EP2598719A1

EP2598719A1 - Piston engine drivable using a steam power process

Info

Publication number: EP2598719A1
Application number: EP11729990.9A
Authority: EP
Inventors: Nadja Eisenmenger; Hans-Christoph Magel; Andreas Wengert
Original assignee: Robert Bosch GmbH
Current assignee: Robert Bosch GmbH
Priority date: 2010-07-28
Filing date: 2011-07-06
Publication date: 2013-06-05
Also published as: DE102010038543A1; WO2012013463A1; US20130118174A1; CN103026002A

Abstract

A piston engine (1) that can be driven using a steam power process and is used in particular for utilizing the waste heat from an internal combustion engine comprises a cylinder bore (5), a cylinder piston (6) which is arranged in the cylinder bore (5) and delimits an operating space (8) in the cylinder bore (5), a rod (21) which is connected to the cylinder piston (6), and a bearing point (37) on which the rod (21) and the cylinder piston (6) connected to the rod (21) are mounted. A peripheral gap (28) is predefined between the cylinder piston (6) and the cylinder bore (5), thus preventing frictional wear between the cylinder piston (6) and the cylinder bore (5), which is particularly advantageous when a water-based working fluid is conducted through the operating space (8) since steam has no lubricity.

Description

Description title

About a steam power process drivable piston engine prior art

The invention relates to a drivable via a steam power piston engine. Specifically, the invention relates to a piston engine which can be driven by a steam power process and serves to utilize the waste heat of an internal combustion engine.

Internal combustion engines convert the energy of the fuel into mechanical energy for driving vehicles and the like. However, a considerable part of the energy is released as waste heat, which is led away by the cooling system or in the exhaust gas from the internal combustion engine. To use this heat energy, it is conceivable that a steam power process is coupled to the internal combustion engine. In this way, the heat energy from the internal combustion engine can be used to generate steam, which is expanded in an expansion engine and thus provides further energy that can be used to drive the vehicle or to generate auxiliary energy. Here, however, there is a problem that the steam engine is driven by steam or a similar fluid from the steam power process, which has no lubricity, whereby a wear of the steam engine is favored.

DISCLOSURE OF THE INVENTION The piston engine according to the invention with the features of claim 1 has the advantage that an advantageous operation of the piston engine is also possible when using water or other, poorly lubricating working fluids. This affects among other things in a reduced wear on the cylinder piston and in a longer

Life of the piston engine off.

The measures listed in the dependent claims are advantageous

Further developments of the piston machine specified in claim 1 possible. It is advantageous that the piston engine, which can be driven via the steam power process, is combined with an internal combustion engine in order to convert the waste heat of the internal combustion engine via the steam power process into additional drive energy. Such a combination for waste heat utilization is particularly efficient in a commercial vehicle, since here the internal combustion engine gives off a large power and thus a large amount of heat for steam generation is available. As a result, the fuel consumption can be reduced.

Especially for use in commercial vehicles with diesel engine or gas engine is designed as a reciprocating steam engine piston engine with Scotch-yoke crank mechanism of particular advantage. This can be about the same speed range for the

Piston machine can be achieved as well as for the internal combustion engine and thus the mechanical energy emitted by the piston engine can be delivered directly to the crankshaft of the diesel engine or gas engine. In addition, such a piston engine can be conveniently mounted in a limited space on an internal combustion engine.

Advantageously, the steam process can be configured as an ORC process (Organic Rankine Cycle Process). The thermal energy of the waste heat is converted into mechanical energy via the ORC process. As a result, the waste heat from an exhaust gas of the internal combustion engine or an exhaust gas recirculation can advantageously be transmitted via a heat exchanger to the working fluid of the ORC process. The working fluid may in this case be based at least essentially on water. To the

Heat exchanger, the working fluid can be evaporated. This steam can then be expanded in the piston machine serving as an expansion machine, whereby the mechanical energy is recovered. The working fluid is then in a

Cooled condenser and fed to a pump. The working fluid can thereby be compressed in the liquid phase by the pump to the pressure level for re-evaporation at the heat exchanger. As a result, the cycle is closed.

By the storage of the rod at the bearing point, the load on the cylinder piston can be reduced in an advantageous manner. In particular, lateral forces on the cylinder pistons can be reduced as a result of this bearing, since these are absorbed at the bearing point. Advantageously, in this case an outer diameter of an outer side of the cylinder piston is smaller than an inner diameter of the cylinder bore.

This ensures that the cylinder piston is not applied directly to the cylinder bore serving as a cylinder bore and serving between the working piston

Cylinder piston and the cylinder bore (cylinder wall) no force is transmitted. Of the Cylinder piston in this case has a sufficient circumferential gap to the

Cylinder bore on. In conjunction with the storage on the rod also serving as a transmission rod, a stable and well-guided bearing for the cylinder piston can be realized.

Especially on the cylinder piston, the occurrence of wear is critical because it works with a poorly lubricating working fluid (working fluid). In particular, the working piston can work with water vapor, which has no lubricity. Through the gap between the cylinder piston and the cylinder bore, the occurrence of such wear is prevented or at least reduced. In an advantageous manner, at least one sealing element is arranged on the outside of the cylinder piston. Here, it is also advantageous that on the outside of the cylinder piston a circumferential

Recess is configured that the sealing element is designed as an annular sealing element and that the annular sealing element is inserted into the circumferential recess on the outside of the cylinder piston. Specifically, the circumferential

Recess may be formed on the outside of the cylinder piston by a circumferential annular groove. As a result, the tightness on the cylinder piston can be increased in an advantageous manner in order to prevent or at least reduce an undesired escape of the gaseous working fluid, in particular of the water vapor, via the gap between the cylinder piston and the cylinder bore. In order to increase the tightness of the piston, in this case especially additional sealing elements in the form of piston rings or the like can be used.

It is also advantageous that the rod at least substantially rigid with the

Cylinder piston is connected, that the bearing point is formed by a bearing bore in which the rod is guided and that the cylinder piston is aligned by the leadership of the rod in the bearing bore at least approximately centered on a longitudinal axis of the cylinder bore. As a result, an advantageous storage of the cylinder piston with respect to the cylinder bore at the bearing by means of the rod is possible. It can be prevented over the life of the piston engine wear on the working piston. The bearing bore may for example be designed on a housing part which is arranged between the cylinder bore and a crankshaft space. As a result, an advantageous media separation on the bearing bore is possible. Specifically, a lubricating oil may be provided in the crankshaft space to lubricate a crankshaft and other components disposed in the crankshaft space.

It is also advantageous that the rod from the cylinder bore on the

Bearing point is guided in the crankshaft space that in the crankshaft space the Crankshaft is arranged and that the rod cooperates by means of a crank loop with the crankshaft.

Furthermore, it is advantageous that at least one further cylinder bore, a further cylinder piston arranged in the further cylinder bore, which delimits a further working space in the further cylinder bore, a further rod which is at least indirectly connected to the further cylinder piston and at least one further bearing point are provided wherein the further rod is mounted on the further bearing point and wherein between the further cylinder piston and the further cylinder bore, a circumferential gap is predetermined. Further, it is advantageous that the further rod is substantially rigidly connected to the other cylinder piston, that the further bearing point is formed by a further bearing bore, in which the further rod is guided, and that the further cylinder piston by the leadership of the further rod in the further bearing bore is aligned at least approximately centered on a longitudinal axis of the further cylinder bore. The further rod is in this case preferably connected to a crank arranged in the piston chamber. This can be an advantageous

Crank grinding drive can be realized. In particular, it is advantageous if the two bearing points, such as the entire remaining crank drive, are lubricated with oil. In the oil sector can be realized by a stable and well-managed storage. This may optionally be provided an additional media separation, which connects directly to the bearings. Thereby, an improved separation of the oil from the working fluid can be achieved. Thus, a particularly low-wear piston machine with lubricated oil crank loop and without direct contact between the cylinder piston and the cylinder wall of the cylinder bore can be realized. The storage of the working piston on each of a transmission rod without respective contact with the cylinder bore can be used in an advantageous manner in designed as a reciprocating steam engines piston engines. However, this embodiment is particularly advantageous in a designed as a reciprocating steam engine piston engine with crank grinding (Scotch Yoke).

Advantageously, an outer diameter of an outer side of the other

Cylinder piston specified smaller than an inner diameter of the other

Cylinder bore. Furthermore, it is advantageous that on an outer side of the other

Cylinder piston at least one sealing element is arranged. This can be a

appropriate configuration may be provided, as it is also realized in the cylinder piston.

Short description of the drawing Preferred embodiments of the invention are explained in more detail in the following description with reference to the accompanying drawings. 1 shows a piston machine in a schematic sectional illustration according to an exemplary embodiment of the invention.

EMBODIMENTS OF THE INVENTION FIG. 1 shows a piston engine 1 in a schematic illustration according to an exemplary embodiment of the invention. The piston engine 1 is connected via a

Steam power process powered. Here, the piston engine 1 can be used, for example, in an internal combustion engine of a motor vehicle to use the waste heat of the internal combustion engine. The piston engine 1 then converts the waste heat into mechanical energy, which can serve, for example, as additional drive energy or for driving an auxiliary aggregate, in particular an electric generator. However, the piston engine 1 according to the invention is also suitable for others

Use cases. The piston engine 1 of the exemplary embodiment has a housing part 2 and cylinders 3, 4 connected to the housing part 2. On the cylinder 3, a cylinder bore 5 is formed, in which a cylinder piston 6 is arranged. The

Cylinder bore 5 has a longitudinal axis 7, along which the cylinder piston 6 is displaceable. The cylinder piston 6 bounded in the cylinder bore 5 on the one hand a working space 8 and on the other hand a pressure-relieved space 9. On the cylinder 3, a valve-controlled inlet 10 and a valve-controlled outlet 1 1 are provided for the working space 8. Via the valve-controlled inlet 10 compressed, gaseous working fluid, in particular water vapor, can be guided into the working space 8. When relaxing the gaseous working fluid in the working chamber 8, an actuating force is exerted on the cylinder piston 6, which leads to an adjustment of the

Cylinder piston 6 in a direction 12 along the longitudinal axis 7 leads. In this case, the volume of the working space 8 increases while the volume of the pressure-relieved space 9 decreases. The pressure-relieved space 9 is connected via an outlet 13 with a

Low pressure region of the steam circuit connected so that in the pressure-relieved space 9 reaching working fluid is returned to the steam circuit.

Within the housing part 2, a crankshaft space 15 is provided. By doing

Crankshaft 15 is a crankshaft 16 with a crankshaft journal 17 is arranged. An axis of rotation of the crankshaft 16 is in this case oriented perpendicular to the longitudinal axis 7. In addition, a crank loop 18 is arranged in the crankshaft space 15. The

Crank loop 18 has a slot-shaped recess 19 into which a sliding block 20 is inserted. The sliding block 20 is in this case on the crankshaft journal 17th

arranged. The cylinder piston 6 is connected via a rod 21 with the crank loop 18. As a result, an operative connection between the cylinder piston 6 and the crankshaft 16 is formed, so that the lifting movement of the cylinder piston 6 in a

Rotary movement of the crankshaft 16 is translated.

In addition, the cylinder 4 of the piston engine 1, a further cylinder bore 5 ', in which a further cylinder piston 6' is arranged. In this case, the further cylinder piston 6 'is guided along the longitudinal axis 7 of the cylinder bore 5'. The longitudinal axis 7 serves as a common longitudinal axis 7 for the two cylinder bores 5, 5 'of the cylinder 3, 4th

The cylinder piston 6 'delimited in the cylinder bore 5' another working space 8 'and a further pressure-relieved space 9'. Here are on the cylinder 4, a valve-controlled inlet 10 'and a valve-controlled outlet 1 1' for the other

Working space 8 'provided. Further, an outlet 13 'for the pressure-relieved space 9' is provided to return from the working space 8 'in the pressure-relieved space 9' reaching working fluid in the steam circuit.

Thus, gaseous working fluid can also be passed through the working space 8 '. During the expansion of the gaseous working fluid in the working space 8 ', the cylinder piston 6' is actuated counter to the direction 12. The lifting movement of the cylinder piston 6 'is in this case transmitted via a further rod 21' on the crank loop 18. The further rod 21 'in this case connects the cylinder piston 6' with the crank loop 18th

Thus, the crank loop 18 is connected on the one hand via the rod 21 with the cylinder piston 6 and on the other hand via the rod 21 'with the cylinder piston 6'. As a result, an alternating actuation of the crank loop 18 in and against the direction 12 is possible. Thus, a Scotch-Yoke drive can be realized in an advantageous manner.

The cylinder piston 6 has an outer side 25. On the outer side 25, the cylinder piston 6 has an outer diameter 26. In addition, an inner diameter 27 of the cylinder bore 5 is predetermined. The outer diameter 26 of the cylinder piston 6 and the inner diameter 27 of the cylinder bore 5 are coordinated. Here, the outer diameter 26 of the outer side 25 of the cylinder piston 6 is smaller than the inner diameter 27 of the cylinder bore 5. As a result, a gap 28 between the outer side 25 of the cylinder piston 6 and the cylinder bore 5 is predetermined. Of the predetermined gap 28 ensures a certain distance of the cylinder piston 6 of the cylinder bore 5 during operation. A contact between the cylinder piston 6 and the cylinder bore 5 is in this case avoided over the entire stroke range of the cylinder piston 6.

During operation of the piston engine 1, there is the problem that the gaseous working fluid provided in the working space 8, in particular the water vapor, has no or only poor lubricating properties. Adequate lubrication of the

Cylinder piston 6 in the cylinder bore 5 to avoid Reibverschleißes can not be guaranteed. By the predetermined gap 28, however, frictional wear is prevented. In this case, vaporous working fluid can pass from the working space 8 into the pressure-relieved space 9 via the gap 28. However, this working fluid is returned via the outlet 13 in the steam circuit. In addition, the cylinder piston 6 in this embodiment annular recesses 29, 30 on. The circumferential recesses 29, 30 are configured here as annular grooves. In the annular grooves 29, 30 annular sealing elements 31, 32 are used. The annular sealing elements 31, 32 form a seal between the working space 8 and the pressure-relieved space 9 with respect to the predetermined gap 28.

In this embodiment, a housing part 35 is provided, which is connected to the cylinder 3. Here, the housing part 35 is arranged between the cylinder bore 5 of the cylinder 3 and the crankshaft space 15. On the housing part 35 is a bearing bore

36 configured, which forms a bearing 37 for the rod 21. As a result, the rod 21 is mounted in the bearing bore 36, wherein the bearing bore 36 allows movement of the rod 21 along the longitudinal axis 7. By the storage of the rod 21 at the bearing

37 occurring transverse forces are absorbed. As a result, the sealing elements 31, 32 are relieved and there is a contact between the cylinder piston 6 and the

Cylinder bore 5 prevents. The cylinder piston 6 is in this case additionally guided by the sealing elements 31, 32 in the cylinder bore 5. In a rigid connection of the rod 21 with the cylinder piston 6, a guide through the sealing elements 31, 32 is not required.

Accordingly, the cylinder piston 6 'on an outer side 25', which has a

Outer diameter 26 'has. Furthermore, the cylinder bore 5 'has a

Inner diameter 27 'on. In this embodiment, the outer diameter 26, 26 'of the cylinder piston 6, 6' given the same size. In addition, also the

Inner diameter 27, 27 'of the cylinder bores 5, 5' given the same size. Thus, also on the cylinder piston 6 ', a gap 28' between the outside 25 'and the Cylinder bore 5 'formed. The gap 28 'prevents direct contact of the

Cylinder piston 6 'and the cylinder bore 5'. In addition, on the cylinder piston 6 'circumferential recesses 29', 30 'are provided in the annular sealing elements 31', 32 'are used. Furthermore, a housing part 35 'is provided between the

Cylinder bore 5 'and the crankshaft space 15 is arranged. On the housing part 35 ', a bearing bore 36' is configured, in which the rod 21 'is mounted. The bearing bore 36 'thus forms a bearing 37' for the rod 21 '. Thus, also on the cylinder 4, an advantageous storage of the cylinder piston 6 'by means of the rod 21' at the bearing 37 'take place.

In this embodiment, the two rods 21, 21 'are rigidly connected to the crank loop 18. This is a two-sided storage of the crank loop 18 to the

Bearings 37, 37 'formed. Occurring shear forces in the transmission of

Lifting movement of the cylinder piston 6, 6 'on the crankshaft 16 can thus be advantageously recorded at the bearings 37, 37'.

Thus, an optimized storage of the working piston 6, 6 'serving cylinder piston 6, 6' of the designed as a reciprocating steam engine piston engine 1 is possible. Here, in this embodiment, the cylinder piston 6, 6 'with respect to the crankshaft 16 are arranged opposite to each other. The cylinder pistons 6, 6 'in this case transmit their power via the crank-wheel drive to the crankshaft 16. The inlet 10 and the outlet 1 1 for the cylinder 3 and the inlet 10 'and the outlet 1 1' for the cylinder 4 are preferably valve-controlled. By the crank grinding with the crank loop 18 and the sliding block 20, which sits on the crankshaft journal 17, the

Hubkolbenbewegung the cylinder piston 6, 6 'transmitted to the crankshaft 16. Here, the crank loop 18 of the crank grinding via the rods 21, 21 'to the

Bearings 37, 37 'stored, said storage receives the transverse forces occurring.

The bearing is in this case designed so that the cylinder pistons 6, 6 'are not present at their respective cylinder liners, which are predetermined in the cylinder bores 5, 5', and there transmit no forces. This avoids critical wear on these non-oil lubricated areas. The piston engine 1 can thereby the necessary

Achieve life expectancy. In order to reliably prevent frictional wear, sufficiently large gaps 28, 28 'are provided with respect to the cylinder liners. On the other hand, to increase the tightness of the cylinder piston 6, 6 'again, are additional in this embodiment Sealing elements 31, 32, 31 ', 32', in particular piston rings 31, 32, 31 ', 32', arranged on the cylinder piston 6, 6 '.

In addition, in this embodiment, the bearing bores 36, 36 'are oil lubricated. For this purpose, the bearing bores 36, 36 'are provided directly next to the crankshaft space 15, so that lubricating oil from the crankshaft space 15 for lubricating the bearings 37, 37' can serve. In order to avoid an entry of lubricating oil in the pressure-relieved spaces 9, 9 ', one or more sealing elements 38, 39, 38', 39 'can connect to the bearing points 37, 37'. Thus, a good and low-wear bearing the crank loop 18 can be ensured.

The invention is not limited to the described embodiments.

Claims

claims

1 . Piston engine (1), which is drivable via a steam power process, in particular for utilizing the waste heat of an internal combustion engine, with at least one cylinder bore (5), in the cylinder bore (5) arranged in the cylinder piston (6) in the

Cylinder bore (5) defines a working space (8), a connected at least indirectly with the cylinder piston (6) rod (21) and at least one bearing point (37) to which the rod (21) and the rod (21) connected to the cylinder piston (6) are mounted, wherein between the cylinder piston (6) and the cylinder bore (5) has a circumferential gap (28) is predetermined and wherein the rod (21) the cylinder piston (6) with a

Crank loop (18) connects.

2. Piston engine according to claim 1,

characterized,

an outer diameter (26) of an outer side (25) of the cylinder piston (6) is set smaller than an inner diameter (27) of the cylinder bore (5).

3. piston engine according to claim 1 or 2,

characterized,

in that at least one sealing element (31, 32) is arranged on an outer side (25) of the cylinder piston (6).

4. piston machine according to claim 3,

characterized,

that on the outer side (25) of the cylinder piston (6) at least one circumferential

Recess (29, 30) is configured such that the sealing element (31, 32) as an annular

Sealing element (31, 32) is configured and that the annular sealing element (31, 32) in the circumferential recess (29, 30) is inserted.

5. Piston machine according to one of claims 1 to 4,

characterized,

in that the rod (21) is at least substantially rigidly connected to the cylinder piston (6), that the bearing point (37) is formed by a bearing bore (36) in which the rod (21) is guided, and in that the cylinder piston (6 ) by the leadership of the rod (21) in the bearing bore (36) is aligned at least approximately centered on a longitudinal axis (7) of the cylinder bore (5).

6. Piston engine according to claim 5,

characterized,

the bearing bore (36) is configured in a housing part (35) which is arranged between the cylinder bore (5) and a crankshaft space (15).

7. Piston machine according to one of claims 1 to 6,

characterized,

that a crankshaft space (15) is provided, that the rod (21) from the

Cylinder bore (5) via the bearing (37) into the crankshaft space (15) is guided, that in the crankshaft space (15) a crankshaft (16) is arranged and that the rod (21) by means of the crank loop (18) with the crankshaft ( 16) cooperates.

8. Piston engine according to one of claims 1 to 7,

characterized,

in that at least one further cylinder bore (5 '), a further cylinder piston (6') arranged in the further cylinder bore (5 ') delimiting a further working space (8') in the further cylinder bore (5 '), forms a further rod (21st '), which is at least indirectly connected to the further cylinder piston (6'), and at least one further bearing point (37 ') are provided, wherein the further rod (21') at the further bearing point (37 ') is mounted and wherein between the further cylinder piston (6 ') and the further cylinder bore (5') a circumferential gap (28 ') is predetermined.

9. Piston machine according to claim 8,

characterized,

that the further rod (21 ') at least substantially rigid with the other

Cylinder piston (6 ') is connected, that the further bearing point (37') by a further bearing bore (36 ') is formed, in which the further rod (21') is guided, and that the further cylinder piston (6 ') through the Guiding the further rod (21 ') in the further bearing bore (36') at least approximately aligned on a longitudinal axis (7) of the further cylinder bore (5 ') centered.

10. piston engine according to claim 8 or 9,

characterized,

an outer diameter (26 ') of an outer side (25') of the further cylinder piston (6 ') is set smaller than an inner diameter (27') of the further cylinder bore (5 ') and or

in that at least one sealing element (31 ', 32') is arranged on an outer side (25 ') of the further cylinder piston (6').