DE102017207721A1 - Metering unit, high pressure pump and high pressure injection system - Google Patents

Abstract

A metering unit (37), a high-pressure pump (1) and a high-pressure injection system (36) are each proposed with a metering unit (37) which enables damping of pressure pulsations. The metering unit (37) comprises an electromagnet (17), an electromagnet (17) movable armature (14), a movable between a closed position and an open position valve piston (15), wherein the valve piston (15) in mechanical operative connection with the armature (14) is positioned so that the valve piston (15) can be moved in a first direction by means of the magnetic force applied by the electromagnet (17) to the armature (14); a first elastic valve element (18), in particular a first valve spring which applies a force to the valve piston (15) so that the valve piston (15) is movable in a second direction with the first elastic valve element (18) and a second elastic valve element (100), in particular a second valve spring, between the valve piston (15) and the armature (14) is arranged.

Description

State of the art

Disclosure of the invention

Metering unit, high pressure pump and high pressure injection system

The invention relates to a metering unit, a high-pressure pump and a high-pressure injection system according to the preamble of the independent claims.

State of the art

From the publication WO 2015/043635 A1 is a metering unit, in particular for a high-pressure pump, known comprising an electromagnet, a movable armature of the electromagnet, a movable between a closed position and an open position valve piston, wherein the valve piston is in mechanical operative connection with the armature, so that by means of the electromagnet magnetic force applied to the armature of the valve piston is movable in a first direction, and an elastic valve element, in particular a valve spring, which applies a force to the valve piston, so that the valve piston is movable in a second direction with the elastic valve element.

Disclosure of the invention

The metering unit according to the invention, the high-pressure pump according to the invention and the high-pressure injection system according to the invention with the features of the independent claims have the advantage that the metering unit an electromagnet, a movable armature by the electromagnet, a movable between a closed position and an open position valve piston, wherein the valve piston in mechanical operative connection is with the armature, so that by means of the force applied by the electromagnet to the armature magnetic force of the valve piston is movable in a first direction, a first elastic valve element, in particular a first valve spring, which applies a force to the valve piston, so that with the elastic valve element the valve piston is movable in a second direction, and a second elastic valve element, in particular a second valve spring, which is arranged between the valve piston and the armature comprises. The second elastic valve member and its arrangement between the valve piston and the armature causes pressure oscillations of the metered fuel in a space downstream of the valve piston, which are due to the opening or closing of a suction valve of the high-pressure pump, to be damped. Thus it is avoided that the valve piston gets into vibration by the pressure oscillations of the metered fuel or such vibrations of the valve piston are damped. The position of the valve piston is thus stabilized. This ensures that the set metering rate is maintained. In addition, tilting of the valve piston is prevented due to the pressure oscillations.

The measures listed in the dependent claims advantageous refinements and improvements of the metering unit according to the invention are possible.

It is advantageous if the second elastic valve element has a linear spring characteristic. In this way, the pressure oscillations of the metered fuel downstream of the valve piston are damped in proportion to their intensity.

But it is also advantageous if the second elastic valve element has a progressive spring characteristic. In this way, stronger pressure oscillations can be disproportionately damped, whereby they are attenuated correspondingly stronger.

It is suitable for the metering unit according to the invention if the valve piston has at least one radial inlet opening. This allows a simple construction of the metering unit.

Furthermore, it is advantageous if the valve piston has an axial outlet opening at its end facing away from the armature. In such a simple and inexpensive construction of the valve piston, which also allows a simple and inexpensive construction of the metering unit, the damping described has a particularly effective, since the valve piston is directly exposed to pressure fluctuations

A simple mechanical operative connection between valve piston and armature results when a plunger is provided, which transmits a movement of the armature to the valve piston.

It is also particularly advantageous if the valve piston is cylindrical and guided in a sleeve-shaped housing, which is closed at its end facing the armature by a lid and that the lid comprises an opening for guiding the plunger. This allows easy accommodation of the second elastic valve element.

Such a simple arrangement of the second elastic valve element can be achieved if the second elastic valve element on the one hand on a surface facing the armature the valve piston and on the other hand supported on the lid.

It is also advantageous if, downstream of the valve piston, a collector is provided for connecting at least one suction valve. In this way, the supply of the metered fuel from the metering unit to the at least one suction valve is realized in a particularly simple and inexpensive manner, the associated problem of the pressure oscillations of the metered fuel being effectively avoided or reduced.

• 1 einen Querschnitt einer Hochdruckpumpe,
• 2 einen Schnitt A-A gemäß 1 einer Laufrolle mit Rollenschuh und einer Antriebswelle,
• 3 eine stark schematisierte Ansicht eines Hochdruckeinspritzsystems,
• 4 einen Längsschnitt einer Zumesseinheit gemäß einem ersten Ausführungsbeispiel und
• 5 einen Längsschnitt der Zumesseinheit gemäß einem zweiten Ausführungsbeispiel.

A preferred embodiment of the invention will be explained in more detail with reference to the accompanying drawings. These show:

• 1 a cross section of a high pressure pump,
• 2 a section AA according to 1 a roller with roller shoe and a drive shaft,
• 3 a highly schematic view of a high-pressure injection system,
• 4 a longitudinal section of a metering unit according to a first embodiment and
• 5 a longitudinal section of the metering unit according to a second embodiment.

Embodiments of the invention

In 1 is a cross section of a high pressure pump 1 for a high-pressure injection system 36 shown. The high pressure pump 1 serves to fuel, z. As gasoline or diesel, to an internal combustion engine 39 to promote under high pressure. The from the high pressure pump 1 producible pressure 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 on that around an axis of rotation 26 performs a rotational movement. The rotation axis 26 which also has a longitudinal axis 26 the drive shaft 2 represents lies in the plane of 1 and is perpendicular to the plane of 2 , The piston 5 is in a cylinder 6 as a piston guide 7 stored by a housing 8th is formed. A workroom 29 is from the cylinder 6 , the housing 8th and the piston 5 limited. In the workroom 29 opens an inlet channel 22 with an inlet valve 19 and an exhaust duct 24 with an exhaust valve 20 , Through the inlet channel 22 with an inlet opening 21 the fuel flows into the workspace 29 in and through the outlet channel 24 with an outlet opening 23 the fuel flows under high pressure from the working space 29 out again. The inlet valve 19 , z. B. a check valve is designed to the effect that only fuel in the working space 29 can flow in and the exhaust valve 20 , z. B. a check valve, is designed such that only fuel from the working space 29 can flow out. The volume of the work space 29 is due to an oscillating stroke movement of the piston 5 changed. The piston 5 is supported indirectly on the drive shaft 2 from. At the end of the piston 5 or pump piston 5 is a roller shoe 9 with a roller 10 attached. The roller 10 can perform a rotational movement, the axis of rotation 25 in the drawing plane according to 1 lies and perpendicular to the plane of 2 stands. The drive shaft 2 with the at least one cam 3 has a wave rolling surface 4 and the roller 10 a roller rolling surface 11 on.

The roller tread 11 the roller 10 rolls on a contact surface 12 on the wave rolling surface 4 the drive shaft 2 with the two cams 3 from. The roller shoe 9 is in one of the housing 8th formed roller shoe storage stored as a plain bearing. A feather 27 or spiral spring 27 as an elastic element 28 between the case 8th and the roller shoe 9 is clamped, brings on the roller shoe 9 a compressive force on, leaving the roller rolling surface 11 the roller 10 in constant contact with the shaft rolling surface 4 the drive shaft 2 stands. The roller shoe 9 and the piston 5 thus jointly carry out an oscillating lifting movement.

In 3 is a highly schematic representation of the high-pressure injection system 36 for a motor vehicle (not shown) shown with a high-pressure rail 30 or a fuel rail 31 , From the high-pressure rail 30 the fuel by means of valves (not shown) in the combustion chamber of the internal combustion engine 39 injected. A prefeed pump 35 Promotes fuel from a fuel tank 32 through a fuel line 33 to the high pressure pump 1 according to the above embodiment. The high pressure pump 1 and the prefeed pump 35 be doing of the drive shaft 2 driven. The drive shaft 2 is with a crankshaft of the internal combustion engine 39 coupled. The high pressure rail 30 serves - as already described - to the fuel in the combustion chamber of the internal combustion engine 39 inject. The from the pre-feed pump 35 Promoted fuel is through the fuel line 33 to the high pressure pump 1 directed. The from the high pressure pump 1 Unnecessary fuel is thereby through a fuel return line 34 back in the fuel tank 32 returned. A suction-side metering unit 37 controls and / or regulates the high-pressure pump 1 supplied quantity of fuel, so that in a further embodiment of the fuel return line 34 can be omitted (not shown).

In 4 is a longitudinal section of the metering unit 37 according to a first embodiment shown. The metering unit 37 as a solenoid valve has a metering 54 or a magnetic sleeve 54 inside, inside of which is an electromagnet 17 or a coil 17 is arranged. Inside the electromagnet 17 is a pole tube 44 positioned and inside the pole tube 44 is an anchor 14 arranged. The anchor 14 is in the direction of a longitudinal axis 64 movable on the pole tube 44 stored and at a lower end of the anchor 14 lies a pestle 47 on. The pole tube 44 made of metal is on the top of a first lid 55 closed from metal and the first lid 55 is by means of a welding ring (not shown) with the pole tube 44 connected. This is the anchor 14 in the in 4 position not shown directly on the first cover 55 on, but between the first lid 55 and the anchor 14 is a residual air disc 56 arranged. The residual air disc 56 has the task of providing a sufficient residual air gap for that of the electromagnet 17 provided magnetic circuit. The magnet sleeve 54 is up with an upper flange ring 57 and below with a lower flange ring 58 with the pole tube 44 connected by a press fit.

The pole tube 44 has below the inside a web ring 45 on, which forms a second cover, and through an opening on the web ring 45 is the pestle 47 guided. Furthermore, the pole tube 44 at the lower end of a disc-shaped opening, within which an upper end of a valve piston bearing part 38 is attached by means of a press fit. The valve piston bearing part 38 , For example, made of thermoplastic material, has a bearing bore 40 on and within the bearing bore 40 is a guide sleeve 50 arranged or attached from metal. The valve piston bearing part 38 and the guide sleeve 50 form such a sleeve-shaped housing in which the valve piston 15 is guided. The valve piston 15 is in this case cylindrical. An inside guide surface or inside of the guide sleeve 50 thereby forms a storage 41 as sliding bearing 42 for a valve piston 15 made of metal, z. Steel. This causes the valve piston 15 made of metal on the guide sleeve 50 also made of metal. The guide sleeve 50 and the valve piston 15 are in the field of plain bearings 42 For example, provided with a coating as Nitrocarbonierung to the friction between the guide sleeve 50 and the valve piston 15 reduce and also a longer life of the sliding bearing 42 on the guide sleeve 50 to ensure.

At the bottom end of the guide sleeve 50 is a spring adjusting piece 59 on the radial inside of the guide sleeve 50 attached. With the spring adjusting piece 59 can the bias of a first elastic valve element 18 be set. On the spring adjusting piece 59 lies the first elastic valve element 18 , formed in the present example as a first valve spring, bottom side and the first valve spring 18 lies on the top of the valve piston 15 on. The first valve spring 18 is constantly biased and in 4 is an open position of the metering unit 37 shown, ie an open position of the valve piston 15 , At the valve piston bearing part 38 as well as on the guide sleeve 50 is an inlet opening 52 for introducing the fuel available. In this case, the valve piston 15 a control channel 51 on and in the in 4 illustrated opening position of the valve piston 15 The control channel is aligned 51 via a radial inlet opening 120 of the valve piston 15 with the inlet opening 52 the valve piston bearing part 38 , so that thereby the fuel through the valve piston 15 and the valve piston bearing part 38 can flow.

When energizing the coil 17 or the electromagnet 17 is generated by this a magnetic field. It is in the present example to ensure a compact design of the metering unit 37 the anchor 14 partially made of iron inside the electromagnet 17 arranged. To move during energization of the electromagnet 17 of the anchor 14 To allow down, is a diverting of the electromagnet 17 generated magnetic field required. For this purpose, the pole tube 44 the bridge ring 45 and on the outside an annular groove 46 on, so that the web ring 45 and the ring groove 46 a means 43 to divert the magnetic field. When energizing the electromagnet 17 acts on the anchor 14 a downward magnetic force, thereby leaving the armature 14 on the pestle 47 a downward pressure force is applied and from the plunger 47 this pressure force on the valve piston 15 is transmitted, so that thereby the valve piston 15 opposite to that of the first valve spring 18 on the anchor 14 applied compressive force in the direction of the first direction 49 is moved down to a closed position, not shown, of the valve piston 15 , In the closed position of the valve piston 15 is from the valve piston 15 the inlet opening 52 the valve piston bearing part 38 closed, so that thereby the metering unit 37 allows no flow of fuel. When switching off the energization of the electromagnet 17 gets on the anchor 14 no magnetic force applied, thereby characterized by means of the first valve spring 18 on the valve piston 15 applied pressure force of the valve piston 15 and with it the pestle 47 and the anchor 14 in the direction of a second direction 48 upwards into the open position of the valve piston 15 can be moved.

According to the invention is between the anchor 14 and the valve piston 15 a second elastic valve element 100 arranged. The second elastic valve element 100 is in this example also designed as a valve spring and is referred to below as the second valve spring. More precisely, the second valve spring is supported 100 on the one hand at an anchor 14 or the web ring 45 facing surface 105 of the valve piston 15 and on the other hand on the web ring 45 from. The second valve spring 100 has a linear spring characteristic. Alternatively, the second valve spring 100 a progressive spring characteristic.

In spring setting piece 59 is centric axially an outlet opening 53 arranged with an axial outlet opening 125 the valve piston corresponds and through the the via the inlet opening 52 the valve piston bearing part 38 and the inlet opening 120 of the valve piston 15 introduced fuel in an example tubular collector 110 in continuation of the valve piston bearing part 38 downstream of the valve piston bearing part 38 exit. The collector 110 has at least one connection shown schematically in the form of an outlet 115 for a suction valve, not shown on.

When opening or closing the respective to the collector 110 connected suction valve pressure fluctuations of the fuel located in the collector are generated, which affect the valve piston 15 transfer. The so on the valve piston 15 transmitted pressure fluctuations are from the second valve spring 100 attenuated. In the case of a linear spring characteristic, pressure fluctuations with greater intensity are damped correspondingly more proportionally. When using a second valve spring with progressive spring constant pressure fluctuations are attenuated disproportionately with greater intensity.

By damping the pressure fluctuations can be corresponding oscillations of the Ventilkobens 15 largely avoid and a stable position of the valve piston 15 according to the respective control of the coil 17 or the electromagnet 17 to adjust. This allows the desired metering rate for the fuel in the form of the corresponding complete or partial overlap of the opening cross-sections of the inlet opening 52 the valve piston bearing part 38 and the inlet opening 120 of the valve piston 15 stable. Furthermore, with the help of the second valve spring 100 a tilting of the valve piston 15 due to the pressure fluctuations effectively avoided.

The metering unit 37 ie the valve piston bearing part 38 , For example, partially within a non-illustrated recess of the housing 8th the high pressure pump 1 be arranged. To ensure adequate sealing of the metering unit 37 To ensure this is with an upper first O-ring seal 60 and a second lower O-ring seal 61 Mistake. The second O-ring seal 61 is inside an annular groove 62 the valve piston bearing part 38 arranged and serves to seal the metering unit 37 with regard to the high pressure pump 1 and the first O-ring seal 60 serves to seal the metering unit 37 outward.

Alternatively, the metering unit 37 also outside and separately from the high pressure pump 1 be arranged.

In 5 is a second embodiment of the metering unit 37 shown. In 5 like reference characters designate like elements as in FIG 4 , In the following, essentially only the differences from the first embodiment of the metering unit 37 according to 4 described. The pole tube 44 does not have a web ring 45 on and on the valve piston bearing part 38 is not a guide sleeve 50 arranged of metal. In this case, the valve piston bearing part forms 38 only the sleeve-shaped housing for guiding the cylindrical valve piston 15 , Further, the valve piston 15 not made of metal as in the first embodiment, but made of plastic. As a means 43 for deflecting or diverting the magnetic field thus has the metering unit 37 only over the pole tube 44 and the ring groove 46 , Due to the design of the valve piston 15 made of plastic, this can directly on the valve piston bearing part 38 also be stored in plastic. This can save the cost of manufacturing the metering unit 37 be further reduced because of the lower mass of the valve piston 15 the electromagnet 17 can be made smaller due to the lower mass to be moved of the valve piston 15 ,

As in the second embodiment according to 5 the bridge ring 45 missing, can be for the anchor-side support of the second valve spring 100 the second lid provided separately and, for example, as a support on the armature end of the valve piston bearing part 38 in the Pohlrohr 44 be pressed. The second lid carries in 5 the reference number 130 and is preferably formed of plastic.

Overall, are considered with the metering unit according to the invention 37 As a solenoid valve associated significant benefits. The valve piston bearing part 38 consists at least partially of plastic, in particular thermoplastic, so that thereby the valve piston bearing part 38 can be inexpensively manufactured by injection molding of thermoplastic material. This allows the weight of the metering unit 37 reduces and further advantageously the manufacturing cost of the metering unit 37 be reduced because the valve piston bearing part 38 not in a complex manner of metal, z. B. by primary molding and preferably a machining, must be made. The valve piston bearing part serves this purpose 38 in the Essentially not for diverting the from the electromagnet 17 generated magnetic field, but this is by means 43 outside the valve piston bearing part 38 executed.

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

• WO 2015/043635 A1 [0002]

Claims (11)

Metering unit (37), in particular for a high-pressure pump (1), comprising - an electromagnet (17), - an armature (14) movable by the electromagnet (17), - a valve piston (15) movable between a closed position and an open position, wherein the Valve piston (15) is in mechanical operative connection with the armature (14), so that by means of the magnetic force applied by the electromagnet (17) to the armature (14) magnetic force of the valve piston (15) is movable in a first direction, - a first elastic valve element (18), in particular a first valve spring, which applies a force to the valve piston (15), so that with the first elastic valve element (18) the valve piston (15) is movable in a second direction, characterized in that - a second elastic Valve element (100), in particular a second valve spring, between the valve piston (15) and the armature (14) is arranged. Metering unit (37) according to Claim 1 , characterized in that the second elastic valve member (100) has a linear spring characteristic. Metering unit (37) according to Claim 1 , characterized in that the second elastic valve element (100) has a progressive spring characteristic. The metering unit (37) according to any one of the preceding claims, characterized in that the valve piston (15) has at least one radial inlet opening (120). The metering unit (37) according to any one of the preceding claims, characterized in that the valve piston (15) has an axial outlet opening (125) at its end facing away from the armature (14). A metering unit (37) according to any one of the preceding claims, characterized in that a plunger (47) is provided, which transmits a movement of the armature (14) on the valve piston (15). Metering unit (37) according to Claim 6 , characterized in that the valve piston (15) has a cylindrical shape and is guided in a sleeve-shaped housing (38, 50) which is closed at its end facing the armature (14) by a cover (45, 130) and in that the cover ( 45, 130) comprises an opening (135) for guiding the plunger (47). Metering unit (37) according to Claim 7 , characterized in that the second elastic valve element (100) on the one hand on a said armature (14) facing surface (105) of the valve piston (15) and on the other hand on the lid (45, 130) is supported. Metering unit (37) according to one of the preceding claims, characterized in that downstream of the valve piston (15) a collector (110) is provided for connecting at least one suction valve. High-pressure pump (1) for conveying a fluid, in particular fuel, comprising a metering unit (37) according to one of the preceding claims. High-pressure injection system (36) for an internal combustion engine (39), comprising - a high-pressure pump (1), - a metering unit (37) according to one of Claims 1 to 9 , - A prefeed pump (35) for conveying a fuel from a fuel tank (32) via the metering unit (37) to the high-pressure pump (1).

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