DE102011081496A1 - Hydraulic vibration damper i.e. monotube damper, for frequency damping of vibrations of wheels in e.g. motor car, has slide valve that comprises borehole corresponding with pre-opening, and slidably arranged inside piston valve - Google Patents

Abstract

The damper i.e. monotube damper (D1), has a reservoir tube (5) in which a piston rod (6) is slidably arranged with a piston. A piston valve (8a) comprises discharge openings (1', 7') and a pre-opening (3) for changing damping medium between working chambers (90a, 90b). The pre-opening is lockable by a slide valve (2). The slide valve comprises a borehole (2a) corresponding with the pre-opening. The slide valve is slidably arranged inside the piston valve and in a fluid-tight recess (20). Another borehole is axially arranged in the slide valve.

Description

The invention relates to a hydraulic vibration damper, in particular for motor vehicles, comprising a cylinder in which a piston rod is slidably disposed with a piston and a valve, wherein the valve has at least one passage opening and at least one pre-opening for exchange of damping medium between a first working space and a second working space and wherein the pre-opening is closable by means of a closing element.

Although applicable to any hydraulic vibration damper, the invention will be explained with reference to hydraulic vibration dampers in automobiles.

Hydraulic vibration dampers are used to reduce unwanted vibrations of the wheel and the construction of a motor vehicle. A damping force of the hydraulic vibration damper is generated via a pressure difference between valve components of the vibration damper and is dependent on the relative speed between the wheel and the structure of the motor vehicle. For high driving safety, for example, it is desirable to provide a high damping of the first natural frequency of the unsprung mass of the axle in the frequency range between approximately 10-14 Hz. The vibrations of wheels thus quickly decay and a fluctuation of the ground force, that is the contact force between the wheel and the ground, is reduced. A necessary transmission of braking and cornering forces between the ground, wheel and body of the motor vehicle is guaranteed.

In order to enable a comfortable driving of the motor vehicle, however, a low vibration load of the structure of the motor vehicle in the region of the respective body natural frequency, usually between about 0.9 and 1.6 Hz and in the particular vibration sensitive frequency range between about 4- 8 Hz desirable. A damping of the hitherto conventional hydraulic vibration damper, however, can not be adjusted frequency selective: With a strong damping of the natural frequencies of body and wheel a known vibration damper acts in human-sensitive vibration range 4-8 Hz as a "shock amplifier" and thus significantly reduces the ride comfort.

From the DE 27 58 083 A1 is a frequency-dependent vibration damper, in particular for a washing machine, has become known with a cylinder at least partially filled with liquid, in which a, attached to a piston rod and provided with damping means piston is guided displaceably. To bypass the damping devices arranged on the piston, the piston rod has an axial bore into which opens at least one essentially radially opening, in the region of which a mass connected via a spring to the piston rod or the piston is displaceably arranged on the piston rod. To limit the axial movement of the mass at least one hydraulically acting damping device is provided, wherein the mass itself is a part of this damping device.

A disadvantage is that on the one hand the hydraulic vibration damper requires a lot of space, on the other hand, the damping essentially depends on the first natural frequency of the mass, that is, the damping effect of the hydraulic vibration damper decreases in the natural frequency of the mass.

An object of the present invention is therefore to provide a reliable and compact hydraulic vibration damper, which enables a more targeted damping of predefinable frequency ranges.

The invention solves the problem with a vibration damper, in particular for motor vehicles, comprising a cylinder in which a piston rod is slidably disposed with a piston and a valve, wherein the valve has at least one passage opening and at least one pre-opening for the exchange of damping medium between a first working space and a second working space and wherein the pre-opening is closable by means of a closing element, characterized in that the closing element has at least one first bore which corresponds to the pre-opening, and in that the closing element is arranged slidably in the interior of the piston valve.

The object is also achieved by a motor vehicle having a vibration damper according to at least one of claims 1 to 11.

The problem is finally solved by the use of a vibration damper for frequency-dependent damping of vibrations in household appliances, especially washing machines and / or in land, air or water vehicles, especially in motor vehicles.

Due to the arrangement of the closing element in the interior of the piston, the vibration damper can be made substantially more compact overall. In addition, an attenuation for a specific frequency band in the region of the first natural frequency of the closing element is increased by the vibration damper proposed according to the invention. This is a more targeted damping a certain frequency or a frequency range possible.

Further advantageous embodiments, features and advantages of the invention are described in the subclaims.

Vorteilhalterweise the valve is a piston valve.

Conveniently, the closing element in the valve, in particular two-sided, is spring-mounted. By means of the resilient mounting a resonant frequency of the closing element, in particular to a natural frequency of the structure or the axis of the motor vehicle can be tuned so that the vibration comfort of the motor vehicle is improved. If the closing element is in particular resiliently mounted on two sides, the possibilities for adapting the hydraulic vibration damper to a desired behavior are further increased since, for example, springs with different spring constants, material, etc. can be adapted or used depending on the area of application and desired requirements.

Advantageously, the closing element is arranged in the valve in a fluid-tight recess. The advantage thus achieved is that the closing element does not interact with the damping medium in the cylinder of the hydraulic vibration damper. Negative influences of the damping medium in the cylinder, such as an undesirable change in the Dämpffrate, corrosion, etc. are avoided in this way.

Expediently, the closing element has a second bore for exchanging a second damping medium. By means of the second bore, a second damping medium can be transported between two working spaces in the fluid-tight recess during movement of the closing element. The use of a second damping medium, which is independent of the first damping medium, further increases the possibilities for adaptation of the hydraulic vibration damper to desired requirements with respect to the suspension comfort of the motor vehicle. In addition, the second bore in the closing element is also simple and inexpensive to produce.

Advantageously, the second bore is arranged axially in the closing element. In this way, a particularly compact construction of the vibration damper is possible: If a damping of the structure of the motor vehicle by means of the vibration damper, the second bore in the direction of the damping movement, ie formed axially. The storage areas for the second damping medium can thus also be arranged in the axial direction, which allows a smallest possible extent perpendicular to the axial direction of the closing element.

The closing element expediently has two identical first bores. By means of the two first holes, a fluid exchange between the first and second working space of the hydraulic vibration damper both in a compression and a rebound of the wheel in relation to the structure of the motor vehicle, ie a relative movement of the wheel and construction of the motor vehicle, allows.

Advantageously, the vibration damper comprises two valves and at least one valve is designed as a bottom valve. The advantage thus achieved is that a two-pipe damper can be made available so that a part of the damping medium between the working spaces of the hydraulic vibration damper and the compensation chamber can be conveyed by means of the bottom valve and a correspondingly arranged compensation space.

Conveniently, the valve is connected by means of fluid-tight lines to the cylinder. The valve can thus be arranged substantially separately from or outside the cylinder of the vibration damper, which is advantageous overall with regard to the flexibility of the arrangement of the vibration damper on or in the motor vehicle. The cylinder of the vibration damper can then also be made correspondingly compact. At the same time, the valve can be arranged for maintenance purposes in a more favorable manner on the motor vehicle.

Advantageously, the valve has at least one recess for introducing damping medium into the pre-opening, which is formed in particular perpendicular to the axis of the pre-opening. By means of the recess, an improved supply of damping medium in the pre-opening is possible. In addition, the flow rate through the pre-opening and through the closing element can be optimized and / or adapted by means of the formation of the recess. A particularly vertical formation of the recess with respect to the axis of the pre-opening can be made particularly simple and damping medium can occur substantially without friction losses in the recess.

Conveniently, the piston valve comprises an upper and a lower valve, which are designed to block in different directions. Thus, a first and a second working space for the cylinder is provided to a To achieve damping effect by displacement of damping medium between the first and second working space. The blocking in different directions trained valves preferably allow a separate vote of the compression and rebound damping.

Advantageously, the bottom valve has at least two passages which are designed to block in different directions. In this way, the flexibility of the vibration damper is further increased, since by means of the passages of the bottom valve, the flow of damping medium can be set even more flexible and / or adapted to desired conditions.

Other important features and advantages of the invention will become apparent from the dependent claims, from the drawings and from the associated figure description with reference to the drawings.

It is understood that the features mentioned above and those yet to be explained below can be used not only in the particular combination given, but also in other combinations or in isolation, without departing from the scope of the present invention.

Preferred embodiments of the invention are illustrated in the drawings and will be explained in more detail in the following description, wherein like reference numerals refer to the same or similar or functionally identical components or elements.

In each case show in schematic form:

1 a vibration damper in cross-section according to a first embodiment of the present invention;

2 an amplitude-time diagram of spool and piston rod of the vibration damper according to 1 to each other;

3a . 3b Specifications of the vibration damper according to 1 on the motor vehicle;

4a a second embodiment of a vibration damper according to the present invention in cross section;

4b a third embodiment of a vibration damper according to the present invention in cross section;

5 a detailed view of a fourth embodiment of a vibration damper according to the present invention;

6 A fifth embodiment of a vibration damper according to the present invention in cross section.

1 shows a vibration damper in cross section according to a first embodiment of the present invention.

In 1 reference D1 denotes a hydraulic damper. The hydraulic vibration damper D1 comprises a cylinder tube 5 in which a piston rod 6 Is arranged displaceably in the vertical direction. The piston rod 6 has at its end, which in the cylinder tube 5 is arranged, a valve 8a on. At the valve 8a it is a piston valve. The piston valve 8a includes the left and right of the piston rod 6 in each case one passage opening 1' . 7 ' for the passage of damping medium, which in the cylinder tube 5 is located. The upper passage opening 1' is with a spring-loaded valve 1 closed from above; the lower passage opening 7 ' is with a spring-loaded valve 7 Lockable from below. The upper valve 1 is thus designed as a valve of the rebound and the lower valve 7 is designed as a valve of the pressure stage. In the area between the axially spaced positions of the passage openings 1' . 7 ' is in the piston rod 6 a closing element 2 slidably mounted. The closing element 2 has one according to 1 horizontal first hole 2a on, with each side of the closing element 2 arranged pre-openings 3 of the piston valve 8a corresponds. So are the first hole 2a of the closing element 2 and the two pre-openings 3 at the same height, ie their respective axes correspond to each other, become an upper working space 90a and a lower workspace 90b , which are substantially separated by the piston valve, fluidly connected to each other. The closing element 2 is about a spring 4 in the lower area on and in the piston rod 6 spring-mounted.

Now moves the piston rod 6 due to a relative movement between the structure of a motor vehicle and wheel relative to the cylinder 5 , has the closing element 2 in the form of a spool due to its mass and the connection via the spring 4 with a given spring constant to a certain resonance frequency.

Moves the piston rod 6 and thus the piston valve 8th at a frequency below the resonant frequency of the spool 2 , remains the pre-opening 3 essentially open and damping medium can through the pre-openings 3 and the first hole 2a of the spool 2 between the workrooms 90a and 90b be replaced. The damping forces are then correspondingly low.

Swings the piston valve 8a however, with a frequency in the range of the resonance frequency of the spool 2 due to jounce and / or rebound movements of the wheel relative to the structure, a phase shift of 90 ° results between the vibration of the piston rod 6 and the vibration of the spool 2 to that at a maximum speed of the piston valve 8a the spool 2 is in its maximum deflected position. The pre-opening 3 is then through the spool 2 closed and the amount of damping force by the hydraulic damper D1 is essentially through the valves 1 . 7 determined, wherein the damping force is substantially greater than in an excitation with a frequency below the resonance frequency of the spool. The vibration of the piston rod 6 is thus damped and stops quickly. This can increase the driving safety of the motor vehicle as a whole.

For vibrations of the piston valve 8a above the resonant frequency of the spool valve 2 leads the occurring phase shift of 180 ° between the oscillation of the piston rod 6 and the vibration of the spool 2 to one at maximum speed of the piston rod 6 open pre-opening 3 , This can again damping medium on the pre-opening 3 and the first hole 2a of the spool 2 between the two workspaces 90a . 90b be replaced fluidically. The strength of the damping forces is therefore similarly low as in the subcritical excitation case, ie an excitation with a frequency far below the resonance frequency of the control slide 2 ,

This will be in 2 again clarified.

2 shows an amplitude-time diagram of spool and piston rod of the vibration damper according to 1 to each other.

In 2 An XY diagram is shown with a Y-axis 50 , which shows an absolute path amplitude in arbitrary units and with an x-axis 51 that reflects the time. Overall, in 2 four curves 55a . 55b . 55c and 56 shown.

The curve 55a is essentially cosine-shaped and starts with a positive path amplitude of +3.00 at time zero, and then has a zero crossing and a minimum at -3.00, before it again increases to a value of 3.00. The curve 55a thus gives the vibration behavior of the spool 2 in the range of the resonance frequency of the spool valve 2 again.

The curve 55b further shows the vibration behavior of the spool 2 in the supercritical, that is at a vibration of the spool 2 above its resonance frequency. The curve 55b runs with a phase shift of 90 ° on the one hand sinusoidal, on the other hand much flatter than the curve 55b , The maximum amplitude of the spool valve 2 at the bend 55b is only 0.1. In addition, the path amplitude is initially negative.

The curve 55c shows the deflection of the spool valve 2 upon excitation of the spool 2 at a frequency below the resonant frequency of the spool 2 , The spool 2 essentially oscillates in phase with the vibration of the piston rod 56 , Both the curve 55c as well as the curve 56 that the movement of the piston rod 6 in each case runs sinusoidally, wherein the deflection of the spool 2 each smaller than the deflection of the piston rod 6 ,

Furthermore, in 2 in the area of zero passage of the displacement of piston rod 6 and spool 2 when excited below the resonant frequency, a rectangular area 57 located. The area 57 essentially indicates the range in which the relative speed between the cylinder tube and the piston rod is maximum and thus also the damping force that occurs. Next, this is also the area where the pre-opening 3 and the first hole 2a fluidly interconnected to exchange damping medium. This applies to the curves 55c . 55b and 56 , In the area 57 shows the curve 55a their largest deflection, that is, the spool 2 locks the pre-opening 3 completely and it can be between the two workrooms 90a . 90b no damping medium can be exchanged.

3a . 3b show determinations of the vibration damper according to 1 on the motor vehicle.

In 3a is the hydraulic damper D1 according to 1 shown. The piston rod 6 is there with a connection 89a with the unsprung mass of a wheel 9 connected to the motor vehicle. Furthermore, to spring the wheel is a spring 10 arranged, which are at the construction 11 of the motor vehicle is supported. The cylinder 5 of the vibration damper D1 is via another connection 89b with the construction 11 connected to the motor vehicle. In this case, then the resonance frequency of the spool 2 of the hydraulic damper D1, in order to achieve a high driving safety of the motor vehicle, preferably to the natural frequency of the unsprung wheel mass of the wheel 9 Voted.

3b now shows the reverse connection of the vibration damper D1 in the construction of the Motor vehicle. The cylinder 5 is now with the unsprung mass of the wheel 9 connected, whereas the piston rod 6 over a connection 89b with the construction 11 of the motor vehicle is firmly connected. It is advantageous, a resonance frequency of the spool 2 to tune or set to a natural frequency of the structure of the motor vehicle. In this way, an improvement of the vibration comfort of the motor vehicle can be achieved.

4a shows a second embodiment of a vibration damper according to the present invention in cross section.

In 4a a twin-tube damper D2 is shown. The piston rod 6 protrudes from the top into the cylinder 5 of the twin-tube damper D2. At the bottom of the piston rod 6 is the first piston valve 8a arranged. A second piston valve 8b is designed as a bottom valve and fixed to the inner wall of the cylinder 5 connected. The two piston valves 8a . 8b have essentially the same structure according to the piston valve 8a of the 1 on. Furthermore, in contrast to the monotube D1 is the cylinder tube 5 now in three work areas, comprising a first work area 90a (Area above the first piston valve 8a ), a second workspace 90b (Area of the cylinder tube 5 between the two piston valves 8a and 8b ) and a third workspace 90c below the piston valve 8b , divided up. The lower workspace 90c is over a line 13 with a surge tank 12 fluidly connected for damping medium. In this way, a targeted damping of a wheel and / or a body build frequency is possible.

4b shows a third embodiment of a vibration damper according to the present invention in cross section.

4b also shows a twin-tube damper D2. Instead of the piston valve 8a of the twin-tube damper D2 the 4a is just a piston with a check valve 1a on the piston rod 6 arranged. Instead of the bottom valve 8b of the twin-tube damper D2 according to 4a At the bottom are two valves 1b and 7a arranged. The valve 1b is as a check valve, whereas the valve 7a is designed as a valve of the pressure stage. The valve of the pressure stage 7a is arranged spring-loaded. The valves 1b and 7a close thereby parallel to the extension direction of the piston rod 6 arranged passages 21a . 21b , so that a passage of damping medium between the third working space 90c and the second workspace 90b is prevented when both valves 1b . 7a are closed.

Analogous to 4a Thus, in the two-pipe damper D2 a subdivision into three working spaces 90a . 90b and 90c reached. The workroom 90c is again via a line 13 with a surge tank 12 connected for damping medium. In contrast to 4a is now a piston valve 8a arranged in a separate container. The side of the rebound of the piston valve 8a is over a line 13 with the workspace 90a fluidly connected, the side of the pressure stage is on the other hand via a line 13 with the workspace 90c fluidly connected. The piston valve 8a lies outside the cylinder 5 in a separate and fluid-tight container.

5 shows a detailed view of a fourth embodiment of a vibration damper according to the present invention.

In 5 is a piston valve 8a which essentially shows the structure of the piston valve 8a of the 1 equivalent. In contrast to 1 are the passage openings 1' . 7 ' at substantially the same axial height of the piston rod 6 left and right of this and parallel to the axis of the piston rod 6 arranged. On the respective inside towards the piston rod 6 are recesses 16a and 16b in the piston valve 8a arranged, which arranged on both sides of the piston rod pre-openings 3 of the piston valve 8a correspond. The recesses 16a . 16b are designed annular groove in cross section. Between the two pre-openings 3 is inside the piston rod 6 a spool 2 arranged, one to the pre-openings 3 corresponding horizontal circumferential groove 2a having. In this way, damping medium can over the recess 16a enter and about the pre-opening 3 in the circumferential groove 2a and continue over the second pre-opening 3 in the recess 16b enter and so the two work spaces 90a . 90b fluidly interconnect. In cross-section thus results essentially an S-shaped flow path for the damping medium.

The spool 2 is over a lower spring 4b and an upper spring 4a in a fluid-tight recess 20 the piston rod 6 arranged resiliently on both sides. Furthermore, the spool 2 an axial bore 15 , ie parallel to the extension direction of the piston rod 6 , on, the spaces above and below the spool 2 in the fluid-tight recess 20 fluidly interconnected. In these rooms, a second damping medium can be introduced, which is the movement of the spool 2 in the axial direction by means of the flow resistance of the bore 15 attenuates. The two springs 4a . 4b are designed as centering springs and formed swinging in the longitudinal direction of the vibration damper. Overall, by means of the size of the Flow resistance of the bore 15 and / or the stiffness of the springs 4a . 4b the vibration behavior of the spool valve 2 be influenced by the frequency. The valves 1 . 7 the rebound or compression are in 5 also indicated.

6 shows a fifth embodiment of a vibration damper according to the present invention in cross section.

In 6 is essentially a vibration damper D1 according to 1 shown. In contrast to 1 points the spool 2 two axial and spaced apart first holes 2a and 2 B on. The mechanism of the damper D1 of the 1 is in 6 vice versa. An attenuation is then not amplified when an occurrence of a certain frequency, but attenuated. At excitation frequencies far below or far above the resonant frequency of the spool 2 is the pre-opening 3 usually through the spool valve 2 locked. In the case of resonance, that is with vibration of the control slide 2 with its resonance frequency, this becomes in the range of maximum speed of the piston rod 6a opened, allowing a particularly soft damping.

In summary, the invention has, inter alia, the advantage that a more targeted damping with regard to driving safety or driving comfort of critical frequencies between the wheel and the construction of the motor vehicle is made possible. In addition, the vibration damper is simple in construction, so that can be dispensed with an expensive and complicated electronic control by appropriate means. Likewise, an optimum of driving comfort and driving safety is provided by the vibration damper.

Although the present invention has been described above with reference to preferred embodiments, it is not limited thereto, but modifiable in many ways.

LIST OF REFERENCE NUMBERS

D1

monotube

D2

Twin-tube dampers

1

Valve rebound

1a

Valve rebound

1b

Valve rebound

1'

Port

2

spool

2a

Bore spool

3

pre-opening

4

centering

4a

upper centering spring

4b

lower centering spring

5

container tube

6

piston rod

6a

piston

7

Valve pressure stage

7a

Valve pressure stage

7 '

Port

8a

piston valve

8b

piston valve

9

wheel

10

feather

11

Construction vehicle

12

surge tank

13

management

15

axial bore

16a

recess

16b

recess

20

fluid-tight recess

21a

passage

21b

passage

50

displacement amplitude

51

Time

55a

Curve spool resonance

55b

Curve spool above resonance

55c

Curve spool below resonance

56

Curve piston rod

57

Area

89a

connection

89b

connection

90a

first working space

90b

second workspace

90c

third workspace

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• DE 2758083 A1 [0005]

Claims (13)

Hydraulic vibration damper (D1, D2), in particular for motor vehicles, comprising a cylinder ( 5 ), in which a piston rod ( 6 ) is slidably disposed with a piston, and a valve ( 8th ), in particular a piston valve, wherein the valve ( 8a . 8b ) at least one passage opening ( 1' . 7 ' ) and at least one pre-opening ( 3 ) for exchanging damping medium between a first working space ( 90a ) and a second working space and wherein the pre-opening ( 3 ) by means of a closing element ( 2 ) is closable, characterized in that the closing element ( 2 ) at least a first bore ( 2a ), which with the pre-opening ( 3 ) and that the closing element ( 2 ) inside the valve ( 8a . 8b ) is slidably disposed. Vibration damper (D1, D2) according to claim 1, characterized in that the closing element ( 2 ) in the valve ( 8a . 8b ), in particular two-sided, resilient ( 4 . 4a . 4b ) is stored. Vibration damper (D1, D2) according to at least one of claims 1-2, characterized in that the closing element ( 2 ) in the valve ( 8a . 8b ) in a fluid-tight recess ( 20 ) is arranged. Vibration damper according to at least one of claims 1-3, characterized in that the closing element ( 2 ) a second bore ( 15 ) for exchanging a second damping medium. Vibration damper according to claim 4, characterized in that the second bore ( 15 ) axially in the closing element ( 2 ) is arranged. Vibration damper according to at least one of claims 1-5, characterized in that the closing element ( 2 ) two equal first holes ( 2a . 2 B ) having. Vibration damper according to at least one of claims 1-6, characterized in that two valves ( 8a . 8b ) are arranged, and at least one valve ( 8b ) is designed as a bottom valve. Vibration damper according to at least one of claims 1-7, characterized in that the valve ( 8a . 8b ) by means of fluid-tight lines with the cylinder ( 5 ) connected is. Vibration damper according to at least one of claims 1-8, characterized in that the valve ( 8a . 8b ) at least one recess for introducing damping medium in the pre-opening ( 3 ), which in particular perpendicular to the axis of the pre-opening ( 3 ) is trained. Vibration damper according to at least one of claims 1-9, characterized in that the valve ( 8a . 8b ) an upper and a lower valve ( 1 . 7 ), which are designed to block in different directions, Vibration damper according to claim 7, characterized in that the bottom valve ( 8b ) at least two passages ( 21a . 21b ), which are formed locking in different directions. Motor vehicle with a vibration damper (D1, D2) according to at least one of claims 1-11. Use of a vibration damper (D1, D2) for frequency-dependent damping of vibrations in household appliances, in particular washing machines, and / or in land, air or water vehicles, especially in motor vehicles.

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