FR2557646A1 - CONTROL FLUID CIRCUITS AND PILOT ACTUATED VALVES - Google Patents

Abstract

PILOT ACTUATED DIRECTIONAL CONTROL VALVE, INCLUDING A BODY ASSEMBLY WHICH HAS A BORE 24 PRESENTING PARTS OF LARGER AND SMALLER DIAMETERS, A DRAWER 48 THAT CAN SLIDE IN THE BALE, HOLES 62, 63 CONTROLS PROVIDED ON THE BODY ASSEMBLY AND CAPABLE OF SELECTIVELY ALIGNING WITH RADIAL PASSAGE MEANS 64, 65 OF THE DRAWER. IN THE BODY 18 IS PROVIDED AN INCORPORATED FLUID FILTER WHICH REDUCES THE RISK OF IMPURITIES PASSING INTO THE VALVE AND IN THE CORRESPONDING CIRCUITS WHICH CONTROL IT.

Description

FLUID CONTROL AND ACTUATED VALVES

BY PILOT.

  The present invention relates to improvements to fluid-controlled circuits and more particularly to control valves.

  directional fluid operated.

  Pilot operated directional valves and related equipment are used in dirty or hostile environments for other reasons and may be exposed to polluted fluids in systems where they operate. An example of such an environment is that of a commercial road truck. Compressed air systems of vehicles of this kind, used for brakes and

  for other assisted functions, may be fouled

  mud, water, oil and impurities

similar things.

  US Patent 3,215,163 describes a pilot operated directional control valve of a type usable in a gear change control system in the transmission of a truck

  commercial. When used in such an applica-

  tion, the pilot actuated valve responds to a remote valve located in the truck cab that is manually actuated by the driver. The reliability of these valves and the circuits connected to them can be adversely affected by impurities

  entering the corresponding circuits.

  The invention provides a pilot operated directional flow control valve with incorporated filtration means which reduces the risk of impurities passing through the valve and circuits

correspondents who order it.

  The filtration means is disposed inside the body of the directionally controlled valve, upstream of a distribution manifold also formed inside the valve body. As a result, the internal constituents

  of the valve themselves, as well as the valve and the components

  sants of circuits outside the envelope are protected by the filtration means. The filtration means comprises a hollow cylindrical filtration element housed in an associated cavity. The filter inlet has a sharp bend in the flow path, which

  tends to separate large particles from the flow stream

  Lement of fluid entering the filter and thus protects the filter against premature clogging. The geometry of the inlet, the filter and the distribution manifold also ensures mounting positions in which the inlet is placed lower than the filter, so that water and other polluting liquids, as well as solids, do not tend to rise in and clog the filter element. Normally the filtration capacity of the filter element is sufficient

  fine to stop water droplets.

  The filter element has the shape of a bowl

  overturned or from a cylinder with only one closed end.

  The open end of the filter element is pushed elastically against a seat by a spring of appropriate size. The spring has the desired dimension to release the filter element from its seat when there is a

  pressure difference predetermined on both sides.

  So, if the filter element gets dirty,

  the loss of pneumatic control does not immediately follow

  because air can avoid the element of

  filter when removed from its seat.

  The invention will now be described with reference to the accompanying drawings in which: FIG. 1 is a plan of a pilot operated directional control valve, constructed according to the invention; Figure 2 a side elevation of the valve of Figure 1; Figure 3 an axial view partially in section of the valve of Figure 1; Figure 4 a section of the valve of Figure 1, taken in a longitudinal plane, and Figure 5 a schematic fluid control circuit using the valve of Figure 1 according to

the invention.

  The drawings show a pilot operated directional control valve 10, described in more detail below, and a fluid control circuit 11 in which it is advantageously used. The control circuit 11 comprises, in addition to the valve 10, a source of compressed air in the form of an air compressor 12, an accumulator tank 13, a pneumatic actuating cylinder 14, a manually actuated valve 15 and pneumatic hoses connecting these components between

them.

  The valve 10 comprises a main body 18, an end block 19, a cylindrical cap 20 and a drawer assembly 21. The body 18 is formed of cast iron or other suitable material. The body 18 has a longitudinal bore 24 of staggered diameter, comprising a portion of smaller diameter 25 and a portion of larger diameter 26. The terminal block 19 has a cylindrical bore 27 which is coaxial with the bore 24 of the body and has a cross-sectional area preferably twice that of the smallest bore 25 in the body. The block

  terminal 19 is removably attached to the main body

pal 18 by screws 28.

  Near the blind end of the smallest bore 25 in the body is an inlet port 31 (Figure 3). This inlet port 31 is provided with a

  female thread for coupling to a feed pipe

  statement 32 (Figure 5). It will be understood that in service, the preferred orientation of the valve 10 corresponds to that of FIGS. 3 and 4 where it is shown drawn up. In this orientation, the bore 24 of the body is horizontal. When we speak here of the orientation of various elements of the valve, it is about this preferential orientation. The inlet 31 has a blind cylindrical bore 36 leading horizontally inside the body 18, starting from its threaded opening. A short vertical circular hole 37 provides communication between the inlet 36 and a larger cylindrical cavity 38. The hole 37 and the cavity 38 are coaxial and their axis is radial to the horizontal axis of the bore 36 of the orifice entry. A horizontal or manifold bore 39, perpendicular to the main bore 24 of the body, communicates with the cavity 38 and the inner end of the smaller diameter bore 25 of the body and forms an outlet 43 at its end opposite the cavity. The outlet 43 is provided with a female thread for the connection with a pipe 44 of the circuit 11. An optional outlet 45 is formed by an internally communicating threaded orifice

  with the outlet end of the manifold bore 39.

  In the body and the bores 24, 27 of the terminal block, is arranged a cylindrical slide 48 with a staggered diameter. Elastomer O-rings 49, 50 are provided in associated grooves, at the opposite ends of the drawer 48, to form tight sliding seals with the bores 25, 27. As can be seen in FIG. 4, the right end of all

  drawer 21 has an axial passage 53 which communicates

  that with a transverse bore 54 of the middle part

  from the drawer. A set of seals 57 disposed in the bore

  - transverse ge 54 includes a perforated sliding seal 58, a compression spring 59 and a pad 60. The sliding seal 58 and the pad 60 are provided with O-rings

  to seal the respective regions of Alésa-

  transverse ge 54. The spring 59 maintains an upper face

  of the sliding seal 58 against a lower face of the cylindrical cap 20. Depending on the axial position of the drawer assembly 21, the transverse bore 54 and the sliding seal 58 connect one of the two orifices 62, 63 of the cylindrical cap 20 at the drawer passage 53 and at the manifold 39. Two outlet orifices 64, 65 (FIG. 4) are designed to alternately ventilate respective orifices 62, 63, by the main bore 26 of the body and the games formed around the assembly of drawer 21 by respective grooves 67, 68. The control orifices 62, 63 are individually connected to

  working chambers of the jack 14, by pipes 69, 70.

  The manifold 39 is connected to the valve 15 by the pipe 44 and selectively, through this valve, to the cylindrical bore 27 of the control valve 10, by a pilot pipe 74. The valve 15 is a conventional unit with two positions three-way which plays the role of a master control valve of the directionally controlled valve or receiving valve 10, actuated by pilot. The valve 15 is manually operated by moving a control handle 76 to bring it closer

or move it away from its body.

  As shown particularly in Figure 3, a filter element 81 is disposed in the cylindrical cavity 38. Preferably, the filter element has the

  general shape of an inverted bowl. An eco-friendly form

  filter element 81 is a conventional pleated paper element, commercially accessible and normally used in liquid fuel pipes, for example in the automobile. At its lower peripheral face, the filter element 81 is housed in a base area 82 of the cavity 38. The interior of the filter element 81 is therefore in free communication with the vertical hole 37 to receive the current d incoming air passing through the inlet 31. The upper end of the filter element 81 is closed. The filter element 81 is resiliently held against the lower end or seat of the cavity 38 by a compression spring 83. The spring 83 has the size required to apply to the filter element 81 a predetermined vertical force directed towards the low. Cavity 38 is

  closed and the spring 83 is retained by a removable plug

  ble 84 screwed into the cavity. As shown, the plug 84 has the general shape of an inverted bowl and is provided with a generally cylindrical hollow skirt 85 which coaxially surrounds a substantial part of the filter element 81 so as to form a filtration zone which is contained in the main body, with a

  minimal increase in size or weight.

  It will be understood that in normal operation, the air arriving at the inlet orifice 31 will rotate and pass vertically through the circular hole 37, in the axial direction, towards the interior of the element of

  filter 81 and will then flow radially outward

  laughing through the pleated paper filter medium of the element. The air leaving the filter element 81 goes to the adjacent collector 39. The filter medium,

  designated by 86, has a relatively large pore size

  vely small, for example of the order of 5 microns.

  The control system described 10 applies to large road trucks. In this application, the actuator 14 can be mounted on the truck transmission to move it between the high and low speed ranges in response to changes in the position of the button 76 of the control valve 15 which can be mounted in the cab of the truck. The air compressor 12

2557646:

  and tank 13 can be the ones we use

  for the truck brake system.

  In the operation of the circuit 11, the valve being in the position of FIG. 4, the air pressure in the large bore 27 maintains the assembly of

  drawer 21 in the right position shown.

  The drawer assembly 21 is held in this position because the system pressure, coming from the reservoir and acting in this large bore 27, applies to the drawer a net force directed to the right. The drawer assembly 21 being in the right position, the air coming from the manifold 39 passes through the drawer passage 53, the transverse bore 54, the orifice 62, the pipe 69 and

  arrives at the respective working chamber of the jack 14.

  At the same time, the chamber on the opposite side of the piston

  of the jack 14 is ventilated by the pipe 70.

  When the control handle 76 of the manual valve or master valve is moved to its other position, the main bore 27 is emptied, allowing the drawer assembly 21 to move to the left relative to the position represented by the Figure 4, in response to the force generated by the system air pressure acting on the right end face of the drawer in the small bore 25. In this state, the system air pressure, prevailing in the manifold 39 , is led to the other port 63 by alignment

  of the transverse bore 54 on this orifice. Therefore

  quent, the cylinder 14 is caused to change position due to the inversion of the pressure conditions in the working chambers located on either side of the piston. As previously suggested, this change in position of the cylinder 14 is to perform work, by

  example to shift the range of transmission speeds

associated sion.

  From the foregoing discussion, one can understand

  dre that the filter element 81 is effective in protecting the interior working elements of the two valves 10, 15

  and the cylinder 14. The filter element 81, thanks to its poro-

  relatively small, is effective in stopping dust particles of any noticeable size, as well as oil or water droplets. In addition, the relative geometry of the region of the inlet 31 and the inverted filter 81 is particularly favorable for resisting premature fouling of the filter element. The right angle position of the inlet bore

  36 relative to the vertical hole 37 causes turbu-

  lence and a pulse variation so as to drop from the air stream any material in relatively large particles and to allow it to gather in the blind end of the bores 36. In addition, the spring 83 allows the element filter 81 to operate

  as a relief valve in case of premature fouling

  ture of the filter which could for example result from a failure of an oil seal of the compressor 12 which could introduce an excessive quantity of oil in parts of the circuit. More particularly, the spring 83 applies a vertical force to the filter element which takes account of a pressure drop of 34 kPa at La

  crossing of the filter 81. A greater pressure drop

  sion, due to the fouling of the filter 81, has the effect of overcoming the force of the spring 83, of removing from the seat 82 the lower end face of the filter, designated

  par 87, and avoid the filter element.

  It is understood that the particular embodiment described here is in no way limiting and many modifications and variations may be made by specialists, without departing either from the framework or the spirit

of the invention.

Claims (6)

  1. Fluid control circuit (11) including   with an actuated directional valve (10)   by pilot and a master control valve (15) used   before moving the directionally controlled valve, these two valves being at a distance from each other and connected by two fluid pipes, one of which is a pilot pipe directing towards the directionally controlled valve of the fluid coming from the valve mistress and received from the other   hose, the master valve being selectable   tively between two positions in one of which it applies fluid pressure to the pilot pipe while in the other it empties the pilot pipe, the directionally controlled valve comprising a body (18), an inlet and a manifold (39) placed in the body and communicating with the inlet, the second pipe mentioned being connected to the manifold and supplied by it, circuit characterized in that in the body of the directionally controlled valve, a filtration means (81) is interposed between the inlet and the manifold so that the filtration means is capable of filtering the fluid acting both in the directionally controlled valve and in the master valve control.   2. Pilot operated directional valve (10) comprising a body assembly which has a bore (24) having parts of larger and smaller diameters, a drawer (48) which can slide in the bore, controlled orifices (62, 63) provided on the body assembly and capable of being aligned selectively with radial passage means (64, 65) of the drawer in accordance with the axial position of the drawer in the bore, an inlet adjacent to a end of the body and associated with the smallest part of the bore, an outlet, a manifold (39) provided in the body and connecting the inlet both to the part of the smallest bore and to the outlet, a pilot orifice communicating with the part with the largest bore and designed to receive fluid coming from a remote valve and supplied by the outlet, valve characterized in that in the body (18) is arranged a filter (81) serving to filter the fluid received at the entrance before entering the collector, so that the filter is designed to protect the interior elements of the valve as well as a remote valve interposed between the outlet and the pilot orifice and to filter the outgoing fluid control ports.   3. Valve according to claim 2, characterized in that the filter (81) is resiliently retained against a seat formed in the body, by a spring element (83), the latter being constructed and arranged so as to allow the filter to move away from the seat when a determined pressure drop occurs   prior to crossing the filter element.   4. Valve according to claim 2, characterized in that the filter is provided in the form of a   bowl overturned and is placed above the entrance.   5. Valve according to claim 4, characterized   by the fact that the entrance includes a passage perpendicular   circular to a passage of the filter inlet.   6. Valve according to claim 5, characterized in that the passage leading to the inlet of the filter   is located along a vertical course.