Optimized differential bolt for a bevel gear differential

Abstract

According to the invention, a bevel gear differential (1) with a differential pin (2), at least one differential gear (3), a drive gear (4), at least one output gear (5) and a differential carrier (6) is proposed, wherein the differential pin (2) rotatably supports the at least one differential gear (3) and the differential pin (2) is received in a pin receptacle (7) on both sides, wherein the differential pin (2) is in the form of a rod blank, wherein the functional surfaces (10) of the differential pin (2) have been formed by a forming process.

Description

[0001] In the state of the art, differential bolts for bevel gear differentials were machined and ground from round material.

[0002] DE 10 2019 124 527 A1 shows a cross bolt for a bevel gear differential, wherein the star-shaped projecting bolt sections are essentially circular in cross section and have flattened portions.

[0003] The illustration for Fig. 3 shows a cylindrical differential bolt for a bevel gear differential with flats.

[0004] The object of the invention is to provide a differential bolt which can be produced more economically and which has improved load-bearing capacity.

[0005] This object is achieved according to the invention by a design of the differential bolt which is determined by forming processes.

[0006] Thus, a bevel gear differential with a differential pin, at least one differential gear, a drive gear, at least one driven gear, and a differential carrier, wherein the differential pin rotatably supports the at least one differential gear and the differential pin is received in a pin receptacle on both sides, achieves this object according to the invention in that the differential pin is in the form of a bar blank, wherein the functional surfaces of the differential pin have been formed by a forming process. The aim of the invention is to completely dispense with machining operations, in particular milling. This also eliminates any waste that needs to be disposed of during the formation of the differential pin. Only when cutting the bar material to length to determine the length of the differential pin does the choice of selecting a machining process remain. According to the invention, it should be possible to retain a grinding process to increase the quality of functional surfaces.

[0007] Essentially, the differential bolt according to the invention is manufactured from a bar stock with a rectangular cross-section. This eliminates the need for machining operations to create flats for lubricant transport. The machining of flats to secure the differential bolt against rotation in the bolt receptacle of the drive gear is also eliminated, since such a surface is already present in the tool. These flats can be further shaped through a forming process, whereby the differential bolt material is further densified during forming and thus gains strength. This is advantageous over machining, particularly in the area of ​​the bolt receptacle.

[0008] If necessary, the use of molds made from bar stock can eliminate the need for hardening the differential bolt.

[0009] In addition, material can be saved in non-stressed areas, thus reducing weight by approximately 30%.

[0010] In an advantageous embodiment of the invention, the functional surfaces of the differential pin are machined exclusively by forming processes. In the "exclusively" context, machining processes with geometrically defined cutting edges (milling, drilling, etc.) are omitted. Processes with geometrically undefined cutting edges are to be retained to maintain the quality of the functional surfaces.

[0011] A further embodiment of the invention provides that the differential bolt as a rod blank has a rectangular cross-section.

[0012] According to a further development, one of the functional surfaces has been designed as a flattened surface to conduct lubricant.

[0013] A detailing provides that the flattening forms a groove extending along the main extension direction of the differential bolt, which is completely present at least in the area of ​​the bearing of the differential gear.

[0014] According to a further development, one of the functional surfaces has also been designed as a flattened area to ensure that the differential bolt is held securely against rotation by the bolt holder.

[0015] Advantageously, the pin receptacle is designed as a groove in the drive gear. This improves the contact between the differential pin and the pin receptacle, allowing either more power to be transmitted or the design of the components involved to reduce installation space.

[0016] Further detailed embodiments of the invention are shown in the figures. Fig. 1 a differential bolt according to the invention, Fig. 2 a bevel gear differential with a differential bolt according to the invention and Fig. 3 a bevel gear differential with a differential pin from the state of the art.

[0017] Fig. 1 shows a differential bolt 2 according to the invention. The differential bolt 2 is formed from a bar material with a rectangular cross-section, as can be clearly seen in the plan view of the end faces of the differential bolt 2. To improve the contact surface between the differential bolt 2 and the groove-shaped bolt receptacle 7 (see illustration for Fig. 2), starting from a flat outer surface of the bar material, a flattened portion 9 has been introduced as a functional surface 10 through a forming process - e.g., stamping. The material on this functional surface 10 is thus compacted instead of being removed by a machining process. Furthermore, the differential pin 2 has a further functional surface 10, offset by 90° to this functional surface 10, as a lubricant-promoting flattened portion 8, which has been stamped in by the forming process in such a way that a groove extending along the main extension of the differential pin 2 is formed. This groove can guide lubricant radially outwards through the bearing of a differential gear 3 along the main extension of the differential pin 2, i.e., after installation in a bevel gear differential 1, using centrifugal force.The differential gear 3 remains guided over the corners of its angular cross-section of the differential pin 2, which remained from the blank bar stock. To improve the contact of the differential gear 3 on the differential pin 2, the area between the two flattened portions 9 applied to the ends was subjected to a grinding process and formed into a bearing surface 11. This clearly transforms a flat surface into one with a circular arc in cross-section, so that the quality of the contact surface between the differential gear 3 and the differential pin 2 is maintained in order to reliably transmit forces. The two flattened portions 8 and 9 are not stamped on the same side of the differential pin 2, but are arranged offset from one another by 90° in the circumferential direction.

[0018] In addition, the two end faces of the differential bolt 2 could be machined to a discrete length dimension with a necessary tolerance.

[0019] Fig. 2 shows a bevel gear differential 1 with a differential pin 2 according to the invention. The bevel gear differential 1 has - as known from the prior art - the components: drive gear 4, two driven gears 5, two differential gears 3, whereby in this view only the differential gear 3 is illustrated at the 6 o'clock position so that the view in the 12 o'clock position of the differential pin 2 according to the invention is not blocked, the differential cage 6 and the differential pin 2 according to the invention itself.

[0020] The differential pin 2 is inserted and supported with its two ends in a pin receptacle 7 of the drive gear 4, each formed as a groove. The flattened functional surfaces 9, 10, together with the respective groove 7, form the contact and power transmission in the circumferential direction; that is, during operation of the bevel gear differential 1. The differential pin 2 is thus secured against rotation about its own longitudinal axis by its engagement in the pin receptacles 7.

[0021] The groove-shaped functional surface 8, 10 extends from one end face to the other end face of the differential pin 2 and thus also through the respective differential gear 3. Thus, lubricant can be transported radially along this groove-shaped functional surface 8, 10.

[0022] Fig.Figure 3 shows a prior art bevel gear differential 101 with a differential pin 102. The circular cross-section of the differential pin 102 clearly shows a flattened portion 108, which was machined. The round cross-section of the differential pin 2 has also been ground to optimize the reception of the differential gear 103. It is already clear from the comparison that the surface of the differential pin 102 to be ground is significantly larger than the surface of the differential pin 2 according to the invention. List of reference symbols 1 bevel gear differential 2 differential bolts 3 balance wheel 4 drive wheel 5 Output gear 6 Differential cage 7 Bolt holder 8 Flattening (for lubricant) 9 Flattening (for anti-twist protection) 10 functional areas 11 Bearing surface (balance gear) 101 Bevel gear differential 102 differential bolts 103 balance wheel 104 Drive wheel 105 Output gear 106 Differential cage 107 Bolt holder 108 Flattening (for lubricant)

Claims

[1] Bevel gear differential (1) with a differential pin (2), at least one differential gear (3), a drive gear (4), two driven gears (5) and a differential carrier (6), wherein the differential pin (2) rotatably supports the at least one differential gear (3) and the differential pin (2) is received in a pin receptacle (7) on both sides, characterized by that the differential bolt (2) was in the form of a bar blank with a rectangular cross-section, wherein functional surfaces (10) of the differential bolt (2) were formed by a forming process, wherein the machining of flattened portions for securing the differential bolt (2) against rotation in the bolt receptacle (7) of the drive wheel (4) was dispensed with, and wherein the differential bolt (2) is inserted and mounted with its two ends in a bolt receptacle (7) of the drive wheel (4) designed as a groove. [2] Bevel gear differential (1) with a differential pin (2) according to claim 1, characterized by that the functional surfaces (10) of the differential bolt (2) have been machined exclusively by forming processes. [3] Bevel gear differential (1) with a differential bolt (2) according to one of the preceding claims, characterized by that one of the functional surfaces (10) has been designed as a flattening (8) for conducting lubricant. [4] Bevel gear differential (1) with a differential pin (2) according to claim 3, characterized by that the flattening (8) forms a groove extending along the main direction of extension of the differential bolt (2) as an impression, which groove is completely present at least in the area of ​​the bearing of the differential gear (3).

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