Abstract:
An adjustable crank for adjusting the swinging-angle of a fan comprises a first and a second eccentric disks, the first disk is rotatablely inserted in the second disk, a ring-shape spring is disposed between the engaging surfaces of them to couple them with predetermined torque. A crank pin is eccentrically and integrally formed on the first disk. The second disk is provided with a rotation means for the second disk being turned to rotate about a center axis, which is eccentric with respect to the engaging surfaces. A rotary knob is fixedly mounted on the end of the crankpin for manually turning the first disk to rotate relative to the second disk. Thereby the crank length can be continuously adjusted and self-fixed after being adjusted. Apparently, it is unusually simple in structure, very easy to adjust, especially convenient and cheap in manufacture, and reliable in running.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates generally to a crank, and more particularly to an adjustable crank of swinging mechanism, which is particularly adapted for swinging mechanism such as employed in oscillating electric fans or heaters. 
     2. Description of the Prior Art 
     Conventional oscillating electric fans available in the market are commonly controlled by an unadjustable swinging mechanism that makes the fan swing at an unadjustable angle range. A user can only choose between a fixed mode (no swing) and a swinging mode with a predefined swinging-angle. Such functions are hard to suit the current environment and meet a user&#39;s requirements. U.S. Pat. No. 5,639,213 is an example of such designs, which employs a commonly used crank and rocker mechanism in such an oscillating fan. U.S. Pat. No. 5,720,594 is another example that discloses a crank and slotopening mechanism for a fan oscillating in two axes. 
     In order to overcome such weakness, many improved schemes have been developed. Among them, some use a crank with changeable length, which leads the swinging-angle adjustable. U.S. Pat. Nos. 3,977,260, 5,217,417 and 5,931,056 are examples of prior patents that disclose such types of fans and also various crank arrangements used for swinging such fans. Unfortunately, the structures of these schemes are so complex that they are hardly adopted and applied widely. As disclosed in China Pat. No. 95240392, a crankpin of the crank can be moved in a slot resulting in corresponding change of the crank length. But such a crank based on above scheme is not convenient for performing swingiong-angle adjusting, and its structure is not simple. Furthermore, even more complex structures may be seen in some other schemes. 
     SUMMARY OF THE INVENTION 
     According to the present invention, a novel adjustable crank is provided to solve the problemes mentioned above. Wherein a simple eccentric mechanism is used to change the crank length, an ingenious coupling means is used to self-fix the crank length, an adjusting means is used to conveniently adjust the crank length, furthermore, several additional means are used for making adjustment to the crank length more conveniently. 
     The adjustable crank according to the present invention comprises a first eccentric disk, a second eccentric disk, a coupling means and an adjusting means. The first disk is provided with a recess having an inner cylindrical surface and an integrally formed crankpin, which is eccentric with respect to the inner cylindrical surface. The second disk is provided with an outer cylindrical surface and a rotation means for the second disk be turned to rotate about a center axis, which is eccentric with respect to the outer cylindrical surface. The second disk is rotatablely inserted in the first disk, and so the inner cylindrical surface and the outer cylindrical surface are engaged each other. The coupling means is disposed between the first and second disks for coupling both of them with predetermined coupling torque. The predetermined coupling torque is large enough to ensure that the relative positions of the first and second disks can be maintained during operation so that power actuating the fan head to swing can be transmitted through the crank. The adjusting means is positioned on the end of the crankpin for manually turning the first disk to rotate relative to the second disk with adjusting torque, which is greater than the coupling torque. Thereby the crank length is adjustable and can be self-fixed after being adjusted. The crank length can be adjusted continuously from zero to the maximum value; correspondingly the swinging-angle of a fan can be adjusted from 0 to a maximum of 120 degrees. 
     The second disk might provided with a axial mounting hole or with a spindle and a gear, the mounting hole or the spindle and the gear are coaxially disposed with the center axis. Similar to conventional unadjustable cranks the mounting hole is fixedly mounted on an output shaft of an actuating device and actuated to rotate by the output shaft, or the spindle is rotatablely inserted in a locating hole and the gear is actuated to rotate by a pinion of the actuating device. The crankpin is articulated with one end of a connecting rod of a crank and rocker mechanism or slidablely inserted in a slotopening of a crank and slotopening mechanism. 
     One type of the coupling means is configured such that a pair of annular engaging zones respectively positioned on the first and second disks are forced into coupling together by predetermined elastic force resulted from elastic distortion of at least one of said disks. But then said disks can be forced to rotate relatively by said adjusting means. Said annular engaging zones may be inner cylindrical surface with outer cylindrical surface or annular groove with annular bulge. 
     Another type of the coupling means comprises a plurality of concaves and at least one convex meshing with the concaves. The concaves and convex are respectively formed on the engaging surfaces of the first disk and second disks. The concaves and the convex can be forced to slip across each other due to elastic deforming of at least one of said disks by said adjusting means, and sound signals and touch signals will be generated at the same time. 
     Another type of the coupling means comprises a spring means positioned in an annular chamber formed on the engaging surfaces. The spring means can be turned to rotate relative to at least one of said disks and exerts predetermined pressure force on the same disk to couple it with frictional force. Said spring means is selected from the group consisting of metallic round split ring, metallic polygon split ring, elastomeric O-ring, and elastomeric strip, etc. Said annular chamber may be a combination of two annular grooves, one is formed on the first disk and the other on the second disk. Said spring means is partially positioned in one of said grooves and partially positioned in other one so that the axial relative movement of the first and second disks is further limited. 
     Another type of the coupling means comprises a spring means and at least one steel ball located in a radial hole formed on the second disk, the steel ball is biased to abut against the first disk by predetermined force actuated by the spring means. Furthermore, the first disk can be shaped to include a plurality of concaves or axial grooves formed on the inner cylindrical surface, the steel ball is biased to abut against the concaves or axial grooves. While adjusting crank length, the concaves or axial grooves can be forced to slip across the steel ball, and sound signals and touch signals will be generated at the same time, hereby such coupling means is accompanied by signaling function. 
     The adjusting means comprises a rotary knob, one end of the rotary knob has an axial hole securely connected with the end of the crankpin; the other end has a handwheel extended out of the through hole formed on the rear housing of the fan motor, so that adjusting torque is directly applied to the handwheel with hand. The handwheel may be concentrical with the crankpin, but preferably is concentrical with the inner cylindrical surface of the first disk. 
     Alternatively, the adjusting means is configured such that the end of the crankpin being shaped like a screw head, such as slotted head, cross recess head, hex head or square head. Thus, the adjusting torque can be manually applied to the crankpin via a universal screwdriver or other tools. 
     According to the present invention a signaling means is further comprised for generating sound signal and touch signal during the crank length adjusting process. One type of the signaling means comprises a plurality of axial grooves and at least one axial ridge meshing with said grooves. The grooves and the ridge are respectively formed on the engaging surfaces of the disks. While adjusting cxrank length, said grooves and ridge can be forced to slip across each other due to elastic distortion of at least one of the disks, sound signal and touch signal will be generated at the same time. 
     According to the present invention a circumferential limiting measns is further comprised, by which the relative rotation of the first and second disks is delimited at two ultimate positions. One of the ultimate positions corresponds to the maximum crank length, and the other one corresponds to the minimum crank length. So the first and second disks can only be to-and-fro turned relatively between these two ultimate positions, one turning direction corresponds to increasing the crank length and the other turning direction corresponds to decreasing the crank length. 
     One type of the circumferential limiting means includes two axial projecting elements, which are respectively formed on the first and second disks and blocked each other at two ultimate positions. Another type of the circumferential limiting means includes an arc shape groove and an axial projecting element extending into the arc groove, the arc groove and the projecting element are respectively formed on the first and second disks and blocked each other at two ultimate positions. 
     According to the present invention an axial limiting means is further comprised to limit axial relative movement of the disks. Said limiting means includes a pair of annular shoulders adjacent each other formed respectively on said engaging surfaces. In an alternative way, said limiting means includes an annular bulge and an annular groove formed respectively on said engaging surfaces and meshed each other. 
     The first disk, second disk and rotary knob as described above can be made of metal or plastic material, but preferably are molded from plastic. 
     When adjusting crank length, user only need to turn the rotary knob to change the crank length and then the crank length is self-fixed at the desired value by the coupling means. All appearance, the adjustable crank according to the present invention therefore has the advantages of being especially simple in structure, being significantly convenient and cost effective in manufacture, being very easy to adjust during operation and being reliable in running. 
     Accordingly, it is a principal object of the present invention to provide an adjustable crank, which is especially simple in structure and easy to adjust the crank length. 
     It is a further object of the present invention to provide a coupling means, which can be used to fix the crank length automatically after the crank length being adjusted. 
     It is a further object of the present invention to provide an adjusting means, which can be used to adjust the crank length conveniently. 
     It is an additional object of the present invention to provide a signaling means, which can be used to adjust the crank length efficiently. 
     It is an additional object of the present invention to provide a circumferential limiting means, which can be used much more conveniently to adjust the crank length. 
     Further object and advantage is to provide an adjustable crank, which can be simply used to replacing the constant length crank of the existing oscillating fans. 
     Other objects and advantages will become apparent from a consideration of the ensuing drawings and description. 
    
    
     BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING 
     FIG. 1 is a front elevation view of an oscillating fan embodying an adjustable crank according to the present invention. 
     FIG. 2 is a sectional view of an essential embodiment of an adjustable crank according to the present invention. 
     FIG. 3 is a sectional view similar to FIG. 2, wherein a circumferential limiting means and an axial limiting device are further comprised and the adjusting means comprises a rotary knob. 
     FIG. 4 is a cross sectional view taken along line  1 — 1  in FIG.  3 . 
     FIG. 5 is a sectional view similar to FIG. 3 showing the alternative circumferential limiting means, axial limiting means and a modified rotary knob. 
     FIG. 6 is a cross sectional view taken along line  2 — 2  in FIG.  5 . 
     FIG. 7 is a sectional view similar to FIG. 5 showing the alternative coupling means according to the present invention. 
     FIG. 8 is a cross sectional view taken along line  3 — 3  in FIG.  7 . 
     FIG. 9 is a sectional view of a further embodiment of an adjustable crank according to the present invention wherein the coupling means comprises an elastomeric ring. 
     FIG. 10 is a cross sectional view taken along line  4 — 4  in FIG.  9 . 
     FIG. 11 is a sectional view similar to FIG. 9 showing the alternative spring means, which is a metallic polygon split ring. 
     FIG. 12 is a cross sectional view taken along line  5 — 5  in FIG.  11 . 
     FIG. 13 is a sectional view similar to FIG. 9 showing the alternative spring means, which is a metallic round split ring. 
     FIG. 14 is a cross sectional view taken along line  6 — 6  in FIG.  13 . 
     FIG. 15 is a cross sectional view taken along line  7 — 7  in FIGS. 9,  11 ,  13 . 
     FIG. 16 is a sectional view of a further embodiment, in which the coupling means comprises two steel balls and a compression spring. 
     FIG. 17 is a cross sectional view taken along line  8 — 8  in FIG.  16 . 
     FIG. 18 is a sectional view of a further embodiment, in which a gear and a spindle are integrally formed with the second disk. 
     FIG. 19 is a sectional view similar to FIG. 18 showing the alternative coupling means, which comprises a spring means. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     FIG. 1 is a front elevation view of a novel fan  20 . Visible in this view are a base or pedestal  22  for supporting said fan on an environmental surface, a fan motor and fan blade assembly  24  for propelling air, a connecting device  26  for connecting said fan motor and fan blade assembly  24  pivotally on said base  22 , and a swinging mechanism  28  containing an adjustable crank  30  which provides the principal novel features of the present invention. 
     As shown in FIG. 2, the essential embodiment of the adjustable crank according to the present invention comprises a first eccentric disk  32 , a second eccentric disk  34 , a coupling means and an adjusting means. Disk  32  is shaped to include an inner cylindrical surface  36  and an integrally formed crankpin  38 . Crankpin  38  is eccentric with respect to inner cylindrical surface  36 . Disk  34  is shaped to include an outer cylindrical surface  36 ′ and an axial mounting hole  40 . Outer cylindrical surface  36 ′ is eccentric with respect to mounting hole  40 . Disk  34  is rotatablely inserted in disk  32  to form an eccentric mechanism. Inner cylindrical surface  36  is engaged with outer cylindrical surface  36 ′. Used as a coupling means, the engaging surfaces are forced into coupling together by predetermined elastic force of disk  32  itself. The adjusting means is simply a slot  42  formed on the end of crankpin  38 , it is used for manually turning disk  32  with screwdriver. Therefore disk  32  and disk  34  are coupled together by the predetermined coupling torque. The coupling torque is kept constant on said engaging surfaces, but then disk  32  can be manually forced to rotate relative to disk  34  by said adjusting means. 
     An alternative adjusting means, which comprises a rotary knob  44 , can be seen in FIGS. 3 and 5. One end of rotary knob  44  has a hole fixedly mounted on the end of crankpin  38 , and the other end has a handwheel  46  extended out of the through hole of the protective cover of the fan motor (not shown). The axis of handwheel  46  may be concentric with the axis of crankpin  38  as shown in FIG. 3 or concentric with the axis of inner cylindrical surface  36  as shown in FIG.  5 . One may directly turn rotary knob  44  to adjust the crank length. 
     An additional axial limiting device may be further included to limit axial relative movement of disk  32  and disk  34 . One type of the limiting device is a pair annular steps or shoulders  66  and  66 ′ adjacent each other, which are respectively formed on inner cylindrical surface  36  and outer cylindrical surface  36 ′ as shown in FIG.  3 . Another type of the axial limiting device is an annular groove  68  and a annular bulge  68 ′, which are respectively formed on inner cylindrical surface  36  and outer cylindrical surface  36 ′ as shown in FIG.  5 . 
     As shown in FIGS. 7 and 8, used as an alternative coupling means, a plurality of concaves  70 ′ are formed on outer cylindrical surface  36 ′ of disk  34 . Two convexes  70  meshed with concave  70 ′ are formed on inner cylindrical surface  36  of disk  32 . Therefore disk  32  and disk  34  are coupled together by predetermined meshinmg force. But then convexes  70  can be forced to slip across concaves  70 ′ due to elastic deforming of disk  32 , and sound signals and touch signals can be sent out at the same time. Said sound and touch signals are helpful to feel the magnitude of crank length changing. 
     As shown in FIGS. 9 to  15 , another alternative coupling means further comprises a spring means  72 , which is arranged in an annular chamber  74  formed on the engaging surfaces of disks  32  and  34 . Spring means  72  may be an O-ring molded from elastic rubber or plastic as shown in FIGS. 9 and 10. It exerts pressure force on both disks  32  and  34  and can be forced to rotate relative to both disks  32  and  34  by adjusting means. As shown in FIGS. 11 and 12, wherein alternative spring means  72  is a steel polygon split ring. It exerts pressure force on both disks  32  and  34  and can be forced to rotate relative to both disks  32  and  34  by adjusting means too. As shown in FIGS. 13 and 14, wherein alternative spring means  72  is a steel round split ring. It exerts pressure force on disk  32  only. It can be forced to rotate relative to disk  32  by adjusting means, but is prevented from rotating relative to disk  34  by a stopper  76 . Therefore disk  32 , spring means  72  and disk  34  are coupled together. The predetermined coupling torque (friction torque) is large enough to ensure that the relative position of them can be maintained during operation, and disk  32  can be manually forced to turn relative to disk  34  by said adjusting means to changing the crank length. 
     In order to further limit axial relative movement of disk  32  and disk  34 , as shown in FIGS. 9,  11 , and  13 , an annular groove  78  is formed on inner cylindrical surface  36  of disk  32 , spring means  72  is partially positioned into and abut against annular groove  78 . 
     As shown in FIGS. 9,  11 ,  13 , and  15 , used as an additional signaling means a plurality of axial grooves  80  and two axial ridges  80 ′ meshed with grooves  80  are respectively formed on said engaging surfaces. While adjusting the crank length, grooves  80  can be forced to slip across ridges  80 ′ due to elastic deforming of disk  32  and sound signals and touch signals can be sent out at the same time. 
     As shown in FIGS. 16 and 17, used as an alternative coupling means, one compression spring  82  and two steel balls  84  are located in a radial hole  86  formed on disk  34 , and disk  32  is shaped to include a plurality of concaves  88 . Steel balls  84  apply predetermined pressure force actuated by spring  82  on concaves  88 , but then concaves  88  can be forced to slip across steel balls  84  and sound signals and touch signals can be sent out at the same time. 
     As shown in FIGS. 3 to  6 , an additional circumferential limiting means may be further comprised. Herein an arc shape groove  60 ′ and an axial projecting element  60  extending into arc groove  60 ′ are formed respectively on disks  34  and  32  as shown in FIGS. 3 and 4. Arc shape groove  60  and axial projecting element  60 ′ are blocked each other at two ultimate positions of relative rotation between disks  32  and  34 . One is the maximum crank length position, and the other is the minimum crank length position. Therefore disk  32  can only be to-and-fro turned relative to disk  34  such that one turning direction increases the crank length and the other decreases the crank length. Alternatively used as a limiting means two axial projecting elements  62  and a  62 ′ are formed respectively on disks  32  and  34  as shown in FIGS. 5 and 6. 
     As shown in FIGS. 1,  2  and  5 , mounting hole  40  is securely connected with an output shaft  48  of an actuating device  50  by screw  52  or  52 ′. There is an opening  54  or  54 ′ on the disk  32  for assembling or disassembling adjusable crank. Crankpin  38  is articulated with one end of a connecting bar  56  of a crank and rocker mechanism  58  as shown in FIG. 1 or inserted into a slotopening of a crank and slotopening mechanism (not shown). The adjustable crank is actuated to rotate by output shaft  48 . Power is transmitted from the actuating device  50  to connecting bar  56  through output shaft  48 , disk  34 , coupling means and disk  32 . Said predetermined coupling torque is large enough to withstand the reaction torque caused by connecting bar  56  or the slotopening during operation and therefore to ensure that the crank length can be kept. While adjusting crank length, you may directly turn rotary knob  44  or use a screwdriver to force slot  42  to turn. Thereby disk  32  will be rotated relative to disk  34 , and the crank length will be changed to a suitable value. Then the crank length will be self-fixed by the coupling means. And the fan will swing with a new swinging-angle, which is determined by the changed crank length. 
     FIG. 18 shows another embodiment of the adjustable crank according to the present invention. Which comprises a first disk  132 , a second disk  134 , a coupling means and an adjusting means. Disk  132  is shaped to include an inner cylindrical surface  136 , an integrally formed crankpin  138  eccentric with respect to inner cylindrical surface  136 , and an annular groove  194  coaxially formed on inner cylindrical surface  136 . Disk  134  is shaped to include an outer cylindrical surface  136 ′, a spindle  148 , a gear  190 , and an annular bulge  194 ′ coaxially formed on outer cylindrical surface  136 ′. Spindle  148  and gear  190  are eoncentric with respect to outer cylindrical surface  136 ′. Disk  134  is rotatablely inserted into disk  132 . Groove  194  and bulge  194 ′ are forced into engaging each other by elastic force of disks  132  and  134 , so that disks  132  and  134  are coupled together. Used as a limiting means two axial projecting elements  162  and  162 ′ are respectively formed on disks  132  and  134 . 
     As shown in FIG. 19, an alterlative coupling means comprises a metallic round split ring  172  positioned in an annular chamber disposed between disks  132  and  134 . Split ring  172  is rotatable relative to disk  132  and exerts predetermined pressure force on disk  132 , but is prevented from turning relative to disk  134  by a stopper. Used as a signaling means a plurality of concaves  180  and two convexes  180 ′ meshing with concaves  180  are respectively formed on engaging surfaces  136  and  136 ′. 
     Similar to a conventional unadjustable crank, the spindle  148  is rotatablely mounted in a hole under an actuating device, and gear  190  is meshed with a pinion of the actuating device (not shown). The disk  134  is actuated to rotate about the axis of spindle  148  by the pinion. The structures of the other part are the same as that described above and therefore the description is omitted here. 
     The embodimentes of the present invention are intended to be merely exemplary and those skilled in the art shall be able to make numerous variations and modifications to it without departing from the spirit of the present invention. All such variations and modifications are intended to be within the scope of the present invention as defined in the appended claims.