EP0634568B1 - Friction clutch especially for motor vehicle engine fan - Google Patents

Description

The invention relates in particular to a friction clutch for a fan wheel of a motor vehicle internal combustion engine or the like according to the preamble of claim 1.

State of the art:

DE 32 03 143 C2 is a friction disc clutch for the Fan wheel of a fan in particular Motor vehicle internal combustion engines became known at which the fan wheel with the friction disc clutch switched off by an eddy current coupling Coupling device is towed. Here is the Drive shaft with a rotor and the free-running Fan wheel with a permanent magnet of the eddy current clutch connected. Task and aim of the known It is the friction disc clutch, the fan wheel   the motor vehicle engine even when switched off Friction disc clutch via an eddy current clutch with a certain minimum towing speed to move for example the cooling of those located in the engine compartment to ensure electronic components. To one The fan wheel can cover increased cooling requirements of the fan in the known device via a Electromagnetically actuated friction disc clutch on the immediate speed of the drive shaft, d. H. on the Engine speed are driven. Such a state is however only when the engine is subjected to the highest loads required. Otherwise, when switched off electromagnetic friction disc clutch a diminished Fan speed can be set, which is characterized by the maximum drag speed of the eddy current clutch determined. For example, this towing speed is the known one Arrangement in the order of approx. 1100 rpm. she will by the number of permanent magnets and by the Distance between rotor and permanent magnet regulated. The known device can therefore two fan speeds generate by the towing speed of the Eddy current clutch and the engine speed itself determined are.

A corresponding device with two electromagnetic actuatable clutch units is from DE 34 43 523 A1 known.

From an even older utility model DE-U-81 09 726 a fan arrangement has become known in which none Eddy current clutch for generating a towing speed of the Fan wheel is used so that the fan wheel after the Switch on an electromagnetic friction disc clutch is driven with the engine speed. When switched off The friction disc clutch can at most over the Ball bearing friction of the fan wheel hub thus mounted   be dragged along.

Finally, the applicant's EP 0 317 703 B1 Electromagnetically actuated friction clutch assembly for driving a fan wheel of a fan on one Motor vehicle internal combustion engine became known, in which for Manufacturing the engine speed a first electromagnetic Friction disc clutch is provided which the fan wheel drives again in a ratio of 1: 1 to the engine speed. A lower towing speed is indicated by a Eddy current clutch generated by a second electromagnetic friction clutch is switched on the first electromagnetic friction clutch remains off. Are both electromagnetic Clutches turned off, so the runner becomes the Eddy current coupling via the drive shaft and the Ball bearing friction still moves, so that there is still one further reduced drag speed.

The use of electromagnetically actuated Friction disc clutches for the fan drive are therefore in various configurations have become known. Work with it such friction disc clutches purely frictional, so that in Contrary to form-fitting couplings the power to Indent must act as long as the clutch is transmitting power should. As an engagement force and thus as a clutch force consequently mainly used magnetic traction. This can be disadvantageous in special applications, because additional current management measures with appropriate Storage of the stator for the electromagnetic clutch required are.

Furthermore, through DE-A-2815474, WO-A-91/11594 and US-A-4425993 coupling devices are known become by means of a pneumatic Piston cylinder unit are operated. Here presses   Drive piston on a friction disc attached to a Counter disc is pressed. The adhesion is here thus between the friction disc and the counter disc produced.

Advantages of the invention:

Compared to these known devices according to the present invention an alternative embodiment can be found, in particular on the use of Electromagnetic disc clutches waived. The advantages of one should be as possible Versatility of the friction clutch for one Fan drive are retained, with the input shown criteria are decisive. On the corresponding statements in the specified publications is hereby expressly referred to.  

The friction disc clutch according to the invention for the drive A fan wheel unfolds its full advantages with large ones Bus engines or truck engines that are turbocharged Motors are trained. The charge air of a turbocharger must are usually cooled on the radiator of the motor vehicle, to bring them to an optimal working temperature. Furthermore, such vehicles work with a so-called Retarder brake that brakes the vehicle via a Oil circuit, a so-called Vöttinger clutch accomplish. This is the one that occurs when braking Energy is used to move an oil stream, which is Oil in turn can heat up considerably. This oil also has to go through that Fan system can be cooled in an oil cooler. Finally the water cooler of the internal combustion engine must also be cooled be what about the fan drive of the fan he follows.

The above remarks show that the cooling system of such Motors works very sensitively and high Subject to stress. Is the cooling of the individual Units are not optimally designed, so the motor works with deteriorated efficiency, which in particular also affects affects fuel consumption and exhaust emissions. It must be ensured that the internal combustion engine too does not run undercooled, because this also makes it bad Combustion of the fuel is connected.

To meet these requirements, one is highly sensitive switchable friction clutch required on the individual operating states can be adjusted. Here   weight should be avoided as much as possible, with existing Units to be used in the motor vehicle.

The friction clutch according to the invention should therefore in such a system of aggregates will be integrated, whereby the already existing compressed air circuit for Air brakes of the motor vehicle or an oil circuit to the extent that a corresponding one is hereby used The friction clutch can be connected. As a result it is provided according to the invention that, for example, a air-operated piston / cylinder device one Friction disc clutch actuated or overrides that an immediate application of the fan wheel with the Engine speed should make. When open Friction disc clutch should be an additional existing Eddy current coupling in a manner known per se Required lower drag speed of the fan wheel cause. It is generally sufficient that the Eddy current coupling directly with the drive shaft of the Friction clutch is connected so that the fan wheel driven at least with the associated towing speed becomes. Of course there can be another one too Intermediate clutch to be turned on, the Eddy current clutch only used when needed.

Furthermore, according to the invention, one over the drive piston axially displaceable armature disk provided with a The friction disc lining of the friction disc clutch interacts. It is therefore also possible to create a positive connection between the armature disk and the friction disk lining to manufacture.

The actuation of the friction disc clutch via a pneumatic or hydraulically acting piston / cylinder arrangement alternatively take place in such a way that either with appropriate Pressurization opened the friction disc clutch or   closed is. The former causes one Safety device, since no pressure is applied the friction disc clutch is closed and thus that Fan wheel at motor speed, d. H. at maximum speed is driven. Accordingly, the pneumatics or hydraulics fall off, the fan wheel works at maximum speed. Conversely, the pneumatic or hydraulic   Piston / cylinder drive for the friction disc clutch such are switched that this only with one Pressurization of the piston / cylinder device activated is, so that only in this case a full speed drive of the fan wheel.

Further details and advantages of the invention emerge from the drawings and are from the following Explanation of exemplary embodiments can be found.

Fig. 1

ein erstes Ausführungsbeispiel für eine Reibschaltkupplung mit Schaltung der Reibscheibenkupplung bei Druckentlastung der Kolben/Zylindereinheit und

Fig. 2

eine alternative Ausführungsform mit der Schaltung der Reibscheibenkupplung bei druckbelasteter Kolben/Zylindereinheit.

Show it

Fig. 1

a first embodiment for a friction clutch with switching the friction disc clutch with pressure relief of the piston / cylinder unit and

Fig. 2

an alternative embodiment with the circuit of the friction disc clutch with a pressure-loaded piston / cylinder unit.

Description of the invention:

The friction clutch 1 shown in FIG. 1 is used for Drive of a fan wheel 2 and thus as a cooling unit especially for a motor vehicle internal combustion engine. The shown friction clutch is a so-called Two-stage clutch trained, as in the DE 32 03 143 C2 of the applicant is described. On the The content of this publication is hereby expressly referred to taken. For direct coupling of the rotating Fan wheel 2 to the speed of a drive shaft 4 is one first friction disc clutch 5 is provided, the pneumatic or is hydraulically actuated. Is this first Friction disc clutch switched on, so there is a   non-positive connection between the drive shaft 4 and the fan wheel 2 to be driven in a ratio of 1: 1.

If this first friction disc clutch 5 is switched off, the fan wheel 2 is nevertheless driven via the eddy current clutch 6, which is still present, at a reduced towing speed, the towing speed depending on the distance s ₁ between the impeller 7 and the permanent magnets 8. Depending on the application, this distance is selected between 0.5 and 4 mm, with towing speeds being set, for example, in the order of magnitude up to approximately 1100 rpm. The number of permanent magnets also determines the size of the towing speed.

1, the drive shaft 4 the friction clutch 1 via a cup-shaped housing 9 driven, a key 10 a positive Connection to the drive shaft 4 and a connecting flange 11 Connection to the crankshaft of a not shown Automotive internal combustion engine forms. To this housing 9 is over a screw 12 in turn a cross section Z-shaped housing 13 screwed, which for receiving the Rotor 7 of the eddy current clutch 6 is used. Through this Arrangement, the friction disc clutch 5 is annular from the Eddy current clutch 6 enclosed. The eddy current clutch 6 consists of a face wheel with its rotor Copper disc 14 and a downstream steel disc 15, which by means of a screw connection 16 on the annular Rotor 7 are attached.

Opposed to the rotor wheel 7 of the eddy current clutch 6 with a gap s ₁ is a magnetic disk wheel 17, in which the permanent magnets 8 are embedded on the circumference of the annular disk. The number of magnets is determined by the respective application and determines the size of the towing speed.

The magnetic disk wheel 17 has a cross section again Z-shaped or cup-shaped clutch housing 18 connected, which is to accommodate the first Friction disc clutch 5 is used. The pot-shaped Coupling housing 18 is radial Mounting flange 19 via a screw 20 with the Magnetic disk wheel 17 connected. Another Screw connection 21 connects this radial Mounting flange 19 of the cup-shaped clutch housing 18th with a mounting housing 22 flanged on the end face for the fan wheel 2 via a screw connection 23. This Fan wheel mounting housing 22 is approximately in cross section L-shaped with a radial wall section 24 and an axial, pot-shaped wall section 25 which extends towards the front. The Fan wheel mounting housing 22 also has one 1 axially extending in the direction Internal combustion engine housing section 26, the performs several functions. The mounting housing 22 is via the axial housing section 26 on the drive shaft 4 via a double ball bearing 27 rotatably mounted. At the same time forms the radial wall section 24 with the axial Housing section 26 has an annular recess 28 with a cylinder chamber 29 for receiving a pneumatic piston 30 connected is. The annular pneumatic piston 30 of the The friction disc clutch 5 is in the cup-shaped housing 18 its cylindrical outer surface 31 mounted. The inner one Bearing surface 32 of the annular piston 30 is supported the axial housing surface of the housing section 26. Of the annular piston 30 is U-shaped in cross section formed, the radially outer leg 33 approximately has twice the length as the radially inner Leg 34. The piston 30 is at its radial End face 35 is pressurized with compressed air Fastening housing 22 via a compressed air supply bore 36 is fed. For this is the axial and cup-shaped   Wall section 25 of the mounting housing 22 with a Rotary coupling 37 for the air supply to the interior 38 of the Wall section 25 provided.

The friction disc clutch 5 can be actuated pneumatically Coupling trained. For this is in the Clutch housing 18 an axially displaceable armature plate 39, which by means of an annular spring washer 40 without torsional play Housing 18 is attached. The ring spring washer 40 instructs on its surface several mounting holes that alternately for fastening the adjacent components to serve. The screw connection 57 serves this purpose Spring assembly 41 presses the radially outer area of the Armature disk 39 against the radial end face 42 of the axially extending outer leg 33 of the pressure piston 30.

Opposing the armature disk 39 is a counter disk 43 arranged, which is connected via a screw 44 to the Fastening housing 22 is connected. The serves axially extending housing section 26 of the Fastening housing 22 as a spacer and as a housing section for receiving the pressure piston 30.

Between the counter plate 43 and the armature plate 39 is a Arranged friction disc lining 45, which has a flexible, axially displaceable disk 46 by means of the Screw connection 47 is connected to the drive shaft 4.

The friction clutch according to FIG. 1 works as follows:

Is the pressure space 28, 29 located in front of the piston surface 35 via line 36 with pressure medium, e.g. B. compressed air acts, the piston 30 in the clutch housing 18th and in the housing section 26 axially in Fig. 1 to the right moves and presses with its radially outer   Leg 33 against the armature plate 39 against the force of Spring assembly 41. The flexible ring spring washer 40 enables the axial movement. This makes the non-positive Connection of the friction disc clutch 5 released so that the Friction plate lining 45 freely between the armature plate 39 and the counter disk 43 can rotate on the drive shaft 4. In In this case, only the eddy current clutch 6 is effective the engine speed of the motor vehicle engine via the connecting flange 11 on the pot-shaped housing 9 and from there on the Z-shaped Housing 13 transmits. The flanged to the housing 13 Eddy current clutch 6 causes a reduced Speed transmission to the radial mounting flange 19 of the clutch housing 18 and from there to Fastening housing 22 to which the fan wheel 2 is fastened is. Despite the high engine speed, the fan blade is accordingly of the fan 3 with a reduced towing speed driven.

Is an immediate speed ratio of the engine speed on the fan wheel 2, the pressure piston 30 is on relieves its end face 35 with pressure medium, so that this exerts no pressure on the armature plate 39. In In this case, the spring assembly 41 presses the armature disk 39 against the friction disc lining 45 and this against the Counter washer 43, so that a positive connection between the drive shaft 4 rotating at engine speed and the clutch pack, consisting of armature plate 39 with Ring spring washer 40, friction washer lining 45 and counter washer 43 consists. This torque is via the fixed connection of the Armature plate 39 to the clutch housing 18 and Fastening housing 22 on the one hand or by the Counter washer 43 via the screw connection 44 for Fastening housing 22 on the other hand on the fan wheel 2 and thus transferred to the fan 3.

The selected arrangement according to Fig. 1 has the advantage that at   failing compressed air supply in the system the higher Fan speed by forcing the Friction disc clutch 5 is formed. In case of doubt, therefore the higher cooling effect of the fan in this Circuit arrangement effective.

2 is a modified one Circuit arrangement of the friction disc clutch 5 selected. in the the rest are the same or corresponding parts with the same Reference numerals as designated in Fig. 1.

The motor vehicle engine, not shown, is driven via a pulley 48 on the drive shaft 4 of the friction clutch 1. Of course, there can also be a direct connection of the drive shaft 4 to the crankshaft of the drive motor. Via the feather key 10, the drive shaft 4 is positively connected to a receiving housing 13 for the eddy current clutch 6. This receiving housing has an axial wall section 49, a funnel-shaped wall section 50 and a radially extending wall section 51. The radial wall section 51 carries on its left end face the magnetic disk wheel 17 for receiving the permanent magnets 8 of the eddy current clutch 6. The rotor 7 of the eddy current clutch, formed from the copper disk 14 and the steel disk 15, is opposite with a gap s ₁ .

The rotor 7 of the eddy current clutch 6 is in the Fan wheel mounting housing 22 embedded on the front and firmly connected to it. Via a screw connection 23 the impeller 2 attached to the mounting housing 22. The Impeller mounting housing 22 is on the drive shaft 4 via the ball bearing 27 freely rotatable, the Ball bearing 27 on the axial wall portion 49 of the Housing 13 is arranged.  

The clutch housing 18 for receiving the piston 30 of the Friction disc clutch 5 has an annular circumferential Cylinder chamber 52 in which the annular piston 30 is axially displaceable. The one behind the piston 30 lying cylinder space 29 serves to pressurize the end face piston surface 35 with a pneumatic or hydraulic pressure medium, which has a radial extending supply bore 36 supplied to the cylinder chamber 29 becomes. A rotary coupling 37 in turn serves to feed the Pressure medium to the cylinder chamber 29.

The clutch housing 18 is with its radially outer axial wall section 53 via the screw connection 21 with the fan wheel mounting housing 22 rotatably connected.

The friction disk clutch 5 is formed by the armature disk 39, which in turn is fastened to the clutch housing 18 in an axially displaceable manner via a spring disk 54 and a screw connection 55, 57. The armature disk 39 and the piston 30 form an axially displaceable structural unit which is held by the ring spring washer 54. The armature disk 39 interacts with the rear surface 56 of the radial wall section 51 of the housing 13, which lies opposite the armature disk 39 with a gap s ₂ . The rear end face 56 and the armature disk 39 are designed as friction disk linings. When the cylinder chamber 29 is pressurized, the piston 30 presses the armature disk 39 against the rear end face 56 of the wall section 51 while overcoming the gap s ₂ .

2 works accordingly follows:

The pressure chamber 29 of the cylinder chamber 52 is not included Pressure medium loaded, so the friction disc clutch 5 is not   active. In this case, the pulley 48 opens the drive shaft 4 transmitted engine speed via the Key 10 on the housing 13 and thus on the Transfer eddy current clutch 6. The eddy current clutch 6 transfers a reduced speed to the Fan wheel mounting housing 22 and thus on that Fan wheel 2. The size of the towing speed is determined by the Structure of the eddy current clutch 6 determined.

An immediate speed transmission from the pulley 48 to the fan wheel 2 takes place by actuating the friction disc clutch 5. For this purpose, the pressure chamber 29 is loaded with pressure medium, in particular with compressed air, so that the piston 30 overcomes the armature disk 39 while overcoming the gap s ₂ against the rear surface 56 of the radial wall section 51 of the housing 13 presses. In this case, the frictional connection from the drive shaft 4 via the housing 13 to the armature disk 39 and from there via the ring spring washer 54 to the clutch housing 18. The torque is further transmitted via the radially outer, axial wall section 53 and the screw connection 21 to the fan wheel -Fastening housing 22 and thus on the fan wheel 2.

The embodiment according to FIG. 2 accordingly includes one Compressed air circuit, the one when the compressed air acts direct coupling of the motor speed to the fan wheel causes.

Claims (10)

1. Friction clutch for a fan wheel of a motor vehicle internal combustion engine or the like, the fan wheel (2) being directly connected to a drive shaft (4) or the like for the direct transmission of the engine rotational speed by means of a first friction disc clutch (5) and the fan wheel (2) being entrained by a second clutch appliance (6), configured as an eddy-current clutch, when the friction disc clutch (5) is disengaged, characterized in that the friction disc clutch (5) is configured as a pneumatically or hydraulically actuated clutch (5) with a piston/cylinder unit for the direct drive of the fan wheel (2), which piston/cylinder unit can be subjected to pressure medium by means of a rotary joint (37) and that the drive piston (30) actuates an anchor plate (39), which can be axially displaced by means of a flexible annular spring plate (40, 54) and which interacts with a friction disc lining (45) of the friction disc clutch (5).
2. Clutch according to Claim 1, characterized in that the drive shaft (4) of the friction clutch (1) is connected directly to the eddy-current clutch (6) by means of a drive housing (13), the eddy-current clutch (6) being connected at the output end to a fan wheel fastening housing (22) for fastening the fan wheel (2) and the fan wheel fastening housing (22) being decoupled with respect to rotational speed from the drive shaft (4) by means of a ball bearing (27).
3. Clutch according to Claim 2, characterized in that the fan wheel fastening housing (22) is directly connected to a friction disc clutch accommodation housing (18) which has a cylinder space (29, 52) for accommodating a drive piston (30) of the piston/cylinder unit and in that the axially displaceable drive piston (30) actuates the friction disc clutch (5) in the sense of subjecting the friction disc clutch (5) to pressure or relieving it and, by this means, of directly connecting the drive shaft (4) to the fan wheel (2) or decoupling the drive shaft (4) from the fan wheel (2).
4. Clutch according to claim 3, characterized in that the drive shaft (4) is connected to an axially displaceable flexible clutch plate (46) which carries a friction disc lining (45) on both sides and in that when the drive piston (30) is not subjected to pressures the clutch plate (46) is frictionally clamped between the anchor plate (39) connected to the clutch housing (18) and a counterplate (43) firmly connected to the fan wheel fastening housing (22).
5. Clutch according to one or more of the preceding claims, characterized in that the anchor plate (39) can be pressed axially against the friction disc lining (45) of the friction disc clutch (5) by a plate spring (41).
6. Clutch according to one or more of the preceding claims 1-3, characterized in that when subjected to pressure, the drive piston (30) closes the friction disc clutch (5) in the sense of a clutch actuation and therefore of a direct rotational speed transmission.
7. Clutch according to one or more of the preceding claims, characterized in that the housing connected to the drive shaft (4) acts simultaneously as a counterplate (43) of the friction disc clutch (5) for the drive-end fastening of the eddy-current clutch (6) by means of its radial wall section (51), which counterplate (43) interacts with the anchor plate (39) when the drive piston (30) is subjected to a force.
8. Clutch according to Claim 7, characterized in that the anchor plate (39) is supported by means of a flexible annular spring plate (40, 54) so that it can be axially displaced in the clutch housing (18).
9. Clutch according to one or more of the preceding claims, characterized in that the anchor plate (39) and the piston (30) form a constructional, axially displaceable unit and enclose between them the flexible annular spring plate (54).
10. Clutch according to one or more of the preceding claims, characterized in that the drive piston (30) is subsjected to pressure by means of a rotary joint (37), on the rotatable connection housing (25, 18), leading to the pressure space (29) of the piston/cylinder unit.