Patent Application
20240035555
The present disclosure relates to a drive wheel which has a drive disk comprising a traction-means connection region and a shaft connection region that can be rotated relative to the traction-means connection region against the damping action of at least one torsional vibration damping device, and a method for producing such a drive wheel.
European patent specification EP 1 612 386 B1 describes a drive wheel for driving an auxiliary assembly of an internal combustion engine of a vehicle having a damping device, wherein the drive wheel can be coupled to a shaft and the damping device comprises at least one torsional vibration damper which operates without grease or oil lubrication and has a damper cage for receiving at least one spring accumulator designed as a compressible spring. International publication WO2008/058499 A2 describes a drive wheel having at least one drive disk and having a torsional vibration damping device that includes bow springs that are arranged in a grease-filled spring chamber that is sealed with the aid of sealing lips that are formed on a plastic part.
When using a belt pulley decoupler with such a drive disk, a cylindrical interference fit is used to close off the internal space between the drive disk and a cover. Depending on the tightness requirement, the viscosity of the internal medium and the macro and micro geometry of the components, the operating speed and/or the ambient temperature, an additional medium/sealing means is required to ensure tightness.
Nevertheless, in the case of the solutions with conventional component dimensions and tolerances, the desired tightness cannot be guaranteed under all circumstances without sealing means. Even with solutions with sealing means on the surfaces, there is no guarantee that this sealing means will be distributed evenly over the circumference since it is only “taken along” by the inserted cover into the interference fit during the pushing-in process or pressing-in process. Likewise, there is no guarantee that the interior space after assembly, i.e., the spring accommodation chamber, will not be contaminated by residues that are pushed along on the front edge of the cover.
The present disclosure provides, according to an exemplary embodiment, a drive wheel, which is of simple construction and/or can be produced inexpensively and offers good tightness. Furthermore, present disclosure provides a method for producing such a drive wheel.
The drive wheel according to the present disclosure serves to decouple vibrations and can therefore also be referred to as a drive wheel decoupler or belt pulley decoupler. Springs, in particular bow springs, may be used to decouple the vibrations.
The solution to the problem consists, inter alia, in that the inner body of the cylindrical interference fit consisting of the drive disk and cover of a drive wheel is provided with a groove into which a sealing means can be metered before assembly. The groove may be arranged over the entire circumference. The opening of the groove faces the radially inner surface of the drive disk. At the end of the assembly process, the drive wheel is subjected to the influence of speed, which means that the sealing means is automatically distributed over the region to be sealed and ensures a secure seal in a defined region.
The drive wheel according to the present disclosure having a drive disk, which has a traction-means connection region, and a shaft connection region which can be rotated relative to the traction-means connection region against the damping action of at least one torsional vibration damping device, wherein a spring accommodation chamber filled with lubricant is closed by means of a cover, is distinguished in that the cover has a groove facing the drive disk, which cover contains a sealing means.
A traction means, for example a belt, can be coupled to the drive wheel via the traction-means connection region and used to transmit torque. The relative rotation of the traction-means connection region and the shaft connection region takes place about a common axis of rotation. The designations “axial” and “radial” used in this document always refer to this axis of rotation. The sealing means is contained in the groove and, in particular after assembly, rests radially on the outside in the groove and thus may be on the drive disk and optionally on the cover. Before the drive wheel is installed, the sealing means is introduced into the groove and may be located at the base of the groove. As a result, contamination of the sealing means or discharge of the sealing means into regions in which it would represent a contamination can be reliably avoided. At the same time, when the drive wheel is subjected to a rotational speed, the sealing means is pushed radially outwards and seals against the drive disk radially on the inside. In this way, a sealing means application that is uniform in the circumferential direction can be achieved.
According to an exemplary embodiment, the cover is press-fitted into the drive disk, so that an interference fit is formed between the cover and the drive disk. In particular, the formation of a cylindrical transverse interference fit allows the assembly and formation of a non-positive connection between the cover and the traction disk in a simple manner.
According to an exemplary embodiment, the cover is mounted on a support body in the radial direction. This enables a simple construction of the drive wheel.
According to an exemplary embodiment, the cover is manufactured from sheet metal without machining, solely by means of forming. In this way, a simple production of the cover can be achieved. In particular, the groove can be produced without further processing steps. According to an exemplary embodiment, the cover remains unhardened after forming.
According to an exemplary embodiment, the sealing means is positioned radially on the outside in the groove. This is the case in particular after assembly, after the drive wheel with the introduced sealing means is set in rotation. Due to the applied centrifugal forces, the sealing means is pushed radially outwards and thus rests evenly on the drive wheel radially inwards.
According to an exemplary embodiment, an anaerobically hardened, in particular thixotropic sealing means is used as the sealing means. In this context, the use of a sealing means with a viscosity of 5,000 to 25,000 millipascal seconds, in particular 5,000 to 12,000 millipascal seconds, is preferred.
According to an exemplary embodiment, the drive disk and cover form an interference fit with a first contact region and a second contact region that are spaced apart from one another in the axial direction, wherein the groove is formed in the axial direction between the first contact region and the second contact region. Thus, the sealing means is also formed in the axial direction between the first contact region and the second contact region, so that displacement of the sealing means by rotation radially outward leads to both contact regions, which at the same time form the joints of the interference fit, being reliably sealed. In this way, the spring chamber of the drive wheel can be reliably sealed.
In this context, the sealing means may rest radially on the inside between the first contact region and the second contact region on the drive disk. The displacement of the sealing means by rotation thus may lead to the sealing means being displaced from a position radially on the outside of the cover, i.e., in the bottom of the groove, radially to the outside and resting there radially on the inside of the drive disk.
Furthermore, a method for manufacturing a drive wheel according to the present disclosure is proposed, having the following steps:
The introduction of the sealing means into the groove of the cover prior to the formation of the interference fit means that the sealing means can be metered well, which effectively prevents the sealing means from being distributed outside of the joints. Due to the rotational movement, the sealing means is displaced radially outwards and thus the formation of a seal between the joints of the sealing assembly is reliably achieved and possible irregularities in the metering of the sealing means over the circumference are compensated for under the influence of centrifugal force. The details and advantages disclosed for the drive wheel can be transferred and applied to the manufacturing process and vice versa.
As a precaution, it should be noted that the numerical designations used here (“first”, “second”, etc.) serve primarily (only) to distinguish between several similar objects, sizes, or processes, and in particular no necessary dependency and/or sequence of these objects, sizes, or processes to each other is indicated. If a dependency and/or sequence is necessary, this is explicitly stated here or results in a manner obvious to the person skilled in the art when studying the specifically described configuration.
Both the present disclosure and the technical field are explained in more detail below with reference to the figures. It should be noted that the present disclosure is not intended to be limited by the exemplary embodiments shown. In particular, unless explicitly stated otherwise, it is also possible to extract partial aspects of the subject matter outlined in the figures and to combine them with other components and knowledge from the present description and/or figures. In particular, it should be noted that the figures and in particular the size ratios shown are only schematic in nature. Identical reference symbols indicate the same objects, so that where applicable, explanations from other figures can also be used. In the figures:
The rotation of the drive wheel 1 takes place about a rotation axis 11. The drive disk 3 comprises a traction-means connection region 5 to which a traction means, not shown, such as a belt can be frictionally applied to transmit torque between the drive wheel 1 and the traction means. The drive wheel 1 also has a shaft connection region 8, via which the drive wheel 1 can be connected to a shaft, in particular a crankshaft of an internal combustion engine. In this way, torque can be transmitted in both directions between the internal combustion engine and an electrical assembly, such as an alternator or a starter generator, which is connected via the traction-means connection region 5 and a corresponding traction means.
Shaft connection region 8 and traction-means connection region 5 can be rotated relative to one another against a torsional vibration damping device 10. In this example, the torsional vibration damping device 10 comprises multiple springs 31, in particular bow springs, which are formed in a spring accommodation chamber 38 which is filled with a lubrication medium. In the example known from the prior art, the sealing essentially takes place via the first contact region A and the second contact region B. The first contact region A and the second contact region B are formed during press joining. It may be possible to specify the exact position of the first contact region A and/or the second contact region B through a rotary contour raised in this region during the manufacture of the interference fit.
After the assembly process, the component is brought under the influence of speed. As a result, the sealing means 100 is conveyed outwards in the direction of centrifugal force and is placed in the interference fit to be sealed between the first contact region A and the second contact region B, and thus ensures the required sealing action. This is depicted in
By means of the described design of the drive wheel 1 and the assembly manufacturing method, the sealing means 100 is introduced into the appropriate region without the sealing means 100 getting outside of the interference fit. The sealing means 100 is then neither visible from the outside nor does it protrude into the spring accommodation chamber 38.
By introducing the groove 50 during the stamping/forming process, it is possible to carry out the interference fit without lathe machining of the cover 34/inner part, and to ensure the necessary tightness due to the additional sealing means 100.
| Number | Date | Country | Kind |
|---|---|---|---|
| 10 2020 131 624.0 | Nov 2020 | DE | national |
| 10 2021 104 889.3 | Mar 2021 | DE | national |
This application is the U.S. National Phase of PCT Appln. No. PCT/DE2021/100839 filed Oct. 18, 2021, which claims priority to DE 102021104889.3 filed Mar. 1, 2020, which in turn claims priority to DE 102020131624.0 filed Nov. 30, 2020, the entire disclosures of which are incorporated by reference herein.
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/DE2021/100839 | 10/18/2021 | WO |
