Curved flexible impeller

Abstract

An impeller is attached to a rotary shaft provided in an inner space of a housing and includes a tube fixed to the rotary shaft and a plurality of blades protruding toward an outer diameter direction from the tube. A tip of each blade is in slidable contact with an inner peripheral surface of the housing. Each blade has a shape curved toward a rotation-direction rear side of the rotary shaft in a free state and includes an extension surface on a rotation-direction front side of the rotary shaft and a compression surface on the rotation-direction rear side of the rotary shaft. A curvature radius of a root on the compression surface in the blade is formed larger than a curvature radius of a root on the extension surface in the blade.

Claims

1. An impeller attached to a rotary shaft provided in an inner space of a housing, the impeller comprising: a tube fixed to the rotary shaft; and a blade protruding toward an outer diameter direction from the tube, a tip of the blade being in slidable contact with an inner peripheral surface of the housing, wherein the blade has a shape curved toward a rotation-direction rear side of the rotary shaft in a free state and includes an extension surface on a rotation-direction front side of the rotary shaft and a compression surface on the rotation-direction rear side of the rotary shaft, and wherein a curvature radius of a root on the compression surface in the blade is formed larger than a curvature radius of a root on the extension surface in the blade.

2. The impeller according to claim 1, wherein the blade has a radial length of 9 to 15 mm, wherein a relationship of R.sub.11=0.1W.sub.1 to 0.5W.sub.1 is satisfied with Wu representing the radial length of the blade and R.sub.11 representing the curvature radius of a root on the extension surface in the blade, wherein a relationship of R.sub.13=0.5W.sub.1 to 1.0W.sub.1 is satisfied with Wu representing the radial length of the blade and R.sub.13 representing a curvature radius of a radial midsection on the compression surface in the blade, wherein a relationship of R.sub.14=2W.sub.1 to 6W.sub.1 is satisfied with Wu representing the radial length of the blade and R.sub.14 representing a curvature radius of a radial midsection on the extension surface in the blade, wherein an inclination angle .sub.1 of the extension surface near the tip of the blade with respect to an impeller diameter line is set to 4 to 9 degrees, and wherein an inclination angle .sub.2 of the compression surface near the tip of the blade with respect to the impeller diameter line is set to 5 to 10 degrees.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 is a cross-sectional view illustrating a free-state shape of an impeller according to a first embodiment of the present invention.

(2) FIG. 2 is an enlarged view of a main part illustrating a blade of the impeller according to the first embodiment of the present invention.

(3) FIG. 3 is a cross-sectional view illustrating the mounting-state shape of the impeller according to the first embodiment of the present invention.

(4) FIG. 4 is a front view of a tube provided in an impeller according to a second embodiment of the present invention.

(5) FIG. 5 is a cross-sectional view of a specific blade provided in the impeller according to the second embodiment of the present invention.

(6) FIG. 6 is a plan view illustrating a free-state shape of an impeller according to a first prior art.

(7) FIG. 7A is an enlarged view of a main part illustrating a blade of the impeller according to the first prior art.

(8) FIG. 7B is a cross-sectional view illustrating a state where the blade of the impeller according to the first prior art is wrinkled.

(9) FIG. 8A is an enlarged view of a main part illustrating a blade of an impeller according to a second prior art.

(10) FIG. 8B is a cross-sectional view illustrating a state where the blade of the impeller according to the second prior art is wrinkled.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

(11) Next, an impeller 10 according to embodiments will be described in detail with reference to accompanying drawings.

First Embodiment

(12) The impeller 10 according to the present embodiment is used for a pump device or the like. As illustrated in FIGS. 1 to 3, the impeller 10 is provided with an annular tube 20 fixed to a rotary shaft 50 provided in a shaft hole 42 of a housing 40 and a plurality of blades 30 protruding toward an outer diameter direction from the tube 20.

(13) The tube 20 is made of a resin material. The tube 20 is provided with an insertion hole 21 through which the rotary shaft 50 is inserted and a notch portion 22 provided at a part on the circumference of the insertion hole 21 and fixing the rotary shaft 50.

(14) The blade 30 is made of a rubber material such as chloroprene rubber having a hardness of Hs 50 to 70. As illustrated in FIGS. 1 to 3, the blades 30 circumferentially equally protrude from the tube 20 toward the outer diameter direction, a tip 31 is in slidable contact with an inner peripheral surface 41 of the housing 40, and the blade 30 has a shape curved to a rotation-direction rear side B of the rotary shaft 50 in a free state. An extension surface 32 and a compression surface 33 are provided in the root of the blade 30. The extension surface 32 is positioned on a rotation-direction front side A of the rotary shaft 50 and has a circular arc shape in cross section. The compression surface 33 is positioned on the rotation-direction rear side B of the rotary shaft 50 and has a circular arc shape in cross section as in the case of the extension surface 32. A curvature radius R.sub.2 of a root 35 on the compression surface 33 is set larger than a curvature radius R.sub.1 of a root 34 on the extension surface 32. In other words, the curvature radius R.sub.2 of the compression surface 33 is set larger than the curvature radius R.sub.1 of the extension surface 32.

(15) It is preferable that the impeller 10 in the present embodiment illustrated in FIG. 1 is manufactured with the following dimensions. The impeller of the present invention is not limited to the following dimensional ranges.

(16) A radial length W of the blade 30 is set to 20 to 30 mm. Accordingly, the impeller 10 according to the embodiment is a large impeller in which the radial length W of the blade 30 is large.

(17) It is preferable to set R.sub.1 to 0.1W to 0.4W with W representing the radial length of the blade 30 and R.sub.1 representing the curvature radius of the root 34 on the extension surface 32 in the blade 30. When W is 20 to 30 mm, R.sub.1 is preferably 2.5 to 10 mm and more preferably 3 to 6 mm.

(18) It is preferable to set R.sub.2 to 0.5W to 1.2W with W representing the radial length of the blade 30 and R.sub.2 representing the curvature radius of the root 35 on the compression surface 33 in the blade 30. When W is 20 to 30 mm, R.sub.2 is preferably 12 to 30 mm and more preferably 18 to 2

(19) It is preferable to set R.sub.3 to 0.8W to 1.8W with W representing the radial length of the blade 30 and R.sub.3 representing the curvature radius of a radial midsection C on the compression surface 33 in the blade 30. When W is 20 to 30 mm, R.sub.3 is preferably 20 to 45 mm and more preferably 28 to 32 mm.

(20) It is preferable to set R.sub.4 to 1W to 5W with W representing the radial length of the blade 30 and R.sub.4 representing the curvature radius of the radial midsection C on the extension surface 32 in the blade 30. When W is 20 to 30 mm, R.sub.4 is preferably 25 to 125 mm and more preferably 75 to 85 mm.

(21) As for the extension surface 32 near the tip 31 of the blade 30, it is preferable to set an inclination angle .sub.1 with respect to the diameter line of the impeller 10 to 3 to 9 degrees. More preferably, the inclination angle .sub.1 is set to 6 to 8 degrees.

(22) As for the compression surface 33 near the tip 31 of the blade 30, it is preferable to set an inclination angle .sub.2 with respect to the diameter line of the impeller 10 to 1 to 5 degrees. More preferably, the inclination angle .sub.2 is set to 1.5 to 3.5 degrees.

(23) The impeller 10 configured as described above is attached to the rotary shaft 50 eccentric to the inner peripheral surface 41 of the housing 40. By the rotary shaft 50 rotating to the rotation-direction front side A, the blade 30 slides with the inner peripheral surface 41 of the housing 40 and the blades 30 are sequentially bent toward the rotation-direction rear side B. By the blades 30 being bent, the space between a blade 30a and an adjacent blade 30b decreases. As a result, the pressure of the liquid in the space increases and the liquid is discharged to a discharge port (not illustrated). Further, once the space between the blade 30a and the adjacent blade 30b increases by the blade 30 exerting an elastic restoring force, the pressure of the liquid in the space decreases and the liquid is suctioned into a suction port (not illustrated).

(24) As described above, in the impeller 10 according to the present embodiment, a volume change is repeated in the space between the blade 30a and the adjacent blade 30b as the rotary shaft 50 rotates. Accordingly, the liquid can be sequentially introduced from the right side to the left side in FIG. 3.

(25) As illustrated in FIG. 2, in the impeller 10 according to the present embodiment, the blade 30 has a shape curved to the rotation-direction rear side B. Accordingly, the entire blade 30 smoothly bends as compared with the blade 530 according to the prior art, which is illustrated in FIGS. 7A and 8B and has a linear shape in the free state. As a result, it is possible to improve the durability of the impeller 10 by suppressing lopsided strain concentration and preventing the blade 30 from wrinkling.

(26) In the impeller 10 according to the present embodiment, the curvature radius R.sub.2 of the root 35 on the compression surface 33 in the blade 30 is set larger than the curvature radius R.sub.1 of the root 34 on the extension surface 32. Accordingly, the blade 30 is incapable of bending to the rotation-direction rear side B beyond a required range. As a result, it is possible to ensure a certain repulsive force with respect to the housing 40 of the blade 30.

(27) In the impeller 10 according to the present embodiment, the extension surface 32 and the compression surface 33 near the tip 31 of the blade 30 are inclined with respect to the diameter line of the impeller 10, and thus wrinkling can be further prevented.

(28) In the impeller 10 according to the present embodiment, the blade 30 is curved in the free state, and thus the blade 30 can be easily assembled to the rotary shaft 50 provided in the housing 40.

(29) The impeller 10 according to the present embodiment achieves the above-described action and effect simply by means of a change in the shape of the blade 30. Accordingly, the impeller 10 can be manufactured at the same cost as the impeller 510 according to the prior art.

(30) In the impeller of the present invention, strain reduction is achieved and wrinkling of the blade becomes less likely by the wall thickness of the blade being reduced.

Second Embodiment

(31) As illustrated in FIG. 4, in the impeller 10 according to the first embodiment, the tube 20 may be a bush 20A made of, for example, a resinous or metallic rigid material. A key groove 20Aa for rotation stopping with respect to the rotary shaft 50 may be provided in one place on the circumference of the inner peripheral surface of the rigid material-based bush 20A. At the position that circumferentially corresponds to the key groove 20Aa, a raised portion 20Ab as a circumferential part may be provided on the outer peripheral surface of the position so that the part where the key groove 20Aa is provided is reinforced. In this case, all of the outer diameter dimensions of the plurality of blades 30 equally distributed on the outer peripheral side of the bush 20A are constant, and thus only a specific blade 30A at the position that circumferentially corresponds to the key groove 20Aa and the raised portion 20Ab is formed so as to have a blade length shorter than the blade length of the other blades 30.

(32) As for the specific blade 30A, the rubber volume of the root 35 on the compression surface 33 becomes too large once the curvature radius of the root 35 on the compression surface 33 in the specific blade 30A is formed larger than the curvature radius of the root 34 on the extension surface 32 in the specific blade 30A as in the first embodiment described above. Then, the boundary position between the root 35 on the compression surface 33 and a length-direction middle portion (radial midsection) 36 in the specific blade 30A becomes a strain concentration portion and wrinkling may occur in the strain concentration portion. Even without the raised portion 20Ab being provided, the same can be said also in the case of a small impeller in which the radial length of each blade 30 is as small as approximately 9 to 15 mm.

(33) In this regard, the following shape is preferably adopted in a case where the length of the specific blade 30A or the blade 30 is small.

(34) In other words, preferable is manufacturing with the dimensions illustrated in an enlarged manner in FIG. 5. The impeller of the present invention is not limited to the following dimensional ranges.

(35) A radial length W.sub.1 of the specific blade 30A or the blade 30 is set to 9 to 15 mm as described above.

(36) It is preferable to set R.sub.11 to 0.1W.sub.1 to 0.5W.sub.1 with W.sub.1 representing the radial length of the specific blade 30A or the blade 30 and R.sub.11 representing the curvature radius of the root 34 on the extension surface 32 in the specific blade 30A or the blade 30. When W.sub.1 is 9 to 15 mm, R.sub.11 is preferably 1 to 5 mm.

(37) It is preferable to set R.sub.12 to 0.1W.sub.1 to 0.5W.sub.1 with W.sub.1 representing the radial length of the specific blade 30A or the blade 30 and R.sub.12 representing the curvature radius of the root 35 on the compression surface 33 in the specific blade 30A or the blade 30. When W.sub.1 is 9 to 15 mm, R.sub.12 is preferably 1 to 5 mm.

(38) It is preferable to set R.sub.13 to 0.5W.sub.1 to 1.0W.sub.1 with W.sub.1 representing the radial length of the specific blade 30A or the blade 30 and R.sub.13 representing the curvature radius of the radial midsection on the compression surface 33 in the specific blade 30A or the blade 30. When W.sub.1 is 9 to 15 mm, R.sub.13 is preferably 5 to 10 mm.

(39) It is preferable to set R.sub.14 to 2W.sub.1 to 6W.sub.1 with W.sub.1 representing the radial length of the specific blade 30A or the blade 30 and R.sub.14 representing the curvature radius of the radial midsection on the extension surface 32 in the specific blade 30A or the blade 30. When W.sub.1 is 9 to 15 mm, R.sub.14 is preferably 20 to 60 mm.

(40) As for the extension surface 32 near the tip 31 of the blade 30 or the specific blade 30A, it is preferable to set the inclination angle .sub.1 with respect to the diameter line of the impeller 10 to 4 to 9 degrees. More preferably, the inclination angle .sub.1 is set to 5 to 8 degrees.

(41) As for the compression surface 33 near the tip 31 of the blade 30 or the specific blade 30A, it is preferable to set the inclination angle .sub.2 with respect to the diameter line of the impeller 10 to 5 to 10 degrees. More preferably, the inclination angle .sub.2 is set to 7 to 10 degrees.

(42) By each curvature dimension and inclination angle being set as described above, the strain concentration portion is disposed in the R of the length-direction middle portion 36 on the compression surface 33, the R joint in the strain concentration portion disappears, the rubber volume of the root 35 on the compression surface 33 decreases, and thus wrinkling becomes unlikely.

(43) Accordingly, even in a case where the length of the specific blade 30A or the blade 30 is small, wrinkling attributable to strain concentration can be prevented as in the other blades 30 and it is possible to ensure a repulsive force with respect to the housing 40 of the specific blade 30A or the blade 30.

(44) A plurality of the raised portions 20Ab may be provided on the circumference. The raised portion 20Ab may be provided at a position not corresponding to the key groove 20Aa.