Patent Application
20150129182
The present invention relates to a heat exchanger according to the features in the preamble of patent claim 1.
It is known from the state-of-the-art to use heat exchangers in particular in motor vehicles in order to cool components by a medium and/or to withdraw heat from the medium in a targeted manner. For example it is possible to cool the cooling water of an internal combustion engine of a motor vehicle in a targeted manner by a second medium, in particular air. However, it is also possible to cool exhaust gas of the motor vehicle for example in order to resupply the cooled exhaust gas itself to the internal combustion process again.
From DE 434 34 05 A1 for example a tube bundle heat exchanger is known in which a medium is introduced at one end, impacts a tube bottom and accumulates on the tube bottom and is then conducted through the heat exchanger tubes situated in the tube bottom. In accordance with the counter-flow principle, a second medium is introduced on the outside of a sheath of the heat exchanger, which second medium then flows through the heat exchanger and exits the heat exchanger again on an exit site located opposite the entry site of the second medium.
A disadvantage is that when using such a tube bundle heat exchanger as exhaust gas heat exchanger, in particular the tube bottom is at least locally exposed to high temperatures of the flowing exhaust gas.
An object of the present invention is therefore to provide a heat exchanger for a motor vehicle, whose inner components have a better resistance against high temperatures of the conducted media, while its cooling performance remains at least the same.
According to the invention, the aforementioned object is solved with a heat exchanger for a motor vehicle with the features set forth in patent claim 1.
Advantageous embodiments of the present invention are the subject matter of the dependent patent claims.
The heat exchanger according to the invention for a motor vehicle has an outer sheath and heat exchanger tubes arranged in the outer sheath and a first medium can be introduced on an endside of the sheath and a second medium can be introduced via the side surface of the sheath, and is characterized in that on an outside of the sheath an at least partially circumferential channel is formed, wherein the second medium can be introduced from a supply line into the circumferential channel and enters the interior of the sheath from the channel via openings in the sheath.
This improves cooling of a front plate or perforated plate, also known as tube bottom, which is arranged in the heat exchanger, in particular a tube bundle heat exchanger, particularly preferably an exhaust gas heat exchanger for a motor, with heat exchanger tubes traversing the front plate. A first medium is introduced into the heat exchanger at an endside thereof and is discharged again at the opposite end side. The first medium is conducted through the heat exchanger tubes. A second medium is introduced according to the counter flow or cross flow principle or parallel flow principle from a side of the sheath. According to the invention it is provided however, that the second medium is not only conducted from one side at a selective point or conducted sideways from one side through the sheath onto the heat exchanger tubes situated in the sheath of the heat exchanger, but is initially conducted via a supply line in the direction of the sheath, particularly preferably in the direction of an end of the sheath. According to the invention an at least partially radially circumferentially extending channel, in particular a completely circumferentially extending channel is formed, into which the second medium initially flows and is thereby distributed about the sheath.
In the channel itself openings are provided, wherein the second medium, which has become distributed in the channel, can enter the interior of the sheath via the openings. This ensures that the second medium does not only impact the heat exchanger tubes from one side or at a particular point but ideally enters the sheath of the heat exchanger from all sides from the outside of the sheath, in particular simultaneously and/or with approximately the same temperature, in particular flow temperature. Thus in case of a channel arranged in the region of the end of the sheath, the second medium initially flows evenly around the tube bottom, wherein the second medium is in particular a coolant, particularly preferably cooling water.
The first medium, which is introduced at a front side into the heat exchanger and thus also impacts the tube bottom, ensures a strong heating up of the tube bottom. In particular the first medium conducted through the heat exchanger is exhaust gas, which can have exhaust gas temperatures of more than 600° C., sometimes even more than 800° C. As a result of the substantially homogenous cooling of the tube bottom with the second medium, excessive heating of the tube bottom is avoided and at the same time, because such a heat exchanger is often thermally joined, in particular soldered, a one-sided deformation due to different thermal expansions is avoided. This increases the longevity and leakproofness of the heat exchanger, wherein as a result of the improved cooling of the tube bottom use of cost-intensive and temperature resistant materials can be avoided. It is thus possible to produce the heat exchanger more cost-effectively while providing an improved cooling performance.
Within the scope of the invention in particular the sheath of the heat exchanger is an outer box or an outer circumferential sheath surface. This sheath surface can itself be configured to have a round, oval or angular, in particular quadrangular, preferably rectangular or square cross section.
Further preferably within the scope of the invention, a flange engages around an outside the sheath itself, wherein the flange can be configured as tubular component or as fitting or an elbow piece, and has in particular a supply line or discharge line for the first medium. The radially circumferential channel according to the invention is formed by a radially outwardly oriented embossment of the flange, wherein the outwardly oriented embossment is in particular configured as radially outwardly oriented bulge. Thus a hollow space is generated between an inside of the bulge and an outer surface of the sheath itself. The supply line for the second medium is then in turn connected with the channel on the flange. In particular a socket and/or a recess, which forms the supply line for the channel according to the invention, is formed in the region of the bulge. As a result thereof the second medium, in particular a coolant, particularly preferably cooling water, is conducted into the channel and is distributed radially circumferentially about the outside of the sheath. The medium then enters the interior of the heat exchanger or the interior of the sheath through openings in the sheath.
In particular, the openings themselves are configured a spaced apart holes, wherein the holes in the sheath are configured so as to extend circumferentially in the region of the channel. Within the scope of the invention it is for example possible to arrange the holes radially circumferentially in the sheath at even distances to each other. In this context it is for example conceivable that the holes initially have greater distances to each other in the region of the supply line, and with increasing distance to the supply line in the direction of flow of the channel, the distances of the holes to each other decrease. For example a small number of holes is initially provided so that in the region of the supply line, in which a higher pressure and/or a higher flow velocity of the second medium is present, a relatively small portion of the second medium enters the sheath and a sufficient portion of the second medium also enters into the interior space of the sheath with increasing distance to the supply line as a result of decreasing the distance and with this increasing the number of holes, while simultaneous decreasing pressure and/or flow velocity of the second medium.
Further within the scope of the invention it is provided that the holes have different opening cross sections, wherein the opening cross sections are in particular configured to increase between spaced-apart openings in a direction from the supply line in flow direction of the channel. Thus in the region of the supply line the openings have a smaller opening cross section than the openings in flow direction distal to the supply line. The size of the opening cross section of each opening thus increases in the flow direction of the channel. This again makes it possible that the second medium has a higher pressure and/or a higher flow velocity in the region of the supply line, wherein the pressure and/or the flow velocity decreases in the flow direction of the channel so that sufficient medium is transported from the channel into the interior of the sheath, and so that a homogenous radially circumferential influx into the sheath results.
Within the scope of the invention it is further possible that the cross sectional surface of the channel is configured variable, in particular the cross sectional surface decreases from the supply line in flow direction of the channel. The decreasing cross sectional surface in turn counteracts the decreasing pressure and/or the decreasing flow velocity of the second medium in flow direction of the channel. Narrowing of the cross sectional surface enables maintaining the pressure and/or flow velocity of the second medium in flow direction of the channel approximately constant or increases it, so that a near homogeneous flow through the openings into the interior of the sheath results.
Further preferably within the scope of the invention, a guide plate is arranged in the sheath in flow direction of the first fluid downstream of the openings in the sheath, wherein the guide plate is traversed by the heat exchanger tubes and preferably has a central recess for passage of the second medium in longitudinal direction of the sheath.
The guide plate ensures that the second medium, i.e., the coolant, after entering into the sheath does not flow or stream in radial and axial direction into the interior of the sheath and thus insufficiently cools the front plate or the tube bracket. Thus the second medium first accumulates in the region of the front plate so that the second medium in particular also cools the front plate and the heat exchanger tubes at its influx region of the first medium. The second medium then flows also in axial direction in particular through a central opening or recess arranged in the guide plate into the interior of the sheath.
Further preferably a front plate is arranged upstream of the openings in the sheath in flow direction of the first fluid through the sheath, wherein the front plate is traversed by the heat exchanger tubes for passage of the first medium. Within the scope of the invention the front plate is in particular a tube bracket or a tube bottom. The latter does not have to be made of a high temperature resistant and with this cost-intensive material and can thus have a thinner wall thickness and can thus overall be produced smaller and using thinner material, which reduces the production costs by saving material. It is also possible within the scope of the invention to produce the coupling between the heat exchanger tubes and the front plate in the tube bottom, which can for example be soldered, with greater tolerances because due to the significantly improved cooling properties in the region of the front plate a thermal deformation does not adversely affect the leakproofness and with this the longevity.
For producing the heat exchanger according to the invention, at least one material joint is created in particular between the flange and the sheath, particularly preferably between the outer side of the sheath and the inside of the flange, in particular a soldered connection, particularly preferably a brazing solder joint. Within the scope of the invention it is also possible however to couple the two components flange and sheath by a welding or by an adhesive connection. In particular the sheath but also the flange are made of a metallic material for example a steel material, preferably also of a lightweight metal material. The soldering process itself provides high degrees of freedom during joining, because materials that are not weldable but can be soldered can be joined in a materially bonding and with this fluid tight manner.
In particular the channel is formed by two spaced-apart circumferential contact surfaces between the flange and the outside of the sheath, wherein the contact surfaces are in particular thermally joined in a fluid tight manner. It is thus possible to first introduce the holes in a predetermined manner, to then push the flange over the sheath and subsequent thereto produce the fluid tight thermal joint of the two components.
Further advantages features, properties and aspects of the present invention are the subject matter of the following description. Preferred embodiments are shown in the schematic figures. These are intended to facilitate understanding of the invention. It is shown in:
a and b a heat exchanger according to the invention in a perspective view and partially sectioned view,
In the Figures the same reference signs are used for same or similar components, even when a repeated description is not given for reasons of simplicity.
a shows the heat exchanger 1 according to the invention in a perspective view, having a sheath 2 and a flange 3, which is pushed onto an endside of the sheath 2. The flange 3 has an exhaust gas line 4 for supplying a flowing exhaust gas A and a supply line 5 for supplying a second medium 6. The second medium 6 enters an outer circumferential channel 7 via the supply line 5, which channel is formed by an outwardly oriented bulge 8 on the flange 3.
According to the invention the outer circumferential channel 7 has openings 9 toward the sheath 2, through which openings the respective medium 6 flows into an accumulation chamber 12 shown in
b shows the heat exchanger 1 in a perspective partial sectional view.
In
In
| Number | Date | Country | Kind |
|---|---|---|---|
| 10 2013 100 885.2 | Jan 2013 | DE | national |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/EP2013/001280 | 4/30/2013 | WO | 00 |
| Number | Date | Country | |
|---|---|---|---|
| 61641125 | May 2012 | US |
