JP5727617B2 - Fuel injection system for internal combustion engine - Google Patents

Description

  The present invention relates to a fuel injection system for an internal combustion engine having a tank connected to a pump internal space of a high-pressure pump via a booster pump, and the pump internal space is connected to a pump pressurization chamber via a metering unit. The pump internal space further relates to the fuel injection system, wherein the pump internal space is hydraulically connected to the return pipe via an overflow valve having a valve housing, a valve plunger, and a valve spring disposed in the spring chamber.

  A fuel injection system of this kind for an internal combustion engine is known from DE 102008042089. In the case of this fuel injection system, the connected hydraulic space of the metering unit is connected to the three pump pressurizing chambers of the high-pressure pump via the fuel pipe. The overflow valve of this fuel injection system has a hollow plunger into which a throttle valve is inserted, and this hollow plunger connects the spring chamber of the overflow valve to the inlet side of the overflow valve. With this configuration, the suction pressure at the inlet of the metering unit is corrected and controlled as compared to the prior art, and noise that is squeaky (Quietschgeraeusch) is reliably prevented even when a steel connecting pipe is used.

  Furthermore, it is known that the hydraulic space connected by the metering unit is connected to the tank or the inlet pipe to the pressure boosting pump via a so-called zero pressure throttle valve. Such a zero pressure feed throttle valve eliminates the leakage of the metering unit that may occur when zero pressure feed (Nullfeederung) is set.

  The basis of the present invention is to provide a fuel injection system capable of adjusting the filling pressure of the pump pressurizing chamber according to the pumping amount.

  This problem is solved by connecting the spring chamber to the hydraulic space connected by the measuring unit via the throttle valve circuit. According to the pressure controlled by the metering unit, more or less pressure in the spring chamber of the overflow valve, which is strictly a differential pressure adjusting valve, is adjusted by the throttle valve circuit functioning as a pressure distributor. Accordingly, the pressure before the overflow valve is composed of a purely mechanical component of the valve spring characteristic curve and the hydraulic pressure in the spring chamber. Therefore, since the pressure in the spring chamber can be changed, the pressure before the overflow valve is also changed.

  In a development of the invention, the throttle valve circuit is a line connection with a throttle valve inserted. Since the metering unit and the overflow valve are usually directly integrated into the pump housing of the high-pressure pump, the conduit connection (Leitungsverbundung) can be formed, for example, as a connection channel (Verbindskunkal). In this case, the throttle valve can also be realized by a throttle element built into the connection passage or by a diameter reduction during the manufacturing process of the pipe connection.

  In a development of the invention, the spring chamber is connected to the return pipe, in which, in yet another configuration, a return throttle valve is inserted into the return pipe. At that time, the return pipe can be connected to the pipe connection at an arbitrary position behind the inserted return throttle valve. At that time, the return throttle valve is connected to the downstream side of the connection place. Need to be inserted into the return pipe.

  In yet another configuration of the invention, the throttle valve has a lower throttle rate than the return flow throttle valve. In other words, the flow rate cross section of the throttle valve is larger than the flow rate cross section of the return flow throttle valve. By this adjustment, the pressure in the spring chamber increases when the metering unit is released, and the pressure in the spring chamber gradually drops to almost the return pressure level when the metering unit is closed. Through appropriate adjustment of the diameters of the throttle valve and the return throttle valve, the pressure difference between the open position and the closed position of the metering unit can be adjusted almost arbitrarily.

  In a development of the invention, a filter is connected in front of the throttle valve and / or the return throttle, and this filter can be configured, for example, as a disk filter in the development. Such a filter or disc filter ensures that the throttle valve is protected from contaminating particles.

  In yet another configuration of the invention, the overflow valve drain tube is connected to the return tube. Similarly, in yet another configuration, the bearing lubricant discharge pipe of the high pressure pump is connected to the return pipe. With these configurations, all suitable pipes are already connected to the return pipe in the high-pressure pump, and the return pipe is connected to the tank in an appropriate form via an external pipe connection, so that A compact configuration of the internal fuel injection system is possible.

As described above, the following is achieved by the configuration according to the present invention.
A filling pressure depending on the pumping amount is applied, for example, a high filling pressure is set when the filling demand is high, and a low filling pressure is set when only a small amount of fuel needs to be pumped.
-A clearly expanded work area is realized. That is, the variable pressure level can be set stably. With one overflow valve (with a single adjustment), it is possible to achieve different pressure levels through variations in throttle diameter of the throttle and return throttle valves.
-A small load on the components, especially the valve springs, is realized.
-Cost savings are achieved as a result of avoiding variations and avoiding the use of expensive valve springs, at the same time, the adjustment pressure can be set higher than known solutions.
-A smaller installation space is required. This is because, in the known arrangement, the spring length of the valve spring increases as the adjustment pressure increases, especially when determining the length of sufficient vibration during pressure pulsations.
In the case of the so-called one-actuator system (regulated pressure control only via the metering unit), the throttle valve can additionally function as a zero-feed throttle valve.
-A return throttle can additionally replace the spring chamber / damping valve.

Further advantageous configurations of the invention will become apparent from the description of the drawings. In the description of the drawings, the illustrated embodiment of the invention is described in more detail.
2 illustrates the interaction of basic components of a fuel injection system according to the present invention.

  FIG. 1 schematically shows the interaction of the basic components of a fuel injection system according to the present invention. The booster pump 1 pumps fuel from the tank 2 through the filter device into the pump internal space 3 of the high-pressure pump 5.

  The high-pressure pump 5 has a pump housing, and the pump camshaft is rotatably held in the bearing portions 4a and 4b in the pump housing. The bearing locations 4a and 4b are lubricated by the fuel, and the fuel in the bearing locations 4a and 4b flowing out from the pump internal space 3 through the bearing lubricant discharge pipes 6a and 6b leads to the recirculation pipe 7 leading to the tank 2. It is drained. The pump camshaft translates the pump plunger 8 up and down via a roller tappet during the rotational movement of the pump camshaft. The pump plunger 8 interacts with the pump pressurizing chamber 9, and the pump pressurizing chamber 9 can be connected to the pump internal space 3 via the measuring unit 10. The amount of fuel supplied to the pump pressurizing chamber 9 by the metering unit 10 can be arbitrarily set according to the pressure in the high pressure reservoir, for example. When the pump plunger 8 moves upward, the fuel carried into the pump pressurizing chamber 9 is pumped to the high pressure accumulator via the high pressure oil passage 11. The suction valve necessary for this pressure feed stroke for the fuel carried into the pressurizing chamber 9 is directly inserted into the pump cylinder head 12 of the high pressure pump 5.

  The hydraulic space connected by the metering unit (presented by the connecting pipe 13 to the pump pressurizing chamber 9) is connected directly or indirectly to the spring chamber of the overflow valve 16 via the line connection 14. . The overflow valve 16 has a valve housing 17 in which the valve plunger 18 can be adjusted to resist the force of the valve spring 19. The valve control chamber 20 is connected to the pump internal space 3 (or the supply pipe of the metering unit 10). When the fuel pressure in the pump internal space 3 rises due to the closing of the metering unit 10, the valve plunger 18 is moved in the direction of the spring chamber 15 and connected to the exhaust pipe 21 leading to the return pipe 7. Release the drain hole. For example, when zero pumping is set, the fuel that has been pumped by the booster pump 1 and that is not necessary for lubricating the bearing is drained through the drain pipe 21.

  As described above, the hydraulic space (connection pipe 13) connected by the measuring unit 10 is connected to the spring chamber 15 via the pipe connection 14. At that time, a throttle valve 22 is inserted into the pipe connection 14. Further, the spring chamber 15 is connected to the return pipe 7, and a return throttle valve 23 is inserted into the return pipe 7 in the vicinity of the spring chamber. As shown in the figure, when the pipe connection 14 is connected to the spring chamber 15 via the return pipe 7, the return throttle valve 23 is disposed downstream of the connection location in any case. . The throttle diameter of the throttle valve 22 is larger than the throttle diameter of the return throttle valve 23. Therefore, when the metering unit 10 is released, the pressure in the spring chamber 15 increases and the metering unit 10 is closed. In this case, the pressure in the spring chamber 15 is continuously reduced to the pressure in the return pipe 7.

A filter, particularly a disk filter, may be connected in front of the throttle valve 22 and the return flow throttle valve 23.

Claims (10)

A fuel injection system for an internal combustion engine comprising a tank (2) connected to a pump internal space (3) of a high-pressure pump (5) via a booster pump (1), wherein the pump internal space (3) Is connected to the pump pressurization chamber (9) via the metering unit (10), and the pump internal space (3) further includes a valve housing (17), a valve plunger (18), and a spring chamber (15). In the fuel injection system, the spring chamber (15) is a throttle valve, hydraulically connected to the return pipe (7) via an overflow valve (16) having a valve spring (19) disposed therein. The fuel injection system is connected to a hydraulic space connected downstream of the metering unit (10) via a circuit.   2. The fuel injection system according to claim 1, wherein the throttle valve circuit is a pipeline connection (14) into which a throttle valve (22) is inserted.   The fuel injection system according to any one of claims 1 to 2, wherein the spring chamber (15) is connected to the return pipe (7).   The fuel injection system according to claim 3, characterized in that a return throttle valve (23) is inserted into the return pipe (7).   The fuel injection system according to claim 4, characterized in that the throttle valve (22) has a lower throttle rate than the return flow throttle valve (23). 6. The fuel injection system according to claim 4 , wherein a filter is connected in front of the throttle valve (22) and / or the return throttle valve (23).   The fuel injection system according to claim 6, wherein the filter is a disk filter.   The fuel injection system according to any one of claims 1 to 7, wherein an exhaust pipe (21) of the overflow valve (16) is connected to the return pipe (7).   The bearing lubricant drain pipe (6a, 6b) of the high-pressure pump (5) is connected to the return pipe (7), according to any one of claims 1-8. Fuel injection system.   10. The fuel injection system according to claim 1, wherein the return pipe (7) communicates with the tank (2).

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