Patent Publication Number: US-2004043849-A1

Title: Transmission using flat gear

Description:
TECHNICAL FIELD  
       [0001] The present invention relates to a power transmission device or transmission for transmitting power using a gear, and more particularly, to a power transmission device or transmission with a flat gear or a grooved flat gear in which grooves are formed in concentric circles on a circular plate and a circle of the grooves constitutes a single speed stage.  
       BACKGROUND ART  
       [0002] In a conventional power transmission device or transmission, a chain moves between sprockets to perform power transmission or speed change, so derailment of the chain, irregular transmission time, or contamination of a coating due to lubricant may occur during power transmission. In addition, as for a gear box type transmission made by combining spur gears, an increase in the number of gears causes the entire weight and size of the transmission to increase and complicates implementation of the transmission.  
       DISCLOSURE OF THE INVENTION  
       [0003] To solve the above-described problems, it is an object of the present invention to provide a flat gear or grooved flat gear in which grooves are formed on a circular plate, and a transmission using the gear.  
       [0004] To achieve the above object of the invention, in a first embodiment, there is provided a flat gear including a circular plate made of a predetermined material, a predetermined number of grooves formed in concentric circles on the circular plate, and a plurality of speed stages constituted by the grooves formed in the concentric circles on the circular plate.  
       [0005] In a second embodiment, there is provided a grooved flat gear including a plurality of speed stages constituted by a predetermined number of grooves formed in concentric circles on a circular plate in a rotary direction, and an open groove which is common to the plurality of speed stages.  
       [0006] In a third embodiment, there is provided a transmission including a flat gear comprising at least two speed stages constituted by a predetermined number of grooves formed in at least two concentric circles on a circular plate, as many bevel gears as the number of the speed stages of the flat gear, each bevel gear being perpendicularly coupled to the flat gear, and a spline unit coupled to the bevel gears for power transmission.  
       [0007] In a fourth embodiment, there is provided a transmission including a grooved flat gear comprising at least two speed stages and an open groove common to the speed stages in a radial direction, a bevel gear perpendicularly coupled to a groove of one of the speed stages of the grooved flat gear, and a spline unit coupled to the bevel gear for power transmission. 
     
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
     [0008] The above objects and advantages of the present invention will become more apparent by describing in detail a preferred embodiment thereof with reference to the attached drawings in which:  
     [0009]FIG. 1 is a plan view of a flat gear having three speed stages constituted by grooves which are formed in concentric circles on a circular plate according to the present invention;  
     [0010]FIG. 2 is a plan view of a grooved flat gear having a common open groove to speed stages constituted by grooves which are formed in concentric circles on a circular plate according to the present invention;  
     [0011]FIG. 3 is a diagram of a bevel gear which engages with a flat gear or a grooved flat gear according to the present invention;  
     [0012]FIG. 4 is a diagram of a spline unit which is coupled to a bevel gear to transmit the power of a flat gear or a grooved flat gear according to the present invention;  
     [0013]FIG. 5 shows a front view and a left side view of the spline unit of FIG. 4;  
     [0014]FIG. 6A is a diagram in which a flat gear is perpendicularly coupled to a power shaft by a bevel gear according to the present invention;  
     [0015]FIG. 6B is a perspective view of a fixing plate for fixing bevel gears which transmit power generated by a flat gear to a power shaft according to the present invention;  
     [0016]FIG. 6C is a sectional view in which bevel gears for transmitting power generated by a flat gear to a power shaft are coupled to a fixing plate for fixing the bevel gears according to the present invention;  
     [0017]FIG. 7 is a diagram of a transmission in which a grooved flat gear is coupled to a power shaft to change a speed according to the present invention; and  
     [0018]FIG. 8 is a perspective view of a device for transmitting power or changing a speed using a flat gear according to the present invention. 
    
    
     BEST MODE FOR CARRYING OUT THE INVENTION  
     [0019] Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the attached drawings.  
     [0020]FIG. 1 is a plan view of a flat gear having three speed stages constituted by grooves which are formed in concentric circles on a circular plate according to the present invention. A flat gear  100  has a plurality of speed stages constituted by grooves formed in concentric circles on a circular plate. In the embodiment shown in FIG. 1, there are three speed stages. The three speed stages are implemented by a low speed part  110 , a medium speed part  120 , and a high speed part  130 . A speed part for higher speed has more grooves. The grooves of the flat gear  100  all have the same size and shape and have the same shape as the tooth form of a bevel gear so that the grooves can linearly contact the bevel gear, so the grooves can transmit the same torque when the flat gear  100  perpendicularly engages the bevel gear.  
     [0021]FIG. 2 is a plan view of a grooved flat gear having three speed stages constituted by grooves which are formed in concentric circles on a circular plate and having an open groove common to grooves positioned on a line passing through the center of the circular plate in the speed stages according to the present invention. A grooved flat gear  100  includes three speed stages implemented by a low speed part  210 , a medium speed part  220 , and a high speed part  230 , and open grooves  243  and  245  common to all three speed stages.  
     [0022] The open grooves  243  and  245  are paths through which a bevel gear perpendicularly coupled to the grooves of the grooved flat gear  200  to transmit the torque of the grooved flat gear  200  slides from one speed stage to another speed stage. For example, when a bevel gear coupled to the grooves of the low speed part  210  is shifted to a high or medium speed, the bevel gear slides along the open grove  243  or  245  to accomplish the shift.  
     [0023]FIG. 3 is a diagram of a bevel gear which engages with a flat gear or a grooved flat gear according to the present invention. The bevel gear has the same module as each groove of a flat gear or a grooved flat gear shown in FIGS.  1  or  2 . A tooth form  310  of the bevel gear is coupled to a groove of a flat gear or a grooved flat gear, thereby transmitting torque. A spline protrusion  320  has a function of spline coupling the bevel gear to a power shaft transmitting the power of a gear.  
     [0024]FIG. 4 is a diagram of a spline unit  400  which couples to a bevel gear to transmit the power of a flat gear or a grooved flat gear according to the present invention. The spline unit  400  includes a long spline groove  410  and a short spline groove  420 .  
     [0025] The spline unit  400  is coupled to a flat gear  100  such that the long spline protrusion  410  is coupled to a power shaft and the short spline protrusion  420  is coupled to one of as many bevel gears as the number of speed stages the flat gear  100  has. When the spline unit  400  moves in the radial direction of the flat gear  100 , the short spline protrusion  420  is coupled to a bevel gear coupled to one speed stage of the flat gear  100 , thereby performing transmission of torque.  
     [0026]FIG. 5 shows a front view and a left side view of the spline unit  400  of FIG. 4. When the flat gear  100  is used for power transmission, the long spline protrusion  410  is coupled to a power shaft and the short spline protrusion  420  is coupled to a bevel gear. When the grooved flat gear  200  is used for power transmission, the long spline protrusion  410  is coupled to a bevel gear and the short spline protrusion  420  is coupled to a power shaft.  
     [0027]FIG. 6A is a diagram in which a flat gear is perpendicularly coupled to a power shaft by a bevel gear according to the present invention. A flat gear  600  has three speed stages constituted by grooves formed in concentric circles on a circular plate. The speed stages are implemented by a low speed part  610 , a medium speed part  620 , and a high speed part  630 .  
     [0028] Once the flat gear  600  is rotated by a driving shaft  640 , bevel gears  663 ,  665 , and  667  perpendicularly coupled to grooves of the flat gear  600  rotate, and one of the bevel gears  663 ,  665 , and  667  is coupled to a short spline protrusion  653  of a spline unit  650 , thereby transmitting torque to a power shaft  670 . The power shaft  670  is coupled to the spline unit  650  through the long spline protrusion  655 . In an example of power transmission, when low speed torque is transmitted to the power shaft  670  in a state in which the low speed bevel gear  663  is coupled to the low speed part  610  of the flat gear  600 , the spline unit  650  is moved so that the high speed bevel gear  667  can be coupled to the short spline protrusion  653  in order to changing a speed. As a result, high speed torque can be transmitted to the power shaft  670 . Here, when one bevel gear is coupled to the short spline protrusion  653 , the remaining two bevel gears rotate without transmitting torque. A method of fixing the three bevel gears  663 ,  665 , and  667  will be described with reference to FIGS. 6B and 6C.  
     [0029]FIG. 6B is a perspective view of a fixing plate for fixing bevel gears which transmit power generated by a flat gear to a power shaft according to the present invention. FIG. 6C is a sectional view in which bevel gears for transmitting power generated by a grooved flat gear to a power shaft are coupled to a fixing plate for fixing the bevel gears according to the present invention.  
     [0030] In a method of fixing the two bevel gears  663  and  665 , a fixing plate  680  is inserted between the two bevel gears  663  and  665 , and the bevel gears  663  and  665  have ball keeping grooves  681  and  683 . A ball is pressed and inserted between the ball keeping grooves  681  and  683  and fixed by the fixing plate  680  so that the bevel gears  663  and  665  can rotate independently. Spline grooves  691  and  693  are used for fixing the bevel gears  663  and  665  to a spline unit. If three speed stages are set, three bevel gears are fixed as described above so that torque can be transmitted to a power shaft.  
     [0031]FIG. 7 is a diagram of a transmission in which a grooved flat gear is coupled to a power shaft to change a speed according to the present invention. The grooved flat gear has three speed stages and an open groove common to the three speed stages so that a bevel gear can move to change a speed.  
     [0032] A grooved flat gear  700  includes speed stages implemented by a low speed part  710 , a medium speed part  720 , and a high speed part  730 , and open grooves  753  and  755  common to the three speed stages. The grooved flat gear  700  is perpendicularly coupled to a bevel gear  770 , and the bevel gear  770  is coupled to a spline unit  760  through a spline protrusion  763 , so the torque of the grooved flat gear  700  is transmitted.  
     [0033] For the transmission of torque, a driving shaft  740  generates torque to thus rotate the grooved flat gear  700 . As a result, the bevel gear  770  coupled to one of the low speed part  710 , the medium speed part  720 , and the high speed part  730  of the grooved flat gear  700  rotates. When changing a speed, the bevel gear  770  slides along one of the open groves  753  and  755  to one of the speed stages, i.e., the low speed part  710 , the medium speed part  720 , and the high speed part  730 , when the bevel gear  770  engages one of the open grooves  753  and  755 .  
     [0034]FIG. 8 is a perspective view of a device for transmitting power or changing a speed using a flat gear according to the present invention. Two flat gears are coupled to a power shaft for transmission of torque.  
     [0035] A driving flat gear  810  and a driven flat gear  860  are connected by a power shaft  830 . The power shaft  830  is fixed to a frame by a power shaft support  840 . Three bevel gears  821 ,  823 , and  825  are spline coupled to the driving side of the power shaft  830 , and three bevel gears  851 ,  853 , and  855  are spline coupled to the driven side of the power shaft  830 .  
     [0036] Once torque is generated by a driving shaft  817 , the driving flat gear  810  rotates, and the torque of the driving flat gear  810  is transmitted to the driven side through the power shaft  830  which is spline coupled to the low speed bevel gear  821 , the medium speed bevel gear  823 , or the high speed bevel gear  825  coupled to a low speed part  811 , a medium speed part  813 , or a high speed part  815  to transmit the torque.  
     [0037] The driven side receives the torque from the low speed bevel gear  851 , the medium speed bevel gear  853 , or the high speed bevel gear  855  which is perpendicularly coupled to a low speed part  861 , a medium speed part  863 , or a high speed part  865  of the driven flat gear  860  according to a rotary speed. As a result, the driving flat gear  860  rotates, and the torque is transmitted through a driven shaft  867 .  
     [0038] According to the present invention, a flat gear, a grooved flat gear, or a bevel gear is made of high strength plastic, which decreases the entire weight of a transmission, thereby increasing the efficiency of power transmission.  
     [0039] Industrial Applicability  
     [0040] As described above, according to the present invention, a single flat gear or grooved flat gear is perpendicularly coupled to at least one bevel gear disposed at a power shaft for power transmission and speed change, thereby solving the problems of contamination of a coating due to lubricant, derailment of a chain, or irregular transmission time occurring in a conventional chain type transmission. In addition, as compared to a gear box type transmission using spur gears, the present invention decreases the weight and size of a transmission and increases the efficiency of power transmission, thereby simplifying the structure of the transmission and reducing the manufacturing cost and malfunction rate.