Transmission Actuator Fork Velocity Control
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Solution Overview
Problem
In vehicular transmissions, precise control of the actuator fork's velocity during the pre-synchronization phase is crucial to prevent the sleeve force from exceeding the breakaway force, ensuring consistent and predictable shifts, as excessive force can lead to premature release of the strut assembly from the sleeve, causing noise, shift roughness, and inconsistency.
Innovation Solution
A method is implemented to control the actuator fork's velocity within a predetermined range by adjusting the fluid pressure applied to the actuator piston, using a controller that compares the actual fork velocity to a target velocity and adjusts the pressure accordingly, ensuring the sleeve force remains below the breakaway force, thereby maintaining the strut assembly's retention and proper synchronization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the fluid pressure applied to the actuator piston is increased to increase the velocity of the actuator fork, then the shift time is reduced and productivity is improved, but the sleeve force exerted on the ball plunger exceeds the breakaway force, causing the strut assembly to be prematurely released from the sleeve, resulting in noise, shift roughness, and inconsistency
Solution Approach 1:
The patent applies parameter changes by dynamically adjusting the fluid pressure applied to the actuator piston based on the detected velocity of the actuator fork. The controller modifies the pressure parameter in real-time to maintain the fork velocity within a predetermined range that ensures the sleeve force remains below the breakaway force of the ball plunger, thereby preventing premature release of the strut assembly while still achieving efficient shift times.
2Reliability
If the velocity of the actuator fork is controlled below the breakaway velocity to prevent premature release of the strut assembly, then the reliability and consistency of shifts are improved, but the shift time increases and productivity decreases
Solution Approach 1:
The patent implements dynamics by continuously monitoring the velocity of the actuator fork and dynamically adjusting the fluid pressure in response to the detected velocity. This closed-loop control system allows the system to operate at optimal velocities that maintain reliability while minimizing shift time, adapting the pressure in real-time rather than using a fixed conservative velocity limit.
Solution Approach 2:
The patent employs feedback control by detecting the actual velocity of the actuator fork and using this information to adjust the fluid pressure applied to the actuator piston. The controller receives velocity feedback and modifies the pressure accordingly to maintain the fork velocity within the predetermined range, ensuring both reliability and productivity are optimized simultaneously.
3Stability of the object's composition
If the fluid pressure is continuously adjusted to maintain the fork velocity within a predetermined range, then the shift quality and homogeneity are improved, but the device complexity increases due to the need for velocity detection and continuous pressure control
Solution Approach 1:
The patent applies self-service by enabling the control system to automatically detect the fork velocity and adjust the fluid pressure without requiring external intervention. The controller autonomously monitors the velocity parameter and modifies the pressure accordingly, making the system self-regulating and reducing the need for complex external control mechanisms while maintaining consistent shift quality.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach ensures consistent and predictable shifts by maintaining the actuator fork's velocity below the breakaway velocity, preventing premature release of the strut assembly and ensuring smooth synchronization, thus enhancing shift quality and reducing wear.
Implementation Method 1
The actuator forks may be controlled, for example, by a pressure solenoid that applies a fluid pressure to a first side of an actuator piston
Implementation Method 2
The ball plunger is characterized by a breakaway force, such that when a sleeve force exerted on the ball plunger by the sleeve exceeds the breakaway force, the ball plunger is released from the detent
Implementation Method 3
This rotating frictional contact results in the blocker ring indexing prior to the sleeve contacting it
Data Source
AI summary
A method and system for controlling movement of an actuator fork of a transmission through a pre-synchronization phase of a synchronization event at a pre-synchronization fork velocity includes adjusting the level of fluid pressure applied to an actuator operatively attached to the actuator fork to control the pre-synchronization fork velocity within a predetermined range of a velocity target. The method determines, via a controller, the fork velocity during the pre-synchronization phase of a current synchronization event, compares the determined fork velocity to a velocity target, and adjusts the pressure level of fluid applied to an actuator piston of the actuator to control the velocity of the actuator fork within a predetermined range defined by the velocity target during a subsequent pre-synchronization phase. The velocity target may be defined for a shift type, such as a fast or slow shift, where the shift type is determined by the controller.