阅读说明：本技术 血管支架输送系统 (Vascular stent delivery system ) 是由 吴常生 陆信武 叶开创 葛泉波 包程 施玉峰 于 2021-05-18 设计创作，主要内容包括：本发明提供一种血管支架输送系统,其包括：导管单元,包括外管以及设于外管内的内管单元,内管单元包括内管以及置于内管上的支架推送单元,内管单元与外管间且在支架推送单元前方具有容置血管支架的装载区；输送单元,包括驱动把手、锁紧机构以及置于外壳内的传动单元,传动单元包括转动齿轮组、后驱齿条和前驱齿条,后驱齿条和前驱齿条均与所述转动齿轮组啮合；后驱齿条与驱动把手相连,前驱齿条与外管相连,驱动把手中设有与内管相连的推杆；驱动把手滑动套设于外壳上,锁紧机构设于驱动把手上,用于将驱动把手和外壳锁紧和释放。本发明中使用者仅操作驱动把手即可实现血管支架的输送,便于实现。(The present invention provides a vascular stent delivery system, comprising: the catheter unit comprises an outer tube and an inner tube unit arranged in the outer tube, the inner tube unit comprises an inner tube and a stent pushing unit arranged on the inner tube, and a loading area for accommodating the intravascular stent is arranged between the inner tube unit and the outer tube and in front of the stent pushing unit; the conveying unit comprises a driving handle, a locking mechanism and a transmission unit arranged in the shell, the transmission unit comprises a rotating gear set, a rear driving rack and a front driving rack, and the rear driving rack and the front driving rack are both meshed with the rotating gear set; the rear driving rack is connected with the driving handle, the front driving rack is connected with the outer pipe, and a push rod connected with the inner pipe is arranged in the driving handle; the driving handle is sleeved on the shell in a sliding mode, and the locking mechanism is arranged on the driving handle and used for locking and releasing the driving handle and the shell. According to the invention, the user can realize the conveying of the vascular stent only by operating the driving handle, so that the conveying is convenient to realize.)

1. A vascular stent delivery system, comprising:

the catheter unit comprises an outer tube and an inner tube unit arranged in the outer tube, the inner tube unit comprises an inner tube and a stent pushing unit arranged on the inner tube, and a loading area for accommodating a vascular stent is arranged between the inner tube unit and the outer tube and in front of the stent pushing unit;

the conveying unit comprises a driving handle, a locking mechanism and a transmission unit arranged in the shell; the driving handle is connected with the catheter unit through the transmission unit so as to drive the outer tube and the inner tube to move, and the moving directions of the outer tube and the inner tube are opposite; the driving handle is sleeved on the shell in a sliding mode, and the locking mechanism is arranged on the driving handle and used for locking and releasing the driving handle and the shell.

2. The stent delivery system according to claim 1, wherein: the locking mechanism comprises a pressing sheet, a locking block and a spring, the pressing sheet is rotatably arranged on the driving handle, one end of the pressing sheet is abutted to the locking block, the spring supports the locking block and is used for keeping the locking block to lock the driving handle and the shell, and when the pressing sheet is pressed, the pressing sheet is abutted to the locking block to release the driving handle and the shell.

3. The stent delivery system according to claim 1, wherein: the transmission unit comprises a rotating gear set, a rear drive rack and a front drive rack, and the rear drive rack and the front drive rack are both meshed with the rotating gear set; the rear drive rack is connected with the drive handle, the front drive rack is connected with the outer tube, and a push rod connected with the inner tube is fixedly arranged in the drive handle.

4. The stent delivery system according to claim 3, wherein: the rotating gear set comprises a rotating shaft, a first gear and a second gear, the rotating shaft is rotatably arranged in the shell, the first gear and the second gear are arranged on the rotating shaft, the first gear is meshed with the rear drive rack, and the second gear is meshed with the front drive rack.

5. The stent delivery system according to claim 4, wherein: the gear ratios of the first gear and the second gear are different.

6. The stent delivery system according to claim 4, wherein: the first gear or the second gear is matched with the rotating shaft through a one-way clutch mechanism, and the front driving rack is not moved when the driving handle drives the rear driving rack to move backwards.

7. The stent delivery system according to claim 1, wherein: the push rod and the inner tube are both of hollow structures and communicated with each other, a via hole communicated with the push rod is formed in the driving handle, and the front end of the inner tube is connected with a soft head.

8. The stent delivery system according to claim 1, wherein: the transmission unit comprises a rotating gear set, a rear driving rack, a front driving rack and a middle driving rack, the rotating gear set comprises a rotating shaft which is rotatably arranged in the shell, a first gear, a second gear and an intermediate gear, the first gear, the second gear and the intermediate gear are arranged on the rotating shaft, the first gear is meshed with the rear driving rack, the second gear is meshed with the front driving rack, and the intermediate gear is connected with the middle driving rack; the middle driving rack is connected with the driving handle, the front driving rack is connected with the outer tube, and a push rod connected with the inner tube is fixedly arranged in the driving handle.

9. The stent delivery system according to claim 8, wherein: the first gear or the second gear is matched with the rotating shaft through a one-way clutch mechanism, when the driving handle drives the middle driving rack to move backwards, the rear driving rack moves backwards simultaneously, but the front driving rack does not move.

10. The stent delivery system according to claim 1, wherein: the transmission unit includes rotation gear group, back drive rack and front drive rack, rotation gear group is located including rotating the axis of rotation in the shell and locating epaxial single gear rotates, one side of single gear with back drive rack meshes mutually, the opposite side of single gear with the indirect or direct looks meshing of front drive rack.

11. The stent delivery system according to claim 1, wherein: the catheter unit also comprises a hollow tube arranged in the inner tube, the hollow tube is fixedly connected with the shell, and the front end of the hollow tube is connected with a soft head.

12. The stent delivery system according to claim 1, wherein: the support pushing unit is one or more groups of clamping jaws arranged around the circumferential direction of the inner pipe.

13. The stent delivery system according to claim 1, wherein: the support pushing unit is in a circular tube shape or a plum blossom shape.

Technical Field

The invention relates to the technical field of medical instruments, in particular to a conveying system of a blood vessel stent.

Background

For example, peripheral vascular stent intervention requires the use of a delivery device for implantation, and in the prior art, for example, CN201110190183.4 discloses a delivery device which adopts a hollow inner tube and an outer tube that are sleeved with each other, wherein the vascular stent is arranged between the inner tube and the outer tube, the inner tube is a hollow structure, and an inner lumen thereof is convenient for a guide wire to penetrate during surgery; during operation, the catheter unit is conveyed to an operation area by the conveying device under the guidance of the guide wire, the control unit enables the outer tube and the inner tube to move relatively, and the intravascular stent is unfolded and clings to the inner wall of the blood vessel to play a supporting role.

The axial length of the stent in the human body lumen is marked as L1, the axial length of the stent in the compressed state in the outer tube is marked as L2, and L1 is generally smaller than L2, so the ratio of the length difference of the two to L2 is called the stent foreshortening ratio. With respect to the delivery and release of the self-expanding stent disclosed in CN201110190183.4, when the stent has a short shrinkage rate of zero or less (e.g., less than 3%) in the human body lumen, there is generally no problem in the positioning and release of the stent. However, for stents with large shrinkage, especially for high-shrinkage stents (30% or more) braided with ni-ti wires, the above-mentioned release method has many drawbacks, 1): the simple releasing mode can not ensure that the actual positions of the positioning point of the bracket before releasing and the positioning point of the bracket after releasing are matched, so that the far end of the bracket is displaced. Assuming that the length of the stent in the compressed state inside the outer tube is L0 and the actual natural length released into the predetermined lumen is L1, the amount of axial stent shortening is Δ L0-L1. Because the stent is required to be axially shortened when released, and the proximal end of the stent is still compressed in a sheath of the conveying device when the stent is not completely released and cannot move, the positioning point at the distal end of the stent can move towards the proximal end along with the shortening of the stent, and after the release of the stent is completed, the moving distance of the positioning point at the distal end can reach delta L, so that the positioning of the stent is inaccurate, great troubles are brought to the operation, and even the operation fails. 2): because the stent is shortened axially during the release process, the attached distal stent portion will gradually move proximally (or have a tendency to move) in the human body lumen as the stent is shortened, and the movement will most likely cause damage to the inner wall of the lumen. In addition, in the process of releasing the stent, because the far end and the near end of the stent are respectively limited by the inner wall of the lumen of the human body and the conveying device, the stent which is not completely shortened has an axial stretching effect, so that an axial acting force exists between the stent and the inner wall of the lumen of the human body, and the inner wall of the lumen is extremely easy to be damaged by the dragging force.

Since the stent shrinks during the release process, the delivery device cannot automatically adjust to this shrinkage. And CN201110183029.4 discloses a self-adaptive delivery device for stent shortening, the delivery device designed by the patent can accurately release the stent, no displacement exists between the stent and the lumen, and the damage of the stent to the lumen of a human body can be avoided. However, the conveying device has a complex structure and large transmission force, a long operating handle is required for a long-specification support, the conveying device is very heavy, and the knob driving force is large, so that great inconvenience is brought to the operation of a doctor.

Therefore, there is a need for a vascular stent delivery system having a stent foreshortening adaptive function, and which is simple in structure and easy to operate.

Disclosure of Invention

In view of the above-mentioned shortcomings of the prior art, the present invention aims to provide a blood vessel stent delivery system, which is used for solving the problems of complex and difficult operation of the blood vessel stent delivery mechanism in the prior art.

To achieve the above and other related objects, the present invention provides a stent delivery system, comprising:

the catheter unit comprises an outer tube and an inner tube unit arranged in the outer tube, the inner tube unit comprises an inner tube and a stent pushing unit arranged on the inner tube, and a loading area for accommodating a vascular stent is arranged between the inner tube unit and the outer tube and in front of the stent pushing unit;

the conveying unit comprises a driving handle, a locking mechanism and a transmission unit arranged in the shell; the driving handle is connected with the catheter unit through the transmission unit so as to drive the outer tube and the inner tube to move, and the moving directions of the outer tube and the inner tube are opposite; the driving handle is sleeved on the shell in a sliding mode, and the locking mechanism is arranged on the driving handle and used for locking and releasing the driving handle and the shell.

Preferably, the locking mechanism comprises a pressing piece, a locking block and a spring, the pressing piece is rotatably arranged on the driving handle, one end of the pressing piece is abutted to the locking block, the spring supports the locking block and is used for keeping the locking block to lock the driving handle and the shell, and when the pressing piece is pressed, the pressing piece is abutted to the locking block to release the driving handle and the shell.

Preferably, the transmission unit comprises a rotating gear set, a rear driving rack and a front driving rack, and the rear driving rack and the front driving rack are both meshed with the rotating gear set; the rear drive rack is connected with the drive handle, the front drive rack is connected with the outer tube, and a push rod connected with the inner tube is fixedly arranged in the drive handle.

Preferably, the rotating gear set comprises a rotating shaft arranged in the housing, and a first gear and a second gear which are arranged on the rotating shaft, wherein the first gear is meshed with the rear drive rack, and the second gear is meshed with the front drive rack.

Preferably, the gear ratios of the first gear and the second gear are different.

Preferably, the first gear or the second gear is matched with the rotating shaft through a one-way clutch mechanism, and the front driving rack is not moved when the driving handle drives the rear driving rack to move backwards.

Preferably, the push rod and the inner tube are both of hollow structures and communicated with each other, a via hole communicated with the push rod is formed in the driving handle, and the front end of the inner tube is connected with a soft head.

Preferably, the transmission unit includes a rotation gear set, a rear drive rack, a front drive rack and a middle drive rack, the rotation gear set includes a rotation shaft rotatably disposed in the housing, a first gear, a second gear and an intermediate gear disposed between the first gear and the second gear, the first gear is engaged with the rear drive rack, the second gear is engaged with the front drive rack, and the intermediate gear is connected with the middle drive rack; the middle driving rack is connected with the driving handle, the front driving rack is connected with the outer tube, and a push rod connected with the inner tube is fixedly arranged in the driving handle.

Preferably, the first gear or the second gear is matched with the rotating shaft through a one-way clutch mechanism, and when the driving handle drives the middle driving rack to move backwards, the rear driving rack moves backwards simultaneously, but the front driving rack does not move.

Preferably, the transmission unit includes a rotation gear set, a rear drive rack and a front drive rack, the rotation gear set includes a rotation shaft arranged in the housing and a single gear arranged on the rotation shaft, one side of the single gear is engaged with the rear drive rack, and the other side of the single gear is engaged with the front drive rack indirectly or directly.

Preferably, the catheter unit further comprises a hollow tube arranged in the inner tube, the hollow tube is fixedly connected with the outer shell, and the front end of the hollow tube is connected with a soft head.

Preferably, the support pushing unit is one or more groups of clamping jaws arranged around the circumferential direction of the inner pipe.

Preferably, the stent pushing unit is in a shape of a circular tube or a plum blossom.

The part is correspondingly modified after the claims are determined to be correct

As described above, the vascular stent delivery system of the present invention has the following advantageous effects: the driving handle is enabled to reciprocate relative to the shell by unlocking the driving handle, so that the rear driving rack and the push rod are driven to move, the inner pipe moves forwards and the outer pipe moves backwards, and the intravascular stent positioned at the loading area is pushed out and positioned by the stent pushing unit; the user only operates the driving handle to realize the conveying of the blood vessel stent, which is convenient to realize.

Drawings

Fig. 1 shows an overall schematic view of a vascular stent delivery system of the present invention.

Fig. 2 is a schematic view of an embodiment of the inner tube unit of the present invention.

Fig. 3 is a schematic view showing another embodiment of the inner tube unit in the present invention.

Fig. 4 shows a schematic view of a delivery unit of the present invention.

Fig. 5 is a schematic view of a rotary gear set of the present invention.

Fig. 6 is a schematic view of the driving handle of the present invention.

Description of the element reference numerals

10 catheter unit

11 inner pipe unit

20 drive unit

30 rotating gear set

40 drive handle

100 soft head

110 connecting pipe

120 support pushing unit

130 claw

140 inner pipe

150 outer tube

210 outer pipe joint

220 front driving rack

230 rear-drive rack

240 push rod

250 gear clamping groove

300 rotation axis

310 first gear

320 second gear

410 pressing tablet

420 locking block

430 spring

440 connecting block

Detailed Description

The following description of the embodiments of the present invention is provided for illustrative purposes, and other advantages and effects of the present invention will become apparent to those skilled in the art from the present disclosure.

Please refer to fig. 1 to 6. It should be understood that the structures, ratios, sizes, and the like shown in the drawings are only used for matching the disclosure of the present disclosure, and are not used for limiting the conditions that the present disclosure can be implemented, so that the present disclosure is not limited to the technical essence, and any structural modifications, ratio changes, or size adjustments should still fall within the scope of the present disclosure without affecting the efficacy and the achievable purpose of the present disclosure. In addition, the terms "upper", "lower", "left", "right", "middle" and "one" used in the present specification are for clarity of description, and are not intended to limit the scope of the present invention, and the relative relationship between the terms and the terms is not to be construed as a scope of the present invention.

For convenience of description, the axial direction of the catheter unit is referred to as the front-rear direction, the end closer to the user (i.e., where the handle is rotated) is referred to as the rear or proximal end, and the end farther from the user is referred to as the front or distal end.

Example 1

As shown in fig. 1 to 6, the present invention provides a stent delivery system, comprising:

the catheter unit 10 comprises an outer tube 150 and an inner tube unit 11 arranged in the outer tube, wherein the inner tube unit 11 comprises an inner tube 140 and a stent pushing unit 120 arranged on the inner tube 140, and a loading area for accommodating a vascular stent is arranged between the inner tube unit 11 and the outer tube 150 and in front of the stent pushing unit 120;

the conveying unit comprises a driving handle 40, a locking mechanism and a transmission unit 20 arranged in the housing, wherein the transmission unit 20 comprises a rotating gear set 30, a rear driving rack 230 and a front driving rack 220, the rear driving rack 230 and the front driving rack 220 are both meshed with the rotating gear set 30, and the moving directions of the rear driving rack 230 and the front driving rack 220 are opposite; the rear driving rack 230 is connected with the driving handle 40, the front driving rack 220 is connected with the outer tube 150, and a push rod 240 connected with the inner tube of the inner tube unit 11 is fixedly arranged in the driving handle 40 in a penetrating way; the driving handle 40 is slidably sleeved on the housing, and the locking mechanism is arranged on the driving handle 40 and used for locking and releasing the driving handle 40 and the housing.

In this embodiment, the driving handle 40 and the housing are locked and released by a locking mechanism, and a user only needs to unlock the locking mechanism, then, the driving handle 40 is pushed and pulled back and forth, the reverse movement of the inner tube unit 11 and the outer tube 150 can be realized, that is, the forward movement of the inner tube unit 11 drives the stent pushing unit 120 to push the blood vessel stent out of the catheter unit 10, the outer tube 150 moves backward, i.e. moves proximally, so as to complete the release of the stent, and in the release process of the stent of the present embodiment, the driving handle 40 drives the outer tube 150 to move backward through the transmission unit, namely, the outer tube 150 moves backwards, and simultaneously the driving handle 40 drives the inner tube unit 11 to move forwards all the time, so that the released blood vessel stent can be attached to the blood vessel wall in time, and the problem that the released blood vessel stent cannot be attached to the wall in time due to the fact that the outer tube 150 is pulled towards the near end side simply and the released blood vessel stent is pulled by the conveying device is solved; further, since the driving force of the rotary knob is directly transmitted to the inner tube unit 11 and then transmitted to the outer tube 150 through the transmission gear set, the driving force required is small, and thus the operation is convenient.

For the convenience of operation, as shown in fig. 4 and 6, the locking mechanism in this embodiment includes a pressing plate 410, a locking block 420 and a spring 430, the pressing plate 410 is rotatably disposed on the driving handle 40, one end of the pressing plate 410 abuts against the locking block 420, the spring 430 supports the locking block 420 for keeping the locking block 420 locking the driving handle 40 and the housing, and the pressing plate 410 presses the locking block 420 to release the driving handle 40 and the housing when the pressing plate 410 is pressed. The unlocking can be realized only by pressing, and the operation is easy; when the driving handle 40 does not need to be pushed or pulled, the locking block 420 locks the driving handle 40 and the shell under the elastic force of the spring 430, so that misoperation is avoided, and the safety and practicability of the conveying system are improved.

A specific embodiment of the locking block 420 for locking the driving handle 40 and the housing in this embodiment may be: the driving handle 40 is provided with a clamping groove, the locking block 420 is connected with the shell, when the pressing sheet 410 is not pressed, the locking block 420 is jacked and clamped in the clamping groove by the spring 430, when the pressing sheet 410 is pressed, the spring 430 is compressed, the locking block 420 descends to be separated from the clamping groove, the driving handle 40 and the shell are unlocked, and the driving handle 40 can be pushed and pulled by pressing the pressing sheet.

The locking mechanism is not limited to the above, and may be other clutch mechanisms, and only needs to be able to lock and unlock the driving handle and the housing under operation.

In order to control the pushing speed and reduce the driving force of the push-pull driving handle 40, as shown in fig. 5, the rotating gear set 30 in this embodiment includes a rotating shaft 300 rotatably disposed in the housing, and a first gear 310 and a second gear 320 disposed on the rotating shaft 300, wherein the first gear 310 is engaged with the rear driving rack 230, and the second gear 320 is engaged with the front driving rack 220. Further, the gear ratio of the first gear 310 and the second gear 320 is different. In this embodiment, the rear driving rack 230 and the front driving rack 220 are disposed in parallel and staggered, and the teeth on the rear driving rack 230 and the front driving rack 220 face opposite directions.

The stent pushing unit 120 in the inner tube unit 11 may be a tube segment with a plurality of circumferentially arranged claws 130, as shown in fig. 3, which may also be provided with one claw; it may also be in the shape of a circular tube with a diameter larger than that of the inner tube, as shown in FIG. 2, or in other convex shapes, such as plum blossom shape; the stent pushing unit 120 in this embodiment does not pull the stent when moving proximally.

In this embodiment, the inner tube unit 11 can be divided into multiple sections along the back-to-back direction, the main section is the inner tube 140, the proximal end of the inner tube 140 is connected to the push rod 240, the inner tube 140 and the push rod 240 are both hollow structures and communicated with each other in this embodiment, the driving handle is provided with a via hole communicated with the push rod 240, the distal end of the inner tube 140 can be connected to a soft head 100 through a connecting tube 110, in this embodiment, a guide wire can penetrate into the inner tube unit 11, the guide catheter unit 10 can be guided into an operation area, and the soft head can be arranged to prevent the inner tube 140 from extending out of the outer tube and then stabbing the blood vessel wall.

Example 2

The stent delivery system of this embodiment has a similar structure to that of embodiment 1, except that the catheter unit 10 of embodiment 1 only includes the inner tube unit 11 and the outer tube 150, the inner tube unit 11 is a hollow lumen for passing a guide wire during surgery, and the guide wire guides the catheter unit 10 into the surgical field. The catheter unit 10 in this embodiment may further include a hollow tube disposed in the inner tube unit 11, the hollow tube is inserted into the inner tube and can move relative to the inner tube, and is fixedly connected to the housing, the front end of the hollow tube is connected to a soft head, and by adding the hollow tube, the guide wire passes through the hollow tube to guide the catheter unit, so that the hollow tube and the soft head are fixed during the operation, and the driving handle 40 only drives the inner tube and the outer tube to move, thereby reducing the loss to the vascular wall.

Example 3

In order to adapt to vascular stents with different lengths, as shown in fig. 4, in this embodiment, on the basis of the above embodiments 1 and 2, the gear slot 250 is arranged on the inner wall of the housing, and the external protrusion is arranged on the rear drive rack 230, so that the rear drive rack 230 is locked conveniently by the cooperation of the external protrusion and the gear slot 250, the movement distance of the rear drive rack is known, and a user can judge whether the vascular stent is pushed to the position conveniently.

The blood vessel stent conveying system of the embodiment has the specific structure that: the outer tube 150 is connected to the front drive rack 220 by an outer tube coupling 210, the end of the inner tube 140 extends into the housing and is connected to the push rod 240, and both the push rod 240 and the rear drive rack 230 are connected to a connecting block 440 in the drive handle 40.

During operation, a guide wire penetrates through a hollow tube in the catheter unit 10, if no hollow tube exists, the guide wire directly penetrates into an inner tube, the pressing piece 410 is pressed, the driving handle 40 and the shell are unlocked, the driving handle 40 is pushed forwards, the driving handle 40 drives the rear driving rack 230 to move forwards, the rear driving rack 230 drives the front driving rack 220 to move backwards through the rotating gear set 30, the front driving rack 220 drives the outer tube 150 to move backwards, meanwhile, the driving handle 40 pushes the inner tube unit 11 to move forwards through the push rod 240, and the stent pushing unit 120 in the inner tube unit 11 pushes the vascular stent out of the catheter unit 10, so that release of the vascular stent is achieved. In this embodiment, the moving speed ratio of the driving handle 40 to the front driving rack 220 can be equal to the ratio of the axial shortening of the delivered stent to the natural length of the stent, so as to further avoid the influence of the axial expansion of the stent on the vascular wall.

Example 4

On the basis of the three embodiments, the driving handle can reciprocate in the operation, so that the vascular stents with different specifications can be released adaptively, and the shell does not need to be enlarged even if the vascular stents with large specifications are large. In this embodiment, the first gear or the second gear is engaged with the rotating shaft through the one-way clutch mechanism, and when the driving handle drives the rear driving rack to move backward, the front driving rack is not moved.

Example 5

The transmission unit in the above embodiment may be replaced by a structure form that the transmission unit includes a rotation gear set, a rear drive rack, a front drive rack and a middle drive rack, the rotation gear set includes a rotation shaft rotatably disposed in the housing, a first gear, a second gear and an intermediate gear disposed between the first gear and the second gear, the first gear is engaged with the rear drive rack, the second gear is engaged with the front drive rack, and the intermediate gear is connected with the middle drive rack; the middle driving rack is connected with the driving handle, the front driving rack is connected with the outer pipe, and a push rod connected with the inner pipe is fixedly arranged in the driving handle. The transmission unit of this embodiment it has add well rack and the intermediate gear of driving, realizes the transmission between drive handle and the rotating gear group, is convenient for arrange the installation.

Preferably, the first gear or the second gear in this embodiment is engaged with the rotating shaft through a one-way clutch mechanism, and when the driving handle drives the middle driving rack to move backward, the rear driving rack moves backward at the same time, but the front driving rack does not move.

As another embodiment of the transmission unit, it may further include a rotation gear set, a rear drive rack, and a front drive rack, where the rotation gear set includes a rotation shaft rotatably disposed in the housing and a single gear disposed on the rotation shaft, one side of the single gear is engaged with the rear drive rack, and the other side of the single gear is indirectly or directly engaged with the front drive rack. The single gear in this embodiment may be a unidirectional rotation gear, which is engaged with the front drive rack through a clutch mechanism, and when the driving handle drives the middle drive rack to move backward, the rear drive rack moves backward at the same time, but the clutch mechanism acts to release the engagement between the front drive rack and the single gear. The single gear in this embodiment may also be a bi-directional rotating gear that directly engages the front drive rack and the rear drive rack moves in the opposite direction simultaneously as the drive rack moves back and forth in the drive handle.

Therefore, the invention effectively overcomes various defects in the prior art and has high industrial utilization value.

The foregoing embodiments are merely illustrative of the principles and utilities of the present invention and are not intended to limit the invention. Any person skilled in the art can modify or change the above-mentioned embodiments without departing from the spirit and scope of the present invention. Accordingly, it is intended that all equivalent modifications or changes which can be made by those skilled in the art without departing from the spirit and technical spirit of the present invention be covered by the claims of the present invention.