Planetary gear transmission systems or components – Fluid drive or control of planetary gearing – Fluid controlled mechanical clutch or brake
Patent
1997-02-14
1999-03-23
Wright, Dirk
Planetary gear transmission systems or components
Fluid drive or control of planetary gearing
Fluid controlled mechanical clutch or brake
475258, 475267, F16H 6330, F16H 6102
Patent
active
058851801
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
The present invention relates to an automatic transmission device having at least two ratios, in particular for a vehicle.
The present invention also relates to a method of controlling such a transmission device.
RELATED TECHNOLOGY
WO-A-9207206 discloses an automatic transmission in which a clutch selectively connects two rotary members of a differential gearing, such as an epicyclic train, according to whether one or other of two antagonistic forces is stronger. Such forces are for example an axial thrust produced by an axially movable helical gear, tending to release the clutch against the action of springs and/or a force produced by a centrifugal tachometric means, tending to engage the clutch. When the clutch is released, it is necessary to prevent rotation of a third rotary member of the differential gearing, and this can be ensured by a free wheel preventing this third member from rotating in the reverse direction.
This type of transmission is very advantageous as its basic functioning requires neither an external power source, nor sensors, nor a control circuit. It is the transmission device itself which produces the forces which will control it and these forces are at the same time measurement of the parameters necessary for the control.
However, such a transmission device is not directly capable of optimising the hold-back operation, that is to say when the accelerator pedal is released so that the engine provides a certain braking of the vehicle. In this case, the resistant torque of the engine no longer depends on anything else than its rotating speed and is not therefore indicative of the deceleration desired by the driver. Furthermore, in the case in which the torque is detected by a reaction of helical teeth, this reaction changes direction during hold-back operation and therefore it no longer tends to release the clutch. Furthermore, in the case of the structure using a free wheel, even if the reaction of the teeth was capable of releasing the clutch in order thus to create one of the conditions for speed-reducing operation, another condition would remain unsatisfied: during the hold-back operation, the third rotary member of the differential gearing tends to rotate not in the reverse direction, but at high speed in the normal direction, which the free wheel cannot prevent.
W094/19629, published after priority date enjoyed by this invention, describes how it is possible to selectely add an additional force in order to allow the hold-back operation and also to cause the transmission device to operate, in certain other cases, with another transmission ratio than that which would result from the comparison between the two basic antagonistic forces. It is thus possible to cause the transmission device to operate with a lower ratio when the driver of the vehicle presses the accelerator pedal fully down, even at speeds at which, for example, the centrifugal force, which is proportional to the square of the speed, would normally impose operation at the highest ratio.
Problems of shocks have occurred during changes of ratio. For example, such a shock occurs if the driver happens to release the accelerator pedal when the centrifugal force is in the process of making the transmission device change from the lower ratio to the higher ratio. In this case, the nascent supremacy of the centrifugal force is suddenly increased, and the changing of the coupling device to the coupled state can be sudden. The same thing can occur when the control process causes the additional force to vary, for example causes it to disappear.
U.S. Pat. No. 4,713,984 discloses a transmission device in which the clutches are not controlled by forces among which one of them would be the measurement of an operating parameter, but by mere hydraulic actuators controlled by decision means of the transmission. Means are provided to prevent shocks by restricting the oil flow rates during pressurization and during draining of the hydraulic chambers.
According to EP-A-0 149 012, in a similar configuration, the c
REFERENCES:
patent: 5106348 (1992-04-01), Koivunen
patent: 5263906 (1993-11-01), Antonov
patent: 5409428 (1995-04-01), Antonov
patent: 5514043 (1996-05-01), Antonov
patent: 5514044 (1996-05-01), Antonov
patent: 5655984 (1997-08-01), Antonov
patent: 5704459 (1998-01-01), Antonov
Antonov Automotive Technologies B.V.
Kwon Peter T.
Wright Dirk
LandOfFree
Transmission device, more particularly for a vehicle, and a cont does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Transmission device, more particularly for a vehicle, and a cont, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Transmission device, more particularly for a vehicle, and a cont will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2120565