DE3044307A1 - IC engine radiator cooling fan - has blades made of temp. sensitive material to increase flow by varying blade angle as temp. rises - Google Patents

Abstract

The arrangement is intended for automatically varying the output flow of a rotating (4) cooling fan as a function of temp. particularly for a motor vehicle engine radiator, by varying the fan blade angle. The fan blades (1) consist of a temp-sensitive material or of layers of metals with different thermal expansion, at least in their fixing areas (2,3). The blades may consist of 'memory metal', i.e. a copper-aluminium zinc alloy. The variable-curvature blade area may be reinforced by a single or multi-element (5-6) leaf spring. The element (5-6) may be different in length.

Description

M.A.N. MASCHINENFABRIK AUGSBURG-NÜRNBERG Aktiengesellschaft

Nuremberg, November 22, 1980

Device for automatic temperature-dependent regulation of the amount of cooling air conveyed by a fan

The invention relates to a device for the automatic temperature-dependent control of amount of cooling air conveyed by a fan. In particular is the device according to the invention in connection with the regulation of the cooling air flow rate with a Fan-provided radiator of a motor vehicle or the like. Determined.

In the case of water-cooled vehicle engines, both diesel and Otto engines, the entire thermal power dissipation (with the exception of the exhaust gas heat) is essentially dissipated by the cooler. It is customary to use the air side of the engine-external, normally exposed to the airstream A fan must be provided for the cooler, which provides the necessary additional forced convection. The Convection must be such that it is the in each

RP 22.8745

f.

the

] Phase motor load / the cooling circuit can safely dissipate power loss. From it
it follows that a fan rotating at a fixed speed with the crankshaft of the engine in such operating cases.

those of high speed. lower outside

temperature and low engine load
generate higher cooling air flow rates than that
Heat loss is actually necessary accordingly
were.

The mechanical excess power supplied to the fan in such a case is undesirable because it causes the
Fuel consumption of the engine increased unnecessarily and possibly j

cools the motor too much, which reduces the efficiency of the '

Combustion is reduced. j

To prevent such a condition from occurring, 1

it has already been suggested that the fan

setting the amount of cooling air by using a regulating j

able fan to automatically adapt to the heat load on the cooling circuit j.

The air throughput can thereby, for example, be reduced regulates that the fan switches on and off depending on the temperature!

off or toggled. This means,
that clutches must be provided that ever

according to the design, the torque positive or non-positive I

sig from the drive shaft to the fan.
The function of the couplings is to

that when too high a cooling water temperature is reached via a suitable temperature-controlled

- 3 04 A 3

] Actuator of the clutch engagement in one the speed increasing sense of the fan is initiated. This can lead to the realization of a form-fitting working Control coupling an electromagnetic coupling acting according to the two-point control principle can be provided.

If the cooling water target temperature is slightly exceeded or not reached the electromagnetic clutch is energized or de-energized and accordingly the Fan on or off. A disadvantage of such an arrangement is the inevitable wear at the magnetic poles, which at the same time have the surfaces that transmit the torque. The ones from Power loss caused by wear occurs during

"15 of the fan, because of the inevitable Speed slip between fan and drive shaft during the acceleration phase.

In such an arrangement, the jerky acceleration surges that the fan blades also disturb Strongly stress in terms of strength in the vicinity of the hub, which may lead to life-reducing effects.

If you use force-fit working, hydraulic clutches, then there is no mechanical wear and this is power loss occurs directly in the form of heat. The use of hydraulic clutches allows also to control the degree of coupling externally and thus by means of a temperature-dependent control the

22.8745

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Fan speed and thus the one that penetrates the cooler Amount of cooling air the current loss of heat adapt in the water circuit of the engine.

A disadvantage of such a control by means of a hydraulic clutch is that which always occurs Slip performance. This is released as heat loss in the hydraulic oil, so it must ultimately be used by the engine as lost power will be applied.

10

In order to completely prevent the occurrence of power loss without a continuous control behavior To interfere, it was proposed to use the fan blades - in the manner of a controllable pitch propeller to adjust a rack and pinion system depending on the temperature so that that of the respective Temperature corresponding air throughput is reached. As an actuator for the rack and pinion system and thus the Aas-be.llv * inkÄl of the fan blades a helical spring-like structural part in the hub that expands axially depending on the temperature of the fan arranged, whereby it is directly exposed to the exhaust air flow of the cooler and thus to temperature-dependent control is suitable. This actuator then acts directly on the fan blade angle determining * racks.

Here, a metal alloy was proposed as a temperature-dependent actuator, such as her known as "memory metal". This

22.8745 ORIGINAL INSPECTED

35

Memory metal is an alloy of copper, zinc · and Aluminum and is subject to intense deformation from a certain temperature, within one very small temperature range that is used to adjust the fan blade angle.

A characteristic of this temperature-selectively controllable actuator made of memory metal is the development unusually large forces that are about 200 times greater than the forces that act on it Place in itself usable bimetal element able to develop approximately the same dimensions. This depends together with the fact that the aforementioned alloy with so-called shape memory is up to 10 times more elastic than common alloys. A cooling system with a fan of the embodiment described above is true as far as possible all control-related requirements. In terms of mechanical robustness, however such a fan is unsuitable for many uses.

Also the mechanical effort for adjustment and thus ultimately susceptibility to failure and manufacturing costs make widespread use of this fan and thus this control principle impossible. The rack and pinion drive itself, but also the fan blade bearing

are the weak points in the mentioned system.

The object of the invention is to provide a fan device with a simple structure in the case of velcher Control principle of the adjustability of the angle of attack

30th

the fan blades is retained without being used

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ORIGINAL INSPECTED

complicated mechanical, wear and tear under I

lying actuators. . i

This task is carried out with a device with the j

Features of claim 1 solved. Where j

it is particularly advantageous, as in claim 2 _f

characterized, the fan blades at least in one j

clamping area made of a metal with memory j

like to form a so-called memory metal. [

j

Further advantageous structural configurations and inventive developments are the subject of the
Subclaims 3 to 6.

'5 With a device for automatic temperature reduction t

pending rules of the cooling conveyed by a fan

air volume are therefore according to the proposal according to the?

Invention of the fan blades themselves from one >

temperature-dependent deforming material manufactured, f

^ ^υ where the material is used in such a way that |

higher temperatures the fan blades in the sense of a> deform higher delivery rate. It is enough

the fan blades only in the clamping area |

to manufacture from such a metal, because this

the angle of incidence of the fan blades itself is changed depending on the temperature.

In terms of manufacturing and strength, however, it is

the fan blades are particularly advantageous in their shape

totality, at least one-sided, from the aforementioned

ft * * i- * • t * * · ♦
I · * »* ft *

■ j deforming as a function of temperature, ie temperature-sensitive To manufacture metal.

As already mentioned, it is particularly advantageous to use a metal as the metal for the fan blades

temperature-controlled shape memory, so to use so-called memory metal, as this once is particularly robust and, moreover, a very intense Ver-IQ at a certain absolute temperature undergoes formation within a very small temperature range. Of course you can at this point any other temperature-sensitive material with sufficient strength can also be used.

In any case, the actuator function is used to set the angle of attack of the fan blades and thus for the cooling air throughput taken over by the fan blades themselves.

Since the heated cooler outlet air when passing the fan, the fan blades are at almost the same temperature heats up, perfect temperature control is also possible in this way.

When using a memory metal to build the fan blades, this means that when a certain value of the fan blade temperature (and thus the cooling water temperature) the fan blades spontaneously are curved, the time sequence of the curvature being essentially dependent on the heating rate depends on the fan blade material. There are those

22.8745

Fan blades below the response temperature completely

just what corresponds to an air capacity of zero. :

At the moment of exceeding the corresponding!

the selected response temperature, the fan

leaves, whereby the conveyed air volume according to j

is increased. When using a memory metal, ι

where the temperature range that is required to I

the fan blades from the completely flat state to the j

Area of greatest curvature and thus the highest conveying capacity · \ ι like to transfer, about 10 ⁰ C or less. j

ORIGINAL INSPECTED

According to a particularly advantageous development f

it is suggested to achieve a higher temperature sensitivity of the fan blades (change of the

Curvature per ⁰ C) the fan blade an "educational |

spring "to be connected in parallel, which creates a counterforce j

testifies to the temperature-related constraint of the sheet->

resistance to curvature. According to the \

Theory of temperature memory

Cu-Al-Zn alloy reacts the actuator in one

such a case with a greater yield of curvature at j

equal temperature change of the radiator blades j

surrounding exhaust air. The use of such a J

The advantage of the spring is that the speed-dependent

the sensitivity to temperature of the

Fan ring is reduced. This speed-dependent it
is a consequence of the attack on the fan blade profile,
speed-related swirl forces of the flow.

// M According to a further development of the aforementioned improvement, it is advisable to subdivide it into several individual elements in order to exclude the risk of breakage of the training spring in the area of the restraint. According to another development, the division of this spring can also be used for local control of the course of the curvature of the individual fan blade in accordance with a flow profile optimization. 10

Details of the construction of a fan blade for a device according to the invention are given below explained in connection with the accompanying drawings.

In these drawings show:

1 shows a single fan blade to explain the basic principle of the device according to the invention,

2 shows a diagram to explain the mode of operation,

3 shows the sectional view of a fan blade with a divided training spring, 4 shows a plan view of a representation according to FIGS. 3 and

Fig. 5 shows a further design option in

Connection of a fan blade with a multi-part training spring.

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In the figures, 1 denotes in each case a fan blade made of a memory metal, which is fastened in a connecting web 2 to the fan hub by means of a Nied 3 is. The movement of the fan blade, a majority of which are arranged on the circumference of a fan hub is indicated by the arrow 4. The heated cooling air meets, as additionally indicated by arrows in Fig. 1, perpendicular to the fan blades.

From Fig. 1 it can be seen immediately that in the cooled state up to a temperature t the single fan blade 1 is elongated. I.

Above the response temperature t, the off '> begins

a>

a memory metal fan blade like i

dashed with 1 'to bend, whereby r:

the air throughput through the fan itself is increased accordingly. The highest curve is t reached at the final temperature, said final temperature t as the response temperature plus 10 ⁰ C, ie t + entspreicht 10 ⁰ C. The position assumed here by the fan blade is also shown in dashed lines in FIG. 1 and with. 1 ".

In the diagram in Fig. 2, the temperature of a fan blade is shown along the abscissa, while the Ordinate indicates the amount of cooling air delivered by the fan. From the diagram according to FIG. 2 it can be seen that that practically no air is conveyed up to the response temperature t. Depending on the speed of rotation of the fan itself bends when this response temperature t_ is overwritten, each individual fan

CL

sheet, creating a real promotion of cooling air up to

ORIGINAL INSPECTED

takes place at a maximum value. It can be seen from the diagram that in the response temperature range, that is from t to t depending on the speed η. Different air volumes are conveyed up to the speed n__ " will. In any case, however, when the response temperature is exceeded, the cooling air is promoted very quickly, with the final temperature t being reached correspondingly more quickly at lower speeds becomes, as with the maximum speed, at which even when the response temperature is slightly exceeded t uses appropriate funding.

Fig. 3 shows in a sectional view that it may be useful to make the fan blade 1 made of memory metal to add an educational pen that has been split up in this case. The parenting spring is in this case formed from three individual springs 5, 6 and 7, which are of different lengths and which all together are clamped with the fan blade 1 in the connecting web 2 to the fan hub.

The lengths of the individual springs 5, 6 and 7 are chosen so that an optimal curvature of the fan blade 1 is forced when the temperature rises. 25th

FIG. 4 shows a top view of the fan blade 1, the restraint in the area of the connecting web 2 can be seen.

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] FIG. 5 shows a further possible design of the counter spring 8. In this case, the counter spring is also divided into several parallel individual elements. In the embodiment shown in FIG The return spring is used to relieve bending stress in the memory metal Component of the fan lat.Loa, in the area of the Kinü Stress zu orruLchcin .-- This bending stress relief only applies to tensions insofar as they affect the reaction force on the return spring come from.

The invention has been explained with reference to some specific forms of management, it being for the on the It is apparent from those skilled in the art that a number of modifications are possible. In particular, the individual measures explained with reference to the various figures can also be combined with one another be combined. This means for example

ORIGiNAL INSPECTED

This relieves the bending stress

is enough that at a certain distance from the clamping [

point on the fan hub one perpendicular to the fan £

sheet tensioning with the help of the rivet 9 |

he follows. The rivet 9 is inserted so that the \

Individual elements of the counter spring as well as the fan blade 1 perform relative movements parallel to one another can, as these parts also form in this design firmly attached in the connecting web 2 must be in order to counteract the centrifugal forces occurring during operation.

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This means that in the embodiment according to FIG. 5, the individual leaves of the counter spring 8 can be designed to be of different lengths, with, for example, the lowermost only being able to extend into the area of the additional transverse recess 9. In any case, the essential advantage of a high response speed in the case of changing temperature conditions, such as can occur, for example, as a result of stationary load on the motor, is achieved. The low thermal response time constant is due to the intensive heat exchange on the fan blade surface as a result of forced convection. This intensive heat exchange enables a stable regulation of disturbance variables, such as load fluctuations on the engine, largely free of overshoots and periodic instability. The latter properties in particular could not be eliminated with the so-called Visco-LüfLers, a fan with a bimetal-controlled hydraulic coupling, which was widespread up to now. This is probably due to the fact that a bimetal, especially if it is not attached directly to the fan hub or to the fan blade itself, shows the cooler exhaust air temperature with too great a time delay and at the same time incorrectly depicts the amount, which is likely to be due to heat dissipation processes along the crankshaft, but also to the heat dissipation in the slip clutch cannot be ruled out.

Claims (1)

0 44 RP 22.8745 MAN MASCHINENFABRIK AUGSBURG-NÜRNBERG Aktiengesellschaft Nuremberg, November 22, 1980 Claims 1 J Device for the automatic temperature-dependent regulation of the cooling air volume conveyed by a fan, in particular the cooling air flow rate to a radiator of a motor vehicle or the like provided with a fan, whereby the angle of incidence of the fan blades is changed as a function of temperature in the sense of an increase and decrease of the air flow rate at a given speed characterized in that the fan blades (1) at least in the clamping area consist of a temperature-sensitive metal, possibly clad and / or sintered metal, if necessary made of metals of different expansion. 2. Apparatus according to claim 1, characterized by the use of a metal with temperature-controlled Shape memory, so-called memory metal. 3. Apparatus according to claim 1 or 2, characterized in that the fan blades (1) are reinforced by at least one spring element (5, 6, 7, 8) in the region of the temperature-controlled curvature. 4. Apparatus according to claim 3, characterized in that that the spring element (5, 6, 7, 8) is constructed from a sandwich-like composite of leaf springs. Device according to Claim 3 or 4, characterized by a spring assembly (5, 6, 7,) for optimization dos fan profile from a plurality of different long stacked leaf springs. Device according to claim 3 to 5, characterized in that that fan blade (1) and additional spring collar (8) except at the clamping point (3) are firmly but longitudinally displaceably connected to each other perpendicular to the longitudinal extension (9). 22.8745