JP2947660B2 - Boiling cooling system for vehicles - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a control device for a vehicle, and more particularly to a cooling device for a semiconductor device.

[0002]

BACKGROUND OF THE INVENTION semi <br/> conductor converter particularly conventionally vehicle control apparatus large capacity, have been used cooling method of a semiconductor device according to often boil cooling. This cooling method is roughly classified into two methods, i.e., immersion boiling cooling and individual fin boiling cooling. Figure 12 shows the individual fins type boiling cooling system of this, heating element 1 and the cooling fins 2
Are stacked alternately, and a stack 5 is assembled by a disc spring 3, an insulating seat 4, and the like. On the other hand, cooling fin 2 has
As shown in FIG. 1, a steam pipe constituted by a liquid return pipe 8, a bellows 9, an insulating pipe 10 and the like communicating with a tank 7 for storing a refrigerant 6 is provided as a double pipe structure. 11 is a condenser.

In the above-described structure, the refrigerant 6 is saturated and boiled by the heating element 1 and vaporized. The vapor 6a rises from the tank 7 through the vapor pipe to the condenser 11 to be cooled, and the droplet 6b is cooled. become a return to the tank 7, again liquid return pipe 8
And returns to the cooling fin 2. By this repetition, the heat generated in the heating element 1 is efficiently radiated to the atmosphere. The above is the principle of the individual fin-type boiling cooling.

[0004] Since from the cooling fins 2 prior to increasing the heat dissipation area, longitudinal section of FIG. 14 and FIG. 14 larger
As shown in FIG. 15 shows a diagram, inside provided a number of grooves 2a in parallel to the liquid return pipe 8, a large number of fins by the grooves 2a (hereinafter, referred to as protrusions) 2b is formed, further the both ends of each groove 2a Is provided so as to communicate with the outside of the liquid return pipe 8 of the steam pipe having a double pipe structure.
The cooling fin 2 is made of a material having good heat conductivity such as copper, for example, and has a groove 2a and a protrusion 2 as shown in FIG.
b, an upper half portion and a lower half portion which have been processed in advance in the annular groove 2c and the like are joined together, and an annular edge is joined to the outer periphery of the joined portions. In addition, the liquid return pipe 8 constituting the steam pipe has an intermediate portion connected via an insulating tube (not shown).

[0005]

As is well known, as the refrigerant 6 used for boiling cooling, a refrigerant called as Freon R113 has been used in many cases. It is beginning to be banned. Under such circumstances, we are looking for a refrigerant to substitute for CFC R113, but we can't find anything equivalent or better. Began to be used as an alternative refrigerant.
This flolinate typically has a latent heat of about 2/3 lower than that of Freon R113, and deteriorates the burnout characteristic, which is a typical characteristic of boiling cooling, including this characteristic.

FIG. 16 is a diagram for explaining this. In general, as the refrigerant temperature T rises, the burnout heat flux q _BO increases. For example, the curve a in FIG.
Assuming that it corresponds to 113, curve b corresponds to florinate, and its value is less than about 50 to 60% (note that curve b is drawn based on a typical burnout empirical formula). . Here, what is particularly problematic is the value of the burnout heat flux at a low temperature. As will be described below, another tendency in recent years is that the amount of heat generated increases due to the increase in the capacity of the element, and the heat flux also increases. A first problem is that when the vehicle control device using the large-capacity element starts at a low temperature, burnout does not occur.

[0007] Next, the increase in the capacity of the vehicle drive circuit or the consolidation of the control device results in an increase in the capacity of the element. For example, a GTO with a breaking capacity of 3000 A
In recent years, the breaking capacity has been
The demand for 4000A ones has increased. As a result, the heat loss per element is inevitably increased, and the responsibility of the cooling fin as a side for processing the heat loss is also increased. Therefore, the above-described problem of the transient characteristics (burnout characteristics) and the problem of the poor steady-state thermal characteristics also arise.

That is, the poor refrigerant characteristics represented by the low latent heat greatly influences the steady-state boiling heat conductivity. In other words, even if the cooling fins have the same shape, the thermal resistance becomes worse. FIG. 17 is a diagram for explaining this. In the figure, if the curve e corresponds to Freon R113, for example, the curve d or c is the case of Florinert under the same conditions.

FIG. 18 is a diagram generally illustrating the above-mentioned boiling curve. If curve h is Freon R113, curve f or g corresponds to florinate and burnout heat flux is obtained. It can be clearly understood that the boiling heat conductivity has decreased due to the deterioration of the thermal conductivity.

[0010] The deterioration of the steady-state thermal characteristics affects as follows. If the loss of Q (w) is assumed, the element has a breaking current of 3000.
A, since it will not change the element junction temperature (tolerance) T _j by 4000A, if the ambient temperature and T _a, T _j
→ T _a Satoshinetsu resistance R _TOTAL of the relationship is established as indicated by the following equation at any element. Here, R _jc is the thermal resistance of the element, R _fin is the thermal resistance of the cooling _fin , R _COOLER is the thermal resistance of the condenser, and if the element structure is the same, R _jc is a constant value that does not change depending on the element. Assuming that have, in the same conditions for magnitude occurs in the R _fin CFC R113 and Fluorinert, in the case of Fluorinert is necessary to suppress the thermal resistance R _COOLER condenser. This leads to, for example, an increase in the size of the condenser and an increase in the amount of ventilation. Therefore, a cooling fin thermal resistance equivalent to that of Freon R113 is required at least in the case of Fluorinert, and an increase in the loss Q in the above equation means that the required value is further increased. This is the second problem.

[0011] Further , the reason why burnout is likely to occur in the conventional cooling fin and the reason why the steady-state thermal characteristics are deteriorated will be described. (1) The amount of generated steam is increased by 3/2 times due to low latent heat, and circulation is hindered due to an increase in resistance of a pipe or the like. This results in explosive steam generation, so-called burn-out, in which the circulation deteriorates at start-up and heat is processed only by temperature gradients. (2) If the element is small, the diameter of the portion called the post is relatively small, and the loss generated at the time of startup is transferred through the area corresponding to this diameter. When this area increases,
The amount of heat per unit area, so-called heat flux, is reduced. Alternatively, a large amount of heat can be processed. That is, since this area is small, the heat flux becomes large, and burnout occurs. (3) In connection with the circulation in the item (1), the steady-state thermal characteristics inevitably deteriorate.

SUMMARY OF THE INVENTION The present invention has been made to solve the above two problems, and has an alternative refrigerant and an element (heating element).
Provided is a boiling cooling device for a vehicle provided with a cooling fin that improves a burnout heat flux at a low temperature and improves steady-state heat characteristics (thermal resistance) in response to an increase in the amount of heat generated due to an increase in the capacity of a vehicle. It is intended to be.

[0013]

SUMMARY OF THE INVENTION In order to achieve the above-mentioned object, the present invention provides a disk-shaped disk which is pressed against a side surface of a semiconductor element.
One side is connected to the cooling fin and the top of this cooling fin
And a refrigerant storage tank connected to the other side of the steam pipe.
It consists of a radiator equipped with a condenser.
An array of fin rows that form a number of grooves and a ring that connects both ends of each groove
The steam pipe has one side penetrating the fin row and the other side
Boiling for vehicles with a return pipe connected to the refrigerant storage tank
In the cooling device, the cross groove intersecting with the fin row is
It is characterized in that it is formed in a fin.

[0014]

[Function] Generally, to improve the burnout heat flux, (a)
(B) Expansion of the heat transfer surface (boiling surface) at the beginning of boiling (time t = 0) (however, merely expanding the steady boiling surface is not considered very effective) ,
(C) It is effective to shorten the cycle time until the bubbles grown by boiling are released, (d) make the steam flow turbulent, (e) smooth the flow of the vapor liquid, etc., and especially (a) And (b) have the greatest effect.

On the other hand, as for the steady thermal characteristics, the expansion of the boiling area and the above-mentioned (c) to (e) are similarly effective, and a combined effect thereof is also expected. Here, a description will be given of a temperature rise when burnout actually occurs. As shown in FIG. 9, it appears to rise linearly instantaneously, and then rises in an exponential curve, but continues to rise sharply as the slope of the rise increases. This curve does not reach a critical burnout (melting point) because the temperature of the refrigerant has also risen, but it far exceeds the destruction temperature as a heating element. FIGS. 10 and 11 are typical rising curves, with the rising straight line being the same and then changing with an exponential curve.

Therefore, increasing the outermost diameter of the portion where the groove is provided as in the means of the present invention described above is effective because it instantaneously increases the heat transfer area against burnout. Since the post diameter of the heating element increases with an increase in the capacity of the heating element, the outer diameter of the cooling fin also increases, and the outermost diameter of the portion where the groove is provided necessarily increases.
Further, by providing a steam space inside, a buffer region is provided for an explosive steam flow at start-up or a steady continuous steam generation, a smooth steam flow is formed, and a cooling effect is improved.

[0017]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a sectional view showing one embodiment of the present invention.
In the figure, 6 is a refrigerant, 7 is a tank, 8a is a liquid return pipe, 9a is a bellows, 10a is an insulating pipe, 11 is a condenser, 12 is a cooling fin, and a liquid return pipe 8a, a bellows 9a, and an insulating pipe 10a. Constitutes a double structure steam pipe. Here, the cross section of the portion where the evaporated refrigerant 6a flows in the vapor pipe is made larger than that of the conventional one, and the inner diameter of the liquid return pipe 8a is also made larger than that of the conventional one. The liquid return pipe 8a has an intermediate portion connected via an insulating tube (not shown) as in the conventional case.

As shown in FIG. 2, the cooling fin 12 has a large number of grooves 12a provided therein in parallel with the liquid return pipe 8a.
Many protrusions 12b are formed by 12a. Each groove 12a communicates with the annular groove 12c at both ends. In addition, a projection 12b is partially cut out at the upper end, which is the end of the groove 12a, as viewed from the flow direction of the refrigerant vapor in the cooling fin 12, so that a large vapor space is formed.
Form 12d. Further, as shown in FIG. 3, the outermost diameter of the portion where the groove 12a is provided is D ₁ , and the depth of the groove 12a is T ₁ ,
The outer diameter of the portion providing grooves 12 a of the conventional cooling fin 12 as shown in 15 D _2, when the depth of the groove 2a was T _2, D ₁
> D ₂ , T ₁ > T ₂ .

This embodiment (hereinafter referred to as a first embodiment)
Is the heat transfer area increases by increasing the outer diameter D ₁ of the portion providing grooves 12a, also, by forming the vapor space 12d, which is continuous explosive vapor stream or steady startup It serves as a temporary flow buffer region for the generation of steam, and greatly contributes to smoothing the steam or liquid flow. On the other hand, by providing the steam space 12d , the heat transfer area is reduced by that amount, which does not contribute to the improvement of the steady-state thermal characteristics. However,
Since a larger outer diameter D ₁ of the portion providing the groove 12a,
The resulting increase in the heat transfer area results in improved characteristics. To describe this relationship with reference to FIG. 17 described above, equivalent of that curve e shown in FIG shifts the curve e _1, 10 to 15%
Be improved.

The present invention is not limited to the above-described embodiment, but can be variously modified. FIG. 4 shows another embodiment of the present invention (hereinafter, referred to as a second embodiment).
It is sectional drawing which shows the principal part (cooling fin). As shown in the figure, the cooling fin 13 has a large number of grooves 13a provided therein in parallel with the liquid return pipe 8a, and a large number of projections formed by these grooves 13a.
Form 13b. Each groove 13a communicates with the annular groove 13c at both ends. In addition, the groove 13a and the protruding portion 13b are divided into upper and lower two stages, and the width is set to be smaller than the width of the groove 13a along the direction orthogonal to the groove 13a.
Wide Kushida providing a groove 13d. Further, the outermost diameter of the portion where the groove 13a is provided and the depth of the groove 13a are configured to have the same relationship as that of the first embodiment described above with respect to the subordinate cooling fin 2.

In the second embodiment, the heat transfer area is increased as in the first embodiment described above, and the steam is made turbulent by dividing the upper and lower stages and providing a groove 13d in the middle stage. In addition, the groove serves as a spreading space for the steam generated at the lower stage due to the division, and serves as a temporary buffer region for the flow. Since Fluorinert has a low latent heat, the amount of generated steam becomes 3/2 of the same amount of heat of Freon R113, and a smooth flow can be realized by providing a buffer region for continuous generation of steam. By ensuring the turbulence and the buffer region, it effectively contributes to burnout and steady thermal characteristics. This corresponds to the curve e ₂ shown in FIG.
30-35% improvement effect.

FIG. 5 is a sectional view showing a main part (cooling fin) of still another embodiment (hereinafter, referred to as a third embodiment) of the present invention. As shown in the figure, the cooling fin 14 is arranged so that the liquid return pipe 8a passes through the center 0, and has a number of grooves 14a provided therein in parallel with the liquid return pipe 8a. Form 14b. Each groove 14a communicates with the annular groove 14c at both ends. Also, as shown in FIG.
14b is partially cut off, large vapor space 14d, liquid return pipe 8a
The projections 14b are also partially cut out at the oblique upper and lower portions in a direction perpendicular to the direction of the arrow to form steam spaces 14e and 14f. Further, FIG.
The outermost diameter of the portion where the groove 14a is provided is D ₁ ,
When the depth of 14a was T _1, configured such that _{D 1> D 2, T 1} > T 2 as in the first embodiment described above.

In the third embodiment, the heat transfer area is increased as in the first embodiment, and the steam spaces 14d, 14e,
By forming the 14f, it is equivalent to the provision of the buffer region of the first and second embodiments described above, which is effective for realizing a smooth steam flow, and has burnout and steady thermal characteristics. Works effectively. However, due to the position of the leading end of the liquid return pipe 8a, the slow flow of the liquid of the large number of refrigerants has an effect, and the characteristics are slightly lower than in the first embodiment when compared with the conventional example.

FIG. 7 is a sectional view showing a main part (cooling fin) of still another embodiment (hereinafter, referred to as a fourth embodiment) of the present invention. As shown in FIG.
A number of grooves 15a are provided in parallel with the liquid return pipe 8a, and a number of protrusions 15b are formed by these grooves 15a. Each groove 15
a communicates with the annular groove 15c. Further, similarly to the above-described second embodiment, the projecting portion 15b is divided into upper and lower stages and the groove 15a is formed.
A groove 15d is provided along the direction perpendicular to the direction of the arrow and having a width larger than that of the groove 15a, and parallel grooves 15e, 15f are provided on both sides of the groove 15d as shown in FIG.
The depth f is shallower than the groove 15a due to the mechanical strength of the protrusion 15b (which opposes the tightening force when assembled in a stack). Further, the outermost diameter of the portion where the groove 15a is provided and the groove 13a
Are configured to have the same relationship as in the first embodiment described above.

In the fourth embodiment, the heat transfer area is increased in the same manner as in the first embodiment, and shallow grooves 15d, 15e and 15f provided in a direction perpendicular to the grooves 15a are provided. Part of the flow of the refrigerant vapor along the groove 15a can be separated from the main flow, resulting in turbulent flow, which effectively affects the steady-state thermal characteristics. However, although the buffer area is not as expected as in the first and second embodiments, the turbulence effect and the like make it 10 times less than the conventional one equivalent to the first embodiment.
A ~ 15% improvement is expected.

[0026]

According to the present invention as described above, according to the present invention, the semi
A disk-shaped cooling fin pressed against the side surface of the conductive element;
A steam pipe with one side connected to the top of the cooling fin of
A discharge port connected to the other side of the steam pipe and equipped with a refrigerant storage tank and condenser
The cooling fins are formed with multiple grooves.
Fin row and annular grooves communicating both ends of each groove.
One side of the pipe penetrates the fin row and the other side connects to the refrigerant storage tank
In a vehicle boiling cooling system with a return pipe
Te, since <br/> forming a cross groove intersecting the fin rows to the cooling fins, the cold start according to an alternative refrigerant to improve the burnout heat flux including low temperatures and possible, to improve the transient thermal properties The present invention can be applied to a large-capacity element, realizes centralization and large-capacity devices, and eliminates the necessity of increasing the size of a cooler, a blower, and the like.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a configuration of an embodiment of the present invention.

FIG. 2 is a sectional view showing a main part of one embodiment of the present invention.

FIG. 3 is a sectional view taken along line AA of FIG. 2;

FIG. 4 is a sectional view showing a main part of another embodiment of the present invention.

FIG. 5 is a sectional view showing a main part of still another embodiment of the present invention.

FIG. 6 is a sectional view taken along line BB of FIG. 5;

FIG. 7 is a sectional view showing a main part of still another embodiment of the present invention.

FIG. 8 is a sectional view taken along the line CC in FIG. 7;

FIG. 9 is a curve diagram showing a relationship between a time when a burnout occurs and a temperature rise related to the present invention.

FIG. 10 is a curve diagram showing a relationship between a time when a burnout occurs and a temperature rise different from FIG. 9;

FIG. 11 is a curve diagram showing a relationship between a time when a burnout occurs and a temperature rise different from those in FIGS. 9 and 10;

FIG. 12 is a front view showing a configuration of a conventional vehicle boiling cooling device.

FIG. 13 is a cross-sectional view of the vehicular boiling cooling device shown in FIG.

FIG. 14 is a cross-sectional view of a cooling fin used in a conventional vehicle boiling cooling device.

FIG. 15 is a sectional view taken along line DD of FIG. 14;

FIG. 16 is a curve diagram of a burnout heat flux obtained by an empirical formula.

FIG. 17 is a boiling curve diagram showing up to a nucleate boiling region related to the present invention.

FIG. 18 is a typical boiling curve diagram of boiling related to the present invention.

[Explanation of symbols]

1 ... heating element, 6 ... refrigerant, 6a ... vapor, 6b ... droplet,
7: tank, 8a: liquid return pipe, 11: condenser, 12, 13, 1
4, 15 ... cooling fins, 12a, 13a, 13d, 14a, 15a, 1
5d, 15e, 15f: groove, 12b, 13b, 14b, 15b: fin, 12c, 13c, 14c, 15c: annular groove, 12d, 14d, 14
e, 14f: steam space.

Claims (1)

(57) [Claims] 1. A disk-shaped member pressed against a side surface of a semiconductor element.
One side is connected to the cooling fin and the top of this cooling fin
And a refrigerant storage tank connected to the other side of the steam pipe.
It consists of a radiator equipped with a condenser.
The fin row forming a plurality of grooves and both ends of each of the grooves are
An annular groove communicating with the steam pipe is provided.
Return pipe that penetrates the cooling line and is connected to the refrigerant storage tank on the other side
Wherein the fins
A boiling cooling device for a vehicle , wherein an intersecting groove intersecting with a row is formed in the cooling fin .