FR2863043A1 - HEAT EXCHANGER FOR REFRIGERANT CYCLE SYSTEM - Google Patents

Abstract

A heat exchanger (20) for a refrigerant cycle system in a vehicle includes multiple tubes (21) and head manifolds (24) which are communicated with the tubes (21) at parts of longitudinal end (21a) of the tube (21). A resistance to withstand the pressure of the tube (21) is set lower than that of the head manifold (24) which has a larger volume than that of each tube (21). Therefore, the tube (21) breaks earlier than the head manifold (24) when a refrigerant pressure in the heat exchanger exceeds the pressure withstand resistance of the tube (21).

Description

HEAT EXCHANGER FOR REFRIGERANT CYCLE SYSTEM

Description

  The present invention relates to a heat exchanger for a vehicle refrigerant cycle system.

  In general, a heat exchanger (for example a gas cooler) for a vehicle air conditioner (i.e. a refrigerant cycle system), in which a refrigerant circulates, is provided with tubes and multiple fins. The tubes and the fins are stacked. Each of the fins is disposed between the adjacent tubes. Two head collectors are provided for communicating with the tube at the tube end portions in a longitudinal direction of the tube. Referring to JP-2001-66 088A, for example, an upper sealing unit and a lower sealing unit are provided for sealing the upper and lower end portions of the head collector in a longitudinal direction of the collector. of head, respectively. Here, the breaking strengths of the upper sealing unit and the head collector are adjusted to be larger than those of the lower sealing unit.

  As a result, the lower seal unit will break earlier than the upper seal unit and the head manifold, when a refrigerant pressure in the heat exchanger becomes too high and exceeds the breaking strength. of the lower sealing unit. In general, the gas cooler is disposed in a motor compartment of a vehicle. In this case, the refrigerant from the gas cooler and the broken parts of it will disperse down to the lower part of the engine compartment.

  However, for a heat exchanger such as a heater or an evaporator which is disposed in a passenger compartment of the vehicle, the broken broken parts of the heat exchanger will meet the lower half (for example the feet) of the passengers . Refrigerant such as carbon dioxide (CO2) may leak into the passenger compartment.

  In view of the above problems, it is an object of the present invention to provide a heat exchanger for a vehicle refrigerant cycle system which causes less damage to passengers even when the refrigerant pressure becomes too high in this one.

  According to the present invention, a heat exchanger for a vehicle refrigerant cycle system comprises multiple tubes in which a refrigerant circulates, and head collectors communicated with the tubes at the end portions of the tubes. in a longitudinal direction of the tube. The tube has a lower resistance than the head collector to withstand the pressure.

  As a result, the tube will rupture sooner than the head manifold, when a refrigerant pressure in the heat exchanger will increase to the point of exceeding the pressure resistance of the tube. As the tube has a smaller volume than the head collector, the pouring refrigerant is decreased. As a result, it becomes easier to arrange the heat exchanger in a passenger compartment of the vehicle.

  Preferably, each of the tubes comprises at least one partition wall for defining at least two refrigerant conduits in the tube. In addition, the wall wall has a greater resistance to pressure resistance than an outer wall of the tube.

  As a result, the outer wall will break earlier than the partition wall, when the pressure of the refrigerant in the heat exchanger exceeds the pressure resistance of the outer wall. At this time, the multiple refrigerant lines in the tube remain separated from each other.

  Preferably, the head collector is provided with multiple refrigerant conduits in which the refrigerant circulates. Two end portions of the head collector in the width direction of the head collector may have a lower pressure-holding resistance than an intermediate portion of the head collector between adjacent refrigerant conduits.

  As a result, the lateral end portion will rupture earlier than the middle portion of the head collector, when the refrigerant pressure: will exceed the pressure holding resistance of the lateral end portion. As a result, the multiple refrigerant lines in the head collector remain separated from one another.

  Preferably, the heat exchangers disposed outside the passenger compartment may have lower resistance to withstand the pressure than the heat exchangers inside the passenger compartment.

  As a result, the heat exchanger outside the passenger compartment will break earlier than inside the passenger compartment, when the refrigerant pressure exceeds the pressure resistance of the passenger compartment. heat exchanger.

  The foregoing and other objects, features, and advantages of the present invention will become more apparent from the following detailed description, with reference to the accompanying drawings, in the drawings: Figure 1 is a simplified view Referring to a first embodiment of the present invention, FIG. 2 is a perspective view showing a heat exchanger according to the first embodiment. FIG. 3 is a cross-sectional view of an embodiment of the present invention. Heat exchanger tube according to the first embodiment, and Figure 4 is a cross-sectional view of a head collector of the heat exchanger according to a second embodiment of the present invention.

  The preferred embodiment will be described with reference to the accompanying drawings.

  [PREFERRED EMBODIMENT] The first embodiment of the present invention will be described with reference to Figs. 1-3. A refrigerant cycle system 1 for a vehicle includes a compressor 10, an interior radiator 20, an exterior radiator 30, a decompression unit 40, an evaporator 50, a receiver 60 and an indoor heat exchanger 70. These are connected through a refrigerant pipe 80 to form a closed circuit of a refrigerant cycle.

  The inner radiator 20 and the evaporator 50 are disposed in an air conditioner block la which is mounted in a passenger compartment (for example the dashboard) of the vehicle. The compressor 10, the external radiator 30, the decompression unit 40, the receiver 60 and the indoor heat exchanger 70 are positioned in a motor compartment, which is disposed outside the passenger compartment of the vehicle. Carbon dioxide (CO2) is commonly used as a refrigerant in the refrigerant cycle system 1, in which a high pressure side CO2 pressure exceeds the critical CO2 pressure.

  The compressor 10 is driven by a motor in the vehicle via an electromagnetic clutch (not shown) or the like, so that the refrigerant is sucked into the compressor 10 in which the refrigerant is compressed to present a high pressure ( for example 10 MPa) and a high temperature.

  The inner radiator 20 is a heat exchanger in which the high temperature refrigerant discharged from the compressor 10 radiates heat to the air that is heated and blown into the passenger compartment.

  The outer radiator 30, disposed at a front portion of the engine compartment, is a heat exchanger (i.e. a gas cooler) in which the refrigerant discharged from the inner radiator 20 radiates heat to the outside air to be cooled. A cooling fan (not shown), driven by an electric motor or the like, is provided in the outer radiator 30 to improve the cooling volume of the outer radiator 30.

  In the indoor heat exchanger 70, the refrigerant discharged from the outer radiator 30 is further cooled by the gaseous refrigerant discharged from the receiver 60 (described later).

  The decompression unit 40 is an expansion valve for decompressing the discharged refrigerant from the indoor heat exchanger 70, so that the pressure (at about 4 MPa) and the refrigerant temperature are reduced to become a refrigerant. two-phase liquid-gas refrigerant.

  Thus, the two-phase liquid-gas refrigerant flows in the evaporator 50. The evaporator 50 is a heat exchanger, in which the liquid refrigerant from the decompression unit 40 evaporates by absorbing heat from the heat sink. air which is blown by an electric fan (not shown). So the air is cooled to be blown into the passenger compartment.

  The receiver 60 is an accumulator, in which the two-phase liquid-gas refrigerant discharged from the evaporator 50 is separated into two phases and the liquid refrigerant is temporarily stored.

  In the indoor heat exchanger 70, the gaseous refrigerant discharged from the receiver 60 exchanges heat with the refrigerant discharged from the external radiator 30, which is further cooled to flow through the evaporator 50 via the decompression unit. 40. As a result, the value of the enthalpy change Ai of the refrigerant in the evaporator 50 is increased to improve the cooling volume of the evaporator 50.

  As described above, the refrigerant cycle system 1 is provided with multiple heat exchangers 20 and 50 having a similar design comprising tubes, vanes, multiple head collectors and the like. As an example, the structure of the inner radiator 20 will be described with reference to Figures 2 and 3.

  Referring to FIG. 2, the inner radiator 20 comprises multiple tubes 21, multiple fins 22, side plates 23 and head collectors 24, all being made of aluminum or an aluminum alloy and being integrally welded by brazing or the like.

  Referring to Figure 3, each of the tubes 21 has an outer wall 21c for defining a refrigerant conduit having a cross section shaped flattened ellipse. In addition, at least one partition wall 21d (four partition walls in FIG. 3) are disposed in the tube 21, so that the refrigerant duct in the tube 21 is separated into multiple refrigerant conduits 21b. Each duct 21b has a square cross section. The multiple refrigerant conduits 21b are arranged parallel to each other to extend in a longitudinal direction of the tube 21.

  Each of the fins 22 is formed by a thin strip plate so as to have a corrugated shape in the longitudinal direction (direction of the left to the right shown in Figure 2) of the tube 21. The fins 22 and the tubes 21 are stacked in a stacking direction corresponding to the direction from top to bottom shown in Figure 2. Each of the fins 22 is disposed between the adjacent tubes 21. The side plates 23 for reinforcing the inner radiator 20 are disposed outside the fins 22, which are positioned on the outermost sides in the stacking direction of the stack in the inner radiator 20.

  The head collectors 24 communicate with each of the multiple tubes 21 at both end portions 21a of the tube 21 in the longitudinal direction of the tube, respectively.

  The multiple connectors 25 are attached to the first head manifold 24 (head collector on the left side in Fig. 2) to be connected to the refrigerant pipe 80 (not shown in Fig. 2), in which the refrigerant flows as it enters. and leaving the inner radiator 20.

  In the refrigerant cycle system 1 which is provided with the multiple heat exchangers having the structure similar to that described above, the cycles of refrigerant cycle to be compressed, cooled, decompressed and evaporated, so that the air in the block of air conditioner is heated by the inner radiator 20 or is cooled by the evaporator 50, being then blown into the passenger compartment.

  In the refrigerant cycle system 1, the pressure (about 10 MPa) of the refrigerant on the high pressure side (i.e. refrigerant compressed by the compressor 10) exceeds the critical refrigerant pressure. Accordingly, if components of the refrigerant cycle system 1 break due to the high refrigerant pressure, refrigerant leakage and dispersion of the broken parts of the elements must be sufficiently restricted.

  In general, the heat exchanger has a design pressure, which is higher than the refrigerant pressure therein, to provide a safety margin. If the refrigerant pressure in the heat exchanger increases beyond the design pressure, the heat exchanger will be destroyed. In this case, the design pressure is defined as the resistance to pressure of the heat exchanger. In a similar manner, a resistance to pressure of the tube 21, head collectors 24 or the like may also be specified.

  According to this embodiment, in the heat exchanger (for example the inner radiator 20), the resistance to the pressure of the tube 21 is lower than that of the head collector 24. Thus, the tube 21 is will break earlier than the head collector 24, when the pressure of the refrigerant in the inner radiator 20 exceeds the resistance to the pressure of the tube 21. As the tube 21 has a smaller volume than the head collector 24, the refrigerant that gushes is reduced. So, a burst is decreased. As a result, the damage to the passengers can be minimized even in the case where this heat exchanger is disposed inside the passenger compartment.

  In addition, different parts constituting the tube 21 may have different compressive strengths. In this case, a resistance to the pressure of the outer wall 21c is set to be lower than that of the partition wall 21d. Thus, for example, the thickness (indicated by X in Fig. 3) of the outer wall 21c can be set lower than the thickness (indicated by Y in Fig. 3) of the partition wall 21d. Specifically, the thickness X is a sectional dimension in the direction from top to bottom and the thickness Y is a sectional dimension in the direction from left to right, with reference to FIG. 3 which represents the cross-section of the tube 21.

  As a result, the outer wall 21c will be broken earlier than the partition wall 21d when the refrigerant pressure in the heat exchanger 20 exceeds the resistance to pressure of the outer wall 21c. In this case, as shown in FIG. 3, the multiple refrigerant lines 21b in the tube 21 remain separated from each other, so that the refrigerant leaks through the broken outer wall 21c of the separated refrigerant duct with a volume smaller. As a result, bursting can be reduced. In the case where carbon dioxide (CO2) is used as the refrigerant, the leaking CO2 will be decompressed and cooled to dry ice, so that the broken part (for example an outer arm 21c) is easily reduced when the burst (zone of the broken part) is weak. As a result, the CO2 fluid flow rate is decreased.

  [SECOND EMBODIMENT] In the second embodiment of the present invention, restriction of bursting based on the head collector 24 of the inner radiator 20 (heat exchanger) will be described.

  As indicated in FIG. 4, the head collector 24 is provided with a collector element 24b, an intermediate element 24c and a stamping element 24d for fixing the collector element 24b and the intermediate element 24c, which are stacked. Thus, all the elements 24b, 24c and 24d are welded together by brazing or otherwise.

  The collector member 24b is provided with multiple protruding portions (eg two) to define the multiple refrigerant conduits 24a in which the refrigerant circulates. The multiple protuberant portions (refrigerant conduits 24a) are arranged to be parallel to one another by extending in the longitudinal direction (for example the stacking direction of the tubes 21) of the head collector 24.

  As described above, head collectors 24 communicate with each of multiple tubes 21 at both end portions 21a of tube 21, respectively. The holes of the multiple tubes 24c1 and the tube holes 24d1 are respectively provided in the intermediate member 24c and the stamping member 24d at positions corresponding to the end portions 21a of the tube 21. Each of the end portions 21a is inserted through the tube hole 24c1 and the tube hole 24d1 of the corresponding position, so that the refrigerant lines 24a in the head collectors 24 are placed in communication with the refrigerant lines 21b in the tubes 21.

  The opening portions at the two longitudinal end portions 40 of the head collector 24 in the longitudinal direction of the head collector 24 are respectively sealed by sealing units 24e (shown in FIG. 2) by brazing or otherwise .

  In the head collector 24, two lateral end portions of the head collector 24 in the width direction of the head collector 24, may have a lower resistance to pressure resistance than an intermediate portion of the head collector 24 disposed between the adjacent refrigerant conduits 24a. As shown in Fig. 4, the side end portions are indicated by A, and the intermediate portion of the head collector 24 is indicated by B. Thus, for example, when the head collector 24b, 24c and 24d elements 24 are joined together by brazing, the brazing zone (for example the zone of application of the brazing material) at the intermediate portion B will be greater than that at the lateral end portions A, so that that the intermediate portion B has a greater resistance to withstand pressure (design pressure).

  As a result, the lateral end portions A will break off earlier than the intermediate portion B when the refrigerant pressure in the inner radiator 20 exceeds the resistance to pressure of the side end portions A. At this time, the multiple refrigerant lines 24A remain separated from each other, and the refrigerant leaks from the separate refrigerant duct having a smaller volume. So, the burst is decreased.

  In addition, a resistance to pressure of the sealing unit 24e is provided greater than for the elements 24c, 24b and 24d. As a result, the elements 24c, 24b and 24d will break off earlier.

  [THIRD EMBODIMENT] In the embodiments described above, the compressive strength resistors of the elements (i.e. the tubes 21 and the head collector 24) constituting a heat exchanger (e.g. interior radiator 20) are set differently. In the third embodiment, the resistance to pressure of the various heat exchangers 20, 30, 50 and 70, which constitute the refrigerant cycle system 1, can be adjusted.

  In particular, the compressive strength resistances of the heat exchangers disposed outside the passenger compartment, including the external radiator 30 and the indoor heat exchanger 70 are set lower than those of the heat exchangers inside the passenger compartment, comprising the inner radiator 20 and the evaporator 50.

  As a result, the heat exchangers 70 and 30 will break off earlier than the heat exchangers 20 and 50 when the refrigerant pressures in the heat exchangers 70 and 30 increase to the point of exceeding their resistance to pressure. So the damage to passengers can be restricted.

  Among the heat exchangers outside the passenger compartment, the pressure of the refrigerant circulating in the indoor heat exchanger 70 (ie the low pressure side) is lower than that in the external radiator 30 (i.e., the high pressure side). Thus, the resistance to pressure of the indoor heat exchanger 70 is set to a lower value than that of the outer radiator 30, so that the indoor heat exchanger 70 will break earlier than the outer radiator 30 when the pressure of the refrigerant in the indoor heat exchanger 70 will rise to the point of exceeding its resistance to pressure resistance.

  Similarly, among the heat exchangers inside the passenger compartment, the pressure of the refrigerant flowing in the evaporator 50 (i.e., the low pressure side) is lower than that in the the inner radiator 20 (i.e., the high pressure side). Thus, the resistance to the pressure of the evaporator 50 is set to a lower value than that of the inner radiator 20, so that the evaporator 50 will break earlier than the inner radiator 20 when the refrigerant pressure in the evaporator 50 will increase to the point of exceeding the design pressure thereof.

  Accordingly, in a burst of the refrigerant cycle system 1 having the structure described above, the low pressure refrigerant in the low pressure side heat exchanger will spring earlier. With the refrigerant leak, the refrigerant pressure in the refrigerant cycle system 1 will gradually decrease. Thus, the burst will be decreased.

[OTHER EMBODIMENTS]

  Ethylene, ethane, nitric oxide or the like may also be used as a refrigerant in the refrigerant cycle system 1 instead of CO2.

  The partition wall 21d of the tube 21 may also be provided with a reinforcing member to obtain a larger design pressure (resistance to pressure).

  In a similar manner, the intermediate portion of the head collector 24 may also be provided with a reinforcing member to increase the resistance to pressure of the intermediate portion.

  In addition, the head collector 24 can also be integrally formed by a header plate to define a refrigerant conduit. In addition, at least one partition element is disposed in the head collector 24 to separate the refrigerant conduit into multiple refrigerant conduits. In this case, a reinforcing member may also be attached to the partition member to increase its resistance to pressure. Alternatively, the thickness of the partition member may be adjusted larger than that of the lateral end portion of the head collector 24. In this case, the two thicknesses represent a longitudinal sectional dimension of the head collector 24. .

  In addition, among the heat exchangers of the refrigerant cycle system 1, the heat exchanger, which has a smaller rupture zone during a burst, may be provided to have a lower resistance to pressure resistance. As a result, the heat exchanger having the smallest break zone breaks earlier, so that the refrigerant will gradually leak and the refrigerant pressure in the heat exchanger will be decreased, thereby minimizing bursting.

Claims (15)

  A device (20, 30, 50) for a refrigerant cycle system (1) in a vehicle, comprising a first component and a second component connected to each other for the circulation of refrigerant therethrough. and having different compressive strengths, characterized in that the first component has a lower compressive strength than the second component and is provided in a location where failure thereof causes less damage. to the vehicle passengers than the second component.   The device (20, 30, 50) according to claim 1, wherein: the first component comprises a plurality of tubes (21) in which a refrigerant circulates, the tubes (21) being arranged parallel to one another, and the second component comprises a head collector (24) in communication with the tubes (21); and each of the tubes (21) has a lower resistance to pressure than that of the head collector (24), so that the tube (21) breaks earlier than the head collector (24) when a refrigerant pressure exceeds the resistance to pressure of the tube (21).   The apparatus (20, 30, 50) according to claim 2, wherein: the head collector (24) has a plurality of refrigerant lines (24a) in which the refrigerant circulates, and the head collector (24). has intermediate portions (B) disposed between the adjacent refrigerant conduits (24a), the intermediate portions (B) having a greater resistance to pressure resistance than that of the two lateral end portions (A) of the head collector (24) in a width direction of the head collector (24).   4. Device (20, 30, 50) according to claim 2 or 3, 40 wherein the tube (21) has an outer wall (21c) for defining a refrigerant duct in which the refrigerant circulates, and at least one wall partition (21b) for separating the refrigerant duct into at least two refrigerant ducts (21b).   The device (20, 30, 50) according to claim 4, wherein the outer wall (21c) has a lower resistance to pressure resistance than that of the partition wall (21d).   6. Device (20, 30, 50) according to claim 5, wherein the partition wall (21d) has a greater thickness than that of the outer wall (21c).   The device (20, 30, 50) according to claim 6, wherein the partition wall (21d) comprises a reinforcing member for reinforcing the partition wall (21d).   The apparatus (20, 30, 50) according to claim 1, further comprising: a plurality of tubes (21) in which a refrigerant circulates, the tubes (21) being arranged parallel to one another, and a collector of head (24) in communication with the tubes (21), the head collector (24) having a plurality of refrigerant conduits (24a) in which the refrigerant circulates, wherein the head collector (24) has intermediate portions ( B) as a second component disposed between the adjacent refrigerant conduits (24a), the intermediate portions (B) having a greater resistance to pressure resistance than that of the two lateral end portions (A) of the head collector (24) as the first component in a width direction of the head collector (24).   The device (20, 30, 50) according to claim 8, wherein: the head collector (24) has a plurality of protruding portions for defining the refrigerant conduits (24a).   The device (20, 30, 50) according to claim 8 or 9, wherein: the head collector (24) comprises at least two elements (24b to 24d) which are joined together, and a junction zone at the level of the lateral end portion (A) of the head collector (24) is smaller than a junction area at the intermediate portion (B) of the head collector (24).   11. Device (20, 30, 50) according to claim 8 or 9, wherein the intermediate portion (B) of the head collector (24) comprises a reinforcing member for reinforcing the intermediate portion (B).   The device (20, 30, 50) according to claim 10, wherein: the head manifold (24) further comprises sealing units (24e) for sealing two longitudinal end portions of the head collector ( 24) in a longitudinal direction of the head collector (24), and the sealing units (24e) have a greater resistance to pressure resistance than that of the elements (24b - 24d).   13. Device (20, 30, 50) according to any one of claims 1 to 12, wherein the refrigerant is one of carbon dioxide, ethylene, ethane and nitric oxide.   The device (20, 30, 50) according to claim 1, wherein: the device (20, 30, 50) is a heat exchanger having a head collector (24); the first component comprises two lateral end portions (A) of the head collector (24) in a direction of the width of the head collector (24); and the second component comprises intermediate portions (B) disposed between the lateral end portions (A) in the width direction.   The device (20, 30, 50) according to claim 1, wherein: the device (20, 30, 50) is a heat exchanger having a tube (21); the first component comprises an outer wall (21c) for defining a refrigerant duct in which the refrigerant circulates, and the second component comprises a partition wall (21d) for separating the refrigerant duct into at least two refrigerant ducts. (21b); and the partition wall (21d) has a thickness greater than that of the outer wall (21c).