JP4864341B2 - 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. to the distal end side, to form a worm portion of the worm wheel and meshing, the motor shaft, the base end portion of the motor case side, the middle portion of the iron heart and the worm portion, and at three points of the front end portion of the gear case side Each has a structure that supports the shaft (for example, see Patent Document 1).
Japanese Patent Laying-Open No. 2005-030545 (FIG. 1)

However, the bearing structure as described above, the base end portion of the motor shaft, since it is pivotally supported by a bearing on the end of the motor case, minutes for bearing the base end portion of the motor shaft, the motors shaft The length of the motor case increases, and the end of the motor case also protrudes outward in the axial direction like a umbilicus due to the formation of the storage space of the bearing, so the motor case itself is also longer in the axial direction. The overall size has increased, and the weight has been adversely affected.

In addition, the tip of the motor shaft is only supported rotatably in the insertion hole provided in the gear case , and a slight gap is formed between the motor shaft and the insertion hole. at the time of driving, the engagement reaction force between the worm portion and the worm wheel, the tip end portion side of the motor shaft is easily axial shaking, also under reduced small meshing depth of the worm wheel, easy breakage of the worm wheel occurs. Further , since the motor shaft moves in the axial direction, it is necessary to consider the thrust load at both ends of the motor shaft, and there is a problem that the assembly structure is complicated and the cost is increased.

  The object of the present invention is to support the motor shaft in a cantilevered state only on the gear case side, to reduce the size and weight, to reduce the cost by simplifying the assembly structure, and to break the worm wheel It is an object of the present invention to provide an electric actuator capable of preventing the occurrence of the above.

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 worm wheel that meshes with the worm wheel on the tip side of the motor shaft extended from the motor case through the shaft hole into the gear case. In the electric actuator that formed the part,
A first bearing that supports the middle part of the motor shaft and a second bearing that supports the front end of the motor shaft are arranged in the gear case, and the first bearing is provided on the gear case. The inside of the hole is fitted and locked from the inside to the diameter-expanded shaft hole that is formed and opened in a step, and the second bearing is outside the shaft- shaped diameter-opened shaft hole that is formed and opened to the outside of the shaft hole. Engaging and locking, and
The first and second bearings are ball bearings that receive a load in the thrust-radial direction. The motor shaft is inserted into the inner races of these ball bearings, and is inserted into the inner races of the ball bearings constituting the second bearing. The end of the motor shaft is fastened and fixed from the outside with a nut, and the outer race of the ball bearing that is fitted and locked to the outer diameter expansion shaft hole of the shaft hole is connected to the diameter expansion step of the outer diameter expansion shaft hole. sandwiched and fixed by a cap screwed from the outside to the parts and the outer diameter axial hole,
A collar made of a rubber elastic ring is interposed between the outer race outer surface of the first bearing and the commutator end of the motor body so that the inner races of the first and second bearings are brought close to each other. Pressurize,
The motor shaft is assembled so that it is supported only at both ends of the worm portion in the gear case.

(2) In the above item (1), the stator of the material consists of neo Ji beam system of bonded magnets.

(3) In the above item (1) or (2), the collar is composed of a rubber elastic ring having an isosceles trapezoidal cross section that extends toward the center of the motor shaft.

According to the first aspect of the present invention, since the motor shaft is assembled in a cantilever state so as to be supported by only both ends of the worm portion in the gear case, the axial length of the base end portion of the motor shaft is It is possible to shorten the length of the motor case, and it is not necessary to form a bearing housing space as before, and the length of the motor case in the axial direction can be reduced, thereby reducing the overall size and weight. Can be achieved.
Since a bearing for pivotally supporting the base end portion of the motor shaft is not required, the cost can be reduced by simplifying the assembly structure by reducing the number of components.
Since the tip of the motor shaft inserted from the inside into the shaft hole of the gear case is assembled so that it is supported from the outside of the gear case, the assembly work of the motor shaft to the gear case is easy and simple. Can be done.
The thrust-radial load of the motor shaft is supported by a ball bearing that supports the tip of the motor shaft. Bending of the motor shaft can be suppressed, thereby preventing the worm wheel from being damaged.
The first and second ball bearings supporting the motor shaft are pressurized by a collar interposed between the commutator of the motor shaft and the inner race of the first ball bearing so that the first and second ball bearings come close to each other. The motor shaft bending due to the meshing reaction force between the worm part and the worm wheel during the rotation drive of the motor shaft can be further suppressed, and oil leakage of the lubricant applied to the motor shaft and ball bearing can be prevented. Yes.

  In addition, the collar is made of a rubber elastic ring with an isosceles trapezoidal cross section that expands toward the center of the motor shaft, so the absorption stroke due to expansion and contraction in the axial direction of the motor shaft is expanded and press-fitted and fixed to the motor shaft. Absorbs variations in machining accuracy of component parts in the axial dimension of the commutator and the depth dimension of the motor case, etc., and is long in the axial direction, resulting in less oil leakage and improving the machining accuracy of conventional components. The high cost due to is reduced.

  According to the invention described in claim 2, since the magnetic force of the stator can be increased and the thickness of the stator can be reduced based on the same output as before, the diameter of the motor case can be reduced. In addition, the width in the axial direction of the iron core constituting the rotor can be narrowed, and thereby the overall size and weight can be reduced.

  According to the invention described in claim 3, since the collar is formed of a rubber elastic ring having a cross-section isosceles trapezoidal shape that spreads toward the shaft center of the motor shaft, an absorption stroke due to expansion and contraction in the axial direction of the motor shaft is increased. Absorbs variations in the machining accuracy of components in the axial dimension of the commutator that is press-fitted and fixed to the motor shaft and the depth dimension of the motor case, etc., and is long in the axial direction, so there is less oil leakage in the axial direction. The high cost due to the improvement of the processing accuracy of the component parts as before.

  Hereinafter, the present invention will be described in detail with reference to 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, FIG. 2 is an exploded perspective view of a motor body and a speed reduction mechanism, and FIG. Sectional drawing which shows the assembly state of the motor case and gear case seen from the arrow direction in the III-III line, FIG. 4 shows the assembly state of the motor case and the gear case in the IV-IV line of FIG. It is a principal part expanded sectional view.

  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 made of an aluminum alloy, and the motor case (3). a stator consisting of a fixed neo Ji beam system of bonded magnet to the inner circumferential surface (Nd-Fe-B magnet) (4), the stator (4) iron core is facing radially inner surface of the (5 a coil (6) a rotor which is formed by winding a (7)), the rotor (7) is Tei Ru motor shaft is press-fitted and (8), which is press-fitted to the motor shaft (8) A commutator (9) and a brush unit (10) for supplying power to the commutator (9) are provided.

  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). ) Is arranged so as to be in sliding contact with the axis of the commutator (9) at right angles.

  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 open end of the motor case (3) has an inner peripheral edge (3a) processed into a curved surface and is opposed to a diagonal line in the radial direction with respect to the axis of the motor shaft (8). The pair of mounting ears (11) and (11) are formed so as to be bent outwardly and symmetrically projecting so that these mounting ears (11) and (11) are respectively tightened. An aluminum cast gear case for the speed reduction mechanism (A) in which the worm wheel (15) pivotally supported by the shaft (14) is accommodated through the bolt (12) (12) and the rubber elastic O-ring (13). The motor case (3) and the gear case (16) are integrally assembled so as to be separable.

The motor shaft (8) is inserted into the shaft hole (17) formed through said gear case (16), and extending in the axial direction so as to face the gear case (16) in its gear case ( the distal end (8b) side facing the inside 16), said worm wheel (15) and the worm portion which meshes (8c) are engraved. The base end portion (8a) of the motor shaft (8) in the motor case (3) is sufficiently thick so as to have enough rigidity to withstand the weight of the rotor (7) to be press-fitted and fixed. The shaft diameter is as follows.

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 ball bearings (20) and (21), which are first and second bearings that receive the load in the thrust-radial direction of the motor shaft (8), are fitted and locked.

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

Said second ball bearing (21), the outside diameter shaft hole opened (19) on the outer surface of the opposite side der Ru gear case of the motor case (3) (16), to airtightly fitted engagement from the outside , journaled tip of the motor shaft (8) and (8b), thereby, the base end portion of the motor shaft (8) (8a) side opened and a connexion, the motor shaft (8), the gear case (16 The bearings are cantilevered 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 can be reduced, and the bearing at the base end (8a) of the motor shaft (8) is not required. 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. It is inserted into the inner race (21a) of the second ball bearing (21) to be fitted and protrudes outward, and a nut (22) is screwed into the protruding end from the outside, and the inner race (21a ) it is adapted to be fastened and fixed to, thereby, the movement of the thrust direction of the motor shaft (8) is suppressed.

The fitting engagement sealed Tei Ru outer race outside diameter shaft hole (19) (21b) has a diameter stepped portion in the inner back of the outer diameter axial hole (19), from the outside of the axial hole (17) and by Tei Ru cap screwed to the outside diameter shaft hole (19) (23) is sandwiched and fixed, I fastened coupled with the inner race (21a) by the nut (22), the motor shaft (8) thrust at the tip (8b) - and suppresses movement in the radial direction, thereby, when the rotation driving of the motor shaft (8), the motor shaft by meshing reaction force of the worm portion and (8c) and worm wheel (15) Bending on the tip (8b) side of (8) 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). are protruded, as shown in FIG. 4, the outer peripheral surface of the socket portion (24) (24a), and inserted by keeping taut while expanding the elastomeric O-ring (13), then 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 circumferential surface (24a) of the motor has a circular cross section slightly larger than the area of the space (S), and the motor case (3) has an open end on the receiving portion (24) when assembled. The outer peripheral surface (24a) of the motor case (3) is crushed and deformed elastically by the pressing force caused by the contact of the inner peripheral edge (3a) of the motor case (3). The slightest gap (a) between the inner peripheral surface of the motor case (3) and the outer peripheral surface (24a) of the receiving portion (24) of the gear case (16) After the motor case (3) is positioned so that the inner peripheral edge (3a) of the open end is pressed evenly in the radial direction and the gap (a) is constant in the circumferential direction, the motor case Installation of (3) This is done by pressing the ears (11) (11) against the end face (16a) of the gear case (16) and simultaneously fastening them with fastening bolts (12) (12). ) and centering between the gear case (16) is able to perform accurately.

  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 widens toward the axis of the motor shaft (8), and is formed on the inner race (20a) of the first ball bearing (20). its one end surface is assembled so as to press said against the inner race (20a), facing the inner race (21a) side of the second ball bearing (21), on the outside of the gear case (16) A pressurized pressure is always applied in the axial direction.

  As a result, the inner races (20a) and (21a) in the ball bearings (20) and (21) receiving the loads in the first and second thrust-radial directions are mutually inward due to the elastic force of the collar (27). The close pressure is applied, and the outer race (21b) of the second ball bearing (21) is fixed to the gear case (16), whereby the first and second ball bearings (20) (21 ) Of the inner race (20a) (21a) absorbs the rattle in a state of being pressurized with each other. As a result, when the motor shaft (8) is driven to rotate, the worm portion (8c) and the worm wheel (15) The inner race (20a) that attempts to move in the axial direction on the motor case (3) side against the outer race (20b) of the ball bearing (20) by the meshing reaction force is suppressed by the pressure applied by the collar (27). In addition, vibrations and abnormal noise caused by rattling of the inner race (20a) are prevented and This prevents oil leakage (applying to the commutator side) of the lubricating oil applied to the rotor shaft (8) and 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. Expands and absorbs variations in the machining accuracy of components in the axial dimension of the commutator (9) press-fitted and fixed to the motor shaft (8) and the depth dimension of the motor case (3), and the axial direction Therefore, the oil leakage is small and the cost is increased by improving the processing accuracy of the conventional component parts.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a longitudinal side view showing an embodiment of an electric actuator 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 a motor case and a 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.

(1) Electric actuator
(2) Motor body
(3) Motor case
(3a) Inner peripheral edge
(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 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 gear case that is pivotally supported and housed is separably assembled, and the worm part that meshes with the worm wheel is formed on the tip side of the motor shaft that extends from the motor case through the shaft hole into the gear case. In the electric actuator
A first bearing that supports the middle part of the motor shaft and a second bearing that supports the front end of the motor shaft are arranged in the gear case, and the first bearing is provided on the gear case. The inside of the hole is fitted and locked from the inside to the diameter-expanded shaft hole that is formed and opened in a step, and the second bearing is outside the shaft- shaped diameter-opened shaft hole that is formed and opened to the outside of the shaft hole. Engaging and locking, and
The first and second bearings, thrust - a ball bearing Tona shall receive the load in the radial direction, to insert the motor shaft to the inner race of the ball bearing, the ball bearing forming the second bearing inner The front end of the motor shaft inserted into the race is fastened and fixed from the outside by a nut, and the outer race of the ball bearing fitted and locked to the outer diameter-expanded shaft hole of the shaft hole is fixed to the outer diameter- expanded shaft hole. It is clamped and fixed by the cap screwed from the outside to the outside diameter stepped portion and the outside diameter expanding shaft hole,
A collar made of a rubber elastic ring is interposed between the outer race outer surface of the first bearing and the commutator end of the motor body so that the inner races of the first and second bearings are brought close to each other. Pressurize,
An electric actuator characterized in that a motor shaft is assembled so as to be supported only at both ends of a worm portion in a gear case. Stator, the electric actuator according to claim 1, wherein comprising a neodymium-based bonded magnet.   3. The electric actuator according to claim 1, wherein the collar is formed of a rubber elastic ring having an isosceles trapezoidal cross-section that expands toward the center of the motor shaft.

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