Deformation-optimized planetary pins

Abstract

The invention relates to a planetary pin (101), the outer contour of which extends at a distance r(x) from the central axis (109) of the planetary pin (101) in at least one longitudinal section according to the axial position x. For at least one interval [x1, x2], it is established that: r(x)=l(x)+g(x)+o(x), for all x∈[x1, x2], where l(x) is a linear function; where g is constant at zero or convex in the interval [x1, x2]; where o(x0)=0 is established for at least one x0∈(x1, x2); and where the function o is concave in the interval [x1, x0], convex in the interval [x0, x2], and descending in x0.

Description

[0001] The invention relates to a planet pin according to the preamble of claim 1 .

[0002] Planet pins, ie pins which are fixed in the planet carrier for supporting the planet gears, usually deform, for example due to forces generated in the teeth of the planet gears or due to loads caused by the torque to be transmitted by the planet carrier.

[0003] Deformations of planetary pins are critical, especially in the case of planetary gears that are supported in a sliding manner. A prerequisite for the wear-free operation of a sliding bearing is a large-area lubricating film. However, deformations lead to local ruptures of the lubricating film, which causes the bearing shells to come into contact and solid friction to form. This results in increased wear at the corresponding locations.

[0004] From documents US Pat. No. 8,790,213 B1 and JP-H 09,177,758 A1, plain bearings are known whose running surfaces have a spherical profile. This compensates for deflections that may be caused, for example, by radial forces. However, deformations caused by axial forces are not compensated.

[0005] The loads occurring in the planetary gear train are accompanied by an S-shaped deformation of the planet pins. Such deformations are particularly prominent in the highly loaded gear trains of wind turbines. Solutions for compensating for the S-shaped deformation are hitherto unknown.

[0006] The invention is based on the object of increasing the wear resistance of slidingly supported planetary gears.

[0007] This object is achieved by a planet pin according to claim 1. Preferred developments are contained in the dependent claims.

[0008] The invention proposes a targeted correction of the outer contour of the planet pin in at least one longitudinal section. The longitudinal section is a cross-sectional illustration defined in accordance with DIN ISO 128-40 and DIN ISO 128-50. In the invention, the section plane is oriented such that it contains the center axis of the planet gear fixed or mounted on the planet pin. The center axis is identical to the axis of rotation of the planet gear.

[0009] The center axis extends through the planet pin and intersects the planet pin only at the point which forms the area centroid of the cross section oriented orthogonally to the center axis. In the case of a rotationally symmetrical planet pin, the axis of symmetry of the planet pin is simultaneously the center axis.

[0010] The outer contour is the body edge of the planet pin in the unloaded state. If no forces act on the planet pin, it is assumed to be in the unloaded state.

[0011] The outer contour of the planet pin is described by the function r(x). Depending on the axial position x, the outer contour extends at a distance r(x) from the center axis of the planet pin. This means that at least a part of the outer contour is a graph of the function r(x). The axial position refers to a point of the center axis. The point of the center axis is defined by a distance x from a reference point that is also located on the center axis. The points of the outer contour are at a distance r(x) orthogonally to the points of the center axis.

[0012] According to the present invention, r(x) is composed of three sub-functions as follows on at least one interval [x1, x2]:

[0013] r(x)=l(x)+g(x)+o(x),

[0014] For all x∈[x1,x2], where l(x) is a linear function.

[0015] Here, for example, x1 may be 0, so that the reference point is located at x1.

[0016] The function g is convex in the interval [x1, x2]. That is, the function g provides a convex correction to the linear course of the outer correction of the planet pin.

[0017] In order to compensate for the S-shaped deformation of the planet pin, an additional S-shaped correction is performed. The corresponding correction function o extends in an S-shape. In detail, o(x0)=0 is true for at least one x0∈(x1, x2), wherein the function o is concave on the interval [x1, x0], convex on the interval [x0, x2], and descends at x0, that is, o′(x0)<0 is true.

[0018] In a preferred development, the function g is continuous and / or the function o is continuous.

[0019] In another preferred refinement, the function l is positive in the interval [x1, x2].

[0020] l can be improved into a constant function, or can be improved into a decreasing function, where l(x1)>l(x2).

[0021] In a preferred development, the function g has a minimum value on the interval (x1, x2).

[0022] In particular, g can be negative in the interval (x1, x2). This means that for all x0∈(x1, x2) it is true that g(x)<0.

[0023] In another preferred improvement, it is established that:

[0024] g(x1)=g(x2)=0.

[0025] The function g is preferably greater than -1 on the interval [x1, x2]. This means that for all x∈[x1, x2]:

[0026] g(x)>-l(x).

[0027] Furthermore, a mirror-symmetric improvement of g on the interval [x1, x2] is preferred. Established by:

[0028] r(x)=r(x1+x2-x)

[0029] In a preferred development, the function o has a maximum value in the interval [x1, x0].

[0030] Furthermore, it is preferred that the value of the function o in the interval [x1, x0[ is positive.

[0031] In another preferred development, the function o has a minimum value in the interval [x0, x2].

[0032] The value of the preferred function o on the interval [x0, x2] is negative.

[0033] In another preferred improvement, it is established that:

[0034] o(x1)=o(x2)=0.

[0035] The preferred embodiment of the present invention is shown in the accompanying drawings. In the accompanying drawings:

[0036] Figure 1 A conventional planet pin is shown in detail;

[0037] Figure 2 A deformation optimized planet pin is shown in detail; and

[0038] Figure 3 The deformation-optimized planet pin is shown in detail under load.

[0039] exist Figure 1 The planet pin 101 shown in FIG. 1 is fixed in a planet carrier 103 . By means of a sliding bearing 105 , a planet gear 107 is rotatably mounted on the planet pin 101 .

[0040] The planet carrier 103 is deformed due to the load generated during operation. The first cheek plate 103a and the second cheek plate 103b of the planet carrier 103 are displaced from each other. This causes the planet pin 101 to deform in an S shape. Therefore, the center axis 109 of the planet pin 101 extends in an S shape. Since the planet pin is cylindrical in an unloaded state, the axial body edge of the planet pin extends parallel to the center axis 109 and therefore also extends in an S shape in a loaded state.

[0041] The deformation of the planet pin 101 affects the bearing clearance 111 of the sliding bearing 105. Due to the S-shaped course of the outer contour, the bearing clearance increases at certain locations. The bearing clearance decreases at certain locations. In the area where the bearing clearance decreases, this leads to solid friction. This leads to a local increase in wear.

[0042] exist Figure 2 2 shows a planet pin 201 optimized for deformation. The contour of the planet pin 201 is corrected so that the S-shaped deformation is largely compensated. This can be achieved by the S-shaped course of the outer contour. The course of the outer contour corresponds to the flattened negative contour of the S-shaped course of the center axis 109 under load.

[0043] The planet pin 201 is composed of three sections-a first end section 203, a second end section 205 and a middle section 207. The middle section 207 is axially arranged between the first end section 203 and the second end section 205 and connects the two end sections 203, 205 to each other. The end sections 203, 205 are used to fix the planet pin 201 in each cheek plate of the planet carrier. Correspondingly, the end sections 203, 205 are cylindrical.

[0044] The diameter d1 of the first end section 203 is smaller than the diameter d2 of the second end section 205 .

[0045] Based on the conical basic shape of the middle section 207, which is caused by the different diameters of the end sections 203, 205, the planet pin 201 is corrected in two steps in a deformation-optimized manner: In a first step, the contour of the middle section 207 is corrected in such a way that a concave course is obtained. For this purpose, a concave correction function is superimposed on the truncated cone-shaped middle section 207. Figure 2 The concave correction after the first step is depicted as a dashed line in FIG.

[0046] In a second step, an S-shaped correction is performed on the concave middle section 207. For this purpose, an S-shaped correction function is superimposed on the contour of the concave middle section 207. The S-shaped correction function causes the concavity on the first end section 203 to increase and the concavity on the second end section 205 to decrease.

[0047] The application of the first and second steps to the deformation-optimized correction of the planet pin 203 is a calculation method. Ultimately, a profile is produced as a result of the calculation method.

[0048] Figure 3 The deformation-optimized planet pin 203 is shown under load. Figure 1 This corresponds to the trend shown in .

[0049] For clarity, in Figure 3 In FIG. 1 , a solid line is drawn showing the assumed course of the outer contour of the planet pin 201 without correction. This course is consistent with that in FIG. Figure 1 The direction of the outer contour of the planet pin 101 shown in FIG. 1 corresponds to FIG. 2 . It can be seen that the above correction makes the direction of the outer contour straighter. This makes the direction of the bearing gap 111 more uniform.

[0050] List of Reference Numerals

[0051] 101 Planetary Pin

[0052] 103 Planet carrier

[0053] 103a Cheek plate

[0054] 103b Cheek Plate

[0055] 105 Sliding bearings

[0056] 107 Planetary gear

[0057] 109 Central Axis

[0058] 111 Bearing clearance

[0059] 201 Planetary Pin

Claims

1. A planetary pin (101), wherein the outer contour of the planetary pin extends in at least one longitudinal section at a distance r(x) from a central axis (109) of the planetary pin (101) according to an axial position x, characterized in that: For at least one interval [x1, x2], the following holds: r(x)=l(x)+g(x)+o(x), For all x∈[x1,x2], where l(x) is a linear function; g is constant at zero or is a convex function on the interval [x1, x2]; and where o(x0)=0 is true for at least one x0∈(x1,x2); where The function o is a concave function on the interval [x1, x0], a convex function on the interval [x0, x2], and is decreasing at x0.

2. The planetary pin (101) according to claim 1, characterized in that: The functions g and / or o are continuous.

3. The planetary pin (101) according to claim 1 or 2, characterized in that: The function l is positive on the interval [x1, x2].

4. The planetary pin (101) according to claim 1 or 2, characterized in that: l is a constant function.

5. The planetary pin (101) according to claim 1 or 2, characterized in that: Established by: l(x1)>l(x2).

6. The planetary pin (101) according to claim 1 or 2, characterized in that: The function g has a minimum value on the interval (x1, x2).

7. The planetary pin (101) according to claim 1 or 2, characterized in that: The value of the function g in the interval (x1, x2) is negative.

8. The planetary pin (101) according to claim 1 or 2, characterized in that: Established by: g(x1)=g(x2)=0.

9. The planetary pin (101) according to claim 1 or 2, characterized in that: For all x∈[x1,x2], it is true that: g(x)>-l(x).

10. The planetary pin (101) according to claim 1 or 2, characterized in that: The function g is mirror-symmetric on the interval [x1, x2].

11. The planetary pin (101) according to claim 1 or 2, characterized in that: The function o has a maximum value on the interval [x1, x0].

12. The planetary pin (101) according to claim 1 or 2, characterized in that: The value of the function o in the interval [x1, x0] is positive.

13. The planetary pin (101) according to claim 1 or 2, characterized in that: The function o has a minimum value on the interval [x0, x2].

14. The planetary pin (101) according to claim 1 or 2, characterized in that: The value of the function o in the interval [x0, x2] is negative.

15. The planetary pin (101) according to claim 1 or 2, characterized in that: What holds true is: o(x1)=o(x2)=0.

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