Durable torsional vibration damper

A torsional vibration damper for operation in an oil bath comprising an input flange for connecting to a drive motor, an output flange for connecting to a transmission, and a bow spring for the torsionally elastic coupling of the input flange to the output flange, where the bow spring is in contact radially on the outside with an encircling holding device that is formed on one of the flanges. At the same time, the holding device has an opening in the area of the bow spring, in order to enable a flow of oil through an area of contact of the bow spring with the holding device.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority from German Patent Application No. 10 2011 087 865.3, filed on Dec. 7, 2011, which application is incorporated herein by reference.

FIELD OF THE INVENTION

The invention relates generally to torsional vibration dampers, more specifically to torsional vibration dampers operating in an oil bath, and, even more specifically, to torsional vibration dampers operating in an oil bath in a drivetrain of a motor vehicle.

BACKGROUND OF THE INVENTION

A known serial torsional vibration damper comprises an input flange, an intermediate flange and an output flange, wherein a bow spring positioned radially outside is provided for the elastic transmission of torque from the input flange to the intermediate flange, and a compression spring positioned radially inside is provided for the elastic transmission of torque from the intermediate flange to the output flange. The input flange is usually shaped so that it receives the bow spring in a cup-like manner and supports it in a radially outer area, so that the bow spring is in contact with the input flange under the influence of centrifugal force. Such a flange is known as a retainer.

In particular, when used on a multi-cylinder reciprocating internal combustion engine, the torsional vibrations initiated by the internal combustion engine can result in deflections of the intermediate flange relative to the input flange with small angles of attack at a high frequency. In the contact area between the flange and the bow spring there develops a rubbing of steel on steel, which causes an abrasion of at least one of the frictional partners. The abrasion particles can be very fine, and can collect between the spring coils of the bow spring. That causes the abrasion particles to be further tumbled during the continuing operation of the torsional vibration damper and to be ground between the retainer and the bow spring, which further accelerates the wearing of both frictional partners.

SUMMARY OF THE INVENTION

The present invention broadly comprises a torsional vibration damper for operation in an oil bath, where the torsional vibration damper comprises the following: an input flange for connecting to a drive motor; an output flange for connecting to a transmission; a bow spring for the rotationally elastic connection of the input flange to the output flange; wherein the bow spring can be in contact radially on the outside with an encircling holding device that is formed on one of the flanges, characterized in that the holding device includes an opening in the area of the bow spring, in order to enable a flow of oil through an area of contact of the bow spring with the holding device.

A torsional vibration damper according to the invention, for operation in an oil bath, comprises an input flange for connecting to a drive motor, an output flange for connecting to a transmission, and a bow spring for the torsionally elastic coupling of the input flange to the output flange, where the bow spring may be in contact radially on the outside with an encircling holding device that is formed on one of the flanges. In this case, the holding device has an opening in the area of the bow spring, in order to enable a flow of oil through an area of contact of the bow spring with the holding device. At the same time, in certain operating conditions the bow spring may be in contact with the holding device, for example when a defined speed of rotation is exceeded.

An abrasion which occurs due to wear caused by friction of the bow spring on the holding element can thus be flushed away by the oil, so that the abrasion particles are removed from the area of contact of the bow spring with the holding device, minimizing wear. The abrasion particles can be kept back from the oil, for example, by means of a conventional filter in an oil circuit. The service life of the torsional vibration damper, and in particular of the bow springs, can be prolonged by the oil flushing, without requiring expensive measures such as browning or nitrifying to increase the robustness of the bow springs and/or of the holding device.

In a preferred embodiment, the opening is situated in the area of a radial vertex of the holding device. Oil that is pressed out by centrifugal force in the area of the holding device, can thereby be removed in an improved manner from the holding device, so that the flow of oil can pass very close to the area of contact, or even through the area of contact.

The opening may also lie outside of the area of contact. Wear on the bow spring, which can be caused by a section of the spring sweeping over the opening, is thereby prevented.

Preferably, the opening is offset axially outward from the radial vertex of the holding device. The area of contact can thereby include the vertex, and thus provide for good radial bracing of the bow spring, while at the same time the opening is not swept over directly by sections of the bow spring. Additional wear due to sweeping over the boundaries of the cutout can thereby be prevented.

In one embodiment, the holding device is formed in a flat material of the flange, and the opening is formed by a lift flap in the flat material. The lift flap can be easy to produce, and in particular subsequent to a known fabrication of the flange with the holding device, for example from a piece of sheet metal.

In a preferred embodiment, the lift flap is formed in a radial connecting section of the flange and is opened radially toward the inside, in order to let oil pass through that is flowing radially outward at the surface of the connecting section. This enables the flow of oil to be initiated in the area of contact without requiring an active supply of fresh oil, for example by means of a device for spraying the flange with oil.

The object of the invention is to specify a torsional vibration damper that has an extended service life.

The object is fulfilled by a torsional vibration damper having the features of the independent claim. Subordinate claims describe preferred embodiments.

These and other objects and advantages of the present invention will be readily appreciable from the following description of preferred embodiments of the invention and from the accompanying drawings and claims.

DETAILED DESCRIPTION OF THE INVENTION

At the outset, it should be appreciated that like drawing numbers on different drawing views identify identical, or functionally similar, structural elements of the invention. While the present invention is described with respect to what is presently considered to be the preferred aspects, it is to be understood that the invention as claimed is not limited to the disclosed aspect. The present invention is intended to include various modifications and equivalent arrangements within the spirit and scope of the appended claims.

Adverting now to the Figures,FIG. 1shows torsional vibration damper100for operating in an oil bath (“wet-running”), preferably in a drivetrain of a motor vehicle.

Torsional vibration damper100comprises input flange105, output flange110positioned coaxially thereto (shown only schematically), and a number of bow springs115that are situated on a circumference around the axis of rotation of flanges105and110. Here, each bow spring115is realized as a coaxial system of two bow springs.

Each bow spring115is in contact in an axial direction with two first contact elements120, which are rigidly connected to input flange105. In a corresponding manner, the ends of each bow spring115are also in contact with second contact elements125, which are rigidly connected to output flange110. Here, contact elements120and125are shaped so that a collision-free rotation of input flange105relative to output flange110is possible. During the rotation, no matter which direction, all of bow springs115are compressed.

Output flange119may also be an intermediate flange, which acts on an actual output flange through an arrangement of compression springs or some other vibration-damping transmission device. In this case, the depicted torsional vibration damper100is part of a serial torsional vibration damper. Other embodiments based on the depicted torsional vibration damper are likewise possible, for example having springs connected in parallel and/or using a centrifugal force pendulum or a dual mass flywheel.

In the depiction inFIG. 1, input flange105is connected to internal clutch basket130. Through internal clutch basket130, a torque can be introduced into torsional vibration damper100, which is conveyed elastically to output flange110while absorbing torsional vibrations. In other embodiments, torque can also be introduced into input flange105in a different way, for example by means of a hub, a sprocket or gearing. Output flange110is usually set up for passing the conveyed torque to a transmission, for example by means of a hub having gear teeth.

Input flange105is designed as a so-called retainer; that is, it is formed essentially like a flat pot or a bowl, in order to surround bow springs115on one radial outer side. The section of input flange105which leads past bow springs115radially on the outside is therefore designated hereinafter as holding device135. In an embodiment, holding device135can also be formed on output flange110.

On one radial outer side of holding device135, where input flange105extends farthest from the axis of rotation, a number of openings140are made in holding device135. Openings140are distributed evenly around a circumference and have an elongated shape which extends in the circumferential direction, with rounded edges. Oil that is present in area of contact145of bow spring115with holding device135can absorb abrasion particles that occur due to rubbing of bow spring115on holding device135. The abrasion particles may be present in the form of a fine metallic dust. As a result of centrifugal forces, the oil is pressed farther radially outward, and leaves torsional vibration damper100through one of openings140. The oil in the area of torsional vibration damper100can be circulated by means of an external circulating pump, the oil being pressed through a filter that removes the abrasion particles from the oil.

FIG. 2shows an embodiment of torsional vibration damper200. Openings240are again arranged along a circumference around the axis of rotation of torsional vibration damper200; in contrast to the embodiment depicted inFIG. 1, however, openings240are not made in input flange105at the outermost circumference, but radially farther inward, which simultaneously means an axial shift on the surface of the bulging holding device135. The shift occurs in the direction of the closed surface of input flange105, toward the left in the depiction inFIG. 2. A shift in the other direction is likewise possible.

The embodiment depicted inFIG. 2arranges openings240outside of area of contact145of bow spring215with input flange105. As a result, coils of bow spring215do not have to run past boundaries of openings240during compression or decompression.

FIG. 3shows a sectional view of torsional vibration damper200ofFIG. 2. The sectional plane runs through the axis of rotation of torsional vibration damper200

Vertex160of input flange105is a point on the input flange at the greatest distance from the axis of rotation of torsional vibration damper100. It is possible to recognize the manner in which opening240is displaced both radially and axially from vertex160of input flange105. Opening240is outside of contact area145. Line L1, parallel to axis of rotation AR, passes through opening240and bow spring215.

FIG. 4shows a sectional view of torsional vibration damper300. The sectional plane encloses an acute angle with the axis of rotation.

In the depicted embodiment, opening340is realized by lift flap150in input flange105. Input flange105is made from sheet metal, for example by deep drawing or pressing.

Lift flap150can be produced by making a U-shaped cut or a punching in the sheet metal of input flange105, followed by bending out the resulting tongue. The cut or punching may also be made before a metal sheet is formed into input flange105. When the sheet metal is later shaped into input flange105, the tongue is deformed less than a surrounding area, resulting in the depicted lift flap150. Line L2, orthogonal to axis AR, passes through opening340and flap150.

The open side of lift flap150points in the direction of connecting section155of input flange105that runs radially inward. Oil that collects, for example, due to splashing on the surface of connecting section155migrates outward on the surface of connecting section155as torsional vibration damper300rotates, due to centrifugal force. Oil flowing along on the left side of input flange105can pass through an opening340in the lift flap and flow to the area of contact145. Due to the constant inflow of oil into contact area145, its storage capacity is exhausted at some time, so that part of the stored oil is removed again from contact area145through one of openings340or in the area of the upper right boundary of input flange105inFIG. 4. The abrasion particles from bow spring315or from input flange105can be removed in this way from contact area145by means of the oil, so that the formation of a polishing layer or grinding paste based on the abrasion particles is prevented.

FIG. 5shows another view of torsional vibration damper300fromFIG. 4. For better understanding, only input flange105is shown, without bow springs315and output flange110. At lift flaps150which form the openings340, the U-shaped separating lines, cuts or stampings in the material of input flange105are clearly recognizable.

FIG. 6shows input flange105fromFIG. 5in a different perspective. In addition to openings340formed by lift flaps150, an additional opening340is made in holding device135of input flange105. The additional opening340is located opposite lift flaps150relative to the vertex, so that it is not made in the area of connecting section155, but rather in the area of the edge of input flange105shown at the upper right inFIG. 4.

The additional opening340enables an improved flow of oil out of holding device135, while lift flaps150transport oil in an improved manner into holding device135or contact area145.

LIST OF REFERENCE NUMBERS

120first contact element

125second contact element

AR axis of rotation

Ll line parallel to axis of rotation

L2line orthogonal to axis of rotation