Fuel delivery device for a fuel injection system

Abstract

Fuel delivery device for a fuel injection system, in particular a common rail injection system, comprising an electric fuel pump as a pre-feed pump (2), by means of which fuel can be sucked in from a fuel tank (1) and fed via a low-pressure line (3) to an inlet region (4) of a high-pressure pump (5), further comprising a pressure sensor (6, 6'), characterized in that the pre-feed pump (2) is designed as a controlled electric fuel pump and a measured value detected by means of the pressure sensor (6, 6') serves as the controlled variable for controlling the pre-feed pump (2), wherein the pressure sensor (6, 6') is integrated into the high-pressure pump (5).

Description

[0001] The invention relates to a fuel delivery device for a fuel injection system, in particular a common rail injection system, having the features of the preamble of claim 1. State of the art

[0002] A fuel injection system with a fuel delivery device of the aforementioned type is disclosed, for example, in published patent application DE 101 46 474 A1. It comprises a fuel reservoir, an electric fuel pump as a pre-feed pump for delivering fuel from the fuel reservoir to a low-pressure region, and a high-pressure pump for delivering the fuel from the low-pressure region to a high-pressure region. A pressure damper is arranged in the low-pressure region; its task is to dampen pressure pulsations occurring in the low-pressure region in order to reduce the load on the low-pressure region. Furthermore, a diagnostic device is assigned to the low-pressure region to monitor the functionality of the pressure damper. The diagnostic device is designed to determine and evaluate the pressure curve in the low-pressure region and to use the determined pressure curve as a diagnostic value.To record the pressure curve, a pressure sensor is provided in the low-pressure area.

[0003] The document DE 10 2011 082 704 A1 discloses a high-pressure fuel pump for an injection system of an internal combustion engine with a pump housing and a pump piston guided in a pump cylinder and movable up and down in translation, wherein a temperature sensor is provided for determining a temperature of a medium, in particular fuel, delivered by the high-pressure fuel pump.

[0004] The document DE 10 2010 043 283 A1 discloses a low-pressure circuit for a fuel injection system, in particular a common rail injection system, comprising a fuel tank and a pre-feed pump, by means of which fuel can be sucked from the fuel tank and fed via a fuel line to a low-pressure region of a high-pressure pump, wherein a metering unit for quantity regulation is arranged in the low-pressure region.

[0005] The document DE 10 2010 064 374 B3 discloses a fuel injection system of an internal combustion engine, a pressure control method of a fuel injection system, a control unit of a motor vehicle and a motor vehicle, wherein a fuel pressure sensor for monitoring a fuel pressure in the high-pressure fuel reservoir is arranged on a high-pressure fuel reservoir.

[0006] Based on the above-mentioned prior art, the present invention is based on the object of providing a fuel delivery device for a fuel injection system which is simpler in design and more cost-effective to manufacture.

[0007] The object is achieved by a fuel delivery device having the features of claim 1. Advantageous developments of the invention are specified in the subclaims. Disclosure of the invention

[0008] The proposed fuel delivery device for a fuel injection system, in particular a common rail injection system, comprises an electric fuel pump as a pre-feed pump, by means of which fuel can be sucked in from a fuel storage tank and fed to an inlet area of ​​a high-pressure pump via a low-pressure line. The fuel delivery device further comprises a pressure sensor. According to the invention, the pre-feed pump is designed as a controlled electric fuel pump and a measured value detected by the pressure sensor serves as the controlled variable for controlling the pre-feed pump, wherein the pressure sensor is integrated into the high-pressure pump. The integration of the pressure sensor in the high-pressure pump has the advantage that an additional carrier for accommodating the sensor is no longer required. This makes it possible to simplify the fuel delivery device. This also has a positive effect on manufacturing costs. Furthermore, the measured value detected by the pressure sensor, i.e.i.e. the measured pressure, can be used as a control variable to regulate the electric fuel pump so that it can be regulated according to requirements.

[0009] According to a preferred embodiment of the invention, the pressure sensor is arranged in the region of an inlet bore of the high-pressure pump. In this way, the pressure in the inlet bore of the high-pressure pump can be detected. A drive chamber of the high-pressure pump is supplied with a quantity of lubricant and / or cooling via the inlet bore. The pressure in the inlet bore of the high-pressure pump therefore provides information about the quantity of lubricant and / or cooling available to the high-pressure pump. If the quantity of lubricant and / or cooling is insufficient, the pressure drops below a definable limit. If this is the case, the delivery rate of the pre-feed pump must be increased in order to provide the high-pressure pump with additional lubricant and / or cooling to prevent damage to the system.

[0010] Alternatively or additionally, a pressure sensor can also be arranged in the area of ​​a drive chamber of the high-pressure pump. In this way, the pressure in the drive chamber of the high-pressure pump can be measured. The drive chamber of the high-pressure pump accommodates the drive shaft of the high-pressure pump, which is rotatably mounted in bearing bores of the pump housing. The bearing bores or shaft bearings, for example, are supplied with a quantity of lubrication and / or cooling via the drive chamber. The pressure prevailing in the drive chamber therefore provides information about the quantity of lubrication and / or cooling present there, or about any insufficient lubrication and / or cooling of the high-pressure pump.

[0011] Advantageously, a pressure side of the pre-feed pump can be connected to a suction side of the pre-feed pump via an overflow valve or a throttle. This prevents overpressure in the low-pressure line, which could be caused, for example, by a contaminated downstream fuel filter. The pre-feed pump is then controlled according to the measured values ​​(pressure) against the overflow valve or throttle.

[0012] Furthermore, it is proposed that the high-pressure pump be connected to the fuel tank via a return line. The used lubricant and / or cooling fluid can then be returned to the fuel tank via the return line. Preferably, the bearing bores formed in the pump housing for rotatably supporting the drive shaft are connected to the return line. As a result, the drive chamber is indirectly connected to the return line via the bearing bores. Furthermore, the drive chamber of the high-pressure pump can be directly connected to the return line.

[0013] Furthermore, the pressure sensor is preferably inserted into a bore in a housing part of the high-pressure pump. Such a bore can be produced easily and cost-effectively. Preferably, the pressure sensor is screwed into the bore in the housing part of the high-pressure pump. The screw connection simplifies the replacement of the sensor, should it become necessary.

[0014] For example, a high-pressure pump can also be designed with an integrated pressure sensor for detecting the pressure in the inlet area of ​​the high-pressure pump. The detected pressure serves as a controlled variable for a pre-feed pump designed as a regulated electric fuel pump. The inlet area of ​​the high-pressure pump comprises an inlet bore, via which an engine compartment of the high-pressure pump can be supplied with a quantity of lubrication and / or cooling, as well as the engine compartment itself. The sensor(s) can therefore be arranged in the inlet bore and / or in the engine compartment. The measured values ​​detected by the sensor(s) provide information about the quantity of lubrication and / or cooling present in the inlet area of ​​the high-pressure pump or about any insufficient lubrication and / or cooling of the high-pressure pump. If the latter is the case, a larger quantity can be requested via appropriate control of the pre-feed pump.The high-pressure pump can, for example, be connected to a low-pressure circuit.

[0015] Preferred embodiments of the invention are explained in more detail below with reference to the single accompanying drawing. This shows a schematic representation of a fuel delivery device according to the invention. Detailed description of the drawing

[0016] The fuel delivery device for a fuel injection system shown in the figure comprises a fuel tank 1 with an electric fuel pump used therein as the pre-feed pump 2. Fuel is sucked in from the fuel tank 1 via the pre-feed pump 2 and fed to the inlet area 4 of a high-pressure pump 5. For this purpose, the pre-feed pump 2 is connected to the inlet area 4 of the high-pressure pump 5 via a low-pressure line 3. A fuel filter 15 is arranged in the low-pressure line 3 to remove dirt particles contained in the fuel. The filter 15 can become clogged, so that the pressure in the low-pressure line 3 upstream of the filter 15 rises. To prevent a predeterminable limit pressure in the low-pressure line 3 from being exceeded, a pressure side 9 of the pre-feed pump 2 can be connected to a suction side 11 of the pre-feed pump 2 via an overflow valve 10.If the opening pressure of the overflow valve 10 is exceeded, it opens and the low-pressure line 3 is relieved.

[0017] As can also be seen from the figure, the inlet area 4 of the high-pressure pump 5 comprises an inlet bore 7 and an engine chamber 8. The engine chamber 8 of the high-pressure pump 5 is supplied with fuel via the inlet bore 7. At least a portion of the fuel quantity entering the engine chamber 8 serves as a lubricating and / or cooling quantity, which in particular serves to lubricate and / or cool shaft bearings 17 of a drive shaft 18 accommodated in the engine chamber 8. The shaft bearings 17 are connected to a return line 12, which connects the engine chamber 8 to the fuel storage tank 1. The lubricating and / or cooling quantity flowing out via the shaft bearings 17 can thus be guided back into the fuel storage tank 1 via the return line 12.The return line 12 connected to the engine compartment 8 has a throttle 19, so that when the high-pressure pump 5 is not delivering any flow, a constant outflow via the throttle 19 is ensured, thus ensuring minimum lubrication and / or cooling. A damping device 16 is also provided downstream of the throttle 19.

[0018] The illustrated high-pressure pump 5 has at least one pressure sensor 6, 6' in the inlet area 4, via which the pressure in the inlet area 4 of the high-pressure pump 5 can be detected. The detected measured values ​​(pressure) provide information about the amount of lubrication and / or cooling present in the inlet area 4 of the high-pressure pump 5 and can thus be used as a controlled variable for controlling the pre-feed pump 2 in order to ensure a sufficient amount of lubrication and / or cooling in the inlet area 4 of the high-pressure pump 5.

[0019] As shown in the figure, the pressure sensor 6, 6' can be arranged in the region of the engine compartment 8. For example, a housing part 14 of the high-pressure pump 5 can be provided with a bore 13 that extends to the engine compartment 8 and accommodates the pressure sensor 6. The same illustration shows an alternative arrangement of the pressure sensor 6, 6'. According to this arrangement, a pressure sensor 6' is arranged in the inlet bore 7.

[0020] By using the measured values ​​recorded via the pressure sensor 6, 6' to control the pre-feed pump 2, the high-pressure pump 5 can always be provided with a sufficient amount of lubrication and / or cooling.

Claims

[1] Fuel delivery device for a fuel injection system, in particular a common rail injection system, comprising an electric fuel pump as a pre-feed pump (2), by means of which fuel can be sucked from a fuel tank (1) and fed via a low-pressure line (3) to an inlet area (4) of a high-pressure pump (5), further comprising a pressure sensor (6, 6'), characterized by that the pre-feed pump (2) is designed as a controlled electric fuel pump and a measured value detected by means of the pressure sensor (6, 6') serves as the controlled variable for controlling the pre-feed pump (2), wherein the pressure sensor (6, 6') is integrated into the high-pressure pump (5). [2] Fuel delivery device according to claim 1, characterized by that the pressure sensor (6') is arranged in the region of an inlet bore (7) of the high-pressure pump (5), so that the pressure in the inlet bore (7) of the high-pressure pump (5) can be detected. [3] Fuel delivery device according to claim 1, characterized by that the pressure sensor (6) is arranged in the region of an engine chamber (8) of the high-pressure pump (5), so that the pressure in the engine chamber (8) of the high-pressure pump (5) can be detected. [4] Fuel delivery device according to one of the preceding claims, characterized by that a pressure side (9) of the pre-feed pump (2) can be connected to a suction side (11) of the pre-feed pump (2) via an overflow valve (10) or a throttle. [5] Fuel delivery device according to one of the preceding claims, characterized by that the high-pressure pump (5) is connected to the fuel tank (1) via a return line (12). [6] Fuel delivery device according to one of claims 3 to 5, characterized by that the pressure sensor (6') is inserted, preferably screwed, into a bore (13) of a housing part (14) of the high-pressure pump (5).

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