EP0185009B1 - Internal combustion engine with a sound insulating enclosure surrounding the same - Google Patents

Description

The invention relates to an internal combustion engine with a sound-insulating capsule enclosing it and forming a lubricating oil collecting space.

Capsules of this type, so-called wet capsules, which are preferably made of sheet metal or light metal casting, form the closure of the lubricating oil chambers of the internal combustion engine to the outside, thus contain the lubricating oil sump and their walls are sprayed with oil on the inside. In internal combustion engines with a wet or dry capsule, that is to say only to reduce the noise emission, capsules often encounter difficulties in operation in that the heat accumulating in the capsule cannot be dissipated to a sufficient extent.

A cooling system for the cooling water and / or for the lubricating oil is required in all internal combustion engines, a cooler with a corresponding fan driven by the internal combustion engine itself or via an electric motor being generally provided. In order to save fuel and to limit the comparatively large space requirement for the cooling system, it is desirable to reduce it or to avoid it at all.

Another unfavorable property of internal combustion engines can also be seen in the fact that after long cooling phases at low outside temperatures, a new start is sometimes difficult or is associated with increased exhaust gas emissions and also increased fuel consumption during the warm-up process.

From DE-A-2 834 089 an internal combustion engine is known which has cladding panels fastened on both sides of the crankcase to its connecting flanges with the interposition of seals by means of screws. The cladding panels and crankcase wall form an oil container for noise insulation. Since no measures have been taken to prevent the transmission of structure-borne noise from the crankcase to the cladding panels, it is not an internal combustion engine which is enclosed by a sound-insulating capsule.

From DE-A-3 032 090 an internal combustion engine is already known, the oil pan of which is wholly or partly surrounded by a wall in the form of a heat pipe, but which is not a sound-insulating capsule for the internal combustion engine.

DE-A-3 335 983 describes an internal combustion engine in which the engine mount containing the directly structure-borne noise parts is connected to the crankcase via a plurality of structure-borne noise-isolating, force-transmitting elements, which in turn connects the engine mount to soundproof passages at both ends of the crankshaft and to encloses a long side of the cylinder head on all sides to form an oil-soaked capsule. No measures have been taken which favor starting the internal combustion engine after an extended interruption in operation.

The invention has for its object to remedy these shortcomings and to improve the internal combustion engine described at the outset so that the cooling system is reduced in size by simple means and more favorable conditions are achieved when starting after a long interruption in operation.

The invention solves this problem in that the capsule wall is at least partially formed by heat oil on the inside of the capsule wall, acted upon by spray oil, as a heat accumulator and by increasing the surface area (fins) as a heat exchanger.

Due to the arrangement of heat-storing areas on the inside of the capsule wall, heat is absorbed during normal operation by the spraying oil of the internal combustion engine, and during the machine downtime and cooling phases, the heat-storing material warmed up by the lubricating oil remains at a higher temperature for a long time and slowly releases the stored heat back to the air surrounding the internal combustion engine or to the air itself. As a result, the cooling process of the machine is much slower and a new start is made easier. The internal combustion engine also quickly returns to full operating temperature after starting, which shortens the phase of increased exhaust gas emissions and increased fuel consumption. By designing part of the capsule wall as a heat exchanger, heat can be dissipated from the internal combustion engine to the outside thereof, making it possible to thermally relieve areas of the internal combustion engine and thereby reduce the size of the cooling system.

This heat storage effect of the heat storage material can be increased if, according to the invention, the heat storage material is ribbed.

In a further embodiment of the invention, the capsule wall is provided with ribs in a manner known per se for enlarging the surface. These ribs can be arranged both on the outside of the capsule and on the inside, depending on whether they are to form the heat exchanger or to serve to enhance the heat storage effect.

It is also advantageous if a heat pipe system known per se is arranged between hot parts of the internal combustion engine and the capsule wall. Heat pipes have the property of enabling particularly intensive heat transport. By connecting hot parts of the internal combustion engine, from which the heat pipe takes heat, to the corresponding areas of the capsule wall, to which the heat pipe releases the heat again, the heat can be removed from the internal combustion engine Machine to the capsule wall designed as a memory or heat exchanger are significantly intensified.

A further embodiment of the invention consists in that the heat pipes are acted upon directly or indirectly by the cooling water and / or by the lubricating oil, and on the other hand are connected to the capsule wall. It is thus possible for the cooling of the internal combustion engine to be carried out entirely by the capsule wall and for a separate water and / or oil cooler to be dispensed with. Finally, according to the invention, the area of the capsule designed as a heat exchanger is exposed to a cooling air flow, from which the wall areas serving as heat stores are removed. This makes it possible, on the one hand, to ensure sufficient cooling of the internal combustion engine and, on the other hand, to maintain the heat to be stored for the cooling and starting phases of the machine.

The design according to the invention not only results in the described thermal advantages, but also the noise-damping effect is increased and the ribs stiffen the capsule walls, which can bring about a further improvement in soundproofing.

• Fig. 1 den Vertikalschnitt durch eine eine Brennkraftmaschine umschließende Kapsel nach der Linie I - I der Fig. 2,
• Fig. 2 die Kapsel in Seitenansicht,
• Fig. 3 eine Draufsicht bei abgenommenen Deckel bzw. Oberteil und
• Fig. 4 ein Wärmerohr im Schnitt.

In the drawing, the subject matter of the invention is shown purely schematically in one embodiment, namely show

• 1 shows the vertical section through a capsule enclosing an internal combustion engine along the line I - I of FIG. 2,
• 2 the capsule in side view,
• Fig. 3 is a plan view with the cover or upper part removed
• Fig. 4 is a heat pipe in section.

The sound-absorbing capsule surrounding the internal combustion engine 1 consists of the central capsule part 2, the capsule cover or upper part 3 and the oil pan 4, since the capsule for the internal combustion engine 1 forms the lubricating oil collecting space. One half of the capsule middle part 2 and the capsule lid or top part 3 is provided on the inside with a layer of heat-storing material 5. A ceramic mass is an example of a heat-storing material. However, it is also possible to provide the capsule wall with cavities and into the cavities water, glycerin or the like as heat-storing. Fill in material. The lubricating oil thrown around by the internal combustion engine 1 during its operation reaches the capsule walls and heats the storage material 5 there. When the machine is at a standstill, the heat in the heat storage material 5 is retained for a long time, so that the restarting of the machine is facilitated.

The other half of the capsule middle part 2 or capsule upper part 3 is provided with outer wall ribs 6 for surface enlargement, which serve to intensify the heat dissipation to the outside and thus form a heat exchanger. The ribs 6 are exposed to the cooling air flow from a fan 7, which can serve, for example, at the same time as a fan for the water cooler 8 of the internal combustion engine 1. The capsule half serving as a heat accumulator naturally has no outer ribs and is thus essentially removed from the cooling air flow of the fan 7.

According to FIG. 3, heat pipes 9, indicated by dash-dotted lines, are provided to improve the heat transport from the hot parts of the internal combustion engine 1 to the capsule wall. One of the heat pipes 9 takes the heat directly from the cooling water system and passes it on to the capsule half occupied by cooling fins 6. Therefore, the water cooler 8 can be made smaller. The oil filter head 10 is also connected to the capsule wall via heat pipes 9, a heat pipe 9 leading to the wall area of the capsule lined with the heat storage material 5 and a heat pipe from the oil filter head 10 to the wall of the capsule half serving as a heat exchanger. Particularly hot areas of the internal combustion engine 1, such as the cylinder head 11 or the exhaust line, can also be connected to the wall of one or the other capsule half.

4, a heat pipe 9 consists of a closed hollow body 12 formed of metal, which has a heating zone 13, a cooling zone 14 and a transport zone 15. A wire mesh 16 with a capillary structure is arranged in the interior of the hollow body 12; the cavity is filled with a liquid serving as a heat transfer medium. The heating zone 13 is arranged in that area of the internal combustion engine 1 from which heat is to be removed, whereas the cooling zone 14 is connected to the capsule wall. In the heating zone 13, the liquid heat transfer medium is evaporated, and steam flows through the capillary structure of the wire mesh 16 in the direction of the cooling zone 14, where it condenses and releases the heat again. The condensate is transported back to the heating zone 13 by the suction effect of the capillaries. The shape of the heat pipe 9 is arbitrary, and it is also possible to transport heat over relatively long distances. The transport zone 15 is of course shielded from the environment with heat insulation material.

Claims (6)

1. An internal combustion engine comprising a sound-insulating capsule, which encloses the engine and defines a space for collecting lubricating oil, characterized in that at least portions of the capsule wall constitute a heat accumulator owing to the provision of heat- accumulating material (5), which has been applied to the inside surface of the capsule wall and is contacted by splashed oil, and constitute a heat exchanger because their surface area has been increased (6).

2. An internal combustion engine according to claim 1, characterized in that the heat-accumulating material (5) is ribbed.

3. An internal combustion engine according to claim 1, characterized in that the capsule wall is provided in a manner known per se with ribs (6) to increase its surface area.

4. An internal combustion engine according to any of claims 1 to 3, characterized in that a heat tube system (9) is provided in a manner known per se between hot parts (10, 11) of the internal combustion engine (1) and the capsule wall.

5. An internal combustion engine according to claim 4, characterized in that the heat tubes (9) are indirectly or directly contacted by the cooling water and/or lubricating oil on one side and are joined to the capsule wall on the other side.

6. An internal combustion engine according to any of claims 1 to 5, characherized in that that portion of the capsule (2, 3, 4) which constitutes a heat exchanger is exposed to a cooling air stream, which is out of contact with the wall portions which serve as a heat accumulator.

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