Patent Description:
Patent Literatures <NUM> and <NUM> disclose that a dental handpiece provided with a rotation mechanism such as an air turbine or an air motor driven to rotate by compressed air includes a pressure regulating mechanism that regulates a pressure of the compressed air to an appropriate range in order to reduce occurrences of damage to a dental treatment tool due to a high rotation speed of the rotation mechanism and wear due to a shortage of a lubricating oil.

As shown in <FIG>, a pressure regulating mechanism includes a cylindrical piston <NUM>, an air supply pipe <NUM> is disposed inside the piston <NUM>, and a case <NUM> is disposed outside the piston <NUM>. The piston <NUM> is axially slidable between the air supply pipe <NUM> and the case <NUM>, and is biased to one side in an axial direction by a coil spring <NUM> accommodated in the case <NUM>. In this pressure regulating mechanism, when a pressure of compressed air is applied to an end surface of the piston <NUM> opposite to the coil spring <NUM> and the pressure becomes larger than an urging force of the coil spring <NUM>, the piston <NUM> slides to the other side in the axial direction against the urging force of the coil spring <NUM>. Then, a hole 5a formed in the case <NUM>, which is normally closed by the piston <NUM>, communicates with a hole 3a formed in the air supply pipe <NUM>, and the compressed air supplied into the air supply pipe <NUM> passes through the holes 3a, 5a to outside of the case <NUM> to regulate the pressure.

Patent Literature <NUM> discloses a dental handpiece capable of regulating air pressure supplied to a head part. A coupling adapter is embedded in a body part of the handpiece and fastened to a coupling part so as to deliver compressed air and supply water to the head part, wherein the coupling adapter further has an air pressure regulating part having a discharge hole connected to an air supply passage and, when the pressure of the air supplied through an air supply pipe is a set pressure or higher, opens the discharge hole so as to enable the air pressure supplied through the air supply pipe to be maintained at a predetermined pressure or lower.

Patent Literature <NUM> discloses a further example of a dental handpiece.

Components such as the piston <NUM>, the air supply pipe <NUM>, and the case <NUM> constituting the pressure regulating mechanism described above are required to be processed with high accuracy such that a gap between the components is <NUM> or smaller, for example, in order to reduce a leakage of air. Therefore, a manufacturing cost increases.

Even if the components are processed with high accuracy, it is difficult to completely stop the leakage of air from the gap between the components. As a result, energy loss of the compressed air may occur and lead to a decrease in torque or rotational speed in a rotation mechanism.

In addition, since the structure has the cylindrical piston <NUM> slidable in the axial direction, an entire length may become long. Therefore, a large accommodation space may be required, which leads to an increase in a size of the entire handpiece.

An object of the present invention is to provide a dental handpiece that efficiently utilizes supply air energy and is miniaturized while reducing a manufacturing cost.

According to an aspect of the present invention, there is provided a dental handpiece according to claim <NUM>.

According to the present disclosure, supply air energy is efficiently utilized and a size is reduced while reducing a manufacturing cost.

<FIG> is a side view of a gripping portion <NUM> of a dental handpiece <NUM> according to the present invention as viewed in a cross section along an axial direction.

As shown in <FIG>, the dental handpiece <NUM> according to the present embodiment includes a gripping portion <NUM> and a head portion <NUM>. The head portion <NUM> is provided at a front end of the gripping portion <NUM>, and a dental treatment tool <NUM> is attached to the head portion <NUM>. The dental handpiece <NUM> according to the present embodiment is an air turbine type handpiece in which the dental treatment tool <NUM> is rotated by compressed air.

The gripping portion <NUM> includes a case <NUM> formed in a cylindrical shape, and an air supply pipe <NUM> and a water supply pipe <NUM> are provided inside the case <NUM>. The air supply pipe <NUM> includes a pressure regulating mechanism <NUM> on a rear end side thereof. The water supply pipe <NUM> includes a check valve <NUM> on a rear end side thereof. An internal space of the case <NUM> of the gripping portion <NUM> serves as an exhaust flow path <NUM>.

A rear end of the gripping portion <NUM> serves as a connection portion <NUM>, and a coupling member (not shown) is connected to the connection portion <NUM>. A flexible tube (not shown) extending from a dental unit (not shown) that supplies compressed air and water is connected to the coupling member. Compressed air supplied from the dental unit is supplied to the air supply pipe <NUM> of the gripping portion <NUM>. The compressed air supplied to the air supply pipe <NUM> passes through the pressure regulating mechanism <NUM> and is supplied toward the head portion <NUM>. Water supplied from the dental unit is supplied to the water supply pipe <NUM> of the gripping portion <NUM>. The water supplied to the water supply pipe <NUM> passes through the check valve <NUM> and is supplied toward the head portion <NUM>. In the water supply pipe <NUM>, backflow of water is reduced by the check valve <NUM>.

<FIG> is a cross-sectional view of the head portion <NUM> of the dental handpiece <NUM>.

As shown in <FIG>, the head portion <NUM> includes a head housing <NUM> that accommodates a rotation mechanism <NUM> therein. The rotation mechanism <NUM> includes a bar sleeve <NUM>, a rotor <NUM>, a pair of ball bearings <NUM>, and a cartridge case <NUM>.

The bar sleeve <NUM> detachably holds the rod-shaped dental treatment tool <NUM>, and the rotor <NUM> is provided on an outer periphery of the bar sleeve <NUM>. The pair of ball bearings <NUM> are provided in the cartridge case <NUM>. Both end portions of the bar sleeve <NUM> are rotatably supported by the ball bearings <NUM>.

In the head portion <NUM>, the compressed air supplied from the air supply pipe <NUM> is blown to the rotor <NUM>. Thereby, the bar sleeve <NUM> holding the dental treatment tool <NUM> is rotated. The compressed air blown to the rotor <NUM> is discharged from the head portion <NUM> to the exhaust flow path <NUM> formed by the internal space of the case <NUM> of the gripping portion <NUM>.

A discharge port <NUM> communicating with the water supply pipe <NUM> is provided in a portion of the gripping portion <NUM> in vicinity of the head portion <NUM>, and the water supplied from the water supply pipe <NUM> is discharged from the discharge port <NUM>. An ejection port <NUM> communicating with a branch passage <NUM> branched from the air supply pipe <NUM> is provided at a position adjacent to the discharge port <NUM>, and the compressed air supplied from the branch passage <NUM> is ejected from the ejection port <NUM>. Thereby, in the dental handpiece <NUM>, in vicinity of a front end of the head portion <NUM>, the compressed air is ejected from the ejection port <NUM> together with the water discharged from the discharge port <NUM>, so that the water can be ejected in a spray form.

<FIG> is a cross-sectional view along the axial direction in vicinity of the rear end of the gripping portion <NUM> of the dental handpiece <NUM>. <FIG> is a perspective view of the pressure regulating mechanism <NUM>. <FIG> is a cross-sectional view of the pressure regulating mechanism <NUM> taken along the axial direction.

As shown in <FIG>, the pressure regulating mechanism <NUM> provided in the air supply pipe <NUM> includes a pipe body <NUM> having a pressure regulating portion <NUM>. The pressure regulating portion <NUM> of the pipe body <NUM> includes balls <NUM> and an annular elastic member <NUM>.

The pipe body <NUM> is formed in a tubular shape including a flow path <NUM>. In the pipe body <NUM> includes one end portion 51a to which the air supply pipe <NUM> is connected, and the other end portion <NUM>1b to which a connection portion (not shown) of an end portion of the flexible tube extending from the dental unit that supplies compressed air is connected. The other end portion 51b of the pipe body <NUM> is held by an adapter <NUM> constituting the connection portion <NUM> of the gripping portion <NUM>.

The pipe body <NUM> includes a fitting hole <NUM> having an inner diameter larger than that of the flow path <NUM> on one end portion 51a side, and an end portion of the air supply pipe <NUM> is fitted and connected to the fitting hole <NUM>. An O-ring <NUM> is provided in the fitting hole <NUM>, and a gap between the fitting hole <NUM> and the air supply pipe <NUM> is sealed by the O-ring <NUM>.

The pipe body <NUM> includes a large diameter portion <NUM> on the one end portion 51a side and a small diameter portion <NUM> formed to have a diameter smaller than that of the large diameter portion <NUM> on the other end portion 51b side.

The pipe body <NUM> is provided with the pressure regulating portion <NUM> at a position of the large diameter portion <NUM> in vicinity of the small diameter portion <NUM> side. The pressure regulating portion <NUM> includes a plurality of holes <NUM> penetrating a pipe wall of the pipe body <NUM> from front to back surfaces. In this example, the pipe body <NUM> includes three holes <NUM>, and these holes <NUM> are formed at equal intervals in a circumferential direction. The balls <NUM> are accommodated in the holes <NUM>, respectively.

A groove <NUM> is formed in an outer periphery of the large diameter portion <NUM> of the pressure regulating portion <NUM> of the pipe body <NUM>. The groove <NUM> is formed in the circumferential direction at a position passing through positions where the holes <NUM> are formed. The groove <NUM> has a width smaller than a diameter of the ball <NUM> accommodated in the hole <NUM>.

The annular elastic member <NUM> is made of, for example, an elastic material such as rubber, and is formed in an annular shape. The annular elastic member <NUM> is formed in a circular shape in cross section. For example, an O-ring may be used as the annular elastic member <NUM>. The annular elastic member <NUM> is fitted to an outer periphery of the pipe body <NUM>, and is accommodated in the groove <NUM> formed in the large diameter portion <NUM>. The annular elastic member <NUM> fitted to the outer periphery of the pipe body <NUM> and accommodated in the groove <NUM> is accommodated in the groove <NUM> without protruding from an outer peripheral surface of the pipe body <NUM>, and positional deviation in an axial direction of the pipe body <NUM> is reduced.

In a state where the annular elastic member <NUM> is accommodated in the groove <NUM>, a clearance C is formed between the annular elastic member <NUM> accommodated in the groove <NUM> and an inner peripheral surface of the hole <NUM> at a position on the outer periphery of pipe body <NUM> where the hole <NUM> is formed.

<FIG> is a cross-sectional view taken along a line VI-VI in <FIG>.

As shown in <FIG>, the hole <NUM> formed in the pressure regulating portion <NUM> of the pipe body <NUM> includes a small diameter hole 67a having an inner diameter smaller than a diameter of the ball <NUM> on an inner peripheral side of the pipe body <NUM>. The ball <NUM> is accommodated in the hole <NUM> from an outer peripheral side of the pipe body <NUM>. The ball <NUM> accommodated in the hole <NUM> is locked to the small diameter hole 67a on the inner peripheral side of the pipe body <NUM> in the hole <NUM>, and movement of the pipe body <NUM> to the inner peripheral side is restricted.

The ball <NUM> accommodated in each hole <NUM> is urged toward the inner peripheral side of the pipe body <NUM> by an elastic force of the annular elastic member <NUM> fitted to the outer periphery of the pipe body <NUM> and accommodated in the groove <NUM>. Thereby, the ball <NUM> accommodated in each hole <NUM> is brought into a state of abutting against an edge portion of the small diameter hole 67a of the hole <NUM>, and each hole <NUM> is maintained in a state of being closed by the ball <NUM>.

In the dental handpiece <NUM> including the pressure regulating mechanism <NUM> having the above-described structure, compressed air is supplied from the dental unit through the flexible tube connected by the coupling member. The supplied compressed air passes through the pipe body <NUM> constituting the pressure regulating mechanism <NUM> and is supplied to the air supply pipe <NUM>. Then, in the head portion <NUM>, the compressed air is blown from the air supply pipe <NUM> to the rotor <NUM>, and the bar sleeve <NUM> holding the dental treatment tool <NUM> is rotated. The compressed air blown to the rotor <NUM> is discharged from the head portion <NUM> to the exhaust flow path <NUM> formed by the internal space of the case <NUM> of the gripping portion <NUM>, and is discharged to a dental unit side through an exhaust path of the flexible tube.

At this time, the compressed air may be supplied from the dental unit at a pressure exceeding an appropriate range. In this case, in the pressure regulating mechanism <NUM>, as an internal pressure of the air supply pipe <NUM> increases, the ball <NUM> accommodated in each hole <NUM> of the pressure regulating portion <NUM> of the pipe body <NUM> is displaced outward in a radial direction of the pipe body <NUM> against a urging force of the annular elastic member <NUM>. Then, each of the balls <NUM> is separated from the edge portion of the small diameter hole 67a of the hole <NUM>, the compressed air in the pipe body <NUM> flows out from a gap between the hole <NUM> and the ball <NUM> to the exhaust flow path <NUM> on the outer peripheral side of the pipe body <NUM>, and the internal pressure of the air supply pipe <NUM> is maintained in an appropriate range.

As described above, according to the dental handpiece <NUM> of the present embodiment, since a pressure of the supplied compressed air is maintained in the appropriate range by the pressure regulating part <NUM> of the pressure regulating mechanism <NUM> provided in the air supply pipe <NUM>, in the rotation mechanism <NUM>, occurrences of damage to the dental treatment tool <NUM> due to a high rotation speed of the bar sleeve <NUM> and wear due to a shortage of a lubricating oil are avoided.

The pressure regulating portion <NUM> of the pressure regulating mechanism <NUM> has a structure in which the ball <NUM> is accommodated in the hole <NUM> formed in the pipe body <NUM>, and the ball <NUM> is biased from the outer peripheral side by the annular elastic member <NUM> fitted to the pipe body <NUM>. Therefore, the number of components is be reduced and a cost of the component itself is reduced as compared with a pressure regulating mechanism having a related-art structure in which compressed air is regulated by a piston slidable in an axial direction.

Since there is no component that slides in the axial direction, a length in the axial direction may be shortened to reduce a size, and accommodating is easily performed in a narrow space in the gripping portion <NUM>.

It is possible to avoid a loss of supply air energy due to a leakage of the compressed air from a gap between the components.

In the above embodiment, the pressure regulating portion <NUM> is provided in the pipe body <NUM> separate from the air supply pipe <NUM>, but the pressure regulating mechanism <NUM> may be configured by providing the pressure regulating portion <NUM> in a pipe body formed of the air supply pipe <NUM>. According to this structure, the number of components is further reduced.

Next, a modification of the pressure regulating mechanism provided in the dental handpiece <NUM> will be described. Components the same as those of the pressure regulating mechanism <NUM> according to the above-described embodiment are denoted by the same reference numerals, and description thereof will be omitted.

<FIG> is a perspective view of a pressure regulating mechanism 21A according to a first modification. <FIG> is a cross-sectional view of the pressure regulating mechanism 21A according to the first modification, taken along an axial direction. <FIG> is a cross-sectional view taken along a line IX-IX in <FIG>.

As shown in <FIG> and <FIG>, the pressure regulating mechanism 21A according to the first modification includes a pipe body <NUM> including two pressure regulating portions 50A.

The pipe body <NUM> is formed in a tubular shape including a flow path <NUM>. The pipe body <NUM> includes one end portion 71a to which the air supply pipe <NUM> is connected, and the other end portion 71b to which a connection portion of a flexible tube extending from a dental unit that supplies compressed air is connected.

The pipe body <NUM> includes a fitting hole <NUM> in which the O-ring <NUM> is provided on one end portion 71a side, and an end portion of the air supply pipe <NUM> is fitted and connected to the fitting hole <NUM>. The flow path <NUM> of the pipe body <NUM> includes a small diameter flow path portion 77a on a fitting hole <NUM> side.

The pipe body <NUM> includes an intermediate diameter portion <NUM> on the one end portion 71a side, and a small diameter portion <NUM> formed to have a diameter smaller than that of the intermediate diameter portion <NUM> on the other end portion 71b side. In the pipe body <NUM>, an intermediate portion of the intermediate diameter portion <NUM> in the axial direction is formed as a large diameter portion <NUM> having a larger diameter. The two pressure regulating portions 50A are provided in the large diameter portion <NUM> of the pipe body <NUM>, and are disposed at an interval in the axial direction. A relief portion 74a for avoiding interference with the water supply pipe <NUM> is formed in a portion of the large diameter portion <NUM> of the pipe body <NUM> at a water supply pipe <NUM> side.

The pressure regulating portion 50A includes one hole <NUM> that accommodates the ball <NUM>, and a groove <NUM> having a width smaller than a diameter of the ball <NUM> is formed at a position passing through a position where the one hole <NUM> is formed. The annular elastic member <NUM> is accommodated in the groove <NUM>.

As shown in <FIG>, the hole <NUM> formed in the pipe body <NUM> includes a small diameter hole 67a on an inner peripheral side of the pipe body <NUM>, and further includes a large diameter hole 67b on an outer peripheral side of the pipe body <NUM>. The ball <NUM> accommodated in the hole <NUM> from the outer peripheral side of the pipe body <NUM> is locked to the small diameter hole 67a on the inner peripheral side of the pipe body <NUM> in the hole <NUM>, and movement of the pipe body <NUM> to the inner peripheral side is restricted. In the pressure regulating portion 50A, the ball <NUM> is urged by an elastic force of the annular elastic member <NUM> to abut against an edge portion of the small diameter hole 67a of the hole <NUM>, whereby the hole <NUM> is maintained in a state of being closed by the ball <NUM>.

In the pressure regulating mechanism 21A according to the first modification, when compressed air is supplied from the dental unit at a pressure exceeding an appropriate range, the ball <NUM> accommodated in the hole <NUM> of each pressure regulating portion 50A of the pressure regulating mechanism 21A is displaced outward in a radial direction of the pipe body <NUM> against an urging force of the annular elastic member <NUM>. Thereby, the ball <NUM> is separated from the edge portion of the small diameter hole 67a of the hole <NUM>, and the compressed air in the pipe body <NUM> flows out from a gap between the hole <NUM> and the ball <NUM> to the exhaust flow path <NUM> on the outer peripheral side of the pipe body <NUM>.

Each pressure regulating portion 50A regulates a pressure in the one hole <NUM> that accommodates the ball <NUM>. Therefore, the large diameter hole 67b is formed on the outer peripheral side of the pipe body <NUM> in the hole <NUM>, and air is easily discharged at the time of pressure regulation. For the same purpose, a material of the annular elastic member <NUM> may be selected to adjust the elastic force, so that the air can be easily released at the time of pressure regulation.

As described above, also in a case of the pressure regulating mechanism 21A according to the first modification, when the compressed air exceeds the appropriate range, the compressed air is discharged from each pressure regulating portion 50A provided in the pipe body <NUM>, and thus an internal pressure of the air supply pipe <NUM> is maintained in the appropriate range. Thereby, in the rotation mechanism <NUM>, occurrences of damage to the dental treatment tool <NUM> due to a high rotation speed of the bar sleeve <NUM> and wear due to a shortage of a lubricating oil are reduced.

In the pressure regulating mechanism 21A according to the first modification, the ball <NUM> biased by the annular elastic member <NUM> is accommodated in the one hole <NUM> of each pressure regulating portion 50A, so that a structure is simplified.

Since the plurality of pressure regulating portions 50A are provided at the interval in the axial direction of the pipe body <NUM>, redundancy is provided in a pressure regulating function, and safety is enhanced.

<FIG> is a cross-sectional view of a pressure regulating mechanism 21B according to a second modification, taken along an axial direction.

As shown in <FIG>, the pressure regulating mechanism 21B according to the second modification is attached to a branch pipe <NUM> provided in the air supply pipe <NUM>. One end of the branch pipe <NUM> is connected to the air supply pipe <NUM>, and an intermediate portion thereof is bent and extends along the air supply pipe <NUM>. The pressure regulating mechanism 21B is connected to the other end of the branch pipe <NUM>.

The pressure regulating mechanism 21B includes a pipe body <NUM>, and the pressure regulating portion <NUM> is provided in the pipe body <NUM>. The pipe body <NUM> is formed in a bottomed tubular shape. The pipe body <NUM> includes a fitting hole <NUM> provided with the O-ring <NUM>, and an end portion of the branch pipe <NUM> branched from the air supply pipe <NUM> is fitted and connected to the fitting hole <NUM>. The pipe body <NUM> includes a large diameter portion <NUM> on an end portion side opposite to a connection side with the branch pipe <NUM>, and the large diameter portion <NUM> is provided with the pressure regulating portion <NUM> in which the balls <NUM> are accommodated in three holes <NUM> and the balls <NUM> are biased by the annular elastic member <NUM>.

In the pressure regulating mechanism 21B according to the second modification, when compressed air is supplied from a dental unit at a pressure exceeding an appropriate range, an internal pressure of the pipe body <NUM> of the pressure regulating mechanism 21B connected to the branch pipe <NUM> increases, and the balls <NUM> accommodated in the respective holes <NUM> of the pressure regulating portion <NUM> are displaced outward in a radial direction of the pipe body <NUM> against an urging force of the annular elastic member <NUM>. As a result, each ball <NUM> is separated from the edge portion of the small diameter hole 67a of the hole <NUM>, the compressed air in the pipe body <NUM> flows out from a gap between the hole <NUM> and the ball <NUM> to the exhaust flow path <NUM> on an outer peripheral side of the pipe body <NUM>, and an internal pressure of the air supply pipe <NUM> is maintained in an appropriate range.

As described above, also in a case of the pressure regulating mechanism 21B according to the second modification, when the compressed air exceeds the appropriate range, the compressed air is discharged from the pressure regulating portion <NUM> provided in the pipe body <NUM>, and thus the internal pressure of the air supply pipe <NUM> is maintained in the appropriate range. Thereby, in the rotation mechanism <NUM>, occurrences of damage to the dental treatment tool <NUM> due to a high rotation speed of the bar sleeve <NUM> and wear due to a shortage of a lubricating oil are reduced.

Since the pressure regulating mechanism 21B according to the second modification is provided in the branch pipe <NUM> branched from the air supply pipe <NUM>, a supply path of the compressed air may be shortened, and an entire length of the dental handpiece <NUM> may be further shortened.

In the second modification, the pressure regulating portion <NUM> may be provided in a branch pipe that branches off from the air supply pipe <NUM> and further joins the air supply pipe <NUM>. In this case, the compressed air branched from the air supply pipe <NUM> to the branch pipe passes through the pressure regulating portion <NUM> of the branch pipe and joins the air supply pipe <NUM>.

As described above, the present invention is not limited to the above-described embodiment, and combinations of the configurations of the embodiment and modifications and applications by those skilled in the art based on the description of the specification and well-known techniques are also intended to be made by the present invention and are included in the scope required for protection.

As described above, the following matters are disclosed in the present specification.

According to this dental handpiece, when a pressure of the supplied compressed air exceeds an appropriate range in the pressure regulating portion provided in the air supply pipe, the ball accommodated in the hole is displaced outward in a radial driection of the pipe body against an urging force of the annular elastic member by the pressure. Thereby, the compressed air in the pipe body flows out to the outer peripheral side of the pipe body from a gap between the hole and the ball, and the pressure of the compressed air is maintained in the appropriate range. Thereby, in the rotation mechanism, occurrences of damage to the dental treatment tool due to a high rotation speed of the bar sleeve and wear due to a shortage of a lubricating oil are reduced.

The pressure regulating portion has a structure in which the ball is accommodated in the hole formed in the pipe body, and the ball is biased from the outer peripheral side by the annular elastic member fitted to the pipe body. Therefore, the number of components isreduced and a cost of the component itself is reduced as compared with a pressure regulating mechanism having a related-art structure in which compressed air is regulated by a piston slidable in an axial direction.

Since there is no component that slides in the axial direction, a length in the axial direction may be shortened to reduce a size, and accommodating is easily performed in a narrow space in the gripping portion.

As described above, according to the dental handpiece of the present invention, the supply air energy is efficiently utilized and the dental handpiece is miniaturized while reducing a manufacturing cost.

(<NUM>) The dental handpiece according to (<NUM>),
wherein a pressure regulating mechanism including the pressure regulating portion is connected to the air supply pipe.

According to this dental handpiece, a pressure regulating function is easily provided to the air supply pipe by the pressure regulating portion of the pressure regulating mechanism connected to the air supply pipe.

(<NUM>) The dental handpiece according to (<NUM>) or (<NUM>),.

According to the dental handpiece, the balls are accommodated in the plurality of holes formed at intervals in the circumferential direction, and the balls are pressed from the outer peripheral side of the pipe body by the annular elastic member. Therefore, when the pressure of the compressed air exceeds the appropriate range, the balls in the holes are displaced, and the pressure of the compressed air may be rapidly reduced.

(<NUM>) The dental handpiece according to any one of (<NUM>) to (<NUM>),.

According to this dental handpiece, the ball accommodated in the hole is locked by the small diameter hole, so that the ball is arranged at an appropriate position of the hole.

According to this dental handpiece, a clearance is formed between the annular elastic member accommodated in the groove and an inner peripheral surface of the hole at a position on the outer periphery of the pipe body where the hole is formed. Thereby, the compressed air is smoothly discharged from the clearance.

(<NUM>) The dental handpiece according to any one of (<NUM>) to (<NUM>),
wherein a plurality of the pressure regulating portions are provided at intervals in an axial direction of the pipe body.

According to this dental handpiece, since the plurality of pressure regulating portions are provided at intervals in the axial direction of the pipe body, redundancy is provided in the pressure regulating function, and safety is enhanced.

(<NUM>) The dental handpiece according to any one of (<NUM>) to (<NUM>),
wherein the pressure regulating portion is provided in a branch pipe branched from the air supply pipe.

Claim 1:
A dental handpiece (<NUM>) comprising:
a head portion (<NUM>) including a bar sleeve (<NUM>) that is configured to detachably hold a dental treatment tool (<NUM>), and a rotation mechanism (<NUM>) that is configured to rotate the bar sleeve by compressed air; and
a tubular gripping portion (<NUM>) including a front end provided on which the head portion (<NUM>) is disposed and an air supply pipe (<NUM>) that is configured to supply the compressed air to the rotation mechanism (<NUM>),
wherein the air supply pipe (<NUM>) includes a pressure regulating portion (<NUM>; 50A) that regulates a pressure of the compressed air in the air supply pipe, and
the pressure regulating portion includes:
a pipe body (<NUM>; <NUM>; <NUM>) through which the compressed air passes; and
a hole (<NUM>) penetrating a pipe wall of the pipe body;
characterised in that the pressure regulating portion further includes:
a ball (<NUM>) accommodated in the hole to close the hole; and
an annular elastic member (<NUM>) that is fitted to the pipe body and urges the ball from an outer peripheral side of the pipe body.