A differential-brake group for vehicle driving axles

Abstract: The invention relates to a differential-brake group for vehicle driving axles. On two supports (31) of a frame (3) the box (5) of a transmission (4) is rotatably mounted, with rotation freedom, the said transmission (4) being predisposed for the transmission of drive to two half-shafts (2). Two braking devices (6) are associated to the said walls (31), one for each half-shaft (2), which braking devices (6) form a single block with a sort of cover (32) peripherally equipped with a flange (33). In a seating made in the cover (32) the end part (8) of the drive input shaft into the differential is supported by means of bearings. The whole group is conformed in order to be insertable through an aperture (7) in an axle (1) and in order to be fixable to the said axle (1) by means of a flange (3).

Description: The invention relates to a differential-brake group for vehicle driving axles. Specifically, but not exclusively, the invention finds application in motor axles destined to equip, for example, vehicles of large dimensions. For such types of vehicles, the braking of the drive wheels is preferably made on the half-shafts that receive the drive from a differential and transmit it with or without a final velocity reduction, to the wheel hubs. Commonly used are oil-immersed disk brakes which can conveniently use the mass of lubricant present in the axle for the dissipation of the considerable quantity of thermal energy created during the braking action. The prior art embraces the use of disk brakes inserted as an integral part in the structure of the axle. In such cases, the axle is realised in more than one segment, usually three: two lateral segments which contain the half-shafts and one central segment which contains the differential group. The brakes are contained in autonomous segments which are mounted and solidly assembled between lateral segments and the central segment to form a single structure. In such conditions, obviously, the dismounting and the subsequent remounting of the brakes on the relative half-shafts necessarily brings about the mounting and the remounting of the axle in its segments. Remembering that the attachment points of the axle of the vehicle are situated at the lateral segments, the simple need to dismount the brakes for maintenance operations leads to the complete dismounting of the axle from the vehicle. The prior art also embraces axles realised in a single piece exhibiting two lateral apertures, one for each side of the axle, predisposed in such a way that an entire brake assembly can be introduced and thus also extracted, which brake assembly comprises a frame internally to which a device for the execution of the braking is predisposed. The assembly is fixed to the axle by means of an external flange. Such solutions, while solving the fundamental problem of permitting the realisation of the axle in a single piece, and thus enormously facilitating all the mounting and dismounting operations of the brakes, require the realisation, at the sides of the central part of the axle, of two openings which must have a specially designed conformation of the piece and thus also a certain mass which, if perfectly tolerable in large-sized vehicles, are less so in smaller ones. Further, the making of the two apertures by the side of the central aperture, which serves to connect the differential to the drive transmission shaft, requires the performing of sufficiently accurate working for each aperture. Document GB-A-2 237 081 (D1), which can be seen as the nearest prior art, discloses a differential-brake group according to the preamble of claim 1. Each brake has an actuator in the form of an annular piston 38 which is axially displaceable in an annular cylinder 39 cut in the support arch. Fluid is admitted into a chamber 40 behind the piston 38 via a drilling 41 and an hydraulic union 42. A bleed nipple 43 is also provided for each chamber 40. The present invention, as characterised in the claims that follow, proposes to obviate the above-mentioned prior-art inconvenients and drawbacks by providing a special application and configuration of some parts that become constituent parts of the driving axle, in particular of the differential and the brakes acting on the half-shafts, and which are engineered in such a way as not to require further apertures on the axle apart from the central aperture. Among the advantages offered by the invention, in addition to the constructional simplicity and the rapidity of the mounting and dismounting, it should be remembered that the invention also has the ability to render the functioning of the braking device insensitive to deformations, to which the axle in normal use, that is, under weight, is subject. Further advantages and characteristics of the present invention will better emerge from the detailed description that follows, made with reference to the accompanying drawings, which represent a preferred embodiment here illustrated in the form of a non-limiting example, and in which: Figure 1 shows a frontal view: Figure 2 shows a schematic section made according to line I-I of figure 1. With reference to the drawings, 1 denotes the body of a driving axle equipping a vehicle. The axle 1 is made in a single piece and exhibits a substantially symmetrical structure with respect to a median plane perpendicular to the axle itself, internally to which the half-shafts 2 are housed, the said half-shafts 2 being predisposed to transmit drive to the wheels. In their turn the half-shafts 2 are connected and receive the drive from a differential mechanism 4 which is contained and supported internally to a frame 3. The said frame 3 is equipped with two walls or elements having a support function 31, opposite between themselves, between which elements 31 the differential 4 box 5 is rotatably mounted with liberty of relative rotation. In particular, on the two walls 31 seatings 34 and 35 are arranged for the housing of a pair of conical-roller bearings 36 on which the box 5 is supported. A crown wheel 51 is fixed to the said box 5 which crown wheel 51 receives the drive from a cogged pinion 9 which is solidly constrained to the end part 8 of the drive shaft inputting to the differential 4. The end part 8 of the drive shaft is in its turn sealedly couple by means of bearings 10 and 11 to a seating 84 made in the body of a sort of cover, denoted by 32, bolted to the frame 3. Made on the cover 32 are two double supports 38, predisposed to allow the mounting of actuator cylinders for the control of the braking device and in particular for the performing of the normal braking and the emergency and hand-braking braking. Two braking devices 6 are directly associated to the support walls 31 at the externally-turned sides, which braking devices 6 are predisposed to couple with the respective half-shafts 2. The two braking devices 6 are solidly connected to form, together with the frame 3, a single compact block predisposed and conformed to be mountable and dismountable on the axle 1 by simple introduction (or extraction) according to a transversal direction to the axle of the half-shafts 2 themselves through a single collection chamber 7 made on the axle 1 itself. Each braking device 6 is of the oil-immersed disk type and comprises a plurality of coaxial disks composed of two series of disks 61 and 62 side-by-side and alternatingly arranged one series with the other. In particular, the disks 61 and 62 are coupled axially slidingly to the fixed structure 60 of the braking device 6, which is solid to the frame 3 and the disks 62 are coupled solidly in rotation, but axially slidingly, on the relative half-shaft 2 by means of the hub 16. A coaxial annular element 63 is couple on each support wall 31 by means of a coupling which uses, in the illustrated embodiment, a crown bearing 69, and is externally equipped with an external cylindrical cogging predisposed to mesh with a cogged sector 64 which is part of the device for the brake control activation. The coaxial annular element 63, equipped with the possibility of rotating limitedly in the two senses commanded by the cogged sector 64, is frontally coupled with a disk-pushing element 65 which is mobile in axial direction and is predisposed to operate on the plurality of disks 61 and 62. The coupling between the coaxial annual element 63 and the disk-pushing element 65 is made by means of ball-bearings 68 housed in ramps 66 and 67. The above-described known-type mechanism permits of transforming a rotation of pre-established entity of the coaxial annular element 63 into an axial movement of the disk-pushing element 65. In other words, the rotation of the cogged sector 64 produces the activating of the single braking device. The cogged sector 64 is mounted on a pivot 14 which is housed in special seating envisaged in the cover 32 and which exhibits an end located externally to and solidly connected to the activating lever 12. The solid connection of the entire block (formed by the frame 3, the cover 32 and all the other organs coupled on them, such as the differential box 5, the two braking devices 6 and the end part 8 of the input drive shaft) to the axle 1 is sealedly realised, by flange, on the edge of the collection chamber 7 by means of the flange 33 peripherally arranged all around the cover 32. The connection is made by means of screws 15. The entire said block can thus be mounted or dismounted on the axle 1 with a very simple introduction operation (or extraction operation in the case of dismounting) in the collection chamber 7 in transversal direction with respect to the longitudinal axis of the axle 1 itself. Naturally both the introduction and the extraction can happen only when the half-shafts 2 are not present (not being inserted on the axle 1) internally to the hubs 16 constrained in rotation to the disks. Once the whole block has been assembled away from the axle, it is mounted on the said axle 1, comprising the end part 8 of the shaft and the braking devices 6 for the two half-shafts 2, by means of a single and simple operation. The compact characteristics of the invention permit a simple and advantageous application on axles, and thus on small-dimension vehicles.

Claims: A differential-brake group for vehicle driving axles, comprising a frame (3) equipped with two opposite elements or support walls (31) , between which a box (5) of a differential (4) is comprised and rotatably supported with relative rotation freedom, which differential (4) is predisposed for the transmission of drive to two half-shafts (2) located parallel to the rotation axis of the said box (5) with respect to the said frame ; both opposite walls (31) with support function being directly associated at their external sides to two braking devices (6) singly equipped with means for coupling to respective half-shafts (2) as well as relative control organs; the said braking devices (6) being solidly connected, together with the frame (3), to form a single block predisposed and conformed to be mountable or dismountable on the said axle (1), by simple introduction or extraction, according to a transversal direction to the said half-shafts (2), through a single aperture (7) made on the axle (1) itself; means being envisaged to permit a correct centring and solid connection of the said whole block to the said axle (1), each said braking devices (6) being of the oil-immersed disk type and comprising at least a plurality of coaxial disks composed of two series of disks (61 and 62) side-by-side and arranged alternated one with the other; the disks (61) of the first series being coupled coaxially slidingly to the fixed structure (60) of the said braking device (6) solid with the said frame (3) and the disks (62) of the second series being rotatingly solidly coupled, but axially slidingly, with the interpositioning of a hub (16), to the relative half-shaft (2); characterised in that a coaxial annular element (63) is envisaged, rotatably coupled on each wall (31), which coaxial annular element (63) is activated to make limited rotations in the two senses by means of a cogged sector (64) and is frontally coupled with a disk-pushing element (65), mobile in axial direction, predisposed to operate on the said plurality of disks (61) and (62); the said annular element (63) being on one side frontally coupled with the said disk-pushing element (65) by means of ball-bearings (68) housed in ramps (66) and (67) and being coupled on the other side, with freedom of rotation on the corresponding wall (31) by means of a thrust bearing; the said control organs for the activating of two braking devices (6) being associated to a cover (32) of the frame (3) and comprise a pivot (14) which is solid to the said cogged sector (64) and which is activated to rotate about its own axis by an external lever (12). A group as in claim 1, characterised in that two double supports (38) are made on the cover (32), which double supports (38) are predisposed to permit the direct fixing of actuator cylinders for the execution of the service braking and the emergency and hand-braking operations.

Inventors: MAGNI GIORGIO, MAGNI, GIORGIO
Applicants: OMCI SPA, OMCI S.P.A. OFFICINE METALMECCANICHE COSTRUZIONI INDUSTRIALI
Application year: 1992
Main classification: B60T1
IPC codes: B60T1