EP1411236A2 - Device for damping of pressure pulsations in a fluid system, especially in a fuel system of an internal combustion engine - Google Patents

Abstract

The pressure pulsation damping device has a housing (38,40) having at least one working space (66) communicating with the fuel system, in which a gas volume (58) sealed by a metal membrane (54a,54b) is provided. The membrane can be provided by a thin-walled metal pipe which is sealed at its ends, the gas volume exhibiting an overpressure at a normal atmospheric pressure.

Description

State of the art

The invention relates to a device for damping of Pressure pulsations in a fluid system, in particular in a fuel system of an internal combustion engine, with a Housing and with at least one working space, which at least partially communicates with the fluid system.

Such a device is known from DE 195 39 885 A1 known. There is a fuel system one Internal combustion engine with direct fuel injection shown. From a prefeed pump, the fuel is too promoted a high-pressure piston pump, which the Fuel is compressed to a very high pressure. Of the High-pressure piston pump, the fuel enters a Fuel rail ("Rail"). The high pressure piston pump is from a camshaft of Internal combustion engine driven. To the flow rate of the High-pressure piston pump regardless of the speed of the To be able to adjust the camshaft is on Quantity control valve provided. Through this, the Delivery chamber of the high-pressure piston pump during a Delivery hubs briefly with the between the electrical Pre-feed pump and the high-pressure fuel pump located Be connected area of the fuel system.

As a result, however, significant pressure pulsations in initiated this area of the fuel system. Around to dampen, there is provided a pressure damper. This consists of a housing and a piston, which of a spring is biased.

Also known from the market is a pressure damper, which with a spring-biased rubber membrane is working. So with pressure-free systems (thus eg with switched off internal combustion engine) the rubber membrane is not is unduly stretched over time is a stop present, at which the membrane at low pressure supported.

In the fuel system known from DE 195 39 885 A1 is the pressure between the priming pump and the High pressure piston pump approximately constant. In modern However, this pressure can be variable for fuel systems. Typically, it is between 0.5 and 8 bar, wherein an overload safety up to about 10 to 12 bar must be present. Will the known pressure damper, which has a rubber membrane, in such Fuel system used, there is a risk that at a low system pressure, for example. Of 0.5 bar and the superimposed pressure pulsations the rubber membrane on the Stop strikes. As a result, the damping effect of Weakened damper and it may damage the rubber membrane occur. From DE 195 39 885 A1 known pressure damper with a piston and a spring In turn, if used in such a way would have Very large fuel system with variable admission pressure.

The present invention therefore has the object, a Device of the type mentioned in the above way, that they are in a variable-pressure fuel system can be used, but it builds small and a has a long service life.

This object is achieved in a device of the initially mentioned type solved in that within the Workspace at least one dense by a membrane completed gas volume is present.

Advantages of the invention

By using a sealed gas volume can the compressibility of gases to be exploited, the required for the damping of pressure pulsations ensure elastic movement of the membrane. It will the membrane by no mechanical elements which significantly increases their lifespan and that Risk of damage reduced. In addition, can Such a gas volume in almost any geometric shape can be realized. So it can be very to save space in the fluid system. One further advantage of the device according to the invention exists in that a leakage line can be dispensed with, which further simplifies the construction of the fuel system.

Advantageous developments of the invention are in Subclaims specified.

In a first development it is proposed that the Membrane is made of metal. Such a membrane has various advantages: First, such a membrane compared to conventional gases and also to fluids very tight. Here plays in particular the high tightness of Metal membranes a positive over HC emissions Role. On the other hand occurs in a metal diaphragm also low pressures, for example, when switched off Internal combustion engine, over time no overstretching, so that a damper device with a metal diaphragm in a fluid system can be used, which has a in having a wide range of variable fluid pressure.

It is also advantageous if the gas volume through a thin-walled and gas-tight at its ends Metal tube is formed. This is very easy and inexpensive to realize.

If at least one outer wall of the work space also is designed as a membrane, you get on a minimum Space an additional hydraulically effective area. The Effectiveness of the device according to the invention is This again significantly increased, at the same time small footprint.

It is particularly advantageous if the enclosed Gas volume at a standard external pressure (for example, 1013 hPa) has a defined pressure, preferably one Overpressure. With such a defined pressure, the "Spring stiffness" can be adjusted. Usually will an overpressure in the trapped gas volume in the Comparison to the external pressure are chosen, because thereby can the whole possible voltage range (train and pressure) be exploited of the membrane material.

It is also conceivable, however, a negative pressure or standard pressure. Preferably, such an internal overpressure is selected, which is about half of the maximum Operating pressure, minus the pressure increase caused by the compression of the component arises, corresponds.

It can also by minimizing the trapped Gas volume optimized the effectiveness of the gas volume become. By such a minimization is namely a realized higher spring stiffness. This allows the Diaphragm thinner and tensions in the Membrane material can be minimized. In addition, in the entire work area a non-stop working of the Device allows. Furthermore, the burden on the entire operating range reduced because of the enclosed internal pressure the pressure difference over the Membrane wall is reduced. This allows the membrane geometry to higher strokes and lower pressure load or small installation volume can be designed.

The gas volume can be a closable opening have, over which the pressure can be adjusted. This facilitates the production of gas volume. Otherwise would have to manufacture itself at a certain pressure respectively.

Particularly advantageous is that embodiment of the Device according to the invention, in which the membrane has at least one bead. By such a bead can the spring properties of the membrane itself and also their strength properties significantly influenced become. With a bead, the membrane can thus optimally adapted to the individual requirements of the fluid system become. Above all, the damper with comparable Construction volume have even more damping volume, or alternatively be built smaller. The beads can different height and / or a different one Course and / or have a different cross-section.

This way you can get an unbalanced one Spring stiffness of the membrane depending on the load direction achieve.

As a result, in the main field of work, for example Druckdämpfervorrichtung a targeted, eg. A largely constant and rather soft spring constant of Membrane can be achieved. In rarely used Operating areas, on the other hand, can have a higher rigidity will be realized. That way you can not do one linear or only piecewise linear spring characteristic to reach. Ultimately, this is an optimal Damping effect in the entire operating range of the Fluid system achieved at the same time low space.

The beads can also be shaped so that the maximum stress does not occur at the edge of the membrane, and the mechanical stresses over the surface of the membrane distributed as evenly as possible. Furthermore, can by a corresponding membrane design the entire Material bandwidth in the tensile and compressive stress range be used.

It can also be provided that the membrane at least has a stop area, which at a maximum Deflection of the membrane with a counter surface in plant comes. The maximum deflection is chosen so that Damage to the membrane, such as a plastic deformation, just barely avoided. These Device is therefore at least in a certain range "overload-proof", that is, it still shows overloading a damping function without being damaged.

In this regard, it is proposed that the Counter surface on the housing, on a separate Stop member, and / or on another membrane is trained. The overload protection can so on realized various very simple and inexpensive types become. The stop surface on the housing, for example be made by deep drawing, which is very simple and is inexpensive. Also, a separate stop part is inexpensive, taking for a same damper different stop parts can be provided so that the same device easily adapted to different Operating conditions can be adjusted. The Stop surface on another membrane again saves Space.

In a further development is also proposed that the trapped gas volume through a filling area is reduced. This filling area can also by the stopper (this then acts as a "filler") or a housing portion are formed. As already above may be mentioned by reducing the volume of gas the spring stiffness of the device can be increased. In the As a result, the membrane can be thinner, giving good dynamics and a small size results.

An advantageous embodiment of the invention Device is that the gas volume through At least two membranes are limited in the area their edges are clamped. Such a pressure damper builds comparatively flat. All the more so if the Membranes are substantially parallel. It is Basically, of course, conceivable that the gas volume in the between the two membranes lying space at their Merging is introduced so that on one Befüllöffnung can be dispensed with.

Also proposed is such a device, in which formed the gas volume between the two membranes is and the two membranes each at least one Have stop surface or a mating surface, which is at a maximum deflection of the two membrane touch. This exploits that in the case of a high Pressure to move the two membrane surfaces to each other. When they get in touch with each other, they rely on each other with the stop surfaces from each other. These Stop surfaces can be designed plan to a to get clean contact of the membranes to each other. A Overload of the membranes at too high pressure is thereby reliably excluded, without a separate Stop is required.

It is also possible that the edges of the two membrane tightly interconnected and radially inward of the Sealing line are clamped. Especially if the Connection through a weld is done by this Design of the device according to the invention prevents that the welds provide additional mechanical forces have to endure. The sealing connection thus serves only for Sealing and does not have to take on other tasks and can thus ensure especially high tightness requirements fulfill. For the evaluation of the durability of the Pressure damper according to the invention must therefore only the Membranes themselves are considered.

It is particularly advantageous if the clamping has a constructive elasticity. Below this is understood such elasticity, the "constructive For example, a retaining ring made of a rubber elastic material can be used or it can a metal bracket can be used which has a Has spring section. This is on the one hand a safe Fixation of the membranes achieved, and on the other hand can Manufacturing tolerances are compensated. in principle can attack the restraint at any point on the membrane, However, an approach in the area of a particularly favorable Center plane of the two membranes.

The cost of the device according to the invention will be reduced if the two membranes are identical.

The space of the device according to the invention is particularly small if the working space of the two membranes in two Fluid areas is divided, which by a Communicate fluid communication with each other.

An annular spacer between the two Membranes defined or increased in a simple manner the enclosed gas volume. In this case it is inexpensive possible, the fluid connection, which is the two Fluid areas of the working space connects, in form the spacer.

It is particularly advantageous if the device in a Housing a fuel pump is integrated. Do there the benefits of the invention particularly strong noticeable, since such a fuel pump usually should build very small.

In fuel pumps are often rotating areas present in which shafts or pistons are arranged. In In these cases, the inventive Damping device accommodated particularly space-saving be when the workspace includes an annulus and the Gas volume is also annular. Especially advantageous It is when the work space and the gas volume a cylinder of a fuel pump at least approximately are arranged coaxially with the cylinder axis. The pressure damper surrounds so to speak the cylinder and in this existing piston, which additionally one more Noise damping causes.

It is also proposed that the gas volume in the Art a spiral is disposed in the annulus, wherein the Spiral and the annulus are at least approximately coaxial. By such a spiral results in a large Deformation surface, which is a particularly effective Pulsation damping contributes.

When the spiral gas volume against the outer wall of Workspace is biased, results without additional Parts a fixation of the gas volume in the working space.

The effective area of the gas volume can be increased again when the spiral gas volume is helical extends in the axial direction of the working space.

Again, the fixation of the gas volume without allows additional parts when the spiral and helical gas volume in the axial direction against the Front ends of the working space is biased.

Another preferred embodiment of the invention Device is characterized in that the gas volume filled with helium. This facilitates the detection a leak.

In addition, the membrane and / or the housing may be magnetic be. By appropriate manufacturing process (For example, mechanical rolling and embossing) arises in Material martensitic structure ("forming martensite"), which has magnetic properties. If those magnetic property targeted in the corresponding Component is left, the device in the fluid capture existing magnetic dirt particles and their prevent further distribution. This increases the Reliability of the components present in the fluid system, for example, a pump. In addition, costs are saved, because the time-consuming demagnetization of the component is eliminated. As in the device no directly adjacent and relatively movable parts are present, cause the trapped dirt particles no Functional damage to the device.

Furthermore, it is possible that the membrane of a Band material is produced, which residual stresses having. Such residual stresses lead during the Forming process to a flat distortion, so that the Material in the deformed state is discarded. This one can now targeted for the simplification of the production of Membrane can be used, especially if this Having at least one Faltenbalgabschnitt: Due to the Delay is namely a deliberate separation of the unpressurized state flat contiguous areas the membrane is no longer required. The safe Evacuation of the membrane and filling of the gas volume for example with helium is therefore easy and reliable possible.

The order of assembly can be as follows: First become the individual sections ("segments") of the membrane superimposed and in a welding device "Stacked". After closing the welding device is whose interior evacuated and with filling gas, for example with helium, filled with a desired pressure. In this Phase is through the warped membrane sections Ensure that the filling gas is safe in all cavities flows. Then the individual sections pressed together and welded together.

In another advantageous embodiment of the Device according to the invention comprises the membrane at least one bead section and at least one Bellows. This allows the combination of Advantages of both versions.

Furthermore, it is preferred if the membrane at its radial outer edge has a fastening portion, which extends approximately parallel to the central axis and on the Housing is attached. In this way, the entire Inner diameter of the housing used hydraulically effective be, which minimizes the required space and the Costs lowers.

It is possible that the device a Clamping device comprising the attachment portion acted upon radially against the housing. The clamping device may be formed, for example, as a clamping ring. By it relieves the attachment of the membrane to the housing.

drawing

Figur 1

eine schematische Darstellung eines Kraftstoffsystems einer Brennkraftmaschine mit einer Kraftstoffpumpe und einer dort vorhandenen Vorrichtung zum Dämpfen von Druckpulsationen;

Figur 2

einen Schnitt durch ein erstes Ausführungsbeispiel der Vorrichtung zum Dämpfen von Druckpulsationen von Figur 1;

Figur 3

ein Detail III der Vorrichtung zum Dämpfen von Druckpulsationen von Figur 2;

Figur 4

einen Schnitt durch ein zweites Ausführungsbeispiel der Vorrichtung zum Dämpfen von Druckpulsationen von Figur 1;

Figur 5

ein Detail V der Vorrichtung zum Dämpfen von Druckpulsationen von Figur 4;

Figur 6

einen schematischen Schnitt durch eine Membran der Vorrichtung zum Dämpfen von Druckpulsationen von Figur 4;

Figur 7

einen Schnitt durch eine Kraftstoffpumpe mit einem dritten Ausführungsbeispiel einer Vorrichtung zum Dämpfen von Druckpulsationen;

Figur 8

einen Schnitt durch einen Bereich der Kraftstoffpumpe von Figur 7 mit einem vierten Ausführungsbeispiel einer Vorrichtung zum Dämpfen von Druckpulsationen;

Figur 9

einen Schnitt durch ein fünftes und ein sechstes Ausführungsbeispiel einer Vorrichtung zum Dämpfen von Druckpulsationen;

Figur 10

einen Schnitt durch ein siebtes Ausführungsbeispiel einer Vorrichtung zum Dämpfen von Druckpulsationen;

Figur 11

einen Schnitt durch ein achtes Ausführungsbeispiel einer Vorrichtung zum Dämpfen von Druckpulsationen;

Figur 12

einen Schnitt durch ein neuntes Ausführungsbeispiel einer Vorrichtung zum Dämpfen von Druckpulsationen;

Figur 13

einen Schnitt durch ein zehntes Ausführungsbeispiel einer Vorrichtung zum Dämpfen von Druckpulsationen; und

Figur 14

einen Teilschnitt durch ein elftes und ein zwölftes Ausführungsbeispiel einer Vorrichtung zum Dämpfen von Druckpulsationen.

Hereinafter, particularly preferred embodiments of the present invention will be explained in detail with reference to the accompanying drawings. In the drawing show:

FIG. 1

a schematic representation of a fuel system of an internal combustion engine having a fuel pump and a device there for damping pressure pulsations;

FIG. 2

a section through a first embodiment of the device for damping pressure pulsations of Figure 1;

FIG. 3

a detail III of the device for damping pressure pulsations of Figure 2;

FIG. 4

a section through a second embodiment of the device for damping pressure pulsations of Figure 1;

FIG. 5

a detail V of the device for damping pressure pulsations of Figure 4;

FIG. 6

a schematic section through a membrane of the device for damping pressure pulsations of Figure 4;

FIG. 7

a section through a fuel pump with a third embodiment of a device for damping pressure pulsations;

FIG. 8

a section through a portion of the fuel pump of Figure 7 with a fourth embodiment of a device for damping pressure pulsations;

FIG. 9

a section through a fifth and a sixth embodiment of a device for damping pressure pulsations;

FIG. 10

a section through a seventh embodiment of an apparatus for damping pressure pulsations;

FIG. 11

a section through an eighth embodiment of a device for damping pressure pulsations;

FIG. 12

a section through a ninth embodiment of a device for damping pressure pulsations;

FIG. 13

a section through a tenth embodiment of a device for damping pressure pulsations; and

FIG. 14

a partial section through an eleventh and a twelfth embodiment of a device for damping pressure pulsations.

Description of the embodiments

In Figure 1, a fuel system carries a Internal combustion engine as a whole the reference numeral 10. Die Internal combustion engine itself is not shown in detail.

The fuel system 10 includes a fuel tank 12, from which an electric fuel pump 14 the Fuel in a low pressure fuel line 16 promotes. The low pressure fuel line 16 leads to a high pressure fuel pump 18, which symbolically dash-dotted lines is shown.

The high-pressure fuel pump 18 comprises a delivery chamber 20, of a piston, not shown in Figure 1 is limited. The piston will not work either way shown drive shaft in a reciprocating motion added. The drive shaft in turn will turn from the turn not shown camshaft of the internal combustion engine driven. The high pressure fuel pump 18 includes Further, an inlet valve 22, which serves as a check valve is trained. Furthermore, an outlet valve 24 is present, which is also formed by a check valve.

The high pressure fuel pump 18 compresses the fuel at a very high pressure and pump into a fuel rail 26 ("Rail"). In this is the fuel stored under high pressure. To the fuel manifold 26 are multiple fuel injectors 28 connected. These inject the Fuel directly in each associated combustion chambers 30 on.

To the flow rate of the high pressure fuel pump 18th regardless of the speed of the drive shaft to adjust can, a quantity control valve 32 is provided. This is actuated by a magnetic actuator 33, which in turn controlled by a control and device, not shown becomes. The quantity control valve 32 is designed such that during a delivery stroke of the high-pressure fuel pump 18th the inlet valve 22 can be forcibly opened. As a result, the standing under pressure in the delivery chamber 20 Fuel not in the fuel rail 26, but back into the low pressure fuel line 16 promoted. The corresponding switching position of Quantity control valve 32 is designated 34.

The thereby in the low-pressure fuel line 16 initiated pressure pulsations are from a device damped to dampen pressure pulsations. This wears in Figure 1, the reference numeral 36 and will be briefly as Termed "pressure damper". The pressure damper 36 is constructed as follows (see Figures 2 and 3):

The pressure damper 36 comprises a housing with a lower part 38 and an upper part 40. The lower part 38 has in the in Figure 2 shown cut mushroom-shaped, so it is substantially rotationally symmetric with a central axis 41. It comprises an installation section 42 with an in this centrally introduced inlet channel 43 and a overall plate-shaped and in plan view circular bottom portion 44, the overall level in is approximately at a right angle to the central axis 41. The Top 40 of the housing is also plate-shaped and in the plan view formed circular.

Between the bottom portion 44 of the lower part 38 of the Housing and the upper part 40 of the housing is a annular spacer 46 is arranged. He is over Welds 48a and 48b firmly on the one hand with the Bottom portion 44 of the lower part 38 of the housing and on the other hand welded to the upper part 40 of the housing. At one on the spacer 46 radially inwardly extending annular holding portion 52 are two in total in plan view circular membranes 54a and 54b attached. The attachment is made by circulating Welds 57a and 57b at the outermost edge of the membranes 54a and 54b (see Figure 3). The two membranes 54a and 54b are thin-walled and made of metal, preferably made of Stainless steel.

Between the upper diaphragm 54a and the lower diaphragm 54b and the spacer 46 is a gas volume 58 locked in. The gas is passed through a channel 60 introduced in the annular spacer 46th is present (see Figure 2). After the introduction of the Gas in the volume 58 between the two membranes 54a a and 54b, the channel 60 is closed by a ball 62. The entire area between the bottom portion 44, the Upper part 40 of the housing, and the spacer 46 forms a working space 66. The gas volume 58 is thus within the working space 66 is arranged.

Between the bottom portion 44 of the lower part 38 of the Housing and the lower membrane 54b is a first Fluid region 64 of the working space 66 is formed. Between the Top 40 of the housing and the upper membrane 54a is a second fluid region 68 of the working space 66 is formed. Both Fluid areas 64 and 68 may pass through a channel 70 in FIG annular spacers 46 communicate with each other.

The two membranes 54a and 54b are constructed identically (For reasons of clarity, in FIG the upper membrane 54a has all reference numerals inscribed): An their radially outer edge they have a radial extending holding portion 72, with which they on annular spacers 54b are welded. from Holding portion 72 of the membrane bends a spring portion 74th at an angle of about 80 °. The spring portion 74 thus runs approximately in the axial direction. To the Spring section 74 is again a radially extending Bead portion 76 integrally formed. This one stands out a plurality of extending beads 78. The beads 78 run concentrically around the central axis 41 of the Pressure damper 36. A central area of the two Diaphragms 54a and 54b are flat. Of the corresponding area at the diaphragm 54a is called Stopper portion 80a denotes the corresponding area on the membrane 54b as counter-surface 80b (see Figure 2).

The pressure damper 36 operates as follows:

Via the inlet channel 43 in the installation section 42 communicates the bottom in Figures 2 and 3 fluid area 64 (the terms "below" and "above" are always below based on the figures; the pressure damper can basically arbitrarily arranged in the room) of the Working space 66 with the low pressure fuel line 16. Via the channel 70, the upper fluid region 68 communicates the working space 66 in turn with the lower fluid area 64. Within the workroom 66 is that of the two Membranes 54a and 54b and the annular spacer 46 limited gas volume 58 available. This is in the Hibernation of the fuel system 10 under a light Overpressure to the outside atmosphere. Through this Overpressure, the bead portion 76 and the Stopper portion 80a and the mating surface 80b of the two Membranes 54a and 54b slightly bulging outwards.

The distance between the two membranes 54a and 54b and the adjacent to them sections 54a and 40 of the Housing is so big that even when at rest, so with pressureless fuel system, a touch of the two Membranes 54a and 54b with the corresponding sections 40th and 44 of the housing is excluded. Such Limitation of the "stroke" of the membranes is due to the Use of metal as membrane material possible.

The distance between the membranes 54 a and 54 b from the housing 40 or 44 is chosen so that at a system pressure for example, less than 100 kPa in case of pressure undershoot the membranes 54a and 54b the housing 40th or do not touch 44. This is the damping function of Pressure damper 36 also still in this Betriebsbeziehungsweise Guaranteed pressure range.

When the fuel system 10 is in operation, the electric fuel pump 14 so with a specific Pressure promotes the two membranes 54a and 54b moved towards each other. The pressure in the gas volume 58 on the one hand and the rigidity of the two membranes 54a and 54b are chosen so that at normal operating pressure in the low-pressure fuel line 16, that is approximately between 0.5 and 8 bar, a touch of the two membranes 54a and 54b does not take place with each other. Pressure fluctuations can thus in this normal operating range of the Fuel system 10 by a corresponding movement of the both membranes 54a and 54b and a compression of the Gas volume 58 easily recorded and thereby be steamed.

In the event of an overload in the low-pressure fuel line 16, For example, if the pressure rises above 10 bar, comes the stopper portion 80a of the diaphragm 54a and the Counter surface 80b on the membrane 54b together in Appendix. The two membranes 54a and 54b can not move on more, leaving an overload of the two Membranes 54a and 54b can be excluded. In order to a clean system of the two membranes 54a and 54b in Case of overload in the low-pressure fuel line 16 is ensured, the stopper portion 80 a and the counter surface 80b machined plan or spherical.

In addition to the pressure of the gas volume 58, which between the both membranes 54a and 54b is included, the Characteristic of the pressure damper 36 also by the height of the annular spacer 46 are influenced. These Height in particular has an influence on the pressure at which the two membranes 54a and 54b abutting each other come.

Furthermore, by a suitable design of the Inner geometry of the holding portion 52 (for example the position 53 in Figure 3), the internal volume also targeted be downsized. This can increase the effectiveness of the enclosed gas volume 58 formed air spring be further increased.

The shape of the beads 78 and their number plays a essential role for the properties of the pressure damper 36. For a membrane with a diameter of 30 - 60 mm and a wall thickness of 0.2 - 1.0 mm has a number from three to six beads with different bead heights proved to be advantageous. The bead height can be vary between +/- 0.15 and 2 mm. The bead can thereby be circular, sinusoidal or spline-shaped.

In this way can also be an unbalanced Spring stiffness at a load of the two membranes 54a and 54b in Figures 2 and 3 from below or from above be achieved. This makes it possible, in the usual Operating pressure range of the fuel system or the Low-pressure fuel line 16 a comparatively low stiffness with constant spring constant too but rarely used Operating areas, for example. At very low pressure in the Low-pressure fuel line 16 or at a there Ruling very high pressure, higher rigidity of the Membranes 54a and 54b is realized.

By the shape of the beads 78 and by the design of the Spring section 74 is achieved that the maximum Stresses not at the outermost edge of the two membranes 54a and 54b, but about the diameter of the two Membranes 54a and 54b are largely evenly distributed.

Reference is now made to Figures 4 and 5 and 6. In this is a second embodiment of a Pressure damper 36 shown. In doing so, carry such areas and elements which have equivalent functions to areas and elements of the illustrated in Figures 2 and 3 Embodiment, have the same reference numerals. They are not explained again in detail.

A major difference between the two Embodiments is that in which in the Figures 4 and 5 illustrated pressure damper no Spacer longer exists. Instead, that's it Upper part 40 and the bottom portion 44 of the housing directly welded together. The corresponding weld bears the reference numeral 48. Accordingly, the both holding portions 72a and 72b of the two membranes 54a and 54b directly welded together (weld 57).

Beyond that, they are somewhat radial at a position inward of the weld 57, with which the two Membranes 54a and 54b gas-tight welded together are of an upper clamping ring 82 and a lower Clamping ring 84, the upper part 40 and den Bottom portion 44 of the housing are formed, jammed against each other. As a result, the weld, which the two membranes 54a and 54b with each other connects, relieved of mechanical loads.

One shown in Figure 5 only dashed lines Fluid connection 70, which by regions breakthroughs is formed in the clamping rings 82 and 84, the two fluid areas 64 and 68 of the working space 66 fluidly connected. The breakthroughs 70 must be chosen so that the two membranes 54a and 54b are charged approximately the same.

FIG. 6 shows the lower membrane 54b schematically detail. With A, the depth of the membrane 54b denotes, it corresponds to the maximum possible stroke. B denotes a transition region, and C the height of the Sinking of the membrane 54b.

In Figure 7 is a partial section through a Fuel pump shown as high pressure fuel pump 18, for example, in that in Figure 1 shown fuel system 10 is used. you recognizes a cylinder housing 92 with a piston 88, which limits the delivery chamber 20. The quantity control valve 32 can be seen in the upper region of the fuel pump 18. The outlet valve 24 is located in the left area. The Inlet valve 22 is a spring-loaded plate valve formed, which of a plunger (without reference number) the quantity control valve 32 during a delivery stroke of the Forced piston 88 forced into an open position can be.

Coaxial with a cylinder center axis 90 is in the outer Limiting surface of the cylinder housing 92 a circumferential Level 94 incorporated. About this is a housing sleeve 96th postponed. By the revolving stage 94 and the Housing sleeve 96 is a to the cylinder center axis 90th circumferential annular space 66 created. This communicates to the one via a channel 100 with a low pressure inlet 102 the fuel pump 18. On the other hand he communicates via a channel 104 having a pressure relief groove 106, which in a cylinder bore 108 in which the piston 88 is guided is, exists.

In the annular space 66 are two annular circumferential Membranes 54a and 54b arranged. Their outer edges are via welds 57a to 57d on the one hand with the Cylinder housing 92 and the other with the housing sleeve 96th welded. As a result, two separate Gas volumes created 58a and 58b. Between them is one Fluid region 64 of the working space 66 is present, which in particular via the channel 100 with the low pressure inlet 102 communicates. The annulus 66 and the gas volumes 58a and 58b form in this way a pressure damper 36, which is coaxial with the cylinder center axis 90 of the high-pressure fuel pump 18 is arranged.

In Figure 8 is a modified embodiment of a such annular pressure damper 36 shown. there carry such elements and areas, which are equivalent Functions to elements and areas of the in the figures 7 have shown pressure damper 36, the same Reference numerals. They are not explained again in detail.

The pressure damper 36, which is shown in FIG. 8, includes a flattened metal tube 54, which on the Ends gas-tight welded. Its interior forms Gas volume 58. The metal tube 54a is in the working space 66th spiral and helical coaxial with the cylinder center axis 90 wound. This is one thing relative to the housing sleeve 96 and the other to the in Figure 8 upper and lower faces of the working space 66 under a bias and is thereby fixed.

FIG. 9 shows a further variant of a pressure damper 36 shown. It applies here and in all subsequent Figures that have such elements and areas which Equivalent functions to elements and areas that already related to previous ones Figures have been explained, the same reference numerals wear. Normally they will not be detailed again explained.

The pressure damper 36 shown is in the left half Figure 9 designed differently than on the right half. Both devices 36 have in common that they only over have a single membrane 54. This is in the range its holding portion 72 in FIG. 57 with the upper part 40 of FIG Housing welded. Unlike the example in the FIGS. 2 and 3 have the membrane shown in FIG Membrane 54 a bellows portion 110, which between the bead portion 76 and the holding portion 72 are arranged is composed of individual segments 110a to 110d is. This bellows portion 110 allows a comparatively large volume change of the membrane 54 and the housing 40 trapped gas volume 58th

The gas volume 58 is thereby reduced overall, that between the diaphragm 54 and the upper part 40 of the Housing a filler 112 on the upper part 40 of the housing is attached. In the left half of Figure 9 extends a stopper portion 80a from the bead portion 76 of Membrane 54 to the lower part 38 of the housing out, whereas in the right half of FIG. 9 the Stopper portion 80 a to the filling body 112 extends. ever after either the filler 112 or the acts Lower part 38 of the housing as a counter surface 80 b for the Stopper portion 80a.

The gas volume 58 enclosed by the membrane 54 is filled with helium. This is under an overpressure, which is about half of the maximum in operation occurring overpressure, minus that Pressure increase, which by the compression of the membrane 54 is caused. This is for the membrane 54 a used magnetic metal material. This affects the Pressure damper 36 similar to a "dust catcher", because by they become magnetic debris from the fluid intercepted and their distribution in the fluid system 10th prevented.

Furthermore, for the production of the particular Faltenbalgabschnitts 110 of the membrane 54 a strip material used in which residual stresses are present, which a flat distortion of the individual segments 110a, 110b, 110c, and 110d lead. This causes that during the Production of the bellows section 110 the individual Segments 110a to 110d never lie so close together that an evacuation of the air and filling with helium not reliable possible. A conceivable procedure at the manufacture of the bellows portion 110 is as follows:

First, the individual segments 110a to 110d of the Bellows section 110 in a welding device (not shown) stacked. Then the welding device closed and evacuated their interior. Then the Interior of the welding device filled with helium up to a desired internal pressure. By the one default having portions 110a to 110d of Bellows section 110 ensures that even in the corresponding cavities reliably protect the helium can flow in. Now, the individual segments 110a to 110d compressed and welded together in 114 (for clarity, this reference number is only at one point on the left side of FIG. 9 entered).

An alternative to this is shown in FIG. The in Figure 10 shown pressure damper 36 differs from the shown in Figure 9 in that instead of a separate packing 112 in the upper part 40 of the housing Deep-drawn section 112 is present which on the one hand the trapped gas volume 58 reduced and on the other hand has the counter surface 80b, the with the abutment portion 80a of the diaphragm 54 together acts.

FIG. 11 again shows an embodiment in which a separate packing 112 is present, which however not hollow, but solid and beyond in a stopper portion 80a of the diaphragm 54 facing region 116 has a smaller diameter having. Thus, the contour of the filling body 112 of FIG 11 something adapted to the contour of the diaphragm 54, so that the corresponding gas volume 58 is particularly low.

FIG. 12 shows an embodiment in which two diaphragms 54a and 54b are present, respectively For example, the embodiment of a shown in Figure 4 Pressure damper 36. In contrast to Figure 4 is in the in Figure 12 shown embodiment for each membrane 54a and 54b, there is a bellows portion 110 which However, it is simpler than that of FIGS. 9 to 11. The pressure damper shown in FIG has - analogous to that shown in Figures 4 and 5 - upper and lower clamping rings 82 and 84, which, however, in FIG 12 are shown only schematically. Through this, the hydraulically effective surface of the membranes 54a and 54b maximizes, resulting in a reduction of the overall size the pressure damper 36 can be used. The clamping rings 82 and 84 are but spring sections 118 and 120 on Upper part 40 and supported on the lower part 38 of the housing. In this way, manufacturing tolerances of the membranes 54a and 54b.

Between the two membranes 54a and 54b is a disc-shaped retaining ring 122 jammed, the one central Opening 124 has. In this is a two-piece Packing 112 inserted, and the retaining ring 122 is between the two halves 112a and 112b of the packing 112 jammed. Alternatively, it is also possible that in the Packing 112 is provided with a circumferential groove in the the edge of the opening 124 of the retaining ring 122 engages. Also an integral embodiment of the retaining ring 122 with the Packing 112 is conceivable.

Yet another variant of a pressure damper 36 is in FIG. 13. In this pressure damper 36 is no Fillers present, making this device similar to the one constructed as shown in Figs. 4 and 5 is constructed. The differences relate in particular to the clamping rings 82 and 84, with which the membranes 54a and 54b on the housing 40th and 38 are held: the clamping rings 82 and 84 face projecting spring portions, wherein a spring portion 118a and 120a, the membranes 54a and 54b in Figure 13 in positioned in the vertical direction, whereas a Spring section 118b and 120b, the two membranes 54 and 56 positioned in Figure 13 in the horizontal direction or centered.

The spring sections 118a and 120a are separated by individual radially inwardly facing bracket of the two clamping rings 82nd and 84 formed in the one shown in FIG Mounting position against the upper part 40 and the lower part 38 of the Housing are biased. The spring sections 118b or In turn, 120b are separated by radially outward acting strap formed on the inner surface of the upper part 40 of the housing 40 bear or against them are biased.

In Figure 14 is a modified again Embodiment of a pressure damper 36 shown. at this is at the radially outer edge of the bead portion 76th a tubular attachment portion 122 is provided which is approximately parallel to the central axis 41 of the Pressure damper 36 extends and in 57 with its edge the housing 40 is welded. Ultimately, then is the Membrane 54 attached directly to the housing 40, what else spares required additional constructions. additionally The pressure damper 36 in FIG. 14 has a clamping ring 124 on which the fastening portion 122 from radially inward forth against the housing 40 presses. This will be the Weld 57 mechanically relieved. The radial maximum external weld 57 allows the use of the total inner diameter of the housing 40 as a hydraulic effective diameter. This lowers the manufacturing costs.

The gas volume 58 can either in the manufacture of the Weld 57 can be set up (welding in one Pressure chamber). Or the work space 66 is retroactive filled through the opening 60, which then through the element 62 is closed. The latter can, for example, with the Housing 40 are welded. As with the Embodiments of Figures 9 to 11 is also in the shown in Figure 14 the pressure damper 36, the gas volume 58th formed between the diaphragm 54 and the housing 40. This leads to a minimization of the required Installation space.

Claims (33)

Device (36) for damping pressure pulsations in a fluid system (16), in particular in a fuel system of an internal combustion engine, with a housing (38, 40) and with at least one working chamber (66) communicating with the fluid system (16) at least in regions, characterized in that within the working space (66) at least one through a membrane (54) sealed gas volume (58) is present. Device (36) according to one of the preceding claims, characterized in that the membrane (54) is made of metal. Device (36) according to claim 2, characterized in that the membrane is bounded by a thin-walled and at its ends gas-tight closed metal tube (54). Device (36) according to any one of the preceding claims, characterized in that at least one outer wall of the working space is also formed as a membrane. Device (36) according to any one of the preceding claims, characterized in that the enclosed gas volume (58) at a standard external pressure has a defined pressure, preferably an overpressure. Device (36) according to claim 5, characterized in that the gas volume (58) has a closable opening (60) through which the pressure can be adjusted. Device (36) according to one of the preceding claims, characterized in that the membrane (54) has at least one bead (78). Device (36) according to claim 7, characterized in that the membrane (54) has a plurality of beads (78), which have different height and / or a different course and / or a different cross-section. Device (36) according to one of the preceding claims, characterized in that the membrane (54a) has at least one abutment portion (80a) which comes into abutment with a counter-surface (80b) at a maximum deflection of the membrane (54). Device (36) according to claim 9, characterized in that the mating surface (80b) is formed on the housing (40), on a separate stop member (112), and / or on another diaphragm (54b). Device (36) according to one of the preceding claims, characterized in that the enclosed gas volume (58) is reduced by a filling area (112). Device (36) according to one of the preceding claims, characterized in that the gas volume (58) is delimited by at least two membranes (54a, 54b) which are clamped in the region of their edges (82, 84). Device (36) according to claim 12, characterized in that the membranes (54a, 54b) are substantially parallel in their entirety. Device (36) according to claim 13 in conjunction with claim 10, characterized in that the gas volume (58) between the two membranes (54a, 54b) is formed and the two membranes (54a, 54b) respectively at least one stop surface (80a) and . Have a mating surface (80b), which touch at a maximum deflection of the two membranes (54a, 54b). Device (36) according to one of claims 12 to 14, characterized in that the edges of the two membranes (54a, 54b) are tightly connected to each other and clamped radially inwards from the sealing line (57) (82, 84). Device (36) according to claim 15, characterized in that the clamping (82, 84) has a structural elasticity (118, 120). Device (36) according to one of claims 12 to 16, characterized in that the two membranes (54a, 54b) are identical. Device (36) according to one of claims 12 to 17, characterized in that the working space (66) is divided by the two membranes (54a, 54b) into two regions (64, 68) which communicate with each other by a fluid connection (70) , Device (36) according to one of Claims 12 to 18, characterized in that an annular spacer (46) is present between the two diaphragms (54a, 54b). Device (36) according to claims 17 and 19, characterized in that the fluid connection (70) is formed in the spacer. Device (36) according to one of the preceding claims, characterized in that it is integrated in a housing (92) of a fuel pump (18). Device (36) according to one of the preceding claims, characterized in that the working space comprises an annular space (66) and the gas volume (58) is annular. Device (36) according to claims 20 and 21, characterized in that the working chamber (66) and the gas volume (58) are arranged in or on a cylinder (92) of a fuel pump (18) at least approximately coaxially with the cylinder axis (90) , Device (36) according to one of claims 21 or 22, characterized in that the gas volume (58) is arranged in the manner of a spiral within the annular space (66), wherein the spiral (58) and the annular space (66) at least approximately coaxial. Device (36) according to claim 23, characterized in that the spiral gas volume (58) is biased against the outer wall of the working space (66). Device (36) according to one of claims 23 or 24, characterized in that the helical gas volume (58) runs helically in the axial direction of the working chamber (66). Apparatus (36) according to claim 25, characterized in that the spiral and helical gas volume (58) is biased in the axial direction against the front ends of the working space (66). Device (36) according to one of the preceding claims, characterized in that the gas volume (58) is filled with helium. Device (36) according to one of the preceding claims, characterized in that the membrane (54) and / or the housing are at least partially magnetic. Device (36) according to one of the preceding claims, characterized in that the membrane (36) is at least partially made of a strip material which has residual stresses. Device (36) according to one of the preceding claims, characterized in that the membrane (54) comprises at least one bead portion (76) and at least one bellows portion (110). Device (36) according to one of the preceding claims, characterized in that the membrane (54) has at its radially outer edge a fastening portion (122) which extends approximately parallel to the central axis (41) and fixed to the housing (40) is. Device (36) according to claim 32, characterized in that it comprises a clamping device (124), which acts on the mounting portion (122) radially against the housing (40).

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