Multistage angular reducer

Abstract: A multistage angular reducer (1) of the type having: a casing (2); a drive shaft (35); a driven shaft (11) connected to a user element; and a number of reduction stages (3, 4, 28) housed inside the casing (2), between the drive shaft (35) and the driven shaft (11), and wherein at least one stage (4) is defined by a pair of gears defined by a bevel pinion (9) and by a bevel ring gear (10); characterized in that the casing (2) may selectively house two (3, 4) or three (3, 4, 28) reduction stages, while maintaining unchanged, when switching from two (3, 4) to three (3, 4, 28) stages or vice versa, the mutual positions of the axis (K) of the drive shaft (35) and the axis (L) of the driven shaft (11).

Description: The present invention relates to a multistage angular reducer, which, by means of straightforward alterations and using the same casing, provides for switching from a two- to a three-stage design or vice versa. Such a reducer is described in US-A-3 214 989 (Wellauer et al.). Indeed, US-A-3 214 989 shows an angular reducer according to the preamble of claim 1 including a drive shaft, a driven shaft and a casing housing a number of reduction stages wherein one of the stages is defined by a bevel pinion and a bevel ring gear. Furthermore, the casing alternately houses two reduction stages or three reduction stages, wherein the mutual positions of the axis of the drive shaft and the axis of the driven shaft are maintained unchanged when switching between two reduction stages and three reduction stages. However, in US-A-3 214 989 two different casings are provided. The first one is able to receive three stages of reduction and is composed by several parts, whereas the second one is suitable for receiving a two-stage reducer. Thus, in US-A-3 214 989 it is necessary to fit the casing to the user's requirements, whereas in the present invention a single casing it is sufficient to house a two-stage or a three-stage angular reducer. It is an object of the present invention to provide a multistage angular reducer designed to overcome the aforementioned drawbacks. According to the present invention, there is provided a multistage angular reducer of the type according to claim 1. Moreover, the casing of the angular reducer according to the present invention also comprising a first inner supporting element and a second inner supporting element for respectively supporting the two ends of the drive shaft to which the pinion is fitted. In the case of a two-stage reducer, the bevel pinion is a hypoid bevel pinion. A number of preferred, non-limiting embodiments of the present invention will be described by way of example with reference to the accompanying drawings, in which (elements performing the same or similar functions are indicated using the same numbering system): Figure 1 shows a preferred embodiment of a two-stage angular reducer in accordance with the present invention; Figure 2 shows the first reduction stage of the reducer according to the present invention; Figure 3 shows a preferred embodiment of a three-stage angular reducer in accordance with the present invention and featuring the same casing as the Figure 1 reducer; Figure 4 shows a first side view of the casing of the reducer in Figures 1 and 3; Figure 5 shows a section of the first side view of the casing in Figure 4. In the Figure 1 embodiment, the angular reducer 1 comprises two reduction stages 3, 4 housed inside a casing 2. The first stage 3 is defined by a pinion 34 (of axis K - Figure 2) fitted to a shaft 35 and meshing with a second cylindrical gear 5 fitted to a shaft 6 supported by two bearings 7, 8. The second stage 4 in the Figure 1 embodiment is defined by a hypoid bevel pinion 9 meshing with a ring gear 10 integral with a driven shaft 11 (of axis L). As shown in Figure 1, hypoid pinion 9 is supported by the same shaft 6 to which cylindrical gear 5 is fitted, and which, as stated, is in turn supported by bearings 7, 8 housed inside respective seats 12, 13 formed respectively in a first inner supporting element 14 and in a first lateral wall 15. In addition to first lateral wall 15, casing 2 also comprises a second lateral wall 16, a third wall 17, a fourth wall 18, and, to complete the box structure of casing 2, a further two lateral walls not shown in Figures 1-3. Second lateral wall 16 comprises an opening 19 through which pinion 34 meshes with cylindrical gear 5; and third and fourth walls 17 and 18, which are substantially parallel and specular in relation to each other, comprise respective seats 20,21 and 22,23 for housing the bearings supporting the countershafts. In Figure 1, shaft 6, to which hypoid pinion 9 is fitted, extends through a seat 24 formed in a second inner supporting element 25, the function of which is explained in detail later on; and driven shaft 11, to which bevel ring gear 10 is fitted, rests on two known bearings 26, 27 housed inside seats 20, 22 on respective third and fourth walls 17, 18. In the Figure 1 two-stage embodiment, motion "enters" casing 2 via first reduction stage 3 defined by pinion 34 meshing with cylindrical gear 5, "passes" through second reduction stage 4 defined by hypoid pinion 9 meshing with bevel ring gear 10, and "leaves" from driven shaft 11 which drives a user element (not shown). Hypoid pinion 9 is therefore supported by a shaft 6 in turn supported by two bearings 7, 8 on either side of pinion 9, so that the stress exerted on pinion 9 is adequately distributed, thus eliminating the drawbacks mentioned previously. Figure 3 shows seats 20-23 employed differently as compared with Figure 1, and whereby the same casing 2, which in the Figure 1 embodiment houses only two reduction stages 3, 4, may also accommodate a further third reduction stage 28 defined by a pinion 30 meshing with a gear 29. With no alterations to opening 19 and seat 20 by which motion respectively "enters" and "leaves" the casing (or vice versa), the same casing 2 may therefore be used selectively for a reducer with two stages 3, 4 or three stages 3, 4, 28, thus enabling considerable saving in terms of production and storage cost. In the three-stage angular reducer shown in Figure 3, specular seats 21, 23, which are not used in the Figure 1 embodiment, now serve to support the shaft supporting pinion 30, which shaft is also integral with bevel ring gear 10 meshing with bevel pinion 9; and the second inner supporting element 25, formed in one piece with casing 2 (Figure 1), supports a bearing 33 (Figure 3), so that shaft 6 (shorter in Figure 3 than in Figure 1) rests on bearing 7 on one side and on bearing 33 on the other. In this case, too, bearings 7 and 33 are located on either side of bevel pinion 9 to better distribute the stress on the bearings and so prevent vibration within the system as a whole. When switching from the two-stage 3,4 reducer (Figure 1) to the three-stage 3,4,28 design (Figure 3) by replacing a number of elements in the gear train, the distance between axes K and L therefore remains unchanged. The casing described provides not only for housing two or three reduction stages, but also for considerable advantages in terms of the noise level of the system as a whole, by virtue of two bearings being provided on either side of the hypoid pinion.

Claims: A multistage angular reducer (1) comprising: 1. A multistage angular reducer (1) comprising: a casing (2); a drive shaft (35); a driven shaft (11) connected to a user element; and a number of reduction stages (3, 4, 28) housed inside of said casing (2) between said drive shaft (35) and said driven shaft (11), wherein at least one stage (3, 4, 28) is defined by a pair of gears defined by a bevel pinion (9) and a bevel ring gear (10); and wherein said casing (2) is designed to selectively house two (3, 4) or three (3, 4, 28) reduction stages, while maintaining unchanged, when switching from said two reduction stages (3, 4) to said three reduction stages (3, 4, 28) or vice versa, the mutual positions of an axis (K) of the drive shaft (35) and an axis (L) of the driven shaft (11); said multistage angular reducer (1) being characterized by the fact that three coaxially aligned supporting elements (14, 25, 15) are provided within said casing (2), said supporting elements (14, 25, 15) being integral with said casing (2) and being able to selectively support by means of two of said supporting elements (14, 25,15) a first and a second shaft (6) of said bevel pinion (9) corresponding, respectively, to two reduction stages (3, 4) and three reduction stages (3, 4, 28), so that in both configurations (3, 4; 3, 4, 28) a pair of said supporting elements (14, 25, 15) supporting said shaft (6) are located on axially opposite sides of said bevel pinion (9). An angular reducer (1) as claimed in Claim 1, wherein said casing (2) comprises two walls (17, 18) substantially parallel to each other and each having two seats (20, 21; 22, 23); and further two walls (15, 16) substantially parallel to each other and each having one seat (13, 19). An angular reducer (1) as claimed in Claim 2, wherein, when said casing (2) houses said two reduction stages (3, 4), said bevel pinion (9) is a hypoid bevel pinion; the seat (13) of one of said supporting ments (15) receiving a bearing (8) for supporting a first end of said first shaft (6), while a second end of said first shaft (6) is supported by said supporting element (14) by means of a bearing (7). An angular reducer (1) as claimed in Claim 2, wherein, when said casing (2) houses said three reduction stages (3, 4, 28), a first end of said second shaft (6) is supported by said supporting element (25) by means of a bearing (33), while a second end of said second shaft (6) is supported by said inner supporting element (14) by means of a bearing (7). An angular reducer (1) as claimed in Claim 1, wherein the stage (4) defined by a bevel pinion (9) and by a bevel pinion gear (10) is not the first in the gear train.

Inventors: COGNIGNI ENZO, DEPIETRI PIETRO, COGNIGNI, ENZO, DEPIETRI, PIETRO
Applicants: BONFIGLIOLI RIDUTTORI SPA, BONFIGLIOLI RIDUTTORI S.P.A.
Application year: 1997
Main classification: F16H1
IPC codes: F16H1, F16H57