Patent Application
20090249904
1. Field of the Invention
The present invention relates to a linear actuator, and more particularly to a transmission device, which can be radially restricted but can perform a stable axial extending/retracting movement and adjust the prestress and tension between the respective tubes by using tension adjusting device.
2. Description of the Prior Art
The existing linear actuators have a quite wide range of use and are generally driven by motors to retract and extend other mechanisms.
Referring to
The above configuration and structure can retract and extend, but it still has the following disadvantages:
First, it is unable to adjust the prestress of the respective screws during the moving process of the respective screws: since the respective screws 96, 97, 98 push the respective telescopic tubes 91, 92, 93 of the linear actuator 90, respectively. Once they become loose, they are unable to be adjusted appropriately to produce difference prestress, so that it can't meet the requirement of adjustment.
Second, complicated structure and inconvenient to assemble: the three screws 96, 97 and 98 push the respective telescopic tubes 91, 92 and 93 of the linear actuator 90, respectively, the three-segment screw assembly complicates the linear actuator 90 structure and makes its assembly inconvenient.
Third, high cost: the respective telescopic tubes 91, 92 and 93 of the above linear actuator 90 are connected to three screws 96, 97 and 98, respectively, such a structure design increases the cost of manufacturing the linear actuator 90.
Additionally, referring to
Though the above configuration and structure is extendable and retractable, it still has the following disadvantages:
First, it is likely to cause internal damage: the three telescopic tubes 81, 82 and 83 are designed in the form of a circular tube, the three telescopic tubes 81, 82 and 83 have no restricting structure, such a design is likely to cause damage to the internal structure due to the radial rotation and friction while the motor 84 drives the screw 85 to rotate.
Second, linkage is likely to cause mutual interference: with the displacement of the pulley 86 at the top of the brace rod, the screw 85 utilizes the chain to drive the telescopic tube 83 to successively link with the telescopic tube 82 and so on, furthermore, between the bottom of the telescopic tube 82 and the screw 85 is disposed a restricting structure which causes the unnecessary interference during the pulling process of the restricting structure and the chain, thus affecting the entire telescopic operation.
Though the above configuration and structure is extendable and retractable, it still has the following disadvantages:
First, it is likely to cause internal damage: the movement of the telescopic tubes 81, 82 and 83 is caused by the inner screw 85, this design still has the same disadvantages as the prior invention, the engagement of the respective tubes will become loose and loose, so that it can't meet the requirement of adjustment.
Second, it is likely to cause the structure damage during rotation: the respective tubes are designed in the form of a circular tube, the three telescopic tubes 81, 82 and 83 have no restricting structure, such a design is likely to cause damage to the internal structure due to the axial rotation and friction while the motor 84 drives the screw 85 to rotate;
Third, linkage is likely to cause mutual interference: with the displacement of the pulley 86 at the top of the brace rod, the screw 85 utilizes the chain to drive the telescopic tube 83 to successively link with the telescopic tube 82 and so on, furthermore, between the bottom of the telescopic tube 82 and the screw 85 is disposed a restricting structure which causes the unnecessary interference during the pulling process of the restricting structure and the chain, thus affecting the entire telescopic operation.
The present invention has arisen to mitigate and/or obviate the afore-described disadvantages.
The primary objective of the present invention is to provide a liner actuator which comprises a polygonal outer tube provided for insertion of an intermediate tube and an inner tube, the outer tube is disposed with a push device and at least one tension adjusting device, the push device includes a screw and a nut that are screwed with each other and restrictively disposed in the intermediate tube, and one end of the screw is disposed in the outer tube. Two pulling members are respectively disposed between the inner tube and the outer tube and between the inner tube and the intermediate tube, the respective pulling members can cooperate with the tension adjusting device to adjust the prestress of the two pulling members although there are adjustable prestress and tension between the respective tubes.
Through the cooperation of the nut and the intermediate tube, the unnecessary intervention caused by the axial movement of the respective tubes with the intermediate tube can be avoided. With the arrangement of the pulling members and the tension adjusting device, the respective tubes can perform a stable movement by the generation of the prestress of the respective tubes. By using the pulling member to adjust the clearance between the outer tube, the intermediate tube and the inner tube, the linear actuator can be radially restricted but can perform a stable axial extending/retracting movement and adjusting the clearance between the respective tubes.
The present invention will be clearer from the following description when viewed together with the accompanying drawings, which show, for purpose of illustrations only, the preferred embodiment in accordance with the present invention.
Referring to
The outer tube 10 is polygonal in cross section and is disposed with the push device 40 and the two tension adjusting devices 60A, 60B at one end thereof.
The intermediate tube 20 is polygonal in cross section and is disposed with a triangular connecting plate 21 at the end opposite to the outer tube 10, the connecting plate 21 is centrally disposed with a receiving portion 210 in the form of a round hole. The receiving portion 210 is provided for engaging with the push device 40 and a hollow cylinder-shaped push pole 22. In the inner surface of the receiving portion 210 is equidistantly disposed a plurality of elongated guiding grooves 211 extending along the extending/retracting direction of the respective tubes. The guiding grooves 211 are provided for engaging with and restricting the push device 40. The push pole 22 is disposed with an inner threaded portion 220 in one end thereof opposite to the connecting plate 21. The inner threaded portion 220 is screwed on a corresponding member in the push device 40, the other end of the push pole 22 is provided for the insertion of a three-dimensional Y-shaped pivot body 23 which is disposed with a cylindrical inserting portion 230 at one end thereof. The inserting portion 230 is inserted into one end of the push pole 22, and the other end of the pivot body 23 is a U-shaped pivot portion 231 for pivotally coupling with a first pulley 24 around which the pulling member 50A winds.
The triangular connecting plate 21 is disposed in one end thereof with a rectangular hollow portion 212 for the insertion of the pulling member 50A. The other end of the connecting plate is disposed with a slot 213. The open end of the slot 213 is pivotally coupled with a second pulley 25 around which another pulling member 50B winds.
The inner tube 30 is polygonal in cross section and is inserted into the intermediate tube 20, one end of the inner tube 30 is provided for fixing the two pulling members 50A, 50B.
The push device 40 includes a screw 41 and a nut 42 that are screwed with each other. One end of the screw 41 is pivotally coupled in the outer tube 10 and is to be driven by a motor. The nut 42 includes an outer threaded portion 420 to be screwed with the inner threaded portion 220 of the push pole 22. After the nut 42 is screwed, it will be engaged into the receiving portion 210 of the connecting plate 21. The periphery of the nut 42 is equidistantly disposed with a plurality of guiding portions 421 which extend along the extending/retracting direction of the respective tubes and are to be restricted in the guiding grooves 211 of the connecting plate 21 respectively.
The pulling member 50A winds around the first pulley 24 of the push pole 22. One end of the pulling member 50A is fixed to the tension adjusting device 60A of the outer tube 10 while the other end is fixed at the bottom of the inner tube 30.
In addition, the pulling member 50B winds around the second pulley 25 of the connecting plate 21, one end of the pulling member 50B is fixed to the tension adjusting device 60B of the outer tube 10 while the other end is fixed to one end of the inner tube 30.
The pulling members 50A, 50B can be selected from the group consisting of a belt, a chain and a steel cable.
Referring to
Additionally,
With the above structures, the present invention can offer the following functions:
1. stabilizing and restricting retracting/extending movement: the outer tube 10, intermediate tube 20 and the inner tube 30 are all the polygonal tube-shaped structures, and the outer tube 10 is provided for the insertion of the intermediate tube 20 and the inner tube 30, by such a polygonal tube-shaped structure design, the outer tube 10, the intermediate tube 20 and the inner tube 3 can be radially restricted but can perform a stable axial extending/retracting movement.
2. convenience of production, check and assembly: the arrangement of the nut 42 and the push pole 22 of the intermediate tube 20 provides convenience of production, check and assembly, which also reduces the interference of the respective tubes, lowers the noise and smoothes the extending and retracting movement during the extension and retraction of the outer tube 10, the intermediate tube 20 and the inner tube 30.
3. high safety: the inner tube 30 can be prevented from dropping down to impact the intermediate tube 20 due to damage of one of the pulling member 50A or the pulling member 50B, thus achieve the high safety.
4. adjusting the clearance between the respective tubes: the tension adjusting devices 60A, 60B can adjust the clearance between the outer tube 10, the intermediate tube 20 and the inner tube 30 by the pulling members 50A, 50B so as to strain the condition of the telescope action of the linear actuator.
While we have shown and described various embodiments in accordance with the present invention, it is clear to those skilled in the art that further embodiments may be made without departing from the scope of the present invention.
