Patent Application
20180306517
The disclosure relates to a combined heat exchanger, and more particularly a combined heat exchanger for a motor vehicle, wherein the heat exchanger comprises an oil cooler and a condenser. Although the combined heat exchanger is described within the context of a motor vehicle, it will be appreciated that the combined heat exchanger may be used in other applications without departing from the scope of the disclosure.
In a heat exchanger of this type, the oil cooler and the condenser are cooled with the same airstream. In the oil cooler, a plurality of oil cooler tubes with a plurality of oil cooler ducts are arranged in stacks, wherein the air for cooling the oil flowing in the oil cooler tubes flows between the individual oil cooler tubes. The condenser may be similarly constructed from a plurality of condenser tubes with a plurality of condenser ducts suitable for being traversed by a cooling fluid and the condenser is spatially separated from the oil cooler.
Both the temperature and also the viscosity of the fluids to be cooled differ greatly. In order to make possible an optimum cooling of the two fluids with the same airstream, the flow velocity of the two fluids and the cross section and the position of the oil cooler ducts and of the condenser ducts can be adapted for example.
From the publication U.S. Pat. No. 6,394,176 B1 it is known for example that a hydraulic diameter DHA of the two oil cooler ducts and a hydraulic diameter DHB of the condenser ducts can be adapted to one another in order to achieve an optimum cooling of the two fluids in the combined heat exchanger. There, a range between 0.8 mm2 and 3 mm2 for the product of the hydraulic diameters DHA and DHB is stated. The hydraulic diameter of a rectangular duct in this case is given as a quotient of four times the cross-sectional area and of the circumference of the duct.
However, in the case of ducts which are longer than, e.g., 600 mm, or significantly deviate from a rectangle in their cross section, optimum heat exchange between the two fluids and the airstream can no longer be achieved in ranges according to conventional approaches.
It is therefore the object of the disclosure to provide a combined heat exchanger of the aforementioned type with an improved construct of an oil cooler including at least one oil cooler duct having a hydraulic diameter DÖK and a condenser including at least one condenser duct having a hydraulic diameter DKD, where a range for the product of the hydraulic diameters DÖK and DKD achieves an optimum heat exchange between the two fluids and the airstream, even when the respective ducts are longer than a predefined distance, e.g., greater than 600 mm, and/or greatly deviate from a rectangle in their cross section.
According to the disclosure, this object is solved through the subject of the independent claim(s). Advantageous embodiments are subject of the dependent claims.
The present disclosure is based on the general idea of a combined heat exchanger including tubes and/or ducts possessing a product of a hydraulic diameter DÖK and of a hydraulic diameter DKD that is greater than 3 mm2 and smaller than 20 mm2, and tubes and/or ducts possessing a product of the hydraulic diameter DÖK and of the hydraulic diameter DKD that is greater than 0.1 mm2 and smaller than 0.8 mm2, which can be expressed by the formula:
3 mm2<DÖK×DKD<20 mm2 or 0.1 mm2<DÖK×DKD<0.8 mm2.
The hydraulic diameter DÖK may describe an oil cooler duct in an oil cooler tube of an oil cooler and the hydraulic diameter DKD may describe a condenser duct in a condenser tube of a condenser in the combined heat exchanger. In the case of a rectangular cross section of the oil cooler duct and/or of the condenser duct, the hydraulic diameter can be calculated as a quotient of four times the cross-sectional area and of the circumference of the respective duct.
In order to achieve an optimum heat exchange between the fluids in the oil cooler duct and in the condenser ducts and a cooling medium (e.g., an airstream or a gas flow) in the case of longer air cooler ducts and condenser ducts, the range between 3 mm2 and 20 mm2 can be selected for the product of the hydraulic diameters DÖK and DKD. In this range, a larger cross section of the oil cooler ducts and/or of the condenser duct than with the conventional oil cooler ducts and/or condenser ducts can be selected so that the flow velocity and the pressure of the fluids in the oil cooler and/or in the condenser is retained at an optimum level even with the longer oil cooler ducts and/or with the longer condenser ducts.
In order to achieve an optimum heat exchange between the two fluids in the oil cooler ducts and in the condenser ducts and the cooling medium with the oil cooler ducts and/or with the condenser ducts having cross sections greatly deviating from a rectangle, the range between 0.1 mm2 and 0.8 mm2 can be selected for the product of the hydraulic diameters DÖK and DKD. In this range, cross sections for example in the form of an equilateral, of a triangle or of a rectangle that is greatly expanded in a dimension can be selected for the oil cooler ducts or for the condenser ducts.
In an advantageous further development of the solution according to the invention it is provided that the oil cooler tube and/or the condenser tube are designed as a flat tube, wherein the flat tube has an almost rectangular tube cross section. In the flat tube, the heat exchange between the fluids and the airstream cooling the flat tube takes place on a larger area and can thus be optimised.
Advantageously it is provided that the flat tube has a width between 12 mm and 22 mm, preferably between 15.5 mm and 20.5 mm. It is also provided that the flat tube has a height between 1 mm and 6 mm, preferably between 1.5 mm and 5 mm. By way of such a configuration the flat tubes can be easily stacked to form an oil cooler or into a condenser and, during a repair, be easily replaced.
Advantageously it is provided that the oil cooler tube has a height between 3 mm and 6 mm, preferably between 4 mm and 5 mm. The condenser tube has a height between 1 mm and 3 mm, preferably between 1 mm and 2 mm. By way of such a configuration the oil cooler tube and the condenser tube can be easily stacked to form an oil cooler or a condenser and, during a repair, be easily replaced.
In a further development of the oil cooler tube it is advantageously provided that the oil cooler tube comprises at least two oil cooler ducts, preferably five oil cooler ducts. Furthermore, the condenser tube comprises at least two condenser ducts, preferably ten to eighteen condenser ducts, which are arranged next to one another. The oil cooler ducts as well as the condenser ducts are arranged next to one another and are each separated from one another by a separating wall. The separating wall can be produced from the same material as the oil cooler tube and as the condenser tube and integrally formed on the oil cooler tube and on the condenser tube. Alternatively, the separating wall may be a separate insert arranged in the oil cooler tube and/or the condenser tube to define at least two separate ducts.
Through the individual ducts, the fluids are divided into a plurality of individual fluid flows, so that a better heat exchange between the fluids flowing in the individual ducts and the cooling medium cooling the oil cooling tube and condenser tube is achieved. In particular, the heat exchange between the fluids and the airstream cooling the oil cooling tube and in the condenser tube does not only take place through side wall forming the oil cooling tube or the condenser tube but also between the individual fluid flows via the separating walls separating the individual ducts. The fluid in the oil cooler tubes may be an oil, for example engine oil or transmission oil. The fluid in the condenser tubes may be a cooling fluid, for example a refrigerant of an air-conditioning system.
In a preferred embodiment, the oil cooler tube comprises five ducts arranged next to one another, for example in a width direction of the oil cooler tube. With five ducts arranged next to one another, an optimum number of fluid flows in the oil cooler tube is achieved and the pressure and the flow velocity of the fluid nevertheless retained at an optimum level in the individual fluid ducts. In a preferred embodiment the condenser tube comprises ten to eighteen ducts arranged next to one another, for example in a width direction of the condenser tube.
Advantageously, the respective oil cooler ducts and/or the condenser ducts can have a substantially rectangular duct cross section. In this way, the individual ducts can be arranged next to one another in a space-saving manner and because of this the dimensions of the oil cooler and/or of the condenser reduced as well.
In a further development of the oil cooler ducts it is provided that the oil cooler duct has a width between 2 mm and 3.5 mm, preferably between 2.5 mm and 3 mm. Advantageously it is also provided that the oil cooler duct has a height between 3 mm and 4.5 mm, preferably between 3.5 mm and 4 mm. In a preferred embodiment, the individual oil cooler ducts have an almost rectangular cross section and are arranged in the oil cooler tube next to one another.
In a further development of the condenser ducts it is provided that the condenser duct has a height between 1 mm and 3 mm, preferably between 1.5 mm and 1.8 mm. In a preferred embodiment, the individual condenser ducts have an almost rectangular cross section and are arranged in the condenser tube next to one another.
Advantageously it is provided that the oil cooler tube and/or the condenser tube are produced by an extrusion method. Accordingly, the oil cooler tube or the condenser tube can be cost-effectively produced in the form of a flat tube with a plurality of ducts as well as in any other form.
Although the combined heat exchanger disclosed herein is described within the context of an oil cooler and a condenser, it will be appreciated that the combined heat exchanger may be adapted for cooling other fluids and/or integrated into other circuits without departing from the scope of the disclosure. For example, the oil cooler may be configured as a coolant cooler or an exhaust gas cooler, and/or the condenser may be configured as an evaporator.
Further important features and advantages of the invention are obtained from the subclaims, from the drawings and from the associated figure description by way of the drawings.
It is to be understood that the features mentioned above and still to be explained in the following cannot only be used in the respective combination stated but also in other combinations or by themselves without leaving the scope of the present disclosure.
While the claims are not limited to a specific illustration, an appreciation of the various aspects is best gained through a discussion of various examples thereof. Preferred exemplary illustrations of aspects of the disclosure are shown in the drawings and are explained in more detail in the following description, wherein same reference characters relate to same or similar or functionally same components. Although the drawings represent illustrations, the drawings are not necessarily to scale and certain features may be exaggerated to better illustrate and explain an innovative aspect of an example. Further, the exemplary illustrations described herein are not intended to be exhaustive or otherwise limiting or restricted to the precise form and configuration shown in the drawings and disclosed in the following detailed description.
Exemplary illustrates are described in detail by referring to the drawings, in each case schematically, as follows:
Referring now to the drawings, exemplary illustrates are shown in detail. The various features of the exemplary approaches illustrated and described with reference to any one of the figures may be combined with features illustrated in one or more other figures, as it will be understood that alternative illustrations that may not be explicitly illustrated or described may be able to be produced. The representative illustrates relate to a combined heat exchanger for cooling fluids used in an automotive vehicle. The combined heat exchanger may include a first section and a second section for cooling different fluids. The first section may include one or more first tubes for conveying a first fluid, and the second section may include one or more second tubes for conveying a second fluid, wherein the first tube(s) and the second tube(s) are arranged to be traversed by an external flow of a cooling medium, such as air and/or exhaust gas. The first tube(s) has a first hydraulic diameter and the second tube(s) has a second hydraulic diameter, wherein a product of the first hydraulic diameter and the second hydraulic diameter defines one of a first value in a range of greater than 3 mm2 to 20 mm2 and a second value in a range of from 0.1 mm2 to 0.8 mm2. According to an example, the first tube(s) may have one or more first ducts defining the first hydraulic diameter and the second tube(s) may have one or more second ducts defining the second hydraulic diameter. Pursuant to a particular implementation, the first section may be an oil cooler and the second section may be a condenser.
In the oil cooler 2, the oil cooler tubes 4 are arranged in stacks (e.g., along a stacking direction), wherein the air for cooling the oil flowing in the oil cooler tubes 4 flows between the individual oil cooler tubes 4. The condenser is similarly constructed from a plurality of condenser tubes 5 and is spatially separated from the oil cooler 2. Accordingly, the oil cooler 2 comprises an oil cooler inlet 6 and an oil cooler outlet 7, which make possible an oil circuit separated from the condenser 3. The condenser 3 comprises a condenser inlet 8 and a condenser outlet 9.
The product of the hydraulic diameter DÖK and DKD in this case is in the range of 0.8 mm2 and 20 mm2, so that even with a length (e.g., in a longitudinal direction) of the flat tube 10 of more than 625 mm, and preferably more than 650 mm, the flow velocity and the pressure of the fluids in the oil cooler and in the condenser are retained at an optimum level.
The product of the hydraulic diameter DÖK and DKD may have a first value in a range of greater than 3 mm2 and smaller than 20 mm2. The first value of the product DÖK×DKD may provide improvements with respect to flow velocity in tubes and/or ducts having a length greater than conventional thresholds, for example greater than 600 mm.
The product of the hydraulic diameter DÖK and DKD may have a second value in a range of 0.1 mm2 and 0.8 mm2. The second value of the product DÖK×DKD may provide improvements with respect flow velocity in tubes and/or ducts having non-rectangular cross sections, including but not limited to cross sections that are round, circular, oval, triangular, equilateral, and angled.
It will be appreciated that the aforementioned heat exchanger 1 and/or oil cooler 2 and/or condenser 3 may be modified to have some components removed, or may have additional components added, all of which are deemed to be within the spirit of the present disclosure. Even though the present disclosure has been described in detail with reference to specific embodiments, it will be appreciated that the various modifications and changes can be made to these embodiments without departing from the scope of the present disclosure as set forth in the claims. The specification and the drawings are to be regarded as an illustrative thought instead of merely restrictive thought.
All terms used in the claims are intended to be given their broadest reasonable constructions and their ordinary meanings as understood by those knowledgeable in the technologies described herein unless an explicit indication to the contrary in made herein. In particular, use of the singular articles such as “a,” “the,” “said,” etc. should be read to recite one or more of the indicated elements unless a claim recites an explicit limitation to the contrary.
