U.S. patent application number 09/324591 was filed with the patent office on 2001-05-24 for reverseable internal combustion engine.
Invention is credited to GANDER, HANS.
Application Number | 20010001387 09/324591 |
Document ID | / |
Family ID | 7870190 |
Filed Date | 2001-05-24 |
United States Patent
Application |
20010001387 |
Kind Code |
A1 |
GANDER, HANS |
May 24, 2001 |
REVERSEABLE INTERNAL COMBUSTION ENGINE
Abstract
In a reversible-type internal combustion engine including
electromagnetically operated gas change valves and a control unit
for controlling actuation of the gas change valves, a direction of
rotation switch is actuated to reverse engine rotation whereupon
the engine is slowed down and uncoupled from the associated drive
line and, when the engine speed falls below a predetermined value
rotation of the engine in opposite direction is initiated while the
timing of the electromagnetically controlled valves is adjusted to
the opposite direction of rotation of the internal combustion
engine.
Inventors: |
GANDER, HANS; (BAD URACH,
DE) |
Correspondence
Address: |
KLAUS J BACH & ASSOCIATES
PATENT AND TRADEMARKS
4407 TWIN OAKS LANE
MURRYSVILLE
PA
15668
|
Family ID: |
7870190 |
Appl. No.: |
09/324591 |
Filed: |
June 3, 1999 |
Current U.S.
Class: |
123/41E |
Current CPC
Class: |
F02D 27/02 20130101;
F01L 2760/002 20130101; F01L 13/02 20130101; F01L 9/20 20210101;
F01L 2201/00 20130101 |
Class at
Publication: |
123/41.00E |
International
Class: |
F01L 013/02 |
Foreign Application Data
Date |
Code |
Application Number |
Jun 6, 1998 |
DE |
198 25 411.3 |
Claims
What is claimed is:
1. A reversible reciprocating internal combustion engine including
a piston movably disposed in a cylinder, gas change valves and
electromagnetic actuators for operating said gas change valves, a
control unit for controlling actuation of said gas change valves, a
direction of movement switch for indicating to said control unit
the desired direction of rotation of said internal combustion
engine, and a direction of rotation monitor associated with said
engine for sensing the direction of rotation and a stand still of
said engine, as well as the position of the respective piston and
supplying that information to said control unit for controlling
said electromagnetic actuators.
2. A method of operating an internal combustion engine as defined
in claim 1, wherein, upon changing the position of said direction
of movement switch to reverse the direction of rotation of said
engine, the engine is uncoupled from an associated drive line, the
fuel supply and, if the engine has an external ignition system, the
ignition is interrupted and the internal combustion engine is
braked and, when the engine speed falls below a predetermined
value, the engine is restarted in the opposite direction of
rotation and than re-coupled to said drive line.
3. A method according to claim 2, wherein said internal combustion
engine is restarted by a starter which can be operated in both
directions of operation and which is energized depending on a
control signal of the control unit.
4. A method according to claim 2, wherein said internal combustion
engine is started in the opposite direction of rotation by setting
the ignition timing of an external ignition system to early
ignition when the engine speed has dropped below a predetermined
value.
5. A method according to claim 2, wherein said engine is slowed
down by a brake associated with said engine before reverse engine
rotation is initiated.
6. A method according to claim 2, wherein said engine is slowed
down by an electric generator before reverse engine rotation is
initiated.
7. A method according to claim 2, wherein said engine is slowed
down by operating said valve actuators in a braking mode.
8. A method according to claim 2, wherein reversing of said engine
operation is permitted only at predetermined transmission ratios.
Description
BACKGROUND OF THE INVENTION
[0001] The invention relates to a reversible reciprocating internal
combustion engine with intake and exhaust valves.
[0002] Reciprocating internal combustion engines are generally
operated only in one direction of rotation. If in a certain
application, for example, in motor vehicles, motive power in both
direction of rotation is needed, the internal combustion engine is
generally provided with a reversing transmission, which can be
shifted with interruption of the transmission of power or under
load.
[0003] DE 26 34 916 C2 discloses a reversible piston-type internal
combustion engine, which is capable of operating in both directions
of rotation. To change its direction of rotation, the internal
combustion engine is shut down and stopped and the timing of the
intake and exhaust valves is changed for the new direction of
rotation by axially moving a camshaft operating the valves so that
cams specifically provided for the new direction of operation
become effective. In internal combustion engines with external
ignition also the ignition timing must be adapted to the new
direction of rotation. Reversible internal combustion engines are
used especially in connection with ships, particularly ships having
low-speed Diesel engines, which drive a ship propeller directly
without intermediate transmission. Such reversible arrangements
have been successfully used to avoid the need for transmissions and
reversing transmissions in drives transmitting high torques and
high power. In these application, there is generally sufficient
time for reversing the direction of engine rotation. Also, such
piston type internal combustion engine can be slowed down and
restarted relatively rapidly by pressurized air.
[0004] U.S. Pat. No. 3,981,278 discloses an arrangement for the
protection of reversible piston type internal combustion engines
during rotation reversal of the engine. In this case, the engine
speed and the direction of rotation at the time the reversing
operation is initiated are determined.
[0005] In U.S. Pat. No. 5,036,802, a method, whereby the direction
of rotation of a two-cycle engine with external ignition can be
reversed. During reversal, the ignition is interrupted, the speed
of the crankshaft is continuously reduced and, at the same time,
monitored. When the speed falls below a predetermined value and
before the engine is at a standstill, the ignition is reactivated,
but with a sufficiently large ignition angle before the top dead
center position of the respective piston that the forces generated
are sufficiently large to drive the piston back down before it
reaches the top dead center position. Then the engine rotates in
the opposite direction and the ignition is set to a normal value
corresponding to the new direction of rotation. Such a reversal of
engine rotation is to be used in connection with snowmobiles, which
change their direction of movement relatively frequently. The
reversal of the direction of engine rotation is performed
automatically when an operating switch is activated. The internal
combustion engine does not need to be stopped for that purpose.
[0006] However, the known reversal arrangements and methods are not
suitable for motor vehicles with valve controlled reciprocating
internal combustion engines.
[0007] Electromagnetic actuators for operating gas change (intake
and exhaust) valves are generally known for example from DE 39 20
976 A1. They include generally two operating magnets, that is a
valve opening magnet and a valve-closing magnet between whose pole
faces an armature is arranged so as to be movable coaxially with a
valve axis. The armature acts directly or indirectly on a valve
shaft of the gas change valve by way of an armature plunger.
Actuators operating in accordance with the principle of a mass
oscillator include a pre-tensioned spring mechanism engaging the
armature. As spring mechanism generally two pre-tensioned
compression springs are used, that is, an upper valve spring which
serves as a valve opening spring and which generates a force in
valve opening direction and a lower valve spring which serves as a
valve closing spring and generates a force in the valve closing
direction. If the magnets are not energized, the armature is held
by the valve springs in an equilibrium position between the
magnets. With such actuators gas change valves can be controlled
individually as desired.
[0008] It is the object of the present invention to simplify the
reversal of rotation of reciprocating internal combustion engines
and to make such arrangements suitable for use in motor vehicles
with valve controlled engines.
SUMMARY OF THE INVENTION
[0009] In a reversible-type internal combustion engine including
electromagnetically operated gas change valves and a control unit
for controlling actuation of the gas change valves, a direction of
rotation switch is actuated to reverse engine rotation whereupon
the engine is slowed down and uncoupled from the associated drive
line and, when the engine speed falls below a predetermined value,
rotation of the engine in opposite direction is initiated while the
timing of the electromagnetically controlled valves is adjusted to
the opposite direction of rotation of the internal combustion
engine.
[0010] With this arrangement, the timing of the gas change valves
can be adjusted to a new direction of operation rapidly and in a
simple manner.
[0011] The reversing procedure required herefor is preferably
performed by a control unit which monitors the required parameters
by way of sensors and processes them to provide the respective
control signals for the actuators, a starter and, if needed, an
ignition system and a brake. After interruption of the power
transmission by way of a clutch, the fuel supply and, if present,
the external ignition are interrupted. The piston type internal
combustion engine is then slowed down by internal friction forces
until the engine speed has fallen below a value at which the actual
reversal can occur. At that point the piston-type internal
combustion engine can be started in the opposite direction of
rotation. In order to accelerate this process, it is advantageous
to provide the engine additionally with a primary brake, for
example, a friction brake, a primary retarder, an exhaust gas brake
or similar system. Similar results can be achieved according to an
embodiment of the invention also in that the actuators for slowing
down the piston-type internal combustion engine are placed into a
braking mode. To this end, the timing for the gas change valves is
so changed that the compression losses and gas change losses of the
internal combustion engine are as large as possible.
[0012] The piston type internal combustion engine may also be
slowed down by the vehicle by interrupting the drive train only
when the predetermined engine speed is below the predetermined
value. However, since the smaller mass of the engine alone can be
braked faster than the larger mass of the vehicle, the time
difference can be utilized for the reversing process so that the
drive train connection can be re-established without delay as soon
as the vehicle has reached the acceptable speed.
[0013] Further advantages of the invention will become apparent
from the following description of an embodiment of the invention on
the basis of the accompanying drawings. The description and the
claims cover various features in a combination. The expert will
consider the features individually and may combine them in
additional embodiments.
BRIEF DESCRIPTION OF THE DRAWINGS
[0014] FIG. 1 is a schematic cross-sectional view of a
reciprocating internal combustion engine.
DESCRIPTION OF A PREFERRED EMBODIMENT
[0015] A piston-type internal combustion engine 1 comprises a
cylinder block 3 including a cylinder 2. A piston 4 is movably
disposed in the cylinder 2 and is connected to a crankshaft 6 by
way of a connecting rod 5.
[0016] The cylinders 2 are closed by a cylinder head 8, which
includes for each cylinder at least two gas change valves 19, 20,
one intake valve and one exhaust valve, which control the
respective gas flow passages. The gas change valves 19, 20 are
operated by electromagnetic actuators 23 and 24, which include each
an upper closing magnet 25, 26 and a lower opening magnet 27, 28,
which act on the gas change valves 19, 20 by way of an armature 33,
34 disposed between the magnets 25, 26 and 27, 28. The actuators
23, 24 are aided by spring systems which each include a closing
spring 29, 30 and an opening spring 31, 32 and which act on the gas
change valve in accordance with a spring-mass oscillator.
[0017] The piston-type internal combustion engine 1 can be operated
in both directions of rotation 7 by reversal of its direction of
rotation. For this purpose, a control unit 10 is provided which is
connected to a direction of rotation and standstill monitor 9 by a
signal line 14, to a direction of driving switch 11 with a position
v for forward and a position r for reverse by a signal line 12, and
with a vehicle speed sensor, which is not shown, by a signal line
15. Additional sensors, which are suitable for a safe control of
the reversing procedure may be connected to the control unit
10.
[0018] The control unit 10, which may include a microprocessor
processes the signals supplied thereto on the basis of
characteristic values, characteristic curves and/or performance
graphs. The control unit forms output signals, which control the
actuators 23, 24 by way of the control lines 16, 17, the ignition
system, if present, by way of a control line 13. Another control
line 37 is provided for a brake 36. A fuel flow measuring device,
which is also controlled by the control unit 10, is not shown in
the figure as it is preferably part of the electronic engine
control system.
[0019] When the direction of driving switch 11 is operated, the
control unit 10 interrupts the fuel supply to the engine 1 and the
drive line 39 to the vehicle suitably by actuating a clutch 40
(shown schematically). In an engine with an external ignition
system, also the power supply to the spark plug 35 is interrupted.
When the rotational speed of the crankshaft 6 falls below a
predetermined value, which is sensed by the direction of rotation
and stand-still monitor 9 and signaled to the control unit 10 and
which is interpreted by the monitor 9 as stand-still of the engine,
the actuators 23, 24 and the spark plug 35 are controlled in
accordance with a new cycle and the starter 38 is energized to
re-start the internal combustion engine in the new direction of
rotation. Subsequently, the drive connection between the internal
combustion engine 1 and the vehicle is re-established. Internal
combustion engines with eternal ignition may be started in the new
direction of rotation without the use of a starter 38 by setting
the external ignition to an early ignition point when the engine
speed falls below a predetermined value.
[0020] In order to accelerate the procedure, the internal
combustion engine 1 may be slowed down by an additional brake 36.
The brake 36 may be a primary retarder, an exhaust gas brake or a
friction brake. Furthermore, a generator can be utilized to brake
down the engine, wherein the braking force may be controlled by the
power consumption of the generator. Instead of the brake 36, or in
combination therewith, the actuators 23, 24 may be operated in a
braking mode. In this mode, the gas change valves are so controlled
that the internal combustion engine has high internal losses. This
can be achieved, for example, in that the intake valves and exhaust
valves are opened very late so that, during the intake stroke, a
high vacuum is generated in the cylinder and the piston operates
against a high compression pressure during the exhaust stroke. With
the internal combustion engine 1 according to the invention, a
reversing gear set in the transmission can be eliminated. The
change-over from forward to reverse operation is fully automated.
It is also possible to operate the vehicle in forward or in reverse
at all the transmission ratios. However, it is preferred to limit
reverse operation to transmission ratios, which insure safe reverse
operation.
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