# US 5,699,775 A · Failure diagnosis device of fuel evaporation preventive apparatus > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 5,699,775 A - Document ID: US5699775A - Status: Granted - Kind: A - Application number: 08/708,480 - Filed: 1996-08-13 - Granted: 1997-12-23 - Earliest claimed: 1996-03-04 - Assignees: Mitsubishi Denki Kabushiki Kaisha - Inventors: Tadahiro Azuma - Web page: https://patentgrep.com/patent/US5699775A ## CPC - F02M 25/0809: {Judging failure of purge control system} - B60K 15/035: characterised by venting means - B60K 2015/03217: {Fuel level sensors} - F02D 33/003: {Controlling the feeding of liquid fuel from storage containers to carburettors or fuel-injection apparatus (control of electrical fuel pumps F02D41/3082, controlling fuel flow to a common rail F02D41/3845); Failure or leakage prevention; Diagnosis or detection of failure; Arrangement of sensors in the fuel system; Electric wiring; Electrostatic discharge} - F02M 37/0082: {Devices inside the fuel tank other than fuel pumps or filters (electrical pumps submerged in fuel tanks F02M37/10, jet pumps F02M37/025)} - F02M: SUPPLYING COMBUSTION ENGINES IN GENERAL WITH COMBUSTIBLE MIXTURES OR CONSTITUENTS THEREOF - B60K: ARRANGEMENT OR MOUNTING OF PROPULSION UNITS OR OF TRANSMISSIONS IN VEHICLES; ARRANGEMENT OR MOUNTING OF PLURAL DIVERSE PRIME-MOVERS IN VEHICLES; AUXILIARY DRIVES FOR VEHICLES; INSTRUMENTATION OR DASHBOARDS FOR VEHICLES; ARRANGEMENTS IN CONNECTION WITH COOLING, AIR INTAKE, GAS EXHAUST OR FUEL SUPPLY OF PROPULSION UNITS IN VEHICLES - F02D: CONTROLLING COMBUSTION ENGINES (vehicle fittings, acting on a single sub-unit only, for automatically controlling vehicle speed B60K31/00; conjoint control of vehicle sub-units of different type or different function, road vehicle drive control systems for purposes other than the control of a single sub-unit B60W) ## Abstract A failure diagnosis device of a fuel evaporation preventive apparatus including: a fuel evaporation preventive apparatus having a canister having an atmospheric hole communicating with outside air and installed in the middle of a purge passage communicating a fuel tank with an intake pipe, for preventing evaporation of fuel by adsorbing at any time fuel gas generated in the fuel tank by an adsorber incorporated in the canister and pertinently introducing the adsorbed fuel gas into the intake pipe by controlling a purge control valve in accordance with a running state of an internal combustion engine; an initializing apparatus for controlling an inner pressure of the fuel tank to a predetermined initial pressure; a pressure controlling apparatus for changing the initial pressure to a predetermined target pressure and controlling a purge amount at that time to a constant flow rate by closing the atmospheric hole and driving the purge control valve; a hermetically enclosing apparatus for constituting a hermetically enclosed section in the fuel evaporation preventive apparatus by closing both the purge control valve and the atmospheric hole when the inner pressure of the fuel tank reaches the target pressure; a pressure detecting apparatus installed in the hermetically enclosed section; and a failure diagnosing apparatus for diagnosing failure of the fuel evaporation preventive apparatus based on a change of an inner pressure of the hermetically enclosed section. ## Claims ### Claim 1 A failure diagnosis device of the fuel evaporation preventive apparatus, comprising: a fuel evaporation prevention apparatus having a canister having an atmospheric hole communicating with outside air and installed in a purge passage connecting a fuel tank with an intake pipe, for preventing evaporation of fuel by adsorbing fuel gas generated in the fuel tank by an adsorber incorporated in the canister and pertinently introducing the adsorbed fuel gas into the intake pipe by controlling a purge control valve in accordance with a running state of an internal combustion engine; initializing means for controlling an inner pressure of the fuel tank to a predetermined initial pressure; pressure controlling means for changing the initial pressure to a predetermined target pressure and controlling a purge amount at that time to a constant flow rate by closing the atmospheric hole and driving the purge control valve; hermetically enclosing means for forming a hermetically enclosed section in the fuel evaporation preventive apparatus by closing both the purge control valve and the atmospheric hole when the inner pressure of the fuel tank reaches the target pressure; pressure detecting means installed in the hermetically enclosed section for detecting a minimum pressure occurring in the hermetically enclosed section after the purge control valve and the atmospheric hole are closed; and failure diagnosing means for diagnosing failure of the fuel evaporation preventive apparatus by comparing the minimum pressure in the hermetically enclosed section with a predetermined reference value. ### Claim 2 (depends on 1) The failure diagnosis device of the fuel evaporation preventive apparatus according to claim 1, further comprising an intake pipe pressure detecting means for detecting an inner pressure of the intake pipe and wherein the pressure controlling means calculates a control amount of the purge control valve based on the inner pressure of the intake pipe. ### Claim 3 (depends on 1) The failure diagnosis device of the fuel evaporation preventive apparatus according to claim 1, wherein the failure diagnosing means diagnoses that the fuel evaporation preventive apparatus is normal when the inner pressure of the hermetically enclosed section is equal to or less than a predetermined protective pressure and opens the atmospheric hole. ### Claim 4 (depends on 1) The failure diagnosis device of the fuel evaporation preventive apparatus according to claim 1, wherein the constant flow rate is set such that the inner pressure in the hermetically enclosed section overshoots the target pressure during a period of pressure overshoot occurring after the purge control valve and atmospheric hole are closed, and wherein the minimum pressure is detected during the period of pressure overshoot. ### Claim 5 (depends on 4) The failure diagnosis device of the fuel evaporation preventive apparatus according to claim 4, wherein the failure diagnosing means diagnoses that the fuel evaporation preventive apparatus is normal when the inner pressure of the hermetically enclosed section is equal to or less than a predetermined protective pressure, the failure diagnosing means comparing the inner pressure of the hermetically enclosed section to the predetermined protective pressure during the period of pressure overshoot. ### Claim 6 (depends on 2) The failure diagnosis device of the fuel evaporation preventive apparatus according to claim 2, wherein the constant flow rate is maintained by adjusting the control amount of the purge control valve as a function of the inner pressure of the intake pipe. ### Claim 7 A failure diagnosis device of the fuel evaporation preventive apparatus, comprising: a fuel evaporation prevention apparatus having a canister having an atmospheric hole communicating with outside air and installed in a purge passage connecting a fuel tank with an intake pipe, for preventing evaporation of fuel by adsorbing fuel gas generated in the fuel tank by an adsorber incorporated in the canister and pertinently introducing the adsorbed fuel gas into the intake pipe by controlling a purge control valve in accordance with a running state of an internal combustion engine; initializing means for controlling an inner pressure of the fuel tank to a predetermined initial pressure; pressure controlling means for changing the initial pressure to a predetermined target pressure and controlling a purge amount at that time to a constant flow rate by closing the atmospheric hole and driving the purge control valve; hermetically enclosing means for forming a hermetically enclosed section in the fuel evaporation preventive apparatus by closing both the purge control valve and the atmospheric hole when the inner pressure of the fuel tank reaches the target pressure, wherein the constant flow rate is set such that the inner pressure in the hermetically enclosed section overshoots the target pressure during a period of pressure overshoot occurring after the purge control valve and atmospheric hole are closed; pressure detecting means installed in the hermetically enclosed section for detecting the inner pressure of the hermetically enclosed section; and failure diagnosing means for diagnosing failure of the fuel evaporation preventive apparatus, wherein the failure diagnosing means diagnoses failure by comparing the inner pressure of the hermetically enclosed section with a predetermined reference value at a point in time during the period of pressure overshoot. ### Claim 8 (depends on 7) The failure diagnosis device of the fuel evaporation preventive apparatus according to claim 7, further comprising an intake pipe pressure detecting means for detecting an inner pressure of the intake pipe and wherein the pressure controlling means calculates a control amount of the purge control valve based on the inner pressure of the intake pipe. ### Claim 9 (depends on 8) The failure diagnosis device of the fuel evaporation preventive apparatus according to claim 8, wherein the constant flow rate is maintained by adjusting the control amount of the purge control valve as a function of the inner pressure of the intake pipe. ### Claim 10 (depends on 7) The failure diagnosis device of the fuel evaporation preventive apparatus according to claim 7, wherein the failure diagnosing means diagnoses that the fuel evaporation preventive apparatus is normal when the inner pressure of the hermetically enclosed section is equal to or less than a predetermined protective pressure and opens the atmospheric hole. ### Claim 11 (depends on 10) The failure diagnosis device of the fuel evaporation preventive apparatus according to claim 10, wherein the failure diagnosing means compares the inner pressure of the hermetically enclosed section to the predetermined protective pressure during the period of pressure overshoot.