Wheel hub for axle of vehicle comprising improved integrated deceleration system

Abstract

A wheel hub (10) for an axle (4) of a vehicle (1), the wheel hub (10) comprising a deceleration unit (15) housed inside a chamber (13) defined between the wheel hub (10) and a housing (5) of the axle (4) and configured to vary a torque transmitted by a half axle (7a, 7b) of the axle (4) to the respective wheel hub (10), the deceleration unit (15) comprising a gear arrangement (16), the gear arrangement (16) is configured to define three transmission ratios depending on the position of the actuator arrangement (30) configured to move the half shafts (7a to 7b) along its axis (B).

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This patent application is related to Italian Patent Application No. 102022000009842 filed on May 12, 2022, the disclosure of which is incorporated herein in its entirety by reference. Technical Field

[0003] The invention relates to a wheel hub for an axle of a vehicle, in particular for an axle of a heavy vehicle, comprising a reduction system integrated in the hub itself. Background Art

[0004] As is known, in wheeled vehicles provided with at least an internal combustion engine it is of vital importance to reduce the torque from the drive shaft relative to the axle.

[0005] As is also known, due to known dynamic requirements during vehicle travel, vehicles are often provided with a differential unit configured to divide torque from a drive shaft between a pair of half-shafts of an axle.

[0006] The above-mentioned torque reduction is usually achieved by means of a known gear arrangement positioned between the drive shaft and the above-mentioned differential unit.

[0007] However, in the case of heavy vehicles, it is known that said reduction ratios are insufficient in number to provide a sufficient reduction ratio between the torque at the drive shaft and the torque at the wheels of the axle under various load conditions.

[0008] In fact, it is obvious that heavy vehicles, such as trucks, have to withstand a considerable difference in weight between an unloaded state and a maximum loaded state, and therefore the higher gears available are not necessarily the most suitable for the unloaded state of the vehicle.

[0009] For this purpose, reduction systems integrated in the wheel hub are known. However, said systems need further improvement in order to increase their efficiency.

[0010] Furthermore, known reduction systems do not allow the gears included in the system to engage while the vehicle is moving and therefore require the vehicle to be stopped, thereby increasing downtime.

[0011] Therefore, it is necessary to provide a reduction gear system for an axle of a vehicle that can solve the above problems.

[0012] The object of the present invention is to meet the above-mentioned needs in an optimized and inexpensive manner. Summary of the invention

[0013] The above objects are achieved by a wheel hub for an axle provided with an integrated reduction system and a vehicle as claimed in the appended claims. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] For a better understanding of the present invention, preferred embodiments are described below by way of non-limiting examples and with reference to the accompanying drawings, in which:

[0015] · Figure 1 is a schematic cross-sectional view of a vehicle provided with a wheel hub according to the present invention, viewed from above;

[0016] · Figures 2 to 4 The axle provided with the wheel hub according to the present invention is in a Figures 5 to 7 Schematic cross-sectional views of the different operating stages shown in ;

[0017] · Figures 5 to 7 are cross-sectional views of a vehicle hub according to the present invention in different stages of operation; and

[0018] · Figure 8 is a schematic diagram of a control system for a vehicle hub according to the present invention. DETAILED DESCRIPTION

[0019] Figure 1 A commercial or heavy vehicle 1 is illustrated, comprising a frame 2 extending along a longitudinal axis A and movable by means of wheels 3 carried by axles 4 .

[0020] like Figures 2 to 4 As illustrated in , the axle 4 comprises a housing 5 defining a space 6 suitable for at least partially housing a pair of half-axles 7a, 7b extending along an axis B transverse to the longitudinal axis A of the vehicle 1 .

[0021] In particular, the half shafts 7a, 7b are operatively connected at a first end to a transmission 8 of the vehicle 1 and at an opposite side to a respective wheel hub 10. In the illustrated example, the transmission 8 illustrates a bevel gear, but it is clear that it can be any torque transmitting device operatively connected to a torque source 9, say a powertrain such as an internal combustion engine.

[0022] In particular, the wheel hubs 10 are carried by the housing 5 in a freely rotatable manner and are each configured to cooperate with a respective end portion of the half shafts 7a, 7b, as described in detail below.

[0023] With regard to the wheel hubs 10 , for the sake of simplicity, reference will be made only to one of the wheel hubs 10 , e.g. the right-hand wheel hub, and obviously, the following considerations also apply in the same way to the left-hand wheel hub, since the structure described therein is mirrored relative to the longitudinal axis A of the vehicle 1 .

[0024] As described, the wheel hub 10 is supported in a freely rotatable manner relative to the housing 5, in particular the wheel hub 10 is hollow and coaxial relative to the transverse axis B. In the example described, the wheel hub 6 is supported by means of a supporting element 11, such as for example a pair of tapered bearings and sealing means, such as an O-ring.

[0025] In particular, the hub 10 comprises a main portion 10a of substantially cylindrical shape carried by the housing 2 and an annular portion 10b housed at the end portion of the housing 5 and carried by the main portion 10a. Advantageously, the main portion 10a and the annular portion 10b are coupled by screw means of known type and optionally by means of further intermediate parts, depending on the assembly required for the vehicle type and weight, which parts will therefore not be described in detail.

[0026] The cylindrical portion 10a together with the end portion of the shell 5 defines a chamber 13 which is axially delimited along the axis B by the axial wall 10c of the main portion 10a and on the other side by the end portion of the shell 5; the chamber 13 is radially delimited around the axis B by the inner surface of the main portion 10a of the wheel hub 10.

[0027] The wheel hub 10 is operatively connected to the axle 4 by means of a reduction unit 15, which is accommodated inside the chamber 13 and is configured to connect the wheel hub 10 to the half-shaft 7b at three different gear ratios, so that the speed / torque at the half-shaft 7b is different from the speed / torque at the wheel hub 10 according to the three different speed ratios.

[0028] In particular, the reduction unit 15 includes a gear device 16, which is configured to cooperate with a tooth portion 17 integral with the half-shaft 7b according to a first operating state, a second operating state and a third operating state, wherein the first operating state, the second operating state and the third operating state are characterized by different transmission ratios between the half-shaft 7b and the wheel hub 10.

[0029] In particular, the gearing 16 is a planetary gear train comprising a first plurality 18 ′ and a second plurality 18 ′ of satellite gears carried by respective pins 19 ′, 19 ″ integral with a carrier 21 and configured to mesh with a portion 22 integral with the housing 5 .

[0030] In particular, the carrier 21 is rigidly carried by the hub 10 , in detail, it is rigidly fixed to the cylindrical portion 10 a and has an annular shape extending radially from the cylindrical portion 10 a towards the space 13 , facing the wall 10 c .

[0031] In particular, portion 22 integral with housing 5 is advantageously in the shape of a bell open towards chamber 13 so as to face axial wall 6c. Portion 22 is configured to house satellite gears 18', 18". In particular, portion 22 defines a toothing 23 configured to mesh with satellite gears 18', 18".

[0032] The aforementioned toothing 17 thus defines a solar element of the transmission 16 , configured to cooperate selectively with one of the satellite gears 18 ′, 18 ″ or with the toothing 24 integral with the carrier 21 .

[0033] In particular, the second plurality of satellite gears 18" mesh and cooperate with the toothing 17 by means of a toothed wheel 25, which is operatively interposed between the satellite gears 18" and the toothing 17 and defines an external toothing 25' meshing with the satellite gears 18" and an internal toothing 25" meshing with the toothing 17.

[0034] Preferably, the pins 19 ′, 19 ″ are rigidly connected to each other and to the carrier 21 and define axes of rotation for the plurality of satellite gears 18 ′, 18 ″ which are parallel to each other and radially offset relative to the transverse axis B.

[0035] In detail, due to the presence of the additional toothed wheel 25 , the second plurality of satellite gears 18 ″ has a smaller diameter compared to the first plurality of satellite gears 18 ′.

[0036] Advantageously, the entire half-shaft 7b is moved along the axis B in order to move the toothing 17. In particular, the half-shaft 7b is moved relative to the transmission 8 as described below.

[0037] In particular, the half shaft 7b is actuated by an actuator device 30 operatively interposed between the housing and the half shaft 7b. In particular, the actuator device 30 is operatively interposed between the outer end 7b' of the half shaft 7b defining the above-mentioned toothing 17 and the inner end 7b" of the half shaft 7b cooperating with the transmission 8.

[0038] In particular, the actuator device 30 comprises a sleeve 31 carried so as to be free in rotation but linearly integral with the half-shaft 7b. In more detail, the sleeve 31 is carried by a roller bearing 32 arranged according to a suitable assembly arrangement.

[0039] The sleeve 31 includes a cylindrical body 31 ′ and a flange portion 31 ″ radially extending from an outer surface of the cylindrical body 31 ′.

[0040] In detail, the housing 5 defines a chamber 33 configured to accommodate the sleeve 31 in a sealed sliding manner, in particular configured to be in sliding contact with the cylindrical body 31'. The flange portion 31" is dimensioned to be in fluid-tight contact with the inner surface of the chamber 33, thereby dividing the chamber 33 into two parts 33', 33".

[0041] The actuator device 30 further comprises elastic means 34 configured to maintain the sleeve 31 in a predetermined position in the chamber 33. In particular, the actuator device 30 is configured to maintain the sleeve 31 in a rest configuration at a centerline extending along the transverse axis B relative to the chamber 33.

[0042] In more detail, the elastic means 34 comprises a first spring 34 ′ and a second spring 34 ″ which are positioned in respective parts of the chambers 33 ′, 33 ″ and are configured to exert a force between the housing 5 and the flange portion 31 ″.

[0043] In more detail, the first spring 34 ′ and the second spring 34 ″ are helical coil springs.

[0044] Furthermore, the portions 33', 33" are fluidly connected to a source of pressurized fluid, such as compressed air, of a vehicle (not shown) so as to be selectively positioned under pressure or to ambient pressure.

[0045] In particular, the first portion 33' is fluidly connected to a first conduit 35' and the second portion 33' is connected to a second conduit 35" that is fluidly connectable to a source of pressurized fluid.

[0046] For details, refer to Figure 8 , the vehicle 1 comprises a source of pressurized fluid 36, such as a compressed air tank, which is fluidly connected to the conduits 35', 35" via respective valve means 37', 37" configured to regulate the passage of air therethrough, for example.

[0047] The half shaft 7b is connected to the operating element 40, such as a bevel gear, in a rotationally integral but freely sliding manner. In particular, the half shaft 7b is connected to the operating element 40 by means of a grooved coupling between a toothed portion 41 provided on the inner surface of the operating element 40 and a toothed portion 42 provided on the outer surface of the operating element 40.

[0048] In more detail, the length of the grooved coupling along the axis B is such that the axle shaft 7b is in continuous torque engagement with the transmission 8, i.e. the operating element 40, throughout the movement of the axle shaft 7b actuated by the actuator device 30. Thus, the axle shaft 7b is continuously engaged due to the length of the grooved coupling, depending on the movement of the axle shaft 7b, such that the toothing 17 cooperates with the toothing 24 or with the satellite gears 18', 18".

[0049] Advantageously, the vehicle 1 also comprises an electronic control unit 50 and a plurality of sensors 51 to 58 suitable for detecting quantities related to different vehicle operating parameters; the control unit 50 comprises processing means electronically connected to the sensors 51 to 58 in order to acquire the data detected by the sensors 51 to 58 and control the passage of the pressurized fluid 35 ′, 35 ″ accordingly.

[0050] In particular, the sensors 51 to 58 can be connected to the control unit 50 by wires or electromagnetically and the control unit 50 is configured to control the valve devices 37 ′, 37 ″, the valve devices 37 ′, 37 ″ being advantageously solenoid valves.

[0051] In particular, the electronic unit 50 contains stored data related to the control of the actuator arrangement 30 and the valve arrangements 37 ′, 37 ″.

[0052] Furthermore, the vehicle 1 may include a control device (not shown) configured to change data stored in the control unit 50 so as to change the actuation states of the actuator device 30 and the valve devices 37 ′, 37 ″.

[0053] Preferably, the sensor device comprises at least some of the following sensor devices:

[0054] a load sensor 51 , such as a load cell, configured to detect the load of the suspension connecting the axle 4 to the frame 2 ;

[0055] A clutch sensor 52 , for example a position sensor connected to a clutch pedal, the clutch sensor 52 being configured to detect the opening of a control clutch of the transmission 8 ;

[0056] An accelerator sensor 53 , for example a position sensor connected to an accelerator pedal, the accelerator sensor 53 being configured to detect the acceleration of the vehicle 1 ;

[0057] An ignition sensor 54 , for example a motion sensor of a key ignition system, which is configured to detect the ignition of the vehicle 1 ;

[0058] A speed sensor 55 , such as a tone wheel, configured to detect the rotational speed of the output shaft of the powertrain 9 ;

[0059] a control sensor 56 , such as a button or an icon on the display, configured to detect the activation of the possibility of changing the wheel hub ratio;

[0060] a speed sensor 57, such as a tone wheel or an encoder, configured to detect the rotational speed of the axle 4 and hence the half-shafts 7a, 7b; and

[0061] A speed sensor 58 , such as an ABS sensor of the tone wheel or encoder type, configured to detect the speed of the wheel hub 10 .

[0062] The operation of the wheel hub according to the present invention described above is as follows.

[0063] exist Figures 2 to 5 In the first operating state at high speed illustrated in FIG, the toothing 17 cooperates with the toothing 24 of the carrier 21, since air is introduced into the portion 33' of the chamber 33 via the duct 35', thereby compressing the spring 34" and thus bringing the axle shaft 7b to its maximum extension position along the axis B. In said state, since the carrier 21 is fixed to the wheel hub 10, the torque provided to the axle shaft 7b by the transmission 8, i.e. by the operating element 40, is likewise transmitted to the wheel hub 10.

[0064] exist Figures 3 to 6 In the second operating state, shown in FIG. 1 , at medium speed, the toothing 17 cooperates with the first plurality of satellite gears 18 ′, since air is introduced into the portion 33 ″ of the chamber 33 through the duct 35 ″, thereby compressing the spring 34 ′ and thus bringing the axle shaft 7 b to its minimum extension position along the axis B. In said state, the torque supplied to the axle shaft 7 b by the transmission 8 , i.e. by the operating element 40 , is transmitted to the satellite gears 18 ′, which, by meshing on the toothing 23 of the element 22 , cause the corresponding pins 19 ′ of the drive carrier 21 to rotate at a speed different from that in the first operating state.

[0065] exist Figures 4 to 7 In the second operating state at low speed illustrated in the figure, the toothing 17 cooperates with the second plurality of satellite gears 18", since no air is introduced into the chamber 33 and therefore the springs 34', 34" maintain the sleeve 30 in an intermediate equilibrium position between the above-mentioned minimum extension and maximum extension of the half-shaft along the axis B. In said state, the torque supplied to the half-shaft 7b by the transmission 8, i.e. by the operating element 40, is transmitted to the satellite gears 18" via the toothed wheel 25. The satellite gears 18" rotate the corresponding pins 19' of the drive carrier 21 at a speed different from that in the first and second operating states by meshing on the toothing 23 of the element 22.

[0066] In light of the above, the present invention also relates to a method for controlling a wheel hub provided with a reduction unit 15 of the above-described type.

[0067] The method mainly comprises the following steps:

[0068] · detecting a plurality of physical quantities related to operating parameters of the vehicle 1;

[0069] · processing the detected physical quantity to identify the vehicle load state;

[0070] Check whether the vehicle load state meets the reduction ratio of the wheel hub 10;

[0071] If so, the ratio is maintained, otherwise the actuator device is controlled to switch to a different reduction ratio.

[0072] In particular, the control of the actuator arrangement 30 comprises sending a control signal to the valve arrangement 37 .

[0073] In particular, the above-mentioned method may be stored and processed in the above-mentioned control unit 50 , and the detected physical quantities may be some of the quantities detected by the sensor devices 51 to 58 .

[0074] The vehicle load status may be checked by checking the detected quantities against physical quantities stored in the control unit 50, for example by means of a look-up table (LUT) derived from specific experimental tests for a specific type of vehicle.

[0075] Otherwise, the above check may be performed by comparison with values ​​derived from mathematical interpolation between the physical quantities.

[0076] From the above, the advantages of a wheel hub for an axle of a vehicle comprising an integrated reduction system according to the invention are evident.

[0077] Thanks to the proposed system, it is possible to provide a reduction system integrated in a wheel hub which is versatile, compact, inexpensive and easy to assemble and maintain compared to known systems.

[0078] Due to the additional reduction system and the three gear ratios which can be selected depending on the vehicle type and size, fuel consumption and thus polluting emissions can be further reduced.

[0079] In particular, the use of a gear arrangement integrated in the wheel hub provides a high transmission ratio with highly loaded, robust gears suitable for heavy vehicle axles.

[0080] The use of a grooved coupling between the transmission and the half shaft allows the torque transmission to be continuously maintained when the operating gear in the wheel hub is changed, resulting in a particularly compact and stable arrangement.

[0081] Furthermore, the presence of two ducts that selectively inject air into two parts of the chamber of the actuator device allows the reduction ratio variation to be activated in a faster and more controlled manner. In particular, the variation can be controlled during vehicle movement.

[0082] In fact, thanks to the control method described, it is possible to engage the gears in the reduction unit 15 while the vehicle is moving.

[0083] The control may be automated and stored in an electronic unit, and the control variables may be pre-stored or modified by the driver.

[0084] Finally, it is clear that modifications and variations may be made to the wheel hub of a vehicle axle comprising an integrated reduction system according to the invention without departing from the scope of protection defined by the claims.

[0085] Obviously, as described, the housing 4 and the wheel hub 10 may have different forms and be produced in several different pieces.

[0086] The toothed wheels and gears described may vary, and it is likewise possible to provide elements not described but known for assembling the axle according to the invention.

[0087] Obviously, the above description relates to air actuation which is the most efficient and inexpensive, but equivalent actuator means configured for use with sleeve 31, such as electromagnetic actuators, mechanical actuators or fluid actuators, may be used instead of the air pressure means described in this application.

[0088] Furthermore, the described method may include different methods for checking the engagement state of the ratio between the wheel hub and the axle shaft by checking limit values ​​derived from mathematical interpolation or tabular relationships.

Claims

1. A wheel hub (10) for an axle (4) of a vehicle (1), include: a hollow portion (10a) configured to be carried on the housing (5) of the axle (4) in a freely rotatable manner about the axis (B) of the axle (4), the portion (10a) defining together with the housing (5) a chamber (13), a reduction unit (15) housed inside the chamber (13) and configured to modify the torque transmitted by the half shafts (7a, 7b) of the axle (4) and the wheel hub (10), the reduction unit (15) comprising a gearing (16), - actuator means (30) configured to move the half-shafts (7a, 7b) relative to the housing (A) along the axis (B), The gear device (16) comprises: a carrier (21) integral with the portion (10a) and defining a toothed portion (24); a first plurality of satellite gears (18') meshing with the housing (5) of the axle (4) and carried by the carrier (21), a second plurality of satellite gears (18") meshing with the housing (5) of the axle (4) and carried by the carrier (21), The half shafts (7a, 7b) carry a toothed portion (17), and the toothed portion (17) carried by the half shafts is configured to selectively cooperate with the following components: - the toothing (24) of the carrier, - said first plurality of satellite gears (18'), or - said second plurality of satellite gears (18"), Different transmission ratios are thereby defined between the half shafts (7a, 7b) and the wheel hub (10).

2. The wheel hub according to claim 1, in, The first plurality of satellite gears (18') and the second plurality of satellite gears (18") mesh with a toothing (23) made of a portion (22) integral with the housing (5).

3. The wheel hub according to claim 2, in, The portion (22) houses the first plurality of satellite gears (18') and the second plurality of satellite gears (18") inside the portion (22).

4. Wheel hub according to one of the preceding claims, in, The satellite gears (18', 18") are supported by respective pins (19', 19") which are rigidly connected to each other and to the carrier (21).

5. Wheel hub according to one of the preceding claims, in, The gearing (15) comprises a toothed wheel (25) operatively interposed between the toothing (17) carried by the half shaft (7b) and the second plurality of satellite gears (18").

6. Wheel hub according to one of the preceding claims, in, The actuator device (30) is freely rotatably carried to the half-shafts (7a, 7b) and is integral with the linear movement along the axis (B).

7. Wheel hub according to one of the preceding claims, in, The actuator device (30) comprises a sleeve (31) which is movable on the half shafts (7a, 7b) and defines a first portion (31') and a second portion (31"), the first portion (31') defining a chamber (33) together with the housing (5), the second portion (31") being in contact with the housing (5) to divide the chamber (33) into two portions (33', 33"), each of the portions (33', 33") being fluidly connected to a source (36) of pressurized fluid via a respective conduit (35', 35").

8. Wheel hub according to claim 7, comprising elastic means (34) operatively interposed between the second portion (31 ") and the casing (5).

9. The wheel hub according to claim 8, in, The elastic means (34) comprises a first spring (34') housed in the first portion (33') of the chamber (33) and a second spring (34") housed in the second portion (33") of the chamber (33).

10. An axle (4) for a vehicle, include: - a housing (5) which delimits a space (6) along an axis (B); a pair of half shafts (7a, 7b) at least partially housed in the space (6) and comprising respective inner ends (7b") cooperating with a transmission (8) of the vehicle (1) configured to supply driving torque to the half shafts (7a, 7b); - A wheel hub (10) according to one of the preceding claims, said wheel hub (10) being carried by said housing (5) in a rotationally free manner.

11. The axle according to claim 10, in, The inner end (7b") is operatively connected to an operating element (40) of the transmission device (8) via a groove.

12. A vehicle (1) comprising a frame (2), a drive train (9), a transmission (8) and at least one axle (4) according to claim 11.

13. The vehicle according to claim 12, comprising a source (36) of pressurized fluid, fluidically connected to the actuator device (30) via the conduit (35', 35"), and a valve device (37', 37") fluidly interposed on the conduit (35', 35") to regulate the passage of fluid under pressure.

14. The vehicle according to claim 13 comprises a control unit (50) and a plurality of sensor devices (51 to 58), the sensor devices (51 to 58) being configured to detect physical quantities related to an operating state of the vehicle (1), the control unit (50) comprising a processing device, the processing device being electrically connected to the sensor devices (51 to 58) for acquiring data detected by the sensor devices (51 to 58), processing the data and thereby controlling the valve device (37', 37") according to the data related to the operating state stored in the processing device.

15. The vehicle according to claim 14, comprising a control device configured to change data related to the operation amount stored in the electronic unit (50).

16. The vehicle according to claim 14 or 15, comprising at least some of the following sensor devices (51 to 58): a load sensor (51) configured to detect the load of a suspension connecting the axle (4) to the frame; a clutch sensor (52) configured to detect the opening of a control clutch of the transmission (8); An accelerator sensor (53) configured to detect the acceleration of the vehicle (1); an ignition sensor (54) configured to detect ignition of the vehicle (1); a speed sensor (55) configured to detect the rotational speed of an output shaft of the powertrain (9); a control sensor (56) configured to detect activation of a possibility to change the ratio of the wheel hub (10); a speed sensor (57) configured to detect the speed of the half-shafts (7a, 7b); and A speed sensor (58) configured to detect the speed of the wheel hub (10).

17. A method for controlling a wheel hub (10) in a vehicle according to claim 16, the method comprising the steps of: · detecting a plurality of physical quantities related to operating parameters of the vehicle (1); · Processing the detected physical quantity to identify the vehicle load state; Checking whether the vehicle load state conforms to the reduction ratio of the wheel hub (10); If the vehicle load conditions are met, the ratio is maintained, otherwise the actuator device (30) is controlled to switch to a different reduction ratio.

18. The method according to claim 17, in, Said controlling of said actuator means (30) comprises sending a signal to control said valve means (37).

19. The method according to claim 17 or 18, in, Said verification of the vehicle load state comprises a comparison with a value stored in said control unit (50) and / or a comparison with respect to a calculation by mathematical interpolation of said physical quantity.

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