medical devices

Abstract

An instrument feeding device (201) for use in an endoscope system for feeding a medical instrument (202) into or extracting a medical instrument from a body, the instrument feeding device comprising: a connector (302) for connecting the instrument feeding device (201) to a motor 5 (203) for moving the medical instrument (202) through the instrument feeding device (201); a drive wheel (303) arranged to be rotated by the motor, wherein the drive wheel (303) is positioned on one side of the medical instrument (202) An idler wheel (310) is positioned on the opposite side of the medical device (10) relative to the drive wheel (303); a clutch mechanism is suitable for pushing the idler wheel (310) against the medical device (202), the clutch mechanism comprising a rotation button (1012) connected to a main shaft (1111), the main shaft comprising a main part (1111b) and an eccentric part (1111a), the eccentric part being arranged to be offset relative to a center line passing through the main part (15), wherein the idler wheel is rotatably mounted on the eccentric part of the main shaft.

Description

Technical Field

[0001] The present invention relates to a device for inserting and removing a medical device into and from an instrument channel of an endoscope. Background Art

[0002] Endoscopy, including colonoscopy, gastroscopy, and enteroscopy, is a medical procedure used to determine the presence of any disease in the digestive tract, such as inflammation, infection, precancerous changes, ischemia, or tumors. Diagnostic endoscopy is the process of examining the digestive tract and sampling tissue (i.e., biopsy) or fluid (i.e., cytology). This procedure can be performed on humans or animals. Analysis of the tissue or fluid sample allows for diagnosis of the condition. For example, conditions such as gastritis, Crohn's disease, ulcers, and malignant tumors can be diagnosed. In addition to diagnostic examinations, endoscopic procedures also include therapeutic procedures such as polyp removal, bleeding control, and placement of devices (e.g., expandable stents).

[0003] Endoscopy procedures are an important tool for medical practitioners and are routinely performed by gastroenterologists. The medical instruments required for diagnostic and therapeutic endoscopic procedures are inserted into the body through an instrument channel and pushed along the channel until they reach their intended point of use. For the medical practitioner performing an endoscopy, it is necessary to have someone assist them by holding one end of the medical instrument while they push the instrument through the channel by holding the other end. The medical instruments can be 1.2-1.6 meters long, and the process of inserting them is complex and time-consuming.

[0004] Patent documents EP1769722A2 and EP3155953A1 disclose endoscope systems that include an electrically operated drive unit for advancing a medical instrument into and out of an instrument channel. This arrangement can reduce the need for an assistant to insert the medical instrument, but can limit the medical practitioner's freedom of movement when using the instrument.

[0005] US Pat. No. 8,114,032 describes a feeding device for an endoscope system, wherein the feeding device is adapted to be connected to a drive motor via a drive shaft. The feeding device includes a plurality of drive wheels that rotate in response to rotation of the drive shaft; the feeding device also includes a clutch mechanism adapted to provide secure contact between one or more of the drive wheels and the endoscope cable when engaged. The clutch engages a ratchet mechanism. Summary of the Invention

[0006] An object of the present invention is to provide an instrument feeding device for use in an endoscope system for feeding medical instruments into the body, wherein the medical practitioner can operate the device without being hindered by the device. Another object is to provide an instrument feeding device in which the endoscope system can be easily sterilized. A further object of the present invention is to provide a low-cost instrument feeding device.

[0007] The object is achieved in the following instrument feeding device:

[0008] The instrument feeding device is used to feed a medical instrument into a body or remove the medical instrument from the body, and comprises:

[0009] a connector for connecting the instrument feeder to a motor for moving the medical instrument through the instrument feeder;

[0010] a drive wheel arranged to be driven to rotate by the motor, wherein the drive wheel is positioned on one side of the medical device, and an idler wheel is positioned on the opposite side of the medical device relative to the drive wheel,

[0011] a clutch mechanism adapted to push the idler wheel against the medical device, and thereby push the medical device against the drive wheel, to maintain the idler wheel in an activated position against the medical device, and further adapted to release the idler wheel from the activated position,

[0012] wherein the clutch mechanism comprises a rotary button connected to a main shaft, the main shaft comprising a main portion and an eccentric portion, the eccentric portion being arranged offset relative to a centerline passing through the main portion, wherein the idler gear is rotatably mounted on the eccentric portion of the main shaft,

[0013] wherein the rotation button comprises a rod that is hollow and slidably mounted to the main portion of the spindle, the rod comprising: a recess that engages with a corresponding rib on the main portion of the spindle to allow the rotation button to rotate the spindle; a protrusion on the rod that engages with a conical protrusion on a wall surrounding the device; and a spring that urges the protrusion against the conical protrusion. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Further advantages and features of the present invention will become apparent from the following detailed description and the accompanying drawings, in which

[0015] Figure 1 is a schematic diagram of an endoscope system (prior art),

[0016] Figure 2 Shows how the first embodiment of the instrument feeder can be incorporated into Figure 1Schematic diagram of the system,

[0017] Figure 3 This is an external view of the feed unit.

[0018] Figure 4 Shows the internal mechanism of the feeding device,

[0019] Figure 5 It is a partial cross-sectional view of the feeding device.

[0020] Figure 6a , b shows another embodiment of the present invention,

[0021] Figure 7 is a schematic diagram of the components included in the embodiment shown in FIG6 ,

[0022] Figure 8a -c shows another component of this embodiment, and

[0023] Figure 9a , b shows details of the components shown in Figure 8.

[0024] Figure 10 is an external view of another embodiment of the feeding device,

[0025] Figure 11 is a perspective view of the internal structure of this embodiment,

[0026] Figure 12 is a cross-sectional view of the embodiment shown in FIG6,

[0027] Figure 13 is another cross-sectional view of this embodiment, which is perpendicular to Figure 7 View,

[0028] Figure 14 is a perspective view of the components used in this embodiment, and

[0029] Figure 15 Show Figure 14 A perspective view of how the components are installed in the feeding device of the present invention. DETAILED DESCRIPTION

[0030] Figure 1 An endoscope 101 according to the prior art is shown. The endoscope 101 may be, for example, a gastroscope or a colonoscope.

[0031] will include instrument channel 102 (in Figure 1 The insertion tube 103 (referred to as the biopsy channel in the figure) is inserted into the patient's body. Figure 1As shown, the first end of instrument channel 102 has an opening, allowing a medical device to be inserted into instrument channel 102. At the end of insertion tube 103, which is inserted into the body, the second end of instrument channel 102 has an opening, through which the medical device inserted into the first end of instrument channel 102 can pass. During use, the medical device is inserted into the first end of instrument channel 102 and passed through instrument channel 102 until it is exposed through the second end of instrument channel 102. It can then be pushed further into the body until it reaches the point of use for performing a diagnostic or therapeutic procedure.

[0032] The medical device inserted into the instrument channel 102 includes an instrument portion and an elongated portion. The instrument portion may include, for example, scissors for obtaining tissue samples. The elongated portion includes one or more wires or tubes and supports the instrument portion so that it can be moved along the channel to the point of use in the body and can also be operated at the point of use.

[0033] The medical instrument can be, for example, a biopsy forceps, a polyp snare, a rubber band ligation device, a retrieval basket, or any other medical instrument. The endoscope 101 can be any flexible endoscopic instrument for providing a passage for a medical instrument to enter the body. The endoscope 101 is preferably a gastroscope, a colonoscope, or an enteroscope.

[0034] According to known techniques, a medical device is inserted into the first end of instrument channel 102. This insertion is typically performed by the surgeon performing the procedure and an assistant. The surgeon manually pushes the medical device through instrument channel 102. Medical devices can be 1.2-1.6 meters long, and the insertion process is slow. Because a surgeon may need to push and pull a medical device through instrument channel 102 for an effective length of 100 meters in a single day, inserting and removing medical devices can be stressful for the surgeon.

[0035] Figure 2 A system according to the present invention is shown comprising an instrument feed device 201 , a motor 203 , a drive shaft, a power supply for the motor 203 , and a medical instrument 202 passing through the instrument feed device 201 .

[0036] The elongated portion of the medical device 202 passes through the instrument feeding device 201. The instrument feeding device 201 includes a plurality of wheels that contact the medical device 202 in the instrument feeding device 201. The rotation of the wheels forces the medical device 202 to pass through the instrument feeding device 201. The instrument feeding device 201 also includes a connector for being connected to the end of the drive shaft. The connector connected to the drive shaft is physically separated from the wheel in the instrument feeding device 201 so that the connection and use of the non-cleaned drive shaft will not contaminate the clean medical device 202 that is passing through the instrument feeding device 201, and the non-cleaned medical device 202 passing through the instrument feeding device 201 will not contaminate the clean drive shaft. The physical separation of the connector and the wheel can be any structure that isolates the drive shaft and the wheel from each other so that they do not contaminate each other. The instrument feeding device 201 may include one or more shields for ensuring that the connected drive shaft and the medical device 202 do not contaminate each other.

[0037] The drive shaft can be any type of shaft or cable capable of transmitting the torque of the motor 203 to the instrument advancement device 201. For example, the drive shaft can be a flexible Bowden cable (speedometer). The drive shaft can alternatively be a non-flexible shaft. The drive shaft can alternatively be replaced by a hydraulic turbine or a small electric servo motor.

[0038] In an alternative embodiment, the motor can be integrated into the main endoscope unit. The feeding device can then be connected directly to the motor without any intervening drive shaft. In another embodiment, the motor and the battery used to power it can be integrated into the feeding device. The entire unit can then be discarded after use.

[0039] The instrument feeder 201 is configured such that the direction of rotation of the one or more wheels that force the medical instrument 202 through the instrument feeder 201 depends on the direction of rotation of the motor. Thus, by reversing the direction of rotation of the motor, the operation of the instrument feeder 201 can be changed from pushing the instrument into the body to pulling the instrument out of the body.

[0040] Advantageously, the instrument feeding device 201 is driven by a remote motor 203. The instrument feeding device 201 does not include the motor 203, and this reduces the cost of the instrument feeding device 201.

[0041] After use of the instrument feeder 201, the instrument feeder 201 can be disconnected from the motor / drive shaft and disposed of. A new instrument feeder 201 can be connected to the same motor / drive shaft, and another biopsy operation can be performed quickly and easily.

[0042] Figure 33 is an external view of the instrument feeding device of the present invention. The device includes a housing having an input port 301a for medical instruments and an output port 301b for forming an instrument channel insertion plug. In addition, there is a contact 302 for connecting a drive shaft or Bowden cable from an external motor 203 or for directly contacting the motor, a push button 312 for operating an internal clutch mechanism to engage the instrument feeding device 201 to the medical instrument 202, and a release button 313 for releasing the engagement between the feeding device and the medical instrument. In the embodiment shown in the figure, the contact 302 is a hexagonal type. However, any type of suitable contact may be used, such as a spline type, a blade type contact, etc.

[0043] When using the endoscope system, the instrument feeder 201 is connected to the endoscope system by inserting the insertion plug 301b into the system. If connected to the endoscope 101, the preferred point is at the end of the instrument channel 102. This connection ensures that the instrument feeder 201 remains effectively stationary while the medical instrument 202 is moved through it. Alternatively, the instrument feeder 201 can be held by a healthcare practitioner. The medical instrument is then passed through the feeder. A push button is pressed to engage the drive mechanism in the feeder with the medical instrument. An external drive unit, such as a foot pedal (i.e., a switch), can then be activated to advance the medical instrument into the instrument channel of the endoscope system. The medical instrument is advanced into the instrument channel until it is approximately 5 cm from the end of the channel. When the instrument is positioned in the desired position near the end of the instrument channel, the release button is pressed, releasing the engagement between the feeder and the medical instrument. The healthcare practitioner can then operate the medical instrument completely independently of the feeder and manually advance it further into the patient's body. This is a safety measure to ensure that the medical device will not harm the patient.

[0044] Figure 4 The internal components of the instrument feeder 201 are shown. The instrument feeder includes a housing having two ports 301a, 301b on opposite sides thereof through which the medical instrument 202 passes. The medical instrument 202 can pass through the instrument feeder 201 in both directions. The drive mechanism that moves the medical instrument through the instrument feeder preferably includes two upper drive wheels 303a and 303b inside the encapsulating shell, each drive wheel being adapted to contact the medical instrument 202.

[0045] The drive wheels have a solid core and an outer portion made of a soft material such as rubber. The solid core can be made of plastic, and the soft outer portion is molded onto it to ensure a secure connection between the two components, thereby preventing any slippage between them. The soft outer portion of each wheel provides good frictional contact with the medical device, which is necessary to enable the device to move. However, the rubber outer portion on each wheel should be of appropriate thickness. This means that the rubber portion should not be too thick so that the medical device is completely embedded in the rubber or surrounded by the rubber when the drive wheel and idler wheel are closed together, thereby preventing the hard inner core from exerting sufficient pressure and gripping on the medical device.

[0046] The outer circumference of the wheel may also be textured as shown (herringbone or tractor pattern) to further increase friction between the wheel and the medical device, which may be quite smooth.

[0047] Each drive wheel is connected to a corresponding gear wheel 305a, b. Of course, each drive wheel and associated gear wheel can be manufactured as a single unit. The gear wheels 305a, b mesh with a common transfer gear wheel 306, which can be connected to a worm gear mechanism via a stub shaft 307. The worm gear mechanism includes a gear wheel 308 meshing with a worm 309. The end of the worm 309 protrudes through the housing and terminates in a contact 302 for engagement with a drive shaft that provides rotational power from an external motor 203.

[0048] This is the mechanism that drives the medical device forward and backward. However, in order to properly engage the drive wheels 303a, b of the drive mechanism with the medical device 202, a clutch mechanism is provided in the instrument feeder 201. This clutch mechanism includes an idler wheel 310, which can be pressed against the underside of the medical device 202, pressing it toward the two drive wheels 303a, b above. The idler wheel 310 can also be provided with a soft outer portion 311. The idler wheel can be pressed toward the medical device using a push button 312, and there is a ratchet mechanism suitable for holding the idler wheel in the engaged position. There is also a release button 313 for disengaging the ratchet mechanism, thereby releasing the engagement of the wheels. In this way, the structure acts as a clutch, allowing the instrument feeder to move the medical device to position it and then release the engagement between the device and the device, providing complete freedom for the medical practitioner to operate the device.

[0049] Figure 4 The worm gear mechanism shown has the advantage that it can provide a braking function, preventing the medical instrument from being able to move back through the feeder when the device is not activated. However, the worm gear mechanism can also be omitted, and the drive cable or motor can be connected directly to one of the wheels via suitable contacts on the side of the housing. The motor must be able to drive the feeder at a suitable rotational speed and can therefore include a gear mechanism.

[0050] An advantage of this embodiment with two drive wheels and a single idler wheel facing the drive wheel is that the medical device will bend slightly as it passes over the wheel. This increases the contact surface and friction between the wheel and the device. However, alternative embodiments are contemplated, such as a reverse configuration with a single drive wheel and two idler wheels, or a configuration with a single drive wheel and a single idler wheel opposite the drive wheel, or two drive wheels and two idler wheels, each idler wheel directly facing the drive wheel.

[0051] Figure 5 is based on Figure 4 A cross-sectional view of an instrument feeding device. The worm gear mechanism and the idler wheel have been removed to show the ratchet mechanism that holds the idler wheel toward the medical instrument. The mechanism includes a push button 312 flush with the outer wall. The push button includes a hinge shaft 401, a spring member 402, and a protruding ratchet member 406. The push button is hinged to the outer wall at one end via the hinge shaft 401. The spring member 402 protrudes from the hinge shaft and pushes the push button toward the outer wall. Figure 5 The mechanism also includes a key 403. This key 403 includes a tip 405 that engages the toothed path of a ratchet component 406. When the push button is pressed, the idler wheel is pressed against the medical instrument, further pressing against the drive wheel. Simultaneously, the key slides along the toothed portion, locking onto the ratchet component and thus preventing the idler wheel from returning when the operator releases pressure on the button. In this position, the operator can operate the motor, for example using a foot pedal, to position the medical instrument. When the instrument is correctly positioned, the clutch mechanism can be released. This is accomplished by pressing a release button 313. This button is not shown in the figure, but is mounted on a cross-shaped protrusion 407. By pressing this button, the ratchet component bends and disengages from the key. The button, with the idler wheel and key, then snaps into its initial position and releases its grip on the medical instrument.

[0052] A crucial requirement is that medical devices are initially clean when inserted into the body. When a clean medical device is introduced into the body, all parts of the device delivery system that contact the device must also be clean. Otherwise, contact will cause the device to lose its cleanliness properties, resulting in contamination. Therefore, at the beginning of an endoscopic procedure, all involved components must be clean. By the time the procedure is complete, both the medical device and the delivery system will be contaminated. While the device can be cleaned, subsequent cleaning of a non-cleaned device delivery system is difficult and expensive.

[0053] To avoid this problem, the instrument feeder of the present invention is preferably a single-use device. The instrument feeder is provided in a clean, never-before-used state at its point of use. After use, the instrument feeder is typically discarded, and the unused, clean instrument feeder is used for the next endoscopic procedure. Advantageously, each instrument feeder does not need to be sterilized after use.

[0054] Since each instrument feeding device is disposed of after a single use, the manufacturing cost of the instrument feeding device is preferably low.Therefore, the instrument feeding device according to this embodiment is preferably composed of low-cost components.

[0055] Figure 6a An embodiment of the present invention is shown, which is designed to reduce the cost of the system. To this end, the instrument feeding device includes two parts, namely a gear section 604 and a separate feed box 605. Only the feed box is processed after each inspection cycle. The gear section 604 includes a drive mechanism and a clutch mechanism with a push button 312 and a release button 313. The driving force is transmitted through a drive cable 601 (or another shaft from the motor) and is transmitted to the feed box 605 via two output shafts 602 and 603. The box includes input and output ports 301a, b for receiving medical instruments and drive wheels for feeding the instruments therethrough. Figure 6b The cassette is shown mounted to the gear portion.

[0056] Figure 7 The internal components of the feed cassette are shown. This embodiment uses only one drive wheel 704 and one idler wheel 703, which are constructed identically to the previous embodiment, each having axles 707 and 706 adapted to engage the output shafts 602 and 603. The upper shaft is supported at each end in an oblong hole 705, allowing the idler wheel to move along the hole.

[0057] Figure 8a 602 is a cross-section through the gear section with the upper shaft in its upper position, meaning the feed cassette will not engage a medical device. The push button 312 includes a protrusion that engages a slot in the upper output shaft 602. The release button 313 includes a key 802 adapted to engage a ratchet 803 in the protrusion of the push button 312.

[0058] Figure 8b Shown is the gear assembly with the push button 312 depressed. The button is hinged to the enclosure in hinge 804, and the protrusion will force the upper output shaft 602 downwards, while the key 802 engages the ratchet and locks the push button in its depressed position.

[0059] exist Figure 8cIn the embodiment, the release button 313 is depressed because the release button is hinged to the encapsulating shell in the hinge 801, thereby removing the key 802 from its engagement with the ratchet. Then, the output shaft 602 on the upper side returns to its initial position.

[0060] Figure 9a , b shows how the push button 312 engages the output shaft 602 on the upper side, entering a slot in the shaft.

[0061] However, a solution with two drive wheels and one or two idler wheels can also be designed using a separate feed cassette.

[0062] During the development of new feeding devices, it has been found that Figure 2 -9 has some strengths and weaknesses. First, the soft drive wheel with its textured outer layer provides sufficient grip on the instrument cable to allow the three-wheel design to be dispensed with, i.e. a single drive wheel arranged directly opposite the idler wheel is able to provide sufficient traction to the medical device. Only in special cases may it be necessary to use two drive wheels and one idler wheel, or the opposite configuration with two idler wheels and a single drive wheel. Another option is to use two drive wheels and two idler wheels in this case. Secondly, the ratchet mechanism for the clutch has proven not to be sufficiently reliable. Therefore, a third embodiment of the feed device has been developed, as Figure 10-15 shown.

[0063] Figure 10 The figure shows the exterior of the new device. It includes a housing with an input port 1001a for a medical instrument and an output port 1001b for insertion into the instrument channel of an endoscope system. The feeding device also includes a contact member for the drive shaft (not shown) and a rotary button 1012 for operating the clutch. This button can, of course, be replaced by a joystick if desired.

[0064] Figure 11 The interior of the feeder is shown. The drive mechanism includes a worm 1109 meshing with a geared wheel 1108. The worm includes a hexagonal socket 1102 for connection to a drive motor. Wheel 1108 is connected to a shaft 1107 that drives a drive wheel 1103. Opposite drive wheel 1103 is an idler wheel 1110. The idler wheel rotates freely on a spindle 1111. This spindle can be operated by rotating a knob 1012 to shift the idler wheel toward the drive wheel, thereby engaging a medical device passing between the wheels, thereby acting as a clutch.

[0065] Figure 12A cross-sectional view of a feed device showing the arrangement of the clutch mechanism. The rotary button 1012 comprises a hollow stem 1214 which engages with the spindle 1111. The button can slide up and down on the spindle against a first spring 1215 which forces the button upward. The button is adapted to engage with a plurality of notches 1417 ( Figure 14 ) to rotate the spindle. The button includes a circular protrusion 1213, which, when turned, will slide against the conical protrusion on the upper part of the housing, thereby pushing the rotation button 1012 and the rod 1214 downward against the force of the spring 1215. When the button has been turned fully clockwise, the protrusion 1213 will pass over the edge of the conical protrusion and quickly return. It will thus be caught by the protrusion, preventing it from returning unless the button is pressed again, allowing the protrusion to return over the edge. This retaining mechanism is Figure 15 As shown in more detail in FIG, the spindle 1111 is rotated by rotating the button 1012 against the force of the spring 1216, which is engaged with the spindle.

[0066] Figure 13 is the corresponding section of the feed device, which is perpendicular to Figure 12 A cross section is shown. Between drive wheel 1103 and idler wheel 1010, there is a space 1316 aligned with entry door 1001a and exit door 1001b, through which the medical device will pass. It should be noted that the lower portion 1111a of spindle 1111 is eccentric, i.e., mounted offset from the centerline of the main spindle portion 1111b, and extends through an arcuate recess or cutout 1319 in a wall 1320 that traverses the housing of the device.

[0067] Figure 14 The rotary button 1012 is shown in detail. A plurality of notches 1417 are provided in the hollow stem 1214. The stem also includes a circular protrusion 1213.

[0068] Figure 15 The rotary button 1012 is shown mounted in a feed device. The projection 1213 has a rounded portion 1521 adapted to slide against a tapered projection 1522 on the inside of the housing. The figure also shows a rib 1523 on the spindle 1111 which mates with a corresponding recess 1417 ( Figure 14 ) join.

[0069] In all other respects, Figure 10-15 The embodiment of the feed device shown is with Figure 2-5 The first embodiment shown is designed in the same manner as that shown, including the design of the drive wheel and idler wheel and how to operate the device. In addition, the box solution shown in Figures 6-9 can also be included in this embodiment. Figure 10-15The embodiment shown includes only one drive wheel and associated idler wheel, but other configurations having two or more pairs of drive wheels and idler wheels may also be implemented.

Claims

1. An instrument feeding device (201) for use in an endoscope system, for feeding a medical instrument (202) into a body or removing the medical instrument from the body, the instrument feeding device comprising: a connector (302) for connecting the instrument feed device (201) to a motor (203) for moving the medical instrument (202) through the instrument feed device (201); a drive wheel (303) arranged to be driven to rotate by the motor, wherein the drive wheel (303) is positioned on one side of the medical device (202), and an idler wheel (310) is positioned on the opposite side of the medical device relative to the drive wheel (303), a clutch mechanism adapted to push the idler wheel (310) against the medical device (202) and thereby push the medical device (202) against the drive wheel (303) to maintain the idler wheel (310) in an activated position against the medical device (202), the clutch mechanism also being adapted to release the idler wheel from the activated position, Characterized in that the clutch mechanism comprises a rotary button (1012) connected to a main shaft, the main shaft comprising a main portion (1111b) and an eccentric portion (1111a), the eccentric portion (1111a) being arranged to be offset relative to a center line passing through the main portion, wherein the idler gear is rotatably mounted on the eccentric portion of the main shaft, Wherein, the rotating button (1012) includes a rod (1214) which is hollow and slidably mounted on the main part (1111b) of the main shaft, and the rod (1214) includes: a recess (1417) that engages with a corresponding rib (1523) on the main part of the main shaft to allow the rotating button to rotate the main shaft; a protrusion (1213) on the rod that engages with a conical protrusion (1522) on a wall surrounding the device; and a spring (1215) that forces the protrusion against the conical protrusion (1522).

2. The instrument feeding device according to claim 1, wherein: The tapered protrusion (1522) includes an edge on its distal end that will retain the tab (1213) as it passes over the edge.

3. The instrument feeding device according to any one of the preceding claims, wherein The drive wheel and the idler wheel include a rigid plastic core and a soft rubber outer layer, wherein the soft rubber outer layer is molded to the rigid plastic core.

4. The instrument feeding device according to claim 3, wherein: The outer periphery of the soft rubber outer layer is formed with herringbone patterns or tractor tread patterns.

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