DE102007030224A1 - Fuel pump, particularly for fuel system of internal combustion engine, has two valve units, which are coupled with each other that movement of former valve unit in opening direction produces closing movement of latter valve unit - Google Patents

Abstract

The fuel pump has a valve unit (23), which is arranged between a high pressure area (45) and a low pressure area (22) of the fuel pump (5). Another valve unit (25) is arranged in flow direction outside an inlet of a pump device (46) for transporting fuel from the low pressure area in the high pressure area. The two valve units are coupled with each other that a movement of the former valve unit in opening direction produces a closing movement of the latter valve unit.

Description

State of the art

The The invention relates to a fuel pump, in particular for a fuel system of an internal combustion engine, with a first Valve device between a high pressure area and a Low pressure region of the fuel pump is arranged, and a second valve device, which in the flow direction an inlet of a pumping device for fuel delivery is arranged from the low pressure area in the high pressure area.

From the DE 10 2004 048 594 A1 a fuel system for an internal combustion engine is known, which has such a fuel pump, which in particular for improving the reliability of the fuel system comprises two valve devices having a common electromagnetic actuator.

Disclosure of the invention

task The invention is a fuel pump, in particular for to provide a fuel system of an internal combustion engine their operation a pressure prevailing in the high pressure area as possible has constant value and in particular is limited to the top, and yet easy and inexpensive to produce.

These Task is achieved by a fuel pump with the features of the claim 1 solved. Features important to the invention Further, from the following description and the drawing the characteristics being important alone or in different combinations can be without explicit reference.

at the realization of the fuel pump according to the invention needs no particular for the second valve device provided electromagnetic actuator be because the second valve means of the first valve means is pressed. The first valve device is further preferably hydraulically actuated (for example, if It is designed as a simple pressure relief valve), so that the whole device completely without an electrical actuator can be realized. So it can be a "self-regulation" with integrated Pressure limiting function are created.

Thereby that in existing fuel pumps existing electromagnetic Actuator, usually a Magnetic coil and a magnet armature includes, eliminates, builds the Fuel pump particularly small and inexpensive. Further can be dispensed with a complex control. Thus, in the realization of the invention, not only the fuel pump itself be improved, but beyond that in the motor vehicle existing control or regulation facilities or corresponding tax or simplified control procedures, resulting in further cost savings leads. Finally, a well-known for the operation Fuel pumps required pressure sensor in the high pressure range dispensable.

in this connection It is particularly preferred that the first valve device and the second valve device are coordinated with each other so that the first valve means completely closed and the second Valve device is fully open when a Pressure in the high pressure range is less than a minimum pressure. at low pressure in the high pressure area, for example, during startup the fuel pump occurs is the per unit time of the low pressure area amount of fuel delivered in the high pressure area (delivery rate) especially due to this position of the two valve devices high, so that in the high pressure area quickly one for the operation an engine sufficiently high pressure builds up.

It is further preferred that the first valve means and the second Valve device are coordinated so that at a Pressure in the high pressure area above the minimum pressure an opening degree the lower the second valve device, the higher the higher the pressure in the high pressure area is. This will be easy provided a continuous regulation of the pressure in the high pressure area. Because at a low pressure, the fuel pump promotes due the relatively wide open second valve means a large amount of fuel per unit of time in the high pressure area, so that the pressure in the high pressure area increases. As with increasing Pressure the second valve device is gradually closed, the delivery rate of the fuel pump is gradually reduced. If a certain maximum pressure in the high pressure range is reached, then completely closes the second valve device, so that the delivery rate is at least approximately zero reached. During operation of an internal combustion engine, the high pressure area the fuel pump a certain amount of fuel per unit time taken (about for injection into combustion chambers of the internal combustion engine), so ideally opens the opening degree of the second Valve device so that the delivery rate of the fuel pump just the amount of fuel taken from the high pressure area per unit time equivalent. The pressure in the high pressure range remains at least approximately constant.

Furthermore, it is preferred that the first valve device and the second valve device aufeinan so are tuned that when reaching or exceeding a maximum pressure in the high pressure region, the first valve means open and the second valve means is closed. In this way, a pressure limiting function is provided, which avoids an increase in the pressure in the high pressure region to a value which is well above the maximum pressure. This pressure limiting function works particularly reliable, since it comprises two parallel measures: not only is closed by the closing of the second valve means, the delivery rate of the fuel pump greatly or completely prevented the promotion of the fuel pump, but by the opening of the first valve means is also a return flow of the fuel from High pressure range brought into the low pressure range.

It can be provided that between the high pressure area and the first valve means a throttle is arranged. This can be annoying Effects of pressure pulsations in the high-pressure range on the control behavior the fuel pump be reduced.

Furthermore it can be provided that the first and the second valve device are arranged in a common cylinder-like housing. An assembly comprising the two valve devices, which also referred to as "metering unit" can be particularly simple, inexpensive and be realized compact. Also, such is a simple coupling the two valve devices possible because the two valve devices can be arranged close to each other.

in this connection can be provided that the first valve means as a Slide valve with a housing bush and a bolt-shaped Valve element is formed, wherein the housing bush in the common housing firmly held, preferably pressed is. In this way, the first valve device can be very compact and with a small number of parts.

Of Furthermore, it can be provided that the housing bushing has a mounting collar, the axial of the bolt-shaped Valve element is located away. The mounting collar does not hold only the housing socket in the cylinder-like housing fixed, but also closes the entire metering unit High pressure side down. Due to the axial distance remains during the pressing the leadership of the valve element unaffected.

It is also preferred that the bolt-shaped Valve element at one end of the pressure in the high pressure area and on other end of a valve element of the second valve device is charged. This allows on the one hand a simple operation the valve element of the first valve device in dependence from the pressure prevailing in the high pressure area. On the other hand, it will in a particularly simple manner, the coupling according to the invention the two valve devices causes, because a movement of the bolt-shaped Valve element of the first valve device leads directly to a corresponding movement of the valve element of the second valve device. The opening direction of the first valve device corresponds preferably the closing direction of the second valve device, because thereby the above-described type of coupling of the two Valve device is particularly easy to accomplish, for example by a linear arrangement.

It can be provided that between the high pressure area and the first valve means arranged throttle through a constriction is formed in the inlet region of the housing socket. Thereby The throttle can be integrated into the metering unit with little effort and thus be realized in a space-saving manner.

Further It is preferred that the second valve device as a slide valve formed with a spring-loaded piston-like valve element is. Such works reliably and can be cost-effective will be realized. The spring is preferably selected that the second valve device falls below the minimum pressure is fully open in the high pressure area. It can be provided that the spring has a low spring stiffness has, so that the pressure prevailing in the high pressure area as possible regardless of the current flow rate, ie the opening degree of the second valve means, the fuel pump is. By choosing the spring preload and / or the pressure surface the valve element of the first valve device may be a desired Pressure in the high pressure range can be adjusted.

The piston-like valve element of the second valve device and the bolt-shaped valve element of the first valve device can be integrally connected. In this way, the number of parts of the fuel pump can be further reduced making the fuel pump even easier and less expensive can be produced.

It can be provided that the cylinder-like housing has a collar and / or a sealing element for connection to a housing of the fuel pump. This facilitates integration into the housing of the fuel pump, which ultimately saves costs and provides a compact overall unit. Since the metering unit is integrated with the fuel pump, all the sealing points between the metering unit and the remainder of the fuel pump are inside the fuel pump. In the event of leaks, no fuel can escape from the fuel pump.

Brief description of the drawings

following will be an exemplary embodiment of the present Invention with reference to the accompanying drawings closer explained. Like elements bear the same reference numerals and are usually described only once in detail. In the Drawing show in a schematic representation:

1 a fuel system and an internal combustion engine;

2 a longitudinal section of a metering unit according to the preferred embodiment of the present invention with an open second valve device;

3 a representation similar 2 but with partially closed second valve means;

4 a representation similar 2 but with the second valve device closed;

5 a representation similar 2 but with the second valve device closed and the first valve device open;

6 a sectional plan view of a fuel pump according to the preferred embodiment of the present invention;

7 a longitudinal section of the fuel pump 6 along the section line VII-VII; and

8th a longitudinal section of the fuel pump 6 along the section line VIII-VIII.

Embodiments of the invention

This in 1 shown fuel system 1 has a fuel tank 3 , a high-pressure fuel pump 5 and a high-pressure accumulator 7 ("Rail"), at the injection valves 9 are connected to. The injectors 9 are on an internal combustion engine 11 arranged and inject fuel into the combustion chambers (not shown). The fuel tank 3 is via a pre-feed pump 13 and one downstream of the prefeed pump 13 arranged fuel line 15 with the high pressure fuel pump 5 connected. In the fuel line 15 is a filter 17 , then a pressure damper 19 and further a metering unit 21 arranged. Fuel tank 3 , Pre-feed pump 13 , Fuel line 15 , Filters 17 and pressure damper 19 belong to a low pressure area 22 ,

The metering unit 21 is in the high pressure fuel pump 5 integrated and has a first valve device 23 and a second valve device 25 with a valve spring 27 on. The valve spring 27 exercises on the second valve device 25 a force acting in its opening direction. The two valve devices 23 . 25 are so via a mechanical coupling device 29 coupled together, that a movement of the first valve means 23 in the opening direction, a closing movement of the second valve device 25 causes. The second valve device 25 is downstream with the fuel line 15 connected and upstream via an inlet valve designed as a check valve 31 with a workroom 33 a pump cylinder 35 the high pressure fuel pump 5 connected.

One in the pump cylinder 35 slidably mounted pump piston 37 is from a camshaft 39 during a rotary movement (arrow 41 ), in turn, from the internal combustion engine 11 is driven - for example, by a cam or crankshaft of the internal combustion engine 11 , Cam of the camshaft 39 can also be part of the cam or crankshaft of the internal combustion engine 11 be.

The workroom 33 the fuel pump 5 is via a likewise designed as a check valve exhaust valve 43 with a high pressure area 45 connectable. The workroom 33 , the pump cylinder 35 and the pump piston 37 are part of a pumping device 46 , To the high pressure area 45 include in particular the high-pressure accumulator 7 , a connection line 47 coming from the exhaust valve 43 to the first valve device 23 leads, and a high pressure line 49 going to the high pressure store 7 leads. The first valve device 23 has a hydraulic actuating mechanism 50 on, which causes the first valve means 23 with increasing pressure in the high pressure area 45 increasingly opens (the hydraulic actuating mechanism 50 acts on the second valve device 25 ie in the closing direction).

The first valve device 23 when open, connects the high pressure area 45 with the low pressure area 22 , The second valve device 25 when open, connects the low pressure area 22 with the inlet valve 31 the high pressure pump 5 ,

At his the cam 39 facing side, the pump cylinder 35 a cylinder sealing element 51 for sealing the gap (without reference numeral) between the pump piston 37 and pump cylinders 35 on. Furthermore, between the pump cylinder 35 and the fuel line 15 a return line 53 to return one over the cylin derdichtelement 51 flowing fuel quantity in the low pressure range 22 available.

When operating the fuel system 1 pumps the prefeed pump 13 Fuel from the fuel tank 3 through the fuel line 15 and the filter 17 to the metering unit 21 the fuel pump 5 and acts on the fuel with a relatively low feed pressure. This dampens the pressure damper 19 from the pumping device 46 generated pulsations. Furthermore, the pressure damper ensures 19 a high degree of delivery of the fuel pump 5 even with high turning and cam numbers. The second valve device 25 regulates the low pressure side, the flow rate of the fuel pump 5 , This is the second valve device 25 with the valve spring 27 biased in the opening direction, and due to the mechanical coupling device 29 becomes the first valve device 23 through the valve spring 27 "indirectly" acted upon in the closing direction. Is the high-pressure accumulator 7 depressurized, is the second valve device 25 So open and the first valve device 23 closed.

If the pressure in the high pressure area increases 45 , moves in 1 not shown valve element of the first valve device 23 in the opening direction, but still without the high pressure area 45 with the fuel line 15 to connect, and due to the coupling by means of the coupling device 29 closes the second valve device 25 against the force of the valve spring 27 , Promotes the fuel pump 5 So too much fuel per unit time, then the pressure in the high pressure area 45 and the second valve device 25 closes something and reduces the delivery rate. Promotes the fuel pump 5 but too little, then the pressure drops in the high pressure area 45 , and the second valve device 25 opens, leaving more fuel in the high-pressure accumulator 7 is encouraged. In this way, a regulation of the delivery rate of the fuel pump 5 carried out.

After the "metering" of the workspace 33 to conductive amount of fuel through the metering unit 21 the fuel passes through the intake valve 31 in the workroom 33 the fuel pump 5 , The volume of the work space 33 depends on the position of the pump piston 37 in the pump cylinder 35 from. During the downward movement of the pump piston 37 (referring to the schematic representation in FIG 1 ) becomes the workspace 33 increases, whereby fuel is sucked in (suction stroke of the pump piston 37 ). During the upward movement of the pump piston 37 , the fuel is subjected to a high pressure and the exhaust valve 43 in the high pressure line 49 and further into the high-pressure accumulator 7 conveyed (delivery stroke of the pump piston 37 ).

In a normal operation of the fuel system 1 That is, when a maximum pressure in the high pressure area 45 is not reached or exceeded, the first valve device remains 23 the metering unit 21 in a closed position. Only when reaching or exceeding the maximum pressure opens the first valve device 23 so that fuel is from the high pressure area 45 in the low pressure area 22 outflow and a pressure limiting function can be realized.

The 2 to 5 show the metering unit 21 in various work areas (full funding, partial funding, production stop, pressure limitation) and more in detail. The metering unit 21 has a cylinder-like housing 61 on. On an outside 65 of the housing 61 are each an annular sealing element 67 and a ring-shaped collar 69 arranged. With the help of the federal government 69 can the metering unit 21 firmly with a housing of the fuel pump 5 be connected, as will be shown below. The sealing element 67 serves to seal between the high pressure area 45 and an area (not numbered) between the second valve means 25 and the inlet valve 31 ,

The first valve device 23 and the second valve device 25 are almost entirely inside the case 61 arranged, wherein a part of the second valve means 25 namely, a penholder 71 , but something from the case 61 protrudes. The penholder 71 is fixed to the case 61 connected, and on him the valve spring is supported 27 from. He points to his from the case 61 side facing away from a flow cross-section 75 forming opening, which hydraulically with the fuel line 15 , ie the low pressure area 22 connected is.

In the case 61 is along a longitudinal axis 72 of the housing 61 a piston-like valve element in the form of a valve spool 73 available. The valve spool 73 has control cross sections 77 in the form of radial openings. The housing 61 points to an inside 79 a circumferential groove 81 on, which open with the second valve device 25 with the control cross sections 77 overlaps. The groove 81 is with radial outflow holes 83 which in turn is hydraulically connected to the inlet valve 31 the fuel pump 5 are connected. At his from the pen 71 remote and "closed" front side, the valve spool 73 Pressure relief openings 85 on.

The first valve device 23 has a housing socket 87 on, over a mounting collar 88 firmly with the housing 61 connected, for example, is pressed. At her from the valve spool 73 facing away from the housing socket 87 an inlet opening 89 on which hydraulically with the high pressure area 45 connected is. Further includes the housing socket 87 in its peripheral wall (without reference numeral) Absteuerquerschnitte 91 , which hydraulically via the pressure equalization holes 85 and the flow area 75 with the low pressure area 22 are connected. In the housing socket 87 is a bolt-shaped valve element 93 in the direction of the longitudinal axis 72 of the housing 61 slidably mounted.

In the in the 2 to 5 shown embodiment are each two control cross sections 77 , two outflow holes 83 , two pressure equalization holes 85 as well as two Absteuerquerschnitte 91 available. Notwithstanding this, in another embodiment, a different number of each of these elements 77 . 83 . 85 . 91 be provided. The numbers of these elements need 77 . 83 . 85 . 91 not to be identical.

The first valve device 23 is open when the bolt 93 in the presentation of the 2 to 5 shifted so far to the right that he the Absteuerquerschnitte 91 no longer covered while the second valve means 25 is closed when the valve spool in the illustration of the 2 to 5 shifted so far to the right that the control cross sections 77 no longer with the groove 81 overlap. The two valve devices 23 . 25 are coupled by the valve spring 27 the valve spool 73 at the bolt 93 pushes and a movement of the bolt 93 in the opening direction of the first valve device 23 to a movement of the valve spool 73 in the closing direction of the second valve device 25 leads. The opening direction of the first valve device 23 So corresponds to the closing direction of the second valve device 25 ,

The inlet opening 89 is in a mission 96 formed and over a bottleneck, which is a choke 95 forms, with an interior (without reference numeral) of the housing socket 87 connected. The throttle 95 serves to reduce the disturbing effects of undesired pressure pulsations of the fuel pump 5 on the control behavior of the metering unit 21 , The use 96 limits the stroke of the bolt 93 in the closing direction of the first valve device 23 ,

In 2 shows the metering unit 21 at full delivery: the Absteuerquerschnitt 91 is through the bolt 93 covered, whereby the first valve device 23 closed is. At the same time, the groove overlaps 81 completely with the control cross section 77 of the valve spool 73 , so that fuel from the flow cross sections 75 to the discharge holes 83 can reach (the second valve means 25 is thus completely open). This position of the metering unit 21 then occurs when the pressure in the high pressure area 45 falls below a minimum pressure.

3 shows the metering unit 21 in a designated as partial funding operating condition. The in the high pressure area 45 existing pressure acts on one of the inlet opening 89 facing pressure surface 97 of the bolt 93 , This creates a compressive force that ultimately counteracts the spring force of the valve spring 27 works and the bolt 93 the first valve device 23 together with the adjoining valve spool 73 the second valve device 25 in 3 moved to the right. The control cross section 77 of the valve spool 73 is now partially from the housing 61 covered, the free flow area thereby reduced, whereby the fuel flow to the pumping device 46 , that is the fuel flow from the flow area 75 to the outlet hole 83 , throttled and thus the delivery rate of the fuel pump 5 is reduced. The first valve device 23 but is still closed. If the pressure falls in the high pressure area 45 , so relaxes the valve spring 27 again, causing the valve spool 73 against the opening direction of the first valve device 23 and thus in the opening direction of the second valve device 25 (in 3 moved to the left), so that the control cross-section 77 less of the case 61 is covered and the delivery rate of the fuel pump 5 raised again. Thus, depending on the pressure in the high pressure area 45 a Mengenzumessung carried out. A desired pressure in the high pressure area 45 can by suitable choice of the spring preload of the valve spring 27 and / or the printing surface 97 of the bolt 93 be set. So the pressure in the high pressure area 45 as constant as possible above the flow rate of the fuel pump 5 is, is the valve spring 27 designed so that their spring stiffness is relatively low.

4 shows the metering unit 21 in the closed position of the second valve device (delivery stop). The pressure in the high pressure area 45 is so high and the bolt 93 together with the valve spool 73 against the force of the valve spring 27 so far in 4 shifted to the right that the control cross section 77 from the case 61 is completely covered, so no fuel through the outlet hole 83 can flow, wherein the first valve means 23 still closed. The pressure in the high pressure area 45 So has reached or exceeded a delivery stop pressure.

5 shows the metering unit in the operating range of the pressure relief: The pressure in the high pressure range 45 has reached or exceeded a maximum pressure. At this pressure, the bolt has against the force of the valve spring 27 in 5 so far moved to the right that he now the Absteuerquerschnitt 91 partially releases, leaving fuel from the high pressure area 45 via a Absteuerspalt 99 , the Absteuerquerschnitt 91 , the pressure equalization holes 85 and the flow area 75 to the Low pressure area 22 can flow out. During this state of high pressure shutdown is the control cross section 77 completely from the housing 61 covered, so that ideally no fuel through the second valve means 25 to the fuel pump 5 arrives.

The embodiment shown is thus designed so that the delivery stop pressure is less than the maximum pressure. The difference between the maximum pressure and the delivery stop pressure results in the pressure range in which the metering unit is located 21 is in the state of conveyor stop. Deviating from this embodiment, for example, by changing the position of the control cross sections 77 this difference can be varied. In particular, the metering unit 21 be executed so that the delivery stop pressure and the maximum pressure are identical and the delivery stop operation of the metering unit 21 thus deleted. Such a metering unit 21 goes with continuously increasing pressure in the high-pressure range 45 directly from the partial delivery to the pressure limit.

In an embodiment not shown are the valve spool 73 and the bolt 93 made in one piece to the number of parts of the fuel pump 5 to reduce.

The 6 to 8th show a fuel pump 5 with integrated metering unit 21 , A pump housing 101 the fuel pump 5 has a hole 103 on, within the metering unit 21 is arranged (see 8th ). The hole 103 is opposite to a longitudinal axis 107 the fuel pump 5 staggered. The hole 103 has an in 8th upper section of larger diameter and one in 8th lower section of smaller diameter. About the federal government 69 is the metering unit 21 firmly in the section of the hole 103 inserted with a larger diameter. The Bund 69 also serves to seal, so that no fuel on the metering unit 21 past that above the hole 103 arranged pressure damper 19 in the workroom 33 can get. The larger diameter section of the hole 103 is hydraulically downstream of the second valve means 25 and upstream of the inlet valve 31 ,

The smaller diameter section of the hole 103 is hydraulic on only in 6 apparent way with the high pressure area 45 connected: how out 6 it can be seen, is the connection line 47 for connecting the smaller diameter portion of the bore 103 with the high pressure area 45 as a bore, the off-center in the pump housing 101 is, executed. The sealing element 67 seals the annular spaces between the two sections of the bore 103 and the housing 61 So ultimately the high pressure area 45 against the low pressure area 22 in the area of the bore 103 from each other. In this case, there is that side of the cylinder-like housing 61 the metering unit 21 in the high pressure area 45 that the first valve device 23 has (in 8th the bottom side of the case 61 ). So fuel only through the throttle 95 in the metering unit 21 can enter, closes the mounting collar 88 the housing socket 87 the metering unit 21 between the use 96 and the wall of the housing 61 , It can be seen that the sealing points are inside the fuel pump 5 are located. The fuel pump 5 thus has no sealing point to the outside. A possible leak on the Bund 69 or on the sealing element 67 only affects within the fuel pump 5 out, that is, due to such a leak can not fuel from the fuel pump 5 escape.

To connect the metering unit 21 with the inlet valve 31 are a first connection hole 109 and a second connection hole 111 intended. The first connection hole 109 ends in the high pressure area 45 However, the first connection hole is 109 to the high pressure area 45 with a sealing piece 113 locked.

QUOTES INCLUDE IN THE DESCRIPTION

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Cited patent literature

• DE 102004048594 A1 [0002]

Claims (13)

Fuel pump ( 5 ), in particular for a fuel system ( 1 ) an internal combustion engine ( 11 ), with a first valve device ( 23 ) between a high pressure area ( 45 ) and a low pressure area ( 22 ) of the fuel pump ( 5 ), and a second valve device ( 25 ), which in the flow direction in front of an inlet ( 31 ) a pumping device ( 46 ) for fuel delivery from the low pressure area ( 22 ) in the high pressure area ( 45 ), characterized in that the first valve device ( 23 ) and the second valve device ( 25 ) are coupled to one another such that a movement of the first valve device ( 23 ) in the opening direction, a closing movement of the second valve device ( 25 ) causes. Fuel pump ( 5 ) according to claim 1, characterized in that the first valve device ( 23 ) and the second valve device ( 25 ) are coordinated with one another such that the first valve device ( 23 ) completely closed and the second valve device ( 25 ) is fully opened when a pressure in the high pressure area ( 45 ) is less than a minimum pressure. Fuel pump ( 5 ) according to claim 1 or 2, characterized in that the first valve device ( 23 ) and the second valve device ( 25 ) are coordinated so that at a pressure in the high pressure region ( 45 ) above the minimum pressure, an opening degree of the second valve device ( 25 ), the lower the higher the pressure in the high-pressure region ( 45 ). Fuel pump ( 5 ) according to one of claims 1 or 2, characterized in that the first valve device ( 23 ) and the second valve device ( 25 ) are coordinated so that when reaching or exceeding a maximum pressure in the high-pressure region ( 45 ) the first valve device ( 23 ) and the second valve device ( 25 ) is closed. Fuel pump ( 5 ) according to one of the preceding claims, characterized in that between the high pressure area ( 45 ) and the first valve device ( 23 ) a throttle ( 95 ) is arranged. Fuel pump ( 5 ) according to one of the preceding claims, characterized in that the first ( 23 ) and the second ( 25 ) Valve device in a common cylinder-like housing ( 61 ) are arranged. Fuel pump ( 5 ) according to claim 6, characterized in that the first valve device ( 23 ) as a slide valve ( 23 ) with a housing socket ( 87 ) and a bolt-shaped valve element ( 93 ), wherein the housing bush ( 87 ) in the housing ( 61 ), preferably pressed. Fuel pump ( 5 ) according to claim 7, characterized in that the housing bush ( 87 ) a fastening collar ( 88 ), the axially from the bolt-shaped valve element ( 93 ) is located away. Fuel pump ( 5 ) according to one of claims 6 to 8, characterized in that the bolt-shaped valve element ( 93 ) at one end of the pressure in the high pressure region ( 45 ) and at the other end of a valve element ( 73 ) of the second valve device ( 25 ) is applied. Fuel pump ( 5 ) according to one of claims 7 to 9, characterized in that between the high pressure area ( 45 ) and the first valve device ( 23 ) arranged throttle ( 95 ) through a bottleneck in the inlet area ( 89 ) of the housing socket ( 87 ) is formed. Fuel pump ( 5 ) according to one of claims 6 to 10, characterized in that the second valve device ( 25 ) as a slide valve ( 25 ) with a spring-loaded piston-like valve element ( 73 ) is trained. Fuel pump ( 5 ) according to claim 7, characterized in that the piston-like valve element ( 73 ) of the second valve device ( 25 ) and the bolt-shaped valve element ( 93 ) of the first valve device ( 23 ) are integrally connected. Fuel pump ( 5 ) according to one of claims 5 to 12, characterized in that the cylinder-like housing ( 61 ) a covenant ( 69 ) and / or a sealing element ( 67 ) for connection to a housing ( 101 ) of the fuel pump ( 5 ) having.