Internal combustion engine

An internal combustion engine whose engine unit support, comprising such sound-generating parts as cylinders, cylinder head, piston rods, crankshaft bearings, crankshaft, is provided with a bracket of at least two arms at least at its output end. This bracket is attached to the bearing seats of the crankshaft and is provided with at least one sound-insulating element at each end of its arms for connecting said engine unit support to the crankcase. This will reduce any relative movements between the crankshaft and the crankcase in a simple manner.

BACKGROUND OF THE INVENTION 
The present invention relates to an internal combustion engine whose engine 
unit support, comprising such sound-generating parts as cylinders, 
cylinder head, pistons, piston rods, crankshaft bearings, crankshaft, is 
attached to the crankcase by means of several sound-insulating and 
force-transmitting elements insulating the crankcase against 
structure-borne sound. These elements are of substantially 
hollow-cylindrical shape and are located outside of the oil-wetted area in 
the crankcase, with their axes being parallel to the axis of the 
crankshaft. 
DESCRIPTION OF THE PRIOR ART 
German laid-open print No. 26 12 182 contains a description of an internal 
combustion engine whose engine unit support with its sound-generating 
parts is separated from the crankcase by a flexible element located 
between the upper edge of the upwardly extended crankcase and a flange 
running around the engine unit support. In this known type of design, the 
flexible element will both insulate against structure-borne sound and 
serve as a sealing protecting the crankcase from the loss of oil at its 
upper edge. Although this arrangement will efficiently prevent the 
transmission of structure-borne sound from the engine unit support to the 
crankcase, it has two disadvantages: the combined insulating/sealing 
element will permit comparatively strong relative movements between 
crankshaft and crankcase, and the useful life of the flexible element is 
shortened by its being in contact with hot lubricating oil from the 
crankcase interior. 
Another variant of an internal combustion engine is described in German 
laid-open No. 29 20 081, in which the sound-insulating elements for 
holding the engine unit support in the crankcase are fastened both to the 
crankcase wall so as to be accessible from outside and to the walls of the 
main bearings of the engine unit support. Although this design will 
slightly reduce the relative movements between crankshaft and crankcase, 
the flexible sound-insulating elements are subject to an even greater wear 
due to their exposure to the hot motor oil. 
A similar type of combustion engine is covered by British Pat. No. 1 137 
693, which does not have an engine unit support held in the crankcase by 
means of sound-insulating elements, but whose crankshaft bearings are 
elastically supported in the crankcase in order to reduce the transmission 
of structure-borne sound to the crankcase. This known type of design 
suffers from the disadvantage that the sound-insulating elements will have 
to be rather rigid on account of their being part of the flow of force 
between combustion chamber and crankshaft, which will permit a fairly 
precise alignment of the crankshaft axis and the adjoining driven parts, 
but will greatly reduce the sound-insulating properties of the assembly. 
Besides, the sound-insulating elements are badly exposed to the 
hot-motor-oil in this type of design. 
Another combustion engine of the abovementioned type is finally known from 
German laid-open print No. 28 49 860, in which individual sound-insulating 
elements are located outside of the crankcase area sealed against oil by a 
special flexible sealing element, and are therefore not subject to attack 
by the hot lubricant. The axes of these hollow, cylinder-shaped elements 
insulating against structure-borne sound run parallel to the axis of the 
crankshaft. With regard to the requirements of modern "crash tests," this 
arrangement has proved to be of great advantage for all motor vehicles 
whose combustion engines are positioned transversely to the long axis of 
the vehicle--a design characteristic of the majority of modern cars--, 
since the permissible radial deformation or stress of such flexible 
elements is much higher than the corresponding values in the axial 
direction. Due to the rather elevated position of the flexible elements 
relative to the crankshaft axis, this design variant will permit larger 
relative movements between crankshaft and crankcase or the adjoining 
engine components, however, which may require the use of a flexible output 
coupling or of special elements restricting the movement of the engine 
unit support in the area of the crankshaft axis. 
SUMMARY OF THE INVENTION 
It is an object of the present invention to improve combustion engines of 
the abovementioned type by modifying the way of mounting the engine unit 
support in the crankcase while maintaining the favorable location of the 
sound-insulating and force-transmitting elements between engine unit 
support and crankcase outside of the oil-wetted area of the crankcase, and 
thereby reducing the possible movements between crankshaft and crankcase 
in a simple manner at the same time. 
According to the present invention this is achieved by providing a bracket 
of at least two arms at least at the output end of the engine unit 
support, which bracket is attached to the bearing seat of the crankshaft 
and is provided with at least one sound-insulating element at each end, 
and by positioning the sound-insulating elements symmetrically with 
respect to the crankshaft axis. This particular arrangement of insulating 
elements relative to the crankshaft axis will reduce the relative 
movements of the engine unit support which are made possible by the 
flexibility of the insulating elements, and will limit them to a swinging 
movement around the crankshaft axis itself, thus eliminating the need of 
separate compensating elements or stops at the output end of the engine 
unit support. 
In an enhanced version of this invention a two-armed bracket is to be 
mounted on either end of the engine unit support, with the symmetry axes 
of the brackets through the sound-insulating elements and the crankshaft 
axis being inclined towards each other at an angle of approximately 90 
degrees, as seen in the direction of the crankshaft axis. This X-type 
arrangement of the brackets will reduce the swinging movements of the 
engine unit support relative to the crankcase in a simple and most 
satisfactory way, while permitting the sound-insulating suspension to 
remain fully effective. The two-armed bracket can be manufactured easily 
and may be placed at an oblique angle relative to the center plane of the 
engine--as seen in the direction of the crankshaft axis--, which 
eliminates the need for widening the crankcase. 
The invention may be further improved by providing the bracket with center 
holes which--together with center pins to be inserted into respective 
holes in the crankcase--will indicate the accurate position of the 
crankshaft axis during the assembly of the engine unit support. This will 
permit a much simpler way not only of mounting the engine unit support but 
also of replacing the sound-insulating elements, since the relative 
position between engine unit support and crankcase, and thus between 
crankshaft axis and adjacent output elements, may be perfectly adjusted 
even before inserting the sound-insulating elements. 
According to another proposal of the invention, setting elements may be 
used to great advantage in this context in order to adjust the position of 
the sound-insulating elements borne by the brackets relative to the 
crankcase in such a way as to make the preloading of the sound-insulating 
elements completely independent of this adjustment. Experience has 
frequently shown that in combustion engines whose engine unit supports are 
suspended in the crankcase by means of sound-insulating elements, the 
possible degree of sound insulation will largely depend on manufaturing 
and mounting tolerances, since--due to the sound-insulating elements being 
attached to the engine unit support, or rather to the crankcase--these 
tolerances will directly lead to differences in the preloading of the 
individual flexible elements of all variants known, which will result in 
different vibration and damping characteristics. This disadvantage is 
eliminated by making the sound-insulating elements adjustable before they 
are fully fastened in place. 
According to a further enhancement of the invention, the setting elements 
are configured as washers of a graded thickness, which may be inserted 
between the crankcase and a mounting flange at the sound-insulating 
element in question. This simple device will permit easy adjustment of the 
sound-insulating elements. 
In another variant of the invention, the bracket is a pressed part made of 
sheet metal and reinforced by beading, which will simplify manufacture and 
will have little bearing on either weight or the exterior dimensions of 
the internal combustion engine. 
In order to avoid moments of torsion in the bracket, another improvement of 
the present invention envisages that each end of the bracket be provided 
with two suitably aligned insulating elements between which the bracket is 
braced firmly. 
The internal combustion engine illustrated in FIGS. 1 through 6, which 
might be found in an automobile, is attached and mounted in an entirely 
conventional manner by means of additional flexible elements and consoles 
which are screw-fastened to the vehicle frame and to the crankcase or the 
gearbox case. This particular flow of force may lead to comparatively high 
stresses and deformations in the crankcase, which may impair the 
efficiency of sound reduction due to the reduced sound-absorption by the 
crankcase. In order to facilitate mounting of the entire combustion engine 
without affecting the insulation of structure-borne sound, a further 
improvement is concerned with providing brackets for both ends of the 
engine unit support, one of which will bear at least one additional 
sound-insulating element and the other at least two additional 
sound-insulating elements positioned at opposite ends, which are not 
connected to the crankcase but located outside of it, and which are used 
for the purpose of supporting the internal combustion engine, e.g., in a 
motor car it powers. In this way the crankcase no longer has to transmit 
the forces originating at the engine unit support to the mounting elements 
of the internal combustion engine, which will prevent any stresses and 
deformations impairing the sound-damping qualities of the crankcase from 
occurring in the vicinity of the mounting elements. 
Another enhanced version of the present invention proposes that the 
additional sound-insulating elements each be placed at one end of the 
bracket together with the sound-insulating elements holding the engine 
unit support in the crankcase. Thus the bracket will not require any 
modifications as compared to the variant of the engine unit support being 
directly borne by the crankcase; only the fastenings of the 
sound-insulating elements at the ends of the bracket arms will have to be 
modified in order to enable the additional sound-insulating elements 
supporting the internal combustion engine to be attached as well. 
Finally, a further elaboration of the invention provides a separate bracket 
arm for each of the addition sound-insulating elements, with its end 
projecting from an opening in the crankcase, carrying a cover for 
preventing the radiation of sound in this area. In this way the mounting 
elements of the combustion engine itself are independent of the elements 
attaching the engine unit support to the crankcase, which will permit an 
individual selection of the ideal places for fastening the 
sound-insulating elements. Since the brackets are located outside of the 
oil-wetted area of the crankcase, the openings through the crankcase for 
the additional bracket arms will have to be made sound-proof but not 
oil-tight.

DESCRIPTION OF THE PREFERRED EMBODIMENTS 
The internal combustion engine illustrated in FIGS. 1 to 3 is provided with 
an engine unit support 1 comprising such sound-generating components as 
cylinders 2, cylinder head 3, pistons and piston rods (not shown here), 
crankshaft bearings 4 and crankshaft 5, which is attached to the crankcase 
6 by means of sound-insulating elemts; as a consequence, the crankcase 6 
itself is sound-insulated as well. For this purpose, the engine unit 
support 1 is supplied both at the output end 7 and at the opposite end 8 
with a two-armed bracket 9 which is fastened with screws 10 to the 
outermost bearing seats of the crankshaft bearings 4 or to the engine unit 
support 1 in the vicinity of the outermost crankshaft bearing seats, and 
which bears two sound-insulating elements 12 at each of its ends 11. In 
the variant illustrated, the sound-insulating elements 12 consist of an 
inner cylinder or jacket 13, of an outer cylinder or jacket 15 provided 
with a mounting flange 14 and of an elastic material 16 filling the space 
between the two cylindrical jackets, which prevents the propagation of 
structure-borne sound between the inner jacket 13 and the outer jacket 15 
and any further parts connected to them. 
The sound-insulating elements 12 are fastened to the brackets 9 with 
through-bolts 17 which will press the inner jackets 13 of two elements 
opposing each other against the brackets 9. The outer jackets 15 are 
attached to the crankcase 6 or rather to the flywheel housing 18 
connecting to the crankcase by means of mounting flanges 14, which are 
fastened to special lugs 20 on the crankcase or flywheel housing with 
through-bolts 19. In order to prevent the radiation of sound via the inner 
jackets 13 and through-bolts 17 connected to the sound-carrying engine 
unit support, the sound-insulating elements 12 are provided with covers 
21; on the side of the engine unit support bearing the drive 22 for the 
overhead camshaft (not shown here), both the sound-insulating elements 12 
and the camshaft drive 22 are covered by a cover 23. 
At ends 7 and 8 the engine unit support 1 is provided with flexible oil 
seals 24 sealing the interior of the crankcase 6 against the loss of oil; 
as they do not bear any structural load they are of a material soft enough 
to inhibit the transmission of any structure-borne sound from the engine 
unit support 1 to the crankcase 6. The crankshaft itself is sealed against 
oil-loss by rotary shaft seals 26 both at the side of the flywheel 25 and 
at that of the camshaft drive 22. FIG. 1 also shows the seal at the upper 
edge 27 of the crankcase 6 against the engine unit support 1. For this 
purpose a flexible sealing element 29 (schematically indicated in this 
drawing) is inserted into a groove 28 running along the entire 
crankcase,--again without any load-bearing function. 
The sound-insulating elements 12 are thus positioned outside of the 
crankcase interior and are therefore not exposed to the spray of hot 
lubricant, which greatly extends the life of these elements. 
As is revealed by FIGS. 2 and 3, the sound-insulating elements 12 which are 
shaped as hollow cylinders, are positioned such that their axes run 
parallel to the axis of the crankshaft 5. In view of a marked preference 
of the modern car designer for a transverse position of the engine 
relative to the vehicle's longitudinal axis, this positioning is of 
advantage as it permits the sound-insulating elements to absorb the high 
accelerations required during the so-called "crash-tests" with small 
radial deformations only. 
Furthermore, it is of particular advantage that the arrangement of the 
sound-insulating elements 12 is symmetrical with respect to the axis of 
the crankshaft 5, since with this arrangement the relative movements 
between the engine unit support 1 and the crankcase 6, which are made 
possible by the flexibility of the sound-insulating elements 12, will be 
reduced to a swinging movement around the axis of the crankshaft 5, 
thereby eliminating the necessity of stops or flexible linkages at the 
output end of the crankshaft, which would otherwise be required for 
restricting the movements of the crankshaft relative to other output 
elements not shown in this drawing. 
Another advantage of the internal combustion engine represented here is 
that the crankcase may be of the one-piece die-cast type due to the 
particular mounting system used for the engine unit support. 
As a variant to the embodiment shown, a multi-armed bracket would be 
conceivable, with at least one sound-insulating element at each of its 
ends for attaching the engine unit support to the crankcase. 
FIGS. 4 and 5 are concerned in detail with the arrangement of the 
sound-insulating elements of an internal combustion engine as specified. 
Bracket 9 is fastened with screws 10 to the engine unit support 1, or 
rather to the crankshaft bearing seats opposite of the flywheel (not shown 
here); in this variant it consists of a pressed part 30 made of sheet 
metal and of a special reinforcing part 31 in the area subject to the 
greatest load between the screws 10 and the through-bolt 17. It has an 
opening 32 for the through-bolt 17 at its end 11, which is used for 
attaching the inner jackets 13 of the sound-insulating elements 12 to 
either side of the bracket 9. The outer jacket 15 which is sound-insulated 
from the inner jacket 13 by means of the flexible material 16, is provided 
with a mounting flange 14 with through-holes 33 for further through-bolts 
19 positioned symmetrically to the through-bolt 17, which are used for 
fastening the sound-insulating elements 12 to a lug 20 of the crankcase 6 
or to a separate part 35 fastened with screws 34 to the lug 20 of the 
crankcase 6. The screw 34 has sufficient play relative to a bore 36 at end 
11 of the bracket 9 in order to ensure that the relative movements between 
the engine unit support 1 and the crankcase 6, which are made possible by 
the flexible elements 12, will not be impeded during operation of the 
internal combustion engine. In addition to fastening the separate part 35 
to the lug 20 of the crankcase 6, the screws 34 are used for fastening the 
cap 21 and the cover 23 with the help of distance sleeves 37, 38, the 
cover 23 being made vibration-proof by means of an additional flexible 
element 39 in this variant. 
As discussed under FIGS. 1 to 3, a flexible oil seal 24 is placed between 
the engine unit support 1 and the crankcase 6, which--together with the 
sealing elements at the upper edge of the engine unit support and at the 
outermost crankshaft bearings (not shown here)--will ensure that the 
sound-insulating elements 12 are located outside of the oil-wetted 
interior of the crankcase 6. 
As can be seen in FIG. 5, setting elements 40 in the shape of washers are 
positioned between the crankcase, or rather the lug 20 and the separate 
part 35, and the mounting flange 14 of the sound-insulating elements 12, 
which will permit adjusting the position of the adjoining elements 
relative to each other in the direction of the axis of the 
sound-insulating elements 12 in such a way as to make the preloading of 
the assembled sound-insulating elements 12 independent of any tolerances 
resulting during manufacture or assembly of the internal combustion 
engine. Since the washers 40 are replaceable it will be possible to select 
a washer of adequate thickness during the assembly of the internal 
combustion engine or upon replacement of a sound-insulating element. In 
combunation with the through-holes 33 which are slightly larger in 
diameter than would be necessary for the screws 34, this is a simple 
device for eliminating any uncontrollable and undesirable preloadings of 
the individual sound-insulating elements which would lead to different 
sound-damping characteristics. 
The arrangement according to FIG. 6 differs from that of FIG. 4 in so far 
as in FIG. 6 the sound-insulating elements 12 are shown on the output side 
of the engine unit support or rather on the side of the flywheel 41. The 
elements 12 again are attached to the bracket 9'--a pressed sheet metal 
part reinforced with beadings 42--and to the crankcase 6 and to the 
flywheel housing 18 or to the respective lugs 20. An oil-sump 44 is 
attached to the crankcase 6 cushioned by a seal 43; furthermore, the 
flywheel 41 contains a toothed wheel rim 45 meshing with a starter pinion 
(not shown). 
FIG. 6 shows the arrangement of the sound-insulating elements 12 with the 
covers removed during the assembly of the internal combustion engine or 
while one of the sound-insulating elements is being replaced. Instead of 
the screw 34 a center pin 46 has been inserted, fitting loosely into the 
bore 36 at the end 11 of the bracket 9, which serves for the accurate 
adjustment of the relative position of the engine unit support and the 
crankcase during the assembly of the internal combustion engine. In order 
to prevent the bracket 9' from being bent or damaged during the insertion 
of the center pin 46, a sleeve 47 is inserted from the side of lug 20 of 
the flywheel housing 18, with a bore for holding the center pin. 
During the assembly of the combustion engine or the replacement of the 
sound-insulating elements the center pin 46 may be used for aligning the 
engine unit support relative to the crankcase before the sound-insulating 
elements are being fastened and the tolerances are being compensated in 
the manner described in detail under FIG. 5. 
The internal combustion engine schematically indicated in FIG. 7 differs 
from that in FIG. 3 by the use of two brackets 9 at the opposite ends of 
the engine unit support, which are positioned such that they include an 
angle 48 as seen in the direction of the axis of the crankshaft 5. Due to 
this arrangement the movements of the engine unit support 1 relative to 
the crankcase 6, which are made possible by the flexible sound-insulating 
elements 12, are reduced to a minimum in a simple manner without impairing 
the sound-insulating properties. 
The internal combustion engine illustrated in FIGS. 8 to 10 is provided 
with an engine unit support 1 which comprises the sound-generating parts 
of the engine (not shown in detail) and is held in the crankcase by 
sound-insulating elements, thus rendering the crankcase 6 itself 
sound-proof. For this purpose a four-armed bracket 9" is mounted on either 
side of the engine unit support 1, which is fastened with screws 10 to the 
outermost seats of the crankchaft bearings (not shown here). While two of 
the ends 11 of this bracket 9", which are opposed to each other with 
respect to the axis of the crankshaft 5, will serve as a sound-insulating 
suspension of the engine unit support 1 in the crankcase 6, its other two 
ends 52, which again are opposed to each other with respect to the axis of 
the crankshaft 5 and whose symmetry axis 49 includes an angle 50 with the 
symmetry axis 51 of the ends 11, are used for directly mounting the engine 
unit support and thus the entire combustion engine on a vehicle frame 
indicated by parts 53 and 54 in this drawing. 
The flexible suspension of the engine unit support 1 in the crankcase 6 via 
the ends 11 of the bracket 9" can be seen more clearly in FIG. 10. The end 
11 of the bracket 9" which is a two-part pressed component made of sheet 
metal in this variant, has an opening 55 holding a screw 56 which will 
fasten two sound-insulating elements 12 by pressing the inner jackets 13 
against the bracket 9". The outer jackets 15 of the sound-insulating 
elements 12 are insulated against vibrations from the inner jackets by 
means of a flexible material 16, and are inserted into mounting elements 
57, which are attached to suitable mounting surfaces 58 on the crankcase 6 
with screws 59. In order to prevent the radiation of sound from the screws 
56 or from ends 11 of the bracket 9", the mounting elements 57 are 
provided with covers 60 and 61. 
FIG. 9 illustrates in which way the ends 52 of the bracket 9" are attached 
to the frame element 54 of a vehicle (not shown here). This variant also 
includes a separate mounting element 62 which is fastened to the frame 
element 54 with screws indicated by their axes 63 in FIG. 8, and will hold 
the outer jackets 64 of two sound-insulating elements 65. The inner 
jackets 67 which are sound-insulated from the outer jackets 64 by means of 
a flexible material 66, are attached to the end 52 of the bracket 9" with 
a through-bolt 68. Those parts into which structure-borne sound from the 
engine unit support 1 is directly fed via the bracket 9", are again 
provided with covers 60, 61 in order to prevent the sound from radiating 
into the environment. 
The openings 70 and 71 of the crankcase from which the additional bracket 
arms 69 project, are sound-proofed by means of flexible sound-absorbing 
covers 72, 73--the crankcase 6 already being oil-sealed in the vicinity of 
the brackets 9" in a manner not shown here. 
The above system of mounting an internal combustion engine, e.g., in a 
motor vehicle it powers, will ensure in a most advantageous way that the 
reaction forces of the engine unit support are directly transmitted to the 
elements supporting the combustion engine, thereby preventing stresses and 
deformations in the crankcase which would be caused if the reaction forces 
were picked up by the crankcase and would drastically reduce the 
sound-insulating properties of the crankcase. 
In the variant illustrated in FIGS. 11 to 13, the additional 
sound-insulating elements 65 which are used for mounting the combustion 
engine on a frame element 54 of a vehicle not shown, each are attached to 
an end 11 of the bracket 9' together with the sound-insulating elements 12 
fastening the engine unit support (not shown in this drawing) to the 
crankcase 6. The inner jackets 13, 67 of the elements 12, 65 are fastened 
to the end 11 of the bracket 9' with one common through-bolt 74; as to the 
arrangement of the outer jackets 15, 64 and the mounting elements 57, 62 
at the crankcase 6 or at frame element 54, cf. description of FIGS. 8 to 
10. 
As before, the reaction forces of the engine unit support will not be 
picked up by the crankcase since they are directly transmitted to the 
frame elements 54 via the brackets 9' and the additional sound-insulating 
elements 65. Thus the sound-insulating function of the crankcase itself is 
not impaired. 
As a variant of the arrangement shown in FIG. 8 one side of the engine unit 
support could be provided with a bracket including one additional 
sound-insulating element only for supporting the combustion engine, which 
would result in a three-point mounting system.