FR2557036A1 - HYDROPNEUMATIC SUSPENSION WITH LEVEL ADJUSTMENT FOR VEHICLES - Google Patents

Abstract

THE INVENTION AIMS AT GIVING A HYDROPNEUMATIC SUSPENSION AN APPROPRIATE CONFIGURATION TO ALLOW SIMPLE AND LEVEL ADJUSTMENT AND WHICH, WITH A VIEW TO IMPROVING THE ROLLING COMFORT, ENSURES AUTOMATIC REINFORCEMENT OF THE DAMPING OF THE VEHICLE IN THE EVENT OF DAMAGE. INCREASE IN THE LOAD AND AN AUTOMATIC DECREASE IN THE DAMAGE OF THE VEHICLE IN RESPONSE TO A DECREASE IN THE LOAD OF THE VEHICLE. TO SOLVE THIS PROBLEM, FOR THE CONTROL OF THE SETPOINT LEVEL, THE TELESCOPIC SUSPENSION CYLINDER 10 IS CONNECTED, ON THE ONE HAND, TO A PRESSURE FLUID PUMP 1 AND TO AN ADJUSTING UNIT 13 AND, ON THE OTHER HAND, TO A A PRESSURE ACCUMULATOR 4. IS PROVIDED, UPSTREAM OF THE TELESCOPIC SUSPENSION CYLINDER, A THROTTLE 12 CONTROLLED BY A PISTON 14 WHICH IS SOLICITED BY A FLUID UNDER PRESSURE AND BY AN INDEPENDENT PRESSURE, THE EFFECTIVE SECTION OF THE CHUCK 12 BEING REGULATED BY THE AXIAL TRANSLATION OF THE PISTON 14.

Description

The invention relates to a hydro-

  pneumatic with level adjustment for vehicles, in particular

  culier for motor vehicles, which comprises at least two telescopic suspension cylinders arranged in the region of the vehicle wheels and interposed between the

  vehicle body and wheel axles, each cylinder

  dre being optionally equipped with a shock absorbing device

  weaving, suspension in which, for control

  of a set level, the suspension cylinders

  lescopiques are connected, on the one hand to a pressurized fluid pump and to an adjusting member and, on the other hand, to a pressure accumulator, and which comprises a throttling member interposed upstream of the cylinder

  suspension and which regulates the cross section of an

  tercalé in the pressurized fluid line in operation

tion of the vehicle load.

  There are known devices intended to modify the damping force (for example, patent application

  R.F.A. published under number 31 11 410), in the-

  which the pressurized fluid pump introduces a liquid

  of damping in the suspension cylinders by

  through the pipes in such a way that the ti-

  the piston of the shock absorber is pushed back by the pressure

  which is established and that, in this way, the rear of the

  vehicle is lifted. This device gives the possibility-

  t to reach the setpoint level despite a modification

charging state of charge.

  One drawback of these devices is

  what the drawer dispenser is about a length

  relatively large space and in that it is inter-

  wedged upstream of the pressure accumulator in such a way that it is not possible to obtain a

  direct angular output, as is frequently the case

  stop for reasons of space. On the other hand, it

  there is reason to fear in this construction that the mem-

  brane which also determines the stroke in this case does not take unstable forms which are detrimental to the essential precision of the control stroke. In

  in addition, the throttle section is ordered exclu-

  due to the circuit pressure, so that the damping in the compression phase and in the ex phase

  voltage cannot be adjusted independently. At this-

  Added to this is the fact that during the production of the

  this damping, the control button exerts

  undesirable reaction forces on the separate membrane

trice.

  There are also known suspension cylinders

  fitted with an integrated damping valve, as-

  served with the load (for example, patent of the R.F.A. n 16 55 094) and which can be used in a closed circuit. This circuit acts on the suspension of the vehicle via a drawer distributor loaded by

  spring. Here, the depreciation of the vehicle is not in-

  fluenced. A hydropneumatic suspension of this kind includes

  cascading, one after the other, in operation

  charge, two or more than two accumulators

  pneumatic pressure which develop different pressures

  annuities, to get characteristics this way

more favorable elastic bands.

  Starting from this base, the object of the invention

  is to give a hydropneumatic suspension a cons-

  titution which makes it possible to obtain a level adjustment at

  both simple and safe and capable of ensuring automatic-

  ment, to improve ride comfort, increase the damping of the vehicle in response to the increase in load and decrease this

  amortization in response to a decrease in load.

  According to the invention, to solve this problem,

  the throttle member comprises at least one bore

  closing a piston movable in axial translation and a fac-

  this radial piston is stressed by an undue pressure

  dependent on the pressurized fluid line, the piston regulating the effective section of - the throttle

  the pressurized fluid line under the stress

and

  pressure medium / independent pressure

  te, and the closed part of the bore, which cooperates with the piston, is provided with a pressure balancing device. An advantage of this device is that the damping of the vehicle is automatically adjusted by means of the throttle member; more specifically, the throttle cross section shrinks in response to

  an increase in the load, that is, at an ac-

  pressure increases and this section gets bigger

  said in response to a decrease in load, without

  see react to the influences of the pressure of the damping

  sister. Thanks to increased depreciation in response to

  due to an increase in the vehicle load, the

  your vehicle weights can be more easily cushioned

  ties while the vehicle is running, so that

  holds a considerable improvement in road holding

  you. By the way, for example, excessive movements

  rollover of the vehicle body, are more damped

pidly.

  According to an essential characteristic of the in-

  vention, we obtain a simple and advantageous integration

  of the throttle when the bore is part of

  integral part of the telescopic suspension cylinder.

  In this case, a particularly advantageous effect is obtained.

  axial length when this bore is dis-

  laid transversely to the cylinder's working chamber

  dre of telescopic suspension. This arrangement is also advantageous for connecting the pipes.

  pressurized fluid. The effective cross-section of the

  glement then extends in the axial direction of the cylinder

  dre of telescopic suspension and perpendicular to the bore. According to another essential characteristic, the

  piston comprises at least two cylindrical parts pre-

  feeling different diameters. This brings advantages

  tages both for mounting the device and for

  axial guidance of the piston in its bore. By ail-

  their, the free space formed at the level of the part of smaller diameter at the same time forms the passage of the fluid under pressure between the fluid line under

pressure and strangulation.

  According to another essential characteristic,

  in the case of two bores in each of which slide

  is a piston, the throttles corresponding to the pha-

  getting extended and in the compression phase can be

  set independently of each other. This type of cons

  titution is particularly advantageous when the

  these amortization of the extension and compression phases

  of the telescopic suspension cylinder must be

  amortized and settled independently of each other.

  To obtain a simple method of soliciting the

  piston by independent pressure due to cir-

  cooked, and according to another characteristic of the invention,

  a radial face of the piston is biased by the

  atmospheric pressure which acts as an independent pressure

  pending. In this case, a cylindrical part of the piston emerges outside through a bore in which it forms a tight seal and it is stressed by

  atmospheric pressure. According to another characteristic

  that there is still the possibility of loading the piston by means of a compression spring in the direction

  tending to give its maximum section to the constriction.

  This guarantees that in the presence of a variation in the pressure

  circuit sion, the throttle is set to the value

  desired under the conditions considered.

  According to another essential characteristic of the invention, the independent pressure which solicits the

  piston is produced by a fluid pump under pres-

  if we. As a pressurized fluid pump, it is possible to use

  either an additional pump or the pump already

  present, if a drawer with cor- rect drawer is used

  respondent. An advantage of such an embodiment

  is that you can get an addi-

  tional damping forces desired in function

  tion of the increased vehicle load. According to a simple embodiment of the constriction, this constriction is constituted by at least one bore starting from the bore and opening into

  the working chamber of the telescopic suspension cylinder

spades.

  According to another essential characteristic of the invention, the pressure balancing device is composed of at least one bore which opens into the pipe for pressurized fluid and / or into the working chamber of the telescopic suspension cylinder. In the case of the use of two pistons, the holes provided for pressure balancing are arranged in such a way that the piston which influences the extension phase is balanced by a hole which opens into the working chamber and that the piston which acts on the compression phase is balanced by a drilling

  which opens into the pressurized fluid line.

  These holes provided for pressure balancing have the function, on the one hand, of avoiding compression in the presence of an axial displacement of the piston and, on the other hand, of not adversely influencing the independent pressure which acts on the piston. Furthermore, these

  drilling means that in the presence of an increase

  ment of the speed of the piston rod, the pressure differences generated demand each time the interested side of the piston and, in this way, generate a

  tendency to enlarge the section of the constriction-

  is lying. In this variant (FIG. 3), a double action is obtained on the section of the throttle since the piston reacts on the pressure of the circuit and on the damping pressure. This makes it possible to vary the damping characteristics to be produced more widely. In the case of the use of a single piston which acts in the extension phase and in the compression phase and o the telescopic suspension cylinder

  provides the main depreciation, and according to a characteristic

  essential tick of the invention, the piston is provided, as a pressure balancing device, with

  minus a recess which makes the two chambers communicate

  partial bres of the bore. An advantage of this embodiment consists in that the recess can be produced in the form of at least one bore or at least one groove or the like, so that the piston cannot generate compression. This device is free from reactions that can be produced by the

damping pressure.

  Other features and advantages of the

  vention will be better understood on reading the description

  tion which will follow from several embodiments and with reference to the accompanying drawings in which, Figure 1 is a schematic representation of a hydropneumatic suspension supporting all

  or part of the load and equipped with a level adjustment

  veal; Figure 2 shows an upper part

  a telescopic suspension cylinder fitted with an organ-

  no strangulation; FIG. 3 represents the upper part of a telescopic suspension cylinder, substantially

  conforms to that of FIG. 2 but provided with two orga-

  choke nes provided respectively for the phase

  extension and compression phase and which work-

  slow separately from each other; FIG. 4 represents the upper part of a telescopic suspension cylinder, substantially

  conforms to that of FIG. 1 but with this difference

  that it has double pistons and that the pressure

  pressurized fluid is transmitted through

  re of a rotary drawer distributor; Figure 5 is a detail view showing the rotary slide valve of Figure 4 in three different working positions;

  FIG. 6 represents an example of realization

  tion of the device shown schematically

in figure 2.

  The hydropneumatic suspension with adjustable level

  calf for vehicles which is intended to support the tota-

  part or part of the load, which is represented

  schematically in Figure 1 is essentially com-

  installation of the pressurized fluid pump 1,

  tes of pressurized fluid 2, of the adjusting member 3,

  pressure accumulators 4 and suspension cylinders

  pneumatic pension 5. The suspension cylinders

  lescopiques 5 each comprise a body 6 divided into an upper working chamber 7 and a lower working chamber 8, the piston rod 9 of this cylinder being articulated on a wheel guide member, not

  shown, while the body is integral with the case

  of the vehicle. The upper working chamber 7 and the lower working chamber 8 are separated from each other by a damping piston 10 fixed to the rod

piston 9.

  Figure 2 shows the upper part

  of a telescopic suspension cylinder 5, in which

  the upper working chamber 7 is separated from the

  lower working chamber 8 by the damping piston

  sement. The main depreciation is provided by the pis-

  tone of damping and by the corresponding damping valves 11. The damping controlled by the load is ensured by the effective throttling 12, the pressure of the line of fluid under pressure 2 acting on

  the piston 14 housed in the bore 13. The fluid line

  under pressure 2 is supplied by the pressurized fluid pump 1 and by the pressure accumulator 4, the

  piston 4 undergoing the action of the pressure of the accumulator

  tor while the atmospheric pressure acts on the radial surface 15. The compression spring 16 establishes a prestressing -oriented towards the limit position of the piston 14 in its bore 13. Atmospheric pressure

  which acts on the radial surface 15 of the piston 14 consisting of

  here kills a pressure independent of the circuit. Here, the piston 14 emerges outside the body 6, crossing

  a bore 18, by a portion 17 of smaller diameter.

  The seal is ensured by the O-ring 19. For

  avoid compression occurring in the

  closed tie 20 of bore 13, recesses 21 are metered

  swam in the piston 14. This exemplary embodiment pre-

  sees a unique choke that acts the same way

  in the extension phase and in the compression phase

  if we. In the presence of an increase in the load, it is necessary to introduce a greater quantity of fluid under pressure into the line of fluid under pressure 2 by means of the fluid pump under pressure 1, so that the body of the vehicle is brought back to its set level. In this case, a

  higher pressure in the circuit. The piston 14

  put to the prestress of the compression spring 16 is then biased over its diameter 17 which closes the seal

  the opening leading to the atmosphere; in this movement-

  ment, the compression spring 16 is more strongly tensioned and the effective section of the constriction 12 is

  scaled down. Under the effect of the reduction of the section ef-

  effective throttling 12, the damping force is greater, so that an improvement in the handling of the vehicle is obtained under the conditions of

full load.

  The preload of the compression spring 16 and the radial surface 15 of the piston 14 are variable quantities which can be adapted as a function of the type of vehicle considered and as a function of the conditions of multiplication of the force (amplitude of the movement of

  the wheel relative to the piston stroke). When we have

  dyes an extremely high pressure, the compression spring

  pressure 16 heels and thus limits the minimum opening of the effective throttle 12. The presence of the valves

  amortization 11 provides primary amortization

  determined for the telescopic suspension cylinder 5.

  In Figure 3, the upper part is shown

  of a telescopic suspension cylinder 5 of which

  the damping piston 10 works without a-

  mortification and o is used for the exchange of liquid between the upper working chamber 7 and the lower working chamber 8 an oil passage 23 with a constant section. Separate bores 13a and 13b are provided

  for amortization in the extension phase and for amortization

  weaving in compression phase. The piston 14a serves

  for compression damping and udder

  your 14b for the amortization in extension phase. The

  effective throttles 12a and 12b are provided accordingly

  quence. Also in this embodiment, the pistons 14a and 14b have radial surfaces 15a and 15b which are exposed to the atmosphere, as well as corresponding compression springs 16a and 16b. The

  closed parts 20a and 20b of the holes 13a and 13b pre-

  each feel pressure balancing. The balance

  pressure age of the closed part 20a occurs by

  through a bore 24 opening into the container

  pressure fluid 2 while the iron part

  mée 20b of the extension phase is provided with a drilling

  25 opening into the upper working chamber 7.

  The working mode of this example of realization

  tion corresponds to that shown in Figure 2; indeed, in the presence of an increase in the load, oil is here also pumped into the upper working chamber 7 by means of the pressurized fluid pump 1 and the pressurized fluid line 2, up to the vehicle body is brought back to its set level. In response to the increased pressure, the two compression springs 16a and 16b

  are constrained against atmospheric pressure

  that which acts on the radial surfaces 15a and 15b and the effective sections of the throttles 12a and 12b are

  thus reduced. By giving different characteristics

  with compression springs 16a and 16b and dimensions

  different sions on the radial faces 15a and 15b, it is possible to obtain different dampings in the extension and compression phases. Thanks to the holes 24 and

  , the strangulation interested in a given moment can

  gir at damping pressures, so that we have

  thus an additional possibility of action on

  the damping characteristic.

  Figure 4 shows another form of realization.

  sation, substantially similar to that already shown

  in Figure 3, but with this difference that the over-

  radial faces 15a and 15b are of an approximate dimension

  requested and solicited by atmospheric pressure by

  through passages 26a and 26b respectively.

  In this exemplary embodiment, the pistons 14a and 14b have three cylindrical parts. For controlling

  pressurized fluid, some functions are used

  additional tions a rotary drawer distributor

  27. The pressurized fluid line 2 is essential-

  comparable to that of the embodiment

  shown in Figure 3. In addition, there is provision

  conduits 28 arranged so as to urge the

  cylindrical ties 29a and 29b respectively of the pistons 14a and 14b. The pipe 30 and the reservoir 31 serve to balance the volume of the pressurized fluid driven in reciprocating motion by the pistons 14a and 14b and

  which, in this case, symbolizes at the same time the solicitation

tion of atmospheric pressure.

  In the position of the spool valve

  nant 27 which is shown in FIG. 4, the suspension

  hydropneumatic sion works in the way already shown

felt in Figure 3.

  Figure 5 shows three different positions.

* of the rotary drawer distributor 27. The position of the

  Figure 5a corresponds to that already shown in the figure

  gure 4 and it also corresponds to the form of realization

  sation shown in Figure 3.

  Figure 5b shows a position in which the pressure from the pressure accumulator is transmitted

  through the fluid line under pressure

  sion 2, to conduits 28 and, from there in addition to the par-

  ties 29a and 29b of pistons 14a and 14b. At this point, the damping of the vehicle is increased to a

  determined degree, i.e. made stiffer, with

  servicing of the depreciation of the vehicle subject to

  charge. In this higher stage of damping force-

  due to automatic adjustment, it occurs

  that a greater or lesser damping force

  ble depending on the vehicle load.

  Figure 5c shows the distributor at ti-

  revolving laughter 27 in a position in which a foreign control pressure can be applied to the

  parts 29a and 29b of the pistons 14a and 14b by the pipe

  te 32 so you can also get a hook

  depreciation subject to the charge which may

  ler until blocked. Foreign control pressure

  takes its reaction on a gas cushion 33, through the

  middle of the pipe 32, to make the pistons 14a and 14b work in the axial direction. The blocking

  pistons 14a and 14b and, therefore, that of the cy-

  liner of telescopic suspension on the pressure accumulator 4 allows the suspension to be used as a rigid support, for example, in the case of commercial vehicles equipped with a crane, so that the tilting torque is not influenced by unfavorable way

  by compression of the suspension.

  In Figure 6, there is shown an embodiment which corresponds to the diagram of Figure 2. It

  more precisely the telescopic suspension cylinder

  copy 5 in the interior volume of which the piston of a-

  mortissement 10 delimits the upper working chamber

  re 7 and the lower working chamber 8. The pipe

  of pressurized fluid 2 leads to the pressure accumulator

  sion 4 through its line 34 and to the pressurized fluid tank 5 or to the pressurized fluid pump 1 by

  line 35. The piston 14 is biased by the res-

  compression spell 16 and in this way controls the sec-

  effective constriction 12. Compression of

  the closed part 20 of the bore 13 is avoided by the evi-

  21. The arrival of pressurized fluid from the con-

  pressure fluid line 2 in the working chamber

  upper vail 7, as well as the evacuation of this fluid from the upper working chamber 7 to the pipe 2 occurs through the annular groove 36 and the

transverse drilling 37.

  The mode of action of the exemplary embodiment is

  lon figure 6 is in principle consistent with that already de-

crit with regard to figure 2.

  Of course, various modifications may be made by those skilled in the art to the device which

  has just been described only by way of non-binding example

  mitative, without departing from the scope of the invention.

  List of part numbers 1 Pressurized fluid pump 2 Pressurized fluid lines 3 Adjustment device 4 Pressure accumulator 5 Telescopic suspension cylinder 6 Body 7 Upper working chamber 8 Lower working chamber 9 Piston rod 10 Damping piston 11 Damping valves 12 Throttle 13 Bore 14 Piston 15 Radial surface 16 Compression spring 17 Cylindrical part of piston 18 Bore 19 O-ring 20 Closed part 21 Recess 23 Constant section oil passage 24 Bore Bore 26 Passage port 27 rotary drawer 28 Lines 29 Cylindrical part Line 31 Tank 32 Line 33 Air bag 34 Line Line 36 Annular groove 37 Cross drilling

2557036

Claims (9)

REVENDIC ATIONS   1 - Hydropneumatic suspension with level adjustment   calf for vehicles, in particular for motor vehicles   mobile, which includes at least two suspension cylinders   telescopic sion arranged in the region of the vehicle wheels and interposed between the vehicle body and the wheel axles, each cylinder possibly being   fitted with a damping device, suspension in the   which, for controlling the setpoint level, the cycles   telescopic suspension linders are connected, on the one hand to a pressurized fluid pump and to a member   on the other hand, to a pressure accumulator   sion, and which includes an interposed throttling member   upstream of the suspension cylinder and which adjusts the sec-   tion of a throttle inserted in the conduct of   pressurized fluid depending on the vehicle load   the, this suspension being characterized in that the organ-   no throttle comprises at least one bore (13)   closing a piston (14) movable in axial translation, a radial face (15) of the piston (14) being stressed by a pressure independent of the fluid line under   pressure (2), the piston (14) regulating the effective cross-section   ve of the throttle (12) of the pressurized fluid line (2) under the effect of the stress due to the pressurized fluid and the independent pressure and in that the closed part (20) of the bore which cooperates with the piston (14) is provided with a balancing device pressure.   2 - Suspension according to claim 1, charac-   characterized in that the bore (13) is part of the cylinder telescopic suspension (5).   3 - Suspension according to claim 1, charac-   characterized in that the piston (14) comprises at least two cylindrical parts (17, 29) having different diameters.   4 - Suspension according to claim 1, charac-   terized in that, in the case where there are provided two   wise (13a, 13b) each containing a piston (14a, 14b), the sections of the throttles (12a, 12b) corresponding to the extension phase and to the compression phase are   set independently of each other.   - Suspension according to claim 1, charac-   terized in that, for the formation of the inde   hanging, a radial face (15) of the piston (14) is stressed   cited by atmospheric pressure.   6 - Suspension according to claim 1, charac-   terized in that the piston (14) is biased by a compression spring (16) tending to push it towards the   position of maximum section of the throttle (12).   7 - Suspension according to claim 1, charac-   that the independent pressure acting on the piston (14) is produced by a fluid pump under pressure (1).   8 - Suspension according to claim 1, charac-   terized in that the throttle (12) is constituted by   at least one bore starting from the bore (13) and opening   edge in the upper working chamber (7) of the cylinder   dre of telescopic suspension (5).   9 - Suspension according to claim 1, charac-   that the pressure balancing device   sion is composed of at least one hole (24, 25) which   mouth in pressurized fluid line (2)   and / or in the working chamber (7) of the suspension cylinder telescopic board (5).   10 - Suspension according to claim 1, charac-   characterized in that the piston (14) is provided, as a   pressure balancing device, at least one   dement (21) which puts the two partial chambers of the bore (13) in communication.