Driving system for stair-climbing vehicle

A driving system that can allow a vehicle to go over or ascend obstacles or stairs through a step driving manner is provided. The driving system includes a power transmission unit connected to a main shaft connected to a power generation unit installed on the wheel frame, a plurality of driven units engaged with the power transmission unit and supporting the rotation of wheels by rotational force from the power transmission unit, and a carrier to which the power transmission unit and each of the driven units are operationally fixed and which goes over the obstacles by rotating when the driven units are stopped by the obstacles.

FIELD OF THE INVENTION

The present invention relates to a driving system for a stair-climbing vehicle that can be applied to a variety of vehicles, and more particularly, to a driving system that can allow a vehicle to go over obstacles or ascend or descend stairs when the vehicle encounters the obstacles or stairs, while being driving by rotation of its wheels, and which can be stably driven with low power on an even road.

BACKGROUND OF THE INVENTION

Generally, a variety of vehicles such as passenger cars for drivers or passengers, wheelchairs used for patients or handicapped persons, trucks used for carrying cargos and loads, and special cars such as armored vehicles and specially-equipment vehicles have been developed to enhance convenience and be effectively used for special purposes.

As shown inFIG. 1, a conventional vehicle includes a wheel frame1that can be formed in a variety of designs capable of receiving persons or cargos. An engine is mounted on a predetermined location of the wheel frame to generate power. Driving shafts4are further installed on the wheel frame1to drive wheels3by receiving the power from the engine2. Therefore, when the engine operates, the wheels3connected to the driving shafts4rotate to drive and move the vehicle.

The conventional vehicle is generally configured such that the wheels perform only the rotating drive with respect to axle shafts or driving shafts. Therefore, on an even road or when an obstacle is less than a predetermined height, the vehicle can easily move. However, when the vehicle meets a sand field, a muddy field, a high obstacle, or stairs, the wheels may not have any traction or may not go over the obstacle, and thus the vehicle cannot be driven or move.

SUMMARY OF THE INVENTION

Accordingly, the present invention has been made in an effort to obviate one or more of the problems due to limitations and disadvantages of the related art. It is an object of the present invention to provide a driving system for a stair-climbing vehicle, capable of allowing a vehicle to go over obstacles or ascend or descend stairs when the vehicle is driven by rotation of its wheels and encounters the obstacles or stairs and which is stably driven with low power on an even road.

It is another object of the present invention to provide a driving system for a stair-climbing vehicle having a carrier that can be driven when a load greater than a predetermined load is applied to wheels.

It is still another object of the present invention to provide a driving system for a stair-climbing vehicle that can minimize power consumption when a vehicle runs on an even road and prevent going in reverse.

To achieve the objects, the present invention provides a driving system for a stair-climbing vehicle that is installed on a wheel frame to allow a vehicle to go over obstacles and ascend stairs, the driving system including: a power transmission unit connected to a main shaft connected to a power generation unit installed on the wheel frame; a plurality of driven units engaged with the power transmission unit and supporting wheels rotated by rotational force from the power transmission unit; and a carrier to which the power transmission unit and each of the driven units are operationally fixed and which goes over the obstacles by rotating when the driven units stop due to the obstacles.

According to another feature of the present invention, the driving system for a stair-climbing vehicle further includes a wheel shift unit that, when the wheel body having a plurality of wheels connected to the driving system runs on an even road, shifts one of at least two wheels contacting the road away from the road. The wheel shift unit includes a shift plate on a center of which the main shaft of the driving unit is rotatably fixed; a plurality of shift gears provided on end portions of shafts of the wheels extending toward the shift plate; and a support gear, which is provided on a connection shaft rotatably provided on a portion of the shift plate, surface or line-contacts the shift gear selectively, contacts the shift gear to be capable of shifting.

DETAILED DESCRIPTION OF THE INVENTION

Reference will now be made in detail to preferred embodiments of the present invention, examples of which are illustrated in the accompanying drawings. For clarity, a half section of the driving unit is shown in detail. In addition, terms related to direction hereinafter denote viewing from the front of the drawings, and the scope of the present invention is not limited thereto.

Referring first toFIGS. 2 to 5C, a driving system according to an embodiment of the present invention is installed on a wheel frame V of a vehicle such as a passenger car, a commercial car, a carrying unit, and a wheelchair. The driving system is connected to a main shaft S such as an axle shaft provided on a power generation unit M such as a combustion engine or an electric motor installed on the wheel frame V to receive power such as rotational force. In this embodiment, a driving portion related to a first wheel W1among wheels for moving the wheel frame V will be described in detail. It will be obvious that the driving portion will be identically applied to second, third or/and fourth wheels W2, W3, or/and W4.

The main shaft S includes a power transmission unit10for transmitting the rotation power of the main shaft S. The power transmission unit10includes a sun gear12fixed on the main shaft S, a plurality of planet gears14engaged with an outer circumference of the sun gear12, and a ring gear16engaged with outer circumferences of the planet gears14and rotating in a direction in which the planet gears14rotate. Here, each of the planet gears14is rotated about its axis by the rotation of the sun gear12or is rotated around the sun gear by a load. The ring gear16is provided with teeth formed on inner and outer circumferences. A cover16ais connected to the ring gear16to protect the ring gear16from external impacts and to allow the ring gear16to effectively perform driving. The cover16ais connected to a body of the ring gear16by a rod16b.

That is, a driven unit20is installed on the power transmission unit10. The driven unit20may be formed in a gear train having a plurality of gears.

That is, the driven unit20includes a lead gear22engaged with gear teeth formed on the outer circumference of the ring gear16, a connection gear24engaged with the lead gear22, and a driving gear26engaged with the connection gear24. A shaft51of the wheel W1is fixed on the driving gear26to rotate the wheel W1.

The power transmission unit10and the driven unit20may be shielded by a carrier30.

The sun gear12and planet gears14of the power transmission unit10and the lead gear22, connection gear24, and driving gear26of the driven unit20are fixed on the carrier30by their respective shafts S,14a,22a,24a,51, S2, and S3and bearings B.

Further, the carrier30may be designed in a variety of shapes in accordance with the number of the wheels and the arrangement of the gears. Alternatively, the carrier30may be designed in a wheel box shape and substantially function as a wheel box.

As described above, the power transmission unit10and the driven unit20that are applied to the first wheel W1can be identically applied to the second, third, or/and fourth wheels W2, W3, or/and W4. Therefore, like constituent elements of the power transmission unit and driven unit that are related or applied to the second wheel W2have respective reference symbols each assigned with “′”, and constituent elements of the power transmission unit and driven unit that are related or applied to the third wheel W3have respective reference symbols each assigned with “″”. Needless to say, like constituent elements perform like functions. Therefore, a detailed description of like constituent elements will be omitted herein for simplicity.

Alternatively, in one embodiment of the present invention, a driving system having three wheels is described. However, as shown inFIGS. 6A and 6B, it will be obvious that a vehicle or wheelchair having two or four wheels may have identical constituent elements having identical functions. As shown inFIG. 6B, when the vehicle has four wheels, the driving system and constituent elements applied to the wheels W1, W2, and W3will be identically applied to the fourth wheel W4.

Meanwhile, as shown inFIGS. 7A to 9B, a vehicle of a second embodiment of the present invention further includes a wheel shift device40that can minimize consumption of driving force by minimizing a contact area with a road when a vehicle such as a wheelchair moves on an even road. That is, when the vehicle drives on an even ground or a gentle slope, the wheel shift device40functions to allow only one of the wheels W1, W2, W3, or/and W4to contact the road and to maintain shifted states of the rest of the wheels.

The wheel shift device40includes a shift plate42. The main shaft S of the driving system is rotatably fixed on a center of the shift plate42. The shift plate42may be formed in a variety of shapes and designed to be smaller than the carrier30.

Meanwhile, a shift gear44,44′,44″ is integrally formed with an end of a shaft51, S2, S3of the wheel W1, W2, W3, which extends toward the shift plate42through the driving gear26,26′,26″. The shift gear44,44′,44″ integrally rotates together with the wheel W1, W2, W3and the driving gear26,26′,26″.

Correspondingly, a support gear46that is selectively coupled to one of the shift gears44,44′ and44″ is provided on a portion of the shift plate42. The support gear46is rotatably fixed on the portion of the shift plate42by a shaft462.

Especially, the shift gears44,44′, and44″ and the support gear46are formed in a rectangular gear so that they can contact each other. That is, the shift gear44,44′,44″ and the support gear46are formed in the rectangular shape having four flat surfaces44a,44′a,44″a,46aand four corners44b,44b′,44b″,46bso that they can surface-contact each other.

Through the structures and coupling of the shift gear44,44′,44″ and the support gear46, when, for example, the wheelchair operates, each flat surface of the shift gear44,44′,44″ and each flat surface of the support gear46surface-contacts each other and then the shift gear44,44′,44″ rotates around the support gear46within a predetermined range while rotating about its axis. Finally, the corner44b,44′b,44″bor flat surface44a.44′a,44″aof the shift gear44,44′,44″ surface-contacts the flat surface46a. In this state, the shift gear44.44′,44″ rotates about its axis.

In addition, according to another feature of the present invention, the driving system further includes a reverse drive preventing unit50so as to move the wheelchair or other vehicle in an advancing direction desired by the user or passenger.

The reverse drive preventing unit50includes sub-planet gears52,52′,52″ provided on ends of shafts14a,14′a,14″aextending from the respective planet gears14,14′,14″. A sub-ring gear54is rotatably engaged with the sub-planet gears52,52′,52″. Gear teeth54aare formed on an outer circumference of the sub-ring gear54and a ratchet that will be described layer is separately engaged with the gear teeth54aof the sub-ring gear54.

Meanwhile, the ratchet56is installed on the shift plate42. The ratchet56is coupled to one of the teeth54aformed on the outer circumference of the sub-ring gear to prevent the sub-ring gear from reversely rotating—i.e., to prevent the sub-ring from rotating in a direction opposite to the advancing direction. In order for the driver or passenger to stably manipulate the ratchet56manually or automatically, the ratchet56is installed together with a manipulation unit such as a handle on a proper portion of the shift plate42or installed on a manipulation base of the vehicle such as the wheelchair to be remotely controlled.

The ratchet56includes a body56athat is fixed on the shift plate42to be pivoted frontward and rearward, a first coupling member56bthat is formed on one side end of the body56aand detachably coupled to one of the teeth54aof the sub-ring gear54, and a second coupling member56cthat is formed on the other side end of the body56aand detachably coupled to one of the teeth54aof the sub-ring gear.

When the vehicle such as the wheelchair moves frontward, the first coupling member56bof the ratchet56pivots in the forward direction A1to contact one of the teeth54aof the sub-ring gear5in an idle state. At this point, when the wheelchair moves normally in the forward direction, the first coupling member56asimply contacts the tooth54aof the sub-ring gear54. When the wheelchair is inadvertently driven in a reverse direction, one of the teeth54aof the sub-ring gear is coupled to the first coupling member56bto prevent the wheelchair from moving in a reverse direction.

On the other hand, when the vehicle such as the wheelchair moves in a rearward direction by the user or passenger, the second coupling member56cof the ratchet56pivots in a rearward direction A2to contact one of the teeth54aof the sub-ring gear54in an idle state. At this point, when the wheelchair moves normally in the rearward direction, the second coupling member56csimply contacts the tooth54aof the sub-ring gear54. When the wheelchair is inadvertently driven in the forward direction, one of the teeth54aof the sub-ring gear is coupled to the second coupling member56cto prevent the wheelchair from moving in the forward direction.

The following will describe an operation and operational mode of the driving system with reference to the accompanying drawings.

First, when the vehicle in which the driving system is installed runs on an even road or goes over a low obstacle and the power generation unit M such as a motor operates, the sun gear12of the power transmission unit10mounted on the main shaft S rotates counterclockwise and the planet gears14,14′,14″ engaged with the sun gear12rotates about their axes clockwise. In addition, the ring gear16rotates clockwise.

When the ring gear16rotates, the lead gears22,22′,22″ of the driving unit20,20′,20″ engaged with the ring gear16rotate counterclockwise and, at the same time, the driving gear26,26′,26″ rotates counterclockwise.

Accordingly, the first and third wheels W1and W3connected to the respective driving gears26and26″ of the driven units20and20″ advances in an arrow direction A3on the road (seeFIG. 5A). Since the advancing condition of the vehicle is that an idle load of the carrier30is greater than the rotational force of the planet gears about their axes, the planet gears can be limited within a range where they can rotate about their axes.

Meanwhile, when the vehicle moves as described above and meets a high obstacle or stairs, the vehicle can go over the obstacle as the first wheel W1used as a supporting point and the second, third, and first wheels W2, W3, and W1go over the obstacle in this order. When this operation is repeated, the vehicle ascends the stairs ST (seeFIG. 5B).

That is, when the first wheel W1is stuck on the obstacle or stairs ST, the driving gear26of the driven unit20stops and thus the connection gear24and the lead gear22that are sequentially connected to the driving gear26stop simultaneously. At this point, the ring gear16momentarily stops.

Even when the ring gear16stops, the power generation unit M keeps operating to transmit torque to the power transmission unit10through the driving shaft S and thus the sun gear12keeps rotating. At this point, since the load applied to the ring gear16is greater than the force for rotating the planet gears14,14′,14″ about their axes, the planet gears14,14′,14″ rotate around the inner circumference of the ring gear16. As a result, the carrier30connected to the planet gears rotates counterclockwise about the shaft of the driving gear26.

When the carrier keeps rotating as described above, the second wheel W2is disposed in front of the first wheel W1and the third wheel W3is disposed above the first and second wheels W1and W2. Therefore, the vehicle returns to the initial driving state to advance in an arrow direction A5(seeFIG. 5C).

Needless to say, when the obstacle is not high and the vehicle has three wheels, the carrier30rotates 120° (⅓ turn) by one time or two times to go over the obstacle. When the vehicle meets the stairs, the above described rotational movement of the carrier30is continuously repeated so that the vehicle ascends the stairs.

Meanwhile, as shown inFIGS. 7A through 9B, when the wheel shift device40is further mounted on the driving system, the driving system can be driven with less power. That is, as shown inFIG. 9A, when the vehicle such as the wheelchair runs on an even road, as shown inFIG. 9B, a rear wheel (i.e., the third wheel W3is lifted or shifted using the second wheel W2as a supporting point so that only one front wheel (i.e., the first wheel W1) can contact the road.

In more detail, when the vehicle moves on the even road in a state where the first and third wheels W1and W3are disposed in front and rear and contact the road E, as shown inFIG. 9A, the shift gear44′ of the wheel shift device40provided on an end portion of the shaft S2of the second wheel W2rotates about its axis and rotate around the support gear46within a predetermined range in a state where the flat surface46asurface-contacts the supporting gear46of the wheel shift device40in an initial state. Therefore, the wheel shift device40is shifted upward by a predetermined height and thus, the shaft S2and the wheel W2that are connected to the shift gear44′ are lifted or shifted by a predetermined height. In addition, the third wheel W3connected to the shaft S3and the carrier30are also shifted. At this point, the corners44′bor flat surface44′aof the shift gear44′ of the wheel shift device40, which is associated with the second wheel W2, surface or line-contacts the flat surface46aor corner46bof the supporting gear46and thus, the shift gear44′ continues rotating about its axis.

Therefore, as shown inFIG. 9B, the third wheel W3is shifted away from the road E by the shifting operation of the second wheel W2, and only the first wheel W1maintains the contact state with the road. As a result, the vehicle wheelchair or other vehicle moves on the even road smoothly and economically.

In this embodiment, a case where the second wheel W2is associated with the wheel shift device40and lifts the third wheel W3from the road is described. However, it can be understood by a person of ordinary skill in the art that the first and third wheels W1and W3can be identically associated with the wheel shift device40. That is, when the first wheel W1is associated with the wheel shift device40, the second wheel W2is shifted away from the ground. When the third wheel W3is associated with the wheel shift device40, the first wheel W1is shifted away from the ground.

Meanwhile, when the reverse drive preventing unit50is provided to the driving system of the present invention, the vehicle can move in a direction the user wants without being reversely driven or pushed backward.

In more detail, when the user intends to move the wheelchair frontward on a sloped road or hill and thus pivots the ratchet56in the arrow direction A1, the first coupling member56bcontacts the tooth54aof the sub-ring gear54in an idle state. That is, when the wheelchair moves frontward, the first coupling member56bsimply contacts the tooth54aof the sub-ring gear54so that the wheelchair can move frontward normally. However, when the wheelchair is inadvertently driven in a reverse direction to stop, the first coupling member56bprovided on the one side end of the body56aof the ratchet56is coupled to one of the teeth54aof the sub-ring gear54to prevent the sub-ring gear54from rotating, thereby preventing the wheelchair from being driven in the reverse direction.

On the other hand, when the user intends to move the wheelchair rearward and thus pivots the ratchet56in the arrow direction A2, the second coupling member56ccontacts the tooth54aof the sub-ring gear54in an idle state. That is, when the wheelchair moves rearward, the second coupling member56csimply contacts the tooth54aof the sub-ring gear54so that the wheelchair can move normally rearward. However, when the wheelchair is inadvertently driven in the forward direction to stop, the second coupling member56cof the ratchet56is coupled to one of the teeth54aof the sub-ring gear54to prevent the sub-ring gear54from rotating, thereby preventing the wheelchair from being driven in the reverse direction.

Needless to say, when the user or passenger intends to move the wheelchair frontward or rearward, the ratchet56is manipulated such that the coupling member56b,566cdoes not contact or smoothly contact the tooth54aof the sub-ring gear54so that the sub-ring gear54can smoothly rotate in a direction the user wants, thereby enabling the wheelchair to move forward and rearward.

Although only a case where the vehicle moves frontward is described in the above embodiment, the vehicle can move rearward and perform the stepping operating by reversely operating the power generation unit or reversely rotating the main shaft using a differential unit.

In addition, when the driving system is installed to be associated with the driving shaft of the front wheels, the front wheels can be used as wheels associated with a steering wheel. When the driving system is installed to be associated with the driving shaft of the rear wheels, fuel consumption can be reduced and faster speeds can be realized. Needless to say, the driving system may be installed to be associated with both of the driving shafts of the front and rear wheels.

As described above, according to the driving system of the present invention, the driving system can allows the wheelchair or other vehicle to go over obstacles by rotating the carrier using a driving gear connected to one of the wheels as a supporting shaft and allowing the following wheels to go over the front wheel and can allow the vehicle to ascend the stairs by continuously performing the above rotation of the carrier.

Further, when the wheelchair or other vehicle having three or more wheels runs on the even road, the driving system can reduce power consumption and maintain a smooth running state by shifting a rear one of two wheels contacting the road away from the road.

In addition, since the driving system has the reverse drive preventing unit that can prevent the vehicle from driving in a direction the user does not want, driving stability can be enhanced.