DE102012210171A1 - balancer shaft - Google Patents

Abstract

Proposed is a balance shaft (1) to compensate for inertial forces and / or moments of inertia of an internal combustion engine, comprising a support shaft (2) with a non-rotationally symmetrical profiled outer cross section (11) and one or more shaft parts (3, 5, 8, 9) each threaded with an outer cross-section substantially complementary profiled inner cross section (12) on the support shaft and are fixed. In this case, the outer cross-section and inner cross-sectional profiles should be dimensioned so that an intermediate gap is formed, wherein the shaft parts are fixed by means of an injected into the gap intermediate layer (13) made of plastic on the support shaft.

Description

The invention relates to a balance shaft for balancing mass forces and / or moments of inertia of an internal combustion engine. The balancer shaft comprises a carrier shaft with a non-rotationally symmetrically profiled outer cross section and one or more shaft parts, which are each threaded and fixed on the carrier shaft with an inner cross section profiled in an essentially complementary manner to the outer cross section.

Background of the invention

A built-up of parts balance shaft in which the carrier shaft and shaft parts that form the imbalance and the bearing points of the balancer shaft, manufactured as individual parts and then assembled, goes out of the generic JP 2000186746 A out. The assembly is carried out by rotationally threading, ie axial sliding of the shaft parts on the support shaft with radial fixation and positively predetermined angular alignment of the imbalance parts on the circumference of the carrier shaft. The positive rotation is generated by the non-rotationally symmetrical and partially or completely complementary cross-sectional profiles of the carrier shaft and the shaft parts. For axial attachment, the shaft parts are soldered to the carrier shaft.

A disadvantage of this wave design is the high accuracy of fit of the mutually complementary components, which is always associated with structurally disadvantageous double fits between the carrier shaft and the shaft parts.

Object of the invention

The present invention has for its object to simplify constructively a built balancer shaft of the type mentioned and in particular to make so that the balancer shaft is possible produce double-free as possible.

Summary of the invention

The solution of this problem arises from the characterizing features of claim 1, while advantageous developments and refinements of the invention are the dependent claims can be removed. Accordingly, the Außenquerschnitts- and inner cross-sectional profiles should be dimensioned so that a gap extending therebetween is formed, wherein the shaft parts are fixed by means of an injected into the gap intermediate layer of plastic on the support shaft.

Unlike in the cited prior art, therefore, a very large and consequently double-pass free radial clearance between the carrier shaft and the shaft parts is provided. The gap thus formed is sprayed after the threading and positioning of the shaft parts on the support shaft in a plastic injection molding machine with plastic, whereby the shaft parts are permanently attached to the support shaft. In the circumferential direction, the attachment is mainly due to the positive connection between the non-rotationally symmetrical cross-sectional profiles in conjunction with the interposed, filled with plastic gap. The shaft parts are preferably positioned on the carrier shaft so that the gap and consequently the plastic intermediate layer has a substantially uniform wall thickness. With regard to the process-safe plastic injection molding, this is expediently in the order of 2 mm.

In the longitudinal direction of the balance shaft, the attachment is effected both by the cohesive surface adhesion of the shaft parts and the carrier shaft on the plastic. In addition, a positive fit that is effective in the longitudinal direction can be produced by providing the carrier shaft and / or the shaft parts with local recesses or openings that are encapsulated with the plastic. This should be a polyamide 66, preferably with glass fiber reinforcement.

The shaft parts may comprise one or more unbalance parts with eccentric center of gravity to the shaft axis and one or more bearing parts for rolling bearing of the balance shaft. Only the bearing parts should consist of a bearing steel, while the unbalance parts are made of other materials. The background for this advantageous material mix is the currently increasing use of directly needle-bearing balance shafts whose bearing points are the inner races of needle bearings. While the bearing parts consisting of rolling bearing steel have the material structure required for the rolling resistance, the unbalance parts can be produced significantly more cost-effectively and be designed, for example, as sheet-metal stamped parts stacked on one another or as cast steel parts. The sheet metal stampings can be threaded individually or as a preassembled unit on the support shaft, wherein the assembly by means of the known Stanzpaketier method can be produced. The bearing steel grades C16, 16MnCr5, C45, Cf53, C80 and 100Cr6 are considered.

Brief description of the drawings

Further features of the invention will become apparent from the following description and from the drawings, in which an embodiment of a balance shaft according to the invention is shown. The same or functionally identical components are provided with the same reference numbers. Show it:

1 the balance shaft in perspective overall view;

2 the balance shaft in plan view;

3 the balance shaft in longitudinal section;

4 the cross section AA according to 2 and

5 the cross section BB according to 2 ,

Detailed description of the drawings

The 1 to 3 show different views of a balance shaft 1 to compensate for free inertial forces of the second order of an internal combustion engine in four-cylinder in-line construction. In this known as Lancaster compensation balancing two balance shafts rotate 1 with double crankshaft speed in opposite directions.

• – ein Antriebsteil 3 aus Stahlguss, das mit einem die Ausgleichswelle 1 drehend antreibenden (nicht dargestellten) Antriebsrad verbunden ist und mit einem Lagersitz 4 für ein (ebenfalls nicht dargestelltes) Schrägkugellager versehen ist.
• – zwei Lagerteile 5 aus Wälzlagerstahl 100Cr6, die jeweils eine radial zurückspringende Innenlaufbahn 6 für ein (nicht dargestelltes) Radialnadellager aufweisen. Die als Gleichteile ausgeführten Lagerteile 5 umfassen im dargestellten Ausführungsbeispiel jeweils eine innen eingespritzte Kunststoffbuchse 7, die axial beidseitig der Innenlaufbahn 6 übersteht (siehe auch 4).
• – an die Lagerteile 5 angrenzende Unwuchtteile, nämlich zu Paketen 8 zusammengefasste Blechstanzteile und Gussteile 9.

The balance shaft 1 is made up of individual components, namely a carrier shaft 2 and shaft parts attached thereto. The carrier wave 2 is a cut extruded profile rod made of steel material. The shaft parts include:

• - A drive part 3 made of cast steel, with a balance shaft 1 rotationally driving (not shown) driving wheel is connected and with a bearing seat 4 is provided for a (also not shown) angular contact ball bearings.
• - two bearing parts 5 made of bearing steel 100Cr6, each with a radially recessed inner raceway 6 for a radial needle bearing (not shown). The bearing parts designed as identical parts 5 In the illustrated embodiment, each comprise an internally injected plastic bushing 7 axially on both sides of the inner race 6 survives (see also 4 ).
• - to the bearing parts 5 adjacent unbalance parts, namely to parcels 8th combined sheet metal stampings and castings 9 ,

The T-shaped profiled carrier shaft 2 and all shaft parts 3 . 5 . 8th . 9 point to the shaft axis 10 and in the same orientation eccentric centers of mass and thus contribute together to the wave imbalance of the balancer shaft 1 at.

The carrier wave 2 has a non-rotationally symmetrical, here T-shaped profiled outer cross-section 11 on, and all wave parts 3 . 5 . 8th . 9 are with an essentially complementary profiled inner cross-section 12 on the carrier shaft 2 threaded. The outer cross section profile 11 the carrier wave 2 and the inner cross-sectional profile 12 the bearing parts 5 and the drive part 3 is from their sectional views in the 4 respectively. 5 seen. There it becomes clear that the outer cross section profile 11 the carrier wave 2 dimensionally much smaller dimensioned than the inner cross-sectional profile 12 the shaft parts 3 . 5 . 8th . 9 and that consequently an intervening gap is formed. The gap has considerable manufacturing advantages, since on the one hand producible only with great effort fit the T-shaped cross-sectional profiles 11 . 12 and on the other hand also a double fit is omitted, which in such a fit to form and position errors on the circumference of the shaft parts 3 . 5 . 8th . 9 would lead.

The attachment of in this way with great radial play on the carrier shaft 2 threaded shaft parts 3 . 5 . 8th . 9 takes place in a plastic injection molding machine, in which the shaft parts 3 . 5 . 8th . 9 axially and radially on the carrier shaft 2 be aligned and in the gap an intermediate layer 13 made of plastic, here PA66GF25 (reinforced polyamide with 25% glass fiber content), is injected and fills the gap. This also applies to the aforementioned bearing parts 5 with the previously injected plastic bush 7 , alternatively with a correspondingly reduced internal cross-sectional profile of the bearing parts 5 can also be omitted.

In the longitudinal direction of the balance shaft 1 becomes the cohesive bond of the carrier wave 2 and the shaft parts 3 . 5 . 8th . 9 with the plastic liner 13 supported by a form-fitting, which by local recesses in the form of plastic-molded notches 14 on the carrier shaft 2 is formed.

LIST OF REFERENCE NUMBERS

1

 balancer shaft

2

 carrier wave

3

 driving part

4

 Bearing seat on the drive part

5

 bearing part

6

 Inner raceway

7

 Plastic bushing

8th

 Stamped sheet metal package

9

 Unbalance Casting

10

 shaft axis

11

 External cross-sectional profile

12

 Internal cross-sectional profile

13

 Plastic Liner

14

 score

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• JP 2000186746 A [0002]

Claims (7)

Balance shaft ( 1 ) for balancing mass forces and / or mass moments of an internal combustion engine, comprising a carrier shaft ( 2 ) with a non-rotationally symmetrically profiled outer cross section ( 11 ) and one or more shaft parts ( 3 . 5 . 8th . 9 ), each with an outer cross section ( 11 ) substantially complementary profiled inner cross section ( 12 ) on the carrier shaft ( 2 ) are threaded and fastened, characterized in that the outer cross-section and inner cross-section profiles ( 11 . 12 ) are dimensioned so that an intermediate gap is formed, wherein the shaft parts ( 3 . 5 . 8th . 9 ) by means of an intermediate layer injected into the gap ( 13 ) made of plastic on the carrier shaft ( 2 ) are attached. Balance shaft ( 1 ) according to claim 1, characterized in that the plastic is a glass fiber reinforced polyamide. Balance shaft ( 1 ) according to claim 1, characterized in that the outer cross-sectional profile ( 11 ) of the carrier wave ( 2 ) is substantially T-shaped. Balance shaft ( 1 ) according to claim 1, characterized in that the carrier shaft ( 2 ) and / or the shaft parts ( 3 . 5 . 8th . 9 ) with local recesses ( 14 ) or openings are provided, which are encapsulated with the plastic. Balance shaft ( 1 ) according to claim 1, characterized in that the shaft parts ( 3 . 5 . 8th . 9 ) one or more imbalance parts ( 8th . 9 ) with the shaft axis ( 10 ) eccentric center of gravity and one or more bearing parts ( 5 ) for rolling bearing of the balance shaft ( 1 ), whereby only the bearing parts ( 5 ) consist of a bearing steel. Balance shaft ( 1 ) according to claim 5, characterized in that the unbalance parts ( 8th . 9 ) of stacked sheet metal stampings ( 8th ) or cast steel ( 9 ) consist. Balance shaft ( 1 ) according to claim 5, characterized in that the center of gravity of the imbalance parts ( 8th . 9 ), the bearing parts ( 5 ) and the carrier wave ( 2 ) are eccentric in the same orientation.

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