JP4699799B2 - Electric actuator - Google Patents

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. The worm part that meshes with the worm wheel is formed on the tip part side of the motor, and the motor shaft is divided into three parts: the base end part on the motor case side, the intermediate part of the iron core (core) and the worm part, and the tip part on the gear case side And have a structure such that each of them is pivotally supported (see, for example, Patent Document 1).
Japanese Patent Laying-Open No. 2005-030545 (FIG. 1)

  However, in the bearing structure as described above, the tip portion of the motor shaft is only supported rotatably in the insertion hole in the gear case, and a slight gap is generated between the motor shaft and the insertion hole, For this reason, when the motor shaft is driven to rotate, due to the meshing reaction force between the worm portion and the worm wheel, the tip end side of the motor shaft is easily bent (shaking of the shaft), the meshing depth of the worm wheel is reduced, the worm wheel is damaged, etc. Is likely to occur.

  Moreover, since the motor shaft moves in the axial direction by such bending on the motor shaft tip side, particularly when the intermediate portion of the motor shaft is supported by a ball bearing, it is press-fitted and fixed to the motor shaft. The ball bearing inner race is susceptible to rattling due to the thrust load, causing vibration and noise.

  An object of the present invention is to provide an electric actuator capable of reducing the occurrence of vibration and noise due to rattling of an inner race of a ball bearing that is press-fitted and fixed to a motor shaft.

According to the present invention, the above problem is solved as follows.
(1) Construct a motor case and a speed reduction mechanism that constitutes a motor body in which a stator is 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. The motor shaft that faces the gear case is assembled by detachably assembling the worm wheel that is pivotally supported and housed, and extending from the inside of the motor case side through the shaft hole toward the outside of the gear case. A worm portion that meshes with the worm wheel is formed on the tip end side of the motor, and at least the middle portion of the motor shaft is fitted and locked from the inside of the gear case to the enlarged diameter shaft hole that opens to the inner end portion of the shaft hole. that the electric a click Chueta was axially supported by a ball bearing which receives the load in the radial direction, the motor case side, the rotor and is adjacent the press-commutator fixed to the motor shaft is provided with, and the integer Between the inner race of the ball bearing located proximate to each other as a child, is fitted to the motor shaft, a collar made of a rubber elastic ring with a cross-sectional isosceles shape which is flared toward the axial center of the motor shaft, the Rukoto assembled by pressure toward the commutator side to the ball bearing, the inner race of the ball bearing, pressure given toward the commutator side Giake scan side is to be applied.

  According to the first aspect of the present invention, when the motor shaft is driven to rotate, the inner race that tries to move in the axial direction on the motor case side with respect to the outer race of the ball bearing by the meshing reaction force between the worm portion and the worm wheel. Can be suppressed by applying pressure to the collar, thereby preventing vibrations and abnormal noises caused by rattling of the inner race and preventing oil leakage from the lubricant applied to the motor shaft and ball bearing. be able to.

In addition , since the collar is made of a rubber elastic ring having an isosceles trapezoidal cross section that widens toward the center of the motor shaft, the absorption stroke due to the expansion and contraction of the motor shaft in the axial direction can be increased. Absorbs variations in the processing accuracy of components in the axial dimensions of the press-fitted commutator and the depth direction of the motor case, etc., thereby reducing the cost increase by improving the processing accuracy of the conventional components Can be made.

  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. FIG. 5 is an enlarged cross-sectional view of a main part showing an assembled state of a collar on the motor shaft. FIG.

  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 extended and bent outwardly, and these mounting ears (11) and (11) are respectively 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) , first and second ball bearing receives a load La dialkyl direction of the motor shaft (8) (20) (21) is arranged to be locked Hamagogakari.

  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) receives a load in the thrust direction as well as the radial direction of the motor shaft (8), and opens outward on the outer surface of the gear case (16) corresponding to the opposite side of the motor case (3). It is fitted and locked to the radial shaft hole (19) from the outside and pivotally supports the tip end portion (8b) of the motor shaft (8), whereby the base end portion (8a) side of the motor shaft (8) is opened. Thus, the motor shaft (8) is assembled in a cantilever state so as to be supported by only both ends of the worm portion (8c) in the gear case (16).

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). Te, by reducing the axial length of the motor case (3), while achieving an overall reduction in size and weight, and eliminates the need for bearings at the proximal end of the motor shaft (8) (8a), structure The assembling structure is simplified by reducing the number of parts, and costs are reduced.

  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 front end (8b) of the motor shaft (8b) in the thrust-radial direction is suppressed. As a result, when the motor shaft (3) is driven to rotate, Bending on the tip (8b) side of the motor shaft (8) due to the meshing reaction force between the worm part (8c) and the worm wheel (15) is suppressed to prevent the worm wheel (16) from being damaged. Yes.

  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 pressed against the end surface (16a) of the gear case (16) and 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.

  As shown in FIG. 5, the collar (27) is composed of a rubber elastic ring having an isosceles trapezoidal cross section that widens toward the shaft center of the motor shaft (8), and the collar (27) of the first ball bearing (20). The inner race (20a) is assembled so that its one end surface (27a) is in pressure contact, and pressure is always applied to the inner race (20a) in the axial direction facing the outside of the gear case (16). ing.

  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), so that the absorption stroke caused by the expansion and contraction of the motor shaft (8) in the axial direction is reduced. 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. It is a principal part expanded sectional view which shows the interposition state of the collar to a motor shaft.

(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
(27a) One end face

Claims (1)

A worm wheel that constitutes a motor case and a speed reduction mechanism that constitutes a motor body in which a stator is 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 tip of the motor shaft that faces the gear case is assembled in a separable manner from the gear case that is pivotally supported and extended from the inner side of the motor case to the outer side of the gear case through the shaft hole. A radial direction in which a worm portion that meshes with the worm wheel is formed on the side, and at least the middle portion of the motor shaft is fitted and locked from the inside of the gear case to the enlarged diameter shaft hole that opens to the inner end portion of the shaft hole. in was supported by ball bearings to receive a load electric a click Chueta,
Provided on the motor case side is a commutator that is press-fitted and fixed to the motor shaft adjacent to the rotor, and is fitted to the motor shaft between the inner races of the ball bearings that are located close to the commutator. , a collar made of rubber-elastic ring with a cross-sectional isosceles shape which is flared toward the axial center of the motor shaft, by Rukoto assembled by pressure toward the commutator side to the ball bearing, the inner race of the ball bearing , electric actuator, characterized in that pressure given toward the commutator side Giake scan side is to be applied.

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