Transmission module provided with a hydraulic actuator

Abstract

A transmission module (1) for a hybrid drive vehicle, configured to be interposed between an internal combustion engine (E) and a transmission (T) of the vehicle, comprising a tray-like support structure (5) configured to be fixed to the engine (E) and defining a housing (22) for a clutch (23) interposed between a crankshaft (7) of the internal combustion engine (E) and the module (1), and an actuator (34) for controlling the clutch (23), wherein the actuator (34) comprises an annular chamber (36) provided in the support structure (5) and open towards the housing (22) for the clutch, an annular piston (35) housed in the annular chamber (36) in a sliding manner in the axial direction and fixed in the angular direction, and a thrust member (46) coupled to the piston (35) in a rotationally free manner, coaxial to the piston (35) and operable to cooperate with a control member (30) of the clutch (23) under the thrust action of the piston (35).

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This patent application claims the benefit of Italian Patent Application No. 102019000025642, filed on December 27, 2019, the disclosure of which is incorporated herein by reference in its entirety. Technical Field

[0003] The present invention relates to a transmission module provided with a hydraulic actuator. The present invention is preferably, but not exclusively, applied in a hybrid transmission module provided with a hydraulically controlled clutch, which will be mentioned below without loss of generality. Background Art

[0004] As is known, hybrid-drive vehicles include an internal combustion engine and at least one electric machine that can function as a generator or as a motor to deliver torque along with (or instead of) the internal combustion engine, depending on vehicle operating conditions.

[0005] Configurations in which an electric motor connected between an internal combustion engine and a vehicle transmission are used are generally referred to as "P2." It is known to design modular units to be interposed between an internal combustion engine and a vehicle transmission (thus, currently referred to as "P2 modules") that, in addition to the electric motor, include one or more hydraulically controlled clutches for selectively connecting the internal combustion engine and / or the electric motor to the transmission and associated actuators and transmission elements.

[0006] In particular, hydraulically controlled clutches are typically provided with a spring applying an axial load, the spring being designed to hold the clutch plates together in a pack. Clutches of the aforementioned type are typically actuated open by means of a hydraulic actuator designed to generate an axial load opposing the axial load of the spring.

[0007] Hydraulic actuators for known clutches usually consist of an autonomous unit defining an internal chamber to which / from which pressurized oil can be supplied / discharged.

[0008] When the chamber is pressurized, the actuator expands axially, providing an axial load that overcomes the clutch spring force.

[0009] One problem associated with known actuators is their large overall size, in particular in the axial direction. Consequently, the use of said actuators in situations where installation space is limited, as in the case of the transmission module described above, is problematic. Summary of the Invention

[0010] It is an object of the present invention to provide a hydraulic actuator having particularly compact overall dimensions, in particular in the axial direction.

[0011] The above mentioned objects are achieved by a power module according to claim 1. BRIEF DESCRIPTION OF DRAWINGS

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

[0013] Figure 1 Front view of a hybrid power module produced according to the present application;

[0014] Figure 2 Schematic view of a hybrid powertrain of a vehicle comprising the module of the present application;

[0015] Figure 3 Figure 1 Explanatory view of the module of

[0016] Figure 4 Sectional view according to line IV-IV of the module of Figure 1

[0017] Figure 5 Partial enlarged sectional view according to line V-V of the module of Figure 1

[0018] Figure 6 Enlarged detail of the module of Figure 5 in which certain components are omitted for the sake of clarity; and

[0019] Figure 7 Schematic view of a damper of the module of Figure 1 DETAILED DESCRIPTION

[0020] With reference to Figures 1 to 3 , the reference 1 indicates in general a power module P2 designed to be connected between an internal combustion engine E and a transmission T of a hybrid drive vehicle, together forming a hybrid powertrain H.

[0021] The module 1 forms part of a hybrid unit 4, which, in addition to the module itself, also comprises an electric machine 2. Optionally, the hybrid unit 4 can also comprise one or more accessories, such as for example a compressor 3 for the air conditioning system of the vehicle. Figure 2 ).

[0022] Advantageously, the electric machine 2 is of the reversible type, i.e. it can operate as an electric motor (in combination with or in replacement of the internal combustion engine) to deliver torque to the transmission, or as a generator to generate electric power.

[0023] The module 1( Figures 3 to 5 ​​​​) mainly includes a tray-shaped supporting structure 5 and a transmission device 6, which is a chain transmission device in this example. The transmission device 6 is housed in the supporting structure 5 and is constructed to operably and selectively connect the crankshaft 7 of the internal combustion engine E, the motor 2 and the transmission device T to each other.

[0024] In the example shown, the transmission 6 comprises a crown wheel 8 with an axis A, selectively connectable to the crankshaft 7 as described below, and a pinion 9 with an axis B, designed to be connected to the motor 2. The axes A, B coincide, in use, with the axis of the crankshaft 7 of the engine E and with the axis of the motor 2, respectively. The transmission 6 also comprises a chain 10 engaged with the crown 8 and the pinion 9.

[0025] The supporting structure 5 has a substantially flat base wall 12 and a peripheral flange 13 extending perpendicularly thereto, forming a plurality of projections 14 in which holes are obtained for fastening the module 1 to the engine E. The base wall 12 and the peripheral flange 13 delimit a cavity housing the transmission 6 , said cavity being closed at the front by a cover 11 .

[0026] The base wall 12 forms a pair of through seats 15, 16 having axes A and B respectively ( Figure 4 ).

[0027] Motor 2( Figure 4 ) is assembled on a seat 16, on the opposite side of the transmission 6. The seat 16 houses the hub 17 of the pinion 9 and the associated bearing 19.

[0028] The crown 8 forms part of a torsional vibration damper 18, for example of the circumferential spring type, which is described briefly below as it is known per se and not part of the present invention. The damper 18 is supported by means of a bearing 25 housed in a seat 15 and is provided with a shaft 20 of axis A arranged through said seat.

[0029] The free end 21 of the shaft 20 is designed to engage an axial centering hole (not shown) of the crankshaft 7. The shaft 20 can be selectively connected to the crankshaft 7 by means of a clutch.

[0030] The base wall 12 of the support structure 5 is shaped to define a housing 22 for a clutch 23 on the opposite side of the transmission 6. The clutch 23 may be part of the module 1 or, as in the example described, a component distinct from the module 1 but complementary thereto.

[0031] The clutch 23 is briefly described here as needed to facilitate understanding of the present invention, but it does not constitute a part of the present invention. The clutch 23 includes an outer shell 24 and a hub 26 ( Figure 5), the outer shell 24 is fixed to the crankshaft 7 by means of axial screws 50, the hub 26 is in rotation integral with the shaft 20 by means of a slotted coupling 27.

[0032] The outer shell 24 Figure 5 ) houses at least one clutch disc 28 fixed in rotation to the hub 26 and at least one clutch disc 29 fixed in rotation to the outer shell.

[0033] In the normal clutch closed position, the clutch discs 28, 29 are axially slid and held in group by means of a clutch pressure plate spring 30, which comprises in a known manner an outer annular portion 31 and a plurality of elastic arms 32 extending integrally and radially towards the inside of the annular portion 31. The arms 32 are pivoted in a known manner to the support structure 5 in the vicinity of the annular portion 31 and are shaped and preloaded so as to exert an axial action designed to hold the clutch discs 28, 29 in group against the axial wall of the shell 24 in the engaged position.

[0034] The module 1 finally comprises an actuator 34 integrated in the support structure 5. Figure 6 The actuator 34 is shown in detail in the drawings and is designed to exert, in operation, an axial thrust action on the ends 33 of the arms 32 to move the annular portion 31 away from the clutch discs 28, 29, thus opening the clutch 23.

[0035] With particular reference to Figure 6 , the actuator 34 comprises an annular piston 35 having an axis A, axially movable in an annular chamber 36 obtained in the support structure 5 in a position coaxially external to the seat 15 and open frontally towards the clutch 23.

[0036] The piston 35 is radially guided by a pair of guide rings 37, 38 housed in respective external circumferential seats of the piston 35 arranged in the vicinity of the axial ends of the piston and in sliding contact with the external circumferential surface of the annular chamber 36.

[0037] The piston 35 is also provided with a pair of external annular seals 40 arranged between the guide rings 37, 38 and a pair of internal annular seals 41 in sliding contact with the internal circumferential surface of the annular chamber 36.

[0038] At the axial end of the piston 35 facing the clutch 23, said piston 35 has an internal annular flange 42 to which a tubular portion 43 extending towards the base wall 12 of the support structure 5 is integrally connected, thus defining an internal appendix of the piston 35 curved in the axial direction opposite to the clutch 23. The tubular portion 43 has an internal end shoulder 44 and houses a thrust ball bearing 45 axially abutting the shoulder 44.

[0039] The actuator 34 finally comprises a thrust member 46 which integrally comprises: a tubular sleeve 47 housed inside the bearing 45; a substantially flat annular portion 48 which extends radially outwards from the axial end of the sleeve 47 facing the clutch 23; and a thrust portion 49 defined by the outer radial edge of the annular portion 48 which is curved axially in the direction opposite to the piston 35, the thrust portion 49 axially facing the piston 35. The thrust portion 49 cooperates with the end 33 of the arm 32 of the clutch pressure plate spring 30.

[0040] Advantageously, the piston 35 is blocked in the direction of rotation with respect to the annular chamber 36 so as to avoid any unwanted rotation causing premature wear of the seals 40, 41 and of the guide rings 37, 38. This can be achieved by means of the axial pin 57 engaging the holes of the annular flange 42 of the respective piston 35 and of the holes of the thrust member 46. Figure 6 ).

[0041] The sleeve 47 forms a labyrinth seal 52 with tubular protrusions 51 which extend axially from the support structure 5 in a cantilevered manner so as to prevent the entry of dust into the area of the inner circumferential surface of the annular chamber 36.

[0042] The actuator 34 also comprises an annular bellows-shaped element 53 which is fixed on one side to the piston 35 and on the other side to an annular flange 54 applied in the front on the support structure 5 so as to prevent the entry of dust into the area of the outer circumferential surface of the annular chamber 36.

[0043] In addition to supporting the bellows-shaped element 53, the flange 54 also acts as a safety end stop for the piston 35 to prevent overtravel in case of overpressure or non-contact.

[0044] Advantageously, the support structure 5 defines an internal passage 55 for supplying / discharging oil to / from the annular chamber 36 of the actuator 34; the passage 55 Figure 5 ) establishes communication between the annular chamber 36 and a radial connection 56 arranged on the peripheral flange 13 of the support structure 5 and designed to be connected to a hydraulic control circuit.

[0045] The passage 55 is advantageously defined by two or more holes obtained in the thickness of the wall 12; said holes can be provided from the outside by means of a conventional drilling operation and said holes intersect each other so as to define a continuous path; if necessary, the openings of said holes can be plugged.

[0046] The damper 18 Figure 3 and Figure 5) comprising an annular casing 60 formed by a pair of half-shells 61, 62 on the periphery of which the crown wheel 8 of the transmission 6 is mounted. The damper 18 also comprises an actuator 63 comprising a disc 64 rigidly (and preferably integrally) connected to the shaft 20 and provided with two radial spokes 65 (only one of which can be seen in Figure 5 the interior of the annular casing 60. The latter forms a pair of diametrically opposite stops 66 defined by internal protrusions of the half-shells 61, 62.

[0047] As shown in the schematic view of Figure 7 between the spokes 65 and the stops 66, the purpose of which is to elastically couple the actuator 63 (and therefore the shaft 20) with the annular casing 60 (and therefore with the crown wheel 8 of the transmission 6) in order to filter the torsional vibrations transmitted from the crankshaft 7 to the electric machine 2 in use.

[0048] The flexible plate 67 constitutes the interface member between the module 1 and the transmission T, the flexible plate 67 being fixed to the disc 64 of the actuator 63.

[0049] The operation of the transmission module 1, which has partly emerged from the above description, is as follows.

[0050] In use, when the clutch 23 is closed, the shaft 20 is connected to the crankshaft 7 of the internal combustion engine (E), to the electric machine 2 by means of the damper 18 and the transmission 6, and to the vehicle transmission T by means of the flexible plate 67.

[0051] In this case, the electric machine 2 can be used both as a generator (for charging the battery during operation of the internal combustion engine, or as a regenerative brake), and as an electric motor for starting the internal combustion engine or for delivering additional torque (supercharging) during operation of the internal combustion engine.

[0052] When the clutch 23 is open, the electric motor can be used for electric driving, electric braking and coasting, while the internal combustion engine is off.

[0053] The use of the actuator 34 integrated in the support structure 5 allows a significant reduction in the axial size of the module 1 compared to conventional autonomous solutions, and therefore allows the module to be housed in the case of limited available axial space.

[0054] The integration of the actuator 34 in the support structure also allows dedicated fixing means to be avoided.

[0055] Finally, it is clear that modifications and variations can be made to the actuator 34 and to the module 1 comprising it, without departing from the scope defined by the claims.

Claims

1. A transmission module (1) for a hybrid drive vehicle, configured to be interposed between an internal combustion engine (E) and a transmission device (T) of the vehicle, comprising: - a support structure (5) of tray type, configured to be fixed to the engine (E) and to define a housing (22) for a clutch (23), - a hydraulic actuator (34) for controlling the clutch (23), - the hydraulic actuator (34) comprising: an annular chamber (36) provided in the support structure (5) and open towards the housing (22) for the clutch (23), an annular piston (35) axially mobile in the annular chamber (36), a thrust member (46) constrained in a rotationally free manner to the piston (35), coaxial to the piston (35) and configured to cooperate with a control member (30) of the clutch (23) under the thrust action of the piston (35), and a bearing (45) radially interposed between the annular piston (35) and the thrust member (46), - wherein the annular piston (35) comprises an internal tubular appendix (43) extending from an axial end of the piston (35) facing the housing (22) of the clutch (23) and axially curved in a direction opposite to the clutch (23), the bearing (45) being interposed between the appendix (43) and a sleeve (47) of the thrust member (46) housed inside the piston (35), and - the thrust member (46) comprising a thrust portion (49) axially facing the annular piston (35) and connected to the sleeve (47) by means of a substantially flat annular portion (48).

2. The module of claim 1, wherein, - the piston (35) is constrained to the support structure (5) so that it cannot rotate with respect to the annular chamber (36).

3. The module of claim 1, wherein, - the annular piston (35) is provided with seals (40, 41) cooperating with the inner and outer circumferential surfaces of the annular chamber (36).

4. The module of claim 3, wherein, - the annular piston (35) is provided with a pair of guide rings (37, 38) cooperating in a sliding manner with one of the circumferential surfaces of the annular chamber and arranged on axially opposite sides of the seal (40).

5. The module of claim 1, wherein, - the module comprises a safety end stop member (54) fixed to the support structure (5) and axially facing the annular piston (35) to prevent overtravel of the module towards the clutch (23).

6. The module of claim 1, wherein, - the actuator (34) comprises sealing means (52, 53) to prevent the entry of dust into the annular chamber (36).

7. The module of claim 1, wherein, - the support structure (5) is provided with internal ducts (55) for connecting the actuator (34) to a hydraulic control circuit. - the support structure (5) is provided with internal ducts (55) for connecting the actuator (34) to a hydraulic control circuit.

8. The module of claim 1, wherein, The module comprises a shaft (20) configured to be connected with the clutch (23) and a module transmission (6) housed in the support structure (5), and comprises at least a first rotary member (8) coupled to the shaft (20) and a second rotary member (9) rotatably coupled to the first rotary member (8) and configured to be connected to the electric motor (2).

9. The module of claim 8, wherein, The first rotary member (8) is coupled to the shaft (20) by means of a torsional vibration damper (18).

10. The module of claim 8, wherein, The support structure (5) comprises a first seat (15) through which the shaft (20) is supported and a second seat (16) through which the second rotary member (9) is supported.

11. The module of claim 8, wherein, The module transmission (6) is a chain transmission or a belt transmission.

12. The module of claim 8, wherein, The module transmission (6) is a gear transmission.

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