as a result, as shown in Figure 3, the resultant moment becomes more sharp than at low temperatures, and the blades The degree of decrease in the pitch angle is suppressed compared to when the temperature is low, so that the cooling capacity can be maintained relatively high and the cooling water can be maintained at an appropriate temperature.

As described above, the present invention automatically varies the pitch angle of the blades in response to the centrifugal force acting on the blades and the torsional moment due to wind pressure when the fan rotates, especially at high speeds, thereby reducing drive power consumption and noise. It is possible to reduce the temperature and prevent overcooling of the object to be cooled.

In particular, in the present invention, the vane and the boss are respectively connected by a first elastic member and a second elastic member made of a material that is more rigid than the first elastic member and has a smaller rate of change in torsional rigidity with respect to temperature changes, and both elastic members Since the pitch angle of the blade is set while balancing the rotational moment in the opposite direction that the member applies to the blade, it is possible to control the cooling capacity of the blade in accordance with the temperature conditions and maintain the object to be cooled at an appropriate temperature. .

[Brief explanation of drawings]

FIG. 1 is a partially cutaway front view showing the main parts of an embodiment of the present invention;
FIG. 2 is a sectional view taken along the line ■--■ in FIG. 1, and FIG. 3 is a diagram showing the operation of the fan of the present invention. 1...boss, 2...feather, 21...
...Blade shaft member, 35...First elastic member, 36...Second elastic member.

Claims (1)

[Claims] 1. In a cooling fan in which blades are installed at a predetermined pitch angle on the outer periphery of a boss connected to a drive source, a shaft member formed at the base end of the blade has a through hole drilled radially from the outer periphery of the boss. the shaft member and the through-hole wall in a first
an elastic member having a stiffness greater than that of the first elastic member;
and a second elastic member made of a material with a small rate of change in torsional rigidity with respect to temperature changes, respectively, and a torsional load is applied to the first elastic member in advance to rotate the blade in the direction of decreasing the pitch angle. A cooling fan characterized in that a moment is applied to a shaft member, and the blades are held at a predetermined pitch angle in balance with the elastic force of a second elastic member that resists the moment.