JPH0115874Y2 - - Google Patents

Description

[Detailed description of the invention] The present invention relates to an electronic governor device for an internal combustion engine for a fire engine, and more specifically, the invention prevents the engine from abnormally revving up when starting, and prevents damage to the pump due to incorrect operation. The present invention relates to an electronic governor device for an internal combustion engine for a fire engine that can prevent the above.

Generally, in a fire engine, one internal combustion engine is used as a driving source for running, and is also used as a driving source for a water pump. Therefore, depending on the mode of use of the engine, the internal connection of the electronic governor that controls the speed of the internal combustion engine, such as a diesel engine, can be switched, and this can be used to control the speed during running or to control the water discharge pressure during water discharge. It is configured so that one can be selectively executed.

FIG. 1 shows a block diagram of a conventional electronic governor circuit of this type. Electronic governor circuit 1
The system controls the position of the fuel adjustment member (not shown) of the fuel injection pump combined with the diesel engine to obtain a running speed according to the accelerator pedal depression state, or to discharge water at a predetermined set water discharge pressure. This is a circuit that controls the rotational speed of a diesel engine. The electronic governor circuit 1 is a control signal generation circuit into which a speed signal N indicating the rotational speed of the engine, a rack position signal R indicating the actual position of the fuel adjustment member, and a detection signal D selected by the changeover switch 2 are input. It has 3.

The changeover switch 2 is a switch whose switching is controlled by the automatic water spray signal W, and in the driving mode, the accelerator position signal A from the accelerator position detection circuit 4 is sent to the control signal generation circuit 3 as a detection signal D via the changeover switch 2. On the other hand, when the automatic water discharge signal W is output and the automatic water discharge mode is entered, the pressure error signal E from the water discharge pressure setting and pressure detection circuit 5 is sent to the control signal generation circuit 3 as the detection signal D via the changeover switch 2. is input. This pressure error signal E is the water discharge pressure set in circuit 5.
This is a signal indicating the difference between Pr and the actual water discharge pressure Pa.

The control signal generation circuit 3 is a circuit that calculates the optimal fuel adjustment member position at any given time based on the above-mentioned input signal, and outputs a control signal _S1 , which is a pulse signal whose duty ratio changes according to the calculation result. be. The control signal S ₁ is input to the drive circuit 7 via the OR circuit 6, where the power is amplified and then applied to the actuator 8 which controls the position of a fuel adjustment member (not shown). The average current flowing through the actuator 8 changes depending on the duty ratio of the control signal S ₁ , and therefore the fuel adjustment member can be positioned at a position according to the result calculated by the control signal generation circuit 3 . As a result, in the drive mode, the engine rotation speed is controlled according to the amount of depression of the accelerator pedal, and in the water discharge mode, the engine rotation speed is controlled so that the actual water discharge pressure is equal to the set water discharge pressure. controlled.

By the way, in this conventional electronic governor circuit 1, the starting signal ST is input to the OR circuit 6, and at the time of starting, the level of the starting signal ST is set to "1", and the fuel adjustment member is controlled by the actuator 8 in the direction of fuel increase. It is designed to be ready for starting the engine when fully tensioned. Therefore, if the water pump is not connected even though the automatic water discharge mode is switched and the automatic water discharge signal W is output, when the start signal ST is output,
Depending on the water discharge pressure setting and the set pressure in the pressure detection circuit 5, the pressure error signal E may become significantly large and control may be performed to cause the engine to overrun. That is, if the water pump is not connected, even if the engine rotational speed increases, an increase in water pressure will not be detected in the circuit 5, and therefore the engine will increase its rotational speed more and more, and eventually the engine rotational speed will decrease. The maximum rotational speed will be reached, causing damage to the equipment.

Therefore, an object of the present invention is to provide an electronic governor device for an internal combustion engine for a fire engine, which reliably prohibits the engine from starting in the automatic water discharge mode and prevents malfunctions when starting the engine. .

Hereinafter, the present invention will be explained in detail with reference to illustrated embodiments.

FIG. 2 shows an embodiment of an electronic governor device for an internal combustion engine for a fire engine according to the present invention. This electronic governor device 11 has the same configuration as the electronic governor circuit 1 explained in FIG. 1 except that a start protection circuit 12 is provided, so in FIG. Corresponding parts are denoted by the same reference numerals and explanations are omitted.

The starting protection circuit 12 prevents the starting signal ST from being input to the OR circuit 6 when the automatic water discharging signal W is output, that is, when the level of the automatic water discharging signal W is "1". The AND circuit 14 is provided with an inverted automatic water spray signal W inverted by 13 being applied to one input and a starting signal ST being applied to the other input. When switched to driving mode, automatic water discharge signal W
The level of is "0", therefore, the switch 2 is switched to take out the accelerator position signal A as the detection signal D, and the level of the inverted automatic water discharge signal W is "1", and the output of the AND circuit 14 is It changes in accordance with the level change of the start signal ST. However, the automatic water spray signal W was switched to water spray mode.
When becomes the "1" level, the output level of the AND circuit 14 is held at "0" regardless of the level state of the start signal ST, and the actuator 8 does not operate in response to the start signal ST.

In addition, in order to forcibly set the level of one fixed contact 2a of the switch 2 to the "1" level in response to the output of the starting signal ST, the starting signal ST is transmitted through the OR circuit 15 so that the cathode is connected to the fixed contact. The voltage is applied to the anode of the diode 16 connected to the diode 2a. The fixed contact 2a is grounded via a resistor 17, and the diode 1
The error signal E is applied to the anode of the diode 18. According to such a configuration, when the starting signal ST is not output (that is, when the level of the starting signal ST is zero)
Since the anode of the diode 16 is approximately at ground potential, the level of the fixed contact 2a can change in accordance with the level change of the error signal E. On the other hand, when the starting signal ST is output and its level becomes approximately equal to the power supply voltage level, the OR circuit formed by the diodes 16, 18 and the resistor 17 causes the error signal E to remain fixed regardless of its level. The level of the contact 2a becomes a high level state approximately equal to the power supply voltage level, and the detection signal D is maintained at a level state similar to that when the actual water discharge pressure is higher than the set pressure. Therefore, even if the automatic water discharge mode is set, for the above-mentioned reason, the control signal generation circuit 3 changes the duty ratio of the signal _S1 in order to position the fuel adjustment member so as to lower the rotational speed of the engine. is determined, and the fuel supply state is such that the engine cannot start.

Furthermore, since the start signal ST is input to the other input of the OR circuit 15 via the delay circuit 19, even after the start switch (not shown) is turned off,
The level of the fixed contact 2a continues to be maintained at a high level until the predetermined time determined by the delay circuit 19 has elapsed. Therefore, even if the engine continues to rotate due to inertia for a while after the start switch is turned off, the fuel supply can be stopped.
It is possible to reliably prevent the engine from starting.

According to such a configuration, as described above, when the automatic water spray signal W is at a high level and the switch 2 is switched to the automatic water spray mode, one input level of the AND circuit 14 becomes "0". , the application of the start signal ST to the OR circuit 6 is prohibited. At the same time, if the starting signal ST is being output, instead of the actual error signal E, a voltage at a level corresponding to the level of the signal E when the engine speed increases too much is output. This prevents the amount of fuel necessary to start the engine from being supplied, and this operation is continued for a predetermined time even after the output of the start signal ST is stopped by the delay circuit 19. start-up is reliably prevented.

Therefore, unlike in the past, it is possible to reliably prevent an accident in which the engine becomes overrun due to an erroneous operation such as forgetting to turn on the water pump at the time of starting.

According to the present invention, as mentioned above, it is possible to reliably prohibit the engine from starting in the automatic water spray mode, so that an abnormal increase in the engine rotational speed during startup due to an operational error such as forgetting to connect the water spray pump can be avoided. It is possible to reliably prevent the occurrence of such occurrences and to perform safe driving.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of a conventional electronic governor circuit for an internal combustion engine for a fire engine, and FIG. 2 is a block diagram of an embodiment of the present invention. 1... Electronic governor circuit, 2... Changeover switch,
3... Control signal generation circuit, 4... Accelerator position detection circuit, 5... Water discharge pressure setting and pressure detection circuit,
6...OR circuit, 7...drive circuit, 8...actuator, 11...electronic governor device, 12...starting protection circuit, 13...inverter, 14...AND circuit, 15...OR circuit, 16, 18...Diode, 17...Resistor, N...Speed signal, R...
...Rack position signal, W...Automatic water discharge signal, A...
Accelerator position signal, ST...starting signal, D...detection signal, _S1 ...control signal.

Claims (1)

[Scope of utility model registration request] An electronic governor device for an internal combustion engine for a fire engine, which is capable of switching from running speed control operation to water discharge pressure control operation upon application of an automatic water discharge signal, and also performs fuel adjustment operation for starting the engine in response to a starting signal. a first circuit that prohibits the start signal from being input to the electronic governor device while the automatic water discharge signal is applied; and a set water discharge pressure and an actual water discharge pressure generated in the electronic governor device. a second circuit that maintains a level of a signal indicative of the difference between the starting signal and the starting signal at a level below a level for providing a fuel supply amount necessary for starting the engine during the generation period of the starting signal; An electronic governor device for an internal combustion engine for a fire engine, comprising a delay circuit for continuing operation of the second circuit for a certain period of time.