FR2529313A1 - MOTOR DRIVEN COMPRESSION TYPE REFRIGERATOR CIRCUIT - Google Patents

Abstract

TO DECREASE THE LARGE STATIC TORQUE WHICH IS THE ORIGIN OF THE EXCESSIVE SIZING OF THE ELECTRIC MOTOR FOR DRIVING A COMPRESSOR OF A REFRIGERATOR CIRCUIT, A REFRIGERANT ACCUMULATOR 5 IS PROVIDED TO ACCUMULATE THIS FLUID DURING PERIODS. FROM THE COMPRESSOR AND TO REJECT IT ON STARTING THE COMPRESSOR. APPLICATIONS: REFRIGERATORS.

Description

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  _ 1 _ "Refrigeration circuit of the compression type with motor drive" The invention relates to a refrigerator circuit of the type with

  motor driven compression with at least one evaporator

erator and at least one condenser.

  In these circuits, the electric motor is larger than is necessary for normal operation in order to obtain a large static or starting torque making it possible to overcome the

  considerable initial resistance mainly due to the density

  refrigerant contained in the compressor.

  For this purpose, it is necessary that the motor is provided with a starting capacitor or that it is of the type with short-circuit winding, that is to say that in addition to the winding of operating speed, it has a starting winding, case which

occurs most frequently.

  However, the invention aims to reduce the resistance to

  rage and to allow a simpler and in particular circuit structure

  the use of lower cost electric motors.

  To this end, in accordance with the invention, a cooling circuit

  manager of the type described in the preamble is remarkable in that

  an accumulator is linked to the refrigerator circuit downstream of the

  evaporator to extract refrigerant from the circuit during

  compressor shutdown periods and return it upon start-

  rage of the compressor In the circuit thus designed, the density of the refrigerant contained in the compressor is lower, which reduces the starting torque of the electric motor In addition, the

  compressor may have smaller dimensions than without using

tion of the accumulator.

  The following description, with reference to the appended drawing, shows

  will better understand how the invention is made.

  The single figure schematically represents two embodiments of the refrigerator circuit, the first of these embodiments being represented by solid lines while the part of the other embodiment which differs from the first -2-

  is represented by dashed lines.

  In the figure, reference 1 indicates a compressor

  reciprocating motion which, together with its electric drive motor, is housed in a sealed case Under the action of the compressor, the refrigerant which circulates in the

  refrigerator circuit (a refrigerator appliance or a heat pump

  their for example) and which in general is a halogenated hydrocarbon

  (marketed under the name of "freon", is brought in a condensa-

  tor 2 to then be directed to the evaporator 4 passing through a capillary tube 3 The fluid returns from the evaporator

  to compressor 1 which is controlled in a known manner by a thermos-

  state measuring the temperature of the environment or compartment

  conditioned by the evaporator or the condenser.

  In order to decrease the density of the refrigerant to be displaced

  cer from the start of the compressor and decrease accordingly the resistances which oppose it as well as the torque

  static motor, an accumulator has been provided in the circuit

  refrigerator downstream of the evaporator By absorbing a certain quantity of the refrigerant, this accumulator decreases the volume to be moved by the compressor during its start-up and, after the start-up step, it returns to the circuit at least part of the

  fluid absorbed to reabsorb it during the period in the

  the compressor is at rest In practice, such a result

  tat can be obtained in different ways, two of which are represented

  felt on the drawing and described in the rest of this presentation.

  The accumulator is represented by a container 5 arranged at

  the end of a pipe 6 which branches onto the re-circuit

  refrigerator, downstream of the evaporator 4, i.e. between the evaporator

  rator 4 and the compressor 1 The container 5 contains a given quantity of material 7, capable of absorbing a certain quantity of coolant contained in the circuit The absorbency of this absorbent material is linked to the temperature, in the sense that this power absorbent decreases as the temperature increases A suitable absorbent material is silica gel for example The container 5 is in thermal transmission contact with the housing of the motor-driven compressor 1, in the sense that c is the temperature of the latter which modifies the power

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  -3- absorbent material 7 and therefore the amount of fluid

refrigerant extracted from the circuit.

  It is assumed that the compressor is at rest and that its time

  temperature is low The temperature of the material 7 is also low, so that it has a high absorptivity for the refrigerant of the circuit A significant quantity of said fluid is

  thus absorbed by the material 7 When the compressor starts

  sor, this quantity is not contained in the circuit and the density

  coolant t is lower The starting torque required by the electric motor is therefore lower than it would be

  in the absence of the accumulator Therefore, the construction of the mo-

  electric tor may be simpler and its costs may be lower, the motor not needing to be provided with a starting circuit (or winding) In the case of larger loads, this circuit (or winding) start-up can be planned in the

  engine but, anyway, it will be smaller (and therefore less cost-

  teux) than the one commonly used.

  The compressor gradually reaches its operating temperature and during this step, the absorbent material 7, heated in this way by the case, rejects the absorbed fluid, so that it enters the circuit, which continues until the establishment of the normal operating condition,

  in which the material 7 ceases to reject the fluid.

  When the compressor stops, its temperature and, by

  Consequently, the temperature of the material 7 decreases, which increases

  the absorbency of it, so that it will extract fluid

  refrigerant in the circuit Thus, during the next start of the

  presser, the refrigerant contained in the circuit has again

the lower density.

  Then the described operating cycle is repeated.

  In a modified embodiment, which is shown

  by broken lines in the same figure, the reci-

  pient 5 is replaced by a 5 A container communicating with the branch

  che 6 The container 5 A is physically separated from the compressor 1, so that it is practically not influenced by the temperature of the latter In the container 5 A, which also contains the material

  absorbent, there is an electric heating element 8 This element

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  heating is associated with a timer circuit (not shown

  which connects it to the power supply when the compressor starts and disconnects it after a certain time, that is to say after a time which is supposed to be sufficient so that, the heating element being disconnected, the absorbent material, heated to temperature, could have established in container 5 a temperature which

  is close to the temperature reached in the material 7 In

  very cool, the refrigerant itself acts as a means

heating material 7.

  Another alternative is to heat the material in use.

  reading at least part of the heat emitted by the condenser.

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Claims (5)

  1 Refrigeration circuit of the compression type with drive   by motor comprising at least one evaporator and at least one condenser   sor, characterized in that an accumulator is linked to the cooling circuit   operator downstream of the evaporator to extract refrigerant   rant of the circuit during periods of compressor shutdown and   send it back when the compressor starts.   2 circuit according to claim 1, characterized in that the accumulator comprises at least one container communicating with the circuit and containing a material having for the coolant an absorbency which decreases as the increase of temperature.   3 Circuit according to claim 2, characterized in that   said material consists of silica gel.   Circuit according to claim 2, comprising means   for heating said material.   Circuit according to Claim 4, characterized in that the heating means consist of a heating element   electric designed to be engaged together with the compressor   and to be triggered after a predetermined time.   6 Circuit according to claim 4, characterized in that the heating means are constituted by the refrigerant itself. 7 Circuit according to claim 4, characterized in that   the heating means consist of the compressor housing motor-driven valve.   8 Circuit according to claim 4, characterized in that the heating means are constituted by at least part of the condenser.