DE10327408A1 - Device for damping pressure pulsations in a fluid system, in particular in a fuel system of an internal combustion engine - Google Patents

Abstract

A device (36) is proposed which serves to dampen pressure pulsations in a fluid system (16). It comprises a housing (38, 40) and at least one work space (66) which communicates with the fluid system (16). At least one gas volume (58) sealed by a membrane (54a, 54b) is present within the working space (66).

Description

State of technology

The invention relates to a device for steaming 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 work area, which at least in some areas communicates with the fluid system.

Such a device is from the DE 195 39 885 A1 known. A fuel system of an internal combustion engine with direct fuel injection is shown there. The fuel is conveyed from a pre-feed pump to a high-pressure piston pump, which compresses the fuel to a very high pressure. The fuel passes from the high-pressure piston pump into a fuel collecting line (“rail”). The high-pressure piston pump is driven by a camshaft of the internal combustion engine. In order to be able to adjust the delivery rate of the high-pressure piston pump independently of the speed of the camshaft, a volume control valve is provided. This allows the delivery chamber of the high-pressure piston pump to be briefly connected to the area of the fuel system located between the electric pre-delivery pump and the high-pressure fuel pump during a delivery stroke.

This will, however, be significant Pressure pulsations initiated in this area of the fuel system. To dampen this, there is a pressure damper intended. This consists of a housing and a piston, which is biased by a spring.

One is also known from the market Pressure damper, which works with a rubber membrane biased by a spring. So with unpressurized systems (e.g. when the internal combustion engine is switched off) the rubber membrane is not stretched improperly over time is a Stop available, on which the membrane is supported at low pressure.

The one from the DE 195 39 885 A1 known fuel system, the pressure between the prefeed pump and the high-pressure piston pump is approximately constant. In modern fuel systems, however, this pressure can be variable. Typically, it is between 0.5 and 8 bar, with overload protection up to approximately 10 to 12 bar. If the known pressure damper, which has a rubber membrane, is used in such a fuel system, there is a risk that the rubber membrane will strike the stop at a low system pressure, for example of 0.5 bar and the superimposed pressure pulsations. As a result, the damping effect of the pressure damper is weakened and damage to the rubber membrane can occur. The one from the DE 195 39 885 A1 Known pressure dampers with a piston and a spring in turn would have to be very large when used in such a fuel system with a variable admission pressure.

The present invention therefore has the task of further developing a device of the type mentioned at the outset, that they are used in a variable form fuel system can be, but it is small and has a long life.

This task is done with a device of the type mentioned in that solved within the work space at least one gas volume sealed by a membrane is available.

Advantages of invention

By using a closed The compressibility of gases can be exploited for this purpose be the for the damping of Ensure the necessary elastic movement of the membrane due to pressure pulsations. No mechanical elements act on the membrane, which significantly increases their lifespan and the risk of damage reduced. About that In addition, such a gas volume can be of almost any geometric Form can be realized. So it can be very space-saving in the fluid system be accommodated. Another advantage of the device according to the invention is that there is no need for a leakage line, which further simplifies the structure of the fuel system.

Advantageous further developments of Invention are in subclaims specified.

In a first training course suggested that the membrane be made of metal. Such a membrane has various advantages: On the one hand, such a membrane is compared to conventional ones Gases and also opposite Fluids very dense. The high level of sealing plays here in particular of metal membranes HC emissions play a positive role. On the other hand occurs with a metal membrane even with low pushers :, For example, with the internal combustion engine switched off, no overexpansion over time on so that a damper device can be used with a metal membrane in a fluid system, which one in a big Has variable fluid pressure range.

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

If at least one outer wall of the Ar beitsraums is also designed as a membrane, you get an additional hydraulically effective area in a minimal space. The effectiveness of the device according to the invention is hereby significantly increased again, while at the same time taking up little space.

It is particularly advantageous if the enclosed gas volume at a standard external pressure (e.g. 1013 hPa) has a defined pressure, preferably an overpressure. With such a defined pressure, the "spring stiffness" can be set. Usually becomes an overpressure in the enclosed gas volume compared to the external pressure chosen because the entire possible tension range (train and pressure) of the membrane material can be exploited.

A negative pressure is also conceivable or standard pressure. Such an internal overpressure is preferred selected which in about half of the maximum operating pressure, less the increase in pressure caused by the compression of the component, equivalent.

This can also be done by minimizing the trapped. Gas volume the effectiveness of the gas volume be optimized. Such a minimization means that higher Realized spring stiffness. This can make the membrane thinner and the stresses in the membrane material can be minimized. Besides, will the device works without any stops in the entire working area allows. Furthermore, the burden is about reduced the entire operating range 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 be interpreted.

The gas volume can have a closable opening through which the pressure can be adjusted. This facilitates production of the gas volume. Otherwise you would have to the production is done even at a certain pressure.

That configuration of the device according to the invention, in which the membrane has at least one bead. By a such beading can the spring properties of the membrane itself and also its strength properties essential to be influenced. With a bead, the membrane can be optimal can be adapted to the individual requirements of the fluid system. Above all, the damper have even more damping volume with a comparable construction volume, or alternatively can be built smaller. The beads can be different Height and / or a different course and / or a different one Cross section.

This way you can get an unbalanced Achieve spring stiffness of the membrane depending on the direction of loading.

This allows, for example, in the main work area the pressure damper device a targeted, for example a largely constant and rather soft spring constant the membrane can be reached. In rarely used operating areas however, a higher one Stiffness can be realized. That way you can't do one linear or only piecewise achieve linear spring characteristic. Ultimately, this becomes a optimal damping effect in the entire operating range of the fluid system at the same time as low Installation space reached.

The beads can also be shaped that the maximum stress does not occur at the edge of the membrane, and the mechanical stresses over the area the membrane is distributed as evenly as possible are. Furthermore, by appropriate membrane design the entire range of materials in the tensile and compressive stress range be used.

It can also be provided that the membrane has at least one stop area, which at a maximum deflection of the membrane with a counter surface in contact comes. The maximum deflection is chosen so that damage on the membrane, for example a plastic deformation, straight can still be avoided. This device is therefore at least in a certain area "overload safe", i.e. it shows even with overloads another damping function, without being damaged to become.

In further training, it is proposed that the counter surface on the housing, on a separate stop part and / or on another membrane is trained. The overload protection can So realized in various very simple and inexpensive ways become. The stop surface on the housing can be made, for example, by deep drawing, which is very is simple and inexpensive. A separate stop part is also inexpensive, being for a. same damper Different stop parts can be provided, so that the same device can be easily adapted to different operating conditions. The stop surface another membrane saves space.

In further training also suggested that the enclosed gas volume by a filling area is reduced. This fill area can also be formed by the stop part (this then acts as a "filler") or a housing section. As mentioned above, can reduce the spring stiffness by reducing the gas volume Device increased become. As a result, the membrane can be thinner, which is a good dynamic and results in a small size.

An advantageous embodiment of the device according to the invention is that the gas volume is limited by at least two membranes which are clamped in the area of their edges are. Such a pressure damper is comparatively flat. All the more so if the membranes are essentially parallel. In principle, it is of course conceivable that the gas volume is introduced into the space between the two membranes when they are joined together, so that a filling opening can be dispensed with.

One is also proposed Device in which the gas volume between the two membranes is formed and the two membranes each have at least one stop surface or one counter surface have, which at a maximum deflection of the two Touch the membrane. This takes advantage of that in the case of a high pressure, the two membrane surfaces meet to move. When they come into contact with each other, they support yourself with the stop surfaces mutually. These stop faces can plan accomplished to ensure that the membranes are in perfect contact with one another. An overload the membranes at too high pressure are thereby reliably excluded, without the need for a separate stop.

Possible is also that the edges of the two membranes tightly connected to each other and radially inward from the sealing line are clamped. Especially when the connection through a weld is done by this embodiment of the device according to the invention prevents the welds from additional endure mechanical forces have to. The sealing connection is only used for sealing and does not have to take on other tasks and can therefore meet particularly high tightness requirements. For evaluation The durability of the pressure damper according to the invention only has to be the membranes be considered yourself.

It is particularly advantageous if the clamping over a constructive elasticity features. This is understood to mean an elasticity that is "constructively desired". For example can use a retaining ring made of a rubber-elastic material or a metal bracket can be used which has a spring section. On the one hand, this becomes a Secure fixation of the membranes achieved, and on the other hand, manufacturing tolerances be balanced. in principle can attack the clamp anywhere on the membrane, especially Cheap is, however, an approach in the middle plane of the two membranes.

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

The installation space of the device according to the invention is particularly small if the working space of the two membranes is in is divided into two fluid areas, which are connected by a fluid connection communicate 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 that connects the two fluid areas of the work area connects together to form in the spacer.

It is particularly advantageous if the device in a housing a fuel pump is integrated. The advantages according to the invention are made there particularly noticeable, since such a fuel pump usually to build very small.

Circulating areas are often used in fuel pumps available, in which shafts or pistons are arranged. In these make can the damping device according to the invention particularly space-saving if the work space comprises an annular space and the gas volume is also annular. It is particularly advantageous if the work space and the Gas volume on a cylinder of a fuel pump at least in are arranged approximately coaxially to the cylinder axis. The pressure damper surrounds with it, so to speak, the cylinder and the piston in it, what additionally still causes noise reduction.

It is also suggested that that Volume of gas is arranged in the manner of a spiral in the annular space, wherein the spiral and the annulus are at least approximately coaxial. Such a spiral results in a large deformation area, the contributes to a particularly effective pulsation damping.

If the spiral gas volume against the outer wall of the work area is prestressed, results without additional Share a fixation of the gas volume in the work area.

The effective area of the gas volume can again elevated when the spiral Gas volume helical runs in the axial direction of the work area.

This in turn becomes the fixation of the gas volume without additional Parts allows if the spiral and helical Gas volume in the axial direction against the front ends of the work area is biased.

Another preferred embodiment the device according to the invention is characterized in that the gas volume is filled with helium. This makes it easier to detect a leak.

In addition, the membrane and / or the housing can be magnetic. Appropriate manufacturing processes (for example mechanical rolling and embossing) create a martensitic structure ("forming martensite") in the material which has magnetic properties. If this magnetic property is deliberately left in the corresponding component, the device can capture magnetic dirt particles present in the fluid and prevent their 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 complex demagnetization of the component is eliminated. Since there are no directly adjacent and relatively movable parts in the device, the trapped dirt particles do not cause any functional damage to the device.

It is also possible that the membrane is made of a strip material which has internal stresses having. Such residual stresses lead to during the forming process a flat Delay so that the material is rejected in the deformed state. This can now be targeted for the Simplification of the manufacture of the membrane can be used, in particular if this has at least one bellows section: Because of the delay is namely a targeted keeping apart of one another in the unpressurized state lying areas of the membrane are no longer required. The safe one Evacuation of the membrane and filling the gas volume, for example with helium, is therefore simple and reliable possible.

The assembly order can be as follows: First the individual sections ("segments") of the membrane are placed on top of each other and "stacked" in a welding device. After closing the welder the interior is evacuated and filled with filling gas, for example with helium, with a desired one Pressure filled. In this phase, the warped membrane sections ensure that the fill gas in all cavities flows safely. Then the individual sections are pressed together and welded together.

In another advantageous embodiment the device according to the invention the membrane comprises at least one bead section and at least one a bellows section. This allows the advantages to be combined both versions.

It is also preferred if the membrane is on its radially outer edge has a fastening section which is approximately parallel extends to the central axis and is attached to the housing. To this The entire inner diameter of the housing can be used hydraulically effectively be what minimizes the space required and the cost lowers.

It is possible that the device Clamping device which comprises the fastening section radially against the housing applied. The tensioning device can be used, for example, as a tension ring be trained. Through them the membrane is attached to the casing relieved.

drawing

The following are particularly preferred exemplary embodiments of the present invention with reference to the accompanying Drawing explained in detail. The drawing shows:

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

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

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

4 one, section through a second embodiment of the device for the damper. of pressure pulsations from 1 ;

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

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

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

8th a section through an area of the fuel pump of 7 with a fourth embodiment of a device for damping pressure pulsations;

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

10 a section through a seventh embodiment of a device for damping pressure pulsations;

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

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

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

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

description of the embodiments

In 1 a fuel system of an internal combustion engine bears the overall reference number 10 , The 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 into a low pressure force fuel line 16 promotes. The low pressure fuel line 16 leads to a high pressure fuel pump 18 , which is shown symbolically in dash-dotted lines.

The high pressure fuel pump 18 includes a funding room 20 by one in 1 Piston not shown is limited. The piston is moved back and forth by a drive shaft, also not shown. The drive shaft in turn is driven by the camshaft of the internal combustion engine, which in turn is not shown. The high pressure fuel pump 18 further includes an inlet valve 22 , which is designed as a return valve. There is also an outlet valve 24 negotiator, which is also formed by a check valve.

The high pressure fuel pump 18 compresses the fuel to a very high pressure and delivers it to a fuel manifold 26 ( "Rail"). The fuel is stored under high pressure. To the fuel rail 26 are multiple fuel injectors 28 connected. These inject the fuel directly into the combustion chambers assigned to them 30 on.

The delivery rate of the high-pressure fuel pump 18 To be able to adjust independently of the speed of the drive shaft is a quantity control valve 32 intended. This is done by a magnetic actuator 33 actuated, which in turn is controlled by a control and device, not shown. The volume control valve 32 is designed so that during a delivery stroke of the high pressure fuel pump 18 the inlet valve 22 can be opened forcibly. This causes the pressure in the delivery chamber 20 fuel is not in the fuel rail 26 but back into the low pressure fuel line 16 promoted. The corresponding switch position of the volume control valve 32 has the reference symbol 34 ,

This results in the low pressure fuel line 16 initiated pressure pulsations are damped by a device for damping pressure pulsations. This carries in 1 the reference number 36 and is hereinafter referred to as "pressure damper". The pressure damper 36 is structured as follows (cf. 2 and 3 ):
The pressure damper 36 comprises a housing with a lower part 38 and a top 40 , The bottom part 38 has in the in 2 shown section mushroom-shaped shape, so is essentially rotationally symmetrical with a central axis 41 , It includes an installation section 42 with an inflow channel inserted centrally in this 43 and a bottom section that is overall plate-shaped and circular in plan view 44 , whose overall plane is approximately at a right angle to the central axis 41 stands. The top 40 the housing is also plate-shaped and circular in plan view.

Between the bottom section 44 of the lower part 38 of the housing and the upper part 40 the housing is an annular spacer 46 arranged. It's over welds 48a and 48b firmly on the one hand with the bottom section 44 of the lower part 38 of the housing and on the other hand with the upper part 40 of the housing welded. On one yourself on the spacer 46 radially inwardly extending annular holding portion 52 are two membranes that are circular overall in plan view 54a and 54b attached. The attachment is made by all-round weld seams 57a and 57b at the very edge of the membranes 54a and 54b (see. 3 ). The two membranes 54a and 54b are thin-walled and made of metal, preferably stainless steel.

Between the top membrane 54a and the lower membrane 54b and the spacer 46 is a volume of gas 58 locked in. The gas is through a channel 60 introduced the in the annular spacer 46 is present (cf. 2 ). After introducing the gas into the volume 58 between the two membranes 54aa and 54b becomes the channel 60 through a bullet 62 locked. The entire area between the bottom section 44 , the top 40 the housing, and the spacer 46 forms a work space 66 , The gas volume 58 is inside the workspace 66 arranged.

Between the bottom section 44 of the lower part 38 of the housing and the lower membrane 54b is a first fluid area 64 of the work space 66 educated. Between the top 40 of the housing and the upper membrane 54a is a second fluid area 68 of the work space 66 educated. Both fluid areas 64 and 68 can through a channel 70 in the ring-shaped spacer 46 communicate with each other.

The two membranes 54a and 54b are constructed identically (for reasons of clarity, in 3 only for the upper membrane 54a all reference numbers entered): At their radially outer edge they have a radially extending holding section 72 on the ring-shaped spacer 54b are welded. From the holding section 72 the membrane bends a spring section 74 at an angle of approximately 80 °. The spring section 74 thus runs approximately in the axial direction. At the spring section 74 is again a radially extending bead section 76 formed. This is characterized by a plurality of beads 78 out. The beads 78 run concentrically around the central axis 41 of the pressure damper 36 , A central area of the two membranes 54a and 54b is just executed. The corresponding area for the membrane 54a is called the stop section 80a designated, the corresponding area on the membrane 54b as a counter surface 80b (see. 2 ).

The pressure damper 36 works as follows: via the inlet channel 43 in the installation section 42 communicates in the 2 and 3 lower fluid area 64 (The terms "below" and "above" always refer to the figures below; Pressure dampers can basically be arranged anywhere in the room) of the work area 66 with the low pressure fuel line 16 , Over the channel 70 the upper fluid area communicates 68 of the working space 66 in turn, with the lower fluid area 64 , Inside the work space 66 is that from the two membranes 54a and 54b and from the annular spacer 46 limited gas volume 58 available. This is in the idle state of the fuel system 10 under a slight overpressure compared to the outside atmosphere. Due to this overpressure, the bead section 76 and the stop section 80a or the counter surface 80b of the two membranes 54a and 54b bulging outwards somewhat.

The distance between the two membranes 54a and 54b and the sections adjacent to them 54a respectively. 40 However, the housing is so large that even in the idle state, i.e. with the fuel system depressurized, the two membranes come into contact 54a and 54b with the appropriate sections 40 and 44 the housing is excluded. Such a limitation of the "stroke" of the membranes is possible through the use of metal as the membrane material.

The distance of the membranes 54a and 54b from the housing 40 respectively. 44 is selected so that the membranes at a system pressure, for example, less than 100 kPa in the event of a pressure undershoot 54a and 54b the housing 40 respectively. 44 do not touch. This is the damping function of the pressure damper 36 guaranteed even in this operational or pressure range.

If the fuel system 10 is in operation, the electric fuel pump 14 So with a certain pressure, the two membranes 54a and 54b moving towards each other. The pressure in the gas volume 58 on the one hand and the rigidity of both membranes 54a and 54b are selected so that at normal operating pressure in the low-pressure fuel line 16 between 0.5 and 8 bar, a touch of the two membranes 54a and 54b not taking place with each other. Pressure fluctuations can thus occur in this normal operating range of the fuel system 10 by a corresponding movement of the two membranes 54a and 54b and compression of the gas volume 58 can be easily absorbed and thereby dampened.

In the event of an overload in the low-pressure fuel line 16 if the pressure rises above 10 bar, for example, the stop section comes 80a the membrane 54a and the counter surface 80b on the membrane 54b with each other in plant. The two membranes 54a and 54b can therefore no longer move, so that an overload of the two membranes 54a and 54b can be excluded. So that the two membranes fit neatly 54a and 54b in the event of an overload in the low pressure fuel line 16 the stop section is guaranteed 80a and the counter surface 80b machined flat or spherical.

In addition to the pressure of the gas volume 58 which is between the two membranes 54a and 54b included, the characteristic of the pressure damper 36 also by the height of the annular spacer 46 to be influenced. This height particularly affects the pressure at which the two membranes 54a and 54b come into contact with each other.

Furthermore, by a suitable design of the inner geometry of the holding section 52 (for example at the position 53 in 3 ) the internal volume can also be specifically reduced. This can. the effectiveness of the enclosed gas volume 58 formed air spring can be further increased.

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

In this way, an asymmetrical spring stiffness when the two membranes are loaded 54a and 54b in the 2 and 3 can be reached from below or from above. This makes it possible, in the usual operating pressure range of the fuel system or the low-pressure fuel line 16 to achieve a comparatively low stiffness with a constant spring constant, whereas in rarely used operating areas, for example at very low pressure in the low-pressure fuel line 16 or at a very high pressure there, a higher rigidity of the membranes 54a and 54b is realized.

Due to the shape of the beads 78 and by the design of the spring section 74 it is achieved that the maximum stresses are not at the extreme edge of the two membranes 54a and 54b occur, but about the diameter of the two membranes 54a and 54b are largely evenly distributed.

Now on the 4 and 5 such as 6 Referred. In these is a second embodiment of a pressure damper 36 shown. Those areas and elements that have equivalent functions to areas and elements of the 2 and 3 shown embodiment has the same reference numerals. They are not explained in detail again.

A major difference between the two embodiments. is that in the 4 and 5 shown pressure damper is no longer a spacer. Instead are the top 40 and the bottom cut 44 of the housing directly welded together. The corresponding weld has the reference symbol 48 , The two holding sections are also corresponding 72a and 72b of the two membranes 54a and 54b welded directly to one another (weld seam 57 ).

They will also, at a position slightly radially inward from the weld 57 with which the two membranes 54a and 54b are welded together gastight, by an upper clamping ring 82 and a lower clamp ring 84 that to the top 40 or the bottom section 44 of the housing are molded, jammed against each other. As a result, the weld seam, which the two membranes 54a and 54b connected with each other, relieved of mechanical loads.

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

6 shows the lower membrane 54b schematically detailed. With A is the depth of the membrane 54b designated, it corresponds to the maximum possible stroke. B denotes a transition area and C the height of the sinking of the membrane 54b ,

In 7 is a partial section through a fuel pump, as shown as a high-pressure fuel pump 18 for example in the in 1 fuel system shown 10 is used. You can see a cylinder housing 92 with a one piston 88 which is the funding area 20 limited. The volume control valve 32 is in the upper area of the fuel pump 18 recognizable. The exhaust valve 24 is in the left pane. The inlet valve 22 is designed as a spring-loaded plate valve, which is from a tappet (without reference number) of the volume control valve 32 during a delivery stroke of the piston 88 can be forced into an open position.

Coaxial to a central cylinder axis 90 is in the outer boundary surface of the cylinder housing 92 an encircling step 94 incorporated. Over this is a housing sleeve 96 postponed. Through the circumferential step 94 and the housing sleeve 96 becomes a around the cylinder's central axis 90 circumferential annulus 66 created. On the one hand, this communicates via a channel 100 with a low pressure inlet 102 the fuel pump 18 , On the other hand, it communicates via a channel 104 with a pressure relief groove 106 which in a cylinder bore 108 in which the piston 88 is led, is present.

In the annulus 66 are two circular membranes 54a and 54b arranged. The outer edges are welded 57a to 57d on the one hand with the cylinder housing 92 and on the other hand with the housing sleeve 96 welded. This creates two separate gas volumes 58a and 58b created. Between them is a fluid area 64 of the work space 66 available, which in particular via the channel 100 with the low pressure inlet 102 kommniziert. The annulus 66 and the gas volumes 58a and 58b form a pressure damper in this way 36 , which is coaxial to the center axis of the Zviinder 90 the high pressure fuel pump 18 is arranged.

In 8th is a modified embodiment of such an annular pressure damper 36 shown. Such elements and areas, which have equivalent functions to elements and areas of the 7 shown pressure damper 36 have the same reference numerals. They are not explained in detail again.

The pressure damper 36 which in 8th is shown includes a flattened metal tube 54 which is welded gas-tight at the ends. Its interior forms a gas volume 58 , The metal pipe 54a is in the work room 66 spiral and screw-shaped coaxial to the cylinder center axis 90 wound. As a result, it is on the one hand opposite the housing sleeve 96 and on the other hand to those in 8th upper and lower end faces of the work space 66 under tension and is thereby fixed.

In 9 is another variant of a pressure damper 36 shown. It applies here and in all subsequent figures that those elements and areas which have functions equivalent to elements and areas which have already been explained in connection with previous figures have the same reference numerals. They are normally not explained in detail again.

The pressure damper shown 36 is in the left half of the 9 designed differently than on the right half. Both devices 36 common is that they only have a single membrane 54 feature. This is in the area of its holding section 72 in 57 with the top 40 of the housing welded. Unlike for example in the 2 and 3 Membrane has the in 9 membrane shown 54 a bellows section 110 on that between the bead section 76 and the holding section 72 is arranged and made up of individual segments 110a to 110d is constructed. This bellows section 110 enables a comparatively large change in volume of the membrane 54 and the housing 40 enclosed gas volume 58 ,

The gas volume 58 is reduced overall by the fact that between the membrane 54 and the top 40 of the housing a packing 112 on the top 40 the housing is attached. In the left half of the 9 extends a stop portion 80a from the bead section 76 the membrane 54 to the lower part 38 of the housing, whereas in the right half the 9 the stop section 80a to the packing 112 extends. Depending on whether the filler works 112 or the lower part 38 of the housing as a counter surface 80b for the stop section 80a ,

The membrane 54 enclosed gas volume 58 is filled with helium. This is under an overpressure, which corresponds to approximately half of the maximum overpressure occurring during operation, minus that pressure increase, which is caused by the compression of the membrane 54 is caused. This is for the membrane 54 uses a magnetic metal material. As a result, the pressure damper acts 36 similar to a "dust catcher", because magnetic dirt particles are trapped by them and their distribution in the fluid system 10 prevented.

Furthermore, in particular for the manufacture of the bellows section 110 the membrane 54 a strip material is used in which residual stresses are present, which leads to a flat distortion of the individual segments 110a . 110b . 110c , and 110d to lead. This causes that during the manufacture of the bellows section 110 the individual segments 110a to 110d never lie so close together that it is not possible to reliably evacuate the air and fill it with helium. A conceivable procedure in the manufacture of the bellows section 110 is as follows: First, the individual segments 110a to 110d of the bellows section 110 stacked in a welding device (not shown). Then the welding device is closed and its interior is evacuated. Then the interior of the welding device is filled with helium up to a desired internal pressure. Due to the warped sections 110a to 110d of the bellows section 110 it is ensured that the helium can also reliably flow into the corresponding cavities. Now the individual segments 110a to 110d compressed and in 114 welded together (for reasons of clarity, this reference number is only in one place on the left side of the 9 entered).

An alternative to this is in 10 shown. The in 10 shown pressure damper 36 differs from that in 9 shown in that instead of a separate packing 112 in the upper part 40 a section of the housing produced by deep drawing 112 is present, which is the enclosed gas volume 58 reduced and secondly the counter surface 80b has that with the stop portion 80a the membrane 54 together. acts.

11 again shows an embodiment in which a separate filler 112 is present, which, however, is not hollow, but has a solid structure and, moreover, in one of the stop sections 80a the membrane 54 facing area 116 has a smaller diameter. This is the contour of the packing 112 of 11 something to the contour of the membrane 54 adjusted so that the corresponding gas volume 58 is particularly low.

In 12 An embodiment is shown in which two membranes 54a and 54b are available, for example in 4 shown embodiment of a pressure damper 36 , In contrast to 4 is with the in 12 shown embodiment for each membrane 54a and 54b a bellows section 110 available, which is simpler than that of 9 to 11 , The in 12 shown pressure damper - analogous to that in the 4 and 5 shown - upper and lower clamping rings 82 and 84 which, however, in 12 are only shown schematically. This makes the hydraulically effective surface of the membranes 54a and 54b maximized, resulting in a reduction in the overall size of the pressure damper 36 can be used. The clamping rings 82 and 84 but are about spring sections 118 and 120 on the top 40 or on the lower part 38 supported the housing. In this way, manufacturing tolerances of the membranes 54a and 54b be balanced.

Between the two membranes 54a and 54b is a disc-shaped retaining ring 122 jammed of a central opening 124 having. In this is a two-part 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 there is a circumferential groove in which the edge of the opening 124 of the retaining ring 122 intervenes. Also a one-piece version of the retaining ring 122 with the packing 112 is conceivable.

Yet another variant of a pressure damper 36 is in 13 shown. With this pressure damper 36 there is no packing, so that this device is constructed similarly to that which is shown in the 4 and 5 is shown. The differences particularly concern the clamping rings 82 and 84 with which the membranes 54a and 54b on the housing 40 and 38 are held: The clamping rings 82 and 84 have cantilevered spring sections, one spring section 118a respectively. 120a the membranes 54a and 54b in 13 positioned in the vertical direction, whereas a spring section 118b respectively. 120b the two membranes 54 and 56 in 13 positioned or centered in the horizontal direction.

The spring sections 118a and 120a are made by individual, radially inwardly directed brackets of the two clamping rings 82 and 84 formed in the in 13 Installation position shown against the upper part 40 or the lower part 38 of the housing are biased. The spring sections 118b respectively. 120b again are formed by individual radially outwardly acting brackets, which on the inner lateral surface of the upper part 40 of the housing 40 concern or are biased against them.

In 14 is another modified Embodiment of a pressure damper 36 shown. This is at the radially outer edge of the bead section 76 a tubular attachment section 122 available, which is approximately parallel to the central axis 41 of the pressure damper 36 extends and in 57 with his. Edge with the housing 40 is welded. Ultimately, the membrane is 54 directly on the housing 40 attached, which saves the additional structures otherwise required. In addition, the pressure damper 36 in 14 a tension ring 124 on which is the mounting section 122 radially from the inside against the housing 4C suppressed. This will make the weld 57 mechanically relieved. The radially maximum external weld seam 57 allows the use of the entire inside diameter of the housing 40 as a hydraulically effective diameter. This lowers the manufacturing costs.

The gas volume 58 can be done either when making the weld 57 be set up (welding in a pressure chamber). Or the work space 66 is added later through the opening 60 filled which then through the element 62 is closed. The latter can, for example, with the housing 40 be welded. As with the embodiments of the 9 to 11 is also in the 14 shown pressure damper 36 the gas volume 58 between the membrane 54 and the housing 40 educated. This leads to a minimization of the installation space required.

Claims (32)

Contraption ( 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 work area ( 66 ), which is connected at least in some areas with the fluid system ( 16 ) communicates, characterized in that within the work space ( 66 ) at least one through a membrane ( 54 ) tightly sealed gas volume ( 58 ) is available. Contraption ( 36 ) according to one of the preceding claims, characterized in that the membrane ( 54 ) is made of metal. Contraption ( 36 ) according to claim 2, characterized in that the membrane through a thin-walled and gas-tightly closed at its ends metal tube ( 54 ) is limited. Contraption ( 36 ) according to one of the preceding claims, characterized in that at least one outer wall of the working space is also formed as a membrane. Contraption ( 36 ) according to 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. Contraption ( 36 ) according to claim 5, characterized in that the gas volume ( 58 ) a closable opening ( 60 ) with which the pressure can be adjusted. Contraption ( 36 ) according to one of the preceding claims, characterized in that the membrane ( 54 ) at least one bead ( 78 ) having. Contraption ( 36 ) according to claim 7, characterized in that the membrane ( 54 ) several beads ( 78 ) which have different heights and / or a different course and / or a different cross section. Contraption ( 36 ) according to one of the preceding claims, characterized in that the membrane ( 54a ) at least one stop section ( 80a ), which with a maximum deflection of the membrane ( 54 ) with a counter surface ( 80b ) comes into contact. Contraption ( 36 ) according to claim 9, characterized in that the counter surface ( 80b ) on the housing ( 40 ), on a separate stop part ( 112 ), and / or on another membrane ( 54b ) is trained. Contraption ( 36 ) according to one of the preceding claims, characterized in that the enclosed gas volume ( 58 ) through a filling area ( 112 ) is reduced. Contraption ( 36 ) according to one of the preceding claims, characterized in that the gas volume ( 58 ) through at least two membranes ( 54a . 54b ) is limited, which are clamped in the area of their edges ( 82, 84 ). Contraption ( 3c ) according to claim 12, characterized in that the membranes ( 54a . 54b ) are essentially parallel overall. Contraption ( 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 ) at least one stop surface ( 80a ) or a counter surface ( 80b ), which are at a maximum deflection of the two membranes ( 54a . 54b ) touch. Contraption ( 36 ) according to one of claims 12 to 14, characterized in that the edges of the two membranes ( 54a . 54b ) tightly connected to each other and radially inwards from the sealing line ( 57 ) are clamped ( 82, 84 ). Contraption ( 36 ) according to claim 15, characterized in that the clamping ( 82 . 84 ) about a constructive elasticity ( 118 . 120 ) has. Contraption ( 36 ) according to one of claims 12 to 16, characterized in that the two membranes ( 54a . 54b ) are identical. Contraption ( 36 ) according to one of claims 12 to 17, characterized in that the working space ( 66 ) through the two membranes ( 54a . 54b ) in two areas ( 64 . 68 ) which is divided by a fluid connection ( 70 ) communicate with each other. Contraption ( 36 ) according to one of claims 12 to 18, characterized in that between the two membranes ( 54a . 54b ) an annular spacer ( 46 ) is available. Contraption ( 36 ) according to claims 17 and 19, characterized in that the fluid connection ( 70 ) is formed in the spacer. Contraption ( 36 ) according to one of the preceding claims, characterized in that it is in a housing ( 92 ) a fuel pump ( 18 ) is integrated. Contraption ( 36 ) according to one of the preceding claims, characterized in that the working space is an annular space ( 66 ) and the gas volume ( 58 ) is ring-shaped. Contraption ( 36 ) according to claims 20 and 21, characterized in that the working space ( 66 ) and the gas volume ( 58 ) in or on a cylinder ( 92 ) a fuel pump ( 18 ) at least approximately coaxial to the cylinder axis ( 90 ) are arranged. Contraption ( 36 ) according to one of claims 21 or 22, characterized in that the gas volume ( 58 ) in the manner of a spiral within the annulus ( 66 ) is arranged, the spiral ( 58 ) and the annulus ( 66 ) are at least approximately coaxial. Contraption ( 36 ) according to claim 23, characterized in that the spiral gas volume ( 58 ) against the outer wall of the work area ( 66 ) is biased. Contraption ( 36 ) according to one of claims 23 or 24, characterized in that the spiral gas volume ( 58 ) helical in the axial direction of the work area ( 66 ) runs. 2i. Contraption ( 36 ) according to claim 25, characterized in that the spiral and helical gas volume ( 58 ) in the axial direction against the ends of the work area ( 66 ) is biased. Contraption ( 36 ) according to one of the preceding claims, characterized in that the gas volume ( 58 ) is filled with helium. Contraption ( 36 ) according to one of the preceding claims, characterized in that the membrane ( 54 ) and / or the housing is magnetic at least in some areas. Contraption ( 36 ) according to one of the preceding claims, characterized in that the membrane ( 36 ) is at least partially made of a strip material that has residual stresses. Contraption ( 36 ) according to one of the preceding claims, characterized in that the membrane ( 54 ) at least one bead section ( 76 ) and at least one bellows section ( 110 ) includes. Contraption ( 36 ) according to one of the preceding claims, characterized in that the membrane ( 54 ) a fastening section on its radially outer edge ( 122 ), which is approximately parallel to the central axis ( 41 ) extends and on the housing ( 40 ) is attached. Contraption ( 36 ) according to claim 32, characterized in that it comprises a tensioning device ( 124 ) which comprises the fastening section ( 122 ) radially against the housing ( 40 ) acted upon.