Internal-combustion engines – Cooling – With jacketed head and/or cylinder
Reexamination Certificate
1999-06-03
2001-05-29
Kamen, Noah P. (Department: 3747)
Internal-combustion engines
Cooling
With jacketed head and/or cylinder
Reexamination Certificate
active
06237546
ABSTRACT:
BACKGROUND OF THE INVENTION
The invention relates to a reversible reciprocating internal combustion engine with intake and exhaust valves.
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.
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 engines can be slowed down and restarted relatively rapidly by pressurized air.
U.S. Pat. No. 39 81 278 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.
In U.S. Pat. No. 5 036 802, a method is disclosed, 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.
However, the known reversal arrangements and methods are not suitable for motor vehicles with valve controlled reciprocating internal combustion engines.
Electromagnetic actuators for operating gas change (intake and exhaust) valves are generally known for example from DE 39 20 976 Al. 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 shaft. 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.
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
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.
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.
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.
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.
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Bach Klaus J.
Daimler-Chrysler AG
Kamen Noah P.
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