Patent Abstract:
A remote control toy car control system is constructed to include a dual-gearshift transmission mechanism coupled to the engine of the remote control toy car for transmission output power of the engine between a high torque position and a low torque position, a forward backward transmission control mechanism coupled to the output end of the dual-gearshift transmission mechanism for controlling forward/backward movement of the toy car, and a differential assembly coupled to the forward backward transmission control mechanism for enabling the rear wheels of the toy car to turn at different speeds when going round corners.

Full Description:
BACKGROUND OF THE INVENTION 
     The present invention relates to a remote control toy car and, more particularly, to a remote control toy car control system, which has a dual-gearshift position transmission mechanism, a forward backward transmission control mechanism, and a differential assembly arranged into a system. 
     Regular gasoline engine remote control toy cars commonly use a transmission mechanism to increase the torque. However, because the transmission mechanism of a conventional gasoline engine remote control toy car provides only one transmission mode, it is less efficient to accelerate the speed, and the torsion cannot be increased during low speed. In order to eliminate these problems, dual-gearshift position transmission mechanisms are developed. However, prior art dual-gearshift position transmission mechanisms are commonly heavy, complicated, and expensive. Furthermore, the parts of the prior art high-precision dual-gearshift position transmission mechanisms wear quickly with use. 
     Further, regular gasoline engine remote control toy cars can be controlled to move forwards as well as backwards. However, the forward transmission and the backward transmission are controlled by two separated systems, i.e., when moving the toy car forwards, the user must start the forward transmission system to drive the toy car forwards; when moving the toy car backwards, the user must stop the forward transmission system and then start the backward transmission system. This forward backward transmission design is complicated, consumes much gasoline, and requires much installation space. 
     Like real cars, the wheels at the inner side and the wheels at the outer side have different speed of revolution when going round corners. In order to balance the speed between the wheels at the inner side and the wheels at the outer side when going round corners, a speed differential assembly shall be installed. However, because the forward transmission mechanism, the backward transmission mechanism, and the differential assembly are separated mechanisms, they cannot be installed in a common housing. Therefore, prior art gasoline remote control toy cars are commonly heavy and expensive. 
     SUMMARY OF THE INVENTION 
     The present invention has been accomplished to provide a remote control toy car control system, which eliminates the aforesaid drawbacks. It is one object of the present invention to provide a remote control toy car control system, which has a dual-gearshift position transmission mechanism, a forward backward transmission control mechanism, and a differential assembly arranged into a system. It is another object of the present invention to provide a remote control toy car control system, which achieves the advantages of high/low dual-gearshift position automatic shifting control, easy forward/backward steering control, impact structure, high economic effect, high performance, and stable functioning. To achieve these and other objects of the present invention, the remote control toy car control system comprises a dual-gearshift position transmission mechanism, a forward backward transmission control mechanism, and a differential assembly. The dual-gearshift position transmission mechanism comprises a first drive gear and a second drive gear fixedly mounted on the output shaft of the engine of the remote control toy car; a first driven gear meshed with the first drive gear; a second driven gear meshed with the second drive gear, the gear ratio between the first second drive gear and the second driven gear being smaller than the gear ratio between the first drive gear and the first driven gear; a transmission tube connected in series to the first driven gear and the second driven gear; a one-way axle bearing mounted between the transmission tube and the first driven gear; and a clutch fixedly mounted on the transmission tube and coupled to the second driven gear. The forward backward transmission control mechanism comprises a first gear fixedly mounted on the transmission tube of the dual-gearshift position transmission mechanism, the first gear comprising external teeth arranged around the outer diameter thereof and internal teeth arranged around the inner diameter thereof; a second gear, the second gear comprising internal teeth arranged around the inner diameter thereof and external teeth arranged around the outer diameter thereof; a movable gear adapted to be moved between a first position where the movable gear is meshed with the internal teeth of the first gear, and a second position where the movable gear is meshed with the internal teeth of the second gear; a first idle gear wheel meshed with the external teeth of the first gear; and a second idle gear wheel meshed with the first idle gear wheel and the external teeth of the second gear. The differential assembly comprises a shell; a hollow polygonal shaft mounted in the shell and inserted through the movable gear of the forward backward transmission control mechanism for enabling the movable gear to be moved axially along the polygonal shaft; a first center axle axially inserted through the hollow polygonal shaft and the transmission tube for free rotation relative to the hollow polygonal shaft and the transmission tube; a first center axle gear fixedly mounted on the first center axle; a second center axle axially coupled to the first center axle for enabling the second center axle and the first center axle to be separately rotated; a second center axle gear fixedly mounted on the second center axle; a plurality of first planet gears mounted in the shell and respectively meshed with the second center axle gear; and a plurality of second planet gears mounted in the shell and respectively meshed with the first center axle gear. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is an exploded, sectional plain view of a remote control toy car control system according to the present invention. 
     FIG. 2 is a sectional assembly view of the remote control toy car control system according to the present invention. 
     FIG. 3 is similar to FIG. 2 but showing the movable gear moved into engagement with the first gear of the forward backward transmission control mechanism according to the present invention. 
     FIG. 4 is another exploded, sectional plain view of the remote control toy car control system according to the present invention. 
     FIG. 5 is front and side sectional views of the first gear of the forward backward transmission control mechanism according to the present invention. 
     FIG. 6 is front and side sectional views of the second gear of the forward backward transmission control mechanism according to the present invention. 
     FIG. 7 is front and side sectional views of the movable gear of the forward backward transmission control mechanism according to the present invention. 
     FIG. 8 is a sectional plain view of the differential assembly of the present invention, showing the relationship between the second center axle gear and the first and second planet gears. 
     FIG. 9 is a sectional plain view of the present invention showing the connection between the dual-gearshift position transmission mechanism and the differential assembly. 
     FIG. 10 is a schematic drawing showing the remote control toy car control system of the present invention installed in the remote control toy car. 
     FIG. 11 is a sectional plain view of an alternate form of the dual-gearshift position transmission mechanism according to the present invention. 
     FIG. 12 is an exploded, sectional plain view of an alternate form of the remote control toy car control system according to the present invention. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Referring to FIGS. 1,  2 , and  10 , a remote control toy car control system in accordance with the present invention is generally comprised of a dual-gearshift position transmission mechanism  1 , a forward backward transmission control mechanism  2 , and a differential assembly  3 . The dual-gearshift position transmission mechanism  1 , the forward backward control mechanism  2 , and the differential assembly  3  are arranged together and mounted on holders  5  (see FIG.  2 ). The positioning of the control system in the frame structure of the toy car is as shown in FIG.  10 . 
     Referring to FIGS. 1 and 2 again, the dual-gearshift position transmission mechanism  1  comprises a first drive gear  101  and a second drive gear  102  connected to the engine  10 , a first driven gear  11 , a second driven gear  12 , a clutch  13 , a sleeve  14 , and a one-way axle bearing  15 . The first drive gear  101  and the second drive gear  102  are fixedly mounted on the output shaft of the engine  10 . The first drive gear  101  has a diameter smaller than the second drive gear  102 . The one-way axle bearing  15  is mounted in the center hole of the first driven gear  11 . The sleeve  14  is mounted in the center hole of the second driven gear  12 . The first driven gear  11  and the second driven gear  12  are arranged in parallel between two holders  5  and respectively meshed with the first drive gear  101  and the second drive gear  102 . The gear ratio between the first driven gear  11  and the first drive gear  101  is 5:1. The gear ratio between the second driven gear  12  and the second drive gear  102  is 3:1. The two holders  5  have the respective center hole mounted with a respective two-way axle bearing  16 . Further, a transmission tube  26  is inserted through the two-way axle bearings  16  in the two holders  5 , the clutch  13  and the one-way axle bearing  15 , and fixedly secured thereto. The transmission tube  26  has an inner thread  261  at one end. 
     When starting the engine  10 , the first drive gear  101  and the second drive gear  102  are synchronously rotated with the output shaft of the engine  10 , and drive the first driven gear  11  and the second driven gear  12  to rotate synchronously. Because the gear ratio between the first drive gear  101  and the first driven gear  11  is greater than the gear ratio between the second drive gear  102  and the second driven gear  12  and because the clutch  13  is disengaged from the sleeve  14  at the initial stage after started the engine  10 , the second driven gear  12  is rotated at a relatively higher speed than the first driven gear  11 . However, because the sleeve  14  is disengaged from the clutch  13 , it runs idle. Therefore, at the initial stage after started the engine  10 , the first drive gear  101  drives the first driven gear  11  to rotate at a low speed, and the first driven gear  11  drives the one-way axle bearing  15  to rotate the transmission tube  26  at a low speed. When rotating the transmission tube  26 , the clutch  13  is rotated with the transmission tube  26 . When accelerating the engine  10 , the revolving speed of the transmission tube  26  is increased. When the revolving speed of the transmission tube  26  reached the set value, the internal stop member (not shown) of the clutch  13  is forced outwards by the centrifugal force into engagement with the coupling element (not shown) of the sleeve  14 , thereby causing the second drive gear  102  to rotate the second driven gear  12  at a high speed, and therefore the transmission tube  26  is rotated at a high speed. Further, when the speed of the engine  10  dropped below the set value, the internal stop member of the clutch  13  is disengaged from the sleeve  14 , and the output power of the engine  10  is transmitted through the first drive gear  101 , the first driven gear  1  and the one-way axle bearing  15  to the transmission tube  26  to reduce the revolving speed of the transmission tube  26 , enabling the transmission tube  26  to provide a relatively higher torsional force. Thus, the dual-gearshift position transmission mechanism achieves dual-gearshift position switching automatically. 
     Referring to FIG. 4, the forward backward transmission control mechanism is comprised of a case formed of a first shell  20  and a second shell  20 A, a first gear  21 , a second gear  22 , a movable gear  23 , a first idle gear wheel  24 , and a second idle gear wheel  25 . The first gear  21 , the second gear  22 , the movable gear  23 , the first idle gear wheel  24 , and the second idle gear wheel  25  are mounted inside the case of the first shell  20  and the second shell  20 A. 
     As shown in FIG. 5, the first gear  21  has a threaded gear shaft  213  threaded into the inner thread  261  of the transmission sleeve  26 , external teeth  211  arranged around the outer diameter, and internal teeth  212  arranged around the inner diameter. 
     As shown in FIG. 6, the second gear  22  has external teeth  221  arranged around the outer diameter, and internal teeth  222  arranged around the inner diameter. 
     As shown in FIG. 7, the movable gear  23  has an annular groove  232  around the periphery, a lever  28  fastened to the annular groove  232 , and external teeth  231  around the periphery. The movable gear  23  further has a polygonal center through hole coupled to the polygonal shaft  31  of the differential assembly  3  such that the movable gear  23  can be moved axially along the polygonal shaft  31  of the differential assembly  3  but is prohibited from rotary motion relative to the polygonal shaft  31  of the differential assembly  3 . The lever  28  is coupled to a server through a linkage (not shown). The user can operate the remote controller to move the lever  28 , causing the movable gear  23  to be shifted axially along the polygonal shaft  31  of the differential assembly  3 , so as to force the external teeth  231  of the movable gear  23  into engagement with the internal gear  212  of the first gear  21  or the internal gear  222  of the second gear  22 . 
     As illustrated in FIG. 4, the first idle gear wheel  24  and the second idle gear wheel  25  are supported on a respective shaft between the first shell  20  and the second shell  20 A and meshed together for free rotation. The first idle gear wheel  24  is also meshed with the external teeth  211  of the first gear  21 . The second idle gear wheel  25  is also meshed with the external teeth  221  of the second gear  22 . 
     Referring to FIGS. 1,  2 , and  4  again, when the user drive the server and to move the movable gear  23  along the polygonal shaft  31  to the position shown in FIG. 2, the output power of the engine  10  is transmitted through the dual-gearshift position transmission mechanism  1  and the transmission tube  26  to the first gear  21 , causing the first gear  21  to be rotated clockwise. During clockwise rotation of the first gear  21 , the first idle gear wheel  24  and the second idle gear wheel  25  are driven to rotate the second gear  22  counter-clockwise. Because the internal teeth  222  of the second gear  22  are meshed with the movable gear  23 . The movable gear  23  is rotated with the second gear  22  counter-clockwise, thereby causing the polygonal shaft  31  of the differential assembly  3  to be rotated counter-clockwise. On the contrary, when moving the movable gear  23  to the position shown in FIG. 3, the external teeth  231  of the movable gear  23  are disengaged from the internal teeth  222  of the second gear  22  and meshed with the internal teeth  212  of the first gear  21 . At this time, clockwise rotation of the first gear  21  drives the movable gear  23  to rotate clockwise, thereby causing the polygonal shaft  31  of the differential assembly  3  to be rotated with the movable gear  23  clockwise. 
     Referring to FIG.  7  and FIGS. 1,  2  and  4  again, the differential assembly  3 , except the aforesaid polygonal shaft  31 , further comprises a first center axle  4 , a second center axle  41 , a plurality of first planet gears  33 , and a plurality of second planet gears  34 . The first center axle  4  and the second center axle  41  are axially coupled together, and can be rotated relative to each other. The polygonal shaft  31  is a tubular shaft of polygonal cross section, having an annular groove  311  around the periphery. After insertion of the polygonal shaft  31  through the center hole of the second gear  22  and the center hole of the movable gear  23 , a C-shaped clamp  27  is fastened to the annular groove  311  to secure the second gear  22  to the polygonal shaft  31 , enabling the movable gear  23  to be moved between the first gear  21  and the second gear  22 . The first center axle  4  is inserted through the polygonal shaft  31  and the transmission tube  26 , and can be rotated relative to the polygonal shaft  31  and the transmission tube  26 . The first center axle  4  and the second center axle  41  are respectively connected to different output systems. A first center axle gear  40  and a second center axle gear  410  are respectively fixedly mounted on the first center axle  4  and the second center axle  41 . The first planet gears  33  and the second planet gears  34  are mounted in a cover shell  32  in reversed directions. The first planet gears  33  are meshed with the second center axle gear  410 . The second planet gears  34  are meshed with the first center axle gear  40 . 
     When controlling the forward backward transmission control mechanism  2  to rotate the polygonal shaft  31  of the differential assembly  3 , the first planet gears  33  and the second planet gears  34  are turned around the second center axle gear  410  and the first center axle gear  41 , thereby causing the first center axle gear  40  and the second center axle gear  410  to rotate the first center axle  4  and the second center axle  41 , and therefore the first center axle  4  and the second center axle  41  synchronously give an output. At the same time, the first center axle gear  41  and the second center axle gear  410  are rotated on the respective axis, causing the first center axle  4  and the second center axle  41  to produce a speed difference. 
     The main feature of the present invention is to arrange the dual-gearshift position transmission mechanism  1 , the forward backward transmission control mechanism  2 , and the differential assembly  3  together, so that the remote control toy car has the advantages of high/low dual-gearshift position automatic shifting control, easy forward/backward steering control, impact structure, high economic effect, high performance, stable functioning, and etc. 
     FIG. 9 shows an alternate form of the present invention. According to this alternate form, the remote control toy car control system eliminates the aforesaid forward backward transmission control mechanism  2 , and directly couples the dual-gearshift position transmission mechanism  1  to the differential assembly  3 . As illustrated, the outer shell of the differential assembly  3  has an outer thread  36  threaded into the inner thread  261  of the transmission tube  26 . The transmission tube  26  is coupled to the dual-gearshift position transmission mechanism  1  in the same manner as the aforesaid first embodiment. By means of this arrangement, the output power of the dual-gearshift position transmission mechanism  1  is transmitted through the transmission tube  26  to the differential assembly  3 , causing the outer shell of the differential assembly  3  to be rotated with the transmission tube  26 . When rotating the differential assembly  3 , the planet gears  34  and  33  drive the first center axle gear  40  and the second center axle gear  410  to rotate, thereby causing the first center axle  4  and the second center axle  41  to provide a respective rotary output power differentially. 
     FIG. 11 shows another alternate form of the present invention. According to this alternate form, the remote control toy car control system is comprised of a dual-gearshift position transmission mechanism  1 A, a forward backward transmission control mechanism  2 , and a differential assembly  3 . The forward backward transmission control mechanism  2  and the differential assembly  3  are same as that of the embodiment shown in FIG.  1 . According to this embodiment, the dual-gearshift position transmission mechanism  1 A comprises a drive gear  1 A 01  coupled to the engine  1 A 0 , a driven gear  1 A 1 , a first transmission gear  1 A 2 , a clutch  1 A 3 , a second transmission gear  1 A 4 , an idle gear wheel  1 A 6 , and a one-way axle bearing  1 A 5 . 
     The first transmission gear  1 A 2  comprises a protruded block (not shown) suspended in the recessed front side thereof, a series of teeth  1 A 211  disposed around the periphery, and a two-way axle bearing  1 A 8  mounted in the center through hole thereof. The second transmission gear  1 A 4  comprises a series of teeth  1 A 41  disposed around the periphery and a one-way axle bearing  1 A 5  mounted in the center through hole thereof. The transmission tube  26  is inserted through the one-way axle bearing  1 A 5 , the clutch  1 A 3 , and the two-way axle bearing  1 A 8 , keeping the transmission tube  26  secured to the one-way axle bearing  1 A 5 , the clutch  1 A 3  and the two-way axle bearing  1 A 8 . The idle gear wheel  1 A 6  has a big gear  1 A 61  and a small gear  1 A 62  mounted thereon. A gear shaft  1 A 7  is inserted through the axial center through hole of the idle gear wheel  1 A 6  and connected between two opposite sidewalls of the outer shell of the dual-gearshift position transmission mechanism  1 A, keeping the big gear  1 A 61  meshed with the teeth  1 A 21  of the first transmission gear  1 A 2  and the small gear  1 A 62  meshed with the teeth  1 A 41  of the second transmission gear  1 A 4 . After installed in the outer shell of the dual-gearshift position transmission mechanism  1 A, the first transmission gear  1 A 2  has a part extended out of the outer shell of the dual-gearshift position transmission mechanism  1 A and fixedly connected to the driven gear  1 A 1 , which is meshed with the drive gear  1 A 01 . 
     Referring to FIG.  12  and FIG. 11 again, when starting the engine  1 A 0 , the drive gear  1 A 01  drives the driven gear  1 A 1  and the first transmission gear  1 A 2  to rotate, thereby causing the idle gear wheel  1 A 6  to rotate the second transmission gear  1 A 4 . By means of the effect of the one-way axle bearing  1 A 5 , the transmission tube  26  is rotated with the second transmission gear  1 A 4  at a low speed at this time. During rotary motion of the transmission tube  26 , the clutch  1 A 3  is rotated with the transmission tube  26  synchronously. When the speed of the engine  1 A 0  surpasses a predetermined level after starting, the centrifugal force produced from the rotary motion of the clutch  1 A 3  forces the movable stop element (not shown) of the clutch  1 A 3  outwards into engagement with the protruded block of the first transmission gear  1 A 2 , for enabling the driving power of the engine  1 A 0  to be transmitted through the driven gear  1 A 1  and the first transmission gear  1 A 2  to the transmission tube  26  to accelerate the speed of revolution of the transmission tube  26 . On the contrary, when the speed of the engine  1 A 0  drops below the predetermined level, the stop member of the clutch  1 A 3  is returned and disengaged from the first transmission gear  1 A 2 , enabling the driving power of the engine  1 A 0  to be transmitted through the first transmission gear  1 A 2 , the idle gear wheel  1 A 6  and the second transmission gear  1 A 4  to the transmission tube  26 , and therefore the transmission tube  26  is rotated at a low speed to provide a high torsional output. 
     A prototype of remote control toy car control system has been constructed with the features of FIGS.  1 ˜ 12 . The remote control toy car control system functions smoothly to provide all of the features discussed earlier. 
     Although particular embodiments of the invention have been described in detail for purposes of illustration, various modifications and enhancements may be made without departing from the spirit and scope of the invention. Accordingly, the invention is not to be limited except as by the appended claims.

Technology Classification (CPC): 5