Patent Application
20140000447
1. Field of the Invention
The present invention relates to a pneumatic motor, more particularly to a rotor of a pneumatic motor.
2. Description of the Prior Art
A pneumatic motor is driven by compressed air to provide torque output to drive other tools to rotate further. A conventional pneumatic motor usually has adjustment mechanism to increase power output. For example, a pneumatic motor disclosed in patent TW 1259865 has two sets of inlet and outlet, and the motor also includes a control valve assembly to alternatively open or close the inlet and the outlet. Thus, power stoke of compressed air in the motor is increased, and larger torque output is provided.
However, conventional pneumatic motors don't have sufficient stability of power output. Please refer to a pneumatic motor disclosed in patent TW M388576, the rotor disposes only three blades. When the rotor is driven to rotate by compressed air, entering and releasing of compressed air result that torque the rotor acquires varies to reduce stability, and vibration of the motor is increased. Thus, another conventional pneumatic motor has six blades to provide stabler and larger torque output.
When more blades are employed in a pneumatic motor, more slots should be formed on the rotor, and strength of the rotor is thereby decreased. Hence, number of blades in a pneumatic motor is limited, and applying more blades on a pneumatic motor for providing stabler torque output becomes unworkable in practice.
Moreover, applying more blades on a pneumatic motor can help increase contact with compressed air to provide larger torque output theoretically. However, more blades results more friction with the inner wall of cylinder when the axle rotates. Thus, torque output is not promoted distinctly, and rpm of the rotor is decreased under a tolerant minimum of 10%.
The present invention is, therefore, arisen to obviate or at least mitigate the above mentioned disadvantages.
The main object of the present invention is to provide a pneumatic motor which is able to provide stabler and larger torque output.
The other object of the present invention is to provide a pneumatic motor with more blades which retains enough strength of rotor and is able to provide larger torque output.
To achieve the above and other objects, a pneumatic motor of the present invention includes a cylinder, a rotor, and a limitation mechanism.
The cylinder encloses a receiving room, an inlet, and an outlet, wherein the inlet and the outlet communicate with the receiving room. The cylinder has an inner wall defined on a circumference of the receiving room.
The rotor includes an axle and a plurality of main blades. The axle defines an axial direction and a radial direction. The axle is rotatably disposed in the receiving room deviating from a center of the receiving room. The axle has an outer surface. The axle forms a plurality of main sliding slots which are radially recessed, and the main sliding slots are annularly arranged around the outer surface of the axle. Each main blade is disposed in one of the main sliding slot and is able to slide radially. Thus, when the axle rotates, each main blade is able to rotate simultaneously and touch the inner wall of the cylinder. The axle and the main blades partition the receiving room into a plurality of air chamber to enable compressed air to drive the rotor to rotate and to be released from the outlet.
Furthermore, the rotor also includes a plurality of secondary blades, and the axle forms a plurality of secondary sliding slots which are radially recessed. The secondary sliding slots are annularly arranged around the outer surface. Each secondary sliding slot has a smaller depth than a depth of each main sliding slot, and each secondary sliding slot has a smaller length than a length of each main sliding slot. Each secondary blade is slidably disposed in one of the secondary sliding slot, and the limitation mechanism is able to prevent the secondary blade from leaving the secondary sliding slot. When the axle rotates, each secondary blade rotates simultaneously. Each secondary blade is able to slide radially and to partially protrude outside of the outer surface. Thus, each secondary blade is able to touch the inner wall when located at angles equal to or smaller than a specific angle from the inlet, and each secondary blade is away from the inner wall when located at angles larger than a specific angle from the inlet.
Therefore, the secondary blades help promote torque output, and friction between the rotor and the cylinder is decreased due to the secondary blades which are away from the inner wall of the cylinder when the secondary blades are located at angles larger than the specific angle from the inlet. Thus, efficiency is promoted, and the revolution speed of the rotor is still in a tolerant range.
The present invention will become more obvious from the following description when taken in connection with the accompanying drawings, which show, for purpose of illustrations only, the preferred embodiment(s) in accordance with the present invention.
Please refer to
The cylinder 1 encloses a receiving room 11, an inlet 12, and an outlet 12, wherein the inlet 12 and the outlet 13 communicate with the receiving room 11. The cylinder 1 has an inner wall defined on a circumference of the receiving room 11. Compressed air is able to enter the receiving room 11 via the inlet 12 and then to be discharged via the outlet 13. In other possible embodiment, the cylinder 1 can form a plurality of inlets and outlets, and path of compressed air is able to be changed by a valve. Thus, operating direction of the motor can be changed.
The rotor 2 includes an axle 21 and a plurality of main blades 22. An axial direction and a radial direction are defined by the axle 21. The axle 21 is rotatably disposed in the receiving room 11 deviating from a center of the receiving room 11. In other word, a center of the axle 21 is separated from the center of the receiving room 11. The axle 21 has an outer surface 211 and forms a plurality of main sliding slots 212 which are recessed radially. The main sliding slots 212 are annularly arranged around the outer surface 211. Each main blade 22 is disposed in one of the main sliding slot 212 and is able to slide radially. Thereby, when the axle 21 rotates, each main blade 22 is able to rotate simultaneously and to touch the inner wall radially. The axle 21 and the main blades 22 partition the receiving room 11 into a plurality of air chambers. Thus, due to the air chambers, compressed air is able to enter the receiving room 11 via the inlet 12 to drive the rotor 2 to rotate, and compressed air is able to be discharged via the outlet 13.
The rotor 2 further includes a plurality of secondary blades 23 which are shorter than the main blades. The axle 21 forms a plurality of secondary sliding slots 213 which are radially recessed. The secondary sliding slots 213 are annularly arranged around the outer surface 211, and a depth of each secondary sliding slot 213 is smaller than a depth of each main sliding slot 212. More preferably, a number of the secondary sliding slots 213 is equal to a number of the main sliding slots 212. Besides, the secondary sliding slots 213 are arranged alternatively. In other words, each secondary sliding slot 213 is located between two of the main sliding slot 212. Each secondary blade 23 is slidably disposed in one of the secondary sliding slots 213. Each secondary blade 23 is able to slide radially and to partially protrude outside of the outer surface 211.
The limitation mechanism is adapted for retain each secondary blade 23 to corresponding secondary sliding slot 213 when the axle 21 rotates. Also, due to the limitation mechanism, each secondary blade 23 is able to touch the inner wall of the cylinder when located at angles equal to or smaller than a specific angle from the inlet, as shown in
Furthermore, the limitation mechanism includes a plurality of ribs 31 and a plurality of limitation slots 32. The ribs 31 are formed on two opposite sides of each secondary blade 23 respectively, and the limitation slots 32 are formed on two opposite sides of each secondary sliding slot 213 respectively. The ribs 31 are slidably disposed in the limitation slots 32. As such, the ribs 31 and the secondary blades 23 are restricted in the limitation slots 32 and the secondary sliding slots 213. More preferably, the ribs 31, the secondary blades 23, the limitation slots 32, and the secondary sliding slots 213 are equal in axial length.
Please refer to
Moreover, the secondary blades 23 are able to abut against the inner wall of the cylinder when located at angles equal to or smaller than the specific angle, so that torque output can be promoted. Besides, the secondary blades 23 leave the inner wall of the cylinder when located at angles larger than the specific angle, so that friction between the rotor and the inner wall of the cylinder is reduced. Thus, under the premise that the revolution speed which the rotor loses is under 10%, torque output of the cylinder is promoted significantly.
On the other hand, the applicant had some efficiency tests by applying the present invention to pneumatic tools which are manufactured by Hyphone Machine Industry CO., LTD. The following tables show models of tools and the acquired data.
The previous tables show test data of an air impact wrench model HY-2360 and a grinder model HY-1742 which are manufactured by Hyphone Machine Industry CO., LTD. Referring to the data, revolution speed of the present invention is lower than a conventional pneumatic motor but still in a tolerant range of 10%. However, larger torque output is provided. The revolution speed is probably lowered by mass of the rotor or moment of inertia, and the revolution speed is able to be promoted by reducing mass of elements of the rotor or moment of inertia of the rotor. Thus, referring to the test data, the pneumatic motor is able to provide larger output absolutely.
In addition, the secondary sliding slots may results that too many sliding slots should be formed on the axle, so that strength of structure of the axle may be reduced. Thus, bottoms of the main sliding slots and the secondary sliding slots may collapse. To prevent the previous situation, the secondary sliding slots of the present invention have smaller depths than depths of the main sliding slots, so that bottoms of main sliding slots and secondary sliding slots can dodge from each other. Strength of structure of the axle is thereby retained.
Please refer to
In conclusion, the shorter secondary blades are able to partition the receiving room into a plurality of secondary air chambers for filled with compressed air continuously, so that the axle can be driven uniformly. In addition, the secondary blades help contribute the torque output. Also, the secondary blades don't touch the inner wall of the cylinder when located at angles larger than the specific angle from the inlet, so that the friction between the rotor and the cylinder is reduced.
