Planetary gear transmission systems or components – Nonplanetary variable speed or direction transmission... – Nonplanetary transmission is friction gearing
Reexamination Certificate
1999-08-09
2001-04-17
Estremsky, Sherry (Department: 3681)
Planetary gear transmission systems or components
Nonplanetary variable speed or direction transmission...
Nonplanetary transmission is friction gearing
C477S041000
Reexamination Certificate
active
06217473
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a toroidal type continuously variable transmission, in particular, to a structure of continuously variable transmission for a front engine front wheel drive vehicle employing a geared neutral starting system.
DESCRIPTION OF THE PRIOR ART
A toroidal type continuously variable transmission, which continuously changes a speed ratio of power transmission between an input disk and an output disk by interposing a roller for making the power transmission between both disks and by rotating this rotor with a variable inclination angle so as for contact points thereof with each of said both disks to be changed in a radial direction respectively, is now being introduced into practical use as a continuously variable transmission for automobile, and, as shown, for example, in the official gazette of Japanese Patent Un-examined Publication No. 6-101754, a geared neutral starting system has been proposed to use in this type continuously variable transmission.
In this system, the continuously variable transmission mechanism having the structure described above is disposed on a first shaft coupled with an engine, and a planetary gear mechanism comprising three rotary elements, that is, a sun gear, an internal gear, and a pinion carrier for supporting a planetary pinion engaging with these both gears, is also disposed on a second shaft which is parallel with the first shaft, wherein a revolution of the engine is transmitted to the first rotary element directly, and to the second rotary element through the continuously variable transmission mechanism mentioned above and the third rotary element is made to be a power output element.
A neutral condition is realized by controlling the speed ratio of the continuously variable transmission mechanism so that a ratio of input rotation speeds between the first and the second rotary elements of the planetary gear mechanism is controlled so as to stop the third rotary element, and, starting form this condition, the third rotary element, which is the power output element, is rotated in the forward or the reverse direction by increasing or decreasing the speed ratio of the continuously variable transmission mechanism.
This system allows the vehicle to be started without using a clutch, a torque converter and the like, and this improves a response in starting and an efficiency of power transmission.
When above mentioned geared neutral system is employed, two power transmission paths are necessary, one of which transmits the power from the first shaft side to the planetary gear mechanism on the second shaft without interposing the continuously variable transmission mechanism therebetween, and the other of which transmit the power from the first shaft side to the planetary gear mechanism through the continuously variable transmission mechanism, and therefore, in the continuously variable transmission disclosed in the above official gazette, the latter power transmission path is provided in the middle of a tandem type transmission gear mechanism and the former power transmission path which builds up a gear train for a low mode reduction gear system is provided in the engine side of the continuously variable transmission mechanism.
In this type of structure, however, especially in the transmission for the front engine front wheel drive vehicle, there occurs problems as below.
That is, in the transmission for the front engine front wheel drive vehicle, as shown in
FIG. 3
of the above gazette, a differential gear unit is generally connected to an engine side end of the second shaft (, which is an output shaft of a transmission unit) on which the planetary gear mechanism is disposed, so that, in this case, the gear train for directly transmitting the power from the first shaft side to the planetary gear mechanism on the second shaft must be disposed near by the differential gear unit having a large diameter. Accordingly, in order to avoid an interference between the gear train and the differential gear unit, they must be placed with some distance therebetween with respect to the shaft direction, which increases the size of the transmission along the shaft direction. Especially in the front engine front wheel drive vehicle which has a shaft line of the engine and the transmission disposed laterally with respect to the vehicle center line, the increased size in this shaft line direction makes a mounting operation to a vehicle body as well as a layout design of the engine and the transmission difficult.
Accordingly, the object of the present invention is to increase an allowance for the layout and the mounting operation to the vehicle body of the toroidal type continuously variable transmission of the front engine front wheel drive vehicle employing the geared neutral starting system by controlling the increase of the size in the shaft direction.
SUMMARY OF THE INVENTION
In order to solve the problem mentioned above, the present invention is characterized by the constitution described below.
In an invention claimed in claim
1
of the present invention (hereafter referred to as the first invention), a first shaft engaged with an engine on one end thereof and a second shaft disposed parallel with said first shaft and engaged, on an engine side end thereof, with a differential gear unit for driving a left and a right driven wheel are provided, and on said first shaft is disposed a toroidal type continuously variable transmission mechanism comprising an input disk coupled with said first shaft, an output disk disposed in the engine side of said input disk and rotatably supported by the first shaft, a roller interposed between these disks for transmitting a power between both disks, and a contact point control member for changing a speed ratio between both disks by inclinably and rotatably supporting said roller and thereby changing the contact point between said roller and each of the input and the output disks, and on said second shaft is disposed a planetary gear mechanism comprising three rotary elements, that is, a sun gear, an internal gear and a pinion carrier, wherein, among these rotary elements, the first element is coupled with the output disk of the continuously variable transmission mechanism so as to rotate together with it and the second element is coupled with the second shaft.
Above described system is characterized in that a gear train comprising a first gear disposed on the opposite side with respect to the engine of the continuously variable transmission mechanism mounted on the first shaft so as to rotate together with said first shaft, a second gear rotatably supported on the opposite side with respect to the engine of the planetary gear mechanism mounted on the second shaft, and an idle gear which is engaged with these gears to transmit a power between both gears is further provided, and furthermore a first clutch mechanism for engaging or disengaging the second gear of this gear train with the third element of the planetary gear mechanism, a second clutch mechanism for engaging or disengaging the output disk of the continuously variable transmission mechanism with the second shaft, and a control means for controlling operations of said first and said second shaft, and a control means for controlling operations of said first and said second clutch mechanism and the contact point control member are provided.
Preferably, a vehicle speed detecting means is further provided, and said control means is characterized in that it controls said first clutch so as to engage said second gear with said third element and at the same time controls said second clutch so as to intercept said power transmission path while the vehicle speed being lower than a predetermined vehicle speed, and controls the first clutch so as to intercept the engagement between the second gear and the third element and at the same time controls the second clutch so as to engage the power transmission path while the vehicle speed being higher than said predetermined vehicle speed.
In addition, an engine load detector is prefe
Nakane Hisanori
Takedomi Hidenao
Ueda Kazuhiko
Uesugi Tatsuya
Abrams Hugh A.
Estremsky Sherry
Mazda Motor Corporation
Sidley & Sutin
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