A structure is achieved capable of ensuring excellent transmission efficiency while preventing the occurrence of gross slipping at traction portions.

A pressing device 9 rotationally drives a cam disk 21 by a pressing force adjusting motor 23, which causes an annular roller element 6a of a pair of annular roller elements 6a, 6b to displace in the axial direction. A controller 31, by adjusting the rotational drive of the pressing force adjusting motor 23, adjusts the surface pressure at the traction portions between rolling surfaces 16 of planetary rollers 7 and an inner-diameter side rolling contact surface 5 of an input shaft 3 and outer-diameter side rolling contact surfaces 12a, 12b of the pair of annular roller elements 6a, 6b to a target value.

An electric actuator includes: a motor section (5) including a stator (51) and a rotor (52); a driving-source output shaft (6), which is arranged on a radially inner side of the rotor, and is configured to output rotation of the rotor; and a speed reducer (2) connected to the driving-source output shaft. The driving-source output shaft (6) is hollow, and the speed reducer (2) includes a planetary-traction-drive speed reducer.

An auxiliary machine-driving device has a first idler roller disposed between an engine roller and a first rotating roller; a second idler roller disposed between the first rotating roller and a second rotating roller; a third idler roller disposed between the second rotating roller and the engine roller; and a linking mechanism driven by one actuator to switch the first idler roller between a state in which the first idler roller contacts the engine roller and the first rotating roller, and a state in which the first idler roller separates from the engine roller and the first rotating roller, and to switch at least one of the second and third idler rollers between a state in which the at least one roller contacts two rollers adjacent the at least one roller, and a state in which the at least one roller separates from the two rollers.

An auxiliary machine-driving device has a first idler roller disposed between an engine roller and a first rotating roller; a second idler roller disposed between the first rotating roller and a second rotating roller; a third idler roller disposed between the second rotating roller and the engine roller; and a linking mechanism driven by one actuator to switch the first idler roller between a state in which the first idler roller contacts the engine roller and the first rotating roller, and a state in which the first idler roller separates from the engine roller and the first rotating roller, and to switch at least one of the second and third idler rollers between a state in which the at least one roller contacts two rollers adjacent the at least one roller, and a state in which the at least one roller separates from the two rollers.

There is described a multistage friction/traction speed adapter. A first drive can include a plurality of free rollers orbiting around a sun element within a frame, transmitting their orbiting movement to guided rollers which do not contact the sun element or the frame. The guided rollers are driven in the orbiting movement and transmit the rotary movement to a carrier via corresponding pins which engage with the carrier. A second drive can include rollers having radial position variation which is prevented from being transmitted to the carrier by providing accommodation at the pin level, either by providing a bushing around the pins with a bore that is eccentric relative to its outer surface, either by engaging the pins into the carriers in portions thereof which are made more flexible. A friction/traction gear at an angle is also disclosed.

There is described a multistage friction/traction speed adapter. A first drive can include a plurality of free rollers orbiting around a sun element within a frame, transmitting their orbiting movement to guided rollers which do not contact the sun element or the frame. The guided rollers are driven in the orbiting movement and transmit the rotary movement to a carrier via corresponding pins which engage with the carrier. A second drive can include rollers having radial position variation which is prevented from being transmitted to the carrier by providing accommodation at the pin level, either by providing a bushing around the pins with a bore that is eccentric relative to its outer surface, either by engaging the pins into the carriers in portions thereof which are made more flexible. A friction/traction gear at an angle is also disclosed.

A multi-stage planetary roller power transmission device includes a high-speed power transmission mechanism including a first sun shaft, a first fixed ring, first planetary rollers disposed between the first sun shaft and the first fixed ring with a first negative clearance, first support shafts, and an annular first carrier into which the first support shafts are press-fitted; and a low-speed power transmission mechanism including a second sun shaft, a second fixed ring, second planetary rollers disposed between the second sun shaft and the second fixed ring with a second negative clearance, second support shafts, and an annular second carrier into which the second support shafts are press-fitted. A clearance amount of the first negative clearance and a clearance amount of the second negative clearance are equal to each other, and the number of the first planetary rollers is smaller than the number of the second planetary rollers.

The frictional roller reducer has an input shaft, an output shaft, a pair of annular roller elements, a plurality of planetary rollers, a carrier, a pressing device, and a controller. The pressing device rotationally drives a cam disk by a pressing force adjusting motor, which causes an annular roller element of the pair of annular roller elements to displace in the axial direction. The controller, by adjusting the rotational drive of the pressing force adjusting motor, adjusts the surface pressure at the traction portions between rolling surfaces of the planetary rollers and an inner-diameter side rolling contact surface of the input shaft and outer-diameter side rolling contact surfaces of the pair of annular roller elements to a target value.

The frictional roller reducer has an input shaft, an output shaft, a pair of annular roller elements, a plurality of planetary rollers, a carrier, a pressing device, and a controller. The pressing device rotationally drives a cam disk by a pressing force adjusting motor, which causes an annular roller element of the pair of annular roller elements to displace in the axial direction. The controller, by adjusting the rotational drive of the pressing force adjusting motor, adjusts the surface pressure at the traction portions between rolling surfaces of the planetary rollers and an inner-diameter side rolling contact surface of the input shaft and outer-diameter side rolling contact surfaces of the pair of annular roller elements to a target value.

Disclosed is an air pump for a fuel cell that utilizes a speed-reduction traction drive so that a low speed electric motor can be used to drive a high-speed rotodynamic compressor. The rotodynamic compressor is an efficient air pump, but operates at high speeds that would require a specialized high-speed electric motor. The speed-reduction traction drive couples to the compressor and provides a low-speed output that is connected to a lower speed electric motor.