JP2013011186A - Uniaxial eccentric screw pump - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a uniaxial eccentric screw pump follow-up rotating a stator in the number of rotations half of a rotor with a rotation force, which follow-up rotates the stator by keeping a correct phase relationship, even when a rising accelerating time at the start is shortened.SOLUTION: The stator 41 of the uniaxial eccentric screw pump 1 has a structure to have an elastomer part 41g having its female screw shaped inner surface, formed in a constant thickness.

Description

  The present invention relates to a uniaxial eccentric screw pump for quantitatively feeding viscous liquids such as food raw materials, chemical raw materials, and sewage sludge, and in particular, technology for maintaining an accurate phase relationship between the rotor and the stator of this type of uniaxial eccentric screw pump. About.

  As this type of single-shaft eccentric screw pump, for example, a technique disclosed in Patent Document 1 is disclosed. The uniaxial eccentric screw pump described in the document has a rotatably supported stator having an inner surface of a female thread. As in the stator 141 illustrated in FIG. 5, this type of stator includes a cylindrical support portion 141 h and an elastomer portion 141 g having a female screw-like inner surface molded on the inner peripheral surface of the support portion 141 h. Yes. As shown in FIG. 6, a male screw-like spiral portion of the rotor 142 is inserted into the stator 141 and the base end portion of the rotor 142 is connected to a drive portion (not shown). As shown in FIG. 7, the rotation axis L2 of the rotor 142 is arranged eccentrically by a predetermined distance with respect to the rotation axis L1 of the stator 141, and when the rotor 142 is rotated as shown in FIGS. The stator 141 is configured to follow and rotate at half the rotational speed of the rotor 142 by the rotational force. In FIG. 6, symbol R <b> 1 indicates an image of the rotation angle of the rotor 142, and symbol R <b> 2 indicates an image of the rotation angle of the stator 141 that rotates following the rotation angle of the rotor 142.

WO2010 / 103993 A1

  However, in the uniaxial eccentric screw pump having such a configuration, the outer peripheral surface of the elastomer portion 141g is cylindrical, whereas the inner peripheral surface has a female screw shape, so that the thickness along the axial direction is small. It is uneven. Therefore, if the stator having this elastomer portion is rotated following the rotation of the rotor, the rotor drive motor will start when the full-voltage start (direct start) is performed (or when inverter control or servo control is performed). If the impact at the start when transmitting the rotational force from the stator to the stator is large, the elastomer part of the stator will be elastically deformed unevenly by the impact at the start. Therefore, especially when the startup acceleration time at start-up is shortened, the stator cannot follow the rotation of the rotor uniformly in the entire axial direction, and as a result, as in the examples shown in FIGS. In this state, the non-following state (in these drawings, the seal line between the rotor 142 and the stator 141 is broken, so that the contour lines on the drawings cross each other). In such a non-following state, the original accurate phase relationship between the rotor 142 and the stator 141 cannot be maintained, and in an extreme case, the rotor 142 may idle in the stator 141.

  Therefore, the present invention has been made paying attention to such a problem, and in a single-shaft eccentric screw pump that rotates the stator at a half rotation speed of the rotor by the rotational force of the rotor, It is an object of the present invention to provide a uniaxial eccentric screw pump capable of rotating a stator following a precise phase relationship with a rotor even when a rising acceleration time is shortened.

  In order to solve the above-described problems, the present invention is directed to a rotatably supported stator having a female screw-shaped inner surface, a male screw-shaped spiral portion inserted in the stator, and a linear base end portion for driving a motor. A rotor directly connected to a shaft, and the rotation axis of the rotor is arranged eccentrically by a predetermined distance with respect to the rotation axis of the stator, and the stator is half of the rotor by the rotational force of the rotor. A uniaxial eccentric screw pump configured to rotate following rotation at a rotational speed, wherein the stator has an elastomer portion in which the inner surface of the female screw is formed with a constant thickness.

  According to the uniaxial eccentric screw pump according to the present invention, in the uniaxial eccentric screw pump that rotates the stator at a rotational speed that is a half of the rotor by the rotational force of the rotor, the stator has a constant thickness on the inner surface of the female screw. The elastomer part of the stator is uniformly elastically deformed by the impact at the start-up even if the impact at the start-up when transmitting the rotational force from the rotor to the stator is large. be able to. For this reason, the stator can follow the rotation of the rotor uniformly in the entire axial direction, whereby the original accurate phase relationship between the rotor and the stator can be maintained.

  Here, in the single-shaft eccentric screw pump according to the present invention, the stator includes a stator inner cylinder, and two stepped stator outer cylinders formed so as to sandwich the stator inner cylinder from both sides in the axial direction. It is preferable that the stator inner cylinder includes the elastomer part and a support part integrally formed so as to cover an outer peripheral surface of the elastomer part. Such a configuration is suitable for realizing a configuration having an elastomer portion in which the internal thread-shaped inner surface of the stator is formed with a constant thickness.

  Further, the support portion has flanges projecting in an annular shape toward the radially outer side at both ends thereof, and the elastomer portion is opposed to the stepped shape of the two stator outer cylinders, and the shaft of the flange If it is extended to both end surfaces in the direction, the elastomer portion of the flange portion performs a sealing function, so in realizing a configuration having an elastomer portion in which the internal thread-like inner surface of the stator is formed with a constant thickness. Is preferred.

  Furthermore, the two stator outer cylinders have screw portions that are screwed together at the ends facing each other, and the stator portions are cooperated with the stepped shape by closing the screw portions in the axial direction. If the inner cylinder is sandwiched from both sides in the axial direction, the stator inner cylinder can be securely sandwiched from both sides while easily adjusting the axial facing distance between the two stator outer cylinders. Further, it is more preferable to realize a configuration having an elastomer portion in which the internal thread-shaped inner surface of the stator is formed with a constant thickness.

  As described above, according to the present invention, even if the startup acceleration time at startup is shortened in the single-shaft eccentric screw pump that rotates the stator at the half rotation speed of the rotor by the rotational force of the rotor, The stator can be rotated following the rotor while maintaining an accurate phase relationship with the rotor.

BRIEF DESCRIPTION OF THE DRAWINGS It is a figure explaining one Embodiment of the uniaxial eccentric screw pump which concerns on this invention, In the same figure, sectional drawing along the axis line is shown. It is an enlarged view of the stator (stator inner cylinder) of the uniaxial eccentric screw pump which concerns on this invention, the figure (a) is sectional drawing along an axial direction, (b) is ZZ cross section in the figure (a). FIG. It is a figure ((a)-(l)) which shows the normal phase relationship of the stator which rotates with the rotation speed of 1/2 of the rotation angle of a rotor. It is a figure ((a)-(l)) which shows collectively the cross section of the axial direction corresponding to each phase relationship of FIG. 4, and the phase relationship in each cross section. It is an enlarged view which shows an example of the stator of the conventional uniaxial eccentric screw pump, The figure (a) is sectional drawing along an axial direction, (b) is XX sectional drawing in the figure (a). In a uniaxial eccentric screw pump provided with the conventional stator, it is a figure ((a)-(l)) showing phase relation when a stator shifts from a regular phase to a rotor by rapid starting. It is a figure ((a)-(l)) which shows the cross section of the axial direction corresponding to each phase relationship of FIG. 6, and the phase relationship in each cross section together.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings as appropriate.
As shown in FIG. 1, the uniaxial eccentric screw pump 1 has a screw pump unit 40. A casing 30 is provided on the suction side 14 of the screw pump unit 40. The casing 30 has a suction port 35 on its side surface (in this example, above the rotation axis L2). The housing 46 of the screw pump part 40 and the discharge side 14 (also the suction side of the screw pump part 40) of the casing 30 are detachably connected by a ferrule clamp 43. Further, the discharge portion 50 is mounted on the discharge side 46t of the housing 46 by a fastening screw 50a. A contact portion between the discharge side 46 t of the housing 46 and the discharge portion 50 is sealed by a seal member 52.

  And the bracket part 20 which incorporates the bearing part not shown with respect to the said casing 30 by the fastening screw not shown from the opposite side to the screw pump part 40 is connected, The base end side ( On the right side of the figure, a motor (not shown) is fixed. The bearing portion rotatably supports a middle portion of the drive shaft 8 by two rolling bearings separated in the axial direction, and the end surface of the drive shaft 8 on the casing 30 side is the underwater bearing 22 and the seal. The shaft is sealed by the member 24.

  Further, the screw pump section 40 includes a male threaded rotor 42 and a stator 41 having a female threaded inner surface in a cylindrical housing 46. The rotor 42 is composed of a spiral portion 42a on the distal end side and a linear base end portion 42b. The base end part 42b is directly connected to the front end of the drive shaft 8 that is disposed horizontally without using a universal joint. The spiral portion 42a has an oval cross section that is eccentric with respect to its own rotation axis L2, and this spiral portion 42a is inserted into a stator 41 that has a female screw-like inner surface. The rotation axis L2 of the rotor 42 is arranged eccentrically by a predetermined eccentric amount E with respect to the rotation axis L1 of the stator 41.

  The stator 41 has a female thread pitch twice that of the spiral portion 42 a of the rotor 42. Both ends of the stator 41 are rotatably supported in the housing 46 via annular self-lubricating bearings 47 and 48 as slide bearings. Here, in this example, the stator 41 includes a stator inner cylinder 41a and two stator outer cylinders 41b and 41c having a stepped shape formed so as to sandwich the stator inner cylinder 41a from both sides in the axial direction. Configured.

Further, as shown in FIG. 2, the stator inner cylinder 41a is formed integrally with an elastomer portion 41g in which a female screw-like inner surface is molded with a constant thickness and an outer peripheral surface of the elastomer portion 41g. The inner surface of the female screw is constituted by the inner peripheral portion of the elastomer portion 41g. Further, the support part 41g has flanges 41f projecting in an annular shape outward in the radial direction at both ends, and the elastomer part 41g is opposed to the stepped shape of the two stator outer cylinders 41b and 41c. The flange 41f extends to both end surfaces in the axial direction.
Further, as shown in FIG. 1, the two stator outer cylinders 41b and 41c have screw portions 41m and 41n that are screwed to each other at their opposite ends, and the screw portions 41m and 41n are arranged in the axial direction. By closing, the stator inner cylinder 41a is sandwiched from both sides in the axial direction in cooperation with the stepped shape.

  The casing 30 and the housing 46 are respectively formed with concave stepped portions on the inner surfaces on the sides facing each other. Further, convex step portions are formed on the outer peripheral surface of the stator 41 by the stator outer cylinders 41b and 41c, and the stator outer cylinders 41b and 41c are provided with self-lubricating bearings 47 at both ends of the convex step portions. , 48 are externally fitted in contact with each other, and the casing 30 and the housing 46 are assembled by the ferrule clamp 43 so that the inner surface of the concave step formed on the inner surfaces of the casing 30 and the housing 46 is the self-lubricating bearing 47. The stator 41 is rotatably supported while restraining the movement of the shaft 48 in the axial direction. As a result, the stator outer cylinders 41b and 41c and the stator inner cylinder 41a are fixed by the cooperation of the threaded portion and the stepped shape, and rotate as an integral stator 41 as a whole.

  In the uniaxial eccentric screw pump 1 having such a configuration, when the drive shaft 8 rotates integrally with the rotational force of the motor 2, the rotor 42 directly connected to the drive shaft 8 rotates. As shown in FIGS. 3 and 4, in the screw pump unit 10, the rotor 42 rotates about its rotational axis L2, and the stator 41 also has its rotational axis L1 as the spiral portion 12a of the rotor 12 moves. The pumped fluid is pumped from the suction port 12 toward the discharge port 16 by being driven and rotated at a half speed of the rotor 42 in synchronization with the rotation of the rotor 42 as the center.

Next, the operation and effect of this pumping device will be described.
This single-shaft eccentric screw pump 1 rotates the stator 41 by the rotational force of the rotor at half the rotational speed of the rotor 42, and the stator 41 has a female screw-like inner surface formed with a constant thickness. Since the elastomer portion 41g is included, even if the impact at the time of startup when the rotational force is transmitted from the rotor 42 to the stator 41 is large, the elastomer portion 41g of the stator 41 is evenly elastic by the impact at the time of startup. Can be deformed. Therefore, as shown in FIGS. 3 and 4, the stator 41 can follow the rotation of the rotor 42 uniformly over the entire axial direction, whereby the original accurate phase relationship between the rotor 42 and the stator 41 can be obtained. Can keep. That is, in FIGS. 3 and 4, the seal line between the rotor 42 and the stator 41 is correctly maintained, and the outer peripheral surface of the rotor 42 is in contact with the inner peripheral surface of the stator 41 without the contour lines on the drawings crossing each other. State is maintained. In FIG. 3, symbol R <b> 1 indicates an image of the rotation angle of the rotor 42, and symbol R <b> 2 indicates an image of the rotation angle of the stator 41 that rotates following the rotation angle of the rotor 42.

  Further, according to the uniaxial eccentric screw pump 1, the stator 42 includes a stator inner cylinder 41a and two stator outer cylinders 41b having a stepped shape formed so as to sandwich the stator inner cylinder 41a from both sides in the axial direction. 41c, and the stator inner cylinder 41a has an elastomer part 41g and a support part 41h formed integrally so as to cover the outer peripheral surface of the elastomer part 41g. This is suitable for realizing a configuration having an elastomer portion 41g having a female screw-shaped inner surface formed with a constant thickness.

  Further, according to the uniaxial eccentric screw pump 1, the support portion 41h of the stator inner cylinder 41a has flanges 41f projecting in an annular shape toward the radially outer side at both ends, and the elastomer portion 41g has two Since the stator outer cylinders 41b and 41c are opposed to the stepped shape and extend to both end surfaces in the axial direction of the flange 41f, the elastomer portion 41g of the flange 41f can perform a sealing function. Therefore, it is more preferable to realize a configuration having an elastomer portion 41g in which the internal thread-shaped inner surface of the stator 41 is formed with a constant thickness.

Further, according to the uniaxial eccentric screw pump 1, the two stator outer cylinders 41b and 41c have screw portions 41m and 41n that are screwed to each other at their opposite ends, and the screw portions 41m and 41n are connected to each other. Since the stator inner cylinder 41a is sandwiched from both sides in the axial direction by cooperating with the stepped shape of the two stator outer cylinders 41b and 41c by closing, the shafts of the two stator outer cylinders 41b and 41c are mutually connected. The stator inner cylinder 41a can be securely sandwiched from both sides while easily adjusting the opposing distance in the direction. Therefore, it is even more suitable for realizing a configuration having an elastomer part 41g in which the internal thread-shaped inner surface of the stator 41 is formed with a constant thickness.
The single-shaft eccentric screw pump according to the present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the spirit of the present invention.

DESCRIPTION OF SYMBOLS 1 Uniaxial eccentric screw pump 2 Motor 8 Drive shaft 14 Suction side 16 Discharge port 20 Bracket part 30 Casing 35 Suction port 40 Screw pump part 41 Stator 42 Rotor E Predetermined distance of eccentricity L1 Stator rotation axis L2 Rotor rotation axis

Claims (4)

A rotor having a female screw-like inner surface and rotatably supported; and a rotor in which a male screw-like spiral portion is inserted in the stator and a linear base end portion is directly connected to a drive shaft of a motor. The rotation axis of the stator is eccentric from the rotation axis of the stator by a predetermined distance, and the stator is configured to follow and rotate at a half rotation speed of the rotor by the rotational force of the rotor. An eccentric screw pump,
The single-shaft eccentric screw pump, wherein the stator has an elastomer portion in which the female screw-shaped inner surface is formed with a constant thickness.   The stator includes a stator inner cylinder, and two stator outer cylinders having a stepped shape formed so as to sandwich the stator inner cylinder from both axial sides thereof. The uniaxial eccentric screw pump according to claim 1, further comprising an elastomer part and a support part integrally formed so as to cover an outer peripheral surface of the elastomer part.   The support portion has flanges projecting in an annular shape outward in the radial direction at both ends thereof, and the elastomer portion is opposed to the stepped shape of the two stator outer cylinders at both ends in the axial direction of the flange. The uniaxial eccentric screw pump according to claim 2, wherein the uniaxial eccentric screw pump is extended to a surface.   The two stator outer cylinders have threaded portions that are screwed to each other at mutually opposing ends, and the stator inner cylinders cooperate with the stepped shape by closing the threaded portions in the axial direction. The single-shaft eccentric screw pump according to claim 2 or 3, characterized in that is sandwiched from both sides in the axial direction.

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