CN221314279U - Self-fastening mechanism for rotating shaft of reciprocating rotating mechanism and related electric scissors - Google Patents

Abstract

The present utility model relates to a self-fastening mechanism for a rotary shaft of a reciprocating rotary mechanism, the reciprocating rotary mechanism comprising a fixed bracket and a rotary member, the rotary shaft being arranged in a through hole penetrating the rotary member and the fixed bracket such that the rotary member is configured to move rotationally relative to the fixed bracket around the rotary shaft, wherein the rotary shaft comprises a nut-like configuration integrally configured with the rotary shaft at one end thereof and is screwed by means of a nut at the other end such that the rotary member is assembled pressed against the fixed bracket, wherein the rotary member is configured to rotate reciprocally in opposite directions; the self-fastening mechanism includes a ratchet provided on a circumferential outer side of the nut and a pawl fixedly provided on the fixing bracket and engaging the ratchet. The utility model also relates to an electric shears comprising a self-fastening mechanism as described above. According to the self-fastening mechanism for a rotary shaft of the present utility model, it is possible to maintain a proper degree of press-fitting assembly of the reciprocating rotary mechanism.

Description

Self-fastening mechanism for rotating shaft of reciprocating rotating mechanism and related electric scissors

Technical Field

The present application relates generally to a self-fastening mechanism for a rotating shaft of a reciprocating rotary mechanism, and more particularly to an electric scissors.

Background

As is known in the art, for some reciprocating rotary mechanisms, a rotating shaft is typically required to extend through the rotating components of the reciprocating rotary mechanism to press the rotating components into assembly to a stationary support.

Such a rotation shaft is usually ensured at both ends by means of a limit structure not to disengage the rotation element and to ensure a press-fit between the rotation element and the stationary support without causing malfunction or danger of the rotation mechanism. The most common way is to screw the rotation shaft at one end thereof by means of a screw structure and to ensure the press-assembly of the rotation member to the fixing bracket at the other end by means of a nut-like structure integrally constructed with the rotation shaft.

There has been a construction on the market that ensures stability of such press-against assembly of the rotary member by means of a click-on mechanism, for example, as shown in fig. 1, in which a tooth 14 is provided on the circumferential outside of a nut 12 for screw-fixing one end thereof in the rotary shaft 10 and a click-on 18 fixedly connected to a fixing bracket 16 of the rotary mechanism 1 engages the tooth of the nut, thereby ensuring that the nut 12 does not undergo any additional rotation upon rotational movement of the rotary member 102 by means of the click-on 18, thereby enhancing stability between the nut 12 and the rotary shaft 10. However, such an arrangement generally has a problem in that since the contact of the rotary member 102 with the rotary shaft 10 causes the rotary shaft to be relatively displaced between the rotary shaft 10 and the nut 12 generally with the rotation of the rotary member 102 or due to the mechanical vibration of the rotary member 20, the screw structure is generally loosened with the wear of the rotary shaft 10 caused by such relative displacement, resulting in a slight displacement of the rotary shaft 10 in the axial direction, which is particularly serious in the case where the rotary member 10 can be reciprocally rotated in different directions. Further, the fixed bracket 16 and the rotary member 102 are also worn away from each other after being pressed against each other for continuous operation, resulting in a slight change in the total thickness of the fixed bracket 16 and the rotary member 102. At this time, the rotation shaft may be slightly displaced with respect to the fixed bracket 16 and thus further abrade the screw structure due to the loosening of the screw mechanism and/or the mutual abrasion between the fixed bracket 16 and the rotating member 102, so that the rotation of the rotating member 102 may be subject to the possibility of shaking. Therefore, the user typically needs to manually tighten the threaded structure to ensure proper operation of the rotating component 102.

Disclosure of utility model

The present application relates to a self-fastening mechanism for a rotary shaft of a reciprocating rotary mechanism, the reciprocating rotary mechanism comprising a fixed bracket and a rotary member, the rotary shaft being arranged in a through hole penetrating the rotary member and the fixed bracket such that the rotary member is configured to move rotationally relative to the fixed bracket around the rotary shaft, wherein the rotary shaft comprises a nut-like configuration integrally configured with the rotary shaft at one end thereof and is screwed by means of a nut at the other end such that the rotary member is assembled pressed against the fixed bracket, wherein the rotary member is configured to rotate reciprocally in opposite directions; the self-fastening mechanism includes a ratchet provided on a circumferential outer side of the nut and a pawl fixedly provided on the fixing bracket and engaging the ratchet, wherein the nut is configured to contact a surface of the fixing bracket in a normal operation state of the reciprocating rotary mechanism such that a predetermined contact friction force is formed between the fixing bracket and the nut.

Further, the nut is configured to be rotationally movable only in a single direction with respect to the pawl when the pawl engages the ratchet teeth, and the single direction corresponds to a tightening direction of the nut.

Further, the self-tightening mechanism is configured such that when the friction remaining between the rotation shaft and the threaded fixation between the nut is greater than the friction between the nut and the surface of the fixed bracket, then when the rotation member rotates in a single direction, the rotation shaft is driven to rotate in a single direction and the rotation shaft will further drive the nut to rotate together in a single direction.

Further, the self-fastening mechanism is further provided with an elastic means which is compressively disposed between the nut-like structure of the rotation shaft and the rotation member such that one end of the elastic means abuts against the nut-like structure and the other end abuts against the rotation member, and the rotation member is configured with a receiving portion for receiving the elastic means such that the other end abuts against a bottom of the receiving portion in the rotation member, the receiving portion being disposed concentrically with the through hole and having a height smaller than that of the elastic means in a free state.

Further, the number of ratchet teeth or circumferential arc is determined such that upon rotational displacement of the nut relative to the stationary support, rotational displacement is ensured across the arc of at least one ratchet tooth such that the pawl engages at least the next ratchet tooth.

Further, the ratchet occupies a circumferential arc that is any integer multiple of the arc of maximum rotational displacement that the rotating shaft is driven to travel upon a single rotation of the rotating member in a single direction.

Further, the ratchet teeth are identical to each other and are equally spaced apart in the circumferential direction of the nut.

Further, the pawl includes pawl adjustment means to adjust the pressure of the pawl against the ratchet teeth on the nut.

Further, the pawl adjustment means is a coil spring adjustment means such that the pressure of the pawl against the ratchet teeth on the nut is adjusted by adjusting the pressure of the coil spring biasing the pawl toward the nut.

The utility model also relates to a pair of electric shears comprising at least a shears head and a support for supporting the shears head of the electric shears, the shears head comprising a fixed shears blade fixedly assembled to the support; a movable scissor blade driven to reciprocate by the driving portion; a rotation shaft provided in a through hole penetrating at least the movable blade and the bracket such that the movable blade is configured to be rotationally moved about the rotation shaft with respect to the bracket and the fixed blade, wherein the rotation shaft includes a nut-like configuration integrally configured with the rotation shaft at one end thereof and is screwed at the other end by means of a nut such that the movable blade is press-assembled with the fixed blade, wherein the scissor head further includes a self-fastening mechanism including a ratchet provided on a circumferential outer side of the nut and a pawl fixedly provided on the fixed bracket and engaging the ratchet, wherein the nut is configured to contact a surface of the bracket such that a predetermined contact friction force is formed between the bracket and the nut in a normal operation state of the scissor head.

The self-tightening mechanism according to the present application is capable of ensuring that the screw mechanism always maintains a relatively stable degree of tightening, i.e., a proper degree of press-fitting assembly of the reciprocating rotary mechanism, so that the rotary shaft of the rotary mechanism always maintains a relatively preferable state suitable for the rotary member to fulfill its function. Furthermore, with the self-fastening mechanism of the present application, easy disassembly of the reciprocating rotary mechanism is ensured without substantial additional tools.

Drawings

Other advantages and aspects of the application will become apparent upon consideration of the following detailed description, taken in conjunction with the accompanying drawings, in which:

FIG. 1 is a schematic view of a jaw mechanism for ensuring that a nut is in proper position according to the prior art;

fig. 2 is a general schematic view of the self-fastening mechanism for the rotary shaft of the reciprocating rotary mechanism according to the present utility model in an assembled state; and

Fig. 3 is a cross-sectional view of an electric shears employing the self-fastening mechanism for a rotary shaft according to the present utility model.

Detailed Description

In the context of the present application, the same reference numerals designate the same or similar elements or portions.

Further, in the context of the utility model, the axial direction refers to a body direction along the rotational axis of the rotation mechanism, which is parallel to or coincides with the rotational axis of the rotational axis. The circumferential direction means a direction in which the outer circumference of the rotary shaft extends, which is perpendicular to the axial direction. The radial direction is parallel or coincident with the radial direction of the axis of rotation. While the above-described orientations are defined in relation to one another, the above-described orientations are merely exemplary and not limiting, and one of ordinary skill in the art will be able to reasonably define the orientations in accordance with their actual needs without departing from the scope of the present utility model.

Fig. 1 shows a schematic view of a jaw mechanism 18 according to the prior art, which ensures that the nut 10 is in a proper position, which has been described in the background section of the application, and which is not described in any greater detail here to prevent redundancy.

Fig. 2 shows a general schematic of a self-fastening mechanism 204 of a rotary shaft 200 for a reciprocating rotary mechanism 2 according to the utility model in an assembled state. In the embodiment of the present utility model, the rotation mechanism 2 includes a fixed bracket 206 and a rotation member 208, and the rotation shaft 200 is disposed in a through hole penetrating the rotation member 208 and the fixed bracket 206 such that the rotation member 208 can reciprocally rotate with respect to the fixed bracket 206 about the rotation shaft 200. The rotary shaft 200 includes a head (not shown) at one end thereof, which may be configured as a nut-like structure (not shown) integrally constructed with the rotary shaft 200 to abut against and hold the rotary member 208, and is screwed at the other end by means of a nut 210 such that the rotary shaft 200 is defined in a through hole penetrating the rotary member 208 and the fixed bracket 206 to achieve press-fitting assembly of the rotary member 208 and the fixed bracket 206. The rotary member 208 can be driven to rotate by a power section (not shown), as will be appreciated by those skilled in the art. The rotary member 208 is capable of reciprocating rotation in opposite directions, as will be appreciated by those skilled in the art.

The self-fastening mechanism 204 includes a ratchet 212 provided on a circumferential outer side of the nut 210 and a pawl 214 fixedly provided on the fixing bracket 206, wherein the nut 210 is configured to contact a surface of the fixing bracket 206 when the reciprocating rotary mechanism 2 is in a normal operation state such that a predetermined contact friction force is formed between the fixing bracket 206 and the nut 210. In the embodiment of the present application, the side of the nut 210 that contacts the fixing bracket 206 is referred to as a contact side and the surface of the fixing bracket 206 that contacts the nut 210 is referred to as a contact surface.

The pawl 214 is fixedly disposed on the fixed bracket 206 without any displacement and the pawl 214 is configured to engage the ratchet teeth 212 of the nut 210 such that in this state the nut 210 is only rotatable in a single direction relative to the pawl 214. In an embodiment of the present application, the single direction corresponds to a tightening direction of the nut 210.

The principle of self-tightening of the rotation shaft 200 by the self-tightening mechanism 204 will be described below. With the just assembled reciprocating rotary mechanism 2, when the rotary shaft 200 is appropriately fixed by the nut 210 to press the rotary member 208 against the fixed bracket 206 for assembly, the screw fixation between the rotary shaft 200 and the nut 210 may be regarded as not yet having wear and the rotary member 208 and the fixed bracket 206 may also be regarded as not having any wear, at which time the screw fixation between the rotary shaft 200 and the nut 210 ensures that no relative displacement occurs therebetween to ensure the press-against assembly of the reciprocating rotary mechanism and that a sufficient predetermined friction force is provided between the contact side of the nut 210 and the contact surface of the fixed bracket 206 to prevent any rotational displacement of the rotary shaft 200 with the rotation of the rotary member 208 due to circumferential contact on the shaft with the rotary member 208. In other words, in this state, sufficient stress is provided between the rotation shaft 200 and the nut 210 and between the contact side and the contact surface to prevent any movement of the nut 210, thereby ensuring the press-fit assembly of the rotation member 208 and the fixing bracket 206 with each other.

Since the rotation shaft 200 is slightly displaced in the axial direction with respect to the nut 210 (a wear gap is generated due to the wear of the threads of the screw fixation and/or a thickness reduction caused by the mechanical wear between the rotation member 208 and the fixing bracket 206) and thus is in an abnormal state when the screw fixation between the rotation shaft 200 and the nut 210 is mechanically worn or due to the mechanical wear between the rotation member 208 and the fixing bracket 206, etc., the pressure between the contact side of the nut 210 and the contact surface of the fixing bracket 206 becomes small, and thus the friction between the contact side and the contact surface is reduced and thus the rotation shaft 200 may be driven to slightly rotate with respect to the fixing bracket 206 due to the circumferential contact thereof with the rotation member 208.

At this time, when the friction force remaining between the screw fixation between the rotation shaft 200 and the nut 210 (hereinafter, simply referred to as screw friction force) is greater than the friction force between the contact side and the contact surface, then when the rotation member 208 rotates in the single direction, the rotation shaft 200 is driven to rotate in the single direction due to the circumferential contact with the rotation member 208 and the rotation shaft 200 will further drive the nut 210 to rotate in the single direction. When the rotating member 208 rotates in the other direction opposite to the one direction, the rotating shaft 200 is driven to rotate in the other direction due to the circumferential contact with the rotating member 208, but the nut 210 cannot rotate in the other direction together with the rotating shaft 200 due to the engagement of the pawl 214 with the ratchet 212, and at this time, the nut 210 is not subjected to any rotational displacement. In this case, the rotation shaft 200 is driven to rotate in the other direction with respect to the nut 210, and at this time, since the one direction corresponds to the tightening direction of the nut 210, since the nut 210 is restrained from rotating in the other direction by the pawl 214, the rotation of the rotation shaft 200 in the other direction will produce a tightening effect with each other between the rotation shaft 200 and the nut 210 until the remaining friction between the screw fixation between the rotation shaft 200 and the nut 210 is smaller than the friction between the contact side and the contact surface, thereby achieving a self-tightening effect between the nut 210 and the rotation shaft 200, as understood by those skilled in the art. Accordingly, even if thread fixing looseness occurs or wear between the rotating member 208 and the fixed bracket 206 occurs, automatic fastening between the nut 210 and the rotating shaft 200 can be achieved by the reciprocating rotation of the rotating member 208, thereby maintaining the friction force between the contact side of the nut 210 and the contact surface of the fixed bracket 206 at a stable level (i.e., not being too low at all, resulting in serious shaking or risk of stoppage between the rotating member 208 and the fixed bracket 206), thereby ensuring safe and continuous operation of the reciprocating rotary mechanism 2. Further, in some cases, the above condition that causes the nut 210 to rotate together with the rotation shaft 200 in a single direction can also be expressed more precisely as when the thread friction force between the rotation shaft 200 and the thread fixing between the nut 210 is larger than the sum of the friction force between the contact side and the contact surface and the friction force provided between the pawl 214 and the ratchet 212 (it should be understood by those skilled in the art that the friction force between the pawl 214 and the ratchet 212 is generally fixed and small because if the friction force is too large, this would cause a malfunction between the pawl 214 and the ratchet 212 (for example, cause no tooth jump to occur), so the friction force is generally set to be able to achieve the function of the pawl 214 and the ratchet 212 without being too large, and in fact, the friction force is generally set to be much smaller than the friction force between the contact side and the contact surface, and thus may be omitted).

Further, in order to ensure that a slight displacement of the rotation shaft 200 in the axial direction does not cause the contact side of the nut 210 to completely disengage from the contact surface of the fixing bracket 206 (i.e., there is no limit of any friction at all) and that the abutment between the rotation member 208 and the fixing bracket 206 against each other is such that no slight play is thus generated to cause rattling to cause unexpected danger or damage to the reciprocating rotation mechanism 2, it is necessary to ensure that even in the above-described case, the contact side of the nut 210 can be kept in contact with the contact surface of the fixing bracket 206 and that the rotation member 208 and the fixing bracket 206 are also ensured to be in contact with or abut against each other, and therefore, the self-fastening mechanism 204 may additionally be provided with elastic means (not shown) to ensure contact of the contact side of the nut 210 against the contact surface of the fixing bracket 206. By way of example and not limitation, the resilient means may alternatively be a spring. In this case, the spring can be compressively disposed between the head (not shown) of the rotation shaft 200 and the rotation member 208, that is, one end of the spring abuts against the head of the rotation shaft 200 and the other end abuts against the rotation member 208, so that when a slight displacement of the rotation shaft 200 in the axial direction occurs, the compression force of the spring can ensure that the rotation member 208 is pressed against the fixing bracket 206 and thus contact of the contact side of the nut 210 with the contact surface of the fixing bracket 206. As an alternative embodiment, the spring can be configured to be penetrated by the rotation shaft 200 such that one end of the spring abuts against the head of the rotation shaft 200 and the other end abuts against the rotation member 208. It will be appreciated that when a slight displacement occurs as described above, the spring itself reduces in compression force due to elongation, so that on the one hand it is ensured that the contact side of the nut 210 remains in contact with the contact surface of the fixing bracket 206, but the friction therebetween still reduces.

As another alternative, the rotary member 208 may have a receiving portion (not shown) configured therein for receiving the spring such that the other end abuts against the bottom of the receiving portion in the rotary member 208 such that the spring is wrapped and protected. As an example of the receiving portion, the rotating member 208 includes therein an annular groove concentric with the through hole for receiving the rotating shaft 200 such that the spring can be inserted into the annular groove, the groove having a height smaller than that of the spring in a free state, and the annular groove can be covered by the head of the rotating shaft 200 when the rotating shaft 200 is assembled into the through hole.

Of course, as previously mentioned, the elastic means are not limited to springs, but may be extended to any elastic means capable of ensuring the contact of the contact side of the nut 210 with the contact surface of the fixed bracket 206 and of ensuring the abutment of the rotating member with the fixed bracket against each other, such as an elastomeric washer provided between the head of the rotating shaft 200 and the rotating member 208. Further, although described herein as being disposed between the head of the rotating shaft 200 and the rotating member 208, this is not limiting and as another possible embodiment that can be envisaged, the elastic means can be mounted independently of the rotating shaft 200 to ensure the above-described function is achieved.

Further, since the resilient means directly ensures the contact of the contact side of the nut 210 with the contact surface of the fixed bracket 206 and the contact pressure thereof, the critical condition when the contact side of the nut 210 rotates with respect to the contact surface of the fixed bracket 206 can be achieved by changing the compressive spring constant K of the present application for the selected reciprocating rotary mechanism. As will be appreciated, if the resilient means has a large coefficient of elasticity K of compression, the resilient force provided by the resilient means to the rotating member is significantly greater (assuming that any resilient means is equally compressed in the reciprocating rotary mechanism), thus resulting in a naturally greater pressure of the contacting side of the nut 210 against the contacting surface of the fixed bracket 206. Thus, for a rotating shaft and nut that experience the same degree of wear, a larger spring rate spring device will cause the contacting side of the nut 210 to be more pressed against the contacting surface of the stationary bracket 206 and thus more friction than a smaller spring rate spring device, and thus the nut is less prone to any displacement relative to the stationary bracket 206. Based on this, it is conceivable to determine the initial wear condition between the rotation shaft and the nut 210 when the contact side of the nut 210 is rotationally displaced with respect to the contact surface of the fixing bracket 206 by changing the different elastic coefficient K. Thus, for the same reciprocating rotary mechanism, it is possible to determine and control for which wear the nut 210 is capable of any rotational displacement with respect to the fixed bracket 206 by using elastic means of different elastic coefficients K. In other words, the resilient means of a greater spring coefficient ensures that the nut 210 is rotationally displaced relative to the fixed bracket 206 only with greater wear relative to the axis of rotation.

Further, another way of adjusting the critical condition of when the contact side of the nut 210 rotates relative to the contact surface of the stationary bracket 206 may be achieved, for example, by varying the relative smoothness of the contact side of the nut 210 and the contact surface of the stationary bracket 206. As an example, the higher the relative smoothness of the contacting side of the nut 210 and the contacting surface of the fixed bracket 206, the more likely the nut 210 is to be rotationally displaced relative to the fixed bracket 206, i.e. to the fixed bracket 206 with lower wear relative to the rotational axis.

In particular, in some cases, the elastic means may also be provided between the rotating member 208 and the fixed bracket 206. While this would result in the possibility that the rotating member 208 may no longer abut against the stationary support 206 when a slight displacement of the rotating shaft 200 in the axial direction occurs, it is ensured that the contact side of the nut 210 remains in contact with the contact surface of the stationary support 206, and that it is still possible that the elastic means are provided between the rotating member 208 and the stationary support 206 when the displacement is sufficiently small and when such a displacement can be adjusted in time. In this case, for example, annular grooves accommodating elastic means such as springs are provided on the rotary member 208 and the fixed bracket 206, respectively, concentrically with the through holes accommodating the rotary shaft 200 such that the springs are compressively held in the corresponding annular grooves on both the rotary member 208 and the fixed bracket 206 in the assembled state of the rotary member 208 and the fixed bracket 206.

Based on the above-described principle, it is believed that with the self-tightening mechanism 204 of the present application constructed as shown in fig. 2, it is possible to achieve a secure that the friction between the nut 210 and the stationary bracket 206 is not too low and thus a continuous press-to-assembly state between the rotating member 208 and the stationary bracket 206 is ensured.

Further, the number of ratchet teeth 212 provided on the circumferential outer side of the nut 210 in the self-tightening mechanism 204 can be configured as 10, 20, 30 or more or less without departing from the scope of the present utility model. It is envisioned that the number or circumferential arc (directly related to the number) of ratchet teeth 212 can be determined from the arc of rotational displacement that can drive the rotation shaft 200 to travel upon a single rotation of the rotation member 208 in a single direction, such that upon rotational displacement of the nut 210 (which is rotationally displaced with the rotation shaft 200) relative to the stationary bracket 206, ensuring that the rotational displacement spans the arc of at least one ratchet tooth enables the pawl to engage at least the next tooth to ensure a subsequent tightening effect between the rotation shaft 200 and the nut 210. As will be appreciated, if a single rotational displacement of the shaft fails to achieve a pawl ride-through engagement to at least the next ratchet, it is apparent that rotation of the shaft 200 in the other direction would also naturally fail to achieve a self-tightening effect. Thus, the circumferential arc occupied by the ratchet 212 is related to the arc of rotational displacement that the rotating member 208 is capable of driving the rotating shaft 200 to travel in a single rotation in a single direction, and is, by way of example, 1/2, 1/3 …, or any other integer fraction of the arc of maximum rotational displacement that the rotating member 208 is capable of driving the rotating shaft 200 to travel in a single rotation in a single direction, without departing from the scope of the utility model. It is apparent that the smaller the circumferential arc that the ratchet 212 occupies, the less difficult it is to achieve a pawl spanning engagement to at least the next ratchet.

Alternatively, the ratchet teeth 212 are identical to each other and are equally spaced apart in the circumferential direction of the nut. Alternatively, the circumferential curvature occupied by the ratchet teeth 212 is not equivalent. Alternatively, the ratchet teeth may be distributed at different intervals in the circumferential direction of the nut. Combinations of the various configurations described above are also included in embodiments of the present application.

Further, the self-tightening mechanism includes a pawl adjustment device 216 to adjust the pressure of the pawl 214 against the ratchet teeth 212 on the nut 210, which at least will affect the difficulty of the pawl 214 jumping teeth when engaging at least the next ratchet tooth 212 as the nut is rotated circumferentially. Specifically, the greater the pressure of the pawl 214 against the ratchet teeth 212, the greater the difficulty of tooth jump when the pawl 214 engages at least the next ratchet tooth 212.

By way of example, the pawl adjustment device 216 is a coil spring adjustment device that enables adjustment of the pressure of the pawl 214 against the ratchet teeth 212 on the nut by adjusting the pressure of the coil spring biasing the pawl 214 toward the nut 210. Further, the pawl adjustment means 216 may be manually adjustable and may be electrically adjustable. As shown in the embodiment of fig. 2, the pawl adjustment means 216 is a coil spring adjustment means. In the embodiment of fig. 2, the pawl 214 is disposed on an adjustable paddle 218 of a coil spring adjustment device. Specifically, in this embodiment, the adjustable paddle 218 includes a plate portion 220, wherein the pawl 214 is disposed to the side of the plate portion 220 to be in crimping engagement with the ratchet teeth 212 of the nut 210; a tab 222 that extends from the plate 220 to facilitate user adjustment of the adjustable paddle 218. The coil spring 224 in the coil spring adjusting device includes a coil body 226 and spring wires 228, 230 extending from both ends of the coil body 226 at angles, respectively, the ends of the two spring wires being engaged into a plate receiving hole 232 formed in the plate portion 220 and a bracket receiving hole 234 provided on the fixing bracket 206, respectively, so that both ends of the spring wires 228, 230 of the coil spring 224 can be fixed thereto, respectively. Then, the screw 236 is screwed to the fixing bracket 206 through the hollow hole of the spring body 226 of the coil spring 224 and the penetration hole provided in the plate portion 220 and is pressed against one end portion of the spring body 226 of the coil spring 224 by means of the screw head portion thereof. With this configuration, the user can adjust the pressure of the pawl provided on the adjustable dial against the ratchet by means of the coil spring by rotating the adjustable dial around the screw.

Alternatively, the pawl adjustment means 216 may be an electric actuator enabling adjustment of the pressure of the pawl 214 against the ratchet teeth 212 on the nut.

Further, the reciprocating rotary mechanism is a scissor head of an electric scissor. For this case, a more detailed description will be made with reference to fig. 3.

Fig. 3, which shows a cross-sectional view of an electric scissors employing the self-fastening mechanism for a rotary shaft according to the present utility model, will be described below.

The electric shears include at least a shears head 300 and a carriage 302 for supporting the shears head 300 of the electric shears 3, the shears head 300 including a fixed shear blade 304 fixedly assembled to the carriage 302 such that the fixed shear blade 304 is not displaced relative to the carriage 302 when the shears head 300 is operated; a movable scissor blade 306 that is reciprocally moved by rotation of a driving portion 308 (shown as a driving gear in this fig. 3) to realize an opening and closing function of the scissors; a rotation shaft 210 disposed in a through hole penetrating the movable scissor blade 306 and the bracket 302 such that the movable scissor blade 306 can rotationally move about the rotation shaft 200 with respect to the bracket 302 and the fixed scissor blade 304. The rotary shaft 200 includes a nut-like formation 312 at one end thereof that is integrally formed with the rotary shaft and is threadably secured at the other end by means of a nut 210 such that the rotary shaft 200 is defined in a through hole that extends through at least the movable scissor blade 306 and the carriage 302 (in the embodiment of fig. 3, the rotary shaft also extends through the fixed scissor blade and the drive gear, but this is not required) to achieve a press-fit assembly of the movable scissor blade 306 and the carriage 302. It should be understood herein that in the electric shears 3, since the fixed shears blade 304 and the bracket 302 do not undergo relative displacement when the electric shears 3 is operated, in this embodiment of the electric shears 3, the fixed shears blade 304 as a whole with the bracket 302 assembled thereto can be regarded as a fixed bracket as described above. Movable scissor blade 306 then corresponds to the rotating component described above. The shear head 300 as a whole may be considered to correspond to the reciprocating rotary mechanism described above. The scissor head 300 further includes a self-tightening mechanism 204 comprising a ratchet 212 disposed on a circumferential outer side of the nut 210 and a pawl 214 fixedly disposed on the bracket 302, wherein the nut 210 is configured to contact a surface of the bracket 302 such that a predetermined contact friction is established between the bracket 302 and the nut 210 when the scissor head 300 and the bracket 302 are in a normal operating state. In this embodiment, the side of the nut 210 that contacts the bracket 302 is referred to as the contact side and the surface of the bracket that contacts the nut is referred to as the contact surface.

As described above, the pawl 214 is fixedly provided to the bracket 302 so as not to be displaced any more and the pawl 214 engages the ratchet 212 of the nut, so that in this state, the nut 210 can be rotated only in the tightening direction of the nut 210 with respect to the pawl 214.

Further, the self-fastening mechanism further includes a pawl adjustment means as previously described with reference to fig. 2 to adjust the pressure of the pawl 214 against the ratchet teeth 212 on the nut 210, wherein the screw 236 is threaded through the hollow hole of the spring body 226 of the coil spring 224 and the through hole provided in the plate portion 220 to the fixed bracket 302 and is pressed against one end of the spring body 226 of the coil spring 224 by means of its screw head.

Further, the scissor head 300 also includes a resilient device 322 configured to ensure contact of the nut 210 to the bracket 302. As shown in detail in fig. 3, the elastic means 322 is optionally a spring which is arranged in compression between the nut-like formation 312 of the rotation shaft 210 and the movable scissor blade 304, i.e. one end of which abuts against the nut-like formation 312 of the rotation shaft 200 and the other end abuts against the movable scissor blade 304, so that the compression force of the spring is able to ensure that the movable scissor blade 304 is pressed against the bracket and thus that the contact side of the nut 210 is in contact with the bracket 302 when a slight displacement of the rotation shaft 200 in the axial direction occurs. As shown in fig. 3, the spring is configured to be penetrated by the rotating shaft 200 such that one end of the spring is configured against the nut-like structure 312 of the rotating shaft and the other end is against the movable scissor blade 304.

Further, as shown in fig. 3, the movable scissor blade 304 is configured with a receiving portion 324 for receiving the spring such that the other end abuts against the bottom of the receiving portion 324 such that the spring is wrapped and protected. As an example of the receiving portion 324, the movable scissor blade 304 includes therein an annular groove concentric with the through hole for receiving the rotation shaft 200 such that the spring can be inserted into the annular groove, the groove having a height smaller than a height of the spring in a free state, and the annular groove can be covered by a nut-like configuration of the rotation shaft when the rotation shaft is assembled into the through hole.

Although one application of the self-tightening mechanism of the present utility model is described in detail above with respect to electric shears as an example, it should be appreciated that the self-tightening mechanism disclosed herein may be employed with respect to any reciprocating rotary member that rotates about a rotary axis without departing from the scope of the present utility model.

Accordingly, the above-described embodiments of the present application are intended to be illustrative, and not restrictive. It will be understood by those skilled in the art that various modifications can be made to the above-described embodiments in light of the present disclosure without departing from the scope of the present disclosure, and such modifications or equivalents are intended to fall within the scope of the present disclosure.

Claims (10)

1. A self-fastening mechanism for a rotating shaft of a reciprocating rotating mechanism, the reciprocating rotating mechanism (2) comprising a fixed bracket (206) and a rotating member (208), the rotating shaft (200) being arranged in a through hole penetrating the rotating member (208) and the fixed bracket (206) such that the rotating member (208) is configured to move rotationally relative to the fixed bracket (206) around the rotating shaft (200), wherein the rotating shaft (200) comprises a nut-like configuration at one end thereof, which is integrally configured with the rotating shaft (200), and is screwed at the other end by means of a nut (210) such that the rotating member (208) is assembled pressed against the fixed bracket (206), wherein the rotating member (208) is configured to rotate reciprocally in the opposite direction;

Characterized in that the self-fastening mechanism (204) comprises a ratchet (212) provided on a circumferential outer side of the nut (210) and a pawl (214) fixedly provided on the fixing bracket (206) and engaging the ratchet (212), wherein the nut (210) is configured to contact a surface of the fixing bracket (206) in a normal operation state of the reciprocating rotation mechanism (2) such that a predetermined contact friction force is formed between the fixing bracket (206) and the nut (210).

2. The self-tightening mechanism according to claim 1, wherein the nut (210) is configured to be rotationally movable only in a single direction relative to the pawl (214) when the pawl (214) engages the ratchet (212), and wherein the single direction corresponds to a tightening direction of the nut (210).

3. The self-tightening mechanism according to claim 2, wherein the self-tightening mechanism (204) is configured such that when a friction force remaining between the threaded fixation between the rotation shaft (200) and the nut (210) is greater than a friction force between the nut (210) and a surface of the fixing bracket (206), then when the rotation member (208) rotates in the single direction, the rotation shaft (200) is driven to rotate in the single direction and the rotation shaft (200) will further drive the nut (210) to rotate together in the single direction.

4. Self-fastening mechanism according to claim 1 or 2, characterized in that the self-fastening mechanism (204) is further provided with an elastic means which is arranged in compression between the nut-like configuration of the rotation shaft and a rotation member (208) such that one end of the elastic means abuts against the nut-like configuration of the rotation shaft (200) and the other end abuts against the rotation member (208), and in that the rotation member (208) is configured with a receiving portion for receiving the elastic means such that the other end abuts against a bottom of the receiving portion in the rotation member (208), the receiving portion being arranged concentrically with the through hole and having a height which is smaller than a height of the elastic means in a free state.

5. A self-tightening mechanism according to claim 3, characterized in that the number of ratchet teeth (212) or circumferential arc is determined such that upon rotational displacement of the nut (210) relative to the fixed bracket (206), the rotational displacement is ensured to span the arc of at least one ratchet tooth such that the pawl engages at least the next ratchet tooth.

6. The self-tightening mechanism according to claim 5, wherein the circumferential arc occupied by the ratchet teeth (212) is any integer multiple of the arc of maximum rotational displacement that the rotating shaft (200) is driven to travel upon a single rotation of the rotating member (208) in the single direction.

7. The self-tightening mechanism according to claim 5, wherein the ratchet teeth (212) are identical to each other and equally spaced along the circumferential direction of the nut.

8. The self-tightening mechanism according to claim 1 or 2, characterized in that the pawl (214) comprises pawl adjustment means (216) to adjust the pressure of the pawl (214) against the ratchet teeth (212) on the nut (210).

9. The self-tightening mechanism according to claim 8, wherein the pawl adjustment device (216) is a coil spring adjustment device such that pressure of the pawl (214) against the ratchet teeth (212) on the nut (210) is adjusted by adjusting the pressure of the coil spring biasing the pawl (214) toward the nut (210).

10. An electric shears comprising at least a shears head (300) and a carriage (302), the carriage (302) for supporting the shears head (300) of the electric shears, the shears head (300) comprising a fixed shears blade (304) fixedly assembled to the carriage; a movable scissor blade (306) driven to reciprocate by a driving portion (308); a rotating shaft (200) arranged in a through hole penetrating at least the movable scissor blade (306) and the bracket (302) such that the movable scissor blade (306) is configured to move rotationally relative to the bracket (302) and the fixed scissor blade (304) around the rotating shaft (200), wherein the rotating shaft (200) comprises a nut-like configuration (312) integrally configured with the rotating shaft at one end thereof and is screwed at the other end by means of a nut (210) such that the movable scissor blade (306) is pressed against the fixed scissor blade (304) for assembly, characterized in that the scissor head (300) further comprises a self-fastening mechanism (204), wherein the self-fastening mechanism (204) comprises a ratchet tooth (212) arranged on a circumferential outer side of the nut (210) and a pawl (214) fixedly arranged on the bracket and engaging the ratchet tooth, wherein the nut (210) is configured to contact a surface of the bracket (302) such that a predetermined friction force is formed between the bracket (210) and the bracket (302) in a normal operation state of the scissor head (300).