Heat engine speed governor

A heat engine speed governor, includes an electric motor of unidirectional rotation kinematically connected to an input shaft of a differential mechanism, the other input shaft of which is rotated by a heat engine, while the output shaft is kinematically connected to a fuel dosing device of the heat engine. In the channel for controlling the rotational speed of the electric motor, the speed meter measuring the rotational speed of the heat engine is connected to the input of a comparison unit whose input is connected to the output of a program forming unit forming a program of controlling the electric motor speed. The output of the comparison unit is connected to the input of an integrator whose output is connected to the input of the unit forming a control signal. The setting input of the control signal forming unit is connected to the output of the program forming unit while the output is electrically connected to the electric motor. Connected to the input of the control signal forming unit is a channel for correction of the speed of the electric motor under transient conditions following the speed of the heat engine.

TECHNICAL FIELD 
The present invention relates to heat engines and, more particularly, the 
invention relates to a heat engine speed governor. 
DESCRIPTION OF THE PRIOR ART 
The most important technical characteristics of a machine with a heat 
engine are reliability, output capacity, low fuel consumption, quality of 
performing the technological operations by the machine, content of smoke 
in the exhaust and toxicity of the flue gases under transient operating 
conditions, amount of operations performed by the driver and a force 
applied to the accelerator pedal of the vehicle, fitness of the heat 
engine to different kinds of fuel, high mountain conditions, low ambient 
temperatures and other parameters. The above characteristics largely 
depend on the properties of the speed governor of the heat engine. 
The present-day heat engines, in particular tractor and automotive engines, 
are equipped mainly with mechanical governors having a centrifugal-type 
sensing element. In order to improve the automatic control of the vehicle, 
these governors are equipped with special-purpose electric drives 
including a reversible electric motor for controlling the speed of the 
heat engine, an electric motor for limiting the fuel supply, an electric 
magnet device for increasing the fuel supply when starting the heat 
engine, and an electrohydraulic valve to cut off the fuel supply when 
stopping the heat engine. 
The prior art mechanical, hydraulic and pneumatic governors do not meet the 
permanently increasing requirements to the level of automation of 
controlling the fuel supply of a heat engine. Furthermore, the modern 
governors must maintain a preset speed of the heat engine with a high 
accuracy under steady-state conditions (with permissible tolerance within 
.+-.0.25% of the rated value), which cannot be maintained by means of the 
above governors. Therefore, studies are being conducted to develop an 
electrical governor capable of improving the automatic control of a heat 
engine and providing a high accuracy of maintaining a preset speed of the 
heat engine due to flexible adjustment of the control elements of the 
governor and application of corrective feedback. The static, dynamic and 
functional characteristics of the automatic speed control system of a heat 
engine are set by forming a program of control of an actuating electric 
drive. The type of this program depends on the application of the machine 
unit with a heat engine, nature of the machine load and some other 
technological factors. 
Known in the art is a large group of electrical governors for controlling 
the speed of a heat engine based on a positioning electric drive having 
alternating direction of rotation of the armature comprising an electric 
drive kinematically connected to a fuel dosing device and electrically 
connected to a unit comparing the real speed of the heat engine with a 
preset speed, a unit for forming the program for controlling the heat 
engine, and a unit for forming a program for controlling the electric 
drive. The electric drive in these governors may be made in the form of a 
moment electric motor or a proportional electric magnet (materials of the 
symposium of "Robert Bosch" Company BRD, published on May 16,1984 
(Moscow): report by K. Zimmerman "Diesel Equipment of the "Bosch" Company" 
(FIGS. 17 and 22), or in the form of a step motor (materials of the 
"Fridman-Mayer" symposium, Austria, published on Apr. 16, 1984 (Lenigrad): 
report by F. Pashke "Development of Electronic Governor", pp. 4-5, FIG. 
17). 
Later on the entire group of positioning electric drives providing 
alternating rotation of the armature in the process of control will 
conventionally be called electric motors. 
The process of controlling the speed of a heat engine having electric 
governors of this group is effected as follows. Under steady state 
conditions, when the heat engine speed is equal to a required speed, no 
control signal is present at the output of the unit comparing these 
speeds. As a result, the electric motor armature and the fuel dosing 
device are in an equilibrium state corresponding to the steady-state load 
of the heat engine. As soon as the speed of th heat engine deviates from a 
preset value, e.g. following a change of the load, the comparison unit 
produces a signal proportional to the difference of the compared speeds. 
This signal is fed to the electric motor through the control unit forming 
unit. As a result, the fuel dosing device occupies such a new postion, in 
which the real and required rotational speeds of the heat engine become 
equal to each other. 
The governors with a positioning electric drive are featured by a low level 
of utilization of their useful power. This is due to the fact that under 
steady-state operating conditions of the heat engine, when the fuel dosing 
device and the associated electric motor armature are stationary, the 
electric motor operates in a mode close to the braked state of its 
armature, which is characterized by low efficiency. Therefore, to maintain 
the rotational speed of the heat engine with a high accuracy, the input 
power of the electric motor must be increased. 
In the above described electrical governors with a positioning electric 
drive the heat engine speed meter, the electric circuits transmitting 
information on the heat engine speed, and the unit comparing the measured 
rotational speed with the preset value set up main feedback of the 
governors. A fault in the electric circuits in the main feedback line, 
e.g. due to oxidation of the contacts in plug-and-socket connectors or a 
break of the wire, result in that the control signal applied to the 
electric motor and not compensated by the feedback reaches its maximum 
value, so that the fuel dosing device is set to the maximum feed position, 
and the heat engine operates in a racing mode. To reduce a probability of 
heat engine racing, the feedback components are doubled, while the engine 
energency stop controller is added with various limit and emergency 
switches for disconnecting the electric controls of the motor. In order to 
deenergize the control circuit for eliminating the racing mode of the heat 
engine, the fuel dosing device must be moved towards the fuel cutoff 
point. This is done by providing the governor with a special spring which 
creates an additional load on the electric motor and this requires an 
increase of the input power of this motor still further. 
Known in the art is a heat engine speed governor based on a high-speed 
electric drive (USSR Inventor's Certificate No. 708065 published in 
bulletin "Otkrytiya, izobreteniya, promyshlennye obraztsy, tovarnye znaki" 
No. 1, 1980) comprising an electric motor with unilateral direction of 
rotation kinematically connected to the input shaft of a differential 
mechanism whose other shaft is rotated by a heat engine while the output 
shaft thereof is kinematically connected to a fuel dosing device of the 
heat engine, a channel for controlling the rotational speed of the 
electric motor, in which the speed meter is electrically connected to the 
input of control signal forming unit whose setting input is connected to 
the output of a unit for forming a program of controlling the electric 
motor speed having a task setting input, an output electriclly connected 
to the electric motor and a channel for correction of the motor speed 
under transient operating conditions in response to the heat engine speed 
connected to the correction input of the unit forming the control signal 
in the motor speed control channel. 
In the described speed governor the input shafts of the differential 
mechanism are rotated by the heat engine and by the electric motor in 
opposite directions. When the speed of both shafts is the same, the output 
shaft of the differential mechanism and the associated fuel dosing device 
are stationary. When the load on the heat engine or the preset speed of 
one of the input shafts is changed, the output shaft rotates and moves the 
fuel dosing device to a postion corresponding to the new load or speed 
conditions of the heat engine, under which the rotational speeds of the 
input shaft are the same. The presence of a differential mechanism in the 
speed governor being discussed makes it possible to use a conventional 
electric motor of unilateral direction of rotation. In this governor the 
mechanical transmission from the heat engine shaft to the input shaft of 
the differential mechanism plays a role of main feedback. 
To increase the accuracy of maintaining the rotational speed of the heat 
engine provided in this governor due to stabilization of the electric 
motor speed, the speed meter is connected directly to the input of the 
control signal forming unit. To improve the quality of control of the heat 
engine speed under transient conditions, i.e. duration of the control 
process and the value of deviation of the heat engine speed from a 
predetermined value, the speed meter of the electric motor speed 
correction channel is coupled to the electric motor and electrically 
connected to the correction input of the control signal forming unit 
through the differential mechanism. The unit forming the program for 
controlling the electric motor speed is a power supply unit, in which the 
output voltage can be varied thus changing the speed of the electric motor 
and, therefore, the speed of the heat engine. The control signal forming 
unit is made as an amplifier. 
In the speed governor under discussion the signal from the heat engine 
speed meter is converted in the differentiating unit; therefore, under 
steady-state conditions the information on the heat engine speed is not 
transmitted to the control signal forming unit, while the accuracy of 
maintaining the heat engine speed depends entirely on the accuracy of 
maintaining the speed of the electric motor. Such a scheme of the 
governor, in which the speed of the heat engine is controlled not by 
deviation of the parameter being controlled but by a parameter indirectly 
connected with the former, does not provide the required accuracy of 
maintaining the heat engine speed. 
SUMMARY OF THE INVENTION 
The basic object of the invention is to provide a speed governor for heat 
engine having such a channel for controlling the electric motor speed, 
which would make it possible to effect the control directly by the speed 
of the heat engine, thus improving the accuracy of maintaining its 
rotational speed. 
This object is attained by providing a heat engine speed governor 
comprising an electric motor with unilateral direction of rotation 
kinematically cconnected to the input shaft of a differential mechanism 
whose other shaft is rotated by a heat engine while the output shaft 
thereof is kinematically connected to a fuel dosing device of the heat 
engine. A channel for controlling the rotational speed of the electric 
motor includes a speed meter electrically connected to the input of the 
control signal forming unit, whose setting input is connected to the 
output of a unit for forming a program of control of the electric motor 
speed having a task setting input and whose output is electriclly 
connected to the electric motor. A channel correcting the motor speed 
under transient operating conditions in response to the heat engine speed 
is connected to the correction input of the unit forming the signal to 
control the motor speed. According to the invention, the speed meter is 
connected to the heat engine. The electric motor speed control channel is 
provided with a comparison unit, one input of which is connected to the 
speed meter while the other input is connected to the unit forming a 
program for controlling the electric motor speed; and an integrator whose 
input is connected to the output of the comparison unit while the output 
is connected to the input of the control signal forming unit. 
The fact that the electric motor speed control channel includes a heat 
engine speed meter, a comparison unit and an integrator used for signal 
conversion makes it possible to keep the control signal at a level 
proportional to the integral of deviation of the heat engine speed from a 
required value. The integrated error signal reduces the heat engine speed 
deviation from the preset value so that the engine speed is maintained at 
high accuracy within a specified tolerance.

DETAILED DESCRIPTION OF THE INVENTION 
The heat engine speed governor 1 comprises an electric motor 2 
characterized by unidirectional rotation kinematically connected to the 
input shaft 3 of a differential mechanism 4. The other input shaft 5 of 
the differential mechanism 4 is rotated by a heat engine 6, which in the 
embodiment described is kinematically connected to its shaft 7. The output 
shaft 8 of the differential mechanism 4 is kinematically connected to a 
fuel dosing device 9 of the heat engine 6. The kinematic couplings of the 
differential mechanism 4 are shown in the drawing in the form of a gear 
transmission. 
The speed governor 1 also comprises an electric motor speed control channel 
10. Mounted at the input of the speed control channel 10 is a heat engine 
speed meter 11, which in this embodiment consists of a position transducer 
12 coupled to the input shaft 5 of the differential mechanism 4 and 
connected to the input of a converter 13 converting the position of the 
input shaft into an electric signal. The converter 13 is connected to an 
input 14 of a comparison unit 15 comparing the heat engine speed with a 
required speed of the second electric motor. Connected to the input 16 of 
the comparison unit 15 is the output of a program forming unit 17 forming 
a program for controlling the speed of the electric motor, said unit 17 
being provided with a program input 18. The output of the program forming 
unit 17 is also connected to the setting input 19 of a control signal 
forming unit 20. 
The output of the comparison unit 15 is connected to the input of an 
integrator 21 whose, output is connected to the input 22 of the control 
signal forming unit 20. 
Provided at the input 22 of the control siganl forming unit 20 is a 
threshold element 23 having an input 24 for setting a task determined by 
the limits of deviation of the rotational speed of the heat engine 6 from 
a preset value. The output of the threshold element 23 is connected to the 
input of an electric signal converter 25 whose output is connected to the 
input 26 of an adder 27 whose other input is the setting input 19 of the 
control signal forming unit 20. The output of the adder 27 is connected to 
the input 28 of an adder 29 whose other input is a correction input 30 of 
the control signal forming unit 20. 
The output of the adder 29 is connected to the input of a control signal 
converter 31 whose, output is connected to the input of a threshold 
element 32 protecting the electric motor 2 against overloads. The 
threshold element has an input 33 for setting a task determined by a 
permissible load of the electric motor 2. The output of the threshold 
element 32 is an output of the control signal forming unit 20 and is 
connected to the electric motor 2. 
The speed governor 1 also comprises a correction channel 34 for correction 
of the electric motor speed under transient conditions in response to the 
speed of the heat engine, at the input of which there is installed a speed 
meter 11, which is common for the channel 34 and for the speed control 
channel 10. The output of the heat engine speed meter 11 is connected to 
the input of a differentiating unit 35 whose output is connected to the 
input of an electric signal converter 36. The output of the converter 36 
is an output of the correction channel 34 and is connected to the 
correction input 30 of the control signal forming unit 20. 
The heat engine speed governor 1 operates as follows. The input shaft 3 of 
the differential mechanism 4 is rotated by the electric motor 2 at a 
predetermined speed, while the input shaft 5 is rotated by the shaft 7 of 
the heat engine 6 in the opposite direction. If the speed of the input 
shaft 3 is equal to that of the input shaft 5, the output shaft 8 of the 
differential mecahanism 4 and the associated fuel dosing device 9 are at 
rest. When the load on the heat engine increases the rotational speed of 
the shaft 5 decreases and the difference between the speeds of the shafts 
3 and 5 results in rotation of the shaft 8, which moves the fuel dosing 
device 9 for increasing the fuel supply. This increases the speed of the 
shaft 7 of the heat engine 6 and shaft 5 to a value at which the speed of 
the shaft 3 becomes equal to that of the shaft 5 and the output shaft 8 
with the fuel dosing device 9 stop moving. After that the transient 
process of speed regulation is over and the heat engine 6 continues to 
operate under steady-state conditions corresponding to the preset speed of 
the electric motor 2. The speed of the heat engine 6 with a decreasing 
load is controlled in a similar manner. In this case the fuel dosing 
device 9 moves in the direction of reducing the fuel supply. When the 
electric motor 2 rotates at a speed below the preset value, the equality 
of speeds of the shafts 3 and 5 is broken so that the shaft 8 and the fuel 
dosing device 9 move in the direction of reducing the fuel supply until 
the speed of the shaft 5 connected to the heat engine becomes equal to the 
newly set speed of the shaft 3 driven by the electric motor 2. The speed 
of the heat engine 6 in the case of increasing the speed of the electric 
motor 2 is controlled in a similar way. In this case the fuel dosing 
device 9 moves for increasing the fuel supply. 
Since the shaft 3 and 5 of the differential mechanism 4 are kinematically 
connected to the electic motor 2 and the heat engine 6 respectively, their 
speeds have a ratio equal to the transmission ratio of the gearing between 
the heat engine 6, electric motor 2 and differential mechanism 4. Thus, 
under steady-state conditions the rotational speed of the heat engine 6 is 
proportional to the speed of the electric motor 2, while the control of 
the speed of the heat engine 6 is effected by using the control functions 
of the electric motor 2. 
The electric motor 2 is controlled via the speed control channel 10 in 
accordance with a program set via the input 18. The input 18 is generally 
a conbination of inputs through which there are applied signals carrying 
data on the parameters of the heat engine and the machine unit in which 
this engine is mounted. Depending on the combination of the data signals 
fed into the control program forming unit 17 through the input 18, the 
program for optimum control of the electric motor 2 is formed. In 
particular, to the input 18 of the unit 17 there may be applied signals 
characterizing the speed and load of the heat engine 6, the temperature of 
the cooling liquid, oil, exhaust gases, supercharging pressure, 
atmospheric pressure, accelerator pedal position, transmission parameters, 
vehicle speed, distribution of the load between the units operating in 
parallel, and other parameters. The task signal is fed into the program 
forming unit 17, which produces signals applied to the setting input 19 of 
the control signal forming unit 20. 
The rotational speed of the heat engine 6 is measured by the meter 11 
installed at a place convenient for its mounting and for taking off the 
signal. In the embodiment described in this specification the meter 11 is 
mounted within the zone of the input shaft 5 of the differential mechanism 
4. 
The output signal of the meter 11 is applied to the input 14 of the 
comparison unit 15. The other input 16 of the comparison unit 15 is fed 
with a signal formed in the signal forming unit 17. The error signal 
proportional to the difference between the real speed and the preset speed 
of the heat engine 6 from the output of the comparison unit 15 is applied 
to the input of the integrator 21 storing the measurement error. 
The output signal of the integrator 21 is applied to the input 22 of the 
control signal forming unit 20 and then to the threshold element 23, which 
operates when the signal reaches a predetermined level. The threshold 
element 23 is adjusted for permissible deviation of the speed of the heat 
engine 6 from a preset value using the input 24. As soon as the deviation 
overcomes the permissible value, the integrated signal is fed to the 
converter 25 in which it is converted in response to the signal fed to the 
input 19 of the control signal forming unit 20. The signal summed up in 
the adder 27 is fed through the adder 29, summing up the control and 
correction signals, to the converter 31, from the output of which the 
signal, e.g. in the form of timing pulses, is fed to the control windings 
of the electric motor 2. 
The channel 10, heat engine speed meter 11, comparison unit 15 and 
integrator 21 in combination with the threshold element 23 provided in the 
speed governor 1 increase the accuracay and stability of the rotational 
speed of the heat engine 6 under steady-state conditions. 
The output signal of the converter 31 is fed through the threshold element 
32 to the output of the control signal forming unit 20, from which it is 
fed to the windings of the electric motor 2. The electric motor 2 can be 
overloaded in the case of higher friction in the differential mechanism 4, 
in the electric motor 2 itself and in its fuel dosing device 9. The raised 
friction not only overloads the electric motor 2 by overheating its 
windings but in the case of wedging the fuel dosing device 9 can result in 
racing of the heat engine 6. Therefore, during overloads the threshold 
element 32 switches off the electric motor 2, which runs to rest thus 
automatically stopping the heat engine 6. The electric motor 2 is adjusted 
for a limiting overload by the input 33. The threshold element 32 
increases the reliability of the speed governor 1 and that of the heat 
engine 6 being controlled. 
The operation of the speed governor 1 is basaed on astatic (high-speed) 
principle of control and this makes it possible to accurately maintain the 
speed of the heat engine 6 under steady-state operating conditions. On the 
other hand, the astatic control system have a tendency to 
self-oscillation. This disadvantage can be eliminated by improving the 
quality of controlling the speed of the heat engine 6 under transient 
conditions. This is effected by providing dynamic correction, i.e. by 
introducing a derivative of the controlled value (speed of the heat engine 
6) into the channel 34 correcting the electric motor speed. 
The output signal of the heat engine speed meter 11 is fed to the input of 
the differentiating unit 35. From the unit 35 the correction signal is fed 
to the converter 36, where it is converted to a type corresponding to the 
signal at the output of the adder 27. From the output of the converter 36 
the converted signal is applied to the correction input 30 of the control 
signal forming unit 20 and then is fed to the adder 29 which sums up the 
control and correction signals fed from the adder 27 and the converter 36. 
The power supply of the electric motor 2 and the components of the channels 
10 and 34 are effected in an ordinaray way by connecting them to the power 
supply system of the heat engine 6 or to a self-contained power pack. 
Thus the claimed governor can operate both under steady-state and transient 
condition,, features high reliability, low power consumption, simple 
design and a low cost of the electromechanical part, while providing high 
accuracy of maintaining a predetermined speed of a heat engine preset 
within a wide range, and high quality of speed control under transient 
operating conditions. Depending on the imposed requirements, the governor 
can be adjusted for permissible instability of the heat engine speed 
manually or automatically. As a result, the governor turns to be a 
universal device capable of operating practically in all machines equipped 
with heat engines. 
INDUSTRIAL APPLICATION OF THE INVENTION 
The invention can be use in internal combustion engines, turbines and other 
types of heat engines, preferably in diesel engines of agricultural 
machinery, diesel automobiles, diesel-electric and turbo-electric units, 
stationary units, industrial, tractor, road and transport machines and 
other machine units with heat engines.