DESCRIPTION

The present invention relates to a geared transmission of the type including a case and at least a first reduction stage with orthogonal axes and a second reduction stage with parallel axes.

In the relevant technical field, there are known geared speed reducers which comprise a case or casing which houses a reduction stage with orthogonal axes and one or two reduction stages with parallel axes. For example, French patent FR 2211085 describes a speed reducer which receives motion from an electric motor and transmits it to a first reduction stage with parallel axes. The output shaft of the first reduction stage is connected to a second stage with orthogonal axes, formed by a bevel pinion and a corresponding crown wheel.

This patent describes two different embodiments which can be used, according to the transmission ratio required by the specific application. In a first embodiment, the motion output shaft is connected directly to the crown wheel of the second reduction stage, while in the second embodiment there is a further reduction stage with parallel axes, positioned at the output of the second stage.

Although the two solutions have many components in common, each version requires a specific design of the casing and the shaft supports, thus greatly reducing the versatility of this type of speed reducer.

In particular, given that the casing is typically the most costly component of a speed reducer, this lack of versatility, particularly in speed reducers intended for general rather than specific use, is reflected, above all, in the cost of the device, since every different version requires a redesign of this component and of the corresponding structure of the speed reducer.

Further speed reducers are described in the patent US 2,622,453 and in the utility model CN 202 158 140.

However these speed reducers are, beyond not sufficiently versatile, even complex in the assembling phase, not being the inner volume of the casing easily accessible.

The technical problem to be solved by the present invention is therefore that of providing a speed reducer structurally and functionally designed in such a way that all the aforementioned drawbacks of the prior art can be overcome.

This problem is resolved by means of a geared transmission according to Claim 1.

Preferred characteristics of the invention are defined in the dependent claims.

The present invention enables speed reducers to be produced with different operating configurations, using a large number of common elements, particularly the same housing case, thereby increasing versatility and reducing production costs.

Furthermore, the gears assembly can be performed in an effortless manner, being guaranteed an optimal accessibility to the inner part of the transmission.

The characteristics and further advantages of the invention will be more clearly apparent from the following detailed description of a preferred, but non-exclusive, example of embodiment of the invention, illustrated, for guidance and in a non-limiting way, with reference to the attached drawings, in which :

- Figure 1 is a sectional plan view of a geared transmission according to the present invention;

- Figure 2 is a side view taken through the section A-A of the geared transmission of Figure 1;

- Figures 3A to 3D are, respectively, a sectional plan view and side and front views taken through the sections B-B, C-C and D- D of a housing case forming a detail of the geared transmission according to the present invention;

- Figure 4 is a partial plan view, in detail, of the geared transmission of the present invention, according to an alternative embodiment;

- Figure 5 is a sectional plan view showing different possibilities of configuration of the geared transmission according to the present invention; and

- Figure 6 is a sectional plan view of the geared transmission of the present invention, according to a further alternative embodiment.

With initial reference to Figure 1, a transmission according to the present invention is indicated as a whole by the reference numeral 100.

The transmission 100 comprises a housing case 10, which, in the present embodiment, houses a first reduction stage 1 with parallel axes which, in the present embodiment, comprises a motion input shaft 110, receiving its motion from a motor, for example an electric motor; a reduction stage 2 with orthogonal axes; and a third reduction stage 3 with parallel axes. It should be noted that, more generally, the transmission 100 according to the present invention comprises at least one reduction stage with orthogonal axes and a reduction stage with parallel axes, and is additionally usable, as will be demonstrated subsequently with reference to alternative embodiments, for solutions with two reduction stages.

According to a preferred embodiment, the housing case 10 has a parallelepipedal shape. Therefore six faces are defined in the housing case, as indicated in the drawing by reference numerals 11 to 16, each face being orthogonal to the adjacent faces.

More generally, different shapes may be provided for the case 10, provided that at least five faces are defined, each substantially orthogonal to those adjacent to it.

In each of the aforesaid five faces there is at least one opening, the openings being represented in the figures by the reference numerals 11a, 12a, 12b, 13a, 13b, 14a, 15a and 15b.

Each of the aforesaid openings is intended for the passage and/or the support of a corresponding shaft of the reduction stages described above, according to procedures described below.

Additionally, at least one enlarged opening, which in the present case is the opening 14a, has dimensions such as to allow the passage and partial housing of the gears used in the transmission according to the present invention.

In this way, it is possible to assemble the transmission where the case is made as a single body, that is to say formed by a single casting. According to the present embodiment, the first reduction stage comprises a pair of cylindrical gears 11 and 12, keyed, respectively, on the input shaft 110 and on a driven shaft 120.

The driven shaft 120 forms the driving shaft of stage 2 with orthogonal axes, and for this purpose it supports a bevel pinion 21 of the second reduction stage 2. The bevel pinion 21 engages with a corresponding crown wheel 22 keyed on a driven shaft 230 of the second reduction stage 2, orthogonal to the shaft 120.

In its turn, the driven shaft 230 of the second reduction stage 2 forms the driven shaft of the third reduction stage, and for this purpose comprises a further gear 31 which engages with a gear 32 keyed on an output shaft 320, which thus transmits the motion of the motor with a speed reducing transmission ratio.

As mentioned above, the gears and shafts used in the transmission according to the present invention can be inserted through the openings which are formed, and in particular through the enlarged opening 14a, which has dimensions sufficient and appropriate for the purpose, which, in the present embodiment, are greater than the other dimensions.

As can also be seen in Figures 3A to 3D, the openings, except for the enlarged one, are preferably circular in shape and are of a size suitable for housing the outer race of a corresponding rotary bearing which supports, preferably by means of a removable supporting plate 41, described in more details in the following, an end of one of the aforementioned shafts. According to a preferred embodiment, the transmission further comprises a pair of supports 4 intended for fixing a further rotary bearing which supports an end of the driving shaft 120 of the second reduction stage 2.

Preferably, the supports extend within the housing case 10 from opposite faces 13, 15 thereof and are made as a single body with the housing case 10 itself.

Moreover, the supports 4 are extending from the respective faces in direction substantially perpendicular, towards the inner part of the housing case 10.

Additionally, the supports 4 are positioned so that they are placed facing the enlarged opening 14. Additionally, a sufficient space is provided between the supports 4 to allow the housing or the passage of the bevel pinion 21 and of the bull gear 31.

Position and dimensions of supports 4 are such not to interfere with the bevel wheel 22 as the assembly of the supporting plate 41 is achieved.

The supports 4 can advantageously be used to fix, preferably by means of bolts and/or pins, not shown in the figure, a support plate 41 on which is housed the rotary bearing supporting an end of the driving shaft 120 of the second reduction stage 2.

At the same time, the position of supports 4 corresponding to the enlarged opening 14a allows to easily insert all the gears to be used in the transmission, without renouncing to use a housing case 10 made as a single body.

This solution has the advantage of allowing easy adjustment of the axial position of the pinion 21 by means of shims, not shown in the figure, to be inserted between the supports 4 and the plate 41, thereby discharging the considerable forces acting on the bearing directly on to the structure of the case 10 itself.

In order to provide a closure for the opening 14a, the transmission according to the present invention further comprises a closing cover 140 that can be fixed to the case 10 at the position of the opening 14a.

Additionally, according to a preferred embodiment, the supporting plate 41 is fixed or fixable to the support 4 in a removable manner. In order to allow an easy assembly and adjustment of the pinion 21 of the bevel couple by means of shims, the removable supporting plate 41 must be easily mountable and unmountable jointly with pinion 21 and corresponding pre-assembled rotary bearings. Preferably, the locking of the supporting plate 41 to support 4 is achieved by reversible fixing means 5, shown in figure 9, for example produced by bolts or pins.

For this reason it is necessary that the plate 21 has such dimensions to allow the passage without particular operations through the opening 14a while the wheel 112 and corresponding rotary bearings on the pinion 21are still mounted.

Moreover, for this aim the fixing means 5 are preferably positioned in an anyhow accessible way once the closing cover 140 is taken off.

For this the systems must preferably be placed in the space at disposal and accessible from the front between the wheel 112 and the opening 14a walls as shown in figure 9.

In the present embodiment, fixing means 5 are therefore placed in a zone of the supporting plate 41 comprised between the projection along the axes defined between the shaft 120 of the wheel 112 on the supporting plate 41 and the projection along the said axes of the enlarged opening 14a always on the supporting plate 41.

Additionally, according to a preferred embodiment, the closing cover comprises, in turn, openings 140a and 140b for supporting the input shafts 110 and the shaft 120.

Thus, advantageously, the case 10 can be simultaneously closed on completion of the assembly of the transmission, by positioning the corresponding bearings in the openings 140a and 140b.

With further reference to figures 1 and 2, according to a preferred embodiment, the openings 11a, 12a, 12b, 13a, 13b, 14a, 15a and 15b have centres which lie on the same midline plane of the housing case 10. This characteristic enables the transmission to be assembled in its various configurations without losing the alignment of the axes with other transmissions or other machines associated with the transmission. It should also be noted that, in the present embodiment, the midline planes are planes of symmetry, since the side faces of the case 10 are essentially mirror images of one another and are symmetrical . Again according to a preferred embodiment, the present invention refers also to transmission comprising the housing case, the reduction stage with orthogonal axes 2, the reduction stage with parallel axes 3, wherein the housing case 10 is made as a single body and comprises at least five faces, each one of them has at least a through opening and wherein the centres of the openings lie on the same midline plane, preferably corresponding to the symmetric plane, of the housing case 10.

Again according to a preferred embodiment, in order to optimize the overall dimensions, the transmission according to the present invention is made in such a way that the input axis 110 is interposed between the axes 230 and 320 of the third reduction stage 3.

Additionally, preferably, the crown wheel 22 and the bull gear 32 of the third stage 3 lie on opposite sides of the axis 110, as can be seen in Figure 2, which also helps to reduce the overall dimensions.

The symmetry of openings 13a, 13b, 15a, 15b allow in such a way to invert the position of the crown wheel 22 and the bull gear 32, thus inverting the rotation direction.

According to a preferred embodiment, at least three openings 11a, 12a, 14a are formed on respective faces 11, 12, 14 of the case 10, perpendicularly to the driven shaft 230 of the second reduction stage 2, that is to say the shaft supporting the crown wheel 22.

Thus it is possible to obtain different configurations of the transmission, such as that illustrated in Figure 6, which is described in greater detail below, and also, as shown in Figure 5, to provide further outputs and branches of the motion of the transmission.

This is because, owing to the presence of the aforesaid openings, the crown wheel 22 can engage not only with the pinion 21 of the second reduction stage 2, but also with further pinions 21' and 21", associated with respective output or branch shafts 120', 120" which can pass through the openings 11a and 12a.

At the same time, as mentioned above, these openings can also be used to provide different configurations of the transmission according to the present invention. By way of example, Figure 6 shows an alternative embodiment in which there are only two reduction stages, one with orthogonal axes and one with parallel axes.

In this case, the input shaft 110 is directly connected to the pinion 21 of the reduction stage with orthogonal axes 2, which in turn is connected to the reduction stage with parallel axes 3, as in the previous embodiment.

In this case, the housing case 10 uses a closing cover 140" having no openings, since it is not required to support shafts.

A further variant embodiment is illustrated in Figure 4, in which the supports 4 are not present, but, on the contrary, the shaft 120 is supported at both ends by a closing cover 140' having a support extension 141, preferably integral with the cover, in which a further opening 140c is formed for housing a bearing.

Thus, accordingly to this further embodiment, the present invention can be addressed to a transmission comprising the characteristics previously mentioned, except for support 4, wherein the closing cover comprises a support extension 141 having an opening 140c defining an outer rally for a rotary bearing for a 120 of the shafts 110, 120, 230, 320.

In this embodiment, the support 4 could however be present in the case 10 although not used.

Further variant embodiments of the present invention are illustrated in Figures 7 and 8. In the exemplary embodiment of Figure 7, a cover 140"', in which a volume 141 facing the inside of the case 10 is formed, is placed at the enlarged opening 14a. Thus the cover 140" can be used not only to close the opening, but also to share the lubricant of the case 10 by a free exchange process, thus helping to dissipate any heat generated during the operation of the transmission. Preferably, for this purpose, the cover 140"' has a plurality of external fins 142, for increasing the heat exchange surface, thereby improving the dissipation of the heat produced.

In the embodiment of Figure 8, on the other hand, the opening 14a is closed by a cover 140 ^IV , with similar characteristics to those defined for the preceding exemplary embodiment, which further comprises a heating device 143 for heating the gears inside the case 10, or via the common lubricant.

Thus the invention resolves the problem which was proposed, while providing a number of advantages. In particular, since the case is typically the most costly element of the transmission, the possibility of using a single casting yields considerable advantages in terms of cost and logistics, especially when the individual transmission configurations are not produced in large volumes.

Thus, by using a series of common components, including, in particular, the case, it is possible to provide various transmission configurations, and not only those described herein by way of non- limiting example, by providing the mechanism with further motion input and output options as necessary, which can be combined in various ways.

Thus it is possible to provide a transmission with a plurality of arrangements, including one generally used for connection to the motor by means of suitable coupling arrangements, the others normally being used to form power take-offs for moving further speed reducers in series, or other members of machines, or for receiving accessories such as brakes, auxiliary drives or lubrication pumps, which may also be combined with one another.

Additionally, the transmission according to the present invention can also be used for producing conventional speed reducers or geared motors without any particular cost increase compared with the currently available solutions.