Electric actuator

Abstract

The utility model provides an electric actuator. The electric actuator comprises a lead screw assembly, a motor assembly, a bearing assembly and a guide assembly. The rotary motion of a nut in the lead screw assembly drives a roller to do compound motion of planetary motion and spiral motion, and then a lead screw is driven to do linear motion, so that the actual lead of the whole lead screw nut transmission pair is far smaller than the physical lead of the nut, and equivalently, an intangible speed reducing mechanism is installed between a motor and a lead screw nut mechanism; and a speed reducer does not exist in the physical structure. The electric actuator is driven by the motor, the small-lead rolling friction spiral transmission mechanism serves as a main body, a nut of the spiral transmission mechanism serves as a rotor structure part for driving the motor, rotary motion input into the motor is converted into linear motion to be output, and an overall mechanical and electrical integrated structure is formed.

Description

Technical Field

[0001] The present application relates to mechanical transmission technology, and in particular to a mechatronic electric actuator. Background Art

[0002] Electromechanical actuators are usually a kind of working device that converts the rotary motion of the motor into linear motion. They are widely used in the engineering field. The general electromechanical actuator adopts the combination of motor, reducer and screw assembly. This mode has the disadvantages of large size and complex structure. This disadvantage is particularly prominent in the occasions that require small size, light weight and large output load. Utility Model Content

[0003] In view of the above problems, the present application aims to provide an electric actuator.

[0004] The electric actuator of the present application comprises: a lead screw assembly, a motor assembly, a bearing assembly, and a guide assembly;

[0005] The screw assembly comprises: a screw body, a nut, and a plurality of rollers; the screw assembly is used to convert the input rotational motion into linear motion; the screw body is installed at the center of the nut; the plurality of rollers are evenly distributed between the screw body and the nut along the outer circumference of the screw body; one of the screw body and the nut serves as a rotation input element, and the other serves as a linear motion output element;

[0006] The motor assembly includes a motor housing and a rotor;

[0007] The bearing assembly is fixed to the motor housing and is located at the first end of the lead screw assembly, and is used to provide support for the linear motion of the lead screw assembly;

[0008] The guide assembly is mounted on the motor housing and is located at the second end of the screw assembly, and is used to guide the linear motion output element of the screw assembly to perform linear motion;

[0009] The lead screw assembly is installed in the central hole of the rotor of the motor assembly; the rotor of the motor assembly and the rotating input element of the lead screw assembly are fixedly connected together or formed in one piece;

[0010] When the rotor of the motor assembly rotates, the rotor drives the rotating input element of the screw assembly to rotate, and the input element drives multiple rollers to rotate while revolving around the screw body. The screw body, nut, and multiple rollers of the screw assembly form a compound motion of planetary motion and spiral motion. The linear motion output element of the screw assembly outputs linear motion with a predetermined stroke to the outside, thereby converting the rotational motion of the motor assembly into linear motion output.

[0011] Preferably, in the screw assembly,

[0012] Each roller is formed into a stepped rotating body, including: a first cylindrical section, a first gear, a first small diameter section, and a first large diameter section; the first cylindrical sections are respectively formed at both ends of the roller; the first gears are respectively formed at both ends of the roller and are located on one end of the first cylindrical section facing the center of the roller; the first small diameter section and the first large diameter section are located between the first gears at both ends of the roller and are arranged alternately; a plurality of equally spaced annular grooves are respectively formed on the outer circumferences of the first small diameter section and the first large diameter section;

[0013] The lead screw body is also formed as a stepped rotating body, which includes: a second cylindrical section, a second gear, a second small diameter section, and a second large diameter section; the second cylindrical sections are respectively formed at both ends of the lead screw body; the second gears are respectively formed at both ends of the lead screw body and are located on one end of the second cylindrical section facing the center of the lead screw body; the second small diameter section and the second large diameter section are alternately arranged between the second gears at both ends of the lead screw body; a plurality of equally spaced annular grooves are formed on the outer circumferential surface of the second large diameter section;

[0014] An internal thread is formed on the inner circumferential surface of the nut;

[0015] The internal thread of the nut is meshed with the multiple annular grooves of the first large diameter section of the multiple rollers, and the pitch of the internal thread of the nut is equal to the groove pitch between the multiple annular grooves of the first large diameter section of the rollers; the multiple annular grooves of the first small diameter section of the multiple rollers are meshed with the multiple annular grooves of the second large diameter section of the screw body, and the groove pitch between the multiple annular grooves of the first small diameter section of the rollers is equal to the groove pitch between the multiple annular grooves of the second large diameter section of the screw body; the second small diameter section of the screw body does not interfere with the first large diameter section of the multiple rollers; the first gears at both ends of the multiple rollers are meshed with the second gears at both ends of the screw body; the pitch circle diameter of the first gear of the roller is equal to the middle diameter of the teeth of the first gear of the roller, and the pitch circle diameter of the second gear of the screw body is equal to the middle diameter of the teeth of the second gear of the screw body.

[0016] Preferably, in the screw assembly,

[0017] The screw body is a cylindrical rotating body with external threads;

[0018] The nut is a rotating body with a stepped inner hole; internal gears are arranged at both ends of the nut; a third large diameter section and a third small diameter section are alternately formed between the internal gears at both ends of the nut; a plurality of equally spaced annular grooves are formed on the inner circumference of the third small diameter section;

[0019] Each roller is formed into a stepped rotating body, including: a first cylindrical section, a first gear, a first small diameter section, and a first large diameter section; the first cylindrical sections are respectively formed at both ends of the roller; the first gears are respectively formed at both ends of the roller and are located on one end of the first cylindrical section facing the center of the roller; the first small diameter section and the first large diameter section are located between the first gears at both ends of the roller and are arranged alternately; a plurality of equally spaced annular grooves are respectively formed on the outer circumferences of the first small diameter section and the first large diameter section;

[0020] The first gear of the roller is meshed with the corresponding internal gear of the nut; the annular groove of the first small diameter section of the roller is meshed with the annular groove of the third small diameter section of the nut correspondingly; the multiple annular grooves of the first large diameter section of the roller are meshed with the external thread of the screw body, and the groove pitch between the multiple annular grooves of the first large diameter section of the roller is equal to the pitch of the external thread of the screw body; the third large diameter section of the nut does not interfere with the first large diameter section of the roller.

[0021] Preferably, the nut of the screw assembly serves as a rotation input element, and the screw body serves as a linear motion output element.

[0022] Preferably, the screw body of the screw assembly serves as a rotation input element, and the nut serves as a linear motion output element.

[0023] Preferably, the first cylindrical sections at both ends of the plurality of rollers are respectively combined with indexing rings.

[0024] Preferably, the first gear is integrally formed on the roller corresponding thereto.

[0025] Preferably, the first gear is detachably fixed to the roller corresponding thereto.

[0026] Preferably, the second gear is integrally formed on the screw body.

[0027] Preferably, the second gear is detachably fixed to the screw body.

[0028] The electric actuator of the present application does not require a reducer, and organically integrates the motor structure with a special lead screw transmission pair as an actuator to form a whole, thereby achieving the purpose of reducing volume and weight and increasing output load capacity. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1a , 1b , 1c, 1d are structural diagrams of a first embodiment of the electric actuator of the present application;

[0030] Figure 2 A structural diagram of a first embodiment of the electric actuator of the present application;

[0031] Figure 3An exploded view of a first embodiment of the electric actuator of the present application;

[0032] Figure 4 is a schematic cross-sectional structure diagram of a second embodiment of the electric actuator of the present application;

[0033] Figure 5 A nut configuration of a second embodiment of the electric actuator of the present application;

[0034] Figure 6a , 6b A schematic structural diagram of another embodiment of the lead screw assembly of the first embodiment of the electric actuator of the present application. DETAILED DESCRIPTION

[0035] The first embodiment of the electric actuator of the present application is as follows Figure 1a-1d As shown in , 2 and 3, it includes a screw assembly 1, a motor assembly 2, a bearing assembly 3 and a guide assembly 4.

[0036] Screw assembly 1 Figure 1a-1d As shown in FIG. 2 , with the screw body 13 as the center, a plurality of rollers 12 are arranged along the circumferential direction around the outer diameter of the screw.

[0037] The roller 12 is a rotating body with a cylindrical outer profile, which includes a cylindrical section 120, a gear 121, a small diameter section 122, and a large diameter section 123; the cylindrical section 120 and the gear 121 are formed on each end of the roller 12. At each end of the roller 12, the cylindrical section 120 cooperates with the circumferentially uniformly distributed holes on the dividing ring 14; the small diameter section 122 and the large diameter section 123 can be several sections, and the small diameter section 122 and the large diameter section 123 are arranged alternately. The small diameter section 122 and the large diameter section 123 are provided with a thread with a helical lead angle of 0, that is, an annular groove.

[0038] The screw body 13, similar in appearance to the roller 12, is also a rotating body component with a cylindrical outer profile, and includes a guide cylindrical section 131, a gear 132, a large diameter section 133, and a small diameter section 134. An annular groove is provided in the large diameter section 133. The annular groove of the large diameter section 133 of the screw body 13 is correspondingly meshed with the annular groove of the small diameter section 122 of the roller 12, and the groove pitch and tooth profile of the annular groove of the large diameter section 133 correspond to those of the annular groove of the small diameter section 122. The small diameter section 134 of the screw body 13 avoids interference with the large diameter section 123 of the roller 12. A guide seal 15 is fixedly connected to the second end of the screw body 13. The guide seal 15, the guide cylindrical section 131, and the screw body 13 are coaxial.

[0039] The nut 11 is a member with an internal thread, and its internal thread can be a common single-start spiral with a fixed pitch, or other appropriate spirals. The pitch of its internal thread is the same as the pitch of the annular groove on the large diameter section 123 of the roller 12, and can form a meshing relationship. The outer diameter of the nut 11 and the rotor 22 of the motor assembly 2 are coaxial integral parts or fixed integral components. Usually, the nut screw part passes through the center hole of the motor assembly to reduce the volume and weight.

[0040] The bearing component 3 is as follows Figure 1a-1d 2, it is a disc assembly. The center of the bearing assembly 3 is provided with a hole to form a sliding fit with the guide cylindrical section 131; the end surface of the bearing assembly 3 is provided with a mounting surface to mount the thrust bearing 31. The other end surface of the thrust bearing 31 is in plane contact with one end surface of the rotor 22 of the motor assembly 2. The bearing assembly 3 is fastened to the motor housing 21.

[0041] The guide assembly 4 is used to guide the screw body 13 when it makes axial linear motion, and ensures that the axis of the screw body 13, the axis of the nut 11, and the axis of the motor assembly 2 are coaxial. The guide assembly 4 is fastened to the motor housing 21.

[0042] When the motor assembly 2 is working, the rotor 22 rotates, and the nut 11 rotates. The rotating nut 11 drives the roller 12 to rotate, driving the screw body 13, the guide cylindrical section 131, and the guide seal 15 to perform axial linear motion. At this time, the screw body 13 is anti-rotation. The anti-rotation of the screw body 13 can be achieved externally, or the part 131 can be changed to a non-rotational body shape in cross section.

[0043] The gears 121 at both ends of the roller 12 and the gears 132 at both ends of the screw body 13 are always in meshing state after assembly. During operation, the gears 121 on the roller 12 revolve around the gears 132 on the screw body 13, and the gears 121 on the roller 12 rotate at the same time. In particular, the pitch diameters of the gears 121 at both ends of the roller 12 are equal to the mean diameter of the helical angle-free screw teeth of the small diameter section 122 of the roller 12 and the mean diameter of the helical angle-free screw teeth of the large diameter section 133 of the screw body 13, respectively. The gears 121 are spur gears, and the gears at both ends are in the same phase.

[0044] like Figure 4 The second embodiment of the electric actuator is shown in FIG. 1 . It is characterized in that the lead screw body 13 is a cylindrical rotating body with an external thread, and the nut 11 is a rotating body with a stepped inner hole. Internal gears 135 are formed at both ends of the nut 11; a large diameter section and a small diameter section are formed between the internal gears 135 at both ends; and an annular groove with a pitch of 0 is formed on the inner circumference of the small diameter section. The structure of the roller 12 is similar to that of the roller 12. Figure 1a-1d, 2 have the same structure. Annular grooves with a pitch of 0 are formed on the outer circumference of the large diameter section and the small diameter section of the roller 12. Gears 121 are provided at both ends of the roller 12. The gear 121 on the roller 12 is meshed with the gear 135 on the nut 11 and conforms to the law of planetary motion. The center line is the common axis of the nut 11 and the screw body 13. The external thread of the screw body 13 is meshed with the annular groove of the large diameter section of the roller 12, and the pitch is the same. The annular groove of the small diameter section of the roller 12 is meshed with the annular groove of the small diameter section of the nut 11, and the groove pitch is the same. The large diameter section of the nut 11 does not interfere with the large diameter section of the roller 12.

[0045] During operation, the lead screw body 13 is used as an active component to input rotary motion, and the nut 11 outputs linear motion. The first end of the lead screw body 13 is fastened to the rotor 22 of the motor assembly 2. The structural form of the nut 11 is as follows: Figure 5 In particular, the pitch diameter of the gear end 121 of the roller 12 is equal to the mid-diameter of the non-helix thread of the small diameter section 122 of the roller 12 and the mid-diameter of the non-helix thread of the small diameter section 134 of the nut 11. The gear is a spur gear, and the gears at both ends are in the same phase.

[0046] The electric actuator of the present application may also have other implementations.

[0047] The third implementation method is Figure 1a-1d Modifications are made based on the illustrated embodiments. Figure 1a-1d The structure of the screw-nut pair remains unchanged, but the screw body is used as the active input component, that is, the rotor of the motor assembly 2 is fixedly connected to the screw body. Figure 4 The connection method shown in is similar to that shown in . Correspondingly, the output piece is changed to a nut.

[0048] The fourth implementation method is Figure 4 Modifications based on the embodiment shown Figure 4 The structure of the screw nut pair in the embodiment remains unchanged, but the nut is used as the active input member, that is, the rotor of the motor assembly 2 is fixedly connected to the nut, and the connection form can be as follows: Figure 1a-1d The connection method between the nut and the rotor described in the above is changed. Correspondingly, the screw body is changed into an output member.

[0049] The electric actuator of the present application is driven by an electric motor and takes a small-lead rolling friction screw transmission mechanism (i.e., a screw assembly) as the main body. The nut or the screw body of the screw assembly is fixed together or integrally constructed with the rotor of the electric motor, converting the rotational motion of the input motor into a linear motion output, forming an overall mechatronic structure.

[0050] The notable feature of the screw assembly is that its components are composed of a nut, a roller and a screw body. The three form a planetary motion in the cross section. That is, the outer circle of the screw body section is equivalent to the sun gear, and the outer circle of the roller section is equivalent to the planetary gear. The planetary gear can rotate and revolve around the sun, and its outer edge movement is constrained by the nut. These movements conform to the laws of planetary motion. While performing spatial rotational motion, they also perform axial motion. For this purpose, spiral grooves are provided on the three basic components.

[0051] by Figure 1a-1d Taking the first embodiment shown as an example, the thread of the nut is a single-start helix with a fixed pitch, and the roller is a stepped, segmented, equal-diameter rotating body with an annular groove. The pitch and tooth shape of the large-diameter section can mesh with the nut, and the pitch and tooth shape of the small-diameter section can mesh with the lead screw. The lead screw corresponds to the roller, and is also a stepped, segmented, equal-diameter rotating body. The large-diameter section has an annular groove that meshes with the roller. The small-diameter section is a smooth rotating body, and the principle is not to interfere with the large-diameter section of the roller. In order to ensure planetary motion, gears are set at both ends of the roller, which form a meshing relationship with the gears set at both ends of the lead screw. A dividing ring is installed at the end of the roller. The roller can rotate freely in the hole of the dividing ring.

[0052] The motor in the present application can be a specially designed motor structure, wherein the rotor and the nut are integrally structured, or the nut and the rotor are fastened together and the two are coaxial. To reduce the volume, the rotor is usually located at the outer edge of the nut. When the lead screw is restricted from rotating, the rotary motion of the motor will be converted into a linear motion output of the lead screw through the lead screw nut mechanism.

[0053] In order to ensure the output direction of the lead screw, the left and right ends are respectively restricted by guide rotating bodies to allow only linear motion, and the center line of the rotating body coincides with the axis of the motor rotor.

[0054] In order to bear the axial load during operation, thrust bearings and bearing structures that can be independently installed and adjusted are provided. Since the equivalent lead is much smaller than the physical lead of the nut, the working device is kinematically self-locking.

[0055] For the convenience of manufacturing and assembly, the entire actuator is divided into three modules, namely the screw module, the motor module, and the bearing module. In this way, the three modules can be manufactured independently and then assembled and debugged centrally.

[0056] For efficiency and cost considerations, the lead screw and roller of the lead screw assembly are both external cylindrical rotating bodies, and the grooves of their working tooth profiles are shallow, which can be precisely manufactured at high speed by rolling, a chipless processing method; similarly, the nut can also be processed by rolling. This allows the manufacture of low-cost core components of the actuator.

[0057] Beneficial Effects

[0058] 1. The electric actuator of the present application is driven by an electric motor and uses a rolling friction screw transmission mechanism with a small lead as the main transmission body. The additional speed reduction mechanism is eliminated, but the torque can be increased, thereby converting the input rotary motion into a linear motion output with the simplest structure.

[0059] 2. The rolling friction spiral transmission mechanism has no slipping phenomenon due to the mutual meshing between gears, accurate transmission ratio, large load-bearing capacity, small wear and high efficiency;

[0060] 3. The mechatronic structure integrates the power motor structure into the interior of the brake and organically integrates it with the transmission mechanism, making the overall structure of the actuator compact, and achieving the effect of small size and light weight.

[0061] 4. It can be self-locking, without the need for external mechanisms.

[0062] 5. The core components of the spiral transmission mechanism can make full use of the chipless processing method to achieve efficient, low-cost and environmentally friendly processing and manufacturing.

Claims

1. An electric actuator, comprising: Screw assembly, motor assembly, bearing assembly, guide assembly; The screw assembly comprises: a screw body, a nut, and a plurality of rollers; the screw assembly is used to convert the input rotational motion into linear motion; the screw body is installed at the center of the nut; the plurality of rollers are evenly distributed between the screw body and the nut along the outer circumference of the screw body; one of the screw body and the nut serves as a rotation input element, and the other serves as a linear motion output element; The motor assembly includes a motor housing and a rotor; The bearing assembly is fixed to the motor housing and is located at the first end of the lead screw assembly, and is used to provide support for the linear motion of the lead screw assembly; The guide assembly is mounted on the motor housing and is located at the second end of the screw assembly, and is used to guide the linear motion output element of the screw assembly to perform linear motion; The lead screw assembly is installed in the central hole of the rotor of the motor assembly; the rotor of the motor assembly and the rotating input element of the lead screw assembly are fixedly connected together or formed in one piece; When the rotor of the motor assembly rotates, the rotor drives the rotating input element of the screw assembly to rotate, and the input element drives multiple rollers to rotate while revolving around the screw body. The screw body, nut, and multiple rollers of the screw assembly form a compound motion of planetary motion and spiral motion. The linear motion output element of the screw assembly outputs linear motion with a predetermined stroke to the outside, thereby converting the rotational motion of the motor assembly into linear motion output.

2. The electric actuator according to claim 1, characterized in that: In the screw assembly, Each roller is formed into a stepped rotating body, including: a first cylindrical section, a first gear, a first small diameter section, and a first large diameter section; the first cylindrical sections are respectively formed at both ends of the roller; the first gears are respectively formed at both ends of the roller and are located on one end of the first cylindrical section facing the center of the roller; the first small diameter section and the first large diameter section are located between the first gears at both ends of the roller and are arranged alternately; a plurality of equally spaced annular grooves are respectively formed on the outer circumferences of the first small diameter section and the first large diameter section; The lead screw body is also formed as a stepped rotating body, which includes: a second cylindrical section, a second gear, a second small diameter section, and a second large diameter section; the second cylindrical sections are respectively formed at both ends of the lead screw body; the second gears are respectively formed at both ends of the lead screw body and are located on one end of the second cylindrical section facing the center of the lead screw body; the second small diameter section and the second large diameter section are alternately arranged between the second gears at both ends of the lead screw body; a plurality of equally spaced annular grooves are formed on the outer circumferential surface of the second large diameter section; An internal thread is formed on the inner circumferential surface of the nut; The internal thread of the nut is meshed with the multiple annular grooves of the first large diameter section of the multiple rollers, and the pitch of the internal thread of the nut is equal to the groove pitch between the multiple annular grooves of the first large diameter section of the rollers; the multiple annular grooves of the first small diameter section of the multiple rollers are meshed with the multiple annular grooves of the second large diameter section of the screw body, and the groove pitch between the multiple annular grooves of the first small diameter section of the rollers is equal to the groove pitch between the multiple annular grooves of the second large diameter section of the screw body; the second small diameter section of the screw body does not interfere with the first large diameter section of the multiple rollers; the first gears at both ends of the multiple rollers are meshed with the second gears at both ends of the screw body; the pitch circle diameter of the first gear of the roller is equal to the middle diameter of the teeth of the first gear of the roller, and the pitch circle diameter of the second gear of the screw body is equal to the middle diameter of the teeth of the second gear of the screw body.

3. The electric actuator according to claim 1, characterized in that: In the screw assembly, The screw body is a cylindrical rotating body with external threads; The nut is a rotating body with a stepped inner hole; internal gears are arranged at both ends of the nut; a third large diameter section and a third small diameter section are alternately formed between the internal gears at both ends of the nut; a plurality of equally spaced annular grooves are formed on the inner circumference of the third small diameter section; Each roller is formed into a stepped rotating body, including: a first cylindrical section, a first gear, a first small diameter section, and a first large diameter section; the first cylindrical sections are respectively formed at both ends of the roller; the first gears are respectively formed at both ends of the roller and are located on one end of the first cylindrical section facing the center of the roller; the first small diameter section and the first large diameter section are located between the first gears at both ends of the roller and are arranged alternately; a plurality of equally spaced annular grooves are respectively formed on the outer circumferences of the first small diameter section and the first large diameter section; The first gear of the roller is meshed with the corresponding internal gear of the nut; the annular groove of the first small diameter section of the roller is meshed with the annular groove of the third small diameter section of the nut correspondingly; the multiple annular grooves of the first large diameter section of the roller are meshed with the external thread of the screw body, and the groove pitch between the multiple annular grooves of the first large diameter section of the roller is equal to the pitch of the external thread of the screw body; the third large diameter section of the nut does not interfere with the first large diameter section of the roller.

4. The electric actuator according to any one of claims 2 to 3, characterized in that: The nut of the screw assembly serves as a rotation input element, and the screw body serves as a linear motion output element.

5. The electric actuator according to any one of claims 2 to 3, characterized in that: The screw body of the screw assembly serves as a rotation input element, and the nut serves as a linear motion output element.

6. The electric actuator according to any one of claims 2 to 3, characterized in that: The first cylindrical sections at both ends of the plurality of rollers are respectively combined with indexing rings.

7. The electric actuator according to any one of claims 2 to 3, characterized in that: The first gear is integrally formed on the roller corresponding thereto.

8. The electric actuator according to any one of claims 2 to 3, characterized in that: The first gear is detachably fixed to the roller corresponding thereto.

9. The electric actuator according to claim 2, characterized in that: The second gear is integrally formed on the lead screw body.

10. The electric actuator according to claim 2, characterized in that: The second gear is detachably fixed to the lead screw body.

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