CN117916465A

CN117916465A - Adjusting device for adjusting the pressure and/or temperature of a refrigerant fluid entering a compressor of a refrigeration device, corresponding refrigeration device and method for operating said adjusting device

Info

Publication number: CN117916465A
Application number: CN202280059227.6A
Authority: CN
Inventors: M·阿斯卡尼
Original assignee: Turbine Argo Co ltd
Current assignee: Turbine Argo Co ltd
Priority date: 2021-09-15
Filing date: 2022-09-12
Publication date: 2024-04-19
Also published as: WO2023042051A1; KR20240056756A

Abstract

A regulating device (1) for regulating the pressure and/or temperature of a refrigerant fluid entering a compressor (101) of a refrigeration plant (100) having a closed circuit (C) within which a refrigerant fluid of a flow rate (P) whose pressure and/or temperature must be regulated circulates, a cooling device (102) and an evaporator (103), said regulating device (1) comprising at least one reciprocating compressor (2) equipped with at least one cylinder (7), at least one rod (8), at least one first piston (9 a) integrally constrained to said rod and translatable inside said cylinder, said cylinder (7) being equipped with a first chamber (10) comprising a first port (11) for the suction inflow of said refrigerant fluid of a first flow rate from said evaporator, and a second port (12) for the outflow of a compressed refrigerant fluid of said first flow rate intended to reach said compressor (101) contained in said first chamber (10), said cylinder (7) further comprising a second chamber (20) for the separation of said refrigerant fluid from said first flow rate (2) by means of said first chamber (20) and said first chamber (21), the regulating device (1) further comprising control means (50) for controlling the actuation of the at least one lever (8), adapted to divert the refrigerant fluid of the at least one second flow rate, to control the displacement of the at least one first piston (9 a) and to compress the refrigerant fluid of the first flow rate contained in the first chamber, and to re-enter the refrigerant fluid of the second flow rate during the step of sucking the refrigerant fluid of the first flow rate, during the displacement of the at least one first piston (9 a), the control means (50) comprising a valve (51) equipped with an inlet line (51 a) and an outlet line (51 b) for the second flow rate, and at least one first passage (52 a) passing through the valve, the valve being rotatable so as to assume at least one first radial position (P1) and at least one second radial position (P2) in which the refrigerant fluid of the second flow rate is allowed to enter the closed circuit during the step of sucking the refrigerant fluid of the first flow rate, characterized in that the valve (52 a) is in communication with the at least one second flow rate in the first chamber (20) between the first and the second flow rate (20 a) and the first flow rate of the first flow rate and the second flow rate (20 a) is allowed to pass through the first flow rate, fluid communication between the at least one second chamber (20) and the outlet line (51 b) of the rotary valve (51) is allowed through the at least one passage (52 a) for suction of the refrigerant fluid within the at least one first chamber (10).

Description

Adjusting device for adjusting the pressure and/or temperature of a refrigerant fluid entering a compressor of a refrigeration device, corresponding refrigeration device and method for operating said adjusting device

Technical Field

The present invention relates to a regulating device for regulating the pressure and/or temperature of a refrigerant fluid entering a compressor of a refrigeration apparatus, a corresponding refrigeration apparatus and a method for operating said regulating device. In particular, the device is used for refrigeration equipment operating with a refrigerant fluid of the carbon dioxide type or with similar characteristics.

However, it should be emphasized that the solution object of the present invention is also applicable in the field of power production.

Background

As is well known, refrigeration equipment for refrigerant fluids of the type described above comprises a closed circuit in which the refrigerant fluid flows, and along which a compressor, a refrigerant fluid cooler, an expansion valve and an evaporator are arranged.

It is also known to use one or more secondary economizer branches for refrigerant fluid circulating in a closed loop in order to increase the efficiency of a refrigeration apparatus using carbon dioxide as the refrigerant fluid. It should be noted that, according to known techniques, the secondary economizer branch is fluidly connected on one side to a portion of the main branch of the closed circuit between the cooling device or cooler and the expansion valve, and on the other side to the main compressor. The secondary economizer branch includes an expansion valve and a heat exchanger for exchanging heat with the primary circuit, while the flow from the secondary economizer branch has an intermediate pressure between the maximum and minimum pressures circulating in the circuit of the refrigeration device, i.e. between the fluid pressure at the cooling device and the fluid pressure at the evaporator.

Regardless, refrigeration equipment employing carbon dioxide as the refrigerant fluid is not energy efficient even with one or more secondary economizer branches. In fact, their efficiency is still quite low.

Patent WO2020084545 in the name of the applicant describes a refrigeration apparatus which is a circuit of the above-mentioned type, i.e. comprising at least one economizer branch, and which also has means for regulating the pressure and temperature of the refrigerant fluid entering the main compressor of the apparatus. In practice, the regulating device comprises a reciprocating compressor functionally connected between the evaporator and the main compressor, and means (means) for diverting at least a portion of the refrigerant fluid fraction coming from the secondary economizer branch to control the displacement of the piston of the reciprocating compressor, so as to compress the refrigerant fluid coming from the evaporator and contained in the cylinder of the same reciprocating compressor, and reintroduce this portion of refrigerant fluid fraction into the secondary economizer branch during the step of pumping the refrigerant fluid coming from the evaporator, for the outflow of a portion of refrigerant fluid through the outlet section of the secondary economizer branch; wherein the outlet section of the secondary economizer branch is disposed downstream of the reciprocating compressor. The steering means consist of a piston cylinder keyed to the rod, the displacement of which is instead controlled by a piston in the reciprocating compressor of the adjusting device. In particular, the rod is displaced when the piston reaches an end stop in the reciprocating compressor cylinder. In fact, the cylinder cover is provided with a microswitch which, once pressed by the piston, allows the reciprocating compressor and the steering device to start the next operating cycle.

The reciprocating compressor used in this solution is also called a free piston expander compressor, because the movement of the piston is not controlled by the connecting rod/crank mechanism, but the piston is thus free to move.

The above solution has the advantage of being mechanically very simple, however, on the other hand, it has the potential risk of colliding with the cylinder head. This is why the oscillation frequency of the reciprocating compressor piston is kept low. However, the solution using end stops, such as the above-mentioned cylinders, does not solve the problem of limiting the oscillation frequency of the piston of the reciprocating compressor, and does not allow to remain controlled certain parameters which may be important for the correct operation of the refrigeration system in which the reciprocating compressor is installed.

It is therefore an object of the present invention to provide an adjustment device for a refrigeration apparatus which, in use, does not risk possible mechanical damage to the reciprocating compressor comprised therein due to the piston striking the cylinder cover.

It is a further object of the present invention to provide an adjustment device that allows easier control of the reciprocating compressor present therein.

Finally, it is an object of the present invention to achieve a method that allows for a more efficient adjustment and fine tuning of the adjusting means in a refrigeration appliance.

Disclosure of Invention

These and other objects are achieved by a regulating device for regulating the pressure and/or temperature of a refrigerant fluid entering a compressor of a refrigeration plant having a closed circuit, a cooling device and an evaporator, a flow rate (flow rate) of refrigerant fluid, the pressure and/or temperature of which must be regulated, circulating within said closed circuit, said regulating device comprising at least one reciprocating compressor equipped with at least one cylinder, at least one rod, at least one first piston integrally constrained to said rod and translatable within said cylinder, said cylinder being equipped with a first chamber comprising a first port for receiving a suction inflow of said refrigerant fluid of a first flow rate from said evaporator, said second port for receiving an outflow of compressed refrigerant fluid of said first flow rate in said first chamber and intended to reach said compressor, said cylinder further comprising a second chamber isolated from said first chamber by said first piston and equipped with at least one first piston for receiving said first flow rate of refrigerant fluid, said first port for controlling said flow rate of refrigerant fluid and said first port being adapted to be displaced, said first port being adapted to receive said refrigerant fluid and said flow rate of refrigerant fluid during said first flow rate displacement, during displacement of the at least one first piston, the second flow rate of refrigerant fluid is re-entered into the closed circuit, characterized in that the control device comprises a valve equipped with an inlet line and an outlet line for the second flow rate and at least one first channel through the valve, the valve being a rotatable rotary valve such that at least one first radial position, in which fluid communication between the inlet line to the rotary valve and the at least one second chamber is allowed through the at least one first channel, for inflow of the second flow rate into the second chamber and compression of the first flow rate accommodated in the at least one first chamber, and at least one second radial position, in which fluid communication between the at least one second chamber and the outlet line of the rotary valve is allowed through the at least one channel, for suction of refrigerant fluid within the at least one first chamber.

The device is particularly useful in refrigeration equipment where the refrigerant fluid is carbon dioxide.

This solution allows to solve the problems of the known art described above.

Thanks to this solution, the oscillation frequency of the reciprocating compressor with free piston is directly related to the rotation speed of the rotary valve, as is the case of the claimed compressor. In practice, the rotational speed of the valve is doubled, as is the oscillating frequency of the reciprocating compressor piston. Thus, as the rotational speed of the valve increases, the piston stroke decreases and the flow rate of fluid processed by the reciprocating compressor increases. This means that by means of adjusting the speed of the rotary valve, such as a static inverter, the refrigeration cycle can be optimized to maximize the efficiency or cooling power provided by the system. Furthermore, the possibility of high frequency operation brings significant benefits in terms of the mechanical efficiency of the reciprocating compressors used. In fact, a smaller displacement of the reciprocating compressor and thus a more compact compressor can be used, since the required displacement is inversely proportional to the oscillation frequency of the piston under the same operating conditions. This becomes particularly valuable if we consider that the safety problem caused by small displacements is less, since refrigeration systems involving high pressures (even higher than 100 bar) are involved.

According to a further embodiment of the proposed solution, the reciprocating compressor comprises at least one further piston integrally constrained to the at least one rod and translatable inside the cylinder, wherein the cylinder is equipped with a further first chamber comprising a further first port for inflow of the refrigerant fluid at the first flow rate from the evaporator and a further second port for inflow of the refrigerant fluid contained in the further first chamber, serving as an outflow of compressed refrigerant fluid contained in the further first chamber and intended to reach the first flow rate of the compressor, the cylinder further comprising a further second chamber fluidly isolated from the further first chamber by the further piston and equipped with at least one further third inflow port for the refrigerant fluid at a second flow rate such that the further piston displaces and compresses the refrigerant fluid contained in the further first chamber, the at least one further second chamber being equipped with at least one second rotary valve allowing radial communication between the at least one second chamber and the at least one rotary valve through the at least one second inlet when the further second chamber is in fluid communication with the at least one further rotary valve through the at least one second flow port, an inflow for the second flow rate into the further second chamber and a compression of the first flow rate accommodated in the at least one further first chamber.

This further solution allows a continuous flow with a first flow rate and a second flow rate from the discharge line of the reciprocating compressor and from the outlet line of the rotary valve, respectively.

According to a particular aspect of the invention, the adjustment comprises adjustment means for adjusting the rotational speed of the rotary valve and for changing the switching frequency between the first radial position and the second radial position.

In particular, the regulating means for the rotary valve comprise an electric motor mechanically coupled to the rotary valve for rotation thereof, an inverter adapted to regulate the rotational speed of the electric motor, and a control unit functionally connected to the inverter for controlling the operation thereof.

In fact, based on the information from the control unit, the inverter allows to adjust the speed of the electric motor mechanically connected to the rotary valve.

Furthermore, the regulating device comprises a pressure sensor arranged along the inlet line at the rotary valve, which pressure sensor is functionally connected to the regulating means, in particular the control unit, such that the rotational speed of the valve varies in accordance with the pressure measured by the pressure sensor.

However, as will be described below, in the case where the refrigeration system in which the device is installed has an economizer branch located at the inlet of the rotary valve, the oscillation frequency of the piston is precisely controlled by the pressure of the vapor generated by the economizer (the pressure measurement comes from the pressure sensor described above). In this case, the aim is to keep this pressure from the economizer constant (at the setpoint value), as this has a dual benefit. In fact, on the one hand, maximization in terms of energy efficiency of the refrigeration cycle is achieved, and on the other hand, the risk that the system may become unstable, i.e. that the pressure and temperature of the refrigerant fluid oscillate around the equilibrium value of the refrigerant is avoided.

In particular, in case the pressure along the inlet line of the rotary valve of the refrigerant fluid increases with respect to the setpoint pressure, the control unit controls the increase of the rotational speed of the rotary valve (and therefore of the electric motor to which the valve is integrally constrained) by means of the inverter, resulting in a decrease of the pressure of the refrigerant fluid of the second flow rate. When the pressure of the refrigerant fluid entering the rotary valve drops too low compared to the setpoint value, the control unit controls the reduction of the rotational speed of the rotary valve (and thus of the electric motor to which the valve is integrally constrained) by the inverter, resulting in an increase of the pressure of the refrigerant fluid of the second flow rate. This allows the determined setpoint pressure to be pursued in order to achieve a specific refrigeration level of the refrigeration appliance in which the regulating device is installed.

Furthermore, the regulating means may comprise a pressure sensor and/or a temperature sensor, which are then arranged along the inlet line of the reciprocating compressor and are functionally connected to the regulating means, in particular to the control unit, such that the rotational speed of the valve varies in accordance with the pressure and/or temperature measured by the pressure sensor and/or the temperature sensor.

In this case too, the control of the rotational speed of the rotary valve is effected by means of the pressure and/or temperature values of the fluid at the evaporator outlet of the refrigeration appliance in which the regulating device is installed, before it enters the reciprocating compressor.

Thus, in case the pressure and/or temperature value of the refrigerant fluid of the first flow rate reaching the inlet line of the reciprocating compressor varies with respect to the setpoint data, the control unit, through the inverter, rotates the rotation speed of the valve (and therefore of the electric motor to which the valve is integrally constrained) up/down, resulting in an increase and/or a decrease of the pressure of the refrigerant fluid of the first flow rate.

Furthermore, in a further embodiment of the present invention, the adjusting means may comprise a position sensor for determining the position of the first piston and/or the further first piston of the reciprocating compressor along the at least one cylinder for determining the position reached by the first piston and/or the further piston. The position sensor is functionally connected to the adjustment device such that the rotational speed of the valve varies in accordance with information obtained from the at least one position sensor. In practice, the control unit receives input information obtained from the at least one position sensor and controls the variation of the rotational speed of the valve in accordance with the information obtained from the at least one position sensor.

In particular, the position sensor comprises at least one proximity sensor.

This obviously allows fine control of the position that the piston must reach in order for it to function optimally. In fact, if the piston reaches the position in which the position sensor is located during its stroke, the control unit controls the rotational speed of the rotary valve to increase, so that at some point there will be a decrease in the piston stroke, so that the proximity sensor will no longer be able to "sense" the presence of the piston. At this time, the control unit must control the rotation speed of the rotary valve to decrease in order to increase the stroke of the piston, thus reaching the position of the pressure sensor again. In practice, the position is tracked continuously along the cylinder where the position sensor is arranged in a sense.

As a result, the piston does not oscillate at a constant frequency, but rather at a "slightly variable" frequency, the average of which is the frequency that maximizes the stroke.

According to a first embodiment of the refrigeration device, it comprises: closed circuit of a flow rate of a refrigerant fluid circulating therein, a compressor, a cooling device, an evaporator from which a first flow rate flows, at least one expansion valve and at least one regulating device according to one or more of claims 1 to 8, wherein the closed circuit further comprises at least one economizer branch along which a second flow rate of refrigerant fluid flows, the at least one economizer branch fluidly connecting a section of the closed circuit comprised between the cooling device and the expansion valve with a section comprised between the evaporator and the compressor, and wherein the reciprocating compressor of the regulating device has the first flow rate leaving the evaporator at an inlet, the rotary valve has the second flow rate circulating along the economizer branch at an inlet, wherein the outlet line of the rotary valve is connected to the inlet line of the reciprocating compressor downstream of the rotary valve.

As described above, in the present embodiment, the oscillation frequency of the piston can be controlled by the pressure of the vapor generated by the economizer. In this case, the aim is to keep this pressure from the economizer constant (at the setpoint value), as this has a dual benefit. In fact, on the one hand, maximization in terms of energy efficiency of the refrigeration cycle is achieved, and on the other hand, the risk that the system may become unstable, i.e. that the pressure and temperature of the refrigerant fluid oscillate around the equilibrium value of the refrigerant is avoided.

According to a second embodiment of the apparatus, comprising a closed circuit in which a flow rate of refrigerant fluid circulates, a compressor, a cooling device, an evaporator and a regulating device according to one or more of claims 1 to 8, the reciprocating compressor of the regulating device having the first flow rate exiting from the evaporator at an inlet and the rotary valve having a flow rate exiting from the cooling device at an inlet, the outlet line of the rotary valve being connected to the evaporator.

Specifically, in the latter embodiment, the flow rate of the refrigerant fluid circulating in the closed circuit is the same as the first flow rate of the refrigerant fluid and the second flow rate of the refrigerant fluid. Furthermore, this embodiment has no expansion valve or metering valve.

Finally, these objects are also achieved by a method for operating an adjustment device according to one or more of claims 1 to 8, comprising the steps of:

Step a) allowing an inflow of a first flow rate of a refrigerant fluid in the at least one first chamber of the cylinder of the reciprocating compressor;

Step b) allowing an inflow of a second flow rate of refrigerant fluid in the at least one second chamber of the cylinder of the reciprocating compressor to control the displacement of the at least one first piston and compress the first flow rate of refrigerant fluid contained in the first chamber;

Step c) re-entering the second flow rate of refrigerant fluid into the closed circuit during displacement of the at least one first piston during the step of pumping the first flow rate of refrigerant fluid during the step a);

Characterized in that said step c) comprises: step c 1) rotating the rotary valve to a first position to assume at least one first radial position in which fluid communication between the inlet line to the rotary valve and the at least one second chamber is allowed through the at least one first passage for inflow of the second flow rate into the second chamber and compression of the first flow rate contained in the at least one first chamber; and step c 2) rotating the rotary valve to the second radial position in which fluid communication between the at least one second chamber and the outlet line of the rotary valve is permitted through the at least one passage for suction of refrigerant fluid within the at least one first chamber.

Furthermore, the method comprises a step d) of adjusting the switching speed of the rotary valve from the first radial position to the second radial position depending on the pressure and temperature of the refrigerant fluid entering the first chamber of the reciprocating compressor or depending on the position of the at least one first piston within the cylinder for operating the adjusting device depending on the pressure of the refrigerant fluid entering the rotary valve.

Drawings

Specific embodiments of the invention will now be described, by way of non-limiting example only, with reference to the accompanying drawings, in which:

FIG. 1 is a schematic view of a refrigeration appliance in which a regulating device according to the invention is installed;

Fig. 2A is a schematic longitudinal sectional view of the adjusting device according to the invention at least when the rotary valve is in its first angular position;

FIG. 2B is a schematic longitudinal sectional view of the regulating device of FIG. 2A with the rotary valve in its second angular position;

fig. 3A is a schematic longitudinal sectional view of an adjusting device according to a second embodiment of the invention, at least when the rotary valve is in its first angular position;

FIG. 3B is a schematic longitudinal sectional view of the regulating device of FIG. 3A with the rotary valve in its second angular position;

FIG. 4 is a schematic view of a further refrigeration apparatus including a regulating device according to the present invention;

Figure 5 is a schematic diagram of a third refrigeration appliance including a regulating device according to the invention;

fig. 6 is a longitudinal section through a third embodiment of an adjusting device according to the invention.

Detailed Description

With particular reference to these figures, 1 indicates a universal regulating device according to the invention.

In particular, fig. 1 shows a generic refrigeration apparatus 100 on which an adjusting device 1 is mounted.

Specifically, the refrigeration apparatus 100 includes a closed circuit C in which a flow rate P of refrigerant fluid circulates, a compressor 101, a cooling device 102, an evaporator 103 from which a first flow rate X1 exits, and at least one expansion valve 104. The compressor 101 is of an alternating type, however, in another embodiment, the compressor 101 may be of another type without thereby departing from the scope of the present invention. The closed loop C also includes an economizer branch 105 along which the refrigerant fluid of the second flow rate X2 flows. The economizer branch 105 is fluidly connected to include a closed circuit between the cooling device 102 and the expansion valve 104 and a closed circuit between the evaporator 104 and the compressor 101. The economizer branch 105 includes a heat exchanger 106 and an expansion valve 107 in a known manner. Along the economizer branch 105, the pressure of the refrigerant fluid is lower than the pressure at the outlet of the cooling device 102. On the other hand, the pressure of the refrigerant fluid leaving the evaporator 103 is lower than the pressure of the refrigerant fluid at the second flow rate X2. The secondary branch 105 has an inlet manifold 105a of refrigerant fluid at a flow rate X2 within the secondary branch 105 and an outlet manifold 105b connected to the closed circuit C upstream of the compressor 101.

Fig. 2A shows a regulating device 1 for regulating the pressure and temperature of a refrigerant fluid entering a compressor 101 of a refrigeration apparatus 100.

According to a first embodiment of the invention, the regulating device 1 comprises a reciprocating compressor 2 equipped with a cylinder 7, a rod 8, a first piston 9a integrally constrained to the rod 8 and translatable inside the cylinder 7. The cylinder 7 is equipped with a first chamber 10, the first chamber 10 comprising a first port 11 for sucking in a suction inflow of a refrigerant fluid of a first flow rate X1 from the evaporator 103 and a second port 12 for an outflow of a compressed refrigerant fluid of a first flow rate X1 contained in the first chamber 10 and intended to reach the compressor 101 of the device 100. The cylinder 7 further comprises a second chamber 20, the second chamber 20 being fluidly isolated from the first chamber 10 by a first piston 9a and being equipped with a third port 21 for inflow of the refrigerant fluid of a second flow rate X2, so as to displace the piston 9a and compress the refrigerant fluid contained in the first chamber 10. It should be noted that while it will also be apparent from the description of the apparatus 100' and 100 "of fig. 4 and 5, the refrigerant fluid of the first flow rate X1 and the refrigerant fluid of the second flow rate X2 may also be distinct, i.e. different, or the same, without thereby departing from the scope of the present invention.

The regulating device 1 further comprises control means 50 for controlling the actuation of the lever 8, adapted to divert the refrigerant fluid of the second flow rate X2, to control the displacement of the first piston 9a and to compress the refrigerant fluid of the first flow rate X1 contained in the first chamber 10, and to re-enter the refrigerant fluid of the second flow rate X2 into the closed circuit C during the displacement of the first piston 9a during the step of sucking the refrigerant fluid of the first flow rate X1. The control means 50 comprise a valve 51, the valve 51 being provided with an inlet line 51a and an outlet line 51b for the second flow rate X2, and a first passage 52a through the same valve 51. In addition, the valve 51 is rotatable to assume a first radial position P1 in which fluid communication between the inlet line 51a to the rotary valve 51 and the second chamber 20 for inflow of the second flow rate X2 to the second chamber 20 is allowed through the first passage 52a and simultaneously compression of the first flow rate X1 contained in the first chamber 10, and a second radial position P2 in which fluid communication between the second chamber 20 and the outlet line 51b of the rotary valve 51 is allowed through the first passage 52a for suction of the refrigerant fluid within the first chamber 10.

According to the above, the outlet line 51b of the rotary valve 51 is connected downstream of the reciprocating compressor 2 and upstream of the compressor 101. In particular, the outlet line 51b is connected to the manifold 105b of the economizer branch 105.

The rotary valve 51 has a circular cross section and the passages 52a are formed in the body of the same rotary valve 51.

Indeed, the rotary valve 51 is allowed to rotate at a variable speed in order to also control any possible and undesired increase/decrease of the pressure of the refrigerant fluid of the second flow rate X2 during transients. In fact, therefore, the oscillation speed of the piston 9a of the reciprocating compressor 2 is no longer dependent on the same piston, but on the rotation speed of the rotary valve 51, i.e. its rotation frequency. However, the possibility of varying the speed of the rotary valve 51 and thus of switching the valve from the first position P1 to the second position P2 also allows to control the maximum oscillation of the piston 9a and thus to prevent any possible excessive stroke of the piston 9a with undesired impacts on the cylinder head of the reciprocating compressor 2.

Fig. 2B shows the position reached by the piston 9B when the rotary valve 51 has been moved from its first position P1 to its second position P2.

In a known manner, a suction valve 14 and a relief valve 15 are respectively combined with the ports 11, 12 of the reciprocating compressor 2. These valves 14, 15 open and/or close in synchronism with the travel of the rod 8, with the cyclically having a step of sucking the fluid into the first chamber 10 and a step of compressing and then releasing the same refrigerant fluid contained in the first chamber 10. In practice, during the suction step of the reciprocating compressor 2, i.e. when the rotary valve 51 is in its second position P2, the first port 11 allows the first flow rate X1 inside the first chamber 10 (therefore the suction valve 14 is open), while the second port 12 prevents the outflow of refrigerant fluid from the first chamber 10 (therefore the relief valve 15 is closed).

In this step, the outflow of the second flow rate X2 takes place from the second chamber 20 through the third port 21.

Once the pumping step has been completed, when the piston 9a therefore reaches its rearmost position, the suction valve 14 is closed, the rotary valve 51 assumes its first position P1 and will be at a pressure greater than the pressure of the fluid contained in the first chamber 10 so that the second flow rate X2 of the fluid compressed starts to enter the second chamber 20. After a certain stroke of the piston 9a, the release valve 15 opens, thus allowing the first flow rate X1 to flow along the release line 2 b. At this time, the release valve 15 is closed, the suction valve 14 is opened, and simultaneously the rotary valve 51 is displaced to its second position P2 to restart the cycle again. The speed between the suction step and the compression step of the reciprocating compressor 2 is clearly controlled by the switching speed of the rotary valve 51.

According to the embodiments described herein, the adjusting device 1 comprises means 53 for adjusting the rotational speed of the rotary valve 51 and changing the switching frequency between the first radial position P1 and the second radial position P2.

These adjusting means include in particular: an electric motor 55 mechanically coupled to said rotary valve 51 for rotation thereof, an inverter 56 adapted to regulate the rotational speed of said electric motor, and a control unit 57 functionally connected to the inverter 56 for controlling the operation thereof, so as to regulate the rotational speed of the rotary valve 51 and the variation of the switching frequency between the first radial position P1 and the second radial position P2 assumed by the rotary valve 51.

In particular, in fig. 2A and 2B, the regulating device 1 comprises a pressure sensor 58 arranged along the inlet line 51a to the rotary valve 51. The pressure sensor 58 is functionally connected to the regulating means 53, in particular to the control unit 57, so that the rotational speed of the rotary valve 51 varies in accordance with the pressure measured by the pressure sensor.

This allows the speed of the rotary valve 51 to be varied, for example to maintain the pressure of the fluid of the second flow rate X2 circulating in the economizer branch 105 substantially constant. In fact, in case the pressure along the inlet line of the rotary valve 51 of the refrigerant fluid increases with respect to the setpoint pressure, the control unit 57 controls, through the inverter 56, the increase of the rotation speed of the rotary valve 51 (and therefore of the electric motor 55 to which the rotary valve 51 is integrally constrained), resulting in a decrease of the pressure of the refrigerant fluid of the second flow rate X2. When the pressure of the refrigerant fluid entering the rotary valve 51 drops too low compared to the predetermined setpoint value, the control unit 57 controls the decrease in rotational speed of the rotary valve 51 (and thus the electric motor 55 to which the rotary valve 51 is integrally constrained) through the inverter 56, resulting in an increase in the pressure of the refrigerant fluid at the second flow rate X2. This allows the determined setpoint pressure to be pursued in order to achieve a specific refrigeration level of the refrigeration appliance 100 in which the regulating device is installed.

In this case, the aim is to keep the fluid pressure of the second flow rate X2 from the economizer 105 constant (at the set point value), as this has a dual benefit. In fact, on the one hand, maximization in terms of energy efficiency of the refrigeration cycle is achieved, and on the other hand, the risk that the system 100 may become unstable, i.e. that the pressure and temperature of the refrigerant fluid oscillate around the equilibrium value of the refrigerant is avoided.

In other embodiments, the device 1 comprises a pressure sensor 59 and a temperature sensor 60, which are arranged along the inlet line 2a of the reciprocating compressor 2 and are functionally connected to the aforementioned control unit 57. In this embodiment, the rotational speed of rotary valve 51 is controlled by the temperature and pressure conditions of the refrigerant fluid from evaporator 103. In practice, the system operates to optimize the performance of the evaporator 103.

According to a further embodiment of the invention illustrated in fig. 3A and 3B, the reciprocating compressor 2 comprises a further piston 9B, the further piston 9B being integrally constrained to the rod 8 at a position opposite to the piston 9a and translatable inside the cylinder 7. The cylinder 7 is thus equipped with a further first chamber 10a, the further first chamber 10a comprising a further first port 11a for inflow of the refrigerant fluid of the first flow rate X1 from the evaporator 103 and a further second port 12a for outflow of the compressed refrigerant fluid X1 contained in the further first chamber 10a and intended to reach the first flow rate of the compressor 101. The cylinder 7 further comprises a further second chamber 20a, which further second chamber 20a is fluidly isolated from the further first chamber 10a by a further piston 9b and is provided with a further third port 21a for inflow of the refrigerant fluid of the second flow rate X2 for displacing the further piston 9b and compressing the refrigerant fluid contained in the further first chamber 10. The rotary valve 51 is further provided with a second passage 52b such that, at least when the rotary valve 51 assumes the first radial position P1, fluid communication between the further second chamber 20a and the outlet line 51b of the rotary valve 51 is allowed through the second passage 52b for suction of the refrigerant fluid within the further first chamber 10a, and, at least when the rotary valve 51 assumes the second radial position P2, fluid communication between the inlet line 51a of the rotary valve 51 and the further second chamber 20a is allowed through the second passage 52b for inflow of the refrigerant fluid of the second flow rate X2 to the further second chamber 20a, and compression of the first flow rate accommodated in the further first chamber 10 a.

This allows to have a continuous outlet flow rate from the reciprocating compressor 2, since in both the first radial position P1 and the second radial position P2 of the rotary valve 51 there is always a first flow rate X1 and a second flow rate X2 leaving the reciprocating compressor 2 to the compressor 101 of the refrigeration device 100.

Also in this case, in a known manner, a suction valve 14a and a relief valve 15a are respectively combined with the ports 11a, 12a of the reciprocating compressor 2. These valves 14a, 15a open and/or close in synchronism with the travel of the rod 8, cyclically having the step of sucking the fluid into the further first chamber 10a and the step of compressing and then releasing the same refrigerant fluid contained in the further first chamber 10a. In practice, during the suction step of the reciprocating compressor 2 within the further first chamber 10a, i.e. when the rotary valve 51 is in its first position P1, during which compression of the fluid present in the further first chamber 10 takes place, the further first port 11a is open for the passage of the first flow rate X1 within the further first chamber 10a (hence the suction valve 14a is open), while the further second port 12a prevents the outflow of the refrigerant fluid from the further first chamber 10.

In this step, a second flow rate X2 occurs from the outflow of the further second chamber 20 through the further third port 21 a.

Once the pumping step has been completed, when the piston 9b thus reaches its rearmost position, the further suction valve 14a is closed and the further release valve 15a is still closed, the rotary valve 51 assumes its second position P2 and will be at a pressure greater than the pressure of the fluid contained in the further first chamber 10a so that the second flow rate X2 of the fluid starts to enter the further second chamber 20. After a certain stroke of the piston 9b, the relief valve 15a opens, thus allowing the first flow rate X1 to flow along the relief line 2 b. At this time, the additional relief valve 15a is closed and the additional suction valve 14a is opened while the rotary valve 51 is displaced to its first position P1 to restart the cycle again. The speed between the suction step and the compression step of the reciprocating compressor 2 is clearly controlled by the switching speed of the rotary valve 51.

However, in this embodiment, because of the presence of the two passages 52a and 52b, a switch from the first position P1 to the second position P2 occurs each time the rotary valve 51 rotates by 90 °.

Also in this embodiment, the rotary valve 51 is connected to the electric motor 55, the inverter 56 and the control unit 57 for adjusting the rotational speed of the rotary valve 51 and changing the switching frequency of P2 between the first position P1 and the second radial position.

Furthermore, as in the first embodiment, also in this embodiment, the device 1 comprises a pressure sensor 58 arranged along the inlet line 51a of the rotary valve 51. The pressure sensor 58 is functionally connected to the control unit 57 so that the speed of the rotary valve 51 (and therefore of the motor 7 mechanically connected thereto) is regulated as a function of the pressure of the refrigerant fluid detected by the sensor 58.

In fig. 6, a device 1 is shown, which is very similar to the device of the second embodiment, although in an extremely simplified manner. It differs from the latter in that it comprises a position sensor 61 for determining the position of the first piston 9a of the reciprocating compressor 2 and therefore of the further piston 9b along the cylinder 7 (since they are integrally and rigidly connected to the rod 8) for determining the position reached by the first piston 9a and therefore by the further piston 9 b. Specifically, the position sensor 61 includes a proximity sensor. The position of the piston 9a is continuously transmitted to the control unit 57 so that the motor 55 (not shown here, but present) controlling the rotational speed of the valve 51 pursues the correct position maintained by the pistons 9a, 9b, thus avoiding possible impacts of the pistons 9a and 9b inside the cylinder 7.

In particular, the position that the piston 9a (and thus 9 b) must reach can be carefully controlled to perform its optimal function. In fact, if the piston 9a reaches the position in which the position sensor 61 is located during its stroke, the control unit 57 controls the rotational speed of the rotary valve 51 to increase, so that at some point there will be a decrease in the piston stroke 9a, so that the proximity sensor 61 will no longer be able to "sense" the presence of the piston 9 a. At this time, the control unit 57 must control the rotation speed of the rotary valve 51 to decrease in order to increase the stroke of the piston 9a, thus reaching the position of the pressure sensor 61 again. In practice, the position is tracked continuously along the cylinder 7 where the position sensor 61 is arranged in a sense.

As a result, the piston 9a does not oscillate at a constant frequency, but at a "slightly variable" frequency, the average of which is the frequency that maximizes the stroke.

This embodiment is also obviously reproducible from the first embodiment described above, in which only one piston 9a is present instead of the two pistons 9a and 9b.

Fig. 4 shows a second example of a device 100', wherein the adjusting means 1 is present in its first embodiment, or alternatively in its second embodiment.

In particular, the refrigeration apparatus 100' comprises a closed circuit C in which a refrigerant fluid of a flow rate P circulates, a compressor 101, a cooling device 102, an evaporator 103 from which a first flow rate X1 flows, at least one expansion valve 104 and at least one regulating device 1 of the above-mentioned type or in any case according to one or more of claims 1 to 8. The compressor 101 is of the reciprocating type, however, in another embodiment, the compressor 101 may be of another type without thereby departing from the scope of the present invention. The closed loop C also includes an economizer branch 105 along which the refrigerant fluid of the second flow rate X2 flows. The economizer branch 105 is fluidly connected to include a closed circuit between the cooling device 102 and the expansion valve 104 and a closed circuit between the evaporator 104 and the compressor 101. The reciprocating compressor 2 of the regulating device 1 has a first flow rate X1 leaving the evaporator 104 at the inlet. The rotary valve 51 (only schematically shown in fig. 4) has the aforementioned second flow rate X2 circulating along the economizer branch 105 at the inlet, wherein said outlet line 51b of the rotary valve 51 is connected to the inlet line of the compressor 101 downstream of the reciprocating compressor 2. The economizer branch 105 includes a heat exchanger 106 and an isolation tank (or also referred to as a "flash tank") for containing refrigerant 107. Downstream of the heat exchanger 106, before flowing into the tank 107, there is a valve 120 along the line for regulating the pressure of the refrigerant fluid entering the separator tank 120. Along the economizer branch 105, the pressure of the refrigerant fluid is equal to the pressure present in the isolation tank 107, but lower than the pressure at the outlet of the cooling device 102.

The apparatus 100' further includes a second economizer branch 110 along which a further flow rate X3 of refrigerant fluid flows. The second economizer branch 110 comprises in a known manner a further expansion valve 111 and a heat exchanger 112. The further economizer branch 110 fluid connection comprises a closed circuit C between the inlet of the economizer branch 105 and the expansion valve 104 and a closed circuit between the reciprocating compressor 2 and the compressor 101.

In this embodiment, the regulating device 1 comprises a pressure sensor 58 arranged along the inlet line 51a to the rotary valve 51, thus along the economizer branch 105 along which the second flow rate X2 flows. The pressure sensor 58 is functionally connected to the control unit 57. This allows to vary the speed of the rotary valve 51 and thus also the pressure of the flow rate leaving the reciprocating compressor 2. An outlet line 51b of the rotary valve 51 is connected downstream of the reciprocating compressor 2 and upstream of the compressor 101. In particular, the outlet line 51b is connected to the closed circuit upstream of the outlet line of the further economizer branch 110.

In fig. 5, a further device 100″ is shown, in which the adjusting device 1 according to the invention is used.

The refrigeration device 100 "comprises a closed circuit C in which a flow rate P of refrigerant fluid circulates, a compressor 101, a cooling device 102, an evaporator 103 and a regulating device according to one of the above embodiments and in any case according to one or more of claims 1 to 8. The reciprocating compressor 2 of the regulating device 1 has a first flow rate X1 leaving the evaporator 103 at the inlet and the rotary valve 51 has a flow rate X2 leaving the refrigerating device 102 at the inlet, the outlet line 51b of the rotary valve 51 being connected to the evaporator 103. In practice, according to this configuration, the flow rate P of the refrigerant fluid circulating in the closed circuit C is identical to the first flow rate X1 of the refrigerant fluid and the second flow rate X2 of the refrigerant fluid. The device 100 "has no expansion valve and thus the thermodynamic conditions to be achieved by means of such a valve in the device shown in fig. 4 are achieved in the second chamber 20 and/or in the further second chamber 20' (in case of using the second embodiment of the invention).

In this embodiment, the regulating device 1 comprises a pressure sensor 59 and a temperature sensor 60, which are arranged along the inlet line 2a of the reciprocating compressor 2 and are functionally connected to the control unit 57 downstream of the evaporator 103.

In this way, the adjustment of the switching speed of the rotary valve 51 is based on the pressure and temperature parameters of the fluid leaving the evaporator 103. Thus, the apparatus 100 "is optimized to achieve the best possible performance at the evaporator 103.

The adjusting device 1 according to the first embodiment of the invention operates according to a specific method. The method is equally applicable to the device 1 according to the second embodiment of the invention.

The method for operating the adjusting device 1 comprises the following steps:

Step a) allows an inflow of a first flow rate X1 of refrigerant fluid inside the first chamber 10 of the cylinder 7 of the reciprocating compressor 2;

step b) allows an inflow of a second flow rate X2 of refrigerant fluid inside the second chamber 20 of the cylinder of the reciprocating compressor 2 to control the displacement of the first piston 9a and to compress a first flow rate X1 of refrigerant fluid contained in said first chamber 10;

Step C) during the step of sucking the first flow rate of refrigerant fluid during said step a), re-entering the closed circuit C with a second flow rate X2 of refrigerant fluid during the displacement of the first piston 9 a;

Wherein step c) comprises: step c 1), rotating the rotary valve 51 to a first position P1 to assume at least one first radial position P1 in which fluid communication between the inlet line 51a to the rotary valve and the second chamber 20 is allowed through the passage 52a for the inflow of the second flow rate X2 into the second chamber 20 and the compression of the first flow rate X1 contained in the first chamber 10; and step c 2) rotating the rotary valve 51 to a second radial position P2, in which second radial position P2 fluid communication between the second chamber 20 and the outlet line 51b of the rotary valve 51 is allowed through the passage 52a for suction of the refrigerant fluid inside the first chamber 10.

Furthermore, the method comprises a step d) of adjusting the switching speed of the rotary valve 51 from the first radial position P1 to the second radial position P2, depending on the pressure of the refrigerant fluid entering the rotary valve 51, or depending on the pressure and temperature of the refrigerant fluid entering the first chamber 10 of the reciprocating compressor 2, or depending on the position reached by the first piston 9a of the reciprocating compressor 2 inside the cylinder 7.

Claims

1. A regulating device (1) for regulating the pressure and/or temperature of a refrigerant fluid entering a compressor (101) of a refrigeration plant (100), said refrigeration plant having a closed circuit (C) in which a refrigerant fluid of a flow rate (P) whose pressure and/or temperature must be regulated circulates, a cooling device (102) and an evaporator (103), said regulating device (1) comprising at least one reciprocating compressor (2) equipped with at least one cylinder (7), at least one rod (8), at least one first piston (9 a) which is integrally constrained to said rod and which is able to translate inside said cylinder, said cylinder (7) being equipped with a first chamber (10) comprising a first port (11) for the suction flow rate of said refrigerant fluid from a first of said evaporator inflow, said second port being for the reception of said flow rate of said refrigerant fluid in said first chamber (10) and intended to reach said compressor (101), said second chamber (7) being equipped with a second port (20) for the separation of said refrigerant fluid from said first inflow (2) by means of said first chamber (7) and said second port (20), so as to displace the piston and compress the refrigerant fluid contained in the first chamber (10), the regulating device (1) further comprising control means (50) for controlling the actuation of the at least one rod (8), adapted to divert the refrigerant fluid of the at least one second flow rate, for controlling the displacement of the at least one first piston (9 a) and compressing the refrigerant fluid of the first flow rate contained in the first chamber, and adapted to, during the step of sucking the refrigerant fluid of the first flow rate, during the displacement of the at least one first piston (9 a), re-enter the closed circuit with the refrigerant fluid of the second flow rate, characterized in that the control means (50) comprise a valve (51) equipped with an inlet line (51 a) and an outlet line (51 b) for the second flow rate, and at least one first channel (52 a) passing through the valve, the valve being a rotary valve so as to present at least one first position (P1) and at least one second position (P) in radial communication with the at least one first channel (20 a) in the first flow rate (20) and the first flow rate (20 a) in the radial direction, the first position (P) being allowed to enter the closed circuit, in the second radial position, fluid communication between the at least one second chamber (20) and the outlet line (51 b) of the rotary valve (51) is allowed through the at least one passage (52 a) for suction of refrigerant fluid within the at least one first chamber (10).

2. Device according to claim 1, characterized in that the reciprocating compressor (2) comprises at least one further piston (9 b) integrally constrained to the at least one rod (8) and translatable inside the cylinder (7), wherein the cylinder (7) is equipped with a further first chamber (10 a) comprising a further first port (11 a) for inflow of the refrigerant fluid from the evaporator and a further second port (12 a) for at least one of the first ports (21 a) for fluid isolation from the further first chamber (10 a) and intended to reach the first flow rate of the compressor (101), the further second chamber (7) further comprising a further second chamber (20 a) for fluid isolation from the further first chamber (10 a) by the further piston (9 b) and equipped with at least one further second port (12 a) for fluid displacement of the further first port (52) in the radial direction of the first flow rate of refrigerant fluid contained in the further first chamber (10 a) and intended to reach the first flow rate of the rotary valve (101), -allowing fluid communication between the at least one further second chamber (20 a) and the outlet line of the rotary valve through the at least one second passage (52 b) for suction of refrigerant fluid within the at least one further first chamber (10 a), and-allowing fluid communication between the inlet line (51 a) of the rotary valve and the at least one further second chamber (20 a) through the at least one second passage (52 b) for inflow of the second flow rate into the further second chamber (20 a) and compression of the first flow rate contained in the at least one further first chamber (10 a) at least when the rotary valve assumes the second radial position (P2).

3. Device according to claim 1 or 2, characterized by comprising adjustment means (53) for adjusting the rotational speed of the rotary valve (51) and for changing the switching frequency between the first radial position (P1) and the second radial position (P2).

4. A device according to claim 3, characterized in that the adjustment means (53) for the rotary valve (51) comprise an electric motor (55) mechanically coupled to the rotary valve for rotation thereof, an inverter (56) adapted to adjust the rotational speed of the electric motor, and a control unit (57) functionally connected to the inverter for controlling the operation thereof.

5. Device according to claim 3 or 4, characterized by comprising a pressure sensor (58) arranged along the inlet line (51 a) of the rotary valve, which pressure sensor is functionally connected to the control unit (57) such that the rotational speed of the valve varies in accordance with the pressure measured by the pressure sensor.

6. Device according to at least claim 3 or 4, characterized by comprising a pressure sensor (59) and/or a temperature sensor (60) arranged along the inlet line (2 a) of the reciprocating compressor (2), which pressure sensor and/or temperature sensor are functionally connected to the control unit (57) so that the rotational speed of the valve varies depending on the pressure and/or temperature measured by the pressure sensor and/or by the temperature sensor.

7. Device according to one or more of claims 1 to 4, characterized in that it comprises at least one position sensor (61) for determining the position of the first piston of the reciprocating compressor and/or of the further first piston along the at least one cylinder to determine the position reached by the first piston and/or of the further piston, said position sensor being functionally connected to the adjustment device so that the rotation speed of the valve varies according to the information obtained from said at least one position.

8. The device according to claim 7, characterized in that the position sensor (61) comprises at least one proximity sensor.

9. Refrigeration device (100, 100'), comprising: closed circuit (C) with a flow rate (P) of refrigerant fluid circulating therein, a compressor (101), a cooling device (102), an evaporator (103) from which a first flow rate flows, at least one expansion valve (104) and at least one regulating device according to one or more of claims 1 to 8, wherein the closed circuit further comprises at least one economizer branch (105) along which a second flow rate of refrigerant fluid flows, said at least one economizer branch being fluidly connected a section of the closed circuit comprised between the cooling device and the expansion valve with a section comprised between the evaporator (103) and the compressor (101), and wherein the reciprocating compressor of the regulating device (1) has the first flow rate leaving the evaporator at an inlet, the rotary valve has the second flow rate circulating along the economizer branch (105) at an inlet, wherein the outlet of the rotary valve is connected to the reciprocating compressor (2) inlet of the pipeline downstream of the compressor.

10. Refrigeration appliance (100 ") comprising a closed circuit (C) in which a flow rate (P) of refrigerant fluid circulates, a compressor (101), a cooling device (102), an evaporator (103) and a regulating device according to one or more of claims 1 to 8, the reciprocating compressor (2) of the regulating device having the first flow rate exiting from the evaporator at an inlet and the rotary valve having the flow rate exiting from the cooling device (102) at an inlet, the outlet line of the rotary valve being connected to the evaporator.

11. The refrigeration appliance (200) of claim 10, wherein the flow rate of the refrigerant fluid circulating within the closed loop is the same as the first flow rate of refrigerant fluid and the second flow rate of refrigerant fluid.

12. Method for operating an adjusting device (1) according to one or more of claims 1 to 8, the method comprising the steps of:

Step a) allows an inflow of a first flow rate of refrigerant fluid inside the at least one first chamber (10) of the cylinder (7) of the reciprocating compressor (2);

Step b) allows an inflow of a second flow rate of refrigerant fluid inside the at least one second chamber (20) of the cylinder of the reciprocating compressor (2) to control the displacement of the at least one first piston (9 a) and to compress the first flow rate of refrigerant fluid contained in the first chamber (10);

Step c) re-entering the closed circuit during displacement of the at least one first piston (9 a) during the step of sucking the first flow rate of refrigerant fluid during the step a);

Characterized in that said step c) comprises: step c 1) rotating the rotary valve (51) to a first position to assume at least one first radial position (P1) in which fluid communication between the inlet line (51 a) to the rotary valve (51) and the at least one second chamber (20) is allowed through the at least one first passage (52 a), an inflow for the second flow rate (X2) into the second chamber (20) and a compression of the first flow rate contained in the at least one first chamber (10); and a step c 2) of rotating the rotary valve to the second radial position (P2) in which fluid communication between the at least one second chamber (20) and the outlet line (51 b) of the rotary valve (51) is allowed through the at least one passage (52 a) for suction of the refrigerant fluid within the at least one first chamber (10).

13. A method according to claim 12, characterized by comprising a step d) of adjusting the switching speed of the rotary valve (51) from the first radial position to the second radial position in dependence of the pressure and/or temperature of the refrigerant fluid entering the first chamber of the reciprocating compressor or in dependence of the position reached by the at least one first piston within the cylinder (7) of the reciprocating compressor (2) for operating the adjusting device (1) in dependence of the pressure of the refrigerant fluid entering the rotary valve.