Fuel injection valve

Patent metadata

Field	Value
Publication number	US-9651008-B2
Application number	US-201314140895-A
Country	US
Kind code	B2
Filing date	Dec 26, 2013
Priority date	Dec 26, 2012
Publication date	May 16, 2017
Grant date	May 16, 2017

Abstract

A sub out-orifice and an in-orifice are respectively formed in a low pressure passage and a high pressure passage of a fixed plate. A control valve is provided at an outlet port of the low pressure passage. In a normal control, the control valve starts its control-valve opening operation when a movable plate is in contact with the fixed plate. In an interval-shortening control, the control valve starts the control-valve opening operation at an earlier timing than that in the normal control, namely during a course in which a valve body is still in its valve-body closing operation.

First claim

What is claimed is:

1. A fuel injection valve for a fuel injection system of an internal combustion engine comprising:
a valve body movably accommodated in a nozzle body and configured to open and close an injection port;
a pressure control chamber configured to apply control-chamber pressure to the valve body in a valve-body closing direction;
a fixed plate having a high pressure passage configured to supply high pressure fuel to the pressure control chamber so as to move the valve body in the valve-body closing direction, the fixed plate having a low pressure passage configured to discharge fuel out of the pressure control chamber so as to move the valve body in a valve-body opening direction;
a sub out-orifice formed in the low pressure passage configured to restrict flow rate of the fuel discharged from the pressure control chamber;
an in-orifice formed in the high pressure passage configured to restrict flow rate of the fuel supplied into the pressure control chamber;
a movable plate movably accommodated in the pressure control chamber, the movable plate being configured to be brought into contact with the fixed plate so as to block off communication between the high pressure passage and the pressure control chamber or the movable plate being configured to be separated from the fixed plate so as to communicate the high pressure passage to the pressure control chamber, and the movable plate having a through-hole configured to communicate the pressure control chamber to the low pressure passage;
a control valve configured to open and close an outlet port of the low pressure passage; and
an electric actuator configured to open the control valve when electric power is supplied to the electric actuator,
wherein the fuel injection system has an electronic control unit configured to control power supply to the electric actuator in order to carry out multiple fuel injections for each combustion cycle of the internal combustion engine, and the electronic control unit comprises:
an injection-stop control portion configured to control a control-valve closing operation of the control valve in order to increase the control-chamber pressure and to thereby move the valve body to a valve-body closing position, so that a first fuel injection is terminated; and
an interval-shortening control portion configured to start a control-valve opening operation of the control valve even in a condition that the movable plate is still being separated from the fixed plate, when the control-chamber pressure is decreased in order to open the valve body so that a second fuel injection is carried out after the first fuel injection in the same combustion cycle of the internal combustion engine,
wherein flow rate of the sub out-orifice and flow rate of the in-orifice are so set that the control-chamber pressure is decreased when the control valve starts the control-valve opening operation for the second fuel injection by the interval-shortening control portion,
the flow rate of the sub out-orifice and the flow rate of the in-orifice are so set that a pressure difference between a steady pressure and a valve-body opening pressure is controlled at a value within a predetermined range,
the steady pressure is a pressure of the pressure control chamber in a steady-state situation in which a fuel discharging amount via the sub out-orifice and a fuel supplying amount via the in-orifice are stable,
the valve-body opening pressure is a pressure of the pressure control chamber at which the valve body starts a valve-body opening operation, and
the interval-shortening control portion starts the control-valve opening operation of the control valve for the second fuel injection during a course in which the valve body is in its valve-body closing operation.

2. The fuel injection valve according to claim 1 , wherein
the flow rate of the sub out-orifice and the flow rate of the in-orifice are so set that the control-chamber pressure is not decreased to a valve-body opening pressure during a predetermined time period from a timing at which the control valve starts the control-valve opening operation by the interval-shortening control portion,
wherein the valve-body opening pressure is a pressure of the pressure control chamber, at which the valve body starts a valve-body opening operation.

3. The fuel injection valve according to claim 1 , wherein
the flow rate of the sub out-orifice and the flow rate of the in-orifice are so set that the steady pressure coincides with the valve-body opening pressure.

4. The fuel injection valve according to claim 1 , wherein
a cross sectional area of an outlet port of the low pressure passage is made larger than that of the sub-out-orifice.

5. The fuel injection valve according to claim 1 , wherein
the electronic control unit has a normal control portion for starting the control-valve opening operation of the control valve in a condition that the movable plate is in contact with the fixed plate, so as to carry out fuel injection by decreasing the control-chamber pressure and thereby opening the valve body, and
the electronic control unit switches the control-valve opening operation by the normal control portion to the control-valve opening operation by the interval-shortening control portion, depending on a target value of a fuel injection interval.

Assignees

• Denso Corp

Inventors

• Adachi Naofumi

Classifications

• F02M55/008

  Arrangement of fuel passages inside of injectors · CPC title

• F02M51/06 Primary

  Injectors peculiar thereto {with means directly operating the valve needle} · CPC title

• F02M47/027 Primary

  Electrically actuated valves draining the chamber to release the closing pressure · CPC title

• F02M63/0007 Primary

  using electrically actuated valves (injection valves F02M51/06) · CPC title

• F02M63/0054

  Check valves (F02M59/462, F02M59/464 take precedence) · CPC title