Method for actuating semi-commanded valve and system for actuating semi-commanded valve for multi-suction alternative compressor

Abstract

A method for actuating a semi-controlled valve that acts in synchronism with the compression cycles of an alternative compressor, and a system for actuating a multi-suction alternative compressor semi-controlled valve. The method for actuating the semi-controlled valve involves detecting at least one compression peak in the course of at least one mechanical cycle of the alternative compressor and switching the functional status of at least an alternative compressor semi-controlled valve based on the detection.

Claims

1. A system for actuating a multi-suction alternative compressor semi-commanded valve, comprising: at least one semi-commanded valve configured to be electrically actuated by at least one magnetic field generator; at least one data processing core; and at least one sensor, wherein: the at least one data processing core is configured to receive electric stimuli from the at least one sensor and configured to generate electrical stimuli for the at least one magnetic field generator; the multi-suction alternative compressor comprises a compression cylinder fluidly connected to at least two suction orifices and at least one discharge orifice; each suction orifice of the at least two suction orifices is cooperative with one or more suction valves; and at least one of the one or more suction valves comprises the at least one semi-commanded valve; the at least one sensor is configured to measure at least one parameter of the multi-suction alternative compressor; the at least one data processing core is configured to determine a compression peak of the multi-suction alternative compressor by measuring a peak of the at least one parameter measured by the at least one sensor, and is configured to energize the at least one magnetic field generator based on the determined compression peak; the at least one sensor comprises an amperemeter; and the determination of the compression peak is based on the occurrence of the peak of the at least one parameter which is out-of-phase relative to the compression peak, wherein the peak of the at least one parameter is defined by a positive peak of an electric current of an electric motor of the multi-suction alternative compressor measured by the amperemeter.

2. The system according to claim 1, wherein the at least one semi-commanded valve comprises a reed-type metal valve.

3. The system according to claim 1, wherein the at least one magnetic field generator comprises at least one inductor.

4. The system according to claim 1, wherein the at least one magnetic field generator comprises a coil.

5. The system according to claim 1, wherein the at least one data processing core comprises a microcontroller.

6. The system according to claim 1, wherein the at least one data processing core comprises a microprocessor.

7. A system for actuating a multi-suction alternative compressor semi-commanded valve, comprising: at least one semi-commanded valve configured to be electrically actuated by at least one magnetic field generator; at least one data processing core; and at least one sensor, wherein: the at least one data processing core is configured to receive electric stimuli from the at least one sensor and configured to generate electrical stimuli for the at least one magnetic field generator; the multi-suction alternative compressor comprises a compression cylinder fluidly connected to at least two suction orifices and at least one discharge orifice; each suction orifice of the at least two suction orifices is cooperative with one or more suction valves; and at least one of the one or more suction valves comprises the at least one semi-commanded valve; the at least one sensor is configured to measure at least one parameter of the multi-suction alternative compressor; the at least one data processing core is configured to determine a compression peak of the multi-suction alternative compressor by measuring a peak of the at least one parameter measured by the at least one sensor, and is configured to energize the at least one magnetic field generator based on the determined compression peak; the at least one sensor comprises a tachometer; and the determination of the compression peak is based on the occurrence of the peak of the at least one parameter which is out-of-phase relative to the compression peak, wherein the peak of the at least one parameter is defined by a negative peak of a rotating shaft speed of an electric motor of the multi-suction alternative compressor measured by the tachometer.

8. The system according to claim 7, wherein the at least one semi-commanded valve comprises a reed-type metal valve.

9. The system according to claim 7, wherein the at least one magnetic field generator comprises at least one inductor.

10. The system according to claim 7, wherein the at least one magnetic field generator comprises a coil.

11. The system according to claim 7, wherein the at least one data processing core comprises a microcontroller.

12. The system according to claim 7, wherein the at least one data processing core comprises a microprocessor.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The present invention is described in detail based on figures listed below, wherein:

(2) FIGS. 1A and 1B illustrate schematic graphs related to the detection of compression peak through electric current analysis of the compressor motor;

(3) FIGS. 2A and 2B illustrate schematic graphs related to the detection of compression peak through analysis of the rotating shaft speed of the compressor motor;

(4) FIG. 3 illustrates a schematic graphic related to the detection of compression peak through analysis of the compression cylinder pressure;

(5) FIGS. 4A and 4B illustrate exemplary graphs related to actuation synchronism of a semi-commanded valve in accordance with the method of the present invention;

(6) FIG. 5 illustrates an exemplary graph related to the energizing time responsible for actuation of a semi-commanded valve in accordance with the presently claimed method.

(7) FIG. 6 illustrates a block diagram referring the preferred embodiment of application of the controlled valve actuation system in accordance with the present invention; and

(8) FIG. 7 conceptually illustrates the preferred embodiment of the controlled valve actuation system.

DETAILED DESCRIPTION OF THE INVENTION

(9) Before beginning the detailed description of the invention, it is necessary to define some of the following terms and expressions used.

(10) The expression semi-controlled valve refers to any type of valve, either suction or discharge valve, which needs to be essentially associated with an actuation system or apparatus, that is, a non-automatic actuation valve. With regard to the present invention and in accordance with its preferred embodiment, pallet-type valves made of metal blade are disclosed. Moreover, and still in accordance with the preferred embodiments of the present invention, said valves are actuated by a magnetic field generator, that is, a coil.

(11) The expression mechanical cycle of the compressor refers to a compression cycle, concerning a back-and-forth movement of the alternative piston, which is displaced inside the compression cylinder. A compressor mechanical cycle is generally equivalent to a mechanical cycle or return of the electric motor contained in the compressor.

(12) The expression compression peak refers to a maximum pressure that a working fluid (usually refrigeration fluid) is subjected within the compression cylinder. Generally speaking, the compression peak is reached some time before the opening of the discharge valve near the maximum positive displacement of the piston inside the compression cylinder. It should be pointed out that only one compression cycle per mechanical cycle occurs.

(13) The expression functional status switching means a valve alteration position, that is, from the closed position to the opened position or from the opened position to the closed position.

(14) Regarding the Controlled Valve Actuation Method Based on Compression Peak

(15) In accordance with the present invention, the preferred controlled valve actuation method based on compression peak comprises two sequential steps.

(16) The first step comprises detecting the compression peak in the course of the alternative compressor mechanical cycles.

(17) The second step comprises switching the functional status of an alternative compressor valve based on the detection of at least a compression peak in the course of at least one alternative compressor mechanical cycle carried out in the first step.

(18) More particularly, and in accordance with the present invention, detection of the compression peak in the course of the alternative compressor mechanical cycles is effected by measuring the peak of one of the parameters intrinsic in the functioning of said alternative compressor.

(19) Regarding the Step of Detecting Compression Peaks

(20) FIGS. 1A, 1B, 2A, 2B and 3 illustrate possibilities of detecting the compression cycle in accordance with the present invention.

(21) FIGS. 1A and 1B illustrate detection of the compression peak 1 (compression cylinder pressure PC) in a single mechanical cycle 2, by measuring the superior peak 21 (positive peak) of the electric current CE of the electric motor of the alternative compressor 5.

(22) It should be pointed out the from the operation view point checked in real tests, compression peak does not occur at the superior neutral point but rather immediately before since the discharge valve opens prior to the superior neutral point, thereby equalizing the cylinder pressure to the condensation pressure.

(23) From FIG. 1A it can be inferred that the compression peak 1 corresponds to the superior peak 21 of electric current CE and the compression peak 1 is valid because electric motor makes more effort (and consumes more electric current) when alternative piston reaches at high pressure its maximum positive displacement within the compression cylinder before the opening of the automatic flexible discharge valve, thus generating the highest compression pressure.

(24) From FIG. 1B it can be inferred that the compression peak 1 may also correspond to an out-of-phase parameter 21 observed in relation to the superior peak 21 of electric current CE of the electric motor of the alternative compressor 5. This relationship, using an out-of-phase parameter 21, can be required (in practical applications) so as to more accurately determine a position at which compression peak occurs. Such an out-of-phase parameter may compensate, for example, for the delay effect on the variation of the electric current CE of the electric motor of the alternative compressor 5 when subjected to a compression force PC due to essentially inertial factors of electromechanical assemblies of said electric motor of the alternative compressor 5. Out-of-phase parameter 21 refers to a parameter preferably experimentally set.

(25) Consequently, it is noted that each mechanical cycle 2 of said alternative compressor comprises only one compression peak 1, which occurs during the compression period 11 (complementary to the suction period 12).

(26) It should be mentioned that measurement of the variation of electric current CE of the electric motor of said alternative compressor 5 can be conducted by methods and devices already known by a person skilled in the art.

(27) FIGS. 2A and 2B illustrate detection of compression peak 1 (of pressure PC of the compression cylinder), in a single mechanical cycle 2), by measuring lower peak 22 (negative peak) of speed VM of the electric motor of the alternative compressor 5.

(28) From FIG. 2A it can be seen that compression peak 1 corresponds lower peak 22 of speed VM of the electric motor of the alternative compressor 5. Such relationship between lower peak 22 of speed VM and compression peak 1 is valid because the electric motor makes more effort (and presents a lower instantaneous speed) when the alternative piston reaches, at high pressure, its maximum positive displacement within the compression cylinder before the opening of the automatic flexible discharge valve and thus generating higher compression pressure.

(29) From FIG. 2B it can be noted that compression peak 1 can also correspond to an out-of-phase parameter 22 observed in relation to lower peak 22 of speed VM of the electric motor of the alternative compressor 5. Such relationship, using an out-of-phase parameter 22, can be necessary (in practical applications) to determine with higher accuracy the position at which the compression peak occurs. This out-of-phase parameter may compensate, for example, for the delay effect on the variation of speed VM of the electric motor of the alternative compressor 5 when subjected to compression force PC due to essential inertial factors of electromechanical assemblies of said electric motor of the alternative compressor 5. The out-of-phase parameter 22 is a preferably experimentally set parameter.

(30) Consequently, it is verified that each mechanical cycle 2 of said alternative compressor comprises at least a compression peak 1, which occurs during compression period 11 (complementary to the suction period 12).

(31) It should be stressed out that measurement of the variation of speed VM of alternative compressor electric motor can be performed by methods and devices known by a person skilled in the art.

(32) FIG. 3 illustrates the detection of the compression peak 1 (of the compression cylinder pressure PC) in a single mechanical cycle 2 by directly measuring said compression cylinder pressure PC. From this figure, it can also be seen that the compression peak 1 corresponds to peak 23 of the compression cylinder pressure PC, Calculation of the variation of the compression cylinder pressure PC can be performed by methods and devices already known by a person skilled in the art.

(33) Although this way of detecting said compression peak illustrated in FIG. 3 seems to be simpler than the ways of detecting compression peak illustrated in FIGS. 1A, 1D, 2A and 2B, it can be noted that installation of a pressure sensor (pressostat or the like) inside the compressor cylinder in order to measure the pressure PC refers to an invasive form of obtaining data and, consequently, it is not the most suitable form.

(34) In parallel, the ways of detecting peak illustrated in FIGS. 1A, 1B, 2A and 2, because they comprise calculations of electric parameters, are non-invasive forms since different electric parameters of the motor are easily assessed.

(35) Nevertheless, the step of detecting the compression peak can also be effected by not illustrated forms.

(36) Regarding the Step of Switching the Functional Status of a Valve

(37) As explained above, the method for actuating a controlled valve based on compression peak initially comprises compression peaks occurring through different types of obtaining data.

(38) In this sense, the main merit of the present invention is to use detection of compression peaks to deliberately promote the switching of the operation status of one or more controlled valves (valves equivalent to those valves disclosed in BR PI1105379-8) in synchronism with the compression cycles of the alternative compressor 5.

(39) As illustrated in FIGS. 4A and 4B, the valve operation status (particular a suction valve) can be switched on the basis of the detection of at least one compression peak in the course of at least one alternative compression mechanical cycle.

(40) Said figures show that said valve (not illustrated) assumes only one among two possible operational statuses EV: The operational status opened 31 and the operational status closed 32.

(41) Therefore, and in accordance with the present invention, the switching of the operational statuses 31 and 32 takes place by using already known means (e.g. using an electromagnetic field generator as described in the document BR PI1105379-8) on the basis of detection of at least one compression peak in the course of at least one mechanical cycle 2 of the alternative compressor 5.

(42) FIG. 4A illustrates a first possibility, as to say, of switching the valve operational statuses.

(43) As can be noted, a first change in the operational status (from closed 32 to opened 31) is triggered by a detected compression peak 1. A second change in the operational status (from opened 31 to closed 32) is triggered by another compression peak 31 detected in mechanical cycles later.

(44) In this case, switching of the operational statuses 31 and 32 does not occur in function of successive compression peaks 1 but rather in function of relevant compression peak 1 in accordance with predefined functional logics. Specifically in this case, a first switching between three compression peaks is performed and then a second switching is performed between three compression peaks. Consequently, the valve remains opened for a longer time, and such logics can be interesting for any system (e.g. a refrigeration system with its own specifications).

(45) Therefore, and since the operational statuses 31 and 32 can be continuously kept in the course of multiple mechanical cycles 2, it is then possible to controlby means of the switching time of the operational statuses 31 and 32 of a (suction) valvethe capacity of an alternative compressor. In this example, the valve actuation element (not illustrated) is continuously kept energized/de-energized in the course of multiple mechanical cycles of the compressor.

(46) From FIG. 4B it can be verified that switching between operational statuses 31 and 32 may occur in function of successive compression peaks 1, that is, valve operational status is switched at each detection of compression peak.

(47) As the compression peaks 1 occurs in synchronous form, it can then be verified that, in this case, the switching between operational statuses 31 and 32 are also synchronous. To this effect, the valve actuation element (not illustrated) is energized/de-energized) in a pulse form at each mechanical cycle of the compressor motor.

(48) The switching between operational statuses 31 and 32 of the semi-controlled valve preferably occurs by selective energization of a magnetic field generator (coil). In this situation and considering that said semi-controlled valve 3 comprises a metal pallet-type suction valve, it is important to mention that selective energization of its respective magnetic field generator may not occur during all the period of said switching.

(49) This stems from the fact that the valve tends to remain in a desirable operational status after a first selective energization of its respective magnetic field generator by the own compression inertia.

(50) An exemplary graph is illustrated in FIG. 5, wherein the curve of pressure PC in the interior of the compression chamber of the compression is illustrated.

(51) This figure shows a value PX related to the pressure to automatically maintain a desirable operational status (after a first selective energization of its respective magnetic field generator).

(52) With regard to the pressure PC within the compression chamber same is higher than the value PX (which is usually related to the pressure in the suction line of the compressor), and considering the position of the compression peak 1, it is possible to define a region K1+K2 where the semi-controlled valve 3 tends to maintain (in function of the pressure differential) its desirable operational status.

(53) Consequently, it is necessary to energize the respective magnetic field generator of the semi-controlled valve 3, with electric current CV, only in former and posterior regions to the region K1+kK. With this kind of actuation, power is saved during multiple switchings between the operational statuses 31 and 32 of the semi-controlled valve 3,

(54) The value of advance K1 and delay K2 are preferably experimentally obtained.

(55) Regarding the System for Actuation of Semi-Controlled Valve for Multi-Suction Alternative Compressor

(56) FIGS. 6 and 7 schematically illustrate the implementation of the above-described method by a dedicated system in a multi-suction compressor and, more particularly, a multi-suction compressor as described in the first concept of PCT/BR2011/000120.

(57) To this effect, FIG. 6 illustrates a refrigeration system suitable for implementation of this kind of double-suction compressor.

(58) It is therefore illustrated an exemplary refrigeration system that operates suctioning refrigerant from two operation lines at different temperatures and pressures, which is constituted by a condensation unit 9 connected to discharge outlet 91 of the double-suction compressor 5 by two evaporator units wherein each one comprises an expansion element and 15 an evaporator 7, both connected to said double-suction compressor 5 by a low pressure suction line 72 and a high pressure suction line 71. The double-suction compressor 5 comprises at least one sensor 74 coupled to an electronic unit 6.

(59) Furthermore, the system also comprises an electronic unit 6 for actuating the electric motor of the double-suction compressor 5 and at least a semi-controlled valve 3 disposed in the compressor. The electronic unit 6 comprises a data processing core 73 capable of receiving electric stimuli from the at least one sensor 74. In this example, the semi-controlled valve comprises one of the suction 20 valves. Said semi-controlled valve 3 comprises one semi-controlled valve because it can be closed by injecting current into coil 61 and it can be exclusively opened via pressure difference between its suction line 71 and compression cylinder.

(60) Furthermore, and as illustrated in FIG. 7 (which shows the interior of the compression cylinder), it is further provided another conventional non-controlled pallet-type suction valve and a conventional, also not controlled, pallet-type discharge valve.

(61) Disclosed examples of the preferred embodiment of the present invention shall lead to the interpretation that the scope thereof contemplates other possible variations, which are only limited by the contents of claims, included therein the possible equivalent means.