GB2222231A

GB2222231A - Blocking valve for refrigeration of air-conditioning systems

Info

Publication number: GB2222231A
Application number: GB8915259A
Authority: GB
Inventors: Egidio Berwanger; Marcos Guilherme Schwarz
Original assignee: Empresa Brasileira de Compressores SA
Current assignee: Empresa Brasileira de Compressores SA
Priority date: 1988-08-12
Filing date: 1989-07-03
Publication date: 1990-02-28
Anticipated expiration: 2009-07-03
Also published as: IT1231150B; CA1313768C; CN1043195A; GB8915259D0; IT8921220A0; FR2635367A1; ES2015204A6; DK166742B1; JP2818445B2; CN1039848C; DE3926492A1; DK396389D0; DK396389A; SE467637B; GB2222231B; SE8902424L; BR8804215A; JPH02168088A; DE3926492C2; FR2635367B1

Description

C 22 2 2- 22- 3 1 BLOCKING VALVE FOR REFRIGERATION OR AIR-CONDITIONING

SYSTEMS This invention refers to refrigeration or air conditioning systems which use capillary tubes as control element and, more specifically, to a blocking valve for these systems. Refrigeration and air conditioning systems essentially consist of one compressor, one condenser, a capillary tube and one evaporator. When in these systems, the evaporator temDerature reaches a pre-determinated value and the compressor is switched off, there occLrs the migration of the heated fluid from the condenser side (the high pressure side) to the evaporator (low pressure side). This migration of the refriqerant to the evaporator at each stop of the compressor causes a loss of the cooling capacity in the system (anproximately 6% in systems which use reciprocating compressors and 12% in systems' which use rotary compressors), since the refrigerant,besides heating the evaporator, must be compressed once again at each new start of the compressor, when the normal oDeration cycle of the system is restablished, that is, when the pressure and temperature levels are restablished in each unit of the system. A first known solution to solve this problem involves the use of a solenoid valve, installed between the condensator and the capillary tube. In this cooling cycle, the valve is energized simultaneously with the stop of the compressor (rotary compressor), preventing the refrigerant from flowing from the condenser to the evaporator. One problem of this solution is that the valve remains energized during the stop of the refrigeration system, and consequently, during the stoD of the compressor, cQnsuminq during that time a considerable amount of energy. Another known solution is described in the patent document GB 2121942 A. This system includes a one-way valve (26) installed between the suction side (21a) of a comoressor (21) and the evaporator (25) to prevent the refrigerant flow from the side of the suction to the evaporator. A pressure 1 2.

responsive type valve (37) is installed between the condenser and the evaPorator (25) to nrevent the flow of the fluid from the condenser (22) to the evaporator (25) during the stop of the compressor (21). A connection tube (34) is connected between the valve 37 and the suction side (21a) of the compressor (21) to transmit the Pressure from the suction side to the valve. The closure of the valve (37) is controlled by the suction Pressure from the compressor (21). When the comx)ressor (21) suction pressure becomes higher than a given predetermined value, it acts on the valve (37) Dreventi-nq the passage of the refrigerant fluid from the condenser to the evaporator. This solution has the inconvenience that it can only be applied to refriceration systems which use rotary comDressors. since this valve (37) is controlled by the pressure of the refrigerant gas which returns through the suction line durina comT. )ressor (21) stoz)s. This return of the refrigerant gas through the suction line after the compressor stops, occurs due to the constructive characteristics of the rotary compressors. In this type of compressor, the refrigerant gas, discharged at a high pressure into the housing, leaks through the mechanical assembly to the suction side, which effect is used to activate the valve (37). In reciprocating compressors, this effect of the refrigerant gas leakage through the mechanical assembly to the suction line does not occur, thus making impossible the use of this tyoe of valve in systems using reciDrocating comPressors. Another inconvenience of this solution is the number of welds to be Derformed in the tubina due to the reauirement of at leat one additional tube (34) in the refriqeration circuit. Thii tube (34) is required for measuring the- oressure of the suction-line (21a). The objective of this invention is to DroDose a blocking valve for refrigeration and air conditioning systems which may be applied both in systems which use rotary compressors and in systems using reciprocating compressors.

A further objective of this invention is to [,roz)ose a bl.ockinq valve for refriqeration and air conditionina systems which have a low power consumntion.

Still another objective of this invention is to present a blocking valve for refrigeration air conditioninq systems, which does not require the installation of additional tubes in the mentioned systems, thus reducing the number of weldinq operations to a minimum.

The above objectives are reached with a blockinq valve to be installed in refrigeration or air conditioninq systems, of a type consisting essentially of:a hermetic compressor driven by an electric motor; one condenser and one evaporator, connected, respectively, at the compressor discharge and suction sides; a cax)illary tube tyne control element installed between the condenser and the evaporator: and a blockinq valve between the condenser and the capillary tube.

According to this invention the blocking valve comprises a housing defining an internal chamber with an inlet onening in fluid communication with the condenser and outlet oueninq in fluid communication with the evaporator; one sealinq maqnetic slide assembled inside the chamber, in a way that it can be displaced between a non operative x)osition, maintaining open the inlet and outlet openings, and an operative Dosition, sealing the outlet opening; electromagnetic elements assembled in the housing and selectively and automatically enerqized, preferably by the electric motor circuit, for a period -- sufficient to cause the displacement of the magnetic slide from one operational T)Osition to another accordinq to the energization of the compressor electric motor; the retention of the magnetic slide in its inoperative and oDerative positions being Performed by the action of non electromagnetic forces acting on the magnetic slide at least during the maintenance of same In the respective inoperative or onerative position.

In a Preferred form of the invention, the housing in which the magnetic slide is lodged consists of two tubular Parts assembled concentrically. The internal tubular Dart consists of a non magnetic material and is externally provided with 4.

opening and closing coils. The external tubular part consists of a ferromagnetic material and is externally assembled to the opening and closing coils, being fastened to the mentioned inner tubular part of the housing. In this preferred form of invention, the opening coil is connected in series with the electric motor start windinq. Consequently, the valve opening occurs simultaneously with the start of the motor, in which moment the oDening coil is energized and the magnetic slide displaced to the ooeninc! position. The retention of the slide in this position occurs by the action of its own weight. The valve must, therefore, be installed in a vertical position. The closin(l coil is connected in parallel with the motor terminals (main winding) at the same time the motor is switched off. The closing of the valve consequently occurs simultaneously with the disconnection of the motor, when it acts as generator during its deceleration, makinq an electric current to circulate through the closing coil, which displaces the magnetic slide to the closing position. The retention of the slide in this position is given by the difference of pressure between the high and low pressure sides of the system. The so constructed blocking valve presents a very reduced power consumption as, contrary to the conventional solution (solenoid valve), it does not remain energized durinq the standstill Period of the system, but is only energized in the instants the compressor stops and starts, which reDresents a fraction of a second. Besides, in the above described configuration, the current consumption of the Power supply system occurs only in the moment of the valve opening, whilst its closing is made at the expense of the power generated by the motor at the moment it is switched off and, therefore, without any consumption of current from the power supply. Another advantage of the blocking valve is that it does not require the installation of additional tubinqs in the system, thus making unnecessary additional welding operations, which i '. 1 5.

bring about more costs with tests and control. Another advantage which ought to be mentioned is that this valve is electrically driven, thus actinq indeuendently of the Pressures of the system. This is why it can be apolied in systems which use both rotary and alternative compressors. The invention will be hereafter described with reference to the enclosed drawings, where: Figure 1 is a schematic representation of a refrigeration system which uses a blocking valve in accor(lance with the invention; Figure 2 represents a longitudinal sectional view of the blocking valve of this invention; Figure 3 illustrates a sectional view taken according to line III-III of figure 2; Figures 4 and 5 represent two electric circuits of the valve, together with the compressor start devices; and Figure 6 illustrates a structural variation of the circuit shown in figure 5. As shown in figure 1, the refrigeration system consists essentially of one hermetic compressor 30, one condenser 31, one capillary tube 32 and one evaporator 33. in systems using rotary compressors a one-way valve 34 (check valve) is usually installed between the compressor 30 and the evaporator 33. The function of this valve is to Prevent the Passage of the heated refrigerant gas from the housing of the compressor 30 to the evaporator 33 in moments of-stoopage, of the system. In order to avoid the Passage of the refrigerant gas from the condenser 31 to the evaporator 33 through the capillary tube 32, during the compressor stoppage Periods, the system presents a blocking valve 40 installed, in example shown in the illustration, between the condenser 31 and the capillary tube 32. As shown in figures 2 and 3, the blocking valve 40 consists essentially of a magnetic slide 41 which is moving inside the housing 42. The housing 42 is formed by an inner round tubular part.42a and an outside round tubular part 42b, concentrically assembled.. As shown in the illustration, the inner tubular c 6 part 42a is externally Provided with coils of openinq 46 and closing 47. The outside tubular Dart 42b is externally assembled to the coils of opening 46 and of closinq 47, radially fastened to the inner tubular part 42a by mcans of an intermediate ring 48 and a pair of end disks 49a and 49b, these latter defining, tther with the inner tubular Dart 42a, a chamber in the inside of which slide 41 shifts. One aspect to be mentioned regarding the construction of the housing 42 is that the inner tubular uart 42a must be of a non magnetic material, whilst the outside tubular part 42b, the ring 48 and the disks 49a and 49b must be of magnetic material in order that the magnetic flow acts on the slide 41 of valve 40 (see the flow lines represented in figure 2). The housing 42 is connected to the condenser 31 (the high pressure side of the system) by means of the holes 43 performed at the disk 49b and to the evaporator 33(low pressure side of the system) by means of the end 44 of the capillary tube 32. The magnetic slide 41 is provided with a sealing surface 45, which in its closing position is seated on end 44 of the capillary tube 32, closing the passage of the refrigerant to the evaporator 33. As shown in figure 3, the magnetic slide 41 has a preferably square cross section with chamfered edges, so that the nucleus 41 may shift freely between the two positions without compressing the refrigerant fluid inside the chamber. Other polygonal forms of the sectionmay be adoDted in the construction of the slide 41. The valve is operated by means of the circuits shown in figures 4, 5 and 6. According to what is shown in figure 4, the electric circuit for operation of the blocking valve 40, is made up, in its preferred form, essentially by a closing coil 47, an opening coil 46 and a two-way switch 50, connected to the electric circuit of the motor, which consists of an start winding 51, starting device 52, main winding 53 and power source 54. The electric circuit of the motor normally includes a starting capacitor 55 connected in series with the start winding 51. The two-way switch 50 is normally operated 7.

C by the system thermostat. The blockinq valve opening takes place at the moment the motor starts when the starting switch 52 oermits the temporary circulation of the current through the opening coil 46, which is connected in series with the start wiDding 51 of the motor. By the temporary energizing of the oDeninq coil 46, slide 41 is displaced to the position shown in figure 2, i.e., with its sealing end 45 separated from the refrigerant fluid outlet opening or end 44 of the capillary tube 32 which leads to the evaporator 33. When deenergizing the start windinq of the motor and, consequently, the or)eninq coil 46, the slide 41 remains in its non ooerative or valve or)eninq nosition due to the action of its own weight, as the valve is assembled so as to have its inside chamber arranged at- least anproximately in a vertical manner. It should be however understood that the slide 41 can be kept in its inonerative position by the very oressure balance at the inlet and outlet openings of the chamber, sur)ported by the urovision of any mechanical device able to exert a slight elastic force on the slide, so as to force it lightly and constantly into the inoperative position. The closure of the blocking valve 40 occurs at the moment the motor is switched off, when the two-way switch 50 shifts from position A to position B, connecting in parallel the closure coil 47 of the valve 40 with the main winding 53 of the motor, when the latter is still in deceleration movement. During this -deceleration period, the motor acts as a P)ower generAor, imposing the temporary circulation of a current through the closure coil 47 generated by the main winclinq 53 which causes the displacement of the slide 41 by magnetic attraction up to the closure vosition. One of the alternative forms of the electric circuit required to operate the blockinq valve 40, is shown in figure 5. In this circuit the closure coil 47 is connected in series with a temporizing device 56 of the PTC type. The opening of the blocking valve 40 occurs in the same way as the one formerly described with basis on the circuit of figure 4.

G A.- i 8.

The closure of the blocking valve 40 in this alternative circuit form takes Dlace after the disconnection of the motor, when the twoway switch 57 shifts from position A to position B, connecting the uower source 54 to the closure circuit. When connected to the power source 54, the c16sure coil 47 is energized displacing the slide 41 to the closure position. The temporizing device 56, which in this case consists in a PTC element, makes that the circulation of the current through the closure coil 47 is temporary, limitinq after a certain time the current intensisty to a rather lower value than the initial one. One variation of this temnorizinq device 56 is shown in figure 6. This circuit consists of a diode 60 connected in series with a caDacitor 61 and with a discharge resistor 62, the capacitor 61 and the discharge resistor being connected in narallel. With the deenergizing of the closure coil 47, after the complete stop of the motor according to the configuration of figure 4 or after the period established by the temporizer 56 according to the configuration of figures 5 or 6, slide 41 remains in its operative position of valve closure by action of the pressure differential itself existing between the high and low nressure sides of the system. The opening of fluid outlet 44 from the valve chamber is dimensioned so as to warranty the application of a closing force on the slide 41 which surpasses the sum of all forces actinq on the slide in the sense to separate it from the closure nosition in the condition of the deenergized opening coil 46. It should further be understood that the oneninq and closure electromagnetic forces which act on the slide are dimensioned to warranty the safe displacing of the slide to its resnective operating positions and further that the activation period of _these forces are dimensioned to permit that the conditions of pressure in the system are reached, which are z)articular to each of the two operating conditions of same, represented by "compressor or)erating" and "compressor at standstill".

1 1 1

Claims

1 - "BLOCKING VALVE FOR REFRIGERATION OR AIR CONDITIONING SYSTEMS", of the type which includes: one hermetic comoressor driven by an electric motor; one condenser and one evaporator, respectively connected to the compressor discharge and suction sides; one capillary tube type control element placed between the condenser and the evaporator; and one blocking valve between the condenser and the control element, characterized in that the blocking valve comprises a housing (42) defininq an inside chamber with inlet opening (43) in fluid cowmnicathn with the condenser (31) and with the outlet oveninq (44) in fluid communication with the evaporator (33) by means of the control element (32); a sealing maqnetic slide (41) installed inside the chamber so that it can be displaced between a non operative or valve onening position and art operative or valve closure position, by means of sealing of the outlet opening (44); electromagnetic elements (46,47) assembled in the housing (42) and selectively and automatically energized during a time sufficient to cause the displacing of the magnetic slide (41) from one operating condition to another, according to the operating condition of the system, the retention of the magnetic slide (41) in its non operative and operative positions being accomplished by action of non electromagnetic forces acting on the magnetic slide (41), at least during the periods in which same remains in the respective operating position.

2 - "BLOCKING VALVE FOR REFRIGERATION OR AIR CONDITIONING SYSTEMS", according to claim 1, wherein the retention of the magnetic slide (41) in the non ooerative or valve openinq position ii oerformed by acti6n of its own weight.- 3 - "BLOCKING VALVE FOR REFRIGERATION OR AIR CONDITIONING SYSTEMS", according to claim 1, wherein the retention of the magnetic slide (41) in the operating or valve closure position is performed by means of pressure differential between the high and low pressure sides of the system.

2- (1 3 4 - "BLOCKING VALVE FOR REFRIGERATION OR AIR CONDITIONING SYSTEMS", according to claim 1, wherein tne housinq (42) comprises: an inside tubular part (42a) defining the mentioned chamber internally; an outside tubular part (42b) concentric and at a distance in relation to the inside tubular part (42a) a pair of end walls (49a, 49b) closing the two tubular parts (42a, 42b) and one intermediate ring (48), said end walls and said intermediate ring interconnecting radially the two tubular -parts (42a, 42b) and the electromagnetic elements (46, 47) being- assembled between the two tubular narts, in each of the two sides of the intermediate rinq.

- "BLOCKING VALVE FOR REFRIGERATION OR AIR CONDITIONING SYSTEMS", according to claim 4, wherein the inside tubular part (42a) is made of non magnetic material, whilst the outside tubular part (42b), the end walls (49a, 49b) and the intermediate ring (48) is made of ferromagnetic material.

6 - "BLOCKING, VALVE FOR REFRIGERATION OR AIR CONDITIONING SYSTEMS", according to whichever of claims 1 or 4, wherein the inlet (43) and outlet (44) openings of the fluid are installed in one of the_chamber end walls.

7 - "BLOCKING VALVE FOR REFRIGERATION OR AIR CONDITIONING SYSTEMS", according to claim 6, wherein the outlet opening (44) is defined by the projection of the caoillary tube (32) towards the inside of the valve chamber.

8 - "BLOCKING VALVE FOR REFRIGERATTON OR AIR CONDITIONING SYSTEMS", according to claim 4, wherein the maqnetic slide bears a sealing element (45) on its extreme contact surface with the outlet onening (44).

9 - "BLOCKING VALVE FOR REFRIGERATION OR AIR CONDITIONING SYSTEMS", according to claim 1, wherein the energization of the electromagnetic elements (46, 47) is made from the electric circuit of the compressor motor (30).

- "BLOCKING VALVE FOR REFRIGERATION OR AIR CONDITIONING SYSTEMS", according to claim 9, the mentioned electric motor including a main winding, one start winding and one startinq f C 3.

device, whereas the electromagnetic elemetits are defined by. one valve openina coil (46), connected in series with the auxiliary windinq (51) and with the startinq device (52) of the electric motor, so that it is enerqiz(?d simultaneously with the start of tile electric motor; and one valve closure coil (47) to be automatically enerqized simultancously with the deenergizing of the electric motor.

11 - "BLOCKING VALVE FOR REFRIGERATION OR AIR CONDITIONING SYSTEMS", according to claim 10, wherein the closure coil (47) is automatically connected in Parallel with the wain windinq (53) of the electric motor, at the moment of deenergizing of the latter, so as to be energized by the current qenerated by the electric motor during the deceleration of the rotor.

12 - "BLOCKING VALVE FOR REFRIGERATION OR AIR CONDITIONING SYSTEMS", according to claim 10, wherein the closure coil (47) is connected in series with a temporizing device (56), which deenergizes the closure coil (47) after a Period of time had Passed from the deenergizing of the electric motor.

13 - "BLOCKING VALVE FOR REFRIGERATION OR AIR CONDITIONING SYSTEMS", according to claim 12, wherein the temDorizing device 36) consists of a PTC tyne element.

14 - "BLOCKING VALVE FOR REFRIGERATION OR AIR CONDITIONING SYSTEMS", according to claim 12, wherein the temporizing device (56) is defined by an electronic circuit formed by a diode (60) connected in series with a canaciter (61) and with a discharge resistor (62), the capacitor (61) and thedischarge resistor (62) beinq connected in Parallel.

- "BLOCKING VALVE FOR REFRIGtRATION OR AIR CONDITIONING SYSTEMS", according to whichever of the claims from 10 to 14, wherein the energizing_of the closure coil (47) is controlled by a switch (50) provided in the compressor motor suoPly electric circuit and automatically activated in accordance with one oerating condition of the system.

16 - 'BLOCKING VALVE FOR REFRIGERATION OR AIR CONDITIONING SYSTEMS", according to claim 15, wherein the operating condition of tht system is a temperature condition of the system.

Pued 1990atThe Patent O=ce, State House. %7 t Helburn.londonWC1R4TP. Further coplearnaybe obwnedtrorn The Patent OMC.