Installation for Damping Torsional Vibrations in a Gear Drive, Especially Between the Crankshaft and an Output Shaft of Internal Combustion Engines

The present invention relates to an installation for damping torsional vibrations in a gear drive, especially between the crankshaft and an output shaft of internal combustion engines as disclosed in the German Pat. No. 25 39 424.

In this prior art installation the output shaft serves as balancing shaft for reaction moments during rotational speed changes of the engine and as auxiliary drive shaft for a generator which serves as balancing mass. By reason of the operating conditions resulting therefrom the friction clutch is constructed as main drive connection and the elastic coupling serves as damping means, when the transmission torque of the friction clutch is exceeded. The friction clutch therefor involves a large space requirement and high structural expenditures. The elastic coupling is built into the drive gear. This prior art installation is therefore not suited for the transmission of the entire output torque of the engine onto the output shaft with simultaneous damping of torsional vibrations because the prior art arrangement would then require impractically large dimensions. Furthermore, with this prior art installation the individual structural components such as the gear, a part of the elastic coupling and the friction clutch are arranged individually on the balancing shaft and are combined into a functional unit. This arrangement is costly in its assembly.

It is therefore the object of the present invention to provide an installation for the output of the engine, especially of the crankshaft of an internal combustion engine, to an output shaft for a series-connected change-speed transmission or another aggregate, in which at least the gear wheel, a part of the elastic coupling and the friction clutch form a structural and functional unit adapted to be preassembled which is space-saving, cost favorable and operationally reliable as well as simple to assemble.

The underlying problems are solved according to the present invention in that the elastic coupling is formed of an inner coupling half and of an outer coupling half with webs each as rotary abutments for interconnected elastic elements, in that the outer coupling half is rigidly connected with the gear wheel and in that friction clutch is arranged between end faces of the gear wheel and the webs of the outer coupling half. A compact construction with low structural expenditures and favorable properties for the assembly is achieved in this manner, in particular the friction clutch can be held coaxially to the axis of the shaft by a prestressed spring element. As a result thereof, a preassembled unit including at least the outer clutch half, the gear wheel and the friction clutch can be assembled on the output shaft without special expenditure. A space-saving and operationally reliable installation is attained in that the elastic coupling transmits the output torque and the friction clutch dampens the torsional vibrations. This can be achieved if the elastic coupling transmits predominantly the torque between the gear wheel and the output shaft, if the friction clutch serves as friction damper for torsional vibrations between gear wheel and output shaft, and if the friction clutch includes an entrainment member nonrotatable with the output shaft and coordinated to the webs of the outer coupling half at the end face thereof, a thrust ring and a friction ring facing the end face of the gear wheel as well as a cup spring arranged between entrainment member and thrust ring which is prestressed during the axial assembly of gear wheel and outer coupling half. A friction clutch simple in construction is achieved thereby in combination with this functional division, which is of particularly short construction in the axial direction. The structural length realized thereby can be utilized in an advantageous manner for the configuration of the rubber elements between the inner and outer coupling half, whereby the external dimensions of the outer coupling half can be kept small.

A structurally simple arrangement of the installation is achieved in that according to the present invention the installation is axially clamped together in the end area of the output shaft between a shaft collar and a separate flange bushing of a connecting arrangement of the output shaft. This arrangement further entails a non-rotatable clamped mounting for the entrainment member of the friction clutch so that a simple constructive design without separate form-locking connecting elements results for the entrainment member which drives the spring loaded thrust ring. Additionally, the cup spring of the friction clutch is automatically and correspondingly prestressed between entrainment member and thrust ring by the axial clamping action of the installation by a shoulder of the flange bushing abutting end-face at the hub. Moreover, the rotatable bearing support of the installation in a housing bore which is separated centrally by means of a shaft bearing on the hub of the gear wheel entails the advantage that the installation can be combined with the output shaft and the further connecting part outside of the housing into a larger assembly unit.

Furthermore, the gear wheel of the installation according to the present invention may be combined with a restraining or bracing gear wheel of known type for achieving a gear drive that operates without play. In an internal combustion engine having a crank drive with high non-uniformities and low flywheel mass, for example, a change-speed transmission with comparably large flywheel mass may be coupled to the crankshaft by way of the installation in accordance with the present invention if constructed as mentioned hereinabove without the danger that the teeth of the installation are mechanically overloaded by occurring torsional vibrations and that noises are produced by abutment changes of the tooth flanks.

Finally, for the simplification of the assembly of the restraining gear wheel, a slotted spring ring which is prestressed in the circumferential direction, may be arranged at the gear wheel. The restraining gear wheel which is offset in the circumferential direction with its teeth with respect to the teeth of the gear wheel, is drivingly connected with the spring ring by means of a fitting or dowel pin. As a result thereof, the extent of stressing is determined prior to the engagement of the gear wheel into the counter gear and does not have to be produced only by additional rotation respectively stressing of the spring ring prior to the meshing engagement of the gear wheels.

These and other objects, features and advantages of the present invention will become more apparent from the following description when taken in connection with the accompanying drawing which shows, for purposes of illustration only, one embodiment in accordance with the present invention, and wherein:

The single FIGURE is an elevational view, partially in axial cross section, through an installation in accordance with the present invention for damping torsional vibrations between a crankshaft and an output shaft of an internal combustion engine.

Referring now to the single figure of the drawing, this figure illustrates an installation generally designated by reference numeral 1 for damping torsional vibrations in a gear drive generally designated by reference numeral 2 which includes gear wheels 3 and 4. The gear wheel 3 is thereby arranged on a crankshaft of an internal combustion engine (not shown). An output shaft 6 is arranged in the housing 5 of the internal combustion engine in parallel to the crankshaft. The output shaft 6 is pperatively connected at one end by way of a flywheel 7 and a separating clutch (not shown) with a change-speed transmission and at the other end thereof with auxiliary aggregates.

The gear wheel 4 of the installation 1 is force-lockingly connected with the output shaft 6 by way of a friction clutch 8 and is non-rotatably connected with the output shaft 6 by an elastic coupling generally designated by reference numeral 9 which is connected in parallel thereto. The elastic coupling 9 consists of an inner coupling half 10 and of an outer coupling half 11 which include each radially directed webs 12 and 13, respectively, as rotary abutments for interconnected rubber elements 14. The outer coupling half 11 is rigidly connected with the gear wheel 4 preferably by rivets 15. Prior to the connection of these two structural parts 4 and 11, the friction clutch 8 is arranged between the end faces 16 and 17 of the gear wheel 4 and the webs 12 of the outer coupling half 11. The friction clutch 8 includes an entrainment member 18 coordinated end-face to the webs 12 of the outer coupling half 11, a thrust ring 19 and a friction ring 20 facing the end face 16 of the gear wheel 4. The cup spring 21 is arranged between the entrainment member 18 and the thrust ring 19. This cup spring 21 is prestressed preliminary during the axial assembly of gear wheel 4 and outer coupling half 11 for the rigid connection by means of the rivets 15 and as a result thereof the friction clutch 8 is held centered until assembly of the preassembled unit on the output shaft 6.

For purposes of achieving a space-saving and operationally reliable installation 1, the friction clutch 8 serves as friction damper for torsional vibrations between gear wheel 4 and output shaft 6, whereby the elastic coupling 9 transmits predominantly the torque between gear wheel 4 and output shaft 6. Additional structural length for the rubber cushions 14 of the elastic coupling 9 which transmit the torque, is achieved by means of the friction clutch which can be built relatively short in the axial direction, so that the outer coupling half 11 can be kept small in its outer diameter.

The gear wheel 4 includes a hub 22 which carries a roller-bearing 23 at the outer circumference thereof on the side of the gear wheel opposite the elastic coupling 9. The hub 22 further includes a slide bearing bore 24 for a flange bushing 25 coaxially arranged between gear wheel 4 and output shaft 6, which is non-rotatably connected with the flywheel 7 of an output clutch (not shown). The flange bushing 25, in its turn, is non-rotatably connected with the output shaft 6 by a spline shaft profile 26. Furthermore, the hub 22 of the gear wheel 4 which is angularly movable relative to the flange bushing 25, includes end faces 16 and 27 as friction surfaces. The end face 16 thereby cooperates with the friction ring 20 of the friction clutch 8 and the end face 27 with a further friction ring 29 of the friction clutch 8 arranged between the hub 22 and a shoulder 28 of the flange bushing 25.

The inner coupling half 10 of the elastic coupling 9 serving for the transmission of the driving torque is non-rotatably connected with the output shaft 6 by way of the spline shaft profile 26. Furthermore, the inner coupling half 10 abuts against a collar 31 of the output shaft 6 under interposition of a disc 30 and for purposes of axially securing in the opposite direction is held on the output shaft 6 by means of a tight or interference fit with the spline shaft profile 26. The preassembled unit formed by the output shaft 6 and the inner coupling half 10 is assembled with the other unit including gear wheel 4, outer coupling half 11 and friction clutch 8 under interposition of the loosely arranged rubber elements 14. The axial assembly of the two units is completed with the abutment of the entrainment member 18 at the inner coupling half 10, whereby the entrainment member 18 additionally abuts at the end faces 17 of the webs 12 of the outer coupling half 11. The gear wheel 4 and the outer coupling half 11 are centered with respect to the output shaft 6 by way of the flange bushing 25 which engages with a sliding fit into the spline shaft profile 26 of the output shaft 6, until assembly of the installation 1 in the housing 5. Furthermore, the flange bushing 25 extends through the hub 22 of the gear wheel 4 with such an axially projecting length that the flange bushing abuts against the end face 32 of the inner coupling half 10 by way of the interposed entrainment member 18. Such an axial distance is thereby selected between the end face 32 of the inner coupling half 10 and shoulder 28 of the flange bushing 25 that the entrainment member 8 is lifted off from the end faces 17 of the webs 12 of the outer coupling half 11 during axial clamping together by means of the clamping nut 25' and is held fast against rotation between the flange bushing 25 and the end face 32 of the inner coupling half 11 by the clamping action of the mounting. The entrainment member 18 is moved away from the end faces 17 of the webs 12 by an axial displacement of the gear wheel 4 together with the outer coupling half 11 by the shoulder 28 of the flange bushing 25. As a result of this displacement of the gear wheel 4 and of the outer coupling half 11 in the direction toward the disc 30 respectively the shaft collar 31, the cup spring 21 of the friction clutch 8 is at the same time prestressed to the final value. The friction clutch 8 and the elastic coupling 9 are so constructed and dimensioned that the friction clutch 8 dampens resonances which occur at low frequencies and large amplitudes whereas the rubber elements 14 of the elastic coupling 9 transmit the driving torque and dampen high frequencies of the torsional vibrations.

Finally, for achieving a gear drive 2 operating free of play, a restraining gear wheel 33 angularly movably arranged on the hub 22 is coordinated to the gear wheel 4. The constraining gear wheel 33 is non-rotatably but elastically connected with the gear wheel 4 by way of a slotted spring ring 34. The spring ring 34 includes at one end an angularly bent portion 35 for the support in the circumferential direction within an aperture 36 of the gear wheel 4. With its other end the spring ring 34 prestressed in the circumferential direction is secured or fixed at the gear wheel 4 by a fitting pin. The restraining gear wheel 33 is drivingly connected with the springy end of the spring ring 34 having the angularly bent end portion 35 by way of a further fitting pin 37. The restraining gear wheel 33 is positioned with its teeth offset in the circumferential direction with respect to the teeth of the gear wheel 4 by way of the driving connection. The restraining gear wheel 33 is axially secured at the gear wheel 4 by way of a cup spring 38 supported at the inner race of the roller bearing 23.

The installation 1 is supported with the output shaft 6 and further devices arranged at the ends thereof externally in a bore 39 of the housing 5 by way of the roller bearing 23. The housing 5 is divided in a center plane of the bore 39 and includes a circumferential groove 40, into which engages a radial flange 41 arranged at the outer race of the roller bearing.

While we have shown and described only one embodiment in accordance with the present invention, it is understood that the same is not limited thereto but is susceptible of numerous changes and modifications as known to those skilled in the art and we therefore do not wish to be limited to the details shown and described herein but intend to cover all such changes and modifications as are encompassed by the scope of the appended claims.