A device for the protection of a transmission joint in agricultural vehicles

Abstract: A first casing (5) has the proximal end fixed to a ring (6) sliding into a groove in the disc (2) and the distal end bearing an extension (10) inwardly folded; the casing has a first part (7) covering the intermediate means (2) as well as the zone which connects the latter with the yoke (3) and a second part (8) covering said yoke as well as the end of the transmission shaft (4); the connection between said two parts (7, 8) is realized by a section (9) which is deformable under the action of the transmission shaft (4) inclining when the vehicle goes round a bend.

Description: The present invention concerns a device for the protection of a transmission joint in agricultural vehicles, more especially for a homokinetic joint that is known in the field as "wide-angle joint" and allows the transmission shaft to be inclined up to an angle of about 80° compared to the motor-shaft or the drive-shaft. The field of the invention is that of transmission means for agricultural vehicles and the related protection devices of the transmission means as a whole, and especially of the joints for such means. This field is subject to the European standards EN 1151, EN 292 and EN 294 that prescribe operating tests and safety criteria and for this reason the sale of these transmissions means is subject to the issuance of certificates by competent authorities. The prior art comprises: i) a so-called "non integral protection", or open protection, in which a single casing body protects the perimeter of the joint, but leaves an opening through which a foreign body may reach rotating parts (see for example the European Patent n° 0 154 216 held by the same applicant); if one considers that the foreign body might be a person's hand, it is clear why such a protection is dangerous; it is fitted into a perimetral groove of the disc between the two yokes of the coupling where it is held in position by chainlets; it is a conical piece with the greater aperture facing the transmission shaft so that there are no problems when the shaft inclines, for example when the tractor goes round a bend. ii) a so-called "semi-closed petal protection" comprising a main casing that covers the whole joint around the perimeter and an auxiliary casing that covers the end of the transmission shaft that connects to the joint; the space between the two casings, set at a certain distance from one another, allows relative movements between the same casings when the transmission shaft inclines and is closed by a series of plastic"petals" that have their external margins fastened within the main casing and the internal margins are loose but touch the auxiliary casing; if, on one hand, this solution offers a certain amount of protection and the possibility of high inclinations of the transmission shaft, on the other it has its main drawback the fact that, because the "petals" are elastic, they may bend even under a weak pressure allowing a foreign body to reach the rotating parts of the transmission means. Finally, document GB 2,235,271 is known that discloses a device protecting a wide angle joint for agricultural vehicles by a hollow guard partially covering the joint and a sliding ring mounted on the joint and axially movable in the guard, the guard clearing the joint by a distance determined by the sliding ring and the guard, at an axial end thereof inclined towards the joint, comprising a flexible convoluted tube covering the joint and joining the remainder of the guard at an angle which is contactable by the ring. As a limitations of the device disclosed by the above document, it is reported that an wide aperture is let between the proximal end of the guard and the joint so that the safety provisions required by national and international regulations are not satisfied. In the following description we shall define as - proximal connection means - or also - proximal yoke - the joint means connected to the motor shaft or to the drive-shaft (these shall both conventionally be defined as - motion shaft -); as - distal connection means - or also - distal yoke - the joint means connected to the transmission shaft; as - disc - or - intermediate means - the means that connects the two previously named connection means. Furthermore, the term - casing(s) - is intended as the part or parts of the protection device that, fastened around the joint in a certain way, is of tubular, cylindrical, conical or funnel shape, in order to continuously cover the entire perimeter of the joint or part of it and is conveniently spaced from it. Generally, these casings are conveniently made of deformable plastic materials or mixes of natural or synthetic rubbers. It is understood that the device may be suited to protecting both the motion shafts. Therefore we shall term - proximal end - that of any part connected to the motion shaft and - distal end - that of any part adjacent the transmission shaft. The invention overcomes the above stated drawbacks; it is a protection device comprising: a) a first casing that has its proximal end conventionally fixed to a ring slidingly engageable in a groove of the device central means, said casing has a first part for covering the central means and the connections between the central zone and the distal connection means and a second part for covering said distal connection means and the related end of the transmission shaft, the connection between said two parts being realized by means of a section that is able to elastically deform under the action of the transmission shaft and to incline compared to the motion shaft so that the second part inclines compared to the first part; b) a second casing, fixed to a ring slidingly engageable in a groove of the distal connecting means that extends from outside into the first casing, adjacent to the inside wall of the latter; and, as characterized by the claims, comprises a third casing fixed to the perimeter of the proximal end of the first casing in order to in use perimetrally cover the part of the proximal connection means connected to the intermediate means and that the distal end of the first casing bears an extension folded inwardly and towards the proximal part of the casing, until in use it is adjacent to the distal connection means The main advantage of the invention is that it offers a complete and safe protection against the accidental or intentional entry of a foreign body in the joint zone; the first casing effectively prevents the entry of a foreign body especially in the region of the connection between the intermediate connection means and the distal connection means, that is the most dangerous, while the second casing cooperates with the extension folded inwards from the distal end of the first casing to effectively prevent the entry of a foreign body in the region in which the distal connection means is connected to the end of the transmission shaft. The invention is explained in detail below with an example of embodiment and with reference to the attached drawings, in which: Fig. 1 is a longitudinal unit view partly sectioned, Fig. 2 is a first partly sectioned longitudinal view, Fig. 3 is a second partly sectioned longitudinal view, and Fig. 4 is a third partly sectioned longitudinal view. Figure 1 shows : the proximal yoke 1, solid with the motor shaft, not shown, connected to disc 2 and the distal yoke 3 solid to the transmission shaft 4 and a first casing 5 fixed to the ring 6 engaged so as to slide within a perimetral groove of the disc 2; this casing 5 is in a single piece and bears a first part 7 that covers disc 2 essentially up to the zone where the latter is connected to the distal yoke 3 and bears a second part 8 that covers the remaining part of the distal yoke 3 and the zone in which the latter connects to the transmission shaft 4; the connection between parts 7 and 8 of casing 5 is realized with the deformable Z shaped section 9 that allows the part 8 to incline compared to part 7 when the distal yoke 3 and the transmission shaft 4 incline compared to the motor shaft; extension 10 of casing 5 is folded towards the inside and towards the proximal part of the casing in order to collaborate with a second casing 11, fixed to a ring 12 slidingly engaged in a groove of the dital yoke 3, that is extended into the first casing ending with a radial extension 13 so that, even if a foreign body should pass the obstacle set by extension 10, the second casing with its extension 13 will avoid any contact with rotating parts; another purpose of the second casing 11 is to afford an adequate engagement seat to the pipe 15 that protects the transmission shaft 4 along its entire length; the third casing 14 is fixed to the external perimeter of the proximal end of the first casing in order to protect the connection zone between the proximal yoke 1 and disc 2. Fig. 2 shows another way to realize the deformable section 9; the casing 5 is a single piece of conveniently elastic plastic material; the deformable section has an S shape especially suited to the purpose; the apertures 16 on the proximal end of the casing serve to engage the latter on the ring 6, by means of appropriate extensions, not shown, that the latter bears in correspondance with the same apertures. Fig. 3 shows a part of the upper half of a casing 5 in one piece in order to illustrate yet another way to realize said deformable section 9 shaped like bellows. Fig. 4 shows part of the upper half of a casing 50 in order to illustrate yet another way to realize a deformable section 90 with a connecting element between the two parts 70 and 80 of the casing that is realized in two parts; these parts are joined by the pre-formed Neoprene S-shaped deformable section 90 fixed to their perimeter by means of rivets 18.

Claims: A protection device for a transmission joint for agricultural vehicles, the joint having a proximal connecting means, a distal connecting means (3) which is connected to a transmission shaft and an intermediate connecting means, the device comprising a first casing (5, 50) and a second casing (11), the first casing being conventionally fixed with its proximal end to a ring (6) slidingly engageable within a groove in the intermediate connecting means (2) and bearing a first part (7,70) for covering said intermediate means (2) and the connection zone between the latter and said distal means (3) and a second part (8, 80) for covering the distal connecting means (3) and the related end of the transmission shaft (4), the connection between said parts (7,70-8,80) being realized by means of a deformable section (9,90) that is able to deform under the action of the transmission shaft and to incline compared to the motion shaft in order that the second part of said casing inclines compared to the first part with the same angle as the transmission shaft; the second casing (11) being fixed to a ring (12) slidingly engageable in a groove in said distal means (3) and extending from outside into the first casing ; the device being characterized in that it comprises a third casing (14) fixed to the perimeter of the proximal end of the first casing (5, 50) in order to in use perimetrally cover the part of the proximal connecting means (1) connected to said intermediate means (2) and in that the distal end of the first casing bears an extension (10) folded inwardly and towards the proximal part of the casing until in use it is adjacent to the distal connecting means (3) A protection device according to claim 1 characterized in that the second casing (11) extends into the first casing (5, 50) until it is adjacent to the internal wall of the latter. A protection device according to claim 1 characterized in that the first casing (5) is in one piece and the deformable section (9) has a Z, an S or a bellows shape. A protection device according to claim 1 characterized in that the first casing (50) is of two parts (70, 80) facing one another, the facing perimeters of said parts being connected by the deformable section (90).

Inventors: BENZI VITO CARLO, BENZI, VITO CARLO
Applicants: BENZI & DI TERLIZZI, BENZI & DI TERLIZZI S.N.C.
Application year: 1997
Main classification: F16D3
IPC codes: A01B71, F16D3