Patent Application
20070000405
The present invention relates to a system of rail vehicles such as overhead traveling vehicles, and a method of using the system. In particular, the present invention relates to a technique for allowing the rail vehicle to travel straight through a branch section or a merge section smoothly at high speed.
The rail vehicle system includes a travel rail having branch sections and merge sections. The branch section and the merge section have the same structure except that the travel direction in the branch section is opposite to the travel direction in the merge section. The branch section includes a straight lane and a branch lane with a curve. The merge section includes a straight lane and a merge lane with a curve. In the branch section or the merge section, a gap as a discontinuous portion of a travel surface is present. In order to reduce the impact when the rail vehicle passes the gap, it has been customary to provide auxiliary wheels inside the left and right travel wheels. In the specification, the shift from the state where the travel wheel rides on the ground to the state where the auxiliary wheel rides on the ground is referred to as the “wheel shift”.
In the case where the rail vehicle is on the straight lane of the branch section or the merge section, normally, the rail vehicle travels at high speed in comparison with the case where the rail vehicle is on the branch lane or the merge lane. If the wheel shift operation is performed when the rail vehicle travels at high speed, at the moment the auxiliary wheels land on the travel surface, an impact is applied to the travel surface. As a result, the travel surface is vibrated to generate vibration of the rail vehicle or noises. For example, the travel surface for landing of the auxiliary wheel has a triangular shape protruding toward the inside of the branch section or the merge section, and the rigidity of the travel surface is not sufficient. Since the auxiliary wheel lands on the front end of the travel surface, the travel surface can be vibrated easily. The vibration at the time of the wheel shift adversely affects the rail vehicle, the transported article, and the travel rail. Therefore, the rail vehicle cannot travel straight through the branch section or the merge section at high speed smoothly. The inventor studied to reduce the vibration which is generated when the rail vehicle travels straight though the straight lane of the branch section or the merge section, and achieved the present invention.
An object of the present invention is to allow a rail vehicle to travel straight through a branch section or a merge section smoothly.
Secondary object of the present invention is to provide specific structure to achieve the above object.
Secondary object of the present invention is to make it possible to control the orientation of the rail vehicle simply by specially fabricating a travel rail without any modification to the rail vehicle.
According to the present invention, a rail vehicle system comprises:
a rail vehicle having left and right travel wheels;
a travel rail having left and right travel surfaces, the left and right travel surfaces being separated from each other to form a space between the left and right travel surfaces for supporting the left and right travel wheels, the travel rail having a discontinuous portion in one of the left and right travel surfaces to form a gap in a branch section or a merge section of the rail; and
orientation control means for controlling orientation of the rail vehicle near the gap by floating the travel wheel on the gap side above the travel surface such that the travel wheel on the side opposite to the gap supports the rail vehicle.
The meaning of “floating the travel wheel on the gap side” includes the case where the travel wheel on the gap side is lowered from the position floated by the orientation control means due to deflection of the travel rail, and the travel rail contacts the travel surface at substantially the zero pressure.
Preferably, the left and right travel wheels comprise left and right normal wheels and left and right auxiliary wheels inside the normal left and right wheels in the left-right direction;
the travel rail includes left and right guides for guiding the rail vehicle traveling through the branch section or the merge section, the left and right guides being provided outside the left and right auxiliary wheels in the left-right direction, at the height where the left and right guides do not contact the travel wheels;
the rail vehicle includes guide rollers guided by the left and right guides; and
the orientation control means lifts the auxiliary wheel upwardly relative to the normal wheel, on the side opposite to the gap.
Preferably, for traveling through the branch section and the merge section, the left and the right travel surfaces are configured such that,
when the rail vehicle travels along a straight lane, both of the travel wheel and the auxiliary wheel on the side opposite to the gap are supported by the travel surface, and after the rail vehicle passes the gap, the auxiliary wheel on the gap side is supported by the travel surface firstly, and then, the normal wheel on the gap side is supported by the travel surface; and
when the rail vehicle travels along a branch lane or a merge lane, the normal wheel on the gap side is supported by the travel surface, and after the rail vehicle passes the space between the left and right travel surfaces, the auxiliary wheel on the side opposite to the gap is supported by the travel surface firstly, and then, the normal wheel on the side opposite to the gap is supported by the travel surface.
In particular, preferably, on the side opposite to the gap, the orientation control means is configured to shift the travel surface on the auxiliary wheel side upwardly relative to the travel surface on the normal wheel side.
Most preferably, on the side opposite to the gap, the travel surface on the auxiliary wheel side is shifted upwardly in comparison with the travel surface on the normal wheel side, and the height of the travel surface on the normal wheel side is substantially the same as the travel surface at positions other than the gap.
Preferably, on the side opposite to the gap, the travel surface on the normal wheel side is shifted downwardly in comparison with the travel surface on the auxiliary wheel side, and the height of the travel surface on the auxiliary wheel side is substantially the same as the height of the travel surface at positions other than the gap.
According to the present invention, in a transportation method, a rail vehicle having left and right travel wheels is used, and a travel rail having left and right travel surfaces is used, the left and right travel surfaces being separated from each other to form a space between the left and right travel surfaces for supporting the left and right travel wheels, the travel rail having a discontinuous portion in one of the left and right travel surfaces to form a gap in a branch section or a merge section of the rail, the method comprising the step of:
controlling orientation of the rail vehicle near the gap by floating the travel wheel on the gap side above the travel surface such that the travel wheel on the side opposite to the gap supports the rail vehicle.
Preferably, the left and right travel wheels comprise left and right normal wheels and left and right auxiliary wheels inside the normal left and right wheels in the left-right direction;
the travel rail includes left and right guides for guiding the rail vehicle traveling through the branch section or the merge section, the left and right guides being provided outside the left and right auxiliary wheels in the left-right direction, at the height where the left and right guides do not contact the travel wheels;
the rail vehicle includes guide rollers guided by the left and right guides; and
in the orientation control step, the auxiliary wheel is lifted upwardly relative to the normal wheel, on the side opposite to the gap.
In particular, preferably, for traveling through the branch section and the merge section, the left and the right travel surfaces are configured such that,
when the rail vehicle travels along a straight lane, both of the travel wheel and the auxiliary wheel on the side opposite to the gap are supported by the travel surface, and after the rail vehicle passes the gap, the auxiliary wheel on the gap side is supported by the travel surface firstly, and then, the normal wheel on the gap side is supported by the travel surface; and
when the rail vehicle travels along a branch lane or a merge lane, the normal wheel on the gap side is supported by the travel surface, and after the rail vehicle passes the space between the left and right travel surfaces, the auxiliary wheel on the side opposite to the gap is supported by the travel surface firstly, and then, the normal wheel on the side opposite to the gap is supported by the travel surface.
In the present invention, when the rail vehicle passes the gap, the travel wheel on the gap side is floated above the travel surface by the orientation control means. Therefore, the travel wheel on the gap side does not contact the travel surface. Even if the travel wheel contacts the travel surface, the contact pressure is small in comparison with the other positions. Therefore, the vibration or the noises at the time the rail vehicle passes the positions before, and after the gap is reduced. Thus, the rail vehicle can smoothly travel straight through the branch section or the merge section. For example, the rail vehicle can travel through the branch section or the merge section at high speed, or the durability of the travel rail and the rail vehicle or the load applied to the transported article is reduced.
In the case where the travel rail has left and right guides outside the left and right auxiliary wheels in the left-right direction for guiding the rail vehicle to travel along the branch lane or the merge lane, the guides function as supports for preventing wobbling in the surface perpendicular to the travel direction of the rail vehicle. Therefore, the moment of the support force applied to the auxiliary wheels and the moment of the gravity force of the rail vehicle are offset. If the auxiliary wheels are lifted upwardly relative to the normal wheels on the side opposite to the gap, the normal wheel and the auxiliary wheel on the gap side can be floated above the travel surface easily.
Simply by specially fabricating the travel rail on the side opposite to the gap such that the travel surface on the auxiliary wheel side is shifted upwardly relative to the travel surface on the normal wheel side, it is possible to float the normal wheels and the auxiliary wheels on the gap side. Further, it is possible to easily manufacture the travel rail having the structure in which the vertical shift of the travel surface starts gently, and ends gently. Thus, the support force can be shifted between the travel wheel on the gap side and the auxiliary wheel on the side opposite to the gap.
Hereinafter, an embodiment in the most preferred form for carrying out the present invention will be described.
FIGS. 1 to 6 show an embodiment using an overhead traveling vehicle as a rail vehicle. In the drawings, a reference numeral 1 denotes a branch section, and the branch section is similar to a merge section. Reference numerals 2 and 3 denote a pair of front and rear traveling vehicles. In the drawings, the front traveling vehicle is denoted by the reference numeral 2, and the rear traveling vehicle is denoted by the reference numeral 3. Normal travel wheels 4, 5 are provided on left and right sides of the traveling vehicles 2, 3. Further, auxiliary wheels 6, 7 are provided inside the travel wheels 4, 5 in the left-right direction. For example, the auxiliary wheels 6, 7 have the diameter same as that of the travel wheels 4, 5. A reference numeral 8 denotes the entire overhead traveling vehicle. Reference numerals 9 denote shafts connecting an overhead traveling vehicle body 50 and the traveling vehicles 2, 3. Reference numeral 10 denotes a joint coupling the front and rear traveling vehicles 2, 3 together. A reference numeral 12 denotes a travel motor, and a reference numeral 13 denotes a travel drive wheel. The travel drive wheel 13 is driven by drive means (not shown) and contacts a ceiling surface of a travel rail 42 for allowing the traveling vehicles 2, 3 to travel along the travel rail 42.
Positions of travel surfaces 14 to 19 of the travel rail 42 are shown by chain lines or the like in
For example, as shown in
In the case of straight traveling in the branch section 1, the guide rollers 24 on the straight lane side are lifted, and the guide rollers 26 on the branch lane side are lowered such that the guide rollers 26 can pass under the bottom of the wide section 36. The guide rollers 20, 24 are guided on both left and right surfaces of the wide section 34 to travel along the straight lane. In the case of branch traveling, the guide rollers 24 are lowered, and the guide rollers 26 are lifted for guiding the guide rollers 22, 26 on both sides of the wide section 36 to travel along the branch lane.
For example, as shown in
In the case where the load from the traveling vehicle 2 is not applied to the auxiliary travel surface 17, the auxiliary travel surface 17 is higher than the auxiliary travel surfaces 18, 19 and the travel surface 14 by, e.g., several millimeters. When the traveling vehicles 2, 3 actually travel on the auxiliary travel surface 17, since the load from the traveling vehicles 2, 3 is applied to the auxiliary travel surface 17, the auxiliary travel surface 17 is deformed, and becomes higher than the travel surface 14 and the auxiliary travel surfaces 18, 19 by 0 mm to 2 mm near the gap. It should be noted that it is difficult to match the height of the travel surface 14 and the height of the auxiliary travel surfaces 18, 19 perfectly. Therefore, it is preferable that the auxiliary travel surface 17 becomes slightly higher than the auxiliary travel surfaces 18, 19 by, e.g., 0.1 mm to 1 mm while the traveling vehicles 2, 3 are traveling.
Further,
In the embodiment and the modified embodiment, the following advantages can be obtained.
(1) When the overhead traveling vehicle passes a position near the gap, the travel wheels 5 and the auxiliary wheels 7 float slightly above the auxiliary travel surfaces 18, 19 or contact these surfaces 18, 19 lightly. Therefore, the impact at the time of shifting from the auxiliary travel surface 18 to the auxiliary travel surface 19 can be avoided.
(2) By the control of the orientation of the traveling vehicle 2 or the like, the balance of the supporting force changes gently between the state where the load is supported mainly by the auxiliary wheel 6 and the state where the travel wheel 5 on the branch lane side contacts the auxiliary travel surfaces 18, 19. Thus, the travel wheel 5 gently leaves the auxiliary travel surface 18, and gently rides on the auxiliary travel surface 19. Accordingly, the overhead traveling vehicle smoothly travels straight through the branch section.
(3) The embodiment of FIGS. 1 to 6 can be carried out simply by providing the deformed section 54 on the auxiliary travel surface 17, and conventional vehicles can be used as the traveling vehicles 2, 3.
(4) Since the impact at the time of wheel shift from the auxiliary travel surface 18 to the auxiliary travel surface 19 is reduced, the vibration or noises generated during the wheel shift are reduced. Therefore, the durability of the travel rail and the durability of the overhead traveling vehicle are improved. Further, the force applied to the transportation article such as a semiconductor wafer is reduced.
(5) In the embodiment of FIGS. 1 to 6, when the overhead traveling vehicle travels straight through the branch section at the speed of 200 m per minute, the maximum acceleration in the vertical direction in the branch section as the level of vibration can be reduced 60% in comparison with the case where the deformed section 54 is not provided.
Although the embodiment has been described in connection with the case where the overhead traveling vehicle travels straight though the branch section 1, the present invention is also applicable to the case where the overhead traveling vehicle travels straight through the merge section. That is, the structure of the branch section 1 with modification where the downstream side and the upstream side of the travel rails 42, 42′ are reversed corresponds to the structure of the merge section. In the case where the overhead traveling vehicle travels through the branch section 1 along the branch lane, or in the case where the overhead traveling vehicle moves into the merge section while traveling along a curve, in consideration of the curve, the traveling speed of the overhead traveling vehicle needs to be low in comparison with the case where the overhead traveling vehicle travels straight, and the impact at the time of wheel shift is small. Therefore, it is sufficient that only the case where the overhead traveling vehicle travel straight through the branch section or the merge section is considered. Further, in the case of the modified embodiment of
In addition to the above, the inventor tried to reduce the impact at the time of wheel shift, by increasing the rigidity of the auxiliary travel surface 19. However, since the auxiliary travel surface 19 protrudes toward the inside of the branch section, it was difficult to increase the rigidity, and reduce the impact at the time of wheel shift. Further, the inventor attempted to change the auxiliary wheels 6, 7 into two front and rear wheels having the smaller diameter, and make the shifting to occur at an earlier timing so that, when the overhead traveling vehicle passes the gap 40, the front auxiliary wheel contacts the auxiliary travel surface 19, before the travel wheel 5 leaves the auxiliary travel surface 18. However, the reduction in the impact was small.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2005-194513 | Jul 2005 | JP | national |
