TUBE PUMP
A tube pump capable that prevents and minimizes torque variation in a drive motor regardless of the rotation direction of a rotor unit includes a casing in which a liquid-flowing tube is arranged; a drive motor provided with a driving shaft rotatable in forward and reverse directions; a rotor body; roller holders supported on the rotor body to swing with respect to the rotor body; pressing rollers rotatably supported on the roller holders to press the tube against an inner circumferential wall surface of the casing; and biasing units biasing the roller holders, when swung, to be returned to a pre-swing position. The roller holders are configured to swing with respect to the rotor body in a direction opposite to a rotation direction of the rotor body.
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1. Field of the Invention
The present invention relates to a tube pump mounted to a dialysis device or the like.
2. Description of the Related Art
A tube pump that discharges a liquid existing within a liquid-flowing tube by rotating a rotor unit having pressing rollers with a drive motor and squeezing the tube with the pressing rollers is known in the art. Such a tube pump is disclosed in, e.g., Japanese Patent Application Publication No. H06-218042. In this tube pump, the rotor unit includes a rotor body engaging with a driving shaft of the drive motor, a pair of swing arms swingably pivoted to the rotor body in a symmetrical relationship with each other, pressing rollers rotatably supported on the tip end portions of the swing arms and compression springs arranged to bias the swing arms in an outwardly opening direction. The rotor body and the swing arms being made essentially of a metallic material such as aluminum die-cast or the like.
It is sometimes the case that, during retransfusion or depending on the specifications of a dialysis device, the tube pump is used by reversely rotating the rotor unit. In this case, it is desirable to ensure that the drive motor does not suffer from severe torque variation.
The swing arms of the tube pump disclosed in Japanese Patent Application Publication No. H06-218042 are configured to apply a specified pressing force to the tube by bringing the pressing rollers into contact with the tube at a predetermined angle during forward rotation of the rotor unit. Because of this arrangement, the pressing rollers cannot make contact with the tube at the same predetermined angle during reverse rotation of the rotor unit, which results in an increase in the pressing force applied to the tube by the pressing rollers. As a consequence, the reaction force (load) of the tube acting against the pressing rollers (rotors) will be increased and severe torque variation will occur in the drive motor (or the driving shaft). Accordingly, a demand has existed for a tube pump capable of suppressing torque variation in the drive motor regardless of the rotation direction of the rotor unit.
SUMMARY OF THE INVENTIONPreferred embodiments of the present invention provide a tube pump that prevents and minimizes torque variation in a drive motor regardless of the rotation direction of a rotor unit.
In accordance with a first preferred embodiment of the present invention, a tube pump preferably includes a casing including an arc-shaped inner circumferential wall surface along which a liquid-flowing tube is arranged; a drive motor provided with a driving shaft rotatable in forward and reverse directions; a rotor body arranged in a center position of the arc-shaped inner circumferential wall surface to rotate together with the driving shaft; roller holders supported on the rotor body to swing with respect to the rotor body and arranged to move toward and away from the driving shaft on a plane that is perpendicular or substantially perpendicular to the driving shaft; pressing rollers rotatably supported on the roller holders and arranged to press the tube against the inner circumferential wall surface; and biasing units interposed between the rotor body and the roller holders to bias the roller holders away from the driving shaft and to bias the roller holders, when swung, to be returned to a pre-swing position, the roller holders configured to swing with respect to the rotor body in a direction opposite to a rotation direction of the rotor body.
With such a configuration, if the rotor body is rotated by the rotation of the driving shaft, the pressing roller pressing the tube receives a reaction force (load) from the tube. The load acts on the roller holder supporting the pressing roller. If the load is equal to or greater than a predetermined value, the roller holder swings with respect to the rotor body in a direction opposite to the rotation direction of the rotor body. This prevents a large load from being applied to the rotor body through the roller holder, thereby preventing an occurrence of a large torque variation in the driving shaft. In particular, even when the rotor body is rotated in the reverse direction, it is possible to drive the drive motor with no large torque burden borne by the drive motor as compared with the forward rotation direction.
If the rotor body further rotates and if the pressing roller pressing the tube becomes detached from the tube and fails to receive the load from the tube, the roller holder that is swung with respect to the rotor body is returned to the pre-swing position by the biasing force of the biasing units. As the rotor body rotates in this manner, the tube is squeezed by the pressing rollers to discharge the liquid existing therein.
In accordance with a second preferred embodiment of the present invention, a tube pump is provided in which the rotor body includes a pair of engagement projection portions extending in an extension direction of the driving shaft, the engagement projection portions arranged in opposite side areas of the rotor body along a direction that is perpendicular or substantially perpendicular to the extension direction of the driving shaft and the biasing direction of the biasing units, the roller holders including a pair of engagement recess portions extending in the extension direction of the driving shaft and arranged to engage with the engagement projection portions to thereby provide rotation fulcrums for the roller holders.
With such a configuration, if the rotor body is rotated by the rotation of the driving shaft, the rotation of the rotor body is transferred to the roller holder engaging with the rotor body. The leading engagement projection portion of the roller holder comes into engagement with the leading engagement recess portion of the roller holder. The rotor body pulls the roller holder in the rotation direction. Thus, due to the reaction force of the tube acting on the pressing roller, a swing force acts on the roller holder about a rotation fulcrum, i.e., the leading engagement recess portion and the leading engagement projection portion engaging with each other. The roller holder is swung against the pressing force to release the load. This prevents a large load from being applied to the rotor body through the roller holder, thereby preventing the occurrence of large torque variation in the driving shaft.
If the rotor body further rotates and if the pressing roller pressing the tube becomes detached from the tube and fails to receive the load from the tube, the roller holder swung with respect to the rotor body is returned to the pre-swing position by a biasing force provided by the biasing units. By such rotation of the rotor body, the other pressing roller kept out of contact with the tube operates just like the pressing roller which has pressed the tube. As the rotor body rotates in this manner, the tube is continuously squeezed by the pressing rollers to discharge the liquid contained therein.
Since the rotor body and the roller holders are brought into engagement with each other by the engagement projection portions and the engagement recess portions to define the rotation fulcrums, the roller holders can swing with respect to the rotor body with a simplified configuration.
If the rotor body is rotated in the reverse direction the leading engagement projection portion of the roller holder (positioned opposite to the engagement projection portion mentioned above) comes into engagement with the leading engagement recess portion of the roller holder (positioned opposite to the engagement recess portion mentioned above). Thus, the roller holder swings about a rotation fulcrum, i.e., the engagement position noted above. In other words, the roller holder swings against the biasing force to release the load acting on the pressing roller. This provides a structure in which, depending on the rotation direction of the driving shaft, the rotation fulcrum of the roller holder in the rotor body is changed to a position where the load of the tube is easily released. Accordingly, even when the rotor body is rotated in the reverse direction, it is possible to drive the drive motor with no large disparity in torque burden borne by the drive motor as compared with the forward rotation.
The above and other elements, features, steps, characteristics and advantages of the preferred embodiments of the present invention will become more apparent from the following detailed description of the preferred embodiments with reference to the attached drawings.
First Preferred Embodiment
A tube pump 1 according to a first preferred embodiment of the present invention will now be described with reference to
First, the overall configuration of the tube pump 1 will be described with reference to
The casing 2 is preferably made of, e.g., a synthetic resin, and preferably includes an inner circumferential wall surface 2a, a reception void portion 7, a cover 8, guide recess portions 9 and tube clamps 10. The inner circumferential wall surface 2a preferably has an arc shape when the casing 2 is viewed in the extending direction of the driving shaft 4a (see
The tube 3 is preferably made of, for example, a transparent resin with a predetermined elasticity. The tube 3 is arranged along the inner circumferential wall surface 2a within the reception void portion 7. The driving shaft 4a of the drive motor 4 is rotatable in both the forward and reverse directions. The driving shaft 4a is arranged at the center of an arc defining the inner circumferential wall surface 2a.
The cover unit 6 preferably includes a rotor cover portion 6a connected to the rotor unit 5 and configured to cover the outer surface of the rotor unit 5 and a handle portion 6b which can be folded into the cover portion 6a and can be unfolded and gripped by a hand. The handle portion 6b is arranged to be used to manually rotate the rotor unit 5 in such an instance where the drive motor 4 is not operated due to, for example, failure or other causes. In the following description, the cover unit 6 is depicted as being detached from the rotor unit 5 for the sake of convenience in description.
Next, details of the rotor unit 5 will be described with reference to
The top plate portion 21 preferably has a substantially rectangular shape when seen in a plan view, for example, and makes up the upper portion of the rotor body 20. As shown in
As shown in
In the rotor body 20, the engagement projection portions 25 are provided in four corner positions lying on a substantially square line about the driving shaft 4a. The engagement projection portions 25 extend in the extension direction P1 of the driving shaft 4a. The engagement projection portions 25 are arranged to protrude in the direction P4 (or P5) intersecting the biasing direction P2 (or P3) of the compression coil springs 60 and the extension direction P1 of the driving shaft 4a. More specifically, each of the engagement projection portions 25 preferably includes a shaft portion 26 fixed to the rotor body 20 (the top plate portion 21 and the bottom plate portion 22) and a collar portion 27 covering the circumferential surface of the shaft portion 26. The shaft portion 26 is preferably made from, for example, a metal material to have a cylindrical columnar shape. The collar portion 27 is preferably made from, for example, a resin material to have a cylindrical shape. The collar portion 27 is preferably made of, e.g., polyacetal having superior slidability. The engagement projection portions 25 thus configured engage with the roller holders 40. The spring-receiving recess portions 28 are arranged in the connecting portion 23 to extend toward the driving shaft 4a and are configured to accommodate the compression coil springs 60.
The roller holders 40 are members arranged to rotatably support the pressing rollers 50. As shown in
As shown in
As shown in
The pressing rollers 50 are rotatably supported on the roller holders 40 to press the tube 3 against the inner circumferential wall surface 2a of the casing 2 (see
As shown in
Next, the operation of the tube pump 1 according to the first preferred embodiment will be described with reference to
One of the pressing rollers 50 biased by the compression coil springs 60, i.e., the pressing roller 50 making contact with the tube 3 (the pressing roller 50 positioned at the upper side in
In order to release the load, the roller holder 40 applied with the load swings (or is tilted) about a fulcrum, i.e., the loading one of the engagement projection portions 25 engaging with the roller holder 40. This reduces the load borne by the roller holder 40, thereby preventing the load from acting on the rotor body 20 through the roller holder 40. As a result, it is possible to prevent the load from acting on the driving shaft 4a.
If the rotor body 20 further rotates and if the pressing roller 50 pressing the tube 3 becomes detached from the tube 3 and fails to receive the load from the tube 3, the roller holder 40 swung about the engagement projection portion 25 is returned to the pre-swing position by the biasing force (restoring force) of the compression coil spring 60. By such rotation of the rotor body 20, the other pressing roller 50 kept out of contact with the tube 3 (the pressing roller 50 positioned at the lower side in
On the other hand, if the rotor body 20 is rotated clockwise as illustrated in
The tube pump 1 of the first preferred embodiment described above provides the following effects. The tube pump 1 preferably includes the roller holders 40 capable of moving toward or away from the driving shaft 4a on the plane perpendicular or substantially perpendicular to the driving shaft 4a and supported to swing with respect to the rotor body 20; the pressing rollers 50; and the compression coil springs 60 arranged to bias the roller holders 40 away from the driving shaft 4a while biasing the roller holders 40 to return back to the pre-swing position. The swing direction of the roller holders 40 with respect to the rotor body 20 is opposite to the rotation direction of the rotor body 20.
As a result of these unique features, if the pressing rollers 50 (the roller holders 40) receive an excessive reaction force (load) from the tube 3 by the rotation of the rotor body 20, the roller holders 40 can swing about the engagement projection portions 25 of the rotor body 20 to release the load. Accordingly, it is possible to prevent an excessive load from being applied to the rotor body 20 through the roller holders 40, consequently preventing torque variation in the driving shaft 4a. In particular, even when the rotor body 20 is rotated in the reverse direction, it is possible to drive the drive motor 4 without the occurrence of large torque variation, as in the case in the forward rotation.
In the tube pump 1 described above, each of the rotor body 20 and the roller holders 40 is preferably molded as a single piece by a specified engineering plastic, for example. Accordingly, as compared with aluminum die-cast molding, it is possible to omit a hole-forming process and a finishing process otherwise performed after the molding process. It is also possible to omit after-processes such as a short-blast process and a plating process. Since the engineering plastic is smaller in specific gravity than a metal material and is superior in specific strength to a typical plastic material, it is possible to realize weight reduction of a tube pump.
In the tube pump 1 described above, the rotor body 20 includes the engagement projection portions 25 protruding in the specified direction and engaging with the roller holders 40. Each of the engagement projection portions 25 includes the metal-made shaft portion 26 fixed to the rotor body 20 and the resin-made collar portion 27 covering the shaft portion 26. Each of the roller holders 40 includes the engagement recess portion 42 extending in the extension direction of the driving shaft 4a and engaging with the collar portion 27.
This enables the rotor body 20 and the roller holders 40 to engage with each other through the engagement projection portions 25 and the engagement recess portions 42. Use of the metal-made shaft portion 26 helps increase the strength of the engagement projection portions 25. Use of the resin-made collar portion 27 enables the engagement projection portions 25 to smoothly engage with the engagement recess portions 42. Thanks to this simplified configuration, the roller holders 40 can smoothly swing with respect to the rotor body 20. This makes it possible to minimize and prevent wear of the engagement projection portions 25 and the engagement recess portions 42. While the collar portion 27 of each of the engagement projection portions 25 is preferably provided by a cylindrical body slidably supported on the shaft portion 26 in the preferred embodiment described above, the present invention is not limited thereto. As an alternative example, the collar portion 27 may be provided by a (metal-made) outer race of a rolling bearing supported on the shaft portion 26.
In the tube pump 1 described above, the biasing units are preferably made up of the compression coil springs 60. The rotor body 20 is provided with the spring-receiving recess portions 28 to accommodate the compression coil springs 60. Use of the compression coil springs 60, which are general-purpose elements, makes it possible to provide the biasing units in an easy and cost-effective manner. Provision of the spring-receiving recess portions 28 makes it possible to easily secure the spaces for arrangement of the compression coil springs 60 and to shorten the length of the rotor body 20 in the biasing direction P2 (or P3).
Next, description will be made of other preferred embodiments of the present invention. With regard to other preferred embodiments, description will be centered on the points differing from the first preferred embodiment. The same components as those of the first preferred embodiment will be designated by like reference symbols but will not be described in detail. As for the points not specifically described in other preferred embodiments, the description on the first preferred embodiment is appropriately applied and/or incorporated by reference.
Second Preferred EmbodimentA tube pump 1A according to a second preferred embodiment of the present invention will be described with reference to
As shown in
Referring to
The tube pump 1A of the second preferred embodiment described above provides the same effects as those of the first preferred embodiment and additionally provides the following effects. In the tube pump 1A of the second preferred embodiment, the rotor body 20A includes the engagement projection portions 25A preferably defined by a single piece with the rotor body 20.
While each of the rotor body 20 and the roller holders 40 is preferably defined by a single piece of engineering plastic in the first and second preferred embodiments, the present invention is not limited thereto. For example, only the rotor body 20 may be defined by a single piece by an engineering plastic, for example. The rotor body 20 and the roller holders 40 or the rotor body 20 may alternatively be defined by a single piece by a resin other than an engineering plastic, as far as the resin complies with the prescribed requirements on heat resistance, strength and flexural modulus, for example.
In addition, while two pressing rollers 50 are preferably provided in the rotor unit 5 or 5A along the biasing direction P2 (or P3) in the first and second preferred embodiments, the present invention is not limited thereto. For example, three or more pressing rollers 50 may be provided in the rotor unit 5 or 5A. The number of the tube guide rollers 47 may be increased if such a need arises.
Third Preferred EmbodimentNext, a tube pump 1B according to a third preferred embodiment of the present invention will be described with reference to
The biasing unit for biasing the roller holders is defined by a leaf spring 70 (see
The tube pump 1B of the third preferred embodiment preferably includes a casing 2, a tube 3 and a rotor unit 5B arranged to squeeze the tube 3 upon rotation of a driving shaft 4a (see
The rotor body 20B is preferably made of a specified resin (e.g., an engineering plastic), for example. As shown in
As shown in
As shown in
The first bolts 73, the first backing plates 74 and the first nuts 75 are members arranged to fix the transverse plate portions 71 of the leaf spring 70 to the rotor body 20B. Each of the first backing plates 74 is preferably provided by a metal plate having a cross section of, e.g., substantially square bracket shape, and is provided with through-holes (not shown) arranged to permit insertion of the first bolts 73. The first bolts 73 are inserted into the through-holes of the first backing plates 74 and the through-holes of the rotor body 20B and are threadedly coupled with the first nuts 75.
The first nuts 75 are preferably provided by, e.g., rectangular metal plates, and are provided with female threads threadedly coupled with the first bolts 73. The first nuts 75 are accommodated within the reception groove portions 77. Use of the first bolts 73, the first backing plates 74 and the first nuts 75 makes it possible to firmly fix the transverse plate portions 71 to the rotor body 20B with the surface pressures of the first backing plates 74 and the first nuts 75.
The second bolts 78, the second backing plates 79, and the second nuts 80 are members arranged to fix the longitudinal plate portions 72 of the leaf spring 70 to the roller holders 40B as shown in
The second nuts 80 are preferably provided by, e.g., rectangular metal plates, and are provided with female threads threadedly coupled with the second bolts 78. Use of the second bolts 78, the second backing plates 79 and the second nuts 80 makes it possible to firmly fix the longitudinal plate portions 72 to the roller holders 40B with the surface pressures of the second backing plates 79 and the second nuts 80.
As can be seen in
The stopper portions 82 are defined in the rotor body 20B to extend in the extension direction P1 of the driving shaft 4a and to protrude toward the roller holders 40B. The stopper portions 82 restrict the amount of bending of the longitudinal plate portions 72 toward the rotor body 20B, thereby preventing excessive bending of the longitudinal plate portions 72 and occurrence of metal fatigue in the leaf spring 70.
Next, the operation of the tube pump 1B of the third preferred embodiment will be described with reference to
The roller holder 40B swings (gets tilted) clockwise with respect to the rotor body 20B while bending the leaf spring 70 (mainly the transverse plate portions 71) to release the load. This reduces the load applied to the roller holder 40B, thereby preventing the load from being applied to the rotor body 20B through the roller holder 40B. As a result, it is possible to prevent an occurrence of large torque variation in the driving shaft 4a.
If the rotor body 20B further rotates and if the pressing roller 50 pressing the tube 3 becomes detached from the tube 3 and fails to receive the load from the tube 3, the roller holder 40B is returned to the pre-swing position by the biasing force (restoring force) of the leaf spring 70 (mainly the transverse plate portions 71). By such rotation of the rotor body 20B, the other pressing roller 50 kept out of contact with the tube 3 (the pressing roller 50 positioned at the lower side in
On the other hand, if the rotor body 20B is rotated in the reverse direction, the same operation as stated above occurs except that the roller holders 40B swing in the direction opposite to the afore-mentioned direction (clockwise). The same actions occur as in the counterclockwise rotation. Regardless of whether the rotor body 20B is rotated in the forward direction or in the reverse direction, it is therefore possible to drive the drive motor 4 with no occurrence of large torque variation in the drive motor 4.
The tube pump 1B of the third preferred embodiment described above provides the same effects as those of the first preferred embodiment and additionally provides the following effects. The tube pump 1B of the third preferred embodiment includes the leaf spring 70 preferably having a substantially polygonal sleeve shape defined by the transverse plate portions fixed to the rotor body 20B and the longitudinal plate portions 72 fixed to the roller holders 40B. Use of the leaf spring 70 makes it possible to simplify the configuration of the biasing unit. By fixing the transverse plate portions 71 of the leaf spring 70 to the rotor body 20B, it is possible to sufficiently secure the bending amount of the leaf spring 70 and to reduce the thickness of the leaf spring 70.
Fourth Preferred EmbodimentNext, a tube pump 1C according to a fourth preferred embodiment of the present invention will be described with reference to
The tube pump 1C of the fourth preferred embodiment preferably includes a casing 2, a tube 3 and a rotor unit 5C arranged to squeeze the tube 3 upon rotation of a driving shaft 4a (see
As can be seen in
The rotor body 20C is preferably made of the resin material stated above and preferably has a substantially elliptical columnar shape. The biasing portions 90 are arranged at the opposite sides of the rotor body 20C such that the biasing direction (the expansion-contraction direction) P2 (or P3) thereof extends parallel or substantially parallel to the major axis of the rotor body 20C. The rotor body 20C is integrally fixed to the biasing portions 90 at the base sections 90a of the biasing portions 90 in the biasing direction P2.
The roller holders 40C are preferably made of the resin material described above and preferably have a substantially triangular columnar shape, for example. The roller holders 40C are integrally fixed to the biasing portions 90 at the opposite end sections 90b of the biasing portions 90 in the biasing direction P2. The biasing portions 90, the rotor body 20C and the roller holders 40C are preferably molded into a single piece, for example.
Next, the operation of the tube pump 1C of the fourth preferred embodiment will be described with reference to
The roller holder 40C swings (becomes tilted) clockwise with respect to the rotor body 20C while bending the biasing portions 90 to release the load. This reduces the load applied to the roller holder 40C, thereby preventing the load from being applied to the rotor body 20C through the roller holder 40C and the biasing portions 90. As a result, it becomes possible to prevent an occurrence of large torque variation in the driving shaft 4a.
If the rotor body 20C further rotates and if the pressing roller 50 pressing the tube 3 becomes detached from the tube 3 and fails to receive the load from the tube 3, the roller holder 40C will be returned to the pre-swing position by the biasing force (restoring force) of the biasing portions 90. By such rotation of the rotor body 20C, the other pressing roller 50 kept out of contact with the tube 3 (the pressing roller 50 positioned at the lower side in
On the other hand, if the rotor body 20C is rotated in the reverse direction, the same operation as described above occurs except that the roller holders 40C swing in the direction opposite to the afore-mentioned direction (clockwise). The same actions occur as in the counterclockwise rotation. Regardless of whether the rotor body 20C is rotated in the forward direction or in the reverse direction, it is therefore possible to drive the drive motor 4 with no occurrence of large torque variation in the drive motor 4.
The tube pump 1C of the fourth preferred embodiment described above provides the same effects as those of the first preferred embodiment and additionally provides the following effects. In the tube pump 1C of the fourth preferred embodiment, each of the biasing portions 90 is formed into a bellows shape by a resin plate having a specified predetermined elasticity and is configured to flex back and forth to allow swinging of the pressing rollers 50 in the direction perpendicular or substantially perpendicular to the biasing direction. The rotor body 20C is preferably made of a resin and is integrally fixed to the biasing portions 90 at the base sections 90a of the biasing portions 90 in the biasing direction P2. The roller holders 40C are preferably made of a resin and are integrally fixed to the biasing portions 90 at the opposite end sections 90b of the biasing portions 90 in the biasing direction P2. Accordingly, the rotor body 20C, the biasing portions 90 and the roller holders 40C can be molded into a single monolithic piece by the resin mentioned above.
While certain preferred embodiments of the present invention have been described above, the present invention is not limited to the foregoing preferred embodiments but may be modified and/or combined as desired.
For example, while each of the rotor body 20 and the roller holders 40 is preferably provided by a single piece of an engineering plastic in the first to third preferred embodiments, the present invention is not limited thereto. For example, only the rotor body 20 may be provided by a single piece of an engineering plastic. The rotor body 20 and the roller holders 40 or the rotor body 20 may be provided by a single piece of a resin other than an engineering plastic, as far as the resin complies with the prescribed requirements on, e.g., heat resistance, strength, flexural modulus, etc.
While two pressing rollers 50 are preferably provided along the biasing direction P2 in the rotor unit 5, 5A, 5B, or 5C in the first to fourth preferred embodiments, the present invention is not limited thereto. For instance, three or more pressing rollers 50 may be provided in the rotor unit 5, 5A, 5B, or 5C. The number of the tube guide rollers 47 may also be increased if necessary.
While preferred embodiments of the present invention have been described above, it is to be understood that variations and modifications will be apparent to those skilled in the art without departing from the scope and spirit of the present invention. The scope of the present invention, therefore, is to be determined solely by the following claims.
Claims
1. A tube pump, comprising:
- a casing including an arc-shaped inner circumferential wall surface along which a liquid-flowing tube is arranged;
- a drive motor provided with a driving shaft rotatable in forward and reverse directions;
- a rotor body arranged in a center position of the arc-shaped inner circumferential wall surface to rotate together with the driving shaft;
- roller holders supported on the rotor body to swing with respect to the rotor body and arranged to move both toward and away from the driving shaft on a plane that is perpendicular or substantially perpendicular to the driving shaft;
- pressing rollers rotatably supported on the roller holders to press the tube against the inner circumferential wall surface; and
- biasing units interposed between the rotor body and the roller holders to bias the roller holders away from the driving shaft and to bias the roller holders, when swung, to be returned to a pre-swing position, the roller holders being configured to swing with respect to the rotor body in a direction opposite to a rotation direction of the rotor body.
2. The tube pump of claim 1, wherein the rotor body includes engagement projection portions extending in an extension direction of the driving shaft and engaging with the roller holders, the engagement projection portions being arranged in opposite side areas of the rotor body along a direction that is perpendicular or substantially perpendicular to the extension direction of the driving shaft and the biasing direction of the biasing units, each of the engagement projection portions including a metal shaft portion fixed to the rotor body and a resin or metal collar portion rotatably supported on the shaft portion, each of the roller holders including an engagement recess portion extending in the extension direction of the driving shaft and engaging with the collar portion.
3. The tube pump of claim 1, wherein the rotor body includes engagement projection portions extending in an extension direction of the driving shaft and slidably engaging with the roller holders, the engagement projection portions arranged in opposite side areas of the rotor body along the direction that is perpendicular or substantially perpendicular to the extension direction of the driving shaft and the biasing direction of the biasing units, the roller holders including engagement recess portions extending in the extension direction of the driving shaft and slidably engaging with the engagement projection portions.
4. The tube pump of claim 1, wherein the biasing units includes a leaf spring defined by a substantial sleeve-shaped configuration including a pair of transverse plate portions extending parallel or substantially parallel to a biasing direction of the biasing units and a pair of longitudinal plate portions extending in a direction perpendicular or substantially perpendicular to the transverse plate portions to interconnect opposite end sections of the transverse plate portions, the transverse plate portions fixed to the rotor body, the longitudinal plate portions fixed to the roller holders.
5. The tube pump of claim 1, wherein the biasing units have a bellows configuration defined by resin plates having a predetermined elasticity to expand and contract in a biasing direction, the rotor body being made of the resin and integrally fixed to the biasing units at base sections of the biasing units, the roller holders being made of the resin and integrally fixed to the biasing units at end sections of the biasing units in the biasing direction.
6. A tube pump, comprising:
- a casing including an arc-shaped inner circumferential wall surface along which a liquid-flowing tube is arranged;
- a drive motor provided with a driving shaft rotatable in forward and reverse directions;
- a rotor body arranged in a center position of the arc-shaped inner circumferential wall surface to rotate together with the driving shaft;
- roller holders engaging with the rotor body to move both toward and away from the driving shaft on a plane perpendicular or substantially perpendicular to the driving shaft and swingably engaging with the rotor body;
- pressing rollers rotatably supported on the roller holders to press the tube against the inner circumferential wall surface; and
- biasing units arranged between the rotor body and the roller holders to bias the roller holders away from the driving shaft and to bias the roller holders, when swung, to be returned to a pre-swing position, the rotor body including a pair of engagement projection portions extending in an extension direction of the driving shaft, the engagement projection portions being arranged in opposite side areas of the rotor body along a direction that is perpendicular or substantially perpendicular to the extension direction of the driving shaft and the biasing direction of the biasing units, the roller holders including a pair of engagement recess portions extending in the extension direction of the driving shaft and engaging with the engagement projection portions to define rotation fulcrums of the roller holders.
7. The tube pump of claim 6, wherein the rotor body is made of resin or the rotor body and the roller holders are made of resin.
8. The tube pump of claim 6, wherein each of the engagement projection portions includes a metal shaft portion fixed to the rotor body and a resin collar portion covering the shaft portion.
9. The tube pump of claim 6, wherein the engagement projection portions are defined by a single monolithic piece with the rotor body.
10. The tube pump of claim 6, wherein the biasing units include compression coil springs, the rotor body including spring-receiving recess portions recessed toward the driving shaft and arranged to accommodate the compression coil springs.
Type: Application
Filed: Oct 21, 2011
Publication Date: Apr 26, 2012
Applicant: NIDEC SERVO CORPORATION (Kiryu-shi)
Inventors: Akira HANAZUKA (Gumma), Yoshihisa KAGAWA (Gumma)
Application Number: 13/278,407
International Classification: F04B 43/12 (20060101);