JPH0240857B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an electronically controlled governor for an engine, and particularly to an electronically controlled governor for an engine that can quickly respond to instantaneous load fluctuations.

[Conventional technology]

For example, in an engine that drives a generator, it is necessary to severely suppress the rate of governor fluctuation in order to obtain a stable voltage. Conventionally, such engines have generally employed a mechanical governor to control the rotational speed to a constant level in response to load fluctuations.

Note that there is Japanese Patent Publication No. 47-30069 regarding the control of speed governors, which also describes a mechanism for manually operating the setting adjustment member of a mechanical governor using a lever, an electric control circuit, and an electric servo motor. An apparatus equipped with an electric governor control system including a control system is disclosed in Japanese Patent Application Laid-Open No. 54-67124. Furthermore, Japanese Patent Application Laid-Open No. 48-45788 discloses an electronically controlled rotational speed governor that controls fluctuations in engine speed when the engine is under load and the load fluctuates.

[Problem to be solved by the invention]

However, the mechanical governor alone, such as the first prior art described above, cannot sufficiently follow instantaneous fluctuations in load, and as shown in Figure 1a, the instantaneous fluctuation rate of the governor is large and the set value does not reach the set value. The drawback is that it takes a long time to converge.

In addition, in the second prior art, the rotation speed control is performed only by a mechanical governor in manual operation, and the mechanical governor is electrically controlled in automatic operation, making the configuration complicated. Additionally, there is a problem in that the driver is required to select one of the control methods depending on the driving operation, making the operation cumbersome. Furthermore, when automatic operation is selected and electrical governor control is used, the set rotation speed must be selected using a selector switch, and even when the rotation speed fluctuation range is small, the control is always performed by a DC servo motor, etc. Because of this, there is a problem that the battery load is large.

Furthermore, in the third prior art, fluctuations in the engine speed when the engine load fluctuates in a certain load state are controlled by an electronically controlled rotation speed governor, and the engine speed changes from no load to a load state. There is a problem in that it is not possible to control overshoot of the engine speed when the load changes from a loaded state to a no-load state.

The present invention has been made in view of the above points, and is capable of quickly responding to instantaneous load fluctuations when an engine is switched from a loaded state to a no-load state, or when the engine is switched from a no-load state to a loaded state. It is an object of the present invention to provide an electronically controlled governor for an engine capable of realizing a small instantaneous fluctuation rate and a short convergence time.

[Means for Solving the Problems] In order to achieve the above object, the present invention provides a system in which one end of a governor lever operated by a mechanical governor is connected to a throttle lever that opens and closes a throttle valve of a carburetor via a connecting rod. In the engine that uses both the mechanical governor and the electronically controlled governor, the electronically controlled governor is connected to the other end of the governor lever, and first and second drives drive the throttle valve in the opening direction and the closing direction. a rotation speed detection circuit connected to the primary side of the ignition system of the engine to detect the rotation speed of the engine; and a lower limit rotation speed set lower than the load setting rotation speed by the mechanical governor when the engine is loaded. and an engine rotational speed based on an output signal from the rotational speed detection circuit, and if the engine rotational speed reaches a lower limit set rotational speed or less, outputs a signal to drive the first drive device for a certain period of time. At the same time, when it is detected that the engine rotation speed has returned to the load setting rotation speed or more, a first drive signal that stops outputting the drive signal to the first drive device even before the predetermined period of time has elapsed. The control circuit compares the engine rotation speed with the upper limit setting rotation speed set higher than the no-load settling rotation speed by the mechanical governor during no-load of the engine, and determines that the engine rotation speed is equal to or higher than the upper limit rotation speed. If reached,
When outputting a signal to drive the second drive device for a certain period of time and detecting that the engine speed has returned to the no-load setting speed, the second drive device may be driven even before the certain period of time has elapsed. and a second control circuit that stops outputting the drive signal to the second drive device, and when the first and second control circuits stop the first and second drive devices, fluctuations in the rotation speed are controlled. is configured to be controlled by the mechanical governor.

〔Example〕

Next, one embodiment of the present invention will be described based on the drawings.

In FIG. 2, reference numeral 1 denotes the engine body, and a governor lever 3 is installed on the side of the carburetor 2 located above so as to swing around a bent part, and a connecting rod 4 is attached to the upper end of the governor lever 3. The throttle lever 5 of the carburetor 2 swings clockwise around the fulcrum of the governor lever 3 in the figure and pushes the connecting rod 4 to close the throttle valve (not shown), and conversely, the throttle lever 5 of the carburetor 2 is moved counterclockwise. The throttle valve is connected so that the throttle valve can be opened by swinging the connecting rod 4 and pulling the connecting rod 4.

A governor shaft of a centrifugal bell-type mechanical governor (not shown) is fixed to the fulcrum of the governor lever 3, and the mechanical governor drives the governor lever 3 to open and close the throttle valve to keep the engine speed N constant. Control the rotation speed.

The control of the engine speed N using only this mechanical governor is as shown in FIG.
When the load setting rotation speed Ns ₂ suddenly switches to no-load, the engine rotation speed N (Ns ₂ ) exceeds the no-load setting rotation speed Ns ₁ and reaches a large peak value N ₃ , and the no-load settling rotation speed When a load is suddenly applied from a few Ns ₁ , the engine speed N (Ns ₁ ) decreases beyond the load settling speed Ns ₂ , and a similarly large peak value N ₄
It reaches to. Therefore, it is not possible to reduce the instantaneous fluctuation rate and quickly converge to a stable rotational speed using a mechanical governor alone.

Therefore, in the present invention, the governor lever 3
is controlled by an electronically controlled governor in addition to a mechanical governor, and the throttle valve is opened and closed in response to instantaneous fluctuations in engine speed when switching between no-load and loaded states.

6 and 7 are the first in this electronically controlled governor,
When the first drive device 6, which is a second drive device and is located on both sides of the lower end of the governor lever 3 and is connected to the governor lever 3, and is located on the right side in the figure, is driven, the governor lever 3 swings counterclockwise. When the throttle valve of the carburetor 2 is opened and the second drive device 7 located on the left side is driven, the governor lever 3 is swung clockwise and the throttle valve is closed. The pair of drive devices 6 and 7 can be constructed using, for example, solenoids, and the locations shown in this embodiment are not critical as long as the locations are such that the throttle valve can be opened and closed.

FIG. 3 shows the first and second drive devices 6, 7 in an engine employing a point-type ignition system.
FIG. 2 is a block diagram of an electric circuit that controls a spark plug, which will be described later. In the figure, 11 is a battery, the output of which is input to the primary side of the ignition system 13 via a key switch 12 that is turned on and off by the engine key, and is also input to the control device 15 via a resistor 14. ing. This control device 15 controls the ignition system 1 at a predetermined timing.
A pulse is input to the primary side of 3, and the spark plug 16 connected to the secondary side is ignited. Further, inside this control device 15, a control circuit for the electronically controlled governor of the engine described above is provided.
The operation of the second drive devices 6 and 7 is controlled.

The control circuit of this electronically controlled governor will be explained based on FIG. In the figure, 21 is a rotational speed detection circuit that detects the engine rotational speed N from the primary side of the ignition system 13, and its detection output is transmitted to the first and second drive devices 6 and 7, which control the first and second drive devices 6 and 7, respectively. The signal is input to the control circuits 22 and 23 of. Here, the second
The control circuit 23 is set with an upper limit rotation speed N _H that is slightly higher than the no-load settling rotation speed Ns ₁ based on the no-load settling rotation speed Ns ₁ by the mechanical governor, and the rotation speed detection circuit 21 is When a rotation speed N higher than the upper limit rotation speed N _H is detected, the second drive device 7 is immediately operated for a certain period of time T (preferably about 0.2 seconds to 0.8 seconds), and the throttle valve of the carburetor 2 is activated via the governor lever 3. close. and,
At this time, the second control circuit 23 detects that the engine rotation speed N from the rotation speed detection circuit 21 is a rotation speed of N≧N _H , and before a certain period of time T has elapsed, the engine rotation speed N becomes unloaded. When it is detected that the set rotation speed Ns has returned to below ₁ , the operation of the second drive device 7 is automatically stopped even before the above-mentioned predetermined time T has elapsed, and the opening and closing of the throttle valve is thereafter controlled by the mechanical governor. controlled.

Further, the first control circuit 22 is set with a lower limit rotation speed N _L that is slightly lower than the load settling rotation speed Ns ₂ based on the load settling rotation speed _{Ns 2 which} is lower than the no-load settling rotation speed Ns 1. When the rotational speed detection circuit 21 detects an engine rotational speed N that is less than the lower limit set rotational speed N _L , the first drive device 6 is immediately operated for a certain period of time T to open the throttle valve. In addition, the first control circuit 22 detects that the engine speed N from the rotation speed detection circuit 21 is a rotation speed of N≦N _L before a certain period of time T elapses. When it is detected that the set rotational speed Ns has returned to ₂ or more, the operation of the first drive device 6 is automatically stopped even after the above-mentioned predetermined time T has elapsed, and the opening and closing of the throttle valve is thereafter controlled by the mechanical governor. be done.

Note that the first and second control circuits 22 and 23 include the engine rotation speed N detected by the rotation speed detection circuit 21.
is the upper limit set rotation speed N _H or the lower limit set rotation speed N _L
The first and second drive devices 6 and 7 start operating nearby;
In order to avoid racing to a stop, once the drive is activated, it is not activated again for a certain period of time. During this time, the engine speed is stabilized by the mechanical governor.

Next, the action will be explained.

First, the upper limit set rotation speed of the second control circuit 23
As shown in FIG. 1, N _H is set to a value slightly higher than the no-load set rotation speed Ns ₁ by the mechanical governor, and the lower limit set rotation speed N _L of the first control circuit 22 is set as follows.
Set to a lower value than the load settling rotation speed Ns ₂ by the mechanical governor. Let us now consider a case where a predetermined load is applied to the engine, and the engine rotation speed N is controlled to a load-settling rotation speed Ns ₂ by a mechanical governor to control the engine rotation speed in response to load fluctuations.

In this state, when the engine load is abruptly switched to no-load, the engine rotational speed N (Ns ₂ ) rapidly increases toward the no-load settling rotational speed Ns ₁ . However, the mechanical governor has poor quick response to sudden changes in the engine speed N, so if the electronically controlled governor is not operated, the engine speed N will drop to the no-load set speed, as shown in a in Figure 1.
When the peak value N ₃ is reached far exceeding Ns ₁ , a large overshoot occurs, the instantaneous fluctuation rate of the governor increases, and the convergence time to converge to the no-load settling rotation speed Ns ₁ becomes longer.

However, when the electronically controlled governor of the present invention is operated even in response to such rapid load fluctuations, as shown in FIG.
The detected engine speed N in 1 is the no-load settling speed
When the rotation speed exceeds Ns ₁ and reaches the upper limit set rotation speed N _H set in the second control circuit 23, the second control circuit 23 operates the second drive device 7, and the governor lever 3 and the connecting rod 4 , the throttle valve is driven in the closing direction via the throttle lever 5, and the engine speed N is forcibly reduced for a certain period of time T. As a result, the no-load settling rotation speed Ns ₁ of the engine rotation speed N
The amount of overshoot from the engine speed is suppressed to a low level, the instantaneous fluctuation rate of the engine speed N is improved, and the time for convergence to the no-load settling speed Ns ₁ is also shortened. Further, when the engine speed N decreases from the upper limit setting speed N _H to the no-load settling speed Ns ₁ , the driving of the second drive device 7 is stopped even before the above-mentioned fixed time T has elapsed. .

Furthermore, even if a load is suddenly applied to the engine, which is rotating at a no-load settling rotation speed Ns ₁ in a no-load state, for example, the first control circuit 22 operates to drive the first drive device 6. As a result, the engine speed converges to the load settling speed Ns ₂ with a good instantaneous fluctuation rate and a short settling time.

FIG. 5 is a diagrammatic representation of the range of variation when the engine speed N is controlled only by a mechanical governor and the range of variation when it is controlled using an electronically controlled governor. As is clear from the figure, when controlled only by the mechanical governor, the fluctuation range of the engine speed N when switching from no-load state to loaded state or from loaded state to no-load state is N ₃ ~ On the _other hand, when an electronically controlled governor is used for control, the fluctuation range of the engine speed N is N _H to N _L , and the engine speed N is controlled using an electronically controlled governor. By controlling it, the range of fluctuation can be kept small.

FIG. 6 is a circuit diagram showing an example of the rotation speed detection circuit 21 and first control circuit 22 described above.
Here, an ignition pulse signal is input to the rotation speed detection circuit 21 connected to the primary side of the ignition system, and the waveform is shaped.
The NPN transistor Tr ₁ is turned on for a short period of time, and the capacitor 32 of the first control circuit 22 is rapidly discharged. Furthermore, until the next ignition pulse signal is input, the transistor Tr ₁ is turned off, and the capacitor 32 is charged by the circuit power supply V _BAT via the resistor R ₁ , the variable resistor 31, and the resistor R ₂ . Therefore, the capacitor 32 in the eleventh control circuit 22
The peak value of the voltage becomes smaller as the engine speed N increases (the interval between ignition pulse signal inputs becomes shorter), and increases as the engine speed N decreases.

Further, the voltage waveform of the capacitor 32 is input to the inverter IC ₁ , and if the voltage waveform exceeds the threshold level of the inverter IC ₁ , the output signal of the inverter _{IC 1 becomes} L level; The output signal of inverter IC ₁ becomes H level.

The output signal of the above inverter IC ₁ is connected to the base of the PNP transistor Tr ₂ through the resistor R ₃ , so the transistor Tr ₂ is connected to the base of the inverter IC _1.
ON only when the output signal is at L level.

That is, the transistor Tr ₂ has the engine rotation speed N equal to the resistors R ₁ , R ₂ and the variable resistor 31.
The lower limit set rotation speed N _L or less (N≦
Turns ON when N _L ), and turns OFF when N > N _L.

When the transistor Tr ₂ turns on, the capacitor C ₂ is rapidly charged, and the voltage of the capacitor C ₂ is discharged through the resistor R ₄ and gradually decreases.

That is, when the engine speed N is higher than the lower limit set speed N _L , the voltage of the capacitor C ₂ decreases, and when the engine speed N becomes lower than the lower limit set speed N _L , the voltage of the capacitor C ₂ rapidly increases. do.

Since the capacitor C ₂ is connected to the inverter IC ₂ , when the engine speed N is below the lower limit setting speed N _L and the voltage of the capacitor C ₂ is above the threshold level of the inverter IC ₂ ,
The output signal of the inverter IC ₂ changes from H level to L level, and the voltage on the + side of the capacitor 34 goes to 0 level. Once it reaches 0 level, it is gradually charged via resistor R ₅ and variable resistor 33.

As a result, for a certain period of time T from when the capacitor 34 becomes O level until reaching the threshold voltage of the inverter IC ₃ , the inverter
The output signal of IC ₃ becomes H level, and the output signal of inverter IC ₄ becomes L level for a certain period of time T, so NPN transistor Tr ₃ turns OFF.
The NPN transistor Tr ₄ is turned on, the PNP transistor Tr ₅ is turned on, and a drive signal is given to the first drive device 6 .

Therefore, the variable resistor 31 selects the lower limit set rotation speed N L when the engine speed N decreases and the output of the inverter IC ₁ changes from the H level to the L level, and the first control circuit 22 selects the lower limit set rotation speed N _L. 1
By adjusting the resistance value of the variable resistor 33, the fixed time T for driving the drive device 6 of the capacitor 34
By adjusting the charging time constant, when the engine speed N becomes lower than the lower limit set speed N _L ,
During a certain period of time T, a drive signal is applied from the first control circuit 22 to the first drive device 6, and the throttle valve of the carburetor 2 is immediately opened via the governor lever 3 due to the drive of the first drive device 6. The engine rotation speed N is suppressed from falling below the lower limit set rotation speed N _L.

Further, by adjusting the resistance value of the variable resistor 35 in the first control circuit 22, when the engine speed N increases from the lower limit setting speed N _L to the load setting speed Ns ₂ , the certain time T elapses. The driving of the first driving device 6 is stopped even before the above-mentioned operation is performed.

Further, the second control circuit 23 can also be formed in the same manner.

〔Effect of the invention〕

As is clear from the above description, according to the present invention, in an engine that uses both a mechanical governor and an electronically controlled governor, the electronically controlled governor is
first and second drive devices connected to the other end of the governor lever to drive the throttle valve in the opening and closing directions; and a rotation device connected to the primary side of the ignition system of the engine to detect the rotation speed of the engine. The engine speed detection circuit compares the engine speed based on the output signal from the speed detection circuit with the lower limit set speed, which is set lower than the load settling speed by the mechanical governor when the engine is loaded, and determines the engine speed. When the engine speed reaches the lower limit setting speed or less, outputs a signal to drive the first drive device for a certain period of time, and when it is detected that the engine speed has returned to the load setting speed or higher, a first control circuit that stops outputting the drive signal to the first drive device even before the predetermined time period has elapsed; Compare the upper limit set rotation speed and the above engine rotation speed, and if the above engine rotation speed reaches the upper limit set rotation speed or more,
When outputting a signal to drive the second drive device for a certain period of time and detecting that the engine speed has returned to the no-load setting speed, the second drive device may be driven even before the certain period of time has elapsed. and a second control circuit that stops outputting the drive signal to the second drive device, and when the first and second control circuits stop the first and second drive devices, fluctuations in the rotation speed are controlled. Since this is controlled by the mechanical governor, the governor fluctuation rate is reduced and the rotational speed converges to a stable rotation speed quickly.

Furthermore, since the mechanical governor operates even if the electronically controlled governor fails, fluctuations in engine speed can be controlled.

Further, since a mechanical governor and an electronically controlled governor are used together, for example, voltage fluctuations of the generator can be suppressed in any operating state.

[Brief explanation of drawings]

Fig. 1 is a characteristic diagram when the engine speed is controlled by a governor, Fig. 2 is a structural explanatory diagram showing one embodiment of an electronically controlled governor for an engine according to the present invention, and Fig. 3 is an electrical diagram of the engine. Explanatory diagram of the system, 4th
The figure is a block diagram of the electronically controlled governor of the present invention installed in this engine, FIG. It is a circuit diagram. 2...Carburetor, 3...Governor lever, 4
...Connection rod, 5...Throttle lever, 6,7...
...First and second drive devices, 13...Ignition system, 21
...Rotation speed detection circuit, 22, 23...first, second
control circuit.

Claims (1)

[Scope of Claims] 1. An engine that uses both the above mechanical governor and an electronically controlled governor, in which one end of the governor lever operated by the mechanical governor is connected via a connecting rod to a throttle lever that opens and closes the throttle valve of the carburetor. The electronically controlled governor is connected to the other end of the governor lever, and connected to first and second drive devices that drive the throttle valve in the opening direction and the closing direction, and to the primary side of the ignition system of the engine. a rotation speed detection circuit that detects the rotation speed of the engine, and a lower limit setting rotation speed that is set lower than the load settling rotation speed by the mechanical governor when the engine is loaded, and an output signal from the rotation speed detection circuit. Compare the engine speed and if the engine speed reaches the lower limit set speed or less, the first
When it is detected that the engine rotation speed has returned to the load setting rotation speed or higher, the first drive device is outputted even before the elapse of the certain period of time. A first control circuit that stops outputting a drive signal to the engine, compares the engine rotation speed with an upper limit set rotation speed that is set higher than the no-load settling rotation speed by the mechanical governor during no-load of the engine, and When the engine speed reaches the upper limit setting speed or higher, a signal is output to drive the second drive device for a certain period of time, and when it is detected that the engine speed has returned to the no-load setting speed or lower. and a second control circuit that stops outputting the drive signal to the second drive device even before the predetermined period of time has elapsed, and the first and second control circuits An electronically controlled governor for an engine, characterized in that when the second drive device is stopped, fluctuations in the rotational speed are controlled by the mechanical governor.