ITRM20100253A1 - DOUBLE CLUTCH CHANGE - Google Patents

Description

DESCRIPTION

of the patent for industrial invention entitled:

"DOUBLE CLUTCH TRANSMISSION"

TECHNIQUE SECTOR

The present invention relates to a double clutch gearbox.

ANTERIOR ART

Patent application EP2008425750 describes a double clutch gearbox comprising: two primary shafts; a secondary tree; a plurality of pairs of gears, each of which mechanically couples a primary shaft to the secondary shaft, defines a respective gear and includes a primary gear mounted on the primary shaft and a secondary gear which is mounted on the secondary shaft and permanently meshes with the secondary shaft. primary gear itself; a plurality of synchronizers, each of which is mounted coaxially to a shaft, is coupled to a gear of at least one pair of gears, and is adapted to be actuated to engage the gear on the shaft; a plurality of forks, which actuate the synchronizers, are mounted movably, and are provided with corresponding nibs; a single drive shaft mounted rotatably about a longitudinal axis and axially sliding along the longitudinal axis itself; and a single gear actuator connected to the drive shaft for rotating the drive shaft about the longitudinal axis and for axially moving the drive shaft along the longitudinal axis. The drive shaft supports only one finger which is adapted to engage one nib at a time to impart a displacement to the corresponding fork; moreover, the nibs are arranged aligned parallel to the longitudinal axis of the drive shaft and are spaced apart by a distance greater than the size of the finger in such a way as to allow the finger to pass between two side-by-side nibs.

The double clutch gearbox described in patent application EP2008425750 has numerous advantages, as it is simple, economical and compact and requires the use of a single gear actuator which is capable of efficiently and effectively actuating all the forks. However, in the double clutch gearbox described in patent application EP2008425750 the finger carried by the drive shaft must make relatively long and articulated trajectories to move between two forks and consequently the time required to move the finger carried by the drive shaft between two forks is long enough.

DESCRIPTION OF THE INVENTION

The object of the present invention is to provide a double-clutch gearbox, which is free of the drawbacks described above and, in particular, is easy and inexpensive to manufacture and is light, compact and reliable.

According to the present invention, a double clutch gearbox is provided as claimed in the attached claims.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will now be described with reference to the attached drawings, which illustrate a non-limiting example of embodiment, in which:

Figure 1 is a schematic view with parts removed for clarity of a double clutch gearbox made in accordance with the present invention;

Figure 2 is a perspective view, schematic, and with parts removed for clarity of a fork of a synchronizer of the double clutch gearbox of figure 1;

Figure 3 is a plan view, schematic and with the removal of details for clarity of a series of plates provided with respective fingers of the double clutch gearbox of figure 1; And

• figures 4-8 are perspective views, schematic and with the removal of details for clarity of some movements performed by a movable fork of the double clutch gearbox of figure 1 to engage two different gears in succession.

PREFERRED EMBODIMENTS OF THE INVENTION

In Figure 1, the number 1 indicates as a whole an automatic manual transmission for a vehicle (not shown) propelled by an internal combustion engine 2, which is provided with a drive shaft 3.

The automatic manual transmission 1 comprises a power-assisted double clutch gearbox 4, which is provided with a pair of coaxial primary shafts 5, independent and inserted one inside the other. Furthermore, the double-clutch gearbox 4 comprises two coaxial clutches 6 arranged in parallel, each of which is adapted to connect a respective primary shaft 5 to the drive shaft 3 of the internal combustion engine 2. The double clutch gearbox 4 comprises a single secondary shaft 7 connected to a differential (not shown) which transmits motion to the driving wheels (not shown).

The dual clutch gearbox 4 illustrated in the attached figure has six forward gears indicated with Roman numerals (first gear I, second gear II, third gear III, fourth gear IV, fifth gear V and sixth gear VI) and a reverse gear (indicated with the letter R). Each primary shaft 5 and the secondary shaft 7 are mechanically coupled to each other by means of a plurality of gear pairs, each of which defines a respective gear and comprises a primary gear 8 mounted on the primary shaft 5 and a secondary gear 9 mounted on the secondary shaft 7. To allow correct operation of the double clutch gearbox 4, all the odd gears (first gear I, third gear III, fifth gear V) are coupled to the same primary 5th gear, while all the even gears (second gear II, fourth gear IV, and sixth gear VI) are coupled to the other primary shaft 5b.

Each primary gear 8 is keyed to a respective primary shaft 5 to rotate always integrally with the primary shaft 5 itself and meshes permanently with the respective secondary gear 9; instead, each secondary gear 9 is idle mounted on the secondary shaft 7. Furthermore, the double clutch gearbox 4 comprises four synchronizers 10, each of which is mounted coaxially to the secondary shaft 7, is arranged between two secondary gears 9 (with the exception of the synchronizer 10 of the fifth gear V which is arranged alongside a single secondary gear 9), and is adapted to be actuated to alternatively engage the two respective secondary gears 9 to the secondary shaft 7 (ie to alternatively make the two respective secondary gears 9 angularly integral with the secondary shaft 7). In other words, each synchronizer 10 comprises a guide sleeve which can be moved in one direction to engage a secondary gear 9 to the secondary shaft 7, or it can be moved in the other direction to engage the other secondary gear 9 to the shaft. 7 secondary (with the exception of the synchronizer 10 of the fifth gear V which engages a single secondary gear 9 to the secondary shaft 7).

Each synchronizer 10 is arranged between two secondary gears 9 (with the exception of the synchronizer 10 of the fifth gear V which is arranged alongside a single secondary gear 9) and is actuated by a respective fork 11 which moves axially along the shaft 7 in the two directions to move the guide sleeve of the synchronizer 10 between two engagement positions, in each of which the synchronizer 10 engages a respective secondary gear 9, and an intermediate neutral position, in which the synchronizer 10 engages none of the two secondary gears 9 (as previously mentioned, the synchronizer 10 of the fifth gear V has only one engagement position). Furthermore, each fork 11 is actuated by a fork 12 (better illustrated in Figure 2) which has a "V" shape (or an equivalent "U" shape) and is moved by a drive shaft 13 of a single actuator 14 common gears; the gear actuator 14 gives the control shaft 13 an axial translation movement (ie parallel to a central axis 15 of the control shaft 13) and a rotation movement about the central axis 15 of the control shaft 13. It is important to note that the control shaft 13 is provided with a single fork 12 which controls all the forks 11; this constructive solution allows to simplify both the construction and the control of the double clutch gearbox 4.

The 14-speed actuator can be electric for example of the type described in patent application EP2116745A1 incorporated herein by reference, or the 14-speed actuator can be hydraulic.

As illustrated in Figure 2, each fork 11 is carried by a rod 16, which is mounted axially sliding in a direction perpendicular to the central axis 15 of the control shaft 13 to allow the fork 11 itself to move axially along the 7 secondary shaft in both directions. A plate 17 is integral with each rod 16 which supports a finger 18 which can be engaged by the fork 12 to push the plate 17, and therefore the rod 16, axially in both directions. From figure 2, it is evident that the axial translation movement along the central axis 15 of the control shaft 13 allows to align the fork 12 with a specific finger 18 and therefore allows to choose the range of the gears, while the rotation movement around the central axis 15 of the control shaft 13 it allows to move a corresponding fork 11 and therefore allows to engage or disengage a gear of the currently selected range.

A retaining device 19 is associated with each fork 11, which is for example mechanically coupled to the rod 16, is made with the known spring-ball architecture, and is adapted to keep the fork 11 in its current position with a constant retaining force and predetermined. The function of each retaining device 19 is to keep the fork 11 in the current position avoiding random, uncontrolled and undesired movements of the fork 11 itself; obviously, according to the methods described below, the control shaft 13 is capable of applying to each fork 11 a driving force sufficiently higher than the retaining force generated by the respective retaining device 19 to ensure the desired displacement of the fork 11 itself.

As illustrated in Figure 3, the four fingers 18 are arranged aligned parallel to the central axis 15 of the control shaft 13 and are preferably equally spaced between them in such a way as to allow the fork 12 to engage only one finger 18 at a time (i.e. to align with only one finger 18 at a time so that the rotation of the fork 12 causes the fork 12 to push on only one finger 18 at a time).

The servo-assisted transmission 1 comprises a control unit 20 (schematically illustrated in Figure 1), which drives the 14-speed actuator to engage / disengage the gears and drives the clutch actuators (not shown) which control the opening and closing of the gears. two clutches 6.

The operation of the double clutch gearbox 4 is described below with reference to Figures 4-7; in particular, the method of engagement of the first gear I (Figures 4-5) starting from a neutral condition and the subsequent method of engagement of the second gear II (Figures 6-8) are described.

Figure 4 illustrates a neutral condition, in which no gear is engaged and the two clutches 6 are open (i.e. the drive shaft 3 is disconnected from both primary shafts 5). To engage the first gear I it is necessary to move the fork 11 which is connected to the finger 18a carried by the plate 17a and controls the synchronizer 10a adapted to engage the first gear I and the third gear III. The 14-speed actuator axially translates the control shaft 13 along the axis 15 so as to bring the fork 12 to align with the finger 18a as shown in Figure 4. Once the fork 12 is aligned with the finger 18a, the 14-speed actuator rotates the control shaft 13 (and therefore the fork 12 integral with the control shaft 13) around the axis 15 to push the finger 18a (therefore the plate 17a, the fork 11a and the synchronizer 10a) in the direction necessary to engage the first gear I as illustrated in Figure 5; if it had been necessary to engage third gear III (or disengage first gear I), then the 14-speed actuator would have rotated the control shaft 13 (hence the fork 12) in the opposite direction. As previously said, in moving the finger 18a (hence the plate 17a, the fork 11a and the synchronizer 10a) the 14-speed actuator must overcome the retaining torque generated by the corresponding retaining device 19.

Once the first gear I has been engaged in the manner described above, the clutch 6a can be closed to transmit the motion from the drive shaft 3 to the driving wheels (not shown) with the transmission ratio of the first gear I. Furthermore, once engaged in the in the manner described above, the first gear I, the 14-speed actuator can also engage the second gear II by moving the finger 18c the plate 17c (therefore the plate 17c, the fork 11le and the synchronizer 10c).

To engage the second gear II, the gear actuator 14 rotates the control shaft 13 without performing any axial translation so as to cause the fork 12 to disengage the finger 18a as illustrated in Figure 6; this operation does not involve the disengagement of the first gear I thanks to the retaining torque exerted by the retaining device 19 which prevents the plate 17a (hence the fork 11a and the synchronizer 10a) from moving except under the thrust of the 14-speed actuator. Once the fork 12 has been disengaged from the finger 18a, the 14-speed actuator axially translates the drive shaft 13 to align the fork 12 with the finger 18c as shown in Figure 7. Once the fork 12 of the shaft 13 control shaft is aligned with the finger 18c, the 14-speed actuator rotates the control shaft 13 around the axis 15 to translate the finger 18c (therefore the plate 17c, the fork 11le, and the synchronizer 10c) in the direction necessary to engage second gear II as illustrated in Figure 8; if it had been necessary to engage fourth gear IV (or disengage second gear II), then the 14-speed actuator would have rotated the control shaft 13 (hence the fork 12) in the opposite direction. As previously stated, in rotating the plate 17c, the gear actuator 14 must overcome the retaining torque generated by the corresponding retaining device 19.

Once the second gear II has been engaged in the manner described above, the clutch 6b can be closed and at the same time the clutch 6a must be opened to transmit the motion from the drive shaft 3 to the driving wheels (not shown) with the transmission ratio of the second gear II. Furthermore, once the second gear II has been engaged in the manner described above, the 14-speed actuator acts to disengage the first gear I and therefore engage the third gear III by rotating the finger 18a (therefore the plate 17a, the fork 11a, and the synchronizer 10a) and so on.

According to a possible embodiment, in waiting conditions, if there is a gear that transmits the motion, the fork 12 is placed (i.e. placed in contact) on the finger 18 corresponding to the gear that transmits the motion to prevent accidental and involuntary disengagement of the gear. itself. In other words, once the fork 12 has been moved to engage the current gear which transmits the motion and to engage the next gear (determined by a prediction algorithm), the fork 12 itself is placed on the finger 18 corresponding to the gear which it transmits the motion so as to prevent an accidental and involuntary movement of the finger 18 which would cause an accidental and involuntary disengagement of the gear itself.

The dual clutch 4 gearbox described above has numerous advantages, as it is simple, economical and compact and requires the use of a single 14-speed actuator which is capable of efficiently and effectively actuating all 11 forks. fork 12 carried by the control shaft 13 can be moved between two different fingers 18, following only a rectilinear trajectory which constitutes the shortest possible path between the two fingers 18 themselves; in this way, the time required to move the fork 12 carried by the drive shaft 13 between two fingers 18 is reduced to the indispensable minimum.

Claims (5)

CLAIMS 1) Double clutch gearbox (4) comprising: two primary trees (5); at least one secondary shaft (7); a plurality of pairs of gears (8, 9), each of which mechanically couples a primary shaft (5) to the secondary shaft (7), defines a respective gear and comprises a primary gear (8) mounted on the shaft (5) primary and a secondary gear (9) which is mounted on the secondary shaft (7) and permanently meshes with the primary gear (8) itself; a plurality of synchronizers (10), each of which is mounted coaxially to a shaft (5; 7), is coupled to a gear (10; 11) of at least one pair of gears, and is adapted to be actuated to engage the gear (10; 11) to the shaft (5; 7); a plurality of forks (11), which actuate the synchronizers (10) and are mounted movably; a single drive shaft (13) mounted rotatably about a central axis (15) and axially sliding along the central axis (15) itself; and a single gear actuator (14) connected to the control shaft (13) to rotate the control shaft (13) around the central axis (15) and to axially move the control shaft (13) along the axis (15) central; the double clutch gearbox (4) is characterized by the fact that: each fork (11) is provided with its own finger (18) which protrudes from a plate (17) integral with the fork (11) itself; And the control shaft (13) supports a single fork (12) which has a "V" shape and is able to engage one finger (18) at a time to impart a displacement to the corresponding fork (11). 2) Double clutch gearbox (4) according to claim 1 in which the fingers (18) are arranged aligned parallel to the central axis (15) of the control shaft (13). 3) Double clutch gearbox (4) according to claim 1 or 2 and comprising for each fork (11) a corresponding retaining device (19), which is able to keep the fork (11) in the current position with a force of constant and predetermined retention; the control shaft (13) is capable of applying to each fork (11) a driving force sufficiently higher than the retaining force generated by the respective retaining device (19) to ensure the desired displacement of the fork (11) itself. 4) Double clutch gearbox (4) according to one of claims 1 to 3, in which each fork (11) is carried by a rod (16), which is mounted axially sliding and supports the corresponding plate (17) carrying the finger (18). 5) Double clutch gearbox (4) according to one of claims 1 to 4, in which in waiting conditions, if there is a gear that transmits the motion, the fork (12) is placed on the finger (18) corresponding to the gear it transmits motion to prevent accidental and involuntary disengagement of the gear itself.