FR2604401A1 - HYDROPNEUMATIC SUSPENSION FOR MOTOR VEHICLES - Google Patents

Abstract

THIS SUSPENSION IS OF THE TYPE WHICH INCLUDES AT LEAST TWO TELESCOPIC SPRING CYLINDERS 1 CONNECTED TO A PRESSURE ACCUMULATOR 7 BY A DUCT 16 AND DIVIDED BY A PISTON 3 INTO TWO WORKING CHAMBERS. TO ALLOW TO MODULATE THE DAMPING FORCE WHILE RETAINING THE ABILITY TO TRANSMIT THE FORCES IN ALL CONDITIONS, EVEN WHEN THE PISTON ROD EXTENDS QUICKLY, THE SECTION OF THE LINE 16 IS MODULATED BY A DAMPER ELEMENT 8 AND, D ' ON THE OTHER HAND, A BYPASS CONTAINS A VALVE 9 INCLUDING A SEAT 15 AND A MOBILE ELEMENT 10 WHICH HAVE SURFACES A1, A2, A3 SUCH THAT THE VALVE OPENS IF THE PRESSURE FALLS BELOW A VALUE GIVEN IN A 4 OF THE TWO WORKING ROOMS.

Description

The invention relates to a hydropneutral suspension

  for motor vehicles comprising at least two cylinders of telescopic springs arranged in

  the vehicle wheel region between the vehicle body

  and axles, wherein the telescopic spring cylinders are connected to a pressure accumulator by a pressure fluid line, and a damper piston attached to a piston rod divides the telescopic spring cylinder into two parts. rooms of

job.

  Shock absorbing devices are known for hydropneumatic suspensions of motor vehicles

  (for example DE-B-15 75 191, DE-A-23 22 997, DE-A-

  31 11 410) in which a damping element is provided

  in the connecting line between a cylinder of

  spring and a pressure accumulator. This amorphous element

  weaver is used to vary the damping force.

  In such systems, during retraction of the piston rod (compression phase), damping fluid is positively discharged into the pressure accumulator

  crossing the damping element arranged in the

  linkage. When extending the piston rod

  your (extension phase), the damping fluid, set in motion by the pressure gradient existing between the pressure accumulator and the working chamber of the telescopic spring cylinder, returns to the cylinder in

  crossing the damping element. If the speed of

  piston tension becomes greater than the value at

  what the loss of load in the damping element,

  which varies with the setting of the force-force characteristic

  speed of the damping element, is equal to the

  the main circuit in the accumulator at this time, the telescopic spring cylinder loses its ability to transmit force. This results from the fact that in the working chamber there is a vacuum at which gas is released from the damping fluid. The formation of vapor bubbles that

  produced in the working cylinder leads to

  heavy disturbances in the operation of the damping device. The object of the invention is to give a hydropneumatic suspension in which the cylinders of

  telescopic springs are connected with accumula-

  a pressure fluid line, a configuration which makes it possible to obtain an additional modulation of the damping force by means of the

  pressure fluid line, and in which the

  the transmission of forces remains in all working conditions, particularly in the

  where the piston rod comes out quickly (extension phase).

if we).

  To solve this problem, it is provided according to the invention that the passage section of the pressure fluid line can be controlled by an element.

  damper and that it is intended in a branch diversion

  in parallel with the damping element, a

  pe that includes a valve seat and a com-

  movable in axial translation, which cooperates with the valve seat, the control element having, for

  the control, surfaces that move the element axially

  if the pressure falls below a predetermined pressure in one of the two chambers of

  work, so that the derivation opens.

  In this configuration, one advantage is that the ability of the telescopic spring cylinder to transmit forces remains guaranteed in all operating conditions since, in the presence of a rapid extension of the piston rod, the fluid flow pressure does not pick up. Indeed, in

  this situation, the diversion established between the accumu-

  Pressure transmitter and telescopic spring cylinder

  opens, so that it can not establish itself

  in the working chamber of the telescopic spring cylinder. To obtain an additional order of the

  damping force, connected in series with the

  damping farts contained in the cylinder of

  telescopic fate, and according to another characteristic es-

  it is planned to use as a damping element

  the pressure fluid line, which

  then a section corresponding to a throttling, or

  well a valve that has choke holes

loaded by springs.

  In one embodiment of the invention,

  and according to a preferred feature, there is provided

  damping element, a variable damping device

ble adjustable.

  According to another embodiment of the invention,

  The control element of the valve has at least one surface loaded by the pressure of one of the working chambers and at least one surface charged by the pressure of the pressure accumulator. One advantage is that thanks to the configuration relationships

  established between surfaces, and by acting on the

  ports of the pressures that charge them respectively, one can choose a predetermined opening point for the

derivation.

  In one embodiment of the invention, the control element has a surface charged with atmospheric pressure as an aid for the surfaces charged by the pressures of the storage accumulator.

  pressure and the working chamber.

  In addition, it is expected that the element of

  Mande has a spring which acts in the closed position. In an advantageous embodiment of the invention, the damping element and the valve are

arranged in the same apparatus.

  Other features and advantages of the

  will be better understood when reading the description of

  FIG. 1 is a diagrammatic representation of a hydropneumatic suspension in which a bypass is provided in the connecting line between the cylinder of the telescopic spring. and the pressure accumulator; Figure la represents a detail corresponding to an alternative embodiment; FIG. 2 is a block diagram such as

  the one already shown in Figure 1, with this difference

  firstly, that it provides for a depreciable element

  in the connecting line between the telescopic spring cylinder and the pressure accumulator and, on the other hand, a valve in the bypass;

  FIG. 3 is a sectional view of the valve

  view in the derivation; Figure 4 shows another variant of a valve provided in the derivation; Figure 5 also shows a variant of a valve provided in the branch; FIG. 6 represents an adjustable damping element interposed in the connecting pipe between the telescopic spring cylinder and the accumulator of

  pressure, and a valve mounted in the bypass cor-

  corresponding, this element and this valve being both arranged in the same device;

  FIG. 7 is a schematic diagram representing

  both the valve in its use in a circuit of

correction of attitude.

  The diagram in Figure 1 represents

  a telescopic spring cylinder 1 and an accumula-

  7, which are connected by a pressure fluid line 16 in a branch of which a valve 9 is arranged. The assembly may constitute a

  attitude correction circuit which includes a correction

  19, a pump 20 and a reservoir 13. The telescopic spring cylinder 1 is constituted by a monotube damper, the piston rod 2 carrying a piston

  damper tone 3 which divides the cylinder into two chambers

  4 and 5, while in the damper piston are provided rolling channels which generate a damping force by means of valves

correspondents.

  A pressure fluid line 16 interpolated

  between the pressure accumulator 7 and the cylinder of

  telescopic spring 1 has a section corresponding to

  throttle or, as has been shown

  in FIG. 1a, this pipe comprises a section

  seducing a section corresponding to a strangulation. In parallel with the pressure fluid line 16, is

  provided a valve 9, mounted in a branch, and this-

  the valve is shown in detail in FIGS.

6 and will be described later.

  Figure 2 shows an example of how

  which corresponds in principle to Figure 1, with this

  The difference in the pressure medium conduit 16 is a damping element 8 which includes throttle holes 18 loaded by springs and intended to throttle the damping fluid. In all other respects, this embodiment corresponds to the hydropneumatic suspension shown in FIG. 1. In FIG. 3, there is shown in section a valve 9 which is arranged in a branch connected in parallel with the pressure fluid line. which connects the pressure accumulator 7 to the telescopic spring cylinder 1. The valve 9 is equipped with a

  control element or drawer 10 which is mounted to cut

  axially smooth in the body 21, in a bore 22.

6 2604401

  The surface Al serving for the control is loaded by the pressure of the working chamber, the surface A2 by

  the pressure of the pressure accumulator 7 and the surface

  this A3 by the atmospheric pressure. The surfaces A1, A2, A3 which are thus loaded by pressures are

  calculated so that the control element 10 is de-

  place axially as soon as the pressure prevailing in the cy-

  linder 1 decreases to a certain extent with respect to the pressure in the accumulator 7, so that

  the bypass connection between the pressure accumulator

  7 and the working chamber 4 of the spring cylinder

telescopic 1 is thus open.

  This opening pressure is defined by: P cylinder = P accumulator x A2 / A1

  with the proviso that A2 = Al - A3.

  As soon as the pressure in the working chamber 4 decreases with respect to the pressure in the pressure accumulator 7 according to the factor A1 / A2., The control element 10 moves, and the flow connection is opened. entered channel 23 and the canal

  26, passing through the cavity 24, along the seat of

  pope 15, and through the cavity 25. The seal

  14 serves to isolate the control element 10 from the atmosphere.

sealed seal.

  The area ratio A1 / A2 is chosen from

  to avoid the formation of a depression in the

  working chamber 4 of the cylinder 1 of the telescopic spring

  that even considering the friction of the trim

sealing 14.

  In FIG. 4, a valve 9 is shown,

  in which the control element 10 is here also

  moving head in axial translation in a bore 32; here the pressure of the pressure accumulator 7 and the

  pressure of the working chamber 4 of the cylinder of

  telescopic fate 1 act on mutual surfaces

  opposite. A1 surface is loaded by pressure

  of the working chamber 4, the surface A5 by the pres-

  pressure accumulator 7 and the surface A4 by atmospheric pressure. The control element 10 is subject to the law that the opening pressure in the cylinder is equal to: P cylinder = P accumulator x A5 / A1,

  with the proviso that A5 = AI - A4.

  Figure 5 shows another variant of the

  pope 9, wherein the seat 15 of the valve 9 is on a shutter element 12 connected to the element of

  order 10 by means of a spring 11. In

  the position of the surfaces A2, A3, A5 loaded by the pressure that results from the construction, the opening point of the control element 10 of the valve 9 is located such that we have:

  P cylinder = P accumulator x (A2 - A5) / A2.

  Here, the surface A2 is loaded by the pressure of the pressure accumulator 7, the surface A3 by the atmospheric pressure and the surface A5 also by

  the pressure of the pressure accumulator. When the

  shutter 12 opens, the damping fluid

  flows through channel 23 and through cavity 24, it

  chit the valve seat 15 to enter the cavity, then through the channel 26, it gains the working chamber 4 of the telescopic spring cylinder 1. If we accept a

  small oil leakage current between the control element

  of 10 and the shutter element 12, this form of embodiment

  of the valve 9 makes it possible to obtain a friction-free opening and closing behavior and

therefore free of hysteresis.

  Figure 6 shows the integration of a

  8 and a valve 9 in a common apparatus 27. Here, the pressure accumulator 7 is connected

  to the telescopic spring cylinder 1 through the

  The channel 23 is disposed on the pressure accumulator side and the channel 26 on the working chamber side. When the derivation 17 is

  closed, the damping fluid flows between the

  In contrast, if the pressure prevailing in the working chamber 4 of the cylinder 1 falls below the value P cylinder = P accumulator × A2 / 23 and 26 by crossing the valves 28 and / or the throttling holes 18. A1 the control spool 10 moves axially and opens

  the communication between the channels 23 and 26.

  FIG. 7 shows the construction

  schematic diagram of a hydropneumatic suspension in which the working chamber 4 of the telescopic spring cylinder 1 is connected by the pressure medium pipe 16, on the one hand, to the pressure accumulator 7 through the damping element 8 , and, on the other hand,

  tank 13, through the valve 9. When the pressure

  sion in the pressure chamber 4 falls below

  under the value of the pressure prevailing in the accumu-

  7, the valve 9 opens and the damping fluid which must then flow into the working chamber 4 can arrive directly from the tank 13. In all other respects, the valve 9 corresponds in principle (with the exception of the surface charged by the pressure of the accumulator) to the exemplary embodiments shown

in Figures 3 to 5.

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

  just described as a non-limiting example.

  mitative without departing from the scope of the invention.

R E V E N D I CA TI 0 N S

  1 - Hydropneumatic suspension for vehicles

  vehicles comprising at least two cylinders of

  telescopic spells arranged in the vehicle wheel region, between the vehicle body and the axles, wherein the telescopic spring cylinders

  connected to a pressure accumulator by means of a

  te of pressure fluid and a damper piston fixed

  to a piston rod divides the spring cylinder teles-

  in two working chambers, characterized in that the passage section of the fluid conduit of

  pressure (16) can be controlled by a damping element

  (8) and that there is provided in a branch (17) connected in parallel with the damping element (8), a valve (9) which comprises a seat (15) and an element

  control device (10) movable in axial translation, which

  father with the valve seat (15), the control element

  of (10) having, for the control, surfaces which axially move the control member (10) if the pressure falls below a predetermined pressure in one of the two working chambers (4, 5), so

that the bypass (17) opens.

  2 - Hydropneumatic suspension according to the claim

  1, characterized in that the pressure medium line (7) comprises, as damping element (8),

  a section that corresponds to a strangulation.

  3 - Hydropneumatic suspension according to the claim

  1, characterized in that there is provided as a damping element (8) a valve which has

  throttle holes (18) loaded by springs.

  4 - Hydropneumatic suspension according to the

  1, characterized in that it is provided, as

  damping element (8), a variable damping device

ble adjustable.

  Hydropneumatic suspension according to claim 1, characterized in that the control element (10) of the valve (9) has at least one surface (Ai) charged by the pressure of one of the working chambers (4). , 5) and at least one surface (A2, A5) charged by the pressure of the pressure accumulator (7).

  6 - Hydropneumatic suspension according to the

  5, characterized in that the control element

  (10) has a surface (A3, A4) loaded by the pressure

atmospheric pressure.

  7 - Hydropneumatic suspension according to the

  1, characterized in that the control element (10) has a spring (11) which acts in the position

closure.

  8 - Hydropneumatic suspension according to the claim

  1, characterized in that the damping element

  (8) and the valve (9) are arranged in one and the same

mera.