WO2007135705A1

WO2007135705A1 - Irreversible gearing, in particular for gearmotors for operating roller shutters and/or awnings

Info

Publication number: WO2007135705A1
Application number: PCT/IT2007/000359
Authority: WO
Inventors: Massimiliano Rovinelli
Original assignee: Rovinelli Bruno S.R.L.
Priority date: 2006-05-24
Filing date: 2007-05-22
Publication date: 2007-11-29
Also published as: ITAN20060035A1

Abstract

An irreversible reducer gearing, comprising a driven shaft (2), a driving shaft (6) and gear trains (22), wherein a first gear (23) is associated with the driving shaft (6) and a second gear (3) meshes with the first gear (23); also comprising a casing (1) housing a ring gear (11). The driven shaft (2) comprises a main journal (25), supported by the casing (1), a crank pin (7), parallel with the main journal (25) and a crank arm (26), transversal to the main journal and crank pin (25, 7). The second gear (3) is supported by the crank pin (7). The gearing (10) has a third gear (4) which meshes with the ring gear (11) and has a bearing cavity (19); it also has a first crank (27) in turn comprising its own first pin (20) which can be associated with a corresponding third gear (4) bearing cavity (19).

Description

Irreversible gearing, in particular for gearmotors for operating roller shutters and/or awnings

Technical Field

The present invention relates to an irreversible speed gearing, that is to say, with no backward motion.

The gearing may advantageously be applied in tubular gearmotors for driving roller shutters and awnings. These are applications referred to below, by way of example only and without in any way limiting the scope of the invention, since the gearing may also advantageously be used both for manual operation, not necessarily motor-driven, and for general uses which may also relate to application environments completely different to that referred to.

Background Art

For automating the downstroke and return upstroke of roller shutters designed to cover windows, inside or outside the window unit, for driving continuous arm curtains, for bringing out and retracting security grilles for doors and windows, use is known of gearmotors with a tubular, cylindrical casing, which basically comprise four characteristic and fundamental assemblies of component elements: an electric motor; a speed gearing, of which a driving shaft and a driven shaft are an integral part; a braking apparatus; and an end of stroke apparatus for the user element, for example the roller shutter or the awning. The driving shaft is integral with the electric motor, with which it rotates integrally at a predetermined speed.

The driven shaft is integral with the user element, movable, and rotates at a speed which is lower than the speed of the driving shaft and specific for the application involved on each occasion.

Gearings made in this way must have very low gear ratios (the gear ratio here being the ratio between the number of revolutions of the driven shaft and the number of revolutions of the driving shaft, respectively described in the unit of time). Consequently, in applications of such a type, the use of epicyclic reduction gears is widespread.

The braking apparatus is designed to prevent backward motion of the movable element, for example the downstroke of the roller shutter with the motor stopped, or even movement of the roller shutter forced by a manual action applied to the roller shutter.

In general, such a braking apparatus is present in most known gearmotors (such a solution is described for example in document EP0976909).

In some applications the braking apparatus is physically separate from the gearing; in others it is integrated in the gearing, being associated with some of the gears.

There are also multi-stage epicyclic reduction gears, with two or more gear trains, in which the braking apparatus may be completely absent, since the gearing is in itself irreversible (such a type of gearing is described for example in document EP 1013872). The end of stroke apparatus has the obvious purpose of automatically defining the end limits of the range of movement of the element controlled.

With regard to the production of the gearings described above, the prior art has many disadvantages.

Firstly, in terms of construction the prior art reducer gearings are quite complex and expensive. The braking apparatus contributes significantly to said complexity and expense.

It should be noticed that the braking apparatus, when present, not only contributes to the complexity of the construction of the entire assembly and therefore has a negative effect on construction costs, but also involves the need for various calibration conditions, related to the different types of electric power used in different countries. Moreover, the presence of a braking apparatus also entails the need for systematic maintenance work for the entire life of the gearing.

The situation does not improve in gearmotors with multi-stage irreversible gearings. Although they do not have the braking apparatus, the increased construction complexity of the gearing is such that it largely wipes out the benefits of the absence of the braking apparatus.

Disclosure of the Invention

The aim of the present invention is to overcome the above-mentioned disadvantages. Accordingly, the invention achieves this aim with an intrinsically irreversible gearing, having a new and original design compared with the classic type of epicyclic reduction gears with or without braking apparatus.

The technical features of the present invention are clear from the content of the claims herein, in particular claim 1, and from any of the claims directly or indirectly dependent on claim 1.

Brief Description of the Drawings

The advantages of the present invention are more apparent in the detailed description which follows, with reference to the accompanying drawings which illustrate preferred, non-limiting embodiments of the invention, in which:

Figure 1 is an exploded perspective assembly view of a gearing in accordance with the invention;

Figure 2 is a side view of the gearing of Figure 1, in a tightly assembled configuration and seen from the motor side; Figure 3 is an axial section of the gearing of Figure 2;

Figure 4 is a schematic view of the geometry of a detail of the invention.

Detailed description of the Preferred Embodiments of the Invention

With reference to the accompanying drawings, the numeral 10 denotes as a whole an irreversible speed reducer gearing, preferably but not exclusively for means for operating roller shutters and/or awnings comprising for example a generic tubular gearmotor for motor-driven operation.

The gearing 10 substantially comprises a hollow tubular cylindrical casing 1, housing a ring gear 11 with straight teeth. Said ring gear 11 preferably consists of 60 teeth.

The casing 1 supports a driving shaft 6 and a driven shaft 2, designed to be associated, respectively: the former with an electric motor not illustrated; the latter with a generic user element, for example a winding drum of a roller shutter or an awning, also not illustrated, since they are not relevant to the invention described. The driven shaft 2 substantially comprises a main journal 25, supported by the casing 1 by relative rolling or sliding bearings 5; three crank pins 7, parallel with one another and with the main journal 25; and a crank arm 26, preferably disk-shaped and angled transversally to the main journal 25 and to the crank pins 7.

The casing I₅ the driving shaft 6 and the main journal 25 of the driven shaft 2 all share the same axis of rotation 15, along which the driving shaft 6 and the main journal 25 of the driven shaft 2 are consecutive and about which the casing 1 can rotate.

The driving shaft 6 is straight and has end portions, the first of which is labelled 12, the second labelled 13. The first end portion 12 of the driving shaft 6 is rigidly connected, directly or indirectly, with the electric motor. For this reason there is an engagement cavity 31, for engaging and driving the rotation of the driving shaft 6.

The second end portion 13 of the driving shaft 6 has a first gear 23, made in the shaft 6 itself and having external toothing 14 preferably with 9 teeth. The casing 1 houses three gear trains 22, each combining its own second gear

3 with the first and only gear 23 on the driving shaft 6. hi other words, the gear trains 22, as defined above, overall comprise a single sun gear, represented by the first gear 23 of the driving shaft 6, and three second planet gears 23 which mesh with the outside of the first gear 23. The three second planet gears 3: are identical; having external toothing 16 which preferably comprises 18 teeth; and are angled with their axes of rotation 17 parallel with the axis of the driving shaft 6. Moreover, they are positioned around the end portion 13 of the driving shaft 6 in such a way that they are separated by equal angles. The three second planet gears 3 are supported with freely rotating connections by three corresponding crank pins 7 of the driven shaft 2. Said pins 7 project cantilever style from the disk-shaped crank arm 26, axially passing through the three second gears 3 and project towards the driving shaft 6, until they collectively abut with their distal end 30 on a supporting element 8. The supporting element consists of a three-sided plate, mounted on the driving shaft 6 annularly and axially.

The crank pins 7, due to the connection of their ends: on one side to the crank arm 26; and on the other side to the supporting element 8, have a high bending strength which guarantees that the gearing 10 functions correctly and in a lasting manner even in the presence of intense loads exchanged between the driving shaft 6 and the driven shaft 2.

It should also be noticed that the axial-symmetrical shape in particular of: the crank arm 26; the supporting element 8; and the position of the three crank pins 7 with the relative three second gears 3; and finally the tubular shape of the casing 1; allow a balanced distribution of masses which allows the gearing 10 to function with reduced vibrations.

Figure 3 and, even more clearly Figure 4, show how the second planet gears 3 have a first crank 27 directly associated with a corresponding crank pin 7 of the driven shaft 2. This first crank 27 consists of a first eccentric cylindrical pin 20, made on the second gear 3. Said first pin 20 has an annular cylindrical shape which allows freely rotating axial connection with the crank pin 7.

The annular cylindrical shape is delimited by an internal surface 29 which is concentric with the corresponding matching and coupled surface of the crank pin 7; but at the same time it is also delimitated by an external surface 28 which, vice versa, is eccentric relative to the crank pin 7, that is to say, relative to its geometric axis 17.

Each of the second gears 3 also has, in a single body with its toothing 16, a second pin 21 consecutive relative to the first pin 20. Said second pin 21 is identical to the first, however, the angle of its eccentricity is different, as described in more detail below.

As Figure 4 clearly shows, the first pin 20 closest to the toothing 16 has suitable eccentricity relative to the axis 17 of the crank pin for rotation of the second planet gear 3; the second pin 21, furthest from the toothing 16, has the same eccentricity as the first pin 20, but the direction radial to the axis 17 according to which said eccentricity manifests it maximum value is offset at an angle about the axis 17, relative to that of the first pin 20.

Between the driving shaft 6 and the driven shaft 2, the casing 1 housing a pair of third gears 4, identical and having external toothing 18 preferably with 59 teeth.

The third gears 4 have cylindrical bearing cavities 19, in particular six bearing cavities 19, centred and distributed regularly along a circle.

Three alternate bearing cavities 19 of one of the third gears 4 (that is to say of the third gear 4 closest to the driving shaft 6) connect in a turning fashion with the first pins 20 of the second planet gears 3, whilst the external toothing 18 of the third gear 4 simultaneously meshes with the casing 1 internal ring gear 11. The same applies for three alternative bearing cavities 19 of the second of the third gears 4 which, vice versa, is furthest from the driving gear 6. These latter bearing cavities 19 connect in a turning fashion with the second eccentric pins 21 of the second planet gears 3, whilst the external toothing 18 of the furthest third gear 4 meshes with the casing 1 internal ring gear 11, but in a position offset at an angle to the position of meshing of the third gear 4 closest to the toothing 16 of the second planet gears 3.

It should be noticed that, as for the first pin 20, again in the case of the second pin 21, the eccentricity (radius of the first crank 27) corresponds to the centre-to- centre of operation of the pair of gears consisting of the combination of each of the third gears 4 with the casing 1 ring gear 11. Operation of the gearing 10 may be described by observing that the rotation of the driving shaft 6 drives the rotation of the second planet gears 3 about the axis 17 of the crank pins 7 with a speed of rotation that depends on the speed of the driving shaft 6 and the meshing ratio between the toothings 16 and 14 of the second planet gear 3 and the first gear 23 on the driving shaft 6.

During their rotation, the second planet gears 3, due to the eccentricity of their pins 20 and 21, move the point of contact (centre of instantaneous rotation) of the third gears 4 with the casing 1 ring gear 11. A complete revolution by the second planet gears 3 about the axis 17 of the crank pins 7 corresponds to a complete 360° revolution by the point of contact between the toothing 18 of each third gear 4 and the casing 1 ring gear 11.

In other words, a complete revolution of the second planet gear 3 corresponds to a complete revolution of the third gear 4, but since the latter has one less tooth than the casing 1, there is a phase difference equal to:

_ teeth _ ca sin g - teeth _ sec ondgear teeth - sec ondgear which, with reference to the numbers of teeth used in the example described gives a phase difference value of

a = 360° * ^{6Q ~ 59} = 6,102° The phase difference a is also transferred by the crank pins 7 to the driven shaft 2, which is rotated through said angle.

Finally, since the rotation of the second planet gears 3 is in turn driven by the driving shaft 6, the total gear ratio between the driving shaft 6 and the driven shaft 2 will be the product of the two partial gear ratios. Therefore, in the case in question, in which the driving shaft 6 has 9 teeth and the second planet gears 3 have 18 teeth, the ratio will be

2*59 = 118:1 meaning that one revolution of the driving shaft 6 corresponds to 1/118 of a revolution of the driven shaft 2. As regards the type of toothing to be used, experiments have shown that cycloidal toothing allows improved gearing 10 irreversibility. In contrast, the use of involute toothing allows greater direct motion.

It should also be noticed that the use of two third gears 4 does not affect gearing 10 kinematic operation. However, the presence of two or more third gears 4 has the advantage of balancing the gearing 10 with the effect of significantly reducing its vibrations, specific stresses and operating noise.

Therefore, the invention described has many advantages over the prior art, which may be summarised as follows.

The costs of construction and maintenance of the gearing 10 disclosed are significantly less than the costs of prior art reducers, due to the complete absence of physical elements which perform friction braking actions.

The complete absence of a braking apparatus eliminates all problems linked to brake calibration and helps to make the gearing 10 more reliable.

The irreversibility of the motion is guaranteed for any external, inverse load condition. This feature - which guarantees the immobility of the user element when it is forced by manual operation and which is particularly significant for safety purposes to prevent tampering - is not found in reducers equipped with a separate friction braking device, and, although it can be obtained in multi-stage epicyclic reduction gears without a braking device already known, compared with the latter it is obtainable with the advantage of a more simple construction, lower costs and a more compact structure.

The gearing 10 disclosed, if compared with conventional epicyclic gearing having an identical gear ratio, demonstrates that it has approximately half the components of the latter, with evident and consequent advantages in terms of the costs of production, storage and logistics.

Compared with an epicyclic gearing of the same size, the gearing 10 has a larger number of teeth simultaneously meshing, which translates into a greater capacity for absorbing impacts without damage.

Moreover, as is completely confirmed by experimental evidence, the gearing 10 disclosed is quieter than normal, average-quality epicyclic gearing. This result is particularly significant for domestic and/or home applications in general.

The invention described above is susceptible of industrial application and may be modified and adapted in several ways without thereby departing from the scope of the inventive concept. Moreover, all details of the invention may be substituted by technically equivalent elements.

Claims

1. An irreversible reducer gearing, comprising a driven shaft (2); a driving shaft (6); at least one gear train (22), wherein a first gear (23) is associated with the driving shaft (6) and at least one second gear (3) meshes with the first gear (23); and a casing (1) housing a ring gear (11); the gearing (10) being characterised in that

- the driven shaft (2) comprises a main journal (25), supported by the casing (1), at least one crank pin (7), parallel with the main journal (25) and at least one crank arm (26), transversal to the main journal and crank pins (25, 7);

- the one or each second gear (3) being supported by a corresponding crank pin (7) belonging to the driven shaft (2); the gearing also being characterised in that it comprises

- at least one third gear (4) which meshes with the casing (1) ring gear (11) and has at least one bearing cavity (19); and

- at least one first crank (27) associated with a corresponding crank pin (7) belonging to the driven shaft (2) and in turn comprising its own first pin (20) which can be associated with a corresponding third gear (4) bearing cavity (19).

2. The gearing according to claim 1, characterised in that the driven shaft (2) has a single, disk-shaped crank arm (26).

3. The gearing according to claim 1 or 2, characterised in that the casing (1) has a tubular cylindrical shape.

4. The gearing according to any of the foregoing claims, characterised in that the main journal (25) of the driven shaft (2), the driving shaft (6) and the casing

(1) are coaxial with one another.

5. The gearing according to claim I₅ characterised in that the first pin (20) of the first crank (27) has an annular cylindrical shape and an external surface (28) which is eccentric relative to an axis (17) which is the geometric axis of the driven shaft (2) crank pin (7).

6. The gearing according to claim 5, characterised in that the first pin (20) of the first crank (27) has an internal surface (29) concentric with the corresponding driven shaft (2) crank pin (7).

7. The gearing according to claims 5 and 6, characterised in that the first pin (20) is monolithic with a corresponding second gear (3).

8. The gearing according to any of the foregoing claims, characterised in that the third gear (4) has a number of teeth equal to the number of teeth of the ring gear (11) minus one.

9. The gearing according to claim 5, characterised in that the external surface (28) has an eccentricity value corresponding to an operating centre-to-centre of a pair of gears comprising the third gear (4) and the casing (1) ring gear (11).

10. The gearing according to any of the foregoing claims, characterised in that it comprises a plurality of driven shaft (2) crank pins (7), the number of crank pins (7) present corresponding to the number of second gears (3).

11. The gearing according to claims 2 and 10, characterised in that the driven shaft (2) crank pins (7) are associated with a single driven shaft (2) crank arm (26).

12. The gearing according to claim 10 or 11, characterised in that there are three driven shaft (2) crank pins (7).

13. The gearing according to any of the foregoing claims, characterised in that it comprises three second gears (3), all identical, positioned around the driving shaft (6) in such a way that they are separated by equal angles.

14. The gearing according to claim 8, characterised in that the third gear (4) has a plurality of bearing cavities (19), the number of cavities (19) at least corresponding to the number of driven shaft (2) crank pins (7).

15. The gearing according to any of the foregoing claims, characterised in that it comprises at least one supporting element (8) for supporting the one or each corresponding driven shaft (2) crank pin (7) at one end (30), furthest from the driven shaft (2).

16. The gearing according to claim 15, characterised in that the supporting element (8) has the shape of a plate, supported by the driving shaft (6).

17. The gearing according to any of the foregoing claims, characterised in that the second gear (3) has twice the number of teeth of the first gear (23).

18. The gearing according to claim 1 or 8, characterised in that it comprises at least two identical third gears (4), parallel with one another and respectively meshing with the ring gear (11) at points of the ring gear (11) such that the circumference of the ring gear (11) is divided into substantially equal parts.

19. The gearing according to claims 1 and 18, characterised in that one or each first crank (27) associated with the driven shaft (2) crank pin (7) has its second pin (21) consecutive with the first pin (20), there being the possibility of associating the second pin (21) with a corresponding bearing cavity (19) in the second of the third gears (4).

20. The gearing according to claim 19, characterised in that the second pin (21) and the first pin (20) of said one or each first crank (27) are monolithic with one another and integral with a corresponding second gear (3).

21. The gearing according to any of the foregoing claims, characterised in that the gears (23, 3, 4, 11) have teeth with an epicyclic profile.

22. The gearing according to any of the foregoing claims from 1 to 20, characterised in that the gears (23, 3, 4, 11) have teeth with an involute profile.

23. The gearing according to any of the foregoing claims, characterised in that it is applied to means for operating roller shutters or awnings.

24. The gearing according to claim 23, characterised in that the operating means include gearmotors for motor-driven operation of the roller shutters or awnings.