EP1435455A1 - Damping element for a high pressure accumulator - Google Patents

Abstract

The device has a storage volume (24) for a hydraulic liquid, at least one union each for feeding and removing the liquid at high pressure and a vibration damping element (22) in the storage volume. The vibration damping element has at least one choke plate movably guided in the longitudinal direction of the storage volume under spring action that leaves part of the cross-section free for the passage of hydraulic liquid.

Description

State of the art

The invention relates to a hydraulic high-pressure accumulator a storage space for a hydraulic fluid as well at least one connection for the supply and for the Removal of the high-pressure hydraulic Liquid from the storage space, being in the storage space a vibration damping element is arranged. such Hydraulic high-pressure accumulators can be found, for example, at Fuel injection systems for internal combustion engines Use. Alternatively, such hydraulic systems also on flow test benches and other test benches, as well as used in the chemical industry.

A high-pressure pump delivers in common rail injection systems the fuel to be injected from a tank into the Central high-pressure fuel accumulator, which acts as a "common rail" referred to as. Lead from the high-pressure fuel reservoir High pressure lines to the individual injectors of the Internal combustion engine through which fuel enters the combustion chambers is injected. The individual injectors are in Dependence on the operating parameters of the Internal combustion engine controlled by a control device, so that the desired amount of fuel to the desired Time in the combustion chambers of the internal combustion engine is injected. Through the high-pressure fuel reservoir are the pressure generation and the injection from each other decoupled.

Especially with jet-guided combustion processes for gasoline direct injection or diesel direct injection are very high demands on the Stability of the spray form. This is it required to increase the fuel pressure. simultaneously very short injection times can be achieved, which allow variable injection, for example Multiple injections, as already in diesel systems are provided.

However, these high flows lead to a quick one Volume decrease in the injector, which in pressure pulsations in the High pressure rail result. This has disadvantages in the form of strong noise and mechanical Load on the rail. At the same time, the constant change of overpressure and underpressure waves at the injection nozzle cause pronounced fluctuations in the injection quantity.

To the vibrations in conventional Damping high-pressure fuel storage becomes a relative large volume of the high-pressure fuel reservoir is required. As a result, the high pressure resistant design of the High-pressure fuel storage difficult. In addition, the Space requirements as well as the manufacturing costs.

A conventional high-pressure fuel storage is for Example described in DE 196 00 480. The known High-pressure fuel accumulator consists of a elongated tubular body with several Connections for supplying injectors. The tubular Body is used to maintain pressure, to dampen Pressure surges in the high pressure area of the Fuel injection system and the distribution of the Fuel to the various injectors. Depending on Tuning the fuel injection system, especially with a small inner pipe diameter and one large pipe length, pressure fluctuations in the High-pressure fuel accumulator. These pressure vibrations can cause some injectors as a result of Forming a standing wave is not the desired one Inject the amount of fuel. In addition, in the rail and rising pressure waves cause the Alternating or stochastic injectors not the Inject the desired amount of fuel.

From DE 100 47 351 Al is a high pressure hose for Fuel injection systems known, which in its Inside has a damping element. This Damping element divides that by High pressure fuel hose flowing fuel in two Partial flows, which in the damping element trained throttling points with each other hydraulically Connect. These throttling points are only developing at higher flow rates a noteworthy Damping effect, so they are used for damping high-frequency pressure pulsations with small amplitudes are not are suitable. The vibration damping element acts it is also a tubular body that for example formed from wound plastic strips is.

Part of the electricity runs inside Vibration damping element, another part of the current outside on the same vibration damping element. The outer Side between the annulus and the vibration damping element represents a dead end for the fluid, so that this through the gaps in the vibration damping element must press and there is a pressure throttling.

Finally, it is known from DE 102 16 693, in one High-pressure fuel storage in compressible use To provide storage space, this being for example, a coating or inner lining of the storage space can act or a partial volume of the Storage space taken up by the compressible use becomes. Let through such a compressible insert however, pressure pulsations with large amplitude only filter out limited.

The invention has for its object a High-pressure hydraulic accumulator of the type mentioned at the beginning To provide its damping properties in particular can also dampen high amplitudes and Avoid individual vibrations. In addition, both Overpressure waves and vacuum waves are damped can.

This task is done with a hydraulic high pressure accumulator a storage space for a hydraulic fluid as well at least one connection for the supply and the discharge hydraulic fluid under high pressure the storage space, being in the storage space Vibration damping element is arranged, solved, in which the vibration damping element at least one Throttle disc includes that in the storage space in Longitudinal direction of the storage space guided resiliently is, the throttle disc is part of the cross section of the storage space leaves open for the passage of the hydraulic fluid.

Advantages of the invention

Due to the arrangement of throttle discs in axial Direction, i.e. in the longitudinal direction of the pressure accumulator space, pressure waves in the hydraulic path be dampened. By arising over and Vacuum waves that hit the at least one Throttle disc will hit at least one Throttle disc on the pressure drop occurring deflected, with pressure waves in the throttle plate Deflect the direction of travel and the vacuum waves Throttle disc against the direction of the pressure wave deflect. Here, the spring-loaded Throttle washers part of the pressure energy in spring energy implemented because the pressure waves work against the springs. The pressure waves settle after one Throttle disc continues with reduced energy, taking it have a reduced amplitude which, if further Chokes are provided, passed on to them.

The springs will return to their original position deferred once the maximum of the local pressure wave has passed the throttle disc, being the stored one Give energy back to the hydraulic fluid. hereby the system begins to oscillate, taking the fuel between the throttle disks in turn as dampers for the Vibrations acts. As a result, the course of the respective pressure wave flattened, pressure rise or pressure drop also occurs delayed and with less incline, that is Maximum is lower. It is achieved that Single pressure vibrations superimposed in a system Vibrations are transferred. The individual vibrations are less pronounced in terms of their amplitude, and there are no standing waves in the system.

Due to the good damping properties, this can Storage volume of the storage space can be kept low, making manufacturing costs and space requirements clear are reduced, especially because of otherwise arising costs at the to be generated High pressure resistance of the storage room. A high pressure resistant The design for pressures up to over 2000 bar is small Dimensions of the high-pressure storage space more easily possible.

Advantageous variants of the invention provide that the at least one throttle disc has a bore that is particularly centrally located, and by which Fluid and the pressure wave are then reduced in force continue, by hitting the pressure wave on the Throttle plate a deflection of the throttle plate and thus converts the pressure energy into spring energy becomes.

It can also be provided that the Throttle disks with regard to their outer contour and / or Dimensions of the inner contour and / or dimensions of the Pressure accumulator are adjusted. This will in particular achieved that safe guidance of the throttle discs is given, and moreover it can be avoided that Larger amounts of the fluid on the outside of the throttle disc squeeze past. It can also be provided that the Springs that support and stabilize the throttle plate, with regard to their external dimensions also essentially the Correspond to the internal dimensions of the storage space, so that the Springs which have a certain longitudinal extent and for example, include multiple spring windings, if they are designed as coil springs, safely in the storage space are guided and so a tilting or kinking of the spring and thus a hindrance to the compressibility of the springs can be avoided. By guiding the springs ensures that the pressure energy to be converted by the springs can be picked up and released again, over a variety of cycles.

Alternatively, it can also be provided that the Throttle disks with some distance to the inner wall of the Storage space are performed, then be provided can, the throttle discs without bore or with additional hole in the middle or on another Training position.

It can be particularly advantageously provided that several Vibration damping devices consisting of springs and Throttle disks, arranged one behind the other, the various vibration damping devices can have different damping parameters. The Damping parameters can on the one hand via the mass and the Spring constant of the vibrating mass system as well as the other can be set via the flow. The parameters: Spring stiffness, housing diameter of the storage space and the throttle coefficient, which is the ratio of the Throttle disc diameter to the bore diameter or as a ratio of the disc diameter to Internal dimension of the storage space results, i.e. the ratio free cross-section / hidden cross-section at the Drossse slice, can be varied as desired and thus adapt different hydraulic fluids.

In addition, multiple holes can be provided provide, with an enlargement of the Bore cross section of the throttle discs Throttle coefficient is reduced and a reduction in the Deflection amplitude of the throttle discs is achieved. Furthermore, by increasing the spring force Reduction of the deflection of the throttle disks achieved become. In this way it can be done Vibration damping element on the type of expected Set vibrations with regard to frequency and amplitude.

It can in particular be provided that the Throttle disks are arranged between two springs the throttle discs are preloaded in a basic position keep at constant pressure in the storage space, and that ever according to the direction of the pressure difference Deflection of the throttle disc in the longitudinal direction or axial direction of the elongated Storage space. This way it can be special simply both a balance of overpressure and of Vacuum waves can be achieved, both types of pressure can be equalized equally well.

It can be provided that the Hydraulic high-pressure accumulator a high-pressure fuel accumulator for fuel injection systems for internal combustion engines, the storage space in particular as a common rail can be trained. The storage space can alternatively but also be a separate storage space, for example is connected downstream of a common rail.

Alternatively, it is also possible that the High pressure hydraulic accumulator Part of a hydraulic system is a test bench, in particular Flow test stands for fuel injectors thereof benefit, since these often have problems with pressure surges occur. In addition, use in the chemical industry conceivable as advantageous.

Further advantages and advantageous configurations of the Invention are in the drawing below, the Description and claims listed.

drawing

Figur 1:

eine schematische Darstellung des Einbaus des Dämpfers in einen Kraftstoffpfad eines Kraftfahrzeuges;

Figur 2:

eine schematische Darstellung der Schwingungsdämpfungseinrichtung zum Schutz eines Messgeräts in einem Durchflussprüfstand; und

Figur 3:

eine schematische Darstellung der Schwingungsdämpfungseinrichtung in einem Ruhezustand.

The drawing shows:

Figure 1:

a schematic representation of the installation of the damper in a fuel path of a motor vehicle;

Figure 2:

a schematic representation of the vibration damping device for protecting a measuring device in a flow test bench; and

Figure 3:

is a schematic representation of the vibration damping device in a rest state.

Description of the embodiments

Figure 1 shows a first embodiment of a Hydraulic high pressure storage system 4, namely one High-pressure fuel storage system in longitudinal section. The High-pressure fuel accumulator has a common rail 10 into the high-pressure fuel via a Inflow 12 arrives. The common rail has an im Essentially cylindrical geometry. The fuel is in the inlet 12 by means of a not shown High pressure fuel pump promoted.

The end 14 of the fuel inlet 12 opposite Common rails are hydraulically sealed, for example closed by a plug. At a Outer surface 16 of the common rail 10 are different Connection piece 18 arranged. Via the connecting piece 18, the fuel in the common rail 10 becomes the Injectors 20 transported. In another Connection piece 21 is screwed in a pressure sensor (not shown).

In the direction of flow between connecting piece 18 and Injectors 20 is a damping device 22 each Injector provided in a storage space 24 is arranged with a cylindrical interior and Outer contour.

The damping devices 22 serve the Pressure fluctuations caused by the high flow rates the injectors 20 due to multiple injections are achieved, especially negative pressures that starting from the injectors into the common rail 10 fight back, dampen.

Figure 2 now alternatively shows a structure for a Hydraulic system of a test bench, for one Flow test of an injector, which is also included here 20 is designated.

The hydraulic fluid passes through a feed (also referred to here as 12) in a measuring device such. B. a mass flow meter 26, and from there on a connecting piece 28 in a damping device or in a vibration damping element 22, the is connected between the measuring device and the injector Pressure surges in a test system for beam-guided Injection processes occur towards the meter too dampen.

A similar structure is also used for operations conceivable in the chemical industry.

FIG. 3 shows a damping element as it is shown in FIG. 1 and 2 and designated by reference numeral 22 is on average, at rest. The damper itself is while in a storage space 24, which is by a cylindrical Housing is formed, housed. On both sides of the Head ends of the cylindrical housing has Storage room 24 hydraulic connections 30. The Flow direction is indicated by arrows that means that shown in the drawing on the right hydraulic connection leads to the injector 20.

The damper 22 has two throttle disks 32, which has three springs 34 ', 34 "and 34"' in the housing of the Storage space are stored and in terms of their axial Position in this are stabilized in a rest position.

The throttle disks 32 are passed through from both sides the springs 34 'to 34 "' held. The spring constant of all three springs 34 'to 34 "' is set here so that Movements both against and in the direction of flow of the fluid equally easily through the throttle washers 32 can be carried out. The throttle discs 32 have such a cross section that they are approximately the Adjusted contour of the cross section of the storage space 24 are. There is an opening in the middle of each throttle plate 32 36 provided through which fluid can flow.

Hydraulic fluid is now through the injectors 20th for example in a combustion chamber of a motor vehicle injected, this creates a vacuum wave that against the flow direction of the fluid in the Storage space 24 runs back. Through the vacuum wave the throttle disks 32 are created Pressure drop Δp across the throttle plate 32, which arises because the fluid and therefore the pressure through the Throttle disks are prevented from continuing to flow, against which Direction of flow of the fluid deflected, the spring 34 "'is compressed and the springs 34" and 34' stretched become. Part of the pressure energy is thereby in Implemented spring energy.

The pressure difference across the first throttle plate 32 then propagates and the second throttle plate 32nd achieved is clear in terms of its amplitude weakened. It leads to the second throttle disk 32 by the pressure drop Δp via the second throttle disk 32 compression of the spring 34 "and another Elongation of the spring 34 '. Through this movement the Throttle disc 32 becomes more pressure energy in spring energy converted, so that Δp = 0 prevails and there is no longer any pressure wave then propagate into common rail 10, for example would.

After the maximum of the pressure wave on the throttle discs has passed, the springs 34 give them in them stored energy back to the fuel, taking off the system moved back to the starting position. The system this causes the fuel to start vibrating acts as a further damper between the throttle disks 32. The single pressure vibration is hereby in one system superimposed vibrations implemented.

About the selection of the throttle discs 32 and the springs 34, as well as the respective parameters, the damping system to the different, for example fuel systems, be adjusted.

Claims (8)

High-pressure hydraulic accumulator, with a storage space (24) for a hydraulic fluid, and at least one connection (30) for the supply and discharge of the high-pressure hydraulic fluid from the storage space (24), wherein a vibration damping element in the storage space (24) (22) is arranged, characterized in that the vibration damping element (22) comprises at least one throttle disc (32) which is guided in the storage space (24) in the longitudinal direction of the storage space (24) in a resilient manner, the throttle disc (32) being a part of the cross section of the storage space, for the passage of the hydraulic fluid. High-pressure hydraulic accumulator according to claim 1, characterized in that the at least one throttle disc (32) has at least one bore, which is in particular arranged centrally High-pressure hydraulic accumulator according to claim 2, characterized in that the throttle disks (32) have a plurality of bores. High-pressure hydraulic accumulator according to one of Claims 1 to 3, characterized in that the throttle disks (32) are adapted to the inner contour and / or dimensions of the storage space (24) with regard to their outer contour and / or dimensions. High-pressure hydraulic accumulator according to one of the preceding claims, characterized in that a plurality of vibration damping elements (22) can be connected in series, the different vibration damping elements (22) having different damping parameters. High-pressure hydraulic accumulator according to one of the preceding claims, characterized in that the throttle disks (32) are arranged between two springs (34) which hold the throttle disk (32) in a basic position with constant pressure in the storage space (24), and depending on the direction of the occurring pressure difference allow a deflection of the throttle plate (32) in the longitudinal direction of the storage space (24). Use of a hydraulic high pressure accumulator after one of the preceding claims as High-pressure fuel storage for one Fuel injection system, the Vibration damping element (22) in a high pressure rail (10) and / or downstream to the high pressure rail (10) in a separate storage space (24) is arranged. Use of a hydraulic high pressure accumulator after one or more of the preceding claims in one Hydraulic system on test benches, in particular Flow test benches for injectors.

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