JPH0423110B2 - - Google Patents

Description

[Detailed Description of the Invention] <Industrial Application Field> The present invention provides afterglow by energizing a glow plug provided in a diesel engine even after the engine is started in cold weather, but especially when the vehicle is running at a predetermined speed or higher. This invention relates to a preheating auxiliary device for a diesel engine that attempts to effectively utilize battery energy by stopping the engine.

<Conventional technology> When starting a diesel engine in cold weather, a glow plug installed inside the engine is rapidly heated to assist in starting. When the engine rotation speed is below a certain rotation speed, there is a problem that the engine noise (combustion noise) is large and white smoke is generated. Therefore, a method is known in which the glow plug is continuously energized for a certain period of time even after the engine has been started to heat the combustion chamber of the engine, which is called afterglow, to normalize fuel combustion and alleviate the above problem.

<Problems to be Solved by the Present Invention> However, in the conventional energization method, the battery capacity is limited due to continuous energization, and the battery cannot be energized for a long time. It has the disadvantage that energy is not used effectively.

As a technology that has already been disclosed in connection with the above, Japanese Patent Application Laid-Open No. 55-1463 discloses a starting device that uses a timer to energize a glow plug even after the diesel engine has started until the rotation stabilizes, and the engine speed energizes until the engine temperature reaches the set rotation speed (400rpm to 500rpm).
The plug preheating time before starting the engine is controlled by a timer, but the timer setting time changes depending on the engine temperature. The purpose of this device is to reduce combustion noise during low-speed, low-load rotation by energizing the flow plug during load rotation and advancing the ignition timing.The device energizes the flow plug when the engine is running at low speed and under low load even if the engine has been sufficiently warmed up. Also, JP-A-54-5143
According to the publication, the starting device increases the amount of fuel injection by energizing the glow plug using a timer until the rotation stabilizes even after the diesel engine starts,
The engine rotation speed is the set rotation speed (400 rpm ~
A device that energizes and increases the amount of fuel injection until the engine temperature reaches the set temperature (1500 rpm) or the engine temperature reaches the set temperature.
In addition, according to Japanese Utility Model Application Publication No. 54-52534, it is limited to diesel engines equipped with pneumatic governors, and focusing on the fact that the intake negative pressure is large when irregular combustion occurs after startup, the intake negative pressure is reduced by a pressure switch. A device that normalizes combustion, reduces noise and vibration, and purifies exhaust by energizing the glow plug if the negative pressure is above a set value, and also starts a diesel engine according to Japanese Patent Application Laid-Open No. 18459/1983. A device that energizes the glow plug even after the engine has started and continues to energize it until at least one of the engine speed and fuel injection amount exceeds a set value, in order to reduce noise and smoke emissions during engine operation. According to Publication No. 127878,
When idling after starting a diesel engine, there are devices that energize glow plugs to prevent knocking and reduce noise if the engine temperature is below a specified temperature. Most of the glow plugs are heated by energizing them based on the above information, and the setting values for energizing or stopping are provided independently based on this information, so it is difficult to provide the necessary and sufficient heating to the glow plug. However, it is difficult to use battery energy effectively.

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 can effectively utilize battery energy by stopping energization especially when the vehicle is running at a predetermined speed or higher.

<Means for Solving the Problems> To achieve the above object, the diesel engine preheating auxiliary device of the present invention rapidly preheats the glow plug 1 to a temperature sufficient for starting the engine, and rapidly maintains the glow plug 1 at the temperature. The heating control device 3 and the glow plug 1 are equipped with an afterglow relay 5 that afterglows for a predetermined time after the engine starts, and after the engine starts, a charging start signal of the charging generator, a signal indicating that the water temperature is below the set water temperature of the engine water temperature detector 10, and the engine are provided. High level until the first set speed is reached according to the signal from the vehicle speed detector 6, and when the second set speed is lower than the second set speed or less, according to the signal from the vehicle speed detector 6, on the condition that a signal indicating the rotation speed is below the set speed of the rotation speed detector 8 is input. The discrimination circuit 19 that emits a potential signal is connected to the afterglow relay 5 and the power source E ₀
An integration timer 17 is provided in between, which energizes the afterglow relay 5 only when the high-level potential signal is issued, and integrates the energization time, and outputs a signal when the integrated time reaches a set time. Alternatively, a control means is provided for stopping energization of the afterglow relay 5 in response to a signal from the discrimination circuit 19.

<Function> In the diesel engine preheating auxiliary device of the present invention having the above configuration, first, when the key switch 2 described later is turned on, current flows from the power source _E0 to the glow plug 1, and rapid heating of the glow plug 1 is started.
When the temperature reaches the preheating set temperature, the rapid heating control device 3 maintains the glow plug 1 at the set temperature, and then the key switch 2 starts the starter, but when the engine starts, the charging generator also rotates. When the output voltage reaches a chargeable potential, the normally closed contact 18 is opened in response to a charging start signal, and preparations are made to start afterglow.

When the engine water temperature is below the set water temperature, for example 60° C., the engine water temperature detector 10 is turned off, and no current flows through the discrimination circuit 19, resulting in a non-conducting state. Further, if the engine speed is below a predetermined value, the output signal from the engine speed detector 8 causes no current to flow through the discrimination circuit 19, making it non-conductive. With the above, all the necessary conditions for the afterglow of the discrimination circuit 19 are satisfied.

Next, if the traveling speed of the vehicle is lower than a second set speed (for example, 8 km/h), a high-level potential signal is generated from the discrimination circuit 19 based on the output signal of the vehicle speed detector 6, and the afterglow relay 5 is activated. It is excited, current flows to the glow plug 1, and afterglow starts. On the other hand, charging current also flows from the power source _E0 to the integration timer 17.

When the vehicle speed exceeds the first set speed (for example, 17 km/h), the potential signal from the discrimination circuit 19 becomes low level due to the output signal of the vehicle speed detector 6.
The afterglow relay 5 becomes inoperable, power to the glow plug 1 is cut off, and afterglow is stopped. Although charging of the integration timer 17 is stopped, the charged charge is retained.

When the vehicle decelerates and the vehicle speed becomes equal to or less than the second set speed, the afterglow relay 5 is activated and afterglow is performed in the same manner as described above. The above operation is repeated depending on whether the vehicle speed exceeds the range between the first set speed and the second set speed.

When the charge charged to the production timer 17 reaches a predetermined value, the afterglow relay 5 is deactivated regardless of the vehicle speed, and the glow plug 1 is turned off.
Cut off the power to.

<Example> Examples of the present invention will be described in detail.

When a diesel engine is cold, the unpleasant noise (diesel noise) and white smoke emitted from the engine are caused by the engine not being warmed up enough, and usually when the water temperature is below 50℃. It has been empirically confirmed that this occurs. Also, when the engine speed and vehicle speed exceed a certain speed (e.g. 8 km/h), this unpleasant clanging noise will become lower and will no longer cause discomfort to people, and the white smoke will no longer be emitted. This has also been confirmed empirically.

Therefore, the conditions for performing afterglow are a problem, and generally it needs to be performed under the following conditions.

(1) Engine water temperature is 60℃ (50℃ plus margin 10)
(2) The vehicle speed is below a certain speed. (3) The engine rotational speed is below a certain level. FIG. 2 is a circuit diagram used for such a preheating auxiliary device for a diesel engine.

In FIG. 1, E ₀ is a power source, generally from a vehicle-mounted battery. Reference numeral 1 denotes glow plugs, which are usually provided in correspondence with the number of cylinders in an engine, and the figure shows four glow plugs 1a, 1b, 1c, and 1d for a four-cylinder engine. 2 is a key switch, which has a fixed contact at the ON and START positions. Reference numeral 3 denotes a rapid heating control device for rapidly preheating the glow plug 1 to a temperature sufficient for starting the engine.When the key switch 2 is closed, the switch 4 is also closed to provide a large current to rapidly heat the glow plug 1 and preheat it. When the set temperature is reached, turn on/off switch 4 and turn on glow plusg 1.
The temperature is maintained at the preheating set temperature.
Re is a temperature detection resistor of the glow plug 1, and the control device 3 detects and controls the temperature of the glow plug 1 based on the voltage generated across the resistor Re. R ₁ is a voltage drop resistor, which is used to regulate the current flowing through the glow plug 1, and the afterglow current is supplied from the power source E ₀ to the glow plug 1 via this resistor R ₁ .

6 is a vehicle law detector, 7 is a comparator, and the second
As shown in the figure, the vehicle speed is 17km/h (first set speed)
When it exceeds the voltage, the potential at the output terminal e is set to a low level.
The characteristic is set to have hysteresis so that the level becomes high when the vehicle speed decreases from high speed to 8 km/h (second set speed). Further, _R14 is a variable resistor that adjusts the reference voltage of the comparator 7.

R ₃ is a resistor, C ₂ is a capacitor, and R ₃ and the capacitor C ₂ form a delay circuit 16 that delays the operation by about 4 seconds. The delay circuit 16 is provided to prevent hunting, and only when a certain vehicle speed continues for 4 seconds, for example, does the next operation take place, assuming that the conditions have been established. 13
is a comparator, R ₄ and R ₅ are resistors, and this resistor
R ₄ and R ₅ determine the reference voltage of the comparator.
In addition, R is the potential accumulated in the above capacitor _C2 ,
A resistor for discharging when key switch 2 is OFF.
It can also be omitted.

C ₃ is a capacitor, R ₂ is a resistor, and the capacitor C ₁ and resistor R ₂ form an integration timer 17 that integrates the afterglow time as described later. The integration timer 17 measures the time until the vehicle speed reaches 17 km/h (first set speed) and the time when the vehicle speed drops below 8 km/h (second set speed) during afterglow after engine startup. It is a discrimination circuit that integrates the time and when it reaches 3 minutes, for example.
Afterglow relay 5 of glow plug 1 is opened via AND circuit 19. The integration time of the integration timer 17 is determined by the values of the resistor R ₂ and the capacitor C ₁ , and is set to about 3 minutes in relation to the battery capacity.

12 is a comparator, R ₁₁ and R ₁₂ are resistors that determine the reference voltage, and comparator 1
The output terminal of 2 is connected to diode _D5 . D ₁
is a diode, which prevents reverse current from the capacitor _C1 . _D2 is also a diode,
When the potential at the output terminal e of the comparator 7 is at a low level, that is, when the vehicle speed is 8 km/h (second set speed) or higher, a current is passed to the output terminal a of the comparator 13, and the comparator 7 Output end e
This is to prevent current from flowing from point a to point b of the integration timer 17 when the point is at a high level and the vehicle speed is less than 8 km/h.
R ₆ , R ₇ , R ₈ , R ₉ , R ₁₀ are resistances, and a
This is to provide an appropriate bias voltage to the transistors Tr ₁ and Tr ₂ . 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 Zener diode to protect transistor _Tr2 from surge voltage.

8 is an engine rotation speed detector that detects the engine rotation speed, and 9 is a comparator. If the output of the rotation detector is below a certain value, the potential at the output end point b becomes high level, and the value It is set so that when it exceeds this value, it will be reversed and become a low level.
R ₁₅ and R ₁₆ are resistors that reduce the reference voltage of the comparator 9.

20 is a timer that ANDs the engine speed signal from the engine speed detector 8 for about 15 seconds after the engine starts even if the engine speed exceeds a predetermined value.
The electric potential at point f is maintained at a high level without being transmitted to the rotation 19, and during this period, the rapid heating control device 3 and the switch 4 repeat the rapid heating and then the rapid reheating and shutoff after the rapid heating.

10 is a thermoswitch which is an engine water temperature detector for detecting the engine water temperature, and is set to turn on at 60°C when the water temperature rises and turn off at 50°C when the water temperature falls.

Reference numeral 18 is a contact point of the charging relay, which is connected to the AND circuit 19. When the engine starts and the output voltage of the charging generator reaches a charging potential, it is opened and the connection point with the AND circuit 19 is raised. It is a normally closed contact point that establishes a system for afterflow as a level. Diodes D ₃ , D ₅ , D ₆ , D ₇ , D ₉ in the diagram
forms one AND circuit 19, and this AND circuit 19 forms a determination circuit for determining whether the conditions for performing afterglow after starting the engine have been met.

Next, the operation of the above circuit will be explained.

First, when the key switch 2 is turned to the ON position, current flows from the power source E ₀ to the switch 2 to the switch 4 to the temperature detection resistor Re to the glow plug 1, and rapid heating of the glow plug 1 is started. When the temperature of the glow plug 1 reaches the preheating set temperature, the switch 4 is turned on and off by the action of the glow plug rapid heating control device 3 to maintain the glow plug at the set temperature (approximately 900° C.). When the key switch 2 is then turned to the start position ST, a starter relay (not shown) is activated and a starter (not shown) is activated. When the engine starts and you release your hand from key switch 2, key switch 2
Recovery rotation to ON position. Further, when the engine starts, a charging 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 prepares the system for afterglow to begin.

When the engine water temperature is below 60° C., the thermoswitch 10 is opened, and the potential at point g is maintained at a higher level than the potential at point k, and no current flows through diode _D7 , resulting in a non-conducting state. Furthermore, if the engine speed is below a predetermined value, the output signal of the engine speed detector 8 causes the potential at the output terminal f of the comparator 9 to be held at _a higher level than the potential at the k point. No current flows and it becomes non-conductive. Furthermore, as described above, the same applies even if the engine speed exceeds a predetermined value set by the timer 20 for about 15 seconds after the engine is started. As a result, the AND circuit 19
This means that all the necessary conditions for afterglow have been met.

Next, when the traveling speed of the vehicle is the second set speed, 8
If it is below Km/h, the output signal of the vehicle speed detector 6 is lower than the reference voltage determined by the resistor R ₁₃ and the variable resistor R ₁₄ , so the potential at the output terminal e of the comparator 7 is held at a high level. When the holding time exceeds the delay time (approximately 4 seconds) of the delay circuit 16, a high potential input is applied to the + side of the comparator 13, and the potential at the output terminal a becomes high enough to drive the transistor _Tr1 . held at the required high potential. As a result, the transistors Tr ₁ and Tr ₂ become conductive, and the conduction of Tr ₂ causes the operating coil 5b of the afterglow relay 5 to become conductive.
is excited. The normally open contact 5a is closed by the operation of the relay 5, and the power supply E ₀ → switch 2 → normally open contact 5a → voltage drop resistor R ₁ → temperature detection resistor Re →
A current flows through the glow plug 1 and afterglow starts. On the other hand, a charging current flows through the capacitor C ₁ from the power source E ₀ via the resistor R ₂ and the diode D ₁ while the potential at point a is high.

When the vehicle speed exceeds the first set speed of 17 km/h, the potential at the output terminal e of the comparator 7 becomes a low level, and after a delay of the delay time of the delay circuit 16, a low potential is applied to the + side of the comparator 13. An input is applied, and its output terminal point a is held at a low potential level. When the potential at point a becomes low level, transistors Tr ₁ and Tr ₂ are opened, the afterglow relay 5 becomes inoperable, and its normally open contact 5
Since a is opened, the power to the glow plug 1 is cut off, and afterglow is stopped. 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. However, even if the potential at point b drops, the charge in the capacitor _C1 will not be discharged because of the presence of the diode _D1 .

When the vehicle decelerates and the vehicle speed becomes 8 km/h or less, the transistors Tr ₁ and Tr ₂ become conductive and the afterglow relay 5 is activated to perform afterglow, as described above. Vehicle speed is 8km/h~
The above operation is repeated depending on whether or not the speed exceeds the 17 km/h range, and as the capacitor _C1 is charged, the potential at point C gradually increases, and the negative potential of the comparator 12 becomes higher than the positive potential. When it gets high,
Since the output terminal point d of the comparator 12 has a low level potential, the potential at the k point also becomes low and Tr ₁ , Tr ₂
becomes non-conductive, the afterglow relay 5 becomes inoperable, and the power supply to the glow plug 1 is cut off. In this case, even if the vehicle speed becomes 8 km/h or less, the glow plug 1 is no longer energized and no afterglow occurs.

A timing chart for explaining the above circuit operation is shown in FIG. 3. In the figure, T ₁ indicates the delay time of the delay circuit 16.

<Effects of the Invention> As described above in detail, the diesel engine preheating auxiliary device according to the present invention rapidly preheats the glow plug 1 to a temperature sufficient for starting the engine and maintains the glow plug at that temperature. The control device 3 and the glow plug 1 are equipped with an afterglow relay 5 that afterglows for a predetermined period of time after the engine starts, and after the engine starts, a charging start signal of the charging generator, a signal indicating that the water temperature is below the set water temperature of the engine water temperature detector 10, and the engine rotation are provided. On the condition that a signal is input indicating that the rotation speed is below the set rotation speed of the vehicle speed detector 8, the rotation speed is changed until the first set speed is reached and the second speed lower than the speed is reached according to the signal of the vehicle speed detector 6.
The afterglow relay 5 includes a discrimination circuit 19 that issues a high-level potential signal when the speed drops below a set speed.
and a power supply _E0 , and energizes the afterglow relay 5 only when the high-level potential signal is generated, and an integration timer 17 that integrates the energization time, and the integrated timer 17 is provided between the power supply E Since the controller is provided with a control means for stopping the energization to the afterglow relay 5 in response to a signal output at the time or a signal from the discriminating circuit 19, the energization time of the afterglow relay 5 is stopped until the cumulative amount of energization time by the integration timer 17 reaches a predetermined value. In order to obtain smooth engine rotation, preheating can be performed when the vehicle is running at low speed when the engine water temperature is below 60℃ and the engine rotation speed is below a certain level, which requires preheating for smooth engine rotation. This has the effect that the afterglow of the battery can be effectively performed, and the amount of current that is limited by the battery capacity can be used more effectively.

In addition, since the discrimination circuit 19 is configured to emit each signal when the vehicle speed is at the first set speed and when the second set speed is lower than the first set speed, it is possible to perform necessary and sufficient afterglow according to the increase or decrease of the vehicle speed. There is also.

[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 operating range of the comparator connected to the vehicle speed detector, and Fig. 3 is a diagram for explaining its operation. This is a timing chart. 1...Glow plug, 2...Key switch, 3
... Glow plug rapid heating control device, 4 ... Switch, 5 ... Afterglow relay, 6 ... Vehicle speed detector, 8 ... Rotation detector, 10 ... Water temperature detector, D ₁ to D ₄ ... Diode, D ₁₀ ... Zener diode, 16 ... Delay circuit, 17 ... Integration timer, 18 ... Charging relay contact, 19 ... AND
Circuit, 20... Timer, 7, 9, 11, 12,
13... Comparator, R ₁ ~ R ₁₈ ... Resistor,
C ₁ , C ₂ ... Capacitor, Re ... Temperature detection resistor.

Claims (1)

[Claims] 1. A rapid heating control device 3 for rapidly preheating the glow plug 1 to a temperature sufficient for starting the engine and maintaining it at that temperature, and an afterglow for causing the glow plug 1 to afterglow for a predetermined period of time after starting the engine. A relay 5 is provided, and after the engine is started, a charging start signal from the charging generator, a signal from the engine water temperature detector 10 indicating that the water temperature is below the set temperature, and a signal indicating that the engine speed is below the set rotation speed from the engine speed detector 8 are input. A discrimination circuit 19 is provided between the afterglow relay 5 and the power source _E0 , which emits a high-level potential signal until the vehicle speed reaches a first set speed and when the speed drops below a second set speed, in response to a signal from the vehicle speed detector 6. an integration timer 17 is provided, which energizes the afterglow relay 5 only when the high-level potential signal is emitted, and integrates the energization time, and outputs a signal when the integrated time reaches a set time; A preheating auxiliary device for a diesel engine comprising a control means for stopping energization to the afterglow relay 5 in response to a signal from a discrimination circuit 19.