JP3463702B2 - Fuel supply control device for internal combustion engine - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fuel supply controller for an internal combustion engine, which is suitable for controlling the supply of fuel to an internal combustion engine, especially a diesel engine.

[0002]

2. Description of the Related Art In a diesel engine which supplies fuel by using a fuel injection pump, a fuel supply control device having an electromagnetic valve which is on / off controlled by a solenoid is provided, and the electromagnetic valve is opened when the engine is in operation. The fuel can be supplied from the injection pump, and the electromagnetic valve is closed to stop the fuel supply from the fuel injection pump to stop the engine.

FIG. 5 shows the structure of a fuel supply control device of this type which has been already proposed. In FIG. 5, 1 is a battery as a power source, 2 is a key switch, 3 is a fuel supply control solenoid, and 4 is a fuel supply control solenoid. Is a starter for starting the internal combustion engine, 5
Is a fuel injection pump, 6 is a diesel engine, 7 is a time circuit, and 10 is a switch circuit including a relay exciting switch 8 and a relay 9. The key switch 2 includes a movable contact 2a operated by a key (not shown) and an off contact 2b with which the movable contact 2a contacts when the engine is stopped (power is off).
And a contact 2c for energization during operation, which contacts the movable contact 2a during operation of the engine, and a contact 2d for energization during startup, which contacts the movable contact 2a only when the engine is started.
In this key switch, when the key is turned one step from the off state, the movable contact 2a first comes into contact with the energizing contact 2c during operation, and when the key is further turned one step, the movable contact 2a is energized during operation. The contact 2c is kept in contact with the contact 2d for energization at the time of starting. When the key is released in this state, the movable contact 2a automatically returns to the state in which only the contact 2c for energization during operation is contacted by the urging force of the return spring.

The fuel supply control solenoid 3 is a coil for driving the fuel supply valve. The pull coil 3a is excited when the valve is opened, and the fuel supply control solenoid 3 is kept in an excited state during operation of the engine in order to keep the valve open. Hold coil 3
b. One ends of the pull coil 3a and the hold coil 3b are commonly connected and grounded, the other end of the pull coil 3a is connected to the energization contact 2c during operation via the switch circuit 10, and the other end of the hold coil 3b is directly energized during operation. They are respectively connected to the contacts 2c. Battery 1
→ key switch 2 → switch circuit 10 → pull coil 3a
→ The circuit of battery 1 constitutes a pull coil energizing circuit, and battery 1 → key switch 2 → hold coil 3b
→ The circuit of the battery 1 constitutes a hold coil energizing circuit.

The starter 4 comprises a starter motor 4a and an electromagnetic switch 4b for energizing the motor, and the non-grounded side terminal of the starter motor is a contact 4b1 of the electromagnetic switch.
Is connected to the non-grounded side terminal of the battery 1 through. One end of the exciting coil 4b2 of the electromagnetic switch is grounded,
The other end is connected to the starting energizing contact 2d. When the movable contact 2a of the key switch contacts the energizing contact 2d at the time of starting, the exciting coil 4b2 is energized from the battery 1,
Contact 4b1 closes. As a result, from the battery 1 to the contact 4b1
The starter motor 4a is energized to rotate the engine 6. When the engine is rotated, the fuel injection pump 5 operates to supply the fuel and the engine 6 starts.

The time limit circuit 7 includes a timer capacitor C1 and
It is composed of diodes D1 to D3, resistors R1 to R3, and a zener diode Z1. The switch circuit 10 is composed of a relay exciting switch 8 including a field effect transistor (FET) F1 and a diode D4, an exciting coil 9a, and a relay 9 having a contact 9b which is closed when the exciting coil is excited. There is.
The time limit circuit 7 and the switch circuit 10 allow the fuel to be supplied at the same time as the starter motor 4a rotates to improve the startability, prevent wasteful consumption of the battery 1, and take time to start the engine. Pull coil 3
It is provided to prevent a from being burnt out, and the time circuit 7 starts the timed operation at the same time as the contact 2c for energizing the operation time of the key switch is connected to the battery 1, and the set operation is performed. Only during the time period, the relay contact 9b is closed and the pull coil 3a is energized.

The above circuit operates as follows. That is,
When the movable contact 2a of the key switch is brought into contact with the energizing contact 2c during operation, a current flows from the battery 1 to the hold coil 3b through the key switch, and at the same time, battery 1 → key switch 2 → diode D1 → resistor R2 → capacitor C1. → Resistor R3 → Current flows in the path of battery 1 and capacitor C1 is charged. At this time, the voltage generated across the resistor R3 is applied between the gate and source of the FET F1, so that the FET becomes conductive and the battery 1 → key switch 2 → diode D1 → excitation coil 9a → FET F1.
1 → A current flows in the path of the battery 1 to excite the exciting coil 9a. As a result, the contact 9b is closed and the pull coil 3
When a is energized, the fuel supply valve provided in the fuel injection pump 5 opens. Next, the movable contact 2 of the key switch
When a contacts the energizing contact 2d at the time of starting, the starter motor 4a is activated. At this time, the fuel injection pump 5 is already in a state where it can supply fuel, so the fuel is supplied to the engine at the same time as the starter motor rotates, and the engine starts.

When charging of the capacitor C1 progresses and the voltage across the capacitor C1 reaches a certain level, the Zener diode Z1
Is charged, the charging of the capacitor C1 is completed (timed operation is completed). Therefore, no current flows through the resistor R3, the voltage between the gate and source of the FET F1 becomes zero, and the FET is cut off. As a result, the relay 9 is deenergized, the contact 9b is opened, and the power supply to the pull coil 3a is stopped. The operation time limit of the time limit circuit can be appropriately set by adjusting the time constant determined by the capacitor C1 and the resistance values of the resistors R2 and R3. This operation time limit is within the allowable rated energizing time (usually about 3 seconds) of the pull coil 3a. Is set to. When the key switch 2 is opened, the electric charge of the capacitor C1 is discharged with a constant time constant through the discharging circuit of the diode D2 → the resistor R1 → the diode D3 → the capacitor C1 and returns to the original state.

[0009]

In the above fuel supply control device, when the movable contact 2a of the key switch is brought into contact with the energizing contact 2c during operation, the timed operation is started to energize the pull coil 3a, and the timer capacitor is connected. When the voltage across C1 reaches a constant value (Zener level of Zener diode Z1) and the timed operation ends, the energizing current of the pull coil 3a is cut off. However, when the movable contact 2a of the key switch subsequently contacts the energizing contact 2d at the time of starting and a large current flows through the starter motor 4a, the terminal voltage of the battery 1 drops extremely due to the discharge of this large current. When the state of the battery is bad, the voltage of the 12V type battery may drop to about 5V, for example. Therefore, even when the key switch 2 is not opened, the charge of the capacitor C1 charged to a constant voltage is not reduced by the diode D1 →
It discharges through the discharge circuit of resistance R1-> diode D3-> capacitor C1. When the energizing current of the starter motor decreases and the terminal voltage of the battery 1 recovers, the charging current flows through the capacitor C1 again. Capacitor C1
The current of the pull coil 3a is cut off when the charging of
When the movable contact 2a of the key switch returns to the state of contacting only the energizing contact 2c during operation and the energization of the starter motor ends, the terminal voltage of the battery 1 further rises and returns to the original state. Therefore, the charging current may flow again to the capacitor C1 and the pull coil 3a may be re-energized. In this way, the pull coil 3a may be repeatedly energized several times and the allowable energization time may be exceeded.
There was a risk that a would be overheated and burned.

It is an object of the present invention to prevent the timed operation of the timed circuit from being restarted and the energization of the pull coil to be restarted when the terminal voltage of the battery is lowered due to the energization of the starter motor, and the overheating of the pull coil, An object of the present invention is to provide a fuel supply control device for an internal combustion engine, which prevents burnout.

[0011]

SUMMARY OF THE INVENTION A fuel supply control device for an internal combustion engine according to the present invention includes a contact for energization during operation which is maintained in a state of being connected to a power source during operation of the internal combustion engine and a power source for starting the internal combustion engine. A key switch having a start-up energizing contact connected thereto, a pull coil excited to open the fuel supply valve when the internal combustion engine is started, and a hold coil excited to hold the valve in an open state. The fuel supply control solenoid is provided, and the timer switch is equipped with a timer capacitor that is charged with a constant time constant by the output of the power supply when the operating contact of the key switch is connected to the power supply. The time limit circuit for which the operating time is the time, and the pull coil that energizes the pull coil through the switch circuit that closes only while this time circuit is performing the time operation The circuit and the hold coil energizing circuit that energizes the hold coil of the solenoid from the power supply through the energizing contact of the key switch during operation, and the discharge of the timer capacitor while the energizing contact of the key switch during operation is connected to the power supply And a reset circuit that configures the discharge circuit of the timer capacitor and resets the time circuit when the contact for energizing the key switch during operation is disconnected from the power supply. The operation time limit of the time limit circuit is set to be equal to or less than the allowable rated energization time of the pull coil.

The reset circuit can be composed of a relay having an exciting coil to which a voltage of a power source is applied through a contact for energizing during operation, and a normally closed contact which opens when the exciting coil is excited. In this case, the normally closed contact of the relay is connected in parallel to the timer capacitor, and the normally closed contact constitutes a discharge circuit of the timer capacitor.

The reset circuit is also connected in parallel to the timer capacitor and a reset circuit power supply capacitor charged by the output voltage of the power supply when the energizing contact during operation is connected to the power supply. The semiconductor switch for reset, which is supplied with a drive signal by the electric charge accumulated in the power supply capacitor for conduction, and the contact for energization during operation are connected to the power supply, and the supply of the drive signal to the semiconductor for reset is blocked. Alternatively, it may be configured by a circuit including a reset switch control circuit that permits the supply of the drive signal to the reset semiconductor switch when the operating energizing contact is disconnected from the power supply.

[0014]

As described above, the discharge of the timer capacitor is prevented while the operating contact of the key switch is connected to the power supply, and the timer is activated when the operating contact of the key switch is disconnected from the power supply. When the reset circuit of the time limit circuit is configured so that the discharge circuit of the capacitor is reset and the time limit circuit is reset, when the contact for energizing during operation is connected to the power supply, the starter motor starts and the power supply voltage drops. Even if the timer capacitor is not discharged,
When the power supply voltage rises again, the charging current does not flow in the timer capacitor and the timed operation is not restarted. Therefore, it is possible to prevent the energization of the pull coil from being resumed after the starter motor is started and the energization time to the pull coil exceeds the allowable range, and it is possible to prevent overheating and burning of the pull coil.

When the operating contact of the key switch is disconnected from the power supply, a discharge circuit is formed in the timer capacitor, and the charge of the timer capacitor is discharged through the discharge circuit. Therefore, the time circuit is reset to the original state. It
Therefore, the next time the engine is started, the pull coil will be energized without any problem.

[0016]

FIG. 1 schematically shows the structure of an embodiment of the present invention. In this embodiment, a movable contact 2a of a key switch 2 is connected to a running energizing contact 2c and at the same time a timed operation is performed. And a discharge control means 11A connected in parallel to the timer capacitor of the time limit circuit to form a discharge circuit of the timer capacitor and a switch control means 11B for controlling the switch means. A reset circuit 11 is provided.

The switch control means 11B turns off the discharging switch means 11A when the operating energizing contact 2c of the key switch 2 is connected to the power supply, and disconnects the operating energizing contact 2c from the power supply. Then, the discharging switch means 11A is turned on. Other points are the same as those of the already proposed device shown in FIG.

FIG. 2 is a timing circuit 7 and a reset circuit 1 of FIG.
1 and the relay exciting switch 8 are shown in this embodiment. In this embodiment, the time circuit 7 includes diodes D1 and D3, resistors R2 and R3, a timer capacitor C1, and a zener diode Z1. Consists of
The reset circuit 11 includes a relay 12 having an exciting coil 12a to which the voltage of the battery 1 is applied through the energizing contact 2c during operation and a normally-closed contact 12b which is opened when the exciting coil is excited, and an anode to the ground side. It is composed of a diode D5 connected in parallel to the exciting coil 12a. The normally closed contact 12b of the relay is connected in parallel to both ends of the series circuit of the timer capacitor C1 and the resistor R3.
1 discharge circuit is configured. The relay excitation switch 8 has the same structure as the previously proposed device shown in FIG.

In the embodiment shown in FIG. 2, when the movable contact 2a of the key switch is brought into contact with the energizing contact 2c during operation, an exciting current flows from the battery 1 through the key switch to the exciting coil 12a of the relay 12 to cause the relay to turn on. The normally closed contact 12b opens. At the same time, battery 1 → key switch 2
→ diode D1 → resistor R2 → capacitor C1 → resistor R
3 → A current flows in the path of the battery 1 to start the timed operation of the timed circuit 7, and the pull coil 3a is energized. When charging of the timer capacitor C1 is completed and the timed operation is completed, the energization of the pull coil 3a is stopped.

Next, when the movable contact 2a of the key switch contacts the energizing contact 2d at the time of starting and a large starting current flows through the starter motor 4a, the terminal voltage of the battery 1 drops sharply. Here, the minimum value of the holding voltage of the relay 12 is selected to be a value (for example, about 2 V) which is sufficiently lower than the voltage of the battery 1 which is lowered due to the supply of the starting current to the starter motor 4a, and the exciting coil 12a of the relay is While the battery 1 is connected, the relay normally closed contact 12
b is kept open. Therefore, the electric charge of the timer capacitor C1 is not discharged through the normally closed contact 12b, and even if the voltage of the battery 1 is recovered and rises again, the timer capacitor C1 is not charged again. Therefore, in the state where the exciting coil 12a is connected to the battery, the timed operation will not be restarted even if the power supply voltage is reduced by the starter motor startup.
The energization time to the pull coil does not exceed the allowable range after the energization to the pull coil is restarted.

When the contact 2c for energization during operation is disconnected from the battery 1, the normally closed contact 12b of the relay 12 is closed to discharge the electric charge of the timer capacitor C1, so that the time circuit 7 is reset.

In the above embodiment, the reset circuit 11 is
The reset circuit 11 is composed of a relay having a normally closed contact 12b connected in parallel to the timer capacitor C1 and an exciting coil 12a that opens the normally closed contact when excited. , Semiconductor switches,
It can also be configured by a switch control circuit that controls the semiconductor switch. In FIG. 3, T1 is an NPN transistor which forms a discharge circuit for the timer capacitor C1 when a collector-emitter circuit is connected in parallel to the timer capacitor C1 and becomes conductive. This transistor T1 constitutes a reset semiconductor switch. Has been done.

C2 is a power supply capacitor for the reset circuit which is charged by the voltage of the battery 1 through the key switch 2 and the diode D6, and the base current is supplied to the transistor T1 through the resistor R4 by the electric charge accumulated in the capacitor C2. . In this example, the transistor T2
The diode D7 and the resistors R5 and R6 prevent the drive signal from being supplied to the reset semiconductor switch (transistor T1) when the running energizing contact 2c is connected to the power source, and the running energizing contact 2c. A reset switch control circuit is configured to permit supply of a drive signal to the reset semiconductor switch when the power is disconnected from the power supply.

In the embodiment shown in FIG. 3, when the movable contact 2a of the key switch is brought into contact with the energizing contact 2c during operation, the voltage of the battery 1 charges the capacitor C2 through the diode D6 and the diode D7 and the resistor R5. A base current is supplied to the transistor T2 through the transistor T2 to make the transistor conductive. Therefore, the base and emitter of the transistor T1 are short-circuited, and the transistor T1 is cut off. At the same time, the charging of the timer capacitor C1 is started by the voltage of the battery 1 and the timed operation is started. While the contact 2c for energization during operation is connected to the battery 1, the transistor T1 is kept in the cut-off state and the electric charge of the timer capacitor C1 is not discharged. Therefore, the time circuit 7 operates again for a time even if the starter motor is energized. Never do. The contact 2c for energizing during operation is the battery 1
When the transistor T2 is disconnected from the transistor T2, the transistor T2 is turned off, so that the base current is allowed to be supplied to the transistor T1 by the electric charge accumulated in the capacitor C2 and the transistor C2 is turned on. Therefore, the charge of the timer capacitor C1 is discharged through the transistor T1 and the time limit circuit 7
Is reset.

According to the reset circuit 11 of this embodiment,
Even when the voltage of the battery drops to a value lower than the minimum holding voltage of a normal electromagnetic relay when the starter motor starts, the discharge circuit is connected to the timer capacitor while the contact for energization during operation of the key switch is connected to the power supply. Can be separated from.

FIG. 4 shows another embodiment of the present invention. In this embodiment, the time limit circuit 7 is a timer capacitor C.
1 and comparator CM1, diode D8 and D9 and resistor R7
.About.R10 and a Zener diode Z1. The relay exciting switch 8 of the switch circuit 10 is composed of a transistor T3, a diode D4 and a resistor R11. The other points are similar to those of the embodiment shown in FIG.

In the circuit of FIG. 4, when the operating contact 2c of the key switch is connected to the battery 1, the normally closed contact 12b of the relay of the reset circuit 11 opens and the battery 1 → diode D8 → resistor R7 → diode. D9
→ Resistor R8 → Capacitor C1 → Battery 1 The charging current begins to flow in the capacitor C1 and the timed operation is started. The voltage Vc across the capacitor C1 is calculated by the comparator CM1.
The reference voltage Vr obtained by dividing the voltage between the anode side of the diode D9 and the ground by resistors R9 and R10 is input to the non-inverting input terminal of the comparator. While Vr> Vc, the output of the comparator CM1 is at a high level (the logic value is "1"), allowing the base current to be supplied to the transistor T3 through the resistor R11. Transistor T3 becomes conductive.
As a result, an exciting current flows through the exciting coil 9a of the relay 9 to close the contact 9b, so that the pull coil 3a is energized by the voltage of the battery 1. When the charging of the capacitor C1 progresses and its voltage Vc rises to Vr≤Vc, the timed operation ends and the output of the comparator CM1 becomes low level (state of logic value "0"). This causes the transistor T3
Since the base current is blocked from being supplied to the transistor, the transistor is turned off, and the energization of the exciting coil 9a of the relay 9 is stopped. As a result, the contact 9b of the relay 9 is opened, and the energization of the pull coil 3a is completed. While the contact 2c for energizing during operation is connected to the battery 1, the relay 12
Since the normally closed contact 12b is opened and the discharge circuit is separated from the capacitor C1, the electric charge of the capacitor C1 is not discharged and Vr> Vc again, and the energization of the pull coil 3a is not restarted. When the contact 2c for energization during operation is disconnected from the battery 1, the normally closed contact 12 of the relay 12 is
When b is closed, the time limit circuit 7 is reset.

[0028]

As described above, according to the present invention, the discharge circuit of the timer capacitor is configured to reset the time circuit when the contact for energization during operation of the key switch is disconnected from the power supply, and the energization during operation is performed. Since the reset circuit of the time limit circuit is configured to disconnect the discharge circuit from the timer capacitor and prevent the timer capacitor from discharging while the contact for power supply is connected to the power supply, the contact for energizing during operation is connected to the power supply. It is possible to prevent the timer capacitor from being discharged and recharged when the voltage of the power supply is lowered by the starter motor starting after the timed operation of the timed circuit.
Therefore, when the starter motor is started, it is possible to prevent the timed operation of the timed circuit from being performed again and restarting the energization of the pull coil of the fuel supply control solenoid, and it is possible to reliably prevent overheating and burning of the pull coil. There is an advantage that can be.

[Brief description of drawings]

FIG. 1 is a block diagram showing an overall configuration of an exemplary embodiment of the present invention.

FIG. 2 is a circuit diagram showing an embodiment in which each unit of FIG. 1 is made concrete.

FIG. 3 is a circuit diagram showing another embodiment in which each part of FIG. 1 is concretely shown.

FIG. 4 is a circuit diagram showing still another embodiment in which each part of FIG. 1 is specified.

FIG. 5 is a circuit diagram showing a proposed fuel supply control device for an internal combustion engine.

[Explanation of symbols]

1 battery 2 key switch 2a movable contact 2c Contact for energization during operation 2d Contact for energizing at starting 3 Solenoid for fuel supply control 3a pull coil 3b hold coil 4 Starter 5 Fuel injection pump 6 diesel engine 7 time circuit 10 switch circuit 11 Reset circuit 12 relays 12a Excitation coil 12b Normally closed contact C1 capacitor Power supply capacitor for C2 reset circuit T1 to T3 transistors F1 field effect transistor CM1 comparator

─────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-60-247032 (JP, A) Actually opened 5-36065 (JP, U) Actually opened 2-67080 (JP, U) Actually opened 61- 10947 (JP, U) (58) Fields surveyed (Int.Cl. ⁷ , DB name) F02D 41/06 330 F02M 37/00 311 F02N 11/08

Claims (4)

(57) [Claims] 1. A key switch having a contact for energization during operation, which is maintained in a state of being connected to a power source during operation of an internal combustion engine, and a contact for energization during startup, which is connected to a power source when the internal combustion engine is started, A fuel supply control solenoid having a pull coil excited to open the fuel supply valve when the engine is started and a hold coil excited to hold the valve open, and for energizing the key switch during operation A timer capacitor that is charged with a constant time constant by the output of the power supply when the contact is connected to the power supply, and a time-limit circuit that sets the operation time to the time during which the charging current flows in the timer capacitor; A pull coil energizing circuit for energizing the pull coil through a switch circuit that is closed only while the circuit is performing a timed operation, and operation of a key switch from the power source. Hold coil energizing circuit that energizes the hold coil of the solenoid through the energizing contact, and discharge of the timer capacitor is blocked while the energizing contact of the key switch is connected to the power source during operation of the key switch. And a reset circuit configured to configure the discharge circuit of the timer capacitor and reset the time limit circuit when the time current contact is disconnected from the power supply, and the operation time limit of the time limit circuit is equal to or less than the allowable rated power supply time of the pull coil. A fuel supply control device for an internal combustion engine, which is set. 2. The reset circuit comprises a discharging switch means connected in parallel to the timer capacitor so as to discharge the electric charge of the timer capacitor when the reset circuit is turned on; Switch control means for turning off the discharge switch means when connected, and for turning on the discharge switch means when the operating energizing contact is disconnected from the power supply; The fuel supply control device for an internal combustion engine according to claim 1. 3. The reset circuit comprises a relay having an exciting coil to which the voltage of the power source is applied through the contact for energization during operation and a normally closed contact which opens when the exciting coil is excited. 2. The fuel supply control device for an internal combustion engine according to claim 1, wherein a normally closed contact of the relay is connected in parallel to the timer capacitor so as to form a discharge circuit of the timer capacitor. 4. The reset circuit is connected in parallel to the timer capacitor and a reset circuit power supply capacitor that is charged by the output voltage of the power supply when the operating energizing contact is connected to the power supply. A reset semiconductor switch which is electrically connected by a drive signal given by an electric charge stored in the reset circuit power supply capacitor; and a drive to the reset semiconductor switch when the operating energizing contact is connected to a power supply. A reset switch control circuit that blocks the supply of a signal and permits the supply of a drive signal to the reset semiconductor switch when the contact for energization during operation is disconnected from the power supply. The fuel supply control device for an internal combustion engine according to claim 1.