DE102009001433A1 - Suction valve for a high-pressure fuel pump - Google Patents

Abstract

A suction valve (51) with a filter element (81) and a high-pressure pump with a filter element (81) improved in its performance and service life are proposed.

Description

State of the art

High-pressure fuel pumps are in different designs, either as a radial piston pump or as In-line injection pump, successful on the market for many years.

With Increasing maximum injection pressures increase among others also the requirements for the separation of solid particles the fuel to damage at the high-pressure fuel pump or the downstream injectors to avoid.

There Most high-pressure fuel pumps currently on the market are throttled, is particularly in the low part load range of Internal combustion engine only a very small amount of fuel through the Suction valves of the high-pressure fuel pump in the delivery chamber or sucked their delivery rooms and there on the desired Injection pressure brought.

There the valve lifts the suction valve of the flow rate and the speed of the engine depend, are at low speeds and low load and the start of the engine, the strokes of the suction valve tiny.

Just if the valve lift of the suction valve is very small, can smallest particles that are in the sucked fuel, wed between valve seat and valve member of the suction valve. Consequently the suction valve will leak and the fuel pump may be required Delivery pressure not build more. Furthermore occurs at high speeds of the high-pressure fuel pump in the low pressure region of the fuel injection system pressure fluctuations that are caused by the high-pressure fuel pump. from that result unstable characteristics of the high-pressure fuel pump, what undesirable is.

Disclosure of the invention

Of the Invention is based on the object, a suction valve with filter element for one Provide high-pressure fuel pump, wherein the deposition rate of solid particles from the fuel before entering the Suction valve of the high-pressure fuel pump further improved and the Disadvantages of the known from the prior art solutions at least partially overcome become.

These Task is according to the invention in a Suction valve, especially for a high-pressure fuel pump or a suction-side regulated hydraulic pump, wherein the suction valve is a valve plate having an outer contour, preferably a prismatic or cylindrical outer contour, wherein the valve plate has a central bore, and wherein at least one the outer contour and the central bore connecting connecting hole provided is, with an extending in the axial direction and the Valve plate surrounding filter element, solved by that the active filter surface of the Filter element over the entire circumference of 360 ° of the Filter element extends.

Thereby Is it possible, the active filter area too maximize and thereby minimize the pressure loss on the filter element, the receptiveness of the filter element for To maximize contamination while maintaining maximum life the filter element and associated therewith also the high-pressure fuel pump to ensure.

A Particularly advantageous embodiment of the invention provides that the filter element is a perforated plate and / or a single-layer or multi-layered screen fabric includes, so that according to the requirements of the maximum Size of the shutdown Particles a suitable filter element can be used. perforated sheets have in addition to the very high precision, with those the holes can be made the advantage that they are mechanically very resilient and also at huge Do not avoid pressure differences on both sides of the perforated plate.

It has proven to be advantageous, the filter element cylindrical, single or double frusto-conical and / or toroidal form.

Which one these geometries in individual cases is given preference depends on the other part of how the filter element in the pump housing or on attached to the suction valve.

If the filter element on a cylindrical outer contour of the valve plate is fastened, it is usually advantageous to form the filter element cylindrical.

If However, the filter element between a paragraph of the housing in the Pump and a screw plug is clamped, it is advantageous if the filter element is single or double frusto-conical and / or torus, for example, with a c-shaped Profile in longitudinal section, is trained. Then that is can length tolerances through the elasticity of the filter element according to the invention be compensated in the axial direction readily. Also will a bypass flow of the fuel past the active filter surface thereby effectively prevented.

If necessary, it is possible at the axial En the filter element of a reinforcing ring, in particular made of plastic or metal, exhibit. If this reinforcing ring is made of plastic, the reinforcing ring can be sprayed onto the actual filter element. This plastic ring can also take over a sealing function in addition to the gain function. If the reinforcing ring is made of metal, it is often advisable to attach this reinforcing ring at the ends of the filter element by crimping.

Around to prevent the filter element from being relative to the plate valve twist or otherwise change its position, is about it provided, on a reinforcing ring one or more projections or form tabs, wherein the projections or lugs with the connecting holes the suction valve in the assembled state a positive connection produce.

alternative it is also possible that in the outer contour the valve plate is formed a recess and the filter element form-fitting is kept in the puncture.

A further, particularly advantageous embodiment of the invention sees before, between the outer contour the valve plate and the filter element to provide a toroidal intermediate piece, the intermediate piece anchored in the connecting holes of the valve plate and the Filter element at its ends form-fitting and / or cohesively with the intermediate piece connected is.

Thereby Is it possible, on the one hand, a secure positioning of the filter element relative to reach the valve plate. Furthermore, bypass currents are between the filter element and the suction valve effectively prevented and the intermediate piece can simultaneously serve to stabilize the filter element. Thereby, that the intermediate piece torus is, forms between the filter element and the intermediate piece an annular channel, so that independent of whether the filter element is locally added by impurities is the fuel almost unhindered in all connecting holes of the Pour in the valve plate can.

If the intermediate piece made of metal, preferably a thin-walled Sheet metal, it is possible, this intermediate piece as a closed torus on the valve plate postpone and in Provide area of the connection holes breakthroughs. If those breakthroughs positioned concentrically with the connection holes of the suction valve plate are formed in a further manufacturing step at the openings punctures, so that a positive Connection between adapter and the valve plate, in particular the connection holes, arises.

alternative it is also possible the intermediate piece to slit and the breakthroughs and the passages before assembling the intermediate piece to install on the suction valve. By widening the slotted spacer Is it possible, the passages into the connecting holes of the valve plate and insert thereby the desired positive Make connection. Subsequently, a closed annular Filter element, for example, by crimping on the intermediate piece sealing and positive fit attached. In this case, the slot in the intermediate piece is permanent locked.

alternative it is also possible the intermediate piece made of plastic, preferably a thermoplastic material to produce. In this case, it is recommended to spray the adapter on the valve plate, so that already by a positive and cohesive connection between intermediate piece and valve plate yields. Subsequently, the actual filter element at the intermediate piece, for example, by crimping or a forming process, such as welding or Beading with a heated tool, sealingly attached.

Depending on the requirements of the deposition rate of the filter element can this from a perforated plate, a single-layer or multi-layer filter fabric, especially Haver Porostar Hiflow, or a perforated plate become.

These multi-layer filter fabric can in particular with regard to mechanical strength, deposition rate and temperature resistance optimal for the operating conditions in a fuel injection system an internal combustion engine to be adjusted. They are also subject no aging and are not attacked by the fuel.

In addition, let These filter elements or filter fabric form well and at Need in the desired Form by sintering or other joining processes permanently in this form. Also a welding is quite possible. This may be required, for example, at the butt joint, if from a band-shaped Filter fabric an annular Filter element to be formed.

The aforementioned object is also achieved in a high-pressure fuel pump according to the independent claim 11, when the suction valve, which has a filter element according to one of the preceding claims, is used. It has surprisingly been found in the investigation of the suction valves and filter elements according to the invention that the filter elements according to the invention also effectively dampen the pressure fluctuations in the low pressure region of the fuel injection system. Consequently the characteristics of equipped with suction valves according to the invention high-pressure fuel pumps are much more stable, which is reflected in an improved quality of the pressure control on the delivery side of the high-pressure fuel pump and a reduced power requirement for the high-pressure fuel pump.

alternative it is possible to instead of firmly connecting the filter element to the suction valve, the Suction valve in a stepped extension of the element bore of the pump housing to arrange and the element bore through a screw plug to close. Then it is possible the filter element between the pump housing and the screw plug to tense. In particular, filter elements are particularly suitable for this purpose have a certain elasticity in the axial direction, such as frustoconical or toroidal Filter elements.

Further Advantages, features and details of the invention will become apparent the following description, with reference to the drawing several embodiments the invention are described in detail. The can in the claims and mentioned in the description Features individually for each itself or in any combination essential to the invention.

In the drawing shows: drawings

1 a section through an embodiment of a high-pressure fuel pump according to the invention;

2 a suction valve in longitudinal section;

3 a section along the line AA 2 and

4 to 11 Embodiments of inventive filter elements.

Embodiments of the invention

The 1 schematically shows a radial piston pump for high-pressure fuel supply in fuel injection systems, in particular common rail fuel injection systems, of internal combustion engines in section. In the 1 shown radial piston pump is equipped with an integrated demand quantity control. The flow rate control is low pressure side via a metering unit ZME, not shown.

In the 1 shown radial piston pump comprises one in a pump housing 1 mounted drive shaft 2 with two cams offset by 180 ° 36 , Against the cams 36 a piston is supported 8th from. However, the invention is not limited to high-pressure fuel pumps with a pump element, as will be apparent from the further description of the invention readily. The piston 8th is in an element hole 11 taken in the radial direction movable back and forth and limited at its the drive shaft 2 opposite end a delivery room 12 ,

At his to the drive shaft 2 directed towards the end of the piston 8th against a ground 20 a pestle 23 from. To the power transmission between pistons 8th and soil 20 of the plunger 23 to improve is on the piston 8th A plate 14 intended. This plate 14 can be either integral with the piston 8th or detachably attached thereto. Against the plate 14 is a spring 17 biased. The feather 17 pushes the piston 8th against the ground 20 , From the ground 20 of the plunger 23 extends a cylindrical guide body 26 in the direction of the delivery room 12 , The guide body 26 is part of the pestle 23 and prevent the tappets from tilting 23 in a guide hole 29 , The pestles 23 are in a cylinder head 1.2 displaceable.

In the ground 20 is a roller shoe 21 with a semicircular depression 27 provided for the storage of a roll 28 serves. The depression 27 and the role 28 Form a plain bearing while the roller 28 on the nock 36 the drive shaft 2 rolls. In the lateral direction becomes the role 28 in the guide body 26 fixed.

In the 1 shown radial piston pump serves to pressurize fuel that is supplied from a Vorförderpumpe from a tank with high pressure. In the delivery stroke, the pistons 8th due to the eccentric movement of the cams 36 the drive shaft 2 from the axis of rotation of the drive shaft camshaft 2 moved away. In the suction stroke, the pistons move 8th radially to the axis of the camshaft 2 to get fuel into the delivery room 12 to suck.

For this purpose, a suction valve is on the low pressure or suction side of the pumping chamber 51 in a filling hole 53 arranged and in a high-pressure line 55 a pressure-side check valve (not shown) is provided.

If now the plunger 23 from the cams 36 When the drive shaft is driven, it performs an oscillating motion on the piston 8th is transmitted.

As is clear from the 1 results, is the pump housing 1 constructed in several parts. It includes a crankcase 1.1 and a cylinder head 1.2 , In the cylinder head 1.2 are the element holes 11 , the funding room 12 as well as a suction valve 51 and a high pressure side check valve (not shown) arranged. In connection with the claimed invention, it is important that a filling bore 53 in one also in the cylinder head 1.2 trained annulus 59 empties. The annulus 59 is as a groove-shaped depression in a stepped bore in a stepped extension of the element bore 11 educated. At the top, this stepped hole is through a screw plug 61 which has a recess for the upper part of the suction valve 51 has, sealed sealing.

In all drawing figures are for same components used the same reference numerals and it applies to avoid repetition, what was said with respect to the other figures corresponding.

In 2 is the suction valve 51 shown greatly enlarged. The suction valve 51 includes a preferably circular valve plate 63 with a central hole 65 , At the in 2 lower end of the central bore 65 is a valve seat 67 educated. In the central hole 65 is a valve member comprising a valve stem 69 and a valve plate 71 slidably guided in the axial direction. The valve stem 69 the valve member protrudes on the valve seat 67 opposite side over the valve plate 63 out. At this end of the valve stem 69 is a valve spring 73 between the valve plate 63 and the valve stem clamped. For this purpose is a sleeve 75 with the shaft 69 pressed and / or welded. The valve spring 73 ensures that the valve plate 71 against the valve seat 67 is pressed and the suction valve 51 thus closed. Only if the pressure difference between the located above the valve disk part of the central bore 65 and below the valve disk 71 prevailing compressive forces the bias of the valve spring 73 overcome, then opens the valve member and the valve plate 71 lifts from the valve seat 67 from.

Between a generally cylindrical outer contour 77 the valve plate 63 and the central hole 65 are several connection holes 79 arranged.

The connection holes 79 Make a hydraulic connection between the annulus 59 (please refer 2 above) and above the valve disk 71 located part of the central hole 65 ago.

3 shows a section along the line AA 2 , From the 3 it becomes clear that the suction valve 51 from an annulus 59 surrounded by the filling hole 53 is supplied with fuel. This fuel is conveyed by a prefeed pump (not shown).

The valve plate 63 is in the illustrated embodiment with a cylindrical outer contour 77 provided and has four connection holes 79 which the outer contour 77 with the central hole 65 connect. In the center of the suction valve 51 is the valve stem 69 shown cut the valve member.

The 4 represents a section 1 is, in this enlarged view, a first embodiment of a filter element according to the invention 81 is drawn. This first embodiment of a filter element according to the invention 81 is designed as a frusto-conical perforated plate and / or filter mesh fabric. At a first axial end 83.1 it rests on the cylinder head 1.2 or a corresponding paragraph while it is at its other axial end 83.2 from the screw plug 61 depressed and against the cylinder head 1.2 is pressed. In this embodiment, the filter element 81 in the axial direction between the cylinder head 1.2 and the screw plug 61 clamped and sealed at the same time. This will also cause a bypass of fuel from the fueling hole 53 in the pump room 12 flows, on the active surface of the filter element 81 effectively prevented.

This filter element 81 can after inserting the suction valve in the cylinder head 1.2 be used and then with the tightening of the screw plug 61 in the cylinder head 1.2 fixed.

In 5 is that in 4 illustrated embodiment of a filter element 81 shown in a side view and partially cut. From the 5 can be the frusto-conical shape with the axial ends 83.1 and 83.2 recognize well. In the right part, where the filter element is partially cut free, the active filter surface can be opened 85 , which can be formed for example by a perforated plate or single or multi-ply filter fabric made of metal or plastic, recognize well.

In the 6 and 7 are other embodiments such between cylinder head 1.2 and screw plug 61 arranged filter elements 81 shown. In the embodiment according to 6 is the filter element 81 barrel-shaped or toroidal, so that an even greater elasticity and flexibility of the filter element 81 in the axial direction.

The third embodiment according to 7 has, as shown by the longitudinal section along the line AA (see 7c ) a "C" shaped longitudinal section. In this case, this embodiment of a filter element according to the invention 81 like the other embodiments also, from a Sheet metal ring or a short pipe section are made by forming. The active filter area 85 is in the cylindrical part of the filter element 81 arranged and can be worked out, for example, by punching or laser or erosion from the blank of the filter element.

Also in this embodiment, the required elasticity is given in the axial direction, so that the compensation of length tolerances is readily possible. The filter element is so to speak resilient and sealing between screw plug 61 and the cylinder head 1.2 clamped.

In 8th is shown greatly enlarged the construction of a multi-layer filter fabric. It is clear that the multi-layer filter fabric consists of different layers of wire mesh, with wire diameter and the mesh size of the individual layers differ from each other. This makes it possible to optimize the desired stability, the desired filter rate and the desired particle deposition rate. For example, large particles can enter the filter fabric from the relatively large meshes of the first layer 87.1 or the second layer 87.2 be filtered out. The final Feinstfilterung is from a third location 87.3 made, in which only smaller particles naturally arrive, so that this third layer 87.3 only very slowly added.

In 9 is another embodiment of a filter element according to the invention 81 shown. This filter element 81 is an annular connection spacer, which has a "C" -shaped profile in longitudinal section. This annular spacer 91 has roughly the cross section of a "drop-center rim". At the axial ends 83.1 and 83.2 is a ring-shaped filter fabric crimped. In the "Tiefbett" of the intermediate piece 91 are breakthroughs 93 with molded passages 95 educated. Number, arrangement and dimensions of the apertures 93 and the passages 95 correspond to those of the connection holes 79 in the valve plate 63 (see for example 3 and 10 ).

With the help of the passages 95 is it possible (see 10 ), a positive and simultaneously sealing connection between the filter element 81 and the valve plate 63 or the connection holes 69 manufacture.

To the filter element 81 according to the 9 and 10 or with the valve plate 63 of the suction valve 51 There are two ways to connect. In the first alternative, the intermediate piece 91 a slot on, leaving the breakthroughs 93 and the passages 95 outside the suction valve 51 can be completed and then this slotted spacer 91 is bent up until the breakthroughs 95 in the connection holes 79 the valve plate 63 engage. Subsequently, the filter fabric 87 by crimping with the spacer 91 connected.

Alternatively, it is also possible, the intermediate piece 91 form as a closed ring and initially only the breakthroughs 93 manufacture. In this state, formed as a closed ring spacer 91 on the valve plate 63 deferred and the breakthroughs 93 concentric with the connection bores 69 arranged. In this position are now the passages 95 produced by forming. This creates a positive connection between the valve plate 63 and intermediate piece 91 , Subsequently, the filter fabric 87 by crimping on the intermediate piece 91 attached.

This embodiment is characterized by a very small space requirement. In addition, the active filter area can be further increased since it is possible to increase the axial length of the filter fabric 87 to increase significantly and in particular in the field of screw plug 61 in, when in the screw plug 61 a corresponding recess (not shown) is formed on the front side. Furthermore, the connector serves 91 for stabilizing the filter fabric 87 so that this can be optimized only with regard to the filter properties.

The intermediate piece 91 can also be made of plastic. In this case, it is recommended that the intermediate piece 91 by injection molding on the valve plate. This means that the valve plate is inserted in this injection mold and then the intermediate piece 91 is injected. Subsequently, in a further operation, the filter fabric 87 at the intermediate piece, for example by crimping with a hot tool, which the intermediate piece 91 in the area of the axial ends 83 brought into a plastic state, be attached.

Another embodiment of a filter element according to the invention 81 is in 11 shown. In this embodiment, at the axial ends 83 of filter fabric 87 one circumferential plastic ring each 97 educated. On each of these plastic rings is a detent 99 formed, which is a positive connection of the plastic rings 97 with the connection holes 79 accomplished. Again, it is possible the connection between the filter element 81 , but especially the plastic rings 97 and the valve plate 63 by overmolding the valve plate 63 manufacture. Subsequently, in another Ar The cylindrical filter fabric is made by ultrasonic welding or another cohesive joining process with the plastic rings 97 get connected.

Claims (13)

Suction valve, in particular for a high-pressure fuel pump or a hydraulic pump, wherein the suction valve ( 51 ) a valve plate ( 63 ) with an outer contour ( 77 ), preferably a prismatic or cylindrical outer contour, and a central bore ( 65 ), with at least one of the outer contour ( 77 ) and the central bore ( 65 ) connecting bore ( 79 ), and with an axially extending and the valve plate ( 63 ) surrounding filter element, characterized in that an active filter surface ( 85 ) of the filter element ( 81 ) the valve plate ( 63 ) completely encloses. Suction valve according to claim 1, characterized in that the filter element ( 81 ) is formed from a perforated plate and / or single-layer or multi-layered screen fabric. Suction valve according to one of the preceding claims, characterized in that the filter element ( 81 ) is cylindrical, single or double frusto-conical and / or toroidal. Suction valve according to one of the preceding claims, characterized in that the filter element ( 81 ) at its ends ( 83 ) a reinforcing ring ( 97 ), in particular of plastic or metal. Suction valve according to claim 4, characterized in that at least one reinforcing ring ( 97 ), one or more projections ( 95 ) or noses ( 99 ) are formed, and that the projections ( 95 ) or noses ( 99 ) with the connecting bores ( 79 ) establish a positive connection. Suction valve according to one of the preceding claims, characterized in that in the outer contour ( 77 ) of the valve plate ( 63 ) is formed a recess, and that the filter element ( 81 ) is held positively in the groove. Suction valve according to one of the preceding claims, characterized in that between the outer contour ( 77 ) of the valve plate ( 63 ) and the filter element ( 81 ) a preferably torusfömiges intermediate piece ( 91 ) is provided that the intermediate piece ( 91 ) in the connection bores ( 79 ) and that the filter element ( 81 ) at its ends ( 83 ) positively and / or cohesively with the intermediate piece ( 91 ) connected is. Suction valve according to one of the preceding claims, characterized in that the intermediate piece ( 91 ) made of metal, preferably a thin-walled sheet. Suction valve according to claim 7, characterized in that the intermediate piece ( 91 ) made of plastic, preferably a thermoplastic material. Suction valve according to one of the preceding claims, characterized in that between the filter element ( 81 ) is cylindrical, torusfömig, in particular with a curved torus, or frusto-conical. Filter element according to one of the preceding claims, characterized in that the filter element ( 81 ) consists of a single-layer or a multi-layer filter fabric, preferably Haver Porostar Hiflow, and / or a perforated plate. High-pressure fuel pump for the fuel injection system of an internal combustion engine, in particular in a common rail injection system, with one in a pump housing ( 1 ) mounted drive shaft ( 2 ), with at least one with respect to the drive shaft radially in each case an element bore ( 11 ) arranged piston ( 8th ), wherein the at least one piston ( 8th ) by turning the drive shaft ( 2 ) in the element bore ( 11 ) is movable in the radial direction to and fro, wherein the piston ( 8th ) a delivery room ( 12 ) and with one into an annulus ( 59 ) of the pump housing ( 1.2 ) used suction valve ( 51 ), characterized in that the suction valve ( 51 ) is designed according to one of the preceding claims. Suction valve according to one of the preceding claims, characterized in that the suction valve ( 51 ) in a stepped extension of the element bore ( 11 ) is arranged, that the element bore ( 11 ) by a screw plug ( 61 ) is closed, and that the filter element ( 81 ) between the pump housing ( 1.2 ) and the screw plug ( 61 ) is braced.