DE102017217497A1 - High pressure pump for a fuel injection system - Google Patents

Abstract

The invention relates to a high-pressure pump for a fuel injection system, in particular for a common-rail injection system, comprising a pump cylinder head (1), in which a suction valve (2) is integrated, wherein the suction valve (2) has a hubbeweglichen cooperating with a valve seat (3) Valve tappet (4) which is acted upon in the direction of the valve seat (3) by the spring force of a closing spring (5), wherein the closing spring (5) on the one hand to a valve plate (4) connected to the spring plate (6), on the other hand to a paragraph (7) of the pump cylinder head (1) is supported, which cooperates with the spring plate (6) stop forming. According to the invention, at least one annular abutment surface (8, 9) formed on the spring plate (6) and / or on the shoulder (7) has an arched, stepped and / or grooved contour.

Description

The invention relates to a high pressure pump for a fuel injection system, in particular for a common rail injection system, having the features of the preamble of claim 1. The high pressure pump comprises a pump cylinder head, in which a suction valve is integrated.

State of the art

A high pressure pump of the type mentioned above is an example of the published patent application DE 10 2015 212 387 A1 out. The high-pressure pump has a high-pressure element space which can be filled with fuel via a suction valve. For this purpose, the suction valve is integrated into a housing part of the high-pressure pump, which also forms the high-pressure element space. Further, the housing part forms a valve seat for a liftable valve closing element of the suction valve, which has the shape of a valve stem and opens into the element space inside. In the opening direction of the plunger is acted upon by the spring force of a spring supported on an armature, which holds the suction valve open when energized electromagnet. To close the suction valve, the electromagnet is energized, so that a magnetic field is built up whose magnetic force acts on the armature. The armature moves against the spring force of the armature spring in the direction of the electromagnet. In this case, the armature releases from the valve stem, so that a smaller supported on the valve stem spring is able to pull the valve stem into the valve seat. The suction valve closes. For reopening the energization of the electromagnet is terminated, so that the armature is returned to its original position via the spring force of the armature spring. The armature strikes the valve lifter and lifts it out of the valve seat. The suction valve opens.

To ensure optimum filling of the high-pressure pump, it must be ensured that the suction valve closes without delay. There may be a delay, in particular due to hydraulic and / or magnetic adhesive effects between components that interact stop-forming. The present invention is therefore based on the object to minimize such adhesive effects.

To solve the problem, the high-pressure pump with the features of claim 1 is proposed. Advantageous developments of the invention can be found in the dependent claims.

Disclosure of the invention

The high-pressure pump proposed for a fuel injection system, in particular for a common rail injection system, comprises a pump cylinder head in which a suction valve is integrated. The suction valve has a cooperating with a valve seat liftable valve tappet, which is acted upon in the direction of the valve seat by the spring force of a closing spring. The closing spring is supported on the one hand on a spring plate connected to the valve stem, on the other hand on a shoulder of the pump cylinder head, which cooperates with the spring plate stop forming. According to the invention, at least one annular abutment surface formed on the spring plate and / or on the shoulder has a curved, stepped and / or grooved contour.

Characterized in that at least one stop surface has a curved, stepped and / or grooved contour, the contact area between the spring plate and the shoulder of the pump cylinder head decreases. At the same time the risk is counteracted that it comes to hydraulic adhesive effects in the attack area. This means that the suction valve closes without delay, so that a reduction in the maximum delivery of the high-pressure pump is not to be feared.

Due to the lack of or at least to a minimum reduced hydraulic adhesion of the spring plate on the shoulder of the pump cylinder head, a reduction of the switching times can also be achieved.

The curved, stepped and / or grooved stop surface may be formed on the spring plate or on the shoulder of the pump cylinder head. In addition, the spring plate and the paragraph may each have a curved, stepped and / or grooved stop surface.

Preferably, the at least one annular stop surface formed on the spring plate and / or on the shoulder has a convexly curved contour. A convex curved contour facilitates the displacement of fuel from the stop area when opening the suction valve. When closing the convex curved contour promotes a flow of fuel, so that hydraulic adhesive effects can not occur. If both stop surfaces each have a convexly curved contour, they are preferably designed mirror-inverted, so that touch the spring plate and the heel only in the region of an annular line. The annular line can be carried out continuously or have interruptions. The latter also applies if only one stop surface has a convexly curved contour.

Furthermore, it is proposed that the curved, stepped and / or grooved contour of the at least one of the spring plate and / or the paragraph trained annular abutment surface from radially inside to radially outside drops. This means that when striking the spring plate at the shoulder of the pump cylinder head radially inside with respect to the common contact area no fuel-filled area remains, but the fuel is completely displaced. This also helps to minimize the risk of hydraulic sticking of the spring plate to the heel.

The falling off of the stop surface from radially inward to radially outward can take place via a curved and / or stepped contour.

Preferably, at least one step and / or at least one groove is formed in the abutment surface. If a step is provided, this is preferably formed circumferentially, so that a stop surface is provided with a reduced dimension in the radial direction. If a groove is provided, this is preferably also performed circumferentially, so that the stop surface is reduced by the width of the groove. Alternatively or additionally, a plurality of grooves may be provided which preferably extend radially and are furthermore preferably arranged at the same angular distance from each other. By radially extending grooves, the annular abutment surface is divided into individual segments and reduced overall. In addition, radially extending grooves facilitate the flow of fuel when the spring plate moves when closing the suction valve from the shoulder of the pump cylinder head. In this way, a fast closing of the suction valve is promoted.

Preferably, the step and / or the groove has a depth of at least 10 microns. If the depth is lower, the step or the groove can not counteract hydraulic adhesive effects. Particularly preferably, the step and / or the groove has a depth of at least 50 microns to 200 microns in order to ensure the fastest possible closing of the suction valve.

Furthermore, it is proposed that the spring plate surrounds the valve stem in sections. This arrangement facilitates the assembly of the suction valve, since the spring plate can be connected to the valve stem via a simple press or screw connection. Preferably, therefore, the spring plate is pressed or screwed onto the valve stem.

The suction valve can be designed both as a mechanical suction valve, as well as electromagnetically actuated suction valve. If the latter is the case, a magnet assembly for the electromagnetic actuation of the suction valve is provided, wherein preferably the magnet assembly comprises an annular magnet coil, a pole core and a magnetic sleeve. The magnet assembly can be attached to the pump as a preassembled unit. For example, a radially outwardly extending collar for supporting a union nut can be formed on the magnet sleeve, which can be screwed onto a collar-shaped section of the pump cylinder head.

The magnet assembly preferably cooperates with an armature, which is acted upon in the direction of the valve stem by the spring force of an armature spring. The spring force of the armature spring is greater than the spring force of the spring plate supported on the closing spring, so that the spring plate is pressed by the armature spring against the shoulder of the pump cylinder head when the solenoid is de-energized. The suction valve is thus designed as a normally open valve. To close the valve, the magnetic coil is energized, so that a magnetic field is built up whose magnetic force moves the armature in the direction of the pole core. In this case, the armature releases from the valve stem and the closing spring supported on the spring plate is able to pull the valve stem into the valve seat, so that the suction valve closes.

• 1 einen schematischen Längsschnitt durch eine erfindungsgemäße Hochdruckpumpe im Bereich eines in die Hochdruckpumpe integrierten elektromagnetisch betätigbaren Saugventils,
• 2 einen vergrößerten Ausschnitt der 1 im Bereich eines Hubanschlags zwischen einem Federteller des Saugventils und einem Pumpenzylinderkopf der Hochdruckpumpe,
• 3-5 jeweils eine modifizierte Ausführungsform des Hubanschlags der 2.

Preferred embodiments of the invention are explained below with reference to the accompanying drawings. These show:

• 1 3 shows a schematic longitudinal section through a high-pressure pump according to the invention in the region of an electromagnetically actuated suction valve integrated in the high-pressure pump,
• 2 an enlarged section of the 1 in the area of a stroke stop between a spring plate of the suction valve and a pump cylinder head of the high pressure pump,
• 3-5 in each case a modified embodiment of the stroke stop the 2 ,

Detailed description of the drawings

The in the 1 schematically illustrated high-pressure pump comprises an electromagnetically actuated suction valve 2 for filling an element space 24 the high-pressure pump with fuel. The element space 24 is in a cylinder bore 25 a pump cylinder head 1 formed in which a pump piston 26 for limiting the element space 24 is included. With a suction stroke of the pump piston 26 will fuel through the suction valve 2 in the element space 24 sucked and compressed at a delivery stroke. The compressed fuel is then passed through a high pressure valve 27 from the element space 24 dissipated.

The pump cylinder head 1 the high-pressure pump forms a valve seat 3 for a liftable valve lifter 4 of the suction valve 2 out into the element space 24 opens into it. Andernends is on the valve lifter 4 a spring plate 6 for supporting a closing spring 5 pressed on, further on a paragraph 7 the pump cylinder head 1 is supported. At the same time acts on the valve lifter 4 the spring force of an anchor spring 17 whose spring force is greater than that of the closing spring 5 is, so the anchor spring 17 the suction valve 2 keeps open. From an annular low-pressure chamber 23 can then fuel into the element space 24 to stream. To close the suction valve 2 becomes a magnetic coil 13 a magnetic assembly attached to the high pressure pump 12 energized, so that a magnetic field is built up whose magnetic force is an anchor 16 against the spring force of the armature spring 17 in the direction of a pole core 14 draws. This releases the anchor 16 from the valve lifter 4 so that the closing spring 5 the valve lifter 4 in the valve seat 3 to draw. To reopen the suction valve 2 is the energization of the solenoid 13 finished, leaving the anchor spring 17 the anchor 16 returns to its original position, the anchor 16 on the valve lifter 4 strikes and this from the valve seat 3 lifts.

The magnet assembly 12 is by means of a union nut 19 on a collar section 20 the pump cylinder head 1 attached, this purpose an external thread 21 having. Andernend is the union nut 19 on an outer peripheral side collar of a magnetic sleeve 15 the magnet assembly 12 supported. The magnet sleeve 15 in turn stands on a valve body 18 on that in the collar section 20 the pump cylinder head 1 is used. Further, the magnet assembly has 12 a plastic extrusion 22 which has a sealing and an insulating function.

To close the suction valve 2 hydraulic adhesive effects between the spring plate 6 and the paragraph 7 de pump cylinder head 1 counteract, have the spring plate 6 and the paragraph 7 one stop surface each 8th . 9 on, which is crowned. For this purpose, the stop surfaces 8th . 9 each have a convex curved contour (see 2 ). Due to the convex curved contour, the contact area between the spring plate 6 and the paragraph 7 reduced to a minimum. The contour also drops from radially inward to radially outward, so that when closing the suction valve, the fuel slightly below the spring plate 6 can flow to ensure a fast closing.

In the 3 is a modification of the embodiment of the 1 and 2 shown. The convex contours of the stop surfaces 8th . 9 fall off both radially outward and radially inward. The subsequent flow of fuel when closing the suction valve 2 remains over the convex contours of the stop surfaces 8th . 9 guaranteed.

Another modification shows the 4 , Here is the spring plate 6 trained stop surface 8th by a circumferential step 10 reduced, which has a depth T. The contact area is thus limited to the radially inner region of the stop surface 8th , The stop surface 9 of the paragraph 7 can be executed in this case.

In the 5 , which can be seen a further modification, has the stop surface 8th of the spring plate 6 a circumferential groove 11 on to the contact area with the paragraph 7 the pump cylinder head 1 to reduce. The stop surface 9 of the paragraph 7 again can be executed.

The invention is not limited to the illustrated embodiments, but includes further modifications as the step 10 and / or the groove 11 also in the stop area 9 of the paragraph 7 can be trained or can. Alternatively or additionally, radially extending grooves 11 be provided (not shown), which the stop surface 8th and / or the stop surface 9 divide into segments. In addition, arched, stepped and / or grooved contours can be combined.

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 102015212387 A1 [0002]

Claims (9)

High-pressure pump for a fuel injection system, in particular for a common rail injection system, comprising a pump cylinder head (1), in which a suction valve (2) is integrated, wherein the suction valve (2) has a liftable valve tappet (4) cooperating with a valve seat (3). which is acted upon in the direction of the valve seat (3) by the spring force of a closing spring (5), the closing spring (5) on the one hand on a spring plate (6) connected to the valve tappet (4), on the other hand on a shoulder (7) of Pump cylinder head (1) is supported, which cooperates with the spring plate (6) stop forming, characterized in that at least one on the spring plate (6) and / or on the shoulder (7) formed annular abutment surface (8, 9) a curved, stepped and / or grooved contour. High pressure pump after Claim 1 , characterized in that the at least one of the spring plate (6) and / or on the shoulder (7) formed annular abutment surface (8, 9) has a convexly curved contour. High pressure pump after Claim 1 or 2 , characterized in that the curved, stepped and / or grooved contour of the at least one on the spring plate (6) and / or on the shoulder (7) formed annular abutment surface (8, 9) drops from radially inward to radially outward. High-pressure pump according to one of the preceding claims, characterized in that in the stop surface (8, 9) at least one step (10) and / or at least one groove (11) is or are formed, which is preferably formed circumferentially or are. High pressure pump after Claim 4 , characterized in that in the stop surface (8, 9) a plurality of radially extending grooves (11) are formed, which are preferably arranged at the same angular distance from each other. High pressure pump after Claim 4 or 5 , characterized in that the step (10) and / or the groove (11) has a depth (T) of at least 10 microns, further preferably a depth (T) of at least 50 microns to 200 microns or have. High-pressure pump according to one of the preceding claims, characterized in that the spring plate (6) surrounds the valve tappet (4) in sections, wherein preferably the spring plate (6) is pressed or screwed onto the valve tappet (4). High-pressure pump according to one of the preceding claims, characterized in that a magnet assembly (12) for the electromagnetic actuation of the suction valve (2) is provided, wherein preferably the magnet assembly (12) comprises an annular magnet coil (13), a pole core (14) and a magnetic sleeve ( 15). High pressure pump after Claim 8 , characterized in that the magnet assembly (12) cooperates with an armature (16) which is acted upon in the direction of the valve stem (3) by the spring force of an armature spring (17).

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