The arrangement related to an internal combustion engine has two motor units arranged in an engine block, in which the cylinder pertaining to each motor unit is provided with a rotatable piston arrangement, the two motor units being lat- erally oriented in relation to each other and co-ordinated with a common axis of rotation.

The present invention is applicable both to compression of a fuel/air mix- ture and when only a quantity of air is to be compressed, wherein direction injec- tion is to provide the desired mixture of fuel and air.

Background art Many different embodiments of arrangements related to internal combus- tion engines of the type described in the introduction, are already known.

As regards its structure in principle, the present invention is based on a "Wankel engine"in which an engine block is assigned two motor units and where the cylinder pertaining to each motor is provided with a piston arrangement ro- tatable in the cylinder.

The following patent publications also belong to the previous state of the art :<BR> DE-A1-4 115 194 This patent publication relates to a system comprising a piston rotating about a shaft, which shaft also constitutes the centre of a circular cylinder in which the piston is permitted to rotate.

The shape of the piston deviates from a circular line or a curved upper surface serving as a cam disc.

The tip of a tongue or wing pivotably attached via a rotating shaft abuts and runs against this cam disc shape and the rest of the outer surface of the pis-

ton.

The rotating shaft must be placed outside the defining surface of the cir- cular cylinder in order to be able to offer an out-of-the-way position for the tongue or wing upon rotation of the piston.

The tongue defines two different spaces between the piston and the cyl- inder, these spaces being expanded and compressed by the rotary movement of the piston.

In Figure 11 of the drawings a first rotor 1 functions as motor part and a second rotor 3 as compression part.

The rotor 1 turns away from the tip of the blocking part or wing 2 which must be able to move to a position 4 entirely outside the circular surface of the cylinder.

As long as the compression stroke is in progress the rotor 1 cannot per- form any work.

Motor specifically it is a question of the motor, turning in the direction of the arrow, being designed to create a suction through the opening 5.

The combustion mixture drawn in is displaced by the rotor 3 and is then carried to the combustion chamber 4 in compressed state.

After the combustion the rotor changes to the work period. The exhaust gases produced during the expansion are fed out via an opening.

US-A-5 373 819 This shows a rotating piston (6) arranged turnable about an axis of rota- tion (C), able to offer rotation within a cylinder (1) having circular cross section and with its central point (O) displaced somewhat (e) in relation to an axis of rotation for the piston.

The cylinder (1) has three chambers (2), each with cylindrical surfaces (3), which co-operate with the piston (6).

The piston (6) has two partly cylindrical surfaces connected by means of connecting surfaces (8).

The surface of this piston (6) is continuously or constantly supported by three rolls (5) assigned to said cylinder (1).

DE-A1-3 333 586 Here an arrangement is shown and described that utilises two piston cyl- inder arrangements having pistons, with cylindrical cross section, placed eccentri- cally in circular cylinders in order to produce a rotary movement inside the cylinder and, via spring-influenced sealing plates, be able to define two spaces that are expanded and compressed upon rotation of the piston.

Description of the present invention Technical problems Taking into consideration that the technical deliberations an expert in the relevant technical field must perform to be able to offer a solution to one or more technical problems include initially a necessary insight into the measures and/or the sequence of measures to be taken, as well as a necessary choice of the means required, the following technical problems are no doubt relevant in devel- oping the present invention.

Taking into consideration the previous state of the art as described above it would appear to be a technical problem, using simple means and measures, to create an arrangement related to an internal combustion engine in which each cyl- inder is assigned a circular cross section and in which the rotating piston ar- rangement to a great extent makes use of cylindrical piston units.

A technical problem is also involved in being able to recognise the signifi- cance of and advantages associated with being able to co-ordinate two motor units oriented side by side so that a first motor unit can be designed for compres- sion of a fuel/air mixture (or only compression of air) while a space intended for ignition is designed to extend directly from one motor unit over to the other motor unit, in which latter unit the working stroke is developed.

A technical problem is also involved in being able to recognise the signifi- cance of and advantages associated with permitting a first piston unit to be de- signed to take up half, or substantially half, the volume of the cylinder and to be rotatable about an axis of rotation oriented to coincide with the central axis of the cylinder.

A technical problem is also involved in being able to recognise the signifi- cance of and advantages associated with permitting a second piston unit to dis- play a cross section in the form of a segment of a circle and to take up a volume

of the cylinder corresponding to the circle segment and piston thickness, said pis- ton unit being assigned a smaller radius than said first piston unit and having an axis of rotation laterally displaced to the central axis of the cylinder.

A technical problem is also involved in being able to recognise the signifi- cance of and advantages associated with permitting a means connected to the first piston unit and to the second piston unit to be U-shaped with the shanks de- signed for co-operation with recesses in the first piston unit.

A technical problem is also involved in being able to recognise the signifi- cance of and advantages associated with permitting said means to display a flat surface abutting the second piston unit for a sliding function.

A technical problem is also involved in being able to recognise the signifi- cance of and advantages associated with permitting a first and a second piston unit assigned to one motor unit to be almost identical to a first and a second pis- ton unit assigned to the second motor unit.

It must then also be considered a technical problem, with identical first and second piston units included in both the motor units, to be able to realise the significance of and advantages associated with permitting first and second piston units, assigned to one motor unit and first and second piston units assigned to the second motor unit to be phase-displaced 180° in relation to each other.

A technical problem is also involved in being able to recognise the signifi- cance of and advantages associated with permitting one motor unit, with its cylin- der and piston arrangement having two piston units, to be chosen having a larger volume than the other.

A technical problem is also involved in being able to recognise the signifi- cance of and advantages associated with permitting the working stroke to act against the surface section assigned to the first piston unit, situated between the cylinder wall and one shank of the connecting means.

Solution The point of departure of the present invention is thus an arrangement re- lated to an internal combustion engine having at least two motor units arranged in an engine block, in which the cylinder pertaining to each motor is provided with a piston arrangement rotatable in the cylinder, the two motor units being laterally oriented in relation to each other and co-ordinated with a common axis of rotation.

In order to solve one or more of the technical problems described above in such an arrangement related to an internal combustion engine, the present in- vention proposes that a first motor unit be designed for compression of a fuel/air mixture and/or compression of just air, and that a space intended for ignition be designed to extend directly from one motor unit to the other motor unit, in which latter motor unit the working stroke is to be developed.

In accordance with proposed embodiments falling within the scope of the inventive concept a first piston unit shall be designed to take up half, or substan- tially half, the volume of the cylinder and to be rotatable about an axis of rotation oriented to coincide with the central axis of the cylinder.

The invention also advocates that a second piston unit shall be designed to display a cross section in the form of a segment of a circle and to take up a volume of the cylinder corresponding to the circle segment and piston thickness, said piston unit being assigned a smaller radius than said first piston unit and hav- ing an axis of rotation laterally displaced to the central axis of the cylinder.

The use is also advocated of a means connected to the first piston unit and to the second piston unit, which means is U-shaped with the shanks of the U- shaped means co-operating with recesses in the first piston unit.

Said U-shaped connecting means shall display a flat surface abutting the second piston unit.

The present invention also proposes that a first and a second piston unit assigned to one motor unit, shall be almost identical in cross section to a first and a second piston unit assigned to the second motor unit, but that said piston units shall be phase-displaced 180° in relation to each other.

The invention also advocates permitting one motor unit to be chosen hav- ing a larger cylinder volume than the other.

The working stroke acts against a surface section assigned to the first pis- ton unit in the second motor unit, this surface being situated between the cylinder wall and one shank of the connecting means at the start of a working stroke.

Advantages The main advantages that may be deemed characteristic for an arrange- ment related to an internal combustion engine in accordance with the present in- vention are thus that the potential is created for a simple design of the individual

piston arrangements and the piston units included, in combination with a simple design of the cylinders pertaining to each motor unit.

The use of two piston units, each in its own cylinder, also results in a suit- able solution to previously troublesome sealing problems.

The main feature of an arrangement related to an internal combustion en- gine in accordance with the present invention is defined in the characterizing part of the appended claim 1.

Brief description of the drawings An arrangement related to an internal combustion engine designed to dis- play the significant features associated with the present invention will now be de- scribed in more detail, by way of example, with reference to the accompanying drawings in which Figure 1 shows a side view, partly in section, of an arrangement related to an internal combustion engine, having two motor units arranged in an engine block, Figure 2 shows a side view of the arrangement illustrated in fig. 1, Figure 3 shows another side view of the arrangement illustrated in fig. 1, Figs. 4,5 and 6 show only two end views and a side view of a first piston unit, Figure 7 shows two different views of a means connecting two piston units, Figs. 8,9 and 10 show only two end views and a side view of a second piston unit, Figure 11 shows two different views of a means connecting two piston units, Figure 12 shows two different views of a toothed wheel co-ordinating the movements of the piston units, Figure 13 shows a side view, partly in section, of an arrangement as shown in fig. 1 during a working stroke and an exhausting se- quence, Figure 14 shows an exhausting sequence for the arrangement as illus- trated in Figure 13, and Figure 15 shows the co-operation of the two piston units during one revolu- tion for a first motor unit A and a second motor unit B connected thereto via an axis of rotation.

Description of preferred embodiment To start with it is pointed out that in the following description of a currently proposed embodiment displaying the significant features associated with the in- vention, and clarified in the accompanying drawings, we have selected terms and a special terminology with the prime aim of clarifying the inventive concept.

However, it should be observed, that expressions chosen here shall not be considered as limiting the invention only to the terms used and chosen here, but it is understood that each such term selected shall be interpreted to cover all technical equivalents that function in the same, or substantially the same, way to achieve the same, or substantially the same, purpose and/or technical effect.

Figure 1 of the accompanying drawings shows a side view, in section, of an arrangement 1 related to an internal combustion engine in accordance with the present invention.

The arrangement 1 operates in accordance with the two-stroke principle, an ignition sequence appearing at each revolution of a piston arrangement, hav- ing two motor units A, B arranged in an engine block 2, where the cylinder for each motor unit, designated AC for the cylinder in the motor unit A and BC for that in the second motor unit B, is provided with a piston arrangement rotatable in the cylinder and comprising two piston units (A1 ; B1). The two motor units A, B are laterally oriented to each other and co-ordinated with a common axis of rotation designated C.

Figure 1 also indicates the presence of two additional axes of rotation D and E, respectively, which will be described in more detail in the following.

It can also be ascertained that a first piston unit A1 and a second piston unit A2, assigned to one motor unit A, are identical to a first piston unit B1 and a second piston unit B2, assigned to the second motor unit B. However, the first pis- ton unit A1, assigned to the first motor unit A, and the first piston unit B1, as- signed to the second motor unit B, are phase-displaced 180° in relation to each other in relation to said axis of rotation C.

Since the motor units A and B are substantially identical, the following de- scription will refer primarily to the first motor unit A.

Inlet and outlet ports are connected to the cylinders AC and BC, and these are situated in the upper motor pedestal.

Referring to fig. 2, thus, it can be seen that the axis of rotation C for the

driving shaft 3 is surrounded by a toothed wheel 4 and that the axis of rotation D for a shaft pertaining to the second piston unit A2 and B2, respectively, is as- signed a toothed wheel 5.

A smaller toothed wheel 6 is arranged to allow co-ordination of the speed of rotation and directions of rotation for said toothed wheels 4,5, and thus the axes of rotation C and D.

The toothed wheel 6 is assigned an axis of rotation F.

Figure 3 shows the arrangement 1 in a different projection for the position illustrated in fig. 1, where the first piston unit A1 and the second piston unit A2 are separated by a connecting means A3.

Figures 4,5 and 6 show three different projections of the first piston unit A1 for the first motor unit A, and the first piston unit B1 for the second motor unit B, using one and the same shaft 3 to which the toothed wheel 4 is connected.

Figure 7 shows two different projections of a means A3 connecting the piston units A1 and A2. The means, seen from the side, is substantially U-shaped, the shanks being designed for co-operation with recesses in the first piston unit A1.

The connecting means 70 has parallel shanks 71,. 72 and an intermediate part 73, the surface part 74 of which is flat and arranged for sliding co-operation with a flat part on the second piston unit A2.

Figures 8,9 and 10 show three different projections of the second piston arranged in equivalent manner, with the piston units A2, B2 and the toothed wheel 5 rotatable about an axis of rotation D.

Figure 11 shows two different projections of a means 110 connecting the first piston unit B1 with the second piston B2, the shanks 111,112 of the connect- ing means being joined with the aid of an intermediate piece 113 having a flat sur- face 114 designed for sliding co-operation with a flat surface on the other piston unit.

Figure 12 shows two different projections of the driver 6 in the form of a toothed wheel enabling synchronisation of the co-ordinated rotary movement of the toothed wheels 4,5.

The toothed wheel 6 rotates about an axis of rotation F.

Figure 14 shows an exhausting sequence, and also reveals the mutual orientation of the piston units A1 and A2, and the placing of the connecting means

A3.

The invention is based on a first motor unit A being designed for com- pression of a fuel/air mixture, or compression of air, and on a space for ignition being designed to extend from one motor unit A to the other motor unit B, the working stroke being developed in the latter unit.

The first piston unit A1, shown in fig. 14, is designed to take up half, or substantially half, the volume of the cylinder and is rotatable about an axis of rota- tion C. The semicircular surface facing the cylinder will thus rotate about the cylin- der surface except in the upper position where a number of ports are located.

The axis of rotation C is thus oriented to coincide with a central axis as- signed to the cylinder.

A second piston unit A2 is designed with a cross section in the form of a segment of a circle, less than semicircular, and takes up a volume of the cylinder corresponding to a circle segment and the piston thickness, said piston unit A2 being assigned a smaller radius than said first piston unit A1 and having an axis of rotation D laterally displaced, upwards towards the ports, in relation to the central axis C assigned to the cylinder, as shown in fig. 14.

The means A3 connecting the first piston unit A1 and to the second piston unit A2 is U-shaped, the shanks being designed for co-operation with recesses in the first piston unit.

Said means A is provided with a flat surface to abut the second piston unit A2.

Figure 13 shows that the motor unit A is chosen with a larger cylinder vol- ume than the second motor unit B.

The working stroke operates against the surface section A1 a assigned to the first piston unit A1, this surface being located between the cylinder wall and one shank of the connecting means A3.

Figure 15 illustrates the relationship of the first piston unit A1 and the sec- ond piston unit A2 during one revolution, as well as the mutual position of the pis- ton unit B1 pertaining to the second motor unit B and the second piston unit B2.

The sequences are more clearly described through the positions a, b... h and show a turning movement of 45° between each position, such as a and b.

Thus the position A, b illustrates the compression and suction phase, which continues through positions A, c and A, d.

Position A, e shows the mutual position at ignition.

Similarly, position B, e shows the ignition generated in the second motor unit B and position B, f the exhaustion and working stroke.

This also continues through positions B, g and B, h.

The invention is naturally not limited to the embodiment described above by way of example. It may pass through modifications within the scope of the in- ventive concept illustrated in the appended claims.