GB2054100A

GB2054100A - Splined coupling

Info

Publication number: GB2054100A
Application number: GB8021152A
Authority: GB
Original assignee: Nissan Motor Co Ltd
Current assignee: Nissan Motor Co Ltd
Priority date: 1979-07-25
Filing date: 1980-06-27
Publication date: 1981-02-11
Also published as: FR2462609A1; AU5906080A; AU524377B2; DE3022958A1; JPS5618121A; JPS6218770B2; IT8049250A0

Abstract

A shaft (1) has a spline groove (4) having sidewalls (5), and a surrounding rotary member (6) has a complementary tooth (7) in sliding engagement within the groove (4), such that it is slidable between a first position (shown in hard lines) and a second position (shown in broken lines) when it is not rotating. The groove sidewall (5) is provided with a projecting portion (42) which prevents the tooth (7) from sliding axially between the first and second positions while tangential forces (16, 17) are being exerted during transmission of torque between the shaft and member (6). When torque is no longer applied, tooth (7) becomes free to ride up and over the projection (42) in axial movement along the shaft. <IMAGE>

Description

SPECIFICATION Splined coupling The present invention relates generally to a splined coupling for transferring torque from a splined shaft to a mating splined gear, or viceversa, and more specifically to a splined coupling having means for selectively preventing axial movement of the gear relative to the splined shaft.

Spline couplings have been used extensively in various automotive vehicle transmissions and other gear mechanisms for transmitting torque. In order to vary the rotational speed, and thus the torque, through a gear mechanism, various gears are splined to a splined transmission shaft, thereby enabling the gears to, individually and independently, slide axially on the shaft to selectively engage other gears having different ratios of teeth, thereby selectively regulating the rotational speed, and thus the torque, of a transmission or gear box output shaft relative the rotational speed of the input shaft. The splined coupling permits the gear to slide axially on the gear shaft while maintaining contact between the gear and shaft to effectively transmit torque therethrough.

In the event the shaft axis and the splines are misaligned, the gear teeth and gear splines are misaligned or the. planes of the various gear teeth not perfectly parallel to the axis of rotation of the gear and/or splined shaft, when the gear teeth are meshed with those of a second gear, and a force is created tending to move the gear axially along the splined shaft. The problems inherent when this occurs are obvious.

The splined coupling of the present invention comprises a cylindrical rotating member having a spline formed therein, said spline including a sidewall; and a wheel member mounted on said cylindrical rotating member in axially sliding engagement therewith, said wheel member including a tooth for meshing with said cylindrical rotating member spline to enable said cylindrical rotating member and said wheel member to rotate together about the axis of said cylindrical rotating member, said coupling including retaining means formed therewith for selectively preventing axial movement of said wheel member relative to said cylindrical rotating member.

Preferably this retaining means takes the form of a boss or raised section, integrally formed with the sidewall of the cylindrical rotating member, to retain the tooth of a wheel member with the cylindrical rotating member so long as torque is applied to either the cylindrical rotating member or the wheel member. Applying torque creates opposing forces at the spline sidewall/gear tooth interface to urge the tooth against the sidewall and prevent axial movement of the wheel member over the spline boss, thereby retaining the wheel member in position.

In the accompanying drawings:- Fig. 1 is a vertical longitudinal section view of a conventional splined torque transmitting shaft, and a gear slidable thereon, also shown in section; Fig. 2 is a vertical sectional view taken along the line A-A of Fig. 1; Fig. 3 is a horizontal sectional view of a conventional splined coupling taken along the line B-B of Fig. 1; Fig. 4 is a vertical sectional view of a conventional synchromesh mechanism used in an automotive power transmission; Fig. 5 is a diagrammatic view illustrating a variation of the meshing gear and sleeve teeth of the synchromesh mechanism of Fig. 4; Fig. 6 is a horizontal sectional view similar to Fig. 3 but illustrating a preferred embodiment of the splined coupling of the present invention;; Fig. 7-is a horizontal sectional view similar to Figs. 3 and 6 but illustrating a second embodiment of the splined coupling of the present invention; Fig. 8 is a diagrammatic view similar to Fig. 5 but illustrating a third embodiment of the splined coupling of the present invention; and Fig. 9 is a horizontal sectional view similar to Figs. 3, 6 and 7 but illustrating a fourth embodiment of the splined coupling of the present invention.

To facilitate an understanding the present invention, a brief reference will be made to conventional splined couplings, depicted in Figs.

1-5. Referring to Fig. 1, a conventional splined shaft or other cylindrical rotating member 1 is shown having an access of rotation 2.

The shaft 1 is provided with a plurality of longitudinally extending teeth 3, defining a plurality of shaft splines 4 having sidewalls 5. A gear 6 is positioned about the splined shaft 1 for rotational movement therewith. The gear 6 includes a plurality of internal teeth 7, defining a plurality of gear splines 8, likewise including sidewalls 9. The gear shown in Fig. 1 also includes an annular fork recess 10 adapted to receive a fork (not shown) for selectively positioning the gear 6 along the shaft 1. The gear 6 also includes external teeth 11 for meshing with a gear 1 2 for transmitting torque from the shaft axis of rotation 2 to the meshing gear axis of rotation 1 3.

Fig. 3 illustrates, in greater detail, the engagement of the gear 6 about the splined shaft 1. With the internal teeth 7 positioned as shown in Figs. 1 and 3, and torque is applied to either the shaft 1 or gear 6, first and second normal forces, illustrated by respective arrows 1 6 and 17, are generated to cause rotation of the gear and shaft about the rotational axis 2. Under ideal circumstances, these are the only forces generated between the teeth 7 and spline 4 by rotation about the axis 2. However, errors in machining the splined shaft, the gear, or misalignment of pressure centers of the meshing teeth of the gear 6 and the gear 12, result in generating either first of second tangential forces, illustrated by respective arrows 14 and 1 5.

Frequently the magnitude of these tangential forces is sufficient to overcome the shear force between the meshing gears and the splined shaft tending to retain the gear 6 in position as shown in Fig. 1. When this occurs, the gear 6 is urged axially along the shaft 1 in either direction, depending on the direction of rotation of the gear and splined shaft.

Fig. 4 illustrates a conventional servo type synchromesh mechanism for synchronizing meshing gears in an automotive vehicle power transmission. A coupling sleeve 21 slides axially along a synchronizing hub 22 toward a clutch gear 23. A synchronizing ring 24 aligns the coupling sleeve 21 with the clutch gear 23 to enable the sleeve and gear to mesh together to establish rotational movement between a gear 25 and the rotating shaft 26.

Fig. 5 illustrates one method of designing clutch gear teeth and coupling sleeve teeth to prevent the coupling sleeve 21 from separating from the clutch gear 23 upon application of either of the aforementioned tangential forces, 14 or 1 5.

Clutch gear teeth 27 are formed with tapered surfaces 27a designed to engage mating tapered surfaces 28a of the coupling sleeve teeth 28 to thereby retain the coupling sleeve and clutch gear in uniform rotational movement about the shaft 26. Although the tapered teeth arrangement shown in Fig. 5 is adequate to accomplish its purpose of retaining the splined clutch gear in position with respect to the coupling sleeve, it will be obvious to those skilled in the art that an extremely intricate machining process is involved in manufacturing the gear and coupling sleeve teeth. This, of course, is quite time consuming and expensive.

In view of the above description of splined couplings, reference is now made to Figs. 6 to 9, and more specifically to Fig. 6, wherein a preferred embodiment of the splined coupling of the present invention is illustrated by the numeral 40. It comprises the splined shaft 1, having splines 4 each defined by the sidewalls 5. Internal gear teeth 7 mesh with the splines 4 as in the splined coupling shown in Fig. 1. However, the splined coupling 40 of the present invention incorporates means 42 integrally formed with the spline sidewalls 5 for retaining the gear teeth in position and preventing axial movement thereof in response to extraneous tangential forces 1 5 when torque is applied to either the splined shaft or the gear 6. In the preferred embodiment, this retaining means 42 takes the form of a boss, or raised section, integrally formed with the sidewall 5.In the embodiment shown in Fig. 6, two bosses are shown positioned opposite each other and formed in opposite parallel sidewalls 5 of each spline 4.

As is apparent to those skilled in the art, one boss will suffice for the purposes of the invention depending on the direction of rotation of the gear and splined shaft, and upon the particular function of the transmission or gear box utilizing the splined coupling of the present invention.

As shown in Figs. 6 to 8, a distance dseparates the tips of the respective bosses. This distance d, obviously must be greater than the thickness t of the individual gear internal teeth 7 to enable the gear teeth to slide freely along the shaft splines 4 as desired (i.e., to enable the gear teeth 7 to pass between the bosses 42 when there are no opposing normal forces 1 6 and 1 7 acting between the gear teeth and the spline sidewalls 5 as a result of torque applied to either the splined shaft 1 or the gear 6).

The sidewall boss 42 functions to retain the gear internal teeth 7 in position as shown in Fig. 6 so long as first and second normal forces 1 6 and 17 exist. When torque. is no longer applied to either the splined shaft 1 or the gear 6, the opposing forces 1 6 and 1 7 disappear and the gear internal teeth 7 may easily slide axially within the shaft splines 4 to a position designated by the phantom gear shown in Fig. 6.

Those skilled in the art will readily appreciate the funneling effect of the gear teeth retaining spline boss 42 of the present invention shown in Fig. 6. The tapered surface of each boss 42 acts to guide the gear tooth 7 through the channel defined by the tips of the respective bosses 42 so long as there are not sufficiently strong opposing normal forces 1 6 and 1 7 acting between the gear internal teeth and the splined shaft sidewalls.

Fig. 7 shows a slight variation of the present invention, incorporating a plurality of pairs of longitudinally spaced opposed teeth retaining spiine bosses 42. The construction and function of the spline bosses shown in Fig. 7 are identical to those shown in Fig. 6; however, Fig. 7 illustrates that a number of the gear retaining bosses of the present invention may be spaced within a single spline 4 to selectively retain the internal gear teeth 7 in each of a plurality of functional positions.

In addition to retaining the gear 6 properly in position about the splined shaft 1, the tapered bosses 42 of the present invention also have a centering effect to align the gear directly between a pair of axially spaced bosses upon an application of torque to the gear or shaft. Torque applied will create the normal forces, 1 6 and 17, causing a misaligned gear 6 to engage the boss tapered surface and be urged in a direction therefrom toward a centering position between the pair of axially spaced bosses.

Fig. 8 shows another embodiment of the present invention incorporated into a servo type synchromesh mechanism. The synchronizing hub teeth 50 mesh with the coupling sleeve teeth 51 as in the embodiment shown in Fig. 5. The coupling sleeve teeth 51 also engage the clutch gear teeth 52 in order to transfer torque from the coupling sleeve to the clutch gear, or vice versa.

As in the embodiments shown in Figs. 6 and 7, so long as a torque is applied to either the coupling sleeve or the clutch gear 52, resulting in normal forces analogous to the forces 1 6 and 17, gear teeth retaining bosses 53 function to retain the coupling sleeve teeth 51 in position as shown in Fig. 8. Upon the interruption of the torque applied to either the coupling sleeve or the clutch gear, the opposing normal forces disappear, enabling the coupling sleeve teeth 51 to be shifted axially to the left as shown in Fig. 8 over the gear teeth retaining bosses 53 and along the synchronizing hub teeth 50.

While the retaining means 42 have been shown and described as being projecting bosses formed on the sidewall surfaces 5 of the shaft splines 4, it will be obvious to those skilled in the art that the bosses may be formed on the mating gear teeth sidewalls 9, as shown at 62 in Fig. 9. In this case, however, it is necessary to additionally form mating recesses 64 in the shaft spline sidewalls 5 thereby enabling a more precise positioning of the gear upon the splined shaft.

Claims

1. A splined coupling comprising: a) a cylindrical rotating member having a spline formed therein, said spline including a sidewall; and (b) a wheel member mounted on said cylindrical rotating member in axially sliding engagement therewith, said wheel member including a tooth for meshing with said cylindrical rotating member spline to enable said cylindrical rotating member and said wheel member to rotate together about the axis of said cylindrical rotating member, said coupling including retaining means formed therewith for selectively preventing axial movement of said wheel member relative to said cylindrical rotating member.

2. A splined coupling comprising: (a) a cylindrical rotating member having a plurality of splines formed therein, each of said splines including a sidewall; and (b) a wheel member mounted on said cylindrical rotating member in axially sliding engagement therewith, said wheel member including a plurality of teeth, each of which engages respective said cyllindrical rotating member splines to enable said cylindrical rotating member and said wheel member to rotate together about the axis of said cylindrical rotating member, said coupling including retaining means formed therewith for selectively preventing axial movement of said wheel member relative to said cylindrical rotating member.

3. A splined couping as set forth in claim 1,2 or 3, wherein said wheel member includes a plurality of circumferential, spaced teeth.

4. A splined coupling as set forth in any of claims 1 to 3, further comprising one or more retaining means formed therewith for selectively retaining said wheel member in each of a plurality of selected axial locations about said cylindrical rotating member.

5. A splined coupling as set forth in claim 4, wherein the, or each retaining means comprises a boss formed with said cylindrical rotating member spline sidewall.

6. A splined coupling as set forth in claim 4, wherein said retaining means comprises a boss formed with said wheel member tooth and a mating recess formed with said cylindrical rotating member spline sidewall selectively engaging each other for selectively preventing axial movement of said wheel member relative to said cylindrical rotating member.

7. A splined coupling comprising: (a) a wheel member having i) a concentric bore therethrough, ii) a plurality of circumferential, spaced gear teeth, and iii) a plurality of splines within said bore, each of said splines including a sidewall; and (b) a splined shaft having i) a plurality of splines each having a sidewall for meshing with said wheel member splines to enable said shaft and said wheel member to rotate together about the axis of said shaft, and ii) a plurality of retaining bosses formed with respective said sidewalls of each of said splines and located radially in a plane transverse to said shaft axis for selectively retaining said wheel member in a specified axial location about said shaft, so long as sufficient opposed torques are applied to said wheel member and said spline cylindrical rotating member, respectively.

8. A splined coupling, substantially as hereinbefore described with reference to and illustrated in Fig. 6, or Fig. 7, or Fig. 8, or Fig. 9 of the accompanying drawings.