Mechanical torque limiting device

Abstract

. Mechanical torque limiting device (1 ) comprising a containment body (2) comprising an inner cavity (3) open at an insertion mouth (30) a pack of discs (4) entirely housed in said inner cavity (3) and structured for limiting said transferable mechanical torque to a maximum mechanical torque, the pack of discs (4) comprising a plurality of first discs (5) and a plurality of second discs (6) wherein said containment body (2) comprises one or more through discharge openings (22), wherein each through discharge opening (22) comprises a respective inlet mouth (24) facing said inner cavity (3), and wherein each respective inlet mouth (24) is arranged upstream of said coupling portion (8) of the containment body (2) mechanically coupled with said first discs (5)

Description

[0001] DESCRIPTION

[0002] Title: MECHANICAL TORQUE LIMITING DEVICE

[0003] Technical field of the invention

[0004] The present invention concerns a mechanical torque limiting device and a system for motion transmission comprising the aforementioned limiting device.

[0005] State of the art

[0006] US2015033892A1 describes a gearbox comprising a gear wheel which is connected / disconnected to / from a drive shaft by a mechanical torque limiting device with discs mounted on the latter.

[0007] Summary of the invention

[0008] By 'substantially perpendicular' in relation to geometric elements (such as lines, planes, surfaces, etc.) it is meant that these elements form an angle within the range 90°+ / -15°, preferably 90°+ / -10°.

[0009] By 'substantially parallel' in relation to the aforementioned geometric elements it is meant that these elements form an angle within the range 5°, preferably 0°+ / -10°.

[0010] In the aforementioned context of disc mechanical torque limiting devices which exploit the friction between the discs for limiting a torque transferable from the engine to the user so that it does not exceed a maximum torque, the Applicant has considered it advantageous to be able to control the value of the torque maximum transferable in a stable and long-lasting way.

[0011] In fact, once the maximum torque value has been adjusted for a given limiting device, for example at the end of the production process (e.g. during the product approval phase) and depending on the intended use, it is important that this maximum torque remains constant over time (except for voluntary interventions).

[0012] The Applicant has therefore faced the problem of creating a mechanical torque limiting device which is stable over time in terms of maximum torque and at the same time structurally simple and / or economical.

[0013] According to the Applicant, the aforementioned problem is solved by a mechanical torque limiting device according to the attached claims and / or having one or more of the following features.

[0014] According to one aspect, the invention relates to a mechanical torque limiting device for limiting a mechanical torque transferable from a first shaft to a second shaft or vice versa. The device comprises:

[0015] - a containment body structured to be interposed between said first shaft and said second shaft for mechanically connecting to each other said first and second shafts, said containment body comprising an inner cavity open at an insertion mouth;

[0016] - a pack of discs entirely housed in said inner cavity and structured for limiting said transferable mechanical torque to a maximum mechanical torque, the pack of discs comprising a plurality of first discs and a plurality of second discs arranged in succession along a central axis.

[0017] Preferably said containment body comprises a coupling portion, said first discs being mechanically coupled to said containment body at said coupling portion for rigidly rotating with said containment body around said central axis.

[0018] Preferably said inner cavity is conformed to allow an insertion of said second shaft into said inner cavity through said insertion mouth along an insertion direction, said second discs being structured for mechanically coupling with said second shaft (only) when inserted into said inner cavity.

[0019] Preferably said containment body comprises one or more through discharge openings.

[0020] Preferably each through discharge opening comprises a respective inlet mouth facing said inner cavity.

[0021] Preferably each respective inlet mouth is arranged upstream of said coupling portion (with respect to said insertion direction).

[0022] The terms "upstream", "downstream" and similar refer to an oriented direction of said insertion direction which typically goes from the insertion mouth to the pack of discs.

[0023] According to the Applicant, the aforementioned through discharge openings having their respective inlet mouths (further to the insertion mouth) facing the inner cavity, allow to realize a communication between the inner cavity and the outside of the containment body useful for the discharge of any contaminating and / or fouling agents possibly drawn into the inner cavity through the insertion mouth, so as to avoid their accumulation in the inner cavity.

[0024] Thanks to the inlet mouths arranged upstream of the coupling portion (i.e. arranged before the coupling portion proceeding in a direction consistent with the direction of insertion of the second shaft) it is also possible to unload (e.g. also thanks to the rotary motion of the containment body around the central axis) the aforementioned contaminating and / or fouling agents before these agents can reach the coupling portion and therefore the pack of discs.

[0025] In other terms, thanks to the discharge openings having their respective inlet mouths arranged as described above, vent ducts are realized, which are properly arranged so that the agents, possibly drawn from the insertion port, can find a privileged flow direction (e.g. with less resistance) exiting the inner cavity of the containment body rather than preferring further infiltration towards the pack of discs.

[0026] In this way it is possible to preserve the pack of discs from direct contact with such contaminating and / or fouling agents, keeping under control the respective limiting qualities of the maximum transferable torque. The Applicant has in fact found that in case the pack of discs is wet by the aforementioned contaminating and / or fouling agents, typically lubricating agents (e.g. oil), these, due to the respective variation in chemicalphysical properties, for example due to ageing, temperature variation, etc., can lead to an uncontrollable, and in general unpredictable, variation in the friction forces between the discs (for the same compression force exerted on the discs), with consequent uncontrolled variation in the maximum transferable torque.

[0027] The present invention in one or more of the above aspects may presentone or more of the following preferred features.

[0028] Preferably said inner cavity is axially blind (e.g. with reference to the central axis). In other words, the containment body preferably comprises a back wall (axially opposite to said insertion mouth) which helps to delimit the inner cavity. Preferably the back wall is devoid of respective through openings of such dimensions as to allow the second shaft to pass through them. In this way the inner cavity is shaped to house said second shaft in such a way that a drive section of the second shaft (for example a section of the second shaft including an interface for transmission of motion to mechanical parts arranged in cascade to the second shaft) remains external to the inner cavity and placed on the opposite side of the insertion mouth with respect to the inner cavity, when the second shaft is housed in the inner cavity (as better described below). In this way it helps to locate any leakage of contaminating and / or fouling agents essentially only at the insertion mouth, further improving the protection of the pack of discs since the contaminating agents, in their possible leakage towards the pack of discs from the insertion mouth, they meet the inlet mouths of the discharge openings before the pack of discs.

[0029] Preferably each respective inlet mouth is arranged externally to said coupling portion. In this way the protection of the pack of discs from contaminants / fouling agents is improved.

[0030] Preferably each respective inlet mouth is angularly equally distributed about said central axis with respect to remaining inlet mouths. In this way the discharge effectiveness is spatially uniformed.

[0031] Preferably said containment body comprises an end face, preferably extending on a plane (substantially) perpendicular to said central axis. Preferably said insertion mouth is made at said end face.

[0032] Preferably one or more of the through discharge openings each comprises (more preferably are made of) a respective groove made onto said end face. Preferably each groove develops from said insertion mouth to an external surface of said containment body. In this way the openings are made in a constructionally simple way (e.g. by milling). In this embodiment, a portion of the first shaft to which the containment body is fixed can act as a cover for these grooves, thus creating, at each groove, an entirely closed channel (as better described below). Furthermore, in this way, the discharge openings are arranged in close proximity to (contiguous to) the insertion mouth, further facilitating discharge.

[0033] In one embodiment (also possibly in combination with the aforementioned grooves) one or more of the through exhaust openings each comprise (more preferably are made from) a respective through hole. Preferably each respective inlet mouth is interposed (arranged in an intermediate position) between said insertion mouth and said coupling portion. In this way, the creation of the containment body is facilitated (e.g. being able to use the same tools for the through holes of the drainage channels as well as for any holes designed to accommodate means of fastening the device and / or separate parts of the containment body). Preferably each through discharge opening has a respective main development having at least one radial component with respect to said central axis, more preferably purely radial. In this way the discharge of agents is facilitated.

[0034] Preferably said containment body is structured for being mechanically rigidly coupled to said first shaft, more preferably at said end face. In this way the fixing is facilitated.

[0035] Preferably said coupling portion has a respective main development (substantially) cylindrical about said central axis. In this way the housing of the pack of discs is facilitated.

[0036] Preferably said containment body is (totally) sealed with the exception of (only) said insertion mouth and of said inlet mouths. By "(totally) sealed" it is meant that the containment body has no openings further than the insertion mouth and the inlet mouths of the through discharge openings and / or that these further openings, if present, are (directly) sealed. In this way the discs are further protected. For example (in addition to the insertion mouth), only the aforementioned discharge openings passing through for the discharge of agents are expected to be kept free, thus encouraging discharge only through them.

[0037] Preferably said coupling portion is devoid of through openings. Preferably said coupling portion is entirely structurally contiguous. In this way the device is robust and / or the protection of the pack of discs is further improved.

[0038] In one embodiment, said device comprises a gasket (e.g. in elastically flexible polymeric material) fixed to said containment body and structured (e.g. shaped) for being interposed (in contact with seal) between said containment body and said second shaft when inserted in the inner cavity.

[0039] Preferably said gasket is arranged in intermediate position between said coupling portion and said inlet mouths. In this way the protection of the pack of discs is further improved.

[0040] Preferably each first disc comprises one or more respective projections (more preferably a plurality of projections circumferentially equally distributed with respect to said central axis) which protrude radially externally from the first disc with respect to said central axis.

[0041] Preferably said coupling portion comprises one or more grooves (more preferably a plurality of grooves circumferentially equally distributed with respect to said central axis) facing said inner cavity. Preferably each groove of said containment portion has a respective main development line (substantially) parallel to said central axis.

[0042] Preferably said one or more projections of each first disc each engage one (and only one) respective groove of said one or more grooves of said coupling portion. Preferably an inner surface of said coupling portion is substantially counter-shaped to a radially external profile of said first discs. In this way, the rigid rotational coupling between the containment body and the first discs is realized in a structurally simple manner. Preferably each first and second disc has annular shape comprising a respective central through opening. Preferably said respective central through openings are coaxial to said central axis. In this way, an empty volume is realized inside the pack of discs which is advantageous for housing the second shaft (at least an end portion of the second shaft), as described below, keeping the device compact.

[0043] Preferably each second disc comprises one or more respective projections (more preferably a plurality of projections circumferentially equally distributed with respect to said central axis) which protrude radially internally from the second disc with respect to said central axis. Preferably said one or more respective projections of each second disc are arranged along an edge of the respective central through opening of the respective second disc. In this way they are conveniently arranged to gear with the second shaft, when inserted inside the pack of discs.

[0044] Preferably, said first and second discs are alternated to each other along the central axis. In this way the forces (e.g. friction) are distributed evenly during use.

[0045] Preferably said first discs are made of metallic material, for example steel.

[0046] Preferably each second disc comprises a layered structure. Preferably each second disc comprises a support disc, preferably made of metallic material, for example steel, and a first and a second coating layer arranged at axially opposite parts of (e.g. glued to) said support disc.

[0047] Preferably (only) the support disc of each second disc is equipped with said one or more respective projections of the second disc. In this way the second disc remains structurally simple.

[0048] Preferably each coating layer comprises, more preferably is made of, a friction material. This material has proven to be particularly advantageous in terms of friction forces, and / or stability of such friction forces, developable between the discs (which in turn determine the maximum transferable mechanical torque) and / or wear resistance, particularly in synergy with the use of a pack of dry discs (better described below), for example compared to simple direct steel-to-steel contact.

[0049] Preferably said first and second discs are arranged in direct contact with each other (e.g. the first discs directly contacting a respective coating layer of the directly preceding and / or subsequent second disc). In this way the friction forces between the discs develop in the desired way.

[0050] Preferably said device comprises an adjustment system structured for adjusting a compressive force acting on said pack of discs (more preferably - substantially - parallelly to the central axis).

[0051] Preferably said adjustment system comprises an elastic element, operatively interposed between said containment body and an extremal disc of said pack of discs. Preferably the elastic element is structured to said pack of discs in compression against said containment body. Preferably said adjustment system comprises an adjustment element, structured for adjusting a degree of compression of said elastic element against said extremal disc. In this way it is possible to adjust the maximum mechanical torque.

[0052] According to another aspect, the invention relates to a motion transmission system (from the first shaft to the second shaft or vice versa) comprising the mechanical torque limiting device according to the present invention.

[0053] Preferably said transmission system comprises said first shaft. Preferably said containment body is rigidly fixed (more preferably sealed) to said first shaft, preferably for rigidly rotating with said first shaft around an axis of said first shaft. Preferably said insertion mouth faces towards (in a proximal position to) said first shaft (said end face preferably being in contact with the first shaft). Preferably the axis of the first shaft coincides with said central axis. In this way the system is highly rational and simple in terms of motion transmission from the first shaft to the device.

[0054] Preferably said transmission system comprises said second shaft. Preferably said second shaft is inserted into said inner cavity and mechanically coupled to said second discs for rigidly rotating together with said second discs about said central axis (said first shaft being suitably shaped for leaving free access to the insertion mouth to allow positioning of the second tree, as better described below).

[0055] Preferably said system comprises a main body having a housing cavity, more preferably open at a housing mouth.

[0056] Preferably said main body comprises a separation septum which separates said housing cavity into a first and a second sub-cavity.

[0057] Preferably said separation septum comprises a communication mouth between said first and second subcavity.

[0058] Preferably said first shaft is at least partially arranged at said communication mouth, closing off (with sealing) said communication mouth. In other words, the first shaft is arranged at least partially across the first and second sub-cavity.

[0059] Preferably said limiting device is entirely housed in said first sub-cavity. Preferably said first sub-cavity is devoid of lubricating agents (preferably contains only air). In this way, a chamber is realized, i.e. the first subcavity, in which it is possible to house the limitation device, thus allowing the discharge openings to discharge into the first sub-cavity any contaminating agents that have penetrated the inner cavity through the insertion mouth (typically in communication with the second sub-cavity, which instead contains lubricating agents for lubricating at least the portion of the first shaft housed therein), while at the same time preventing other contaminating agents from entering the inner cavity by going up the discharge openings.

[0060] Preferably said first shaft is a gear wheel.

[0061] Preferably said containment body is fixed (more preferably directly) to said gearwheel (preferably at a lateral face of the gear wheel). In this way the limiting device is coupled to the first shaft in a simple way.

[0062] Preferably said transmission system comprises a worm screw mechanically meshed to said first shaft (to said gear wheel), more preferably at a portion of said first shaft (of said gear wheel) housed in said second sub-cavity.

[0063] Preferably said second sub-cavity is filled with a lubricating agent (for lubricating the portion of the first shaft housed therein, for example, and preferably, at the worm screw-first shaft mechanical coupling).

[0064] Preferably said communication mouth has cylindrical symmetry about said central axis / said axis of said first shaft. In this way the system is rotationally balanced.

[0065] Preferably said first shaft (said gear wheel) is rotationally fixed to said main body.

[0066] Preferably said second shaft is at least partially housed in said housing cavity. In this way the compactness of the system is further improved.

[0067] Preferably said first shaft (called gear wheel) comprises a respective central through opening. Preferably said insertion mouth is arranged at an edge of, more preferably in communication with, said central through opening of the first shaft (of the gear wheel). In this way, access is created to the insertion mouth for easily inserting the second shaft

[0068] Preferably said second shaft develops through said first shaft (said gear wheel) at said central opening passing through the first shaft (of the gear wheel). In this way the system is compact.

[0069] Preferably said gasket of said device, said containment body (e.g. at least said coupling portion and at least one remaining portion of the containment body, arranged downstream of said coupling portion, preferably comprising the aforementioned back wall), and said second shaft realize, at the inner cavity, a sealed chamber which entirely encloses said pack of discs. In this way the protection of the disc pack is incremented. Preferably said inner cavity (preferably at least said sealed chamber) is devoid of lubricating agents. In other words, the disc stack preferably takes advantage of the friction forces that are formed between the dry stacked discs. In this way, by completely eliminating the presence of any lubricating agent in direct contact with the disc pack, it is easier to maintain stable operating dynamics over time, for example in terms of the set mechanical torque threshold.

[0070] Preferably, said transmission system comprises a respective gasket fixed to said separation partition at said communication mouth. Preferably said respective gasket is placed in contact between said first shaft (more preferably said gear wheel) and said separation partition (the first shaft rotating in sliding motion on said gasket of the system). In this way, the seal created by the first shaft at the communication mouth is improved. In one embodiment, said transmission system comprises a respective further gasket (e.g. in elastically flexible polymeric material) fixed to said first shaft (preferably said gearwheel) at said central passing opening of said first shaft (preferably said gear wheel). Preferably said respective further gasket is placed in contact between said first shaft (preferably said gear wheel) and said second shaft. In this way, any leakage of the lubricating agents from the second sub-cavity to the inner cavity of the device is further limited.

[0071] In one embodiment, said transmission system comprises the aforementioned respective further gasket and incorporates the aforementioned embodiment of the limitation device also equipped with a gasket. In other words, the seals are doubled, improving the protection of the disc pack. In this way the inlet mouths are arranged in an intermediate position between said respective further gasket of the transmission system and said gasket of the limiting device. This in turn allows the leakage of the lubricating agents towards the disc pack to be further limited. In fact, in this way it is possible to create a region of the system delimited by the two aforementioned gaskets in which the agents possibly drawn through the respective further gasket of the system in the direction of the pack of discs are slowed down by the gasket of the limiting device, remaining more at the mouths of the discharge openings, further facilitating unloading. Preferably said second shaft comprises one or more respective grooves (more preferably a plurality of grooves circumferentially equally distributed with respect to an axis of said second shaft) made on an external surface of said second shaft. Preferably each groove of said second shaft has a respective main development line (substantially) parallel to an axis of said second shaft.

[0072] Preferably said second shaft is inserted into said respective central openings passing through said first and second discs (through the insertion mouth).

[0073] Preferably said one or more projections of each second disc each engage one (and only one) respective groove of said second shaft. Preferably said external surface of said second shaft at said end portion is substantially counter-shaped to a radially inner profile of said second discs. In this way, the rigid rotational coupling between the second shaft and the second discs is achieved in a structurally simple way.

[0074] Preferably said axis of said second shaft coincides with said central axis (and preferably also with the axis of the first shaft). In this way the motion transmission is rational.

[0075] Preferably said second shaft comprises an end portion comprising said one or more respective grooves of said second shaft. Preferably said end portion is (entirely) housed in said inner cavity.

[0076] Preferably said mechanical torque limiting device can be reversibly rigidly fixed to said first shaft (to said gear wheel). Preferably said housing mouth is arranged at said first sub-cavity. In this way the limiting device is easily accessible, for example for maintenance and / or replacement of the torque limiting device, with limited interventions on the motion transmission system (e.g. without the need to dismantle the mechanical transmission parts of motion of the first and / or second shaft, for example without decoupling the worm screw and the gear wheel).

[0077] Brief description of the figures

[0078] Figure 1 schematically shows a longitudinal section of part of a motion transmission system according to the present invention; figure 2 schematically shows a further longitudinal section of part of the motion transmission system; figures 3 and 4 schematically show two longitudinal and transversal sections, at different heights, of a subportion of the part of the system in figure 2, figure 5 shows in a purely schematic way a section of the motion transmission system according to the present invention.

[0079] Detailed description of some embodiments of the invention

[0080] The features and the advantages of the present invention will be further clarified by the following detailed description of some embodiments, presented by way of example and not as a limitation of the present invention, with reference to the attached figures.

[0081] In the figures, with the number 1 it is generally indicated a mechanical torque limiting device for limiting a mechanical torque that can be transferred from a first shaft 90 to a second shaft 91 (e.g. direct motion) or vice versa (e.g. retrograde motion). Ideally, in the embodiments shown, the first shaft 90 ideally belongs to a drive side (e.g. it is a drive shaft) of a machine (not shown) incorporating the limiting device 1 , while the second shaft 91 belongs to a user side.

[0082] In one alternative embodiment (not shown), what has been described above can be specularly reversed, i.e. the first shaft can belong to the user side and the second shaft to the motor side.

[0083] The device 1 comprises a containment body 2 structured to be placed between the first shaft 90 and the second shaft 91 for mechanically connecting the first 90 and the second shaft 91 to each other. Exemplarily the containment body 2 is structured for being mechanically rigidly coupled to the first tree 90 (as better described below).

[0084] The containment body 2 comprises an inner cavity 3 open at an insertion mouth 30. For example, the inner cavity 3 is shaped to allow insertion of the second shaft 91 into the inner cavity (as for example shown in figure 2 in a completely inserted position) though the insertion mouth 30 along an insertion direction 101 (shown for example in figure 1).

[0085] The device 1 comprises a pack of discs 4 entirely housed in the inner cavity 3 and structured for limiting the transferable mechanical torque to a maximum mechanical torque. The pack of discs 4 comprises a plurality of first discs 5 and a plurality of second discs 6 arranged in succession along a central axis 100. Exemplarily, the first 5 and second discs 6 are alternated with each other along the central axis 100 and arranged reciprocally direct contact.

[0086] Exemplarily, the aforementioned insertion direction 101 lies on the central axis 100, one direction of the insertion direction 101 going from the insertion mouth 30 to the pack of discs 4.

[0087] The operating principle of the disc pack, based on the friction between the first and second discs, for mechanically limiting the torque transferable from the first to the second shaft (or vice versa) will not be described further as it is known per se.

[0088] Exemplarily (fig. 2) the containment body 2 comprises a cap 7 exemplarily having a substantially bell shape, and a base support 71 , with a discoidal shape. For example, the cap 7 and the base support 71 are rigidly connected to each other by a plurality of screws 73.

[0089] Exemplarily, the containment body 2, more in detail the cap 7, comprises a coupling portion 8, exemplarily with a substantially cylindrical development with respect to the central axis 100 and without through openings (e.g. it is entirely structurally contiguous).

[0090] In alternative embodiments (not shown), the coupling portion can have any polyhedra geometry and / or rotation solid geometry.

[0091] The first discs 5 are mechanically coupled to the containment body 2 at the coupling portion 8 for rigidly rotating with the containment body 2 around the central axis 100.

[0092] To this end, each first disc 5 exemplarily comprises a plurality of respective projections 51 circumferentially equally distributed with respect to the central axis 100 which protrude radially externally from the first disc 5 with respect to the central axis 100 (see for example Fig. 4).

[0093] Exemplarily, the coupling portion 8 comprises a plurality of grooves 81 (shown only partially, fig. 1 , 3 and 4) circumferentially equally distributed with respect to the central axis 100, facing the inner cavity 3. Exemplarily, each groove has a respective line of development main parallel to the central axis 100.

[0094] Exemplarily, each projection 51 of each first disc 5 engages one and only one respective groove 81 of the coupling portion 8. In detail, an inner surface (i.e. facing the inner cavity 3) of the coupling portion 8 is countershaped to a radially external profile of the first 5 discs (fig. 4).

[0095] Exemplarily, each first 5 and second disc 6 has an annular shape comprising a respective central through opening 9 (free in fig. 1 , occupied by the second shaft 91 in the remaining figures). For example, the respective central through openings 9 are coaxial to the central axis 100.

[0096] The second discs 6 are exemplary structured for mechanically coupling with the second shaft 91 when inserted into the inner cavity 3.

[0097] To this end, each second disc 6 exemplarily comprises a plurality of respective projections 61 circumferentially equally distributed with respect to the central axis 100 which protrude radially internally from the second disc 6 with respect to the central axis 100 (which will couple to the second shaft 91 , as below better described). Exemplarily, as shown in fig. 1 , the respective projections 61 of each second disc 6 are arranged along an edge of the respective central through opening 9 of the respective second disc 6. Exemplarily the first 5 discs are made of steel. Exemplarily, the second discs 6 have a stratified structure, each second disc 6 comprising a respective support disc 611 (equipped with ridges 61) made of steel, and a first and second coating layer 10 arranged on axially opposite parts of the support disc 611. Exemplarily, each first and second covering layer 10 is made of a friction material, such as for example L-504 or R-246 marketed by Inno Friction GmbH.

[0098] Exemplarily, the pack of discs 4 is subjected to a compression force parallel to the central axis 100 (for realizing the friction forces between the discs, as known).

[0099] To this end, the device 1 exemplarily comprises an adjustment system 12 structured for regulating the compression force. Exemplarily, the adjustment system 12 comprises an elastic element 13 (e.g. a disc spring or Belleville spring), operationally interposed between the containment body 2, in detail between the cap 7, and an extremal disc of the pack of discs 4 (e.g. represented by a first disc 5) is structured for keeping the pack of discs 4 in compression against the containment body 2. In detail, the pack of discs is exemplary kept in compression by the elastic element 13 against an annular abutment surface 711 realized by the first base support 71.

[0100] Exemplarily, the adjustment system 12 also comprises an adjustment element 14, structured for adjusting a degree of compression of the elastic element 13 against the extremal disc. In detail, the adjustment element 14 comprises an adjustment screw that passes through the containment body 2, at an end portion of the cap 7. Exemplarily, by varying the degree of screwing of the screw in the containment body it is possible to adjust a thrust given on the Belleville washer by one end of the adjustment screw arranged inside the containment body, in contact with the disc spring.

[0101] Exemplarily, the device comprises sealing means (not shown) at the hole made in the main body 2 and into which the screw is inserted.

[0102] Exemplarily, the containment body 2 comprises three through discharge openings 22, with a purely radial main development, (fig. 1 and 2) each having a respective inlet mouth 24 facing the inner cavity 3.

[0103] Exemplarily, the inlet mouths 24 are arranged upstream of the coupling portion 8 with respect to the insertion direction 101 , exemplarily between them angularly equally distributed around the central axis 100 (with an angle of approximately 120° between them).

[0104] More in detail, in the examples shown, each discharge opening 22 is made by a respective groove made on an end face (not visible, exemplarily having development on a plane orthogonal to the central axis 100) of the containment body 2. Exemplarily the end face represents the face of the containment body at which the insertion mouth 30 is made.

[0105] Exemplarily, each groove develops from the insertion mouth 30 to an external surface of the containment body 2, with the inlet mouths 24 contiguous to the insertion mouth 30.

[0106] Exemplarily, the containment body 2 is sealed with the exception of the insertion mouth 30 and the inlet mouths 24. In particular, the inner cavity 3 is exemplarily axially blind (e.g. with reference to the central axis 100). In other words, the containment body 2 exemplarily comprises a back wall (axially opposite to the insertion mouth 30) which contributes to delimiting the inner cavity 3. The back wall coincides exemplarily with an end portion of the cap 7, where it is arranged the aforementioned adjustment system 12. For example, the back wall is devoid of through openings of sufficient size to allow their passage by the second shaft 91 when inserted into the inner cavity 3.

[0107] According to another aspect, the present invention concerns a system for transmitting motion 99 from the first shaft 90 to the second shaft 91 (or vice versa).

[0108] Exemplarily, the transmission system 99 is shown schematically in its main components in figure 5.

[0109] Exemplarily, the transmission system 99 comprises the first shaft 90, to which the containment body 2 is rigidly fixed for rigidly rotating with the first shaft around an axis of the first shaft 90 (not shown). For example, the axis of the first tree coincides with the central axis 100.

[0110] Exemplarily, the device 1 is fixed to the first shaft with the insertion mouth 30 facing the first shaft 90. Exemplarily, the end face of the containment body 2 is in direct contact with the first shaft 90, and the first shaft 90 is suitably shaped to leave free access to the insertion mouth 30 to allow the positioning of the second shaft 91 . To this end, the first shaft 90 coincides exemplarily with a gear wheel 902 exemplarily having a respective central through opening 903, exemplarily centered in the axis of the first shaft (i.e. the rotation axis of the wheel). Exemplarily, the insertion mouth 30 is arranged at an edge of the central passing opening 903, making the inner cavity 3 communicating (and contiguous) with the central passing opening 903 of the gear wheel 902.

[0111] More in detail, the containment body 2 is exemplarily fixed directly to a lateral face of the gear wheel 902, for example to an attachment flange 72 of the gear wheel 902 (the attachment flange 72 is exemplarily shown in all figures 1-5). Exemplarily, the attachment flange 72 forms at least part of the aforementioned lateral face of the gear wheel 902. Exemplarily, the attachment flange is made integral, e.g. by welding, riveting, to the rest of the gear wheel 902.

[0112] Exemplarily, the containment body is fixed to the gear wheel 902 (more precisely to the attachment flange 72) through some of the aforementioned screws 73. As in fact exemplarily shown (fig. 2-5), some of the screws 73 mutually fix the cap 7, the first base support 71 and the attachment flange 72.

[0113] Exemplarily, the system 99 also comprises the second shaft 91 , inserted into the inner cavity 3 of the device 1 via the insertion mouth 30, in the respective central through openings 9 of the first 5 and second discs 6, and mechanically coupled to the second discs 6. Exemplarily therefore the second shaft 91 extends through the gear wheel 902 in correspondence with the central through opening 903.

[0114] In order to couple with the second discs, the second shaft 91 exemplarily comprises a plurality of respective grooves 911 circumferentially equally distributed with respect to an axis of the second shaft 91 (not shown, exemplarily coinciding with the central axis 100) made on an external surface of the second shaft 91 ( see in particular fig. 3).

[0115] Exemplarily, each groove 911 of the second shaft 91 has a respective main development line parallel to the axis of the second shaft, i.e. in use parallel to the central axis 100 (to allow the insertion). Exemplarily, the grooves 911 of the second shaft 91 are made at an end portion of the second shaft, exemplarily entirely housed in the inner cavity 3.

[0116] Exemplarily, the projections 61 of each second disc 6 each engage one and only one respective groove 911 of the second shaft 91 . Exemplarily, the external surface of the second shaft at the end portion is substantially counter-shaped to a radially inner profile of the second discs 6.

[0117] Exemplarily, the system 99 further comprises a main body 98 having a housing cavity 94 open at a housing mouth 96 (exemplarily reversibly closed by a removable cover, not shown).

[0118] Exemplarily, the gear wheel 902 is entirely housed in the housing cavity 94. Exemplarily, the second shaft 91 is partially housed in the housing cavity 94.

[0119] Exemplarily, the system 99 comprises a separation partition 40 which separates the housing cavity 94 into a first 97 and a second sub-cavity 95. Exemplary, the septum 40 comprises a communication mouth 905 between the first 97 and the second subcavity 95.

[0120] Exemplarily, the first shaft 90 (in particular the attachment flange 72) is at least partially arranged at the communication mouth 905, occluding (tightly) the communication mouth 905.

[0121] Exemplarily, the transmission system comprises a respective gasket 16 fixed to the septum 40 at the communication mouth 905, the respective gasket 16 being placed in contact between the first shaft 90 (in particular the attachment flange 72) and the septum 40. Exemplarily the attachment flange 72 rotates in sliding motion on the gasket 16. Exemplarily, the communication mouth 905 has cylindrical symmetry around the central axis 100 (and the axis of the gear wheel).

[0122] Exemplarily, the limiting device 1 is entirely housed in the first sub-cavity 97, the first sub-cavity 97 being exemplary devoid of lubricating agents (containing air).

[0123] Exemplarily, the system 99 comprises a worm screw 901 mechanically meshed with the gear wheel at a portion of the gear wheel 902 housed in the second sub-cavity 95.

[0124] Exemplarily, the second sub-cavity 95 is filled with a lubricating agent in order to lubricate the mechanical coupling between the gear wheel and the worm screw. Thanks to the septum and the attachment portion of the gear wheel, the lubricating agent is confined only to the second sub-cavity 95. Given the structure of the system 99 described so far, it follows that, exemplarily, the lubricating agent can come into contact with the device 1 (for example with an edge of the insertion mouth 30) substantially only through the central passing opening 903 of the gear wheel 902 (fig. 5).

[0125] Exemplarily, the transmission system 99 comprises a respective further gasket 15 fixed to the gear wheel 902 at the central through opening 903 of the gear wheel 902 and placed in contact between the gear wheel 902 (more precisely between the attachment flange 72) and the second shaft 91. This respective further gasket 15 exemplarily contributes to separating the inner cavity 3 of the device from the second sub-cavity 95.

[0126] In one embodiment (not shown), in addition or as an alternative to the gasket 15, the device 1 can comprise a respective gasket (not shown) fixed to the containment body 2 and suitably shaped to be placed, in contact with the seal, between the containment body 2 and the second shaft 91 (inserted into the inner cavity 3). In this embodiment the respective gasket of the device 1 is advantageously arranged in an intermediate position between the insertion mouth 30 and the pack of discs 4 and the inlet mouths 24 are advantageously arranged upstream of the gasket of the device 1 with reference to the direction of insertion 101 .

[0127] In the embodiment in which the device 1 comprises the aforementioned gasket, part of the containment body (comprising the coupling portion 8 and the back wall of the cap 7), the gasket and the second shaft 91 form exemplarily, at the inner cavity 3 and with the second shaft 91 inserted therein, a sealed chamber which entirely encloses the pack of discs 4, advantageously devoid of lubricating agents inside it. In the embodiment which comprises both the aforementioned gaskets, an antechamber is realized between the gasket 15 and the device gasket (which precedes the aforementioned sealed chamber with respect to the insertion direction 101) at which the inlet ports 24 are arranged In this way the gasket of the device 1 further slows down any lubricating agents that may have leaked into the antechamber (e.g. through the respective further gasket 15), facilitating their discharge through the discharge openings 22.

[0128] For example, each of the aforementioned gaskets can be made of elastically flexible polymeric material, for example a gasket of a type known as a BAUMSL 042X062X8 gasket marketed by FREUDENBERG.

Claims

CLAIMS1 . Mechanical torque limiting device (1) for limiting a mechanical torque transferable from a first shaft (90) to a second shaft (91) or vice versa, said device (1) comprising:- a containment body (2) structured to be interposed between said first shaft (90) and said second shaft (91) for mechanically connecting to each other said first (90) and second shaft (91), said containment body (2) comprising an inner cavity (3) open at an insertion mouth (30);- a pack of discs (4) entirely housed in said inner cavity (3) and structured for limiting said transferable mechanical torque to a maximum mechanical torque, the pack of discs (4) comprising a plurality of first discs (5) and a plurality of second discs (6) arranged in succession along a central axis (100), wherein said containment body (2) comprises a coupling portion (8), said first discs (5) being mechanically coupled to said containment body (2) at said coupling portion (8) for rigidly rotating with said containment body (2) about said central axis (100), wherein said inner cavity (3) is conformed to allow an insertion of said second shaft (91 ) into said inner cavity (3) through said insertion mouth (30) along an insertion direction (101), said second discs (6) being structured for mechanically coupling with said second shaft (91) when inserted into said inner cavity (3), wherein said containment body (2) comprises one or more through discharge openings (22), wherein each through discharge opening (22) comprises a respective inlet mouth (24) facing said inner cavity (3), and wherein each respective inlet mouth (24) is arranged upstream of said coupling portion (8).

2. Device (1) according to claim 1 , wherein each respective inlet mouth (24) is arranged externally to said coupling portion (8), wherein each respective inlet mouth (24) is angularly equally distributed about said central axis (100) with respect to remaining inlet mouths (24), wherein said containment body (2) comprises an end face, said insertion mouth (30) being made at said end face, wherein one or more of said one or more through discharge openings (22) comprises a respective groove made onto said end face, wherein each groove develops from said insertion mouth (30) to an external surface of said containment body (2), and wherein each through discharge opening (22) has a respective main development having at least one radial component with respect to said central axis (100).

3. Device (1) according to any one of the previous claims, wherein said containment body (2) is sealed with the exception of said insertion mouth (30) and of said inlet mouths (24), wherein said coupling portion (8) has respective main development substantially cylindrical about said central axis (100), wherein each first disc (5) comprises one or more respective projections (51) which protrude radially externally from the first disc (5) with respect to said central axis (100), and said coupling portion (8) comprises one or more respective grooves (81) facing said inner cavity (3), each groove (81) of said coupling portion (8) having a respective main development line substantially parallel to said central axis (100), and wherein said one or more projections (51) of each first disc (5) each engage a respective groove (81) of said one or more grooves ofsaid coupling portion (8).

4. Device (1) according to any one of the previous claims, wherein each first (5) and second disc (6) has annular shape comprising a respective central through opening (9), said respective central through openings(9) being coaxial to said central axis (100), and wherein each second disc (6) comprises one or more respective projections (61) which protrude radially internally from the second disc (6) with respect to said central axis (100), wherein said first (5) and second discs (6) are alternated to each other along the central axis (100) and arranged in direct contact with each other, wherein said first discs (5) are made of steel, wherein each second disc (6) comprises a support disc (611) and a first and a second coating layer (10) arranged at axially opposite parts of said support disc (611), and wherein said first and second coating layer(10) are made of a friction material.

5. Device (1 ) according to any one of the previous claims, comprising an adjustment system (12) structured for adjusting a compressive force acting on said pack of discs (4), and wherein said adjustment system (12) comprises an elastic element (13), operatively interposed between said containment body (2) and an extremal disc of said pack of discs (4), and an adjustment element (14), structured for adjusting a degree of compression of said elastic element (13) against said extremal disc.

6. Device (1) according to any one of the previous claims, comprising a gasket fixed to said containment body (2) and structured for being interposed between said containment body (2) and said second shaft (91) when inserted into said inner cavity (3), and wherein said gasket is arranged in an intermediate position between said coupling portion (8) and said inlet mouths (24).

7. System for motion transmission (99) comprising:- a mechanical torque limiting device (1) according to any one of claims from 1 to 6;- said first shaft (90), said containment body being rigidly fixed to said first shaft (90);- said second shaft (91) inserted into said inner cavity (3) and mechanically coupled to said second discs (6) for rigidly rotating together with said second discs (6) about said central axis (100);- a main body (98) having a housing cavity (94), wherein said main body (98) comprises a separation septum (40) which separates said housing cavity (94) into a first (97) and a second sub-cavity (95), wherein said separation septum (40) comprises a communication mouth (905) between said first (97) and second sub-cavity (95), wherein said first shaft (90) is at least partially arranged at said communication mouth (905) closing off said communication mouth (905), wherein said limiting device (1) is entirely housed in said first sub-cavity (97), and wherein said first subcavity (97) is devoid of lubricating agents.

8. System (99) according to claim 7, comprising a respective gasket (16) fixed to said separating septum (40) at said communication mouth (905), wherein said respective gasket (16) is interposed in contact between said first shaft (90) and said separation septum (40).

9. System (99) according to claim 7 or 8, wherein said containment body (2) is fixed to said first shaft (90) for rigidly rotating with said first shaft around an axis of said first shaft coinciding with said central axis (100), wherein said first shaft (90) is a gear wheel (902), wherein said gear wheel (902) comprises a respective central through opening (903), wherein said insertion mouth (30) is arranged in communication with said central through opening (903) of the gear wheel (902), wherein said system (99) comprises a respective further gasket (15) fixed to said first shaft (90) at said central through opening (903) of said first shaft (90), and wherein said respective further gasket (15) is interposed in contact between said first shaft (90) and said second shaft (91).

10. System (99) according to any one of the claims from 7 to 9, wherein said second shaft (91) comprises one or more respective grooves (911) made on an external surface of said second shaft (91), wherein each groove (911) of said second shaft (91) has a respective main development line substantially parallel to an axis of said second shaft, wherein said second shaft (91) is inserted into respective central through openings (9) of said first (5) and second discs (6), wherein one or more projections (61) of each second disc each engage a respective groove (911) of said second shaft (91), wherein said axis of said second shaft (91) coincides with said central axis (100), wherein said housing cavity (94) is open at a housing mouth (96), and wherein said mechanical torque limiting device (1) is reversibly rigidly fixable to said first shaft (90) through said housing mouth (96) of said main body (98).

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