DE102017207983A1 - high pressure pump - Google Patents

Abstract

The invention relates to a high-pressure pump (81), in particular a high-pressure fuel pump in a common-rail injection system, with an inlet (84) which can be connected via an overflow valve (88) with a return (85), in which a return pressure prevails the overflow valve (88) comprises a valve piston (90) which is biased by a valve spring (104) in a closed position.
In order to adjust the pressure in the inlet in a simple manner as accurately as possible in the high-pressure pump, the valve piston (90) of the overflow valve (88) is acted upon by the return pressure such that the overflow valve (88) constantly opposes the pressure during operation of the high-pressure pump (81) Return pressure works.

Description

The invention relates to a high-pressure pump, in particular a high-pressure fuel pump in a common-rail injection system, with an inlet, in which there is an inlet pressure and which can be connected via an overflow valve with a return, in which a return pressure prevails, wherein the overflow valve comprises a valve piston, which is biased by a valve spring in a closed position.

State of the art

From the German patent application DE 10 2013 226 649 A1 a fuel supply device of a fuel injection system of an internal combustion engine with a spill valve is known which has an amount of fuel in a Absteuerleitung and has a spring chamber which is hydraulically in communication with the Absteuerleitung, wherein for hydraulic connection of the spring chamber with the Absteuerleitung a discharge line is provided, the hydraulically a suction side of a Venturi nozzle is connected. From the German patent application DE 10 2015 201 851 A1 an overflow valve for controlling a fuel volume flow in a low-pressure circuit of a fuel injection system is known, with a valve housing and a valve housing displaceable in the valve piston, wherein in the valve housing at least one Absteueröffnung is formed, which lies in a first plane perpendicular to a lateral surface of the valve housing cutting plane , Wherein at least one further Absteueröffnung is formed in a second, perpendicular to the lateral surface of the valve housing and spaced from the first cutting plane second cutting plane. From the German patent application DE 10 2015 202 022 A1 an overflow valve for a high-pressure pump in a fuel injection system of an internal combustion engine is known, comprising a housing and an at least partially accommodated in the housing valve body having a central bore in which for connecting an inlet opening formed in the housing with an outlet opening formed in the valve body, a valve piston axially is displaceably guided, wherein the valve piston is acted upon in the direction of the inlet opening of the spring force of a valve spring, wherein the inlet opening and the outlet opening are each formed on the front side in the housing or in the valve body.

Disclosure of the invention

The object of the invention is, in a high-pressure pump, in particular a high-pressure fuel pump in a common-rail injection system, with an inlet in which there is an inlet pressure and which can be connected via an overflow valve with a return, in which a return pressure prevails, wherein the overflow valve a valve piston which is biased by a valve spring into a closed position to adjust the pressure in the inlet of the high-pressure pump in a simple manner as accurately as possible.

The object is in a high-pressure pump, in particular a high-pressure fuel pump in a common rail injection system, with an inlet in which there is an inlet pressure and which can be connected via an overflow valve with a return, in which a return pressure prevails, wherein the overflow valve comprises a valve piston , which is biased by a valve spring in a closed position, achieved in that the valve piston of the spill valve is acted upon by the return pressure, that the spill valve operates in operation of the high-pressure pump constantly against the return pressure. The performance of a high-pressure pump, in particular a high-pressure diesel pump, is very dependent on the fuel supply, which is represented for example via an electronic fuel pump. Here, a distinction can basically be made between a quantity-controlled and a pressure-controlled electronic fuel pump. In order for the high-pressure pump to deliver a desired high-pressure quantity, a defined pressure should prevail in front of a suction valve of the high-pressure pump. This defined pressure is maintained with the overflow valve in the high pressure pump. The pressure in the inlet in a pump interior of the high-pressure pump should be set as accurately as possible. A particular challenge here lies in a discontinuous delivery principle of the high-pressure pump. The high pressure pump preferably comprises a plurality of radially arranged to a drive shaft pump piston. For example, the pump pistons are driven by cams attached to the drive shaft. Due to the resulting strong dynamics inside the pump, high-frequency pulsations can occur. These pulsations can lead to a greatly reduced piston stroke in conventional overflow valves. With the claimed overflow valve, which works constantly against the return pressure of the high-pressure pump, it is ensured in a simple manner that the overflow valve retains its full function even with high dynamics. As a result, in particular, a desired diversion function of the overflow valve can be maintained without restriction.

A preferred embodiment of the high-pressure pump is characterized in that the valve piston has at one end a closing body, which comes into sealing contact with a valve body in the closed position of the valve body, through which the valve piston is guided and the Has at least one pressure passage connection through which the closing body is constantly acted upon by the inlet pressure on the valve piston during operation of the high-pressure pump. The valve body is designed, for example, as a valve plate. A side facing away from the valve body of the closing body is advantageously facing the return. A radially arranged within a valve seat surface of the closing body is acted upon via the pressure passage connection with the inlet pressure. To illustrate the pressure passage connection, the valve body preferably has a plurality of through holes, via which the closing body is acted upon radially within the valve seat with the inlet pressure. The pressure passage connection advantageously further comprises an annulus radially outward of a portion of the valve body and radially outward of the valve spring of the spill valve. Thus, the valve spring chamber, in which the valve spring is arranged, advantageously part of the pressure passage connection.

A further preferred embodiment of the high-pressure pump is characterized in that the valve piston has at its end remote from the closing body a spring plate on which the valve spring is supported. The valve spring is designed for example as a helical compression spring and is supported by one end on the spring plate. With its other end, the valve spring is advantageously supported on the valve body. By the valve spring, the valve piston is biased in its closed position. The spring plate comprises, for example, a central through hole for the end of the valve body facing away from the closing body. The attachment of the spring plate on the valve piston end is advantageously carried out by a press connection.

A further preferred embodiment of the high-pressure pump is characterized in that the overflow valve, in particular with the valve piston, the valve body and the spring plate, is constructed as a suction valve of the high-pressure pump. About the suction valve, a working fluid of the pump, preferably fuel, sucked into a working space of the high-pressure pump, where the sucked working fluid is then subjected to high pressure. By the same construction of the suction valve and overflow valve, the manufacturing costs for the high-pressure pump can be significantly reduced. On the one hand, this significantly reduces the use of aluminum in the housing of the high-pressure pump. In addition, eliminates a relatively complex processing, as is necessary in conventional overflow valves. As a result, manufacturing costs can be saved.

A further preferred embodiment of the high pressure pump is characterized in that the overflow valve is arranged in a recess which connects the inlet to the return of the high pressure pump. Due to the design and arrangement of the overflow valve, the high-pressure pump can be made significantly more compact. The overflow valve is particularly advantageously mounted axially below a return neck. This allows a common housing processing. This provides the advantage that no additional material and no additional processing are required for the overflow valve. The high pressure pump becomes more compact overall.

Another preferred embodiment of the high-pressure pump is characterized in that the recess is designed as a connecting bore, in which the overflow valve is pressed. Experiments have shown that a large outlet cross section between a plunger chamber and an engine of the high pressure pump has a positive effect on the pulsation and the filling of the high pressure pump. The arrangement of the spill valve in the connecting hole offers more space inside the high-pressure pump, which can be advantageously used for a compensation groove in a plunger bore. According to a further embodiment, the connecting bore is connected to a bearing return, which comprises a lubricating pocket for supporting the drive shaft of the high-pressure pump.

Another preferred embodiment of the high-pressure pump is characterized in that the overflow valve is combined with a filter device. This can effectively prevent contaminants and / or particles from entering sensitive areas of the high-pressure pump. The filter device is arranged, for example, radially outside of through-holes in the valve body. According to a further embodiment, the filter device is associated with the end of the valve piston with the spring plate. However, the filter device may alternatively or additionally be arranged in an inlet bore, which opens into the connection bore, in which the overflow valve is arranged.

The invention further relates to an overflow valve, in particular a valve body, a valve piston and / or a valve spring, for a high pressure pump described above. The overflow valve and the parts mentioned can be traded separately.

In a method for producing a spill valve described above, the above-mentioned object is alternatively or additionally achieved in that a ratio between a controlled during operation of the high pressure pump from the inlet in the return Absteuermenge and the inlet pressure in the inlet via an internal geometry of the valve body in the region Closing body of the overflow valve is adjusted. That shortens synonymous Ratio referred to as the amount / pressure ratio can be arbitrarily adjusted via the internal geometry of the valve body. The internal geometry can be changed cost-neutral, for example by machining, especially in a turning process.

In a method for mounting an overflow valve in a high-pressure pump described above, the above-mentioned object is achieved alternatively or additionally by the following assembly steps. The valve body comprises a central through hole into which the valve piston is inserted. In this case, the valve piston comes with its closing body on the valve body to the plant. The valve spring is then inserted over a valve stem, which starts from the closing body of the valve piston. The spring plate is, for example by a press connection, attached to the end facing away from the closing body of the valve piston, in particular the valve stem. The pre-assembled unit is mounted in a housing of the high-pressure pump in the recess, which connects the inlet to the return of the high-pressure pump. A desired opening pressure of the overflow valve can advantageously be adjusted via a suitable selection of the valve spring and via the press-in depth of the spring plate.

Further advantages, features and details of the invention will become apparent from the following description in which, with reference to the drawings, various embodiments are described in detail.

list of figures

• 1 eine Hochdruckpumpe gemäß dem Stand der Technik im Längsschnitt durch ein Pumpenelement;
• 2 eine perspektivische Schnittdarstellung eines in einer Ausnehmung eines Gehäuses der Hochdruckpumpe angeordneten Überströmventils;
• 3 eine ähnliche Schnittdarstellung wie in 2 aus einer anderen Perspektive;
• 4 eine ähnliche Schnittdarstellung wie in 3 mit einem Lagerrücklauf, der direkt an einen Rücklauf der Hochdruckpumpe angebunden ist; die
• Figuren jeweils eine Längsschnittdarstellung des Überströmventils mit verschie-5 bis 7 denen Innengeometrien eines Ventilkörpers im Bereich eines Schließkörpers des Überströmventils; die
• Figuren kartesische Koordinatendiagramme zu den 5 bis 7, in denen der 8 bis 10 Verlauf eines Menge/Druck-Verhältnisses aufgetragen ist, und
• 11 eine weitere perspektivische Schnittdarstellung des eingebauten Überströmventils zur Veranschaulichung des Einbauortes von Filtereinrichtungen.

Show it:

• 1 a high pressure pump according to the prior art in longitudinal section through a pump element;
• 2 a perspective sectional view of a arranged in a recess of a housing of the high-pressure pump overflow valve;
• 3 a similar sectional view as in 2 from another perspective;
• 4 a similar sectional view as in 3 with a bearing return, which is connected directly to a return of the high-pressure pump; the
• Figures each show a longitudinal sectional view of the spill valve with various 5 to 7 which internal geometries of a valve body in the region of a closing body of the spill valve; the
• Characters Cartesian coordinate diagrams to the 5 to 7 in which the 8 to 10 course of a quantity / pressure ratio is plotted, and
• 11 a further perspective sectional view of the built-in overflow valve to illustrate the installation of filter devices.

Description of the embodiments

In 1 is a section through a high pressure pump 1 for a fuel injection device of an internal combustion engine, as is known from the prior art. The high pressure pump 1 has a multi-part pump housing 2 in which a drive shaft rotatably driven by the internal combustion engine 3 is arranged.

The drive shaft 3 is for example about two in the direction of the axis of rotation 4 the drive shaft 3 rotatably mounted bearing points spaced apart. The bearings can be in different parts of the pump housing 2 can be arranged, for example, a first bearing in a body 5 of the pump housing 2 and a second bearing in one with the body 5 connected flange part 6 be arranged.

In a lying between the bearings area has the drive shaft 3 a cam 7 or an eccentric to its axis of rotation 4 trained section on, with the cam 7 can also be designed as a multiple cam. The high pressure pump 1 has at least one or more in the housing 2 arranged pump elements 8th each with a pump piston 9 on that by the cam 7 the drive shaft 3 in a lifting movement in at least approximately radial direction to the axis of rotation 4 the drive shaft 3 is driven.

In the area of each pump element 8th is one with the main body 5 connected pump housing part 10 provided, which is designed as a cylinder head. The pump housing part 10 has one on an outer side of the body 5 adjacent flange 11 and one through an opening in the body 5 to the drive shaft 3 protruding, at least approximately cylindrical approach 12 with respect to the flange 11 smaller diameter.

The pump piston 9 is in an approach 12 trained cylinder bore 13 in the pump housing part 10 guided tightly displaceable and limited with its the drive shaft 3 opposite end face in the cylinder bore 13 a pump workroom 14 , The cylinder bore 13 can get up in the flange 11 into which then the pump workspace 14 is arranged.

The pump workroom 14 has one in the pump housing 2 extending fuel inlet channel 15 a connection to a fuel inlet, such as a feed pump, on. At the mouth of the fuel inlet duct 15 into the pump workroom 14 is one in the pump work space 14 opening inlet valve 16 arranged. The pump workroom 14 also has one in the pump housing 2 extending fuel drain channel 17 a connection with an outlet on, for example, with a high-pressure accumulator 18 connected is.

With the high-pressure accumulator 18 are one or more arranged on cylinders of the internal combustion engine injectors 19 is connected, is injected through the fuel into the cylinders of the internal combustion engine. At the mouth of the fuel drainage channel 17 into the pump workroom 14 is one out of the pump workroom 14 opening exhaust valve 20 arranged.
During the suction stroke of the pump piston 9 , in which this moves radially inward, the pump working space 14 through the fuel inlet channel 15 with the inlet valve open 16 filled with fuel, with the exhaust valve 20 closed is. During the delivery stroke of the pump piston 9 , in which this moves radially outward, is through the pump piston 9 Fuel under high pressure through the fuel drain channel 17 with the exhaust valve open 20 to the high-pressure accumulator 18 promoted, the intake valve 16 closed is.

Between the pump piston 9 and the cam 7 the drive shaft 3 is a pestle 21 arranged over which the pump piston 9 at least indirectly on the cam 7 the drive shaft 3 supported. The pestle 21 is formed in a hollow cylindrical shape with a round outer cross section and is in a bore 22 of the basic body 5 of the pump housing 2 in the direction of the longitudinal axis 23 of the pump piston 20 slidably guided. The longitudinal axis of the plunger 21 is thus at least substantially identical to the longitudinal axis 23 of the pump piston 9 ,

In the pestle 21 is in the drive shaft 3 facing end a support element 24 used in which a role 25 is rotatably mounted on the cam 7 the drive shaft 3 rolls. The rotation axis 26 the role 25 is at least approximately parallel to the axis of rotation 4 the drive shaft 3 , The support element 24 indicates on its the drive shaft 3 facing side of a depression 27 on, in which the role 25 is rotatably mounted. The support element 24 and the pestle 21 can also be formed in one piece.

At the pestle 21 or on the pump piston 9 grips a preloaded spring 28 , which is designed as a return spring, which is located on the pump housing part 10 supported. By the spring 28 become the pump piston 9 and the pestle 21 to the cam 7 the drive shaft 3 acted upon so that the attachment of the role 25 on the cam 7 also to the drive shaft 3 directed suction stroke of the pump piston 9 and also at high speed of the drive shaft 3 is ensured.

The pump piston 9 can with the pestle 21 be coupled, at least in the direction of its longitudinal axis 23 , Alternatively, the pump piston 9 not even with the pestle 21 be connected, in which case by the return spring 28 the system of the pump piston 9 on the pestle 21 is ensured. It can be provided that the return spring 28 for example, via a spring plate 29 on a diameter enlarged piston foot of the pump piston 9 engages thereby in abutment with a ram 21 is held by the jacket inwardly projecting flange, in turn, in contact with the support element 24 is held, so that the entire composite of pump piston 9 , Pestle 21 and support element 24 with role 25 to the cam 7 the drive shaft 3 is acted upon.

In the direction of the axis of rotation 26 is laterally next to the roll 25 for this one support 30 arranged by which prevents the role 25 in the direction of its axis of rotation 26 from the support element 24 moved out. The role 25 can at their support 30 facing side surfaces convex, for example, at least approximately spherically curved. The side surfaces of the roll 25 facing surface of the support 30 may be formed at least approximately flat or curved. The support 30 can act as one's role 25 be formed surrounding ring or only laterally adjacent to the side surfaces of the roll 25 be arranged.

In the 2 to 4 is a section of a high pressure pump 81 with a housing 82 cut presented in different perspectives. The high pressure pump 81 can be like or similar to the high pressure pump 1 in 1 be executed.

The housing 82 includes a recess 83 in which an overflow valve 88 is arranged. The recess 83 connects an inlet 84 with a return 85 the high pressure pump 81 , The return 85 is, for example via an engine of the high-pressure pump, in communication with a reservoir containing working fluid, in particular fuel.

For example, the inlet is connected to a metering unit which is connected to a suction valve (16in 1 ), also referred to as the inlet valve, the high pressure pump 81 upstream. According to one aspect of the invention, the overflow valve 88 and the suction valve ( 16 in 1 ) executed as equal parts.

The recess 83 is as a connection hole 86 between the inlet 84 and the return 85 executed. In the connection hole 86 is the overflow valve 88 pressed. The overflow valve 88 includes in the connection hole 86 a return pressure chamber 87 , in which the same pressure as in the return 85 prevails. This pressure is also referred to as return pressure.

The overflow valve 88 includes a valve piston 90 , The valve piston 90 has a shaft 91 on top of a closing body 92 emanates. The closing body 92 has a sealing surface 93 on, which represents a valve seat 95 sealing at a sealing edge 94 a valve body 96 is applied.

The valve piston 90 is with his shaft 91 in a guide hole 97 a valve body 96 guided. The valve body 96 is with one in the 2 to 4 upper section in the connection hole 86 pressed. At his in the 2 to 4 lower section, the valve body 96 a total of four through holes 98 . 99 on. The through holes 98 . 99 are part of a print through connection 100 over which the closing body 92 in the valve body 96 radially inside the valve seat 95 is charged with the inlet pressure.

At one of the closing body 92 opposite end 101 of the shaft 91 of the valve piston 90 is a spring plate 102 attached. The spring plate 102 includes a central through hole into which the end 101 of the shaft 91 of the valve piston 90 is pressed.

A valve spring 104 is between a paragraph 105 of the valve body 96 and the spring plate 102 clamped. By the bias of the valve spring 104 becomes the closing body 92 sealing in contact with the valve body 96 held. Then the overflow valve 88 closed.

In 3 you can see that the inflow 84 an inlet hole 108 includes, in which the connecting bore 86 , in which the overflow valve 88 is arranged, opens. The return 85 includes a return bore 110 extending into an enlarged diameter area of the connecting bore 86 empties.

The overflow valve 88 is axially below the return 85 in the case 82 the high pressure pump 81 pressed. This ensures in a simple manner that the spill valve 88 with his the return 85 facing closing body 92 constantly against the return pressure of the high-pressure pump 81 is working. This ensures that the overflow valve 88 even with high dynamics and the occurrence of pressure pulsations retains its full function.

In 4 you can see that a bearing return bore 112 directly with the return 85 above the overflow valve 88 connected is. The bearing return bore 112 connects the return 85 with a lubrication pocket 113 for a storage 115 the drive shaft 114 the high pressure pump 81 ,

In the 5 to 7 is the overflow valve 88 alone with different internal geometries 121 ; 126 ; 131 of the valve body 96 in the area of the valve seat 95 ; 125 ; 130 shown. The opening pressure of the pressure relief valve 88 can about the selection of the valve spring 104 and the Einpresstiefe the spring plate 102 be set. Furthermore, the ratio of a controlled during operation of the high-pressure pump from the inlet in the return Absteuermenge to the inlet pressure in the inlet via the internal geometry 121 ; 126 ; 131 of the valve body 96 in the area of the closing body 92 the overflow valve 88 be adjusted. This ratio is also referred to as the quantity / pressure ratio.

In the 8th to 10 are Cartesian coordinate diagrams of the embodiments of the 5 to 7 shown. On an x-axis, the pressure p is plotted in a suitable printing unit. The pressure p corresponds to the inlet pressure in the inlet of the high-pressure pump. On the y-axis, the quantity Q is plotted in a suitable unit. Quantity Q is the amount of tax deducted.

In the 8th to 10 corresponds to a rather flat section 141 ; 143 ; 146 a warehouse operation. A second section 142 in 8th corresponds to a standard operation of in 5 illustrated overflow valve 88 ,

An in 9 illustrated second section 144 corresponds to an ECO operation. An in 90 third section 145 corresponds to a sports company of the 6 illustrated overflow valve 88 , The different slopes of the volume / pressure ratio in the sections 143 to 145 be through the internal geometry 126 in the area of the valve seat 125 realized.

In 10 has a second section 147 a flatter course. This flatter course 147 is due to the internal geometry 131 in the area of the valve seat 130 in 7 realized.

In 11 is illustrated how and where the spill valve 88 Filtration devices 151 ; 152 ; 153 can be meaningfully assigned. The filter device 151 is radially outside the through holes ( 98 . 99 in the 2 to 7 ) in the connecting bore 86 arranged. The filter device 152 surround the end 101 the stem of the valve piston 90 with the spring plate 102 , In this case, the filter device 152 mostly in the inflow 84 arranged.

The filter device 153 is in the inlet hole 108 arranged. The overflow valve 88 Can be used with or without filter device in all common high pressure pumps, especially diesel pumps.

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• DE 102013226649 A1 [0002]
• DE 102015201851 A1 [0002]
• DE 102015202022 A1 [0002]

Claims (10)

High-pressure pump (1, 81), in particular high-pressure fuel pump in a common-rail injection system, with an inlet (84) in which there is an inlet pressure and via an overflow valve (88) with a return (85) is connectable, in which a return pressure prevails, wherein the overflow valve (88) comprises a valve piston (90) which is biased by a valve spring (104) in a closed position, characterized in that the valve piston (90) of the overflow valve (88) is acted upon by the return pressure, that the overflow valve (88) constantly operates against the return pressure during operation of the high-pressure pump (1; 81). High pressure pump after Claim 1 , characterized in that the valve piston (90) at one end has a closing body (92) which in the closed position of the valve body sealingly abuts a valve body (96) through which the valve piston (90) is guided and the at least one Druckdurchgangsverbindung (100), via which the closing body on the valve piston (90) during operation of the high-pressure pump (81) is constantly acted upon by the inlet pressure. High pressure pump after Claim 2 , characterized in that the valve piston (90) at its end facing away from the closing body (92) has a spring plate (102) on which the valve spring (104) is supported. High-pressure pump according to one of the preceding claims, in particular according to Claim 3 , characterized in that the overflow valve (88), in particular with the valve piston (90), the valve body (96) and the spring plate (102), is constructed as a suction valve (16) of the high-pressure pump (81). High pressure pump according to one of the Claims 2 to 4 , characterized in that the overflow valve (88) in a recess (83) is arranged, which connects the inlet (84) with the return (85) of the high-pressure pump (81). High pressure pump after Claim 5 , characterized in that the recess (83) is designed as a connecting bore (86) into which the overflow valve (88) is pressed. High pressure pump after Claim 6 , characterized in that the overflow valve (88) is combined with a filter device (151; 152; 153). Overflow valve (88), in particular valve body (96), valve piston (90) and / or valve spring (104), for a high-pressure pump (81) according to one of Claims 2 to 7 , Method for producing an overflow valve (88) according to Claim 8 , characterized in that a ratio between a controlled during operation of the high pressure pump (81) from the inlet (4) in the return (85) Absteuermenge and the inlet pressure in the inlet (84) via an internal geometry (121, 126, 131) of the valve body (96) in the region of the closing body (92) of the overflow valve (88) is adjusted. Method for mounting an overflow valve (88) in a high pressure pump (81) according to one of Claims 2 to 7 characterized by the following assembly steps: - the valve piston (90) is inserted into the valve body (96); - The valve spring (104) is inserted over the valve piston (90); - The spring plate (102) is attached to the valve piston (90); - The preassembled unit is mounted in the high-pressure pump (81) in the recess (83) which connects the inlet (84) with the return (85) of the high-pressure pump (81).

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