Treadmill with improved adjusting mechanism

A speed adjusting mechanism for adjusting the speed of an endless belt of a treadmill includes a speed variable V-belt drive mechanism which has two pairs of cone-shaped discs mounted coaxially on a transmission shaft disposed between an output shaft of a motor and a driven shaft of the treadmill belt. Each pair of discs includes a fixed disc and a slideable disc adjacent to the slideable disc of the other pair of discs, and the slideable discs slide mutually upon lateral displacement of the transmission shaft. The transmission shaft is displaced laterally by a reversible motor through a crank mechanism and a gear mechanism including a sector gear. The slope of the belt is adjusted by another reversible motor through a gear mechanism including a sector gear.

BACKGROUND OF THE INVENTION 
This invention relates to a treadmill and particularly to adjusting 
mechanisms for adjusting the rotative speed and the slope of an endless 
belt of the treadmill. 
A machine denoted as a treadmill has been well known and widely used by 
many people. Today the treadmill is becoming increasingly popular as an 
exercise device due to the fact that the space for exercise activity in 
many cities is gradually decreasing. Ideally, this machine forces a person 
to move his or her legs at a rate which will prevent the person from being 
thrown off the exercise device. Typical exercise machines, of course, 
employ a complicated structure; however, such structure is either 
inaccessible or difficult to manipulate immediately, so as not to fulfill 
the requirements of the user. 
It is known to provide adjusting mechanisms for adjusting the rotative 
speed and the slope of an endless belt of the treadmill. One of the known 
treadmill includes an adjusting mechanism which has a V-belt drive 
assembly operated by a reversible motor through a gear assembly. The 
V-belt drive assembly includes a pair of cone-shaped discs, one of the 
pairs being mounted on an output shaft of a driving motor and the other 
pair being mounted on a transmission shaft parallel to the output shaft. 
The pair of the discs mounted on the transmission shaft has a slideable 
disc which can be moved toward and away from an adjacent fixed disc by the 
operation of the reversible motor and a telescopic threaded sleeve which 
is extensible and retractable to move the slideable disc. The transmission 
shaft is associated operably with the driven shaft of the belt through a 
complicated gear assembly. The slope adjusting mechanism of this treadmill 
includes a linkage system which can be adjusted in height through a screw 
adjustment unit. 
SUMMARY OF THE INVENTION 
The main object of this invention is accordingly to provide an improved 
speed adjusting mechanism for the belt of a treadmill. 
Another object of this invention is to provide an improved treadmill 
adaptable to adjust the slope of the belt easily. 
This invention provides an improved speed adjustable driving mechanism 
which comprises: a driving motor having an output shaft; a driven shaft 
associated with the endless belt; a speed variable V-belt drive mechanism 
in connection with the output shaft and the driven shaft, the belt drive 
mechanism including a transmission shaft which is parallel to the output 
shaft and the driven shaft therebetween and which can be displaced 
laterally within a limited distance toward the output shaft or the driven 
shaft, two pairs of cone-shaped discs mounted coaxially on said 
transmission shaft, each of the pairs of the discs having a fixed disc and 
a slideable disc adjacent to the slideable disc of the other pair of the 
discs, the slideable discs sliding mutually upon displacement of the 
transmission shaft, a first pulley mounted on the output shaft, a second 
pulley mounted on the driven shaft, a first belt passing over said first 
pulley and one of the pair of discs, and a second belt passing over said 
second pulley and the other pair of discs; and means for displacing the 
transmission shaft, including a crank shaft in parallel with the 
transmission shaft, a crank arm interconnecting the transmission shaft and 
the crank shaft, a first reversible motor for driving the crank shaft, and 
a gear transmission mechanism interengaging the crank shaft and the first 
reversible motor. 
The invention also provide a slope adjusting mechanism which includes: a 
pair of legs connected pivotally to a bottom side of the first portion of 
the base frame, a second sector gear having an arm operably associated 
with the legs and a curved toothed portion extending upwardly from the 
arm, a second reversible motor mounted on the first portion, a second 
gearing mechanism interengaging the second reversible motor and the second 
sector gear to hold adjustably the legs in a position forming an angle 
with the base frame and to move the second sector gear so as to vary the 
angle of the legs relative to the base frame.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
FIG. 1 shows this invention as associated with a treadmill 1 having a base 
frame 2 on which an endless belt 3 is rotatably mounted. The base frame 2 
has a pair of integral upright posts 4 secured thereto. An instrument 6 
which has a display and a plurality of functions thereon for readily 
manipulating this machine and instantaneously realizing the status of the 
user himself, is mounted integrally between the upper ends of the posts 4 
and a handle portion 5 is secured thereto. 
FIG. 2 shows a speed adjustable mechanism 10 mounted within the first 
portion of the base frame 2 for driving the endless belt 3 at a variable 
speed, including a drive motor 11 having an output shaft 111; a driven 
shaft 15 associated with the endless belt 3; a speed variable V-belt drive 
mechanism in connection with the output shaft 111 and the driven shaft 15, 
the belt drive mechanism 12 including a transmission shaft 123 which is 
parallel to the output shaft 111 and the drive shaft 15 and which can be 
displaced laterally, pulleys 112 and 151 mounted respectively on the 
shafts 111 and 15, two pairs of cone-shaped discs 121 and 122 mounted 
coaxially on the transmission shaft 123, each of the pairs of discs 121 
and 122 having a fixed disc 121' or 122' and a slidable disc 121" or 122" 
adjacent to the slidable disc of the other discs, the slidable discs 121" 
and 122" sliding mutually upon displacement of the transmission shaft 123; 
and means 13 for displacing the transmission shaft 123, including a crank 
shaft 133 in parallel with the transmission shaft 123, a crank arm 131 
interconnecting the transmission shaft 123 and the crank shaft 133, two 
seats 134 and 135 for mounting the crank shaft 133; a first reversible 
motor 14 for driving the crank shaft 133, and a gear transmission 
mechanism interengaging the crank shaft 133 and the first reversible motor 
14. 
The gear transmission mechanism includes a first sector gear 132 mounted on 
the crank shaft 133 and a first worm wheel 143 engaging with the sector 
gear 132, a gear 142 engaging with a gear 141 mounted on the first 
reversible motor 14. 
The fixed discs 121' and 122' and the slidable discs 121" and 122" are 
substantially in the same configuration. Referring to FIGS. 3, 4 and 5, 
each disc 121', 122', 121" and 122" includes a truncated cone-shaped 
surface having a plurality of angularly spaced engagement grooves 124 
adjacent directly to a central through-bore 126 and extending radially on 
the surface. The slideable discs engages with the respective fixed discs 
by means of these engagement grooves when they approach the fixed discs. 
FIGS. 6A and 6B show the speed adjustable mechanism 10 in operation. Belts 
16 and 17 are arranged to pass over the pulleys 111, 151 and the pairs of 
the discs 121 and 122. The slideable discs 121" and 122" are urged towards 
the fixed disc 122' over the force exerted by the belt 16 and the disc 
122" is engaged with the disc 122' by means of the grooves 124 when the 
motor 14 is operated to cause the shafts 133 and 123 to be aligned 
horizontally as shown in FIG. 6A. This action results in an increased 
distance between the transmission shaft 123 and the belt 17, thereby 
increasing the speed of the driven shaft 15. When the shaft 123 is moved 
downward relative to the shaft 133, the rotative speed of the shaft 15 is 
decreased due to the operation of the belts 16 and 17 and the discs 121 
and 122 as shown in FIG. 6B. 
FIGS. 7, 8 and 9 show a slope adjustable mechanism 22 mounted below the 
base frame 1 to vary the slope of the base frame 2, which includes a pair 
of legs 222 and 223 connected pivotally to the first portion of the base 
frame 2 by means of a pivot shaft 221, a second sector gear having an arm 
224a mounted together with the leg 223 and a curved toothed portion 224 
extending upwardly from the arm; a second reversible motor 21; a second 
gear mechanism including worm wheels 211, 212 to interengage the second 
reversible motor 21 and the second sector gear 224 so as to move the 
second sector gear 224 and holds adjustably the legs 222 and 223 in an 
inclined plane relative to the base frame 2. 
When the sector gear is moved upwardly by operating the motor 21, the slope 
of the base frame 2 decreases. On the contrary, when the sector gear is 
moved downward as shown in FIG. 9, the slope increases. 
While a specific embodiment of the invention has been shown and described 
in more detail to illustrate the application of the principles of the 
invention, it will be understood that the invention may be embodied 
otherwise without departing from the spirit and scope of this invention.