WO2020250720A1

WO2020250720A1 - Connection shaft and uniaxial eccentric screw pump

Info

Publication number: WO2020250720A1
Application number: PCT/JP2020/021500
Authority: WO
Inventors: 教晃榊原; 剛志森田
Original assignee: 兵神装備株式会社
Priority date: 2019-06-11
Filing date: 2020-05-30
Publication date: 2020-12-17
Also published as: KR20220017894A; CN113785124A; JPWO2020250720A1; TW202045820A

Abstract

The purpose of the present invention is to provide a connection shaft having low flexural rigidity and high torsional rigidity. A connection shaft (10) having flexibility and connecting a first member and a second member comprises a twisted part (12) in at least one section thereof, in which cross sections perpendicular to the axial direction of the connection shaft (10) are shaped in a continuously twisting manner toward the axial direction or are shaped in a twisting manner so as to turn in an intermittently stepped shape. Cross-sectional second moments of area at a cross section differ between a first direction (widthwise direction) which is perpendicular to the axial direction and in which the cross-sectional second moment of area at the cross section (13) is minimal, and a second direction (lengthwise direction) perpendicular to the first direction at the same cross section (13).

Description

Connecting shaft and uniaxial eccentric screw pump

The present invention relates to a connecting shaft and a uniaxial eccentric screw pump. More specifically, the present invention relates to a connecting shaft that connects the first member and the second member and transmits power between them, and a uniaxial eccentric screw pump using the connecting shaft.

Conventionally, in order to enable eccentric rotation of the rotor of a uniaxial eccentric screw pump, a round bar-shaped flexible connecting shaft (corresponding to a flexible drive shaft) has been used between the drive side rotating portion and the rotor. (For example, Patent Document 1).

Further, a flexible connecting shaft having a shape in which flat plate-shaped members with slits are orthogonal to each other is known (for example, Patent Document 2).

JP 2012-154215 JP-A-2014-105827

By the way, the connecting shaft of Patent Document 1 needs to be displaced at both ends in order to rotate the rotor eccentrically. Therefore, the connecting shaft is required to have flexibility and low flexural rigidity. When this flexural rigidity is high, there is a problem that the posture of the rotor is tilted in the stator due to the reaction force (also referred to as restoring force) of the connecting shaft. In this way, when the rotor is tilted, the rotor is strongly pressed near the insertion port of the stator, so that the transfer space inside the stator is deformed and the discharge performance is deteriorated even though the inside of the stator is not worn. is there.

Further, the connecting shaft is required to have high torsional rigidity in order to accurately transmit the rotation angle of the drive source to the rotor when the rotation of the rotor is started or stopped. If this torsional rigidity is low, the rotation angle of the drive source cannot be properly transmitted to the rotor when the rotor is started or stopped, and the responsiveness of pump discharge start and stop becomes poor, or the stick-slip phenomenon occurs. There is a problem that abnormal noise and pulsation of discharge occur.

Generally, materials and shapes with high flexural rigidity have high torsional rigidity, and conversely, materials and shapes with low flexural rigidity have a correlation of low torsional rigidity, so they are required for ideal connecting shafts. There was no connecting shaft of material or shape that met both requirements for torsional rigidity and low bending rigidity.

Therefore, the conventional connecting shaft is made of a material such as titanium alloy or engineering plastic, which has a bending rigidity enough to be slightly bent while ensuring a certain degree of torsional rigidity, and has no problem in terms of strength. A round bar is used. By lengthening this round bar, even if the bending angle is small, it can be bent by the length of the displacement of the eccentric rotation, so that the reaction force is reduced. For this reason, in the uniaxial eccentric screw pump adopting the conventional connecting shaft, there is a problem that the length of the entire pump becomes long and the size becomes large. Further, as the connecting shaft becomes longer, the twist angle of the entire shaft with respect to torque also increases, and there remains a problem that the responsiveness of discharge does not improve so much. Further, along with this, the casing accommodating the above-mentioned connecting shaft is also increased in size, and when the uniaxial eccentric screw pump is stopped, the problem that the residual amount of fluid in the casing increases and the installation space is secured. There was also the problem that it became difficult to do.

Further, as the connecting shaft in Patent Document 2, a flat plate-shaped member having low flexural rigidity is orthogonalized in only one direction to correspond to displacement in all directions. However, the flat plate shape has a low torsional rigidity, and there is a problem that a force in the twisting direction acts on the flat plate-shaped member when a rotational torque is applied, and the flat plate-shaped member is twisted.

Further, since a force due to displacement acts from all directions of 360 ° for each rotation position, when a force is applied to the flat plate-shaped member from a direction other than the vertical direction, which is the direction most easily bent, the rotor of the uniaxial eccentric screw pump and The reaction force on the stator fluctuates greatly with each angle. As a result, there is a problem that the posture of the rotor wobbles in the stator, the shape and volume of the cavity are changed, the discharge accuracy is deteriorated, and pulsation is caused.

Therefore, in order to solve the above-mentioned problems, the present invention provides a compact connecting shaft having flexural rigidity and flexibility that allows displacement in the bending direction, and high torsional rigidity in the torsional direction. An object of the present invention is to provide a uniaxial eccentric screw pump that does not generate abnormal noise or pulsation of discharge due to a connecting shaft.

The connecting shaft of the present invention provided to solve the above-mentioned problems has flexibility and connects the first member and the second member, and has a cross section orthogonal to the axial direction of the connecting shaft. At least a part of the twisted shape portion is provided with a twisted shape portion having a shape that is continuously twisted as the shape is oriented in the axial direction or a shape that is twisted so as to swivel in an intermittent step shape, and a moment of inertia of area on the cross section. However, it is characterized in that it differs between the first direction orthogonal to the axial direction and the minimum moment of inertia of area in the cross section and the second direction orthogonal to the first direction on the same cross section. ..

The connecting shaft of the present invention has a cross-sectional shape orthogonal to the axial direction of the connecting shaft that is continuously twisted toward the axial direction or twisted so as to swivel in an intermittent step shape. It has a twisted shape at least in part. That is, when the connecting shaft rotates, a part of the moment in the twisting direction is converted into an axial force or the like due to the shape twisted in the initial state, so that the torsional rigidity of the connecting shaft is substantially improved. Therefore, by connecting the connecting shaft of the present invention to a drive source such as a motor, it is possible to accurately transmit the rotation angle of the drive source with good responsiveness.

The connecting shaft of the present invention has the direction in which the moment of inertia of area on the cross section is minimized as the first direction, the length in the first direction, and the second crossing on the same cross section with respect to the first direction. It has cross-sectional shapes with different lengths in the direction. That is, since the moment of inertia of area in the first direction is minimized, the connecting shaft of the present invention is more likely to be displaced in the first direction than in the second direction at each cross-sectional position of the connecting shaft. Then, since the shape of the cross section is a shape that is continuously twisted toward the axial direction or a shape that is twisted so as to swivel in an intermittent step shape, the displacement in any direction of 360 ° due to the eccentric rotation. Can also be handled. Since it has such characteristics, it can be suitably used as an eccentric rotation shaft of various devices (for example, a pump, a compressor, a dispenser, a reciprocating mechanism, etc.) that require eccentric rotation.

The connecting shaft of the present invention is likely to be displaced in the first direction in which the moment of inertia of area is minimized, and the displacement in the second direction in which the moment of inertia of area is large is restricted. That is, the connecting shaft of the present invention has appropriate flexibility and high torsional rigidity because the first direction and the second direction change sequentially in the circumferential direction as the connecting shaft turns. It is possible to provide a connecting shaft that satisfies the requirements of.

Further, the connecting shaft of the present invention can tolerate displacement due to eccentricity. Therefore, the connecting shaft of the present invention can tolerate displacement due to eccentricity even if it is connected without using a universal joint. Therefore, if the connecting shaft of the present invention is used, it can be connected without providing a sliding portion on the connecting shaft, so that foreign matter can be prevented from being mixed due to wear or the like. Therefore, the connecting shaft of the present invention can be suitably used as a connecting shaft for devices such as those for food processing and pharmaceuticals, in which contamination with foreign substances is a problem.

As described above, since the connecting shaft of the present invention has both physical properties with low flexural rigidity and physical properties with high torsional rigidity, it is possible to design a shorter length without lowering the torsional resistance to rotational torque. Therefore, the device using the connecting shaft of the present invention can be miniaturized, and a highly versatile device that does not depend on the installation space can be provided.

The connecting shaft of the present invention is within the cross-sectional shape when the torsional axis of the connecting shaft is viewed in cross section at any position in the axial direction, and the cross-sectional shape passes through the torsional axis position and is said to be the first. A shape that is line-symmetric with respect to the first axis along one direction, a shape that passes through the torsion axis position and is line-symmetric with respect to the second axis along the second direction, and a shape that is point-symmetric with respect to the torsion axis. It is preferably at least one shape.

For the connecting shaft of the present invention, a shape such as a rectangle, an ellipse, a rounded corner, a parallelogram, or a rhombus can be preferably adopted as the cross-sectional shape. According to such a configuration, the connecting shaft can be easily manufactured and processed.

The connecting shaft of the present invention preferably has a total twist angle of a twisted shape portion of ± 20 degrees, which is a multiple of 180 degrees.

Since the connecting shaft of the present invention has such a configuration, the first direction that is most easily bent corresponds to the bending direction of one rotation (360 °) evenly in half rotation (180 °) about the rotation axis. Since there is no extra angle except for the error, the fluctuation of the reaction force is stable. Therefore, the rotational posture of the first member or the second member connected to both ends of the connecting shaft is stable, and abnormal noise and vibration caused by the unstable rotational posture of the first member or the second member can be reduced.

The uniaxial eccentric screw pump of the present invention provided to solve the above-mentioned problems is capable of inserting the rotor into a rotor composed of a drive side rotating portion that is rotated by the power of a drive machine and a male screw type shaft body. A stator whose inner peripheral surface is formed in a female screw shape and the drive side rotation so that the rotor can rotate eccentrically so as to revolve along the inner peripheral surface of the stator while rotating inside the stator. It has a connecting shaft for connecting the portion and the rotor, and is characterized in that the above-mentioned connecting shaft is used as the connecting shaft.

Since the uniaxial eccentric screw pump of the present invention is used by connecting the connecting shaft of the present invention described above to the rotor and the drive side rotating portion of the uniaxial eccentric screw pump, the rotation angle of the drive side can be adjusted to the rotor without delay in response. Can be told to. Further, since the uniaxial eccentric screw pump of the present invention employs the connecting shaft of the present invention which can be shortened without deteriorating the response performance to the rotation angle on the drive side, the size can be reduced. As a result, the installation space can be reduced even with a uniaxial eccentric screw pump that uses a connecting shaft. Further, as a result, the volume of the casing of the uniaxial eccentric screw pump is reduced, and the residual amount of fluid in the casing can be reduced. Therefore, it can be suitably used in fields where particularly expensive fluid discharge is required (for example, battery manufacturing, semiconductor manufacturing, etc.).

In the uniaxial eccentric screw pump of the present invention, it is preferable that the twisting direction of the rotor and the twisting direction of the connecting shaft coincide with each other.

According to such a configuration, it becomes possible to push the fluid in the casing toward the stator side with the rotation of the connecting shaft described above. Therefore, even if the fluid has a high viscosity, the fluid in the casing can be suitably pushed toward the stator side. As a result, the volume of the internal space of the stator can be easily filled with the fluid, so that the transfer efficiency is improved. Further, when the pump is used for reverse suction, the discharge of the fluid discharged from the stator to the outside of the casing can be further assisted.

According to the present invention, it is possible to provide a connecting shaft having low bending rigidity (having flexibility) and high torsional rigidity without lengthening the length. Therefore, by adopting the connecting shaft, various devices and various devices can be provided. The mechanism can be miniaturized. Further, by adopting the connecting shaft of the present invention for the uniaxial eccentric screw pump, it is possible to provide a highly versatile and compact pump.

It is a perspective view of the connecting shaft which concerns on one Embodiment of this invention. (A) to (g) are modified examples of the cross-sectional shape of the connecting shaft of the present invention. It is a graph which shows the relationship between the total twist angle of a connecting shaft, and a reaction force. It is a graph which shows the relationship between the total twist angle of a connecting shaft, and a reaction force. It is explanatory drawing of the evaluation method of a connecting shaft. This is the evaluation result of the connecting shaft. It is explanatory drawing which compared the conventional flexible connecting shaft and the modification of the connecting shaft of this invention. It is sectional drawing of the uniaxial eccentric screw pump which concerns on one Embodiment of this invention. It is a schematic perspective view of a part of the uniaxial eccentric screw pump of this invention.

The connecting shaft 10 according to the embodiment of the present invention will be described in detail with reference to the drawings.

The connecting shaft 10 of the present invention connects the first member and the second member in various devices and mechanisms such as various pumps and compressors, and transmits the power of the power source from the first member to the second member. Used for. Among them, the connecting shaft 10 of the present invention is preferably used to transmit the eccentric motion from the first member to the second member.

As shown in FIG. 1, the connecting shaft 10 of the present invention has a twisted shape in which a plate-shaped member 11 having a rectangular cross-sectional shape 13 is twisted so as to continuously rotate in the axial direction. The part 12 is provided.

The cross-sectional shape of the cross section 13 is formed in a rectangular shape having a length in the short side direction of a and a length in the long side direction of b, and the length of the connecting shaft 10 in the axial direction is L. Here, the cross-sectional shape is formed so as to pass through the axial position regardless of the cross-sectional view at any position in the axial direction. That is, the twisted shape portion 12 is formed by twisting the plate-shaped member in the axial direction so that the axial center of the cross section 13 is located on the axial line.

Further, the cross-sectional shape has the direction in which the moment of inertia of area in the cross-section 13 is minimized as the first direction, the length in the first direction, and the second direction orthogonal to the first direction on the same cross-section. The length to is different. In the present embodiment, the first direction in which the moment of inertia of area is minimized is the short side direction, and the length in the first direction is a. In the present embodiment, the direction of the short side having a thin thickness corresponds to the first direction which is the direction in which the moment of inertia of area is minimized. Further, the second direction orthogonal to the first direction on the same cross section is the long side direction, and the length in the second direction is b. That is, the length a in the first direction (short side direction) and the length b in the second direction (long side direction) are configured to be different.

Here, the moment of inertia of area in the first direction (short side direction) is expressed by the following formula.
(Second moment of area in the first direction) = ba3 / 12

The moment of inertia of area in the second direction (long side direction) is expressed by the following formula.
(Second moment of inertia of area in the second direction) = ab3 / 12

As described above, the flexural rigidity in the direction in which the moment of inertia of area is minimized is reduced by forming the cross-sectional shape so that the length in the first direction and the length in the second direction are different. That is, in the present embodiment, the bending rigidity in the short side direction in the cross section 13 is lowered. Therefore, the flexibility increases in the short side direction in the cross section 13. Further, in the other long side direction, the thickness is thick and the bending rigidity is high. Therefore, the flexibility decreases in the long side direction. As described above, the characteristics of the moment of inertia of area change depending on the ratio of the short side a and the long side b (β = b / a).

Further, the connecting shaft 10 has a twisted shape portion 12 as described above, and is continuously twisted as the cross-sectional shape approaches the axial direction. Therefore, the first direction and the second direction are displaced in each direction while continuously drawing an arc. As a result, the direction of high flexibility with low flexural rigidity is also continuously displaced in the circumferential direction. That is, as will be described in detail later, for example, one end of the connecting shaft 10 is connected to the power source as the first member of the uniaxial eccentric screw pump 30, and the other end is connected to the rotor 60 as the second member to connect the connecting shaft. When the 10 is rotationally driven, the high flexibility direction and the low flexibility direction of the connecting shaft 10 are displaced while continuously turning in the axial direction. Therefore, the entire connecting shaft functions as a member having appropriate flexibility. The degree of flexibility of the connecting shaft 10 can be appropriately adjusted according to the material used for the connecting shaft 10.

The connecting shaft 10 is configured to be continuously twisted as described above, and the second direction (long side direction) having high bending rigidity is continuously displaced while twisting in the axial direction. As a result, the connecting shaft 10 has a direction in which the moment of inertia of area is small and the bending rigidity is low in any direction of 360 ° in the circumferential direction. Therefore, the connecting shaft 10 is originally displaced. The reaction force (restoring force) that tries to return to is also reduced. Further, when the connecting shaft 10 rotates, a part of the moment in the twisting direction applied to the twisted shape portion 12 which is twisted in the initial state is converted into an axial force by the effect of the twisting, so that it is substantially. It is presumed that the torsional rigidity of the connecting shaft 10 is increased. As a result, the connecting shaft 10 is prevented from twisting when a rotational torque is applied.

From the above, the cross-sectional shape is not limited to a rectangular shape, and various types can be adopted as long as the moment of inertia of area in the first direction and the moment of inertia of area in the second direction are different. .. For example, the cross-sectional shape may be an elliptical shape, a parallel quadrilateral shape, a rounded corner shape with rounded corners, or a rectangular shape partially chamfered, as in the modified examples of FIGS. 2A to 2G. A rhombus or the like can be adopted. In this case, as shown in the figure, the length in the first direction (short side) is represented by a, and the length in the second direction (long side) is represented by b.

Further, when the cross-sectional shape is twisted so as to swivel in a continuous or intermittent step shape toward the axial direction, the cross-sectional shape is defined from the viewpoint of ease of high-precision manufacturing. The shape is line-symmetrical with respect to the axis of symmetry 14, with the first axis passing through the torsion axis center position and along the first direction as the axis of symmetry 14, and the second axis passing through the torsion axis center position and along the second direction. It is preferable that the shape is line-symmetrical with the axis of symmetry 16 and at least one of the shapes point-symmetrical with respect to the point of symmetry 15 with the torsional axis as the point of symmetry 15. That is, the cross-sectional shape of the connecting shaft 10 is symmetrical with respect to both the

axes

14 and 16 and point-symmetric with respect to the point 15 as in the examples of FIGS. 2A, 2C, and 2F. , The shape is line-symmetric with respect to the axis of symmetry 14 as in the example of FIG. 2 (g), but the shape is asymmetric with respect to the axis of symmetry 16 and the point of symmetry 15, as shown in FIG. 2 (h). It is line-symmetric with respect to the axis of symmetry 16, but has a shape asymmetric with respect to the axis of symmetry 14 and the point of symmetry 15, and is point-symmetric with respect to the point of symmetry 15 as shown in FIGS. 2 (b) and 2 (d). However, it is preferable that the symmetry axes 14 and 16 are asymmetrical.

Next, the configuration of the twisted shape portion 12 of the connecting shaft 10 will be described in detail below.

In the embodiment shown in FIG. 1, a twisted shape portion 12 having a total twist angle of 720 ° (the number of twists is 2 turns, hereinafter also referred to simply as 2 turns) is formed on the connecting shaft 10. Here, as a result of diligent research by the present inventors, when the total twist angle is a multiple of 180 ° (0.5 turns) ± 20 °, an appropriate displacement in the bending direction is allowed and the above-mentioned reaction force It turned out that the fluctuation can be reduced. This is because if the total twist angle is a multiple of 180 °, the displacement in the bending direction and the twisting direction for one rotation (360 °) can be covered evenly in half a rotation (180 °) around the rotation axis. Is presumed to be. Therefore, since the connecting shaft 10 of the present embodiment acts while the displacement in the bending direction and the displacement in the twisting direction are evenly dispersed by 360 °, the connecting shaft 10 has appropriate flexibility and the twisting direction. It has both high rigidity. The setting of ± 20 ° will be described later.

FIGS. 3 and 4 show graphs showing the evaluation results of the change in reaction force with respect to the change in the total twist angle and the displacement direction.

For the evaluation, the same conditions other than the total twist angle (that is, the same material, cross-sectional shape, and overall length) were used, and one end of the connecting shaft 10 was fixed and the other end was displaced only in the X direction. The reaction force at that time is set to 100%, and the increase or decrease of the reaction force when the displacement direction is changed is recorded. In the graph, the displacement direction is recorded on the horizontal axis and the reaction force is recorded on the vertical axis.

As shown in FIG. 3, when the total twist angle is 405 ° (1.125 turns), 450 ° (1.25 turns), and 495 ° (1.375 turns), which are not multiples of 180 °, the total twist angle ψ is. It can be seen that the reaction force increases as compared with 360 ° (1 turn) and 540 ° (1.5 turns), which are multiples of 180 °.

Similarly, in FIG. 4, the reaction force is reduced at 720 ° (2 turns) and 900 ° (2.5 turns) where the total twist angle is a multiple of 180 °, and the total twist angle is not a multiple of 180 °. Then, it can be seen that the reaction force increases.

As described above, when the total twist angle changes stepwise from 360 ° (1 turn) to 900 ° (2.5 turns), the volatility of the reaction force increases or decreases. Further, the volatility of the reaction force is reduced every time the total twist angle is a multiple of 180 °. That is, when the total twist angle exceeds 360 ° (1 turn), the volatility of the reaction force increases, and as the total twist angle approaches 540 ° (1.5 turns), the volatility of the reaction force decreases. After that, similarly, the volatility of the reaction force decreases for each multiple of the total twist angle of 180 °, and the volatility of the reaction force increases as the distance from the multiple of 180 ° increases. The graph shows the relative value of the reaction force, and the absolute value of the reaction force tends to decrease as the total twist angle increases.

In addition, as the total twist angle increases in multiples of 180 ° such as 360 ° (1 roll), 540 ° (1.5 turns), 720 ° (2 turns), 900 ° (2.5 turns), It can be seen that the volatility of the reaction force is reduced.

As described above, the connecting shaft 10 of the present invention preferably has a total twist angle of the twisted shape portion 12 that is a multiple of 180 degrees. Considering the error in manufacturing the connecting shaft 10 and the error due to the shape of the connecting portion when connecting the first member and the second member in use, the error amount is ± 20 ° in the total twist angle. Is preferable. The total twist angle of 180 ° (0.5 turns) has the effect of reducing the reaction force in the displacement direction, which is the most bendable, but the reaction force fluctuates greatly when the displacement direction changes, so the total twist angle is large. 360 ° (1 roll) or more is preferable.

Next, the connecting shaft 10 of the present invention will be described below with an example of an embodiment compared with the conventional flexible connecting shaft 90.

FIG. 6 shows six types of connecting shafts 10 of the present invention having the same bending rigidity as the conventional flexible connecting shaft 90 under preconditions corresponding to the usage conditions of a general uniaxial eccentric screw pump. It shows the evaluation result of comparing the sword and the torsional rigidity with the conventional flexible connecting shaft 90. FIG. 7 is a diagram showing connecting shafts 10a to 10f according to a modified example of the present invention, including a comparative example, based on the table of FIG.

The evaluation method of the above evaluation will be described below with reference to FIG.

The preconditions for the flexible connecting shaft 90 of the comparative example and the connecting shaft 10 of the present invention are as follows. One end of the flexible connecting shaft 90 is fixed to form a fixed end 90a, and a displacement of 1 mm perpendicular to the axial direction is applied to the other end and a torque of 1 Nm is applied to the other end. The flexible connecting shaft 90 of the round bar (comparative example) and the flexible connecting shaft 90 of the round bar so that the reaction force at this time when the flexible connecting shaft 90 tries to return to the center is 1N and the stress due to bending and twisting (comparative stress) is 205 MPa. The dimensions of the connecting shaft 10 of the present invention are determined, and comparative evaluation is performed. Further, the flexible connecting shaft 90 of the comparative example and the connecting shaft 10 of the present invention are all made of a material having a longitudinal elastic modulus of 200 GPa and a lateral elastic modulus of 76.9 GPa.

As a comparative example, when the flexible connecting shaft 90 of a round bar was designed under the above-mentioned preconditions, the cross section was φ3.52 mm and the length was 262 mm. The flexible connecting shaft 90 in this case had a twist angle of 12.9 ° due to torque.

Further, as Example 1, under the above-mentioned preconditions, a plate having a rectangular cross section 13 (cross section dimensions: 1.6 mm × 16.0 mm, β = 10) has a total twist angle of 360 ° (1 roll). When designed as described above, a connecting shaft 10a having a length of 275 mm was obtained. The connecting shaft 10a had a twist angle of 6.55 ° due to torque. Therefore, the length of the connecting shaft 10a is + 5%, which is slightly longer than that of the comparative example, but the torsional angle due to torque is -50%, which is significantly improved as compared with the comparative example. ..

The above-mentioned connecting shaft 10 can be manufactured by, for example, twisting a plate-shaped member a required number of times or cutting a columnar member and cutting it out. The production of the connecting shaft 10 is not limited to these, and various methods can be adopted.

The connecting shafts of Examples 2 to 6 are designed as connecting shafts 10b to 10f under the conditions of each of the examples of FIG. 5 as in the case of the first embodiment. The evaluation results of each example are shown in FIG. As shown in the evaluation results, it can be seen that the flexural rigidity is significantly improved after the dimensions are significantly shortened in each of the examples as compared with the comparative example.

It should be noted that the above-described embodiment is designed for convenience in order to compare the length and the flexural rigidity under predetermined conditions for easy understanding, and the present invention is not limited thereto and is appropriately modified within the scope of the invention. it can. Further, as the material to be used, for example, a metal such as titanium and stainless steel and a resin member such as other engineering plastics can be preferably used, but the present invention is not limited to these, and various materials may be used depending on the application. Can be done.

Next, the uniaxial eccentric screw pump 30 according to the embodiment of the present invention will be described in detail with reference to FIGS. 8 and 9. In the present embodiment, the above-mentioned connecting shaft 10 is used as a connecting member between the rotor 60 (first member) of the uniaxial eccentric screw pump 30 and the power transmission mechanism 70 (second member).

The uniaxial eccentric screw pump 30 is a so-called rotary volume type pump in which the pump mechanism 31 is a main part. The uniaxial eccentric screw pump 30 has a configuration in which a stator 50, a rotor 60, a power transmission mechanism 70, and the like are housed inside a casing 40. The casing 40 is made of metal and is a tubular member, and a first opening 42 is provided on one end side in the longitudinal direction. A second opening 44 is provided on the outer peripheral portion of the casing 40. The second opening 44 communicates with the internal space of the casing 40 at the intermediate portion 46 located at the intermediate portion in the longitudinal direction of the casing 40.

The first opening 42 and the second opening 44 are portions that function as suction ports and discharge ports of the pump mechanism 31, respectively. The uniaxial eccentric screw pump 30 can function the first opening 42 as a discharge port and the second opening 44 as a suction port by rotating the rotor 60 in the forward direction. Further, by rotating the rotor 60 in the opposite direction, the first opening 42 can function as a suction port and the second opening 44 can function as a discharge port.

The stator 50 is a member having a substantially cylindrical appearance shape formed of an elastic body such as rubber or a material containing resin or the like as a main component. The inner peripheral surface 52 of the stator 50 is a member having an internal thread shape with n + 1 threads (n = 1 in this embodiment). Further, the through hole 54 of the stator 50 is formed so that the cross-sectional shape (opening shape) thereof is substantially oval when viewed in cross section at any position in the longitudinal direction of the stator 50.

The rotor 60 is a metal shaft body having an male thread shape of n threads (n = 1 in this embodiment). The rotor 60 is formed so that its cross-sectional shape is substantially a perfect circle when viewed in cross section at any position in the longitudinal direction. The rotor 60 is inserted into the through hole 54 formed in the stator 50 described above, and can freely rotate eccentrically inside the through hole 54.

When the rotor 60 is inserted through the stator 50, the outer peripheral surface 62 of the rotor 60 and the inner peripheral surface 52 of the stator 50 are in close contact with each other at the tangent line between them, and the inner peripheral surface 52 of the stator 50 and the outer peripheral surface of the rotor 60 are brought into close contact with each other. A fluid transport path 56 (cavity) is formed between the two. The fluid transport path 56 extends spirally in the longitudinal direction of the stator 50 and the rotor 60.

When the rotor 60 is rotated in the through hole 54 of the stator 50, the fluid transport 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 transport path 56 from one end side of the stator 50, and the fluid is transferred toward the other end side of the stator 50 in a state of being confined in the fluid transport path 56. , It is possible to discharge at the other end side of the stator 50. The pump mechanism 31 of the present embodiment is used by rotating the rotor 60 in the forward direction, and it is possible to pump the viscous liquid sucked from the second opening 44 and discharge it from the first opening 42. There is.

The power transmission mechanism 70 is for transmitting power from the drive machine 80 to the rotor 60 described above. The power transmission mechanism 70 has a power transmission unit 72 and an eccentric rotation unit 74. The power transmission unit 72 is provided on one end side of the casing 40 in the longitudinal direction. The power transmission unit 72 has a rotation shaft 73 that rotates under the power of the drive machine 80. The rotating shaft 73 is pivotally supported by the bearing 75 and transmits the power of the driving machine 80 to the eccentric rotating portion 74.

The eccentric rotating portion 74 is provided in the intermediate portion 46 of the casing 40. The eccentric rotation unit 74 is a portion that connects the power transmission unit 72 and the rotor 60 so that power can be transmitted. The above-mentioned connecting shaft 10 is adopted for the eccentric rotating portion 74. As a result, the eccentric rotating unit 74 can transmit the rotational power generated by operating the drive machine 80 to the rotor 60 to rotate the rotor 60 eccentrically.

The connecting shaft 10 connects the power transmission unit 72 and the rotor 60 so that the rotor 60 can rotate eccentrically while rotating along the inner peripheral surface 52 of the stator 50 while rotating inside the stator 50. The connecting shaft 10 has a characteristic of being able to suppress twisting in the direction around the axis while allowing bending in the direction intersecting the axis direction.

Further, the connecting shaft 10 has a connecting portion 76 on each of the drive side and the rotor side, and a twisted shape portion 12 is formed between the connecting portions 76. As a result, the connecting shaft 10 can transmit the rotational driving force generated by operating the driving machine 80 to the rotor 60 to eccentrically rotate the rotor 60.

As shown in FIG. 9, the connecting shaft 10 is connected to the rotor 60 and the rotating shaft 73 as the power transmission unit 72 via the connecting portion 76. The connecting portion 76 has a short cylindrical base for connecting to the rotor 60 and the rotating shaft 73. The connecting portion 76 is provided with a radius at a joint portion connecting the base and the twisted shape portion 12. By providing the radius in this way, it is possible to prevent stress from concentrating on the connecting portion 76 and prevent breakage of the connecting shaft 10 at the connecting portion 76.

The rotor 60 side and the rotating shaft 73 side of the connecting portion 76 are provided with threaded portions (not shown) on which reverse threads are formed. Further, a reverse screw-shaped screw hole (not shown) is provided at the base end portion of the rotor 60 and the tip end portion of the rotating shaft 73. The rotor 60 and the connecting shaft 10 are connected by screwing the threaded portion of the connecting portion 76 into the screw hole. Further, the rotating shaft 73 and the connecting shaft 10 are connected by screwing the threaded portion of the connecting portion 76 into the screw hole. When a radius is provided to connect the connecting shaft 10 to the rotor 60 or the rotating shaft 73, an error may occur in the total twist angle described above. Therefore, as described above, the total twist angle is preferably a multiple of 180 ° ± 20 °, which is a multiple of 180 ° and includes the above error and manufacturing error.

In the uniaxial eccentric screw pump 30 of the present invention, the connecting shaft 10 is adopted for connecting the rotating shaft 73 and the rotor 60. That is, as the connecting shaft 10, one that can suppress twisting in the direction around the axis while allowing bending in the direction intersecting the axis direction is adopted. Therefore, in the uniaxial eccentric screw pump 30, even if it is used under harsh usage conditions such as pumping a low-viscosity fluid at a low speed, the rotor 60 is placed inside the stator 50 without causing stick slip or pulsation. It can be rotated smoothly. Therefore, the uniaxial eccentric screw pump 30 of the present invention is excellent in terms of operational stability.

Further, in the uniaxial eccentric screw pump 30 of the present invention, since the connecting shaft 10 having appropriate flexibility and high torsional rigidity is adopted, when the conventional flexible connecting shaft 90 of a round bar is adopted, As such, the distance between the rotating shaft 73 and the rotor 60 does not become long. As a result, the uniaxial eccentric screw pump 30 can be made compact in the longitudinal direction. Further, since the connecting shaft 10 is connected to the rotor 60 and the rotating shaft 73 by the threaded portion of the connecting portion 76 as described above, foreign matter due to wear does not occur as compared with the universal joint. Therefore, in the uniaxial eccentric screw pump 30, the problem of foreign matter being mixed into the fluid due to wear of the connecting shaft 10 can be minimized.

Further, in the uniaxial eccentric screw pump 30 of the present invention, it is preferable that the twisting direction of the rotor 60 and the twisting direction of the connecting shaft 10 match. As a result, the fluid in the casing 40 can be pushed toward the stator 50 as the connecting shaft 10 turns. Therefore, even if the fluid has a high viscosity, the fluid in the casing 40 can be suitably pushed toward the stator 50. As a result, the volume of the internal space of the stator 50 can be easily filled with the fluid, so that the transfer efficiency is improved. Further, when the pump is used for reverse suction, the discharge of the fluid discharged from the stator 50 to the outside of the casing 40 can be further assisted.

In the uniaxial eccentric screw pump 30 described above, an example in which the rotor 60 and the rotating shaft 73 of the power transmission unit 72 are connected to the connecting shaft 10 via the connecting portion 76 has been shown, but the pump is connected by any other method. It may be. For example, a screw shaft may be provided at the end of the rotor 60 or the end of the rotating shaft 73, a screw hole may be provided on the connecting shaft 10 side, and the screw shaft may be screwed into the screw hole for connection. Further, in the present embodiment, the connecting shaft 10 is connected to the rotor 60 and the rotating shaft 73 by a screw, but the connection by pins or welding is not excluded, and various connecting means are used depending on the application. be able to.

The connecting shaft 10 of the present embodiment can be used not only as the uniaxial eccentric screw pump 30 described above, but also as an eccentric shaft of various devices. For example, it can be preferably used in fields such as pumps, compressors, and reciprocating mechanisms that utilize eccentric rotation.

Further, in the connecting shaft 10 of the present embodiment, the twisted shape portion 12 is formed in a shape in which the shape of the cross section orthogonal to the axial direction of the connecting shaft 10 is continuously twisted toward the axial direction. Therefore, a twisted shape portion having a twisted shape so as to swivel in an intermittent step shape may be formed at least in a part thereof.

The above is the embodiment of the present invention, but it goes without saying that the above-described embodiment is merely an embodiment, and the present invention is not limited to the above-described embodiment.

The present invention can be used in fields where flexural rigidity is low and high torsional rigidity is required, and can be suitably used for eccentric shafts which require flexibility and high torsional rigidity. .. Further, as a uniaxial eccentric screw pump, it can be suitably used in a field where a viscous liquid is required to be discharged.

10 Connecting shaft 11 Plate-shaped member 12 Twisted shape part 13 Cross section 14 Symmetric axis 15 Symmetry point 30 Uniaxial eccentric screw pump 31 Pump mechanism 46 Intermediate part 56 Fluid transport path 60 Rotor 73 Rotating shaft (driving side rotating part)
80 Drive 90 Flexible connecting shaft (round bar)

Claims

A connecting shaft that is flexible and connects the first member and the second member.
At least a part of the twisted shape portion in which the shape of the cross section orthogonal to the axial direction of the connecting shaft is a shape that is continuously twisted toward the axial direction or a shape that is twisted so as to swivel in an intermittent step shape. In preparation for
The moment of inertia of area on the cross section is different between the first direction orthogonal to the axial direction and the minimum moment of inertia of area in the cross section and the second direction orthogonal to the first direction on the same cross section. A connecting shaft characterized by that.
The torsional axis of the connecting shaft is within the shape of the cross section when viewed in cross section at any position in the axial direction, and the shape of the cross section passes through the torsion axis position and follows the first direction. At least one shape that is line-symmetric with respect to one axis, a shape that passes through the torsion axis position and is line-symmetric with respect to the second axis along the second direction, and a shape that is point-symmetric with respect to the torsion axis. The connecting shaft according to claim 1.
The connecting shaft according to claim 1 or 2, wherein the total twist angle in the twisted shape portion is a multiple of 180 degrees ± 20 degrees.
The drive side rotating part that rotates by the power of the drive machine,
A rotor composed of a male screw type shaft and
A stator through which the rotor can be inserted and whose inner peripheral surface is formed in a female thread shape,
It has a connecting shaft connecting the drive side rotating portion and the rotor so that the rotor can rotate eccentrically so as to revolve along the inner peripheral surface of the stator while rotating on the inside of the stator.
A uniaxial eccentric screw pump, wherein the connecting shaft according to any one of claims 1 to 3 is used as the connecting shaft.
The uniaxial eccentric screw pump according to claim 4, wherein the twisting direction of the rotor and the twisting direction of the connecting shaft coincide with each other.