SINGLE-AXLE ECCENTRIC SCREW PUMP

Abstract

Single-axis eccentric screw pump with: a rotor (1) with a shaft body with external thread; a stator (2) with a through-hole provided with an internal thread, through which the rotor (1) is inserted; a housing (3) which can be connected to an end side of the stator (2); an end piece (4) that can be connected to the other end of the stator (2); and a position setting element (5) that sets a relative position of the stator (2) relative to the rotor (1) in an axial direction, wherein the position adjusting element (5) is detachably attached both to the part between the stator (2) and the housing (3) and to the part between the stator (2) and the end piece (4).

Description

TECHNICAL FIELD

[0001] The present invention relates to a single-axis or uniaxial eccentric screw pump. STATE OF THE ART

[0002] Conventionally, a single-axis eccentric screw pump is known which comprises a spiral-shaped rotor which has a conical shape from one end to the other end and a stator with a through-bore through which the rotor can be inserted (see, for example, US 9 109 595 A1).

[0003] However, in the conventional single-axis progressive cavity pump, a mechanism for adjusting the relative position or positional relationship between the stator and the rotor in the axial direction has not been sufficiently investigated.

[0004] DE 10 2015 101 352 A1 or DE 10 1016 121 581 A1 each discloses a single-axis eccentric screw pump comprising a rotor with a shaft body having an external thread, a stator with an internally threaded through-bore through which the rotor is inserted, a housing connectable to one end of the stator, an end piece connectable to the other end of the stator, and a position adjustment element that adjusts a relative position of the stator relative to the rotor in an axial direction. Further relevant prior art is US 2018 / 0 003 174 A1. BRIEF EXPLANATION OF THE INVENTION TASK TO BE SOLVED BY THE INVENTION

[0005] It is an object of the present invention to provide a single-axis progressive cavity pump capable of freely adjusting a relative position of a stator with respect to a rotor in an axial direction. FACILITY FOR SOLVING THE TASK

[0006] The present invention provides a device for solving the above-mentioned problem, a single-axis eccentric screw pump having the features listed in the independent claims.

[0007] According to this structure, the relative positional relationship of the stator with respect to the rotor in the axial direction is adjustable by the position adjusting member.

[0008] Preferably, a connecting part is provided which transmits power from a drive source to the rotor, and the position adjusting element is detachably provided at an end part or in the middle of the rotor, the stator, the housing and / or the connecting part.

[0009] Preferably, the position adjusting element is detachably attached to at least a part between the stator and the housing or a part between the stator and the end piece.

[0010] According to this structure, by arranging the position adjustment element between the stator and the housing, the rotor can be moved closer to the housing with respect to the stator. On the other hand, by arranging the position adjustment element between the stator and the end piece, the rotor can be moved closer to the end piece with respect to the stator.

[0011] According to an embodiment of the invention, the position adjustment element is detachably attached to both the part between the stator and the housing and the part between the stator and the end piece.

[0012] According to this structure, the rotor is movable relative to the stator on both the housing side and the end piece side.

[0013] The position adjustment element may be detachably provided at a free end, a center or a base part of the rotor.

[0014] The position adjustment element can be detachably attached to an end part or in the middle of the connecting part.

[0015] Preferably, the single-axis eccentric screw pump comprises several position adjustment elements.

[0016] According to this structure, the rotor can be moved in any axial direction with respect to the stator by changing the number of position adjusting elements to be mounted by a distance corresponding to the number of position adjusting elements.

[0017] Preferably, the axial lengths of the position adjustment elements are equal.

[0018] According to this structure, the rotor can be moved in the axial direction with respect to the stator by a distance proportional to the number of position adjusting elements to be attached and removed.

[0019] Preferably, an eccentricity of the rotor changes in the axial direction.

[0020] According to this structure, by changing the relative positional relationship between the rotor and the stator in the axial direction, the degree of eccentricity between the rotor and the stator is adjusted, and the mutual influence of the rotor and the stator is freely adjustable.

[0021] Preferably, the outer diameter of the rotor and / or the inner diameter of the through hole of the stator changes in the axial direction.

[0022] According to this structure, by changing the relative positional relationship between the rotor and the stator in the axial direction, the radial positional relationship between the rotor and the stator is adjustable, and the interference between the rotor and the stator is freely adjustable.

[0023] Preferably, the outer diameter of the rotor decreases in the axial direction, the inner diameter of the through hole of the stator decreases in accordance with the change in the outer diameter of the rotor, and the amount of eccentricity of the rotor increases from a large diameter side to a small diameter side of the rotor.

[0024] According to this design, the mutual influence between the rotor and the stator can be adjusted by changing the relative positional relationship between the rotor and the stator in the axial direction. However, it should be noted that the fluid transfer can be more stable because the change in the cavity volume is damped by the change in the eccentricity.

[0025] According to another form of the invention, the volumes of a plurality of cavities formed between the rotor and the stator by inserting the rotor into the stator are equal.

[0026] According to this structure, the fluid to be pumped is less likely to expand and contract in each cavity, and a stable pumping state can be achieved.

[0027] According to another form of the invention, the position adjusting member has a hollow cylindrical shape, and an inner peripheral surface of the position adjusting member is formed as an internal thread which is the same as or similar to an inner peripheral surface of the through hole of the stator.

[0028] According to this structure, the relative position of the stator with respect to the rotor can be changed in the axial direction, and the pump can have an additional function such as a defoaming function depending on the size of the inner diameter of the position adjusting member. EFFECT OF THE INVENTION

[0029] According to the present invention, the relative position of the stator with respect to the rotor in the axial direction is freely adjustable by the position adjusting member. BRIEF EXPLANATION OF THE FIGURES Fig. 1 is a sectional view showing a part of a single-axis progressive cavity pump according to a first embodiment. Fig. 2 is a sectional view showing a state in which a position adjusting member is removed from the Fig. 1 shown state. Fig. 3 is an illustrative view showing structures of a stator and a rotor in Fig. 1 are shown in simplified form. Fig. 4 is a sectional view showing a part of a single-axis progressive cavity pump according to a second embodiment. Fig. 5 is a sectional view showing a state in which a position adjusting member is removed from the Fig. 4 shown state. Fig. 6 is a sectional view showing a part of a single-axis progressive cavity pump according to a third embodiment. Fig. 7 is a sectional view showing a state in which a position adjusting member is removed from the Fig. 6 shown state. Fig. 8 is an illustrative view showing an inventive concept of a uniaxial progressive cavity pump according to a fourth embodiment. Fig. 9 is an illustrative view showing a state in which a position adjusting member is removed from the Fig. 8 shown state. Fig. 10 is an illustrative view showing an inventive concept of a uniaxial progressive cavity pump according to a fifth embodiment. Fig. 11 is an illustrative view showing a state in which a position adjusting member is removed from the Fig. 10 shown state. Fig. 12 is a sectional view showing a rotor and a connecting part of a single-axis progressive cavity pump according to a sixth embodiment. Fig. 13 is a sectional view showing a part of a single-axis progressive cavity pump according to another example of the sixth embodiment. Fig. 14 is a sectional view showing a state in which a position adjusting member in the Fig. 13 shown condition. Fig. 15 is a sectional view showing a part of a single-axis progressive cavity pump according to another example of the sixth embodiment. Fig. 16 is a sectional view showing a state in which a position adjusting member is Fig. 15 shown condition was added. Fig. 17 is a sectional view showing a part of a single-axis progressive cavity pump according to another example of the sixth embodiment. Fig. 18 is a sectional view illustrating a state in which a position adjusting member is Fig. 17 shown state is added. Fig. 19 is a sectional view showing a part of a single-axis progressive cavity pump according to a seventh embodiment. Fig. 20 is a sectional view showing a part of a single-axis progressive cavity pump according to an eighth embodiment. Fig. 21 is a side view showing a position adjusting member of a single-axis progressive cavity pump according to a ninth embodiment. Fig. 22 is a sectional view of a stator according to another embodiment. MODES OF OPERATION FOR IMPLEMENTING THE INVENTION

[0030] Embodiments of the present invention are described below with reference to the accompanying figures. It should be noted that the following description is merely exemplary and is not intended to limit the present invention, its application, or uses. (First embodiment)

[0031] As in Fig. 1, a single-axis eccentric screw pump according to a first embodiment comprises a rotor 1, a stator 2, a housing 3, an end piece 4 and a position adjusting element 5.

[0032] In the rotor 1, a shaft body made of a metallic material, such as stainless steel, is formed into a single-stage or multi-stage external thread with n-1 threads. Furthermore, the rotor 1 as a whole forms a virtual cone shape from one end to the other (see Fig. 3). In the present embodiment, although the cross-sectional shape of the rotor 1 is substantially a perfect circle (n=2), the outer diameter (cross-sectional area) of the rotor 1 gradually decreases from one end to the other end (in Fig. 3 from right to left).

[0033] The stator 2 has a hollow tubular shape extending from one end to the other and is made of an elastic material such as rubber or resin (e.g., silicone rubber or fluororubber) selected to match the fluid to be pumped. A through hole 2a of the stator 2 has the shape of a single- or multi-start internal thread with n threads, and the rotor 1 is inserted through the through hole 2a. The through hole 2a is shaped to have an overall virtual cone shape from one end to the other, matching the shape of the rotor 1 (see Fig. 3). That is, while the cross-sectional shape of the through hole 2a has the shape of a raceway, the inner diameter (cross-sectional area) of the through hole 2a gradually decreases from one end to the other end (from right to left in Fig. 3). In a state where the rotor 1 is inserted through the through hole 2a of the stator 2, a plurality of discharge spaces (cavities) 13 are formed between an inner surface of the through hole 2a of the stator 2 and an outer surface of the rotor 1. Here, the volumes of the discharge spaces 13 are equal. In addition, an outer cylinder 6 made of a metal material such as stainless steel is attached to an outer peripheral surface of the stator 2, and the stator 2 is prevented from deforming radially outward.

[0034] The shaft center of the rotor 1 and the shaft center of the stator 2 are eccentric to each other, and the degree of eccentricity increases from one end to the other. Consequently, the volumes of the discharge chambers 13 are identical.

[0035] Furthermore, the rotor 1 and the stator 2 as a whole form a virtual cone shape. When the rotor 1 is moved to the left relative to the stator 2, the contact pressure between the inner surface forming the through hole 2a of the stator 2 and the outer surface of the rotor 1 increases. Consequently, the interference between the stator 2 and the rotor 1 can be increased. Conversely, when the rotor 1 is moved to the right relative to the stator 2, the interference between the stator 2 and the rotor 1 can be decreased.

[0036] Note that although in this example the outer diameter of the rotor 1 and the inner diameter of the through hole 2a of the stator 2 gradually decrease from one end to the other, it is sufficient if at least one of them has such a structure.

[0037] The housing 3 is made of a metal material such as stainless steel in a hollow cylindrical shape, and one end part thereof is connected to one end side of the stator 2. A stepped terminal receiving part 7 with an enlarged inner diameter is formed on one end surface of the housing 3. One end part of the outer cylinder 6 and a terminal part 11 of the position adjusting member 5 described later are connected to the terminal receiving part 7. A connecting pipe (not shown) is connected to the housing 3, and a fluid is supplied thereto. In addition, a connecting part 8 is arranged in the housing 3. A drive shaft (not shown) extending from a drive source is connected to one end side of the connecting part 8. The rotor 1 is connected to the other end part of the connecting part 8. Thereby, the driving force from the drive source is transmitted to the rotor 1, and the rotor 1 is rotated.

[0038] The end piece 4 is made of a metal material such as stainless steel, and one end portion thereof is connected to the other end side of the stator 2. A stepped connection receiving portion 9 with an enlarged inner diameter is formed on one end surface of the end piece 4. The other end portion of the outer cylinder 6 and the later-described connecting portion 11 of the position adjusting member 5 are connected to the connection receiving portion 9. Furthermore, the end piece 4 forms an outlet for discharging a fluid flowing through the through hole 2a of the stator 2.

[0039] The position adjusting member 5 is made of a metal material such as stainless steel in a hollow cylindrical shape and is arranged between one end part of the outer cylinder 6 and one end part of the housing 3 (in this example, four position adjusting members 5 are connected). One end opening of the position adjusting member 5 is formed by a stepped connection receiving part 10 with an enlarged inner diameter. The other end opening of the position adjusting member 5 is formed by a stepped connecting part 11 with a reduced outer diameter. The position adjusting members 5 are connected to each other in a sealed state by coupling the connecting part 11 to the connection receiving part 10 via a gasket 12.The position adjusting member 5 and the housing 3 are connected to each other in a sealed state by connecting the connection receiving part 7 of the housing 3 to the connecting part 11 of the position adjusting member 5 via the gasket 12. The position adjusting member 5 and the outer cylinder 6 are connected to each other by connecting one end part of the outer cylinder 6 to the connection receiving part 10 of the position adjusting member 5. At this time, a part of the stator 2 is arranged between the connection receiving part 10 of the position adjusting member 5 and one end part of the outer cylinder 6 to achieve a sealed state. The position adjusting member 5 is movable between the end part 4 and the stator 2.In this case, the position adjusting member 5 and the end piece 4 are connected in a sealed state by coupling the connecting part 11 of the position adjusting member 5 to the connection receiving part 9 of the end piece 4 via the gasket 12. Furthermore, the position adjusting member 5 and the outer cylinder 6 of the stator 2 are connected to each other by connecting the other end part of the outer cylinder 6 to the connection receiving part 10 of the position adjusting member 5. At this time, a part of the stator 2 is interposed between the connection receiving part 10 of the position adjusting member 5 and the other end part of the outer cylinder 6 to achieve a sealed state.

[0040] In the single-axis eccentric screw pump with the structure explained above, the single-axis eccentric screw pump is initially, as for example in Fig. 1, in a state in which four position adjusting elements 5 are connected between the stator 2 and the housing 3, with a desired interference between the rotor 1 and the stator 2. In this state, when power is transmitted from a drive system (not shown) via the connecting part 8 and the rotor 1 rotates, the fluid supplied into the housing 3 is conveyed to the end piece 4 via the conveying spaces (cavities) 13 formed between the stator 2 and the rotor 1.

[0041] When the inner surface forming the through hole 2a of the stator 2 is worn by use and the interference of the stator 2 with the rotor 1 becomes small, one of the four position adjusting elements 5 connected between the stator 2 and the housing 3 is displaced as shown by an arrow in Fig. 1, removed and inserted between the stator 2 and the end piece 4, as indicated by an arrow in Fig. 2. As a result, the relative position of the stator 2 with respect to the rotor 1 is shifted by the axial length of a moving position adjusting member 5. That is, the position where the rotor 1 is in sliding contact with the inner surface forming the through hole 2a of the stator 2 is changed to a position with a larger cross-sectional area, and the interference between the stator 2 and the rotor 1 can be corrected to be larger.

[0042] Later, when the stator 2 is further worn, the remaining position adjustment elements 5 positioned between the stator 2 and the housing 3 can be removed one by one and inserted between the stator 2 and the end piece 4. Note that the wear state of the stator 2 can be determined by visually observing the fluid flow state or simply automatically detected by the rotational speed of the rotor 1.

[0043] In this way, the interference of the stator 2 can be improved to an appropriate level at any time by increasing the number of position adjustment elements 5 that move between the stator 2 and the housing 3 and between the stator 2 and the end piece 4, in accordance with the degree of wear of the stator 2. The improvement of the interference can be continued until all position adjustment elements 5 have been replaced.

[0044] Furthermore, the conditions for achieving a desired interference between the rotor 1 and the stator 2 vary depending on the type of fluid to be pumped and the environment to be used. Therefore, a reference condition can be determined, and the position adjustment element 5 can be mounted between the stator 2 and the housing 3 and between the stator 2 and the end piece 4, so that the rotor 1 and the stator 2 are in positions where a desired interference can be achieved at that time.

[0045] For example, if the ambient temperature is higher than a certain reference temperature (normal temperature from 15°C to 25°C, e.g. 20°C), it is necessary to consider the expansion and the like of the stator 2. Therefore, the number of position adjusting elements 5 between the stator 2 and the housing 3 can be increased to Fig. 1 and Fig. 2 to move the rotor 1 to the right relative to the stator 2. This can prevent the stator 2 from over-interfering with the rotor 1, and the fluid can be conveyed accordingly. On the other hand, the number of position adjustment elements 5 between the stator 2 and the end piece 4 can be increased when the ambient temperature is lower than the reference temperature to prevent a reduction in the interference between the stator 2 and the rotor 1.

[0046] Alternatively, if the fluid has a higher viscosity than a certain reference viscosity (e.g. the viscosity of a standard solution for calibration), the number of position adjustment elements 5 between the stator 2 and the housing 3 can be increased in order to Fig. 1 and Fig. 2 to move the rotor 1 to the right relative to the stator 2, so that the interference can be suppressed to facilitate the conveying of the fluid. On the other hand, if the fluid has a lower viscosity than a certain reference viscosity, the number of position adjustment elements 5 between the stator 2 and the end piece 4 can be increased to increase the interference, so that leakage of the fluid from the conveying chamber 13 can be prevented.

[0047] The following effects can be achieved by the single-axis eccentric screw pump with the structure described above. (1) Even if the stator 2 wears out, the interference between the stator 2 and the rotor 1 can be restored to the original state only by changing the mounting location of the position adjusting member 5 from between the stator 2 and the housing 3 to between the stator 2 and the end piece 4. (2) By changing the mounting location of the position adjusting member 5, the interference between the stator 2 and the rotor 1 can be adjusted to an appropriate value according to different conditions such as the viscosity of the fluid and the ambient temperature, and the conveying state of the fluid can be maintained in a favorable state. (3) Since it is only necessary to displace the position adjusting element 5 between the stator 2 and the housing 3 or between the stator 2 and the end piece 4, the interference between the stator 2 and the rotor 1 can be easily adjusted. (Second embodiment)

[0048] As in Fig. 4, a single-axis progressive cavity pump according to a second embodiment has substantially the same structure as that of the first embodiment except for the following points.

[0049] In the second embodiment, a rotor 1 has the same cross-sectional area from one end to the other. Furthermore, a through-hole 2a of a stator 2 also has the same cross-sectional area from one end to the other. In an initial use state, the rotor 1 includes a first portion located in the through-hole 2a of the stator 2 and a second portion located in a position adjustment element 5.

[0050] According to the single-axis progressive cavity pump of the second embodiment, when a part of the rotor 1 is damaged during use, for example, by a fluid, the position adjusting member 5 is displaced, and the position in which the rotor 1 is in sliding contact with the stator 2 is adjusted as shown in Fig. 5. This allows the fluid flow to be restored to a suitable state.

[0051] When the amount of eccentricity of the rotor 1 in the axial direction of the stator 2 is changed, the volume of the discharge chamber 13 in the axial direction can be decreased or increased by shifting the position of the rotor 1 in the axial direction. For example, when the rotation center of the rotor 1 is gradually brought closer to the shaft center of the stator 2 toward the discharge direction of the fluid in the axial direction of the stator 2, the ratio of the cross-sectional area occupied by the discharge chamber 13 can be decreased by moving the rotor 1 in the discharge direction. That is, the volume of the discharge chamber 13 can be gradually decreased in the discharge direction. In addition, by moving the rotor 1 in a direction opposite to the discharge direction, the ratio of the cross-sectional area occupied by the discharge chamber 13 can be increased. (Third embodiment)

[0052] As in Fig. 6, a single-axis progressive cavity pump according to a third embodiment has substantially the same structure as those of the first embodiment and the second embodiment except for the following points.

[0053] In the third embodiment, a rotor 1 has the same cross-sectional area from one end to the other, similar to the second embodiment. Furthermore, a through hole 2a of a stator 2 also has the same cross-sectional shape from one end to the other. However, it should be noted that the stator 2 differs in that the length of the stator 2 is longer than that of the second embodiment. Here, the length of the stator 2 is approximately three times that of the second embodiment.

[0054] In the initial phase, the single-axis eccentric screw pump according to the third embodiment is used, in which the rotor 1 is inserted only at one end side of the stator 2 (here about two gears indicated by arrows in Fig. 6). When the stator 2 wears out, a position adjusting element 5 between the stator 2 and a housing 3 is removed, and as shown in Fig. As shown in Fig. 7, the position adjusting member 5 is moved between the stator 2 and an end piece 4 to further increase the insertion depth of the rotor 1 into the stator 2 (here, the insertion depth is increased from approximately two turns of the through hole 2a to three turns of the through hole 2a). As a result, a new, unworn portion can be added to the contact area between an inner surface forming the through hole 2a of the stator 2 and an outer surface of the rotor 1, and the conveying state of the fluid can be restored. Since a portion where the stator 2 is not worn can be used, the conveying state of the fluid can be improved compared to the first embodiment in which the worn part is continuously used. (Fourth embodiment)

[0055] A single-axis progressive cavity pump according to a fourth embodiment has substantially the same structure as that of the first embodiment except for the following points.

[0056] As in Fig. As shown schematically in Figure 8, a rotor 1 is shaped so that the cross-sectional area from one end to the other end (from the right side to the left side in Fig. 8) gradually decreases (in practice, the rotor 1 is molded in a shape having one or more external threads with n-1 threads similar to the first embodiment and the like). Meanwhile, the cross-sectional area of ​​the through hole 2a of the stator 2 is the same in each section in the axial direction.

[0057] According to the uniaxial progressive cavity pump of the fourth embodiment, the discharge chambers 13 gradually increase in size toward the downstream side as the rotor 1 is rotated to discharge the fluid. This allows negative pressure to be generated in the discharge chambers 13 to separate and remove gas dissolved in the fluid in the form of air bubbles. To increase the negative pressure in the discharge chamber 13 and facilitate the generation of even more air bubbles, as shown in Fig. 9, a position adjusting element 5 arranged between an end piece 4 and the stator 2 is inserted between the stator 2 and a housing (not shown). This retracts the rotor 1 relative to the stator 2 in order to reduce the volume of the Fig. 9 not shown) and the gas dissolved in the fluid can be removed more easily. (Fifth embodiment)

[0058] A single-axis progressive cavity pump according to a fifth embodiment has substantially the same structure as that of the first embodiment except for the following points.

[0059] As in Fig. 10, the cross-sectional area of ​​a rotor 1 gradually increases from one end to the other end (in Fig. 10 from right to left). At the same time, the cross-sectional area of ​​a through hole 2a of a stator 2 is the same in each section in the axial direction.

[0060] According to the uniaxial progressive cavity pump of the fifth embodiment, air bubbles contained in the fluid can be pressurized and dissolved in the fluid when the rotor 1 is rotated to convey the fluid. To further pressurize the fluid and dissolve the air bubbles in the fluid, Fig. 11, a position adjusting element 5 arranged between an end piece 4 and the stator 2 can be moved between the stator 2 and a housing (not shown). As a result, the front end side of the rotor 1 with the large outer diameter can be inserted into the housing (shown in Fig. 11 not shown) through hole 2a of the stator 2, and the volume of a discharge chamber 13 can be reduced to more easily dissolve the air bubbles in the fluid.

[0061] While in the fourth and fifth embodiments only the cross-sectional area of ​​the rotor 1 is changed, it should be noted that a similar effect can be achieved by changing the cross-sectional area of ​​the through hole 2a of the stator 2 or by changing both. (Sixth Embodiment)

[0062] A single-axis progressive cavity pump according to a sixth embodiment has substantially the same structure as that of the first embodiment except for the following points.

[0063] As it is in Fig. As shown in Figure 12, a position adjustment element 5 can be detachably attached to a rotor 1 at the free end, the center, the base (connecting part with the connecting part 8), and the center of the connecting part 8. The position at which the position adjustment element 5 is attached and detached can be at three, two, or one of these four positions.

[0064] Fig. 13 shows an example in which the position adjusting member 5 is detachably provided at the connecting part between the rotor 1 and the connecting part 8. A coupling part 15 is coupled to one end part of the connecting part 8 by a connecting pin 14. A shaft part 15a protrudes from an end surface of the coupling part 15, and a through hole 15b is formed in the center of the shaft part 15a. Meanwhile, an engaging hole 1a is formed in one end part of the rotor 1, into which the shaft part 15a of the coupling part 15 is inserted. A keyway is formed between the shaft part 15a and the engaging hole 1a, and a key 16 is arranged in the keyway.By screwing a screw 17 into the coupling part 15, the outer diameter of the shaft part 15a expands, an outer peripheral surface of the shaft part 15a of the coupling part 15 is brought into pressure contact with an inner peripheral surface of the engagement hole 1a of the rotor 1, and the parts are coupled together. In addition, the presence of the key 16 prevents the rotor 1 from rotating relative to the coupling part 15. When changing the sliding contact position of the rotor 1 relative to the stator 2, the position adjusting member 5 can be used as shown in FIG. Fig. 14 may be arranged between the clutch part 15 and the rotor 1. In this case, the key 16 may be replaced to prevent rotation between the position adjusting member 5 and the shaft part 15a of the clutch part 15. Consequently, the pressure contact force between an inner surface forming a through hole 2a of the stator 2 and an outer surface of the rotor 1 can be increased if the cross-sectional area of ​​the rotor 1 is designed to increase in cross section toward the base end.

[0065] Fig. 15 shows an example in which the position adjusting member 5 is detachably provided on the rotor 1. A front end part and a part of a base end side of the rotor 1 are formed from the position adjusting member 5, and these parts are fixed by a screw 17 inserted from the front end side of the rotor 1. Here, one position adjusting member 5 corresponds to one revolution of the rotor 1. When the sliding contact position of the rotor 1 relative to the stator 2 is changed as shown in Fig. As shown in Figure 16, the position adjustment member 5 provided at the tip end of the rotor 1 can be removed and attached to the base end side. As a result, the sliding contact position of the rotor 1 with respect to the stator 2 can be shifted by one gear from the tip end side to the base end side. Consequently, if the cross-sectional area of ​​the rotor 1 is designed to increase in cross section toward the base end, the pressure contact force between the inner surface forming the through hole 2a of the stator 2 and the outer surface of the rotor 1 can be increased.

[0066] Fig. 17 shows an example in which the position adjusting element 5 is detachably provided in the connecting part 8. A part of the connecting part 8 is formed by the position adjusting elements 5, which are coupled to each other and detachably. Each position adjusting element 5 includes a threaded bolt 5a in the center of one of the end faces and a threaded hole 5b in the center of the other end face. By screwing the threaded bolt 5a into the threaded hole 5b, the position adjusting elements 5 can be connected to each other. By increasing the number of position adjusting elements 5 to be coupled, the rotor 1 can be moved relative to the stator 2 in the axial direction toward the head side. Fig. 18, a position adjustment element 5 is added to the three in Fig. 17 coupled position adjusting elements 5 are added, so that a total of four position adjusting elements 5 are coupled. This allows the rotor 1 to be moved by an axial length of the position adjusting element 5. If the cross-sectional area of ​​the rotor 1 is designed to increase in cross section toward the base end or entrance end, the pressure contact force between the inner surface forming the through hole 2a of the stator 2 and the outer surface of the rotor 1 can be increased. (Seventh Embodiment)

[0067] A single-axis progressive cavity pump according to a seventh embodiment has substantially the same structure as that of the first embodiment except for the following points:

[0068] As in Fig. 19, the position adjusting elements 5 have different axial lengths. Here, the position adjusting element 5 includes four of the first to fourth position adjusting elements, and the ratio of their axial lengths is 1:2:3:4. Note, however, that the number, length, and length ratio of the position adjusting elements 5 are freely adjustable.

[0069] According to the uniaxial progressive cavity pump of the seventh embodiment, by appropriately combining the position adjusting elements 5, the degree of freedom in adjusting the position of the rotor 1 relative to the stator 2 can be further increased. That is, from an initial state in which a first position adjusting element 5-1 to a fourth position adjusting element 5-4 are arranged between the stator 2 and the casing 3 in this order, only the first position adjusting element 5-1 is displaced between the stator 2 and the end piece 4. Similarly, the second position adjusting element 5-2, the third position adjusting element 5-3, and the fourth position adjusting element 5-4 are displaced one by one in sequence. Thereafter, the position adjusting elements 5 are displaced in combinations of the respective position adjusting elements 5.This makes it possible to extend the range of position adjustment of the rotor 1 compared to a case where all position adjustment elements 5 have the same length. (Eighth Embodiment)

[0070] A single-axis eccentric screw pump according to an eighth embodiment has substantially the same structure as the first embodiment except for the following points:

[0071] As in Fig. 20, a position adjusting member 5 includes a cylindrical portion 5A made of a metal material such as stainless steel, and an inner portion 5B disposed on an inner side of the cylindrical portion 5A and made of a material similar to that of a stator 2. A through hole 5C having one or more internal threads with n threads similar to the stator 2 is formed in the inner portion 5B. For example, the through hole 5C of the position adjusting member 5 may have a smaller inner diameter than that of the stator 2, and the position adjusting member 5 may be disposed between the stator 2 and an end piece 4.This makes it possible to obtain a structure in which, in addition to adjusting the axial positional relationship between the rotor 1 and the stator 2, the remaining air bubbles in the fluid are released by pressurizing the fluid only by mounting the position adjusting member 5, without providing any special machining to the stator 2. On the other hand, the through hole 5C of the position adjusting member 5 may have a larger inner diameter than that of the stator 2, and the position adjusting member 5 may be arranged between the stator 2 and the end piece 4. This makes it possible to obtain a structure in which, in addition to adjusting the axial positional relationship between the rotor 1 and the stator 2, the air bubbles dissolved in the fluid are separated and removed as gas bubbles only by mounting the position adjusting member 5, without providing any special machining to the stator 2.Furthermore, the stator 2 can be replaced with the plurality of position adjusting elements 5 having the above-described structure. Therefore, it is possible to replace only the damaged position adjusting element 5, which is economical. (Ninth Embodiment)

[0072] A single-axis eccentric screw pump according to a ninth embodiment has substantially the same structure as the first embodiment except for the following points:

[0073] As in Fig. 21, a position adjusting member 5 may be divided into multiple parts in the circumferential direction. Here, the position adjusting member 5 is circumferentially divided into two parts: a first position adjusting part 18 and a second position adjusting part 19. Both the first position adjusting part 18 and the second position adjusting part 19 have a semi-cylindrical shape, and a radially outwardly projecting part 20 is formed on the facing surfaces. The outwardly projecting parts are connected to each other by a screw 17 with a gasket 12 interposed therebetween. According to this structure, it is possible to easily attach or detach only the position adjusting member 5 by tightening or loosening the screw 17.

[0074] Note that the present invention is not limited to the structures described in the above-explained embodiments, and various modifications may be made.

[0075] While examples including one to four position adjusting members 5 have been described in the above-described embodiments, the number of position adjusting members 5 is not particularly limited and may be five or more. In a case where only one position adjusting member 5 is provided, it is possible to provide the position adjusting member 5 only between the stator 2 and the housing 3 or between the stator 2 and the end piece 4 and displace the position adjusting member 5 to the other position. It is also possible to detachably attach and detach the position adjusting member 5 only to a part between the stator 2 and the housing 3 and to a part between the stator 2 and the end piece 4.Note, however, that it is easier to displace the position adjusting element 5 between the part between the stator 2 and the housing 3 and the part between the stator 2 and the end piece 4 because the positional relationship can be adjusted without changing the overall length of the pump.

[0076] While the position adjusting member 5 is made of metal in the above-described embodiments, the position adjusting member 5 may also be made of synthetic resin or rubber. If the position adjusting member 5 is made of synthetic resin or rubber, it can be easily removed by cutting without disassembling the pump. If the position adjusting member 5 is divided into multiple parts in the circumferential direction as described above, disassembly of the pump is not necessary even when the position adjusting member 5 is attached.

[0077] In the embodiment explained above, the volume of the conveying chamber 13 can be increased or decreased toward one end side, for example, by gradually decreasing or, on the contrary, increasing the pitch of the screw shapes of the rotor 1 and the stator 2 toward one end side.

[0078] While the outer diameter of the rotor 1 is gradually reduced toward the end piece 4 in the above-described embodiment, the outer diameter can also be gradually increased. While the eccentricity of the rotor 1 relative to the stator 2 is increased toward the end piece 4 in the above-described embodiment, the eccentricity can also be reduced.

[0079] While the position adjusting member 5 is mounted between the stator 2 and the housing 3 in the above-described embodiment, the position adjusting member 5 may be mounted between split housings 3. Alternatively, the position adjusting member 5 may be attached to an end portion or a middle portion of the stator 2. In short, the position adjusting member 5 may be detachably attached to at least one end portion or the middle of the rotor 1, the stator 2, the housing 3, or the connecting part 8. The position adjusting member 5 may be provided in each of the rotor 1 and the housing 3, the stator 2 and the housing 3, and the like.

[0080] While the thickness of the stator 2 is configured to change in the axial direction in the above-described embodiment, the thickness of the stator 2 is preferably configured to be uniform and not change. Fig.Figure 22 is a longitudinal sectional view of the stator 2. An inner surface of the outer cylinder 6, made of a metallic material such as stainless steel, is formed as a single- or multi-stage internal thread with n pitches. The stator 2, made of an elastic material such as rubber with a larger thermal expansion coefficient than the outer cylinder 6, has a uniform overall thickness, so that the thickness in the cross section is uniform at every point, and the thickness of each cross section displaced in the axial direction is uniform at every cross section.

[0081] In the uniaxial progressive cavity pump with the stator 2 having such a structure, the interaction with the rotor 1 does not change even when the temperature of the fluid or the ambient atmosphere changes. That is, because the thickness of the stator 2 in the cross section is the same at every position, the pressure contact force acting on the outer surface of the rotor 1 does not increase or decrease at any position in the cross section. Because the thickness is the same at every cross section in the axial direction of the stator, the friction does not increase or decrease at any position in the axial direction when the rotor 1 rotates. Accordingly, the interaction of the stator 2 with the rotor 1 can be appropriately adjusted regardless of changes in the temperature of the fluid and the ambient atmosphere, and the rotation state of the rotor 1 can be stabilized.Note that the thickness of stator 2 can be determined depending on the magnitude of the temperature change of the fluid and the ambient atmosphere. In other words, the thickness can be set thin when the temperature change is large, and the thickness can be increased when used under small temperature changes. LIST OF REFERENCE SYMBOLS 1 rotor 2 Stator 3 housings 4 End piece 5 Position adjustment element 6 outer cylinders 7 Connection receptacle 8 Connecting part 9 Connection receptacle 10 Connection receptacle 11 Connection part 12 Seal 13 Production room 14 connecting pin 15 Coupling part 16 key 17 Screw 18 first position adjustment part 19 second position adjustment part 20 protruding part.

Claims

[1] Single-axis eccentric screw pump with: a rotor (1) with a shaft body with external thread; a stator (2) with an internally threaded through-bore through which the rotor (1) is inserted; a housing (3) connectable to one end of the stator (2); an end piece (4) which can be connected to the other end side of the stator (2); and a position adjusting element (5) which adjusts a relative position of the stator (2) relative to the rotor (1) in an axial direction, wherein the position adjusting element (5) is detachably attached to both the part between the stator (2) and the housing (3) and the part between the stator (2) and the end piece (4). [2] Single-axis eccentric screw pump according to claim 1, further comprising a connecting part (8) which transmits power from a drive source to the rotor (1), wherein the position adjusting element (5) is detachably provided at an end part or in the middle of the rotor (1), the stator (2), the housing (3) and / or the connecting part (8). [3] Single-axis eccentric screw pump according to one of claims 1 or 2, wherein the position adjusting element (5) is detachably provided at a free end, a center or a base part of the rotor (1). [4] A single-axis eccentric screw pump according to claim 2, wherein the position adjusting member (5) is detachably attachable to an end part or in the middle of the connecting part (8). [5] Single-axis eccentric screw pump according to one of claims 1 to 4, further comprising a plurality of position adjusting elements (5). [6] Single-axis eccentric screw pump according to claim 5, wherein the axial lengths of the position adjusting elements (5) are equal. [7] Single-axis eccentric screw pump according to one of claims 1 to 6, wherein an eccentricity of the rotor (1) changes in the axial direction. [8] Single-axis eccentric screw pump according to one of claims 1 to 7, in which the outer diameter of the rotor (1) and / or the inner diameter of the through-bore of the stator (2) changes in the axial direction. [9] Single-axis eccentric screw pump according to one of claims 7 or 8, wherein: an outer diameter of the rotor (1) decreases in the axial direction; an inner diameter of the through hole of the stator (2) decreases in accordance with the change in the outer diameter of the rotor (1); and an amount of eccentricity of the rotor (1) increases from a large diameter side to a small diameter side of the rotor (1). [10] Single-axis eccentric screw pump with: a rotor (1) with a shaft body with external thread; a stator (2) with an internally threaded through-bore through which the rotor (1) is inserted; a housing (3) connectable to one end of the stator (2); an end piece (4) which can be connected to the other end side of the stator (2); and a position adjusting element (5) which adjusts a relative position of the stator (2) relative to the rotor (1) in an axial direction, wherein: an outer diameter of the rotor (1) decreases in the axial direction; an inner diameter of the through hole of the stator (2) decreases in accordance with the change in the outer diameter of the rotor (1); and an amount of eccentricity of the rotor (1) increases from a large diameter side to a small diameter side of the rotor (1), and the volumes of several cavities formed between the rotor (1) and the stator (2) by inserting the rotor (1) into the stator (2) are equal. [11] Single-axis eccentric screw pump with: a rotor (1) with a shaft body with external thread; a stator (2) with an internally threaded through-bore through which the rotor (1) is inserted; a housing (3) connectable to one end of the stator (2); an end piece (4) which can be connected to the other end side of the stator (2); and a position adjusting element (5) which adjusts a relative position of the stator (2) relative to the rotor (1) in an axial direction, wherein the position adjusting element (5) has a hollow cylindrical shape and an inner peripheral surface of the position adjusting element (5) is formed as an internal thread which is the same as or similar to an inner peripheral surface of the through hole of the stator (2).

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