Patent Application
20100155028
The present invention falls into the field of air-conditioning loops collaborating with a motor vehicle heating, ventilation, and/or air-conditioning unit. Its subject is a combined device comprising an internal heat exchanger and an accumulator forming part of such a loop. A further subject of the invention is an air-conditioning loop comprising such a combined device.
A motor vehicle is commonly equipped with a heating, ventilation and/or air-conditioning unit to regulate the aerothermal parameters of the air contained inside the vehicle interior. A unit such as this collaborates with an air-conditioning loop to cool an air flow before the latter is delivered to the vehicle interior. Said loop comprises a plurality of elements through which a refrigerant fluid, such as a supercritical fluid, notably carbon dioxide known by the reference R744, circulates in succession. These elements comprise at least a compressor, a gas cooler, an internal heat exchanger, an expansion member, an evaporator and an accumulator.
The refrigerant fluid flows from the compressor to the gas cooler, then through a “high-pressure” leg of the internal heat exchanger, then to the expansion member and thereafter through the evaporator and on to the accumulator and finally through a “low-pressure” leg of the internal heat exchanger, before returning to the compressor.
The compressor is intended to receive the refrigerant fluid in the gaseous state and to compress it to raise it to a high pressure. The gas cooler is able to cool the compressed refrigerant fluid, at a relatively constant pressure, giving up heat to its surroundings. The expansion member is able to lower the pressure of the refrigerant fluid leaving the gas cooler, converting it at least partially into the liquid state. The evaporator for its part is able to convert the refrigerant fluid in the liquid state coming from the expansion member into a gaseous state at a relatively constant pressure, by drawing heat from said air flow passing through the evaporator. The vaporized refrigerant fluid is then drawn up by the compressor. These arrangements are such that the refrigerant fluid is at a high pressure inside the “high-pressure” leg of the internal heat exchanger, while it is at low pressure inside the “low-pressure” leg of the internal heat exchanger.
The accumulator performs the function of separating a gaseous phase of the refrigerant fluid from a liquid phase thereof. To do this, the accumulator comprises a separation zone devoted to this function. The accumulator also plays a part in storing a circulating charge of refrigerant fluid dependent on the conditions of use of the air-conditioning loop. To do that, the accumulator comprises an accumulation zone in which the refrigerant fluid in the liquid state that this accumulator collects from the evaporator accumulates. In general terms, the accumulator is made up of a chamber housing the separation zone and the accumulation zone, the chamber comprising a lower wall which delimits the accumulation zone at the lower part of the chamber. Thus, the refrigerant fluid in the liquid state coming from the evaporator separates into a gaseous phase and into a liquid phase, the latter accumulating under gravity above the lower wall, inside the accumulation zone.
The internal heat exchanger is configured such that the refrigerant fluid circulating through the “high-pressure” leg can give up heat to the refrigerant fluid circulating in the “low-pressure” leg.
Document JP 10019421 (NIPPON SOKEN; DENSO CORP) proposes associating the internal heat exchanger and the accumulator in the form of a combined device. In general terms, the latter comprises said chamber which is provided with an opening closed off by a cover. The chamber houses the internal heat exchanger which sits vertically above the accumulation zone in which the refrigerant fluid in the liquid state accumulates, the heat exchanger being interposed between the separation zone and the accumulation zone when the combined device is in the position of use on the air-conditioning loop.
The high-pressure refrigerant fluid from the gas cooler enters the combined device by way of a “high-pressure” inlet created through the cover to circulate inside the internal heat exchanger and finally be removed from the combined device by way of a “high-pressure” outlet likewise created through the cover.
The low-pressure refrigerant fluid from the evaporator enters the combined device by way of a “low-pressure” inlet once again formed through the cover. The low-pressure refrigerant fluid in the liquid state tends to accumulate under gravity on top of the lower wall of the chamber while the low-pressure refrigerant fluid in the gaseous state tends to be concentrated in an upper zone of the chamber. The latter houses a bent pipe arranged in a U shape, a first end being positioned in the upper part of the chamber to admit the low-pressure refrigerant fluid in the gaseous state into the pipe and convey it as far as a second end of the pipe that communicates with the internal heat exchanger. Within the latter, the high-pressure refrigerant fluid gives up heat to the low-pressure refrigerant fluid. The low-pressure refrigerant fluid in the gaseous state is removed from the internal heat exchanger and from the combined device through a “low-pressure” outlet once again created through the cover.
A combined device such as this has disadvantages in terms of excessive structural complexity that is worth simplifying.
More specifically, a combined device such as this is made up of a considerable number of disparate components, leading to manufacturing costs that need to be reduced.
Finally, the device as described in document JP 10019421 does not take into consideration the fact that a combined device such as this is incorporated into the engine compartment of a motor vehicle. It would seem restrictive in terms of the layout of the air-conditioning loop, for the “high-pressure” and “low-pressure” inlets and outlets for the refrigerant fluid all to be created on the same side, that is to say through the cover of the chamber.
A first object of the present invention is to propose a combined device comprising a chamber housing an internal heat exchanger and an accumulation zone for a refrigerant fluid in the liquid state flowing through the combined device, the structural arrangement of the components that make up said device being as simple as possible, and the number of such components being as low as possible.
A second object of the present invention is to propose an air-conditioning loop comprising such a combined device, the layout thereof making it easier to incorporate it into the air-conditioning loop in certain configurations of the latter. The present invention takes into account the inlets or outlets for refrigerant fluid which are positioned at each end of the combined device according to the invention. Specifically, the circuit followed by ducts conveying the refrigerant fluid in the engine compartment is dictated by the space available therein. Connecting two ducts per end of the combined device is of considerable advantage over a combined device according to the prior art in which all four ducts are positioned together at one and the same end.
The device of the present invention is a combined device comprising a chamber housing at least one internal heat exchanger and an accumulation zone. Said accumulation zone is delimited by at least one lower wall. The lower wall is above the internal heat exchanger.
For preference, the chamber comprises an upper separator and a lower separator opposite one another, the upper separator being equipped with a “low-pressure” inlet and with a “high-pressure” outlet, while the lower separator is equipped with a “high-pressure” inlet and with a “low-pressure” outlet. The “low-pressure” inlet is connected to the “low-pressure” outlet by way of a “low-pressure” flow path which passes through the combined device, the “high-pressure” inlet being connected to the “high-pressure” outlet by way of a “high-pressure” flow path that passes through the combined device.
The upper separator is preferably arranged as an upper cover for closing off an upper opening that the chamber comprises, while the lower separator is arranged as a lower cover for closing off a lower opening that the chamber likewise comprises.
The upper cover is advantageously equipped with said “low-pressure” inlet and with said “high-pressure” outlet, while the lower cover is equipped with said “high-pressure” inlet and with said “low-pressure” outlet.
According to a first alternative form of the embodiment, the chamber comprises a tube housing a dividing separator separating said accumulation zone from said internal heat exchanger, the dividing separator constituting said lower wall.
According to a second alternative form of the embodiment, the chamber comprises an upper receptacle and a lower receptacle joined together top to tail by way of their respective end walls, which together constitute said lower wall.
For preference, the chamber also houses a separation zone which adjoins the upper cover.
The accumulation zone is preferably interposed between the separation zone and the lower wall.
A plate is preferably interposed between the separation zone and the accumulation zone.
A space is advantageously created between an edge of the plate and at least one side wall delimiting the accumulation zone.
The “high-pressure” inlet and the “low-pressure” outlet are preferably diametrically opposite one another with respect to a longitudinally extending axis Δ of the combined device, this axis being the longitudinal axis of the chamber.
For preference, the “high-pressure” inlet, the “low-pressure” outlet, the “low-pressure” inlet and the “high-pressure” outlet are contained in one and the same overall plane P of extension of the combined device.
The internal heat exchanger preferably comprises at least one flat tube wound up on itself.
An air-conditioning loop of the present invention is chiefly recognizable in that said loop comprises such a combined device.
When the combined device is in the position of use on the air-conditioning loop, the accumulation zone lies advantageously above the internal heat exchanger.
The lower wall preferably constitutes a wall for receiving a refrigerant fluid in the liquid state coming from an evaporator that said loop comprises.
For preference, said “low-pressure” flow path makes up a “low-pressure” line BP of the air-conditioning loop, while said “high-pressure” flow path makes up a “high-pressure” line HP of the air-conditioning loop.
The present invention will be better understood, and relevant details thereof will become apparent, from studying the description which will be given of some alternative forms of embodiment in conjunction with the figures of the attached plates, in which:
In
The air-conditioning loop 1 comprises a “high-pressure” line HP which begins at the outlet from the compressor 3 and ends at the inlet to the expansion member 6, in a direction of flow 11 of the refrigerant fluid inside the air-conditioning loop 1, the gas cooler 4 and the “high-pressure” leg 9 of the internal heat exchanger 5 being interposed between these two points.
The air-conditioning loop 1 also comprises a “low-pressure” line BP which begins at the outlet from the expansion member 6 and ends at the inlet to the compressor 3, in the direction of flow 11 of the refrigerant fluid inside the air-conditioning loop 1, the evaporator 7, the accumulator 8 and the “low-pressure” leg 10 of the internal heat exchanger 5 being interposed between these two points.
The accumulator 8, situated downstream of the evaporator 7 in the direction of flow 11 of the refrigerant fluid inside the air-conditioning loop 1, allows any residue of refrigerant fluid in the liquid state leaving the evaporator 7 to be recovered. The accumulator 8 also allows a gaseous phase of the refrigerant fluid leaving the evaporator 7 to be separated from the liquid phase thereof.
The internal heat exchanger 5 and the accumulator 8 are associated into a combined device 12 together forming a one-piece assembly which jointly performs the functions of internal heat exchanger 5 and of accumulator 8. The combined nature of said device 12 allows the internal heat exchanger 5 and the accumulator 8 to be installed on the air-conditioning loop 1 simultaneously, these entities forming an integrated assembly. It also has the effect of being able to dispense with a pipe installed in the engine compartment between the outlet of the accumulator 8 and the inlet of the “low-pressure” leg 10 of the internal heat exchanger 5.
The combined device 12 comprises a “high-pressure” inlet 13 through which the refrigerant fluid from the gas cooler 4 is admitted to the combined device 12. The combined device 12 also comprises a “high-pressure” outlet 14 through which the high-pressure refrigerant fluid is removed from the combined device 12 to the expansion member 6. The “high-pressure” inlet 13 and the “high-pressure” outlet 14 are connected to one another by way of the “high-pressure” leg 9.
The combined device 12 also comprises a “low-pressure” inlet 15 through which the refrigerant fluid from the evaporator 7 is admitted into the combined device 12. The combined device 12 finally comprises a “low-pressure” outlet 16 through which the low-pressure refrigerant fluid is removed from the combined device 12 to the compressor 3. The “low-pressure” inlet 15 and the “low-pressure” outlet 16 are connected to one another notably by way of the “low-pressure” leg 10 and by a separation zone 41 and an accumulation zone 18 that the combined device 12 comprises.
In
Said separation zone 41 preferably has a cyclone type structure inasmuch as the “low-pressure” inlet 15 is offset from a longitudinally extending axis Δ of the combined device 12 to allow the refrigerant fluid from the evaporator 7 to be admitted tangentially into said separation zone 41. These arrangements are aimed at encouraging separation between the gaseous phase and the liquid phase.
The accumulation zone 18 is delimited by a lower wall 42 against which the refrigerant fluid in the liquid state from the evaporator 7 accumulates under gravity. Because, when the combined device 12 is in the position of use on the air-conditioning loop 1 and/or because when the combined device 12 alone is in its operating position, the “low-pressure” inlet 15 is positioned above the lower wall 42, the refrigerant fluid in the liquid state naturally drops under gravity from the “low-pressure” inlet 15 toward the lower wall 42 in order ultimately to come to rest against the latter.
The lower wall 42 is preferably perpendicular to the longitudinally extending axis Δ of the combined device 12. The lower wall 42 is in contact with and extended by at least one side wall 43 which runs parallel to the longitudinally extending axis Δ of the combined device 12. The side wall 43 is, for example, shaped into a cylinder of which an axis of symmetry Δ′ is coincident with the longitudinally extending axis Δ of the combined device 12. The side wall 43 delimits an upper opening 26 which is closed off by an upper cover 25. What this means is that the lower wall 42, the side wall 43 and the upper cover 25 envelop the accumulation zone 18 and the separation zone 41. In other words, the accumulation zone 18 and the separation zone 41 are jointly contained between the lower wall 42, the side wall 43 and the upper cover 25.
The separation zone 41 is contiguous with said upper cover 25, being positioned directly beneath the latter. Thus, the accumulation zone 18 is positioned between the separation zone 41 and the lower wall 42. A plate 44 is interposed between the separation zone 41 and the accumulation zone 18, a space 45 being created between an edge 46 of the plate 44 and the side wall 43 laterally delimiting the accumulation zone 18.
According to the present invention, the lower wall 42, which delimits the accumulation zone 18 at the lower part, is positioned above the internal heat exchanger 5. Contrary to what has become habitual practice in the art, the designers of the present invention have chosen to position the lower wall 42 of the accumulation zone 18, and a fortiori therefore the accumulation zone 18 itself, vertically above the internal heat exchanger 5, whereas because the refrigerant fluid in the liquid state from the evaporator 7 concentrates under gravity inside the accumulation zone 18, a combined device according to the prior art has its accumulation zone positioned below the internal heat exchanger. The terms “above”, “below”, “vertically above”, “lower” and “upper” are to be understood as referring to the combined device 12 in its position of use. This position of use can readily be assessed from how the combined device 12 according to the invention is installed in the air-conditioning loop 1 of the vehicle. This position of use may nonetheless just as easily be assessed using the combined device 12 alone, that is to say independently of its installation in the air-conditioning loop 1, provided that its operation seems realistic. In such cases, and from the ease of identification of the lower wall 42 of the accumulation zone 18, the present invention is characterized in that the internal heat exchanger 5 is positioned below said lower wall 42, which is covered with and bathed in the refrigerant fluid in the liquid state when the combined device 12 is in the position of use and/or position of operation.
Because a person skilled in the art will be able not only to identify the accumulation zone 18 of a combined device 12 but also to recognize the upper cover 25 which delimits the accumulation zone 18 and which is provided with the “low-pressure” inlet 15 for the refrigerant fluid, this same person skilled in the art will readily be able to make out the lower wall 42, which is opposite to the upper cover 25, and will note that, according to the present invention, the lower wall 42 covers the internal heat exchanger with respect to a vertical axis g symbolizing gravity, this vertical axis g being substantially parallel to said longitudinally extending axis Δ and to said axis of symmetry Δ′.
The accumulation zone 18 vertically above or placed on top of the internal heat exchanger 5 is intended to be higher than the internal heat exchanger 5 along the vertical axis g corresponding to gravity.
Advantageously, this arrangement of the accumulation zone 18 higher than the internal heat exchanger 5 is intended to be directly on top of the internal heat exchanger 5, that is to say contained in a volume delimited by the side wall 43 of the combined device 12 according to the invention and above the latter.
These arrangements are such that the internal components delimiting a “low-pressure” flow path 36 and a “high-pressure” flow path 35, particularly the pipework used to carry the refrigerant fluid, are reduced as far as possible in order to avoid excessive additional weight and additional bulk. Such pipework is also straight, thus reducing pressure drops within the combined device 12 according to the invention. More specifically, said paths 35, 36 have no bent pipes that are highly detrimental to uniform and homogeneous flow of refrigerant fluid. For example, a “high-pressure” flow path 35 passes through the combined device 12 parallel to the longitudinally extending axis Δ thereof from one end to the other (excluding the “high-pressure” leg 9 of the internal heat exchanger 5). Finally, in the commonplace scenario in which the refrigerant fluid contains oil to improve the life of the compressor 3, the fact that the accumulation zone 18 is vertically above the internal heat exchanger 5 makes it easier for the oil to be reincorporated under gravity into the “low-pressure” leg 10 of the internal heat exchanger 5.
The internal heat exchanger 5 consists for example of a flat tube wound up on itself, preferably about the longitudinally extending axis Δ of the combined device 12, the flat tube housing micropassages for the passage of high-pressure refrigerant fluid, an interstitial space being created between turns of the wound flat tube to allow the low-pressure refrigerant fluid to pass between these turns.
The internal heat exchanger 5, again for example, consists of two flat tubes wound around the longitudinally extending axis Δ of the combined device 12 in such a way that the respective turns formed by said tubes are nested with one another. In another alternative form of embodiment, the internal heat exchanger 5 comprises three flat tubes wound in a spiral, the first tube positioned between the other two tubes or sandwiched between these two tubes being the tube that forms part of the high-pressure circuit while the other two tubes have low-pressure refrigerant fluid running through them.
The upper cover 25 constitutes a preferred form of embodiment of an upper separator 19 of the chamber 17. Likewise, a lower cover 27 is a preferred form of embodiment of a lower separator 20 of the chamber 17, said lower cover 27 being fitted to a lower opening 28 of the chamber 17.
The upper separator 19 and the lower separator 20 are opposite one another, that is to say arranged at two opposite ends of the chamber 17, the latter preferably being of cylindrical and elongate shape. The upper separator 19 is equipped with the “low-pressure” inlet 15 that lets refrigerant fluid into the combined device 12 and with the “high-pressure” outlet 14 for refrigerant fluid from the combined device 12. The lower separator 20 is equipped with the “high-pressure” inlet 13 that lets refrigerant fluid into the combined device 12 and with the “low-pressure” outlet 16 for refrigerant fluid from the combined device 12.
According to the preferred form of the embodiment described hereinabove, the upper cover 25 is equipped with the “low-pressure” inlet 15 for letting refrigerant fluid into the combined device 12 and with the “high-pressure” outlet 14 for refrigerant fluid from the combined device 12, while the lower cover 27 is equipped with the “high-pressure” inlet 13 letting the refrigerant fluid into the combined device 12 and with the “low-pressure” outlet 16 for refrigerant fluid from the combined device 12.
These arrangements are such that the combined device 12 can be fluidically connected to the air-conditioning loop 1 via the upper 19 and lower 20 separators, and according to said preferred from of the embodiment, by way of the upper 25 and lower 27 covers. What this means is that the connections between the combined device 12 and, on the one hand, the compressor 3 and, on the other hand, the gas cooler 4, are made by way of pipes connected to the lower cover 27 while connections between the combined device 12 and, on the one hand, the evaporator 7 and, on the other hand, the expansion member 6, are made by way of pipes connected to the upper cover 25. Such arrangements make the combined device 12 easier to incorporate into the air-conditioning loop 1 and therefore easier to incorporate into the engine compartment of the motor vehicle.
The “high-pressure” inlet 13 and the “low-pressure” outlet 16 are created diametrically opposite each other with respect to the longitudinally extending axis Δ of the combined device 12. More particularly, the “high-pressure” inlet 13, the “low-pressure” outlet 16, the “low-pressure” inlet 15 and the “high-pressure” outlet 14 are contained in one and the same longitudinally extending plane P of the combined device 12, such as the plane of
According to a first alternative form of the embodiment illustrated in
According to a second alternative form of the embodiment illustrated in
A device 37 for recovering oil carried by the refrigerant fluid is fitted to the “low-pressure” flow path 36 to make it easier to reincorporate the oil upstream of the “low-pressure” leg 10 of the internal heat exchanger 5.
The accumulation zone 18 is also provided with a desiccant 38 to dry out the low-pressure refrigerant fluid. The accumulation zone is, for example, also provided with an oil filter 40 to hold back any impurities carried by this oil.
| Number | Date | Country | Kind |
|---|---|---|---|
| FR08/07424 | Dec 2008 | FR | national |
