JP2013053601A - Uniaxial eccentric screw pump and fluid motor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a small uniaxial eccentric screw pump and a fluid motor having high accuracy, and rotatable at high speed.SOLUTION: A female screw type stator 20 has an inner peripheral surface defined by a peritrochoid curve, and a male screw type rotor 30 forms three curves of swelling the respective sides of a virtual equilateral triangle inscribed in an inner peripheral surface of the female screw type stator 20 to the inner peripheral surface side as an external shape. In a cross section orthogonal to the axial direction X for extending the female screw type stator 20 and the male screw type rotor 30, while inscribing the three apexes of the male screw type rotor 30 in the inner peripheral surface of the female screw type stator 20, the male screw type rotor 30 eccentrically freely rotates to the female screw type stator 20. Thus, the male screw type rotor 30 has a substantially triangular cross section of swelling the respective sides of an equilateral triangle to the inner peripheral surface side, and rigidity of the male screw type rotor 30 is enhanced.

Description

  The present invention relates to a uniaxial eccentric screw pump that sends out various fluids such as gas, liquid, and powder, and a fluid motor that is operated by a pressurized fluid (hereinafter referred to as “pressurized fluid”).

  For example, as described in Patent Document 1, a uniaxial eccentric screw pump includes a male screw type rotor that extends in a fluid delivery direction and is inserted into a female screw type stator that extends in the same direction. The fluid is sent out by rotating eccentrically relative to the mold stator, and has been widely used conventionally. The female screw type stator is made of an elastic member such as fluororubber, and has an inner peripheral surface that is oval in any cross section perpendicular to the delivery direction. On the other hand, the male screw type rotor is made of a metal material such as stainless steel, and each cross section orthogonal to the delivery direction has a circular shape. The male screw type rotor rotates with a predetermined eccentric amount relative to the cavity of the female screw type stator and functions as a pump.

US Pat. No. 5,120,204

  Since the rotor of the uniaxial eccentric screw pump that has been used conventionally has a snake-like shape, the rigidity of the parts is low, there are limits to high accuracy and miniaturization, and high-speed rotation is difficult.

  Moreover, although the uniaxial eccentric screw pump has a function of converting rotational energy into pressure energy, a fluid motor can be configured with the same basic structure as the uniaxial eccentric screw pump. That is, by allowing the pressurized fluid to flow into the female screw type stator, the male screw type rotor can be rotated in the female screw type stator, and pressure energy can be converted into rotational energy. However, since it has the same basic structure as the conventional single-shaft eccentric screw pump, the same problem, that is, because the rigidity of the male screw type rotor is low, it has been difficult to increase the accuracy, speed and size of the fluid motor. .

  The present invention has been made in view of the above problems, and an object thereof is to provide a small uniaxial eccentric screw pump and a fluid motor that are highly accurate and capable of high-speed rotation.

  In order to achieve the above object, a uniaxial eccentric screw pump according to the present invention includes a female screw type stator having an inner peripheral surface defined by a peritrochoidal curve, and a virtual equilateral triangle inscribed in the inner peripheral surface of the female screw type stator. A male threaded rotor having three curved lines with each side inflated to the inner peripheral surface side. Both the female threaded stator and the male threaded rotor extend in the fluid delivery direction, and In each cross section orthogonal to each other, the male screw type rotor rotates eccentrically relative to the female screw type stator while the three apexes of the male screw type rotor are inscribed in the inner peripheral surface of the female screw type stator, and sends out the fluid. It is characterized by.

  The invention configured as described above is the same as the uniaxial eccentric screw pump described in Patent Document 1 in that the male screw type rotor rotates eccentrically relative to the female screw type stator and sends out the fluid. The female screw type stator and the male screw type rotor have unique shapes that are not present in the past. That is, the female threaded stator has an inner peripheral surface defined by a peritrochoid curve, and the male threaded rotor expands each side of the virtual equilateral triangle inscribed in the inner peripheral surface of the female threaded stator toward the inner peripheral surface side. Three curves are the outer shape. And in the cross section orthogonal to the delivery direction in which the female screw type stator and the male screw type rotor are extended, the male screw type rotor is in contact with the three apexes of the male screw type rotor inscribed in the inner peripheral surface of the female screw type stator. It is eccentric and rotatable with respect to the female screw type stator. Thus, the male screw type rotor has a substantially triangular cross section in which each side of the equilateral triangle is inflated to the inner peripheral surface side, and the rigidity of the male screw type rotor is enhanced compared to the conventional example having a circular cross section, The single-shaft eccentric screw pump can be made more accurate, faster, and smaller.

  In the female screw type stator configured as described above, the internal space surrounded by the inner peripheral surface of the female screw type stator has a bowl shape in each cross section orthogonal to the delivery direction. Therefore, the central part of each curve that defines the external shape of the male screw type rotor is curved to the side opposite to the inner peripheral surface side and interferes with the inner peripheral surface of the female screw type stator in the vicinity of the short axis of the saddle shape. It is desirable to prevent.

  For reasons described later, it is desirable that the ratio of the female screw pitch of the female screw type stator and the male screw pitch of the male screw type rotor be 2: 3. Further, the length of the female screw type stator in the feed direction is at least twice as long as the female screw pitch of the female screw type stator, and the length of the male screw type rotor in the send direction is at least (4 of the male screw pitch of the male screw type rotor. / 3) It is desirable to make it more than double. Thereby, it becomes a closed cavity type, a constant volume type characteristic without leakage is obtained, and the pump (or compressor or dispenser) performance can be improved.

  Moreover, the male screw rotor may be reduced in weight by making the male screw rotor into a hollow rotor, thereby further increasing the rotation speed.

  In addition, a balance weight may be added to the male screw type rotor, whereby vibration during high speed rotation of the male screw type rotor can be reduced, and the uniaxial eccentric screw pump can be stably operated.

  In order to achieve the above object, a fluid motor according to the present invention includes a female screw type stator having an inner peripheral surface defined by a peritrochoid curve, and a virtual equilateral triangle inscribed in the inner peripheral surface of the female screw type stator. A male screw type rotor having three curved lines with each side inflated to the inner peripheral surface side, a rotary shaft provided rotatably around a predetermined rotation axis, a male screw type rotor and the rotary shaft are connected. And a power transmission mechanism for transmitting the rotational force of the male screw type rotor to the rotary shaft, and both the female screw type stator and the male screw type rotor extend in the flow direction of the pressurized fluid and are orthogonal to the flow direction. In each cross section, the male screw rotor is eccentrically rotated in the female screw stator by the pressurized fluid flowing into the female screw stator while the three apexes of the male screw rotor are inscribed in the inner peripheral surface of the female screw stator. And the power transmission mechanism is characterized in that transmits power to the rotary shaft of the eccentric rotation of the male screw rotor from the male screw rotor while converting the rotation of the rotary shaft.

  In the fluid motor configured as described above, like the uniaxial eccentric screw pump, the male screw type rotor has a substantially triangular cross section in which each side of the equilateral triangle is expanded toward the inner peripheral surface side. The rigidity is higher than that of the conventional example having a circular cross section, and the fluid motor can be made highly accurate, highly rotated, and downsized.

  In addition, you may provide a rotating shaft so that a rotating shaft may become parallel to a flow direction, and this can convert the pressure energy which a pressurized fluid has into the rotational energy of a rotating shaft efficiently.

  As described above, the external thread type rotor has three curved lines in which each side of the virtual equilateral triangle inscribed in the internal peripheral surface of the internal thread type stator defined by the peritrochoid curve is expanded on the internal peripheral surface side. Therefore, the rigidity of the male screw type rotor can be increased, and a small uniaxial eccentric screw pump and a fluid motor that can be rotated at high speed with high accuracy can be obtained.

It is a figure which shows one Embodiment of the uniaxial eccentric screw pump concerning this invention. It is a perspective view which shows the structure of a female screw type stator and a male screw type rotor. It is an expanded sectional view of a female screw type stator and a male screw type rotor. It is a figure which shows the shape of the stator and rotor in a cross section orthogonal to a sending direction. It is a figure which shows the determination method of the curve which prescribes | regulates the internal peripheral surface of a stator, and the said curve. It is a figure showing each part of a male screw type rotor. It is a schematic diagram which shows the method of determining the curve shown in FIG. It is a figure which shows the curve which prescribes | regulates the external shape of a male screw type | mold rotor. It is a figure which shows operation | movement of the uniaxial eccentric screw pump shown in FIG.

  FIG. 1 is a view showing an embodiment of a uniaxial eccentric screw pump according to the present invention. This uniaxial eccentric screw pump has a casing 12 connected to the rear end side of the casing 11 (right hand side in the figure) and an outlet guide portion 13 attached to the front end side of the casing 11 (left hand side in the figure). A main body 10 is formed. Of these, the casing 11 has a hollow tube structure extending in a direction X for feeding out fluid (hereinafter referred to as “feeding direction”) X, and a female screw type stator 20 is fixedly arranged in the hollow. Further, the male screw type rotor 30 is fitted and inserted into the female screw type stator 20 so as to be eccentrically rotatable, and the male screw type rotor 30 is eccentrically rotated by the drive mechanism 40, thereby allowing the male screw type rotor 30 to be inserted via the inlet portion 121 of the casing 12. Then, the fluid flowing into the pump body 10 is sent out in the delivery direction X and discharged from the outlet guide portion 13. In addition, since the internal thread type | mold stator 20 and the external thread type rotor 30 are the characterizing parts of this invention, those structures and operation | movement are explained in full detail later. Hereinafter, the female screw type stator 20 and the male screw type rotor 30 are simply referred to as “stator 20” and “rotor 30”, respectively.

  A drive mechanism 40 is provided inside the casing 12. In this drive mechanism 40, a drive shaft 41 connected to a motor (not shown) extends in the X direction, and is rotatably supported by a ball bearing 42 with respect to the casing 12. A tip of the drive shaft 41 is connected to a coupling rod 44 through a flexible joint 43. Further, the front end portion of the coupling rod 44 is connected to the rear end portion of the rotor 30 via the flexible joint 45. Therefore, when the drive shaft 41 is rotationally driven by the operation of the motor, the rotational driving force is transmitted to the rotor 30 via the flexible joint 43, the coupling rod 44, and the flexible joint 45, and the rotor 30 rotates. In this embodiment, a sealing member 46 is provided between the flexible joint 43 and the ball bearing 42 so as to surround the drive shaft 41 in the axial radial direction to form a liquid-tight region, and flows into the pump body 10. The incoming fluid is prevented from leaking to the ball bearing 42 side.

  Next, the configuration and operation of the stator 20 and the rotor 30 will be described with reference to FIGS. 2 to 9. FIG. 2 is a perspective view showing configurations of the female screw type stator and the male screw type rotor, and FIG. 3 is an enlarged cross-sectional view of the female screw type stator and the male screw type rotor. FIG. 4 is a diagram showing the shapes of the stator and the rotor in a cross section orthogonal to the delivery direction. In the present embodiment, the stator 20 has an inner peripheral surface 21 defined by a peritrochoidal curve, and a space 22 surrounded by the inner peripheral surface 21 in each cross section orthogonal to the delivery direction X is shown in FIG. It has a saddle shape.

  FIG. 5 is a diagram showing a curve defining the inner peripheral surface of the stator and a method for determining the curve. The curve used in this embodiment is a peritrochoid curve as described above, and is determined as shown in FIG. That is, a basic circle O1 having a radius “1”, a circle O2 circumscribed by the inner surface thereof (radius r = 1.5), and an epitrochoid generation radius R (R = 3.25) provided integrally with the circle O2. ). Then, when the position of the base circle O1 is fixed and the circle O2 is rolled without slipping around the base circle O1, the curve drawn by the tip of the epitrochoid generation radius R defines a curve that defines the inner peripheral surface 21 of the stator 20 (hereinafter, “ It is referred to as “stator inner surface curve” 23. That is, when the contact point P between the basic circle O1 and the circle 2 is moved from θ = 0 ° to 270 °, the stator inner surface curve 23 becomes a curve indicated by a black circle in FIG. By copying it symmetrically left and right and up and down, it becomes the stator inner surface curve 23 employed in this embodiment as shown in FIG.

  Further, the bowl-shaped inner peripheral surface 21 defined by the stator inner surface curve 23 is twisted in the axial direction, that is, the delivery direction X. That is, as shown in FIG. 3, it is inclined according to the distance in the feed direction (+ X) from the rear end portion of the stator 20, and has a stator pitch P20. In this embodiment, the length of the stator 20 in the axial direction (feeding direction X) is three times the stator pitch P20. In the figure, white circles are added for easy understanding of the inclination of the long axis of the inner peripheral surface 21 in each cross section, and the inclinations of the long axis are −0 °, −90 °, −180 ° and −270 °. The cross-sectional shape of the inner peripheral surface 21 in the case of is shown.

  The rotor 30 is inserted into the internal space 22 surrounded by the inner peripheral surface 21 of the stator 20 configured as described above. The outer shape of the rotor 30 can be defined by three curves. FIG. 6 is a diagram showing a curve defining the outer shape of the male screw type rotor, and FIG. 7 is a schematic diagram showing a method for determining the curve shown in FIG. As shown in FIGS. 3, 4, and 6, the outer shape of the rotor 30 is three in which each side of a virtual equilateral triangle inscribed in the inner peripheral surface 21 in the inner space 22 of the stator 20 is expanded toward the inner peripheral surface 21. The curved line 31 has an outer shape, and at first glance, has a shape similar to the “Ruleaux triangle”, but in order to prevent interference with the inner peripheral surface 21 of the stator 20 in the vicinity of the short axis of the saddle shape, The center portion of each curve 31 is curved to the side opposite to the inner peripheral surface 21 side (that is, the rotation center side), and the shape of the rotor 30 in the cross section orthogonal to the delivery direction X is substantially heart-shaped. . More specifically, the curve 31 is determined as shown in FIGS.

In the following description, the cross section is the YZ plane from the coordinate system of the entire pump, but for convenience of explanation of the mathematical formula, this will be described as the XY plane. The center (x2, y2) of this section of the rotor 30 is a function of θ.

Can be shown. Further, the coordinates (x5 ′, y5 ′) of the intersection between the inner peripheral surface 21 of the stator 20 and the short axis are:

It is. Then, when the coordinates (x5 ′, y5 ′) are obtained with reference to the rotor coordinates rotating as a function of θ around the coordinates (x2, y2), the following coordinates (x5, y5) are obtained.

This is a function that expresses the outer shape of the rotor 30 so that the point (x5 ′, y5 ′) on the stator inner surface curve 23 is always in contact with the rotor 30 regardless of the rotation angle. Similarly to the above, since it is necessary to satisfy the contact with the rotor 30 at any point in the vicinity of the coordinates (x5 ′, y5 ′), instead of (x5 ′, y5 ′) in the above equation, Incorporating an epitrochoidal curve function with the angle ω as a variable,

Get it and organize it

Is obtained. In Equation 5, a curve for each ω (0 ≦ ω ≦ 4π / 5) is obtained in the range of θ (0 ≦ θ ≦ π), and these graphs are shown in FIG. When the function of the envelope of the minimum coordinate value x5 with respect to the value of the coordinate value y5 (broken line in the figure) is obtained, this basically becomes a part of a curve showing the outer shape of the rotor 30 of the present embodiment. More specifically, the curve indicated by the broken line in FIG. 8 is one curve 31a1 constituting the first curve 31a of the three curves 31, and the first curve 31a1 is inverted by being inverted with respect to the symmetry axis 33a. One curve 31b1 constituting the two curves 31b is obtained. Here, the “symmetric axis 33a” means an axis passing through the apex 32a of the rotor 30 and the rotor center coordinates (x2, y2) where the first curve 31a and the second curve 31b are connected, and the first curve 31a and the second curve 31b are line-symmetric with respect to the symmetry axis 33a. The curve 31a1 and the second curve 31b rotated by 120 ° around the rotor center coordinate (x2, y2) constitute one curve constituting the other curve 31b2 and the third curve 31c of the second curve 31b. 31c1 and the one rotated by 240 ° become the other curve 31c2 of the third curve 31c and the other curve 31a2 constituting the first curve 31c. Thus, the three curves 31 (31a to 31c) indicating the outer shape of the rotor 30 are curves obtained by combining two curves (curves indicated by broken lines in FIG. 8) determined as described above.

  The rotor 30 having such an outer shape is also twisted in the axial direction, that is, the feeding direction X, similarly to the stator 20, and has a distance in the feeding direction (+ X) from the rear end portion of the rotor 30 as shown in FIG. Accordingly, the positions of the vertices 32a to 32c are displaced in the rotational direction at the rotor pitch P30. In this embodiment, the length of the roller 30 in the axial direction (feeding direction X) is twice the rotor pitch P. In the figure, in order to make it easy to understand the positions of the vertices 32a to 32c in each cross section, the vertex 32a is marked with a black circle, and the vertex 32a is 0 °, −60 °, −120 °, −180 °, − The cross-sectional shape of the rotor at 240 ° and −300 ° is shown.

  When a rotational driving force is applied to the rotor 30 configured as described above by the drive mechanism 40, the three vertices 32 (32 a to 32 c) of the rotor 30 are connected to the stator 20 in each cross section orthogonal to the delivery direction X. The rotor 30 is eccentrically rotated with respect to the stator 20 while being inscribed in the inner peripheral surface 21 to send out fluid. Here, the operation of the pump in each cross section will be described with reference to FIG.

  FIG. 9 is a diagram showing the operation of the uniaxial eccentric screw pump shown in FIG. When the rotor 30 is eccentrically rotated with respect to the stator 20 in the direction of the arrow in FIG. 6A in response to the rotational driving force applied from the drive mechanism 40, the rotor 30 is upstream of the apex 32 a in the rotational direction. A gap CV is generated as shown in FIG. As the rotor 30 rotates eccentrically, the gap CV increases as shown in FIGS. 3C to 3E. At this time, the fluid flowing into the pump main body 10 via the inlet portion 121 becomes the gap CV. Sucked into. When the rotor 30 is further rotated, the gap CV is gradually reduced as shown in FIGS. 5F to 5H, and is finally completely closed (FIG. 1I). Such an operation sequentially occurs at the other apexes 32b and 32c of the rotor 30.

  On the other hand, since the stator 20 and the rotor 30 are twisted in the axial direction, that is, the delivery direction X, as shown in FIGS. 2 and 3, the above operation is out of phase in each section in the delivery direction (+ X). Therefore, the cavity of the gap CV moves in the delivery direction (+ X) according to the eccentric rotation of the rotor 30, and the fluid is sent out in the (+ X) direction.

  As described above, in the present embodiment, since the rotor 30 has a substantially triangular cross section in which each side of the equilateral triangle is expanded toward the inner peripheral surface, the rigidity of the rotor 30 can be increased, and the uniaxial eccentric screw pump High precision, high rotation, and miniaturization are possible.

  The ratio of the female screw pitch P20 of the stator 20 to the male screw pitch P30 of the rotor 30 is 2: 3. In order to make the three apexes of the rotor 30 in contact with the inner surface of the stator even in the cross section of the uniaxial eccentric screw pump, the rotor 30 can be arranged in any cross section orthogonal to the axial direction (feeding direction X). The center of the screw shaft (the amount of eccentricity E) needs to be at the same position. Therefore, in the uniaxial eccentric screw pump according to the present embodiment, the eccentric circle rotates three times when the rotor 30 makes one rotation (this means that the rotor 30 rotates once for a certain axial cross section). It can be seen from the fact that the eccentric circle of 30 rotates 3 times), the rotor 30 needs to rotate 1/3 of the 1/2 rotation of the stator 20. That is, the spiral pitch ratio is stator pitch P20: rotor pitch P30 = 2: 3.

  In this embodiment, the axial length of the stator 20 is three times the stator pitch P20, and the axial length of the rollers 30 is twice the rotor pitch P, and is configured as described above. Furthermore, the establishment requirement L for allowing the uniaxial eccentric screw pump to function as a closed cavity pump is satisfied. Therefore, the pump according to the present embodiment has a constant volume characteristic without leakage, and can improve the performance of the pump (or compressor, dispenser). The “satisfying requirement L” means a length of 2/3 cycle of the pump cycle (two rotations of the stator 20 and 4/3 rotations of the rotor 30). In other words, if it is shorter than this requirement, one of the cavities is short-circuited in the axial direction (feeding direction X), so that a sufficient pumping operation cannot be obtained as a constant displacement pump. For example, a cavity generated by the rotation of the rotor 30 by −30 ° disappears when the rotor 30 rotates by −270 °, so that the phase of the rotor 30 with respect to the stator 20 is 240 ° (= −30 ° − (− 270).゜)) Need to rotate.

  The present invention is not limited to the above-described embodiment, and various modifications other than those described above can be made without departing from the spirit of the present invention. For example, a balance weight may be added to the rotor 30. In this case, the addition of the balance weight can reduce the vibration when the rotor 30 rotates at high speed, and the uniaxial eccentric screw pump can be operated stably.

  The rotor 30 may be a solid structure or a hollow structure, but it is desirable to use the hollow structure rotor 30 from the viewpoint of weight reduction. Further, when the hollow structure rotor 30 is employed, a balance weight may be disposed in the hollow portion.

  Moreover, in the said embodiment, although the rotor 30 is eccentrically rotated using a flexible joint, the structure of the drive mechanism 40 is not limited to the said embodiment, For example, the eccentric drive mechanism used frequently conventionally, for example, An eccentric drive mechanism using a planetary gear may be used. In the above embodiment, the rotor 30 is driven to rotate while fixing the stator 20. However, the driving method is not limited to this, and the rotor 30 is relatively eccentric with respect to the stator 20. What is necessary is just to drive.

  Furthermore, in the above-described embodiment, the rotor 30 is driven eccentrically relative to the stator 20 to convert rotational energy into pressure energy and send out various fluids such as gas, liquid, and powder (compressor and dispenser). The technical idea of the present invention can also be applied to a fluid motor. That is, as shown by the arrows in parentheses in FIG. 1, when pressurized fluid is supplied via the outlet guide portion 13, the rotor 30 rotates eccentrically in the stator 20 due to the pressure energy of the pressurized fluid. A power transmission mechanism having the same configuration as that of the drive mechanism 40 performs power transmission from the rotor 30 to the drive shaft 41 while converting eccentric rotation of the rotor 30 into rotation of the drive shaft (rotary shaft) 41. In this way, the drive shaft 41 is rotationally driven. Therefore, for example, by attaching a rotary machining tool such as a drill to the drive shaft 41, it is possible to function as a fluid motor (pneumatic motor, hydraulic motor, hydraulic motor, etc.) for rotating the tool.

  According to the fluid motor configured as described above, similarly to the uniaxial eccentric screw pump, the rotor 30 has a substantially triangular cross section in which each side of an equilateral triangle is inflated toward the inner peripheral surface side, thereby increasing the rigidity of the rotor. Therefore, compared with a fluid motor having the same structure as the pump described in Patent Document 1, it is possible to increase the accuracy, increase the speed, and reduce the size of the fluid motor.

  Further, since the drive shaft 41 is provided so that the rotational axis of the drive shaft 41 is parallel to the flow direction X of the pressurized fluid, the pressure energy of the pressurized fluid is efficiently converted into the rotational energy of the drive shaft 41. can do.

  Further, instead of using a power transmission mechanism having the same configuration as that of the drive mechanism 40, a power transmission mechanism using a planetary gear, for example, may be used as in the case of the uniaxial eccentric screw pump.

  The present invention can be applied to uniaxial eccentric screw pumps that send out various fluids such as gas, liquid, and powder, and fluid motors that operate by pressurized fluid.

DESCRIPTION OF SYMBOLS 20 ... Female thread type stator 21 ... Inner peripheral surface 23 ... Stator inner surface curve 30 ... Male screw type rotor 31, 31a-31c ... Curve 32, 32a-32c ... Apex P20 ... Stator pitch P30 ... Rotor pitch X ... Delivery direction

Claims (8)

An internal thread type stator having an inner peripheral surface defined by a peritrochoid curve;
A male screw type rotor having an outer shape of three curves obtained by inflating each side of a virtual equilateral triangle inscribed in the inner peripheral surface of the female screw type stator toward the inner peripheral surface side;
The female screw type stator and the male screw type rotor are both extended in the fluid delivery direction,
In each cross section orthogonal to the delivery direction, the male screw type rotor is relative to the female screw type stator while the three apexes of the male screw type rotor are inscribed in the inner peripheral surface of the female screw type stator. A single-shaft eccentric screw pump characterized in that it is eccentrically rotated and pumps out fluid. The internal space surrounded by the inner peripheral surface of the female screw type stator in each cross section orthogonal to the delivery direction of the female screw type stator has a bowl shape,
The center part of each curve curves to the opposite side to the said inner peripheral surface side, and is non-interfering with the inner peripheral surface of the said internal thread type stator in the vicinity of the short axis of the said saddle shape. Uniaxial eccentric screw pump.   The uniaxial eccentric screw pump according to claim 1 or 2, wherein a ratio of a female screw pitch of the female screw type stator to a male screw pitch of the male screw type rotor is 2: 3.   The length of the female screw type stator in the feeding direction is at least twice as long as the female screw pitch of the female screw type stator, and the length of the male screw type rotor in the sending direction is at least a male size of the male screw type rotor. The uniaxial eccentric screw pump according to any one of claims 1 to 3, wherein the uniaxial eccentric screw pump is at least (4/3) times the screw pitch.   The uniaxial eccentric screw pump according to any one of claims 1 to 4, wherein the male screw type rotor is a hollow rotor.   The uniaxial eccentric screw pump according to any one of claims 1 to 5, wherein a balance weight is added to the male screw type rotor. An internal thread type stator having an inner peripheral surface defined by a peritrochoid curve;
A male screw type rotor having an outer shape of three curves obtained by inflating each side of a virtual equilateral triangle inscribed in the inner peripheral surface of the female screw type stator toward the inner peripheral surface side;
A rotating shaft provided rotatably around a predetermined rotation axis;
A power transmission mechanism for connecting the male screw type rotor and the rotary shaft to transmit the rotational force of the male screw type rotor to the rotary shaft;
The female screw type stator and the male screw type rotor are both extended in the flow direction of the pressurized fluid,
In each cross section orthogonal to the flow direction, the male screw type rotor is in contact with the inner peripheral surface of the female screw type stator while the three apexes of the male screw type rotor are in contact with the male screw type stator by the pressurized fluid flowing into the female screw type stator. A screw type rotor rotates eccentrically in the female screw type stator;
The fluid motor is characterized in that the power transmission mechanism transmits power from the male screw type rotor to the rotary shaft while converting eccentric rotation of the male screw type rotor to rotation of the rotary shaft.   The fluid motor according to claim 7, wherein the rotation shaft is provided such that the rotation axis is parallel to the flow direction.