FR2703702A1 - Road coating valve, spray bar fitted with such a valve and vehicle. - Google Patents

Abstract

The present invention relates to a valve assembly which can be used in a spray bar for spraying road plaster, comprising a housing (1) defining a chamber (2) having a fixed volume having an inlet (3) and an outlet (4). ) for the plaster, an elongated element (5, 6) which can move back and forth in the housing and which has, inside the chamber, a closing element (5) of the outlet brought into contact sealed with the outlet via a spring (9). The assembly is adapted to open the outlet by independent external action on the elongated element (5, 6) against the return, for example by means of a pneumatic device (10, 11, 12). The invention also relates to a spray bar having a plurality of valve assemblies and a spray vehicle having at least one spray bar, as well as a method for coating a surface.

Description

The present invention relates to a device intended to be used for

coat a surface, by

  example of roads and sidewalks, and its use.

  Coating a road involves spraying a liquid coating composition at a high temperature, for example around 2000 C, usually through a spray bar located

  on the rear of an adapted vehicle The coating, or the

  position forming binder, is applied through several valve assemblies Each must be able to act satisfactorily for a long period, under the given conditions, and it may be desirable to

  allow independent actuation of the valves.

  Figure 1 of the accompanying drawings shows a section of spray bar comprising a known valve assembly (in the closed position) In general terms, the assembly comprises a housing defining a

  chamber, an inlet and an outlet for the material li-

  which forms a coating, and an elongated element which can be

  move back and forth in the housing and that has an ele

  outlet closing ment which, due to a spring,

  is recalled in sealed contact with the outlet.

  The hydraulic pressure of the sprayed material

  helps the valve closing forces This can represent

  feel more than 50% of the force required to ensure

sealing the outlet.

  More specifically, the known assembly is adapted to open the outlet by pneumatic action (pressure drop) on the elongated element, against the reminder For this purpose, the chamber delimits the arrangement forming a cylinder of piston-cylinder assembly and

  the volume through which the binder moves is varied

corn.

  The existing system suffers from several

  Firstly, the plaster may leak into the pneumatic system Secondly, it may not fully open or close, thus causing a loss of flow Thirdly, its actuation is slow, resulting in starts and stops in stages between sets different located in a spray bar.

  The present invention is based on the appreciation

  the reasons for these problems and the supply

  a valve assembly which avoids their main causes

cipales.

  According to the present invention, in a valve assembly of the general type described above, the outlet closure element is located inside the

  bedroom The bedroom can have a fixed volume.

  quence, the opening of the exit against the adapted callback means implies an upward movement

  place of a downward movement of the elongated member.

  The known assembly is subject to the transport of ma-

  and a rupture of the piston o-ring

  dragging a binder leak into the tire system

  This can be avoided in a simple way.

  ment to the present invention, since the chamber and

  the pneumatic system are independent.

  In the known set, the return spring acts at the limits of its performance depending

  its length, and the length of the desired stroke.

  This leads to closure problems which arise.

  attempt in the form of excessive or staged surface finishes.

  The cause of these problems can be eliminated in a way

  simple by providing a longer spring.

  In the known assembly, the hydraulic pressure of the coating material acts against what is effectively a piston located inside the chamber. Consequently, the surface surface of the

  moving components in contact extends over the circumference

  rence of the piston The rupture of the O-ring and

  the resulting leakage are practically avoided, consistent-

  ment to the present invention, avoiding having a piss

  tone inside the chamber and by providing a surface surface of the moving parts in contact

much smaller.

  More specifically, a set of

  mant valve according to the present invention is of the valve stem type By providing an orifice independent of the chamber in which the binder is present and of any hydraulic device acting against the return to open the valve, venting can be supplied between the material section and the air system This prevents contamination of the pneumatic piping and valves Such an orifice also provides

  a convenient access point, for example for lubrication.

  A pneumatic opening device intended for the present invention may comprise, in the housing, another inlet for fluid, independent of the chamber and of any orifice as defined above,

  the fluid acting on a flange arranged on the element al-

  run along. The present invention will now be described, by way of example only, with reference to the accompanying drawings in which: FIG. 1 is a sectional view showing the prior art,

  Figure 2 is a sectional view of a set of

  ble forming a valve constituting an embodiment of

the present invention.

  As indicated above, Figure 1 of the

  attached sins represents the prior art and the

  The present invention will be described, by way of a single example.

  cally, with reference to Figure 2.

  it should be noted that the same reference numerals have been used in FIG. 2 as those used on

  Figure 1 when they indicate corresponding components

  heavy. Figure 2 shows a valve assembly as part of a spray bar 1 (torn off) The assembly includes a housing, for example of steel, defining a chamber 2 having an inlet 3 and an outlet 4 In the position shown , exit 4

  is closed by a head 5 screwed onto a valve stem 6.

  The correct closing preload can be adjusted, and

  the valve head 5 blocked on the rod 6, by means of

  diary of a grub screw 7 The valve head 5 has

  a steel body having a polytetra-

  fluoroethylene (PTFE) machined to give a bearing angle of 450 which corresponds to the outlet 4 The outlet 4 is

  arranged as part of an outlet 8.

  The valve head is returned in tight contact

  che with the outlet 4 via a spring 9.

  The length of the spring is sufficient to maintain a practically constant closing force. The hydraulic pressure of the coating material helps to ensure

  tightness due to the valve head.

  The valve stem can move back and forth

  comes inside the housing A sealing device

  tee located around the rod is arranged through

  for example a rafter seal with PTFE and to-

  usual risks of the "VITON" type (non-commercial filed).

  The valve stem has, at the level of the ex-

  opposite end to the valve head, an element 10 forming

  piston mounted inside another chamber 11 The box

  tier has another inlet 12 through which pressurized fluid (usually air)

  can be inserted to act against piston 10 and or-

  screw the valve against the return and pressure

  material hydraulics This other chamber It is inde-

  hanging from the chamber containing the material.

  The housing also has a separate orifice

  dant 13 This hole allows leakage of material

  mant coated to exit the set without reaching the

  pneumatic device and also provides access.

  The air port to the pneumatic cylinder

  is positioned so that additional fittings

  are not necessary The piston assembly and

  cylinder can be double acting if desired.

  A valve assembly of the type shown in FIG. 2 can be constructed in a simple manner,

  to be fitted in any spray bar

  that, for example of the type used with a valve assembly of the type shown in Figure 1 It can provide reliable service A prototype assembly has been tested under operating conditions for 60,000 cycles

  (representing about six years of work) without

  no problem Forty-eight other sets provided reliable contract service for a continuous period that began after the priority date of this application.

Claims (6)

  1 valve assembly comprising a housing defining a chamber (2) comprising an inlet (3) and an outlet (4) for a liquid, an elongated element (5, 6) which can move back and forth in the housing and which comprises an element (5) for closing the outlet, recalled in sealed contact with the outlet (4), the assembly   being adapted to open the outlet (4) by external action   higher on the elongated element against the return,   characterized in that the chamber (2) has a fixed volume and the closing element (5) is located inside the chamber.   2 Valve assembly according to the claim   tion 1, characterized in that it independently of the chamber (2), a cylinder (11) and another inlet   (12) for a fluid, and in that the elongated element sup-   carries a piston (10) located inside the cylinder (11)   and on which the fluid can act in order to open the outlet tie.   3 Valve assembly according to the claim   tion 2, characterized in that it comprises an orifice (13) going up to the elongated element (5, 6), independent of   the chamber (2) and located between the chamber (2) and the cylinder dre (11).   4 Spray bar with several   valve assemblies according to any one of the res-   previous indications, characterized in that the inputs   respective rooms are in communication with the inside the bar.   5 spraying vehicle comprising a spraying bar according to claim 4 and means for controlling the opening of the outlets (4) of the respective rooms.   6 Method for coating a surface, characteristic   se in that it consists in applying the coating via a   spray bar according to claim 4.