Endless belt power transmission systems or components – Control for variable input to output speed-ratio
Reexamination Certificate
2002-04-02
2003-12-30
Charles, Marcus (Department: 3682)
Endless belt power transmission systems or components
Control for variable input to output speed-ratio
C474S046000, C474S030000, C474S023000
Reexamination Certificate
active
06669589
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a continuously variable transmission used for general industrial machineries, vehicles, electric motors and so on, and particularly to a variable transmission for controlling a variable torque while distinguishing and supplying the elastic force and the pressing force to a pulley and performing the friction force stabilization and the high efficient transmission.
2. Related Art
The motion of a fixed horse power type belt continuously variable transmission has been developed in U.S. Pat. Nos. 4,973,288, 5,269,726 and the like, but satisfactory products have not been realized. Both the patents have an idea that in the former, input and output pulleys are simultaneously pressed by oil pressure and in the latter, by screw winding up. However, these ideas have decisive and important or principle defects. Normally, the output horse power P [W] which is transmitted by an output pulley to a load is determined by a relation formula P=1.027×N×T between the rotating speed N [rpm] and the torque T [Kgm]. The rotating speed is decided by a contact position between a belt and a pulley, that is, a radius ratio, while the torque is decided by a contact friction pressure therebetween. This means that the rotating speed is determined merely by the positioning control of the belt in the pulley, while the shaft torque is always determined merely by the friction pressure control of the pulley. Accordingly, with respect to the securing measures for the desired rotating speed and torque in the continuously variable transmission, the aforementioned relation equation itself shows that the variable pitch positioning control and the friction pressure control are distinguished and applied to the pulleys and synchronously operated mutually. However, in the ideas of the above-described U.P. patents, even if the positioning function by a supply of pressing force should be applied synchronously to the input and output pulleys, there is no assurance of always maintaining a proper belt position, and not to mention, the torque assurance function for always applying the desired friction force to both the pulleys is not present at all in the transmitting system. This indicates that in the ideas of the aforesaid patents, secureness and maintenance of proper rotating speed and torque can not be accomplished, and the desired horse power transmission is impossible in terms of principle.
On the other hand, the present applicant has proposed, in EP Application publication No. EP 0931960A2, separation of roles for functions of the pressing control and the positioning control to two input and output pulleys. However, some unsolved problems still remain. The first problem is that the friction force between the belt and the pulley is instable, and the second problem is that the transmission efficiency is deteriorated. The former disables the transmission in the low speed area of a tension type belt. The cause is that in the friction force securing measures by the external pressing to the pulley directly, when the contact radius or area increases, the friction coefficient of the transmission surface becomes instable to bring forth the surplus friction force. In the latter, even a compression type belt, the transmission efficiency is maximum at and in the vicinity of the speed ratio &egr;=1 but in the other speed ratio areas, the contact area of both the pulleys is unbalanced and the efficiency is worsened therein. That is, the cause is supposed to result from the simultaneous generation of heat generation caused by the moving-in or rolling-in of the belt due to the surplus friction force on the side where the contact area in both the pulleys increases, and heat generation of a slip due to the short of friction force on the side where the contact area reduces.
SUMMARY OF THE INVENTION
It is a common object of the present invention to provide a continuously variable transmission particularly suitable for a constant horse power type in which when the friction force between a variable pitch pulley V-groove and a V-belt is controlled by a supply of external pressing force of an operating unit, the friction force of the other pulley is controlled by a supply of external elastic force in order to secure a shaft torque of one pulley out of input and output pulleys, the shaft torque of said one pulley is indirectly adjusted via a belt tension, not being restricted by the kind of belts.
It is a first object of the present invention to provide an arrangement wherein particularly in order to secure a torque of an output pulley, a controlling device compensates for a short of the friction force of an input pulley, always supplies the elastic force to the input pulleys to variably control the friction force of the input pulley, and to indirectly perform variable torque control the output pulley via a belt tension.
It is a second object of the present invention to provide an arrangement wherein in order to avoid rolling-in of a belt caused by direct pressing to an output pulley to stably secure the output friction force, a controlling device variably press-controls a pressing value for always supplying the elastic force to an input pulley, indirectly makes use of a wedge effect of an output pulley V-groove to control the output friction force and variably controls torque, whereby a constant horse power transmission is achieved with high efficiency and stableness in particularly a large ratio area without being restricted by the kinds of belts such as a tension type or a compression type.
It is a third object of the present invention to provide a continuously variable transmission which enlarges the whole variable speed area and has the optimum transmitting efficiency, wherein a short of the friction force of an input pulley and a surplus of the friction force of an output pulley in a large ratio area are suppressed, and also a surplus of the friction force of an input pulley and/or a short of the friction force of an output pulley in a small ratio area are suppressed.
It is a fourth object of the present invention to provide a continuously variable transmission performing the high efficient and stable transmission, wherein when said third object is embodied, an operating mechanism capable of distinguishing the pressing force and the elastic force and/or a simple pressing mechanism capable of distinguishing and supplying the pressing force and the elastic force are disposed on one of input and output pulleys and on the other, respectively.
It is a fifth object of the present invention to provide an operating mechanism capable of distinguishing and supplying, in response to respective instructions, the non-elastic pressing force for accurately positioning a pulley V-groove to a variable disk of one or both of an input pulley and an output pulley of a continuously variable transmission, and the elastic fore for settling the absorption of errors, impact vibrations or the like caused in the transmitting operation.
It is a sixth object of the present invention to provide a pressing mechanism, which is further simplified in said fifth object, capable of distinguishing and supplying, in response to a single control instruction, the non-elastic pressing force to a variable disk of one or both input and output pulleys simply and with light weight, and the elastic force of an elastic member.
The common object of the present invention is achieved by a continuously variable transmission, wherein in order to secure a torque of one pulley out of input and output pulleys for effecting the constant horse power transmission, an operating unit always supplies and controls the elastic force generated by compressing in series an elastic device by a compressing device to the other pulley and variably presses and controls said other pulley in response to an instruction of output rotating speed or speed ratio, and a controlling device controls the shaft torque of said one pulley indirectly via a belt by operation of the
Charles Marcus
Rothwell Figg Ernst & Manbeck
Tokyo Automatic Machinery Co., Ltd.
LandOfFree
Continuously variable transmission does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Continuously variable transmission, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Continuously variable transmission will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3177963