CN108631476B

CN108631476B - Stepping motor

Info

Publication number: CN108631476B
Application number: CN201710166287.9A
Authority: CN
Inventors: 陈坤; 程涛; 汪靖
Original assignee: Vitesco Automotive Wuhu Co Ltd
Current assignee: Vitesco Automotive Wuhu Co Ltd
Priority date: 2017-03-20
Filing date: 2017-03-20
Publication date: 2024-06-07
Anticipated expiration: 2037-03-20
Also published as: CN108631476A

Abstract

The stepping motor provided by the invention comprises a magnetic conduction ring; the stator is sleeved in the magnetic conduction ring; the stator comprises a stator main body, pole pieces and coils; a stator rear cover configured at the rear end of the stator main body; the stator rear cover and the stator main body are integrally injection molded, and the stator main body and the pole piece are integrated in a cladding molding mode; the rear side of the stator rear cover is provided with an opening clamping groove, a contact pin is clamped in the opening clamping groove, a first end of the contact pin is connected with the end part of the coil, and a second end of the contact pin is used for being connected with a power supply in an inserting mode. According to the stepping motor provided by the invention, the pins are detachably clamped in the opening clamping grooves of the stator rear cover, so that the problems of deformation, displacement and the like of the pins when the pins are assembled on the stator rear cover can be avoided.

Description

Stepping motor

Technical Field

The invention relates to the technical field of motor engineering, in particular to a stepping motor.

Background

The stepper motor mainly comprises two types: one is a rotary stepper motor for outputting torque, and the other is a linear stepper motor for outputting linear motion. A linear stepper motor, which may also be referred to as a linear stepper motor, is a type of thrust device that converts electrical energy directly into linear mechanical motion. Linear stepper motors are widely used in the automotive field, for example for controlling the direction of illumination of a vehicle lamp or for controlling the steering of a wheel. With the progress of technology, linear stepper motors have a trend toward miniaturization and light weight.

Typical structures of the stepping motor of the prior art are as follows: the magnetic conduction ring made of metal is sleeved with a stator, and the stator comprises a stator main body, pole pieces and coils. The pole piece is embedded in the stator main body, the coil is wound on the stator main body, and the stator main body and the magnetic conduction ring are in non-rotatable fit. The rear end of the stator main body is provided with a stator rear cover which is used for fixing the contact pin. One end of the contact pin is connected with the end part of the coil, and the other end is connected with a power supply. The stator is sleeved with a rotor magnet, when the contact pin is connected with electricity, the coil generates a rotating magnetic field, and the rotor magnet rotates under the action of the rotating magnetic field. The middle of the rotor magnet is provided with a rotor shaft which rotates coaxially with the rotor magnet. The rotary stepper motor may output torque directly through the rotor shaft. The linear stepping motor is also provided with a threaded hole in the center of the rotor shaft, so that two ends of the rotor shaft are respectively supported by bearings, an adjusting head with limited circumferential rotation is arranged in the threaded hole of the rotor shaft in a penetrating mode, an external thread is arranged on the adjusting head and is meshed with the threaded hole, rotation of the rotor magnet is converted into linear motion of the adjusting head, and the front end of the adjusting head is used for applying force outwards.

The stepping motor (comprising a linear stepping motor and a rotary stepping motor) in the prior art is characterized in that the stator main body and the stator rear cover are integrally injection molded in the same injection mold by adopting the same plastic, and are combined with the pole piece and the contact pin into a whole in the molding process. Specifically, before plastic is injected into the inner cavities of the injection mold of the stator main body and the stator rear cover, a plurality of pole pieces and a plurality of contact pins are positioned in advance in the injection mold of the stator main body and the stator rear cover, and then the plastic is injected into the inner cavities of the mold, so that the stator main body, the stator rear cover, the pole pieces and the contact pins are combined into a whole in the injection mold.

When the plastic is molded in the injection mold, the pressure ratio in the mold is large, and the plastic can flow in a liquid state in the injection process. The small-size contact pin applied to the small linear stepping motor is small in size, and the small-size contact pin is impacted by pressure in the mold and fluid in the process of being integrated with injection molding plastic in the injection mold, so that deformation and even movement are easy to occur, and the molding qualification rate of a product is affected. In addition, the cooling process of the injection molded product after being taken out of the mold can shrink and deform, so that the contact pin receives larger deformation force, and the performance of the contact pin can be influenced.

In addition, in the linear stepping motor in the prior art, the rotor magnet, the rotor shaft and the adjusting head are coaxially arranged at the center of the magnetic conduction ring, so that the diameter of the magnetic conduction ring is larger, and the miniaturization design of the motor is not facilitated. When the requirement of reducing the diameter of the magnetic conduction ring is met, the diameter of the adjusting head needs to be made as small as possible. When the diameter of the adjusting head is greatly reduced, in order to meet the thrust requirement of the adjusting head, the material requirement of the adjusting head and the processing technology requirement of the adjusting head are relatively high, so that the cost of the adjusting head is greatly increased, and the cost of the linear stepping motor is greatly increased.

In addition, the prior art adjusting head is a metal shaft, and relatively large vibration and axial movement can be generated in the working process. To improve this, a spring is usually placed against one end of the adjustment head, and the preload of the rotor shaft by the spring increases the frictional wear of the rotor shaft.

Disclosure of Invention

The present invention is directed to a stepping motor for solving at least one of the above-mentioned problems of the stepping motor of the prior art.

The stepping motor provided by the invention comprises: a magnetic conductive ring; the stator is sleeved in the magnetic conduction ring; the stator comprises a stator main body, pole pieces and coils; a stator rear cover configured at the rear end of the stator main body; the stator is characterized in that the stator rear cover and the stator main body are integrally injection molded, and the stator main body and the pole piece are integrated in a cladding molding mode; the rear side of the stator rear cover is provided with an opening clamping groove, a contact pin is clamped in the opening clamping groove, a first end of the contact pin is connected with the end part of the coil, and a second end of the contact pin is used for being connected with a power supply in an inserting mode.

Further, the stepping motor further includes: a protective cover matched with the stator rear cover to seal the rear end of the magnetic conduction ring; the protective cover includes: an end cover part, which is covered on the opening of the opening clamping groove; and the arc-shaped combining part is configured at least at part of the edge of the end cover part and extends forwards to be combined with the rear end of the magnetic conduction ring.

Further, the stepping motor further includes: the connector body comprises an annular sleeve and a connecting end which is integrally injection molded with the annular sleeve; the connector body is configured such that at least a portion of the outer end surface of the end cap portion is not covered by the injection molding material of the connector body; the annular sleeve is coated on the outer peripheral surfaces of the assembled magnetic conduction ring, the stator rear cover and the protective cover in the injection molding process; the front end of the magnetic conduction ring protrudes out of the front end of the annular sleeve; the connecting end extends from the annular sleeve to a direction away from the center of the annular sleeve, and the connecting end is provided with an inner space for accommodating the second end of the contact pin.

Further, the end cap portion is located within the annular sleeve, and the rear end of the annular sleeve is provided with an opening towards the end cap portion.

Further, the stepping motor further includes: the rotor magnet is sleeved in the stator main body; the front shaft sleeve is non-rotatably arranged at the front end of the magnetic conductive ring relative to the central line of the magnetic conductive ring; a rotor shaft disposed on a center line of the rotor magnet and non-rotatably engaged with the rotor magnet; the front end of the rotor shaft extends into the central hole of the front shaft sleeve; the adjusting head is sleeved in the central hole of the front shaft sleeve in an axially sliding manner; the front end of the adjusting head extends out of the front end of the front shaft sleeve, and the rear end of the adjusting head is matched with the rotor shaft through a thread structure.

Further, the magnetic conduction ring is provided with a first cylindrical part and a first end wall positioned at the front end of the first cylindrical part, and the stator is sleeved in the first cylindrical part; the front shaft sleeve is provided with a second cylindrical part and a second end wall positioned at the rear end of the second cylindrical part; the second cylindrical part is penetrated in the central hole of the first end wall, and the adjusting head is in sliding fit with the central hole of the second cylindrical part; the second end wall has a portion clamped between the first end wall and the stator body; cooperating projections and recesses are provided between the second end wall and the first end wall and/or between the second end wall and the stator body to limit rotation of the front sleeve.

Further, a tab is disposed on the outer periphery of the second end wall and extends radially outwardly.

Further, the center hole diameter of the second end wall is smaller than the center hole diameter of the second cylindrical portion, and the middle portion of the rotor shaft is supported by the center hole of the second end wall; the front side of the stator rear cover is provided with a concave hole for supporting the rear end of the rotor shaft.

Further, the stepping motor also comprises a clamping plate provided with a U-shaped groove, and the clamping plate is positioned in the magnetic conduction ring and clamped between the second end wall and the stator main body; the rotor shaft is provided with an annular groove, and the U-shaped groove is clamped in the annular groove to limit the axial movement of the rotor shaft.

Further, one of the wall of the central hole of the second cylindrical portion and the outer peripheral wall of the adjusting head is provided with a guide groove extending in the axial direction, and the other is provided with a guide rib in sliding fit with the guide groove.

Further, a shaft shoulder propping against the second end wall is arranged on the rotor shaft, and a steel ball propping against the rear end of the rotor shaft is arranged in the concave hole.

Further, the rotor magnet is made of injection molding magnet, and the rotor shaft is a metal shaft; or the rotor magnet is made of injection molding magnet, and the rotor shaft is made of self-lubricating resin; the rotor magnet and the rotor shaft are integrated in an interference fit, bonding or cladding mode.

Further, the rear end face of the adjusting head is provided with a threaded hole extending along the axial direction, the part of the rotor shaft, which is positioned in the central hole of the front shaft sleeve, is provided with an external thread section, and the external thread section is meshed and matched with the threaded hole so as to convert the rotation of the rotor shaft into the linear motion of the adjusting head.

According to the stepping motor provided by the invention, the open clamping groove is formed in the rear side of the stator rear cover formed by injection molding, and the contact pin is arranged on the stator rear cover outside the injection mold in a mode of being detachably clamped with the open clamping groove, so that the contact pin is conveniently assembled on the stator rear cover, and the problem that in the prior art, the contact pin is easy to deform and displace when being integrated with the stator rear cover in the injection mold, so that a product is unqualified can be avoided. In addition, because the positioning problem of the contact pin does not need to be considered in the injection mold, the manufacturing difficulty and the manufacturing cost of the injection mold can be greatly reduced.

Drawings

Embodiments of the invention will be further described with reference to the accompanying drawings, in which:

fig. 1 shows a cross-sectional structure of a stepping motor provided in a first embodiment of the present invention;

figure 2 shows a perspective structure of a clamping plate of a stepping motor according to a first embodiment of the present invention,

Fig. 3 shows an exploded structure of a stepping motor provided in a first embodiment of the present invention;

Fig. 4 shows a perspective structure of a stepping motor according to a first embodiment of the present invention;

fig. 5 shows a perspective structure of a connector body of a stepping motor according to a first embodiment of the present invention;

Fig. 6 shows a structure in which a pin is clamped in an open clamping groove in a stepping motor according to a first embodiment of the present invention;

fig. 7 shows a structure in which a pin is separated from an open card slot in the stepping motor according to the first embodiment of the present invention; and

Fig. 8 shows a sectional structure of a stepping motor provided in a second embodiment of the present invention.

Detailed Description

Referring to fig. 1, a cross-sectional structure of a stepping motor provided in a first embodiment of the present invention is shown. As shown, the stepping motor includes: magnetic ring 1, stator 2, rotor magnet 3, rotor shaft 31, front axle sleeve 4, adjusting head 5, etc. It should be noted that, unless otherwise explained, directional terms "front" and "rear" in the embodiments of the present invention refer to the direction indicated by the arrow a in fig. 1 as the front, and refer to the direction indicated by the arrow B in fig. 1 as the rear.

In a miniaturized stepper motor, the magnetic ring 1 is preferably made of magnetic metal (e.g. iron), as known in the art. The stator 2 is sleeved in the magnetic conduction ring 1 and is in non-rotatable fit with the magnetic conduction ring 1. The stator 2 includes a stator body 21, pole pieces 22 embedded in the stator body 21, and coils 23 wound on the stator body 21. The stator body 21 is preferably injection molded from plastic. The pole pieces 22 are arranged in pairs, the outer periphery of each pole piece 22 is closely attached to the inner peripheral wall of the magnetic conductive ring 1, and a plurality of pole teeth are distributed on each pole piece 22 along the circumferential direction. A coil 23 is wound on the stator main body 21 between each pair of pole pieces 22, a stator rear cover 7 is further configured at the rear end of the stator main body 21, and the stator rear cover 7 is used for blocking the rear end of the stator main body 21 and can also partially block the rear end of the magnetic conduction ring 1. The stator back cover 7 is also used for mounting a plurality of pins 72. The first end (upper end in fig. 1) of each pin 72 is for connection to an end of a coil, and the second end 722 (lower end in fig. 1) is for connection to a power source.

As can also be seen in fig. 1 and 3, in this embodiment, the stator back cover 7 is made of the same material as the stator body 21 and is integrally injection molded. Before the stator main body 21 and the stator rear cover 7 are injection molded, each pole piece 22 is placed in advance in a cavity corresponding to the stator main body 21 in an injection mold, so that the stator main body 21 and the pole piece 22 are integrated by cladding. That is, the stator main body 21 and the stator rear cover 7 are molded and integrated with the pole piece 22 by one injection molding. Referring to fig. 6 and 7 in combination, the rear side of the stator rear cover 7 is provided with an open catch groove 71. The pin 72 is detachably clamped in the open clamping groove 71, and the pin 72 is preferably in interference fit with the open clamping groove 71. It will be appreciated that to fix the position of the pins 72, one pin 42 may be matingly snapped into engagement with a plurality of open detents 71.

In the stepping motor provided in this embodiment, the stator rear cover 7 and the stator main body 21 are integrally injection molded, the rear side of the injection molded stator rear cover 7 is provided with the open clamping groove 71, and the pin 72 is mounted on the stator rear cover 7 outside the injection mold by clamping with the open clamping groove 71, instead of being integrally combined with the stator rear cover 7 in the injection mold. In this way, the problem of defective products caused by pin deformation, pin shift and the like which are easily generated when the pin 72 is integrated with the stator rear cover 7 in the injection mold in the prior art can be avoided, and the manufacturing difficulty and the manufacturing cost of the injection mold can be greatly reduced. In addition, the pins 72 can be automatically clamped into the open clamping grooves 71 by using automation equipment, so that the pins 72 can be conveniently assembled on the stator rear cover 7, and the assembly quality of the pins 72 can be ensured. In addition, the pin 72 is engaged with the open-end locking groove 71, so that not only is the position of the pin 72 adjusted, but also the damaged pin 72 is replaced.

Referring to fig. 1 and 3 in combination, to avoid the connection between the first end of the pin 72 and the coil end being exposed and the pin 72 falling off from the open slot 71, the stepper motor further includes a protective cover 8, and the protective cover 8 cooperates with the stator rear cover 7 to seal the rear end of the magnetic conductive ring 1. The protective cover 8 has an end cap portion 81 that is provided over the opening of the open catch groove 71, and the end cap portion 81 is preferably perpendicular to the center line of the magnetically permeable ring 1. The end cap 81 can close the opening of the open catch 71 to prevent the pin 72 from coming off the opening of the open catch 71. The end cap portion 81 is preferably circular in shape, forming the rear end cap of the stepper motor. At part of the edge of the end cap 81, an arc-shaped coupling portion 82 extending forward is provided, and the arc-shaped coupling portion 82 is used for coupling with the rear end of the magnetic conductive ring 1, preferably in an interference fit manner, so that the space where the first end of the pin 72 is located is relatively closed. The other part of the edge of the end cap portion 81 may also be provided with a forwardly extending flange 83, the flange 83 being for engagement with the stator back cover 7.

Referring to fig. 1, 3 to 5 in combination, the stepping motor further includes a connector body 9, and the connector body 9 includes an annular sleeve 91 and a connection end 92 integrally injection-molded with the annular sleeve 91. The connector body 9 is configured such that at least part of the outer end face 811 of the end cap portion 81 is not covered with the injection molding material of the connector body 9.

Specifically, the annular sleeve 91 is coated on the outer peripheral surfaces of the assembled magnetic conductive ring 1, stator rear cover 7 and protective cover 8 in the injection molding process, so that the connector body 9, magnetic conductive ring 1, stator rear cover 7 and protective cover 8 are firmly integrated. As can be seen from the figure, the front end of the magnetic conducting ring 1 protrudes from the front end of the annular sleeve 91, so that the annular sleeve 91 does not completely cover the outer peripheral surface of the magnetic conducting ring 1, which is beneficial to heat dissipation of the motor. More importantly, the rear end of the annular sleeve 91 is configured such that at least a portion of the outer end surface 811 (e.g., a central region of the outer end surface 811) of the end cap portion 81 is not covered by the injection molding material, such that the end cap portion 81 is viewable outside of the stepper motor. In this embodiment, the end cap portion 81 is located within the annular sleeve 91, and the rear end of the annular sleeve 91 is provided with an opening 910 facing the end cap portion 81, the end cap portion 81 being visible through the opening 910. Preferably, the opening 910 may be a circular hole, and the diameter of the circular hole may be equal to the outer peripheral diameter of the circular end cap portion 81 or slightly smaller than the outer peripheral diameter of the circular end cap portion 81. It will be appreciated that in other embodiments, the end cap portion 81 may protrude outwardly from the rear end of the annular sleeve 91, or the end cap portion 81 may be made visible.

In the molding process of the connector main body 9 in the prior art, the injection molding plastic forming the connector main body 9 completely covers the outer surface of the protective cover 8 (including all the outer end surfaces of the end cover portion 81 of the protective cover 8), so that the end cover portion 81 of the protective cover 8 can receive a larger axial pressure in the molding die of the connector main body 9 and transmit the axial pressure to the stator rear cover 7, and further transmit the axial pressure to the rotor component and other components through the stator rear cover 7, which is easy to cause the deformation of the internal components of the motor and the clamping stagnation of the rotor shaft 31. As can be seen from fig. 1, in the present embodiment, by configuring the connector body 9 to a configuration in which the end cap portion 81 of the protective cover 8 is not covered with the injection molding material forming the connector body 9, the problems of deformation of the motor internal parts, rotor shaft seizing, and the like caused by subjecting the end cap portion 81 to a large axial pressure during the molding process of the connector body 9 can be avoided. In addition, by exposing the outer end surface 811 of the end cap 81, the outer end surface 811 of the end cap 81 can be used as a positioning surface in a mold when the connector body 9 is injection molded, which is particularly advantageous for molding the connector body 9.

The connection end 92 extends from the annular sleeve 91 in a direction away from the center of the annular sleeve 91. The connection end 92 has an interior space that receives the second end 722 of the pin 72 to protect the second end 722 of the pin 72 from deformation.

Referring again to fig. 1, in this embodiment, the rotor magnet 3 is housed in the stator body 21 and is driven to rotate by the stator 2. The rotor shaft 31 is disposed on the center line of the rotor magnet 3 and is non-rotatably fitted with the rotor magnet 3. Preferably, the material of the rotor magnet 3 is an injection-molded magnet, the rotor shaft 31 is a metal shaft, and the rotor magnet 3 and the rotor shaft 31 can be integrated by interference fit, adhesion or cladding. Alternatively, in other embodiments, the material of the rotor magnet 3 is an injection-molded magnet, the material of the rotor shaft 31 is a self-lubricating resin (for example, polyphenylene sulfide mixed with a solid lubricant is used), and the rotor magnet 3 and the rotor shaft 31 may be integrated by interference fit or adhesion after injection molding respectively, or one of them is integrated by cladding molding after injection molding.

A front sleeve 4 is disposed at the front end of the magnetically conductive ring 1, and the front sleeve 4 is disposed at the front end of the magnetically conductive ring 1 so as to be non-rotatable with respect to the center line of the magnetically conductive ring 1. The front end of the rotor shaft 31 extends into the central bore of the front sleeve 4. An adjusting head 5 is arranged in the central hole of the front shaft sleeve 4, and the circumferential rotation of the adjusting head 5 is limited, so that the adjusting head 5 can be axially and slidably sleeved in the central hole of the front shaft sleeve 4. That is, the stepping motor of the present embodiment is more specifically a linear stepping motor. As can be seen from the figure, the front end of the adjusting head 5 extends from the front end of the front shaft sleeve 4, the rear end of the adjusting head 5 is located in the central hole of the front shaft sleeve 4, and the rear end of the adjusting head 5 is matched with the rotor shaft 31 through a screw structure. Preferably, in the present embodiment, a screw hole 50 extending in the axial direction is provided on the rear end surface of the adjustment head 5. The portion of the rotor shaft 31 located in the central hole of the front boss 4 is provided with an external thread section which is engaged with the threaded hole 50 to convert the rotation of the rotor shaft 31 into linear motion of the adjustment head 5 and apply a push-pull force to the force receiving member through the front end of the adjustment head 5. It will be appreciated that in other embodiments, the male threaded section may be provided at the rear end of the adjustment head 5 and the threaded bore provided on the rotor shaft 31. Preferably, the adjustment head 5 may be made of injection-molded plastic.

The working principle of the stepping motor provided by the embodiment is as follows:

After the contact pin 72 is plugged into a power supply, the coil 23 is electrified, and a multipolar closed rotating magnetic field is formed by utilizing part of the magnetic conduction ring 1 and pole teeth on the pole piece 22, so that the rotor magnet 3 drives the rotor shaft 31 to rotate together under the action of the rotating magnetic field. Because the rotation of the adjusting head 5 is limited, under the action of the screw structure between the adjusting head 5 and the rotor shaft 31, the rotation of the rotor shaft 31 is converted into the linear motion of the adjusting head 5, so that the front end of the adjusting head 5 stretches and contracts relative to the front shaft sleeve 4, and the pushing and pulling force is applied to the stress piece connected with or abutted against the front end of the adjusting head 5 while the adjusting head 5 stretches and contracts.

The stepping motor is beneficial to reducing the radial size of the magnetic conduction ring 1 by moving out the screw thread transmission structure between the rotor shaft 31 and the adjusting head 5 to the outside of the magnetic conduction ring 1, and the diameter of the adjusting head 5 is not greatly reduced, so that the costs of the adjusting head 5 and the stepping motor are not too high, and the problem that the linear stepping motor in the prior art cannot be reduced in diameter of the magnetic conduction ring and reduced in cost of the motor is solved. In addition, by arranging the external screw thread in the screw transmission structure between the rotor shaft 31 and the adjustment head 5 on the rotor shaft 31 and arranging the internal screw thread in the adjustment head 5, the manufacturing difficulty and cost of the rotor shaft 31 and the adjustment head 5 can be further reduced.

The preferred structure of the magnetic ring 1 and the front sleeve 4 is shown in this embodiment. As shown in fig. 1, the magnetic flux ring 1 has a first cylindrical portion 11 and a first end wall 12 located at the front end of the first cylindrical portion 11, the stator 2 is fitted in the first cylindrical portion 11, and the outer peripheral edge of the pole piece 22 is abutted against the inner peripheral wall of the first cylindrical portion 11. The front boss 4 has a second cylindrical portion 41 and a second end wall 42 located at the rear end of the second cylindrical portion 41. As can be seen in fig. 1, the second cylindrical portion 41 is preferably located at a position between the outer periphery and the inner periphery of the second end wall 42. The second cylindrical portion 41 is pierced in the central hole of the first end wall 12, and the adjustment head 4 is slidably fitted in the central hole of the second cylindrical portion 41. The second end wall 42 has a portion clamped between the first end wall 12 and the stator body 21 of the stator 2to achieve axial positioning of the front sleeve 4.

To limit the rotation of the front sleeve 4, cooperating projection and recess arrangements may be provided between the second end wall 42 and the first end wall 12 and/or between the second end wall 42 and the stator body 21 of the stator 2. The projection may be, for example, an end tooth provided on an end face of the second end wall 42, and the recess may be a concave structure provided on the first end wall 12 or the stator body 21 for receiving the end tooth. Alternatively, as shown in fig. 3, the boss 421 in this embodiment is preferably provided on the outer periphery of the second end wall 42 and extends radially outwardly, and the recess 20 is provided on the stator body 21 and is adapted to receive the boss 421. As can be seen from the figure, the number of the protrusions 421 and the recesses 20 is two, and it is understood that the number of the protrusions 421 and the recesses 20 may be one or more. In addition, it will be appreciated that in other embodiments not shown, the recess 20 may also be disposed on the wall surface of the first end wall 12 facing the second end wall 42 when the projection 421 is disposed on the outer periphery of the second end wall 42 and extends radially outwardly. Furthermore, it will be appreciated that there are a wide variety of configurations of the projections and recesses, provided that the front sleeve 4 is restrained from rotating relative to the centre line of the magnetic ring 1.

The preferred structure for limiting the relative rotation of the adjustment head 5 and the front sleeve 4 is also shown in this embodiment. As shown in fig. 3, a guide groove 410 extending in the axial direction is provided on the wall of the center hole of the second cylindrical portion 41, and a guide rib 510 slidably engaged with the guide groove 410 is provided on the outer peripheral wall of the adjustment head 5. It will be appreciated that in other embodiments the positions of the guide grooves and ribs on the second cylindrical portion 41 and the adjustment head 5 may be interchanged. In addition, the number of the guide grooves 410 and the guide ribs 510 can be set according to actual needs.

Referring again to fig. 1, the center hole diameter of the second end wall 42 in this embodiment is smaller than the center hole diameter of the second cylindrical portion 41, so that the middle portion of the rotor shaft 31 is pierced in the center hole of the second end wall 42 and can be supported by the center hole of the second end wall 42. At the same time, the second end wall 42 may also serve to limit the retracted position of the adjustment head 5. A concave hole 70 for supporting the rear end of the rotor shaft 31 is disposed on the front side of the stator rear cover 7.

A preferred embodiment of limiting the axial movement of the rotor shaft 31 is also shown in this embodiment. Referring to fig. 1 to 3 in combination, the stepper motor further comprises a clamping plate 6 provided with a U-shaped groove 60, the clamping plate 6 being located within the magnetic ring 1 and clamped between the second end wall 42 and the stator body 21 of the stator 2. An annular groove 310 is arranged on the rotor shaft 31, and the U-shaped groove 60 of the clamping plate 6 is clamped in the annular groove 310 to limit the axial movement of the rotor shaft 31, so that the axial movement of the rotor shaft 31 is effectively controlled. By arranging the clamping plate 6, an additional spring piece can be not arranged at the rear end of the rotor shaft 31, and abrasion caused by the pretightening force applied to the rotor shaft 31 by the spring piece can be effectively avoided. Preferably, the clamping plate 6 is made of a metal material with self-lubricating performance or is formed by injection molding of resin with self-lubricating performance, and the annular groove 310 and the U-shaped groove 60 are in clearance fit.

The assembly process of the stepping motor provided in the first embodiment of the present invention is as follows: the rotor magnet 3 is integrated with the rotor shaft 31 by injection molding or interference fit. The stator body 21 and the stator rear cover 7 are integrally injection molded, and the pole piece 22 is embedded in the stator body 21 in the molding process. The pin 72 is inserted into the open locking groove 71 of the stator back cover 7, the coil 23 is wound around the stator main body 21, and the end of the coil 23 is connected to the first end of the pin 72. After the chucking plate 6 is inserted into the annular groove 310 of the rotor shaft 31, the rotor magnet 3 is placed inside the stator main body 21, and the rear end of the rotor shaft 31 is inserted into the concave hole 70 of the stator rear cover 7. The adjusting head 5 is sleeved in the front shaft sleeve 4, the adjusting head 5 is in threaded engagement with the rotor shaft 31, and the front shaft sleeve 4 is installed on the stator main body 21 in place. Then, the magnetic flux ring 1 is attached to the front end of the stator main body 21, and the protective cover 8 is attached to the rear end of the stator rear cover 7. Then, the above-mentioned assembled components are subjected to partial housing injection molding, the connector body 9 is injection molded, and the molding process of the connector body 9 is reliably combined with the magnetic conductive ring 1, the stator rear cover 7 and the protective cover 8, so that the end cover portion 81 of the protective cover 8 is exposed.

Referring now to fig. 8, a second preferred embodiment of the present invention is shown. The main difference between this second preferred embodiment and the first preferred embodiment described above is the axial limit of the rotor shaft 31. As shown, the second preferred embodiment is not provided with a card, but a shoulder 311 abutting against the front boss 4 is provided on the rotor shaft 31 to restrict the forward movement of the rotor shaft 31; a steel ball 61 abutting against the rear end of the rotor shaft 31 is installed in the concave hole 70 of the stator rear cover 7 for restricting the rearward movement of the rotor shaft 31. The small contact area of the steel balls 61 with the rotor shaft 31 is advantageous in reducing friction of the rotor shaft 31. The limiting mode is particularly suitable for motors with the rotor shaft 31 and the rotor magnet 3 made of plastics, because the rotor shaft 31 and the rotor magnet 3 made of plastics are lighter in weight, and under the vibration condition, the axial impact force is smaller, the abrasion is smaller, and the requirement can be met by axially limiting the rotor shaft 3 through the shaft shoulder 311 and the steel ball 61.

In summary, the stepping motor provided by the embodiment of the invention can be supported without using the ball bearing, has simple manufacturing and assembling processes, and reduces manufacturing cost. By moving out the screw transmission structure between the rotor shaft 31 and the adjusting head 5 to the outside of the magnetic conduction ring 1, the radial dimension of the magnetic conduction ring 1 of the linear stepping motor is reduced, and the cost is not increased greatly. The pin 72 is detachably clamped in the opening clamping groove 71 of the stator rear cover 7, so that the problems that the pin 72 is deformed, displaced and the like when the pin 72 is integrated with the stator rear cover 7 through cladding molding in the rotary stepping motor and the linear stepping motor in the prior art can be avoided. The rotor magnet 3, the rotor shaft 31 and the adjusting head 5 can all be injection molded, so that the stepping motor has lighter weight and less vibration. In addition, the connector main body 9 is formed by partial injection molding, and the end cover part 81 of the protective cover 8 is exposed, so that the stress deformation of the internal structure of the motor can be avoided, and the positioning during injection molding is facilitated.

It is to be understood that the above embodiments of the present invention are merely exemplary embodiments employed to illustrate the principles of the present invention and that the present invention is not limited thereto. Various modifications and improvements may occur to those skilled in the art without departing from the spirit and the substance of the invention, and such modifications and improvements are considered to be within the scope of the invention. The scope of the invention is to be defined only by the meaning of the language of the following claims and the equivalents thereof.

Claims

1. A stepper motor, comprising: a magnetic conductive ring (1); the stator (2) is sleeved in the magnetic conduction ring (1); the stator (2) comprises a stator main body (21), pole pieces (22) and coils (23); a stator rear cover (7) disposed at the rear end of the stator main body (21); the stator is characterized in that the stator rear cover (7) and the stator main body (21) are integrally injection molded, and the stator main body (21) and the pole piece (22) are integrated in a cladding molding mode; an opening clamping groove (71) is formed in the rear side of the stator rear cover (7), a contact pin (72) is clamped in the opening clamping groove (71), a first end of the contact pin (72) is connected with the end of the coil (23), and a second end (722) of the contact pin (72) is used for being connected with a power supply in an inserting mode;

The stepper motor further includes:

A protective cover (8) matched with the stator rear cover (7) to block the rear end of the magnetic conduction ring (1), wherein the protective cover (8) comprises an end cover part (81) which is covered on an opening of the opening clamping groove (71); and

-A connector body (9), the connector body (9) being configured such that at least part of an outer end surface (811) of the end cap portion (81) is not covered by injection moulding material of the connector body (9).

2. The stepping motor according to claim 1, wherein,

The protective cover (8) further includes an arc-shaped coupling portion (82) disposed at least at a portion of the edge of the end cover portion (81) and extending forward to be coupled with the rear end of the magnetically permeable ring (1).

3. The stepping motor according to claim 2, wherein,

The connector body (9) comprises an annular sleeve (91) and a connecting end (92) which is integrally injection molded with the annular sleeve (91);

the annular sleeve (91) is coated on the outer peripheral surfaces of the assembled magnetic conduction ring (1), the stator rear cover (7) and the protective cover (8) in the injection molding process; the front end of the magnetic conduction ring (1) protrudes out of the front end of the annular sleeve (91);

The connection end (92) extends from the annular sleeve (91) in a direction away from the center of the annular sleeve (91), and the connection end (92) has an interior space for receiving the second end (722) of the pin (72).

4. A stepper motor according to claim 3, characterized in that the end cap part (81) is located inside the annular sleeve (91), the rear end of the annular sleeve (91) being provided with an opening (910) towards the end cap part (81).

5. The stepper motor of claim 1, further comprising:

a rotor magnet (3) sleeved in the stator main body (21);

a front sleeve (4) which is non-rotatably disposed at the front end of the magnetic ring (1) with respect to the center line of the magnetic ring (1);

A rotor shaft (31) which is disposed on the center line of the rotor magnet (3) and is non-rotatably engaged with the rotor magnet (3); the front end of the rotor shaft (31) extends into a central hole of the front shaft sleeve (4);

the adjusting head (5) is sleeved in the central hole of the front shaft sleeve (4) in an axially sliding manner;

The front end of the adjusting head (5) extends out of the front end of the front shaft sleeve (4), and the rear end of the adjusting head (5) is matched with the rotor shaft (31) through a thread structure.

6. The stepping motor according to claim 5, wherein,

The magnetic conduction ring (1) is provided with a first cylindrical part (11) and a first end wall (12) positioned at the front end of the first cylindrical part (11), and the stator (2) is sleeved in the first cylindrical part (11);

The front sleeve (4) has a second cylindrical portion (41) and a second end wall (42) at the rear end of the second cylindrical portion (41);

The second cylindrical part (41) is penetrated in the central hole of the first end wall (12), and the adjusting head (5) is in sliding fit with the central hole of the second cylindrical part (41); the second end wall (42) has a portion clamped between the first end wall (12) and the stator body (21); matching projections (421) and recesses (20) are provided between the second end wall (42) and the first end wall (12) and/or between the second end wall (42) and the stator body (21) to limit the rotation of the front sleeve (4).

7. The stepper motor according to claim 6, characterized in that the projection (421) is arranged on the outer periphery of the second end wall (42) and extends radially outwards.

8. The stepping motor according to claim 6, wherein,

The center hole diameter of the second end wall (42) is smaller than the center hole diameter of the second cylindrical portion (41), and the middle portion of the rotor shaft (31) is supported by the center hole of the second end wall (42);

a concave hole (70) for supporting the rear end of the rotor shaft (31) is arranged on the front side of the stator rear cover (7).

9. The stepper motor according to claim 6, further comprising a clamping plate (6) provided with a U-shaped groove (60), said clamping plate (6) being located inside said magnetically permeable ring (1) and clamped between said second end wall (42) and said stator body (21); an annular groove (310) is formed in the rotor shaft (31), and the U-shaped groove (60) is clamped in the annular groove (310) to limit axial movement of the rotor shaft (31).

10. The stepping motor according to claim 6, wherein one of a wall of the center hole of the second cylindrical portion (41) and an outer peripheral wall of the adjustment head (5) is provided with a guide groove (410) extending in an axial direction, and the other is provided with a guide rib (510) slidably fitted with the guide groove (410).

11. The stepping motor according to claim 8, wherein a shoulder (311) abutting against the second end wall (42) is provided on the rotor shaft (31), and a steel ball (61) abutting against the rear end of the rotor shaft (31) is mounted in the concave hole (70).

12. The stepping motor according to claim 5, wherein,

The rotor magnet (3) is made of injection molding magnet, and the rotor shaft (31) is a metal shaft; or the material of the rotor magnet (3) is injection-molded magnet, and the material of the rotor shaft (31) is self-lubricating resin;

the rotor magnet (3) and the rotor shaft (31) are integrated in an interference fit, adhesion or cladding mode.

13. Stepper motor according to claim 5, characterized in that the rear end face of the adjustment head (5) is provided with an axially extending threaded hole (50), and that the part of the rotor shaft (31) located in the central hole of the front sleeve (4) is provided with an external threaded section, which external threaded section cooperates in engagement with the threaded hole (50) to convert the rotation of the rotor shaft (31) into a linear movement of the adjustment head (5).