ES2391727T3 - Device for damping pressure pulses in a fluid system, especially in a fuel system of an internal combustion engine - Google Patents

Abstract

Device (36) for damping pressure pulses in a fluid system (16), especially in a fuel system of an internal combustion engine, with a housing (38, 40) and with at least one working chamber (66) , which communicates at least by regions with the fluid system (16), where within the working chamber (66) there is at least one volume of gas (58) sealed tightly by at least one membrane (54), characterized in that the volume of gas (58) is limited by at least two membranes (54a, 54b), which are tightly bonded together and are radially embedded inwards, from a sealing line (57) in the region of its edges, by means of two clamping rings (82, 84).

Description

Device for damping pressure pulses in a fluid system, especially in a fuel system of an internal combustion engine

State of the art

The invention relates to a device for damping pressure pulses in a fluid system, especially in a fuel system of an internal combustion engine, with a housing and with at least one working chamber, which communicates at least by regions with the fluid system.

A device of this type is known from DE 195 39 885 A1. There is shown a fuel system of an internal combustion engine with direct fuel injection. The fuel is transported from a pre-transport pump to a high-pressure piston pump, which compresses the fuel to a very high pressure. From the high pressure plunger pump the fuel reaches a fuel collection line ("rail"). The high pressure plunger pump is driven by a camshaft of the internal combustion engine. In order to adjust the flow rate of the high-pressure piston pump, regardless of the number of revolutions of the camshaft, a quantity control valve is provided. By means of this, the transport chamber of the high-pressure piston pump can be attached during a transport time, for a short time, to the region of the fuel system placed between the electric transport pump and the high-piston pump Pressure.

By this, however, considerable pressure pulses are introduced into this region of the fuel system. To dampen these, a pressure damper is provided there. This consists of a housing and a plunger, which is prestressed by a spring.

A pressure damper is also known on the market, which works with a rubber membrane prestressed by a spring. So that in the case of systems without pressure (that is, for example in the case of the internal combustion engine disconnected), the rubber membrane does not become inadmissible over time, there is a stop on which the membrane in the case of reduced pressure.

In the known fuel system of DE 195 39 885 A1, the pressure between the pre-transport pump and the high-pressure plunger pump is almost constant. In modern fuel systems, however, this pressure can be variable. It is usually between 0.5 and 8 bars, where an overload safety must be available up to approximately 10 to 12 bars. If the known pressure damper, which has a rubber membrane, is used in such a fuel system, there is a risk that, in the case of a reduced system pressure of for example 0.5 bar and of the pressure impulses superimposed, the rubber membrane trips over the stop. Because of this, the damping action of the damper is weakened and damage to the rubber membrane can occur. The known pressure damper of DE 195 39 885 A1 with a plunger and a spring would have to be constructively very large, in turn, in the case of being used in such a fuel system with variable prepressure.

With reference to the prior art, reference is also made to documents NL-1016384, EP 1 342 911 A2, US 5,794,594, US 3,366,144, US 2002/139351 A1 and WO 01/65106 A1.

The present invention therefore has the task of perfecting a device of the class mentioned at the beginning, so that it can be used in a fuel system with variable pre-pressure, but which is constructively small and has a long service life.

This task is solved by means of a device with the particularities of claim 1.

Advantages of the invention

By using a closed gas volume, the compressibility of the gases can be used to ensure the elastic movement of the membrane necessary to dampen pressure pulses. This does not drive the membrane through any type of mechanical element, which clearly increases its useful life and reduces the risk of damage. Apart from this, a volume of gas of this type can materialize in almost any geometric shape. Therefore you can stay in the fluid system with a lot of space savings. Another advantage of the device according to the invention is that a leakage duct can be dispensed with, which again simplifies the structure of the fuel system.

A pressure damper, in which the volume of gas is limited by at least two membranes that are embedded in the region of its edges by means of clamping rings, is constructed relatively flat. This is fulfilled even more if the membranes are fundamentally parallel. With it is naturally

Logically imaginable that the volume of gas is introduced into the chamber between the two membranes while they are assembled together, so that a filling opening can be dispensed with.

Advantageous improvements of the invention are indicated in the dependent claims.

In a first improvement it is proposed that the membrane be made of metal. Such a membrane has different advantages: on the one hand, a membrane of this type is very tight to the usual gases and also to the fluids. The high density of metal membranes in relation to HC emissions plays a positive role here. On the other hand, in the case of a metal membrane, over-dilation does not occur over time even at low pressures, for example in the case of a disconnected internal combustion engine, such that a device can be used damping with a metal membrane in a fluid system, which has variable fluid pressure in a large region.

It is also advantageous that the volume of gas is formed by a thin-walled metal tube and closed at its ends in a gas-tight manner. This can materialize very easily and economically.

If at least one outer wall of the working chamber is also configured as a membrane, an additional hydraulically active surface is obtained with a minimum construction space. The effectiveness of the device according to the invention is clearly increased again by means of this, at the same time as a reduced need for space.

It is especially advantageous if the volume of confined gas available, at a normalized external pressure (for example 1013 hPa), has a defined pressure, preferably an overpressure. With a defined pressure like this, the "spring stiffness" can be adjusted. Normally an overpressure in the volume of confined gas is chosen in comparison to the external pressure, since by this means the entire possible range of tension (traction and pressure) of the membrane material can be used.

However, a depression or a normalized pressure is also imaginable. Preferably, an internal overpressure is chosen such that it corresponds approximately to half of the maximum operating overpressure, subtracting the increase in pressure that occurs due to the compression of the construction piece.

This can also optimize the effectiveness of the gas volume, due to the minimization of the volume of confined gas. By means of a minimization of this type, a greater spring rigidity materializes precisely. By this the membrane can be thinner and tensions in the membrane material can be minimized. Apart from this, a job is made possible throughout the work region without the device tripping. In addition to this, the load on the entire working region is reduced, since the internal pressure difference reduces the pressure difference on the membrane wall. In this way the membrane geometry can be designed for longer travel paths and a lower pressure load, respectively a small installation volume.

With this, the volume of gas can have a sealed opening, through which the pressure can be adjusted. This facilitates the production of gas volume. Otherwise the production itself would have to be carried out at a certain pressure.

Especially advantageous is that configuration of the device according to the invention, in which the membrane has at least one rib. By means of a rib of this type, the elastic characteristics of the membrane itself and also its resistance characteristics can be predominantly influenced. With a rib the membrane can therefore be optimally adapted to the individual requirements of the fluid system. Above all the shock absorber can have even more damping volume, with a comparable construction volume, or alternatively be constructed smaller. With this, the ribs can have a different height and / or a different path and / or a different cross section. In this way an asymmetrical spring stiffness of the membrane can be achieved, depending on the direction of the load.

By means of this, a specific constant, for example largely constant, and a rather soft elastic membrane constant can be achieved, for example, in the main working region of the pressure damping device. On the contrary, in work regions that are rarely used, greater rigidity can materialize. In this way a non-linear elastic characteristic curve can be achieved, respectively linear only by sections. Finally, by means of this, an optimum damping action is achieved in the entire working region of the fluid system, at the same time as a reduced construction space.

The ribs can thus be molded in such a way that the maximum tension does not occur on the edge of the membrane, and the mechanical tensions on the surface of the membrane are distributed as evenly as possible. Likewise, by means of a corresponding membrane design, the entire bandwidth of the material can be used in the tension and tension tension range.

It can also be provided that the membrane has at least one stop region, which in the case of a maximum deflection of the membrane makes contact with a counter surface. The maximum deflection is chosen with it in such a way that precisely damage to the membrane is still avoided, for example a plastic deformation. This device is therefore at least in a certain region "protected against overloads", that is, it shows even in the case of overloads still a damping function, without being damaged.

In an improvement for this it is proposed that the counter surface be configured on the housing, on a separate stop piece, and / or on another membrane. The overload protection can therefore be realized in different ways, very simple and economical. The stop surface on the housing can be produced, for example, by deep drawing, which is very simple and economical. A separate stop piece is also economical, where for the same damper stop pieces can be provided, so that the same device can easily adapt to different conditions of use. The stop surface on another membrane saves space in turn.

In another refinement it is also proposed that the volume of confined gas be reduced by a filling region. This filling region may also be formed by the stop piece (this then acts as a "fill piece") or a housing segment. As already mentioned above, by reducing the volume of gas, the spring stiffness of the device can be increased. As a consequence the membrane can be thinner, which results in good dynamics and a small constructive size.

A device of this type is also proposed, in which the volume of gas is formed between the two membranes and the two membranes in each case have at least one abutment surface, respectively a counter surface, which make mutual contact in the case of a maximum deviation of both membranes. By means of this, the fact that, in the case of a high pressure, the two membrane surfaces move relative to each other is used. If they come into mutual contact, they rest with the stop surfaces on each other. These abutment surfaces can be executed in plane, to obtain a clean seat of the membranes on each other. An overload of the membranes in the case of excessive pressure is effectively discarded by this, without requiring a separate stop.

It is also possible that the edges of both membranes are tightly bonded together, and that they are embedded radially inwards from the sealing line. Especially when the joint is made by welding seam, this configuration of the device according to the invention prevents welding seams from having to withstand additional mechanical forces. The seal is used for sealing only in this way and you do not have to take on other tasks and, in this way, you can safely meet particularly high sealing requirements. For the assessment of the fatigue durability of the pressure absorber according to the invention, therefore, it is only necessary to take into account the membranes themselves.

With this, it is especially advantageous if the embedding has a constructive elasticity. It is understood as an elasticity such that it is "constructively desired". For example, a clamping ring of a rubber elastic material can be used, or a metal clamp having an elastic segment can be used. In this way, secure fixation of the membranes is achieved on the one hand and, on the other hand, manufacturing tolerances can be compensated. Basically the embedment can be applied to any point of the membrane, although a supplement in the region of a central plane of both membranes is especially favorable.

The costs for the device according to the invention are reduced if the two membranes are identical.

The construction space of the device according to the invention is especially small, if the working chamber of the two membranes is divided into two fluid regions, which communicate with each other by means of a fluid joint.

An annular separator between the two membranes defines, respectively, the volume of confined gas in a simple way. In this case it is economically possible to configure the fluid junction, which joins the two fluid regions of the working chamber together, in the separator.

It is especially advantageous if the device is integrated in a housing of a fuel pump. There, the advantages according to the invention are particularly noticeable, since such a fuel pump can usually be built very small.

In the fuel pumps, peripheral regions are often available, in which trees or plungers are arranged. In these cases, the damping device according to the invention can be accommodated in a way that saves space in particular, if the working chamber comprises an annular chamber and the volume of gas is also annular. This is especially advantageous if the working chamber and the volume of gas are arranged,

on a cylinder of a fuel pump, at least almost coaxially to the cylinder axis. The pressure damper thus surrounds the cylinder and the piston available therein, which further produces another noise attenuation.

It is also proposed that the volume of gas be arranged as a spiral in the annular chamber, wherein the spiral and the annular chamber are at least approximately coaxial. By means of such a spiral, a large deformation surface is obtained, which contributes to an especially effective impulse damping.

When the spiral-shaped gas volume is prestressed against the outer wall of the working chamber, a fixation of the volume of gas in the working chamber is obtained without additional parts.

The effective surface of the gas volume can be raised again if the spiral gas volume runs helically in the axial direction of the working chamber.

This in turn makes it possible to fix the gas volume without additional parts, if the spiral and helical gas volume is prestressed axially against the front ends of the working chamber.

Another preferred configuration of the device according to the invention stands out because the volume of gas has been filled with helium. This facilitates the detection of a leak.

Apart from this, the membrane and / or the housing can be magnetic. By means of a corresponding production process (for example, mechanical rolling and coining), a martensitic structure ("drawing martensite") is produced in the material, which has magnetic characteristics. If this magnetic characteristic is specifically maintained in the corresponding construction part, the device can capture dirt particles existing in the fluid and prevent further propagation. This increases the reliability of the components available in the fluid system, for example a pump. Apart from this, costs are saved, since the complex demagnetization of the construction piece is not appropriate. Because there are no parts in the device that make contact with each other and move relative to each other, the dirt particles captured do not cause any functional damage to the device.

It is also possible that the membrane is produced with a broadband material, which has its own tensions. The tensions of this type lead, during the forming process, to a flat contraction, so that the material warps in the forming state. This can then be used to simplify the production of the membrane dose, especially when it has at least one bellows segment. Because of the contraction, a specific separation of the membrane regions, located in flat juxtaposition in the state without pressure, is no longer necessary. The safe evacuation of the membrane and the filling of the gas volume are therefore possible in a simple and reliable way, for example with helium.

The assembly sequence can thus be as follows: first, the individual segments ("segments") of the membrane are placed on top of each other, and "stacked" in a welding device. After closing the welding device, its interior space is evacuated and filled with filling gas, for example with helium, at a desired pressure. In this phase, by means of the contracted membrane segments, it is guaranteed that the filling gas flows safely to all the cavities. Then the isolated segments are compressed and welded together.

In another advantageous configuration of the device according to the invention, the membrane comprises at least one rib segment and at least one bellows segment. This allows the combination of the advantages of both executions.

Apart from this, it is preferred that the membrane has a fixing segment on its outer edge, which extends almost parallel to the central axis and is fixed to the housing. In this way, the entire inside diameter of the housing can be used hydraulically, minimizing the necessary construction space and reducing costs.

With this it is possible that the device comprises a tensioning installation, which drives the fixing segment radially against the housing. The tensioning system can be configured, for example, as a tensioning ring. Through it, the membrane fixing to the housing is discharged.

He drew

Especially preferred exemplary embodiments of the present invention are explained in detail below, with reference to the attached drawing. In the drawing they show:

1 shows a schematic representation of a fuel system of an internal combustion engine, with a fuel pump and a device available there to dampen pressure pulses;

2 shows a section through a first exemplary embodiment of the device for damping pressure pulses of FIG. 1;

Figure 3 a detail III of the device for damping pressure pulses of Figure 2;

Figure 4 a section through a second embodiment of the device for damping pressure pulses of Figure 1;

Figure 5 shows a detail V of the device for damping pressure pulses of Figure 4;

6 shows a schematic section through a membrane of the pressure damping device of FIG. 4;

Fig. 7 a section through a fuel pump with a third exemplary embodiment of a device for damping pressure pulses;

Figure 8 shows a section through a region of the fuel pump of Figure 7, with a device for damping pressure pulses;

Figure 9 a section through a device for damping pressure pulses;

Figure 10 a section through a device for damping pressure pulses;

Figure 11 a section through a device for damping pressure pulses;

Figure 12 a section through a device for damping pressure pulses;

Figure 13 a section through a device for damping pressure pulses; Y

Figure 14 a partial section through a device to dampen pressure pulses.

Description of the execution examples

In Figure 1 a fuel system of an internal combustion engine carries together the reference symbol 10. The internal combustion engine itself has not been shown in detail.

The fuel system 10 comprises a fuel container 12, from which an electric fuel pump 14 transports the fuel into a low pressure fuel line 16. The low pressure fuel line 16 leads to a high piston pump pressure 18, which has been symbolically represented by strokes and dots.

The high pressure plunger pump 18 comprises a transport chamber 20, which is limited by a plunger not shown in Figure 1. The plunger is reciprocated by a drive shaft not shown. The drive shaft is in turn driven by the camshaft, in turn not shown, of the internal combustion engine. The high pressure plunger pump 18 further comprises an intake valve 22, which is configured as a check valve. Apart from this there is an exhaust valve 24, which is also formed by a check valve.

The high pressure plunger pump 18 compresses the fuel at a very high pressure and transports in a fuel collection line 26 ("rail"). In it the fuel is stored at high pressure. Various fuel injection devices 28 are connected to the fuel collection line 26. These inject the fuel directly into combustion chambers 30 associated in each case with them.

In order to adjust the flow rate of the high pressure piston pump 18 regardless of the number of revolutions of the drive shaft, a quantity control valve 32 is provided. This is actuated by a magnetic actuator 33, which in turn is activated. by a control apparatus not shown. The quantity control valve 32 is configured such that, during a transport stroke of the high pressure plunger pump 18, the inlet valve 22 can be forcedly opened. By means of this the fuel placed under pressure in the transport chamber 20 is not transported in the fuel collection line 26, but of

turn in the low pressure fuel line 16. The corresponding switching position of the quantity control valve 32 bears the reference symbol 34.

The pressure pulses introduced by this into the low pressure fuel line 16 are absorbed by a device for damping pressure pulses. This has the reference symbol 36 in the figure and is hereinafter referred to briefly as "pressure absorber". The pressure damper 36 is structured 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 is shaped like a mushroom in the section shown in Figure 2, and is therefore symmetrical in rotation to a central axis 41. It comprises an installation segment 42 with an inlet channel 43 practiced centrally and a base segment 44, for this in total in the form of a saucer and circular in a plan view, whose plane forms a total almost right angle with respect to the axis center 41. The upper part 40 of the housing is also shaped like a saucer and is circularly configured in a plan view.

An annular spacer 46 is disposed between the base segment 44 of the lower part 38 of the housing and the upper part 40 of the housing. This is fixedly welded through welding seams 48a and 48b, on the one hand, to the base segment 44 of the lower part 38 of the housing and, on the other hand, to the upper part 40 of the housing. To an annular clamping segment 52, which extends over the separator 46 radially inward, two circular membranes 54a and 54b are fixed together in a plan view. The fixing is done by welding seams 57a and 57b peripheral on the outermost edge of the membranes 54a and 54b (see Figure 3). The two membranes 54a and 54b have thin walls and are made of metal, preferably stainless steel.

A gas volume 58 is confined between the upper membrane 54a and the lower membrane 54b and the separator 46. The gas is introduced through a channel 60, which is available in the annular segment 46 (see Figure 2). After the introduction of the gas in volume 58, between both membranes 54a and 54b, the channel 60 is closed by a sphere 62. The entire region between the base segment 44, the upper part 40 of the housing and the separator 46 forms a working chamber 66. The volume of gas 58 is therefore disposed within the working chamber 66.

Between the base segment 44 of the lower part 38 of the housing and the lower membrane 54b a first fluid region of the working chamber 66 is formed. Between the upper part 40 of the housing and the upper membrane 54a a second is formed fluid region 68 of the working chamber 66. Both fluid regions 64 and 68 can communicate with each other via a channel 70 in the annular separator 46.

The two membranes 54a and 54b have an identical structure (for a better understanding in FIG. 3 only all reference symbols have been included for the upper membrane 54a): on their radial outer edge they have a radially extending clamping segment 72, with which they are welded to the ring separator 54b. From the clamping segment 72 of the membrane, an elastic segment 74 is bent at an angle of approximately 80 °. The elastic segment 74 therefore runs in an approximately axial direction. On the elastic segment 74, a rib segment 76 which runs radially is formed. This one stands out for several ribs 78 that run. The ribs 78 run concentrically around the central axis 41 of the pressure absorber 36. A central region of the two membranes 54a and 54b is executed flat. The corresponding region in the membrane 54a is designated as the stop segment 80a, the corresponding region on the membrane 54b as a counter surface 80b (see Figure 2).

The pressure damper 36 works as follows:

Through the inflow channel 43 in the installation segment 42, the lower fluid region 64 is communicated in Figures 2 and 3 (the terms "below" and "above" from now on always refer to the figures; the damper The pressure can be arranged essentially at any point in the chamber) of the working chamber 66 with the low pressure fuel line 16.

The upper fluid region 68 of the working chamber 66, in turn, communicates with the lower fluid region 64. Within the working chamber 66, the volume of gas 58 is available, limited by the two membranes 54a and 54b and by the annular separator 46. This is subjected to a slight overpressure in relation to the outside atmosphere, in the rest state of the fuel system 10. By means of this overpressure, the rib segment 76 and the segment are pre-pumped outwards. of stop 80a, respectively the counter surface 80b of both membranes 54a and 54b.

The distance between both membranes 54a and 54b and the segments 54a or 40 of the housing, adjacent thereto, is however so great that even in the idle state, that is, with the fuel system without pressure, a contact is discarded. of the two membranes 54a and 54b with corresponding segments 40 and 44 of the

Case. Such a limitation of the "stroke" of the membranes is possible through the use of metal as a membrane material.

The distance between the membranes 54a and 54b and the housing 40 or 44 has been chosen such that, with a system pressure for example less than 100 kPa in the case of a hyper-oscillation of pressure, the membranes 54a and 54b do not they make contact with the housing 40 or 44. In this way the damping function of the pressure damper 36 is guaranteed even in this operating range, respectively, of pressure.

When the fuel system 10 is in operation, that is to say the electric fuel pump 14 transports with a certain pressure, the two membranes 54a and 54b move towards each other. The pressure in the gas volume 58, on the one hand, and the stiffness of both membranes 54a and 54b have been chosen such that, at a normal operating pressure in the low pressure fuel line 16, that is approximately between 0.5 and 8 bars, there is no mutual contact of the two membranes 54a and 54b. In this way the pressure oscillations can be absorbed without problems and dampened by this in this normal operating range of the fuel system 10, by a corresponding movement of the two membranes 54a and 54b and a compression of the gas volume 58.

In the case of an overload in the low pressure fuel line 16, when the pressure rises, for example, to more than 10 bars, the stop segment 80a of the membrane 54a and the counter surface 80b on the membrane 54b make mutual contact. In this way the two membranes 54a and 54b can no longer move, so that an overload of the two membranes 54a and 54b can be ruled out. So that a clean seat of the two membranes 54a and 54b is guaranteed in the event of an overload in the low pressure fuel line 16, the stop segment 80a and the counter surface 80b are machined flat or pumped.

Apart from the pressure of the gas volume 58, which is confined between the two membranes 54a and 54b, the characteristic of the pressure absorber 36 can also be influenced by the height of the annular separator 46. This height has a special influence on the pressure to which both membranes 54a and 54b make mutual contact.

Likewise, the internal volume can be specifically reduced, by means of a suitable configuration of the internal geometry of the clamping segment 52 (for example at position 53 in Figure 3). By this, the efficiency of the pneumatic spring formed by the volume of confined gas 58 can be further increased.

Also the shape of the ribs 78 as well as their number play an essential role for the characteristics of the pressure absorber 36. In the case of a membrane with a diameter of 30-60 mm and a wall thickness of 0.2-1, 0 mm has proved to be advantageous a number of three to six ribs with different rib height. The height of the rib may vary between +/- 0.15 and 2 mm. The rib may be circular, sinusoidal or grooved.

In this way, an asymmetric spring rigidity can also be achieved in the case of a load on the two membranes 54a and 54b in Figures 2 and 3, from below or from above. By means of this it is possible to achieve a relatively reduced stiffness with constant elastic constant, in the usual operating pressure range of the fuel system, respectively of the low pressure fuel line 16, while in the case of rarely used operating ranges , for example, in the case of a very low pressure in the low pressure fuel line 16 or in the case of a very high pressure therein, a greater rigidity of the membranes 54a and 54b materializes.

By means of the shape of the ribs 78 and by the configuration of the elastic segment 74 it is achieved that the maximum tensions do not occur on the outermost edge of both membranes 54a and 54b, but are largely distributed uniformly by the diameter of the two membranes 54a and 54b. Reference is now made to Figures 4 and 5 as well as to 6. In these, a second example of the execution of a pressure damper 36 is shown. Thus, those elements and regions, which have functions equivalent to elements and regions of the Execution example shown in Figures 2 and 3, bear the same reference symbols. They are not explained again in detail.

A fundamental difference between the two exemplary embodiments is that in the case of the pressure absorber shown in Figures 4 and 5, a separator is no longer available. Instead, the upper part 40 and the base segment 44 of the housing are welded directly together. The corresponding welding seam bears the reference symbol 48. Correspondingly, the two clamping segments 72a and 72b of both membranes 54a and 54b are directly welded together (welding seam 57).

Apart from this, the two seams 54a and 54b are secured to each other in a somewhat radially inward position from the weld seam 57, with which the two membranes 54a and 54b are welded together by means of an upper clamping ring 82 and a lower clamping ring 84 that are formed on the part

upper 40, respectively the base segment 44, of the housing. By means of this, the welding seam is unloaded from mechanical loads, which joins the two membranes 54a and 54b together.

By means of a fluid joint 70 shown in the figure only in strokes, which is formed by through holes through regions in the clamping rings 82 and 84, the two fluid regions 64 and 68 are joined tightly to the fluids. of the working chamber 66. The through holes 70 must therefore be chosen in such a way that the two membranes 54a and 54b are loaded approximately equally.

Figure 6 shows the bottom membrane 54b detailed schematically. With A, the membrane depth 54b is designated, which corresponds to the maximum possible stroke. B designates a transition region, and C the height of the membrane countersink 54b.

A partial cut through a fuel pump is shown in Figure 7, such as that used as a high pressure plunger pump 18 for example in the fuel system 10 shown in Figure 1. A carcass can be recognized. cylinder 92 with a plunger 88, which limits the transport chamber 20. The quantity control valve 32 can be recognized in the upper region of the fuel pump 18. The exhaust valve 24 is located in the left region. The intake valve 22 is configured as a saucer valve under the pressure of a spring, which can be forcedly pressed to an open position by means of a pusher (without reference symbol) of the quantity control valve 32, during a transport stroke of the plunger 88.

Coaxially to a central axis of cylinder 90, a peripheral step 94 is incorporated in the outer limiting surface of the cylinder housing 92. A housing sleeve 96 is connected thereto. A peripheral step 94 and the housing sleeve 96 create a annular chamber 66 peripheral around the central axis of cylinder 90. This communicates on the one hand, through a channel 100, with a low pressure inlet 102 of the fuel pump 18. On the other hand, it communicates through a channel 104 with a pressure discharge slot 106, which is available in a cylindrical bore 108, in which the plunger 88 is guided.

In the annular chamber 66, two annular peripheral membranes 54a and 54b are arranged. Its outer edges are welded through welding seams 57a to 57d, on the one hand to the cylinder housing 92 and, on the other hand, to the housing sleeve 96. By means of this two volumes of gas 58a and 58b are created separately each. Among these there is a fluid region 64 of the working chamber 66, which communicates especially through the channel 100 with the low pressure inlet 102. The annular chamber 66 and the gas volumes 58a and 58b form thus a pressure damper 36, which is coaxially arranged to the central cylinder axis 90 of the high pressure plunger pump 18.

In FIG. 8, another annular pressure damper 36 is shown. Thus, these elements and regions, which have functions equivalent to elements and regions of the pressure damper 36 represented in FIG. 7, bear the same reference symbols. They are not explained again in detail.

The pressure damper 36, which is shown in Figure 8, comprises a flattened metal tube 54 that is sealed by gas-tight welding at the ends. Its interior forms a volume of gas

58. The metal tube 54a is wound in the working chamber 66, spirally and helically, coaxially to the central cylinder axis 90. By means of this it is subjected to a pre-tension, on the one hand in relation to the housing sleeve 96 and, on the other hand, in relation to the upper and lower front surfaces of the working chamber 66 in Figure 8, and is fixed by this.

In Figure 9 another pressure damper 36 is shown again. This is applied here in all the following figures, that these elements and regions, which present functions equivalent to elements and regions that have already been explained in relation to previous figures, They carry the same reference symbols. Normally they are not explained again in detail.

The pressure damper 36 shown is thereby configured in the left half of Figure 9 differently than in the right half. Both devices 36 have in common that they only have a single membrane

54. This is welded 57 to the upper part 40 of the housing in the region of its clamping segment 72. Unlike the membrane for example of Figures 2 and 3, the membrane 54 shown in Figure 9 has a segment of bellows 110, which is arranged between the rib segment 76 and the clamping segment 72 and is structured with insulated segments 110a to 110d. This bellows segment 110 makes possible a relatively large volume variation of the gas volume 58, confined by the membrane 54 and the housing 40.

The volume of gas 58 is thereby reduced in total by means of which a filling body 112 is attached between the membrane 54 and the upper part 40 of the housing to the upper part 40 of the housing. A stop segment 80a extends in the left half of Figure 9, from the rib segment 76 of the membrane 54 towards the lower part 38 of the housing, while in the right half of Figure 9 the segment of stop 80a towards

filling body 112. Depending on each case, the filling body 112 or the lower part 38 of the housing acts as a counter surface 80b for the stop segment 80a.

The volume of gas 58 confined by membrane 54 has been filled with helium. This is subjected to an overpressure, which corresponds approximately to half of the overpressure that occurs in operation, subtracting that increase in pressure that is caused by the compression of the membrane 54. This is used for the membrane 54 a metallic material magnetic. By means of this, the pressure absorber 36 acts in a manner similar to a "dust trap", since by means of it magnetic particles of dirt are captured from the fluid and its propagation in the fluid system 10 is prevented.

Apart from this, a bandwidth material 110 is used in particular for the bellows segment 110 of the membrane 54, in which tensions are produced that lead to a flat contraction of the insulated segments 110a, 110b, 110c and 110d. This leads to the fact that during the production of the bellows segment 110 the insulated segments 110a to 110d never make a mutual contact so tightly that an evacuation of the air and a filling with helium is not reliably possible. An imaginable way of proceeding for the production of the bellows segment 110 is as follows:

First, the insulated segments 110a to 110d of the bellows segment 110 are stacked in a welding device (not shown). Then the welding device is closed and its interior space is evacuated. The inner space of the welding device is then filled with helium, to a desired internal pressure. By segments 110a to 110d that show a contraction of the bellows segment 110, it is guaranteed that, even in the corresponding cavities, helium can flow reliably. The isolated segments 110a to 110d are then compressed and welded together at 114 (for reasons of clarity, this reference symbol has only been registered at one point on the left side of Figure 9).

An alternative to this is shown in Figure 10. The pressure absorber 36 shown in Figure 10 differs from that shown in Figure 9 in that, instead of a separate filling body 112 in the upper part 40 of the housing, there is a segment 112 produced by deep drawing, which on the one hand reduces the volume of confined gas 58 and, on the other hand, has the counter surface 80b that cooperates with the stopper segment 80a of the membrane 54.

Figure 11 shows a pressure damper, in which there is a separate filling body 112, which however is not hollow, but has a solid structure and apart from this presents, in a region 116 turned towards the segment of stop 80a of the membrane 54, a smaller diameter. In this way the contour of the filling body 112 of Figure 11 is somewhat adapted to the contour of the membrane 54, such that the corresponding volume of gas 58 is especially reduced.

An embodiment is shown in Figure 12, in which two membranes 54a and 54b are provided, corresponding for example to the embodiment of a pressure absorber 36 shown in Figure 4. Unlike in the Figure 4, in the exemplary embodiment shown in Figure 12, a bellows segment 110 is disposed for each membrane 54a and 54b, which however is executed more simply than that of Figures 9 to 11. The shock absorber pressure shown in figure 12 presents - analogously to that shown in figures 4 and 5 - upper and lower clamping rings 82 and 84, which however have only been shown schematically in figure 12. By these the hydraulically active surface is maximized of the membranes 54a and 54b, which can be used for a reduction in the total constructive size of the pressure damper 36. The clamping rings 82 and 84 are supported, however, through elastic segments os 118 and 120, in the upper part 40, respectively in the lower part 38 of the housing. In this way, manufacturing tolerances of membranes 54a and 54b can be compensated.

Between the two membranes 54a and 54b a clamping ring 122 is secured in the form of a disk, which has a central opening 124. A filling body 112 with two parts is inserted therein, and the clamping ring 122 is secured between the two halves 112a and 112b of the filling body 112. Alternatively, it is also possible that a peripheral groove is provided in the filling body 112, in which the edge of the opening 124 of the clamping ring 122 is engaged. An embodiment is also imaginable with a piece of the clamping ring 122 with the filling body 112.

In Figure 13 another variant of a pressure damper 36 is shown again. In the case of this pressure damper 36 no filling body is available, such that this device has a structure similar to that of which shown in figures 4 and 5. The differences especially affect the clamping rings 82 and 84, with which the membranes 54a and 54b are attached to the housing 40 and 38: the clamping rings 82 and 84 have elastic segments in cantilever, wherein an elastic segment 118a or 120a positions the membranes 54a and 54b in Figure 13 in the vertical direction, while an elastic segment 118b or 120b positions, respectively, centers both membranes 54a and 54b in Figure 13 in the horizontal direction.

The elastic segments 118a and 120a are formed by insulated stirrups directed radially into the two clamping rings 82 and 84, which are prestressed in the installation position shown in Figure 13 against the upper part 40, respectively the lower part 38, of the housing. The elastic segments 118 or 120 are in turn formed by insulated stirrups that act radially outwardly, which make contact with the inner shell surface of the upper part 40 of the housing 40, respectively are prestressed against it.

In Fig. 14, another pressure damper 36 is shown again. In the case of this, it is arranged on the radially outer edge of the rib segment 76 of a fixing segment 122 of the tube type, which extends approximately parallel to the axis center 41 of the pressure damper 36 and at 57 is welded with its edge to the housing 40. Finally, the membrane 54 is therefore fixed directly to the housing 40, which also saves additional necessary structures. In addition to this, the pressure damper 36 has in figure 14 a tension ring 124, which presses the fixing segment 122 radially from the inside against the housing 40. By means of this the welding seam 57 is mechanically discharged. The seam Welding 57 located more radially on the outside allows the use of the total inner diameter of the housing 40 as a hydraulically effective diameter. This reduces production costs.

The volume of gas 58 can be installed during the production of welding seams 57 (welding in a pressure chamber). Also, the working chamber 66 could be filled posteriorly through the opening 60, which is then closed by the element 62. The latter can be welded, for example, to the housing 40. As in the exemplary embodiments of Figures 9 to 11, also in the pressure damper 36 shown in Figure 14 the volume of gas 58 is configured between the membrane 54 and the housing 40. This leads to a minimization of the necessary construction space.

Also the following particularities can represent, both in isolation and in any combination, advantageous configurations of the described or claimed invention:

•

The device described or claimed, in which the membrane 54 is made of metal.

•

The device described or claimed, in which the membrane is limited by a thin-walled metal tube 54 and closed at its ends in a gas-tight manner.

•

The device described or claimed, in which at least one outer wall of the working chamber is also configured as a membrane.

•

The device described or claimed, in which the volume of confined gas 58 has, at a normalized external pressure, a defined pressure, preferably an overpressure.

•

The device described or claimed, in which the volume of gas 58 has a sealed opening 60, through which the pressure can be adjusted.

•

The device described or claimed, in which the volume of confined gas 58 is reduced by a filling region 112.

•

The device described or claimed, in which the membranes 54a, 54b are altogether fundamentally parallel.

•

The device described or claimed, in which the volume of gas 58 is formed between the two membranes 54a, 54b and the two membranes 54a, 54b have in each case at least one stop surface 80a, respectively a counter surface 80b, which make mutual contact in the case of a maximum deviation of both membranes 54a, 54b.

•

The device described or claimed, in which the recess 82, 84 has a constructive elasticity 118, 120.

•

The device described or claimed, in which the two membranes 54a, 54b are identical.

•

The device described or claimed, in which the working chamber 66 is divided by the two membranes 54a, 54b into two regions 64, 68, which communicate with each other by a fluid joint 70.

•

The device described or claimed, wherein between the two membranes 54a, 54b there is an annular spacer 46.

•

The device described or claimed, in which the fluid junction 70 is configured in the separator.

•

The device described or claimed, in which the volume of spiral gas 58 is prestressed against the outer wall of the working chamber 66.

•

The device described or claimed, in which the volume of spiral gas 58 runs helically in the axial direction of the working chamber 66.

•

The device described or claimed, wherein the spiral and helical gas volume 58 is prestressed axially against the front ends of the working chamber 66.

Claims (15)

1. Device (36) for damping pressure pulses in a fluid system (16), especially in a fuel system of an internal combustion engine, with a housing (38, 40) and with at least one working chamber (66), which communicates at least by regions with the fluid system (16), where inside the working chamber

(66)

 at least one volume of gas (58) is sealed sealed by at least one membrane (54), characterized in that the volume of gas (58) is limited by at least two membranes (54a, 54b), which are joined each other tightly and are embedded radially inwards, from a sealing line

(57)

 in the region of its edges, by means of two clamping rings (82, 84).

2.

 Device (36) according to one of the preceding claims, characterized in that the membrane (54) has at least one rib (78).

3.

 Device (36) according to claim 2, characterized in that the membrane (54) has several ribs (78), which have different height and / or a different path and / or a different cross-section.

Four.

 Device (36) according to one of the preceding claims, characterized in that the membrane (54a) has at least one stop segment (80a), which in the case of a maximum deflection of the membrane (54) makes contact with a counter surface ( 80b).

5.

 Device (36) according to claim 4, characterized in that the counter surface (80b) is configured on the housing (40), on a separate stop piece (112), and / or on another membrane (54b).

6.

 Device (36) according to one of the preceding claims, characterized in that it is integrated in a housing

(92) of a fuel pump (18).

7.

 Device (36) according to one of the preceding claims, characterized in that the working chamber comprises an annular chamber (66) and the volume of gas (58) is annular.

8.

 Device (36) according to claim 6, characterized in that the working chamber (66) and the volume of gas (58) are arranged, in or on a cylinder (92) of a fuel pump (18), at least almost coaxially to the cylinder shaft (90).

9.

 Device (36) according to claims 6 or 7, characterized in that the volume of gas (58) is arranged as a spiral within the annular chamber (66), wherein the spiral (58) and the annular chamber (66) They are at least approximately coaxial.

10.

 Device (36) according to one of the preceding claims, characterized in that the volume of gas (58) has been filled with helium.

eleven.

 Device (36) according to one of the preceding claims, characterized in that the membrane (54) and / or the housing are magnetic at least by regions.

12.

 Device (36) according to one of the preceding claims, characterized in that the membrane (36) is produced at least in part with a broadband material, which has its own tensions.

13.

 Device (36) according to one of the preceding claims, characterized in that the membrane (54) comprises at least one rib segment (76) and at least one bellows segment (110).

14.

 Device (36) according to one of the preceding claims, characterized in that the membrane (54) has on its radially outer edge a fixing segment (122), which extends almost parallel to the central axis

(41) and is fixed to the housing (40). 15. Device (36) according to claim 14, characterized in that it comprises a tensioning installation (124), which drives the fixing segment (122) radially against the housing (40).