The invention relates to actuators, particularly to an actuator with a safety mechanism.
An actuator primarily uses a motor, a worm and a worm gear to drive a guiding threaded rod to rotate. And the guiding threaded rod drives a retractable tube connected thereto to make a stretching or retracting act. Because such an actuator is simpler and more convenient than a hydraulic cylinder or pneumatic cylinder in structure and installation, it has been widely applied in sickbeds and electric chairs, doors and windows, or other circumstances requiring reciprocation.
Most existing actuators are arranged with a front limit switch and a rear limit switch in a moving path of a nut of the retractable tube for being touched by the nut during the moving of the nut by the guiding threaded rod. As a result, the retractable tube can be effectively controlled to stretch or retract.
However, when the existing actuator is applied in electric chairs or windows, because the motor can be stopped only while the nut is touching one of the two limit switches which are located at two opposite ends of the retractable tube, if a user or child accidentally puts his or her hand in the machine while the nut is moving to a middle position of the travel, there is no safety mechanism which can stop the motor. As a result, pinching injuries will occur. This problem should be overcome.
An object of the invention is to provide an actuator with a safety mechanism, which can accomplish an anti-pinch effect by means of movability of the transmission to increase safety of the product in use.
To accomplish the above object, the actuator with a safety mechanism of the invention includes a gear box, a motor, a driven gear, a transmission, a retractable tube and a push switch. The motor is connected to the gear box. The driven gear is received in the gear box and driven by the motor. The transmission is partly received in the gear box and partly projects over the gear box. The transmission has a guiding threaded rod and a touch element mounted around the guiding threaded rod. An end of the guiding threaded rod penetratingly connects the driven gear and is movably supported in the gear box with the touch element. The retractable tube is arranged at a side of the gear box and threadedly connects the guiding threaded rod to be driven. The push switch is electrically connected to the motor and is arranged in a moving path of the touch element. When the retractable tube is limited during moving, the transmission will linearly move toward a direction of the retractable tube and the motor is stopped operating by touching the push switch with the touch element.
The invention also has the following advantages. By an arrangement of an elastic element, the bearing and the guiding threaded rod can be restored to their original positions. When the actuator of the invention is applied in an electric window, the window can be closed more tightly by the pressing block pressing the touch switch and stopping the motor.
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The gear box 10 is a cuboidal body made of a metal and includes a lower case 11 and an upper case 12. A gear room 111, a bearing room 112 and a spring room 113 are formed in the lower case in sequence. The upper case 12 correspondingly covers the lower case 11. The inside of the upper case 12 is also formed with a structure corresponding to and the same as the gear room 111, the bearing room 112 and the spring room 113.
The motor 20 is arranged at a side of the lower case 11 of the gear box 10 and is fixed on the lower case 11 by fasteners such as screws. In the embodiment, the power of the motor 20 is transferred through a transmission gear 111 entering the gear room 111.
The driven gear 30 is received in the gear room 111 and connected to the front and the rear of the driven gear 30 though two supporting elements 31. Thus they all are conjointly supported in the gear box 10. The driven gear 30 has an outer gear 301 meshing with the transmission gear 21 so as to be able to be driven by the motor 20 to rotate. The center of the driven gear 30 is formed with a though hole 302. An inner wall of the through hole 302 is formed with inner embedding troughs 303.
A part of the transmission 40 is arranged in the gear box 10 and the other part of the transmission 40 projects over the gear box 10. The transmission 40 includes a guiding threaded rod 41 and a touch element 42. The guiding threaded rod 41 includes a thread section 411, a round shaft section 412 extending from the thread section 411, a limiting section 413 extending from the round shaft section 412 and a screw section 414 extending from the limiting section 413. The touch element 42 is connected around the round shaft section 412.
The guiding threaded rod 41 is movably connected to the driven gear 30 through a shaft connector 415. A shape of an inner hole of the shaft connector 415 corresponds to a periphery of the limiting section 413 to be a polygon for conjointly rotating. A plurality of ribs 416 engaging with the inner embedding troughs 303 are formed on a periphery of the shaft connector 415 so as to make the guiding threaded rod 41 move forward or rearward axially only along the through hole 302 of the driven gear 30. The shaft connector 415 is connected after the limiting section 413. The shaft connector 415 is connected to the guiding threaded rod 41 to be an integral by screwing a nut 417 onto the screw section 414.
Further, the transmission 40 includes a bearing 43 connected to the touch element 42 and supported in the bearing room 43 of the gear box 10. An axial length of the bearing room 112 is great than a width of the bearing 43 to allow the bearing 43 to make movably linear displacement in the bearing room 112.
Further, the transmission 40 includes an elastic element 44 around the guiding threaded rod 41 and in the spring room 113. Two ends of the elastic element 44 are pinched between an inner wall of the gear box 10 and an end of the touch element 42.
Further, the touch element 42 of the embodiment includes a shaft sleeve 421 and a connecting ring 425. The shaft sleeve 421 is put around the round shaft section 412 of the guiding threaded rod 41 and rotates with the guiding threaded rod 41. An end of the shaft sleeve 421 is formed with a groove 4211. The connecting ring 425 is of a C-shape and put around the groove 4211 to be positioned. The connecting ring 425 does not rotate with the shaft sleeve 421 and the guiding threaded rod 41. A pressing block 4251 is extended from a middle of the connecting ring 425. A bottom right position of the pressing block 4251 is formed with a slant 4252.
The retractable tube 50 is arranged at a side of the gear box 10. An end of the retractable tube 50 is firmly connected with a nut 51 by which the retractable tube 50 is connected to the guiding threaded rod 41 to rotate conjointly.
The push switch 60 is electrically connected to the motor 20 though a wire (not shown) and is arranged in a moving path of the touch element 42.
Additionally, the actuator with a safety mechanism of the invention further includes an outer tube 70, a limit switch 71 and a front cover 72. The outer tube 70 completely covers the gear box 10, retractable tube 50, push switch 60 and limit switch 71 and formed on a side of the motor 20. The limit switch 71 is located in a moving path of the nut 51. The front cover 72 covers the front of the outer tube 70. An end of the retractable tube 50 projects over the outer tube 70 through the front cover 72.
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It will be appreciated by persons skilled in the art that the above embodiments have been described by way of example only and not in any limitative sense, and that various alterations and modifications are possible without departure from the scope of the invention as defined by the appended claims.
Number | Date | Country | Kind |
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106212050 U | Aug 2017 | TW | national |
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