WO2007031563A1 - Motor vehicle automatic transmission and relative actuating method - Google Patents

Motor vehicle automatic transmission and relative actuating method Download PDF

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Publication number
WO2007031563A1
WO2007031563A1 PCT/EP2006/066379 EP2006066379W WO2007031563A1 WO 2007031563 A1 WO2007031563 A1 WO 2007031563A1 EP 2006066379 W EP2006066379 W EP 2006066379W WO 2007031563 A1 WO2007031563 A1 WO 2007031563A1
Authority
WO
WIPO (PCT)
Prior art keywords
sleeve
automatic transmission
gear
shaft
lock
Prior art date
Application number
PCT/EP2006/066379
Other languages
French (fr)
Other versions
WO2007031563A8 (en
Inventor
Martin Berger
Alberto Giacometti
Klaus Kalmbach
Peter Werth
Fulvio Lo Conte
Original Assignee
Ferrari S.P.A.
Hofer-Pdc-Gmbh
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Ferrari S.P.A., Hofer-Pdc-Gmbh filed Critical Ferrari S.P.A.
Publication of WO2007031563A1 publication Critical patent/WO2007031563A1/en
Publication of WO2007031563A8 publication Critical patent/WO2007031563A8/en

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Classifications

    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16D—COUPLINGS FOR TRANSMITTING ROTATION; CLUTCHES; BRAKES
    • F16D23/00—Details of mechanically-actuated clutches not specific for one distinct type
    • F16D23/02—Arrangements for synchronisation, also for power-operated clutches
    • F16D23/04—Arrangements for synchronisation, also for power-operated clutches with an additional friction clutch
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16H—GEARING
    • F16H61/00—Control functions within control units of change-speed- or reversing-gearings for conveying rotary motion ; Control of exclusively fluid gearing, friction gearing, gearings with endless flexible members or other particular types of gearing
    • F16H61/26—Generation or transmission of movements for final actuating mechanisms
    • F16H61/28—Generation or transmission of movements for final actuating mechanisms with at least one movement of the final actuating mechanism being caused by a non-mechanical force, e.g. power-assisted
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16D—COUPLINGS FOR TRANSMITTING ROTATION; CLUTCHES; BRAKES
    • F16D23/00—Details of mechanically-actuated clutches not specific for one distinct type
    • F16D23/02—Arrangements for synchronisation, also for power-operated clutches
    • F16D23/04—Arrangements for synchronisation, also for power-operated clutches with an additional friction clutch
    • F16D23/06—Arrangements for synchronisation, also for power-operated clutches with an additional friction clutch and a blocking mechanism preventing the engagement of the main clutch prior to synchronisation
    • F16D2023/0656—Details of the tooth structure; Arrangements of teeth
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16H—GEARING
    • F16H61/00—Control functions within control units of change-speed- or reversing-gearings for conveying rotary motion ; Control of exclusively fluid gearing, friction gearing, gearings with endless flexible members or other particular types of gearing
    • F16H61/26—Generation or transmission of movements for final actuating mechanisms
    • F16H61/28—Generation or transmission of movements for final actuating mechanisms with at least one movement of the final actuating mechanism being caused by a non-mechanical force, e.g. power-assisted
    • F16H2061/2823—Controlling actuator force way characteristic, i.e. controlling force or movement depending on the actuator position, e.g. for adapting force to synchronisation and engagement of gear clutch
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16H—GEARING
    • F16H3/00—Toothed gearings for conveying rotary motion with variable gear ratio or for reversing rotary motion
    • F16H3/02—Toothed gearings for conveying rotary motion with variable gear ratio or for reversing rotary motion without gears having orbital motion
    • F16H3/08—Toothed gearings for conveying rotary motion with variable gear ratio or for reversing rotary motion without gears having orbital motion exclusively or essentially with continuously meshing gears, that can be disengaged from their shafts
    • F16H3/087—Toothed gearings for conveying rotary motion with variable gear ratio or for reversing rotary motion without gears having orbital motion exclusively or essentially with continuously meshing gears, that can be disengaged from their shafts characterised by the disposition of the gears
    • F16H3/089—Toothed gearings for conveying rotary motion with variable gear ratio or for reversing rotary motion without gears having orbital motion exclusively or essentially with continuously meshing gears, that can be disengaged from their shafts characterised by the disposition of the gears all of the meshing gears being supported by a pair of parallel shafts, one being the input shaft and the other the output shaft, there being no countershaft involved
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16H—GEARING
    • F16H59/00—Control inputs to control units of change-speed-, or reversing-gearings for conveying rotary motion
    • F16H59/36—Inputs being a function of speed
    • F16H59/46—Inputs being a function of speed dependent on a comparison between speeds

Definitions

  • the present invention relates to a motor vehicle automatic transmission.
  • An automatic car transmission comprising, for example, an input shaft, which is connected to a propeller shaft of the vehicle and supports a number of first gears fitted in angularly fixed manner to the input shaft; and an output shaft, which is parallel to the input shaft, is connected to a differential to transmit power to the drive wheels of the vehicle, and supports a number of second gears, each meshing with a relative first gear with a given gear ratio corresponding to a given vehicle gear.
  • Each second gear is fitted in rotary manner to the output shaft, and is locked angularly to the output shaft by a synchronizing device normally shared by two second gears .
  • the synchronizing device comprises an annular main body fitted in angularly fixed manner to the output shaft; and a sleeve extending about the main body and fitted in angularly fixed, axially sliding manner to the main body by a number of teeth formed on its inner surface and which mesh with relative teeth formed on the outer surface of the main body.
  • the sleeve is normally maintained in a rest position, in which the sleeve is connected in angularly fixed manner to the main body only, by a lock device, and is movable axially by an actuating device between the rest position and two work positions, in each of which the sleeve is connected in angularly fixed manner to both the main body and a relative second gear.
  • the lock device comprises a number of pins, which extend radially outwards from the main body, support respective push blocks locked radially between the main body and the sleeve, and are normally maintained in a lock position, in which the pins engage respective seats on the inner surface of the sleeve, by respective push springs interposed between the main body and the pins.
  • the synchronizing device also comprises a synchronizing ring, which is fitted in axially sliding manner to the sleeve, is rotated by the sleeve by means of a splined coupling with a given tangential clearance, is located between the main body and a coupling gear projecting axially from the relative second gear, has a number of teeth on its outer surface, and is bounded internally by a substantially truncated- cone-shaped surface.
  • the push blocks When the sleeve is moved axially from the rest position to one of the work positions, the push blocks first come into contact with the relative synchronizing ring and then push it along a central, substantially truncated-cone-shaped shank projecting axially from the relative coupling gear.
  • the sleeve, synchronizing ring, and coupling gear teeth are so shaped that, only when the rotation speeds of the coupling gear and sleeve are equal, can the sleeve move axially forward to first disengage the pins, then move forward between the synchronizing ring teeth, and finally engage the coupling gear of the second gear to engage the relative vehicle gear.
  • a motor vehicle automatic transmission as claimed in Claims 1 to 11.
  • the present invention also relates to a method of actuating a motor vehicle automatic transmission.
  • Figure 1 shows, schematically, a preferred embodiment of the automatic transmission according to the present invention
  • Figure 2 shows a schematic longitudinal section, with parts removed for clarity, of a detail of the Figure 1 automatic transmission
  • Figure 3 shows a schematic detail of Figure 2 ;
  • Figure 4 shows a rotation speed graph of certain component parts of the Figure 1 automatic transmission.
  • Number 1 in Figure 1 indicates as a whole an automatic transmission for a vehicle (not shown) and comprising, in the example shown, an input shaft 2, which is mounted to rotate about a longitudinal axis 3, is connected by two bevel gears 4 to a propeller shaft 5, in turn connected to a drive shaft (not shown) of the vehicle (not shown) by a clutch (not shown) , and supports a number of (in the example shown, four) annular gears 6 fitted in angularly fixed manner to shaft 2.
  • Transmission 1 also comprises an output shaft 7 mounted to rotate about a longitudinal axis 8, parallel to axis 3, and supporting a number of annular gears 9, which are equal in number to gears 6, are fitted in rotary manner to shaft 7, and each of which meshes with a relative gear 6 with a given gear ratio corresponding to a given gear of the vehicle (not shown) .
  • Shaft 7 also supports an annular gear 10 fitted in angularly fixed manner to shaft 7 and meshing with an annular gear 11 of a differential 12 for transmitting power to two axle shafts (not shown) , each integral with a respective drive wheel (not shown) of the vehicle (not shown) .
  • Gears 9 are selectively locked angularly to shaft 7 by a number of (in the example shown, two) synchronizing devices 13, each shared by two respective gears 9.
  • each device 13 comprises a substantially annular main body 14 fitted to shaft 7 coaxially with axis 8 and in angularly and axially fixed manner, and extending between the two relative gears 9.
  • Device 13 also comprises a sleeve 15, which extends about body 14, coaxially with axis 8, has an annular groove 16 formed on its outer surface, and is connected in angularly fixed, axially sliding manner to body 14 by a number of teeth 17 formed on the inner surface of sleeve 15 and which mesh with corresponding teeth (not shown) formed on the outer surface of body 14.
  • Sleeve 15 is normally maintained in a rest position - in which teeth 17 mesh solely with the teeth (not shown) on body 14 - by a lock device 18 comprising a number of lock balls 19 (only one shown in Figure 2), which are equally spaced about axis 8 and project radially outwards from body 14 to normally engage pushed by respective springs 20 interposed between body 14 and balls 19 - respective seats 21 formed on the inner surface of sleeve 15.
  • a lock device 18 comprising a number of lock balls 19 (only one shown in Figure 2), which are equally spaced about axis 8 and project radially outwards from body 14 to normally engage pushed by respective springs 20 interposed between body 14 and balls 19 - respective seats 21 formed on the inner surface of sleeve 15.
  • Each ball 19 is associated with a push block 22, which extends about ball 19, is locked radially between body 14 and sleeve 15, and is movable axially, as explained in detail below, in a direction 23 parallel to axis 8.
  • lock device 18 is replaced by a hydraulic, pneumatic, or electromagnetic lock device .
  • Device 13 also comprises two synchronizing rings 24 located on opposite sides of body 14 in direction 23, and each associated with a respective gear 9.
  • Each ring 24 is bounded externally by a smooth cylindrical surface 25 substantially coaxial with axis 8, is therefore a toothless ring, has an outside diameter approximately equal to but no larger than the inside diameter of sleeve 15, and is bounded internally by a substantially truncated-cone-shaped surface 26.
  • Each ring 24 is fitted in angularly fixed, axially sliding manner to sleeve 15, and in sliding manner to a respective coupling gear 27, which is connected in angularly and axially fixed manner to a corresponding gear 9, has a number of teeth 28 formed on its outer surface, and has a central, substantially truncated-cone- shaped shank 29 engaging relative ring 24.
  • Device 13 also has a control unit 30 comprising three sensors 31, 32, 33 for continuously determining the rotation speeds of sleeve 15 and the two gears 9, respectively, about axis 8; and an electronic central control unit 34, which compares the rotation speeds of sleeve 15 and the gear 9 corresponding to the vehicle gear to be engaged, and commands operation of an actuating device 35, engaging groove 16, to move sleeve 15 axially in direction 23.
  • a control unit 30 comprising three sensors 31, 32, 33 for continuously determining the rotation speeds of sleeve 15 and the two gears 9, respectively, about axis 8; and an electronic central control unit 34, which compares the rotation speeds of sleeve 15 and the gear 9 corresponding to the vehicle gear to be engaged, and commands operation of an actuating device 35, engaging groove 16, to move sleeve 15 axially in direction 23.
  • springs 20 are calibrated to push respective balls 19 inside respective seats 21 with a force which, during the above operating sequence, is greater than the force exerted in the opposite direction on balls 19 by sleeve 15.
  • teeth 17 and 28 mesh with a given tangential clearance; each tooth 28 has a portion 28a which meshes with a corresponding portion 17a of at least one tooth 17; and each portion 17a, 28a is bounded laterally by two sides 17b, 28b, each of which slopes by an angle a. of less than 6°, and preferably of 0.5° to 3°, with respect to an axial reference plane P, to also permit disengagement of the vehicle gear under load.
  • Figure 4 shows a time graph of the rotation speed nl of sleeve 15 with respect to the rotation speed n2 of gear 9 corresponding to the vehicle gear to be engaged, and assuming speed nl of sleeve 15 in the rest position is greater than the constant speed n2 of gear 9. Shifting commences at an instant tl with release of the clutch (not shown) connecting the drive shaft (not shown) of the vehicle (not shown) to propeller shaft 5, and with a consequent fall in speed nl between instant tl, corresponding to the start of the synchronization phase, and an instant t2, corresponding to the end of the synchronization phase and release of balls 19 by sleeve 15.
  • speed nl continues to fall - though slower than between instants tl and t2 - between instant t2, at which the difference between speeds nl and n2 substantially equals a given threshold value, and an instant t3, at which speeds nl and n2 are substantially equal, and sleeve 15 is in the work position meshing with gear 27.
  • Transmission 1 also has several other advantages, foremost of which are : low-cost manufacture of rings 24; easier assembly of synchronizing devices 13; relatively fast shift, by virtue of teeth 17 of sleeve 15 meshing solely with teeth 28 of gears 27; and correct gear engagement, by virtue of constant monitoring of speeds nl and n2 by sensors 31, 32 and 33, and correct operation of actuating device 35 by central control unit 34.
  • ring 24 is replaced by at least two rings 24 with respective truncated-cone-shaped surfaces contacting each other.

Abstract

In a motor vehicle automatic transmission, a gear (9) is locked angularly to a shaft (7) of the transmission by a synchronizing device (13) having a sleeve (15) which is moved axially, by an actuating device (35) and along a toothless synchronizing ring (24), to and from a work position in which the sleeve (15) is connected in angularly fixed manner to both the shaft (7) of the transmission and the gear (9); and a control device (30) determines and compares the rotation speeds (n1, n2) of the sleeve (15) and the gear (9), and commands operation of the actuating device (35) of the sleeve (15) as a function of the difference between the rotation speeds (n1, n2).

Description

MOTOR VEHICLE AUTOMATIC TRANSMISSION AND RELATIVE ACTUATING METHOD
TECHNICAL FIELD
The present invention relates to a motor vehicle automatic transmission. BACKGROUND ART
An automatic car transmission is known comprising, for example, an input shaft, which is connected to a propeller shaft of the vehicle and supports a number of first gears fitted in angularly fixed manner to the input shaft; and an output shaft, which is parallel to the input shaft, is connected to a differential to transmit power to the drive wheels of the vehicle, and supports a number of second gears, each meshing with a relative first gear with a given gear ratio corresponding to a given vehicle gear.
Each second gear is fitted in rotary manner to the output shaft, and is locked angularly to the output shaft by a synchronizing device normally shared by two second gears .
The synchronizing device comprises an annular main body fitted in angularly fixed manner to the output shaft; and a sleeve extending about the main body and fitted in angularly fixed, axially sliding manner to the main body by a number of teeth formed on its inner surface and which mesh with relative teeth formed on the outer surface of the main body. The sleeve is normally maintained in a rest position, in which the sleeve is connected in angularly fixed manner to the main body only, by a lock device, and is movable axially by an actuating device between the rest position and two work positions, in each of which the sleeve is connected in angularly fixed manner to both the main body and a relative second gear.
The lock device comprises a number of pins, which extend radially outwards from the main body, support respective push blocks locked radially between the main body and the sleeve, and are normally maintained in a lock position, in which the pins engage respective seats on the inner surface of the sleeve, by respective push springs interposed between the main body and the pins.
For each second gear, the synchronizing device also comprises a synchronizing ring, which is fitted in axially sliding manner to the sleeve, is rotated by the sleeve by means of a splined coupling with a given tangential clearance, is located between the main body and a coupling gear projecting axially from the relative second gear, has a number of teeth on its outer surface, and is bounded internally by a substantially truncated- cone-shaped surface.
When the sleeve is moved axially from the rest position to one of the work positions, the push blocks first come into contact with the relative synchronizing ring and then push it along a central, substantially truncated-cone-shaped shank projecting axially from the relative coupling gear.
When the truncated-cone-shaped surface of the synchronizing ring contacts the truncated-cone-shaped shank of the coupling gear, braking action is exerted between the synchronizing ring and the coupling gear to eliminate the tangential clearance between the synchronizing ring and the sleeve. As a result, the teeth on the sleeve contact the teeth on the synchronizing ring to increase the axial contact pressure between the synchronizing ring and the coupling gear, and to synchronize the rotation speeds of the coupling gear (and hence the relative second gear) and the whole defined by the output shaft, the main body, the sleeve, and the synchronizing ring.
The sleeve, synchronizing ring, and coupling gear teeth are so shaped that, only when the rotation speeds of the coupling gear and sleeve are equal, can the sleeve move axially forward to first disengage the pins, then move forward between the synchronizing ring teeth, and finally engage the coupling gear of the second gear to engage the relative vehicle gear.
Known automatic transmissions of the above type have several drawbacks, mainly due to the fact that the synchronizing rings are relatively expensive to produce, make assembly of the synchronizing device fairly difficult, and involve relatively complex mechanical synchronization of the various component parts in rotation, thus resulting in relatively slow shift. DISCLOSURE OF INVENTION
It is an object of the present invention to provide a motor vehicle automatic transmission designed to eliminate the aforementioned drawbacks, and which is cheap and easy to produce.
According to the present invention, there is provided a motor vehicle automatic transmission as claimed in Claims 1 to 11. The present invention also relates to a method of actuating a motor vehicle automatic transmission.
According to the present invention, there is provided a method of actuating a motor vehicle automatic transmission, as claimed in Claims 12 to 14. BRIEF DESCRIPTION OF THE DRAWINGS
A non-limiting embodiment of the present invention will be described by way of example with reference to the accompanying drawings, in which:
Figure 1 shows, schematically, a preferred embodiment of the automatic transmission according to the present invention;
Figure 2 shows a schematic longitudinal section, with parts removed for clarity, of a detail of the Figure 1 automatic transmission;
Figure 3 shows a schematic detail of Figure 2 ; Figure 4 shows a rotation speed graph of certain component parts of the Figure 1 automatic transmission. BEST MODE FOR CARRYING OUT THE INVENTION
Number 1 in Figure 1 indicates as a whole an automatic transmission for a vehicle (not shown) and comprising, in the example shown, an input shaft 2, which is mounted to rotate about a longitudinal axis 3, is connected by two bevel gears 4 to a propeller shaft 5, in turn connected to a drive shaft (not shown) of the vehicle (not shown) by a clutch (not shown) , and supports a number of (in the example shown, four) annular gears 6 fitted in angularly fixed manner to shaft 2. Transmission 1 also comprises an output shaft 7 mounted to rotate about a longitudinal axis 8, parallel to axis 3, and supporting a number of annular gears 9, which are equal in number to gears 6, are fitted in rotary manner to shaft 7, and each of which meshes with a relative gear 6 with a given gear ratio corresponding to a given gear of the vehicle (not shown) .
Shaft 7 also supports an annular gear 10 fitted in angularly fixed manner to shaft 7 and meshing with an annular gear 11 of a differential 12 for transmitting power to two axle shafts (not shown) , each integral with a respective drive wheel (not shown) of the vehicle (not shown) .
Gears 9 are selectively locked angularly to shaft 7 by a number of (in the example shown, two) synchronizing devices 13, each shared by two respective gears 9.
As shown in Figure 2, each device 13 comprises a substantially annular main body 14 fitted to shaft 7 coaxially with axis 8 and in angularly and axially fixed manner, and extending between the two relative gears 9.
Device 13 also comprises a sleeve 15, which extends about body 14, coaxially with axis 8, has an annular groove 16 formed on its outer surface, and is connected in angularly fixed, axially sliding manner to body 14 by a number of teeth 17 formed on the inner surface of sleeve 15 and which mesh with corresponding teeth (not shown) formed on the outer surface of body 14.
Sleeve 15 is normally maintained in a rest position - in which teeth 17 mesh solely with the teeth (not shown) on body 14 - by a lock device 18 comprising a number of lock balls 19 (only one shown in Figure 2), which are equally spaced about axis 8 and project radially outwards from body 14 to normally engage pushed by respective springs 20 interposed between body 14 and balls 19 - respective seats 21 formed on the inner surface of sleeve 15.
Each ball 19 is associated with a push block 22, which extends about ball 19, is locked radially between body 14 and sleeve 15, and is movable axially, as explained in detail below, in a direction 23 parallel to axis 8.
In variations not shown, lock device 18 is replaced by a hydraulic, pneumatic, or electromagnetic lock device .
Device 13 also comprises two synchronizing rings 24 located on opposite sides of body 14 in direction 23, and each associated with a respective gear 9. Each ring 24 is bounded externally by a smooth cylindrical surface 25 substantially coaxial with axis 8, is therefore a toothless ring, has an outside diameter approximately equal to but no larger than the inside diameter of sleeve 15, and is bounded internally by a substantially truncated-cone-shaped surface 26.
Each ring 24 is fitted in angularly fixed, axially sliding manner to sleeve 15, and in sliding manner to a respective coupling gear 27, which is connected in angularly and axially fixed manner to a corresponding gear 9, has a number of teeth 28 formed on its outer surface, and has a central, substantially truncated-cone- shaped shank 29 engaging relative ring 24.
Device 13 also has a control unit 30 comprising three sensors 31, 32, 33 for continuously determining the rotation speeds of sleeve 15 and the two gears 9, respectively, about axis 8; and an electronic central control unit 34, which compares the rotation speeds of sleeve 15 and the gear 9 corresponding to the vehicle gear to be engaged, and commands operation of an actuating device 35, engaging groove 16, to move sleeve 15 axially in direction 23.
Operation of synchronizing device 13 will now be described with reference to Figures 2 and 3, assuming engagement of a given vehicle gear, assuming the rotation speeds of sleeve 15 and the gear 9 considered are determined continuously by sensor 31 and sensor 32 or 33 respectively, and commencing with sleeve 15 in the rest position .
When pushed by actuating device 35, sleeve 15 and, therefore, lock balls 19 and push blocks 22 are moved in direction 23 so as to first move blocks 22 into contact with the synchronizing ring 24 considered, then move ring 24 axially along shank 29 of relative coupling gear 27, and, finally, grip ring 24 on shank 29.
In this connection, it should be pointed out that springs 20 are calibrated to push respective balls 19 inside respective seats 21 with a force which, during the above operating sequence, is greater than the force exerted in the opposite direction on balls 19 by sleeve 15.
By virtue of the friction generated by gripping ring 24 on shank 29, the rotation speeds of sleeve 15 (and hence output shaft 7) and gear 27 (and hence gear 9) are gradually synchronized. And when the difference, calculated by central control unit 34 in response to the signals from sensors 31, 32 or 33, between the rotation speeds of sleeve 15 and gear 9 substantially equals a given threshold value, sleeve 15 is moved further in direction 23, so that less force is exerted on balls 19 by springs 20 than in the opposite direction by sleeve 15, thus enabling sleeve 15 to first disengage balls 19 and then move into a work position (not shown) in which teeth 17 of sleeve 15 mesh with both the teeth (not shown) of body 14 and the teeth 28 of gear 27 to make gear 9 angularly integral with shaft 7.
In connection with the above, it should be pointed out that, as shown in Figure 3, when sleeve 15 is in the work position: teeth 17 and 28 mesh with a given tangential clearance; each tooth 28 has a portion 28a which meshes with a corresponding portion 17a of at least one tooth 17; and each portion 17a, 28a is bounded laterally by two sides 17b, 28b, each of which slopes by an angle a. of less than 6°, and preferably of 0.5° to 3°, with respect to an axial reference plane P, to also permit disengagement of the vehicle gear under load.
Figure 4 shows a time graph of the rotation speed nl of sleeve 15 with respect to the rotation speed n2 of gear 9 corresponding to the vehicle gear to be engaged, and assuming speed nl of sleeve 15 in the rest position is greater than the constant speed n2 of gear 9. Shifting commences at an instant tl with release of the clutch (not shown) connecting the drive shaft (not shown) of the vehicle (not shown) to propeller shaft 5, and with a consequent fall in speed nl between instant tl, corresponding to the start of the synchronization phase, and an instant t2, corresponding to the end of the synchronization phase and release of balls 19 by sleeve 15.
Afterwards, speed nl continues to fall - though slower than between instants tl and t2 - between instant t2, at which the difference between speeds nl and n2 substantially equals a given threshold value, and an instant t3, at which speeds nl and n2 are substantially equal, and sleeve 15 is in the work position meshing with gear 27. In connection with the above, it should be pointed out that the absence of teeth on synchronizing ring 24 and the presence of control unit 30 enable release of balls 19 by sleeve 15 when the difference between speeds nl and n2 equals a given threshold value of other than zero, and also enable speed nl to be maintained above speed n2 at all times up to instant t3, at which sleeve 15 meshes with gear 27.
Transmission 1 also has several other advantages, foremost of which are : low-cost manufacture of rings 24; easier assembly of synchronizing devices 13; relatively fast shift, by virtue of teeth 17 of sleeve 15 meshing solely with teeth 28 of gears 27; and correct gear engagement, by virtue of constant monitoring of speeds nl and n2 by sensors 31, 32 and 33, and correct operation of actuating device 35 by central control unit 34.
In a variation not shown, to increase friction between ring 24 and gear 27, ring 24 is replaced by at least two rings 24 with respective truncated-cone-shaped surfaces contacting each other.

Claims

1) An automatic transmission for motor vehicles, comprising a first shaft (2); at least two first gears (6) fitted in angularly fixed manner to said first shaft
(2); a second shaft (7); at least two second gears (9), each of which meshes with a relative first gear (6) with a given gear ratio corresponding to a given gear of the vehicle, and is fitted in rotary manner to said second shaft (7); a coupling member (27) connected in angularly fixed manner to each said second gear (9); and at least one synchronizing unit (13) for angularly locking at least one said second gear (9) on the second shaft (7); the synchronizing unit (13) comprising a sleeve (15) fitted in sliding and angularly fixed manner to the second shaft (7); a lock device (18) for maintaining the sleeve (15) in a rest position wherein the sleeve (15) is connected in angularly fixed manner solely to the second shaft (7); an actuating device (35) for moving the sleeve (15) axially between said rest position and at least one work position wherein the sleeve (15) is connected in angularly fixed manner to the second shaft (7) and to the relative coupling member (27); and at least one synchronizing ring (24) fitted in angularly fixed and axially sliding manner to the second shaft (7) to synchronize the rotation speeds (nl, n2) of the sleeve (15) and the relative coupling member (27); and the automatic transmission being characterized in that the synchronizing ring (24) is a toothless ring; logic control means (30) determining and comparing the rotation speeds (nl, n2) of the sleeve (15) and the relative coupling member (27), and commanding operating of the actuating device (35) as a function of the difference between said rotation speeds (nl, n2).
2) An automatic transmission as claimed in Claim 1, wherein the synchronizing ring (24) is bounded internally by a first truncated-cone-shaped surface (26), and is fitted in sliding manner to a second truncated-cone- shaped surface (29) of the coupling member (27); push means (22) being provided to move the synchronizing ring (24) axially and to frictionally connect said first and said second truncated-cone-shaped surface (26, 29). 3) An automatic transmission as claimed in Claim 1 or 2, wherein the lock device (18) comprises at least one lock member (19); a seat (21) formed in said sleeve (15) to receive the lock member (19); and elastic push means (20) for normally maintaining the lock member (19) inside said seat (21) .
4) An automatic transmission as claimed in Claim 3, wherein the elastic push means (20) and the sleeve (15) exert on the lock member (19) a first and opposite second force respectively; the elastic push means (20) being calibrated so that the first force is less than the second force when the difference between said rotation speeds (nl, n2) substantially equals a given threshold value . 5) An automatic transmission as claimed in any one of the foregoing Claims, and also comprising at least one push block (22), which is fitted in axially sliding manner to said second shaft (7), and is pushed by said sleeve (15) into contact with the synchronizing ring (24) to grip the synchronizing ring (24) to the coupling member (27) .
6) An automatic transmission as claimed in Claim 1 or 2, wherein the lock device (18) comprises hydraulic lock means.
7) An automatic transmission as claimed in Claim 1 or 2, wherein the lock device (18) comprises pneumatic lock means.
8) An automatic transmission as claimed in Claim 1 or 2, wherein the lock device (18) comprises electromagnetic lock means.
9) An automatic transmission as claimed in any one of the foregoing Claims, wherein the sleeve (15) and the coupling members (27) each have a respective number of teeth (17, 28), each of which has a meshing portion (17a, 28a) which meshes with at least one tooth (17, 28) of another number of teeth (17, 28); the meshing portion (17a, 28a) being bounded laterally by two sides (17b, 28b) , each sloping at a given lock angle (a) with respect to an axial reference plane (P) .
10) An automatic transmission as claimed in Claim 9, wherein the lock angle (a) is less than 6°.
11) An automatic transmission as claimed in Claim 9, wherein the lock angle (a) ranges between 0.5° and 3°.
12) A method of actuating an automatic transmission as claimed in any one of the foregoing Claims, characterized by comprising the steps of: determining the rotation speeds (nl, n2) of the sleeve (15) and of the second gear (9) corresponding to the vehicle gear to be engaged; comparing said rotation speeds (nl, n2); and commanding operation of the actuating device (35) of the sleeve (15) as a function of the difference between said rotation speeds (nl, n2) .
13) A method as claimed in Claim 12, and also comprising the step of: releasing the sleeve (15) from the lock device (18) when the rotation speeds (nl, n2) differ.
14) A method as claimed in Claim 12 or 13, and also comprising the step of: eliminating the difference between said rotation speeds (nl, n2), and maintaining one rotation speed (nl) at all times above the other rotation speed (n2) .
PCT/EP2006/066379 2005-09-14 2006-09-14 Motor vehicle automatic transmission and relative actuating method WO2007031563A1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
ITBO20050562 ITBO20050562A1 (en) 2005-09-14 2005-09-14 AUTOMATED TRANSMISSION FOR MOTOR VEHICLES AND PROCEDURE FOR ITS IMPLEMENTATION
ITBO2005A000562 2005-09-14

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WO2007031563A1 true WO2007031563A1 (en) 2007-03-22
WO2007031563A8 WO2007031563A8 (en) 2008-02-21

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Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2920703A1 (en) * 2007-09-06 2009-03-13 Peugeot Citroen Automobiles Sa Synchronization device controlling method for motorized gearbox of hybrid vehicle, involves applying minimum effort to sleeve at beginning of synchronization phase until difference in speeds becomes lower than predetermined high threshold
CN102734395A (en) * 2011-04-14 2012-10-17 杨社彬 Clutchless automatic transmission
DE102012214498A1 (en) * 2012-08-14 2014-02-20 Zf Friedrichshafen Ag Synchronizer for automated gearbox has carrier element, spring element and receiving element that are formed at shift collar for causing frictional engagement between synchronizer element and coupler

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Publication number Priority date Publication date Assignee Title
FR2147592A5 (en) * 1971-07-23 1973-03-09 Ardie Werk Gmbh
FR2583489A1 (en) * 1985-06-14 1986-12-19 Renault Vehicules Ind Electromagnetic device for securely fastening a pinion to its shaft in a gearbox
US5036719A (en) * 1989-12-22 1991-08-06 Razzacki Syed T Strutless synchronizer with composite blocking ring
US6427548B1 (en) * 1999-02-17 2002-08-06 Mannesmann Sachs Ag Automatic transmission
EP1505320A2 (en) * 2003-08-08 2005-02-09 BorgWarner Inc. Method for controlling the engagement force of the synchronizers of a dual clutch transmission

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2147592A5 (en) * 1971-07-23 1973-03-09 Ardie Werk Gmbh
FR2583489A1 (en) * 1985-06-14 1986-12-19 Renault Vehicules Ind Electromagnetic device for securely fastening a pinion to its shaft in a gearbox
US5036719A (en) * 1989-12-22 1991-08-06 Razzacki Syed T Strutless synchronizer with composite blocking ring
US6427548B1 (en) * 1999-02-17 2002-08-06 Mannesmann Sachs Ag Automatic transmission
EP1505320A2 (en) * 2003-08-08 2005-02-09 BorgWarner Inc. Method for controlling the engagement force of the synchronizers of a dual clutch transmission

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2920703A1 (en) * 2007-09-06 2009-03-13 Peugeot Citroen Automobiles Sa Synchronization device controlling method for motorized gearbox of hybrid vehicle, involves applying minimum effort to sleeve at beginning of synchronization phase until difference in speeds becomes lower than predetermined high threshold
CN102734395A (en) * 2011-04-14 2012-10-17 杨社彬 Clutchless automatic transmission
CN102734395B (en) * 2011-04-14 2015-05-13 杨社彬 Clutchless automatic transmission
DE102012214498A1 (en) * 2012-08-14 2014-02-20 Zf Friedrichshafen Ag Synchronizer for automated gearbox has carrier element, spring element and receiving element that are formed at shift collar for causing frictional engagement between synchronizer element and coupler

Also Published As

Publication number Publication date
WO2007031563A8 (en) 2008-02-21
ITBO20050562A1 (en) 2007-03-15

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