TW201621166A - Uniaxial eccentric screw pump - Google Patents

Abstract

The purpose of the present invention is to provide a uniaxial eccentric screw pump which is compact in the length direction and is less likely to suffer from such problems as stick slippage and damage to a shaft joint. The uniaxial eccentric screw pump (10) has: a driving force transmission part (72) which is rotated by driving force of a driving machine (80); a rotor (60) which is constituted by a male screw shaft body; a stator (50) in which the rotor (60) can be inserted, said stator (50) having an inner circumferential surface (52) that is formed into a female screw ; and a shaft joint (76) which joins the driving force transmission part (72) with the rotor (60) in an eccentrically rotatable manner such that the rotor (60) revolves along the inner circumferential surface (52) of the stator (50) while rotating inside the stator (50). The shaft joint (76) is constituted by a flexible shaft joint and has elasticity in the axial direction.

Description

Single-axis eccentric screw pump

The present invention relates to a uniaxial eccentric screw pump.

Conventionally, a uniaxial eccentric screw pump as disclosed in Patent Document 1 below has been provided. In the uniaxial eccentric screw pump of the following Patent Document 1, the drive-side shaft body that is rotated by the turning power generated by the drive unit and the shaft-side shaft body that constitutes the rotor are used as the shaft joint for connection. Sex rod.

[Practical Technical Literature] [Patent Document]

[Patent Document 1] Japanese Patent Laid-Open Publication No. 2012-154215

Here, the flexible rod used in the above-described conventional technique is required to form a long shape in order to allow the operation of the eccentrically rotating rotor. Therefore, in the prior art, the full length of the uniaxial eccentric screw pump has Not a long-term tendency.

On the other hand, when the uniaxial eccentric screw pump uses a shaft joint such as a pin joint, it is possible to suppress the case where the full length is long, such as when a flexible rod is used. On the other hand, when a pin joint is used, there is a fear that contamination (contamination) of foreign matter generated by abrasion or the like occurs.

Moreover, the flow body of the pressure-feeding object has a low viscosity, and when it is sent by a low-speed pressure, a stick-slip phenomenon occurs, and there is a concern that the flow rate is unstable and abnormal noise occurs. Further, if the discharge pressure is too large, an excessive load acts on the shaft joint, and the possibility of breakage of the shaft joint cannot be completely denied.

Here, in order to solve the above problems, an object of the present invention is to provide a uniaxial eccentric screw pump which is compact in the longitudinal direction and which is less likely to cause a flow material to be mixed into a shaft joint.

The uniaxial eccentric screw pump according to the present invention, which is provided with the above-mentioned problem, has a drive-side rotating portion that is rotated by the power of the drive machine, a rotor composed of a male-thread type shaft body, and a plug-in The stator and the rotor are formed on the inner circumferential surface of the rotor, and the rotor is eccentrically rotatable around the inner circumferential surface of the stator so as to be rotatable inside the stator. The shaft joint is formed of a flexible shaft joint and has an elastic force in the axial direction.

In the uniaxial eccentric screw pump of the present invention, the shaft joint for driving the rotation portion and the rotor is a flexible shaft joint. Flexible shaft connection The head is a shaft joint that can allow deflection in a direction crossing the axial direction and suppress twisting in a direction around the axis. Therefore, in the uniaxial eccentric screw pump of the present invention, stick-slip does not occur, and the rotor can be smoothly rotated on the inner side of the stator. Thereby, the operational stability of the uniaxial eccentric screw pump can be improved.

Also, in the present invention, since the flexible shaft joint is employed, the total length of the uniaxial eccentric screw pump is not as long as the case of using a flexible rod. Further, by using the flexible shaft joint, it is possible to minimize the problem that the foreign matter is mixed into the fluid with the wear of the shaft joint.

Further, in the present invention, the shaft joint has elasticity in the axial direction (thrust direction). Therefore, in the uniaxial eccentric screw pump of the present invention, the shaft joint contracts in the axial direction when the discharge pressure is excessively large. Along with this, the relative position of the rotor of the stator is in a state of being displaced in the axial direction, and it is possible to prevent the excessive discharge pressure from acting on the shaft joint. Therefore, in the uniaxial eccentric screw pump of the present invention, when the discharge pressure is appropriately discharged within the appropriate range, and the discharge pressure is excessively large, the shaft joint can be prevented from being damaged due to an excessive load.

In addition, the uniaxial eccentric screw pump of the present invention provided to solve the same problem includes a driving-side rotating portion that is rotated by the power of the driving machine, and a rotor composed of a male-threaded shaft body, and a stator that is inserted into the rotor and has a female screw-type inner circumferential surface, and the rotor is eccentrically rotatable around the inner circumferential surface of the stator so as to be rotatable around the inner circumferential surface of the stator, and the driving-side rotating portion and the rotor are eccentrically rotatable a coupled shaft joint, the shaft joint having an elastic force in an axial direction of the rotor, The deflection in the direction intersecting the aforementioned axial direction can be tolerated, and the twist in the direction around the aforementioned axis can be suppressed.

In the uniaxial eccentric screw pump of the present invention, a shaft joint that allows bending in a direction crossing the axial direction and suppresses twisting in a direction around the axis is employed. Thereby, the stick slip does not occur, and the rotor can be rotated inside the stator. Thereby, the operational stability of the uniaxial eccentric screw pump can be improved.

Further, by using the shaft joint according to the present invention, it is possible to suppress the length of the uniaxial eccentric screw pump as long as the flexible rod is used. Further, according to the present invention, it is possible to minimize the problem that the foreign matter is mixed into the fluid with the abrasion of the shaft joint.

Further, in the present invention, the shaft joint has elasticity toward the axial direction of the rotor, and if the discharge pressure is excessively large, the shaft joint contracts in the axial direction. Therefore, even if the discharge pressure is too large, the relative position of the rotor of the stator is reduced by the state of being displaced in the axial direction. Thereby, it is possible to avoid damage to the shaft joint by the influence of the discharge pressure.

In the uniaxial eccentric screw pump of the present invention, the elastic modulus of at least a part of the longitudinal direction of the shaft joint is equal to or lower than the elastic modulus of the other portion.

In the uniaxial eccentric screw pump of the present invention, the elastic modulus of at least a part of the longitudinal direction of the shaft joint is equal to or less than the other portions. That is, the shaft joint used in the present invention has at least a portion having an easily deflectable property and a non-twisting property at the other portion. Therefore, with the above configuration, the entire shaft joint can be optimized for deflection and twist. Ie, the shaft The joint is also characterized by being flexible and not easily twisted. Thereby, even when the low-viscosity fluid is used under the cool use conditions of low-pressure pressure, the occurrence of stick slip can be minimized. Further, in the shaft joint used in the present invention, even if the discharge pressure is excessively large, the torque load acting on the shaft joint is not excessively large, and the breakage of the shaft joint can be suppressed.

Further, by providing a different portion of the elastic modulus in the longitudinal direction of the shaft joint, the elasticity of the shaft joint in the thrust direction can be easily and accurately adjusted. Therefore, according to the present invention, an appropriate discharge pressure can be exerted, and the elasticity of the shaft joint in the thrust direction can be optimized.

In the uniaxial eccentric screw pump according to the present invention, the shaft joint includes a drive side connection end connected to the drive side rotation unit, and a rotor side connection end connected to the rotor side, the drive side connection end and the aforementioned The elastic modulus of the rotor-side connecting end may be equal to or less than the intermediate portion between the driving-side connecting end and the rotor-side connecting end.

In the shaft joint used in the present invention, both end portions (drive side connection end and rotor side connection end) tend to be more easily deflected than the intermediate portion. Further, the intermediate portion tends to be less likely to be twisted than the both end portions of the shaft joint. Therefore, the above-described shaft joint can allow the entire deflection and suppress the twist. Since the uniaxial eccentric screw pump of the present invention uses such a shaft joint, the stick slip is less likely to occur, and the rotor can be smoothly rotated.

Further, in the uniaxial eccentric screw pump of the present invention, the shaft joint has a drive side connection end connected to the drive side rotation portion, and a rotor side connection end connected to the rotor side, the drive side connection end and The elastic coefficient of the rotor-side connecting end is the aforementioned driving side connection The intermediate portion of the end and the rotor-side connecting end may be equal to or greater than the intermediate portion.

The shaft joint used in the present invention tends to be more easily deflected at the intermediate portion than at both end portions (the drive side connection end and the rotor side connection end). Further, both end portions of the shaft joint tend to be less likely to be twisted than the intermediate portion. Therefore, the above-described shaft joint has a property of allowing the entire deflection and suppressing the twist. Since the uniaxial eccentric screw pump of the present invention employs such a shaft joint, stick-slip is less likely to occur, and the rotor can be smoothly rotated.

In the above-described uniaxial eccentric screw pump of the present invention, the intermediate portion is formed in a columnar shape or a cylindrical shape, and either or both of the drive-side connecting end and the rotor-side connecting end are preferably formed in a coil spring shape.

In the shaft joint used in the present invention, both end portions are more easily deflected than the intermediate portion, and the intermediate portion tends to be less likely to be twisted than the both end portions of the shaft joint, and has a property of allowing the entire deflection and suppressing the twist. Since the uniaxial eccentric screw pump of the present invention uses such a shaft joint, stick-slip is less likely to occur, and it is excellent in the surface of operational stability.

Further, at least one of the drive side connection end and the rotor side connection end of the shaft joint used in the present invention is formed in a coil spring shape. Therefore, if the magnitude of the thrust load generated by the discharge pressure is too large, the shaft joint will be in a contracted state. Thereby, the rotor is in a state of moving toward the drive side. Further, the line contact of the outer peripheral surface of the rotor on the inner circumferential surface of the stator is released. Thereby, it is possible to avoid excessive pressure acting on the shaft joint or the like, and to minimize the risk of damage such as the shaft joint.

In the uniaxial eccentric screw pump according to the present invention, the diameter of the shaft joint is one of the drive side rotation portion and the rotor or It is better for both sides.

According to this configuration, since the torque rigidity of the shaft joint is further improved, the torsion can be suppressed, so that the occurrence of stick slip can be minimized.

In the uniaxial eccentric screw pump according to the present invention, the outer peripheral surface of the rotor is formed by fluid contact with the inner circumferential surface of the stator, and the load acting from the rotor side toward the driver side exceeds a predetermined value. Under the condition of the size, the movement toward the driving machine side of the rotor is allowed, and the line contact between the rotor and the stator is preferably released.

According to this configuration, even if the excessive thrust load is applied by the discharge pressure, the excessive pressure does not act on the shaft joint or the like. Thereby, damage of the shaft joint or the like can be minimized.

According to the present invention, it is possible to provide a uniaxial eccentric screw pump which is compact in the longitudinal direction and which is less prone to sticking and slippage and breakage of the shaft joint.

10‧‧‧Single-axis eccentric screw pump

30‧‧‧Single-axis eccentric screw pump mechanism

40‧‧‧ Shell

42‧‧‧First opening

44‧‧‧second opening

46‧‧‧Intermediate

50‧‧‧ Stator

52‧‧‧ inner circumference

54‧‧‧through holes

56‧‧‧Fluid handling road

60‧‧‧Rotor

60a, 73a, 78a‧‧‧ threaded holes

60b, 73b, 78b‧‧‧ threaded shaft

62‧‧‧ outer perimeter

70‧‧‧Power transmission agency

72‧‧‧Power Transmission Department

73‧‧‧Rotary shaft (drive side rotation)

74‧‧‧Eccentric rotation

76,176,276‧‧‧ shaft joint

76a, 176a, 276a, 376a‧‧‧ drive side connection

76b, 176b, 276b, 376b‧‧‧ rotor side connection

76c, 176c, 276c‧‧‧ middle part

80‧‧‧ drive machine

90‧‧‧Links

92,94‧‧ Thread Department

376‧‧‧ Stress Diffusion Department

Fig. 1 is a cross-sectional view showing a uniaxial eccentric screw pump according to an embodiment of the present invention.

[Fig. 2] (a) is an exploded view showing a connection structure of a shaft joint 76 in the uniaxial eccentric screw pump of Fig. 1, and (b) is an exploded view of a modification of (a).

[Fig. 3] A front view showing a modification of the shaft joint.

[Fig. 4] A front view showing another modification of the shaft joint.

[Fig. 5] A front view showing still another modification of the shaft joint.

Hereinafter, the uniaxial eccentric screw pump 10 according to an embodiment of the present invention will be described in detail with reference to the drawings. As shown in Fig. 1, the uniaxial eccentric screw pump 10 is a rotary displacement type pump in which a uniaxial eccentric screw pump mechanism 30 is mainly used. As shown in FIG. 1, the uniaxial eccentric screw pump 10 has a configuration in which the stator 50, the rotor 60, the power transmission mechanism 70, and the like are housed inside the casing 40. The outer casing 40 is a metal tubular member, and the first opening portion 42 is provided on one end side in the longitudinal direction. Further, a second opening portion 44 is provided in an outer peripheral portion of the outer casing 40. The second opening portion 44 communicates with the internal space of the outer casing 40 at the intermediate portion 46 located at the intermediate portion in the longitudinal direction of the outer casing 40.

The first opening portion 42 and the second opening portion 44 are portions that function as a suction port and a discharge port of the pump mechanism 30, respectively. In the uniaxial eccentric screw pump 10, by rotating the rotor 60 in the forward direction, the first opening portion 42 can be used as a discharge port, and the second opening portion 44 can function as a suction port. And, by rotating the rotor 60 in the opposite direction, the first The opening 42 serves as a suction port, and the second opening 44 functions as a discharge port.

The stator 50 is a member having a substantially cylindrical outer shape formed of an elastic body such as rubber or a material mainly composed of a resin or the like. The inner circumferential surface 52 of the stator 50 is a member having n+1 (n=1 in the present embodiment) female thread shape. Further, the through hole 54 of the stator 50 is at any position in the longitudinal direction of the stator 50, and the cross-sectional shape (opening shape) in cross section is formed into a substantially elliptical shape.

The rotor 60 is a metal shaft body made of a male thread (n=1 in the present embodiment). The rotor 60 is at any position in the longitudinal direction, and the cross-sectional shape in cross section is formed into a substantially perfect circle. The rotor 60 is inserted through the through hole 54 formed in the stator 50 described above, and is eccentrically rotatable inside the through hole 54.

When the rotor 60 is inserted into the stator 50, the outer circumferential surface 62 of the rotor 60 and the inner circumferential surface 52 of the stator 50 are in close contact with each other, and between the inner circumferential surface 52 of the stator 50 and the outer circumferential surface of the rotor 60. A fluid carrying path 56 (groove) is formed. The fluid conveyance path 56 extends in a spiral shape in the longitudinal direction of the stator 50 and the rotor 60.

When the rotor 60 rotates in the through hole 54 of the stator 50, the fluid transfer path 56 advances in the longitudinal direction of the stator 50 while rotating in the stator 50. Therefore, when the rotor 60 is rotated, the fluid is sucked into the fluid transfer path 56 from the one end side of the stator 50, and the fluid is confined in the fluid transfer path 56, and is transferred toward the other end side of the stator 50, so that it can be moved toward the other end side of the stator 50. The other end side of the stator 50 is discharged. Pump of this embodiment The mechanism 30 is configured to rotate the viscous hydraulic pressure sucked from the second opening portion 44 by rotating the rotor 60 in the forward direction, and is discharged from the first opening portion 42.

The power transmission mechanism 70 transmits power to the rotor 60 from the drive unit 80. The power transmission mechanism 70 includes a power transmission unit 72 and an eccentric rotation unit 74. The power transmission unit 72 is provided on one end side of the outer casing 40 in the longitudinal direction. The power transmission unit 72 is a rotation shaft 73 (drive side rotation unit) that rotates while receiving power from the drive unit 80.

The eccentric rotating portion 74 is provided in the intermediate portion 46 of the outer casing 40. The eccentric rotating portion 74 is a portion that can connect the power transmitting portion 72 and the rotor 60 to each other. In the eccentric rotating portion 74, a shaft joint 76 is employed as will be described in detail later. Thereby, the eccentric rotating portion 74 transmits the turning power generated by the operation of the driving machine 80 to the rotor 60, and the rotor 60 can be eccentrically rotated.

The shaft joint 76 is a joint for rotatably connecting the power transmission portion 72 and the rotor 60 so that the rotor 60 rotates inside the stator 50 and revolves along the inner circumferential surface 52 of the stator 50. The shaft joint 76 is composed of a flexible shaft joint. The shaft joint 76 is a joint having a property of allowing deflection in a direction crossing the axial direction and suppressing torsion in a direction around the axis.

The shaft joint 76 is a joint having a shaft shape or a cylindrical outer shape in which the elastic modulus of at least a part of the longitudinal direction of the shaft joint is equal to or less than the elastic modulus of the other portion. Specifically, the shaft joint 76 is formed in the middle and processed by machining a metal shaft body. As shown in Fig. 1 and Fig. 2, the shaft joint 76 is a drive side having a coil spring shape at both end portions in the axial direction. The connection end 76a and the rotor side connection end 76b have a medium intermediate portion 76c therebetween. Thereby, the spring constant of the shaft joint 76 in the intermediate portion 76c is equal to or less than the spring constant of the drive side connecting end 76a and the rotor side connecting end 76b provided at both ends. Further, the diameter of the shaft joint 76 is equal to or larger than the diameter of both the power transmitting portion 72 and the rotor 60.

As shown in FIG. 2, the shaft joint 76 is connected to the rotor 60 and the power transmission portion 72 by using the joint pin 90. Specifically, the coupling pin 90 is a pin having screw portions 92 and 94 in which the reverse threads are formed at both end portions. In the drive side connection end 76a and the rotor side connection end 76b of the shaft joint 76, screw holes 78a and 78b having reversely threaded shapes are provided. Further, the base end portion of the rotor 60 and the tip end portion of the rotation shaft 73 of the power transmission portion 72 are also provided with screw holes 60a and 73a which are reversely threaded. The rotor 60 and the shaft joint 76 are coupled by screwing the screw portions 92 and 94 of the coupling pin 90 to the screw holes 60a and 78a. Further, the rotation shaft 73 and the shaft joint 76 of the power transmission portion 72 are coupled by screwing the screw portions 92 and 94 of the coupling pin 90 to the screw holes 73a and 78b.

As described above, the shaft joint 76 that connects the rotating shaft 73 and the rotor 60 is a flexible shaft joint. In other words, the shaft joint 76 is configured to allow deflection in a direction intersecting the axial direction and suppress twisting in a direction around the axis. Therefore, in the uniaxial eccentric screw pump 10, even when the low-viscosity fluid is used under the cold use conditions of low-speed pressure, the stick-slip does not occur, and the rotor 60 can be smoothly smoothed inside the stator 50. Rotate. Therefore, the uniaxial eccentric screw pump 10 is excellent in the surface of the operational stability.

Further, in the uniaxial eccentric screw pump 10, since the shaft joint 76 is a flexible shaft joint, the interval between the rotary shaft 73 and the rotor 60 is not as long as the case of using a flexible rod. Thereby, the uniaxial eccentric screw pump 10 can be made compact in the longitudinal direction. Further, the flexible shaft joint forming the shaft joint 76 is such that foreign matter generated by abrasion does not occur as compared with the pin joint. Therefore, in the uniaxial eccentric screw pump 10, the problem that the foreign matter is mixed into the fluid with the abrasion of the shaft joint 76 can be minimized.

Further, in the uniaxial eccentric screw pump 10, the shaft joint 76 has elasticity toward the axial direction. Therefore, when the excessive discharge pressure is applied, the shaft joint 76 is contracted in the axial direction so that the relative position of the rotor 60 of the stator 50 is displaced in the axial direction, and the line contact between the rotor 60 and the stator 50 is released. Thereby, an excessive discharge pressure can be avoided from acting on the shaft joint 76. Therefore, the uniaxial eccentric screw pump 10 can prevent the shaft joint 76 from being damaged by an excessive load even when the discharge pressure is appropriately discharged and the discharge pressure is excessively discharged.

As described above, in the uniaxial eccentric screw pump 10, the elastic coefficients of both end portions (the drive side connection end 76a and the rotor side connection end 76b) of the shaft joint 76 are equal to or less than the intermediate portion 76c. That is, both end portions of the shaft joint 76 are formed in a spring shape. Therefore, the shaft joint 76 tends to be more easily deflected than the intermediate portion 76c at the drive side connection end 76a and the rotor side connection end 76b. Further, the intermediate portion 76c tends to be less likely to be twisted than the both end portions of the shaft joint 76. Therefore, the shaft joint 76 is capable of allowing overall deflection and suppressing twisting. The uniaxial eccentric screw pump 10 is connected to the rotating shaft 73 by using the shaft joint 76 having such a characteristic, so even if it is low-viscosity Sexual fluids are used under the conditions of cool use of low-speed pressure, and stick-slip is not easy to produce.

In the uniaxial eccentric screw pump 10 described above, the rotor 60 and the rotating shaft 73 of the power transmission unit 72 are connected to the shaft joint 76 via the coupling pin 90. However, the uniaxial eccentric screw pump may be connected by any other method. Specifically, as shown in FIG. 2(b), screw shafts 60b and 73b are provided at the end of the rotor 60 and the end of the rotary shaft 73, and these are screwed into the screw holes 78a on the side of the shaft joint 76, 78b and the connection is OK.

Further, in the present embodiment, the elastic coefficient of the drive side connecting end 76a and the rotor side connecting end 76b is set to be lower than the intermediate portion 76c, but the elastic modulus of at least a part of the longitudinal direction of the shaft joint 76 is the elastic coefficient of the other portion. The following can be said. That is, instead of the shaft joint 76, the shaft joint 176 shown in Fig. 3 may be used, and the drive side connection end 176a and the rotor side connection end 176b may have a cylindrical shape or a shaft shape, and the intermediate portion 176c may be a spring shape.

The above-described shaft joint 176 has a spring constant of the drive side connecting end 176a and the rotor side connecting end 176b which is equal to or greater than the intermediate portion 176c. The shaft joint 176 tends to be more easily deflected than the both end portions (the drive side connection end 176a and the rotor side connection end 176b). Further, both end portions of the shaft joint 176 tend to be less likely to be twisted than the intermediate portion 176c. Therefore, the shaft joint 176 has characteristics of allowing the entire deflection and suppressing the twist as in the above-described shaft joint 76. Therefore, in the case where the shaft joint 176 is used instead of the shaft joint 76, even when the low-viscosity fluid is used under the cool use conditions of low-pressure pressure, the stick-slip is also used. Not easy to produce.

Further, the above-described shaft joints 76 and 176 are shaft joints that connect the rotation shaft 73 and the rotor 60 so that the elastic coefficients of the drive side connection ends 76a and 176a and the rotor side connection ends 76b and 176b are equal to or smaller than the intermediate portions 76c and 176c. Not limited to these. In other words, if it has elasticity in the axial direction, the elastic coefficient may be substantially the same from the driving side connecting end 276a through the intermediate portion 276c to the rotor side connecting end 276b. Specifically, the shaft joint 276 shown in Fig. 4 may be formed in a spring shape over substantially the entire lengthwise direction. In the case of such a configuration, as long as the shaft joint 276 can allow the deflection in the direction intersecting the axial direction and suppress the twist in the direction around the axis, the same effects as those of the above-described shaft joints 76 and 176 can be obtained. .

Further, when the shaft joints 76, 176, and 276 described above are provided with a spring-like portion, there is a fear that stress generated by torsion and deflection concentrates on the end portion of the portion where the spring is formed. Therefore, in the shaft joints 76, 176, and 276, it is preferable to use a countermeasure against the concentration of stress at the end portion of the portion where the spring is formed. Specifically, when the drive-side connecting end 376a and the rotor-side connecting end 376b form a spring-like portion in a spiral shape, the shaft joint 376 shown in Fig. 5 is provided with a groove at the end portion thereof. The region where the width is larger than the other portions (the stress diffusion portion 376d) can expand the field of the stress caused by the torsion and the deflection, and the effect of avoiding the stress concentration can be expected.

The present embodiment is merely an embodiment of the present invention, and the present invention is of course not limited to the above.

[Industrial Availability]

The present invention is applicable to all single-axis eccentric screw pumps.

10‧‧‧Single-axis eccentric screw pump

30‧‧‧Single-axis eccentric screw pump mechanism

40‧‧‧ Shell

42‧‧‧First opening

44‧‧‧second opening

46‧‧‧Intermediate

50‧‧‧ Stator

52‧‧‧ inner circumference

54‧‧‧through holes

56‧‧‧Fluid handling road

60‧‧‧Rotor

62‧‧‧ outer perimeter

70‧‧‧Power transmission agency

72‧‧‧Power Transmission Department

74‧‧‧Eccentric rotation

76‧‧‧ shaft joint

76a‧‧‧Drive side connector

76b‧‧‧Rotor side connection

76c‧‧‧Intermediate

80‧‧‧ drive machine

90‧‧‧Links

Claims (8)

A uniaxial eccentric screw pump comprising: a driving side rotating portion that is rotated by a power of a driving machine; a rotor composed of a male screw type shaft body; and an inner peripheral surface that can be inserted through the rotor a stator that forms a female screw type, and the rotor is a shaft joint that is eccentrically rotatable around the inner circumferential surface of the stator and that rotatably connects the driving side rotating portion and the rotor, the shaft joint It is composed of a flexible shaft joint and has an elastic force in the axial direction. A uniaxial eccentric screw pump comprising: a driving side rotating portion that is rotated by a power of a driving machine; a rotor composed of a male screw type shaft body; and an inner peripheral surface that can be inserted through the rotor a stator that forms a female screw type, and the rotor is a shaft joint that is eccentrically rotatable around the inner circumferential surface of the stator and that rotatably connects the driving side rotating portion and the rotor, the shaft joint It is an elastic force in the axial direction of the rotor, and it is allowed to bend in a direction intersecting the axial direction, and to suppress the twist in the direction around the axis. The uniaxial eccentric screw pump according to claim 1 or 2, wherein the elastic modulus of at least a part of the longitudinal direction of the shaft joint is equal to or less than the elastic modulus of the other portion. The uniaxial eccentric screw pump according to claim 3, wherein the shaft joint has a drive side connection end connected to the drive side rotation unit and a rotor side connection end connected to the rotor side. The elastic coefficient of the drive side connecting end and the rotor side connecting end is equal to or less than an intermediate portion between the drive side connecting end and the rotor side connecting end. The uniaxial eccentric screw pump according to claim 3, wherein the shaft joint has a drive side connection end connected to the drive side rotation unit and a rotor side connection end connected to the rotor side. The elastic coefficient of the drive side connection end and the rotor side connection end is equal to or greater than an intermediate portion between the drive side connection end and the rotor side connection end. The uniaxial eccentric screw pump according to the fourth aspect of the invention, wherein the intermediate portion between the driving side connecting end and the rotor side connecting end is a columnar shape or a cylindrical shape, and the driving side connecting end and the rotor side are One or both of the connecting ends are formed in a coil spring shape. The uniaxial eccentric screw pump according to the first or second aspect of the invention, wherein the diameter of the shaft joint is equal to or larger than a diameter of one or both of the driving-side rotating portion and the rotor. A uniaxial eccentric screw pump as described in claim 1 or 2, wherein The outer peripheral surface of the rotor is formed by a line contact with the inner peripheral surface of the stator to form a fluid transport path, and the load acting from the rotor side toward the drive side exceeds a predetermined size as a condition, and the rotor is formed toward the rotor. The movement on the side of the drive unit is allowed to be released, and the line contact between the rotor and the stator is released.