FR2566062A1 - FORCE AMPLIFYING APPARATUS, PARTICULARLY FOR CONTROLLING A CLUTCH - Google Patents

Abstract

FORCE AMPLIFIER EQUIPPED WITH A SLIDING STROKE GENERATOR ELEMENT ACCORDING TO THE FORCE TO BE GENERATED, WITH AN AMPLIFICATION REGULATOR VALVE CONNECTED TO A PRESSURE SOURCE OF HYDRAULIC PRESSURE AGENT AND TO A TANK, SADITE AMPLIFICATION REGULATOR VALVE APPLYING A CONTROL PRESSURE, DELIVERED BY THE PRESSURE SOURCE, TO A PISTON-CYLINDER RECEIVER ASSEMBLY AS A FUNCTION OF THE STROKE CARRIED BY THE STROKE GENERATOR ELEMENT, CHARACTERIZED AS THE AMPLIFICATION REGULATOR VALVE 12 INCLUDES A CYLINDER 18 OF APPROPRIATE STAGE CONFIGURATION CONTAINING A STAGE 17 PISTON-DRAWER WHICH IS MOVED TOWARDS ITS REST POSITION BY A RETURN SPRING 22 AND WHOSE SMALLEST SURFACE 23 IS SUBJECT TO THE CONTROL PRESSURE, THIS PRESSURE BEING TERMINATED BY THE POSITION OF SAID PISTON-DRAWER 17 INSIDE THE CYLINDER 18, AND IN THAT THESE STROKE GENERATOR ELEMENT 11 APPLIES PRESSURE TO A PI TRANSMITTER ASSEMBLY STON-CYLINDER 16 WHOSE PRESSURE IS APPLIED TO THE LARGEST SURFACE OF THE PISTON-DRAWER STAGE 17, THUS ALLOWING THE LATEST TO SLIDE DEPENDING ON THE PRESSURE IN THIS PISTON-CYLINDER 16 EMITTER ASSEMBLY.

Description

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  The present invention relates to an amplification apparatus

  force fitted with a sliding pressure generating element

  depending on the force to be produced, a regulating valve

  amplification line connected to a source of hydraulic pressure agent pressure and to a reservoir, said amplification regulating valve applying control pressure, delivered by the

  pressure source, to a piston-cylinder receiver assembly in operation

  tion of the stroke traveled by the stroke generator element.

  The force amplification apparatus according to the present invention is in particular intended to be mounted in

  clutch master cylinder receiver cylinder units already e-

  existing which remain unchanged as such and are not

  complete only by mounting a force amplifier.

  The present invention therefore aims to provide a force amplification device of the type indicated above, making it possible to produce an amplified force in a receiver assembly

  piston-cylinder for which a master cylinder-cylinder unit

  sensor already functioning perfectly without force amplifier

  must only be completed by fitting a force amplifier.

  To achieve this object, the present invention provides that the

  amplification control valve includes a configurator cylinder

  appropriate stepped tion containing a stepped drawer-piston which is sol-

  licit in the direction of its rest position by a return spring and the smallest area of which is subjected to the control pressure, this pressure being determined by the position of the piston-drawer with

  inside the cylinder, and the stroke generator element applies

  pressure to a piston-cylinder transmitter assembly, the pressure of which

  Zion is applied to the largest surface of the stepped drawer-piston, allowing the latter to slide depending on the pressure

  prevailing in the piston-cylinder transmitter assembly.

  The ratio of the surfaces of the stepped piston-drawer is a para-

  meter of the pressure amplification achieved. The stepped piston-drawer is always in equilibrium, which means that the outlet pressure depends directly on the inlet pressure. In principle, the amplification regulating valve according to the present invention is

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  consisting of two two-way valves, one of which is normally closed

  one, leads to the pressure source and the other, normally open,

is connected to the tank.

  According to the present invention, the force amplifier can be installed without problem between a transmitter assembly.

  piston-cylinder and a piston-cylinder receiver assembly.

  An advantageous embodiment of the present invention is provided so that the piston-drawer acts on two ball valves, the first of which is open when the stepped piston-drawer is in the rest position and opens the connection between the piston receiver assembly -cylinder and the tank, and closes as soon as the piston-drawer leaves its rest position, and the second of which is located between the pressure source and the piston-cylinder receiver assembly and does not open until after the stepped piston-valve had closed the first ball valve, the second ball valve closing again as soon as the force exerted by the control pressure on the smallest surface of the step piston-drawer and on the return spring is in equilibrium with the force exerted by the input pressure on the largest surface. A particularly compact embodiment is obtained when the two ball valves are arranged parallel to one another at the bottom of the cylinder facing the smallest surface of the

stepped piston-drawer.

  Since the amplification regulating valve conforms to

  me to the invention uses only a very small volume when it is

  actuated by the piston-cylinder transmitter assembly, it is provided,

  formally to an advantageous exemplary embodiment of the present in-

  vention, to place a race simulator parallel to the amplification regulating valve. In accordance with the present invention, this racing simulator must, in particular, be designed so that

  the piston-cylinder transmitter assembly applies pressure to a receiver

  volume absorber which absorbs an additional volume of

  hydraulic pressure representing exactly the pressure generated by

  the piston-cylinder transmitter assembly.

  A particularly compact and nevertheless very

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  sensitive can be obtained in that the volume receiver understands

  a stepped cylinder incorporating a stepped piston, the largest of which

  face is subjected to the pressure of the piston-cylinder emitter assembly and whose smallest surface and the displacement stroke act on a pressure limiting valve device controlled by the stroke, so that the stroke traveled by the stepped piston is

  converted into pressure acting on the smallest surface of the pis-

your tier.

  In other words, the basic principle of the stroke simulator according to the invention is to convert a determined stroke of a stepped piston, by means of pressure amplification, into a back pressure limiting the consumption of volume. on the side of the largest surface of the stepped piston at a value which is necessary to obtain a desired stroke of the stroke generating element,

for example a pedal.

  In detail, the present invention provides that the pressure relief valve device includes a pressure relief valve.

  pressure limitation which is subjected to the pressure of the smallest

  te surface of the stepped piston and is connected to the tank, and which comprises

  te a stroke control input controlled by the stroke of the stepped piston. In this case, it is advantageous that a non-return valve

  opening in the event of overpressure in the piston-cy emitter assembly

  lindre is established between, on the one hand, the derivation starting from the piston-cylinder transmitter assembly and ending at the receiver of

  volume and, on the other hand, the amplification regulating valve.

  The characteristics previously indicated make it possible to-

  establish a pressure in the piston-cylinder receiver assembly with good sensitivity. To guarantee an irreproachable pressure drop after actuating the pedal, another

  embodiment of the present invention provides that the device

  pressure relief valve tif includes a pressure relief valve

  pressure which is subjected to the pressure existing at the inlet of the amplification regulating valve and is connected to the reservoir, and which has a stroke control input controlled by the stroke of the stepped piston. In this arrangement, the control pressure output of the amplification regulating valve is advantageously connected, through a non-return valve which opens in the event of overpressure at the control pressure output, to the pressure chamber of the cylinder. stepped which is subjected to the pressure applied by the smallest surface. In addition, a non-return valve opening in the event of

  overpressure at the pressure inlet of the limiting valve

  In this arrangement, the pressure must be located between,

  on the one hand, the pressure input of the pressure limiting valve

  sion subjected to the pressure applied by the stepped piston and, on the other

  part, the piston-cylinder transmitter assembly.

  Preferably, the non-return valves open for

  pressure difference of approximately 0.5 bar.

  The different objects and characteristics of the invention

  will now be detailed in the description which follows, made

  by way of non-limiting example, with reference to the appended figures which represent:

  - Figure 1, a partial sectional view of c8té of a val-

  amplification regulator designed to be used in the device

  force amplification signal according to this in-

  vention, - Figure 2, a schematic view, similar to a diagram of

  connection, of a power amplification device

form to the present invention.

  In accordance with FIG. 1, a stepped cylinder 18, the largest diameter range of which is closed in leaktight manner by an axial plug 40, is placed in the amplification regulating valve 12 according to the invention. A step-shaped piston-drawer 17

  corresponding is housed sliding inside the cylinder 18.

  Via an inlet 41 and a non-return valve 36, the largest

  surface 19 of the stepped piston-drawer 17 is subjected to the pressure

  picked up by a piston-cylinder emitter assembly 16 which is, for example

ple, controlled by a pedal 11.

  The pressure chamber 42 of the stepped cylinder 18 adjacent to

  the smallest surface 23 of the stepped piston 17 is connected to a connector

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  xion 43 leading to a piston-cylinder receiver assembly 15 and communication

  only with two ball valves 20, 21 located parallel to one another at the bottom of the cylinder 18 opposite the smallest surface 23. The ball valve 20 is adjacent to a connection 44 leading to a pressure source 13 constituted, for example, by a

pump 45 and by an accumulator 46.

  The ball valve 20 opens when the ball 47 is opened against the pressure delivered by the pressure source 13. To obtain this opening, a rod 50 is provided on the smallest surface 23 of the stepped piston valve 17, said rod 50 being, in the rest position shown in FIG. 1, clearly distant from

  the ball 47, so that the ball valve 20 is closed.

  Another ball valve 21 is provided which is placed by

  parallel to the ball valve 20 and whose ball 51 cooperates with a seat 52 and is connected to a drawer 53 which, by means of a stop 54, engages behind a counter stop 55 of the stepped drawer-piston 17 and which is pushed into the position represented in FIG. 1 by means of a helical compression spring 10 which surrounds the drawer 53 and which acts between the drawer 53 and the piston-drawer 17. The stop 54 is in this position, bearing against the counter-stop and the ball 51 is detached from the seat 52. The pressure chamber 42 is thus connected to a connection 57 leading to the reservoir 14. A space 56 provided between the stop 54 and the body of the staged piston-drawer 17 guarantees a sufficient stroke for the stepped drawer-piston 17 after closing the ball valve 21. A return spring 22 keeps the stepped drawer-piston 17 in the rest position shown

  in Figure 1 when no pressure is applied to it.

  When, when the pedal 11 is depressed, pressure is exerted on the largest surface 19 of the stepped piston-drawer 17 by the piston-cylinder emitter assembly 16 after the opening of a non-return valve 36 at a pressure of 0.5 bar, stepped piston-drawer 17

  moves to the left, considering figure 1, at the

  be of the relatively weak force of the return spring 22, after which the stepped piston-drawer 17 displaces the ball 51 to the medium

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  of the helical compression spring 10 and of the drawer 53 Until the ball 51 rests on the seat 52 and breaks the connection between the pressure chamber 42 and the reservoir 14. If the piston-drawer

  step 17 continues to move to the left, the stop 54 moves

  adhesive of the counter-stop 55 to move in the space 56, the helical compression spring 10 being compressed. In addition, the rod 50 finally touches the ball 47 of the ball valve 20 and takes it off from its seat 49. At this time, the pressure delivered by the

  pressure source 43 is sent through the ball valve 20 or

  green, via connection 43 to the piston-cylinder receiver assembly 15, the piston of which is moved accordingly. As soon as, in the pressure chamber 42, a pressure is established which, with the return force of the return spring 22, is in equilibrium with the pressure exerted on the largest surface 19, the valve to

  ball 20 is closed under the action of spring 48. The control pressure

  of at connection 43 is therefore proportional to the pressure

  input sion existing at connection 41. The force amplification is determined by the ratio between the smallest area

  23 and the largest surface 19 of the stepped piston-drawer 17.

  The elements of figure 2 corresponding to those of the fig-

  re 1 are designated by the same digits.

  FIG. 2 also shows that the piston 16 ′ of the piston-cylinder transmitter assembly 16 can be returned to the rest position by a return spring 58. In FIG. 2, the regulating valve

  amplification 12 according to Figure 1 is only shown dry

  matically in the form of a block.

  In addition to the embodiment according to Figure 1, a

  24 race simulator is placed parallel to the regulating valve

this amplification 12.

  To this end, a hydraulic line 59 starts from a bypass point 35 provided on the line leading from the piston-cylinder transmitter assembly 16 to the non-return valve 36 and terminates in a volume receiver 25 designed in the form of a cylinder. stepped 26 receiving a stepped piston. The hydraulic line 59 is connected to the pressure chamber 28 ′ which acts on the largest surface 28 of the stage piston 27. The smallest surface 29 of the stepped piston 27 acts

  on a pressure chamber 39 provided at the opposite end of the cylinder

  dre staged 2nd. A hydraulic line 60 which starts from said pressure chamber 39 terminates in a pressure limiting valve 32 of a pressure limiting valve device 30 and another hydraulic line 61 terminates in a non-return valve

  37, to the hydraulic line 62 which connects the connection 43 to the assembly

  ble piston-cylinder receiver 15. A piston rod 63 connected to the stepped piston 27 acts via a transverse bar 64 on the stroke control input 34 of the pressure limiting valve 32. In addition, the transverse bar 64 acts on the stroke control input 33 of another pressure limiting valve 31 of the pressure limiting valve device 30, said valve

  pressure limitation 31 being connected via a con-

  hydraulic line 65, 66 to connection 41 of the regulating valve

amplification 12.

  In addition, line 65 is connected to the hydraulic line.

  than 59 by a non-return valve 38.

  In addition, the two pressure limiting valves 31, 32

are connected to the reservoir 14.

  The dimensioning of the various constituent elements

  from the following functional description:

  When the clutch pedal 11 is actuated, the valve an-

  ti-retour 36 opens and produces a pressure corresponding to the level

  of connection41 of the amplification regulating valve 12. Simul-

  temporarily, a determined volume of pressure agent enters the stepped cylinder 26 and causes the piston 27 to move towards the

  left as shown in figure 2. Hydraulic pressure amplified

  fied in accordance with the ratio of the surfaces 28, 29 is therefore established in the pressure chamber 39. The limit pressure prevailing in the pressure limiting valves 31, 32 corresponds to the position of the

  stepped piston 27 which is transmitted by the piston rod 63 to the

  stroke control ports 33, 34. The more the stepped piston 27 is pushed

  dries forward, the higher the pressure at which the limiting valves

  31, 32 open to establish a connection with the tank

  see 14 is high. Consequently, the longer the stroke of the stepped piston 27

  the higher the pressure building up in the pressure chamber

  sion 39 is high. This limits the desired final stroke

pedal 11.

  The pressure determined by the pressure limiting valve

  sion-32, decreased in the pressure transmission ratio of the cylinder-

  dre stage 26 and the pressure drop at the anti-valve

  return 36 is then available at connection 41, that is to say

  say at the input of the amplification regulating valve 12. At this time

  The amplification regulating valve 12 determines, with a report

  identical transmission port, pressure at connection

  43, that is to say at its outlet, said pressure being applied

  to the piston-cylinder receiver assembly 15.

  As is evident from the above, it is par-

  It is particularly important for the present invention that the magnitude ratio of the surfaces 19, 23 of the amplification control valve 12 is identical to that of the surfaces 28, 29 of the volume receiver.

  25. In the practical case relating to a cylinder-transmitter-cylinder unit

  dre clutch receiver, this area ratio corresponds to the am-

desired fold.

  The non-return valves 36, 37, 38, which all open at around 0.5 bar, isolate the already described function of regulating

  the amplification of the pressure of that of regulation of the lowering

  ment of the pressure which will be described later. Since, in accordance with the present invention, the pressure limiting valves 31 and 32 are placed at the same pressure level and

  that a low pressure gradient is caused by the non-return valve

  turn 36, no volume can be lost through the limit valve

  pressure ration 32 because, thanks to the bypass point 35 located upstream of the non-return valve 36, the pressure limiting valve

  32 is set at a pressure slightly higher than the pressure e-

  xisting on connection 41 of the amplifier regulating valve

fication 12.

  Consequently, the regulation of the amplification of the pres-

  The amplification regulating valve 12 is therefore ensured by the pressure vessel at the pressure inlet of the stepped cylinder 26 from which the slight difference in pressure caused by

  the non-return valve 36. Ge pressure level is, meanwhile,

  controlled by the pressure limiting valve 32, the adjustment of which is determined by the position of the stepped piston 27 of the stepped cylinder 26. However, if the pressure in the piston-cylinder receiver assembly must be reduced, the pedal 11 is released, this which has the effect of returning the piston of the piston-cylinder transmitter assembly 16 under the effect of the return spring 58. This causes a reduction in pressure in the hydraulic line 59 which results in a return of the stepped piston 27 of the cylinder stepped 26. Therefore, the control force at the stroke control input 33 of the valve

  pressure limiting valve 31 decreases, as does the pressure at

  calf of the inlet of the amplification regulating valve 12, this pressure being lowered at the level of the reservoir by means of the connection 41, the hydraulic lines 66, 65, of the pressure limiting valve 31. Since the ball valve 21 of the

  amplification regulating valve 12 is open, the pressure decreases

  therefore also bare at connection 43 of the regulating valve

  amplifier 12. Part of the volume flows through the non-return valve and joins the stepped cylinder. The rest goes to

  through the amplification control valve. Through the valve an-

  ti-return 37 which opens, the pressure at the connection 43 of the amplification regulating valve 12 is applied to the

  pressure 39 of the stepped cylinder 26 and recalls the stepped piston 27 up to

  that balance is restored. Since the pressure of the amplification regulating valve, which is reduced by the pressure limiting valve 31, is further reduced by the pressure gradient existing at the non-return valve 37, no volume can be lost through the pressure limiting valve 32 because the latter is set too high for such a phenomenon to be

happen.

  The arrangement described therefore makes it possible to regulate with precision

  the amplification and the lowering of the pressure in the whole re-

  piston-cylinder sensor 15, even if a certain hysteresis occurs

  lu 2566062 resistance due to the pressure gradients of the non-return valves 36, 37, 38. The pressure limiting valves 31, 32 are valves

  more preloaded check valves with varying opening force

  connected by the stroke control inputs 33, 34 depending on the

  position of the stepped piston 27. Thanks to the use of non-return valves

  tower, the unit has a more compact design than the version in which accumulator springs act as a simulator

  race. It is possible to give the arrangement in accordance with the

  vention a configuration much more compact than a unit using accumulator springs because the springs can be smaller and easier to control while the actual racing simulation is ensured through an amplified transmission or, as the case may be, reduced . On a general level, the present invention therefore makes it possible to achieve a high degree of sensitivity and precision despite the substantial gains made in terms of space and

relief.

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Claims (12)

  1. Force amplification device equipped with a   sliding stroke generating element as a function of the force of   before being produced, an amplification regulating valve connected to   a pressure source of hydraulic pressure agent and a reservoir   see, said amplification regulating valve applying pressure   control sion, delivered by the pressure source, to a set   piston-cylinder receiver as a function of the stroke traveled by the stroke-generating element, characterized in that said valve   amplification regulator (12) comprises a cylinder (18) of confi   appropriate stepped guration containing a stepped piston-drawer. (17) which is biased towards its rest position by a return spring (22) and the smallest surface (23) of which is subjected to the   control pressure, this pressure being determined by the posi-   tion of said piston-drawer (17) inside said cylinder (18), and   in that said stroke generator element (11) applies a pressure   sion to a piston-cylinder emitter assembly (16) whose pressure is applied to the largest surface of said stepped drawer-piston (17), thereby allowing the latter to slide as a function of pressure   prevailing in said piston-cylinder transmitter assembly (16).   2. Force amplification apparatus according to claim 1, characterized in that said piston-drawer (17)   acts on two ball valves (20, 21) of which the first (21) is or   green when said stepped piston-drawer (17) is in the rest position and opens the connection between said piston-cylinder receiver assembly   (15) and said reservoir (14), and closes as soon as said piston   roir (17) leaves its rest position, and whose second ball valve (20) is located between said pressure source (13) and said piston-cylinder receiver assembly (15) and does not open until   said step piston-drawer (17) has closed said first bilge valve   the (21), the said second ball valve (20) closing again as soon as the force exerted by the control pressure on the said smallest surface (23) of the said stepped drawer-piston (17) and on the said return spring ( 22) is in equilibrium with the force exerted by the pressure   of entry on said larger surface (19).   3. Force amplification apparatus in accordance with   claim 2, characterized in that said two bilge valves   the (20, 21) are located parallel to each other at the bottom of said cylinder (18) opposite said smaller surface (23) of said stepped piston-drawer (17).   4. Force amplification apparatus in accordance with   any one of the preceding claims, characterized in   that a racing simulator (24) is placed parallel to said val-   ve amplification regulator (12).   5. A braking force amplification device according to claim 4, characterized in that said piston-cylinder transmitter assembly (16) applies pressure to a volume receiver   (25) absorbent: an additional volume of hydraulic pressure agent   that exactly represents the pressure produced by said assembly ble piston-cylinder transmitter (16).   6. Force amplification apparatus according to claim 5, characterized in that said volume receiver (25) comprises a stepped cylinder (26) integrating a stepped piston (27)   the largest surface (28) of which is subjected to the pressure of said   seems to be a piston-cylinder emitter (16) and the smallest area (29) and the displacement stroke of which act on a pressure-limiting valve device controlled by the stroke (30), so that the stroke traveled by said stepped piston (27) is converted into a pressure acting on said smaller surface (29) of the piston stepped (27).   7. A force amplifying apparatus according to claim 6, characterized in that said pressure limiting valve device (30) comprises a pressure limiting valve (32) which is subjected to the pressure of said - more small area (29) of said stepped piston (27) and is connected to said reservoir (14), and which has a controlled stroke control input (34)   by the stroke of said staged piston (27).   8. Braking force amplification device in accordance with 13 2566062   any one of claims 4 to 7, characterized in that a   non-return valve (36) opening in the event of overpressure in said assembly   seems piston-cylinder transmitter (16) is located between, on the one hand, the derivation (35) starting from said piston-cylinder transmitter assembly (16) and ending at said volume receiver (25) and, on the other hand,   said amplification regulating valve (12).   9. Force amplification apparatus in accordance with   any one of claims 6 to 8, characterized in that the-   said pressure limiting valve device (30) comprises a pressure limiting valve (31) which is subjected to the pressure existing at the inlet of said amplification regulating valve (12) and is connected to said reservoir (14) , and which has a stroke control input (33) controlled by the stroke of said stepped piston (27). 10. Force amplification apparatus in accordance with   claim 9, characterized in that the control pressure output   of said amplification regulating valve (12) is connected, through a non-return valve (37) opening in the event of overpressure at   said control pressure output, to the pressure chamber -   sion (39) of said stepped cylinder (26) which is subjected to the pressure   folded by said smaller surface (29).   11. Force amplification apparatus according to claim 9 or 10, characterized in that a non-return valve   (38) opening in the event of overpressure at the pressure inlet   of said pressure limiting valve (31) is installed   between, on the one hand, the pressure inlet of said limiting valve   pressure tion (31) subjected to the pressure applied by said piston   ton stepped (27) and, on the other hand, said piston-cy emitter assembly liner (16).   12. Force amplification apparatus in accordance with   any one of claims 8 to 11, characterized in that   said check valves (36, 37, 38) open for differentiation this pressure of about 0.5 bar.