Continuously variable transmission

Details Continuously variable transmission Continuously variable transmission

2000-03-16

2001-07-17

Wright, Dirk (Department: 3681)

Planetary gear transmission systems or components

Planet pinion is friction gear

Variable speed ratio

C475S192000

Reexamination Certificate

active

06261200

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a continuously variable transmission which is employed as a transmission of an automobile or the like.
2. Description of the Related Art
A troidal-type continuously variable transmission employed as a vehicle transmission or the like has been disclosed, for instance, by Japanese Patent Publications Nos. Hei. 6-506042 and Hei. 1-169169. Each of those continuously variable transmissions has an input shaft which is rotated by a drive source, an output shaft which outputs a driving force attributing to the rotation of the input shaft; a speed ratio changing device, namely, a variator which is arranged between the input shaft and the output shaft, and a planet gear mechanism.
What is disclosed in Japanese Patent Publication No. Hei. 6-506042 is a gear neutral system which performs driving force circulation in a low speed mode. Its planet gear mechanism has a low speed clutch and a high speed clutch. When the low speed clutch is connected, and the high speed clutch is disconnected (released), the driving force is transmitted from the planet gear mechanism to the output shaft, and a part of the driving force is transmitted to the variator.
On the other hand, what is disclosed by Japanese Patent Publication No. Hei. 1-169169 is a power split system which perform driving force circulation in a high speed mode. Its planet gear system has a low speed clutch, and a high speed clutch. When the low speed clutch is disconnected while the high speed clutch is connected, the rotational driving force of the input shaft is transmitted to the output shaft directly through the planet gear mechanism (instead of the variator), and a part of the driving force is transmitted to the variator.
That is, in any one of the systems, the low speed clutch and the high speed clutch are provided, and in the case of the mode change, when the rotations in the clutch section are equal to each other, the clutch connection is changed.
However, the conventional troidal-type continuously variable transmission has no means which confirms whether or not a first power transmitting system which is inputted to the planet gear mechanism through the variator is equal in the number of revolutions to a second power transmitting system which is inputted directly (not through the variator) to the planet gear mechanism. In addition, even when a predetermined change gear ratio is not reached, or the gear change is over, or the gear change becomes impossible because the variator becomes out of order, the clutch is changed. Therefore, the clutch is not connected, or damaged. Furthermore, if the clutch is changed when the numbers of revolutions are different, then a gear change shock occurs, which makes the driver or other persons on the vehicle feel bad.
SUMMARY OF THE INVENTION
In view of the foregoing, an object of the invention is to provide continuously variable transmission with which the clutch change is achieved smoothly in the case of mode change, and the damage of the clutch board is prevented, and the gear change shock, which otherwise may be applied to the driver and other persons on the vehicle, is prevented.
The foregoing object of the invention has been achieved by the provision of a continuously variable transmission comprising: an input shaft rotated by a drive source; an output shaft for taking out a driving force attributing a rotation of the input shaft; a variator being arranged between the input shaft and the output shaft; a planet gear mechanism arranged between the input shaft and the output shaft; a switching member for switching a first mode in which a driving force circulation through the variator is carried out and a second mode in which a driving force circulation through the variator is not carried out; and detecting member for detecting a ratio of speed of a first driving force transmitting system which is inputted to the planet gear mechanism through the variator, and a ratio of speed of a second driving force transmitting system which is inputted to the planet gear mechanism directly, not through the variator, wherein, when the detecting member detect a substantial coincidence in the ratios of speed of the first and second driving force transmitting systems, the detecting member performs a mode switching operation using the switching member.
With the continuously variable transmission designed as described above, during a low speed traveling operation, the clutch is changed so that the carrier of the planet gear mechanism is connected to the ring gear while the second driving power transmitting system is disconnected from the ring gear. Under this condition, only the variator transmits the driving power from the input shaft to the output shaft. During the high speed traveling operation, the clutch is changed so that the second driving power transmitting system is connected to the ring gear while the carrier is disconnected from the ring gear. In addition, under this condition, the torque is transmitted from the carrier forming the planet gear mechanism to the output disk of the variator through the second driving power transmitting system. Under this condition, the speed change ratio of the continuously variable transmission is, as a whole, changes according to the speed of revolution of the planet gear. Therefore, by changing the speed change ratio of the variator thereby to change the speed or evolution of the planet gear, the speed change ratio of the continuously variable transmission an be adjusted as a whole.
The speed (rpm) of the first driving force transmitting system is detected by the speed ratio detecting member, namely, the first speed detecting sensor, while the speed of the second driving force transmitting system is detected by the second speed detecting sensor, and the detection signals thereof are applied to the control circuit. When the speeds thus detected are equal to each other or substantially equal to each other, the control circuit applies a signal to the drive section of the high speed clutch and the low speed clutch. In response to the instruction signal, the mode change operation is carried out that the high speed clutch is connected while the low speed clutch and the backward clutch are disconnected (released).


REFERENCES:
patent: 5090951 (1992-02-01), Greenwood
patent: 5178043 (1993-01-01), Nakano
patent: 5238460 (1993-08-01), Esaki et al.
patent: 5669845 (1997-09-01), Muramoto et al.
patent: 5674145 (1997-10-01), Kidokoro et al.
patent: 5888160 (1999-03-01), Miyata et al.
patent: 6074320 (2000-06-01), Miyata et al.
patent: 6171210 (2001-01-01), Miyata et al.
patent: 41 07 739 (1991-09-01), None
patent: 1-169169 (1989-07-01), None
patent: 01312265 (1989-12-01), None
patent: 1-312266 (1989-12-01), None
patent: 6-21625 (1994-03-01), None
patent: 7-96901 (1995-10-01), None
patent: 9-89071 (1997-03-01), None
patent: 9-210191 (1997-08-01), None
patent: 10267116 (1998-10-01), None
patent: 11108147 (1999-04-01), None
patent: WO 91/08406 (1991-06-01), None
“The Design and Development of an Experimental Traction Drive CVT for a 2.0 Litre FWD Passenger Car”, Fellows et al., SAE Technical Paper Series, International Congress & Exposition Detroit, Michigan Feb. 25, 1991-Mar. 1, 1991; pp. 9-19.

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