Patent Description:
Conventionally, as a so-called electric valve for opening and closing a valve electrically, those provided with a power transmission device for decelerating the rotational force of a stepping motor with a speed reduction device or directly transmitting the rotational force to a screw mechanism are known (see Patent Document <NUM>.

Such a stepping motor for an electric valve is housed in a sealed state in a housing to prevent moisture, foreign matter, and the like from adhering to a circuit board or the like.

[Patent Document <NUM>] Japanese Unexamined Patent Application Publication No.<CIT>.

<CIT> describes a device unit for a throttle body, wherein the device unit has a device block detachable or undetachable installed on the throttle body in which a throttle valve for opening and closing a bore is installed and having at least one modularized device part, and also has the device cover for covering the device part of the device block. A ridge facing the entire periphery of an outer peripheral part of the device cover is formed on the device block. The device cover is resin-welded to the device block, with the forward end of the ridge used as the portion to be welded to the device block. The device block having the ridge is formed of an absorptive resin material with high laser beam absorptance. The device cover is formed of a light transmissive resin material with high laser beam transmittance. The device cover is resin-welded to the device block by a laser beam.

<CIT> describes a motor-operated valve including a valve element, a driver moving the valve element along a first axis, a rotating shaft rotating the driver around the first axis, a permanent magnet member, and an angle sensor. The permanent magnet member is disposed on the rotating shaft and is rotated together with the rotating shaft. The angle sensor detects a rotation angle of a permanent magnet of the permanent magnet member. The angle sensor is arranged over the permanent magnet.

<CIT> describes a motor-operated valve including a driving unit including a rotor and a stator, a feed screw mechanism, and a valve main body unit. In order to remove backlash intrinsic in the feed screw mechanism, a coil spring that urges a valve body in a direction away from a valve seat is arranged in a valve chamber. A spring bearing that forms a housing, in which the coil spring is housed, in the valve chamber is provided. Therefore, the large valve chamber is secured in the valve main body unit and passing sound is reduced when a fluid passes the motor-operated valve. Contact surfaces of the valve body and the coil spring can be aligning curved surfaces that absorb a bend of the coil spring.

<CIT> describes a water valve, guide tube for a water valve, and an associated method of manufacturing a water valve. The water valve includes a housing, and the guide tube is installed on the housing via laser welding. The guide tube and housing each provide axially facing mating surfaces which abut one another in a pre-bonded configuration. In a post-bonded configuration, a laser weld joint is formed at the interface between the mating surfaces. The joint forms a portion of an outer periphery of the housing.

<CIT> describes a fluid control electromagnetic valve including a fixed core, a movable valving element, a resin body, a valve seat member, a first sealing member, and a second sealing member. The valve seat member is formed from a material having a smaller linear expansion coefficient than the resin body. The first sealing member is accommodated in the resin body in an elastic compression state to seal a fluid passage and is positioned around the fixed core. The second sealing member is accommodated in the resin body in an elastic compression state to seal the fluid passage. The valve seat member is clamped between the second sealing member and the first sealing member in an axial direction. Elastic restoring force applied by the second sealing member to the valve seat member is larger than elastic restoring force applied by the first sealing member to the valve seat member.

<CIT> describes a filter device equipped with a filter which can be welded continuously on the inner wall of a fluid passage made of a permeable resin material and an absorbing resin material. A housing is formed of a valve sheet made of a permeable resin material which allows laser beam to permeate and a valve case made of an absorbing resin material which absorbs laser beam. A fluid passage is constituted of inner walls of the valve case and the valve sheet. In the fluid passage, the filter unit is disposed. In the filter unit, a filter part is supported by a filter support material. The filter support material is laser welded at the inner wall of the fluid passage. Of the filter support material, the part to be bonded to the inner wall of the fluid passage made from the permeable resin is made from an absorbing resin material, and the other part bonded to the inner wall of the fluid passage made of an absorbing resin is made of a permeable resin material.

Here, in the electric valve disclosed in Patent Document <NUM>, a housing member is formed by a tube-shaped member and a cover member covering the tube-shaped member, and in order to further ensure the sealing properties in the housing member, a packing is disposed between the tube-shaped member and the cover member. For this reason, in addition to the increase in manufacturing man-hours due to the increase in the number of assembled parts, there is a problem that the housing member becomes large due to the provision of a peripheral groove for arranging the packing or a snap-fit structure for fixing the tube-shaped member and the cover member to each other.

Accordingly, an object of the present invention is to provide an electric valve that can be further miniaturized while reducing manufacturing man-hours.

In order to achieve the above object, an electric valve according to the present invention as reflected by claim <NUM> includes a motor including a rotor member and a stator member for applying a rotational force to the rotor member; a power transmission mechanism for converting rotational movement of the rotor member into axial movement of a valve body; a housing for accommodating the motor and the power transmission mechanism; and a base member connected to the housing and provided with a valve seat to which the valve body is separated or seated, wherein: the housing includes: a heat generation portion formed of a first material, and a heat receiving portion formed of a second material and bonded to the heat generation portion, and a laser light transmittance in the first material is lower than a laser light transmittance in the second material.

According to the present invention, it is possible to provide an electric valve that can be further miniaturized while reducing manufacturing man-hours.

Hereinafter, an electric valve according to the embodiments of the present invention will be described with reference to the drawings. It should be noted that, in the present specification, the direction from the rotor to the valve seat is defined as the downward direction, and the opposite direction thereof is defined as the upward direction.

Referring to <FIG>, a description will be provided of the electric valve <NUM> according to the first embodiment. <FIG> is a schematic sectional view illustrating an overview of an electric valve <NUM> according to the first embodiment.

The electric valve <NUM> includes, accommodated in the housing <NUM>, a driver <NUM>, a rotary shaft <NUM>, a stepping motor <NUM> for transmitting a rotational force to the rotary shaft <NUM>, a power transmission mechanism <NUM> for converting and transmitting the rotary motion of the rotary shaft <NUM> into axial motion of the valve body <NUM>, a permanent magnet <NUM> mounted so as to rotate together with the rotary shaft <NUM>, and an angle sensor <NUM> for detecting the rotation angle of the permanent magnet <NUM>, and a valve body <NUM> and a valve seat <NUM> accommodated in the lower base member <NUM>.

The lower base member <NUM> includes a first flow path <NUM> and a second flow path <NUM>. When the valve body <NUM> is separated from valve seat <NUM>, in other words, when the valve body <NUM> is in an upper position, the fluid flows into the valve chamber <NUM> through the first flow path <NUM> and is discharged through the second flow path <NUM>. In contrast, when the valve body <NUM> is seated on the valve seat <NUM>, in other words, when the valve body <NUM> is in a lower position, the first flow path <NUM> and the second flow path <NUM> are not in communication with each other.

The stepping motor <NUM> includes a stator member <NUM> including a coil <NUM>, and a rotor member <NUM>. A pulse signal is input to the coil <NUM> from a control substrate <NUM> that is provided with a drive circuit for driving the stepping motor <NUM> via a power supply portion <NUM>. Then, when a pulse signal is input to the coil <NUM>, the rotor member <NUM> rotates by a rotation angle corresponding to the number of pulses of the pulse signal.

The power transmission mechanism <NUM> is a member that connects the rotor member <NUM> and the rotary shaft <NUM> so as to be able to transmit power. The power transmission mechanism <NUM> includes a plurality of gears. The power transmission mechanism <NUM> may include a planetary gear mechanism.

The stator member <NUM> is fixed to the side wall of the can <NUM>. The rotor member <NUM> is rotatably disposed with respect to the can <NUM> inside the side wall of the can <NUM>. The rotor member <NUM> is formed of a magnetic material and is connected to a solar gear body <NUM> having a coaxial shaft hole.

The rotary shaft <NUM> is disposed in the shaft hole of the solar gear body <NUM> so as to be relatively rotatable. The external teeth of the solar gear body <NUM> mesh with a plurality of planetary gears <NUM>. Each planetary gear <NUM> is rotatably supported by a shaft <NUM> supported by a carrier <NUM>. The outer teeth of each planetary gear <NUM> mesh with an annular ring gear <NUM>.

The ring gear <NUM> is a member that is not rotatable relative to the can <NUM>. The ring gear <NUM> is supported by a holder <NUM> via a cylindrical support member <NUM>.

The planetary gear <NUM> also meshes with an annular second ring gear <NUM>. The second ring gear <NUM> functions as an output gear which is fixed to the rotary shaft <NUM>.

The gear configuration described above constitutes what is known as a mechanical paradox planetary gear mechanism. In a reduction device using a mechanical paradox planetary gear mechanism, by setting the number of teeth of the second ring gear <NUM> to be slightly different from the number of teeth of the ring gear <NUM>, the rotation speed of the solar gear body <NUM> can be reduced by a large reduction ratio and transmitted to the second ring gear <NUM>.

It should be noted that, although a mechanical paradox planetary gear mechanism is used as the power transmission mechanism <NUM>, any power transmission mechanism can be utilized as the power transmission mechanism between the rotor member <NUM> and the rotary shaft <NUM>. A planetary gear mechanism other than a mechanical paradox planetary gear mechanism may be utilized as the power transmission mechanism <NUM>.

A connecting member <NUM> is attached to the lower end of the rotary shaft <NUM>, and the connecting member <NUM> and the upper end of the driver <NUM> rotate integrally in the rotation direction, but are connected so as to be relatively movable in the axial direction.

A male screw <NUM> is provided on the outer peripheral surface of the driver <NUM>. The male screw <NUM> is screwed into a female screw <NUM> provided on a guide member <NUM> that guides the driver. For this reason, when the rotary shaft <NUM> and the driver <NUM> rotate around the axis, the driver <NUM> moves up and down while being guided by the guide member <NUM>. In contrast, the rotary shaft <NUM> is rotatably supported by the solar gear body <NUM> or the guide member <NUM>, and cannot move in the axial direction.

The guide member <NUM> for guiding the driver <NUM> is supported by the holder <NUM>.

The lower end of the driver <NUM> is rotatably connected to the upper end of the valve body <NUM> via a ball <NUM>. As the drivers <NUM> move upward or downward while rotating about the axis, the valve body <NUM> moves upward or downward without rotating about the axis.

The valve body <NUM> is urged upward by a spring member <NUM> disposed between the spring receiving member <NUM> attached to the opening 2a of the lower base member <NUM> and the valve body <NUM>.

When the driver <NUM> moves downward, the valve body <NUM> is pushed downward against the urging force of the spring member <NUM> and displaced. In contrast, when the driver <NUM> moves upward, the valve body <NUM> is pushed upward by the urging force of the coil <NUM> and displaced.

A partition member <NUM> is disposed inside the can <NUM>. In addition, a permanent magnet <NUM> is disposed in an upper space of the can <NUM> formed by the partition member <NUM>. The permanent magnet <NUM> is connected at the vicinity of the upper end of the rotary shaft <NUM> that penetrates the partition member <NUM>.

With the above configuration, it is possible to drive the valve body <NUM> by using the power from the stepping motor <NUM>. The amount of movement of the valve body <NUM> in the direction along the axis L is proportional to the amount of rotation of the rotary shaft <NUM> and the permanent magnet <NUM>. Accordingly, by measuring the rotation angle around the axis of the permanent magnet <NUM> with the angle sensor <NUM> attached to the lower surface of the control substrate <NUM>, it is possible to accurately determine the position of the valve body <NUM> in the direction along the axis L.

Since the rotary shaft <NUM> and the permanent magnet <NUM> do not move up and down with respect to the angle sensor <NUM>, it is possible to accurately calculate the rotation angle of the permanent magnet <NUM> using the angle sensor <NUM>.

The lower portion of the hollow cylindrical holder <NUM> is disposed in the opening 2a of the lower base member <NUM>. A packing <NUM> is disposed between the holder <NUM> and the lower base member <NUM>.

Further, the holder <NUM> is disposed so as to be in contact with the inner wall portion of the housing <NUM>. In addition, a packing <NUM> is disposed between the holder <NUM> and the inner wall portion of the housing <NUM>.

For this reason, the holder <NUM> has a function of preventing the fluid from entering the space in which the stator member <NUM> and the like are disposed, and a function of accommodating the upper end portion <NUM> of valve body <NUM>.

Next, the housing <NUM> will be described. The housing <NUM> includes a cover member 4a and a tube-shaped member 4b. The tube-shaped member 4b of the housing <NUM> is supported by a plate-shaped stay <NUM> bent in an L shape, one end of which is screwed to the lower base member <NUM>.

<FIG> is a bottom view of the cover member 4a, and <FIG> is a perspective view of the cover member 4a. The cover member 4a is formed by connecting a lid portion 4c, which is a flat plate having a trapezoidal shape and a rectangular shape joined together, and an insertion portion 4d having a tube-shaped cross-sectional shape similar to the lid portion 4c. It is preferable that the thickness of the lid portion 4c be <NUM> to <NUM> such that the laser light described later is easily transmitted.

The cover member 4a is a resin based on polyphenylene sulfide (PPS) or polybutylene terephthalate (PBT), and is preferably formed from, for example, a second material having a laser light transmittance of <NUM> to <NUM>%. It should be noted that the cover member 4a may have the natural color of the material, but it is desirable to make the cover member 4a black by adding a pigment such as carbon black to the material.

In <FIG>, on the outer periphery of the insertion portion 4d, a plurality of elongated ribs <NUM> constituted by a raised part of the outer peripheral surface are formed on an outer peripheral surface other than the pair of outer peripheral surfaces along the longitudinal direction.

In <FIG>, a support portion 4f is formed on the lower surface of the lid portion 4c, and the control substrate <NUM> is supported by the support portion 4f. The control substrate <NUM> and the power supply portion <NUM> are connected by a flexible board FP1.

The tube-shaped member 4b includes an upper tube-shaped portion <NUM> having a cross-sectional shape similar to that of the insertion portion 4d, a lower tube-shaped portion 4i extending downward from the upper tube-shaped portion <NUM>, and a connector portion 4j extending horizontally from the lower end of the upper tube-shaped portion <NUM>. The terminals <NUM> disposed inside the connector portion 4j are connected to the control substrate <NUM> via a flexible board FP2. By connecting the connector portion 4j to a partner connector (not illustrated in the figure), power is supplied to the control substrate <NUM> from an external power source, and the stepping motor <NUM> can be driven.

The tube-shaped member 4b is a resin based on PPS or PBT, and has a laser light transmittance that is lower than that of the cover member 4a. For example, the tube-shaped member 4b is preferably formed from a first material having a transmittance of less than or equal to <NUM>%.

When the cover member 4a is joined, the rigidity of the tube-shaped member 4b is increased by using a stepped portion or a curved surface so that the control substrate <NUM> can be positioned accurately.

Next, the joining of the cover member 4a and the tube-shaped member 4b will be described. <FIG> is a diagram for explaining the joining process of the cover member 4a and the tube-shaped member 4b. As illustrated in <FIG>, after accommodating the necessary parts in the tube-shaped member 4b, as illustrated in <FIG>, the insertion portion 4d of the cover member 4a to which the control substrate <NUM> is attached is fitted inside the upper end <NUM> of the tube-shaped member 4b, and the lid portion 4c is brought into contact with the upper end <NUM>.

In this state, the glass flat plate GS is placed on the upper surface of the lid portion 4c and pressed toward the upper end <NUM> of the tube-shaped member 4b. In order to press the lid portion 4c such that no gaps are formed throughout the entire periphery between the lid portion 4c and the upper end <NUM>, it is desirable that the upper surface of the lid portion 4c is flat and the lid portion 4c is pressed using a flat plate. Meanwhile, in order to efficiently transmit the laser beam LB, it is desirable to use glass. Accordingly, in order to satisfy both of these requirements, the glass flat plate GS is used as a jig for pressing the lid portion 4c.

Subsequently, as illustrated in <FIG>, a laser beam LB is emitted from above, passes through the glass flat plate GS and the lid portion 4c, and irradiates the surface of the upper end <NUM>. Here, the lid portion 4c, which is the heat receiving portion, is formed of a second material that substantially transmits the laser beam LB.

On the other hand, since the upper end <NUM>, which is the heat generation portion, is formed of the first material which absorbs the laser light LB, the irradiated portion generates heat, exceeds the glass transition point of the material and melts. In addition, the lid portion 4c, which is the heat receiving portion, is heated and melted by the heat generated at the portion irradiated with the laser beam at the upper end <NUM>. Subsequently, when the irradiation of the laser beam LB ceases, the two melted materials cool and solidify, and welding of the upper end <NUM> and the lid portion 4c is accomplished. The irradiation of the laser beam LB is performed along the entire periphery along the upper end <NUM> of the tube-shaped member 4b, and may be repeated a plurality of times.

At this time, as illustrated in <FIG>, because the outer peripheral surface of the lid portion 4c protrudes outward from the outer peripheral surface of the upper end <NUM> with a distance Δ along a direction intersecting the irradiation direction of the laser beam LB, even if burrs are generated due to the melting of the heat generation portion and grow outward, the interference of the laser beam LB by the burrs is suppressed. As a result, deterioration of the appearance quality due to scorching of burrs or adhesion to the outer surface can be suppressed.

In addition, since the ribs <NUM> are formed on the insertion portion 4d of the cover member 4a, when the insertion portion 4d is fitted inside the tube-shaped member 4b, the ribs <NUM> come into contact with the inner wall of the tube-shaped member 4b in addition to the insertion portion 4d, thereby providing a positioning function in addition to making it possible to suppress rattling of the cover member 4a side with respect to the tube-shaped member 4b. As a result, the angle sensor <NUM> attached to the cover member 4a side and the permanent magnet <NUM> disposed on the tube-shaped member 4b side can be accurately positioned.

Further, since the contact between the ribs <NUM> and the inner wall of the tube-shaped member 4b suppresses the rattling of the cover member 4a with respect to the tube-shaped member 4b, coupled with the fact that the outer peripheral surface of the lid 4c protrudes outward from the outer peripheral surface of the upper end <NUM> at a distance Δ , the influence of burrs can be further suppressed.

It should be noted that, although the use of ultrasonic welding techniques for welding the cover member 4a and the tube-shaped member 4b can also be considered, there is a risk that the control substrate <NUM> or the like may be damaged due to the vibration caused by the application of ultrasonic waves. In contrast, according to the present embodiment, since welding is performed using a laser beam LB, there is no influence due to vibrations. Further, since the irradiation area can be kept small by performing irradiation using a laser beam LB with a narrow diameter, it is possible to avoid the influence of heat generated by the heat generation portion on the control substrate <NUM> or the like.

In particular, by performing irradiation using a laser beam LB with a narrow diameter, even in the case that the wall thickness of the upper end <NUM> is thin, it is possible to perform joining reliably, such that even if the tube-shaped member is small, high sealing performance can be obtained without using a separate component such as a packing or the like.

Hereinafter, the electric valve 1A according to the second embodiment will be described. The present embodiment has a different housing shape from the above-described embodiment, and does not have an angle sensor. The same materials as those in the above-described embodiment can be used as the first material and the second material. The same reference numerals are given to the same configurations as those in the above-described embodiment, and a redundant description thereof will be omitted.

<FIG> is a schematic cross-sectional view illustrating an overview of the electric valve 1A according to the second embodiment. The housing 4A includes a housing main body 4Aa for accommodating the drive system of the electric valve 1A, and a substrate holding portion 4Ab for holding the control substrate <NUM>.

The hollow tube-shaped housing body 4Aa includes an annular portion 4Ac formed by a part of the outer periphery projecting thereof in an annular shape. The power supply portion <NUM> protrudes outward through the annular portion 4Ac.

The housing-shaped substrate holding portion 4Ab includes a bottomed tube-shaped member 4Ad, a cover member 4Ae that shields the end portion of the tube-shaped member 4Ad, and a connector portion 4Af which is joined to the tube-shaped member 4Ad.

A circular concave portion 4Ag that fits with the annular portion 4Ac is formed on the bottom wall of the tube-shaped member 4Ad. Further, the circular concave portion 4Ag and the inside of the tube-shaped member 4Ad communicate with each other by the communication hole 4Ah.

The cover member 4Ae is formed by connecting a lid portion 4Ai, which is a flat plate, and a tube-shaped insertion portion 4Aj in a continuous fashion.

The inner end of the terminal 4Ak disposed inside the connector portion 4Af is connected to the control substrate <NUM> disposed in the tube-shaped member 4Ad. The control substrate <NUM> is supported by and electrically coupled to the power supply portion <NUM> that penetrates the annular portion 4Ac from the inside of the housing body 4Aa and extends into the tube-shaped member 4Ad through the communication hole 4Ah.

Next, the manufacturing process of the housing 4A will be described. <FIG> is a diagram for explaining the manufacturing process of the housing 4A.

Here, the tube-shaped member 4Ad of the substrate holding portion 4Ab is formed of a first material M1 having a low light transmittance and a second material M2 having a high light transmittance. More specifically, in <FIG>, the periphery of the circular concave portion of the tube-shaped member 4Ad (indicated by the white-outlined cross-section) is formed from the second material M2, and the other portions of the tube-shaped member 4Ad (indicated by the dotted cross-section) are formed from the first material M1.

When the first material M1 and the second material M2 are each made of resin, such a tube-shaped member 4Ad can be molded by two-color molding in which materials are simultaneously injected and molded, or alternatively by insert molding or the like, in which one material is inserted into the other material and molded.

The adhesiveness of the resin material can be improved by forming the joint portion between the first material M1 and the second material M2 into a triangular shape or a convex shape. Further, in the case of insert molding, by reducing the volume of the resin material to be molded later with respect to the volume of the resin material to be molded first, the material temperature can be maintained, so that the degree of adhesion can be further improved.

On the other hand, the housing body 4Aa (at least the annular portion 4Ac) is formed of the first material M1, and the cover member 4Ae is formed of the second material M2.

During the manufacturing process of the housing 4A, as illustrated in <FIG>, the circular concave portion 4Ag of the tube-shaped member 4Ad from which the cover member 4Ae and the control substrate <NUM> have been removed is fitted into the annular portion 4Ac of the housing body 4Aa.

While maintaining such a state, the laser beam LB is emitted from the tube-shaped member 4Ad side, transmitted through the second material M2, and irradiated on the annular portion 4Ac. As a result, the annular portion 4Ac can be welded to the tube-shaped member 4Ad.

Claim 1:
An electric valve (<NUM>) comprising:
- a motor (<NUM>) including a rotor member (<NUM>) and a stator member (<NUM>) for applying a rotational force to the rotor member (<NUM>);
- a power transmission mechanism (<NUM>) for converting rotational movement of the rotor member (<NUM>) into axial movement of a valve body (<NUM>);
- a housing (<NUM>) for accommodating the motor (<NUM>) and the power transmission mechanism (<NUM>); and
- a base member (<NUM>) connected to the housing (<NUM>) and provided with a valve seat (<NUM>) to which the valve body (<NUM>) is separated or seated,
wherein the housing (<NUM>) includes:
- a tube-shaped member (4b) provided with a connector portion (4j) configured to be connected to an external power source; and
- a cover member (4a) for shielding the tube-shaped member (4b);
- a heat generation portion formed of a first material;
- a heat receiving portion formed of a second material and bonded to the heat generation portion;
wherein the heat generating portion is a part of the tube-shaped member (4b);
wherein the heat receiving portion is part of the cover member (4a);
wherein said motor (<NUM>) is disposed on the tube-shaped member (4b);
wherein an angle sensor (<NUM>) for detecting the rotation angle of the rotor member (<NUM>) is disposed on the cover member (4a); and
wherein the cover member (4a) comprises:
- an insertion portion (4d) that fits inside an end portion of the tube-shaped member (4b); and
- ribs (<NUM>) formed on an outer peripheral surface of the insertion portion (4d);
wherein a laser light transmittance in said first material is lower than a laser light transmittance in said second material, and
the heat generation portion is welded to the heat receiving portion by irradiating the heat generation portion with a laser beam that has passed through the heat receiving portion.