Lower thread winding device

In a lower thread winding device, a motor rotates a thread winding shaft on which a bobbin is mounted. A sensor lever includes a contact portion contactable with a lower thread wound on the bobbin, and a cam piece. A contact includes a pin configured to contact the cam piece and rotates between a first position at which the pin contacts a first outer peripheral portion of the cam piece, and a second position at which the pin contacts a second outer peripheral portion of the cam piece. A lever shifts a position of the pin located when the contact is at the first position. The controller drives the motor when the contact is at the first position and stops driving the motor upon receipt of a detection result, by the detector, indicating that the contact is at the second position.

TECHNICAL FIELD

Aspects of the disclosure relate to a lower thread winding device for winding a lower thread on a bobbin.

BACKGROUND

A known lower thread winding device includes a shaft, a motor, a distance measuring sensor. A bobbin is mounted on the shaft. The motor is coupled to the shaft. When the motor is driven, a lower thread is wound on the bobbin. The distance measuring sensor faces the bobbin along an axial direction of the shaft. When the outside diameter of the lower thread wound on the bobbin reaches a predetermined outside diameter, a voltage, which is a detection result by the distance measuring sensor, changes. Upon occurrence of a change in the detection result by the distance measuring device, the lower thread winding device stops driving the motor.

SUMMARY

However, in the known lower thread winding device, the motor continues to be driven until the outside diameter of the lower thread wound on the bobbin reaches the predetermined outside diameter, and the amount of lower thread to be wound on the bobbin is not adjustable. The amount of lower thread wound on the bobbin by the lower thread winding device may exceed or fall short of the amount desired by a user.

Aspects of the disclosure provide a lower thread winding device which allows a user to adjust the amount of lower thread to be wound on a bobbin.

According to one or more aspects of the disclosure, a lower thread winding device for winding a lower thread on a bobbin includes, a thread winding shaft on which the bobbin is mounted, a motor configured to rotate the thread winding shaft, a sensor lever rotatable about a first rotation shaft, a contact rotatable about a second rotation shaft different from the first rotation shaft, a detector, a lever, and a controller. The sensor lever includes a contact portion and a cam piece. The contact portion is contactable with the lower thread wound on the bobbin and configured to rotate about the first rotation shaft in a direction toward the bobbin and in a direction away from the bobbin. The cam piece is formed along a rotation direction about the first rotation shaft and includes a first outer peripheral portion and a second outer peripheral portion. A distance between the second outer peripheral portion and the first rotation shaft changes along the rotation direction. The contact includes a pin configured to contact the cam piece. The contact is configured to, when the sensor lever rotates in a rotation direction in which the contact portion moves away from the bobbin, rotate from a first position at which the pin contacts the first outer peripheral portion to a second position at which the pin contacts the second outer peripheral portion. The detector configured to output different detection results, depending on whether the contact is at the first position or at the second position. The lever is coupled to the contact and configured to shift a position of the pin located when the contact is at the first position in a direction toward the second outer peripheral portion and in a direction away from the second outer peripheral portion. The controller is configured to, when the contact is at the first position, drive the motor in a driving direction in which the lower thread is wound on the bobbin, and the controller is configured to, upon receipt of a detection result indicating that the contact is at the second position, stop driving the motor.

DETAILED DESCRIPTION

A lower thread winding device5according to an illustrative embodiment of the disclosure will be described.

As shown inFIG. 1, a sewing machine1includes a bed4, an upright arm3, and a horizontal arm2. The upright arm3extends upward from the bed4. The horizontal arm2extends horizontally from an upper end of the upright arm3. A needle plate23is disposed on the bed4. The needle plate23has a needle hole and the like. The bed4includes therein a shuttle mechanism (not shown). A shuttle of the shuttle mechanism is disposed below the needle plate23and accommodates therein a bobbin9on which a lower thread22(shown only inFIGS. 2 and 3) is wound. The bobbin9includes a pair of flanges facing each other and a cylinder connecting the pair of flanges. A cylindrical hole of the cylinder penetrates the pair of flanges. The lower thread22is wound on the cylinder. The upright arm3includes an operation unit17. The operation unit17includes a liquid crystal display and a touchscreen disposed on a surface of the liquid crystal display. A user pushes the operation unit17with a finger or a stylus.

An openable cover2A is rotatably disposed at an upper end of the horizontal arm2. The openable cover2A is rotated to open and close the inside of the horizontal arm2. The horizontal arm2includes therein a main shaft driven by a sewing machine motor (not shown). The horizontal arm2includes, at its distal end, a needle bar7which vertically moves by rotation of the main shaft. A needle is attached to a lower end of the needle bar7. An upper thread (not shown) is inserted into an eye (not shown) formed at a lower end of the needle. As the needle bar7vertically moves, the needle passes through the needle hole. The upper thread is caught by the shuttle driven in response to the needle bar7and then entangled with the lower thread22drawn from the bobbin9.

The horizontal arm2includes therein a lower thread winding device5and a spool pin18. The lower thread winding device5winds a lower thread22on the bobbin9. The spool pin18holds a thread spool which supplies a lower thread22to the lower thread winding device5. Upon insertion of the spool pin18into a through-hole of the thread spool, the thread spool is held by the spool pin18.

Referring toFIG. 2, the lower thread winding device5will be described. In the following description, a front-rear direction, a left-right direction, and a vertical direction, which are shown by arrows in the drawings, are used. The lower thread winding device5includes a frame15, a motor20, a sensor lever30, a contact40, an urging member16(refer toFIG. 3), a link70, a lever60, a cover55(refer toFIG. 1), and a detector50.

The frame15is plate-shaped to have a thickness in the vertical direction and is fixed inside the horizontal arm2. The motor20is fixed to a lower surface of the frame15. A drive shaft (not shown) of the motor20penetrates the frame15and extends upward. A thread winding shaft10extends upward from the drive shaft. The cylindrical hole of the cylinder of the bobbin9is put around the thread winding shaft10. The thread winding shaft10and the bobbin9are driven by the motor20to rotate integrally.

The sensor lever30is disposed rotatably about a first rotation shaft11which protrudes upward from the frame15. The first rotation shaft11is disposed behind the bobbin9. The sensor lever30includes a base31, an extending portion33, a contact portion32, and a cam piece35. The base31is substantially disc-shaped to have a thickness in the vertical direction and is rotatably coupled to the first rotation shaft11. The extending portion33protrudes upward from the base31. The contact portion32protrudes, along a rotation direction about the first rotation shaft11, from an upper end of the extending portion33toward the thread winding shaft10. As the sensor lever30rotates, the contact portion32rotates about the first rotation shaft11in a direction toward the bobbin9and in a direction away from the bobbin9.

The cam piece35is formed at an outer peripheral portion on the left of the base31, along the rotation direction about the first rotation shaft11. The cam piece35includes a first outer peripheral potion36and a second outer peripheral portion37. The first outer peripheral portion36and the second outer peripheral portion37are arranged in this order, about the first rotation shaft11, from a more counterclockwise position to a more clockwise position in plan view. The first outer peripheral portion36and the second outer peripheral portion37each have such a shape that a distance from the first rotation shaft11changes along the rotation direction about the first rotation shaft11. In this illustrative embodiment, a distance between the first outer peripheral portion36and the first rotation shaft11and a distance between the second outer peripheral portion37and the first rotation shaft11each decrease toward a more clockwise position about the first rotation shaft11in plan view. The first outer peripheral portion36extends in a curved manner, and the second outer peripheral portion37extends straight. The second outer peripheral portion37includes flat surfaces37A and37B. The flat surface37A is connected, at its one end, to an end of the first outer peripheral portion36and, at its other end, to an end of the flat surface37B.

The contact40includes a base41, a pin42, a switch contact portion46, and a lower protrusion47(refer toFIG. 3). The base41is substantially rectangular plate-shaped in plan view and movably disposed on an upper surface of the frame15. The base41includes, at its rear, a second rotation shaft12which protrudes upward. The base41is rotatable relative to the second rotation shaft12. The pin42is located in front of the second rotation shaft12and protrudes upward from the base41. The pin42contacts the cam piece35. The switch contact portion46protrudes upward from a front peripheral end of the base41. The switch contact portion46is elongate plate-shaped and contactable with a movable portion52of a detector50to be described later. The lower protrusion47(refer toFIG. 3) protrudes downward from the base41to penetrate the frame15.

An urging member16(refer toFIG. 3) urges the contact40in a rear-right direction and is coupled to a lower end of the lower protrusion47and to a lower portion of the frame15. The urging member16is, for example, a tension spring. The pin42is urged by the urging member16to contact the cam piece35.

As shown inFIG. 2, the link70is elongate plate-shaped to have a thickness in the vertical direction and is positioned above the contact40. A substantially central portion of the link70is rotatably coupled to the second rotation shaft12. One end of the link70is rotatable about a third rotation shaft13which protrudes upward from the frame15. The third rotation shaft13is disposed behind the sensor lever30. A protruding pin72is fixed to the other end of the link70to extend upward. A distance (which corresponds to a dimension L1shown inFIG. 5A) between the second rotation shaft12and the third rotation shaft13is less than a distance (which corresponds to a dimension L2shown inFIG. 5A) between the third rotation shaft13and the protruding pin72.

The lever60is disposed rotatably about a fourth rotation shaft14which protrudes upward from the frame15. The fourth rotation shaft14is disposed to the left of the contact40. The lever60includes a base61and a handle62. The base61is plate-shaped to have a thickness in the vertical direction and is rotatably coupled to the fourth rotation shaft14. The base61is disposed above the link70. The base61has, at its right portion, a coupling hole63. The coupling hole63is a slot elongate in a radial direction relative to the fourth rotation shaft14and penetrates the base61in a thickness direction. The protruding pin72of the link70is slidably fitted in the coupling hole63. Thus, rotation of the lever60allows the link70to rotate about the third rotation shaft13. The handle62is plate-shaped to have a thickness in a rotation direction about the fourth rotation shaft14and protrudes upward from a left portion of the base61. The handle62is aligned with the coupling hole63while sandwiching the fourth rotation shaft14therebetween. The handle62protrudes upward from the base61.

In the following description, the link70, the coupling hole63, and the protruding pin72are collectively referred to as a “link mechanism100”. The link mechanism100is coupled to the lever60and the contact40to transmit a rotational moving force of the lever60to the contact40. The contact40shifts, due to the force transmitted by the link mechanism100, in a substantially front-rear direction.

As shown inFIG. 3, the base61of the lever60includes, on its lower surface, irregularities67. The irregularities67include bumps and dents which are alternately arranged along a rotation direction of the lever60. In other words, the irregularities67extend in the rotation direction of the lever60. A contact member66slidably contacts the irregularities67. In this illustrative embodiment, the contact member66is an end of a leaf spring fixed to an upper surface of the frame15. The contact member66press-contacts the irregularities67. The contact member66is fitted in a dent of the irregularities67and the lever60is retained at the frame15.

Referring toFIG. 1, the cover55will be described. The cover55is substantially box-shaped to be open downward. The cover55includes a first opening56, a second opening57, and a third opening (not shown). The first opening56, the second opening57, and the third opening are each open in the vertical direction. The handle62is inserted in the first opening56, the extending portion33is inserted in the second opening57, and the thread winding shaft10is inserted in the third opening. The handle62, the extending portion33, and the thread winding shaft10each extend upward from the cover55and are exposed inside the horizontal arm2. The bobbin9and the contact portion32are also exposed inside the horizontal arm2. On the other hand, the cover55covers, from above, the base61of the lever60, the link mechanism100, the contact40, the base31of the sensor lever30, and the detector50(to be described later), which are shown inFIG. 2.

Referring toFIGS. 5 and 6, positional relationships between the sensor lever30, the contact40, and the lever60will be described. The sensor lever30rotates between an advanced rotation position (refer toFIGS. 5A and 6A) and a spaced rotation position (refer toFIGS. 5C and 6C). The advanced rotation position is a rotation position of the sensor lever30at which the contact portion32contacts the cylinder of the bobbin9. The spaced rotation position is a rotation position of the sensor lever30at which the contact portion32is spaced apart from the bobbin9in a rear-right direction. The sensor lever30rotates, about the first rotation shaft11counterclockwise in plan view, from the advanced rotation position to the spaced rotation position.

The contact40rotates about the second rotation shaft12between a first position (refer toFIGS. 5A and 6A) and a second position (refer toFIGS. 5C and 6C). The first position is a rotation position of the contact40at which the pin42contacts the first outer peripheral portion36of the sensor lever30. The second position is a rotation position of the contact40at which the pin42contacts the second outer peripheral portion37of the sensor lever30. When the sensor lever30is at the advanced rotation position, the contact40is at the first position. When the sensor lever30is at the spaced rotation position, the contact40is at the second position. The contact40rotates, about the second rotation shaft12counterclockwise in plan view, from the first position to the second position.

In the following description, a position at which the pin42of the contact40at the first position contacts the first outer peripheral portion36is referred to as a “specific contact position” (refer toFIGS. 5A and 6A). When the pin42at the specific contact position contacts the first outer peripheral portion36, the first outer peripheral portion36restricts the contact40urged by the urging member16from rotating toward the second position. In contrast, when the pin42contacts the second outer peripheral portion37, the contact40urged by the urging member16rotates, with the pin42sliding the second outer peripheral portion37, toward the second position.

The lever60rotates between a first adjusted rotation position (refer toFIGS. 5A to 5C) and a second adjusted rotation position (refer toFIGS. 6A to 6C). The first adjusted rotation position is a rotation position of the lever60at which a substantially central portion of the coupling hole63contacts the protruding pin72. The second adjusted rotation position is a rotation position of the lever60at which an end of the coupling hole63closer to the fourth rotation shaft14contacts the protruding pin72. The lever60rotates counterclockwise in plan view from the first adjusted rotation position to the second adjusted rotation position. Rotation of the lever60between the first adjusted rotation position and the second adjusted rotation position shifts the specific contact position of the pin42. In this illustrative embodiment, as the rotation position of the lever60shifts toward the second adjusted rotation position, the specific contact position of the pin42shifts toward the second outer peripheral portion37(refer toFIGS. 5A and 6A).

Referring toFIG. 2, the detector50will be described. The detector50in this illustrative embodiment is a leaf switch. The detector50includes the movable portion52and an elastic member (not shown). The movable portion52is rotatable about a specific axis extending in the vertical direction. The elastic member urges the movable portion52in a predetermined direction. The predetermined direction is a clockwise direction about the specific axis in plan view and corresponds to an arrow B. When the contact40is at the first position (refer toFIG. 5A), the switch contact portion46contacts the movable portion52, thereby restricting rotation of the movable portion52in the predetermined direction. At this time, the movable portion52is positioned at one end of a movable range. When the contact40is at the second position (refer toFIG. 5C), the switch contact portion46moves rightward away from the movable portion52which in turn moves to the other end of the movable range. The detector50outputs different detection results, depending on whether the movable portion52is at one end or at the other end of the movable range. In other words, the detector50outputs different detection results, depending on whether the contact40is at the first position or at the second position.

Referring toFIG. 4, the electrical configuration of a controller90will be described. The controller90is included in a sewing machine controller (not shown) for controlling operation of the sewing machine1. The controller90includes a CPU91, a ROM92, a RAM93, a flash memory94, and an input/output interface (I/F)96. The CPU91is connected, via a bus95, to the ROM92, the RAM93, the flash memory94, and the input/output I/F96.

The CPU91conducts main control over the sewing machine1and the lower thread winding device5and executes various calculations and processing according to various programs stored in the ROM92. The RAM93includes a storage area for storing calculation results calculated by the CPU91. The flash memory94stores therein various parameters for the sewing machine1and the lower thread winding device5to execute various processes. A drive circuit71, the operation unit17, and the detector50are connected to the input/output I/F96. The motor20is connected to the drive circuit71. The CPU91controls driving of the motor20by sending control signals to the drive circuit71. The operation unit17detects an operation result by a user and outputs a detection result to the CPU91. The detector50outputs a detection result to the CPU91. The detection result by the detector50is an ON signal or an OFF signal. The detection result by the detector50changes, depending on whether the movable portion52is at one end or at the other end of the movable range.

Referring toFIGS. 1, 4, and 5, operation of the lower thread winding device5when the lever60is at the first adjusted rotation position will be described. A user rotates the openable cover2A to open the inside of the horizontal arm2and mounts the bobbin9on the thread winding shaft10, and then ties a lower thread22drawn from the thread spool to the cylinder of the bobbin9. Thereafter, the user holds the contact portion32to rotate the sensor lever30from the spaced rotation position to the advanced rotation position (refer toFIG. 5A). Upon operation of the operation unit17by the user, the CPU91starts driving the motor20. The motor20is driven in such a direction that the lower thread22is wound on the bobbin9. Even when the motor20is driven, the lever60and the link70remain stationary.

When the bobbin9rotates, upon driving of the motor20, to wind the lower thread22on the cylinder, the contact portion32contacts the lower thread22instead of the cylinder of the bobbin9. As the lower thread22is wound on the cylinder, a contact position between the contact portion32and the lower thread22gradually moves away from the thread winding shaft10. This causes the sensor lever30to rotate toward the spaced rotation position (as shown by an arrow A1inFIG. 5A) and the first outer peripheral portion36to slide relative to the pin42. A contact position between the pin42and the first outer peripheral portion36gradually shifts toward the first rotation shaft11. Consequently, the contact40urged by the urging member16gradually rotates about the second rotation shaft12from the first position toward the second position (refer toFIGS. 5A and 5B).

When the pin42contacts the flat surface37A of the second outer peripheral portion37, instead of the first outer peripheral portion36, the pin42urged by the urging member16slides along the flat surface37A while moving the cam piece35substantially rightward. This causes the contact40to rotate further toward the second position (as shown by an arrow A2inFIG. 5B) and the sensor lever30to rotate further toward the spaced rotation position (as shown by an arrow A1inFIG. 5B).

As shown inFIG. 5C, immediately after the switch contact portion46moves away from the movable portion52, the contact40reaches the second position and the sensor lever30reaches the spaced rotation position. The contact40and the sensor lever30stop. The second position of the contact40when the lever60is at the first adjusted rotation position is a rotation position at which the pin42contacts a boundary between the flat surface37A and the flat surface37B. When the switch contact portion46moves away from the movable portion52, the movable portion52rotates to the other end of the movable range, and the detection result by the detector50changes. The changed detection result by the detector50indicates that the contact40is at the second position. Upon receipt of the changed detection result by the detector50, the CPU91stops driving the motor20. The lower thread winding device5ceases to operate and a predetermined amount of the lower thread22is wounded on the cylinder of the bobbin9.

Referring toFIGS. 2 and 6, operation of the lower thread winding device5when the lever60is at the second adjusted rotation position will be described. Hereinafter, a repetitive description of the same or similar operation of the lower thread winding device5described above will be omitted.

The user rotates the sensor lever30to the advanced rotation position and then hold the handle62to rotate the lever60from the first adjusted rotation position to the second adjusted rotation position. When the lever60is rotated, the irregularities67(refer toFIG. 3) slide relative to the contact member66. Rotation of the lever60causes the link70to rotate about the third rotation shaft13clockwise in plan view. The link70moves, via the second rotation shaft12, the contact40rearward. Consequently, the specific contact position of the pin42shifts more rearward (i.e., toward the flat surface37A) than when the lever60is at the first adjusted rotation position. Thereafter, when the CPU91starts driving the motor20, the lower thread22is wound on the bobbin9and the sensor lever30rotates counterclockwise in plan view (as shown in an arrow A1inFIG. 6A).

After driving of the motor20is started, the pin42slides to a rear end of the first outer peripheral portion36(refer toFIG. 6B). A period of time taken, after the motor20is driven, for the pin42to contact the rear end of the first outer peripheral portion36is shorter than when the lever60is at the first adjusted rotation position. When the pin42slides the flat surface37A instead of the first outer peripheral portion36, the contact40rotates further toward the second position and the sensor lever30rotates further toward the spaced rotation position.

As shown inFIG. 6C, after the switch contact portion46moves away from the movable portion52, the pin42slides the flat surface37B instead of the flat surface37A. Thereafter, the sensor lever30reaches the spaced rotation position and the contact40reaches the second position. The second position of the contact40when the lever60is at the second adjusted rotation position is a rotation position of the contact40at which the pin42contacts the flat surface37B. A timing at which the switch contact portion46moves away from the movable portion52(i.e., a timing at which the detection result by the detector50changes) is earlier than when the lever60is at the first adjusted rotation position. Accordingly, the amount of the lower thread22wound on the bobbin9is less than when the lever60is at the first adjusted rotation position.

The user may stop the lever60at a rotation position between the first adjusted rotation position and the second adjusted rotation position to operate the lower thread winding device5. In other words, the user is allowed to readily and freely adjust the amount of the lower thread22to be wound on the bobbin9by changing the rotation position of the lever60.

As described above, when the lever60rotates between the first adjusted rotation position and the second adjusted rotation position, the specific contact position of the pin42shifts in a direction away from the flat surface37A of the second outer peripheral portion37and in a direction toward the flat surface37A. The user rotates the lever60to shift the specific contact position of the pin42. This changes the rotation amount of the contact40necessary for the detector50to change the detection result. Accordingly, operation of the lever60by the user changes the amount of the lower thread22to be wound on the bobbin9until the controller90stops the motor20after starting driving the motor20. The lower thread winding device5is thus achieved in which the user is allowed to adjust the amount of the lower thread22to be wound on the bobbin9.

The cover55exposes the handle62which is a portion of the lever60and covers from above the contact40. This may prevent the user from inadvertently touch the contact40and facilitate the user to properly operate the handle62.

The lower thread winding device5includes the link mechanism100. The link mechanism100may prevent a direct transmission of a rotation force of the lever60to the contact40. The link mechanism100may prevent transmission of an excessive force to the contact40, and thus the lower thread winding device5may prevent a failure of the contact40.

The link mechanism100includes the link70rotatable about the third rotation shaft13. The link mechanism100converts a rational moving force of the lever60to a rotational moving force of the link70, thereby preventing a direct transmission of the force from the lever60to the contact40.

The dimension L1(refer toFIG. 5A) is less than the dimension L2(refer toFIG. 5A). Namely, the distance between the second rotation shaft12and the third rotation shaft13is less than the distance between the coupling position of the lever60to the link70(i.e., the position of the protruding pin72) and the third rotation shaft13. When the lever60rotates, this makes a rotational moving amount, about the third rotation shaft13, of the second rotation shaft12less than a rotational moving amount, about the third rotation shaft13, of the coupling position of the lever60to the link70. The lower thread winding device5is thus allowed to reduce a rotational moving amount of the contact40as the lever60rotationally moves, thereby allowing the user to finely adjust the specific contact position.

The lever60is rotatable about the fourth rotation shaft14. The lower thread winding device5is thus allowed to shift the specific contact position by rotational movement of the lever60.

The lower thread winding device5includes the contact member66configured to slidably contact the base61of the lever60. The contact member66in contact with the base61makes the lever60less easy to rotate, thereby allowing the user to finely adjust the rotation position of the lever60. Accordingly, the user is allowed to finely adjust the amount of the lower thread22to be wound on the bobbin9by the lower thread winding device5.

The contact member66press-contacts the irregularities67of the base61. This makes the lever60much less easy to rotate and facilitates finer adjustment of the rotation position of the lever60in the lower thread wining device5.

The detector50issues different detection results, depending on whether the movable portion52and the switch contact portion46contact each other. The detector50readily detects whether the contact40is at the first position or at the second position.

The disclosure may not be limited to the above-described illustrative embodiment, and various changes may be applied therein. The lower thread winding device5may be a single unit separate from the sewing machine1. In this case, the lower thread winding device5may be easily portable. The lever60may be lineally movable, for example, along the front-rear direction, instead of rotationally movable. In this case, the irregularities67extends lineally.

The disposition and orientation of the lower thread winding device5may not be limited to the above-described illustrative embodiment. For example, the lower thread winding device5may be disposed such that the thread winding shaft10, the first rotation shaft11, the second rotation shaft12, and the third rotation shaft13extend in the left-right direction. In this case, if the pin42contacts from above the cam piece35, the lower thread winding device5may lack the urging member16. The pin42press-contacts the cam piece35due to the own weight of the contact40. The first outer peripheral portion36may be an arc of a perfect circle about the first rotation shaft11. The second outer peripheral portion37may be curved. In this case also, a distance between the second outer peripheral portion37and the first rotation shaft11changes along a rotation direction about the first rotation shaft11. The distance between the second outer peripheral portion37and the first rotation shaft11may get longer toward a clockwise side about the first rotation shaft11in plan view. In this case, the contact40at the first position rotates about the third rotation shaft13clockwise in plan view to reach the second position. The cam piece35may be formed, for example, at an outer peripheral potion of the contact portion32. In this case, the dispositions of the contact40and other elements are changed as appropriate.

The third rotation shaft13may be omitted. In this case, the link70may be rotatably disposed at the first rotation shaft11. In this modification, the first rotation shaft11is an example of a third rotation shaft according to an aspect of the disclosure. Alternatively, when the third rotation shaft13is omitted, the link70may be rotatably disposed at only the second rotation shaft12. In this modification, the second rotation shaft12is an example of a third rotation shaft according to an aspect of the disclosure. The fourth rotation shaft14may be omitted. In this case, the lever60may be rotatably disposed at the first rotation shaft11. In this modification, the first rotation shaft11is an example of a fourth rotation shaft of the disclosure.

The movable portion52of the detector50may be contactable with, for example, the contact portion32, instead of the switch contact portion46. In this case, the movable portion52may be spaced apart from the contact portion32when the sensor lever30is at the advanced rotation position, and may be in contact with the contact portion32when the sensor lever30is at the spaced rotation position. The detector50may be, for example, an optical sensor, instead of a limit switch. The link70, instead of the lever60, may have the coupling hole63. In this case, the coupling hole63is elongate in a radial direction relative to the third rotation shaft13, and the protruding pin72protrudes downward from the lever60.