Actuator for controlling inclination of treadmill and inclination control device of treadmill

Abstract

The present invention provides an inclination control device of a treadmill comprising: a pair of support members pivotally connected with at least one first hinge at the track part for extending from the track part to the ground; a pair of housings having a housing hinge respectively for being pivotally connected with each of the second hinge at the support members, and having female thread; a pair of screw rod engaging respectively with the female thread of each of the housing so as to be extruded from or inserted into by relative rotation therebetween; a pair of driving pulleys combined with each of the screw rod for rotating together with the screw rod; a belt engaging with the driving pulleys; a pinion engaging with the belt for transmitting a driving force via the belt to the driving pulleys; a motor for letting pinion rotate; and a bracket for rotatably fixing the pinion and the driving pulleys, and having a pair of bracket hinges on its both sides to be pivotally combined with each of the third hinges of the track part, whereby the first hinge, the second hinge and the third hinge form a three-linked structure so as to stably support the impact and/or load from a user's running in addition to enhance durability and to save the manufacture cost.

Description

BACKGROUND

1. Field of the Invention

The present invention relates to a treadmill, more particularly, to an actuator for stably controlling an inclination of the track part of a treadmill and an inclination control device of a treadmill.

2. Discussion of Related Art

A treadmill known as a running machine is widely used indoors such as at home or in a sports center because it allows a user to effectively exercise by working or running on its endlessly rotating track belt even in the narrow space. In view that a user can exercise indoors using treadmill even in the cold winter, the demand for treadmills is recently drastically increasing due to the advantages of its safety and convenience because.

By using a treadmill, the user thereof can strengthen the cardiopulmonary function and muscles of legs, and can control weight by consuming calories efficiently while running or walking on the treadmill. To maximize this exercise effect, a treadmill with an inclination control device came to be lately produced.

More specifically, a treadmill generally comprises a track part on which user put their feet for running or walking, and an inclination control device for supporting the track part and to control the inclination.

As illustrated in FIGS. 1 and 2, the conventional treadmill comprises a track part 10 on which user run or walk, a support part 20 located at a bottom of the treadmill for controlling the inclination of the track part 10 while sustaining the load or impact transmitted from the track part 10.

The track part 10 has a support frame 11 which upholds weight of user; a belt rotating endlessly, which enables a user to run or walk continuously on the upper side of the track part 10; a pair of rollers 13 supporting both sides of the belt 12; a motor 14 as a driving unit for driving making one of the rollers 13 rotate; and connection part 15 linked with the actuator 30.

The support part 20 includes a base frame 21 installed on the ground, and a support member 22, having its one end fixed to a base frame 21 and the other end 22a pivotally connected to a track part 10.

The actuator includes a extendable rod 32, of which one end 32a is pivotally connected to a link member 15 of the track part 10, and of which the other end is pivotally connected to a base frame 21; and a driving part 31 to control the length of the extendable rod 32 by extending or contracting the extendable rod 32.

The above conventional treadmill controls its inclination of the track part 10 by means of extending or contracting the extendable rod in the direction of 30a. In this case, the load or impact of user is concentrated on the part where user put their foot apart from the other end 22a of a fixed member by d1. That is, The load and/or impact is concentrated on the front part of the track part 10, and thus the load Fa of the actuator 30 will be obtained by the following equation in condition that the track part 10 is parallel to the ground. Fa′=F  Equation 1

In general, since d2 is designed smaller than d1, the load Fa′ applied on the actuator 30 is calculated by user's load F₁ amplified by d1/d2. Besides, the actuator get more moment due to user's load F₁ generated from exercise on the track. The conventional treadmill accordingly needs a big actuator to endure the load and it result in an unnecessary increase of manufacture costs and power consumption.

Also, it is not desirable to install a big actuator in the narrow space between a track part 10 and a base frame 21, from view that a user feels safe when the distance between the base frame 21 and the track part 10 is as short as possible. As a solution for this problem, it can be considered that the actuator 30 is installed at both sides of the track part as a pair. However, if two actuators 30 are not exactly controlled with the same extended or the same contracted length, it causes to have a problem that track part 10 is widthwise inclined even by the small amount, whereby the user feels unstable and uncomfortable.

SUMMARY OF THE INVENTION

The present invention has been made in view of the above and/or other problems, and it is an object of the present invention to provide with an actuator for controlling an inclination of the track part of a treadmill, which is capable of stably controlling the inclination of the track part by simultaneously contracting or simultaneously extending a pair of extendable rods.

Another object of the present invention is to provide an inclination control device of a treadmill, which minimizes the load and moment on the extendable rod of the actuator for controlling the inclination of the treadmill thereby enhancing durability as well as efficiently reducing the manufacturing cost.

In order to achieve the above objects and another aspect of the present invention, the present invention provides an actuator for controlling the inclination of the track part of a treadmill comprising: a driving unit; a pinion rotatably driven by the driving unit; a belt formed to transmit the driving force from the pinion; a pair of driving pulleys engaging with the belt so as to receive the driving force from the pinion; a pair of screw rod combined with each of the driving pulley for rotating together with each of the driving pulley; and a pair of housings having female thread for engaging with each of the screw rod, whereby a pair of screw rods are simultaneously extruded from or simultaneously inserted into each of the housing by the same length.

This is intended to control a pair of extendable rods including the screw rods and the housings to be extended or contracted by the same amount based on that the driving force from the driving unit is transmitted via the belt to a pair of the driving pulleys so that a pair of the driving pulleys rotates by the same amount.

Herein, at least one idler pulley engaging the belt is additionally included thereby obtaining the higher wrapping angle of the pinion surrounded by the belt. Therefore, the friction between the pinion and the belt is increased, and the driving force can be transmitted to a driving pulley without any loss.

Periodical grooves are formed on the outer sides of the pinion, the idler pulley and the driving pulley, and also, the periodical protuberances engaged with the grooves are formed so as to thoroughly remove any slip between the belt and the pulleys due to the increase of the friction, thereby precisely controlling the screw rod's displacement.

It is effective to further comprising: a bracket for rotatably fixing the pinion, the idler pully, and the driving pulleys as one module; bracket hinges formed on both end sides the bracket to be pivotally combined with the track part of a treadmill; and housing hinges formed at each of the housings, whereby the actuator can be easily combined with a treadmill which realizes stable control of the inclination of the track part.

Meanwhile, the actuator for controlling the inclination of a treadmill can use chain or gear instead of the belt as a power transmission means in order to embody the same function.

That is, the treadmill can comprise a driving unit; a pinion rotatably driven by the driving unit; at least one pair of intermediate gear formed to transmit the driving force from the pinion; a pair of driving gears engaging with the intermediate gears so as to receive the driving force from the pinion; a pair of screw rod combined with each of the driving gear for rotating together with each of the driving gear; and a pair of housings having female thread for engaging with each of the screw rod, whereby a pair of screw rods are simultaneously extruded from or simultaneously inserted into each of the housing by the same length.

Herein, the intermediate gears can be plural at one side between the pinion and the driving pulley because it is necessary to install the driving pulleys apart from the pinion in the narrow and long bracket.

On the other hand, the present invention provides with an inclination control device for a treadmill having at least one track part comprising: at least one extendable rod pivotally connected with at least one second hinge which moves together with the support member, and pivotally connected with a third hinge of the track part which is located apart from the first hinge at the track part; wherein, the inclination of the track part is controlled by the extension or the contraction of the extendable rod.

That is, the first hinge, the second hinge and the third hinge form three-link structure, thereby securely support the track part. Although the actuator is located in the front area of the track belt on which user put their feet, as the load and/or impact from a user is not concentrated on the screw rod of the actuator because three elements (i.e., the track part, the support member, and the screw rod with the housing) make up a three-link mechanism, the screw rod can be designed to be smaller diameter or to be a smaller size for obtaining the required durability, thereby realizing the small-sized actuator and saving the manufacturing cost.

It is desirable to include a traverse member to connect between a pair of the support members for obtaining stability.

Also, the second hinge is located at the traverse member so as to easily pivotally combine the extendable rod (more specifically, housing) with the traverse member, thereby achieving the lower manufacturing cost.

It is effective for each roller to be attached at the end of the support members contacted with the ground, thereby reducing friction between the support member and ground when the inclination of the track part is controlled.

When the length of the support member is assumed as L, it is desirable that the second hinge is located in 0.1 L or 0.5 L from one end of the support member contacted with ground. It means that the second hinge is formed near to ground so as to reduce the load applied on the screw rod.

The gear can be used as a means of transmitting power from the drive unit for controlling the inclination of the treadmill.

BRIEF DESCRIPTION OF THE DRAWINGS

These and/or other objects and advantages of the invention will become apparent and more readily appreciated from the following description of preferred embodiments, taken in conjunction with the accompanying drawings of which:

FIGS. 1 and 2 are views illustrating an inclination control device of a conventional treadmill, in which:

FIG. 1 is a side view illustrating a structure of inclination control device of treadmill;

FIG. 2 is a side view showing the reaction force on the inclination control device of FIG. 1 as a user exercises thereon;

FIGS. 3 to 7 are views illustrating an actuator for controlling an inclination of the track part of the treadmill in accordance with one embodiment of the present invention;

FIG. 3 is perspective views of part of the actuator when the extendable rod thereof is contracted.

FIG. 4 is perspective views of part of the actuator when the extendable rod thereof is extended.

FIG. 5 is a perspective view of the actuator adding a hinge bracket into the part of the actuator of FIG. 3;

FIG. 6 is a perspective view of the actuator from another view;

FIG. 7 is a plane view of FIG. 5;

FIG. 8 is a schematic view illustrating a structure of an actuator for controlling an inclination of the track part of the treadmill in accordance with another embodiment of the present invention;

FIGS. 9 to 12 are views illustrating an inclination control device using the actuator shown in FIG. 5 for a treadmill in accordance with one embodiment of the present invention;

FIG. 9 is a perspective view illustrating the treadmill when the inclination of the track part is high position;

FIG. 10 is a perspective view illustrating a structure of the treadmill when the inclination of the track part is low position;

FIG. 11 is a perspective view illustrating a structure of treadmill without a driving cover when the inclination of the track part is low position;

FIG. 12 is a side view of the treadmill shown in FIG. 10; and

FIG. 13 is a FIG. to explain the three-linked truss structure for diverging the load from walking or running of a user.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

Hereinafter, an actuator for controlling an inclination of a treadmill according to a preferred embodiment of the present invention will be described.

As illustrated in FIGS. 3 to 7, the actuator 130 for controlling the inclination of a treadmill in accordance with one embodiment of the present invention comprises a driving unit for generating and transmitting the driving torque; and a pair of extendable rod 140 which can be extended or contracted in its length by using the power transmitted from the driving unit.

The driving unit has an actuator motor 131 generating rotating force; a transmission 132 for reducing the rotating speed of a actuator motor 131; a pinion 133 rotatably combined with the transmission 132; a belt 137 to transmit rotating power via the pinion 133; driving pulleys 135, 136 rotatably installed by the power transmitted from the pinion via the belt 137, an idler pulley 134 rotatably installed for changing the path of the belt 137 between the pinion 133 and driving pullys 135, 136 so as to increase the wrapping angle of the pinion 133; the belt 137 transmitting the driving force from the pinion 133 to the driving pulley 135, 136; a bracket 138 rotatably fixing the pinion 133, idler pulley 134, and driving pulleys 135, 136 for forming them as one module; a pair of protuberances 138a at both end sides of the bracket 138 to be pivotally combined with the track part 110 of the treadmill 100; and a fixing plate 139 on a low side of the bracket 138 for fixing the transmission 132.

In order to prevent the slip between the belt 137 and pulleys (including pinion 133, idler pulley 134 and a pair of driving pulleys 135, 136), although not shown in the Figures, it is effective that grooves are periodically formed at outside of the pulleys 133, 134, 135, 136, and that protuberances for engaging with the grooves respectively are periodically formed at one side or at both sides of the belt 137. A commercially used V-groove type belt having protuberances on its one side can be applied thereto through twisting the belt by 180 between the pinion 133 and the idler pulley 134 and between the idler pulley 134 and the driving pulley 135.

Also, as shown in FIGS. 3 to 5 and 7, by the installation of the idler pulley 134 in the bracket 138 for changing the path of the belt 137, the wrapping angle of the pinion 133 is increased more than 180° so that precise control of the rotation angle of the driving pulleys 135, 136 can be realized by the increase of the driving friction therebetween.

A pair of the extendable rod 140 rotates together with each of the driving pulleys 135, 136 fixed to the upper end thereof. Each extendable rod 140 includes a screw rod 142 having thread on its whole length, and a housing 141 having female thread for engaging with the thread of the screw rod 142, and thus, each extendable rod 140 can become longer when the screw rod 142 is extruded from the housing 141 by relative rotation therebetween, and become shorter when the screw rod is inserted into the housing 141.

Herein, a hinge hole 141a as a housing hinge is formed at the low end of the respective housing 141 for being pivotally combined with each of second hinges 141a of the track part 110. In order for the driving pulleys 135, 136 and the bracket 138 integrally move together, the bracket 138 is fastened by nuts 142b. That is, groove is formed between the nut 142b and the driving pulleys 135, 136 in the direction of circumference and the bracket 138 is inserted within the groove 142a.

The drawing notation of 132a is a bearing installation part supporting rotation of a rotating axis 132b to connect the transmission 132 and a pinion 133, and the drawing notation of 139a is a bolt to fix the fixing plate 139 to the bracket 138.

Hereinafter, operation principle of the actuator 130 in accordance with one embodiment of the present invention is explained.

When the actuator motor 131 rotates in order to drive the contracted extendable rod 140 to be extended as illustrated in FIG. 5, the driving torque is transmitted from the actuator motor 131 to the pinion 133, and the pinion 133 is driven to rotate counterclockwise. Accordingly, an idler pulley 134 connected by the belt 137 with the pinion 133 is driven to rotate clockwise, and simultaneously, a pair of driving pulleys 135, 136 is driven to rotate counterclockwise. As one end 141a of the housing 141 is fixed to other component such as a support member 151 or a traverse member 153, the housing 141 is restricted not to rotate any longer. Thus, as the driving pulley 135, 136 are driven rotate counterclockwise, a pair of the screw rods 142 accordingly rotate together with the pulleys 135, 136 at the same angle, and thus, a pair of screw rods 142 is to be upwardly (142c) extruded from the housing 141 by the same length each other, whereby the length d of the extendable rod become longer as shown in FIG. 5.

Similarly, when the actuator motor 131 rotates in order to drive the extended extendable rod 140 to be contracted as illustrated in FIG. 3, the driving torque is transmitted from the actuator motor 131 to the pinion 133, and the pinion 133 is driven to rotate clockwise. Accordingly, an idler pulley 134 connected by the belt 137 with the pinion 133 is driven to rotate counterclockwise, and simultaneously, a pair of driving pulleys 135, 136 is driven to rotate clockwise. As one end 141a of the housing 141 is fixed to other component such as a support member 151 or a traverse member 153, the housing 141 is restricted not to rotate any longer. Thus, as the driving pulley 135, 136 are driven rotate clockwise, a pair of the screw rods 142 accordingly rotate together with the pulleys 135, 136 at the same angle, and thus, a pair of screw rods 142 is to be downwardly (142d) extruded from the housing 141 by the same length each other, whereby the length d of the extendable rod become shorter as shown in FIG. 3

In the above manner, the actuator 130 can precisely control the length of a pair of the extendable rod simultaneously.

It is also possible that the actuator for controlling the inclination of the treadmill of the present invention can drive as a manner of transmitting power from a motor to a screw rod of the extendable rod using plural gears as shown FIG. 8.

Hereinafter, details of another embodiment of the present invention including plural gears will be explained.

As illustrated in FIG. 8, an actuator 230 for controlling the inclination by using gears for transmitting the driving torque comprises a driving unit generating the driving torque, and a pair of extendable rods 140 of which length are contracted and extended by the driving torque transmitted from the driving unit. Herein, in order to clarify this embodiment, an explanation of the detailed structure described above on the extendable rod 140 is omitted as it is identical or similar to the foregoing embodiment.

The driving unit includes The driving unit has an actuator motor 131 generating rotating force; a pinion gear 233 rotatably driven by the actuator motor 131; intermediate gears 234, 234′, 234″ engaging the pinion gear 233; a pair of driving gears 235, 236 fixed to rotate together with a screw rod 142 engaging the intermediate gears 234-234″ and a bracket 138 formed for rotatably fix the gears 233, 234, 234′, 234″, 235, 236 as one module.

In case that the pinion gear 233 is located in the center of bracket 138, it is possible to arrange intermediate gear 126 symmetrically. However, in the case that the pinion gear 233 is not located in the center of bracket 138, such is not possible. For example, as shown in FIG. 8, when the pinion gear 233 is placed left from the center, one intermediate gear 234 is installed between the pinion gear 233 and left driving gear 135, while three gears 234, 234′, 234″ are installed between the pinion gear 233 and right driving gear 136. That is, it is not needed to set up the same number of left and right gear and it is enough to balance the number of the teeth of gears to be engaged each other. When the number of left and right gears is different, a moving direction of left and right screw rods 142 can be matched by means of balancing the number of intermediate gear. That is, when the number of one side of intermediate gear 234 is odd, that of the other side of intermediate gears 234-234″ should be odd, and when the number of one side of intermediate gear 234 is even, that of the other side of intermediate gears 234-234″ should be even.

Hereinafter, operation principle of the actuator 230 in accordance with another embodiment of the present invention is explained.

In order to control the length of the extendable rod 140, as a actuator motor 131 is driven to rotate, a pinion gear 233 also rotates interlocked with the actuator motor 131. Thus, one or several intermediate gears 233, 233′, 233″ engaged with the pinion gear 233 also rotate in the opposite direction, and the driving pulleys 235, 236 engaged with intermediate gears 234 is also driven rotate. According to the rotation of the driving gears 235, 236, a pair of the screw rod 142 fixed to the driving gears 235, 236 respectively move up and down by being extruded from or being inserted into the housing 141 so that the length of extendable rod 140 can be contracted or extended.

Furthermore, the mechanism of power transmission in accordance with one embodiment of the present invention is not limited to the above described belt system as well as the gear system. The scope of the present invention includes a power transmission by driving the driving means such as driving pulleys 135, 136 with a chain system, and also includes the construction of which extendable rod comprises a rack gear engaging driving gears 235, 236.

On the other hand, the present invention provides with an inclination control device of treadmill using the above actuator for controlling the inclination of a treadmill. Hereinafter, details of an inclination control device of a treadmill in accordance with one embodiment referring to FIGS. 9 to 13.

FIG. 9 is a perspective view illustrating the treadmill when the inclination of the track part is high position, and FIG. 10 is a perspective view illustrating the structure of treadmill without the driving cover shown in FIG. 9. The treadmill 101 with the inclination control device in accordance with one embodiment of the present invention comprises a track part 110 on which user run or walk; a track driving unit 120 for driving the track belt 112 to rotate endlessly of the track part 110; an inclination control device to control the inclination of the track part 110 by including the actuator 130, the extendable rod 140 and a front support 150 to uphold the track part 110 with controlling the inclination thereof; a rear support 160 to uphold a rear part of the track part 110; and a column part 170 vertically protruded from the track part 110.

The track part 110 includes a main bracket 111 to cover the bottom side of the track part 110; a footplate (not shown) installed in the main bracket to uphold the load of user; a support frame (not shown) installed in the main bracket to support the footplate; a track belt 112 installed to cover the upper and lower sides of the footplate for endlessly rotating; a side cover 113 to cover both sides of upper part of the main bracket 111; a plate 114 fixed to the upper side of the front part of the main bracket 111 and having a hinge hole 114a to be pivotally combined with each of the protuberance 138a of the bracket 138 of the actuator shown in FIG. 4; a first hinge plate 115 located at the lower side of the main bracket 111 to pivotally combined with the end of the support member 151; a fixing plate 116 located at the upper side of the main bracket 111 for easily combining the column part 170.

The track driving unit 120 includes a track driving motor 121 generating the rotating power driving the track belt 112 of the track part 110, a connection belt 122 transmitting power of the track driving motor 121, a driving roller 123 connected with the connection belt for being driven to rotate by the track driving motor 121, an idler roller 124 located at the rear part of the track part 110, and a driver unit cover 125 for preventing the undesirable dusts or particles from entering into the track driving motor 121.

The front support 150 includes a pair of support members 151 pivotally connected to each of the first bracket 115 located at both sides of the lower part of track part 110, a roller 152 rotatably combined with the end of each of the support member 151 so that the end of the support member 151 can smoothly slide against the ground. And the support member 151 includes a traverse member 153 to connect the both support members 151 each other. Herein, a first hinge 151a is formed at the pivotally connected point between the support member 151 and the first bracket 115 of the track part 110.

The rear support 160 has contact portions made of rubber material for preventing the unexpected slide between the rear support 160 and the contact portion.

The column part 170 includes a column 171 upwardly stretching from the track part 110 by combining with the fixing plate 116, a handle attached to the other end of column 171, and a control panel 173 combined with the end of the handle for inputting the exercise program and displaying exercise information.

The inclination control device includes the actuator 130 for simultaneously controlling the length of the extendable rod 140 by the same amount, the expandable rod 140 as described above, and a front support 150 for upholding the front part of track part 110.

The actuator 130 is structured as illustrated in FIG. 3 or FIG. 7 and above mentioned. How to install the actuator 130 in a treadmill is as follow.

As illustrated in FIG. 13, an inclination control device of treadmill of the present invention can efficiently prevent its members 110, 151, 141 from being concentrated by load from a user due to three-link truss structure of which three hinges 151a, 141a, 138a are formed as rotatable.

Also, by supporting both sides of the track part 110 with two extendable rods, an inclination of the track part 110 in the width direction can be prevented thereby preventing the fluctuation or unbalance thereof in the width direction.

Comprised as above mentioned, the operation mechanism of the inclination control device of the treadmill can be easily understandable referring to that of the foregoing actuator in FIG. 3 and FIG. 4. A difference of rotating direction of the actuator motor 131 makes a pair of screw rods 141 be extruded from the housing 141 by the same length so that the inclination of the track part 110 can be precisely controlled. FIG. 12 illustrates the situation when the length d of extendable rod 140 gets shortest, and thus, the downward inclination of the track part 110 is realized within the range between −10° and 0°

Referring to FIG. 12, in case that the load Fp due to a user's exercise thereon is applied on the front part B of track part 110 as indicated in FIG. 12, the reaction force Fa on the extendable rod 140 and the reaction force Fs on the support member 151 can be calculated as following equations 2 and 3. Fs=Fp×(L2/L1)  EQUATION 2 Fa=Fp×(L4/L3)  EQUATION 3

Therefore, different from the reaction force for the inclination control device of a conventional treadmill (see equation 1), the reaction force Fa on the extendable rod 140 in the axial direction thereof is came to be reduced rather than be increased. Furthermore, any moment is not applied on the extendable rod, since both ends of the extendable rod 140 are formed as the rotatable hinges 138a, 141a. In view that a member came to be broken due to the repeated bending fatigue loads, the actuator 130 can have almost permanent life span because any moment is not applied on the extendable rod 140. As the moment and the reaction force Fa of the extendable rod 140 are minimized, it is possible to design the extendable rod to have a minimized diameter, thereby also realizing the smaller capacity of the actuator motor as well as the reduced weight of the extendable rod 140 (i.e., the housing 141 and the screw rod 142) Accordingly, energy consumption required to drive and to manufacture the actuator 130 can be also reduced.

In addition, by letting the second hinge 141a far apart from the track part 110, as the reaction force on the extendable rod 140 in the axial direction thereof can surprisingly be reduced, when the length of the support member 151 is assumed to be L5, it is more desirable that the length of L3 is longer than 0.5*L5.

As above explained, The present invention provides with an actuator for inclination controlling of treadmill, which comprises: a motor, a pinion rotating with power of the motor, a belt for transmitting power from the motor, a pair of driving pulleys rotatably engaged with the belt, a pair of the screw rod combined with the driving pulley on its one end, a female screw engaging a screw thread of the screw rod, a housing attached to the screw rod by the female screw so that it facilitates inclination control of a track of the treadmill.

In order to maintain the track part stable during a user's exercise on the track part, a pair of the extendable rod including the screw rod and the housing can be contracted or extended by the same length so that the treadmill can be easily and precisely controlled.

In addition, as the present invention provides with an inclination control device of treadmill using the actuator supporting both sides of track part with a pair of the extendable rods, a user can run or walk on the track part 110 without an inclination in the width direction which causes a user feel to unstable and unsafe.

The present invention also can save manufacturing cost and enhance durability surprisingly because the load can be effectively diverged and the moment on the extendable rod is removed by constructing one or a pair of three-linked truss structure of which hinges are all rotatable relative to the near members. Also, the actuator according to the present invention can save power consumption for driving and manufacturing cost.

As the present invention may be embodied in several forms without departing from the spirit or essential characteristics thereof, it should also be understood that the above-described embodiments are not limited by any of the details the foregoing description, unless otherwise specified, but rather should be construed broadly within its spirit and scope as defined in the appended claims, and therefore all changes and modifications that fall within the metes and bounds of the claims, or equivalence of such metes and bounds are therefore intended to be embraced by the appended claims.

On the other hand, although the actuator 130 using belt 137 for transmitting the driving toque is described above as one embodiment of the present invention, any actuator capable of simultaneously controlling a pair of the extendable rod 140 is within the scope of the present invention. Also, the inclination control device having a pair of the extendable rod 140 for achieving three hinges 138a, 141a, 151 for three-linked truss structure is described above as one embodiment of the present invention, an inclination control device only having one extendable rod 140 is also within the scope of the present invention.

Claims

1. An actuator for controlling the inclination of the track part of a treadmill comprising: a motor; a pinion rotatably driven by the motor; a belt formed to transmit the driving force from the pinion; a pair of driving pulleys engaging with the belt so as to receive the driving force from the pinion; a pair of screw rod combined with each of the driving pulley for rotating together with each of the driving pulley; and a pair of housings having female thread for engaging with each of the screw rod; wherein a pair of screw rods are simultaneously extruded from or simultaneously inserted into each of the housing by the same length.

2. The actuator for controlling the inclination of the track part of a treadmill as claimed in claim 1 further comprising: at least one idler pulley engaging with the belt; wherein the belt is engaged with the pinion, the idler pulley, and the driving pulleys for transmitting the driving force from the pinion to the driving pulleys.

3. The actuator for controlling the inclination of the track part of a treadmill as claimed in claim 1, wherein the pinion, the idler pulley, and the driving pulleys has at least one groove on their sides so as to engage with the protuberances periodically formed on the belt.

4. The actuator for controlling the inclination of the track part of a treadmill as claimed in claim 2 further comprising: a bracket for rotatably fixing the pinion, the idler pulley and the driving pulleys; and bracket hinges formed at the both sides of the bracket; housing hinges formed at each of the housings.

5. An inclination control device for a treadmill having at least one track part comprising: at least one support member pivotally connected with at least one first hinge at the track part for extending from the track part to the ground; and at least one extendable rod pivotally connected with at least one second hinge which moves together with the support member, and pivotally connected with at least one third hinge of the track part which is located apart from the first hinge at the track part; wherein, the inclination of the track part is controlled by the extension or the contraction of the extendable rod.

6. The inclination control device for a treadmill as claimed in claim 5, wherein the support members are formed as a pair for pivotally being connected with a pair of the first hinges at the track part, and the extendable rods are formed as a pair for pivotally being connected with a pair of the third hinges at the track part.

7. The inclination control device for a treadmill as claimed in claim 6, wherein a pair of the support members include a traverse member which connects the support members each other, and the second hinges are formed as a pair at the support members or at the traverse member for pivotally being connected with a pair of the extendable rods.

8. The inclination control device for a treadmill as claimed in claim 7, wherein a pair of the extendable rods include a pair of housings having a housing hinge respectively for being pivotally connected with each of the second hinge, and having female thread; and a pair of screw rods engaging respectively with the female thread of each of the housing so as to be extruded from or inserted into each of the housing by relative rotation therebetween; and, further comprising: a pair of driving pulleys combined with each of the screw rod for rotating together with the screw rod; a belt engaging with the driving pulleys; a pinion engaging with the belt for transmitting a driving force via the belt to the driving pulleys; a motor for making the pinion rotate; and a bracket for rotatably fixing the pinion, and the driving pulleys, and having a pair of bracket hinges on its both sides to be pivotally combined with each of the third hinges; wherein one of the first hinges, one of the second hinges, and one of the third hinges form hinges of three-link structure.

9. The inclination control device for a treadmill as claimed in claim 8, wherein the screw rods integrally rotate with each of the driving pulley respectively.

10. The inclination control device for a treadmill as claimed in claim 8, further comprising: at least one idler pulley rotatably fixed to the bracket for engaging with the belt; wherein the belt is engaged with the pinion, the idler pulley, and the driving pulleys for transmitting the driving force from the pinion to the driving pulleys.

11. The inclination control device for a treadmill as claimed in claim 10, wherein the pinion, the idler pulley, and the driving pulleys have at least one groove on their sides so as to engage with the protuberances periodically formed on one side of the belt.

12. The inclination control device for a treadmill as claimed in claim 8, further comprising a roller formed at the end of each of the support member which is contact with the ground.

13. The inclination control device for a treadmill as claimed in claim 8, wherein the second hinges are formed within the range between 0.1 L to 0.5 L from one end contacted with the ground, when the length of the support member is L.

14. The inclination control device for a treadmill as claimed in claim 8, wherein a pair of the extendable rods include a pair of housings having a housing hinge respectively for pivotally connecting with each of the second hinge, and having female thread; and a pair of screw rods engaging respectively with the female thread of each of the housing so as to be extruded from or inserted into each of the housing by relative rotation therebetween; and, further comprising: a pair of driving gears combined with each of the screw rod for rotating together with the screw rod; at least one pair of intermediate gears engaging with the driving gears; a pinion gear engaging with the intermediate gears for transmitting a driving force via the intermediate gears to the driving gears; a motor for making the pinion gear rotate; and a bracket for rotatably fixing the pinion gear, the intermediate gears and the driving gears, and having bracket hinges on its both sides for being pivotally connected with each of the third hinges; wherein one of the first hinges, one of the second hinges, and one of the third hinges form hinges of three-link structure.

15. An inclination control device for a treadmill having at least one track part, comprising: a pair of support members pivotally connected with a pair of first hinges at the track part for extending from the track part to the ground; a pair of housings having a housing hinge respectively for being pivotally connected with a pair of second hinges at the support members, and having female thread; a pair of screw rod engaging respectively with the female thread of each of the housing so as to be extruded from or inserted into by relative rotation therebetween; a pair of driving pulleys combined with each of the screw rod for rotating together with the screw rod; a belt engaging with the driving pulleys; a pinion engaging with the belt for transmitting a driving force via the belt to the driving pulleys; a motor for letting pinion rotate; and a bracket for rotatably fixing the pinion and the driving pulleys, and having a pair of bracket hinges on its both sides to be pivotally combined with a pair of the third hinges at the track part; wherein the third hinges are apart from the first hinges respectively, and wherein one of the first hinges, one of the second hinges and one of the third hinges form a three-linked structure.

16. The inclination control device for a treadmill as claimed in claim 15, wherein the screw rods are integrally rotate with each of the driving pulley respectively.

17. The inclination control device for a treadmill as claimed in claim 15, further comprising: at least one idler pulley rotatably fixed to the bracket for engaging with the belt; wherein the belt is engaged with the pinion, the idler pulley, and the driving pulleys for transmitting the driving force from the pinion to the driving pulleys.

18. The inclination control device for a treadmill as claimed in claim 17, wherein the pinion, the idler pulley, and the driving pulleys have at least one groove on their sides so as to engage with the protuberances periodically formed on one side of the belt.

19. The inclination control device for a treadmill as claimed in claim 15, further comprising a roller formed at the end of each of the support member which is contact with the ground.

20. The inclination control device for a treadmill as claimed in claim 15, wherein the second hinges are formed within the range between 0.1 L to 0.5 L from one end contacted with the ground, when the length of the support member is L.