Patent Description:
Conventionally, as a so-called electrically operated valve for opening and closing valves using an electric motor, there is known a valve which is opened and closed by directly transmitting the rotation of a rotor to a screw mechanism. There is demand for such electrically operated valves to open and close valves under higher load conditions, or to further improve the angular resolution of the valve opening degree.

With respect to this, as illustrated in Patent Document <NUM>, the present applicant has proposed an electrically operated valve in which the rotation of the rotor is decelerated by a planetary gear type deceleration mechanism and transmitted to a screw mechanism. Since the torque per unit rotation of the rotor becomes large in such an electrically operated valve, it can be used even under high load conditions, and the angular resolution of the valve opening degree per single drive pulse can be increased.

Patent Document <NUM> discloses an electrically operated valve according to the preamble of claim <NUM>.

Incidentally, in planetary gear type deceleration mechanisms in which the lower surface of a sun gear member formed integrally with the upper end of a sun gear faces an upper surface of a ring gear, due to this structural configuration, sliding occurs when both come into contact. On the other hand, from the viewpoint of cost reduction, it is generally preferable to form the sun gear and the ring gear from a resin material. However, if the lower surface of the sun gear member and the upper surface of the ring gear formed of the same resin material are slid together, the relative speed between the sliding surfaces of these members is high, and therefore there is a risk of causing premature wear. Therefore, in Patent Document <NUM>, a leaf spring is installed to urge the sun gear member in one direction to separate the sun gear member from the ring gear. However, from the viewpoint of cost reduction, there has been a demand for removing this leaf spring.

It is an object of the present invention to provide an electrically operated valve that has excellent wear resistance while also suppressing the cost.

In order to achieve the above object, the electrically operated valve according to the present invention includes a valve main body having a valve seat, a motor including a stator fixed to the valve main body and a rotor driven to rotate with respect to the stator, a planetary gear type deceleration mechanism configured to decelerate rotation of the rotor to transmit to an output gear, a valve member configured to be movable toward and away from the valve seat in an axial direction, and a feed screw mechanism configured to convert rotational movement of the output gear into movement of the valve member in the axial direction, wherein the planetary gear type deceleration mechanism includes a sun gear coupled to the rotor, a planetary gear engaged with the sun gear, a carrier for rotatably supporting the planetary gear, an annular ring gear engaged with the planetary gear, and a sliding member abutting against an axial end of the sun gear, the output gear has a different number of teeth than the ring gear, and engages with the planetary gear, and the sliding member is made of a different material from the material of the sun gear.

In an example not being part of the claimed invention, the sliding member is preferably an annular body disposed between the sun gear and the carrier and is configured to slide with respect to at least one of them.

According to the invention, the sliding member is an output shaft configured to slide with respect to the axial end of the sun gear, and is connected to the output gear to transmit a rotational force to the feed screw mechanism.

It is preferable that the sun gear is made of a resin material, and the sliding member is made of a metal, ceramic, or glass material.

According to the present invention, it is possible to provide an electrically operated valve that has excellent wear resistance while suppressing the cost.

Hereinafter, an electrically operated valve according to an embodiment of the present invention will be described with reference to the drawings. It should be noted that in the following description of the embodiments and comparative examples, parts and members having the same functions are denoted by the same reference numerals, and redundant description of parts and members denoted by the same reference numerals is omitted.

Here, when "adhesion wear" occurs when two members are slid together, the material on which those members are formed is referred to as the same type of material. Further, a "different material" refers to materials which are not the same material; that is, when "adhesion wear" does not occur when two members are slid together, the material of one member corresponds to a different material with respect to the material of the other member. Examples of different types of materials include materials of different categories when arbitrary materials are classified into categories such as, for example, metals, resins, ceramics, glass, and the like. In addition, the "axial direction" herein refers to the axial direction of the valve main body.

<FIG> is an overall longitudinal cross-sectional view illustrating an electrically operated valve according to an example not being part of the claimed invention. <FIG> is an exploded perspective view of a planetary gear type deceleration mechanism used in the electrically operated valve illustrated in <FIG>, but a part thereof is cut away to facilitate better understanding. <FIG> is an exploded perspective view of the planetary gear and the carrier of the planetary gear type deceleration mechanism illustrated in <FIG>.

The electrically operated valve <NUM> includes a drive unit 1a that is operated by an exciting action and which includes a motor composed of a stator <NUM> and a rotor assembly (hereinafter also called a motor) <NUM>, a gear deceleration unit 1b which receives a rotational driving force from the drive unit 1a and performs gear deceleration to output a decelerated rotational force, and a feed screw mechanism 1c which converts the rotation decelerated by the gear deceleration unit 1b into a displacement in the axial direction using a screw action and outputs the displacement in the axial direction.

The can <NUM> is an air-tight container fixed to the valve main body <NUM> via a bearing member <NUM>, and has a thin-walled cylindrical shape with a top. The drive unit 1a includes a stator <NUM> and a permanent-magnet type rotor assembly <NUM> which is rotationally driven by the stator <NUM>. The stator <NUM> is an exciting device for an electric motor, and is fixedly disposed on the outer peripheral portion of the can <NUM> and is formed by molding a coil <NUM> wound around a bobbin integrally with resin. The rotor assembly <NUM> is rotatably supported inside the can <NUM>. The stator <NUM> and the rotor assembly <NUM> constitute a stepping motor as one example of an electric motor.

The stator <NUM> is detachably fitted to the can <NUM> by a mounting bracket <NUM> formed of a leaf spring. In this example, the dome portion <NUM> formed in the can <NUM> is elastically fitted into a hole <NUM> formed in the mounting bracket <NUM>, thereby positioning the stator <NUM> relative to the can <NUM>. Coils <NUM> are supplied by an external power source via a lead <NUM> for excitation of the stator <NUM>.

The valve main body <NUM> includes a valve chamber <NUM> formed therein, and also a bottom portion <NUM> formed with an orifice <NUM> that opens to the bottom surface of the valve main body <NUM>. A pipe <NUM> that communicates with the side surface of the valve chamber <NUM> and a pipe <NUM> that communicates with the lower end of the orifice <NUM> are fixed to the valve main body <NUM>.

The gear deceleration unit 1b is composed of a planetary gear type deceleration mechanism (hereinafter abbreviated as a "deceleration mechanism") <NUM> for decelerating the rotational speed of the rotor assembly <NUM>.

As illustrated in <FIG>, the deceleration mechanism <NUM> includes a sun gear <NUM> integrated with the rotor assembly <NUM>, a plurality (three in this example) of planetary gears <NUM> engaged with the sun gear <NUM> that are elongated in the axial direction and rotatably supported by a carrier <NUM> formed by molding plastic, for example; a ring gear <NUM> that is arranged concentrically with the sun gear, fixedly supported with respect to the valve main body <NUM>, and engaged with a part (the upper portion) of each planetary gear <NUM>; and an output gear <NUM> formed in a cylindrical shape with a bottom that has a number of inner teeth slightly different from the number of teeth of the ring gear <NUM> (that is, in a profile-shifted relationship with the ring gear <NUM>). The sun gear <NUM>, the carrier <NUM>, the ring gear <NUM>, and the output gear <NUM> are formed of polyphenylene sulfide resin (PPS).

In <FIG>, the carrier <NUM> includes a lower disk 42b formed by implanting three column portions 42a in parallel on the outer periphery of the upper surface, and an annular plate 42c. A cylindrical protrusion 42d is formed on the upper end of each of the column portion 42a, and three corresponding through holes 42e are formed in the plate 42c.

On the other hand, the planetary gear <NUM> formed of a zinc alloy has cylindrical convex portions 43a (only the upper end side is shown) at both ends in the axial direction. In opposition to this, an axial hole 42f is formed in the lower disk 42b, and an axial hole <NUM> is formed in the plate 42c.

The carrier <NUM> and the planetary gear <NUM> are assembled in the following manner. First, the planetary gear <NUM> is assembled to the lower disk 42b while the convex portion 43a is fitted to the axial hole 42f, and then the plate 42c is assembled such that the convex portion 43a is further fitted to the axial hole <NUM>, and the through hole 42e is engaged to the protrusion 42d of the column portion 42a. Thereafter, the plate 42c can be fixed to the column portion 42a by welding the protrusion 42d using, for example, an ultrasonic welding means. Since the axial holes 42f and <NUM> and the convex portion 43a are rotatable relative to each other, the planetary gear <NUM> is freely rotatable with respect to the carrier <NUM>. It should be noted that the method of assembling the carrier <NUM> is not limited to the above.

As can be seen in <FIG>, each planetary gear <NUM> engages with the ring gear <NUM>, and at the same time engages with the inner teeth of the output gear <NUM> at one part (the lower portion). In <FIG>, the rotational force of the rotor assembly <NUM> decelerated by the deceleration mechanism <NUM> is transmitted to the output shaft <NUM> (the driver) of the feed screw mechanism 1c through the output gear <NUM>. An upper end of the output shaft <NUM>, which is made of stainless steel, is coaxially fixed to the output gear <NUM>.

In the rotor assembly <NUM>, a cylindrical body <NUM> serving as a peripheral wall and a sun gear member <NUM> disposed at the center are integrally molded into a cylindrical shape with a top by a plastic material (here, PPS) that contains a magnetic material, and the rotor assembly <NUM> is rotatably disposed inside the can <NUM> by a shaft <NUM> that passes through the sun gear member <NUM> in the axial direction. As illustrated in <FIG>, the sun gear <NUM> is formed on the outer periphery of a cylinder implanted in the center of the sun gear member <NUM>. The ring gear <NUM> is, for example, a ring-shaped gear formed by molding plastic, and is fixed to an upper portion of a gear case <NUM>, which is a cylindrical member whose lower portion is fitted to an upper portion of the valve main body <NUM>, as illustrated in <FIG>.

According to such a configuration, when the sun gear <NUM> to which the output rotation of the electric motor is input rotates around itself, the planetary gear <NUM> engaged with the sun gear <NUM> and the ring gear <NUM> revolves around the sun gear <NUM> while rotating. Since the planetary gear <NUM> engages with the output gear <NUM> which is profile-shifted in relation to the ring gear <NUM>, this rotation of the planetary gear <NUM> causes the output gear <NUM> to rotate at a very high deceleration rate relative to the ring gear <NUM>, for example, on the order of <NUM> to <NUM>, depending on the degree of profile-shift (the difference in the number of teeth). A planetary gear mechanism in which a planetary gear <NUM> engages with a ring gear <NUM> and an output gear <NUM> in a profile-shifted relationship is referred to as a mechanical paradox planetary gear mechanism.

According to the present example not being covered by the appended claims, there is provided a sliding member which abuts against the axial direction end of the sun gear <NUM>, and this sliding member is formed of a different material than the sun gear <NUM>. Therefore, since wear (primarily adhesion wear) does not occur from sliding with the sun gear <NUM>, it is possible to suppress the wear of the sun gear <NUM> without urging the sun gear <NUM> away from the carrier <NUM> using a spring member or the like. Hereinafter, the sliding member will be specifically described.

<FIG> is an enlarged view illustrating the inside of the can <NUM> in the configuration of <FIG>. As illustrated in <FIG>, the lower disk 42b of the carrier <NUM> has a circular opening <NUM> at the center thereof which passes through the shaft <NUM>. In addition, the sun gear <NUM> through which the shaft <NUM> penetrates in the axial direction has an annular boss 41a at the tip (lower end), as partially illustrated in <FIG>.

Further, a thin annular body <NUM> (illustrated by the hatching in <FIG>) made of stainless steel is disposed between the annular boss 41a and the lower disk 42b. The annular body <NUM> that serves as the sliding member may be a washer that has the same diameter as the boss 41a.

Referring to <FIG>, the feed screw mechanism 1c includes a cylindrical bearing <NUM>, a screw shaft <NUM>, and a ball <NUM>. The lower end of the cylindrical bearing <NUM> is fitted into the valve main body <NUM>, and is attached to the stepped portion <NUM> of the valve main body <NUM> in a state of being supported via the upper flange portion <NUM> so as not to be able to be pulled out from the valve main body <NUM> by means of press working or the like.

The cylindrical bearing <NUM> supports the output gear <NUM> of the deceleration mechanism <NUM> from the lower side at its upper end surface, and the output shaft <NUM> of the deceleration mechanism <NUM> is inserted into the hollow upper portion of the cylindrical bearing <NUM>. A male screw portion <NUM> formed on the outer periphery of the screw shaft <NUM> is screwed to the female screw portion <NUM> formed in the hollow lower portion of the cylindrical bearing <NUM>. In addition, a convex portion <NUM>, which is a flat driver portion, is provided on the screw shaft <NUM> and is inserted into a slit-shaped concave portion <NUM> formed in the lower end portion of the output shaft <NUM> of the deceleration mechanism <NUM>, and transmits the rotation of the output shaft <NUM> to the screw shaft <NUM>. A concave portion is formed in the lower end of the screw shaft <NUM>, and the ball <NUM> is fixed to the screw shaft <NUM> in a state in which it is fitted into the concave portion.

The rotation of the screw shaft <NUM> is converted into movement in the axial direction by the screw action with the cylindrical bearing <NUM>, and transmitted to the valve shaft <NUM> side via the ball <NUM> and the ball bearing member <NUM>. It should be noted that the screw shaft <NUM> may be provided with a concave portion, and the output shaft <NUM> may be provided with a convex portion inserted into the concave portion.

When the screw shaft <NUM> is moved in the valve opening direction in the feed screw mechanism 1c, in order to remove backlash between the female screw portion <NUM> and the male screw portion <NUM>, the valve main body <NUM> is provided with a coil spring <NUM> for urging the valve shaft <NUM> in the valve opening direction. In order to support the coil spring <NUM>, a bottomed cylindrical spring support <NUM> made of metal is disposed in the valve chamber <NUM>. The spring support <NUM> includes a cylindrical peripheral wall <NUM> which opens and covers a circular space between the upper outer periphery of the valve shaft <NUM> and itself, an upper flange portion <NUM> extending radially outward from the upper end, a lower flange portion <NUM> extending radially from the lower end of the peripheral wall <NUM> to the outer periphery of the valve shaft <NUM>, and a cylindrical guide portion <NUM> extending coaxially with the valve shaft <NUM> from the lower flange portion <NUM>. The inner circumference of the guide portion <NUM> slides with respect to the outer circumferential surface of the valve shaft <NUM>, and forms a hole <NUM> for guiding the valve shaft <NUM>.

The coil spring <NUM> disposed in the space between the valve shaft <NUM> and the peripheral wall <NUM> is supported in a compressed state as a result of its upper end abutting against the large diameter portion <NUM> of the valve shaft <NUM> and its lower end abutting against the lower flange portion <NUM> of the spring support <NUM>. The upper flange portion <NUM> of the peripheral wall <NUM> is fixed by being interposed between the stepped portion <NUM> formed at the lower end of the valve hole <NUM> of the valve main body <NUM> and the lower end of the cylindrical bearing <NUM> mounted in the valve hole <NUM>.

The valve shaft <NUM> is constantly urged in the valve opening direction (the direction of the feed screw mechanism 1c) by the spring force of the coil spring <NUM> held in the compressed state in the spring support <NUM>, and when the valve shaft <NUM> is pushed down in the valve closing direction by the force from the feed screw mechanism 1c, the valve shaft <NUM> is lowered against the spring force of the coil spring <NUM>, and the valve member <NUM> formed at the distal end of the valve shaft <NUM> is seated on the valve seat <NUM> to close the orifice <NUM>.

The screw shaft <NUM> can be rotated a small number of revolutions with respect to the rotation of the rotor assembly <NUM>, and the axial displacement of the screw shaft <NUM> corresponding to this rotation can be controlled down to a small amount of displacement, so that the position of the valve shaft <NUM> with respect to the valve seat <NUM> is positioned with a high resolution by the gear deceleration unit 1b, the flow path area between the valve member <NUM> and the orifice <NUM> is controlled with a high accuracy, and the flow rate of the refrigerant passing therethrough can be adjusted with a high accuracy. In other words, valve opening control with high angular resolution is achieved. When operating the feed screw mechanism 1c in the valve opening direction, the valve shaft <NUM> moves in accordance with the rise of the screw shaft <NUM> as a result of the spring force of the coil spring <NUM>,.

In the electrically operated valve illustrated in <FIG>, refrigerant is introduced into the can <NUM> through a minute gap between the inside of the guide portion <NUM> of the spring support <NUM> (the hole <NUM>) and the valve shaft <NUM>, and a gap appropriately provided in the valve main body <NUM>, the cylindrical bearing <NUM>, and the like. The minute gap between the guide portion <NUM> of the spring support <NUM> and the valve shaft <NUM> has an effect of preventing foreign matter which may be contained in the refrigerant from entering the can <NUM>.

In the electrically operated valve <NUM> of the present embodiment, the output gear <NUM> and the output shaft <NUM> move as one unit in the rotational and axial directions. Since such a structure is provided, it is unnecessary to provide a complicated coupling structure between the output gear and the output shaft, and a simple electrically operated valve <NUM> can be provided.

The operation of the electrically operated valve <NUM> according to the present example will be described. When electric power is supplied from an external power source through the leads <NUM> in response to a valve opening signal, the stator <NUM> generates a magnetic force. The rotor assembly <NUM> is rotationally driven based on this magnetic force, and generates a rotational force in a predetermined direction. This rotational force is transmitted to the sun gear <NUM>, decelerated via the deceleration mechanism <NUM>, and transmitted to the output gear <NUM>. Further, since the rotational movement of the output gear <NUM> is converted into the upward movement of the screw shaft <NUM> through the feed screw mechanism 1c, the valve shaft <NUM> urged by the spring force of the coil spring <NUM> follows the upward movement of the screw shaft <NUM>, and the valve member <NUM> separates from the valve seat <NUM> to allow the passage of the refrigerant. On the other hand, when electric power of the inverse characteristic is supplied from an external power source via the lead <NUM> in response to a valve closing signal, the valve shaft <NUM> descends against the spring force of the coil spring <NUM> by a operation opposite to that described above, and the valve member <NUM> is seated on the valve seat <NUM> to prevent passage of the refrigerant.

In the present example, since the carrier <NUM> is mounted on the bottom surface of the output gear <NUM>, the carrier <NUM> and the planetary gear <NUM> are also raised and lowered in accordance with the raising and lowering of the output gear <NUM>.

In such a case, supposing that neither the prior art spring member nor the annular body <NUM> were provided, the lower surface of the sun gear member <NUM> provided on the rotor assembly <NUM> would come into contact with the upper surface of the ring gear <NUM> and these surfaces would slide relative to one another during the operation of the deceleration mechanism.

Accordingly, in order to prevent such a problem, in this example, whis is not part of the claimed invention, an annular body <NUM> made of stainless steel, which can be manufactured relatively inexpensively, is disposed between the boss 41a and the lower disk 42b as a sliding member. As a result, relative sliding occurs results between the boss 41a and the annular body <NUM>, or between the annular body <NUM> and the lower disc 42b, but since the boss 41a, the lower disc 42b, and the annular body <NUM> are different materials from each other, wear does not occur even under severe conditions, and it is possible to avoid premature wear of the boss 41a.

<FIG> is a cross-sectional view of the inside of a can of an electrically operated valve according to the claimed invention. In this embodiment, no annular body is used, and instead, the output shaft <NUM> (illustrated by the hatching in <FIG>) also serves as the sliding member that slides to the boss 41a of the sun gear <NUM>. That is, the upper end portion of the output shaft <NUM> functions as the sliding member.

More specifically, the circular opening <NUM> provided at the center of the lower disk 42b of the carrier <NUM> is made larger in diameter, and the upper end of the output shaft <NUM> is extended upward to be fitted into the circular opening <NUM>. At this time, the upper end surface of the output shaft <NUM> that is exposed from the lower disk 42b comes into contact with the lower surface of the boss 41a of the sun gear <NUM>, and these two surfaces slide with each other during the operation of the electrically operated valve <NUM>. Since the boss 41a is made of PPS while the output shaft <NUM> is made of stainless steel, the two are made of different materials, such that wear does not occur during sliding, and premature wear of the boss 41a can be avoided. According to the present embodiment, in addition to omitting the spring member of the related art, the wear of the boss 41a can be suppressed without adding parts, and as a result, the assembly process can be simplified. The rest of the configuration is the same as that of the above-described embodiments.

It should be noted that, the present invention is not limited to the above embodiments. Within the scope of the present invention, which is defined by the appended claims, any of the components of the above embodiments can be modified. In addition, any component can be added or omitted in the above-described embodiments.

Claim 1:
An electrically operated valve comprising:
a valve main body (<NUM>) having a valve seat (<NUM>);
a motor (1a) including:
a stator (<NUM>) fixed to the valve main body (<NUM>), and
a rotor (<NUM>) driven to rotate with respect to the stator (<NUM>),
a planetary gear type deceleration mechanism (<NUM>) configured to decelerate rotation of the rotor (<NUM>) to transmit to an output gear (<NUM>);
a valve member (<NUM>) configured to be movable toward and away from the valve seat (<NUM>) in an axial direction;
an output shaft (<NUM>); and
a feed screw mechanism (1c) configured to convert rotational movement of the output shaft (<NUM>) into movement of the valve member (<NUM>) in the axial direction;
wherein the output shaft (<NUM>) is connected to the output gear (<NUM>) to transmit a rotational force to the feed screw mechanism (1c), wherein:
the planetary gear type deceleration mechanism (<NUM>) includes:
a sun gear (<NUM>) coupled to the rotor (<NUM>), a shaft (<NUM>) passing through the sun gear (<NUM>) in the axial direction,
a planetary gear (<NUM>) engaged with the sun gear (<NUM>),
a carrier (<NUM>) for rotatably supporting the planetary gear (<NUM>), comprising a lower disk (42b) having a circular opening (<NUM>) at the center thereof,
an annular ring gear (<NUM>) engaged with the planetary gear (<NUM>),
the output gear (<NUM>) is formed in a cylindrical shape with a bottom, wherein said output gear (<NUM>) has a number of inner teeth that differs from the number of teeth of the ring gear (<NUM>), and engages with the planetary gear (<NUM>),
characterized in that,
an upper end of the output shaft (<NUM>) passes through the circular opening (<NUM>) of the lower disk (42b), the upper end of the output shaft (<NUM>) is extended upward to be fitted into the circular opening (<NUM>),
the sun gear (<NUM>) has an annular boss (41a) at its axial end, and an upper end surface of the output shaft (<NUM>) that is exposed from the lower disk (42b) and passing through the circular opening (<NUM>) abuts on the annular boss (41a) of the sun gear (<NUM>) such that the upper end surface of the output shaft (<NUM>) and a lower surface of the boss (41a) of the sun gear (<NUM>) slide with each other during the operation of the electrically operated valve (<NUM>), and
the output shaft (<NUM>) is made of a different material from the material of the sun gear (<NUM>).