AN ARRANGEMENT FOR PROTECTING A HIGH-PRESSURE ACCUMULATOR FUEL INJECTION SYSTEM

Abstract

A system for protecting a high-pressure accumulator fuel injection system of an internal combustion engine against excessively high fuel pressures occurring in a high-pressure accumulator of the fuel injection system caused by a malfunction in the fuel injection, wherein the system comprises a member measuring the fuel pressure inside the high-pressure accumulator and sending information about this pressure to a control unit. An electrically controllable inlet valve to a pumping element of a high-pressure pump is included in the system and controlled by the control unit to be transferred to a continuously open or closed state, if the pressure measured exceeds a predetermined pressure level for stopping the feeding of fuel by the pumping element to the high-pressure accumulator.

Claims

1. A system for protecting a high-pressure accumulator fuel injection system of an internal combustion engine against excessively high fuel pressures occurring in a high-pressure accumulator of the fuel injection system caused by a malfunction in the fuel injection system, where the fuel injection system comprises: the high-pressure accumulator, a high-pressure pump with at least one pumping element configured to feed fuel to the high-pressure accumulator, at least one injector connected to the high-pressure accumulator for injecting fuel into a cylinder of the engine, an electrically controllable inlet valve arranged in a fuel line to each of said at least one pumping element and controllable to open and close when energized, said system comprising: at least one first member configured to measure a fuel pressure inside the high-pressure accumulator; a control unit configured to compare the value of said pressure measured by said at least one first member with a predetermined pressure level and control energization of the inlet valve to stop and transfer the inlet valve to a continuously closed or open state and stop feeding of fuel by the pumping element to the high-pressure accumulator, when the value of the pressure measured exceeds said predetermined pressure level; and an irreversible valve arranged in a fuel return line from the high-pressure accumulator to a fuel reservoir container, wherein said irreversible valve is configured to be closed at a normal operation of said fuel injection system and to transition to an irreversible open state when a pressure in the high-pressure accumulator exceeds the predetermined level, so as to form a bypass passing the injector and draining fuel from the high-pressure accumulator to the fuel reservoir container, thereby reducing the pressure inside the high-pressure accumulator.

2. A system according to claim 1, wherein said irreversible valve comprises at least one second member, configured to break when a fuel pressure above a predetermined level acts on the second member and when broken, makes the irreversible valve irreversibly open.

3. A system according to claim 1, further comprising two said first members configured to measure the fuel pressure inside the high-pressure accumulator and to send information about the pressure measured to said control unit, whereby the two said first members provide redundancy.

4. A system according to claim 1, wherein the control unit is configured to compare said pressure measured with said predetermined pressure level, where said predetermined pressure level exceeds a normal operation fuel pressure in the high-pressure accumulator by a value of 10%-50%.

5. A system according to claim 1, wherein the irreversible valve is configured to transition to an irreversible open state when a pressure in the high-pressure accumulator is above a predetermined level, where said predetermined pressure level is a value that exceeds a normal operation fuel pressure in the high-pressure accumulator by a value of 10%-50%.

6. (canceled)

7. (canceled)

8. A system according to claim 1, wherein the control unit is configured to compare said pressure measured with said predetermined pressure level, where said predetermined pressure level exceeds a normal operation fuel pressure in the high-pressure accumulator by a value of 10%-30%.

9. A system according to claim 1, wherein the irreversible valve is configured to transition to an irreversible open state when a pressure in the high-pressure accumulator is above a predetermined level, where said predetermined pressure level is a value that exceeds a normal operation fuel pressure in the high-pressure accumulator by a value of 10%-30%.

10. An internal combustion engine comprising at least one cylinder and a system for protecting a high-pressure accumulator fuel injection system of the internal combustion engine against excessively high fuel pressures occurring in a high-pressure accumulator of the fuel injection system caused by a malfunction in the fuel injection system, where the fuel injection system comprises: the high-pressure accumulator, a high-pressure pump with at least one pumping element configured to feed fuel to the high-pressure accumulator, at least one injector connected to the high-pressure accumulator for injecting fuel into a cylinder of the engine, an electrically controllable inlet valve arranged in a fuel line to each of said at least one pumping element and controllable to open and close when energized, said system comprising: at least one first member configured to measure a fuel pressure inside the high-pressure accumulator; a control unit configured to compare the value of said pressure measured by said at least one first member with a predetermined pressure level and control energization of the inlet valve to stop and transfer the inlet valve to a continuously closed or open state and stop feeding of fuel by the pumping element to the high-pressure accumulator, when the value of the pressure measured exceeds said predetermined pressure level; and an irreversible valve arranged in a fuel return line from the high-pressure accumulator to a fuel reservoir container, wherein said irreversible valve is configured to be closed at a normal operation of said fuel injection system and to transition to an irreversible open state when a pressure in the high-pressure accumulator exceeds the predetermined level, so as to form a bypass passing the injector and draining fuel from the high-pressure accumulator to the fuel reservoir container, thereby reducing the pressure inside the high-pressure accumulator.

11. A motor vehicle comprising: an internal combustion engine comprising at least one cylinder; and a system for protecting a high-pressure accumulator fuel injection system of the internal combustion engine against excessively high fuel pressures occurring in a high-pressure accumulator of the fuel injection system caused by a malfunction in the fuel injection system, where the fuel injection system comprises: the high-pressure accumulator, a high-pressure pump with at least one pumping element configured to feed fuel to the high-pressure accumulator, at least one injector connected to the high-pressure accumulator for injecting fuel into a cylinder of the engine, an electrically controllable inlet valve arranged in a fuel line to each of said at least one pumping element and controllable to open and close when energized, said system comprising: at least one first member configured to measure a fuel pressure inside the high-pressure accumulator; a control unit configured to compare the value of said pressure measured by said at least one first member with a predetermined pressure level and control energization of the inlet valve to stop and transfer the inlet valve to a continuously closed or open state and stop feeding of fuel by the pumping element to the high-pressure accumulator, when the value of the pressure measured exceeds said predetermined pressure level; and an irreversible valve arranged in a fuel return line from the high-pressure accumulator to a fuel reservoir container, wherein said irreversible valve is configured to be closed at a normal operation of said fuel injection system and to transition to an irreversible open state when a pressure in the high-pressure accumulator exceeds the predetermined level, so as to form a bypass passing the injector and draining fuel from the high-pressure accumulator to the fuel reservoir container, thereby reducing the pressure inside the high-pressure accumulator.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0017] With reference to the appended drawings, below follows a specific description of an embodiment of the invention cited as an example.

[0018] In the drawings:

[0019] FIG. 1 is a schematic view illustrating an arrangement for protecting a high-pressure accumulator fuel injection system of an internal combustion engine according to an embodiment of the invention,

[0020] FIG. 2 is a flow chart illustrating the steps of a method according to the invention, and

[0021] FIG. 3 illustrates schematically an electronic control unit according to the invention.

DETAILED DESCRIPTION OF THE INVENTION

[0022] FIG. 1 illustrates schematically the general structure of a high-pressure accumulator fuel injection system of an internal combustion engine arranged in a motor vehicle 1 according to an embodiment of the invention. The high-pressure accumulator fuel injection system is provided with fuel from a fuel reservoir container 2 fed therethrough by a low-pressure feeder pump 3 through filters 4 and 5. A high-pressure pump 6 may have a plurality of pumping elements, normally 2 or 3, but only one 7 is shown here. An electrically controllable inlet valve 8 is arranged in a fuel line 9 to each pumping element 7.

[0023] An electronic control unit 10 is configured to control the open degree of said inlet valve 8 by the degree or energization thereof, and the inlet valve is configured to need a supply of voltage from the control unit either for open or closing at all depending upon whether the inlet valve is of the type normally closed or normally open, so that it will either close or open the fuel supply to the pumping element 7 of the high-pressure pump would the supply of voltage thereto be interrupted.

[0024] The pumping element 7 will when supplied by fuel from the container 2 through the feeder pump 3 rise the pressure of the fuel and pump fuel through an outlet valve 11 to a high-pressure accumulator 12 (rail) in common to all the cylinders of said internal combustion engine. In the case of a normally open inlet valve 8 this has of course to be energized to close under a part of the pumping stroke of the pumping element 7 for enabling pumping. The pressure of the fuel inside the high-pressure accumulator is for a motor vehicle in the form of a truck typically in the order of 2 000 bar. One injector 13 for each cylinder of said engine is connected to the high-pressure accumulator 12 for being controlled to inject fuel into said cylinder where the fuel is combusted to provide power, such as to a vehicle.

[0025] It is shown how two members 14, 15 are provided for measuring the fuel pressure inside the high-pressure accumulator 12 and to send information about the pressure measured to the control unit 10. The control unit 10 is configured to compare the values of this pressure measurement with a predetermined pressure level and if one of these values exceeds said predetermined level the control unit will stop the supply of voltage to said inlet valves and by that transfer these valves to a continuously closed or open state, so that feeding of fuel by the pumping element to the high-pressure accumulator will be stopped.

[0026] An irreversible valve 16 is arranged in a fuel return line 17 from the high-pressure accumulator 12 to the fuel reservoir container 2 and is configured to be closed at normal operation of the system. However, this irreversible valve comprises a member 18, such as a rod, breaking as of a pressure in the high-pressure accumulator above a predetermined level acting thereupon and when broken making the irreversible valve 16 irreversibly open so as to form a bypass passing the injector 13 and draining fuel from the high-pressure accumulator to the fuel reservoir container and by that reducing the pressure inside the high-pressure accumulator.

[0027] FIG. 2 illustrates a flow chart of a method according to an embodiment of the present invention carried out for protecting a high-pressure accumulator fuel injection system of an internal combustion engine of the type shown in FIG. 1 against excessively high fuel pressures to result in a high-pressure accumulator of that system as a consequence of occurrence of a malfunction in the system. The method is started with a step S1 of measuring the fuel pressure inside the high-pressure accumulator, whereupon in a step S2 the value of the pressure measured is compared with a predetermined level thereof and the question is asked whether the value exceeds said predetermined level. If the answer to this question is yes it is continued with a step S3 of controlling energization of the inlet valve to the pumping element of the high-pressure pump to stop.

[0028] Computer program code for implementing a method according to the invention is with advantage included in a computer program, which can be read into the internal memory of a computer, e.g. the internal memory of an electronic control unit of a motor vehicle. Such a computer program is with advantage provided via a computer program product comprising a data storage medium, which can be read by a computer and which has the computer program stored on it. Said data storage medium is for example an optical data storage medium in the form of a CD ROM disc, a DVD disc etc., a magnetic data storage medium in the form of a hard disc, a diskette, a cassette tape etc., or a flash memory or a memory of the ROM, PROM, EPROM or EEPROM type. FIG. 3 illustrates very schematically an electronic control unit 10 comprising an execution means 19, e.g. a central processor unit (CPU), for execution of computer software. The execution means 19 communicates with a memory 20, e.g. of the RAM type, via a data bus 21. The control unit 18 comprises also a non-transitory data storage medium 22, e.g. in the form of a flash memory or a memory of the ROM, PROM, EPROM or EEPROM type. The execution means 19 communicates with the data storage medium 22 via the data bus 21. A computer program comprising computer program code for implementing a method according to the invention, e.g. in accordance with the embodiment illustrated in FIG. 2, is stored on the data storage medium 22.

[0029] The invention is of course in no way restricted to the embodiments described above, since many possibilities for modifications thereof are likely to be obvious to one skilled in the art without having to deviate from the scope of invention defined in the appended claims.