EP1072796A2 - Screw-type compressor - Google Patents

Abstract

The cylinder chamber(44) of the compressor has a backflow orifice(58) and at least one intermediate backflow orifice(74,76) establishing a minimum position(Mi) and intermediate position(Z1,Z2) respectively. The control unit(66) in the mode for stepless control of the piston positions in a range between the intermediate position and minimum position activates the backflow orifice, and for stepless control of the piston positions outside the range between the intermediate position and minimum position activates the intermediate backflow orifice. An Independent claim is included for a control unit which activates feed flow in an established cycle.

Description

The invention relates to a screw compressor comprising one housing with one rotor chamber, two in the rotor chamber arranged screw rotor, which in the housing around their respective axes of rotation are rotatably mounted and which with each other are combable drivable to a to be compressed Medium from a suction gas inlet of the housing to a compressed gas outlet to promote the housing and thereby compress it, one movable in the direction of the rotor axes and attached to the Slider chamber adjoining slide for power control over the effective length of the screw rotor, an adjusting device, comprising one pressurized by a medium Cylinder formed by a cylinder chamber and a piston coupled to the slide, and one the Cylinder assigned control device with which in a stepless control mode an inflow and a reflux of the to Actuation of the piston provided medium is controllable.

Screw compressors of this type are from the prior art known. With these is a stepless control mode Control of the actuating device for a supply line the pressure cylinder provided, either through Inflow of the medium actuating the piston or return flow of the the piston actuating medium the piston in all conceivable Positions is movable.

So that the control device of such a screw compressor works reliably, however, it is necessary recognize the position of the piston of the control device can to the screw compressor in the mixed control areas to be able to operate reliably.

For this reason, one of the prior art known screw compressor a position detection for the Piston and / or the slide required, which is expensive. The invention is therefore based on the object To improve screw compressors of the generic type in such a way that the structurally as simple as possible Control device works reliably.

This task is the beginning of a screw compressor described type according to the invention solved in that the Cylinder chamber a return opening defining a minimum position when the piston is activated any position between the maximum position and the minimum position is retractable to the minimum position that the Cylinder chamber defining at least one intermediate position Has intermediate reflux opening when they are activated the piston can be moved up to this intermediate position is that the control device in the control mode for stepless Control of the piston position in a partial control range between the intermediate position and the minimum position Return opening activated and that the control device for stepless control of piston positions outside the Sub-tax area between the intermediate position and the Minimum position the corresponding intermediate reflux opening activated.

The advantage of the solution according to the invention is thus too see that the possibility exists by setting the reflux of the medium actuating the piston via the Intermediate return opening the piston only in one to operate the desired sub-tax area and thus also for the control device provides reliable information in this regard to make available that undesired partial control areas, for example the sub-tax area between the Intermediate position and the minimum position, for the stepless Control of the piston can be excluded.

So there is the possibility that position monitoring the piston and / or the slide, can be omitted and still the control device with the required reliability controls, the control states either directly the type of control or by detecting the type of Control are recognizable.

In principle, the solution according to the invention is with a single intermediate reflux port fully functional.

However, it is particularly favorable if the cylinder chamber several defining other sub-tax areas Intermediate reflux openings are assigned, and if the Control device the minimum permissible position of the piston in the respective sub-tax area by the activated activated intermediate reflux opening.

This means that with this solution there is the possibility several sub-tax areas, each with a minimum permissible Position of the piston by activating different ones To define intermediate reflux openings.

A particularly advantageous control mode provides that the Control device the piston only in outside of the partial tax area between the intermediate position and operates the minimum tax areas, that the control device only the corresponding intermediate reflux opening and not additionally the reflux opening for Control activated, so that the design There is a possibility of the undesirable partial tax area, for example between the intermediate position and the Minimum position of the partial tax area to be excluded.

To be able to carry out an exact stepless control, is it is necessary for the control device to change the position of the Recognizes Kolbens. For this reason, it is preferably provided that the control device the position of the piston starting from the activated intermediate reflux opening corresponding intermediate position as a reference position determined and is therefore able to proceed from this Reference position, for example by integrating the Flow times and return times, the position of the piston to be determined at least approximately, with an exact new entry the position of the piston is always possible when this moves back to the respective intermediate position is to which then the outgoing again Position of the piston can be determined.

Around the reflux port and the intermediate reflux ports to be able to be activated by the control device, for example complex valves conceivable. An easy way provides that each of the reflux ports and intermediate reflux ports a controllable by the control device Valve is assigned.

The valves could, for example, be designed such that quantity control is also possible with these. To the However, the control device is particularly simple can, it is preferably provided that each valve is only one between a flow position and a blocking position is switchable valve and thus has only two switching states.

With regard to the constructive training of the actuating device, in particular to achieve the minimum division the most different variants possible. For example, it would be conceivable, the piston double-sided with a medium to act upon, the one medium being the force to move of the piston from the minimum position to the maximum position generated and the other medium the restoring force to move back of the piston in the direction of the minimum position Activation of the reflux openings or intermediate reflux openings generated.

In terms of design, however, it is particularly simple if the piston towards its minimum position by an elastic Energy storage, for example a spring is acted upon, which always ensures that the piston when activated at least one reflux opening or intermediate reflux opening moves in the direction of the minimum position, if this Backflow opening or intermediate reflux opening still in the Cylinder volume enclosed between the piston and the cylinder chamber flows.

Regarding the coupling between the piston and the For example, a slide would still be conceivable mechanical translation or flexible coupling to provide. However, it is particularly easy if the Slider connected to the piston via an actuation control is.

Preferably, the slide is rigid with the piston connected.

However, the solution according to the invention does not only concern one Operation of the screw compressor according to the invention in one stepless control mode.

Alternatively or additionally, the solution to this is task of a screw compressor according to the invention comprising a housing and a rotor chamber, two in the Rotor chamber arranged screw rotor, which in the Housing are rotatably mounted about their respective axes of rotation and which are intermeshable drivable to one compressing medium from a suction gas inlet of the housing to promote and compress a compressed gas inlet of the housing, a movable in the direction of the rotor axis and on the rotor chamber adjoining slide for power control over the effective length of the screw rotor, an adjusting device, comprising one pressurized by a medium Cylinder formed by a cylinder chamber and a piston coupled to the slide, and one the Cylinder assigned control device with which in a stepless control mode an inflow and a reflux of the to Actuation of the piston provided medium is controllable, solved according to the invention in that the cylinder chamber has a minimum position defining reflux opening, when the piston is activated in the minimum position is movable that the cylinder chamber at least one Has intermediate reflux opening defining intermediate position, when the pistons are activated up to this Intermediate position is movable and that the control device in the stepped control mode at averaged over time constant inflow only the reflux opening or one of the Intermediate reflux openings activated.

The advantage of this solution is the fact that it is due to the same constructive basis without conversion measures there is the possibility of the screw compressor according to the invention to operate in step control mode.

According to the invention, this is by activating the reflux opening or the intermediate reflux port possible reflux of the medium acting on the piston is always larger than that Inflow through which the piston moves towards the minimum position is movable.

It is particularly favorable if the control device in the stepped control mode activated the inflow clocked because thereby particularly advantageous the return of the piston is initiated because there are times when there is no inflow of the medium acting on the piston and thus the return flow and the return movement of the piston in Use the direction of the minimum position in an advantageous manner can. Thus, the response behavior of the power control improved.

It is particularly advantageous if the control device activated the inflow in a definable cycle.

It is also advantageous if the control device Inflow in the fixed cycle for a fixed period of time activated, the definable clock and the definable Period not over the entire operating hours of the Screw compressor must be set to the same values must, but according to changing circumstances, for example changing operating temperature, reset can be, for example, for oil as a medium Acting on the piston adapts to the viscosity to make the same.

Preferably also takes place in the stepless control mode Clocking the inflow and in particular also clocking the Reflux.

Other features and advantages are the subject of the following Description and the graphic representation of an embodiment.

Fig. 1 shows a schematic representation of a Screw compressor according to the invention with a schematic longitudinal section through a housing of the same.

An embodiment of a screw compressor according to the invention, shown in Fig. 1 includes one as a whole 10 designated housing, which forms a rotor chamber 12, in which two are aligned parallel to each other and with each other intermeshing screw rotors 14 about their respective axes of rotation 16 are rotatably mounted, the bearing of the screw rotor 14 preferably arranged on both sides of the same Stub shaft 18 and 20 in bearings provided in the housing 10 22 or 24 takes place.

In the housing 10 there is also a screw rotor on the suction side 14 arranged suction gas inlet 26 arranged and a the pressure side of the same lying gas outlet 28, the Screw rotor 14 a medium to be compressed from the suction inlet Promote 26 to the compressed gas outlet 28 and compress it.

A slide 30 is used to adjust the compressor output provided which in the housing 10 in a direction 32nd parallel to the axis of rotation 16 of the screw rotor 14 is stored and starting from the compressed gas inlet 28 in Extends direction of the suction gas inlet 26, with it Slider top 34 adjacent to the screw rotor 14 and with a front slide edge 36 defines the location which a compression of the medium to be compressed by the two intermeshing screw rotor 14 takes place.

The slide 30 is fixedly connected to an actuating rod 38, with which one is labeled 40 as a whole Adjustment device of the slide 30 adjustable in the direction 32 is.

The actuating device 40 comprises a cylinder housing 42, which encloses a cylinder chamber 44 in which a piston 46 is movable, which is fixedly connected to the actuating rod 38 is, the actuating rod 38 is preferably a Piston rod of the piston 46 forms.

The piston 46 is also parallel to the direction 32 in the cylinder chamber 44 can be moved from a minimum position Mi, for example, a service of the order of magnitude corresponds to 25% of the maximum output of the compressor, up to a maximum position Ma, which is the Maximum performance of the compressor corresponds, and intermediate positions Z1 and Z2, which will be described in more detail below are explained.

The minimum position Mi of the piston corresponds to one minimal enclosed between cylinder chamber 44 and piston 46 Maximum cylinder volume and the Ma position enclosed between the piston 46 and the cylinder chamber 44 Cylinder volume while the intermediate positions Z1 and Z2 correspond to cylinder volumes between the minimum cylinder volume and the maximum cylinder volume lie.

The adjusting device 40 is used to adjust the piston 46 pressurized oil, for example by an oil pressure pump 50 or one with the final pressure of the compressing medium acted on a reservoir for the pressure on the piston is maintained becomes. The oil flows through an oil pressure pump 50 Supply line 52 formed via a throttle 54, for example as a capillary, to a supply line 56, which with a supply opening 58 in the cylinder chamber 44 flows. The supply line 56 is also with a Return line 60 connected to the suction gas inlet 26 of the Housing 10 leads.

To control individual positions of the piston 46 in the Cylinder chamber 44 is an inlet valve in the inlet line 52 62 provided and a return valve in the return line 60 64, both of which are preferably electromagnetic via a control device designated as a whole by 66 are controllable.

To move the piston 46 from the minimum position Mi in another position between the minimum position Mi and the Maximum position Ma is the inlet valve 62 through the Control 66 opened, the oil pressure pump 50 oil via the Supply line 52, the supply line 56 and the supply opening 58 pumps into the cylinder chamber 44 and thus acts on the piston 46 while increasing the cylinder volume, until the desired position of the piston 46 is reached. Then the inlet valve 62 is closed. The slide 30 can thus preferably be in one position move in which the compressor output between the minimum value and the maximum value, with the minimum position Mi of the piston 46 preferably the position is minimal Power of the slide 30 is assigned and the maximum position Ma of the piston 46 the position of maximum power the slider 30.

To move the piston 46 from a position between the minimum position Mi and the maximum position Ma in the direction the minimum position Mi, the return valve 64 from the Controller 66 opened so that oil from the from the cylinder chamber 44 and the piston 46 enclosed cylinder volume can flow out via the return line 60, and preferably in the process flows to the suction gas inlet 26 so that the piston 46 moves in the direction of the minimum position as long as long the return valve 60 is opened by the control device 66 is held.

After the return valve 64 closes, the piston 46 remains in the position reached.

It is preferable to move all positions between the minimum position Wed and set the maximum position Ma can, the supply opening 58 facing a piston crown 68 in a cylinder housing bottom 70 of the cylinder housing 42 arranged.

There are also 72 intermediate return openings in a cylinder housing jacket 74 and 76 at different distances from the Minimum position Mi of the piston 46 arranged with Intermediate return lines 78 and 80 are connected, which in turn into the return line 60 between the return valve 64 and the suction gas inlet 26 open. Each of the intermediate return lines 78 and 80 is with an intermediate return valve 82 or 84 provided with which the respective Intermediate return line 78 and 80 can be closed.

Due to the position of the intermediate return openings 74 and 76 in Distance from the minimum position Mi of the piston 46 is Position of these assigned intermediate positions Z1 or Z2 of the piston 46 set, with a stepless Control mode, the intermediate positions Z1 and Z2 are such that the piston 46 standing in this in front of the intermediate return openings 74 or 76 stands.

By controlling the intermediate return valves 82 and 84 by means of the control device 66 there is now the possibility Oil through the intermediate return ports 74 or 76 Allow cylinder chamber 44 to flow, if that respective cylinder volume up to the intermediate return openings 74 or 76 or extends beyond these.

The intermediate positions Z1 and Z2 are preferably such that the intermediate position Z1 corresponds to a position of the slide 30, where the screw compressor in one medium power range, i.e. in the Order of 50% works. Furthermore, the intermediate position For example, Z2 is defined to be one Position of the slide 30 corresponds in which this Screw compressors with a performance of the order of magnitude works from 70% to 80%.

But there are also other definitions in the manner according to the invention the intermediate positions Z1 and Z2 possible. Further is it is also possible according to the invention to have more than two intermediate positions Z1 and Z2 to be provided.

In addition, piston 46 or slider 30 is preferred still with an elastic energy accumulator, that is, for example a spring 90 so acted that both the piston 46 and the slide 30 have the tendency to To reduce the cylinder volume, i.e. without applying oil pressure of the cylinder volume between pistons 46 and Cylinder chamber 44 in the minimum position Mi of the piston 46 and thus the position of minimum output of the screw compressor to pass over.

The screw compressor according to the invention can now be like operate in stepless control mode:

When starting the screw compressor, due to the elastic energy storage 90 of the pistons 46 and one if necessary, previous opening of the return valve 64 and thus also the slide 30 in the minimum position, the is the name of the screw compressor drives with minimal performance on. If the screw compressor should now have a higher one Power operated, the inlet valve 62 in the Inlet line 52 opened and consequently the oil pump 50 delivers Oil via the supply line 52 into the supply line 56 and thus via the supply opening 58 into the piston 46 and the cylinder chamber 44 have limited cylinder volumes, whereby this is increased and the piston 46 moves from the minimum position Wed moved towards the maximum position.

This can increase the performance of the screw compressor to any possible position of the piston 46 respectively.

If a position of the piston 46 between the minimum position Wed and the intermediate position Z1 reached, so can by blocking the inlet valve 62 upright this position obtained or by opening the return valve 64 this Position changed again in the direction of the minimum position Mi. be, the minimum position Mi when closed Inlet valve 62 can be started quickly and at open inlet valve 62 can be started slowly, if more oil flows out through the return valve 64 than through the inlet valve 62 flows in.

Usually, however, there is a desire to use screw compressors in an upper performance range, that is in one Power range above a minimum value in the order of magnitude to operate by 50%.

For this reason, usually by opening the inlet valve 62 in the inlet line 52 of the piston 46 so far moves that he reaches the intermediate position Z1 or himself moved beyond this in the direction of the maximum position Ma.

To the screw compressor according to the invention in the to operate in the upper performance range and be sure to can that without monitoring the position of the piston 46th and / or the slider 30 can be prevented be driven back so far that they are the lower one again Performance range between the intermediate position Z1 and When the minimum position is reached, the control device 66 operates in the upper performance range in such a way that they are used for the procedure of the piston 46 in the direction of the maximum position Ma the inlet valve 62 opens and thus via the inlet line 52 and the Supply line 54 oil in the piston 46 and the Enter cylinder chamber 44 enclosed cylinder volume to let.

However, to retract the piston 46 in the direction the return valve 64 is not opened in the minimum position, but the intermediate return valve 82 in the intermediate return line 78. This has the consequence that the piston 46th can only move as far in the direction of the minimum position, until it reaches the intermediate position Z1, in which the Piston 46 is in front of the intermediate return opening 74 and thus when moving further in the direction of the minimum position Intermediate return opening 74 automatically blocked and thus also the return of oil from the cylinder volume into the Intermediate return line 78 prevented.

The movement of the piston 46 to the intermediate position Z1 can only opening the intermediate return valve 82 quickly and with additional opening of the inlet valve 62 slowly if provided by the intermediate return valve 82 more oil flows out than flows through the inlet valve 62.

This inevitably ensures that the piston 46 in Direction of the minimum position not over the intermediate position Z1 is moved out. This is also 66 for the controller without monitoring the position of the piston 46 and / or the Slider 30 recognizable that the piston 46 in one position which has at least one capacity of the compressor in corresponds to the order of 50%, but in no way is below this value. Thus, it is only because the Control device 66 only the inlet valve 62 and that Intermediate return valve 82 actuated, a control or regulation area given for the piston, the desired value of not less than 50%, but between the intermediate position Z1 and the maximum position Ma lies.

If the control range for the piston 46 is still on higher values are limited, this is done after adjustment of the piston 46 to at least the intermediate position Z2 the control device 66 merely actuates the Inlet valve 62 and that of the intermediate return line 80 Intermediate return valve 84 so that the piston 46 at its movement in the direction of the minimum position only the Can reach intermediate position Z2, for example in the The order of magnitude between 70% and 80% of the performance of the compressor lies, and this intermediate position Z2 - in same way as in connection with the intermediate position Z1 described - with such actuation of the Intermediate return valve 84 and holding the return valve 64 and the intermediate return valve 82 in the closed Position due to the structural arrangement of the intermediate return opening 76 not fallen below without one Monitoring the position of the piston 46 is required.

The control device 66 can in the inventive Screw compressors, however, are not only described stepless control mode work, in which ultimately one stepless positioning of the piston between the minimum position Wed and the maximum position Ma is possible.

Alternatively, the control device according to the invention also work in a stepped control mode, in which only the intermediate position Z1, the intermediate position Z2 and the maximum position Ma next to the minimum position Mi are approachable.

For this purpose, the inlet valve 62 is, according to the invention, in one fixed clock for a fixed time interval opened so that the pressurized oil in the through the Piston 46 and the cylinder chamber 44 enclosed cylinder volume entry. Are both the return valve 64 and the intermediate return valves 82 and 84 are closed, so thereby the piston 46 each time the pressurized is supplied standing oil in the direction of the maximum position Ma, see above that after one by the time intervals for feeding the Oil set total interval the maximum position Ma is achieved.

However, if only the intermediate position Z1 is to be reached, then the intermediate return valve 82 is opened, resulting in that when the piston is in the intermediate position Z1, a slight movement of the piston 46 over the Intermediate position Z1 also causes the piston Z1 to Intermediate return opening 74 releases and thus that over the Supply opening 48 oil supplied to the cylinder volume again via the intermediate return opening 74 and the Intermediate line 78 flows out, so that the piston 46 always slightly moved around the intermediate position Z1 and thus can be defined in this.

In the same way, there is also the possibility of the piston 46 in the intermediate position Z2 by opening the intermediate return valve 84 and keeping the return valve 64 and to hold the intermediate return valve 82.

Finally, there is also the option of the minimum position Mi to achieve that the return valve 64th is opened and thus more oil from the cylinder volume can flow out than via the inlet valve 62 and the throttle 54 flows.

It is also preferred when switching off and before switching on the return valve 64 opened.

The functioning of the screw compressor according to the invention in the staged or stepped control mode assumes that always at least as much oil through the respective return valves 64, 82 and 84 can drain than through the inlet valve 62 can flow. Preferably the inflowing Oil quantity should be set so that it is always less than via the return valves 64, 82 and 84 when activated same returning amount of oil.

The clocked operation of the inlet valve 62 also creates still the possibility by changing the clock frequency or the respectively open period of the inlet valve 62 die to vary the amount of oil supplied, for example with yourself changing oil temperature or changing other Conditions that affect the flow behavior of the oil, in particular when flowing through the throttle 54.

Claims (12)

Screw compressor comprising a housing with a rotor chamber, two screw rotors arranged in the rotor chamber, which are mounted in the housing about their respective axes of rotation and which can be driven to mesh with one another in order to convey a medium to be compressed from a suction gas inlet of the housing to a compressed gas outlet of the housing and to compress, a slide movable in the direction of the rotor axes and adjacent to the rotor chamber for power control over the effective length of the screw rotor, an actuating device comprising a cylinder pressurized by a medium, formed by a cylinder chamber and a piston coupled to the slide, and control device assigned to the cylinder, with which in an infinitely variable control mode an inflow and a backflow of the medium provided for actuating the piston can be controlled,
characterized in that the cylinder chamber (44) has a reflux opening (58) defining a minimum position (Mi), upon activation of which the piston (46) moves from any position between the maximum position (Ma) and the minimum position (Mi) to the minimum position (Mi) It is retractable that the cylinder chamber (44) has an intermediate reflux opening (74, 76) defining at least one intermediate position (Z1, Z2), upon activation of which the piston (46) can be moved up to this intermediate position (Z1, Z2) and that the control device (66) in the control mode for stepless control of the piston positions in a partial control range between the intermediate position (Z1, Z2) and the minimum position (Mi) activates the backflow opening (58) and for the stepless control of piston positions outside the partial control range between the intermediate position (Z1, Z2 ) and the minimum position (Mi) the corresponding intermediate reflux opening (74, 76) activated. Screw compressor according to claim 1, characterized in that the cylinder chamber (44) has several intermediate reflux openings (Z1, Z2) and that the control device (66) the minimum permissible position of the Piston (46) in the respective partial control range the activated intermediate reflux opening (74, 76) specifies. Screw compressor according to claim 1 or 2, characterized characterized in that the control device (66) the Piston (46) thereby only in outside of Sub-tax area between the intermediate position (Z1, Z2) and the minimum position (Mi) partial tax areas operates that it only the appropriate Intermediate reflux opening (74, 76) for control activated. Screw compressor according to one of the preceding Claims, characterized in that the control device (66) starting from the position of the piston (46) from the activated intermediate reflux opening (74, 76) corresponding intermediate position as a reference position determine. Screw compressor according to one of the preceding Claims, characterized in that each of the reflux openings and intermediate reflux ports (58, 74, 76) a valve controllable by the control device (66) (64, 82, 84) is assigned. Screw compressor according to claim 5, characterized in that valve (64, 82, 84) is only between one Flow position and a blocking position switchable Valve is. Screw compressor according to one of the preceding Claims, characterized in that the piston (46) towards its minimum position (Wed) by one elastic force accumulator (90) is applied. Screw compressor according to one of the preceding Claims, characterized in that the slide (30) via an actuating rod (38) with the piston (46) connected is. Screw compressor according to the preamble of claim 1 and / or according to one of the preceding claims, characterized in that the cylinder chamber (44) a a reflux opening defining a minimum position (Mi) (58), when activated, the piston (46) any position between the maximum position (Ma) and the Minimum position (Mi) retractable to minimum position (Mi) is that the cylinder chamber is at least one one Intermediate position (Z1, Z2) of the piston (46) defining Intermediate reflux opening (74, 76), at the Activate the pistons up to this intermediate position is movable and that the control device (66) in a stepped control mode at averaged over time constant inflow only the reflux opening (58) or one of the intermediate reflux openings (74, 76) activated. Screw compressor according to claim 9, characterized in that the control device (66) in the staged Control mode activated the inflow clocked. Control device according to claim 10, characterized in that the control device (66) the inflow in activated a definable clock. Control device according to claim 10 or 11, characterized characterized in that the control device (66) the Inflow in the definable cycle for a definable Duration activated.

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