Method for determining the instant of reaching of the stroke end position in the deactivation phase of a movable element having shutter function forming part of a solenoid valve

• US 20050146408A1
• Filed: 11/22/2004
• Published: 07/07/2005
• Est. Priority Date: 11/21/2003
• Status: Active Grant

• Current Assignee: C.R.F. Societa Consortile Per Azioni
• Original Assignee: Cefla Societa' Cooperativa
• Inventors: Traversa, Piergiacomo, Pisoni, Alberto
• Granted Patent: US 7,058,538 B2
• Time in Patent Office: Days
• US Class Current: 335/220
• CPC Class Codes: F02D 2041/2034 Control of the current gradient
• CPC Class Codes: F02D 2041/2055 with means for determining actual opening or closing time
• CPC Class Codes: F02D 2041/2058 using information of the actual current value
• CPC Class Codes: F02D 2200/063 Lift of the valve needle
• CPC Class Codes: F02D 2250/16 End position calibration, i.e. calculation or measurement of actuator end positions, e.g. for throttle or its driving actuator
• CPC Class Codes: F02D 41/20 Output circuits, e.g. for controlling currents in command coils
• CPC Class Codes: F02D 41/2416 Interpolation techniques
• CPC Class Codes: F02D 41/2464 Characteristics of actuators

Abstract

The invention describes a method for determining the stroke end instant of the shutter during the deactivation phase of an electro-valve. The proposed method comprises the following steps: assessment of nominal deactivation time and deduction from said time of the assessed instant in which the deactivated shutter reaches the stroke end position, application of an appreciable current flow through the coil during shutter motion, after coil deactivation, adjusted in a time range comprising said assessed nominal deactivation instant, acquisition of a convenient number of current samples, identification of two adequate interpolation curves for acquired data, which approximate the development of the samples acquired before and after the instant in which the shutter reaches the stroke end, respectively, determination of the intersection point of said interpolation curves, from which the intersection instant can be inferred, identification of shutter stroke end instant with said intersection instant.

Claims

1. Method for determining the instant of reaching of the stroke end position in the deactivation phase of a movable element acting as a shutter and being part of a solenoid electro-valve, wherein it comprises the following steps:

a) assessment of nominal deactivation time and deduction from said time of the assessed instant in which the deactivated shutter reaches the stroke end position,

b) application of an appreciable current flow through the solenoid during shutter motion, after solenoid deactivation, adjusted in a time range comprising the assessed nominal deactivation instant,

c) acquisition of a convenient number of current samples,

d) identification of two interpolation curves for acquired data, which approximate the development of the samples acquired before and after the instant in which the shutter reaches the stroke end, respectively,

e) determination of the intersection point of said interpolation curves, from which the intersection instant can be inferred,

f) identification of shutter stroke end instant with said intersection instant.

2. Method according to claim 1, wherein the current on which the characteristic change occurs is supplied by a dedicated circuit.

3. Method according to claim 1, wherein the current on which the characteristic change occurs is generated by remanent magnetization in armature material.

4. Method according to claim 2, wherein the current on which the characteristic change occurs is measured through a circuit.