EP1079080B1 - Oil cooled internal combustion engine - Google Patents

Abstract

The engine has an engine block with a cylinder housing and cylinder head and a cooling sleeve carrying an oil flow and contg. an annular chamber (10) enclosing a piston working chamber and a head chamber (11) almost fully covering the working chamber at the end, whereby the head chamber and annular chamber are directly connected. The oil flow passes from the cooling sleeve via an outlet opening (13) in the head chamber into a return chamber (14) enclosing at least one cylinder (6) including the annular chamber.

Description

The invention relates to an internal combustion engine having an engine block which has a cylinder housing and a cylinder head covering the cylinder head and a cooling jacket through which oil flows, wherein the cooling jacket, an annular space axially at least partially surrounding the working space of a piston and a head space almost completely covering the working space , wherein the headspace and the annulus are in direct communication with each other.

Such oil-cooled internal combustion engines are known in particular among diesel engines. In the known engines, the cylinder block is provided in the immediate vicinity of the cylinder with cooling chambers, which are traversed by a stream of oil to dissipate the heat of combustion. The use of oil as a coolant has the particular advantage that it can be completely dispensed with cooling water. The elimination of cooling water is accompanied by the solution of many problems that brings the actually "motor-foreign" water with it. In addition, the operating temperature of water-cooled engines is limited to about 95 ° C because of the physical properties of the coolant, which limits the degree of energy conversion and emissions reduction.

As the closest prior art DE 35 08 405 A is considered, which is an oil-cooled engine in which a first annulus surrounds the cylinder and a second annulus is in communication with the first.

A disadvantage of the previously known oil-cooled engines is that the cooling can be relatively poorly controlled. So it can come in the known engines to different heating of the individual parts and thus to tensions and even cracks in the engine block. simultaneously It may come because of locally occurring "hot spots" to a partial coking and thus contamination of the cooling oil, resulting in a deterioration of the cooling performance.

Object of the present invention is to provide an oil-cooled internal combustion engine, which can be operated even at relatively high temperatures. In addition, it is the object of the invention to provide an internal combustion engine of simple construction and high reliability, which allows a good heat regulation by controlling the cooling oil flow and thus allows an optimization of the energy conversion.

This object is achieved by the internal combustion engine according to claim 1.

The central idea of the invention lies in the fact that the engine according to the invention with its multi-chamber system surrounding the cylinders for oil guidance and oil intake allows a precise control of the temperature by controlled oil flow and good heat dissipation. This special feature of the motor makes it possible to allow comparatively high operating temperatures of up to 140 ° C or above. For such high operating temperatures, however, the use of a metal gasket as a cylinder head gasket is essential.

For the realization of the controlled cooling, it is first important to cover the working space (displacement) of the cylinder as completely as possible with a cooling jacket. For this purpose, the cooling jacket on the one hand a coaxial to the cylinder displacement at least partially surrounding annular space, which continues in a combustion chamber, the front side covering headspace. In this case, the head space is designed so that it almost completely covers the respective cylinder head and the combustion chamber arranged therein. The headspace is broken only by the necessary feedthroughs for the injector or the valves. According to the invention, the oil flow enters the return space from the cooling jacket via an outlet opening introduced into the head space, wherein the return space completely surrounds the cylinder, including the annular space. That's one Optimal control of heat dissipation possible. In addition, the enveloping cooling jacket and the return chamber contribute to noise reduction.

In a particularly simple embodiment, the annular space and the headspace directly merge into one another at the location of the cylinder head gasket and form a closed cooling jacket of approximately constant width. Thus, a homogeneous flow of the oil is achieved without strong pressure fluctuations due to bottlenecks. The return space is advantageously arranged parallel to the piston and forms the oil sump at its lowest point. On its vertical walls, the oil runs down and cools down before, due to gravity at the lowest point in a collection space, especially in the oil sump runs. In a hydrodynamically particularly favorable and easy to implement embodiment, all cylinders of the engine are surrounded by a common return space. At the same time, gases from compression losses flow upwards to the valve covers in the return area and can be removed from there.

In a particularly advantageous embodiment, the oil is conveyed by a particular electrically operated pump. The oil flow enters the cooling jacket from below via an inlet opening provided in the vicinity of the bottom of the annular space and is conveyed upwards against the force of gravity into the head space, where it leaves it via an outlet opening which is as high as possible. On the one hand, a special cycle can be provided for the cooling oil, so that oil with special properties can be used for cooling. However, it is particularly simple and thus advantageous to use the engine oil provided for lubricating the engine also for cooling.

Another essential idea of the invention is to convey the oil collected in a common collecting space into a storage container integrated into the engine block. According to the invention, this reservoir is designed as a chamber in the engine block and not known as a separately arranged container, for example as an oil pan, arranged outside the engine block. It is advantageous if the pantry all Cylinder surrounds as a continuous space. In this case, a storage chamber for cooling oil and / or another storage chamber for lubricating oil may be provided. When using the lubricating oil as a cooling oil, a common pantry is sufficient. Advantageously, the storage chamber continues in the cylinder head, in the valve cover and in the crankcase and thus completely surrounds the cylinders.

The storage chamber integrated into the engine block and surrounding the cylinders can also be used in conventional motors with water cooling. Generally, such a storage chamber offers several advantages. First, space is saved by the inventive arrangement. Another advantage is that the surrounding the return chamber coolant jacket, which forms the storage chamber, contributes to the damping and thus the running noise and vibration of the engine can be reduced. In this way, the noise of diesel engines can be reduced to the level of gasoline engines.

In addition, such a pantry ensures that even with strong lateral accelerations, as they occur for example in extreme cornering, always sufficient coolant is present at the intake. This eliminates the risk of dry running. Even with sometimes tilted vehicles such as construction equipment and sailboats, the storage chamber according to the invention brings significant benefits. The outer surfaces of the storage chamber serve to cool the oil therein.

In order to operate this engine at high temperatures is a particularly preferred idea of the invention to manufacture the cylinder head gasket made of metal. The metal seal is also independent of the exact design of the cooling jacket is a special part of the invention. The metal seal according to the invention ensures that the engine even at temperatures above 100 ° C, where the cylinder head gaskets burn or burn out of conventional material operated can. A sealed with the metal seal oil-cooled engine, which is also equipped with the completely surrounding cooling jacket, can be at Operate temperatures of 150 ° C. At these operating temperatures, a reduction in fuel consumption of up to 25% can be achieved with a correspondingly lower exhaust emission. The more complete because of the higher temperatures combustion causes less particulate emissions, especially in diesel engines. Finally, on the one hand at the high temperature of about 140 ° C, the combustion process is significantly improved and on the other hand means the lower temperature difference, ie the lower energy dissipation, a better utilization of energy.

Advantageously, the metal gasket is formed by individual metal rings formed of wire and placed in a corresponding groove around the opening of the cylinder. In this way, each cylinder is sealed separately against the cylinder head. The metal rings can be easily and inexpensively produced and assembled by machine. When screwing the cylinder head, they are compressed and deformed. When the cylinder head is made of aluminum, the comparatively harder metal rings press into the material

Advantageously, the metal gasket is cooled. This cooling can be realized particularly easily with the sealing rings by a special wedge-shaped cooling chamber is provided in the cooling jacket, via which the oil flow to the sealing ring can be moved. It is particularly simple when the sealing rings are dimensioned so that a certain distance between the cylinder housing and the cylinder head remains, so that the oil in the intermediate space can flow around the sealing ring. In this embodiment, the cooling chamber is laterally bounded by the mutually facing end faces of the cylinder head and the cylinder block at the top and bottom and by the sealing ring.

In summary, the invention and its advantages can be described as follows: The engine consists essentially of four parts, namely the cylinder crankcase, the crankcase lower part, the cylinder head and the cylinder head cover. It differs from conventional motors in that the four components of two additional chambers enclosed on all sides are. The first inner chamber, which encloses the cooling jacket of the cylinder and the cylinder head, forms the return space for the hot cooling oil emerging in the cylinder head. This chamber opens into the oil sump. Another function of this chamber is the venting of the crankcase of passing combustion gases, which rise in this chamber upwards and are passed in the area of the cylinder head cover in the calmed state to the outside. The large surface of the chamber results in low flow velocities, which prevent turbulence and mixing of the gases with the engine oil. The running on the inner and outer chamber wall cooling oil gives off a portion of its entrained heat before it is sucked in the crankcase lower part. According to the invention, the return space completely encloses the region of the engine in which the mechanically generated noises as well as the combustion noises are produced, thereby causing an acoustic separation to the outside.

The return chamber is enclosed on all sides as an inner chamber by an outer chamber. This outer chamber serves as a storage chamber. The running over the return space in the plenum oil is sucked from there and returned to the cylinder via the cylinder head cover, which contains a Luftabscheidelabyrint. From the storage chamber, the oil is pumped in the known manner by means of a pump to the bearings and into the cooling jacket. Since the pantry encloses all sound-emitting parts, a further vibration and sound attenuation is achieved.

The entire outer surface of the engine is used for cooling and radiating the engine heat, which allows a small size of the outer radiator. By enclosing the engine chambers with their inner and outer walls, a great stability and rigidity of the entire engine design is achieved. All components can be designed with smaller wall thicknesses without affecting the torsional rigidity. From the outer supply chamber, the fresh oil required for lubrication and cooling is conveyed via a pump to the supply points. By the outer chambers surrounding the engine as a whole, The engine can also be operated in extreme inclinations without affecting the oil supply.

A major advantage of this engine is the high-temperature operation, which is possible by the elimination of water as a cooling medium. Due to the oil cooling, an average operating temperature of about 150 ° C was allowed. In order to operate the engine at this operating temperature, the classic cylinder head gasket is dispensed with and only one, inserted in a groove metal ring seal used. This metal ring is additionally oil-cooled by a circumferential gap and thus mechanically and thermally resilient. The ring seals the upper edge of the cylinder against the cylinder head. Other seals are required only for the four main body parts and the crankshaft and correspond to known silicone or shaft seals.

The high-temperature operation favors the thermal budget of the engine and leads to better combustion processes, as well as to a more effective fuel use and concomitantly to a lower pollutant emission. In conjunction with the multi-chamber system, a diesel engine achieves noise and vibration levels that are close to an Otto engine. Due to the construction described, which has a significant improvement in stiffness compared to the classic engine design, a longer life of the moving components is achieved. The oil leakage to the outside is thereby influenced favorably.

Figur 1

einen vertikalen Schnitt durch einen ölgekühlten Motorblock,

Figur 2

einen horizontalen Schnitt durch einen Zylinderkopf und

Figur 3

eine Zylinderkopfdichtung.

An embodiment of the motor according to the invention will be described below with reference to Figures 1 to 3 in more detail. Show it:

FIG. 1

a vertical section through an oil-cooled engine block,

FIG. 2

a horizontal section through a cylinder head and

FIG. 3

a cylinder head gasket.

The engine block shown in Figure 1 is known to be composed of four components. Thus, it has a central cylinder housing 1 and a cylinder head 2 covering the cylinder housing. Under the cylinder housing 1, a crankcase 3 is arranged and on the cylinder head 2, a valve cover 4 is placed. A piston 5 runs within the cylinder housing 1 in a sleeve 6 forming the cylinder and is known to be sealed against the bushing 6 by piston rings. The bushing 6 thus encloses the displacement of the piston 5. Also shown are known from conventional engines valves 7 and the connecting rod 8, which acts on the crankshaft 9.

According to the invention, the bushing 6 and thus the displacement of the piston 5 is surrounded by a coaxial annular space 10, which is acted upon by an oil flow for the purpose of cooling. The annular space 10 continues in a headspace 11, which is introduced into the cylinder head 2 and which covers the combustion chamber at the front. Head space 11 and annular space 10 form a cylinder which completely surrounds the cylinder except for the passages of the valves 7 and the injection nozzle (not shown), whereby a cylinder head gasket 12 (see FIG. 3) made of metal, which is formed as a combustion chamber seal, prevents oil from flowing out of the cooling jacket enters the combustion chamber. The oil used for the cooling is supplied in a manner to be described later by a reservoir to the bottom of the annular space 10 through an inlet opening, rises in the annular space 10 with removal of heat generated in the cylinder cylinder head 2 and enters the headspace 11 a. As can be seen from Figure 2, the annular spaces 10 of the three cylinders in this case are interconnected.

In the dome of the headspace 11, an outlet opening 13 is introduced, through which the oil escapes into the valve cover 4 along arrow A. From the valve cover 4, the oil passes from gravity into a return chamber 14 which completely surrounds the cylinder, including the annular space 10. On the walls of this return chamber 14, the oil runs down, cools and collects on the ground in a provided in the crankcase 3 plenum 15. In the plenum 15 also collects the oil that emerges from the piston cooling nozzles and the slide bearings. The return chamber 14 is composed of mutually merging chambers, which are introduced into the cylinder head 2, the cylinder housing 1 and the crankcase 3. It thus completely surrounds the cylinder and the piston drive. As can be seen from FIG. 2, the return spaces 14 of the cylinders communicate with one another and form a return space 14 surrounding the three cylinders. From the collecting space 15, the oil is pumped by means of an electrically or mechanically operated pump 16 via a return line 17 into a storage chamber 18. wherein it is first freed of residues in a filter 19 and additionally cooled by an oil cooler 20. The storage chamber 18 communicates with the annular space 10 via a line not shown in connection, so that the oil is pressed by the pressure built up by the pump 16 from the storage chamber 18 into the annular space 10. The storage chamber 18 is also housed in the engine block and in turn surrounds the entire return chamber 14. It is composed of individual compartments both in the crankcase 3, in the cylinder housing 1, in the cylinder head 2 and in the valve cover 4 on. The oil collected in the storage chamber 18 is used for both lubrication and cooling. The storage chamber 18 is sealed by seals 23, which are made in this case made of rubber, with respect to the outside space. Otherwise are annular space 10, return chamber 14 and storage chamber 18 at the joints between the components of the engine block in a conditional by the gap connection.

Via a bypass line 21, which leads from the return line 17 directly into the annular space 10 and which is switched by means of a three-way valve 22, the treated oil can be pumped directly from the plenum 15 into the annular space 10. This reduced oil volume heats up faster, so that the engine quickly reaches its operating temperature. The temperature of the engine is monitored in a known manner by temperature sensors, not shown. By the capacity of the pump 16 and the use of the bypass line 21 then the temperature of the engine can be well controlled. The continued behind the three-way valve 22 return line 17 opens in an inlet 26 in the cylinder head. From the outside, the oil to the system via an inlet 27 can be fed.

The operating temperature can be adjusted in the engine according to the invention so that it goes far beyond 100 ° C and can reach about 150 °. This is possible through the use of metal gaskets for sealing between cylinder head and cylinder. In this case, the metal gasket is a sealing ring 12 (Figure 3), which is inserted into a corresponding cylinder bore surrounding annular groove 24 in the abutting surface of the cylinder housing 1. The sealing ring is acted upon directly by the screwed cylinder head 2 squeezing and thereby deformed. In the case of a cylinder head made of aluminum, this is pressed in at the appropriate place. In order to cool the seal 12, the cooling jacket forms a cooling chamber 25, via which the oil flow to the sealing ring 12 can be moved. The cooling chamber 25 is formed in this case by a widening of the gap between the cylinder housing 1 and the cylinder head 2.

Claims (10)

1. An internal combustion engine with an engine block which has a cylinder housing and a cylinder head covering the cylinder housing, and which has a cooling jacket through oil flows, wherein the cooling jacket has an annular space (10) that at least partially and axially surrounds the working space of a piston(5) and a head space (11), wherein the head space (11) and the annular space (10) are connected directly to each other, and wherein the oil flow enters a return flow space (14) from the cooling jacket via an outlet port (13) incorporated in the head space (11), which return flow space fully surrounds at least one cylinder (6) with the inclusion of the annular space (10), characterised in that the head space (11) almost fully covers the working space on the front side.
2. The internal combustion engine according to Claim 1, characterised in that the return flow space (14) opens in a collection space (15) arranged in the crankcase (3), wherein the oil flow runs into the collection space (15) driven by gravity.
3. The internal combustion engine according to one of Claims 2 or 3, characterised in that several return flow spaces (14) surrounding the individual cylinders (6) are connected to each other and form a common return flow space.
4. The internal combustion engine according to one of the preceding claims, characterised in that a storage chamber (18) is provided in the engine block which receives a supply of fresh oil and which at least fully surrounds a cylinder (6) and, in particular, all the cylinders.
5. The internal combustion engine according to one of the preceding claims, characterised in that the oil can be conveyed via a bypass pipe (21) from the return pipe (17) directly into the annular space (10).
6. The internal combustion engine according to one of the preceding claims, characterised in that the oil used for cooling is also used for lubricating the moving parts.
7. The internal combustion engine according to one of the preceding claims, characterised in that the cylinder head is sealed against the cylinder housing by means of a metal seal.
8. The internal combustion engine according to Claim 7, characterised in that the metal seal is a sealing ring (12), in particular an 0-ring, which rests in a groove (24) inserted in the front edge of the cylinder housing (1).
9. The internal combustion engine according to Claim 7 or 8, characterised in that the cooling jacket has a cooling chamber (25) through which the oil flow is fed to the sealing ring (12).
10. The internal combustion engine according to one of Claims 7 to 9, characterised in that the annular space (10) and the head space (11) pass flush inside one another at the point of the combustion space seal or cylinder head seal (12), and form a closed cooling jacket enclosing the working space of the cylinder.

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