VALVE

Abstract: A valve comprising a rotor (4) which rotates at a fixed position within a tubular flowpassage (l). A rotating magnetic field generating means (2) is fixedly positioned around the rotor (4). A first screw means (6) is rotated coaxially with the rotor means together with the latter. A second screw means (8) engages the first screw means (6) and is movable in an axial direction of the screw (6) without being rotated in itself by the rotation of the first screw means. A valve body (7) is connected to the second screw means (8). A valve seat l0 is engagable by the valve body means, whereby when the rotor (4) is rotated by the action of the rotating magnetic field generated by the rotating magnetic field generating means (2), said rotation causes the second screw means (8) to be moved in an axial direction of the screw (6), the latter movement being transmitted to the valve body (7) to adjust the degree of opening and closing of the valve.

Description: This invention relates to valves. More specifically, the present invention relates to a valve having a valve body which is operated by a turning force produced by means of an electromagnetic force and which is not mechanically operated by an external source via a sliding seal portion provided therein, such as a gland packing and mechanical seal. Actuators for the valves usually require a considerable space in a piping system assembly. In the case where equipments and piping systems need to be assembled as compactly as possible, it is desirable for the space occupied by the actuator for the valve to be made as small as possible. Not only opening and closing a flowpassage but accurate flow-rate adjusting function is required for such valves. It is an object of this invention to provide a valve in which a valve body is powerfully operated utilizing a screw mechanism, but in which the structure provided outside the tubular passage or piping line is reduced to a minimum. In accordance with the present invention, there is provided a valve comprising a rotor which can rotate at a fixed position within a tubular flowpassage means (l), rotating magnetic field generating means (2) fixedly positioned around said rotor means (4), a first screw means (6) which is rotated coaxially with the rotor means (4) together with the latter, a second screw means (8) which engages the first screw means (6) and is movable in an axial direction of the screw without being rotated in itself by the rotation of the first screw means (6); valve body means (7) connected to the second screw means (8); and valve seat means (l0) engagable with the valve body means (7), whereby when the rotor means (4) is rotated by the action of rotating magnetic field generated by the rotating magnetic field generating means (2), said rotation causes the second screw means (8) to be moved in an axial direction of the screw (6), said movement being transmitted to the valve body (7) to adjust the degree of opening and closing of the valve. The tubular flowpassage of the valve according to the present invention may have an outside diameter which is the same as that of a tubular passage to be connected so that the external appearance thereof corresponds substantially to a part of the tubular passage of a piping system, or is of outside diameter slightly larger than that of the tubular passage, or is freely selected to be smaller than the outside diameter or slightly larger than that of the tubular passage. One or more rotors or electric motors by which the valve body is actuated to control the degree of opening of the valve are installed in the tubular flowpassage. If a plurality of such rotors or motors are provided, they are normally disposed coaxially. The rotor is located in the tubular flowpassage so that the rotor itself tends to obstruct the flow of fluid. In order to minimize the aforesaid obstruction, the rotor is provided with fluid-passing portions which are as large as possible and as many as possible to allow the fluid to pass through. Likewise, also in the case where the motor is fixed in the tubular flowpassage, it is naturally necessary to enlarge the cross-sectional projected areas through which area the fluid passes, by selecting a motor which allows one to make smaller the cross-sectional projected area of both of the motor and a fixing element which fixes the motor in the tubular flowpassage, which area obstructs the flow of fluid. Considering the cases in which the rotor is in rotation and at rest, the fluid passing portion provided in the rotor, i.e. a cutout hole or the like which allows the fluid to pass through it, may be normally designed so as to allow the fluid to pass through the portion in the same direction as the fluid flow through the tubular passage of the valve, or may be designed so as to allow the fluid to pass through the portion in a direction inclined with respect to the fluid flow through the tubular passage of the valve as required. The shape of the cross-sectional area of the fluid passing portion is selected taking into consideration the mechanical strength of the rotor. In the gap between the outer periphery of the rotor and the inner wall surface of the tubular flow-passage, a longitudinal slot portion may be provided on the outer periphery of the rotor or on the inner wall surface of the tubular flowpassage to reduce the flow resistance to fluid at a portion where the rotor is installed. This means for reducing the flow resistance may be used also for the aforesaid fluid passing portion. A desired number of rotors are secured to one and the same rotational shaft, and likewise, for the motor, the desired number of rotors and stators are juxtaposed, to produce the turning force as required. A combination of a rotor and rotating magnetic field generating means or an electric motor both of which constitute a pulse motor or A.C. servo motor constitutes a preferred valve body driving power source. The combination of a rotor and a rotating magnetic field generating means, and an electric motor may be hereinafter collectively called "a motor assembly". The rotational shaft of a rotor or a motor may have a mechanical or electric brake system attached thereto to stop the rotation thereof as needed. The rotational shaft of a rotor or a motor and a valve function portion, comprising a valve body and a valve seat, may be positioned in the centre of the tubular flowpassage or may be positioned eccentrically. Where a rotor is used for a large-size valve, the angle of a rotational shaft having first screw means with respect to a flow direction of fluid is selected according to the position of the rotating magnetic field generating source or rotating magnetic field generating means for driving the rotor, and to a direction changing mechanism adopted for the fluid. Similarly, the direction of the rotational shaft having the first screw means of the motor can be inclined at a suitable angle with respect to the flow direction of the fluid. The rotor or motor may be positioned at upstream, downstream or both sides with respect to a valve body and a valve seat of a valve according to this invention. In the case where the rotor or motor is positioned at both sides, the upstream and downstream rotors or the like work together to actuate the valve body. To locate the rotor in the tubular flowpassage of the fluid, one or more fixing elements for the rotor bearing means are provided on the inner wall of the tubular flowpassage. These may be roller bearings or sliding bearings. On the other hand, in the case where the tubular flowpassage is small in diameter or where as desired, more than one bearing track for bearing the outer periphery of the rotor to allow the rotor to rotate can be provided to form the rotor bearing means on the inner wall surface of the tubular flowpassage. For the engagement between the outer periphery of the rotor and the bearing track, a roller bearing may be employed; and where the surface of the bearing track or the like is covered with a high polymer material which can present a surface having a low coefficient of friction, or where the fluid passing through the valve has a lubricating ability, the sliding bearing by which the surface of the outer periphery and the surface of the bearing track slide each other may be employed. A desired number of rotating magnetic field generating sources for driving the rotor can be provided within the tubular flowpassage, on the inner wall surface, in the wall constituting the tubular flowpassage or on the outer surface of said wall. The magnetic field generating source is preferably covered so as to have the required resistances such as corrision resistance, heat resistance, erosion resistance, wear resistance, etc., and may be fixed within the tubular flowpassage or on the inner wall surface or may be embedded into the wall; further, the source is provided externally of or within the wall of the tubular flowpassage with a magnetic field generating capacity enough to impart the required turning force to the rotor. The provision of the rotational magnetic field producing means externally of the wall of the flowpassage or in the wall is preferable in that there is no need for taking the corrosion, erosion, or wear of said means caused by the fluid into consideration. The former is preferable as being simple in construction. Where the magnetic field generating means is embedded into the wall of the tubular flowpassage or is provided externally of the wall of the tubular flowpassage, a cooling function element may be attached thereto as needed. Partitioning wall material used to form a pipeway or a tubular flowpassage is suitably selected from conventional metal or non-metal materials, that is, high polymer material, ceramics material and the like. Where the rotating magnetic field generating device is provided externally of the tubular passage partitioning wall or in the same, that is, where the tubular flowpassage wall is interposed between the magnetic field generating source for actuating the valve and the rotor, material for the partitioning wall to form a tubular flowpassage is desirably a material having a magnetic permeability which is as large as possible. The position of the magnetic field generating source is determined according to the position and direction of the rotation axis of the rotor positioned in the tubular flowpassage. One or more valve bodies are coupled through sliding screws, ball screws or the like to the rotor itself, the rotational shaft of the same, the rotational shaft of the motor or the rotational shaft mechanically coupled to the rotational shaft of the rotor. The valve body is rectilinearly displaced by the rotation of the rotor itself or the rotational shaft of the rotor or the like through the sliding screw or ball screw, or actuated by the forward and backward moving shaft of a transmission mechanism connected to the rotor. In the case where the torque of the rotor or motor is small, or where the displacement of the valve body with respect to the degree of rotation of the rotor or motor is reduced to enhance the ability for fine adjustment of flow rate, the transmission mechanism with various gears and other turning force transmission mechanical elements is coupled to the rotational shaft of the rotor or motor so that the rotational shaft or the forward and backward moving shaft for driving the valve body may be actuated. On the other hand, the motor assembly in the present invention may include a stopping motor. The valve of the present invention may be any of normal globe valve, needle valve, sluice valve, cage valve, etc. One or more valve seats which engage with the valve body or allow the valve body to fit in to constitute a valve are provided in the tubular flowpassage. The valve seat is provided in the tubular flowpassage of the fluid or at the end of the tubular flowpassage according to the action of the valve body. The valve body may be disposed in such a manner that, to open the valve, the valve body is disengaged from the valve seat located at one end or both ends of the tubular flowpassage of the valve and shifted outwardly of the tubular flowpassage of the valve. The axis common to a valve and its valve seat may not be on the same straight line which is the axis of rotation shaft of the motor or the like, and the plane of the valve seat opening may not be perpendicular to the flow direction of the fluid through the tubular passage of the valve of the present invention, because the valve body can be moved forward or backward by transmitting the rotation of the rotating shaft of the rotor or motor, through a universal joint, flexible shaft, or transmission mechanism utilized between the rotating shaft and the valve body, to valve body side end rotating rod with external thread which engage with the bore of the valve body having a sliding screw or ball screw of internal thread or with worm wheel connected to the valve body. In order to adapt the flow characteristics (degree of valve opening vs. flow rate) of the valve related to the size, shape or others of the valve body and the valve seat to be desired flow regulation characteristics of a flowpassage system in which the valve is used, the number of poles of the magnetic field generating source, and mechanical and geometrical structural shape of the same may be varied. The position and magnitude of voltage and current applied to each of the magnetic field producing sources may be varied corresponding to the wave form and frequency of voltage and current applied and to the geometrical position of each magnetic field generating source whereby the rotational speed and turning force of the rotor or the like may be varied. To control the operating condition of the valve body as required, the voltage and current applied to the magnetic field generating source may be any of the pulse voltage and current AC, and DC. The rotor means rotated by the rotating magnetic field generated by the rotating magnetic field generating means may be of a magnetic material represented by pieces of iron or magnets, or a conductive material such as metal which internally generates an eddy current by means of an external magnetic field. The type which encases a conductive member such as a metal member constituting a coil to which voltage and current are not applied may be employed. For detection of the rotational speed and the number of rotations of the rotor to detect the position of the valve body, a pick-up coil, a photo-electric switch, Hall element, Hall integrated circuit, magnetic reluctance element, Wiegant effect element, or magnetic transistor may be used. To detect the position itself of the valve body including the case when the valve is totally opened and totally closed, a differential transformer, resolver, encoder, limit switch, reed seitch, piezo-electric switch, photo-electric switch, torque switch or the like may be used. The rotor or motor of the valve according to the present invention may be secured to the desired position in the tubular flowpassage for operation, and the distance from the valve body and the valve seat is selected as required. A flexible rotational shaft and its bearing means may be used to transmit the turning force of the rotational shaft of the rotor or the like to allow the presence of a bend of a flowpassage as far as the valve body and the valve seat. Where plural sets of valve bodies and valve seats are provided in one valve of this invention, a branch discharging opening may be provided in a flowpassage between each set of valve body and valve seat so that a multi-direction (more than three directions) valve may be formed. To allow the valve of this invention to possess a check valve function, a valve body and a valve seat for the check valve may be provided at a suitable position in the valve. While normally the tubular flowpassage in the present invention for the fluid has a circular cross section, it is to be noted in the valve of this invention that as needed, the tubular flowpassage for the fluid may not be circular, but may be oval, triangle, square, or in other polygon form in cross section, particularly when the rotating magnetic field generating means is disposed in the space within the tubular flowpassage. A hollow annular body encasing a fluid therein may be provided in the valve seat and fluid pressure within the annular body being detected and controlled to make smooth the access and contact of the valve body to the valve seat when the valve is closed to enhance the sealing properties after the contact. A labyrinth function portion may be provided on either or both of the valve body and valve seat for the purpose of enhancing the tightness of the seal, etc. The invention is described further hereinafter, by way of example only, with reference to the accompanying drawings, in which:- Figs. l to 6 respectively show diagrammatic longitudinal sectional views of a plurality of valves according to the present invention; and Fig. 7 is a diagrammatic view for explaining the structure of part of the embodiment of Fig. 6. In these Figures, the arrows indicated by bold lines show flow direction of the fluid. Fig. l shows a first example in which this invention is applied to a needle valve. A group of coils 2 for generating a rotating magnetic field are disposed so as to surround a portion of the outside of a wall l of a tubular flowpassage having a circular cross-section. A rotor 4 supported and positioned by means of two fixing elements 3 within the tubular flowpassage is rotated according to the direction, voltage, frequency and waveform of current supplied to the group of coils 2, for adjustment of the degree of opening of the needle valve. An externally threaded portion 6 positioned on one end of a shaft 5 of the rotor 4 is engaged with an internally threaded portion 8 formed in a valve body 7 to constitute a sliding screw thread portion of the valve. By rotation of the rotor 4, the sliding screw thread portion functions together with a guide plate 9 which is secured to the wall l in order to allow the valve body to move longitudinally while preventing the rotation of the valve body 7, whereby to cause the valve body 7 selectively to engage and disengage from a valve seat l0 depending upon the direction of rotation of the rotor 4. Fig. 2 shows a second example of a needle valve which is operated when the rotor 4 is rotated, wherein the rotor is supported by bearing balls which roll on a bearing track portion ll of the inner surface of the wall l, thereby eliminating the fixing elements 3 of Fig. l. Fig. 3 shows a valve of the type which can be mounted on a dam wall or the like and is suitable for use as a water discharge valve, wherein a valve seat l0 is located at the end of a tubular flowpassage so that, when the valve is open, the valve body 7 lies outwardly of the tubular flowpassage of the valve. Fig. 4 shows a further example of a needle valve in which an internally threaded rotor 4 is threadedly engaged with an actuating or propelling shaft of a valve body 7 which shaft is externally threaded. Fig. 5 shows an example of a sluice valve comprising two valve seats l0, and a valve body 7 having two functional portions. As in the case of the Figs. 4 and 5 examples, the rotation of the valve body 7 is prevented by suitable means similarly to Fig. l and the like. Fig. 6 shows a fourth example of a needle valve in which a set of a group of coils 2 and a rotor 4 is provided as one unit of an electric motor l3 within a tubular flowpassage. A passage l2 formed through a fixing element 303 of the motor may be used both for electric wiring and for introducing and discharging a cooling medium for the motor. This motor l3 may house therein the construction illustrated with Fig. l for example, as will be understood from Fig. 7, thereby eliminating the provision of a sliding sealing portion. An annular space 202 which houses therein a group of coils 2 for producing a rotating magnetic field communicates with the exterior of the outer wall l through the passage l2 while the space within a cylindrical casing l0l communicates with a flowpassage inside the wall l but does not communicate with the exterior of the wall l. A stator 200 ensures that the space 202 is closed against entry of the fluid. The example illustrated in Fig. 6 is an example in which a rotating magnetic field generating source is disposed in a space within the tubular flowpassage.

Claims: 1. A valve characterised by a rotor means (4) which can rotate at a fixed position within a tubular flowpassage means (l), rotating magnetic field generating means (2) fixedly positioned around said rotor means (4), a first screw means (6) which is rotated coaxially with the rotor means (4) together with the latter, a second screw means (8) which engages the first screw means (6) and is movable in an axial direction of the screw without being rotated in itself by the rotation of the first screw means (6); valve body means (7) connected to the second screw means (8); and valve seat means (l0) engagable with the valve body means (7), whereby when the rotor means (4) is rotated by the action of rotating magnetic field generated by the rotating magnetic field generating means (2), said rotation causes the second screw means (8) to be moved in an axial direction of the screw (6), said movement being transmitted to the valve body (7) to adjust the degree of opening and closing of the valve. 2. A valve according to claim l, wherein the rotating magnetic field generating means (2) is disposed on the outer surface of the tubular flowpassage means (l). 3. A valve according to claim l, wherein the rotating magnetic field generating means (2) is disposed within the inner surface of the tubular flowpassage means (l). 4. A valve according to claim l, wherein the position of the rotor means is fixed by means of bearing track means provided on the inner surface of the tubular flowpassage means. 5. A valve according to claim l, wherein the rotor means has rotational shaft means, said rotational shaft means being supported by bearing means provided within the tubular flowpassage means whereby the longitudinal position of the rotor means is fixed.

Inventors: FUJITA, YUICHI, KANEKO, TAKAYUKI, NUMAGUCHI, TOHRU, OKADA, MITSUO, SHIMA, KAZUMI, YANARU, HIDEAKI
Applicants: TOYO ENGINEERING CORPORATION
Application year: 1987
Main classification: F16K31
IPC codes: F16K31, F16K1