JP2016070324A - Electric actuator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electric actuator in which peripheral components of a ball screw mechanism is formed as a unit, which has good work efficiency and which has improved productivity by assembling a sub-assembly in which the ball screw assembly is assembled in one housing and the other housing formed as a unit.SOLUTION: An electric actuator includes: a second housing sub-assembly A in which a through-hole 11 and a bag hole 12 for accommodating a screw shaft 10 in a first housing 2a and a second housing 2b are formed, in which, at the second housing 2b including the bag hole 12, a ball screw assembly is mounted in which a ball screw mechanism 8, a pair of support bearings 20 and an output gear 6 are formed as a unit, and in which a sleeve 17 is fitted and inserted in which the screw shaft 10 is supported so that it cannot rotate and it cannot move in an axial direction; and a first housing sub-assembly B in which an electric motor 3 is mounted on the first housing 2a including the through-hole 11. Two housing sub-assemblies A, B are fastened by a fixing bolt 35.SELECTED DRAWING: Figure 5

Description

  The present invention relates to an electric actuator provided with a ball screw mechanism used in a drive unit of a general industrial electric motor, automobile, and the like. Specifically, a rotational input from an electric motor is linearly moved through a ball screw mechanism. The present invention relates to an electric actuator that converts into

  In electric actuators used in various drive units, a gear mechanism such as a trapezoidal screw or a rack and pinion is generally used as a mechanism for converting the rotational motion of the electric motor into a linear motion in the axial direction. Since these conversion mechanisms involve a sliding contact portion, the power loss is large, and it is necessary to increase the size of the electric motor and increase the power consumption. Therefore, a ball screw mechanism has been adopted as a more efficient actuator.

  The structure of the electric actuator employing the ball screw mechanism will be described with reference to the structure of FIG. 1 used in the description of the embodiment of the present invention. The electric actuator 1 includes a cylindrical housing 2, an electric motor 3 attached to the housing 2, an intermediate gear 5 that meshes with an input gear 4 attached to a motor shaft 3 a of the electric motor 3, and the intermediate gear 5. A reduction mechanism 7 comprising an output gear 6 meshing with the gear 5 and a ball screw mechanism 8 for converting the rotational movement of the electric motor 3 into the linear movement in the axial direction of the drive shaft 9 via the reduction mechanism 7 are provided. .

  The housing 2 is formed of an aluminum alloy such as A6063TE or ADC12 by aluminum die casting, and includes a first housing 2a and a second housing 2b abutted on the end face, and is integrally formed by a fixing bolt (not shown). It is fixed. An electric motor 3 is attached to the first housing 2a, and a through hole 11 and a bag hole 12 for accommodating the screw shaft 10 are formed in each of the first housing 2a and the second housing 2b. Yes.

  The motor shaft 3a of the electric motor 3 is rotatably supported by a rolling bearing 13 composed of a deep groove ball bearing mounted on the second housing 2b. It is supported freely. An output gear 6 that meshes with an intermediate gear 5 that is a spur gear is integrally fixed to a nut 18 that constitutes a ball screw mechanism 8 described later via a key 14.

  The drive shaft 9 is configured integrally with a screw shaft 10 constituting the ball screw mechanism 8, and locking pins 15 and 15 are implanted at one end portion (right end portion in the figure) of the drive shaft 9. A sleeve 17 is fitted into the bag hole 12 of the second housing 2b, and concave grooves 17a and 17a extending in the axial direction are formed on the inner periphery of the sleeve 17 by grinding. The concave grooves 17a and 17a are arranged opposite to each other in the circumferential direction, and the locking pins 15 and 15 of the screw shaft 10 are engaged with the concave grooves 17a and 17a, respectively, so that the screw shaft 10 cannot rotate. And is supported so as to be movable in the axial direction. The sleeve 17 is prevented from coming off in the axial direction by a retaining ring 16 for a hole attached to the opening of the bag hole 12 of the second housing 2b.

  Note that the sleeve 17 is not in direct contact with the bottom of the second housing 2 b and is fixed via a cap 36. That is, the cap 36 is externally fitted to the end of the sleeve 17 and is integrally fitted to the bottom of the second housing 2b. As a result, the screw shaft 10 does not directly collide with the bag hole 12 of the second housing 2b, thereby reducing damage and wear of the second housing 2b, reducing weight, and improving durability and strength. It is possible to improve the reliability.

  Here, the sleeve 17 is made of a sintered alloy prepared by adjusting a metal powder into a plastic shape and molding it with an injection molding machine. In this injection molding, first, metal powder and a binder made of plastic and wax are kneaded by a kneader, and the kneaded product is granulated into pellets. The granulated pellets are molded by so-called MIM (Metal Injection Molding), which is supplied to a hopper of an injection molding machine and pushed into a mold in a heated and melted state. A sintered alloy formed by such an MIM can be easily and accurately formed into a desired shape / dimension even if it has a high workability and a complicated shape.

  On the other hand, the locking pin 15 that engages with the concave groove 17a is formed of high carbon chromium bearing steel such as SUJ2 or carburized bearing steel such as SCr435, and has a carbon content of 0.80% by weight or more and 58HRC on its surface. The carbonitriding layer described above is formed. In addition, by applying the needle roller used for the needle roller bearing to the locking pin 15, a surface hardness of 58HRC or more can be obtained, the wear resistance is excellent, the availability is good, and the cost is low. Can be achieved.

  As shown in an enlarged view in FIG. 2, the ball screw mechanism 8 includes a screw shaft 10 and a nut 18 that is externally inserted to the screw shaft 10 via a ball 19. The screw shaft 10 has a spiral thread groove 10a formed on the outer periphery. On the other hand, the nut 18 is formed with a helical thread groove 18a corresponding to the thread groove 10a of the screw shaft 10 on the inner periphery, and a large number of balls 19 are accommodated between these thread grooves 10a and 18a so as to be able to roll. ing. The nut 18 is supported on the housings 2a and 2b via a pair of support bearings 20 and 20 so as to be rotatable and not movable in the axial direction. Reference numeral 21 denotes a piece member that constitutes a circulation member by connecting the thread grooves 18a of the nut 18, and the piece member 21 allows an infinite circulation of a large number of balls 19.

  The cross-sectional shape of each of the thread grooves 10a and 18a may be a circular arc shape or a gothic arc shape, but here, a gothic arc shape that allows a large contact angle with the ball 19 and a small axial clearance can be set. Is formed. Thereby, the rigidity with respect to an axial load becomes high and generation | occurrence | production of a vibration can be suppressed.

  The nut 18 is made of case-hardened steel such as SCM415 or SCM420, and its surface is subjected to hardening treatment in a range of 55 to 62 HRC by vacuum carburizing and quenching. Thereby, the buffing etc. for the scale removal after the heat treatment can be omitted, and the cost can be reduced. On the other hand, the screw shaft 10 is made of medium carbon steel such as S55C or case-hardened steel such as SCM415 or SCM420, and its surface is hardened in the range of 55 to 62 HRC by induction hardening or carburizing hardening.

  An output gear 6 constituting the speed reduction mechanism 7 is fixed to the outer peripheral surface 18b of the nut 18 via a key 14, and two support bearings 20 and 20 are press-fitted on both sides of the output gear 6 via a predetermined squeeze. Has been. Specifically, a key groove 14a is formed on the outer peripheral surface 18b of the nut 18, and a key groove 6c is also formed in a circular hole 6b of the output gear 6 described later, and a rectangular shape formed by both the key grooves 14a, 6c. The key 14 is inserted into the shape space, and the output gear 6 is fixed to the nut 18. As a result, even when a thrust load is applied from the drive shaft 9, it is possible to prevent the axial displacement between the support bearings 20, 20 and the output gear 6. Further, the two support bearings 20 and 20 are constituted by sealed deep groove ball bearings having shield plates 20a and 20a attached to both ends, and leakage of the lubricating grease enclosed in the bearings to the outside and from the outside This prevents wear powder from entering the bearing.

  In addition, one (left side in the figure) of the pair of support bearings 20 and 20 is attached to the first housing 2a via a washer 22 made of a ring-shaped elastic member. The washer 22 is formed by press working from an austenitic stainless steel sheet (JIS standard SUS304 system or the like) having high strength and wear resistance or a rust-proof cold rolled steel sheet (JIS standard SPCC system or the like). It consists of a wave washer. The inner diameter D is formed larger than the outer diameter d of the inner ring 23 of the support bearing 20. As a result, the axial backlash of the pair of support bearings 20 and 20 can be eliminated, smooth rotation performance can be obtained, and the washer 22 abuts only on the outer ring 24 of the support bearing 20 to become a rotating ring. Since there is no interference with the inner ring 23, even if a reverse thrust load is generated and the nut 18 is pressed against the first housing 2a, the inner ring 23 of the support bearing 20 contacts the first housing 2a and the frictional force increases. Can be reliably prevented from entering the locked state.

  As shown in FIG. 1, the gear shaft 25 of the intermediate gear 5 constituting the speed reduction mechanism 7 is implanted in the first and second housings 2 a and 2 b, and the intermediate gear 5 is connected to this gear via a rolling bearing 26. The shaft 25 is rotatably supported. Of the end portions of the gear shaft 25, for example, when the end portion on the first housing 2 a side is press-fitted, the end portion on the second housing 2 b side is set to a clearance fit, thereby making misalignment (assembly error). Allowing smooth rotation performance can be ensured. The rolling bearing 26 includes a so-called steel plate outer ring 27 that is press-fitted into the inner diameter of the intermediate gear 5, and a plurality of needle rollers 29 that are rotatably accommodated in the outer ring 27 via a cage 28. It consists of a shell-type needle roller bearing. Thereby, the availability of a bearing is high and cost reduction can be achieved.

  Further, ring-shaped washers 30 and 30 are mounted on both sides of the intermediate gear 5 to prevent the intermediate gear 5 from directly contacting the first and second housings 2a and 2b. Here, the width of the tooth portion 5a of the intermediate gear 5 is formed smaller than the tooth width. As a result, the contact area between the intermediate gear 5 and the washer 30 can be reduced, and a smooth rotational performance can be obtained while suppressing frictional resistance during rotation. Here, the washer 30 is a flat washer formed by press working from an austenitic stainless steel plate having high strength and high wear resistance, or a cold-rolled steel plate treated with rust. In addition to this, for example, it is formed of a thermoplastic synthetic resin such as PA (polyamide) 66 filled with a predetermined amount of a fibrous reinforcing material such as brass, sintered metal, or GF (glass fiber). May be.

  The output gear 6 is made of a sintered alloy, and as shown in FIG. 2, a tooth portion 6a made of spur teeth is formed on the outer periphery, and a circular hole 6b fitted to the outer peripheral surface 18b of the nut 18 is formed. Yes. A plurality of circular hollow holes 33 are formed at equal intervals in the central portion 34 between the outer diameter portion 31 in the vicinity of the tooth portion 6a and the boss portion 32 in the vicinity of the circular hole 6b. In addition, a key groove 6c into which the above-described fixing key 14 is inserted is formed on the inner periphery of the cylindrical circular hole 6b.

  In the conventional assembly of such an electric actuator 1, components are sequentially mounted inside one of the first and second housings 2a and 2b, and after mounting all the components, the other housing is mounted. The assembly is completed by attaching and fastening with fixing bolts. Specifically, a conventional assembly method will be described with reference to FIGS.

  First, as shown in FIG. 7, a rolling bearing 13 for supporting an input gear (not shown) is mounted on the second housing 2b, and a gear shaft 25 for supporting an intermediate gear (not shown) is press-fitted. The Thereafter, as shown in FIG. 8A, the cap 36 and the sleeve 17 are fitted into the bottom of the bag hole 12 of the second housing 2b, and the retaining ring 16 for retaining the sleeve 17 is attached. And as shown to (b), one support bearing 20 is press-fit in the 2nd housing 2b among a pair of support bearings 20 which support a nut (not shown).

  Next, as shown in FIG. 9A, the locking pin 15 is press-fitted into the end of the screw shaft 10, and as shown in FIG. Thus, the output gear 6 is fixed to the nut 18. On the other hand, a large number of balls 19 are arranged on the nut 18, and the screw shaft 10 is inserted thereinto, and the ball screw mechanism 8 is assembled as shown in FIG.

  As shown in FIG. 10, the ball screw mechanism 8 is mounted on the second housing 2b, and the intermediate gear unit G, ie, the intermediate gear 5 and a roller needle roller bearing are mounted on the gear shaft 25. The bearing 26 and washers 30 and 30 are mounted.

  On the other hand, as shown in FIG. 11, one of the pair of support bearings 20 that support a nut (not shown) is mounted on the first housing 2a. Then, as shown in FIG. 12, the first housing 2 a and the second housing 2 b are combined and fastened by a fixing bolt 35. And the electric motor 3 shown in FIG. 1 is attached to the 1st housing 2a with the fixing volt | bolt which is not illustrated (for example, refer patent document 1).

JP 2013-148108 A

  In the conventional assembling method shown in FIGS. 7 to 12 described above, each part is assembled to one of the first and second housings 2a and 2b, that is, the second housing 2b. Since the work process being performed is complicated and takes time, there is a problem in that work efficiency is poor and productivity is lowered. Also, in terms of inventory management, it is necessary to manage each part individually, which is complicated.

  The present invention has been made in view of such problems of the prior art. Focusing on unitizing the subassembly for each assembly process, the peripheral parts of the ball screw mechanism are unitized, and the subassembly and By assembling one of the unitized housings and assembling the two housing subassemblies, the work efficiency can be improved and the productivity can be improved, and the two housing subassemblies can be assembled on separate lines. An object of the present invention is to provide an electric actuator that can simplify the assembly work and can improve the efficiency of the assembly work because the inventory can be managed.

  In order to achieve such an object, the invention according to claim 1 of the present invention includes a housing, an electric motor attached to the housing, and a speed reduction mechanism that transmits the rotational force of the electric motor via a motor shaft. And a ball screw mechanism that converts the rotational motion of the electric motor into a linear motion in the axial direction of the drive shaft via the reduction mechanism, and the ball screw mechanism is a pair of support bearings mounted on the housing. A nut that is supported so as to be rotatable and not movable in the axial direction, an output gear constituting the speed reduction mechanism is fixed to the outer periphery, and a spiral thread groove is formed on the inner periphery, and a number of It is inserted through a ball, is coaxially integrated with the drive shaft, and has a helical thread groove corresponding to the thread groove of the nut on the outer periphery so that it cannot rotate with respect to the housing. Transfer In the electric actuator constituted by a screw shaft that is supported, the housing includes a first housing and a second housing that abuts on an end surface of the first housing, and the first housing and the second housing. A through-hole and a bag hole for accommodating the screw shaft are formed in each of them, and the ball screw mechanism, the pair of support bearings, and the output gear are unitized in the housing having the bag hole in the housing. One of the housing subassemblies in which a sleeve for supporting the ball screw subassembly is mounted and the screw shaft is supported so as to be non-rotatable and axially movable, and the through hole of the housing The other housing sub-assembly with the electric motor mounted thereon, and the two housing subs Assembly is fastened by a plurality of fixing bolts.

  As described above, the housing, the electric motor attached to the housing, the reduction mechanism that transmits the rotational force of the electric motor through the motor shaft, and the rotational axis of the electric motor through the reduction mechanism are driven. A ball screw mechanism that converts the linear screw motion into an axial linear motion, and the ball screw mechanism is supported by a pair of support bearings mounted on the housing so as to be rotatable and non-movable in the axial direction. The output gear that constitutes the speed reduction mechanism is fixed, and a nut with a spiral thread groove formed on the inner periphery, and this nut is inserted through a large number of balls and integrated coaxially with the drive shaft. In the electric actuator constituted by a screw shaft that is formed with a spiral screw groove corresponding to the screw groove of the nut and is supported so as not to rotate with respect to the housing and to be movable in the axial direction. The winging comprises a first housing and a second housing that abuts on the end face thereof, and each of the first housing and the second housing has a through hole and a bag hole for accommodating the screw shaft. A ball screw sub-assembly in which the ball screw mechanism, a pair of support bearings, and the output gear are unitized is mounted on the housing having the bag hole in the housing, and the screw shaft is not rotatable. And a housing subassembly in which a sleeve for axially movable support is fitted, and the other housing subassembly in which the electric motor is mounted on the housing having the through hole in the housing. The two housing subassemblies are fastened by a plurality of fixing bolts, so that the work efficiency is improved. In addition, the productivity can be improved and the two housing subassemblies can be assembled on separate lines, and inventory management can be performed for each. Therefore, the assembly work can be simplified and the assembly work can be made more efficient. An actuator can be provided.

  Preferably, as described in claim 2, the speed reduction mechanism includes an input gear attached to a motor shaft of the electric motor, an intermediate gear meshing with the input gear, and an output gear meshing with the intermediate gear. If the gear shaft that supports the intermediate gear is fixed to the housing provided with the bag hole, the two housings can be aligned in the latter process with this gear shaft, and no alignment adjustment is required. As a result, the assembly work can be simplified.

  If the rolling bearing for rotatably supporting the input gear attached to the motor shaft of the electric motor is attached to the housing provided with the bag hole as in the invention described in claim 3, a post-process The positioning of the motor shaft becomes easy, and the meshing accuracy of the input gear can be improved.

  Further, as in the invention described in claim 4, if the pair of support bearings are attached to the housing via a radial clearance, assembly work is facilitated and the two housings are aligned. Even when a misalignment occurs in which the surface is displaced in the radial direction, there is no possibility that the internal clearance of the support bearing will be lost.

  An electric actuator according to the present invention includes a housing, an electric motor attached to the housing, a reduction mechanism that transmits the rotational force of the electric motor via a motor shaft, and the electric motor via the reduction mechanism. A ball screw mechanism that converts a rotational motion into a linear motion in the axial direction of the drive shaft. The ball screw mechanism is rotatable via a pair of support bearings mounted on the housing and cannot move in the axial direction. The output gear constituting the speed reduction mechanism is fixed to the outer periphery, a nut having a spiral thread groove formed on the inner periphery, and the nut is inserted into the nut via a large number of balls. A screw shaft that is coaxially integrated and has a spiral screw groove corresponding to the screw groove of the nut formed on the outer periphery thereof, and is supported so as to be non-rotatable and axially movable with respect to the housing. In the electric actuator constituted by the above, the housing is composed of a first housing and a second housing abutted on an end surface thereof, and the screw shaft is provided in each of the first housing and the second housing. A through-hole and a bag hole for receiving are formed, and a ball screw sub-assembly in which the ball screw mechanism, a pair of support bearings, and the output gear are unitized is mounted on the housing provided with the bag hole. And the electric motor is mounted on a housing subassembly in which a sleeve for supporting the screw shaft to be non-rotatable and axially movable is fitted, and a housing having the through hole in the housing. Is mounted on the other housing sub-assembly, and the two housing sub-assemblies are connected to a plurality of fixed sub-assemblies. Since it is fastened with bolts, work efficiency is improved, productivity can be improved, and two housing subassemblies can be assembled on separate lines, and inventory management can be performed for each. In addition, an electric actuator can be provided in which the efficiency of assembly work is improved.

It is a longitudinal section showing one embodiment of an electric actuator concerning the present invention. It is a longitudinal cross-sectional view which expands and shows the ball screw mechanism of FIG. (A)-(d) is explanatory drawing which shows the assembly method of the electric actuator which concerns on this invention, and shows the process of unitizing the peripheral component of a ball screw mechanism. The assembly process of attaching the first housing and peripheral parts to make a sub-assembly, (a) is the process of mounting the O-ring and the input gear to the electric motor, (b) is the fixing bolt being inserted into the electric motor (C) shows a step of assembling a subassembly in which the electric motor is fixed to the first housing. (A) shows an assembly process in which a sleeve, a retaining ring, a rolling bearing and a gear shaft are attached to the second housing to form a sub-assembly, and (b) shows a ball screw mechanism and an intermediate gear unit in the second housing. FIG. 6 shows a process of assembling a subassembly fixed to the second housing. The electric actuator which bolted the subassembly fixed to the 1st housing and the subassembly fixed to the 2nd housing is assembled. It is explanatory drawing which shows the conventional assembly method, and shows the process of press-fitting a rolling bearing and a gear shaft into one housing. FIG. 6 is an explanatory view showing a conventional assembling method, in which (a) shows a step of attaching a sleeve and a retaining ring to one housing, and (b) shows a step of attaching a support bearing. FIG. 4 is an explanatory view showing a conventional assembling method, wherein (a) shows a process of press-fitting a locking pin into a screw shaft, and (b) arranges balls on a nut and fixes an output gear via a key. (C) shows the assembly process of the ball screw mechanism. FIG. 6 is an explanatory view showing a conventional assembling method, showing a process of mounting a ball screw mechanism and an intermediate gear unit on one housing. The same as above, it is explanatory drawing which shows the conventional assembly method, and shows the process of mounting | wearing one housing with a support bearing. The same as above, it is explanatory drawing which shows the conventional assembly method, and shows the process of uniting two housings and fastening with a fixing bolt.

  A housing, an electric motor attached to the housing, a reduction mechanism that transmits the rotational force of the electric motor via a motor shaft, and the rotational movement of the electric motor via the reduction mechanism in the axial direction of the drive shaft A ball screw mechanism for converting the linear screw motion into a linear motion, and the ball screw mechanism is supported by a pair of support bearings mounted on the housing so as to be rotatable and immovable in the axial direction, and is provided on the outer periphery with the deceleration. The output gear constituting the mechanism is fixed, and a nut having a helical thread groove formed on the inner periphery, and the nut is inserted through a large number of balls, and is integrated coaxially with the drive shaft. An electric actuator comprising a screw shaft that is formed so as to correspond to the screw groove of the nut and is supported so as not to rotate with respect to the housing and to be movable in the axial direction. The housing includes a first housing and a second housing that abuts on an end surface thereof, and each of the first housing and the second housing has a through hole for accommodating the screw shaft. A gear shaft supporting the intermediate gear constituting the speed reduction mechanism is press-fitted into the second housing having the bag hole, and the ball screw mechanism and the pair of support bearings and A second housing subassembly in which a ball screw subassembly in which an output gear is unitized is mounted, and a sleeve for inserting the screw shaft so as to be non-rotatable and axially movable is fitted; A first housing subassembly in which the electric motor is mounted on the first housing having a through-hole, and the two housing subassemblies; There are fastened by a plurality of fixing bolts.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
1 is a longitudinal sectional view showing an embodiment of an electric actuator according to the present invention, FIG. 2 is an enlarged longitudinal sectional view showing a ball screw mechanism of FIG. 1, and FIGS. 3 to 6 are according to the present invention. It is explanatory drawing which shows the assembly method of an electric actuator.

  Since the structure of the electric actuator 1 shown in FIG. 1 is as described above, the description of the structure of the electric actuator 1 is omitted or simplified, and the assembly method, which is a characteristic part of the present invention, will be described below.

  In the present embodiment, subassemblies for each assembly process are unitized, and finally these subassemblies are assembled. Specifically, the peripheral parts of the ball screw mechanism are unitized, the ball screw assembly, the process of making the ball screw assembly a subassembly A in one housing, and the other housing unitized in a separate process. The sub-assembly B and the other housing are finally assembled, and are mainly composed of three steps.

  3A to 3D show an assembly process of a ball screw mechanism 8 and a ball screw assembly that unitizes peripheral components of the ball screw mechanism 8. As shown in (a), a pair of support bearings 20 and 20 for rotatably supporting the nut 18 on a second housing 2b (not shown) on an outer peripheral surface 18b of the nut 18 constituting the ball screw mechanism 8. One of the support bearings 20 is press-fitted, and the output gear 6 is fixed to the outer peripheral surface 18b of the nut 18 via the key 14 as shown in FIG. Thereafter, as shown in (c), the other support bearing 20 of the pair of support bearings 20 and 20 is press-fitted into the outer peripheral surface 18b of the nut 18 to form a unit, and a piece member (not shown) is formed on the nut 18. And a number of balls 19 are arranged in a spiral thread groove 18a formed on the inner periphery. Then, as shown in (d), the screw shaft 10 with the locking pin 15 press-fitted into the end portion is inserted into the nut 18 via the ball 19, and the assembly of the ball screw is assembled. In this manner, the pair of support bearings 20 and 20 can be unitized by press-fitting the outer peripheral surface 18 b of the nut 18. This assembly process is referred to as a first process.

  Here, as shown in (b), one support bearing 20 of the pair of support bearings 20 and 20 is press-fitted so as to come into contact with the flange portion 18c formed on the outer periphery of the nut 18, and (c ), The output gear 6 is fixed while being sandwiched between the flange 18c of the nut 18 and the inner ring 23 of the other support bearing 20.

  Next, FIG. 4 shows an assembling process of the subassembly B of the first housing 2a in which the first housing 2a and peripheral parts are unitized. As shown to (a), the O-ring 37 is attached to the electric motor 3, and the input gear 4 is press-fitted into the motor shaft 3a. Thereafter, as shown in (b), the fixing bolt 38 is inserted into the electric motor 3, and as shown in (c), the fixing bolt 38 is screwed into the first housing 2a, whereby the first housing 2a. Subassembly B is assembled. This assembly process is called a second process.

  FIG. 5A shows an assembling process of the subassembly A of the second housing 2b in which the second housing 2b and peripheral parts are unitized. A gear shaft 25 on which an intermediate gear unit, which will be described later, is mounted on the second housing 2b, and a rolling bearing 13 that supports a motor shaft (not shown) with respect to the second housing 2b are mounted. A cap 36 and a sleeve 17 are sequentially attached to the bag hole 12 of the housing 2b, and a retaining ring 16 for retaining the sleeve 17 is attached to assemble the sub-assembly of the housing. This assembly process is called a third process.

  In this way, if the third step includes the step of mounting the rolling bearing 13 that rotatably supports the input gear attached to the motor shaft (not shown) on the second housing 2b, the motor in the subsequent step is provided. Positioning of the shaft is facilitated, and the meshing accuracy of the input gear can be improved.

  Further, if the third step includes the step of fixing the gear shaft 25 supporting the intermediate gear 5 to the second housing 2b, the cores of the first and second housings 2a and 2b in the subsequent steps are provided. Alignment can be performed with the gear shaft 25, and centering adjustment is not required, so that the assembly work can be simplified.

  Next, as shown in (b), the ball screw subassembly is assembled to the subassembly A of the second housing 2b, and the intermediate gear unit G, that is, the intermediate gear 5 and the shell-type needle are mounted on the gear shaft 25. A rolling bearing 26 and washers 30 and 30 made of a tapered roller bearing are mounted. Then, as shown in FIG. 6, finally, the mating surfaces of the first housing 2a and the second housing 2b on which the washer 22 is mounted in advance are brought into contact with the sub-assembly A of the second housing 2b. The fixing bolt 35 is fastened. This assembly process is called a fourth process.

  Here, the pair of support bearings 20 and 20 are attached to the first and second housings 2a and 2b via radial clearances. As a result, the assembling work is facilitated, and even if a so-called misalignment occurs in which the mating surfaces of the first and second housings 2a and 2b are displaced in the radial direction, the internal clearances of the support bearings 20 and 20 may be lost. There is no.

  In the present embodiment, the subassembly for each assembly process is unitized, the peripheral parts of the ball screw mechanism are unitized, and the ball screw subassembly is assembled, and the peripheral parts of the first housing 2a are unitized. The second step of assembling the first housing subassembly B, the third step of assembling the peripheral parts of the second housing 2b into a unit and assembling the second housing subassembly A, and the first housing subassembly Since the fourth step, which is the final step of assembling B and the second housing subassembly A, is provided, work efficiency is improved, productivity can be improved, and two housing subassemblies, that is, the first step A first housing subassembly in which peripheral parts are assembled in one housing 2a B and the second housing subassembly A, in which peripheral parts are assembled in the second housing 2b, can be assembled on separate lines, and inventory management can be performed for each. Therefore, the assembly work can be simplified and the efficiency of the assembly work can be improved. The illustrated electric actuator 1 can be provided.

  The embodiment of the present invention has been described above, but the present invention is not limited to such an embodiment, and is merely an example, and various modifications can be made without departing from the scope of the present invention. Of course, the scope of the present invention is indicated by the description of the scope of claims, and further, the equivalent meanings described in the scope of claims and all modifications within the scope of the scope of the present invention are included. Including.

  An electric actuator according to the present invention includes a ball screw mechanism that is used in a drive unit of a general industrial electric motor, an automobile, or the like, and that converts rotational input from an electric motor into linear motion of a drive shaft through a gear reduction mechanism. Applicable to electric actuators.

DESCRIPTION OF SYMBOLS 1 Electric actuator 2 Housing 2a 1st housing 2b 2nd housing 3 Electric motor 3a Motor shaft 4 Input gear 5 Intermediate gear 5a Intermediate gear tooth 6 Output gear 6a Output gear tooth 6b Output gear circular hole 6c, 14a Key groove 7 Deceleration mechanism 8 Ball screw mechanism 9 Drive shaft 10 Screw shaft 10a, 18a Screw groove 11 Through hole 12 Bag hole 13, 26 Rolling bearing 14 Key 15 Locking pin 16 Retaining ring 17 Sleeve 17a Concave groove 18 Nut 18b Nut Outer peripheral surface 18c nut flange 19 ball 20 support bearing 20a shield plate 21 piece member 22, 30 washer 23 support bearing inner ring 24 support bearing outer ring 25 intermediate gear gear shaft 27 rolling bearing outer ring 28 rolling bearing retainer 29 Roller bearing needle roller 31 Outer diameter part 32 near tooth part Boss part 33 near circular hole Meat Punching hole 34 Central portion 35, 38 Fixing bolt 36 Cap 37 O-ring A Second housing subassembly B First housing subassembly D Washer inner diameter d Support bearing inner ring outer diameter G Intermediate gear unit

Claims (4)

A housing;
An electric motor attached to the housing;
A speed reduction mechanism for transmitting the rotational force of the electric motor via the motor shaft;
A ball screw mechanism that converts the rotational motion of the electric motor to the linear motion in the axial direction of the drive shaft via the speed reduction mechanism, and
The ball screw mechanism is supported rotatably through a pair of support bearings mounted on the housing and is not movable in the axial direction. The output gear constituting the speed reduction mechanism is fixed to the outer periphery, and the inner periphery is helical. A nut formed with a thread-like groove,
The nut is inserted through a large number of balls, is integrated coaxially with the drive shaft, and a helical thread groove corresponding to the thread groove of the nut is formed on the outer periphery so that it cannot rotate with respect to the housing. And an electric actuator composed of a screw shaft supported so as to be axially movable,
The housing includes a first housing and a second housing that abuts on an end surface thereof, and each of the first housing and the second housing has a through hole and a bag for accommodating the screw shaft. A hole assembly is formed and a ball screw sub-assembly in which the ball screw mechanism, a pair of support bearings and the output gear are unitized is mounted on the housing having the bag hole, and the screw shaft rotates. One housing subassembly in which a sleeve for being supported in an axially movable manner is inserted;
An electric actuator comprising: a housing having the through hole in the housing and the other housing subassembly to which the electric motor is mounted, wherein the two housing subassemblies are fastened by a plurality of fixing bolts. .   The speed reduction mechanism includes an input gear attached to the motor shaft of the electric motor, an intermediate gear meshing with the input gear, and an output gear meshing with the intermediate gear, and the gear shaft supporting the intermediate gear is the bag. The electric actuator according to claim 1, wherein the electric actuator is fixed to a housing having a hole.   The electric actuator according to claim 1, wherein a rolling bearing that rotatably supports an input gear attached to a motor shaft of the electric motor is mounted on a housing having the bag hole.   The electric actuator according to claim 1, wherein the pair of support bearings are attached to the housing via a radial clearance.

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