WO1992001877A1

WO1992001877A1 - Differential gearing with face gears

Info

Publication number: WO1992001877A1
Application number: PCT/NL1990/000107
Authority: WO
Inventors: Martinus Hubertus Cuypers; Jan Mathijs Seroo
Original assignee: Crown Gear B.V.
Priority date: 1990-07-26
Filing date: 1990-07-26
Publication date: 1992-02-06

Abstract

A differential gearing which is equipped for placing between an ingoing shaft (3) and two outgoing shafts (16, 17) lying essentially in line with each other and at right angles to the ingoing shaft comprises a satellite housing (6) which can be driven by the ingoing shaft so that it rotates about a shaft running coaxially with the outgoing shafts, and in which in the axial direction on either side the ends of the outgoing shafts can be accommodated, two face gears (14, 15) which are situated in the axial direction on either side in the satellite housing and the teeth of which face each other, and which can be connected non-rotatably to the ends of the outgoing shafts accommodated in the satellite housing, and at least two satellite gears (11, 12) in the form of cylindrical gear wheels which are positioned inside the satellite housing and which each mesh with the two face gears and are mounted so that they rotate freely on a shaft (9) situated at right angles to the outgoing shafts and connected firmly to the satellite housing in the direction of rotation of the satellite housing. The two face gears (14, 15) situated inside the satellite housing are freely movable in the radial direction within certain limits relative to the satellite housing (6) and are supported by the satellite housing in the axial direction at the side facing away from the satellite gears (11, 12). The shafts (9) of the satellite gears lie at equal angular distances from each other in the direction of rotation of the satellite housing.

Description

Differential gearing with face gears

The present invention relates to a differential gearing, equipped for placing between an ingoing shaft and two outgoing shafts lying essentially in line with each other and at right angles to the ingoing shaft, comprising a satellite housing which can be driven by the ingoing shaft so that it rotates about a shaft running coaxially with the outgoing shafts, and in which in the axial direction on either side the ends of the outgoing shafts can be accommodated, two face gears which are situated in the axial direction on either side in the satellite housing and the teeth of which face each other, and which can be connected non-rotatably to the ends of the outgoing shafts accommodated in the satellite housing, and at least two satellite gears in the form of cylindrical gear wheels which are positioned inside the satellite housing and which each mesh with the two face gears and are mounted so that they rotate freely on a shaft situated at right angles to the outgoing shafts and connected firmly to the satellite housing in the direction of rotation of the satellite housing.

Such a differential gear is known from Dutch Patent Application 8,702,461 of Applicant, in which patent application it is proposed that the right angle transmissions in a differential gearing which was traditionally designed with bevel gears should be made with face gears which mesh with spur cylindrical gear wheels.

The present invention is based on the idea that the design of a differential gearing can be simplified further as a result of the use of face gears, so that a differential gearing can be manufactured even more simply and cheaply. This design simplification is obtained according to the invention through the fact that the two face gears situated inside the satellite housing can be moved freely in the radial direction within certain limits relative to the satellite housing and in the axial direction are supported by the satellite housing at the side facing away from the satellite gears, while the shafts of the satellite gears lie at equal angular distances from each other in the direction of rotation of the satellite housing. This ovability of the two face gears in the satellite housing is permissible, since no radial forces act on them, as would be the case with conventional bevel gears. Compared with the conventionally used bevel gear transmissions, in which accurate positioning of the meshing bevel gears is vitally important for proper working, with the design according to the present invention a very considerable simplification which requires considerably less accurate working operations and adjustments is obtained. At least three satellite gears are preferably used, which means that the face gears are centred automatically in the radial direction relative to the satellite gears.

A further simplification can also be obtained through the satellite gears being movable in the axial direction within certain limits relative to the satellite housing. Since an accurate positioning of the satellite gears relative to the two face gears is not important, there is no reason why the satellite gears should not be movable to a limited extent in the axial direction.

The invention will be explained in greater detail with reference to the drawing, in which:

Fig. 1 shows a schematic illustration of a differential gearing according to the invention;

Fig. 2 shows a practical embodiment of a differential gearing according to the invention for use in a lorry; Fig. 3 is a cross-section along the line III-III in Fig. 2.

The differential gearing shown in Fig. 1 comprises a housing 1, in which a drive shaft 3 is mounted by means of bearings 2, which shaft can be connected to a drive motor. The drive shaft 3 bears on its end a spur cylindrical gear 4 which meshes with a face gear 5 which is fixed to a satellite housing 6, fixed in the housing 1 by means of bearings 7 so that it can rotate about an axis 8.

The satellite housing contains a fixed satellite gear shaft 9, which rotates with the satellite housing in a plane 10 at right angles to the axis 8. Two satellite gears 11 and 12 which are designed as spur cylindrical gears are disposed so that they can rotate freely on the satellite gear shaft 9, which satellite gears 11 and 12 are held at a distance from each other by means of a distance sleeve 13 mounted loose on the satellite gear shaft 9. The two satellite gears 11 and 12 each mesh with two face gears 14, 15 disposed opposite each other, each face gear 14, 15 being connected non-rotatably by means of a spline to an outgoing shaft 16, 17 respectively. As can be seen from Fig. 1, the outgoing shafts 16 and 17, in the form of half- shafts, lie essentially in line and rotate about the same axis 8 as the satellite housing 6.

The two outgoing shafts 16 and 17 with the face gears 14, 15 connected thereto are not supported in the radial direction inside the satellite housing 6. The radial support can be omitted because the face gears 14, 15 with the corresponding shafts 16 and 17 are not loaded in the radial direction. In principle, the face gears 14 and 15 can thus move freely in the radial direction within certain limits. It will be clear that the shafts 16 and 17 are supported in the usual manner outside the housing 1 of the differential gearing.

The two face gears 14 and 15 are supported inside the satellite housing 6 only in the axial direction by means of sliding elements 18, 19, which are placed between the face gear in question and the inside surface of the satellite housing 6. These sliding elements 18, 19 preferably each comprise a number of annular thin plates which are fitted next to each other so that they can rotate freely about the appropriate wheel shaft. These annular plates, three o which are placed next to each other as an example in the drawing, can be made of any suitable material, which may or may not be provided with a wearproof layer. It is particular advantageous to use thin smooth rings of hardened steel for this.

The two satellite gears 11 and 12 are fitted on the satellite housing 9 so that they are freely rotatable and axially slidable. The two gears are held more or less in place by the loose distance sleeve 13, while sliding elements 20, 21 are fitted between these gears and the inside surface of the satellite housing 6. Like the sliding elements 18, 19, these sliding elements can be made of one or more thin annular plates, which could possibly be provided with a suitable wearproof surface with a low coefficient of friction. Hardened steel rings available on the market are preferably used for this. By means of this design, the satellite housing 9 used can be a suitably manufactured shaft with constant diameter, which contributes to a simple and cheap manufacture. The satellite gears 11 and 12 can thus slide to a limited extent in the axial direction along the shaft 9 between the sliding elements and the distance sleeve, while the distance sleeve itself is also slidable in the axial direction. This axial displacement is permissible through the use of face gears and has no effect on the proper functioning of the differential gearing.

Figs. 2 and 3 show a practical embodiment of a differential gearing according to the invention for use in a lorry.

The design of this differential gearing is in principle the same as that of Fig. 1. Corresponding parts are therefore indicated by the same reference numbers provided with an apostrophe.

The differential gearing of Figs. 2 and 3 has, however, four satellite gears 22, 23, 24 and 25 which, as in the differential gearing of Fig. 1, are designed as spur cylindrical gears. Each of the four satellite gears 22, 23, 24 and 25 is mounted so that it is freely rotatable on a satellite gear shaft 26, 27, 28 and 29 respectively. The satellite gear shafts 26-29 lie in the plane 10' at right angles to the axis 8' at an angle of 90^: relative to each other. The satellite gear shafts 26-29 are connected to each other at the side of the axis 8' by means of a connecting piece 30. The satellite gear shafts 26-29 and the connecting piece 30 together form a star-shaped satellite gear support 31.

The satellite housing 6' is made up of two halves 6a and 6b, which are connected to each other by means of bolts 32. The partial face of the satellite housing 6' coincides with the plane 10' .

The free ends of the satellite gear shafts 26-29 are accommodated in cylindrical holes in the satellite housing 6' which are formed in the abutting faces of the semi- cylindrical recesses formed by semi-cylindrical recesses facing each other and formed in the abutting faces of the two satellite housing halves 6a and 6b. The satellite gear support 31 is thus fixed to the satellite housing 6'.

The satellite gears 22-25 are mounted on the satellite gear shafts 26-29 by means of bearing sleeves which are confined in the axial direction between the connecting piece 30 and retaining rings.

Through the use of four satellite gears 26-29, the shafts of which are at an angle of 90' relative to each other, the face gears 14' and 15* are centred automatically in the radial direction relative to the satellite gears. The same effect could be achieved by using three satellite gears the shafts of which are at an angle of 120' relative to each other.

The differential gearing of Fig. 2 is designed as a so- called locking differential. By means of the devices indicated by 33 in Fig. 2, a locking sleeve 34 which is provided on the outside with a spline can engage in a complementary spline in the satellite housing 6, so that this sleeve 34 is connected non-rotatably to the satellite housing. On the inside the sleeve 34 is provided with the same internal spline as the face gear 14', so that the sleeve 34 is slidable along the external spline of an outgoing shaft inserted into that face gear 14', in particular a wheel shaft such as the shaft 16 in Fig. 1, the length of the part of the shaft provided with an external spline being a suitable length. The outgoing shaft (wheel shaft) can then be connected non-rotatably to the satellite housing 6.

Since lower accuracy standards are required, a differential gearing according to the invention is simpler and cheaper to manufacture than a known differential gearing, in which the face gears are supported in the radial direction in the satellite housing.

Claims

C L A I M S

1. Differential gearing, equipped for placing between an ingoing shaft and two outgoing shafts lying essentially in line with each other and at right angles to the ingoing shaft, comprising a satellite housing which can be driven by the ingoing shaft so that it rotates about a shaft running coaxially with the outgoing shafts, and in which in the axial direction on either side the ends of the outgoing shafts can be accommodated, two face gears which are situated in the axial direction on either side in the satellite housing and the teeth of which face each other, and which can be connected non-rotatably to the ends of the outgoing shafts accommodated in the satellite housing, and at least two satellite gears in the form of cylindrical gear wheels which are positioned inside the satellite housing and which each mesh with the two face gears and are mounted so that they rotate freely on a shaft situated at right angles to the outgoing shafts and connected firmly to the satellite housing in the direction of rotation of the satellite housing, characterized in that the two face gears (14, 15;

14', 15') situated inside the satellite housing can be moved freely in the radial direction within certain limits relative to the satellite housing (6; 6') and in the axial direction are supported by the satellite housing at the side facing away from the satellite gears (11, 12; 22-25), while the shafts (9; 26-29) of the satellite gears lie at equal angular distances from each other in the direction of rotation of the satellite housing.

2. Differential gear according to Claim 1, characterized in that at least three satellite gears (22-25) are situated inside the satellite housing (6').

3. Differential gear according to Claim 1, characterized in that the satellite gears (11, 12) are movable freely in the axial direction relative to the satellite housing (6) within certain limits.