Automotive rotating electric machine drive assembly

Abstract

To improve the retention of a connecting part integrally mounted on a shaft so as to be rotatable and translatable. [Solution] The drive assembly comprises a rotor shaft (2) extending along a longitudinal axis (X) and a connecting piece providing a connection between the shaft and a torque transmission system (4), the torque transmission system (4) comprising a bore (41) for the passage of the rotor shaft, the bore having a first wall (41a) and a cylindrical second wall (41b) extending axially in alignment with the first wall, the rotor shaft having a first surface (21) extending axially that cooperates with the first wall of the bore to center the connecting piece around the rotor shaft, and a cylindrical second surface (22) extending axially and provided with a knurled portion, the knurled portion having a diameter (A) larger than the diameter (A') of the second wall of the bore, and the connecting piece being press-fitted onto the rotor shaft using the knurled portion.

Description

Technical Field

[0001] The technical field of the present invention is the field of rotary electrical machines such as alternators or starter - alternators equipped in combustion engine vehicles.

[0002] The present invention relates to a drive assembly of a rotary electrical machine comprising a rotor shaft and a connecting component (such as a pulley or a pinion) providing connection between the shaft and a torque transmission system (such as a belt or a chain).

Background Art

[0003] Combustion engine vehicles are equipped with an alternator having a function of converting mechanical energy into electrical energy, particularly for the purpose of recharging the vehicle battery or supplying power to the vehicle's on - vehicle power grid.

[0004] An alternator is a rotary electrical machine having a shaft with a pulley attached. This pulley is connected by a belt to another pulley attached to the crankshaft of the engine. The belt transmits the rotational movement of the crankshaft to the shaft of the alternator.

[0005] It is common to use a retaining nut to rotatably lock the pulley around the shaft. However, the clamping force generated by such fixing means may not be sufficient to hold the pulley integrally with the shaft. In fact, during the operation of the alternator, especially when the pulley is subjected to high torque, the nut is likely to loosen.

[0006] Therefore, it seems necessary to improve the rotatable locking of the pulley around the shaft.

Summary of the Invention

[0007] The present invention provides a solution for improving the retention of a connecting component (e.g., a pulley or pinion) that provides a connection between a shaft and a torque transmission system (e.g., a belt or chain), which is integrally mounted on the shaft in a rotatable and translatably manner.

[0008] A first aspect of the present invention is a drive assembly for an automobile rotating electric machine, the drive assembly comprising a rotor shaft extending along a longitudinal axis and a connecting component providing a connection between the shaft and a torque transmission system, the torque transmission system comprising a bore for the passage of the rotor shaft, the bore comprising a first wall extending axially and a cylindrical second wall extending axially and aligned with the first wall, the rotor shaft -A first surface extending in the axial direction, which cooperates with the first wall of the bore to center the connecting component around the rotor shaft, -A second cylindrical surface extending in the axial direction and having a knurled section, Equipped with, The knurled portion has a diameter larger than the diameter of the second wall of the bore, and the connecting component relates to an assembly that is pressure-fitted to the rotor shaft using the knurled portion.

[0009] The knurled portion consists of multiple protrusions that cut grooves into the bore wall when the connecting component is pressure-fitted onto the shaft. Therefore, the present invention ensures that the connecting component is mounted in a centered manner while ensuring that the connecting component is rotatably locked to the shaft using the knurled portion.

[0010] A drive assembly according to a first aspect of the present invention may comprise one or more of the following features, either individually or in combination as technically possible: - The first surface of the rotor shaft and the first wall of the bore are cylindrical surfaces having the same diameter. - The first surface of the rotor shaft and the first wall of the bore each exhibit surface characteristics having irregularities having dimensions smaller than the characteristic dimensions. - The connecting component is mounted at the level of the first end of the rotor shaft, the diameter of the first surface of the rotor shaft is greater than the diameter of the knurled portion, and the knurled portion is positioned between the first surface and the first end of the rotor shaft. - The diameter of the first surface of the rotor shaft is in the range of 1 to 2 times the diameter of the knurled portion. - The connecting component is mounted at the level of the first end of the rotor shaft, the diameter of the first surface of the rotor shaft is smaller than the diameter of the knurled portion, and the first surface is positioned between the knurled portion and the first end of the rotor shaft.

[0011] A second aspect of the present invention relates to a rotating electromachine comprising a drive assembly according to the first aspect of the present invention.

[0012] The present invention and its various applications will be better understood by reading the following description and examining the accompanying drawings. [Brief explanation of the drawing]

[0013] [Figure 1] This is a partial schematic cross-sectional view in the longitudinal direction of an embodiment of the alternator according to the present invention. [Figure 2] Figure 1 is a schematic diagram of a partially exploded view of a first embodiment of the alternator drive assembly. [Figure 3] Figure 1 is a partially exploded schematic diagram of a second embodiment of the alternator drive assembly. [Modes for carrying out the invention]

[0014] These drawings are for illustrative purposes only and do not limit the invention in any way.

[0015] For greater clarity, identical or similar elements are indicated by the same reference numeral in all drawings.

[0016] An embodiment of the alternator 100 according to the present invention will be described with reference to Figure 1. An alternator is a rotating electric machine configured to convert mechanical energy from a combustion engine vehicle into electrical energy. According to another embodiment of the present invention, the rotating electric machine may be a starter-alternator.

[0017] The alternator 100 comprises a drive assembly including a rotor shaft 2 extending along a longitudinal axis X, and connecting components. The connecting components provide a connection between the shaft and a torque transmission system 4 which is rotatably and translatably integrally mounted to the front end of the shaft 2.

[0018] This connecting component is embodied by a pulley in the illustrated example. In this example, the torque transmission system is embodied by a belt.

[0019] In another unillustrated version, this connecting component may be represented by a pinion. In this case, the torque transmission system is represented by a chain. In the following description, the selected example is a pulley; however, it should be understood that this pulley is replaceable with a pinion.

[0020] Throughout the detailed description and claims, the terms “front,” “rear,” “forward,” and “rear” are used to describe the relative positional characteristics of the alternator 100, where the front of the alternator 100 corresponds to the end of the shaft 2 on which the pulley 4 is attached.

[0021] The alternator 100 also includes a rotor 6 rotatably and integrally mounted on the shaft 2, and a stator (not shown) surrounding the rotor 6. The stator is supported by a case (not shown) rotatably mounted on the shaft 2 by front ball bearings 71 and rear ball bearings 72 located on both sides of the rotor 6.

[0022] The shaft 2 is disposed between the rotor and the front bearing 71 and fasteners includes 25. The front bearing 71 includes an inner bearing race 71a that contacts the shaft 2 and an outer bearing race 71b. The inner race 71a of the front bearing 71 fasteners abuts against 25. The pulley 4 is firmly held to the inner race 71a by the retaining nut 8. The front end portion of the shaft 2 includes a recess 9 intended to receive a key that can lock the shaft 2 rotatably during the assembly of the pulley 4.

[0023] The combustion engine includes a rotatable crankshaft. The pulley 4 of the alternator 100 is intended to be rotated by a belt that mechanically connects the pulley 4 to a pulley rotatably and integrally mounted on the crankshaft. The rotational movement of the crankshaft is transmitted to the pulley 4, the shaft 2, and the rotor 6, and these elements are rotatably and integrally mounted.

[0024] <{ FIG. 2 is a partially exploded schematic view of a first embodiment of the drive assembly of the alternator 100. The pulley 4 includes a bore 41 for the passage of the rotor shaft 2. The bore 41 includes a first wall 41a and a second wall 41b, and these walls extend axially in alignment with each other. The second wall 41b has a cylindrical shape.

[0025] The rotor shaft 2 includes a first surface 21 and a second surface 22, and these surfaces extend axially in alignment with each other. The second surface 22 extends over the entire circumference of the shaft 2 and exhibits an overall shape complementary to the overall shape of the second wall 41b of the bore 41. The second surface 22 has a cylindrical shape.

[0026] As shown in Figure 2, the second surface 22 is provided with a knurled section. The knurled section has a diameter A that is substantially larger than the diameter A' of the second wall 41b of the bore 41. The pulley 4 is pressure-fitted onto the rotor shaft 2 using the knurled section. In addition to the retaining nut 8, the knurled section contributes to locking the pulley 4 to the shaft 2 in a rotatable and translational manner. Preferably, the diameter A of the knurled section is in the range of 1 to 1.1 times the diameter A' of the second wall 41b of the bore 41.

[0027] When the pulley 4 is assembled onto the shaft 2, the first surface 21 works in cooperation with the first wall 41a of the bore to center the pulley around the shaft 2. In fact, the knurled portion alone cannot properly align the center of the pulley 4 with the longitudinal axis X, which corresponds to the axis of rotation of the shaft 2. Through the cooperation of these centering surfaces, the axis of rotation of the pulley 4 is coupled to the axis of rotation of the shaft 2, and the pulley 4 does not lose balance.

[0028] In the embodiment shown in Figure 2, the first surface 21 of the shaft 2 and the first wall 41a of the bore 41 have a cylindrical shape with the same diameter B. Alternatively, both the first surface 21 of the shaft 2 and the first wall 41a of the bore 41 may have one or more flat surfaces that are parallel to the longitudinal axis X and arranged circumferentially. In this case, the first surface 21 of the shaft 2 and the first wall 41a of the bore 41 have a longitudinally truncated cylindrical shape, which can improve the rotatable locking of the pulley 4 on the rotor shaft 2.

[0029] The first centering surface 21 preferably extends over a length ranging from one to three times the length of surface 22. Note that surface 21 forms a functional guide zone between the shaft and the pulley.

[0030] The knurled portion preferably extends over a length in the range of 0.1 to 1 times the diameter of the shaft 2.

[0031] In the embodiment shown in Figure 2, the diameter B of the first surface 21 of the shaft 2 is greater than the diameter A of the knurled portion. Preferably, the diameter B of the first surface 21 of the rotor shaft is in the range of 1 to 2 times the diameter B of the knurled portion. In this example, the knurled portion is located in front of the first surface 21. Complementarily, the second wall 41b of the bore 41 is located in front of the first wall 41a of the bore 41.

[0032] Figure 3 shows a second embodiment of the drive assembly of the present invention. In this embodiment, the diameter B of the first surface 21 of the shaft 2 is smaller than the diameter A of the knurled portion. The diameter A of the first surface of the rotor shaft is preferably in the range of 0.5 to 1 times the diameter B of the knurled portion. In this example, the knurled portion is located behind the first surface 21. Complementarily, the second wall 41b of the bore 41 is located behind the first wall 41a of the bore 41.

[0033] Advantageously, the first surface 21 of the rotor shaft 2 and the first wall 41a of the bore 41 each exhibit surface characteristics with irregularities having dimensions smaller than characteristic dimensions. According to one embodiment, the first surface 21 and the first wall 41a are visually smooth. In another embodiment, the first surface 21 and the first wall 41a are uniform to the touch. In other words, the first surface 21 of the rotor shaft 2 and the first wall 41a of the bore 41 are configured to be substantially smooth in order to facilitate the centering of the pulley 4 with respect to the shaft 2.

[0034] Naturally, the present invention is not limited to the embodiments described with reference to the drawings, and alternative examples can be envisioned without departing from the framework of the invention. The first surface 21 of the shaft, which is positioned to center the pulley 4, may, in particular, comprise a first and second portion located on either side of the knurled portion. Furthermore, the pulley can be replaced with a pinion, and the torque transmission system can be replaced with, for example, a chain.

Claims

1. A drive assembly for an automobile rotating electrical machine (100), The drive assembly comprises a rotor shaft (2) extending along a longitudinal axis (X) and a connecting component (4) that provides a connection between the rotor shaft and a torque transmission system. The connecting component (4) is provided with a bore (41) for the passage of the rotor shaft, The bore comprises a first wall (41a) extending in the axial direction and a cylindrical second wall (41b) aligned with the first wall and extending in the axial direction. The rotor shaft is - A first surface (21) extending in the axial direction, which cooperates with the first wall of the bore to center the connecting component around the rotor shaft, - A second cylindrical surface (22) extending in the axial direction and having a knurled section, Equipped with, The knurled portion has a diameter (A) that is larger than the diameter (A') of the second wall of the bore. The connecting component (4) is pressure-fitted to the rotor shaft using the knurled portion. The connecting component (4) is attached to the first end of the rotor shaft (2), The diameter (B) of the first surface (21) of the rotor shaft is greater than the diameter (A) of the knurled portion. The knurled portion is positioned between the first surface and the first end of the rotor shaft. The rotor shaft (2) is equipped with a fastener (25), The drive assembly comprises a retaining nut (8) attached to the rotor shaft (2), and a bearing (71) including an inner race (71a) that abuts against the stopper (25) in the axial direction. The connecting component (4) is firmly held in the axial direction against the inner race (71a) by the retaining nut (8) that abuts against the connecting component (4). A drive assembly characterized by the following:

2. The retaining nut (8) is attached to the first end of the rotor shaft (2). The drive assembly according to feature 1.

3. The retaining nut (8) locks the connecting part (4) to the rotor shaft (2) along the longitudinal axis (X). The drive assembly according to claim 2, characterized in that it is as described above.

4. The first end of the rotor shaft (2) is provided with a recess (9) intended to receive a key that allows the rotor shaft (2) to be rotatably locked during assembly of the connecting component (4). The drive assembly according to any one of claims 1 to 3.

Images