Propeller shaft yoke and propeller shaft

Abstract

In the present invention, a first arm outside-edge chamfered section (115) and a second arm outside-edge chamfered section (125) are formed along both outside edges of a first arm base section (111) and a second arm base section (121), respectively. As a result, it is possible to reduce the radius of rotation of a first arm section (11) and a second arm section (12) in a first yoke (1), and it is thus possible to improve the layout of the first yoke (1) and a propeller shaft using the same.

Description

[Technical field]

[0001] The present invention relates to a propeller shaft yoke and a propeller shaft. [Background technology]

[0002] As an example of a conventional propeller shaft yoke, for example, the one described in Patent Document 1 below is known.

[0003] This propeller shaft is connected to the rotating shaft of the on-board transmission and differential via a universal joint made of a Cardan joint. This universal joint is configured by connecting a pair of yokes, a first yoke and a second yoke, which are bifurcated and opposed to each other across the rotation axis of the propeller shaft, via a cross shaft. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2018-144817 A Summary of the Invention [Problem to be solved by the invention]

[0005] However, in the yokes (first and second yokes) used in the conventional universal joint, both circumferential edges on the radial outside of the arm portion are formed as corners. In other words, the radially outer surface of the arm portion and both circumferential side surfaces connecting the radially outer surface and the radially inner surface are connected at a substantially right angle. This increases the turning radius of the arm portion, which may cause interference with other vehicle-mounted components.

[0006] In this case, a possible means for reducing the rotation radius of the arm portion is to shorten the distance between the arm portions of the first yoke and the second yoke, i.e., the distance between the outer surface of one arm and the outer surface of the other arm in the first yoke and the second yoke. However, when the size of the yoke is reduced in this way, it is necessary to design a new die for forging the yoke, which makes it difficult to contribute to reducing the manufacturing costs of the yoke and the propeller shaft.

[0007] Therefore, the present invention has been devised in consideration of the technical problems with the conventional propeller shaft yoke, and aims to provide a propeller shaft yoke and a propeller shaft that can reduce the rotation radius of the first and second arm portions without shortening the distance between the outer surfaces of the first arm portion and the second arm portion. [Means for solving the problem]

[0008] In one aspect, the present invention includes a first arm outer edge chamfered portion provided on the radial outside of a first arm base so as to extend along both circumferential edges of the rotation axis of a propeller shaft and recessed from the outside of the first arm base toward the rotation axis, and a second arm outer edge chamfered portion provided on the radial outside of a second arm base so as to extend along both circumferential edges of the rotation axis and recessed from the outside of the second arm base toward the rotation axis. Effect of the Invention

[0009] According to the present invention, the rotation radius of the first arm portion and the second arm portion can be reduced without shortening the distance between the outer surfaces of the first arm portion and the second arm portion. [Brief description of the drawings]

[0010] [Figure 1] FIG. 2 is a side view of a propeller shaft according to the present invention. [Diagram 2] 2 is a perspective view of the first universal joint shown in FIG. 1, as viewed from the shaft portion side. [Diagram 3] 2 is a perspective view of the second universal joint shown in FIG. 1, as viewed from the shaft portion side. [Figure 4] 4 is a perspective view of a first yoke of the second universal joint shown in FIG. 3, as viewed from the second yoke side. [Diagram 5] 5 is a view taken along the arrow A in FIG. 4. [Figure 6] 5 is a view taken along the arrow B in FIG. 4. [Figure 7] FIG. 4 is a front view of the cross shaft shown in FIG. [Figure 8] 6 is a cross-sectional view taken along line CC in FIG. 5. [Figure 9] FIG. 2 is a diagram comparing the rotation radius of a yoke according to the present invention with that of a conventional yoke, and is a plan view of first arm portions of the yoke according to the present invention and the conventional yoke. [Figure 10] 6 is a cross-sectional view taken along line CC in FIG. 5, showing another example of the first yoke. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] Hereinafter, an embodiment of a propeller shaft yoke and a propeller shaft according to the present invention will be described in detail with reference to the drawings. For convenience of explanation, the left side of Fig. 1 will be described as the "front" and the right side as the "rear" in the following description, and the direction along the rotation axis Z in each drawing will be described as the "axial direction," the direction perpendicular to the rotation axis Z as the "radial direction," and the direction around the rotation axis Z as the "circumferential direction."

[0012] (Propeller shaft configuration) FIG. 1 is a side view of a propeller shaft PS according to the present invention, showing the external appearance of the propeller shaft.

[0013] 1, the propeller shaft PS is disposed along the front-to-rear direction of the vehicle between a first rotating shaft (not shown) which is a rotating shaft disposed at the front of the vehicle, and a second rotating shaft (not shown) which is a rotating shaft disposed at the rear of the vehicle. For example, in a vehicle with a front engine, rear drive (FR) drive system, the first rotating shaft is disposed at the front of the vehicle and corresponds to the output shaft of a transmission to which rotational force is transmitted from a drive source such as an engine or a motor, and the second rotating shaft is disposed at the rear of the vehicle and corresponds to the input shaft of a differential which transmits rotational force to the rear wheels of the vehicle.

[0014] That is, the propeller shaft PS according to this embodiment has a two-piece structure in which the shaft portion is divided into front and rear parts, and a first shaft member S1 connected to the first rotating shaft and a second shaft member S2 connected to the second rotating shaft are connected via a third universal joint J3, which is a well-known constant velocity joint, so as to be able to rotate together about the rotation axis Z. In addition, the propeller shaft PS is rotatably supported by a center bearing CB that is suspended from the vehicle body (not shown) via a well-known bracket BKT, which is disposed near the third universal joint J3.

[0015] A front end of the propeller shaft PS is connected to the first rotating shaft (not shown) via a first universal joint J1 formed by a Cardan joint. Similarly, a rear end of the propeller shaft PS is connected to the second rotating shaft (not shown) via a second universal joint J2 formed by a Cardan joint.

[0016] (Configuration of universal joint) Fig. 2 shows a perspective view of the first universal joint J1 as viewed from the shaft side, and Fig. 3 shows a perspective view of the second universal joint J2 as viewed from the shaft side. Since the first universal joint J1 and the second universal joint J2 have roughly the same configuration, for the sake of convenience, in this embodiment, only the second universal joint J2 will be described in detail, and the configuration of the first universal joint J1 that is similar to that of the second universal joint J2 will be given the same reference numerals as those of the second universal joint J2 in Fig. 2, and a detailed description thereof will be omitted.

[0017] As shown in Figure 2, the first universal joint J1 includes a pair of yokes consisting of a first yoke 1 connected to the first shaft member S1 (see Figure 1) of the propeller shaft PS and a second yoke 2 connected to the first rotating shaft, and a cross shaft (spider) 3 interposed between the pair of yokes (first yoke 1 and second yoke 2) and connecting the two so that they can rotate relative to each other.

[0018] As shown in Figure 3, the second universal joint J2 includes a pair of yokes consisting of a first yoke 1 connected to the second shaft member S2 (see Figure 1) of the propeller shaft PS and a second yoke 2 connected to the second rotating shaft, and a cross shaft (spider) 3 interposed between the pair of yokes (the first yoke 1 and the second yoke 2) and connecting the two so that they can rotate relative to each other.

[0019] The first yoke 1 has a cylindrical base 10 as a fixed part that is fixed to the second shaft member S2 (see FIG. 1) of the propeller shaft PS by, for example, friction welding, and a pair of first and second arm parts 11, 12 that extend in parallel from a surface of the cylindrical base 10 facing the second yoke 2 toward the second yoke 2 along the rotation axis Z of the propeller shaft PS. The cylindrical base 10 and the first and second arm parts 11, 12 are integrally formed by, for example, casting.

[0020] The first and second arm portions 11, 12 are arranged symmetrically with respect to the rotation axis Z. First and second arm through-holes 110, 120 facing each other across the rotation axis Z are formed at the tips of the first and second arm portions 11, 12, penetrating in the radial direction (the direction of the radial line Y). A cylindrical needle bearing 4 is inserted between the first and second arm through-holes 110, 120 and both shaft portions 31, 33 (see FIG. 7) of the cross shaft 3, and the needle bearing 4 rotatably supports both shaft portions 31, 33 (see FIG. 7) of the cross shaft 3. The needle bearing 4 is fixed in the first and second arm through-holes 110, 120 by crimping the respective steps 110b, 120b of the first and second countersunk portions 110a, 120a which are formed with stepped diameters at the outer ends of the first and second arm through-holes 110, 120. For convenience of illustration, Fig. 3 shows a state before the respective steps 110b, 120b of the first and second countersunk portions 110a, 120a are crimped.

[0021] The second yoke 2 has a flange portion 20 formed in a generally plate shape, and a pair of arms, a first arm portion 11 and a second arm portion 12, extending in parallel from a surface of the flange portion 20 facing the first yoke 1 toward the first yoke 1 along the rotation axis Z of the propeller shaft PS. The flange portion 20 and the first and second arm portions 11, 12 are integrally formed by, for example, casting.

[0022] The flange portion 20 has a generally rectangular plate shape, has bolt through holes 201 formed at the four corners, and is connected to the first rotating shaft via bolts (not shown) that pass through the bolt through holes 201. The planar shape of the flange portion 20 can be freely changed according to the connection shape of the mating first rotating shaft, such as a circle or an irregular shape in addition to the rectangular shape exemplified in this embodiment. The same applies to the second yoke 2 of the first universal joint J1.

[0023] Furthermore, the pair of first and second arm portions 21, 22 of the second yoke 2 function as a pair with the pair of first and second arm portions 11, 12 of the first yoke 1 described above, and basically have the same configuration as the first and second arm portions 11, 12 of the first yoke 1. Therefore, for the first and second arm portions 11, 12 of the second yoke 2, the same reference numerals as the first and second arm portions 11, 12 of the first yoke 1 are used for the same configurations, and detailed explanations thereof will be omitted.

[0024] In addition, it is preferable that a tool escape recess 202 for avoiding interference with a bolt fastening tool (e.g., a socket wrench) for fastening a bolt (not shown) in each bolt through hole 201 is formed at the base end of the first and second arm portions 11 and 12 of the second yoke 2, at the side edge portion facing the adjacent bolt through hole 201, along the extending direction of the first and second arm portions 11 and 12. In other words, it is possible to arrange each bolt through hole 201 further inward in the flange portion 20 by the amount of avoidance of interference between the first and second arm portions 11 and 12 and the bolt fastening tool (not shown), which can contribute to the miniaturization of the second universal joint J2. In addition, although the formation of the tool escape recess 202 is not applied to the second yoke 2 of the first universal joint J1 shown in FIG. 2, it goes without saying that it is also effective for the first universal joint J1.

[0025] (Yoke configuration) Fig. 4 shows a perspective view of the first yoke of the second universal joint shown in Fig. 3 as seen from the second yoke side. Fig. 5 shows a view as seen from the direction A in Fig. 4. Fig. 6 shows a view as seen from the direction B in Fig. 4. Fig. 7 shows a front view of the cross shaft 3 shown in Fig. 3.

[0026] As shown in Figures 4 and 5, the first yoke 1 has a cylindrical tubular base 10 that is fixed to the second shaft member S2 (see Figure 1) of the propeller shaft PS by friction welding, and a pair of first and second arm portions 11, 12 that extend parallel to each other along the rotation axis Z from a disk-shaped yoke body portion 13 provided at the end of the cylindrical base 10 facing the second yoke 2 toward the second yoke 2.

[0027] 4 to 6, the first and second arm portions 11, 12 have first and second arm base portions 111, 121 as general portions connected to the cylindrical base portion 10, and first and second arm tip portions 112, 122 formed to protrude toward the tip side from the first and second arm base portions 111, 121 and having first and second arm cutout portions 113, 123 formed on their radially inner portions. The first arm portion 11 and the second arm portion 12 have shapes that are symmetrical with respect to the rotation axis Z, and are arranged in parallel along a tangential direction to the yoke body portion 13 on the outer circumferential edge of the yoke body portion 13 so as to face each other in the radial direction (direction of the radial line Y) with the rotation axis Z in between.

[0028] 5, the first and second arm sections 11 and 12 are tapered such that the circumferential width (the distance between the arm side surfaces 114a and 114b) gradually decreases toward the tip side. That is, the first arm section 11 is provided with a pair of arm side surfaces 114a and 114b inclined with respect to the rotation axis Z so that the pair of arm side surfaces 114a and 114b approach the rotation axis Z toward the tip side of the first arm section 11. The angles θ1 and θ2 between the pair of arm side surfaces 114a and 114b of the first arm section 11 and the rotation axis Z are preferably set to 3 degrees or less. The same series of configurations for the first arm section 11 are also applied to the second arm section 12.

[0029] As shown in Fig. 6, the first and second arm base portions 111, 121 rise almost vertically from the outer periphery of the yoke body portion 13 and are formed to be relatively thick with a generally constant thickness. Also, as shown in Fig. 5, first and second arm through-holes 110, 120 each having a circular shape in a plan view are formed at the tip side of the first and second arm base portions 111, 121 and extend through the tip along a radial line Y.

[0030] The first and second arm through-holes 110, 120 have a generally constant inner diameter, and support both shaft portions 31, 33 of the cross shaft 3 inside via a needle bearing 4 (see FIG. 3). Also, at the outer ends of the first and second arm through-holes 110, 120, first and second countersunk portions 110a, 120a for use in crimping and fixing the needle bearing 4 are formed in a stepped shape with a larger diameter than the inner circumferential surfaces of the first and second arm through-holes 110, 120, as shown in FIGS.

[0031] As shown in Fig. 5 in particular, the first and second countersunk portions 110a, 120a are provided such that both circumferential ends overlap with the first and second arm outer edge chamfered portions 115, 125 (first and second arm outer edge first R chamfered portions 115b, 125b described later) in the axial direction. The first and second countersunk portions 110a, 120a crimp the first and second step portions 110b, 120b formed at the inner ends to plastically deform the inner peripheral edges of the first and second step portions 110b, 120b inward, thereby preventing the needle bearings 4 accommodated in the first and second arm through holes 110, 120 from falling out (see Fig. 3).

[0032] In addition, on the inside of the tip portions of the first and second arm base portions 111, 121, first and second arm inner inclined portions 111c, 121c are formed in which the distance between the arm inner surfaces 111a, 121a of the first and second arm base portions 111, 121 gradually increases toward the tip, as shown in Figure 6.

[0033] 4 and 5, the first and second arm tip portions 112, 122 are provided outside the first and second arm through holes 110, 120 in the axial direction and are formed in a generally arc shape along the outer periphery of the first and second arm through holes 110, 120. Furthermore, as shown in Fig. 5, the first and second arm tip portions 112, 122 have a generally elliptical shape and the radial length L1 is set to be smaller than the axial length L2.

[0034] 6, the first and second arm notches 113, 123 are formed by recessing the arm inner surfaces 111a, 121a of the first and second arm portions 11, 12 in a stepped shape radially outward (in the direction of radial line Y). The first and second arm notches 113, 123 are provided to face the outer peripheries of the first and second arm through-holes 110, 120, and both shaft portions 31, 33 of the cross shaft 3 can be inserted into the first and second arm through-holes 110, 120 from the tip sides of the first and second arm portions 11, 12 through the first and second arm notches 113, 123.

[0035] 5, first and second arm outer edge chamfers 115, 125 are formed on both circumferential edges on the outside of the first and second arm bases 111, 121, extending along the both edges. The first and second arm outer edge chamfers 115, 125 are mainly formed by C-chamfering having a flat cut surface. The first and second arm outer edge chamfers 115, 125 are formed to have a generally constant circumferential width in the axial direction.

[0036] 6, first and second arm inner edge chamfers 116, 126 are formed on both inner circumferential edges of the first and second arm bases 111, 121, extending along the both edge edges. The first and second arm inner edge chamfers 116, 126 are mainly formed by C-chamfering having a flat cutting surface.

[0037] FIG. 8 shows a cross-sectional view of the first arm portion taken along line CC in FIG.

[0038] As shown in FIG. 8, the first and second arm bases 111, 121 have arm inner surfaces 111a, 121a and arm outer surfaces 111b, 121b that are parallel to each other, have a generally constant thickness in the axial direction (the extension direction of the first and second arm portions 11, 12), and are formed so that their cross sections are approximately rectangular.

[0039] Also, first and second arm outer edge chamfered portions 115, 125 extending along both side edges are cut out on both outer sides of the first and second arm bases 111, 121. That is, by forming the first and second arm outer edge chamfered portions 115, 125, the circumferential side edges of the first and second arm bases 111, 121 are recessed radially inward from the first and second arm tip portions 112, 122. Also, like the first and second arm outer edge chamfered portions 115, 125, first and second arm inner edge chamfered portions 116, 126 extending along both side edges are cut out on both inner sides of the first and second arm bases 111, 121.

[0040] The first and second arm outer edge chamfered portions 115, 125 have first and second arm outer edge C chamfered portions 115a, 125a with C-chamfered shapes having flat cutting surfaces, first first and second arm outer edge R chamfered portions 115b, 125b with R-chamfered shapes that smoothly connect the first and second arm outer edge C chamfered portions 115a, 125a and the arm side surfaces 114a, 124a, and first and second arm outer edge second R chamfered portions 115c, 125c with R-chamfered shapes that smoothly connect the first and second arm outer edge C chamfered portions 115a, 125a and the arm side surfaces 114b, 124b. It is preferable that the first R chamfered portions 115b, 125b on the outer edges of the first and second arms and the second R chamfered portions 115c, 125c on the outer edges of the first and second arms are both set to a R chamfer with a radius of 3 mm (R3).

[0041] Similarly, the first and second arm inner edge chamfered portions 116, 126 have first and second arm inner edge C chamfered portions 116a, 126a which have a C-chamfered shape with a flat cutting surface, first first and second arm inner edge R chamfered portions 116b, 126b which have an R-chamfered shape that smoothly connects between the first and second arm inner edge C chamfered portions 116a, 126a and the arm side surfaces 114a, 124a, and first and second arm inner edge second R chamfered portions 116c, 126c which have an R-chamfered shape that smoothly connects between the first and second arm inner edge C chamfered portions 116a, 126a and the arm side surfaces 114b, 124b. It is preferable that the first R chamfered portions 116b, 126b on the inner edges of the first and second arms and the second R chamfered portions 116c, 126c on the inner edges of the first and second arms are both set to a R chamfer with a radius of 3 mm (R3).

[0042] Here, the first and second arm outer edge C-chamfered portions 115a, 125a are formed larger than the first and second arm inner edge C-chamfered portions 116a, 126a. Specifically, the circumferential width W1 of the first and second arm outer edge C-chamfered portions 115a, 125a is set larger than the circumferential width W3 of the first and second arm inner edge C-chamfered portions 116a, 126a, and the radial width W2 of the first and second arm outer edge C-chamfered portions 115a, 125a and the radial width W4 of the first and second arm inner edge C-chamfered portions 116a, 126a are set to be the same.

[0043] (Effects of this embodiment) 9 is a diagram comparing the rotation radius R1 of the first yoke 1 according to this embodiment with the rotation radius Rx of the conventional yoke X, and shows a plan view of the first arm portions 11, X1 of the first yoke 1 and the conventional yoke X. In the following explanation of this diagram, for the first yoke 1 and the conventional yoke X, the first arm portions 11, X1 will be illustrated as an example for convenience, but the same applies to the second arm portions 12, X2.

[0044] In the conventional yoke X, both outer edges in the rotation direction of the first arm portion X1 are formed with corners. That is, in the first arm portion X1 of the conventional yoke X, the arm outer surface 111b and the arm side surfaces 114a, 114b are connected at a substantially right angle. This increases the rotation radius Rx of the yoke X, which may cause interference with other in-vehicle components.

[0045] In this case, a possible method for reducing the rotation radius of the yoke X is to shorten the distance between the arm outer surface 111b of one arm portion (first arm portion X1) and the arm outer surface of the other arm portion (second arm portion not shown). However, in order to reduce the size of the yoke X in this way, it is necessary to newly design a die for forging the yoke X, which makes it difficult to contribute to reducing the manufacturing costs of the yoke X and the propeller shaft PS.

[0046] In contrast, the first yoke 1 according to this embodiment can solve the technical problems of the conventional yoke X by providing the following effects.

[0047] Specifically, the yoke (first and second yokes 1, 2) of the propeller shaft PS according to this embodiment includes a fixed portion (cylindrical base portion 10) fixed to a rotating shaft (first and second shaft members S1, S2), a pair of arm portions, a first arm portion 11 and a second arm portion 12, which extend from the fixed portion (cylindrical base portion 10) along an axial direction that is the direction of the rotation axis Z of the rotating shaft and face each other in a radial direction perpendicular to the axial direction with the rotation axis Z in between, a cross shaft 3 that supports the first arm portion 11 and the second arm portion 12, first and second arm base portions 111, 121 provided on the base end side of the first arm portion 11, and a pair of arm portions, a first arm portion 11 and a second arm portion 12, which are fixed to the rotating shaft (first and second shaft members S1, S2). The first and second arm tip portions 112, 122 are provided on the tip side of the arm bases 111, 121 and have a relatively thin wall compared to the first and second arm bases 111, 121 by having their radially inner portions recessed in a concave shape, and first and second arm outer edge chamfered portions 115, 125 are provided on the first arm portion 11 and the second arm portion 12 on the radially outer side of the first and second arm bases 111, 121 and extending in the axial direction along both circumferential edges of the rotation axis Z, and are recessed from the outside of the first and second arm bases 111, 121 toward the rotation axis Z.

[0048] In this manner, in this embodiment, first and second arm outer edge chamfers 115, 125 are formed along both outer side edges of the first and second arm base portions 111, 121, respectively. As a result, the rotation radius R1 of the first and second arm portions 11, 12 of the first yoke 1 according to this embodiment is smaller than the rotation radius Rx of the first and second arm portions X1, X2 of the conventional yoke X, as shown in Fig. 9. As a result, it is possible to reduce the rotation radius R1 of the first and second arm portions 11, 12 of the first yoke 1, and it is possible to improve the layout flexibility of the first yoke 1 and the propeller shaft PS using the same.

[0049] In addition, in this embodiment, the first and second arm outer edge chamfered portions 115, 125 have first and second arm outer edge C chamfered portions 115a, 125a which have a C-chamfered shape with a flat cutting surface, first and second arm outer edge R chamfered portions 115b, 125b which have an R-chamfered shape that smoothly connects the first and second arm outer edge C chamfered portions 115a, 125a to one circumferential side surface (arm side surface 114a) of the first and second arm base portions 111, 121, and first and second arm outer edge second R chamfered portions 115c, 125c which have an R-chamfered shape that smoothly connects the first and second arm outer edge C chamfered portions 115a, 125a to the other circumferential side surface (arm side surface 114b) of the first and second arm bases 111, 121.

[0050] In this way, in the first and second arm outer edge chamfered portions 115, 125, the first and second arm outer edge C chamfered portions 115a, 125a are connected by the first and second arm outer edge first R chamfered portions 115b, 125b and the first and second arm outer edge second R chamfered portions 115c, 125c, thereby preventing cornering of both circumferential edges of the first and second arm outer edge C chamfered portions 115a, 125a, and thereby preventing the occurrence of stress concentration due to such cornering.

[0051] In addition, since the first and second arm outer edge C-chamfered portions 115a, 125a are connected by the first and second arm outer edge first R-chamfered portions 115b, 125b and the first and second arm outer edge second R-chamfered portions 115c, 125c, the first yoke 1 can be easily demolded when forging it, thereby improving the formability of the first yoke 1.

[0052] In this embodiment, the first and second arm outer edge first R chamfered portions 115b, 125b and the first and second arm outer edge second R chamfered portions 115c, 125c are both configured with R chamfers having a radius of 3 mm.

[0053] By setting the R chamfer at the first and second arm outer edge chamfer portions 115, 125 to a large value, the rotation radius of the first and second arm portions 11, 12 can be reduced. However, this reduces the cross-sectional area of ​​the first and second arm portions 11, 12, which may result in a decrease in the strength of the first and second arm portions 11, 12.

[0054] Therefore, in this embodiment, the first R chamfered portions 115b, 125b on the outer edges of the first and second arms and the second R chamfered portions 115c, 125c on the outer edges of the first and second arms are configured with R chamfers having a radius of 3 mm, thereby making it possible to achieve both a reduction in the rotation radius R1 of the first and second arm portions 11, 12 and suppression of a decrease in strength of the first and second arm portions 11, 12.

[0055] In addition, in this embodiment, the propeller shaft yoke is characterized in that the angles θ1, θ2 between the circumferential side surfaces (arm side surfaces 114a, 114b) of the first arm portion 11 and the second arm portion 12 and the rotation axis Z are set to 3 degrees or less.

[0056] In this manner, the angles θ1, θ2 between the arm side surfaces 114a, 114b of the first and second arm portions 11, 12 and the rotation axis Z, so-called draft angles, are set to 3 degrees or less, thereby reducing the distance between the outer surfaces of the first and second arm portions 11, 12 (the distance between the outer surface of the first arm base portion 111 and the outer surface of the second arm base portion 121) and making it possible to reduce the rotation radius R1 of the first and second arm portions 11, 12. Furthermore, by reducing the distance between the outer surfaces of the first and second arm portions 11, 12, it is possible to ensure a larger bending angle of the first yoke 1, thereby improving the ease of assembling the propeller shaft PS to the vehicle.

[0057] On the other hand, if the angles θ1, θ2 between the arm side surfaces 114a, 114b of the first and second arm portions 11, 12 and the rotation axis Z, that is, the so-called draft angles, are set too small, it becomes difficult to remove the first yoke 1 from the die when forging it. Therefore, by setting the angles θ1, θ2 between the arm side surfaces 114a, 114b of the first and second arm portions 11, 12 and the rotation axis Z to 3 degrees or less, good removal from the die when forging the first yoke 1 can be ensured.

[0058] In this embodiment, the first and second arm tip portions 112, 122 have an elliptical shape whose radial length is shorter than its axial length.

[0059] In this way, by making the first and second arm tip portions 112, 122 elliptical in shape with the radial length L1 shorter than the axial length L2, the rotation radius R1 of the first and second arm portions 11, 12 can be reduced compared to when the first and second arm tip portions 112, 122 are made perfectly circular.

[0060] In addition, in this embodiment, the first arm portion 11 and the second arm portion 12 have first and second countersunk portions 110a, 120a at the outer ends of the first and second arm through holes 110, 120 into which the cross shaft 3 is inserted, and the first and second countersunk portions 110a, 120a are arranged so that they partially overlap with the first and second arm outer edge chamfered portions 115, 125 in the axial direction.

[0061] In this way, by providing a portion of the first and second countersunk portions 110a, 120a so as to overlap the first and second arm outer edge chamfered portions 115, 125, it is possible to remove the edge on the arm outer side surface 111b, 121b side of the first and second arm outer edge chamfered portions 115, 125 around the first and second arm through holes 110, 120 by forming the first and second countersunk portions 110a, 120a. This makes it possible to reduce the rotation radius R1 of the first and second arm portions 11, 12 by the amount removed by the first and second countersunk portions 110a, 120a.

[0062] (Modification) FIG. 10 is a diagram showing a modified example of a yoke of a propeller shaft according to the present invention, and corresponds to a cross-sectional view taken along line CC in FIG. 5, showing a transverse cross-sectional view of a first arm portion.

[0063] 10, in the yoke (first yoke 1) of the propeller shaft according to this embodiment, the arm outer side surfaces 111b, 121b of the first and second arm bases 111, 121 are formed by generally arc-shaped curved surfaces that bulge outward (radially outward). In other words, in this embodiment, the arm outer side surfaces 111b, 121b of the first and second arm bases 111, 121 are formed to bulge outward, thereby ensuring a cross-sectional area that is relatively larger than that of the first and second arm bases 111, 121 according to the first embodiment.

[0064] As described above, in this embodiment, the arm outer surfaces 111b, 121b of the first and second arm bases 111, 121 are formed as arc-shaped curved surfaces that bulge outward, thereby increasing the cross-sectional area of ​​the first and second arm bases 111, 121, and thereby improving the strength (rigidity) of the first and second arm bases 111, 121.

[0065] The present invention is not limited to the configurations and aspects exemplified in the above-described embodiments, and can be freely modified depending on the specifications and costs of the target application as long as the form can achieve the above-described effects of the present invention.

[0066] As a yoke for a propeller shaft based on the above-described embodiment, for example, the following configuration is conceivable.

[0067] That is, in one aspect, the propeller shaft yoke comprises a fixed portion fixed to a rotating shaft, a first arm portion and a second arm portion which are a pair of arm portions extending from the fixed portion along an axial direction that is the direction of the rotation axis of the rotating shaft and facing each other in a radial direction perpendicular to the axial direction across the rotation axis, a cross shaft which supports the first arm portion and the second arm portion, an arm base provided on the base end side of the first arm portion and the second arm portion, arm tip portions which are provided on the tip side of the arm base in the first arm portion and the second arm portion and are formed relatively thin relative to the arm base by having an inner portion in the radial direction recessed in a concave shape, and arm outer edge chamfer portions which are provided on the radial outside of the arm base in the first arm portion and the second arm portion and extend in the axial direction along both side edges in the circumferential direction of the rotation axis, and which are recessed from the outside of the arm base toward the rotation axis.

[0068] In a preferred embodiment of the propeller shaft yoke, the arm outer edge chamfered portion has an arm outer edge C-chamfered portion having a C-chamfered shape with a flat cutting surface, an arm outer edge first R-chamfered portion having an R-chamfered shape that smoothly connects the arm outer edge C-chamfered portion and one circumferential side surface of the arm base, and an arm outer edge second R-chamfered portion having an R-chamfered shape that smoothly connects the arm outer edge C-chamfered portion and the other circumferential side surface of the arm base.

[0069] In another preferred embodiment, in any one of the embodiments of the propeller shaft yoke, the first R chamfered portion on the outer edge of the arm and the second R chamfered portion on the outer edge of the arm are both formed by R chamfering with a radius of 3 mm.

[0070] In still another preferred embodiment, in any one of the embodiments of the propeller shaft yoke, the angle between the circumferential side surfaces of the first arm portion and the second arm portion and the rotation axis is set to 3 degrees or less.

[0071] In still another preferred aspect, in any one of the aspects of the propeller shaft yoke, the arm tip portion has an elliptical shape whose radial length is shorter than its axial length.

[0072] In still another preferred embodiment, in any one of the above-mentioned propeller shaft yoke embodiments, the arm base portion has an outer surface formed by an arc-shaped curved surface that bulges outward.

[0073] In still another preferred aspect, in any of the aspects of the propeller shaft yoke, the first arm portion and the second arm portion have a countersunk portion at an outer end of an arm through hole into which the cross shaft is inserted, and the countersunk portion is arranged so as to overlap a portion of the arm outer edge chamfered portion in the axial direction.

[0074] As a propeller shaft based on the above-described embodiment, for example, the following configuration is conceivable.

[0075] That is, in one embodiment, the propeller shaft is a propeller shaft including a shaft portion and a yoke, the yoke having a fixed portion fixed to a rotating shaft, a first arm portion and a second arm portion extending from the fixed portion along an axial direction that is the direction of the rotation axis of the rotating shaft and facing each other in a radial direction perpendicular to the axial direction across the rotation axis, a cross shaft supporting the first arm portion and the second arm portion, an arm base provided on the base end side of the first arm portion and the second arm portion, arm tip portions provided on the tip side of the arm base in the first arm portion and the second arm portion and formed relatively thin relative to the arm base by having an inner portion in the radial direction recessed in a concave shape, and arm outer edge chamfer portions provided in the first arm portion and the second arm portion radially outside the arm base and extending along both side edges in the circumferential direction of the rotation axis, and recessed from the outside of the arm base toward the rotation axis.

Claims

1. A yoke for a propeller shaft, A fixed portion fixed to a rotating shaft; a first arm portion and a second arm portion that extend from the fixed portion along an axial direction that is a direction of a rotation axis of the rotation shaft and are opposed to each other in a radial direction perpendicular to the axial direction with the rotation axis therebetween; a cross shaft that pivotally supports the first arm portion and the second arm portion; an arm base provided on a base end side of the first arm portion and the second arm portion; an arm tip portion provided on a tip side of the arm base portion in each of the first arm portion and the second arm portion, the arm tip portion being formed relatively thin relative to the arm base portion by having an inner portion in the radial direction recessed in a concave shape; arm inner edge chamfers extending along the axial direction on both side edges in a circumferential direction of the rotation axis on the radially inner side of the arm base of the first arm portion and the second arm portion; an arm outer edge chamfered portion provided on the radial outside of the arm base and along both side edges in the circumferential direction of the first arm portion and the second arm portion, the arm outer edge chamfered portion having a circumferential width larger than that of the arm inner edge chamfered portion, extending in the axial direction such that the circumferential width is generally constant, and recessed from the outside of the arm base toward the rotation axis; A yoke for a propeller shaft comprising:

2. 2. A yoke for a propeller shaft according to claim 1, a yoke for a propeller shaft, characterized in that the arm outer edge chamfered portion has a C-chamfered arm outer edge C-chamfered portion formed with a flat cutting surface, a first arm outer edge R-chamfered arm outer edge R-chamfered portion that smoothly connects the arm outer edge C-chamfered portion and one circumferential side surface of the arm base, and a second arm outer edge R-chamfered arm outer edge R-chamfered portion that smoothly connects the arm outer edge C-chamfered portion and the other circumferential side surface of the arm base.

3. 3. A yoke for a propeller shaft according to claim 2, A yoke for a propeller shaft, characterized in that the first R chamfered portion on the outer edge of the arm and the second R chamfered portion on the outer edge of the arm are both formed by R chamfering with a radius of 3 mm.

4. 2. A yoke for a propeller shaft according to claim 1, A yoke for a propeller shaft, characterized in that an angle between the circumferential side surfaces of the first arm portion and the second arm portion and the rotation axis is set to 3 degrees or less.

5. 2. A yoke for a propeller shaft according to claim 1, A yoke for a propeller shaft, wherein the arm base has an outer surface formed by an arc-shaped curved surface that bulges outward.

6. 2. A yoke for a propeller shaft according to claim 1, the first arm portion and the second arm portion have countersunk portions at outer ends of arm through holes into which the cross shaft is inserted, A yoke for a propeller shaft, characterized in that the countersunk portion is provided so as to overlap a portion of the arm outer edge chamfered portion in the axial direction.

7. A propeller shaft including a shaft portion and a yoke, The yoke is A fixed portion fixed to a rotating shaft; a first arm portion and a second arm portion that extend from the fixed portion along an axial direction that is a direction of a rotation axis of the rotation shaft and are opposed to each other in a radial direction perpendicular to the axial direction with the rotation axis therebetween; a cross shaft that pivotally supports the first arm portion and the second arm portion; an arm base provided on a base end side of the first arm portion and the second arm portion; an arm tip portion provided on a tip side of the arm base portion in each of the first arm portion and the second arm portion, the arm tip portion being formed relatively thin relative to the arm base portion by having an inner portion in the radial direction recessed in a concave shape; arm inner edge chamfers extending along the axial direction on both side edges in a circumferential direction of the rotation axis on the radially inner side of the arm base of the first arm portion and the second arm portion; an arm outer edge chamfered portion provided on the radial outside of the arm base and along both side edges in the circumferential direction of the first arm portion and the second arm portion, the arm outer edge chamfered portion having a circumferential width larger than that of the arm inner edge chamfered portion, extending in the axial direction such that the circumferential width is generally constant, and recessed from the outside of the arm base toward the rotation axis; A propeller shaft comprising:

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