Fuel injection apparatus having fuel supplier for displacement amplifying chamber

• US 20070079807A1
• Filed: 10/12/2006
• Published: 04/12/2007
• Est. Priority Date: 10/12/2005
• Status: Active Grant

• Current Assignee: DENSO Corporation
• Original Assignee: DENSO Corporation
• Inventors: Toyoshima, Yoshio
• Granted Patent: US 7,520,267 B2
• Time in Patent Office: Days
• US Class Current: 123/446
• CPC Class Codes: F02M 57/025 hydraulic, e.g. with pressure amplification
• CPC Class Codes: F02M 59/105 hydraulic drive F02M59/32 takes precedence
• CPC Class Codes: F02M 63/0026 using piezoelectric or magnetostrictive actuators

Abstract

According to the present invention, a fuel injection apparatus includes a high-pressure passage, a low-pressure passage, an actuator, a first and a second piston, a displacement amplifying chamber, a fuel injection mechanism, and a fuel supplier. The high-pressure passage is configured to be filled with high-pressure fuel. The low-pressure passage is configured to be filled with low-pressure fuel. The first piston is configured to be displaced by the actuator. The displacement amplifying chamber communicates with the low-pressure passage and works to amplify and transmit to the second piston a displacement of the first piston by means of the low-pressure fuel therein. The fuel injection mechanism is configured to inject the high-pressure fuel into a cylinder of an internal combustion engine in response to the displacement of the second piston. The fuel supplier works to supply the high-pressure fuel from the high-pressure passage through pressure reduction directly to the low-pressure passage.

Claims

1. A fuel injection apparatus comprising:

a high-pressure passage configured to be filled with high-pressure fuel;

a low-pressure passage configured to be filled with low-pressure fuel;

an actuator;

a first piston configured to be displaced by the actuator;

a second piston;

a displacement amplifying chamber communicating with the low-pressure passage, the displacement amplifying chamber working to amplify and transmit to the second piston a displacement of the first piston by means of the low-pressure fuel therein;

a fuel injection mechanism configured to inject the high-pressure fuel into a cylinder of an internal combustion engine in response to the displacement of the second piston; and

a fuel supplier working to supply the high-pressure fuel from the high-pressure passage through pressure reduction directly to the low-pressure passage, thereby minimizing a time required to fill up the displacement amplifying chamber with the low-pressure fuel after start of the engine.

2. The fuel injection apparatus as set forth in claim 1, wherein the fuel supplier is configured with:

a first regulating valve working to regulate pressure of the high-pressure fuel to a first predetermined pressure;

a supply passage hydraulically connecting the first regulating valve to the low-pressure passage; and

a second regulating valve working to regulate pressure of the low-pressure fuel to a second predetermined pressure.

3. The fuel injection apparatus as set forth in claim 2, wherein the fuel injection apparatus is incorporated in a common rail fuel injection system for a diesel engine, and the high-pressure passage communicates with a common rail of the system.

4. The fuel injection apparatus as set forth in claim 3, wherein the first regulating valve is a pressure reducing valve that is installed to the common rail to regulate fuel pressure in the common rail.

5. The fuel injection apparatus as set forth in claim 2, wherein the second regulating valve is a check valve that is hydraulically connected to the low-pressure passage.

6. The fuel injection apparatus as set forth in claim 1, wherein the low-pressure passage is also configured to receive leak fuel from the high-pressure passage.

7. The fuel injection apparatus as set forth in claim 1, wherein the fuel injection mechanism is configured with:

a casing;

a pressure chamber formed within the casing;

a control valve configured to be actuated by the second piston to control fuel pressure in the pressure chamber;

a fuel sump formed within the casing, the fuel sump communicating with the high-pressure passage;

at least one injection hole formed through the casing to communicate with the fuel sump; and

a nozzle needle configured to be moved within the casing in accordance with the fuel pressure in the pressure chamber to selectively open and close the injection hole.