Dental handpiece

Abstract

To provide an impeller-type dental handpiece that can improve the rotational efficiency of the impeller, and consequently, the cutting efficiency. [Solution] The deviation of the orientation of the air supply communication hole O1, which is a communication hole for the air supply passage 121 to the internal space of the housing 11, and the exhaust communication hole O2, which is a communication hole for the exhaust passage 122 to the internal space of the housing 11, relative to the central axis of the housing 11, is within the range of 35° to 155°.

Description

Technical Field

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

Background Art

[0002] The present 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 therein (see Patent Document 1).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[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.

Means for Solving the Problems

[0006] The dental handpiece of the present invention includes a housing, an impeller rotatably disposed about an axis in the internal space of the housing for rotating a cutting tool for teeth, a handle-side housing attached to the housing and provided with an air supply passage and an exhaust passage for the impeller, The deviations in the orientation of the air supply passage opening, which is a communication hole for the air supply passage with respect to the internal space of the housing, and the exhaust passage opening, 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, are within the range of 35° to 155°. [Brief explanation of the drawing]

[0007] [Figure 1] A diagram illustrating the configuration of a dental handpiece as one embodiment of the present invention. [Figure 2] A schematic plan view of the impeller of a dental handpiece. [Figure 3] A diagram illustrating the configuration of the main parts of a dental handpiece as a first embodiment of the present invention. [Figure 4] A diagram illustrating the configuration of the main parts of a dental handpiece as a second embodiment of the present invention. [Figure 5] A diagram illustrating the configuration of the main parts of a dental handpiece as a third embodiment of the present invention. [Modes for carrying out the invention]

[0008] (composition) Figure 1 shows an impeller-type dental handpiece 1, which is one embodiment of the present invention. It 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 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 perspective 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 various shapes such as approximately elliptical, approximately rectangular, approximately trapezoidal, or approximately hexagonal.

[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 formed by a lid member, and by opening or removing the lid member, access to the internal space of the housing 11 may be made possible, allowing for the replacement of the impeller 2.

[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, respectively, at the upper shaft 201 and lower shaft 202. 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, for example, by fitting the upper part of the cutting tool 4 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 and is inclined 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 2.6-2.8). 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 heavy metals 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 within 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 its 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 FIG. 3, the communication hole (air supply communication hole O1) of the air supply passage 121 is arranged in the direction of the first azimuth angle θ1 in the clockwise direction with respect to the reference axis C when viewed from the central axis of the internal space of the housing 11, and the azimuth angle range is from θ1 - Δθ1 to θ1 + Δθ1. The first azimuth angle θ1 is included in the range of, for example, 15° to 30°. "Δθ1" is, for example, 2° to 2.5°. The angle φ1 formed by the air supply direction from the air supply passage 121 to the internal space of the housing 11 (the extending direction of the air supply passage 121 near the air supply communication hole O1) and the tangential direction of the internal space is included in the range of, for example, 0° to 60° or 15° to 60°.

[0018] The communication hole (exhaust communication hole O2) of the exhaust passage 122 is arranged in the direction of the second azimuth angle θ2 in the counterclockwise direction with respect to the reference axis C when viewed from the central axis of the internal space of the housing 11, and the azimuth angle range is from θ2 - Δθ2 to θ2 + Δθ2. The second azimuth angle θ2 is larger than the first azimuth angle θ1 and is included in the range of, for example, 20° to 90°, preferably in the range of 20° to 55°. "Δθ2" is, for example, 1° to 2.5°. The angle φ2 formed by the exhaust direction from the internal space of the housing 11 to the exhaust passage 122 (the extending direction of the exhaust passage 122 near the exhaust communication hole O2) and 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 supply communication hole O1 and the exhaust communication hole O2 are arranged in two azimuths separated by an azimuth deviation θ1 + θ2 (for example, 35° to 120°) when viewed from the central axis of the internal space of the housing 11. Δθ1 (or the area of the air supply communication hole O1) and Δθ2 (or the area of the exhaust communication hole O2) may be the same, or either one may be larger than the other.

[0020] (Function and effect) According to the dental handpiece 1 of this configuration, compressed air is supplied into the internal space of the housing 11 by the operation of the operator through the air supply conduit 101 and the air supply passage 121 from the compressor. In the air supply circuit communicating with the compressor, the supply amount of the compressed air is adjusted by an air supply amount adjusting mechanism constituted by a pedal or the like of the chair unit. In the internal space of the housing 11, the impeller 2 is rotationally driven by the compressed air, and treatment such as cutting of the patient's teeth is performed by the cutting tool 4 coaxially attached to the shaft 20 of the impeller 2. The compressed air is discharged to the outside of the dental handpiece 1 through the exhaust passage 122 and the exhaust conduit 102 from the internal space of the housing 11.

[0021] According to the findings obtained by the present inventor, when each of the air supply communication hole O1 and the exhaust communication hole O2 is arranged in each of two directions where the azimuth deviation θ1 + θ2 is less than 35° when viewed 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 presumably because the air flow from the air supply passage 121 toward the internal space of the housing 11 and the air flow from the internal space of the housing 11 toward the exhaust passage 122 interfere with each other, and a vortex flow is generated in the vicinity of the exhaust communication hole O2.

[0022] In view of this finding, in the present embodiment, each of the air supply communication hole O1 and the exhaust communication hole O2 is arranged in each of two directions where the azimuth deviation θ1 + θ2 is 35° or more and separated by 35° to 120° when viewed from the central axis of the internal space of the housing 11. For this reason, the interference of the air flow as described above is suppressed, and as a result, the exhaust efficiency from the internal space of the housing 11 to the exhaust passage 122 is improved, and further, the rotation efficiency of the impeller 2 and the cutting efficiency of the object by the tip or cutting edge of the cutting tool 4 are improved. Furthermore, reduction of the volume generated by the high-speed rotation of the impeller 2 by the compressed air is also achieved.

[0023] (Second Embodiment) Figure 4 shows a first embodiment of the arrangement of the air supply passage 121 and the exhaust passage 122 within 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 components 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 and Benefits) 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° from 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 and Benefits) 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] (modified version) In the third embodiment, the impeller 2 was 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 was 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, in the range of 5° to 10°). [Industrial applicability]

[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. [Explanation of symbols]

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

Claims

1. Housing and An impeller for rotating a cutting tool for teeth is rotatably arranged around an axis within the internal space of the housing, The housing comprises a handle-side housing attached to the aforementioned housing, which is provided with an air intake passage and an exhaust passage for the impeller, The deviation in orientation of the air supply passage opening (a communication hole for the air supply passage) and the exhaust passage opening (a communication hole for the exhaust passage) relative to the internal space of the housing, with respect to the central axis of the housing, falls within the range of 35° to 155°. Dental handpiece.

2. In the dental handpiece according to claim 1, With reference to a reference axis that extends perpendicularly to the central axis along the longitudinal direction of the handle-side housing, as viewed from the central axis of the internal space of the housing, the air intake port is positioned in a direction that is a first azimuth angle in a clockwise direction, and the exhaust port is positioned in a direction that is a second azimuth angle greater than the first azimuth angle in a counterclockwise direction. Dental handpiece.

3. In the dental handpiece according to claim 2, 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°. Dental handpiece.

4. In the dental handpiece according to claim 3, 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°. Dental handpiece.

5. In the dental handpiece according to claim 1, In a plan view with the central axis of the internal space of the housing perpendicular to it, the angle between the extending direction of the respective air intake 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°. Dental handpiece.

6. In the dental handpiece according to claim 1, The distance of the exhaust communication hole relative to the rotation region of the impeller is configured to be greater than the distance of the intake communication hole relative to the rotation region of the impeller. Dental handpiece.

7. In the dental handpiece according to claim 6, The impeller is eccentrically positioned within 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. Dental handpiece.

8. In the dental handpiece according to claim 6 or 7, 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. Dental handpiece.

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