EP1623140A1

EP1623140A1 - Balancing shaft for an internal combustion engine and method for the production thereof

Info

Publication number: EP1623140A1
Application number: EP04730235A
Authority: EP
Inventors: Torsten Harms; Frank Rohwer
Original assignee: DaimlerChrysler AG
Current assignee: Mercedes Benz Group AG
Priority date: 2003-05-09
Filing date: 2004-04-29
Publication date: 2006-02-08
Also published as: US20070251489A1; WO2004099648A1; DE10320747A1; DE10320747B4; US7533646B2

Abstract

The invention relates to a balancing shaft (1) for an internal combusting engine and to a method for producing said balancing shaft which consists of a tubular hollow body (2) and comprises a counterweight (5) and functional elements arranged on said hollow body. The aim of said invention is to produce a small-sized balancing shaft in a simplest possible manner, a necessary counterweight being arranged, if necessary, on an appropriate area. For this purpose, said counterweight is arranged on the external periphery (4) of the hollow body and fixed to said area.

Description

DaimlerChrysler AG

Balance shaft for an internal combustion engine and a method for producing the same

The invention relates to a balance shaft for an internal combustion engine according to the preamble of claim 1 and a method for producing the same according to the preamble of claim 8.

A generic balance shaft or a generic method for their preparation is known from DE 198 32 987 AI. The balance shaft described therein is tubular and has in its interior a balance weight which extends over almost its entire length. The tube part is provided on the circumference with two recesses, each having a centrally located hole. Each hole is penetrated by a pin that equally protrudes through the balance weight. The pin is used to attach the balance weight on the pipe part. The tube part is closed at both ends by a cover by means of pressing or soldering. In the described balance shaft, the attachment is very cumbersome because the pin must be countered either from the inside of the balance shaft or, if the pin is already located in the balance weight, the balance weight cumbersome to be pushed back and forth until the pin through the hole threaded in the pipe part wall and then countered from the outside can be. Furthermore, the practical requirements for a balance shaft are rarely as they can be seen from the known document. In most cases, the local arrangement of the balance weight is desired. In order to fulfill its function, the balance weight must have a certain size. However, the bigger this has to be, the more volume will be required by the balance weight. In order to achieve this in the known balancing shaft, the diameter of the pipe part with the increase of the local space load of the balance weight must increase in a corresponding manner. The result of this is that such a balancing shaft takes up so much space as it is usually not available today in modern engines.

The invention has the object of developing a generic balance shaft to the effect that a space-saving design of the shaft is made possible, which has a sufficient balance weight as needed at the desired location of the balance shaft. By the same token, it is a further object of the invention to provide a method with which the balance shaft can be produced in the simplest possible way.

The object is achieved by the features of claim 1 with respect to the balance shaft and by the features of claim 8 with respect to the method.

Due to the fact that according to the invention the balance weight is arranged and fastened on the outer circumference of the hollow body, the hollow body forming the base part of the balance shaft can be machined. Its diameter is relatively small and the wall thickness very low (about 2mm) are designed, resulting in a significant reduction in weight of the entire shaft. Of the way The inner length of the hollow body is not increased by the local placement of the balance weight on the outer circumference, so that overall the space required for the hollow body is particularly low and only space instead of the placement of the balance weight must be provided in the engine sufficient space. In addition, the balance weight is readily accessible and placeable in a simple manner at the right place of the hollow body, wherein the axial position is also freely selectable for the functional elements, and can be fixed by any suitable means on the hollow body without much effort.

In a preferred embodiment of the invention according to claim 2, the balance weight is formed on a hub which surrounds the hollow body locally and is secured thereto. Through the hub, only a small space is claimed while it offers a larger connection surface for attachment to the hollow body for the balance weight by the enclosure of the hollow body, so that an overall improved grip of the balance weight is achieved on the hollow body.

In a further preferred embodiment of the inventive balancing shaft according to claim 3 or the corresponding inventive method according to claim 10, the balancing weight is connected in an interference fit with the hollow body. The interference fit a secure attachment of the balance weight is achieved with relatively simple means, without additional fasteners. For achieving such a press fit, for example, thermal shrinking or magnetic forming as well as the pressing-on of the balance weight with an inner diameter of the hub having an undersize relative to the outer diameter of the hollow body are conceivable. In a further preferred embodiment of the invention, the functional elements are arranged according to claim 4 with respect to the balance shaft and the claim 11 with respect to the corresponding method as individual components on the hollow body and connected to this in a press fit. Here, the same advantages as in the embodiment according to claim 3 and 10 can be mentioned.

In a particularly preferred embodiment of the balance shaft according to the invention according to claim 5, the balance weight and / or the functional elements are additionally positively connected to the hollow body. This leads to a further improved hold of the balance weight and the functional elements on the hollow body against mechanical loads in the axial or radial direction.

In a further, particularly preferred embodiment of the balance shaft according to the invention according to claim 6, the hollow body at the point of its connection with the balance weight is widened plastically, wherein the balance weight is widened elastic spring-back at this point. This results in a particularly strong press connection between the hollow body and balance weight for an immovable hold the balance weight at axial and very high radial mechanical stresses, especially at high speed of the balance shaft and high masses of the balance weight during operation of the balance shaft.

A further preferred embodiment of the balance shaft according to the invention shows claim 7. Here, the hollow body is integrally connected at one end with a connection component for drive components, such as sprockets or centrifuges, wherein the connection component closes the hollow body. Due to the integral nature of the connection results in a high strength for the entire component of the balance shaft at the junction. At the same time, the balance shaft is closed at one end by this connection, after which it only needs to be closed after at the opposite end. This is done, for example, with a lid, which prevents total, that enters the interior of the hollow body moisture, which can lead to corrosion of the balancer shaft. The integral nature of the connection and the massiveness of the connection component, the balance shaft on a high stability against the engagement of the drive components.

In a preferred embodiment of the inventive method according to claim 9, the balance weight is pushed by means of a hub on which it is formed on the hollow body and then attached thereto. By pushing a simple positioning of the balance weight is achieved on the hollow body, which is required for subsequent fixation on the hollow body only a small amount of equipment for holding or clamping, since the hollow body already carries the balance weight after pushing.

A further, particularly preferred embodiment of the method according to the invention represents claim 12. By using a fluidic internal high pressure to achieve the interference fit, the positioning of the balance weight and / or the functional elements is further facilitated as a postponement of the balance weight and / or the functional elements with excess of the hub inner diameter or the bore diameter is particularly smooth. In addition, by means of the fluid pressure control of the internal high pressure, the desired press assembly precisely adjustable, because in its manufacture advantageously by a suitable pressure control, the wall thickness and the material properties of the joining partners can be considered in terms of breaking strength, so that in the production of the balance shaft, the process reliability is absolutely guaranteed. Furthermore, the joining process can be done quickly and with relatively little equipment.

In a further, particularly preferred embodiment of the inventive method according to claim 13, the wall of the passage opening of the hub and / or the wall of the bore, with the balance weight and / or the functional elements are pushed onto the hollow body, formed non-rotationally symmetrical, by means of fluidic internal high pressure of the hollow body, by at least partially conditioning non-rotationally symmetrical surfaces of the wall of the passage opening of the hub and / or the wall of the bore, is positively connected to the balance weight and / or the functional elements. By forming the inside of the hub or the bore in non-rotationally symmetrical form, for example in oval design or formed by depressions or longitudinal grooves in the production or by subsequent processing, is in interaction with the internal high pressure, which can flow the hollow body material and this the non-rotationally symmetric surfaces of the bore wall or the wall of the hub passage opening, where it remains irreversible, forcibly achieves a positive fit. This positive engagement even further increases the strong hold of the joining partners achieved by the frictional engagement of the pressed composite of hollow body and compensating weight and / or functional elements. In a further embodiment of the method according to the invention, at least one of the open ends of the hollow body is friction-welded to a connecting component closing the end for drive components, such as sprockets or centrifuges. Through the use of friction welding, a very durable connection of the hollow body to the attachment component is created with a low cycle time and relatively little effort.

The invention is explained in more detail with reference to several embodiments shown in the drawings; showing:

1 shows a longitudinal section of a balance shaft according to the invention with a connection component,

2 shows a front view of a balance weight for a balancing shaft according to the invention according to FIG. 1,

Fig. 3 in a longitudinal section in sections a balance shaft according to the invention with stored on her functional elements.

In Figure 1, a balancer shaft 1 is shown for an internal combustion engine, wherein the shaft 1 consists of a rohrformigen hollow body 2, which in turn consists of a pipe section of a drawn tube. However, the hollow body 2 can also be made from a rolled board, which is longitudinally welded at its impact. At one end 3 of the balance shaft 1, a balance weight 5 is disposed on the outer periphery 4 of the hollow body 2 and _. fixed there. Towards the other end 6 of the balance shaft 1, the hollow body 2 carries a functional element in the form of a bearing sleeve 7, which is supported at one end on an end face 8 of the balance weight 5. The balancing weight remote end 9 of the hollow body 2 is integrally connected to a connection member 10. The attachment component 10, which is solid, forms a continuation of the axial extension of the hollow body 2. The attachment component 10, which may be a rotary part, a hot press, a sintered or a cold extrusion part, serves for connection to drive components, such as sprockets or centrifuges ,

To produce the balance shaft 1, first the bearing sleeve 7 and then the balance weight 5 is pushed to the desired position. While this is accomplished via the bore 11 of the bearing sleeve 7, the balance weight 5 is formed on a hub 12, as also illustrated in Figure 2, so that the balance weight 5 with the through hole 13 of the hub 12 is pushed onto the hollow body 2. Subsequently, the bearing sleeve 7 and the balance weight 5 is connected to the hollow body 2 to form a press fit. The bearing sleeve 7 and the balance weight 5 can be connected to each other separately or simultaneously with each other with the hollow body 2. The generation of the interference fit can be done for example by broaching the hollow body 2. Here, however, advantageously the joining process by means of fluidic internal high pressure, which is generated in the interior of the hollow body 2, are performed. For the internal high pressure joining several techniques are conceivable. For example, the hollow body 2 can be inserted with the deferred bearing sleeve 7 and the deferred balance weight 5 in an internal high pressure forming die, wherein the die outside the joints to be generated has the negative contour of the balance shaft 1. At the location of the slipped joining parts, ie the bearing sleeve 7 and the balance weight 5, the die is formed such that the joining parts are stored there with a predetermined game. Finally, a fluidic internal high pressure is generated in the entire hollow body 2, which plastically diffuses the hollow body 2 only at the joints. tet, during which there is no uncontrolled deformation of the hollow body 2 outside of the joints by the system of the hollow body 2 at the engraving of the forming die. The outer circumference 4 of the hollow body 2 settles by the plastic expansion of the hollow body 2 on the wall of the passage opening 13 of the hub, as well as at the same time on the bore wall of the bearing sleeve 7. The hollow body 2 is now further expanded at short notice, thereby over its respective Appendix the bearing sleeve 7 and the balance weight 5 and the hub 12 is widened plastic. After relaxing the pressure fluid within the hollow body 2, the material of the bearing sleeve 7 and the hub 12 or the balance weight 5 springs back, during which the hollow body 2 remains in its expanded plastic formation. This creates an extremely high press fit. Another conceivable possibility of using the hydroforming technique is that two movable punch are retracted respectively in the left and the right end of the hollow body 2 until they occupy a fixed axial distance from each other. By this distance, a gap is limited, which comes to rest in Fügelage below the parts to be joined. Subsequently, pressure fluid is introduced into the intermediate space via one of the punches or both punches and generates a high pressure. By means of this high pressure, the hollow body 2 is widened plastically only at the location of the parts to be joined. Another, particularly advantageous variant of the internal high-pressure technology consists in the insertion of a Aufweitlanze in the hollow body 2, wherein within the expansion lance an axial pressure fluid channel extends from which radial short channels, or it is also the branch of only a single channel conceivable depart and on the outer jacket of the expansion lance. The mouth openings are axially bounded laterally by ring seals and include an expansion space. When inserting the Aufweitlanze in the hollow body 2 nestle the ring seals on the inside of the hollow body 2 at. After reaching a desired insertion length, the respective expansion space is below the joint of the respective joining part. Then, the expansion of the hollow body 2 can be carried out by introducing a pressurized fluid through the mentioned channels. In the arrangement of several Aufweiträumen the joining parts can be added simultaneously or be added in the arrangement of only one expansion space sequentially with the hollow body 2. The latter variant of the internal high-pressure technology requires only small equipment expense and allows a particularly fast production of the balancer shaft 1. Then the hollow body 2 fitted with the bearing sleeve 7 and the balance weight 5 is friction-welded at its end 9 to the connection component 10, whereby between this and the hollow body a one-piece connection arises. Alternatively, however, it is also conceivable to connect the hollow body 2 without the joining parts in a first working step with the connecting component 10, after which the joining with the joining parts according to the first and third variants of the hydroforming technique can proceed ,

An additional increase in the hold of the parts to be joined, in particular the balance weight 5 on the hollow body 2, and thus the reliability of the balance shaft 1 can be achieved by the formation of a positive connection. For this purpose, 12 axially extending grooves 14 are formed on the wall of the otherwise circular cylindrical passage opening 13 of the hub, which constitute nichtrotationssymmetrische surfaces of the passage opening 13. Now that the balance weight 5 has been pushed with the hollow body 2 locally enclosing hub 12 on the hollow body 2 and positioned accordingly, a fluidic internal high pressure is generated - as usual - which expands the hollow body 2 plastically. It will the hollow body material displaced into the grooves 14, where it at least partially finds a plant and digs into the grooves 14. The desired fit is thus achieved. Such a trained positive connection is also conceivable in each of the deferred functional elements. By increasing the hold of the balance weight 5 and the functional elements on the hollow body 2 via the positive locking can be saved on other labor-intensive haltfördernde processing such as a backlash the wall of the through hole 13 of the hub 12 and the wall of the bore 11 of the functional elements.

To round it off, reference is made here to FIG. 3, in which a tubular hollow body 2 is shown, onto which a balance weight 5 with its hub 12 a bearing sleeve 7 and a sprocket 15 are pushed with play and finally joined with internal high pressure. Likewise, sensor rings on the hollow body 2 can be joined.

Claims

DaimlerChrysler AGPatent claims

1. balancing shaft for an internal combustion engine, which consists of a rohrformigen hollow body, and a balancing weight and arranged on the hollow body functional elements, d a d u r c h e c e n e s in that the balancing weight (5) on the outer circumference (4) of

Hollow body (2) is arranged and fixed.

2. balancing shaft according to claim 1, d a d u r c h e g e k e n e e c e in that the balance weight (5) on a hub (12) is formed, which surrounds the hollow body (2) locally and is fixed thereto.

3. balancing shaft according to one of claims 1 or 2, d a d u r c h e c e n e z e h e in that the balance weight (5) in an interference fit with the hollow body (2) is connected.

4. balance shaft according to one of claims 1 to 3, characterized in that the functional elements arranged as individual components on the hollow body (2) and with this in one Press fit are connected.

5. balancing shaft according to one of claims 1 to 4, d a d u r c h e c e n e z e i c h e s that the balance weight (5) and / or the functional elements are additionally positively connected to the hollow body (2).

6. balancing shaft according to one of claims 3 to 5, d a d u r c h e c e n e c e s that the hollow body (2) at the point of its connection with the balance weight (5) is plastically expanded, and that the balance weight (5) is expanded resiliently spring-back at this point.

7. balancing shaft according to one of claims 1 to 6, d a d u r c h e c e n e c e in that the hollow body (2) at one end with a connection component (10) for drive components such as sprockets or centrifuges is integrally connected, wherein the connection member (10) closes the hollow body (2).

8. A method for producing a balance shaft, wherein a balance weight and functional elements are attached to a rohrformigen hollow body, d a d u r c h e c e n e s in that the balance weight (5) on the outer circumference (4) of the hollow body (2) is positioned and fixed there.

9. The method according to claim 8, characterized in that the balance weight (5) by means of a hub (12) on which it is formed, pushed onto the hollow body (2) and then attached.

10. The method of claim 8, wherein the balancing weight positioned on the hollow body is connected to the hollow body in order to form an interference fit.

11. The method according to claim 8, wherein the functional elements are pushed as individual components onto the hollow body (2) with a bore (11) and subsequently connected to it to form a press fit.

12. The method according to any one of claims 10 or 11, characterized in that the interference fit is formed by partial expansion of the hollow body (2) by fluidic internal high pressure, wherein the hollow body (2) at the location of the deferred balance weight (5) and / or the functional elements locally plastic and the balance weight (5) and / or the functional elements are resiliently rebounding expanded.

13. The method according to claim 12, characterized in that the wall of the passage opening (13) of the hub (12) and / or the wall of the bore (11) with which the balance weight (5) and / or the functional elements on the hollow body (2 ), is formed non-rotationally symmetrical, and that by means of fluidic internal high pressure of the hollow body (2) by at least partially investing in non-rotational rotationally symmetrical surfaces of the wall of the passage opening (13) of the hub (12) and / or the wall of the bore (11) with the balance weight (5) and / or the functional elements is positively connected.

14. The method according to claim 8, wherein at least one of the open ends of the hollow body is friction-welded to a connecting component closing the end for drive components such as sprockets or centrifuges.