JPS636430Y2 - - Google Patents

Description

[Detailed description of the invention] Industrial application field The present invention is an internal combustion engine that performs control to maintain the actual rotational speed of the internal combustion engine at a set value and control to prevent the actual rotational speed from exceeding the maximum allowable rotational speed. This invention relates to a speed control device.

Prior Art A conventional speed control device of this type is shown in FIG. In the figure, 1 is the controlled internal combustion engine, and 2 is the actual rotational speed N (rpm) of the internal combustion engine 1.
3' is a speed setting signal generation circuit 3a' that generates a speed setting signal Vs that determines the set rotational speed Ns of the internal combustion engine, and a maximum allowable rotational speed Nm of the internal combustion engine. A speed setting section 4 includes a maximum speed setting signal generation circuit 3b' that outputs a maximum speed setting signal Vm that determines the maximum speed setting signal Vm, and a speed setting section 4 receives the speed setting signal Vs and the speed detection signal Vn as inputs and converts the actual rotational speed N to the set rotational speed Ns. A calculation unit 5 outputs the control signal Vc necessary for matching, and decelerates the internal combustion engine when the rotational speed N reaches the maximum allowable rotational speed Nm by inputting the maximum speed setting signal Vm and the speed detection signal Vn. This is an overspeed detection section that outputs a deceleration command signal Vd that instructs this. Reference numeral 6 denotes an operating section consisting of a drive circuit 6a which receives a control signal Vc and a deceleration command signal Vd, and an operating section 6b which is driven by the drive circuit and operates a speed adjusting section 7 that adjusts the rotational speed of the internal combustion engine. , this operating section has a speed adjusting means (for example, adjusting the injection amount of a throttle valve or a fuel injection pump) that adjusts the speed of the internal combustion engine so that the actual rotational speed N matches the set rotational speed Ns in accordance with the control signal Vc. 7, and when the deceleration signal Vd is input, the speed adjusting means 7 is operated so as to reduce the actual rotational speed of the internal combustion engine.

According to the above device, it is possible to control the engine rotation speed to maintain it at a set value, and if the control system is unable to follow sudden changes in load and the rotation speed suddenly increases, the engine rotation speed can be prevented from exceeding the maximum allowable rotation speed.

By the way, in general, the set rotational speed of an internal combustion engine is changed depending on the type of load, but when the load is changed, the maximum allowable rotational speed must be changed for the purpose of preventing damage to the load. is often necessary. Therefore, when the set rotational speed is changed in accordance with the load, it is desirable to be able to change the maximum allowable rotational speed in accordance with the change in the set rotational speed. However, in the conventional device described above, the speed setting signal generation circuit 3a' and the maximum speed setting signal generation circuit 3b' are provided separately, and the maximum allowable rotation speed is a constant value determined by the performance of the engine regardless of the set rotation speed. Therefore, once the engine was determined, the maximum allowable rotation speed remained constant no matter how the set rotation speed was set, making it impossible to set the maximum allowable rotation speed according to the demands of the load side. In the above device, it may be possible to adjust the maximum speed setting signal and the speed setting signal individually, but in this case, the maximum speed setting signal is changed each time the set rotation speed is changed. Therefore, the adjustment work becomes extremely troublesome.

OBJECT OF THE INVENTION An object of the present invention is to provide an internal combustion engine speed control device that can automatically determine the maximum allowable rotation speed in a certain relationship with the set rotation speed.

Structure of the invention The present invention includes a speed detection section that detects the actual rotational speed of an internal combustion engine and outputs a speed detection signal, a speed setting signal that determines a set rotational speed of the internal combustion engine, and a maximum allowable rotational speed of the internal combustion engine. a speed setting section that outputs a maximum speed setting signal to be determined; and a calculation section that receives the speed setting signal and the speed detection signal as input and outputs a control signal necessary to make the actual rotation speed match the set rotation speed. , an overspeed detection section that receives the maximum speed setting signal and the speed detection signal as input and outputs a deceleration command signal instructing to decelerate the internal combustion engine when the rotation speed exceeds the maximum allowable rotation speed; , operating a speed adjusting means for adjusting the speed of the internal combustion engine in accordance with the control signal so that the actual rotational speed matches the set rotational speed, and when the deceleration signal is input, the actual rotational speed of the internal combustion engine is adjusted. An internal combustion engine speed control device comprising an operating section for operating the speed adjusting means to decrease the speed, wherein in the present invention, the speed setting section is formed by connecting a first and a second resistor in series. It includes a resistor series circuit and a power supply circuit that allows a substantially constant current to flow through the resistor series circuit. and at least the second resistor of the first and second resistors.
The resistor is configured to be able to adjust its resistance value, and the maximum speed setting signal is obtained at both ends of the resistor series circuit, and the speed setting signal is obtained at both ends of the second resistor. .

With the above configuration, when the set rotational speed is changed, the maximum allowable rotational speed can be automatically set in a certain relationship with the set rotational speed, so the maximum allowable rotational speed can be set automatically according to the load requirements. The rotation speed can be easily set.

Embodiments Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.

Fig. 2 shows an embodiment of the present invention, in which numeral 1 indicates an internal combustion engine to be controlled, numeral 2 indicates an actual rotational speed N of the internal combustion engine 1, and Fig. 4 shows the actual rotational speed N of the internal combustion engine 1. 3 is a speed detection unit that outputs a speed detection signal Vn that changes as shown in FIG.
4 is the speed setting signal Vs.
and the speed detection signal Vn as input, the actual rotational speed N is calculated.
5 is a calculation unit that outputs the control signal Vc necessary to match the set rotational speed Ns, and 5 is a calculation unit that receives the maximum speed setting signal Vm and the speed detection signal Vn as input, and when the rotational speed N reaches the maximum allowable rotational speed Nm. Deceleration command signal Vd commands to decelerate the internal combustion engine to
For example, this overspeed detection section compares signals Vm and Vn and determines that Vn>Vm.
It consists of a comparator that outputs a deceleration command signal when . 6 is the control signal Vc and deceleration command signal
The operating section is composed of a drive circuit 6a that receives Vd as an input, and an operating section 6b that is driven by the drive circuit to operate the speed adjusting section 7 that adjusts the rotational speed of the internal combustion engine. Accordingly, the speed adjusting means 7 is operated so that the actual rotational speed N matches the set rotational speed Ns, and when the deceleration signal Vd is input, the speed adjusting means 7 is operated so as to reduce the actual rotational speed of the internal combustion engine. do.

In the case of a gasoline engine, the speed adjusting means 7 is, for example, a throttle valve, and in the case of a diesel engine, it is, for example, a rack for adjusting the injection amount of a fuel injection pump. The operating means 6b is, for example, an actuator that drives an arm or lever connected to the throttle valve or rack using a drive source such as an electric motor or an electromagnetic plunger. The drive circuit 6a drives the operating means so that the actual rotational speed of the engine matches the set value in response to the control signal Vc, and drives the operating means to reduce the rotational speed of the engine in response to the deceleration command signal Vd. The circuit is configured as appropriate depending on the configuration of the operating means.

In the above embodiment of the present invention, the difference from the device shown in FIG. 1 is the configuration of the deceleration setting section 3. The speed setting section 3 of the present invention includes a resistor series circuit 3A formed by connecting a first resistor 31 and a second resistor 32 in series.
and a power supply circuit 3B that causes a substantially constant current i to flow through the resistor series circuit 3A. Here, at least the second resistor of the first resistor 31 and the second resistor 32
The resistor 32 consists of a variable resistor, and the maximum speed setting signal Vm is connected to both ends of the resistor series circuit 3A.
A speed setting signal Vs is obtained at both ends of the resistor 32. The power supply circuit 3B can be configured by, for example, a constant current circuit using constant current characteristics of a field effect transistor and a power supply.

In the above embodiment, if the resistance value of the first resistor 31 and the resistance value of the second resistor 32 are R1 and R2, respectively, Vs=iR2, Vm=i(R1+R
2)=iR1+Vs. Here, since iR2 is constant, change the resistance value R2 to set the rotation speed Ns.
When changing the speed setting signal Vs and the maximum speed setting signal Vm, the speed setting signal Vs and the maximum speed setting signal Vm change with a constant relationship as shown in FIG. Therefore, according to the above-mentioned device, when the set rotational speed is changed according to the load, the maximum speed setting signal Vm can be automatically changed in a certain relationship with the speed setting signal Vs.

In the above embodiment, a fixed resistor is used as the first resistor 31, but both the first resistor 31 and the second resistor 32 are variable resistors, so that the set rotation speed and the maximum allowable rotation speed can be adjusted. It is also possible to adjust the relationship between them. Note that the first
It goes without saying that the second resistor and the second resistor do not necessarily need to be constructed from a single resistor, and each of these resistors may be constructed from a plurality of resistors connected in series or in parallel.

FIG. 3 shows the main part of another embodiment of the present invention, in which the overspeed detection section 5 consists of a voltage comparator CR. Further, in this embodiment, a collector-emitter circuit of a PNP transistor 33 is connected to both ends of the first resistor 31 of the speed setting section 3.
The transistors are connected in parallel so as to be biased in the forward direction by a voltage across both ends of the transistor, and the base of the transistor is connected to the output terminal of the voltage comparator CP constituting the overspeed detection section 5. In other respects, the structure is similar to that of the embodiment shown in FIG.

In the embodiment shown in FIG. 3, when the actual rotational speed of the engine is below the maximum allowable rotational speed and the speed detection signal Vn is below the maximum speed setting signal Vm (Vn≦Vm), the potential of the output terminal of the overspeed detection section 5 is high. It's on the level. At this time, since no base current flows through the transistor 33, the transistor is in a cut-off state.
The transistor 33 has no effect on the signals Vs and Vn. At this time, the speed setting signal is
Vs and maximum speed setting signal Vm are set. When the actual rotational speed of the engine exceeds the maximum allowable rotational speed due to a sudden change in load, etc., and the signal Vn becomes larger than Vm (Vn>Vm), the potential at the output terminal of the overspeed detection section 5 becomes a low level, and the drive circuit A deceleration command is given to transistor 6a, but at this time transistor 3
Since the base current flows through the transistor 3 and makes the transistor conductive, the first resistor 31 becomes substantially short-circuited, and the maximum speed setting signal Vm becomes approximately equal to the speed setting signal Vs. When the actual rotational speed of the engine is reduced by the deceleration command and Vn≦Vm=Vs, the output of the overspeed detection section 5 becomes high level again, the transistor 33 is cut off, and the normal state is restored.

In the embodiment shown in FIG. 2, no deceleration command is given as soon as the actual rotational speed falls below the maximum allowable rotational speed, so speed control is performed only by the output of the arithmetic circuit 4. In some cases, the actual rotational speed may exceed the maximum allowable rotational speed again due to a delay in the response of the control system, causing a hunting phenomenon. In contrast, in the embodiment shown in FIG. 3, once the actual rotation speed exceeds the maximum allowable rotation speed, the over-speed detection section issues a deceleration command to the drive circuit until the actual rotation speed returns to the set rotation speed. Therefore, the rotation speed can be quickly returned to the set rotation speed, and the hunting phenomenon can be prevented from occurring.

In each of the above embodiments, the speed is adjusted by adjusting the supply of fuel to the engine, but the speed may also be adjusted by controlling the ignition position of the internal combustion engine. In this case, the circuit that controls the ignition position of the ignition device for the internal combustion engine serves as the speed adjustment means, and the operating section sends a signal to advance or retard the ignition position in accordance with the output of the calculation section. The ignition position control circuit is configured to provide a signal commanding the ignition position control circuit.

Effects of the invention As described above, according to the invention, when the set rotation speed is changed, the maximum allowable rotation speed can be automatically set in a certain relationship with the set rotation speed, so that the maximum allowable rotation speed can be automatically set according to the load demand. This has the advantage that the maximum allowable rotation speed commensurate with the speed can be easily set.

[Brief explanation of the drawing]

Fig. 1 is a block diagram showing a conventional example, Fig. 2 is a block diagram showing an embodiment of the present invention, Fig. 3 is a circuit diagram showing main parts of another embodiment of the present invention, and Fig. 4 is a diagram showing the relationship between rotational speed and speed detection signal,
FIG. 5 is a diagram showing the relationship between the set rotational speed, the speed setting signal, and the maximum speed setting signal. DESCRIPTION OF SYMBOLS 1... Internal combustion engine, 2... Speed detection section, 3... Speed setting section, 4... Calculation section, 5... Overspeed detection section,
6...Operation unit, 7...Speed adjustment means.

Claims (1)

[Scope of utility model registration request] a speed detection unit that detects an actual rotational speed of the internal combustion engine and outputs a speed detection signal; a speed setting signal that determines a set rotational speed of the internal combustion engine; and a maximum speed setting signal that determines a maximum allowable rotational speed of the internal combustion engine. a speed setting section that outputs the speed setting signal; a calculation section that receives the speed setting signal and the speed detection signal as input and outputs a control signal necessary to make the actual rotation speed match the set rotation speed; and the maximum speed setting signal. an overspeed detection unit that receives the speed detection signal as input and outputs a deceleration command signal that instructs to decelerate the internal combustion engine when the rotational speed exceeds the maximum allowable rotational speed, and sets the actual rotational speed. A speed adjusting means for adjusting the speed of the internal combustion engine to match the rotational speed is operated in accordance with the control signal, and when the deceleration signal is input, the speed is adjusted so as to reduce the actual rotational speed of the internal combustion engine. In the internal combustion engine speed control device, the speed setting section includes a resistor series circuit formed by connecting a first and a second resistor in series, and a substantially constant current flowing through the resistor series circuit. a power supply circuit that allows a current to flow, at least the second resistor of the first and second resistors is configured to be able to adjust its resistance value, and the maximum speed setting signal is applied to both ends of the resistor series circuit. , and an internal combustion engine speed control device, wherein the speed setting signal is obtained at both ends of the second resistor.