WO2014004338A1

WO2014004338A1 - Fluid friction clutch

Info

Publication number: WO2014004338A1
Application number: PCT/US2013/047238
Authority: WO
Inventors: Thomas Buchholz; Frank Gerber
Original assignee: BorgWarner Inc
Current assignee: BorgWarner Inc
Priority date: 2012-06-26
Filing date: 2013-06-24
Publication date: 2014-01-03
Anticipated expiration: 2014-12-26
Also published as: US20150144452A1; EP2679849A1; CN104508312B; CN104508312A; IN2015DN00415A; EP2679849B1; US9328780B2

Description

FLUID FRICTION CLUTCH DESCRIPTION The invention relates to a fluid friction clutch according to the preamble of claim 1.

Such a fluid friction clutch is known from EP 1 731 787 BL the disclosure of whic is hereby made ^'through, explicit reference to the disclosure of the present application.

The object of the present invention is to create a fluid friction clutch of the type specified in the preamble of claim 1, which affords a simple way of increasing the clutch efficiency.

This object is achieved by the features of claim 1.

The provision of a rotaiably supported supply pump element, which defines a shear gap with the housing, is a. simple way, using a differential speed between the pump element and the housing or the secondary side of the fluid friction clutch, of producing a volumetric flow from the storage chamber into the working chamber thai varies as a function of the differential speed.

One of the particular advantages of the fluid friction clutch according to the invention firstly lies in the fact that only a small quantity of clutch fluid is required, since, owing to the arrangement previously explained, an active feed pump is formed in the oil reservoir, which is advantageous with, regard to the quantity of clutch fluid compared^' to the known reliance on centrifugal forces for filling the working chamber.

The fluid friction clutch according to the invention moreover has a faster response characteristic due to the smaller proportion of clutch fluid.

Furthermore, an extremely compact construction results, since the outside diameter of the storage chamber or the reservoir can be made larger than the inside diameter of the workin chamber.

To sum up, therefore, it can be established that, an outstanding clutch performance can be achieved owing to the fact that the supply pump element rotates at primary speed (speed of the shaft.) and skims off clutch fluid opposite the housing.

The dependent claims contain advantageous developments of the invention The clutch performance can be further improved by providing a return pump, which rotates at secondary or primary speed and skims off clutch fluid owing to its arrangement between the clutch disk and the housing.

Fmther details, advantages and features of the present, invention are set forth in the following description of exemplary embodiments, ^'referring to the drawing, in which: figure 1A shows a sectional representation of a fluid friction clutch according to the invention viewed from a first direction, figure IB shows a perspective, sectional representation of the fluid friction clutch according to figure I A, figure 2A shows a representation of the fluid friction clutch corresponding to figure l A viewed from a second direction. figure 2B shows a representation of the fluid friction clutch corresponding to figure

IB viewed from the direction according to figure 2 A, figure 3 shows a perspective top view of the fluid friction clutch without housing cover, figure 4 shows a partial representation of the fluid friction clutch corresponding to figure 3, figure 5 shows a partial representation of another area of the fluid friction clutch

corresponding to figure 4, figure 6 shows a detailed presentation of a va l ve element, represented in figure 5, figure 7 shows a first embodiment of a hydraulic circuit diagram for the fluid friction clutch according to the invention, and figure 8 shows a representation, corresponding to figure 3, of a second embodiment of the hydraulic circuit diagr am for the fluid friction clutch according to the invention. Figure 1A shows a sectional representation of a fluid friction clutch 1 according to the invention, which comprises a housing, which is usually assembled from a housing body 2 and a cover 3.

A clutch disk 4, which is rotatable relative to the housing 2, 3, is arranged in the housing 2, 3. The clutch disk 4, rotatable relative to the housing 2, 3, is here arranged, rotafionally fixed, at one end 5 of a shaft 6 centrally supported inside tlie housing 2, 3. A drivable operative element 7, represented in slightly simplified schematic form, which may be embodied as a fan wheel, for example, is fixed to the housing 2, 3.

A working chamber 9, which, as can be seen from figure. 1A, comprises working gaps 15, which allow a transmission of the torque owing to a shear action on the clutch fluid fed to the working chamber 9, is arranged between the housing 2, 3 and the clutch disk 4.

A storage chamber 10 is provided for said clutch fluid, a feed duct lla, lib leading from the storage chamber 10 to the working chamber 9 and thereby forming the supply feed.

According to the invention, a return pumping system or a return pump 16 is furthermore provided, which serves for returning the clutch fluid from the working chamber 9 to the storage chamber 10. This return pump is formed either by the resulting centrifugal-force, which pmnps out fluid to the storage chamber 10 in order to evacuate the working chamber 9, or alternatively by the possible provision of a separate component in the form of an active return pump, as is indicated schematically in the hydraulics diagram in figures 7 and 8. which acts through shearing force.

The fluid friction clutc 1 fiirther comprises a stationary clutch part 13, which is rotatable relative to the housing 2, 3 and is preferably embodied as a magnet, in particular a solenoid.

As is apparent from the representation in figures 1 A, IB, 2A a d 2B and 4, an internal reservoir 18 is furthermore provided, which is connected to the storage chamber 10 by way of the feed duct 11. Here the valve 17 is inserted into the feed duc t 11a, l ib and (he storage chamber 10 is arranged outside, as can be seen in detail from figures 1 A to 2B.

A return flow barrier 1 is frirtherniore provided, which is arranged between the valve 17 and the reservoir IS. This return flow barrier 19 may be. a small tube, for example, which pro jects above the fluid level into the reservoir 18.

As can also be seen from figures 1 A to 2B and 4 and 5, a return valve 20 is also provided, which is operatively connected ^'to the valve 17 and opens or closes a return, duct 23 to the storage chamber 10.

The valve 17, preferably embodied as a multiway valve, comprises a valve element 24, which has a passage 25 and a fluid inlet recess 26 for mtroducing fluid into the working- chamber 9, which can be seen in particular from figure 5 and the detailed representation in figure 6.

An actuator 27 is mrtherrnpre provided for actuating the valve 17 and the return valve 20. The actuator 27 preferably comprises an armature 28, rotatable relative to the shaft 26, and a flux ring 29, which is rotatable with the shaft 6 and which can be excited by the stationary clutch part in the form of the magnet 13 (see figure 3).

The actuator 27 may also be moved by a bimeta strip (not shown) instead of the armature and the magnet.

In an especially preferred embodiment, the storage chamber 10 is provided on the secondary side of the fluid friction clutch 1 and the internal chamber 18 on the primary side of the fluid friction clutch 1.

Finally, in an alternative embodiment according to figure 7, the fluid friction clutch I comprises a return bore 30 for the purpose of pressure relief which connects the feed duct or the feed duct portion 1 la to the storage chamber 10 by way of a further fluid inlet aperture (not shown) of the valve 17. hi this embodiment, no internal volume is provided, so that the oil is not returned by way of the internal reservoir. This embodiment of the fluid friction clutch 1 according to the invention -may be used in clutches of smaller design, which do not need an internal volume, since in these the drag torques are low.

In addition to the written disclosure of the invention above, explicit reference is hereby made to the graphic representa tion of the in vention hi figures 1 to 4, intended to supplement the disclosure of the invention. List of reference numerals

1 fluid friction clutch

2, 3 housing (2: housing body, 3; cover)

4 clutch disk

5 end of the shaft 6

6 shaft

1 operative element (e.g. pump iin

8 second end of the shaft 6

9 working chamber

10 storage chamber

Ua, l ib feed duct

1 T Micdi gap

13 stationary ckitch parts (magnet)

14 supply pump element

15 working gaps

16 return pump

17 valve

18 internal reservoir

19 return flow barrier

20 return valve

J \ valve arm

22 connecting bore

23 reiimi duct

24 valve element

25 passage

26 fluid inlet, recess

27 actuator

28 armature

29 flux ring

30 return bore

Claims

1. A fluid .friction clutch ( 1)

- having a housing (2, 3)

- having a clutch disk (4),

• which is rotatable relat ive to the housing (2, 3). and

• which is arranged at one end (5) of a shaft (6) centrally supported inside^' the housing (2. 3),

- having a working chamber (9) between the housing (2. 3) and the clutch disk

(4);

- having a storage chamber (10) for clutch fluid; and

- having a feed duct (11a, l ib), which leads from the storage chamber (10) to the working chamber ( 9 ). characterized

- by a supply pump element (14) which is rotatable relative to the housing (2, 3) and

• which is arranged, rotationally fixed, on the shaft (6), and

• which defines a shear ga (12) with the housing (2, 3); and

- by a valve (17), which is arranged in the feed duct (I la, l ib), and characterized in

- that an operative element (7) is arranged on the housing (2, 3).

2. The fluid fiiction clutch as claimed in claim 1, characterized hi that a stationary clutch part (13) is provided, relative to wliich the housing (3) is rotatable.

3. The fluid friction clutch as claimed in claim 1 or 2, characterized by an internal reservoir (18), which is connected to the storage chamber (10) by way of the feed duct (1 1 , 1 lb) with insertion of the valve (17).

4. The fluid friction clutch as claimed in claim 3, characterized by a return flow barrier (19), wliich is arranged between the valve (17) and the reservoir (18).

5. The fluid friction clutch as claimed in one of claims 1 to 4, characterized in that the valve (17) is a multiway valve.

6. The fluid friction clutch as claimed in one of claims 1 to 5, characterized by a return valve (20), which is operatively connected to the valve (17) and which opens and closes a return duct (23) to the storage chamber (10).

7. The fluid friction clutch as claimed hi claim 5, characterized in that the muttiway valve (1:7) comprises a valve element (24), which as a passage (25) and a fluid inlet recess (26) for introducing fluid into the working chamber (9).

8. The fluid friction clutch as claimed in one of claims 1 to 7, characterized by a return pump (16) for returning clutch fluid from the working chamber (9) to the storage chamber (10).

9. The fluid friction clutch as claimed in one of claims 1 to 8, characterized by an actuator (27) for actuating the valve (1.7) and the return valve (20).

10. The fluid friction clutch as claimed in claim 9, characterized in that the actuator (27) comprises an armature (28), rotaiable relative to the shaft (6), and a flux ring (29), which is rotaiable with the shaft (6) and which is excited by the stationary clutch part (13).

11. The fluid friction clutch as claimed in claim 9, characterized in that the actuator (27) can be moved by means of a bimetal strip arrangement.

12. The fluid .friction clutch as claimed in one of claims 1 to 11, characterized in that the storage chamber (10) is preferably arranged on the secondary side.

13. The fluid friction clutch as claimed in one of claims 1 to 12, characterized in that the internal reservoir (18) is arranged on the primary side.

14. The fluid friction clutch as claimed in claim 1, characterized by a return bore (30) for the purpose of pressure relief, which connects a feed duct portion (1 la) of the feed duct (I la, ί lb) to the storage chamber (10) by way of a further fluid inlet aperture of the valve (17).