EP2954192B1 - High pressure pump - Google Patents

Description

The present invention relates to a valve according to the preamble of claim 1, a high-pressure pump according to the preamble of claim 4 and a high-pressure injection system according to the preamble of claim 15.

State of the art

In high-pressure injection systems for internal combustion engines, in particular in common-rail injection systems of diesel or gasoline engines, a high-pressure pump continuously ensures the maintenance of the pressure in the high-pressure accumulator of the common-rail injection system. The high-pressure pump can be driven, for example, by a camshaft of the internal combustion engine by means of a drive shaft. For the promotion of the fuel to the high-pressure pump Vorförderpumpen, z. B. a gear or rotary vane pump used, which are connected upstream of the high-pressure pump. The prefeed pump delivers the fuel from a fuel tank through a fuel line to the high pressure pump. The WO 2012/136429 A shows a high-pressure pump for conveying a fluid. Amongst others, piston pumps are used as high-pressure pumps. In a housing, a drive shaft is mounted. Radially to pistons are arranged in a cylinder. On the drive shaft with at least one cam is a roller with a roller rolling surface, which is mounted in a roller shoe. The roller shoe is connected to the piston, so that the piston is forced to oscillate translational motion. A spring applies to the roller shoe a radially directed to the drive shaft force, so that the roller is in constant contact with the drive shaft. The roller stands with the roller rolling surface on a shaft rolling surface as the surface of the drive shaft with the at least one cam in contact with the drive shaft. The roller is mounted by means of a sliding bearing in the roller shoe.

The drive shaft with the at least one cam, the roller and the roller shoe are arranged within a lubricant space of the high-pressure pump. Through this lubrication chamber, fuel delivered by the prefeed pump to the high-pressure pump is passed in order, on the one hand, to lubricate the components within the lubricant space and to cool them with the fuel conducted through the lubricant space. The fuel delivered by the prefeed pump to the high-pressure pump thus comprises in volume flow on the one hand the fuel passed through the lubricant space for lubricating and cooling the components of the high-pressure pump within the lubricant space and the fuel intended for the high-pressure pump for delivery under high pressure to the high-pressure rail. It should be present at a fuel line from the pre-feed pump to the high-pressure pump, a substantially constant pressure. For this reason, an overflow valve is arranged in a flow channel from the prefeed pump to the lubricating space or from the lubricating space to a fuel tank. The overflow valve is disposed within a recess of a housing of the high-pressure pump. Above a predetermined pressure, z. B. 5.5 bar, opens the spill valve and thereby passes more fuel through the lubricating space and this passed through the lubricating space fuel is returned to the fuel tank. At a drop in pressure before the spill valve, z. B. below 4.5 bar, closes the spill valve.

Such overflow valves have a valve cylinder and a closing piston on which is movably mounted on a cylinder between a closed position and an open position. Through an inlet opening, fuel can be introduced into the overflow valve and discharged out of the overflow valve through a drain opening. On the one hand, the pressure of the fuel at the inlet opening and also a spring acts on the closing piston. The forces under pressure from the spring and the fuel, which act on the closing piston, are oppositely directed so that the closing piston moves within the cylinder at a different pressure of the fuel at the inlet opening. The drain openings opening into a cylinder space enclosed by the cylinder are in the closed position of Locking piston closed. Only when the pressure at the inlet opening is increased by the fuel does the closing piston move into an open position, in which the outlet openings on the cylinder chamber are not closed by the closing piston.

The cylinder chamber is divided into a first cylinder part space and a second cylinder part space as a spring chamber of the closing piston. In the second cylinder space or spring chamber, the spring is arranged and opens into the spring chamber through the valve cylinder, a compensation opening. The spring chamber is filled with fuel during normal operation and the compensation opening serves to allow a lifting movement of the closing piston, since during the lifting movement of the closing piston, the volume of the spring chamber is changed. In this case, the compensation opening with the spring chamber also causes a damping of the lifting movement of the Schließkobens, as the displaced by the closing piston in the spring chamber fuel can flow only through the compensation opening at a reduction in the volume of the spring chamber and vice versa. In the case of a fuel return line from the high-pressure pump or the lubricant chamber to a fuel tank with no or a low return pressure in the fuel return line, the spring chamber or an air filling of the lubricant chamber may be emptied. As a result, occurs after a restart of the high pressure pump to the closing piston over a longer period or constantly no damping by the fuel within the spring chamber, which can lead to oscillations of the closing piston and a resulting noise and additional mechanical loads or wear of the spill valve.

The DE 10 2009 026 596 A1 shows a high-pressure pump for conveying a fluid, in particular fuel, comprising a drive shaft, at least one piston, at least one cylinder for supporting the piston, wherein the at least one piston indirectly or directly on the at least one cam is supported, so that of the at least one piston a translational movement due to a rotational movement of the drive shaft is executable.

Disclosure of the invention Advantages of the invention

Not according to the invention valve, in particular overflow valve, for arrangement in a recess of a housing of a high pressure pump, comprising a valve housing with a valve cylinder, a movable within the valve cylinder between a closed position and open position closing piston, so that closed in the closed position and the valve in the open position an inlet opening for supplying a fluid within a cylinder space enclosed by the valve cylinder, at least one drain opening for discharging the fluid introduced into the cylinder space, an elastic valve element connected to the closing piston, in particular valve spring, with which a pressure force can be applied to the closing piston, which is oriented opposite to a pressure force which can be applied to the closing piston by the fluid within the cylinder space, so that the closing piston is aligned by means of the elastic valve ement and the fluid applied to the closing piston pressure force between the closed position of the open position is movable, wherein the valve housing on the outside has no fixing device, in particular no thread or no bayonet connection, for axial mounting in the recess on the housing of the high-pressure pump. On the valve housing on the outside no fixing device, in particular no thread or no external thread is formed, for axial attachment to the housing of the high-pressure pump in the recess. As a result, an intermediate space between the valve housing and the housing of the high-pressure pump can be flowed through axially by the fluid. The axial fixation of the valve within the recess of the housing is generally carried out by the support on a first inner end and / or a second outer end of the valve and / or by the support on a sealing ring on a sealing groove on the valve and / or the support on a groove, in particular a sealing groove, on the outside of the valve housing, wherein the support of the valve or valve housing takes place on the housing of the high-pressure pump. Notwithstanding this may be formed on the valve housing on the outside an annular projection for axial support and attachment of the valve to the housing of the high-pressure pump.

In an additional example, the cylinder chamber is divided by the closing piston into a first cylinder subspace and a second cylinder subspace, and the inlet port and the at least one drain port open into the first cylinder subspace and the elastic valve element is disposed within the second cylinder subspace as a spring chamber and opens into the second cylinder subspace a compensation opening, in particular radially, through the valve housing.

In a supplementary example, a sealing groove and / or a sealing ring, in particular on the outside, is formed and / or arranged on the valve housing in the direction of a longitudinal axis of the valve only between the inlet opening and the at least one drain opening. Outside of the valve between the inlet opening and the at least one drain opening can thus flow around the outside of the fluid from the valve in an arrangement in the recess of the housing.

Inventive high-pressure pump for conveying fuel, for. As diesel or gasoline, comprising a housing, a drive shaft with at least one cam, at least one piston for conveying fuel, at least one cylinder for supporting the at least one piston, wherein the at least one piston indirectly on the drive shaft with the at least one cam is supported, so that from the at least one piston is a translational movement due to a rotational movement of the drive shaft executable, a lubricating space, formed in the housing recess for arranging a spill valve, an arranged within the recess overflow valve with an inlet opening and at least one drain opening, wherein the recess a first inner end and a second outer end and the second outer end of the recess for passing fuel through the lubricating space, and preferably for discharging fuel from the recess serves as a flow channel. Thus, the fuel can be passed through the second outer end of the recess, so that advantageously flows through a gap between the valve housing and the housing of the high-pressure pump, starting from the at least one drain opening in the direction of the second outer end of the spill valve of the fuel is and therefore also very easy air in this space by means of passing fuel through the gap can be easily removed at the second outer end by the supply of fuel.

In a complementary embodiment, a recess inlet channel opens into the recess and the inlet opening of the overflow valve has a smaller distance in the direction of a longitudinal axis of the recess to a mouth of the recess inlet channel into the recess than the at least one drain opening of the overflow valve and / or the recess is as a bore educated. Fuel can be introduced into the recess through the recess inlet channel, and from a section of the recess, starting with the first inner end to the inlet opening of the overflow valve, the fuel can thus be introduced from the recess inlet channel through the recess into the inlet opening of the overflow valve.

Suitably, a sealing ring is formed between the housing of the high-pressure pump and the overflow valve, and preferably the sealing ring is aligned in the direction of the longitudinal axis of the recess between the inlet opening and the at least one drain opening. The sealing ring divides the recess into a first partial recess from the first inner end of the recess to the sealing ring and a second partial recess from the sealing ring to the second outer end of the recess. The first and second part of the recess are separated fluid-tight with the sealing ring and fuel can be passed from the first part of the recess to the second part recess only by opening the spill valve.

In an additional variant, in the region of the second outer end of the recess, a connection, in particular a return connection, is arranged with a connection channel within the recess, and the connection channel serves for the passage of fuel.

In an additional embodiment, an outer axial end of the overflow valve rests on the neck, so that the overflow valve is thereby secured in the recess in the axial direction. The second outer end of the overflow valve, in particular of the valve housing, rests on the connecting piece, so that thereby the overflow valve in the axial direction in the recess is attached. Appropriately, the overflow valve in the axial direction in addition to the sealing ring on the housing of the high-pressure pump, so that thereby the valve is fixed in both axial directions on the housing of the high-pressure pump.

In a supplementary embodiment of the nozzle is connected by means of a press connection with the housing of the high-pressure pump within the recess. By means of the press assembly of the nozzle is particularly simple and reliable mechanically fastened to the housing of the high-pressure pump within the recess, and in addition thereby the second outer end of the recess is fluid-tight manner, so that emerge only through the nozzle channel fuel from the recess at the second outer end of the recess can.

In a supplementary variant, the overflow valve of the high pressure pump is designed as an overflow valve described in this patent application.

Suitably, in the axial direction of the overflow valve between the drain opening of the spill valve and the outer axial end of the spill valve between the valve housing and the housing of the high-pressure pump, a particular annular space is formed for passing the fuel from the drain opening to the outer axial end of the spill valve and preferably to the second end of the recess. In the case of an open closing piston, the fuel can flow into the first cylinder subspace through the inlet opening of the valve and flow out of it through at least one discharge opening into the intermediate space. Subsequently, the fuel emerging from the at least one drain opening flows around the overflow valve between the valve housing and the housing of the high-pressure pump in the axial direction, that is to say in the direction of a longitudinal axis of the valve from the first inner end of the overflow valve to a second outer end of the overflow valve.

In an additional embodiment, the stroke volume of the valve piston is greater than the volume of the gap. The stroke volume of the valve piston is the volume in the first and / or second cylinder subspace, which displaces the closing piston between the open position and the closed position.

In a supplementary variant, the intermediate space is divided into an axial part intermediate space between a compensation opening in the second Zylinderteilraumes as a spring chamber and the outer axial end of the spill valve and the stroke volume of the valve piston is greater than the volume of the sub-gap. The compensation opening on the valve housing opens from the second cylinder chamber or spring chamber to the intermediate space between the valve housing and the housing of the high-pressure pump. With air in the sub-gap can thus be filled by a movement or lifting movement of the closing piston between the open position and the closed position of the entire partial gap with fuel. As a result, a particularly safe and reliable filling of the partial gap with fuel is possible, provided that at a partially switched off high-pressure pump, the partial gap is at least partially, in particular completely, filled with air. When the high-pressure pump is restarted, the partial interspace, in particular also the intermediate space, can be refilled with fuel in a particularly simple manner, so that no oscillations of the closing piston occur as a result of the second cylinder subspace or the spring chamber being particularly easily and reliably re-fueled through the equalization opening can be filled.

In a supplementary variant, the inlet opening of the overflow valve is formed at an inner axial end of the overflow valve.

Inventive high-pressure injection system for an internal combustion engine, in particular for a motor vehicle, comprising a high pressure pump with a lubrication chamber and a spill valve, a prefeed pump, a high pressure rail, wherein the spill valve is designed as a described in this patent application spill valve and / or the high pressure pump as one in this Patent application described high-pressure pump is formed.

In a supplementary embodiment, a spring holder is disposed within the valve cylinder and the spring holder is connected to the elastic valve element.

Preferably, the elastic valve element is disposed within the cylinder space.

Suitably, the at least one drain opening in the closed position of the closing piston is closed by the closing piston and / or the at least one drain opening opens into the opening of the closing piston in the first cylinder part space.

In a further embodiment, a compensation opening for introducing and discharging the fluid into and out of the second cylinder subspace opens into the second cylinder subspace. The compensation opening serves to introduce fuel into the second Zylinderteilraum and divert. During a movement of the closing piston, the volume of the second cylinder part space changes. In order for any movement of the closing piston to be possible with an incompressible fuel, it is necessary for the fluid to be able to flow in and out of the second cylinder space through the compensation opening with a very small flow cross-sectional area. At the inlet opening can also pressure fluctuations occur. Such, in particular short-term, pressure fluctuations would lead to a vibration or vibration movement of the closing piston. In a small-sized compensation opening and a, in particular complete, filling of the second Zylinderteilraumes with liquid, especially fuel, thereby such vibrations or rapid reciprocating movements of the closing piston due to pressure fluctuations can be counteracted and the movement of the closing piston takes place slowly attenuated only due a permanent change in pressure of the liquid at the inlet opening, so that when filling the second Zylinderteilraumes with the liquid, in particular fuel, no vibrations of the closing piston and resulting noise and mechanical wear occurs.

In a supplementary variant, the at least one drain opening opens into the second cylinder part space, in particular in all positions of the closing piston.

In a further embodiment, the valve is at least partially, in particular completely, made of metal, for. As steel or aluminum, and / or plastic. Metal is a particularly durable and durable material for the manufacture of the valve. Plastic advantageously has a low weight, so that thereby the valve has a low weight. Preferably, a plastic is a glass fiber reinforced plastic. Preferably, the valve cylinder or the valve housing and / or the closing piston and / or the spring holder at least partially, in particular completely, made of plastic.

In a supplementary variant, the volume flow of the fuel delivered by the prefeed pump to the high-pressure pump is controlled and / or regulated during operation of the internal combustion engine by controlling and / or regulating the delivery rate of the prefeed pump or by means of a metering unit to the flow cross-sectional area of a flow channel from the prefeed pump the high-pressure pump is controlled and / or regulated. If the prefeed pump can be controlled or regulated in the delivery rate, no metering unit is required and the volume flow of the fuel supplied to the high-pressure pump is controlled and / or regulated by the prefeed pump. If the prefeed pump can not be controlled and / or regulated in the delivery rate, this is done with the metering unit.

In a further embodiment, the prefeed pump comprises an electric motor.

In particular, the electric motor of the prefeed pump is integrated in the prefeed pump, z. B. by permanent magnets are installed in a gear.

The producible by the high-pressure pump pressure in the high-pressure rail is, for example, in the range of 1000 to 3000 bar z. B. for diesel engines or between 40 bar and 400 bar z. B. for gasoline engines.

Brief description of the drawings

Fig. 1

einen Querschnitt einer Hochdruckpumpe zum Fördern eines Fluides,

Fig. 2

einen Schnitt A-A gemäß Fig. 1 einer Laufrolle mit Rollenschuh und einer Antriebswelle,

Fig. 3

eine stark schematisierte Ansicht eines Hochdruckeinspritzsystems,

Fig. 4

einen stark vereinfachten Querschnitt der Hochdruckpumpe mit einer Vorförderpumpe,

Fig. 5

einen Längsschnitt eines aus dem Stand der Technik bekannten Überströmventiles,

Fig. 6

einen Längsschnitt eines erfindungsgemäßen Überströmventiles,

Fig. 7

einen Längsschnitt eines Gehäuses der Hochdruckpumpe mit dem erfindungsgemäßen Überströmventil in einer Aussparung des Gehäuses.

Hereinafter, embodiments of the invention will be described in more detail with reference to the accompanying drawings. It shows:

Fig. 1

a cross section of a high-pressure pump for conveying a fluid,

Fig. 2

a section AA according to Fig. 1 a roller with roller shoe and a drive shaft,

Fig. 3

a highly schematic view of a high-pressure injection system,

Fig. 4

a greatly simplified cross-section of the high-pressure pump with a prefeed pump,

Fig. 5

a longitudinal section of a known from the prior art spill valve,

Fig. 6

a longitudinal section of a Überströmventiles invention,

Fig. 7

a longitudinal section of a housing of the high-pressure pump with the overflow valve according to the invention in a recess of the housing.

Embodiments of the invention

In Fig. 1 is a cross section of a high-pressure pump 1 for conveying fuel shown. The high-pressure pump 1 serves to fuel, z. As gasoline or diesel, to promote an internal combustion engine 39 under high pressure. The pressure which can be generated by the high-pressure pump 1 is, for example, in a range between 1000 and 3000 bar.

The high-pressure pump 1 has a drive shaft 2 with two cams 3, which performs a rotational movement about a rotation axis 26. The axis of rotation 26 lies in the plane of Fig. 1 and is perpendicular to the Drawing plane of Fig. 2 , A piston 5 is mounted in a cylinder 6, which is formed by a housing 8. A working chamber 29 is bounded by the cylinder 6, the housing 8 and the piston 5. Into the working space 29 opens an inlet channel 22 with an inlet valve 19 and an outlet channel 24 with an outlet valve 20. Through an inlet opening on the inlet channel 22, the fuel flows into the working space 29 and through an outlet opening 23 on the outlet channel 24, the fuel flows under high pressure out of the work space 29 again. The inlet valve 19, z. As a check valve, is designed to the effect that only fuel can flow into the working space 29 and the exhaust valve 20, z. B. a check valve is designed to the effect that only fuel can flow out of the working space 29. The volume of the working chamber 29 is changed due to an oscillating stroke movement of the piston 5. The piston 5 is indirectly supported on the drive shaft 2 from. At the end of the piston 5 or pump piston 5, a roller shoe 9 is attached to a roller 10. The roller 10 can perform a rotational movement, the axis of rotation 25 in the plane according to Fig. 1 lies and perpendicular to the plane of Fig. 2 stands. The drive shaft 2 with the at least one cam 3 has a shaft rolling surface 4 and the roller 10 has a roller rolling surface 11.

The roller-running surface 11 of the roller 10 rolls on a contact surface 12 on the shaft rolling surface 4 of the drive shaft 2 with the two cams 3 from. The roller shoe 9 is mounted in a roller shoe bearing formed by the housing 8 as a sliding bearing. A spring 27 or spiral spring 27 as an elastic element 28, which is clamped between the housing 8 and the roller shoe 9, applies a compressive force to the roller shoe 9, so that the roller rolling surface 11 of the roller 10 is in constant contact with the shaft roller 9. Rolling surface 4 of the drive shaft 2 is. The roller shoe 9 and the piston 5 thus carry out together an oscillating stroke movement. The roller 10 is mounted with a sliding bearing 13 in the roller shoe 9.

In Fig. 3 is a highly schematic representation of a high-pressure injection system 36 for a motor vehicle not shown mapped with a high-pressure rail 30 or a fuel rail 31. From the high-pressure rail 30 and a fuel rail 31, the fuel by means of valves (not shown) in the combustion chambers (not shown) of the internal combustion engine 39 injected. An electric prefeed pump 35 delivers fuel from a fuel tank 32 through a fuel line 33 to the high pressure pump 1. The high pressure pump 1 is driven by the drive shaft 2 and the drive shaft 2 is a shaft, for. A metering unit 37 controls and / or regulates the per unit time to the high-pressure pump 1 passed volume of fuel. The high-pressure rail 30 serves to inject the fuel into the combustion chamber of the internal combustion engine 39. The fuel not required by the high-pressure pump 1 is returned to the fuel tank 32 through an optional fuel return line 34.

Fig. 4 shows a part of the high pressure injection system 36. Within the housing 8 of the high pressure pump 1, a lubricating space 40 is formed. In the lubricating space 40 are the drive shaft 2, the roller 10, the roller shoe 9 (not in Fig. 4 ) and partially the piston 5 is arranged. By passing through the lubricant space 40 fuel these components 2, 5, 9 and 10 are lubricated by the fuel. Within the housing 8, a flow channel 43 is provided for this purpose, and the fuel is introduced into the lubricating space 40 through the flow channel 43 and then discharged again and returned to the fuel tank 32 after being discharged from the lubricating space 40 through the fuel return line 34 ( Fig. 4 ). In Fig. 4 is that in Fig. 3 shown high-pressure injection system 36 shown in more detail without the high-pressure rail 30 and without the internal combustion engine 39. In this case, the high-pressure injection system 36 in the in Fig. 4 illustrated detailed embodiment in contrast to the in Fig. 3 illustrated embodiment, no metering unit 37. The prefeed pump 35 is in the in Fig. 4 illustrated embodiment in the flow rate controllable and / or regulated and is driven by an electric motor 17. The prefeed pump 35 is a gear pump 14, z. B. an internal gear pump 15 or an external gear pump 16, formed and shown greatly simplified. The sucked by the prefeed pump 35 from the fuel tank 32 fuel is supplied from the prefeed pump 35 with a prefeed, z. B. 4 bar, fed through the fuel line 33 of the high-pressure pump 1, that is, the inlet channel 22 of the high pressure pump 1 is supplied. Further, the fuel delivered by the prefeed pump 35 during operation of the engine 39 after passing through through the lubrication chamber 40 through an overflow valve 41 and the overflow valve 41 downstream flow channel 43 derived from the lubrication chamber 40 for lubrication, z. B. the drive shaft 2, the roller 10 and the piston 5. After flowing through the fuel through the lubricating space 40, the fuel is again supplied through the flow channel 43 and the fuel return line 34 to the fuel tank 32. As a result, these components 2, 5, 9 and 10 can be lubricated as well as cooled. The overflow valve 41 is designed such that in the fuel line 43 in front of the overflow valve 41 and in the fuel line 43 in the lubricating chamber 40, a constant pressure, ie the prefeed pressure of 4, 5 bar prevails. The prefeed pump 35 thereby promotes not only the flow rate for the high-pressure pump 1 to fuel but also an additional amount of fuel for lubrication of the high-pressure pump 1, ie the fuel flowing through the lubricating space 40. In order to avoid an increase in the pressure at an increased delivery rate of the prefeed pump 35 to the fuel line 33 in front of the overflow 41, opens at a pressure increase, for. B. from a pressure of 5.5 bar, the fuel in front of the spill valve 41, the spill valve 41 in addition, ie provides a larger flow cross-sectional area of the fuel through the spill valve 41 as long until again a pressure of 4.5 bar in front of the spill 41st prevails. At a pressure of less than 4.5 bar in the fuel line 33 before the spill valve 41, the spill valve 41 closes. As a result, in the fuel line 33 before the spill valve 41 during operation of the internal combustion engine 39, a substantially constant prefeed pressure between 4.5 and 5.5 bar are made available, even with minor fluctuations in the flow rate of the feed pump 35 with respect to the volume flow required by the high-pressure pump 1.

In Fig. 5 a known from the prior art valve 42 is shown as overflow valve 41 of the high-pressure injection system 36. The overflow valve 41 has a valve housing 45, which limits a valve cylinder 44. On the outside of the valve housing 45, a thread 60 is formed as an external thread 60, which forms a fixing device 38 for axial attachment within a recess 61 on the housing 8 of the high-pressure pump 1. Within the valve cylinder 44, a closing piston 46 is mounted. The closing piston 46 can due to the Slide bearing on the valve cylinder 44 an axial movement, ie as shown in FIG Fig. 6 from left to right and vice versa. The valve cylinder 44 and the valve housing 45 include a cylinder chamber 56 a. In this case, the cylinder chamber 56 is subdivided by the closing piston 46 into a first cylinder subspace 57 and a second cylinder subspace 58. In the first cylinder part space 57 opens an inlet opening 47 for fluid, in particular fuel, since in the valve housing 45 an inlet channel 48 is incorporated. The inlet channel 48 is formed in the axial direction in the valve housing 45. Furthermore, two drainage openings 49 open into the first cylinder part space 57, because two radial discharge passages 50 are incorporated into the valve housing 45. The closing piston 46 or the cap 46 is mounted on the valve cylinder 44 at an axial section with a larger diameter or radius by means of a plain bearing. At a second portion of the closing piston 46 has a smaller diameter and in the right end portion of this section with the smaller diameter, the closing piston 46 has a sealing seat 54.

In the second cylinder part space 58, a valve spring 52 is arranged as an elastic valve element 51. The elastic valve element 51 is attached at one end to a fixed spring holder 53 and at another end to the closing piston 46. The spring holder 53 closes the valve cylinder 44 and is formed as a separate component in addition to the valve housing 45. Notwithstanding this, the spring holder 53 may also be formed integrally with the valve housing 45 (not shown). On the outside, 45 two sealing grooves 62 are formed on the valve housing, in each of which a sealing ring 63, z. B. an elastic rubber seal is arranged. By means of the sealing rings 63, the valve housing 45 can thereby be integrated or installed in the housing 8 of the high-pressure pump. For this purpose, the housing 8 of the high-pressure pump 1 has a correspondingly complementary hole 64 or opening as a recess 61, on which the sealing rings 63 rest and thereby the flow channel 43 through the inlet channel 48 and the two drain channels 50 can be performed.

In Fig. 5 a partial opening position of the closing piston 46 is shown. In this partial opening position, the two drain openings 49 are partially closed by the portion of the closing piston 46 with the larger diameter and partly, the fluid can flow out of the first cylinder subspace 57 through the two drainage openings 49. The fluid, in particular the fuel, flows through the inlet channel 48 into the first cylinder subspace 57. Increases the pressure of the fuel in the first cylinder part space 57 on, z. B. to a value of more than 5 bar moves due to the greater pressure of the fuel in the first cylinder part space 57 of the closing piston 46 against the force applied by the valve spring 52 compressive force further to the left, so that thereby the two flow channels 50 are opened further. When the pressure drops, the closing piston 46 moves to the right until the sealing seat 54 completely closes the inlet channel 48 or the inlet opening 47 opening into the first cylinder-part space 57. During the movement of the closing piston 46, the volume of the second cylinder part space 58 also changes. There is little play between the closing piston 46 with the section with the larger diameter and the valve cylinder 44, so that fuel also flows from the first cylinder part space 57 to a very small extent in the second cylinder part space 58 passes. The second cylinder subspace 58 is thus, provided that the second cylinder subspace 58 or spring chamber 58 is not filled with air due to a low pressure in the fuel return line 34, filled with the substantially incompressible fuel. In order to allow movement of the closing piston 46 at all, it is necessary that the fuel located in the second cylinder part space 58 can be guided outwardly through a compensation opening 59 from the second cylinder part space 58 and back inside. In this case, the compensation opening 59 has a very small diameter or a small flow cross-sectional area, for. B. a diameter in the range between 0.5 mm and 1 mm. Pressure fluctuations of the fuel in the region of the inlet opening 47 do not cause a vibration of the closing piston 46, since only slowly fuel is introduced and discharged through the compensation opening 59 into the second cylinder subspace 58 and thereby damped only in the long term pressure changes of the fuel in the region of the inlet opening 47 Movement of the closing piston 46 is effected. The sealing seat 54 advantageously allows a complete sealing of the overflow valve 41 in the closed position of the closing piston 46.

In Fig. 6 is a longitudinal section of a spill valve 41 according to the invention shown. In the following, essentially only the differences become the in Fig. 5 described overflow valve 41 described in the prior art. The valve housing 45 has on the outside no thread 60 as a fixing device 38 for the axial attachment of the valve housing 45 to a housing 8 of the high-pressure pump 1. The overflow valve 41 according to the invention can thus not in the axial direction, that is in the direction of a longitudinal axis 77 of the valve 42 and a longitudinal axis 77 formed as a bore 64 recess 61 on the housing 8 of the high-pressure pump ( Fig. 7 ) are fixed in the axial direction. For the axial attachment of the overflow valve 41, the sealing ring 63 is located on the sealing groove 62 of the valve housing 45 on a shoulder 78 on the housing 8 of the high-pressure pump 1 (FIG. Fig. 7 ) on. The valve 42 has a first inner end 72 and a second outer end 73. On the second outer end 73 of the spill valve 41 is formed as a return pipe 69 nozzle 68. The nozzle 68 is connected by means of a press bond 71 fluid-tight and non-positively connected to the housing 8 of the high-pressure pump 1.

In the housing 8 of the high pressure pump 1 is - as already mentioned - a trained as a bore 64 recess 61 with a longitudinal axis 77 incorporated. The bore 64 has a first inner end 65 and a second outer end 66. Due to the resting of the second outer end 73 of the spill valve 41 on the end of the nozzle 68 and the rest of the sealing ring 63 on the shoulder 78 of the housing 8, the valve 42 is fixed in the axial direction within the bore 64. The overflow valve 41 according to the invention has only between the two drain openings 49 and the inlet opening 47 at the first inner end 72 of the spill valve 41, the sealing ring 63, thereby characterized a gap 74 in the direction of the longitudinal axis 77, starting from the two drain openings 49 and the sealing ring 63 can be flowed through to the second outer end 73 of the overflow valve 41 from the two outflow openings 49 flowing fuel at an open closing piston 46. At the end of the nozzle 68, which is arranged within the bore 64, a plurality of Radialstutzennuten 76 are formed so that the fuel flowing through the gap 74 fuel in the region of the second outer end 73 of the spill valve 41 through these Radialstutzennuten 76 in the radial direction to a nozzle channel 70 can. Due to the sectional formation in Fig. 7 only one of the plurality of Radialstutzennutzen 76 is visible. The annular Gap 74 is additionally subdivided into a fictitious partial gap 75 and the partial gap 75 begins in the axial direction at the compensation opening 49 and ends at the second outer end 73 of the spill valve 41st

Through the recess inlet channel 67 as a flow channel 43, the fuel is discharged from the lubricating chamber 40 and through the nozzle channel 70, the fuel is supplied through the nozzle channel 70 as a flow channel 43 of the fuel return line 34. The fuel return line 34 (not in Fig. 7 shown) is attached to the outer end of the nozzle 68. The fuel flows through an opening 79 of the recess inlet channel 67 into the recess 61 and from the recess 61 through the inlet channel 48 in the spill valve 41 at an open closing piston 46. From the first cylinder part space 57, the fuel flows through the two drain openings 49 in the intermediate space 74 and from the intermediate space 74 in the nozzle channel 70 as a flow channel 43, so that the second outer end of the recess 61 serves as a flow channel 43.

The fuel return line 34 has no constriction or no dynamic pressure, so that when the high-pressure pump 1 and a pre-feed pump 35 are switched off, the fuel return line 34 and therefore also the nozzle channel 70 and the intermediate space 74 of fuel runs empty, ie is filled with air. When commissioning the high-pressure pump 1 and the prefeed pump 35, the prefeed pump 35 is designed in terms of delivery that in normal operation, the closing piston 46 is slightly opened to ensure cooling of the components within the lubricating space 40. As a result, due to the opened closing piston 46 with the commissioning of the prefeed pump 35 constantly flows through the gap 74 of fuel and thus the nozzle channel 70 so that a possible existing air volume in the gap 74 and the nozzle channel 70 is immediately filled with fuel and thereby the air is removed from the intermediate space 74 in a very short time after starting the prefeed pump 35 and the high-pressure pump 1. The spring chamber 58 or the second cylinder subspace 58 is in fluid-conducting connection with the compensation opening 49 with the intermediate space 74 or the partial interspace 75. As a result, after the prefeed pump 35 has been started and the high-pressure pump 1, an existing in the spring chamber 58 volume of air through the equalization opening 59 quickly and quickly filled with fuel, since due to the lifting movement of the closing piston 46 and the existing filling of the gap 74 with fuel immediately fuel flow into the spring chamber 58 can and thus the spring chamber 58 can be filled after starting the high pressure pump 1 and the prefeed pump 35 in a short time with fuel. Due to this rapid filling after starting the prefeed pump 35 and the high-pressure pump 1 of the spring chamber 58 with fuel damping of the closing piston 46 is ensured quickly, so that no vibration movements of the closing piston 46 occur.

Overall, significant advantages are associated with the high-pressure pump 1 according to the invention. The fuel return line has no restriction and thus no back pressure to reduce energy consumption. When the high-pressure pump 1 is switched off and the prefeed pump 35 is switched off, air can thus enter the intermediate space 74 and also the spring chamber 51. After starting the high-pressure pump 1 and the feed pump 35 is due to the dimensioning of the spill valve 41, the gap 74 immediately filled with fuel in a short time and due to the fluid-conducting connection of the gap 74 in the spring chamber 58 through the equalization port 59 and the spring chamber 58 in Be filled with fuel for a short time, so that no vibration movements occur on the closing piston 46 over a longer period of time.

Claims (15)

1. High-pressure pump (1) for delivering fuel, for example diesel or gasoline, comprising

   - a housing (8),

   - at least one piston (5) for delivering fuel,

   - at least one cylinder (6) for the mounting of the at least one piston (5),

   - a recess (61) which is formed in the housing (8) and which serves for the arrangement of an overflow valve (41),

   - an overflow valve (41) which is arranged within the recess (61) and which has an inlet opening (47) and at least one outlet opening (49), wherein the recess (61) has a first, inner end (65) and a second, outer end (66),
   the overflow valve (41) comprising

   - a valve housing (45) with a valve cylinder (44),

   - a closing piston (46) which is movable within the valve cylinder (44) between a closed position and an open position, such that in the closed position, the valve (42) is closed, and in the open position, the valve (42) is open,

   - an inlet opening (47) for the feed of a fluid within a cylinder chamber (56) enclosed by the valve cylinder (44),

   - at least one outlet opening (49) for the discharge of the fluid that has been introduced into the cylinder chamber (56),

   - an elastic valve element (51), in particular valve spring (52), which is connected to the closing piston (46) and by means of which a pressure force can be exerted on the closing piston (46), which pressure force is oriented oppositely to a pressure force that can be imparted on the closing piston (46) by the fluid within the cylinder chamber (56), such that the closing piston (46) is movable between the closed position and the open position by means of the pressure force exerted on the closing piston (46) by the elastic valve element (51) and by the fluid, wherein

   - the valve housing (45) has, on the outer side, no fixing device (38) for axial fastening in the recess (61) on the housing (8) of the high-pressure pump (1),

   characterized in that
   the high-pressure pump comprises a drive shaft (2) with at least one cam (3) and comprises a lubrication chamber (40), wherein the at least one piston (5) is supported indirectly on the drive shaft (2) by means of the at least one cam (3), such that the at least one piston (5) can perform a translational movement on the basis of a rotational movement of the drive shaft (2), and the second, outer end (66) of the recess (61) serves for conducting fuel through the lubrication chamber (40), and
   the cylinder chamber (56) is divided by the closing piston (46) into a first cylinder chamber part (57) and a second cylinder chamber part (58), and the inlet opening (47) and the at least one outlet opening (49) open into the first cylinder chamber part (57), and the elastic valve element (51) is arranged within the second cylinder chamber part (58) as spring chamber (58), and a compensation opening (59) opens into the second cylinder chamber part (58) through the valve housing (45).
2. High-pressure pump according to Claim 1, characterized in that
   the second, outer end (66) of the recess (61) serves as a flow duct (43) for conducting fuel out of the recess (61).
3. High-pressure pump according to Claim 1 or 2, characterized in that
   the valve housing (45) has, on the outer side, no thread (60) for axial fastening in the recess (61) on the housing (8) of the high-pressure pump (1).
4. High-pressure pump according to one or more of the preceding claims,
   characterized in that
   the compensation opening (59) opens out radially through the valve housing (45).
5. High-pressure pump according to one or more of the preceding claims,
   characterized in that,
   in the direction of a longitudinal axis (77) of the valve (42), a sealing groove (62) and/or a sealing ring (63) is formed and/or arranged, in particular at the outside, on the valve housing (45) only between the inlet opening (47) and the at least one outlet opening (49).
6. High-pressure pump according to one or more of the preceding claims,
   characterized in that
   a recess inlet duct (67) opens into the recess (61), and the inlet opening (47) of the overflow valve (41) has a smaller spacing, in the direction of a longitudinal axis (77) of the recess (61), to a mouth (79) of the recess inlet duct (67) into the recess (61) than the at least one outlet opening (49) of the overflow valve (41),
   and/or the recess (61) is formed as a bore (64).
7. High-pressure pump according to one or more of the preceding claims,
   characterized in that
   a sealing ring (63) is formed between the housing (8) of the high-pressure pump (1) and the overflow valve (41), and preferably, in the direction of the longitudinal axis (77) of the recess (61), the sealing ring (63) is oriented between the inlet opening (47) and the at least one outlet opening (49).
8. High-pressure pump according to one or more of the preceding claims,
   characterized in that
   a connector (68), in particular a return connector (69), with a connector duct (70) is arranged within the recess (61) in the region of the second, outer end (66) of the recess (61), and the connector duct (70) serves for conducting fuel.
9. High-pressure pump according to Claim 8, characterized in that
   an outer axial end (73) of the overflow valve (41) lies against the connector (68) such that, in this way, the overflow valve (41) is fixed in the axial direction in the recess (61).
10. High-pressure pump according to Claim 8 or 9, characterized in that
    the connector (68) is connected to the housing (8) of the high-pressure pump (1) within the recess (61) by means of a press fit.
11. High-pressure pump according to one or more of the preceding claims,
    characterized in that
    an in particular ring-shaped intermediate space (74) is formed, between the outlet opening (49) of the overflow valve (41) and the outer axial end (73) of the overflow valve (41) in the axial direction of the overflow valve (41), between the valve housing (45) and the housing (8) of the high-pressure pump (1), which intermediate space serves for conducting the fuel from the outlet opening (49) through to the outer axial end (73) of the overflow valve (41) and preferably to the second end (66) of the recess (61).
12. High-pressure pump according to Claim 11, characterized in that
    the swept volume of the valve piston (46) is larger than the volume of the intermediate space (74).
13. High-pressure pump according to Claim 11 or 12, characterized in that
    the intermediate space (74) is divided into an axial intermediate space part (75) between a compensation opening (59) into the second cylinder chamber part (58) as spring chamber (58) and the outer axial end (73) of the overflow valve (41), and the swept volume of the valve piston (46) is larger than the volume of the intermediate space part (75).
14. High-pressure pump according to one or more of the preceding claims,
    characterized in that
    the inlet opening (47) of the overflow valve (41) is formed on an inner axial end (72) of the overflow valve (41).
15. High-pressure injection system (36) for an internal combustion engine (39), in particular for a motor vehicle, comprising

    - a high-pressure pump (1) with a lubrication chamber (40) and an overflow valve (41),

    - a predelivery pump (35),

    - a high-pressure rail (30),

    characterized in that
    the high-pressure pump (1) is designed according to one or more of the preceding claims.

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