[0001] The invention relates to a steam engine, i.e. a heat engine that performs mechanical
work using steam as its working fluid. More particular, the invention relates to a
piston steam engine preferably for use in power generation.
[0002] Piston steam engines are known already since the 18
th century. One specific type as disclosed in
US 4,050,357 A,
WO 2010/099941 A1,
JP 57-212311 A or
JP 57-135209 A comprises a cylinder and a steam chamber to be supplied with live steam, wherein
the steam chamber has an opening for introducing live steam into the cylinder and
a valve seat.
[0004] In addition, a valve member is disclosed, which is urged against the valve seat by
an elastic element in a closing position closing the opening. In addition, all these
documents disclose a piston slidable between a bottom dead center and top dead center
having a projection at its top end facing the opening and being configured to lift
the valve member against the spring force of the elastic element from the valve seat,
when the piston approaches the top dead center for releasing the opening and introducing
steam into the cylinder. The elastic element in these documents is formed by a spring
which is either directly disposed inside the steam chamber or supported by a casing,
in turn being disposed within the steam chamber.
[0005] Such steam engines are operated at relatively high pressures between 40 bar - 150
bar and high temperatures between 300°C and 600°C to achieve a desired efficiency
(it should be clear that the invention is not limited to such pressure and temperature
ranges). However, the relaxation behavior of the spring is heavily influenced when
directly or indirectly disposing the spring in the hot steam chamber.
[0006] Moreover
WO 2010/099941 A1 and
US 4,050,357 A both use a plate or disc like valve member without any particular guidance of the
valve member. The disc-like or plate-like valve members, therefore, tend to break
easily, thus not providing for a sufficient lifetime of the steam engine. In addition
the little guidance of the valve members bears the risk of an undefined opening behavior
of the valve.
[0007] JP 57-212311 A and
JP 57-135209 A suggest a valve member, which is translationally guided within a supporting housing
disposed in the steam chamber. Thus, also here and as described earlier, the relaxation
behavior of the spring is greatly influenced. In addition, disposing the valve member
within a supporting housing requires steam channels within the supporting housing.
This complicates the structure and bears the risk of relatively short maintenance
intervals because of the high pressure of the steam acting on the elements.
[0008] In addition, this relatively complicated structure is not sufficiently rigid to allow
a long lifetime of the steam engine, when considering the large impact of the projection
of the piston contacting the valve member for opening the valve. In particular, the
forces of the valve train are in an example in a range between 4000 N and 5000 N,
which results in excessive wear and, thus, a reduced lifetime.
[0009] Further steam engines are known, which use a valve member having a shaft and a valve
disc such as
DE 10-2012 001 630 A1 or
US 3,638,533 A. However, all these documents require a relatively complicated operating mechanism
for lifting the valve and are, hence, complicated to assemble and maintain. In addition,
these devices are relatively expensive, because of the complicated structure.
In view of the aforesaid, it is the object of the invention to provide a steam engine
that has a relatively long maintenance interval, is easy to assemble, simple, inexpensive
and provides for a defined opening behavior of the valve.
[0010] This object is solved by a steam engine as defined in claim 1. Preferred embodiments
of the invention are defined in the dependent claims.
[0011] The basic idea is the use of a shaft valve that is a valve having a shaft and a valve
disc at one end of the shaft, as the valve member to be opened by a projection of
the piston when the piston approaches the top dead center. Such a shaft valve enables
to position the elastic element e.g. spring such as a steel spring, outside the steam
chamber and, hence, in a less hot portion of the steam engine without the need of
a complicated construction. Thereby, the relaxation behavior of the spring is not
influenced by the hot steam and a well-defined opening behavior of the valve may be
achieved. In addition, a shaft valve is very reliable valve member in regard of stability
under load and provides for a good guidance possibility.
[0012] In one embodiment, a steam engine is suggested comprising a cylinder and a steam
chamber to be supplied with live steam. The steam chamber has an opening for introducing
live steam into the cylinder and a valve seat. The opening is preferably centered
relative to the cylinder. Thereby, it may be prevented that live steam, introduced
into the cylinder, excessively contacts the walls of the cylinder. Furthermore, in
the present application "the opening" is always considered as the main opening for
introducing live steam into the cylinder. Even if further openings and valves (sub-openings
and sub-valves) as described later are provided, these usually have a smaller isentropic
flow cross section as compared to the main opening and the main valve. The valve seat
is preferably defined by a portion or edge surrounding the opening. Further, the steam
engine comprises a valve member. The valve member is that member of a valve which
is movable and in a particular case slidable to open and close the valve or the opening
to which the valve is associated. The valve member is urged against the valve seat
in a closing position, i.e. the portion or edge surrounding the opening, by an elastic
element and the pressure of the steam inside the steam chamber. The elastic element
may be a spring, particularly a steel spring. The elastic element may as well be formed
by a plurality of coaxially arranged springs. The closing position defines the closed
position of the valve, in which the opening of the steam chamber is closed and hence,
is sealed so that no steam from the steam chamber may be introduced into the cylinder.
In this context, the spring is particularly needed for initiating closing of the valve
and a reproducible valve movement, particularly preventing valve fluttering.
[0013] Further, the steam engine comprises a piston, slidable within the cylinder between
a bottom dead center and a top dead center. The piston has a projection at its top
end facing the opening, wherein the projection is used for lifting the valve member
against a spring force of the elastic element from the valve seat, when the piston
is in the area of the top dead center that is, approaches the dead center. As such,
the valve member is pushed and lifted towards the steam chamber by the movement of
the piston for releasing the opening and allowing steam from the steam chamber to
be introduced to the cylinder via the opening. According to this embodiment, the valve
member has a shaft, which extends through the steam chamber and a valve disc disposed
at the first end of the shaft. As described earlier, because the valve is lifted into
the steam chamber, the steam within the steam chamber acts on the upper surface of
the valve disc and the valve is in the closed position and thereby assists the elastic
element in urging the valve member onto the valve seat in the closing position. In
addition, the use of the shaft enables to position the elastic element outside the
steam chamber (in an axial direction of the shaft) at the second end of the shaft
opposite to the first end at which the valve disc is disposed. In other words, the
second end of the shaft is disposed outside the steam chamber a preferably a certain
distance of more than 20mm away from the steam chamber. Thereby, the relaxation behavior
of the spring is not influenced by the hot steam within the steam chamber and a defined
opening behavior of the valve may be achieved.
[0014] Further, the piston is made from a light metal or light metal alloy such as aluminum
or aluminum alloy, which provides for high damping and good running characteristics
of the piston. On the other hand, the surface of the projection which contacts the
valve disc for opening the valve member and to which the high temperature steam is
applied is made from a different material, preferably a material with higher rigidity
such as stainless steel.
[0015] According to an embodiment, the steam engine is additionally provided with a valve
guide. The valve guide is used for translationally guiding the shaft of the valve
member. The valve guide is preferably arranged outside the steam chamber and may border
the steam chamber at one side extending towards the second end. Thereby, a defined
opening behavior may be achieved at the same time increasing the stability of the
movement of the valve member. As a result, the life cycle of the valve may be increased
and the maintenance interval be prolonged. The valve guide may be made of graphite
antimony which in combination with a chromed shaft provides for a translational guide
with a very low amount of play and makes the use of a lubricant unnecessary. In particular,
the presence of water contained in the wet steam is sufficient to provide for an excellent
lubrication. However, any other lubricant-free guide or any other guide that uses
water as lubricant is conceivable. Yet, the above mentioned material combination has
been proven most reliable and suitable for the steam engine described herein and having
a relatively small valve lift.
[0016] In order to even further improve the opening behavior of the valve, the ratio of
the guiding length, that is the length at which the shaft of the valve member is guided
in the valve guide and the maximum valve lift of the valve member when being lifted
by the projection of the piston is at least 70, preferably at least 80, more preferably
at least 90 and most preferred at least 100. Thereby a relatively long guidance of
the shaft may be achieved and the tilting of the valve member in the guidance can
be avoided leading to a very well-defined opening behavior of the valve member.
[0017] In this context, it is also preferable that at least 50%, preferably 60%, more preferably
at least 75% and most preferred at least 80% of the length of the shaft are guided
by the valve guide. In one particular embodiment, a concave fillet is formed between
the valve disc and the valve shaft. The valve guide is preferably provided so that
the valve guide extends up to the end of the concave fillet opposite to the valve
disc, when the valve member is in the opening position that is lifted from the valve
seat.
[0018] The valve lift depends on the stroke of the piston and, hence, the output of the
engine. As such, the valve lift relative to the isentropic flow cross-section is less
than 0,25, preferably less than 0,2 and more preferably less than 0,17. In one particular
example, the valve lift can be below 3.5 mm and preferably within a range of 0.50
mm and 3.0 mm, preferably 0.50 mm and 2.0 mm. In another example the valve lift corresponds
to less than 3%, preferably less than 2% and more preferably less than 1% of the stroke
of the piston. Certainly, the valve lift is larger than 0.1%, preferably larger than
0.3% and more preferably more than 0.4%. By reducing the valve lit in this manner,
the injection period is reduced whereas the expansion period is increased. Thereby
a more efficient engine may be provided. In addition, a smaller valve lift leads to
less wear and, therefore, less maintenance.
[0019] The above steam engine has been described as a one cylinder engine. However, a plurality
of said cylinders may be implemented.
[0020] According to another embodiment, which may as well be implemented without the piston
being used for opening the valve member by means of its projection and the shaft valve,
is a steam engine which may have the previously described features and additionally
has a cylinder head unit having a first housing body provided with the steam chamber
and the opening and having an open end with an inner surface, and a second housing
body having an outer surface, wherein the inner surface and conical outer surface
are engaged. In one embodiment, a recess is formed in the inner and outer surfaces
so as to define a hollow space when the inner and outer surfaces are engaged, whereby
the material of the cylinder head having a relatively high thermal conductivity is
reduced and less heat is conducted from the steam chamber toward the top of the cylinder
head away from the cylinder. For this purpose, it is preferred that the recesses are
formed above the steam chamber. Additionally or alternatively, the inner surface and
the outer surface are each conical and sealingly engaged. An engine in which these
aspects are independently implemented may be a steam engine comprising a cylinder,
a steam chamber to be supplied with live steam and having an opening for introducing
live steam into the cylinder and a valve seat as well as a valve member urged against
a valve seat by an elastic element in a closing position closing the opening and having
the first and second housing body as previously described. Particularly, the steam
chamber is mainly defined by the first housing body but has an open end at one side,
which has a conical inner surface. By fixing the second housing body to the first
housing body, the conical outer surface of the second housing body and the conical
inner surface of the first housing body engage so as to form a very secure sealing.
Thereby it can surely be prevented that high temperature and high pressure steam from
the steam chamber escapes at the top of the cylinder head unit thus providing for
a very safe engine.
[0021] For ease of assembly, it is preferred that the conical inner surface is disposed
at the side of the first housing opposite to the opening for introducing live steam
into the cylinder.
[0022] This is one feature that enables assembly of the entire engine in only one direction.
[0023] Another feature assisting this assembly is that the center axis of the cone of the
conical inner surface, and hence the conical outer surface is aligned with the center
axis of the opening and/or the center axis of the cylinder. In principle, it is preferred,
that the entire engine has a substantial symmetrical configuration, which is advantageous
from the viewpoint of load distribution, ease of manufacture and assembly.
[0024] Further assisting the easy assembly is that the valve guide is provided within the
second housing body. That is, the valve member, the valve guide and second housing
body may be pre-assembled and by fixing the first and second housing bodies, also
the valve member is assembled.
[0025] Preferably, the first and second housing bodies are fixed together by screws. If
the screws extend substantially parallel to the center axis of the cylinder, the assembly
may be performed in one direction as previously explained. "Substantially" in this
regard means, that there may of course be a certain deviation from the parallel orientation
of the screws up to ±40° as long as the screw heads are accessible from one direction,
e.g. the top.
[0026] Furthermore, it is preferred to have a top cover and screw the top cover to the crankcase
by screws. If the screws again extend substantially parallel to the center axis of
the cylinder the assembly may again be achieved in only one direction and from one
side, e.g. the top. Further, by the use of the top cover screwed to crankcase, the
cylinder head unit may be clamped between the top of the cylinder and the top cover
and hence be fixed without the need of further attachment means and sealing. In addition,
a metal sealing ring may be used between the top of the cylinder and the bottom of
the cylinder head unit which makes the steam engine less complicated and less expensive
with an easy assembly.
[0027] Furthermore, the top cover also enables very easy assembly and pre-tensioning of
the valve member in that the elastic element particularly the spring is inserted after
the cylinder unit has been mounted on the cylinder at the second end of the shaft
of the valve and is automatically pre-tensioned by attaching the top plate and screwing
the top plate to the crankcase. In addition, the top cover is preferably configured
to have a relatively high heat capacity and thereby extracts heat from the elastic
element (the spring) thereby assisting the maintenance of a constant relaxation behavior
of the elastic element. Additionally, cooling ribs or fins may be provided at the
top cover and being directed toward the environment, i.e. away from the spring. Thereby,
heat may be conducted away from the spring assisting the aforesaid effect. Furthermore,
a relatively high pre-tension may be achieved, which again provides for a well-defined
and controlled opening behavior of the valve preventing valve fluttering. The pre-tensioning
may be adjusted by means of the top cover and - if necessary - the use of washers
between the spring and the top cover and/or the spring and the cylinder head. By these
measures, not only the spring, but also the screws are disposed relatively far away
from the relatively high temperature steam chamber, preferably, the distance between
the screws and/or elastic element is more than 100 mm, preferably more 120 mm. Moreover,
this may provide for the advantage that relatively inexpensive springs such as spring
steel springs may be used as they do not need to be heat resistant. These kinds of
springs are relatively insensitive and have a long lifetime as compared to specific
other springs, which is important considering the high valve train forces.
Furthermore, in order to balance a certain small play between the valve guide and
the valve member, it is preferred, that the valve seat or the edge of the valve disc
is spherical (curved) and the edge of the valve disc or the valve seat is chamfered.
In particular, the combination of a spherical surface at one element and a chamfer,
that is flat surface at the other element, it may be achieved, that the two elements
find their optimum position automatically and balance some manufacturing tolerances
or play in between the elements. In this context, "optimum position" does not necessarily
always mean the same position. Rather, this pair (spherical/chamfered) ensures that
the two elements will always find a line of contact ensuring leak tightness. Another
important issue is that the valve member particularly the valve disc and the valve
seat have a matching hardness, i.e. a similar hardness, so as to prevent biting of
one element into the other, thereby, avoiding damaging of the sealing surfaces.
[0028] Furthermore, it is preferred that the engine is a uniflow engine that is that the
steam flows from the steam chamber through the opening into the cylinder at a top
of the cylinder and is exhausted from the cylinder at a bottom of the cylinder. Thereby
it is achieved, that the live steam is not cooled by exhaust steam exhausted from
the cylinder whereby the efficiency of the entire engine is improved. For this purpose,
the cylinder has exhaust openings released during movement of the piston to the bottom
dead center for exhausting the steam from the cylinder. These exhaust openings are
formed near the bottom of the cylinder or in other words closer to the bottom than
to the top.
[0029] According to another embodiment, the surface of the projection facing the opening
is convex and the portion of the valve disc facing the projection is flat. Thereby,
an optimum pressure point of the projection against the valve member for lifting the
valve member may be achieved. At the same time, the convex surface of the projection
serves as a baffle plate for preventing that the steam impinges on the top face of
the piston. This is of particular importance, if the piston is made from a light metal
such as aluminum (see later) which tends to be more sensible with respect to the hot
live steam. In addition, the baffle plate serves for a better distribution of the
steam into the cylinder for having a steam distribution at the top of the cylinder
which is as uniform as possible.
[0030] For example, the projection may be made as a different element and be connected to
the piston by means of a form fit, a force fit and/or an adhesive bond.
[0031] A further embodiment implements the provision of an additional opening (sub-opening)
in the steam chamber, preferably with a smaller area (e.g. diameter or isentropic
flow cross section) closed by an additional valve member (sub-valve). Moreover, the
piston comprises an additional projection facing the additional opening. When the
piston approaches the top dead center, the additional projection lifts the additional
valve member releasing the additional opening before the projection lifts the valve
member releasing the opening. As the area of the additional opening closed by the
additional valve member is smaller than that of the opening closed by the valve member,
the force required for lifting the additional valve member is a smaller and, thus,
the impact forces on the valve member can be reduced as compared to the case in which
only the valve member and the opening are provided. In one embodiment more than one
additional opening and additional valve member may be provided, in which instance
it is preferred to dispose the additional opening and additional valve member symmetrically,
particularly diametrically opposite to each other.
[0032] Further features and advantages of the invention, which may be implemented alone
or in combination with any of the other features described beforehand are disclosed
in the following description of a preferred embodiment. This description refers to
the accompanying drawings in which:
Fig. 1 shows a schematic cross section of a steam engine according to one embodiment
of the invention with the valve member in the closing position and the piston in the
bottom dead center; and
Fig. 2 shows the same cross section as Fig. 1 with the valve member in the opening
position and the piston at the top dead center.
[0033] The steam engine shown in Fig. 1 has a cylinder 10. The cylinder 10 has a top end
11 and a bottom end 12. At bottom end 12, the cylinder 10 is connected to a crankcase
20. A plurality of exhaust openings 13 are circumferentially provided in the cylinder
wall 14 of the cylinder. The exhaust openings 13 communicate a cylinder chamber 15
with a ring chamber 16 for exhausting used steam from the cylinder chamber 15 to the
ring chamber 16. The exhaust openings 13 are disposed near a bottom dead center of
a piston 30.
[0034] The piston 30 is translationally moveable along the center axis CA of the cylinder
10 between a bottom dead center (Fig. 1) and a top dead center (Fig. 2). The piston
30 is connected to a non-shown crank shaft accommodated in the crankcase 20 via a
non-shown piston connection rod or piston con rod. The piston 30 has a sealing ring
31 at its bottom end 32 and plural sealing rings 31 at its top end 33.
[0035] Further, a projection 34 is provided at its top end 33. The projection 34 has a convex,
preferably spherical surface 35, which is preferably made from a different material
than a main body 36 of the piston 30. The material is preferably more rigid than the
material of the main body 36. It is also preferred that the material has a relatively
low thermal conductivity in order to prevent heat from being transferred to the main
body 36 of the piston. As regards rigidity and thermal conductivity it is preferred
to use stainless steel. The main body 36 is preferably made from a light metal, preferably
aluminum or aluminum alloy to provide good running characteristics of piston 30 within
the cylinder 10. The material of the projection 34 and particularly its surface 35
is selected for the purpose of opening the later described valve member 52 and for
distributing live steam introduced into the cylinder chamber 15 acting as a baffle
plate.
[0036] The engine further comprises a cylinder head unit 40. The cylinder head unit 40 has
a first housing body 41 and a second housing body 42. Further provided is an opening
43 with a preferably circular shape. The center axis of the opening 43 is aligned
with center axis CA of the cylinder 10. Further, the opening 43 is provided in the
first housing body 41. Further, the cylinder head unit 40 has a steam chamber 44 to
be supplied with live steam through one or more openings, which are not shown in the
drawings. The steam chamber 44 is mainly defined in the first housing body 41 but
with one open side opposite to the opening 43. In particular, the first housing body
41 has a first end 45 facing the cylinder 10 and particularly the cylinder chamber
15. The opening 43 is provided at this first end 45. Opposite to this first end 45,
the first housing body has a second end 46 facing away from the cylinder chamber 15
or to put it differently opposite the opening 43 at the first end 45. This second
end 46 is provided with a conical inner surface 47 and is open.
[0037] The second housing body 42 has a conical outer surface 48. The conical inner surface
47 and the conical outer surface 48 are sealingly engaged with each other. In this
context, it is preferred, that the cone angle of the surfaces 47 and 48 are different
to a small extent (e.g. equal to or less than 4°, more preferred equal to or less
than 2°). Alternatively or additionally, one of the surfaces 47, 48 may be provided
with a higher surface roughness than the other surface so as to provide for a certain
biting of one of the surface into the other, thus, creating kind of a labyrinth sealing.
Thus by engaging the surfaces, a secure sealing is achieved which may be as strong
that if the screws 62 described later are removed, the first and second housing body
41 and 42 still maintain fixed to each other. The cones of the surfaces 47 and 48
are preferably centered with the center axis relative to the center axis CA of the
cylinder and the opening 43.
[0038] Moreover, an annular recess 71 and 72 is formed in each of the surfaces 47 and 48
so as to form an annular hollow space 70. Thereby, the material of the cylinder head
unit is reduced at the position of the hollow space 70 forming an interruption in
the thermal conductivity. As a result, less heat is conducted from the steam chamber
44 to the top, where the spring 60 and the screws 62 and 63 are located.
[0039] The second housing body 42 additionally comprises a bottomed hole 49. A valve guide
50 is press fit into the bottomed hole 49 of the second housing body 42. The valve
guide 50 is preferably made from graphite antimony (Guides having such a material
are for example available from SGL CARBON SE, Wiesbaden, Germany). A through hole
51 is provided at the bottom of the bottomed hole in the second housing body 42.
[0040] A valve member 52 having a shaft 53 translationally guided within the valve guide
50 passes through the through hole 51. The shaft 53 has a first end 54 facing the
opening 43 and being connected to a valve disc 55 via a concave fillet 56. A second
end 57 of shaft 53 extends beyond the cylinder head unit 40 extending (protruding)
from the through hole 51.
[0041] The valve disc 55 has an outer edge 58, which is configured spherical and rests on
a valve seat 59 at the edge surrounding the opening 43. This edge 59 of the opening
43 is chamfered. A spring 60 as an elastic element is provided at the second end 57
of the shaft 53 and is positioned outside the steam chamber 44.
[0042] The first and second housing bodies 41 and 42 are screwed together by means of screws
62 which extend parallel to the center axis CA of the cylinder 10. A top cover 61
is screwed by means of screws 63 to the crankcase 20. The screws 63 also extend parallel
to the center axis CA.
[0043] The top cover 61 additionally has a recess 64 for accommodating the spring 60. The
spring 60 is thereby supported by the top cover 61 at one end 65 and a plate 66 connected
to the shaft 53 of the valve member 52 at the other end 67. Thereby, the valve member
52 is pre-tensioned or urged towards the valve seat 59, whereby the valve disc (particularly
its edge 55) is pressed against the valve seat 59 thereby sealingly closing the steam
chamber 44 or its opening 43, respectively in the closing position of the valve member
52.
[0044] The shaft 52 has a length SL of 150 mm, defined between its two ends 54 and 57. The
length of the valve guide 50 referred to as GL is 120 mm. Thus, the shaft 53 is guided
along 80% of its length.
[0045] In addition, the valve lift is 1 mm in the present embodiment so that the ratio of
the shaft length to the valve lift in the present embodiment is 150. The valve lift
is particular defined as the movement of the valve member between the position in
Fig. 1 and the position in Fig. 2.
[0046] Next, the assembly process of the engine shown in Figs. 1 and 2 is described.
[0047] First, the cylinder 10 is placed with a shoulder 70 at an opening of the crankcase
20 with the piston being inserted into the cylinder 10.
[0048] Further, the cylinder unit 40 is pre-assembled the valve guide 50 inserted into the
bottomed hole 49 and then the shaft 53 inserted into the opening of the valve guide
50. Subsequently, the first and second housing bodies 41 and 42 are connected by inserting
the outer conical surface 48 into the inner conical surface 47 and fixing the bodies
by tightening the screws 62. The preassembled cylinder head unit 40 is placed with
its shoulder 71 at the top end 11 of the cylinder 10.
[0049] In a next step, the spring 60 is placed on the plate 66 and the top cover 61 is positioned.
Subsequently, the screws 63 are tightened to fix the top cover 61 to the crankcase
20 whereby the cylinder 10 and the cylinder head unit 40 are clamped and the spring
60 is pre-tensioned.
[0050] It becomes apparent from the above description, that the assembly is fairly easy
and may be performed from one direction, namely the top. All the screws may be tightened
from the top and all the elements may be inserted from the top. This is not only advantageous
from the perspective of the manufacturing process, i.e. the assembly during the first
manufacture, but also from maintenance point of view.
[0051] Finally, the function of the engine is described in the following.
[0052] In Fig. 1, the piston 30 is disposed in the bottom dead center. In this stage, live
steam is stored in the steam chamber 44 and its high pressure assisted by the spring
60 urges the valve disc 55 or particularly its spherical edge 58 against the valve
seat 58 thereby closing the opening 43.
[0053] When the piston 30 translationally moves along center axis CA towards its top dead
center as shown in Fig. 2, the convex surface 35 of the projection 34 contacts the
flat lower surface 73 of the valve disc 55 thereby pushing the valve member 52 towards
the top into the steam chamber and releasing (lifting) the valve disc or particularly
its edge from the valve seat 59 thereby releasing the opening 43. Thus, live steam
from the steam chamber 44 is introduced into the cylinder chamber 15 forcing the piston
30 again towards its bottom dead center.
[0054] Upon movement of the piston 30 towards the bottom dead center by means of the live
steam, the projection 34 particularly its surface 35 comes again out of contact with
the valve member 52 which is thereby closed by means of the spring 60 again closing
the opening 43. Once the piston 30 reaches its bottom dead center, the exhaust openings
13 are released and the steam is exhausted to the ring chamber 16. This process is
continued during operation of the engine.
1. Steam engine comprising:
a cylinder (10)
a steam chamber (44) to be supplied with live steam, the steam chamber (44) having
an opening (43) for introducing live steam into the cylinder (10) and a valve seat
(59),
a valve member (52) urged against the valve seat (59) by an elastic element (60) in
a closing position closing the opening (43),
a piston (30) slidable within the cylinder (10) between a bottom dead center and a
top dead center,
wherein the piston (30) has a projection (34) at its top end (33) facing the opening
(43), the projection (34) lifting the valve member (52) against a spring force of
the elastic element (60) from the valve seat (59), when the piston (30) is in the
area of the top dead center for releasing the opening (43), characterized in that
the valve member has a shaft (53), extending through the steam chamber (44), and a
valve disc (55) disposed at a first end (54) of the shaft (53), wherein the elastic
element (60) is disposed outside the steam chamber (44) at a second end (57) of the
shaft (53) opposite to the first end (54);
wherein the piston (30) is made from a light metal or light metal alloy and at least
a surface (35) of the projection (34) is made of a different material than the piston
and having a higher rigidity.
2. Steam engine according to claim 1, further comprising a valve guide (50) translationally
guiding the shaft (53) of the valve member (52).
3. Steam engine according to claim 2, wherein the ratio of the guiding length (GL), corresponding
to the length at which the shaft (53) of the valve member (52) is guided in the valve
guide (50), and the maximum valve lift when being lifted by the projection (34) is
at least 70, preferably at least 80, more preferably at least 90 and most preferred
at least 100.
4. Steam engine according to claim 1 or 3, wherein at least 50%, preferably at least
60%, more preferably at least 75% and most preferred at least 80% of the length of
the shaft (53) are guided by the valve guide (50).
5. Steam engine according to any one of the preceding claims, wherein the elastic element
(60) is directly or indirectly pre-tensioned by a top cover (61).
6. Steam engine according to claim 5, wherein the elastic element (60) is supported by
the top cover (61) at one end (65) and a plate (66) connected to the shaft (53) of
the valve member (52) at another end (67).
7. Steam engine according to claim 5 or 6, wherein the top cover (61) screwed to a crankcase
(20) by screws (63), the screws (63) preferably extending substantially parallel to
the center axis (CA) of the cylinder (10).
8. Steam engine according to any one of the preceding claims, wherein the valve seat
(59) or the edge of the valve member (52) is spherical and the edge of the valve member
(52) or the valve seat (59) is chamfered.
9. Steam engine according to any one of the preceding claims, wherein the cylinder has
exhaust openings (13) released during movement of the piston (30) to the bottom dead
center for exhausting the steam from the cylinder (10).
10. Steam engine according to any one of the preceding claims, wherein a surface (35)
of the projection (34) facing the opening (43) is convex and the portion of the valve
member (52) facing the projection (34) is flat.
11. Steam engine according to any one of the preceding claims, further comprising at least
one further valve member urged against a further valve seat by a further elastic element
in a closing position closing a further opening, the piston (30) having a further
projection at its top end facing the further opening, the further projection lifting
the further valve member against a spring force of the further elastic element from
the further valve seat, when the piston is in the area of the top dead center for
releasing the further opening in advance of the projection (34) lifting the valve
member (52) against the spring force of the elastic element (60) from the valve seat
(59).
12. Steam engine according to any one of the preceding claims, wherein the valve member
has a valve disc (54) at a first end of the shaft opposite to the second end.
13. Steam engine according to any one of the preceding claims, wherein a distance between
the steam chamber (44) and the elastic element (60) is more than 100 mm, preferably
more than 120 mm.
14. Steam engine according to any one of the preceding claims, wherein the second end
of the shaft is disposed more than 20 mm away from the steam chamber.
1. Dampfmaschine, die umfasst:
einen Zylinder (10)
eine Dampfkammer (44), die mit Frischdampf zu versorgen ist, wobei die Dampfkammer
(44) eine Öffnung (43) für das Einführen von Frischdampf in den Zylinder (10) und
einen Ventilsitz (59) aufweist,
ein Ventilelement (52), das von einem elastischen Element (60) in einer Schließposition,
die die Öffnung (43) schließt, gegen den Ventilsitz (59) gedrückt wird,
einen Kolben (30), der innerhalb des Zylinders (10) zwischen einem unteren Totpunkt
und einem oberen Totpunkt gleitbar ist,
wobei der Kolben (30) einen Vorsprung (34) an seinem Oberseitenende (33), der Öffnung
(43) zugewandt, aufweist, wobei der Vorsprung (34) das Ventilelement (52) gegen eine
Federkraft des elastischen Elements (60) von dem Ventilsitz (59) anhebt, wenn der
Kolben (30) in dem Bereich des oberen Totpunkts ist, um die Öffnung (43) freizugeben,
dadurch gekennzeichnet, dass
das Ventilelement einen Schaft (53) aufweist, der sich durch die Dampfkammer (44)
erstreckt, und einen Ventilteller (55), der an einem ersten Ende (54) des Schafts
(53) angeordnet ist, wobei das elastische Element (60) außerhalb der Dampfkammer (44)
an einem zweiten Ende (57) des Schafts (53), dem ersten Ende (54) entgegengesetzt,
angeordnet ist;
wobei der Kolben (30) aus einem Leichtmetall oder einer Leichtmetalllegierung hergestellt
ist und mindestens eine Oberfläche (35) des Vorsprungs (34) aus einem Material hergestellt
ist, das von dem des Kolbens unterschiedlich ist und eine höhere Starrheit aufweist.
2. Dampfmaschine nach Anspruch 1, die weiter eine Ventilführung (50) umfasst, die den
Schaft (35) des Ventilelements (52) translatorisch führt.
3. Dampfmaschine nach Anspruch 2, wobei das Verhältnis der Führungslänge (GL), die der
Länge entspricht, an der der Schaft (53) des Ventilelements (52) in der Ventilführung
(50) geführt ist, und des maximalen Ventilhubs bei Anheben durch den Vorsprung (34)
mindestens 70, vorzugsweise mindestens 80, bevorzugter mindestens 90 und besonders
bevorzugt mindestens 100 beträgt.
4. Dampfmaschine nach Anspruch 1 oder 3, wobei mindestens 50 %, vorzugsweise mindestens
60 %, bevorzugter mindestens 75 % und besonders bevorzugt mindestens 80 % der Länge
des Schafts (53) von der Ventilführung (50) geführt sind.
5. Dampfmaschine nach einem der vorstehenden Ansprüche, wobei das elastische Element
(60) direkt oder indirekt von einer Oberseitenabdeckung (61) vorgespannt ist.
6. Dampfmaschine nach Anspruch 5, wobei das elastische Element (60) von der Oberseitenabdeckung
(61) an einem Ende (65), und einer Platte (66), die mit dem Schaft (53) des Ventilelements
(52) verbunden ist, an dem anderen Ende (67) getragen wird.
7. Dampfmaschine nach Anspruch 5 oder 6, wobei die Oberseitenabdeckung (61) an ein Kurbelgehäuse
(20) durch Schrauben (63) geschraubt ist, wobei sich die Schrauben (63) vorzugsweise
im Wesentlichen parallel zu der Mittelachse (CA) des Zylinders (10) erstrecken.
8. Dampfmaschine nach einem der vorstehenden Ansprüche, wobei der Ventilsitz (59) oder
die Kante des Ventilelements (52) sphärisch ist, und die Kante des Ventilelements
(52) oder der Ventilsitz (59) abgefast ist.
9. Dampfmaschine nach einem der vorstehenden Ansprüche, wobei der Zylinder Abgasöffnungen
(13) aufweist, die während Bewegung des Kolbens (30) zu dem unteren Totpunkt freigegeben
werden, um den Dampf aus dem Zylinder (10) abzulassen.
10. Dampfmaschine nach einem der vorstehenden Ansprüche, wobei eine Oberfläche (35) des
Vorsprungs (34), die der Öffnung (43) zugewandt ist, konvex ist, und der Abschnitt
des Ventilelements (52), der dem Vorsprung (34) zugewandt ist, flach ist.
11. Dampfmaschine nach einem der vorstehenden Ansprüche, die weiter mindestens ein weiteres
Ventilelement umfasst, das gegen einen weiteren Ventilsitz von einem weiteren elastischen
Element in einer Schließposition, die eine weitere Öffnung schließt, gedrückt wird,
wobei der Kolben (30) einen weiteren Vorsprung an seinem Oberseitenende aufweist,
der der weiteren Öffnung zugewandt ist, wobei der weitere Vorsprung das weitere Ventilelement
gegen eine Federkraft des weiteren elastischen Elements von dem weiteren Ventilsitz
abhebt, wenn der Kolben in dem Bereich des oberen Totpunkts ist, um die weitere Öffnung
zu öffnen, bevor der Vorsprung (34) das Ventilelement (52) gegen die Federkraft des
elastischen Elements (60) von dem Ventilsitz (59) anhebt.
12. Dampfmaschine nach einem der vorstehenden Ansprüche, wobei das Ventilelement einen
Ventilteller (54) an einem ersten Ende des Schafts, dem zweiten Ende entgegengesetzt,
aufweist.
13. Dampfmaschine nach einem der vorstehenden Ansprüche, wobei ein Abstand zwischen der
Dampfkammer (44) und dem elastischen Element (60) mehr als 100 mm, vorzugsweise mehr
als 120 mm beträgt.
14. Dampfmaschine nach einem der vorstehenden Ansprüche, wobei das zweite Ende des Schafts
mehr als 20 mm von der Dampfkammer weg angeordnet ist.
1. Moteur à vapeur comprenant:
un cylindre (10),
une chambre de vapeur (44) à alimenter en vapeur vive, la chambre de vapeur (44) ayant
une ouverture (43) pour introduire de la vapeur vive dans le cylindre (10) et un siège
de soupape (59),
un organe de soupape (52) poussé contre le siège de soupape (59) par un élément élastique
(60) dans une position de fermeture fermant l'ouverture (43),
un piston (30) pouvant coulisser à l'intérieur du cylindre (10) entre un point mort
bas et un point mort haut,
dans lequel le piston (30) a une saillie (34) à son extrémité supérieure (33) faisant
face à l'ouverture (43), la saillie (34) soulevant l'organe de soupape (52) sous l'effet
d'une force de rappel de l'élément élastique (60) depuis le siège de soupape (59),
lorsque le piston (30) est dans la zone du point mort haut pour libérer l'ouverture
(43), caractérisé en ce que
l'organe de soupape a un arbre (53), s'étendant à travers la chambre de vapeur (44),
et un disque de soupape (55) disposé à une première extrémité (54) de l'arbre (53),
dans lequel l'élément élastique (60) est disposé à l'extérieur de la chambre de vapeur
(44) à une seconde extrémité (57) de l'arbre (53) à l'opposé de la première extrémité
(54) ;
dans lequel le piston (30) est constitué d'un métal léger ou d'un alliage de métal
léger et au moins une surface (35) de la saillie (34) est constituée d'un matériau
différent de celui du piston et ayant une rigidité supérieure.
2. Moteur à vapeur selon la revendication 1, comprenant en outre un guide de soupape
(50) guidant en translation l'arbre (53) de l'organe de soupape (52).
3. Moteur à vapeur selon la revendication 2, dans lequel le rapport de la longueur de
guidage (GL), correspondant à la longueur à laquelle l'arbre (53) de l'organe de soupape
(52) est guidé dans le guide de soupape (50), et la levée de soupape maximale lorsqu'elle
est soulevée par la saillie (34) est au moins 70, de préférence au moins 80, plus
préférentiellement au moins 90 et le plus préférentiellement au moins 100.
4. Moteur à vapeur selon la revendication 1 ou 3, dans lequel au moins 50 %, de préférence
au moins 60 %, plus préférentiellement au moins 75% et le plus préférentiellement
au moins 80 % de la longueur de l'arbre (53) sont guidés par le guide de soupape (50).
5. Moteur à vapeur selon l'une quelconque des revendications précédentes, dans lequel
l'élément élastique (60) est directement ou indirectement précontraint par un couvercle
supérieur (61).
6. Moteur à vapeur selon la revendication 5, dans lequel l'élément élastique (60) est
supporté par le couvercle supérieur (61) à une extrémité (65) et une plaque (66) reliée
à l'arbre (53) de l'organe de soupape (52) à une autre extrémité (67).
7. Moteur à vapeur selon la revendication 5 ou 6, dans lequel le couvercle supérieur
(61) est vissé à un carter moteur (20) par des vis (63), les vis (63) s'étendant de
préférence sensiblement parallèlement à l'axe central (CA) du cylindre (10).
8. Moteur à vapeur selon l'une quelconque des revendications précédentes, dans lequel
le siège de soupape (59) ou le bord de l'organe de soupape (52) est sphérique et le
bord de l'organe de soupape (52) ou le siège de soupape (59) est biseauté.
9. Moteur à vapeur selon l'une quelconque des revendications précédentes, dans lequel
le cylindre a des ouvertures d'échappement (13) libérées pendant un déplacement du
piston (30) jusqu'au point mort bas pour l'échappement de la vapeur depuis le cylindre
(10).
10. Moteur à vapeur selon l'une quelconque des revendications précédentes, dans lequel
une surface (35) de la saillie (34) faisant face à l'ouverture (43) est convexe et
la portion de l'organe de soupape (52) faisant face à la saillie (34) est plate.
11. Moteur à vapeur selon l'une quelconque des revendications précédentes, comprenant
en outre au moins un autre organe de soupape poussé contre un autre siège de soupape
par un autre élément élastique dans une position de fermeture fermant une autre ouverture,
le piston (30) ayant une autre saillie à son extrémité supérieure faisant face à l'autre
ouverture, l'autre saillie soulevant l'autre organe de soupape sous l'effet d'une
force de rappel de l'autre élément élastique depuis l'autre siège de soupape, lorsque
le piston est dans la zone du point mort haut pour libérer l'autre ouverture à l'avance
de la saillie (34) soulevant l'organe de soupape (52) sous l'effet de la force de
rappel de l'élément élastique (60) depuis le siège de soupape (59).
12. Moteur à vapeur selon l'une quelconque des revendications précédentes, dans lequel
l'organe de soupape a un disque de soupape (54) à une première extrémité de l'arbre
à l'opposé de la seconde extrémité.
13. Moteur à vapeur selon l'une quelconque des revendications précédentes, dans lequel
une distance entre la chambre de vapeur (44) et l'élément élastique (60) est supérieure
à 100 mm, de préférence supérieure à 120 mm.
14. Moteur à vapeur selon l'une quelconque des revendications précédentes, dans lequel
la seconde extrémité de l'arbre est disposée à plus de 20 mm de la chambre de vapeur.