CN1625650A - Fuel injection system - Google Patents

Abstract

A fuel injection system for an internal combustion engine includes a nozzle (2) having an inlet and a cam-driven plunger (5) forming a plunger chamber (7) connected to the inlet of the nozzle. The injection system also includes a common rail (10) for fuel and a control valve (9) mounted between the plunger chamber (7) and the common rail (10), wherein the control valve is capable of opening or closing the hydraulic connection between the plunger chamber and the common rail upon receiving an electronic control command. An electrically actuated nozzle control valve (21) is used to open and close the nozzle (2). The system also includes a device (11) for pressurizing the common rail and regulating the fuel pressure in the common rail (10).

Description

fuel injection system

technical field

The invention relates to a device for injecting fuel into an internal combustion engine, in particular a compression ignition engine.

Background technique

The most common devices for injecting fuel into modern diesel engines can be divided into two functionally distinct categories: mechanically actuated systems and common rail systems. Most high power diesel engines used in commercial vehicles employ mechanically actuated electronically controlled integral injector/unit pump systems. The small power diesel engine market is dominated by pump-to-nozzle in-line mechanically actuated fuel injection systems (FIE) or so-called high pressure common rail systems.

There are several types of mechanically actuated integral injectors/unit pumps and they all produce very high injection pressures with relatively good hydraulic/mechanical efficiency, which is one of their most important advantages over common rail systems one. Another important advantage is better durability, which is much less durable than mechanically actuated systems due to the continuous exposure of its components to the maximum oil pressure required for injection. Another important advantage of mechanically actuated integral injection systems is their inherent ability to achieve good injection rate improvements during a single injection. High pressure common rail systems cannot readily provide this injection characteristic, and modern integral injectors with direct nozzle control valves are equally capable of this when their inherently square injection curve pattern becomes desirable at some engine operating points. way to form the injection curve. This provides the integral injector system with greater flexibility in the shape of the injection rate curve.

On the other hand, high pressure common rail systems have certain advantages over mechanically actuated injection systems. Among the most important for commercial vehicle engines are virtually unlimited injection timing flexibility and easy implementation of multiple injections. This performance of fuel injection systems is important for the introduction of various types of diesel exhaust aftertreatment devices and for the advancement in the development of alternative combustion processes like HCCT. The reliance of mechanical actuation systems on a cam that drives the pump plunger can greatly limit their ability to meet the injection timing and fueling requirements of various injections. Another advantage of common rail systems over mechanically integrated injection systems may be lower parasitic drive power losses when operating at very low engine loads and idle speeds. In this case, the high-pressure common rail system can also have better fuel delivery accuracy than mechanically actuated integral injection systems with large plunger diameters. Finally, mechanically actuated integral injection systems can be a source of excessive mechanical noise generated by the FIE itself and the drivetrain transmitting torque to actuate the system. This excessive noise is especially noticeable when the engine is idling. The operation of the common rail system is not to add significantly to the overall engine noise at any point of operation.

Invention subject

The subject of the present invention is a new mechanically integrated injection system with common rail function. It is an object of the present invention to enable the mechanical injection actuation and common rail principles to be selectively used in situations where their respective advantages are allowed to be exploited, and to be selectively disabled in other situations where their respective disadvantages may adversely affect engine performance.

prior art review

US Patent 6,247,450 B1 to Jiang discloses a system consisting of mechanically actuated integral injectors with a control valve and a common rail. In this system, the common rail pressure is regulated at a lower level and fuel at this pressure can be supplied to the integral injector through a metering orifice located somewhere in the plunger of the integral injector. It is open in one retracted position and closed in the other plunger position. The change in rail pressure and the opening duration of the metering orifice determine the amount of fuel that fills the plunger cavity. During the pumping stroke of the plunger, the metering orifice is closed and fuel is pressurized in the plunger cavity which is sized to allow the desired injection pressure to be achieved. The plunger chamber is connected to the inlet of a conventional spring-closed nozzle via a control valve. When the required pressure level is reached, the control valve can be opened to deliver pressurized fuel to the nozzles and start injection. To end the injection, the valve is closed, whereupon the nozzle is closed by the return spring.

Such systems provide flexibility in injection timing by relying on a plunger that rests at maximum lift and maintains the pressure built up during the pumping stroke. Fuel injection may not occur during most of the retraction and pumping strokes of the plunger because the metering orifice is closed. Apparently the system is not designed to inject at any other time than when the plunger is near maximum lift, because even though the control valve is opened during the fuel metering phase and the rail pressure is set above the nozzle's spring opening pressure , the pressure drop across the metering orifice, which is necessary for the fuel metering function of the system, will also prevent injection.

In addition to the limited range of injection timings, the system of US Patent 6247450 has a number of other disadvantages, namely the unfavorable shape of the injection rate curve at the start and end of injection, the limited range of injection pressures, etc.

Another prior art FIE that may be considered relevant to the present invention is the system introduced to the market by Cummins Corporation known as the pressure/time metered unit injection system. Examples of such systems can be found in US Patents 3,544,008, 4,092,964 and 5,445,323. This type of system consists of a common rail supply unit injector for pressurized fuel. However, the function of the common rail is not to inject fuel directly into the engine, but to assist in the metering of fuel into the plunger cavity, the metered fuel being expelled through the nozzle during the pumping stroke of the plunger. Thus, such systems have a limited range of injection timing and require the application of mechanical actuation each time an injection is due.

Contents of the invention

It is a primary object of the present invention to provide a fuel injection system which enables the mechanical injection actuation and common rail principles to be selectively used when allowing their respective advantages to be exploited, and to be selectively deactivated otherwise to avoid them. Each has its own shortcomings.

A more specific object of the present invention is to provide a fuel injection system in which the range of possible injection timings is enlarged compared to known mechanically actuated injection systems so that injection can be performed at any point in the engine rotation Occurrence; Compared with the feasible injection pressure range of known high-pressure common rail systems, its possible injection pressure range is enlarged; and has an enhanced injection rate formation capability. This system allows the sole use of the common rail principle at idle speed and low load to reduce engine noise, and allows the sole use of the mechanical actuation principle when high injection pressure is required, thus making the design of the common rail part of the system relatively Relatively simple and durable due to low maximum feedline pressure. Use of both operating principles by selecting appropriate control valve energization timing, in addition to known mechanically actuated integral injectors and common rail systems may have other types of injection rate profile shapes such as square or triangular injection rates Curve, pilot injection, high-pressure after-injection and delayed after-injection, this system enables so-called "shoe" injection.

Another specific object of the present invention is to provide a fuel injection system which, in addition to the above features, inherently protects the system against overpressure.

Description of drawings

1 to 9 are diagrams of various embodiments of the invention.

Detailed ways

According to a first embodiment of the invention shown in FIG. 1, a fuel injector 1 is provided which combines a conventional normally closed nozzle 2 and an electrically operated nozzle control valve (NCV) 3; A mechanical actuating device 4 for pressurized fuel, comprising a cam-driven plunger 5 with a cam 6 and a plunger cavity 7, a return spring 8 and an electrically operated valve 9; one usually serving a set of said fuel A common rail 10 for the injectors and a mechanical actuation device in the engine (not shown), a device 11 for boosting the common rail and regulating the pressure in the common rail at the desired level; a return with a lower pressure Oil pipeline 12 and a fuel tank 13. An electronic control unit (not shown) controls the pressure in the common rail 10 and controls the valves 3 and 9 .

The fuel injector 1 is designed to work like a high pressure common rail injector of the type known from the prior art. As this known injector generally behaves, the injector 1 comprises a spring 14 biasing the spool 15 to close the nozzle 2; a control piston 16 having a control chamber 17 arranged so that in the control The higher pressure in the chamber tends to force the control piston to push the spool 15 to close the nozzle; inlet throttle 18 and outlet 19 . The input throttling member 18 is connected to the control chamber 17 and the plunger chamber 7, while the oil outlet 19 is connected to the control chamber and the NCV3. Upon receiving a command, the NCV can open and connect the outlet port 19 to the return line 12 . The flow areas of the meter-in, outlet and NCV are selected such that opening of the NCV causes a pressure drop in the control chamber which is sufficient for the pressure acting on the differential area of the spool 15 to open the nozzle 2 . Also like the commonly known high-pressure common rail injectors, the oil outlet 19 and the control piston 16 are designed in such a way that the control piston can limit the oil outlet in a position corresponding to the open nozzle, thereby limiting the pressurized fuel through the input Throttle 18 , oil outlet 19 and open control valve 3 leak into return line 12 .

The plunger chamber 7 is connected to the inlet of the nozzle 2 . Depending on the state of the control valve 9, the plunger chamber can be connected or disconnected from the common rail 10.

The fuel injection system works as follows: The fuel pressure in the common rail 10 is maintained at a certain constant level, which is set according to the requirements of the specific operating conditions of the engine. When the injection does not require very high injection pressures, eg for an engine running at idle or at relatively low load points, the control valve 9 remains open throughout the entire engine cycle. During the pumping stroke of the plunger 5, the fuel is drained back to the common rail through the control valve 9, so that there is little pressure increase in the plunger chamber 7, and correspondingly, the engine transmission driving the plunger is not subjected to much torsional vibration. To start injection, NCV3 opens and the pressure in the control chamber 17 drops causing the control piston 16 and spool 15 to lift and open the nozzle. Fuel is then injected through the open nozzles at common rail pressure until the NCV closes again. As the NCV is closed, the pressure in the control chamber 17 rises to the level of the common rail pressure, and the control piston 16 assisted by the spring 14 closes the nozzle. This working mode is also called common rail mode or CR mode. It should be understood that for a working CR mode of operation, the difference between the pressures in the common rail 10 and the return line 12 should be greater than the spring opening pressure of the nozzle 2, which is determined by the preset pressure of the spring 14 as is known in the art. The magnitude of the differential area of the loaded and closed spool 15 is determined.

The CR mode of operation makes it possible to reduce the mechanical noise of the injection system by eliminating torsional vibrations and the quick release of the torsional-vibrated transmission, which drives the mechanical actuation device, which is mechanically actuated FIE especially integral The characteristics of the injector. The availability of common rail pressure also allows for fuel injection at any point in the engine cycle. The maximum design limit on working pressure in the common rail is a compromise between cost, service life and other parameters that limit the maximum pressure on the one hand, and flexibility such as injection timing, noise reduction and Additional benefits to improve engine characteristics. Thus, the maximum working pressure in a typical common rail can be between 200 and 600 bar.

When a higher injection pressure is required, the control valve 9 is temporarily closed during the pumping stroke of the plunger 5 , which increases the pressure in the plunger chamber 7 , at the inlet throttle 18 and at the inlet of the nozzle 2 . When a certain desired pressure is reached, the NCV opens and injection occurs as described above. The end of injection depends on the relative timing of closing the NCV and opening the control valve 9 . This mode of operation is similar to the sequence of action of electromechanically actuated integral injectors known in the prior art, and is also referred to as the EUI mode of operation. By operating in the EUI mode, the invention enables the very high injection pressures that are characteristic of known integral injector and unit pump systems. At the same time, the present invention does not have the disadvantages of high pressure common rail systems with very high pressures in the common rail and other volumes because the high pressure is kept to a relatively small volume by the closed control valve 9 . In fact, the common rail pressure may be reduced during the EUI mode of operation to a very low level, which is only sufficient to ensure reliable filling of the plunger chamber 7 during the plunger retraction stroke, typically between 4 and 6 bar. between.

In another embodiment of the invention shown in FIG. 2, the system is configured in the same way design. The valve 20 opens during the return or retraction stroke of the plunger 5, reducing the pressure drop between the plunger chamber 7 and the common rail. The absence of valve 20 may result in the pressure at the inlet of nozzle 2 for the CR injection mode being too low to work, so valve 20 is used to allow injection to occur during the retraction stroke of the plunger. Alternatively, it allows the use of a control valve 9 with a smaller flow area, which in turn improves the response time of the control valve, reduces its size, reduces power consumption, etc.

When higher spool opening and closing speeds are required, the above principle of controlling the movement of the spool 15 may not be adequate, which can be overcome by using a three-way valve and appropriately changing the hydraulic circuit. 3 and 4 show another embodiment of the invention in which a three-way needle valve 3 is installed between the plunger chamber 7 and the control chamber 17 . The control chamber is only connected to the NCV, which can selectively connect the control chamber 17 to a pressure source (as shown in the figure) or to the return line 12 with low pressure. The opening of the NCV closes the connection of the control chamber to the pressure source and opens the connection of the oil return line, so that the fuel can be discharged quickly, making it possible to open the spool faster. Closing of the NCV disconnects the control chamber 17 from the return line and reconnects the control chamber 17 to the pressure source, which also closes the nozzle more quickly.

As with the embodiment shown in FIG. 2 , as shown in FIG. 4 , the check valve 20 can be used to expand the range of possible injection timings of the system and reduce the maximum necessary flow area of the control valve 9 , wherein the check valve 20 is connected by its inlet to the common rail and by its outlet to the nozzle 2 .

Yet another embodiment shown in FIG. 5 incorporates a three-position/three-way control valve 9 between the plunger chamber 7 and the common rail 10 . The control valve 9 can selectively connect the plunger chamber 7 to the common rail or to the return line 12, or isolate the plunger chamber from both. The other designs are the same as those shown in FIG. 3 . An advantage of configuring the invention according to the embodiment of FIG. 5 is that a so-called "spill end" of injection can be used where required.

By opening the NCV thereby releasing the pressure from the control chamber 17, which in turn causes the nozzle 2 to open, the CR mode of operation is then achieved. During injection in the CR mode, as shown in FIG. 5 , fuel is supplied from the common rail to the nozzles through the open control valve 9 . This position of the valve 9 is called the first position. Closing the NCV increases the pressure in the control chamber 17 and eventually closes the nozzle. Any fuel expelled by plunger 5 during pumping build-up is returned to the common rail through valve 9, which prevents significant excess pressure from being built up in the system, effectively eliminating torsional vibration and release of the plunger drive mechanism.

In the EUI mode of operation, the control valve 9 is switched from the first position to the second position during the pumping stroke of the plunger 5 . In the second position, the valve 9 isolates the plunger chamber 7 from the common rail and return line. The pressure in the system then increases, and when the desired pressure level is reached, the NCV opens causing the spool 15 to open the nozzle as described above. Fuel injection occurs under high pressure generated by the plunger. To end spraying, several options are available. Typically, the NCV closes to repressurize the control chamber 17 . If the back pressure of the injection is desired to end, the control valve 9 can remain closed in the second position for a time equal to the nozzle closing duration, or switch back to the first position. The nozzle is then closed under high pressure in the control chamber 17 which will help the return spring 14 to close the nozzle faster. If it is desired to end the spillage of the injection, the control valve 9 is switched to the third position, connecting the plunger chamber 7 to the return line 12 and isolating the plunger chamber 7 from the common rail. In this way, the nozzle is closed by the return spring 14 while the oil pressure in the nozzle is low.

If it is advantageous to use both the overflow end of injection and the back pressure end, then the NCV can be connected directly to the common rail, as shown in Figure 6. To end the injection, the NCV is switched into a position in which it closes the connection between the control chamber 17 and the return line 12 and connects the control chamber to the common rail. The control valve 9 is switched to the third position to relieve the pressure in the plunger chamber and the nozzle, and the spool 15 closes the nozzle under the combined action of the return spring 14 and the pressure in the control chamber 17 . In this embodiment of the invention, a relatively weak nozzle return spring 14 can be used, which enables a lower minimum rail pressure setting that can be used for CR mode of operation.

To reduce the complexity of the injection system shown in Figures 5 and 6, a two-way nozzle control valve can be used instead of the three-way valve, as shown in Figures 7 and 8. The sequence of action of the system according to Figures 7 and 8 corresponds to that of the system shown in Figures 5 and 6 respectively, the design and action of the two-way NCV arrangement being described in the previous part of this section.

The embodiments of the invention shown in Figures 6 and 8 may be advantageous because they inherently provide better protection of the system from overvoltage. This is because the inlet of the control chamber 17 is connected to the common rail (directly or via NCV) and not to the plunger chamber 7, as in other embodiments of the invention (Figs. 1-5, 7) and many prior art designs , the inlet of the control chamber 17 is connected to the plunger chamber 7 . In systems where the inlets of these control chambers 17 are connected to the plunger chamber 7, since the pressure increase occurs simultaneously in the nozzle and the control chamber 17, the pressure cannot open the nozzle, so that no overflow channel is left when the NCV opening fails Given the pressure generated during the pumping stroke of the plunger, this can cause severe mechanical damage to the FIE and the engine. As shown in Figures 6 and 8, connecting the control chamber 17 to the common rail imposes a hardware limit on the maximum pressure that can be achieved in the injector closing the nozzle, which pressure limit is determined by the preload of the return spring 14, The diameter of the control piston 16 is determined by the pressure in the common rail 10, which in turn can be easily limited by a safety valve.

This principle of hardware limitation of maximum pressure can be used in any of the other embodiments of the invention described above. An example of this is given in Figures 9a,b.

Yet another embodiment of the invention shown in FIG. 10 incorporates an electrically actuated nozzle control valve 21 which directly controls the position of the spool 15 of the nozzle 2 . The spool 15 can be mechanically connected to the movable armature 22 of the NCV3. In this embodiment, the CR and/or EUI working modes and their combination are implemented in the same manner as described above. The electrically actuated nozzle control valve 21 may be solenoid actuated or preferably piezo actuated to achieve fast and precise control of the position of the spool 15 .

All of the embodiments of the invention described herein can shape the injection rate profile of the injection event in several ways. By appropriately retarding the opening timing of NCV3 relative to the closing of control valve 9, a variable needle opening pressure (NOP) is achieved during the EUI mode of operation. For the variants shown in FIGS. 6 , 8 and 9 , by using a control piston 16 with a larger diameter than the spool 15 , a very high maximum NOP can be set. Choosing a higher NOP will give a more square injection rate curve, a lower NOP will gradually increase the pressure during injection and the curve will have a triangular shape.

It is known that various injections such as pilot injection, split injection and post injection are possible for EUI and CR fuel injection systems, different combinations of these various injections can also be realized by the present invention. Additionally, the present invention enables shoe jetting with variable pressure levels and variable shoe phase durations. To achieve this spray pattern, both CR and EUI modes of operation can be used within a single spray cycle, with the NCV open before the plunger's pumping stroke begins.

The means 11 for pressurizing the common rail 10 and regulating the fuel pressure can incorporate a fixed displacement pump and a pressure regulator which is essentially a controllable safety valve. The displacement of the pump is chosen such that the maximum required pressure in the CR can be achieved under any engine operating condition. When a lower pressure than achievable under certain conditions is required, the relief valve returns excess fuel from the pump outlet to the fuel tank. Alternatively, a variable displacement pump can be used so that the output of the pump can be adjusted under any operating conditions to maintain the desired CR pressure without opening the relief valve, which acts as a safety valve in such systems. The function of pressure relief valve. The use of variable displacement pumps can reduce power loss, but such pumps are usually more expensive than fixed displacement pumps. Other configurations of the device 11 can be used in the present invention, such as a fixed displacement pump driven by the engine through a variable ratio transmission, whether mechanical, hydromechanical or electric. In the latter case, the starter motor of the engine can be used for this purpose, thus avoiding the cost of adding a dedicated motor to the pump.

Although the invention has been disclosed in connection with preferred embodiments, it should be understood that there may be other embodiments which fall within the spirit and scope of the invention as defined by the appended claims.

Claims (16)

1. a fuel injection system that is used for internal-combustion engine comprises a nozzle (2) with inlet; A cam-actuated plunger (5) that forms plunger cavity (7), described plunger cavity is connected to the inlet of nozzle; A common rail (10) that is used for fuel oil; A control valve (9) that is installed between plunger cavity (7) and the common rail (10), when receiving an electronic control instruction, described control valve can open or close the hydraulic communication between plunger cavity and common rail; The nozzle control valve (21) that the electricity that is used to open and close nozzle (2) is actuated; One is used for pressure boosting common rail and regulates the device (11) of the fuel pressure of rail (10) altogether; With a fuel tank (13).

2. fuel injection system as claimed in claim 1, one of them one-way valve (20) are installed in described plunger cavity (7) and are total between the rail (10), and the inlet of described one-way valve is connected to common rail.

3. fuel injection system as claimed in claim 1, wherein said control valve (9) are connected to return line (12) with described plunger cavity (7) from common rail (10) isolation and with plunger cavity (7) when being in the 3rd position; When being in the second place, plunger cavity (7) is isolated from return line (12) and common rail (10); When being in primary importance, plunger cavity (7) is connected to common rail (10) from return line (12) isolation and with plunger cavity (7).

4. a fuel injection system comprises a nozzle (2) and a spool (15) with inlet; Bias voltage spool is with the elastic device (14) of shut-off nozzle; A control piston (16) that forms control chamber (17), this control chamber has an input throttling element (18) and an oil outlet (19), and described control piston trends towards control piston (16) is pushed on the spool with shut-off nozzle in abutting connection with the elevated pressures in spool (15) so that the control chamber (17); A cam-actuated plunger (5) that forms plunger cavity (7), described plunger cavity is connected to the inlet of input throttling element (18) and nozzle (2); A common rail (10) that is used for fuel oil; A control valve (9) that is installed between plunger cavity (7) and the common rail (10), when receiving an electronic control instruction, described control valve (9) can open or close the hydraulic communication between plunger cavity and common rail; One is installed in the oil outlet (19) of control chamber (17) and the nozzle control valve (3) between the return line (12)---and be NCV (3), described NCV can open or close the hydraulic communication between oil outlet (19) and return line (12); One is used for pressure boosting common rail and regulates the device (11) of the fuel pressure of rail altogether; A fuel tank (13); Described fuel injection system is characterised in that, the valid circulation area of described input throttling element (18), oil outlet (19) and NCV (3) and the power of elastic device (14) are so selected, promptly when the pressure at nozzle entrance place was lower than the maximum service pressure of common rail, opening of NCV can impel spool (15) to open nozzle.

5. fuel injection system as claimed in claim 4, one of them one-way valve (20) are installed in described plunger cavity (7) and are total between the rail (10), and the inlet of described one-way valve is connected to common rail.

6. fuel injection system as claimed in claim 4, wherein said control valve (9) are connected to return line (12) with described plunger cavity (7) from common rail (10) isolation and with plunger cavity (7) when being in the 3rd position; When being in the second place, plunger cavity (7) is isolated from return line (12) and common rail (10); When being in primary importance, plunger cavity (7) is connected to common rail (10) from return line (12) isolation and with plunger cavity (7).

7. as any the described fuel injection system in the claim 4 to 6, wherein said input throttling element (18) is connected to common rail (10) rather than is connected to plunger cavity (7).

8. as any the described fuel injection system in the claim 4 to 7, wherein said oil outlet (19) and control piston (16) are so designed, be that control piston (16) can limit the circulation area of oil outlet (19) corresponding to the position of opening nozzle (2) at one, thereby the fuel oil that limits supercharging leak into return line (12) by the NCV (3) that imports throttling element (18), oil outlet (19) and open.

9. a fuel injection system comprises a nozzle (2) and a spool (15) with inlet; A bias voltage spool (15) is with the elastic device (14) of shut-off nozzle (2); A control piston (16), this control piston form control chamber (17) and in abutting connection with spool (15), so that the elevated pressures in the control chamber (17) trends towards that control piston (16) is pushed to spool (15) and goes up with shut-off nozzle (2); A cam-actuated plunger (5) that forms plunger cavity (7), described plunger cavity is connected to the inlet of nozzle (2); A common rail (10) that is used for fuel oil; A control valve (9) that is installed between plunger cavity (7) and the common rail (10), when receiving an electronic control instruction, described control valve can open or close the hydraulic communication between plunger cavity and common rail; A nozzle control valve (3)---be NCV (3), when being in primary importance, described NCV can isolate described control chamber (17) and open hydraulic communication between described plunger cavity (7) and the control chamber (17) from a return line (12), and when being in the second place, described NCV can be connected to return line (12) from plunger cavity (7) isolation and with control chamber (17) hydraulic pressure with described control chamber (17); One is used for pressure boosting common rail (10) and regulates the device of the fuel pressure of rail altogether; A fuel tank (13); Described fuel injection system is characterised in that, when NCV (3) was in its second place, the pressure in the rail (10) can be set fully highly with the power that overcomes elastic device (14) and open nozzle (2) altogether.

10. fuel injection system as claimed in claim 9, one of them one-way valve (20) are installed in described plunger cavity (7) and are total between the rail (10), and the inlet of described one-way valve is connected to common rail.

11. fuel injection system as claimed in claim 9, wherein said control valve (9) when being in the 3rd position, are connected to return line (12) with described plunger cavity (7) from common rail (10) isolation and with plunger cavity (7); When being in the second place, plunger cavity (7) is isolated from return line (12) and common rail (10); When being in primary importance, plunger cavity (7) is connected to common rail (10) from return line (12) isolation and with plunger cavity (7).

12. as any the described fuel injection system in the claim 9 to 11, wherein said NCV (3) isolates described control chamber (17) and open described control chamber (17) and the hydraulic communication between the rail (10) altogether from return line (12) when being in primary importance; When being in the second place, control chamber (17) is connected to return line (12) from common rail (10) isolation and with control chamber (17) hydraulic pressure.

13. as any described fuel injection system in the above-mentioned claim, the device (11) that wherein is used for pressure boosting common rail (10) comprises oil hydraulic pump and device that is used to control described pump delivery of a variable displacement type, so that realizing desirable pressure in the rail altogether.

14. as any the described fuel injection system in the claim 1 to 12, the device that wherein is used for pressure boosting common rail (10) comprises that the oil hydraulic pump of a fixed displacement type and one are used to control the device of the rotational speed of described pump, so that realizing desirable pressure in the rail altogether.

15. fuel injection system as claimed in claim 14, wherein said oil hydraulic pump is driven by the starting motor of motor.

16. as any the described fuel injection system in the above-mentioned claim, the pressure that wherein is total in the rail (10) can be configured to 600 maximum values of clinging to.

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