DE102005016433A1 - Refrigerant compressor - Google Patents

Abstract

To a refrigerant compressor for refrigeration systems, comprising at least one cylinder unit having a cylinder housing and a piston oscillatingly movable in the cylinder housing, a cylinder head, with an inlet flowed through by an inlet flow of the at least one cylinder unit inlet chamber and with an outlet of the at least one cylinder unit interspersed outlet chamber and a switching valve for interrupting the intake flow to be improved so as to be operable in any partial load ranges, it is proposed that a control is provided for driving the shift valve, which for operating the refrigerant compressor in a lower part load range, the switching valve in successive, one opening interval and a closing interval of the switching valve operates at comprehensive switching intervals that are shorter than a shortest period of time, after which a temperature of an evaporator in the operating refrigeration plant ge has increased by interruption of the inlet flow by about 10%.

Description

The The invention relates to a refrigerant compressor for refrigeration systems comprising at least one cylinder unit comprising a cylinder housing and one in the cylinder housing having oscillating movable piston, a cylinder head, with one of an inlet stream the flowed through at least one cylinder unit inlet chamber and with one of a outlet stream the at least one cylinder unit interspersed outlet chamber, and a switching valve for interrupting the intake flow.

such Refrigerant compressor are known from the prior art, in these consists with the Switching valve the possibility permanently switch off one or more cylinder units or permanently switch on.

With this solution is a control of the mass flow rate only according the relationship the stroke volume of the deactivated cylinder units and the stroke volume the working cylinder units possible.

Of the The invention is therefore based on the object, a refrigerant compressor of the generic type to improve so that this is operable in any part load ranges.

These Task becomes with a refrigerant compressor The type described above according to the invention achieved in that a controller is provided for driving the switching valve, which for operation of the refrigerant compressor in a lower part load range, the switching valve in successive, one opening interval each and a closing interval the switching valve comprehensive switching intervals operates, which are shorter as a shortest Period of time after which a temperature of an evaporator in the working refrigeration system at an interruption of the inlet flow increased by about 10% is.

Of the Advantage of the invention is solution to see that this the possibility opened, one Refrigerant compressor, in particular a reciprocating compressor in a lower part load range operate at any part load, as by the ratio of the opening intervals and the closing intervals within each switching interval of the mass flow to be compressed steplessly and is freely adjustable.

there be for the switching intervals have chosen durations that are sufficiently short so that due of inertia the reaction of the refrigeration system according to the invention on the switching intervals only insignificant temperature fluctuations in the evaporator of the refrigeration systems arise, which is a precise Control of the temperature does not affect.

alternative to the solution described above is in a further embodiment a refrigerant the type described above, a controller for driving the Switching valve provided, which for the operation of the refrigerant compressor in a lower part load range, the switching valve in successive, one opening interval each and a closing interval the switching valve comprehensive switching intervals operates, which are shorter as about 10 seconds.

By such a limitation of the duration of the switching intervals is also in accordance with the invention the possibility created, the refrigerant compressor in the lower part load range with arbitrarily adjustable part load to operate without the pressure fluctuations in the refrigeration system occur, which is the quality the regulation of the same.

Yet it is more advantageous if the switching intervals shorter than approximately 2 seconds are.

Around to operate the switching valves effectively is preferably provided that the switching intervals longer as about 0.02 seconds are.

Yet it is more advantageous if the switching intervals longer than 0.5 seconds and it is particularly favorable if the switching intervals longer than 0.1 seconds.

Especially it is advantageous for a switching of the switching valve when the switching intervals of a switching frequency which are smaller than a natural frequency of the switching valve is.

Yet it is better if the switching intervals correspond to a switching frequency, by more than a factor of 5 smaller than a natural frequency of the switching valve is.

In principle, it would be conceivable with the control according to the invention in the lower part load range, for example, a part of the cylinder units turn off and only a part of the cylinder units in the switching intervals to operate.

A especially appropriate solution, however, looks before that the Control in the lower part load range all cylinder units of the refrigerant compressor operates in the switching intervals.

Furthermore, it is conceivable, even in the upper Part load range only a part of the cylinder units off and operate another part of cylinder units in the switching intervals.

Especially Cheap it is however, if the control in the entire partial load range all Cylinder units operates in the switching intervals.

Regarding The duration of the switching intervals are the most varied Possible solutions conceivable. This is one of the reasons the simplicity particularly favorable Variant ago, that the Control operates with time-constant switching intervals.

A another advantageous solution provides that the Control the switching intervals according to a drive speed of the refrigerant compressor varied.

Regarding the formation of the switching valve have been no further details made.

So would it be conceivable, the switching valve in such a way that this directly, for example magnetically controlled, to the inlet stream acts.

Out establish However, the required high valve forces, it has as proven advantageous when the switching valve is a servo valve.

Especially is it cheap, when the servo valve one by one with the pressure in the outlet chamber related Pressure actuated valve body includes.

Around to make sure that valve body the not brought about by the pressure in the outlet chamber end position automatic assumes, it is preferably provided that the valve body by a opposite to the action of the pressure acting on the valve body elastic force storage is applied.

Regarding the operation of the valve body the pressure in the outlet chamber are the most diverse constructive solutions conceivable. For example would be solutions with by the pressure in the outlet chamber acted upon membranes or the like conceivable.

A particularly expedient solution provides that the valve body with one related to the pressure in the outlet chamber Pressure applied and guided in a switching cylinder housing switching piston is coupled, which then actuates the valve body.

Regarding the application of the switching piston, it has to be advantageous proven when the switching piston and the shift cylinder housing a switching cylinder chamber enclose and when the pressure in the switching cylinder chamber is controllable.

Further it is favorable for constructive reasons, if the valve body and the switching piston form a unit which is guided in the switching cylinder housing.

Of Further, it is favorable in such a servo valve, if this comprises a controllable by the controller control valve.

One Such control valve is for example as fast-reacting, electrically actuated solenoid valve or similarly constructed valve formed.

To the Operating the servo valve is in an advantageous embodiment provided that the Control valve a connection channel between the control cylinder chamber and the outlet chamber opens or closes so that in easy way the way consists, the switching piston with under pressure in the outlet chamber pressurize standing medium.

Around in such a servo valve the highest possible natural frequency and thus to achieve short switching time is preferably provided that the Natural frequency of the unit consisting of switching piston, valve body and elastic force storage at least the natural frequency of the switching valve equivalent.

A Such high natural frequency of the switching valve can be achieved in particular if the control piston is made of a lightweight material.

One Such lightweight construction material may for example be a light metal or a plastic, for example, a fiber-reinforced plastic, be.

A further advantageous embodiment of the control piston provides that this designed as a hollow body is, so too thereby a high natural frequency of the unit of control piston, valve body and elastic energy storage is accessible.

Further Features and advantages of the invention are the subject of the following Description and the drawings of some embodiments.

In show the drawing:

1 a schematic representation of a cooling system according to the invention;

2 a cross section along line 2-2 through a refrigerant compressor of the refrigeration system according to the invention;

3 a section through a switching valve integrated in a cylinder head in the open position of a valve body of the switching valve;

4 similar to a cut 3 in a closed position of the valve body of the switching valve;

5 a schematic representation of a switching interval comprising an opening interval and a closing interval;

6 a schematic representation of a behavior of the temperature of the evaporator in the refrigeration system in the interruption of the compression of refrigerant;

7 similar to a cut 3 by a second embodiment of a refrigerant compressor according to the invention and

8th similar to a cut 4 by the second embodiment of a refrigerant compressor according to the invention.

An embodiment of a whole as 10 designated refrigeration system according to the invention comprises a refrigerant compressor 12 , from its high-pressure connection 14 a line 16 to one as a whole with 18 designated condenser leads, in which the compressed refrigerant condenses by heat removal.

From the condenser 18 flows liquid refrigerant in a pipe 20 to a collector 22 , in which the liquid refrigerant collects and from which this then via a line 28 to an expansion valve 30 for an evaporator 32 flows.

After flowing through the evaporator 32 the vaporized refrigerant flows through a pipe 34 to a low pressure connection 36 of the refrigerant compressor 12 ,

As in 2 shown, is the refrigerant compressor according to the invention 12 designed as a reciprocating compressor and includes a compressor housing 40 , in which two V-shaped cylinder banks are arranged 42a and 42b are provided, each of which at least one, in particular two or more cylinder units 44 includes.

Each of these cylinder units 44 is formed of a cylinder housing 46 in which a piston 48 characterized oscillating is that the piston 48 through a connecting rod 50 drivable, which in turn on an eccentric 52 an eccentric shaft 54 sitting, for example, by an electric motor 55 is driven.

The cylinder housing 46 each of the cylinder units 44 is through a valve plate 56 completed, on which a cylinder head 58 is arranged.

Preferably covers the valve plate 56 not just a cylinder housing 46 a cylinder bank 42 , but all cylinder housing 46 the respective cylinder bank 42 and in the same way engages over the cylinder head 58 also all cylinder housings 46 the respective cylinder bank 42 ,

The compressor housing 40 further includes one with the low pressure port 36 communicating inlet channel 60 , which for example in the compressor housing 40 is integrated.

As in 3 shown enlarged, is each cylinder bank 42 as a whole with 70 assigned switching valve, which serves to one of the inlet channel 60 in the respective cylinder head 58 , in an inlet chamber 72 the same through the valve plate 56 passing inlet stream 74 of refrigerant to break.

Is the switching valve 70 opened, so has the inlet stream 74 the possibility of having one in the valve plate 56 provided inlet opening 76 and one on the valve plate 56 provided inlet valve 78 in one of the respective piston 48 and the respective cylinder housing 46 and the valve plate 56 limited cylinder chamber 80 to enter in this by the oscillating movement of the piston 48 to be compressed so that an outlet opening 82 and an exhaust valve 84 an outlet stream 86 from the cylinder chamber 80 exit and into an outlet chamber 88 of the cylinder head 58 entry.

The switching valve 70 is designed as a servo valve, which in the cylinder head 58 is integrated and a valve body 90 having one in the valve plate 56 provided inflow opening 92 the inlet chamber 72 is closable.

The valve body 90 is also on a control piston 94 arranged, which in a switching cylinder housing 96 is guided, so that the switching piston 94 through in a switching cylinder chamber 98 present pressure in the direction of the valve plate 56 is movable to the inlet opening 92 to close in the same.

One from the switch cylinder housing 96 , the control piston 94 and the shift cylinder chamber 98 formed switching cylinder unit 100 in the cylinder head 58 is integrated, is via a control valve 110 controllable, which has an electromagnetically movable control piston 112 includes, with which a control valve seat 114 is closable, wherein the control piston 112 and the control valve seat 114 intended to provide a connection between one to the outlet chamber 88 leading pressure channel 116 and one to the shift cylinder chamber 98 leading pressure feed channel 118 for the shift cylinder 100 to interrupt or release.

Is the connection between the high pressure channel 116 and the pressure supply channel 118 released, so is the switching cylinder chamber 98 below that in the outlet chamber 88 prevailing high pressure and consequently moves the control piston 98 in the direction of the valve plate 56 and presses the valve body 98 against this, around the inlet 92 in the valve plate 56 to close.

It acts on the control piston 94 by the high pressure in the switching cylinder chamber 98 acting force the power of an elastic force accumulator 120 opposite, which on the switching cylinder housing 96 supported on the one hand and on the other hand on the scarf piston 98 acts so that this is from the valve plate 56 moved away and thus the valve body 90 in a the inflow opening 92 moving position.

In particular, the switching piston 94 with a pressure relief channel 122 provided, which of one of the switching cylinder chamber 98 facing opening to one, in 4 illustrated outlet opening 124 which leads into the the inflow opening 92 closing position of the valve body 90 and the control piston 94 in the inlet chamber 72 empties. The pressure relief channel 124 causes it in case of an interruption of the connection between the high-pressure channel 116 and the pressure supply channel 118 the pressure in the switching cylinder chamber 94 quickly collapses and thus under the effect of elastic energy storage 120 the control piston 94 together with the valve body 90 in a the inflow opening 92 releasing, in 3 move shown position.

The switching valve 70 is through an in 1 shown control 130 be controlled such that this in continuously successive switching intervals SI, the switching valve 70 closes and opens, wherein each of the switching intervals SI has an opening interval O, in which the valve body 90 in its releasing position, a passage of the inlet stream 74 through the inlet opening 92 allows, as well as a closing interval S, in which the valve body 90 , as in 4 shown, in its closing position, the passage of the inlet stream 74 through the inlet opening 92 blocked.

Within the duration of the respective switching interval SI can now in all partial load ranges the duration of the opening interval O and the closing interval S be set variably relative to each other, so that either the opening interval O is larger as the closing interval or the other way around.

in the Extreme case may be the opening interval O essentially over the entire duration of the switching interval S extend during the closing interval S becomes arbitrarily small, or vice versa, the closing interval S essentially over extend the entire duration of the switching interval SI, so that the opening interval O becomes arbitrarily small.

As in the refrigeration system according to the invention 10 via the expansion valve 174 In general, an evaporation of liquid refrigerant is always performed, leads to an interruption of the compression of refrigerant through the refrigerant compressor 12 to a rise in temperature T in the evaporator 32 ,

However, the system is provided with a reaction inertia, so that in an interruption of the extraction of refrigerant from the evaporator 32 the temperature T of the evaporator 32 does not rise immediately, but, as in 6 shown, a period of time Z is required to increase by a value D.

As long as the value D is less than 10% of an outlet temperature T _{A of} the evaporator, these fluctuations are irrelevant to the function of the refrigeration system according to the invention.

For this reason, the switching interval SI is set to be shorter than the time Z that elapses until the temperature T of the evaporator 32 starting from a temperature T _A , the evaporator 32 by a value D of about 10%, more preferably about 5%, has risen when a sudden interruption of the extraction of refrigerant from the evaporator 32 and the supply of high pressure medium at the high pressure port 14 he follows.

This ensures that the opening intervals O and the closing intervals S within the respective switching interval SI have an insignificant effect on the function of the refrigeration system and only minor fluctuations in the temperature of the evaporator 32 lead the refrigeration system according to the invention.

Usually, the durations of the Switching intervals SI for periods of time shorter than about 10 seconds, more preferably shorter than about 2 seconds.

on the other hand are to have sufficient opening intervals To ensure O the switching intervals longer as about 0.02 seconds, better still longer than 0.05 second and preferably longer than 0.1 second.

One preferred operating range provides switching intervals SI whose Duration is between 0.1 and 10 seconds.

In order to ensure such short switching intervals SI is preferably provided that the switching piston 94 together with the valve body 90 and the elastic energy storage 120 have a total natural frequency, which is higher than the maximum switching intervals corresponding frequency SI, so that the switching piston 94 are able to realize the opening intervals O and the closing intervals S substantially instantaneously within the switching intervals SI.

The natural frequencies of the systems are preferably made of control pistons 94 , Valve body 90 and elastic energy storage 120 by a factor of at least 5 or even better at least 10 higher than the frequencies corresponding to the switching intervals SI.

To realize this is suitably provided that the switching piston 94 are made of a lightweight material, such as light metal or plastic, to move small masses.

In a second embodiment of a refrigerant compressor according to the invention, shown in FIG 7 and 8th are the control pistons 94 ' designed as a hollow body in order to achieve the lowest possible mass and thus the highest possible natural frequency.

The solution according to the invention, for example, sees such a switching valve 70 per cylinder bank, so that there is the possibility of the inlet flow for all cylinder units 44 a cylinder bank 42 switch off accordingly.

But it is also conceivable, such a switching valve 70 to arrange so that it is the inlet stream 74 to all cylinder units 44 of the entire refrigerant compressor controls.

In an advantageous solution, the controller controls 130 at least in a lower part-load range, that is, in a range between about 1% and about 30% of the maximum mass flow, all cylinder units 44 with the same switching intervals.

But even in higher part load ranges, for example, in an upper part load range between about 30% and 100% of the maximum mass flow, it is convenient all cylinder units 44 operate with the same switching intervals to avoid balancing problems of the reciprocating compressor, in a complete shutdown of cylinder units 44 arise.

The control 130 is now able to operate the refrigerant compressor 12 in the full load range, the switching valve 70 to control such that the valve body 90 constantly in the inlet opening 92 releasing position is, so that the inlet stream 72 to all cylinder units 44 the respective cylinder bank 42 can flow.

In In this case, the maximum mass flow of refrigerant is compressed to high pressure H.

There is also the possibility in a zero-load range, the switching valve 70 to control so that the valve body 90 constantly in his the inflow opening 92 closing position. In this case, substantially no mass flow of refrigerant is compressed. Only the one through the pressure channel 116 and the pressure supply channel 118 as well as the pressure relief channel 122 flowing mass flow is compressed.

In the partial load range is the controller 130 being able to continuously adjust any part load, by variably setting the duration of the opening interval O and the duration of the closing interval S, which add up to the period of the switching interval SI, in the desired ratio.

there In all partial load ranges, the switching interval SI can be the same.

But it is also conceivable switching interval SI either proportionally or in individual steps depending on the speed of the eccentric shaft 54 and thus the electric motor 55 to vary.

For example the variation of the switching interval SI is such that at less Speed of the electric motor, the switching intervals SI long and at high speed of the electric motor, the switching intervals are shorter.

The advantage of the solution according to the invention is the fact that in the reciprocating compressor, the power consumption is proportional to the mass flow rate and thus at a reduction of the mass flow rate by successive Öff O intervals and closing intervals S in the partial load range, it is also possible to reduce the power consumption of the reciprocating compressor.

In addition, the solution according to the invention provides the possibility of starting the refrigerant compressor 12 by controlling the mass flow rate so that the risks from auskochendem refrigerant are minimized.

Claims (23)

Refrigerant compressor for refrigeration systems comprising at least one cylinder unit ( 44 ), which is a cylinder housing ( 46 ) and in the cylinder housing ( 46 ) oscillating piston ( 48 ), a cylinder head ( 58 ), with one of an inlet stream ( 74 ) of the at least one cylinder unit ( 44 ) through the inlet chamber ( 72 ) and with one of an outlet stream ( 86 ) of the at least one cylinder unit ( 44 ) permeated outlet chamber ( 88 ) and a switching valve ( 70 ) for interrupting the inlet stream ( 74 ) characterized in that a controller ( 130 ) for driving the switching valve ( 70 ) is provided, which for the operation of the refrigerant compressor ( 12 ) in a lower part-load range, the switching valve ( 70 ) in successive, one opening interval (O) and one closing interval (S) of the switching valve ( 70 ) is shorter than a shortest time (Z), after which a temperature (T) of an evaporator ( 32 ) in the working refrigeration system ( 10 ) upon interruption of the inlet stream ( 74 ) has risen by about 10%. Refrigerant compressor according to the preamble of claim 1 or claim 1, characterized in that a controller ( 130 ) for driving the switching valve ( 70 ) is provided, which for the operation of the refrigerant compressor ( 12 ) in a lower part-load range, the switching valve ( 70 ) at successive switching intervals (SI) shorter than about 10 seconds. Refrigerant compressor according to claim 2, characterized in that the switching intervals are shorter as about 2 seconds. Refrigerant compressor according to one of the preceding claims, characterized that the Switching intervals (SI) longer as about 0.02 seconds are. Refrigerant compressor according to claim 4, characterized in that the switching intervals (SI) longer than approximately 0.05 seconds are. Refrigerant compressor according to claim 5, characterized in that the switching intervals (SI) longer than approximately 0.1 seconds are. Refrigerant compressor according to one of the preceding claims, characterized in that the switching intervals (SI) correspond to a switching frequency which is less than a natural frequency of the switching valve (FIG. 70 ). Refrigerant compressor according to claim 7, characterized in that the switching intervals (SI) correspond to a switching frequency which is smaller than a natural frequency of the switching valve by more than a factor of 5 ( 70 ). Refrigerant compressor according to one of the preceding claims, characterized in that the controller ( 130 ) in the lower part load range all cylinder units ( 44 ) operates in the switching intervals (SI). Refrigerant compressor according to claim 9, characterized in that the controller ( 130 ) in the entire partial load range all cylinder units ( 44 ) operates in the switching intervals (SI). Refrigerant compressor according to one of the preceding claims, characterized in that the controller ( 130 ) operates with time constant switching intervals (SI). Refrigerant compressor according to one of the preceding claims, characterized in that the controller ( 130 ) the switching intervals (SI) corresponding to a drive speed of the refrigerant compressor ( 12 ) varies. Refrigerant compressor according to one of the preceding claims, characterized in that the switching valve ( 70 ) is a servo valve. Refrigerant compressor according to claim 13, characterized in that the servo valve ( 70 ) one by one with the pressure in the outlet chamber ( 88 ) contiguous pressure actuatable valve body ( 90 ). Refrigerant compressor according to claim 14, characterized in that the valve body ( 90 ) by an opposite effect of the pressure on the valve body ( 90 ) acting elastic energy storage ( 120 ) is acted upon. Refrigerant compressor according to one of claims 14 or 15, characterized in that the valve body ( 90 ) with one with the pressure in the outlet chamber ( 88 ) and pressure in a switch cylinder housing ( 96 ) guided control piston ( 94 ) is coupled. Refrigerant compressor according to one of claims 14 to 16, characterized in that the switching piston ( 94 ) and the shift cylinder housing ( 96 ) a switching cylinder chamber ( 98 ) and that the pressure in the switching cylinder chamber is controllable. Refrigerant compressor according to one of claims 14 to 17, characterized in that the valve body ( 90 ) and the switching piston form a unit which in the switching cylinder housing ( 96 ) is guided. Refrigerant compressor according to one of claims 13 to 18, characterized in that the servo valve ( 70 ) one from the controller ( 130 ) controllable control valve ( 110 ). Refrigerant compressor according to claim 19, characterized in that the control valve ( 110 ) a connection channel ( 116 . 118 ) between the switching cylinder chamber ( 98 ) and the outlet chamber ( 88 ) opens or closes. Refrigerant compressor according to one of claims 15 to 20, characterized in that the natural frequency of the unit consists of control pistons ( 94 ), Valve body ( 90 ) and elastic energy storage ( 120 ) at least the natural frequency of the switching valve ( 70 ) corresponds. Refrigerant compressor according to one of the claims 14 to 21, characterized in that the switching piston of a Lightweight construction material is made. Refrigerant compressor according to one of claims 14 to 22, characterized in that the actuating piston ( 94 ' ) is designed as a hollow body.