BRIEF DESCRIPTION OF THE DRAWINGS
These and other objects and features of the present invention will become clearer from the following description of the preferred embodiments given with reference to the attached drawings, wherein:
FIG. 1 is an overview of a heat exchanger according to a first embodiment of the present invention;
FIG. 2 is an enlarged cross-sectional view of a portion X of FIG. 1;
FIG. 3 is an enlarged view of a portion Y of FIG. 1, that is, a perspective view showing a side plate (no cuts in bridge portions) according to the present invention before brazing;
FIG. 4 is a side plate (cuts in bridge portions) according to the present invention after brazing;
FIG. 5 is a view of a side plate of a conventional example;
FIGS. 6A to 6C are views showing the calculation conditions of simulation calculations, wherein FIG. 6A is a three-sided view of a side plate being calculated, FIG. 6B is a view showing the calculation conditions for calculating deflection, and FIG. 6C is a view showing the force when forcibly displacing a side plate;
FIG. 7 is a view of the results of different types of simulation calculations under the calculation conditions of FIG. 6; and
FIG. 8 is an overview of a heat exchanger according to a second embodiment of the present invention.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
First Embodiment
Below, a first embodiment of the present invention will be explained based on FIGS. 1 to 4. The first embodiment is a heat exchanger (oil cooler) 100 according to the present invention exchanging heat between the vehicle transmission oil and the atmosphere (air). FIG. 1 is an overview of an oil cooler 100 according to the first embodiment, while FIG. 2 is an enlarged cross-sectional view of a portion X of FIG. 1. FIG. 3 is an enlarged view of a portion Y of FIG. 1 showing a side plate (no cuts in bridge portions) according to the present invention before brazing. FIG. 4 is a side plate (cuts in bridge portions) according to the present invention after brazing. Note that FIG. 5 shows a side plate of a conventional example.
As shown in FIG. 1, the heat exchanger of the present invention is an oil cooler 100 air-cooling the oil of a vehicular transmission (not shown). The heat exchanger 100 of the present invention differs from the heat exchanger of the conventional type only in the side plates 7. The rest of the parts are completely the same.
The oil cooler 100 is comprised of a plurality of tubes 2 through a transmission oil passes, a plurality of fins 3 alternately stacked with the tubes and increasing the heat transfer of said oil, core plates 5a to which the two ends of said tubes 2 are connected, and side plates 7 arranged at the outsides in the stacking direction from the end fins 3a arranged further outside from the tubes arranged at the outermost sides in the stacking direction of the tubes and connected to the core plates 5a. Further, as shown in FIG. 2, the two ends of the tubes 2 and the side plates 7 are respectively inserted in tube holes and side plate holes provided in the core plates Sa and those inserted parts are brazed.
In FIG. 1, the tubes 2 are tubes in which the oil flows. The tubes 2 are formed in flat shapes so that the direction of circulation of the air (direction vertical to paper surface) matches with the longitudinal directions. A plurality of tubes are alternately arranged in parallel the vertical direction (direction of stacking of the tubes) so that their axial directions match with the horizontal direction.
Corrugated fins 3 formed in wave shapes are brazed to the flat surfaces 2a of the tubes 2 (see FIG. 2). The fins 3 increase the heat transfer area with the air and promote heat exchange of the transmission oil and air. Note that below, the substantially block shaped heat exchange portion comprised of the tubes 2 and the fins 3 will be called the “core portion 4”.
Header tanks 5 extend in directions perpendicular to the axial directions of the tubes 2 (vertical direction in the present embodiment) at the axial direction ends of the tubes 2 (the left and right ends in the present embodiment) and communicate with the plurality of tubes 2. The header tanks 5 are comprised of core plates 5a in which the tubes 2 are inserted and bonded and tank bodies 5b forming tank inside spaces with the core plates 5a.
Further, one tank 5 is provided with a pipe connection 5d to which an oil pipe (not shown) connecting an oil path provided in a transmission (not shown) and the oil cooler 100. The pipe connection 5d is an oil inlet into which oil flows from the transmission side. Further, a pipe connection 6a, part of the return pipe 6, is an oil outlet from which oil flows from the oil cooler 100 to the transmission side. However, the oil inlet and outlet may also be reversed.
As shown in FIG. 1, oil flowing in from the pipe connection 5d to the heat exchanger 100 first flows into the right side header tank 5b. Then, the oil flowing into the right side header tank 5b passes through within the tubes 2 and proceeds in the left direction while exchanging heat with the atmosphere and flows into the left side header tank 5b. The oil stored in the left side header tank 5b passes through the connection opening 6b with the return pipe 6 of the left side header tank 5b and flows into the return pipe 6. The oil passes through the return pipe 6 in the right direction and flows out from the pipe connection 6a to the transmission side.
On the other hand, the two ends of the core portion 4 (in the present embodiment, the top and bottom ends) are provided with side plates 7 extending substantially parallel with the axial direction of the tubes 2 and reinforcing the core portion 4. As shown in FIG. 3, the side plates 7 have base portions 7a having surfaces substantially parallel to the flat surfaces 2a of the tubes 2 (see FIG. 2) and extending substantially parallel to the axial directions of the tubes 2 and standing walls 7b sticking out in directions substantially perpendicular to the base portion 7a and extending substantially parallel to the axial directions of the tubes (in the present embodiment, the horizontal directions).
In the side plates 7, the standing walls 7b are provided at the two ends of the base portions 7a in the width directions of the base portions 7a, so the cross-sectional shapes of the side plates 7 are substantially U-shaped cross-sections opening at the sides opposite from the core portion 4. The reason for making the cross-sectional shapes of the side plates 7 substantially U-shaped cross-sections is to secure the rigidity of the side plates 7. Inside the cross-section of one side plate 7, a pipe 6 extends. The pipe 6 is curved and sticks out from inside the cross-section near the bridge portions 7c, 7d. Because of this, space is secured near the bridge portion 7d, so the work of cutting the bridge portion 7d becomes easy after finishing the brazing. Further, the side plates 7 contact the core portion 4 by being brazed with the fins 3a, so heat is transferred with the core portion 4.
As shown in FIGS. 1 and 3, each side plate 7 is provided with bridge portions 7c and 7d at its approximate central portion in the longitudinal direction. Note that these bridge portions may be provided at any positions in the intermediate portion in the longitudinal direction of the side plate 7. The bridge portion 7c extends at an angle with respect to the longitudinal direction of the side plate 7. FIG. 3 shows the state before brazing and at the time of brazing of the tubes 2 and fins 3 with the side plate 7. When the brazing is completed, the bridge portions 7d at the two sides are cut to form slits 7e as shown in FIG. 4. Note that by providing the bridge portions 7d at the peripheral sides (after assembly) of the side plate 7, the cutting of the bridge portions 7d becomes easy.
The reason the bridge portions 7c and 7d and the slits 7e are provided will be explained based on FIGS. 6A to 6C and FIG. 7. FIGS. 6A to 6C and FIG. 7 are views for explaining calculations for simulation of beam deformation when providing the bridge portions 7c and 7d and the bridge portion slits 7e in a side plate 7. Specifically, FIGS. 6A to 6C are views showing the calculation conditions by schematic views, wherein FIG. 6A is a three-sided view of a side plate 7 being calculated, FIG. 6B is a view showing the calculation conditions for calculating deflection, and FIG. 6C is a view showing the force when forcibly displacing a side plate 7. FIG. 7 is a view of the results of different types of simulation calculations under the calculation conditions of FIG. 6.
The side plate being calculated were made three types. The first type is the first embodiment of the present invention (with slanted bridge portions), the second type is a modification of the first embodiment (with straight bridge portions), and the third type is a conventional type with no bridge portions. These types of side plates were first, as shown in FIG. 6B, subjected to equally distributed loads of 0.065 MPa to find the deflection δ. At this time, each side plate was fixed at the two ends. The equally distributed load of 0.065 MPa was the pressure envisioned to be applied by the wires when brazing the tubes and the fins with the side plate. A small deflection δ means smaller variation in fin deformation during brazing due to the difference of fin positions, so stable brazing becomes possible.
Next, as shown in FIG. 6C, the force required for making the side plate displace by 0.2 mm in the longitudinal direction (below referred to as the “forced displacement force”). At this time, the side plate was fixed at one side. This was the force envisioned to be applied when the side plate thermally expanded. A small force means a small thermal stress, so is preferable. This calculation was performed for cases of cutting and no cutting of the bridge portions 7d.
The inventors ran simulation calculations under the above conditions. The results are shown in FIG. 7. The fact that type 1 of the first embodiment according to the present invention is the most suitable when considering the stability during brazing and the thermal stress during thermal expansion is clear from the results of the calculation of FIG. 7. That is, if comparing type 1 and the conventional example of type 3, type 1 has a deflection δ only 26% larger than type 3, while only requires 21% of the forced displacement force (at the cutting of the bridge portions) compared with type 3. Further, comparing type 1 and type 2, type 1 has a deflection δ only 9% weaker than type 3, while only requires 60% weaker forced displacement force (at the cutting of the bridge portions) compared with type 2.
That is, the side plate of type 1, compared with type 2 and 3, did not increase in deflection that much, but was greatly reduced in forced displacement force (at the cutting of the bridge portions). This means that the stability at the time of brazing is not inhibited that much compared with the past types and the thermal stress can be greatly reduced.
Second Embodiment
Next, a second embodiment of the present invention will be explained based on FIG. 8. Note that parts having substantially the same functions as the first embodiment are assigned the same reference numerals and their explanations are omitted. The second embodiment is that of a heat exchanger 200 having separate paths through which a plurality of heat exchange media pass. The plurality of heat exchange media are, for example, vehicle transmission oil (below simply referred to as “oil”) and air-conditioning refrigerant. The heat exchanger inlet temperature of the oil is approximately 140° C., and the heat exchanger inlet temperature of the refrigerant is approximately 70° C.
FIG. 8 is an overview of the heat exchanger 200 according to the second embodiment of the present invention. Reference numeral 8 is a modulator which stores the air-conditioning refrigerant, while 71 is a conventional type of side plate with no bridge portions at all. Reference numeral 5d is an oil inlet and 5e is an oil outlet. Reference numeral 5f is a refrigerant inlet and 5g is a refrigerant outlet. Note that the inlets and outlets of the oil and refrigerant can reversed. Reference numeral 5x is a subchamber in which there is no heat exchange medium and only air. This is for detecting the leakage of oil and refrigerant for preventing the trouble of the oil and refrigerant mixing. 5z is a divider (separator) which divides the inside of the header tank 5 into a plurality of small chambers.
The side plate 7 is arranged near the tubes 2 through which the high temperature heat exchange medium, that is, the oil, passes and is easily affected by thermal expansion, so has bridge portions 7c and 7d, but the side plate 71 is arranged near the tubes 2 through which the low temperature heat exchange medium, that is, the refrigerant, passes and is resistant to the effect of thermal expansion, so does not need to have the bridge portions.
First, the circulation path of the high temperature heat exchange medium oil will be explained. Oil flowing in from the transmission (not shown) via the oil inlet 5d to the heat exchanger 200 passes from the header tank subchamber 5h to the tubes 2 in the left direction, reaches the header tank subchamber 5i, then passes through the upper tubes conversely to the right direction, reaches the header tank subchamber 5j, then flows out via the oil outlet 5e to the transmission (not shown).
Next, the circulation path of the low temperature heat exchange medium refrigerant will be explained. The refrigerant compressed by a refrigerant pump (not shown) flows in from the refrigerant inlet 5f to the heat exchanger 200, passes from the header tank subchamber 5k to the tubes 2 in the left direction, reaches the header tank subchamber 51, and flows via the modulator inlet 8b to the modulator 8. The refrigerant flowing into the modulator 8 flows in from the modulator outlet 8c to the header tank subchamber 5m, then passes through the upper tubes 2 conversely in the right direction, reaches the header tank subchamber 5n, then passes through in the upper tubes 2 to the left direction and reaches the header tank subchamber 5p. The refrigerant flowing into the header tank subchamber 5p passes through the upper tubes 2 conversely in the right direction, reaches the header tank subchamber 5q, and flows out from the refrigerant outlet 5g to an expansion valve (not shown).
The second embodiment is a single heat exchanger, so it is possible to make heat exchangers for a plurality of heat exchange media more compact. Further, it is not necessary to provide bridge portions at the side plate resistant to the effect of thermal expansion, so by employing the side plate 71 of the conventional type with no bridge portions at all, it becomes possible to eliminate unnecessary processes.
Third Embodiment
As the plurality of heat exchange media, oil and engine coolant water can be used. The heat exchanger inlet temperature of the engine coolant water is a high temperature of approximately 100° C. Because of this, in FIG. 8, it is desirable to make the side plate 71 (no bridge portions) of the lower side identical to the side plate 7 (with bridge portions) of the upper side. That is, both side plates have bridge portions.
Other Embodiments
As the heat exchanger according to the present invention, it is cover radiators for cooling inverters and other electronic components controlling electric motors in hybrid vehicles and the like.
As explained above, according to the embodiments of the present invention, it becomes possible to provide a heat exchanger enabling prevention of breakage of joints of the tubes and the side plates at the core plates, easy to produce, and reduced in cost which has side plates enabling stable brazing of the tubes and the fins with the side plates.
While the invention has been described with reference to specific embodiments chosen for purpose of illustration, it should be apparent that numerous modifications could be made thereto by those skilled in the art without departing from the basic concept and scope of the invention.
Patent Application
20080006392
