FR2539463A1 - CONTROL DEVICE FOR HELICOIDAL COMPRESSORS - Google Patents

Abstract

THIS CONTROL DEVICE FOR HELICOIDAL COMPRESSORS, ESPECIALLY PROVIDED FOR STARTING AND FOR IDLING REGULATION, IS OF THE TYPE IN WHICH AN ADJUSTING VALVE 4 INTENDED FOR THE REGULATION OF THE FLOW IS INTERCALED IN THE SUCTION DUCT 2 OF THE HELICOID COMPRESSOR 1 THE ADJUSTMENT VALVE IS BYPASSED BY A BYPASS DUCT 12 EQUIPPED WITH A BYPASS VALVE 14 WHOSE PASSAGE SECTION CAN BE ADJUSTED IN AT LEAST TWO STEPS. THE PASSAGE SECTION OF THE BYPASS VALVE 14 CAN BE ADJUSTED BY A CONTROL DEVICE 15 SO AS TO RELEASE A LARGE PASSAGE SECTION FOR STARTING COMPRESSOR 1 AND A SMALLER PASSAGE SECTION FOR IDLE. TO PREVENT THE FLUID FROM BACKFLOWING THROUGH THE BYPASS DUCT 12 IN THE REVERSE DIRECTION OF THE SUCTION, A VALVE 13 IS INSERTED IN THE BYPASS DUCT 12.

Description

The invention relates to a communication device

  for helical compressors, especially for

  start-up and for the regulation of idling,

  which includes a control valve inserted in the suction line of the helical compressor to assist

  regulate the flow and a valve for

  intercalated in a bypass line which

turn the control valve.

  In the regulation of the flow of

  licoids by means of an interposed control valve

  in the suction line, it is necessary to

  keep the control valve closed at the time of installation

  to avoid a sudden overload of the installation

  compression and, in particular, also a sudden overload of the drive motor.

  one must open or keep open a section of pass-

  of a defined area so that it can establish itself

  quickly a pressure that is necessary to ensure cooling by liquid injection and also

  to control the operation of the control valve.

  To keep open the crossing section

  When the control valve is closed, it is known to make the control valve in a non-leakproof construction, for example by providing an adjustable stop screw for the shutter element of the valve.

  adjustment valve, in particular for the adjustment

  ge, or by providing a small opening passage in the adjustment flap itself However, it is not

  It is not possible to adopt these measures in

  compression pressures which are constantly under pressure.

  network and in which, therefore, the

  check valve which prevents backflow of the fluid

  awarded is inserted in the suction line and not

  not in the discharge pipe downstream of the compres-

  because, in these installations, the suction pipe must be sealed when the compressor is stopped. Moreover, a disadvantage

  consists of the passage section of these openings

  passageways can not be adapted to different

  operating conditions of the compressor.

  There are also similar disadvantages in the device also known in which it is provided as bypass valve an electrovalve which

  is open during the start of the compressor

  dal and closed after start-up In addition, in this

  available, it is necessary to provide for

  additional electrical devices for the control of

electro-valve.

  The object of the invention is to improve

  control actuators for helical compressors already known such that, when the compressor is stopped, the suction pipe is reliably closed, and that, on the contrary, at the time of starting and in operation at idle, the bypass valve releases passage sections possessing

different areas.

  According to the invention, this problem is solved by

  the fact that the passage section of the

  It is adjustable in at least two steps and in the bypass line a check valve is interposed which blocks the backflow of the fluid.

  the bypass line, in the opposite direction to the suction

  The use of a bypass valve thus constituted ensures in a simple way that, when the suction pipe is closed tightly by the regulating valve used for the regulation of the flow, it can be released by the intermediate of the bypass line at the start of the compressor a relatively large passage section that will allow a rapid establishment of the pressure and that at the idling speed will be obtained by reducing the passage section an effect of strangulation sufficient to establish

  a depression and thus ensure a reduction in the

  absorbed by the drive motor The flapper

  anti-return interposed in the 7th branch line

  the compressed fluid flows back into the suction line.

  According to another embodiment of the invention,

  The bypass valve can at the same time constitute a non-return valve. Only one valve inserted in the bypass duct is then required.

ensure the desired function.

  In a preferred embodiment of the invention,

  tion, the bypass valve includes an ob-

  turner preferably consisting of a ball that is

  pressed by a return spring on its seat of

  pe in front of which is a race stop that we

  can adjust in the direction of the opening of the

  This is a simple way of constructing a valve, which is composed practically only of

  three turned pieces * and which can

  all the conditions required in the context of the

  The race stop may be composed here of a guided pusher movable in translation in the body of the valve, which can move in

  the direction of the opening of the shutter element under

  of a spring and in antagonism to the

  this of this spring under the action of a fluid under pressure

  which acts via a membrane or a pis-

  ton This also allows to get a simple command

of the bypass valve.

  The device according to the invention can be

  perfected by the fact that the passage section of

  the bypass valve can be controlled by a

  Positive control depending on the network pressure prevailing downstream of the compressor, with the possibility of choosing a large section of passage for the operation

  start-up of the compressor and a passenger section

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  smaller size, preferably adjustable, for the function

  In response to a change in

  state of operation of the compressor, the

  This automatically switches to the passage section required for the current operating status, for example for starting or for idle speed. In addition to this switching, it is possible to

  also provide for the possibility of adjusting the

  passage, for example by screwing one on the other

  two elements of the body of the valve.

  Other features and advantages of the

  will be better understood when reading the description of

  following example of an embodiment and with reference to the accompanying drawings in which, Figure 1 is a diagram of an installation of

  compressor which is equipped with the control device se-

Invention

  Figures 2 and 3 represent a form of

  supply of the bypass valve according to the invention,

  in two different working positions, by one

axial median pe.

  The compression installation shown in FIG. 1 is composed of a helical compressor 1 whose suction pipe is designated by 2 and the

  3-way discharge pipe In the suction pipe

  2 is inserted a control valve 4 which serves to

  flow regulation and is actuated by a

  regulator 5 to which the pressure of a fluid

  as a control variable, via a control line 6 En

  downstream of the compressor, we find first in the con-

  discharge pipe 3 an oil tank 7 from where an oil injection pipe 8 leading to the compressor

  1 In the discharge line 3 is also

  stalled a pressure tank 9, hence driving

leading to user devices.

  The control valve 4 and a check valve 11 also inserted in the suction line 2, are bypassed by a bypass line 12 in which are also interposed a non-return valve 13 and a bypass valve 14 The valve bypassing device 14 can be controlled by means of a

  command 15 which is interposed in a command line

  16 which leads from the pressure tank 9 to the

bypass 14.

  Figures 2 and 3 show an example of

  construction of the bypass valve 14 This valve

  e comprises a valve body composed of two elements 17 and 18 which are screwed into each other by means of a thread 19. In the lower element 18 of the body, there is a valve seat 20 having an air duct.

  passage 21 which is controlled by a ball 22 serving as

  Valve shutter member An outlet duct 23 is provided laterally in the lower member 18 of the body. The ball 22 is loaded by a return spring.

  24 of weak force which applies it to the seat of

  pe 20 The opening stroke of ball 22 is limited

  by a pusher 25 which is g Miidé in the upper element

  17 of the body, with the possibility of moving in translation by overcoming the force of a spring 26, and which is applied to a membrane 28 by its enlarged head 27 By introducing a fluid under pressure by means of

  of a control conduit 29, it is possible to push back the membrane

  do not 28 down to push-button 25 until

  the head 27 abuts against a stop 30 formed in the ele-

  upper body 17, as shown

in Figure 3.

  The operating mode of the device described is as follows: at the time of starting of the helical compressor 1 shown in FIG. 1, the control valve 4 is firstly closed When the compression installation is under zero pressure, for example at the time of the first start or after a prolonged stop, the control valve 4 can not be opened because it is not available in the

  pressure tank 9 of the fluid pressure required

  to operate the control valve 4 through the adjuster 5, however,

  it is necessary to open a passage section sufficient

  large in the suction line so that it can establish a control pressure and also to ensure the lubrication of the compressor 1 from

  of the oil reservoir 7 and through the

  80 oil injection pick It is for this purpose that

  the bypass line 12

  tion 14 interspersed in that conduit is opened in

  permanently, so that we have the section of

  wise needed for start-up.

  As can be seen from Figures 2 and 3, the Courts

  opening of ball 22 of the diverter valve

  14 can be adjusted in two steps. When no pressurized fluid is conveyed through the control conduit 29, the pusher 25 is in its position.

  upper limit, so that the ball 22 of the valve

  pe can describe its complete stroke and that the bypass valve 14 releases a large passage section

  If, on the other hand, a fluid under pressure is

  mined by the control conduit 29, the pusher 25 is pushed downwards, as shown in FIG. 3, so that the stroke of the ball 22 of the valve and, with it, also the section of passage through the

  bypass valve 14 are reduced.

  tif of Figure 1, the modification of the section of

  wise of the bypass valve 14 which has just been de-

  This occurs under the effect of the control device, depending on the pressure in the reservoir

pressure 9.

  When the pressure tank 9 is under

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  pressure or has a relatively low pressure

  ble, the control conduit 29 of the valve

  14 is also under zero pressure so that this valve releases the large passage section The bypass valve 14 takes this position when the compressor 1 is stopped or at the moment when it is due.

  start If the control valve 4 is still closed

  In this case, during the start-up operation, the bypass valve 14 releases a passage section large enough to ensure rapid settlement.

  pressure and sufficient lubrication of the com-

  1 When during the increase of

  pressure in the pressure tank 9, the pressure

  dyes its maximum desired value, the compressor 1 is switched to the idle speed In idle operation, the control valve 4 is closed However, the suction pipe 2 must not be completely closed because otherwise it will not The remaining suction section should however be as small as possible but in any case smaller than the section

  suction released during the start of the installation.

  In order to achieve this result, the

  Bypass gate 14 is switched by the controller 15 to the position shown in Fig. 3, wherein pusher 25 is in its lower limit position and the stroke of ball 22 of the valve is reduced accordingly. exact area of the

  desired section of passage through the diverter valve.

  14 can be precisely adjusted by screwing one of the elements 17 and 18 of the body in the other, to the

means of the thread 19.

  During both start-up and idling, the fluid drawn through

  the bypass valve 14 in the direction of the arrows

  FIGS. 2 and 3 since the ball 22

  the valve is urged towards the seat 20 of the

  poppet by the return spring 24, the diverter valve

  tion 14 plays the role of a check valve

  tower which prevents the fluid from flowing back through the bypass line 12 The bypass valve 14 made

  FIGS. 2 and 3 thus replace the check valve

  ti-return 13 shown in the bypass line

  12 in Figure 1, so that this valve can be sup-

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

  just described as a non-limiting example.

  mitative without departing from the scope of the invention.

R E V E N D I C A T IO N S

  1 Control device for compressor compressors

  unloldals, in particular for starting up and regulating idling; comprising an adjusting valve interposed in the suction line of the helical compressor to provide flow control and a

  bypass valve inserted in a control line

  the riveting which bypasses the regulating valve, this

  characterized in that the passage section of the bypass valve (14) can be adjusted in at least two steps and in that the bypass line (12) is interposed with a non-return valve (13). )

  which prevents the fluid from flowing back through the

  vation (12) in the opposite direction to the suction.

  2 Device according to claim 1, characterized

  in that the bypass valve (14) constitutes

same time a check valve.

  3 Device according to one of claims 1

  and 2, characterized in that the bypass valve

  (14) comprises a shutter member preferably

  by a ball (22) which is pressed by a spring

  return valve (24) on its valve seat (20) opposite the

  which is a travel stop (25) which can be

  in the direction of the opening of the ob-

tor.

  4 Device according to claim 3, characterized

  characterized in that the travel stop is constituted by a pusher (25) guided movably in translation in the body (17, 18) of the valve, which can move in the direction of the opening of the shutter member (22). ) under

  the action of a spring (26), and in antagonism with

  port to the force of this spring under the action of a fluid

  under pressure acting through a membrane

ne (28) or a piston.

  Device according to any one of the r-ven-

2539-46

  1 to 4, characterized in that the section of steps

  of the bypass valve (14) can be

  by a control device (15) as a function of the pressure of the network which runs downstream of the compressor (1), with the possibility of choosing a large section of passage for the operation of starting the compressor (1). )

  and a smaller passage section, preferably

  glable, for idle operation.