WO2021037370A1

WO2021037370A1 - Liquid friction clutch

Info

Publication number: WO2021037370A1
Application number: PCT/EP2019/073145
Authority: WO
Inventors: Siddharth KUMAR; Kshitikesh Parmeshwar; Abhishek Gupta; Pranshu MISHRA; Murugesan AYYALUSAMY; Reshma GARUD; Tribhuvan RASYARA
Original assignee: Mahle International Gmbh; Mahle Anand Thermal Systems Private Limited
Priority date: 2019-08-29
Filing date: 2019-08-29
Publication date: 2021-03-04

Abstract

Liquid friction clutch (1), comprises a shaft (2) which is rotatable about an axis of rotation (R), a drive disk (3) arranged non-rotatably on the shaft (2) and a driven member (4) arranged rotatably on the shaft (2). The driven member (4) comprises a driven part (5) mounted rotatably on the shaft (2) and a cover (6) fixed on said driven part (5), wherein the drive disk (3) is accommodated axially between the driven part (5) and the cover (6). A radially extending annular transmission region (8) to receive a viscous fluid is formed between the drive disk (3) and the driven member (4), via which the drive disk (3) can be coupled to the driven member (4) to transmit a torque. The liquid friction clutch (1) comprises a storage chamber (10) for accommodating the viscous fluid which is formed in the cover (6) and which is separated axially from the drive disk (3) by a separating disk (11). The inlet path (12) is formed completely in the cover (6) and opens into a storage chamber (10) via an inlet opening (21). When the electromagnet (16) is switched off, the closure lever (17) is pivoted away from the inlet opening (21) and towards the separating disk (11) and thereby opens the inlet path (12). When the electromagnet (16) is switched on, the closure lever (17) is pivoted away from the separating disk (11) and towards the inlet opening (21) and thereby closes the inlet path (12).

Description

Liquid friction clutch

The invention relates to a liquid friction clutch, in particular for a motor vehicle fan, according to the preamble of claim 1.

In a liquid friction clutch for a motor vehicle fan, a drive disk is mounted firmly on a shaft driven by the internal combustion engine and a driven member is mounted rotatably with the motor vehicle fan. The shaft is thereby driven mechanically by the internal combustion engine and preferably is directly drive-connected to the crankshaft. Alternatively, the shaft can be driven via a belt drive. The torque is transmitted from the drive disk to the driven member and thereby to the motor vehicle fan via the viscous fluid - usually oil. In this case the viscous fluid is con veyed via an inlet path from a storage chamber into a transmission region be tween the drive disk and the driven member so that the drive disk and the driven member are frictionally coupled via the viscous fluid. If the driven member and thereby the motor vehicle fan should be decoupled from the drive disk, the fluid is conveyed back into the storage chamber via a return path from the transmission region. The storage chamber can be formed in the driven member and can be separated from the axially adjacent drive disk by a separating disk.

In order to regulate the inflow of the viscous fluid into the transmission region, the liquid friction clutch usually has a closure lever. The closure lever closes and opens the inlet path which leads via the separating disk from the fluid storage chamber in the driven member to the transmission region. The closure lever can, for example, be actuated electromagnetically. In addition, a magnetic armature is usually fixed on the closure lever, which cooperates with an external electromag net. The closure lever is then moved into the desired position by switching on and off the electromagnet. Such closure levers are known, for example, from DE 101 22795 A1 , DE 19742823 A1 and DE 101 31 402 A1. Alternatively, the closure lever can also be actuated in a temperature-dependent manner by a bi metal element, such as is described for example, in US 4405039 A.

In order to meet the safety requirements, the liquid friction clutch must remain switched on when the regulation fails. As a result, overheating due to failure of the motor vehicle fan can be prevented. This function can be implemented by an inlet path which is always open in the event of failure, which however requires complex technical solutions in the case of the electromagnetically actuated clo sure lever. Thus, for example, in DE 101 31 402 A1 a magnetic armature is also provided in addition to the electromagnet, the effect of which is amplified or at tenuated by the electromagnet. In DE 19742823 A1 an alternative solution with an axially displaceable closure lever is proposed which, however is complex in the same way. In DE 101 22795 A1 the closure lever can be opened by a return spring when the electromagnet is switched off.

The object of the invention is to provide an improved or at least alternative em bodiment for a liquid friction clutch of the generic type, in which the described disadvantages are overcome.

This object is solved according to the invention by the subject matter of the inde pendent claim 1. Advantageous embodiments are the subject matter of the de pendent claims.

A liquid friction clutch is provided for a motor vehicle fan and comprises a shaft which is rotatable about an axis of rotation, a drive disk arranged non-rotatably on the shaft and a driven member arranged rotatably on the shaft. The driven mem ber comprises a driven part mounted rotatably on the shaft and a cover fixed on said part, wherein the drive disk is accommodated axially between the driven part and the cover. A radially extending annular transmission region to receive a vis- cous fluid is formed between the drive disk and the driven member, via which the drive disk can be coupled to the driven member to transmit a torque. The liquid friction clutch comprises a storage chamber for accommodating the viscous fluid which is formed in the cover and which is separated axially from the drive disk by a separating disk. The storage chamber is fluidically connected to the transmis sion region via an inlet path and via a return path. The liquid friction clutch further comprises a magnet arrangement with an electromagnet and with a closure lever, which is pivotally mounted in the storage chamber at at least one fixed point. Ac cording to the invention, the inlet path is formed completely in the cover and opens into the storage chamber via an inlet opening. When the electromagnet is switched off, the closure lever is pivoted away from the inlet opening and towards the separating disk and thereby opens the inlet path. Furthermore when the elec tromagnet is switched on, the closure lever is pivoted away from the separating disk and towards the inlet opening and thereby closes the inlet path. As a result of the inlet path formed in the cover, the magnet arrangement can be implement ed simply compared to conventional solutions. In particular, additional compo nents are omitted and a safe and robust failure protection for the liquid friction clutch can be implemented.

Advantageously it can be provided that the liquid friction clutch comprises a sec ond inlet path with a second inlet opening. The second inlet opening passes through the separating disk and thereby fluidically and permanently connects the storage chamber to the transmission region via the separating disk. Expediently the second inlet opening has a much smaller diameter than the inlet opening. The second inlet opening can, for example, have a diameter between 1 mm and 2 mm. The second inlet opening helps to maintain minimum quantity of fluid re- tainment to minimize stalling affect. Advantageously the separating disk can be mounted non-rotatably on the cover, wherein the inlet opening in the cover and the second inlet opening in the separating disk are arranged radially opposite one another. Alternate way of positioning the separating disk could be an in-line posi tion with the inlet opening.

It can advantageously be provided that the closure lever comprises a clamping piece and a magnetic armature. In this case, the clamping piece is braced at the respective fixed point and as a result the closure lever abuts against the separat ing disk when the electromagnet is switched off. Here when the electromagnet is switched off, the return of the closure lever to the separating disk is achieved by the clamping force in the clamping piece. When the electromagnet is switched on, this then interacts with the magnetic armature so that the closure lever is pivoted away from the separating disk and towards the inlet opening. In this embodiment also, a region projecting towards the separating disk can also be provided on the clamping piece. Alternatively, the closure lever can comprise a clamping piece, a magnetic armature and a return spring, which acts against the magnetic force of the electromagnet and thereby moves the closure lever towards the separating disk when the electromagnet is switched off. Here when the electromagnet is switched off, the return of the closure lever towards the separating disk is achieved by the spring force of the return spring.

In an advantageous further development of the solution according to the invention it is provided that the cover has a ribbed structure facing away from the storage chamber with a plurality of ribs. The ribs diverge radially in this case and protrude axially from the cover. In addition, the respective ribs are adapted in their radial length and in their axial height in such a manner that a mass distribution of the cover about the axis of rotation is compensated. By this means the rotation of the driven member can be stabilized. By means of the ribbed structure, excess heat can advantageously be released towards the outside. In an advantageous embodiment of the inlet path, the inlet opening can open into the storage chamber via a dome-like projection of the cover and when the elec tromagnet is switched on, the closure lever can abut sealingly against the dome like projection and covering the inlet opening. In particular, an undesired leakage when the inlet path is closed can thereby be minimized. Advantageously the inlet path can be configured to be U-shaped and lead axially from the inlet opening into the cover, radially outwards inside the cover and axially to the transmission region inside the cover. Advantageously a seal can be arranged at the respective fixed point between the closure lever and the cover. The electromagnet can be fixed on the cover, facing away from the storage chamber.

Further important features and advantages of the invention are obtained from the subclaims, from the drawings and from the relevant description of the figures with reference to the drawings.

It is understood that the features mentioned previously and to be explained fur ther hereinafter can be used not only in the respectively given combination but also in other combinations or alone without departing from the scope of the pre sent invention.

Preferred exemplary embodiments of the invention are shown in the drawings and will be explained in detail in the following description, wherein the same ref erence numbers relate to the same or similar or functionally the same compo nents.

In the figures, in each case schematically:

Fig. 1 shows a sectional view of a liquid friction clutch according to the invention on an outlet path; Figs. 2 and 3 show sectional views of a liquid friction clutch according to the invention on an opened and closed inlet path;

Figs. 4 and 5 show views of a cover in a liquid friction clutch according to Figs. 2 and 3;

Fig. 6 shows a view of a separating disk in the liquid friction clutch ac cording to Figs. 2 and 3;

Fig. 7 shows a view of a separating disk arranged in the cover accord ing to Figs. 4 and 5.

Fig. 1 shows a sectional view of a liquid friction clutch 1 according to the inven tion. The liquid friction clutch 1 in this case comprises a shaft 2 which can rotate about an axis of rotation R, a drive disk 3 and a driven member 4. The drive disk 3 is in this case fixed non-rotatably on the shaft 2. The driven member 4 in this case comprises a driven part 5 and a cover 6 which are fixed on one another running around the shaft 2 and axially receive the drive disk 3. Located between the driven part 5 and the cover 6 is an annular seal 14 which seals the liquid fric tion clutch 1 towards the outside. The driven part 5 is in this case mounted rotat ably on the shaft 2 via a bearing 7 and the driven member 4 is thereby mechani cally rotationally decoupled from the drive disk 3 and the shaft 2. Between the drive disk 3 and the driven member 4 - in this exemplary embodiment the cover 6 - a transmission region 8 is formed which can receive the viscous fluid. The transmission region 8 is here formed by a groove profile 9a on the drive disk 3 and a groove profile 9b on the cover 6, which axially intermesh. The drive disk 3 can transmit the torque to the driven member 4 via the viscous fluid in the trans mission region 8 and is thereby fluidically rotationally coupled to the driven mem- ber 4. The coupling strength or the transmission ratio between the drive disk 3 and the driven member 4 can be influenced depending on the quantity of the vis cous fluid in the transmission region 8.

The liquid friction clutch 1 has a storage chamber 10 for the excess viscous fluid which is formed in the cover 6. The storage chamber 10 is separated axially from the drive disk 3 by a separating disk 11 which is fixed non-rotatably in the cover 6. The storage chamber 10 is fluidically connected to the transmission region 8 via an inlet path 12 and via a return path 13. Via the inlet path 12 the viscous fluid can flow from the storage chamber 10 into the transmission region 8 and via the return path 13 it can flow from the transmission region 8 back into the storage chamber 10. The inlet path 12 - here only partially visible - is formed according to the invention completely in the cover 6. In order to regulate the quantity of vis cous fluid in the transmission region 8, the liquid friction clutch 1 comprises a magnet arrangement 15 with a non-rotatable electromagnet 16 and with a closure lever 17. In this exemplary embodiment the closure lever 17 is pivotably mounted on the cover 6 at two fixed points 28 - only one visible here - inside the storage chamber 10. The closure lever 15 here comprises a magnetic armature 18 and a clamping piece 19 on which the magnetic armature 18 is fixed. The clamping piece 19 is in this case braced at the respective fixed point 28 in such a manner or configured in such a manner that when the electromagnet 16 is switched off - as shown here - the closure lever 17 is moved towards the separating disk 11 and abuts against this.

A motor vehicle fan 20 - not shown here - is fixed on the driven part 5 of the driv en member 4, which fan can be switched on or off by the liquid friction clutch 1. When the electromagnet 16 is switched on, this interacts with the magnetic arma ture 18 of the closure lever 17 so that the closure lever 17 is pivoted towards the inlet path 12 and away from the separating disk 11. The inlet path 12 is then closed by the closure lever 17. When the electromagnet 16 is switched off - as shown here - the closure lever 17 is pivoted from the inlet path 12 towards the separating disk 11 and the inlet path 12 is thereby opened. As a result, the liquid friction clutch 1 and accordingly the motor vehicle fan 20 are also switched on after a failure of the electromagnet 16 so that a safe and robust failure protection for the liquid friction clutch 1 is achieved. Furthermore the magnet arrangement 15 is simplified compared with conventional solutions.

Fig. 2 and Fig. 3 show sectional views of the liquid friction clutch 1 according to the invention. In Fig. 2 the electromagnet 16 is switched off and the inlet path12 is open. In Fig. 3 the electromagnet 16 is switched on - as indicated by the arrows - and the inlet path 12 is closed. As shown in Fig. 2 and Fig. 3, the inlet path 12 is U-shaped and formed completely in the cover 6. The inlet path12 in this case opens into the storage chamber 19 via an inlet opening 21 and into the transmis sion region 8 via an opening orifice 29. In inlet opening 21 is formed in a dome like projection 22 of the cover 6 so that when the electromagnet 16 is switched on, the closure lever 17 abuts against the dome-like projection 22 - as shown in Fig. 3 - sealingly and covering the inlet opening 21. In particular, an undesired leakage when the inlet path 12 is closed can thereby be minimized. Furthermore the liquid friction clutch 1 has a second inlet path 23 with a second inlet opening 24 which is formed in the separating disk 11. The second inlet opening 24 is in this case arranged radially opposite to the inlet opening 21 and remains perma nently open so that the storage chamber 10 is always partially fluidically connect ed to the transmission region 8. "Partially" means that the viscous fluid can flow from the storage chamber 10 into the transmission region 8 just via the always opened second inlet opening 24 and additionally via the opened inlet opening 21. Flowever, the second inlet opening 24 has a smaller diameter than the inlet open ing 21 so that the viscous fluid principally flows through the inlet path 12 into the transmission region 8. Also shown in Fig. 2 and Fig. 3 is the motor vehicle fan 20 which is fixed on the driven part 5 by means of screws 25.

Fig. 4 and Fig. 5 also show views of the cover 6 in the liquid friction clutch 1. In Fig. 4 the cover 6 is shown facing away from the separating disk 11 and the stor age chamber 10. The cover 6 has a ribbed structure 26 with a plurality of ribs 27 which diverge radially and project axially from the cover 6. Via the ribs 27 excess heat can be released from the cover 6 and from the viscous fluid to the outside. The ribs 27 are in this case adapted in their radial length and in their axial height in such a manner that a mass distribution of the cover 6 about the axis of rotation R is compensated. In Fig. 5 the cover 6 is shown facing the separating disk 11 and the storage chamber 10. Flere the groove profile 9b, the storage chamber 10 and the fixed points 28 at which the closure lever 17 is fixed are visible. At the fixed points 28 a seal can be arranged between the cover and the closure lever 17 in each case. The U-shaped inlet path 12 in this case leads from the inlet opening 21 to the opening orifice 29 and thereby fluidically connects the storage chamber 10 to the transmission region 8.

Fig. 6 shows a view of the separating disk 11 in the liquid friction clutch 1. Fig. 7 shows a view of the separating disk 11 which is arranged in the cover 6. The storage chamber 10 is in this case axially closed by the separating disk 11 and connected to the transmission region 8 via the inlet path 12 and the second inlet opening 24. The separating disk 11 is in this case mounted non-rotatably on the cover 6 for which the separating disk 11 has a fixing projection 30 and the cover 6 has a fixing recess 31. The fixing projection 30 in this case engages radially in the fixing recess 31 so that the separating disk 11 is always aligned relative to the cover 6.

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Claims

1. A liquid friction clutch (1 ), in particular for a motor vehicle fan (20),

- wherein the liquid friction clutch (1 ) comprises a shaft (2) which is rotatable about an axis of rotation (R), a drive disk (3) arranged non-rotatably on the shaft (2) and a driven member (4) arranged rotatably on the shaft (2),

- wherein the driven member (4) comprises a driven part (5) mounted rotatably on the shaft (2) and a cover (6) fixed on said driven part (5), wherein the drive disk (3) is accommodated axially between the driven part (5) and the cover (6),

- wherein a radially extending annular transmission region (8) to receive a vis cous fluid is formed between the drive disk (3) and the driven member (4), via which the drive disk (3) can be coupled to the driven member (4) to transmit a torque,

- wherein the liquid friction clutch (1) comprises a storage chamber (10) for ac commodating the viscous fluid which is formed in the cover (6) and which is separated axially from the drive disk (3) by a separating disk (11 ),

- wherein the storage chamber (10) is fluidically connected to the transmission region (8) via an inlet path (12) and via a return path (13),

- wherein the liquid friction clutch (1) comprises a magnet arrangement (15) with an electromagnet (16) and with a closure lever (17), which is pivotally mounted in the storage chamber (10) at at least one fixed point (28), characterized in

- that the inlet path (12) is formed completely in the cover (6) and opens into the storage chamber (10) via an inlet opening (21 ), - that when the electromagnet (16) is switched off, the closure lever (17) is piv oted away from the inlet opening (21 ) and towards the separating disk (11 ) and thereby opens the inlet path (12) and

- that when the electromagnet (16) is switched on, the closure lever (27) is piv oted away from the separating disk (11) and towards the inlet opening (21) and thereby closes the inlet path (12).

2. The liquid friction clutch according to claim 1, characterized in that the liquid friction clutch (1) comprises a second inlet path (23) with a second inlet opening (24) which passes through the separating disk (11) and thereby permanently fluidically connects the storage chamber (10) to the transmission region (8) via the separating disk (11 ).

3. The liquid friction clutch according to claim 2, characterized in that the second inlet opening (24) has a diameter between 1 mm and 2 mm.

4. The liquid friction clutch according to claim 2 or 3, characterized in that the separating disk (11) is mounted non-rotatably on the cover (6), wherein the inlet opening (21 ) in the cover (6) and the second inlet opening (24) in the separating disk (11) are arranged radially opposite one another.

5. The liquid friction clutch according to one of claims 1 to 4, characterized in

- that the closure lever (17) comprises a clamping piece (19) and a magnetic armature (18), wherein the clamping piece (19) is braced at the respective fixed point (28) and as a result the closure lever (17) abuts against the sepa rating disk (11) when the electromagnet (16) is switched off, or

- that the closure lever (17) comprises a clamping piece (19), a magnetic arma ture (18) and a return spring, wherein the return spring acts against the mag netic force of the electromagnet (16) and thereby moves the closure lever (17) towards the separating disk (11) when the electromagnet (16) is switched off.

6. The liquid friction clutch according to one of claims 1 to 5, characterized in that a seal is arranged at the respective fixed point (28) between the closure lever (17) and the cover (6).

7. The liquid friction clutch according to one of claims 1 to 6, characterized in that the electromagnet (16) is fixed on the cover (6) facing away from the storage chamber (10).

8. The liquid friction clutch according to one of claims 1 to 7, characterized in

- that the cover (6) has a ribbed structure (26) facing away from the storage chamber (10) with a plurality of ribs (27) which diverge radially and protrude axially from the cover (6) and

- that the respective ribs (27) are adapted in their radial length and in their axial height in such a manner that a mass distribution of the cover (6) about the axis of rotation (R) is compensated.

9. The liquid friction clutch according to one of claims 1 to 8, characterized in that the inlet path (12) is configured to be U-shaped and leads axially from the inlet opening (21) into the cover (6), radially outwards inside the cover (6) and axially to the transmission region (8) inside the cover (6).

10. The liquid friction clutch according to one of claims 1 to 9, characterized in that the inlet opening (12) opens into the storage chamber (10) via a dome-like projection (22) of the cover (6) and when the electromagnet (16) is switched off, the closure lever (17) abuts sealingly against the dome-like projection (22) and covering the inlet opening (21).

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