Internal Combustion Engine With Silencing Means

Abstract

In an internal combustion engine of the type having a closed cooling air conducting system associated with the engine cylinder or cylinders, a cooling air blower in the system, sound muffling means associated with the system, and an air filter through which combustion air is introduced to the cylinder or cylinders, long sound deadening channels are provided without a simultaneous increase in the overall constructional size of the engine. The inlet side of the conducting system is made of a maximum length utilizing the free-space which is available at the outer side of the engine, the filter is fastened from the exterior to a wall of the conducting system to receive air from the interior of the conducting system, the suction tube of the cylinder or cylinders is arranged within the conducting system to communicate with the discharge of the air filter, and the exit side of the conducting system is made of maximum length by utilizing the free space available at the outer side of the engine, and surrounds the exhaust conduit of the cylinder or cylinders.

Description

This invention relates to internal combustion engines which have a closed cooling air conducting system including a cooling air blower, which have sound-muffling means associated therewith, and in which incoming air is passed through an air filter.

In air-cooled internal combustion engines there is always a problem of reducing the dissemination of noise which is set up in the parts of the engine, and it has been sought to accomplish this by noise-deadening expedients, for example by the use of channels lined with rock wool or the like arranged upstream and downstream of the noise-engendering parts of the engine. To obtain an acceptable degree of sound suppression the channels equipped with noise-deadening expedients (the so-called muffling passages) must not be below a minimum size. To increase the efficiency the aforesaid passages are simply extended in length. This, however, leads to a substantial increase in the constructional size of the engine.

It is an object of this invention to provide a sound-deadening arrangement which permits a substantial effective increase in the length of the sound suppression channels without a simultaneous increase in the overall constructional size of the engine, and moreover which simultaneously deadens noise in the cylinders, the blower, and the suction or exhaust elements of the engine.

In pursuance of this object in accordance with the present invention we provide an internal combustion engine comprising an engine block including at least one combustion cylinder with at least one air admission port and at least one gas exhaust port, a closed cooling air conducting system associated with said cylinder, a cooling air blower in said system, sound-muffling means associated with said system, and an air filter through which combustion air is introduced to said cylinder, characterised by the fact that the said conducting system comprises air admission and air discharge ducting sections arranged respectively upstream and downstream of said cylinder and externally of the engine block; the air filter is mounted on the engine block for access from the exterior of the latter and has an air admission and air discharge ducting sections and an air discharge port communicating with a suction tube connected to the admission port of said cylinder; and the cylinder has an exhaust conduit connected to said exhaust port and disposed within the air discharge ducting section.

In the case of internal combustion engines with aligned cylinders, in accordance with a special feature of the invention the free space available in the engine is utilised to a maximum extent by making the air admission ducting section in the form of an elongated tube which is disposed laterally of and along the row of cylinder heads. If in arrangements of this character a flywheel is provided on the crankshaft, in accordance with a preferred embodiment of the invention the said tube has an air admission opening at the side of the engine block at which the flywheel is disposed, and an air filter is incorporated in the cooling air conducting system, being fastened in horizontal disposition to a wall of the conducting system at the same side of the engine block as the flywheel.

In single-cylinder internal combustion engines the elongation of the muffling passage now sought is obtained in accordance with a feature of the invention in a very satisfactory fashion by making the air admission section in the form of tubular ducting which is disposed round said cooling air blower in spiral or volute form. It is advantageous in this case to arrange that said tubular ducting is provided with an air admission port substantially at the uppermost part thereof, and an air filter is disposed upright in the cooling air conducting system in a wall of the latter adjacent the head of the cylinder. In this event the air will be drawn in at an elevated position and, despite the air filter employed, no installation space is wasted.

A likewise very compact and efficient elongation of the conduit system at the discharge side is obtained, in conformity with a further feature of the invention, by making the air discharge ducting section in the form of a flat channel which extends approximately parallel to the engine cylinder and is open at the bottom.

In accordance with a particularly advantageous feature of the invention, a cyclone separator or other contaminant-removing means is disposed in the cooling air conducting system upstream of the air admission port of the air filter. The means for removing contamination do not then take up additional installation space and a further favourable compactness is achieved.

Advantageously the inner walls of the cooling air conducting system are furnished with at least one layer of rock wool as a sound-deadening medium. This layer is advantageously held in the requisite position against the wall by means of a covering sheet of mesh or perforated plate so that these layers will not interfere with the functioning of the apparatus. Further, the cooling air blower will likewise be lined with a layer of rock wool for the purpose of providing additional sound-deadening at the wall of the housing thereof.

A further and notable increase in the sound-deadening effect is achieved in accordance with a further feature of the invention if the air admission ducting section and/or the air discharge ducting section is or are angled in relation to the cooling air blower to induce at least one change in direction in the flow of cooling air therethrough.

Examples of embodiments of the invention are described below with reference to the accompanying drawings, in which:

FIG. 1 is a side view, partly in section on the line I--I FIG. 2, of a first embodiment of the invention applied to a multi-cylinder injection internal combustion engine,

FIG. 2 is a corresponding front view, partly in section on the line II--II, FIG. 1,

FIG. 3 is a plan view corresponding to FIG. 2,

FIG. 4 shows a detail of this first embodiment on an enlarged scale,

FIG. 5 is a side view, partly in section on the line V--V FIG. 6, of a second embodiment of the invention applied to a single-cylinder internal combustion engine,

FIG. 6 is a front view corresponding to FIG. 5, partly in section on the line VI--VI of FIG. 5, and

FIG. 7 is a plan view corresponding to FIG. 5.

FIGS. 1-4 illustrate a four-cylinder internal combustion engine of conventional construction. The cylinders 10a, 10b, 10c, 10d, are arranged upright in a row and are mounted on a common crank case 12. The horizontal crankshaft 14, driven by pistons (not shown) in the cylinders carries a V-pulley 16 at one projecting end and a flywheel 18 at the other end. Flywheel 18 is equipped with means, for example a driving flange, for operation of the units which are to be driven by the engine.

Secured on each cylinder is a cylinder head 20a, 20b, 20c, 20d respectively, this head containing valves and associated operating components, for example injection elements and so on. The elements in each cylinder head are accessible through a removable cylinder cover 22a, 22b, 22c, 22d respectively. The cylinders and cylinder heads, which are subject to very high operating temperatures, have therearound cooling fins which are exposed to a flow of cooling air in conventional fashion. This cooling air flow is produced by a rotary blower wheel 24 with blades 24a arranged at its periphery, and it is routed by a conducting or baffle plate 26 so as to flow first along the row of cylinders and then transversely thereto, that is to say between the individual cylinders, to be collected at the opposite side and carried away. The arrows in FIGS. 1 and 2 illustrate the path of flow of the cooling air. The blower wheel 24 is arranged on a shaft 24b mounted in the first cylinder 10a, and it is driven from the wheel 16 through a V-pulley 28.

The channels through which the cooling air flows are lined with sound-deadening means, and to increase their effective length without increasing the dimensions of the engine in the present invention these channels (also referred to as muffling passages) are installed as illustrated so as to utilise the free outer areas of the engine. Disposed at the suction side of the blower 24 is a long tubular duct or channel 30 arranged in the free area between the conducting plate 26 and the cylinder head covers 22a, 22b, 22c, 22d along the row of cylinders. The admission port 30a of duct 30 is disposed at the flywheel end of the engine so that cooling air drawn in at 30a is first conducted oppositely to the direction of flow of the cooling air within the conducting plate 26, is then given a change of direction of 90.degree. by a band 30w in duct 30, and finally drawn through blower 24 with another change of direction of 90.degree..

The discharge end of the cooling air conducting system is in the form of a flat, downwardly tapering and downwardly open duct or channel 32 which is substantially parallel to the line of cylinders. The cooling air from between the cylinders is collected here and conducted to atmosphere through the bottom gap 32a. The exhaust conduits 34a, 34b, 34c, 34d of the individual cylinders are connected to an exhaust manifold in the form of a single tube 34 which opens into channel 32 so that the exhaust or combusted gases are conducted away with the cooling air at 32a. (The tube 34 might also have arranged behind it an exhaust cup of a known type for sound-deadening purposes, and this could also be arranged inside channel or duct 32).

A change in direction of the air flow through about 90.degree. also takes place in channel 32. The silencing effect is still further increased by the changes in direction of flow within the air conducting system, this having been extended to a maximum at both sides of the blower to muffle the noise.

The ducts 30 and 32 and also the conducting plate 26 are defined by shaped components which conform with one another and can be readily secured to the engine housing by appropriate means, for example screws. The method of attachment has not been illustrated to avoid confusion of the remainder of the drawing. As can be seen from the sectional illustration, the wall of each of these ducts, for example of sheet metal, can have a carrying function and support silencing or sound-muffling media, for example a layer or rock wool, at the side exposed to the flow of cooling air. This layer is in turn covered by a retaining means, for example a mesh or perforated sheet.

For the sake of simplicity the ducts 26, 30, and 32 are illustrated in FIGS. 1-3 in simple section. In practice, however, the wall of duct 26 will for example have the cross-sectional form illustrated in FIG. 4. The carrier wall plate 26 is lined internally by a layer 26a of rock wool and this is retained by plate 26b of conforming shape provided with fine perforations. The perforated plate 26b is connected to the wall 26 by screws (not shown) and this wall 26 is anchored in turn to the engine block. The ducts 30 and 32 are equipped and arranged in the same way.

Arranged in duct 26 is a suction tube 36 with ports 36a, 36b, 36c, 36d connected to the admission ports in the cylinder heads 20a, 20b, 20c, 20d. An air filter 38 disposed upstream of the suction tube 36 is so arranged that it takes the combustion air from duct 26 and conducts it to the admission port 36t of suction tube 36. The casing of the air filter 38, which is of cup form, is connected from the exterior to the end 26s of duct 26, for example is screwed at this end, so that the inlet port to a cylindrical paper insert 36p in this filter communicates with an annular opening 26ss of duct 26. A contaminant-separator, for example a cyclone separator 40 of known form with blade walls 40a producing a volute effect, is mounted in duct 26 concentrically in relation to admission port 36t and upstream of port 26ss. Large particles of contaminant which may still penetrate into the interior of the duct are picked up by the cyclone separator 40 and discharged through a discharge opening 40t in the wall of duct 26.

The combustion air will thus pass from the interior of duct or channel 26 through the cyclone separator 40 and through port 26ss into the interior of air filter 38, to be filtered by the insert 38p and conducted to the central admission port 36t of suction tube 36, which in turn takes care of the distribution to the individual cylinders. With the air filter disposed in this way maintenance thereof can be performed from the exterior without having to dismantle any parts of the ducts 26 and 30.

With the form and arrangement of the admission and discharge ducting sections of the conducting system, i.e., the so-called muffling passages upstream and downstream of the blower, in accordance with the present invention, these sections have been afforded maximum length and maximum cross-sectional area without making the overall dimensions of the engine larger than would otherwise be prescribed for it. The muffling passages bring about a suppression of the noise which occurs in the internal enclosed elements, or is generated by these, with maximum efficiency, allied with a conduction of cooling air. The noise referred to is generated for example at the blower 24, at the means 16, 28 for driving the same, in cylinders 10a, 10b, 10c, 10d, in cylinder heads 20a, 20b, 20c, 20d, and in the suction and exhaust parts 36 and 24. (The crankcase 12 is equipped with its own individual silencing means which have not been shown here, for example baffles). The changes in direction of flow induced by the shaping of the ducting or muffling passages confer an advantageous increase in the silencing effect. The arrangement of the air filter which is accessible from the exterior, despite taking air from the stream of cooling air, also caters for very simple servicing.

Reference should also be made to the fact that the air flow is, with advantage, drawn in at the uppermost part of the engine, namely at 30a, where it has a higher degree of purity. Thus only a quite negligible quantity of large contaminating particles passes into the cooling air conducting system. The downward air discharge through the gap 32a in the system is also of advantage.

The construction and arrangement of the ducting as used in this invention for the conduction of cooling air and simultaneous sound-suppression can also be used in single-cylinder internal combustion engines, as is illustrated by the second embodiment of the invention illustrated in FIGS. 5-7. In overall construction the engine shown here is similar to that of the engine illustrated in FIGS. 1-4, wherefore like parts in the two cases have been given the same reference numerals, but in the case of FIGS. 5-7 accompanied by a prime. For this reason a repeated description of the general construction of the engine is unnecessary.

In FIGS. 5-7 the blower 24' and the cylinder 10', with its cylinder head 20', are surrounded by a cooling air conducting ducting 126 at the admission side, and cooling air is conducted through this ducting between and over the cooling fins at the periphery of the engine parts 10' and 20' and allowed to pass into the discharge duct 132. The exhaust air passes to atomsphere through the bottom gap 132a in this duct 132. Provided at the admission end is a duct 130 upstream of the duct or channel 126, and this takes the form of a tubular duct or tube which conducts the air in a volute or spiral path to the blower 24' as clearly seen in FIG. 5. The admission port 130a of tube 130 again is here at the uppermost part of the engine.

The air filter 138 is secured to the outer wall of duct 126 from above, this making it readily accessible for maintenance. The air passing at 126ss from the cooling air stream into the interior of air filter 138 passes through the paper filter insert 138p and through the central port 136t into the suction tube 136. The exhaust tube 134 here again leads to the air discharge duct 132.

The spiral or volute form of the admission channel 130 here again provides a form of construction which secures a maximum length and maximum cross-section of the cooling and sound suppressing passage at the admission side. In this second embodiment therefore the same advantages are secured with a single cylinder internal combustion engine in relation to the sound suppression, cooling, and the disposal of the air filter, as were obtained in the first example. It is also to be pointed out that in this second embodiment the ducts 126, and 130 and 132 are of course also provided with layers of rock wool for sound-deadening purposes, wherefore the wall construction will be similar to that illustrated in section in FIG. 4.

Finally, it is to be understood that the invention is not limited to the particular forms of embodiment which have been specifically illustrated and described. In particular the ducting system at the admission end can be installed in the outer free areas of internal combustion engines of various constructions, and the muffling passages required can be made of a form other than that actually illustrated. Moreover other suitable sound-deadening means of known kind can be used in the ducts or muffling passages instead of the rock wool described.

Claims

What we claim is:

1. In an internal combusion engine having a row of cylinders, combustion air intake and discharge pipes, and a closed coolant air conduit system that includes an air fan, with which conduit system noise damping means are associated, the combustion air being introduced via an air filter, the improvements wherein the intake side of the conduit system includes a relatively long duct arranged along, laterally of and above the cylinder heads of the row of cylinders, the intake opening of the duct being at a first end of the row and the discharge end of the duct leading to the fan, said fan being arranged at the other end of said row and being connected with the air filter at the first end of the row by a passage defined by a guide plate lying laterally beside and along the row of cylinders, said filter receiving coolant air and leading it to the combustion air intake pipe of the engine, whereby the damping length on said intake side is at least as long as the row of cylinders, the discharge side of the conduit system including a flat channel disposed closely adjacent and along the row of cylinders and cylinder heads and extending downwardly along and adjacent the crankcase of the engine, said flat channel also surrounding the combustion exhaust pipe of the engine, such that the damping passage on the discharge side is approximately of the height of the engine.

2. A combustion engine as claimed in claim 1, further including a flywheel seated on the crankshaft of the engine, the intake opening of said relatively long duct being provided on the flywheel end of the engine, and the air filter being removably fixed from the outside on a wall of the conduit system.

3. A combustion engine as claimed in claim 1, wherein noise damping means comprising at least one layer of rock wool is disposed on all inner walls of said conduit system.

4. A combustion engine as claimed in claim 3, wherein said air fan is enclosed by the conduit system and is also covered on its housing walls with a layer of rock wool for additional noise damping.