Toroidal-type continuously variable transmission

• US 20040092359A1
• Filed: 08/01/2003
• Published: 05/13/2004
• Est. Priority Date: 08/02/2002
• Status: Active Grant

• Current Assignee: NSK Limited
• Original Assignee: NSK Limited
• Inventors: Inoue, Eiji, Imanishi, Takashi
• Granted Patent: US 7,303,503 B2
• Time in Patent Office: Days
• US Class Current: 476/10
• CPC Class Codes: F16H 2037/0886 with switching means, e.g. to change ranges
• CPC Class Codes: F16H 37/086 CVT using two coaxial friction members cooperating with at least one intermediate friction member
• CPC Class Codes: F16H 61/6649 characterised by the means for controlling the torque transmitting capability of the gearing

Abstract

A toroidal-type continuously variable transmission, has first and second disks respectively including inner surfaces; power rollers interposed for transmitting power; a pressing device for pressing the first disk toward the second disk; a main oil pressure control unit for non-electrically detecting the power for setting, as a target value, an oil pressure necessary for the pressing device when a transmission ratio between the first and second disks is a transmission ratio requiring a maximum pressing force, and increase the target value as the pressing force increases; an oil pressure correcting apparatus for electrically finding a necessary value of the oil pressure, the necessary value corresponding to the optimum value of pressing force generated by the pressing device, and also for introducing an oil pressure of a value into the pressing device, the oil pressure of the value being obtained by subtracting a correction value from the target value.

Claims

1. A toroidal-type continuously variable transmission, comprising:

first and second disks respectively including inner surfaces and disposed so as to be concentric with each other and rotated with respect to each other;

a plurality of power rollers interposed between and held by the mutually facing inner surfaces of the first and second disks for transmitting power between the first and second disks;

a pressing device of an oil pressure type for pressing the first disk toward the second disk;

a main oil pressure control unit for non-electrically detecting the force to be transmitted between the first and second disks, the main oil pressure control setting, as a target value, an oil pressure necessary for the pressing device to generate a pressing force necessary when a transmission ratio between the first and second disks is a transmission ratio requiring a maximum pressing force, and increase the target value as the pressing force increases; and

,

an oil pressure correcting apparatus for electrically finding a necessary value of the oil pressure, the necessary value corresponding to the optimum value of such pressing force to be generated by the pressing device as to vary according to the transmission ratio between the first and second disks, and also for introducing an oil pressure of a value into the pressing device, the oil pressure of the value being obtained by subtracting a correction value, which is a difference between the necessary value and the target value, from the target value.

2. A toroidal-type continuously variable transmission as set forth in claim 1, further comprising:

a support member swingable and shiftable about a pivot shaft in transmission with the power rollers rotatably supported; and

,

an actuator of an oil pressure type including a cylinder and a piston fitted into the cylinder and shifting the support member in the axial direction of the pivot shaft in accordance with supply and exclusion of the pressure oil,

wherein the force to be transmitted between the first and second disks is detected in accordance with a difference between oil pressures in a pair of oil pressure chambers existing within the cylinder on the two sides of the axial direction of the piston.

3. A toroidal-type continuously variable transmission as set forth in claim 1, wherein an operation device constituting the oil pressure correcting apparatus finds a correction signal according to the transmission ratio and the temperature of lubricating oil existing in the interior of the toroidal-type continuously variable transmission and the rotation speed of a drive source, and, in accordance with the correction signal, the correction value of the oil pressure is obtained by opening and closing an electromagnetic valve in accordance with the correction signal.

4. A toroidal-type continuously variable transmission as set forth in claim 2, wherein an operation device constituting the oil pressure correcting apparatus finds a correction signal according to the transmission ratio and the temperature of lubricating oil existing in the interior of the toroidal-type continuously variable transmission and the rotation speed of a drive source, and, in accordance with the correction signal, the correction value of the oil pressure is obtained by opening and closing an electromagnetic valve in accordance with the correction signal to thereby obtain.