CN111759325B

CN111759325B - Disposable safety blood taking needle

Info

Publication number: CN111759325B
Application number: CN202010676602.4A
Authority: CN
Inventors: 胡超宇
Original assignee: Puang Hangzhou Medical Technology Co ltd
Current assignee: Puang Hangzhou Medical Technology Co ltd
Priority date: 2020-07-14
Filing date: 2020-07-14
Publication date: 2021-05-11
Anticipated expiration: 2040-07-14
Also published as: CN111759325A

Abstract

The invention relates to the technical field of medical instruments, and particularly discloses a disposable safety blood taking needle which at least comprises a shell, a needle core, a needle cap, an inner sleeve, a driving spring and a retraction spring, wherein the inner sleeve is provided with a first position and a second position relative to the shell, and the driving spring is positioned between the needle core and the shell and has a first pre-tightening state; the needle core is provided with a pair of first steps which are oppositely arranged and face one side of the needle cap, the inner sleeve is provided with a pair of first elastic arms which are oppositely arranged, and the first elastic arms are provided with second steps which are used for being abutted against the first steps; a separating mechanism is arranged in the shell. The driving spring has multiple functions, and in the process of compressing the inner sleeve, the force required for triggering the ejection of the stylet is larger because the elastic force of the driving spring is overcome and the driving spring is compressed, so that the stylet can be prevented from being triggered by mistake due to smaller force under the unconscious condition; the structural design concept is ingenious, and the state of whether the stylet is ejected or not is judged accurately.

Description

Disposable safety blood taking needle

Technical Field

The invention relates to the technical field of medical instruments, in particular to a disposable safety blood taking needle.

Background

A disposable safety lancet is a commonly used medical device for rapidly puncturing the skin of a patient to take blood from the patient.

In the prior art, the disposable safety blood taking needle has more structural forms, more complex structures and higher cost. The invention discloses a simple safety blood taking needle with the publication number of CN210433488U, which comprises a shell, a spring, a needle core, a needle cap and an inner sleeve. Then, the inner sleeve is pressed to move relative to the outer shell and move until the locking of the needle core is released, and the energy-storage spring ejects the needle core until the needle tip is exposed and punctures the skin of a patient.

In the structure, the position of the needle core is changed and cannot be restored, and the plastic part at the joint of the needle core and the needle cap is broken, so that the mark that the blood taking needle is used is made. The used needle core can be replaced unless the shell is damaged, so that the needle core can be used as a disposable blood taking needle to avoid the phenomena of cross use and secondary processing.

However, the simple safety blood taking needle with the above structure has certain defects, which are as follows:

(1) because the retraction spring is not arranged, after the needle core is ejected, the action that the needle point retracts into the inner sleeve is still finished by the retraction of the same spring, one of the defects of the structure is that the needle point can vibrate in a reciprocating way, because the reciprocating motion is finished in a very short time, the finger can be punctured for many times, the pain is obvious, and the wound becomes large or more; another drawback is that the two ends of the spring need to be fixed with the housing and the stylet respectively to achieve the function of needle retraction, but the fixation of the spring and the inside of the housing is very complicated in assembly, and cannot be directly fixed, and usually an auxiliary connecting structure or an adhesive form is needed, so that the assembly is complex and the assembly efficiency is low.

(2) After the installation, the spring just keeps in energy storage state, lacks the relation of connection between endotheca and spring and the nook closing member, before triggering nook closing member ejection, presses the process of endotheca, experiences and feels relatively poor, and the endotheca is pressed the back and does not press under the condition that targets in place, and the position of endotheca can not give birth to the change, therefore, when the endotheca did not press the condition that targets in place, because the position has changed, the user can't distinguish the nook closing member and whether triggered.

(3) During transportation or transfer, the position of the inner sleeve can change due to vibration, and the stylet can be triggered under the condition of relatively large vibration amplitude.

(4) The in-process of needle cap and the rotatory separation of nook closing member, the axial position of needle cap can not change, is twisted off the back until the junction, needs the operator to rotate the needle cap to certain angle, and the needle cap just can be taken out from the blood sampling hole, complex operation, time-consuming, and the convenience is relatively poor.

Disclosure of Invention

The invention aims to solve the technical problem of solving the corresponding technical defects of the simple and safe blood taking needle in the prior art.

In order to solve the technical problems, the technical scheme provided by the invention is as follows: a disposable safety blood taking needle at least comprises a shell, a needle core, a needle cap, an inner sleeve, a driving spring and a retraction spring, wherein a connecting structure which is easy to break is arranged between the needle core and the needle cap, the retraction spring is positioned between the needle core and the inner sleeve, the inner sleeve has a first position and a second position relative to the shell, a first limiting structure is arranged between the needle cap and the inner sleeve, the driving spring is positioned between the needle core and the shell and has a first pre-tightening state, and the elastic pre-tightening force of the driving spring in the first pre-tightening state is transmitted to the inner sleeve through the needle core, the needle cap and the first limiting structure in sequence and drives the inner sleeve to be kept at the first position;

the needle core is provided with a pair of first steps which are oppositely arranged and face one side of the needle cap, the inner sleeve is provided with a pair of first elastic arms which are oppositely arranged, the first elastic arms are provided with second steps which are used for being abutted to the first steps, when the driving spring is in a first pre-tightening state, the first steps and the second steps are in a separated state, and after the first pre-tightening state of the driving spring is released, the needle core moves to the state that the first steps are abutted to the second steps;

the separation mechanism is arranged in the shell and used for opening the first elastic arm and driving the second step to be separated from the first step, the inner sleeve drives the needle core to compress the driving spring to a transmitting energy storage state through the second step and the first step in the process that the inner sleeve moves from the first position to the second position, and the separation mechanism gradually opens the first elastic arm and drives the second step to be separated from the first step when the driving spring is in the transmitting energy storage state.

In a preferred embodiment, a blood sampling hole is formed in the bottom of the inner sleeve, the blood sampling hole has a certain length and a certain width, the first limiting structure comprises a pair of oppositely arranged protrusions arranged on the needle cap and a groove arranged at the bottom of the inner sleeve and matched with the protrusions, and the maximum distance between the pair of protrusions is larger than the width of the blood sampling hole and smaller than the length of the blood sampling hole.

In a preferred embodiment, the inner sleeve is provided at opposite sides thereof with second elastic arms extending obliquely to one side of the housing, and free ends of the second elastic arms are provided with fifth steps.

In a preferred embodiment, the opposite side of the inner wall of the housing is provided with a third step adapted to abut against the fifth step when the inner jacket is in the first position.

In a preferred embodiment, the opposite side of the housing is further provided with fourth steps adapted to abut against the fifth steps when the inner sleeve is in the second position, the distance between the fourth steps is greater than the distance between the third steps, and the fourth steps are provided with through grooves penetrating through the housing wall.

In a preferred embodiment, a side of the separating means facing the first resilient arm is provided with a ramp.

In a preferred embodiment, a first spring chamber for mounting a drive spring is provided in the housing, and a second spring chamber for mounting a retraction spring is provided in the inner sleeve.

In a preferred embodiment, a first guide mechanism is arranged between the inner sleeve and the shell, and the first guide mechanism comprises a second elastic arm and a first guide groove arranged on the inner wall of the shell and matched with the second elastic arm.

In a preferred embodiment, a second guiding mechanism is disposed between the stylet and the housing, and the second guiding mechanism includes a pair of guiding blocks oppositely disposed on the stylet and a second guiding groove disposed on an inner wall of the housing and adapted to the guiding blocks.

In a preferred embodiment, a third guiding mechanism is further disposed between the stylet and the housing, the third guiding mechanism comprising: the first step is arranged on the lug; and a cross-shaped guide groove matched with the cross-shaped structure in the separating mechanism.

The disposable safety blood taking needle of the embodiment has the working principle that the driving spring is in a first pre-tightening state in an initial state, and the shell, the needle core, the needle cap and the inner sleeve form a whole body with a connection relation through the pre-tightening elastic force generated by the first pre-tightening state of the driving spring. When the blood sampling needle is used, the needle cap is rotated by a certain angle, the first limiting structure is separated from contact due to the release of the elastic pretightening force, the protrusion on the needle cap extends out of the blood sampling hole, at the moment, the first step of the needle core and the second step of the inner sleeve enter an abutting state from a separating state, and the inner sleeve, the needle core, the driving spring and the shell form a whole with a connection relation; then, the needle cap can be freely rotated until the needle cap is twisted off from the needle core; in the using process, the inner sleeve is pressed to move from the first position to the second position, the needle core is driven to compress the driving spring through the second step and the first step, the spring is in a launching energy storage state, in the moving process, the separating mechanism gradually stretches the first elastic arm, the first step is separated from the second step when the driving spring is in the launching energy storage state, the needle core is ejected under the releasing action of the elastic potential energy of the driving spring, the needle point penetrates through the blood sampling hole to prick the skin, and after the needle core is launched, the inner sleeve is kept at the second position; after the needle core is ejected, the retraction spring is compressed, and after the acupuncture is finished, the needle tip returns into the inner sleeve under the recovery action of the retraction spring, so that the exposure of the needle tip is effectively prevented.

Compared with the prior art, the disposable safety blood taking needle of the embodiment has the following beneficial effects:

(1) the driving spring has multiple functions, and the first function is that each part is kept in an initial state through elastic pretightening force in the initial state and has a connection relationship to form a whole; the second function is as a driving source for ejecting the stylet; the third function is that the inner sleeve has damping in the compression process of the inner sleeve, so that the use experience of a user is better; the fourth function is that under the condition that the inner sleeve is not compressed in place, the inner sleeve can recover under the action of the driving spring, so that a user can easily judge whether the stylet is triggered; the fifth important role is that in the transportation or transfer process, when the position of the inner sleeve changes due to vibration, the elastic pretightening force can drive the inner sleeve to recover to the first position, and the stylet can be prevented from being triggered.

(2) In the process of compressing the inner sleeve, the elastic force of the driving spring is overcome and the driving spring is compressed, so that the force required for triggering the ejection of the stylet is larger, and the stylet can be prevented from being triggered by mistake due to smaller force under the unconscious condition.

(3) The inner sleeve is pressed simply, but the simple operation enables a plurality of actions such as the movement of the inner sleeve, the compression of the needle core on the driving spring, the expansion of the separating mechanism on the first elastic arm and the like to be carried out synchronously, the design concept is ingenious, and the state of whether the needle core is ejected or not is judged accurately.

(4) The number of parts is less, when the needle is assembled, the driving spring is firstly arranged in the first spring cavity, then the needle core is arranged, the retraction spring is sleeved on the needle cap, finally the inner sleeve is arranged, the inner sleeve is pressed into the first position, and then the assembly is completed.

(5) In the needle cap separation process, after the needle cap rotates for a certain angle, the protrusion of the first limiting structure can be separated from the length direction of the blood sampling hole under the action of the elastic pre-tightening force of the driving spring, at the moment, the protrusion is positioned outside the inner sleeve, the needle cap is rotated in any direction, so that the needle cap can be easily separated from the needle core after being broken from the joint, the needle cap does not need to be taken out at an alignment angle, and the convenience in operation is obviously improved.

(6) Two groups of guide mechanisms are arranged between the stylet and the shell, the guide mechanisms are respectively a second guide mechanism and a third guide mechanism, particularly, the third guide mechanism is a cross-shaped guide mechanism, the centrality of the stylet is kept better in the launching process, the pain of a patient is lower in the process of puncture, and the comfort level is better.

Drawings

FIG. 1 is a schematic view showing an external structure of a disposable safety lancet of this embodiment in a state I (initial state);

FIG. 2 is a schematic cross-sectional view of the disposable safety lancet shown in FIG. 1;

FIG. 3 is a schematic view of an external structure of the housing according to the present embodiment;

FIG. 4 is a schematic view of the internal structure of the housing in this embodiment;

FIG. 5 is a bottom view of the housing of this embodiment;

FIG. 6 is a schematic sectional view of the housing in this embodiment;

FIG. 7 is a front view of the housing shown in FIG. 6;

FIG. 8 is a schematic view of the outer structure of the inner sleeve in this embodiment;

FIG. 9 is a front view of the inner sleeve of FIG. 8;

FIG. 10 is a top view of the inner sleeve shown in FIG. 8;

FIG. 11 is a schematic structural view of the inner sleeve shown in FIG. 8;

FIG. 12 is a schematic view showing the structure of the hub and the cap in the present embodiment;

FIG. 13 is a schematic view of the structure of the core in this embodiment;

FIG. 14 is an external view of the disposable safety lancet of this embodiment in state II;

FIG. 15 is a cross-sectional schematic view of the disposable safety lancet shown in FIG. 14;

FIG. 16 is a schematic sectional view showing the safety lancet of the present embodiment in state III;

FIG. 17 is a schematic sectional view showing the structure of the disposable safety lancet of this embodiment in state IV;

FIG. 18 is a cross-sectional view of the disposable safety lancet of this embodiment in state V;

FIG. 19 is a schematic sectional view showing the structure of the disposable safety lancet of this embodiment in state VI.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is described in further detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

In the description of the present invention, it is to be understood that the terms "upper", "lower", "front", "rear", "inner", "outer", and the like, indicate orientations or positional relationships based on the orientations or positional relationships shown in the drawings, are only for convenience in describing the present invention and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and thus, should not be construed as limiting the present invention.

In the description of the present invention, it should be noted that, unless otherwise explicitly specified or limited, the terms "mounted," "connected," and "connected" are to be construed broadly, e.g., as being fixedly connected, integrally connected, or detachably connected; may be communication within two elements; they may be directly connected or indirectly connected through an intermediate, and those skilled in the art will understand the specific meaning of the above terms in the present invention in specific situations.

As shown in fig. 1 and 2, the disposable safety lancet of the present embodiment includes a housing 10, an inner sheath 20, a core 30, a cap 40, a driving spring 50, and a retraction spring 60.

The housing 10 of this embodiment is constructed as shown in fig. 3-7, and is provided with a first spring chamber 11 at the top for accommodating the driving spring 50, wherein the driving spring 50 is installed in the first spring chamber 11, and the top end of the needle core 30 is located in the first spring chamber 11 in the initial state and is in direct contact with the driving spring 50.

In this embodiment, as shown in fig. 4-7, the housing 10 is provided with a separating mechanism inside, which comprises four separating portions 12 surrounding the outlet of the first spring chamber 11. The outer side of the separation 12 remote from the first spring chamber 11 is provided with a bevel 13.

In the present embodiment, as shown in fig. 4 and 5, the gaps between the four separating portions 12 form a cross-shaped guide groove 111.

In this embodiment, as shown in fig. 4-7, the opposite side walls of the housing 10 are provided with second guide grooves 16, and the second guide grooves 16 are adapted to the corresponding guide grooves of the cross-shaped guide groove 111. Preferably, in this embodiment, two guide ribs 17 are disposed on the side wall of the housing 10, and extend along the length direction of the housing, and a second guide groove 16 is formed between the two guide ribs 17.

In this embodiment, as shown in fig. 4 and 5, the other two opposite side walls of the housing 10 are provided with first guide grooves 19. Preferably, in the present embodiment, the side wall of the housing provided with the first guide groove 19 is provided with a rib 110 protruding outward, and the inner side of the rib 110 forms the first guide groove 19 of the present embodiment.

In this embodiment, as shown in fig. 6 and 7, a third step 14 and a fourth step 15 are disposed on the inner wall of the first guide groove 19, wherein the third step 14 is close to the opening side of the housing 10, and the fourth step 15 is close to the first spring chamber 11. Preferably, the distance between the pair of fourth steps 15 is greater than the distance between the pair of third steps 14. Preferably, in the present embodiment, as shown in fig. 3, a through groove 18 penetrating through the housing wall is provided at the fourth step 15, and the through groove 18 is provided for facilitating the mold release.

The connecting structure of the needle core 30 and the needle cap 40 of the present embodiment is shown in fig. 12, wherein a breakable connecting structure is provided between the needle core 30 and the needle cap 40, and the breakable connecting structure can be broken by rotating the needle cap 40, and the needle cap 40 is separated from the needle core 30. It should be noted that the breakable connection structure belongs to the conventional technology in the art, and the specific structure is not described herein.

In this embodiment, the needle cap 40 includes a main body section 41 connected to the needle core 30 and a flat operating section 42. As a modification of the present embodiment, a pair of oppositely disposed protrusions 43 is provided at a position of the main body section 41 close to the operating section 42.

As shown in FIG. 13, the core 30 of the present embodiment is provided with a puncture needle 31 at one end. The stylet 30 is provided with a pair of oppositely arranged guide blocks 34, the guide blocks 34 penetrate through the guide grooves in the corresponding direction of the cross-shaped guide groove 111 and are matched with the second guide groove 16, and the matching of the guide blocks 34 and the second guide groove 16 forms a second guide mechanism between the stylet and the shell in the embodiment.

In this embodiment, the core 30 is further provided with a pair of oppositely disposed protrusions 33, the protrusions 33 and the guide blocks 34 form a cross-shaped structure 35, and the cross-shaped structure 35 and the cross-shaped guide groove 111 cooperate to form a third guide mechanism between the core 30 and the housing 10 in this embodiment.

In this embodiment, the bump 33 is provided with a first step 32 facing one side of the needle cap.

The inner housing 20 of the present embodiment is constructed as shown in fig. 8 to 11, and the bottom of the inner housing 20 is provided with a lancet hole 21, and the lancet hole 21 receives the puncture needle 31 therethrough. Meanwhile, in the initial state, the needle cap 40 also passes through the blood collecting hole.

In this embodiment, the blood collecting hole 21 has a certain length and width, wherein the maximum distance between the pair of protrusions 43 is greater than the width of the blood collecting hole 21 and less than the length of the blood collecting hole 21. It should be noted that the length and width of the blood sampling hole are relative concepts, and as the edge of the blood sampling hole, the edge may be a linear edge or an arc edge.

In this embodiment, a pair of grooves 29 is disposed on the inner side of the bottom of the inner sleeve 20 corresponding to the blood sampling hole 21, and the grooves 29 are adapted to the protrusions 43 to form a first limiting structure in this embodiment.

In this embodiment, as shown in FIG. 8, a second spring chamber 22 is provided within the inner housing for receiving the retraction spring 60. Preferably, the upper portion of the second spring chamber 22 is formed by struts 23 distributed in four orientations. The advantage of this structure is that the four-direction support 23 can realize the function of the limit retraction spring 60, and has the technical effects of saving materials and reducing cost.

In the present embodiment, as shown in fig. 8 and 9, the inner sleeve 20 is provided with a pair of first elastic arms 24 which are oppositely arranged, and the first elastic arms 24 are provided with second steps 26 which are used for abutting against the first steps 32. Preferably, in the present embodiment, the second step 26 is provided with a support arm 25 at two sides, and the support arm 25 is used for contacting and matching with the inclined surface 13 on the separation part 12.

In this embodiment, the outer side of the first elastic arm of the inner sleeve 20 is further provided with a second elastic arm 27, the free end of the second elastic arm 27 is provided with a fifth step 28, and the fifth step 28 is used for matching with the third step and the fourth step.

As shown in fig. 11, in the present embodiment, an arc-shaped groove 210 for accommodating a rotational movement of the pair of protrusions 43 is provided outside the lancet hole of the inner cap 20.

The disposable safety lancet of the present embodiment has at least six working states, which will be described in detail with reference to the accompanying drawings.

In the present embodiment, the state i is an initial state before use, as shown in fig. 1 and 2. The driving spring is in a first pre-tightening state, the inner sleeve is in a first position relative to the shell, in the first position, a fifth step of the second elastic arm and a third step of the shell are in an abutting state, a first step of the needle core and a second step of the inner sleeve are in a separating state, and a protrusion of the first limiting structure and the groove are in a matching state.

In the state I, the elastic pretightening force of the driving spring is transmitted to the inner sleeve through the needle core, the needle cap and the first limiting structure in sequence and drives the inner sleeve to be kept at the first position. As an initial state, under the condition that the inner sleeve is not compressed in place or the position of the inner sleeve is changed due to vibration in the process of transportation and transfer, the inner sleeve can be restored to the first position under the action of the elastic pretightening force of the driving spring, so that a user can easily judge whether the stylet is triggered or not or prevent the stylet from being triggered mistakenly.

In the second embodiment, as shown in fig. 14 and 15, the operation section is rotated by a predetermined angle, and the pair of protrusions are extended from the longitudinal direction of the blood collection hole by the elastic biasing force of the driving spring. In this state, the protrusion is located outside the inner sleeve, preferably within the arc-shaped groove.

In the state II, after the elastic pretightening force of the driving spring is released, the needle core moves downwards to the first step to be abutted against the second step, and the inner sleeve is still at the first position.

State iii of the present embodiment as shown in fig. 16, in the state ii, the needle cap is freely rotated, and after the needle cap is broken off from the joint and separated from the hub, the state iii of the present embodiment is formed, which is a state in which the preparation for acupuncture is completed.

In the state iv of the present embodiment, as shown in fig. 17, the inner sleeve of the disposable safety lancet in the state iii is contacted with the skin of the patient and is pressed, and the inner sleeve moves upward under the pressure to the state iv, wherein, in the process of moving upward, the second step transmits the driving force to the first step and drives the needle core to compress the driving spring. Meanwhile, in the process of lifting the inner sleeve, the inclined surface of the separating part gradually props open the first elastic arm through the support arm.

The state IV is a limit state that the first step and the second step are separated, and at the moment, the driving spring is compressed to a limit state of a launching energy storage state.

State V in this embodiment is shown in FIG. 18, after state IV, the core is fired to state V, which is the needling state. In this state, the retraction spring is compressed to generate elastic potential energy. The inner sleeve moves to a second position, and in the second position, the fifth step is abutted with the fourth step to prevent the inner sleeve from returning to the initial state.

In this embodiment, state VI is shown in FIG. 19, after use, and after the puncture is completed in state V, the elastic potential energy of the retraction spring drives the stylet to move to the position shown in state VI. In this state, the needle head of the puncture needle is positioned in the inner sleeve, so that the user can be prevented from being accidentally injured.

In conclusion, the above description is only for the preferred embodiment of the present invention and should not be construed as limiting the present invention, and any modification, equivalent replacement, and improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. The utility model provides a disposable safety blood taking needle, includes casing, nook closing member, needle cap, endotheca, drive spring and the spring that contracts of contracting at least, the connection structure who has the easy rupture between nook closing member and the needle cap, it is located between nook closing member and the endotheca to contract the spring, its characterized in that:

the needle cap and the inner sleeve are provided with a first limiting structure, the driving spring is positioned between the needle core and the shell and has a first pre-tightening state, and the elastic pre-tightening force of the driving spring in the first pre-tightening state is transmitted to the inner sleeve through the needle core, the needle cap and the first limiting structure in sequence and drives the inner sleeve to be kept at the first position;

2. The disposable safety lancet of claim 1, wherein the inner housing has a bottom portion provided with a lancet hole having a length and a width, the first stopper structure comprises a pair of protrusions provided on the cap at opposite positions and a groove provided at the bottom portion of the inner housing to fit the protrusions, and a maximum distance between the pair of protrusions is greater than the width of the lancet hole and less than the length of the lancet hole.

3. The disposable safety lancet according to claim 1, wherein the inner case is provided at opposite sides thereof with second elastic arms, free ends of which are provided with fifth steps.

4. A disposable safety lancet according to claim 3, wherein the opposite side of the inner wall of the housing is provided with a third step adapted to abut the fifth step when the inner sleeve is in the first position.

5. The disposable safety lancet of claim 4, wherein the opposite side of the housing is further provided with fourth steps adapted to abut the fifth steps when the inner sleeve is in the second position, the fourth steps being spaced apart from each other by a distance greater than the third steps.

6. A single use safety lancet according to claim 1, wherein the side of the detachment mechanism facing the first resilient arm is beveled.

7. The disposable safety lancet of claim 1, wherein a first spring chamber for receiving a drive spring is provided in said housing and a second spring chamber for receiving a retraction spring is provided in said inner sleeve.

8. The disposable safety lancet according to any one of claims 1 to 7, wherein a first guide means is provided between the inner case and the housing, the first guide means comprising a second elastic arm and a first guide groove provided on an inner wall of the housing to be fitted with the second elastic arm.

9. The disposable safety lancet according to claim 8, wherein a second guide means is provided between the core and the housing, the second guide means comprising a pair of guide blocks oppositely provided on the core and a second guide groove provided on an inner wall of the housing to be fitted with the guide blocks.

10. A disposable safety lancet according to claim 9, further provided with a third guiding means between the core and the housing, the third guiding means comprising: the first step is arranged on the lug; and a cross-shaped guide groove matched with the cross-shaped structure in the separating mechanism.