US 6,332,454 B1 · Electromagnetic valve driving apparatus having current limit switching function

Abstract

A driving apparatus for an electromagnetic valve which supplies fuel to an engine comprises a conduction control circuit and a current-limit-value setting circuit. The conduction control circuit turns on and off an FET so that a conduction current flowing through a coil of the electromagnetic valve has a magnitude equal to a predetermined current limit value while a microcomputer is outputting a driving signal to the conduction control circuit. The predetermined current limit value used in the conduction control circuit is set at a first current limit value during a predetermined period starting at a point of time the microcomputer outputs the driving signal. When the predetermined period has lapsed, the predetermined current limit value is switched from the first current limit value to a second current limit value which is smaller than the first current limit value. In addition, when the microcomputer detects a start state of the engine or a low level state of a battery voltage, the second current limit value is raised to the first current limit value to thereby improve the starting characteristics of the engine.

Claims21

Dependent claims

A driving apparatus for an electromagnetic valve having a coil for supplying fuel to an engine of a vehicle comprising:

a switching device provided in series with the coil for supplying a conduction current from a battery to the coil to drive the electromagnetic valve when turned on;
driving signal outputting means for outputting a driving signal for turning on the switching device in response to the rotation of the engine;
conduction control means for turning on the switching device so as to set the conduction current at a predetermined current limit value while the driving signal outputting means is outputting the driving signal;
and
current-limit-value setting means for setting the predetermined current limit value of the conduction control means at a first current limit value starting at a point of time the driving signal is output by the driving signal outputting means till a predetermined condition is satisfied, and setting the predetermined current limit value of the conduction control means at a second current limit value smaller than the first current limit value after the predetermined condition gets satisfied until the driving signal is no longer output,
wherein current-limit-value changing means is provided to change the second current limit value set by the current-limit-value setting means to a third current limit value larger than the second current limit value, when the engine is in the state of being started.

3 more elements

A driving apparatus for an electromagnetic valve having a coil for supplying fuel to an engine of a vehicle comprising:

a switching device provided in series with the coil for supplying a conduction current from a battery to the coil to drive the electromagnetic valve when turned on;
driving signal outputting means for outputting a driving signal for turning on the switching device in response to the rotation of the engine;
conduction control means for turning on the switching device so as to set the conduction current at a predetermined current limit value while the driving signal outputting means is outputting the driving signal;
and
current-limit-value setting means for setting the predetermined current limit value of the conduction control means at a first current limit value starting at a point of time the driving signal is output by the driving signal outputting means till a predetermined condition is satisfied, and setting the predetermined current limit value of the conduction control means at a second current limit value smaller than the first current limit value after the predetermined condition gets satisfied until the driving signal is no longer output,
wherein current-limit-value changing means is provided to change the second current limit value set by the current-limit-value setting means to a third current limit value larger than the second current limit value, when a voltage of the battery is decreased to be lower than a predetermined voltage.

3 more elements

A driving apparatus for an electromagnetic valve having a coil for supplying fuel to an engine of a vehicle comprising:

a switching device provided in series with the coil for supplying a conduction current from a battery to the coil to drive the electromagnetic valve when turned on;
driving signal outputting means for outputting a driving signal for turning on the switching device in response to the rotation of the engine;
conduction control means for turning on the switching device so as to set the conduction current at a predetermined current limit value while the driving signal outputting means is outputting the driving signal;
and
current-limit-value setting means for setting the predetermined current limit value of the conduction control means at a first current limit value starting at a point of time the driving signal is output by the driving signal outputting means till a predetermined condition is satisfied, and setting the predetermined current limit value of the conduction control means at a second current limit value smaller than the first current limit value after the predetermined condition gets satisfied until the driving signal is no longer output,
wherein current-limit-value changing means is provided to change the second current limit value set by the current-limit-value setting means to a third current limit value larger than the second current limit value, when a parameter indicative of at least one of the engine is in the state of being started and a voltage of the battery is lower than a predetermined voltage is detected.

3 more elements

Dependencies are inferred from the claim text.

Electromagnetic valve driving apparatus having current limit switching function

Life of this patent

Electromagnetic valve driving apparatus having current limit switching function

Life of this patent

Abstract

Claims21