Vacuum Generator Spool Valve for Evaporative Emissions Leak Testing
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Solution Overview
Problem
Conventional hand-operated vacuum pumps are inadequate for timely and safe vacuum-decay testing of motor vehicle evaporative emissions systems due to excessive vacuum draw, hazardous flammable vapors, and potential for explosive conditions, as well as the risk of system damage from improper vacuum levels.
Innovation Solution
A compact, handheld vacuum generator using a spool valve mechanism with a pressure regulator and inert gas inlet to control vacuum strength, featuring a spool valve with proximal and distal spools and intermediate spools to manage gas flow and create a controlled vacuum, while diluting hydrocarbon vapors to prevent explosions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a hand operated vacuum pump is used to evacuate the evaporative emissions system, then the system can be tested for leaks, but a time delay of 5 to 10 minutes is required to evacuate the system
Solution Approach 1:
The patent replaces the manual mechanical vacuum pump with an automated solenoid valve system controlled by a microprocessor. The solenoid valve automatically controls gas flow to create and maintain vacuum, eliminating the manual pumping action and reducing evacuation time from 5-10 minutes to a much shorter automated cycle.
Solution Approach 2:
The system performs self-regulation through the microprocessor-controlled solenoid valve that automatically maintains the desired vacuum level without continuous manual intervention. The system monitors vacuum levels and adjusts gas flow automatically, enabling the evacuation process to serve itself rather than requiring continuous operator input.
2Ease of operation
If a hand operated vacuum pump is used, then vacuum can be created, but the vapors that evacuate from the pump are flammable and could lead to a potentially hazardous explosive condition
Solution Approach 1:
The patent introduces an inert gas (such as nitrogen or carbon dioxide) through the solenoid valve system to displace and dilute flammable hydrocarbon vapors in the evaporative emissions system. This creates an inert atmosphere that prevents explosive conditions while still allowing vacuum creation and leak testing to proceed safely.
Solution Approach 2:
The solenoid valve system acts as an intermediary between the vacuum source and the evaporative emissions system, controlling the introduction of inert gas to safely manage vapor evacuation. The microprocessor-controlled valve regulates gas flow to prevent direct contact between flammable vapors and ignition sources while maintaining testing capability.
3Reliability
If a hand operated vacuum pump is used, then vacuum testing can be performed, but after the pump is disconnected from the test port, ambient air flows back into the system, thereby creating a potentially explosive mixture
Solution Approach 1:
The system performs preliminary action by continuously maintaining a controlled atmosphere with inert gas before, during, and after the vacuum testing process. The solenoid valve system ensures that inert gas is present in the system beforehand and continues to be introduced after disconnection, preventing ambient air from entering and forming explosive mixtures.
Solution Approach 2:
The microprocessor system provides feedback control by monitoring vacuum levels and solenoid valve position, automatically adjusting inert gas flow to maintain safe atmospheric conditions. This closed-loop control ensures that the system responds to changing conditions and maintains protection against explosive mixture formation throughout the entire testing cycle.
4Adaptability or versatility
If a hand operated vacuum pump is used, then the technician can perform vacuum testing, but the vacuum level is selected by the technician which may pull too much vacuum and damage the vehicle or not enough vacuum rendering the test inaccurate
Solution Approach 1:
The patent implements feedback control through the microprocessor that continuously monitors vacuum levels in the evaporative emissions system. Based on this feedback, the system automatically adjusts solenoid valve operation to maintain the optimal vacuum level for accurate leak testing, preventing both excessive vacuum that could damage the vehicle and insufficient vacuum that would render the test inaccurate.
Solution Approach 2:
The system performs self-regulation of vacuum levels without requiring technician judgment or manual adjustment. The microprocessor-controlled solenoid valve automatically maintains the precise vacuum level needed for accurate testing, eliminating human error in vacuum level selection and ensuring consistent, reliable results.
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
Enables reliable, timely, and safe vacuum-decay testing of motor vehicle evaporative emissions systems by controlling vacuum levels, preventing system damage, and mitigating hazardous vapor risks, ensuring accurate and repeatable results.
Implementation Method 1
The venturi is axially aligned with an exhaust port to the atmosphere
Implementation Method 2
A coil spring is located between the spool valve and the stationary venturi so as to automatically bias the spool valve towards an initial at-rest stage within the spool valve bore
Data Source
AI summary
A compact (e.g., hand held) vacuum generator having particular application for creating a vacuum within the evaporative emissions system (e.g., a gas tank) of a motor vehicle so that a vacuum-decay test can be performed to test the system for leaks while mitigating the hazardous effects of potentially explosive hydrocarbon vapors. The vacuum generator includes a spool valve that has an internal passage and is capable of sliding through a spool valve bore in response to a pushing force. During an at-rest stage of the spool valve within the spool valve bore, the system to be tested is disconnected from the vacuum generator. During a transition stage of the spool valve within the spool valve bore, inlet gas under pressure is blown through the internal passage of the spool valve to the atmosphere by way of a vacuum generating venturi, whereby a vacuum begins to form in a vacuum passage. During a vacuum stage of the spool valve within the spool valve bore, the vacuum passage is connected between the vacuum generating venturi and the system under test at a dual vacuum inlet port so that the system will be evacuated to the atmosphere as inlet gas under pressure is blown to the atmosphere through the internal passage of the spool valve and the vacuum generating venturi. A vacuum gauge coupled to the dual vacuum inlet port is responsive to the decay of the vacuum created within the system under test to provide an indication of a leak.