Abstract:
A linear travel structure of an electrical operating device includes a body, a substrate, a cover, a first transmission assembly, a second transmission assembly, and a third transmission assembly. The body receives the substrate to mount thereto so as to enclose and define a first receiving space. The cover is mounted to the body and, together with the substrate, encloses and defines a second receiving space. The substrate includes an electrical machine mounted thereto and received in the second receiving space. The first transmission assembly, the second transmission assembly, and the third transmission assembly are all received in the first receiving space. The electrical machine is connected in cascade with the first, second, and third transmission assemblies for operation therewith. With such a multiple-staged transmission arrangement, advantages including high transmission efficiency, high bearing capacity, high speed ratio, and small volume, can be achieved over the conventional devices.

Description:
(a) TECHNICAL FIELD OF THE INVENTION 
     The present invention generally relates to an electrical operating device that has multiple stages and utilizes planetary gears, and more particularly to a linear travel structure of an electrical operating device that features high transmission efficiency, high bearing capacity, high speed ratio, and small volume. 
     (b) DESCRIPTION OF THE PRIOR ART 
     A valve driver, which is also referred to as an actuator or an actuation mechanism, is a component commonly used in the field of automatic control for performing automatic operations, controlling or adjusting switches, and replacing manual operations and is classified as several types, according to the structure and operation thereof, such as linear travel, angular travel, and rotary type, of which the driving power can be pneumatic, hydraulic, electrical, or electrical/hydraulic. The valve driver can replace humans to directly carry out operations in risk areas and can greatly improve manufacturing performance due to control preciseness and operation efficiency. 
     Among the valve drivers, the kind that is operated with electrical power has unmatchable advantages over the other kinds. Among all of the kinds, the kind that is operated with electricity has been developed fastest and has the characteristics of easy acquirement of energy resources, fast response, high speed of signal transmission, remote transmission of signal, and being operable with digital devices. 
     The conventional valve drivers generally comprise a worm and worm gear arrangement to work with a clutch to realize transmission of power. Such an arrangement suffers the following disadvantages in the use thereof: 
     (1) The worm and worm gear arrangement requires a small lead angle for complete self-locking and this leads to an increased contact area and thus relatively poor efficiency. 
     (2) The worm and worm gear arrangement has a low efficiency of transmission and thus, severe wear may caused in the operation thereof (so that the clearance is gradually increased with the use thereof), whereby when the worm and the worm gear are set in engagement with each other for transmission, the relative slipping speed between the mated components is great, leading to increased wear and abrasion, reduced efficiency, and increased axial force of the worm. 
     SUMMARY OF THE INVENTION 
     The primary object of the present invention is that an electrical machine is combined with a first transmission assembly, a second transmission assembly, and a third transmission assembly to achieve multiple-staged transmission whereby, with such an arrangement, the problems of poor transmission efficiency and severe wear occurring in the prior art devices can be overcome to achieve the advantages of high transmission efficiency, high bearing capacity, high speed ratio, and small volume. 
     The present invention provides a linear travel structure of an electrical operating device, which comprises, structurally, a body. A substrate is mounted to one side of the body so that the substrate and the body enclose and define a first receiving space. A cover is mounted to one side of the body in such a way that the cover and the substrate enclose and define a second receiving space. The second receiving space receives therein an electrical machine. The first receiving space receives therein a first transmission assembly, a second transmission assembly, and a third transmission assembly. The electrical machine is mounted to a surface of the substrate and is operatively coupled to the first transmission assembly. The second transmission assembly is operatively coupled to the first transmission assembly. The third transmission assembly is operatively coupled to the second transmission assembly. 
     With such an arrangement, when put into operation, the electrical machine drives the first transmission assembly to rotate in synchronization therewith and, at the same time, the second transmission assembly and the third transmission assembly are also driven to rotate so as to achieve multiple-staged transmission. Due to the adoption of the NWG mechanism, the transmission efficiency can be greatly improved and at the same time, the problem of excessive wear can also be handled. Further, the interior space of the second receiving space can be fully used to greatly reduce the overall volume thereby achieving the advantages of high transmission efficiency, high bearing capacity, high speed ratio, and small volume. 
     The foregoing objectives and summary provide only a brief introduction to the present invention. To fully appreciate these and other objects of the present invention as well as the invention itself, all of which will become apparent to those skilled in the art, the following detailed description of the invention and the claims should be read in conjunction with the accompanying drawings. Throughout the specification and drawings identical reference numerals refer to identical or similar parts. 
     Many other advantages and features of the present invention will become manifest to those versed in the art upon making reference to the detailed description and the accompanying sheets of drawings in which a preferred structural embodiment incorporating the principles of the present invention is shown by way of illustrative example. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a longitudinal sectional view of a preferred embodiment of the present invention. 
         FIG. 2  is a lateral sectional view of the preferred embodiment of the present invention. 
         FIG. 3  is a longitudinal sectional view of a third transmission component of the preferred embodiment of the present invention. 
         FIG. 4  is a lateral sectional view of the third transmission component of the preferred embodiment of the present invention. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     The following descriptions are exemplary embodiments only, and are not intended to limit the scope, applicability or configuration of the invention in any way. Rather, the following description provides a convenient illustration for implementing exemplary embodiments of the invention. Various changes to the described embodiments may be made in the function and arrangement of the elements described without departing from the scope of the invention as set forth in the appended claims. 
     As shown in  FIGS. 1-4 , which are respectively longitudinal sectional view and lateral sectional view of a preferred embodiment of the present invention and a longitudinal sectional view and a lateral sectional view of a third transmission assembly of the preferred embodiment of the present invention, it can be clearly seen from the drawings that the present invention comprises: 
     a body  5 , wherein the body  5  comprises a substrate  2  arranged at one side thereof so that the substrate  2  and the body  5  enclose, delimit, and define a first receiving space A; 
     a cover  1 , wherein the cover  1  is arranged at one side of the body  5  in such a way that the cover  1  and the substrate  2  enclose, delimit, and define a second receiving space B; 
     an electrical machine  37 , which is mounted to a surface of the substrate  2  and is received in the second receiving space B; 
     a first transmission assembly, wherein the first transmission assembly is received in the first receiving space A and the first transmission assembly is operatively coupled to the electrical machine  37 ; 
     a second transmission assembly, wherein the second transmission assembly is received in the first receiving space A and the second transmission assembly is operatively coupled to the first transmission assembly; and 
     a third transmission assembly, wherein the third transmission assembly is received in the first receiving space A and the third transmission assembly is operatively coupled to the second transmission assembly. 
     The above-mentioned electrical machine  37  has an output spindle that comprises a toothed section mounted thereto. The substrate  2  comprises a first gear  34  mounted thereto and arranged in the first receiving space A. The toothed section and the first gear  34  mate each other and the toothed section and the first gear  34  collectively constitute the above-mentioned first transmission assembly. 
     The above-mentioned first receiving space A further receives a gear shaft  35  and a second gear  42  that is coupled to the gear shaft  35  arranged therein. The gear shaft  35  and the second gear  42  collectively constitute the above-mentioned second transmission assembly. 
     The above-mentioned third transmission assembly is made up of a central gear  26 , at least three planetary gears  6 , a planet rack  27 , a worm gear/internal gear  7 , and an output shaft  9 . The central gear  26  mates the planetary gears  6 . The planetary gears  6  mate the worm gear/internal gear  7 . The worm gear/internal gear  7  and the planet rack  27  are operable corresponding to each other. The planet rack  27  is coupled to the output shaft  9 . The central gear  26  is coaxially fixed to the second gear  42  and details will be provided hereinafter. 
     The above-described arrangement provides the primary constituent components that achieve multiple-staged transmission of the present invention. In the following, the other components that are necessary for achieving the advantages of the present invention will be described. In the linear travel structure of an electrical operating device according to the present invention, a central shaft  38  is arranged at a center of the substrate  2  and the central shaft  38  has an end coupled to the output shaft  9 . The output shaft  9  is fixed, via a coupling flange  10 , to an opening formed in a bottom of the body  5 . The planetary gears  6 , the central gear  26 , the planet rack  27 , and the worm gear/internal gear  7  collectively form a NGW mechanism. The worm gear/internal gear  7  is coupled to a manual-operation worm  28 . The manual-operation worm  28  has an end forming a projecting portion that is fixed, via a sleeve  43  and eighth bolts  44 , to one side of the body  5 , wherein the manual-operation worm  28  is coupled to the sleeve  43  in such a way as to be rotatable around a center of the sleeve  43  and the sleeve  43  is fixed to the body  5  by the eighth bolts  44 , and comprises a plurality of O rings  45  fit over an outer circumference for preventing leaking of lubricant. The manual-operation worm  28  has an opposite end that is set in clearance fit in an internal hole formed in the body  5 . The manual-operation worm  28  has a terminal portion to which a hand wheel  47  is fixed by a ninth bolt  46 . The hand wheel  47  comprises a handle mounted thereto. The output shaft  9 , the central gear  26 , the planetary gears  6 , the worm gear/internal gear  7 , and the manual-operation worm  28  collectively constitute a manual operation portion of the electrical operating device. 
     The electrical operating device is made up of the first transmission assembly, the second transmission assembly, the third transmission assembly, and the above-described manual operation portion, wherein the NWG structure of the third transmission assembly forms a core mechanism of the entire electrical operating device. 
     The body  5  has a top end to which the substrate  2  is mounted. The substrate  2  comprises electrical components and the electrical machine  37  mounted thereto. The cover  1  is mounted to the top end of the body  5 . The toothed section is formed on the output spindle of the electrical machine  37  and mates the first gear  34  for transmission of power. The first gear  34  is mounted via a flat key to the gear shaft  35 . An end of the gear shaft  35  is mounted, via a third bearing  36 , to a bearing seat  33  and an opposite end is mounted to a bearing cover  30 . The bearing seat  33  is fixed by screws to the substrate  2 . The above-mentioned toothed section of the output spindle of the electrical machine  37 , the first gear  34 , and the electrical machine  37  constitute the first transmission assembly that receives the transmission of power and the gear shaft  35  and the second gear  42  constitute the second transmission assembly. 
     The third transmission assembly is made up of the central gear  26 , the planetary gears  6 , the planet rack  27 , the worm gear/internal gear  7 , and the output shaft  9 . The central gear  26  mates the planetary gears  6 . The planetary gears  6  mate the worm gear/internal gear  7 . When the electrical machine  37  is set in operation, the manual-operation worm  28  is not allowed to rotate, whereby the worm gear/internal gear  7  is prevented from rotation by the self-locking of the manual-operation worm  28 ; the planet rack  27  is caused to rotate by the engagement between the central gear  26  and the planetary gears  6 . The planet rack  27  and the output shaft  9  are coupled to each other by first bolts  8  so that when the planet rack  27  rotates, power is transmitted through the first bolts  8  to the output shaft  9 . The output shaft  9  is coupled, at a lower end thereof, to an internal hole formed in a lower portion of the body  5  by a second bearing  25 . 
     The above-described NGW mechanism is the essential core of the entire electrical operating device. The second gear  42  is fixed by seventh bolts  41  to the central gear  26 . The central gear  26  has an end having an outer circumference in clearance fit with the first bearing  3 . The planetary gears  6  are each provided therein with a bearing collar  48 , which is mounted to the planet rack  27  through interference fitting achieved at one end of a connection shaft  49 . The planetary gear  6  and the planet rack  27  comprise a copper pad  50  arranged therebetween so that ends of the planetary gear  6  and the planet rack  27  are spaced from each other. The central gear  26  and the planetary gears  6  form external engagement, while the worm gear/internal gear  7  and the planetary gears  6  form internal engagement. Such an arrangement constitutes the NGW mechanism. 
     For manual operation, the electrical machine  37  is de-activated and does not rotate. The hand wheel  47  and the manual-operation worm  28  are coupled to each other through a flat key for driving the worm gear/internal gear  7  to rotate. Since the central gear  26  is kept fixed by the damping effect of the electrical machine  37 , the planet rack  27  is caused to rotate by the engagement between the planetary gear  6  and the worm gear/internal gear  7  thereby transmitting rotational motion to the output shaft  9 . The output shaft  9  is coupled by a spline collar  23  to a screw rod  13 , so that the power is further transmitted through the screw rod  13  to a driving nut  15 . The driving nut  15  is coupled by second bolts  19  to a nut  18 . As such, reciprocal rotation of the screw rod  13  drives the driving nut  15  to move up and down for controlling opening/closing of the valve, wherein an indication plate  16  is provided to indicate the location of the valve in order to accurately obtain the opening/closing condition of the valve. A protection hood  20  is provided in an extendible/retractable arrangement to prevent debris from entering the threaded portion of the screw rod  13  during the operation of the electrical operating device. Support posts  17  are provided for mounting the electrical operating device. 
     In the above described structure, besides the combination of the components described above, the following components are also provided for the purposes of fixing and assisting of the operation, including a first bearing  3 , a second bearing  4 , a nut  11 , a flat washer  12 , a retention lid  14 , third bolts  21 , a first bearing  22 , fourth bolts  24 , fifth bolts  29 , a bearing cover  30 , loosening prevention bolts  31 , sixth bolts  32 , a fourth bearing  39 , and a distance-setting sleeve  40 , these components being retention means necessary for achieving the structure of the present invention, but are generally irrelevant to the technical features of the present invention, so that details associated with the relationships and positions will not be provided herein. 
     The technical features that the present invention adopts to improve the known techniques are as follows: 
     The electrical operating device adopts a multiple-staged transmission arrangement to thoroughly improve severe wearing and poor transmission efficiency of the prior art and also to effectively use the entire available space in order to achieve the advantages of high transmission efficiency, high bearing capacity, high speed ratio, and small volume. 
     It will be understood that each of the elements described above, or two or more together may also find a useful application in other types of methods differing from the type described above. 
     While certain novel features of this invention have been shown and described and are pointed out in the annexed claim, it is not intended to be limited to the details above, since it will be understood that various omissions, modifications, substitutions and changes in the forms and details of the device illustrated and in its operation can be made by those skilled in the art without departing in any way from the spirit of the present invention.