WO2013110661A2 - Assembly, in particular internal combustion engine or compressor - Google Patents

Description

 Aggregate, in particular internal combustion engine or compressor

The invention relates to an aggregate, in particular an internal combustion engine or compressor, with a housing in which a first piston having a first end surface and at least a second piston having a second end surface are arranged, wherein the first piston and the second piston alternately with limited working stroke towards and away from each other, wherein between the first end face and the second end face a working chamber for a working medium is present, which decreases and increases due to the movements of the first and the at least one second piston alternately, wherein the first and the at least a second piston are arranged in a piston cage, which is accommodated in the housing.

Such an aggregate is known from WO 201 1/147492 A2.

The unit according to the present invention may be formed in basic construction as an internal combustion engine or compressor. In further embodiments of the unit according to the invention this can be supplemented by an electromotive part as a hybrid motor or as a power generator, especially in applications be formed in a vehicle as a so-called "range extender". However, the invention is not limited to these examples.

The known from the document WO 201 1/147492 A2 mentioned above may be designed as a hybrid engine, power generator or compressor and has correspondingly a piston motor part and an electromotive part. The piston motor part of the known aggregate, to which the present invention relates, has four pistons arranged in a spherical housing. Two pistons each define between their mutually facing end faces a working chamber for a working medium, so that a total of two working chambers are formed by the four pistons. Each forming a common working chamber two pistons lead to each other and directed away from each other movements, by which the associated working chamber is alternately reduced and enlarged.

In the case of the embodiment of the unit as an internal combustion engine, a fuel-air mixture is sucked in as a working medium in the two working chambers, compressed, ignited, expanded and ejected again.

In the case of the embodiment of the unit as a compressor, a gas, in particular air, is sucked in as a working medium in the two working chambers, compressed and ejected again in the compressed state.

In the known unit, the four pistons are arranged in a common piston cage. Two pistons each with their end surfaces defining the respective working chamber are received in a receptacle formed in the interior of the piston cage in which the end sections of the pistons adjoining the respective end surface are guided gas-tight. In order to allow the piston to be fitted in the piston cage, the piston cage is composed of two halves. In the assembled state of the piston cage, the respective inner wall of the receptacles, in which the pistons are guided in a gastight manner with their end sections, forms the respective circumferential wall of the respective working chamber. In the known unit, the piston guides are thus integrated directly into the piston cage. The construction of the piston engine part of the known unit has certain disadvantages due to the integration of the piston guides in the piston cage.

A disadvantage may be seen in the fact that the incorporation or forming of the recordings forming the piston guides in the piston cage with the required high precision is difficult. A high precision or dimensional accuracy is required so that the piston seals over the entire stroke of the piston sealingly abut the piston guide wall. In addition, leakage problems in the area of the working chambers may arise due to the division of the piston cage into two parts, since the pitch of the piston cage is also present in the region of the working chambers.

Another disadvantage can be seen in the fact that the cooling and lubrication of the piston is not optimal at least in its adjacent to the respective working chamber area, because the piston cage must be performed in the piston cage integrated into the piston guides with fully closed wall. The heat dissipation through the piston cage wall is not always sufficient for adequate cooling of the pistons.

A still further disadvantage is that due to the integration of the piston guides in the piston cage for the piston guides and the piston cage without high costs no different materials can be used, since the piston cage is formed in one piece with the exception of its division in two halves. Incidentally, the use of different materials for the piston guides and the piston cage, however, may be advantageous in terms of manufacturing costs and wear resistance.

By incorporating the piston guides in the material of the piston cage is further disadvantageous to replace the entire piston cage of the known unit at a wear of the piston guides, which is associated with correspondingly higher costs. Against this background, the present invention has the object, a unit of the type mentioned in such a way that the above-mentioned disadvantages are at least partially avoided.

According to the invention this object is achieved in terms of the aforementioned aggregate, characterized in that in the piston cage at least one separable from the piston cage piston guide sleeve is disposed relative to the piston cage fixed in position in this, wherein a respective to the first end surface or connected to the second end surface end portion of the first and the at least one second piston is gas-tightly guided on an inner wall of the piston guide sleeve, so that the inner wall of the piston guide sleeve together with the first and the second end surface defines the working chamber, wherein on the inner wall only at least one at sealing gasket disposed on the first piston and the second piston.

In the unit according to the invention, the at least two pistons are no longer received directly in a piston cage in the inner wall incorporated piston guide, but in a piston cage arranged in the piston guide sleeve, which is fixedly connected to the piston cage, but this is separable. Seen from the inside out, the at least two pistons are thus at least partially disposed in the piston guide sleeve, which in turn is arranged in the piston cage. The separate embodiment of the piston guide in the form of a piston guide sleeve has the advantage that the piston guide sleeve can be made of a different material than the piston cage. The piston guide sleeve can be made of a particularly abrasion-resistant material, wherein the piston guide sleeve can be provided on the inside if necessary with a coating device. The piston cage may, for example, be made of a high-quality steel, titanium or cast aluminum, while the piston guide sleeve can be made of an aluminum alloy with a Nikasil coating, titanium sintered metal, magnesium or ceramic sinter. The piston guide sleeve can be made particularly thin-walled, which significantly improves the heat dissipation of the piston in the working chamber. Another advantage is that the piston cage, since he no longer has to ensure the gas tightness in the working chambers, at least in the area of the piston guide sleeve with large area Openings can be provided, whereby the piston guide sleeve is on the outside very well accessible for a lubricant / coolant. The cooling and lubrication of the piston engine part of the unit according to the invention is improved in this way. Yet another advantage of the unit according to the invention is that the piston guide sleeve can be replaced when worn, without having to replace the entire piston cage. In addition, the piston guide sleeve with the required for the gas-tight guidance of the piston high precision can be made easier than when the piston guides must be incorporated into the inner wall of the piston cage with this precision. As a result, the production cost and thus the production cost of the unit according to the invention is reduced. The first piston and the second piston sealingly abut the inner wall of the piston guide sleeve only by means of at least one seal arranged on the first piston and the second piston. The outer walls of the first and second pistons, however, are not in direct contact with the inner wall of the piston guide sleeve. As a result, friction losses are significantly reduced.

In a preferred embodiment, the piston guide sleeve is mounted in a fixed position by positive engagement in the piston cage.

It is advantageous that for the positional fixing of the piston guide sleeve in the piston cage no additional means such as fittings or the like are required to keep the piston guide sleeve in a stable position. In addition, this assembly reduces the assembly effort when installing the piston guide sleeve in the piston cage and the piston guide sleeve can be very easy and fast to replace it with another piston guide sleeve. The positive connection is preferably realized by a positive play-free enclosure of the piston guide sleeve through the piston cage.

In a further preferred embodiment, the piston cage has individual bearings on which the piston guide sleeve is mounted, wherein the piston cage between the bearings has one or more openings, so that the piston guide sleeve in the region of the openings exposed on the outside. This measure, which has already been mentioned above, has the advantage of improved cooling of the piston guide sleeve, since the coolant (air and / or oil) can pass through the openings directly to the outside of the piston guide sleeve. This ensures efficient heat dissipation from the piston guide sleeve and thus good cooling of the piston.

Furthermore, it is preferred in this context, when the piston cage has two bearings, of which there is a first bearing at the level of a first end of the piston guide sleeve and a second bearing at the level of a second end of the piston guide sleeve, while the opening of the piston cage extends over the working chamber.

In this embodiment, the piston guide sleeve is thus preferably mounted only at its two ends in the piston cage, while the piston cage between the bearings has an opening extending over the working chamber, preferably in the direction of movement of the piston according to their limited stroke maximum extent of Working chamber extends so that coolant (air and / or oil) can reach the outside of the piston guide sleeve just where the greatest heat development prevails. In this embodiment, the cooling of the piston guide sleeve is further improved accordingly.

Preferably, a cylindrical disc-shaped projection is integrally formed on the piston guide sleeve, which is accommodated in an annular flange of the piston cage. Together with the two abovementioned two bearings, the cylindrical disc-shaped projection forms a three-point bearing of the piston guide sleeve in the piston cage.

In another related embodiment in this context, the bearings are formed as in the circumferential direction of the piston guide sleeve extending narrow webs of the piston cage on which surveys are present in which the piston guide sleeve is present, while the piston guide sleeve between the elevations of the webs outside is spaced. Due to the design of the bearing for the piston guide sleeve in the form of narrow webs the largest possible exposed area of the outer wall of the piston guide sleeve is created, whereby the cooling of the piston guide sleeve is particularly efficient. Characterized in that the piston guide sleeve but also rests on the webs only partially present surveys, while it is spaced on the outside between the elevations of the webs, a cooling of the piston guide sleeve is ensured in the region of the webs.

A further improvement of the cooling of the piston guide sleeve in the region of the webs forming the bearing of the piston cage is achieved according to a further preferred embodiment, characterized in that the elevations extend over only a portion of the width of the webs.

In a further preferred embodiment, end portions of the first piston and the second piston, which faces away from the first end face or from the second end face, project out of the piston guide sleeve.

According to this embodiment, the piston guide sleeve accommodates only the working chamber facing end portions of the two pistons, i. the piston guide sleeve has in the direction of movement of the piston only such an extent as is required for the gas-tight guidance of the piston over the maximum stroke of the two pistons. The rear end portions of the two pistons, which protrude from the piston guide sleeve can thus also be cooled very well. At the projecting out of the piston guide sleeve end portions, the two pistons may each have a running member, wherein the running members are in communication with a cam member to produce the movements of the two pistons to reduce or increase the working chamber, as will be discussed below.

In a further preferred embodiment, the piston guide sleeve is composed in its longitudinal direction of two separable parts. This embodiment of the piston guide sleeve is advantageous if, as provided in a further preferred embodiment, in the housing, a third piston and a fourth piston are present, and the first piston with the third piston and the second piston with the fourth Piston is rigidly connected. In the case of such a design of the piston as a twin piston with a rigid coupling, the two-part design of the piston guide sleeve facilitates the assembly of the piston guide sleeve to the piston.

It is further preferred if the two parts of which the piston guide sleeve is composed, are connected together at a connection point which is located outside of the working chamber.

This measure has the advantage that the piston guide sleeve has no separation point in the region of the working chamber (also seen over the maximum volume), which could give rise to leaks in the piston guide sleeve in the working chamber, can prevail in the high pressures. Although at the junction of the two piston guide sleeve parts outside the working chamber, a seal is also required, which is not exposed to such high pressures as a seal which would be arranged in the region of the working chamber.

As already mentioned, it is provided in a further preferred embodiment that in the housing, a third piston having a third end face and a fourth piston are arranged with a fourth end face, wherein between the third end face and the fourth end face a second working chamber present is, and that the third piston and the fourth piston is associated with a second piston guide sleeve.

In this embodiment, the unit according to the invention as the known aggregate on a total of four pistons, while now the piston guides are realized by the piston cage separately and separably designed piston guide sleeves. The construction of the unit according to the invention with one or two piston guide sleeves for guiding the piston is also feasible when the first piston and the at least one second piston are pivotable about a common pivot axis, in which case the piston guide sleeve with respect to the pivot axis arcuate is curved.

Further preferably, the first piston, a first running member and the at least one second piston on a second running member, wherein the first and the second running member are guided along a cam member to the movements of the first piston and the at least one second piston for the alternate Reduction and enlargement of the working chamber to produce.

It is possible in the case of the unit according to the invention that the first piston and the at least one second piston in the housing can rotate together with the piston cage to a housing-fixed axis of rotation, while the cam member is fixed in position with respect to a rotational movement about the axis of rotation, or in that the cam member can rotate in the housing about an axis of rotation fixed to the housing, while the first piston and the at least one second piston and the piston cage are fixed in position with respect to a rotational movement about the axis of rotation.

As already mentioned, the unit according to the invention can also be configured with an electromotive part, so that the unit according to the invention not only as a pure combustion engine or pure compressor, but also as a combination of internal combustion engine and electric motor, as a power generator or as an electric motor operated Compressor can be realized.

Further advantages and features will become apparent from the following description and the accompanying drawings.

It is understood that the features mentioned above and those yet to be explained not only in the combination specified in each case, but also in other combinations or alone, without departing from the scope of the present invention.

An embodiment of the invention is illustrated in the drawing and will be described with reference to this hereafter. Show it:

1 shows an aggregate in perspective view with closed housing.

Fig. 2 shows the unit in Fig. 1 in a perspective view, wherein a

 Housing half is removed;

3 is a perspective sectional view of the unit in Figure 1, wherein the cutting plane is parallel and offset from the center plane of the unit ..;

Fig. 4 is a piston engine part of the unit in Fig. 1 in perspective

 Presentation;

FIG. 5 shows the piston motor part in FIG. 4, wherein parts have been removed with respect to FIG. 4;

FIG. 6 is a perspective view of the piston motor part of FIG. 4, with pistons of the piston motor part omitted from FIG. 4 and showing a piston cage of the piston engine part in an exploded view;

FIG. 7 shows the piston engine part in FIG. 6, with a piston cage half removed; FIG.

FIG. 8 shows the piston engine part according to FIG. 7, with pistons of the piston engine part being omitted; FIG. 9 shows the piston engine part according to FIG. 8, wherein parts of piston guide sleeves of the piston engine part have been removed;

Fig. 10 is a piston cage half of the piston motor part in perspective

 Presentation and in isolation; and

1 1, the unit in Fig. 1 in a section along a plane perpendicular to the sectional plane in Fig. 3rd

In Figures 1 to 3 and 1 1 a provided with the general reference numeral 10 unit is shown. The unit 10 is configured in the embodiment shown as an internal combustion engine with an integrated electromotive part and can be used in this embodiment as a power generator and in a vehicle drive as so-called. "Range extender". Further details of the unit are shown in Fig. 4 to 10.

The unit 10 has a housing 12, which is formed essentially by two housing halves 14 and 16. The two housing halves 14 and 16 are sealed by a plurality of screws, of which in Fig. 1, a screw is provided with the reference numeral 18, secured together. In Fig. 2, a housing half 14 is removed from the other housing half 16. There are shown in the housing half 16 holes 20 into which the screws 18 (Fig. 1) for securing the two housing halves 14 and 16 engage with each other.

In the housing 12, an electromotive part 22 is arranged, will be discussed later.

In the housing 12, a piston motor part 24 is also arranged, which will be described in more detail below with particular reference also to Figures 4 to 10. According to FIGS. 3 to 5, the piston-motor part 24 has a first piston 26, a second piston 28, a third piston 30 and a fourth piston 32. The first piston 26 and the third piston 30 are rigidly connected to each other and thus form a twin piston, and likewise the second piston 28 and the fourth piston 32 are rigidly connected together to form a second twin piston.

All four pistons 26, 28, 30 and 32 are pivotable about a common pivot axis 34 with limited stroke. The pivot axis 34 is formed by a journal bearing 36.

The first piston 26 has a first end surface 38, which is shown in Fig. 3 according to the sectional view only half. The end face 38 is designed to be circular overall. The second piston 28 correspondingly has a second end surface 40 facing the first end surface 38 of the first piston 26. The third piston 30 and the fourth piston 32 have respective end surfaces 42 and 44. In Fig. 1 1, the third end face 42 of the third piston 30 is completely visible.

Between the mutually facing end surfaces 38 and 40, the piston-motor part 24 has a first working chamber 46 for a working medium, and between the end surfaces 42 and 44 corresponding to a second working chamber 48th

While the first working chamber 46 is just assuming its maximum volume in the state shown in FIG. 3, the second working chamber 48 occupies its minimum volume.

The alternating reduction and enlargement of the volume of the first working chamber 46 is effected by alternately towards each other and away from each other directed pivoting movements of the first piston 26 and the second piston 28. Accordingly, the alternate reduction and enlargement of the volume of the second working chamber 48 is effected by the pivotal movements of the third piston 30 and the fourth piston 32 alternately toward and away from each other. Due to the rigid coupling of the first piston 26 with the third piston 30 and the second piston 28 with the fourth piston 32, the volume of the first working chamber 46 increases when the volume of the second working chamber 48 decreases, and vice versa.

In both working chambers 46 and 48 is independently of each other a full cycle (suction, compression, ignition and expansion and expulsion of the working medium) instead, wherein the working fluid in the case of the configuration of the piston engine part 24 as an internal combustion engine, a fuel-air mixture is.

The pistons 26, 28, 30 and 32 not only perform pivotal movements about the pivot axis 34 during operation of the piston motor part 24, but also run in the housing 12 about a rotation axis 50 fixed to the housing. The axis of rotation 50 is to be understood here as a geometric axis. The pivoting movements of the pistons 26, 28, 30, 32 are derived from the orbital movement of the pistons 26, 28, 30, 32 about the axis of rotation 50 by the first piston 26, a first running member 52, the second piston 28, a second running member 54, the third piston 30, a third running member 56 and the fourth piston 32, a fourth running member 58 are assigned. The running members 52, 54, 56 and 58 are in the form of balls, here in the form of hollow balls. In Figures 4, 5 and 17, the running members 52, 54, 56, 58 are also shown. The running members 52, 54, 56, 58 are arranged on the end faces 38, 40, 42, 44 facing rear end portions 60, 62, 64, 66 of the pistons 26, 28, 30, 32.

The running members 52, 54, 56, 58 are guided on a cam member 68 which has a corresponding control curve with mountains and valleys, in order to derive the pivoting movements of the pistons 26, 28, 30, 32 from the rotational movement about the axis of rotation 50. The cam member 68 is fixed in position in this case with respect to a rotational movement about the axis of rotation 50.

Alternatively, however, it is also possible, the pistons 26, 28, 30, 32 with respect to a rotational movement about the axis of rotation 50 in the housing 12 in a fixed position to arrange, while then the cam member 68 rotates about the axis of rotation 50 to produce the pivoting movements of the pistons 26, 28, 30, 32.

According to Figures 4 and 5, the pistons 26, 28, 30, 32 are arranged in a piston cage 70, which is also part of the piston motor part 24. In the case that the pistons 26, 28, 30, 32 rotate in the housing 12 about the axis of rotation 50, the piston cage 70 rotates together with the pistons 26, 28, 30, 32 about the axis of rotation 50. In the event that the pistons 26, 28, 30, 32 do not revolve about the axis of rotation 50, but rather the cam member 68, the piston cage 70 is also fixed with respect to a rotational movement about the axis of rotation 50.

The piston cage 70 is composed of two piston cage halves 72 and 74. In Fig. 6, the two Kolbenkäfighälften 72 and 74 are separated from each other and shown spaced. The dividing plane, along which the piston cage 70 is divided into the two piston cage halves 72 and 74, contains the longitudinal axis (axis of rotation 50) of the piston cage 70.

4, lubricant supply rings 76 and 78 are arranged on the piston cage 70 at its longitudinal ends, and in each case a piston cage bearing ring 80 or 82 and a sensor ring 84 for the electromotive part 22 (see also Fig. 1 1). About the bearing ring 80 and 82 of the piston cage 70 is mounted in the housing 12.

The pistons 26, 28, 30, 32 are not guided directly in the piston cage 70 in terms of their pivotal movements about the pivot axis 34, but, as shown in Fig. 7, in the piston guide sleeves 86 and 88. In this case, the first piston 26th and the second piston 28 is guided in the piston guide sleeve 86, and the piston 30 and the fourth piston 32 in the piston guide sleeve 88. Fig. 7 shows only the piston cage half 74, while the other piston cage half 72 in Fig. 7 is removed.

The piston guide sleeves 86 and 88 are mounted in the piston cage 70 relative to this fixed position, as will be described below. 3, an end wall 92 of the first piston 26 adjoining the end surface 38 is gas-tightly guided on an inner wall 90 of the piston guide sleeve 86, and an end section 94 of the second piston 28 adjoining the second end surface 40 is the first piston 26 and the second piston 28 each have at least one seal 87 and 89, with only the seals 87 and 89 sealingly abut the inner wall 90 of the piston guide sleeve 86 and are in contact therewith, while the pistons 26 and 28 with their outer walls not in contact with the inner wall 90 of the piston guide sleeve 86. The pistons 26 and 28 are supported on the axle bearing 36 on the centrifugal force side, thereby avoiding that the outer walls of the pistons 26, 28 come into contact with the inner wall 90 of the piston guide sleeve 86. In the embodiment shown, the seals 87 and 89 are formed as conventional piston rings. It is understood that a plurality of (here three) seals 87 and 89 can be arranged on the pistons 26, 28 as shown.

Corresponding seals 91 and 93 are provided on the third piston 30 and 32 for sealing engagement with the inner wall 95 of the piston guide sleeve 88.

As is apparent from Fig. 3, the extension of the piston guide sleeve 86 in the pivoting movement direction of the piston 26, 28 adapted to the maximum stroke of the piston 26 and 28. Fig. 3 shows the maximum opening stroke of the piston 26 and 28. The piston guide sleeve 86 extends so far that the gas-tightness of the piston guide is ensured over the entire stroke. Together with the end surfaces 38 and 40, the inner wall 90 defines the working chamber 46 as a whole.

The same applies to the piston guide sleeve 88 in cooperation with the third piston 30 and the fourth piston 32, so that reference can be made to the description with respect to the piston guide sleeve 86.

As can be seen in particular Figures 7 and 8, the piston guide sleeves 86 and 88 an arcuate curvature, which is adapted to the pivotal movements of the pistons 26, 28 and 30, 32. According to the illustrated embodiment of the pistons 26, 28, 30, 32 with a circular cross section (perpendicular to their direction of movement), the inner wall 90 of the piston guide sleeve 86 has a circular cross-section. mige cross-sectional shape, and also has an inner wall 95 of the piston guide sleeve 88 has a circular cross section.

The piston guide sleeves 86 and 88 are held firmly in position in the piston cage 70 by positive engagement.

According to FIGS. 6 and 10, the piston cage 70 has individual bearings on which the piston guide sleeves 86, 88 are mounted. In the embodiment shown, the piston cage 70 for the piston guide sleeve 86 exactly two bearings 96, 96 'and 98, 98', in the circumferential direction of the piston guide sleeve 86 in the form of narrow webs 100, 100 ', 102, 102' radially with respect to a center 104 (which coincides with the pivot axis 34) extend. In this case, the piston guide sleeve 86 is not over the entire surface on the webs 100, 100 ', 102, 102', but the bearings 96, 96 ', 98, 98' are by on the webs 100, 100 ', 102, 102' in sections existing elevations 105 and 106 formed (corresponding elevations are also on the webs 100 ', 102' available) on which the piston guide sleeve 86 rests alone. In areas 108 and 110, respectively, between the elevations 105 and 106, the piston guide sleeve 86, however, spaced from the webs 100, 100 ', 102, 102' on the outside.

Furthermore, the elevations 105 and 106 do not extend over the entire width of the webs 100, 100 ', 102, 102', but only over part of the width of the webs 100, 100 ', 102, 102', by the elevations 105 and 106 interruptions 1 12 and 1 14 have.

For the piston guide sleeve 88, the piston cage 70 corresponding bearing 1 16, 1 16 ', 1 18, 1 18', for the description of the description of the bearings 96, 96 ', 98, 98' is referenced.

Between the bearings 96, 96 ', 98, 98' or 1 16, 1 16 'and 1 18, 1 18', the piston cage 70 large openings 120 and 122 (Fig. 10) and openings 124, 126th (Fig. 4), so that the piston guide sleeves 86, 88 in the area these apertures 120, 122, 124, 126 on the outside exposed over a large area and thus can be cooled very well.

As is apparent from Fig. 10 in conjunction with Fig. 8, are the bearings 96, 96 ', 98, 98' and 1 16, 1 16 ', 1 18, 1 18' at or at the level of ends 128, 130 of the piston guide sleeve 86 and at or at the level of ends 132, 134 of the piston guide sleeve 88. The openings 120, 124 and 122, 126, however, extend substantially over the working chambers 46 and 48, as in a comparison of Figures 10, 4 and 3 results.

As is apparent from Fig. 7, protrude the rear end portions 60, 62, 64, 66 of the piston 26, 28, 30, 32 out of the piston guide sleeves 86 and 88, so that the running members 52, 54, 56, 58 are free for the guidance of the cam member 68.

The piston guide sleeves 86 and 88 are, as shown in Fig. 4, in the assembled state of the piston cage 70 positively and securely held in the piston cage 70. The connection of the two Kolbenkäfighälften 72 and 74 via the Aufpressung the piston cage bearing ring 80, 82 and Schmiermittelzuführringe 76, 78 on annular seating surfaces 129, 131 and 133, 135 of the piston cage 70 and the central screw of the axle 36 in the piston cage 70. In addition, the Form-fitting on the piston guide sleeves 86 and 88 effected by integrally formed cylindrical or kugelkappen- shaped projections 137, 139, which are received in the interior of the annular seat surfaces 129, 131, 133, 135 fit. The cylindrically disc-shaped or kugelkappenförmi- gene lugs 137, 139 together with the bearings 96, 96 ', 98, 98' and 1 16, 1 16 ', 1 18, 1 18' each have a three-point storage of the respective Piston guide sleeve 86 and 88 in the piston cage 70, whereby a particularly secure positionally stable mounting of the piston guide sleeves 86, 88 is ensured in the ball cage.

The piston guide sleeves 86 and 88 thus need for their secure positionally stable storage in the piston cage 70 no further fastening means and are thus easily separable from this after opening the piston cage 70. As best seen in Figures 8 and 9, the piston guide sleeve 86 in its longitudinal direction of two parts 136, 138 is composed of separable. In Fig. 9, the part 138 is removed from the part 136. The gas-tight connection of the two parts 136 and 138 to each other takes place in the region of two flanges 140, 142 formed on the parts 136, 138 by means of screwing and a flat gasket between the flanges 140, 142. The separating surface formed by the flanges 140, 142 is between them the two parts 138 and 136 outside the working chamber 46th

Another provided on the part 136 flange 144 is a blind flange and serves only to balance the mass with respect to the orbital motion of the piston cage 70 and thus the piston guide sleeve 86 about the axis of rotation 50th

The piston guide sleeve 88 is divided into two parts in the same way as the piston guide sleeve 86, so that reference can be made to the relevant description of the piston guide sleeve 86.

The division of the piston guide sleeve 86 and the piston guide sleeve 88 in two parts is used for simplified assembly in the embodiment shown in which the first piston 26 and the third piston 30 and the second piston 28 and the fourth piston 32 are rigidly interconnected ,

For this purpose, the parts 136 and 138 after connection of the pistons 26, 28 with the axle bearing 36 individually pushed onto the first piston 26 and the second piston 28 and only then screwed to the flanges 140, 142 together.

Radially outward with respect to the pivot axis 34, the piston guide sleeve 86 has a surface 146 on the projection 137, which is a portion of a spherical surface. The surface 146 forms a sliding surface which sealingly slides on a housing-fixed end cover 148 (FIG. 11). Furthermore, an opening 150 for inserting a spark plug 152 (see, for example, FIGS. 1 and 11) is present in the surface 146 or the projection 137. Furthermore, a gas exchange opening is provided in the area 146. tion 153 available (see Fig. 1 1). The corresponding gas exchange opening 154 in the extension 139 of the piston guide sleeve 88 can be seen in FIG. 9. As the piston cage 70 rotates about the axis of rotation 50, the gas exchange port 153 in the surface 146 communicates alternately with a gas inlet 156 or gas outlet 158 (depending on the direction of rotation of the piston cage 70). A corresponding gas inlet and outlet are also associated with the second working chamber 48, with which the gas exchange opening 154 in the neck 139 of the piston guide sleeve 88 alternately communicates.

The piston guide sleeve 86 and the piston guide sleeve 88 are made of a material that is different from the material from which the piston cage 70 is made. Depending on the application, the piston cage 70 may consist of a high-quality steel, titanium or cast aluminum, while the piston guide sleeves 86, 88 may consist of an aluminum alloy, provided with a Nikasil coating or with a hard coat. Also conceivable is the execution of the piston guide sleeves made of a carbon fiber composite material or other suitable material, such as sintered materials.

Referring to Figs. 10 and 11, lubricant guide tubes 160, 162, 164, 166 are disposed in the piston cage halves 72 and 74 for the supply of the lubricant and coolant, which extend parallel to the longitudinal axis (rotation axis 50) but outside thereof. The lubricant guide tubes 160, 162 may be considered in the case of the design of the piston cage halves 72, 74 as castings during casting or later injected as tube sleeves. With the aid of this lubricant supply both the axle 36 and the outer sides of the piston guide sleeves 86, 88 can be supplied with lubricant and coolant.

However, it is also possible a closed, circulating air cooling of the piston engine part 24 of the unit 10th

The above electromotive part 22 annularly surrounds the piston motor part 24, so that the piston motor part 24 is arranged inside the electromotive part 22. The electromotive part 22 has, according to FIG. 2, a stator 170 with windings 172 and magnetic cores 174, wherein the stator 170 is not completely shown in FIG. 2, but it is understood that the stator 170 in the housing 12 is full about the axis of rotation 50 is present.

The electromotive part 22 further comprises a rotor 176 (see also Figures 3 and 1 1), which rotates in the housing 12 about the axis of rotation 50 together with the piston cage 70 and the piston 26, 28, 30, 32 in operation ,

The rotor 176 of the electromotive part 22 is rotatably connected to the piston cage 70, i. the rotor 176 rotates with the piston cage 70 at the same time about the axis of rotation 50. It may be provided a coupling which allows an optional decoupling or coupling of the rotor 176 from or with the piston cage 70.

Claims

claims 1 . An engine, in particular an internal combustion engine or a compressor, having a housing (12) in which a first piston (26) having a first end surface (38) and at least a second piston (28) having a second end surface (40) are arranged, the first one Piston (26) and the second piston (28) are movable alternately with limited stroke towards and away from each other, wherein between the first end face (38) and the second end face (40) is a working chamber (46) for a working medium, the is alternately reduced and enlarged due to the movements of the first and at least one second pistons (26, 28), the first and at least one second pistons (26, 28) being disposed in a piston cage (70) housed within the housing (10). 12), characterized in that in the piston cage (70) at least one of the piston cage (70) separable piston guide sleeve (86) is arranged, the relative to the piston cage (70) positionally in this gelag wherein a respective end portion (92, 94) of the first and at least one second piston (26, 28) adjoining the first end surface (38) and the second end surface (40), respectively, on an inner wall (90) of FIG Piston guide sleeve (86) is guided gas-tight, so that the inner wall (90) of the piston guide sleeve (86) together with the first and the second end face (38, 40) defines the working chamber (46), wherein on the inner wall (90) only in each case at least a seal (87, 89) arranged on the first piston (26) and the second piston (28) bears in a sealing manner. 2. Unit according to claim 1, characterized in that the piston guide sleeve (86) by positive engagement in the piston cage (70) is mounted. 3. Unit according to claim 1 or 2, characterized in that the piston cage (70) has individual bearings (96, 96 ', 98, 98') on which the piston guide sleeve (86) is mounted, wherein the piston cage (70) between the bearings (96, 96 ', 98, 98') one or more openings (120, 124), so that the piston guide sleeve (86) in the region of the openings (120, 124) exposed on the outside. 4. Unit according to claim 3, characterized in that the piston cage (70) has two bearings (96, 96 ', 98, 98'), of which a first bearing (96, 96 ') at the level of a first end (128 ) of the piston guide sleeve (86) and a second bearing (98, 98 ') at the level of a second end (130) of the piston guide sleeve (86), while the at least one opening (120, 124) of the piston cage (70) via the working chamber (46) extends. 5. Unit according to claim 3 or 4, characterized in that the bearings (96, 96 ', 98, 98') as in the circumferential direction of the piston guide sleeve (86) extending narrow webs (100, 100 ', 02, 102') of the Piston cage (70) are formed on which portions elevations (105, 106) are present, in which the piston guide sleeve (86) is present, while the piston guide sleeve (86) between the elevations (105, 106) of the webs (100, 100 ' , 02, 102 ') is spaced on the outside. 6. Unit according to claim 5, characterized in that the elevations (105, 106) extend over only a part of the width of the webs (100, 100 ', 02, 102'). 7. Unit according to one of claims 1 to 6, characterized in that from the first end face (38) and from the second end face (40) facing away from end portions (60, 62) of the first and second pistons (26, 28) the piston guide sleeve (86) protrude. 8. Unit according to one of claims 1 to 7, characterized in that the piston guide sleeve (86) is composed in its longitudinal direction of two separable parts (136, 138). 9. An assembly according to claim 8, characterized in that the two parts (136, 138) are interconnected at a connection point, which is located outside of the working chamber (46). 10. Unit according to one of claims 1 to 9, characterized in that in the housing (12) a third piston (30) having a third end face (42) and a fourth piston (32) having a fourth end face (44) are arranged wherein there is a second working chamber (48) between the third end face (42) and the fourth end face (44) and a second piston guide sleeve (88) is associated with the third piston (30) and the fourth piston (32). 1 1. Aggregate according to claim 9 or 10, characterized in that the first  Piston (26) is rigidly connected to the third piston (30), and that the second piston (28) with the fourth piston (32) is rigidly connected. 12. Unit according to one of claims 1 to 1 1, characterized in that the first piston (26) and the at least one second piston (28) about a common pivot axis (34) are pivotally movable, and that the piston guide sleeve (86) with respect Swivel axis (34) is arcuately curved. 13. Unit according to one of claims 1 to 12, characterized in that the first piston (26) has a first running member (52) and the at least one second piston (28) has a second running member (54), wherein the first and the second Running member (52, 54) along a cam member (68) are guided to generate the movements of the first piston (26) and the at least one second piston (28) for alternately reducing and enlarging the working chamber (46). 14. Unit according to claim 13, characterized in that the first piston (26) and the at least one second piston (28) in the housing (12) together with the piston cage (70) can rotate about a housing-fixed axis of rotation (50) while the cam member (68) is fixed in position with respect to a rotational movement about the axis of rotation (50). 15. An assembly according to claim 14, characterized in that the cam member (68) in the housing (12) can rotate around a housing-fixed axis of rotation (50), while rend the first piston (26) and the at least one second piston (28) and the piston cage (70) with respect to a rotational movement about the axis of rotation (50) are fixed in position. 16. Unit according to one of claims 1 to 15, characterized in that the piston cage (70) and the piston guide sleeve (86) are made of different materials.