JP2008092694A - Switching power supply and electric valve actuator - Google Patents

Abstract

Common mode noise generated in a switching transformer can be efficiently reduced, a Y capacitor can be disposed without increasing the substrate area of a switching power supply, and even if vibration occurs due to cavitation or the like A switching power supply capable of preventing a Y capacitor from being removed from above and an electric valve actuator using the same.
In a switching power source 33 that converts an AC power source into a DC power source, a switching transformer 50 that performs voltage conversion by insulating a wiring 64 on the input side A from a wiring 65 on the output side B, and a wiring 64 on the input side A A Y capacitor 62 mounted between the output side B wiring 65 is provided on the wiring substrate 33 a, and the Y capacitor 62 is disposed between the substrate surface of the wiring substrate 33 a and the switching transformer 50.
[Selection] Figure 5

Description

  The present invention relates to a switching power supply and an electric valve actuator, and more particularly to a switching power supply in which a Y capacitor is mounted between a primary side and a secondary side of a switching transformer and an electric valve actuator using the same.

  For example, electric valve actuators are known as devices that control the flow of cold water, hot water, high-temperature steam, etc. flowing in air-conditioning piping by opening and closing a ball valve or butterfly valve mounted on the piping by rotating a motor or the like. (See, for example, Patent Documents 1 to 3).

  As a power source for the electric valve actuator, a switching power source that has been widely used as a power source for converting an AC power source into a DC power source in various electronic devices has been often used. In a switching power supply, in order to prevent electric shock, a wiring pattern on a substrate is divided and insulated, and voltage conversion is performed by connecting them with a switching transformer.

However, in such a switching power supply, noise, that is, common mode noise is usually generated in the switching transformer. In order to reduce this noise, a Y capacitor called a Y capacitor is generally mounted between the primary side and the secondary side of the switching transformer (see, for example, Patent Documents 4 to 6). .
JP 2006-112501 A JP 2006-112508 A JP 2006-115610 A JP-A-11-266530 JP 2000-244271 A JP 2001-238439 A

  However, in order to mount such a Y capacitor on the substrate, when the wiring pattern is routed on the substrate, if the wiring pattern is lengthened and the wiring pattern is thinned to prevent interference with other wiring patterns, the wiring pattern As a result, the impedance of the Y capacitor including the wiring pattern increases, and the secondary side noise of the switching transformer hardly flows to the primary side. In addition, since the impedance increases depending on the frequency, particularly harmonic components of noise do not escape to the primary side of the switching transformer.

  Further, when the impedance becomes high, the wiring pattern itself can easily emit a radio wave as an antenna, which may be a noise generation source. Therefore, it is required to make the wiring pattern of the Y capacitor as short as possible and as wide as possible.

  On the other hand, for example, when an electric valve actuator is used in an air conditioning facility, the space part in which the air conditioning facility can be used in the building is limited to a very narrow space due to a demand for a wide floor in the building or the like. Therefore, it is required to further reduce the size of the electric valve actuator.

  In such a case, it cannot be expected that the wiring board of the switching power supply of the electric valve actuator will be enlarged to provide a Y capacitor mounting part, and at least the current board area or a smaller board area is limited. In this case, the above-described problem appears remarkably because a Y capacitor must be arranged.

  In addition, when switching power supplies are used for electric valve actuators, as a particular problem, fine bubbles are generated by cavitation when cold water or hot water flowing in the piping passes through ball valves or butterfly valves installed in the piping. To do. At that time, vibration with a low frequency of about 50 to 150 Hz is generated in the entire electric valve actuator through the valve. Similar vibrations occur when steam flows through the piping.

  For this reason, the Y capacitor mounted so as to stand on the wiring board of the switching power supply vibrates due to this low frequency vibration, and the foot portion breaks due to metal fatigue, which is not used for noise reduction. There was a problem of disappearing.

  The present invention has been made in view of the above circumstances, and an object thereof is to provide a switching power supply capable of efficiently reducing common mode noise generated in a switching transformer and an electric valve actuator using the same. . Further, a Y-capacitor can be arranged without increasing the substrate area of the switching power supply, and a switching power supply capable of preventing the Y-capacitor from coming off from the substrate even if vibration occurs due to cavitation or the like, and an electric motor using the same An object is to provide a valve actuator.

In order to solve the above problem, the invention according to claim 1
In switching power supply that converts AC power to DC power,
A switching transformer that performs voltage conversion by insulating the wiring on the input side and the wiring on the output side;
A Y capacitor mounted between the input side wiring and the output side wiring is provided on a wiring board,
The Y capacitor is disposed between a substrate surface of the wiring board and the switching transformer.

  According to the first aspect of the present invention, the common mode noise generated on the secondary side of the switching transformer, that is, on the output side of the circuit via the Y capacitor disposed between the substrate surface of the wiring board and the switching transformer is primary. Back to the input side of the circuit.

  According to a second aspect of the present invention, in the switching power supply according to the first aspect, the Y capacitor is sandwiched between a resin bobbin of the switching transformer and the substrate surface.

  According to the second aspect of the invention, the electric valve actuator and the switching power supply may vibrate due to, for example, cavitation and the wiring board of the switching power supply may vibrate. However, the Y capacitor is replaced with the resin bobbin of the switching transformer and the wiring board. If it is configured to be held between the substrate surface and the Y capacitor, it is possible to prevent the Y capacitor from swinging relative to the wiring substrate or the like.

  According to a third aspect of the present invention, in the switching power supply according to the first or second aspect, the input-side wiring and the output-side wiring on which the Y capacitor is mounted are other wirings on the wiring board. It is characterized by being formed wider.

  According to the third aspect of the present invention, the Y capacitor generates common mode noise generated on the output side of the circuit by connecting the input side wiring and the output side wiring which are formed wide and reduced in impedance. Return to the input side.

  The invention according to claim 4 is an electric valve actuator, wherein the switching power supply according to any one of claims 1 to 3 is used, and the switching power supply converts the AC power supply into a DC power supply. It is characterized by doing.

  According to the invention described in claim 4, when the switching power supply described in each of the above claims is applied to an electric valve actuator, all useful functions of the switching power supply are effectively exhibited in the electric valve actuator.

  According to the first aspect of the present invention, since the Y capacitor is disposed between the substrate surface of the wiring board and the switching transformer, the wiring pattern of the Y capacitor can be formed at the shortest distance.

  Therefore, the L component of the impedance of the wiring pattern of the Y capacitor is greatly reduced to reduce the impedance, and harmonic common mode noise generated on the secondary side of the switching transformer via the Y capacitor is transferred to the primary side of the switching transformer. It can be returned efficiently. In this way, according to the switching power supply of the first aspect, it is possible to efficiently reduce common mode noise generated in the switching transformer as shown in FIG. 9A described later.

  Further, if the Y capacitor is disposed between the board surface of the wiring board and the switching transformer, the switching transformer may be separated from the wiring board of the switching power source by an amount that can accommodate the Y capacitor. Therefore, it is not necessary to newly provide a Y capacitor mounting portion, and the Y capacitor can be arranged without increasing the substrate area of the switching power supply. For this reason, at least the current substrate area of the switching power supply can be maintained, or the switching power supply can be further downsized.

  According to the second aspect of the present invention, if the Y capacitor is configured to be sandwiched between the resin bobbin of the switching transformer and the substrate surface of the wiring board, the Y capacitor will be in relation to the wiring board or the like even if cavitation occurs. Relative rocking is prevented. Therefore, in addition to the effects of the present invention, it is possible to effectively prevent the Y capacitor from swinging on the wiring board and causing its legs to become metal fatigue and disengage from the wiring board.

  Further, if an adhesive is injected and fixed between the resin bobbin of the switching transformer and the Y capacitor, it is possible to more reliably prevent the Y capacitor from being detached from the wiring board.

  According to the third aspect of the present invention, the input-side wiring and the output-side wiring are formed wider than the other wirings on the wiring board, so that the R component of the impedance of the wiring pattern is reduced and the impedance is reduced. Is further reduced. Therefore, harmonic common mode noise can be more efficiently transmitted from the secondary side to the primary side of the switching transformer via the Y capacitor, and the effects of the above inventions can be more effectively exhibited. It becomes possible to more efficiently reduce common mode noise generated in the transformer.

  According to the invention described in claim 4, when the switching power supply described in each of the claims is applied to the electric valve actuator, all useful functions and effects of the switching power supply are effectively exhibited in the electric valve actuator. Further, since the electric valve actuator can be reduced in size, the electric valve actuator according to the present invention can be used in an air conditioning facility in a building or the like, even if the installation location is spatially narrow. If so, it can be installed sufficiently, and the generated noise is reduced.

  Embodiments of a switching power supply and an electric valve actuator according to the present invention will be described below with reference to the drawings.

  First, the configuration of the electric valve actuator according to this embodiment will be described. As shown in FIGS. 1 to 3, the electric valve actuator 1 mainly includes a power supply drive unit 2 and a valve body 3. The electric valve actuator 1 is not necessarily attached to the pipe T so that the valve main body 3 is disposed below the electric drive unit 2, but in the following, the vertical direction in FIGS. The vertical direction will be described. FIG. 3 is a top view of the electric drive unit with the upper cover body removed.

  The power supply drive unit 2 is provided with a substantially casing-type cover body 4 for protecting internal members. The cover body 4 is formed by, for example, screwing the upper cover body 4a to the lower cover body 4b via a gasket 4c. It is fixed by a stopper or the like.

  Inside the cover body 4, an upper support plate 5 and a lower support plate 6 are respectively disposed in the horizontal direction. The lower support plate 6 is fixed so as to be placed on a rib-like support 7 erected from the bottom surface of the cover body 4, and is attached to a cylindrical spacer 8 erected on the lower support plate 6. By fixing the upper support plate 5 via screws 9 or the like, the upper support plate 5 is disposed above the lower support plate 6 by a certain distance. Further, the upper support plate 5 is pressed in a direction toward the inside of the cover body 4 from a rib-shaped pressing body 10 formed on the inner surface of the cover body 4, and is affected by vibration due to cavitation or the like. It comes to be fixed without.

  An electric motor 11 made of a stepping motor or the like whose rotation is controlled by an exciting current is attached to the upper surface side of the upper support plate 5 at one end side inside the cover body 4, and the output shaft 12 of the electric motor 11 is supported by the upper support. It arrange | positions so that the board 5 may be penetrated and the downward direction of the upper support plate 5 may be protruded.

  In a region between the upper support plate 5 and the lower support plate 6 from which the output shaft 12 of the electric motor 11 is projected, a gear mechanism 13 composed of a plurality of gears rotatably supported to mesh with each other is provided. The gear mechanism 13 transmits the output shaft 14 to the gear 15 of the output shaft 14 to the valve body 3 while rotating the output shaft 12 while reducing the rotation of the output shaft 12 of the electric motor 11.

  In the gear mechanism 13, the intermediate gear 13a is biased upward by a spring 13b disposed between the lower support plate 6 and the intermediate gear 13a. The intermediate gear 13a has a clutch rod 16 in sliding contact with the upper surface thereof. The clutch rod 16 passes through the upper support plate 5, and its upper end is inserted into a clutch insertion hole 17 that is suspended from the upper surface of the cover body 4. A clutch button 20 is mounted above the clutch rod 16 via an annular wheel 18 and a spring 19 so as to be movable in the vertical direction. The clutch button 20 is pushed down and the intermediate gear 13a is interposed via the clutch rod 16. By releasing the engagement, the gear mechanism 13 is disconnected from the electric motor 11, and the power supply drive unit 2 can be manually operated.

  The output shaft 14 to the valve body 3 is rotatable to the upper support plate 5 and the lower support plate 6 by an upper bearing 21 and a lower bearing 22 attached to the upper support plate 5 and the lower support plate 6, respectively. It is supported by. Further, an insertion hole 23 of the output shaft 14 is provided above the output shaft 14 of the cover body 4, and the output shaft 14 is inserted into the insertion hole 23, and an upper side 24 thereof is a manual of the output shaft 14. It is the operation unit.

  A stopper pin 25 is erected upward at one end of the upper surface of the gear 15 of the output shaft 14 to the valve body 3, and the upper end of the stopper pin 25 is formed in an arc shape on the upper support plate 5. The hole 26 is loosely fitted. The rotation angle of the output shaft 14 is regulated by the stopper pin 25 loosely fitted in the arc hole 26 in this way. In order to open and close a rotary valve such as a ball valve or a butterfly valve (not shown) provided in the valve body 3, it is necessary that the output shaft 14 can be rotated by 90 ° around it. In the embodiment, the arc hole 26 is formed so that the output shaft 14 can turn 100 ° with a margin of 5 ° in the opening / closing direction of the rotary valve.

  The lower end of the output shaft 14 is inserted through an insertion hole 27 provided at a position corresponding to the lower bearing 22 of the cover body 4, and opens and closes the rotary valve inserted through the support shaft 28 of the valve body 3. It is connected with the opening-and-closing axis | shaft 29 for making it. A valve connection nut 31 is inserted in a predetermined position of the lower surface of the cover body 4 and the lower support plate 6 in order to fix a mounting piece 30 integrally formed with the support shaft 28 of the valve body 3. Are screwed together and the lower surface of the cover body 4 and the attachment piece 30 are fastened together to attach the valve body 3 to the electric drive unit 2.

  In a region between the upper support plate 5 on the upper end side of the output shaft 14 and the upper surface of the cover body 4, the wiring substrate 33 a of the switching power supply 33 is supported by a spacer 34 erected on the upper surface of the upper support plate 5. It is disposed substantially parallel to the upper indicator plate 5. A hole 35 through which the output shaft 14 is inserted is formed in the wiring board 33 a of the switching power supply 33.

  Around the output shaft 14 above the wiring board 33a, an annular magnet 36 divided into S poles and N poles within a range of 180 ° is mounted. On the wiring board 33a inside thereof, the annular magnet 36 is mounted. Is provided with a magnetic element 37 for detecting the magnetism of the annular magnet 36. The magnetic element 37 detects the magnetism of the annular magnet 36 that changes with the opening and closing operations of the rotary valve due to the rotation of the output shaft 14 and controls the information to control means (not shown) that controls the operation of the electric valve actuator 1. Is supposed to send.

  A light emitting member 38 made up of LED (Light Emitting Diode) or the like is mounted on the wiring board 33a. In the present embodiment, two light emitting members 38 each having a different emission color are attached, and any one of them emits light in accordance with the open state or the closed state of the rotary valve of the valve body 3. The light emitted from the light emitting member 38 is transmitted to the entire visual recognition cover 40 through the light guide rib 39 provided on the cover body 4 above the light emitting member 38. It is possible to grasp the situation such as opening and closing of the rotary valve.

  Further, in the present embodiment, on one side surface of the cover body 4, a wire tube port 41 is provided for inserting electric wires such as a power line and a signal line connected to the electric drive unit 2 from the outside. Although omitted in the present embodiment, in order to prevent condensation from occurring in the electric drive unit 2 and the valve body 3 when supplying a low-temperature fluid for cooling and freezing, the electric drive unit 2 and the valve It is also possible to configure the main body 3 to include a heat insulating material, a heater, and the like.

  Next, the configuration of the switching power supply 33 according to the present invention will be described.

  The circuit of the switching power supply 33 according to the present embodiment uses a so-called insulating flyback method. FIG. 4 is a circuit diagram of the switching power supply according to the present embodiment. A switching transformer 50 that insulates the wiring on the input side A from the wiring on the output side B is provided in the approximate center of the circuit. In FIG. 4, the right side of the drawing is the input side A and the left side is the output side B in accordance with the direction of the wiring board 33a of the switching power supply 33 shown in the top view of FIG.

  On the input side A of the circuit, that is, the primary side of the switching transformer 50, an input terminal 51 to which a commercial AC power supply of about 50/60 Hz and about 90 to 240V is input, an X capacitor 52 for reducing normal mode noise, and for reducing common mode noise Common mode choke coil 53, commercial power supply rectifier bridge diode 54, smoothing capacitor 55, switching power supply control IC 56, and the like.

  The switching power supply control IC 56 supplies the switching transformer 50 with a constant DC voltage on the output side B even when the input commercial AC power supply fluctuates within the input range of about 90 to 240 V as described above. Control is performed so that a current subjected to PWM modulation flows.

  On the output side B of the circuit, that is, on the secondary side of the switching transformer 50, a rectifier diode 57, a smoothing capacitor 58, a control reference voltage IC 59, a coil 60, an output terminal 61, and the like are provided.

  Further, the circuit includes a Y capacitor 62 mounted between the input side A and the output side B, that is, the primary side and the secondary side of the switching transformer 50, and a primary side through a light-transmitting insulator (not shown). A photocoupler 63 in which the light receiving element 63a and the secondary side light emitting element 63b are optically coupled is provided.

  Here, although the switching transformer 50 and the Y capacitor 62 are provided on the wiring board 33a, in this embodiment, as shown in FIG. 5, each is mounted on the lower surface side of the wiring board 33a of the switching power supply 33. It has become. In the following FIG. 5 and the like, illustrations of components necessary for explanation and components other than wiring are omitted.

  The switching transformer 50 is configured by winding a primary coil 50b, a primary bias coil 50c, and a secondary coil 50d around an iron core 50a through an insulator, and is arranged at the bottom of the switching transformer 50, that is, on the wiring board 33a side. Is formed with a resin bobbin 50e. Further, the primary bias coil 50c and the secondary coil 50d are connected to the primary side pin 50h and the secondary side pin 50i through the conducting wires 50f and 50g, respectively. The primary bias coil 50c and the secondary coil 50d are respectively connected to the primary bias coil 50c and the secondary coil 50d. A reference potential of 0 V is supplied through the conductive wires 50f and 50g.

  The Y capacitor 62 is disposed between the substrate surface of the wiring board 33a and the resin bobbin 50e of the switching transformer 50. The two legs 62a and 62b of the Y capacitor 62 are pins on the primary side of the switching transformer 50, respectively. 50h and the secondary side pin 50i are connected to the input side A wiring 64 and the output side B wiring 65, respectively.

  In the present embodiment, as shown in FIG. 6, the Y capacitor 62 has its legs 62a, 62b bent at a position close to the wiring board 33a and lying on its side, and its main body portion is in contact with the wiring board 33a. . In addition, the switching transformer 50 and the Y capacitor 62 are arranged on the wiring board 33a so that the main body portion of the Y capacitor 62 in this state is sandwiched between the board surface of the wiring board 33a and the resin bobbin 50e of the switching transformer 50.

  The Y capacitor 62 is not necessarily sandwiched between the substrate surface of the wiring substrate 33a and the resin bobbin 50e of the switching transformer 50. Further, in the present embodiment, the switching transformer 50, the resin bobbin 50e, the Y capacitor 62, the switching power supply control IC not shown in FIGS. 5 and 6, and the like exist in close proximity on the wiring board 33a. By injecting an adhesive into the gap portion so as to ensure the mutual spatial distance and edge distance, they are fixed together by the adhesive.

  At that time, the input-side A wiring 64 and the output-side B wiring 65 on the wiring board 33a have thick wiring patterns as shown in FIG. 7, and in this embodiment, the two wirings 64, 65 are Each is formed wider than the other wiring on the wiring board 33a.

  In the present embodiment, the wiring 64 on the input side A is made of metal which is connected to the ground line 56a of the switching power supply control IC 56 and provided on the lower surface side of the wiring board 33a as shown in FIGS. The heat sink (heat radiating plate) 67 made of metal such as aluminum is attached to the attachment block 66 through the attachment block 66.

  The heat sink 67 is attached to the attachment block 66, and is fastened to the back surface of the switching power supply control IC 56 with a conductive eyelet 68 such as brass or aluminum, and is substantially perpendicular to the lower surface of the peripheral portion of the wiring board 33a. It extends downward. It is also possible to fix with rivets, clips, screws or the like instead of eyelets.

  Next, the operation of the switching power supply 33 and the electric valve actuator 1 according to this embodiment will be described.

  The operation of the electric valve actuator 1 according to the present embodiment is as described in the above configuration, and the description thereof is omitted here.

  The operation of the switching power supply 33 according to this embodiment will be described.

  First, in the circuit diagram shown in FIG. 4, when a commercial AC power supply of 50/60 Hz and 90 to 240 V is applied to the input terminal 51, the AC power supply is an EMI filter composed of an X capacitor 52 and a common mode coil 53. Is converted into a DC power source on the input side A, that is, the primary side of the switching transformer 50 by the commercial power source rectifier bridge diode 54 and the smoothing capacitor 55.

  The primary side DC power supply is connected to the drain of the switching power supply control IC 56 via the switching transformer 50. The switching power supply control IC 56 supplies the switching transformer 50 with a constant DC voltage on the output side B even when the input commercial AC power supply fluctuates within the input range of about 90 to 240 V as described above. A current with PWM modulation is applied.

  A pulsed current of several tens kHz to several hundreds kHz according to the load flows through the primary coil 50b of the switching transformer 50. A pulsed voltage corresponding to the turn ratio with the primary coil is induced in the secondary coil 50d of the switching transformer 50. Thus, the switching transformer 50 not only insulates the wiring on the input side A and the wiring on the output side B of the circuit as described above, but also plays a plurality of roles of storing energy and converting voltage.

  The rectifier diode 57 and the smoothing capacitor 58 provided on the output side B of the circuit, that is, the secondary side of the switching transformer 50 rectify the pulsed voltage induced in the secondary coil 50d of the switching transformer 50 to provide a DC power source. obtain. The coil 60 blocks noise flowing in from the outside of the switching power supply 33 via the output terminal 61.

  The control reference voltage IC 59 is combined with the photocoupler 63 so as to stably output a DC voltage, and transmits a feedback signal to the switching power supply control IC 56 while insulating the input side A and output side B of the circuit.

  As described above, in the switching power supply 33 according to the present embodiment, a constant DC voltage is always supplied from the output terminal 61 even if the commercial AC power applied to the input terminal 51 fluctuates in the input range of 90 to 240 V, for example. Is output.

  On the other hand, the Y capacitor 62 generates harmonic common mode noise superimposed on the pulsed voltage generated on the output side B of the circuit, that is, the secondary side of the switching transformer 50, on the input side A of the circuit, that is, the primary side of the switching transformer 50. return. In this way, the Y capacitor 62 prevents harmful radiation electromagnetic waves from being emitted from the output side B of the circuit to the surroundings.

  The Y capacitor 62 is disposed between the substrate surface of the wiring substrate 33 a and the resin bobbin 50 e of the switching transformer 50. Therefore, the Y capacitor 62 can be connected to the primary side of the switching transformer 50 by the foot 62 a and the wiring 64, and can be connected to the secondary side of the switching transformer 50 by the foot 62 b and the wiring 65. It is possible to keep the pattern within the shortest possible distance.

  As a result, the L component of the impedance of the wiring pattern of the Y capacitor 62 is greatly reduced to reduce the impedance, and harmonic common mode noise generated on the secondary side of the switching transformer 50 via the Y capacitor 62 is reduced to the switching transformer. 50 can be efficiently returned to the primary side.

  If the wirings 64 and 65 to which the legs 62a and 62b of the Y capacitor 62 are connected are formed wider than the other wirings on the wiring board 33a as in this embodiment, the R component of the impedance of the wiring pattern. Therefore, the impedance is further reduced, and the harmonic common mode noise is more efficiently transmitted from the secondary side to the primary side of the switching transformer 50 via the Y capacitor 62.

  In particular, in the present embodiment, the wiring 64 connected to the foot 62a of the Y capacitor 62 is further connected to the heat sink 67 of the switching power supply control IC 56, and as shown in the circuit diagram of FIG. Since the switching current on the primary side of the switching transformer 50 flowing in from the drain and flowing out from the source flows also to the heat sink 67, the impedance of the input side A of the circuit is reduced and the output is reduced because the heat sink 67 has a large area. Harmonic noise generated not only on the side B but also on the input side A can be efficiently transmitted to the EMI filter to reduce radiation noise.

  As described above, according to the switching power supply 33 and the electric valve actuator 1 according to the present embodiment, the Y capacitor 62 is disposed between the substrate surface of the wiring board 33a and the switching transformer 50, so The wiring pattern can be formed at the shortest distance.

  Therefore, the L component of the impedance of the wiring pattern of the Y capacitor 62 is greatly reduced to reduce the impedance, and the harmonic common mode noise generated on the secondary side of the switching transformer 50 through the Y capacitor 62 is reduced to the switching transformer 50. Can be efficiently returned to the primary side. As described above, the switching power supply 33 according to the present embodiment can efficiently reduce common mode noise generated in the switching transformer 50.

  Here, the measurement result of the radiation noise from the switching power supply is shown in FIG. 9A shows the result of the switching power supply according to the present embodiment, and FIG. 9B shows the result of the switching power supply in which the Y capacitor is arranged at a position not between the switching transformer and the substrate surface on the wiring board. Show. In addition, the dashed-dotted line in FIG. 9 represents the conformity standard of the Class B of the radio wave interference voluntary regulation association (VCCI) such as the information processing apparatus regarding the radiation noise level.

  As shown in FIG. 9B, when the Y capacitor 62 is disposed at a position not between the switching transformer 50 and the substrate surface on the wiring board 33a, the switching power supply sufficiently generates harmonic common mode noise. While there is a frequency band that cannot be reduced and exceeds the conformance standard of the class B, as shown in FIG. 9A, in the switching power supply 33 according to the present embodiment, the generated common mode noise is of the class B. It can be seen that the efficiency is effectively reduced to a level far below the conformance standard.

  Further, as in this embodiment, the wiring 64 on the input side A and the wiring 65 on the output side B on which the Y capacitor 62 is mounted are formed wider than the other wirings on the wiring board 33a, so that the wiring pattern The R component of the impedance is also reduced to further reduce the impedance. Therefore, harmonic common mode noise can be more efficiently transmitted from the secondary side to the primary side of the switching transformer 50 via the Y capacitor 62, and the common mode noise generated in the switching transformer 50 can be more efficiently transmitted. It becomes possible to reduce.

  Further, as in this embodiment, the wiring 64 connected to the foot 62a of the Y capacitor 62 is further connected to the heat sink 67 of the switching power supply control IC 56, and the switching transformer 50 flowing out from the source of the switching power supply control IC 56. If the switching current on the primary side is also passed through the heat sink 67, the impedance of the input side A of the circuit is reduced because the heat sink 67 has a large area, and harmonics generated not only on the output side B but also on the input side A. The noise can be efficiently transmitted to the EMI filter to reduce the radiation noise.

  If the Y capacitor 62 is disposed between the substrate surface of the wiring board 33a and the switching transformer 50 as described above, the switching transformer 50 is separated from the wiring board 33a of the switching power supply 33 by an amount that can accommodate the Y capacitor 62. Therefore, it is not necessary to enlarge the wiring substrate 33a and newly provide a mounting portion for the Y capacitor 62, and the Y capacitor 62 can be arranged without increasing the substrate area of the switching power supply 33. Become. Therefore, at least the current substrate area of the switching power supply 33 can be maintained, or the switching power supply 33 can be further downsized.

  At that time, the electric valve actuator 1 and the switching power supply 33 may vibrate due to cavitation or the like, and the wiring board 33a of the switching power supply 33 may vibrate. However, the Y capacitor 62 is replaced with the resin bobbin 50e of the switching transformer 50 and the wiring board 33a. If it is configured to be sandwiched between the substrate surface, it is possible to prevent the Y capacitor 62 from swinging relative to the wiring substrate 33a and the like. Therefore, it is possible to effectively prevent the Y capacitor 62 from swinging on the wiring board 33a and causing the legs 62a and 62b to become metal fatigue and disengage from the wiring board 33a.

  Further, if an adhesive is injected and fixed between the resin bobbin 50e of the switching transformer 50 and the Y capacitor 62, it is possible to more reliably prevent the Y capacitor 62 from being detached from the wiring board 33a.

  If the switching power supply 33 as described above is applied to the electric valve actuator 1, all the effects of the switching power supply 33 are effectively exhibited in the electric valve actuator 1. In addition, since the electric valve actuator 1 can be downsized, the electric valve according to the present embodiment is used even when the installation location is spatially narrow when used in an air conditioner or the like in a building or the like. The actuator 1 can be sufficiently installed, and the generated noise is reduced.

  As in the present embodiment, the heat sink 67 is connected to the primary leg 62a of the Y capacitor 62 so as to be a part of the source terminal circuit of the switching power supply control IC 56, thereby flowing in from the drain of the switching power supply control IC 56. Thus, a part of the switching current on the input side A flowing out from the source can also flow to the heat sink 67.

  Therefore, even if the wiring pattern on the input side A of the circuit becomes a little longer or thinner, the heat sink 67 can function as a wide wiring to prevent an increase in the impedance of the circuit. Therefore, it is possible to efficiently transmit harmonic noise generated on the input side A to the EMI filter to reduce radiation noise. Further, by providing the heat sink 67 upright with respect to the wiring board 33a at the peripheral edge of the wiring board 33a, it is possible to reduce the size of the switching power supply 33 by configuring the circuit three-dimensionally and improving the mounting density. Become.

  In addition, by providing the heat sink 67 upright with respect to the wiring board 33a at the peripheral edge of the wiring board 33a, the heat sink 67 can have a shield function for covering the side surface of the transformer, thereby improving the strength against electrostatic noise.

  Further, by using a brass or aluminum eyelet 68 as a member for fastening the switching power supply control IC 56 and the heat sink 67, the electrical connection can be ensured without being affected by an insulating material such as silicon rubber or silicon oil. In addition, it can be fastened and fixed easily and inexpensively. The heat sink 67 also functions as a heat sink for electrical components such as the switching power supply control IC 56.

  Further, if the heat sink 67 is arranged in the vicinity of the switching transformer 50 at the peripheral portion of the wiring board 33a, the heat sink 67 is connected to the switching transformer 50, the resin bobbin 50e, the Y capacitor 62, the switching power supply control IC 56, etc. It becomes possible to fix together with an adhesive in a state in which the edge surface distance is secured. At that time, if the lead portion, mold portion, etc. of the electrolytic capacitor are simultaneously fixed with an adhesive, they can be prevented from being broken or damaged, and the switching power supply 33 and the electric valve actuator 1 product using the same. As a result, it is possible to improve the reliability and prevent accidents.

It is a front fragmentary sectional view which shows the structure of the electric valve actuator which concerns on this embodiment. FIG. 2 is a partial side sectional view showing a configuration of the electric valve actuator of FIG. 1. It is a top view of the electric drive part in the state which removed the upper cover body of the electric valve actuator of FIG. It is a circuit diagram of the switching power supply concerning this embodiment. It is sectional drawing of the switching transformer and Y capacitor | condenser mounted in the switching power supply which concerns on this embodiment. FIG. 6 is a partial side sectional view of a resin bobbin of the Y capacitor and the switching transformer of FIG. 5. FIG. 6 is a top view of a Y capacitor portion of a wiring board of the switching power supply of FIG. 5. It is a perspective view which shows the heat sink etc. which were attached to the peripheral part of a wiring board. It is a graph which shows the measurement result of the radiation noise from a switching power supply, (A) shows the result of the switching power supply which concerns on this embodiment, (B) shows the result of the switching power supply which changed arrangement | positioning of the Y capacitor.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Electric valve actuator 33 Switching power supply 33a Wiring board 50 Switching transformer 50e Resin bobbin 62 Y capacitor 64 Input side wiring 65 Output side wiring A Input side B Output side

Claims (4)

In switching power supply that converts AC power to DC power,
A switching transformer that performs voltage conversion by insulating the wiring on the input side and the wiring on the output side;
A Y capacitor mounted between the input side wiring and the output side wiring is provided on a wiring board,
The switching power supply, wherein the Y capacitor is disposed between a substrate surface of the wiring board and the switching transformer.   The switching power supply according to claim 1, wherein the Y capacitor is sandwiched between a resin bobbin of the switching transformer and the substrate surface.   3. The input side wiring and the output side wiring on which the Y capacitor is mounted are formed wider than other wirings on the wiring board. Switching power supply.   An electric valve actuator using the switching power supply according to any one of claims 1 to 3, wherein the switching power supply converts an AC power supply into a DC power supply.

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