Patent Description:
In a related art, there has been known a robotic surgical instrument including a support body and a shaft.

<CIT> discloses a medical treatment tool (a robotic surgical instrument) including a support body and a shaft. The medical treatment tool includes a wrist member and an end effector. The support body is attached to the shaft. The wrist member is rotatably attached to the support body. The end effector is rotatably attached to the wrist member.

The medical treatment tool disclosed in <CIT> is configured to, based on an operation by a surgeon or the like, rotate the wrist member attached to the support body and the end effector attached to the wrist member, so as to perform an endoscope surgery on a treatment target such as a human being, an animal, or the like.

<CIT> discloses sealing assemblies and methods for sealing a surgical instrument having an internal drive shaft subject to lateral displacement. A sealing assembly including a rigid portion shaped to interface with an instrument shaft of the surgical instrument. A laterally oriented slot is open at a radially perimeter location and configured to receive an o-ring seal via the perimeter location. Apertures are disposed on opposing sides of the slot and open to the slot. The apertures are configured to receive the drive shaft there through and are larger than the drive shaft to accommodate lateral displacement of the drive shaft. The slot includes opposing internal sides spaced to interface with opposed axial surfaces of the o-ring seal. The seal inhibits axial transmission of an insufflated gas and/or bodily fluids while accommodating lateral displacement of the drive shaft.

<CIT> discloses a flexible forceps device comprises a distal end to be inserted into a patient, a proximal end to remain outside the patient and a flexible, elongated body extending between the ends. The flexible body has at least one lumen and may have a smooth, sealed external surface. An effector assembly is attached to the distal end and includes a support piece and at least one movable element. A control assembly is attached to the proximal end and includes a push-pull mechanism. A coaxial actuating assembly extending through the lumen of the flexible body consists of a flexible tube having a lumen, with a control wire slidably disposed within the lumen of the tube. The tube provides a flexible, yet relatively incompressible column support between the effector assembly and control assembly. The proximal end of the control wire is attached to the push-pull mechanism and the distal end is linked to the movable elements, whereby operation of the control assembly moves the movable elements relative to the support piece. The coaxial actuating assembly undergoes a relatively small change in bending stiffness when the control wire is pushed or pulled, resulting in little displacement of the effector assembly relative to the control assembly during operation of the control assembly.

When performing the endoscope surgery, a gas filled in a body cavity of the treatment target may need to be prevented from leaking to the outside of the body from the treatment portion through the shaft. Thus, it may be necessary to arrange a seal member in the support body in such a manner that the seal member is pressed and compressed by the shaft.

However, if the size of the support body is small, the size of the seal member will also be small according to the size of the support body. This makes the surface of the seal member that is to be pressed by the shaft smaller, and may make it difficult to sufficiently press the seal member by the shaft. Therefore, even if the size of the support body is small, it may be desired that the seal member is sufficiently compressed by the shaft so as to more reliably seal the support body.

An object of invention is to provide a robotic surgical instrument capable of sufficiently compressing a seal member by a shaft so as to more reliably seal a support body.

The problem is solved by the teachings of the independent claims.

An aspect of the disclosure is a surgical instrument to be attached to a robot arm. The surgical instrument includes: an end effector; an end effector support body that supports the end effector to be rotatable about a first axis with respect to the end effector support body; a support body that supports the end effector support body to rotatable about a second axis with respect to the support body; a shaft to which the support body is connected; a seal member arranged in the support body; and a pressing member including a pressing surface in contact with and pressing a surface of the seal member on a side of the shaft, wherein the pressing member is pressed by the shaft.

Another aspect of the disclosure is a method of assembling a surgical instrument, wherein the surgical instrument includes: an end effector; a first support body that supports the end effector to be rotatable about a first axis; a second support body that supports the first support body to rotatable about a second axis; and a shaft to which the second support body is connected.

The method of assembling the surgical instrument includes: disposing a seal member in the second support body; moving a pressing member in an axial direction of the shaft along a cutout of the second support body; and pressing and compressing the seal member against the second support body by moving the pressing member in the axial direction of the shaft.

According to the invention, even when the size of the support body is small, it is possible to sufficiently compress the seal member by the shaft so as to more reliably seal the support body.

Descriptions are provided hereinbelow for one or more embodiments based on the drawings. In the respective drawings referenced herein, the same constituents are designated by the same reference numerals and duplicate explanation concerning the same constituents is omitted. All of the drawings are provided to illustrate the respective examples only. The invention is defined in appended independent claims <NUM> and <NUM>. Further embodiments are defined in appended dependent claims.

The configuration of a robotic surgical system <NUM> is described with reference to <FIG> and <FIG>.

As illustrated in <FIG>, the robotic surgical system <NUM> includes a remote control apparatus <NUM> and a patient-side apparatus <NUM>. The remote control apparatus <NUM> is provided to remotely control medical equipment provided to the patient-side apparatus <NUM>. When an operator O such as a surgeon or the like inputs an action mode instruction to be executed by the patient-side apparatus <NUM>, to the remote control apparatus <NUM>, the remote control apparatus <NUM> transmits the action mode instruction to the patient-side apparatus <NUM>. In response to the action mode instruction transmitted from the remote control apparatus <NUM>, the patient-side apparatus <NUM> operates medical equipment, including surgical instruments <NUM> attached to robot arms <NUM> and an endoscope <NUM> attached to a robot arm <NUM>. This allows for minimally invasive surgery.

The patient-side apparatus <NUM> is positioned beside an operation table <NUM> on which the patient P is laid. The patient-side apparatus <NUM> constitutes an interface to perform a surgery for a patient P in response to an input from the remote control apparatus <NUM>. The patient-side apparatus <NUM> includes plural robot arms <NUM>, a robot arm <NUM>, a platform <NUM>, a positioner <NUM>, and a controller (not illustrated).

Each of the plural robot arms <NUM> includes plural joints. Each joint of the robot arm <NUM> includes a driver (not illustrated) provided with a servo-motor and a position detector such as an encoder. The robot arms <NUM> are configured so that the medical equipment attached to each robot arm <NUM> is controlled by a driving signal given through the controller and performs a desired movement. Note that the robot arm <NUM> has a configuration same as the robot arm <NUM>.

The surgical instruments <NUM> as the medical equipment are detachably attached to the distal end portions of the robot arms <NUM>. In surgeries using the patient-side apparatus <NUM>, the robot arms <NUM> introduce the surgical instruments <NUM> into the body of the patient P through a cannula (trocar) placed on the body surface of the patient P.

One of the surgical instruments <NUM> is a monopolar scissors and includes: a housing <NUM> (see <FIG>), which is attached to the robot arm <NUM>; an elongated shaft <NUM> (see <FIG>); and an end effector <NUM> (see <FIG>), which is provided at the distal end portion of the shaft <NUM>. Note that the surgical instrument <NUM> may be a surgical instrument other than the monopolar scissors. For example, the surgical instrument <NUM> may be a surgical instrument <NUM> including an end effector <NUM> such as grasping forceps, scissors, a hook, a high-frequency knife, a snare wire, a clamp, or a stapler, for example. The end effector <NUM> of the surgical instrument <NUM> is then located near the surgery site (treatment site).

To the distal end of the robot arm <NUM>, the endoscope <NUM> as medical equipment is detachably attached. The endoscope <NUM> captures an image within the body cavity of the patient P. The captured image is outputted to the remote control apparatus <NUM>. The endoscope <NUM> is a 3D endoscope capable of capturing a three-dimensional image or a 2D endoscope. In surgeries using the patient-side apparatus <NUM>, the robot arm <NUM> introduces the endoscope <NUM> into the body of the patient P through a trocar placed on the body surface of the patient P. The endoscope <NUM> is then located near the surgery site.

The platform <NUM> commonly supports the robot arms <NUM> and the robot arm <NUM>. The positioner <NUM> is placed on the floor of an operation room and supports the platform <NUM>. The positioner <NUM> includes a column 24a including an elevating shaft adjustable in the vertical direction and a base 24b including wheels and thus being movable on the floor surface.

The remote control apparatus <NUM> constitutes the interface with the operator O. The remote control apparatus <NUM> is an apparatus that allows the operator O to operate the surgical instruments <NUM> attached to the robot arms <NUM> and the endoscope <NUM> attached to the robot arm <NUM>. Specifically, the remote control apparatus <NUM> is configured to transmit action mode instructions which are inputted by the operator O and are to be executed by the surgical instruments <NUM> and endoscope <NUM>, to the patient-side apparatus <NUM> through the controller. The remote control apparatus <NUM> is installed beside the operation table <NUM> so that the operator O can see the condition of the patient P very well while operating the remote control apparatus <NUM>, for example. The remote control apparatus <NUM> may be configured to transmit action mode instructions wirelessly and installed in a room different from the operation room where the operation table <NUM> is installed.

The action modes to be executed by the surgical instruments <NUM> include modes of actions to be taken by each surgical instrument <NUM> (a series of positions and postures) and actions to be executed by the function of each surgical instrument <NUM>. When the surgical instrument <NUM> is a pair of grasping forceps, for example, the action modes to be executed by the surgical instrument <NUM> include roll and pitch positions of the wrist of the end effector <NUM> and actions to open and close the jaws. When the surgical instrument <NUM> is a high-frequency knife, the action modes to be executed by the surgical instrument <NUM> may include vibration of the high-frequency knife, specifically, supply of current to the high-frequency knife. When the surgical instrument <NUM> is a snare wire, the action modes to be executed by the surgical instrument <NUM> may include a capturing action and an action to release the captured object. Further the action modes may include an action to supply current to a bipolar or monopolar instrument to burn off the surgery site.

The action modes to be executed by the endoscope <NUM> include, for example, an action mode to move the position and posture of the distal end of the endoscope <NUM> and an action mode to set the zoom magnification, for example.

As illustrated in <FIG> and <FIG>, the remote control apparatus <NUM> includes operation handles <NUM>, an operation pedal section <NUM>, a display part <NUM>, and a control apparatus <NUM>.

The operation handles <NUM> are provided in order to remotely operate medical equipment (surgical instruments <NUM> and the endoscope <NUM>) attached to the robot arms <NUM> and <NUM>. Specifically, the operation handles <NUM> accept operations by the operator O for operating the medical equipment. The operation handles <NUM> include two operation handles <NUM> arranged side by side in the horizontal direction. One of the two operation handles <NUM> is operated by the right hand of the operator O while the other operation handle <NUM> is operated by the left hand of the operator O.

The operation handles <NUM> extend from the rear side of the remote control apparatus <NUM> toward the front side. The operation handles <NUM> are configured to move in a predetermined three-dimensional operation region. Specifically, the operation handles <NUM> are configured so as to move up and down, right and left, and forward and rearward.

The remote control apparatus <NUM> and patient-side apparatus <NUM> constitute a master-slave system in terms of controlling movement of the robot arms <NUM> and robot arm <NUM>. The operation handles <NUM> constitute an operating part on the master side in the master-slave system. The robot arms <NUM> and robot arm <NUM> holding medical equipment constitute an operating section on the slave side. When the operator O operates the operation handles <NUM>, the movement of the robot arms <NUM> or <NUM> is controlled so that the distal end portions (the end effectors <NUM> of the surgical instruments <NUM>) of the robot arms <NUM> or the distal end portion (the endoscope <NUM>) of the robot arm <NUM> moves following the movement of the operation handles <NUM>. In this way, the operations of the robot arms <NUM> and the robot arm <NUM> are controlled.

The patient-side apparatus <NUM> controls the movement of the robot arms <NUM> in accordance with the set motion scaling ratio. When the motion scaling ratio is set to <NUM>/<NUM>, for example, the end effectors <NUM> of the surgical instruments <NUM> move <NUM>/<NUM> of the movement distance of the operation handles <NUM>. This allows for precise fine surgery.

The operation pedal section <NUM> includes plural pedals to execute medical equipment-related functions. The plural pedals include a coagulation pedal, a cutting pedal, a camera pedal, and a clutch pedal. The plural pedals are operated by a foot of the operator O.

The coagulation pedal enables the surgical instrument <NUM> to coagulate a surgery site. Specifically, when the coagulation pedal is operated, voltage for coagulation is applied to the surgical instrument <NUM> to coagulate a surgery site. The cutting pedal enables the surgical instrument <NUM> to cut a surgery site. Specifically, the cutting pedal is operated to apply voltage for cutting to the surgical instrument <NUM> and cut a surgery site.

The camera pedal is used to control the position and orientation of the endoscope <NUM> that captures images within the body cavity. Specifically, the camera pedal enables operation of the endoscope <NUM> by the operation handles <NUM>. The position and orientation of the endoscope <NUM> are controllable by the operation handles <NUM> while the camera pedal is being pressed. The endoscope <NUM> is controlled by using both of the right and left operation handles <NUM>, for example. Specifically, when the operator O rotates the right and left operation handles <NUM> about the middle point between the right and left operation handles <NUM>, the endoscope <NUM> is rotated. When the operator O presses the right and left operation handles <NUM> together, the endoscope <NUM> goes forward into the body cavity. When the operator O pulls the right and left operation handles <NUM> together, the endoscope <NUM> goes back. When the operator O moves the right and left operation handles <NUM> together up, down, right, or left, the endoscope <NUM> moves up, down, right, or left, respectively.

The clutch pedal is used to temporarily disconnect operation-related connection between the operation handles <NUM> and the robot arms <NUM> and <NUM> to stop movement of the surgical instruments <NUM>. Specifically, when the clutch pedal is being pressed, the robot arms <NUM> and <NUM> of the patient-side apparatus <NUM> do not work even if the operation handles <NUM> are operated. For example, when the operation handles <NUM> are operated and moved to the edge of the range of movement, the operator O operates the clutch pedal to temporarily disconnect the operation-related connection and then returns the operation handles <NUM> to the center of the range of movement. When the operator O stops operating the clutch pedal, the operation handles <NUM> are again connected to the robot arms <NUM> and <NUM>. The operator O restarts the operation for the operation handles <NUM> around the center thereof.

The display part <NUM> or a display is configured to display images captured by the endoscope <NUM>. The display part <NUM> includes a scope type display section or a non-scope type display section. The scope type display section is a display section that the operator O looks into. The non-scope type display section is a display section like an open-type display section that includes a flat screen and the operator O is able to see without looking into, such as normal displays for personal computers.

When the scope type display section is attached, the scope type display section displays 3D images captured by the endoscope <NUM> attached to the robot arm <NUM> of the patient-side apparatus <NUM>. When the non-scope type display section is attached, the non-scope type display section also displays 3D images captured by the endoscope <NUM> provided for the patient-side apparatus <NUM>. The non-scope type display section may display 2D images captured by the endoscope <NUM> provided for the patient-side apparatus.

As illustrated in <FIG>, the control apparatus <NUM> includes a controller <NUM>, a storage <NUM>, and an image controller <NUM>, for example. The controller <NUM> includes a calculator such as a CPU. The storage <NUM> includes a memory, such as a ROM (Read Only Memory) and a RAM (Random Access Memory). The control apparatus <NUM> may be composed of a single controller performing centralized control or may be composed of plural controllers that perform decentralized control in cooperation with each other.

The controller <NUM> determines whether an action mode instruction inputted by the operation handles <NUM> is to be executed by the surgical instruments <NUM> or to be executed by the endoscope <NUM>, depending on the state of the operation pedal section <NUM>. When determining that the action mode instruction inputted by the operation handles <NUM> is to be executed by any one of the surgical instruments <NUM>, the controller <NUM> transmits the action mode instruction to the corresponding robot arm <NUM>. The robot arm <NUM> is thereby driven for controlling movement of the surgical instrument <NUM> attached to the robot arm <NUM>.

When determining that the action mode instruction inputted by the operation handles <NUM> is to be executed by the endoscope <NUM>, the controller <NUM> transmits the action mode instruction to the robot arm <NUM>. The robot arm <NUM> is thereby driven for control of movement of the endoscope <NUM> attached to the robot arm <NUM>.

The storage <NUM> stores control programs corresponding to the types of the surgical instrument <NUM>, for example. The controller <NUM> reads the stored control programs according to the types of the attached surgical instruments <NUM>. The action mode instruction from at least one of the operation handles <NUM> and the operation pedal section <NUM> of the remote control apparatus <NUM> thereby cause the respective surgical instruments <NUM> to perform proper movements.

The image controller <NUM> transmits images acquired by the endoscope <NUM> to the display part <NUM>. The image controller <NUM> performs processing and alternations for the images when needed.

With reference to <FIG>, the configurations of the surgical instrument <NUM>, adaptor <NUM>, drape <NUM>, and robot arm <NUM> are described.

Here, the direction in which the surgical instrument <NUM> (the direction in which the shaft <NUM> extends) is defined as a Y direction, the distal side (the side toward the end effector <NUM>) of the surgical instrument <NUM> along the Y direction is defined as a Y1 direction, and the opposite side of the Y1 direction is defined as a Y2 direction. The direction in which the surgical instrument <NUM> and the adaptor <NUM> are adjacent to each other is defined as a Z direction, the surgical instrument <NUM> side along the Z direction is defined as a Z1 direction, and the opposite side of the Z1 direction is defined as a Z2 direction. Further, the direction orthogonal to the Y direction and the Z direction is referred to as an X direction, one side along the X direction is referred as an X1 direction, and the other side along the X direction is referred to as an X2 direction. The radial direction of the shaft <NUM> is referred to as the D direction, and the circumferential direction of the shaft <NUM> is referred to as the R direction.

As illustrated in <FIG>, the surgical instrument <NUM> is detachably connected to the robot arm <NUM> through the adaptor <NUM>. The adaptor <NUM> is a drape adaptor configured to sandwich a sterile drape <NUM> to cover the robot arm <NUM>, in conjunction with the robot arm <NUM>. That is, the adaptor <NUM> is configured such that the drape <NUM> is attachable to the adaptor <NUM>.

The surgical instrument <NUM> is attached to the Z1 side of the adaptor <NUM>. The adaptor <NUM> is attached to the Z1 side of the robot arm <NUM>.

The robot arm <NUM> is used in the clean area and is thus covered with the drape <NUM>. In operation rooms, clean technique is used in order to prevent surgical incision sites and medical equipment from being contaminated by pathogen, foreign matters, or the like. The clean technique defines a clean area and a contaminated area, which is other than the clean area. The surgery sites are located in the clean area. Members of the surgical team, including the operator O, make sure that only sterile objects are placed in the clean area during surgery and perform sterilization for an object which is to be moved to the clean area from the contaminated area. Similarly, when the assistant, as one of the members of the surgical team including the operator O, place their hands in the contaminated area, the members sterilize their hands before directly touching objects located in the clean area. Instruments used in the clean area are covered with the drape <NUM> sterilized or to be sterilized.

As illustrated in <FIG>, the drape <NUM> includes a body section <NUM> that covers the robot arm <NUM> and an attachment section <NUM> sandwiched between the robot arm <NUM> and the adaptor <NUM>. The body section <NUM> is made of a flexible film member. The flexible film member is made of a resin material, such as thermoplastic polyurethane and polyethylene. The body section <NUM> includes an opening so that the robot arm <NUM> is engaged with the adaptor <NUM>. In the opening of the body section <NUM>, the attachment section <NUM> is provided so as to close the opening. The attachment section <NUM> is made of a resin mold member. The resin mold member is made of a resin member such as polyethylene terephthalate. The attachment section <NUM> is harder (less flexible) than the body section <NUM>. The attachment section <NUM> includes an opening so that the robot arm <NUM> is engaged with the adaptor <NUM>. The opening of the attachment section <NUM> may be provided corresponding to the section where the robot arm <NUM> is engaged with the adaptor <NUM>. The opening of the attachment section <NUM> may include plural openings corresponding to plural sections at which the robot arm <NUM> is engaged with the adaptor <NUM>.

As illustrated in <FIG> and <FIG>, the surgical instrument <NUM> includes the plural (four) driven members 4a. The driven members 4a are provided within the housing <NUM> and are rotatable about the respective rotation axes G extending along the Z axis. The plural driven members 4a are provided to operate (drive) the end effector <NUM>. For example, the driven members 4a are connected to the end effector <NUM> with wires (first elongate element W1 and second elongate element W2 described later) inserted through the shaft <NUM>. With this, rotations of the driven members 4a drive the wires, which operate (drive) the end effector <NUM>. In addition, the driven member 4a is connected to the shaft <NUM> through gears (not illustrated), for example. With this, the shaft <NUM> is rotated with rotation of the driven member 4a, and the end effector <NUM> is rotated with rotation of the shaft <NUM>.

To transmit driving forces from the robot arm <NUM> to the end effector <NUM>, the driven members 4a include engagement projections <NUM>, which are engaged with later-described drive transmission members <NUM> of the adaptor <NUM>. The engagement projection <NUM> is projected from the Z2 side surface of the driven member 4a toward the side of the adaptor <NUM> (the Z2 side). Each of the engagement projections <NUM> has a shape corresponding to the corresponding engagement recess <NUM> (see <FIG>) of the adaptor <NUM> and having projected portions arranged in line. Each of the engagement projections <NUM> has a line-symmetric shape.

As illustrated in <FIG> and <FIG>, the adaptor <NUM> includes a plurality (four) of the drive transmission members <NUM>. The drive transmission members <NUM> are configured to transmit driving forces from the robot arm <NUM> to the driven members 4a of the surgical instrument <NUM>. That is, the drive transmission members <NUM> are provided so as to correspond to the driven members 4a of the surgical instrument <NUM>. The drive transmission members <NUM> are rotatable about the respective rotation axes B, which extend along the Z direction.

As illustrated in <FIG>, each of drive transmission members <NUM> includes the engagement recess <NUM> which is respectively engaged with the engagement projection <NUM> of the corresponding driven member 4a of the surgical instrument <NUM>. The engagement recess <NUM> is located at the surgical instrument <NUM> side (the Z1 side) of the drive transmission member <NUM> and is recessed from the Z1 side surface of the drive transmission member <NUM>, toward the Z2 direction, opposite to the surgical instrument <NUM>. Each of the engagement recesses <NUM> has a line-symmetric shape.

As illustrated in <FIG>, each of the drive transmission members <NUM> includes an engagement recess <NUM>, which is engaged with an engagement projection <NUM> of the corresponding drive part 21b of the robot arm <NUM>. The engagement recess <NUM> is located at the robot arm <NUM> side (the Z2 side) of the drive transmission member <NUM>. The engagement recess <NUM> is recessed from the Z2 side surface of the drive transmission member <NUM>, toward the Z1 direction, opposite to the robot arm <NUM>. The plural drive transmission members <NUM> include substantially the same configuration. Each of the engagement recesses <NUM> has a line-symmetric shape.

As illustrated in <FIG>, the robot arm <NUM> includes the frame 21a and the plural (four) drive parts 21b. Each of the drive parts 21b is attached to the frame 21a of the robot arm <NUM>. The plural drive parts 21b are provided corresponding to the plural (four) drive transmission members <NUM> of the adaptor <NUM>. Each of the drive parts 21b has the same or a similar configuration, and thus only one of the drive parts 21b is described below to avoid redundancy.

Each of the drive parts 21b includes the engagement projection <NUM> and an actuator <NUM>.

The engagement projection <NUM> of each drive part 21b is engaged with the engagement recess <NUM> of the corresponding drive transmission member <NUM> (see <FIG>). Each of the engagement projections <NUM> is projected from the Z1 side surface of the drive part 21b toward the Z1 side (the adaptor <NUM> side). Each of the engagement projections <NUM> has a line-symmetric shape.

The actuator <NUM> includes a motor. The actuator <NUM> is configured to drive the engagement projection <NUM> to rotate about the rotational axis A extending in the Z direction. Thereby, the drive transmission member <NUM> of the adaptor <NUM> engaged with the engagement projection <NUM> can be rotated about the rotational axis B extending in the Z direction, and the driven member 4a of the surgical instrument <NUM> engaged with the drive transmission member <NUM> can be rotated about the rotational axis G. Note that the rotational axis A, the rotational axis B, and the rotational axis G are coaxially arranged.

With reference to FIGS. <NUM> to <NUM>, the surgical instrument <NUM> is described in detail. The surgical instrument <NUM> according to an embodiment is configured to prevent gas (such as carbon dioxide, etc.) filled in a body cavity of the patient for the surgery in an abdominal cavity or the like from leaking out of a treatment portion where the surgical instrument <NUM> is inserted. That is, the surgical instrument <NUM> is configured to prevent the gas filled in the body cavity of the patient from leaking into the surgical instrument <NUM> and thus prevent the gas from passing through the surgical instrument <NUM> to the outside of the body of the patient.

As illustrated in <FIG> and <FIG>, the surgical instrument <NUM> includes the end effector <NUM>, an end effector support body <NUM> serving as a first support body supporting the end effector <NUM> to be rotatable about a first axis A1, a base <NUM> (clevis) serving as a second support body supporting the end effector support body <NUM> to be rotatable about a second axis A2, and the shaft <NUM> connected to the base <NUM>. The surgical instrument <NUM> includes a seal member <NUM>. The seal member <NUM> is provided in the base <NUM> and prevents the gas filled in the body cavity of the patient P from leaking out of the body from the treatment portion via the shaft <NUM>. The surgical instrument <NUM> includes a retainer <NUM> serving as a pressing member (see <FIG>). The retainer <NUM> includes a pressing surface 48a that abuts a surface <NUM> of the seal member <NUM> on the shaft <NUM> side (the Y2 side) and presses the surface <NUM> in the D direction in an area from a center portion to an outer side portion of the surface <NUM>. The base <NUM> is an example of a support body in this disclosure. The retainer <NUM> is an example of a pressing member in this disclosure.

With this, even when the size of the seal member <NUM> is small because the size of the base <NUM> is small, it is possible to sufficiently press the surface <NUM> of the seal member <NUM> on the shaft <NUM> side by the shaft <NUM> via the pressing surface 48a of the retainer <NUM> toward the end effector <NUM> side so as to more reliably compress the seal member <NUM> by the shaft <NUM>. As a result, even when the size of the base <NUM> is small, it is possible to sufficiently compress the seal member <NUM> by the shaft <NUM> toward the end effector <NUM> side so as to more reliably seal the base <NUM>.

Specifically, the end effector <NUM> includes plural (two) end effector members 43a. That is, the plural end effector members 43a are attached to the end effector support body <NUM> such that the plural end effector members 43a are rotatable about the first axis A1 with respect to the end effector support body <NUM>. Each of the end effector members 43a includes a pulley section 43b. Each of the end effector members 43a is configured to change its posture as a second elongate element W2 wound around the pulley section 43b thereof moves. In this example, the end effector <NUM> is a scissors. With this structure, even in a case where the scissors whose base <NUM> is smaller than those of other types of end effectors is used as an end effector <NUM>, the seal member <NUM> can be sufficiently pressed by the shaft <NUM> via the retainer <NUM>. The end effector <NUM> may be an end effector other than a scissors.

The end effector support body <NUM> includes a pulley section 44a, a first pulley group 44b, and a second pulley group 44c. The pulley section 44a is supported by the base <NUM> to be rotatable about the second axis A2 with respect to the base <NUM>. The pulley section 44a includes a pulley groove 144a formed along a circumferential direction of the second axis A2. The end effector support body <NUM> is configured to change its posture as a first elongate element W1 wound around the pulley section 44a thereof moves.

The first pulley group 44b and the second pulley group 44c guide the second elongate elements W2 engaged with the pulley section 43b of the end effector member 43a. The first pulley group 44b is arranged between the second axis A2 and the first axis A1. The second pulley group 44c is arranged on the second axis A2.

Here, the first elongate element W1 and the second elongate elements W2 are composed of a wire or a cable. The wire or the cable is made of a metal such as stainless or tungsten. The number of the first elongate element(s) W1 is set corresponding to the number of the pulley section(s) 44a. In this example, the number of the first elongate element(s) W1 is one. The number of the second elongate element(s) W2 is set corresponding to the number of the end effector members 43a. In this example, the number of the second elongate element(s) W2 is two.

As illustrated in <FIG> and <FIG>, the base <NUM> includes a connection base portion 45a formed with cutouts <NUM> or recesses.

The connection base portion 45a is formed in a substantially cylindrical shape. The connection base portion 45a is connected to the shaft <NUM>. Specifically, an end portion of the shaft <NUM> on the Y1 side is connected to an end portion of the connection base portion 45a on the Y2 side. The connection base portion 45a includes a circumferential wall 45b extending along the R direction and a partition wall <NUM> provided in an end portion of the connection base portion 45a on the side opposite to the shaft <NUM> (an end portion on the Y1 side). The cutouts <NUM> are formed in the circumferential wall 45b. The cutouts <NUM> are recessed from the end of the base <NUM> on the shaft <NUM> side toward the end effector <NUM> side in the Y direction (the axial direction of the shaft <NUM>).

The connection base portion 45a includes a first support portion 145a and a second support portion 145b which rotatably support the end effector support body <NUM>. The first support portion 145a protrudes in the Y1 direction from an end portion of the connection base portion 45a on the Z1 side. The second support portion 145b protrudes in the Y1 direction from an end portion of the connection base portion 45a on the Z2 side.

The connection base portion 45a includes an inner space 45d surrounded by the circumferential wall 45b and the partition wall <NUM>. The inner space 45d of the connection base portion 45a is opened toward the Y2 side.

The partition wall <NUM> includes an end surface 45c on the opposite side of the shaft <NUM> (the Y1 side), communication holes <NUM>, and a through hole <NUM>. The partition wall <NUM> is configured to separate the inner space 45d and the outer space of the connection base portion 45a. The communication holes <NUM> penetrate through the partition wall <NUM> in the Y direction. The communication holes <NUM> connect the inner space 45d of the connection base portion 45a and the outer space of the connection base portion 45a. Here, in the partition wall <NUM>, a communication hole <NUM> located on the X1 side (hereinafter, a first communication hole 453a) and a communication hole <NUM> located on the X2 side (hereinafter, a second communication hole 453b) are formed. That is, the communication holes <NUM> includes the first and second communication holes 453a and 453b. The first communication hole 453a and the second communication hole 453b are formed in a T-like shape as seen in the Y direction. The through hole <NUM> penetrates through the partition wall <NUM> in the Y direction. The through hole <NUM> is formed in a substantially circular shape as seen in the Y direction.

In the through hole <NUM> of the partition wall <NUM>, a cover Cv covering the electric wire E is inserted. The electric wire E is provided for supplying electric energy to the end effector <NUM>. The electric wire E electrically connects the end effector and an electric power supply. Note that the electric wire E may be indirectly connected to the end effector <NUM>. For example, the electric wire may be connected to the end effector <NUM> via the base <NUM>, the end effector support body <NUM>, or the like. The cover Cv covers the electric wire E from the outer side in the D direction.

On an inner surface <NUM> of the circumferential wall 45b, a recessed portion 45e is formed. The recessed portion 45e includes a plurality (six, in this example) of recessed portions 45e on the inner surface <NUM> of the connection base portion 45a. The plurality of recessed portions 45e are arranged side by side in the R direction. Each recessed portion 45e is formed in a shape recessed toward the outer side in the D direction from the inner circumferential surface <NUM> of the connection base portion 45a.

As illustrated in <FIG> and <FIG>, the shaft <NUM> is formed in a cylindrical shape extending along the Y direction. The first elongate element W1, and the second elongate elements W2 are housed in the space inside the shaft <NUM>. The shaft <NUM> includes a projection 42a. The projection 42a extends in the Y direction. The projection 42a projects from the end of the shaft <NUM> on the Y1 side toward the end effector <NUM> side in the Y direction. The projection 42a includes a plurality (two, in this example) of projections 42a arranged along the R direction.

In the space in the shaft <NUM>, a Y2 side portion of the base <NUM> is accommodated. In this state, the end of the shaft <NUM> is in contact with a step portion of the circumferential wall 45b of the base <NUM>. Further, the projections 42a of the shaft <NUM> are inserted in the cutouts <NUM> of the base <NUM>.

As illustrated in <FIG> and <FIG>, the seal member <NUM> is made of an elastomer such as silicone rubber or the like. The seal member <NUM> is configured to be elastically deformable. The seal member <NUM> has a thickness in the Y direction. The seal member <NUM> is compressed at the end of the inner space 45d of the base <NUM> on the Y1 side. The seal member <NUM> is in close contact with the partition wall <NUM> of the base <NUM>.

The seal member <NUM> closes the first communication hole 453a and the second communication hole 453b of the base <NUM>. Further, the seal member <NUM> is configured such that the first elongate element W1 and the second elongate elements W2 are attachable, after the first elongate element W1 is attached to the end effector support body <NUM> and the second elongate elements W2 are attached to the end effector <NUM>.

Specifically, the seal member <NUM> includes a first insertion hole 47a, a second insertion hole 47b, and a slit 47c. In the first insertion hole 47a, the first elongate element W1 is inserted. The first insertion hole 47a penetrates the seal member <NUM> in the Y direction. The first insertion hole 47a includes a plurality (two, in this example) of first insertion holes 47a in the seal member <NUM>. In the second insertion hole 47b, the second elongate element W2 is inserted. The second insertion hole 47b penetrates the seal member <NUM> in the Y direction. The second insertion hole 47b includes a plurality (four, in this example) of second insertion holes 47b in the seal member <NUM>.

The slit 47c extends from an outer circumferential surface 47f of the seal member <NUM> to the first insertion hole 47a or the second insertion hole 47b. That is, the slit 47c includes a plurality (six, in this example) of slits 47c provided in the seal member <NUM> corresponding to the total number of the first insertion holes 47a and the second insertion holes 47b. Each of the slits 47c connects the outer circumferential surface 47f of the seal member <NUM> to the first insertion hole 47a or the second insertion hole 47b. With this, the first elongate element W1 is guided by the slit 47c extending to the first insertion hole 47a, to be inserted from the outer circumferential surface 47f of the seal member <NUM> to the first insertion hole 47a. Also, the second elongate element W2 is guided by the slit 47c extending to the second insertion hole 47b, to be inserted from the outer circumferential surface 47f of the seal member <NUM> to the second insertion hole 47b.

The seal member <NUM> closes a part of the through hole <NUM> of the base <NUM> and is in close contact with the cover Cv covering the electric wire E. That is, the seal member <NUM> includes a through hole 47d. In the through hole 47d of the seal member <NUM>, the cover Cv covering the electric wire E is inserted. The through hole 47d of the seal member <NUM> penetrates through the seal member <NUM> in the Y direction. The number of the through hole 47d of the seal member <NUM> provided in the seal member <NUM> is one.

The seal member <NUM> is configured to be in close contact with the inner surface <NUM> (see <FIG>) of the base <NUM>. Specifically, the seal member <NUM> includes projected portions 47e or convex portions. The projected portions 47e are provided at positions corresponding to the second insertion holes 47b and to the recessed portions 45e of the base <NUM>. That is, a plurality (six, in this example) of the projected portions 47e are provided on the outer circumferential surface 47f of the seal member <NUM>. Each of the projected portions 47e is projected outwardly in the D direction from the outer circumferential surface 47f of the seal member <NUM>.

As illustrated in <FIG>, the retainer <NUM> according to an embodiment is configured to suppress unevenness in force pressing the surface <NUM> of the seal member <NUM> on the shaft <NUM> side. That is, the retainer <NUM> is configured to disperse the pressing force applied from the shaft <NUM> to the surface <NUM> of the seal member <NUM> on the shaft <NUM> side. The retainer <NUM> is made of a metal such as stainless steel or the like. Note that the retainer <NUM> is not limited to stainless steel, and may be formed of another material(s) such as metal or resin other than stainless steel, for example.

Specifically, the retainer <NUM> includes a pressing surface 48a, pressed portions 48b, a through hole 48c, and recessed portions 48d (escape portions). The retainer <NUM> is not in line contact with the surface <NUM> of the seal member <NUM> on the shaft <NUM> side but is in surface contact with the surface <NUM> by means of the pressing surface 48a of the retainer <NUM>. The pressing surface 48a is configured as an end surface of the retainer <NUM> on the end effector <NUM> side (the Y1 side).

The pressing surface 48a extends in the D direction and is in contact with the surface <NUM> of the seal member <NUM> on the shaft <NUM> side in an area from a center portion to an outer portion of the surface <NUM> in the D direction. The pressing surface 48a is pressed against the surface <NUM> of the seal member <NUM> on the shaft <NUM> side.

Accordingly, by means of the pressing surface 48a extending in the radial direction (the D direction) of the retainer <NUM>, the surface <NUM> of the seal member <NUM> on the shaft <NUM> side can be more evenly pressed by the shaft <NUM>. As a result, the seal member <NUM> can be more evenly compressed by the shaft <NUM>.

The pressing surface 48a is moved by the movement of the retainer <NUM> along with the movement of the shaft <NUM> toward the end effector <NUM> in the Y direction, so that the pressing surface 48a is in surface contact with and thus compresses the seal member <NUM>. Specifically, the base <NUM> includes the cutouts <NUM> recessed from the end of the base <NUM> on the shaft <NUM> side toward the end effector <NUM> side in the Y direction. The pressed portions 48b of the retainer <NUM> are arranged in the cutouts <NUM> of the base <NUM>. The pressed portions 48b of the retainer <NUM> is moved along the cutouts <NUM> of the base <NUM> so that the retainer <NUM> presses the seal member <NUM> with the pressing surface 48a.

Accordingly, when pressing the seal member <NUM> while the pressed portions 48b are moved along with the movement of the shaft <NUM>, the cutouts <NUM> of the base <NUM> can guide the movement of the retainer <NUM> toward the base <NUM>. Further, since the pressed portions 48b are arranged in the cutouts <NUM> of the base <NUM>, it is possible to suppress the movement (stop the rotation) of the retainer <NUM> in the R direction. As a result, the seal member <NUM> can be more evenly compressed by the retainer <NUM>.

The retainer <NUM> is configured to compress the seal member <NUM> by a predetermined length in the Y direction with the pressing surface 48a. Specifically, the retainer <NUM> is configured to compress the seal member <NUM> with the pressing surface 48a by the predetermined length in such a manner that the seal member <NUM> is positioned closer to the end effector <NUM> than the end of the cutout <NUM> of the base <NUM> on the end effector <NUM> side is.

Specifically, the pressing surface 48a of the retainer <NUM> is positioned closer in the Y direction to the end effector <NUM> (the Y1 side) than the surface <NUM> of the pressed portion 48b on a side away from the shaft <NUM> (an end effector side surface <NUM> of the pressed portion 48b).

Therefore, compared to a case where the pressing surface 48a is flush with the surface <NUM> of the pressed portion 48b on the end effector <NUM> side, the pressing surface 48a can be arranged closer to the Y1 side when the shaft <NUM> presses the retainer <NUM> in the Y1 direction. As a result, the seal member <NUM> can be sufficiently compressed by the retainer <NUM>.

As illustrated in <FIG> and <FIG>, the retainer <NUM> is configured to receive the pressing force from the shaft <NUM> at the outer portion of the shaft <NUM> in the D direction. Specifically, the retainer <NUM> is configured to receive the pressing force from the shaft <NUM> at a part of the surface of the retainer <NUM> opposite to the end effector <NUM> side in the Y direction. That is, the retainer <NUM> includes the pressed portions 48b that extend from the outer peripheral end of the pressing surface 48a outwardly in the D direction and that are pressed by the shaft <NUM>.

With this configuration, it is possible to more easily secure an area(s) pressed by the shaft <NUM> via the pressed portions 48b provided at the outer end of the pressing surface 48a, compared to a case where the shaft <NUM> directly presses the small-sized seal member <NUM> arranged in the base <NUM>.

Specifically, the pressed portions 48b are projected from the outer peripheral end of the pressing surface 48a outwardly in the D direction.

With this, the pressed portions 48b are not projected to the inside of the shaft <NUM> where the elongate elements and the electric wire are disposed but are projected toward the outer side of the shaft <NUM>. Therefore, it is possible to more easily secure an area(s) pressed by the shaft <NUM>.

The pressed portions 48b are configured to be pressed by the projections 42a of the shaft <NUM>. The pressed portion 48b are provided at positions corresponding to the projections 42a of the shaft <NUM>. That is, the pressed portions 48b are provided at positions outside the inner space 45d of the base <NUM> in the D direction.

The shaft <NUM> includes the projections 42a projecting in the Y direction. The pressed portions 48b are projected from the outer circumferential end of the pressing surface 48a outwardly in the D direction and provided at the positions facing (corresponding to) the projections 42a of the shaft <NUM> in the Y direction.

Accordingly, the pressed portions 48b of the retainer <NUM> and the projections 42a of the shaft <NUM> are disposed facing each other in the Y direction. Thus, the pressed portions 48b of the retainer <NUM> can be pressed more reliably by the shaft <NUM>. As a result, even in a case where there is restriction on layout of the positions pressed by the shaft <NUM>, the seal member <NUM> can be sufficiently pressed by the shaft <NUM> toward the base <NUM> side.

The retainer <NUM> is configured such that the pressing surface 48a of the retainer <NUM> is parallel to the plane along the D direction in the state where the pressed portions <NUM> receive the pressing force. That is, the plurality (two, in this example) of the pressed portions 48b are provided in the retainer <NUM> in order to uniformly disperse the pressing force applied to the pressing surface 48a to the pressing surface 48a.

Specifically, the plurality of the projections 42a of the shaft <NUM> and the plurality of the pressed portions 48b of the retainer <NUM> are arranged in the R direction. The plurality of the projections 42a and the plurality of the pressed portions 48b are arranged in point symmetry with respect to the center point in the D direction, as seen in the Y direction. The plurality (two) of the projections 42a, the plurality (two) of the pressed portions 48b, and the plurality (two) of the cutouts <NUM> are arranged in line symmetry with respect to a line extending in the D direction, as seen in the Y direction.

Since the point-symmetrically arranged plurality of the projections 42a press the point-symmetrically arranged plurality of the pressed portions 48b, the pressing force from the pressing surface 48a of the retainer <NUM> can be evenly applied to the surface <NUM> of the seal member <NUM> on the shaft <NUM> side. Therefore, the base <NUM> is stably sealed with the seal member <NUM>.

Each of the pressed portions 48b is provided overlapping with the corresponding projection 42a of the shaft <NUM> in the Y direction as seen from the opposite side of the end effector <NUM> side. That is, in the Y direction, the surface of the projection 42a of the shaft <NUM> on the end effector <NUM> side is larger than the surface of the pressed portion 48b of the retainer on the end shaft <NUM> side (that is, the opposite side of the end effector <NUM> side).

Here, the pressed portions 48b of the retainer <NUM> are provided at the positions outside the outer circumferential surface 47f of the seal member <NUM> and inside or same as (flash with) the outer circumferential surface 42b of the shaft <NUM> in the D direction.

Since the pressed portions 48b of the retainer <NUM> are provided at the positions inside or same as the outer circumferential surface 42b of the shaft <NUM> in the D direction, it is possible to avoid formation of protrusions on the outer circumferential surface of the shaft <NUM>. Further, since the pressed portions 48b of the retainer <NUM> are provided at the positions outside the outer circumferential surface 47f of the seal member <NUM> in the D direction, it is possible to securely press the pressed portions 48b of the retainer <NUM> by the shaft <NUM> even when the size of the base <NUM> is small. Therefore, it is possible to make the outer circumferential surface of the shaft <NUM> smooth and securely seal the base <NUM>.

As illustrated in <FIG>, the through hole 48c of the retainer <NUM> penetrates through the retainer <NUM> in the Y direction. The through hole 48c of the retainer <NUM> has a size in the D direction which allows the cover Cv of the electric wire E to be inserted. The through hole 48c of the retainer <NUM> is communicated with the through hole 47d of the seal member <NUM> in the Y direction. That is, the through hole 48c of the retainer <NUM> is provided at the center portion of the retainer <NUM> in the D direction.

In this way, the surgical instrument <NUM> is provided with the electric wire E for supplying electric energy to the end effector <NUM>. The seal member <NUM> includes the through hole 47d at the position corresponding to the position where the electric wire E is inserted through the seal member <NUM>. The retainer <NUM> includes the through hole 48c at the position corresponding to the position where the electric wire E is inserted through the seal member <NUM>.

With this, even in the case where the electric wire E is connected to the end effector <NUM>, it is possible to sufficiently compress the seal member <NUM> by the retainer <NUM> while securing the sealability of the base <NUM> by the seal member <NUM>.

The retainer <NUM> is configured to avoid interference between the retainer <NUM> and the first and second elongate elements W1 and W2. That is, the recessed portions 48d (escape portions) are provided at the positions around the first and second insertion holes 47a and 47b to which the first and second elongate elements W1 and W2 are inserted.

Specifically, the surgical instrument <NUM> includes the first elongate element W1 for rotating the end effector support body <NUM> with respect to the base <NUM> and the second elongate elements W2 for rotating the end effector <NUM> with respect to the end effector support body <NUM>. The seal member <NUM> includes the first insertion holes 47a to which the first elongate element W1 is to be inserted and the second insertion holes 47b to which the second elongate elements W2 are to be inserted. The retainer <NUM> includes the recessed portions 48d (escape portions) provided at the positions corresponding to the first and second insertion holes 47a and 47b to escape the first and second elongate elements W1 and W2 (avoid interference with the first and second elongate elements W1 and W2).

Accordingly, even in the case where the first elongate element W1 for rotating the end effector support body <NUM> and the second elongate elements W2 for rotating the end effector <NUM> are provided, it is possible to avoid interference between the retainer <NUM> and the first and second elongate elements W1 and W2 since the recessed portions 48d are provided in the retainer <NUM>. As a result, it is possible to stably perform the rotation of the end effector support body <NUM> by the first elongate element W1 and the rotation of the end effector <NUM> by the second elongate elements W2 while sufficiently compressing the seal member <NUM> by the retainer <NUM>.

Further, each of the recessed portions 48d is formed in a cutout shape recessed or concaved from the outer circumferential end of the retainer <NUM> toward the center of the retainer <NUM> in the D direction. The plurality (two, in this example) of the recessed portions 48d are arranged along the R direction. The plurality of the recessed portions 48d are arranged in point symmetry with respect to the center point of the retainer <NUM> or the shaft <NUM> in the D direction.

Specifically, the base <NUM> includes the recessed portions 45e recessed outwardly in the D direction from the inner circumferential surface <NUM> of the base <NUM> at the positions corresponding to the first and second insertion holes 47a and 47b. The seal member <NUM> includes the projected portions 47e at the positions corresponding to the recessed portions 45e of the base <NUM>. The recessed portions 48d are provided at the positions corresponding to the projected portions 47e.

With this, it is possible to securely avoid interference between the retainer <NUM> and the first and second elongate elements W1 and W2 even when the surgical instrument <NUM> uses the small-sized base <NUM> which may need the recessed portions 45e. As a result, it is possible to more stably perform the rotation of the end effector support body <NUM> by means of the first elongate element W1 and the rotation of the end effector <NUM> by means of the second elongate elements W2 while more sufficiently compressing the seal member <NUM> by the retainer <NUM>.

It should be understood that one or more embodiments described above are illustrated by way of example in every respect and not limit the invention. The scope of the invention is defined not by above-described one or more embodiments, but by the scope of claims, and includes all modifications (variations) within equivalent meaning and scope to those of the claims.

For example, in an embodiment described above, the pressing surface 48a extends in the plane along the D direction (radial direction). However, the invention is not limited to this. In the invention, plural pressing surfaces may be intermittently provided along the radial direction of the shaft.

Further, in an embodiment described above, the pressing surface 48a is provided closer to the end effector <NUM> than the surface <NUM> of the pressed portion 48b on the end effector <NUM> side (the side opposite from the shaft <NUM> side) in the axial direction of the shaft <NUM>. However, the invention is not limited to this. In the invention, the pressing surface and the surface of the pressed portion on the end effector side may be flush with each other with respect to the radial direction of the shaft.

Further, in an embodiment described above, the base <NUM> (support body) includes the recessed portions 45e recessed outwardly in the D direction from the inner circumferential surface <NUM> at the positions corresponding to the first and second insertion holes 47a and 47b. However, the invention is not limited to this. In the invention, the base <NUM> may not include the recesses.

Further, in an embodiment described above, the seal member <NUM> includes the projected portions 47e provided at the positions corresponding to the recessed portions 45e of the base <NUM> (support body). However, the invention is not limited to this. In the invention, the seal member may not include the projected portions.

Further, in an embodiment described above, the base <NUM> (support body) includes the cutouts <NUM> recessed from the end of the base <NUM> on the shaft <NUM> side toward the end effector <NUM> side in the Y direction. However, the invention is not limited to this. In the invention, the support body may not include the cutouts.

Further, in an embodiment described above, the pressed portions 48b of the pressing member are provided at the positions outside the outer circumferential surface 47f of the seal member <NUM> and inside or same as the outer circumferential surface 42b of the shaft <NUM> in the D direction. However, the invention is not limited to this. In the invention, the pressed portions of the pressing member may be provided at positions outside the outer circumferential surface of the shaft.

Claim 1:
A surgical instrument (<NUM>) to be attached to a robot arm (<NUM>, <NUM>), comprising:
an end effector (<NUM>);
an end effector support body (<NUM>) that supports the end effector to be rotatable about a first axis (A1);
a support body (<NUM>) that supports the end effector support body to be rotatable about a second axis (A2);
a shaft (<NUM>) to which the support body is connected and through which elongate elements (W1, W2) for operating the end effector are inserted;
a seal member (<NUM>) provided in the support body; and
a pressing member (<NUM>) including a pressing surface (48a) in contact with and pressing a surface (<NUM>) of the seal member on a side of the shaft, wherein
the pressing member comprises a pressed portion (48b) provided outside an outer peripheral end of the pressing surface in a radial direction of the shaft,
the pressed portion is projected outwardly in the radial direction of the shaft from the outer peripheral end of the pressing surface in the radial direction,
the shaft includes a projection (42a) projected in an axial direction (Y) of the shaft, and
the pressed portion is provided at a position opposed to the projection of the shaft in the axial direction of the shaft.