DEVICE FOR INFLUENCE, IN PARTICULAR REDUCTION, OF VIBRATIONS IN A FLUID SYSTEM AND METHOD FOR INFLUENCE, IN PARTICULAR REDUCTION, OF VIBRATIONS IN A FLUID SYSTEM

Description

[0001] The present application lies in the technical field of influencing, in particular reducing, vibrations in fluid systems, in particular hydraulic systems. In particular, the present application relates to a device for influencing, in particular reducing, vibrations in a fluid system, in particular a hydraulic system, comprising a separating means having one side for delimiting a fluid-conducting cavity of the fluid system. Furthermore, the application relates to a method for influencing, in particular reducing, vibrations in a fluid system.

[0002] Fluids (gases and liquids) are carried in many technical systems in pipes, lines, hoses or other cross-sections. The reasons for this are varied and depend on the respective technical system and its application. In many applications, unwanted vibrations occur, i.e. pressure fluctuations that are transmitted by the fluid. In some well-known hydraulic systems, the fluid used, e.g. water or oil, is used to transmit signals, forces or energy. Hydraulic systems are used, for example, in machines and systems (stationary hydraulics) or in mobile machines and vehicles (mobile hydraulics). As a rule, the lowest possible energy requirement to operate the hydraulic system is desirable, as are the lowest possible vibrations and noise emissions. Hydraulic systems usually comprise various components, such as pistons, motors, valves, accumulators and pumps.These components are usually connected to each other by hoses or cables.

[0003] The components of the hydraulic system can exhibit a certain degree of compliance with the fluid, which in some systems results in what is known as a swelling stiffness. The highest possible swelling stiffness, i.e. a low compliance of the components with respect to the fluid, is desirable for efficiency and dynamics, particularly for responsiveness and reaction speed. The fluids used are often considered incompressible as a first approximation, but in practice they exhibit a compliance which can be described by the compressibility (described by the bulk modulus) of the liquid. The swelling stiffness, the compliance of the fluid, and the moving masses (of the fluid or of the moving masses of components) result in an oscillating system with various resonances. This oscillating system is excited to oscillate, for example, by pumps or external influences.These vibrations typically have negative consequences, such as a shorter system lifespan, undesirable interference with system function, noise, and vibration transmission into the environment. Pressure peaks, in particular, can necessitate oversizing the system. For example, pumps typically excite the system at a frequency proportional to their speed or a multiple thereof. These excitations are generally predominantly harmonic. External influences can also result in broadband or pulse-like excitations.

[0004] There are various solutions in the state of the art for reducing the vibration problems in hydraulic systems described above. For example, diaphragm, piston, or bladder accumulators can be used to reduce vibrations. These are usually tuned to fixed frequencies. An additional volume is coupled for the respective fluid. In this volume, the fluid rests against a diaphragm, piston, or bladder. This, in turn, is usually supported by a gas volume to ensure a certain degree of compliance. This can reduce pressure or volume fluctuations in the hydraulic system. Unfortunately, such solutions usually require a comparatively large amount of installation space. Other solutions may provide for the use of flexible hoses, which result in low inflation stiffness and mitigate pressure peaks.However, this can result in lower energy efficiency and reduced hose durability. Other solutions utilize so-called side-branch or quarter-wave resonators, which comprise an additional line of defined length that is closed at one end. However, since the speed of sound in a hydraulic fluid depends on the respective pressure, optimal tuning of such resonators can be difficult, particularly when the quasi-static operating pressure of a hydraulic system changes during operation or for different operating states. Other solutions utilize Helmholtz resonators (analogous to vibration absorbers). Related prior art is described, for example, in WO 2012 / 163318 A1 and US Pat. No. 6,109,304 A. Adaptive or adjustable Helmholtz resonators (analogous to adjustable vibration absorbers) can be used in these cases.However, when using cylinders, especially as resonators, adequate sealing can be difficult. Furthermore, a volume change associated with adjusting the effective frequency can be problematic (pressure variations in the overall system, adjustment speed limited to avoid damage and undesirable effects on the hydraulic system). Furthermore, the force for adjustment must generally work against the hydraulic pressure, which necessitates comparatively large actuator forces. Such systems typically require comparatively high actuating forces and large installation spaces. Document EP 0 679 832 A1 describes a movable wall provided in a compensation volume connected to a line in order to reduce pressure pulsations in the line.

[0005] Against the background of the above-mentioned aspects, it is an object of the present application to propose an improved device for influencing, in particular reducing, vibrations in a fluid system, in particular a hydraulic system, which overcomes the described disadvantages of the prior art. In particular, it is an object to propose a device that enables rapid, reliable, and comparatively low-energy influencing, in particular reducing, vibrations. Furthermore, it is an object of the present application to propose a correspondingly advantageous method for influencing, in particular reducing, vibrations in a fluid system.

[0006] These objects are achieved by a device having the features of claim 1 and by a method having the features of a further claim. Advantageous further developments result from the features of the dependent claims and the exemplary embodiments.

[0007] The proposed device for influencing, in particular reducing, vibrations in a fluid system, in particular a hydraulic system, comprises a separating means having one side for delimiting a fluid-conducting cavity of the fluid system. The device also comprises a vibration-influencing unit, in particular a vibration-reducing unit, which is configured to mechanically adjust a stiffness of the separating means such that vibrations in the fluid system are influenced, in particular reduced. The vibration-influencing unit is generally a unit for influencing the dynamic properties. The separating means generally has its own stiffness (e.g., with respect to bending / deformation). It can therefore be provided that the vibration-influencing unit provides a resulting, joint stiffness of the separating means and the vibration-influencing unit.In embodiments in which elements other than the release agent also assume part of the release function, it is not necessary, but possible, for the release agent to assume a large part of the release function.

[0008] The mass of the fluid in the device, in combination with the separating agent and the vibration-influencing unit, results in an oscillating system that can be characterized by a tuning frequency. This tuning frequency changes by adjusting the stiffness using the vibration-influencing unit. Thus, the proposed device can reliably reduce harmonic, frequency-variable vibrations, such as those generated by pumps. This is especially true in the case of variable-speed pumps, where the tuning frequency is synchronized with the excitation frequency to be reduced. Furthermore, vibrations of the fluid system can be reduced at one of its natural frequencies. This is particularly advantageous for systems in which this natural frequency changes, for example, by connecting additional systems, and the tuning frequency of the device is synchronized accordingly.

[0009] In the proposed device, the stiffness is adjusted mechanically, for example, via a solid-state spring element. Thus, according to the proposed device, a gaseous component, e.g., a gas spring that changes the tuning frequency by changing the pressure, is not necessarily required to change the tuning frequency. Furthermore, comparable fluidic components for adjusting the stiffness are also not necessarily required, such as a fluid column whose volume is changed to change the tuning frequency, cf. a prior art adaptive Helmholtz resonator. Particularly compared to known adaptive Helmholtz resonators, the proposed device has the advantage that the fluid volume does not necessarily change to adjust the tuning frequency. Accordingly, no additional compensating measures are required in the overall hydraulic system.Furthermore, the proposed device enables rapid adjustment, as the device does not introduce any significant pressure changes into the hydraulic system during adjustment. Furthermore, in designs where static pressure compensation occurs, adjusting the natural frequency or tuning frequency does not require working against the pressure of the hydraulic system. This makes it possible to use an actuator or manual actuation device characterized by a small footprint to adjust the tuning frequency, for example, a comparatively small electric motor, particularly one with a gear transmission.In addition to the advantage of the small installation space, the proposed device has the advantage that the realizable frequency range is not limited, as is the case with conventional Helmholtz resonators, by the formation of standing waves within the chamber at a certain length of the resonator chamber.

[0010] The proposed device can thus be designed so that the stiffness of the separating agent can be adjusted by the vibration-influencing unit. The device thus ensures mechanical adjustability and adjustability of the stiffness of the separating agent by the vibration-influencing unit. The vibration-influencing unit thus allows the stiffness of the separating agent to be mechanically adjusted even after the device has been fully assembled. The vibration-influencing unit typically comprises a mechanical element. The stiffness is then typically provided by the mechanical element. Thus, the vibrations in the fluid system can be influenced by mechanically adjusting the stiffness.The proposed device is thus advantageous over known devices in which a spring arrangement is provided, but is permanently installed and not adjustable, i.e., adjustable. In such known devices, the spring arrangement, once selected and installed, no longer ensures adjustment of stiffness. As an example, reference is made in this context to the damping device shown in document DE 10 2015 013 281 A1.

[0011] The present application also relates to a correspondingly advantageous method for influencing, in particular reducing, vibrations in a fluid system, in which a device as described above or below is provided. Subsequently, the stiffness of the separating agent is adjusted by the vibration-influencing unit such that vibrations in the fluid system are reduced. Reducing vibrations within the meaning of this application also includes the complete damping of these vibrations so that no more vibrations occur. The proposed device can generally be used to influence vibrations or to influence the dynamic behavior (vibration behavior) of the fluid system or hydraulic system.

[0012] In typical embodiments, the vibration-influencing unit comprises a solid-state spring element. The solid-state spring element can, for example, form part of the separating agent, be connected to the separating agent, or be in contact with it. The solid-state spring element can, for example, be made of metal, plastic, and / or wood. The solid-state spring element can be fiber-reinforced. The solid-state spring element can, for example, be supported on one side. In some embodiments, the solid-state spring element is a bending beam. The adjustability of the stiffness can be achieved by changing the free length of the bending beam using a suitable vibration-influencing unit.

[0013] According to the invention, the vibration control unit is configured to adjust the stiffness of the separating agent through a rotational movement. This ensures good operability of the vibration control unit, both manually and automatically, while maintaining a compact design.

[0014] In typical embodiments, the vibration influencing unit for mechanically adjusting the stiffness comprises mechanical means which are or can be mechanically coupled to the release agent, usually to a side of the release agent facing away from the fluid-carrying cavity or, in possible embodiments, to a side of the release agent facing the fluid-carrying cavity, so that the adjustment of the stiffness is achieved by moving the mechanical means.

[0015] In some embodiments, the vibration-influencing unit has connections. To adjust the rigidity, the connections can be in contact with the release agent, in particular with a side of the release agent facing away from the fluid-conducting cavity, or can be brought into contact, and / or can be rigidly connected or connectable. For example, the rigidity can be adjusted by moving the connections relative to the release agent. Additionally or alternatively, the rigidity can be adjusted by moving components that are directly or indirectly in contact with the connections relative to the connections.

[0016] In particularly preferred embodiments, the vibration-influencing unit comprises at least one spring ring and a connection holder rotatably mounted relative to the spring ring. The spring ring can be designed in one or more parts in various designs. The spring ring can be in contact with the release agent via connections that are fixedly connected to the spring ring. In addition, the connection holder can be in contact with the spring ring via connections that are fixedly connected to the connection holder. In this way, a precise adjustment of the stiffness can be easily achieved by rotating the connection holder relative to the spring ring. The connection holder and / or the spring ring can be designed as part of a plate- or ring-shaped component.

[0017] By rotating the connection holder relative to the spring washer, the contact areas where the connections come into contact with the release agent and / or the connection holder and / or the spring washer are changed. This can change the surface elasticity acting transversely to the release agent. If the connections that are fixedly connected to the connection holder overlap with the connections that are fixedly connected to the spring washer, the effective surface stiffness of the release agent is generally at its greatest. If the contact points of the connections are moved into positions with mutual distance angles due to the relative rotation of the spring washer and the connection holder, the surface stiffness acting transversely to the release agent is reduced down to the largest possible distance angle at which the surface stiffness is minimized.To vary the stiffness of the release agent, it is therefore only necessary to rotate the spring ring relative to the connection holder.

[0018] In some embodiments, the device is configured to allow manual adjustment of the stiffness. Additionally or alternatively, the stiffness adjustment can be performed automatically, for example, by an electric motor.

[0019] The device typically comprises a housing. In this case, the connection holder is rotatable relative to the housing in typical designs. The separating means is generally secured against rotation relative to the housing. For example, the device can be configured to allow manual rotation of the connection holder. In this case, the stiffness and tuning frequency can thus be adjusted particularly easily by a user. A motor can also be provided in some designs. The motor can be configured to cause the connection holder to rotate relative to the housing. In this design, the stiffness can be controlled automatically in a particularly simple manner.

[0020] In some designs, a device is provided for compensating the static pressure components. This device can be operated manually or automatically. This device can, for example, comprise a spring and / or a second cavity in contact with the release agent, as explained in more detail below. In the case of a second cavity, the static pressure components can be compensated by adjusting the gas pressure in the second cavity.

[0021] In some embodiments, the separating means is a membrane or a bladder. However, in many embodiments, the separating means is a piston. In typical embodiments, it is also provided that the separating means is mounted so as to be translationally movable. According to this example, the device can compensate for the static pressure of the fluid and, in particular, can be designed to store energy by compressing the gas in a second cavity described in more detail below. It can further be provided that the device has a spring, in particular a helical spring. The spring can press on a side of the separating means facing away from the fluid-conducting cavity and / or facing the fluid-conducting cavity in such a way that a static pressure in the fluid-conducting cavity is compensated by deformation of the spring and displacement of the separating means.Some designs feature adjustable spring preload. This allows for adaptation to different static pressure components.

[0022] In typical embodiments, the separating means separates the fluid-conducting cavity from a second cavity. In most embodiments, the vibration-influencing unit is at least partially arranged in the second cavity. The second cavity can, for example, be gas-filled, in particular air-filled. Typically, the second cavity can be pressurized. For example, the second cavity can be sealed gas-tight or lockable. In this way, the second cavity enables an additional option for adjusting the tuning frequency by adjusting the pressure in the second cavity. In addition, a gas volume in the second cavity can act as an air spring. For example, the second cavity can be connected to a valve. The valve can be in fluid communication with the second cavity and can be part of the device.The provision of the valve provides an additional option for adjusting the degree of damping. The valve can be adjustable, in particular by adjusting the flow cross-section.

[0023] In some embodiments, the device has a second separating means. The second separating means can be translationally displaceable. Furthermore, the second separating means can separate the second cavity from a third cavity. It can be provided that the third cavity is in fluid communication with the fluid-conducting cavity, in particular via a connecting line. The connecting line can have a smaller cross-section than the fluid-conducting cavity and in particular than the second and / or the third cavity. In this way, automatic compensation of the static component of the pressure in the fluid can be achieved. It can also be provided that the connecting line has a valve, in particular a throttle valve, or a shut-off valve.

[0024] In some embodiments, the fluid-conducting cavity encloses a line of the fluid system, in particular concentrically. For example, it can be provided that the fluid-conducting cavity surrounds the line by an angular range of at least 90 degrees, at least 180 degrees, at least 270 degrees, or completely circumferentially. The fluid-conducting cavity and / or the line can be part of the claimed device. This embodiment is characterized by a highly integrated design and is thus very space-saving. As a rule, it is provided that the fluid-conducting cavity and the line are in fluid communication with each other via openings. The opening cross-sections of these openings can be adjustable in some embodiments. The separating agent in this embodiment is usually annular.

[0025] In some embodiments, it is provided that the separating means has a translationally displaceable first separating means section. In addition, the separating means can have a translationally displaceable second separating means section. The second separating means section can be translationally displaceable relative to the first separating means section. In addition, a seal can be formed between the first and second separating means sections. The vibration-influencing unit can be connected to the first separating means section and to the second separating means section such that the vibration-influencing unit acts between the first separating means section and the second separating means section and is translationally displaceable with the first separating means section and the second separating means section.As a rule, the first separating means section, the second separating means section, and the vibration-influencing unit are mounted so as to be displaceable relative to the housing of the device, in particular so as to be translationally displaceable. The vibration-influencing unit is generally supported on the first and second movable separating means sections, in particular without the need to support the vibration-influencing unit on the housing. As a result, the vibration-influencing unit itself or parts thereof are not deflected by static pressure components, so that the stiffness setting is not influenced by the static pressure components. Thus, the vibration-influencing unit can be specifically tailored to the dynamic pressure fluctuations to influence and, in particular, reduce the vibrations in the fluid system.It can further be provided that a sealing area between the separating agent and the housing has a particularly increased, for example, adjustable, breakaway torque. As a rule, the sealing area between the separating agent and the housing has increased friction compared to the seal between the separating agent sections. This and / or a significantly lower mass inertia of the first separating agent section compared to the second separating agent section is generally provided.

[0026] In some embodiments, the device comprises a control unit. The control unit can be connected to the vibration-influencing unit for adjusting the stiffness in such a way that the stiffness can be adjusted by the control unit. In this case, the control unit can be configured to adjust the stiffness based on acceleration sensor signals and / or pressure sensor signals and / or a pump speed and / or based on virtually calculated signals and / or displacement variables and derived variables, such as accelerations. In this way, the device is suitable for automatically reducing vibrations by automatically adjusting the tuning frequency. It can be provided that the control unit is configured to output a control signal to the vibration-influencing unit and in particular to an adjustment actuator system thereof, in particular to the motor.The tuning frequency can be adjusted by adjusting the stiffness of the control unit to the pump speed and / or a multiple thereof. The acceleration sensor signal and / or pressure sensor signal is generally output by a sensor directly or indirectly connected to the fluid. The control unit can be configured to convert the acceleration sensor signal and / or pressure sensor signal into the frequency domain, in particular by Fourier transformation. The tuning frequency can be adjusted by adjusting the stiffness of the control unit to this frequency signal. It can also be provided that the control unit is configured to adjust the stiffness based on signals from two acceleration or pressure sensors. The sensors can be configured to measure the acceleration or pressure at locations in the fluid system between which the fluid-conducting cavity is arranged.The signals from these sensors can be converted into the frequency domain by the control unit. The tuning frequency can then be adjusted by adjusting the stiffness to reduce the transmission of the frequency components to be reduced between the sensors.

[0027] The device can also comprise a coupling sensor. The coupling sensor can be configured to detect the coupling of another component to the fluid system. Furthermore, the control device can be provided and configured to adjust the stiffness based on a signal from the coupling sensor. In this way, changes in the fluid system's natural frequency resulting from the coupling of the other component can be easily and quickly taken into account when influencing or reducing the vibrations. In a method for influencing vibrations in the fluid system, the stiffness of the separating means can thus be adjusted based on the signal from the coupling sensor.

[0028] The device can also comprise an actuator, in particular one connected to the separating agent. The actuator can be configured to actively introduce forces into the fluid, in particular by moving, for example, causing the separating agent to oscillate. The actuator can also be used to specifically reduce vibrations in the fluid system and / or transmit signals. For example, the actuator can be configured to cause the separating agent to oscillate. In typical embodiments, the actuator comprises a moving coil actuator and / or a piezo actuator. In typical embodiments, the actuator is connected to the control unit and can be controlled by it.

[0029] The fluid is preferably largely incompressible and can, for example, be hydraulic fluid, oil, or water. In principle, however, the use of some embodiments of the device is also possible in systems with a compressible fluid, for example air or gas. The fluid system can, for example, be a mobile or stationary hydraulic system. For example, the fluid system can be or comprise a hydraulic drive or a pump. Furthermore, the fluid system can be or comprise a water line system. In addition, the fluid system can be or comprise a fuel injection system, in particular of engines. Furthermore, the fluid system can be or comprise an intake manifold of an internal combustion engine, wherein the cavity can be arranged on the intake manifold. In addition, the fluid system can be or comprise an air supply of a turbocharger, wherein the cavity can be arranged on the air supply.In addition, the fluid system can be an exhaust system or comprise an exhaust system, in particular between a cylinder and an exhaust gas turbocharger, wherein the cavity can be arranged on the exhaust system.

[0030] The present application may also relate to the fluid system, in particular the hydraulic system. The fluid system may comprise the device described above or below. Furthermore, the fluid system may contain, for example, a pump and / or a consumer, in particular a hydraulic consumer. Additionally or alternatively, the fluid system may contain a line that, in some embodiments, connects the pump to the consumer. The fluid-conducting cavity may be in fluid communication with the line. In some embodiments, the separating means is arranged on the line.

[0031] Features mentioned above or below with respect to the device for influencing, in particular reducing, vibrations in the fluid system or the fluid system are correspondingly applicable to the method and vice versa.

[0032] Examples of implementation are described below using the figures. Figs. 1(a) to (d) show possible arrangements of a device for reducing vibrations in a fluid system, Fig. 2 shows a schematic view of the device, Fig. 3 shows a partially perspective view of the device, Fig. 4 shows a cross-sectional view of the device, Fig. 5 shows a perspective view of a vibration reduction unit, Fig. 6 shows a cross-sectional view of the device, Figs. 7(a) and (b) show various schematic views of a device according to a further embodiment, Fig. 8 shows a cross-sectional view of the device according to a further embodiment, Figs. 9(a) to (c) show schematic views of the device according to a further embodiment, Fig. 10 shows a schematic cross-sectional view of the device according to a further embodiment, and Figs. 11 and 12 show various fluid systems with the proposed device.

[0033] Figures 1(a) to (d)show schematic arrangements of a device 1 for reducing vibrations in a fluid system, in particular a hydraulic system. However, this device 1 can also be used in general to influence vibrations in the fluid system. This device 1 allows the dynamic properties of the fluid system to be adjusted. Fig. 1(a) shows the integration of the device 1 into a linear line 3 of the hydraulic system, which is designed as a hose or channel. The line 3 carries a fluid or hydraulic liquid 2, but in other designs can also carry a gas. Fig. 1(b) The device is fluidically connected to a bend in line 3. Recurring features are provided with the same reference numerals in this and the following figures. Fig. 1(c)is a schematic structural integration of the device 1 into a housing 4 of another component, for example the housing of a pump (not shown) or a control or valve block. Figure 1(d) schematically shows an embodiment of the device 1 arranged concentrically around the line 3, which is described in more detail below. This concentric arrangement is also possible within a housing 4, for example, within a pump housing.

[0034] Figure 2shows a schematic of the structure of a proposed device 1. The device 1 comprises a housing 13. Within this housing 13 there is a fluid-conducting cavity 10, i.e. a volume that can be filled with the fluid 2. The fluid-conducting cavity 10 can be separated from a second cavity 14, i.e. a further volume, by a separating means 11 (e.g., piston, diaphragm, bladder). In typical embodiments, the volume 14 is gas-tight and can be pressurized via, for example, a valve 20. In the basic features described so far, the device is comparable to a piston, diaphragm, or bladder accumulator (also called an "accumulator") known from the prior art. However, the proposed device 1 has a vibration-influencing unit designed as a vibration-reduction unit 12, which acts on the separating means 11, i.e., has an adjustable stiffness.This structure, with the (proportional) mass of the fluid in the device 1 in combination with the vibration reduction unit 12 or adjustable stiffness, results in an oscillating system that can be characterized by its tuning frequency. This tuning frequency changes by changing the stiffness of the separating agent by mechanical adjustment via the vibration reduction unit. Furthermore, the tuning frequency can also be specifically influenced by the targeted selection or modification of the mass of the separating agent 11. In some embodiments, the device 1 has the following sensors: a pressure sensor (not shown) in the volume 10, a displacement / speed or acceleration sensor on the separating agent 11 and / or on the housing 13, and / or a temperature sensor on the housing 13 or in the volume 10.

[0035] Figure 3shows a partly schematic, partly perspective view of the device 1 on a - simplified representation - hydraulic system that contains a pump A, a system of several lines 3 and hydraulic consumers B (e.g. cylinders or actuators). If a variable-speed pump A generates pressure pulsations with a certain, speed-dependent frequency, the device 1 can be used to reduce these vibrations. The device 1 then functions analogously to a vibration absorber. For this purpose, the tuning frequency of the device 1 is adjusted by adjusting the vibration reduction unit or adjustable stiffness 12 so that it falls as far as possible on the frequency to be absorbed. If the tuning frequency of the device 1 is varied along with the changing speed of the pump A, the device functions analogously to a neutralizer.

[0036] In Fig. 4 shows the Fig. 3A schematic cross-section of a device 1 shown therein. The fluid 2 transported from the hydraulic system via line 3 fills the fluid-conducting cavity 10 in the housing 13 of the device. The fluid-conducting cavity 10 is separated from the second cavity or second volume 14 by a separating means 11 in the form of a piston. This second volume can be gas-tight and can be filled with a gas, for example, through the valve 20. The filling pressure in the second cavity 14 can be used to compensate for a static pressure component in the fluid 2. When selecting the gas pressure required for the volume 14, the ratio of the effective areas of the piston 11 to the volumes 14, 10 must be taken into account. If the valve 20 is connected to another gas volume and if the cross-section of this valve is adjustable, this valve can also be used to adjust damping.The piston 11 is mounted for translational movement along the main axis 125 of the device 1. In the example shown, the piston 11 is also secured against rotation about this main axis 125.

[0037] In addition, the piston 11 is connected to the vibration reduction unit 12, ie the device for realizing an adjustable stiffness. A possible implementation of the vibration reduction unit 12 is shown schematically in Fig. 5shown. The vibration reduction unit 12 has a spring ring 121, for example made of metal, plastic, or fiber-reinforced material, and also three connections 122, which are rotatably attached to the piston 11 at a pitch of, for example, 120° (or, for example, 90° in the case of four connections per side). Furthermore, the connections 122 are fixedly connected to the spring ring 121. On the opposite side of the spring ring, three further connections 123 are arranged, which are fixedly connected to a connection holder 124 at a pitch of 120°. The connection holder 124 is rotatably mounted relative to the housing 13 about the main axis 125. This allows an angle 126 to be set between the connections 122 on the top side and the connections 123 on the bottom side. This determines the stiffness of the adjustable spring element in the direction of the main axis 125.

[0038] If the outer surface of the connection holder 124 is provided with a suitable toothing (not shown), this can be used in combination with a worm 40 (see Fig. 3 and 4 ) can be used to rotate the connection holder 124 and thus adjust the stiffness and the associated tuning frequency of the device 1. Manual adjustment of the stiffness and thus manual adjustment of the tuning frequency, for example, by manually rotating the device 1 once to adjust the stiffness, is possible.

[0039] Figure 6illustrates an embodiment in which a static pressure component of the fluid 2 in the fluid-conducting cavity 10 is absorbed by a spring 30, in particular a helical spring. In this case, the second cavity 14 is not gas-tight. Furthermore, a device 31 known per se and not further detailed here can be integrated, which allows for the adjustment of a preload on the helical spring 30. This enables adaptation to different static pressure components. A valve 20 (not shown here) between the volume 14 and the ambient atmosphere can be used to adjust the degree of damping of the device, cf. the above explanations regarding Fig. 4 .

[0040] Figures 7(a) and (b)show a further variant of the device 1 described above. The fluid-carrying cavity 10 or the fluid volume is separated, as described, by the piston 11 from the second cavity 14 or the gas volume, which can be filled via a valve 20. The vibration reduction unit 12 or adjustable stiffness is also supported on the housing 13 as usual. A further separating means 16 or another piston is arranged in series with the gas volume 14. This separates the gas volume 14 from a third cavity 15 or another fluid volume. The volumes 10, 15 are connected via a connection 18. The purpose of this connection 18 is to automatically equalize the static pressure component in the fluid. For this purpose, the cross-section of the connection can either be very small, or a further measure 30 can be integrated into the connection 18, see Fig. 7(b)This measure 30 can be, for example, a throttle, a valve, or a shut-off valve. The latter can, for example, be opened at specified times or at times initiated by a control unit to equalize the pressure between volumes 10, 15.

[0041] Figure 8 shows a further embodiment of the device 1, in which the fluid-carrying cavity 10 or the fluid volume is separated from the second cavity 14, ie from the volume 14, by means of a membrane M and a separating means 11 in the form of a plate 11. According to the previous examples, the volume 14 can be gas-tight and used to compensate for static pressure components in the fluid 2 and / or in the chamber 10. In the example shown, to realize the adjustable stiffness 12, the Fig. 5The vibration reduction unit shown is used. The three connections 122 are each rotated by 120° and fixedly attached to the plate 11 and connected to the spring ring 121. This is connected on the opposite side to the three connections 123, which are rotated by 120° and fixedly connected to the connection holder 124. The connection holder 124 is mounted relative to the housing 13 in such a way that it has one degree of freedom. The connection holder 124 can be rotated about the main axis. If the connection holder 124 is provided with a toothing on the inside, the stiffness of the vibration reduction unit 12 (shown in the form of the individual components 121, 122, 123 and 124) can be adjusted with the aid of a motor 42, which engages the internal toothing of the connection holder via a shaft and another gear 41.Furthermore, an actuator 98 in the form of a moving coil actuator, comprising a coil 44 and a magnet 43, is integrated into the device 1. The moving coil actuator enables—with the aid of a suitable power amplifier, appropriate signal processing in a control unit, and sensors—to actively introduce forces into the fluid 2.

[0042] Figures 9(a) to (c)schematically illustrate a further embodiment of the device 1, which can be particularly advantageous when tight installation spaces or a highly integrated design is desired or required. In this case, the housing 13 is designed, preferably concentrically, as part of the line 3 or the hose. The fluid 2 can thus flow through the device 1. The fluid-carrying cavity 10 or the fluid volume 10 is arranged concentrically around the line 3. The volume 10 is connected to the line 3 through openings 99 in this line. These openings can be rectangular, as shown, but can also have various other shapes or cross-sections. In particular, these cross-sections can also be adjustable, for example by means of slides or diaphragms (not shown). The separating means 11 or the piston 11 here also separates the fluid volume 10 from the second cavity 14 or the further volume 14 and is supported on the vibration reduction unit 12 oradjustable stiffness, which in turn is supported on the housing 13, which in the embodiment shown is designed as a component of the line 3. . Figure 9(c) shows an area of ​​the embodiment in greater detail.

[0043] The fluid volume 10 is separated from the volume 14 by the piston 11, which is also arranged concentrically to the line. This can also be optionally gas-tight in this embodiment and in this case, e.g. via a valve 20, can be pressurized to compensate for static pressure components in the fluid 2. The piston is supported by the adjustable stiffness 12, which is also exemplary here according to Fig. 5is realized. In the example shown here, the necessary rotation of the connection holder can be carried out via the schematically indicated worm gear, comprising the combined connection holder 124 with the worm wheel 124 and the worm including the drive shaft 40, by means of which the rigidity is adjusted. Analogous to Figs. 7(a) and (b) the structure is made of Figs. 9(a) to (c) also conceivable with a second separating means 16 and a second fluid chamber 15, which is connected to the volume 10 by a connection 18 for pressure equalization. With a corresponding design, this connection 18 for pressure equalization can also be created between the fluid chamber 15 and the fluid 2 in the line 3 or in the pipe, for example, through a radial bore at the level of the chamber 15.

[0044] Figure 10shows schematically a further example of an embodiment of the device 1. The housing 13 of the device 1 is connected directly or indirectly (e.g. by screwing) to the pipe / line 3. The fluid-carrying cavity 10 or the fluid volume 10 and the second cavity 17 or the volume 14 are separated from one another in this embodiment by two separating means sections 111 and 11. In the example shown, these separating means sections 111, 11 are both designed as pistons, but in particular the first separating means section 11 can also be designed as a membrane. The second separating means section 111, in particular piston 111, is mounted so as to be movable relative to the housing 13 in the direction of the main axis. In this case, a sealing area 112 between the piston 111 and the housing 13 is preferably designed such that it has a defined breakaway torque. In a particularly preferred embodiment, this breakaway torque is adjustable.The piston 11 is mounted so as to be movable relative to the piston 111 in the direction of the main axis of the device. The seal 113 between the two pistons 111 and 11 is preferably designed to have the lowest possible friction. The vibration reduction unit 12 or adjustable stiffness 12 supports the piston 11 relative to the piston 111 by means of the connection 212. The volume 14 is gas-tight and pressurized. This volume thereby functions as an air spring. If the static pressure component in the fluid 2 and thus the fluid volume 10 changes, the entire structure consisting of the two pistons 11 and 111 as well as the adjustable stiffness 12 shifts relative to the housing 13. The breakaway torque between the piston 111 and the housing 13 determines the pressure difference between the volumes 10 and 14 at which the structure shifts.As a result, the adjustable stiffness 12 is not deflected by static pressure components, but only by the dynamic pressure fluctuations.

[0045] How Fig. 10 As shown, in the device according to the invention, a structural separation between the fluid 2 and the fluid volume 10 is not absolutely necessary. In Helmholtz resonators according to the prior art, however, a so-called neck is necessary to provide an oscillating mass for the resonator. In contrast, in the proposed device 1, this mass can also be provided by the mass of the separating agent 11. As already explained above, the illustrated embodiment is suitable for the automated compensation of static pressure components.

[0046] Figure 11shows a schematic representation of a hydraulic system with a device 1 according to the invention and a control system for operating the device. A control unit 70 is used to adjust the tuning frequency of the device 1. For this purpose, the control unit 70 sends a suitable signal 71 to an adjustment actuator integrated in the device 1 (see, for example, servo motor 42 in Fig. 8) in order to adjust their tuning frequency. The tuning frequency of the device 1 can, for example, be generated by the control unit 70, regulating or control device, based on a speed signal 73 (or a part or a multiple thereof) that is output by a pump A or measured thereon. The tuning frequency of the device 1 can, for example, also be generated by the control unit 70, regulating or control device, based on an acceleration or pressure value 74 that is measured on the line 3 or on the hose by a suitable acceleration or pressure sensor 80. The signal 74 can be converted into the frequency domain in the control unit 70, for example by an FFT (fast Fourier transformation). The tuning frequency of the device 1 can be selected by the control unit 70 based on this frequency signal.The tuning frequency of the device 1 can, for example, also be generated by the control unit 70, the regulating or control device, based on two acceleration or pressure values ​​74, 75, which are recorded by suitable sensors 80, 82 and converted into the frequency domain in the control unit 70. The tuning frequency 71 is set, for example, such that the transmission of the disadvantageous frequency components to be reduced between 80 and 82 is reduced as much as possible.

[0047] Furthermore, the integration of an actuator 98 as described above (for example, a moving coil actuator or piezo actuator) is possible in all embodiments. The actuator can be supported between the separating means 11 and the housing 13. Additionally or alternatively, the actuator can be supported between a first separating means section 11 and a second separating means section 111, see Fig. 10. The actuator acts in the direction of movement of the separating agent 11. This allows forces to be actively introduced into the fluid. If the actuator 98 is provided for the active introduction of forces into the fluid, it can additionally be used to reduce vibrations in the fluid. This actuator can be controlled by the control unit 70 using suitable power electronics. The control signal 97 can be calculated based on a transformation of the acceleration and pressure values ​​74 using a carrier frequency method with quadrature mixing. The carrier frequency corresponds to an order of the speed signal. The tuning frequency can then be determined by comparing the phase position between the dynamic pressure curves on the line 3 and the phase position of the diaphragm deflection. The actuator 98 can also be controlled via a control device implemented in the control unit 70. In the case of periodic pressure excitation, e.g.Due to multiple harmonics of the rotational speed, the actuators can also be controlled via an adaptive counter-control (e.g., FxLMS). Here, sensors 80, 82 can optionally be used to implement a wave separation method that enables differentiation between forward and backward wave fronts in line 3 or in the hose. Actuator 98 can also be controlled via a state or output feedback, whereby the coupled dynamic behavior of the line / hose system can be adjusted using control technology with device 1. Figure 12shows a schematic representation of a hydraulic system with the proposed device 1, wherein the possibility exists of coupling a further hydraulic component C to the fluid system. The device 1 is arranged in a (not fully shown) hydraulic system which contains a pump A and further components B. In addition, the system contains at least one coupling or connection which makes it possible to connect the further hydraulic component C or further hydraulic systems. By connecting the further component C or the further system, the dynamic properties of the entire hydraulic system change. The hydraulic system contains a coupling sensor 78 which detects the connection of the further component C and transmits this information 79 to the control unit 70.Based on this, the latter can send control signals 71, 72 to the device 1 to change its tuning frequency and / or—for example, with a pump 90—to adjust the pressure in volume 14. This makes it possible to detune the hydraulic system and avoid unfavorable combinations of natural frequencies that can arise when coupling one hydraulic system to another hydraulic system C. This can happen, for example, when coupling implements to agricultural machines such as tractors.

Claims

1. A device (1) for influencing, in particular reducing, vibrations in a fluid system, in particular a hydraulic system, comprising a separating means (11) which has a side for delimiting a fluid-conducting cavity (10) of the fluid system, comprising a vibration-influencing unit (12), which is designed to mechanically adjust the rigidity of the separating means (11) such that vibrations in the fluid system are influenced, in particular reduced, characterized in that the vibration-influencing unit (12) is designed to adjust the rigidity of the separating means (11) by means of a rotational movement.

2. The device (1) according to claim 1, characterized in that the vibration-influencing unit (12) comprises a solid-body spring element.

3. The device (1) according to any of claims 1 or 2, characterized in that the separating means (11) is mounted so as to be translationally movable.

4. The device (1) according to claim 3, characterized by a spring (30), which presses on a side of the separating means (11) facing away from the fluid-conducting cavity (10) and / or facing the fluid-conducting cavity such that a static pressure in the fluid-conducting cavity (10) is compensated for by deforming the spring (30) and displacing the separating means (11).

5. The device (1) according to any of claims 1 to 4, characterized in that the separating means (11) separates the fluid-conducting cavity (10) from a second cavity (14), wherein, in particular, a static pressure in the fluid-conducting cavity (10) is compensated for by adjusting the gas pressure in the second cavity (14).

6. The device (1) according to claim 5, characterized by a second separating means (16), which is translationally displaceable and separates the second cavity (14) from a third cavity (15), the third cavity (15) being in a fluid connection to the fluid-conducting cavity (10).

7. The device (1) according to any of claims 1 to 6, characterized in that the device (1) is suitable for influencing, in particular reducing, vibrations in a fluid system, in which the fluid-conducting cavity (10) surrounds a line of the fluid system, in particular concentrically.

8. The device (1) according to any of claims 1 to 7, characterized in that the vibration-influencing unit (12) comprises a spring washer (121) and a connector retainer (124) mounted so as to be rotatable relative to the spring washer (121), the spring washer (121) being in contact with the separating means (11) via connectors (122) connected to the spring washer (121) in a stationary manner and the connector retainer (124) being in contact with the spring washer (121) via connectors (123) connected to the connector retainer (124) in a stationary manner.

9. The device (1) according to claim 8, characterized by a housing (13), the connector retainer (124) being rotatable relative to the housing (13), and characterized by a motor (42), which is designed to bring about a rotation of the connector retainer (124) relative to the housing (13).

10. The device (1) according to any of claims 1 to 9, characterized in that the separating means (11) comprises a translationally displaceable first separating means portion (11) and a translationally displaceable second separating means portion (111), the second separating means portion (111) being translationally displaceable relative to the first separating means portion (11) and a seal (113) being formed between the first and the second separating means portion (11, 111), the vibration-influencing unit (12) being connected to the first separating means portion (11) and the second separating means portion (111) such that the vibration-influencing unit (12) takes effect between the first separating means portion (11) and the second separating means portion (111) and is translationally displaceable together with the first separating means portion (11) and the second separating means portion (111), a sealing region (112) between the separating means and the housing in particular having an in particular increased, for example adjustable, breakaway torque.

11. The device (1) according to any of claims 1 to 10, characterized by an actuator system (98) which is connected to the separating means (11) and is designed to bring about vibration of the separating means (11).

12. The device (1) according to any of claims 1 to 11, further comprising a control unit (70), which is connected to the vibration-influencing unit (12) for adjusting the rigidity such that the rigidity can be adjusted by the control unit (70), the control unit (70) being designed to adjust the rigidity on the basis of acceleration sensor signals and / or pressure sensor signals and / or a pump speed.

13. The device (1) according to any of claims 1 to 12, characterized by a coupling sensor (78), which is designed to detect a further component (C) being coupled to the fluid system, a control apparatus (70) being provided and designed to adjust the rigidity on the basis of a signal from the coupling sensor (78).

14. A method for influencing, in particular reducing, vibrations in a fluid system, in particular a hydraulic system, comprising: - providing a device (1) according to any of the preceding claims, and - adjusting the rigidity of the separating means (11) by means of the vibration-influencing unit (12) such that vibrations in the fluid system are reduced.

15. The method according to claim 14, characterized in that the device (1) is a device according to claim 13, in which the rigidity of the separating means (11) is adjusted on the basis of the signal from the coupling sensor (78).