WO2010102850A1

WO2010102850A1 - Suction valve for a high pressure fuel pump

Info

Publication number: WO2010102850A1
Application number: PCT/EP2010/050565
Authority: WO
Inventors: Josef Guentert; Volkhard Ammon; Jochen Aleker
Original assignee: Robert Bosch Gmbh
Priority date: 2009-03-10
Filing date: 2010-01-19
Publication date: 2010-09-16
Also published as: EP2406488A1; DE102009001433A1

Abstract

The invention relates to a suction valve (51) having a filter element (81) and to a high pressure pump having a filter element (81) that is improved with regard to capacity and service life.

Description

description

title

Mouth valve for a high-pressure fuel pump

State of the art

High-pressure fuel pumps in various designs, whether as a radial piston pump or as a series injection pump, have been successful on the market for many years.

As the maximum injection pressures increase, among other things, the requirements for the separation of solid particles from the fuel increase in order to avoid damage to the high-pressure fuel pump or the downstream injectors.

Since most of the high-pressure fuel pumps currently on the market are intake throttle-controlled, only a very small amount of fuel is sucked through the suction valves of the high-pressure fuel pump into the pumping chamber or their pumping chambers, and brought there to the desired injection pressure, especially in the low part load range of the internal combustion engine.

Since the valve strokes of the suction valve depend on the flow rate and the speed of the internal combustion engine, the strokes of the suction valve are very small at low speeds and low load and when starting the engine.

Especially when the valve lift of the suction valve is very small, smallest particles that are in the sucked fuel, between the valve seat and Wedge valve member of the suction valve. As a result, the suction valve is leaking and the fuel pump can not build up the required delivery pressure. Furthermore occurs at high speeds of the high-pressure fuel pump in the low pressure region of the fuel injection system pressure fluctuations, which are caused by the high-pressure fuel pump. This results in unstable characteristics of the high-pressure fuel pump, which is undesirable.

Disclosure of the invention

The invention has for its object to provide a suction valve with a filter element for a 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 overcome the disadvantages of the known from the prior art solutions at least partially become.

This object is achieved with a suction valve, in particular for a Kraftstoffh och d jerk pump or a suction side controlled 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 outer contour and the central bore connecting connecting bore is provided with a extending in the axial direction and surrounding the valve plate filter element, achieved in that the active filter surface of the filter element extends over the entire circumference of 360 ° of the filter element.

This makes it possible to maximize the active filter area and thereby minimize the pressure loss on the filter element, to maximize the capacity of the filter element for contamination while ensuring maximum service life of the filter element and, associated therewith, the high pressure fuel pump.

A particularly advantageous embodiment of the invention provides that the filter element comprises a perforated plate and / or a single-layer or multi-layer screen fabric, so that a suitable filter element can be used in accordance with the requirements of the maximum size of particles to be shut off. Perforated sheets, in addition to the very high precision with which the holes are can be made, the advantage that they are mechanically very resilient and even with large pressure differences on both sides of the perforated plate do not dodge.

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

Which of these geometries is given preference in the individual case depends inter alia on how the filter element is fastened in the pump housing or on the suction valve.

When the filter element is attached to a cylindrical outer contour of the valve plate, it is usually advantageous to form the filter element cylindrical.

However, when the filter element is clamped between a shoulder of the housing in the pump and a screw plug, it is advantageous if the filter element is a simple or double frusto-conical and / or toroidal, for example, with a c-shaped profile in longitudinal section formed. Then namely length tolerances can be compensated by the elasticity of the filter element according to the invention in the axial direction readily. Also, a bypass flow of the fuel past the active filter surface is thereby effectively prevented.

If necessary, it is possible to have at the axial ends of the filter element a reinforcing ring, in particular made of plastic or metal. 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.

In order to prevent the filter element from twisting or otherwise changing its position relative to the plate valve, provision is also made to form one or more projections or lugs on a reinforcing ring, the projections or lugs being connected to the connecting bores of the suction valve Condition establish a positive connection. Alternatively, it is also possible that in the outer contour of the valve plate, a puncture is formed and the filter element is positively held in the groove.

A further, particularly advantageous embodiment of the invention provides to provide a toroidal intermediate piece between the outer contour of the valve plate and the filter element, wherein the intermediate piece is anchored in the connecting holes of the valve plate and the filter element is positively connected at its ends and / or materially connected to the intermediate piece ,

This makes it possible, on the one hand to achieve a secure positioning of the filter element relative to the valve plate. Furthermore, bypass flows between the filter element and the suction valve are effectively prevented and the intermediate piece can simultaneously serve to stabilize the filter element. Characterized in that the intermediate piece is torus-shaped, an annular channel is formed between the filter element and the intermediate piece, so that regardless of whether the filter element is locally added by impurities, the fuel can flow almost unhindered in all connecting holes of the valve plate.

If the intermediate piece consists of metal, preferably a thin-walled metal sheet, it is possible to push this intermediate piece onto the valve plate as a closed torus and to provide openings in the area of the connecting bores. If these openings are positioned concentrically to the connecting holes of the suction valve plate, passages are formed in a further production step at the openings, so that a positive connection between the intermediate piece and the valve plate, in particular the connecting holes, is formed.

Alternatively, it is also possible to slit the intermediate piece and to install the apertures and the passages before mounting the intermediate piece on the suction valve. By widening the slotted intermediate piece, it is possible to introduce the passages into the connecting bores of the valve plate and thereby produce the desired positive connection. Subsequently, a closed annular filter element, for example, by crimping on the intermediate piece sealingly and positively secured. In this case, the slot in the spacer is permanently closed. Alternatively, it is also possible to produce the intermediate piece from plastic, preferably a thermoplastic. In this case, it is advisable to spray the intermediate piece on the valve plate, so that even this results in a positive and cohesive connection between the intermediate piece and the valve plate. Subsequently, the actual filter element is attached to the intermediate piece, for example by crimping or a forming process, such as welding or crimping with a heated tool, sealing.

Depending on the requirements of the deposition rate of the filter element this can be made of a perforated plate, a single-layer or multi-layer filter fabric, in particular Haver Porostar Hiflow, or a perforated plate.

With regard to mechanical strength, deposition rate and temperature resistance, these multilayer filter fabrics can be optimally adapted to the operating conditions in a fuel injection system of an internal combustion engine. They are also not subject to aging and are not attacked by the fuel.

In addition, these filter elements or filter fabric can be well formed and, if necessary in the desired shape by sintering or other joining processes permanently in this form. Welding is also possible. This may be required, for example, at the butt joint if an annular filter element is to be formed from a band-shaped filter fabric.

The aforementioned object is also achieved in a high-pressure fuel pump according to the independent claim 1 1, 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. As a result, 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. Alternatively, it is possible, instead of firmly connecting the filter element with the suction valve to arrange the suction valve in a stepped extension of the element bore of the pump housing and to close the element bore by a screw plug. Then it is possible to clamp the filter element between the pump housing and the screw plug. In particular, filter elements which have a certain elasticity in the axial direction, such as, for example, frusto-conical or tubular filter elements, are particularly suitable for this purpose.

Further advantages, features and details of the invention will become apparent from the following description in which several embodiments of the invention are described in detail with reference to the drawing. The features mentioned in the claims and in the description may each be essential to the invention individually or in any desired combination.

In the drawing shows:

drawings

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

Figure 2 is a suction valve in longitudinal section;

Figure 3 is a section along the line A-A of Figure 2 and

Figures 4 to 1 1 embodiments of inventive filter elements.

Embodiments of the invention

1 shows schematically 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. The radial piston pump shown in Figure 1 is equipped with an integrated demand quantity control. The flow rate control is low pressure side via a metering unit ZME, not shown. The radial piston pump shown in Figure 1 comprises a mounted in a pump housing 1 drive shaft 2 with two offset by 180 ° seconded cam 36. Against the cam 36, a piston 8 is supported. 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 8 is received in an element bore 1 1 in the radial direction movable back and forth and limited at its end remote from the drive shaft 2 a delivery chamber 12th

At its end directed towards the drive shaft 2, the piston 8 is supported against a bottom 20 of a plunger 23. In order to improve the power transmission between the piston 8 and the bottom 20 of the plunger 23, a plate 14 is provided on the piston 8. This plate 14 may either be integral with the piston 8 or detachably secured thereto. Against the plate 14, a spring 17 is biased. The spring 17 presses the piston 8 against the bottom 20. From the bottom 20 of the plunger 23 extends a cylindrical guide body 26 in the direction of the delivery chamber 12. The guide body 26 is part of the plunger 23 and prevent tilting of the plunger 23 in a guide bore 29th The plungers 23 are displaceable in a cylinder head 1.2.

In the bottom 20, a roller shoe 21 is provided with a half-round recess 27 which serves to support a roller 28. The recess 27 and the roller 28 form a sliding bearing, while the roller 28 rolls on the cam 36 of the drive shaft 2. In the lateral direction, the roller 28 is fixed in the guide body 26.

The illustrated in Fig. 1 radial piston pump serves to pressurize fuel, which is supplied from a Vorförderpumpe from a tank with high pressure. In the delivery stroke, the pistons 8 are moved away from the axis of rotation of the drive shaft camshaft 2 as a result of the eccentric movement of the cams 36 of the drive shaft 2. In the suction stroke, the pistons 8 move radially toward the axis of the camshaft 2 in order to suck fuel into the delivery chamber 12.

For this purpose, a suction valve 51 is arranged in a filling bore 53 on the low pressure or suction side of the delivery chamber and in a high pressure line 55, a pressure-side check valve (not shown) is provided. Now, when the plunger 23 is driven by the cam 36 of the drive shaft, it performs an oscillating movement, which is transmitted to the piston 8.

As is apparent from the figure 1, the pump housing 1 is constructed in several parts. It comprises a crankcase 1.1 and a cylinder head 1.2. In the cylinder head 1.2, the element bores 11, the delivery chamber 12 and a suction valve 51 and a high-pressure side check valve (not shown) are arranged. In connection with the claimed invention, it is of importance that a filling bore 53 opens into a likewise formed in the cylinder head 1.2 annular space 59. The annular space 59 is formed as a groove-shaped depression in a stepped bore in a stepped extension of the element bore 11. At the top, this stepped bore is sealed by a closure screw 61, which has a recess for the upper part of the suction valve 51.

In all drawing figures, the same reference numerals are used for the same components and it is, in order to avoid repetition, with respect to the other figures said accordingly.

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

Between a generally cylindrical outer contour 77 of the valve plate 63 and the central bore 65 a plurality of connecting holes 79 are arranged. The connecting bores 79 establish a hydraulic connection between the annular space 59 (see FIG. 2, top) and the part of the central bore 65 located above the valve disk 71.

FIG. 3 shows a section along the line A-A from FIG. 2. It becomes clear from FIG. 3 that the suction valve 51 is surrounded by an annular space 59, which is supplied with fuel via the filling bore 53. This fuel is conveyed by a prefeed pump (not shown).

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

FIG. 4 shows a section from FIG. 1, with a first exemplary embodiment of a filter element 81 according to the invention being shown in this enlarged illustration. This first embodiment of a filter element 81 according to the invention is designed as a frusto-conical perforated plate and / or filter mesh fabric. At a first axial end 83.1 it is supported on the cylinder head 1.2 or a corresponding shoulder, while it is pressed down at its other axial end 83.2 by the locking screw 61 and pressed against the cylinder head 1.2. In this embodiment, the filter element 81 is clamped in the axial direction between the cylinder head 1.2 and the locking screw 61 and sealed at the same time. As a result, a bypass of the fuel flowing from the filling bore 53 into the delivery chamber 12 is also effectively prevented from passing past the active surface of the filter element 81.

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

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

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

The third embodiment according to FIG. 7 has, as shown by the longitudinal section along the line A-A (see FIG. 7c), a "C" shaped longitudinal section. In this case, this embodiment of a filter element 81 according to the invention, as the other embodiments also, are made from a sheet metal ring or a short pipe section by forming. The active filter surface 85 is disposed in the cylindrical portion of the filter element 81 and may be machined out of the blank of the filter element by, for example, punching or lasering or eroding.

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 clamped so to speak resiliently and sealingly between the plug 61 and the cylinder head 1.2.

In Figure 8 is greatly enlarged the structure of a multi-layer filter fabric shown. 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, when entering the filter fabric, large particles can be filtered out of the relatively large meshes of the first layer 87.1 and the second layer 87.2. The final Feinstfilterung is made by a third layer 87.3, arriving naturally only smaller particles, so that this third layer 87.3 added only very slowly.

FIG. 9 shows a further exemplary embodiment of a filter element 81 according to the invention. This filter element 81 is an annular connecting spacer, which has a "C" -shaped profile in longitudinal section. This annular spacer 91 has approximately the cross section of a "Tiefbettfelge". At the axial ends 83.1 and 83.2 an annular filter fabric is crimped. In the "deep bed" of the intermediate piece 91 openings 93 are formed with molded passages 95. Number, arrangement and dimensions of the apertures 93 and the passages 95 correspond to those of the communication holes 79 in the valve plate 63 (see, for example, Figure 3 and Figure 10).

With the aid of the passages 95, it is possible (see FIG. 10) to produce a positive and simultaneously sealing connection between the filter element 81 and the valve plate 63 or the connecting bores 69.

In order to produce the filter element 81 according to FIGS. 9 and 10 or to connect it to the valve plate 63 of the suction valve 51, there are two possibilities. In the first alternative, the intermediate piece 91 has a slot, so that the openings 93 and the passages 95 can be completed outside the suction valve 51 and then this slotted intermediate piece 91 is bent so far until the openings 95 in the connecting holes 79 of the valve plate 63rd engage. Subsequently, the filter cloth 87 is connected by crimping with the intermediate piece 91.

Alternatively, it is also possible to form the intermediate piece 91 as a closed ring and initially to produce only the openings 93. In this state, formed as a closed ring spacer 91 can be pushed onto the valve plate 63 and the openings 93 arranged concentrically to the connecting holes 69. In this position, the passages 95 are now produced by forming. This results in a positive connection between the valve plate 63 and spacer 91. Subsequently, the filter fabric 87 is fixed by crimping on the intermediate piece 91.

This embodiment is characterized by a very small space requirement. In addition, the active filter surface can be increased again, since it is possible to increase the axial length of the filter cloth 87 significantly, and in particular in the region of the screw plug 61, if in the locking screw 61 has a corresponding recess (not shown) on the front side is trained. Furthermore, the connector 91 serves to stabilize the filter fabric 87, so that it 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 to produce the intermediate piece 91 by injection molding on the valve plate. This means that the valve plate is inserted into this injection mold and then the intermediate piece 91 is molded. Subsequently, in a further operation, the filter fabric 87 on the intermediate piece, for example by crimping with a hot tool, which brings the intermediate piece 91 in the region of the axial ends 83 in a plastic state, are attached.

A further exemplary embodiment of a filter element 81 according to the invention is shown in FIG. 11. In this embodiment, a circumferential plastic ring 97 is formed at the axial ends 83 of the filter fabric 87 each. At these plastic rings each have a detent 99 is formed, the rings a positive connection of the plastic 97 accomplished with the connecting holes 79. Again, it is possible to make the connection between the filter element 81, but in particular the plastic rings 97 and the valve plate 63 by molding the valve plate 63. Subsequently, in a further operation, the cylindrical filter fabric by ultrasonic welding or another cohesive joining method with the plastic rings 97 are connected.

Claims

claims

A suction valve, in particular for a fuel-fired pump or a hydraulic pump, wherein the suction valve (51) has a valve plate (63) with an outer contour (77), preferably a prismatic or cylindrical outer contour, and a central bore (65) with at least a connecting bore (79) connecting the outer contour (77) and the central bore (65), and having a filter element extending in the axial direction and surrounding the valve plate (63), characterized in that an active filter surface (85) of the filter element (81 ) completely encloses the valve plate (63).

2. 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.

3. Suction valve according to one of the preceding claims, characterized in that the filter element (81) is cylindrical, single or double ke- gelstumpfförmig and / or torus-shaped.

4. Suction valve according to one of the preceding claims, characterized in that the filter element (81) at its ends (83) has a reinforcing ring (97), in particular made of plastic or metal.

5. Suction valve according to claim 4, characterized in that at least one reinforcing ring (97), one or more projections (95) or lugs (99) are formed, and that the projections (95) or lugs (99) with the connecting holes ( 79) produce a positive connection.

6. Suction valve according to one of the preceding claims, characterized in that in the outer contour (77) of the valve plate (63) has a recess is formed, and that the filter element (81) is held positively in the groove.

7. 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 connecting holes ( 79) is anchored, and that the filter element (81) at its ends (83) is positively and / or materially connected to the intermediate piece (91).

8. Suction valve according to one of the preceding claims, characterized in that the intermediate piece (91) consists of metal, preferably a thin-walled sheet.

9. suction valve according to claim 7, characterized in that the intermediate piece (91) made of plastic, preferably a thermoplastic material.

10. 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.

1 1. 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.

12. 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 (1 1) arranged piston ( 8), wherein the at least one piston (8) by rotation of the drive shaft (2) in the element bore (1 1) in the radial direction is movable back and forth, the piston (8) defining a delivery chamber (12), and with a in a ring space (59) of the pump housing (1.2) inserted suction valve (51), characterized in that the suction valve (51) is designed according to one of the preceding claims.

13. Suction valve according to one of the preceding claims, characterized in that the suction valve (51) in a stepped extension of the element bore (1 1) is arranged, that the element bore (1 1) by a locking screw (61) is closed, and that Filter element (81) between the pump housing (1.2) and the Verschlusschraube (61) is braced.