EP2562351A1 - Steam motor - Google Patents

Abstract

The steam engine has a piston housing (1) inside which pistons (4,5) are reciprocated between top dead center and bottom dead center piston of workspace (2,3). The workspace walls (6,7) are formed in the workspace. The workspace walls are provided with vapor return space (8,9) in vapor-conducting connection with the working space, or other steam-carrying area of the steam engine.

Description

The present invention relates to a steam engine, in detail with the features of the preamble of claim 1.

Such steam engines are usually housed together with an internal combustion engine in a common drive train and both in vehicles, such as utility or rail vehicles, as well as in stationary systems such as (block) helzkraftwerken, which, for example, the gas of a biogas plant for power and heat generation burn, used.

In this case, the steam engine, if it is provided in particular in addition to the internal combustion engine, constitute a part of a closed steam cycle, which is supplied via the exhaust gas stream of the internal combustion engine, via this heat input in an evaporator, an initially liquid working medium is evaporated and with this steam of the steam engine is operated. In the latter, the vaporous working medium is expanded while performing mechanical work and subsequently fed to a condenser for liquefaction, in order to be subsequently collected in a reservoir and in turn fed to the evaporator via a pump for re-evaporation.

From the prior art, it is known to carry out such a steam engine as a reciprocating engine, then at least one cylindrical working space is provided in a piston housing in which a piston between a top dead center and a bottom dead center due to the incoming and outgoing steam in the working space and is movable. The movement of the piston is transmitted via a connecting rod to a crankshaft and thus converted into a rotational movement. Of course, two or more pistons, which are each movable in a corresponding working space back and forth, may be provided.

The working space enclosing the working space is exposed to the working space on the inside facing the high temperatures of the steam, which also can still result in a temperature gradient over the working space wall in the direction of movement of the piston, depending on the arrangement of the inlet valve and the outlet valve for the steam and in dependence Geometry of the working space. However, even the ever-present temperature gradient from the inside of the working space wall to the back of the working space wall facing away from the working space leads to an unfavorable thermal load and / or undesired thermal deformations.

US 1 551437 describes a steam engine in which the steam outlet has an annular chamber which extends around the working space wall in the area of the bottom dead center outside the working space. As a result, the unfavorable temperature gradient can not be compensated.

The present invention has for its object to provide a steam engine, in which the temperature gradient over the working space wall are reduced. The solution according to the invention should be inexpensive to produce and easy to integrate based on the conventional designs of steam engines.

The object of the invention is achieved by a steam engine according to the independent claim. The dependent claims represent expedient and particularly preferred embodiments of the invention.

A steam engine according to the invention comprises at least one working chamber enclosed by a piston housing and having a piston which can reciprocate in the working space between a top dead center and a bottom dead center, the working space being enclosed over its circumference by a working space wall inserted into or formed by the piston housing. In particular, the inlet and the outlet for the steam, over which all the steam expanding in the working space, with the exception of possible steam leaks, in particular via the piston, flows, are provided in the region of top dead center or bottom dead center.

The piston seals the working space at least except for a steam leak against the so-called crank chamber, in which a connecting rod connected to the piston and, as a rule, the crankshaft which is commanded by the piston via the connecting rod, is positioned.

According to the invention, a steam recirculation space is provided on a rear side of the working space wall facing away from the working space, which chamber is in vapor-conducting communication with the working space via the crank space. This ensures that that portion of steam, also called blow-by steam, which escapes through a gap between the outer surface of the piston and the inner surface of the working space wall and enters the crankcase and thus does not flow out via the outlet from the working space, still makes sense, namely can be used for temperature compensation on the working space wall.

By heating the back of the working space wall with the blow-by steam, the hitherto prevailing unfavorable temperature gradients can be reduced or avoided. In particular, when the steam is conducted along the entire rear side of the working space wall from the so-called cold end to the so-called hot end of the working space wall, a thermal compensation of the temperature profile over the working space wall can be achieved become. Such a hot end and cold end arise in particular when the steam inlet is designed in the region of top dead center so that the piston moves away from the hot steam inlet during expansion. In particular, that part of the working space wall which encloses the piston when it is in the region of the bottom dead center, may have a lower temperature than the area between the bottom dead center and the top dead center, so that in particular such a cold end can be formed.

In general, any steam or an arbitrarily branched portion of the steam supplied to the steam engine, wherein the diverted portion usually makes up only a fraction of the total steam volume flow, for example less than 10%, in particular only 1% of the steam engine supplied steam, for acting on the Vapor return chamber can be used to heat the back of the work space wall. According to the invention, at least one vapor fraction is used for this purpose, which in any case does not contribute to the mechanical work generated by the steam engine. Namely, such a vapor portion is the vapor which escapes through the gap between the piston and the working space wall, in the present case referred to as steam leakage, generally also known as blow-by. Such leakage usually occurs even when the piston is sealed against the working space wall via a piston seal, which may comprise one or more sealing rings or piston rings. In principle, however, it is also possible to carry out such a piston seal, with which the piston is sealed against the working space wall, simply by selecting a particularly small clearance between the piston and the working space wall.

For such use of steam leakage to back-heat the working space wall, the vapor conducting connection to the vapor return space extends from a vapor return inlet to one The orifice in the vapor return space and the vapor return inlet are formed, in part or entirely, by the gap sealed between the piston and the working space wall with the piston seal so as to direct the vapor leakage into the vapor return space. Such vapor recovery of steam leakage has no adverse effect on the efficiency of the steam engine. Rather, due to a lower thermal deformation due to temperature gradients, the efficiency can advantageously be increased.

Another advantage of using the steam leak to heat the rear of the working space wall is that a calming zone is formed by the vapor return space in which oil droplets can separate from the vapor leakage. Due to the contact of the steam leak with oil-lubricated areas of the steam engine, for example in the so-called crankcase, which connects below the bottom dead center of the piston housing, namely a mixing of the steam leakage or the leakage steam with oil can not be prevented.

Furthermore, heating of the working space wall in the region of bottom dead center over the entire cross section is achieved by the flow around the rear side of the working space wall through the steam discharged via the steam-conducting connection, whereby the temperature differences between upper end (above top dead center) and lower end (below bottom end) bottom dead center) of the working space wall - seen in the stroke direction of the piston - to be reduced. As a result, the thermo-mechanical loads of the working space wall and the provision of a working space forming bush, which reduces the socket, which at the same time the wear on the seal of the piston and thus the Dampfleckagemenge is significantly reduced. As a result, the life of such a steam engine is significantly increased.

Advantageously, the vapor return space extends along the working wall in the direction of movement of the piston. As a result, a uniform heating of the working space wall is achieved by the steam.

A uniform heating is also promoted by the fact that the vapor return chamber is designed as closed over the circumference of the working space wall annulus.

Alternatively, the vapor return space may only extend over part of the circumference of the working space wall.

According to one embodiment, a plurality of vapor-return steam chambers connected to one another are provided in the direction of movement of the piston, which are flowed through successively by the steam or the steam leakage from the working space.

Further, only the last steam return space in the flow direction of the steam or the steam leakage may be directly connected to the steam discharge passage.

Seen in the flow direction of the steam flowing through it, the vapor return space can open behind the vapor return inlet at a point of relatively low pressure, such as ambient pressure.

Preferably, the vapor return chamber is connected to a Dampfabführkanal for discharging the vapor from the vapor return chamber from the piston housing out, wherein a vapor return passage facing away from the vapor return passage in the region of bottom dead center or in the direction of top dead center opens outwardly in the piston housing. This can be achieved, for example, that the steam the working space wall over almost the entire wall length (seen in the stroke direction of the piston) substantially uniformly heated, whereby the thermo-mechanical loads of the working space wall are further reduced. On the other hand, if the steam above the piston or top dead center is directed into, for example, a cylinder head or valve cover, a slight removal of the rising steam can be achieved. Advantageously, an oil separator can be connected downstream of the steam discharge channel in the flow direction of the steam. Such an oil separator may alternatively be arranged in the vapor-conducting connection or a channel or space communicating therewith.

The steam engine may be associated with a device for valve control. The latter can have at least one inlet valve and one outlet valve, by means of which live steam is supplied to the working space controlled and exhaust steam, such as wet steam can be removed from the working space. Both intake and exhaust valves may be externally controlled in order to switch them independently of the speed or independent thereof. In particular, by means of a device belonging to the control device, the opening and closing times of the intake and exhaust valves can be variably adjusted.

The intake and exhaust valves can be arranged on the same side of the working space, for example in the region of top dead center, in a cylinder cover which delimits the working space at the top.

By using externally actuated valves, the steam engine can be more flexibly adapted to a varying steam flow rate supplied to it than would be the case if the intake and exhaust valves were formed by piston edges and corresponding cylinder openings, as in a two-stroke Otto engine.

According to a further embodiment, the working space wall is formed by a cylindrical bushing inserted into the piston housing, which is produced in particular from a material other than the piston housing. Thus, it is possible to use a material adapted to the tribological properties for the bush, which has high wear resistance, mechanical and thermal resistance and very good sliding properties. The piston housing, however, can be made of a less wear-resistant material or a material of lower quality.

The invention will now be explained with reference to an embodiment according to the accompanying figure.

Figur 1

einen Halbschnitt durch die Drehachse einer Kurbelwelle eines Dampfmotors.

It shows:

FIG. 1

a half-section through the axis of rotation of a crankshaft of a steam engine.

In FIG. 1 a steam engine according to the invention is shown in a half section through the axis of rotation of a crankshaft 16 of the steam engine, wherein in the present case only the above the axis of rotation extending components are shown.

The steam engine comprises a piston housing 1, which in the present case encloses two axially adjacent working spaces 2, 3, in each of which a piston 4, 5 is movable back and forth between a bottom dead center UT and a top dead center OT. Thus, the steam engine is designed as a reciprocating engine. Pistons 4, 5 are connected via connecting rods 17, 18 with corresponding cranks of the crankshaft 16.

In the present case, the crankshaft 16 is mounted in the piston housing 1 or in a subsequent to this crankcase, wherein the bearings and the connecting rods of the crankshaft 16 oil for cooling and / or lubrication is supplied via a lubricating oil supply, not shown.

In the present case, each of the working spaces 2, 3 has a working space wall 6, 7. Here, the working space wall 6, 7 is formed by a cylindrical bush inserted into a corresponding bore of the piston housing 1. As indicated by the dashed lines, each working space 2, 3 comprises an inlet 19 for supplying live steam to and an outlet 20 for discharging exhaust steam (wet steam) from the working space 2, 3. inlet 19 and outlet 20 are not shown, in particular operated externally operated valves of a valve control, also not shown, to release the inlet 19 and outlet 20 for steam alternately or close. Externally operated means that the valves are actuated, for example, via cams of a camshaft which rotates in a manner proportional to the rotational speed of the crankshaft 16 for opening and closing.

On the side facing away from the respective working space 2, 3 back of the working space wall 6, 7 each have a vapor return space 8, 9 is arranged. The latter is introduced into the piston housing 1, in the present case designed in the manner of a circumferential groove, so that working space wall 6, 7 and piston housing 1 define this vapor return space 8, 9 together. If both working spaces 2, 3 are arranged close to one another as here, then the two vapor return spaces 8, 9 of the respective working spaces 2, 3 can be flow-connected to one another, as indicated by the central web between the work spaces 2, 3. Here, each of the vapor return chambers 8, 9 extends along the working space wall 6, 7 in the direction of the movement direction of the piston 4, 5 and thus over part of the circumference of the working space wall 6, 7. In this case, as indicated by the dashed lines, a plurality of steam-recirculating vapor return chambers 8, 9 connected to one another, which are then flowed through successively by the steam or the steam leakage from the working space 2, 3.

To seal the pistons 4, 5 with respect to the working space wall 6, 7 piston seals 10, 11 are provided with two piston rings per piston 4, 5 in the present case. Of course, less or more than the illustrated piston rings or other type of seal could be provided for the production of the piston seal, even without piston rings.

The piston seals 10, 11 are intended to largely prevent the escape of steam via the gap between the piston 4, 5 and the working space wall 6, 7.

The despite the piston seals 10, 11 via the gap 13, 14 effluent volume flow of (leakage) steam is passed through a vapor-conducting connection in the vapor return chamber 8, 9. For this purpose, a vapor return inlet 12 is provided, which is arranged here below the bottom dead center UT at the end of the bush or the working space wall 6, 7 and introduced into the piston housing 1. The steam recirculation space 8, 9 is here permanently connected to the crankcase 21 in the piston housing 1 via the vapor return inlet 12. For this crankcase 21 counts on the one hand that subspace, which is bounded by the piston 4, 5 and the working space wall 8, 9, but separated from the working space 2, 3 by the piston seal 10, 11. On the other hand, the crank space 21 also includes that space which adjoins the partial space, which accommodates the connecting rod 17, 18 and crankshaft 16. The crank chamber 21 is not directly involved directly in a charge exchange during clocked operation of the steam engine, since it is not flowed through by the supplied or discharged main stream of steam.

Through the vapor return inlet 12, the steam leakage is passed into the adjoining vapor return chamber 8, 9. The vapor conducting connection thus extends from the vapor return inlet 12 to an orifice in the vapor return chamber 8, 9.

The steam recirculation space 8, 9 is in turn connected at its one, the steam recirculation inlet 12 remote from the end to a Dampfabführkanal 15. In the present case, the end of the Dampfabführkanals 15 facing away from the vapor return chamber 8, 9 in the region of the bottom dead center UT - here even below - arranged. This means that it is arranged between an upper edge of the piston 2 facing the working space 2 and a lower edge of the piston 2 facing the crankshaft 16. Of course, it would be conceivable that this could be arranged further above, that is between the top and bottom dead center or even beyond the top dead center in the piston housing 1. The Dampfabführkanal 15 may be followed by a corresponding oil separator for the separation of the oil carried by the steam or be integrated in the Dampfabführkanal 15. In the present case, only the last steam recirculation space in the flow direction of the steam or the steam leakage is connected directly to the steam exhaust duct 15.

LIST OF REFERENCE NUMBERS

1

piston housing

2, 3

working space

4, 5

piston

6, 7

Workroom wall

8, 9

Vapor recovery room

10, 11

piston seal

12

Vapor recovery inlet

13, 14

gap

15

Dampfabführkanal

16

crankshaft

17, 18

connecting rod

19

inlet

20

outlet

21

crankcase

Claims (11)

steam engine 1.1 with at least one of a piston housing (1) enclosed working space (2, 3); 1.2 with a in the working space (2, 3) between a top dead center (TDC) and a bottom dead center (UT) reciprocally movable piston (4, 5); in which 1.3 the working space (2, 3) is enclosed over its circumference by a in the piston housing (1) inserted or formed by this working space wall (6, 7) and by the piston (4, 5) against a crank chamber (21) having a on the piston (4,5) connected to the connecting rod (17, 18) encloses, is sealed, characterized in that 1.4 on a the working space (2, 3) facing away from the back of the working space wall (6, 7), a vapor return chamber (8, 9) is provided, which via the crank chamber (21) in vapor-conducting connection with the working space (2, 3). Steam engine according to claim 1, characterized in that the piston (4, 5) is sealed by a piston seal (10, 11) against the working space wall (6, 7) to allow vapor to escape through a gap (13, 14) between the piston (4, 5) and working space wall (6, 7) to avoid possible steam leakage, and the vapor-conducting connection of a vapor return inlet (12), the steam from the working space (2, 3) receives, to at least one orifice in the vapor return passage (8, 9) extends, wherein the vapor return inlet (12) partially or exclusively by the sealed with the piston seal (10, 11) gap (13, 14) between the piston (4, 5) and working space wall (6, 7) to direct the steam leakage into the vapor return space (8, 9). Steam engine according to claim 1 or 2, characterized in that the vapor return chamber (8, 9) is connected to a vapor discharge channel (15) for discharging the vapor from the vapor return chamber (8, 9) out of the piston housing (1) and a vapor return chamber (8). 8, 9) facing away from the end of the Dampfabführkanals (15) in the region of the bottom dead center (UT) or in the direction of top dead center (TDC) above the outside in the piston housing (1) opens. Steam engine according to one of claims 1 to 3, characterized in that the vapor return space (8, 9) extends along the working space wall (6, 7) in the direction of movement of the piston (4, 5). Steam engine according to one of claims 1 to 4, characterized in that the vapor return chamber (8, 9) as over the circumference of the working space wall (6, 7) closed annular space is executed. Steam engine according to one of claims 1 to 4, characterized in that the vapor return chamber (8, 9) only over a part of the circumference of the working space wall (6, 7) extends. Steam engine according to one of claims 1 to 6, characterized in that in the direction of movement of the piston (4, 5) a plurality of vapor-conductively connected vapor return chambers (8, 9) are provided which successively from the steam or the steam leakage from the working space (2, 3) be flowed through. Steam engine according to claim 7, characterized in that only the flow direction of the steam or the steam leakage last Vapor return space (8, 9) is connected directly to the Dampfabführkanal (15). Steam engine according to one of claims 1 to 8, characterized in that the working space wall (6, 7) by a in the Kolbungsgehäuse (1) inserted cylindrical bush, which is in particular made of a different material than the piston housing (1) is formed. Steam engine according to one of claims 3 to 9, characterized in that the Dampfabführkanal (15) is arranged downstream of an oil separator. A steam engine according to any one of claims 3 to 10, characterized in that the steam discharge duct (15) is provided in addition to an inlet (19) and outlet (20) for steam in and out of the working space (2, 3).

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