Fan, motor and bearing structure thereof

A bearing structure, which is cooperated with a shaft, includes a housing, a bearing, an elastic element and a blocking element. The shaft passes through the bearing. The elastic element presses against the bearing to provide a pre-stress to the bearing. The blocking element is apart from the bearing by a predetermined distance.

CROSS REFERENCE TO RELATED APPLICATIONS

This Non-provisional application claims priority under 35 U.S.C. §119(a) on Patent Application No(s). 095118730 filed in Taiwan, Republic of China on May 26, 2006, the entire contents of which are hereby incorporated by reference.

BACKGROUND OF THE INVENTION

1. Field of Invention

The invention relates to a fan, a motor and a bearing structure thereof. In particular, the invention relates to a fan, a motor and its bearing structure that provides a pre-stress to the bearing.

2. Related Art

In the modem information era, electronic equipment has become an indispensable part of daily life and work. Motors in particular are widely used in various electronic devices to effectively convert electrical energy into mechanical energy.

There are many types of motors.FIG. 1shows a conventional brushless motor1. The brushless motor1includes a housing10, a rotor structure11and a stator structure12. The rotor structure11has a shaft111passing through the housing10. The stator structure12has a coil set121, which fits around with the housing10. An annular magnet112of the rotor structure11is disposed corresponding to the coil set121. The interaction between the coil set121and the magnet112generate an alternated magnetic field to rotate the rotor structure11.

To make the motor1operate smoothly, a bearing13is generally used to cover the shaft111. Consequently, the shaft111rotates well with the support of the bearing13. As well, the bearings13can be classified into ball bearings, sleeve bearings and sliding bearings according to the structures thereof. Take the ball bearing as an example that has an inner ring131, an outer ring132and a ball133. The inner ring131is mounted on the shaft111. The outer ring132is connected to the housing10. The ball133is disposed between the inner ring131and the outer ring132. In order to make the shaft111run more smoothly with the support of the bearing13, the motor1further includes an elastic element14disposed between the bearing13and a cover15. As shown inFIG. 1, the elastic element14presses against the inner ring131of the bearing13to provide a pre-stress to the bearing13so as to make the ball133of the bearing13maintains linear contact with the inner ring131and the outer ring132simultaneously. This mechanism buffers the axial load variation to the bearing13under the high-speed rotation of the shaft111, thereby elongating the lifetime of the motor1. According to the different configurations, the elastic element14can press against the outer ring132of the bearing13as well that provides pre-stress on the bearing13as shown inFIG. 2.

However, a spring is used as the elastic element14generally. After a long-time use of the motor1, the continuous pressure imposed on the bearing13is easy to cause elastic fatigue for the elastic element14. This seriously shortens the lifetime of use of the motor1.

Therefore, it is an important subject to provide a fan, a motor and a bearing structure thereof that can provide a pre-stress to the bearing and prevent the elastic element from being overly pre-stressed and damaged.

SUMMARY OF THE INVENTION

In view of the foregoing, the invention is to provide a fan, a motor and a bearing structure thereof that can provide a pre-stress to the bearing and prevent the elastic element from being overly pre-stressed and damaged.

To achieve the above, the invention discloses a bearing structure, which cooperates with a shaft and is disposed in a housing. The bearing structure includes a bearing, an elastic element and a blocking element. The shaft passes through the bearing, and the elastic element presses against the bearing to provide a pre-stress to the bearing. The blocking element is separated from the bearing by a predetermined distance.

To achieve the above, the invention discloses a motor, which includes a housing, a rotor structure, a stator structure and a bearing structure. The rotor structure has a shaft passing through the housing. The stator structure is disposed corresponding to the rotor structure and is fit with the housing. The bearing structure, which cooperates with the shaft and is disposed in the housing. The bearing structure includes a bearing, an elastic element and a blocking element. The shaft passes through the bearing, and the elastic element presses against the bearing to provide a pre-stress to the bearing. The blocking element is separated from the bearing by a predetermined distance.

To achieve the above, the invention discloses a fan, which includes an impeller, a housing, a rotor structure, a stator structure and a bearing structure. The impeller includes a hub and a plurality of blades disposed around the hub. The rotor structure has a shaft, which passes through the housing and connects to the hub. The stator structure is disposed corresponding to the rotor structure and is fit with the housing. The bearing structure, which cooperates with the shaft and is disposed in the housing. The bearing structure includes a bearing, an elastic element and a blocking element. The shaft passes through the bearing, and the elastic element presses against the bearing to provide a pre-stress to the bearing. The blocking element is separated from the bearing by a predetermined distance.

As mentioned above, the invention discloses a fan, a motor and a bearing structure thereof. The blocking element is separated from the bearing by a distance. The elastic element presses against the bearing. The blocking element has a recess for accommodating the elastic element. Therefore, if the shaft of the motor or fan rotates at a high-speeded rotation and moves toward an axial direction, the elastic element provides a pre-stress to the bearing. The blocking element is used to prevent from doing excessively the pre-stress on the elastic element if the bearing is impacted. This effectively prevents the elastic element, such as a spring, from being damaged during the impact. Therefore, the invention can provide a better protection for the bearing structure and elongate the lifetime thereof.

DETAILED DESCRIPTION OF THE INVENTION

As shown inFIG. 3, a bearing structure20according to a preferred embodiment of the invention includes a bearing21, an elastic element22and a blocking element23. The bearing structure20is cooperated with a shaft and is disposed in a housing25. The housing25consists of a first housing251and a second housing252.

The shaft24passes through the bearing21. In this embodiment, the bearing21, such as a ball bearing, includes an inner ring211, an outer ring212and a ball213. The inner ring211is fit with the shaft24. The outer ring212is connected to the first housing251. The ball213is disposed between the inner ring211and the outer ring212.

The elastic element22presses against the bearing21to provide a pre-stress to the bearing21. In this embodiment, the elastic element22is, for example, a spring or a flexible sleeve.

The blocking element23is disposed adjacent to the bearing21and connected to one end of the first housing251or alternatively integrated with the first housing251. In this embodiment, the blocking element23and the first housing251can be integrally formed by die casting or injection molding. A recess26is formed between the blocking element23and the first housing251to accommodate the elastic element22. One end of the blocking element23is separated from the bearing21by a predetermined distance G If the shaft24rotates and moves toward an axial direction D, the bearing21is pulled toward the elastic element22so as to depress the elastic element22. That is, the gap between the inner ring211, the outer ring212and the ball213of the bearing21is eliminated by the elastic restoring force produced from the elastic element22. The blocking element23is used to press against the bearing21, particularly to the inner ring211, to prevent the bearing21from doing excessively the pre-stress of the elastic element22. The elastic fatigue of elastic element22, which shortens the lifetime of the bearing21, is thus avoided. The blocking element23presses against the inner ring211of the bearing21is only an example, and the invention is not limited to this. According to the actual design, the blocking element23is pressed against the outer ring212to achieve the purpose of preventing from doing excessively the pre-stress on the elastic element22as well.

The bearing structure20in this embodiment further includes a positioning structure27, disposed on the other side of the bearing21opposite to the pre-stress direction to press against and position the bearing21. As shown inFIG. 3, the positioning structure27is a positioning element mounted on the shaft24. The positioning element is, for example, a positioning plate as shown inFIG. 3. Alternatively, it can be a cylinder as shown inFIG. 4. In addition, the positioning structure27can be a protrusion from the shaft24or a turning part252aof the second housing252, not shown in drawing.

As shown inFIG. 5, the motor3according to a preferred embodiment of the invention includes a housing30, a rotor structure31, a stator structure32and a bearing structure33. In the embodiment, the housing30is, for example, a bearing sleeve.

In this embodiment, the motor3is implemented as a brushless motor. Of course, this is only one example of the invention, and the invention s not limited to this. The motor3is a brush motor or any type of motor as well.

The rotor structure31includes a cover311, a shaft312and a magnet313. The shaft312connects to the cover311. The magnet313is disposed around the inner sidewall of the cover311. The rotor structure31is disposed inside the housing30, and the shaft312passes through the housing30. Herein, the housing30can be a bearing sleeve (as shown inFIG. 5). Besides, according to the actual design of the motor, the housing30can be a base or a housing of the motor3(not shown in drawing). The motor3is an inner-rotor type motor.

The stator structure32includes a stator magnetic pole321disposed in the housing30. The stator magnetic pole321is formed by a coil set and disposed corresponding to the rotor structure31, particularly to the magnet313. A circuit board34is disposed in the housing30and electrically connected to the stator magnetic pole321in order to control the current direction of the stator magnetic pole321. Therefore, a rotating magnetic field is alternately produced to rotate the rotor structure31.

The bearing structure33is disposed in the housing30and fits with the shaft312. In the embodiment, the bearing structure33includes a bearing331, an elastic element332and a blocking element333.

Since the relative positions, structure features, constituent materials and functions of the components in the bearing structure33of this embodiment are the same as those in the previous embodiment, the descriptions are omitted herein.

In this embodiment, the motor3is implemented as a brushless motor, a brush motor or other types of motor. As shown inFIG. 6, the bearing structure of the invention can be used in an inner-rotor type motor5. The motor5includes a housing50, a rotor structure51, a stator structure52and a bearing structure53. The stator structure52includes a permanent magnet521, and the rotor structure51includes a shaft511and a silicon steel set512. The shaft511passes through the housing50, and the silicon steel set512is fixed to the shaft511. The silicon steel set512is wound with a coil and corresponded to the permanent magnet521. Because the primary driving structure of the inner-rotor type motor5is well-known in the prior art, the rotor structure51and the stator structure are not further described herein.

The bearing structure53is disposed inside the housing50and includes a bearing531, an elastic element532and a blocking element533. Herein, the housing50is the outer case of the inner-rotor type motor5and cooperates with the shaft511. Likewise, the relative positions, structure features, constituent materials and functions of the components in the bearing structure53of this embodiment are the same as those in the previous embodiments, the detailed descriptions are omitted.

As shown inFIG. 7, a fan4according to a preferred embodiment of the invention includes an impeller40, a housing41, a rotor structure42, a stator structure43and a bearing structure44.

Since the structure features, relative positions, constituent materials and functions of the components in the housing41, the rotor structure42, the stator structure43and the bearing structure44are the same as those in the previous embodiments, the detailed descriptions are omitted.

In this embodiment, the impeller40includes a hub401and several blades402. The blades402are disposed around the hub401. As shown inFIG. 7, the hub401is a cover421connected to the rotor structure42, and a shaft422is connected to the hub401. When the shaft422rotates, the blades402are driven to generate airflow.

In summary, the invention discloses a fan, a motor and a bearing structure thereof. The blocking element is separated from the bearing by a distance. The elastic element presses against the bearing. The blocking element has a recess for accommodating the elastic element. Therefore, when the shaft of the motor or fan rotates at a high speed and moves in an axial direction, the elastic element provides a pre-stress to the bearing. The blocking element is used to prevent the bearing from imposing excess pre-stress on the elastic element under impact. This effectively prevents the elastic element, such as a spring, from being damaged during the impact. Therefore, the invention can provide better protection for the bearing structure and lengthen the lifetime thereof.