FR2522737A1 - SUCTION ADJUSTMENT VALVE FOR ROTARY COMPRESSORS - Google Patents

Abstract

THIS SUCTION ADJUSTMENT VALVE 3 FOR ROTARY COMPRESSORS 2, ESPECIALLY FOR OIL-INJECTED HELICAL COMPRESSORS, IS OF THE TYPE WHICH INCLUDES A SHUTTER ELEMENT 11 WHICH CONTROLS THE SUCTION LINE 12, AND A CONTROL PISTON 18 WHICH CAN BE MOVED BY A PRESSURIZED FLUID, UNDER THE ACTION OF A REGULATOR 8, AGAINST THE FORCE OF AN ADJUSTING SPRING 19 AND ACTS ON THE CLOSING ELEMENT 11 OF THE VALVE 3 IN THE DIRECTION OF CLOSING. HERE, THE SHUTTER ELEMENT 11 IS SOLICITED BY A NON-RETURN VALVE SPRING 13 INDEPENDENT OF THE CONTROL PISTON 8. THIS VALVE FORM A NON-RETURN VALVE WHICH CLOSES THE SUCTION PIPE 12 BEFORE STARTING THE COMPRESSOR AND IMMEDIATELY AFTER SHUTDOWN OF THIS ONE. A RETAINING ELECTRO-MAGNET 14 ALLOWS DELAYING THE OPENING OF THE SHUTTER ELEMENT 11 TO GIVE A START OF THE COMPRESSOR WITH DECOMPRESSION.

Description

The present invention relates to a soupa-

  eg suction adjustment for rotary compressors, especially for oil-injected helical compressors, this valve comprising a shutter element which controls the suction line, is elastically biased in the closing direction, and can be

  moved in the closing direction by a piston

  command guided in a cylinder and biased by a spring

adjustment.

  We already know from DE-OS 2 944 053,

  a suction control valve, the element of which

  turator resiliently biased in the direction of iron-

  meture is connected to the control piston which is biased in the direction of opening by the operating pressure produced by the compressor To stop the discharge or perform flow regulation, the pressure prevailing in the network supplied by the compressor can also act in the closing direction on another pressure surface of the control piston, which is larger than

  the pressure surface stressed by the service pressure

  vice Here, when the compressor starts, the con-

  suction line - is opened as soon as a

  certain pressure Closing the suction line

  tion after the compressor has stopped is ensured by the

  comes out and by the network pressure that still exists in

  the reservoir, as soon as the operating pressure of the compressor

  sor has fallen The opening and closing of the pipe

  te suction are therefore controlled according to the

  pressure of the pressurized fluid discharged by the compressor

  Here it is not guaranteed that the vacuum line

  ration will be closed immediately after the compressor stops,

  so that an additional air reflux can occur

  born of oil in the suction line It is therefore most often essential, for safety reasons, to provide in addition in the suction line

  a non-return valve special to this line

  their relatively complicated construction of the device

  known tif is a drawback.

  The invention aims to improve the valves

  d.e aspiration adjustment known so far from ma-

  to guarantee a decompression start when the compressor is started and so that, when the compressor stops, the suction line is immediately closed without the need for a special valve anti-return in this

conduct.

  According to the invention, this problem is solved by

  the fact that the shutter element formed separately from the

  control tone is solicited by a check valve spring

  its own return valve provided with a retaining device, preferably a retaining electromagnet

  electrically operated, by means of which it can be hand-

  held in the closed position The suction control valve according to the invention therefore acts both when switching on and when switching off.

  compressor, like a specially pre-check valve

  seen in the pipe, without being obstructed by the piston

  The spring of the non-return valve may be weak

  accordingly, so that the suction pressure pro-

  supplied by the compressor at the time of switching on is sufficient for opening. By means of the retaining device, it is possible to choose in a simple and

  specifies the desired delay time with which the

  suction line is open to ensure start-up

  in decompression When the compressor stops, the

  suction hose is immediately closed so that it does not

  reflux of an additive compressed fluid cannot occur

  oil actuated The control piston makes it possible to obtain a simple adjustment of the delivery rate in combination with the obturating element. Another advantage consists in the simplicity of the construction of the suction adjustment valve according to the invention and in simple form

  of the components of this valve.

  According to another characteristic, there may be associated with the shutter element a stop which limits the opening stroke of this element and which can be adjusted by the control piston In this way, the suction section released by the element shutter can be adjusted by continuous variation for the adjustment of the discharge flow In the same way, it is possible to completely close the suction adjustment valve by means of

of the control piston.

  The control piston is preferably stressed

  cited in the direction of opening by the regulation spring

  ge and in the closing direction of the shutter element

  by control pressure Can be used for ac-

  actuation of the control piston a pressure regulator

  positive, the control line of which does not

  control sion than during normal operation For

  see follow the pressure fluctuations which occur, these pressure regulators are provided, as is well known, with a discharge nozzle by means of which

  the air is permanently discharged in the case of a regulation

  Negative use The use of a positive pressure regulator therefore avoids damaging loss of pressurized fluid.

  We obtain a device of a simple construction

  ple when the control piston is arranged coaxially downstream of the shutter element and acts on it by means of a piston rod The piston rod forms the stop serving to limit the opening stroke of

the shutter element.

  * According to another characteristic of the invention

  tion, the retaining device consists of a plate

  that armature fixed to the shutter element and which is as-

  associated with an electromagnet mounted in the housing of the

  pope however it is also possible to use a

  retainer consisting of a mechanical lock

  which acts on the shutter element and can preferably

  It must be pneumatically or electrically operated.

  it is also possible to provide an actuation of the ver-

  rusting by hand while remaining within the framework of the

vention.

  Other features and advantages of the

  vention will be better understood on reading the description

  tion which will follow from an exemplary embodiment and with reference to the accompanying drawings in which, Figure 1 is a diagram of an installation

  compression fitted with the as- adjustment valve

  piration according to the invention, which is shown diagrammatically

  matically by a view in axial central section;

  FIG. 2 represents a variant of the sou-

  suction adjustment valve, also in center section

axial trale.

  In Figure 1, a compressor is shown

  rotary 1 equipped with a drive motor 2, and which

  worse the fluid to be compressed through a relief valve 3

  suction setting From compressor 1, a pressure line 4 leads to a tank 5 which is filled with oil

  in its lower part and the upper part of the

  how much of a pipe 6 leading to the consumer devices

  In addition, there is provided a pipe 7 for injectors

  tion of oil which originates in the lower region

  filled with oil from reservoir 5 and opens into the compressor

  1 The regulation of the compression installation is ensured by means of a proportional regulator 8 which is interposed in a signal line 9, which starts from the

  line 6 leading to consumer devices and

  lead up to the suction adjustment valve 3.

  The suction adjustment valve 3 comprises a valve housing 10 in which is freely mounted in

  translation a shutter element 11 which controls the

  compressor suction line 12 The obturating element

  rator 11 is stressed in the closing direction by

  a non-return valve spring 13 In the central part

  trale of the valve housing 10 is disposed a device

  retaining tif 14 which is constituted in the example of rea-

  reading according to figure 1 by an electromagnet 15 mon-

  tee in the valve housing 10 and an armature plate 16 belonging to this electromagnet and which is fixed

  at the end of the guide rod 17 of the obturating element

  Finally, there is provided a control piston 18 mounted freely in translation in the housing 10 of the valve and which is biased by an adjustment spring 19 The piston rod 20 of the control piston 18 projects towards the armature plate 16 of the obturator element 11 The end of the piston rod 20 forms a stop

  21 which limits the length of the stroke of the obturating element

rector 11.

  The proportional regulator 8 includes a mem-

  brane 22 which is biased on one side by a spring 23 and on the other side by the pressurized fluid supplied via the inlet 24 To the membrane 22 is fixed a valve element 25 which cooperates with a seat of

  valve 26 and controls a channel 28 leading to the outlet 27.

  A discharge nozzle 29 leaves from channel 28 and opens into

  in the open air The preload of spring 23 can be reduced

  glued by means of a screw cap 30.

  In the variant of valve 3 for adjusting the

  the aspiration which is represented on figure 2, the dis-

  positive retaining is constituted by a locking

  canique provided with a pawl 31 mounted oscillating, which is sol-

  licit by a spring 32 and snaps behind the element

  shutter 11 The surfaces of the pawl 31 and the element

  shutter 11 which are pressed against each other are chamfered so that, under the action of the spring 32, the pawl 31 applies the shutter element 11

  on his seat in the closed position For action-

  nement of the pawl 31, a membrane 33 is provided which acts by means of a finger 34 on an extension

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  of the pawl 31 The actuation of the membrane 33 is ensured by a fluid under pneumatic pressure which is introduced via a control line 36 which is provided in a housing cap 38 used to tighten the membrane 33 in a chamber pressure 37 Furthermore, as in the embodiment according to the

  Figure 1, the shutter element 11 is mounted in the box

  tier 10 of the valve by means of a guide rod 17 and it is biased by a non-return valve spring 13 The lifting movements of the shutter element 11 are here also limited by a control piston 18

  which forms a stop 21 by the end of its rod of pis-

  tone 20 The actuation of the ratchet 21 could also be controlled by hand instead of being controlled by the

membrane 33.

  When the compression system represents

  tée in Figure 1 is stopped, the shutter element

  tor 11 closes the suction line 12 under the effect of the action of the non-return valve spring 13 When the compressor I is started, a vacuum is established downstream of the obturator element 11 which tends to immediately open the suction control valve However, the retainer 14 maintains this valve

  setting of the suction 3 closed during the de-

  marrage so that it is possible to start compressor 1 in a decompression state For this purpose,

  in the embodiment according to Figure 1, the electro-

  magnet 15 is excited by means of a power line not shown, so that it attracts the armature plate 16 and thus holds the shutter element Il in

  the closed position As soon as compressor 1 is off

  excited, the excitation of the electromagnet 15 is interrupted and, consequently, the shutter element 11 immediately opens the suction line 12, so that the compressor 1

  starts to pump at full flow When switching on

  shutdown of the compressor, the shutter element 11 behaves, under the action of the non-return valve spring 13, as

  an automatic non-return valve and ensures a closing

  immediate re of the suction line 12 This safely prevents, under the action of the pressure prevailing in the tank 5, the pressurized fluid and the oil

  injected into compressor 1 via the con-

  injection line 7 does not flow back into the suction line

  tion 12 and in a filter which is in any case mounted in

downstream of it.

  The proportional regulator 8 is used to regulate the discharge flow rate of the compressor 1 in

  depending on the pressure in the line 6 me-

  for consumer devices When this pressure prevailing in line 6 has reached a certain value, which can be adjusted by the preload of the spring 23 of the regulator 8, the movable element 25 is lifted from the valve seat 26, following what a regulation signal reaches the valve 3 for adjusting the suction by

  through signal line 9 This signal

  quotes the control piston 18 and displaces the latter

  adjusting the force of the adjusting spring 19 The piston rod

  your 20 then acts in the direction of closure on the element

  shutter 11, which comes to rest on the stop 21 by means of the armature plate 16 The valve

  the suction control then closes with the increase

  ment of the pressure prevailing in the line 6 leading to the consumer appliances, so that the discharge is throttled In this way, an adaptation of the

  delivery rate at the instantaneous value of consumption

  mation by continuous variation When the pressure prevailing in the line 6 leading to the consumer devices has reached a determined maximum value, the suction adjustment valve 3 closes completely The valve, 26 of the proportional regulator 8 then remains open

  so that when the suction control valve 3

  tion is closed, the fluid discharged by the compressor 1

  can still be ejected through the discharge nozzle 29 of the

  proportional regulator 8 As soon as the pressure falls in the

  line 6 leading to consumer devices, the regulation

  proportional valve 8 closes completely or partially and, as a result, the pressure prevailing in the

  signaling 9 is released through the discharge nozzle

  ge 19 At this time, the control piston 18 releases the element

  shutter 11 under the action of the control spring 19 so that the suction control valve 3

  can open again When the valve 25, 26 of the

  proportional regulator 8 is closed, it does not escape

  of pressurized fluid through the outlet nozzle 29

  so there is no loss of pressure La

  discharge nozzle 29 can therefore be produced with a sec-

  relatively large passage without risk of detrimental loss of pressure, so that the

  both clogging and icing of this nozzle.

  The suction control valve according to figure 2 works essentially in the same way as

  the embodiment described with reference to FIG. 1.

  The only difference lies in the retaining device by means of which the shutter element 11 is anchored in the

  closing position to guarantee a start in decom-

  pressure In Figure 2, we can recognize that the

  quet 31 snaps behind the shutter element It under

  the action of spring 22 when this shutter element does not

  from the open position to the closed position.

  The pawl 31 rigidly holds the shutter element 11

  in the closed position until the cham-

  control pressure bre 37 is requested, by the

  through the control line 36, by a pressurized fluid which raises the pawl 31, through the membrane 33 and overcoming the force of the spring 32

  and, in this way, unlocks the shutter element 11.

  This element can then immediately release the suction line.

  piration 12 so that the discharge of the compressor begins The regulation of the discharge rate occurs in the same way as described with reference to FIG. 1, that is to say, under the action of the piston 18

  which acts on the guide rod 17 of the obturating element

  tor 11 via the piston rod 20,

  so that the suction control valve 3 opens

  vre more or less depending on the pressure.

  Using the suction adjustment valve 3 described, it is therefore possible to maintain the line

  compressor 12 closed during start-up

  rage, so we can get a decompression start

  pressure In addition, the discharge flow of the com-

  presser 1 can advantageously be adjusted by variation

  continuous by means of this valve 3 for adjusting the as-

  piration When the compressor is stopped, the suction adjustment valve acts like a non-return valve so that the suction line 12 closes immediately and this is avoided. way with

  certainty the reflux of fluid added with oil.

  Of course, various modifications may be made by those skilled in the art to the device which

  has just been described only by way of non-binding example

  mitative and without departing from the scope of the invention.

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Claims (5)

  1 Suction adjustment valve for   rotary pressers, especially for helical compressors   oil injection, this valve comprising a shutter element which controls the suction line, is elastically biased in the direction of closing and can be moved in the direction of closing by   a control piston guided in a cylinder and stressed   tee by an adjusting spring, characterized in that the shutter element (11) formed separately from the piston   control (18) is biased by a valve spring an-   its own return (13) and is provided with a provision   retaining sive (14), preferably an electrically operated retaining electromagnet (15), by means of which   it can be kept in the closed position.   2 suction control valve according to claim 1, characterized in that the shutter element (11) is associated with a stop (21) which limits the opening stroke of this element and which can be   adjusted by the control piston (18).   3 Suction adjustment valve according to   one of claims 1 and 2, characterized in that   the control piston (18) is biased in the direction of opening of the shutter element (11) by the adjusting spring (19) and in the direction of closing by the control pressure.   4 Suction adjustment valve according to   any one of claims 1, 2 and 3, character-   in that the control piston (18) is arranged axially downstream of the shutter element (11) and acts   thereon by means of a piston rod (20).   Suction adjustment valve according to   any one of claims 1 to 4, characterized   in that the retaining device (14) consists of an armature plate (16) fixed to the obturating element and which is associated with an electromagnet (15) mounted in the valve housing.   6 Suction adjustment valve according to   any one of claims 1 to 4, characterized   in that the retaining device (14) is constituted by a mechanical lock (31) which acts on the shutter element (11) and can preferably be actuated by see pneumatic or electric.