GB2179604A - Compact vehicle drive unit - Google Patents

Abstract

An integrated power unit has its cylinders 7 inclined above the transmission system 2 which provides output drive along the final drive axis 3. This axis coincides with the plane 12 of the cylinder head joint, permitting simplified construction. The unit may be installed transversely in a vehicle in a laterally symmetrical manner, driving equal length output shafts, with suspension systems as also disclosed herein attached directly to its casings, and with the resultant assemblage flexibly mounted to the vehicle in a manner also disclosed. In a rear drive vehicle the induction manifold 23 lies beneath the boot floor. The clutch (not shown) is mounted on the gearbox mainshaft axis 4, driven from the crankshaft 14 by a primary drive having two gears only (not shown), and an arrangement of multi-speed transmission gearing along axes 3,4 and 5 is also disclosed which provides a number of direct drive paths. <IMAGE>

Description

SPECIFICATION Compact drive unit This invention relates to an integrated automotive power unit, comprising a reciprocating piston internal combustion engine, a gearbox and final drive gearing and to an associated suspension and mounting arrangement.

The integration of engine, gearbox and final drive into a single unit located adjacent to the driven wheels, is an established automotive design technpique which tends to result in reduced weight and cost, and improved transmission efficiency. The placementofthe unit in a transverse position (ie.

with the crankshaft parallel with the virtual axles of the car) is also well established and tends to result in more efficient space utilisation within the vehicle envelope, with further improvement in transmission efficiency due to the elimination of a right-angle drive.

Most existing arrangements of transverse power units fall into two basic categories. Firstly, those with the engine placed mainlyabovethetransmission components, but substantially central within the width ofthe vehicle, and secondly, those where the transmission is to one end ofthe engine crankshaft, such that the whole forms an assembly which is assymmetric relative to the vehicle longitudinal centre line, with the result that, unless special measures are taken, the drive shafts to the two wheelswill be of unequal length.

Such power units are more commonly intended for applications in vehicles driven through their front wheels, and such as passenger saloon cars of small to medium size. However, with rising powerto weight ratios, front wheel drive becomes increasingly undesirable due to considerations oftraction, and therefore, particularly in cars of higher performance, an integrated power unit located adjacent to the rear wheels may be more advantageous.

Various drawbacks and limitations are apparent in existing transverse power unit designs, particularly with regard to rear drive applications.

In passenger saloon cars, and more particularly those of the so called 'hatchback' variety, and in estate car derivatives, where it is desirable that the passenger compartment should be freely interconn ectable with the rear luggage compartment, such that, by suitable means the entire rear portion of the body may be converted to an unobstructed load carrying space having a substantially flat platform, the existence adjacent to the rear wheels of a power unit ofthe profile typical of existing designs may rendersuch provision ineffectual, especiallywherethe engine is above the transmission. Asimilar drawback applies in the case of commercial vehicles.

Also, in sports cars, wherein the location of an integrated power unit immediately behind the occupants is particularlyadvantageous, both with regardto traction in a high performance application, and also tothe marketing appeal of a configuration akintothat of current racing cars, existing examples serve to illustrate the difficulty of providing adequate luggage capacity anywhere within the vehicle, and also of providing stowage for small items within the passen gercompartment, as is desirable in the interests of convenient usage.The space required to accommo date an efficient induction system to the engine may particularly exacerbate these difficulties. Meanwhile, unless measures are taken to minimise the mass of a rear mounted power unit, vehicle stability and handl ing problems may arise due to an excessive rearward weight bias.

Even in front engine applications, existing transv erse power units, especially those having the engine above the transmission, may suffer a drawback in thatthe height, occurring art a pointfarforward in the vehicle, may impose restrictions on the provision of bodywork having favourable aerodynamic properties.

Afurther consideration in any design incorporat ing an integrated power unit is that additional benefit may derive from mounting the suspension system of the adjacent wheels direct to the power unit, the whole resultant assembly then being flexibly mounted to the vehicle structure. By a suitable selection of mounting flexibilities, the power unit mass may thus be made to act as an effective dynamic absorber of road induced vibrations. Such an arrangement may also permit substantial reductions in weight and cost, providing that it can be achieved with a minimum adjunction of material to the power unit structure, such as brackets and subframes.Also, in rear drive applications, further advantage, particularlyto weight and cost may accrue by utilising the final drive shafts as part ofthe suspension linkage, but this is feasible only where the two shafts are of equal and suitable lengths. Existing power units are not known to have been designed with the above provisions specifically in mind, the requirements of which may be more easily met in arrangements wherethemain enginestructureandthefinaldrive gears are both located substantially central within the width ofthevehicle.

In certain applications, such symmetry may also be desirable for aesthetic or other reasons, such asto permit the use of an engine having more cylinders in line across a vehicle of given width. Also, in front drive applications, the use of an assymetric arrangement wherein the drive shafts to the two wheels are of unequal lengths may result in undesirabledisturb- ances being felt th rough the steering wheel, particularly in more highly powered vehicles.

Afurther drawback of known existing power unit designs, and more particularly off those which do offerthe advantage of substantial symmetry, concerns the efficiency of the geartransmission system. An important consideration in the design of any vehicle transmission gearing isto minimise the total number of gear meshing points between the engine crankshaft and the driven road wheels, since at each meshing point, useful powerwill be lost while unwelcome noise may be generated. This consideration may be regarded as especially cogent in the case of an integrated transverse power unit if full advantage is to be taken ofthe inherent efficiency benefits mentioned in the opening paragraphs.It may be shown of typical existing designs having manually operated gearboxes,thatthe practical minimum total numberofsuch meshing points is two, as is achieved by means of a widely favoured arrangement ofthe assymmetric variety, wherein a gearbox ofthe 'two shaft' (or'all indirect') type is located to the end of the engine, with its input shaft coaxial with the engine crankshaft, drive in each of theforward rations provided then being simply through one of a number of alternatively selectable gear pairs, the only other gear meshing pointoccurring at the final drive gears which normally are additionally provided, both to bring the output to a convenient point and also since the required low ratios cannot usually be provided in a single step.

In power units ofthe more symmetrical variety, where the gearbox input shaft is not co axial with the enginecrankshaft,a primarydrive means must be provided, which maytake the form oftwo or more gears or a chain drive, and which therefore adds a further source of inefficiency.In an existing design of this type, a total oftwo meshing points is again achieved, but only in one of the forward ratios provided, by means of a design where the primary drive consists of a single pair of gears, while the gearbox is of the 'three shaft' (or 'direct top' or 'layshaft') type, such that the input and output shafts are coaxial and maybejoinedtogetherto provide a direct straight through drive as one ofthe selectable ratios, the second meshing pointthen again occurring at the final drive gears which are also provided. However, a drawback ofthis arrangement is that, when any of the otherforward ratios are selected, two additional meshing points occurwithin the gearbox as drive is transferred to and then back from the layshaft.

This disadvantage is more manifest where, in an arrangement ofthis type, it is required to incorporate a gearbox having, for example, five forward speeds, and of the type being increasingly favoured in the interests offuel efficiency where the two highestforward ratios are both intended to be used extensively, since if fourth gear is made 'direct', fifth would involve at leastfourtotal meshing points, and vice versa.

If, in a power unit having primary drive means, a gearbox of the alternative 'two shaft' variety is used, the practical minimum total number of meshing points achievable is three in all gears, one morethan the optimum. Afurther disadvantage of any power unitarrangementutilisinga manualgearboxofthe 'two shaft' variety isthatthis makes it more difficult to provide for the optional employment of an autom aticgearboxofconventional form.

Further concerning existing transmission systems, the number of components, particularly gears, each differentfrom any other, is usually considerable, and the costof manufacture is therefore high.

An aim of the present invention is to provide an improved arrangement for an integrated automotive power unit which includes a reciprocating piston internal combustion engine, a transmission system and all necessary auxiliary equipment, such that the overall profile, particularly as viewed in a direction along the crankshaft axis, is minimised and of a shape suitable, for example, for incorporation into a compact sports car or high performance saloon car wherein drive is to be provided through the rear wheels and wherein a favourable arrangement of passenger and luggage accommodation is to be provided, it being intended that the power unit should be disposed in such application with its crankshaft transverse and its main structure arranged approximately symmetrical with respect to the longi tudinal centre line of thevehicle.Afurther aim ofthe invention is to provide a manually operated geared transmission system arranged so that the connections to the final drive output shafts to the wheels may also be symmetrically disposed with respect to the aforementioned centre line, and also arranged, in the interests of efficiency, such that all shafting is parallel with the crankshaft axis, and such that, in more than one ofthe forward ratios provided, the total number of loaded gear meshing points between the crank shaftandthedriven road wheels is onlytwo,and further arranged such that the cost, particularly ofthe gearelements,maybeminimised. Itis also an aim of the invention to provide an associated suspension system of simple design which may incorporate the final drive output shafts as part of its linkage and which is mounted directly to the power unit so asto form a sub-assemblywhich may be flexibly mounted to the vehicle structure in a favourable manner. The invention further aims to satisfy the requirements of lightness, low cost of manufacture, ease of servicing, structural stiffness, a low centre of gravity, a simple gearchange arrangement and an induction system of favourable form. It is intended that an embodiment of parts ofthe invention should be equallysuitable for vehicles driven through the front wheels or throughfourormorewheels.

With the above aims in view, then, according to the present invention, there is provided an integrated power unit incorporating a reciprocating piston internal combustion engine and atransmission system, in an arrangement where the engine, having a number of cylinders disposed in line, is designed to operate in a position with its crankshaft axis approximately parallel to an adjacentvirtual axle of a motor vehicle, and with its cylinder axes contained in a plane describing an acute angle above the horizontal, such that the crankshaft axis is at a level substantially similartothatofthevirtual axlewhilethecylinder head is located approximately directly overthe virtual axle, and with its cylinders disposed either side ofthe vehicle longitudinal centre line in a subst antially symmetrical manner, and with the transmis- sion being accommodated in the main within casings formed beneath the cylinders such that a section which may lie beneath the central cylinders is extended furthest from the crankshaft and encompasses and axis substantially coincident with the virtual axle at the normal ride height and known as thefinal drive axis, the power unit being designed to be in direct driving communication with the adjacent road wheels through universallyjointed drive shafts whose inner ends are connected with output driving members of the power unit at points which may be symmetrically disposed either side ofthevehicle longitudinal centre line and which lieonthefinal drive axis, which axis may, by virtue of the general arrangement of the power unit, lie ion a plane which also includes a joint face between the cylinder block and cylinder head. These features of the invention afford a particularly compact, favourablyshaped assemblage, advantageous not only spatially, but also to the provision of a power unit casing structure which is light and stiff and suitablefor exampleto act as a stressed member supporting vehicle suspension loadings.

In an embodiment in which the said casing structure is of a preferable design, there is provided a main casing part, formed so asto include cylinder, crankcase and main transmission housings in an integral unit, while there may additionally be provided a combined crankcase and transmission closing part, a final drive covering part, a cylinder head and end covering parts, such provisions affording a structure of particularly high efficiency and low cost, byvirtueofthesmall numberofjointingsinvolved, while atthesametimefacilitating manufacturing and assembly processes.

The crankcase and transmission closing part may adjoin the main casing part in a plane including the crankshaft axis, thereby permitting a favourable design wherein the engine main bearings are provided in housingsdiametrallysplitbythejointface such thatsemi circular portions thereof reside in each ofthe two adjoining casing parts, thisfeature rendering unnecessary the use of separate bearing caps and at the same time providing a particularly rigid means of support for the crankshaft.

Similarly,thefinal drive covering partmayadjoin the main casing part in a plane including the final drive axis, in a design whereby the resultantenclosure constitutes the aforementioned furthest extended section of the transmission housings, and such that the aforementioned power unit output drive members may emerge from the sidewalls ofthe resultant enclosure, and wherein there may be provided within the resultant enclosure, parts centred on the final drive axis and connected with the power unit output drive members, such as a differential and gearing attached thereto, which parts may be supported by bearings provided in housing diametrally split by the jointface such that semi circular portions thereof reside in each ofthe two adjoining casing parts, such a design providing a simple construction of low cost and also a convenient means of assemblyofthefinal drive parts.

In a particularly advantageous embodiment of the invention, the features of the last paragraph are incorporated, together with an aforementioned featurewherebythefinal drive axis lies in a plane which also includes a joint facet between the cylinder block and cylinder head, and thus there may be provided on the main casing part a single extended flat surface designed to serve as an abutment face for both the cylinder head and for the final drive covering part, thereby enabling a further reduction in machining costs. Preferably, this face may be machined parallel with a further facing ofthe main casing part which may include the crankshaft axis, and to which abuts thecombined crankcase and transmission closing part, and perpendicular to the cylinder axes.

The cylinder head design may include ports which emerge on the side face which is adjacent to the transmission parts, and in order then to permita compact juxtaposition of cylinder head and final drive components, particularly in an embodiment which may incorporate the features of the two preceeding paragraphs, such ports may be provided having a steep downdraught angle relative to the cylinder axes, such that, where these are, for example, inlet ports, there may be provided extended induction tracts which run in a substantially straight line, passing immediately above the final drive parts, but which may yet, due to the general configuration ofthe power unit, be of an updraught nature, and such that their extremities may lie at a very low level outboard ofthefinal drive parts.Such provisions are particularly advantageous in the case of an embodiment designed to be installed in the rear of a vehicle, and wherein the crankshaft is located in front of the final drive axis, and such that the extremities of the induction system, being low, may be accommodated beneath the boot floor of the vehicle, thus permitting the use of tracts which are long, and thereby favourable to the enhancement of engine output atthe lower operating speeds, butwhich are free of sharp bends which might inhibit gas flow and hence power at higher speeds, and which meanwhile cause a minimum of intrusion into areas oftheveh- icle which may be required to accommodate luggage or other components. Also, the inlet ports are thus provided at a favourable angle of approach to the cylinders.

In an embodiment wherein the engine incorporates a fuel injection system, the injectors may be positioned on the upper side of the induction tracts, at a point approximately directly above the final drive parts, and so as to be aimed in a favourable manner almost directly down the inlet ports onto the back of the inlet valves, but so as also to be located in a particularly accessible position. Fuel injection may be a particularly desirable feature of a power unit ofthe nature herein intended, both in ordertofurther improve overall operating efficiency, and also to avoid problems such as fuel puddling which might otherwise be caused by the use of an updraught sec- tion in the induction tract, and the aforementioned features provide a particularly favourable installation.

Both the cylinder head and the crankcase closing part may be retained to the main casing part by fastening devices such as long bolts, and in an embodiment wherein the cylinder bore and the main bearing diameter and suitably related, the fasteners for the two components may share the same axes, and further, there may then be provided singular long fasteners passing right through the main casing part and serving to retain both the cylinder head and the crankcase closing part by linking those two parts together, and such fasteners may be provided such that they are threaded into the cylinder head from its underside, and such that they may be operated from outside ofthe crankcase closing part.The power unit configuration proposed herein particularlyfacilitates such provisions, which may be especially favourable in embodiments wherein considerations related to the design ofthe cylinder head dictate that a component such as a camshaft should be positioned such that it masks access to the cylinder head fasteners, as may occur particularly in cylinder heads ofthe four valve per cylinder variety with pent roof combustion chambers. Such a fastening arrangement may also be favourable to certain installations ofthe power unit in a vehicie.

The crankcase closing part may be designed such that the chamber in which the crankshaft operates is separated from a further lower chamber, in which may be contained lubricating oil, and the main crankchamber may thus be designed such that its internal surfaces are smooth and shaped so as to minimise crankcasewindage losses.Furthermore, ports may be provided linking the two chambers, th rough which lubricant may return to the lower chamber, and these ports may be shaped so as to effect a natural continuation of the path of flow of lubricant within the main chamber, and hence so asto minimise restriction to the return flow, particularly in the case where the crankshaft rotates in a direction such that the crankpin moves downwards through the main proportion ofthe crankchamber in the crankcase closing part.

The transmission system may include, in addition to the aforementioned parts on the final drive axis, further parts such as might constitute a gearbox, and ofwhich the principal functional elements are arranged along axes which may be mutually parallel and which may be called the gearbox axes, which parts may be accommodated within the power unit arrangement in a manner whereby particularly efficient use is made of an availabie space, and such that the parts are contained within a section ofthe aformentioned transmission housings which lies more adjacent to the crankcase and which may extend beneath the central and outer cylinders, and such thatthe gearbox axes are arranged substantially parallel to the final drive axis, and hence also to the crankshaft axis, and such that one gearbox axis, which may be called the gearbox mainshaft axis, may be located approximately midway between the final drive axis and the crankshaft axis, all three of which axes may lie on approximatelythe same level, while a second gearbox axis may be located substantially directly below the mainshaft axis. The furthertransmission parts may thus be accommodated entirely within the power unit profile which is determined by the arran gement of the engine and final drive parts, even though this profile is itself very compact.

In orderto effect driving communication between the crankshaft and gearbox mainshaft axes, which latter may also be called the gearbox input axis, there is provided a primary drive medium which may be Jocated to one end of the power unit, and which may take the form of the pair of gears, while there may also be provided adjacent thereto a clutch, preferably centred on the gearbox mainshaft axis, and thus arranged so as to be able to effect driving connection between the primary drive medium and the gearbox.

Arranged thus, the periphery ofthe clutch parts need not, as it might were the clutch centred on the crankshaft axis, extend outside the profile ofthe power unit as determined by aformentioned components and as viewed in a direction along the crankshaft axis, not even in the regions where the said profile is determined solely by the cross-section of the crankcase structure, and also, as a result of this arrangement, parts which may be provided within the transmission system and associated with gearchanging, such as, for example, synchronisers, are not subject to the inertia of the primary drive parts.The combina tionofaclutch positioned thus and a primary drive consisting of only two gears is particularly favourable, the drive being efficient since only a single gear meshing point is involved, and more so since the gears may necessarily be of a large diameter and the loads at the meshing point thus correspondingly low, and while the inertia value of such gears may be considerable, the preferred clutch position eliminates any detrimental effectthereof. Further, since the gears are in permanent driving communicationwith the crankshaft, they may contribute a proportion of the flywheel effect required by the engine, and thus allowthe use of a main flywheel of reduced mass, and also, since the flywheel effect is thus accumulated from contra rotating elements, a smoother idling performance may be expected ofthe engine.While the dynamic advantages associated with the combination of a two gear primary drive and a clutch located on the gearbox input axis are applicableto any power unit requiring a primary drive medium, such features are only feasible in a power unit arrangement such as that provided by the present invention, and where the gearbox input axis is at a sufficiently high level to enable the clutch to be provided with adequate clearance above the road surface.

In orderthatthe profile of the power unit, as viewed in a direction along the crankshaft axis, should not be enlarged by requisiteauxiliarycompo- nents such as an alternator, a starter motor and a distributor, such components may be provided located to the ends of the power unit and extending outwards.In an embodiment wherein the clutch is positioned on the gearbox input axis, and physically outboard ofthe primary drive parts, and is of the dry plate variety, the alternator may be driven by means of a friction wheel engaging with the outer periphery ofthe drum containing the clutch parts,whilethe starter motor may be provided able to mesh with a gear affixed to the said drum, and these auxiliary components may then be arranged so asto lie one above the other, and extending outwards from an area approximately in line with the end of the crankcase, while the distributor may be driven from one end ofthe engine camshaft. In an embodiment wherein the engine is liquid cooled, a coolant pump may be provided driven from a point within the camshaft driving mechanism, and the pump may be located at a low level relative to the cylinders and cylinder head, such that coolant may flow advantageously in a basically upward direction through the engine. An additional advantage oftheforegoing features is thatthere is thus no need for any external belt drive, and further, no need forthe crankshaftto emerge from the end covers of the power unit, and hence no need for oil sealing devices contacting the crankshaft.

Such sealing means may be provided on the gearbox input axis to protectthe dry plate clutch, and provided the engine and transmission parts may share a common lubricant, the only other seals required are at the points where the final drive output members emerge from the transmission housings.

The power loss associated with oil sealing may thus be minimised.

In viewoffurtheraims such as that concerning a small number of loaded gear meshing points, a preferable embodiment ofthe invention includes a transmission system such as that which is described in the text subsequent hereto. Whilst being based upon gearboxandfinal driveaxeswhich maybe arranged in the manner described in a preceeding paragraph, the transmission system may also be used advantageously independently of the power unit described herein, for example in integrated power units of other configurations or in transaxle devices.

According to this aspect of the invention, there is provided a rotarytransmission system, designed to operate in a motor vehicle as a combined gearbox and final drive mechanism affording a series of overall speed ratios, and incorporating an input shaft, a layshaft and a final drive output component, ail rotateable about discrete axes which may all be arranged substantially parallel with the virtual axles ofthe vehicle, and incorporating also a set of gears arranged such that at least two gear pairs of differing ratio are alternatively engageable with each pair having a driving gear coaxial with the input shaft and a driven gear coaxial with the final drive output component, which gears may collectively be termed thefinal drive gears, while at leastonefurtherpairof gears is engageable to provide drive from the input shafttothe layshaft, and at least one pairofgears is engageable to provide drive back fro the layshaftto a partcoaxialwiththeinputshaft Atransmission system having these features can provide at leasttwo speed ratios selectable such that in either, the drive path through the system is direct along the axis ofthe input shaft to a final drive driving gear, and thence via the corresponding driven gear to the final drive output component, such a drive path thus including only a single gear meshing point between the input shaft and the final drive output component, these speed ratios being termed the direct ratios and each being equivalent to a 'top' gear in the case of a conventional three shaft gearbox operating in conjunction with a final drive gear pair, while a number of further speed ratios, which may be termed the indirect ratios, may be provided by way of the layshaft, according to any known practice.

In an arrangement which represents a reversal of the practice which is more usual in layshaftgearboxes in motor cars, a number of indirect gear pairs are provided alternatively engageable between the input shaft and the layshaft, whilst there is also provided on the layshaft a constant mesh output pinion, engageablewith an output gear.

In a particularlyfavourable embodiment, the output gear referred to in the preceeding paragraph is one of the final drive driving gears.

The features of thins embodiment, which are especially suited to the power unit arrangement disclosed herein, orto other applications where the layshaft centre need not lie in a line between the centres ofthe input shaft and the final drive output component, can provide a num ber of indirect ratios equal to the number of indirect gear pairs, each such thatwhen selected the drive path through thetransmission system is from the input shaft, via the engaged indirect gear pairto the layshaft, and thence byway of a train of three gears to the final drive output component, the central element of the train being the final drive driving gear in this case operating only as an idler gear between the constant mesh output pinion and the corresponding final drive driven gear, such a train providing an output path of potentially favourable efficiency. Furthermore, the total number of gears in such an embodiment can be less than in an equivalent transmission system of a more usual design, and the overall length, weight and cost may thereby all be favourably influenced.

In an arrangement which affords a reverse speed ratio n a particularly advantageous manner, there is provided on the layshaft a further pinion, which may be known as the reverse pinion, and which is en- gageable directly with a final drive driven gear.

This feature, which again is suited to the power unitarrangementdisclosed herein, orto otherapplications wherein the shafts can be arranged such that the centres ofthe input shaft, the layshaft and the final drive output component form the vertices of a triangle, can provide a reverse speed ratio wherein the drive path through the transmission system is from the input shaftto the layshaft by way of a pairof gears which may be an indirect gear pair as aforementioned, and thence directly to the final drive output component by way of the reverse pinion and thefinal drive driven gear.The feature thereby enables a reverse speed ratio to be provided without the need for an additional shaft axis and thus without increasing the envelope of the transmission system, and with only one additional gear being necessary. In embodiments having a numberofindirectgear pairs, it is possible, if required, to provide an equal number of reverse speed ratios.

Preferably all the gear pairs in thetransmission system should be in continuous meshing engagement, and in order to effect selection of the various speed ratios, there may be provided devices which can connect appropriate gears with their supporting shafts, which devices may be synchronised dog clutches of any known type.

In an embodiment in which the transmission system is of the constant mesh type described above, a number of other preferable features may be combined in a manner which permits further advantage, and thus with the shaft centres being in a triangular arrangement as aforementioned,there are provided the following: an input shaft which extends the full length of the complete transmission system, and which may then be known as the mainshaft; two final drive gear pairs each having a driven member permanently affixed to the final drive output component and a driving gear which is a discrete component supported by the said mainshaft; a number of indirect gear pairs each having one member permanently affixed to either the mainshaft or the layshaft and the mating gear a discrete component supported by the other ofthe two said shafts; a connecting device as aforesaid adjacent to each ofthe final drive driving gears and to each indirect gearwhich is a discrete component; a mechanism to ensure that only one such device can be connected at a given time; a constant mesh output pinion engaging with the larger ofthe two final drive driving gears; a reverse pinion engaging with the largerofthetwofinal drive driven gears; and a device by means of which the layshaft can be connected eitherwith the constant mesh output pinion with the reverse pinion, which device may be an unsynchronised dog clutch, and in such an arrangementthe shaft centre distances and the relevant gear diameters being chosen such thatthe constant mesh output pinion cannot contactthe final drive driven gear with which it is entrained, and such that similarlythe reverse pinion cannot contactthe final drive driving gear with which it is entrained.

Atransmission system having these features may operate as follows: for all forward speed ratios, the constant mesh output pinion is connected with the layshaft; for each indirect speed ratio,the connecting device adjacent to the appropriate indirect gear pair is engaged, such that drive may pass from the mainshaftto the layshaft and hence to the final drive output component byway of the constant mesh output pinion and the final drive gear pair entrained therewith, with the driving gear operating as an idler; for each direct speed ratio, the connecting device adjacent to the appropriate final drive driving gear is engaged, such that drive may pass directlyfrom the mainshaftto the final drive output component; for a reverse speed ratio an indirect gear pair is engaged as aforementioned, and the layshaft is disconnected from the constant mesh output pinion and instead connected to the reverse pinion, such that drive may pass from the mainshaftto the layshaft and thence directly and in the required sense for a reverse speed ratio, to the final drive output component. The transmission system thus does not require a gearbox output shaft as such, nor does it require a spigot arrangement such as is common in layshaft gearboxes, and the design thereby facilitates the provison of a favourable mainshaft bearing arrangement.

Preferablythe reverse pinion is provided with a static supportive stub shaft, coaxial with the layshaft, in order to avoid possible large speed differentials whiletheforward gears are engaged.

In a preferred designforafivespeed and reverse constant mesh transmission, the combination of features just described is embodied, and in orderto provide fourth and fifth speeds as direct ratios, there are provided two only final drive gear pairs of appropriate diameters,togetherwith three indirect gear pairs for the first, second and third speeds, of which thatforfirst speed is utilised in the reverse geartrain.

Whilst providing the two direct upper speed ratios and also thethree lower speed ratios having an advantageous drive path, as well as providing a reverse speed ratio, such a transmission system yet contains, otherthan the parts of the final drive axis, only ten gearwheels in total, and these on onlytwo shaft axes, and may thus be particularly compact and light, as well as of low cost.Furthermore, the arrangement allows that synchronisers for the lower ratios may be provided in positions where the referred inertia of the clutch plate and associated items, as sensed by the synchronisers, is less than in equivalent transmissions of a more usual design, and hence such synchronisers may be comparatively more efficient To yetfurther advantagethe arrangement, particularly when used in conjunction with a primary drive means, lends itself to a feature whereby the said ten gearwheels are not all of different sizes, even in a transmission system which provides a most favourably spaced series of speed ratios, and thus, concerning the indirect gear pairs for second and third speeds, the mainshaft gear of the one pair may have the same diameter as the layshaft gear of the other pair, and vice versa, and meanwhile the final drive driving gearforfourth speed may havethe larger of these two diameters, and also the indirect gear pair for first speed may bear a similar reciprocal relationship to the gear pair which comprises the final drive driving gearforfifth speed and the constant mesh output pinion, and the reverse pinion may also have the smaller of these two diameters, the same as the constant mesh output pinion. Thus the set of ten gears may include gears of only four different diameters.

Moreover, in an embodiment in which the further transmission components such as engagement devices are suitably arranged, those gear wheels which are of equal diameter can be made similar in all other respects, and thus the set often gears forthe five speed and reverse transmission may be comprised of only four different components, two of which being used twice over and the other two three times over. Afurther reduction in manufacturing cost may thereby result.

In a particular example wherein the speed ratios are chosen to suit a sports car and advantageously such that the series of vehicle road speeds corresponding to a given engine speed approximately form an arithmetic progression, the set often gears is made up only of gearwheels having 27 and 32 teeth, mating with pin ions having 23 and 17 teeth respectively, with, in the final drive positions, the gearwheels mating with driven gears having 77 and 73 teeth respectively, and meanwhile a primary drive is incorporated having a ration appropriate according to the road wheel size to providethe required overall speed ratios.

A gear selector mechanism for operating the dog clutches may be located in the region beneath the crankshaft and adjacent to the mainshaft and layshaft, such that in vehicle installations where the crankshaft lies between the gearchange lever and the transmission parts, a selector linkage of a favourable direct nature can be arranged to pass beneath the crankshaft.

In an intended application where a transmission system such as that described above is incorporated in parallel with a transverse engine into an integrated power unit, which may be configured in the manner described herein, and where there maythen be provided a primary drive from the engine to the transmission which consists of only a single pairof gears, again as described elsewhere herein, the engine and transmission parts may be positioned such that when installed in a vehicle, the main power unit structure, and also the final drive output component, which may be a differential, together with the final drive gear pairs may all be disposed substantially symmetrically aboutthe longitudinal centre line of the vehicle, and such that there may be provided equal length final drive output shafts to an adjacent pair of driven road wheels, and thus may be obtained the advantages of such symmetry while having a transmission system in which fourth and fifth speeds, for example, are provided such that there are only tow loaded gear meshing points in total between the crankshaft and the driven road wheels.

The indirect gear pairs can then all be located to one side ofthe final drive parts, and a particularly favourable installation results, for example, when the transmission is of the five speed variety described above and the engine has four cylinders, whereupon the length betweenthefinal drive parts, being located adjacent to the central cylinders, and one end of the cylinder block may be just sufficient to conveniently contain the three indirect gear pairs and associated components, and meanwhile the primary drive parts can be located at this same end ofthe power unit.

Whilst a ny power u nit of this sym metrical nature is well suited to having directly attached a suspension system, including such a system ofthetypewherein the final drive output shafts constitute part ofthe linkage, the power unit configuration according to the present invention may offer an additional advantage in this context in that, with the cylinder block being inclined above the transmission, the upper portions ofthe end faces ofthe said block are then more nearly directly above the final drive shafts.

According to a further aspect of the invention, there is provided a suspension system designed to operate on a non-steered driving wheel of a vehicle, and designed to be mounted directly to an adjacent driving unit such as the transverse integrated power unit described herein, in which system a universally jointed driving shaft acts also as a lower transverse memberofa linkage,thelinkagefurthercomprising an uppertransverse arm and a wheel carrying member, the driving shaft joints connecting respectively with an axially supported output shaft of the driving unitandawheel hubspindlewhichis supported in bearings in the wheel carrying member, while the uppertransverse arm is a rigid member and has its ends connected respectively with the top of the wheel carrying member and the supporting structure ofthe driving unit by means of pivots whose axes both lie approximately parallel to the direction of motion of the vehicle, the linkage thus being constrained to a prescribed articulation only.

Preferably, the uppertransverse arm has an effective length less than that of the driving shaft.

Whilst providing a more favourable geometry of wheel movement, this feature is particularly suited to a matching ofthe suspension system with a power unit of the configuration described herein, and where the end faces of the cylinder block lie outboard ofthe connections to the output driving members, and furthermore the feature is advantageous to the provision ofan arm of suitable rigidity.

The axes ofthe pivots on the uppertransverse arm may be slightly angled to provide anti-squat effect, etc., if desired.

Motion ofthesuspension linkage maybe controlled, for example, by a coil spring, concentric with a telescopic damper connected between a lower partofthewheel carrying memberandthe inner fulcrum ofthe upper transverse arm.

Such a suspension system, whilst able to locate the wheel in all directions, providing a favourable geometry and being particularly suited to the present application, is also particularly simple, of low weight and may be constructed at low cost, these advantages being partly attributable to the utilisation ofthe driving shaft to perform a second function, and meanwhile the need for devices which allowthe driving shaft to change its effective length is eliminated. Also, the adjunction of material required to mount such a suspension to the power unit described herein is minimal.

Byso mounting the entiresuspension system directly to the power unit, favourably accurate control of wheel articulation can be achieved, and meanwhile there can be made economies in the structural design ofthevehicle. However, it is desirable thatthe entire assemblage of power unit and suspension should be flexibly mounted to the vehicle structure in orderto provide isolation from both power unit and road induced vibrations.

According to a final aspect ofthe invention, there is provided a power unit mounting system designed particularly to suit a sports car having a transverse power unit such as that described herein installed adjacent to the rear wheels, and applicable also to other vehicles wherein the spatial requirements of the system are acceptable, within which system there is provided attached to the front face ofthe powerunitasubstantial beam,which may be of hollow box section and which extends forwards, for example within the space between the seats of the vehicle commonly called the transmission tunnel, and to a point which may be close to a front bulkhead of the passenger compartment, at which point is provided a front flexible mounting connecting the beam with the vehicle structure, while two further such flexible mountings are provided close to each rear wheel, connecting the power unit casings to points on the vehicle structure which may be adjacent to a rear bulkhead.

Thus the longitudinal separation ofthefront mounting may be considerable, and since this distance is effective as a lever arm in reacting driving torque, mountings may thus be provided which are comparatively more flexible, particularly in a verticai direction, as may be advantageous in providing more effective isolation ofvibrations.

In arrangements where the rearsuspension is attached directly to the power unit, the mounting flexibilities may advantageously be chosen in accordancewiththe masses involved suchthatthe power unit mass can act as a dynamicabsorberof road induced vibrations.

Meanwhile the beam may itself be utilised for example as afuel tank, which may thus be located in the centre ofthe vehicle, in a position of minimum vulnerability in the event of a collision, and also where changes in fuel load have the least effect on vehicle weight distribution.

Furthermore,the beam may also carry the pivot for a gearchange lever, which pivot may thus be rigidly linked to the power unit structure, thereby facilitating the provision of a favourable gearchange linkage.

The combination of this feature and a power unit arranged as disclosed herein and having a selector mechanism positioned as aforementioned is particularly advantageous to gearchanging, since a rigid connecting link can be provided passing beneath the crankshaft in a direct line from the gearchange lever to the selector mechanism.

A reversed form of the mounting system may be used in front drive vehicles.

According to the invention, there is also provided a power unit, rotarytransmission system, a suspension system and a mounting system, oray combination thereof, comprising any novel feature or concept or novel combination features or concepts disclosed herein.

The drawings herewith show, byway ofexample only, a power unit and also a suspension and mounting arrangement in accordance with the invention, the power unithaving four cylinders and a five speed and reverse transmission, and being designed to be incorporated transversely adjacent to the rearwheels of a vehicle, with its crankshaft ahead ofthe axle line. Drawings are included which show, again by way of example only, the manner in which two slightly differing versions might be installed in rear drive vehicles and also how modified versions of the power unit might be used in front drive vehicles.

In the following, the terms cross section and end view are used to referto views in the direction of the crankshaft axis, and hence, in the drawings: Figure 1shows a cross section of the power unit through an outer cylinder and the transmission parts adjacent thereto.

Figure2 shows a view ofthe cylinder head and final drive housing splitface of the power unit with the cylinder head and all the casing parts removed otherthanthe main casing part, the view being in the direction of the cylinder axes.

Figure 3 is an end view of the power unit showing the arrangement of auxiliary components.

Figure 4shows the transmission system with, for ease of understanding, the final drive axis appearing as if in the same plane as the mainshaft and layshaft axes.

Figure Sshows schematically the transmission system as in figure 4.

Figure 6shows a cross section of the power unit taken between the central cylinders and particularly shows the arrangement ofthe fourth speed final drive gears, as well as the cylinder head bolting arrangement.

Figure 7shows in another cross section the arrangement ofthe fifth speed final drive gears.

Figure 8shows the power unit of figures 1 to 7 installed adjacent to the rear wheels of a sports car, and equipped with a cylinder head with twin overhead camshafts.

Figure 9 shows the power unit of figures 1 to 7 installed adjacentto the rear wheels of a saloon car, and equipped with an alternative cylinder head with a single overhead camshaft.

Figure 10 shows installed adjacent to the front wheels of a saloon car, a power unitsimilartothatin figures 1 to 7 except four having either a reversed direction of engine rotation or an alternative primary drive design.

Figure 11 shows installed adjacentto the front wheels of a saloon car, a powerunitsimilartothatin figures 1 to 7 exceptfor having a different cylinder head with downdraughtinletports.

Figure 12 shows the rear suspension attached to the power unit of figures 1 to 7, as viewed from the rear a vehicle as in figures 8 or9.

Figure 13 shows a plan view of the rear suspension arrangementoffigure 12.

Figure 14 shows a side elevation of the mounting arrangement associated with the power unit and suspension assembly of figures 12 and 13.

Figure 15shows a plan view of the mounting arrangementoffigure 14.

As best seen from figure 1 and from figure 2,the power unit comprises an internal combustion engine 1 and a rotary transmission system 2, and provides output drive along a final drive axis 3, the transmission having also a mainshaftaxis4and a layshaft axis 5, and the engine having its crankshaft axis 6 ahead of and parallel to all ofthese transmission axes, and its cylinders 7 sloping steeply backwards over the transmission system 2.The power unit structure is based upon a main casing part 8, which includes cylinder, crankcase and main transmission housing in an integral unit. Acrankcase and transmission closing part 9 adjoins thereto in a plane which includes the crankshaft axis 6 and which is normal to the axes ofthe cylinders 7,whilea cylinder head 10 and a final drive covering part 11 also adjoin the main casing part 8, both abutting to the same facing 12, with which also coincides the final drive axis 3, this facing also being normal to the axes of the cylinders 7. The engine 1 has, rotating about axis 6 in the direction indicated by arrow 13, a crankshaft 14, driven by connecting rods 15from reciprocating pistons 16.Main bearings 17 are provided half in the main casing part 8 and half in the crankcaseandtransmission closing parts.

Similariy bearings 18for a differential unit 19, shown in figure 2, are provided half in the main casing part 8 and half in the final drive covering part 11. The cylinder head 10 has inlet ports 20 approaching the cylinders 7 at a steep downdraught angle, and which are fed from long induction tracts 21, which are free of sharp bends, and which are formed, together with a plenum chamber 22 into a manifold 23, which lies at a sufficiently low level to be accommodated beneath the boot floor of a vehicle.

Fuel injectors 24 are provided in an accessible position,and aimed directlyatthe backsofinlet valves 25, which are operated by camshaft 26. The arrangement ofthe exhaust valves and ports is not shown, it being intended that alternative versions of the engine should have either, for maximum performance, a cylinder head with twin camshafts and four valves per cylinder, orfor minimum height and lower cost, a cylinder head with a single camshaft and two valves percylinder.

The arrangement of bolts 27 forthe cylinder head 10 and the crankcase and transmission closing part9 is shown in figure 6, from which it can be seen that the camshaft 26 would otherwise mask access to the bolts and prevent removal ofthe cylinder head 10 and associated parts as a complete assembly.

Additional subsidiary attachment bolts (not shown) would be provided for both the crankcase and transmission closing part9 and the cylinder head 10, to allow either to be removed without the other being disturbed.

Meanwhilethe crankcase and transmission closing part 9, as seen in figures 1 or 6, is split into two separate chambers, the upper crankchamber 28 having a smooth internal form to reducewindage, while the lower chamber 29 is used to contain lubricating oil, ports 30 being provided to allow oil to return from the crankchamber 28 to the lower chamber29, and these are shaped so asto effecta natural continuation ofthe path offlowwithin crankchamber 28. The lubricating oil, which is used for both engine and transmission, is also contained in the bottom of the main casing part 8 and the final drive covering part 11. It is circulated by a pump (not shown) concentric with the crankshaft 14, in a circuit which includes the main oil gallery 31.Also concerning lubrication, in figure 2 is shown a passage 32 by means of which oil may drain from the cylinder head 10 into the transmission housing part ofthe main casing part 8.

Figure 2 also shows, attached to the differential unit 19 in an arrangement symmetrical with respect to the cylinders 7, the two final drive driven gears 33 and 34, and, atthe end ofthe engine the primary drive gears 35 and 36 by means ofwhich drive is transferred from the crankshaft axis 6 to the mainshaft axis 4, and also the clutch unit 37, centred on the mainshaft axis 4, and having on the periphery of its drum 38, startergearteeth 39. The end covers of the power unit are not shown in this view. That atthe primary drive end contains an oil seal acting on the surface 40 between the primary drive driven gear 36 and the clutch unit 37, which is of the dry plate type.

As can be seen from figure 3, auxiliary components are arranged atthe end ofthe power unitwhere resides the clutch unit 37, there being an aiternator41 driven from the drum 38 ofthe clutch unit 37 by means of a friction wheel (not shown), and also a starter motor 42 engageable with the teeth 39.

Integral with the end cover 43 is a housing 44 containing a pivot pin and bearings for a rear suspension upper link, this pivot lying above the drum 38 ofthe clutch unit37. The distributor45 is driven directlyfrom the end of the camshaft 26.

Figures 4and 5 reveal the arrangement ofthe components ofthetransmission system 2 along axes 3,4 and 5, figure 5 being a schematic representation only and figure 4 also being a simplified representation,with in both figures the axes 3,4 and 5 appearing as if in a single plane, whereas theirtrue relationship is as shown in figures 1,6 and 7. Besides the differential unit 19 and the gears33 and 34 attached thereto, all centred on the final drive axis 3, the transmission can also be seen to have on the appropriate axes 4 and 5 respectively, a mainshaft 46 and a layshaft47. The mainshaft46 is supported by bearings 48,49 and 50, while the layshaft 47 is supported by bearings 51 and 52.At its input end, the mainshaft 46 carries on a bearing 53 the assembly of the primary drive driven gear36 andthe clutch unit 37, and may be driven therefrom through the spline 54, the clutch unit 37 being constructed according to conventional artand having adriven plate55which may be clamped between the drum 38 and the pressure plate 56 by means of the diaphragm spring 57. At its other end the mainshaft46 carries on bearing 58 and 59 respectively, the final drive driving gears 60 and 61, and is connectable to either by means ofthe sliding dog clutch 62.The latter is shown for simplicitywithout any synchronising devices, though such would normally be provided according to a known practice, and it is controlled from the vehicle gearchange unit. The driving gears 60 and 61 are in mesh with the driven gears 33 and 34 respectively, these gear pairs when engaged by the dog clutch 62 providing the direct drive for respectively fifth and fourth speeds.

The final drive driving gear 60 is also in mesh with the constant mesh output pinion 63, which is carried on bearing 64 on the layshaft 47, and which is connectable with the layshaft47 by means of the unsynchronised sliding dog clutch 65. The dogged connection between the layshaft 47 and the pinion 63 is maintained engaged for all forward speeds, the layshaft47 then being in constant mesh with the output elements of the transmission system. In the indirect first, second and third speeds, the layshaft47 drives the differential 19 through the train of gears 63,60 and 33, with the dog clutch 62 being in its neutral position such that the gear 60 can act as an idler.To provide inputdrivefrom the mainshaft46to the layshaft 47 for these indirect speed ratios, the mainshaft46 carries the driving gears 66,67 and 68, while the layshaft47 carries, respectively enmeshed therewith, the driven gears 69,70 and 71. The gears 66 and 67 are fastwith the mainshaft46whilethe gear 71 is fast with the layshaft 47.The gear 68 is carried onthe mainshaft46 by bearing 72, and is connectable to the mainshaft 46 by means of the sliding dog clutch 73, in orderto providethethird speed. Similarlythe driven gears 69 and 70 are carried on the layshaft 47 by bearings 74 and 75 respectively, and either is connectable with the layshaft47 by means ofthesliding dog clutch 76, in orderto provide first or second speeds respectively.

The dog clutches 73 and 76 are shown, for simplicity, like the dog clutch 62, withouttheir synchronising devices, and similarly likewise are controlled from the vehicle gearchange lever.

The sliding dog clutch 65, which is unsynchronised, is also used forconnecting the layshaft47 with the reverse pinion 77,which is carried on bearing 78 on the stub shaft 79, co-axial with the layshaft 47. Although not apparent from figures 4 or 5 due to the distorted representation used therein, the reverse pinion 77 is actually in mesh with the final drive driven gear34, as indicated by the dotted line 80.

Figures 6and 7 showthetrue relationships ofthe gears 34,61 and 77, and 33,60 and 63 respectively, and thus it is apparent from figure 7 how the constant mesh output pinion 63 is in mesh with the final drive driving gear 60, but clearofthe corresponding driven gear33,whilefigure 6 shows howsimilarlythe reverse pinion 77, while being in mesh with the final drive driven gear 34, is clear of the corresponding driving gear61.

The pinions 63 and 77 are of equal size, a common componentwith 17teeth being used in both these positions, and the same component is also used as the first speed driving gear66. In a similarmanner,a common component with 32 teeth is used as gears 60 and 69, a common component with 27 teeth is used as gears 61,68 and 70, and a common component with 23 teeth is used as gears 67 and 71.

The set often gears on the axes 4 and 5 is thus made up from only four different components. The final drive driven gears 33 and 34 have 73 and 77 teeth respectively, and for a particular application the primary drive gears 35 and 36 have 48 and 53 teeth respectively.

In orderthatthe first speed gear 66 can be commonised with pinions 63 and 77, and also because of considerations of desirabie diameters, the gear66, as shown infigure4, has a plain bore where it locates on the mainshaft 46, and is driven therefrom by means of a splined dog coupling ring 81, the whole mainshaft assembly being clamped together by the nut 82. Figure 4 also shows howthe differential 19 has its side bevels 83 splined to the output shafts 84 which are supported by bearings 85.

Meanwhile, figures 1,6 and 7 also indicate elements of a gear selection mechanism which includes the selector rods 86 and an assembly of concentric cam drums 87.

Figures 8 to 11 exemplify installations ofthe power unit in vehicles.

In figure 8 is shown a two seater sports car in which the power unit is fitted immediately behind the seats and drives the rear wheels. The profile of the power unit is seen to be especially suited to this particular application, being of a wedge like form which corresponds with the shape ofthe recess which exists beneath and behind the sloping bulkhead 88, such that spatially efficient packaging of the vehicle elements is facilitated. As a result, the rear luggage space 89 is seen to be comparatively large for a car of this type, and also, due to the lowness ofthe power unit, a shelf 90 can additionally be provided forthe stowage of small items, which is accessible from within the passenger compartment.The seat headrests 91 could be hinged to facilitate such access, while a division 92 between the shelf 90 and the luggage space 89 couid be provided adjustable to allowthe relative sizes of the two areas to be varied as required. Meanwhile it can be seen that the power unit arrangement allows that the induction system can be accommodated with the manifold 23 beneath the bootfloor and thus not encroaching into useable luggage space. Also, the power unit, which has the twin camshaft cylinder head, is seen to be located such that its centre of gravity would liefavourably withinthevehiclewheelbase.

In figu re 9 is shown a four seater saloon carwhich is ofthe 'hatchback' type, in which the power unit, equipped with a single camshaft cylinder head for minimum height, is again fitted to drivethe rear wheels, and yet due to its lowness is accommodated beneath a rear luggage platform 93 which is little higher than that in corresponding front drive cars.

The luggage platform would be extendable by folding the rear seats, as is conventional in such vehicles, while a further advantageously invisible luggage space could be provided atthefront ofthe vehicie.

In figures 10 and 11 are shown two examples where the power unit is slightly modified form is installed to drive the front wheels of a saloon car. As shown in figure 10, the power unit is fitted in a reversed configuration with its crankshaft behind the final drive axis. In order to have the correct direction of rotation of the output drive shafts, eitherthe direction of rotation of the crankshaft would haveto be the reverse, relative to the rest of the power unit, of that indicated by arrow 13 in figure 1, orthe primary drive gears 35 and 36 would have to be replaced by a chain drive orto have an idler gear interposed.As shown in figure 11,the engine has its crankshaft ahead of the final drive axis, but, for greater convenience of installation, has a different type of cylinder head such thatthe induction manifold 23 can be of a downdraught nature. In both ofthe examples shown in figures 10 and 11,the configuration ofthe power unit can permit either an exceptionally low and aerodynamic bonnet line, or the provision of a front luggage space as aforementioned above the power unit.

In all ofthe examples shown in figures 8to 1 1,the power unit would be installed centrally within the width ofthe vehicle, and thus such that variants with, for example, six or eight cylinders in line could be similarly accommodated.

As depicted in figures 12 and 13, the rear suspension comprises an upper transverse arm 94, a wheel carrier 95 and a final drive shaft 96 which acts as a lowertransverse arm and has universal joints 97 at either end. The arm 94 has at its inner end a pivot pin 98 supported by bearings 99 in the housing 44of the power unit end cover 43, while at its outer end another pivot pin 100 carries bearings 101 held in the wheel carrier 95. The arm 94 and the wheel carrier 95 are both substantially proportioned members, whilst the bearings99 and 101 areofthetaperrollertype, such that the assemblage ofthe arm 94 and the carrier 95 is able to sustain vehicle tractive forces.

The universal joints 97 ofthe drive shaft 96 are connected, at the inner end to the differential output shaft84(seen also in figure 4, supported by bearing 85) and atthe outer end to the wheel hub spindle 102.

Articulation of the linkage is controlled bythe spring-damper unit 103 connecting between the wheel carrier 95 and an extension of the inner pivot pin 98. The suspension unit shown in figures 12 and 13 is for the side where exists on the power unitthe primary drive. On the opposite side, the suspension is similar, exceptthat a housing equivalent to 44 is formed into the opposite end cover (not shown) of the power unit.

The arrangement for mounting the power unitand rear suspension assembly into a vehicle is shown in figures 14 and 15, in which can be seen the beam 104 attached to the front ofthe power unit and having at itsforward end theflexiblefront mounting bush 105 by which it connects to the vehicle structure. Two further rear mounting bushes 106 are fitted into arms 107 formed at extensions ofthe end casings ofthe power unit. The beam 104 is of hollow box section such that a space 108 can be used as a fuel tank.

Meanwhile the beam 104 also carriesthe gearchange lever 109 which connects with the selector cam drum assembly 87 of the transmission system by means of therod110,whichrunsinatube111throughthefuel tank section 108 of the beam 104.

A power unit assembly as described above with reference to the drawings would offer numerous advantages. Whilst many of the features are individually advantageous, they are especially intended to be mutually complementary and contributory to a design in which engine, auxiliary, transmission, suspension and mounting components are all fully integrated into a particularly compact, lightweight assembly, with no sacrifice of optimum transmission or induction system efficiency, having a low centre of gravity, advantageous mouting characteristics and a favourable gearchange arrangement, and which yet offers benefits in terms of manufacturing cost. Such as assembly would facilitate the design of cars which are more compact, light and fuel efficient, particularly in the case of cars of high performance and sports cars.

Addendum Afurtheradvantage ofthesuspension system described herein concerns its application to cars of very high performance and to racing cars, wherein it is desirable to provide an undersurface to the bodyworkshaped so astocausea downward force to be applied aerodynamically to the vehicle when it is driven at high speed, thereby improving its cornering ability.

The suspension system described herein, being free of any transverse linkage below the drive shaft, would enable such an undersurface to be formed so asto be more effective, especially in embodiments where the springing medium is also located out of the airstream.

Addendum (2) The preferred positioning ofthe clutch unit, outboard oftheprimarydrivemedium,asshown infigures2 and 4, is also particularly advantageous with regard to serviceability.

Claims (58)

1. An integrated power unit incorporating a reciprocating piston internal combustion engine and atransmission system, in an arrangement where the engine, having a number of cylinders disposed in line, is designed to operate in a position with its crankshaft axis approximately parallel to an adjacent virtual axle of a motor vehicle, and with its cylinder axes contained in a plane describing an acute angle above the horizontal, such that the crankshaft axis is ata level substantiallysimilartothatofthevirtual axlewhilethe cylinder head is located approximately directly over the virtual axle, and with its cylinders disposed either side ofthevehicle longitudinal centre line in a substantially symmetrical manner, and with the transmission being accommodated in the main within casings formed beneath the cylinders such that a section which may lie beneath the central cylinders is extended furthest from the crankshaft and encompasses an axis substantially coincident with the virtual axle at the normal ride height and known as the final drive axis, the power unit being designed to be in directdriving communication with the adjacent road wheels through universallyjointed drive shafts whose inner ends are connected with output driving members of the power unit at points which may be symmetrically disposed either side of the vehicle longitudinal centre line and which lie on the final drive axis, which axis may, by virtue of the general arrangement ofthe power unit, lie in a planewhich also includes ajoint face between the cylinder block and cylinder head.

2. A power unit as claimed in claim I,having a main casing partformedsoastoincludecylinder, crankcase and main transmission housing in an integral unit.

3. Apowerunitasclaimed in claim 2, having a combined crankcase and transmission closing part which adjoins the main casing part in a plane including the crankshaft axis, wherein the engine main bearings are provided in housings diametrally split by the jointface such that semi circular portions thereof reside in each ofthetwo adjoining casing parts.

4. A power unit as claimed in claim 2 or claim 3, having a final drive covering part which adjoins the main casing part in a plane including the final drive axis, in a design whereby the resultant enclosure constitutes the aforementioned furthest extended section of the transmission housings and such that the aforementioned power unit output drive members may emerge from the sidewalls ofthe resultant enclosure, and wherein there may be provided within the resultant enclosure, parts centred on the final drive axis a ne co n nected with the power unit output drive members, such as a differential and gearing attached thereto, which parts may be supported by bearings provided in housings diametrally split bythe joint face such that semi circular portions thereof reside in each of the two adjoining casing parts.

5. Apower unit as claimed in claim 4, in which the final drive axis lies in a plane which also includes a joint face between the cylinder block and cylinder head, the main casing part having a single extended flat surface designed to serve as an abutment face for both the cylinder head and forthe final drive covering part.

6. A power unit as claimed in claim 5, in which the said extended flat surface is machined parallel with a further facing ofthe main casing part to which abuts the combined crankcase and transmission closing part, and perpendiculartothecylinderaxes.

7. A power unit as claimed in any preceding claim, in which the cylinder head has inlet ports which emerge on the sideface which is adjacent to the transmission parts, the engine then having extended induction tracts which run in a substantially straight line passing immediately above the final drive parts but which are yet, due to the general configuration of the power unit, of an updraught nature, such that their extremities lie at a very low level outboard ofthefinal drive parts.

8. A power unit incorporating a reciprocating piston internal combustion engine, in an arrangementwhere the engine, having a number of cylinders disposed in line, is designed to operate in a position with its crankshaft axis approximately parallel to an adjacent virtual axle of a motorvehicle, and with its cylinder axes contained in a plane describing an acute angle above the horizontal, such thatthe crankshaft axis is ata level substantially similarto that ofthe virtual axle while the cylinder head is located approximately directly overthe virtual axle, said cylinder head having inlet ports which emerge on the sideface which is adjacentto the virtua I axle, the eng ine then having extended induction tracts which run in a substantially straight line passing immediately above the virtual axle but which are yet, due to the general configuration ofthe power unit, of an updraught nature, such that their extremities lie at a very low level outboard ofthe virtual axle.

9. A power unit as claimed in claim 8, having a main casing partformed so as to include cylinder and crankcase housings and having a crankcase closing partwhich adjoins the main casing part in a plane including the crankshaft axis, wherein the engine main bearings are provided in housings diametrally split by the jointface such that semi circular portions thereof reside in each ofthetwo adjoining casing parts.

10. A power unit as claimed in any one of claims 7 to 9, incorporating a fuel injection system in which the injectors are positioned on the upper side ofthe induction tracts, at a point approximately directly above the virtual axle, and so asto be aimed almost directly down the inlet ports onto the back ofthe inlet valves.

11. A power unit as claimed in anyone claims3 to 7 or in claim 9 orclaim 10, having both the cylinder head and the crankcase closing part retained to the main casing part by fastening devices such as long bolts, which fastening devices for the two components share the same axes.

12. A power unit as claimed in claim 11, in which singular long fasteners pass right through the main casing part and serve to retain both the cylinder head and the crankcase closing part by linking these two partstogether.

13. A power unit as claimed in claim 12, in which the fasteners are threaded into the cylinder head from its underside.

14. A power unit as claimed in claim 13, in which the fasteners may be operated from outside of the crankcase closing part.

15. A power unit as claimed in any preceding claim, wherein the chamber in which the crankshaft operates is separated from a further lower chamber in which may be contained lubricating oil, such that the main crankchamber may be designed with its internal surfaces smooth and shaped so asto minimise crankcase windage losses.

16. Apowerunitasclaimed inclaim 15,inwhich the two said chambers are linked byportsthrough which lubricant may return to the lower chamber.

17. A power unit as claimed in claim 16, in which the said ports are shaped so as to effect a natural continuation of the path offlow of lubricant within the main chamber.

18. Apowerunitas claimed in any preceding claim, which includes parts such as might constitute a gearbox, ofwhich the principal functional elements are arranged along axes which are mutually parallel and which are known as the gearbox axes, and which are arranged substantially parallel to the final drive axis (or virtual axle) and hence also to the crankshaft axis, and in which one gearbox axis, known as the gearbox mainshaft axis, is located approximately midway between the final drive axis (or virtual axle) and the crankshaft axis, all three of which axes lie on approximately the same level.

19. A power unit as claimed in claim 18, in which a second gearbox axis is located substantially directly below the mainshaft axis.

20. A power unit as claimed in claim 18 or claim 19, in which the said parts which might constitute a gearbox are accommodated within a housing extending beneath the central and the outer cylinders on one side of the power unit.

21. A power unit as claimed in any one of claims 18 to 20, in which driving communication between the crankshaft and the gearbox mainshaft axes is effected by a primary drive medium consisting of a single pairofgears.

22. A power unit as claimed in any one of claims 18to 21, in which a clutch is provided on the gearbox mainshaft axis, able to effect driving communication between the primary drive medium and the gearbox.

23. A power unit as claimed in any preceding claim, in which auxiliary components such as an alternator, a starter motor and a distributor are located to the end ofthe power unit and extending outwards.

24. A power unit as claimed in claims 22 and 23, in which the alternator is driven by a friction wheel engaging with the outer periphery of a drum containingtheclutch parts.

25. A power unit as claimed in claim 24, in which the starter motor, able to mesh with a gear affixed to the said drum, and the alternator are arranged so as to be one above the other and extending outwards from an area approximately in line with the ends of the crankcase.

26. A power unit as claimed in any preceding claim, in which the engine is liquid cooled and the coolant pump is driven from a point within the camshaft driving mechanism.

27. A power unit as claimed in any preceding claim, in which the engine is liquid cooled and the coolant pump is located at a low level relative to the cylinders such that coolant may flow in a basically upward direction through the engine.

28. A rotary transmission system, designed to operate in a motor vehicle as a combined gearbox and final drive mechanism affording a series of overall speed ratios, and incorporating an input shaft, a layshaft and a final drive output component, all rotateable about discrete axes which may all be arranged substantially parallel with the virtual axles ofthe vehicle, and incorporating also a set of gears arranged such that at least two gear pairs of differing ratio are alternatively engageable with each pair having a driving gear coaxial with the input shaft and a driven gear coaxial with the final drive output component, which gears may collectively be termed thefinal drivegears,whiieatleastonefurtherpairof gears is engageable to provide drive back from the layshaftto a part coaxial with the input shaft.

29. A rotary transmission system as claimed in claim 28, having a number of gear pairs alternatively engageable between the inputshaftandthe layshaft, and having also on the layshaft a constant mesh output pinion, engageable with an output gear.

30. A rotarytransmission system as claimed in claim 29, in which the said output gear is one ofthe final drive driving gears.

31. A rotary transmission system as claimed in any one of claims 28 to 30, having on the layshaft axis a further pinion, known as the reverse pinion, engageable directly with a final drive driven gear.

32. A rotarytransmission system as claimed in claims 30 and 31, in which all the gear pairs are in continuous meshing engagement, and in orderto effect selection of the various speed ratios, there are provided devices which can connect appropriate gears with their supporting shafts, which devices may be synchronised dog clutches of any known type, and in which transmission system the centres ofthe input shaft, the layshaftandthefinal drive output component form the vertices of a triangle, and there are provided the following: an input shaft which extends the full length ofthe complete transmission system, and which is here known as the mainshaft; two final drive gear pairs each having a driven member permanently affixed to the final drive output component and a driving gear which is a discrete component supported by the said mainshaft; a number of indirect gear pairs each having one member permanently affixed to either the mainshaft or the layshaft and the mating gear a discrete component supported by the other of the two said shafts; a connecting device as aforesaid adjacent to each of the final drive driving gears and to each indirect gear which is a discrete component; a mechanism to ensure that only one such device can be connected at a given time; a constant mesh output pinion engaging with the larger ofthe two final drive driving gears; a reverse pinion engaging with the larger ofthe two final drive driven gears; and a device by means of which the layshaft can be connected either with the constant mesh output pinion or with the reverse pinion, which device may be an unsynchronised dog clutch, and in such an arrangement the shaft centre distance and the relevant gear diameters being chosen such thatthe constant mesh output pinion cannot contact the final drive driven gearwith which it is entrained, and such that similarly the reverse pinion cannot contact the final drive driving gear with which it is entrained.

33. A rotary transmission system as claimed in claim 31 or claim 32, in which the reverse pinion is provided with a static supportive stub shaft, co-axial with the layshaft.

34. A rotarytransmission system as claimed in claim 32 or claim 33, providing five forward speeds and reverse, and having, in order to provide fourth and fifth speeds as direct ratios, two only final drive gear pairs of appropriate diameters, togetherwith three indirect gear pairsforthe first, second andthird speeds.

35. A rotary transmission system as claimed in claim 34, in which, concerning the indirect gear pairs for second and third speeds, the mainshaft gear of the one pair may have the same diameter as the layshaft gear ofthe other pair, and vice versa.

36. A rotary transmission system as claimed in claim 34claim 35, in which thefinal drive driving gearforfourthspeed has the same diameter as the larger gear in one ofthe said indirect gear pairs.

37. A rotarytransmission system as claimed in any one of claims 34to 36, in which, concerning the indirect gearpairforfirstspeed andthe gear pair which comprises the final drive driving gearforfifth speed and the constant mesh output pinion, the mainshaft gear of the one pair has the same diameter as the layshaft gear of the other pair, and vice versa.

38. A rotary transmission system as claimed in any one of claims 31 to 37, in which the reverse pinion is ofthe same diameter asthe constant mesh output pinion.

39. A rotary transmission system as claimed in anyone of claims 35 to 38 in which anygearswhich are of equal diameters are made similar in all other respects.

40. An integrated power unit incorporating a rotary transmission system as claimed in any one of claims 28 to 39, and incorporating also a reciprocating piston internal combusion engine in an arrangement where the engine has its crankshaft axis parallel to the axis of the final drive output component.

41. A power unit as claimed in claim 40, designed to operate in a vehicle in a position with its crankshaft axis ata level substantiallysimilartothatofthefinal drive output component, and with said crankshaft axis between the final drive output component and the vehicle gearchange lever, in which the input shaft andthe iayshaftlie in a planewhich issubstantially vertical and which lies between the crankshaft axis and the final drive output component, in which power unit a gear selector mechanism is located beneath the crankshaft and adjacent to the input shaft and the layshaft.

42. A power unit as claimed in claim 40 or claim 41, in which driving communication between the crankshaft and the gearbox input axes is effected by a primary drive medium consisting of a single pair of gears.

43. A power unit as claimed in any one of claims 40 to 42, which is designed to operate in a vehicle with its cylinders disposed either side of the vehicle longitudinal centre line in a substantially symmetrical manner, and with its transmission system arranged such that the final drive output component,togetherwith the final drive gear pairs, are similarly disposed substantially symmetrically aboutthe said longitudinal centre line, such that driving communication between the final drive output component and an adjacent pair of road wheels may be effected by means of a pair of universallyjointed drive shafts which are of equal lengths and whose inner ends are connected with the output driving members ofthe power unit at points which are also disposed substantially symmetrically about the said longitudinal centre line.

44. A power unit as claimed in claim 43, in which the engine has four cylinders in a transverse line, and in which the transmission system accords with any one of claims 34to 39, in which the three said indirect gear pairs are contained within a space to one side of the final drive parts, but which does not project beyond the end of the cyli nder bl ock.

45. A power unit which accords with any one of claims 1 to 27, and also with any one of claims 40to 44.

46. A power unit substantially as described herein with reference to figures 1 to 9 ofthe accompanying drawings.

47. A power unit as claimed in claim 46, except in regard of either the direction of rotation of the crankshaft orthe arrangements ofthe primary drive mechanism,which may be used as indicated in figure 10 of the accompanying drawings.

48. A power unit as claimed in claim 46, except in regard ofthe cylinder head and inlet manifold arrangements, which may be used as indicated in figure 11 ofthe accompanying drawings.

49. A suspension system designed to operate on a non-steered driving wheel of a vehicle, and designed to be mounted directly to an adjacent driving unit in which system a universally jointed driving shaft acts also as a lower transverse member of a linkage, the linkage further comprising an upper transverse arm and a wheel carrying member,the driving shaft joints connecting respectively with an axially supported output shaft of the driving unit and a wheel hub spindle which is supported in bearings in the wheel carrying member, while the upper transverse arm is a rigid member and has its ends connected respectively with the top of the wheel carrying member and the supporting structure of the driving unit by means of pivots whose axes both lie approximately parallel to the direction of motion of the vehicle, the linkage thus being constrained to a prescribed articulation only.

50. Avehicle drive unit which includes a power unit in accordance with any one of claims 1 to 27 or any one of claims 40 to 48, having attached thereto for each adjacent driving wheel a suspension system as claimed in claim 49.

51. Avehicle drive unit including a power unit and suspension systems attached thereto substantially as described herein with reference to figures 1 to 9 and figures 1 2 and 13 of the accompnaying drawings.

52. A power unit mounting system designed to suitacarhaving atransverspowerunitinstalled adjacent to the rear wheels, in which there is attached to the front face of the power unit a substantial beam which extends forwards within the space between the seats of the vehicie commonly called the transmission tunnel, and to a point close to afront bulkhead of the passenger compartment, at which point a frontflexibie mounting connects the beam with the vehicle structure, while two further such flexible mountings close to each rear wheel connect the power unit casings to points on the vehicle structure adjacent to a rear bulkhead.

53. A power unit mounting system designed to suit a car having a transverse power unit installed adjacent to the front wheels, in which there is attached to the rearface of the power unita substantial beam which extends rearwards within the space between the seats of the vehicle commonly called the transmission tunel, and to a point close to a rear bulkhead of the passenger compartment, at which point a rearflexible mounting connects the beam with the vehicle structure, while two further such flexible mountings close to each frontwheel connect the power unit casings to points on the vehicle structure adjacent to a front bulkhead.

54. A power unit mounting system ad claimed in claim 52 or claim 53, in which the said beam is of hollow box section, with the internal cavity being utilised as a fuel storage tank.

55. A power unit mounting system as claimed in any one of claims 52 to 54 in which the said beam carries the pivotfor a gearchange lever.

56. Apowerunitasclaimed in any one of claims 1 to 27 or any one of claims 40 to 48, which for mounting to the vehicle, incorporates a mounting system in accordance with any one of claims 52 to 55.

57. Avehicle drive unit as claimed in claim 50 or claim 51,whichformountingtothevehicle, incorporates a mounting system in accordance with any one of claims 52 to 55.

58. A vehicle drive unit and mounting system substantially as described herein with reference to figures 1 to9andfigures 12to 15 ofthe accompanying drawings.