ROTARY PADDLE LEVEL SWITCH |
|||||||
申请号 | US14031249 | 申请日 | 2013-09-19 | 公开(公告)号 | US20150077954A1 | 公开(公告)日 | 2015-03-19 |
申请人 | Finetek Co., Ltd.; | 发明人 | Chih-Wen Wang; Ching-Jui Chen; Cheng-Tao Lee; Ting-Kuo Wu; Chao-Kai Cheng; | ||||
摘要 | A rotary paddle level switch has a housing, a driving unit, two switches, a resilient member, a clutch, a transmission shaft, and a propeller. A resilient clip of the clutch holds a non-circular actuation section of the transmission shaft. When the driving unit drives the clutch to rotate, the transmission shaft and the propeller are driven by the clutch. When the propeller is rapidly rotated by suddenly exerting an excessively large external force thereon, as the resilient clip holds the transmission shaft by elastic force, the fast rotating transmission shaft removes itself from the holding of the resilient clip and is rotated without driving the resilient clip to rotate, thereby avoiding the transmission of the external force and damage to the driving unit. As the clutch just needs a clutch stand and a resilient clip to achieve the foregoing function, the level switch is structurally simple and relatively inexpensive. | ||||||
权利要求 | What is claimed is: |
||||||
说明书全文 | 1. Field of the Invention The present invention relates to a level switch, and more particularly to a rotary paddle level switch applied to detect material level of warehouse. 2. Description of the Related Art Level switches are applicable to material management of warehouse, and serve to monitor the availability of material in warehouse or to detect the level of material stored in warehouse. The material in a warehouse may be any kind of material with a constant specific weight, such as, animal feed, grain, peanut, malt, clay, sand, limestone, rock, sawdust, lumber, metal, rubber, resin, plastic pellet, regrinding plastic, coal, cast material, and the like. Level switches can be classified as rotary paddle level switches, vibrating fork level switches, and capacitive level switches according to design concepts of the level switches. A conventional rotary paddle level switch has a housing, a driving unit, a first switch, a second switch, a torque spring, a transmission shaft, and a propeller. The driving unit is pivotally mounted inside the housing, and has a pressing rod mounted away an axial direction and extending in an eccentric direction. The two switches are mounted inside the housing. One end of the torque spring abuts against an inner wall of the housing, and the other end of the torque spring pushes against the pressing rod such that the pressing rod abuts against the first switch. The transmission shaft is driven by the driving unit, and protrudes beyond the housing. The propeller is mounted on an external end of the transmission shaft. When the conventional rotary paddle level switch is mounted in a warehouse and is operated, the driving unit drives the transmission shaft to rotate the propeller. When the level of a stored material rises up to reach the propeller, the propeller and the transmission shaft stop rotating because of the resistance caused by the material, and the driving unit compresses the torque spring to reversely rotate the transmission shaft. The pressing rod of the driving unit then departs from the first switch and abuts against the second switch instead. The driving unit stops rotating the transmission shaft after the pressing rod no longer abuts against the first switch. The second switch signals that the material has been accumulated to a designated level after being abutted, so as to achieve the objective of monitoring the level of a material stored in a warehouse. However, the conventional rotary paddle level switch has the following shortcomings. Firstly, during the course of dropping a material in a warehouse, the material may hit the propeller from a specific angle to abruptly rotate the propeller at a high speed. Rotating at a high speed, the parts of the driving unit, such as transmission gears, are prone to damage. A clutch is therefore mounted between the transmission shaft and the driving unit. When the propeller and the transmission shaft are subject to an excessively large external force, the clutch disconnects the transmission shaft from the driving unit to prevent the driving unit from being damaged. However, the conventional clutch is structurally complicated, and the production cost of the clutch is relatively high. Secondly, when the propeller hits the accumulated material and generates a resistance force, the resistance force generates a torque that is indirectly exerted on the torque spring. However, the sensitivity and accuracy of the torque spring are not as satisfactory as expected, early or late deactivation of the driving unit. An objective of the present invention is to provide a rotary paddle level switch being structurally simple and less costly. To achieve the foregoing objective, the A rotary paddle level switch has a housing, a circuit board, a first switch, a second switch, a resilient member, a clutch, and a propeller. The circuit board is mounted inside the housing. The driving unit is rotatably mounted inside the housing, is electrically connected to the circuit board, and has a pressing member and an output member. The pressing member and the output member are not co-axial. The pressing member is mounted on a bottom of the driving unit. The output member is rotatably mounted in the driving unit and protrudes downwards. The first switch is mounted inside the housing and is electrically connected to the circuit board. The second switch is mounted inside the housing, is electrically connected to the circuit board, and is spaced apart from the first switch by a gap. The resilient member is mounted inside the housing, and pulls the driving unit for the pressing member of the driving unit to abut against the first switch. The transmission shaft is mounted in the housing, has an actuation section formed on a top end of the transmission shaft, and has a non-circular section. A bottom end of the transmission shaft protrudes downward beyond the housing. The clutch is mounted inside the housing, is connected between the driving unit and the transmission shaft, is driven by the driving unit to rotate, and has a clutch stand and a resilient clip. The clutch stand is non-relatively rotationally coupled to the output member of the driving unit, and sleeves the actuation section of the transmission shaft. The resilient clip is mounted inside the clutch stand, clips the actuation section of the transmission shaft, and is selectively opened by the actuation section. The propeller is mounted on the transmission shaft, and is located outside the housing. The present invention is advantageous in that the resilient clip of the clutch holds the non-circular actuation section of the transmission shaft and the clutch is rotatable with the transmission shaft and the propeller when the driving unit drives the clutch to rotate during a regular operating condition, and the transmission removes itself from the holding of resilient clip and is rotated alone without driving the resilient clip to rotate when the propeller is suddenly subject to an excessively large external force and all of a sudden the external force drives the transmission shaft to rapidly rotate, so as to avoid the transmission of the external force and damage to the driving unit. The clutch only has a clutch stand and a resilient clip to achieve the foregoing effectiveness, and is therefore structurally simple and relatively cost-effective. Additionally, the resilient member is a tension spring, which has higher sensitivity and torque accuracy. Accordingly, the resilient spring allows the driving unit to accurately resist the torque and moves the pressing member at a right timing. The rotary paddle level switch further has a light-emitting unit connected to the housing and electrically connected to the circuit board. When a material is accumulated up to a designated level, the second switch is triggered, and the light-emitting unit simultaneously emits light to be visible to users. Other objectives, advantages and novel features of the invention will become more apparent from the following detailed description when taken in conjunction with the accompanying drawings. With reference to With reference to The circuit board 14 is mounted inside the housing 10, is mounted on a bottom of the support board 13, and a second track hole 141. The second track hole 141 is formed through the support board 13, and is a curved hole. The second track hole 141 is located underneath the first track hole 131 of the support board 13. With reference to With reference to With reference to With reference to With reference to The transmission shaft 70 is mounted in the bottom base 11 of the housing 10 and is connected with the clutch 60, and has an actuation section 71. The actuation section 71 is formed on a top end of the transmission shaft 70, and has a non-circular section. In the present embodiment, the actuation section 71 has two abutment surfaces 711. The two abutment surfaces 711 are radially and oppositely formed in a periphery of the actuation section 71. The actuation section 71 is mounted through the transmission recess 632 of the clutch stand 63 of the clutch 60, and the two abutment surfaces 711 of the actuation section 71 are respectively held by the two clipping portions 642 of the resilient clip 64. A bottom end of the transmission shaft 70 protrudes downward beyond the housing 10. With reference to When in use, the rotary paddle level switch is fixed in a warehouse, and is electrically connected to a control system. With reference to When the material is piled up and blocks the rotation of the propeller 80, the material becomes a resistance preventing the propeller 80 and the transmission shaft 80 from rotating. The higher the level of the stored material and the larger the resulting contact area with the propeller 80, the more the resistance force is. Finally, the transmission shaft 70 is unable to rotate as a result of the escalating resistance force. With reference to The foregoing description associates with regular operation of the rotary paddle level switch. With reference to To achieve the foregoing effectiveness with just the clutch stand 63 and the resilient clip 64, the clutch 60 is advantageous in simple structure and inexpensive cost. Even though numerous characteristics and advantages of the present invention have been set forth in the foregoing description, together with details of the structure and function of the invention, the disclosure is illustrative only. Changes may be made in detail, especially in matters of shape, size, and arrangement of parts within the principles of the invention to the full extent indicated by the broad general meaning of the terms in which the appended claims are expressed. |