JP6541817B1 - HEAD COVER AND MEDICAL HANDpiece HAVING THE HEAD COVER - Google Patents

Abstract

An object of the present invention is to provide a head cover of a handpiece capable of preventing the head, which is hot, from coming into contact with the human body and cooling the head.
In order to solve the problem, a head cover for covering a head of a medical handpiece, wherein the head cover is attached to the handpiece and covers the head, a gap is formed between the head cover and the head. Configure the head cover to As a result, it is possible to prevent direct contact of the human body with a high temperature portion of the head and to secure a space for cooling that allows the head to dissipate heat from the surface, thereby providing a head cover. In addition, by providing the head cover on the handpiece, a highly safe handpiece can be provided.
[Selected figure] Figure 3

Description

  The present invention relates to a medical handpiece (hereinafter referred to as a handpiece) rotatably provided with a treatment tool for cutting a treatment site and rotating the treatment tool by a motor.

2. Description of the Related Art Conventionally, in the medical field of surgical treatment and dental treatment, treatment using a hand-held instrument called a hand piece has been performed.
The handpiece rotates the treatment tool provided on the head to cut and remove the affected area. In such a handpiece, a drive mechanism for rotating a tool holder for mounting a treatment tool provided therein may generate heat due to frictional heat during rotation, and the head may become hot.

In particular, such abnormal heat generation may occur when the maintenance such as sterilization, washing, lubrication or the like of the handpiece is insufficient.
Under such circumstances, there is known a technique for preventing the head of the handpiece, which has become hot, from directly touching the patient (see, for example, Patent Document 1). Patent Document 1 discloses a technique related to a head cover which is a member attached to a hand piece.

The handpiece described in Patent Document 1 is connected to an electric motor. A head cover is mounted to cover the head of the handpiece. That is, the head cover is composed of a cylindrical front annular area and a support area. And, the front annular area at least partially surrounds the head including the push button.
In addition, the head cover is made of a material having a lower thermal conductivity value as compared with the material of the portion constituting the outer shell such as the grip of the hand piece. For example, the head cover is made of synthetic resin.

  In the technique described in Patent Document 1, the head cover surrounds the head of the dental handpiece. As a result, even when a human body is in contact with the head cover while using the handpiece, it is possible to suppress the occurrence of burns and the like due to the heat of the head.

US Patent Application Publication No. 2012/0085561

In the technology described in Patent Document 1, the head that generates heat internally is surrounded by a material having a low heat conductivity value such as a synthetic resin. The effect of this material suppresses the temperature rise outside the head cover. That is, it is possible to prevent the high temperature portion of the head from directly touching the human body.
However, since the head cover is provided on the handpiece without a gap closely contacting the outer surface of the head, the heat radiation of the head itself inside the head cover is hindered by the effect of this material. That is, the head cover prevents the heat from being released from the surface of the head.
As a result, in the technique described in Patent Document 1, as compared with the case where the head cover is not attached, the head accumulates heat and becomes high temperature, and there is a possibility that the probability of occurrence of failure due to the high temperature state may increase.

  The problem to be solved by the present invention is to provide a head cover of a handpiece capable of cooling the head while preventing direct contact of the head, which is hot, with the human body.

In order to solve the problem, a head cover is provided for covering the head of a handpiece comprising a casing constituting a grip and having a motor unit connected to the rear end, and a head fixed to the front of the casing and having a treatment tool removably attached. The head includes a tool holder for holding the treatment tool inside, an upper bearing and a lower bearing for rotatably supporting the tool holder, and the treatment tool protrudes downward to the outside of the head When the head cover is attached to the handpiece , the head cover has a cylindrical protective portion in which the area facing rearward is notched, and the notched portion is sandwiched from the left and right and directed rearward from the protective portion. a pair of left and right has a holding portion, is widened away a pair of holding portions in the lateral direction elastic of returning to its original shape, viewed protective part from the upper direction extending In this case, the inner diameter of the protective portion is larger than the diameter of the cylindrical shape of the head, and the vertical size of the protective portion is equal to or larger than the height from the upper surface of the upper bearing to the lower surface of the lower bearing. In the state where the head cover is attached to the handpiece and covers the head, the head cover is provided inside the protective portion with a gap between the head cover and the head communicating with the space outside the head cover. while the position may be configured to cover as Ru attached to the handpiece at a write Mukoto pair of holding portions sandwich the side surfaces of the casing from the left and right direction by the elastic. Moreover, the problem can be solved by providing the head cover on the handpiece.

According to the present invention, it is possible to prevent direct contact of the human body with a high temperature portion of the head and to secure a space for cooling that allows the head to dissipate heat from the surface, thereby providing a head cover.
In addition, by providing the head cover on the handpiece, a highly safe handpiece can be provided.

It is a figure which shows the handpiece which concerns on Embodiment 1, (a) Top view of handpiece, (b) Side view of handpiece, (c) Bottom view of handpiece A diagram of the motor unit connected with the cross-sectional view of the XX position shown in FIG. 1 (a) Sectional view of only the head cover at the XX position shown in FIG. 1 (a) (A) Top view of head cover, (b) Side view of head cover It is a figure which shows the handpiece which concerns on Embodiment 2, (a) Top view of a handpiece, (b) Bottom view of a handpiece (A) Top view of head cover according to Embodiment 2, (b) Side view of head cover Sectional view of only the head cover at the XX position shown in FIG. 6 (a) (A) Side view of handpiece according to Embodiment 3, (b) Side view showing a state in which the head cover is discolored in response to high temperature Sectional view of only the head and the head cover of the handpiece in FIG. 8

Embodiment 1
Hereinafter, Embodiment 1 of the invention will be described with reference to the drawings.
FIG. 1 is a view showing a hand piece according to Embodiment 1, and is (a) a top view of the hand piece, (b) a side view of the hand piece, and (c) a bottom view of the hand piece. Fig.2 (a) is sectional drawing of the XX position shown to Fig.1 (a), and has shown the motor unit connected typically. FIG.2 (b) is the elements on larger scale of Fig.2 (a). FIG. 3 is a cross-sectional view of only the head cover at the position X-X shown in FIG. 4A is a top view of the head cover, and FIG. 4B is a side view of the head cover.
In the handpiece H of the present invention, the side provided with the head 70 is referred to as “front”, and the side to which the motor unit M is connected is referred to as “rear”.

  Referring to FIGS. 1 and 2, the dental handpiece H includes a head 70 and a grip 10. The outer shell of the head 70 and the grip 10 is formed of a metal such as a titanium alloy or an aluminum alloy. The head 70 constitutes the tip portion of the handpiece H, and the treatment tool T is detachably attached. Further, the head 70 is covered by a head cover 100 described later.

The grip 10 is configured of a cylindrical casing 20. At the rear end of the casing 20, a motor unit M, which is a drive source, is connected. The casing 20 is composed of a front casing 21 and a rear casing 22.
In the present embodiment, the front casing 21 and the rear casing 22 are connected at a predetermined inclination angle. That is, the handpiece H is a so-called contra-angle handpiece having a shape bent from the position where the front casing 21 and the rear casing 22 are connected.

The casing 20 may be a straight hand piece in which the front casing 21 and the rear casing 22 are linearly connected. In addition, the casing 2 may be configured by a casing in which the front casing 21 and the rear casing 22 are integrated.
And the grip 10 comprised by the outer surface of the cylindrical casing 20 in this way forms the site | part which a user holds.

Referring to FIG. 2, a bearing 40 is fixed in the rear casing 22. The first rotating shaft 30 is rotatably supported by the bearing 40. At the rear end of the first rotary shaft 30, in the state where the motor unit M is connected to the rear end of the casing 20, a connecting portion 31 engaged with the output shaft J of the motor is provided.
On the other hand, a first gear 32 is provided at the front end of the first rotation shaft 3. The rotation of the output shaft J of the motor is transmitted through the connection portion 31 and the first gear 32 rotates.

A jacket 80 is fixedly provided in the front casing 21. The jacket 80 extends from the head 70 toward the first gear 32. The jacket 80 is a hollow cylindrical member, and includes a shaft through hole 81 through which the second rotation shaft 90 passes, and bearing housing portions 82 and 83.
The jacket 80 is fixed by being pressed against the inner wall of the front casing 2F. That is, the jacket 80 is press-fit into the inside of the front casing 2F. The jacket 80 is inserted from the rear end of the front casing 21 with the second rotation shaft 90 attached.

Next, the second rotation shaft 90 is rotatably supported in the front casing 21 via the jacket 80. The second rotation shaft 90 is rotatably supported by bearings 50 provided in the shaft accommodation portions 82 and 83 inside the jacket 80. Further, the second rotation shaft 90 penetrates the jacket 80.
In the second rotation shaft 90, a second gear 91 is formed in a portion protruding from the rear end side of the jacket 80, and a third gear 92 is formed in a portion protruding from the front end side.

The rotation of the first rotation shaft 30 is transmitted to the second rotation shaft 90 by meshing the second gear 91 of the second rotation shaft 90 with the first gear 32.
In the case of the present embodiment, in the gear train (first gear train) including the first gear 32 and the second gear 91, the second gear 91 is in contact with the first gear 32. That is, the second gear 91 has a smaller number of teeth than the first gear 32.
Thus, the second rotation shaft 9 is accelerated more than the first rotation shaft 3 by meshing the first gear 32 and the second gear 91 having a smaller number of teeth than the first gear 32. That is, the rotation speed of the second rotation shaft 9 is increased compared to the first rotation shaft 3, and the rotation speed is increased.

  Next, the third gear 92 of the second rotating shaft 90 meshes with a fourth gear 74 provided on the head 70 described later to transmit the rotation of the second rotating shaft 90 to the tool holder 73 of the head 70. . Thus, the handpiece H transmits the driving force of the motor (output shaft) to the head 70 via the first rotating shaft 30 and the second rotating shaft 90 to rotationally drive the treatment tool T.

Next, the head 70 will be described with reference to FIGS. The portions shown by dotted lines in FIG. 3 indicate the positions of the upper bearing 75 and the lower bearing 76 provided inside the head 70.
The outer shell of the head 7 has a tube portion 71 and a neck portion 72. The cylindrical portion 71 has a shape that narrows downward.
In the cylindrical portion 71, an upper opening 71a and a lower opening 71b are opened. The neck portion 72 is a cylindrical portion that integrally rises rearward from the side surface of the cylindrical portion 71, and a side opening 72a is formed.

And the head 7 is equipped with the tool holder 73 inside. The treatment tool T is detachably attached to the tool holder 73.
A fourth gear 74 is formed around the tool holder 73. The tool holder 73 is rotatably supported in the vertical direction by an upper bearing 75 and a lower bearing 76 respectively provided on the upper side and the lower side inside the head 7.

  The upper bearing 75 and the lower bearing 76 have an inner ring and an outer ring, and a ball bearing sandwiched between the inner ring and the outer ring, and has an annular shape. The outer ring is fixed in the head 70. The inner ring is rotatable relative to the outer ring by a ball bearing. The tool holder 73 is held by the opening of the inner ring.

  The upper bearing 75 is located above the side opening 72a. The lower bearing 76 is located below the side opening 72a. Further, the upper bearing 75 has a positional relationship opposed to the stepped portion 72c which is a portion from the edge of the upper opening 71a to the rising portion 72b of the neck portion 72. In other words, with reference to the rotational axis of the tool holder 73, the step 72c is located axially outside the upper bearing 75.

In addition, the treatment tool T held by the tool holder 73 is in a state of protruding to the outside of the head 70 downward from the lower opening 71 b. The upper opening 71 a is provided with a holding release button 77 for removing the treatment tool T from the tool holder 73. The user can attach and detach the treatment tool T from the tool holder 73 by pressing the holding release button 77 downward.
The head 70 is fixed to the front casing 21 by the neck portion 72 coming into the front casing 21 from the front opening of the front casing 21. In this state, the second rotation shaft 90 is configured to enter the inside of the head 70 from the side opening 72a.

Then, the fourth gear 74 meshes with the third gear 92 that has entered the inside of the head 7 to form a second gear train. Thus, the rotation of the second rotation shaft 90 is transmitted to the tool holder 73.
In the present embodiment, in the second gear train including the third gear 92 and the fourth gear 74, the number of teeth of the fourth gear 74 is set smaller than that of the third gear 92. Therefore, the tool rotating body 72 in which the fourth gear 74 is formed is rotated at a higher speed than the second rotating shaft 90.
By configuring each part as described above, the speed increasing type handpiece H in which the treatment tool T rotates at a rotational speed higher than that of the motor (rotates faster than the rotational speed of the motor) is configured.

Next, the head cover 100, which is an essential part of the present invention, will be described.
Referring to FIGS. 1 to 4, the head cover 100 is a member disposed on the front end side of the handpiece and covering the outside of the head 70. The head cover 100 has a cylindrical protective portion 101 in which a region facing rearward is cut out (cut), and a pair of left and right holding portions 102 extending rearward from an end of the protective portion 101. The protective portion 101 is in the shape of a letter "C" when viewed from above.
When the protective portion 101 is viewed from above, the inner diameter R1 of the protective portion 101 is larger than the diameter R2 of the cylindrical portion of the head (R1> R2).

In the head cover 100, the protection portion 101 has a spring property. In the case of the present embodiment, the left and right holding portions 102 are opened apart in the left-right direction, respectively, and if the opening force is not applied, there is a characteristic that the original shape is restored. The position where the holding unit 102 is connected to the protection unit 101 is an end of the protection unit 101 in the case of the present embodiment, but may be a position shifted from this end.
In the head cover 100, a region facing the rear of the protection portion 101 is cut out. And it is possible to extend the holding part 102 which pinches this notched part from the left and right in the direction which leaves in the left-right direction. When the application of the spreading force is stopped, the head cover 100 may return to the original shape by the elastic force of the protective portion 101.

  That is, the notched portions of the head cover 100 may be partially connected without completely separating, and even if the end of the protective portion 101 is in contact, it may be separated left and right. In the state of the original shape of the head cover 100, the distance d1 between the left and right holding parts 102 facing each other is configured to be smaller by the width d2 in the left-right direction of the handpiece (d2> d1).

Further, the size of the protective portion 101 in the vertical direction is configured to be equal to or larger than the height L from the upper surface of the upper bearing 75 provided on the head 70 to the lower surface of the lower bearing 76.
In addition, the shapes of the facing portions of the left and right holding portions 102 are respectively configured in accordance with the shapes of the left side and the right side of the front casing 21 close to the head 70.

Such a head cover 100 is made of a material having a thermal conductivity lower than that of metal. In addition, since the head cover 100 may be used in a disposable form for each patient used, an inexpensive material, such as a synthetic resin, which can be relatively easily molded, is used.
In addition, in the case of the head cover 100 which is used after sterilization every time it is used without being disposable, the synthetic resin used is PEEK (polyether ether ketone resin), PEI (polyether imide resin) or PPSU (polyphenyl sulfone). A heat resistant and alkali resistant material such as a resin) is used. By using such a material, it is possible to configure the head cover 100 that can withstand reprocessing such as sterilization, hot water cleaning, and disinfection.

The head cover 100 described above is then attached to the handpiece H as follows.
A force is applied to open the left and right holding portions 102 of the head cover 100, and the handpiece H is covered from above. At this time, the head 70 is positioned inside the protective portion 101 of the head cover 100. Then, the holding portion 102 opened to the left and right is closed by an elastic force that tends to return to the original shape of the head cover 100.

Here, the original shape of the head cover 100 is configured such that the distance d1 between the left and right holding parts 102 facing each other is reduced by the width d2 in the left-right direction of the handpiece (d2> d1). As a result, the left and right holding portions 102 sandwich a portion from the neck portion 72 of the handpiece H to the side surface of the front casing 21, and the head cover 100 is attached to the handpiece H.
When the protective portion 101 of the head cover 100 is viewed from above, the diameter R1 of the protective portion 101 is larger than the diameter R2 of the head 70 (R1> R2). Thus, a gap ΔM is formed between the protective portion 101 and the head 70.

Thus, when the head cover 100 is attached to the handpiece H, the protective portion 101 covers the periphery of the head 70, and a gap ΔM is formed between the protective portion 101 (head cover 100) and the head 70. The gap M communicates with the space outside the head cover 100.
That is, the gap ΔM is a space in which the heat in the head 70 can be dissipated from the surface of the head. Thus, a space for cooling the head 70 is secured.

By configuring each part as described above, it is possible to prevent the head 70 from being directly touched by the human body and to configure the head cover 100 that does not prevent the cooling of the head 70.
In particular, since the head cover 100 of the present embodiment supports the head cover 100 on the side surface of the handpiece H, there is nothing in the space formed between the head cover 100 and the head 70 to block the air flowing in this space.

Further, the size of the protective portion 101 in the vertical direction is configured to be equal to or larger than the height L from the upper surface of the upper bearing 75 provided on the head 70 to the lower surface of the lower bearing 76. The head cover 100 can be covered by the head cover 100 which is heated by the heat generation.
From the above, according to the head cover 100 of the present embodiment, it is possible to prevent the high temperature portion of the head 70 from directly touching the human body and secure a space for cooling that allows the head 70 to dissipate heat from the surface. Can.

In the present embodiment, the holding release button 77 which is the upper portion of the head 70 is not covered by the head cover 100, but the head cover 100 may cover the upper side of the holding release button 77. .
With such a configuration, even if the holding and releasing button 77 becomes hot due to the abnormal temperature rise of the head 70, it is possible to prevent the holding and releasing button 77 from directly touching the human body.

In particular, by configuring the portion of the head cover 100 covering the holding and releasing button 77 in a flexible form, the holding and releasing button 77 can be pressed even in a state where the head cover 100 is attached.
Further, an opening communicating with the gap ΔM may be appropriately provided on the top surface of the head cover 100. With this configuration, air inside the gap ΔM can be easily discharged to the outside of the head cover 100 through this opening.

Second Embodiment
Second Embodiment A second embodiment will now be described with reference to FIGS.
FIG. 5 is a view showing the hand piece according to the present embodiment, and shows (a) a top view of the hand piece, and (b) a bottom view of the hand piece. FIG. 6 shows (a) a top view of the head cover and (b) a side view of the head cover according to the present embodiment. FIG. 7 shows a cross-sectional view of only the head cover and the handpiece in the YY position shown in FIG. 5 (a). Description of the same configuration as that of the first embodiment will be omitted.

On the inner surface of the protective portion 101 of the head cover 100, a protrusion 103 for supporting the protective portion 101 with respect to the head 70 is provided. The protrusion 103 is formed to protrude toward the inside of the protective portion 101. That is, it protrudes toward the center of the cylinder which is the shape of the protection part 101.
Further, the three projections 103 are provided in the protection portion 101 so that the intervals between the three projections 103 are the same. That is, the protrusions 103 are equally spaced at an interval of approximately 120 degrees when viewed from the center of the protection portion 101.

  In the state where the head cover 100 described above is attached to the handpiece H, the projection 103 supports the head cover 100 on the outer peripheral surface of the head 70 at three points. Thereby, the protrusion 103 forms a gap ΔM between the protective portion 101 and the head 70. That is, the projection 103 forms a gap between the protective portion 101 and the head 70 and serves as a gap holder.

In addition, since the projections 103 are uniformly arranged at intervals of 120 degrees from the center of the protective portion 101 and the surface of the head 70 is cylindrical, the center of the protective portion 101 can be aligned with the position of the treatment tool T.
That is, by supporting the protective portion 101 at three points with respect to the outer peripheral surface of the head 70, the center of the portion covering the head of the head cover and the treatment tool T in a state where the number of projections blocking the gap between both parts is the minimum. It can be easily configured to match the position of.

  By configuring each part in this manner, the user can make the positional relationship (distance relationship) between the head cover 100 and the treatment tool T approximately the same regardless of which direction the head 70 is viewed in use. Therefore, when the user brings the treatment tool T into contact with the treatment site while visually observing, the sense of distance between the head cover 100 and the treatment tool T can be equal from any direction.

The shape of the projection 103 may be a rib having a predetermined length. For example, it may have a rib-like shape extending in the vertical direction. By forming the projections 103 in a strip shape, the strength of the head cover 100 can be strengthened. The rib having a predetermined length for forming the protrusion 103 may be provided not only in the vertical direction, but also in the circumferential direction of the protective portion 101 or in a spiral shape.
The protrusion 103 may form a gap between the head 70 and the head cover 100, and the air in the gap may be out of the gap.

Third Embodiment
Third Embodiment A third embodiment will now be described with reference to FIGS.
FIG. 8 is a side view of the hand piece according to the third embodiment, showing a state in which the head cover is discolored in response to high temperature. FIG. 9 is a partial cross-sectional view of the hand piece shown in FIG. The cross-sectional position in FIG. 9 is the left and right center position of the handpiece. Further, a portion shown by a dotted line in FIG. 9 shows an upper bearing 75 and a lower bearing 76 located inside the head 70. Description of the same configuration as that of the first embodiment will be omitted.

  Referring to FIG. 8, head cover 100 is made of a material including a temperature indicator. A temperature indicator is a material that contains a special pigment that changes color when it reaches a certain temperature. In the case of this embodiment, a temperature indicator having a characteristic that the color changes at about 40 degrees is used. In addition, this temperature-indicating material is a reversible material that changes color in the high temperature state and then returns to the original color when the temperature decreases.

Referring to FIG. 9, a first protrusion 104 and a second protrusion 105 are provided on the inner surface of the protective portion 101 of the head cover 100. The first protrusion 104 is located above the protection unit 101. The second protrusion 105 is located below the protection unit 101.
When the head cover 100 is attached to the handpiece, the first projection 104 is located radially outside the upper bearing 75 and is in contact with the surface of the head 70. Further, the second protrusion 105 is located radially outside the lower bearing 76 and is in contact with the surface of the head 70.
The first protrusion 104 and the second protrusion 105 form a gap ΔM between the head 70 and the head cover 100. The first protrusion 104 and the second protrusion 105 are gap holders.

By configuring the head cover 100 as described above and attaching it to the handpiece, it is possible to prevent the high temperature portion of the head 70 from directly touching the human body and a space for cooling that allows the head 70 to dissipate heat from the surface. Can be secured.
Furthermore, as shown in FIG. 8, the head cover 100 is made of a material containing a temperature indicator, so when the head 70 becomes high temperature, it is discolored by the heat (shaded portion C in the figure). Thereby, the user can visually grasp that the head 70 has become hot.

In particular, the first projection 104 and the second projection 105 for supporting the head cover 100 with respect to the head 70 are respectively located on the surface of the head 70 located radially of the upper bearing 75 and the head 70 located radially on the lower bearing 76. In contact with the surface of
The head 70 has a high temperature from a portion near the internal bearings 75 and 76. That is, the portion of the head located at the radial position of the bearing is heated to a high temperature. Therefore, by bringing the projections 104 and 105 into contact with the portions, the temperature of the head cover 100 is increased by heat conduction from the head 70, and the color tends to be discolored.
As a result, the user can easily grasp that the head 70 is in a high temperature state from the discoloration of the head cover 100.

Similarly, the head cover 100 may be configured to be in contact with the step portion 72c formed at a portion from the edge of the upper opening 71a to the rising portion 72b of the neck portion 72. The stepped portion 72 c and the periphery thereof are located axially outside the upper bearing 75.
Therefore, when the upper bearing 75 becomes hot, the upper surface of the head cover 100 is likely to be discolored due to the heat. Thus, the user can easily grasp that the head 70 has become hot. In particular, since this position is the upper surface of the head cover 100, the user is likely to notice the color change of the head cover 100 during work.

  In addition, the temperature indicator constituting the head cover 100 according to the present embodiment is a reversible material that returns to its original color when the temperature drops after it is discolored in a high temperature state. Thus, even if the head cover 100 is sterilized at a high temperature by an autoclave or the like, it can be used again as a detection means of the temperature state of the head 70.

The shapes of the first protrusion 104 and the second protrusion 105 may be a shape having a width extending in the circumferential direction of the protective portion 101. And, by arranging the projections 104 and 105 so as to surround the outside of the bearings 75 and 76, the contact area between the projections 104 and 105 and the surface of the head 70 can be increased.
As a result, the area of contact between the head cover 100 and the head 70 is increased, so that the head cover 100 can be easily influenced by the temperature of the head 70. Therefore, it becomes easy to change the color of the head cover 100 according to the temperature of the head 70, and it is possible to visually grasp that the head 70 has become high temperature.

In the present embodiment, although the case where the temperature indicator is used as the material of the head cover 100 has been described, the material including the temperature indicator may be provided on the surface of the head cover 100 instead of including the temperature indicator in the material of the head cover 100. Good. For example, a tape containing a temperature indicator may be attached to the head cover 100.
When a tape containing a temperature indicator is provided on the head cover 100, it may be provided at a position susceptible to heat when the head 70 becomes hot. For example, it may be provided at a position opposite to the projections 104 and 105 in contact with the head 70.

  As described above, the invention described in each of the embodiments is particularly effective for a speed increasing handpiece which transmits the rotational driving force of the motor to the treatment tool T at a speed higher than the rotational speed of the motor. This is because as the number of rotations increases, heat generation is likely to occur in the upper bearing 75 or the lower bearing 76, and the head is likely to be hot.

  In addition to this, even with a reduction handpiece in which the number of teeth of connected gears is increased as the gear is closer to the head and the rotation speed of the treatment tool is smaller than the rotation of the motor, heat may be generated in the upper bearing 75 or lower bearing 76 The invention described in each embodiment is effective. In addition, even a constant velocity handpiece in which the rotation of the motor and the number of rotations of the treatment tool are the same is effective for the same reason.

T treatment tool M motor unit J output shaft H handpiece 10 grip 20 casing 21 front casing 22 rear casing 30 first rotary shaft 31 connecting portion 32 first gear 40 bearing 50 bearing 70 head 71 cylinder 71a upper opening 71b lower opening 72 neck portion 72a side opening 72c step portion 73 tool holder 74 fourth gear 75 upper bearing 76 lower bearing 77 holding release button 80 jacket 81 shaft through hole 82 bearing accommodation portion 83 bearing accommodation portion 90 second rotation shaft 91 second gear 92 Third gear 100 Head cover 101 Protective portion 102 Holding portion 103 Projection 104 First projection 105 Second projection

Claims (4)

A head cover for covering the head of a handpiece comprising a casing constituting a grip and having a motor unit connected at the rear end thereof and a head fixed to the front side of the casing to which a treatment tool is detachably attached.
The head includes a tool holder for holding the treatment tool inside, and an upper bearing and a lower bearing for rotatably supporting the tool holder, and the treatment tool is directed downward to the outside of the head It stands out,
The head cover, in a state of being attached to the handpiece, has a cylindrical protective portion in which a region facing rearward is notched, and sandwiches the notched portion from the left and right and extends rearward from the protective portion It has a pair of left and right holding parts, and has elasticity to try to return to the original shape when the pair of the holding parts are spread apart in the left and right direction,
When the protective portion is viewed from above, the inner diameter of the protective portion is larger than the diameter of the cylindrical shape of the head, and the vertical size of the protective portion is the upper surface of the upper bearing. Is the same as or larger than the height from the lower bearing to the lower surface of the lower bearing,
In a state where the head cover is attached to the hand piece to cover the head, the head cover has a gap communicating with a space outside the head cover with the head inside the protective portion. , head cover, characterized in that said head is as well as the position, the holding portions of the pair is attached to the handpiece at a write Mukoto sandwiching side of the casing from the horizontal direction by the elastic.   The head cover according to claim 1, wherein the head cover has a gap holding member that keeps a gap with the head in a state of being attached to the hand piece.   The head cover according to claim 1, wherein the head cover has a temperature indicator.   A medical handpiece comprising the head cover according to any one of claims 1 to 3.

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