System for supplying liquefied gas to a combustion engine with a minimum liquefied-gas level detector

• US 20050166972A1
• Filed: 01/18/2005
• Published: 08/04/2005
• Est. Priority Date: 02/02/2004
• Status: Active Grant

• Current Assignee: Luxembourg Patent Company S.A. (Rotarex SA)
• Original Assignee: Luxembourg Patent Company S.A. (Rotarex SA)
• Inventors: Casier, Michael
• Granted Patent: US 7,401,625 B2
• Time in Patent Office: Days
• US Class Current: 137/558
• CPC Class Codes: F02D 19/027 Determining the fuel pressure, temperature or volume flow, the fuel tank fill level or a valve position
• CPC Class Codes: F02D 19/029 Determining density, viscosity, concentration or composition
• CPC Class Codes: F02M 21/0212 comprising at least 3 C-Atoms, e.g. liquefied petroleum gas [LPG], propane or butane
• CPC Class Codes: F02M 21/0221 Fuel storage reservoirs, e.g. cryogenic tanks
• CPC Class Codes: F02M 21/0242 Shut-off valves; Check valves; Safety valves; Pressure relief valves
• CPC Class Codes: F02M 21/0287 characterised by the transition from liquid to gaseous phase F02M21/06 takes precedence; Injection in liquid phase; Cooling and low temperature storage
• CPC Class Codes: F17C 13/025 having the pressure as the parameter
• CPC Class Codes: F17C 13/026 having the temperature as the parameter
• CPC Class Codes: F17C 2221/035 Propane butane, e.g. LPG, GPL
• CPC Class Codes: F17C 2223/0153 Liquefied gas, e.g. LPG, GPL
• CPC Class Codes: F17C 2223/033 Small pressure, e.g. for liquefied gas
• CPC Class Codes: F17C 2223/035 High pressure (>10 bar)
• CPC Class Codes: F17C 2223/043 in the gas
• CPC Class Codes: F17C 2223/047 with a dip tube
• CPC Class Codes: F17C 2227/0107 by pressurising the ullage
• CPC Class Codes: F17C 2250/032 using computers
• CPC Class Codes: F17C 2250/036 using alarms
• CPC Class Codes: F17C 2250/0408 Level of content in the vessel
• CPC Class Codes: F17C 2250/043 Pressure
• CPC Class Codes: F17C 2250/077 when empty
• CPC Class Codes: F17C 2265/031 : by discharge
• CPC Class Codes: F17C 2265/066 : for feeding engines for propulsion
• CPC Class Codes: F17C 2270/0168 : by vehicles
• CPC Class Codes: F17C 7/02 : Discharging liquefied gases
• CPC Class Codes: F17C 7/04 : with change of state, e.g. vaporisation
• CPC Class Codes: G01F 23/247 : for discrete levels
• CPC Class Codes: Y02T 10/30 : Use of alternative fuels, e.g. biofuels
• CPC Class Codes: Y10T 137/8342 : Liquid level responsive indicator, recorder or alarm

Abstract

To detect the volume of gas remaining in a gas bottle or a fixed tank of a system for supplying liquefied gas as fuel for a combustion engine, a positive temperature coefficient (or PTC) probe (16) is placed in the gas feed line (12) between the gas source and the combustion engine. The PTC probe (16) detects the change of phase, from the liquid phase of the liquefied gas to the gaseous phase, in the feed line (12) and delivers an electrical signal to an electronic circuit that triggers a visual or audible signal in response to the detection of the phase change.

Claims

1. A system for supplying liquefied gas as fuel to a combustion engine, comprising a liquefied gas source, a line for supplying gas to the engine, a minimum liquefied-gas level detector and a means for indicating detection of the minimum level wherein the minimum liquefied-gas level detector comprises a means arranged in said supply line for detecting the occurrence of the change from the liquid phase of the liquefied gas to the gaseous phase in said supply line.

2. The system of claim 1 wherein the minimum liquefied-gas level detector includes a positive temperature coefficient (PTC) probe placed in the supply line and connected into an electrical circuit that sends an electrical current via the probe for the purpose of detecting a variation in its electrical resistance resulting from an increase in its temperature after the change in the liquefied gas from the liquid phase to the gaseous phase in the supply line.

3. The system of claim 2 wherein the electronic circuit is provided with means for producing a visual or audible signal in response to detection of the variation in the electrical resistance of the probe.

4. The system of claim 2, characterized in that the supply line includes a dip tube extending in the liquid gas source up to a height corresponding to the said minimum level, and the PTC probe is placed in the supply line outside the liquefied gas source.

5. The system of claim 1 wherein the liquefied gas source is a liquefied gas bottle which is to be replaced with a new gas bottle after the change in phase of the liquefied gas in the supply line has been detected.

6. The system of claim 1 wherein the liquefied gas source is a fixed tank, the system further including means for detecting the gas pressure in the tank and a means for producing a visual or audible signal when the pressure in the tank has dropped to a value allowing the tank to be filled.