WO2001077512A1

WO2001077512A1 - Internal combustion engine comprising cylinders arranged in a narrow v

Info

Publication number: WO2001077512A1
Application number: PCT/AT2001/000105
Authority: WO
Inventors: Tomas Visek
Original assignee: Engineering Center Steyr Gmbh
Priority date: 2000-04-11
Filing date: 2001-04-11
Publication date: 2001-10-18
Also published as: EP1146219A1

Abstract

The invention relates to a multi-cylinder internal combustion engine, whose cylinder walls (4) are arranged in two rows inclined towards each other in a single engine block (1, 1', 1'). Said engine has a cylinder head (3) that is formed as one piece with the engine block (1, 1', 1') and that comprises at least one camshaft (20). In said engine, the bases of the cylinders (5) are fixed so that they lie perpendicular to the cylinder axes (2', 2') and the main bearings (10), using bolts that are inclined towards each another (13', 13'). All intake channels (25, 26) lead from one side and all exhaust channels (36, 37) are directed towards the opposing side. The intake channels (25, 26) and the exhaust channels (36, 37) are arranged according to the same geometric configuration in all cylinders. This ensures optimum cooling and identical combustion conditions in all cylinders.

Description

COMBUSTION ENGINE WITH CYLINDERS IN NARROW V-ARRANGEMENT

The invention relates to a multi-cylinder internal combustion engine, consisting of a single cylinder block with cylinder bores arranged in two inclined rows, a common crankshaft mounted in base bearings, and at least one overhead camshaft arranged in a cylinder head.

Engines with cylinders in a narrow V arrangement were built by LANCIA as early as the 1950s (see BUSSIEN: Automobiltechnisches Handbuch, 17th edition, 1953, part 2, pages 48.94) and became known again through the VR6 engine from Volkswagen. They generally have the advantage of a small footprint in terms of length and width, and for a given number of cylinders even a much smaller footprint. This is of great importance in the transverse installation of the engine in motor vehicles that is common today. Compared to real V-engines, they also have the advantage of getting by with a common cylinder head and thus with a single cylinder head gasket. A disadvantage of engines with cylinders in a narrow V arrangement is the difficult gas flow in the cylinder head - especially if one side of the engine is the intake side and the other exhaust side. The same combustion conditions in all cylinders are very difficult to achieve because the geometrical constellation of intake ports, valves, injection nozzles and, if necessary, swirl direction, is different in both cylinder rows. The flow of cooling water is even more difficult. The tight packing of the cylinders in two rows requires a higher energy density, so more heat can be removed from a certain block volume.

Apart from the more difficult water flow in the cylinder block, the passages from the cylinder block into the cylinder head are a bad bottleneck. Due to the tight packing of the cylinders, the cylinder head screws and their screw-in plaster, which extends far into the depth for better force transmission, are only a short distance from each other, so that only very small cross-sections are available for the passage of cooling water. The cylinder head screws on the inside of the cylinder block are a particular problem. The forces introduced by them load the cylinder block on one side and flow into the cylinder liners, which leads to an impairment of the roundness of the cylinder bores. In addition, the cylinder head screws drastically restrict the freedom in the already difficult design of the gas channels and the arrangement of the organs that start the combustion (injection nozzle or spark plug).

However, the advantage of the common cylinder head with a single flat mating surface between the cylinder block and cylinder head also harbors a serious problem in modern engines with high compression, special combustion processes (stratified charge) or fuel injection Disadvantage in itself. All the more so since minimizing fuel consumption and pollutant emissions play a major role today. The inclined cylinder axes and the common flat mating surface force an unsymmetrical design of the combustion chamber. However, 5 special combustion processes (gas supply with swirl, stratified charge, injection) and high compression ratios can only be achieved with losses in consumption and emission behavior. This is particularly true for diesel engines. In addition, the inclined cylinder axis requires pistons with an inclined bottom, which is static, dynamic and thermally unfavorable. The sloping piston crown forces the top piston ring to lie low, which affects the emission behavior

From DE 29 22 726 A a prechamber diesel engine in a narrow V arrangement is known, in which the V angle of the cylinders, presumably from the

15 reasons above, is particularly small. As a result, the motor is not shortened to the extent possible at a somewhat larger V-angle. The asymmetrical shape of the piston and the central arrangement of the prechamber can be seen for reasons of thermosymmetry. On a version for engines working according to the direct injection method, in particular diesel

20 motors with the given design restrictions is unthinkable.

Another diesel engine with a narrow cylinder arrangement is known from the magazine article "Six-cylinder engines with a small V-angle" (MTZ 25 51 (1990), page 415 and pictures 12, 15). The cross-flow arrangement requires a symmetrical arrangement of the injection nozzles with the engine center plane (in contrast to the center plane of the cylinder rows) and thus very different combustion conditions. The cylinder head screws hinder the design of the gas routing channels with the same transverse the course of the cut, which is particularly important for the intake ducts. It is aggravating that diesel engines with direct injection need an inlet flow with swirl.

The aim of the invention is to design a generic motor in such a way that the disadvantages mentioned are avoided. With the smallest installation dimensions of the engine, it should be possible to optimally design the combustion chambers, to ensure adequate cooling and to carry out the gas flow and fuel supply in such a way that the same combustion conditions prevail in all cylinders.

In principle, it is already known in the case of diesel engines in series construction, for example from AT-PS 389 740, to design the cylinder block and cylinder head in one piece, but the contribution that this measure can make in conjunction with other constructive measures in achieving this goal has not been made so far been recognized. It can be assumed that the need to machine the cylinder bores from the crankshaft side made the application of this so-called monoblock design to generic engines, in which the base bearings of the crankshaft are only slightly spaced, seem impossible.

According to the invention, however, the goal set is achieved by the combination of the characterizing features of claim 1. The one-piece design of the cylinder block and cylinder head has the particularly significant advantage that cylinder head screws are no longer necessary, so there is great design freedom for the gas exchange channels, the cooling channels and also the gas channels and the injection nozzle or spark plug. Large and streamlined flow paths are available for the passage of the cooling water. The cooling water jacket can extend far down over the cylinder bottoms. All in all, the omission of the cylinder head screws means that the entire cylinder block can be made with smaller wall thicknesses and thus smaller and lighter. In extreme cases, it can even be made of light metal.

By eliminating the division plane common to the two rows of cylinders, the cylinder bottoms can be designed to be axially normal, so that combustion chambers and pistons are symmetrical. This allows the combustion chambers to be optimally designed for high compression and minimal consumption and emissions. This is particularly true for diesel engines with direct injection.

The problem of machining the closely spaced cylinder bores and the small distances between the base bearings is solved in a surprisingly simple manner in that the base bearings of the crankshaft are bearing blocks bolted to the cylinder block. The processing is not hindered and the storage chairs are only screwed on after processing.

In a particularly advantageous embodiment, the bolts are aligned parallel to the axes of the cylinder bores and screwed through the bearing blocks into the cylinder block, the bolts assigned to a bearing block being inclined in opposite directions and screwed into wall parts of the cylinder block lying outside the cylinder rows (claim 2). The inclined bolts require a linear introduction of force into the cylinder block, the cylinder walls on the outside of the cylinder block and the bolts are only subjected to tension, the cylinder walls on the inside not at all. In addition, the Roundness of the cylinders is not affected. Thus, the threaded holes of the bolts assigned to a bearing bracket can also be arranged far apart, even in the outer walls, and yet the distance between their points of attack on the bearing bracket is considerably less, which means that the bending length is small.

If, in continuation of this idea, the bolts first pass through the bearing caps, then the bearing blocks and then are screwed into the cylinder block (claim 3), the bending length on the bearing caps is even smaller because of the bolts running towards one another, and they are for the latter no own bolt required. This saves overall space, weight and costs.

In an advantageous embodiment, the cylinder block is attached to an upper part of the crankcase which is made in one piece with the bearing chairs (claim 4). Thus, the bearing chairs form a component with the crankcase upper part, which results in a particularly precise mounting of the crankshaft. The cylinder block is placed on this and by means of the bolts, to which even shorter bolts can step between the bearing chairs. This creates a particularly light, simple construction that is suitable for automated assembly

All of the advantages mentioned are particularly important for a diesel engine, especially with direct injection: high compression and symmetrical combustion chamber and piston with swirl flow possible, particularly intensive heat dissipation in the vicinity of the combustion chamber. Even the production of the same combustion conditions in both cylinder rows is also possible with an internal combustion engine, the cylinder block of which leads to an intake side of the intake ports and to an exhaust exhaust ports leading to the intake side for all cylinders and can be reached if the injectors or spark plugs in both rows are inclined to the same side and if the intake ports are arranged and designed in the same geometric constellation in all cylinders (claim 5).

The injection nozzles or spark plugs inclined in the same direction in both cylinder banks together with the cross-flow arrangement of the gas channels result in identical combustion conditions in all cylinders. The arrangement of the gas channels in the sense of the same geometric constellation means, together with the one-piece design, better cooling and larger cross-sections. If it is a direct injection diesel engine, all injectors are inclined towards the intake side. As a result, the injection nozzles can be arranged in the vicinity of the swirl-related constriction of the inlet channel, where more space and the weakening of the cylinder base are the least.

Finally, it is within the scope of the invention that the end section of the longer suction line and the end section of the shorter suction line (26) have the same shape. (Claim 6). The freedom of design given by the one-piece construction makes it easier to accommodate the relatively large pump nozzle units. Due to their inclination in the same direction, this means a larger number of identical parts for the valve train and the injection of the two cylinder banks.

The invention is explained below with the aid of illustrations of an exemplary embodiment. They represent:

FIG. 1: the subject of the invention in cross section,

Figure 2: a schematic section according to II-II in Fig. 1, enlarged. The engine block 1 shown in section in FIG. 1 in the manner customary for V-engines is a single casting and consists of a first 1 'and a second 1 "cylinder row with cylinder axes 2', 2" and a head part 3 integral therewith is therefore a motor in the so-called "monoblock" design, in the present exemplary embodiment a four- or six-cylinder engine with an angle of up to 20 ° between the cylinder rows 1 'and 1 ".

The engine block 1 consists of cylinder walls 4, each with a cylinder base 5 normal to the cylinder axis 2 and the block walls 6 forming the outer contour of the engine block 1. Gas guide ducts 7, in each case an intake duct and an outlet duct, are formed over the cylinder base 5. Around these channels 7 and between the cylinder walls 4 and the block walls 6, a cooling water chamber 8 is thus formed, which surrounds the gas guide channels 7 and the cylinder walls 4 without constrictions far down. At its lower end, the engine block 1 has a mating surface 9 to which the base bearings 10 connect. These each consist of a bearing bracket 11 and a bearing cap 12. The base bearings, the number and arrangement of which depend on the circumstances, are designed here in one piece with the crankcase upper part 19.

Bearing cover 12 and bearing bracket 11 are penetrated on both sides by bolts 13 (13 ', 13 ") which are screwed into blind bores 14 in the block walls 6. The bolts 13', 13" are inclined to one another by the same angle as the cylinder axes 2 ', 2 ". The tensile force introduced by them into the cylinder block 1 thus acts precisely in the direction of the block walls parallel to the axis. Due to the inclined arrangement, the ends of the bolts 13 ', 13" screwed into the blind bores 14 are so wide apart from each other so that they can be screwed into the block walls. No bending moments are generated. Nevertheless, their force application points on the bearing bracket are less far apart and on the bearing cap (the bolt heads 15 ', 15 ") are much less apart. This results in short bending lengths for the bearing caps. The bolts can thus be guided very close to the crankshaft 16. At the Crankshaft 16 engages pistons 18 in the usual way via connecting rods 19. The pistons 18 again have axially normal piston heads, here with the combustion troughs customary in direct injection diesel engines in other words: the engine block is connected by means of the bolts 13 ', 13 "to the crankcase upper part 19, which also forms the bearing seats.

In the head part 3 of the engine block, two camshafts 20 ', 20 "are arranged here, which act on rocker arms 21 on pump nozzle units 31 and on rocker arms 24 on gas exchange valves 23. For the same combustion conditions in both rows of cylinders, the axes 22', 22" of the pump nozzle units to the cylinder axes 2 ', 2 "by the same angle in the same direction. In the case of a gasoline engine, the spark plugs are arranged in the manner described. In both cases, identical geometric constellations and thus identical combustion conditions are created in the cylinders of the two rows of cylinders.

In the head part 3, between the cooling ducts (not individually identified), an inlet duct 25 to a cylinder of the first row 1 'and an inlet duct 26 to a cylinder of the second row 2 "can be seen Exhaust manifold 28 screwed. As a result, the inlet ducts 25, 26 and also the outlet ducts 36, 37 for the cylinders of the two rows are of different lengths. The many other details in this section are not described further because they are familiar to the engine builder.

In FIG. 2, the gas exchange channels of an embodiment as a diesel engine with direct injection are shown in greatly simplified form for cylinders belonging to two different rows, with 30 the longitudinal axis of the engine and 31 'or, depending on the row of cylinders, 31 "an injection nozzle The intake ducts 25, 26 of different lengths extend from the intake manifold 27 (see FIG. 1), with constrictions 29 towards the end, approximately horizontally over the cylinder bottoms 5 ', 5 "and form swirl chambers there 34, from which the combustion air flows into the respective cylinder through the valves 23 ', 23 ", which are only indicated with their center point. Thus, a rectified swirl flow is generated in the cylinders of both cylinder rows, indicated by directional arrows 35', 35". This arrangement and the constriction 29 allow the injection nozzles 31 ', 31 "to be moved relatively close to the center of the cylinder bottoms 5 and to be erected steeply; both are favorable for the course of the combustion.

The inlet duct 25 is substantially longer than the inlet duct 26 to the row of cylinders facing away from the intake manifold. In the exemplary embodiment shown, the two channels are curved in such a way that they open into the intake manifold at equal intervals. Their final tracts 40, 41 are geometrically the same, so that the same flow conditions prevail in the section which is decisive for the inflow into the combustion chamber. The exhaust ducts 36, 37 leading to the exhaust manifold 28 on the other engine side are also of different lengths and can be straight, since they naturally do not require swirl chambers. However, they can also be crooked, in any case they can be arranged at such a great distance from one another by implementing the teaching of the invention that they form cooling water spaces 39 between their walls 38, which reduces the particularly high thermal load in the area of the head in the vicinity of the outlet ducts.

Claims

1. Multi-cylinder internal combustion engine, consisting of a single cylinder block (1, 1 ', 1 ") with arranged in two mutually inclined rows of cylinder walls (4), a common crankshaft (16) mounted in base bearings (10), and at least one in a cylinder head (3) arranged overhead camshaft (20), characterized in that a) the cylinder head (3) with the cylinder block (1, 1 ', 1 ") is integrally formed, b) the cylinder walls (4) in normal to their axes ( 2 ', 2 ") lying floors (5) end, c) the base bearings (10) of the crankshaft (16) by means of bolts (13, 13', 13") bolted to the cylinder block (1, 1 ', 1 ") bearing seats (11) are.

2. Multi-cylinder internal combustion engine according to claim 1, characterized in that the bolts (13 ', 13 ") are aligned parallel to the axes (2', 2") of the cylinder walls (4) and through the bearing blocks (11) into the cylinder block ( 1) are screwed in, the bolts (13 ', 13 ") assigned to a bearing bracket (1 1) being inclined in opposite directions and screwed into the block walls (6) of the cylinder block (1).

3. Multi-cylinder internal combustion engine according to claim 2, characterized in that the bolts (13 ', 13 ") in sequence first pass through the bearing caps (12), then the bearing blocks (11) and then are screwed into the cylinder block (1).

4. Multi-cylinder internal combustion engine according to claim 1, characterized in that the cylinder block (1) on a crankcase upper part (19) is attached, which is made in one piece with the bearing chairs (1 1).

5. Multi-cylinder internal combustion engine according to claim 1, the cylinder block has inlet channels leading to an inlet side and outlet channels leading to an outlet side for all cylinders and injection nozzles or spark plugs, characterized in that the injection nozzles or spark plugs (31 ', 31 ") are in the same manner in both rows Side are inclined and that the inlet channels (25, 26) are arranged and designed in the same geometric constellation in all cylinders.

6. Multi-cylinder internal combustion engine according to claim 5, characterized in that the end section (40) of the intake line (25) and the end section (41) of the intake line (26) are of identical shape.