FR2555700A1 - PRESSURE VALVE - Google Patents

Abstract

PRESSURE VALVE INCLUDING A CLOSING ELEMENT 8 SUBJECT TO TENSION AND DESIGNED TO BE PRESSED AGAINST A VALVE SEAT 7. WHEN THE PRESSURE APPLIED ON THE INLET SIDE OF PRESSURE VALVE 1 IS SIGNIFICANTLY LOWER THAN THE RATED RESPONSE PRESSURE, THE ELEMENT CLOSURE 8 IS BROUGHT INTO CONTACT WITH THE VALVE SEAT 7 BY A FORCE SIGNIFICANTLY GREATER THAN THE VOLTAGE CORRESPONDING TO THE NOMINAL RESPONSE PRESSURE, WHILE, WHEN THE NOMINAL RESPONSE PRESSURE IS APPLIED ON THE INLET SIDE OF THE COMPRESSION VALVE 1, A FORCE ADAPTED TO THE NOMINAL RESPONSE PRESSURE IS APPLIED TO THE CLOSING ELEMENT 8. THE INVENTION IS APPLICABLE IN BRAKING CIRCUITS OF MOTOR VEHICLES.

Description

The present invention relates to a pressure valve

  having a closure element under tension and

  designed to be pressed against a valve seat.

  In pressure valves of this type, the closure elements are often hardened steel balls. These steel balls can be manufactured cheaply, mass-produced and with high precision. Compared to valves with guided trays

  stems, the above pressure valves are characterized by

  simpler construction in that the balls, which automatically position themselves on the seat of the valve under

  the effect of a pressure force, do not need to be

  important guiding elements.

  Although the metal closure elements allow

  to obtain sealed valves without even having to use

  elastomeric sealing membranes; hard particles of impurity

  may cause scratches on the seat

valves and therefore leaks.

  In pressure relief or overpressure valves

  equipped with balls, the force which is exerted on the ball and which opposes the pressure of the fluid depends, according to a quadratic ratio,

  the diameter of the ball. This force is distributed along a line

  which increases in a linear relationship with the dia-

  meter of the ball. The closing force therefore drops rapidly when

  that the size of the valve decreases. It often happens that the closing force is no longer sufficient to drive out the smallest impurities. However, it is essential that the tightness of the system

  be assured at any time of the operation. We have already proposed

  to provide a fine filter upstream of the valve. fouling

  of the filter neutralizes the action of the pressure

  which may have undesirable consequences when the

  pope is used as a pressure limiting device or as

booster.

  DE-PS 26 11 216 discloses a pressure relief valve

  The invention is characterized in that it comprises a plate which is connected by a spring to a piston which slides in a guide body against the force of the spring when it is subjected to the action of a pressure medium. The position of the piston in the guide body determines the level of

  the opening pressure of the valve.

  DE-OS 18 13 167 discloses a valve

  pressure device comprising on the one hand a closure element

  in the opposite direction to the direction of flow of the pressure medium and on the other hand a control piston secured to the iron element.

  by a lever device. This type of overflow valve

  sion comprises a pilot piston on which the pressure difference between high and low pressure is applied. Thanks to the pilot piston, the transmission ratio of the lever device is modified to

  cause the closure element to open.

  The objective of the present invention is therefore to propose

  a pressure valve of the type indicated above, the sealing of which

  It is assured despite the impurities present in the agent of pres-

  and even in the absence of a filter.

  The objective - according to the present invention is achieved in that, at a pressure much lower than the nominal pressure

  of response exerted on the admission of the pressure valve, the

  the closure element is pushed against the seat of the valve under

  the action of a force substantially exceeds the voltage corresponding to

  the nominal pressure of response and that, at a pressure

  nominal response response on the inlet side of the

  pressure, the closure element is subjected to a force adapted to the

  Rated pressure response. The seal is therefore much better

  due to the very high pressure exerted temporarily on the seat of the valve and which is then reduced to the nominal value of the valve. Due to the very strong pressure exerted

  on the sealing surfaces impurities are displaced or simply

forced into the passage.

  According to an advantageous embodiment according to

  In accordance with the invention, it is provided that the closure element is subjected to the tension of a spring by means of a pusher and

  that the end of the spring opposite the pusher moves, as a function of

  the pressure exerted on the intake side of the compression valve

  between a first extreme position for which the im-

  placed on the closure element is at its maximum and a second

  extreme position for which the force exerted by the spring on the closing element is equal to the force generated by the pressure

nominal response.

  An embodiment example of a particularly simple design

  According to the invention, the end of the spring opposite the closing element is in contact with a pilot piston whose working surface is subjected to the action of an active agent under the pressure prevailing on the admission side. of the pressure valve and which is subjected to a voltage greater than the force of the spring on the closure element at nominal pressure response.

  In accordance with another embodiment of the invention,

  the cylindrical and hollow pilot piston, slidably mounted in a

  cylinder, houses the valve seat, the closure element, the push-

  evening and the spring surrounding said pusher, while at the bottom of the pilot piston are provided orifices for the passage of the active agent that can be evacuated by a cavity not subject to the

  pressure of the active agent and through a passage opening of the cylinder.

  This type of embodiment is compact in design and does not include any complex execution part. The whole can be

manufactured cheaply.

  Preferably, the workspace reserved for the active agent

  is located between an annular flange of the pilot piston, the wall

  cylinder and a cover closing said cylinder in its

  beforehand, said cover having an axial intake duct formed in a cylindrical body which is executed in the form

  of an inner guide piece for the pilot piston and which includes

  ducts connecting the intake duct and the work space. This device consists essentially of

  symmetrical parts of revolution easy to achieve.

  Preferably, the voltage applied to the pilot piston by the spring is calculated so that the displacement of said pilot piston

  starts at about 95% of the nominal pressure response.

  In an example of practical application, the pressure valve is located parallel to a control valve and

  a device for actuating a braking circuit of a vehicle

the automobile.

  The compression valve of the invention is preferably a seat valve whose closure element can be a ball,

a cone or a valve plate.

  The different objects and characteristics of the invention

  will now be detailed in the description that follows, made

  by way of non-limiting example, with reference to the appended figures which represent: FIG. 1, a longitudinal section of a pressure valve implanted on the hydraulic braking circuit of a motor vehicle, said circuit being represented in schematic form,

  FIG. 2, a diagram of the pressure force of the

  the closing element on the seat of the valve and the stroke of the

  pilot piston with respect to the pressure exerted on the input side.

  The pressure relief valve 1 as shown in the figure is a seat valve having a cylinder 2 whose face

  front open is provided with a circular flange 3. The flange 3 re-

  a lid 4 provided at its center with a cylindrical body extending

  in the axial direction 5. The cylindrical body 5 protrudes from

  on the other side of the lid 4. On the part of the cylindrical body

  5 outside the cylinder 2 is provided with a thread (no

  represented in detailed form). The cylindrical body 5 is traversed

  se by a concentric conduit 6 whose end opening into the cylinder 2 forms a seat 7 for a hardened steel ball

  8, a pusher 9 acting on the side of said ball opposite the seat

  7. At the end 10 resting on the ball 8, the push

  evening 9 has the shape of a plateau. The end of the spring 12 which surrounds

  re the pusher 9 is in contact with the plate end 10 of the pusher 9, said spring being under tension while

  its other end rests on a circular wall 11. The circular wall

  11 through which the lights 13 is part of the bottom of the pis-

  cylindrical and hollow pilot 14 which surrounds the spring 12, the pusher 9, the ball 8 and the part of the cylindrical body 5 penetrating into the cylinder 2. Said part forms a guide surface for the cylindrical and hollow pilot piston 14 whose face front open is surrounded by an annular flange 15. A spring 16 bears on the rim 15 while the other end of said spring comes into

stop on the bottom of the cylinder 2.

  The working space reserved for the hollow cylindrical piston 14

  is between the rim 15 and the lid 4. On the face of the neck

  4 are turned towards the cylinder 2 and are provided with recesses 17 which communicate via conduits 18 with the central duct 6 of the

cylindrical body 5.

  In the wall of the annular flange 15 is provided a seal 19

  for thermally isolating the space at which the active agent is

  20, receiving the spring 16. An outlet orifice 21 is formed in the bottom of the cylinder 2. Another seal 22 is placed in the outer wall of the cylindrical body 5 which rests on the pilot piston 14. The role of the seal 22 is to prevent the agent

  asset does not move from the workspace into the space housing the

The 8th.

  The duct 6 is connected to a pressure source 23 which pre-

  lifts the active agent onto a feed tank 24 to which the

  outlet 21 is connected via a pipe 25.

  the compression valve 1 is provided with a circuit

  operates a control valve 26 and a regulating member 27.

  The pressure valve 1 serves as a limiting valve

  pressure and, thanks to the tension of the spring 12, can be set to a predetermined response nominal value. The force corresponding to the nominal pressure of response is exerted by the spring 12 on the ball 8 if the pilot piston 14 is in abutment against the bottom of the cylinder 2. The tension of the spring 12 in this

  position determines the nominal pressure response.

  When the pilot piston 14 is in the position indicated in FIG. 1, the spring 12 is considerably more compressed than with

  the nominal pressure of response. A pressure force is therefore trans-

  ball 8 to the valve seat 7, said force being clearly

  above the nominal response pressure. -

  Due to the tension of the spring 16, the pilot piston 14 is held in the position shown in FIG.

  applied pressure on the inlet of the ball valve 1, i.e.

  say in line 6, fell below an adjusted limit

  corn. This limit is determined by the tension of the spring 16.

  It has been found that it is advantageous for the spring 16 to exert

  this on the pilot piston 14 a force corresponding to 95 Z of the pres-

  nominal response. The pilot piston 14 remains in the rest position as long as the pressure inside the duct 6 has not reached the tension due to the spring 16. As soon as this force exceeds this threshold value, the piston 14 moves towards the bottom of the cylinder

  2. As the pressure increases inside duct 6, the pis-

  14, subjected to the action of the active agent on the flange 15, tends more and more to leave its initial extreme position shown in FIG.

  Figure 1 and coming into contact with the bottom of the cylinder 2.

  When the pilot piston 14 is in this second extreme position, a force corresponding to the nominal pressure of response

  is applied to the ball. The pressure exerted on the 8 corres-

  then lays at the antagonistic force coming from the pressure of the agent

  active. When the pressure increases very slightly, the ball 8 or-

  duct 6 and the active agent flows back to the feed tank.

  24 through the openings 13, 21 and the pipe 25,

  thus avoiding any further increase in pressure in the cir-

baked hydraulic.

  If, as can happen when the regulator

  27 is actuated, the pressure inside the duct 6 falls into

  under 95% of the nominal pressure response, the pressure force

  on the valve seat 7 undergoes a higher elevation. Under the ef-

  such a large pressure force, any

  are removed from the valve seat or simply to

  through it, cleaning the sealing surfaces as they pass.

  The sealing action of the ball valve 1 is therefore maintained,

  even if the active agent contains impurities.

  FIG. 2 shows the stroke 28 of the pilot piston 14 as a function of

  pressure is inside the duct 6. The stroke is on the ordinate and the pressure on the abscissa. Figure 2 also illustrates the

  pressure force 29 of the ball 8 exerted by the spring 12 as a function

  The force exerted by the pressure is also represented as a function of the pressure inside the conduit 6. At the point of intersection of the curves 29 and the resultant force applied to the the ball 8 is equal to zero in

  the measure where the forces 29 and 30 are equal and where they are di-

rectionsopposées.

  It is obvious that the foregoing descriptions have

  given as a non-limitative example and that many variants can be envisaged without departing from the scope

of the invention.

Claims (9)

  1. Pressure valve having a closure element   re subject to tension and designed to be pressed against a seat   valve, characterized in that when the applied pressure   the admission of the pressure valve (1) is markedly inferior to   the nominal pressure of response, the closure element (8) is   brought into contact with the valve seat (7) by a markedly   than the voltage corresponding to the rated pressure of   response, and that when the nominal response pressure is   When applied to the pressure relief valve (1), a force adapted to the nominal pressure of response is applied to the element closing (8).   Pressure valve according to claim 1,   characterized in that the tension of a spring is applied to the element   closing member (8) by a pusher (9) and that the end of the spring (12) opposite the closure element (8) moves, in   depending on the pressure exerted on the intake side of the   pressure (1), between a first extreme position for which the force imposed on the closure element (8) is at its maximum and a   second extreme position for which the force exerted by the res-   fate (12) on the closing element (8) is equal to the force generated   by the nominal pressure of response.   Pressure valve according to claim 1 or   2, characterized in that the end of the spring (12) opposite to the   the closing element (8) abuts against a pilot piston (14) at   the working surface from which the active agent is applied under the   on the inlet side of the pressure valve (1), said piston being subjected to the tension of a spring which exceeds the force exerted by the spring (12) on the closure element (8) in the   case of the nominal pressure of response.   4. Pressure valve according to one of the claims   characterized in that the hollow and cylindrical pilot piston (14) slidably mounted in a cylinder (2) comprises the valve seat (7), the closure element (8), the pusher (9) and the spring (12) surrounding the pusher (9), and in that at the bottom of the   pilot piston (14) are made lights (13) ensuring the pas-   wise of the active agent that can be evacuated by a cavity (20) not subjected to the pressure of the active agent and by an outlet (21) of the cylinder (2)   5. Pressure valve according to one of the claims   previous arrangements, characterized in that the work space   active agent is made between an annular flange (15) of the piston   your pilot (14), the inner wall of the cylinder (2) and a cover (4) closing the cylinder in its front portion (2), said cover (4) being traversed by an axial intake duct (6) formed in a cylindrical body (5) acting as an internal guide for the pilot piston (14) and comprising conduits (18) connecting   the internal duct (6) and the working space.   6. Pressure valve according to one of the claims   tions, characterized in that the voltage applied to the   pilot piston (14) by the spring (16) is calculated so that the   The placement of the pilot piston (14) starts at about 95% of the pressure. nominal response.   Pressure valve according to one of the claims   tions, characterized in that it is implemented in parallel   to a control valve (26) and an actuating mechanism   (27) placed on the brake system of a motor vehicle.   8. Pressure valve according to one of the claims   tions, characterized in that the compression valve is a seat valve.   9. Pressure valve according to one of the claims   previous arrangements, characterized in that the closure element is   a ball (8), a cone or a valve plate.