Four-Position Shift Valve for Multi-Speed Transmission

The patent replaces the manual mechanical valve operation with an electronically controlled system. The operator interacts with electronic controls (buttons, switches, or touchscreens) that send signals to solenoid valves, which then control hydraulic fluid flow to shift mechanisms. This substitution eliminates the need for manual valve manipulation while maintaining hydraulic actuation, thereby improving ease of operation without significantly increasing overall system complexity.

The patent employs a dual-mode control system where the solenoid valves can operate in two states: electrically actuated mode during normal operation and hydraulically actuated mode during electrical failures. The system includes a fail-safe mechanism that detects electrical failures and automatically switches to hydraulic actuation of the solenoid valves, allowing them to be controlled by hydraulic pressure rather than electrical signals. This parameter change in the actuation mode ensures continued reliability during electrical failures while maintaining ease of operation under normal conditions.

The patent designs the shift valves to be multi-functional components that can control multiple gear ranges through a single valve mechanism. Each shift valve is configured with multiple ports and internal passages that allow it to direct hydraulic fluid to different shift mechanisms depending on its position. This universal design enables a single shift valve to perform the function of what would traditionally require multiple separate valves, thereby reducing device complexity while maintaining the adaptability to control various gear ranges including forward gears, reverse, and neutral.

The fourth shift valve incorporates a self-latching mechanism that automatically maintains its position during electrical failures without requiring external control signals. The valve design includes internal hydraulic latching features where fluid pressure differential across the valve spool creates a self-sustaining position once established. During normal operation, electrical signals control the valve position, but upon electrical failure, the hydraulic latching mechanism takes over and maintains the valve in its last commanded position, ensuring reliability while avoiding the need for complex additional control systems.