JP2012205643A - Air turbine handpiece - Google Patents

Abstract

To prevent negative pressure from being generated in a turbine chamber due to inertial rotation of turbine blades when use of a handpiece is terminated and intake air is stopped, and to improve turbine rotation efficiency.
In a handpiece having a head part, a neck part, and a grip part, and having an air supply pipe and an exhaust pipe, the exhaust pipe is connected to the exhaust pipe as a reflux inlet. An exhaust gas recirculation line 16 is formed which opens at one end and opens an exhaust outlet 17 as the other end to the turbine chamber 15. The diameter of the recirculation outlet 17 of the recirculation line 16 is set to the air supply port of the air supply line 11. The value divided by the aperture of 14 is set to 1 or less, and the reflux outlet 17 of the reflux conduit 16 is opened to the turbine chamber 15 near the air supply port between the air supply port 14 and the exhaust outlet 17. It was composed by doing.
[Selection] Figure 1

Description

  In the present invention, even if the supply air for driving the turbine is stopped, the turbine blades rotate by inertia and negative pressure is generated in the turbine chamber. Therefore, in order to prevent this negative pressure generation, the exhaust gas after driving the turbine is supplied The air turbine that recirculates the exhaust gas after driving the turbine to the air supply side and reinforces the driving force of the turbine by injecting the air supply toward the turbine blades while the turbine is being driven. Regarding handpieces.

  The conventional air turbine handpiece cuts off the supply of pressurized air, which is a driving medium, when the driving of the turbine is finished. However, even if the supply of pressurized air is interrupted, the turbine blades continue to rotate by inertia due to their own inertia, so that the air in the turbine chamber is discharged by this rotation and negative pressure is generated in the turbine chamber. Further, since the space in the turbine chamber communicates with the outside air through a gap near the rotating shaft, the outside air is sucked into the turbine chamber due to the negative pressure inside, and the patient's saliva, blood, etc. Of contaminants are aspirated. As a result, the inside of the head part and / or the inside of the joint fitting or the supply / exhaust hose connected to the handpiece is contaminated. If the inside of the handpiece is contaminated in this way, there is a risk of cross-infection between the patient, the operator, or between patients through the handpiece. Various techniques have been developed to improve this problem. For example, the inventions of Patent Documents 1 to 7 described below are publicly known.

  The invention of Patent Document 1 has an air supply line for supplying compressed air from a compressed air source to an air turbine and an exhaust line for exhausting the air, and an air supply valve is connected to the air supply line. A negative pressure is generated in the handpiece by closing the air supply valve and the exhaust valve at the same time when driving of the handpiece is completed, or by closing the air supply valve after closing the exhaust valve. And prevents inhalation of contaminants into the handpiece.

  The invention of Patent Document 2 is supplied to an impeller rotatably accommodated in an inner space formed in a head portion of a handpiece, an air supply port for supplying air toward the impeller, and an impeller. An exhaust port for discharging the air, one or a plurality of buffer spaces in which centrifugal force is supplied by rotation of the impeller and stored in a pressurized state, and an additional pressure stored in the buffer space. A passage for releasing compressed air into the atmosphere from around the tool rotating with the impeller, and a circumferential position to provide resistance to the air moving between the exhaust port and the impeller and moving from the impeller to the exhaust port And a buffer space facing the rotational direction of the impeller.

  And even if the handpiece of this structure ends the driving of the handpiece and stops air supply, the air in the turbine chamber is exhausted by the inertial rotation of the impeller, but is interposed between the impeller and the exhaust port. The flow of air moving from the impeller toward the exhaust port is obstructed by the side wall, and the air rotating together with the impeller is in a buffer space formed outside the impeller based on the centrifugal force applied to the air. Is accumulated in a pressurized state. Furthermore, sucking back can be prevented by discharging the accumulated air to the atmosphere from the periphery of the tool through an air passage formed in the head portion.

  The invention of Patent Document 3 is provided with means for preventing the pressure medium rotating in the turbine chamber from being discharged through the discharge pipe during inertial rotation of the turbine impeller after the supply of the pressure medium is stopped. In a handpiece, particularly for medical or dental purposes, the means are arranged in the region of the turbine chamber and, in functional operation, deflect the pressure medium rotating in the turbine chamber beyond the outlet opening. And a flow web projecting into the flow of the pressure medium rotating by the means and forming a flow stage for the pressure medium rotating in functional operation, Prevents function and inhalation or suck back. The intermediate web is then positioned approximately in the middle transverse plane of the turbine impeller so that the inlet opening is positioned substantially in alignment with the inlet channel that exists between the intermediate web and the associated sidewall of the turbine chamber. The intermediate web is said to increase the power of the turbine by extending in a convergent direction or obliquely with respect to the inflow direction with the round web tip facing in the rotational direction.

  The invention of Patent Document 4 is a manual dental apparatus having an air passage for supplying driving air to a turbine and an exhaust air passage that is directly connected to the cylindrical surface of the turbine chamber and exhausts from the turbine chamber. It opens in the vicinity of the axis of the turbine chamber through the connection passage and in the region between the rotor and the tool-side bearing, or the exhaust air passage is located on the tool side of the bearing provided on the tool side, Open to the cylindrical wall via a connection passage or an exhaust air passage is provided in the region near the axis of the turbine chamber and / or in the hollow chamber near the tool operating mechanism on the side opposite to the tool side of the rotor. The connection passage connected to the exhaust air passage opens in a region around the shaft, thereby preventing outside air from being sucked in by negative pressure generated by inertial rotation of the rotor. It is.

  In the invention of Patent Document 5, as the form 1, the chamber of the head unit has a nozzle opening for ejecting air toward the turbine blade part of the rotor, and an exhaust port for discharging the ejected air to the outside And the width W of the arc-shaped nozzle opening along the circumferential direction of the turbine blade portion is set to be not less than twice the height H of the rotor in the rotation axis direction. To do.

  In this handpiece, the circumferential arc width W of the nozzle opening for injecting air toward the turbine blade portion is set to be twice or more the height H in the rotation axis direction of the rotor, and the nozzle opening is Because of the long shape in the circumferential direction, the air injected from the nozzle opening acts intensively in the axial center of the turbine blade of the turbine blade part, and the area of the nozzle opening is large, so the amount of feed The rotor can be efficiently driven with high torque.

  Further, as a second embodiment of the present invention, it is disposed in a chamber formed in the head portion, and is rotatably supported by bearing means integrally with the rotating shaft, and a tool is detachably mounted on the rotating shaft. Each of the rotor blades includes a hub portion and a plurality of turbine blades provided on the outer peripheral surface of the hub portion at substantially equal intervals in the circumferential direction. The turbine blade includes a first blade portion that extends substantially in a circular arc shape in the rotational direction of the rotor, and a direction that is substantially continuous to the first blade portion and away from the first blade portion. An air turbine handpiece having a second wing portion extending rearward in the rotation direction of the rotor, and a nozzle opening for ejecting air toward the first wing portion of the turbine blade in the chamber. , The air blown toward the turbine blades is discharged to the outside The outer peripheral surface of the hub portion extends in a concave arc shape radially inward from the upper end to the lower end, and the first of the turbine blades extends from the nozzle opening. The air ejected to the wing part is guided by the first wing part and flows backward in the rotation direction, and is further guided by the second wing part toward the direction away from the first wing part. It is guided downward in the rotational direction and is then discharged to the outside through the discharge opening.

  In the handpiece having this configuration, each turbine blade of the rotor is separated from the first blade portion, which extends substantially in an arc shape in the rotational direction of the rotor, and from the first blade portion. And a second blade portion extending rearward in the rotational direction, and air from the nozzle opening is injected toward the first blade portion of the turbine blade. Therefore, the air injected from the nozzle opening flows backward in the rotational direction along the arcuate surface of the first wing part, and is further guided in the rotational direction along the second wing part following the first wing part. As a result, the flow of air flowing along the turbine blades becomes smooth. Therefore, the air injected toward the turbine blade portion flows smoothly along the turbine blade, hardly acts as a rotational resistance, and the rotor can be efficiently rotated. In the present invention, since the outer peripheral surface of the hub portion extends in a concave arc shape radially inward from the upper end to the lower end, the air from the nozzle opening acts on the hub portion to reduce the rotational torque of the rotor. You can go up.

  Further, as the third aspect of the present invention, the outer peripheral surface of the first portion, which is the upper portion of the hub portion, extends in an arc shape in a concave shape radially inward from the upper end to the lower end, and is a second portion that is the lower portion of the hub portion The outer peripheral surface of the portion extends downward in the rotational axis direction of the rotor. The present invention is characterized in that a part of the air ejected from the nozzle opening is guided to the turbine blades after being guided by the first and second portions of the hub portion. The handpiece having this configuration includes a first portion in which the hub portion of the turbine blade portion extends in a substantially arc shape inward in the radial direction of the rotor, and a first portion extending from the first portion in the rotational direction of the rotor. Therefore, a part of the air jetted from the nozzle opening that acts on the hub portion is guided from the first portion to the turbine blade along the second portion. The rotational torque of the rotor is increased by acting on the rotor.

  In the invention of Patent Document 6, the diameter of the exhaust port at the inlet end of the exhaust passage is set larger than the diameter of the air inlet at the tip of the air passage, and the inside of the housing from the air inlet to the exhaust port is circulated. The air passage is expanded sequentially from the air supply port to the exhaust port side, and the turbine blades are connected to two upper and lower units with the same rotating shaft, and a separator is provided between the two turbines. The head portion chamber and the air supply passage, exhaust passage and air passage in the neck portion are separated into two systems corresponding to each turbine. Further, in addition to the above configuration, the gap between the turbine blade and the upper and lower inner wall surfaces of the chamber is narrowed, and in particular, the torque for rotating the cutting tool is increased.

  In the above, the first turbine blade and the second turbine blade have a narrow vertical gap between the turbine blade and the upper and lower inner wall surfaces of the chamber when viewed from the axial direction of the rotating shaft, and the pressurized air injected to the turbine blade has a vertical gap. It prevents sudden diffusion due to the air gap so that the air supply speed does not decrease. In addition, the diameter of the exhaust port that circulates in the chamber of the head housing and exhausts air is set larger than the diameter of the air supply port of the air supply path, and the air passage extending from the air supply port to the exhaust port is The cross-sectional area is sequentially increased starting from the air supply port at the front end of the passage, and the exhaust port is made to coincide with the diameter of the exhaust passage. The radius of curvature is sequentially increased from the air supply port to reach the exhaust port.

  In the handpiece having this configuration, the turbine blade is rotated by the impact pressure of the pressurized air injected from the air supply port, and then the interior of the chamber is viewed along the inner wall surface in a clockwise direction when the head portion is viewed from above. At this time, the volume of the chamber, which is a ventilation path, gradually expands starting from the air supply port, so the pressurized air does not diffuse rapidly and the air supply speed is rapidly reduced. The resistance action that prevents the rotation of the turbine blades is prevented. Furthermore, since the volume of the exhaust is made the same as that of the exhaust path at the exhaust port, the flow of pressurized air that circulates inside the chamber during the supply and exhaust processes passes through sequentially enlarged portions in the chamber. It reaches the exhaust port having the same diameter as that of the exhaust passage, and the air density is gradually reduced, so that it is possible to prevent the resistance action that reduces the rotation of the turbine blade.

  In addition, the first turbine blade and the second turbine blade are connected to each other, the rotation shaft is the same, and the torque power is doubled at the same rotation speed. In addition, the air supply and exhaust systems are divided into two parts, upper and lower, corresponding to the upper and lower two turbines, thereby reducing air supply loss. For this reason, a shaft-side separator and a housing-side separator are provided between the upper and lower turbine blades, and the above-described action greatly improves the efficiency of the turbine and increases the torque of the rotating cutting tool.

  The invention of Patent Document 7 provides a rotor for a dental air turbine handpiece, the rotor being perpendicular to the rotation axis and having a thickness that equally divides an air receiving band located around the rotor blades. It has a flywheel, and the position of this flywheel may take a high position or a low position, but preferably takes an intermediate position, and when taking this intermediate position, to propel the rotor, It is more efficient. In addition, when the vertical plane of each wedge in the upper row is regularly overlapped with the vertical plane of each wedge in the lower row, it increases the number of air drives per rotation of the rotor and increases the starting speed. In addition, the torque can be maintained in a high rotation state. The overlap of the vertical surfaces of the upper wedges with respect to the vertical surfaces of the lower wedges may be offset by a half band. In addition, only one air jet can be used, but in order to increase efficiency, a normal one air jet is divided into two or more jets with the same diameter or a smaller diameter to form a wedge-shaped It effectively concentrates the arrival of pressurized air at the central air receiving zone, allowing an increase in starting speed and maintaining torque at high rotational speeds.

Japanese Patent Laid-Open No. 06-047060 WO 2006/101133 Japanese Patent No. 4100833 Japanese Patent No. 3907284 Japanese Patent No. 3208345 Japanese Patent No. 3684643 JP-A-01-104254

  However, in the case of Patent Document 1, it is necessary to provide an air supply valve and an exhaust valve, and further an electric signal for operating the exhaust valve (an electric signal for operating the electromagnetic valve) or an air signal (for operating the air valve) Air signal) is required. In order to make the circuit work more effectively, it is necessary to operate the air supply valve after the exhaust valve is closed, and a control circuit that operates in this order is indispensable. In addition, parts and circuits need to be added, resulting in an increase in cost. Furthermore, this circuit is applied to a product newly shipped from a factory, and there is a problem that it is difficult to deal with an existing product on the market.

  In the case of Patent 2, in addition to the air supply port for supplying air toward the impeller at the head part of the handpiece and the discharge port for the supplied air, centrifugal force is generated by rotation of the impeller in the head part. Is located between the exhaust port and the impeller, and the circumferential direction that provides resistance to the air flowing from the impeller to the exhaust port. It is necessary to provide a side wall. In order to effectively demonstrate the effect, the buffer space can be prevented from sucking back by opening in the rotational direction of the impeller, so the structure is complicated and complicated, and the cost is increased. There is a problem of becoming.

  In the case of Patent Document 3, since the processing of the outlet opening arranged in the turbine chamber region, the flow groove leading to the outlet opening, and the web is complicated and the cost is increased, the structure is simple and economical. There is a problem that the product of can not be provided. Then, due to the arrangement of the intermediate web positioned on the almost horizontal plane of the turbine impeller and the inlet opening or the related side wall of the turbine chamber, the intermediate web flows in a state where the round web tip is directed in the rotational direction. It is said that the power of the turbine is increased by extending in a convergent direction or obliquely with respect to the direction, but this is a smooth relationship between the shape of the intermediate web, the inlet opening, and the path leading to the outlet opening. The flow is thought to have been successful, but the degree of "increased power" is not shown. In addition, providing the intermediate web on the turbine impeller is extremely complicated and further increases the cost.

  In the case of Patent Document 4, there is a problem that it is not easy to process the connection passage that communicates with the exhaust air passage and opens in the region around the shaft, and the cost increases as described above. Although the present invention has a configuration similar to that of the present invention, unlike the present invention, the connection passage communicating with the exhaust air passage is opened to a region around the shaft away from the negative pressure generating portion of the turbine chamber, etc. It does not directly prevent the generation of negative pressure, but alleviates the influence of the generated negative pressure, and further increases the processing cost in terms of structure, and is a completely different configuration.

  Form 1 of Patent Document 5 is intended to rotate at high torque by efficiently applying air jetted toward the turbine blade portion of the rotor to a plurality of turbine blades (in the flow direction). However, it is necessary to set the width W of the nozzle opening for jetting air toward the turbine blade part to be set to at least twice the height H in the rotation axis direction of the rotor, and a normal nozzle diameter of 1.0 mm to 1.5 mm There is a problem in that it is not easy to widen the opening of a certain degree to more than twice the height H (usually about 3.0 mm to 3.5 mm), and the cost is increased as described above.

  In form 2, the air jetted from the nozzle opening flows backward in the rotational direction along the arcuate surface of the first wing part, and further in the rotational direction along the second wing part following the first wing part. It is guided and flows along the turbine blades, and the air flow is smooth. Therefore, the air injected toward the turbine blade portion flows smoothly along the turbine blade, hardly acts as a rotational resistance, and can rotate the rotor efficiently. Further, since the outer peripheral surface of the hub portion extends in a concave arc shape radially inward from the upper end to the lower end, air from the nozzle opening acts on the hub portion and increases the rotational torque of the rotor. I can do it. The shape of such a rotor (consisting of each turbine blade) can only be formed in a three-dimensional (substantially three-dimensional) form, and it is imagined that the complexity of processing and creating a processing program cannot be exhausted. Is done. Furthermore, it is not difficult to imagine that a lot of processing time is consumed, and the cost is greatly increased.

  Form 3 is that part of the air jetted from the nozzle opening that acts on the hub portion is guided to the turbine blades from the first part along the second part, and acts on the turbine blades. This contributes to the rotational torque of the rotor and can increase the rotational torque of the rotor. In this case, the shape of the rotor composed of each turbine blade is not only three-dimensional (substantially three-dimensional) as described above, but also consists of two upper and lower turbine blade groups, with the lower stage having a small diameter (substantially inverted cone). It can be imagined that the complexity of the machining and creation of the machining program cannot be exhausted. Furthermore, it is not difficult to imagine that a lot of processing time is consumed, and the cost is greatly increased.

  In the case of Patent Document 6, it is necessary to process the exhaust passage so that the radius of curvature is sequentially increased from the air supply port to reach the exhaust port, and the (chamber) inner wall of the substantially cylindrical head is the center of the head. The exhaust passage must be formed while being eccentric with respect to the (rotor rotating shaft) successively, and it is obvious that the processing is complicated even when compared with the present invention. Furthermore, when the first turbine blade and the second turbine blade are connected to each other, it has been proposed to divide the air supply and exhaust system into two upper and lower parts corresponding to the upper and lower two turbines. Adding an exhaust system increases the number of processing steps and increases costs.

  In the case of Patent Document 7, it is possible to increase the starting speed and maintain the torque in a high rotation state, and it is a main matter of the invention to incorporate a so-called “flywheel” in a part of the rotor. Therefore, the rotational driving force of the air turbine handpiece of the present application is enhanced, which is different from the one that has an energy saving effect.

  As described above, all of Patent Documents 1 to 7 are complicated in structure and costly. In addition, in the air turbine handpiece of the present application, supply air, which is a main requirement, is injected into the turbine chamber and at the same time exhaust gas is discharged from the turbine. There is no disclosure of a configuration that enhances the driving force by returning to the chamber to provide an energy saving effect and prevents negative pressure from being generated in the turbine chamber by returning exhaust gas to the turbine chamber when driving is stopped.

  Therefore, in view of the problems in Patent Documents 1 to 7, the present invention causes negative pressure in the turbine chamber due to inertial rotation of the turbine blades even when supply of air is stopped for the end of turbine driving of the handpiece. In order to prevent this, the exhaust gas is recirculated to the turbine chamber. While the turbine is being driven, the exhaust gas is recirculated to the turbine chamber, and at the same time, the supply air is injected toward the turbine blades to increase the rotational driving force of the turbine blades. It was developed for the purpose.

  The inventor of the present invention, in the previously filed invention (Japanese Patent Application No. 2010-211589 Air Turbine Handpiece), generates negative pressure in the turbine chamber due to the inertial rotation of the turbine blades even when the air supply for driving the turbine is stopped. In order to solve the problem that contaminants such as the patient's saliva and blood are inhaled into the head together with the outside air at the negative pressure, a technique for preventing the generation of the negative pressure has been disclosed. Thereafter, as a result of further research related to the technology of the invention, the inventor of the present application recirculated the exhaust gas after driving the turbine to the turbine chamber in addition to the negative pressure generation prevention technology, and simultaneously supplied air to the turbine blades. We have developed a technology that can significantly improve the driving force by spraying.

Claim 1 of the present invention is a head portion in which a turbine chamber is formed and a rotatable turbine blade is provided in the turbine chamber, a neck portion connected to the head portion and gripped by an operator, An air supply line for supplying air from an air supply port to drive the turbine blade, and an exhaust port after the turbine blade is rotated by supply air In the handpiece provided with an exhaust pipe for exhausting from the exhaust pipe, the exhaust pipe is formed with an exhaust gas reflux pipe that opens at one end as a reflux inlet and opens an exhaust outlet at the other end into the turbine chamber. A value obtained by dividing the diameter of the reflux outlet of the reflux pipeline by the diameter of the air supply inlet of the air supply pipeline is set to 1 or less, and the reflux outlet of the reflux pipeline is the air outlet Supply port and front The air turbine handpiece is configured by opening the turbine chamber near the air supply port between the exhaust outlet and the turbine chamber. A head portion provided with rotatable turbine blades in the turbine chamber, a neck portion connected to the head portion and gripped by an operator, and a grip portion connected to the rear of the neck portion; and In the handpiece provided with an air supply line for supplying air from an air supply port for driving the turbine blades and an exhaust line for discharging from the exhaust port after rotating the turbine blades with supply air, the exhaust line And forming an exhaust gas recirculation line that opens at one end as a recirculation inlet and opens an exhaust outlet as the other end to the turbine chamber, and The diameter of the outlet is set as D ₀ : D ₁ = 1: 0.62 to 0.92 when the air supply diameter of the air supply pipe is D ₀ and the diameter of the reflux outlet is D ₁ , And the said recirculation | reflux outlet of the said recirculation | reflux pipe line was comprised by opening to the turbine chamber of the vicinity of the said air supply port between the said air supply port and the said exhaust outlet,
According to a third aspect of the present invention, when the diameter of the reflux outlet is D ₀ and the diameter of the reflux outlet is D ₁ , D ₀ : D ₁ = 1: It is configured to be set as 0.77, and the reflux outlet of the reflux conduit is configured by opening a turbine chamber in the vicinity of the air supply between the air supply port and the exhaust outlet. An air turbine handpiece according to claim 2.

  In the air turbine handpiece according to the present invention, the most negative pressure is generated in the turbine chamber by opening the other end of the reflux conduit having one end communicating with the exhaust conduit into the turbine chamber near the air supply port of the air supply conduit. Exhaust gas can be directly recirculated to an easy-to-use part, and generation of negative pressure can be efficiently prevented by the recirculated exhaust gas. As a result, when negative pressure is generated in the air turbine handpiece, foreign matter can be prevented from being sucked into the handpiece, and crossover between the patient / operator or patients occurring through the air turbine handpiece can be prevented. It becomes possible to prevent infection. Furthermore, by setting the value obtained by dividing the reflux outlet diameter of the reflux pipeline by the air supply port diameter of the air supply pipeline to 1 or less (≦ 1), the air supply pipeline is connected to the turbine blades while the handpiece is in use. In addition to the air supply injected toward the air, the amount of air supply is increased by the recirculation exhaust supplied to the negative pressure generating portion of the turbine chamber via the recirculation conduit, and the rotational driving force of the air turbine handpiece is enhanced. Energy saving effect is obtained. Further, since the configuration of the reflux pipe is simple and easy to process, the air turbine handpiece can be provided at a low price.

(A) and (b) are longitudinal and transverse sectional views showing a configuration in which a reflux pipe is opened toward a turbine chamber in the vicinity of an air supply port. These are explanatory drawings of the action of reflux. It is a diagram which shows the rotation speed and power of a turbine drive which recirculated exhaust gas. It is a diagram which shows the reflux pipe line diameter and power of a turbine drive which recirculated exhaust gas. FIG. 2 is a perspective view showing the appearance of the entire air turbine handpiece.

  The purpose of preventing negative pressure in the turbine chamber due to inertial rotation of the turbine blades even when the intake air for driving is stopped to stop the driving of the air turbine handpiece is to connect the reflux inlet at one end to the exhaust pipe. This can be achieved with a simple configuration by providing a reflux conduit that opens to the passage and opens the reflux outlet at the other end to the turbine chamber near the air supply port of the air supply conduit. In addition, for the purpose of enhancing the rotational driving force of the handpiece and saving energy, the value obtained by dividing the reflux outlet diameter of the reflux conduit by the air supply orifice of the air supply conduit is set to 1 or less (≦ 1) Could be achieved.

  As shown in FIG. 5, the air turbine handpiece 1 of the present embodiment to which the present invention is applied includes a neck portion 2 gripped by an operator, a head portion 3 connected to the tip side of the neck portion 2, and a neck The grip part 4 is connected to the rear of the part 2, and a hose 5 containing a supply pipe and an exhaust pipe (not shown) is connected to the rear end of the grip part 4.

  As shown in FIG. 1, a turbine chamber 15 is formed inside the head portion 3 of the air turbine handpiece 1, and a turbine blade 6 positioned inside the air chamber handpiece 1 is fixed to a chuck 8 that supports a tool 7, and the chuck 8 is interposed therebetween. These are rotatably supported by a pair of upper and lower ball bearings 9. A push button 10 is provided at the upper end of the chuck 8 so that the tool 7 can be attached and detached by pressing the push button 10 against the bias of the spring 10a. Further, an air supply pipe 11 for rotating the turbine blade 6 and an exhaust pipe 12 for discharging the air after rotating the turbine blade 6 are provided on the neck part 2 side of the head part 3, and the air supply pipe is further provided. A nozzle 13 is connected to the outlet side of the passage 11, and air is jetted from the air supply port 14 formed at the tip of the nozzle 13 toward the turbine chamber 15.

  In the present embodiment, in the above-described configuration, the reflux pipe 16 is connected to the exhaust pipe 12 via the exhaust gas reflux inlet 19, and the reflux outlet 17 at the other end of the reflux pipe 16 is connected to the air supply pipe 11. The turbine chamber 15 is opened near the air supply port 14. In the air turbine handpiece 1 having this configuration, when the air supply from the air supply pipe 11 is stopped, a part of the exhaust gas flowing into the exhaust pipe 12 is recirculated as shown by the arrows in FIG. 16 flows from the recirculation outlet 17 to the A region near the air supply port 14 in the turbine chamber 15. This A region is the portion where the negative pressure is most likely to be generated when the intake is stopped, and the exhaust gas directly recirculates to this A region, so that the generation of the negative pressure can be efficiently prevented. Furthermore, during the turbine driving of the handpiece 1, in addition to the supply air injected from the air supply port 14, that is, the pressurized supply air, the reflux exhaust flows into the turbine chamber near the air supply port via the return conduit 16, The air supply amount is increased, and the rotational driving force of the turbine is enhanced. This makes it possible to achieve an energy saving effect.

However, the enhancement of the rotational driving force will be described because the following test is conducted. As an example, when the diameter of the air supply port 14 in FIG. 1 is 1.3 mm, the vertical axis of FIGS. 3 (a) to 3 (g) shows the power on the vertical axis and the rotational speed on the horizontal axis. In the case where the circuit 16 is not provided, the maximum work rate is 23.50 W at 200,000 revolutions. On the other hand, with the reflux circuit 16 (b), 230,000 revolutions at 23.66 W, (c) 230,000 revolutions at 25.91 W, (d) 250,000 revolutions at 27.48 W, (e) 240,000 revolutions 25.53 W in (f), 26.34 W at 240,000 revolutions, and 23.44 W in 230,000 revolutions in (g). Since the setting is set to 0.22 MPa (2.2 bar), the air supply amount is not constant but tends to decrease. By providing a recirculation circuit 16 and returning the exhaust gas to the turbine chamber 15, the amount of supplied air increases. As a result, the rotation speed increases from 200,000 to 250,000 rotations, and the work rate is increased as indicated by the arrows in the figure. It was confirmed that it was remarkably improved.

 In addition, when the diameter of the air supply port 14 in FIG. 1 is 1.3 mm, the conventional type in which the reflux line 16 is not formed in the diagram in which the vertical axis in FIG. In the air turbine handpiece 1, the maximum work rate is 23.50 W, whereas in the air turbine handpiece of the present invention in which the reflux pipe 16 is formed, the work amount is 26.95 around the diameter 1 mm of the reflux outlet 17 of the reflux pipe 16. W and the maximum value, indicating that the work volume has increased significantly.

  From the above test results, the reflux port diameter 17 of the reflux circuit 16 is effective when the diameter of the air supply port 14 is 0.8 mm to 1.2 mm with respect to 1.3 m, and gradually increases within the range of 0.8 mm or less and 1.2 mm or more. The effect tends to decrease. Further, it was found that 1.0 mm to 1.2 mm was preferable among 0.8 mm to 1.2 mm, and 1.0 mm was most preferable.

  Therefore, in the present invention, the reflux outlet diameter for efficiently increasing the rotational driving force when the turbine blade height is 3 mm and the air supply port diameter is 1.3 mm is that the reflux outlet diameter is 1.0 mm to 1.2 mm. Is preferred, with 1.0 mm being most preferred. Expressing this in terms of aperture ratio, the value obtained by dividing the reflux outlet diameter by the air supply aperture is preferably 1 or less, effectively 0.62 to 0.92, and most preferably 0.77. It was.

  It is well known to those skilled in the art that if the diameter of the air supply port is made smaller than 1.3 mm due to the capacity of the turbine chamber 15, the rotational speed will increase too much. In other words, the diameter is not limited to the above-mentioned diameter as long as the rotation speed of the turbine blade 6 does not increase excessively, that is, the diameter is such that the air can be supplied to the extent that noise does not increase. On the other hand, if the diameter of the air supply port is larger than 1.3 mm, there is a concern that the rotational speed of the turbine blade 6 cannot be 300000 rpm to 400000 rpm, preferably 350,000 rpm to 400000 rpm. However, as long as a constant flow rate (desired rotation speed) can be maintained, the diameter is not limited to the above-mentioned diameter even if the diameter of the air supply port is larger than 1.3 mm.

As described above, when the air supply is stopped, the air turbine handpiece of the present invention can efficiently prevent the exhaust gas from returning to the turbine chamber in the vicinity of the air supply port 14 and generating a negative pressure in the turbine chamber. Further, during the turbine drive, the amount of air supplied to the turbine chamber 15 is increased by returning the exhaust gas to the turbine chamber in addition to the supply air injected from the air supply pipe 11 to the turbine chamber, and the turbine blade 6 The rotational driving force is increased. Thereby, an energy-saving effect can be produced. Note that exhaust gas recirculation when the turbine drive is stopped is not limited to the above, and may be performed in the vicinity of the air supply port 14. Further, the diameters of the air supply pipe 11 and the reflux pipe 16 are not limited to the above. Also, the structure is simple and can be provided at a low price.

1 Air turbine handpiece
2 neck
3 Head
4 Grip part
5 hose
6 Turbine blade
7 Tools
8 Chuck
9 Ball bearing
10 Push button
11 Air supply line
12 Exhaust pipe
13 nozzles
14 Air supply port
15 Turbine room
16 Reflux line
17 Return outlet
18 Exhaust vent
19 Return inlet

Claims (3)

A head part in which a turbine chamber is formed and a rotatable turbine blade is provided in the turbine room, a neck part connected to the head part and gripped by an operator, and a rear part of the neck part And an air supply line for supplying air from an air supply port to drive the turbine blades, and an exhaust line for exhausting air from the exhaust port after rotating the turbine blades with supply air In the handpiece
The exhaust pipe is formed with an exhaust gas reflux pipe that opens at one end as a reflux inlet and an exhaust outlet at the other end into the turbine chamber, and the diameter of the reflux outlet of the reflux pipe is The value divided by the diameter of the air supply port of the air supply line is set to 1 or less, and the return outlet of the return line is the air supply between the air supply port and the exhaust outlet An air turbine handpiece characterized by being configured by opening in a turbine chamber in the vicinity of the mouth. A head part in which a turbine chamber is formed and a rotatable turbine blade is provided in the turbine room, a neck part connected to the head part and gripped by an operator, and a rear part of the neck part And an air supply line for supplying air from an air supply port to drive the turbine blades, and an exhaust line for exhausting air from the exhaust port after rotating the turbine blades with supply air In the handpiece
An exhaust gas recirculation pipe having one end as a recirculation inlet and an exhaust outlet as the other end opened to the turbine chamber is formed in the exhaust pipe, and the air supply port diameter of the air supply pipe is D _0. the diameter of the return outlet when the D _1, the diameter of the return outlet of the return _{line, D 0: D 1 = 1} : set configured as from 0.62 to 0.92, and of the return line An air turbine handpiece configured by opening the reflux outlet into a turbine chamber near the air supply port between the air supply port and the exhaust outlet. Configuration is set as _0.77: said air supply aperture of the air supply conduit and D _0, the diameter of the return outlet when the D _1, the diameter of the return outlet, _{D 0:} D 1 = 1 And the recirculation outlet of the recirculation pipe is configured to open in a turbine chamber near the air supply port between the air supply port and the exhaust outlet. Air turbine handpiece.

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