Patent Application
20130139541
This application claims priority to German Patent Application No. 10 2011 118 761.1, filed Nov. 17, 2011, which is incorporated herein by reference in its entirety.
This application pertains to a heat exchanger for a motor vehicle air conditioning system, which is designed in particular as an internal heat exchanger for increasing the efficiency of the air conditioning system.
Known in the art for increasing the performance and efficiency of motor vehicle air conditioning systems are heat exchangers incorporated inside of air conditioning systems, so-called internal heat exchangers (IHX), which thermally couple a section of the refrigerant circuit running between the evaporator and compressor with a section of the refrigerant circuit running between the capacitor and expansion valve. In this way, the relatively cold refrigerant flowing from the evaporator to the compressor can be used to (pre)cool or supercool the comparatively warm refrigerant being supplied to the expansion device on the high-pressure side of the refrigerant circuit.
For example, DE 10 2005 052 972 A1 describes a double-walled heat exchanger tube with an outer tube and an inner tube, which define a channel between them. The high-pressure refrigerant here flows through the channel, and the low-pressure refrigerant flows through the inner tube.
The geometric dimensions and shapes of the tubes are crucially important for optimizing the way in which such heat exchangers function in the refrigerant circuit. In an existing vehicle package, which offers virtually no space for individually adapting or modifying the outer contour or outer geometry of the heat exchanger, it is relatively difficult to adjust such heat exchangers to prescribed requirements in terms of their heat exchanger capacity on an individual basis, for example specific to the vehicle type.
Accordingly, it may be desirable to provide an improved heat exchanger for a motor vehicle air conditioning system. In addition, other objects, desirable features and characteristics will become apparent from the subsequent summary and detailed description, and the appended claims, taken in conjunction with the accompanying drawings and this background.
According to one exemplary embodiment, provided is an improved heat exchanger for a motor vehicle air conditioning system, which offers a comparatively high heat exchange capacity given prescribed outer dimensions, and which can be adjusted in terms of its heat transfer capacity to various performance requirements, generally without any changes to its outer geometry. Further, it is to be possible to adjust the heat exchanger so as to replace existing heat exchanger configurations, in one example, to prescribed or already existing connections in motor vehicle air conditioning systems.
The heat exchanger provided in this way exhibits at least one inner tube and one outer tube, wherein the at least one inner tube is at least regionally enveloped by the outer tube, forming a gap through which the heat exchanger medium can flow. The inner tube further exhibits at least two tube sections that are at least regionally wound or coiled, as well as nested.
The tube sections can be spiral or helical, in one example, twisted, and in such a case can also be referred to as spiral tube sections.
In a geometrically simple design, the tube sections extend on an imaginary lateral surface of one or more cylinders, which are generally aligned substantially parallel to the outer tube. However, the two tube sections do not absolutely have to trace a lateral surface of an imaginary cylinder, but can also exhibit contours that irregularly deviate from a helical shape, e.g., oval or elliptical as well as nested regions. In this regard, the term wound or coiled tube section as used here also encompasses tube sections of any shape that regionally deviate from a geometric spiral or helical form.
A heat exchanger medium can here flow through the gap formed by the inner tube and outer tube, as well as the inner tube and its tube sections, wherein it is provided in one example, that the gap between the inner tube and outer tube can carry a flow opposite the direction in which the heat exchanger medium flows through the inner tube. The heat exchanger medium, also referred to as the coolant, can be 2,3,3,3-tetrafluoropropene or HFO-1234yf or tetrafluoroethane or R134a.
The at least regionally wound, bent, coiled, spiral or helical configuration of two tube sections makes it possible to increase the overall length and surface of the inner tube lying inside the outer tube as a whole, or variably adjust the latter to disparate requirements with respect to heat exchanger performance. Depending on how densely the tube sections are coiled or wound, the tube length of the tube sections as well as inner tube over which the heat exchanger medium is able to flow can be variably altered, wherein the coiling or winding density indicates a measure for the number of consecutive coils in the tube section in an axial direction.
For example, if a comparatively high heat exchanger performance is required, at least one of the two tube sections can be lengthened in terms of its tube length that is able to carry a flow, but clinched in an axial direction from a geometric standpoint, thereby yielding a shorter axial distance of individual coils as a whole, and hence an elevated coiling density. The heat exchanger medium flowing through the gap between the inner tube and outer tube can advantageously flow completely around the tube sections.
Providing at least two nested tube sections allows the heat exchanger medium flowing through the gap to also flow around or through a region lying radially between the tube sections, so as to further increase a heat exchange performance or capacity. Depending on the configuration of the nested tube sections, the heat exchanger performance of the heat exchanger can be varied by up to about 20% or more.
In one exemplary embodiment, the tube sections, for example, a first and a second tube section, exhibit different curvature radii or helical diameters. Further, the tube sections with a different curvature radius or helical diameter can be arranged concentrically relative to each other. For example, a first tube section viewed in the radial direction can run completely inside a second tube section. Given the same or similar winding density for the first and second tube section, the varying helical diameter yields a somewhat expanded tube length overall for the radially outermost tube section.
If both tube sections are to exhibit roughly the same tube lengths, the inner tube section can exhibit a higher axial winding density relative to the outer one, for example, and thus also have an elevated number of windings or coils.
Because in one example, the outer tube section exhibits a lower winding or coiling density than the inner tube section, the heat exchanger medium flowing around the inner tube can flow toward the inner tube section and away from the latter relatively unimpeded, even in the radial direction.
The two tube sections can be arranged and aligned concentrically to each other, so that the helical or spiral axes of the first and second tube section substantially come to overlap each other. In addition, the longitudinal axes of the tube sections can also coincide with a longitudinal axis of the outer tube, thereby yielding a radially symmetrical design overall for the outer tube and inner tube or for the outer tube and tube sections of the inner tube.
In another exemplary embodiment, there is a direct fluid connection between the tube sections lying inside the outer tube. The tube sections advantageously branch or empty inside the outer tube, so that the heat exchanger for the inner tube exhibits only one inlet or one outlet. This type of embodiment is important in one example, for establishing connections to existing air conditioning system components and integrating the heat exchanger into an existing air conditioning system design. Further, this makes it possible to keep the final assembly of the heat exchanger in the air conditioning system circuit comparatively simple and inexpensive, despite a rather complex internal tube arrangement.
It is here advantageously provided that the inner tube branches into the at least two tube sections downstream from an inlet that passes through the outer tube. The branching of the tube sections here lies inside the outer tube.
In like manner, the two separated tube sections of the inner tube empty into a junction upstream from an outlet of the inner tube that passes through the outer tube. This junction or opening of the two tube sections here also lies completely inside the outer tube. In this regard, even though several tube sections run inside the outer tube, only two tube fairleads need to be provided, at which the inner tube with a single inlet and with only a single outlet passes through the wall of the outer tube.
In another exemplary embodiment, at least one tube section exhibits a changing helical diameter viewed in the axial direction. In one example, it can be provided that the outer, for example second, tube section expand, substantially continuously, on the inlet or outlet side from a comparatively small helical diameter on the outlet or inlet side into an enlarged helical diameter. Viewed in the axial direction, the radially expanding tube section can exhibit a roughly conical outer geometry. Depending on the winding or coiling density of the respective tube section, such a conical progression can specifically alter and influence the flow conditions inside the outer tube.
For example, individual passages or sections that taper in terms of flow can be provided in one example, between the radially expanded outer tube section and the inner tube, e.g., causing the flow rate of the heat exchanger medium to become locally elevated. Further, the variable shape of the at least one tube section in the axial direction can induce or facilitate a targeted swirling of the heat exchanger medium flowing through the gap.
An expanding or tapering helical diameter of at least one tube section can be provided for both the outer and inner tube section. In relation to the axial direction, the respective other tube section can here exhibit a constant helical diameter, or also one that varies in the axial direction. Depending on the required flow conditions and a required heat exchange performance of the heat exchanger, the winding and coiling density of the individual tube sections can remain constant in the axial direction or vary.
If an initially inner tube section exhibits a helical diameter that varies in an axial direction, it can also be provided in one example, that the inner tube section quasi passes through the outer tube section that envelops it like a jacket in the radial direction.
Another exemplary embodiment can also provide that the helical diameter of a tube section increase in the axial direction, while the helical diameter of the other tube section decreases in the axial direction. The tube sections here exhibit a quasi opposite or reverse geometry in relation to the axial direction. For example, while a tube section near the inlet of the inner tube increases from a minimum helical diameter toward the outlet to a maximum spiral tube diameter, precisely the opposite configuration can be provided for the other tube section. The latter can exhibit its maximum helical diameter on the inlet side, and its minimum helical diameter on the outlet side, for example.
In another exemplary embodiment, the first tube section passes by way of a curved segment into the second tube section, which can be reversely situated relative to the first tube section. In one example, it is here provided that the first tube section extends over nearly the entire axial extension of the outer tube, and passes by way of the curved segment into an oppositely aligned second tube section. For example, such an arrangement makes it possible to provide the inlet and outlet for the inner tube on the very same side of the outer tube or heat exchanger.
By contrast, if the inlet and outlet of the inner tube are to be provided at diametrically opposed end sections of the outer tube, the inner tube in another exemplary embodiment can exhibit an additional, substantially straight tube section. This substantially, but not necessarily, straight tube section connects either the inlet or outlet of the inner tube with the first and/or second tube section. As an alternative, the substantially straight tube section can connect the first and second tube section with each other in terms of flow. The end sections of the straight tube section here in one example, pass over into respective curved segments, which in turn pass over into the first and second tube sections, generally without branching.
The substantially straight tube section can here run either completely inside the nested tube sections, or extend radially outside both tube sections.
Depending on whether the straight tube is provided between the two tube sections or immediately adjacent to just one end section of a tube section in terms of flow, aligned or opposed flow conditions arise in the individual, nested tube sections, so that the heat exchange performance of the heat exchanger can be tailored to prescribed requirements.
Another exemplary embodiment can further provide that an inlet and outlet of the inner tube pass through the outer tube on the very same side, or the very same end face of the outer tube. Such a configuration helps to save on space when positioning the heat exchanger, and can assist in optimizing how the installation space of the vehicle is divided up. In addition, this embodiment makes it possible to design the face of the outer tube facing away from the inlet and outlet to be largely free of penetration, so that a duct for the inlet and outlet of the inner tube through the outer tube need only be provided on one face of the outer tube.
In this exemplary embodiment, a non-branching configuration of the inner tube can also prove advantageous. This holds true in one example, when the inlet and outlet are connected in terms of flow with respectively oppositely aligned tube sections, which merge into each other by way of a curved section in the area of the side of the outer tube facing away from the inlet or outlet.
In another exemplary embodiment, the outer tube is designed as a low-pressure line, and the inner tube or its tube sections are provided as high-pressure lines. As a consequence, predominantly a compressed fluid flows through the inner tube, while a predominantly gaseous heat exchanger medium flows through the outer tube or the gap formed between the outer tube and heat exchanger tubes.
As a variation of the above, it can further be provided that the outer tube be designed as the high-pressure line, and the inner tube as the low-pressure line, and correspondingly be connected in terms of flow with the components of the refrigerant circuit.
A cross sectional geometry of the inner tube or its tube sections can exhibit any contour corresponding to the requirements. The inner tube can be completely or sectionally designed as a circular tube, a square or multi-sided tube, as well as exhibit an oval or elliptical cross section.
It is further provided for a heat exchanger exhibiting a largely tubular and cylindrical outer contour that opposing end sections of the outer tube can be arranged downstream from an evaporator and upstream from a compressor in the refrigerant circuit of a motor vehicle air conditioning system. Accordingly provided for the opposing end sections of the inner tube is an arrangement upstream from an expansion device and downstream from a capacitor in the refrigerant circuit of the air conditioning system.
It here generally holds true that the low-pressure line(s) is/are designed to couple the evaporator and compressor in terms of flow, while the high-pressure line(s) is/are designed to couple the capacitor and expansion device of the refrigerant circuit of the air conditioning system in terms of flow.
In another exemplary embodiment, the present disclosure further relates to a motor vehicle air conditioning system that exhibits a refrigerant circuit with at least a compressor, a capacitor, an expansion device as well as an evaporator, which are fluidically and serially interconnected by corresponding lines of the refrigerant circuit, and coupled together in terms of flow to circulate the refrigerant.
The refrigerant circuit here further exhibits a previously described, generally tubular heat exchanger, which induces a heat exchange between the low-pressure side lying downstream from the evaporator and high-pressure side of the refrigerant circuit lying upstream from the expansion device.
In another exemplary embodiment, the present disclosure further relates to a motor vehicle, which exhibits an air conditioning system configured in this way, or at least a heat exchanger of the kind described previously.
A person skilled in the art can gather other characteristics and advantages of the disclosure from the following description of exemplary embodiments that refers to the attached drawings, wherein the described exemplary embodiments should not be interpreted in a restrictive sense.
The various embodiments will hereinafter be described in conjunction with the following drawing figures, wherein like numerals denote like elements, and wherein:
The following detailed description is merely exemplary in nature and is not intended to limit the present disclosure or the application and uses of the present disclosure. Furthermore, there is no intention to be bound by any theory presented in the preceding background or the following detailed description.
The motor vehicle air conditioning system 1 schematically depicted on
The high-temperature heat exchanger medium exposed to a comparatively high pressure is supercooled upstream from the expansion device 18 by the low-pressure and low-temperature heat exchanger medium flowing in the opposite direction in the heat exchanger 10. This internal heat exchange in the refrigerant circuit 12 makes it possible to improve the efficiency of the motor vehicle air conditioning system 1.
The internal heat exchanger 10 of a motor vehicle air conditioning system 1 shown as an example on
As a consequence, the outer tube 30 is allocated to the low-pressure side of the refrigerant circuitl2, while a heat exchanger medium exposed to a high pressure can flow through the inner tube 32 in the opposite direction.
In the exemplary embodiment according to
Viewed in the axial direction 78, a first tube section 36 here exhibits a constant helical diameter in the radial direction, thereby yielding an overall cylindrical lateral surface for the inner tube section 36. Much the same holds true for the second, outer tube section 35, which overall exhibits a larger helical diameter 37 than the first tube section 36. The second tube section 35 also exhibits a roughly cylindrical imaginary lateral surface.
The helical diameter 37 of the outer tube section of the inner tube can measure between about 80% and about 98% of the inner diameter of the outer tube, generally between about 90% and about 95%, which applies to all depicted exemplary embodiments. The (inner) tube section of the inner tube nested therein can exhibit a diameter lying between about 40% and about 60% of the inner diameter of the outer tube.
In the exemplary configuration according to
Let it further be noted with respect to all exemplary embodiments depicted in
The branching 33 and junction 34 of the tube sections 35, 36 causes the pressurized heat exchanger medium to flow through the latter in the same direction, for example from left to right on
The exemplary embodiments described below and depicted in
The heat exchanger 40 according to
In the cross section according to
In the exemplary embodiments according to
The coils 56′, 56″ lying downstream from the branching 53 exhibit a helical diameter that becomes larger as the distance away from the branching 53 increases. In this regard, the first tube section 56 exhibits a conically expanding lateral surface in the axial direction 78 relative to the direction of flow for the heat exchanger medium, while the other tube section 55 exhibits a correspondingly conically tapering lateral surface. The tube sections 55, 56 here mutually pass through each other, so that the first tube section 56 lies inside the second tube section 55 on the inlet side, while the reverse constellation arises on the outlet side, in which the first tube section 56 comes to lie radially outside the second tube section 55.
The exemplary embodiment shown in
The first tube section 65 winds nearly completely around the straight tube section 63, and at the other end, i.e., near the inlet 22, passes over by way of another curved segment 66 into the second, outer tube section 67. The latter envelops both the straight tube section 63 and the inner first tube section 63 in the circumferential direction, and finally empties out into the outlet 24. Since the two tube sections 65, 67 are directly connected in terms of flow via a curved segment 66, the heat exchanger medium flows through the two nested tube sections 65, 67 in an opposite direction with the heat exchanger 60 in operation.
The exemplary embodiment according to
In such an arrangement, the pressurized heat exchanger medium can flow through both tube sections 75, 77 in the same direction relative to the axial direction 78. It is here further provided that the inlet 22 empties directly into the radially outer tube section 77, and, at the opposite end of the heat exchanger 70 near the outlet, the respective tube section 77 passes over via a curved segment 74 into a substantially straight tube section 73, by way of which the tube section can flow back on the left side of the heat exchanger 70 depicted on
The heat exchanger medium is there supplied to the inner tube section 75 via another curved segment 76, so that both tube sections 77, 75 eventually are sequentially connected with each other in terms of flow, but geometrically lie one inside the other. Further, the straight tube section 73 shown in
As described, the inner tube 32, 42, 52 in
The heat exchanger 80 depicted on
Production is simpler and tends not involve as many errors in the heat exchanger 80 depicted on
The varying exemplary embodiments of diverse inner tubes 32, 42, 52, 62, 72, 82 for an internal heat exchanger 10, 40, 50, 60, 70, 80 in a motor vehicle air conditioning system 1 depicted in particular in
All of the exemplary embodiments shown here in conjunction with modifications thereto described only in words can involve being able to individually adapt the heat exchange performance of the respective heat exchangers 10, 40, 50, 60, 70, 80 to the varying requirements of differently configured air conditioning systems 1, while retaining prescribed outer dimensions.
While at least one exemplary embodiment has been presented in the foregoing detailed description, it should be appreciated that a vast number of variations exist. It should also be appreciated that the exemplary embodiment or exemplary embodiments are only examples, and are not intended to limit the scope, applicability, or configuration of the present disclosure in any way. Rather, the foregoing detailed description will provide those skilled in the art with a convenient road map for implementing an exemplary embodiment, it being understood that various changes may be made in the function and arrangement of elements described in an exemplary embodiment without departing from the scope of the present disclosure as set forth in the appended claims and their legal equivalents.
| Number | Date | Country | Kind |
|---|---|---|---|
| 102011118761.1 | Nov 2011 | DE | national |
