Machine element or mechanism – Gearing – Interchangeably locked
Reexamination Certificate
1999-04-14
2001-11-27
Bucci, David A. (Department: 3682)
Machine element or mechanism
Gearing
Interchangeably locked
C074S337500, C074S473100, C074S473120, C074S473210
Reexamination Certificate
active
06321612
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention relates to an actuating mechanism for the automatic operation of a gear-shift in a transmission.
2. Description of the Related Art
Actuating mechanisms for the automatic operation of gear-change in a transmission that allow different driving gears to be selected in any desired sequence are known for example from German reference DE 197 06 214 A1. These prior art actuating mechanisms comprise a first drive for driving a selector shaft in the axial direction and a second drive for driving the selector shaft in rotary fashion. One of these two movement types corresponds to shift path selection and the other to gear selection. The association of the drives to the movement type is specific to the particular transmission. A disadvantage of this type of prior art actuating devices for the automatic operation of speed-change transmissions is that when the desired gearshift procedure involves shift path selection such, for example, as shifting from second gear to third gear in an H-shaped shifting gate, it is necessary to activate a first drive to disengage the current gear and to then slow down again to assume the neutral position. When the neutral position is reached, the second drive is activated to change the shift path position. When the desired shift path position is reached, the first drive is again activated to engage the desired driving gear. The first drive for gear selection must be powerful enough to provide the force required for synchronization. Such drives have large inertial masses, which must be accelerated or retarded during every activation or braking of the engine, resulting in reaction inertia. The large inertial mass of the first drive causes a gearshift duration experienced as disruptive by the driver when the change in gear involves a shift path selection, due to the interruption in tractive force during the gearshift procedure.
Further, the automatic operation of a gear-change in a transmission by a gear-change cylinder drivable by an associated drive is known, for example, from German reference DE 197 13 423 A1. When this prior art type of actuating device is used, the individual driving gears are activated by the gear-change cylinder in a predetermined sequence only. If the driver wishes to skip one or more driving gears, the intervening gears must nonetheless be engaged at least briefly to allow the desired gear to be engaged. As a result, greater stress is placed on the synchronization devices. Moreover, the requirement to pass through the intervening gears lengthens the time to required to implement the desired change in gear.
SUMMARY OF THE INVENTION
The object of the invention is to further develop an actuating device for the automatic operation of a gear-change in a transmission such that the time required to shift gears, especially in the case of gear shifts that involve shift path selection, is shortened for at least some of the possible gear changes.
This object is attained according to a first embodiment of the invention by an actuating device for the automatic operation of a gear change in a transmission having a plurality gears corresponding to a plurality of translation ratios, the actuating device comprising a rotatably and axially movable selector shaft operatively connectable to the transmission for selecting one of the plural gears, a first drive is operatively connected to said selector shaft via a guide mechanism, said guide mechanism comprising at least one constraint guide corresponding to a shifting path of said selector shaft for effecting a gear change between two of said plural gears, and a second drive operatively connected to said selector shaft for providing an operating force having a first force component along an axial direction of said selector shaft and a second force component along a circumferential direction of said selector shaft for urging said selector shaft along a movement path determined by an operating position of said guide mechanism.
As stated above, the actuating device comprises a first drive that is connected to the selector shaft via a guide mechanism. The guide mechanism comprises at least one constraint guide that corresponds to a shift path. The at least one constraint guide is preferably selected by the first drive. When a force is exerted on the selector shaft, the selector shaft executes a movement determined by the constraint guide. To provide the force exerted on the selector shaft for the purpose of the gear-change operation, a second drive is actively connected to the selector shaft. The resultant force exerted on the selector shaft has a component in the axial direction of the selector shaft as well as a component in the tangential direction of the selector shaft. For example, the second drive is actively connected to the selector shaft via a worm gear or a universal joint and crank gear. Because the constraint guide ensures that the selector shaft executes the actuating travel required for the desired gear change in response to a continual activation of the drive that substantially provides the operating force, the gearshift duration is shortened for a plurality of gearshift procedures. This is especially true for gearshift procedures that involve shift path selection and crossing of the neutral position.
According to a second embodiment of the invention, the aforementioned object is attained by an actuating device for the automatic operation of a gear-change in a transmission that comprises a first drive and a second drive which interact to cause a predetermined movement of the selector shaft depending on the gearshift procedure to be carried out. At least one of the two drives acts upon the selector shaft via a guide arrangement. The other drive is energized to produce an operating force to co-determine the course of the selector shaft movement with the guide arrangement.
For example, when one of the drives is activated, the guide arrangement may permit or cause the selector shaft to move in the longitudinal direction.
In addition, when the other of the drives is activated, the guide arrangement may permit or cause the selector shaft to move in both the longitudinal direction and a rotional direction.
It has proved advantageous for the guide arrangement to comprise at least two constraint guides. A first constraint guide corresponds to a gearshift procedure without shift path selection and a second constraint guide corresponds to a gearshift procedure with shift path selection. The first drive can select either of the two constraint guides, so that when an operating force is initiated by the second drive, the selector shaft executes a movement consistent with the selected one of the constraint guides.
It has also proved advantageous to activate the first drive during the gearshift procedure such that the constraint guide executes a movement during the gear-change operation to permit a movement of the selector shaft that deviates from the movement determined solely by the constraint guide. The movement caused by the first drive is superimposed with the movement determined by the constraint guide to cause the selector shaft to move in a desired shifting movement.
Further, it has proved advantageous to have one of the constraint guides to correspond to a shifting movement from second gear to third gear and from fourth gear to fifth gear, because these gear changes occur frequently during normal driving operation.
An advantageous embodiment of a guide arrangement comprises an input part and an output part. The input part is drivable by the first drive. The output part is securely connected to the selector shaft and is preferably embodied in a single piece with the selector shaft. The desired one of the constraint guides may be activated by moving the input part relative to the output part. The input part and the output part are in an engaged arrangement with each other, as a result of which the first drive is connected to the selector shaft.
It has also proved advantageous for the guide arrangement to have a slot into which a project
Horst Alexander
Leimbach Lutz
Ratte Andreas
Wirth Thomas
Bucci David A.
Cohen & Pontani, Lieberman & Pavane
Joyce William C
Mannesmann Sachs AG
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