Planetary gear transmission systems or components – Nonplanetary variable speed or direction transmission... – Nonplanetary transmission is friction gearing
Reexamination Certificate
2000-06-01
2002-03-19
Marmor, Charles A. (Department: 3681)
Planetary gear transmission systems or components
Nonplanetary variable speed or direction transmission...
Nonplanetary transmission is friction gearing
C475S218000
Reexamination Certificate
active
06358179
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to control of a clutch used for an infinite variable speed ratio transmission for vehicles.
BACKGROUND OF THE INVENTION
Tokkai Hei 10-325459 published by the Japanese Patent Office in 1998 discloses an infinite variable speed ratio transmission (hereinafter referred to as IVT) wherein a speed ratio is continuously varied to infinity by combining a fixed speed ratio transmission and planetary gear mechanism with a continuously variable transmission (hereinafter referred to as CVT).
In the IVT, the CVT whereof the speed ratio can be changed continuously, and the fixed speed ratio transmission, are respectively joined to an input shaft connected to an engine. The output shaft of the CVT is joined to a sun gear of the planetary gear mechanism, and the output shaft of the fixed speed ratio transmission is joined to a planet carrier of the planetary gear mechanism via a power recirculation mode clutch.
A ring gear of the planetary gear mechanism is connected to a final output shaft so as to extract an output rotation of the IVT.
The rotation output of the CVT can also be directly input to the final output shaft via a direct mode clutch.
In the power recirculation mode wherein the power recirculation mode clutch is engaged and the direct mode clutch is disengaged, the speed ratio of the IVT, i.e., the ratio of the rotation speeds of the input shaft and final output shaft, changes continuously from a negative value to a positive value including infinity according to the difference of the speed ratios of the toroidal CVT and the fixed speed ratio transmission,.
In the direct mode wherein the power recirculation mode clutch is disengaged and the direct mode clutch is engaged, the product of the speed ratio of the CVT and the speed ratio due to a chain which joins the CVT with the sun gear, is the speed ratio of the IVT.
SUMMARY OF THE INVENTION
In the IVT, the clutch pressures of the power recirculation mode clutch and the direct mode clutch are controlled independently except when there is a change-over of mode.
Hence, if the controller which controls the clutch pressure breaks down, or when a valve stick occurs in the oil pressure system which supplies the clutch pressure, both of the clutches may be engaged simultaneously.
When both the power recirculation mode clutch and direct mode clutch are engaged, the IVT forcibly changes the speed ratio so that the rotation speed of the final output shaft in the power recirculation mode coincides with the rotation speed of the final output shaft in the direct mode.
Thus, due to this forced variation of speed ratio, a speed ratio variation unintended by the driver may occur even when the vehicle is running in the power recirculation mode or direct mode.
It is therefore an object of this invention to prevent a speed change unintended by the driver when there is a malfunction of the controller or oil pressure system.
In order to achieve the above object, this invention provides a clutch control device for such an infinite variable speed ratio transmission for a vehicle that comprises an input shaft, a continuously variable transmission which transmits a rotation of the input shaft at an arbitrary speed ratio to a continuously variable transmission output shaft, a fixed speed ratio transmission which transmits the rotation of the input shaft at a fixed speed ratio to a fixed speed ratio transmission output shaft, a planetary gear mechanism having a first rotation member connected to the continuously variable transmission output shaft, a second rotation member connected to the fixed transmission output shaft, and a third rotation member varying a rotation direction and a rotation speed according to a difference of a rotation speed of the first rotation member and a rotation speed of the second rotation member, a direct mode clutch which engages to connect the continuously variable transmission output shaft and the third rotation member, and disengages to disconnect the continuously variable transmission output shaft and the third rotation member according to a supplied oil pressure, and a power recirculation mode clutch which engages to connect the fixed speed ratio transmission output shaft and the second rotation member, and disengages to disconnect the fixed speed ratio transmission output shaft and the second rotation member according to a supplied oil pressure.
The clutch control device comprises a first valve for supplying an oil pressure to the direct mode clutch and power recirculation mode clutch, a mechanism for detecting a running condition of the vehicle, a mechanism for controlling the first valve according to the running condition, and a mechanism for preventing simultaneous engagement of the direct mode clutch and the power recirculation mode clutch by overriding a control of the first valve by the control mechanism when the running condition does not correspond to a predetermined specific region, and permits simultaneous engagement of the direct mode clutch and the power recirculation mode clutch when the running condition corresponds to the predetermined specific region.
The details as well as other features and advantages of this invention are set forth in the remainder of the specification and are shown in the accompanying drawings.
REFERENCES:
patent: 5063815 (1991-11-01), Oshidari
patent: 5935039 (1999-08-01), Sakai et al.
patent: 5980420 (1999-11-01), Sakamoto et al.
patent: 6287232 (2001-09-01), Sakai et al.
patent: 4300449 (1992-10-01), None
patent: 9-89071 (1997-03-01), None
patent: 10-267117 (1998-10-01), None
patent: 10-325459 (1998-12-01), None
Hirano Hiroyuki
Oshidari Toshikazu
Sakai Hiromasa
Ho Ha
Marmor Charles A.
Nissan Motor Co,. Ltd.
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