The present invention relates to a bus in accordance with the preamble to the main claim.

A known practice in passenger vehicles and trucks is that a compressor unit forming part of an airconditioning system for their interior is driven by their engines. This compressor unit has consisted of a so-called AC compressor and has been arranged on a bracket fastened to the end of the engine which incorporates the transmission which forms part of the engine. The AC compressor has been driven directly from the engine crankshaft by a belt, usually a V- belt.

It has not been possible to apply this solution to engines for driving large heavy buses with large passenger accommodation, since the compressor unit in such buses would have to be of considerable size and weight to be able to deliver the power needed for such an airconditioning system.

There is no room for a large AC compressor or a number of small compressors within reasonable distance from the engine crankshaft, and hence no possibility of connecting a bracket supporting the compressor unit reasonably securely to the engine block. This has particularly been the case where the engine, as is usual in buses of this kind, also supports and drives by belts from the crankshaft one or more electricity generators of considerable size which are necessary for the relatively large electricity consumption exhibited by such a bus with airconditioning system. The compressor unit has therefore been placed on the bus frame as close to the engine as possible, to enable the unit to be belt-driven. This still results, however, in a relatively long belt drive with belt tension problems due to various movements between the engine and the chassis, while at the same time the installation of the belt drive arrangement and the compressor unit has to take place as a separate operation

after the complete fitting of the engine and other drive units in the bus.

The invention has the object of making it possible to fit the engine which powers the vehicle, preferably a so-called heavy bus, with one relatively large or a number of small AC compressors without the latter being too far from the engine crankshaft or requiring unreasonably robust supporting brackets. A further aim of the invention is to make possible a compact engine unit, including arrangements for driving both electricity generators and AC compressors, in order to facilitate the subsequent mounting of a vehicle body on a chassis equipped with the engine unit.

Brief description nf hp invpn inn

These objects are achieved according to the invention by what is indicated in the characterising part of the main claim.

Using a conventional engine whose cylinders are placed in line in a plane which is set at a relatively large angle makes it possible to free space in order to be able to fasten both the compressor unit and the generator unit to the upward facing side of the engine. If this is done within an angular range delineated from the engine cylinder plane relative to the crankshaft centre, the result is relatively short lever arms for fastening the brackets of these units to the engine. It also makes it possible to gain space for arranging the drives of one or more electricity generators in the space between the compressor unit and the tilted engine block.

In a preferred embodiment of the invention the engine is angled at between 40° and 60° to a vertical plane through the crankshaft centre. Also, the angle at the crankshaft centre between the cylinder plane and the centre of gravity of the compressor unit, which is situated on the opposite side of said vertical plane, is between 60° and 120°. This makes

possible a compact engine unit incorporating an AC compressor drive which is suited to, and easy to install in, a space-optimised bus chassis.

In another embodiment of the invention the electricity generator unit is situated within an angular range which at the crankshaft centre extends from the engine cylinder plane to the plane through the engine crankshaft and which includes the centre of gravity of the compressor unit. The result is a compact engine unit incorporating the belt drives not only for one or more AC compressors but also for one or more electricity generators in such a way that the belt drives are within a limited but well-utilised area on the endwall of the engine. It also makes it relatively easy to use parts of the auxiliary unit arrangement which is already applied to engines suited to other vehicle applications such as truck operation.

Other features distinguishing the invention are indicated in the attached patent claims and the description below of an embodiment of the invention.

T.iπt-. of drawings

An advantageous embodiment of the invention is described below with reference to the attached drawings, which are as follows:

Figure 1 depicts schematically a bus according to the invention,

Figure 2 shows a view from above of the rear section of the bus depicted in Figure 1 and

Figure 3 shows a schematic end view of a drive engine forming part of a bus according to Figures 1 and 2.

Dpsrrri p i nn nf an pmh irH m n Expressions used in this description with regard to directions such as in front, forward, front, rear, behind, rearward, right and left are all referred to the direction of forward movement of the bus unless otherwise indicated.

A two-axled bus depicted in Figure 1 is a so-called heavy bus intended for relatively large numbers of passengers. The right side of the bus exhibits passenger doors forward of the front axle 1 and, in an urban bus version also between the front axle 1 and the rear axle 2. Rearward of the rear axle 2 the bus is also provided with a passenger door 3 leading to a standing area 4 which is indicated in the cutaway rear section of the bus in Figure 1 and in Figure 2.

The bus's drive unit, including its auxiliary units, is situated in a space 6 under a passenger bench seat 7 (arranged in the extreme rear of the bus) and in a tower- like space 8 beside the bench seat 7 in the rear right corner of the bus. The space 6 extends across substantially the whole width of the bus and is limited rearwards by the rear wall 9 of the bus and forwards and upwards by substantially vertical walls and horizontal planes which are connected to the bench seat 7. The space 6 also has a connection with the rear axle 2 via a space situated along the left side of the bus. The drive unit's engine and gearbox with a bevel gear are accommodated in the space 6, while the engine's radiator device is arranged in the tower space 8 above the righthand end of the engine. The drive unit is consequently installed with the engine crankshaft transverse to the forward direction of the bus.

The engine 20, the righthand end of which is depicted in Figure 3, is a so-called in-line engine, i.e. it has a number of cylinders (not depicted) placed in a row. The engine 20 is installed in the space 6 at a large angle, between 40° and 60°, to a vertical plane 57 through its crankshaft centre 55 so that its cylinders have their extent along a plane 46. The forward upward facing side of the engine incorporates parts belonging to the inlet system, while the rear downward facing side incorporates parts of the engine exhaust system, particularly its exhaust

manifold. The upper part of the cylinders is close to the bus's rear wall 9. In a conventional but here undepicted manner, the cylinders are covered by a cylinder head with inlet and outlet ports, valve mechanisms and injection parts. This is covered outside by one or more valve covers 47 which in this case is the engine component which extends furthest rearwards.

The engine's righthand end depicted in Figure 3 is situated directly inside the right side of the bus and includes on the end of the engine crankshaft a vibration damper 30 and, furthest out, a separate belt pulley 31. A drive belt 32, advantageously of the poly-V type, cooperates with a belt drive section (not depicted) on the periphery of the vibration damper. The belt drive 32 runs round more than 180° of the periphery of the vibration damper and transmits driving power to a compressor unit 33 (consisting in this embodiment of two compressors) forming part of an airconditioning system intended for the bus's passenger space. The compressors 33 each have a belt pulley 34 cooperating with the belt 32.

Other parts belonging to the airconditioning system are advantageously arranged in or on the roof of the bus as close to the compressor unit as possible, but as that system does not form part of the present invention no further description of it is given here.

Adjacent to the endwall of the engine, an intermediate pulley 24 is mounted on a spindle in order to move along a circular arc. This intermediate pulley 24 is spring-loaded against the belt 32 in order to keep the latter taut and create a sufficient winding angle for the belt 32 for its cooperation with the vibration damper 30 and the belt pulleys 34 of the compressors 33. The intermediate pulley 24 also makes it possible to fit the belt 32.

A second driving belt 40, likewise advantageously of the poly-V type, cooperates with the belt pulley 31 to drive at least one electrical generator unit 50 (consisting in this embodiment of two generators) fastened to the engine. The belt 40 also drives, via a belt pulley 41, a coolant pump arranged on the engine and also runs over fixed intermediate pulleys 42, 43 and a spring-loaded swingingly mounted intermediate pulley 44 of the same type and with the same function as the intermediate pulley 24.

The compressors 33 are arranged horizontally side by side and fastened to a bracket 45 which is itself fastened to the rearward and upward facing side of the engine. In this embodiment the bracket 45 is also arranged to support adjacent to the engine endwall the bearing of the spring- loaded intermediate pulley 24. To keep the forces on the bracket and its fastening within reasonable limits it is advantageous if the compressors' common centre of gravity 56 is within an angular range of 0 to 60° to the vertical plane 57 through the engine crankshaft centre 55. Space is also created for installing other auxiliary units connected to the engine if the angle at the engine crankshaft centre between the cylinder plane and the compressor's centre of gravity is between at least 60° and 120°.

It is also advantageous to arrange the electricity generators 50 (belt-driven from the crankshaft) within an angular range between the engine cylinder plane 46 and the plane which includes the centre of gravity of the compressors 33 as seen from the crankshaft centre 55. This makes possible a compact drive unit which can already during bus chassis manufacture be equipped with airconditioning compressors and electricity generators and their drives. This facilitates the bus's final completion by the body being mounted on the chassis.

Also, the resiliently mounted intermediate pulley 24 cooperating with the compressor drive belt 32 is situated

outside the two areas limited by the compressor drive belt 32 and the generator drive belt 40. Said intermediate pulley 24 is also mounted, however, as seen in the end plane of the engine, within an angular range between the engine cylinder plane 46 and the plane 58 which includes the compressors' centre of gravity 56 as seen from the crankshaft centre 55. This results in effective utilisation of the space available adjacent to the endwall of the engine for arranging the intermediate pulleys and belt pulleys which cooperate with the belts 32, 40.

The effects aimed at by the invention are of course also achieved in a largely similar manner if the positions of the compressor unit 33 and the electricity generator unit 50 are reversed.