Low current solenoid valve

• US 6,412,335 B1
• Filed: 11/08/2000
• Issued: 07/02/2002
• Est. Priority Date: 11/08/2000
• Status: Expired due to Fees

• Current Assignee: Eaton Corp. (Wisconsin) (Eaton Corporation PLC.)
• Original Assignee: Eaton Corp. (Wisconsin) (Eaton Corporation PLC.)
• Inventors: Sosnowski, David R., Detweiler, Charles A., Beneker, Gerrit V., DeLand, Daniel L.
• Primary Examiner(s): Williams, Hezron
• Assistant Examiner(s): Garber, Charles D.
• Application Number:
  US09/708,941
• Time in Patent Office: 601 Days
• Field of Search: 73/405.R, 73/492, 73/497, 731/181, 123/518, 123/519, 123/520, 251/129.15, 251/129.19
• US Class Current: 73/40.50R
• CPC Class Codes: F02M 2025/0845 Electromagnetic valves
• CPC Class Codes: F02M 25/0809 Judging failure of purge control system
• 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

Abstract

A solenoid operated valve is connected in series with a resistor and a PTC thermistor. Upon coil energization, the armature moves to close the valve member against a valve seat and further armature movement to close an air gap with a pole piece is absorbed by a spring between the armature and valve member. Upon closure of the air gap, the magnetic reluctance between the armature and pole piece is decreased such that significantly less current is required in the coil to hold the valve closed. Upon heating of the thermistor, the resistance is increased sufficiently to reduce the current to the hold-close level and less power is required thereafter to maintain the valve closed. The valve is applied to on-board vehicle diagnostic procedures performed after engine shut-down where current must be minimized to prevent battery drain to a level preventing re-start.

Claims

1. A diagnostic system for a motor vehicle fuel vapor management system comprising:

(a) a fuel vapor storage canister connected to receive fuel vapor through a conduit from the vehicle fuel tank and atmospheric air;

(b) means for controlling flow of vapor from said canister to the air inlet of the vehicle motor;

(c) an electrically operated valve disposed for controlling venting of atmospheric air to said canister; and

,

(d) a PTC resistor electrically in circuit with said electrically operated valve, said resistor operative to reduce the current flow in said valve after a predetermined time interval, wherein said valve has a solenoid operator with an armature connected to a valve element moveable between an open and closed position wherein said armature continues movement with respect to said valve element for closing a working air gap with a pole piece when said valve element is in the closed position.

2. A diagnostic system for a motor vehicle fuel vapor management system comprising:

(a) a fuel vapor storage canister connected to receive fuel vapor through a conduit from the vehicle fuel tank and atmospheric air;

(b) means for controlling flow of vapor from said canister to the air inlet of the vehicle motor;

(c) an electrically operated valve disposed for controlling venting of atmospheric air to said canister; and

,

(d) a PTC resistor electrically in circuit with said electrically operated valve, said resistor operative to reduce the current flow in said valve after a predetermined time interval, wherein said electrically operated valve includes a solenoid having a moveable armature defining a working air gap with a stationary pole piece; and

, said valve includes means operable to permit movement of said armature after valve closure to permit closing of said working air gap for maximizing flux concentration and thereby holding said valve closed with reduced current.

3. A method of diagnosing leakage in a motor vehicle fuel vapor management system of the type having a storage canister receiving vapor from the fuel tank and means for purging the canister through an atmospheric air inlet in the canister to the engine inlet upon engine start up comprising:

(a) disposing an electrically operated valve in the canister atmospheric air inlet and energizing and closing said valve upon engine shut down;

(b) maintaining said valve energized and detecting the pressure in said canister after a specified time interval following engine shut down;

(c) disposing a PTC resistor in circuit with said valve and decreasing the current flow in said valve to a pre-selected threshold during said maintaining and said step of energizing and closing said valve includes energizing a coil and moving an armature for closing said valve, wherein said step of moving an armature includes continuing armature movement after closing said valve and closing a working air gap for maximizing flux and operating said coil at substantially reduced current.