AXIAL PISTON ENGINE AND METHOD FOR OPERATING AN AXIAL PISTON ENGINE

Abstract

To improve the efficiency of an axial piston engine, the invention proposes an axial piston engine with a combustion chamber which operates with two-stage combustion.

Claims

1. Method for operating an axial piston engine with continuous combustion, wherein fuel is decomposed in a first step and after said first step is brought into contact with process air for ignition and combustion in a second step, wherein the decomposition of the fuel takes place thermally by thermal energy until ignition.

2. Method according to claim 1, wherein the preparation flame is generated by a fuel/air mixture.

3. Method according to claim 2, wherein a portion of fuel which is brought into a combustion chamber or into a preparation chamber by the fuel/air mixture is less than 10% of the total quantity of fuel which is introduced into the combustion chamber.

4. Method according to claim 1, wherein the thermal energy for the decomposition is provided by a preparation flame.

5. Method according to claim 1, wherein the fuel is sprayed into the combustion chamber by a main nozzle, wherein the main nozzle is aligned coaxially to an axis of symmetry of the combustion chamber.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0052] Further advantages, objectives and properties of the present invention are described using the following description of the attached drawing, in which a first exemplary embodiment of an axial piston engine is shown by way of example.

[0053] In the drawings,

[0054] FIG. 1 schematically shows an axial piston engine in longitudinal section;

[0055] FIG. 2 schematically shows the axial piston engine according to FIG. 1 in cross section along line H-H;

[0056] FIG. 3 schematically shows an enlarged illustration of the firing channel ring of FIG. 1;

[0057] FIG. 4 schematically shows a longitudinal section through a control piston as an alternative to the control piston according to FIGS. 1 and 2; and

[0058] FIG. 5 schematically shows a cross section through the control piston according to FIG. 4 along the line V-V.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

[0059] The axial piston engine 1 shown in FIG. 1 has a combustion chamber 2 in which a fuel I air mixture can be ignited and burned. The axial piston engine 1 advantageously operates with two-stage combustion. To this end, the combustion chamber 2 has a first region 3 and a second region 4 into which the fuel and/or air can be injected. In particular in the first region in 3, a portion of combustion air of the axial piston engine 1 can be introduced, wherein in this exemplary embodiment the portion of combustion air can be set to be less than 15% of the total combustion air.

[0060] The combustion chamber 2 of the axial piston engine 1 can be divided by the two regions 3 and 4 into a preparation chamber 5 and a main combustion chamber 6.

[0061] The preparation chamber 5 has a smaller diameter than the main combustion chamber 6, wherein the preparation chamber 5 is further divided into a prechamber 7 and a main chamber 8. The prechamber 7 has a conical configuration and widens towards the main chamber 8.

[0062] There is connected to the preparation chamber 5, in particular to the prechamber 7 of the preparation chamber 5, a main nozzle 9 on one side and a preparation nozzle 10 on the other side. A fuel can be introduced into the combustion chamber 2 by means of the main nozzle 9 and the preparation nozzle 10, wherein the fuel which is injected by means of the preparation nozzle 10 is already mixed with air.

[0063] The main nozzle 9 is aligned parallel to a main combustion direction 11 in the combustion chamber 2 of the axial piston engine 1. Furthermore, the main nozzle 9 is aligned coaxially to an axis of symmetry 12 of the combustion chamber 2 which lies parallel to the main combustion direction 11 in the combustion chamber 2.

[0064] The preparation nozzle 10 is aligned at an angle 13 to the main nozzle 9. In this respect, a jet direction 14 of the preparation nozzle 10 intersects a jet direction 15 of the main nozzle 9 at an intersection point 16.

[0065] The preparation chamber 5, into which both the main nozzle 9 and the preparation nozzle 10 are oriented, opens towards the main combustion chamber 6. Fuel is injected out of the main nozzle 9 into the preparation chamber 5 without additional supply of air. The fuel is already preheated, ideally thermally decomposed, in the preparation chamber 5.

[0066] To this end, the quantity of air which corresponds to the quantity of fuel which flows through the main nozzle 9 is introduced into the main combustion chamber 6 downstream of a preparation chamber 5, for which a separate air supply 17 is provided which opens essentially into the main combustion chamber 6. To this end, the separate air supply 17 is connected to a process air supply 18, wherein a further air supply 19 can be supplied with air, which supplies a perforated rim 20 with air. The perforated rim 20 is allocated to the preparation nozzle 10 so that the fuel which is injected with the preparation nozzle 10 can additionally be injected into the prechamber 7 of the preparation chamber 5 with process air.

[0067] The combustion chamber 2, in particular the main combustion chamber 6 of the combustion chamber 2, has a ceramic assembly 21 which is air-cooled. The ceramic assembly 21 in this case comprises a ceramic combustion chamber wall 22 which is surrounded by a profiled tube 23. A cooling air chamber 24 extends around this profiled tube 23, which cooling air chamber is operatively connected to the process air supply 18 by means of a cooling air chamber supply 25.

[0068] Furthermore, the axial piston engine 1 has working cylinders 30 which are known per se (see in particular FIG. 2), in which working pistons 31 can be moved forwards and backwards.

[0069] Compressor pistons 32 of the axial piston engine 1 are driven by means of the working pistons 31, which compressor pistons can be moved correspondingly in suitable compressor cylinders 33 of the axial piston engine 1. The working pistons 31 are connected to the compressor pistons 32 in each case by means of a connection rod 34, wherein a connection rod wheel 35 is arranged in each case between the working piston 31 and the connection rod 34 and between the compressor piston 32 and the connection rod 34. A drive curved path 36 is enclosed in each case between two connection rod wheels 35, which drive curved path is guided on a drive curved path support 37. Opposite the combustion chamber 2, the axial piston engine 1 has a drive shaft 38, by means of which the power generated by the axial piston engine 1 can be output. The process air is compressed in the compressor pistons 32 in a manner which is known per se, including where applicable the injected water, which may lead to additional cooling, as a result of which however the exhaust gases can if applicable be cooled much more in a heat exchanger if the process air is to be guided to the combustion chamber 2 preheated by means of such a heat exchanger, wherein the process air can be heated or preheated by contact with other assemblies of the axial piston engine 1 which must be cooled, as described above. The process air which has been compressed and heated in this manner is then added to the combustion chamber 2 in a manner which has already been explained.

[0070] Each of the working cylinders 30 is connected to the combustion chamber 2 of the axial piston engine 1 by means of a firing channel 39, so that the fuel/air mixture can pass out of the combustion chamber 2 via the firing channel 39 and into the working cylinder 30, and can drive the working piston 31 there.

[0071] In this respect the working medium flowing out of the combustion chamber 2 can be supplied successively to at least two working cylinders 30 via at least one firing channel 39, wherein one firing channel 39 is provided per working cylinder 30, which firing channel can be closed and opened by means of a control piston 40. The number of the control pistons 40 of the axial piston engine 1 is thus also predefined by the number of the working cylinders 30.

[0072] The firing channel 39 in this case is closed essentially by means of the control piston 40 with its piston cover 41. The control piston 40 is driven by means of a control piston curved path 42, wherein a spacer 43 for the control piston curved path 42 to the drive shaft 38 is provided, which is also used in particular for thermal decoupling. In the present exemplary embodiment, the control piston 40 can execute an essentially axially oriented stroke movement 44. To this end, each control piston 40 is guided by means of sliding blocks (not numbered) which are mounted in the control piston curved path 42, wherein the sliding blocks in each case have a securing cam which runs back and forth in a guide groove (not numbered) and prevents the control piston 40 from rotating.

[0073] As the control piston 40 comes into contact with the hot working medium from the combustion chamber 2 in the region of the firing channel 39, it is advantageous if the control piston 40 is water-cooled. To this end, the axial piston engine 1 has a water-cooling system particular in the region of the control piston 40, the water-cooling system 45 comprises inner 45, in wherein cooling channels 4 6, intermediate cooling channels 4 7 and outer cooling channels 48. Well-cooled in this manner, the control piston 40 can be moved in an operationally reliable manner in a corresponding control piston cylinder 49.

[0074] The firing channels 39 and the control pistons 40 can be provided in the axial piston engine 1 in a particularly simple manner in design terms if the axial piston engine 1 has a firing channel ring 50 as is illustrated in particular in FIG. 3.

[0075] The firing channel ring 50 has a centre axis 51, around which in particular the parts of the working cylinders 30 and the control piston cylinders 49 of the axial piston engine 1 are concentrically arranged. A firing channel 39 is provided between each working cylinder 30 and control piston cylinder 49, wherein each firing channel 39 is connected spatially with a recess 52 (see FIG. 3) of a combustion chamber bottom 53 (see FIG. 1) of the combustion chamber 2 of the axial piston engine 1. The working medium can thus pass from the combustion chamber 2 via the firing channels 39 and into the working cylinders 30, and carry out work there, by means of which the compressor cylinders 33 of the axial piston engine 1 can also be moved. It is self-evident that, depending on the actual configuration, coating and inserts can also be provided in order to protect the firing channel ring 50 or its material from direct contact with corrosive combustion products or excessive temperatures.

[0076] The alternative control piston 60 which is shown by way of example in FIGS. 4 and 5 has a wheel 61 for the control piston curved path 37 of the axial piston engine 1. The wheel 61 is provided on an end 64 of the control piston 60 which faces away from the piston cover 41 in the same manner as a rotation securing means 63 which is configured as a ball 62. The ball 62 can advantageously also be used as a longitudinal guide of the control piston 60 in the present case. Furthermore, the control piston 60 comprises a piston ring 65, which is situated directly below the piston cover 41. The piston ring 65 is secured on the control piston 60 by means of a piston ring securing means 66. A pressure compensation means 67 for the control piston 60 is also provided between the piston ring 65 and the ball 62.

LIST OF REFERENCE SYMBOLS

[0077] 1 Axial piston engine [0078] 2 Combustion chamber [0079] 3 First region [0080] 4 Second region [0081] 5 Preparation chamber [0082] 6 Main combustion chamber [0083] 7 Prechamber [0084] 8 Main chamber [0085] 9 Main nozzle [0086] 10 Preparation nozzle [0087] 11 Main combustion direction [0088] 12 Axis of symmetry [0089] 13 Angle [0090] 14 Jet direction of preparation nozzle [0091] 15 Jet direction of main nozzle [0092] 16 Intersection point [0093] 17 Separate air supply [0094] 18 Process air supply [0095] 19 Further air supply [0096] 20 Perforated rim [0097] 21 Ceramic assembly [0098] 22 Ceramic combustion chamber wall [0099] 23 Profiled tube [0100] 24 cooling air chamber [0101] 25 cooling air chamber supply [0102] 30 working cylinder [0103] 31 working piston [0104] 32 Compressor piston [0105] 33 Compressor cylinder [0106] 34 Connection rod [0107] 35 Connection rod wheel [0108] 36 Drive curved path [0109] 37 Drive curved path support [0110] 38 Drive shaft [0111] 39 Firing channel [0112] 40 Control piston [0113] 41 Piston cover of control piston [0114] 42 Control piston curved path [0115] 43 Spacer for control piston curved path [0116] 44 Axially oriented stroke movement [0117] 45 Water-cooling system [0118] 46 Inner cooling channels [0119] 47 Intermediate cooling channels [0120] 48 Outer cooling channels [0121] 49 Control piston cylinder [0122] 50 Firing channel ring [0123] 51 Centre axis [0124] 52 Recess [0125] 53 Combustion chamber bottom [0126] 60 Alternative control piston [0127] 61 Wheel [0128] 62 Ball [0129] 63 Rotation securing means [0130] 64 End facing away [0131] 65 Piston ring [0132] 66 Piston ring securing means [0133] 67 Pressure-compensating means