JP2008016605A - Power converter for vehicle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To assure a function for suppressing an occurrence of a runout of an operating fluid of a heatpipe, and to improve a cooling function at a low speed running of a vehicle. <P>SOLUTION: A semiconductor circuit 4 formed by a pyrogenic semiconductor element is fixed to a heat receiving part 5. One end side of the heatpipe 6 is fixed to the heat receiving part 5 so as to receive the wind entailed by the travel of the vehicle, and this one end side functions as an operating-fluid-evaporating part, and the other end side functions as an operating-fluid-condensing part. A plate heat radiating fin 7 is fixed to the heatpipe 6 at the predetermined intervals so that the plate surface is arranged in parallel with a vehicle traveling direction. A slit 7a capable of preventing the runout of the operating fluid of the heatpipe 6 is formed on the plate surface of the plate heat radiating fin 7 even though an ambient temperature becomes lower than the condensing temperature of the operating fluid. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a vehicle power converter using a heat pipe as a cooling means for a semiconductor circuit.

  The vehicle drive motor is controlled by a vehicle power conversion device such as an inverter, and the vehicle power conversion device has a semiconductor circuit formed by a heat-generating semiconductor element. Therefore, since the temperature of the semiconductor circuit rises while the vehicle is traveling, it is necessary to prevent the semiconductor element from being burned by performing cooling such as blowing cooling air to the semiconductor circuit.

  As a configuration for obtaining the cooling air, a configuration in which a blower or the like is attached in the vicinity of the semiconductor circuit is conceivable. However, a space for mounting the blower must be secured, and maintenance for the blower is performed regularly or irregularly. There is a need.

  For this reason, a configuration in which a vehicle traveling wind that is inevitably generated as the vehicle travels is used as cooling air and a blower is not used has been gradually adopted recently (for example, see Patent Document 1).

However, in the case of the configuration in which the semiconductor circuit is cooled using only the vehicle traveling wind as in Patent Document 1, sufficient cooling wind cannot be obtained when the vehicle travels at low speed. Many configurations that use cooling by a pipe are also employed (see, for example, Patent Document 2).
JP 2004-6901 A Japanese Unexamined Patent Publication No. 7-190655

  By the way, as is well known, the heat pipe used in the apparatus according to Patent Document 2 encloses a working fluid (pure water, chlorofluorocarbon, etc.) in a metal tube sealed at both ends, and further, a capillary tube is added to the working fluid. It has a structure in which a material called “wick” for causing a phenomenon is disposed in a metal tube, and one end side functions as a hydraulic fluid evaporating unit and the other end side functions as a hydraulic fluid condensing unit. And the vapor | steam of the hydraulic fluid evaporated in the evaporation part diffuses in a metal pipe, reaches | attains a condensation part, discharge | releases a latent heat, and is condensed. The hydraulic fluid condensed in the condensing part is returned to the evaporation part by the action of the wick capillarity or by the action of gravity (usually the heat pipe is mounted in an inclined state so that the condensing part side is higher). Thereafter, the same operation is repeated.

  Therefore, when a heat pipe with such a structure is used in a cold region in winter, the so-called “working fluid dripping” phenomenon that the working fluid condensed in the condensing part freezes and does not recirculate to the evaporation part often occurs. To do. When such hydraulic fluid spillage occurs, the cooling function of the heat pipe is lost, and the semiconductor element of the semiconductor circuit is burned out. Therefore, in the apparatus according to Patent Document 2, a structure that reduces the condensing capacity of the condensing unit is adopted as a measure for suppressing the occurrence of such working fluid spilling, so that the working fluid is condensed before the freezing temperature is lowered. I have to.

  However, reducing the condensing capacity in this way means reducing the cooling capacity, and the apparatus according to Patent Document 2 uses both cooling by the vehicle traveling wind and cooling by the heat pipe. When the vehicle travels at a low speed, the cooling function of the entire apparatus is significantly lowered in combination with the above-described decrease in the cooling function due to the vehicle traveling wind. Therefore, it has been difficult to sufficiently reduce the temperature of the semiconductor circuit when the vehicle is traveling at a low speed.

  The present invention has been made in view of the above circumstances, and is a vehicle power conversion capable of improving a cooling function during low-speed traveling of a vehicle while ensuring a function of suppressing the occurrence of hydraulic fluid dripping in a heat pipe. The object is to provide a device.

  As a means for solving the above-described problems, the present invention has a heat receiving portion to which a semiconductor circuit formed of a heat-generating semiconductor element is attached, and one end side attached to the heat receiving portion so as to receive the vehicle traveling wind over its entire length. The one end side acts as a hydraulic fluid evaporating part and the other end side acts as a hydraulic fluid condensing part, and is attached to the heat pipe at predetermined intervals so that the plate surface is parallel to the vehicle traveling direction, A plurality of plate-like heat dissipating fins formed with slits on the plate surface to prevent the heat pipe from dripping even when the environmental temperature is below the heat pipe hydraulic fluid condensation point; It is configured.

  ADVANTAGE OF THE INVENTION According to this invention, it becomes possible to improve the cooling function at the time of low speed driving | running | working of a vehicle, ensuring the function which suppresses generation | occurrence | production of the hydraulic fluid dripping of a heat pipe.

  FIG. 2 is an explanatory diagram showing an attachment position of the vehicle power converter according to the embodiment of the present invention. A power conversion device 3 is attached to the side of the wheel 2 below the floor of the vehicle 1.

  FIG. 1 is a perspective view showing the configuration of the power converter 3 described above. A semiconductor circuit 4 formed of an exothermic semiconductor element such as an IGBT is attached to a flat surface of a block-shaped heat receiving portion 5. And one end side of the plurality of heat pipes 6 is arranged and attached to one side surface of the heat receiving portion 5 at the attachment position for each predetermined height.

  The other end side (front end side) of the heat pipe 6 is higher than the one end side, and the heat pipe 6 is attached so as to be slightly upward as a whole. The heat pipe 6 is attached so that the axial direction is perpendicular to the vehicle traveling direction, that is, to receive the vehicle traveling wind indicated by the arrow over the entire length. And one end side of the heat pipe 6 attached to the heat receiving part 5 acts as a hydraulic fluid evaporating part, while the other end side which is the tip side acts as a hydraulic fluid condensing part.

  A plurality of plate-like radiating fins 7 are attached to the plurality of heat pipes 6 at predetermined intervals. The plate surface of each plate-like radiating fin 7 is parallel to the vehicle traveling direction of the vehicle 1, and a plurality of heat pipes 6 are inserted through the plate surface.

  A rectangular elongated slit 7 a is formed on both sides of each heat pipe 6. FIG. 3 is a front view showing a position where the slit 7a is formed. As shown in this figure, the position in the height direction where the slit 7 a is formed is substantially the same as that of the heat pipe 6, and the width W of the slit 7 a is also substantially the same as the diameter of the heat pipe 6.

  Next, the operation of the present embodiment having the above configuration will be described. As shown in FIG. 3, the position and width in the height direction of the slit 7 a and the position and diameter in the height direction of the heat pipe 6 are made the same in the region where the heat pipe 6 exists in the height direction. R1 is a region where the temperature is uniform and there is no temperature gradient, whereas the region R2 where the heat pipe 6 does not exist is a region where there is a temperature difference and there is a temperature gradient. is there. That is, if the fin defect region is generated in the region R2 having the temperature gradient, the heat conduction performance is significantly lowered. However, it is assumed that the slit defect 7a was originally formed in the region R1 having no temperature gradient to generate the fin defect region. This is because the heat conduction performance does not decrease so much.

  In the present embodiment, by forming the slits 7 a as described above in the plate-like heat radiation fins 7, even when the environmental temperature of the power conversion device 3 is equal to or lower than the hydraulic fluid condensation point of the heat pipe 6, It is possible to suppress the occurrence of hydraulic fluid spillage in the pipe 6 and to improve the cooling performance in the low-speed traveling region of the vehicle.

  The reason why the formation of the hydraulic fluid can be suppressed by forming the slits 7a as described above is that the weight of the plate-shaped heat radiation fins 7, that is, the heat capacity can be reduced by forming the slits 7a. That is, the hydraulic fluid evaporates on one end side (heat receiving unit 5 side) of the heat pipe 6, and the vapor moves to the other end side (tip side) and condenses. Here, the latent heat of vaporization is transferred between the plate-shaped heat radiation fins 7, but the heat capacity of the plate-shaped heat radiation fins 7 is reduced due to the formation of the slits 7a, and has reached a state of thermal saturation or a state close thereto. The condensed working fluid is in a state where it is difficult to freeze even if the environmental temperature is significantly reduced.

  FIG. 4 is a characteristic diagram illustrating an example of a change state of the allowable minimum environmental temperature that can be used by the power conversion device. In this characteristic diagram, the degree of reduction of the heat capacity of the plate-shaped heat radiation fin 7 is shown by using the total volume of the slits 7a with respect to the volume of the plate-shaped heat radiation fin 7, that is, [slit volume / fin volume]. As is apparent from this figure, the upper limit of [slit volume / fin volume] is set to about 0.5, and the allowable minimum environmental temperature can be lowered as the value of [slit volume / fin volume] is increased. It has become.

  Therefore, if the value of [slit volume / fin volume] is appropriately set in consideration of the minimum temperature of the environment in which the power conversion device 3 is used (the travel region of the vehicle 1), the hydraulic fluid of the heat pipe 6 is unlikely to spill. A power converter can be obtained. However, this allowable minimum ambient temperature is not determined only by the value of [slit volume / fin volume], but other values such as the shape of the heat pipe 6, the inclination with respect to the direction of gravity, the structure of the wick, the type of hydraulic fluid, etc. It depends on conditions. The characteristic diagram of FIG. 4 assumes that these other conditions are the same.

  Further, the reason why the cooling performance in the low-speed traveling region of the vehicle can be improved by forming the slits 7a as described above is that air that contacts the heat pipes 6 and the plate-like radiating fins 7 is promoted by turbulence of the vehicle traveling wind. It is because the thermal resistance of the power converter can be reduced.

  That is, in FIG. 1, if the slits 7 a are not formed, most of the vehicle traveling wind that enters between the plurality of plate-like heat radiating fins 7 from the entire vehicle surface comes into contact with the plurality of heat pipes 6. Passes through the plate-like heat radiation fin 7 as it is. However, in the configuration of FIG. 1, a part of the traveling wind passing along the plate-shaped heat radiation fins 7 at this time changes the course in the direction perpendicular to the vehicle traveling direction through the slits 7a. In this space, the flow field (if any) is disturbed, and the pressure loss increases.

  FIG. 5 is a characteristic diagram showing the relationship between the overall wind speed and pressure loss when the vehicle 1 is traveling at a low speed, and FIG. 6 is a characteristic diagram showing the relationship between the overall wind speed and thermal resistance when the vehicle 1 is traveling at a low speed. .

  As shown in FIG. 5, the pressure loss when using the fin with a slit as in this embodiment is greatly increased as compared with the case using a fin without a slit. As the pressure loss increases, as shown in FIG. 6, the thermal resistance when using the fins with slits is significantly lower than when using the fins without slits.

  From the above, according to the configuration of FIG. 1, by forming the slits 7 a in the plate-like heat radiating fins 7, the heat capacity of the plate-like heat radiating fins 7 can be reduced, so In addition, since the pressure loss can be increased and the thermal resistance can be reduced, it is possible to improve the cooling performance during low-speed traveling.

  FIG. 7 is a characteristic diagram showing the relationship between the front wind speed and the temperature of the semiconductor circuit 4, that is, the cooling performance when the vehicle 1 is traveling at a low speed. As shown in this figure, when the cooling performance when using the fin with slit and when using the fin without slit is almost the same, when the fin without slit is used, the cooling performance is lowered to -18 ° C at most. In contrast, when a fin with a slit is used, the minimum environmental temperature can be lowered to -33 ° C.

  By the way, about the plate-shaped radiation fin 7 in which the slits 7a as described above are formed, a special effect can be obtained by applying a certain deformation, and this will be described.

  FIG. 8 is a perspective view showing a first modification of the plate-like heat radiation fin 7. In this figure, the illustration of the heat pipe 6 is omitted, and a heat pipe hole 7b is shown instead. And in the 1st modification, the projection part 7c which protruded perpendicularly | vertically with respect to the plate surface is formed in the lower edge part of the slit 7a. The protrusion 7c is formed by cutting up a portion corresponding to the slit 7a.

  By the formation of the projection 7c, the turbulence of the vehicle traveling wind is promoted, and the pressure loss shown in FIG. 5 can be further increased. Therefore, the thermal resistance shown in FIG. 6 can be further reduced.

  FIG. 9 is an explanatory view showing a second modification of the plate-shaped heat radiation fins 7, (a) is a front view showing the odd-numbered plate-shaped heat radiation fins 7 A, and (b) is an even-numbered plate. The front view which showed the heat sink fin 7B, (c) is the side view which showed the attachment state of these plate heat fin 7A, 7B.

  As shown in FIGS. 9A and 9B, the height direction position of the slit 7a1 of the plate-shaped heat radiation fin 7A and the height direction position of the slit 7a2 of the plate-shaped heat radiation fin 7B are a predetermined distance (deviation). By an amount δ). Therefore, as shown in FIG. 9 (c), the adjacent slits 7a1 and 7a2 have different heights, so that the flow of air passing through these slits is subjected to strong resistance while being bent. Therefore, even when this second modification is used, the pressure loss shown in FIG. 5 can be further increased, and the thermal resistance shown in FIG. 6 can be further reduced.

  In the above embodiment, only the case where the shape of the slit 7a is rectangular is shown, but this shape is not particularly limited, and the slit 7a is formed in various shapes such as a polygon, a circle, or an ellipse. Is possible.

The perspective view which shows the structure of the power converter device for vehicles which concerns on embodiment of this invention. Explanatory drawing which shows the attachment position of the power converter device for vehicles of FIG. The front view which shows the attachment position of the slit in the plate-shaped radiation fin of FIG. The characteristic view which shows an example of the change state of allowable minimum environmental temperature which can use the power converter device in FIG. The characteristic view which shows the relationship between the whole surface wind speed at the time of low speed driving | running | working of the vehicle power converter device which concerns on embodiment of this invention, and a conventional apparatus, and pressure loss. The characteristic view which shows the relationship between the wind speed of a whole surface at the time of low speed driving | running | working of the vehicle power converter device which concerns on embodiment of this invention, and a conventional apparatus, and thermal resistance. The characteristic view which shows the cooling performance at the time of low speed driving | running | working of the vehicle power converter device which concerns on embodiment of this invention, and a conventional apparatus. The perspective view which shows the 1st modification of the plate-shaped radiation fin which concerns on embodiment of this invention. It is explanatory drawing which shows the 2nd modification of the plate-shaped radiation fin which concerns on embodiment of this invention, (a) is the front view which showed the plate-shaped radiation fin of the odd-numbered stage, (b) is the even-numbered stage The front view which showed the plate-shaped radiation fin, (c) is the side view which showed the attachment state of these plate-shaped radiation fins.

Explanation of symbols

1: Vehicle 2: Wheel 3: Power conversion device 4: Semiconductor circuit 5: Heat receiving unit 6: Heat pipe 7: Plate-shaped heat radiation fin 7A: Odd-numbered plate-shaped heat radiation fin 7B: Even-numbered plate-shaped heat radiation fin 7a 7a1, 7a2: Slit 7b: Heat pipe hole 7c: Projection W: Slit width R1: Area without temperature gradient R2: Area with temperature gradient δ: Deviation amount

Claims (8)

A heat receiving portion to which a semiconductor circuit formed by an exothermic semiconductor element is attached;
One end side is attached to the heat receiving part so as to receive the vehicle traveling wind over the entire length, the one end side acts as a working liquid evaporation part, and the other end side acts as a working liquid condensing part,
It is attached to the heat pipe at predetermined intervals so that the plate surface is parallel to the vehicle running direction, and it is possible to prevent the heat pipe from dripping even when the environmental temperature is below the heat liquid condensation point of the heat pipe. A plurality of plate-like heat dissipating fins having slits formed on the plate surface;
A vehicle power conversion device comprising: The ratio between the volume of the slit and the volume of the plate-like heat radiation fin is a preset value,
The power converter for vehicles according to claim 1 characterized by things. A plurality of the heat pipes are arranged at attachment positions for each predetermined height, and the plurality of heat pipes are inserted through the plate surface of the plate-like heat radiation fins.
The power converter for vehicles according to claim 1 or 2 characterized by things. The slit has a width substantially equal to the diameter of the heat pipe.
The vehicular power converter according to any one of claims 1 to 3. A plurality of the slits are formed on the plate surface, and the plurality of slits includes a slit height that is substantially the same as the mounting position of the heat pipe.
The vehicular power converter according to any one of claims 1 to 4. The height direction position of each of the slits in the plurality of plate-shaped heat radiation fins is shifted by a predetermined distance from the height direction position of the slits of other adjacent plate-shaped heat radiation fins,
The power converter for vehicles according to any one of claims 1 to 5 characterized by things. At the edge of the slit, a protrusion is formed to promote turbulence of the vehicle running wind.
The vehicular power converter according to any one of claims 1 to 6. The shape of the slit is either a polygon, a circle, or an ellipse.
The power converter for vehicles according to any one of claims 1 to 7 characterized by things.

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