AIR TURBINE HANDPIECE

Abstract

An air turbine handpiece having: a head portion with built-in free turbine blade, a neck portion installed consecutively with the head portion and grasped by an operator, a grip portion installed consecutively with the neck portion, an air supply duct for driving the turbine blade, and an exhaust duct for exhausting the air. The exhaust duct is provided with a reflux duct, open at one end to the exhaust duct, and open at the other end to the turbine room as the exhaust exit, a value in which an aperture at the reflux exit of the reflux duct is divided by an aperture in the air supply port of the air supply duct, becomes one or less, and the reflux exit of the reflux duct is opened to the turbine room near the air supply port between the air supply port and the exhaust exit.

Claims

1. Air turbine handpiece comprising a head portion forming therein a turbine chamber, in which a rotatable turbine blade is provided; a neck portion installed consecutively with the head portion and grasped by an operator; a grip portion installed consecutively with the neck portion behind thereof; an air supply duct for charging air from an air supply port to drive the turbine blade; and an exhaust duct for exhausting the air from the exhaust vent after rotating the turbine blade by the charged air; the exhaust duct is provided with a reflux duct for the exhausting, one end of the reflux duct is opened to the exhaust duct as an reflux entry, and the other end of the reflux duct is opened to the turbine duct as an exhaust exit, characterized in that the reflux duct is constituted in such a manner that a value in which an aperture at the reflux exit of the reflux duct is divided by an aperture in the air supply port of the air supply duct, becomes one or less, and a reflux exit of the reflux duct is opened to the turbine chamber close to the air supply port between the air supply port and the exhaust exit.

2. Air turbine handpiece as claimed in claim 1, characterized in that the reflux duct is constituted in such a manner that when the aperture in the air supply port of the air supply duct is assumed to be D.sub.0, and the aperture at the reflux exit is assumed to be D.sub.1, the aperture at the reflux exit of the reflux duct is set as D.sub.0:D.sub.1=1:0.69 to 0.92, and the reflux exit of the reflux duct is opened to the turbine chamber close to the air supply port between the air supply port and the exhaust exit.

3. Air turbine handpiece comprising a head portion forming therein a turbine chamber, in which a rotatable turbine blade is provided; a neck portion installed consecutively with the head portion and grasped by an operator; a grip portion installed consecutively with the neck portion behind thereof; an air supply duct for charging air from an air supply port to drive the turbine blade; and an exhaust duct for exhausting the air from the exhaust port after rotating the turbine blade by the charged air; characterized in that the air supply duct is install consecutively with a nozzle, and the exhaust duct is provided with a reflux duct, one end of the reflux duct is opened to the exhaust duct as an reflux entry, and the other end of the reflux duct is opened to closed to the air supply port of the nozzle as an exhaust exit.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0045] FIG. 1 shows first embodiment of an air turbine handpiece according to the present invention, and

[0046] FIGS. 1(a), (b) are a vertical cross-sectional view and a cross-sectional view showing the constitution of the reflux duct opened toward the turbine room near at the air supply port,

[0047] FIG. 2 is an operational explanatory view of the reflux in the air turbine handpiece of the first embodiment,

[0048] FIG. 3 is a diagram showing the rotational speed and the power of the refluxed turbine-drive as for the exhaust in the air turbine handpiece of the first embodiment,

[0049] FIG. 4 is a diagram showing the reflux duct aperture and the power of the refluxed turbine-drive as for the exhaust in the air turbine handpiece of the first embodiment,

[0050] FIG. 5 shows second embodiment of the air turbine handpiece according to the present invention, and

[0051] FIGS. 5(a), (b) are a vertical cross-sectional view and a cross-sectional view showing the constitution of the reflux duct opened toward the turbine room near at the air supply port,

[0052] FIG. 6 is an operational explanatory view of the reflux in the air turbine handpiece of the second embodiment,

[0053] FIG. 7 is a perspective view showing external appearance of the entire air turbine handpiece.

DETAILED DESCRIPTION

[0054] Even if inspired air for the drive is stopped to stop the drive of the air turbine handpiece, the object of preventing negative pressure from being generated in the turbine room by inertia rotation of the turbine blade, can be achieved with a simple constitution, by providing the reflux duct in such a manner that one end as reflux entry is opened to the exhaust tube and the other end as reflux exit is opened to the turbine room near the air supply port of the air supply port. Moreover, the object that the rotation driving force of the handpiece is reinforced and energy-saving effect is attempted, can be achieved by setting a value in which an aperture at the reflux exit of the reflux duct is divided by an aperture in the air supply port of the air supply duct, becomes one or less (1).

First Embodiment

[0055] As shown in the FIG. 7, an air turbine handpiece 1 of this embodiment that applies the present invention comprises a neck portion 2 grasped by an operator, a head portion 3 installed consecutively to the tip side of the neck portion 2, and a grip portion 4 installed consecutively behind the neck portion 2, and a hose 5 with built-in feed pipe and exhaust pipe (not shown) is connected with the rear end of the grip portion 4.

[0056] As shown in FIG. 1, a turbine room 15 is formed in the interior of the head portion 3 of the air turbine handpiece 1, and a turbine blade 6 is fixed to a chuck 8 that supports a tool 7, in interior of the turbine room 15, and is rotatably supported by ball bearings 9 of one pair of upper and lower sides through the chuck 8. Moreover, on the upper end of the chuck 8, the tool 7 is constructed detachably by compressing a pushbutton 10 against energization of a spring 10a. Furthermore, at the side of the neck portion 2 of the head portion 3, an air supply line 11 for rotating the turbine blade 6 and an exhaust duct 12 for exhausting air after the turbine blade 6 is rotated, are provided, and additionally, a nozzle 13 is installed consecutively to the exit side of the air supply line 11, so that air is jetted from an air supply port 14 formed to the tip of the nozzle 13 toward a turbine room 15.

[0057] In this embodiment, a reflux duct 16 is installed consecutively to the exhaust duct 12 through a reflux entry 19 for exhausting, in the above constitution, and a reflux exit 17 of the other end of the reflux duct 16 is opened in the turbine room 15 near the air supply port 14 of the air supply line duct 11. According to the air turbine handpiece 1 of the above constitution, in the case of stopping the air supply with the air supply duct 11, as shown in FIG. 2 by an arrow (a), a part of exhaust flowed into the exhaust duct 12 flows from the reflux exit 17 into the area A of the air supply port 14 in the turbine room 15 near through the reflux duct 16. The area A is a portion where the negative pressures are generated easily most when inspired air is stopped, by refluxing the exhaust in this area A directly, so that the negative pressure can be efficiently prevented from being generated. Furthermore, during the turbine-drive of the air turbine handpiece 1, supply air jetted from the air supply port 14, that is, the reflux exhaust in addition to the pressurizing charge flows into the turbine room 15 of the air supply port near through the reflux duct 16, so that the air supply quantity increases, and the rotation driving force of the turbine is reinforced. As a result, the energy-saving efficacy can be effected.

[0058] However, as to the reinforcement of the rotation driving force, the followings are examined; the explanation thereof is as follows. As an example, in case that the diameter of the air supply port 14 in FIG. 1 is made 1.3 mm, in the diagram showing FIGS. 3(a) to (g), in which the power is taken as ordinates and the cycle is taken as abscissas, (a) is a case that reflux duct 16 is not installed, and the highest power 23.50 W is shown by 200,000 rotations of the turbine. On the other hand, hereinafter, there is shown the relation between the highest power and the cycle in the case that the reflux duct 16 was installed. 23.66 W every 220,000 rotations in (b). 25.91 W every 230,000 rotations in (c). 27.48 W every 250,000 rotations in (d). 25.53 W every 240,000 rotations in (e). 26.34 W every 240,000 rotations in (f). 23.44 W every 230,000 rotations in (g). In each air turbine handpiece where the reflux duct diameter was changed, the pressure in hand at the no-load running is set to 0.22 MPa (2.2 bar), so that the supply quantity of air is not constant, and is a tendency to decrease. It could identify an effect to which by installing the reflux duct 16 and returning the exhaust to the turbine room 15, the amount of the supply air increases, consequently, the cycle increases from 200,000 to 250,000 rotations, and as show by an arrow in FIG. 3, the power could be remarkably improved.

[0059] Moreover, in the case that the diameter of the air supply port 14 in FIG. 1 is made 1.3 mm, in the diagram shown in FIG. 4, in which the power is took as ordinates and the diameter of 21 exit at the reflux duct is took as abscissas, the maximum work becomes 23.50 W in the air turbine handpiece 1 of the old model that do not form the reflux duct 16 therein. It shows the effect that in the air turbine handpiece of the present application in which the reflux duct 16 is formed, the work becomes a maximum which is 26.95 W, near the diameter 1 mm of the reflux exit 17 of the reflux duct 16, and the power increased remarkably. On the other hand, it shows the effect that in the air turbine handpiece of the present application in which the reflux duct 16 is formed, the work becomes a maximum which is 26.95 W, near the diameter 1 mm of the reflux exit 17 of the reflux duct 16, and the power increased remarkably.

[0060] As is seen from the above-described result, as to the reflux exit 17 of the reflux duct 16, the effect is seen from 0.8 mm to 1.2 mm of the diameter relative to the diameter of 1.3 mm in the air supply port 14, and the effect shows a tendency to decrease gradually in the ranges of 0.8 mm or less and 1.2 mm or more. Also, it turned out that the diameter of the air supply port is made preferably, 1.0 mm to 1.2 mm among 0.8 mm to 1.2 mm, most preferably, 1.0 mm.

[0061] Thus, in the case that the height of the turbine blade in the present invention is made 3 mm, and a diameter of air supply port is made 1.3 mm, as a diameter of the reflux exit by which the rotation driving force is efficiently enhanced, the reflux exit diameter is made 1.0 mm to 1.2 mm, preferably, 1.0 mm. If this is represented by an aperture ratio, it became the most preferable result that a value in which an aperture of the reflux exit is divided by an aperture in the air supply port, becomes one or less, effectively 0.62-0.92, and 0.77 most preferably.

[0062] Moreover, if a diameter of the air supply aperture is made smaller than 1.3 mm according to the capacity of the turbine room 15, it is common knowledge in the same business that the rotating speed goes up too much. That is, if it is an aperture that the air supply of an extent where rotating speed of turbine blade 6 does not go up too much, that is, an extent where noise does not grow, becomes possible, the diameter of the air supply port cannot be limited to the above aperture thereof. Also, if the diameter of the air supply port is enlarged oppositely than 1.3 mm oppositely, it has misgivings about that the rotating speed 300,000 rpm-400,000 rpm, preferably, 350,000 rpm-400,000 rpm of the turbine blade 6, cannot be obtained. However, in case that a constant flow rate (desired rotating speed) can be kept, even if diameter of the air supply port is larger than 1.3 mm, the diameter of the air supply port cannot be limited to the above aperture thereof.

[0063] Therefore, according to the air turbine handpiece of the present invention, in the case of stop of the air supply, the exhaust is returned to the turbine room 15 nears the air supply port 14, and thus the negative pressure can be efficiently prevented from being generated in the turbine room. Moreover, during the turbine-drive, in addition to the charge jetted from the air supply duct 11 to the turbine room 15, the exhaust is returned to the turbine room, so that the amount of the air supplied to the turbine room 15 increases, and the rotation driving force of turbine blade 6 is reinforced. As a result, the energy-saving efficiency can be affected. Moreover, the reflux of the exhaust in the case of stop of turbine drive, is not limited to the above description, and can also be returned to the air supply port 14 nears. Also, the diameters of the air supply line 11 and the reflux duct 16 are not limited to the above description. Also, the structure is simple and can also be provided inexpensively.

Second Embodiment

[0064] FIG. 5 shows second embodiment of an air turbine handpiece of the present invention. As shown in FIGS. 5 (a) and (b), in an air turbine handpiece 1 according to the present embodiment 2, is constructed in such a manner that instead of the fact that the reflux exit 17 of the reflux duct 16 is opened to the air supply port 14 near the air supply duct 11 in the above first embodiment, the reflux exit 21 of the reflux duct 20 communicated with the reflux entry 22 opened to the exhaust duct 12, is opened to near the air supply port 14 in the nozzle 13 of the air supply duct 11 near.

[0065] In this case, when the supply of air from the air supply duct 11 is stopped, as shown in FIG. 6 by an arrow (b), the exhaust air exhausted by the inertia rotation of turbine blade 6 is entered in the nozzle 13 from the reflux exit 21 through the reflux entry 22 of reflux duct 20, and is flowed to the area A of the turbine blade 6. As a result, although in the case of present embodiment, the operational advantage similar to above first embodiment can be effected. Furthermore, in case of using the air turbine handpiece 1, the reflux exhaust flows into the nozzle 13, and is jetted into the turbine room 15 together with the pressurized charge, so that it will become help by which the reflux exhaust rotates and drives the turbine blade 6, and thus the secondary advantage can be effected.

[0066] According to the air turbine handpiece 1 of present embodiment 2, from the above, after the supply of the dissolved air from the air supply duct 11 is stopped, the turbine blade 6 rotates through inertia, so that even if the air in the turbine room 15 is sent into the exhaust port 18 and the negative pressure starts being generated near in the air supply port 14, this air flows into the area A being the negative pressure generation portion through the exhaust duct 16, and thus the negative pressure is canceled. Moreover, during use in the handpiece 1, the reflux air flows from the reflux duct 20 into the nozzle 13 of the air supply duct 11, and flows into the turbine blade 6 together with the dissolved air, so that the negative pressure is canceled. Moreover, during use in the handpiece 1, the reflux air flows from the reflux duct 20 into the nozzle 13 of the air supply duct 11, and jets toward the turbine blade 6 together with the dissolved air. As a result, the secondary efficiency that the rotation of turbine blade 6 can be helped can be effected.

[0067] To explaining in full as to help of the rotation, the reflux duct 16 is formed more thinly than the nozzle 13 connected to the air supply duct 11, and is opened to the interior of the nozzle 13 in the slope direction along the direction of the airflow, so that the negative pressure is generated at the reflux exit 21 by the dissolved air passed through the interior of the nozzle 13 with high speed, and thus the air in the reflux duct 20 is drawn in the nozzle 13. As a result, the refluxed air is jetted from the air supply port 14, in addition to the supplied and pressurized air, Moreover in the above description, in case of stopping the supply of air, the exhaust only has to be returned nears the air supply port 14, so that the diameter of the reflux duct 20 and mounting angle to the nozzle are not limited to the above description. Therefore, the structure of the air turbine handpiece 1 according to the present invention is simple and can be provided inexpensively.

EXPLANATIONS OF LETTERS OR NUMERALS

[0068] 1. Air turbine handpiece [0069] 2. Problem portion [0070] 3. Head portion [0071] 4. Grip portion [0072] 5. Hose [0073] 6. Turbine blade [0074] 7. Tool [0075] 8. Chuck [0076] 9. Ball bearing [0077] 10. Pushbutton [0078] 11. Air supply tube [0079] 12. Exhaust tube [0080] 13. Nozzle [0081] 14. Air supply port [0082] 15. Turbine room [0083] 16. Reflux duct line [0084] 17. Reflux exit [0085] 18. Exhaust vents [0086] 19. Reflux exit [0087] 20. Reflux entrance [0088] 21. Reflux exit [0089] 22. Reflux entrance