JPH0121350B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a preheating auxiliary device for a diesel engine that effectively utilizes battery energy by energizing a glow plug of a diesel engine even after the engine is started, but stopping energization while the vehicle is running.

Diesel engines have the problem of making loud engine noise and producing white smoke if the engine speed is below a certain speed immediately after starting, but the glow plug remains constant even after starting. A method is known in which the above-mentioned problem is alleviated by heating the combustion chamber of the engine by continuously supplying electricity for a certain period of time to normalize fuel combustion. However, conventional energization methods have the disadvantage that they require continuous energization, which limits the battery capacity and cannot energize for long periods of time, and that battery energy is not used effectively because the current is energized even when the vehicle is running, which does not require energization. ing. As for the technology that has already been disclosed, the engine rotational state is detected by the throttle opening according to Japanese Utility Model Application Publication No. 56-55723, and when the engine is running at low speeds, the glow plug is energized to advance the ignition timing, thereby reducing noise at low speeds. The purpose is to reduce the
There is a device that energizes the engine even if it is warmed up sufficiently if it rotates at low speed, and Japanese Patent Application Laid-Open No. 1463/1983 describes a starter device that energizes the plug even after the diesel engine has started until the rotation stabilizes. The engine rotation speed is the set rotation speed (400rpm to 1500rpm)
A device that energizes until the engine temperature reaches a set temperature and is controlled by a plug preheating timer before starting the engine, but the timer setting time changes depending on the engine temperature.
- Publication No. 114877 states that even after rapid preheating of the glow plug before starting the engine, a warming current is passed through the glow plug to maintain the plug temperature at a constant value, and when the starter motor is activated, a resistor connected in series with the plug is short-circuited. This eliminates the voltage drop to the plug caused by the starter motor, and the plug continues to be energized even after the engine starts, but if any increase in engine speed, battery voltage, exhaust temperature, or engine temperature is detected, the short circuit of the above resistor is released. Japanese Patent Laid-Open No. 101771/1983 discloses a device that reduces the voltage applied to the plug to prevent overheating, and a device that reduces the voltage applied to the glow plug to prevent overheating. After energization, there is a heat retention period in which the energization is switched to intermittent energization.Each energization time is determined by the charging time of the capacitor in the control circuit, and if the engine temperature exceeds the set value, the temperature switch is turned on and the charging time changes. There are devices that shorten the energization time, but none of them can solve the above drawbacks.

SUMMARY OF THE INVENTION The present invention has been made in view of the above points, and an object of the present invention is to provide a preheating auxiliary device for a diesel engine that reduces battery capacity limitations and effectively utilizes energy.

Next, embodiments of the present invention will be described in detail using drawings and the like.

During the cold period of a diesel engine, the engine makes an unpleasant clanking sound and emits white smoke because the engine is not warmed up enough, and it has been experienced that it is usually emitted when the water temperature is below 60 degrees Celsius. It has been confirmed that Also after starting the engine 14
~ If the engine speed exceeds a certain value after 15 seconds or if the vehicle's running speed reaches a certain speed (8 km/h)
h) It has been empirically confirmed that when the above is reached, the unpleasant clanging noise becomes low enough to not cause discomfort to people, and that white smoke is no longer emitted. Therefore, the conditions for performing afterglow are a problem, and generally it is necessary to perform it under the following conditions.

(1) The sound of water is below 60℃ (2) The vehicle speed is below a certain speed (3) The engine is in an idling state (when waiting at a traffic light after starting the vehicle, etc.). FIG. 2 is a circuit diagram used in a diesel engine preheating auxiliary device for performing afterglow that satisfies conditions. In FIG. 1, Eo is a power source, generally consisting of a vehicle battery. 1
are glow plugs, which are usually provided according to the number of cylinders in the engine, and in the figure, four glow plugs 1a, 1b, 1c, and 1d for a 4-cylinder engine are shown.
It shows. 2 is the key switch, turn on,
It has a fixed contact at the start ST position. 3
is a rapid heating control device for a glow plug. At the same time as the key switch 2 is closed, the switch 4 is closed to heat the glow plug 1. When the preheating set temperature is reached, the switch 4 is turned on and off to control the temperature of the glow plug. This is to maintain the preheating temperature at the preset temperature. Re is the temperature detection resistance of glow plug 1, and this resistance
The control device detects and controls the temperature of the glow plug based on the voltage generated across Re. R ₁ is a voltage drop resistor for regulating the current flowing through the glow plug 1, and afterglow current is supplied from the power supply to the glow plug 1 via this resistor R ₁ . GSW is a gear position switch, and ASW is an accelerator pedal switch.
By connecting the GSW and the accelerator petal switch ASW in series, a simulation circuit 15 representative of running and stopping modes is formed, and afterglow is performed. R ₃ is a resistor, C ₂ is a capacitor, this resistor R ₃
Delay circuit 1 for about 4 seconds with capacitor C ₂
form 6. 13 is a comparator, R ₄ , R ₅
is a resistor, and this resistor R ₄ and R ₅ comparator 1
Determine the reference voltage of step 3. C ₁ is a capacitor, R ₂
is a resistor, and this capacitor C ₁ and resistor R ₂ form an integration timer 17 that integrates the afterglow time as described later. The integration time of integration timer 17 is determined by the values of resistor R ₂ and capacitor C ₁ ,
Due to the relationship with the battery capacity, it should be about 3 minutes. 1
2 is a comparator, R ₁₁ and R ₁₂ are resistors that determine its reference voltage, and the output terminal of the comparator 12 is connected to a diode D ₅ . _D1 is a diode to prevent reverse current from capacitor _C1 . _D2 is also a diode, and when both the gear position switch GSW and the accelerator pedal switch ASW are closed, so-called vehicle driving mode, current flows to the output terminal a point of the comparator 13, and one of them is open. This is to prevent current from flowing from point a to point b of the integration timer 17 when the timer is in the stop mode. R ₆ , R ₇ , R ₈ , R ₉ , and R ₁₀ are resistors, respectively, and point a and transistors Tr ₁ and Tr ₂
The purpose is to apply an appropriate bias voltage to the Tr ₂ is a transistor for driving the afterglow relay 5. Tr ₁ is also a transistor and is used to drive transistor Tr ₂ . _D10 is a transistor and _Tr2 is a Zener diode to protect from surge voltage. 8 is a rotation detector that detects the rotational speed of the engine, and 9 is a comparator. If the output of the rotation detector is below a certain value, the potential at the output terminal f becomes a high level, and when it exceeds that value, it is reversed. It is set to a low level. Reference numeral 20 denotes a timer, which generates an output for about 15 seconds after the engine is started even if the number of engines exceeds a predetermined value, so that the potential at point e does not fall to a low level. In other words, afterglow occurs for about 15 seconds after the engine starts, even if the engine speeds up. R ₁₅ and R ₁₆ are resistors that determine the reference voltage of comparator 9, 10 is an engine water temperature detector,
10 is a thermo switch that detects the water temperature of the engine, and is set to open when the water temperature is below 60°C and close when it exceeds 60°C, but the value differs slightly depending on the model. 18 is a contact of a charging relay, which is a normally closed contact that is activated and opened when the engine is started and the output voltage of the generator reaches a charging potential. Diodes D ₃ , D ₅ , D ₆ , D ₇ , and D ₉ form one AND circuit 19 . This AND circuit becomes a gate circuit that determines whether the conditions for afterglow after engine startup have been met.

Next, the operation of the above circuit will be explained. First, when the key switch 2 is turned to the start ST position, a current flows from the power source Eo to the key switch 2 to the switch 4 to the temperature detection resistor Re to the glow plug 1, and rapid heating of the glow plug starts. When the glow plug 1 reaches the set temperature, the glow plug rapid heating control device 3 turns the switch 4 on and off to set the temperature of the glow plug 1 to the set temperature (approximately 900°C).
At the same time, the starter relay (not shown) is activated and the starter (not shown) is activated. When the engine starts, release the key switch 2 and the key switch 2 will return to the ON position. Further, when the engine starts, a generator (not shown) also rotates, and when the output voltage reaches a charging potential, the charging relay is activated and its normally closed contact 18 is opened. This sets the stage for the start of afterglow. When the engine water temperature is below 60°C, the thermoswitch 10 is opened, and no current flows through the diode _D7 , resulting in a non-conducting state. Further, if the engine speed is below a predetermined value, the potential at the output terminal f of the comparator 9 is maintained at a high level by the output signal of the rotation detector 8. As mentioned above, for 15 seconds after the engine is started, the potential at point e is maintained at a high level by the timer 20 even if the rotational speed exceeds a predetermined value. When the potential at point e is held at a high level, no current flows through the diode _D6 and it becomes non-conductive.
This satisfies all the conditions necessary for the afterglow of the AND circuit 19. Next, by connecting the gear position switch GSW and the accelerator pedal switch ASW in tandem, as shown in Figure 2, the running and stopping modes of the vehicle are simulated, and afterglow is performed only in the stopping mode. In the stop mode, that is, when both the gear position switch GSW and the accelerator pedal switch ASW are released, or when either one is released, the comparator 13 is activated after the delay time of the delay circuit 16 (approximately 4 seconds) from the time of release. An input is applied to the + side of the
The point is held at a high potential necessary to drive transistor _Tr1 . This allows the transistor
Tr ₁ and Tr ₂ are brought into conduction, and the activation coil 5b of the relay 5 is excited by the conduction of Tr ₃ . Activation of relay 5 closes its normally open contact 5a, and power supply E ₀ → key switch 2 → voltage drop resistance R ₁ → relay contact 5a →
Current flows from temperature detection resistor Re to glow plug 1, and afterglow begins. On the other hand capacitor
While the potential at point a is high, a charging current flows through C ₁ from the power supply via resistor R ₂ and diode D ₁ . In the case of driving mode, that is, when both the gear position switch GSW and the accelerator pedal switch ASW are closed, the comparator 1 is
The + side of 5 is grounded, and point a is held at a low level potential. When the potential at point a falls to a low level, transistors Tr ₁ and Tr ₂ are opened, relay 5 becomes inactive, and its contact 5a is opened, so that power to glow plug 1 is cut off and afterglow is discontinued. On the other hand, as the potential at point a decreases, the potential at point b also decreases, so charging of the capacitor _C1 is stopped. Furthermore, even if the potential at point b decreases, the charge in the capacitor _C1 will not be discharged because of the presence of the diode _D1 . Subsequently, in the stop mode, the transistors Tr 1 , Tr ₁ ,
Tr ₂ becomes conductive, relay 5 is activated, and afterglow is performed. As the running mode and stop mode described above are repeated and the capacitor _C1 is charged, the potential at point C gradually increases, and when the one side input potential of the comparator 12 becomes higher than the + side input terminal potential, the comparator 12 Since the output terminal point d is at a low level potential, the transistors Tr ¹ and Tr ₂
becomes non-conductive, the relay 5 becomes inactive, and the power to the glow plug is cut off. In this state, no afterglow occurs even if the mode represented by the combination of the accelerator pedal switch ASW and gear position switch is in the stop mode. The timing chart explaining the above rotation operation is shown in the third section.
As shown in the figure. In the figure, T ₁ indicates the delay time of the delay rotation 16.

Note that the combination of gear position switch GSW and accelerator pedal switch ASW is different from the cascade connection shown in Fig. 1, for example,
Methods of using only one of the gear position switch or accelerator switch, methods of parallel connection instead of cascade connection, method of using a separate switch in addition to the two switches (e.g. clutch switch)
There is also a method of adding them and connecting them in tandem or in parallel.

As explained above in detail, the diesel engine preheating auxiliary device according to the present invention is capable of starting charging from the generator to the battery after the engine starts, and after-glow when the engine water temperature is below 60°C and the engine speed is below a certain value. When these conditions are met, the gear position switch and accelerator pedal switch are combined to represent the vehicle's running mode and stop mode, and energizes the glow plug only in the stop mode to perform afterglow and turn the glow plug on. The energization time is accumulated by the integration timer, and when the energization time exceeds the time set on the integration timer, the energization is cut off and the afterglow is stopped, so that the accumulated amount of energization time by the integration timer reaches the predetermined value. Until this point is reached, it is possible to preheat the engine when preheating is required for smooth engine rotation, and it is possible to effectively perform afterglow to obtain smooth engine rotation.
This device exhibits an excellent effect that cannot be found in conventional diesel engine preheating auxiliary devices, as it allows more effective use of the amount of current that is limited by battery capacity.

[Brief explanation of drawings]

Fig. 1 is a circuit diagram used in the diesel engine preheating auxiliary device according to the present invention, Fig. 2 is a diagram showing the distinction between running and stopping, and Fig. 3 is a timing chart for explaining the circuit operation of Fig. 1. It is. 1...Glow plug, 2...Key switch, 3
... Glow plug rapid heating control device, 4 ... Switch, 5 ... Afterglow relay, 8 ... Rotation detector, 10 ... Thermoswitch, D ₁ to D ₉ ... Diode, D ₁₀ ... Zener diode , 15...
...Running, stop mode simulation circuit, 16...Delay circuit, 17...Integration timer, 18...Charging relay contact, 19...And circuit, 9, 11, 12,
13...Comparator, GSW...Gear position switch, ASW...Accelerator pedal switch, _R1 to _R16 ...Resistor, _C1 , _C2 ...Capacitor, Re...Resistance for temperature detection.

Claims (1)

[Claims] 1. In the preheating auxiliary device that energizes the glow plug even after the diesel engine has started, there is a switch that detects when to start pressing the accelerator pedal and outputs a signal, a switch that detects when the gear shift is in a state other than neutral and outputs a signal, and the above-mentioned switch. A diesel engine characterized in that it has an integrating means for integrating the energization time and outputting a signal when the set time is reached, and a control means for inputting at least one signal from the two switches and the integrating means to stop the energizing. Preheating auxiliary device.