# US 7,461,795 B2 · Fuel injection system for internal combustion engines

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- Number: US 7,461,795 B2
- Document ID: US7461795B2
- Status: Granted
- Kind: B2
- Application number: 10/532,493
- Filed: 2003-06-30
- Published: 2006-03-09
- Granted: 2008-12-09
- Earliest claimed: 2002-10-25
- Assignees: Robert Bosch GmbH
- Inventors: Hans-Christoph Magel
- Web page: https://patentgrep.com/patent/US7461795B2

## CPC

- F02M 57/026: {Construction details of pressure amplifiers, e.g. fuel passages or check valves arranged in the intensifier piston or head, particular diameter relationships, stop members, arrangement of ports or conduits}
- F02M 47/027: {Electrically actuated valves draining the chamber to release the closing pressure}
- F02M 57/025: {hydraulic, e.g. with pressure amplification}
- F02M 59/105: {hydraulic drive (F02M59/32 takes precedence)}
- F02M 63/0225: {Fuel-injection apparatus having a common rail feeding several injectors (F02M63/0003 takes precedence); Means for varying pressure in common rails; Pumps feeding common rails}
- F02M: SUPPLYING COMBUSTION ENGINES IN GENERAL WITH COMBUSTIBLE MIXTURES OR CONSTITUENTS THEREOF

## Abstract

A fuel injection system for internal combustion engines, having a fuel injection nozzle supplied with fuel by a high-pressure fuel source, which fuel injection nozzle has a movable nozzle piston for opening and closing injection openings, an injection nozzle high-pressure chamber, and an injection nozzle control chamber. A pressure boosting device connected between the fuel injection nozzle and the high-pressure fuel source has a movable piston, a work chamber, and a high-pressure chamber, in which a filling connection which is open for filling the high-pressure chamber when the fuel injection nozzle is closed and is itself closed when the fuel injection nozzle is open.

## Claims

### Claim 1

A fuel injection system for internal combustion engines, comprising
a fuel injection nozzle (2), which can be supplied with fuel by a high-pressure fuel source (1), the fuel injection nozzle (2) having a movable nozzle piston (3) for opening and closing injection openings (6), an injection nozzle high-pressure chamber (21), an injection nozzle control chamber (20), and a closing spring located within the control chamber (20) for biasing the nozzle piston (3) in a direction to close the injection openings (6),
a pressure boosting device (7) is connected between the fuel injection nozzle (2) and the high-pressure fuel source (1), the pressure boosting device (7) having a movable pressure booster piston (8), a pressure booster work chamber (11), and a pressure booster high-pressure chamber (9), and
a filling connection (10) which is open for filling the pressure booster high-pressure chamber (9) when the fuel injection nozzle (2) is closed and is itself closed by the nozzle piston (3) when the fuel injection nozzle (2) is open, said filling connection (10) including a throttle (23),
wherein closure of the filling connection (10) is coupled with the motion of the nozzle piston (3) in the opening direction to uncover the injection openings, and
wherein the control chamber (20) is hydraulically connected to the pressure booster high-pressure chamber (9) by the filling connection (10).

### Claim 2 (depends on 1)

The fuel injection system of claim 1, wherein a pressure change in a pressure booster control chamber (12) contained in the pressure boosting device (7) and/or in the pressure booster work chamber (11) causes a pressure change in the pressure booster high-pressure chamber (9).

### Claim 3 (depends on 2)

The fuel injection system of claim 2, wherein the pressure booster high-pressure chamber (9) communicates, when the fuel injection nozzle (2) is closed, with the high-pressure fuel source (1) via a control valve (14) (in a first switching position (15)), the pressure booster control chamber (12), the injection nozzle control chamber (20), and the filling connection (10).

### Claim 4 (depends on 2)

The fuel injection system of claim 2, wherein when the fuel injection nozzle (2) is opening and is open, the pressure booster control chamber (12) and the injection nozzle control chamber (20) communicate with a low-pressure line (17).

### Claim 5 (depends on 2)

The fuel injection system of claim 2, wherein when the fuel injection nozzle (2) is closed, the pressure booster high-pressure chamber (9), via the filling connection (10), and via the injection nozzle control chamber (20), the pressure booster control chamber (12) and the pressure booster work chamber (11) communicate with at least one low-pressure line (17, 48, 49).

### Claim 6 (depends on 1)

The fuel injection system of claim 1, further comprising a control valve (14) operable to control the opening and closing of the injection openings (6) are controllable via a control valve (14).

### Claim 7 (depends on 1)

The fuel injection system of claim 1, wherein the high-pressure fuel source (1) communicates during the injection, via a high-pressure line (27), with the pressure booster work chamber (11) contained in the pressure boosting device (7).

### Claim 8 (depends on 1)

The fuel injection system of claim 1, wherein the filling connection (10) is closable by the cooperation of the nozzle piston (3) with a sealing seat (26).

### Claim 9 (depends on 1)

The fuel injection system of claim 1, further comprising a sealing seat (26) embodied on the nozzle piston (3) and cooperating with a pressure piece (45) for closing the filling connection (10).

### Claim 10 (depends on 1)

The fuel injection system of claim 1, wherein the filling connection (10) is embodied in the nozzle piston (3).

### Claim 11 (depends on 1)

The fuel injection system of claim 1, wherein the injection nozzle control chamber (20) is located in the pressure booster piston (8), and wherein the pressure booster piston (8) is embodied as a hollow piston.