DE3312899A1 - Self-controlling shock absorber, in particular for motor vehicles - Google Patents

Abstract

The invention relates to a controllable shock absorber, in particular for motor vehicles, consisting of a cylinder with damping medium and piston rod which bears a piston at its end. The piston rod has a longitudinal bore and a transverse bore which penetrates the latter and can be closed off by means of an electrically controlled control slide which can be moved by means of an electrical coil arranged on the piston rod. The control slide is a rotary slide valve which in its wall has a radial bore which clears the transverse bore to a greater or lesser extent, the rotary slide valve being constructed as a rotor of a step motor whose stator is composed of a multiplicity of magnets with excitation coils and which are arranged around the piston rod. Furthermore, an electronic control circuit is arranged inside the cylinder, which circuit supplies the electrical switching pulses to the step motor as a function of the input data for the purpose of incrementally rotating the rotary slide valve. <IMAGE>

Description

Description; Self-regulating shock absorbers, in particular

for automobiles The invention relates to a self-regulating one Shock absorbers, in particular for motor vehicles, consisting of a closed at both ends Cylinder filled with at least one damping medium and with a piston rod, which is sealed into the cylinder and the one at its end on the cylinder side a piston sealed against the cylinder wall - possibly with a direction-dependent piston High and low pressure valves, which support the cylinder space in two chamber halves divides, the piston rod for -possibly additional- connection of the two chamber halves a longitudinal bore in the area of the piston and above it has at least two radial openings penetrating the longitudinal bore, which can be closed by an electrically controlled control slide, which is operated by means of on the piston rod arranged electrical coils is movable.

A variety of shock absorbers have become known, including Infinitely adjustable or controllable shock absorbers are already known. The DE-OS 15 05 497 includes e.g. B. a continuously adjustable shock absorber, in particular for motor vehicles, consisting of a cylinder filled with damping fluid, a hollow piston rod arranged displaceably therein with therein housed control means and a working piston with two arranged in it Groups of axially extending liquid passage channels is provided by which each group on the outlet side through preferably on its inner circumference firmly on Piston clamped valve spring plates is covered, at least one valve plate.

package by one on its outer circumference with by the control means adjustable contact pressure applied support piston is supported. That the hollow piston rod enforcing control means acts directly on the support piston, the contact pressure of the support piston regardless of the hydraulic conditions prevailing in the damper can be regulated. The design used here to regulate the shock absorber however, it is not very effective. Because there is still a superposition of the Attenuation influences a, whereby an accurate and flawless stepless Attenuation setting is not possible.

In another known adjustable shock absorber of this type according to the German patent application B 81 235 II / 63 c and B 82 476 II / 63 c takes place Regulation of the support piston or pistons resting against the valve spring plate assemblies for the purpose of End of the damper setting via a hollow piston rod arranged adjusting rod through which throttle openings leading to the support piston more or less wide open and by the hydraulic that is set in the process Flow pressure or dynamic pressure on the support piston with regard to their contact pressure the valve spring plate can be regulated. The support piston is regulated here thus depending on the hydraulic conditions prevailing in the damper. Such a control of the damping resistance also leads to superimpositions the damping effects. The attenuation caused by the different placement of the am Working piston clamped valve spring plates is caused, the superimposed contact pressure of the support piston or pistons depending on the respective dynamic pressure conditions. This results in greater inaccuracies for today's motor vehicle construction are no longer tolerable. Furthermore, the use of the support piston is disadvantageous.

DE-OS 16 55 647 is also a controllable hydraulic Telescopic shock absorbers, especially for motor vehicles, have become known with a control element located outside the damping body via a transverse and / or an axial bore in a piston rod is in communication. Within a control room, through a cylindrical widening of the axial bore at the end of the piston rod is formed, a control sleeve and a control piston between the spring element ments and a stop arranged. This arrangement works like those previously mentioned, purely hydraulic. To control or regulate the shock absorber must therefore from the outside disadvantageously, an additional hydraulic medium can be supplied. Therefore additional units must be made available externally, e.g. B. to generate pressure, which makes an additional effort that is no longer justifiable today.

Furthermore, DE-OS 24 41172 is a wheel suspension for land vehicles become known, with a hydraulic between the carrier and the body Damping device, a displacement converter and an acceleration converter the vehicle body are arranged. The displacement transducer produces a first Signal corresponding to the position of the wheel carrier opposite the body, the The acceleration converter on the vehicle body generates a second signal, which corresponds to the vertical component of the acceleration of the body at the wheel. There is also a control device which is used to change the damping force the damping device in function according to the first and the second signal can be set so that the second signal from the acceleration converter has a setpoint value is caused to take as a function of the first signal. To this end, the control device a function generator to which the first signal is fed at an output terminal and which generates an output signal that corresponds to a setpoint value of the second signal corresponds, with a comparator being provided which corresponds to the damping device the error between the second signal and the output signal from the function generator controls.

The disadvantage of this hydraulic damping device is that the two signals from different attenuators norms must be and the control signal, in turn, two different damping devices is also supplied by DE-PS 29 11 768 a controllable shock absorber, has become known in particular for motor vehicles, which consists of a damping fluid filled cylinder and with a cylindrical pot overlapping the cylinder consists, which has a piston rod centrally and axially inside, which is inserted into the cylinder immersed and the disc sealed against the cylinder wall at its end carries, which divides the cylinder space into two chamber halves and the direction-dependent Has high and low pressure valves with one in an axial bore of the piston rod movably arranged, in the axial direction spring-loaded control slide, the in the rest position / working position an additional passage opening between the closes both halves of the chamber. The control slide is in the axial direction arranged on an armature that is immersed in an electrical coil that is inside the longitudinal bore is arranged in the upper part of the piston rod; and the one electric Having feed line from outside the shock absorber.

Furthermore, the cylinder has at least one at its upper end Permanent magnets, on the cylindrical inner wall of the pot in the axial Direction at least one coil is arranged, which also has a feed line from outside the shock absorber.

Furthermore, in the German patent application P 32 27 903.5 a Adjustable shock absorber has been proposed that is similar to the adjustable shock absorber the DE-PS 29 11 768 is built. Here, too, the control slide is in the axial direction spring-loaded, with an additional through opening in the rest or working position (Bypass) between the two chamber halves is closed or opened.

The spring for moving the control slide is here a bimetallic spring for the axial temperature-dependent position of the control slide within the flow path of the bypass.

The problem with the latter two shock absorbers is the as Piston rod made in tube. Special static conditions must be observed here which is of course possible through the choice of material. However, this will the production of the shock absorber becomes more expensive.

The invention is therefore based on the object of a self-regulating To create shock absorbers of the type mentioned, which are practically instantaneous automatically adapts to all current road conditions, with the shock absorber its damping characteristics automatically according to the given road conditions should change.

The solution to this problem is the combination of the following features: a) the control slide is a sleeve-shaped rotary slide valve (26) which coaxially supports the Piston rod (3) in the area of the openings (25) and in its wall corresponding to the number of openings has radial openings (31, 32) which when turning the rotary valve raltiv to the piston rod the breakthroughs more or release less, b) the rotary valve is designed as a rotor of a stepper motor, whose stator consists of a plurality of magnets, each with an excitation coil and which also surround the piston rod coaxially, c) within the cylinder an electronic control circuit that can be controlled from outside is arranged, which sends the electrical switching pulses to the stepper motor depending on the entered Data such asRz.Bv temperature or viscosity of the Dåmpfunn.smedi-en, route of the Shock absorber, speed and acceleration of the vehicle, provides for gradual Rotation of the rotary valve.

The shock absorber according to the invention has the salient advantage that this self-regulating itself practically without any time delay Road holding adjusts. In a highly advantageous manner, all are necessary for this Aggregates integrated within the cylinder of the shock absorber, including an existing one Accelerometer and a device for measuring the path of the wheel over it In addition, a number of limit values can be stored in the control circuit, which influence the shock absorber in the desired manner when the same is present.

This enables the shock absorber to react correctly to all requirements.

For example, the shock absorber must be used when braking and accelerating get hard The shock absorber also has to cope with the vibrations of the body when rocking dampen, so that the shock absorbers from a certain path of the body that is being measured also dampen this vibration. That means that the shock absorber is only in one should vibrate softly in the small travel range.

Furthermore, the shock absorber of the invention enables that now each wheel is controlled by itself and each shock absorber is independent of the rest of the current road conditions automatically adapts.

In the shock absorber according to the invention, the rotary valve is practical no inertia, which is why it reacts to the control signals of the electric magnet reacts. In addition, there is no falsification of the position of the rotary valve due to strong accelerations, since the rotary valve does not perform any longitudinal movement. They also act on the rotary valve at the same time Control of two pairs of opposing electric magnets no radial forces.

*) opposite the body.

In an advantageous embodiment of the invention, the rotary slide valve preferably designed as an internal rotor of the stepper motor, but the rotary valve can also be designed as an external rotor.

Further advantageous refinements of the invention are set out in the subclaims marked.

Examples of the invention are shown in the drawing and subsequently described. The figures show: FIG. 1 a cross section through an entire shock absorber to show the cylinder, the piston rod, the rotary valve and the magnets, Fig. 2 is a plan view of the cross section along the section line A-A in Fig. 1, wherein the excitation coils of the magnets have been omitted and FIG. 3 shows a section by another piston rod, the inside in the area of the openings a valve for closing the breakthroughs in a preferred direction.

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

According to FIG. 1, the regulatable shock absorber 1 consists of a cylinder 2, which is closed at both ends. The cylinder 2 is provided with at least one damping medium filled, whereby this one liquid bath can be a gas. The top of the Cylinder is closed by means of a cylinder cover 16, which is in the Cylinder 2 can be screwed in. A piston rod protrudes through the cylinder cover 16 3 into the cylinder 2, the passage by means of an annular seal 17 for Piston rod is sealed. At the top of the piston rod and at the bottom of the cylinder is a holder 4, 5 for fastening the shock absorber 1 on the one hand on the body and on the other hand on the wheel or axle of the vehicle arranged. 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 at its end 15 on the cylinder side 8, which is normally disc-shaped. This piston is means of a nut 14 screwed onto the lower end of the piston rod 15, firmly connected to the piston rod.

The piston 8 can be an ordinary piston, such as is used in shock absorber construction is known, which is why the piston 8 has through bores 9, 10, which means Spring assemblies 11, 12 are covered. For example, the springs can have different spring values aufweizsen, whereby the piston 8 represents a high pressure and a low pressure valve. The piston 8 divides the cylinder interior into a lower chamber half 6 and one upper chamber half 7, which is thus in the embodiment shown in Figure 1 on the Through bores 9, 10 are in communication with one another.

The piston rod 3 can have an end piece 52 which is inserted into the The piston rod 3 is screwed in and on which the piston 8 is placed. That has lower end 15 of the piston rod 3 or of the end piece 52, starting from the End face of the end piece 52, a longitudinal bore 24 which is central to the longitudinal axis the piston rod 3 runs and extends beyond the piston 8. Across from this The end piece 52 or the piston rod 3 has the longitudinal bore 24 above the piston 8 openings that penetrate the longitudinal bore 22 radially, the number these breakthroughs can be even or odd. In Figures 1 and 2 there are two Breakthroughs marked, here a through hole 25 along a diameter form. According to the desired characteristics, the openings can be slit-like or be conical.

To increase the flow through the openings or holes a plurality of these may be present in a radial arrangement. Connect with it the bores 24, 25, the chamber halves 6 and 7 together and create so in the preferred use of the piston 8 with high and low pressure valves a bypass.

The piston rod 3 now points in the area of the upper chamber half 7 Magnets 20, 21, 40, 41, 42, 43, 44, 45, which are arranged in a ring around the piston rod and which are firmly connected to it. These magnets are preferably rod-shaped formed and extend parallel to the longitudinal axis of the piston rod 5 as in Figure 1 shown. The magnets each point an excitation coil 22, 23 to generate a magnetic flux within the respectively activated magnets.

For example, the magnets 20, 21, 40, 41, 42, 43,44,45, such as shown in Figure 2, be arranged at equidistant intervals on a disk 19, which has a central bore through which the piston rod 3 is guided. For this purpose, the piston rod 18 can have a circumferential shoulder with a thread in the end area have, the disk 19 being screwed onto the piston rod 3.

In this way, the magnets are firmly connected to the piston rod 3.

On the piston 8 is coaxially around the piston rod 3 in the area the transverse bore 25 a rotary valve 26 -arranged, which is sleeve-shaped is and which also has two through bores 31, 32 (Figure 2), which with the transverse bore 25 brought into congruence with a certain position of the rotary valve can be. To hold the rotary valve 26, the piston rod) can have another Have circumferential paragraph 48 at the height of the rotary valve. The top of the Rotary valve 26 has a certain number of cams 27, 28, 34, 35, 36, 37, 38, 49, 50, 53 or teeth that the pole pieces 47 of the magnets laterally directly face. The lower ends of the magnets protrude or overlap the Cam of the rotary valve. Thus, the magnets form together with those sitting on them Excitation coils have an external stator 39, the rotary valve with the cams one internal rotor of a stepper motor, the cams in turn being the pole pieces of the rotor. For example, in Fig. 1, the magnetic circuit is closed via the magnet 20, the cam 27 of the rotary valve 26, the cam 28 of the rotary valve, the inversely excited magnet 29 and the retaining disc 19, which are made of magnetizable Material. The cams of the rotary valve, preferably in pairs opposing cams are magnetically short-circuited with one another. The magnets consist of known magnetic or end pieces 52 materials high permeabilities. In certain applications, the magnets can also be permanent magnets be whose magnetization is increased by the excitation coils when current flows. The design of the stepper motor can also be designed such that the Rotary valve as an external rotor, both the piston rod and the magnets includes. In this case, the magnets together with the excitation coils are more internal Running stator. Furthermore, versions are possible in which the magnets not arranged parallel to the piston rod, but for example radially to this are. The only thing that is decisive is the design of the movement mechanism for the rotary valve to train that the same can be rotated defined step by step via a control can, in order to cover the transverse bore within the piston rod to the desired extent.

Fig. 2 shows a section along the line A-A in Fig. 1, here the stepper drive is made up of eight magnets that are equidistantly spaced are arranged around the piston rod 2. The rotary valve 26 is for four steps designed. The magnets which are located opposite one another are preferably in opposite directions magnetically excited, so that the opposing pairs of magnets magnetic circuit is closed.

In FIG. 2, for example, at step zero, the opposite ones are Cams 34, 38 the pole pieces of the magnets, which are also opposite in pairs 40, 43 opposite. The next cam 35 on the disc is one step ahead the magnet 41.

At step one, for example, the magnet 41 and becomes magnetic in the opposite direction the magnet opposite is excited. This causes the cam to move 35 (and the opposite cam) in the immediate area of the pole shoe of the magnet 41, with the next following cam 36 one step before the next following one Magnet 42 stands. In step two the magnet 42 (and the opposite one) energized so that the cam 36 (and the opposite one) immediately opposite the Pole piece of the magnet 42 to lie comes. The next one is now available Cam 37 one step before the next following magnet 21. At step three, now the magnet 21 (and the opposing magnet 20) energized, so that the cam 37 directly opposite the pole shoe of the magnet 21 (and the opposite Cam is also moved relative to the magnet 20). This way you will be at the actuation of the magnets by the control circuit is always the row of magnets Drive through ascending and descending.

Of course it is possible to use the switching mechanism with a larger one or smaller number of magnets and also the number of steps of the rotary valve to optimally adapt to the desired conditions.

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

With the shock absorber according to the invention it is not necessary - but possible -from outside the same control variables, such as the speed, the acceleration or the speed to be fed to the control circuit.

All you have to do is enter the path, preferably also within of the shock absorber can be obtained. Because the only thing that matters is quick change of the flow cross-section and thus the rapid change of the stepper motor. if this responds before that which occurs in a shock absorber for motor vehicles maximum vibrations of approx. 10 to 12 Hz can be effective on the input or processing of a speed, acceleration or speed signal and only process a path-dependent signal as a control signal, which the relative movement of the piston in relation to the cylinder - wheel in relation to the body -proportional. In this case there is a real self-regulating shock absorber, to which only the supply voltage has to be fed from the outside. Therefore can In a motor vehicle, all four shock absorbers are self-acting independently of one another rules.

An acceleration sensor is only available at higher frequencies, for example only necessary from about 100 Hz, so if the shock absorber according to the invention is not for Motor vehicles, but rather for damping vibrations on rapidly vibrating machines or aggregates is used.

This means that each shock absorber can choose the optimal one, independently of one another Calculate attenuation according to requirements, e.g. road conditions and adjust the rotary valve accordingly. Except for the power supply so that all parts are integrated in the shock absorber itself.

The use of the conventional piston 8 with high and low pressure valve is therefore advantageous because in the event of a failure of the automatic control the damping function of the shock absorber is fully retained for its limit values.

The control circuit preferably comprises a microcomputer and / or a microprocessor that handles all control signals, speed, acceleration, Speed of the motor and travel of the shock absorber, processed and accordingly the magnets controls the stator, whereby the rotary valve for the current situation is optimally adjusted.

The torsion spring 30 is used, in particular, in the event of a failure the automatic electrical control moves the rotary valve into its closed position to rotate 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 come into action, with which the shock absorber is fully functional, however, designed for limit values, maintains.

Figure 3 shows a further embodiment of a self-regulating Shock absorber according to Figure 1, of which only the end piece of the piston rod in difference is designed for the shock absorber according to FIG.

An end piece 55 is arranged on the piston rod 3, preferably screwed in, which has a central blind hole 56. Inside this blind hole a valve 57 is arranged, with an additional one in the end part of the blind bore 56 Compression spring 58 can be arranged, which moves the valve 57 in a preferred direction namely to close the mouth of the longitudinal bore within the lower end 15 of the piston rod.

The valve 57 is at a positive damping curve, that is, when braking of the valve disk 57 opened from below. If the shock absorber swings out, so wants the damping medium from chamber 7 to chamber 6 via openings 31, 32 of the rotary valve 26, the bore 25 and the longitudinal bore 24 of the piston at full open rotary valve 26 flow back, the valve 57 is through the flowing Medium and / or the compression spring 58 moves down and abruptly closes the Muzzle of the longitudinal bore 24 from. The rotary valve is in its fully open position Position controlled. The decay process can now only via the valves 9 and lo within the piston 8 (Figure 1). 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 suddenly turns to The body moves so that the damping curve becomes positive again, so immediately The rotary valve is adjusted according to the calculated value. Since the valve 57 from If the damping medium is lifted off, the bypass is permeable again and it can a.new settling process to the previous, not yet completed settling process connect.

List of reference symbols 1 shock absorber 2 cylinder 3 piston rod 4,5 Brackets 6 lower chamber half 7 upper chamber half piston 9,10 valve bores 11, 12 valve springs 13 ring seal 14 motor 15 lower end of piston rod 16 Cylinder cover 17 ring seal 18 shoulder 19 disc 20,21 magnets 22,23 excitation coils 24 longitudinal bore 25 transverse bore 26 rotary valve 27,28 cam 29 lower end of the Magnets 30 torsion spring 31,32 bores inside the rotary valve 33 disc 34,35,36, 37,38,49,50,53 cams 39 stator 40,41,42,43,44,45 magnets 47 pole shoe 4e paragraph 46 Control Circuit 51 Hole 52 End piece 54 Accelerometer 55 End piece 56 Blind bore 57 Valve 58 Compression spring 59 Connections of the excitation coils - Blank page -

Claims (9)

P a t e n t a n s p r ü c h e P a t e n t a n sr 0 Self-regulating shock absorber, especially for motor vehicles, consisting of a cylinder closed at both ends, which is filled with at least one damping medium and with a piston rod, which is sealed into the cylinder and the one at its end on the cylinder side a piston sealed against the cylinder wall - possibly with a direction-dependent piston High and low pressure valves, which support the cylinder space in two chamber halves divides, the piston rod for -possibly additional- connection of the two chamber halves a longitudinal bore in the area of the piston and above it has at least two radial openings penetrating the longitudinal bore, which can be closed by an electrically controlled spool that is operated by means of on the piston rod arranged electrical coil is movable, characterized by the following features: a) the control valve is a sleeve-shaped rotary valve (26), which coaxially encompasses the piston rod (3) in the region of the openings (25) and the radial openings in its wall according to the number of openings (31, 32) which when the rotary valve is rotated relative to the piston rod the Open openings more or less, b) the rotary valve is a rotor Stepping motor formed, the stator (51) of a plurality of magnets (20, 21, 40, 41, 42, 43), each having an excitation coil (22, 23) and the the piston rod also surrounds coaxially, c) within the cylinder, preferably an electronic control circuit (46) is arranged within the piston rod (3), which sends the electrical switching pulses to the stepper motor depending on the entered Data such as Temperature or viscosity of the damping medium (s), path the shock absorber (1), speed and acceleration of the vehicle, for step-by-step rotation of the rotary valve. 2. Self-regulating shock absorber according to claim 1, characterized in that that the magnets (20, 21, 40, 41, 42, 43) of the stator (51) of the stepping motor are rod-shaped formed and supported at their upper ends on the piston rod (3) and are arranged circularly around the same and parallel to it, these excitation coils (22, 23) can be controlled individually or in pairs opposite each other and that the Rotary valve (26) is a sleeve with magnetizable cams along its circumference (27, 28, 34, 35, 36, 37, 38), the magnets being designed as an internal rotor The rotary valve protrudes up to the area of the cams and is designed as pole shoes (29) are 3. Self-regulating shock absorber according to claim 2, characterized in that the sleeve (26) at its upper end centrally a magnetizable disc (33) carries along its circumference the cams (27,28,34,35,36,37,38) which laterally inside the pole pieces (29) of the magnets (20,21,40,41,42,43,44) face. 4. Self-regulating shock absorber according to claim 2, characterized in that that the rotary valve is made of plastic and at its upper end a wreath made of magnetizable material which carries the cams. 5. Self-regulating shock absorber according to claim 1, characterized in that that the rotary slide (26) has a torsion spring (30) for resetting in a defined Has zero position. 6. Self-regulating shock absorber according to claim 1, characterized in that that an acceleration sensor (51) in the cylinder (2) is used to measure the acceleration is arranged. 7. Self-regulating shock absorber according to one of the preceding claims, characterized in that the rotary valve of the stepping motor is designed as an external rotor and encompasses the magnets of the internal stator. 8. Self-regulating shock absorber according to claims 2 or 3, characterized characterized in that the rotary valve (36) has a number of cams (27,28,34,35,36,37,38,47,48,49) carries the number or twice the number of steps to be performed in the Rotary valve (26) corresponds. 9. Self-regulating shock absorber according to one of the preceding claims, characterized in that the piston rod (3) inside in the area of the openings (25) a valve (27) for closing the openings in a preferred direction having.