WO2021005650A1 - Servo amp - Google Patents

Abstract

A servo amp comprising a circuit board and a radiator that dissipates heat to a fluid flowing along a first direction parallel to the circuit board. The radiator has: a base plate; a plurality of fins that extend from the base plate in a second direction that intersects the circuit board and are lined up parallel to a third direction that is parallel to the circuit board and orthogonal to the first direction; a first protrusion formed in at least one fin and extending along the second direction; and a second protrusion formed in at least one fin, extending along the second direction, and arranged further on the downstream side than the first protrusion, in the flow of the fluid. The length of the second protrusion in the second direction is greater than the length of the first protrusion in the second direction.

Description

servo amplifier

The present invention relates to a servo amplifier that controls a servomotor.

Patent Document 1 describes a servo amplifier. This servo amplifier has a heat sink provided with heat dissipation fins, a case cover assembled to the heat sink, and a main circuit board housed in the case cover. A power semiconductor device superimposed on a heat sink is mounted on the rear part of the main circuit board. An electrolytic capacitor is mounted on the front part of the main circuit board. The electrolytic capacitor is housed in a substrate storage space formed in front of the installation space of the power semiconductor device and the heat sink. The space for installing the power semiconductor device and heat sink and the space for storing the substrate are separated by a heat shield plate. As a result, the heat released from the power semiconductor device and the heat sink is blocked by the heat shield plate, so that the temperature rise in the substrate storage space is suppressed.

Japanese Patent No. 6015405

The servo amplifier is equipped with a servo lock function that keeps the servo motor stopped even when an external force is applied. When the servo lock state is reached after continuous operation of the servo motor, a larger current flows through the servo amplifier for several seconds than during continuous operation. That is, when the servo lock state is reached after continuous operation, the servo amplifier performs instantaneous high heat generation operation in which the amount of heat generated temporarily increases. Therefore, the radiator provided in the servo amplifier needs to be designed so that the temperature of the semiconductor element satisfies the allowable temperature in consideration of the temperature rise in the instantaneous high heat generation operation in addition to the temperature rise in the continuous operation. ..

However, in order to suppress not only the temperature rise during continuous operation but also the temperature rise during instantaneous high heat generation operation due to the heat radiation from the radiator provided in the servo amplifier, it is necessary to increase the heat dissipation area of the radiator. There is. Therefore, the conventional servo amplifier has a problem that the radiator becomes large.

The present invention has been made to solve the above-mentioned problems, and an object of the present invention is to provide a servo amplifier capable of suppressing an increase in size of a radiator.

The servo amplifier according to the present invention is arranged on a circuit board, at least one semiconductor element mounted on one surface of the circuit board, and the other surface of the circuit board, and is arranged in a first direction parallel to the circuit board. The radiator comprises a radiator that radiates heat to the fluid flowing along the circuit board, and the radiator includes a base plate arranged in parallel with the circuit board and the radiator along a second direction intersecting the circuit board from the base plate. Formed into a plurality of fins extending in a direction away from the circuit board and parallel to the circuit board at intervals in a third direction parallel to the circuit board and orthogonal to the first direction, and at least one of the plurality of fins. The first protrusion formed in the first projection body extending along the second direction and at least one of the plurality of fins, extending along the second direction, and the first in the flow of the fluid. It has a second protrusion arranged on the downstream side of the protrusion, and the widths of the first protrusion and the second protrusion in the third direction are the widths of the first protrusion and the second protrusion in the third direction. It is wider than the width of each of the plurality of fins, and the length of the second protrusion in the second direction is longer than the length of the first protrusion in the second direction.

According to the present invention, it is possible to realize a servo amplifier that can suppress the increase in size of the radiator.

It is a perspective view which shows the structure of the servo amplifier which concerns on Embodiment 1 of this invention. It is a perspective view which shows the structure of the control equipment part of the servo amplifier which concerns on Embodiment 1 of this invention. It is a front view which shows the structure which looked at the control equipment part of the servo amplifier which concerns on Embodiment 1 of this invention in the + x direction. It is a top view which shows the structure which looked at the control equipment part of the servo amplifier which concerns on Embodiment 1 of this invention in the + z direction. It is a graph explaining the effect of the servo amplifier which concerns on Embodiment 1 of this invention. It is a top view which shows the structure which looked at the control equipment part of the servo amplifier which concerns on Embodiment 2 of this invention in the + z direction.

Embodiment 1.
The servo amplifier according to the first embodiment of the present invention will be described. Servo amplifiers are configured to control servomotors used, for example, in factory production lines. The servo amplifier is provided with a servo lock function that holds the servo motor in a stopped state even when an external force is applied, in addition to a continuous operation function in which a current is continuously passed through the servo motor.

FIG. 1 is a perspective view showing the configuration of the servo amplifier 100 according to the present embodiment. In FIG. 1, the flow direction of air, which is a cooling medium, that is, the wind direction is indicated by a thick arrow. As shown in FIG. 1, the servo amplifier 100 includes a command unit 10 that outputs a command for operating the movement of a servo motor (not shown), and a control device unit that sends a current to the servo motor based on a command from the command unit 10. It has 20 and. The control device unit 20 includes a circuit board 21, a plurality of semiconductor elements 31, 32, 33 mounted on one surface of the circuit board 21, and a heat sink 40 arranged on the other surface of the circuit board 21. doing. When the servo lock function is executed and the servo lock state is entered, a larger current than during continuous operation is sent to each of the plurality of semiconductor elements 31, 32, 33 by a command from the command unit 10. As a result, when the servo-locked state is reached after continuous operation, the amount of heat generated by each of the plurality of semiconductor elements 31, 32, and 33 is larger than that during continuous operation for several seconds. That is, when the servo lock state is reached after continuous operation, the control device unit 20 performs instantaneous high heat generation operation in which the amount of heat generated temporarily increases.

The heat sink 40 is a radiator configured to cool a plurality of semiconductor elements 31, 32, 33 by radiating heat to the air. The heat sink 40 has a flat plate-shaped base plate 41 arranged along the other surface of the circuit board 21, and a plurality of fins 42 extending from the base plate 41 in a direction away from the circuit board 21. There is. Each of the plurality of fins 42 has a rectangular flat plate shape. Each of the plurality of fins 42 may have a pin-like shape. The heat generated by the plurality of semiconductor elements 31, 32, 33 is transferred to the heat sink 40. The heat transferred to the heat sink 40 is dissipated to the air passing through the air passage formed between the two fins 42 adjacent to each other. As the material of the heat sink 40, for example, aluminum having high thermal conductivity and good workability is used.

Each of the plurality of semiconductor elements 31, 32, 33 is an element that generates heat by the current sent from the command unit 10. In each of the plurality of semiconductor elements 31, 32, 33, in addition to generating heat during continuous operation in a steady state, instantaneous high heat generation occurs in a servo-locked state after continuous operation. Each of the plurality of semiconductor elements 31, 32, 33 is a power module such as an IGBT (Insulated Gate Bipolar Transistor) or a diode. The semiconductor element 31 is arranged on the windward side of the plurality of semiconductor elements 31, 32, 33. The semiconductor element 32 is arranged on the leeward side of the plurality of semiconductor elements 31, 32, 33. The semiconductor element 33 is arranged on the leeward side of the semiconductor element 31 and on the leeward side of the semiconductor element 32. That is, the semiconductor element 31, the semiconductor element 33, and the semiconductor element 32 are arranged in this order on the circuit board 21 from the windward side to the leeward side.

Here, in this embodiment, the following coordinate system is adopted. The x-axis is taken along the wind direction in a plane parallel to the base plate 41, and the direction from the windward side to the leeward side is the + x direction. The y-axis is taken along the direction orthogonal to the x-axis in a plane parallel to the base plate 41. The xy plane parallel to both the x-axis and the y-axis is parallel to the base plate 41. The z-axis is taken along the direction intersecting the xy plane. The z-axis is orthogonal to, for example, the xy plane. Each of the plurality of fins 42 is arranged along the z-axis. The direction from the tip 43 side of each of the plurality of fins 42 toward the base plate 41 is the + z direction. The xz plane parallel to both the x-axis and the z-axis is parallel to each of the plurality of fins 42.

As shown in FIGS. 2 to 4 described later, the plurality of fins 42 of the present embodiment are 10 fins 42a, 42b, 42c, 42d, 42e, 42f, 42g arranged side by side at intervals in the y-axis direction. , 42h, 42i, 42j. In the figure, the intervals of the plurality of fins 42 in the y-axis direction are equal intervals, but they may be unequal intervals. Each of the fins 42a, 42b, 42c, 42d, 42e, 42f, 42g, 42h, 42i, 42j extends along the z direction. The lengths of the fins 42a, 42b, 42c, 42d, 42e, 42f, 42g, 42h, 42i, and 42j in the z-axis direction are the same. The heat sink 40 of the present embodiment is a natural air cooling system using natural convection of air. In the natural air cooling method, the wind direction is vertically upward. Therefore, the heat sink 40 and the control device unit 20 including the heat sink 40 are installed in such a posture that the −x direction is vertically downward.

FIG. 2 is a perspective view showing the configuration of the control device unit 20 of the servo amplifier 100 according to the present embodiment. FIG. 2 shows the configuration of the control device unit 20 cut in a plane parallel to the xz plane. FIG. 3 is a front view showing a configuration in which the control device unit 20 of the servo amplifier 100 according to the present embodiment is viewed in the + x direction. FIG. 4 is a plan view showing a configuration in which the control device unit 20 of the servo amplifier 100 according to the present embodiment is viewed in the + z direction.

As shown in FIGS. 2 to 4, each of the plurality of semiconductor elements 31, 33, 32 is arranged so as to overlap at least one of the plurality of fins 42 when viewed along the z-axis direction. There is. In the present embodiment, the plurality of semiconductor elements 31, 33, 32 are all arranged so as to overlap the fins 42e when viewed along the z-axis direction.

A plurality of protrusions 51, 53, 52 are formed on the fin 42e. The number of protrusions 51, 53, 52 formed on the fins 42e is the same as the number of semiconductor elements 31, 33, 32 that overlap with the fins 42e when viewed along the z-axis direction. The protrusions 51, 53, and 52 are arranged so as to overlap the semiconductor elements 31, 33, and 32 when viewed along the z-axis direction. That is, the protrusions 51, 53, and 52 are arranged in this order from the leeward side to the leeward side. The width W1 of the protrusion 51 in the y-axis direction is larger than the width W0 of the fins 42e in the y-axis direction (W1> W0). The width of the protrusion 53 in the y-axis direction and the width of the protrusion 52 in the y-axis direction are also larger than the width W0 of the fins 42e in the y-axis direction. Each of the width of the protrusion 53 in the y-axis direction and the width of the protrusion 52 in the y-axis direction is equal to, for example, the width W1 of the protrusion 51 in the y-axis direction. Each of the protrusions 51, 53, and 52 is made of the same material as the fin 42e and is integrally formed with the fin 42e. Each of the protrusions 51, 53, and 52 is, for example, a medium entity having no internal cavity.

Each of the protrusions 51, 53, and 52 extends in the −z direction from the contact portion between the base plate 41 and the fin 42e. The length L1 of the protrusion 51 in the z-axis direction, the length L3 of the protrusion 53 in the z-axis direction, and the length L2 of the protrusion 52 in the z-axis direction are all the length L0 of the fin 42e in the z-axis direction. Shorter than (L1 <L0, L3 <L0, L2 <L0). That is, in each of the protrusions 51, 53, and 52, the end portion in the + z direction is connected to the base plate 41, and the end portion in the −z direction is located on the + z side of the tip portion 43 of each fin. ..

Each of the protrusions 51, 53, and 52 has an elliptical shape in a cross section parallel to the xy plane. In the same cross section, the major axis direction of each of the protrusions 51, 53, 52 is parallel to the x-axis, and the minor axis direction of each of the protrusions 51, 53, 52 is parallel to the y-axis. The protrusions 51, 53, and 52 have, for example, the same cross-sectional shape.

The protrusion 51 has a protrusion 51a protruding from the fin 42e in the −y direction and a protrusion 51b protruding from the fin 42e in the + y direction. Each of the protrusions 51a and 51b has a semi-elliptical shape in a cross section parallel to the xy plane. The protrusion 51 may be formed only by the protrusion 51a or the protrusion 51b. Similarly, the protrusion 53 has a protrusion 53a protruding from the fin 42e in the −y direction and a protrusion 53b protruding from the fin 42e in the + y direction. Each of the protrusions 53a and 53b has a semi-elliptical shape in a cross section parallel to the xy plane. The protrusion 53 may be formed only by the protrusion 53a or the protrusion 53b. The protrusion 52 has a protrusion 52a protruding from the fin 42e in the −y direction and a protrusion 52b protruding from the fin 42e in the + y direction. Each of the protrusions 52a and 52b has a semi-elliptical shape in a cross section parallel to the xy plane. The protrusion 52 may be formed only by the protrusion 52a or the protrusion 52b.

The length L1 of the protrusion 51 located on the leeward side of the protrusions 51, 53, 52 in the z-axis direction is the z-axis direction of the protrusion 52 located on the leeward side of the protrusions 51, 53, 52. Is shorter than the length L2 in (L1 <L2). The length L3 of the protrusion 53 in the z-axis direction is equal to or greater than the length L1 of the protrusion 51 in the z-axis direction (L3 ≧ L1) and equal to or less than the length L2 of the protrusion 52 in the z-axis direction (L3 ≦ L2). ) Is preferable. For example, the lengths L1, L3 and L2 satisfy the relationship L1 <L3 <L2.

In the present embodiment, each of the protrusions 51, 53, and 52 is provided on one fin 42e. However, each of the protrusions 51, 53, and 52 may be provided so as to straddle a plurality of fins. For example, when the semiconductor element 31 straddles a plurality of fins when viewed along the z-axis direction, the protrusion 51 may be provided straddling the plurality of fins. ..

Next, the heat dissipation path from the control device unit 20 will be described. In the semiconductor elements 31, 33, and 32 during continuous operation, a substantially constant amount of heat continues to be continuously generated. The heat generated by the semiconductor elements 31, 33, 32 is first transferred to the base plate 41. The heat transferred to the base plate 41 spreads to some extent in the xy plane, and a part of the heat is dissipated from the base plate 41 to the air. Other heat is transferred to the plurality of fins 42 and the plurality of protrusions 51, 53, 52 by heat conduction, and is dissipated to the air from the plurality of fins 42 and the plurality of protrusions 51, 53, 52. Air convection occurs near the surfaces of the base plate 41, the plurality of fins 42, and the plurality of protrusions 51, 53, 52. In the case of natural air cooling, air convection is caused by the generation of buoyancy due to the difference in air density. Since the density of air decreases as the temperature rises, the air whose temperature has risen due to heat dissipation rises vertically upward, that is, in the + x direction. As a result, a flow of air is generated in the + x direction, and the heat continuously generated by the semiconductor elements 31, 33, and 32 continues to be dissipated to the air. The temperatures of the semiconductor elements 31, 33, and 32 during continuous operation rise to a certain temperature and become saturated.

On the other hand, in the semiconductor elements 31, 33, 32 during the instantaneous high heat generation operation, a larger amount of heat is generated for several seconds than during the continuous operation. The heat generated by the semiconductor elements 31, 33, 32 during the instantaneous high heat generation operation is transferred to the plurality of fins 42 and the plurality of protrusions 51, 53, 52 via the base plate 41. The heat sink 40 of the present embodiment has a larger heat capacity by the amount of the protrusions 51, 53, and 52. Further, the protrusions 51, 53, and 52 have a larger mass per surface area than the base plate 41 and the plurality of fins 42. Therefore, among the heat sinks 40, the protrusions 51, 53, and 52 in particular function as a heat storage unit that stores the transferred heat. For example, the protrusion 51 mainly stores heat generated by the semiconductor element 31, the protrusion 53 mainly stores heat generated by the semiconductor element 33, and the protrusion 52 mainly stores heat generated by the semiconductor element 32. Store heat. The heat storage unit serves as a buffer that fills the difference between the amount of heat generated per hour and the amount of heat released. The heat stored in the heat storage unit is gradually dissipated to the air.

Since the heat generated during instantaneous high heat generation operation is temporary, it is unlikely that heat is dissipated by air convection, unlike continuous heat generation during continuous operation. That is, the instantaneous high heat generation operation is completed until the heat generated by the semiconductor elements 31, 33, 32 during the instantaneous high heat generation operation reaches the air and becomes saturated. Therefore, in order to suppress the temperature rise of the semiconductor elements 31, 33, 32 during the instantaneous high heat generation operation, the heat sink 40 having a heat storage effect and a large heat capacity is effective. The heat capacity is represented by the product of specific heat and mass. Therefore, the heat capacity of the heat sink 40 can be increased by increasing the specific heat and one or both values of the heat sink 40. By increasing the heat capacity of the heat sink 40, it is possible to suppress the temperature rise of the semiconductor elements 31, 33, 32 during the instantaneous high heat generation operation.

Specific heat is the amount of heat required to raise the temperature of a substance with a mass of 1 kg by 1 K. The unit of specific heat is [J / (kg · K)]. The specific heat represents the difficulty of warming a substance. That is, the larger the specific heat, the less likely it is that the temperature will rise in a short time. The specific heat value depends on the substance. For example, a heat storage material having a specific heat larger than that of the heat sink 40 is provided around the heat sink 40 or around the semiconductor elements 31, 33, and 32. As a result, the heat capacity is increased by the amount of the heat storage material, so that the temperature rise of the semiconductor elements 31, 33, and 32 during the instantaneous high heat generation operation can be suppressed.

The heat capacity of the heat sink 40 can also be increased by increasing the mass of the heat sink 40. For example, like the protrusions 51, 53, and 52 of the present embodiment, only the shape is changed without changing the material of the heat sink 40, and the mass of the heat sink 40 is partially increased. As a result, the heat capacity of the heat sink 40 can be increased while suppressing an increase in manufacturing cost.

Any of the above methods for increasing the heat capacity may cause a decrease in the heat dissipation area of the heat sink 40 or a decrease in the cross-sectional area of the flow path through which air passes. Therefore, as compared with a heat sink in which only heat dissipation during continuous operation is taken into consideration, the heat sink 40 having an increased heat capacity may have a lower heat dissipation performance during continuous operation. However, in the servo amplifier 100 in which the instantaneous high heat generation operation is performed after the continuous operation, not only the temperature rise during the continuous operation can be suppressed, but also the temperature rise range during the continuous operation and the temperature rise range during the subsequent instantaneous high heat generation operation. A design that can reduce the total of, is required.

In the heat sink of the conventional servo amplifier, a large heat dissipation area is secured in order to improve the heat dissipation performance. However, in order to suppress not only the temperature rise during continuous operation but also the temperature rise during instantaneous high heat generation operation due to heat dissipation from the heat sink, it is necessary to increase the heat dissipation area of the heat sink. Therefore, in order for the temperature of the semiconductor element to satisfy the allowable temperature, there is a problem that the heat sink needs to be made larger or the input current amount needs to be limited.

On the other hand, the heat sink 40 of the present embodiment is configured to suppress not only the temperature rise during continuous operation but also the temperature rise during instantaneous high heat generation operation. Therefore, in the heat sink 40 of the present embodiment, it is possible to reduce the sum of the temperature rise width during continuous operation and the temperature rise width during the subsequent instantaneous high heat generation operation. Therefore, according to the present embodiment, it is possible to suppress the increase in size of the heat sink 40. Further, in the present embodiment, it is not always necessary to limit the amount of input current.

In the heat sink 40 of the present embodiment, each of the protrusions 51, 53, and 52 extends in the −z direction from the contact portion between the base plate 41 and the fin 42e. The length L1 of the protrusion 51, the length L3 of the protrusion 53, and the length L2 of the protrusion 52 are all shorter than the length L0 of the fin 42e. With this configuration, in addition to the heat generated by the semiconductor elements 31, 33, 32 being easily transferred to the tip 43 side of the fin 42e during continuous operation, the fin 42d and the fin on the tip 43 side of the fin 42e A wide distance from each of the 42f is secured. Therefore, the semiconductor elements 31, 33, and 32 can be efficiently cooled. On the other hand, during the instantaneous high heat generation operation, the heat capacity of the heat sink 40 increases by the amount of the protrusions 51, 53, 52, so that the temperature rise of the semiconductor elements 31, 33, 32 can be suppressed.

The semiconductor element 32 is located on the downstream side of the semiconductor element 31 and the semiconductor element 33 due to the flow of air. Therefore, the semiconductor element 32 is cooled by the air whose temperature has already risen due to the removal of heat from the semiconductor element 31 and the semiconductor element 33. Therefore, during continuous operation, the temperature of the semiconductor element 32 becomes higher than the temperature of the semiconductor element 31 and the temperature of the semiconductor element 33. As described above, during continuous operation, the temperature of the semiconductor element located on the downstream side becomes higher. On the other hand, in the present embodiment, the protrusion located on the downstream side in the air flow has a longer length in the z-axis direction. As a result, it is possible to suppress the obstruction of ventilation by the protrusions on the upstream side of the air flow. Further, since the heat capacity is larger as the protrusion is located on the downstream side, the temperature rise during the instantaneous high heat generation operation can be suppressed as the semiconductor element is located on the downstream side. Therefore, according to the present embodiment, it is possible to reduce the sum of the temperature rise width during continuous operation and the temperature rise width during the subsequent instantaneous high heat generation operation.

FIG. 5 is a graph illustrating the effect of the servo amplifier 100 according to the present embodiment. The vertical axis of the graph represents temperature. (1), (2) and (3) in the graph represent the temperatures of the three semiconductor elements in the servo amplifier 100 of the present embodiment. (1) represents the temperature of the semiconductor element 31 on the most upstream side, (2) represents the temperature of the semiconductor element 33 on the downstream side thereof, and (3) represents the temperature of the semiconductor element 32 on the most downstream side. Represents. (4), (5) and (6) in the graph represent the temperatures of the three semiconductor elements in the servo amplifier of the comparative example. The servo amplifier of the comparative example has the same configuration as that of the present embodiment except that the protrusions 51, 53, and 52 are not provided. (4) represents the temperature of the most upstream semiconductor element, (5) represents the temperature of the downstream semiconductor element, and (6) represents the temperature of the most downstream semiconductor element. There is. In addition, in each bar in the graph, the part with a dot on the lower side represents the temperature rise width during continuous operation, and the white part on the upper side represents the temperature rise width during instantaneous high heat generation operation. ing. The temperature represented by the upper end of the dotd portion is the temperature in the temperature saturated state during continuous operation. This temperature corresponds to the temperature at the time when the instantaneous high heat generation operation is started.

As shown in FIG. 5, in both the present embodiment and the comparative example, the temperature during continuous operation is higher for the semiconductor element on the downstream side. This is because, as already described, the semiconductor element on the downstream side is cooled by the air whose temperature has risen by taking heat from the semiconductor element on the upstream side.

Comparing the temperature of the semiconductor element at each position during continuous operation between the present embodiment and the comparative example, the temperature of the present embodiment is higher. That is, the temperature during continuous operation of (1) is higher than the temperature during continuous operation of (4), the temperature during continuous operation of (2) is higher than the temperature during continuous operation of (5), and (3). ) Is higher than the temperature during the continuous operation of (6). It is considered that this is due to at least one of a decrease in the heat dissipation area of the heat sink 40 due to the protrusions 51, 53 and 52 and an increase in ventilation resistance due to a decrease in the cross-sectional area of the air flow path. Therefore, when comparing only the temperatures of the semiconductor elements during continuous operation, the comparative example gives more preferable results than the present embodiment.

Comparing the temperature rise width of each semiconductor element in the comparative example during the instantaneous high heat generation operation, it can be seen that the temperature rise width of each semiconductor element is almost the same regardless of the arrangement position. That is, the temperature rise widths of (4), (5) and (6) during the instantaneous high heat generation operation are almost the same. This is because, in the configuration of the comparative example, the heat capacities around each semiconductor element are equal. On the other hand, when the temperature rise width during the instantaneous high heat generation operation of each semiconductor element of the present embodiment is compared, it can be seen that the temperature rise width is smaller as the semiconductor element is arranged on the downstream side. That is, the temperature rise width during the instantaneous high heat generation operation of (2) is smaller than the temperature rise width during the instantaneous high heat generation operation of (1), and the temperature rise width during the instantaneous high heat generation operation of (3) is (2). It is even smaller than the temperature rise during the instantaneous high heat generation operation. This is because, in the configuration of the present embodiment, the amount of heat storage is larger toward the protrusions on the downstream side.

Comparing the sum of the temperature rise width during continuous operation and the temperature rise width during instantaneous high heat generation operation of the semiconductor element at each position between the present embodiment and the comparative example, the present embodiment is smaller in both cases. It has become. That is, the sum of the temperature rises of (1) is smaller than the sum of the temperature rises of (4), the sum of the temperature rises of (2) is smaller than the sum of the temperature rises of (5), and (3). ) Is smaller than the sum of the temperature rises in (6). Further, even when the maximum values of the total sum of the temperature rises are compared between the present embodiment and the comparative example, the present embodiment is smaller. That is, the sum of the temperature rises in (6) is smaller than the sum of the temperature rises in (2). Further, in the present embodiment, the variation in the total temperature rise width depending on the position of the semiconductor element is small.

As described above, when the temperatures of the semiconductor elements during the instantaneous high heat generation operation are compared, it can be seen that the present embodiment can suppress the temperature rise of the semiconductor elements as compared with the comparative example. Since the temperature of the semiconductor element during the instantaneous high heat generation operation is higher than that during the continuous operation, the maximum temperature reached by the semiconductor element can be lowered in the present embodiment as compared with the comparative example.

As described above, since the heat sink 40 of the present embodiment is provided with the protrusions 51, 53, 52, the cross-sectional area of the air flow path is reduced as compared with the comparative example in which the protrusions are not provided. Therefore, as shown in FIG. 5, in the present embodiment, the temperature of the semiconductor element during continuous operation rises as compared with the comparative example. Each of the protrusions 51, 53, and 52 of the present embodiment has an elliptical shape in a cross section parallel to the xy plane. Further, in the same cross section, the major axis directions of the protrusions 51, 53, and 52 are parallel to the x-axis. According to this configuration, the cross-sectional shape and cross-sectional area of each yz cross section of the protrusions 51, 53, and 52 change smoothly with respect to the air flow direction. As a result, it is possible to suppress an increase in air resistance due to the protrusions 51, 53, 52 being provided on the heat sink 40, so that it is possible to suppress a temperature rise of the semiconductor element during continuous operation.

In the present embodiment, the protrusions 51, 53, and 52 are arranged so as to overlap the semiconductor elements 31, 33, and 32 when viewed along the z-axis direction. However, the protrusions 51, 53, and 52 do not necessarily have to overlap with the semiconductor elements 31, 33, and 32, respectively, when viewed along the z-axis direction. Further, in the present embodiment, the same number of protrusions 51, 53, 52 as the number of semiconductor elements 31, 33, 32 are provided, but the number of semiconductor elements and the number of protrusions may be different. ..

As described above, the servo amplifier 100 according to the present embodiment includes a circuit board 21, at least one semiconductor element 31 and 32, and a heat sink 40. The semiconductor elements 31 and 32 are mounted on one surface of the circuit board 21. The heat sink 40 is arranged on the other surface of the circuit board 21 and is configured to dissipate heat to the air flowing along the x-axis direction parallel to the circuit board 21. The heat sink 40 has a base plate 41, a plurality of fins 42, a protrusion 51, and a protrusion 52. The base plate 41 is arranged in parallel with the circuit board 21. Each of the plurality of fins 42 extends from the base plate 41 in a direction away from the circuit board 21 along the z-axis direction intersecting the circuit board 21, and is parallel to the circuit board 21 and orthogonal to the x-axis direction in the y-axis direction. They are arranged in parallel at intervals. The protrusion 51 is formed on at least one fin 42e of the plurality of fins 42 and extends along the z-axis direction. The protrusion 52 is formed on at least one fin 42e of the plurality of fins 42, extends along the z-axis direction, and is arranged downstream of the protrusion 51 in the air flow. The width W1 of each of the protrusion 51 and the protrusion 52 in the y-axis direction is wider than the width W0 of each of the plurality of fins 42 in the y-axis direction. The length L2 of the protrusion 52 in the z-axis direction is longer than the length L1 of the protrusion 51 in the z-axis direction. Here, the x-axis direction is an example of the first direction. The z-axis direction is an example of the second direction. Air is an example of a fluid. The heat sink 40 is an example of a radiator. The protrusion 51 is an example of the first protrusion. The protrusion 52 is an example of the second protrusion. The y-axis direction is an example of the third direction.

In the servo amplifier 100, in order to suppress the temperature rise of the semiconductor elements 31 and 32, it is necessary to reduce the sum of the temperature rise width during continuous operation and the temperature rise width during the subsequent instantaneous high heat generation operation. The temperature rise range during continuous operation mainly depends on the heat dissipation performance of the heat sink 40. Normally, the heat dissipation performance of the heat sink 40 becomes lower toward the downstream side due to the air flow. Therefore, the temperature rise width of the semiconductor elements 31 and 32 and the circuit board 21 during continuous operation tends to be larger on the downstream side. In the above configuration of the present embodiment, since the length L1 of the protrusion 51 is shorter than the length L2 of the protrusion 52, the ventilation resistance by the protrusion 51 arranged on the upstream side of the protrusion 52 Can be suppressed from increasing. As a result, it is possible to suppress a decrease in heat dissipation performance in the downstream portion of the heat sink 40.

On the other hand, the temperature rise range during the instantaneous high heat generation operation depends not only on the heat dissipation performance of the heat sink 40 but also on the heat storage performance of the heat sink 40. In the above configuration, since the length L2 of the protrusion 52 is longer than the length L1 of the protrusion 51, the heat capacity of the downstream portion of the heat sink 40 is relatively larger than that of the upstream portion. growing. Therefore, the heat storage performance of the downstream portion of the heat sink 40 is relatively higher than that of the upstream portion. As a result, the temperature rise width of the semiconductor elements 31, 32 and the circuit board 21 during the instantaneous high heat generation operation can be reduced particularly on the downstream side.

Therefore, according to the above configuration, even in the downstream portion of the semiconductor elements 31 and 32 and the circuit board 21 in which the temperature rise width during continuous operation tends to be large, the temperature rise width during continuous operation and the subsequent instantaneous high heat generation operation It is possible to reduce the sum of the temperature rise and the time. Therefore, it is possible to suppress the temperature rise of the semiconductor elements 31 and 32 and the circuit board 21 while suppressing the expansion of the heat dissipation area of the heat sink 40. Therefore, according to the above configuration, it is possible to suppress the increase in size of the heat sink 40.

Further, in the servo amplifier 100 according to the present embodiment, each of the protrusion 51 and the protrusion 52 has an elliptical shape in a cross section parallel to both the x-axis direction and the y-axis direction. According to this configuration, it is possible to suppress an increase in ventilation resistance due to the provision of the protrusion 51 and the protrusion 52. Therefore, it is possible to suppress the temperature rise of the semiconductor elements 31 and 32 particularly during continuous operation.

Further, in the servo amplifier 100 according to the present embodiment, the semiconductor element 31 and the semiconductor element 32 are mounted on the circuit board 21. When viewed along the z-axis direction, the semiconductor element 31 and the semiconductor element 32 are arranged so as to overlap the protrusion 51 and the protrusion 52, respectively. Here, the semiconductor element 31 is an example of the first semiconductor element. The semiconductor element 32 is an example of the second semiconductor element. According to this configuration, the heat generated by the semiconductor element 31 is mainly stored in the protrusion 51 during the instantaneous high heat generation operation, and the heat generated by the semiconductor element 32 is mainly a protrusion having a heat capacity larger than that of the protrusion 51. Heat is stored in the body 52. Therefore, the temperature rise width of the semiconductor element 32 can be made smaller than the temperature rise width of the semiconductor element 31 during the instantaneous high heat generation operation. Therefore, even in the semiconductor element 32 in which the temperature rise width during continuous operation tends to be large, the sum of the temperature rise width during continuous operation and the temperature rise width during the subsequent instantaneous high heat generation operation can be reduced.

Embodiment 2.
The servo amplifier according to the second embodiment of the present invention will be described. FIG. 6 is a plan view showing a configuration in which the control device unit 20 of the servo amplifier 100 according to the present embodiment is viewed in the + z direction. The servo amplifier 100 according to the present embodiment is different from the first embodiment in that the protrusions 51, 53, and 52 are provided on different fins.

As shown in FIG. 6, the protrusion 52 is provided on the fin 42e located substantially at the center of the heat sink 40 in the y-axis direction. The protrusion 51 is provided on the fin 42 g. The fins 42g are located on the + y side of the fins 42e with the fins 42f interposed therebetween. The protrusion 53 is provided on the fin 42c. The fin 42c is located on the −y side of the fin 42e with the fin 42d interposed therebetween.

The semiconductor elements 31, 33, and 32 are arranged so as to overlap the protrusions 51, 53, and 52, respectively, when viewed along the z-axis direction. The semiconductor element 31 and the protrusion 51 are mainly cooled by the air flowing through the air passage between the fins 42f and the fins 42g and the air flowing through the air passage between the fins 42g and the fins 42h. The semiconductor element 33 and the protrusion 53 are mainly cooled by the air flowing through the air passage between the fins 42b and 42c and the air flowing through the air passage between the fins 42c and 42d. The semiconductor element 32 and the protrusion 52 are mainly cooled by the air flowing through the air passage between the fins 42d and 42e and the air flowing through the air passage between the fins 42e and 42f.

The semiconductor elements 31, 33, and 32 all have a first end portion 21a located at the upstream end of the circuit board 21 in the air flow and a second end portion 21b located at the downstream end of the circuit board 21 in the air flow. It is placed between. The semiconductor element 32 is arranged between the semiconductor element 31 and the second end portion 21b when viewed along the y-axis direction. The semiconductor element 33 is arranged between the semiconductor element 31 and the semiconductor element 32 when viewed along the y-axis direction. On the other hand, when viewed along the x-axis direction, the semiconductor element 32 is arranged between the semiconductor element 31 and the semiconductor element 33.

As described above, in the servo amplifier 100 according to the present embodiment, the protrusion 51 and the protrusion 52 are formed on different fins among the plurality of fins 42. Here, it is assumed that the semiconductor element 31 and the semiconductor element 32 are arranged so as to overlap the protrusion 51 and the protrusion 52, respectively, when viewed along the z-axis direction. According to this configuration, the amount of heat received per one of the plurality of fins 42 is reduced, so that the cooling performance of the heat sink 40 can be improved both during continuous operation and during instantaneous high heat generation operation. Further, according to the above configuration, since the semiconductor element 32 can be cooled by low-temperature air having a small amount of heat radiated from the semiconductor element 31, the semiconductor element 32 located on the downstream side of the semiconductor element 31 can be efficiently cooled. .. Therefore, the cooling performance of the heat sink 40 can be improved in both the continuous operation and the instantaneous high heat generation operation.

Further, in the servo amplifier 100 according to the present embodiment, the semiconductor element 31, the semiconductor element 32, and the semiconductor element 33 are mounted on the circuit board 21. The air flow direction is from the first end 21a of the circuit board 21 toward the second end 21b. When viewed along the y-axis direction, the semiconductor element 32 is arranged between the semiconductor element 31 and the second end portion 21b. When viewed along the y-axis direction, the semiconductor element 33 is arranged between the semiconductor element 31 and the semiconductor element 32. When viewed along the x-axis direction, the semiconductor element 32 is arranged between the semiconductor element 31 and the semiconductor element 33. Here, the semiconductor element 31 is an example of the first semiconductor element. The semiconductor element 32 is an example of the second semiconductor element. The semiconductor element 33 is an example of a third semiconductor element. According to this configuration, the semiconductor element 32, which tends to have the highest temperature, can be arranged near the center of the heat sink 40 in the y-axis direction. As a result, the average heat transfer distance of the heat generated in the semiconductor element 32 in the heat sink 40 can be reduced, so that the thermal resistance in the heat sink 40 can be reduced. Therefore, the cooling performance of the heat sink 40 can be improved in both the continuous operation and the instantaneous high heat generation operation.

The present invention is not limited to the above embodiment and can be modified in various ways. For example, in the above embodiment, the natural air-cooled heat sink 40 is taken as an example, but the heat sink 40 may be a forced air-cooled heat sink provided with a fan.

Further, in the above embodiment, air is taken as an example of the fluid as the cooling medium, but other fluids such as water and brine can also be used as the fluid as the cooling medium.

Further, the length, shape, and thickness of the plurality of fins 42 do not necessarily have to be the same. For example, the length of the fin 42 forming the protrusions 51, 52, 53 in the z-axis direction is the same length as the length of the protrusions 51, 52, 53, and the length and the protrusions 51, 52, 53 are set to the same length. The length of any of the fins that are not provided may be different.

10 Command unit, 20 Control equipment unit, 21 Circuit board, 21a 1st end, 21b 2nd end, 31, 32, 33 Semiconductor element, 40 Heat sink, 41 Base plate, 42, 42a, 42b, 42c, 42d, 42e, 42f, 42g, 42h, 42i, 42j fin, 43 tip, 51, 52, 53 protrusion, 51a, 51b, 52a, 52b, 53a, 53b protrusion, 100 servo amplifier.

Claims (5)

With the circuit board
With at least one semiconductor element mounted on one surface of the circuit board,
A radiator arranged on the other surface of the circuit board and dissipating heat to a fluid flowing along a first direction parallel to the circuit board.
With
The radiator
A base plate arranged parallel to the circuit board and
A plurality of components extending from the base plate in a direction away from the circuit board along a second direction intersecting with the circuit board, and parallel to the circuit board in a third direction parallel to the circuit board and orthogonal to the first direction at intervals. Fins and
A first protrusion formed on at least one of the plurality of fins and extended along the second direction.
A second protrusion formed on at least one of the plurality of fins, extending along the second direction, and arranged downstream of the first protrusion in the flow of the fluid. Have and
The width of each of the first protrusion and the second protrusion in the third direction is wider than the width of each of the plurality of fins in the third direction.
A servo amplifier in which the length of the second protrusion in the second direction is longer than the length of the first protrusion in the second direction. The servo amplifier according to claim 1, wherein each of the first protrusion and the second protrusion has an elliptical shape in a cross section parallel to both the first direction and the third direction. A first semiconductor element and a second semiconductor element are mounted on the circuit board as the at least one semiconductor element.
Claim 1 or claim 2 in which the first semiconductor element and the second semiconductor element are arranged so as to overlap the first protrusion and the second protrusion, respectively, when viewed along the second direction. The servo amplifier described in. The servo amplifier according to claim 3, wherein the first protrusion and the second protrusion are formed on different fins among the plurality of fins. A first semiconductor element, a second semiconductor element, and a third semiconductor element are mounted on the circuit board as the at least one semiconductor element.
The flow direction of the fluid is a direction from the first end portion to the second end portion of the circuit board.
When viewed along the third direction, the second semiconductor element is arranged between the first semiconductor element and the second end portion.
When viewed along the third direction, the third semiconductor element is arranged between the first semiconductor element and the second semiconductor element.
The servo amplifier according to claim 1 or 2, wherein the second semiconductor element is arranged between the first semiconductor element and the third semiconductor element when viewed along the first direction.

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