Improved filter pulley

Abstract

A filtering pulley comprising: a hub configured to be fixed to a shaft rotating about an axis; a crown coaxial and rotationally free mounted on said hub; a plurality of elastic groups arranged circumferentially with respect to said hub and said crown and each clamped between a pair of first elements integral with said hub and between a pair of second elements integral with said crown, said first elements comprising at least two spokes carried by an actuator, wherein said actuator is made up of two parts selectively engaged between them to selectively connect the crown and the hub.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims the benefit of Italian Patent Application No. 102020000009289, filed on April 28, 2020, the disclosure of which is incorporated herein by reference in its entirety. Technical Field

[0003] The present invention relates to a filter pulley, in particular to a pulley for a crankshaft in an auxiliary transmission device of an internal combustion engine. Background Art

[0004] It is well known that the drive shaft in an internal combustion engine is subject to torsional vibrations due to the periodic stresses caused by combustion in the cylinders. These vibrations are particularly severe during startup and at low engine speeds, as well as when using special design concepts such as dual-clutch transmissions, start-stop systems, or hybrid systems.

[0005] Torsional vibrations lead to irregular rotation of the drive pulley of the auxiliary transmission, which is transmitted to the auxiliary component via the conveyor belt, which is therefore subject to periodic variations in tension.

[0006] In order to "filter" the torsional oscillations transmitted from the crankshaft to the belt, a filter pulley is usually used as a drive pulley, which is provided with a hub integral with the drive shaft, a crown cooperating with the belt and one or more elastic elements, through which the driving torque is transmitted from the hub to the crown.

[0007] Furthermore, in hybrid systems, it is considered desirable to decouple the crankshaft from the rest of the transmission. An example of such a need is the use of an air conditioning system, whose compressor is coupled to the transmission even when the engine is off and driven by one or more motor-generators configured to generate torque rather than absorb it as would normally be the case. In this case, the inertia of the hot internal combustion engine creates a passive load, thus tending to reduce the efficiency of the transmission by dissipating energy.

[0008] Systems are known that decouple the pulley from the crankshaft of the internal combustion engine when the electric motor is active and the internal combustion engine is not in use.

[0009] However, these systems are particularly complex and heavy, and therefore expensive. In addition, these systems involve the use of disc clutches, which cannot precisely control the coupling and disengagement of the pulley to the crankshaft. Or there are purely one-way freewheeling systems.

[0010] The object of the present invention is to provide a filter pulley that solves the above mentioned technical problems in a simple and inexpensive manner. Summary of the Invention

[0011] The above objectives are achieved by means of the filter pulley and transmission system of the present application. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] For a better understanding of the present invention, preferred embodiments are described below by way of non-limiting examples with reference to the accompanying drawings, in which:

[0013] Figure 1 is a schematic diagram of a transmission system according to one aspect of the present invention;

[0014] Figure 2 is a perspective view and a partial cross-sectional view of a pulley according to the present invention, with some components removed for clarity;

[0015] Figure 3 yes Figure 2 A perspective view of a portion of a pulley in FIG, with some components removed for clarity;

[0016] Figure 4 yes Figure 1 A front view of the pulley in FIG, with some parts removed for clarity;

[0017] Figure 5 is a radial cross-sectional view of a portion of a pulley according to the present invention in a first operating state; and

[0018] Figure 6 is a radial sectional view of a portion of a pulley according to the invention in a first operating state. DETAILED DESCRIPTION

[0019] Figure 1 A drive train 100 of a vehicle is depicted, essentially comprising an internal combustion engine 101 , at least one electric motor / generator 102 and at least one auxiliary element 103 (eg a compressor or a water pump of the vehicle's air conditioning circuit).

[0020] Each of the internal combustion engine 101, the electric motor / generator 102 and the auxiliary element 103 comprises a corresponding shaft 101', 102', 103' and a corresponding pulley 104, 105, for example known in the art, the corresponding shaft 101', 102', 103' being coupled to a pulley, in particular a pulley 1 for the internal combustion engine 101 according to the present invention, the corresponding pulleys 104, 105 being used for the electric motor / generator 102 and the auxiliary element 103.

[0021] The transmission system 100 comprises an endless transmission element 106 (e.g. a belt 107 ), preferably a poly-V or toothed belt, configured in known manner to cooperate with pulleys 1 , 104 and 105 to allow torque to be transmitted between the internal combustion engine 101 , the electric motor 102 and the auxiliary element 103 .

[0022] Figures 2 to 4 A filter pulley 1 is shown, comprising a hub 2 with an axis A, designed to be connected to a shaft 101 ′, i.e. the crankshaft of an internal combustion engine 101, and an annular crown 3, which is externally coaxial with the hub 2 and is supported on the hub 2 in a freely rotatable manner via rolling means 4, such as bearings, preferably rolling bearings.

[0023] The crown 3 comprises an annular portion 5 provided with a profile 6 designed to cooperate with a poly-V belt (not shown). The crown 3 also comprises a radial wall 7 and a substantially cylindrical inner wall 8 having an axis A, integral with the annular portion 5 and preferably in a single piece therewith, extending radially towards the hub 2.

[0024] The crown 3 carries and is integral with a closing element 11 comprising an outer cylindrical wall 12 of axis A and a flat radial annular wall 13 extending radially from the wall 12 towards the axis A and cantilevered.

[0025] The closing element 11 is press-fitted into the crown 3 so as to form an annular chamber 15 radially sandwiched between one wall 12 and the other wall 8 and axially delimited by one wall 7 and the other wall 13. Finally, the closing element 11 comprises two diametrically opposed protrusions 16, 17 which extend axially from the wall 13 inside the chamber 15.

[0026] The wall 7 of the crown 3 forms a projection (not shown) corresponding to and facing the projections 16 , 17 of the closing element 11 .

[0027] The pulley 1 may also be provided with a dynamic damper, of a known type and not shown, which is integral with the hub 2 and not depicted for the sake of simplicity. Furthermore, the pulley 1 comprises a plurality (for example two) of arcuate elastic groups 20 freely arranged circumferentially in respective portions 15 a, 15 b of the chamber 15 delimited by the protrusions 16 and 17. The travel of the elastic groups 20 in the respective portions 15 a, 15 b is given by the angular gap α between each elastic group 20, said elastic groups 20 being arranged in contact with one of the protrusions 16, 17 and the other protrusion 17, 16.

[0028] Each elastic group 20 preferably comprises a pair of arched helical springs 21 , 22 , advantageously but not necessarily placed in series with each other.

[0029] Even more preferably, each elastic group 20 is mounted between a respective end gasket 23 and an optional intermediate gasket 24 .

[0030] If there are two springs 21 , 22 , they have different stiffnesses, more precisely a greater and a lesser stiffness as will be described in further detail below.

[0031] The spacer 23 preferably comprises, each, an arched portion 25 internally surrounding an end portion of the respective spring 21, 22 and a head 46 defining an axial support for said end portion. The spacer 44 comprises an arched portion 47, which internally surrounds respective opposite end portions of the springs 21, 22, and an intermediate radial partition 48, which is arranged between the two springs 21, 22.

[0032] Finally, the pulley 1 comprises an actuator 30 carried by the hub 2, as described below. The actuator 30 has two spokes 31, which are free to move in the circumferential direction in the chamber 15 and are designed to interact with the elastic group 20. It is assumed that the actuator 30 is arranged so that each spoke 31 is equally angularly spaced with respect to the elastic group 20, the angle formed between each spoke 31 and each elastic group 20 will be equal to σ / 2, where σ indicates the total angular clearance between the spoke 31 and the elastic group 20.

[0033] Therefore, the hub 2 and the crown 3 can be rotated with respect to each other in an angular range or free angle equal to the sum of the above-mentioned angular clearances a and σ, without any torque transmission.

[0034] Furthermore, as shown in Figure 5 and 6 , the spokes 31 are placed in radial coincidence with the rolling means 4 and also advantageously with the centre line of the portion 6, to minimize the tilting torque in the pulley 1.

[0035] According to one aspect of the application, the actuator 30 comprises a coupling portion 32 carried by the hub 2 and an actuation portion 33 carrying the spokes 31 as described above. The coupling portion 32 and the actuation portion 33 are configured so that they can be selectively coupled so as to be, in a first operating condition, integrally coupled with the actuation portion 33 by the coupling portion 32 driven by the hub 2, causing the latter to be also driven by the hub, so as to be, in a second operating condition, operatively separated from the actuation portion 33 so that the latter cannot transmit torque with respect to the hub 2.

[0036] Advantageously, the coupling portion 32 is configured to move with respect to the hub 2 along the axis A, but is rotationally fixed with respect to the latter, while the actuation portion 33 is configured to be freely rotatably carried on the crown 3 about the axis A, but is fixed with respect to the movement along the latter.

[0037] The actuation portion 33 is preferably substantially annular, so as to define an outer surface from which the spokes 31 protrude and an inner surface which is radially larger than the wall 8 so as to surround the wall 8.

[0038] In accordance with the embodiment described, the actuating portion 33 is supported in a freely rotatable manner at least radially by one wall 8 and at least axially by the other wall 13. This freely rotatable support is advantageously achieved by corresponding supporting means 34, such as rotating plastic supporting bushes or rings, respectively sandwiched between the actuating portion 33 and one wall 8 and between the actuating portion 33 and the other wall 13.

[0039] Advantageously, the coupling portion 32 is free to move on the hub 2 by means of a grooved coupling 35 made between the hub 2 and the coupling portion 32. The latter preferably has a substantially annular shape about the axis A, with an inner diameter sized so as to surround the hub 2 externally.

[0040] The slotted coupling 35 is thus made between the inner surface of the coupling portion 32 and the outer surface of the hub 2, so that a plurality of teeth extending from either the coupling portion 32 or the hub cooperate with corresponding seats made in the other. In the embodiment described, the hub 2 defines the number of teeth, while the coupling portion 32 defines the number of seats in which the teeth can cooperate.

[0041] According to one aspect of the present invention, the connecting portion 32 and the actuating portion 33 are selectively matched by a shape connecting member, which can be engaged in a first state and cannot be engaged in a second state. In the first state, the connecting portion 32 is placed at a minimum distance relative to the axial position of the spoke 31, and in the second state, the connecting portion 32 is placed at a maximum distance relative to the axial position of the spoke 31.

[0042] Advantageously, but not necessarily, the form coupling element is a slotted coupling element 36 between the coupling portion 32 and the actuating portion 33. In the case described, a number of teeth defined in the former can selectively engage with corresponding seats made in the latter. Preferably, the teeth are angularly equidistant from one another, depending on their number around axis A, as are the corresponding seats. Furthermore, the teeth or coupling element can be made with shaped sides to optimize engagement, for example by having teeth with a prismatic cross-section.

[0043] The coupling portion 32 is maintained in the first state by a force imparted by elastic means 37, preferably clamped axially between the hub 2 and the coupling portion 32. These elastic means may advantageously comprise Belleville washers.

[0044] The coupling portion 32 is actuated in its movement on the hub 2 along the axis A by actuating means 38 configured to impart a force greater than that exerted by the elastic means 37 .

[0045] These actuating means 38 preferably comprise magnetic attraction means (e.g., electromagnets 39 electrically connected to a power source such as a battery (not shown) or the motor-generator 102). Thus, the disengaging portion 32 is made of a material intended to be influenced by the magnetic field of the electromagnets 39 (e.g., a ferromagnetic material).

[0046] The actuating device 38 is also electrically connected to an electronic unit 40 which is configured to control the operation of the actuating device 38 so as to enable the coupling portion to be changed between the two states.

[0047] The electronic unit 40 may be a vehicle ECU or an internal combustion engine 101 and is electrically connected to a motor / generator 102 , sensors (not shown) configured to detect operating parameters of the internal combustion engine 101 , and / or elements 103 .

[0048] The electronic unit 40 includes a processing device configured to: detect signals from components electrically connected to the processing device; process these signals, possibly by storing these signals or using data previously stored in the processing device; and send control signals to the above-mentioned components based on the aforementioned processing.

[0049] The actuating means 38 are advantageously carried by the hub 2, which is preferably made of two parts 2a, 2b rigidly connected to each other, for example laid flat on top of the other. According to the embodiment shown, the hub part 2a supports the rolling means 4 and the actuator 30, while the part 2b is configured to support the actuating means 38.

[0050] The parts 2a and 2b of the hub 2 are preferably substantially similar in shape to each other; in addition, the part 2b includes a flange 2c extending radially from the end edge of the annular body of the part 2b. The end edge is the edge that contacts and cooperates with the part 2a to achieve its rigid connection.

[0051] According to the configuration described above, the elastic means 37, as described above, are advantageously interposed axially between the flange 2c and the coupling portion 32, while the actuating means 38 are always carried by the flange 2c but on the opposite side relative to the elastic means 37. To this end, the flange 2c defines a seat 41, advantageously annular, configured to house the electromagnet 39, also advantageously annular.

[0052] According to the configuration as described above, the disengagement portion 32 is placed at the maximum distance relative to the flange 2c in the above-mentioned first operating state, while in the second state, the coupling portion 32 is placed at the minimum distance relative to the flange 2c, making better contact with the flange 2c.

[0053] Furthermore, the pulley 1 includes a cover 42 configured to engage in contact between the crown 3 and the hub 2 to prevent external communication with the aforementioned components. According to the embodiment, all the functional components described, except for the electromagnet 2, are isolated from the external environment by the cover 42, so that the oil contained inside the pulley 1 for lubricating the aforementioned components does not contaminate / leak to the outside.

[0054] Advantageously, the cover 42 is fixed to the crown 3, for example by pressure, while being supported to slide on the hub 2. In particular, the cover 42 may comprise an annular wall 43 that engages in contact with the portion 5 of the crown 3 and a cylindrical wall 44 that extends freely from the inner radial edge of the annular wall 43 and is configured to engage and slide with the flange 2c of the hub 2. The sliding engagement may be achieved by a rotating sealing ring 45.

[0055] The pulley 1 may further include a damper configured to damp the relative oscillation between the hub 2 and the crown 3 , but for the sake of brevity, no additional description is given herein.

[0056] The operation of the pulley 1 according to the present invention as described above is as follows.

[0057] In the first state, in which the coupling portion 32 is operatively connected to the actuating portion 33, torque can be transmitted between the hub 2 and the crown 3 according to different operating phases of the system 100. This configuration can be used for normal system operation 100, in which the internal combustion engine 101 provides torque for the entire system, or for hybrid operation, in which some torque is absorbed or additionally provided by the electric motor / generator 102.

[0058] In this configuration, the electromagnet 39 is deactivated and the coupling portion 32 is therefore held in its position operatively connected to the actuating portion 33 by the force of the elastic means 37 .

[0059] In a first operating phase, called "drive mode" and constituting the normal operating mode of the pulley 1, when the drive shaft 101 ′ drives the belt 107, the speed of the hub 2 tends to exceed the speed of the crown 3. Consequently, the spokes 31 of the actuator 30, as soon as the free angle α formed by the sum of the angular gap σ between the spokes 31 and the elastic group 20 and the angular travel α of the elastic group 20, as described above, begin to transmit the torque to the protrusions 16, 17 through the intervention of the respective elastic group 20, thus defining the transmission characteristics of the pulley 1.

[0060] What is described for the driving mode occurs symmetrically in a situation called “overrun”, in which the speed of the crown 3 tends to exceed the speed of the hub 2 .

[0061] In the second state, in which the coupling portion 32 is operatively separated from the actuating portion 33, torque cannot be transmitted between the hub 2 and the crown 3. This state may be useful if it is desired to operate the system 100 in a fully / primarily electric mode, i.e., with the internal combustion engine 101 off or idling and the electric motor / generator 102 providing torque to the system 100.

[0062] In this configuration, the electromagnet 39 is activated and the coupling part 32 is therefore attracted by the electromagnetic force exerted by the electromagnet 39, thereby overcoming the force of the elastic means 37. This force causes it to compress the elastic means 37 and brings the coupling part 32 to a position close to the flange 2 c, thereby disengaging the slotted coupling 36 and thus disconnecting it from the actuating part 33.

[0063] The control of the actuating device is effected by means of an electronic unit 40 which processes the data received from the electric motor / generator 102 , the functional element 103 and the internal combustion engine 101 in order to control the actuating device 38 and thus the electromagnet 39 .

[0064] The advantages of the pulley 1 according to the invention thus become apparent.

[0065] By means of the pulley 1 described, it is possible to provide a compact, stable and rapid disengagement of the crown 3 relative to the hub 2 , depending on the state of the system 100 .

[0066] In fact, coupling the two separated elements by a shape coupling such as a groove coupling makes it possible to switch between coupling and decoupling the crown 3 and the hub 2 in a compact manner without adding an additional element such as a clutch.

[0067] Likewise, control using electromagnetic means is simple, inexpensive, and can be easily controlled using an electronic unit configured to control the entire system 100 .

[0068] Finally, it is clear that modifications and variations may be made to the pulley 1 described without departing from the scope of protection defined in the claims.

[0069] It is obvious that the form of the elements described may vary within the scope of the claims included below.It is also clear that the elastic group 20, elastic means 37, support and damping elements shown may be replaced by devices having the same function.

[0070] Likewise, it is obvious that the drive device 38 can vary with respect to what has already been described, both in terms of type and in terms of the mutual arrangement and coupling of the parts 32 , 33 of the actuator 31 .

[0071] Alternatively, as described above, the slotted couplings 35, 36 may be replaced with similarly shaped couplings.

[0072] Likewise, the actuation device 38 can comprise different types of actuators, for example mechanical (for example screw type), pneumatic or hydraulic.

Claims

1. A filter pulley (1), comprising: a hub (2) configured to be fixed to a shaft for rotation about an axis (A); a crown (3) coaxially and rotatably mounted on the hub (2); a plurality of elastic groups (20) arranged circumferentially relative to the hub (2) and the crown (3), and each of the elastic groups (20) being sandwiched between a pair of first elements integral with the hub (2) and between a pair of second elements (16, 17) integral with the crown (3), the first elements comprising at least two spokes (31) carried by an actuator (30), The actuator (30) is characterized in that the actuator (30) includes a coupling portion (32) and an actuating portion (33), the coupling portion (32) being slidably carried by the hub (2) but rotationally fixed relative to the axis (A), the actuating portion (33) defining the spokes (31) and being rotationally free by the crown (3) but fixed to translation relative to the axis (A), the coupling portion (32) and the actuating portion (33) being configured to define a first configuration and a second configuration, in which the coupling portion (32) and the actuating portion (33) cooperate to enable the crown (3) to be operatively connected to the hub (2), and in which the coupling portion (32) and the actuating portion (33) are operatively separated to enable the crown (3) to be operatively disconnected from the hub (2).

2. The pulley according to claim 1, wherein The coupling portion (32) is coupled to the hub (2) via a form coupling (35).

3. The pulley according to claim 1, wherein The coupling portion (32) and the actuating portion (33) define a coupling having a gear shape according to a position of the coupling portion (32) relative to the hub (2).

4. The pulley according to claim 2, wherein: The shape coupling is a groove coupling (36).

5. The pulley according to claim 1, comprising an actuating device (38) configured to allow the coupling portion (32) and the actuating portion (33) of the actuator (30) to change from the first configuration to the second configuration.

6. The pulley according to claim 5, wherein: The actuating device (38) comprises an electromagnet (39).

7. Pulley according to claim 1, comprising elastic means (37) configured to exert a force on the coupling portion (32) to maintain it in the first configuration.

8. The pulley according to claim 7, wherein: The elastic device (37) is axially sandwiched between the coupling portion (32) and the wheel hub (2).

9. Pulley according to claim 1, comprising sliding support means (34) for supporting said actuating portion (33) on said crown (3).

10. The pulley according to claim 5, comprising an electronic unit (40) configured to control the actuating device (38).

11. The pulley according to claim 1 comprises a cover (42) and a rotation support device (45), wherein the cover (42) comprises an edge that cooperates with one edge between the crown (3) and the hub (2) and a second edge that cooperates with the rotation support device (45), and the rotation support device (45) is clamped between the second edge and the other edge between the crown (3) and the hub (2), and the cover (42) isolates the actuator (30) and the elastic group (20) from the outside.

12. The pulley according to claim 1, wherein The hub (2) is made of two parts rigidly connected to each other, a first part (2a) configured to support the crown (3) and the actuating part (33), and a second part (2b) configured to support the coupling part (32).

13. The pulley according to claim 1, wherein Each elastic group (20) forms a respective angular gap (σ, α) with the first element and the second element (16, 17), and the crown (3) and the hub (2) have a relative rotational freedom angle (β) equal to the sum of the angular gaps (σ, α).

14. The pulley according to claim 1, wherein The pulley comprises a damper configured to damp relative oscillations between the hub (2) and the crown (3).

15. The pulley according to claim 1, wherein The pulley includes a dynamic damper.

16. A transmission system (100) for a vehicle, comprising: An internal combustion engine (101) and at least one electric motor / generator (102), each of the internal combustion engine (101) and the at least one electric motor / generator (102) comprising a respective pulley (1, 105), the pulleys (1, 105) being configured to cooperate with an element of an endless transmission (106) for transmitting torque between the internal combustion engine (101) and the at least one electric motor / generator (102), at least the pulley (1) of the internal combustion engine (101) being manufactured according to claim 1.

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