Variable speed, belt driven transmission system, speed sensing driver pulley and method

• US 4,493,221 A
• Filed: 01/12/1983
• Issued: 01/15/1985
• Est. Priority Date: 01/12/1983
• Status: Expired due to Term

• Current Assignee: Gates Corporation The
• Original Assignee: Gates Rubber Company (Gates Corporation The)
• Inventors: Stieg, Richard F., Juergens, Tristan, Dolan, John P., Worley, W. Spencer
• Primary Examiner(s): Bonck, Rodney H.
• Assistant Examiner(s): NOT, DEFINED
• Application Number:
  US06/457,338
• Time in Patent Office: 734 Days
• Field of Search: 474/11, 474/12, 474/13, 474/14, 474/46, 74/856, 74/861, 74/862
• US Class Current: 474/14
• CPC Class Codes: F16H 61/66245 using purely mechanical sensing or control means

Abstract

A method for shifting a transmission with a predominantly mechanical speed sensing actuator to within a 10 percent shifting zone around a chosen operating line on an engine rpm/torque map by matching the force balance of the driver pulley to a force balance on the driven pulley.

A variable speed belt drive transmission system with a predominantly mechanical speed sensing driver pulley and a torque sensing driven pulley that responds to an operating line, monotonic in torque having a slope from about 0.004 lb-ft/rpm to about 0.060 lb-ft/rpm where the driver pulley has an actuator that controls speed for a chosen torque value. The actuator has at least one centrifugal weight connected to an end of a torque producing spring to wind the spring. A second end of the spring is operatively connected through an articulated linkage to a movable half of the pulley such that the generated axial force is not directly proportional to square of the speed.

Claims

1. A method for operating a driver pulley of a belt driven transmission in conjunction with an engine characterized by charted interrelationships between engine speed, engine torque and brake specific fuel consumption (BSFC);

the transmission of the type with a driven pulley having axially separable pulley halves responsively operable to axial forces variable with engine speed for closing the driver pulley halves together;

a V-belt entrained by the driver and driven pulleys;

the driven pulley axial forces and driven axial forces cooperatively causing variable belt tensions for transmitting predetermined power loads between the driver and driven pulleys from (1) a maximum (speed down) ratio where the driver pulley halves are axially separated to a full open position and the driven pulley halves are positioned axially together to a full closed position by means of an actuator to (2) a minimum (speed up) ratio where the driver pulley halves are axially together to a full closed position and the driven pulley halves are axially separated to a full open position;

comprising the steps of;

selecting a desired operating line for the transmission from the charted engine interrelationships where the line is monotonic in torque and has a slope from about 0.004 lb.-ft/rpm to about 0.060 lb.-ft/rpm;

determining the maximum torque at the driver pulley;

determining a family of driven pulley axial forces based on the maximum torque at the driver pulley;

determining a family of required driver pulley axial forces for traction ratio equilibrium of the driver and driven pulleys at selected torques on the operating line;

determining the speeds at which driver pulley axial forces for equilibrium are required to meet the selected torques on the operating line;

providing the required driver pulley axial forces by means of a torsional spring with a centrifugal weight attached to one end of the spring and an articulated linkage operatively interconnected to the other end of the torsional spring, the axial forces provided by winding the torsional spring and biasing the axial force to close the driver pulley.

2. The method as claimed in claim 1 and further including the step of increasing the axial force to close the driver pulley by means of a secondary centrifugal weight operatively connected directly to the articulated linkage.

3. A variable speed pulley comprising:

a rotatable shaft;

a fixed pulley half that is coaxial and fixedly attached to rotate with said shaft;

a movable pulley half that is coaxial with and axially reciprocative along said shaft;

at least one centrifugal weight;

means for supporting the centrifugal weight to rotate with the shaft and pivot;

an articulated linkage;

means for connecting the articulated linkage to the movable pulley half; and

a torque producing spring having a first end operatively connected to the centrifugal weight and a second end operatively connected to the articulated linkage.

4. The variable speed pulley as claimed in claim 3 wherein a secondary centrifugal weight is attached to the articulated linkage.

5. The variable speed pulley as claimed in claim 3 wherein torque producing spring is a volutely wound clock spring.