Patent Application
20100155012
This invention relates to the field of air conditioning loops cooperating with a heating, ventilation and/or air conditioning system of a motor vehicle. It relates to a combined device associating an internal heat exchanger with an accumulator involved in such a loop. It also relates to an air conditioning loop including such a combined device.
Motor vehicles are commonly equipped with a heating, ventilation and/or air conditioning system in order to regulate the aerothermal parameters of the air contained in the vehicle interior. Such a system cooperates with an air conditioning loop in order to cool the air flow before it is discharged from the casing to the vehicle interior. Said loop includes a plurality of elements in which a coolant, such as a supercritical fluid, in particular carbon dioxide known as R744, circulates. These elements include at least one compressor, a gas cooler, an internal heat exchanger, an expansion member, an evaporator and an accumulator.
The coolant circulates from the compressor to the gas cooler, then through a “high-pressure” branch of the internal heat exchanger, then to the expansion member, then through the evaporator, then to the accumulator, and finally through a “low-pressure” branch of the internal heat exchanger, in order to return to the compressor.
The compressor is intended to receive the coolant in the gaseous state and to compress it in order to bring it to high pressure. The gas cooler is capable of cooling the compressed coolant, at a relatively constant pressure, by transferring the heat to the environment. The expansion member is capable of reducing the pressure of the coolant leaving the gas cooler by bringing it at least partially to the liquid state. The evaporator is suitable for converting the coolant from the gaseous state to the liquid state coming from the expansion member, at a relatively constant pressure, by drawing heat in said air flow passing through the evaporator. The vaporized coolant is then suctioned by the compressor. These arrangements are such that the coolant is at high pressure inside the “high-pressure” branch of the internal heat exchanger while it is at low pressure inside the “low-pressure” branch of the internal heat exchanger.
The air conditioning loop includes a “high-pressure” line that begins at the outlet of the compressor and ends at the inlet of the expansion member, according to a direction of circulation of the coolant inside the air conditioning loop, in which the gas cooler and the “high-pressure” branch of the heat exchanger are inserted between these two points.
The air conditioning loop also includes a “low-pressure” line that beings at the outlet of the expansion member and ends at the inlet of the compressor, according to the direction of circulation of the coolant inside the air conditioning loop, in which the evaporator, the accumulator and the “low-pressure” branch of the heat exchanger are inserted between these two points.
The accumulator performs a function of separation between a gaseous phase and a liquid phase of the coolant. To this end, the accumulator comprises a separation area dedicated to this function. The accumulator also performs a function of storing a circulating load of coolant according to the conditions of use of the air conditioning loop. For this, the accumulator comprises an area for accumulation of the coolant in liquid state, which the accumulation area collects from the evaporator. In general, the accumulator consists of a chamber housing the separation area and the accumulation area, and the chamber includes a lower wall that delimits the accumulation area in the bottom portion of the chamber. Thus, the coolant in liquid state coming from the evaporator separates into a gaseous phase and a liquid phase, the latter of which accumulates by gravity above the lower partition, inside the accumulation area.
The heat exchanger is called an internal or exchanger or an internal heat exchanger because it is configured so that the coolant circulating inside the “high-pressure” branch can transfer heat to the coolant circulating inside the “low-pressure” branch. It is therefore understood that the exchange occurs between the same fluid circulating in different locations of the air conditioning loop, without an exchange with air, for example.
Document JP10019421 (NIPPON SOKEN; DENSO CORP) proposes combining the internal heat exchanger and the accumulator in a combined device. In general, the latter includes said chamber, which is equipped with an opening closed by a lid. The chamber houses the internal heat exchanger, which hangs over the accumulation area for the coolant in the liquid state in the position of use of the combined device on the air conditioning loop.
The high-pressure coolant coming from the gas cooler penetrates the interior of the combined device by means of a “high-pressure” inlet, provided through the chamber in order to circulate inside the internal heat exchanger and finally be discharged from the combined device by means of a “high-pressure” outlet also provided through the chamber.
The low-pressure coolant coming from the evaporator penetrates the inside of the combined device by means of a “low-pressure” inlet, also provided through the chamber. The low-pressure coolant in the liquid state tends to accumulate by gravity above the lower wall of the chamber, while the low-pressure coolant in the gaseous state tends to concentrate in an upper area of the chamber. The latter houses a bent U-shaped conduit, of which a first end is arranged in the upper portion of the chamber in order to admit, into the conduit, the low-pressure coolant in the gaseous state, and carry it to a second end of the conduit communicating with the internal heat exchanger. Inside the latter, the high-pressure coolant transfers heat to the low-pressure coolant. The low-pressure coolant in the gaseous state is discharged from the internal heat exchanger and from the combined device through a “low-pressure” outlet, also provided through a wall of the chamber.
However, this combined device according to the prior art has major disadvantages.
Indeed, said document JP 10019421 does not take into account the integration of such a combined device in an engine compartment of a vehicle. It appears to be restrictive, with regard to the arrangement of the air conditioning loop, for the “high-pressure” and “low-pressure” coolant inlets and outlets to all be provided on the same side, i.e. through the top portion of the chamber. Moreover, the integration of the device in the vehicle requires technical solutions to be found so as to minimize the space used by the component in question.
The objective of this invention is therefore to solve the above-mentioned disadvantages primarily by inventively arranging the heat exchanger in the chamber of the accumulator. To do this, the heat exchanger is off-centered with respect to the chamber so as to minimize the external dimensions of the combined device. This arrangement enables a discharge chamber to be created laterally with respect to the exchanger without the obligation of increasing the diameter of the chamber, or extending the chamber in order to create a discharge chamber under the heat exchanger.
The invention therefore relates to a combined device including a chamber housing at least one heat exchanger and an accumulation area, in which said chamber extends according to a primary central axis and said heat exchanger extends according to a secondary central axis, characterized in that the primary central axis is offset with respect to the secondary central axis.
According to a first feature of the invention, the offset between the primary central axis and the secondary central axis is between one and twenty-five millimeters.
According to a second feature of the invention, the chamber and the heat exchanger have a cylindrical shape.
According to another feature of the invention, the heat exchanger includes at least one first flat tube wound on itself about the secondary central axis.
According to another feature of the invention, the first flat tube includes a plurality of channels.
According to another feature of the invention, the heat exchanger includes an intake chamber that extends to the center of the first flat tube wound on itself.
Advantageously, the combined device includes a discharge chamber located at least partially around the heat exchanger, wherein said discharge chamber is delimited by an external wall of the heat exchanger and by an internal wall of the chamber.
Also advantageously, the heat exchanger includes a first circulation path delimited by the plurality of channels of the first flat tube, wherein said first circulation path is in communication via a first end of the flat tube with the intake chamber and in communication with the discharge chamber by means of a second end of the first flat tube.
According to an advantageous feature of the invention, the first circulation path is delimited by a second flat tube wound with the first flat tube.
The heat exchanger includes a second circulation path delimited by a plurality of channels of a third flat tube wound with the first flat tube.
According to another feature of the invention, the second circulation path is, on the one hand, in communication with the first channel placed at the periphery of the heat exchanger and, on the other hand, in communication with a second channel of which the axis is aligned with the secondary central axis.
In addition, the first flat tube and the second flat tube, the third flat tube, the first channel and the second channel form a unitary assembly.
Moreover, the chamber is closed by an upper partition and a lower partition and the accumulation area comprises a lower wall arranged at the border between the heat exchanger and said accumulation area.
The device according to the invention comprises a first conduit that passes through the upper partition and leads into a separation area located in the chamber and above the accumulation area.
Finally, the combined device includes a second conduit that passes through the lower partition and leads into the discharge chamber.
The invention also relates to an air conditioning loop in which a combined device is incorporated, including at least one of the features indicated above.
A very first advantage of the invention lies in the fact that it is possible to preserve a component with low external bulk without increasing the internal head losses, in particular on the first circulation path. This enables the component to be more easily integrated according to the invention in an engine compartment in which the space is increasingly reduced.
Other features, details and advantages of the invention will become clearer in view of the following description provided for illustrative purposes, in association with the drawings, in which:
The above-mentioned figures will be used to describe an implementation of the invention, and can also help to define it better, as the case may be.
The chamber 2 extends according to a primary central axis A in a longitudinal direction. The chamber 2 has a cylindrical cross-section, but can also be parallelepiped (square, rectangular, etc.). The length of the chamber 2 measured in the direction of the primary central axis A is greater than the external diameter measured perpendicularly to the primary central axis A.
The combined device 1 also comprises a “high-pressure” inlet 5 through which a coolant 16 combing from a gas cooler is admitted into the combined device 1. This “high-pressure” inlet 5 consists of a first tubular channel 12 that passes through the lower partition 4 in order to be connected to a heat exchanger 9. The combined device 1 also comprises a “high-pressure” outlet 6 through which the high-pressure coolant is discharged from the combined device 1 to the expansion member. This “high-pressure” outlet 6 is in the form of a second tubular channel 13, which starts at the level of the heat exchanger 9 in order to pass through the internal volume of the chamber 2 and lead through the upper partition 3.
The combined device 1 also comprises a “low-pressure” inlet 7 through which the coolant coming from the evaporator is admitted into the combined device 1. The “low-pressure” inlet 7 is in the form of a first conduit 14 that passes through the upper partition 3. The combined device 1 finally comprises a “low-pressure” outlet 8 through which the low-pressure coolant is discharged from the combined device 1 to the compressor. This “low-pressure” outlet 8 is, in this case, also in the form of a second tubular conduit 15 that passes through the lower partition 4.
The combined device 1 includes the chamber 2, which is sealed with respect to the outside, which houses the heat exchanger 9, a separation area 10 between the gaseous phase 16a and the liquid phase 16b of the coolant leaving the evaporator, as well as an accumulation area 11 for the coolant in the liquid state coming from the evaporator, or more specifically coming from the separation area 10.
Said separation area 10 preferably has a cyclone structure in the sense that the first conduit 14 is offset with respect to the primary central axis A of the chamber 2 of the combined device 1 in order to enable tangential intake of the coolant coming from the evaporator inside said separation area 10. The tangential intake is implemented by means of a hole 17 provided through the cylindrical wall of the first conduit 14. These arrangements are intended to promote the mutual separation of said gaseous phase 16a and said liquid phase 16b. An end of the first conduit 14 located inside the internal volume of the chamber 2 is closed off by a plate 18. This plate extends perpendicularly to the primary central axis A of the chamber 2. A small clearance is maintained between the periphery of said plate 18 and the internal wall 19 of the chamber 2 so as to allow the liquid phase 16b of the coolant 16 to descend by gravity toward the accumulation area 11. The accumulation area 11 begins below the plate 18.
This accumulation area is delimited by a lower wall 20, against which the coolant in the liquid state coming from the evaporator accumulates by gravity. As the “low-pressure” inlet 7 is, in the use position of the combined device 1 on the air conditioning loop and/or in the operating position of the combined device 1 alone, placed above the lower wall 20, the coolant 16 in the liquid state naturally falls by gravity from the “low-pressure” inlet 7 toward the lower wall 20 so as to finally rest against the latter. The lower wall 20 is tightly mounted against the internal wall 19 of the chamber 2.
The accumulation area 11 is passed through by the second channel 13, but it is also passed through by an intermediate conduit 21, of which a first end 21a leads into the separation area 10, several millimeters above a plane defined by the plate 19. This arrangement makes it possible to ensure that the liquid phase 16b of the coolant does not return to the intermediate conduit 21 so that only the gaseous phase 16a of the coolant 16 can penetrate it. The intermediate conduit 21 passes through the lower wall 20 and has a second end 21b that is in communication with the heat exchanger 9. In a first configuration shown in
It is noted that the coolant 16 in the gaseous state descends toward the internal exchanger 9 while the coolant carried in the second channel 6 rises in the direction of the upper partition 3. The circulation in this portion of the combined device is said to be “counter-current”.
The lower wall 20 is preferably perpendicular to the primary central axis A of the chamber 2 of the combined device 1.
The separation area 10 is contiguous to said upper partition 3, by being positioned directly below the latter. Thus the accumulation area 11 is placed between the separation area 10 and the lower wall 20, and the plate 18 is inserted between the separation area 10 and the accumulation area 11.
The lower wall 20, which delimits, in the bottom portion, the accumulation area 11, is arranged above the heat exchanger 9. It is noted that the accumulation area 11 is arranged above the heat exchanger 9 according to the gravity axis.
The cross-section of the chamber 2 and the cross-second of the heat exchanger 9 are both cylindrical, thereby providing perfect shape cooperation.
The accumulation area 11 overhanging or placed above the heat exchanger 9 is higher than the heat exchanger 9, according to the primary central axis A of the chamber 2.
The heat exchanger 9 consists of a first flat tube 22 wound on itself, preferably about a secondary central axis B of the heat exchanger, in which said secondary central axis B is distinct from, i.e. non-coaxial to, the primary central axis A of the chamber 2 of the combined device 1. It is noted that this offset d, formed by the distance that separates the primary central axis A from the secondary central axis B, enables an area of the lower partition 4 to be freed, into which it is then easier to lead the second channel 15 without increasing the external dimensions of the chamber 2, and therefore of the combined device as a whole. It is noted that the primary central axis A and the secondary central axis B are parallel.
The first flat tube 22 houses a plurality of channels 23, also called micro-channels, for the passage of the low-pressure coolant. This plurality of channels consists of a first circulation path for the low-pressure coolant. This first circulation path is in communication, on the one hand, with an intake chamber 24 and, on the other hand, with a discharge chamber 25. The intake chamber 24 is delimited by the end 21b of the intermediate conduit 21, by the first turn of the first flat tube 22 wound on itself and by the lower partition 4.
The discharge chamber 25 is delimited by a peripheral turn of the winding of the first flat tube 22 and/or a third flat tube 27 (which will be described below in greater detail), thus defining the external wall of the heat exchanger 9, by the lower wall 20, by the lower partition 4 and finally by the internal wall 19 of the chamber 2 plumb over the heat exchanger 9. The consequence of the offset d between the primary central axis A and the secondary central axis is the ovoid shape of the cross-section of the discharge chamber.
The first circulation path includes a second flat tube 26 equipped with a plurality of channels 23. This second flat tube 26 is wound with the first flat tube 22 and together they form the first circulation path for the “low-pressure” coolant 16.
The heat exchanger 9 also includes a third flat tube of which the plurality of channels 23 delimits a second circulation path, wherein the latter is adopted by the “high-pressure” coolant. This third flat tube 27 is, on the one hand, in communication with the first channel 12 placed at the periphery of the heat exchanger and, on the other hand, in communication with the second channel of which the axis is aligned or merges with the secondary central axis B of the heat exchanger 9. The first channel 12 is then tightly connected (for example, welded, brazed, etc.) to the end of the third flat tube 27 and the plurality of channels 23 communicate fluidly with the inside of the first channel 12. The same is true of the other end of the third flat tube 27, which communicates with the second channel 13.
If the heat exchanger 9 does not include a second flat tube 26, it then consists of a first flat tube 22 and a third flat tube 27 jointly wound so as to form the first circulation path and the second circulation path, respectively.
In an alternative in which the first circulation path is equipped with a first and a second flat tube 22, 26, the third flat tube 27 is then inserted or sandwiched between the first and second flat tubes.
In these cases, the three flat tubes (first, third and second) are wound about the secondary central axis B of the heat exchanger 9 so that the respective turns formed by said tubes are interleaved one in the other.
An intermediate subassembly consists of the first flat tube 22 and the second flat tube 26, the third flat tube 27, the first channel 12 and the second channel 13 so as to form a unitary assembly. This assembly is constructed insofar as the aforementioned elements are unremovably connected without destroying the unitary assembly. It advantageously involves a solid and tight connection (ensured, for example, by brazing, welding, etc.), which enables all of said elements to be connected to one another.
The intersection between the interrupted line E-E and the interrupted line F-F shows the secondary central axis B of the heat exchanger 9. The offset d is the distance that separates the primary central axis A of the chamber 2 and the secondary central axis B of the heat exchanger 9, wherein said offset is a minimum value of one millimeter below which the gain in space lateral to the heat exchanger 9 becomes marginal. The maximum value of the offset d is twenty-five millimeters because it is the maximum value to maintain a satisfactory compromise between the external diameter of the heat exchanger and the external diameter of the chamber 2.
Between these two values, the invention frees a space lateral to the heat exchanger 9, and this space then constitutes the discharge chamber 25. It is noted that the second conduit 15 can then be placed more easily without requiring an increase in the diameter of the chamber 2, with a constant diameter of the heat exchanger 9, diameter of the chamber 2 and diameter of the second conduit 15.
The third flat tube 27 is connected by one end to the first channel 12 located at the periphery of the heat exchanger 9, while the other end of the third flat tube 27 is connected to the second channel 13 of which the axis merges with the secondary central axis B of the heat exchanger 9.
The first flat tube 22 and the second flat tube 26 collect the coolant in the gaseous state at “low pressure” in the intake chamber via the end of the flat tubes. The coolant at “low pressure” goes into the first and second flat tubes 22, 26 at a counter-current to the circulation of the coolant at “high pressure”, which goes into the third flat tube 27. The “low-pressure” fluid leaves through the ends of the first and second flat tubes 22 and 26 so as to spread into the discharge chamber 26 and leave the combined device 1 via the second conduit 15.
The provisions described above are such that the combined device 1 is capable of being fluidly connected to the air conditioning loop by means of upper 3 and lower 4 partitions. Therefore, the connections between the combined device 1 and, on the one hand, the compressor and, on the other hand, the gas cooler, are produced by means of conduits connected over the lower partition 4, while the connections between the combined device 1 and, on the one hand, the evaporator and, on the other hand, the expansion member, are produced by means of conduits connected over the upper partition 3. Such arrangements facilitate the integration of the combined device 1 on the air conditioning loop and consequently the integration thereof in the engine compartment of the motor vehicle.
The terms “above”, “below”, “overhanging”, “lower” and “upper” should be understood according to the position of use of the combined device 1. This position of use can easily be determined by the installation of the combined device 1 according to the invention in the air conditioning loop of the vehicle. This position of use can nevertheless also easily be determined with the combined device 1 alone, i.e. independently of its installation in the air conditioning loop, insofar as its operation appears to be realistic.
| Number | Date | Country | Kind |
|---|---|---|---|
| FR08/07422 | Dec 2008 | FR | national |
