Automatic Transmission Solenoid Valve Cold Climate Control
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Solution Overview
Problem
Hydraulic pressure modulation solenoid valves in automatic gearboxes become stuck in cold climates, leading to uncontrolled pressure levels and potential damage to hydraulic components, causing engine starting issues and increased fuel consumption.
Innovation Solution
A control system that determines imminent powertrain start through sensors and applies an activation command with an inrush current followed by a holding current to release energy around the solenoid valve, preventing sticking and ensuring proper pressure regulation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the vehicle operates in cold climates, then the solenoid valve becomes stuck due to increased oil viscosity, but applying continuous activation commands would increase energy consumption
Solution Approach 1:
The control system detects cold climate conditions (temperature below threshold) and applies activation commands to the solenoid valve before the vehicle actually starts operating. This preliminary action prevents the valve from getting stuck due to cold, viscous oil, ensuring reliable operation from the beginning of vehicle operation without requiring continuous energy input during normal operation.
Solution Approach 2:
Instead of continuous activation, the control system applies periodic activation commands to the solenoid valve during cold operation. The valve is activated at specific intervals or under specific conditions (such as during gear shifts or at startup), which is sufficient to prevent sticking while minimizing energy consumption compared to continuous activation.
2Reliability
If the solenoid valve is stuck in cold climates, then pressure regulation fails causing component damage, but increasing activation current would prevent sticking
Solution Approach 1:
The control system changes the activation current parameter based on temperature conditions. In cold climates, a higher activation current is applied to generate sufficient electromagnetic force to overcome the increased oil viscosity and prevent valve sticking. When temperatures are normal, the standard activation current is used, avoiding unnecessary high force application.
3Manufacturing precision
If the solenoid valve core moves freely, then pressure modulation is precise, but in cold climates the core sticks and causes uncontrolled pressure levels
Solution Approach 1:
The control system applies a preliminary counteracting force to the solenoid valve core in cold climates by activating the valve before operation. This preliminary anti-action counteracts the sticking effect of cold, viscous oil on the valve core, ensuring that the core can move freely when needed for precise pressure modulation during actual vehicle operation.
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 manages hydraulic pressure, preventing component damage and improving engine starting, fuel efficiency, and mechanical reliability across varying temperatures.
Implementation Method 1
the electromagnetic force generated by the inrush current must be significantly greater than the return force of the spring, while the electromagnetic force generated by the holding current must be substantially equal to the return force of the spring
Implementation Method 2
a return spring 11 which constrains the needle 10, a calibration cap 12 which adjusts the force of constraint of the spring 11
Implementation Method 3
the control of these ratios is ensured thanks to the pressurization of hydraulic components such as the cylinders, clutches and brakes described above
Implementation Method 4
A hydraulic clutch or brake comprising a friction system with several discs is capable of transmitting engine torque as long as the force exerted on the surface of the control piston is sufficient
Data Source
Figure 1~2
Figure 3~4
AI summary
System for controlling a motor vehicle automatic transmission, comprising at least one modulation solenoid valve positioned in a hydraulic circuit. The system comprises a means (19) for determining extreme climate conditions, able to compare a temperature measurement near the modulation solenoid valves to a threshold, a means (20) for determining the imminence of a start up of the power train of the vehicle based on at least one signal from a sensor, connected as input to a means (21) for controlling the modulation solenoid valves, able to emit a control signal modulated by a cyclic ratio, comprising an inrush current followed by a holding current, and a deactivation means (22) able to deactivate the means (21) for controlling the activation of the modulation solenoid valves when the power train is started up.