JP2006311657A - Electric actuator - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electric actuator in which a motor case and a gear case can be aligned with high accuracy, productivity is enhanced at a low cost by reducing vibration of the motor case, and attachment work can be carried out easily and conveniently. <P>SOLUTION: A tubular bottomed motor case 3 and a gear case 16, for containing a worm wheel 15 while pivoting, are attached separably. A worm section 8c gearing with the worm wheel is formed on the distal end 8b side of a motor shaft 8 extended into the gear case. On the end face 16a of the gear case that touches the opening end side of the motor case, a rubber elastic O-ring 13 is fitted under stretched state to the outer circumferential surface 24a of a tubular receiving window 24 formed to project concentrically to the central axis of the motor shaft. The rubber elastic O-ring is interposed to deformably collapse, in a space S surrounded by the inner circumferential edge 3a at the opening end of the motor case, the end face of the gear case, and the outer circumferential surface of the receiving window. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an electric actuator used in a drive system such as a power tailgate or a power slide door of an automobile, and more particularly to a small motor type electric actuator.

  Since such an electric actuator has restrictions on the installation space on the vehicle body, the loading weight, and the like, it is desired to reduce the size and weight as well as improve the output.

In the conventional electric actuator, the motor case constituting the motor main body and the gear case accommodating the worm wheel constituting the speed reduction mechanism are assembled in a separable manner, and the motor shaft of the motor main body facing the gear case from inside the motor case. A worm part that meshes with the worm wheel is formed on the front end side of the motor, and a stator is fixed to the inner peripheral surface of the motor case, and the inner peripheral surface of the stator is press-fitted and fixed to the base end side of the motor shaft. The rotor is assembled so as to face the rotor in the radial direction (see, for example, Patent Document 1).
Japanese Patent Laying-Open No. 2005-030545 (FIG. 1)

  However, in the assembly structure as described above, when the motor case is assembled to the gear case, if both are made of metal such as an aluminum alloy, it is difficult to perform assembly by press-fitting. It is necessary to hold the motor case, and the motor case is likely to vibrate.

  In addition, if there is an error in the processing accuracy of the motor case with respect to the gear case, the clearance between the stator and the rotor cannot be kept constant because it promotes variations in the assembly accuracy of the two. The misalignment causes variations in motor performance.

  In addition, in order to increase the assembly accuracy between the gear case and the motor case, it is necessary to extremely increase the processing accuracy of both, which not only increases costs, but also reduces productivity and assembly work. there were.

  The object of the present invention is that the processing accuracy between the motor case and the gear case can be accurately adjusted without extremely increasing the processing accuracy, and the vibration of the motor case can be reduced, resulting in low cost and high productivity. An object of the present invention is to provide an electric actuator that can be improved and can be assembled easily and easily.

According to the present invention, the above problem is solved as follows.
(1) A bottomed cylindrical motor case that constitutes a motor body having a stator fixed so as to face a rotor that is press-fitted and fixed to the base end side of the motor shaft on the inner peripheral surface in a radial direction; The worm wheel constituting the speed reduction mechanism is pivotally supported and housed in a separable manner, and the worm wheel is attached to the front end portion of the motor shaft that extends from the motor case into the gear case. In the electric actuator having a meshed worm portion, a cylindrical receiving portion is formed concentrically around the central axis of the motor shaft on the end surface of the gear case that is in contact with the opening end side of the motor case. A rubber elastic O-ring is inserted into the outer peripheral surface of the motor case while maintaining a tension state, and the rubber elastic O-ring is formed between the inner peripheral edge of the opening end of the motor case and the outer peripheral surface of the end surface of the gear case and the receiving portion. Go shape A space which is crushing deformable to interposed.

(2) In the above item (1), the inner peripheral edge of the opening end of the motor case is formed on the R surface, and the rubber elastic O-ring includes the inner peripheral edge of the opening end of the motor case, the end face of the gear case, and the receiving part. The cross-sectional circular shape is at least slightly larger than the area of the space formed by the outer peripheral surface of the space.

(3) In the above item (1) or (2), the pair of mounting ears are bent outward at the opening end of the motor case so as to be opposed to each other on the diagonal in the radial direction with respect to the motor shaft. The motor case provided with these mounting ears is fastened and assembled so that the open end of the motor case is pressed against the end face of the gear case in a two-point support state.

  According to the first aspect of the present invention, the restoring force due to the crushing deformation of the rubber elastic O-ring acts so as to evenly press the inner peripheral edge of the opening end of the motor case outward in the radial direction. Since the motor case can be positioned so that the gap between the surface and the outer peripheral surface of the receiving portion of the gear case is constant in the circumferential direction, the motor case and the gear case can be accurately aligned. . Thereby, since it is not necessary to raise extremely the processing precision of a motor case and a gear case, cost reduction and productivity improvement can be aimed at. Further, the vibration of the motor case can be reduced by the rubber elastic O-ring interposed in the space formed by the inner peripheral edge of the opening end of the motor case and the outer peripheral surface of the gear case end face and the receiving port. it can.

  According to the invention described in claim 2, the restoring force due to the crushing deformation of the rubber elastic O-ring can be reliably transmitted to the inner peripheral edge of the opening end of the motor case, and the alignment accuracy between the motor case and the gear case is improved. be able to.

  According to the invention described in claim 3, since the motor case can be assembled to the gear case in a two-point support state, the number of components can be reduced, and the assembly work of the motor case can be performed easily and simply. be able to.

  DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail with reference to the drawings. FIG. 1 is a longitudinal side view showing an embodiment of an electric actuator according to the present invention with a part of a motor shaft cut away, and FIG. 3 is an exploded perspective view of the mechanism, FIG. 3 is a cross-sectional view showing the assembled state of the motor case and the gear case as seen from the direction of the arrow in the line III-III in FIG. 1, and FIG. It is a principal part expanded sectional view which shows the assembly | attachment state of the motor case and gear case in a wire.

  The electric actuator (1) of the present embodiment is formed by integrating a small motor main body (2) and a speed reduction mechanism (A). First, the motor main body (2) of the main part will be described in detail. explain.

  As shown in FIGS. 1 and 2, the motor body (2) includes, for example, a thin motor case (3) that is deep-drawn into a bottomed cylindrical shape with an aluminum alloy, and the motor case (3). A stator (4) made of a neodymium-based bond magnet (Nd—Fe—B magnet) fixed to the inner peripheral surface, and an iron core (5) opposed to the inner diameter surface of the stator (4) in the radial direction. A rotor (7) formed by winding a coil (6), a motor shaft (8) to which the rotor (7) is press-fitted and fixed, and a commutator (press-fixed to the motor shaft (8) ( 9) and a brush unit (10) for supplying power to the commutator (9).

  As shown in FIG. 3, the brush unit (10) includes an insulator (10a) and a brush (10c) assembled to the insulator (10a) via a brush holder (10b). ) Are arranged so as to be in sliding contact perpendicular to the axis of the commutator (9).

  The rotor (7) is press-fitted and fixed to the base end (8a) side of the motor shaft (8), and the commutator (9) is attached to the motor shaft (8) on the opening end side of the motor case (3). It is press-fitted and fixed adjacent to the rotor (7).

  As shown in FIG. 4, the opening end of the motor case (3) has an inner peripheral edge (3a) processed into an R surface and is on a diagonal line in the radial direction with respect to the axis of the motor shaft (8). A pair of mounting ears (11) and (11) are formed so as to be symmetrically projected outwardly by bending so that these mounting ears (11) and (11) are respectively positioned. Made of aluminum casting of the speed reduction mechanism (A) in which the worm wheel (15) pivotally supported by the shaft (14) is accommodated through the tightening bolts (12) and (12) and the rubber elastic O-ring (13) It is attached to the end surface (16a) of the gear case (16), and thereby, the motor case (3) and the gear case (16) are integrally assembled so as to be separable.

  The motor shaft (8) is inserted into a shaft hole (17) formed through the gear case (16) and extends in the axial direction so as to face the gear case (16). A worm portion (8c) that meshes with the worm wheel (15) is engraved on the tip portion (8b) side facing the gear case (16), and the motor case (3) The base end portion (8a) of the motor shaft (8) in the inside has a shaft diameter of a certain thickness so as to be rigid enough to withstand the weight of the rotor (7) to be press-fitted and fixed. Is set.

  The inner and outer ends of the shaft hole (17) in the axial direction have stepped diameter-expanded shaft holes (18) and (19), and both the inner and outer diameter-expanded shaft holes (18) and (19) The first and second ball bearings (20) and (21) receiving the load in the thrust-radial direction of the motor shaft (8) are arranged to be fitted and locked.

  The first ball bearing (20) is fitted and locked in an inner diameter-expanded shaft hole (18) opened on the inner surface of the gear case (16) corresponding to the motor case (3) side, so that the motor shaft (8 ), That is, between the base end (8a) side where the iron core (5) and the commutator (9) are press-fitted and the worm portion (8c).

  The second ball bearing (21) is fitted and locked from the outside to the outer diameter-expanded shaft hole (19) opened on the outer surface of the gear case (16) corresponding to the opposite side of the motor case (3). The motor shaft (8) is supported by the gear case (16) so that the tip end portion (8b) of the motor shaft (8) is pivotally supported, so that the base end portion (8a) side of the motor shaft (8) is opened. ) In a cantilevered state so that it is pivotally supported only at both ends of the worm portion (8c).

  This shortens the axial length of the base end portion (8a) of the motor shaft (8), and eliminates the need to form a conventional bearing storage space at the end portion of the motor case (3). By reducing the axial length of the motor case (3), the overall size and weight of the motor case (8) can be reduced, and bearings at the base end (8a) of the motor shaft (8) are not required. This simplifies the assembly structure and reduces costs.

  The front end portion (8b) of the motor shaft (8) is a reduced diameter shaft whose outer peripheral surface is threaded, and the outer diameter expansion shaft hole (19) of the shaft hole (17) from the outside. The inner race (21a) of the second ball bearing (21) to be fitted is press-fitted and protruded outward, and a nut (22) is screwed into the protruding end from the outside, and the inner race (21a ) To prevent the motor shaft (8) from moving in the thrust direction.

  The outer race (21b) fitted and locked in the outer diameter-expanded shaft hole (19) is clamped and fixed by a cap (23) screwed into the shaft hole (17) from the outside, and the nut (22) The inner race (21a) is fastened and fixed, and the movement of the tip (8b) of the motor shaft (8b) in the thrust-radial direction is suppressed. As a result, when the motor shaft (8) is driven to rotate, the worm Bending on the tip end (8b) side of the motor shaft (8) due to the meshing reaction force between the portion (8c) and the worm wheel (15) is suppressed to prevent the worm wheel (16) from being damaged. .

  On the end surface (16a) of the gear case (16) that contacts the opening end side of the motor case (3), a cylindrical receiving portion (24) is formed concentrically around the central axis of the shaft hole (17). As shown in FIG. 4, it is inserted into the outer peripheral surface (24a) of the receiving portion (24) so as to maintain the tension state while expanding the rubber elastic O-ring (13), Then, the inner peripheral edge (3a) of the open end of the motor case (3) is fitted, and the mounting ears (11) (11) are brought into close contact with the end surface (16a) of the gear case (16), and then tightened. By fastening with the attached bolts (12) and (12), the motor case (3) is assembled to the gear case (16) in a two-point supported state.

  In other words, the rubber elastic O-ring (13) includes the inner peripheral edge (3a) of the opening end of the motor case (3) and the receiving portion (24) of the gear case (16) as shown by a two-dot broken line in FIG. The outer peripheral surface (24a) of the outer circumferential surface (24a) has a circular cross section that is at least slightly larger than the area of the space (S) formed in an encircling manner. When the outer peripheral surface (24a) of (24) is pressed and fitted, it is elastically crushed and deformed by the pressing force caused by the contact of the inner peripheral edge (3a) of the motor case (3). Part of the motor case (3) and the outer peripheral surface (24a) of the receiving part (24) of the gear case (16) are bitten into a slight gap (a) and restored. After the positioning of the gap (a) so that the gap (a) is constant in the circumferential direction, the inner peripheral edge (3a) of the opening end of the motor case (3) is pressed evenly in the radial direction by force. ,motor The mounting ears (11) and (11) of the case (3) are brought into pressure contact with the end surface (16a) of the gear case (16) and are fastened simultaneously with fastening bolts (12) and (12). As a result, the shaft centering of the motor case (3) and the gear case (16) can be accurately aligned.

  An annular recess (25) is formed on the inner peripheral surface of the receiving portion (24) formed to protrude from the inner surface of the gear case (16), and the commutator (25) is formed in the annular recess (25). The insulator (10a) of the brush unit (10) that holds the brush (10c) that is in sliding contact with the axis 9) is assembled by a bolt (26).

  As shown in FIG. 1, the first ball bearing (20) pivotally supporting the intermediate portion of the motor shaft (8) is close to the commutator (9) press-fitted and fixed to the motor case (3) side. The collar (27) is interposed in the motor shaft (8) between them.

  The collar (27) is composed of a rubber elastic ring having an isosceles trapezoidal cross-section that expands toward the center of the motor shaft (8), and is attached to the inner race (20a) of the first ball bearing (20). The pressure is applied to the inner race (20a) in the axial direction that always faces the outer side of the gear case (16) by assembling so that the one end face is in pressure contact.

  As a result, when the motor shaft (8) is driven to rotate, the motor case (3) against the outer race (20b) of the ball bearing (20) by the meshing reaction force between the worm portion (8c) and the worm wheel (15). ) Side inner race (20a) that tends to move in the axial direction is restrained by the pressure applied by the collar (27), to prevent vibration and noise due to rattling of the inner race (20a), and to prevent the motor shaft (8) Prevents oil leakage from the lubricant applied to the ball bearing (20).

  In addition, the collar (27) is made of a rubber elastic ring having an isosceles trapezoidal cross section that widens toward the center of the motor shaft (8). Enlarging and absorbing variations in the machining accuracy of the components in the axial dimension of the commutator (9) press-fitted to the motor shaft (8) and the depth dimension of the motor case (3), etc. High cost due to improved machining accuracy of components.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a longitudinal side view showing an electric actuator according to an embodiment of the present invention with a part of a motor shaft cut away. It is a disassembled perspective view of a motor main body and a reduction mechanism. It is sectional drawing which shows the assembly | attachment state of the motor case and gear case seen from the arrow direction in the III-III line | wire of FIG. FIG. 4 is an enlarged cross-sectional view of a main part showing an assembled state of the motor case and the gear case taken along line IV-IV in FIG. 3.

Explanation of symbols

(1) Electric actuator
(2) Motor body
(3) Motor case
(3a) Opening edge inner edge (R surface)
(4) Stator
(5) Iron core
(6) Coil
(7) Rotor
(8) Motor shaft
(8a) Base end
(8b) Tip
(8c) Worm part
(9) Commutator
(10) Brush unit
(10a) Insulator
(10b) Brush holder
(10c) Brush
(11) Mounting ear
(12) Tightening bolt
(13) Rubber elastic O-ring
(14) Axis
(15) Warm wheel
(16) Gear case
(16a) End face
(17) Shaft hole
(18) Inner diameter expansion shaft hole
(19) Outer diameter expansion shaft hole
(20) First ball bearing
(20a) Inner race
(20b) Outer race
(21) Second ball bearing
(21a) Inner race
(21b) Outer race
(22) Nut
(23) Cap
(24) Receiving part
(24a) Outer surface
(25) Annular recess
(26) Bolt
(27) Color

Claims (3)

A bottomed cylindrical motor case that constitutes a motor main body having a stator fixed thereto so as to face the rotor press-fitted and fixed to the base end side of the motor shaft on the inner peripheral surface, and a speed reduction mechanism A worm wheel that meshes with the worm wheel on the front end side of the motor shaft that extends from the motor case into the gear case. In the electric actuator that formed the part,
A cylindrical receiving part is formed concentrically around the center axis of the motor shaft on the end face of the gear case where the opening end side of the motor case contacts, and a rubber elastic O-ring is tensioned on the outer peripheral surface of the receiving part. The rubber elastic O-ring can be crushed and deformed in the space formed by the inner peripheral edge of the opening end of the motor case and the outer peripheral surface of the gear case and the outer peripheral surface of the receiving portion while maintaining the state. An electric actuator characterized by being interposed.   A space in which the inner peripheral edge of the opening end of the motor case is formed on the R surface and the rubber elastic O-ring is formed by the inner peripheral edge of the opening end of the motor case and the outer peripheral surface of the end face of the gear case and the receiving part. The electric actuator according to claim 1, wherein the electric actuator has at least a slightly larger circular sectional shape with respect to the area. At the opening end of the motor case, a pair of mounting ears are bent outwardly so as to be opposed to each other on a diagonal line in the radial direction with respect to the motor shaft. The electric actuator according to claim 1 or 2, wherein the opening end of the motor case provided is fastened and assembled so as to be in pressure contact with the end surface of the gear case in a two-point support state.

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