Title: Internal combustion engine comprising a hydraulic system
Abstract: An internal combustion engine includes a hydraulic system with a hydraulic pump. A lubricant system for moving parts of the engine is also provided, which includes a lubricant pump. To enable making the engine smaller, it is proposed that the hydraulic pump is connected to the lubricant system in such a way that it can be lubricated by the lubricant.
Patent Number: 6,854,431 Issued on 02/15/2005 to Gaessler, et al.
| Inventors:
|
Gaessler; Hermann (Vaihingen, DE);
Diehl; Udo (Stuttgart, DE);
Mischker; Karsten (Leonberg, DE);
Walter; Rainer (Pleidelsheim, DE);
Rosenau; Bernd (Tamm, DE);
Franzl; Stefan (Drancy, FR);
Schiemann; Juergen (Markgroeningen, DE);
Grosse; Christian (Kornwestheim, DE);
Beuche; Volker (Stuttgart, DE);
Reimer; Stefan (Markgroeningen, DE)
|
| Assignee:
|
Robert Bosch GmbH (Stuttgart, DE)
|
| Appl. No.:
|
297426 |
| Filed:
|
May 19, 2003 |
| PCT Filed:
|
February 19, 2002
|
| PCT NO:
|
PCT/DE02/00586
|
| 371 Date:
|
May 19, 2003
|
| 102(e) Date:
|
May 19, 2003
|
| PCT PUB.NO.:
|
WO02/08187 |
| PCT PUB. Date:
|
October 17, 2002 |
Foreign Application Priority Data
| Apr 06, 2001[DE] | 101 17 094 |
| Current U.S. Class: |
123/90.12; 123/90.13; 123/90.15; 123/90.33; 123/196R; 123/446; 184/6.5 |
| Intern'l Class: |
F01L 009//02 |
| Field of Search: |
184/6.5,6.9
123/90.12,90.13,90.33,196 R,196 C,90.15,90.16,90.17,446
417/228,364
|
References Cited [Referenced By]
U.S. Patent Documents
| 5186129 | Feb., 1993 | Magnan et al. | 123/90.
|
| 5697336 | Dec., 1997 | Eisenbacher et al. | 123/324.
|
| 5878710 | Mar., 1999 | Ritter et al. | 123/198.
|
| 5894830 | Apr., 1999 | Blass.
| |
| 5915348 | Jun., 1999 | Scheidt.
| |
| 6148805 | Nov., 2000 | Bartley.
| |
| 6261069 | Jul., 2001 | Djordjevic | 417/313.
|
| 6318974 | Nov., 2001 | Itoh et al. | 417/315.
|
| Foreign Patent Documents |
| 31 37 600 | Apr., 1983 | DE.
| |
| 40 33 105 | Apr., 1992 | DE.
| |
| 42 17 910 | Dec., 1993 | DE.
| |
| 198 27 932 | Jan., 1999 | DE.
| |
| 0 503 635 | Sep., 1992 | EP.
| |
Primary Examiner: Denion; Thomas
Assistant Examiner: Corrigan; Jaime W
Attorney, Agent or Firm: Greigg; Ronald E.
Parent Case Text
CROSS-REFERENCE TO RELATED APPLICATIONS
This application is a 35 USC 371 application of PCT/DE 02/00586 filed on
Feb. 19, 2002.
Claims
What is claimed is:
1. An internal combustion engine (10), comprising
a hydraulic system (32) that includes a hydraulic pump (34), and
a lubricant system (14), for lubricating moving parts of the engine (10)
including a lubricant pump (16), the hydraulic pump (34) being connected
to the lubricant system (14) in such a way that lubricant is pumped from
the lubricant pump (16) through a line (48) to the hydraulic pump (34) for
lubricating the hydraulic pump (34), wherein the hydraulic pump (34) pumps
a hydraulic fluid that differs from the lubricant of the lubricant system
(14) of the engine (10), wherein the hydraulic fluid has a lower
viscosity.
2. The engine (10) of claim 1, further comprising a filter (20, 50), is
disposed in the line (48) between the lubricant system (14) and the
hydraulic pump (34).
3. The engine (10) of claim 1, wherein the hydraulic system (32) comprises
a power unit (30) connected to a gas exchange valve (26) of the engine
(10) in such a way that this valve can be at least one of opened and
closed by the power unit (30).
4. The engine (10) of claim 1, wherein the hydraulic pump (34) is driven by
the engine (10).
5. The engine (10) of claim 4, wherein the hydraulic pump (34) is connected
directly to a crankshaft (40) of the engine (10).
6. The engine (10) of claim 4, wherein the hydraulic pump (34) is connected
to moving parts (40) of the engine (10) via a gear mechanism (38) with a
variable gear ratio.
Description
BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention relates to an internal combustion engine, having a hydraulic
system which includes a hydraulic pump, and having a lubricant system, for
moving parts of the engine, which includes a lubricant pump.
2. Description of the Prior Art
One engine of the type with which this invention is concerned is known on
the market. For its moving parts, such as pistons, crankshaft, and so
forth, a forced-circulation lubrication is provided, which is supplied
from an oil sump via an oil pump. At the same time, in the known engine, a
hydraulic system is provided which is used to actuate the inlet and outlet
valves of the engine. The known engine accordingly has no camshaft. Such
an engine has the advantage that the control times for the inlet and
outlet valves are independent of the position of the piston of the
applicable cylinder. Depending on the operating state of the engine, such
as high rpm, and on the torque desired by the driver, valve opening and
closing times can be achieved that enable operation of the engine
especially optimally in terms of emissions and fuel consumption.
The hydraulic system of the known internal combustion engine is supplied
from a hydraulic reservoir via a high-pressure hydraulic pump. A hydraulic
cylinder supplied from the hydraulic system is connected to the tappet of
a gas exchange valve, such as an inlet or outlet valve, and leads to an
opening or closing motion of this valve.
The object of the present invention is to refine an internal combustion
engine of the type defined at the outset in such a way that it is as small
as possible in structure and can be produced as inexpensively as possible.
In an internal combustion engine of the type defined at the outset, this
object is attained in that the hydraulic pump is connected to the
lubricant system in such a way that it is lubricated by the lubricant of
the lubricant system.
SUMMARY OF THE INVENTION
The hydraulic pump is in general a heavy-duty high-pressure pump that
furnishes the requisite pressure for safe operation of the hydraulic
system. To enable this hydraulic pump to produce the required power
reliably under all operating states of the engine, complete and certain
lubrication of all the moving parts of the hydraulic pump is necessary.
Because according to the invention the lubrication of the moving parts of
the hydraulic pump is accomplished by the lubricant of the engine
lubricant system that is present anyway, it is possible to dispense with a
separate lubricant system for only the hydraulic pump. Thus the components
required for such a lubricant system, such as a special lubricant pump, a
lubricant container, and so forth, can be dispensed with. In this way, the
engine according to the invention can be made smaller. Moreover, with the
omission of the aforementioned components, expenses are saved.
Advantageous refinements of the invention are disclosed. In a first such
refinement, it is stated that as hydraulic fluid, the lubricant of the
lubricant system is used. In that case, it is accordingly possible to
dispense with a separate container for the hydraulic fluid. This further
reduces the size of the engine of the invention. Because the hydraulic
fluid and the lubricant are identical, it is furthermore possible to use
similar or even identical parts in both systems, which further reduces
both production and maintenance costs.
It is especially preferred if the hydraulic pump is connected to the
lubricant system in such a way that the pump is fed from the system, and
so the lubricant pump operates as a prefeed pump for the hydraulic system.
This refinement of the engine of the invention is preferred especially
whenever the hydraulic pump is not a self-aspirating pump. In all other
cases as well, however, this refinement of the engine of the invention
also has the advantage that the hydraulic pump can be smaller, because
since the lubricant pump furnishes a prefeed pressure, the hydraulic pump
has to have only a comparatively lesser capacity.
Alternatively, however, it can be provided that the hydraulic pump pumps a
hydraulic medium that differs from the lubricant of the lubricant system
of the engine, preferably a lower viscosity. Especially at low
temperatures, it can happen that the viscosity of the fluid typically used
as a lubricant in internal combustion engines becomes so great that both
the pumping of the hydraulic fluid by the hydraulic pump and its transport
into the hydraulic lines are impaired. If an internal combustion engine is
used under environmental conditions of this kind, it can be advantageous
if a fluid which even at very low temperatures has an extremely low
viscosity can be used as the hydraulic fluid. On the other hand, such a
fluid would be poorly suited as a lubricant for the lubricant system of
the engine, since at the high temperatures typically prevailing in the
engine, it could no longer adequately assure proper lubrication of the
moving parts of the engine.
It is also possible that a filter, in particular a fluid filter of the
lubricant system, is disposed in the fluid path between the lubricant
system and the hydraulic pump. With a fluid filter of this kind, the risk
that the hydraulic system will become plugged with deposits that
accumulate in the lubricant over time can be reduced. In this way, the
operating safety of the engine of the invention is thus enhanced. If the
fluid filter of the lubricant system, for instance a classical oil filter,
is used, then this can be done without additional components and thus also
without additional cost. However, it is also conceivable, besides the
fluid filter of the lubricant system, to use still another filter, in
order to assure the purity of the lubricant furnished to the hydraulic
system.
In another refinement, it is stated that the hydraulic system includes a
power unit, which is connected to a gas exchange valve of the engine in
such a way that this valve can be opened and/or closed by the power unit.
Such a power unit can for instance be a hydraulic cylinder, whose piston
is connected to the valve shaft of the gas exchange valve, which for
instance is an inlet or outlet valve of the engine.
With the goal of further reducing the installation space required for
installing the engine of the invention, for instance in a motor vehicle,
it is also proposed that the hydraulic pump is driven by the engine. In
this case, a separate drive mechanism, such as an electric, motor, can
thus be omitted.
The drive of the hydraulic pump by the engine can be done especially
effectively whenever the hydraulic pump is connected directly to a
crankshaft of the engine.
However, it is also possible that the hydraulic pump is connected to driven
moving parts of the engine via a gear mechanism with a variable gear
ratio. In that case, it is possible for the capacity of the hydraulic pump
to be adapted to the current operating state of the engine. This lengthens
the service life of the engine of the invention, or its hydraulic pump,
since it does not always operate at maximum capacity but instead, when
less capacity is demanded, is also driven at lesser capacity.
BRIEF DESCRIPTION OF THE DRAWINGS
Below, two exemplary embodiments of the invention are described in detail
in conjunction with the accompanying drawing. Shown in the drawing are:
FIG. 1: a schematic block circuit diagram of a first exemplary embodiment
of an internal combustion engine; and
FIG. 2: a block circuit diagram, similar to FIG. 1, of a second exemplary
embodiment of an internal combustion engine.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
An internal combustion engine is identified overall by reference numeral 10
in FIG. 1. A central region 12 of the engine 10 includes, among other
elements, an engine block, combustion chambers, pistons, and so forth. The
moving parts of the engine 10, such as pistons, crankshaft, and so forth,
are supplied with lubricant by a lubricant system 14.
The lubricant system 14 includes a lubricant pump 16, which pumps lubricant
from a lubricant sump 18 via an intake conduit 17. The lubricant pump in
the present exemplary embodiment is a typical geared pump. As the
lubricant for the moving parts of the engine 10, in the exemplary
embodiment shown in FIG. 1, a synthetic lightweight oil is used.
Via a lubricant filter 20, the lubricant is pumped through a lubricant
conduit 22 to the moving parts in the central region 12 of the engine 10.
Via a return line 24, the lubricant flows back out of the engine block 12
into the lubricant sump 18. The drive of the lubricant pump 16 is effected
via a mechanical connection, represented only symbolically in the drawing,
with driven moving parts of the engine 10. A drive via a toothed belt is
also possible, for instance.
An inlet valve 26, shown by way of example and only symbolically, serves to
supply the combustion chamber (not shown), located in the central region
12 of the engine 10, with a fuel-air mixture. The inlet valve 26
communicates with the piston (not shown) of a hydraulic cylinder 30 via a
mechanical connection 28. The hydraulic cylinder 30 is in turn part of a
hydraulic system 32, which also includes a hydraulic pump 34 that supplies
the hydraulic cylinder 30 with hydraulic fluid via a hydraulic line 36.
The hydraulic pump 34 is driven via a controllable gear mechanism 38 by a
crankshaft 40, represented only symbolically in FIG. 1, of the engine 10.
However, it is also conceivable for it to be integrated into the wheel
drive of the engine 10. Preferably, the hydraulic pump 34 is mounted at
the front or laterally on the engine block (central region 12) of the
engine 10. The hydraulic pump 34 is a high-pressure piston pump. The
hydraulic pump 34 pumps hydraulic fluid from a hydraulic container 44 via
an intake line 42. The hydraulic fluid supplied to the hydraulic cylinder
30 flows back to the hydraulic container 44 again via a return line 46.
Because of the high pressure required in the hydraulic system 32, the
hydraulic pump 34 is a heavy-duty pump, whose moving parts must be
adequately lubricated if the required power and service life are to be
achieved reliably. The hydraulic pump 34 therefore has its own lubrication
system, not identified by reference numeral in FIG. 1. The supply of
lubricant to the lubrication system of the hydraulic pump 34 is effected
from the lubricant filter 20 of the lubricant system 14 via a branch line
48 and a supplementary filter 50. However, filtration independently of the
lubricant system 14, by means of a separate fine filter (not shown) of the
lubricant delivered to the hydraulic system 32 is also possible. For the
lubrication of the moving parts of the hydraulic pump 34, the lubricant of
the lubricant system 14 is accordingly used. The return of the lubricant
is effective from the hydraulic pump 34 directly to the lubricant tub 18
via a return line 52.
The hydraulic fluid used in the engine 10 shown in FIG. 1 has a lower
viscosity than the lubricant used in this engine 10. Thus even at low
temperatures, it is assured that the pumping capacity of the hydraulic
pump 34 to the hydraulic cylinder 30 is sufficient to enable secure
actuation of the inlet valve 26. At the same time, because of the
synthetic lightweight oil used, the lubrication of the moving parts in the
engine 10, on the one hand, and in the hydraulic pump 34 on the other is
assured.
The second exemplary embodiment of an engine 10, shown in FIG. 2, will now
be described. Parts that have equivalent functions to corresponding parts
in FIG. 1 are identified by the same reference numerals and are not
explained in detail again.
Unlike the exemplary embodiment in FIG. 1, in the engine 10 shown in FIG. 2
the lubricant of the lubricant system 14 is used as the hydraulic fluid.
The lubricant pump 16 thus acts as a prefeed pump, which via the lubricant
filter 20 and the supplementary filter 50 of the hydraulic pump 34
furnishes a pilot pressure. There is no provision for a separate
lubrication system in the hydraulic pump 34. Instead, the moving parts in
the hydraulic pump 34 are lubricated by the lubricant that they pump.
In the engine 10 shown in FIG. 2, a separate container for the hydraulic
fluid is thus omitted. The lubricant or hydraulic fluid is returned from
the hydraulic cylinder 30 directly to the lubricant sump 18 via the return
line 46. Thus the lubricant sump 18 also acts as the supply reservoir for
the hydraulic system 32. The engine 10 shown in FIG. 2 is therefore even
smaller than the engine 10 shown in FIG. 1. Furthermore, fewer parts are
needed in it, so that it can also be produced and operated less
expensively. Moreover, the lubricant or hydraulic fluid is cooled by a
lubricant cooling (not shown) that is usually present anyway, which
further improves its service life. In addition, in the exemplary
embodiment shown in FIG. 2, the hydraulic pump 34 is driven directly by
the crankshaft 40 of the engine 10. In other words, power regulation via a
gear mechanism is thus dispensed with.
The foregoing relates to preferred exemplary embodiment in this invention,
it being understood that other variants and embodiments thereof are
possible within the spirit and scope of the invention, the latter being
defined by the appended claims.
*
