GB2159918A

GB2159918A - Driving coupling assembly

Info

Publication number: GB2159918A
Application number: GB08413449A
Authority: GB
Inventors: Ian Charles Smith; Gordon Harvey
Original assignee: A Smith Gt Bentley Ltd
Current assignee: A Smith Gt Bentley Ltd
Priority date: 1984-05-25
Filing date: 1984-05-25
Publication date: 1985-12-11
Also published as: GB8413449D0; GB2159918B

Abstract

A drive coupling assembly permitting lateral transfer of rotary drive from an engine to a machine without side loads being imparted to the engine output shaft comprises a cup-shaped support 13 bolted to the engine flywheel housing 11 and having a base wall from which a shaft 17 projects inwardly of the support, co- axial with the engine shaft. Rotatably mounted on that shaft 17 is an output member 29, such as a toothed belt pulley, connected to the engine shaft by means of a resilient coupling. The sideways load of the belt drive 33 is thus transferred to the flywheel housing through the support, the engine shaft being relieved of all side-thrust. <IMAGE>

Description

SPECIFICATION Drive coupling assembly This invention relates to a drive coupling assembly suitable for use for example in taking a drive from an internal combustion engine, such as a diesel engine.

Internal combustion engines are often used to power various kinds of machinery other than vehicles for example, electrical generators and air compressors. Very often, the machine to be driven by the internal combustion engine is mounted on the same bed as is the engine, such that the machine input shaft is substantially co-axial with the internal combustion engine output shaft, an appropriate coupling being provided to transfer the drive from the engine to the machine. Such in-line installations are relatively cheap to implement, but suffer from the disadvantages that the installation has a most considerable overall length, and that unless expensive gear boxes are provided, the machine is rotated at the same speed at that at which the engine turns.

Space requirements often dictate that the machine to be driven by the engine must be mounted alongside the engine itself, the machine being driven by a suitable drive train from the engine output shaft, such as by a belt or chain. Apart from the reduction in overall length, leading to a more compact installation, such a side-by-side arrangement has the added advantage that the drive ratio between the engine output shaft and the machine input shaft can be varied atwill-for example by changing the pulley or sprocket sizes of the drive train. This has particular benefits in the case of a diesel generator set, for the standard speeds for generators are 1500 and 3000 rpm, though better efficiencies can be obtained at the lower speed, but diesel engines are more efficient at speeds between these two values.Better efficiencies can be obtained with a generator running at 1500 rpm, but since this speed is too slow for a diesel engine, most in line-diesel generator sets are run at 3000 rpm. With however a belt-driven side-by-side configuration, the pulley sizes may appropriately be selected for the engine output shaft and the generator input shaft whereby the diesel engine runs at says 2200 rpm and the generator at 1500 rpm.

Notwithstanding the advantages mentioned above for a side-by-side configuration for a generator set, taking the drive other than co-axially from the crankshaft of the engine may give rise to considerable problems, in view of the side loads which a belt or chain drive will impart on the engine crankshaft. With some engines, such side loads are totally prohibited, whereas with other engines limited side loads are permitted, but then usually only in certain specified directions. For such cases, it would be necessary to provide a separate idler assembly mounted on the same bed as supports the engine and which had a drive pulley for the machine, the assembly being coupled to the engine output shaft in such a way as to impart side loads thereto.This invention aims at providing an improved form of drive assembly suitable for use for example with an internal combustion engine so as to permit the crankshaft thereof to transfer power to a drive train such as a belt or chain drive without side loads being imparted to the crankshaft.

Accordingly, this invention provides a drive coupling assembly for a drive shaft projecting from an engine, which assembly comprises a cup-shaped support having a base wall and a side wall upstanding from the base wall, the end of the support remote from said base wall being adapted for mounting on the engine, a bearing shaft carried by the base wall of the support and projecting internally thereof such that when the support is mounted on the engine said bearing shaft is substantially co-axial with the engine drive shaft, a drive out member rotatably mounted on the bearing shaft, and a coupling adapted drivinglyto couple the drive shaft to the drive output member, the side wall of the support having a cut-out portion to permit access to the drive output member by a drive train.

It will be appreciated that when the drive coupling assembly of this invention is used with an internal combustion engine, the drive shaft would comprise the projecting portion of the crankshaft which is consequently relieved of all side loads which otherwise would have been imparted thereto by the use of a belt or chain to drive a machine. For such an arrangement, the cup-shaped support is mounted directly on the engine block and transfers all side loads directly to the block, without subjecting the projecting portion of the crankshaft to any side loads.

Particularly for the case of a diesel engine, it is preferred for the coupling which is adapted drivingly to couple the drive shaft to the drive output member to be in the form of a resilient shockabsorbing coupling, so as to smoothen the drive from the engine to the other machine to be driven, and to dampen any torsional vibrations. For example, the drive coupling may comprise a pair of flanges one adapted for connection to the engine crank shaft (by being bolted for instance to the engine flywheel) and the other connected to the drive output member, and a resilient block-for example of a natural or synthetic elastomer -- being disposed to impart drive from the one flange to the other.

Most preferably, the drive output member is in the form of a toothed-belt pulley adapted for use with a toothed belt thereby to impart drive without slippage to another toothed pulley, mounted on the input shaft of some other machinefor example, a generator. The side wall of the cup-shaped support serves to hold the base wall of the support at a suitable position spaced axially of the engine drive shaft but with the bearing shaft co-axial therewithin, in such a manner as to be capable of carrying the side loads imparted to the support bearing shaft and transferring those loads to the engine. Thus, the side wall may be generally cylindrical, or may be conical, or may take any other appropriate form which generally encircles the drive output member.

Most conveniently, the end of the side wall remote from the base wall is provided with an outwardly directed flange having spaced mounting holes therearound, whereby the support may be bolted to a suitable part of the engine. For example, in the case of a diesel engine, the support may conveniently be bolted to the flywheel housing of the engine.

The base wall of the support advantageously is bolted to the side wall thereof, by means of a ring of bolts extending through the ball wall and into threaded holes provided in an inwardly-directed flange of the side wall. The bearing shaft may be attached to the base wall for example by means of a welding technique, or may be formed integrally therewith, for example as a one-piece forging.

The output drive member may be mounted on the bearing shaft in any suitable manner having regard to the relative rotation therebetween and the side loads to be imparted on the drive output member.

Preferably therefore the drive output member is rotatably mounted on the bearing shaft by means of one ball race and one roller race, the formerto provide axial location of the drive output member and the latter to assist with the transfer of the side th rust to which the drive output member is subjected.

The cut-out in the side wall of the support should be provided in such a way as to permit drive to be taken from the drive output member. In the case of a toothed belt drive, two cut-outs may be provided, one for each run of the belt, provided always that the configuration is such that the belt may be fitted to the drive output member, and replaced when necessary.

By way of example only, one specific embodiment of this invention will now be described in detail, reference being made to the accompanying drawings, in which: Figure lisa general perspective view of the completed drive coupling assembly of this invention, as fitted to the output shaft of a diesel engine; and Figure 2 is a vertical section taken through the drive coupling assembly of Figure 1.

The embodiment of drive coupling assembly of this invention is intended for use in the construction of a diesel generator set, where the generator is to be mounted alongside the diesel engine with the drive to the generator being by way of a toothed belt, from a toothed pulley driven by the diesel engine. Part of the block of the diesel engine is shown at 10 in the drawings, there being a flywheel housing 11 bolted to the block 10 so as to surround the engine flywheel 12.

The drive coupling assembly 13 of this invention comprises a cup-shaped support having a generally cylindrical wall 14 provided with an outwardly directed flange 15 at one end; the flange is bolted to the flywheel housing 11 by means of bolts 16 passing through holes provided in the flange. The other end of the generally cylindrical wall 14 is turned inwardly and has a support base wall attached thereto by means of bolts 17, the base wall having a bearing shaft 18 welded thereto so as to project generally co-axially with the engine flywheel, internally within the cup-shaped support.

The bearing shaft 18 carries a ball race 19 and a roller race 20, clamped in position by means of a distance piece 21, cap 22 and bolt 23. Rotatably mounted on the races 19 and 20 is a carrier 24, bolted together from a central portion 25, end plate 26 and coupling half 27. Mounted within the end plate 26 and the coupling half 27 are oil seals 28. A toothed-belt pulley 29 is fitted on the central portion 25 of the carrier 24, three grub screws 30 being provided to lock the pulley 29 to the carrier 24, for simultaneous rotation.

The coupling half 27 comprises one part of a known form of resilient coupling, such as a coupling as is sold by Holset underthe name 'SB Range'. The other half of the coupling is shown at 31, and is bolted co-axially to the engine flywheel 12, for rotation therewith. Disposed between the two coupling halves 27 and 31 is a resilient rubber connecting block 32, arranged to permit torque to be imparted between the two coupling halves, whilst giving damping characteristics to assist the absorption of shock loading and torsional vibrations.

As is illustrated in Figure 1, drive is taken from the toothed belt pulley 29 by way of a toothed belt 33, passing through a cut-out 34 in the generally cylindrical wall 14 of the support. Such a cut-out portion may be provided at an appropriate position, to permit the drive to be taken in the appropriate direction for the machine to be driven by the diesel engine.

It will be appreciated that when in use, the drive coupling assembly of this invention serves wholly to isolate an engine crankshaft from side loads, and transfers such side loads as arise from the drive train directly to the engine block 10. Servicing of the assembly is moreover relatively simple, for all that is necessary is for the tension to be relieved from the drive belt 33, whereafter the bolts 17 are removed to permit the withdrawal of the base wall 16, together with the complete bearing assembly except for coupling half 31. Should therefore for example the resilient block 32 fail, its replacement is a relatively simple matter, as compared to a case where a generator is driven co-axially from a diesel engine, where separation of the two major components may be necessary in order to service the coupling.

Claims

1. Adrive coupling assembly for a drive shaft projecting from an engine, which assembly comprises a cup-shaped support having a base wall and a side wall upstanding from the base wall, the end of the support remote from said base wall being adapted for mounting on the engine, a bearing shaft carried by the base wall of the support and projecting internally thereof such that when the support is mounted on the engine said bearing shaft is substantially co-axial with the engine drive shaft, a drive output member rotatably mounted on the bearing shaft, and a coupling adapted drivinglyto couple the engine drive shaft to the drive output member, the side wall of the support having a cutout portion to permit access to the drive output member by a drive train.

2. A drive coupling assembly according to claim 1, wherein the coupling which is adapted drivingly to couple the drive shaft to the drive output member comprises a resilient shock-absorbing coupling.

3. A drive coupling assembly according to claim 2, wherein the drive coupling comprises a pair of flanges one adapted for connection to the engine drive shaft and the other connected to the drive output member, and a resilient block disposed to impart drive from the one flange to the other.

4. A drive coupling assembly according to any of the preceding claims, wherein the drive output member is in the form of a toothed-belt pulley adapted for use with a toothed belt thereby to impart drive without slippage to another toothed pulley, mounted on the input shaft of a machine to be driven.

5. A drive coupling assembly according to any of the preceding claims, wherein the side wall of the support generally encircles the drive output member, except where the cut-out portion is provided, and the end of the side wall remote from the base wall is provided with an outwardly-directed flange having spaced mounting holes therearound.

6. A drive coupling assembly according to any of the preceding claims, wherein the base wall of the support is removably fastened to the side wall thereof, the bearing shaft being attached to the base wall centrally thereof to project inwardly of the support.

7. A drive coupling assembly according to any of the preceding claims, wherein the drive output member is rotatably mounted on the bearing shaft by means of one ball race and one roller race, the former to provide axial location of the drive output member and the latter to assist with the transfer of side thrust from the drive output member to the shaft.

8. A drive coupling assembly according to any of the preceding claims and adapted for use with a belt drive, wherein two cut-out portions are provided in the cup-shaped support, one for each run of the belt.

9. A drive coupling assembly substantially as hereinbefore described with reference to and as illustrated in the accompanying drawings.