Machine element or mechanism – Gearing – Interchangeably locked
Reexamination Certificate
2001-10-12
2004-02-17
Parekh, Ankur (Department: 3681)
Machine element or mechanism
Gearing
Interchangeably locked
C701S059000
Reexamination Certificate
active
06691588
ABSTRACT:
This application is based on and claims priority under 35 U.S.C. §119 with respect to Japanese Application No. 2000-313010 filed on Oct. 13, 2000, the entire content of which is incorporated herein by reference.
FIELD OF THE INVENTION
The present invention is generally directed to a synchromesh-type transmission of a vehicle. More particularly, the present invention pertains to an actuator control for a shifting device in a synchromesh-type vehicle transmission.
BACKGROUND OF THE INVENTION
One known type of vehicle transmission is a synchromesh-type transmission which transmits a rotation from a source of power to the driving wheels in an automotive vehicle. In this type of transmission, the power transmission path extending from the source of power to each of the driving wheels includes no sliding parts or components. Thus, unlike automatic transmissions, synchromesh-type transmissions have the advantage that a highly responsive driving feeling can be obtained resulting from a relatively quick response of the driving wheels when the driver depresses the acceleration pedal. In addition, fuel or gas consumption can be reduced, thus contributing to energy savings.
To make the driver's gear shift or changing gear ratio much easier than that in the conventional fully manually operated transmission, while also enjoying the above-mentioned advantages, techniques have been developed for changing the gear ratio of a synchromesh type transmission through operation of an electrically controlled actuator. One example is disclosed in Japanese Unexamined Patent Publication No. 2000-46176.
The transmission which is in association with a shifting device of the kind includes a synchromesh mechanism in which one of a plurality of continually meshed gear pairs of different gear ratios is selected as a valid gear pair.
The synchromesh mechanism includes a sleeve and a synchronizer ring. The sleeve is rotatable together with the shaft and is movable in the axial direction of the shaft on which one of the gear pair is mounted as an idle gear, which is free to rotate relative to the shaft. The synchronizer ring is free to rotate and move in an axial direction relative to the idle gear.
When the synchromesh mechanism is made active, synchronization is established between the idle gear and the sleeve by moving the sleeve in the axial direction to engage the synchronizer ring to thereby causing the synchronizer ring to push on a frictional surface which is incapable of rotating relative to the idle gear and a balk is established until the synchronization is completed which prevents a clutch which is incapable of rotating relative to the sleeve from being engaged with another clutch which is incapable of rotating relative to the idle gear.
The above-mentioned shifting device includes an actuator and a control device, with the actuator being controlled electrically in response to an external signal to generate a load for moving the sleeve in the axial direction. The control device feeds a driving signal to the actuator to change the gear ratio of the transmission on the basis of the driver's intention and the state of the vehicle.
The shifting device should preferably be designed to change the gear ratio of the transmission without an improper feeling. To address this need, it is desirable to control the synchronization time duration as the time passing duration ranging from initiation to termination of each synchronization operation in the transmission in such a manner that actual synchronization time durations are made stable or equalized when plural synchronization operations are performed.
SUMMARY OF THE INVENTION
The present invention provides an improved shifting device associated with a synchromesh-type transmission for changing the gear ratio of the transmission which transmits rotation from a power source to driving wheels. The transmission includes a synchromesh mechanism having a plurality of constantly meshed gear pairs possessing different gear ratios, with one of the gear pairs being selected as an effective gear pair. The synchromesh mechanism also has a sleeve and a synchronizer ring, with the sleeve being mounted on a shaft on which one of each of the gear pairs is mounted as an idle gear. The sleeve is rotatable together with the shaft and is movable in the axial direction of the shaft. The synchronizer ring is rotatable and movable relative to the idle gear, and the synchromesh mechanism is brought into operation to establish synchronization between the idle gear and the sleeve in such a manner that the sleeve is moved in the axial direction to be engaged with the synchronizer ring, and subsequently the engaged synchronizing ring is urged onto a friction surface of the idle gear so as to be rotatable together with the idle gear. The shifting device includes an electrically controlled actuator generating a load for acting on the sleeve to move the sleeve in the axial direction in response to a driving signal, and a control device outputting the driving signal to the actuator upon current synchronization control to change the gear-ratio of the transmission on the basis of at least one of the vehicular driver's intention, the state of the vehicle, and the state of the transmission. The control device includes a driving signal determination mechanism for determining the driving signal on the basis of an initial relative rotation number and a relative rotation number deviation. The initial relative rotation number being is as a relative rotation between the idle gear and the sleeve at initiation of the current synchronization control. The relative rotation number deviation is a deviation between a target relative rotation number and an actually detected relative rotation number. The target relative rotation number is between the idle gear and the sleeve at the latest synchronization control, while the actually detected relative rotation number is between the idle gear and the sleeve at the latest synchronization control.
Theoretically speaking, in a typical synchromesh-type transmission, a fixed relation is found between the initial relative rotation number, the synchronization time duration, and the sleeve load, so that the initial relative rotation number is the relative rotation number between the idle gear and the sleeve at an initiation of a specific synchronization, the synchronization time duration is the elapsed time duration from the initiation to termination of the synchronization, and the sleeve load is a load applied to the sleeve from an actuator. Thus, if a predetermined synchronization time duration is employed as the target synchronization time duration, based thereon, the sleeve load is determined or decided relative to the initial relative rotation number and consequently a suitable driving signal is applied to the actuator for realizing the determined sleeve load. In such a way, the initial relative rotation number is an effective or a valid physical quantity for determining the driving signal throughout the synchronization control.
Moreover, an error in the driving signals in the latest or previous synchronization control is reflected in the relative rotation number deviation which is the deviation of the actual relative rotation number in the latest synchronization control from the target relative rotation number. Thus, taking into account the relative rotation number deviation in the latest synchronization control makes it possible to make the relation between the initial rotation number and the driving signal more adequate or appropriate in each synchronization control.
In view of the above, in the shifting device here, the driving signal to be applied to the actuator in each synchronization control is determined on the basis of the initial relative rotation number in each synchronization control and the relative rotation number deviation in the latest synchronization control. Thus, despite that the driving signal which governs the entirety of each synchronization is determined on the basis of the initial relative rotation number, the control error in
Aoyama Yoshiyuki
Choshi Ryuji
Ichikawa Yoshihiro
Kamiya Mitsutoshi
Miyazaki Takeshige
Aisin AI Co., Ltd.
Burns Doane , Swecker, Mathis LLP
Parekh Ankur
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