Balance shaft and manufacturing method thereof

Abstract

The invention relates to a balance shaft (1) and to a method for producing a balance shaft. The balance shaft comprises an unbalanced shaft (2) having a bearing neck (7) and a bearing ring (12) fitted on the bearing neck, the inner side (15) of which is in contact with the bearing neck at its inner diameter Di-LR, the bearing neck having a relationship dHlt; the invention relates to a method for measuring the outer diameter dH of the envelope circle of the unbalanced shaft (1), Di-LR, comprising the following steps: i) aligning the unbalanced shaft with a shaft reference (17) such that a shaft reference point (18, 19) of the unbalanced shaft has a predetermined distance (20, 21) from the shaft reference; ii) measuring or checking a distance (22) between a shaft balance point (23) on the bearing neck and the shaft reference; iii) selecting the bearing rings from group classifications as a function of the measured or checked distance, the groups (G1, G2, G3) of the group classifications being classified as a function of mutually different inner diameters Di-LR of the bearing rings; and iv) assembling the bearing ring on the bearing neck.

Description

[0001] The present invention relates to a method for manufacturing a balancing shaft, wherein the balancing shaft comprises an unbalanced shaft having a bearing journal and a bearing ring mounted on the bearing journal, wherein the inner side of the bearing ring has an inner diameter D i-LR The bearing journal is in contact with the bearing journal, where the bearing journal has a relationship d H <D i-LR The outer diameter d of the envelope circle H The present invention also relates to a balancing shaft manufactured by the method.

[0002] Such balancing shafts are used in internal combustion engines to compensate for the free mass forces and / or moments from the crank mechanism. Modern balancing shafts typically use radial needle bearings to reduce friction, wherein the inner raceway of the needle bearing is formed by a bearing ring mounted on the bearing journal of the unbalanced shaft. Bearing journals with a non-circular cross-section oriented radially in the direction of the imbalance also lead to shaft imbalance, so that for a given imbalance, the mass of the unbalanced shaft can be relatively small. The favorable (i.e. large) unbalanced mass ratio is particularly due to the fact that the outer diameter of the envelope circle of the bearing journal is smaller than the inner diameter of the inner side of the bearing ring that contacts the bearing journal. In this case, it is naturally impossible to fasten the bearing ring to the bearing journal by means of a conventional transverse or longitudinal interference fit. In this regard, DE 10 2016 210 480 A1 discloses fastening the bearing ring by means of a spring element, which is clamped in the free space between the bearing ring and the bearing journal.

[0003] DE 10 2005 047 950 A1 discloses the dimensional adaptation of a rolling bearing which is located in a radial installation space between a housing and a shaft rotatably mounted in the housing in order to maintain a predetermined bearing clearance.

[0004] In the assembled state, the ideal design of a balancing shaft is such that the center of the bearing ring lies on the (operating) axis of rotation of the balancing shaft. More specifically, the center of the outer surface of the bearing ring ideally lies on the axis of rotation because the outer surface forms the inner raceway of the needle roller bearing that rolls on it and thus rotates without concentricity deviation. However, it is well known that this ideal situation does not occur in practice due to unavoidable component tolerances.

[0005] It is therefore an object of the present invention to provide a method with which a balancing shaft of the type mentioned in the introduction can be produced and in which the assembled bearing rings have the highest possible concentricity with respect to the shaft axis of rotation.

[0006] This object is achieved by the features of claim 1. The balancing shaft produced according to the method of the invention is the subject of independent device claim 7.

[0007] Therefore, the manufacturing method should include the following steps:

[0008] i) Align the unbalanced shaft with the shaft reference so that the shaft reference point of the unbalanced shaft has

[0009] Predetermined distance;

[0010] ii) Measure or check the distance between the shaft balance point on the bearing journal and the shaft reference;

[0011] iii) selecting a bearing ring from a group classification based on the measured or inspected distance, wherein the group root of the group classification

[0012] According to the different inner diameters D of the bearing rings i-LR to classify;

[0013] iv) Assemble the bearing ring onto the bearing journal.

[0014] A shaft reference point is a point on the unbalanced shaft that has a target distance from the axis of rotation of the unbalanced shaft. The manufacturing method according to the present invention essentially corresponds to the following process: The desired axis of rotation of the unbalanced shaft is first assigned to two shaft reference points via shaft references. The dimensional deviation of the shaft balance point on the bearing journal from the desired axis of rotation is then determined by measuring or checking the actual distances of the shaft balance point from the shaft references. Based on these actual distances, a bearing ring to be mounted on the bearing journal is selected from a group assortment. The dimensional deviation is compensated for by the inner diameter of the group-specific bearing ring so that its center ideally lies on the axis of rotation of the unbalanced shaft.

[0015] Further features of the invention are apparent from the following description and the accompanying drawings, in which the invention is explained with reference to exemplary embodiments.

[0016] Figure 1 A perspective view shows a balancing shaft manufactured according to the present invention;

[0017] Figure 2 shows a side view of an unbalanced shaft with schematic dimensions;

[0018] Figure 3 Show the basis Figure 1 Section II rotated 90°.

[0019] Figure 1 The balancing shaft 1 according to the invention is shown, which is used to balance the second-order free mass forces of an inline four-cylinder reciprocating piston internal combustion engine. In this typical application, two balancing shafts 1 rotate in opposite directions at twice the crankshaft speed. Figure 2The balancing shaft 1 comprises an unbalanced shaft 2 made as a cast or forged part, which has an end-side drive journal 3 for mounting a drive wheel (not shown) thereon, and has unbalanced sections 4, 5 and 6 and bearing journals 7 and 8, at which the forces generated by the unbalance are transmitted to the crankcase of the internal combustion engine. The unbalance corresponds to the center of mass 9 of the unbalanced shaft 2, which is located at Figure 3 The center of mass, symbolically represented as a point, extends at a distance from its (operating) axis of rotation 10 and, together with the axis of rotation, spans an imbalance plane 11. Balancing shaft 1 also includes a bearing ring 12 and a further bearing ring 13, which are mounted on bearing journal 7 and further bearing journal 8 and serve as inner raceways for a needle ring 14 rolling thereon. Needle ring 14 is a universal component.

[0020] The bearing journals 7, 8 are radially set back relative to the adjacent unbalanced sections 4 and 5 or 5 and 6. Therefore, in order to fit the bearing rings 12, 13 onto the bearing journals 7, 8, the respective envelope circle diameters d H must be smaller than the corresponding inner diameter D of the inner side surface 15 of the bearing rings 12, 13 in contact with the bearing journals 7, 8 i-LR . Figure 3 The enveloping circle 16 shown by the dashed line should be understood as the smallest circle that completely surrounds the corresponding bearing journal cross section. Therefore, the following relationship is satisfied: H <D i-LR .

[0021] The axis of rotation 10 of the balancing shaft 1 ideally extends through the geometric center of the drive journal 3 and the inner raceway of the needle ring 14 formed by the bearing rings 12, 13. The object of the method for manufacturing the balancing shaft 1 (as described below with the aid of Figure 2 This ideal state is achieved as described above. The unbalanced shaft 2 is first aligned with the shaft reference 17 so that the shaft reference points 18 and 19 of the unbalanced shaft 2 are at predetermined distances 20 and 21, respectively, from the shaft reference 17. The shaft reference 17 is formed, for example, by a support prism into which the drive journal 3 and the further bearing journal 8 are inserted, so that the shaft reference points 18 and 19 are at a distance 20 or 21, respectively, from the shaft reference 17. In this aligned state, the distance 22 between the shaft equilibrium point 23 on the bearing journal 7, which is axially located between the shaft reference points 18 and 19, and the shaft reference 17 is then measured. Alternatively, the distance 22 is checked. The shaft equilibrium point 23 and the shaft reference points 18 and 19 are both located on the side of the axis of rotation 10 in the unbalance plane 11 relative to the center of mass 9.

[0022] In the next step, the bearing ring 12 is selected from the group classification according to the measured or checked distance 22, where the groups G1 to G n The inner diameter D of the bearing rings varies depending on the bearing i-LRThe nominal diameters of the outer surfaces 24 of the bearing rings 12 forming the inner raceway of the needle ring 14 are of the same size so that the wall thickness classifications of the bearing rings 12 represent equivalent group classifications. The following applies to groups G1 to G n :

[0023] D i-LR,1> D i-LR,2 >D i-LR,i >D i-LR,n

[0024] The following table lists the pairing rules for group classification using the three groups G1 to G3 as examples, where: Distance 20: 59mm

[0025] Distance 21: 50mm

[0026] Distance 22[mm] Group Wall thickness [mm] 49.963…49.986 <![CDATA[G1]]> 1.476±0.003 49.987…50.013 <![CDATA[G2]]> 1.5±0.003 50.014…50.037 <![CDATA[G3]]> 1.524±0.003

[0027] The pairing of the classified bearing rings 12 has the following effects:

[0028] The measured distance 22 is within the "small" range, so the distance of the shaft equilibrium point 23 from the intended axis of rotation 10 is, in contrast, "large." This "large" distance is compensated for by the "small" wall thickness of the bearing rings 12 from the first group G1. Consequently, the center of the inner raceway of these bearing rings 12 lies at least approximately on the axis of rotation 10.

[0029] Measured distance 22 is within the "large" range, so the distance of shaft equilibrium point 23 from intended axis of rotation 10 is, in contrast, "small." This "small" distance is compensated for by the "large" wall thickness of bearing rings 12 from third group G3. Consequently, the center of the inner raceway of these bearing rings 12 also lies at least approximately on axis of rotation 10.

[0030] The measured distance 22 and, vice versa, the distance from the shaft equilibrium point 23 to the intended axis of rotation 10 are both within the "intermediate" target range. The wall thickness of the bearing rings 12 taken from the intermediate second group G2 then corresponds to this target range, so that the center of the inner raceway of these bearing rings 12 also lies at least approximately on the axis of rotation 10.

[0031] Another bearing ring 13 is mounted on the other bearing journal 8, the dimensions of which correspond to the bearing ring 12 of the intermediate group G2. Therefore, the outer surfaces 24 of the bearing rings 12, 13, which respectively form the inner raceway of the needle roller sleeve 14, have the same nominal diameter, and their inner diameters differ by a maximum of 2x(24 μm+ / -6 μm)=60 μm.

[0032] The fastening of the bearing rings 12, 13 to the bearing journals 7, 8 is respectively achieved by Figure 3 The clamping fixture 25 shown here clamps the inner sides of the bearing rings 12 , 13 against the direction of the imbalance on the bearing journals 7 , 8 .

Claims

1. A method for manufacturing a balancing shaft (1), said balancing shaft comprising an unbalanced shaft (2) having a bearing journal (7) and a bearing ring (12) mounted on said bearing journal (7), said bearing ring having an inner side surface (15) at its inner diameter D i-LR The bearing journal (7) is in contact with the bearing journal (7), wherein the bearing journal (7) has a relationship of d H <D i-LR The outer diameter d of the envelope circle H , It is characterized by the following steps: i) aligning the unbalanced shaft (2) with a shaft reference (17) such that shaft reference points (18, 19) of the unbalanced shaft (2) are at predetermined distances (20, 21) from the shaft reference (17); ii) measuring or checking the distance (22) between the shaft balance point (23) on the bearing journal (7) and the shaft reference (17); iii) selecting the bearing ring (12) from a group classification based on the measured or checked distance (22), the groups (G1, G2, G3) of the group classification being based on the inner diameters D of the bearing rings (12) that differ from one another i-LR to classify; iv) Assembling the bearing ring (12) onto the bearing journal (7).

2. The method according to claim 1, characterized in that The shaft balance point (23) is axially located between the shaft reference points (18, 19).

3. The method according to claim 1 or 2, characterized in that The bearing journal (7) has a center of mass (9) spaced apart from the axis of rotation (10) of the unbalanced shaft (2), the center of mass together with the axis of rotation (10) spanning an unbalance plane (11), wherein the shaft equilibrium point (23) is located on the side of the axis of rotation (10) in the unbalance plane (11) relative to the center of mass (9).

4. The method according to any one of the preceding claims, characterized in that The unbalanced shaft (2) comprises a drive journal (3) and a further bearing journal (8) on which a further bearing ring (13) is mounted, wherein the shaft reference points (18, 19) are located on the drive journal (3) and the further bearing journal (8).

5. The method according to claim 4, characterized in that The group classification has exactly three groups (G1, G2, G3) which are classified according to the inner diameter D i-LR,1 >D i-LR,2 >D i-LR,3 A classification is performed, wherein the size of the further bearing ring (13) corresponds to the group classification of the second group (G2).

6. A balancing shaft (1), manufactured by the method according to claim 4 or 5, characterized in that: The outer sides (24) of the bearing ring (12) and the further bearing ring (13) form an inner raceway of the same nominal diameter for a needle ring (14) rolling thereon.

7. The balancing shaft according to claim 6, characterized in that The inner side surfaces (15) of the bearing ring (12) and the other bearing ring (13) have different inner diameters D from each other. i-LR The bearing journal (7) and the other bearing journal (8) are contacted at a position.

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