CROSS-REFERENCE TO RELATED APPLICATIONS

This patent application claims priority from Italian patent application no. 102019000009624 filed on 20/06/2019, the entire disclosure of which is incorporated herein by

reference .

TECHNICAL FIELD

The present invention concerns a transmission module for a hybrid drive vehicle, and in particular a transmission module adapted to be interposed between an internal combustion engine and a transmission of a hybrid drive vehicle.

BACKGROUND ART

As is known, hybrid drive vehicles comprise an internal combustion engine and at least an electric machine which can be used as generator or motor for delivering torque in combination with (or alternatively to) the internal combustion engine, according to the vehicle operating conditions.

A configuration in which an electric machine is used connected between the internal combustion engine and the vehicle transmission is conventionally called "P2". Modular units are known adapted to be interposed between the internal combustion engine and the transmission of a vehicle (and therefore currently called "P2 modules") which comprise, in addition to the electric machine, one or more clutches to selectively connect to the transmission the internal combustion engine and/or the electric machine, in addition to the relative actuators and transmission elements.

A problem connected with the known P2 modules, which limits the application thereof, is the relatively large axial dimension . A further problem is the complexity of installation, due to the fact that said modules comprise relatively heavy parts (for example the electric machine) which have to be accurately centred and supported both with respect to the internal combustion engine and with respect to the module being installed .

DISCLOSURE OF INVENTION

The object of the present invention is the production of a P2 transmission module, which solves the problems connected with the known modules specified above.

The above-mentioned object is achieved by a module according to claim 1.

BRIEF DESCRIPTION OF THE DRAWINGS

For a better understanding of the present invention, a preferred embodiment is described below with reference to the attached drawings, in which:

figure 1 is a perspective view of a transmission module according to the present invention;

figure 2 is a diagram of a hybrid drive unit of a vehicle comprising the module of the invention;

figure 3 is an exploded perspective view of the module of figure 1;

figures 4, 5 and 6 are front elevation, rear perspective and rear elevation views respectively of a hybrid unit comprising the transmission module of figure 1;

figures 7 and 8 are sections along the lines VII-VII and VIII- VIII respectively of figure 6;

figure 9 is an exploded perspective view of the hybrid unit; figure 10 and figure 11 are perspective views of respective details of the unit of figure 9;

figure 12 is an exploded perspective view of a damper of the transmission module of figure 1; figure 13 and figure 14 are perspective views from the opposite sides of a detail of the damper of figure 12; and figure 15 is a perspective view of a second embodiment of the transmission module according to the invention.

BEST MODE FOR CARRYING OUT THE INVENTION

With reference to figures 1 and 2, the number 1 indicates overall a P2 transmission module adapted to be connected between an internal combustion engine E and a transmission T of a hybrid drive vehicle, forming overall a hybrid drive unit

H.

The module 1 is part of a hybrid unit 4 (figures 3-11) comprising, apart from the module itself, an electric machine 2 and one or more accessories such as, for example, a compressor 3 for an air conditioning system of the vehicle. The electric machine 2 is expediently of reversible type, namely it can operate as an electric motor to deliver torque to the transmission (in combination with or alternatively to the internal combustion engine) or as a generator to generate electric power.

The module 1 essentially comprises a tray-like support structure 5 and a transmission 6, in this example by belt, housed in the support structure 5 and configured to operatively and selectively connect to one another a crankshaft 7 of the internal combustion engine E, the electric machine 2 and the transmission T.

The support structure 5 has a substantially flat base wall 8 and a perimeter flange 9 extending perpendicular to it and forming a plurality of enlargements 10 in which the holes are obtained for fastening the module 1 to the engine E. From the base wall 8 respective tubular appendages 15, 16, 17 extend axially (figure 3), each of which internally defining a through seat. The tubular appendages 15, 16, 17 have axes A, B and C coinciding respectively with the axis of the crankshaft 7 of the engine E, with the axis of the electric machine 2 and with the axis of the compressor 3, as will be better described below .

In the example illustrated, as can be clearly seen in figures 2, 4 and 9, the transmission 6 comprises a first pulley 20 with axis A selectively connectable to the crankshaft 7 by means of a decoupling clutch 21, also forming part of the hybrid unit 4, and a torsional vibration damper 22 (figures 7 and 8) described in detail below.

The transmission 6 further comprises a second pulley 23 having axis B adapted to be connected to the electric machine 2, and a third pulley 24 having axis C adapted to be connected to the compressor 3. For this purpose, the second pulley 23 and the third pulley 24 are provided with respective shafts 25, 26 which are housed in the respective tubular appendages 16, 17 and are supported therein by means of respective bearings 27,

28 (figures 10 and 11) .

The transmission 6 comprises a belt 29, preferably of poly-V type, which is wound around the pulleys 20, 23 and 24 and rotationally connects them to one another.

Lastly, the transmission 6 comprises a tensioner 30 with double arm having a first tensioner pulley 31 and a second tensioner pulley 32 which act on sections 29a, 29b of the belt

29 between the second pulley 23 and the third pulley 24 and, respectively, between the first pulley 20 and the second pulley 23 under the thrust of elastic means not illustrated.

The tensioner 30 comprises (figures 4 and 10) :

an annular base 33 fixed to the structure 5 around the tubular appendage 16,

- a first annular arm 34 revolving on the base 33, on which the first tensioner pulley 31 is supported idle in an eccentric position, and

- a second arm 35 having a first tubular end 36 hinged to the first arm 20 and a second end 37 on which the second tensioner pulley 32 is mounted idle.

The cited elastic means can consist of a spring (not illustrated) housed in the first end 36 of the second arm 35, which is configured so as to push the second arm 35 towards the first tensioner pulley 31.

Alternatively to the example described, the tensioner can be of any other type with double arm adapted to maintain a sufficient level of tension in the two sections 29a and 29b of the belt 29, each of which can be the slack section of the belt 29 depending on the operating conditions.

According to the description, the belt 29 can be premounted on the support structure 5 and tensioned prior to assembly of the support structure 5 on the engine E.

As can be clearly seen in figure 8, the base wall 8 is shaped so as to define, on the opposite side of the transmission 6, a housing 38 for the clutch 21. The clutch 21 can be part of the module 1 or, as in the example described, a unit distinct from the module 1 and complementary to it. In any case, due to the housing of the clutch 21 in the support structure 5 of the module 1, which is shaped in a complementary manner to the clutch 21 on the side facing the latter, no additional axial dimensions are created.

The tubular appendage 15 (figure 8) has a substantially C- shaped section open towards the housing 38 so as to define an annular seat 39 communicating with the latter. The seat 39 houses a hydraulic actuator 41 for control of the clutch 21. Expediently, the support structure 5 defines an internal channel 44 for the supply/discharge of oil from the chamber 39 of the actuator 41; the channel 44 establishes communication between the chamber 39 and a radial fitting 45 arranged on the perimeter flange 9 of the support structure 5 and adapted to be connected with a hydraulic control circuit. In this way, additional dimensions are avoided, in particular axial dimensions, for the actuator 41 and the relative control circuit. The internal channel is expediently defined by two or more holes that can be made from the outside by means of conventional boring operations and intersecting with each other so as to define a continuous path between the fitting 45 and the chamber 39; the inlets of the holes can be closed by plugs, where necessary.

The clutch 21, described here summarily insofar as necessary for understanding of the present invention but not forming part of the invention, essentially comprises a first disc 46 adapted to be fixed to the crankshaft 7 and a second disc 47 connected in an angularly integral but axially free manner to a shaft 48 of the damper 22, with axis A, by means of a splined coupling 59 (fig. 8) .

More precisely, as can be clearly seen in figure 7, the first disc 46 of the clutch 21 is provided with a series of holes 43 for fastening to an end flange 61 of the crankshaft 7 by means of a corresponding series of screws 62 (fig. 9) provided with respective heads 63.

Between the discs 46 and 47 of the clutch 21 one or more friction discs 49 are interposed. The clutch 21 is kept normally closed by elastic means not illustrated and rotationally connects the shaft 48 of the damper 22 to the crankshaft 7 in the absence of operation of the actuator 41; when the actuator 41 is hydraulically operated, it opposes the elastic closing force, so as to separate the second disc 47 from the first disc 46. Between the actuator 41 ( rotationally fixed) and the second disc 47 (rotating) a bearing 42 is interposed which allows the transmission of axial loads and the relative rotation.

The damper 22 is illustrated in greater detail in figures 12, 13 and 14, and comprises an actuator 51 provided with a disc 54 connected rigidly (and preferably integrally) to the shaft 48, and provided with two radial spokes 53. The actuator 51 is supported on the tubular appendage 15 by a bearing 50.

The damper 22 further comprises an annular casing 55 formed of a half-shell 56 housed inside the first pulley 20 and of the latter .

The casing 55 delimits an annular chamber 57 divided by diametrically opposite internal lugs 58 of the half-shell 56 and of the first pulley 20 in two substantially semicircular housings, inside which respective arched springs 60 are arranged. The spokes 53 of the disc 52 of the actuator 51 run inside the annular chamber 57 and are comprised between respective ends of the springs 60, which stop against the lugs 58 so as to rotationally couple in an elastic manner the first pulley 20 to the actuator 51, and therefore to the second disc 47 of the clutch 21 rotationally integral with the shaft 48 of the actuator 51.

The half-shell 56 and the pulley 20, integral with each other by press-fitting and/or welding, are supported in a revolving manner with respect to the disc 52 of the actuator 51 by means of a pair of rings 59 having the function of plain bearings ( figure 12 ) .

Expediently, the second disc 47 of the clutch 21 and the disc 52 of the actuator 51 of the damper 22 are provided with corresponding series of holes 64, 65 having position corresponding to that of the holes 43 and diameter sufficient to allow passage of the heads 63 of the screws 62 for fastening the first disc 46 to the flange 61 of the crankshaft

7.

A flex plate 66 is fixed to the disc 52 of the actuator 51 constituting the interface member between the module 1 and the transmission T.

In particular, the flex plate 66 is connected to the disc 52 by means of a plurality of rivets 67 in the vicinity of an inner edge thereof, and is adapted to be connected to a torque converter of the transmission T (not illustrated) at an outer edge thereof. The flex plate 66 is able to compensate slight relative axial displacements between the module 1 and the transmission T.

The actuator 51, in addition to providing the kinematic functions described, has a crucial role in the relative centring of the elements of the hybrid drive unit H and therefore in facilitating the assembly operations.

In particular, with reference to figures 13 and 14, the shaft 48 has at an end thereof a cylindrical centring nose 67 adapted to couple slidingly with a centring hole of the crankshaft 7; at an opposite end, the actuator 51 has a blind axial hole 68 adapted to couple with a corresponding centring nose (not illustrated) of the torque converter.

The actuator 51 further defines the seat 69 for the bearing 50 (and therefore the centring with respect to the support structure 5) and circular lug 70 for centring the flex plate 66.

With reference to figures 9 and 10, the electric machine 2 is provided with a casing 71 and a rotor (not illustrated) to which a splined shaft 72 is connected. The latter slidingly engages a splined inner portion 73 of the shaft 25, so as to accomplish with it an angular but axially free coupling.

With reference to figures 9 and 11, the compressor 3 is provided with a casing 73 and a rotor (not illustrated) to which a splined shaft 74 is connected. The latter slidingly engages an internally splined sleeve 75 rigidly connected to the shaft 26, so as to accomplish with said sleeve an angular but axially free coupling.

As described previously, the connection of the module 1 to the clutch 21, to the electric machine 2 and to the compressor 3 is made by simple axial coupling of the relative rotating members with respective members of the module 1 appropriately configured (shaft 48, shaft 25, sleeve 75) . Said members therefore constitute real "power ports" of the module 1, to which the units complementary to the module can be connected extremely easily and with which they can exchange mechanical power .

This considerably facilitates the assembly operations, since the electric machine 2 and the compressor 3 can be connected to the module 1 before or after fixing of the latter to the engine E; alternatively, the electric machine 2 and the compressor 3 could be fixed directly to the engine E.

Analogously, the clutch 21 can be fixed to the module 1 prior to assembly of the latter on the engine or can be fixed on the engine prior to assembly of the module 1, during which the shaft 48 is coupled to the clutch 21.

The operation of the transmission module 1, already partly evident from the previous description, is the following.

When the clutch 21 is closed, the actuator 51 is connected both to the internal combustion engine (E) and to the electric machine 2 by means of the damper 22, known per se, and the transmission 6, in addition to the vehicle transmission T by means of the flex plate 66.

In this condition, the electric machine 2 can be used both as a generator (for recharging the battery with the internal combustion engine on, or as regenerative brake) and as a motor for starting the internal combustion engine or for delivery of an additional torque with the internal combustion engine on (boosting) .

When the clutch 21 is open, the electric motor can be used for electric drive, electric braking and coasting with the internal combustion engine off.

From an examination of the characteristics of the module 1 produced according to the present invention, the advantages it offers are evident.

In particular, the use of a module provided with a tray-like support structure with housings for the decoupling clutch and the respective actuator, with axial coupling "power ports" for connection of the module to the decoupling clutch, to the electric machine and to one or more auxiliaries and a preassembled transmission, facilitates installation of the module 1 on the engine E.

Due to the axial interpenetration between the coupling clutch 21 and the module 1, and the incorporation of the seat for the clutch actuator and the relative channels in the support structure 5, additional axial dimensions typical of the known solutions are avoided.

Figure 15 illustrates an embodiment variation of the module 1, indicated overall by the number 101, and described below in the aspects in which it differs from the module 1.

Elements that are different but corresponding to those already described with reference to the module 1 are indicated by the same reference numbers, increased by 100; the same reference numbers are used to indicate parts identical to parts already described .

In the module 101, the belt transmission 6 is replaced by a chain transmission 106. Furthermore, the module 101 is without compressor which can, for example, be arranged on the side of the engine opposite the transmission and driven by an accessories transmission of conventional type.

The transmission 106 comprises a crown 120 with axis A associated with the damper 22, and a pinion 123 with axis B adapted to be connected to the electric machine 2 by means of a shaft 25 supported in the support structure 5 as described.

The transmission 106 comprises a transmission chain 129, which is wound around the crown 120 and the pinion 123, and rotationally connects them to each other.

The transmission 106 lastly comprises a shoe tensioner 130, of known type, cooperating slidingly with the transmission chain 129 throughout the section between the pinion 123 and the crown 120, with reference to the feed direction of the chain 129, to ensure correct engagement with the pinion 123 and the crown 120.

The chain transmission operates expediently in an oil bath, and therefore must be provided with means for supply of lubrication oil inside the support structure 5 of the module (of conventional type and not illustrated) .

Otherwise, the structure and operation of the module 101 are identical to those of the module 1.

Lastly it is clear that modifications and variations can be made to the modules 1, 101 described that do not depart from the protective scope defined by the claims. In particular, the power ports can be made in another way, on condition they allow rotational coupling of the complementary members by means of simple axial insertion. Furthermore, the transmission 6 or 16 can be replaced by a gear transmission comprising a first gear wheel associated with the damper 22, a gear wheel integral with the shaft 25, and an intermediate gear wheel to transmit the motion from the first to the second gear wheel. Also in this case means for lubrication of the transmission must be provided.