JP5328802B2 - Fuel injection system for internal combustion engine with HC injector - Google Patents

Description

  In an internal combustion engine that operates in a diesel system, a particulate filter is used more frequently in the exhaust gas path based on exhaust gas regulations that are becoming increasingly strict. Generally, the particulate filter is regenerated by the post-injection of the injector disposed in the combustion chamber by the control device of the internal combustion engine, so that fuel that is not yet burned in the high-temperature exhaust gas is oxidized in the exhaust gas pipe. This provides the heat necessary to regenerate the particulate filter.

  Since post-injection is not sufficient in many cases, it is already known, but a so-called HC (hydrocarbon) injector is provided in the exhaust gas path. The HC injector injects fuel into the exhaust pipe upstream of the single or multiple particulate filters, thereby improving the management of particulate filter regeneration.

  An operating pressure of 7 bar to 10 bar (relative pressure) is desired in order to achieve the finest possible spray of fuel injected by the HC injector. The fuel circuit required for this is relatively expensive based on the injection pressure which is not low and is only occasionally required. Typically, the particulate filter needs to be regenerated every 500 km to 1000 km, which in part corresponds to an operating time greatly exceeding 10 hours, in which case the regeneration takes only about 10 min to 20 min. The HC injector is activated only during this short time. In short, the operating time of the HC injector and the pump arranged upstream is only a small part of the total operating time of the internal combustion engine.

DISCLOSURE OF THE INVENTION An object of the present invention is to provide an improved fuel injection system with HC injectors that is optimized for efficiency and cost.

  According to the apparatus of the present invention for solving this problem, a fuel injection system for an internal combustion engine is provided with a low-pressure part and a high-pressure part, a pre-conveying pump is provided in the low-pressure part, The pump conveys fuel from a fuel tank to a high-pressure pump, and a high-pressure pump is provided in a high-pressure portion. The high-pressure pump conveys fuel under high pressure to a common rail or at least one injection valve. At least one HC injector, wherein the at least one HC injector, when necessary, injects fuel upstream of the one or more particulate filters into the exhaust gas aftertreatment device of the internal combustion engine. To do.

By incorporating the HC injector into the low pressure part of the fuel injection system required in the present invention, a special fuel pump for the HC injector can be omitted. Also, rather than omitting the pump, a pre-conveying pump that is inevitably provided is also used to convey fuel to the HC injector, if necessary. This simplifies the fuel injection system and greatly reduces manufacturing costs. According to a further advantage, no additional fuel pump is required, which reduces the weight of the vehicle with the fuel injection system, and thus fuel consumption and CO ₂ emissions.

  In the form of the fuel injection system according to the invention, the front conveying pump is formed as an electrically driven fuel pump or as a mechanically driven fuel pump. Optionally, an auxiliary fuel pump that can be operatively connected may be provided in addition to the mechanically driven transport pump.

  Auxiliary fuel pumps, which in principle can be connected in an electrically driven manner, are usually used to achieve the fastest possible pressure increase when starting the internal combustion engine. The auxiliary fuel pump may be used to refill the fuel injection system after the tank empty operation. As soon as the internal combustion engine is started and the mechanically driven transport pump creates sufficient pressure, the auxiliary fuel pump is stopped again. According to the present invention, since the auxiliary fuel pump can be operatively connected during operation of the internal combustion engine, a two-stage pressure increase is performed in the low pressure portion of the fuel injection system. The initial pressure increase is exerted by the auxiliary fuel pump, whereas a mechanically driven transport pump located downstream of the auxiliary fuel pump exerts an additional pressure increase. Thus, during the special operation mode, the pressure on the discharge side of the pre-conveying pump is increased as desired in a short time, so that a high pressure sufficient to inject fuel by the HC injector exists in the low pressure portion. Since the auxiliary fuel pump, which can be electrically activated, has a very short operating time, a short additional use of about 10 min to 20 min for regeneration is easily realized and the robustness of the existing auxiliary fuel pump And no additional means are required to increase the service life.

  Optionally, the at least one HC injector can be connected to a fuel inlet or a fuel high pressure pump chamber. Of course, at least one HC injector can also be connected to the return channel.

  In normal operation, it is desired to keep the transport pressure of the pre-transport pump and thus the pressure in the low pressure portion of the fuel injection system as small as possible, so in another advantageous form of the invention the inner chamber and return flow path of the fuel high pressure pump. Between the two, a pressure regulating valve is arranged. The operating pressure of the low-pressure portion of the internal combustion engine during normal operation is adjusted by the pressure adjustment valve. In addition, according to the present invention, the pressure in the low pressure portion of the fuel injection system can be temporarily increased by appropriate control of the pressure regulating valve, which also supplies fuel to the exhaust gas aftertreatment device of the internal combustion engine by the HC injector. The pressure can be increased to provide a sufficiently high pressure to inject.

  The pressure regulating valve can be controlled by, for example, the pressure in the fuel inflow path on the suction side of the front transfer pump. Due to the short-time increase in the conveyance flow rate of the front conveyance pump, the pressure in the low pressure portion also increases according to the characteristic curve of the pressure regulating valve.

  According to another advantageous embodiment of the invention, a switchable throttle is arranged between the pressure regulating valve and the return channel. The switchable throttle can be operated by switching to an electric type or a hydraulic type in order to increase the pressure in the low pressure portion.

  Further, according to the method of the present invention for solving the above-mentioned problem, the fuel injection system is operated, wherein the fuel injection system is provided with the low pressure portion and the high pressure portion, and the pre-transport pump is provided in the low pressure portion. A pre-conveying pump is provided to convey fuel from a fuel tank to a high-pressure pump, and a high-pressure pump is provided in a high-pressure part. The high-pressure pump conveys high-pressure fuel to a common rail or at least one injection valve. And at least one HC injector is connected to the low pressure section, and the at least one HC injector injects fuel into the exhaust pipe of the internal combustion engine upstream of the one or more particulate filters, if necessary. The apparatus is characterized in that the pressure in the low pressure portion of the fuel injection system is increased while the fuel is injected by the HC injector.

  This provides a sufficiently high injection pressure for the HC injector to inject fuel into the exhaust pipe of the internal combustion engine. In the normal operation of the internal combustion engine, that is, in the operation in which the fuel is not injected through the HC injector, the pressure in the low pressure portion of the fuel injection system can be lowered again to the normal value. This particularly reduces the load on the front transport pump, reduces fuel heating, and increases the overall efficiency of the fuel injection system.

  Further, the front transfer pump does not need to be designed to have a continuous operation pressure corresponding to the injection pressure of the HC injector. It is sufficient for the pre-conveying pump to provide the injection pressure of the HC injector for a short time (ie several minutes). As a result, the pre-conveying pump can be made small at low cost.

  The short-time pressure increase in the low-pressure portion required in the present invention is caused by an increase in the control pressure of the pre-conveying pump in the electrically driven pre-conveying pump, or in the pressure-regulated electric driving pump. This can be done by increasing the target value.

  Optionally, in addition to the pre-conveying pump, an electrically driven auxiliary fuel pump can also be provided upstream, so that a temporary pressure increase in the low-pressure part is additional to the pre-conveying pump. This is done by a temporary working connection of the auxiliary fuel pump. This realizes a two-stage pressure increase in the low-pressure portion of the fuel injection system with a simple configuration. In this case, the sum of both pressure increases needs to be large enough to reach the injection pressure of the HC injector. is there.

  As an alternative or in addition, the pressure increase in the low-pressure part can also be effected by the operation of a switchable throttle arranged upstream of the return channel. Due to the desired restriction of the return flow rate, the operating pressure in the low pressure portion changes to a high value according to the characteristic curve of the pressure regulating valve, so that sufficient pressure is achieved to inject fuel by the HC injector.

  The return flow (s), which is the return flow from the pump housing, with or without fuel flowing through the drive shaft support, is passed through a switchable throttle. In this case, the leakage flow rate from the injector can also be passed through a switchable throttle.

  Other advantages and advantageous forms of the invention can be understood from the following description of the drawings, modes for carrying out the invention and claims. The features disclosed in the description of the drawings, the detailed description and the claims are important to the invention, whether individually or in combination.

It is a figure which shows one form of the fuel-injection system by this invention. It is a figure which shows one form of the fuel-injection system by this invention. It is a figure which shows one form of the fuel-injection system by this invention. It is a figure which shows one form of the fuel-injection system by this invention. It is a figure which shows one form of the fuel-injection system by this invention. It is a figure which shows one form of the fuel-injection system by this invention. It is a figure which shows one form of the fuel-injection system by this invention. It is a figure which shows one form of the fuel-injection system by this invention.

BEST MODE FOR CARRYING OUT THE INVENTION FIG. 1 is a block circuit diagram showing a first embodiment of a fuel injection system according to the present invention.

  The fuel injection system mainly includes a fuel high-pressure pump 1, a tank 3, a pressure sensor 4, an electrically driven front transfer pump 5, a fuel filter 7, a rail 9 and a pressure limiting valve 11. The injector connected to the rail 9 is not shown here.

  The pressure limiting valve 11 communicates with the return flow path 13, and a leakage flow rate of an injector (not shown) is also led to the return flow path 13. In this embodiment, the return flow path 13 communicates with the tank 3 and drives the jet pump 10 there.

  A temperature sensor T may be selectively disposed inside the fuel high-pressure pump 1. The fuel high-pressure pump 1 is hydraulically connected to the tank 3 via the fuel inflow passage 15, the filter 7 and the front transfer pump 5. An HC injector 16 is connected to the fuel inflow passage 15 on the downstream side of the front transfer pump 5. The HC injector 16 can inject fuel into an exhaust gas pipe (not shown) of the internal combustion engine, if necessary. The particulate filter is regenerated by injecting the fuel into the exhaust gas pipe as desired upstream of the particulate filter.

  The fuel inflow passage 15 connects the discharge side of the front transfer pump 5 to the inner chamber 17 of the pump housing of the high-pressure pump 1, so that the entire transfer flow of the front transfer pump 5 reaches the inner chamber 17. The connecting channel 18 forms on the one hand a hydraulic connection between the inner chamber 17 of the pump housing and on the other hand between the metering unit 19 and the return channel 13. A pressure regulating valve 20 is disposed between the connection path 18 and the return path 13.

  The metering unit 19 is used to adjust the flow rate of fuel sucked by the pump element 21 of the fuel high-pressure pump 1 and thus the transport flow rate. For this purpose, the suction side of the pump element 21 is connected hydraulically with the outlet of the metering unit 19 via the valve channel 23.

  The pump element 21 mainly comprises a suction valve 25, a high-pressure check valve 27, and a piston 29. The piston 29 reciprocates within a cylinder hole (not labeled). The piston 29 of the pump element 21 is driven by a cam 33 of a drive shaft 35 via a roller tappet 31. The pump element 21 conveys the fuel under high pressure to the rail 9 via the high-pressure channel 34.

  The cam 33 is a part of the drive shaft 35, and the drive shaft 35 can be rotated in a pump housing (not shown) at the first support portion and the second support portion on both sides of the cam 33. It is supported. The drive shaft 35 is disposed in the inner chamber 17 of the pump housing. Through the support portion of the drive shaft 35, a partial flow of fuel that is forced to flow from the fuel inflow path 15 to the inner chamber 17 of the pump housing flows. The support portion is shown as a throttle portion in the block circuit diagram of FIG. The first support portion is denoted by reference numeral 39 in FIG. 1, and the second support portion is denoted by reference numeral 41.

  In the first embodiment of the fuel high-pressure pump according to the present invention shown in FIG. 1, the pressure limiting valve 20 is disposed downstream of the inner chamber 17 of the fuel high-pressure pump 1. The pressure limiting valve 20 includes a control piston 55 and a leakage flow path 57, and the control piston 55 is loaded in the closing direction by a spring 56.

  By disposing the pressure limiting valve 20 on the downstream side of the inner chamber 17, substantially the same pressure as that on the discharge side of the front transport pump 5 acts on the inner chamber 17. Usually, the positive pressure on the discharge side of the front transfer pump 5 and the inner chamber 17 is about 3 bar to 6 bar.

  Due to the pressure acting on the inner chamber 17, in particular, the fuel passing through the support portions 39, 41 receives pressure. Since the first bearing portion 39 and the second bearing portion 41 are formed as sliding bearings in principle, the bearing portions 39 and / or the bearing portion 41 are forced to flow through the bearing portions 39 and 41. A hydrodynamic lubricating wedge is formed. Thereby, the load capability of the 1st support part 39 and the 2nd support part 41 increases significantly, and the heat dissipation from the 1st support part 39 and the 2nd support part 41 is improved simultaneously.

  The arrangement of the pressure regulating valve 20 in the connection path 18 is particularly advantageous in normal operation of the fuel injection system, and can reduce the conveyance output of the front conveyance pump. This means that the normal operating pressure in the low pressure part of the fuel injection system is not sufficient to operate the HC injector. That is, if the pressure at which the fuel is injected into the exhaust gas aftertreatment device of the internal combustion engine by the HC injector 16 is too low, the fuel is not sprayed sufficiently finely, and thus complete combustion of the injected fuel is not guaranteed. Incomplete combustion deteriorates the emission value of the internal combustion engine, which is undesirable.

  According to the present invention, the pressure in the low pressure portion of the fuel injection system can be increased simultaneously with the fuel injection by the HC injector 16. The pressure increase can be performed by increasing the supply voltage of the electrically driven pre-conveying pump 5, so that the pre-conveying pump 5 operates at a high rotational speed, and thus the conveying pressure is increased to a desired value.

Optionally, the operating pressure can also be increased via a pressure regulator. For this purpose, a pressure sensor 4 is required on the transport side of the front transport pump 5, and the pressure sensor 4 is connected to a pressure adjusting device via a signal line (not shown). In the normal operation, the pre-transport pump 5 is set to about 3 bar to 5 bar as the target value p _soll of the pressure in the low pressure portion. When fuel is to be injected by the HC injector, the target value p _soll of the pressure regulator is temporarily increased to a value of about 7 bar to 10 bar. Accordingly, the pre-conveying pump 5 is controlled by the pressure adjusting device so that a desired target pressure p _soll is generated in the low pressure portion.

  Since the regeneration of the particulate filter and the fuel injection to the exhaust gas pipe by the HC injector necessary for this take only 10 to 20 minutes and are rarely required, the front transport pump 5 is damaged during this short operation time. Without operating, or without significantly reducing the service life. The fuel injection system according to the invention can therefore be realized without the introduction of a stronger pump, which is advantageous from an economic point of view.

  In order to avoid that the high pressure formed in the low pressure part due to the HC injection drops again via the support portions 39, 41, the outflow path of at least one of the support portions 39, 41 with the return flow path 13 The flow restriction element 42 can be disposed in the connection path. The outflow passages of both support portions 39 and 41 may be combined first, and then collectively connected to the return flow path 13. In this case, a single flow rate is provided for both support portions 39 and 41. Only the limiting element 42 is required. The flow restriction element 42 can be formed as, for example, a throttle portion. Alternatively, the flow restriction valve 42 may be formed as a throttle that can be switched by a valve configuration that is operated, for example, electrically or hydraulically. Furthermore, the flow restricting element 42 may be formed as a pressure holding valve that opens at a specific pressure and then increases the pressure according to the valve characteristic curve. The combination with the flow restriction element 42 is particularly advantageous when the pressure regulating valve 20 has a progressive spring curve. As a result, in normal operation, that is, operation without HC injection, a constant pressure is obtained as much as possible in the low pressure part. On the other hand, the conveyance amount in the low pressure part increases due to HC injection, and the pressure as strong as possible in the low pressure part. An increase is obtained. The spring of the pressure regulating valve 20 is designed so that the spring strength increases with the opening stroke.

  FIG. 2 shows another embodiment of the fuel injection system according to the present invention. In this embodiment, the front conveyance pump 5 is driven mechanically. In many cases, the pre-conveying pump 5 is directly connected to the drive shaft 35 of the high-pressure pump 1. Due to such a solid connection, when the internal combustion engine is started (of course, the rotational speed is very small here), the pressure rise is performed relatively slowly. In order to make up for the shortage, an auxiliary fuel pump 43 that can be connected in an electrically driven manner is provided upstream of the front transfer pump 5. Since the auxiliary fuel pump 43 is generally operated only when the internal combustion engine is started, a rapid pressure increase is realized in the fuel injection system. According to the present invention, when fuel is to be injected by the HC injector 16, the auxiliary pump is simultaneously operated in series with the front transfer pump 5 in a hydraulic manner even during operation of the internal combustion engine. Therefore, the conveyance output of the auxiliary pump 43 and the front conveyance pump 5 is added to a value sufficient to guarantee the fine spray of fuel by the HC injector.

  A suction throttle 45 is provided on the suction side of the front transport pump, and the suction throttle 45 functions so as to be limited when the transport amount of the front transport pump 5 is a particularly high rotational speed.

  The mechanically driven pre-conveying pump 5 of the second form can be formed as a vane pump, an internal gear pump, in particular, a trochoid pump (Gerotorpump) or an external gear pump. In this pump, a gap exists between the rotating component and the pump housing, and the gap causes leakage loss. In FIG. 2, this gap is represented by a stop (see reference numeral 49). The leakage flow rate flowing out through the gap is led out through the leakage flow path 51. The leakage flow path 51 communicates with a flow path (not labeled) that supplies the flow rate of fuel flowing through the first support portion 39 to the leakage flow path 13.

  In the form shown in FIG. 2, fuel is supplied to the HC injector 16 from the inner chamber 17 of the fuel high-pressure pump 1, and the HC injector 16 is disposed downstream of the front transfer pump 5. The load is applied by the transfer pressure of the front transfer pump 5. When the auxiliary fuel pump 43 is operatively connected (switched on), the pressure in the inner chamber 17 and thus the HC injector 16 increases according to the rotational speed of the high-pressure pump 1 and the output of the auxiliary fuel pump 43.

  FIG. 3 shows another embodiment of the fuel injection system according to the present invention. In this embodiment, the auxiliary fuel pump 43 is not provided, but the pressure rise is performed through a throttle 50 that can be switched electrically, and the throttle 50 is a pressure regulating valve upstream of the return flow path 13. It is arranged behind 20. The fuel flowing through the bearing points 39 and 41 does not flow through the switchable throttle 50.

  In the operating state of the throttle 50, the return flow rate from the inner chamber 17 of the fuel high-pressure pump is reduced. As a result, a pressure rise occurs upstream of the switchable throttle 50, so that the pressure applied to the HC injector 16 is increased to a desired value of 7 bar to 10 bar.

  In the embodiment shown in FIG. 4 of the fuel injection system according to the invention, the switchable throttle 50 is controlled hydraulically. Here, similarly to the embodiment shown in FIG. 3, the return flow path between the pressure regulating valve 20 and the common guide of the return flow rates of the support portions 39 and 41 is narrowed.

  When the control is performed hydraulically, a pressure drop generated at the throttled portion 61 is used. The throttled portion 61 is disposed in the supply path (not labeled) of the HC injector 16. That is, when the HC injector 16 injects fuel, a pressure drop immediately occurs at the throttled portion. The switchable restrictor 50 is hydraulically controlled via a control path in which one is connected to the upstream side of the throttle point and the other is connected to the downstream side of the throttle point 61.

  The throttled portion 61 can be incorporated in the fuel high-pressure pump 1 or the HC injector 16, or can be disposed on the outside in the inflow path of the HC injector 16.

  The return flow rate from the inner chamber 17 of the pump housing can be used for throttling the low pressure part and increasing the pressure. Furthermore, the switchable throttle 50 is returned to the downstream side so that the amount of fuel flowing through the bearings 39 and 41 and / or the leakage flow rate of an injector (not shown) flows through the switchable throttle 50. It can also be arranged on the path 13. In this case, since the return flow rate is high, a high pressure increase can be achieved by operating the switchable throttle 50. Further, the pressure temporarily increased in the return flow path 13a before the throttle 50 causes a high load on the corrugated seal ring included in the support portion 39 and / or the support portion 41.

  In the fuel injection system shown in FIG. 5, since the entire return flow rate flows through the switchable throttle 50, the maximum pressure increase is achieved here.

  In the fuel injection system shown in FIG. 6, a flow control valve 63 is provided. At the illustrated switching position of the flow control valve 63, the fuel inflow passage 15 and the return passage 13 are separated hydraulically. In the second switching position of the flow control valve 63, the return flow path 13 is connected to the fuel inflow path 15. Thereby, the pressure in the fuel return channel exists as a support pressure in the pressure regulating valve 2. Thereby, a temporary pressure increase in the HC injector 16 is achieved.

  In the fuel injection system shown in FIG. 7, a mechanically driven front transfer pump 5 is provided. Here, a switchable throttle 50 is arranged in an inflow path toward the front transfer pump 5. The switchable throttle 50 may be an electrically operated valve as in the embodiment shown in FIG. 3, or may be hydraulically operated as in the embodiment shown in FIG. When the switchable throttle 50 is controlled in a hydraulic manner, a pressure drop that occurs when flowing toward the HC injector 16 is used, as in the embodiment shown in FIG. An auxiliary fuel pump 43 can be provided on the upstream side of the mechanically driven pre-conveying pump 5 as in the embodiment shown in FIG. When a relatively high pressure is required for HC injection in the low pressure part, the switchable throttle 50 is adjusted to a large flow cross section, so that the transport flow rate of the front transport pump 5 is increased, thereby reducing the low pressure. A pressure increase occurs in the part.

  In the fuel injection system shown in FIG. 8, an electrically driven front transfer pump 5 is provided. The return flow path 13 extends from the pressure regulating valve 20 and the inner chamber 17 of the pump housing of the high-pressure pump 1 to the tank 3, and the suction jet pump 10 is connected to the return flow path 13 in the tank. In the return flow path 13, a switchable throttle 50, for example, an electrically operated throttle 50, is disposed upstream of the suction jet pump 10, for example, in the tank 3 or in the suction jet pump 10. When a high proportion of pressure is required for HC injection in the low pressure portion, the switchable throttle 50 is adjusted to a small cross-sectional flow cross section, so that the flow rate of fuel flowing out through the return passage 13 is reduced. This increases the pressure in the low pressure portion.

Claims (17)

A fuel injection system for an internal combustion engine,
A low-pressure part and a high-pressure part are provided, and a pre-conveying pump (5) is provided in the low-pressure part, and the pre-conveying pump (5) supplies fuel from the fuel tank (3) to the high-pressure pump (1). A high-pressure pump (1) is provided in the high-pressure part, and the high-pressure pump (1) has at least one support part (39, 41) disposed in the inner chamber (17) of the high-pressure pump. The inner chamber (17) is a part of the low pressure portion, and the fuel under high pressure is supplied to the common rail (9) or at least one injection valve. In what is transported to
The low-pressure part comprises at least one HC injector (16), which, if necessary, removes fuel from the low-pressure part downstream of the pre-transport pump (5). It is configured to inject into an exhaust gas aftertreatment device of an internal combustion engine ,
At least one HC injector (16) is connected to the fuel inlet (15) or the inner chamber (17) of the high-pressure pump (1),
While the fuel is injected by the HC injector (16), the pressure in the low pressure portion is increased by increasing the inflow flow rate from the pressure in the low pressure portion while the fuel is not injected by the HC injector (16) . A fuel injection system for an internal combustion engine.   The fuel injection system according to claim 1, wherein the front conveying pump is formed as an electrically driven fuel pump.   The fuel injection system according to claim 1, wherein the front conveying pump is formed as a mechanically driven fuel pump. The fuel injection system according to claim 3 , wherein the front conveying pump (5) is formed as a fuel pump that is directly driven by the high-pressure pump (1).   The fuel injection system according to claim 3 or 4, wherein a switchable throttle (50) is provided upstream of the front conveying pump (5).   The fuel injection system according to claim 3 or 4, further comprising an auxiliary fuel pump (43) that can be electrically connected to the mechanically driven pre-conveyance pump (5). During the interior of the high-pressure pump (1) and (17) connected to the return passage to the internal chamber (17) and (13), a pressure regulating valve (20) is arranged, of claims 1-6 The fuel injection system according to any one of the above. 8. The fuel injection system according to claim 7 , wherein a switchable throttle (50) is arranged between the pressure regulating valve (20) and the return channel (13) or in the return channel (13). Switchable diaphragm (50) is switched to an electric or hydraulic, claim 5 or 8 fuel injection system according. Even without least the return flow path (13) connected to said chamber for connection passage between the single bearing (39, 41), through current limiting element (42) is provided, claims 1-9 The fuel injection system according to any one of the above. 11. The fuel according to claim 1, wherein the pre-conveying pump (5) is electrically driven and increases the pressure in the low-pressure part by increasing the control voltage of the pre-conveying pump (5). Injection system. The fuel injection system according to any one of claims 1 to 11, wherein a pressure adjusting device is provided for controlling the pre-conveying pump (5) and increasing the pressure in the low pressure portion to a target value (psoll). In addition to the pre-conveying pump (5), an electrically driven auxiliary fuel pump (43) disposed upstream of the pre-conveying pump (5) is provided to 13. The fuel injection system according to claim 1, wherein the fuel injection system is operated by operating connection of an additional auxiliary fuel pump (43) to the transport pump (5). A method of operating a fuel injection system,
The fuel injection system is provided with a low-pressure part and a high-pressure part, and the low-pressure part is provided with a pre-conveying pump (5), and the pre-conveying pump (5) is connected to the high-pressure pump (1 ), And a high pressure pump (1) is provided in the high pressure portion, and is rotated through at least one support portion (39, 41) disposed in the inner chamber (17) of the high pressure pump. It comprises a drive shaft (35) which is supported in a supported manner, the inner chamber (17) being part of the low pressure part, the high pressure pump (1) delivering fuel under high pressure to the common rail (9) or at least one At least one HC injector (16) is connected to the low pressure section and is transported to one injector, the at least one HC injector (16) supplying fuel, if necessary, of one or more particulate filters. On the upstream side, the internal combustion machine In those injection into the exhaust gas pipe,
At least one HC injector (16) is connected to the fuel inlet (15) or the inner chamber (17) of the high-pressure pump (1),
While fuel is injected by the HC injector (16), the pressure in the low pressure portion is increased by increasing the inflow flow rate from the pressure in the low pressure portion while the fuel is not injected by the HC injector (16) . A method of operating a fuel injection system. 15. The method according to claim 14 , wherein an electrically driven pre-conveying pump (5) is used to increase the pressure in the low-pressure part by increasing the control voltage of the pre-conveying pump (5). The method according to claim 14 or 15 , wherein the pre-conveying pump (5) is controlled by a pressure regulator and the pressure increase in the low pressure part is effected by increasing the pressure target value (psoll). In addition to the pre-conveying pump (5), an electrically driven auxiliary fuel pump (43) disposed upstream of the pre-conveying pump (5) is provided to 17. A method as claimed in any one of claims 14 to 16 , wherein the method is carried out by operative connection of an additional auxiliary fuel pump (43) to the transport pump (5).

Images