DE3312899C2 - Adjustable valve for the piston rod of a vibration damper - Google Patents

Abstract

The invention relates to a controllable shock absorber, in particular for motor vehicles, consisting of a cylinder with a damping medium and a piston rod which carries a piston at its end. The piston rod has a longitudinal bore and a transverse bore passing through it, which can be closed by an electrically controlled control slide which is movable by means of an electrical coil arranged on the piston rod. The control slide is a rotary slide that has a radial bore in its wall which more or less exposes the transverse bore, the rotary slide being designed as a rotor of a stepper motor, the stator of which consists of a plurality of magnets with excitation coils and which are arranged around the piston rod are. Furthermore, an electronic control circuit is arranged within the cylinder, which supplies the electrical switching pulses to the stepping motor as a function of the entered data for the step-by-step rotation of the rotary valve.

Description

a) the rotary slide of the valve is a sleeve (26) which coaxially connects the piston rod (3) in the area of the Radial channels (25) encloses and the wall according to the number of radial channels has radial openings (31, 32) which when the sleeve is rotated relative to the piston rod release the radial channels more or less,

b) the electromagnets (20, 22; 21, 23; 40; 41; 42; 43; 44; 45) are coaxial within the cylinder (2) arranged around the piston rod (3) and form the stator of a stepper motor, wherein the sleeve (26) forms the rotor of the stepping motor,

c) an electronic regulating and control circuit (46) is arranged within the cylinder (2), which sends the electrical switching impulses to the stepper motor depending on the specified Data such as B. temperature or viscosity of the damping medium (s), path of the shock absorber (1), speed and acceleration of the vehicle, supplies to the appropriate stepwise rotation of the sleeve (26).

2. Adjustable valve according to claim 1, characterized in that the electromagnets (20, 22; 21, 23; 40; 41; 42; 43; 44; 45) of the stator of the stepping motor are each rod-shaped and at their upper ends on the piston rod (3) and are arranged around the same parallel to this and that the sleeve carries magnetizable cams (27,28,34,35,36,37,38,49,50,53) along its circumference and is designed as an internal rotor of the stepping motor, the electromagnets pushing the sleeve into the area protrude beyond the cam and are designed as pole shoes (29) in this area.

3. Adjustable valve according to claim 1 or 2, characterized in that the electronic control and control circuit (46) is arranged within a bore (51) of the piston rod (3).

4. Adjustable valve according to claim 2, characterized in that the magnetizable cams (27, 28, 34, 35, 36, 37, 38, 49, 50, 53) of the sleeve (26) are part of a magnetizable disc (33) which on the sleeve is placed centrally.

5. Adjustable valve according to claim 2, characterized in that the sleeve consists of plastic and at its upper end has a ring made of magnetizable material, which the cams wearing.

6. Adjustable valve according to claim 1, characterized in that the sleeve (26) is a torsion spring (30) for resetting in a defined zero position.

7. Adjustable valve according to claim 1, characterized in that for measuring the acceleration an acceleration sensor (54) is arranged in the cylinder (2)

8. Adjustable valve according to one of the preceding claims, characterized in that the rotary slide valve of the stepper motor is designed as an external rotor and the electromagnets of the internal Encompasses stator

9. Adjustable valve according to claims 2 or 3, characterized in that the on the sleeve (26) located number of cams (27,28,34,35,36,37, 38,47,48,49) the number or double the number corresponds to the steps to be carried out on the rotary valve

10. Adjustable valve according to one of the preceding claims, characterized in that the piston rod (3) inside in the area of the radial channels (25) a valve disk (57) for closing the radial channels having in a preferred direction.

U. Adjustable valve according to claim 10, characterized in that the valve disk {27) within a blind bore (56) arranged above the opening of the longitudinal bore (24) in the radial channels (25) is, wherein the valve plate is optionally spring-loaded.

The invention is based on a controllable valve for the piston rod of a vibration damper according to FIG the preamble of claim 1.

From DE-OS 32 41 984 a hydraulic damper is known which has a cylinder and comprises a piston operating in the cylinder which divides the interior of the cylinder into two fluid chambers. A damping force generating valve is attached to the piston to generate the damping force in both stroke directions of the damper attached, as well as a KoI -benstange in which a coaxial bore and a radial channel are formed which form a bypass passage for connecting the two liquid chambers. A The rotatably adjustable valve element gradually controls the effective area of the bypass passage. An operating rod is attached to the valve member and runs through the coaxial bore of the piston rod. An operating mechanism for the valve member comprises a support member which is attached to the piston rod and carries at least two electromagnets outside the cylinder. A magnetizable part is with the operating rod connected, wherein an electrical circuit is used to selectively energize the electromagnets, the attract the magnetizable part and thereby rotate it. With such a device, the damping force property this hydraulic damper can be adjusted from outside the same.

This hydraulic damper has the disadvantage that it is suitable for use in a regulated system is not suitable for the current road conditions. Due to the arrangement of the electromagnets outside of the cylinder and the necessary operating rod into the interior of the cylinder this valve has a large inertia that

it to react quickly according to the vibration changes due to changes in road conditions make unsuitable.

A further disadvantage is that the rotary valve as Wedge ring is formed, which at the high pressures used today within vibration dampers can certainly lead to leakage.

The invention is therefore based on the object of a controllable valve for the piston rod of a To create vibration damper, which is practically inertial to changes in external conditions, for example the road holding, reacts optimally, with no falsification of the position of the rotary valve should occur so that the valve reacts practically without delay to any momentary changes, such as road conditions, adapts.

This object is achieved according to the invention by claim 1. Further developments of the invention are characterized in the subclaims.

With the adjustable valve according to the invention the advantages achieved that such a vibration damper practically without time delay automatically adjusting to any given road situation. The rotary slide of the valve has only one very low inertia, which is why the sleeve is practically inert to the alternating excitation of the electromagnets can react. Furthermore, a high level of tightness of the is due to the structure according to the invention Valve and thus controlled throttling of the cross-section of the passage. In an advantageous manner act on the rotary valve due to the symmetrical arrangement of the radial channels within the piston rod no asymmetrical radial forces, which additionally supports the easy mobility of the rotary valve. Furthermore, all necessary assemblies of the valve are advantageously within the Integrated cylinder of the vibration damper, also a possibly existing acceleration sensor and a device for measuring the path of the wheel in relation to the body. In addition, the Regulating and control circuit a number of limit values are stored, which the vibration damper at Influence the presence of the same in a desired manner.

The vibration damper according to the invention can thus be used to meet all requirements of changing road conditions react optimally. For example, the vibration damper must be used when braking and accelerating get hard. Likewise de must; Vibration damper when rocking the vibrations of the Damping the body so that the vibration damper starts at a certain distance of the body that is being measured also dampen these vibrations. This means that the vibration damper is only slightly Travel area should vibrate softly.

Furthermore, the vibration damper according to the invention makes it possible that now each wheel for itself can be controlled in terms of vibration alone and thus each vibration damper is independent of can optimally adapt automatically to the other current road conditions. Likewise, there is no adulteration the position of the rotary valve due to strong vertical accelerations possible because of the Rotary valve does not perform any longitudinal movements, but only rotary movements.

Regarding the design of the controllable valve as a stepping motor, it should be said that stepping motors are known as such.

Two examples of the invention are shown in the drawing and described below. It shows

F i g. 1 shows a cross section through a vibration damper to represent the cylinder, the piston rod and the valve, consisting of aas rotary valve and Passage,

F i g. 2 shows a plan view of the cross section along the section line AA in FIG. 1, where the excitation coils of the magnets have been omitted and

ίο Fig.3 a section through a piston rod of a Another vibration damper, the inside in the area of the radial ducts a valve to close the same having in a preferred direction.

In the figures, the same parts are provided with the same reference numbers.

According to FIG. 1, the vibration damper 1 consists of a cylinder 2 which is closed at both ends. Of the Cylinder 2 is filled with at least one damping medium, this being a liquid and / or a gas can be. The upper end of the cylinder is closed by means of a cylinder cover 16. Through the cylinder cover 16, a piston rod 3 protrudes into the cylinder 2, the passage by means of an annular seal 17 is sealed to the piston rod. At the top of the piston rod and at the bottom of the cylinder is in each case a holder 4, 5 for fastening the vibration damper 1 on the one hand to the body and on the other hand arranged on the wheel or on the axle of the vehicle. The piston rod is preferably hollow and has a longitudinal bore 51 into which an end piece 52 is screwed at the lower end. The piston rod 3 has a piston 8 at its end 15 on the cylinder side. This piston is by means of a nut 14, which is screwed onto the lower end of the piston rod 15, firmly connected to the piston rod.

The piston 8 can be an ordinary piston, as it is known in vibration damper construction, which is why the Piston 8 has through bores 9, 10 which are covered by means of spring assemblies 11, 12. The feathers can e.g. B. have different spring values, whereby the piston 8 has a high pressure and a low pressure valve represents. The piston 8 divides the cylinder interior into a lower chamber half 6 and one upper chamber half 7, which is thus in the in F i g. 1 embodiment shown via the through holes 9, i0 are related to each other.

The piston rod 3 has an end piece 52 which is screwed into the piston rod 3 and on which the piston 8 is attached. The lower end 15 of the piston rod 3 or of the end piece 52 points outwards from the end face of the end piece 52, a longitudinal bore 24 which is central to the longitudinal axis of the piston rod 3 and extends beyond the piston 8. The end piece faces transversely to this longitudinal bore 24 52 or the piston rod 3 above the piston 8 has radial channels 25 which radially form the longitudinal bore 22 enforce, the number of these radial channels 25 may be even or odd. In the F i g. 1 and 2 two radial channels are identified, which form a through hole 25 along a diameter. To the Increasing the flow through the radial channels or the bores can be a plurality of the same in radial Arrangement. The bores 24, 25 thus connect the chamber halves 6 and 7 with one another and form a bypass.

The piston rod 3 has eight magnets 20, 21, 40, 41, 42, 43, 44, 45 in the area of the upper chamber half on, which is arranged in a ring around the piston rod

and are firmly connected to it. These magnets are preferably rod-shaped and extend parallel to the longitudinal axis of the piston rod. The magnets each have an excitation coil 22, 23 for generation a magnetic flux within the respectively controlled magnets.

The magnets 20, 21, 40, 41, 42, 43, 44, 45 are as in FIG F i g. 2, arranged at equidistant intervals on a disk 19 which has a central bore, through which the piston rod 3 is guided. For this purpose, it has a circumferential shoulder 18 with a thread in the End area, the disk 19 being screwed onto the piston rod 3. In this way they are Magnets firmly connected to the piston rod 3.

On the piston S is coaxial around the piston rod 3 arranged around in the area of the transverse bore 25 a rotary slide valve 26, which is sleeve-shaped and which also has two through bores 31, 32 (Figure 2), which with the transverse bore 25 at certain Position of the rotary valve are in cover. To hold the rotary valve 26, the piston rod or the end piece 52 on a further circumferential shoulder 48 at the height of the rotary valve. That The upper end of the rotary valve 26 has a certain number of cams 27,28,34,35,36,37,38,49,50,53 or teeth that face the pole pieces 47 of the magnets laterally. The lower ends of the magnets thus protrude or overlap the cams of the rotary valve. Thus, the magnets together with the form on it seated excitation coils an external stator 39, the rotary valve with the cams an internal Rotor of a stepper motor, the cams in turn representing the pole pieces of the rotor. For example is shown in FIG. 1 the magnetic circuit closed via the magnet 20, the cam 27 of the rotary valve 26, the cam 28 of the rotary valve, the reversely excited magnet 29 and the retaining disc 19, the made of magnetizable !! Material consists. The cams of the rotary valve, preferably in pairs opposing cams are magnetically short-circuited with one another. The magnets consist of known magnetic materials of high permeability.

FIG. 2 shows a section along the line AA in FIG. 1, the stepper drive being made up of eight magnets, which are arranged at equidistant intervals around the piston rod 2. The rotary valve 26 is designed for four steps. Preferably, the opposing magnets are magnetically excited in opposite directions, so that the magnetic circuit is closed via the opposing magnets in pairs.

In FIG. 2, for example, at step zero, the opposing cams 34, 38 the pole pieces of the magnets, which are also oppositely situated in pairs 40.43 opposite. The next cam 35 on the disk is one step in front of the magnet 41. At Step one is, for example, the magnet 41 and magnetically opposite to that opposite Magnet 45 energized. As a result, the cam 35 and the opposing cam 49 moves into the immediate Area of the pole shoes of the magnets 41, 45, with the next following cam 36 one step before The next following magnet 42 is available In step two, the magnet 42 and the opposite one are now 44 excited so that the cam 36 and the opposite 50 directly opposite the pole pieces of Magnets 42,44 come to rest. The next following cam 37 is now one step before the next Magnet 21. In step three, magnet 21 and the opposing magnet 20 are now excited, so that the cam 37 directly opposite the pole piece of the magnet 21 and the opposite Cam 53 are also moved relative to the magnet 20. In this way, when driving the magnets always move through the row of magnets ascending and descending by the control circuit.

Furthermore, if required, an acceleration sensor 54 can be arranged in the interior of the cylinder, which is preferably arranged in the chamber half in which the control circuit 46 is also located.

! 5 With the vibration damper according to the invention it is not necessary - but possible - from outside the same control variables, such as the speed, the Acceleration or speed to be fed to the control circuit. Entering the route is sufficient. which can preferably also be obtained within the vibration damper. Because crucial is just the quick change of the stepper motor. If this responds before that with a vibration damper for motor vehicles occurring maximum vibrations of approx. 10 to 12 Hz become effective, you can access the input or processing of a speed, acceleration or speed signal and only process a path-dependent signal as a control signal, which is the relative movement of the piston to the cylinder - wheel to the body - is proportional. In this In this case, there is a real self-regulating vibration damper, which only needs the supply voltage from the outside must be supplied. Therefore, in a motor vehicle, all four vibration dampers can be independent regulate each other automatically.

An acceleration sensor is only necessary at higher frequencies, for example only from approx. 100 Hz, So if the vibration damper according to the invention is not for motor vehicles, but for vibration damping is used on rapidly vibrating machines or units.

This means that each vibration damper can provide the optimal damping in each case, independently of one another the requirements, for example road conditions, and calculate the rotary valve accordingly to adjust. With the exception of the power supply, all parts are integrated in the vibration damper itself.

The use of the conventional piston 8 with high and low pressure ver.ti! is therefore advantageous because in the event of a failure of the automatic control, the damping function of the vibration damper is fully retained for its limit values

The control circuit has a microcomputer and / or a microprocessor, which all control signals, Speed, acceleration, engine speed and travel of the vibration damper are processed and accordingly controls the magnets of the stator, whereby the rotary valve for the respective momentary Situation is optimally adjusted.

The torsion spring 30 is used in the event of a failure of the automatic electrical control Rotate the rotary valve into its closed position, so that the connection of the two chamber halves via the Longitudinal bore 24 and the transverse bore 25 is closed and now the valves within the piston 8 in Step activity, with which the vibration damper his

full functionality, but designed for limit values, retains.

3 shows another embodiment of a controllable valve according to FIG. 1, of which only the end piece of the piston rod is shown.

On the piston rod 3, an end piece 55 is arranged, preferably screwed in, which has a central Has blind hole 56. A valve 57 is arranged within this blind bore, in the end part of the Blind bore 56, a compression spring 58 can also be arranged, which the valve 57 in a preferred direction moved to close the mouth of the longitudinal bore within the lower end 15 of the piston rod.

The valve 57 is open when the damping curve is positive, that is, when the flow against the valve controller 57 is from below. If the vibration damper swings out, the damping medium wants to move from chamber 7 to Chamber 6 via the openings 3i, 32 of the rotary valve 26, the bore 25 and the longitudinal bore 24 of the piston flow back when the rotary valve 26 is fully open, so the valve 57 is moved downwards by the flowing medium and / or the compression spring 58 and abruptly closes the mouth of the longitudinal bore 24. The rotary valve is in its full controlled open position. The decay process can now via the valves 9 and 10 within the Piston 8 (Fig. 1) take place. Now hits during the decay process, i.e. with a negative damping curve, before the decay process reaches its zero line has reached an event, for example, the wheel is suddenly moved towards the body, so that the If the damping curve becomes positive again, the rotary valve is activated immediately according to the calculated value adjusted. Since the valve 57 is lifted from the damping medium, the bypass is permeable again and it a new transient process can be added to the previous, not yet completed transient process connect.

List of reference symbols

45

50

55

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1 Vibration damper 2 cylinder 3 Piston rod 4.5 Brackets 6th Lower half of the chamber 7th Upper half of the chamber 8th Pistons 9.10 Valve bores 11.12 Valve springs 13th Ring seal 14th mother 15th Lower end of the piston rod 16 Cylinder cover 17th Ring seal 18th shoulder 19th disc 20.21 Magnets 22.23 Excitation coils 24 Longitudinal bore 25th Cross hole 26th Rotary valve 27.28 cam 29 Lower end of the magnets 30th Torsion spring 31.32 Hole within the Rotary valve

33 disc 34,35,36,37 38,49,50,53 cam 39 stator 40,41,42, 43,44,45 Magnets 47 Pole piece 48 Paragraph _m 46 Control circuit 51 drilling 52 End piece 54 Accelerometer 55 End piece 56 Blind hole 57 Valve 58 Compression spring 59 Connections of the excitation coils

For this purpose 2 sheets of drawings

Claims (1)

Patent claims: 1. Adjustable valve for the piston rod of a vibration damper, a cylinder and the Includes piston rod with piston, which divides the volume of the cylinder into two chambers, the Piston rod in the area of the piston has a longitudinal bore and above it the longitudinal bore having penetrating radial channels, which together have a passage to connect the two chambers form, which can be closed in stages by a rotary valve that is operated by means of electromagnets and an electrical circuit for selectively energizing one of the electromagnets rotatably on the Piston rod is arranged, characterized by the following features: