CN217525970U - Drive mechanism for injection device - Google Patents

Abstract

The utility model aims at providing an injection apparatus's actuating mechanism is applied to injection apparatus and in, this actuating mechanism mainly comprises piston rod, scale screw, set up in the cavity of scale screw and with the cooperation sleeve that the scale screw block is connected, set up in the cavity and its lower extreme and the first sleeve of cooperation sleeve meshing, cover second sleeve etc. of locating in the first sleeve and being used for driving the piston rod to make descending motion. The first sleeve and the second sleeve can form sliding connection along the axial direction; and when the scale screw rod moves up along with the ratchet mechanism, the first sleeve only moves up along the axial direction while the matching sleeve synchronously rotates up. Compared with the prior art, the injection device is simple in structure, the number of the elastic parts can be reduced, and the dose injection precision of the injection device is improved.

Description

Drive mechanism for injection device

Technical Field

The utility model relates to a medical injection pen especially relates to an injection device's actuating mechanism.

Background

An injection device, as a commonly used medical instrument, can replace manual needle insertion, injection and the like to accurately extrude a required dosage.

In the existing injection device, as disclosed in the specification of patent application CN201721593761.8, a transmission mechanism and a medical injection device are provided, in which the rising of a scale screw is realized by the cooperation of a driving key, a transmission ratchet and a transmission ratchet, so as to realize the dose adjustment of the medical injection device.

However, in the prior art, in the driving mechanism of the injection device, the scale screw drives the piston rod to move downwards by means of the corresponding first sleeve and second sleeve under the pressing action of the pressing key so as to squeeze the space inside the syringe, however, the first sleeve and the second sleeve need to be separated by means of the corresponding elastic components so as to realize independent rotation and follow-up rotation of the first sleeve and the second sleeve. However, the elastic member is prone to fail and is not easily replaced when in use, and the elastic member is prone to cause slippage between the first sleeve and the second sleeve under the effect of no external force, so that the accuracy of the injection dosage of the medical injection device is affected.

Therefore, how to provide a simple structure, the drive mechanism of the injection device that can reduce the number of elastic components that set up to promote the dose injection precision of injection device is the utility model discloses the technical problem who needs to solve is urgent.

SUMMERY OF THE UTILITY MODEL

To above-mentioned prior art's shortcoming or not enough, the to-be-solved technical problem of the utility model is to provide an injection device's actuating mechanism, simple structure can reduce elastomeric element's the quantity that sets up, promotes injection device's dose injection precision.

In order to solve the above technical problem, the utility model provides an injection device's actuating mechanism, include: a piston rod; a scale screw;

the matching sleeve is arranged in the cavity of the scale screw and is clamped and connected with the scale screw; a first sleeve disposed within the cavity and having a lower end engaged with the mating sleeve;

the second sleeve is sleeved in the first sleeve and used for driving the piston rod to do descending motion;

wherein the first sleeve and the second sleeve can form a sliding connection along the axial direction; and when the scale screw rod moves up along with the ratchet mechanism, the first sleeve only moves up along the axial direction synchronously while the matching sleeve synchronously moves up and rotates.

Further preferably, the bottom end of the first sleeve is provided with a first ratchet along the circumferential direction; the top end of the matching sleeve is circumferentially provided with a second ratchet for engaging the first ratchet; wherein the engagement direction of the first ratchet and the second ratchet is used for enabling the second ratchet to slide towards the direction of disengaging the first ratchet when the matching sleeve rotates along with the scale screw rod.

Further preferably, the tooth surface of the second ratchet is an arc surface which gradually rises from one end to the other end thereof in the circumferential direction of the fitting sleeve.

Further preferably, a bayonet is arranged on the scale screw; the outer wall of the matching sleeve is provided with a clamping piece which is clamped into the bayonet; the clamping pieces are distributed along the circumferential direction of the matching sleeve; the number of the clamping pieces is the same as that of the matching sleeves.

Further preferably, the number of the engaging pieces is two, and the engaging pieces are symmetrically distributed.

Further preferably, the method further comprises the following steps: an upper housing; a ratchet mechanism; the backstop ratchet wheel is arranged in the upper shell and is meshed with one end of the upper shell; the two opposite ends are respectively used for abutting against the retaining ratchet wheel and an elastic component of the ratchet wheel mechanism;

the anti-return ratchet wheel is connected with the piston rod in a sliding mode, and the piston rod can rotate in a single direction under the action of the elastic assembly so as to extrude the inner space in the needle cylinder of the injection device.

Further preferably, the engagement direction of the backstop ratchet is opposite to the engagement direction of the matching sleeve; one end of the backstop ratchet wheel is circumferentially provided with backstop ratchets; the tooth surface of the retaining ratchet is an arc surface, and the arc surface gradually rises from one end to the other end of the arc surface along the circumferential direction of the retaining ratchet.

Preferably, the upper shell further comprises a baffle plate provided with a through hole for inserting the piston rod; the baffle is arranged at the bottom end of the upper shell and is connected with the side wall of the upper shell; the baffle is provided with built-in ratchets along the circumferential direction for engaging the retaining ratchets.

Further preferably, the backstop ratchet comprises: the bottom end of the circular body is provided with the retaining ratchet, and the positioning insertion piece is arranged on the circular body and used for being clamped and connected with the piston rod; the piston rod is also provided with a positioning chute for inserting the positioning insertion piece in a matching manner; the circular body is further provided with an annular groove for sleeving a sleeve for driving the piston rod.

Further preferably, the elastic member includes: the partition plate is arranged between the ratchet mechanism and the backstop ratchet; the opposite two ends of the first spring are respectively abutted against the ratchet mechanism and the partition plate; the opposite two ends of the second spring are used for respectively abutting against the partition plate and the second spring between the retaining ratchet wheels; wherein the rotation directions of the first spring and the second spring are opposite; the upper shell is provided with a supporting part which partially extends along the radial direction and is used for supporting the clapboard.

The present application further provides an injection device comprising a drive mechanism of the above injection device.

Compared with the prior art, the injection device is simple in structure, the number of the elastic parts can be reduced, and the injection precision of the injection device is improved.

Drawings

Other features, objects and advantages of the present application will become more apparent upon reading of the following detailed description of non-limiting embodiments thereof, made with reference to the accompanying drawings in which:

FIG. 1: the internal structure of the driving mechanism in the first embodiment of the utility model is shown schematically;

FIG. 2 is a schematic diagram: the explosion of the injection device in the first embodiment of the present invention is schematically illustrated;

FIG. 3: the internal structure of the driving mechanism of the injection device in the first embodiment of the utility model is shown schematically;

FIG. 4: the structure of the retaining ratchet wheel in the first embodiment of the utility model is shown schematically;

FIG. 5: the cross-sectional view of the upper shell in the first embodiment of the present invention is schematically shown;

FIG. 6: exploded view of the drive mechanism of the injection device in the first embodiment of the present invention;

FIG. 7: the external structure of the driving mechanism of the injection device in the first embodiment of the present invention is schematically shown;

FIG. 8: the structure schematic diagram of the ratchet mechanism and the driving sleeve in the first embodiment of the utility model;

FIG. 9: the structure schematic diagram of the driving sleeve in the first embodiment of the utility model;

FIG. 10: the structure schematic diagram of the ratchet mechanism in the first embodiment of the utility model;

FIG. 11: the cross-sectional structure of the injection device in the first embodiment of the present invention is schematically illustrated;

FIG. 12: the internal structure of the driving mechanism of the injection device in the second embodiment of the present invention is schematically illustrated;

description of reference numerals: the device comprises an upper shell 1, an upper guide groove 101, a built-in ratchet 102, a supporting part 103, a driving sleeve 2, a driving ratchet 21, a driving slide bar 22, a driving thread 23, a stopping tooth groove 24, a transmission ratchet 3, an upper ratchet 31, a lower ratchet 32, a matching ratchet 4, a matching ratchet 41, a matching slide bar 42, a pressing key 5, a cover body 50, a pressing cover 51, a needle cylinder 6, a lower shell 7, a scale screw 8, a screw guide groove 81, a scale thread 82, a bayonet 83, a partition plate 9, a first spring 10, a second spring 11, a backstop ratchet 12, a backstop ratchet 121, a positioning insertion sheet 122, an annular groove 123, a piston rod 13, a third spring 16, a first sleeve 17, a convex part 172, a first ratchet 171, a matching sleeve 18, a clamping piece 181, a second ratchet 182, a second sleeve 19 and a clamping groove 191.

Detailed Description

The conception, the specific structure and the technical effects of the present invention will be further described with reference to the accompanying drawings, so as to fully understand the objects, the features and the effects of the present invention.

Example one

As shown in fig. 1 to 11, the first embodiment of the present invention provides a driving mechanism of an injection device, which is applied to the injection device, and the driving mechanism mainly comprises a piston rod 13, a scale screw 8, a matching sleeve 18 disposed in a cavity of the scale screw 8 and engaged with the scale screw 8, a first sleeve 17 disposed in the cavity and having a lower end engaged with the matching sleeve 18, and a second sleeve 19 sleeved in the first sleeve 17 and used for driving the piston rod 13 to move downward.

Wherein, the first sleeve 17 and the second sleeve 19 can form a sliding connection along the axial direction; when the scale screw 8 moves up along with the ratchet mechanism, the first sleeve 17 moves up only in the axial direction while the engaging sleeve 18 is rotated up synchronously.

The above results show that: because cooperation sleeve 18 and scale screw 8 are the block connection each other, meshing transmission between cooperation sleeve 18 and the first sleeve 17, and the cooperation of first sleeve 17 and second sleeve 19, simultaneously because scale screw 8 is followed ratchet and is made when rising motion, make cooperation sleeve 18 do synchronous rising rotation simultaneously, first sleeve 17 only makes synchronous rising motion along the axial, consequently whole process need not to adopt elastomeric element etc. can realize independent and synchronous motion between first sleeve 17 and the second sleeve 19, and make first sleeve 17 only make synchronous rising motion along the axial when scale screw 8 rotates, consequently can be when replacing current structure, reduction in production cost.

Further preferably, as shown in fig. 1 and 2, the bottom end of the first sleeve 17 is provided with a first ratchet 171 along the circumferential direction; the tip of the fitting sleeve 18 is provided with second ratchet teeth 182 for engaging the first ratchet teeth 171 in the circumferential direction; wherein the direction of engagement of the first ratchet teeth 171 and the second ratchet teeth 182 is such that when the mating sleeve 18 follows the rotation of the scale screw 8, the second ratchet teeth 182 slide towards a direction of disengaging the first ratchet teeth 171. Since the first ratchet teeth 171 and the second ratchet teeth 182 rotate in the direction in which the second ratchet teeth 182 thereof are disengaged from the first ratchet teeth 171 when the engaging sleeve 18 follows the scale screw 8, the first ratchet teeth 171 and the second ratchet teeth 182 are moved in the direction in which they are disengaged from each other when the engaging sleeve 18 follows the scale screw 8, and since the engaging sleeve 18 is also moved axially while following the scale screw 8, the first ratchet teeth 171 and the second ratchet teeth 182 are disengaged from each other and then re-engaged by the sliding action of the engaging sleeve 18, so that the engaging sleeve 18 is in the idle rotation state and pushes the first sleeve 17 to move synchronously upward along the axial direction thereof by a predetermined displacement when the engaging sleeve 18 is idle-rotated by one stroke, i.e., one ratchet tooth.

In addition, it is worth mentioning that the tooth surface of the second ratchet teeth 182 in this embodiment is an arc surface, and the arc surface gradually rises from one end to the other end along the circumferential direction of the mating sleeve. Similarly, the tooth surface of the first ratchet 181 is also an arc surface which gradually rises from one end to the other end thereof in the circumferential direction of the mating sleeve. Here, it is worth mentioning that, when the tooth surfaces of the first ratchet tooth 181 and the second ratchet tooth 182 reach the highest point, a cross section is generated and then connected with the lowest point of the adjacent ratchet tooth.

As shown in fig. 1 and 2, in order to facilitate assembly and disassembly in practical application, the matching sleeve and the scale screw rod can move synchronously, and a bayonet is arranged on the scale screw rod; the outer wall of the matching sleeve is provided with a clamping piece 181 which is clamped into the bayonet. Wherein, the engaging pieces 181 are distributed along the circumference of the engaging sleeve; the number of the engaging pieces 181 is the same as the number of the engaging sleeves.

In addition, as shown in fig. 1, the driving mechanism of the injection device in this embodiment mainly includes: the device comprises an upper shell 1, a ratchet mechanism, a backstop ratchet 12 arranged in the upper shell 1 and used for meshing one end of the upper shell 1, elastic components and the like, wherein the two opposite ends of the elastic components are respectively used for propping against the backstop ratchet 12 and the ratchet mechanism. The anti-backing ratchet 12 is slidably connected to a piston rod 13 of the injection device, and under the action of the elastic component, the piston rod 13 rotates in one direction to extrude the inner space of the syringe 6 of the injection device.

The above results show that: since the anti-backing ratchet 12 is slidably connected to the piston rod 13, and the anti-backing ratchet 12 is always required to be engaged with one end of the upper housing 1 under the squeezing action of the elastic component, and when the piston rod 13 rotates along the engaging direction of the anti-backing ratchet 12, because the anti-backing ratchet 12 is usually engaged with the bottom end of the upper housing 1, and therefore cannot rotate, when the piston rod 13 rotates along the engaging direction departing from the anti-backing ratchet 12, the anti-backing ratchet 12 can be disengaged from the bottom end of the upper housing 1, and simultaneously moves upwards for a certain distance, and after rotating a tooth stroke, the anti-backing ratchet 12 is engaged with the bottom end of the upper housing 1 under the elastic action, so that the piston rod 13 can only rotate in one direction through the cooperation of the anti-backing ratchet 12, the upper housing 1 and the piston rod 13 to squeeze the inner space in the syringe 6, thereby preventing the piston rod from backing-back phenomenon, and realizing the precise control of the driving mechanism of the injection device.

Specifically, in order to ensure that the piston rod 13 can only rotate in one direction to squeeze the inner space of the cylinder 6, a structure is adopted in which the engagement direction of the backstop ratchet 12 is opposite to that of the mating sleeve; the bottom end of the backstop ratchet wheel 12 is provided with backstop ratchets 121 along the circumferential direction.

In addition, it should be mentioned that the tooth surface of the stopping ratchet 121 in this embodiment is an arc surface, and the arc surface gradually rises from one end to the other end of the arc surface along the circumferential direction of the stopping ratchet.

Further preferably, the upper housing 1 further includes a baffle (not shown in the figures) having a through hole for inserting the piston rod 13; wherein, the baffle set up in the bottom of last casing 1, and link to each other with the lateral wall of last casing 1. Further, the baffle is provided with a built-in ratchet 102 in the circumferential direction for engaging the retaining ratchet.

It should be noted that the stopping ratchet 12 of the present embodiment is mainly composed of a circular body (not shown) provided with the stopping ratchet, a positioning insertion piece 122 provided on the circular body and used for engaging and connecting the piston rod, and the like.

In addition, the anti-backing ratchet 12 further includes an annular groove 123 disposed on the circular body for sleeving a sleeve for driving the piston rod 13.

Further preferably, as shown in fig. 3, the elastic member includes: a partition plate 9 arranged between the ratchet mechanism and the backstopping ratchet 12; the opposite two ends are respectively propped against the ratchet mechanism and a first spring 10 of the clapboard 9; the two opposite ends are used for respectively abutting against a second spring 11 between the partition plate 9 and the backstop ratchet wheel 12.

By arranging the partition plate 9 between the ratchet mechanism and the backstop ratchet wheel 12 and arranging the first spring 10 and the second spring 11 on two sides of the partition plate 9 respectively, the ratchet mechanism and the backstop ratchet wheel 12 are mutually independent, and particularly the backstop ratchet wheel 12 cannot be pressed all the time due to the up-and-down movement of the ratchet mechanism, so that the backstop ratchet wheel 12 can normally run along with the piston rod 13 when the scale screw 8 rotates.

Further preferably, in order to prevent the partition board 9 from rotating to the maximum extent, so as to avoid the partition board from driving the first spring 10 or the second spring 11 to rotate, the rotation directions of the first spring 10 and the second spring 11 are opposite, so as to counteract the mutual torque.

Further preferably, the upper casing 1 has a bearing portion 103 partially protruding in the radial direction to form a bearing for bearing the partition 9. Therefore, the partition plate 9 can be clamped on the bearing part 103 under the abutting of the first spring 10, and is fixed on the part where the bearing part 103 is located, so as to avoid the floating of the partition plate between the ratchet mechanism and the backstop ratchet 12 caused by the up-and-down floating of the partition plate, and further avoid the adjustment error of the dosage.

Obviously, it should be mentioned that the elastic component in this embodiment may also be implemented by only one or a plurality of springs stacked up and down without providing a partition, or by providing the supporting portion 103 in a protruding manner, so that the opposite sides thereof respectively abut against the first spring 10 and the second spring 11, and details and limitations are not repeated herein.

In addition, as shown in fig. 2 to 11, the drive mechanism of the injection device further includes a drive sleeve 2 and the like rotatably connected to the upper case 1 in the circumferential direction.

Wherein, the top end of the ratchet mechanism is used for forming meshing transmission with the driving sleeve 2, and the circumferential direction is used for rotationally connecting the driving sleeve 2. And, the driving sleeve 2 is used for driving the ratchet mechanism to make synchronous motion when the upper shell 1 rotates along the set direction, so that the scale screw 8 makes synchronous ascending motion.

The above results show that: because the upper shell 1 is rotationally connected with the driving sleeve 2, the top end of the ratchet mechanism is meshed with the driving sleeve 2 for transmission, and the circumference of the ratchet mechanism is rotationally connected with the driving sleeve 2, the ratchet mechanism can synchronously rotate and drive the scale screw 8 to synchronously move upwards when the upper shell 1 rotates through the matching of the driving sleeve 2 and the ratchet mechanism, and the scale screw 8 can also ascend without being driven by pressing a key, thereby realizing the dose adjustment and control of the injection device. In addition, the driving mechanism of the injection device provided by the application does not need to use keys to control and adjust the dose, and can be realized only by rotating the upper shell 1, so that the structure of the injection device is simplified, and the use and the carrying of a user are facilitated.

Specifically, as shown in fig. 8, the bottom of the driving sleeve 2 is provided with a driving ratchet 21; the drive ratchet 21 is arranged along the circumferential layout of the drive sleeve 2; the number of the drive ratchets 21 is eight or less.

By this arrangement, the stroke of the drive sleeve 2 for one rotation is made larger to reduce the number of rotations of the user, and to achieve adjustment and control of a large dose.

In addition, the ratchet mechanism in the present embodiment is preferably mainly constituted by the transmission ratchet 3, the engaging ratchet 4 which forms meshing transmission with the transmission ratchet 3 and is used for rotating the connection scale screw 8, and the like. Moreover, the top end of the transmission ratchet wheel 3 is provided with an upper ratchet 31 for meshing the driving ratchet 21 along the circumferential direction, and the bottom end is provided with a lower ratchet 32 for meshing the matching ratchet 4 along the circumferential direction; wherein, the top end of the matching ratchet wheel 4 is provided with a matching ratchet 41 for meshing the lower ratchet 32 along the circumferential direction; upper ratchet 31 and lower ratchet 32; wherein the number of the upper ratchet teeth 31 is smaller than the number of the lower ratchet teeth 32.

Because the number of the upper ratchets 31 and the lower ratchets 32 in the transmission ratchet wheel 3 is inconsistent, the clicking sound can be generated while the adjustment of a larger stroke is realized, and the operation is convenient.

Further preferably, the number of teeth of the fitting ratchet 41 and the lower ratchet 32 is the same; the number ratio between the upper ratchet 31 and the lower ratchet 32 is 2-12. To realize the control of a large stroke by setting the ratio of the number of the upper ratchet 31 to the lower ratchet 32.

Further preferably, the number of the driving ratchet 21 and the upper ratchet 31 is the same or different in order to meet the assembly and design in practical use. Wherein the drive ratchet 21 is larger in size than the lower ratchet 32.

Further preferably, in the present embodiment, the drive ratchet teeth 21 are arranged equidistantly in the circumferential direction; the number of the drive ratchet 21 is four; the number of the upper ratchet teeth 31 is two.

Further preferably, as shown in fig. 5 and 9, the outer wall of the upper casing 1 is provided with a plurality of upper guide grooves 101 arranged along the axial direction thereof, wherein each upper guide groove 101 is arranged in a circumferential surrounding arrangement along the outer wall of the upper casing 1; the outer wall of the drive sleeve 2 is provided with a number of drive slides 22 arranged along its axial layout for sliding engagement with the upper guide grooves 101. By the cooperation of the upper guide groove 101 and the driving slide 22, the synchronous rotation between the upper housing 1 and the driving sleeve 2 can be realized, and the driving sleeve 2 does not slide axially.

Further preferably, as shown in fig. 3 and 8, the outer wall of the scale screw 8 is provided with a plurality of screw guide grooves 81 along the axial layout thereof, wherein each screw guide groove 81 is circumferentially arranged along the outer wall of the scale screw 8; the inner wall of the engaging ratchet 4 is provided with a plurality of engaging sliding strips 42 arranged along the axial direction thereof for sliding engagement with the screw guide grooves 81. Through the cooperation of the screw guide groove 81 and the matching slide bar 42, the scale screw 8 synchronously rotates along with the matching ratchet 4, and simultaneously, the scale screw 8 can synchronously move upwards along the axial direction of the scale screw 8 by virtue of the threaded connection between the scale screw 8 and the top end of the driving sleeve 2.

Further, it is preferable that the drive mechanism of the injection device further includes: a pressing key 5; a third spring 16 with one end sleeved on the scale screw 8 and the other end used for supporting the pressing button. The third spring 16 keeps a set distance between the pressing key and the driving sleeve 2, so that the phenomenon that the scale screw 8 descends when the pressing key 5 is triggered by self gravity or by external force by mistake and the piston rod 13 is pushed to move along with the descending movement, and the piston rod 13 extrudes the inner space in the needle cylinder 6 to cause larger error is avoided.

In the present embodiment, the pressing button is mainly composed of a cover 50 provided in the through hole of the driving sleeve 2 and engaged with the upper end of the scale screw, a pressing cap 51 provided on the cover 50, and the like, for the convenience of the user's operation and use. Wherein, the third spring is sleeved on the scale screw and abuts against the pressing cover 51.

The center of the pressing cover 51 is provided with a fixed shaft 52, the fixed shaft 52 is inserted into the cavity of the scale screw 8 from the hollow part of the cover body 50, and the central axis of the fixed shaft 52 coincides with the central axis of the scale screw 8. Therefore, after the user presses the pressing cover 51, the cover body 50 drives the scale screw 8 to move downwards under the action of the pressing cover 51, and rotates around the fixed shaft 52 as a central axis to drive the first sleeve 17 to rotate. Meanwhile, since the fixed shaft 52 is inserted into the cavity of the scale screw 8 from the hollow part of the cover body 50, the assembly and positioning between the cover 51 and the cover body 50 and between the fixed shaft and the scale screw 8 can be pressed conveniently in actual use.

Further, as shown in fig. 9, the inner wall of the driving sleeve 22 in the present embodiment is further provided with a driving screw 23 for screw-coupling with the scale screw 8. In addition, a stopping tooth groove 24 for matching with a pressing ratchet (not shown) arranged on the insertion cover 50 is further formed at the top end of the driving sleeve 22 along the circumferential direction, so that when the pressing key 5 is pressed to a position touching the driving sleeve, the rotation can be stopped, and the phenomenon that the piston rod 13 is further driven to rotate by the inertial rotation of the pressing key 5, and the injected dose is deviated from the regulated and scaled dose is avoided.

In addition, as shown in fig. 9, the inner wall of the driving sleeve 22 in the present embodiment is further provided with a driving screw 23 for screwing the scale screw 8. Furthermore, the top end of the driving sleeve 22 is further provided with a pressing ratchet (not labeled in the figure) along the circumferential direction for being inserted into the cover 50 in a matching manner, so that when the pressing key 5 is pressed to a position touching the driving sleeve, the rotation can be stopped, and the inertial rotation of the pressing key 5 is avoided to further drive the piston rod 13 to rotate, so that the injected dose and the adjusted and scaled dose have a deviation phenomenon.

It should be noted that, as a preferable mode, the upper end of the first sleeve 17 is provided with a protrusion 172, and correspondingly, the upper end of the second sleeve 19 is provided with a locking groove 191 for engaging with the protrusion 172, wherein when the scale screw 8 is spirally lifted, the protrusion 172 slides upward in the locking groove 191.

In the actual design process, when the scale screw 8 is screwed down, the first sleeve 17 slides downwards in the slot 191 of the second sleeve 19 under the meshing transmission action of the matching sleeves, and drives the second sleeve 19 to rotate. Thereby the bellying 172 of accessible first sleeve 17 is in the slip of the draw-in groove 191 of second sleeve for second sleeve 19 can be steady when scale screw 8 spiral rises, slides along its axial, and can be when it follows scale screw 8 and does the spiral decline, through mutually supporting between bellying 172 and the draw-in groove 191, produces the moment of torsion to second sleeve 19, thereby drives second sleeve 19 synchronous revolution, guarantees driven stability.

The protruding portion 172 is formed by a plurality of protruding members which are disposed at the top end of the cavity of the first sleeve 17 and extend upward along the axial direction thereof, and in this embodiment, the number of the protruding members is preferably two, and the protruding members are symmetrically disposed at the top end of the first sleeve 17, and the protruding members are formed by a horizontal section (not shown in the figure) and a vertical section (not shown in the figure), and the horizontal section is connected to the top end of the cavity of the first sleeve 17. Correspondingly, the top end of the cavity of the second sleeve 19 has an opening extending partially upward and passing through the top end of the cavity of the first sleeve 17, and forms a clamping portion (not shown) having a clamping groove 191.

In order to prevent the second sleeve 19 and the first sleeve 17 from being separated during the relative sliding, in the actual design and application process, it is preferable that the maximum displacement of the relative sliding between the protrusion 172 and the slot 191, i.e. the relative displacement between the second sleeve 19 and the first sleeve 17, be less than the length of the external thread on the scale screw 8, i.e. the distance between the start section and the end section of the external thread in the axial direction of the scale screw 8 (corresponding to the maximum distance of the scale screw 8 rising), and obviously, the relative displacement may also be equal to the length of the external thread on the scale screw 8, which is not described in the embodiment too much and briefly.

Example two

This embodiment also provides a drive mechanism for an injection device, and is substantially the same as the above-described embodiments except that, as shown in fig. 12, the ratchet mechanism in this embodiment is mainly constituted by the engaging ratchet 4. Wherein, the top end of the matching ratchet wheel 4 is provided with a matching ratchet 41 used for meshing the driving ratchet 21 along the circumferential direction; the number of the fitting ratchet teeth 41 and the drive ratchet teeth 21 is the same.

Because the upper and lower gears of the matching ratchet wheel 4 and the driving ratchet 21 are consistent in number, and because the gear interval of the driving sleeve 2 is larger, the adjustment of a larger stroke can be realized, and the dosage mark line on the scale screw 8 is easy to cause the reading error of the dosage because the dosage mark line stays between two marked scales when the scale screw 8 is retracted.

EXAMPLE III

The present application further provides an injection device comprising a drive mechanism of the above injection device.

In addition, it should be noted that, each of the further preferable solutions related to the embodiment is a solution added or improved according to actual situations to solve corresponding technical problems, so that the parts and structures related to the embodiment are not necessary for realizing the technical problem of how to precisely control the transmission stroke to meet the design requirement of high-precision transmission, and can be set according to actual situations, and the embodiment is not specifically limited and described herein.

The above embodiments are only used to illustrate the technical solution of the present invention, but not to limit the same, and the present invention is described in detail with reference to the preferred embodiments. It should be understood by those skilled in the art that various modifications and equivalent substitutions may be made to the embodiments of the present invention without departing from the spirit and scope of the embodiments of the present invention, and the scope of the appended claims should be construed accordingly.

Claims (10)

1. A drive mechanism for an injection device comprising: a piston rod; a scale screw; it is characterized by also comprising:

the matching sleeve is arranged in the cavity of the scale screw and is connected with the scale screw in a clamping way;

a first sleeve disposed within the cavity and having a lower end engaged with the mating sleeve;

the second sleeve is sleeved in the first sleeve and used for driving the piston rod to do descending motion;

wherein the first sleeve and the second sleeve can form a sliding connection along the axial direction; and when the scale screw rod moves up along with the ratchet mechanism, the first sleeve only moves up along the axial direction while the matching sleeve synchronously rotates up.

2. The drive mechanism of an injection device according to claim 1, wherein the bottom end of the first sleeve is circumferentially provided with first ratchet teeth; the top end of the matching sleeve is circumferentially provided with a second ratchet for meshing with the first ratchet; wherein the engagement direction of the first ratchet and the second ratchet is used for enabling the second ratchet to slide towards the direction of disengaging the first ratchet when the matching sleeve rotates along with the scale screw rod.

3. The drive mechanism of an injection device according to claim 2, wherein the tooth face of the second ratchet is a curved face which rises stepwise in the circumferential direction of the fitting sleeve from one end to the other end thereof.

4. The driving mechanism of the injection device according to claim 1, wherein the calibration screw is provided with a bayonet; the outer wall of the matching sleeve is provided with a clamping piece which is clamped into the bayonet; the clamping pieces are distributed along the circumferential direction of the matching sleeve; the number of the clamping pieces is the same as that of the matching sleeves.

5. The drive mechanism of an injection device as set forth in claim 4, wherein said engaging members are two in number and are symmetrically disposed.

6. The drive mechanism of an injection device according to any of claims 1 to 5, further comprising: an upper housing; a ratchet mechanism; the backstop ratchet wheel is arranged in the upper shell and is meshed with one end of the upper shell; the two opposite ends are respectively used for abutting against the retaining ratchet wheel and an elastic component of the ratchet wheel mechanism;

the anti-return ratchet wheel is connected with the piston rod in a sliding mode, and the piston rod can rotate in a single direction under the action of the elastic assembly so as to extrude the inner space in the needle cylinder of the injection device.

7. A drive mechanism for an injection device according to claim 6, wherein the direction of engagement of the backstop ratchet is opposite to the direction of engagement of the co-operating sleeve; one end of the backstop ratchet wheel is circumferentially provided with a backstop ratchet; the tooth surface of the retaining ratchet is an arc surface, and the arc surface gradually rises from one end to the other end along the circumferential direction of the retaining ratchet.

8. The driving mechanism of an injection device according to claim 6, wherein the upper housing further comprises a baffle plate having a through hole for inserting the piston rod; the baffle is arranged at the bottom end of the upper shell and is connected with the side wall of the upper shell; the baffle is provided with built-in ratchets along the circumferential direction for engaging the retaining ratchets.

9. The drive mechanism of an injection device as set forth in claim 6, wherein the backstop ratchet comprises: the bottom end of the circular body is provided with the retaining ratchet, and the positioning insertion piece is arranged on the circular body and used for being clamped and connected with the piston rod; the piston rod is also provided with a positioning chute for inserting the positioning insertion piece in a matching manner; the circular body is further provided with an annular groove for sleeving a sleeve for driving the piston rod.

10. A drive mechanism for an injection device according to claim 6, wherein the resilient assembly comprises: the partition plate is arranged between the ratchet mechanism and the backstop ratchet; the opposite two ends of the first spring are respectively abutted against the ratchet mechanism and the partition plate; the opposite two ends of the second spring are used for respectively abutting against the partition plate and the second spring between the retaining ratchet wheels; wherein the rotation directions of the first spring and the second spring are opposite; the upper shell is provided with a supporting part which partially extends along the radial direction and is used for supporting the clapboard.

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