Hybrid Park Lock System Electromechanical Actuation
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Solution Overview
Problem
Existing park lock systems in hybrid electric vehicles face issues such as the lock ball becoming lodged, preventing disengagement from out-of-park mode, and hydraulic systems lacking sufficient pressure to adjust the servo piston and lock ball, especially in hybrid electric vehicles without a hydraulic system.
Innovation Solution
A park lock system that includes a park rod, a slideable element with a slot, a pivotable pawl, a cam engaged with the pawl, and a solenoid electromechanically coupled to the cam, allowing the motor to adjust the park rod position and the solenoid to lock the transmission into out-of-park mode using an electrical system, eliminating the need for a hydraulic system.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a hydraulic system is used to adjust the servo piston and lock ball, then the park lock system can achieve reliable engagement, but the system becomes too complex and cannot generate sufficient hydraulic pressure in hybrid electric vehicles
Solution Approach 1:
The patent extracts and removes the hydraulic system from the park lock mechanism, replacing it with a direct electromechanical actuation system. The servo piston and lock ball are eliminated, leaving only the essential components (actuator, park rod, park pawl) needed for reliable park lock engagement, thereby reducing complexity while maintaining functionality
Solution Approach 2:
The patent replaces the hydraulic system with an electrical system. The actuator (electromechanical device) directly moves the park rod without requiring hydraulic fluid pressure, converting the control mechanism from hydraulic to electrical while achieving sufficient force for reliable engagement
2Reliability
If a lock ball mechanism is used to secure the servo piston, then the transmission can be locked in out-of-park mode, but the lock ball may become lodged and prevent disengagement
Solution Approach 1:
The patent removes the lock ball mechanism entirely from the system. Instead of using a lock ball to secure the servo piston, the design uses a direct mechanical linkage where the actuator moves the park rod, which directly engages or disengages the park pawl from the park gear, eliminating the intermediary lock ball that could become lodged
Solution Approach 2:
Instead of using a positive locking mechanism (lock ball) that requires release, the patent uses a spring-biased system where the park pawl is naturally biased toward the engaged position by the spring, and disengagement occurs when the actuator reverses direction, allowing the spring to automatically return the mechanism to the disengaged state
3Length of moving object
If a hydraulic system with servo piston is used, then the park rod position can be adjusted, but the hydraulic pressure may be insufficient in hybrid electric vehicles
Solution Approach 1:
The patent replaces the hydraulic pressure-dependent servo piston with an electromechanical actuator that generates mechanical force directly. The actuator moves the park rod through a slot in a support structure, providing sufficient force for position adjustment without relying on hydraulic fluid pressure, making the system suitable for hybrid electric vehicles with limited hydraulic capacity
Solution Approach 2:
The patent removes the servo piston and hydraulic circuitry from the system, eliminating the component that required hydraulic pressure for operation. The park rod position is adjusted directly by the actuator through mechanical means, bypassing the need for hydraulic pressure generation
4Ease of operation
If a hydraulic system is included in the transmission, then the park lock can be actuated, but the overall packaging size of the transmission increases
Solution Approach 1:
The patent extracts and removes the hydraulic system components (reservoir, pump, valves, hoses, servo piston) from the transmission assembly, retaining only the essential electromechanical components (actuator, park rod, park pawl, spring). This significant reduction in component count directly decreases the transmission's packaging volume while preserving park lock actuation functionality
Solution Approach 2:
The patent substitutes the bulky hydraulic system with a compact electromechanical actuator. The actuator integrates multiple functions (force generation, position control) in a single device, replacing what previously required multiple hydraulic components, thereby reducing the overall transmission packaging size
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 solution ensures reliable engagement and disengagement of the park lock without hydraulic pressure, reducing packaging size and enhancing operational reliability by using an electrical system to control the park lock mechanism.
Implementation Method 1
a solenoid electromechanically coupled to the shaft
Implementation Method 2
The shaft may be biased by a biasing member toward the pivotable pawl
Data Source
AI summary
Methods and systems are provided for a park lock system for an automatic transmission. In one example, a park lock system may include a slideable element coupled to a park rod, a lock slot formed by the slideable element, a cam coupled to an end of a shaft, the shaft positioned within a solenoid and moveable by energization of the solenoid, and a pivotable pawl adapted to couple with the lock slot. In one example, the pivotable pawl is coupled to the lock slot by energization of the solenoid, and a position of the slideable element is locked.