FR2635298A1 - SUSPENSION FOR VEHICLES HAVING A SUSPENSION LEG BETWEEN THE BODY AND AN AXLE - Google Patents

Abstract

The upper and lower pressure chambers in a suspension strut are connected to each other through a check valve and are further connected to a pressure accumulator (accumulator spring). According to the invention, there is provided an adjustment slide 11 having at least one variable passage section f1 (s), f2 (s), f3 (s), which is hydraulically controlled by an adjustment pump 12, itself moved. also by a hydraulic control 13 which is supplied by the excess pressure fluid resulting from the compression of the suspension strut 10. The entire pressure fluid circuit in the suspension strut 10, the adjustment slide 11, the control pump 12 and the control 13 is closed from the outside.

Description

The invention starts from a suspension for vehicles, comprising

  a suspension strut disposed between the body and an axle and having a working cylinder in which a piston with a piston rod slides and which contains

  upper and lower working pressure, compared to

  your, which are connected to each other through a check valve

  and, in addition, to a pressure accumulator (accumulator spring).

  Suspensions known for motor vehicles

  separate units for suspension and damping of wheel masses; however, it is also known from

  combine suspension and collective damping components-

  in a suspension strut (acting hydraulically). The multitude of suspension concepts, from simple spring-loaded dampers to complicated units combining suspension and damping, can be divided into three categories. The first includes so-called passive suspensions, which are the most

  in which, in order to influence a process of sus-

  Pension taking place quickly, there is no energy supply

  considered in this sense as external, or on which

  From the outside, it can only operate slowly, and in which separate dampers, possibly in integrated form, have been provided for the damping. Such a passive suspension can be adjusted in a wide range of different flexibilities and different damping characteristics, for example to obtain a hard suspension with soft damping or vice versa, according to the requirements as to the comfort of the passengers or in agreement with the vehicle concerned. These suspensions

  Passives also include conventional oleo-pneumatic springs

  which can be supplemented by level corrections.

  A second category of suspension for

  takes what are called semi-active suspensions whose

  The principle is to vary appropriately, through

  quick adjustment of the damper, the temporal pace of the clean energy transformed during the suspension process. The

  semi-active suspension attempts to simulate a kind of

  active suspension by modifying - at the instant o because of the instantaneous running of the suspension, the contribution of external energy, therefore the active variation of the suspension action would be necessary - existing damping possibilities, so that the inadequacy is reduced to a minimum (DE-OS 35 24 862). Such a semi-active suspension can already place considerable demands on external adjustment operations and in particular require fast switching valves capable of operating in accordance with the frequency of operation.

  wheel rotation. It is necessary in addition to detecting

  wheels and bodywork and to introduce them into the

  the entire electronic control of the semi-suspension

  active. The third category includes so-called suspensions

  active, on which we actually intervene from outside

  - when the instantaneous unwinding of the suspension makes it necessary - not only by adequate control element settings, but also by the active supply of energy from outside to the suspension zone, for example by an elevation the pressure of the hydraulic oil under the effect of a pump, so that the force attacking the wheel is variable. This however requires the forecast of hydraulic power sometimes very high, likewise

  than the use of expensive control elements.

  Starting from this situation, the present invention aims to provide a suspension for vehicles such that not only

  we can completely dispense with the contribution of hydrau-

  external resources, but that while reducing the expenditure required for the control

  with a suspension strut whose flexibility and cushioning

  are variable and suitable for the application of freely selectable control strategies,

  which requires only a very small - or even

  order from the outside. The contribution of hydraulic energy

  from the outside must have Place only for the purpose of correcting

  any level present.

  According to the invention, these results are obtained by the fact that the suspension comprises a regulating slide having at least one variable passage section, that the adjustment slide is hydraulically controlled by a control pump, to which a control is also coordinated. hydraulic, the hydraulic control for the control pump is derived from the excess amount of pressure fluid obtained during the compression of the strut, the pressure fluid circuit in the strut, the adjusting spool, the

  The adjustment pump and the control

  outwardly, and that the variable passage section in the adjustment slide connects the two work pressure chambers of the

suspension.

  A suspension thus achieved has the advantage that, apart from

  possible pressure injection by a pump and a compression valve

  a co-ordinated level correction device, the common hydraulic circuit formed by the units

  control and suspension strut, is completely closed

  from the outside and the possibilities for determining the flexi-

  variable suspension and variable amortization result from a sort of finely tuned autonomous control,

  in the course of the suspension process,

  ask for an all-or-nothing command, from the outside, of a throttling for the change of flexibility

of the suspension.

  The system according to the invention nevertheless allows the development and application of a multitude of possible adjustment strategies for a strut, depending on the design of the components used, the pressure conditions, the sections

throttling and so on.

  The driving force required to control the passage sections of a control slide, sections which can influence both the flexibility of the suspension and the damping of the strut, is provided by a control pump control, which is itself pressurized by the work of

  the suspension strut, during its compression, the movement elas-

  return of the suspension strut allowing at the same time the return of the adjustment drawer to the starting position according to

  temporal functions, in optimal agreement with the action of

  instantaneous reaction and with particular events during the

cessation of suspension.

  The invention makes it possible, by eliminating expensive control elements, for example fast solenoid valves, from

  create a system of economic suspension and apply

  system-specific adjustment rules for controlling

  excitement of the suspension strut occurring in the

  practical operation. Since these strategies can take practical

  all the desired shapes, the concept which is at the basis of the present invention allows the use of a multitude of

  adjustable parameters, so that a spectrum as wide as

  This can be covered in the area of desirable control strategies. A possible adjustment strategy is as follows: 1. The flexibility of the suspension can be designed to decrease as the excitation frequency decreases; 2. It is also possible, in the same way, to ensure that the damping increases when the excitation frequency decreases; 3. If there is more than one successive excitation oscillation and is almost similar on the strut, the effects according to points 1.) and 2.) can be amplified according to a temporal function, up to prefixed Limits values. , not to be exceeded; exceptions may be made for suspension actions which are recognized in a timely manner as special events by the application of particular signals, which will still be dealt with under point 6.); 4. the appearance of the temporal function mentioned in

  3.) can be set so that the transition to low frequency

  excitation time lasts longer than at high excitation frequencies - the exception of point 6.) is also valid in this case; 5. the influence of the excitation amplitude can be kept lower than that of the excitation frequency, so that, after exceeding a predetermined threshold amplitude by

  design, influence according to points 1.) and 2.) is considered

  weakened or suppressed (special events); 6. in the case of suspension actions recognizable very early as particular events in the suspension, because of the application of particular signals, as mentioned,

  quick intervention - overlaying basic regulation -

  can be performed on the flexibility of the suspension; since these are separate events that can be defined unambiguously and can also be clearly noted by their effect over time, this intervention can consist of an all-or-nothing command between prefixed limit values. in the course of the process; the events in question may be, for example, the passage of a turn (which is detectable by the measurement of lateral accelerations for example), a braking, an acceleration, the arrival on a section of road whose state differs completely, and so on; 7. the intervention on damping according to point 2.) can be differentiated for compression and expansion, depending on the design of the various components used, so that

  the depreciation increases more strongly in the relaxation than in the com-

  pressure; and 8. to compensate for load differences, it is possible to provide a level correction, in particular of the slow reaction type, in the sense of the usual design, whereby, after the correction of the level as a result of an increase in the charge,

  the overall level of flexibility of the suspension is noted.

  According to a particularly advantageous characteristic, the suspension according to the invention comprises a main pressure line connected directly to the upper working pressure chamber of the strut, which produces a pressure during compression of the suspension strut, which leads to from which is controlled The adjustment drawer for the execution of a movement of movement of the drawer during the compression of the leg, the control possibly taking place with the interposition of several reports of multiplication or multiplication of

pressure.

  According to another characteristic, the adjusting spool, working at the excitation frequency of the strut during compression and expansion thereof, has at least three sections of passage: a first section for the determination of the flexibility of the suspension, a second section for the determination of compression damping

  of the strut and a third section for the determination of

  Nation's damping to the relaxation of the strut.

  According to a particularly advantageous embodiment, the suspension comprises a first accumulator spring connected to the main pressure line (through a check valve) and, to vary the flexibility of the suspension, there is provided a

  second accumulator spring in addition, Which is connected to a con-

  leading to the first accumulator spring through the passage in the regulating slide whose section decreases as the

  moving the drawer from its starting position increases.

  It goes without saying that other adjustment strategies, or modifications of the strategy indicated above, are possible without problems. A particularly advantageous aspect of the object of the invention is the overall hydraulic design of the system with the strut which is both a driving member, providing

  the energies necessary for the command, and controlled organ.

  Other features and advantages of the invention

  will be clearer from the following description of a

  non-limiting example of embodiment, as well as the single figure

  d_. drawing, showing, in part schematically, the concept of

  of a suspension strut with flexibility and damping

  variables in a closed pressure fluid circuit, with a

  detail shown separately on the adjustment drawer for

the limitation.

  The basic concept of the present invention is the use of

  The hydraulic pressure energy provided by a strut for controlling, in a closed hydraulic circuit, the flow of pressure fluid from and to the two working pressure chambers of the strut, to allow the creation of a suspension strut variable flexibility and damping and by means of which one can apply a large number of different adjustment strategies, with adjustment of the damping by means of a continuously adjustable throttling and, additionally, with an additional intervention

  controlled by an additional controlled throttle.

  silence, to influence the flexibility of the suspension in the

a yes-or-no function.

  The drawing represents the main components indicated

  below, which are hydraulically connected to one another and which

  Together, they constitute the essential part of a suspension according to the invention, comprising a suspension strut with variable flexibility and damping, as well as, if desired, the possibility of operating control operations from the outside. Said components are: a strut 10 and a control slide 11 which controls, by at least one variable passage section, connecting pressure lines between the two working pressure chambers

  formed by the strut and other hydraulic components

  of the system, an adjusting pump 12 for the control of the

  drawer 11 and a control 13 for the pump, which control can also

  It should be considered as part of the control pump.

  The assembly is completed by a first base accumulator spring 14 and a second accumulator spring 15, which can be added to the circuit in a continuous manner by the regulating slide and also, if desired, by an all-or-nothing control. for example, at

  means of outside intervention, a number of

  Hydraulic connection lines - described in detail in the following - between components, as well as check valves

incorporated in these pipes.

  The strut 10 may have a basic structure

  conventional mental and includes a working cyclider 16 in which is guided to be able to slide a piston 17

  provided with a piston rod 17a. When considering, in order to facilitate

  understand that the working cylinder 16 is mounted stationary (by a hinge) on the bodywork, in 18, one

  obtains, with respect to the piston rod 17a, due to the displacement

  piston 17 in the working cylinder, depending on the current suspension action at a given moment, a compression in the direction of a stroke + s or an expansion in the direction of a stroke -s, the eye 17 'of the piston rod, located opposite the point 18, being fixed for example to one side of an axle of a vehicle. Sensors may be provided for detecting instantaneous values of strut elastic strokes, frequencies and amplitudes, as well as, to the extent necessary, velocity and acceleration values of instantaneous elastic travel, compression and / or detent, and other leg or vehicle data (steer wheel deflection, brake pressure) to convert the detected values and to send signals

  corresponding to a control logic circuit 19, which is only

  schematically indicated (it may be a computer or a microprocessor controlled programmatically for example), also to act accordingly on circuit components accessible to an external command, if this is necessary in the context of the system global hydraulics. This aspect will be discussed in more detail later. A sensor for detecting races, frequencies, speed values and others, is shown schematically

in 20.

  Due to the tight fitting of the piston 17 - and the piston rod 17a, of course - in the working cylinder 16, an upper working pressure chamber 20a and a lower working pressure chamber 20b are obtained. piston being designated D4 and that of the piston rod being designated D5. The average system pressure or equilibrium pressure, prevailing throughout the system when the piston rod 17a does not move, is designated PF and may take different

values during operation.

  It should be noted here that the provision quite parti-

  As shown in the drawing of the pressure lines between the strut 10, the adjusting spool 11 and its control, as well as the accumulator springs, this is merely a possible, although preferred embodiment of the present invention, but that The invention is in no way limited to this circuit with these particular links. According to the basic design illustrated here,

  the adjustment drawer closes or opens (continuously)

  flows which consciously influence

  on the one hand the suspension flexibility of the system and on the other hand the compression damping and the relaxation (from

separate way).

  In the exemplary embodiment shown, but the invention

  tion is not limited, the control slide 11 has several, for example three controlled sections f1 (s), f2 (s), f3 (s), dependent on the displacement s of the drawer and can be s, it goes of self, any pace of desired section, according to the design. In the example shown here, the section f 1 (s ?, variable

  with the movement of the drawer, serves to fix and change the flexi-

  suspension of the system, section f2 (s) is used to fix or

  adjust the damping of the strut during the

  pressure of it (so in the + s direction), while the section

  f3 (s) is used to adjust or fix the amortization

  to relax, that is to say during the movement of the strut in the direction -s. As a first approximation, the sections

  represented in the drawing, including in their coordination

  relative nation, may be regarded as

  for the embodiment described hereinafter. When the slide 11 moves downwards in the bore 21 of the not shown body of the distributor in which the adjusting slide slides, the passage section or controlled section f 1 (s), assigned to the suspension flexibility, gradually decreases. , while the other two passage sections f2 (s) and f3 (s) increase more and more. The conditions indicated previously under points 1.) and 2.) are taken into account. Of course, according to the design of the various components of the entire system, the raising of the excitation frequency of the work of the strut may have the effect that the adjusting spool 11, in

  its movement as a function of time, can no longer perform a complete

  or only to a small extent

  return - from the position shown on the diagram.

  sin -, so that the section f1 (s) is throttled more and more and the sections f2 (s) and f3 (s) remain more and more at an open position as the frequency of excitation

gets up.

  Indeed, as apparent from the drawing, the passage section f1Cs), assigned to the flexibility of the suspension, connects the

  second accumulator spring or additional accumulator spring

  15, by a hydraulic connection line 22 at the point of

  connection 23 and via the pipe 23 'and a controlled throat 24 -

  described in more detail in the following and presenting a section

  Variable throttling f (P) - at first accumulator spring

  14, so that the parallel connection of these two springs

  emulators 14 and 15, when the passage section f1 (s) is open, obviously have a softer suspension behavior

  only when section f 1 (s) cuts or progressively shuts out

  cooks the additional accumulator spring 15 thus reducing

  its influence on the average global pressure in the system.

  It is possible and preferable to carry out the controlled throttling 24, already mentioned above, so that it puts the additional accumulator spring 15 in or out of circuit abruptly, by the variation of its section between limit values, in the sense of an all-or-nothing function, which poses only very limited conditions to the operation and capabilities of the electronics controlling the throttling 24 and thus allows an economic realization. However, it goes without saying that a continuous adjustment of the controlled throttle 24 is possible also in the

  framework of the invention. Anyway, the command of Strangles-

  24 provides the advantages and meets the requirements of point 6 of the adjustment strategy indicated above. It should also be noted that the passage sections controlled by the movement of the drawer 11 can also change in the same direction when moving this drawer from or to its starting position. The structure of the adjusting spool 11 is completed by a lower pressure chamber 25 which is directly connected by a connecting line 26 to the main pressure line 27, which is also connected directly to the chamber

  upper working pressure 20a of the strut 10.

  In addition, the lower pressure chamber 25 of the spool 11 is connected through a bypass line 28 and a throttle

  bypass 29 contained in this line and presenting the sec-

  fByp, at the upper pressure chamber 30, the lower chamber 25 being formed by enlarged portions of

  the bore in the distributor body for the drawer.

  Finally, the lower pressure chamber 25 of the slide contains a prestressing spring 31, producing a force K3, which pushes the

  drawer in the direction of its starting position,

milk at its deviation s.

  The adjustment spool is controlled by a pressure PR in the upper pressure chamber 30, which is higher than the pressure of the system PF and is produced by the control pump 12. The latter comprises a piston 32 controlled hydraulically. , slidably mounted in a bore 33 - only indicated schematically - of the adjusting pump 12 and delimiting a working pressure chamber 34 connected through a first

  retaining valve forming a suction valve 35 to the con-

  main pressure draw 27 and through a second check valve forming a discharge valve 36 to the

upper pressure of the drawer 11.

  The piston 32 of the pump 12 is also preloaded adequately by a spring and is mounted in a chamber of

  intermediate pressure 37 larger, forming part of the

  Mande 13 of the adjusting pump, the prestressing spring being designated 38 and producing a force K2. The piston 32 projects into this chamber 37 from its bore 33 plus

  narrow and ensuring its guiding in the manner of a cylinder; the res-

  preloading device 38 is supported on one side by a spring cutter 29 carried by the piston 32 and on the other side on the bottom

of the pressure chamber 37.

  The pressure PA prevailing in the chamber 37 is produced by the control piston 39 forming part of the control 13 of the control pump. Under the effect of the stepped bores in the control of the control pump and in the latter, with the diameter D1 for the control piston and the diameter D2 for the piston of the pump, a multiplication ratio of the pressure is obtained. This makes it possible to establish, by applying the pressure PF prevailing in the main line 27 to one side of the control piston 39, a pressure of the adjustment pump PR increased accordingly, which controls the slide 11, closes the valve of retainer 35 and moves the drawer 11 continuously to specific positions

  along the path of the adjustment slide, depending on the

  study of the compression stroke of the strut 10 or the excitation resulting from the practical operation of the strut, which may take any form; whatever in itself, such a spectrum of excitement can only be

treated statistically.

  The area of the control piston and the control pump is supplemented by another control valve 40, provided in the control piston and which opens when sufficient overpressure prevails in the intermediate pressure chamber 37 of the pump, with respect to the pressure PF in the main pipe 27, thus always creating a pressure balance of the components hydraulically coupled together and forming respectively the piston of

  control, adjustment pump and adjustment drawer.

  Another very important influence quantity for obtaining specific control strategies results, in the object of the present invention, from the prediction of a driving behavior.

  link 41 - whose section can be adjusted to constant values

  or be changed from the outside in steps or

  tinue - between the upper pressure chamber 30 of the adjustment spool, to which is applied the high pressure PR of the pump

  setting, and the PF pressure prevailing over the piston of com-

  13 or acting on it. More precisely, this connection between zones which may have different pressures is carried out in such a way that the mouth 41a of the connecting pipe 41 is on the bore in which the control piston slides in the region of the pump control. at a height which communicates at the starting position with an annular groove 42 of the control piston 39, which groove is connected through internal transverse channels with the space inside the piston, which serves at the same time at the reception and

  the mounting of the check valve 40 which has just been mentioned.

  The path that can be covered by the control piston 39, is carried out a complete race, corresponds to the dimension s indicated on p the drawing, which means that at the maximum stroke, the upper annular edge of the throat 42 closes the mouth 41a of the connecting pipe 41, complementarily to an additional covering su. This recovery rating is a quantity

  essential for obtaining the desired adjustment strategy.

  It is also apparent from the drawing that the maximum stroke s P of the control piston 39 is also limited by the fact that the lower edge of the annular groove 49 of the piston determines a communication with the pressure chamber 37 of enlarged shape, which causes an equalization between the two pressures PA and PF and

  a limitation of the stroke of the control piston 39 at this level.

  The connecting pipe 41 between the pressure chamber

  upper spool 11 and the pressure PF in the plunger

  mande 39 contains, in addition, an additional element which is also

  Very important for the desired control strategy, namely a second controlled throttling 43, which can also be

  preferably, so that it can be adjusted in such a way that

  continued by an action exerted from the outside. This second strangling

  The controlled order has a section f (a) which is continuously variable. In some cases, section f (C) can also be

constant or fixed.

  In this context, it is necessary to complete the description

  inlet and outlet pipes of

  controlled by the associated distribution edges of the adjustment drawer 11. Whereas, seen from top to bottom on the drawing, the first

  passage section f1 (s) connects the additional accumulator spring

  15 at the general level of pressure through the first

  controlled throttle 24, so that both springs accumulate

  14 and 15 are connected in parallel and that a connection 44 exists from the first accumulator spring 14 to the main

  27 through a check valve 45 opening in this direction

  tion, the second passage section f2 (s) of the drawer 11 connects the

  same connection point 23 - leading through the pipe 23 'to the first

  first throttle control 24 - through a connecting line 46 to the pressure chamber 37 of the adjusting pump 12, chamber 37 which, as already mentioned, serves at the same time to the hydraulic connection between the control piston 39 and the piston 32 of your

pump 12.

  The third passage section f3 (s) of the slide 11 connects, in the form of a parallel pipe 47, the pressure chamber

  lower work piece 20b to the upper work pressure chamber.

  20a of the strut 10, with prediction, parallel-

  at this connection, a check valve 48 which can open, according to the design of its opening characteristic, when the pressure in the upper chamber 20a is higher (compression). The structure described up to now is completed, finally, by the possibility of applying pressure from the outside through a feed line 49 in the overall hydraulic system described in the above, for the realization of a correction of level, the application of the pressure being produced by a pump and a control valve collectively designated 50. This level correction represents a slow adaptation of the pressure and constitutes, besides the controlled throttles 24 and 43 having the controlled sections f (p) and f (c), a third

  possibility of intervention from the outside, which makes it possible to

  refer to point 8.) of the strategy indicated at the beginning.

  In such a hydraulic structure, constituting

  together an adjustment system with pre-set parameters

  selected or accentuated for the implementation of

  desired adjustment levels, movements according to the

  speed, especially at the adjusting spool, also play

  Considerable role, aside from the possibilities of intervention from the outside, since the drawer is moved by a regulating pump which acts in fact according to the speed and that the drawer makes its movement of return under the effect of force

  of a jurisdiction - whereas, in that state, it is also equi-

  released under pressure - against adjustable throttles43 and 29 respectively having the sections f (cx) and f (Byp). It appears

  therefore, on the sections controlled by the drawer, a

  frequency of the frequency, which is exploited for the implementation of the desired tuning strategy and can be adjusted accordingly, also involving the throttling constriction 29 with the fByp section and the recovery rating s

already mentioned.

  It goes without saying that precise indications as to the

  weighting the parameters, enter into the field of indi-

  dimensional cations; such indications are not necessary.

  In addition, these values can be determined freely according to the adjustment strategy that is to be implemented on the basis of the adjustment system illustrated with the circuit.

  pressure fluid fully closed in itself.

  The fundamental feasible functional mechanisms are described below. The flexibility of the suspension can be varied, within certain limits, by switching on or off

  switch off the accumulator spring 14 without bearings, that is,

  to say continuously, or suddenly; this is achievable according to external influences related to the state of the roadway or by the desired choice of the behavior of the suspension

  during the walk (comfortable or sporty).

  The adjustment slide 11 operates at the frequency of exci-

  tation of the strut 10 and control, by the three sections provided here and varying with the displacement ss of the drawer (sections whose configuration can be chosen freely in the design), on the one hand the flexibility of the suspension, by f1 (s),

  on the other hand, in the opposite direction, depreciation at

  by f2 (s) and the rebound damping by f3 (s). The return speed of the slide, essentially determining the increase of the narrowing of the passage section f3 (s) and hence the rebound damping (through the pipe 47), depends solely on the spring force K3 , the diameter D3 (diameter of the spool of the adjusting spool), the section f (o) adjusted the controlled throttling 43 and the fByp section of the Syp

  bypass 29, ensuring with adequate delay the equalization

  the pressure chamber between the upper pressure chamber and the lower pressure chamber 25 on the slide 11. These are essential design parameters of the regulator thus created, of which the strut 10 is also an integral part, the advance, that is to say the displacement of the control slide 11 from its starting position being produced by the discharge of the pressure fluid by the control pump 12, Which generates a pump pressure PR which is higher that pressure in the rest of the system. The pump 12 is itself again hydraulically controlled by means of the "control control pump" which precedes it, constituted by the control piston 39 with the diameter D1, making a stroke sA which is limited to value

  sp, as explained above, by the establishment of a

* nication through the throat.

  Other essential features of the design of the regulator thus created, are the diameters D4 of the piston 17 of the strut, D5 of the piston rod 17a of the strut, D1 as the diameter of the control piston 39 , D2 as the diameter of the piston 32 of the adjusting pump, D3 as the diameter of the spool valve bearing surfaces, as well as the stroke sF as the amount of movement of the piston 17 in the strut 10 e. the path s as a dimension between P

  stops determining the maximum stroke of the control piston 39.

  This dimension also determines to an essential extent P the behavior of the entire adjustment system, in accordance with point 5 of the strategy indicated at the beginning, because this results in a reduction of the influence of the amplitude. of excitement, therefore of the race constituting the starting data - of the leg

suspension.

  With each expansion movement, the control piston 39 and the piston 32 of the adjusting pump 12 return, under the effect of the force K2 of the prestressing spring 38, in a non-throttled manner, in the opposite direction to the displacement SA, to the up to the integral stop of the cylinder provided for the control piston 39. If the expansion on the strut 10 continues, the return flow is made from the additional accumulator spring - also in the case where the Controlled throttle 24 is closed - unhindered, through the check valve 40 provided in the control piston 39 and constituting a relief valve. Due to the additional control of the return channel 41 by the second controlled throttle 43, the control piston 39, by its annular groove 42, acts on the return flow of the spool 11 since, at the maximum stroke s of the piston 39, the Return P-channel 41 is closed by throttle 43. This is where the overlap plays an essential role because when the return channel is closed, corresponding to the maximum displacement of the control piston 39 by pumping (it is Of course, the return flow can occur only through the bypass constriction 29 having the fByp section, so that the return speed of the spool, thus also the behavior in The time of the regulator in

  as a whole, are slowed down in this state of adjustment.

  It should also be mentioned here that the adjustment slide 11 also has a hydraulic limitation of the stroke, which is shown separately at the bottom right. It can be seen from this detail that When the drawer 11 reaches a maximum stroke Ssmax, which can be prefixed, the upper edge 11a of the bearing surface 11b directly delimiting the upper pressure chamber 30, discovers, that is to say establishes the communication towards the pipe 23 'on the downstream side of the second accumulator spring 15, which results in an expansion of the pump pressure PR'.

  produces a maximum run, there is still a

  residual side s' on the connection side with the second accumulator spring 15, so that in the opening area for the

  limitation of the stroke, the arrival from the second

emulator 15 is closed.

  In general, the ratios of the following diameters have been respected: D1> D2 and D2 <D3, the pressures having in this case the following relations: PA <PF and PR> PF 'It is also important to note that the control system

  thus formed, comprising the strut 10, also presents

  a setting characteristic imposed on the case where the section

  f (o) of the constriction 43 is constant, so that it is possible

  possible to find a design, for the hydraulic regulator, with which the whole spectrum can be covered

  simply with a constant section f (o). In this case, the variation

  the throttling section is not necessary, although points 1.), 2.), 3.), 4.), 5.) and 7.) previously mentioned are also satisfied with a throttle. which is fixed in this case, so that one can be satisfied with a simple electronic control, designed only for the switching function of the controlled throat 24 and complementarily

  for the level 50 correction. Even when an electronic variation

  of the throttling section f (c) must be provided, the

  The conditions to which the order must comply are

  compared to the usual means for direct switching solenoid valves and the control strategy that would then be required of a suitable electronic control device. The object of the present invention can dispense with the need for the extremely fast control of very large flows usually required for very sophisticated control strategies. The control process required for this purpose takes place, as described, in the controller

  hydraulic system, which can intervene continuously during oscillations

any individual elements.

  Finally, the section f (x) of the throat 43 can be slowly varied according to simple signals, for example as a function of the oil temperature or according to steps

selected by the driver.

  All characteristics indicated or represented in

  the description, the claims that will follow and the drawings,

  can be essential, both individually and in a com-

  any combination for the implementation of the invention.

Claims (22)

  A vehicle suspension, comprising a suspension strut disposed between the body and an axle and having a working cylinder in which a piston with a piston rod slides and which contains upper and lower working pressure chambers, relative to the piston, which are interconnected through a check valve and, in addition, to a pressure accumulator (accumulator spring), characterized in that it comprises a regulating slide (11) having at least one section of variable passage (f1 (s), f2 (s), f3 (s)), that the adjusting spool (11) is hydraulically controlled by an adjusting pump (12), to which a hydraulic control (13) is also coordinated ), that the hydraulic control (13) for the adjusting pump (12) is derived from the excess amount of pressure fluid obtained during the compression of the strut (10), the pressure fluid circuit in the leg suspensio n (10), the adjusting spool (11), the adjusting pump (12) and the control (13) of the adjusting pump being generally closed outwards, and that the variable flow section (f1 (s) ), f2 (s), f3 (s)) in the adjusting slide (11) connects the two chambers of   working pressure (20a, 20b) of the strut (10).   2. Suspension according to claim 1, characterized in that it comprises a main pressure line (27) connected directly to the upper working pressure chamber (20a) of the strut (10), which produces a pressure when of the compression of the suspension strut (10), from which is controlled from The control slide (11) for performing a movement of movement of the drawer during the compression of   the leg (10), the order possibly being made with   position of several reports of multiplication or multiplication pressure cation.   3. Suspension according to claim 1 or 2, characterized in that the adjusting slide (11), operating at the excitation frequency of the strut during compression and expansion of it, has at least three sections of passage: a first section (f 1 (s)) for the determination of the flexibility of the suspension, a second section (f2 (s)) for the determination of the compression damping of the leg of   suspension (10) and a third section (f3 (s)) for the determination   nation of the rebound damping of the strut.   4. Suspension according to any one of claims 1   to 3, characterized in that the adjusting spool (11) has a lower pressure chamber (25) and an upper pressure chamber (30) which opens through a check valve (36) as a check valve. backflow to the pressure chamber of   output (34) of the control pump (12).   5. Suspension according to any one of claims 1   to 4, characterized in that the upper pressure chamber (30), which is decisive for the return of the adjusting slide (11) to the starting position, is connected to the lower pressure chamber (25) by   a bypass line (28) containing a throttle constriction   vation (29) having a throttling section (fByp) and that, in addition, a return line (41) is provided parallel to this   diversion line, return pipe containing a foreign   controlled release (43) and which opens into the pressure chamber, connected to the main pressure line (2?), above or below   the inside of the control piston (39).   6. Suspension according to claim 3, characterized in that the passage sections (f1 (s), f2 (s), f3 (s)), controlled by the movement of the adjusting slide (11), change in the same meaning or in the opposite direction.   7. Suspension according to claim 3 or 6, characterized in that the first passage section (f1 (s)) closes more and more during an initial movement of the adjusting slide (11), while the other two sections (f2 (s), f3 (s)) open more and more, so that they vary in opposite directions by   report to the first passage section.   8. Suspension according to claim 5, characterized in that the controlled throttle (43) in the return line (41)   is adjustable quickly or slowly, continuously or abruptly is lying.   9. Suspension according to any one of claims 1   to 8, characterized in that a preloading spring (31) is arranged in the lower pressure chamber (25) of the adjusting slide (11) to produce a prefixed return force (K3) of the slide and that lower pressure (25) is connected directly to the main pressure line (27), presenting system pressure (pF).   10. Suspension according to any one of the claims   I to 9, characterized in that it comprises a first accumulator spring (14) connected to the main pressure line (27) (through a check valve 45), and that, to vary the flexibility of the suspension, a second accumulator spring (15) is additionally provided, which is connected to a pipe (22, 23, 23 ') leading to the first accumulator spring (14) through the passage in the adjusting slide (11), the section ( f1 (s)?   decreases as the drawer moves from its position starting point believes.   11. Suspension according to claim 10, characterized in that a second controlled throat (24) having a variable controlled section f (p)) is arranged in the connecting pipe   between the two accumulator springs.   12. Suspension according to claim 11, characterized in that the second controlled throat (24), connecting the two   accumulator springs (14, 15) with a view to varying the flexi-   bility of the suspension, can be brought abruptly from one to   the other of two limit values of the passage section.   13. Suspension according to any one of the claims   1 to 12, characterized in that a level correction device, comprising a pump and a control valve and serving to gradually increase the pressure of the system according to the state of   vehicle load, is connected to the main pressure line   (27), presenting the pressure of the system (pF), possibly at   through a check valve (45).   14. Suspension according to any one of the claims   1 to 13, characterized in that the upper working pressure chamber (20a) of the strut (10), reacting with a   pressure rise during compression of the suspension leg   is connected directly to the lower working pressure chamber (20b) through an opening check valve (48)   in the lower working pressure chamber (20b).   15. Suspension according to any one of the claims   I to 14, characterized in that the lower working pressure chamber (20b) of the strut (10) is connected to the upper working pressure chamber (20a) through the main pressure line (27) and a passage section (f3 (s)) which closes progressively upon the return of the adjusting spool (11) to its starting position, for the determination of the   damping behavior at the relaxation of the suspension.   16. Suspension according to any one of the claims   1 to 15, characterized in that the connection point (23) between the   accumulator springs is connected to an intermediate pressure chamber   diary (37) through another passage whose section (f2 (s)) decreases at the return of the adjusting slide (11) to its starting position, for the determination of the damping behavior at the   compression of the strut (10).   17. Suspension according to any one of the claims   1 to 16, characterized in that the outlet pressure chamber (34), on which the piston (32) of the adjusting pump (12) acts, which chamber has a diameter (D2) which is smaller than the diameter (D1) of the control piston (39) is connected to the main pressure line (27) through a check valve (35)   acting as a suction valve.   18. Suspension according to any one of the claims   1 to 17, characterized in that the control piston (39) of the hydraulic control (13) for the control pump (12) contains a check valve (40) which communicates the intermediate pressure chamber (37) with the main pressure line   (27) when the pressure is higher in the intermediate chamber   and that an annular groove (42) is provided on the control piston (39) to limit the maximum possible displacement (sp) of this piston as soon as this groove establishes the communication allowing the pressure equalization with the chamber intermediate pressure (37). Suspension according to claim 18, characterized in that the connecting line from the first controlled throttle (43) is cut from the upper pressure chamber (30) of the adjusting spool (11) in the region of the piston. control (39), during a maximum displacement (s) of this piston, with a P overlap (sU) prefixed, for adjusting the return speed of the drawer (11).   20. Suspension according to any one of the claims   1 to 19, characterized in that the adjusting spool (11) is provided with a stroke limitation produced by the communication of the upper pressure chamber (30) with the discharge line from the second accumulator spring (15). ), which can be switched on additionally, with simultaneous recovery of the arrival of the   accumulator spring on the passage section (f1 (s)) concerned.   21. Suspension according to claim 17, characterized in that a return spring (38) of a force (K2) prefixed attack   the piston (32) of the adjusting pump (12).   22. Suspension according to any one of the claims   I to 21, characterized in that it comprises at least one sensor (20) for detecting the elastic travel of the suspension, the speed of the compression, the frequency of the elastic movements and other data of the suspension strut (10). ) or the vehicle (turning of the steered wheels, brake pressure), a sensor whose output signals may be applied to an electronic control circuit, a computer, a microprocessor controlled by program or similar device, and which determines the three variables possible external influences, namely the elevation of the pressure by the correction of the level, as well as   the adjustment of the choke sections (f (oc)) and (f (p)) of foreign controlled elements (43, 24).