JPS58110854A - Start assisting apparatus for diesel engine - Google Patents

Abstract

PURPOSE:To prevent deficiency of oxygen in a cylinder, by increasing the amount of fuel to be supplied to an intake-air heater in proportion to the engine speed in an apparatus for heating intake air by feeding fuel to an intake-air heater provided in an intake pipe and burning the same in the intake pipe. CONSTITUTION:With closing of a switch 14 at the time of starting an engine, an intake-air heater 13 is preheated and the engine is cranked. At the same time, a voltage E1 corresponding t the engine speed is impressed on an N-terminal 22. The voltage E1 is rectified at a rectifying integration circuit 21 and then sent to a pulse-width modulating circuit 19, which in turn produces an output signal having a pulse width T1 proportional to the voltage E1. For this while T1, a relay 17 is closed and a solenoid valve 10 is opened, so that fuel is supplied from a feed pump 2 to the intake-air heater 13. Subsequently, when the engine causes complete combustion and the engine speed is raised, the relay 17 is closed for a period corresponding to the pulse width proportional to the engine speed.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an auxiliary device for improving starting performance of a diesel engine.

Traditionally, it has been used as a starting aid for diesel engines in cold weather.
Devices using intake air heating are widely known.

As this intake air heating device, a combustion type heater is known that heats the intake air by burning the fuel in the intake pipe by making the fuel red-hot with electric heat and dripping it into the nine heaters.

Conventionally, the amount of fuel supplied to this combustion type heater remains constant regardless of the engine speed, so if the engine speed is low and the intake airflow is slow, KIIi, the oxygen in the intake pipe will be absorbed by the combustion of the heater. As a result, the inside of the cylinder of the engine becomes deficient in oxygen, and sufficient combustion does not take place within the cylinder, resulting in poor startability of the engine.

Further, if the amount of fuel supplied to the combustion type heater is reduced to such an extent that the oxygen concentration within the cylinder is not insufficient, there is a risk that the combustion flame will be blown out if the ignition of the heater is delayed.

The present invention improves this and improves startability by avoiding oxygen deficiency in the engine cylinder due to heater combustion, and assists in starting diesel engines in which the combustion flame of the stuttering heater is less likely to be blown out. The purpose is to provide equipment.

The present invention provides an electric circuit means for supplying a control current to a solenoid valve installed in an intake pipe of a diesel engine to open and close a pipe for supplying fuel to a multiplication combustion type heater. It is characterized by being equipped with a relay circuit that controls the flow rate of fuel passing through.

The present invention will be explained in detail below with reference to the drawings.

FIG. 1 is a block diagram of an apparatus according to an embodiment of the present invention. In FIG. 1, the lFi fuel injection pump, 2 is a feed pump, and 3 is a feed pump.
is a filter. Fuel in a fuel pipe 5 connected to a fuel tank (not shown) is passed through a feed pump 2 to a filter 3.
The fuel is sent to the fuel injection pump IK.

Fuel supplied to the fuel injection pump 1 is forced into a nozzle 6 by its plunger.

7Fi branch pipe, which supplies part of the fuel supplied from the filter 3 to the fuel injection pump 1 to the branch pipe 9.

This branch pipe 9 is connected via a solenoid valve 10 to an intake heater 13, which is a combustion type heater attached to an intake pipe 11. Further, a power source 15 is connected to the intake heater 13 via a switch 14 .

A characteristic configuration of the present invention resides in the control means for the solenoid valve 1G. That is, the switch 14 is connected to the solenoid valve 100 manually controlled by KFi and the relay 17 . The output of a pulse width modulation circuit 19 is connected to the relay winding 18 of this relay 17 . The response time toS of the stain ship 10 is determined by the clock signal sent from this pulse width variable circuit 19 at regular intervals.
If PIl is used, it will be reset every second. Further, the input of the pulse width modulation circuit 19 is connected to an N terminal 22 of an alternator (not shown) via a rectification/integration circuit 21. This N terminal 22
A voltage is generated that is proportional to the rotational speed of the engine.

With this configuration, the operation of this embodiment will be explained using the operation timing chart shown in FIG.

[Each symbol in FIG. 2 is an electrical signal waveform at the point indicated by the X mark in FIG.

First, when the switch 14 is closed, the intake heater 13 is preheated. On the other hand, when round cranking of the engine start motion is started and a voltage M1 corresponding to the engine rotational speed nIK is applied to the roof terminal 22 and rectified by the rectifier/integrator circuit 21 (Fig. 2(a)
)), this voltage E1 is applied to the output of the pulse width modulation circuit 19.
A signal with a pulse width T1 proportional to the magnitude of is sent out ((0) in FIG. 2), and the relay 17 is closed for this T1 time, the solenoid valve 10 is opened, and fuel is supplied to the intake heater 13.

Next, the engine enters a so-called continuous explosion state and the rotational speed decreases to nl.
to nz (nl<nz), this rotational speed n
2 is applied to the N terminal 22K, and similarly, a signal with a pulse width T2 proportional to the magnitude of this voltage Fi2 is sent to the output of the pulse width modulation circuit 19. As a result, the relay 17 is closed for 11 T2 time, the solenoid valve 10 is opened, and fuel is supplied to the intake heater 13.

When the rotational speed of the engine further increases to n3, fuel is similarly supplied to the intake heater 13 for a time T5 corresponding to the magnitude of the rotational speed n3.

In the above example, the H terminal of the alternator is connected to the input of the rectifier/integrator circuit, but it is also possible to connect the output of a rotation sensor that detects the rotational speed of the engine crankshaft as an electrical signal for fuel injection timing control. You may.

In addition, an example is shown in which a solenoid valve is controlled in two stages, opening and closing, using a rectifying and integrating circuit and a pulse width conversion circuit. It's better to control it.

As described above, according to the present invention, when the engine rotation speed is low, by providing a relay circuit that controls the opening time of the solenoid valve that supplies fuel to the intake heater in accordance with the engine rotation speed. , a small amount of fuel can be supplied to the intake heater to avoid oxygen deficiency in the cylinder, and when the engine speed increases, a large amount of fuel can be supplied to the intake heater to improve the intake air flow. It has nine excellent effects that can prevent the heater's combustion flame from blowing out even when the combustion speed increases.

[Brief explanation of the drawing]

FIG. 1 is a configuration diagram of an apparatus according to an embodiment of the present invention. Figure 2 also shows the operation timing chart of the relay circuit. 1...Fuel injection pump, 2...Feed pump, 3
... Filter, 5 ... Fuel pipe, 6 ... Nozzle, 7 ... Branch tube, 9 ... Branch pipe, 10 ... Solenoid valve, 11 ... Intake pipe, 13 ...・Intake heater, 14
-... Switch, 15... Power supply, 17... Relay,
18... Relay winding, 19... Pulse width modulation circuit,
21... Rectifier/integrator circuit, 22/-N terminal. Agent: Patent Attorney Nao Takashi Ide: “4.i.

Claims (1)

[Claims] (1) A combustion type heater installed in the intake pipe of a diesel engine, a solenoid valve that opens and closes a pipe that supplies fuel to this combustion type heater, and a control current applied to this solenoid valve and a current applied to the combustion type heater. A starting assist device for a diesel engine comprising an electric circuit means for applying electric heat, the electric circuit means comprising a relay circuit for controlling the flow rate of fuel passing through the solenoid valve in accordance with the rotational speed of the engine. A diesel engine starting aid device featuring: