A torsion damping apparatus between the crankshaft of the engine and the input shaft of the change-speed transmission of a motor vehicle has two flywheels one of which is driven by the crankshaft and the other of which drives the input shaft by way of a friction clutch which generates heat. In order to prevent the transfer of heat from the friction clutch to the antifriction bearing between the flywheels, which are rotatable relative to each other against the opposition of a damper, the bearing is at least partially surrounded by a thermal barrier of synthetic plastic, ceramic or metallic material which prolongs the useful life of the bearing and enhances the torsion damping action of the damper. The thermal barrier can constitute or form part of the damper. The bearing can be disposed radially inwardly of the location of engagement between the clutch and the other flywheel and can be cooled by streams of air flowing through an annulus of passages each having a first end disposed radially inwardly of the friction surface of the other flywheel and a larger second end in a second surface of the other flywheel opposite the friction surface. Heat barriers in the other flywheel can alternate with the passages in the circumferential direction of the other flywheel.
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0. 9. Apparatus for compensating for variations of torque, especially for fluctuations of torque which is transmitted between a combustion engine and an input means of a transmission, comprising a first and a second flywheel, said flywheels being rotatable relative to each other, said first flywheel being connectable with the engine and said second flywheel being connectable with the input means of the transmission; a friction clutch carried by one of said flywheels; antifriction bearing means between said flywheels; damper means arranged to oppose rotation of said flywheels relative to each other and including series-connected first and second dampers, at least one of said dampers having energy storing means acting in the circumferential direction of said flywheels; and a disc non-rotatably connected with said one flywheel to maintain said bearing means in a predetermined axial position relative to said one flywheel, said disc having means for stressing said energy storing means.
0. 20. Apparatus for compensating for variations of torque, especially for fluctuations of torque which is transmitted between a combustion engine and an input means of a transmission, comprising at least two flywheels including a first and a second flywheel, said flywheels being rotatable relative to each other, said first flywheel being connectable with the engine and said second flywheel being connectable with the input means of the transmission; a friction clutch carried by one of said flywheels; damper means arranged to oppose rotation of said flywheels relative to each other and comprising energy storing elements acting in the circumferential direction of said flywheels; an antifriction bearing between said flywheels; a thermal insulator having means for at least reducing the transfer of heat between said bearing and said one flywheel; and a disc nonrotatably connected with said one flywheel to axially secure said bearing on said one flywheel, said disc having means for stressing said energy storing elements.
1. Apparatus for compensating for variations of torque, especially for fluctuations of torque which is transmitted between a combustion engine and an input means of a transmission, comprising at least two flywheels which are rotatable relative to each other, one of which is connectable with the engine and the other of which is connectable with the input means of the transmission and carries a disengageable friction clutch; antifriction bearing means interposed between said flywheels; a substantially disc-shaped member non-rotatably connected with said other flywheel; and damper means arranged to oppose rotation of said flywheels relative to each other, said damper means at least comprising energy storing means acting in the circumferential direction of said flywheels, and a friction generating device which is disposed between said flywheels, said friction generating device operating with friction axially between said member and said one flywheel and comprising a friction ring and a stressed energy storing element acting in the axial direction of said flywheels.
0. 13. Apparatus for compensating for variations of torque, especially for fluctuations of torque which is transmitted between a combustion engine and an input means of a transmission, comprising at least two flywheels including first and second flywheels, said flywheels being rotatable relative to each other, said first flywheel being connectable with the engine and said second flywheel being connectable with the input means of the transmission; a damper device arranged to oppose rotation of said flywheels relative to each other and consisting at least of energy storing elements acting in the circumferential direction of said flywheels; a friction clutch carried by one of said flywheels; an antifriction roller bearing disposed between said flywheels and axially fixed by said one flywheel; a substantially disc-shaped member; and means for form-lockingly and nonrotatably connecting said member to said one flywheel radially inwardly of said energy storing elements, said one flywheel having a shoulder and said bearing being confined between said shoulder and said member.
0. 11. Apparatus for compensating for variations of torque, especially for fluctuations of torque which is transmitted between a combustion engine and an input means of a transmission, comprising at least two flywheels including first and second flywheels, said flywheels being rotatable relative to each other, said first flywheel being connectable with the engine and said second flywheel being connectable with the input means of the transmission; a friction clutch carried by one of said flywheels; a damper device arranged to oppose rotation of said flywheels relative to each other and consisting at least of energy storing elements acting in the circumferential direction of said flywheels; an antifriction bearing disposed between said first and second flywheels and axially secured by said one flywheel, said bearing having an inner race and an outer race and said one flywheel having a first shoulder; a disc-shaped member form-lockingly and nonrotatably connected with said one flywheel, said outer race being confined between said first shoulder and said disc-shaped member and the other of said flywheels having a second shoulder engaged by said inner race and provided on a protuberance of said other flywheel, said protuberance extending from an output element of the engine; a sheet metal member; and fastener means securing said sheet metal member to said other flywheel, said sheet metal member including a radially outer portion and said inner race being secured between said radially outer portion and said second shoulder.
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The torsion damping apparatus 1 of
The flywheels 3 and 4 are or can be coaxial and can perform limited or unlimited angular movements relative to each other against the opposition of a composite damper including a damper unit 13, a friction generating unit 13a and a slip clutch 14 which is connected in series with the damper unit 13.
The torsion damping apparatus 1 further comprises a bearing means 15 which is interposed between the flywheels 3 and 4 and, in the embodiment of
The improved torsion damping apparatus 1 further comprises means for impeding the transfer of heat from the friction- and heat-generating surfaces 9b, 4a to the bearing means 15. In the embodiment of
The illustrated thermal barrier 24 comprises two rings 25, 26 which are mirror symmetrical to each other with reference to a plane that is disposed between them and is normal to the axes of the flywheels 3, 4 and antifriction bearing 16. Each of the rings 25, 26 has a substantially L-shaped cross-sectional outline with a cylindrical section 25a, 26a which surrounds the external surface of the outer race 17 and a radially inwardly extending washer-like section 25b, 26b which extends along the respective end face of the outer race 17 and toward and along the respective end face of the inner race 19. The radially innermost annular portions or lips of the radial sections 25b, 26b bear axially against the respective end faces of the inner race 19. Thus, the sections 25b, 26b constitute sealing elements which reduce the likelihood of penetration of foreign matter into the annular bearing clearance between the races 17, 19 as well as the likelihood of escape of lubricant from such clearance. The sealing action of radial sections 25b, 26b of the rings 25, 26 is enhanced by discrete means for biasing the radially innermost portions of such radial sections against the adjacent end faces of the inner race 19. The biasing means comprises two diaphragm springs 27, 28. The radially outermost portion of the diaphragm spring 27 reacts against a shoulder provided therefor on a disc 30 which is affixed to the flywheel 4 by rivet-shaped distancing elements 29, and the radially innermost portion of the diaphragm spring 27 bears against the radially innermost portion of the radial section 25b of the ring 25. The radially outermost portion of the diaphragm spring 28 reacts against a shoulder of the flywheel 4, and its radially innermost portion bears against the radially innermost portion of the radial section 26b of the ring 26.
In order to simplify and facilitate the assembly of the antifriction bearing 16 with the flywheels 3 and 4, the cylindrical sections 25a, 26a of the rings 25, 26 are forcibly fitted onto the outer race 17 of the antifriction bearing 16 in a first step before the bearing 16 and the rings 25, 26 thereon are forcibly inserted into the recess 18 of the flywheel 4. The bearing 16 and the rings 25, 26 are thereupon additionally secured against axial movement relative to the flywheel 4 in that the radial section 26b of the ring 26 bears against an internal shoulder 31 of the flywheel 4 and the radial section 25a of the ring 25 is caused to abut against the disc 30 which, as mentioned above, is affixed to the flywheel 4 by the distancing elements 29.
The damper unit 13 includes the disc 30 and a second disc 33 which is held at a fixed distance from the disc 30 by the aforementioned rivet-shaped distancing elements 29 which are anchored in the flywheel 4. The shanks of such distancing elements extend through a flange 32 which is disposed between the discs 30 and 33. The discs 30, 33 cannot rotate relative to each other and share all angular movements of the flywheel 4. The flange 32 shares all angular movements of the flywheel 3. The discs 30, 33 and the flange 32 are provided with neighboring windows for energy storing devices in the form of circumferentially acting coil springs 34 which oppose angular movements of the flywheels 3 and 4 relative to each other, i.e., such coil springs resist angular movements of the discs 30, 33 with reference to the flange 32 and vice versa.
The composite damper further includes the friction generating unit 13a which is active during each and every stage of angular movement of the flywheel 3 relative to the flywheel 4 and/or vice versa. The friction generating unit 13a acts axially between the disc 30 on the flywheel 4 and the flywheel 3, and includes an energy storing member in the form of a diaphragm spring 35 which is installed in prestressed condition between the disc 30 and a pressure applying washer 36. The diaphragm spring 35 can react against the flywheel 3 to bear against the washer 36 which, in turn, urges a friction ring 37 against the adjacent side of the disc 30 on the flywheel 4. The axial stress which is applied by the diaphragm spring 35 is taken up by the antifriction bearing 16.
The flange 32 constitutes the input element of the damper unit 13 as well as the output element of the slip clutch 14. The input element of the slip clutch 14 is constituted by two discs 38, 39 which are maintained at a fixed axial distance from each other and are non-rotatably secured to the flywheel 3. The means for non-rotatably securing the disc 39 to the flywheel 3 comprises an annulus of rivets 40. The disc 38 is provided with an annulus of axially extending peripheral fingers or lugs 38a which extend into adjacent peripheral notches 41 of the disc 39 so that the two discs are held against angular movement relative to one another. The flange 32 has radially outwardly extending arms 42 which are clamped between the discs 38 and 39 by a diaphragm spring 43 which urges the discs 38 and 39 toward each other. The diaphragm spring 43 reacts against the flywheel 3 and bears against the disc 38 in a direction to urge the latter axially toward the disc 39. The arms 42 of the flange 32 alternate with windows which are provided in the discs 38, 39 and receive energy storing devices in the form of coil springs 44 which can be engaged by the respective arms 42 and constitute stops that determine the extent of angular displacement of the parts of the slip clutch 14 relative to each other.
It has been found that the thermal barrier 24 between the friction clutch 7 and the bearing means 15 is capable of prolonging the useful life of the bearing means as well as of ensuring more satisfactory operation of the damper (13, 13a, 14) between the flywheels 3 and 4. This is due to the fact that the thermal barrier 24 greatly reduces the transfer of heat to the bearing means 15 even though it takes up little room and is assembled of a small number of simple, compact and inexpensive parts each of which can be mass-produced in available machinery. Extensive experiments with the improved torsion damping apparatus (wherein the bearing means is installed directly between the two flywheels 3 and 4 and wherein the angular movements of the flywheels relative to each other must be damped by one or more discrete or interlinked dampers) indicate that, in the absence of any preventive or precautionary measures, heat energy which is released when the friction clutch 7 is engaged subjects the bearing means between the flywheels to very pronounced thermal stresses which entail unsatisfactory operation and frequently rapid destruction of the bearing means as well as unsatisfactory operation of the damper or dampers. The likelihood of rapid destruction of the bearing means is especially pronounced if the bearing clearance or tolerance between the inner and outer races is small or very small. Repeated pronounced heating and cooling of the parts cf such bearing means entails substantial thermally induced expansion and contraction whereby the rolling elements between the two races are likely to seize in response to expansion cf the races which, in turn, entails rapid destruction of the rolling elements and of the tracks which are machined into the races. All this can be avoided by the advent of the present invention, i.e., by the provision of a thermal barrier which at least impedes the transfer of heat to the bearing means.
Another important advantage of the improved apparatus is that the lubricant (such as oil or grease) in the bearing clearance between the races of the bearing is much less likely to be overheated and to escape from the bearing. This, too, contributes to longer useful life of the bearing means and of the entire torsion damping apparatus. Moreover, portions or sections of the rings 25, 26 which constitute or form part of the improved thermal barrier 24 can serve as an effective means for sealing the bearing clearance between the races 17 and 19 to thereby even further reduce the likelihood of escape of excessive quantities of lubricant from the interior of the antifriction bearing 16. The aforediscussed plastic, ceramic and/or metallic materials have been found to constitute highly satisfactory thermal insulators which can protect the antifriction bearing 16 and the units of the composite damper for extended periods of time, even if the friction clutch 7 is continuously engaged and/or is caused or permitted to slip (with attendant pronounced generation of heat) at frequent and relatively long intervals.
It was further ascertained that the placing of the thermal barrier directly between the antifriction bearing 16 and the adjacent portion of the flywheel 4 (i.e., of that flywheel which is directly heated by the friction clutch 7) contributes significantly to adequate shielding of the bearing means 15 from excessive heat while, at the same time, allowing for relatively simple and inexpensive installation of the thermal barrier in the torsion damping apparatus. Of course, it is equally possible to employ two or more thermal barriers or to provide one or more thermal barriers in the body of the flywheel 4 and out of direct contact with the antifriction bearing 16 but in the path of transfer of heat energy from the friction generating surfaces 9b, 4a to the bearing 16.
The positions of the recess 18 and protuberance 20 can be reversed, i.e., the protuberance can be provided on the central portion of the flywheel 4 and the flywheel 3 is then formed with a recess which receives at least a portion of the protuberance on the flywheel 4, at least a portion of the bearing means on such protuberance and at least a portion of the thermal barrier. The thermal barrier is then preferably installed within the inner race (which surrounds the protuberance of the flywheel 4) in order to prevent overheating of the bearing means 15. This is shown in FIG. 5.
The thermal barrier 24 of
The chambers 117a, 117b respectively receive discrete sealing means in the form of O-rings 145, 146 which cooperate with the lips 125c, 126c and diaphragm springs 127, 128, to prevent penetration of foreign matter into the bearing clearance between the races 117, 119 as well as to prevent the escape of lubricant (e.g., grease) from such clearance. The dimensions of the chambers 117a, 117b and of the O-rings 145, 146 are selected in such a way that the O-rings are at least slightly compressed so as to reliably prevent the escape of lubricant from the clearance for the rolling elements of the antifriction bearing 116.
The diaphragm spring 127 and/or 128 can be omitted if the corresponding radial section 125b and/or 126b is sufficiently elastic to adequately bear against the respective end face of the inner race 119 when the antifriction bearing 116 is properly mounted on the protuberance 120 of the flywheel 3 and is adequately received in the recess 118 of the flywheel 4. The same applies for the radial sections 25b, 26b of the rings 25, 26 and for the diaphragm springs 27, 28 of the apparatus 1 which is shown in FIG. 1. Thus, all that is necessary is to make the rings 25, 26 and/or 125, 126 of a suitable elastomeric material and to mount these rings in such a way that their radial sections 25b, 26b and/or 125b, 126b are elastically deformed in fully assembled condition of the respective apparatus to adequately bear against the inner race 19 or 119 and to thus prevent escape of lubricant from the clearance between the races 17, 19 or 117, 119.
The O-rings 145 and 146 even further reduce the likelihood of escape of lubricant from the bearing clearance between the races 117 and 119, even if the lubricant is subjected to the action of very pronounced centrifugal forces.
Referring to
The diaphragm spring 227 reacts against the disc 230 and biases the ring-shaped thermal barrier 225 in the direction of taper of its frustoconical surfaces 225a', 225a", i.e., in a direction to cause the section 225a to penetrate deeper into the recess 218.
The thermal barrier of
The material of the ring-shaped thermal barrier 225 and of the sealing element 226 is preferably a good insulator of heat.
The torsion damping apparatus which embodies the structure of
It is further within the purview of the invention to provide the improved torsion damping apparatus with a thermal barrier which need not include any prefabricated parts in the form of rings and/or washer-like sealing elements. For example, and as shown in
The injection or another mode of introduction of a flowable plastic, metallic or ceramic material into the space between the surfaces bounding the recess 318 of the flywheel 4 and the exterior of the antifriction bearing 316 is especially advantageous and desirable if the bearing 316 is a commercially available antifriction bearing which is already provided with sealing elements 360 that prevent uncontrolled escape of lubricant from the space between the two races. As mentioned above, all that is necessary is to adequately select the dimensions of the surfaces bounding the recess 318 so as to provide sufficient room for introduction of a flowable material which is to form the thermal barrier 324 and is to be integral with the outer race 317 and/or with the flywheel 4.
The disc 330 is applied subsequent to introduction of the outer race 317 into the recess 318, and the disc 320 is attached to the flywheel 3 to hold the inner race 319 against axial movement.
Referring to
A damper 413 is installed between the flywheels 403 and 404 to yieldably oppose the aforementioned angular movements of the flywheels relative to each other. The apparatus 401 further comprises antifriction bearing means 414 here shown as comprising a ball bearing 415 with a single row of spherical rolling elements 415a between an outer race 416 and an inner race 418. The race 416 extends into an internal annular groove 417 of the flywheel 404, and the race 418 surrounds a hub-shaped central portion or protuberance 419 of the flywheel 403. The protuberance 419 extends axially of the flywheel 404 in a direction away from the output element 405.
The inner race 418 is a press fit on the protuberance 419 and is held against axial movement on such protuberance by a radially outwardly extending shoulder 420 of the flywheel 403 in cooperation with a washer-like retainer 421 which abuts the adjacent end face 422 of the protuberance 419 and is separably affixed to the latter by screws 423 or by analogous fastener means.
In accordance with a feature of the embodiment of
As can be best seen in
The radially extending legs 425b, 426b of the rings 425, 426 perform the additional function of confining the lubricant (normally grease) for the rolling elements 415a in the space between the races 416 and 418 of the ball bearing 415. The damping and confining or sealing action of the legs 425b, 426b can be enhanced and maintained at a selected optimum value or within a predetermined optimum range by the provision of means for biasing the lips 434, 435 against the respective end faces 437, 438 of the inner race 418. Such biasing means comprises a first dished spring 427 whose radially outermost portion reacts against an internal shoulder 430a of a disc 430 and whose radially innermost portion bears against the lip 434 of the leg 425b, and a second dished spring 428 whose radially outermost portion reacts against an internal shoulder 431 of the flywheel 404 and whose radially innermost portion bears against the lip 435 of the leg 426b. The disc 430 is affixed to the flywheel 404 by a set of rivets 429.
In order to simplify the assembly of the thermal barrier 424 with the antifriction bearing 415, the annular portions 425a, 426a of the rings 425, 426 are first force-fitted onto the peripheral surface of the outer race 416 before the rings 425, 426 are introduced into the recess 417 of the flywheel 404. The antifriction bearing 415 is maintained in a predetermined axial position with reference to the flywheel 4 404 because the outer side of the properly installed radially extending leg 426b abuts an internal shoulder 431a of the flywheel 404 and the radially outermost portion of the outer side of the leg 425b abuts the adjacent side of the aforementioned disc 430.
The damper 413 between the flywheels 403 and 404 further comprises the aforementioned disc 430 as well as a second disc 440 whose inner diameter is larger than that of the disc 430. The rivets 429 are configurated in such a way that they maintain the discs 430, 440 at a fixed axial distance from the surface 404a of the flywheel 404 as well as from each other. The discs 430, 440 flank (i.e., they are disposed at the opposite sides of) a flange 439 whose radially outwardly extending prongs 439a are secured to the flywheel 403 by rivets 442. The flange 439 and the discs 430, 440 have registering windows for energy storing elements in the form of coil springs 441 whose function is to oppose angular movements of the discs 430, 440 and flange 439 relative to each other.
The arrow 443 denotes in
The extent to which the flywheels 403 and 404 can turn relative to each other is determined by the length of circumferentially extending slots in the flange 439. Such slots receive portions of the respective rivets 429.
An important advantage of the torque transmitting apparatus of
The apparatus of
The improved thermal barrier can operate satisfactorily with a single ring 425, 525 or 426, 526. The utilization of two rings is preferred at this time because two rings ensure a more satisfactory sealing of the aforediscussed annular space between the races 416, 418 or 516, 518, because two rings can establish a highly satisfactory thermal barrier between the flywheel 404 or 504 and the bearing 415 o 515, and also because two rings (especially when used with two discrete dished springs or the like) can provide a highly satisfactory damping action by opposing the angular movements of the flywheels 403, 404 or 503, 504 relative to each other.
The apparatus 601 further comprises means for yieldably opposing angular movements of the components 603 and 604 relative to each other. Such opposing means comprises a first damping unit 613, a second damping unit 614 in series with the unit 613, and a friction generating device 613a. The exact construction of the units 613, 614 and friction generating device 613a forms no part of the present invention. Reference may be had to the aforementioned copending applications of the assignee and to the embodiments of
The apparatus 601 still further comprises bearing means 615 including at least one radial antifriction bearing 616 having an outer race 617, an inner race 619 and an annulus of spherical rolling elements 616a between the two races. The outer race 617 is disposed in an axial recess or bore 618 of the component 604, and the inner race 619 is preferably a press-fit on a centrally located cylindrical protuberance 620 of the component 603. The protuberance 620 extends axially in a direction away from the crankshaft 605 and into the bore 618 of the component 604. The inner race 619 abuts a stop in the form of a shoulder 621 of the protuberance 620 and is held against axial movement away from such shoulder by a disc-shaped retainer 622 which is secured to the adjacent end face 620a of the protuberance 620 by a set of screws 623 or other suitable fasteners.
The apparatus 601 also comprises a number of means for impeding or preventing the transmission of heat between the friction surface 604a and the radial antifriction bearing 616. The latter is disposed radially inwardly of the friction linings on the clutch plate 609. One of the heat transmission preventing or impeding means comprises a thermal barrier 624 composed of two coaxial rings 625 and 626 each having a substantially L-shaped cross-sectional outline. The axially extending (cylindrical) portions 625a, 626a of the rings 625, 626 surround the major part of the external surface of the outer race 617 and are received in the bore 618 of the second component 604. The radially extending (washer-like) portions 625b, 626b of the rings 625, 626 are adjacent the respective end faces of the races 617, 619 and are biased against the corresponding end faces of the inner race 619 by energy storing elements in the form of diaphragm springs 627, 628, respectively. The radially extending portions 625b, 626b not only intercept some of the heat but also serve to seal the space between the races 617, 619 so as to prevent uncontrolled escape of grease for the rolling elements 616a. The radially outermost portion of the diaphragm spring 627 reacts against a shoulder of a disc 630 which is affixed to the component 604 by rivets 629, and the radially innermost portion of the spring 627 bears against the radially innermost part of the portion 625b. The diaphragm spring 628 has a radially outermost portion which reacts against an internal shoulder of the component 604 and a radially innermost portion which bears against the radially innermost part of the portion 626b. The diameter of the surface surrounding the bore 618 is sufficiently large to allow for the placing of rings 625, 626 onto the outer race 617 in a manner as shown in FIG. 9. The material of the rings 625, 626 is selected in such a way that they constitute a thermal insulator which impedes the transfer of heat between the friction surface 604a of the component 604 and the radial bearing 616. The bearing 616 is held against axial movement relative to the component 604 by the rings 625, 626 in that the ring 625 abuts the disc 630 and the ring 626 abuts an internal shoulder 631 of the component 604. As mentioned before, the rivets 629 fix the disc 630 to the component 604.
The damping unit 613 comprises the aforementioned disc 630 and a second disc 633. The discs 630, 633 are disposed at the opposite sides of a flange 632 and are held (by the rivets 629) against axial movement relative to each other and relative to the component 604. The flange 632 has windows (not specifically referenced) which register with windows in the discs 630, 633 and serve to receive energy storing elements in the form of coil springs 634. The coil springs 634 yieldably oppose angular movements of the flange 631 and discs 630, 633 relative to each other. The flange 632 is rotatable relative to the component 604, together with the component 603.
The friction generating device 613a can be said to constitute a part of the damping unit 613 and is designed to resist each and every angular movement of the components 603 and 604 relative to each other. This friction generating device is installed between the disc 630 and the component 603 and comprises an energy storing device in the form of a diaphragm spring 635 which reacts against the disc 630 and bears upon a ring 636. The ring 636, in turn, urges a washer 637 against the component 603. The force which is transmitted by the diaphragm spring 635 to the disc 630 is taken up by the radial bearing 616.
The flange 632 is the input member of the damping unit 613 as well as the output member of the damping unit 614. The input member of the damping unit 614 includes two axially spaced-apart discs 638, 639 which are non-rotatably secured to the component 603. The disc 639 is affixed to the component 603 by rivets 640. The periphery of the disc 638 is provided with integral projections in the form of axially extending lugs 638a which extend into complementary recesses 641 of the disc 639. This ensures that the discs 638, 639 can move axially toward and away from each other but cannot perform any angular movements with respect to one another. The flange 632 has radially extending arms or teeth 642 which are clamped between the discs 638 and 639. For this purpose, the discs 638, 639 are biased toward each other by a diaphragm spring 643. The spring 643 reacts against the component 603 and bears upon the disc 638 in a direction to urge the disc 638 toward the disc 639. The discs 638, 639 have windows which register with each other and with tooth spaces between the arms 642 and serve to receive energy storing elements in the form of coil springs 644.
In accordance with a feature of the invention which is shown in
In accordance with a presently preferred embodiment of the invention, the cross-sectional areas of the passages 645 increase in a direction from a surface 646 radially inwardly of the friction surface 604a toward an additional surface 647 of the component 604 opposite the friction surface 604a. The surface 647 faces the damping units 613 and 614. The component 604 has internal surfaces which surround the passages 645 and each of which includes a first or inner portion 648 nearer to the common axis of the components 603, 604 and extending in at least substantial parallelism with such axis, and a second or outer portion 649 which is more distant from the common axis of the components 603, 604 and diverges radially outwardly away from the common axis toward the periphery of the component 604. At least a portion of each surface portion 649 has a substantially convex outline as can be readily seen in the lower portion of FIG. 9. The shallow leftmost portion of each passage 645 is provided in the second surface 647 of the component 604 and extends radially at least along a portion (x) of the width of the friction surface 604a as considered in the radial direction of the flywheel 602. The surfaces bounding the passages 645 resemble those of air circulating vanes or blades on an air impeller and cause streams of air to flow through the passages 645 in a direction from the friction surface 604a toward the additional surface 647 of the component 604. This entails a pronounced cooling of the entire flywheel 602 and greatly reduces the amount of heat which is transmitted from the friction surface 604a to the bearing 616. Thus, that portion of the component 604 which is formed with the passages 645 can be said to constitute a thermal barrier which impedes the transfer of heat from the surface 604a to the antifriction bearing 616. In addition, streams of air flowing through the passages 645 effect a substantial cooling of component parts of the damping means 613, 614, 613a because such streams flow along the discs 633 and 639 and a portion of each such stream can escape, for example, through the windows of the discs 630, 633 and flange 632. As mentioned before, such windows are provided for the energy storing springs 634.
The combined length of the passages 645 (in the circumferential direction of the component 604) can be between 20 and 70% of the total length of the corresponding portion of the component 604. In the embodiment of
It is also within the purview of the invention to increase the length of the passages 645. For example, if the radial bearing 616 can stand reasonably pronounced thermal stresses, or if the transmission of pronounced thermal stresses is impeded in another way, the length of the illustrated passages 645 can be increased as shown in
Since the webs 651 and/or 652 constitute relatively narrow portions of the component 604 and alternate with passages 645, they act not unlike restrictors or throttles to the transmission of heat from the friction surface 604a toward the bearing 616. Thus, the corresponding portion of the component 604 is cooled by streams of air flowing through the passages 645, and the webs 652 constitute restrictors in that they oppose the transmission of heat to the radial bearing 616 so that the useful life of such bearing is much longer than in conventional apparatus. In view of the aforediscussed distribution of material of the component 604 in the region of the circle whose diameter is shown at 650, and in view of the distribution of passages 645 in the form of an annulus which is disposed between the friction surface 604a and the radially innermost portion 653 of the component 604 (i.e., radially outwardly of the bearing 616), heat which is generated in response to engagement of the friction clutch 607 can entail some rise in the temperature of the radially innermost portion 653 but not to a value which could entail damage to the bearing 616. The feature that the bearing 616 is not subjected to excessive thermal stresses is attributable, to a considerable extent, to the fact that the major part of the mass of the component 604 is located radially outwardly of the passages 645.
The placing of rivets 629 into the webs 652 exhibits the advantage that the rivets dissipate substantial quantities of heat which would otherwise pass through the webs 652 and into the radially innermost portion 653 of the component 604. Moreover, the rivets 629 transmit heat to the discs 630, 633 which dissipate such heat into the surrounding atmosphere. In other words, the rivets 629 ensure that a substantial percentage of heat which would have passed through the webs 652 and into the portion 653 is transmitted to parts (630, 633) having large exposed surfaces to ensure rapid dissipation of transmitted heat to atmospheric air.
The heat barrier 624 including the rings 625, 626 constitutes an optional feature of the apparatus of
The passages 645 are provided in addition to those passages which are desirable or necessary in the component 604 for other purposes, for example, to facilitate assembly of the apparatus 601 by providing paths for the tool which is to rotate the bolts 605 and/or other tools. It is also known to provide the components of a composite flywheel with openings for withdrawal of lubricant and for other purposes. The passages 645 are provided for the specific purpose of reducing the transfer of heat between the antifriction bearing which is interposed between the components of the flywheel and the friction surface of the component which comes into contact with the linings of the clutch plate 609. The passages 645 extend all the way between the surfaces 604a and 647 of the component 604 so as to ensure the aforedescribed desirable circulation of air streams and attendant cooling of the corresponding portion of the component 604 radially outwardly of the portion 653 which supports and surrounds the outer race 617 of the antifriction bearing 616. It has been found that the passages 645 contribute significantly to the useful life of the bearing 616 because the bearing is shielded from excessive thermal stresses which develop when the friction clutch 607 is actuated and which are likely to rapidly destroy the bearing in the absence of any remedial measures in addition to those which are already known in the art. The provision of passages 645 is particularly desirable in apparatus which employ antifriction bearings whose components are assembled with a minimum of play so that pronounced and rapid heating or cooling of such bearings could entail extensive thermally induced distortion and attendant jamming of the parts. In fact, such excessive thermally induced distortion can lead to seizing with immediate destruction of the bearing. The streams of air which flow through the passages 645 further ensure adequate cooling of lubricant for the rolling elements 616a of the bearing 616 regardless of whether such lubricant is oil or grease. Adequate cooling (or prevention of overheating) of the lubricant also prolongs the useful life of the bearing 616.
The passages 645 can be configurated in a number of different ways without departing from the spirit of the invention. It has been found that elongated passages in the form of arcuate slots are particularly advantageous because they ensure the flow of large quantities of air and reduce the combined length of webs 652 or webs 651, 652. The aforedescribed configuration of surfaces 648, 649 which surround the passages 645 is desirable and advantageous because such surfaces act not unlike the surfaces of vanes or blades and ensure forced circulation of air in the region of the circle including the diameter 650. The placing of passages 645 close to the radially innermost portion 653 of the component 604 also contributes to a more reliable prevention of overheating of the bearing 616. The provision of relatively shallow recesses which are provided in the surface 647 and constitute the radially outermost portions of the passages 645 ensures that a large percentage of air which is heated during flow through the passages is caused to flow radially outwardly and away from the bearing 616. The surfaces surrounding the passages can be said to constitute a radial fan which draws air from the space radially inwardly of the friction surface 604a and causes streams of air to flow first axially and thereupon radially outwardly toward the periphery of the component 604. This effectively reduces the likelihood of flow of large quantities of heated air toward the bearing 616. The aforementioned configuration (convexity) of the surface portions 649 in the passages 645 also contributes to a desirable flow of heated air radially outwardly and away from the radially innermost portion 653.
While it is possible to provide the passages 645 in non-uniform or irregular distribution, a uniform or regular distribution is preferred at this time because it ensures predictable cooling of each and every portion of the component 604 in the region of the webs 651 and 652.
As mentioned before, the mass of the component 604 radially outwardly of the passages 645 is much larger than the mass of the radially innermost portion 653. Since the flow of heated air is radially outwardly, eventual heating of the major part of the component 604 radially outwardly of the passages 645 does not entail an overheating of the portion 653 and bearing 616.
The streams of air which flow through the passages 645 bring about a desirable cooling of the elements of the damping means 613, 613a, 614. This prolongs the useful life of such damping means and hence the useful life of the entire apparatus. Moreover, the streams of air can adequately cool the first component 603 of the composite flywheel 602.
Without further analysis, the foregoing will so fully reveal the gist of the present invention that others can, by applying current knowledge, readily adapt it for various applications without omitting features that, from the standpoint of prior art, fairly constitute essential characteristics of the generic and specific aspects of our contribution to the art and, therefore, such adaptations should and are intended to be comprehended within the meaning and range of equivalence of the appended claims.
Reik, Wolfgang, Elison, Hans-Dieter
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Executed on | Assignor | Assignee | Conveyance | Frame | Reel | Doc |
Jan 08 2001 | LuK Lamellen und Kupplungsbau Beteiligungs KG | (assignment on the face of the patent) | / | |||
Jan 16 2001 | LuK Lamellen und Kupplungsbau GmbH | LuK Lamellen und Kupplungsbau Beteiligungs KG | CHANGE OF NAME SEE DOCUMENT FOR DETAILS | 012937 | /0763 |
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