ELECTROMAGNETIC ACTUATOR

An electromagnetic actuator comprises a housing, front and rear magnetic poles, and a guide sleeve. The front magnetic pole is fixed to the housing, the housing has a cavity, the cavity has a closed end and an open end, the open end is closed by the front magnetic pole, and the rear magnetic pole and the guide sleeve are mounted in the cavity; the guide sleeve has a first end facing the open end, a second end facing the closed end, an elastically deformable flange at the first end, and a radially stepped surface at an axially middle portion facing the closed end; the rear magnetic pole is axially abutted between the radially stepped surface and the closed end; and the flange is elastically abutted against the front magnetic pole, such that the guide sleeve and the rear magnetic pole are axially positioned with respect to the housing.

TECHNICAL FIELD

The present disclosure relates to the technical field of electromagnetic actuators. Specifically, the present disclosure relates to an electromagnetic actuator having an improved mounting manner.

BACKGROUND

In the modern industry, electromagnetic actuators are widely used. The electromagnetic actuators use magnetic forces, such as those generated by solenoids, to drive actuating mechanisms, thereby controlling the movement of mechanical components. For example, in an engine of a motor vehicle, an electromagnetic actuator may be used to control and adjust the valve lift of the engine.

FIG.1shows a design manner of an electromagnetic actuator in the prior art. This electromagnetic actuator comprises a housing10, a front magnetic pole20, a rear magnetic pole30, a skeleton40, a guide sleeve50, an armature60, and the like. The cavity enclosed by the housing10and the front magnetic pole20is used for mounting other components. The skeleton40for mounting a coil is made of plastic, such as PA66GF30, and other components are made of metal materials. During assembly, after the housing10and the front magnetic pole20are fixed together, the skeleton40is pressed between the housing10and the front magnetic pole20for being fixed with respect to the housing10, and at the same time, the rear magnetic pole30is pressed between the housing10and a flange on the skeleton40. After being pressed, a rib on the flange of the skeleton40will collapse and be deformed, thereby fixing the rear magnetic pole30.

High temperatures are sometimes generated inside the electromagnetic actuator. At a high temperature, the material of the skeleton40will expand, causing the rib on the flange to be continuously compressed and deformed. However, when the temperature returns to normal, the deformed rib cannot return to an original state because the skeleton40is made of plastic. Therefore, the rear magnetic pole30can no longer be pressed in an axial direction by the housing10and the skeleton40, so that the rear magnetic pole30cannot be maintained in contact with the housing10. A spacing between the rear magnetic pole30and the housing10may cause an electromagnetic force loss. When the spacing between the rear magnetic pole30and the housing10is 0.1 mm, the electromagnetic force loss will exceed 10%. A larger spacing indicates a greater electromagnetic force loss. This significantly affects the actuation capability of the electromagnetic actuator.

SUMMARY

Therefore, the technical problem to be solved by the present disclosure is to provide an improved electromagnetic actuator.

The above-mentioned technical problem is solved by the electromagnetic actuator according to the present disclosure. The electromagnetic actuator comprises a housing, a front magnetic pole, a rear magnetic pole, and a guide sleeve, wherein the front magnetic pole is fixed to the housing, the housing has a cavity, the cavity has a closed end and an open end axially opposite to each other, the open end is closed by the front magnetic pole, and the rear magnetic pole and the guide sleeve are mounted in the cavity; the guide sleeve has a first end facing the open end and a second end facing the closed end; the guide sleeve has an elastically deformable flange at the first end, and a radially stepped surface at an axially middle portion facing the closed end; the rear magnetic pole is axially abutted between the radially stepped surface and the closed end; and the flange is elastically abutted against the front magnetic pole, such that the guide sleeve and the rear magnetic pole are axially positioned with respect to the housing. Since the flange is elastically abutted against the front magnetic pole, when thermal expansion and contraction occur in the components in the electromagnetic actuator at different temperatures, the flange can compensate for the spacing formed between the guide sleeve and the front magnetic pole and between the rear magnetic pole and the housing through elastic deformation. Different from the fixation implemented by crushing plastic materials in the prior art, the deformation generated on the pressed flange when the spacing becomes smaller can return to an original shape when the spacing becomes larger again, thereby automatically adapting to the changes of the spacing. This ensures that the axial positioning of internal components remains stable during operation of the electromagnetic actuator. Usually, the guide sleeve is a thin-walled structure made of metal, so that the flange integrally formed on the guide sleeve has a good elastic deformation capability, which is sufficient to meet the above functional requirements.

According to an example embodiment of the present disclosure, the flange may extend obliquely toward the radially outer side with respect to the radial direction, so that the outer edge of the flange can be abutted against the front magnetic pole. Therefore, the flange has a structure similar to a diaphragm spring, which gives the flange the good elastic deformation capability.

According to an example embodiment of the present disclosure, the rear magnetic pole may have a third end facing the open end and a fourth end facing the closed end, the third end may be abutted against the radially stepped surface, and the fourth end may be abutted against the closed end. Therefore, the rear magnetic pole is axially integrally abutted between the radially stepped surface and the closed end.

According to an example embodiment of the present disclosure, the third end and/or the fourth end may have a flat end surface, thereby ensuring that the rear magnetic pole can be stably abutted against the radially stepped surface and/or the closed end.

According to an example embodiment of the present disclosure, the electromagnetic actuator may further comprise a skeleton for mounting a coil, and the skeleton may be fixed to the radially outer side of the rear magnetic pole. Therefore, the skeleton can be positioned in the cavity by means of the rear magnetic pole, eliminating the need for a direct fit relationship between the skeleton and the housing or the front magnetic pole.

According to an example embodiment of the present disclosure, the skeleton may be fixed to the radially outer side of the rear magnetic pole through overmolding. The skeleton may be made of plastic, and the rear magnetic pole may be made of metal, and the two can be conveniently fixed together through overmolding.

According to an example embodiment of the present disclosure, the skeleton may have a groove on an end surface facing the open end, and the flange may be accommodated in the groove. Preferably, the flange may be not in contact with the groove within a predetermined elastic deformation range of the flange. Especially, when the flange deflects toward the closed end under an axial pressure, the outer edge of the flange will be close to the side wall and the bottom wall of the groove, ensuring that the flange is not in contact with the side wall or the bottom wall of the groove within the predetermined elastic deformation range by design, thereby preventing interference in the elastic deformation of the flange.

DETAILED DESCRIPTION

Specific implementations of an electromagnetic actuator according to the present disclosure will be described below with reference to the accompanying drawings. The following detailed description and drawings are intended to exemplarily illustrate the principle of the present disclosure. The present disclosure is not limited to the described embodiments.

According to an example embodiment of the present disclosure, provided is an electromagnetic actuator capable of providing an actuation function through electromagnetic force. For example, this electromagnetic actuator may be used in a valve mechanism of an engine, to control on and off of the valve.

FIG.2a,FIG.2b, andFIG.2cshow schematic diagrams of an exemplary embodiment of an electromagnetic actuator according to the present disclosure. As shown inFIG.2a, the electromagnetic actuator mainly comprises a housing10, a front magnetic pole20, a rear magnetic pole30, a skeleton40, a guide sleeve50, an armature60, and the like. The housing10is made of metal and has an axially extending cavity, wherein one end of the cavity is a closed end and the other end is an open end. The front magnetic pole20is fixed to the housing10and closes the cavity. Other components are encapsulated in the cavity by the housing10and the front magnetic pole20.

The skeleton40is a cylindrical component made of plastic and other materials, whose axis is arranged along the axial direction of the cavity. A coil is mounted inside the skeleton, and the coil can generate an electromagnetic field when energized. The rear magnetic pole30is a cylindrical component made of metal materials, which is mounted substantially coaxially on the radially inner side of the skeleton40.

The guide sleeve50is a cylindrical component made of metal, which has a thin-walled structure. The guide sleeve50is coaxially mounted on the radially inner side of the skeleton40. The guide sleeve50has a first end51and a second end52axially opposite to each other. The first end51faces the open end of the cavity, and the second end52faces the closed end of the cavity.

The armature60is also a cylindrical component made of metal materials. The armature60is coaxially mounted on the radially inner side of the guide sleeve50and can axially move with the guidance of the inner wall of the guide sleeve50. A columnar push rod70is fixedly mounted on the radially inner side of the armature60, so as to axially move with the armature60. One axial end of the push rod70penetrates through a through hole on the front magnetic pole20for extending out of the front magnetic pole20when moving, so as to push other components. A spring80is axially abutted between the front magnetic pole20and the armature60. When the coil is powered off or the generated electromagnetic force is insufficient to overcome the elastic force of the spring80, the spring80can push the armature60to move toward the second end52of the guide sleeve50.

FIG.2cshows an enlarged view ofFIG.2aat the first end51of the guide sleeve50. As shown inFIG.2c, the first end51of the guide sleeve50is an open end, and the guide sleeve50has a flange53extending out toward the radially outer side at the first end51. The flange53may be an everted edge integrally formed with the guide sleeve50. The flange53may have a circular contour. The flange53extends obliquely toward the radially outer side with respect to the radial direction, to form a funnel-shaped or trumpet-shaped structure. The oblique direction of the flange53causes the outer edge of the flange53to be further offset with respect to the inner edge in the direction toward the open end of the housing10. Therefore, when the front magnetic pole20is fixed to the housing10, the outer edge of the flange53will be abutted against the bottom surface of the front magnetic pole20, while an area of the radially inner side of the flange53will not be in a direct contact with the front magnetic pole20.

FIG.2bshows an enlarged view ofFIG.2aat an axially middle portion of the guide sleeve50. As shown inFIG.2b, the guide sleeve50has a radially extending section at the axially middle portion, which axially divides the guide sleeve50into two parts with different radii. The radius of a first part close to the open end of the housing10is greater than that of a second part close to the closed end. A section extending radially between the two parts forms a transition stepped portion between the two parts, and the outer side surface of the transition stepped portion forms a radially stepped surface54facing the closed end of the housing10.

The rear magnetic pole30surrounds the radially outer side of the second part of the guide sleeve50and is axially abutted between the radially stepped surface54and the closed end of the housing10. The rear magnetic pole30has a third end and a fourth end axially opposite to each other, wherein the third end is axially abutted against the radially stepped surface54, and the fourth end is axially abutted against the closed end of the housing10. Both the third end and the fourth end may have a flat end surface for being stably abutted against the radially stepped surface54and the closed end of the housing10.

When the rear magnetic pole30and the guide sleeve50are mounted inside the housing10via the front magnetic pole20, the guide sleeve50is always in a state of being oppositely squeezed by the front magnetic pole20and the rear magnetic pole30, so that the flange53maintains elastic deformation. The elastic force generated by the elastically deformed flange53acts on the front magnetic pole20on the one hand, and acts on the rear magnetic pole30via the radially stepped surface54on the other hand, so that the guide sleeve50and the rear magnetic pole30are axially pressed together between the front magnetic pole20and the closed end of the housing10, thereby achieving axial positioning of the two in the cavity. When dimensional changes occur in the components of the electromagnetic actuator due to, for example, temperature changes, the flange53can adapt to such dimensional changes through elastic deformation, so that the guide sleeve50and the rear magnetic pole30can always be stably pressed between the front magnetic pole20and the closed end of the housing10without causing an axial spacing.

The rear magnetic pole30may be further used to position the skeleton40. Specifically, the rear magnetic pole30and the skeleton40may be fixed together. For example, the rear magnetic pole30is made of metal, and the skeleton40is made of plastic, so the skeleton40may be fixed to the radially outer side of the rear magnetic pole30through overmolding. In this case, since an axial location of the rear magnetic pole30is limited, an axial location of the skeleton40is also limited. At this time, there may be an axial spacing between at least one end of the skeleton40(especially the end facing the closed end) and the closed end or the front magnetic pole20, so as to allow the skeleton40to move slightly with respect to the housing10when elastic deformation occurs on the flange53. Compared with the prior art, since the skeleton40does not need to form a flange and a rib any longer, the structure is significantly simplified, which helps to reduce the production cost of the electromagnetic actuator.

As shown inFIG.2b, a groove41may be further formed on an end surface of the skeleton40facing the open end. The groove41is axially recessed from the end surface of the skeleton40and may have, for example, a circular outer contour corresponding to that of the flange53. The flange53is accommodated in the groove41. The dimension of the groove41allows the elastic deformation of the flange53inside the groove without hindrance. Specifically, the flange53is never in contact with the inner wall of the groove41within a predetermined elastic deformation range of the flange53. Particularly, the outer edge of the flange53is not in contact with the side wall and the bottom wall of the groove53. This means that the radial dimension of the groove41should be slightly greater than the maximum radial dimension of the flange53. The predetermined elastic deformation range of the flange53refers to all possible elastic deformation ranges of the flange53under all operation conditions allowed by design.

The embodiment of the present disclosure aims to achieve stable mounting of the guide sleeve50and the rear magnetic pole30through the elastic flange53of the guide sleeve50. On this basis, various changes can be made to other structural components of the electromagnetic actuator and are not limited to the specific structure shown in the figures.

Although possible embodiments have been described illustratively in the above description, it should be understood that there are still a large number of embodiment variations through combinations of all known technical features and implementations as well as those are readily apparent to those skilled in the art. In addition, it should be further understood that the exemplary implementations are just examples and shall not in any way limit the scope of protection, application and construction of the present disclosure. The foregoing description is more intended to provide those skilled in the art with a technical guide for converting at least one exemplary implementation, in which various changes, especially changes in the functions and structures of the components, can be made as long as they do not depart from the scope of protection of the claims.

LIST OF REFERENCE NUMERALS