Machine element or mechanism – Gearing – Interchangeably locked
Patent
1994-02-17
1996-02-06
Bonck, Rodney H.
Machine element or mechanism
Gearing
Interchangeably locked
192 355, 192 361, 192 363, F16D 2306, B60K 4122, F16H 338
Patent
active
054888786
DESCRIPTION:
BRIEF SUMMARY
CROSS REFERENCE TO RELATED APPLICATIONS
This application is the U.S. national phase of PCT application PCT/EP92/01968 filed 7 Aug. 1992 with a claim to the priority of German application P 41 28 834.8 itself filed 30 Aug. 1991.
FIELD OF THE INVENTION
The invention relates to a gear transmission and a method of operating same. More particularly this invention concerns such a transmission having a controller that switches synchronized jaw clutches responsible for the speed changes and a main clutch that interrupts the traction force.
BACKGROUND OF THE INVENTION
Such gear transmissions are known in many types, for example from published PCT application WO 86/05449 filed 12 Mar. 1985 by G. Bieber. Normally with other synchronized transmissions only the forward ranges are provided with synchronizing devices while the reverse speed ranges have a simple jaw clutch without any synchronizing device. Such transmissions are indeed simple in construction but their gears clash when shifted into reverse due to an excessively high speed differential between the shafts being shifted and the changing time is long since the clashing only slowly decreases the speed differences. In addition this gear-clashing subjects the teeth to wear so that they do not engage properly and eventually can not be shifted easily or at all because one tooth directly engages another.
OBJECT OF THE INVENTION
It is therefore an object to provide and improved and simplified gear transmission and method of operating a gear transmission.
SUMMARY OF THE INVENTION
This object is achieved according to the invention in that the reverse speed ranges have no synchronizing device. After opening of the main clutch the controller at first activates a synchronizing device of a forward-speed range below a programmable maximum rotation rate of the input shaft on shifting into the reverse speed range and releases the device and shifts into the reverse-speed range before the main clutch closes when the rotation speed is below a programmable target rotation rate of the input shaft.
Since the transmission according to the invention has no synchronizing device for the reverse speed ranges it is simple in construction and the main clutch can easily be operated. In spite of this there are no disturbing noises on shifting into reverse because the shafts being shifted by the controller have been brought by means of the synchronizing device of a forward speed range to an acceptable relative rotation rate. This at the same time avoids wear of the jaw clutch for the reverse speed range and shortens the shifting time. In order to more easily shift the jaw clutch for the reverse speed range when the shafts being shifted are synchronized, the jaws in the clutch can be relatively sharp. Thus they fit together easily. An easily determined residual rotation rate can further facilitate the meshing so that an actual tooth-against-tooth positioning is avoided. This is above all dependent on the shape of the jaws.
Basically it is enough to activate the synchronizing device in dependence on the rotation rate of the input shaft or a rotation rate derived therefrom since the driver will know the rotation rate and rotation direction of the output shaft of the transmission based on the movement of the vehicle and will only start shifting into reverse when the vehicle is virtually stationary. Additionally the rotation rate of the output shaft can also be determined by a tachometer and fed to the controller. This establishes the relative rotation speeds of the shafts to be coupled together. In addition it is preferable to break off the shifting operation in dependence on certain criteria and to directly go into the reverse speed range before the main clutch is closed again.
Since during shifting the vehicle should be generally stationary, the rotations to be measured are small so that expensive tachometers are required. One can use simpler devices which have a higher measuring threshold when the higher rotations are compensated for by providing the controller with an empiricall
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patent: 4221283 (1980-09-01), Nordkvist et al.
patent: 4409857 (1983-10-01), Lasoen
patent: 4467665 (1984-08-01), Katayama et al.
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patent: 4785681 (1988-11-01), Kuratsu et al.
patent: 5012416 (1991-04-01), Bulgrien et al.
patent: 5054591 (1991-10-01), Braun
patent: 5103948 (1992-04-01), Sato et al.
patent: 5385223 (1995-01-01), Certeza
Bonck Rodney H.
Dubno Herbert
Jensen Nathan O.
Wilford Andrew
ZR Friedrichshafen AG
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