FR2520060A1 - STARTING CONTROL DEVICE FOR HELICAL COMPRESSORS - Google Patents

Abstract

IN THIS START-UP CONTROL DEVICE FOR HELICOIDAL COMPRESSORS 1 WHOSE DISCHARGE FLOW IS ADJUSTED BY AN ADJUSTING VALVE 4 INTERCATED IN THE SUCTION DUCT 2, ADJUSTING VALVE 4 IS OPERATED BY A REGULATOR 5 REQUESTED BY THE FLUID PRESSURE DELIVERED BY THE COMPRESSOR 1. IN A DUCT 10 WHICH AVOIDS THE VALVE 4 IS INTERCALED A CONTROL VALVE 11 WHICH THE SHUTTER IS RELEASED TO OPEN BY A SPRING 12 AND TO CLOSE BY THE PRESSURIZED FLUID DELIVERED BY THE COMPRESSOR 1. IN THE ZERO PRESSURE INSTALLATION, VALVE 11 IS THEREFORE OPEN TO ALLOW THE COMPRESSOR TO GENERATE PRESSURE ON START-UP, EVEN WHEN THE ADJUSTMENT VALVE 4 IS CLOSED. THIS PRESSURE CLOSES VALVE 11 TO ALLOW NORMAL REGULATION.

Description

The invention relates to a device for

  starting command for helical compressors, the discharge rate of which can be regulated by an adjustment valve interposed in the suction line and which is operated by means of a regulating device which activates

  operated by the pressurized fluid discharged by the compressor

  a control valve being mounted in bypass

  relative to the adjustment valve.

  When the regulation of the discharge flow of the axial compressors is ensured by means of an adjustment valve mounted in the suction line, it is necessary to keep the adjustment valve closed

  during compressor start-up to avoid over-

  sudden load of the compression system and, in

  particular, of the drive motor However, the van-

  adjustment valve must open immediately after switching on

  che so that he can build up a pressure that is born

  necessary, in particular, for the injection of the oil Or, this operation of the adjustment valve requires the existence of a certain minimum pressure which is not available in the compressed fluid network at the time of the first setting in operation of the compressor installation either

only after a prolonged stop.

  It is already known to start, before starting the helical compressor, a small control air compressor, for example a piston compressor

  which establishes the minimum pressure necessary for the action-

  However, these relative costs

  important are only justified in the case of large

  compression installations Furthermore, it is known to provide an electrovalve mounted as a bypass by

  compared to the adjustment valve and which opens during the

  the axial compressor works and closes after the

  In this case, provision must be made for the order of

  the solenoid valve of electrical devices which not only

  increase the cost of installing the

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  compression but can also affect operational safety. The object of the invention is to describe a simple device for controlling the starting of the helical compressors which is actuated exclusively by pneumatic means and ensures the rapid establishment of a pressure in the compression installation without using any fluid under

external pressure.

  The invention solves this problem by the fact that the shutter member of the control valve is provided with a spring acting in the opening direction and is biased in the closing direction by the pressurized fluid discharged by the compressor With this device, the control valve placed in bypass with respect to the control valve is open when the installation of

  compression is under zero pressure so that there

  te a small free suction section which allows the

  immediate release of a pressure when the compressor starts As soon as the pressure has reached a level sufficient for actuation of the control valve, the control valve closes, after which the regulation of the

  pumped flow is ensured by the adjustment valve.

  poqitif according to the invention -is therefore characterized by a particularly great simplicity, since it does not include

  not the use of electrical devices or a

  additional control air pressure.

  The control valve can be a pneumatically operated two-way valve which is actuated by means of a pressure regulator actuated by

  the final pressure of the compressor The pressure regulator

  The only function of the valve is to close the control valve and keep it closed as soon as there is enough pressure in the compression system to actuate the control valve.

  adopt a simple embodiment for this regulation

tor.

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  However, according to the invention, it is also

  advantageously possible to provide a control valve

  of direct action which simultaneously ensures the function

  of the two-way valve A simple form of realization

  tion of this kind consists in the fact that the valve of

  control has a membrane that controls the passage

  sant in bypass with respect to the regulating valve Here, the diaphragm is stressed by the pressure prevailing in the compression installation. At the state of zero pressure, it frees the passage of the fluid in the channel while, when it is stressed by pressure, it closes the conduit. A spring acting in the direction of opening can be provided, the elastic force of which is chosen by

  depending on the desired closing pressure.

  In another embodiment of the in-

  Note, the control valve includes a sliding piston

  sant which can move in translation in a bore

  of cylinder and which controls the conduit passing in diversion

  relative to the control valve This valve

  command is made up of a small number of elements which

  can be manufactured in a simple way To keep the bypass channel open when the installation of

  compression is under zero pressure, it is advantageous-

  Here, too, a spring acts on the piston.

  your sliding in the direction of opening.

  In another embodiment of the in-

  Note, the control valve can be incorporated in the case or in the shutter member of the adjustment valve, for example in a sliding shutter or

  shutter type In this case, we do not have to provide for the

  positive start command according to the invention none

  device outside the control valve and the lines

  the additional link tests are also deleted.

  Other features and advantages of the

  vention will be better understood on reading the description

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  tion which will follow from an exemplary embodiment and with reference to the accompanying drawings in which,

  Figure i is a block diagram of an ins-

  compression plant which is provided with a starting control device according to the invention; Figures 2, 3 and 4 show three different variants of the device according to the invention which are incorporated in the adjustment valve of the helical compressor, the device being illustrated in each case by an axial median section of the shutter member of the

adjustment valve.

  The compression installation shown in FIG. 1 is composed of a helical compressor 1 provided with a suction line 2 and a

  discharge 3 In the suction line 2, is inter-

  a regulating valve 4 which is controlled by a device

  positive regulator, which is solicited, through

  diary of a regulation line 6, by the pressure of the

  compressed fluid prevailing in the discharge line

  ment 3 Downstream of the compressor i is interposed, in the discharge line 3, an oil tank 7 o

  leaves an oil injection line which returns to the

  helical presser 1 It is also provided in the con-

  delivery line 3, a pressure check valve

  Zion made in the form of a non-return valve For controlling the start of the helical compressor 1, there is provided a control valve 11 interposed in a

  bypass duct 10 which avoids or bypasses the re-valve

  glage 4 and whose shutter member is biased in the 'direction of opening by a spring 12 and, in the direction of

  closing, by the compressed fluid discharged by the compress-

  sor, via a control line 1 i-

  which is stuck on the discharge line 3.

  Figure 2 shows a part of the suction line 2 in which the adjustment valve 4 is interposed This valve is here constituted by a flap which can pivot around a control rod 14 mounted

  in the suction line 2 and which constitutes its axis.

  The bypass line 10 is composed of two holes

  approximately radial, provided in the wall of the suction pipe 2 on either side of the regulating valve 4 As control valve 11, a

  membrane 15 which covers the holes in the discharge duct

  rivation 10 and is fixed to the suction pipe 2 by a cap 16, which is provided with a connector 17 for the connection of the control pipe 13 The spring 12 loads the membrane 15 in the direction of opening of

the control valve 11.

  In the embodiment shown in Figure 3, the control valve It is interposed

  in the control rod 14 of the adjustment valve 4.

  In this control rod 14 is provided a cy-

  lindrique axial 18 in which can slide a sliding piston 19 which controls the bypass duct 10 formed by a transverse drilling The spring 12 maintains

  the sliding piston 19 in the open position shown

  shown in Figure 3 For the delivery of the

  control, there is a fitting 17 at the end

  outside of the cylindrical bore 18.

  FIG. 4 shows a variant in which the adjustment valve 4 has a shutter member 41 mounted to slide in a valve box 20 The shutter member 21 adjusts the section of the suction line 2 which passes through through the valve housing The control valve is here mounted in the shutter member 21 of the adjustment valve 4 and it is constituted, as in the embodiment

  in Figure 3, by a sliding piston 19 which can

  smooth in a cylindrical bore 18 There is provided, as a bypass duct 10, a transverse bore formed in the shutter member 21 The connector 17 provided at the end of the cylindrical bore 18 is used to connect

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  the control line 13 and the spring 12 which acts on the sliding piston 19 keeps the control valve 19 open when the control pressure fails. The mode of action of the device described is as follows:

  front: when starting the helical compressor 1 re-

  presented in FIG. 1, the adjustment valve 4 is firstly closed When the compression installation is at zero pressure, for example during the first setting up

  on, or after a long stop time, the regulating valve

  ge 4 cannot be opened because the operating pressure acting on the regulating device 5 and which

  is necessary for this opening is lacking The sou-

  control pope 11 is on the contrary kept open by the spring 12, since at the beginning, it does not receive pressure by the control pipe 13 The helical compressor 1 can therefore suck the fluid through the pipe

  bypass 10 so that it settles relatively relatively

  a pressure in the oil tank 7 Le

  pressure retaining valve 9 transmits this increase

  pressure injection Oil injection therefore also controls

  immediately under this effect, via line 8, so that any damage to the compressor is thus avoided

  helical default lubrication As soon as the pressure

  Zion has reached a value sufficient for actuation of the control valve 4, the control valve 11 closes, after which the flow control of the helical compressor 1 is ensured by the operation of the control valve 4 controlled by the regulating device 5, which is stressed by the pressure prevailing in the discharge line 3, via the gulation line 6 When, after the compression installation has stopped, the discharge line 3 is under pressure

  zero, the regulating device 5 closes the check valve

  Glage 4 Since the pressure of the control 13

  also cancels, the spring 12 opens the control valve

  command 11 and it therefore opens the bypass duct

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  tion 10, so that the compression plant is

  now ready for a new start-up operation.

  In the example embodiments shown on

  Figures 2, 3 and 4, actuation of the control valve

  demand occurs directly under the action of the pressurized fluid sent through the control line 13 and by

  through the fitting 17 In the embodiment

  tion of Figure 2, this pressurized fluid acts on the membrane 15, so that, when the value of the pressure supplied is sufficient, this membrane is applied

  on the drill holes which form the discharge duct

  rivation 10, by overcoming the force of the spring 12 As soon as the pressure is canceled in the control line 13, the

  spring 12 again lifts the membrane 15 from the holes.

  In the embodiments according to FIGS. 3 and 4, the control pressure conveyed by the fitting 17 acts on the sliding piston 19 which, here too, closes the bypass duct 10 by overcoming the force of the spring 12, in the presence of a sufficient value for the pressure supplied In place of this direct actuation of

  control valve 16, however, it is also

  It is possible to provide a simple two-way valve as the control valve and to actuate this valve by means of a pressure regulator, which can also be of simple construction. The control line 13 provided in FIG. 1 would then lead to a regulator

  pressure In all the exemplary embodiments, the provision

  according to the invention guarantees that at the time of

  swirl of the helical compressor, it is established without

  late enough pressure for actuation of the

adjustment valve.

  Of course, various modifications may be made by a person skilled in the art to the device which has just been described only by way of example without leaving

of the scope of the invention.

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Claims (4)

  1 Start control device for helical compressors whose discharge flow can   be adjusted by an adjustment valve inserted in the con-   suction tube and which can be operated by means of a regulating device, which can be actuated by   a pressurized fluid discharged by the compressor, however   as long as a bypass control valve is provided   relative to the adjustment valve, this device being   characterized in that the shutter member of the control valve (11) is provided with a spring which acts in the direction   opening and is pressed in the direction of closing-   ture by the pressurized fluid discharged by the compress- sister.   2 Device according to claim 1, charac-   characterized in that the control valve (11) is a   pneumatically controlled two-way pope, which is action-   born via a ground pressure regulator   allowed by the compressor outlet pressure (1).   3 Device according to claim 1, charac-   characterized in that the control valve (1) comprises a   membrane (15) which controls a conduit disposed in a derivative   relative to the adjustment valve (4).   4 Device according to claim 1, charac-   in that the control valve (11) includes a   sliding piston (18) which can move in transla-   tion in a cylinder bore (18) and controls a con-   duit disposed as a bypass with respect to the re-valve glage (4).   Device according to any one of Claims 1 to 4, characterized in that the shut-off valve   control (11) is mounted in a housing (20) or in the   shutter valve (21) of the regulating valve (4), for example   ple, in a sliding or pivoting shutter member the adjustment valve.