Fuel supply system for an internal combustion engine

• US 9,702,321 B2
• Filed: 07/09/2015
• Issued: 07/11/2017
• Est. Priority Date: 07/10/2014
• Status: Active Grant

• Current Assignee: Aisan Kogyo Kabushiki Kaisha, Toyota Jidosha Kabushiki Kaisha (Toyota Motor Corporation)
• Original Assignee: Aisan Kogyo Kabushiki Kaisha, Toyota Jidosha Kabushiki Kaisha (Toyota Motor Corporation)
• Inventors: Miyazaki, Ryuji, Morihiro, Kinji, Tsutsumi, Hidetoshi, Nakatsuka, Tomonori, Honda, Koji
• Primary Examiner(s): Cronin, Stephen K
• Assistant Examiner(s): Mo, Xiao
• Application Number:
  US14/795,018
• Publication Number:
  US 20160010571A1
• Time in Patent Office: 733 Days
• CPC Class Codes: F02D 2041/1431 the system including an input-output delay
• CPC Class Codes: F02D 2200/0406 Intake manifold pressure
• CPC Class Codes: F02D 41/0032 Controlling the purging of the canister as a function of the engine operating conditions
• CPC Class Codes: F02D 41/0042 Controlling the combustible mixture as a function of the canister purging, e.g. control of injected fuel to compensate for deviation of air fuel ratio when purging
• CPC Class Codes: F02M 25/0836 Arrangement of valves controlling the admission of fuel vapour to an engine, e.g. valve being disposed between fuel tank or absorption canister and intake manifold
• CPC Class Codes: F02M 25/089 Layout of the fuel vapour installation

Abstract

A fuel supply system adapted to supply fuel to an internal combustion engine has both a check valve and a purge valve disposed in a purge passage that extends from a canister to connect with an intake passage of the internal combustion engine. A controller estimates a pressure within an intermediate purge passage of the purge passage located between the check valve and the purge valve without relying on the use of a separate pressure detection device to provide information regarding the same.

Claims

1. A fuel vapor supply system configured to supply fuel vapor to an internal combustion engine having an intake passage, the fuel vapor supply system comprising:

a canister configured to store the fuel vapor;

a purge passage extending from the canister to connect to the intake passage of the internal combustion engine wherein the purge passage allows the fuel vapor stored in the canister to flow to the internal combustion engine through the purge passage;

a purge valve disposed in the purge passage wherein the purge valve is configured to regulate a flow rate of the fuel vapor flowing from the canister to the intake passage is controlled;

a check valve disposed in the purge passage between the purge valve and the intake passage wherein the check valve is configured to permit the flow of the fuel vapor from the canister to the intake passage and further wherein the check valve is configured to prevent the flow of air from the intake passage to the canister;

wherein the purge passage has an intermediate purge passage that extends from the purge valve to the check valve; and

wherein the check valve is configured to open when an intermediate purge passage pressure within the intermediate purge passage exceeds an intake passage pressure within the intake passage and the check valve is configured to close when the intermediate purge passage pressure does not exceed the intake passage pressure;

a pressure detection device configured to detect the intake passage pressure;

a controller coupled with the purge valve, wherein the controller is programmed to

control a degree of opening of the purge valve or a duty ratio wherein the duty ratio is defined as a ratio of a valve opening time to a predetermined frequency period and further wherein control of the degree of opening of the purge valve or control of the duty ratio regulates the flow rate of the fuel vapor flowing across the purge valve;

perform a purge control to control the purge valve to open with a predetermined opening degree or a predetermined duty ratio such that the fuel vapor stored in the canister flows from the canister to the internal combustion engine via the purge passage and the intake passage because of a negative pressure in the intake passage wherein the negative pressure is defined as a pressure less than an atmospheric pressure, while the fuel vapor flows across the purge valve, through the intermediate purge passage, and across the check valve in the purge passage; and

estimate the intermediate purge passage pressure within the intermediate purge passage at least partially based on the intake passage pressure detected by the pressure detection device.

2. The fuel vapor supply system according to claim 1, wherein the controller is configured to estimate the intermediate purge passage pressure to be equal to a smallest value of detected values of the intake passage pressure should the purge valve be fully closed.

3. The fuel vapor supply system according to claim 1, wherein the controller is configured to estimate the intermediate purge passage pressure to be equal to the intake passage pressure detected at a time when a predetermined pressure variation transition time has elapsed after initiating the purge control should the purge valve not be fully closed.

4. The fuel vapor supply system according to claim 3, wherein the controller is further configured to adjust a duration of the predetermined pressure variation transition time based on a difference between the intake passage pressure detected by the pressure detection device and the intermediate purge passage pressure estimated when the purge valve is fully closed.

5. The fuel vapor supply system according to claim 3, wherein the controller is configured to estimate the intermediate purge passage pressure to be equal to the atmospheric pressure provided that the intake passage pressure exceeds the atmospheric pressure at a time when the predetermined pressure variation transition time has elapsed after starting the purge control should the purge valve not be fully closed.

6. The fuel vapor supply system according to claim 1,

wherein the controller is further coupled with a fuel injector associated with the internal combustion engine and is further configured to perform a reduction control to reduce a quantity of fuel injected from the injector;

wherein the reduction control regulates the fuel injector to reduce a quantity of fuel injected from the injector to compensate for the fuel vapor supplied to the internal combustion engine during the purge control; and

wherein the reduction control begins at a time determined at least partially based on the intake passage pressure detected by the pressure detection device, the estimated pressure within the intermediate purge passage, and a predetermined arrival delay time that is a time of delay for arrival of the fuel vapor from the canister to the internal combustion engine.

7. The fuel vapor supply system according to claim 6, wherein the predetermined arrival delay time is determined based on at least one of a rotational speed of a crankshaft of the engine, a flow rate of intake air flowing through the intake passage, a degree of opening of the purge valve, and the intake passage pressure detected by the pressure detection device.

8. A system comprising:

an internal combustion engine;

an intake passage in fluid communication with the internal combustion engine wherein the intake passage is configured to supply intake air to the internal combustions engine;

a fuel tank configured to store the fuel;

a canister in fluid communication with the fuel tank wherein the canister is configured to store fuel from the fuel tank;

a purge passage extending from the canister to connect with the intake passage;

a purge valve disposed in the purge passage such that the fuel stored in the canister flows to the intake passage through the purge passage when the purge valve is open;

a check valve disposed in the purge passage at a downstream position relative to a flow of fuel from the canister to the intake passage wherein the check valve is configured to prevent flow of intake air from the intake passage to the canister through the purge passage;

a controller coupled with the purge valve wherein the controller is programmed to regulate the purge valve at least partially based on an intake passage pressure within the intake passage and an intermediate purge passage pressure within an intermediate purge passage of the purge passage located between the purge valve and the check valve; and

wherein the controller is further programmed to estimate the intermediate purge passage pressure to be equal to the intake passage pressure or an atmospheric pressure dependent on a controlled opening and closing state of the purge valve.