A primary clutch of a continuously variable transmission with a launch mechanism is provided. The primary clutch includes a central post, a fixed sheave assembly, a movable sheave assembly and a locking mechanism. The central post is configured to receive rotational torque from a motor. The fixed sheave assembly is statically mounted on the central post. The movable sheave assembly is mounted on the central post. The movable sheave assembly includes a movable sheave system that is configured to move axially on the central post towards the fixed sheave assembly as RPM of the primary clutch increase. The locking mechanism is configured and arranged to selectively prevent movement of the movable sheave system independent of the RPM of the primary clutch.

A primary clutch of a continuously variable transmission with a launch mechanism is provided. The primary clutch includes a central post, a fixed sheave assembly, a movable sheave assembly and a locking mechanism. The central post is configured to receive rotational torque from a motor. The fixed sheave assembly is statically mounted on the central post. The movable sheave assembly is mounted on the central post. The movable sheave assembly includes a movable sheave system that is configured to move axially on the central post towards the fixed sheave assembly as RPM of the primary clutch increase. The locking mechanism is configured and arranged to selectively prevent movement of the movable sheave system independent of the RPM of the primary clutch.

The present invention relates to relates to an improvement of a dividing wall for a primary pulley in a belt-type continuously variable transmission. It is an object of the present invention to obtain a desired strength characteristic without performing a soft nitriding treatment and achieve cost reduction. A hydraulic pressure chamber is formed between the dividing wall and the movable sheave, and the dividing wall comprises a small-diameter annular disc portion 32 extended from the central cylinder portion 30, which is attached to a rotational shaft, in a radial direction. In the small-diameter annular disc portion 32, a connecting portion which is connected to an intermediate body portion 34 is a bent portion 38 which is bent at substantially 90 [deg]. In a cross-section of an inner peripheral surface of the bent portion 38, the inner peripheral surface of the bent portion 38 is constituted by an inner radius side arc 40-1 whose origin position is O.sub.1 and curvature radius is R.sub.1, an outer radius side arc 40-2 whose origin position is O.sub.2, which is a different position from the origin position O.sub.1 of the inner radius side arc 40-1, and curvature radius is R.sub.2, which is a different value from the curvature radius R.sub.1 of the inner radius side arc 40-1, and an intermediate portion 40-3 that the inner radius side arc 40-1 is smoothly connected to the outer radius side arc 40-2. By adopting the above shape, when a load is applied to the dividing wall, a stress value at a concave surface 40 can be reduced, and desired durability can be obtained without performing the soft nitriding treatment and achieve cost reduction.

The present invention relates to relates to an improvement of a dividing wall for a primary pulley in a belt-type continuously variable transmission. It is an object of the present invention to obtain a desired strength characteristic without performing a soft nitriding treatment and achieve cost reduction. A hydraulic pressure chamber is formed between the dividing wall and the movable sheave, and the dividing wall comprises a small-diameter annular disc portion 32 extended from the central cylinder portion 30, which is attached to a rotational shaft, in a radial direction. In the small-diameter annular disc portion 32, a connecting portion which is connected to an intermediate body portion 34 is a bent portion 38 which is bent at substantially 90 [deg]. In a cross-section of an inner peripheral surface of the bent portion 38, the inner peripheral surface of the bent portion 38 is constituted by an inner radius side arc 40-1 whose origin position is O.sub.1 and curvature radius is R.sub.1, an outer radius side arc 40-2 whose origin position is O.sub.2, which is a different position from the origin position O.sub.1 of the inner radius side arc 40-1, and curvature radius is R.sub.2, which is a different value from the curvature radius R.sub.1 of the inner radius side arc 40-1, and an intermediate portion 40-3 that the inner radius side arc 40-1 is smoothly connected to the outer radius side arc 40-2. By adopting the above shape, when a load is applied to the dividing wall, a stress value at a concave surface 40 can be reduced, and desired durability can be obtained without performing the soft nitriding treatment and achieve cost reduction.

The control mode is switched between a first control mode configured to control the speed change pump based on an actual speed ratio being an actual speed ratio of the variator, and a second control mode configured to control the speed change pump based on an actual working pressure being an actual working pressure of the variator. In the first control mode, the actual speed ratio is calculated based on a detected value of a vehicle speed; and the speed change pump is controlled to cause the actual speed ratio to approach the target speed ratio. In the second control mode, the actual working pressure is detected and the speed change pump is controlled to cause the actual working pressure to approach a target working pressure corresponding to the target speed ratio. In a situation or a condition where the detection accuracy of the vehicle speed by the vehicle speed sensor decreases, the control mode is switched from the first control mode to the second control mode.

A CVT acceleration control method applied to a CVT-mounted vehicle including an accelerator position sensor, a vehicle speed sensor, a driving pulley rotation sensor and a driven pulley rotation sensor that is configured to detect a rotation speed of a driven pulley and to output a corresponding signal, a CVT operation portion and a controller, the CVT acceleration control method, may include determining, by the controller, whether a current vehicle driving state satisfies a predetermined starting control condition, monitoring, by the controller, a current driving pulley rotation speed change, determining, by the controller, whether the current vehicle driving state satisfies a predetermined trigger condition, setting, by the controller, a target driving pulley rotation speed change, and controlling, by the controller, the operation of the CVT operation portion such that the current driving pulley rotation speed change converges to the target driving pulley rotation speed change.

A CVT acceleration control method applied to a CVT-mounted vehicle including an accelerator position sensor, a vehicle speed sensor, a driving pulley rotation sensor and a driven pulley rotation sensor that is configured to detect a rotation speed of a driven pulley and to output a corresponding signal, a CVT operation portion and a controller, the CVT acceleration control method, may include determining, by the controller, whether a current vehicle driving state satisfies a predetermined starting control condition, monitoring, by the controller, a current driving pulley rotation speed change, determining, by the controller, whether the current vehicle driving state satisfies a predetermined trigger condition, setting, by the controller, a target driving pulley rotation speed change, and controlling, by the controller, the operation of the CVT operation portion such that the current driving pulley rotation speed change converges to the target driving pulley rotation speed change.

A spider is screwed to a drive shaft, includes a first screw that advances in one direction of an axial direction of the drive shaft when the spider rotates relative to the drive shaft in one direction of a circumferential direction, and is fastened to the drive shaft by the first screw. A nut is screwed to the drive shaft, includes a second screw that advances in the other direction of the axial direction of the drive shaft when the nut rotates relative to the drive shaft in one direction of the circumferential direction, and is fastened to the drive shaft by the second screw.

A spider is screwed to a drive shaft, includes a first screw that advances in one direction of an axial direction of the drive shaft when the spider rotates relative to the drive shaft in one direction of a circumferential direction, and is fastened to the drive shaft by the first screw. A nut is screwed to the drive shaft, includes a second screw that advances in the other direction of the axial direction of the drive shaft when the nut rotates relative to the drive shaft in one direction of the circumferential direction, and is fastened to the drive shaft by the second screw.

A continuously variable transmission, a vehicular powertrain that includes a continuously variable transmission and a method of limiting belt slippage in a continuously variable transmission in a vehicle. The continuously variable transmission includes a pulley assembly, shafts, a clutch and hydraulic system. The hydraulic system is cooperative with both the clutch and the pulley assembly so that hydraulic pressures and associated clamping forces sent to both allow the clutch to preferentially absorb any driving load coming from the axle and wheels that is in excess of the normal load experienced at the continuously variable transmission. This in turn means that any additional load that would ordinarily cause slippage in the belt is instead experienced by the clutch. By providing such a clutch, the pump of the hydraulic system does not need to be oversized in order to provide excess clamping force, as any excess load experienced by the shaft that is coupled to the wheels of the vehicle will be taken up by slippage in the clutch so that slippage-related wear to the belt is avoided.