Hydraulic Park-By-Wire Shift Linkage for Reliable Park Engagement
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Solution Overview
Problem
Existing park systems in transmissions face challenges in efficiently and reliably braking the output shaft, particularly in transitioning between engaged and disengaged states, due to limitations in hydraulic fluid pressure control and mechanical linkage design.
Innovation Solution
A park system incorporating a park gear assembly, an actuator valve with a valve element translatable along a longitudinal axis, and an actuation linkage with a pivotally coupled plate and mount extension, utilizing distinct annular grooves and a locking pin to block valve element movement, and employing separate hydraulic fluid pressures for engaged and disengaged states, along with a position sensor and pressure control solenoids for precise control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a traditional mechanical linkage is used to connect the actuator to the park gear assembly, then the structure is simple, but the reliability of braking the output shaft is insufficient
Solution Approach 1:
The patent employs a hydraulic actuator valve with a valve element that translates axially in response to hydraulic fluid pressure. This hydraulic mechanism replaces traditional mechanical linkages, providing more reliable and controllable braking force application to the park gear assembly, thereby improving the reliability of output shaft braking while accepting increased system complexity.
2Measurement precision
If hydraulic fluid pressure is applied to the valve element to drive park system operation, then the park system can be controlled, but the precision of valve element positioning is insufficient
Solution Approach 1:
The patent incorporates a position sensor that generates a signal indicative of the valve element position. This feedback mechanism allows the control system to monitor and adjust hydraulic pressure to achieve precise valve element positioning, thereby improving measurement precision while accepting the added complexity of the pressure control system with feedback.
3Adaptability or versatility
If a single hydraulic pressure control system is used, then the system is simple, but the ability to distinguish between engaged and disengaged states is insufficient
Solution Approach 1:
The patent divides the pressure control system into separate pressure control solenoids for controlling engaged and disengaged states. This segmentation allows independent control of each state, improving the system's adaptability and versatility in managing park system operations while accepting the increased complexity of multiple pressure control solenoids.
4Stability of the object's composition
If the valve element is allowed to move freely along the longitudinal axis, then the operation is smooth, but the stability of valve position is insufficient
Solution Approach 1:
The patent employs a locking pin that can be positioned in annular grooves on the valve element to prevent its movement. This preliminary locking action ensures stable valve element positioning at critical points (engaged and disengaged states) while maintaining smooth operation during transitions, accepting the added complexity of the locking mechanism.
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
The system effectively resists or permits rotation of the output shaft by accurately controlling hydraulic fluid pressures and mechanical linkages, ensuring reliable operation in both engaged and disengaged states, enhancing the transmission's park mode functionality.
Implementation Method 1
The actuator valve may have a valve element axially translatable along a first longitudinal axis in response to one or more fluid pressures applied thereto
Implementation Method 2
The park system may include a first pressure control solenoid to supply a first hydraulic fluid pressure to the actuator valve and a second pressure control solenoid to supply a second hydraulic fluid pressure to the actuator valve
Data Source
AI summary
Transmissions, park systems, and methods of operating transmissions are disclosed. A transmission includes an input shaft to receive torque from a drive unit, an output shaft to transmit torque to a load, and a park system to selectively brake the output shaft. The park system includes a park gear assembly, an actuator valve, and an actuation linkage coupled between the actuator valve and the park gear assembly.