Parking Lock Hydraulic Cut Valve Pressure Synchronization
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Solution Overview
Problem
Existing parking lock apparatuses face malfunctions due to differences in the rising characteristics of line pressures in hydraulic circuits, leading to misactivation of the piston and failure to maintain the parking lock position as intended.
Innovation Solution
Incorporating a hydraulic cut valve in the third oil passage that opens when the oil pressure difference between the line pressures exceeds a predetermined threshold, and using chokes in the oil passages to regulate the rising characteristics, ensuring the piston is moved to the correct position quickly and accurately.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If line pressure is applied to the hydraulic circuit at startup, then the parking lock apparatus should operate, but malfunction occurs due to difference in rising characteristics of line pressures in different oil passages
Solution Approach 1:
A hydraulic cut valve is introduced as an intermediary component in the third oil passage. This valve monitors the pressure difference between the third oil passage (containing the valve) and the fourth oil passage, and only allows line pressure to reach the first end of the slider when the pressure difference exceeds a predetermined threshold. This mediates the pressure transmission to ensure synchronized operation.
Solution Approach 2:
The system changes the pressure parameter dynamically by using a hydraulic cut valve that responds to pressure difference conditions. The valve opens only when the pressure difference between oil passages exceeds a predetermined threshold, thereby controlling the timing and synchronization of pressure application to different ends of the slider based on real-time pressure conditions.
2Reliability
If the hydraulic circuit operates without pressure synchronization control, then the structure is simple, but the parking pawl fails to engage or disengage reliably
Solution Approach 1:
The hydraulic cut valve serves as a pressure-synchronization intermediary that automatically controls pressure transmission based on differential pressure conditions. It ensures that line pressure is applied to the first end of the slider only after the second end has received sufficient pressure, thereby ensuring reliable parking pawl engagement without requiring complex external control systems.
Solution Approach 2:
The hydraulic cut valve automatically regulates pressure synchronization based on inherent pressure differences in the hydraulic circuit. The valve opens when the pressure difference between oil passages exceeds a predetermined threshold, enabling the system to self-regulate and synchronize pressure application without external intervention or complex control logic.
3Manufacturing precision
If chokes are added to regulate line pressure rising characteristics, then pressure synchronization is achieved, but the device complexity increases
Solution Approach 1:
Chokes are strategically placed at specific locations within the oil passages (first, second, and fourth oil passages) to locally regulate pressure rise characteristics. Each choke is positioned to control the pressure transmission to specific ends of the slider, creating localized pressure regulation zones that achieve overall synchronization without requiring system-wide complexity.
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
Prevents malfunctions by synchronizing the line pressure rise in the hydraulic circuit, ensuring reliable engagement and disengagement of the parking pawl with the parking gear, and enabling quick response to driver inputs without waiting time.
Implementation Method 1
a hydraulic cut valve that is opened when the oil pressure in the third oil passage is higher than or equal to a predetermined oil pressure that is determined by a difference, at a start of the hydraulic circuit, between the line pressure applied through the fourth oil passage to the second end of the slider and the line pressure applied through the third oil passage to the first end of the slider
Implementation Method 2
a first choke at which the third oil passage is narrowed such that, at a start of the hydraulic circuit, a rising characteristic of the line pressure applied through the third oil passage to the first end of the slider is lower than a rising characteristic of the line pressure applied through the fourth oil passage to the second end of the slider
Data Source
AI summary
A parking lock apparatus includes a parking gear rotatable together with a rotating body of a transmission. A slider is to be switched between a parking lock position in which a parking pawl is in engagement with the parking gear and a parking release position in which the parking pawl is out of engagement with the parking gear. A hydraulic circuit includes a third oil passage through which a first line pressure is applied to push the slider toward the parking release position, a fourth oil passage through which a second line pressure is applied to push the slider toward the parking lock direction, and a hydraulic cut valve provided in the third oil passage to be opened when a difference between the first line pressure and the second line pressure is higher than or equal to a threshold pressure when applying line