JPS6218690Y2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a preheating circuit for a diesel engine.

A conventional preheating circuit using an electric heater is configured as shown in Fig. 1. When starting the engine, first turn on the preheating switch SW2, then turn on the key switch SW1 to the contact R1, and then the relay 2 turns on. from battery 1 to ribbon heater 3.
and the heater signal 4 is energized. The ribbon heater 3 generates heat and heats the intake air in the manifold, and the heater signal 4 starts to become red hot.
Based on the red-hot state of the heater signal 4, the operator switches the key switch 1 to the start position R2 and starts the engine.

By the way, in order to operate the engine well in a place where the atmospheric temperature is low, such as at a high altitude, it is necessary to perform a so-called warm-up operation in which the intake air is continued to be heated.
However, since ribbon heaters generally have a large capacity, the battery consumes a large amount of power, and care must be taken because the battery will become flat if warmed up for a long time.

When warming up using a conventional preheating circuit, the operator has to turn on the key switch and preheating switch each time to supply electricity from the battery to the electric heater, which is extremely difficult to operate and makes warming up extremely difficult. It is. Moreover, if you forget to turn off the switch, the battery pack will become flat.

The present invention was developed with the aim of eliminating the above-mentioned drawbacks of the conventional technology.It is equipped with a generator for warm-up operation in addition to the one for charging the battery, and when the engine is started, the electric heater is automatically disconnected from the battery. The present invention provides a preheating circuit for a diesel engine that performs warm-up operation by applying the generated voltage of the generator to an electric heater.

Hereinafter, the present invention will be described in detail based on one embodiment of the accompanying drawings.

In FIG. 2, the terminal 3a of the ribbon heater 3 is connected to the battery 1 via the normally open contact 2a of the relay 2, and the other terminal 3b is grounded.
One end of relay coil 2b is preheating switch SW2
The other end is connected to the contact point S _{b of} , and the other end is grounded via a cutoff circuit, for example, a hydraulic switch SW3. The oil pressure switch SW3 is configured to be turned on when the engine is stopped and the engine oil pressure is low, and turned off when the engine starts and enters normal operation and the engine oil pressure rises to a predetermined pressure. A contact S _a of the preheating switch SW2 is connected to a contact ACC of the key switch SW1.

One end of the bimetal switch 11 of the detection circuit 10 is connected to the relay contact 2a via the current limiting resistor R _a .
and the ribbon heater 3, and the other end is connected to the intermediate terminal 3c of the ribbon heater 3. Further, a display device such as a display lamp 12 is connected in parallel to the resistor R _a . This bimetal switch 1
1 is designed to be switched off when a predetermined current flows for a predetermined time. Note that one end of this bimetal timer 11 is connected to the intermediate terminal 3c of the ribbon heater 3 as described above, and therefore, the voltage applied to the bimetal timer 11 is the same as when the heater voltage (battery voltage) is 24V. For 12V
It will be used as. Furthermore, by adjusting the current flowing through the bimetal timer 11 using the resistor R _a , the operating time of the bimetal timer 11 , that is, the time t from the switch-on state to the switch-off state can be set to a desired value. This time t is set to a predetermined time corresponding to the preheating time of the ribbon heater 3, depending on the capacity of the ribbon heater 3 to be used. In this way, the detection circuit 10 that detects heater disconnection and preheating completion is configured.

The contact 20a of the relay 20 is connected to the wire, and the contact 20b is connected to the wire.
is connected to the output terminal 30a of the generator 30 via a current limiting resistor _Rb . Further, one end of the relay coil 20c is grounded to the contact 20a, and the other end is grounded via an engine coolant temperature sensor, for example, a temperature switch 40. The generator 30 is dedicated to preheating the heater 3 during warm-up operation, and is driven by the engine. Further, the temperature switch 40 is configured to be turned on when the engine cooling water temperature is below a predetermined temperature, and turned off when the temperature exceeds a predetermined temperature.

The voltage setting device 25 controls the heater 3 during warm-up operation.
It is placed on the panel of the driver's cab and can be set to the desired voltage. The control circuit 26 is for controlling the generated voltage of the generator 30 during warm-up operation, and the set voltage of the setting device 25 is input to the input terminal 25a, and the key switch SW is input to the input terminal 26b.
1. Battery voltage is applied via preheating switch SW2. The device enters the operating state when the battery voltage is applied to the input terminal 26b. The voltage applied to the heater 3 is fed back to the input terminal 26c. In addition, the output terminals 26d and 26e are connected to the generator 30.
are connected to field coil terminals 30b and 30c. Then, the current applied to the field coil (not shown) of the generator 30 is controlled according to the deviation between the set voltage Vc of the setting device 25 and the current applied voltage of the heater 3, and the output voltage of the generator 30 is controlled. I'm starting to do that. Therefore, the operator can set the heat generation temperature of the heater 3 to a desired temperature by setting the set voltage Vc to an appropriate value depending on the outside temperature.

Now, when starting the engine, turn on the preheating switch.
Turn on SW2 and turn key switch SW1 to ON position
When the ACC is turned on, the relay coil 2b is energized and the contact 2a is turned on. And Batsuteri 1
The ribbon heater 3 and the detection circuit 10 are energized, the ribbon heater 3 generates heat and heats the intake air in the intake manifold, and the indicator lamp 12 lights up. At the same time, the relay 20 is energized and turned on,
Connect the output terminal 30a of the generator 30 to the line.
If there is an abnormality in the ribbon heater 3, for example, if the wire is disconnected, no current will flow to the detection circuit 10.
Lamp 12 does not light up. Therefore, the operator can immediately sense any abnormality in the ribbon heater 3. Further, the contact ACC of the key switch SW1 does not need to be held, and the operator only needs to look at the lamp 12 after turning on the key switch SW1.

When the predetermined preheating time t has elapsed, the bimetal timer 11 is switched off and the indicator lamp 12 is turned off. At this time, the intake air in the manifold is sufficiently preheated. The operator turns the key switch SW when this indicator lamp 12 goes out.
1 to the start position R2 and start the engine. When the engine starts, engine oil pressure increases accordingly. When the engine enters a normal operating state and the engine oil pressure reaches a predetermined level, the hydraulic switch SW3 is turned off, the relay coil 2b is deenergized, the contact 2a is turned off, and the heater 3 is completely disconnected from the battery 1.

On the other hand, when the engine starts, the generator 30 is driven and the generated voltage is applied to the ribbon heater 3. The ribbon heater 3 generates heat according to the generated voltage of the generator 30, heats the intake air, and maintains the warm-up operation state. When the engine warms up and the engine cooling water temperature exceeds the specified temperature, the temperature switch 4
0 is turned off, relay 20 is deenergized, and contact 2
0a and 20b are turned off. Therefore, the ribbon heater 3 is disconnected from the generator 30, and the warm-up operation is canceled.

After the warm-up operation is canceled, the engine cools down due to the intake air and the engine cooling water temperature drops below the specified temperature.
Temperature switch 40 is turned on and relay 20 is energized. Therefore, the ribbon heater 3 is connected to the generator 30 again, and warm-up operation is started. In this way, the energization to the ribbon heater 3 is controlled on and off according to changes in the engine cooling water temperature, thereby performing a warm-up operation. The indicator lamp 12 indicates that the relay 20 is on,
Turns on and off depending on the off status. Therefore, the operator can sense from this lamp 12 that the warm-up operation is in progress.

FIG. 3 is a diagram showing another embodiment of the present invention, in which a fixed resistor is used in place of the voltage setting device 25 and control circuit 26 shown in FIG. 2. generator 3
0 coil terminal 30b is connected to the contact S of the preheating switch _SW2 via the excitation current limiting fixed resistor Rc.
_b , the terminal 30c is grounded, and a predetermined excitation current is applied from the battery 1 to the field coil of the generator 30. After the engine is started, the generator 30 outputs a predetermined voltage according to the excitation current and applies it to the ribbon heater 3 . The ribbon heater 3 generates heat according to this applied voltage and heats the intake air. In this way, warm-up operation is performed.

As explained above, according to the present invention, it is possible to continue heating the intake air without worrying about battery consumption, and there is no need to worry about oxygen depletion. The intake air can be heated over a period of time, and the white smoke emission time can be shortened. Particularly in the future, as the compression of diesel engines continues to become lower due to issues such as exhaust gas regulations, heaters that do not consume oxygen will be extremely effective and have excellent effects such as eliminating problems such as oxygen deficiency at high altitudes.

[Brief explanation of the drawing]

FIG. 1 is a diagram of a conventional diesel engine preheating circuit, FIG. 2 is a diagram showing one embodiment of the diesel engine preheating circuit according to the present invention, and FIG. 3 is another embodiment of the diesel engine preheating circuit of the present invention. It is a figure which shows an example. DESCRIPTION OF SYMBOLS 1... Battery, 2, 20... Relay, 3... Ribbon heater, 10... Detection circuit, 11... Bimetal timer, 25... Voltage setting device, 26... Control circuit, 30
...generator, 40...temperature switch, SW1...key switch, SW2...preheating switch, SW3...hydraulic switch.

Claims (1)

[Scope of Claim for Utility Model Registration] (1) In a diesel engine preheating circuit that preheats intake air by energizing a heater placed in the intake manifold, a battery and a generator for charging the battery are provided separately. , a warm-up generator that generates a predetermined voltage when the engine is started; and a connection that connects the battery and the heater when a key switch is turned on, and also connects the warm-up generator and the heater. holding means for separating the battery from the heater when the engine is started and maintaining connection between the warm-up generator and the heater; A preheating circuit for a diesel engine, comprising: control means for controlling a voltage at a predetermined value to a predetermined value; and release means for releasing the connection between the warm-up generator and the heater upon completion of preheating. (2) The holding means includes means for detecting that the engine oil pressure has exceeded a predetermined value, and means for separating the battery from the heater based on the detection output of this detecting means. A preheating circuit for a diesel engine according to item 1. (3) The preheating circuit for a diesel engine according to claim 1, wherein the control means is a resistor that limits the excitation current of the generator for warm-up operation. (4) The control means includes means for setting the voltage applied to the heater, means for determining a deviation between the set voltage and the voltage generated by the generator for warm-up operation, and a control means for controlling the power generation for warm-up operation based on this deviation. A preheating circuit for a diesel engine according to claim 1, further comprising means for controlling an excitation current of the engine. (5) The release means includes a means for detecting that the temperature of the engine cooling water has reached a predetermined temperature or higher, and a means for releasing the connection between the warm-up generator and the heater based on the detected output of the detecting means. A preheating circuit for a diesel engine according to claim 1, comprising: