Balance shaft

Abstract

The invention relates to a balancing shaft, comprising:-an unbalanced shaft (1), which has a centre of gravity (9) spaced apart from the axis of rotation (8) thereof, which centre of gravity forms an unbalance plane (10) with the axis of rotation, and which has a bearing journal (6, 7), which has an only partially cylindrical circumference, the cylindrical partial circumference (11) of the bearing journal is oriented unbalanced towards the shaft,-a bearing ring (13) surrounding the bearing journal, which bears against the cylindrical partial circumference and defines a free space together with a bearing journal back (12) radially opposite the cylindrical partial circumference, and-a leaf spring (14), the leaf spring is tensioned in the free space on the one hand against the back of the bearing journal and on the other hand against the bearing ring, and the bearing ring is tensioned radially against the cylindrical partial circumference, characterized in that the leaf spring is tensioned against two bearing points (20, 21) of the back of the bearing journal, the two bearing points extend on both sides of the imbalance plane and the orthographic projections of the two bearing points on the imbalance plane extend on the same side of the axis of rotation with respect to the center of gravity.

Description

Technical Field

[0001] The present invention relates to a balancing shaft, comprising:

[0002] an unbalanced shaft having a center of gravity spaced apart from its axis of rotation, said center of gravity forming an unbalance plane with the axis of rotation, and having a bearing journal having an only partially cylindrical circumference, the cylindrical part of the circumference of the circumference being oriented toward the shaft imbalance,

[0003] a bearing ring which surrounds the bearing journal, which rests against the cylindrical partial circumference and, together with the bearing journal back which lies radially opposite the cylindrical partial circumference, delimits a free space,

[0004] and a leaf spring which is tensioned in free space on the one hand against the bearing journal back and on the other hand against the bearing ring and tensions the bearing ring radially against the cylindrical part circumference. Background Art

[0005] DE 10 2019 101 319 A1 discloses a balancing shaft of this type having an unbalanced shaft and a bearing ring, which is fastened to a bearing journal of the unbalanced shaft by means of a leaf spring clamped between the bearing ring and the back of the bearing journal. At the back of the bearing journal, a reinforcing rib, which acts in opposition to the running shaft bending, extends in the direction of the axis of rotation, against the ridge of which the leaf spring is tensioned. Summary of the invention

[0006] The invention is based on the object of specifying a balancing shaft of the type mentioned in the introduction which has an improved clamping of the bearing rings.

[0007] The solution to this object is obtained by the features of claim 1. Therefore, the leaf spring should be braced against two bearing points on the back of the bearing journal, which extend on both sides of the imbalance plane and whose orthographic projections on the imbalance plane extend on the same side of the rotation axis with respect to the center of gravity. In contrast to the cited prior art, no rotational freedom is retained for the leaf spring clamped in free space, the rotational installation position of which is clearly defined and stabilized due to the position of the two bearing points on the back of the bearing journal on the one hand and the clamping relative to the bearing ring on the other hand. As a result, the leaf spring can no longer be twisted indefinitely or rotated with the bearing ring during the rotational sliding of the bearing ring. The term "bearing point" is understood to mean, depending on the contact of the leaf spring with the back of the bearing journal, its contact point or, in the case of line contact or surface contact, its line center of gravity or surface center of gravity. BRIEF DESCRIPTION OF THE DRAWINGS

[0008] Further features of the invention are apparent from the following description and the accompanying drawings, in which an exemplary embodiment of a balancing shaft according to the invention is shown. Unless otherwise mentioned, identical or functionally identical components or features are provided with the same reference numerals. The accompanying drawings show:

[0009] FIG. 1 shows a perspective view of a balancing shaft known from the prior art cited at the outset;

[0010] Figure 2 The bearing journal of the first balancing shaft according to the invention is shown as a perspective partial view;

[0011] Figure 3 The bearing journal of the second balancing shaft according to the invention is shown as a perspective partial view;

[0012] Figure 4 The longitudinal section diagram shows Figure 3 The bearing journal;

[0013] Figure 5 As a single component shown in three dimensions relative to Figure 3 and Figure 4 Alternative leaf spring. DETAILED DESCRIPTION

[0014] The known balancing shaft according to reference FIG. 1 comprises an unbalanced shaft 1 which is manufactured as a cast or forged part and has a drive journal 2 at the end for a drive wheel (not shown) to be mounted thereon, and has unbalanced sections 3, 4 and 5, and bearing journals 6 and 7 which connect two of the unbalanced sections 3 and 4 or 4 and 5, respectively. The unbalanced shaft 1 has a center of gravity 9 which is spaced apart from its axis of rotation 8 and which is centered according to the axis of rotation 8. Figure 2 The unbalance plane 10 is formed with the axis of rotation 8. In order to maximize the shaft unbalance, the bearing journals 6, 7 are only partially cylindrical and their cylindrical partial circumference 11 (see Figure 2 The surface enclosed by the dashed line in FIG. 1 is oriented such that the imbalances of the unbalanced sections 3 to 5 and the imbalances of the bearing journals 6, 7 are substantially parallel and directed in the same direction and load the cylindrical partial circumference 11 substantially in the middle of the circumference. The (non-cylindrical) partial circumference of the bearing journals 6, 7 which is radially opposite to the cylindrical partial circumference 11 is referred to below as the bearing journal back 12 and is decoupled from the rotation path of the cylindrical partial circumference 11 about the rotation axis 8.

[0015] The balancing shaft further comprises a bearing journal 6, 7, a bearing ring 13 surrounding the bearing journal, a leaf spring 14 which detachably fastens the bearing ring 13 (without damage) on the bearing journal 6, 7, and a needle roller ring 15 for radially needle-rolling the balancing shaft in the housing of the internal combustion engine. The inner raceway of the needle roller ring 15 is formed by the bearing ring 13. The leaf spring 14, which is made of spring-hardened sheet metal, has an approximately half-moon-shaped cross section and is inserted in a radial free space under elastic deformation, which is bounded on the one hand by the bearing journal back 12 and on the other hand by the inner side surface of the bearing ring 13. In this case, the radial preload of the leaf spring 14 loads the bearing ring 13 in the direction opposite to the direction of the shaft imbalance, so that the bearing ring 13 is tensioned against the cylindrical partial circumference 11. 1 , the leaf spring 14 is open in the region of the bearing journal back 12, wherein the spring ends 16 and 17 delimiting the opening are tensioned against the ridge 18 of the reinforcing rib 19 extending in the longitudinal direction of the unbalanced shaft 1. There is no further bearing contact of the leaf spring 14 with the bearing journal back 12, so that in the event of a rotational slip of the bearing ring 13, the leaf spring 14 can rotate with the bearing ring.

[0016] exist Figure 2 In the balancing shaft shown, such an uncontrolled co-rotation of the bearing ring 13 is prevented by the contact geometry (explained below) of the leaf spring 14 with the bearing journal back 12. According to the invention, the leaf spring 14 is tensioned against two bearing points 20 and 21 of the bearing journal back 12, which extend on both sides of the imbalance plane 10 and in the present case beside the reinforcing rib 19 and whose orthographic projection on the imbalance plane 10 extends on the same side of the rotation axis 8 with respect to the center of gravity 9. As is known, the orthographic projection is the vertical image of a point on a plane. Figure 3 The orthogonal projection of the bearing point 21 is shown as a point shown in black below the rotation axis 8. The bearing conditions and the clamping of the leaf spring 14 relative to the bearing ring 13 determine the rotational position of the leaf spring 14 relative to the rotation axis 8, so that the aforementioned torsion or follow-up rotation of the leaf spring 14 is excluded.

[0017] exist Figure 2 In the embodiment of , the cylindrical partial circumference 11 is radially set back relative to the shoulders 22 and 23 of the unbalanced shaft 1 , wherein the shoulders 22 , 23 surround the end face 24 of the bearing ring 13 with a narrow axial gap, thereby preventing the bearing ring 13 from moving on both sides on the bearing journal 6 and / or 7 .

[0018] Figure 3 and Figure 4A detailed view of a second balancing shaft according to the invention is shown. In this case, the axial fastening of the bearing ring 13 on the bearing journal 6 and / or 7 is carried out exclusively by means of a leaf spring 14, which is axially connected in a form-fitting manner to the bearing ring 13 on the one hand and to the bearing journal back 12 on the other hand. The axial form-fit of the leaf spring 14 with the bearing ring 13 is formed in the present case by four projections 25 of the leaf spring 14, which as sheet metal webs cut out and deformed radially outwards axially surround the bearing ring 13 at the end face 24 of the bearing ring. The axial form-fit of the leaf spring 14 with the bearing journal back 12 is formed by projections and / or recesses of the leaf spring 14 and of the bearing journal back 12 which engage with one another and in this case by means of the bearing journal back 12 having one or two grooves 26 extending on both sides of the reinforcing rib 19, the groove walls of which surround the axial end face 27 of the leaf spring 14 in the axial direction with little play. The groove 26 may alternatively be replaced by a single groove located on the ridge line 18 of the reinforcing rib 19 .

[0019] Figure 5 The leaf spring 14 of the third balancing shaft according to the invention, shown as a single component in FIG, has a recess 28 into which a projection (not shown) on the bearing journal back 12 engages, thereby establishing an axial form fit between the leaf spring 14 and the bearing journal back 12 .

[0020] All leaf springs 14 shown above are open circumferentially, wherein the opening 29 of each leaf spring 14 is located in a circumferential region of the bearing ring 13 which is opposite the cylindrical partial circumference 11 .

Claims

1. A balancing shaft, comprising: an unbalanced shaft (1) having a center of gravity (9) spaced apart from its axis of rotation (8), said center of gravity forming an unbalance plane (10) with said axis of rotation (8), and having a bearing journal (6, 7) having an only partially cylindrical circumference, a cylindrical part of the circumference (11) of which is oriented towards the shaft imbalance, a bearing ring (13) surrounding the bearing journal (6, 7), which bears against the cylindrical partial circumference (11) and, together with a bearing journal back (12) lying radially opposite the cylindrical partial circumference, defines a free space, - and a leaf spring (14) which, in the free space, is tensioned on the one hand against the bearing journal back (12) and on the other hand against the bearing ring (13) and tensions the bearing ring (13) radially against the cylindrical partial circumference (11), Characterized in that the leaf spring (14) is tensioned against two bearing points (20, 21) of the bearing journal back (12), the two bearing points extending on both sides of the imbalance plane (10) and the orthographic projections of the two bearing points on the imbalance plane (10) extending on the same side of the rotation axis (8) with respect to the center of gravity (9).

2. The balancing shaft according to claim 1, characterized in that: The leaf spring (14) prevents the bearing ring (13) from shifting on both sides on the bearing journal (6, 7), wherein the leaf spring (14) is axially connected in a form-fitting manner to the bearing journal back (12) on the one hand and to the bearing ring (13) on the other hand.

3. The balancing shaft according to claim 2, characterized in that: The axial positive fit of the leaf spring (14) with the bearing ring (13) is formed by a radial projection (25) of the leaf spring (14), which axially surrounds the bearing ring (13) at the end face (24) of the bearing ring.

4. The balancing shaft according to claim 2 or 3, characterized in that: The axial positive fit of the leaf spring (14) and the bearing journal back (12) is formed by projections and / or recesses of the leaf spring (14) and the bearing journal back (12) which engage with each other.

5. A balancing shaft according to any one of the preceding claims, characterized in that The leaf spring (14) is open circumferentially, wherein the opening (29) of the leaf spring (14) is located in a circumferential region of the bearing ring (13) that is opposite the cylindrical partial circumference (11).

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