MOTEUR ALTERNATIF

RECIPROCATING ENGINE

Abrégé anglais

RECIPROCATING ENGINE
Abstract of the disclosure
A reciprocating engine has a disk flywheel on the
crankshaft for smoothing the unevenness of the torque.
A second flywheel, mounted in a freely rotatable
manner on the crankshaft, is coupled by a friction
clutch to the disk flywheel. The clutch is operated
by an actuator controlled by a control device which
processes signals from sensors. In steady state
operation of the engine in the low speed range the
second flywheel is engaged. Upon acceleration and in
the range of high speeds the second flywheel is
disengaged. The engine thus runs smoothly at low
speed. However, it accelerates faster than a
comparable conventional engine and has a better
braking action. In driving operations in a vehicle
after braking, part of the kinetic energy of the
flywheel can be used to accelerate the vehicle.

Revendications

6
Claims
The embodiment of the invention in which an exclusive
property or privilege is claimed is defined as
follows:
1 - A reciprocating engine having a crank drive and a
flywheel on the crank drive for smoothing the degree
of unevenness of the torque produced, wherein the mass
moment of inertia of the crank drive is selectively
minimized during nonsteady state operation and one or
more additional flywheels are provided that are
connectable in a controllable manner to the crank
drive.
2 - A reciprocating engine in accordance with claim 1,
wherein the additional flywheels are freely rotatable
on the crank drive and can be connected to the crank
drive by a controllable clutch.
3 - A reciprocating engine in accordance with claim 2,
wherein the controllable clutch is a friction clutch
which is operated via an actuator.
4 - A reciprocating engine in accordance with claim 3,
wherein the actuator of the controllable clutch is
operationally connected to a control device which, in
response to signals from sensors for the engine speed,
a change in the engine speed, a load for the engine, a
change in the load and the actual load condition,
generates a signal for the actuator for controlling
the clutch.

Description

` -~` 2 ~
G-11812
RECIPROCATING ENGINE
Technical field
The invention pertains to a reciprocating engine with
a flywheel mass arranged on the crankshaft for
smoothing the torque produced.
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Backqround
Reciprocating engines, especially those with few
cylinders, have an uneven application of torque
because of the successively occurring operating cycles
of the pistons. This degree of unevenness is known to
diminish with increasing mass moment of inertia of the
crank drive. Thus in reciprocating engines it is
customary to connect the crankshaft directly to a
flywheel mass. The increase in the mass moment of
inertia, however, has an unfavorable effect on the
dynamic behavior of the engine, since energy must be
expended during changes in speed in order to alter the
state of motion of the rotating mass. The angular
acceleration of the crank drive that can be achieved
for the same application of torque is inversely
proportional to its mass moment of inertia. The
requirements for higher engine dynamics and a high
degree of evenness are thus conflicting. The design
of the conventional reciprocating engine therefore has
the character of a compromise in the dimensions of the
flywheel masses.

211~ 6~6
Summary of the Invention
A purpose of the present invention is to allow a
reciproca~ing engine, even one with a few cylinders,
to operate in steady state operation (and especially
in the range of low rotational speeds) with a high
degree of evenness, while in nonsteady state operation
(i.e. in the case of changes in rotational speed) the
crank drive exhibits only low inertia.
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This problem is accomplished according to the
invention by providing that the mass moment of inertia
of the crank drive is minimized during nonsteady state
operation, while for low speed steady state operation,
one or more additional flywheels can be connected in a
controllable manner to the crank drive. The
additional flywheels are preferably mounted in a
freely rotatable manner on the crankshaft and are
connected to the crankshaft by a controllable clutch.
A friction clutch operated via an actuator is
advantageously employed as the controllable clutch.
The actuator of the controllable clutch is
operationally connected to a control device which
generates a signal for actuators to engage/disengage
the clutch as a function of the engine speed, a change
in the engine speed, the rated load on the engine, a
change in the load and the actual load conditions.

211~ 63.i
Brief Drawinq Description
An example of the invention is described in detail
with reference to a single schematic drawing figure.
Detailed Descri~tion
A crankshaft 1 of a reciprocating engine is connected
in a nonrotatable manner to a disk flywheel 2. On the
crankshaft 1 near the disk flywheel 2 an additional
flywheel 3 is mounted in a rotatable manner. The disk
flywheel 2 and the flywheel 3 can be connected by a
friction clutch 4 acting between them.
The clutch 4 is designed in such a way that the
frictional connection commences smoothly. The clutch
4 is operated via an actuator 5 which is designed as a
hydraulic or electric servomotor. The actuator 5 is
modulated by a signal 6 generated by a control device
7 which via sensors 8, 9, 10, 11, 12 receives as input
the speed n of the reciprocating engine; a change in
the engine speed dn/dt; the assigned load for the
reciprocating éngine, e.g. in the form of the opening
angle of the throttle valve xDK; a change in the
assigned load for the reciprocating engine dxDK/dt;
and the actual load condition, e.g. in the form of a
value proportional to the air throughput of the
reciprocating engine, and relates them to one another.
Upon the starting of th~ engine the additional
flywheel 3 is disengaged from the disk flywheel 2.
Therefore the starter motor does not have to

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21-l ~63~
accelerate the additional flywheel 3, and the starting
power required is lower. During operation at
approximately uniform, low speeds n, the additional
flywheel 3, is coupled to the disk flywheel 2, and the ~ `
greater flywheel mass compensates for the unevenness
of the angular velocity occurring on the crankshaft 1.
At high engine speeds n, additional flywheel 3 is
disengaged since in this case the smaller flywheel
mass formed solely by the crank drive and the disk
flywheel 2 is sufficient for adequate compensation of
the degree on unevenness.
If positive acceleration of the reciprocating engine
dn/dt beyond a certain threshold value is detected by
the sensor 9, the clutch 4 is disengaged. The
reciprocating engine thus accelerates with a low mass
moment of inertia. Once this nonsteady state process
is completed, then the clutch 4 is caused to engage so
that the additional flywheel 3 is accelerated by the
frictional moment of the clutch 4 to the speed of the
crankshaft 1. Smooth engagement is possible through a
choice of a high slip on the clutch 4. This process
is ideally conducted during vehicle operation after a
desired traveling speed is reached since then the
25 . total inertial mass of the vehicle acts back on the
flywheel 3 to be accelerated.
If a negative acceleration dn/dt of the crank drive is
recognized by the sensor 9, then two controlled
variants are possible, e.g. as a function of the
traveling state of a vehicle. In the first case the
additional flywheel 3 remains connected to the

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crankshaft 1 and the disk flywheel 2 and the energy of
motion of the now greater flywheel mass is utilized to
overcome driving resistances. In a second case, i.e.
during the braking of a vehicle, the flywheel 3 is
disengaged from the crank drive. As a result the
braking effect of the transmission is increased. The
energy inherent in the flywheel 3 traveling at a
higher speed can be utilized again in a subsequent
acceleration by engaging the clutch 4 until the speed
between the flywheel 3 and crankshaft 1 is equalized.
The choice between the two described cases is easily
made by the sending of the correct signals from the
sensors 8 to 12 to the control device 7.
The invention also responds when other signals are
sent to the control device 7, e.g., the signal of the
speed of a vehicle.
Similarly, according to the invention several
additional flywheel masses can be successively coupled
to the crankshaft of a reciprocating engine or
uncoupled from it in order to make possible a more
finely graduated adaptation of the active flywhee.l
mass to the requirements in each case.

Dessin représentatif