Hydraulic speed control arrangement for an infinitely variable transmission

• US 4,501,172 A
• Filed: 08/16/1982
• Issued: 02/26/1985
• Est. Priority Date: 08/16/1982
• Status: Expired due to Term

• Current Assignee: NSK Limited
• Original Assignee: Excelermatic Inc.
• Inventors: Kraus, Charles E.
• Primary Examiner(s): Braun, Leslie A.
• Assistant Examiner(s): NOT, DEFINED
• Application Number:
  US06/408,422
• Time in Patent Office: 925 Days
• Field of Search: 74/867, 74/868, 74/752 C, 74/687, 74/731, 74/190.5, 74/793, 74/872, 137/47, 137/58, 137/486, 137/117, 137/116.3
• US Class Current: 74/731.1
• CPC Class Codes: F16H 59/40 Output shaft speed
• CPC Class Codes: F16H 61/0021 Generation or control of line pressure
• CPC Class Codes: F16H 61/6646 controlling shifting exclusively as a function of speed
• CPC Class Codes: Y10T 74/19153 Condition responsive control

Abstract

A constant output speed control arrangement for an infinitely variable transmission whose ratio of transmission is controllable by a hydraulic control fluid wherein the transmission output shaft has a fluid displacement pump associated therewith and connected to a control valve structure including a piston disposed in a cylinder and being movable by the control fluid from the pump against the force of a spring with a control passage extending through the piston and a control opening in the cylinder providing communication with a hydraulic ratio control structure in the transmission, the control opening being so arranged relative to the piston that the control opening is closed by the piston when the piston is moved against the spring force by an excess amount of control fluid supplied by the pump so as to cause a transmission ratio change for a decrease of the transmission output shaft, and the control opening is opened by the piston when the piston is returned by the spring for admitting an increased amount of control fluid to the transmission thereby causing an increase in the transmission output shaft speed.

Claims

1. A constant output speed control arrangement for an infinitely variable transmission whose transmission ratio is controllable by controlling the supply of hydraulic control fluid thereto, and which is adapted to be connected to a variable speed power source, said control arrangement comprising a displacement pump associated with the output shaft of said transmission so as to supply a control fluid flow proportional to the speed of the transmission output shaft, a transmission control valve structure including a cylinder having a piston movably disposed therein, said piston being biased in one direction by a spring arranged at one side thereof, means for supplying said control fluid from said displacement pump to said cylinder at the other side of said piston, a passage means providing communication between said one and said other side of said piston and having a flow control orifice disposed therein for permitting passage of a desired amount of control fluid, said cylinder having a control opening arranged at said one side of said portion and in communication with said transmission for controlling its transmission ratio, said control opening being adapted to be closed by the piston when said piston is moved by a larger than desired amount of control fluid against the force of said spring for changing the transmission ratio so as to reduce transmission output shaft speed and said control opening, when being opened by said piston upon supply of less than said desired amount of control fluid, providing for the supply of control fluid to said transmission for a change of the transmission ratio so as to increase transmission output shaft speed, and a relief valve structure associated with said valve for maintaining within said valve a predetermined fluid pressure sufficient to operate the speed change control mechanism of said infinitely variable transmission.

2. An arrangement as claimed in claim 1, wherein said cylinder is a passage extending through the valve housing and having said control fluid supply means connected to one end thereof and a control screw threaded into the opposite end thereof with said piston being disposed therebetween and a control spring disposed between said piston and said control screw.

3. An arrangement as claimed in claim 2, wherein said means providing communication between said one and said other side of the piston is a passage extending through said piston and including a control orifice.

4. An arrangement as claimed in claim 3, wherein said control orifice is an opening formed in the face of said piston and tapered outwardly in the direction of fluid flow therethrough.

5. An arrangement as claimed in claim 1, wherein a fluid discharge port is formed in the housing in communication with the cylinder space between said piston and said control screw, said outlet port having said relief valve associated therewith.