LPG Composition Estimation via Injector Pressure and Temperature
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Solution Overview
Problem
Existing LPG supply systems for engines with positive ignition face challenges in accurately determining LPG composition, leading to inefficient fuel switching, increased CO2 emissions, and reliability issues due to complex sensor connections and unreliable estimation methods.
Innovation Solution
A method that recognizes incipient condensation conditions in the LPG supply system by detecting specific pressure and temperature values at the injectors, using a series of parameters and observation windows to estimate the propane and/or butane percentage, and adjusts the air/fuel ratio and switching parameters accordingly, optimizing the system's operation and preventing condensation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If pressure sensor and temperature sensor are installed in the tank or high pressure line to estimate LPG composition, then composition estimation is possible, but circuit complexity increases and reliability decreases due to complex connections and potential loss points
Solution Approach 1:
The patent extracts the composition estimation function from the high-pressure circuit (tank/line) and relocates it to the low-pressure circuit at the injector. By using the existing pressure sensor and temperature sensor at the injector to detect low-pressure LPG parameters, the system eliminates the need for additional sensors in the high-pressure circuit, thereby reducing circuit complexity and improving reliability while maintaining composition estimation capability
Solution Approach 2:
The patent uses the low-pressure LPG as an intermediary to infer the composition of high-pressure LPG. By detecting pressure and temperature of vaporized LPG at the injector (low-pressure side), the system calculates composition parameters without directly measuring the high-pressure LPG, thus avoiding the reliability issues associated with high-pressure sensor installations
2Reliability
If conservative switching method is used to ensure superheated vapour, then condensation is prevented, but petrol consumption increases and CO2 emissions increase due to delayed LPG switching
Solution Approach 1:
The patent implements a feedback mechanism where the ECU continuously monitors low-pressure LPG pressure and temperature at the injector, estimates composition in real-time, and dynamically adjusts the switching decision. This closed-loop control allows the system to switch to LPG at the optimal moment based on actual composition data, preventing both condensation and unnecessary petrol consumption
Solution Approach 2:
The patent performs preliminary composition estimation by detecting low-pressure LPG parameters before the actual switching decision is made. This advance knowledge of LPG composition allows the system to prepare for switching at the optimal time, ensuring superheated vapour conditions will be met while minimizing petrol usage during the transition period
3Loss of energy
If early switching to LPG is implemented, then petrol consumption is reduced, but driveability problems occur and reliability decreases due to liquid LPG presence in the mixture
Solution Approach 1:
The real-time composition estimation feedback from low-pressure LPG measurements allows the ECU to determine the precise moment when vaporization is complete and superheated conditions are achieved. This ensures switching occurs only when safe, preventing liquid LPG injection while minimizing petrol consumption by avoiding unnecessarily delayed switching
Solution Approach 2:
The patent uses composition parameters derived from low-pressure LPG pressure and temperature measurements to dynamically adjust switching criteria. By monitoring how composition parameters evolve during the warm-up period, the system can identify the optimal switching point that ensures complete vaporization while minimizing petrol usage
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 approach allows for precise timing of fuel switching, reducing CO2 emissions, enhancing safety, driveability, and component reliability by accurately estimating LPG composition and optimizing the air/fuel ratio, thereby minimizing back switches to petrol and maximizing LPG use.
Implementation Method 1
The vaporiser/pressure reducer 3 is configured to vaporise the LPG, thus reducing the pressure to the operating pressure
Implementation Method 2
recognising an incipient condensation condition of the LPG, characterised in that the LPG in vapour form starts to pass into liquid form
Data Source
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AI summary
A method (100) for estimating the composition of LPG in an LPG supply system (1) for engines with positive ignition, the LPG supply system (1) comprising an LPG tank (2), a pressure reducer (3), a first conduit (HP) that extends between the tank (2) and the pressure reducer (3), a plurality of injectors (4) and a second conduit (LP) that extends between the pressure reducer (3) and the injectors (4), the method (100) comprising the steps of: - recognising an incipient condensation condition of the LPG (101), which takes place when the LPG in vapour form starts to pass into liquid form; - in response to the recognition of the incipient condensation condition of the LPG, detecting first LPG injection pressure and temperature values (102); - starting from the first LPG injection pressure and temperature values detected, obtaining a corresponding percentage of propane and/or butane contained in the LPG (103).