Electric Motor Capable of Dissipating Heat Therein

An electric motor generally includes a housing, a cover, and a cooling fan. The cover defines multiple inlet holes and is formed integrally with an air collecting ring around the inlet holes so as to provide an airflow path for allowing a central portion of the air current generated by the cooling fan to enter the housing. The housing defines a plurality of communication holes and a plurality of outlet holes for allowing the air which has entered the housing to flow thereout. In addition, the present invention provides another path so that an outer portion of the air current can flow along the outer surface of the housing to reduce the temperature of the housing. Through multiple paths for heat dissipation, heat is not easy to accumulate in the housing of the electric motor.

(a) TECHNICAL FIELD OF THE INVENTION

The present invention relates to an electric motor capable of dissipating heat therein and, more particularly, to an electric motor which can effectively dissipate the heat generated in its housing through multiple paths, so that heat is not easy to accumulate in the electric motor's housing; thus, maximum power output of the electric motor can be achieved, and the performance and service life of the electric motor can be increased.

(b) DESCRIPTION OF THE PRIOR ART

In today's industry, motors are one of commonly used devices for providing mechanical power. However, while a motor is running, heat is easy to accumulate in the motor's housing. If the heat is not timely dissipated, the magnetic field provided by the magnets in the motor's housing will decrease, so that the performance of the motor can be gradually reduced. Besides, when the temperature in the motor rises to a certain level, the coils or enamel wires in the motor can be damaged, and this may cause a short circuit, and thus the motor may burn out. For preventing such a problem, a motor is usually provided with a cooling fan. However, the air current generated by the cooling fan of the motor can only flow along the outer surface of the motor's housing, but cannot flow into the interior of the motor, and thus the capacity of dissipating the heat generated in the motor is limited. The problem of heat accumulation in the motor's housing has not yet been solved completely.

SUMMARY OF THE INVENTION

One object of the present invention is to provide an electric motor, which can effectively dissipate the heat generated in its housing through multiple paths.

According to one feature of the present invention, the electric motor generally includes a housing, a cover, a rotating shaft, and a cooling fan. The housing has a surrounding wall defining therein an inner space with a front opening and has a rear closure wall opposite to the front opening. The rear closure wall defines a central hole and a plurality of outlet holes. The cover, which closes the front opening of the housing, has a central hub defining a central hole and has a peripheral portion integrally formed around the central hub. The peripheral portion of the cover is formed integrally with an air collecting ring around the central hub and defines a plurality of inlet holes between the air collecting ring and the central hub, whereby a central portion of a whirling, ongoing air current generated by the cooling fan can flow through the space between the air collecting ring and the central hub of the cover and then flow through the inlet holes of the cover to enter the inner space of the housing and finally flow out of the housing via the outlet holes for dissipating the heat generated in the housing.

According to another feature of the present invention, the housing defines at least one communication hole at its surrounding wall, so that the air current having entered the inner space of the housing may flow out of the housing via the communication hole in addition to the outlet holes of the housing to take away the heat generated in the housing.

According to one advantage of the present invention, the electric motor can be used in a high-temperature environment without being damaged. In a test, the electric motor was continuously operated in a closed space of 70 degrees C. for a long time without burning out.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Since the structure and operational principles of an electric motor have been known widely, a detailed description for the constituent parts thereof is not provided in the following paragraphs.

Referring first toFIGS. 1 through 3, an electric motor according to one embodiment of the present invention is shown, which generally includes a cylindrical housing1, a cover2, a rotating shaft8, and a cooling fan4. The housing1has a surrounding wall, which defines therein an inner space14with a front opening12, and has a rear closure wall11opposite to the front opening12. The rear closure wall11defines a central hole, in which a bearing may be mounted, and a plurality of outlet holes13around the central hole. The surrounding wall of the housing1defines a plurality of communication holes10, through which the air within the housing1may flow into ambient environment. Furthermore, a rotor5, coils6and magnets7, which are necessary elements for an electric motor, are provided in the inner space14of the housing1(seeFIG. 7). The rotating shaft8is mounted across the inner space14of the housing1, wherein the rotating shaft8has a first end80which is inserted through the central hole of the rear closure wall11for connecting with a transmission mechanism (not shown) for providing necessary mechanical power. The rotating shaft8has a second end89which is inserted out of the front opening12of the housing1to be fitted with the cooling fan4, as will be further illustrated below. A magnetically permeable sleeve3, which can be made of metal, is closely fitted around the outer surface of the surrounding wall of the housing1, to increase the performance of the electric motor.

FIGS. 4 and 5show the cover2used in the electric motor of the present invention, wherein the cover2has a central hub20, which has a conical surface22and defines a central hole21, and a peripheral portion integrally formed around the central hub20. The central hub20tapers off from its round base which is formed integrally with the peripheral portion of the cover2; namely, the diameter of a cross section of the central hub20is gradually reduced as compared to the round base of the central hub20. The peripheral portion of the cover2is provided with an air collecting ring24around the central hub20, and defines a plurality of inlet holes23between the air collecting ring24and the central hub20. The air collecting ring24can be formed integrally with the peripheral portion of the cover2. Furthermore, the cover2is provided with two mounting tubes281,282at an inner surface of the peripheral portion thereof, and defines two through holes271,272(seeFIG. 5). When the cover2is installed to the housing1, two electrical terminal blades81,82provided in the housing1can be inserted through the two through holes271,272of the cover2, while two fixing dowel rods83,84provided in the housing1can be inserted into the two mounting tubes281,282of the cover2, so that the cover2closes the front opening12of the housing1, and electrical connection for the electrical motor is facilitated. While the cover2is being installed to the housing1, the second end89of the rotating shaft8can be inserted through the central hole21of the central hub20of the cover2, wherein a bearing (not shown) may be provided in the central hub20of the cover2and fitted with the second end89of the rotating shaft8.

As shown inFIG. 1, the cooling fan4defines a central hole40, into which the second end89of the rotating shaft8extending out of the central hole21of the cover2can be fitted, so that the cooling fan4is attached to and rotated together with the rotating shaft8.

FIGS. 2 and 3show an assembled electric motor, which are assembled from the housing1, the cover2, and the cooling fan4. When the electric motor is started, the cooling fan4can be rotated together with the rotating shaft8to generate a whirling, ongoing air current towards the cover2, so that the air at the right side of the cooling fan4can be forced to flow into the left side of the cooling fan4(seeFIG. 6). In particular, the air current can enter the inner space14of the housing1easily, and the heat generated in the housing1can be dissipated effectively through multiple paths (seeFIGS. 6 through 9). A central portion of the air current generated by the cooling fan4can be guided by the air collecting ring24of the cover2and the conical surface22of the central hub20to smoothly flow through the space between the air collecting ring24and the conical surface22, and then to pass through the associated inlet holes23to enter the inner space14of the housing1, as indicated by the airflow path (A) shown inFIGS. 7 and 8. In addition, an outer portion of the air current, which is outside the area of the air collecting ring24of the cover2, may flow along the outer surface of the housing1or the sleeve3(seeFIG. 7), so that the housing1can be effectively cooled down to facilitate dissipation of the heat generated in the housing1. In this embodiment, the air current which has entered the inner space14of the housing1can flow out of the housing1via the outlet holes13and the communication holes10(seeFIGS. 7 and 9), so that the heat generated in the housing1can be taken away with the leaving air current. The multiple airflow paths (A), (B) allow the heat generated in the housing1to dissipate more effectively, so that the electric motor can be prevented from burning out.

As a summary, the inlet holes23of the cover2, with the assistance of the air collecting ring24, allows the electric motor of the present invention to provide an airflow path (A) via which a central portion of the air current generated by the cooling fan4enters the inner space14of the housing1to dissipate the heat generated in the housing1. In addition, the present invention provides another airflow path (B) via which an outer portion of the air current, which does not enter the inner space of the housing, flows along the outer surface of the housing1to lower the temperature of the housing1and thus to increase the capacity of dissipating the heat generated in the housing1. Through multiple paths for heat dissipation, heat is not easy to accumulate in the housing1of the electric motor; therefore, maximum power output of the electric motor can be achieved, and thus the performance and service life of the electric motor can be increased. Even though the electric motor is operated in a high-temperature environment, it will not burn out. These features render the electric motor of the present invention useful and inventive.

Although the present invention has been described with a certain degree of particularity, it is understood that the present disclosure is made by way of example only and the combination and arrangement of parts may be resorted to without departing from the spirit and scope of the invention hereinafter claimed.