SPECIFICATION
`
`TITLE OF THE INVENTION
`
`REFRIGERATION APPARATUS
`
`BACKGROUND OF THE INVENTION
`
`[0001]
`
`The present invention relates to a refrigeration
`
`apparatus including a refrigerant circuit in which a
`
`refrigerant discharged from a compressor is condensed and
`
`then evaporated to exert a cooling function.
`
`[0002] Heretofore, a refrigeration apparatus using a
`
`compressor has been constituted of a refrigerant circuit in
`
`which the compressor, a condenser, a capillary tube (a
`
`pressure reducing unit) and an evaporator are annularly
`
`connected to one another via pipes. A'predetermined'
`
`refrigerant is introduced in this refrigerant circuit.
`
`When the compressor is operated, a high—temperature gas
`
`10
`
`15
`
`refrigerant discharged from the compressor is condensed in
`
`the condenser, radiates heat and is liquefied. Afterward,
`
`the pressure of the refrigerant is reduced by the capillary
`
`20
`
`tube, and the refrigerant flows into the evaporator to
`
`evaporate, absorbs vaporization heat from a surrounding
`
`area to cool the evaporator, and returns to the compressor.
`
`[0003] Here, a suction side pipe of the compressor is
`
`connected, via the pressure reducing unit,
`
`to a tank
`
`25
`
`(hereinafter referred to as the expansion tank) which
`
`stores the refrigerant introduced in the refrigerant
`
`circuit dUring the stop of the compressor.
`
`In consequence,
`
`
`
`TITLE OF THE INVENTION
`
`REFRIGERATION APPARATUS
`
`BACKGROUND OF THE INVENTION
`
`[0001]
`
`The present invention relates to a refrigeration
`
`apparatus including a refrigerant circuit in which a
`
`refrigerant discharged from a compressor is condensed and
`
`then evaporated to exert a cooling function.
`
`[0002] Heretofore, a refrigeration apparatus using a
`
`compressor has been constituted of a refrigerant circuit in
`
`which the compressor, a condenser, a capillary tube (a
`
`pressure reducing unit) and an evaporator are annularly
`
`connected to one another via pipes. A'predetermined'
`
`refrigerant is introduced in this refrigerant circuit.
`
`When the compressor is operated, a high—temperature gas
`
`10
`
`15
`
`refrigerant discharged from the compressor is condensed in
`
`the condenser, radiates heat and is liquefied. Afterward,
`
`the pressure of the refrigerant is reduced by the capillary
`
`20
`
`tube, and the refrigerant flows into the evaporator to
`
`evaporate, absorbs vaporization heat from a surrounding
`
`area to cool the evaporator, and returns to the compressor.
`
`[0003] Here, a suction side pipe of the compressor is
`
`connected, via the pressure reducing unit,
`
`to a tank
`
`25
`
`(hereinafter referred to as the expansion tank) which
`
`stores the refrigerant introduced in the refrigerant
`
`circuit dUring the stop of the compressor.
`
`In consequence,
`
`
`
`an equilibrium pressure in the refrigerant circuit during
`
`the stop of the compressor is lowered to facilitate the
`
`operation of the compressor during the stop of the
`
`compressor (see Japanese Patent Application Laid-Open No.
`
`62—73046).
`
`[0004] However, since the expansion tank is provided with
`
`the pressure reducing unit as described above,
`
`the
`
`following problems occur.
`
`It is difficult to quickly
`
`10
`
`15
`
`collect the refrigerant of the refrigerant circuit in the
`
`expansion tank during the stop of the compressor, and much
`
`time is required for achieving the equilibrium pressure in
`
`the refrigerant circuit. Therefore,
`
`in a case where the
`
`compressor is restarted in a state in which the refrigerant
`
`circuit has a high pressure, a load to be applied to the
`
`compressor increases. Consequently,
`
`in a case where the
`
`compressor is not restarted until the equilibrium pressure
`
`is achieved,
`
`the operation ratio of the compressor lowers,
`
`and a very long time is required for performing a pull—down
`
`operation at a time when a power source of the
`
`20
`
`refrigeratiOn apparatus turns on.
`
`SUMMARY OF THE INVENTION
`
`[0005]
`
`The present invention has been developed to solve
`
`conventional technical problems, and an object thereof is
`
`25
`
`to provide a refrigeration apparatus capable of quickly
`
`collecting,
`
`in an expansion tank, a refrigerant in a
`
`refrigerant circuit during the stop of a compressor and
`
`
`
`capable of decreasing a load to be applied to the
`
`compressor during.restart.
`
`[0006]
`
`A refrigeration apparatus of the present invention
`
`is characterized by comprising: a refrigerant circuit in
`
`5
`
`which a refrigerant discharged from a compressor is
`
`condensed and then evaporated to exert a cooling function;
`
`and‘a tank connected to a pipe of the compressor on a
`
`suction side via a pressure reducing unit,
`
`the pressure
`
`reducing unit being connected in_parallel with a check
`
`10
`
`valve,
`
`the direction of the tank being the forward
`
`direction of the check valve.
`
`[0007]
`
`A refrigeration apparatus of the invention of a
`
`second aspect is characterized by comprising: a high—
`
`temperature-side refrigerant circuit and a low-temperature-
`
`15
`
`side refrigerant circuit each constituting an independent
`
`refrigerant closed circuit in which a refrigerant
`
`discharged from a compressor is condensed and then
`
`evaporated to exert a cooling function, an evaporator of
`
`the high—temperature-side refrigerant circuit and a
`condenser of the low—temperatureeside refrigerant circuit
`
`2O
`
`constituting a cascade heat exchanger, an evaporator of the
`
`low—temperature-side refrigerant circuit achieving an
`
`extremely low temperature; and a tank connected to a pipe
`
`of the compressor of the low—temperature-side refrigerant
`
`25
`
`circuit on a suction side via a pressure reducing unit,
`
`the
`
`pressure reducing unit being connected in parallel with a
`
`check valve.
`
`the direction of the tank being the forward
`
`
`
`direction of the check valve.
`
`[0008]
`
`A refrigeration apparatus of the invention of a
`
`third aspect is characterized by comprising: a compressor,
`
`a condenser, an evaporator, and a plurality of intermediate
`
`heat exchangers and a plurality of pressure reducing units
`
`connected in series so that a refrigerant fed back from the
`
`evaporator circulates, wherein a plurality of types of non—
`
`azeotropic mixed refrigerants are introduced, a condensed
`
`refrigerant in the refrigerants fed through the condenser
`
`is allowed to join the intermediate heat exchanger via the
`
`pressure reducing unit, and a non—condensed refrigerant in
`
`the refrigerants is cooled by the intermediate heat
`
`exchanger to successively condense the refrigerant having a
`
`lower boiling point, and the refrigerant having the lowest
`
`boiling point is allowed to flow into the evaporator via
`the final—stage pressure reducing unit to obtain an
`
`extremely low temperature,
`
`the refrigeration apparatus
`
`further comprising: a tank connected to a pipe of the
`
`compressor on a suction side via the pressure reducing unit,
`
`the pressure reducing unit being connected in parallel with
`
`a check valve,
`
`the direction of the tank being the forward
`
`direction of the check valve.
`
`[0009]
`
`A refrigeration apparatus of the invention of a
`
`fourth aspect is characterized by comprising: a high-
`
`temperature-side refrigerant circuit and a low-temperature—
`
`side refrigerant circuit each constituting an independent
`
`refrigerant closed circuit in which a refrigerant
`
`10
`
`15
`
`20
`
`25
`
`
`
`discharged from a compressor is condensed'and then
`
`evaporated to exert a cooling function,
`
`the low—
`
`temperature-side refrigerant circuit having the compressor,
`
`a condenser, an evaporator, and a plurality of intermediate
`
`heat exchangers and a plurality of pressure reducing units
`
`connected in series so that the refrigerant fed.back from
`
`the evaporator circulates, wherein a plurality of types of
`
`non—azeotrdpic mixed refrigerants are introduced, a
`
`condensed refrigerant in the refrigerants fed through the
`
`10
`
`condenser is allowed to.join the intermediate heat
`
`exchanger via the pressure reducing unit, a non—condensed
`
`refrigerant in the refrigerants is cooled by the
`
`intermediate heat exchanger to successively condense the
`
`refrigerant having a lewer boiling point,
`
`the refrigerant
`
`15
`
`having the lowest boiling point is allowed to flow into the
`
`evaporator via the final—stage pressure reducing unit, an
`
`evaporator of the high—temperature-side refrigerant circuit
`
`and the condenser of the low—temperature—side refrigerant
`
`circuit constitute a cascade heat exchanger, and the
`
`evaporator of the low-temperature-side refrigerant circuit
`
`obtains an extremely low temperature,
`
`the refrigeration
`
`apparatus further comprising: a tank connected to a pipe of
`
`the compressor of the low-temperature-side refrigerant
`
`-circuit on a suction side via the pressure reducing unit,
`
`the pressure reducing unit being connected in parallel with
`
`a check valve,
`
`the direction of the tank being the forward
`
`20
`
`25
`
`direction of the check valve.
`
`
`
`[0010] According to the present invention,
`
`the
`
`refrigeration apparatus comprises the refrigerant circuit
`
`in Which the refrigerant discharged from the compressor is
`
`condensed and then evaporated to exert the cooling function,
`
`and the tank connected to the pipe of the compressor on the
`
`suction side via the pressure reducing unit,
`
`the pressure
`
`reducing unit being counected in parallel with the check
`
`valve,
`
`the direction of the tank being the forward
`
`direction of the check valve.
`
`In consequence, during the
`
`stop of the compressor,
`
`the refrigerant in the refrigerant
`
`circuit can quickly be collected in the tank via the check
`
`valve.
`
`[0011] Consequently,
`
`the rise of a pressure in the
`
`refrigerant circuit can be prevented.
`
`In a case where
`
`after the start of the compressor,
`
`the refrigerant is
`
`gradually returned from the tank to the refrigerant circuit,
`
`the starting load of the compressor can be decreased.
`
`[0012] Therefore, when the refrigerant is quickly
`
`10
`
`15
`
`collected in the tank during the stop of the compressor, an
`equilibrium pressure in the refrigerant circuit can quickly
`
`20
`
`be achieved. During the restart of the compressor,
`
`the
`
`compressor can smoothly be restarted without applying any
`
`load to the compress0r.
`In consequence,
`the operation
`efficiency of the compressor can be improved.
`For example.
`
`25
`
`time required for a pull-down operation can be shortened to
`
`improve convenience.
`
`[0013] According to the invention of the second aspect,
`
`
`
`the refrigeration apparatus comprises the high—temperature-
`side refrigerant circuit and.the low—temperature—side
`I
`
`refrigerant circuit each constituting the independent
`
`refrigerant closed circuit in which the refrigerant
`
`discharged from the compressor is condensed and then
`
`evaporated to exert the cooling function.
`
`the evaporator of
`
`the high—temperature-side refrigerant circuit and the
`
`condenser of the low-temperature—side refrigerant circuit
`
`constituting the cascade heat exchanger,
`
`the evaporator of
`
`10
`
`the low-temperature—side refrigerant circuit achieving the
`
`extremely low temperature.
`
`The refrigeration apparatus
`
`further comprises the tank connected to the pipe of the
`
`compressor of the low-temperature—side refrigerant circuit
`
`on the suction side via the pressure reducing unit,
`
`the
`
`15
`
`pressure reducing unit is connected in parallel with the
`
`check valve, and the direction of the tank is the forward
`
`direction of the check valve. Consequently,
`
`in a simple
`
`multi-dimensional refrigerant circuit,
`
`the refrigerant in
`
`the low—temperature—side refrigerant circuit can quickly be
`
`20
`
`collected in the tank via the check valve during the stop
`
`of the compressor of the low—temperature—side refrigerant
`
`circuit.
`
`[0014]
`
`In consequence,
`
`the rise of the pressure in the
`
`low-temperature—side refrigerant circuit can be prevented.
`In a case where after the start of the compressor,
`the
`
`25
`
`refrigerant is gradually returned from the tank to the low-
`
`temperature-side refrigerant circuit via the pressure
`
`
`
`reducing unit,
`
`the starting load of the compressor can be
`
`decreased.
`
`[0015] Therefore, when the refrigerant is quickly
`
`collected in the tank during the stop of the compressor,
`
`the equilibrium pressure in the low-temperature-side
`
`refrigerant circuit can quickly be achieved. During the
`
`restart of the compressor,
`
`the compressor can smoothly be
`
`restarted without applying any load to the compressor.
`
`In
`
`consequence,
`
`the operation efficiency of the compressor can
`
`be improved.
`
`For example,
`
`the time required for the pull—
`
`down operation can be shortened to improve the convenience.
`
`[00l6] According to the invention of the third aspect,
`
`the refrigeration apparatus comprises the compressor,
`
`the
`
`cendenser,
`
`the evaporator,
`
`the plurality of intermediate
`
`heat exchangers and the plurality of pressure reducing
`
`units connected in series so that the refrigerant fed back
`
`from the evaporator circulates, wherein the plurality of
`types of non-azeotropic mixed refrigerants are introduced.
`
`the condensed refrigerant in the refrigerants fed through
`
`the condenser is allowed to join the intermediate heat
`
`exchanger via the pressure reducing unit, and the non—
`
`condensed refrigerant in the refrigerants is cooled by the
`
`10
`
`15
`
`20
`
`intermediate heat exchanger to successively condense the
`
`refrigerant having the lower boiling point, and the
`
`25
`
`refrigerant having the lowest boiling point is allowed to
`
`flow into the evaporator via the final—stage pressure
`
`reducing unit to obtain the extremely low temperature.
`
`The
`
`
`
`' refrigeration apparatus further comprises the tank
`
`connected to the pipe of the compressor on the suction side
`
`via the pressure reducing unit,
`the pressure reducing unit
`is connected in parallel with the check valve, and the
`
`direction of the tank is the forward direction of the check
`
`valve. Consequently,
`
`in a simple multi-stage refrigerant
`
`circuit,
`the refrigerant in the refrigerant circuit can
`quickly be collected in the tank via the check valve during
`
`the stop of the compressor of the refrigerant circuit.
`
`10
`
`[0017] Consequently,
`
`the rise of the pressure in the
`
`refrigerant circuit can be prevented.
`
`In a case where
`
`after the start of the compressor,
`
`the refrigerant is
`
`gradually returned from the tank to the refrigerant circuit,
`
`the starting load of the compressor can be decreased.
`
`15
`
`[0018] Therefore, when the refrigerant is quickly
`
`collected in the tank during the stop of the compressor,
`
`the equilibrium pressure in the refrigerant circuit can
`
`quickly be achieved. During the restart of the compressor,
`
`the compressor can smoothly be restarted without applying
`
`any load to the compressor.
`
`In consequence,
`
`the operation
`
`efficiency of the compressor can be improved.
`
`For example,
`
`the time required for the pull—down operation can be
`
`shortened to improve the convenience.
`
`[0019]_ According to the invention of the fourth aspect,
`
`the refrigeration apparatus comprises the high—temperature-
`
`'side refrigerant circuit and the low—temperaturesside
`
`refrigerant circuit each constituting the independent
`
`20
`
`25
`
`
`
`refrigerant closed circuit in which the refrigerant
`
`discharged from the compressor_is condensed and then
`
`evaporated to exert the cooling function.
`
`The low-
`
`temperature—side refrigerant circuit has the compressor,
`
`the condenser,
`
`the evaporator, and the plurality of
`
`intermediate heat exchangers and the plurality of pressure
`
`reducing units connected in series so that the refrigerant
`
`fed back from the evaporator circulates, wherein the
`
`plurality of types of non—azeotropic mixed refrigerants are
`introduced,
`the condensed refrigerant in the refrigerants
`
`10
`
`fed through the condenser is allowed to join the
`
`intermediate heat exchanger via the pressure reducing unit,
`
`the non—condensed refrigerant in the refrigerants is cooled
`
`by the intermediate heat exchanger to successively condense
`
`the refrigerant having the lower boiling point,
`
`the
`
`refrigerant having the lowest boiling point is allowed to
`
`flow into the evaporator via the final-stage pressure
`
`reducing unit,
`
`the evaporator of the high—temperature—side
`
`refrigerant circuit and the condenser of the low-
`
`temperature—side refrigerant circuit constitute the cascade
`
`heat exchanger, and the evaporator of the low—temperature—
`
`side refrigerant circuit obtains the extremely low
`
`temperature.
`
`The refrigeration apparatus further comprises
`
`15
`
`20
`
`the tank connected to the pipe of the compressor of the
`
`25
`
`low—temperature—side refrigerant circuit on the suction
`
`side via the pressure reducing unit,
`
`the pressure reducing
`
`unit is connected in parallel with the check valve, and the
`
`
`
`direction of the tank is the forward direction of the check
`
`valve. Consequently,
`
`in a multi—dimensional multi—stage
`
`refrigeration apparatus, during the stop of the compressor
`
`of the low—temperature—side refrigerant circuit,
`
`the
`
`refrigerant in the low-temperature-side refrigerant circuit
`can quickly be collected in the tank via the check valve.
`
`[0020]
`
`In consequence,
`
`the rise of the pressure in the
`
`low—temperature-side refrigerant circuit can be prevented.
`
`In a case where after the start of the compressor,
`
`the
`
`10
`
`refrigerant is gradually returned from the tank to the low-
`
`temperature-side refrigerant circuit,
`
`the starting load of
`
`the compressor can be decreased.
`
`[0021] Therefore, when the refrigerant is quickly
`
`collected in the tank dUring the stop of the compressor,
`
`15
`
`the equilibrium pressure in the low-temperature-side
`
`refrigerant circuit can quickly be achieved. During the
`
`restart of the compressor,
`
`the compressor can smoothly be
`
`restarted without applying any load to the compressor.
`
`In
`
`20
`
`consequence,
`the operation efficiency of the compressor can
`be improved. For-example,
`the time required for the pull-
`
`down operation can be shortened to improve the convenience.
`
`BRIEF DESCRIPTION OF THE DRAWINGS
`
`[0074]
`
`FIG.
`
`1 is a perspective view of a refrigeration
`
`25
`
`apparatus to which the present invention is applied;
`
`FIG. 2 is a front view of the refrigeration
`
`apparatus of FIG. 1:
`
`
`
`FIG. 3 is a plan view of the refrigeration
`
`apparatus of FIG. 1;
`
`FIG. 4_is a side view in a state in which a
`
`storage chamber is seen through the refrigeration apparatus
`
`of FIG. 1;
`
`FIG.
`
`5 is a perspective view of the refrigeration
`
`apparatus in a state in which a top panel is opened; and
`
`FIG.
`
`6 is a refrigerant circuit diagram of the
`
`-refrigeration apparatus of FIG. 1.
`
`DESCRIPTION OF THE PREFERRED EMBODIMENT
`[0022]
`An embodiment of the present invention will
`
`hereinafter be described with reference to the drawings.
`
`FIG.
`
`1 is a perspective view of a refrigeration apparatus 1
`
`to which the present invention is applied, FIG. 2 is a
`
`front view of the refrigeration apparatus 1, FIG. 3 is a
`
`plan view of the refrigeration apparatus 1, FIG. 4 is a
`
`side view in a state in which a storage chamber 4 is seen
`
`10
`
`15
`
`through the refrigeration apparatus 1, and FIG. 5-is a
`
`20
`
`' perspective View of the refrigeration apparatus 1 in a
`
`state in which a top panel 5 is opened.
`
`The refrigeration
`
`apparatus 1 of the present embodiment is suitable for
`
`stering, at an extremely low temperature, for example, a
`
`living tissue. a specimen or the like to be stOred at a low
`
`25
`
`Vtemperature for a long time, and a main body of the
`
`apparatus is constituted of an insulating box body 2 which
`
`opens in an upper surface, and a mechanical chamber 3 which
`
`
`
`is positioned by the side of the insulating box body 2 and
`in which a compressor 10 and the like are installed.
`'
`
`[0023] This insulating box body 2 is constituted of an
`
`outer box 6 made of a steel plate and an inner box 7 made
`
`of a satisfactorily thermally conductive metal such as
`
`aluminum,
`
`the boxes having opened upper surfaces.
`
`The
`
`insulating box body is also constituted of a breaker 8
`
`connecting the upper ends of both the boxes 6,
`
`7 to each
`
`other, and an insulating material 9 with which a space
`
`surrounded by the outer box 6,
`
`the inner box 7 and the
`
`breaker 8 is filled by an on—site foam system and which is
`
`made of a polyurethane resin.
`
`The inside of the inner box
`
`7 is the storage chamber 4 having an open upper surface.
`
`[0024]
`
`In the present embodiment, a targeted temperature
`
`(hereinafter referred to as the in-chamber temperature) in
`
`the storage chamber 4 is set to, for example,
`
`-150°C or
`
`less. Therefore,
`
`the insulating box body 2 which separates
`
`the inside of the storage chamber 4 and outside air needs
`
`to have large insulating capability against a set low in-
`
`chamber temperature around 0°C. Therefore,
`
`to secure the
`
`insulating capability only by the insulating material 9
`
`made of the polyurethane resin,
`
`the material has to be
`
`formed to be remarkably thick. There is also a problem
`
`that a sufficient storage amount in the storage chamber 4
`
`10
`
`15
`
`20
`
`25
`
`-cannot be secured with a limited main body dimension.
`
`[0025]
`
`To solve the problem,
`
`in the insulating box body 2
`
`of the present embodiment, vacuum insulating panels 12 made
`
`
`
`of glass wool are arranged in the inner wall surfaces of a
`front wall 6A of the outer box 6, a rear wall GB and a side
`
`wall 6C positioned on a side opposite to a side provided
`
`with the mechanical chamber 3.
`
`The panels are tentatively
`
`fixed with an adhesive double coated tape, and then a space
`
`between both the boxes 6 and 7 is filled with the
`
`insulating material 9 by the on—site foam system.
`
`[0026]
`
`To constitute this vacuum insulating panel 12,
`
`glass wool having insulating properties is received in a
`
`10
`
`container constituted of a multilayered film made of‘
`
`15
`
`20
`
`aluminum, a synthetic resin or the like which does not have
`
`any gas permeability. Afterward, air is discharged from
`
`the container by predetermined vacuum exhaust means, and an
`
`opening of the container is thermally sealed and joined.
`
`In consequence, since the vacuum insulating panel 12 has
`
`the insulating performance,
`
`the thickness dimension of the
`
`insulating material 9 is decreased as compared with a
`
`conventional example, but the same insulating effect can be
`
`obtained.
`
`[0027]
`
`On the other hand, an evaporator (an evaporation
`
`pipe) 62 constituting a refrigerant circuit of a cooling
`
`apparatus R described later in detail is attached to the
`
`-peripheral surface of the inner box 7 on the insulating
`
`material 9 side in a heat exchange manner.
`
`25
`
`[0028] Moreover, as shown in FIGS.
`
`2 and 4,
`
`the upper
`
`surface of the breaker 8 of the insulating box body 2
`
`having the above constitution is formed in a staircase—like
`
`
`
`shape, and an insulating door 13 is provided on the surface
`
`via a packing (not_shown) so that the insulating door is
`
`rotatable around one end.
`
`that is,
`
`the rear end of the door
`
`in the present embodiment by pivotable members 14, 14.
`
`Moreover,
`
`the upper-surface opening of the storage chamber
`
`4 is provided with an openable/closable inner lid 15
`
`constituted of an insulating material. Moreover,
`
`the lower
`
`surface of the insulating door 13 is provided with a
`
`pressing portion configured to protrude downwards.
`
`In
`
`10
`
`consequence,
`
`the pressing portion of the insulating.door 13
`
`presses the inner lid 15 to openably close the upper—
`
`surface opening of the storage chamber 4. Moreover,
`
`the
`
`other end,
`
`that is,
`
`the front end of the insulating door 13
`
`in the present embodiment is provided with a handle portion
`
`15
`
`-16, and the handle portion 16 is operated to open or close
`
`the insulating door 13.
`
`[0029]
`
`On the other hand, by the side of the insulating
`
`box body 2, a front panel 3A, a rear panel (not shown) and
`
`a side panel 33 constituting a side surface on a side
`
`20
`
`opposite to a side provided with the insulating box body 2
`
`form the mechanical chamber 3.
`
`The mechanical chamber 3 of
`
`the present embodiment is provided with a partition plate
`
`17 which divides the inside of the chamber into upper and
`
`lower chambers.
`
`The compressor 10, a compressor 20 and the
`
`25
`
`like constituting the cooling apparatus R as described
`
`above are received and installed under the partition plate
`
`17, and the front panel 3A and the side panel 3B positioned
`
`
`
`under the partition plate 17 are provided with slits 3C for
`
`ventilation.
`
`[0030]
`
`An upper mechanical chamber 18 having an opened
`
`upper surface is constituted above the partition plate 17.
`
`The upperhsurface opening of the upper mechanical chamber
`
`18 is provided with the top panel 5 so that the panel is
`
`rotatable around one end, that is,
`
`the rear end of the
`
`panel in the present embodiment, whereby the upper
`
`mechanical chamber 18 is openably closed.
`
`It is to be
`
`10
`
`noted that a panel positioned on the front surface of the
`
`upper mechanical chamber 18 is an operation panel 21 for
`
`operating the refrigeration apparatus 1.
`
`[0031]
`
`A side surface constituting this upper mechanical
`
`chamber 18 on the insulating box body 2 side is provided
`
`15
`
`with a measurement hole 19. This measurement hole 19 is
`
`extended through the outer box 6,
`
`the insulating material 9
`
`and the inner box 7 constituting the insulating box body 2
`
`so as to communicate with the storage chamber 4 formed in
`
`the insulating box body 2 provided adjacent to the
`
`measurement hole. Through the measurement hole 19. a
`
`temperature sensor can be inserted into the storage chamber
`
`4 from the outside. and a wiring line drawn from the
`
`temperature sensor is connected to an external recording
`
`apparatus main body through the measurement hole 19.
`
`Moreover, a gap between this measurement hole 19 and the
`
`wiring line is closed by a plug 19A constituted of a
`
`sponge-like deformable special material having insulating
`
`20
`
`25
`
`
`
`properties.
`
`It is to be noted that the measurement hole 19
`
`is closed by the plug 19A in an insulating manner in a
`
`state in which the temperature sensor is not attached to
`
`the hole.
`
`-
`
`[0032]
`
`In consequence, when an instrument for measuring
`
`or recording the temperature in the storage chamber 4 is
`
`used,
`
`the top panel 5 provided in the mechanical chamber 3
`
`is opened, and the measuring instrument can be inserted
`into the storage chamber 4 through the measurement hole 19
`
`10
`
`formed in the side surface of the insulating box body 2
`
`positioned in the upper mechanical chamber 18. This can
`
`facilitate an operation of installing the measuring-
`
`instrument in the storage chamber 4 cooled to a
`
`predetermined extremely low temperature.
`
`15
`
`20
`
`[0033]
`
`In particular, unlike a measurement hole provided
`
`in a conventional refrigeration apparatus,
`
`the measurement
`
`hole 19 of the present embodiment is formed in the side
`
`surface of the insulating box body 2 on the mechanical
`
`chamber 18 side. Therefore, even when the refrigeration
`
`apparatus 1 is installed adjacent to the wall of an
`
`installation environment such as the laboratory, or another
`
`device, a space necessary for using the measurement hole 19
`
`does not especially have to be disposed.
`
`In consequence,
`
`-an area required for installing the refrigeration apparatus
`
`25
`
`1 can be decreased, which is suitable for determining the
`
`layout of the laboratory or the like.
`
`[0034] Moreover, since the measurement hole 19 is formed
`
`
`
`in the wall surface of the insulating box body 2 on a side
`
`'adjacent to the mechanical chamber 3,
`
`the vacuum insulating
`
`panels 12 can be provided in the side surface other than
`
`the side surface adjacent to the mechanical chamber 3,
`
`that
`
`is,
`
`the front and rear walls and the side surface of the
`
`insulating box body 2 constituted so as to face the outside
`
`without influencing the forming position of the measurement
`
`hole 19.
`
`In consequence,
`
`the leakage of cold from the
`
`rstorage chamber 4 can be decreased, and the wasting of
`
`10
`
`cooling energy can be suppressed.
`
`[0035] Therefore, even when the inside of the storage
`
`chamber 4 has an extremely low temperature of, for
`
`15
`
`20
`
`example,
`
`-150°C or less as in the present embodiment,
`
`the
`
`insulating performance of the insulating box body 2 itself
`
`can be improved, and the dimension of an insulating wall
`
`can be decreased.
`
`Even when the refrigeration apparatus
`
`has an outer dimension similar to that in a conventional
`
`example, a storage volume in the storage chamber 4 can be
`
`increased. Alternatively, even when the refrigeration
`
`apparatus has the storage volume Similar to that in the
`
`conventional example,
`
`the outer dimension can be decreased.
`
`Even in this case,
`
`the area required for installing the
`
`refrigeration apparatus 1 can be decreased.
`
`the measurement hole 19 of the
`Furthermore,
`[0036]
`present embodiment can be covered with the top panel 5
`
`25
`
`which can openably close the upper-surface opening of the
`
`upper medhanical chamber 18, whereby the appearance of the
`
`
`
`apparatus has a constitution in which the measurement hole
`
`19 is not exposed, and the appearance can be improved.
`
`Moreover, when the top panel 5 is opened, an operation can
`easily be performed with respect to the measurement hole 19,
`and operability can be improved. When the partition plate
`
`17 is removed. another device constituting the cooling.
`
`apparatus R installed under the partition plate 17 can
`
`easily be operated, and the efficiency of a maintenance
`
`operation can be improved.
`
`The mechanical chamber 18 is
`
`10
`
`closed with the top panel 5 in a case other than the case
`
`where the operation is performed with respect to the
`
`measurement hole 19, so that the top panel 5 can be used as
`a side table for an operation, and the panel is convenient
`for an operation of storing articles such as samples in the
`
`'15
`
`storage chamber 4 or taking the articles from the chamber.
`
`[0037]
`
`It is to be noted that in the present embodiment,
`
`the measurement hole 19 is covered with the top panel 5
`
`which closes the upper-surface opening of the upper
`
`mechanical chamber 18, but this is not restrictive, and a
`
`20
`
`lid member for covering the measurement hole 19 or the like
`
`may be provided in the vicinity of the measurement hole 19.
`
`[0038] Next,
`
`the refrigerant circuit of the refrigeration
`
`apparatus 1 of the present embodiment will be described
`
`with reference to FIG. 6.
`
`The refrigerant circuit of the
`
`25
`
`refrigeration apparatus 1 in the present embodiment is
`
`constituted of a two-dimensional two—stage refrigerant
`
`circuit, as a multi-dimensional multistage refrigerant
`
`
`
`circuit,
`
`including independent refrigerant circuits of a
`
`high—temperature—side refrigerant circuit 25 as a first
`
`refrigerant circuit and a low—temperature—side refrigerant
`
`circuit 38 as a second refrigerant circuit.
`
`[0039]
`
`The compressor 10 constituting the high-
`
`temperatureeside refrigerant circuit 25 is a reciprocating
`
`electromotive compressor using a one—phase or three—phase
`
`alternating—current.power source, and a discharge side pipe
`
`10D of the compressor 10 is.connected to an auxiliary
`
`condenser 26.
`
`To heat a storage chamber 4 opening edge and
`
`prevent dew condensation,
`
`this auxiliary condenser 26 is
`
`connected to a refrigerant pipe 27 (hereinafter referred to
`
`as a frame pipe) arranged on the back side of this opening
`
`edge. Moreover,
`
`this frame pipe 27 is connected to an oil
`
`cooler 29 of the compressor 10, and then connected to a
`
`condenser 28. Furthermore,
`
`the refrigerant pipe exiting
`
`from the condenser 28 is connected to an oil cooler 30 of
`
`the compressor 20 constituting the low—temperature-side
`
`10
`
`15
`
`refrigerant circuit 38, and is then connected to a
`
`20
`
`condenser 31.
`
`The refrigerant pipe exiting from the
`
`condenser 31 is connected to an evaporator 34 as an
`
`evaporator portion constituting the evaporator successively
`
`via a drier 32 and a capillary tube 33 as a pressure
`reducing unit.
`An outlet side refrigerant pipe of the
`
`25
`
`evaporator 34 is connected.to an accumulator 35 as a
`
`refrigerant liquid reservoir. and the refrigerant pipe
`
`exiting from the accumulator 35 is connected to a suction
`
`
`
`side pipe 103 of_the compressor 10.
`
`It is to be noted that
`
`the auxiliary condenser 26 and the condensers 28 and 31 in
`
`the present embodiment are constituted as an integral
`
`condenser, and are cooled by a blower 36 for the condenser.
`
`[0040]
`
`The high-temperature-side refrigerant circuit 25
`
`is filled with a refrigerant constituted of R407D and n-
`
`pentane as non—azeotropic refrigerants having different
`
`boiling points.
`
`R407D is constituted of R32
`
`(difluoromethane: CHze). R125 (pentafluoroethane: CHFZCFa),
`
`10
`
`and R134a (1,1,1,2—tetrafluoroethane: CHZFCF3), and a
`
`composition includes 15 wt% of R32, 15 wt% of R125 and 70
`
`wt% of R134a. As to the boiling points of the refrigerants,
`
`R32 has —51.8°C, R125 has -48.57°C and R134a has -26.16°C.
`
`Moreover,
`
`the boiling point of napentane is +36.1°C.
`
`15
`
`[0041]
`
`The high-temperature gas refrigerant discharged
`
`from the compressor 10 is condensed, releases heat and is
`
`liquefied by the auxiliary condenser 26,
`
`the frame pipe 27,
`
`the oil cooler 29,
`
`the condenser 28.
`
`the oil cooler 30 of
`
`the compressor 20 of the low—temperature-side refrigerant
`
`20
`
`circuit 38 and the condenser 31. Afterward, a water
`
`content contained in the refrigerant is removed by the
`
`drier 32, and the pressure of the refrigerant is reduced by
`
`the capillary tube 33.
`
`The refrigerants successively flow
`
`into the evaporator 34 to evaporate the refrigerants R32,
`
`25
`
`R125 and R134a. Then, vaporization heat is absorbed from a
`
`surrounding area to cool the evaporator 34, and the
`
`refrigerant returns to the compressor 10 through the
`
`
`
`accumulator 35 as the refrigerant liquid reservoir.
`[0042] At this time,
`the compressor 10 has a capability
`
`of, for example, 1.5 HP, and the final reaching temperature
`
`of the evaporator 34 which is being operated is in a range
`
`of —27°C to —35°C. At such a low temperature, since n—
`
`pentane of the refrigerant has a boiling point of +36.1°C,
`
`the refrigerant does not evaporate in the evaporator 34 and
`
`still has a liquid state. Therefore,
`
`the refrigerant
`
`hardly contributes to cooling, but the refrigerant has a
`
`function of feeding the lubricant of the compressor 10 and
`
`a mixed water content which cannot completely be absorbed
`
`by the drier 32 back to the compressor 10 in a state in
`
`which the same is dissolved in the refrigerant.
`
`The
`
`refrigerant also has a fUnction of lowering the temperature
`
`of the compressor 10 by the evaporation of the liquid
`
`refrigerant in the compr
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