DESCRIPTION

Field of the invention

The present invention relates to a device for the selective transmission of torques.

Description of the prior art

As well known, in mechanical is very frequent the need for devices capable of transmitting torques and/or angular speeds between different components of a kinematical chain, such as between a drive shaft and a wheel, or between an actuator and a robotic joint.

It is also often required that these devices can allow to decide whether to connect or disconnect the components between which this rotary motion transmission is to be carried out, for example for safety reasons or to selectively connect a source of drive torque to different outputs (eg automotive clutches) .

Moreover, since these devices substantially affect the overall weight and reliability of a mechanical transmission, one of the essential objectives in their design is to identify simple solutions, which make use of few components, and which at the same time guarantee high efficiency in the transmission of motion. A possible device of this type is disclosed in

EP0213291, wherein a free-wheel device is claimed that comprises a plurality of elements ( "sprags") having clamping surfaces suitable for connecting a guide element and a guided element by friction, so as to transmit a torque, both in one sense and in the other, between the two elements.

However, this device does not allow in any way the selective or simultaneous connection of the guide element to more than one guided element, for example preventing the use of the same actuator for more shafts or more joints.

Moreover, the device is complex and not very reliable, above all due to the fragility of the elastic tabs, which are necessary to keep the guide element and the guided element disconnected from each other until a sufficient force is applied to it.

The same considerations made by EP0213291 are also valid for devices described in AT396972 and US2003183473.

Summary of the invention

It is therefore a feature of the present invention to provide a device for the selective transmission of torques that allows to transmit a rotary motion, in a simple and effective manner, between two elements of a kinematic chain.

It is also a feature of the present invention to provide such a device which allows the two elements to be connected and disconnected according to requirements. It is still a feature of the present invention to provide such a device which allows to connect a rotating input element, selectively or simultaneously, to a plurality of output elements.

These and other objects are achieved by a device for the selective transmission of torques according to claims from 1 to 9.

Brief description of the drawings

Further characteristic and/or advantages of the present invention are more bright with the following description of an exemplary embodiment thereof, exemplifying but not limitative, with reference to the attached drawings in which:

— Fig. 1 shows a perspective view of a first exemplary embodiment of the device for the selective transmission of torques, according to the present invention, where it is present a single receiving element and a single rotating element;

— Fig. 1A shows a front view of the exemplary embodiment Fig. 1;

— Fig. IB shows a front view of a variant of the exemplary embodiment Fig. 1, wherein two single rotating elements are provided symmetrically arranged;

— Fig. 1C shows a front view of a variant of the exemplary embodiment Fig. 1, wherein it is present a "C" type rotating element;

— Fig. 2 shows a perspective view of a second exemplary embodiment of the device for the selective transmission of torques, according to the present invention, wherein two receiving elements and a "S" type rotating element are provided;

— Fig. 2A shows a front view of the exemplary embodiment Fig. 2;

— Fig. 2B shows a front view of a variant of the exemplary embodiment Fig. 2, wherein two "S" type rotating elements are provided symmetrically arranged;

— Fig. 2C shows a front view of a variant of the exemplary embodiment Fig. 1, wherein it is present a single rotating element and a "C" type rotating element ;

— Fig. 3 shows a perspective view of a third exemplary embodiment of the device for the selective transmission of torques, according to the present invention, wherein two receiving elements and two rotating elements are provided arranged on a single shaft;

Fig. 3A shows a perspective view of the connection means of the exemplary embodiment of Fig. 3; Fig. 4 shows a perspective view of a fourth exemplary embodiment of the device for the selective transmission of torques, according to the present invention, wherein two receiving elements and four rotating elements are provided arranged on two shafts;

— Fig. 5 shows a perspective view of a fifth exemplary embodiment of the device for the selective transmission of torques, according to the present invention, wherein four receiving elements and two rotating elements are provided arranged on a single shaft;

— Fig. 6 shows a perspective view of a sixth exemplary embodiment of the device for the selective transmission of torques, according to the present invention, wherein four receiving elements and four rotating elements are provided arranged on two shafts;

— Fig. 7 shows, in a front view, a possible mechanical embodiment of the device for the selective transmission of torques, according to the present invention;

— Fig. 7A shows a cross sectional view of the exemplary embodiment of Fig. 7;

— Figs. 8A, 8B and 8C show, respectively, a perspective view, side and front of the connection means usable in the exemplary embodiment of Fig.

7.

Description of a preferred exemplary embodiment

With reference to Figs. 1 and 1A, in a first exemplary embodiment, the device 100 for the selective transmission of torques comprises an inlet arranged to provide an inlet torque Q and an outlet arranged to express an outlet torque 7 .

In particular, the inlet comprises a transmission element 105, having annular shape, arranged to rotate with speed w about a rotation axis x, whereas the outlet comprises a receiving element 110, also having annular shape, arranged to rotate with speed ΰ ₁ about the same rotation axis x.

The device 100 comprises then connection means 120 arranged to pass between a disengagement configuration and an engagement configuration.

With particular reference to Fig. 1A, the connection means 120 comprises a rotating element 125 engaged to the transmission element 105 and arranged to rotate about a rotation axis x' for causing the device 100 to pass between the engagement configuration and the disengagement configuration. In Fig. 1A the rotating element 125 is shown with a continuous line in the engagement configuration and with a dotted line in the disengagement configuration. In particular, in the exemplary embodiment of Fig. 1 and 1A, the rotating element 125 is a single rotating element, i.e. having a first semi-circular end and a second end with a logarithmic spiral-shaped profile.

Thanks to this particular geometry, in the engagement configuration the rotating element 125 is clamped by friction to the inner wall of the receiving element 110 when the transmission element 105 rotates counter-clockwise, allowing to transfer both the inlet torque Q and the angular speed w from the inlet to the outlet. In the engagement configuration, therefore, the receiving element 110 rotates with angular speed ΰ ₁ = w about its axis x and expresses an outlet torque

Ti = Q.

With respect to other geometries, the logarithmic spiral geometry allows a transmission most effective of the angular moment, since the force of friction given by the clamping increases with the rotation: this causes the generation of a totally stable connection between the transmission element 105 and the receiving element 110 until the rotating element 125 is not rotated about its rotation axis x' to pass to the disengagement configuration.

In Fig. IB a variant of the device 100 of Fig. 1 is shown, wherein two single rotating elements 125 and 125' are provided, similar to those of Fig. 1A. The two elements 125 and 125' are symmetrically arranged with respect to the axis x so that, in the engagement configuration, the rotating element 125 is clamped by friction to the inner wall of the receiving element 110 when the transmission element 105 rotates counter-clockwise, and the rotating element 125' is clamped by friction to the inner wall of the receiving element 110 when the transmission element 105 rotates clockwise. Such exemplary embodiment allows therefore to transfer both the inlet torque Q and the angular speed w from the inlet to the outlet in both the rotation directions.

In Fig. 1C a variant of the device 100 of Fig. 1 is shown, wherein a type "C" rotating element 125 is provided, i.e. having the ends both with a logarithmic spiral-shaped profile and symmetrical to each other with respect to the rotation axis c' . By rotating this rotating element 125 and bringing it between two positions, as shown in Fig. 1C with a continuous line and with a dotted line, it is possible to transfer, as in the embodiment of Fig. IB, the inlet torque Q and the angular speed w in both the rotation directions, but using only one rotating element 125.

In the figures 2 and 2A a second exemplary embodiment of the device lOOis shown, wherein an inlet, similar to that of Fig. 1, and two outlets are provided arranged to express respective outlet torques 7 and T ₂ . The two outlets comprise respective receiving elements

110 and 110' , both having annular shape, concentric to each other and arranged to rotate about the axis x with angular speeds ¾ and ϋ ₂ .

In this exemplary embodiment, the connection means 120 comprises a "S" type rotating element 125, i.e. having the ends both with a logarithmic spiral-shaped profile and antisymmetric to each other with respect to the rotation axis x' .

This allows that, in the engagement configuration, the rotating element 125 is clamped by friction to the inner wall of the receiving element 110 when the transmission element 105 rotates in a first direction and that it is clamped to the external wall of the receiving element 110' when the transmission element 105 rotates in the opposite direction. In the first case, we will have ΰ ₁ = w, ΰ ₂ = 0, T ₁ = Q , T ₂ = 0, whereas in the second we will have ΰ ₁ = 0, ΰ ₂ = w, 7 = 0, T ₂ =

Q.

Clearly, the rotating element 125 can be located in order to be clamped in the desired direction.

In the exemplary embodiment of Fig. 2B, instead, two "S" type rotating elements 125 and 125' are provided arranged symmetrically with respect to the axis x . The way the two elements 125 and 125' are arranged in Fig. 2B, when, in the engagement configuration, the transmission element 105 rotates counter-clockwise the rotating element 125 is clamped by friction to the inner wall of the receiving element 110 and, at the same time, the rotating element 125' is clamped to the external wall of the receiving element 110' . Conversely, it occurs when the transmission element 105 rotates clockwise. This way, the inlet can transmit both the torque and the angular speed to both the outlets at the same time and in both the directions of rotation.

In particular, in the engagement configuration we will have Q = T ₁ + T ₂ and w=ϋ ₁ =ϋ ₂ · It is obviously possible to arrange only one of the rotating elements 125, 125' in contact with an outlet, leaving the other in a position not engaged, so that the device 100 acts similarly to the exemplary embodiment of Fig. 2A.

In Fig. 2C a further variant of the exemplary embodiment of Fig. 2 is shown, wherein two rotating elements 125 and

125' are provided.

In particular, each "C" type rotating element can be arranged in the three positions shown in the figure with a continuous line and a dotted line:

- in contact with a receiving element with the logarithmic spiral profile in a first direction;

- in contact with a receiving element with the logarithmic spiral profile in the opposite direction; not in contact with a receiving element.

Therefore, suitably positioning the rotating elements 125 and 125' , it is possible to connect the inlet alternatively to the first outlet, to the second outlet, to both the outlets or to none, both in a direction of rotation and in the another one.

Although not shown in the figure for simplicity, it is meant that here are described all the exemplary embodiments in which the variants of the rotating elements 125 and 125' shown in the preceding figures are combined. It is in fact possible to replace each rotating element 125 or 125' with a rotating element single type, "C" type or "S" type, positioning it in the most appropriate way, in order to allow the selective transmission of the torque Q and of the angular speed w to the outlet or to the outlets desired.

In Fig. 3 a further exemplary embodiment of the device lOOis shown, wherein there are two receiving elements 110 and 110', and where the connection means comprises a shaft 126 on which two rotating elements 125a and 125b are arranged. The shaft rotates about its rotation axis c', in order to cause the rotation of the rotating elements 125a and 125b about this axis.

As best seen in Fig. 3A, the two elements 125a and 125b can be of various type, for example one "C" type and one "S" type. Alternatively, they can be of the same type, but having opposite directions. The shaft 126 can translate along the axis c', in order to dispose in the engagement position one rotating element 125 or the other one or none of the two.

It is also possible to place more than two rotating elements 125 on the same shaft 126, of each type and with each aforementioned direction, to allow a multiplicity of motion transmission configurations, by translating the shaft 126.

In Fig. 4 an exemplary embodiment of the device 100 is shown which joins the embodiments of figures 2 and 3, providing that there are 4 rotating elements 125a, 125b, 125a and 125b', mounted on two shafts 126 and 126' arranged in a symmetrical way with respect to the axis x . This way, it is possible to further increase the possible motion transmission configurations between inlet and outlets, combining the translation of the shafts 126 and 126' along the respective axes x' and x" and disposing many rotating elements 125 in different angular positions.

In the figures 5 and 6 other exemplary embodiments of the device 100 are shown that provide the presence of 4 receiving elements 110a, 110b, 110a', 110b', i.e. 4 outlets. In Fig. 5 a shaft 126 is provided, whereas in Fig. 6 two shafts 126 and 126' are provided.

By appropriately using the many combinations mentioned above, the embodiments of the device 100 shown in Figures 5 and 6 allow the element to be connected to each of the receiving elements 110 or to several receiving elements 110, both in one direction and in the other.

As evident, is also possible to provide devices 100 for the selective transmission of torques that have any number of outlets, and to connect the inlet to a predetermined number of such outlets, simply combining and appropriately arranging the connection means 120 described in the embodiments of Figs. 1 to 6.

In the figures 7 and 7A a possible mechanical embodiment of the device 100 is shown. As shown, in this exemplary embodiment the connection means 120 comprises a plurality of shafts 126, on each of which a respective "C" type connecting element 125 is arranged.

In Figs. 8A to 8C, the connection means 120 usable in the device 100 of Figs. 7 and 7A is shown.

In particular, Fig. 8C clearly shows that it is a "C" type rotating element 125, whereas Figs. 8A and 8B show that the element comprises a groove 127 able to allow a more stable assembly of the rotating element to the inside the device 100 of Figs. 7 and 7A.

Furthermore, in Fig. 8C some possible geometric parameters are shown, such as the opening angle a = 60 and the curved logarithmic spiral shape, marked with thicker line. In particular, this curve has equation: R = R ₀ *e ^A (0.158391919*a)

where R ₀ is shown graphically in the figure.

The foregoing description some exemplary specific embodiments will so fully reveal the invention according to the conceptual point of view, so that others, by applying current knowledge, will be able to modify and/or adapt in various applications the specific exemplary embodiments without further research and without parting from the invention, and, accordingly, it is meant that such adaptations and modifications will have to be considered as equivalent to the specific embodiments. The means and the materials to realise the different functions described herein could have a different nature without, for this reason, departing from the field of the invention. It is to be understood that the phraseology or terminology that is employed herein is for the purpose of description and not of limitation .