GB2188963A

GB2188963A - Improvements in or relating to road sweeping vehicles

Info

Publication number: GB2188963A
Application number: GB08609016A
Authority: GB
Inventors: Anthony James Duthie; Michael Sandford
Original assignee: JOHNSTON ENG Ltd
Current assignee: JOHNSTON ENG Ltd
Priority date: 1986-04-14
Filing date: 1986-04-14
Publication date: 1987-10-14
Also published as: US4773119A; EP0242943A2; DE3767012D1; EP0242943A3; EP0242943B1; GB2188963B; GB8609016D0

Description

GB2188963A 1

SPECIFICATION under conditions of maximum drive speed.

Conveniently the vehicle includes access Improvements in or relating to road sweep- ports through which the fluid level in the fluid ing vehicles coupling may be externally monitored. An ad 70 vantage of this is that the drive train compo This invention relates to road sweeping nents need only be separated when major vehicles of the suction type. overhaul is required and routine maintenance Such vehicles are known in which the ex- will generally be limited to checking the fluid hauster fan generates a vacuum within an air level through an access port.

tight container mounted on the vehicle chassis 75 A specific embodiment of the invention will and debris from the road is sucked through now be described by way of example only suction conduits connected to the container. and with reference to the accompanying draw In addition to the propulsion unit of the ings of which vehicle an auxiliary engine is provided for driv- Figure 1 is a schematic sectional elevation ing the suction fan and sweeping machinery. 80 of the engine, drive train and fan of a road The fan and engine are typically connected sweeping vehicle, by a drive train which includes a centrifugal Figure 2 is a schematic perspective part cut clutch or drive belts or rubber couplings. A away view of a road sweeping vehicle and problem exists with such drive trains in that Figure 3 is a sectional elevation showing de they possess elastic properties which can re- 85 tails of the drive train of Fig. 1.

sult in torsional vibration excited by the en- The road sweeping vehicle 1 of Fig. 2 com gine's torsional and cyclic vibration character- prises a self propelled chassis 2 on which is istics particularly during acceleration or decel- carried an air tight container 3. An auxiliary eration of the drive when critical speeds may engine 4 is mounted on the chassis 2 for be endured. Consequently it has been found 90 driving a suction fan and sweeping machinery.

that in order to reduce vibration and the ef- Suction conduits (not shown) beneath the fects of shock it has been necessary to use a vehicle operate in conjunction with the sweep fan with a lowest moment of inertia practicing machinery to collect debris which is able. Since the fan is subjected in use to im- sucked into the container 3.

pacts and erosion from particles of debris 95 Fig. 1 shows the engine 4 which is a four there have been difficulties in achieving fan cylinder diesel engine having a flywheel 5 con constructions which are both sufficiently ro- nected to the engine's output shaft 6. A fluid bust and sufficiently low in moment of inertia. coupling 7 within the flywheel 5 couples the According to the present invention there is drive from the flywheel 5 to a gearbox input disclosed a suction type road sweeping 100 shaft 8 of a step up gearbox 9 having an vehicle comprising a self propelled chassis, an output shaft 10 driving a centrifugal fan 11.

air tight container mounted on the chassis, at The engine 4 also drives a conventional en least one suction conduit connected to the gine cooling fan 12 providing air flow through container, a fan for generating a vacuum in a radiator 13 as shown in Fig. 2. The engine the container by extracting air through an out- 105 also has a pulley drive 14 for driving a water let duct, an engine for driving the fan and a pump supplying water for dust suppression drive train communicating between the engine sprays around the sweep gear (not shown). A and the fan wherein the drive train includes a hydraulic pump 16 is driven by the engine's fluid coupling. power-take-off facility and this provides hy- An advantage of using a fluid coupling is 110 draulic power to the sweep gear.

that it is substantially free of elastic properties The centrifugal fan 11 is located in a fan in transmitting torsional drive and also such housing 17 and expels air from the container couplings have a considerable affinity for ab- 3 through an outlet duct 18.

sorbing torsional shock. In Fig. 3 a flywheel housing 19 contains the Preferably the fluid coupling and the engine 115 flywheel 5 which has an oil filled chamber 20 flywheel are of integral construction. within which a driven plate 21 of the fluid Conveniently the drive train comprises a coupling 7 is rotatable. Torque for the engine fluid coupling within the engine flywheel, an is transmitted across an oil filled interface 22 output shaft of the coupling connected to the from the flywheel 5 to the driven plate 21 so input of a step up gearbox and an output 120 as to drive the gearbox input shaft 8 which is shaft of the gearbox connected to the fan. splined to the driven plate 21.

Conveniently the fluid coupling and the gear- The flywheel housing 19 is extended by a box are housed in a common housing con- gearbox housing 23 containing a step up gear nected to the engine. box 9 having an output shaft 10 on which is It is possible to construct a fan of a more 125 mounted the centrifugal fan 11.

robust design than has been hitherto possible Upon starting the engine 4 the flywheel 5 without incurring the penalty of vibration or rotates and torque is transmitted to the driven shock damage to the drive train. plate 21 across the oil filled interface 22.

Preferably the fluid coupling provides slip- Drive is transmitted to the centrifugal fan 11 page in the drive train of not more than 5% 130 which begins to rotate. Some slippage in the 2 GB2188963A 2 drive train comprising the flywheel 5, fluid any preceding claim including access ports coupling 7, at gearbox 9 is experienced parti- through which the fluid level in the fluid cou cularly at engine idling speeds due to the in- pling may be externally monitored.

herent properties of the fluid coupling. How- 8. A road sweeping vehicle substantially as ever as the engine is accelerated to full power 70 hereinbefore described with reference to and the torque transmitted by the fluid coupling 7 as shown in the accompanying drawings.

is such that slippage is reduced to less than 5%. Printed for Her Majesty's Stationery Office by Burgess & Son (Abingdon) Ltd, Dd 8991685, 1987.

In a particular example a fan of 725mm dia- Published at The Patent Office, 25 Southampton Buildings, meter and 8Omm depth includes 16 blades. London, WC2A l AY, from which copies may be obtained.

At engine speeds of 1500 rpm and 1800 rpm the fan speed was greater than 2620 rpm and 3150 rpm respectively using a gearbox ratio of 1A.79. This represents a nominal slippage of 2.5 To reduce the effects of engine vibration to a minimum only the engine, the drive train and the fan are live mounted whilst the radiator 13, the fan housing 17 and the water pump 15 are separately mounted away from the engine.

Since the fan 11 will encounter impacts and abrasion from residual debris in the exhausted air, the fan can now be of an advantageously heavy duty construction with self cleaning abrasion resistant blades due to the fact that the fan design is no longer subject to the constraint of moment of inertia matching to the engine's torsional and cyclic vibration characteristics.

Claims

1. A suction type road sweeping vehicle comprising a self propelled chassis, an air tight container mounted on the chassis, at least one suction conduit connected to the container, a fan for generating a vacuum in the container by extracting air through an outlet duct, an engine for driving the fan and a drive train communicating between the engine and the fan wherein the drive train includes a fluid coupling.

2. A road sweeping vehicle as claimed in claim 1 wherein the fluid coupling and the en- gine flywheel are of integral construction.

3. A road sweeping vehicle as claimed in claim 2 wherein the drive train comprises a fluid coupling within the engine flywheel, an output shaft of the coupling connected to the input of a step up gearbox and an output shaft of the gearbox connected to the fan.

4. A road sweeping vehicle as claimed in claim 3 wherein the fluid coupling and the gearbox are housed in a common housing connected to the engine.

5. A road sweeping vehicle as claimed in any preceding claim wherein the moment of inertia of the fan is substantially greater than that of the flywheel.

6. A road sweeping vehicle as claimed in any preceding claim wherein the fluid coupling provides slippage in the drive train of not more than 5% under conditions of maximum drive speed.

7. A road sweeping vehicle as claimed in