Internal combustion engine

An internal combustion engine driven by a gaseous fuel, with quantity regulation in a lower load range and quality regulation in an upper load range. A gas pressure regulator is provided for controlling a gas flow to an air-gas mixer, with a throttle valve actuatable by an accelerator pedal being arranged in an intake line downstream of the air-gas mixer, whereby the gas pressure regulator is movable in a closing direction through a control line, by a diaphragm by vacuum prevailing in the intake line in a vicinity of the throttle valve. A control valve, influenced by the accelerator in the quality control range, is disposed in a control line. The control line branches off the intake line upstream of the throttle valve or off the air-gas mixer. A throughput or through-flow cross section in the control valve decreases with increasing loads in a direct relationship to a position of the accelerator until the control valve closes at full load. The control line between the control valve and gas pressure regulator is connected to outside air through a fixed throttle.

The present invention relates to an internal combustion engine and, more 
particularly, to an internal combustion engine driven by a gaseous fuel, 
with the engine having a fuel quantity regulation in a lower load range of 
operation and a quality fuel regulation in an upper load range, and with a 
gas pressure regulator for a gas flow to an air-gas mixer, and with a 
throttle valve, actuatable by an accelerator or gas pedal being disposed 
in an intake line downstream of the air-gas mixer whereby the gas pressure 
regulator is movable in a closing direction through a control line by way 
of a diaphragm acted upon by a vacuum prevailing in an intake line in a 
vicinity of the throttle valve, as well as a control valve disposed in the 
control line and being influenced by the accelerator or gas pedal in the 
quality regulation or control range of operation of the engine. 
An internal combustion engine of the aforementioned type is disclosed in, 
for example, German Patent Application No. P 29 48 449.9-13, wherein a 
magnitude of a vacuum which acts upon the diaphragm of the gas pressure 
regulator through the control line depends only on a position of the 
accelerator or gas pedal. The vacuum in the intake line downstream of the 
throttle valve serves only as a vacuum source and the magnitude of this 
vacuum has no effect upon the magnitude of the vacuum in the gas pressure 
regulator. A disadvantage of this proposed construction resides in the 
fact that a volume of gaseous fuel supplied is regulated in the quality 
control range only by the load of the engine and not by the rotational 
speed of the internal combustion engine. 
The aim underlying the present invention essentially resides in providing 
an internal combustion engine having an improved gas supply regulation 
especially in a quality control range, as well as an improved combustion 
process in the engine. 
In accordance with advantageous features of the present invention, an 
internal combustion engine of the aforementioned type is provided wherein 
the control line branches off an intake line upstream of the throttle 
valve or off the air-gas mixture. The through flow cross section in the 
control valve decreases with increasing loads in a direct relationship to 
the position of the accelerator or gas pedal until it closes at full load. 
Additionally, the control line between the control valve and gas pressure 
regulator is connected with outside air through a fixed throttle. 
By virtue of the features of the present invention, a vacuum acting upon 
the gas pressure regulator is a direct function of the vacuum in the 
intake line upstream of the throttle valve and thus is a function of the 
rotational speed of the internal combustion engine. Moreover, the vacuum 
is modified in the quality control range in the regulator valve as a 
direct function of the accelerator or gas pedal position whereby the 
influence of the load of the internal combustion engine on the gas supply 
in this control range is ensured. Moreover, a connecting of the control 
line through a fixed throttle with the outside air affects the absolute 
level of the vacuum acting on the gas pressure regulator diaphragm without 
influencing its dependence upon the rotational speed and load range of the 
engine. 
In order to ensure in a simple fashion that the control valve is actuated 
by the accelerator or gas pedal only in the quality control range, in 
accordance with the present invention, a slider is provided having a free 
travel or idle path in the quality control range, with the slider being 
disposed in a rod between the accelerator or gas pedal and the control 
valve. 
In accordance with further features of the present invention, a 
three/two-way valve is disposed in the control line between the control 
valve and gas pressure regulator, through which valve the gas pressure 
regulator is connectible with the intake line downstream of the throttle 
valve or a vacuum tank. By virtue of these features of the present 
invention, it is ensured that an increased vacuum may act upon the gas 
pressure regulator in certain cases such as, for example, when the 
internal combustion engine is shut off or pushed thereby interrupting the 
fuel feed. 
In order to provide an improvement in the combustion process by adjusting 
an ignition timing to the engine to the load of the engine in the quality 
control range, according to the present invention, a drive lever having a 
rod engages between the slider and control valve following a certain 
amount of free travel, with the drive lever being connected with a device 
for adjusting the ignition timing in a distributor. With the rod coupled 
to the accelerator or gas pedal, it is possible to adjust the ignition 
timing in the distributor, with a conventional dependence of the ignition 
point setting upon the vacuum not being applicable in the quality control 
range of operation of the engine. 
Advantageously, in accordance with further features of the present 
invention, a stop is provided for the drive lever, with the position being 
dependent upon a vacuum in the diaphragm chamber. By virtue of these 
features, it is ensured that an adjustment of the ignition timing in an 
early range can only take place when a sufficiently high vacuum prevails 
in the diaphragm chamber thereby eliminating a knocking caused by the 
combustion process in the internal combustion engine. 
Advantageously, according to the present invention, a connection is 
provided between a rod part that leads to the accelerator or gas pedal and 
rod parts which lead to the throttle valve and control valve, with the 
connection being overloadable and ineffective in case of malfunction such 
as excessively high engine rotational speed. By virtue of this 
arrangement, there is a clear relationship between the various parts of 
the rods between the accelerator or gas pedal, throttle valve, and 
regulator valve; however, in case of certain malfunctions, the fuel supply 
to the internal combustion engine may be interrupted without a positioning 
of the accelerator or gas pedal having any influence. 
Accordingly, it is an object of the present invention to provide an 
internal combustion engine driven by a gaseous fuel which avoids, by 
simple means, shortcomings and disadvantages encountered in the prior art. 
Another object of the present invention resides in providing an internal 
combustion engine driven by a gaseous fuel which improves the regulation 
of a gas supply especially in a quality control range operation of the 
engine. 
Yet another object of the present invention resides in providing an 
internal combustion engine driven by a gaseous fuel which engine has an 
improved combustion process. 
A still further object of the present invention resides in providing an 
internal combustion engine driven by a gaseous fuel which functions 
realiably under all operating or load conditions. 
A still further object of the present invention resides in providing an 
internal combustion engine driven by a gaseous fuel which is simple in 
construction and therefore relatively inexpensive to manufacture.

Referring now to the drawings wherein like reference numerals are used 
throughout the various views to designate like parts and, more 
particularly, to FIG. 1, according to this figure, an air intake line 2 of 
an internal combustion engine (not shown) is connected to an air filter 1, 
with an air-gas mixer or distributor 3 being disposed in the intake line 
2. The air-gas mixer 3 is connected by way of a line 4 with a gas pressure 
regulator generally designated by the reference numeral 5. The gas 
pressure regulator includes a diaphragm 7 and a spring 6 acting on the 
diaphragm 7. A vacuum in the line 4 operates against the biasing force of 
the spring 6 and moves the diaphragm 7 in an opening direction. The 
diaphragm 7 controls, by way of a rod 8, a gas feed from a converter or 
evaporator (not shown) through a line 9 to the line 4. 
A throttle valve 10 is disposed in the intake line 2 at a position 
downstream of the air-gas mixer or distributor 3. An idle stop 11 and 
fully open stop 12 for the throttle valve 10 are disposed in the intake 
line 2. The throttle valve 10 is actuated through a rod of linkage system 
13, 14, 15, by an accelerator or gas pedal designated by the arrow 16. A 
sleeve 17 is incorporated or interposed between the rod or linkage parts 
14, 15. The later linkage system provides a rigid connection so long as 
the throttle valve moves between the idle stop 11 and fully open stop 12; 
however, the rod or linkage system may be subjected to an excess pressure 
when the throttle valve 10 is against the fully open stop 12 so as to 
result in a limited relative displacement between the rod or linkage parts 
14, 15. A connection between the rod or linkage parts 13, 14 is effected 
by a spring 18 which, in a normal case, acts like a rigid connection. 
The rod or linkage part 14 is firmly connected to an additional rod or 
linkage part 19. The additional rod or linkage part 19 abuts or is 
connected with a further rod or linkage part 21, connected with a 
regulator valve 22, through a slider 20. The regulator valve 22 includes a 
conical throttle element 23, with the throttle element 23 fitting into the 
opening 24 in the regulator valve 22. A cross section of the opening 24 
changes as a result of a lengthwise or longitudinal displacement of the 
throttle element 23 effected by a displacement of the rod or linkage part 
21. The opening 24 is connected by a control line 25 to the air gas mixer 
3 and by a control line 26 with the gas pressure regulator 5. The control 
line 26 terminates in a chamber 27 which is delimited or defined by the 
diaphragm 7 of the gas pressure regulator 5 so that a vacuum prevailing in 
the chamber 27 attempts to effect a movement of the diaphragm 6 which will 
reduce the gas supply. The control line 26 is connected or communicates 
with outside air through a fixed throttle 28 and a small air filter 29. 
When the internal combustion engine is running, a movement of the 
accelerator or gas pedal 16 from an idle position moves the throttle valve 
10 from the idle stop 11 to the fully open stop 12 by the rigidly 
connected rod or linkage parts 13, 14, 15. The rod or linkage part 19 
executes an idle movement which is not transmitted to the regulator valve 
22, by virtue of the slider 20 so that the cross section of the opening 24 
remains the same. A volume of gas supplied depends only upon the vacuum in 
the air-gas mixer 3 transmitted through the control lines 25, 26 to the 
gas pressure regulator 5 in addition to an influence of the vacuum in the 
line 4, which vacuum is a function of a load and rotational speed of the 
engine so that a pure fuel quantity control takes place in this load or 
operational range of the engine. 
When the accelerator or gas pedal 16 is moved further toward a full load 
position, the sleeve or pull over element 17 is displaced or pulled over 
because the throttle valve 10 is abutted against the fully open stop 12 
and the rod or linkage part 14 executes a free travel while, on the other 
hand, the rod parts or links 19 and 21, after bridging the slider 20 are 
firmly connected together so that the throttle element 23 reduces the 
opening 24. The RPM or rotational speed-dependent and load-independent 
vacuum in the air-gas mixer 3 thus acts after a load-dependent 
modification in the regulator valve 22 in the gas pressure regulator 5. 
Therefore, in this load or operational range of the engine, a pure quality 
regulation takes place with a low-independent air throughflow through the 
air-gas mixer 3. At a full load, the opening 24 is closed by the throttle 
element 23 and outside air pressure prevails in the control line 26 due to 
the connection through the fixed throttle 28 and the maximum quantity of 
gas is supplied. 
A three/two-way valve generally designated by the reference numeral 30 is 
incorporated in the control line 26. The valve 30 is adapted to connect 
the gas pressure regulator 5 through line 31 with the intake line 2 at a 
position downstream of the throttle valve 10 or with a vacuum tank 32 so 
as to permit a gas supply to be interrupted when, for example, pushing the 
engine. 
A drive lever 33 is movable by the rod or linkage part 21. The drive lever 
33 is connected by a rod or linkage part generally designated by the 
reference numeral 34 and a slider 35 with a means for changing an ignition 
timing of a distributor 36. 
As shown most clearly in FIG. 2, the rod 34 is provided with two stops 37, 
38 which define or limit the ignition timing adjustment. The stop 37 is a 
partial load stop and is formed by an inner end of a hollow threaded pin 
39. The hollow threaded pin 39 is threadably inserted into a tube 40 
connected to the distributor 36. A rod 41 is provided with a bead 42 which 
is adapted to strike or abut the partial load stop 37. The stop 38 is a 
full load stop and is formed by an outer end of the hollow threaded pin 
39. A nut 43 threaded on the rod 41 is adapted to strike or abut against 
the full load stop 38. The partial load stop 37 and full load stop 38 may 
be continuously adjusted by simply turning the threaded pin 39 and the nut 
43. 
In order to impede or prevent an advancement of the ignition timing in the 
event of a malfunction, as shown in FIG. 1, a stop 53 is provided for 
controlling or stopping a movement of the drive lever 33. The position of 
the stop 53 is controlled by a vacuum in the control line 26 and therefore 
in the pressure chamber 27 through a line 54 and a servo motor 55. This 
arrangement ensures that the ignition timing will only be advanced when 
there is a sufficiently high vacuum in the pressure chamber 27 thereby 
eliminating the possibility of the internal combustion engine being 
damaged by excessive knocking in the combustion process. 
In special situations such as, for example, when the internal combustion 
engine is operating at an excessive rotational speed, the connection 
between the rod or linkage part 13 and rod or linkage parts 14 and 19 may 
be rendered ineffective whereby a servo motor 44 acting on dog 45 moves 
the rod or linkage parts 14 and 19 against the force of the spring 18 to 
an idle position. If the servo motor 44 fails, a spring 46 may be provided 
so as to accomplish this task of moving the rod or linkage parts 14, 19 to 
the idle position. The servo motor 44 may be controlled by an electronic 
control means 47, of conventional construction, in which the rotational 
speed and other operating parameters of the internal combustion engine, 
fed from suitable sensors or detectors (not shown) are compared with 
predetermined set values for the sensed parameters. 
As shown most clearly in FIG. 3, the connection between the rod or linkage 
parts 13, 14, 19 as well as the protection against excessive rotational 
speed may be accomplished in other ways such as, for example, electrically 
or pneumatically. More particularly, with a pneumatic arrangement, the 
accelerator or gas pedal 16 is connected, by way of a rod 13, to a piston 
48 disposed in a cylinder 49, with the accelerator or gas pedal 16 by way 
of the rod 13 controlling the position of the piston 48. The rod or 
linkage parts 14 and 19 are connected to the cylinder 49. 
In a normal operation, the cylinder 49 is filled with a liquid or 
compressed air so that the piston 48 and cylinder 49 are rigidly connected 
together. In the event of a malfunction, the cylinder 49 is emptied 
through a line 50 so that the rod or linkage parts 14 and 19 are moved to 
an idle position by a spring 51 independently of the position of the 
accelerator or gas pedal 16. The line 50 is connected to an 
electro-pneumatic or an electro-hydraulic control unit 52, of conventional 
construction, into which the rotational speed and other operating 
characteristics or parameters of the internal combustion engine are fed 
and compared with predetermined set values for the characteristics or 
parameters. 
While we have shown and described only two embodiments in accordance with 
the present invention, it is understood that the same is not limited 
thereto but is susceptible of numerous changes and modifications as known 
to one having ordinary skill in the art and we therefore do not wish to be 
limited to the details shown and described herein, but intend to cover all 
such modifications as are encompassed by the scope of the appended claims.