JP2019167982A - Electric valve - Google Patents

Abstract

To provide an electric valve capable of stabilizing energy loss of (passing) fluid flowing through a valve port, and also suppressing variation of a flow rate to improve controllability.SOLUTION: At the lowest position (origin position) of a valve body 14, a lap amount (overlap amount) L in an ascending/descending direction between a straight part 46s of a valve port 46 and a straight part 14s of the valve body 14 corresponding to a pipe length L is set to 0.05 mm or more and 0.4 mm or less so as to be as small as possible within a setting range of a valve opening pulse, and the surface roughness Rz of the straight part 46s of the valve port 46 and the straight part 14s of the valve body 14 is set to 5.7 μm or less that can be realized by, for example, cutting.SELECTED DRAWING: Figure 2

Description

  The present invention relates to an electric valve including a valve body provided with a valve chamber and a valve port (orifice), and a valve body that changes a flow rate of fluid flowing through the valve port according to a lift amount, and in particular, a heat pump. The present invention relates to a motor-operated valve suitable for controlling a refrigerant flow rate in a type air conditioning system or the like.

  As this type of electric valve, for example, the one described in Patent Document 1 is already known.

  FIG. 7 shows the main parts and flow characteristics of the conventional motor-operated valve. The motor-driven valve of the illustrated conventional example flows through the valve body 46 provided with a valve chamber 40a, a valve seat 46a, and a valve port 46 connected to the valve seat 46a, and the lift amount from the valve seat 46a. A valve body 14 that changes the flow rate of the fluid. The valve body 14 includes, for example, a guide bush provided with a male screw portion, a valve shaft holder provided with a female screw portion, as described in Patent Document 1 and the like, and The valve seat 46a is lifted and lowered by a screw feed type lifting drive mechanism composed of a stepping motor or the like.

  The valve body 14 includes a straight portion 14s having a cylindrical surface (the outer diameter is constant in the up-and-down direction) and a flow rate of fluid flowing through the valve port 46 in accordance with the lift amount, which is connected to the lower side (tip side) of the straight portion 14s. And a curved surface portion 14b for changing. The curved surface portion 14b has a plurality of steps (here, two steps) of inverted frustoconical taper whose control angle (intersection angle between the central axis O of the valve element 14 and a line parallel to it) increases stepwise as it approaches the tip. It has a surface part (the upper taper surface part 14ba and the lower taper surface part 14bb). In addition, as the curved surface portion 14b, an elliptical shape (elliptical surface portion) whose outer peripheral surface is gradually curved (increases in curvature) as it approaches the tip is also known.

  On the other hand, the valve port 46 includes a straight portion 46s having a cylindrical surface (the inner diameter is constant in the up-and-down direction) connected to the valve seat 46a, and a cone that is connected to the lower side of the straight portion 46s and has an inner diameter that increases toward the lower side. And an enlarged diameter portion 46c made of a base surface.

  In this conventional motor-operated valve, as shown in FIG. 7, the valve body 14 is lifted and lowered with respect to the valve seat 46a by the screw feed type lifting drive mechanism, whereby the valve body 14 and the valve seat 46a are moved. The gap (lift amount, valve opening) is increased / decreased to adjust the flow rate through the valve port of the fluid such as the refrigerant. Further, when the valve body 14 is at the lowest lowered position (also referred to as an origin position, where the number of pulses supplied to the motor is 0 pulse), a gap of a predetermined size is provided between the valve body 14 and the valve seat 46a. A predetermined amount of passage flow rate (also referred to as 0 pulse flow rate) is ensured between the straight portion 14s of the valve body 14 and the straight portion 46s of the valve port 46. Therefore, for example, the valve element 14 can be prevented from biting into the valve seat 46a, and controllability in a low flow rate region can be ensured. Thus, even when the valve body 14 is in the lowest lowered position (normally in a fully closed state), a type in which a gap of a predetermined size is formed with the valve seat 46a is referred to as a valveless type. Called.

  In addition to the above-described valve-less type motor operated valve, as shown in FIG. 8, the motor valve of this type includes an inverted truncated cone surface that is attached to the valve seat 46a on the upper side of the straight portion 14s of the valve body 14. There is already known a valve-closing type in which the seating surface portion 14a is provided and the valve body 14 is seated on the valve seat 46a when the valve body 14 is in the lowest lowered position.

JP 2017-180525 A

  However, for example, in a motor-operated valve that performs low flow rate control (micro flow rate control) as described above, the gap between the straight part of the valve port and the straight part of the valve body inserted through the valve port is small (narrow). Therefore, in the low flow rate control region, there is a concern that the energy loss of the fluid flowing (passing through) the valve port increases, and as a result, the flow rate variation increases.

  The present invention has been made in view of the above-described problems, and the object of the present invention is to stabilize the energy loss of the fluid flowing (passing through) the valve port, and to control the variation of the flow rate. An object of the present invention is to provide an electric valve that can improve the performance.

  In order to solve the above-described problems, the present inventors have intensively studied, for example, in a motor-operated valve that performs minute flow control as described above, the flow rate variation of the fluid flowing through the valve port can be easily reduced. The setting range of the straight part of the mouth and the straight part of the valve disc was found.

  Specifically, the energy loss ΔE of the fluid flowing through the valve port is expressed by the Darcy-Weisbach equation expressed by the following equation (1). Can be suppressed.

  Here, among the design elements of the motor-operated valve described above, design elements capable of changing the energy loss are the pipe length L and the pipe friction coefficient λ (that is, surface roughness Rz (JIS B 0601-2001 described later). )).

  The pipe friction coefficient λ is determined by the surface roughness Rz (Colebrook equation and Karman-Nikuradse equation) represented by the following equations (2) and (3). Affected by JIS B 0601-2001).

  Based on the above empirical formula, in the Moody chart (Moody chart), the pipe friction coefficient λ can be obtained from the Reynolds number Re and the relative roughness Rz / D (D: pipe diameter).

  Since the Reynolds number Re is determined by the fluid (refrigerant) characteristics and the differential pressure, by appropriately designing the pipe length L and the surface roughness Rz among the design elements of the electric valve described above, the fluid flowing through the valve port It is considered that the energy loss ΔE can be stabilized at a low value and the variation in flow rate can be suppressed.

  That is, the electric valve according to the present invention basically includes a valve body having a valve body and a valve chamber into which fluid is introduced and led through the valve opening, and a flow rate of fluid flowing through the valve opening in accordance with a lift amount. And a valve body side straight portion having a cylindrical surface is provided in the valve port, and the valve body is inserted into the valve port side straight portion according to a lift amount. And a valve body side straight portion having a constant outer diameter and smaller diameter than the valve port side straight portion is provided, and at the lowest descending position of the valve body, the valve port side straight portion and the valve body side straight portion in the ascending / descending direction. The wrap amount is set to 0.05 mm or more and 0.4 mm or less, and the surface roughness Rz of the valve port side straight part and the valve body side straight part is set to 5.7 μm or less. .

  In a preferred aspect, at the lowest lowered position of the valve body, the lower end portion of the valve port side straight portion is positioned at the same position as or higher than the lower end portion of the valve body side straight portion, and The diameter of the lower side of the valve port side straight part is made larger than the diameter of the valve port side straight part.

  In a more preferred embodiment, the lower end side of the valve port side straight portion has an enlarged diameter portion made of a truncated cone surface having an inner diameter larger than that of the valve port side straight portion, or a circle perpendicular to the valve port side straight portion. A stepped surface portion having an annular flat surface is provided continuously.

  In another preferred embodiment, the length of the valve body side straight portion in the ascending / descending direction is set to 0.05 mm or more and 0.5 mm or less.

In another preferred embodiment, an inner diameter of the valve port side straight portion is D [mm], an opening area of the valve port side straight portion is A1 [mm ² ], and the valve port side straight portion and the valve body side straight portion are The opening area defined between them is set to 1.0 ≦ D ≦ 2.5 and A2 / A1 ≦ 0.056D ⁻² with A2 [mm ² ].

  In a further preferred aspect, the opening area defined between the valve port side straight portion and the valve body side straight portion is viewed in a cross section perpendicular to the ascending / descending direction when the valve body passes through the valve port. The minimum area of the opening area defined between the valve opening and the valve body.

  In another preferred embodiment, the valve port side straight portion is the narrowest portion of the valve port.

  In another preferred embodiment, a curved surface portion that is continuously or stepwise increased as the curvature or control angle approaches the distal end is continuously provided on the distal end side of the valve body-side straight portion in the valve body.

  In a further preferred aspect, the curved surface portion has a tapered surface portion composed of one or a plurality of steps of inverted truncated cone surfaces.

  In a further preferred aspect, the curved surface portion is designed so as to obtain an equal percentage characteristic or a characteristic approximate thereto as a flow characteristic.

  In another preferred aspect, the apparatus further includes a can provided in the valve body and a stator that is externally mounted on the can.

  According to the present invention, at the lowest descending position (origin position) of the valve body, the lap amount in the ascending / descending direction of the valve-portion-side straight portion and the valve-body-side straight portion corresponding to the tube length L is set as the valve opening pulse setting range. By setting the surface roughness Rz of the valve-portion-side straight portion and the valve-body-side straight portion to 5.7 μm or less that can be realized by cutting, for example, The energy loss of the fluid flowing through the valve port in the low flow rate control region can be stabilized at a low value without greatly changing the flow rate, and the controllability can be improved by suppressing variations in the flow rate. .

The longitudinal cross-sectional view which shows one Embodiment of the motor operated valve which concerns on this invention. The principal part expansion longitudinal cross-sectional view which expands and shows the principal part of the electrically operated valve shown by FIG. The figure which shows the relationship between the diameter (phiD) of a valve port, and flow-path cross-sectional area ratio (A2 / A1). The principal part expansion longitudinal cross-sectional view which expands and shows the principal part (the 1) of the other example of the electrically operated valve shown by FIG. The principal part expansion longitudinal cross-sectional view which expands and shows the principal part (the 2) of the other example of the electrically operated valve shown by FIG. The principal part expansion longitudinal cross-sectional view which expands and shows the principal part (the 3) of the other example of the electrically operated valve shown by FIG. The figure which shows an example of the principal part and flow volume characteristic of the conventional motor operated valve. The figure which shows the principal part of the conventional motor operated valve, and another example of flow characteristics.

  Embodiments of the present invention will be described below with reference to the drawings. In each drawing, gaps formed between members, separation distances between members, etc. may be exaggerated for easy understanding of the invention and for convenience of drawing. is there. Further, in this specification, descriptions representing positions and directions such as up and down and left and right are based on the directional arrow display of FIG. 1 and do not indicate positions and directions in the actual use state.

  FIG. 1 is a longitudinal sectional view showing an embodiment of a motor-operated valve according to the present invention.

  The motor-driven valve 1 of the illustrated embodiment is used for adjusting the refrigerant flow rate in, for example, a heat pump air conditioning system, and mainly includes a valve shaft 10 having a valve body 14, a guide bush 20, and a valve shaft holder. 30, a valve body 40, a can 55, a stepping motor 50 comprising a rotor 51 and a stator 52, a compression coil spring 60, a retaining latch member 70, a screw feed mechanism 28, and a lower stopper mechanism 29. Is provided.

  The valve shaft 10 has an upper small diameter portion 11, an intermediate large diameter portion 12, and a lower small diameter portion 13 from above, and a fluid (refrigerant) that flows through the valve port 46 at the lower end portion of the lower small diameter portion 13. The valve body 14 for controlling the passage flow rate is integrally formed.

  As can be understood by referring to FIG. 2 together with FIG. 1, the valve body 14 has a cylindrical surface slightly smaller in diameter than the lower small diameter portion 13 of the valve shaft 10 from the upper side (the valve chamber 40 a side). The flow rate of the fluid flowing through the valve port 46 is changed according to the lift amount from the valve seat 46a connected to the straight portion (valve body side straight portion) 14s composed of a constant) and the lower side (tip end side) of the straight portion 14s. And a curved surface portion 14b. The curved surface portion 14b has a plurality of steps (here, two steps) of inverted frustoconical taper whose control angle (intersection angle between the central axis O of the valve element 14 and a line parallel to it) increases stepwise as it approaches the tip. It has a surface part. Here, the plurality of (two-stage) inverted frustoconical tapered surface portions are an upper tapered surface portion 14ba made of an inverted truncated cone surface and a lower tapered surface portion 14bb made of an inverted truncated cone surface having a control angle larger than that of the upper tapered surface portion 14ba. And have.

  In this example, the length b of the straight portion 14s in the ascending / descending direction (vertical direction) is set to 0.05 mm or more and 0.5 mm or less. The outer diameter of the straight portion 14s of the valve body 14 (and the inner diameter of the straight portion 46s of the valve port 46 described later) needs to be processed and managed with a tight tolerance (for example, at a level of several μm) in order to produce a minute flow rate. However, by making the length b of the straight portion 14s in the ascending / descending direction 0.05 mm or more and 0.5 mm or less, it is possible to improve workability and facilitate dimensional measurement and management.

  The guide bush 20 includes a cylindrical portion 21 that is inserted in a state in which the valve shaft 10 (the intermediate large-diameter portion 12) is relatively movable (slidable) in the direction of the axis O and is relatively rotatable about the axis O, and The cylinder portion 21 extends upward from the upper end portion, has an inner diameter larger than that of the cylinder portion 21, and is inserted into the upper end side of the intermediate large diameter portion 12 and the lower end side of the upper small diameter portion 11 of the valve shaft 10. And an installation part 22. On the outer periphery of the cylindrical portion 21 of the guide bush 20, one side of a screw feeding mechanism 28 that raises and lowers the valve body 14 of the valve shaft 10 with respect to the valve seat 46 a of the valve body 40 in accordance with the rotational drive of the rotor 51 is configured. A fixing screw portion (male screw portion) 23 is formed. Further, the lower portion of the cylindrical portion 21 (the portion below the fixing screw portion 23) has a large diameter and serves as a fitting portion 27 to the fitting hole 44 of the valve body 40. A lower stopper 25 is screwed and fixed to the fixing screw portion 23 (below the valve shaft holder 30), and the valve shaft holder 30 (that is, the valve shaft holder) is fixed to the outer periphery of the lower stopper 25. A fixed stopper body 24 constituting one side of a lower stopper mechanism 29 for restricting the downward rotation of the valve shaft 10) connected to 30 is integrally projected. The upper surface 27a of the fitting portion 27 is a stopper portion that regulates the downward movement of the lower stopper 25 (in other words, defines the lower movement limit position or the lowest movement position of the lower stopper 25).

  The valve shaft holder 30 includes a cylindrical portion 31 into which the guide bush 20 is inserted and a ceiling portion 32 through which an insertion hole 32a through which the upper end portion of the valve shaft 10 (the upper small diameter portion 11 thereof) is inserted. Have. On the inner periphery of the cylindrical portion 31 of the valve shaft holder 30, a movable screw portion (female screw portion) 33 that is screwed with the fixed screw portion 23 of the guide bush 20 and constitutes the screw feeding mechanism 28 is formed. A movable stopper body 34 constituting the other of the lower stopper mechanism 29 is integrally projected at the lower end of the outer periphery of the cylindrical portion 31.

  The valve shaft holder 30 improves the wear resistance of the movable screw portion (female screw portion) 33 and the movable stopper body 34 by, for example, blending carbon filler (CF) with polyphenylene sulfide (PPS) resin as a base material. can do. Similarly, the slidability of the movable screw portion 33 can be improved by blending polytetrafluoroethylene (PTFE) or graphite (C).

  Further, between the terrace surface formed between the upper small diameter portion 11 and the intermediate large diameter portion 12 of the valve shaft 10 and the lower surface of the ceiling portion 32 of the valve shaft holder 30, the upper small diameter of the valve shaft 10 is provided. The valve shaft 10 and the valve shaft holder 30 are energized in a direction away from each other in the ascending / descending direction (axis O direction) so that the valve shaft 10 (valve element 14) is always lowered downward. A compression coil spring 60 urging in the (valve closing direction) is mounted.

  The said valve main body 40 is comprised from cylindrical bodies, such as brass and SUS, for example. The valve body 40 has a valve chamber 40a into which fluid is introduced and led, and a first conduit 41a is connected and fixed to a first lateral opening 41 provided on a side portion of the valve chamber 40a by brazing or the like. An insertion hole through which the valve shaft 10 (the intermediate large-diameter portion 12) can be relatively moved (slided) in the direction of the axis O and is relatively rotatable about the axis O is inserted into the ceiling of the valve chamber 40a. 43 and a lower portion (fitting portion 27) of the guide bush 20 are fitted and fixedly fitted, and a fitting hole 44 is formed, and a second vertical opening 42 provided in the lower portion of the valve chamber 40a Two conduits 42a are connected and fixed by brazing or the like. In addition, a valve seat 46 having a valve seat 46a with which the valve body 14 comes into contact with, separates from, or closes to is formed in a valve seat 45 formed of a bottom wall provided between the valve chamber 40a and the second opening 42. ing.

  In this example, the valve port 46 is formed by a straight portion 46s having a cylindrical surface (an inner diameter is constant in the ascending / descending direction) connected to the lower side of the valve seat 46a, as can be understood by referring to FIG. 2 together with FIG. Has been.

  The inner diameter of the valve seat 46a and the straight portion 46s (that is, the diameter of the valve port 46) (φD) is smaller than the lower small diameter portion 13 of the valve shaft 10 and is inserted into the valve port 46 (the straight portion 46s thereof). The valve body 14 is designed to have a slightly larger diameter than the outer diameter (φd) of the straight portion 14s.

  Further, here, when the movable stopper body 34 of the valve shaft holder 30 and the fixed stopper body 24 of the lower stopper 25 fixed to the guide bush 20 come into contact with each other, the valve body 14 is at the lowest lowered position (origin position). Dimensional shape of each part so that a lap amount (overlap amount) L between the straight part 14s of the valve body 14 and the valve port 46 (straight part 46s) in the ascending / descending direction is 0.05 mm or more and 0.4 mm or less. Is set (the state shown in FIGS. 1 and 2) (detailed later).

  On the other hand, a flange plate 47 is fixed to the upper end portion of the valve main body 40 by caulking or the like, and a lower end portion of a cylindrical can 55 with a ceiling is formed on a step portion provided on the outer periphery of the flange plate 47. Sealed and joined by butt welding.

  A rotor 51 is rotatably disposed inside a can 55 provided on the valve body 40 and outside the guide bush 20 and the valve shaft holder 30. The rotor 51 is rotated outside the can 55. In order to drive, a stator 52 including a yoke 52a, a bobbin 52b, a stator coil 52c, a resin mold cover 52d, and the like is disposed. A plurality of lead terminals 52e are connected to the stator coil 52c, and a plurality of lead wires 52g are connected to these lead terminals 52e via a substrate 52f, and are arranged in the can 55 by energization excitation to the stator coil 52c. The existing rotor 51 rotates about the axis O.

  The rotor 51 disposed in the can 55 is engaged and supported by the valve shaft holder 30, and the valve shaft holder 30 rotates together with the rotor 51 (detailed structure). (See Patent Document 1 above).

  On the upper side of the rotor 51 and the valve shaft holder 30, the valve shaft holder 30 and the rotor 51 are prevented from moving relative to each other in the ascending / descending direction (in other words, the rotor 51 is pressed downward against the valve shaft holder 30). In order to connect the shaft 10 and the valve shaft holder 30, a push nut 71 fitted and fixed to the upper end portion of the valve shaft 10 (the upper small diameter portion 11 thereof) by press-fitting, welding or the like, and the push nut 71 and the rotor 51 And a retaining member 70 that includes a rotor retainer 72 made of a disk-like member having an insertion hole 72a through which the upper end of the valve shaft 10 is inserted. ing. That is, the rotor 51 is sandwiched between the valve shaft holder 30 biased upward by the biasing force of the compression coil spring 60 and the rotor presser 72. The upper surface of the valve shaft holder 30 (the ceiling portion 32) is in contact with the lower surface (flat surface) of the rotor retainer 72.

  Also, the push nut 71 fixed to the upper end portion of the valve shaft 10 moves the valve shaft holder 30 excessively upward relative to the guide bush 20 during operation, and the fixing screw portion 23 of the guide bush 20 and the valve In order to prevent the threaded engagement with the movable screw portion 33 of the shaft holder 30, a return spring 75 made of a coil spring that biases the valve shaft holder 30 toward the guide bush 20 is provided.

  In the motor-operated valve 1 according to the present embodiment, for example, the valve body 14 is at the lowest position (origin) in order to prevent the valve body 14 from biting into the valve seat portion 46a and to ensure controllability in a low flow rate region. A gap of a predetermined size is formed between the valve body 14 and the valve seat portion 46a, and is formed between the straight portion 14s of the valve body 14 and the straight portion 46s of the valve port 46. A fluid such as a refrigerant flows through the gap (opening area).

  In the motor-operated valve 1 having such a configuration, when the rotor 51 is rotated by energizing and exciting the stator 52 (the stator coil 52c), the valve shaft holder 30 and the valve shaft 10 are rotated integrally therewith. At this time, the valve shaft 10 is moved up and down with the valve body 14 by the screw feeding mechanism 28 composed of the fixed screw portion 23 of the guide bush 20 and the movable screw portion 33 of the valve shaft holder 30, thereby the valve body 14. The clearance (lift amount, valve opening) between the valve seat 46a and the valve seat 46a is increased / decreased to adjust the flow rate of fluid such as refrigerant (see FIG. 7). Further, when the movable stopper body 34 of the valve shaft holder 30 and the fixed stopper body 24 of the lower stopper 25 fixed to the guide bush 20 come into contact with each other and the valve body 14 is at the lowest position (the lift amount of the valve body 14 is Even at 0), a gap is formed between the valve body 14 and the valve seat 46a, and a predetermined flow rate (0 pulse flow rate) is provided between the straight portion 14s of the valve body 14 and the straight portion 46s of the valve port 46. ) Is secured (see FIG. 7).

  By the way, in the motor-operated valve 1 of the present embodiment, the opening area (ring-shaped channel cross-sectional area) defined between the straight portion 14 s of the valve body 14 and the straight portion 46 s of the valve port 46 is the valve body 14. Passes through the valve port 46 (specifically, when the valve body 14 moves up and down the inside of the valve port 46 and the valve body 14 is at the highest position, the tip (lower end) of the valve body 14). Is positioned above the upper end of the valve port 46 (here, the valve seat 46a) (when exiting from the valve port 46) and viewed from a cross section perpendicular to the ascending / descending direction, the valve port 46 ( The inner surface of the valve element 14 and the outer surface of the valve element 14 (the outer surface of the valve element 14). Due to the opening area between the straight portion 46s, the above-mentioned low flow rate region It is adapted to perform flow control.

Here, “minute flow rate” is realized in the range where A2 / A1 is 0.056D ⁻² or less (A2 / A1 ≦ 0.056D ⁻² ) as shown in FIG. (In other words, the necessary flow rate can be ensured). D [mm] is the inner diameter of the straight portion 46s of the valve port 46 (that is, the diameter of the valve port 46), and A1 [mm ² ] is the opening area of the straight portion 46s of the valve port 46 (that is, A1 = πD). ^{2/4), A2 [mm} 2] , the aperture area being defined between the straight portion 46s of the straight portion 14s and the valve port 46 of the valve body 14 (i.e., the outer diameter of the straight portion 14s of the valve body 14 When (diameter) is d, A2 = π (D ² −d ² ) / 4).

Further, in the above range, when D <1.0, the flow rate change is large with respect to the channel cross-sectional area ratio (A2 / A1) (that is, the curve slope of 0.056D- ² becomes steep), and D> 2. .5, the change in flow rate is small with respect to the channel cross-sectional area ratio (A2 / A1) (that is, the curve slope of 0.056D- ² becomes gentle), and D <1.0 and D> 2.5. In the range, the flow rate control becomes difficult (controllability decreases). Therefore, the control of the “micro flow rate” is performed in a range where the inner diameter of the straight portion 46s of the valve port 46 (the diameter of the valve port 46) is 1.0 mm or more and 2.5 mm or less (1.0 ≦ D ≦ 2.5) ( This is performed in a region indicated by diagonal lines in FIG.

  However, in the motor-operated valve 1 that performs minute flow control as described above, as described above, the straight portion 46s of the valve port 46 provided in the valve seat 45 and the straight portion 46s of the valve port 46 according to the lift amount. Since the gap between the straight portion 14s of the valve body 14 inserted into the valve body 14 is set to be small (narrow), the energy loss of the fluid flowing (passing through) the valve port 46 is increased in the low flow rate control region, and consequently There was a risk that the flow rate variation would increase.

  Therefore, in the motor-operated valve 1 of the present embodiment, the following measures are taken in order to reduce the flow rate variation as described above.

  That is, in the motor-operated valve 1 according to the present embodiment, when the valve body 14 is at the lowest lowered position (origin position), the amount of lap in the ascending / descending direction between the straight portion 46s of the valve port 46 and the straight portion 14s of the valve body 14 is increased. (Overlapping amount) L is set to 0.05 mm or more and 0.4 mm or less. When the wrap amount L is less than 0.05 mm, which is the amount of screw play of the screw feed mechanism 28 (between the fixed screw portion 23 and the movable screw portion 33), the controllability in the low flow rate control region is improved. There is a possibility that it cannot be secured. Further, when the lap amount L is larger than 0.4 mm, as described based on the Darcy Wisebach equation, the Colebrook empirical equation, and the Kalman-Niclase empirical equation, the flow rate variation increases and the low flow rate is increased. It may be difficult to ensure controllability after the control range.

  In the motor-operated valve 1 of the present embodiment, the surface roughness Rz of the straight portion 46s of the valve port 46 and the straight portion 14s of the valve body 14 is 5.7 μm or less, more specifically, 1.4 μm or more, in addition to the above configuration. And it is set to 5.7 μm or less. When the surface roughness Rz is less than 1.4 μm, for example, it is difficult to realize by cutting, and there is a possibility that the variation of the tube friction coefficient λ (and hence the energy loss ΔE) becomes large. In addition, when the surface roughness Rz is larger than 5.7 μm, as described based on the Darcy-Weissbach equation, the Colebrook empirical equation, and the Kalman-Niclase empirical equation, the flow rate variation may increase.

When the surface roughness Rz is set to 1.4 μm or more and 5.7 μm or less, the diameter φD of the valve port 46 (straight portion 46s) is 1.0 mm or more and 2.5 mm or less. The roughness Rz / D is 5.6 × 10 ⁻⁴ or more and 5.7 × 10 ⁻³ or less.

  As described above, in the motor-operated valve 1 of the present embodiment, when the valve body 14 is at the lowest lowered position (origin position), the straight portion 46s of the valve port 46 corresponding to the pipe length L and the straight portion 14s of the valve body 14 are moved up and down. The lap amount (overlap amount) L in the direction is 0.05 mm or more and 0.4 mm or less, which is as small as possible within the valve opening pulse setting range, and the surfaces of the straight portion 46 s of the valve port 46 and the straight portion 14 s of the valve body 14 By setting the roughness Rz to 5.7 μm or less, more specifically 1.4 μm or more and 5.7 μm or less, which can be achieved by cutting, for example, the roughness Rz can be reduced without making major modifications to the conventional one. The energy loss of the fluid flowing through the valve port in the flow rate control region can be stabilized at a low value, and the controllability can be improved by suppressing the variation in the flow rate.

  In the above-described embodiment, the curved surface portion 14b of the valve body 14 has a plurality of inverted frustoconical tapered surface portions (upper tapered surface portion 14ba and lower tapered surface portion 14bb) whose control angle is gradually increased toward the distal end side. However, the present invention is not limited to this, and it may be configured by a tapered surface portion formed of a single inverted frustoconical surface. For example, an equal percentage characteristic or a characteristic approximate thereto may be obtained as a flow characteristic. It may be configured by an elliptical surface portion whose curvature is continuously increased as it approaches the tip, or a combination of the elliptical surface portion and one or a plurality of steps of an inverted frustoconical tapered surface portion. Of course.

  Moreover, in the said embodiment, in order to simplify a structure, the valve opening 46 is formed only by the straight part 46s which consists of a cylindrical surface, and the diameter (phi) D of the valve opening 46 (straight part 46s) is constant (in the raising / lowering direction). However, the shape of the valve port 46 is not limited to this.

  For example, as shown in FIG. 4, the valve port 46 is connected to the lower side of the valve seat 46 a, and is connected to the straight part 46 s having a cylindrical surface (the inner diameter is constant in the ascending / descending direction) and the lower side of the straight part 46 s. Further, it may have an enlarged diameter portion 46c having a truncated cone surface whose inner diameter (caliber) is continuously increased toward the lower side. In this case, the straight portion 46 s is the narrowest portion in the valve port 46 (the portion having the smallest diameter in the valve port 46), the inner diameter of the straight portion 46 s is the diameter of the valve port 46, and the straight portion in the valve port 46 The diameter (inner diameter) of the lower side (expanded portion 46c) of 46s is made larger than the diameter (inner diameter) of the straight portion 46s.

  Further, in this case, when the valve body 14 is in the lowest lowered position (origin position), the lower end portion of the straight portion 46s of the valve port 46 is the same position as or higher than the lower end portion of the straight portion 14s of the valve body 14. (In other words, the lower end portion of the straight portion 14s of the valve body 14 is positioned below the lower end portion of the straight portion 46s of the valve port 46), and the straight portion 14s of the valve body 14 and the valve Lapping amount (overlapping amount) L in the ascending / descending direction with the straight portion 46s of the port 46 (that is, the length in the ascending / descending direction of the straight portion 46s of the valve port 46 in this example) is 0.05 mm or more and 0.4 mm or less. You may set the dimension shape of each part so that it may become.

  With the configuration shown in FIG. 4, in addition to obtaining the same operational effects as the above embodiment, the lower end portion of the straight portion 46 s of the valve port 46 is connected to the lower end portion of the straight portion 14 s of the valve body 14. Since it is positioned at the same position or above, foreign matter (metal powder, shavings, abrasive, sludge, etc.) is sandwiched in the gap between the straight portion 14s of the valve body 14 and the straight portion 46s of the valve port 46 ( Deterioration of controllability and valve malfunction due to biting can be suppressed. In addition, since the lap amount L in the ascending / descending direction between the straight portion 14s of the valve body 14 and the straight portion 46s of the valve port 46 is defined only by the straight portion 46s (the length in the ascending / descending direction) of the valve port 46, It is also possible to suppress dimensional variations in the wrap amount L.

  Further, for example, as shown in FIG. 5, the valve port 46 is perpendicular to the straight portion 46s on the lower side of the straight portion 46s, instead of the enlarged-diameter portion 46c formed of the truncated cone surface shown in FIG. A step surface portion (terrace surface portion) 46 d having an annular flat surface is continuously provided, whereby the diameter (inner diameter) on the lower side (step surface portion 46 d) of the straight portion 46 s in the valve port 46 is changed to the diameter of the straight portion 46 s. It may be made larger than (inner diameter).

  Needless to say, the configuration shown in FIG. 5 can provide the same effects as those described with reference to FIG.

  Further, for example, as shown in FIG. 6, the valve seat 45 is chamfered (beveled portion 46 e) having an inverted truncated cone surface above the straight portion 46 s (in other words, between the valve seat 46 a and the straight portion 46 s). Needless to say, or R processing may be applied.

  Further, in the above-described embodiment, when the valve body 14 is in the lowest lowered position (origin position), a valve-closing-type electric type in which a gap of a predetermined size is formed between the valve body 14 and the valve seat 46a. Although the valve 1 has been illustrated and described, the present invention is, for example, above the straight portion 14s of the valve body 14 (in other words, between the lower small diameter portion 13 of the valve shaft 10 and the straight portion 14s of the valve body 14). When the valve body 14 is in the lowest lowered position (origin position), the valve body 14 (the seating surface section 14a) is located in the valve seat. Needless to say, the present invention can also be applied to a valve-closed electric valve seated on 46a (see FIG. 8).

DESCRIPTION OF SYMBOLS 1 Motorized valve 10 Valve shaft 14 Valve body 14a Seating surface part 14b Curved surface part 14ba Upper taper surface part 14bb Lower taper surface part 14s Straight part (Valve body side straight part)
20 Guide bush 21 Cylindrical part 23 Fixing screw part (Male thread part)
28 Screw feed mechanism 29 Lower stopper mechanism 30 Valve shaft holder 33 Movable screw part (female screw part)
40 valve body 40a valve chamber 41 first opening 41a first conduit 42 second opening 42a second conduit 45 valve seat 46 valve port 46a valve seat 46c enlarged diameter portion 46d stepped surface portion 46e chamfered portion 46s straight portion (valve port side straight portion) )
47 bowl-like plate 50 stepping motor 51 rotor 52 stator 55 can 60 compression coil spring 70 retaining member

Claims (11)

A valve body having a valve port and a valve chamber into which fluid is introduced and led through the valve port, and a valve body that changes a flow rate of the fluid flowing through the valve port according to a lift amount;
The valve port is provided with a valve port side straight portion made of a cylindrical surface, and the valve body is inserted into the valve port side straight portion according to a lift amount, and has a constant outer diameter in the up and down direction and the valve port An electric valve provided with a valve body side straight portion having a smaller diameter than the side straight portion,
At the lowest lowered position of the valve body, the lap amount in the ascending / descending direction of the valve port side straight portion and the valve body side straight portion is set to 0.05 mm or more and 0.4 mm or less,
The motor-operated valve, wherein a surface roughness Rz of the valve-portion-side straight portion and the valve-body-side straight portion is set to 5.7 μm or less. At the lowest lowered position of the valve body, the lower end portion of the valve port side straight portion is positioned at the same position as or above the lower end portion of the valve body side straight portion, and
2. The motor-operated valve according to claim 1, wherein a diameter of the lower side of the valve port side straight portion of the valve port is larger than a diameter of the valve port side straight portion.   On the lower end side of the valve port side straight portion, there is an enlarged diameter portion made of a truncated cone surface having an inner diameter larger than that of the valve port side straight portion, or an annular flat surface perpendicular to the valve port side straight portion. The motor-operated valve according to claim 2, wherein stepped surface portions are continuously provided.   The motor-operated valve according to any one of claims 1 to 3, wherein a length of the valve body side straight portion in the ascending / descending direction is set to 0.05 mm or more and 0.5 mm or less. An inner diameter of the valve port side straight portion is defined as D [mm], an opening area of the valve port side straight portion is defined as A1 [mm ² ], and is defined between the valve port side straight portion and the valve body side straight portion. The opening area is set to 1.0 ≦ D ≦ 2.5 and A2 / A1 ≦ 0.056D ⁻² with A2 [mm ² ], according to any one of claims 1 to 4. The motorized valve described.   The opening area defined between the valve-portion-side straight portion and the valve-body-side straight portion is such that, when the valve body passes through the valve port, the valve port is viewed in a cross section perpendicular to the ascending / descending direction. The motor-operated valve according to claim 5, wherein the motor-operated valve is a minimum area of an opening area defined between the valve body and the valve body.   The motor-operated valve according to any one of claims 1 to 6, wherein the valve-portion-side straight portion is a narrowest portion of the valve-port.   8. A curved surface portion, which is continuously or stepwise increased as the curvature or control angle approaches the distal end, is connected to the distal end side of the valve body-side straight portion in the valve body. The motor operated valve according to any one of the above.   The motor-operated valve according to claim 8, wherein the curved surface portion has a tapered surface portion including a single-stage or a plurality of stages of inverted truncated cone surfaces.   The motor-operated valve according to claim 8, wherein the curved surface portion is designed so as to obtain an equal percent characteristic or a characteristic approximate thereto as a flow characteristic.   The motor-operated valve according to any one of claims 1 to 10, further comprising a can provided in the valve body and a stator externally mounted on the can.

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