Centrifugal clutch assembly, especially for motorcycles.

Abstract

To provide a centrifugal clutch that has well-set operation and provides pleasant use for a user.SOLUTION: A clutch is provided which has: a fixed hub (101); a movable hub (102); and a plurality of plates (103) interposed to selectively transmit a torque. A centrifugal pressure plate assembly (200) includes: a mass carrier (201); and a plurality of radially movable mass elements (202). Each mass element (202) includes a pivot (203) and is configured to exert axial thrust on a thrust surface (204) of the centrifugal pressure plate assembly (200), to bring the movable hub (102) closer to the fixed hub (103) and to increase the variable axial load. Each mass element (202) includes at least one respective rolling element in contact with the thrust surface (204). The thrust surface (204) has a profile that is sloped and raised towards the external position.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a clutch, particularly a clutch for a two-wheeled vehicle.

[0002] Generally, the present invention relates to a clutch including a fixed hub and a movable hub, and a plurality of clutch plates are inserted between the fixed hub and the movable hub, which are capable of transmitting torque when axially pushed toward each other. The clutch includes a centrifugal assembly adapted to axially push the fixed hub and the movable hub closer according to the rotational speed of the clutch.

Background Art

[0003] The document EP2400177(A1) of Adler Societa per Azioni mentions a clutch equipped with an automatic engagement device and simultaneously a manual operation device. The clutch includes a centrifugal assembly, where a rotatably connected mass is displaced under the centrifugal effect and cooperates with a pressure ring to cause axial compression of the plate pack in order to achieve the connection condition of the clutch.

[0004] The document GB995989(A) mentions a clutch operated by a centrifugal mechanism with centrifugal weights acting on a pressure plate.

[0005] The document WO2019 / ... / 101342(A1) of Adler Societa per Azioni mentions a clutch provided with a centrifugal assembly including a plurality of mass elements arranged radially within a mass holder, where each mass element includes a body and a columnar element connected to a pivot point.

[0006] Reference EP2175154(A2) describes a centrifugal multi-plate friction clutch comprising a centrifugal weight configured to receive centrifugal force by rotating with the clutch housing and move away from the axis of the clutch shaft, and a cam mechanism configured to convert the centrifugal force into an axial force by contacting the centrifugal weight.

[0007] Reference JP2012241804(A) describes a multi-plate automatic centrifugal clutch device that includes centrifugal rollers that press the drive plate and the driven plate together by friction using the effect of centrifugal force generated by the rotation of the driven shaft.

[0008] Reference DE1087460(B) refers to a centrifugal clutch, particularly for automobiles, which has rolling elements as centrifugal weights, wherein each centrifugal weight consists of several rotatably interconnected roller-like rolling elements of different diameters, and the centrifugal weights are movably arranged between two mutually inclined control surfaces.

[0009] The prior art solution enables automatic engagement and disengagement of centrifugal clutches.

[0010] However, prior art centrifugal clutches can be perfected in terms of smooth operation, particularly to improve riding comfort in motorcycles.

[0011] In particular, the solutions of prior art can be perfected in terms of smoothness of engagement over a wider range of rotational speeds. Torque transmission, especially in automatic centrifugal clutches for motorcycles, can also be further optimized.

[0012] For example, the behavior of a centrifugal clutch while engaged provides a different driving feel than the behavior of the same centrifugal clutch when disengaged, which can worsen the user's driving experience. These differences in behavior can worsen as the clutch plates wear down.

[0013] Generally, known centrifugal clutches have friction issues, resulting in hysteresis in their operation, including the action of the centrifugal pressure plate assembly on the hub. The hysteresis problem means that the torque transmitted by the clutch is not always linear, as it depends not only on the number of rpm but also on the driving conditions. In particular, at the same speed, a centrifugal clutch may tend to slip when accelerating or with the throttle open and tend to block when decelerating or closing the throttle. [Overview of the project]

[0014] The objective of the present invention is to solve specific problems of the prior art.

[0015] One particular object of the present invention is to provide a centrifugal clutch that has well-defined operation and provides a comfortable user experience.

[0016] A further specific object of the present invention is to make the centrifugal clutch perfect in terms of smoothness of engagement and disengagement, preferably over a wider range of rotational speeds.

[0017] A further specific object of the present invention is to provide a clutch that optimizes torque transmission during transitions from low rotational speed to high rotational speed, and even during the reverse transition from high rotational speed to low rotational speed.

[0018] A further specific object of the present invention is to alleviate the friction problem in centrifugal clutches and the resulting operational hysteresis.

[0019] A further specific objective is to provide an improved centrifugal clutch that allows for both automatic and manual operation, particularly for effective use in motorcycles.

[0020] Another specific object of the present invention is to provide a clutch that provides reliable operation.

[0021] A further specific object of the present invention is to provide a compact clutch for effective use, particularly in motorcycles.

[0022] A further specific object of the present invention is to provide a clutch that improves operation in engine braking situations.

[0023] These and other objectives are achieved by the clutch and associated transmission system, as specified in the attached claims, which form an integral part of this description.

[0024] The solution behind the present invention is to provide a centrifugal clutch comprising a centrifugal pressure plate assembly that can at least partially control the variable axial load applied to the clutch plates.

[0025] The centrifugal pressure plate assembly comprises a mass carrier configured to rotate with a clutch, and a plurality of radially movable mass elements within the centrifugal pressure plate assembly, where each mass element is provided with a pivot connected to the mass carrier and is therefore configured to be displaced to an external position under centrifugal effect.

[0026] Due to this displacement under centrifugal effect, the mass element is further configured to apply axial thrust to the thrust surface of the centrifugal pressure plate assembly, bringing the movable hub closer to the fixed hub and increasing the variable axial load.

[0027] Each mass element has at least one rolling element in contact with the thrust surface. An advantage is that the presence of the rolling elements reduces sliding friction between the mass element and the thrust surface. Thus, the hysteresis effect decreases as engine speed changes, particularly during starting, improving the operation with respect to transmitted torque and enhancing the clutch's adjustability.

[0028] The thrust surface has an outer shape that slopes and rises towards the external position. Preferably, this outer shape may include a curved portion. As an advantage, the sloped outer shape enables the rotational angular velocity of the clutch to be stably correlated with the axial load, enables better control of torque transmission by the clutch, and particularly enables the first engagement of the clutch that is not abrupt during startup.

[0029] Overall, the centrifugal clutch of the present invention enables smoother and more comfortable operation for the user.

[0030] In particular, the centrifugal clutch of the present invention optimizes torque transmission during the transition from low rotational speed to high rotational speed and vice versa, during the transition from high rotational speed to low rotational speed.

[0031] Preferably, the centrifugal clutch has a fixed hub provided with a first sliding element and a movable hub provided with a second sliding element, which are configured to engage with each other and slide relative to each other when receiving the torque acting on the clutch so as to at least partially change the variable axial load.

[0032] In this way, as an advantage, it is possible to achieve a further closing effect of the plate pack and increase the torque that can be transmitted by the clutch in either a state of rapid acceleration or engine braking. As an advantage, the centrifugal clutch according to the present invention improves the increase in the torque that can be transmitted by the clutch under acceleration conditions when the centrifugal pressure plate assembly tends to open the clutch plate, while at the same time preventing undesirable losses of engine braking in a braking or decelerating state.

[0033] Generally, the fully set operation of the centrifugal clutch according to the present invention is particularly advantageous for applications in motorcycles, particularly high-performance motorcycles, enabling an excellent riding comfort.

[0034] Further features and advantages will become apparent from the following detailed description of preferred non-limiting embodiments of the invention and from the dependent claims outlining preferred and particularly advantageous embodiments of the invention.

[0035] The present invention is illustrated with reference to the following figures, which are provided as examples without limitation. [Brief explanation of the drawing]

[0036] [Figure 1] This shows a cross-sectional view of an embodiment of the clutch according to the present invention. [Figure 2] This shows a three-dimensional diagram of an embodiment of a mass element for a clutch according to the present invention. [Figure 3] This shows an enlarged cross-sectional view of the clutch centrifugal pressure plate assembly according to the present invention. [Figure 4] This shows a first cross-section of the centrifugal pressure plate assembly in a first closed configuration. [Figure 5] Figure 4 shows a second cross-section of the centrifugal pressure plate assembly in the first closed configuration. [Figure 6] This shows the first cross-section of the centrifugal pressure plate assembly in the second intermediate configuration. [Figure 7] Figure 6 shows a second cross-section of the centrifugal pressure plate assembly in the second intermediate configuration. [Figure 8] The first cross-section of the centrifugal pressure plate assembly in a third open configuration is shown. [Figure 9] Figure 8 shows a second cross-section of the centrifugal pressure plate assembly in a third open configuration. [Figure 10] This shows a partial three-dimensional view of a subassembly of a clutch hub assembly according to the present invention. [Figure 11] This shows a three-dimensional view of the fixed hub and movable hub of the clutch according to the present invention. [Figure 12] A cross-sectional view of a further embodiment of the clutch according to the present invention is shown. [Figure 13]This shows a three-dimensional diagram of an embodiment of the overstroke spring according to the present invention.

[0037] Similar elements are shown in different drawings using the same reference number. If several elements of the same type are shown in the same drawing, only one or some of them are explicitly indicated by their respective reference numbers, while the others are assumed to be included by analogy. [Modes for carrying out the invention]

[0038] Figure 1 shows a cross-sectional view of an embodiment of the clutch 100 according to the present invention.

[0039] In this embodiment, the clutch 100 is used to control the engagement of rotational motion between a drive shaft and a primary gear, which are joined to the clutch housing of a vehicle, particularly a motorcycle.

[0040] The clutch 100 includes a fixed hub 101 specially configured to connect to the rotating shaft 10 of the vehicle to which the clutch is mounted. The fixed hub 101 is preferably mounted to the primary shaft 10 of the gearbox.

[0041] At that time, the clutch 100 includes a movable hub 102 configured to be mounted axially on a fixed hub 101.

[0042] The clutch 100 comprises multiple plates 103 inserted between the fixed hub 101 and the movable hub 102. In this sense, the clutch 100 is a "multi-plate clutch" type.

[0043] In this embodiment, the plate 103 includes a plurality of clutch plates or drive plates, particularly coated plates, which include protruding elements configured to connect with the clutch housing 11, which in turn is preferably connected to the drive shaft of the vehicle. The plate 103 also includes a plurality of driven plates, which include internal teeth configured to connect with the movable hub 102, and are arranged alternately with respect to the drive plates.

[0044] Generally, the clutch housing has a housing 11 outside a fixed hub 101 that rotates around a rotation axis. The fixed hub 101 is configured to connect to a shaft 10 that is coaxial with the rotation axis. The movable hub 102 is axially mounted to the fixed hub 101 along the rotation axis.

[0045] Preferably, the clutch 100 also includes an annular judder spring 104 positioned on the first of the multiple plates 103 and near the flange on the movable hub 102. In one modification, the judder spring 104 may be replaced with a double spring system in which each has half the stroke compared to the judder spring 104, thereby improving the smoothness of the initial engagement of the clutch.

[0046] The fixed hub 101 and the movable hub 102 are shaped to rotate together when mounted axially, and therefore the fixed hub 101 and the movable hub 102 are adapted to receive torque.

[0047] Furthermore, the fixed hub 101 and the movable hub 102 are shaped to slide axially, moving away from or closer to each other, in a manner that reduces or increases the strength of the axial load on the plate 103.

[0048] In this way, the fixed hub 101 and the movable hub 102 apply a variable axial load to the plate 103, thereby allowing torque to be transmitted between the housing and the engine's rotating shaft by the clutch 100 when the plate 103 is compressed together by the axial load, while the clutch disengages with virtually no torque transmitted when the axial load decreases and the plate 103 slides freely over each other, as the fixed hub 101 and the movable hub 102 are positioned sufficiently far apart.

[0049] In this way, the clutch 100 can selectively transmit torque between the two rotating shafts according to external control. This external control may be manually operated, via a lever or pedal, or implemented by a servo mechanism.

[0050] Furthermore, the clutch 100 includes a centrifugal pressure plate assembly 200 for at least partially controlling the variable axial load acting on the plate 103.

[0051] The centrifugal pressure plate assembly 200 includes a mass carrier 201 configured to rotate together with the clutch 100.

[0052] The centrifugal pressure plate assembly 200 further comprises a plurality of mass elements 202 that are radially movable within the centrifugal pressure plate assembly 200. Each mass element 202 is provided with a pivot 203 connected to a mass carrier 201, which allows the mass element 202 to be displaced to an external position under centrifugal effect.

[0053] Due to the displacement under centrifugal effect, the mass element 202 is further configured to apply axial thrust to the thrust surface 204 of the centrifugal pressure plate assembly 200, bringing the movable hub 102 closer to the fixed hub 101 and increasing the variable axial load acting on the plate 103.

[0054] Therefore, clutch 100 is defined as a centrifugal clutch, which means that clutch 100 includes automatic operation by the centrifugal pressure plate assembly 200, but at the same time, manual operation during gear changes is possible.

[0055] In general, it should be understood that the clutch based on the present invention may be of either a wet clutch or a dry clutch type.

[0056] Figure 2 shows a three-dimensional view of an embodiment of the mass element 202 of the clutch according to the present invention.

[0057] Each mass element 202 in the clutch 100 comprises at least one rolling element 205 configured to contact the thrust surface 204.

[0058] In this embodiment, there is a pair of roller-type rolling elements 205 pivoted on each axis of the mass element 202. Different versions of the rolling elements 205 may be provided, for example, with additional roller bearings or pivoted directly on the mass element. A version with only one rolling element 205 may also be conceivable.

[0059] As can be seen, the mass element 202 comprises a body 206 with rolling elements 205, and further comprises a substantially elongated column element 207 that connects the pivot 203 to the body 206.

[0060] The column element 207 is configured to increase the lever arm, which is beneficial for the displacement of the mass element 202 in the centrifugal pressure plate assembly 200 under centrifugal effect.

[0061] Figure 3 shows an enlarged cross-sectional view of the centrifugal pressure plate assembly 200 according to the present invention. In this cross-sectional view, one of the rolling elements 205 is visible, but the pivot 203 is not, as it is actually located in a different cross-section.

[0062] As explained, under centrifugal force, the displacement causes the mass element 202 to apply axial thrust to the thrust surface 204 of the centrifugal pressure plate assembly 200. In this way, the centrifugal effect can be used to bring the movable hub 102 closer to the fixed hub 101 and increase the variable axial load acting on the plate 103.

[0063] The thrust surface 204 has an outer shape that slopes upward toward the outermost position assumed by the mass element 202 in the centrifugal pressure plate assembly 200.

[0064] The inclined and rising outer shape allows the axial load acting on the plate to gradually increase as the mass element 202 opens, and this acts on the thrust surface via the interaction of the rolling element 205.

[0065] Generally, the inclined shape of the thrust surface 204 allows the rotational angular velocity of the clutch to be correlated with the axial load, because the centrifugal action on the mass element 202 depends on the angular velocity, and these elements, which are open in the centrifugal pressure plate assembly 200, provide a load that gradually increases and contributes to the closing of the fixed hub 101 and movable hub 102 acting on the plate 103.

[0066] Preferably, the inclined outer shape includes a curved portion 301 having a slope that increases toward the outermost position assumed by the mass element 202 in the centrifugal pressure plate assembly 200. In other words, the curved portion 301 appears to have a concave surface into which the rolling element 205 engages.

[0067] This curved section 301 is configured such that the thrust angle of the rolling element 205 on the thrust surface 204 increases when the mass element 202 opens due to the centrifugal effect. This helps to improve the gradual progression of the axial load acting on the plate 103, which is established during the centrifugal release of the mass element 202.

[0068] As illustrated with reference to the following diagram, the operation and effect of the curved section 301 become more apparent when considering different operating configurations of the centrifugal pressure plate assembly 200.

[0069] Figure 4 shows a first cross-section of the centrifugal pressure plate assembly 200, with the rolling element 205 visible in a first closed configuration where the mass element is in its innermost position. This first closed configuration corresponds to operating conditions in which the clutch 100 is substantially disengaged, particularly for an engine rotating at idle speed, where no axial load acts on the plate 103.

[0070] In the first closed configuration, the curved portion 301 defines a first pressure angle 401, which is defined between the axial direction of the variable axial load acting on the plate 103 and the direction of the load transmitted between the rolling element 205 and the thrust surface 204, the latter direction being perpendicular to the tangent to the thrust surface 204 at the contact point, and the contact point being substantially internal.

[0071] Figure 5 shows a second cross-section of the centrifugal pressure plate assembly of Figure 4, where the body 206 and column element 207 of the mass element 202 are still visible in the first closed configuration.

[0072] In this figure, it can be understood that the mass element 202 has its center of mass within the body 206, and the column element 207 defines a pivot 203 that is radially outward from the center of mass with respect to the axial direction of the rotation axis on the clutch 100. This helps to increase the centrifugal effect and thrust provided by the mass element 202.

[0073] Figure 6 shows a first cross-section of the centrifugal pressure plate assembly 200 corresponding to Figure 4 in a second intermediate configuration in which the mass element begins to undergo radial displacement. This second intermediate configuration typically corresponds to a standing start situation, particularly for engine speeds from just above idle speed to medium speed, where the clutch 100 begins to engage, generating a moderate axial load acting on the plate 103.

[0074] In the second intermediate configuration, the curved portion 301 defines a second pressure angle 402, which is still defined between the axial direction of the variable axial load acting on the plate 103 and the direction of the load transmitted between the rolling element 205 and the thrust surface 204, the latter direction being perpendicular to the tangent to the thrust surface 204 at the contact point, and the contact point being further outward.

[0075] The second pressure angle 402 in the second intermediate configuration is greater than the first pressure angle 401 in the first closed configuration.

[0076] Figure 7 shows a second cross-section of the centrifugal pressure plate assembly 200 in the second intermediate configuration described earlier, corresponding to Figure 5.

[0077] Figure 8 shows a first cross-section of the centrifugal pressure plate assembly 200, corresponding to Figures 4 and 6, in a third open configuration in which the mass elements have fully completed radial displacement. This third open configuration corresponds to operating conditions that typically correspond to driving and / or acceleration situations, particularly from medium to high engine speeds, in which the clutch 100 is fully engaged and provides an axial load acting on the plate 103 that fully transmits the torque acting on the clutch.

[0078] In the third open configuration, the curved portion 301 defines a third pressure angle 403, which is also defined between the axial direction of the variable axial load acting on the plate 103 and the direction of the load transmitted between the rolling element 205 and the thrust surface 204, the latter direction being perpendicular to the tangent to the thrust surface 204 at the contact point, and the contact point being further outward.

[0079] The third pressure angle 403 in the third open configuration is greater than the first pressure angle 401 in the first closed configuration and the second pressure angle 402 in the second intermediate configuration.

[0080] Figure 9 shows a second cross-section of the centrifugal pressure plate assembly 200 in the third open configuration described above, corresponding to Figures 5 and 7.

[0081] In this third open configuration, the centrifugal pressure plate assembly 200 has substantially completed its centrifugal opening.

[0082] In particular, the mass carrier 201 is configured to limit the radial displacement of the mass element 202 to achieve the maximum open configuration at a given rotational speed of the clutch 100. Specifically, the mass carrier 201 includes a contact portion located outside the mass element that acts as a limiter on the radial displacement of the mass element 202. More specifically, in a preferred embodiment, the contact portion is configured to stop the radial displacement by interacting with each portion of the column element 207 of the mass element 202. Alternatively, the contact portion may be configured to interact with different portions of the mass element to limit its final position of radial displacement.

[0083] By considering the above drawings, it can be seen that the curved portion 301 defines several pressure angles, for example, 401, 402, and 403, which are pressure angles defined between the direction of the generally variable axial load and the direction of the load transmitted between the rolling element 205 and the thrust surface 204.

[0084] These pressure angles 401, 402, and 403 change and increase as they move toward the external position. In other words, the curved section 301 has a gradient that increases toward the outermost position assumed by the mass element 202 within the centrifugal pressure plate assembly 200, thereby increasing the pressure angle that affects the axial and radial distribution of the load generated by the mass element 202.

[0085] In general, it can be said that the curved portion 301 is therefore configured to provide a stable correlation between the rotational speed of the clutch 100 and the variable axial load acting on the plate 103.

[0086] Figure 10 shows a three-dimensional view of the fixed hub 101, the movable hub 102, and the intervening plate 103, some of which have been removed from the drawing to allow a view of the inside of the clutch 100.

[0087] The fixed hub 101 includes a first sliding element 501, and the movable hub 102 includes a second sliding element 502. The first sliding element 501 and the second sliding element 502 are configured to engage with each other and slide relative to each other when subjected to torque acting on the clutch 100 in order to at least partially change the variable axial load acting on the plate 103.

[0088] Figure 11 shows a three-dimensional view of the fixed hub 101 and the movable hub 102 separated from each other, further illustrating the operation of the first sliding element 501 and the second sliding element 502.

[0089] The first sliding element 501 and the second sliding element 502 each include a first sliding surface 510 for traction torque, which is inclined according to a first helix and configured to mesh with each other when the fixed hub 101 is subjected to traction torque, thereby increasing the variable axial load on the plate 103 by sliding the first sliding element 501 on the second sliding element 502 and bringing the movable hub 102 closer to the fixed hub 101.

[0090] The first sliding element 501 and the second sliding element 502 further include a second sliding surface 520 for reverse torque, which is tilted according to a second helix of opposite rotation to a first helix, and is configured to mesh with each other when the fixed hub 101 is subjected to a reverse torque, i.e., a torque opposite to the traction torque, in order to increase the variable axial load acting on the plate 103 by sliding the first sliding element 501 on the second sliding element 502, thereby bringing the movable hub 102 closer to the fixed hub 101.

[0091] As an advantage, it should be noted that the effect of the sliding elements 501 and 502 on the axial load acting on the plate 103 is combined synergistically with the effect of the centrifugal pressure plate assembly 200 described above.

[0092] Since the first inclined helix of the first sliding surface 510 for traction torque is in the opposite direction to the second inclined helix of the second sliding surface 520 for reverse torque, the sliding surfaces are inclined at two opposite angles with respect to the reference axis direction of the clutch 100's shaft.

[0093] The movable hub 102 further comprises a crown-shaped extension element 530, and the multiple plates 103 are assembled around the extension element 530. In particular, the extension element 530 has an outer surface shaped to connect with the driven plates, preferably the internal teeth on all of the driven plates, among the multiple plates 103. Specifically, the extension element 530 has multiple grooves parallel to each other in the axial direction. By housing all the driven plates on the extension element 530, greater adjustability and more effective torque transmission of the clutch 100 are obtained. In fact, the precaution of housing all the driven plates within the crown-shaped extension element 530 allows for operation by the sliding surfaces 510 or 520 at a higher helical pitch during engagement, resulting in the advantage of better adjustability of the clutch 100.

[0094] Preferably, the second sliding element 502 of the movable hub 102 is adjacent to the inner surface of the extension element 503, and preferably, the second sliding element 502 is a substantially triangular or substantially trapezoidal convex portion.

[0095] The advantages include better lubrication of the components inside the clutch, improved cooling, and reduced wear.

[0096] The first sliding element 501 of the fixed hub is a recess with an opening at the top, through which the second sliding element 502 passes when the movable hub 102 is assembled on the fixed hub 101, and preferably the first sliding element 501 is a recess that is approximately triangular or trapezoidal.

[0097] As described, the first sliding surface 510 is inclined according to a first angle with respect to the axial direction of the clutch 100, and the second sliding surface 520 is inclined according to a second angle with respect to its axial direction, the second angle having an inclination opposite to that of the first angle.

[0098] Therefore, the first sliding surface 510 and the second sliding surface 520 are configured to provide engine braking when the fixed hub 101 is subjected to a reverse torque that may be generated by the vehicle's wheel, and to increase the engine braking torque that can be absorbed by the vehicle's engine by increasing the axial load acting on the plate 103.

[0099] This "engine braking" is a condition in which the vehicle is slowed down by using a delayed drag force within the engine, rather than using an external braking mechanism such as a disc, drum, or similar brake system. Engine braking occurs particularly in gasoline engines, especially four-stroke engines, when the throttle is released while the gears and clutch are engaged.

[0100] As an advantage, the second sliding surface 520 is configured to generate an axial load under "motoring" conditions, particularly under engine braking conditions, enabling the use of engine braking, especially downhill and during cruising, when high gear ratios are used at low engine speeds.

[0101] Thanks to the first sliding surface 510, by acceleration, i.e., by providing traction torque to the clutch, the movable hub 102 and the fixed hub 101 tend to "move closer" to each other, increasing the axial load acting on the plate pack 103 which is added to the axial load generated by the centrifugal pressure plate assembly 200 described above.

[0102] In this way, a greater torque can be transmitted through the clutch 100 under the vehicle's acceleration condition.

[0103] Even while released, i.e., while providing reverse torque to the clutch 100, the movable hub 102 and the fixed hub 101 again tend to "move closer" to each other under engine braking conditions, increasing the axial load acting on the plate pack 103. At this time, the second sliding surface 520 is such as to compensate for the decrease in the axial load acting on the plate 103 as the centrifugal pressure plate assembly 200 tends to close as the rotational speed decreases.

[0104] In this way, the advantage is that, while maintaining the automatic disengagement of the centrifugal clutch as the vehicle approaches a stop with the engine idling and virtually no engine braking, it is possible to achieve an additional closing effect on the plate pack under disengagement and engine braking conditions.

[0105] In one embodiment, the angle between the second sliding surfaces 520 for reverse torque has an inclination equal to the first angle of the sliding surface 510 for traction torque, so that the pitch of the first helix corresponds to the pitch of the second helix. In this embodiment, the same characteristic curve between engine speed and maximum transmittable torque occurs in both acceleration conditions (driving torque, i.e., with respect to an increasing or stable engine speed for traveling in a horizontal plane) and engine braking conditions (reverse torque, i.e., a decrease in engine speed for traveling in a horizontal plane).

[0106] In an alternative preferred embodiment, the second angle, i.e., one of the sliding surfaces 520 for reverse torque, has a lower incline than the first angle, i.e., one of the sliding surfaces 510 for traction torque, and thus the pitch of the second helix is ​​greater than the pitch of the first helix. In this alternative embodiment, different characteristic curves are produced between engine speed and maximum transmitted torque, and in acceleration conditions, there is an effect of the hubs 101 and 102 moving closer to each other, which is more pronounced than in engine braking conditions, as is due to less aggressive clutch behavior at low engine speed and high gear conditions.

[0107] Figure 12 shows a cross-sectional view of an additional embodiment 100' of the clutch according to the present invention.

[0108] The centrifugal pressure plate assembly 200 further comprises multiple interface elements 213 between each pivot 203 and the mass carrier 201.

[0109] These interface elements 213 are configured to provide a localized reduction of friction and / or wear as the mass element 202 moves by rotating around the pivot 203. This is particularly effective in the case of the mass carrier 201 made of cast aluminum.

[0110] The centrifugal pressure plate assembly 200 also includes at least one overstroke spring 220 inserted between the clutch 100' cover and the mass carrier 201. The at least one overstroke spring 220 is configured to partially counteract a variable axial load when a load threshold is reached.

[0111] Figure 13 shows a three-dimensional view of an embodiment of the overstroke spring 220 according to the present invention.

[0112] In this embodiment, at least one overstroke spring 220 is of the disc spring type and includes an external shape such that, in the plurality of mass elements 202, the notches 221 engage with each of the protrusions of the mass carrier 201.

[0113] In one variation, at least one overstroke spring may be provided by one or more smaller diameter Smalley wave springs.

[0114] In light of the description provided herein, those skilled in the art may design further modifications and variations to meet indeterminate and specific needs. Therefore, the embodiments described herein should be understood as illustrative and non-limiting examples of the present invention.

Claims

1. A clutch, wherein the clutch is It comprises a fixed hub (101), a movable hub (102), and a plurality of plates (103) inserted between the fixed hub (101) and the movable hub (102), The fixed hub (101) and the movable hub (102) are configured to rotate together, and further configured to slide axially, moving apart or together, to transmit a variable axial load to the plurality of plates (103), and to selectively transmit torque acting on the clutch. The clutch further comprises a centrifugal pressure plate assembly (200) for at least partially controlling the variable axial load, and the centrifugal pressure plate assembly (200) A mass carrier (201) configured to rotate together with the clutch, A plurality of radially movable mass elements (202) within the centrifugal pressure plate assembly (200), wherein each mass element (202) is provided with a pivot (203) connected to the mass carrier (201) for displacement toward an external position under centrifugal effect, The displacement under centrifugal effect causes the plurality of mass elements (202) to further apply axial thrust to the thrust surface (204) of the centrifugal pressure plate assembly (200), bringing the movable hub (102) closer to the fixed hub (103) and increasing the variable axial load. Each mass element (202) comprises at least one rolling element (205) that contacts the thrust surface (204), A clutch having a thrust surface (204) with an inclined outer shape that rises toward the external position.

2. The clutch according to claim 1, wherein the inclined outer shape includes a curved portion (301), and the inclination of the curved portion (301) increases toward the external position.

3. The clutch according to claim 2, wherein the curved portion (301) defines a plurality of pressure angles (401; 402; 403), the pressure angles being defined between the direction of the variable axial load and the direction of the load transmitted between each of the rolling elements (205) and the thrust surface (204), and the pressure angles (401; 402; 403) change as they increase toward the external position.

4. The clutch according to claim 2 or 3, wherein the curved portion (301) is configured to provide a stable correlation between the rotational speed of the clutch and the variable axial load.

5. The clutch according to any one of claims 1 to 4, wherein the fixed hub (101) comprises a first sliding element (501), and the movable hub comprises a second sliding element (502), wherein the first sliding element (501) and the second sliding element (502) are configured to engage with each other and slide relative to each other when subjected to torque acting on the clutch so as to at least partially change the variable axial load.

6. The clutch according to claim 5, wherein the first sliding element (501) and the second sliding element (502) each include a first sliding surface (510) for traction torque, which is inclined according to a first helix and configured to coincide when the fixed hub (101) is subjected to traction torque, thereby increasing the variable axial load on the plurality of plates (103) by sliding the first sliding element (501) on the second sliding element (502) and bringing the movable hub (102) closer to the fixed hub (101).

7. The clutch according to claim 6, further comprising a second sliding surface (520) for the reverse torque, wherein the first sliding element (501) and the second sliding element (502) are inclined according to a second helix in the opposite rotation to the first helix, such that the first sliding element (501) slides on the second sliding element (502), respectively, and the movable hub (102) moves closer to the fixed hub (101), thereby increasing the variable axial load on the plurality of plates (103), and the fixed hub (101) is subjected to a reverse torque opposite to the traction torque.

8. The movable hub (102) further comprises a crown-shaped extension element (530), and the plurality of plates (103) are assembled around the extension element (530). The extension element (530) has an outer surface shaped to connect with the internal teeth of the driven plate among the plurality of plates (103), The clutch according to claim 7, wherein the second sliding element (502) of the movable hub (102) is adjacent to the inner surface of the extension element (530), and the second sliding element (502) is a substantially triangular or substantially trapezoidal convex portion.

9. The clutch according to claim 8, wherein the first sliding element (501) of the fixed hub (101) is a recess having an opening at its upper part, the opening being configured such that the second sliding element (502) passes through when the movable hub (102) is assembled on the fixed hub (101), and the first sliding element (501) is a substantially trapezoidal recess.

10. The clutch according to any one of claims 1 to 9, wherein the centrifugal pressure plate assembly (200) further comprises a plurality of interface elements (213) between each of the pivots (203) and the mass carrier (201), the plurality of interface elements (213) configured for localized reduction of friction and / or wear.

11. The clutch according to any one of claims 1 to 10, further comprising a housing (11) located outside the fixed hub (101) and rotatable about a rotation axis, wherein the fixed hub (101) is configured to be connected to a shaft (10) coaxial with the rotation axis, and the movable hub (102) is mounted axially on the fixed hub (101) along the rotation axis.

12. The clutch according to any one of claims 1 to 11, wherein each of the mass elements (202) comprises a body (206) including at least one rolling element (205), and further comprises a substantially elongated column element (207) connecting the pivot (203) to the body (206) and configured to increase the lever arm during the displacement under the centrifugal force effect.

13. The clutch according to claim 12, which is dependent on claim 11, wherein the mass element (202) has a center of mass inside the main body (206), and the column element (207) defines a pivot (203) that is radially outward from the center of mass with respect to the axis of rotation.

14. The clutch according to any one of claims 1 to 13, wherein the centrifugal pressure plate assembly (200) further comprises at least one overstroke spring (220) inserted between the clutch cover and the mass carrier (201), the at least one overstroke spring (220) being configured to partially counteract the variable axial load when a threshold is reached.

15. The clutch according to claim 14, wherein the at least one overstroke spring (220) has an outer shape such that in the plurality of mass elements (202), a notch (221) is configured to engage with each of the protrusions of the mass carrier (201).

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