Transmission and transport device including train using the transmission

A transmission and a motor or non-motor type transport device including a cross-coupling power train using the transmission, such as chainless bicycle or wagon with two or four wheels are disclosed. The transmission includes a coarse adjustment gearshift of internal gear type and a fine adjustment gearshift of differential gear type which are mounted on a main shaft to change the speed and are selectively connected to each other by a shift lever to provide low-speed rotation and high-speed rotation.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a transmission and a motor or non-motor type transport device including a cross-coupling power train using the transmission, such as chainless bicycle or wagon with two or four wheels.

2. Background of the Related Art

A transport device such as bicycle or wagon is self-propelled, and is classified into a non-motor type which transmits a pedal force to a rear wheel(s) via a pedal, a crank arm and a chain, and a motor type which transmits a driving force from an engine to a rear wheel(s) via a chain.

Such a transport device is necessarily provided with a power train for transmitting a pedal force or a driving force of an engine to a rear wheel(s) in order for its operation.

The power train of the transport device includes a transmission for increasing the pedal force or the driving force of the engine and increasing or reducing speed to change a gear ratio in accordance with road conditions or operation. The transmission employs sprockets of various sizes which are arranged in order, and chains for connecting the sprockets.

The construction of the transmission employing the sprockets and the chains is complicated and is limited to a shift range. Also, since the driving force is not smoothly transmitted by the chains connecting the sprockets which are arranged in order, the shift change is not smoothly and quickly performed.

More specifically, in case where the shift is performed from a high stage to a low stage or vice versa while skipping over an adjacent stage, the shift operation should pass through sprockets arranged between both gearshifts, as described above. Also, since a traveling distance should be required for the sequential shift process, it is not easy to instantaneously change the gearshift at low or high speed, for example, on a sloping road.

Although the traveling to operate the transmission using the multi-stage sprocket and chain is not out of the question on a flat road, the shift is not smoothly performed on an uphill road or downhill road, thereby inefficiently transmitting the driving power and thus causing unnecessary energy loss. Also, the transport device cannot travel on a steep or irregular slope, which deteriorates the performance of the transport device.

In order to improve the construction of a power transmission system and reducing the power loss, power trains for a chainless transport device have been developed. One example of the power trains is a bicycle using a cross-coupling power train.

More specifically, a cross-coupling power train including a bevel gear or a crown type gear and a roller type gear is installed between a main shaft of a crank arm and a rear wheel to transmit the driving force from the crank arm to the rear wheel.

Also, the cross-coupling power train includes a transmission operated by the shift lever which is provided on a handle bar, so as to drive the bicycle by properly shifting the transmission in accordance with conditions of travel roads, such as a flat road or slope road. In this instance, the transmission of the power train includes a cross-coupling power transmitting system, planetary or sun gears, or large and small spur gears which are arranged in a multi-stage and are sequentially connected to each other to change the speed.

However, the transmission has a narrow shift range, in which a shift stage is gradually moved at a constant ratio within a certain shift width. Also, under the specific traveling conditions requiring for spontaneous low-speed shift on a slope road, the shift operation of the transmission is not easily performed due to the required traveling distance or strong load.

Also, the power transmission is not effectively performed since the proper shift is not carried out on the slope road, so that the bicycle does not properly travel. In case of a mountain area having an irregular steep slope which requires a large shift ratio, a driver stops off the bicycle since the speed does not changed by strong torque and low rotation at a low-speed stage.

In the transmission applied to the power train for transport devices such as bicycle or wagon, the torque is maximized at a constant speed, while strong torque and low rotation are required at initial drive or on a slope road. As the speed is increased, the transmission increases the rotation rather than the torque. The low- or high-speed shift operation should be quickly carried out in accordance with the traveling conditions, in particular, on an uphill or downhill road.

In case of mountain bikes, the low-speed shift of low rotation and strong torque is required on a mountain area including irregular and steep slopes, but the shift is not properly performed to make the continuous travel impossible.

SUMMARY OF THE INVENTION

Accordingly, the present invention is directed to a mounting structure of an advertising display frame for a shopping cart that substantially obviates one or more problems due to limitations and disadvantages of the related art.

One object of the present invention is to provide a transmission which can effectively transmit a driving force by selectively performing speed change while maintaining a wide range of low- or high-speed shift ratio.

In order to accomplish these objects, there is provided a transmission including a coarse adjustment gearshift of internal gear type and a fine adjustment gearshift of differential gear type which are mounted on a main shaft to change the speed and are selectively connected to each other by a shift lever to provide low-speed rotation and high-speed rotation. The transmission solves the problem contained in the prior art, in which the strong torque and low rotation are not obtained when sudden load requiring a large shift difference occurs, since the shift is gradually performed in a narrow shift range.

According to another aspect of the present invention, there is provided a 2-wheel or 4-wheel chainless transport device such as a bicycle or wagon including the above transmission which can effectively transmit the driving force at a wide shift range. The transmission can perform the selective shift at each low or high stage in accordance with traveling conditions such as a flat road or slope road. In particular, the transport device can continuously travel even on mountain area including irregular steep slopes, without stopping over the transport device, since it can obtain the strong torque and low rotation, as well as freely changing the sped on the slope road.

With the above construction, since the coarse adjustment gearshift and the fine adjustment gearshift are selectively connected to each other, the transmission of the present invention can obtain a wide shift range at low and high sped rotation.

The transport device according to the present invention can quickly change the speed, without requiring a traveling distance for the shift on an irregular slope road in a mountain area, and stopping over the transport device.

Also, the present invention can effectively transmit a driving force while maintaining a wide shift range of low or high speed, and can reduce energy loss.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

A preferred embodiment according to the present invention will now be explained with reference to the accompanying drawings.

The present invention may be applied to power transmitting systems which transmit a driving force to a load to drive a motor type or non-motor type transport device.

FIGS. 1 to 3show a transmission according to the present invention which is installed in a proper position in a power transmitting system and is shifted by a shift lever to effectively transmit a driving force to a load. The transmission includes a two-segmented housing110enclosing components to be described hereinafter.

The housing110includes a main shaft120for receiving the driving force in a horizontal direction in an inside of the housing. A fine adjustment gearshift130for fine shift, a coarse adjustment gearshift140for low and high speed shift, and outputs150are arranged on the main shaft120. Both ends of the housing110are enclosed by covers110aand110b.

The respective components built in the housing110will now be described in detail.

First, the fine adjustment gearshift130is mounted on the main shaft120, as shown inFIGS. 2a,2band4a, and is moved in a left or right direction along a guide path111provided on an inner wall of the housing110by manipulating a shift lever. The fine adjustment gearshift130is used as a differential gear, in which the driving force is transmitted to any one of two input paths and is outputted to a fine adjustment stage.

The fine adjustment gearshift130includes a casing131freely rotated around the main shaft120, the casing131consisting of a pair of half bodies131aand131beach having a first output13aat its distal end.

The casing131includes a stationary side gear132idling on the main shaft120and having a coupling end132aapplied with a operation force from the shift lever, a movable side gear133having an input133awhich is selectively connected to or disconnected from the main shaft120through spline shaft coupling and a second output133b, and at least one pinion134meshed with the stationary or movable side gear132or133and having an input134awhich is selectively connected to or disconnected from the main shaft120through spline shaft coupling, the pinion being coupled to the casing131to revolve or rotate.

The coarse adjustment gearshift140is movable along the guide path111formed on an inner wall of the housing110by the operation of the shift lever transmitted through a coupling end143which is extended from one end of the main shaft120, as shown inFIGS. 2a,2band4b. The coarse adjustment gearshift140is used as an internal gear, in which the coarse adjustment gearshift is selectively connected to the two outputs130aand133bof the fine adjustment gearshift130to receive the driving force from any one of two paths and thus connect any one of the outputs130aand133bwith the low- or high-speed coarse adjustment stage.

The coarse adjustment gearshift140includes a roller type pinion141installed on an eccentric shaft and having a sleeve type input140areceiving the driving force by selective engagement with or disengagement from the outputs130aand133bof the fine adjustment gearshift130, an internal gear142meshed with the pinion141, and first and second outputs140band140ceach provided on the end of the pinion141and the end of the internal gear142and outputting the driving force to the output part150through the spline coupling with the output part150by the operation of the shift lever.

In the mesh relationship between the pinion141and the internal gear142of the coarse adjustment gearshift140to obtain proper transmission, if the pinion141has 7 teeth, as shown inFIG. 2c, the internal gear142has 9 teeth.

The output part150is installed on the main shaft120, and is connected to the outputs of the coarse adjustment gearshift to receive the driving force by the cross-coupling power transmitting manner.

The output part150has a roller type gear151with first and second inputs150aand150bwhich are selectively connected to the respective first and second outputs140band140cof the coarse adjustment gearshift140by the spline coupling to receive the driving force, and a crown type gear152cross-coupled to the roller type gear151.

The crown type gear152has an interlock rod220for transmitting the power to the load.

With the construction of the transmission according to the present invention, the shift process is performed from the respective low- and high-speed stages of the coarse adjustment to the 1-, 2-, or 3-stage of the fine adjustment.

The shift process of the transmission according to the present invention will now be described with reference toFIGS. 5ato5e.

FIGS. 5aand5bshow the low-speed shift step, in whichFIG. 5ashows a low-speed 1 stage. The fine adjustment gearshift130is moved in a left direction by the operation of the shift lever, while the coarse adjustment gearshift140is moved in a right direction.

Referring to the power transmitting path indicated by the arrow W in the drawings, the driving force is transmitted to the movable side gear133from the main shaft120through the input133aof the movable side gear133of the fine transmission gearshift130to rotate the movable side gear133, and the pinion134meshed with the movable side gear133is turned to rotate the casing131.

The driving force transmitted to the casing131is outputted to the first output130aof the fine adjustment gearshift130, and then the driving force is transmitted to the pinion141and the internal gear142through the input140aof the coarse adjustment gearshift140. Then, the driving force is transmitted to the first input150aof the output part150through the second output part140c.

The driving force transmitted to the output part150is outputted to the interlock rod220through the roller type gear151and the crown type gear152to reduce the speed at a shift ratio of 0.11. Herein, the gear ratio means the rotation number of the output part150per one rotation of the main shaft120.

FIG. 5bshows a low-speed 2 stage, in which the fine adjustment gearshift130is moved to a neutral position by the operation of the shift lever, and the coarse adjustment gearshift140is positioned at a right side, like the low-speed 1 stage. In this instance, the driving force is transmitted from the main shaft120to the input134aprovided on the pinion134of the fine adjustment gearshift130, as the power transmitting path indicated by the arrow W in the drawings, so that the pinion134is rotated by the driving force directly transmitted through a path different from that of the low-speed 1 stage to rotate the casing131.

The driving force transmitted to the casing131is outputted to the first output130aof the fine adjustment gearshift130, and then is transmitted to the first input150aof the output part150through the input140aof the coarse adjustment gearshift140, the pinion141and the internal gear142, and the second output140cin order.

And, the driving force transmitted to the output part150is outputted to the interlock rod220through the roller type gear151and the crown type gear152to reduce the speed at a shift ratio of 0.22.

FIGS. 5cto5eshow the high-speed shift step, in whichFIG. 5cshows a high-speed 1 stage. The fine adjustment gearshift130is moved in a left direction by the operation of the shift lever, while the coarse adjustment gearshift140is moved in a left direction.

Referring to the power transmitting path indicated by the arrow W in the drawings, the driving force is transmitted to the movable side gear133from the main shaft120through the input133aof the movable side gear133of the fine transmission gearshift130to rotate the movable side gear133, and the pinion134meshed with the movable side gear133is turned to rotate the casing131.

The driving force transmitted to the casing131is outputted to the first output130aof the fine adjustment gearshift130, and then the driving force is transmitted to the second input150bof the output part150through the input140aof the coarse adjustment gearshift140, the pinion141and the first output140b.

The driving force transmitted to the output part150is outputted to the interlock rod220through the roller type gear151and the crown type gear152to increase the speed at a shift ratio of 0.5.

FIG. 5dshows a high-speed 2 stage, in which the fine adjustment gearshift130is moved to a neutral position by the operation of the shift lever, and the coarse adjustment gearshift140is positioned at a left side, like the high-speed 1 stage.

In this instance, the driving force is transmitted from the main shaft120to the input134aprovided on the pinion134of the fine adjustment gearshift130, as the power transmitting path indicated by the arrow W in the drawings, so that the pinion134is rotated by the driving force directly transmitted through a path different from that of the high-speed 1 stage to rotate the casing131.

The driving force transmitted to the casing131is outputted to the second output130bof the fine adjustment gearshift130, and then is transmitted to the second input150bof the output part150through the input140aof the coarse adjustment gearshift140, the pinion141, and the first output140bin order.

And, the driving force transmitted to the output part150is outputted to the interlock rod220through the roller type gear151and the crown type gear152to increase the speed at a shift ratio of 1.

FIG. 5eshows a high-speed 3 stage, in which the fine adjustment gearshift130is moved to a right position by the operation of the shift lever, and the coarse adjustment gearshift140is positioned at the left side, like the high-speed 1 stage.

In this instance, the driving force is transmitted from the main shaft120to the input134aprovided on the pinion134of the fine adjustment gearshift130, as the power transmitting path indicated by the arrow W in the drawings, so that the driving force is directly transmitted to the pinion134through the same path as that of the high-speed 2 stage.

The pinion134is rotated by the transmitted driving force. In this instance, the pinion134rolls along the stationary side gear132, and the rotation force of the pinion134is transmitted to the movable side gear133to output the driving force through the second output133b.

The driving force outputted to the second output133bof the movable side gear133is transmitted to the second input150bof the output part150through the input140aof the coarse adjustment gearshift140, the pinion141, and the first output140bin order.

And, the driving force transmitted to the output part150is outputted to the interlock rod220through the roller type gear151and the crown type gear152to increase the speed at a shift ratio of 2.

The transmission of the present invention can easily perform the shift of wide range comprising the low-speed rotation and the high-speed rotation, since the coarse adjustment gearshift130and the fine adjustment gearshift140are selected by the operation of the shift lever.

FIGS. 6 and 7show another embodiment of the present invention, in which a chainless bicycle of non-motor type including a power train having the transmission is shown as one example of two-wheeled or four-wheeled transport device.

The chainless bicycle includes a crank arm16having a handle bar12and a pedal14, the handle bar12having a shift lever10, a frame18rotatably supporting the crank arm16by using a main shaft120, and front and rear wheels20and22installed at front and rear portions of the frame18, in which a driving force generated from the crank arm16is transmitted to the rear wheel22in a cross-coupling transmitting manner via a driving unit100, a power train unit200and a driven unit300.

More specifically, the driving unit100includes a fine adjustment gearshift130, an output part150which are installed on the main shaft120of the crank arm16, as described above the transmission. The driving force of the crank arm16is effectively shifted in accordance with the driving conditions by operation of the shift lever, while maintaining the shift range of high and low speed.

The power train unit200is cross-coupled to the output part150of the driving unit100to transmit the driving force generated from the output part150to the driven unit300of the rear wheel22which corresponds to a load. The power train unit200includes a pipe-shaped case210connected to both ends of the respective driving and driven units100and300, and an interlock rod220connected to the driven unit300and the output unit150of the driving unit100at both ends thereof.

The driven unit300installed on the rear wheel22includes a roller type gear310coupled to the shaft22aof the rear wheel22, a crown type gear320cross-coupled to the roller type gear310and receiving the driving force of the crank arm16through the power train unit200, and a housing330enclosing the gears310and320.

The driven gear300also includes a latch structure340for transmitting the driving force of the crank arm from the driving unit100through the power train unit200in one way, as shown inFIG. 8.

The latch structure340is interposed between the hub23of the rear wheel22and the roller type gear310. The latch structure340includes a receiving groove340aformed on any one of a hub23and a roller type gear310, a claw340bmoving around the receiving groove, and a claw wheel340cformed on an inner periphery of the roller type gear310. In case where the pedal is driven in a forward direction, the power is transmitted to the rear wheel22, while in case where the pedal is driven in a reverse direction, the power is not transmitted.