US-12618457-B2 - Double cam actuation system for CVT

US12618457B2US 12618457 B2US12618457 B2US 12618457B2US-12618457-B2

Abstract

A new scissor-ramp mechanism for a Continuously Variable Transmission (CVT) provides smooth transmission of variation to the width of the groove for the V-belt of the CVT. The scissor-ramp mechanism consists in driving rings that are coaxial, concentric to each other, and rotatable relative to one another, each having a driving abutting facet; and a driven ring having driven abutting facets. The driving abutting facets are adapted to abut against the driven abutting facets, with at least one abutting facet being provided by a helicoidal ramp. Rotating the driving rings relative to one another exerts a contacting section of abutting facets to migrate over the ramp, thereby changing the axial dimension of the scissor-ramp mechanism.

Inventors

David Levasseur
Samuel Paul
Pierre Lebel
Pascal THIBODEAU

Assignees

CVTECH-IBC INC.

Dates

Publication Date: 20260505
Application Date: 20241016

Claims (18)

1 . A scissor-ramp mechanism for a Continuously Variable Transmission (CVT), the scissor-ramp mechanism extending along a rotation axis, with the scissor-ramp mechanism being adapted for varying continuous its axial dimension, the scissor-ramp mechanism comprising: a first driving ring and a second driving ring that are coaxial, concentric to each other, and rotatable relative to one another around the rotation axis, each one of the first driving ring and the second driving ring comprising a driving abutting facet; and a driven ring rotatable around the rotation axis, the driven ring comprising driven abutting facets; wherein the driving abutting facets are adapted to abut against the driven abutting facets, wherein at least one abutting facet among the driving abutting facets and the driven abutting facets is provided by a first helicoidal ramp, wherein rotating the driving rings relative to one another exerts a contacting section of the abutting facet provided by the first helicoidal ramp to migrate thereover, thereby changing the axial dimension of the scissor-ramp mechanism, and wherein the scissor-ramp mechanism is mounted to a body and to a shaft rotatable relative to the body with the shaft axially coupled to the body, wherein one of the driving rings is fixedly mounted to the body.
2 . The scissor-ramp mechanism of claim 1 , wherein the driven ring is free of a mechanic coupling to the driving rings.
3 . The scissor-ramp mechanism of claim 1 , wherein rotating the driving rings relative to one another of a first number of degrees exerts a rotation of the driven ring of a second number of degrees that is less than the first number of degrees.
4 . The scissor-ramp mechanism of claim 1 , further comprising a second helicoidal ramp, wherein each one of the first helicoidal ramp and the second helicoidal ramp has a rate of an axial extent per degree of rotation, and wherein rotating the driving rings relative to one another exerts a variation of the axial dimension of the scissor-ramp mechanism per degree of rotation of the driving rings relative to one another that is lower than the maximum of the rates of the first helicoidal ramp and of the second helicoidal ramp.
5 . The scissor-ramp mechanism of claim 1 , wherein the first driving ring comprises the first helicoidal ramp and the second driving ring comprises a second helicoidal ramp.
6 . The scissor-ramp mechanism of claim 5 , wherein the first helicoidal ramp extends in a first spin direction, and wherein the second helicoidal ramp extends in a second spin direction opposed to the first spin direction.
7 . The scissor-ramp mechanism of claim 1 , wherein the first driving ring comprises the first helicoidal ramp and a second helicoidal ramp, and wherein the first helicoidal ramp and the second helicoidal ramp extend in a first spin direction, and wherein the first helicoidal ramp and the second helicoidal ramp are offset from one another of a number of degrees that is greater than zero (0).
8 . The scissor-ramp mechanism of claim 1 , wherein the first helicoidal ramp has a constant rate of an axial extent per degree of rotation between a first position and a second position, wherein the second position is axially distant to the first position of at least 75% of a maximum variation of the axial dimension of the scissor-ramp mechanism between an extended-most position and a compact-most position.
9 . The scissor-ramp mechanism of claim 1 , wherein the abutment facets comprises a roller.
10 . The scissor-ramp mechanism of claim 1 , wherein the driven ring comprises an outer-ring section and an inner-ring section each comprising an helicoidal axial face, wherein the helicoidal axial face of the outer-ring section comprises a first one of the abutting facets of the driven ring and the helicoidal axial face of the inner-ring section comprises a second one of the abutting facets of the driven ring.
11 . The scissor-ramp mechanism of claim 10 , wherein the abutting facet of the inner-ring section and the abutting facet of the outer-ring section are offset relative to one another of a number of degrees greater than zero (0) around the rotation axis.
12 . The scissor-ramp mechanism of claim 10 , wherein the helicoidal axial face of the outer-ring section comprises a clearance-providing section in which the helicoidal axial face provides a contact-free section relative to driving rings, wherein the contact-free section remains when the abutting facets of the driving rings abuts against the abutting facets of the driven ring.
13 . A scissor-ramp mechanism for a Continuously Variable Transmission the scissor-ramp mechanism extending along a rotation axis, with the scissor-ramp mechanism being adapted for varying continuous its axial dimension, the scissor-ramp mechanism comprising: a first driving ring and a second driving ring that are coaxial, concentric to each other, and rotatable relative to one another around the rotation axis, each one of the first driving ring and the second driving ring comprising a driving abutting facet; and a driven ring rotatable around the rotation axis, the driven ring comprising driven abutting facets: wherein the driving abutting facets are adapted to abut against the driven abutting facets, wherein at least one abutting facet among the driving abutting facets and the driven abutting facets is provided by a first helicoidal ramp, wherein rotating the driving relative to one another exerts a contacting section of the abutting face vided by the first helicoidal ramp to migrate thereover, thereby changing the axial dimension of the scissor-ramp mechanism, wherein the driven ring comprises an outer-ring section and an inner-ring section each comprising an helicoidal axial face, wherein the helicoidal axial face of the outer-ring section comprises a first one of the abutting facets of the drive in ring and the helicoidal axial face of the inner-ring section comprises a second one of the abutting facets of the driven ring, and wherein the driven ring is made of a single component.
14 . A scissor-ramp mechanism for a Continuously Variable Transmission (CVT), the scissor-ramp mechanism extending along a rotation axis, with the scissor-ramp mechanism being adapted for varying continuous its axial dimension, the scissor-ramp mechanism comprising: a first driving ring and a second driving ring that are coaxial, concentric to each other, and rotatable relative to one another around the rotation axis, each one of the first driving ring and the second driving ring comprising a driving abutting facet; and a driven ring rotatable around the rotation axis, the driven ring comprising driven abutting facets, wherein the driving abutting facets are adapted to abut against the driven abutting facets, wherein at least one abutting facet among the driving abutting facets and the driven abutting facets is provided by a first helicoidal ramp, wherein rotating the driving rings relative to one another exerts a contacting section of the abutting facet provided by the first helicoidal ramp to migrate thereover, thereby changing the axial dimension of the scissor-ramp mechanism, wherein the driven ring comprises an outer-ring section and an inner-ring section each comprising an helicoidal axial face, wherein the helicoidal axial face of the outer-ring section comprises a first one of the abutting facets of the driven ring and the helicoidal axial face of the inner-ring section comprises a second one of the abutting facets of the driven ring, wherein the scissor-ramp mechanism is adapted to continuously adjust between a compact-most position and an extended-most position, and wherein the scissor-ramp mechanism further comprises biasing means biasing the scissor-ramp mechanism towards the compact-most position.
15 . The scissor-ramp mechanism of claim 1 , further comprising a second helicoidal ramp, wherein each one of the driving rings comprises one of the helicoidal ramps, wherein the helicoidal ramps are extending in opposite spin directions, and wherein rotating the driving rings relative to one another exerts the abutting facets of the driven ring to slide simultaneously over the helicoidal ramps of the driving rings.
16 . A CVT comprising the scissor-ramp mechanism of claim 1 , the CVT comprising an axially-fixed sheave, and an axially-movable sheave coaxially mounted to the scissor-ramp mechanism, wherein the scissor-ramp mechanism is adapted to push against the axially-movable sheave to adjust a width of a V-shaped groove between the sheaves.
17 . The CVT of claim 16 , further comprising an actuator assembly coupled to the scissor-ramp mechanism through the scissor-ramp mechanism shaft, wherein the actuator assembly is adapted for exerting a rotation of the driving rings relative to one another.
18 . A method of operating a Continuously Variable Transmission (CVT) having a groove width constrained along a rotation axis, the method comprising: a) providing a scissor-ramp mechanism adapted to constrain the groove width, comprising: i) driving rings that are coaxial, concentric to each other, and rotatable relative to one another around the rotation axis, each one of the driving rings comprising a driving abutting facet; and ii) a driven ring rotatable around the rotation axis, the driven ring comprising driven abutting facets, wherein at least one abutting facet among the driving abutting facets and the driven abutting facets is provided by a first helicoidal ramp; b) rotating the driving rings one relative to another in a first spin direction through which the driving abutting facets are abutting against the driven abutting facets with a contacting section of the abutting facet provided by the first helicoidal ramp being exerted to migrate thereover in a first migrating direction, thereby increasing an axial dimension of the scissor-ramp mechanism and thereby causing the groove width to decrease, c) providing a biasing means adapted to bias the driven ring towards the driving rings; and d) rotating the driving rings one relative to another in a second spin direction such that the contacting section being exerted to migrate thereover in a second migrating direction by the biasing means, thereby decreasing the axial dimension of the scissor-ramp mechanism causing the groove width to increase.

Description

CROSS-REFERENCE TO RELATED APPLICATION This application relates to and is a provisional application claiming priority under 35 U.S.C. § 119(e) and 37 C.F.R. § 1.78(a) for a priority claim to earlier-filed provisional applications, U.S. patent application Ser. No. 63/544,606, filed 2023 Oct. 17 under 35 U.S.C. § 111, entitled DOUBLE CAM ACTUATION SYSTEM FOR CVT, and U.S. patent application Ser. No. 63/559,688, filed 2024 Feb. 29 under 35 U.S.C. § 111, entitled DOUBLE RING ACTUATION SYSTEM FOR CVT, the specifications of which are hereby incorporated herein by reference in their entireties. BACKGROUND (a) Field The subject matter disclosed generally relates to a double ring actuation systems for CVT. More particularly, the subject matter disclosed relates to an electrically assisted CVT with a double ring mechanism. (b) Related Prior Art Transmissions are mechanisms that transform the speed and torque in vehicles using gears, belts, or other drive components. Most transmission designs use discrete speed ratios: low ratios for acceleration, hill climbing, and heavy hauling, and high ratios for higher-speed travel. They use multiple parallel gear sets between input and output shafts. By sequentially changing which gear set carries the loads between the shafts, the speed ratio between the input and output shafts is altered. Transmissions have also been designed that are continuously variable (CVTs). These generally use friction to transfer load from an input shaft to an output shaft. By altering the radial position of friction rollers, belts, or other components, the speed ratio is changed. Mos/t current CVTs rely upon fixed-design mechanical or hydraulic actuation that cannot be easily changed to respond to differing demands, such as varying vehicle cargo loads and operator performance demands. Many solution have been tried to improve flexibility, response time, force requirements, etc. with variable efficiency. One solution was developed by Steven BENSON, and published as a TORQUE RESPONSIVE ACTUATION DEVICE, publication U.S. Pat. No. 5,720,681 A. BENSON describes a torque responsive actuation device with bearings that travel along individual tracks of track sections of a helix or cam cone, with either opposing bearing or track surface to have a convex surface with a greatest diameter of the convex surface at the surface center so as to provide a point contact between the bearing surfaces that will remain centered during travel of the one surface over the other. Another solution was developed by PIAGGIO & C SPA, and published as a CONTINUOUSLY VARIABLE TRANSMISSION DEVICE WITH DEVICE FOR VARYING THE TRANSMISSION CURVE, publication U.S. Pat. No. 11,105,408 B2. PIAGGIO describes a continuously variable transmission device that includes a drive pulley, and a cam system operating between a fixed bushing and a mobile bushing configured for transmitting the rotation between the fixed bushing and the mobile bushing and for opposing the movement towards each other of the active surfaces. A driven cam portion of the mobile bushing and a drive cam portion of the fixed bushing respectively having a driven cam profile and a drive cam profile. The described mobile bushing comprises a main wall, annular with respect to the axis of rotation (X), having an inner surface which delimits a housing compartment, and the driven cam portion protrudes radially internally from said inner surface; and the drive cam portion of the fixed bushing is suitable to penetrate axially in the housing compartment of the mobile bushing. As demonstrated by the above references, and nevertheless the improvements provided by these references, needs remain in the art for CVT actuation systems improvements. Accordingly, a need has been felt for a solution aimed at a CVT actuation system that is more flexible and adaptable than the current state of technology. SUMMARY According to an embodiment, there is provided a scissor-ramp mechanism that is adapted to provide pressure over a CTV pulley wherein contact sections are migrating over ramps as the scissor-ramp mechanism is actuated. In some aspects, the description herein relates to a scissor-ramp mechanism for a Continuously Variable Transmission, the scissor-ramp mechanism extending along an axis, with the scissor-ramp mechanism being adapted for varying continuous its axial dimension, the scissor-ramp mechanism including a first driving ring and a second driving ring that are coaxial, concentric to each other, and rotatable relative to one another around the axis, each one of the first driving ring and the second driving ring including a driving abutting facet; and a driven ring rotatable around the axis, the driven ring including driven abutting facets; wherein the driving abutting facets are adapted to abut against the driven abutting facets, wherein at least one abutting facet among the driving abutting facets and the driven abutting facets is provided by a first helicoidal ramp, and wherein rotatin