WO1993021752A1

WO1993021752A1 - Protective bellows

Info

Publication number: WO1993021752A1
Application number: PCT/SE1993/000357
Authority: WO
Inventors: Lars Lindström; Torbjörn MORÉN; Olle NORÉN; Roger Hansson
Original assignee: Skogs- Och Lantbrukshälsan Ab
Priority date: 1992-04-24
Filing date: 1993-04-23
Publication date: 1993-11-11
Also published as: SE9201300L; NO943976D0; SE9201300D0; NO943976L; AU4274893A; SE470121B; EP0637905A1; FI944957A; FI944957A0

Abstract

Protective bellows (10) at the shaft end (2) of a rotating shaft comprising a connecting portion (14) attached to the annular bearing box of a stationary protective pipe (4) surrounding said shaft (1), said connecting portion (14) providing means (20) for detachably connecting a resilient bellows (11) to said connecting portion by means of a connecting ring (12) in order to achieve a complete covering of said shaft end (2). Through the device, the shaft end in its entirety will be protected in all situations, while permitting it to be detached for maintenance work by a single operation.

Description

PROTECTIVE BELLOWS

The present invention relates to a protective device for a cardan shaft of a transmission from a drive unit to a driven tool or machine, and particularly to a protective bellows, that covers the universal joint of such a cardan shaft. The protective bellows is meant to cooperate with a stationary protective pipe disposed around the rotating shaft, thereby providing an extension of the cardan shaft protection, that entirely covers the universal joints of the shaft ends up to the drive means or tool.

Particularly in the field of agriculture,there is often a need to drive connected units such as manure-spreaders, self-loading wagons or a bale machines etc. by means of the tractor power take-off. This need may be frequent enough to call for numerous connecting and disconnecting operations of such units or tools in the course of the working-day. In order to drive the tool or machine, the rotating movement is transmitted from the tractor power take-off to the tool or machine by means of a shaft, that is displaceable in its length direction and provided with a universal joint at its two ends. The universal joint at the end facing the tractor will be pushed onto the power take-off spline shaft and axially locked, usually by means of a spring-loaded locking pin, that engages with a tangential groove on the splined shaft.

The cardan shaft being coupled in this manner constitutes a serious risk of injuries, and demands are made in different places, e.g. by insurance companies and working environment orga¬ nizations, to prevent this risk by providing protective devices, that surround the rotating cardan shaft and the universal joint.

Several attempts have been made in order to prevent this risk of injury, the Swedish patent No. 218479 describing a funnel-shaped or cylindrically shaped universal joint protection, which, according to a first embodiment yields to axial forces by means of a step-by-step tapered, connecting portion between the protective funnel and a protective tube supporting said funnel above the cardan shaft, said connecting portion being made in a flexible material or radially slitted. In a second embodiment, in which the protective funnel is not made in a resilient material, the funnel is axially displaceable by means of a helical spring, that is disposed inside the protective funnel. The spring, one end of which is attached to the protective tube and the other end of which is attached to openings in the envelope surface at the base of the conical funnel, pushes the funnel over the cardan shaft.

The drawback related to these two protective funnels is primarily found in the fact that they do not provide a complete axial covering of the universal joint, whereby, in spite of the protection provided, the risk of injury remains. It is not possible to make the protective funnel of the first embodiment long enough to provide complete axial covering of the universal joint, since in this case the resilient portion does not permit sufficient axial displacement of the funnel to expose the universal joint to connection and maintenance, such as oiling. By its structure with the helical spring, the protective funnel of the second embodiment permits a greater amount of axial displacement, but it is obvious that if the funnel is made long enough to cover the whole universal joint up to the tractor, a gap would nevertheless occur at the radially outer side as the tractor turns.

Another drawback related to the protective funnels mentioned above is found in the fact that they do not suggest any means for a fast and simple exposure of the universal joint for maintenance work, this drawback also being relevant to a protective bellows described in the U.S. patent 4568313. This bellows is prefera¬ bly made of polyethylene and attached to the rotating universal joint by means of a number of wedges, that are disposed around the periphery of the bellows, that pass through the protective bellows and the protective tube surrounding said bellows, and that ride in a groove milled around one end of the universal joint. Thus, the wedges slide at the bottom of the groove as the universal joint rotates, and in order to prevent the protective bellows from taking part in the rotation, a chain is attached from one of the wedges to a fixed point on the tractor. This protective bellows is rigid, especially in cold weather, and necessitates great force in order to be pushed together whenever the cardan shaft and the universal joint are to be coupled to the power take-off, apart from it presenting this difficulty also when the universal joint is exposed for oiling. Due to the stiff¬ ness of this device, the great force, that is needed to make the universal joint accessible, possibly with a tool acting as a lever, causes the protective bellows to break in pieces.

An object of the present invention is to provide a protective bellows, that completely covers the rotating shaft end also as the tractor turns.

Another object of the invention is to provide a protective bellows, that can easily be axially pushed together in order to expose the universal joint for maintenance work, such as oiling.

Yet another object of the invention is to provide a fastening means cooperating with the bearing of the cardan shaft protective pipe and supporting the protective bellows of the present invention.

These objects will be achieved by a device of the type, that is disclosed in the characterizing part of the appended claim 1.

The invention will now be described closer in detail in con¬ nection with the appended drawings, in which

Fig. 1 schematically shows a universal joint and a portion of a cardan shaft with an axial section view of the device of the invention in a first position, Fig. 2 shows the device of fig. 1 in a second position.

Fig. 3 shows -the connecting portion of the protective bellows in two views t a cross sectional view and an end view,

Fig. 4 is a section through the cardan shaft showing an end view of the protective bellows, and

Fig. 5 shows the flexibility of the protective bellows in a drive position at an angular condition between the longitudinal axes of the drive vehicle and of the tool.

Fig 1. schematically shows a cardan shaft 1 with a universal joint 2, coupled in a known manner to the propeller slϊaft 3 in the power take-off (not shown) of the drive unit. The cardan shaft 1 is surrounded in a manner known per se by a protective pipe 4, which at its end presents an annular bearing box 5, which engages with an annular groove 6 on the shaft 7 of the joint yoke. The protective bellows 10 of the invention comprises a bellows 11, a connecting ring 12, a supporting ring 13 and a connecting portion 14. The bellows 11 is preferably made of a helical rubber hose with fabric or steel reinforcements. The connecting ring 12, to which the bellows 11 is attached, provides a centre opening IS providing a passage for the cardan shaft 1 and the protective pipe 4. The ring 12 further provides a number of axial grooves or openings 16, preferably three thereof, equally distributed along a circle inside the periphery of the ring (see also fig. 4). The openings 16 provide at one of their ends a circular enlargement. The supporting ring 13, to which the bellows 11 is also attached, protects the bellows end facing the tractor or-the tool and supports the bellows- against radial forces in order to maintain a circular cross section of the bellows 11. The connecting portion 14 is a rigidly designed cylindrical portion, which provides a centre opening 18 providing a passage for the cardan shaft 1 and the protective pipe 4. The opening 18 provides in its periphery a cross section profile 18' , which is adapted to the outer profile of the annular bearing box 5, by means of which the connecting portion 14 can be firmly attached to the bearing box and secured thereto by means of locking latches or lugs, which are well known to the specialist. The connecting portion 14 extends like a collar around the yoke end of the cardan shaft 1, which is thereby partly received in a conical or bowl-shaped connecting portion recess 19. The connecting portion 14 provides in its even surface, which is turned away from the universal joint 2, a number of pins 20, preferably three thereof, provided with a head, the pin head having a diametre permitting its passage through the circular enlargement 17 of the opening 16, the pin having a diametre permitting its passage along the narrower, groove-shaped portion of the opening 16.

Fig. 1 shows the protective bellows 10 in a first position where the bellows 11 is disconnected from the connecting portion 14 and axially displaced along the cardan shaft 1. The connecting portion 14 is, as described above, fixedly attached to the bearing box 5. In this first position of the protective bellows 11, the universal joint is entirely exposed and easily accessible for oiling of the joint cross through the lubricant nipple provided approximately at the arrow A at the centre of the joint cross. Normally, this oiling should take place after approxi¬ mately 8 working hours, thus constituting a frequently repeated operation.

Fig 2. shows the protective bellows 10 in a second position, where the bellows 11 is connected at the connecting portion and entirely covers the universal joint 2. Since the bellows 11 is longer than is the distance between the casting at the power take-off and the position of the connecting ring 12 at the connecting portion 14 in the coupled position, the bellows will rest resiliently against the casting with an axially directed force. In this respect, the bellows 11 is dimensioned so that its length will be sufficient to maintain its radially outer portion of the supporting ring 13 in contact with the casting (see Fig. 5), even when the tractor is turned or driven on broken ground. By a suitable choice of material in the bellows 11 as above, it will be easy to push it together far enough to reach the locking pin 8 when disconnecting the cardan shaft.

The connecting portion 14, that is shown schematically both in a cross section view and in an end view in fig. 3, is made in an impact and temperature resistant material, such as nylon. In this respect, the profile 18' of the opening 18 is given a shape that is adapted to the outer shape of the bearing box 5. In an alternate embodiment, the bearing box 5 is integrated with the connecting portion 14, protective pipe 4 attachments being formed in the connecting portion. In the flat surface of the connecting portion 14, which surface is turned away from the universal joint 2, an appropriate number of pins 20, corresponding to the number of openings 16 and preferably being three, provided with a head are attached in the connecting ring 12. Through the pins 20 and the openings 16 a bayonet-type coupling is provided for the protective bellows 10.

Fig. 4 shows, in an end-view with a cut through the cardan shaft 1, the way the bellows 11 is connected to the connecting portion 14 by inserting the pins-20 in the openings 16, initially through the circular enlargements 17 and then, through rotating the bellows 11 and the connecting ring 12 in the direction of the arrow B, along the openings 16 to the ends opposite the enlar¬ gements. The arrow C illustrates the rotational direction of the cardan shaft when driven, making it apparent that the bayonet coupling in fig.4 remains locked when co-rotated. The protective bellows 10 is prevented in a conventional manner from rotating with the cardan shaft by means of a (not shown) detachable chain, attached between the tractor/tool and the connecting ring 12.

With the protective bellows 10 as described above, a close- fitting cover at the cardan shaft 1, the cardan shaft end 2 and the power take-off shaf 3, sealingly resting against the casting or the like, is provided at the tractor or tool. Through the choice of a helical rubber hose with steel wire reinforcements and through overdimensioning the length thereof, a sealing engagement will be achieved even in the sharpest practical turning manoeuvre. The resiliency of the bellows permits, in spite of its length, that it be easily compressible for access to the cardan shaft end, and the bayonet-type quick coupling means a quick and easy exposure of the cardan shaft end for maintenance work.

The example above describes one embodiment of the invention, which simply discloses its basic concept. Without deviating from the scope of invention as stated in the claims, it is easy for the man, skilled in the art, to implement the invention in em¬ bodiments that will be advantageous, both aestethically and erg- onomically, production-wise and durability-wise, in relation to the shown embodiment.

Claims

1. Protective device at the shaft end (2) of a rotating cardan shaft (1), comprising a resilient bellows (11), a connecting ring (12) with a centre opening (15) and axial grooves or openings (16, 17) fixed at one end of said bellow, a supporting ring (13) fixed at the other end of said bellow, a connecting portion (14) with a centre opening (8) and connecting means (20), as well as a protective pipe (4) formed with an annular bearing box (5), which engages with an annular groove (6) on the cardan shaft (1), characterized in that said connecting portion (14) is attached to the cardan shaft side of said shaft end (2) by presenting in its centre opening (18) a profile (18¹), by means of which said connecting portion is in contact with said bearing box (5) and attaches thereto, in that the bellows (11) due to its length and resiliency under pressure contacts the wall at the power take-off of the drive device or the driven device by detachably connecting the connecting ring (12) through engagement between said grooves (16, 17) and the connecting means (20) to the connecting portion, and in that said protective device being attached in this manner makes the shaft end (2) accessible on one hand through compres¬ sion of the bellows (11) towards the shaft end (1) without disconnecting the connecting ring (12) from the connecting portion (14), on the other through the axial displacement of said bellows (11) over said shaft end (2) after the disconnecting of said connecting ring (12) from said connecting portion (14) for a total exposure of said shaft end (2).

2. Protective bellows according to claim 1, characterized in that said bearing box (5) is integrated with said connecting portion (14).

3. Protective bellows according to claim 1, characterized in that said connecting means (20) comprises pins (20), each provided with a head, said pins (20) constituting in cooperation with said grooves or openings (16, 17) of said connecting ring a bayonet-type quick coupling, which is secured in a rotational direction (B) opposed to the rotational direction (C) of said cardan shaft (1).

4. Protective bellows according to any of the preceding claims, characterized in that said bellows (11) is a helical rubber hose with steel wire reinforcements, or the like.