Fuel injection system and controller for fuel injection system

Patent metadata

Field	Value
Publication number	US-11261820-B2
Application number	US-202016936753-A
Country	US
Kind code	B2
Filing date	Jul 23, 2020
Priority date	Jul 30, 2019
Publication date	Mar 1, 2022
Grant date	Mar 1, 2022

Abstract

A fuel pump includes a camshaft that rotates in accordance with operation of an engine and a tappet provided in contact the camshaft. An ECU includes an angle determination unit configured to determine whether a rotation angle from a start of rotation of the camshaft when starting the engine is under a predetermined angle required for forming an oil film on a sliding portion of the tappet, and a control unit configured to, when the rotation angle from the start of rotation of the camshaft is determined to be under the predetermined angle, execute a limit process including at least one of limiting a fuel discharge pressure of the fuel pump or limiting a rotation of the camshaft.

First claim

The invention claimed is:

1. A controller for a fuel injection system including a fuel pump having a camshaft that rotates in accordance with operation of an internal combustion engine, a tappet provided in contact with a cam of the camshaft that converts the rotation of the camshaft into linear motion, and a plunger that reciprocates according to the linear motion of the tappet, the fuel pump being configured to suck and discharge fuel according to the reciprocation of the plunger, an accumulator that stores high pressure fuel discharged from the fuel pump, and a fuel injection valve that injects the high pressure fuel stored in the accumulator into a combustion chamber of the internal combustion engine, the controller comprising:
an angle determination unit configured to determine whether a rotation angle from a start of rotation of the camshaft when starting the internal combustion engine is under a predetermined angle required for forming an oil film on a sliding portion of the tappet, and
a control unit configured to:
when the rotation angle from the start of rotation of the camshaft is determined to be under the predetermined angle, execute a limit process including at least one of limiting a fuel discharge pressure of the fuel pump or limiting a rotation of the camshaft, and
when the rotation angle is determined to have exceeded the predetermined angle after having executed the limit process, cancel the limit process execution.

2. The controller for the fuel injection system according to claim 1 , wherein
the control unit is configured to:
limit the fuel discharge pressure of the fuel pump by performing any one of: stopping the fuel discharge of the fuel pump, decreasing a fuel discharge amount of the fuel pump, and discharging the fuel in the accumulator to reduce fuel pressure, and
limit the rotation of the camshaft by performing any one of: stopping the fuel injection of the fuel injection valve, reducing a fuel injection amount of the fuel injection valve, and limiting a rotation of a starter device that applies an initial rotation to the internal combustion engine when starting the internal combustion engine.

3. The controller for the fuel injection system according to claim 1 , further comprising:
a calculation unit configured to, after initiating the starting of the internal combustion engine, calculate a rotation speed peak value for each combustion according to the fuel injection of the fuel injection valve, wherein
the control unit limits the rotation of the camshaft based on the rotation speed peak value calculated by the calculation unit.

4. The controller for the fuel injection system according to claim 1 , further comprising:
a pressure acquisition unit configured to, after initiating the starting of the internal combustion engine, acquire the fuel pressure in the accumulator for each fuel discharge of the fuel pump, wherein
the control unit limits the rotation of the camshaft based on the fuel pressure acquired by the pressure acquisition unit.

5. The controller for the fuel injection system according to claim 1 , wherein
the cam has n cam ridges,
the tappet includes a roller that abuts on a cam surface of the cam, and a shoe having a concave portion for accommodating the roller and rotatably supporting the roller in the concave portion, wherein
the angle determination unit is configured to determine whether or not the rotation angle of the camshaft from the start of rotation is under a predetermined angle defined within a range of “0.5×360 degrees/n” to “2×360 degrees/n”.

6. The controller for the fuel injection system according to claim 1 , wherein
the cam has n cam ridges,
the tappet includes a roller that abuts on a cam surface of the cam, and a shoe having a concave portion for accommodating the roller and rotatably supporting the roller in the concave portion, wherein
the angle determination unit is configured to determine whether or not the rotation angle of the camshaft from the start of rotation is under a predetermined angle defined as “1.5×360 degrees/n”.

7. The controller for the fuel injection system according to claim 1 , wherein
the fuel injection system is applied to a vehicle having, as starter devices for the internal combustion engine, a first motor and a second motor having an initial rotation speed higher than that of the first motor, the controller further comprising:
a start determination unit configured to, when the internal combustion engine is being started, determine whether the engine is being started by the first motor or started by the second motor, and
a second control unit configured to prohibit the limit process from being executed when the engine is being started by the first motor, and to permit the limit process from being executed when the engine is being started by the second motor.

8. A fuel injection system for an internal combustion engine, comprising:
a fuel pump including:
a camshaft that rotates in accordance with operation of the internal combustion engine,
a tappet provided in contact with a cam of the camshaft that converts the rotation of the camshaft into linear motion, and
a plunger that reciprocates according to the linear motion of the tappet, the fuel pump being configured to suck and discharge fuel according to the reciprocation of the plunger;

an accumulator that stores the fuel discharged from the fuel pump;
a fuel injection valve that injects the fuel stored in the accumulator into a combustion chamber of the internal combustion engine; and
an electronic control unit including a processor and a memory, the memory having stored thereon instructions which when executed by the processor causes the processor to:
determine whether a rotation angle from a start of rotation of the camshaft when starting the internal combustion engine is under a predetermined angle required for forming an oil film on a sliding portion of the tappet,
upon determining that the rotation angle from the start of rotation of the camshaft is under the predetermined angle, execute a limit process including at least one of limiting a fuel discharge pressure of the fuel pump or limiting a rotation of the camshaft, and
upon determining that the rotation angle is greater than the predetermined angle after having executed the limit process, cancel the limit process execution.

Assignees

• Denso Corp

Inventors

• Ishikawa Tamaki

Classifications

• F02D2250/31

  Control of the fuel pressure · CPC title

• F02D2200/0602

  Fuel pressure · CPC title

• F02M59/447

  means specially adapted to limit fuel delivery or to supply excess of fuel temporarily, e.g. for starting of the engine (combined with fuel pump regulating devices F02D) · CPC title

• F02M59/36

  by variably-timed valves controlling fuel passages {to pumping elements or overflow passages} · CPC title

• F02D41/3863 Primary

  by controlling the flow out of the common rail, e.g. using pressure relief valves · CPC title