JPH11245673A - Bus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce a deficiency when an engine is arranged by offseting its position of the center of gravity to the opposite side of the getting on/off port to the center in the width direction of a bus 1, as well as to realize the lower floor of the bus, even though a compressed natural gas is used as the fuel for an engine loaded in the bus. SOLUTION: At the rear end of a bus 1, an engine 5 is arranged to offset its position of the center of gravity to the opposite side of the getting on/off port to the center in the width direction of the bus 1, and cylinders 9 of the compressed natural gas to be the fuel of the engine 5 are provided on a roof 10. In this case, the position of the center of gravity of the whole bodies of the cylinders 9 is offset to the opposite side of the position of the center of gravity of the engine 5, to the center in the width direction of the bus 1.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vehicle using compressed natural gas as a fuel for an onboard engine, and more particularly to a low-floor bus.

[0002]

2. Description of the Related Art In the field of rear engine type route buses, low-floor buses such as no-step buses, which have no steps from the entrance to the floor surface, have been attracting attention in order to improve getting on and off. For low-floor buses, in order to ensure a low passage width near the rear entrance,
The engine may be mounted so that the center of gravity is offset to the opposite side of the entrance / exit with respect to the center in the width direction of the vehicle, that is, to the right. However, if the position of the center of gravity of the engine is offset to the right of the center in the width direction of the vehicle as described above, a large load difference occurs between the left and right rear wheels.
In addition to concerns about uneven wear of the rear tires, the center of gravity of the engine is compared to a bus located almost in the center between the left and right rear wheels. There were problems such as the need to change.

On the other hand, it is conceivable to use natural gas as fuel for the engine as one of the alternatives to purifying the exhaust of the engine and replacing petroleum in the bus.
In this case, the fuel cylinder is suspended under the floor of the vehicle body by suspending the fuel cylinder on the vehicle body frame with brackets or bolts. It is structurally difficult to lower the floor.

[0004]

SUMMARY OF THE INVENTION The present invention is directed to the use of compressed natural gas as a fuel for an engine mounted on a bus.
At the same time as making it easier to lower the floor of the bus,
It is an object of the present invention to reduce a problem when the engine is disposed with the center of gravity offset from the center of the bus in the width direction to the side opposite to the entrance.

[0005]

For this reason, the bus according to the present invention is equipped with an engine so that the center of gravity is offset to the opposite side of the entrance from the center of the vehicle in the width direction,
A gas cylinder for storing compressed natural gas as fuel for the engine is arranged on the roof, and the center of gravity of the entire gas cylinder is offset from the center toward the entrance.

That is, since the engine mounted on the bus is arranged with its center of gravity offset to the opposite side of the entrance from the center of the vehicle in the width direction, the floor near the engine in the vehicle width direction can be easily set low. By providing the entrance close to the floor, it is possible to reliably improve the getting on and off from the entrance and exit,
Since the gas cylinder for storing the compressed natural gas of the on-board engine fuel is arranged on the roof of the vehicle, there is no danger that the lowering of the floor will be hindered as described above,
Since the center of gravity of the entire gas cylinder is offset from the center of the vehicle in the width direction to the side opposite to the center of gravity of the mounted engine, the load difference between the left and right wheels due to the offset arrangement of the mounted engine can be reliably reduced. it can.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The embodiments of the present invention shown in the drawings will be described below. The route bus 1 is provided with entrance doors 2, 3, and 4 at a front portion, a middle portion, and a rear portion on one side of a center in the width direction of the vehicle, respectively, and is opposite to the entrance doors 2, 3, and 4 with respect to the center. The engine 5 is mounted on the rear end of the vehicle so that the center of gravity is offset to the side, and as shown by the hatched portion in FIG. Low floor 7 extending from the door to the door 3 at the rear of the vehicle in contact with the door 3 at the center of the vehicle
Is provided. Reference numeral 8 denotes a radiator connected to the engine 5 by upper and lower hoses.

A plurality of gas cylinders 9 for storing compressed natural gas as fuel for the engine 5 are provided on the roof 1 of the bus 1.
By being appropriately fixed to a bracket (not shown) mounted on the top of the vehicle 1 with a clamp, a band, or the like, each of the gas cylinders 9 is disposed on the roof 10 in the front-rear direction of the bus 1, and the center of gravity of the plurality of gas cylinders 9 is determined by the width of the vehicle It is configured to be offset to the same side as the doors 2, 3, 4 with respect to the direction center, that is, to the side opposite to the center of gravity of the engine 5 with respect to the center.

Further, the roof 10 is provided with a lid 12 which can be opened and closed from the indoor side, near a main valve 11 having a built-in overflow prevention valve attached to the rear end of the gas cylinder 9. , The main valve 11, and the lid 12 are entirely covered from above, and a substantially symmetric cover member 13 is provided on the left and right sides of the vehicle body. The gas cylinder 9
The safety valves 14 attached to the front, rear, and side portions are opened at a predetermined temperature or higher and a predetermined gas pressure or higher, and a side safety valve (not shown) can improve thermal responsiveness.

In the bus 1, the engine 5 is mounted at the rear end of the vehicle with its center of gravity offset to the opposite side of each of the doors 2, 3, and 4 with respect to the center in the width direction of the vehicle.
As described above, the low floor surface 7 can be formed widely in the vehicle cabin from the entrance door 2 at the front of the vehicle to the entrance door 4 at the rear of the vehicle, and the getting-on / off properties from the entrance doors 2, 3, and 4 can be improved. Since the gas cylinder 9 for storing the compressed natural gas, which is the fuel of the engine 5, is disposed on the roof 10, the formation of the low floor surface 7 is not hindered at all. By purifying the exhaust gas, the pollution of the bus 1 can be reduced.

Further, since the center of gravity of the plurality of gas cylinders 9 is offset to the opposite side of the center of the vehicle in the width direction of the vehicle from the center of gravity of the engine 5, a large load difference between the right and left rear wheels due to the offset arrangement of the engine 5 is provided. However, the offset arrangement of the entire gas cylinder 9 in the opposite direction to the engine 5 and the weight of the entire gas cylinder 9 significantly reduce or
The vertical distance from the contact surface of the front and rear wheels to the position of the center of gravity of the entire gas cylinder 9 is much larger than the vertical distance from the contact surface to the position of the center of gravity of the engine 5. The imbalance caused by turning the bus 1 due to the offset arrangement can be efficiently suppressed by the reverse offset arrangement of the entire gas cylinder 9, and therefore, it is ensured that a large load difference occurs between the left and right rear wheels of the bus 1. This has the advantage that it is possible to equalize the wear of the rear tires on the left and right, and at the same time it is possible to use the same bus and tires whose center of gravity of the engine is located substantially at the center between the left and right rear wheels.

Further, the lid 1 provided on the roof 10
By opening the valve 2 from the indoor side as shown by the two-dot chain line in FIG. 1, the main valve 11 attached to the rear end of the gas cylinder 9 can be easily operated from the indoor side. After the check valve is closed urgently when the gas fuel passage is broken,
It is very easy to close the main valve 11 once to restart the overflow prevention valve, and also to restart the main valve 11 to use the compressed natural gas in the gas cylinder 9 as fuel for the engine 5. And the maintenance and inspection work of the main valve 11 can be easily performed from the indoor side if necessary. The gas cylinder 9, the main valve 11, and the lid 12 on the roof 10 are covered by a cover member. 13, the above operation and maintenance work of the main valve 11 can be performed without any trouble even when it rains, and each gas cylinder 9 on the roof 10 is completely covered by the cover member 13. Because it is covered by
There is an advantage that the appearance of the bus 1 can be prevented from being particularly impaired, and an increase in air resistance during traveling of the bus 1 can be easily suppressed, so that the fuel efficiency of the engine 5 can be reliably reduced.

In the above embodiment, the gas cylinder on the roof is arranged in the front-rear direction of the bus. However, this gas cylinder is arranged in the vehicle width direction so that the center of gravity of the entire gas cylinder is positioned with respect to the center of the vehicle in the width direction. Even if it is configured to be on the same side as the entrance / exit, that is, on the opposite side to the center of gravity position of the engine that is arranged offset to the opposite side to the entrance / exit with respect to the center, the same operation and effect as the above-described embodiment can be obtained. It goes without saying that you can play.

[0014]

In the bus according to the present invention, the on-board engine is disposed with the center of gravity offset to the opposite side of the entrance from the center of the vehicle in the width direction, and the engine is located close to the engine in the vehicle width direction. Since the floor surface can be easily set low, getting on and off from the vicinity can be easily improved, and even if compressed natural gas is used as the fuel for the engine, the gas cylinder is not Since it is located on the roof, the floor is not lowered at all, and the center of gravity of the entire gas cylinder is offset from the center of the vehicle in the width direction to the opposite side of the mounted engine, Since the load difference between the two wheels can be reliably reduced, the tire wear between the right and left wheels can be made uniform, and the center of gravity of the engine is almost at the center between the left and right wheels. There are excellent advantages can be made common position to the bus and the tire.

[Brief description of the drawings]

FIG. 1 is a schematic longitudinal sectional view of a main part in an embodiment of the present invention.

FIG. 2 is a schematic rear view of a main part in the embodiment.

FIG. 3 is a schematic top view of a main part in the embodiment.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Bus 2, 3, 4 Getting on and off door 5 Engine 7 Low floor surface 9 Gas cylinder 10 Roof 13 Cover member

Claims (1)

[Claims] An engine is mounted so as to offset a center of gravity to a side opposite to a doorway with respect to a center in a width direction of a vehicle, and a gas cylinder for storing compressed natural gas as fuel of the engine is arranged on a roof, A bus configured such that the center of gravity of the entire gas cylinder is offset from the center toward the entrance.