JP2012034533A - Motor pump and method of manufacturing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve waterproofness of a motor pump.SOLUTION: The motor pump includes a pump part 1a, a motor part 1b, a lead wire 8 and a substrate 6, etc., and the substrate 6 is embedded in a mold resin together with a part of the lead wire 8 by insert molding. The substrate 6 has a circuit region 61a where an electric circuit is formed on the surface, and the lead wire 8 is connected to a prescribed connection part 65 there. At the boundary face of the part of the circuit region 61a on the substrate 6 and the mold resin, an insulating coating layer 66 bonded more on the side of the substrate 6 than the mold resin is formed.

Description

  The present invention relates to a motor pump in which a substrate is insert-molded in a resin.

  In the case of a motor pump in which the motor and the pump are integrated, it is essential to ensure waterproofness because it is constantly exposed to water, and electrical components such as the board to be mounted are embedded in the resin by insert molding. It is often molded integrally with a housing or the like (for example, Patent Document 1).

  In the motor pump of Patent Document 1, a circuit board is sealed with resin together with a stator, and a plurality of lead wires connected to the circuit board are bound by a bushing and pulled out of the motor pump. And in this motor pump, the waterproofness of a circuit board is improved by devising a bushing.

  Furthermore, it has been shown that if the circuit board is covered with a waterproof film, the waterproofness of the circuit board can be enhanced.

Also, a coating agent that is applied to the surface of a printed circuit board in order to prevent adhesion such as condensation is known (Patent Document 2).
JP 2010-43540 A JP 2002-146266 A

  If the substrate is insert-molded into the mold resin, the substrate can be effectively prevented from being directly exposed to water. However, since a lead wire for connecting to an external power source or the like is connected to the substrate, it cannot be completely isolated from the outside.

  There is no problem as long as the mold resin is firmly attached to the lead wire, etc.For example, by using a motor pump, due to physical action such as thermal contraction difference and vibration due to repeated high and low temperatures, There may be a gap at the interface of the lead wire or the like. Further, there may be a slight gap at the beginning of the interface between the mold resin and the lead wire due to variations in processing conditions.

  Even if a slight gap occurs at these interfaces, the water penetrates into the inside through the interface. If the infiltrated water reaches the substrate, the substrate may be destroyed.

  As in the motor pump of Patent Document 1, it is possible to improve waterproofness by devising a bushing or the like. However, the possibility of a gap still remains, and thus a drastic solution cannot be achieved.

  In that respect, if a coating agent such as that disclosed in Patent Document 2 is applied to the substrate, the substrate can be prevented from being destroyed even if water enters, which is effective.

  Therefore, as a result of an investigation, since conventional coating agents are not expected to be used for insert-molded substrates, an appropriate waterproof effect can be obtained simply by applying them to the substrate and insert-molding them. I found it impossible.

  Therefore, an object of the present invention is to provide a motor pump that can prevent the substrate from being broken even if water enters the inside of the motor pump in which the substrate is embedded in resin.

  The motor pump of the present invention is provided with a pump unit that discharges fluid, a motor unit that drives the pump unit, a wiring that supplies current to the motor unit, and a midway of the wiring, and controls the motor unit. And a control board, and the board is embedded in the mold resin together with a part of the wiring by insert molding.

  The substrate has a circuit region on which an electronic component is mounted, and the wiring is connected to a predetermined connection portion of the circuit region, and at the interface between the portion of the circuit region on the substrate and the mold resin. An insulating coating layer that adheres to the substrate side of the mold resin is formed.

  According to the motor pump having such a configuration, since the substrate is embedded in the mold resin together with a part of the wiring drawn to the outside, the electrical circuit formed on the surface of the substrate is prevented from being directly exposed to water. Can do. Furthermore, since an insulating coating layer that adheres to the substrate side of the mold resin is formed at the interface between the circuit region portion of the substrate on which the electric circuit is formed and the mold resin, one of the substrate and the wiring is formed. Even if the part is peeled off from the mold resin and a gap is formed along these interfaces, the coating layer adheres to the substrate side.

  Therefore, even if the water that has entered through the gap reaches the substrate, the electrical circuit of the substrate is covered with the coating layer, so that the electrical circuit can be prevented from being damaged.

  In this case, it is preferable that the coating layer has a first region having a relatively small thickness and a second region having a relatively large thickness, and the connecting portion is positioned in the range of the second region.

  Since the concavity and convexity of the connecting portion is structurally large, when forming the coating layer, a gap is likely to be formed due to the entrapment of bubbles or insufficient coating of the coating agent. On the other hand, if the thickness of the coating layer in the connection portion is increased, even if such a gap is formed, it is difficult to form a gap that penetrates the coating layer, so that it is possible to prevent the substrate from being exposed from the coating layer. it can.

  In addition, for the substrate, the coating layer can be firmly adhered using the unevenness of the substrate surface, and for the mold resin, the entire surface of the substrate can be smoothed. The flow of the resin can be stabilized and the molding can be facilitated. By increasing only the necessary thickness of the coating layer, the total amount of the coating layer can be reduced and the material cost can be suppressed.

  In the manufacture of such a motor pump, for example, an application step of applying a liquid coating agent to a portion of the circuit region of the substrate and curing the coating agent by volatilizing the solvent for at least 5 hours or more. A drying step, and an insert molding step in which the substrate is embedded in the mold resin together with a part of the wiring. In the coating step, the viscosity of the coating agent to be applied is set within a range of 200 to 500 mPa · s. The manufacturing method currently used can be used.

  By setting the viscosity of the coating agent at the time of application in the range of 200 to 500 mPa · s, it is possible to form a coating layer in an appropriate form without gaps. In the case of drying at room temperature, drying is performed for about 24 hours, or in the case of forced drying, the temperature is increased and drying is performed for 5 hours or more, so that the solvent having a high boiling point is stably removed. Therefore, it is possible to prevent a gap from being formed in the coating layer due to the generation of bubbles during insert molding, and a uniform coating layer can be formed.

  In the application step, it is preferable to use a dispenser for applying the coating agent.

  If it is a dispenser, the coating agent can be applied accurately and quantitatively, so that a stable and highly accurate coating layer can be formed, especially for forming the first region and the second region having different thicknesses. Is preferred.

  Furthermore, in the insert molding step, it is preferable to set the molding temperature to 150 ° C. or lower. By doing so, it is possible to prevent destruction of electronic components and alteration of the substrate and coating layer, and it is possible to manufacture a motor pump with excellent quality.

  As described above, according to the motor pump of the present invention, the substrate is covered with the coating agent even if a gap occurs at the interface between the wiring and the mold resin and water enters the inside of the motor pump. Therefore, destruction of the substrate can be prevented, and durability and reliability of the motor pump can be improved.

It is a schematic side view of the motor pump of the present embodiment, a part of which is shown in cross section. It is a top view of the motor pump seen from the arrow I direction of FIG. It is a schematic bottom view showing the part of a board | substrate. It is a schematic sectional drawing of the part shown by arrow II in FIG. It is a schematic sectional drawing of the part shown by the arrow III in FIG.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. However, the following description is merely illustrative in nature and does not limit the present invention, its application, or its use.

<Motor pump>
1 and 2 show a motor pump 1 of the present embodiment. In this motor pump 1, a pump (centrifugal pump) and a motor are integrally assembled, and a casing 2, an impeller assembly 3, a rotor 4, a stator 5, a substrate 6, a lead wire 8 (wiring), a pump chamber 9, etc. It has. Among these members, a pump portion 1 a that discharges water (fluid) is constituted by the pump chamber 9 and the impeller assembly 3, and a motor portion 1 b that drives the pump portion 1 a is constituted by the rotor 4 and the stator 5.

  The casing 2 is composed of a first casing 2a on the pump part 1a side that is abutted and fixed integrally, and a second casing 2b on the motor part 1b side. The first casing 2a and the second casing 2b are both synthetic resin injection molded products. The second casing 2b is attached to a frame 67 in which the stator 5, the substrate 6 and the like are embedded by insert molding.

  A pump chamber 9 and a rotor chamber connected to the pump chamber 9 are defined in the casing 2. Specifically, the pump chamber 9 is partitioned by a disk-like lower wall 9a and upper wall 9b, and a cylindrical peripheral wall 9c continuous around the lower wall 9a and the upper wall 9b. The rotor chamber is partitioned by a cylindrical cylindrical wall 10a whose one end is connected to a circular opening that is largely open at the center of the lower wall 9a, and a bottom wall 10b that closes the other end of the cylindrical wall 10a.

  A water supply port 11 for receiving water into the pump chamber 9 is opened at the center of the upper wall 9b, and a water supply pipe 12 is formed so as to extend from the water supply port 11 in the normal direction of the upper wall 9b. One discharge port 13 is formed in the peripheral wall 9c, and a discharge pipe 14 is formed so as to extend in the tangential direction of the peripheral wall 9c therefrom.

  An impeller assembly 3 is disposed inside the pump chamber 9. The impeller assembly 3 includes an annular impeller 3a and a shroud 3b facing each other, and a plurality of blades 3c, 3c,. A central opening of the shroud 3 b facing the upper wall 9 b faces the water supply port 11. On the other hand, the rotor 4 is coupled to the lower wall 9a side of the impeller 3a.

  The rotor 4 is housed in the rotor chamber at the center of the second casing 2 b and has a cylindrical rotor base 41 and a magnet 42 attached to the outer peripheral surface of the rotor base 41. The magnet 42 is generally a plastic magnet, but may be a sintered magnet. In the magnet 42, N poles and S poles are alternately arranged in the circumferential direction.

  In this embodiment, the impeller 3a, the rotor 4, and the blade 3c are integrally formed, and the impeller 3a and the shroud 3b are fixed by ultrasonic welding or the like. A cylindrical spindle 43 is arranged in the casing 2 so that the rotation axis A coincides. The rotor base 41 is rotatably supported around the spindle 43 via a cylindrical bearing 44 in which the spindle 43 is inserted. The upper and lower end surfaces of the bearing 44 are slidably supported by the casing 2 via annular thrust washers 45, 45, respectively.

  The stator 5 is a composite member such as a cylindrical stator core 51, an insulator 52, and a copper wire disposed around the rotor 4, and is embedded in a frame 67. The inner peripheral surface of the stator 5 is opposed to the outer peripheral surface of the rotor 4 with a slight gap. The stator 5 is provided with a stator core 51, an insulator 52, a plurality of coils 53, 53,.

  The stator core 51 is a cylindrical block-like member in which a plurality of electromagnetic steel plates are laminated, and has a plurality of teeth portions extending radially (not shown). A plurality of coils 53, 53,... Are formed by winding conductive wires around these teeth portions via an insulating insulator 52. In order to supply a current to the coils 53, 53,..., Three conductive wire ends 7, 7, 7 are led out from the stator 5. These end portions 7, 7, and 7 are connected to a substrate 6 that drives and controls the motor portion 1b via three binding pins 54, 54, and 54 protruding from the insulator 52 (see FIG. 4).

  FIG. 3 shows the substrate 6. The substrate 6 has a plate-like base 61 and electronic parts 62 such as capacitors and ICs assembled on the surface of the base 61. These electronic components 62 are connected to each other by circuit wiring 63 made of a conductive thin film patterned on the surface of the base 61 to form an electronic circuit (the area where the electronic circuit is formed is called a circuit area 61a). .

  In the present embodiment, the circuit region 61 a is formed on both surfaces of the substrate 6. The circuit area 61a is provided with a first connection portion for connecting the binding pins 54, 54, 54 and second connection portions 65, 65,... For connecting the lead wires 8, 8,. It has been. The lead wires 8, 8,... Are connected to an external power source or the like, and current is supplied to the motor unit 1b through the lead wires 8, 8,. These binding pins 54, 54, 54 and the lead wires 8, 8,... Are connected to the first connection portion and the second connection portions 65, 65,.

  Similarly to the stator 5, the substrate 6 is also embedded in the frame 67 by insert molding. The ends of the binding pins 54, 54, 54 and the lead wires 8, 8,... Are also embedded in the frame 67. The lead wires 8, 8,... Are bound by the bushing 15 at the outer surface portion of the frame 67 and pulled out of the frame 67 (see FIG. 2). In this way, the substrate 6 and the like are embedded in the mold resin constituting the frame 67 (also simply referred to as the frame 67), thereby preventing the substrate 6 from being directly exposed to water.

  However, even if the substrate 6 is insert-molded, a gap may be generated at the interface between the substrate 6 or the lead wire 8 and the frame 67. For example, since the lead wire 8 and the like and the frame 67 are usually made of different materials, they may be affected by a difference in thermal shrinkage due to a temperature change, and an external force such as pump vibration also acts. In addition, there may be a gap at the interface from the beginning due to variations in molding. If a gap occurs at these interfaces and the gap leads to the outside, water may enter the substrate 6 and reach the substrate 6 or the like, and the motor pump 1 may be damaged.

  If the bushing 15 or the like is devised, the waterproof property can be improved, but there is still a possibility that a gap will be generated, so that it does not lead to a radical solution. Therefore, in this motor pump 1, a coating layer 66 is further formed on the surface of the substrate 6 so that the substrate 6 can be prevented from being damaged even if a gap occurs and water enters the inside.

  4 and 5 schematically show a cross section of the substrate 6 embedded in the frame 67. FIG. As shown in these drawings, a coating layer 66 is formed between the substrate 6 and the frame 67. The coating layer 66 is formed on at least the circuit region 61 a portion of the substrate 6 on the surface of the substrate 6.

  The coating layer 66 has a first region 66a having a relatively small thickness and a second region 66b (shown by dots in FIG. 3) having a relatively large thickness.

  That is, the circuit region 61a includes a region having a large surface irregularity such as a portion where the connecting portion 65 of the lead wire 8 and the electronic component 62 are provided, and a portion where the circuit wiring 63 is provided and the base 61. There are regions with small surface irregularities such as exposed portions. In the portion with large irregularities, a gap is easily formed due to the entrapment of bubbles during the formation of the coating layer 66 or insufficient coating of the coating agent. As a result, the substrate 6 may be exposed through the coating layer 66. Therefore, by increasing the thickness of the coating layer 66, such a gap is less likely to occur (second region 66b).

  Further, the coating layer 66 can be firmly adhered to the substrate 6 by using the unevenness. For the frame 67, the surface of the coating layer 66 can be made smooth over the entire circuit region 61a, so that the mold resin can be stably flowed and can be easily molded. That is, the coating layer 66 can be firmly bonded to the substrate 6 side from the frame 67 structurally.

  Furthermore, by increasing the thickness of the coating layer 66 only in necessary portions, the total amount of the coating layer 66 can be reduced, and the material cost can be suppressed. For example, in the present embodiment, the thickness of the first region 66a is set in a range of 10 to 40 μm, and the thickness of the second region 66b is set in a range of 20 to 50 μm (all are thicknesses after drying).

  The coating layer 66 can be formed by applying a coating agent to the substrate 6 as will be described later. However, since insert molding is performed after application, it is difficult to ensure appropriate waterproofness simply by applying an existing coating agent, and therefore it is necessary to satisfy predetermined conditions. In the case of the present embodiment, the coating layer 66 is formed of a synthetic resin that contains a polyolefin-based resin as a main component and is cured by volatilization of the solvent.

First, the coating agent of this embodiment needs to be excellent in insulation as a precondition. For example, the resistance value is preferably 1.0 × 10 ¹² Ω or more. Next, it is necessary to be excellent in heat resistance. It is because it is heated at the time of insert molding. Although depending on the temperature and time of insert molding, heat resistance is required so that at least the form at the time of application (the first region 66a and the second region 66b) can be maintained after molding. For example, a coating agent mainly composed of an acrylic resin cannot be used because of insufficient heat resistance.

  It is excellent in affinity with the substrate 6 and the lead wires 8 and needs to be firmly bonded to the substrate 6 side rather than the frame 67 after insert molding. This is because when the gap is generated at the interface between the substrate 6 and the frame 67 and the coating layer 66 adheres to the frame 67 side and is peeled off from the substrate 6, the waterproof property of the substrate 6 cannot be secured. For example, if the mold resin contains styrene, a coating agent containing a synthetic resin that chemically reacts with styrene, such as a styrene-butadiene rubber, a methylstyrene resin, or an alicyclic saturated hydrocarbon resin, It cannot be used because it is integrated with the mold resin at the time of insert molding.

  Therefore, the coating agent needs to be composed of a component having high affinity with the substrate 6 and the lead wire 8 and low affinity with the frame 67. Incidentally, the adhesion of the coating layer 66 to the substrate 6 side relative to the frame 67 can be confirmed by the fact that the coating layer 66 is substantially adhered to the substrate 6 side when the substrate 6 is peeled off from the frame 67.

  A coating agent capable of setting the viscosity at the time of application within a range of 200 to 500 mPa · s is preferable.

  In the present embodiment, the viscosity is a value at 25 ° C. because it is applied at room temperature. If the viscosity is too low, the coating agent spreads on the base 61, and the coating layer 66 having a desired thickness cannot be stably formed. On the other hand, if the viscosity is too high, bubbles are likely to be involved, the fluidity of the coating agent is deteriorated, and a gap may be formed between the electronic component 62 and the like.

  The following Table 1 shows the test results compared by viscosity using various coating agents (A to E).

  The viscosity shown in the table indicates the viscosity at the time of coating. The C and D coating agents were maintained in the form at the time of application even after insert molding, and the coating agent penetrated well and no formation of gaps was observed. On the other hand, A, B, and E coating agents were inferior to C and D coating agents in terms of form retention and adhesion. Therefore, when the coating agent is applied, the coating layer 66 can be stably formed with high accuracy by setting the viscosity within the range of 200 to 500 mPa · s.

<Manufacturing method of motor pump>
Next, the manufacturing method of the motor pump 1 of this embodiment is demonstrated. This manufacturing method includes an application process, a drying process, an insert molding process, and the like.

(Coating process)
In this step, the coating agent is applied to the circuit region 61a of the substrate 6 where the lead wire 8 is soldered to the connection portion 65 by discharging a liquid coating agent from the nozzle using a dispenser. Application is performed at room temperature (about 25 ° C.). The coating amount per unit area can be adjusted by the extrusion pressure from the nozzle and the moving speed of the nozzle. By using a dispenser for application, the first region 66a and the second region 66b can be formed with high accuracy. The coating agent is previously diluted with a solvent and adjusted to a predetermined viscosity.

(Drying process)
In this step, the coating agent is cured by volatilizing the solvent. Usually, in the case of this kind of coating agent, if it is about 50-70 degreeC, it can be hardened in 0.5 to 1 hour. However, in this embodiment, it is made to dry excessively (overdrying) at 50-70 degreeC for at least 5 hours or more (for example, 8 hours). Since the diluted coating agent usually contains a high boiling point solvent having a boiling point of 100 ° C. or higher (for example, methylcyclohexane, ethylcyclohexane, etc.), if such a solvent remains, insert molding is performed. At this time, gasification may occur and bubbles may be formed, resulting in a gap in the coating layer 66. On the other hand, since the solvent having a high boiling point can be removed by overdrying, the formation of bubbles is suppressed, and a uniform coating layer 66 without a gap can be formed.

(Insert molding process)
In this step, the frame 67 is formed by embedding the substrate 6, part of the lead wires 8, the stator 5, and the like in a mold resin made of a thermosetting resin by insert molding. Since the basic content of insert molding is the same as that of the conventional method, description thereof is omitted. However, the molding temperature is preferably set to 150 ° C. or lower. This is because if it exceeds 150 ° C., the substrate 6 or the like or the coating agent may be thermally denatured. The mold clamping time is about 3 minutes, and the holding time after filling is about 30 to 60 seconds although it depends on the material and shape of the mold resin.

  After the frame 67 is formed, the second casing 2b is inserted into the frame 67, the rotor 4 integrated with the spindle 43 and the impeller assembly 3 is assembled, and the first casing 2a and the frame 67 are fastened with screws. That's fine.

  According to the motor pump 1 of the present embodiment, the coating layer 66 that is more firmly bonded to the substrate 6 than the frame 67 is formed at the interface between the insert-molded substrate 6 and the frame 67. Even if a gap is generated, the coating layer 66 adheres to the substrate 6 side. Therefore, even if water enters the gap, the circuit region 61a is covered with the coating layer 66, so that waterproofness can be ensured and damage to the motor pump 1 can be prevented.

  In addition, the motor pump 1 etc. concerning this invention are not limited to embodiment mentioned above, The other various structure is included.

  In the above-described embodiment, the substrate 6 is insert-molded into the frame 67, and the second casing 2b is inserted into the frame 67. However, the present invention is not limited to this, for example, the second casing 2b is formed together when forming the frame 67. Insert molding may be performed.

  Alternatively, the first region 66a and the second region 66b having different thicknesses may be formed by performing application a plurality of times when forming the coating layer 66 and changing the number of times of application. The coating layer 66 may have a region having a thickness different from those of the first region 66a and the second region 66b.

  For example, it can be used for household appliances used around water such as dishwashers and washing machines. It can also be used for air conditioners where condensation is likely to occur.

DESCRIPTION OF SYMBOLS 1 Motor pump 1a Pump part 1b Motor part 2 Casing 3 Impeller assembly 4 Rotor 5 Stator 6 Substrate 7 End part 8 of conductive wire Lead wire (wiring)
9 pump chamber 61a circuit area 65 second connection portion 66 coating layer 66a first area 66b second area 67 frame

Claims (5)

A pump for discharging fluid;
A motor unit for driving the pump unit;
Wiring for supplying current to the motor unit;
A control board provided in the middle of the wiring and for controlling the motor unit;
A motor pump in which the substrate is embedded in a mold resin together with a part of the wiring by insert molding,
The substrate has a circuit area on which electronic components are mounted,
The wiring is connected to a predetermined connection portion of the circuit area,
A motor pump, wherein an insulating coating layer that adheres to the substrate side of the mold resin is formed at an interface between the circuit region portion of the substrate and the mold resin. The motor pump according to claim 1,
The coating layer has a first region having a relatively small thickness and a second region having a relatively large thickness,
The motor pump in which the connecting portion is located in the range of the second region. It is a manufacturing method of the motor pump according to claim 1 or 2,
An application step of applying a liquid coating agent to a portion of the circuit area of the substrate;
A drying step of curing the coating agent by volatilizing the solvent for at least 5 hours;
An insert molding step of embedding the substrate in the mold resin together with a part of the wiring;
Including
The manufacturing method in which the viscosity of the coating agent to be applied is set in a range of 200 to 500 mPa · s in the application step. In the manufacturing method of Claim 3,
In the coating step, the coating agent is applied using a dispenser. In the manufacturing method of Claim 3 or Claim 4,
The manufacturing method in which the molding temperature is set to 150 ° C. or lower in the insert molding step.

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