JPH083158Y2 - Electric motor bearing device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial field of application) The present invention relates to a bearing device for an electric motor, particularly a small horsepower permanent magnet DC electric motor.

Prior Art Small horsepower PMDC motors are being used increasingly in low noise environments, such as inside the seats of luxury cars. Therefore, it is becoming increasingly important to reduce the mechanical noise of such electric motors. Typically, the motor shaft rotates with a pair of sintered self-aligning bearings. Since the clearance between the shaft and the bearing is required, it means that the shaft rattles laterally at the bearing and causes a large amount of mechanical noise. One device proposed to overcome this urges the magnetic field of the stator to one side of the axis of the motor shaft so that the shaft is pressed to one side of the bearing inner surface. This requires changing the shape of the electric motor, and there are other drawbacks.

(Construction of the Invention) The present invention comprises a frame or housing for holding a stator and having self-aligning bearings at both ends, each bearing
A bearing having an inner surface of the bearing cylinder, further comprising a rotor comprising a shaft, a commutator and an armature mounted on the shaft, and rotatably attached to the bearing so that the shaft rotates on the inner surface of the bearing cylinder. Is provided with at least one torsional force of the bearing to urge the bearing to a position where the axial direction of the inner surface of the bearing cylinder forms an angle with the axial direction of the shaft. Means are provided.

By twisting the axis line of the inner surface of the bearing with respect to the shaft, the gap between the inner surface of the bearing and the shaft is reduced, and rattling of the shaft in the bearing can be reduced.

The present invention will be further described by way of example with reference to the accompanying drawings.

(Example) A drawing is demonstrated. The motor shaft 2 holds a commutator and an armature (not shown). The shaft 2 is supported at its shaft ends by two self-aligning bearings 4. The bearings are respectively held by an end cap 6 of the electric motor and a closed end of a deep-drawn steel can-like case (not shown). The end cap 6 and the case form a motor housing. The end cap 6 also holds the brush gear 6 (not shown) and the case holds the permanent magnets forming the motor stator.

Each bearing 4 has a bearing cylindrical inner surface 8 which is chamfered at its outer end 10. The outer surface 12 of the bearing 4 is partially spherical or spheroidal, and circular in plan view (second
FIG. 1), which is arch-shaped in the axial direction sectional view (FIG. 1).
The bearings 4 are respectively housed in cups 14 formed on the end cap or the end wall of the case. The bearing 4 is held in place by a steel spring clip 15, which surrounds the bearing and has elastic fingers 16 which exert a force on the outer surface 12 to press the bearing against the cup 14. One of the fingers 16a exerts a force on a step 18 formed on the outer surface 12 of the bearing. Finger 16a
The axis BB of the inner surface 8 of the bearing cylinder is the axis S-S of the shaft 2.
Form an angle (ie parallel or not coincident)
Thus, to rotate the bearing within the cup 14, it is configured to apply a torsional force, or torque, to the bearing.

The clip 15 has an upwardly facing circumferential lip 20 which grips the circumferential wall 22 of the end cap 6 to hold the clip 15 in place. The fingers 16a are elastic and apply only a small amount of force so that the bearing 4 can maintain its self-centering characteristics and twist along the axial direction of the shaft, but the bearing does not move against the shaft. It is subjected to preload applied by fingers 16a which tilt the bearing by an angle. Typically, the axis of this bearing is at an angle of about 0.5 degrees to the axis of the shaft.

By varying the non-limiting shape of fingers 16a, different preloads, or torques, can be applied to the bearing. A range of clips 15 are provided to allow for preload selection, or one clip may have several fingers 16a of different shapes, one of which exerts a force on step 18. To be selected.

FIG. 3 will be described. When applying a biasing force to both bearings, they are preferably tilted in opposite directions relative to the shaft.

Various modifications can be made to the described embodiments, and all such modifications are included in the utility model registration claim.

[Brief description of drawings]

FIG. 1 is a partial cross-sectional view of an end portion of a PMDC motor housing showing a rotor shaft mounted in a bearing device according to the present invention. FIG. 2 is a plan view seen from the arrow A in FIG. FIG. 3 is a schematic diagram of a motor shaft and two bearings. 2 …… Shaft 4 …… Self-aligning bearing 6 …… Housing 8 …… Bearing cylinder inner surface 12 …… Bearing outer surface 14 …… Cup 15 …… Clip 16 …… Finger 18 …… Step

Claims (6)

[Scope of utility model registration request] 1. A frame or housing 6 for holding a stator and having self-aligning bearings 4 at both ends, each bearing 4 having a bearing cylindrical inner surface 8, a shaft 2 and a shaft 2 above. The rotor further comprises a commutator and an armature attached to the shaft, and the shaft 2 has the inner surface 8 of the bearing cylinder.
In the electric motor rotatably mounted on the bearing 4 so as to rotate in the axial direction, the bearing is urged to a position where the axial direction B-B of the inner surface 8 of the bearing cylinder forms an angle with the axial direction S-S of the shaft 2. In order to do so, an electric motor is provided, which is provided with biasing means 15, 16a, 18 for applying a torsional force to at least one of the bearings 4. 2. The urging means 15, 16a, 18 apply a force to one side of the bearing 8 to act in a direction substantially parallel to the axial direction BB of the bearing 4. 1) The electric motor described. 3. The electric motor according to claim 2, wherein the urging means is an elastic finger 16a which applies a force to the bearing 4. 4. A bearing (4) is placed in a cup (14) and is held in place by a clip (15) having a plurality of resilient fingers (16) that exert a force on the bearing to retain the bearing in the cup (14), at least in that finger. The electric motor according to claim 3, wherein one of the 16a is configured to apply a biasing force. 5. The electric motor according to claim 1, wherein a twisting force is applied to both bearings. 6. The electric motor according to claim 5, wherein the bearing 4 is twisted in the opposite direction with respect to the shaft 2.