Dental handpiece

Abstract

Provided is an impeller-type dental handpiece with which both rotation efficiency of the impeller and cutting efficiency can be improved. In the impeller-type dental handpiece, the deviation in the orientation of an air supply communication hole O1, which is a communication hole of an air supply passage 121 to an internal space of a housing 11, and the deviation in the orientation of an exhaust communication hole O2, which is a communication hole of an exhaust passage 122 to the internal space of the housing 11, are both included within the range of 35-155º with respect to the central axis of the housing 11.

Description

Dental handpiece

[0001] The present invention relates to an impeller-type dental handpiece.

[0002] The inventors have proposed a dental handpiece including a housing having an impeller for rotating a cutting tool for teeth, and a handle-side housing attached to the housing and having an air supply passage for the impeller built therein (see Patent Document 1).

[0003] Japanese Patent Application Laid-Open No. 2023-162078

[0004] However, according to the conventional dental handpiece, there is room for improvement in the rotation efficiency of the impeller.

[0005] Therefore, an object of the present invention is to provide an impeller-type dental handpiece capable of improving the rotation efficiency of the impeller and thus the cutting efficiency.

[0006] The dental handpiece of the present invention includes a housing, an impeller rotatably disposed around an axis in the internal space of the housing for rotating a cutting tool for teeth, and a handle-side housing attached to the housing and provided with an air supply passage and an exhaust passage for the impeller, and the deviation in each orientation between an air supply communication hole, which is a communication hole of the air supply passage with respect to the internal space of the housing, and an exhaust communication hole, which is a communication hole of the exhaust passage with respect to the internal space of the housing, based on the central axis of the housing, is included in the range of 35° to 155°.

[0007] Configuration explanatory diagram of a dental handpiece as an embodiment of the present invention. Schematic plan view of the impeller of the dental handpiece. Configuration explanatory diagram of a main part of the dental handpiece as the first embodiment of the present invention. Configuration explanatory diagram of a main part of the dental handpiece as the second embodiment of the present invention. Configuration explanatory diagram of a main part of the dental handpiece as the third embodiment of the present invention.

[0008] (Configuration) The impeller-type dental handpiece 1, as one embodiment of the present invention shown in Figure 1, comprises a housing 11 having a substantially cylindrical internal space, an impeller 2 positioned in the internal space (turbine chamber) of the housing 11 for rotating a cutting tool 4 for cutting teeth, and a handle-side housing 12 attached to the housing 11, which is provided with an air supply passage 121 and an exhaust passage 122 for the impeller 2. A three-dimensional Cartesian coordinate system (x, y, z) is used to understand the arrangement of the components of the handpiece 1. The handle-side housing 12 is designed to have an appropriate external shape and size from the viewpoint of being grasped by a practitioner such as a dentist. As shown in Figure 1, an air supply conduit 101 is connected to the air supply passage 121, and an exhaust conduit 102 is connected to the exhaust passage 122.

[0009] As shown in Figure 1, the height position (position in the z direction) of the communication hole (supply air communication hole O1) of the supply air passage 121 relative to the internal space (turbine chamber) of the housing 11 is higher than the height position of the communication hole (exhaust communication hole O2) of the exhaust passage 122 relative to the internal space of the housing 11. The height positions of the two communication holes may be the same, or their relative positions may be reversed. The shapes of the supply air communication hole O1 and the exhaust communication hole O2 (the cross-sectional shapes of the supply air passage 121 and the exhaust passage 122) may be approximately circular, or they may be approximately elliptical, approximately rectangular, approximately trapezoidal, or approximately hexagonal, among other shapes.

[0010] As shown in Figure 1, the handle-side housing 12 is provided with an air intake passage 121 and an exhaust passage 122 for the impeller 2, as well as a water supply passage 124 that communicates with the external space of the handle-side housing 12 and opens downward toward the housing 11. As shown in Figure 3, a water supply conduit 104 is connected to the water supply passage 124, and the exhaust passage 122 is provided to merge with the water supply passage 124. The water supply passage 124 may be omitted.

[0011] The upper part of the housing 11 may be made up of a lid member, and by opening or removing the lid member, access to the internal space of the housing 11 may be made, and the impeller 2 may be replaced.

[0012] As shown in Figure 2, the impeller 2 comprises a rotor 220 fixed to or detachably attached to a substantially cylindrical shaft 20, and P blades 222 (P=12 in this embodiment) extending radially from the rotor 220. As shown in Figure 2, each blade 222 is formed in a substantially isosceles triangular prism shape extending in the direction of the rotation axis (z direction) of the impeller 2.

[0013] As shown in Figure 1, the shaft 20 is rotatably held relative to the housing 11 via upper ball bearings 111 and 112 at the upper shaft 201 and lower shaft 202, respectively. A cutting tool 4 is fixed to the lower shaft 202 coaxially with the shaft 20. The cutting tool 4 may be detachably attached to the lower shaft 202 by fitting its upper part into a hole at the bottom of the lower shaft 202. As shown in Figure 1, at least a portion of the cutting tool 4 including the file portion 40 protrudes downward from the housing 11 through a through hole 114 provided in the lower part of the housing 11.

[0014] The number of blades 222 constituting the impeller 2 may be 12, or any number such as 4, 6, 8, 10, 14, 16, 18, 24, etc. The shape of each blade 222 may be varied. For example, each blade 222 may be formed in a substantially rectangular columnar shape, a substantially elliptical columnar shape, or a substantially arc-shaped columnar shape (a columnar shape that protrudes radially so as to bend in the circumferential direction) with the rotation axis direction of the impeller 2 as its axis. Each blade 222 may also be formed in a substantially wing shape that extends radially at an inclination with respect to the rotation axis direction of the impeller 2.

[0015] The impeller 2 may be made of a light metal such as aluminum (specific gravity 2.7) or duralumin (specific gravity 2.8) or various aluminum alloys (specific gravity 2.6 to 2.8). The blade 22 may be made of ceramics such as forsterite (2MgO・SiO2) (specific gravity 3.0), silicon carbide (SiC) (specific gravity 3.16), silicon nitride (Si3P4) (specific gravity 3.3), aluminum nitride (AlP) (specific gravity 3.4), alumina (Al2O3) (specific gravity 3.8), yttria (Y2O3) (specific gravity 4.9), or zirconia (ZrO2) (specific gravity 6.0), as well as metal composite materials such as cermet (TiC・TiP) (specific gravity 6.0). The impeller 2 may be made of a heavy metal such as iron (specific gravity 7.9), nickel (specific gravity 8.8), or copper (specific gravity 8.9), or alloys thereof. If the impeller 2 is made of chromium or lead, it is preferable that the entire impeller be plated with a harmless metal such as silver or nickel. Impellers 2 with complex shapes can be manufactured by a 3D printer using raw material powder and / or by laser processing of the raw materials.

[0016] (First Embodiment) Figure 3 shows a first embodiment of the arrangement of the air supply passage 121 and the exhaust passage 122 in relation to the internal space of the housing 11. The internal space of the housing 11 is a substantially cylindrical space with the rotation axis of the impeller 2 as the central axis (parallel to the z-axis). The azimuth angle is defined with respect to the central axis of the internal space of the housing 11, with respect to a reference axis C that extends in the +x direction (longitudinal direction of the handle-side housing 12) from the central axis of the internal space of the housing 11.

[0017] As shown in Figure 3, the communication hole (air supply communication hole O1) of the air supply passage 121 is positioned at a first azimuth angle θ1 in a clockwise direction with respect to the reference axis C, as viewed from the central axis of the internal space of the housing 11, and its azimuth angle range is from θ1 - Δθ1 to θ1 + Δθ1. The first azimuth angle θ1 is, for example, included in the range of 15° to 30°. "Δθ1" is, for example, 2° to 2.5°. The angle φ1 that the direction of air supply from the air supply passage 121 to the internal space of the housing 11 (the direction of extension of the air supply passage 121 near the air supply communication hole O1) makes with the tangential direction of the internal space is, for example, included in the range of 0° to 60° or 15° to 60°.

[0018] The communication hole (exhaust communication hole O2) of the exhaust passage 122 is positioned at a second azimuth angle θ2 in a counterclockwise direction with respect to the reference axis C, as viewed from the central axis of the internal space of the housing 11, and its azimuth angle range is from θ2 - Δθ2 to θ2 + Δθ2. The second azimuth angle θ2 is greater than the first azimuth angle θ1 and is included in the range of, for example, 20° to 90°, preferably 20° to 55°. "Δθ2" is, for example, 1° to 2.5°. The angle φ2 that the exhaust direction from the internal space of the housing 11 to the exhaust passage 122 (the direction in which the exhaust passage 122 extends near the exhaust communication hole O2) makes with the tangential direction of the internal space is included in the range of, for example, 0° to 60° or 15° to 60°.

[0019] The air intake port O1 and the exhaust port O2 are located in two directions separated by an azimuth deviation θ1 + θ2 (for example, 35° to 120°) from the central axis of the internal space of the housing 11. Δθ1 (or the area of ​​the air intake port O1) and Δθ2 (or the area of ​​the exhaust port O2) may be the same, or one may be larger than the other.

[0020] (Effects) With the dental handpiece 1 of this configuration, compressed air is supplied from the compressor to the internal space of the housing 11 via the air supply conduit 101 and the air supply passage 121 by the operator's operation. In the air supply circuit that communicates with the compressor, the amount of compressed air supplied is adjusted by an air supply volume adjustment mechanism, which is configured by a pedal on the chair unit or the like. Inside the housing 11, the impeller 2 is rotated by the compressed air, and treatment such as cutting the patient's teeth is performed by a cutting tool 4 that is coaxially attached to the shaft 20 of the impeller 2. Compressed air is discharged from the internal space of the housing 11 to the outside of the dental handpiece 1 via the exhaust passage 122 and the exhaust conduit 102.

[0021] According to the inventors' findings, when the intake port O1 and exhaust port O2 are located in two directions where the azimuth angle deviation θ1 + θ2 is less than 35° from the central axis of the internal space of the housing 11, the fluid resistance of the exhaust from the internal space of the housing 11 to the exhaust passage 122 tends to increase. This is presumed to be due to the interference between the airflow from the intake passage 121 toward the internal space of the housing 11 and the airflow from the internal space of the housing 11 toward the exhaust passage 122, which generates a vortex near the exhaust port O2.

[0022] In view of the above findings, in this embodiment, the air supply port O1 and the exhaust port O2 are each positioned in two directions that are separated by an angle between 35° and 120°, with respect to the central axis of the internal space of the housing 11, where the azimuth angle deviation θ1 + θ2 is 35° or more. As a result, the aforementioned airflow interference is suppressed, which in turn improves the exhaust efficiency from the internal space of the housing 11 to the exhaust passage 122, and consequently improves the rotational efficiency of the impeller 2 and the cutting efficiency of the cutting tool 4. Furthermore, the noise generated by the high-speed rotation of the impeller 2 using compressed air is also reduced.

[0023] (Second Embodiment) Figure 4 shows the first embodiment of the arrangement of the air supply passage 121 and the exhaust passage 122 in relation to the internal space of the housing 11. The second azimuth angle θ2 is greater than the first azimuth angle θ1 and is, for example, in the range of 90° to 125°. The other configurations are substantially the same as those of the dental handpiece 1 of the first embodiment, so the same reference numerals are used for these similar components and detailed descriptions are omitted.

[0024] (Effects) In view of the above findings, in this embodiment, the air supply port O1 and the exhaust port O2 are each positioned in two directions that are separated by 105° to 155°, with respect to the central axis of the internal space of the housing 11, where the azimuth angle deviation θ1 + θ2 is 35° or more. As a result, the airflow interference described above is suppressed, which in turn improves the exhaust efficiency from the internal space of the housing 11 to the exhaust passage 122, and consequently improves the rotational efficiency of the impeller 2 and the cutting efficiency of the cutting tool 4. Furthermore, the noise generated by the high-speed rotation of the impeller 2 using compressed air is also reduced.

[0025] (Third Embodiment) Figure 5 shows a third embodiment of the arrangement of the air supply passage 121 and the exhaust passage 122 within the internal space of the housing 11. The impeller 2 is eccentrically positioned within the internal space of the housing 11 such that the spacing of the exhaust communication holes O2 relative to the rotation region of the blade 222 is wider than the spacing of the air supply communication holes O1 relative to the rotation region of the blade 222. The other configurations are substantially the same as those of the dental handpiece 1 of the first embodiment, so the same reference numerals are used for these similar components, and detailed descriptions are omitted.

[0026] (Effects) In view of the above findings, in this embodiment, the air supply port O1 and the exhaust port O2 are each positioned in two directions where the azimuth angle deviation θ1 + θ2 is 35° or more apart when viewed from the central axis of the internal space of the housing 11. Furthermore, the spacing of the exhaust port O2 relative to the rotation region of the blade 222 is wider than the spacing of the air supply port O1 relative to the rotation region of the blade 222. As a result, the airflow interference described above is further suppressed, which in turn improves the exhaust efficiency from the internal space of the housing 11 to the exhaust passage 122, and consequently improves the rotation efficiency of the impeller 2 and the cutting efficiency of the cutting tool 4. Furthermore, the noise generated by the high-speed rotation of the impeller 2 using compressed air is also reduced.

[0027] (Modification) In the third embodiment, the impeller 2 is eccentrically positioned within the internal space of the housing 11, so that the spacing of the exhaust communication holes O2 relative to the rotation region of the blade 222 is wider than the spacing of the intake communication holes O1 relative to the rotation region of the blade 222. Alternatively, or in addition to this, the shape or thickness of the housing 11 may be locally adjusted so that the inner surface of the housing 11 is locally recessed radially outward near the exhaust communication holes O2, so that the spacing of the exhaust communication holes O2 relative to the rotation region of the blade 222 is wider than the spacing of the intake communication holes O1 relative to the rotation region of the blade 222.

[0028] (Other Embodiments) In the above embodiment, the second azimuth angle θ2 was designed to be larger than the first azimuth angle θ1. However, in other embodiments, the second azimuth angle θ2 may be designed to be less than or equal to the first azimuth angle θ1. In this case, for example, the first azimuth angle θ1 may be in the range of 30° to 50°, and the second azimuth angle θ2 may be in the range of 0° to 105°.

[0029] In the above embodiment, the first azimuth angle θ1 was in the range of 15° to 30°, but in other embodiments, the first azimuth angle θ1 may be in the range of less than 15° (for example, the range of 5° to 10°).

[0030] The dental handpiece of the present invention improves the rotational efficiency of the impeller 2 and the cutting efficiency of the cutting tool 4, thereby contributing to the development of the industry by reducing stress for both dentists and patients.

[0031] 1. Dental handpiece 101. Air intake conduit 102. Exhaust conduit 104. Water supply conduit 11. Housing 111. Upper ball bearing 112. Lower ball bearing 114. Through hole 12. Handle side housing 121. Air intake passage 122. Exhaust passage 124. Water supply passage 2. Impeller 20. Shaft 201. Upper part of shaft 202. Lower part of shaft 21. First impeller 21-q. Blade 211. First blade section 212. Second blade section 214. Bridge section 22. Second impeller 22-1 to 22-12. Blade 4. Cutting tool 40. File section.

Claims

1. A dental handpiece comprising: a housing; an impeller rotatably disposed about an axis within the internal space of the housing for rotating a cutting tool for teeth; and a handle-side housing attached to the housing and provided with an air intake passage and an exhaust passage for the impeller, wherein the deviation of the orientation of the air intake communication hole, which is a communication hole for the air intake passage with respect to the internal space of the housing, and the exhaust communication hole, which is a communication hole for the exhaust passage with respect to the internal space of the housing, with respect to the central axis of the housing, is within the range of 35° to 155°.

2. A dental handpiece according to claim 1, wherein, with reference to a reference axis that extends perpendicularly to the central axis along the longitudinal direction of the handle-side housing when viewed from the central axis of the internal space of the housing, the air supply port is provided in a direction at a first azimuth angle in a clockwise direction, and the exhaust port is provided in a direction at a second azimuth angle greater than the first azimuth angle in a counterclockwise direction.

3. A dental handpiece according to claim 2, wherein the first azimuth angle is included in the range of 15° to 30°, and the second azimuth angle is included in the range of 20° to 125°.

4. A dental handpiece according to claim 3, wherein the first azimuth angle is included in the range of 15° to 30°, and the second azimuth angle is included in the range of 20° to 55°.

5. A dental handpiece according to claim 1, wherein, in a plan view with the central axis of the internal space of the housing perpendicular to the central axis, the angle between the extending direction of the respective air supply port and exhaust port and the tangential direction of the internal space or inner surface of the housing is within the range of 0° to 60°.

6. A dental handpiece according to claim 1, wherein the distance of the exhaust communication hole to the rotation region of the impeller is greater than the distance of the intake communication hole to the rotation region of the impeller.

7. A dental handpiece according to claim 6, wherein the impeller is eccentrically arranged in the internal space of the housing, so that the distance of the exhaust communication hole to the rotation region of the impeller is greater than the distance of the intake communication hole to the rotation region of the impeller.

8. A dental handpiece according to claim 6 or 7, wherein the inner surface of the housing is locally recessed at the exhaust communication hole, so that the distance of the exhaust communication hole to the rotation region of the impeller is greater than the distance of the intake communication hole to the rotation region of the impeller.

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