GB2195734A - Drive means with safety interruption - Google Patents

Description

GB2195734A 1 SPECIFICATION of relatively compact construction, the clutch

still represents a compromise. In particular, Drive means with safety interruption limits are imposed on the minimisation of the stopping time due to the fact that the number The present invention relates to drive means, 70 of switching dogs or abutment dogs is depen especially for the working unit of an agricultu- dent on the number of rolling bodies guided in ral harvesting machine, for example the chaff- the clutch hub and dimensioned in accordance cutting unit of a field chaff cutter. Such a with the overload clutch torque. Moreover, the drive means may be present in the drive train stopping torque is transmitted by only one and, on the emergence of a foreign body in 75 switch pawl and only one abutment dog. This the harvest flow, receives a signal and there- has the result that on the one hand the switch upon interrupts and stops the drive in the pawl and the abutment dog and on the other shortest possible time. hand the bearing of the entire assembly are Safety devices for working units of agricul- very highly loaded by transverse forces, which tural harvesting machines are known in a 80 inevitably have negative influences on costs.

variety of constructions, for example in DD-PS The switch pawl and the abutment dog must, 144 347 there is disclosed a safety device for the purpose of avoidance of wear, be di which for the stopping of the feed system of mensioned to be correspondingly large in re a field chaff cutter utilises the reversing spect of the permissible area pressure of only clutches of the reversing gear for the forward 85 one contact place. It is also disadvantageous and reverse running of the feed system, both that a central shift clutch is required for stopp reversing clutches being engaged simultane- ing of the drive of the combined overload ously after the central shifting clutch has stopping unit in order to ensure the engaged switched the drive off. This arrangement does setting, which is necessary for the reversing not, however, provide such short stopping 90 of the feed system, of the overload clutch, times for the feed rollers of the feed system whereby high costs arise just as in the case as would be necessary for the relatively short of DD-PS 144 347.

feed systems frequently used nowadays. It is There is thus a need for safety drive means even more critical when the highest feed which may prevent damage of a driven unit speed is chosen for the purpose of the pro- 95 through prompt stopping of the unit and duction of long chaff, because the foreign which requires relatively little cost and compli body quickly reaches the chaff-cutting drum, cation. Such drive means, for example for a which continues to run at unreduced high rota- working unit of an agricultural harvesting ma tional speed and in some circumstances may chine, should preferably be able to stop feed be destroyed completely as well as cause 100 equipment for the unit, or both the equipment consequential damage to adjoining assemblies. and the unit, in the shortest possible time, as Moreover, it is disadvantageous that the newell as absorb the high forces from the cessity of a central shift clutch gives rise to stopping process free of transverse forces and high cost. with relatively low area pressures and ad- In DE-OS 3 344 043 there is disclosed a 105 ditionally manage without a central shift clutch safety device which in its basic construction in the drive train.

corresponds to that described in DE-OS 3 034 According to the present invention, there is 606, but due to appropriate constructional provided drive means comprising a drive shaft measures can additionally provide rapid stopp- rotatably mounted in a casing, a toothed ing. To achieve this several shift dogs or 110 wheel which is mounted on the shaft to be abutment dogs, which are distributed at equal rotatable relative thereto but secure against angular spacings around the outer circumferdisplacement axially thereof and which in ence of a shift ring and on the clutch flange at cludes a hub portion internally provided with a the output side, are provided and so angularly first plurality of clutch discs, a second plurality displaced one relative to the other that, after 115 of clutch discs mounted on the shaft to be pivoting-in of a fixedly located, rotatably rotatable therewith and drivably engageable by mounted switch pawl, at first a shift dog ef- the discs of the first plurality, a shift element fects separation of the output drive from the which is arranged coaxially on the shaft to be inpu t drive and an abutment dog suddenly displaceable axially thereof but secure against stops the output drive thereafter. Also ar- 120 rotation relative thereto and which is resiliently ranged on the outer ring of the clutch flange biassed to exert pressure at one axial end on at the drive input is a shift dog which axially the discs for driving interengagement thereof, so displaces the shift pawl that after switch- the shaft element being provided at its other ing-off of the drive by means of the control axial end with a face toothing, an arresting system of the machine, the engaged setting of 125 element arranged coaxially on the shaft and the overload clutch is again provided and re- fixed to the casing, the arresting element be versing of the intake elements is thereby ing provided with a second face toothing made possible. facing the first face toothing, and displacing Although such an overload clutch can itself means to displace the shaft element axially of take over the function of the rapid stop and is 130 the shaft and against said resilient bias to 1 - 2 GB2195734A 2 bring the face toothings into interengagement. same in that an equivalent force-locking clutch In a preferred embodiment, a driven toothed is inserted for the clutch coupling and an equi- wheel, which carries a hub occupied by outer valent shape-locking clutch analogously for the discs, is rotatably mounted and axially fixed end face coupling.

on one of the gear shafts of a gear disposed 70 It has proved to be expedient to arrange the in a drive train. The shaft is provided with entire safety device on the shaft which is in inner discs which are mounted thereon secure tended separately for the drive of the part, against rotation and which project between which is to be protected, of the working unit.

the outer discs. A shift element, which sits This would, in the example of the field chaff centrally on the shaft and is axially displaceacutter, be the gear shaft present merely for ble by means of a shift fork, bears at one end the drive of the feed rollers. Thus, only the against the inner and outer discs with a de- feed rollers and the drive parts up to that are fined contact pressure brought about by a stopped suddenly and the resulting torque spring, and at the other end is provided with peaks remain within limits.

a radial or face toothing. A flange bushing, 80 In order that a secure engagement of the which also sits centrally on the shaft, at one end face coupling is provided in all cases and end carries a radial or face toothing which so the build-up of torque during the stopping pro stands opposite the radial toothing at the shift cess starts only when the shift element has element that both can be brought into engage- attained its maximum axial minimum engage ment each with the other through displacement length, a locking ring, which is rotatable ment-of the shift element, the flange bushing through a defined amount, can be mounted on being firmly connected at its other end with the flange bushing. This locking ring pos the gear casing. As a result, three functions sesses a radial toothing with the same pitch are attained an overload protection and at the and the same modulus as the radial toothings same time he interruption of the drive being 90 of the shift element and the flange bushing.

attainable through the presence of the disc The pitch circle of its radial toothing lies in clutch, while stopping in the shortest time is the same plane as the pitch circle of the radial possible through the end face coupling. toothing of the flange bushing, the addenda, For the choice and arrangement of the kind however, projecting beyond those of the of clutch on the shaft, an important considera- 95 flange bushing by a small amount. The posi tion is that force-locking clutches have rela- tion of the radial toothings of the locking ring tively large sliding travel for only minimum and of the flange bushing in rotational direc shift travel and shape-locking clutches have tion one relative to the other is fixed in the large shift travel, but minimum loss travel in disengaged state by a pin, which is let into circumferential direction. 100 the flange bushing and engages into an elon- In the case of use of the drive means in an gate hole, extending in rotational direction, of agricultural harvesting machine, on recognition the locking ring. The pin and the locking ring of a metallic or non-metallic foreign body in are so connected with each other by a spring the harvest stream by recognition equipment, standing under tensile stress that, in this set a signal can be generated to set actuating 105 ting of the locking ring, the teeth of its radial equipment into motion. The actuating equip- toothing cover the regions of the radial tooth ment, by means of the shift fork, can displace ing of the flange bushing where, during en the shift element axially against the force of gagement, the attainment of a maximum axial the spring. Even at the start of movement of minimum engagement length of the radial the shift element, the disc clutch is opened 110 toothings of the shift element and of the and the drive is thereby interrupted. If the flange bushing would be impossible.

shift element is pushed further, the radial If engaging is to be done around the end toothing thereof engages into that of the face coupling, then initially there is addenda flange bushing firmly connected with the cas- abutment of the radial toothing of the shift ing and the drive of the feed equipment to the 115 element and of the locking ring. The entraining working unit is abruptly stopped. It is thereby torque arising in consequence of sliding fric ensured that the drive is initially switched off tion is greater than the rolling torque of the -gently by way of minimum shift travels of the bearing between the flange bushing and the disc clutch and the blocking of the feed equip- locking ring plus that of the torque caused ment takes place thereafter by way of the end 120 through the spring and produces a rotation of face coupling, whereby the entire stopping the locking ring by the amount of the length process takes place in shortest time. The saf- of the elongate hole. In this setting, the en ety drive means has advantages for re-en- gagement process starts with a maximum ax gagement of the drive after removal of the ial engagement length of the radial toothings foreign body, since it makes possible a gentle 125 of the shift element and of the flange bushing.

starting-up of the feed equipment, after the A convolute toothing, the angle of engage- removal of the mechanical arresting, by way ment of which is smaller than the friction cone of the -disc clutch, which affords advantages angle, is expediently chosen for all radial for the dimensioning thereof. The advantages toothings. Thereby, a large number of entrain are, of course, to be exploited exactly the 130 ing members and self- locking are achieved.

3 GB2195734A 3 This toothing can be produced economically, varied by means of a wheel group 23. A has a relatively low areal pressure due to the wheel pair 24 serves for reduction of rota large area in the case of engagement, and tional speed in order to obtain an optimum requires only relatively small shift travels for rotational speed for the safety device. A end face couplings. 70 toothed wheel 25 of the wheel pair 24 carries Advantages of safety drive means embody- outer discs 27 in a hub 26 and the shaft 19 ing the invention may be that the stopping carries inner discs 29 by way of the ring 28.

process proceeds in shortest possible time An axial contact pressure of the discs, re due to the large number of teeth in the radial quired for the transmission of torque from the toothings, whereby damage of the working 75 wheel 25 to the shaft 19, is exerted by unit of the harvesting machine due to foreign means of biassed springs 30 acting on a shift body ingress can be avoided even in the case element 33. If an overload of the feed rollers of high feed speed and short feed equipment 13 arises, the discs 27 slide relative to the During the stopping process, the safety device discs 29 and thus represent an overload pro is free of transverse force loading and the 80 tection. The resulting axial and radial forces in are& pressure in the teeth of the radial tooth- this case are taken up by a rolling bearing 3 1.

ings is small due to their multiplicity, for If a foreign body recognition device installed in which reason the cost for the safety device the chaff cutter recognises a foreign body in remains low. Moreover, the device has a dual the harvested stock, it generates a signal function, since it also acts as an overload pro- 85 which sets an actuating device (not shown) tection. Due to the interruption of drive before into motion, which by way of a shift fork 32 the stopping process, there is no need for a displaces the shift element 33 axially on the central shift clutch which is also advantageous shaft 19. Since the shift element 33 transmits in respect of cost. the force of the springs 30 end-on to the An embodiment of the present invention will 90 discs 27 and 29, there is already the start of now be more particularly described by way of a movement leading to interruption of the example with reference to the accompanying drive. On further displacement of the shift ele drawings, in which. ment 33, a radial toothing 34 thereof engages Fig. 1 is a schematic plan view of the drive into a radial toothing 35 of a flange bushing system of an automotive field shaft cutter 95 36, which is also arranged centrally around equipped with safety drive means embodying the shaft 19 and firmly connected with the the invention; and gear unit casing 37, and leads to instantane- Fig. 2 is a schematic sectional view of the ous standstill of the shaft 19.

drive means, in particular for the drive of the In order to exclude faulty switchings of the chaff-cutting unit. 100 kind that cause torque build-up before conclu- Referring now to the drawings there is sion of the engagement process, a locking shown in-Fig. 1 an agricultural chaff cutter 1 ring 39 is rotatably mounted by means of a equipped with a bevel wheel distributor gear bearing 38 on the bushing 36. At its end 4, the outputs of which are connected through face, the locking ring carries a radial toothing a belt drive 5 with a chaff-cutting drum 6 and 105 40 which has the same pitch and module as through a stepless belt gear 7 with a changethe radial toothings 34 and 35. Departing speed travel gearbox 8. The gear 4 is driven from this, however, is the tooth thickness by means of an articulated shaft 3 from an which is determined under consideration of all engine arranged longitudinally in the direction influencing magnitudes. The position of the ra of travel of the chaff cutter 1. Driven by 110 dial toothings 35 and 40 each relative to the means of a belt drive 9 from the input of the other is so fixed by means of a pin 41, an gear 4 is a gear unit 10, from which feed elongate hole 42 receiving the pin, and a rollers 13 as well as an articulated shaft 14 spring 43 that an immediate engagement of and a bevel wheel gear 15 of an adapter (not the shift element 33 into the radial toothings shown) are driven by way of an articulated 115 35 and 40 is possible only when the engage shaft 11 and a bevel wheel gear 12. ment process is concluded before the build-up The gear unit 10 comprises four, axially par- of the stopping torque. In the other case, allel shafts, namely an input shaft 16, an out- there is addendum abutment of the teeth of put shaft 17 for the drive of th e adapter, an the shift element 33 and of the locking ring intermediate shaft 18, and a gear shaft 19 for 120 39. Since the entraining torque arising from the drive of the feed rollers 13. Arranged on the sliding friction is greater than the rolling the input shaft 16 is a double clutch 20, torque brought about in the bearing 39 inclu which consists of two elements and which by sive of the torque caused by the spring 43, way of a wheel pair 21 drives the adapters as the result is entrainment of the locking ring 39 well as the feed rollers 13 in forward running 125 until the other end of the hole 42 abuts the as well as, by way of the wheel group 22, pin 41. Since the required association is given reverse running. This reversing operation is re- in this setting, there is thus conclusion of the quired for the elimination of clogging in the engagement process before the build-up of feed system. The rotational speed of the feed the stopping torque.

rollers 13 and thereby the chaff length can be 130 All radial toothings 34, 35 and 40 are exe- 4 GB2195734A 4 cuted as convolute toothings, the angle of en- first and second toothings would not be pos gagement of which is smaller than the friction sible during interengagement.

cone angle. This provides a large number of 6. Drive means as claimed in claim 5, entraining members and self-locking, as well wherein the angle of said angular range is as economical production. Tooth thickness 70 such that the locking ring and arresting ele- and gap width can be determined in depen- ment are relatively rotatable to dispose the dence on the angle of engagement, on the second and third face toothings in such a rela maximum circumferential speed and on the tionship that a maximum axial minimum en shifting speed. gagement length of the first and second 75 toothings is attained during interengagement.

Claims (5)

CLAIMS 7. Drive means substantially as hereinbefore

1. Safety rotary drive means comprising a described with reference to Fig. 2 of the ac- drive shaft rotatably mounted in a casing, a - companying drawings.

toothed wheel which is mounted on the shaft 8. An agricultural harvesting machine corn- to be rotatable relative thereto but secure 80 prising drive means as claimed in any one of against displacement axially thereof and which the preceding claims for driving a working unit includes a hub portion internally provided with of the machine.

a first plurality of clutch discs, a second plu- 9 A machine as claimed in claim 8, wherein rality of clutch discs mounted on the shaft to the drive shaft of the drive means is drivingly be rotatable therewith and disposed alternately 85 coupled and respective to a part, to be pro- between and drivably engageable by the discs tected, of the unit.

of the first plurality, a shift element which is 10. A machine as claimed in claim 8, arranged coaxially on the shaft to be displa- whe ' rein the machine is a chaff-cutter and the ceable axially thereof but secure against rota- unit is a chaff-cutting unit.

tion relative thereto and which is resiliently 90 11. A machine as claimed in any one of biassed to exert pressure at one axial end on claims 8 to 10 and substantially as hereinbe the discs for driving interengagement thereof, fore described with reference to Fig. 1 of the the shaft element being provided at its other accompanying drawings.

axial end with a face toothing, an arresting element arranged coaxially on the shaft and Published 1988 at The Patent Office, State House, 66171 High Holborn, London WC 1 R 4TP. Further copies may be obtained from fixed -to the casing, the arresting element be- The Patent Office, Sales Branch, StMary Cray, Orpington, Kent BR5 3RD.

-ing provided with a second face toothing Printed by Burgess & Son (Abingdon) Ltd. Con. 1187.

facing the first face toothing, and displacing means to displace the shaft element axially of the shaft and against said resilient bias to bring the face toothings into interengagement.

2. Drive means as claimed in claim 1, the displacing means comprising a shift fork.

3. Drive means as. claimed in either claim 1 or claim 2, comprising a locking ring which is mounted on the arresting element to be rota table relative thereto through a limited angular range and which is provided with a third face toothing having the same modulus and pitch Z11 as each of the first and second face tooth ings, the pitch circle of the third toothing be ing disposed in the same plane as that of the second toothing and the addendum circle of the third toothing being disposed outwardly of that of the second toothing.

4. Drive means as claimed in any one of the preceding claims, wherein each of the face toothings has a convolute form and an angle of action smaller than the friction cone angle.

5. Drive means as claimed in claim 3, wherein rotation of the locking ring relative to the arresting element is limited by a pin ar ranged on one and engaged -in a slot in the other and the arresting element and locking ring are intercoupled by spring means tending to maintain the second and third face tooth ings in such a relationship that the teeth of the third toothing cover the regions of the second toothing where attainment of a maxi- mum axial minimum engagement length of the 1