AN IMPROVED MOTORIZED TREADMILL SPEED CHANGER

Abstract: An improved motorized treadmill speed changer, especially one which changes speed by dry friction, characterized by com­ prising an adjusting unit consisting of a handle bar (11), a pinion (12), a rack (14), a motor base slide and a U support (18), and a driving unit consisting of a motor (40), a friction cone (21) and a friction wheel (22), and being constructed in such way that the speed of the revo­ lving belt (50) of the motorized treadmill can be changed steplessly and controlled by turning the handle bar (11).

Description: There are two kinds of speed changers of conventional motorized treadmills. One changes the speed of the treadmill by adjusting the distance between the belt pulleys on the motor shaft and the treadmill roller. Obviously, this kind of speed changer has the following disadvantages : (1) Without the help of another person, it is impossible for the operator to turn the screw rod when running. (2) It needs a motor of greater power, namely, it consumes more electricity. (3) Its motor can not be started loadlessly because it has no separating mechanism. So elastic fatique and slip will occur to the belt after being in tension for a long time and adjusted frequently. As a result, the life of motor and belt will be reduced. (4) It is not suitable for use by old people and patients who are recovering from illness because it can not be started from zero speed. Another changes the speed of the treadmill by changing its voltage. This kind of motorized treadmill can be started from zero speed but the structure is too complicated. The need of motor of greater output results in higher consumption of electricity and the high cost of construction reduces its competitiveness. In view of these disadvantages, the inventor tried hard to make improvements and developed the improved motorized treadmill speed changer which can be started from zero speed and change speed steplessly and freely. So the main object of this invention is to provide an improved motorized treadmill speed changer of which the speed of the revolving belt can be changed easily by adjusting the engaging point of a friction cone on a motor shaft and a friction wheel on the roller of the treadmill. Another object of this invention is to provide an improved motorized treadmill speed changer which has a greater speed range and is suitable for use by people of different physical conditions. Still another object of this invention is to provide an improved motorized treadmill speed changer which can be started from zero speed and reach a speed as high as 1:1 (1 rotation of the motor shaft to 1 rotation of the roller of the tread-mill). Still another object of this invention is to provide an improved motorized treadmill speed changer of which the motor is of smaller power and is carried by a slide on a U support so that the cost of the treadmill can be reduced. Before describing the present invention in detail, attention is first directed to US-A-3 737 163 that discloses an exercising machine comprising an endless belt that can be caused to move at varying speeds and on which people can walk. It comprises a fixedly positioned drive motor on the shaft of which is mounted a first friction wheel the axis of which lies in a horizontal plane and is directed in the longitudinal direction of the belt, i.e. normal to a driven roller about which the belt is tensioned. The machine comprises a second friction wheel mounted on a shaft that is parallel to the axis of said driven roller. The second friction wheel is slidable back and forth along its shaft but remains in driving relationship therewith, there being an endless chain that couples a sprocket wheel fixed on said shaft to a sprocket wheel fixed to said driven roller, so that said second friction wheel drives said driven roller. The plane of the second friction wheel is normal to the plane of the first friction wheel, with the periphery of the second friction wheel being in engagement with a flat radially extending face of the first friction wheel. By moving the second friction wheel along its shaft the speed of the travelling belt can be varied. A further prior art that is of interest is DE-C-811 6456 that discloses a drive unit comprising a motor on the shaft of which is a friction cone. The unit includes a friction wheel mounted rigidly on a shaft that is parallel to the shaft of the motor, said friction wheel being in engagement at its periphery with the friction cone to be driven thereby. The drive unit includes a mounting means that enables said friction wheel to be displaced back and forth along a path parallel to the inclined surface of the friction cone so that the speed of said friction wheel can be varied. Summary of the present invention The present invention is as defined in the accompanying claims, Claim 1 of which has been divided into a two-part form based on the assumption that US-A-3 737 163 is the nearest state of the art. Brief description of the drawings Fig. 1 is a vertical view of the improved motorized treadmill speed changer of this invention. Fig. 2 is a top view of the said speed changer. Fig. 3 is a sectional view of the said speed changer. Fig. 4 is an exploded view of the adjusting unit of the said speed changer. Fig. 5 illustrates the friction work of the friction wheel and friction cone of the said speed changer. Detailed Discription of the Preferred Embodiment As shown in the drawings, the improved motorized treadmill speed changer of this invention comprises an adjusting mechanism 10 and a driving mechanism 20. The adjusting mechanism 10 consists of a handle bar 11, a pinion 12, a rack 14, a motor base slide 13 and a U support 18. The handle bar 11 and the pinion 12 is pivotally mounted on the frame 30 of the motorized treadmill. The rack 14 has two slide bars 16, 17 in both sides and is diagonally fixed to the frame 30 of the motorized treadmill. The rack 14 has two slide bars 16, 17 slidably fitted in the slot ways 19. The motor base slide 13 has two transverse holes to be fitted on the slide bars 16, 17. When the handle bar 11 and the pinion 12 is turned clockwise the engaged rack 14 and the motor base slide 13 with the motor 40 thereon will move forward and vice versa. The driving mechanism 20 consists of a motor 40 mounted of the base slide 13, a friction cone 21 fixed to the shaft of the motor 40, and a friction wheel 22 fixed to the roller 31 of the endless belt of the motorized treadmill. The friction wheel 22 is covered with a layer of colloid material 221 to act as a buffer to prevent slipping when the friction wheel 22 is driven by the friction cone 21. Sinc the curved surface of the friction cone 21 tapers evenly to the apex, the speed of friction wheel 22 reduces with the contact point moving toward the apex. In other words, the speed of the friction wheel 22 is fastest when the friction wheel 22 engages the base of the friction cone 21 and slowest when the friction wheel 22 engages the apex of the friction cone 21. In order to attain best friction and eliminate the stress resulting from friction, the adjusting mechanism 10 and driving mechanism 20 are so arranged that the line between the circumference of the base and the apex of the friction cone 21 is in alignment with the inner rim of the friction wheel 22 and parallel to the side of the U support 18. When the friction cone 21 disengages the friction wheel 22, the endless belt 50 of the treadmill can be pushed in a revolving manner by the operator who treads the mill. When the handle bar 11 and the pinion 12 is turned clockwise, the friction cone 21 on the motor shaft will advance with the forward movement of the rack 14 and slide 13 to engage the friction wheel 22. At this time, the endless belt 50 of the treadmill is driven by the motor. The speed of the revolving belt 50 increases with the advancing of the friction cone 22 and decreases with the retreating of the same. So the speed of the revolving belt can be changed steplessly and controlled by turning the handle bar 11.

Claims: A motorized treadmill speed changer comprising an adjusting unit and a driving unit; said driving unit comprising a motor (40) driving a friction member (21); said adjusting unit comprising a friction wheel (22) driven by said friction member (21); said friction wheel (22) driving a roller (31) about which an endless belt (50) of the treadmill extends to be driven thereby; and means for varying the speed of said belt (50) by varying the location at which there is a driving contact between said friction member (21) and said friction wheel (22); characterized in that; said adjusting unit consists of a handle bar (11), a pinion (12) connected to the handle bar (11) and pivotally mounted on the frame (30 of the tread-mill, a U support (18) having two slot ways (19), one in both side walls of the U-support, and being diagonally fixed to the frame (30) of the treadmill, a rack (14) having two slide bars (16, 17) slidably fitted in the slot ways (19) and a motor base slide (13) having two holes (20) fitted on said slide bars (16, 17) said driving unit consists of said motor (40) being mounted on said base slide (13); that said friction member (21) is a friction cone (21) fixed to the shaft of the motor (40), and that said friction wheel (22) is fixed to said roller (31) and is covered with a layer of colloid material (221) to act as buffer to prevent slipping; said two units being so constructed that the line between the circumference of the base and the apex of the friction cone (21) is in alignment with the inner rim of the friction wheel (22) and parallel to the side of the U support (18) so as to attain best friction and eliminate stresss resulting from friction and that the slide (13) and the motor (40) with the friction cone (21) can be pushed back and forth by turning the handle bar (11) and the speed of the revolving belt (50) increases with the advancing of the friction cone (21) and decreases with the retreating of the same so that the speed of the revolving belt (50) can be changed steplessly and controlled by turning the handle bar (11). A motorized treadmill speed changer according to Claim 1 wherein the friction cone (21) mounted motor shaft and the friction wheel (22) mounted treadmill roller (31) are on the same horizontal plane and the friction cone (21) keeps contact with the rim of the friction wheel (22) so as to achieve good transmission.

Inventors: LIN, PAUL
Applicants: LIN, PAUL
Application year: 1989
Main classification: A63B22
IPC codes: A63B22