GB2162281A

GB2162281A - Gearing mechanism for converting rotary into reciprocating motion

Info

Publication number: GB2162281A
Application number: GB8518493A
Authority: GB
Inventors: Ii Gustav Schumacher; Guenter Schumacher
Original assignee: Individual
Current assignee: Individual
Priority date: 1984-07-26
Filing date: 1985-07-22
Publication date: 1986-01-29
Also published as: FR2568090A1; DE3427503A1; DK338785D0; DK338785A; GB8518493D0

Abstract

A drive gear for reciprocating reaping blades of harvesting machines having a rotor 20 rotating in a housing 23, a geared planet wheel 25 mounted on this rotor, rolling within a stationary internal gear rim 31 and being connected to a crank, the diameter of the planet wheel coinciding with the radius of the internal gear rim and the radius of the planet wheel coinciding with the radius of the crank, wherein in order to achieve a compact arrangement of the structural components, the planet wheel (25) is integrally designed as a crank or as a holder for a crank or a crank bearing. <IMAGE>

Description

SPECIFICATION Drive gear for reaping blades of harvesting machines The invention relates to a drive gear for reciprocating reaping blades of harvesting machines.

Blade drives of this type are produced in a very wide variety of constructions. The simplest form is a crank, which converts rotational movement into oscillating movement via a connecting rod or drive rod. For reasons of space, this form cannot be used in selfpropelled working machines, such as a combine harvester.

To permit a less bulky construction, the crank drive is often turned through 90 via an oscillating crank.

Other designs give preference to swashplate bearings, whose wobbling movement generates oscillating movements via a swashplate shaft reciprocating at right angles to the axis of wobble, and a lever attached in turn to the latter. All these designs suffer from the disadvantage that the transmission of force to the reaping blade is not precisely linear. In the types of drive described, each oscillating crank and each lever describes a radial movement about its centre of rotation. The longer the construction of the lever in each case, the smaller is the radial movement, but the greater is the torque which acts on the centre of rotation when the blade is stressed. The smaller the radial movement, the longer the lever arm. The longer the lever arm, the greater the torque. The greater the torque, the greater the necessary strength and weight of the drive elements.These in turn are the more expensive, the stronger their construction, and require more weight, space and material.

Drives of this type are from the outset suitable only for the shortest possible stroke of the reaping blade.

A far more advantageous possibility is offered by a drive gear resembling a planetary gear, wherein a planet wheel, which is mounted on a rotor, rolls within a stationary internal gear rim, a crank being linked with the planet wheel. In this arrangement, the radius of the internal gear rim and the diameter of the pitch circle of the planet wheel are of equal magnitude. The radius of the pitch circle of the planet wheel is in turn equal to the radius of the crank which is actively linked to the planet wheel.

As a result of this structural design, the crank pin executes an absolutely linear reciprocating movement with each rotation of the rotor. This linear movement thus corresponds precisely to the diameter of the pitch circle of the internal gear rim and/or to twice the diameter of the planet wheel and/or to four times the radius of the crank connected to the planet wheel.

Therefore, the greater the dimensions selected for the internal gear rim and the planet wheel, the greater too is the stroke to be executed by the reaping blade. As a result of the very wide cutting mechanisms customary today, with correspondingly long and heavy reaping blades, limits are set to the number of strokes owing to the associated vibrations of the reciprocating blades. By' increasing the stroke, combined with an increase in the number of cuts resulting from the fact that each blade passes over more than one counter-blade, the number of load alternations can be greatly reduced without any reduction in reaping performance. If, for example, the stroke is doubled, the number of strokes can be halved, and yet the cutting performance remains unchanged.

However, particularly when the intention is to execute a long stroke, the gears hitherto disclosed with a stationary internal gear rim and planet wheel are of very wide and high construction. On the one hand, the gear wheel must be fixed in a housing, necessitating a housing of appropriate size, and on the other hand the planet wheel is mounted in the rotor by means of a double mounting, as a result of which the rotor bearing must be of very large diameter, since the mounting of the planet wheel axle demands a correspondingly large rotor diameter. Such bearings are very expensive. The mounting of the planet wheel is also very expensive in the designs described, as are the connecting members between planet wheel and crank pin. The assembly and dismantling of this type of gear is also very complicated and iabour-intensive.

The object of the present invention, therefore, is to construct a gear in such a manner that on the one hand the dimensions selected can be very slender, and on the other hand a design can be produced which is much more economical and easier to assemble.

This object is achieved by means of a drive gear for reciprocating reaping blades of harvesting machines having a rotor rotating in a housing, a planet wheel being mounted on this rotor, rolling within a stationary internal gear rim and being connected to a crank, the diameter of the planet wheel coinciding with the radius of the internal gear rim and the radius of the planet wheel coinciding with the radius of the crank, the said gear being characterised in that the planet wheel is integrally designed as a crank or as a holder for a crank or a crank bearing.

As a result of this integral construction, it is possible to accommodate within the planet wheel itself at least one bearing of the two bearings naturally required for reasons of strength, and to mount this bearing on a connecting piece of the rotor. In this arrangement, the connecting piece can be set inside the rotor or alternatively integrally moulded onto the rotor.

The second bearing required can, as shown in Fig. 2, likewise be accommodated within the planet wheel. It has now been found that the second bearing can be retained with much greater stability if it is mounted on the neck of the planet wheel and within the rotor.

In a drive gear of this design according to the invention, all structural components are of relatively lightweight and space-saving design.

The gear is virtually maintenance-free, since all the bearings used are lubricated and sealed for its entire service life. Only the internal gear rim requires greasing.

According to another embodiment of the invention, the planet wheel is mounted on a connecting piece of the rotor, or alternatively the planet wheel is mounted in a hole in the rotor.

In order better to illustrate the difference between the gear according to the invention and the known state of the art, the known state of the art is described below with the aid of Fig. 1 of the drawing, and the gear accord ing to the invention is explained with the aid of further illustrative drawings. In order to clarify the proportions, the drawings illustrate approximately the natural size both of the known state of the art and of the gear accord ing to the invention.

In the drawings: Figure 1 shows the illustration of a gear according to the known state of the art in the form of a diagrammatic cut-away model; Figure 2 shows a gear embodiment accord ing to the invention in the form of a diagram matic cut-away model having a crank bearing attached to the toothed planet wheel; Figure 3 shows an illustration according to Fig. 2, seen from below; Figure 4 shows a planet wheel designed according to the invention having a crank pin integrally moulded thereon; Figure 5 shows an alternative version of the external shape of the gear housing, illustrated on a small scale; Figure 6 shows a further cut-away model with internal and external mounting of the planet wheel.

The gears of the type described initially which have hitherto been disclosed consist of the housing 1, in which the rotor 2 is rotatably mounted by means of the bearings 3 and 4. The rotor itself consists of two parts which are connected at the line 5 by means of screws 6. The crank 7 is mounted within the rotor by means of the bearings 8 and 9.

Fixedly connected to the crank 7 is the planet wheel 10, which rolls in the internal toothed wheel 11 when the rotor 2 is driven. As a result of the rolling, the crank 7 is set in contrary movement to the rotor, so that as a consequence of the geometrical conditions, the crank pin 12 executes an absolutely linear movement. In this type of gear, the bearing 3 has to have a very large internal diameter.

The greater the blade stroke required and the diameter of the crank shaft 7, the greater this diameter of the bearing 3 must be. In order to accommodate the bearing 9 with sufficient stability, which makes appropriate dimensions necessary, the rotor must be divided at the line 5, since the upper part of the rotor must then likewise have a corresponding diameter.

The internal gear rim 11 is then rigidly attached to the housing 1 between the upper part of the rotor and the lower part of the rotor, and for this reason alone requires that the rotor be divided in two.

A design has also been disclosed in which the bearing 9 is kept so small that it is possible to select a diameter for the upper part of the rotor which still just permits it to be pushed through the internal gear rim 11.

The associated very small shaft diameter of the crank 7 can no longer be used with the heavy reaping blades in use today and/or with a greater stroke of the reaping blade, since the stresses are too high.

Finally, German Offenlegungsschrift 2,031,864 illustrates a design in which the crank shaft is mounted in space-saving needle bearings. Nevertheless, however, this gear is still of very wide construction and expensive.

The greatest disadvantage of this gear, however, consists in the fact that the crank shaft is not firmly guided axially. The alternating load in the case of reciprocating reaping blades requires, however, as is found in practice, absolutely secure axial guiding of the crank shaft, since otherwise the radial bearings will be destroyed within a short time.

A further serious disadvantage is that, in the design described, the drive and the power take-off are situated too far apart. For this reason, in accordance with the lever principle, all intermediate structural members must be of correspondingly large dimensions.

Finally, the attachment of the planet wheel 10 to the axle 7 causes great difficulties.

Because of the alternating load imposed, a high-precision fit must be produced and the planet wheel must be precisely fixed relative to the gearing and crank pin.

The present invention eliminates these disadvantages.

In the case of a planet wheel integrally designed as a crank or as a holder for a crank or a crank bearing, all difficult connections and similarly all difficult assembly work are eliminated.

Exemplary embodiments of the invention are described in greater detail in Figs. 2 to 6.

In Fig. 2, the integral rotor 20 is mounted in the housing part 23 by means of the bearings 21 and 22. The connecting piece 24 is integrally formed from the rotor, but can also be screwed to, welded into or pressed into the actual rotor as a separate component.

In any case, connecting piece and rotor form a unit. The planet wheel 25 is mounted on the connecting piece 24 by means of the bearing 26 in such a way that it is also free of axial play. This is achieved in that the inner ring of the bearing 26 is firmly pressed against the shoulder 28 of the rotor by means of the collar screw 27. The outer ring of the bearing 26 is firmly tensioned in the geared planet wheel 25 by means of the ring nut 29.

The geared planet wheel 25 is integrally designed as a holder 38 for the bearing block 30, and thus similarly forms the crank necessary for operation. The internal gear rim 31 is fixedly connected to the housing part 23 and simultaneously forms the lower part of the housing. The planet wheel 25 rolls within the internal gear rim 31 in contrary motion to the direction of rotation of the rotor 20.

The reaping blade is directly and rigidly attached to the threaded sleeve 32. The sleeve 32 is mounted in the bearing block 30 by means of the bearing 33.

The integral design of the connecting piece 24 and the rotor 20, and the integral design of the geared wheel 25 as a crank, result in an exceptionally high static stability, permitting all bearings and structural components to be of very small dimensions. The rotational force of the rotating geared wheel 25 is, for example, transmitted direct to the housing 30, in other words not via a special crank shaft.

As a result, the bearing steess on the bearing 26 and the connecting piece 24 is likewise very slight. Since, in the exemplary embodiment, all bearings are permanently lubricated and sealed, no maintenance is necessary. Only the geared wheels require greasing.

To prevent this lubricant escaping, and also to prevent the entry of dust and dirt, a sealing washer 34 is attached to the rotor 20, and thus rotates with the latter. It has proved to be particularly advantageous if this sealing washer made from thin but toughly resilient sheet metal. The sealing washer can be divided in two at the centre, so that it can be laid about the neck of the planet wheel 25 and provide a dust-proof seal there. Small quantities of emerging grease are desirable, as these form a beaded rim and hence provide additional sealing against dust.

In the internal gear rim 31, the sealing washer can run in a groove 35, which can either be machined directly in the internal gear rim or be formed by an anular washer 36. In both cases the result is a type of labyrinth seal, which is perfectly adequate for this case of application.

The external basic form, square in section, of the housing with the internal gear rim 31 can be seen in Fig. 3. As mentioned, this form can also be rectangular or, as described below, provided with suitable surfaces to enable it to be screwed onto the machine in question. The holes 40 are provided for fixing the internal gear rim 31 to the upper part 23 of the housing, and the threaded holes 41 for attaching the gear to the machine.

Also visible in Fig. 3 are the packing washer 34, divided in two at 42 and attached to the rotor 20 by means of the screws 43, the annular washer 36, attached to the internal gear rim 31 by means of the screws 44, and the retaining part 38 of the geared planet wheel 25 to which the crank bearing 30 is attached by means of the screws 45.

Fig. 4 shows an alternative way of attaching the reaping blades. The planet wheel 25 possesses, as an integral part, the crank pin 50, on which a bearing block 51 is mounted via the bearing 52. The reaping blade is attached to this bearing block in a conventional manner. Instead of being designed integrally with the planet wheel, the pin 50 can also, like the crank bearing 30 in the exemplary embodiment described above, be attached in the same manner and by a similar fit to the retaining part 38 of the planet wheel 25.

Finally, Fig. 5 shows an alternative outer shape of the housing with the internal gear rim 31, two surfaces 60 and 61 being provided on an oval or round basic shape of the gear housing for the internal gear rim, and serving to attach the gear to the machine concerned.

Fig. 6 shows an alternative embodiment of the gear according to Fig. 2. The planet wheel 70 is mounted 'by means of an internal bearing 71 on the connecting piece 72 of the rotor 73 and by means of an external bearing 74 in a bearing hole in the rotor 73. As a result a very stable mounting is produced, combined with very simple assembly. The planet wheel with both bearings is introduced from below and them only needs to be secured and fixed in the bearing hole by means of the securing ring 75. In this embodiment the connecting piece 76 of the planet wheel can be designed not only integrally as a crank but also as a holder for a crank or a crank bearing. There are thus numerous possible designs according to the invention. The embodiments according to Figs. 2, 3, 4 and 6 are thus merely to be regarded as preferred exemplary embodiments.

Claims

1. Drive gear for reciprocating reaping blades of harvesting machines having a rotor rotating in a housing, a geared planet wheel being mounted on this rotor, rolling within a stationary internal gear rim and being connected to a crank, the diameter of the planet wheel coinciding with the radius of the internal gear rim and the radius of the planet wheel coinciding with the radius of the crank, characterised in that the planet wheel (25), (70) is integrally designed as a crank or as a holder for a crank or a crank bearing.

2. Drive gear according to Claim 1, characterised in that the planet wheel (25), (70) is mounted on a connecting piece (24) of the rotor (20), (73).

3. Drive gear according to Claim 1, characterised in that the planet wheel (25), (70) is mounted in a hole in the rotor.

4. Drive gear according to Claim 1, characterised in that the planet wheel (70) is mounted by means of an internal bearing (71) on a connecting piece (72) and by means of an external bearing (74) in a hole in the rotor (73).

5. Drive gear substancially as described with reference to and as illustrated in any one or more of Figs. 2 to 6 of the accompanying drawings.