JPS5874874A - Controlling appartaus for glow plug - Google Patents

Abstract

PURPOSE:To save electric power, by changing the voltage impressed on glow plugs at the time of preheating from that impressed at the time of after-glow by using the output voltage of an alternator before the rectification of the same. CONSTITUTION:In a three-cylinder or six-cylinder diesel engine, output current of a three-phass alternator 5 before rectification of the same is applied from each terminal of the three stator coils to glow plugs 2a-2c for the purpose of after- glow via a circuit independent from a preheating circuit. In case of three- cylinder engine, current is supplied from one terminal to one glow plug respectively. In case of six-cylinder engine, on the other hand, current is supplied from one terminal to two glow plugs respectively. With such an arrangement, a voltage of a level equal to 1/2 of the level of the mean voltage required at the time of preheating is impressed at the time of after-glow, so that the electric power can be saved.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a so-called afterglow system in which a glow plug is energized for the purpose of reducing noise during rotation or low rotation and reducing HC components of exhaust gas.

It is well known that in a diesel engine, when the glow plug is energized after the engine is started, especially when the engine is cold, it is effective in reducing noise, especially idling noise, and reducing HC in exhaust gas.

In this case, it is not necessary to supply the same power to the glow plug as before starting. On the other hand, if the battery voltage is supplied as is for a long period of time, the power consumption will be excessive and the plug will burn out, making it impractical. Therefore, in the past, after starting, the battery voltage was lowered by a resistor, which had the disadvantage that power consumption in the resistor was wasted.

This invention provides a three-cylinder or six-cylinder diesel engine with three circuits for afterglow in addition to the preheating circuit.
The unrectified current from each terminal of the three-phase stator coil of the alternator is transferred from one terminal to one glow plug (in the case of a three-cylinder engine) or from one terminal to one glow plug (in the case of a six-cylinder engine). ) A circuit is installed to supply electricity from one terminal to two glow plugs) During preheating, the voltage of the storage battery is directly applied to the glow plugs and the electricity flows, but during afterglow, a pulsating current flows through the glow plugs. At this time, by taking advantage of the fact that the average voltage applied to the glow plug is approximately 172 times the average voltage during preheating,
It is an object of the present invention to provide a glow plug control device that can omit a resistor in a conventional device, thereby saving power consumed by the resistor and eliminating waste of power.

FIG. 1 shows a first embodiment of the invention.

In this figure, 28 to 2C are glow plugs for preheating installed in each cylinder of a three-cylinder diesel engine. Alternator 5 receives rotational driving force from the output shaft of the engine, generates three-phase alternating current in stator coils 5a to 5C, and supplies charging current to battery 3 via rectifier diodes 4a to 4f. The energizing wires to the glow plugs 2a to 2C are a line from the battery 3 via the contacts of the first relay 8 and the contacts of the second relay +9, and a line from the pre-rectified terminal of each stator coil 5a to 5C of the alternator 5 to the second relay. A line passing through the contacts of the relay 9 is provided.

The first relay 8 is then deenergized by the transistor 12 by the preheating control circuit IO. Moreover, the second relay 9 is
The afterglow control circuit 11 causes the transistor 13 to
is extinguished by.

The second relay 9 has three independent relay circuits inside, and the contacts 9b, 9d, and 9f are connected to the first relay 8 in a non-contact manner. Contact points 9a, r9c and 9e are connected to terminals of each stator coil 5a to 5c of alternator 5 before rectification, respectively. The glow plugs 2a to 2c have contacts 9b and 9 when the second relay 9 is not energized.
d, connected to 9f.

The preheating control circuit 10 and the afterglow control circuit 11 are activated by being supplied with power from the battery 3 when the engine key switch 1 is turned on. The preheat control circuit 10 is comprised of an engine start detector 14 and a switch circuit 15 responsive to its output. The afterglow control circuit 11 also includes a water temperature detection circuit 116 consisting of a thermistor and a voltage comparison circuit 17 so as to drive the second relay 9 depending on the engine temperature. - In the above configuration, first, when the key switch l is closed to start the engine, the first relay 8 is energized and a relatively large current is supplied from the blower plug 3 to the blow plugs 2a to 2C. The glow plugs 2a to 2C are heated rapidly.

Thereafter, when the starter switch is closed to start the starter and the engine starts rotating, the start detector 14 in the preheating control circuit 10 detects the start, and in response to its input, the switch circuit 15 gives a low level signal to the transistor 12. The first relay 8 is deenergized and the glow plug 2 is transferred from the battery 3 to the glow plug 2.
Power supply to a to 2d is stopped. The afterglow control circuit 11 can substantially operate when the first relay 8 is de-energized, controls the energization of the second relay 9, and determines its energization period.

That is, the water temperature detector 16 is attached to the cooling water jacket of the engine and generates a DC voltage whose value corresponds to the cooling water temperature, and this DC voltage is compared with a threshold level in the voltage comparison circuit 17.

The threshold shield level is set to correspond to, for example, 40° C., and an output signal is applied to the transistor 1.4 which becomes a low level when it is lower than this level and a high level when it is higher than this level. Therefore, after starting the engine, the glow plugs 2a to 2 are connected to the terminals of the stator coils 5a to 5C of the alternator 5 before rectification via the second relay 9 until the engine cooling water temperature reaches 40°C.
2C is energized.

FIG. 2 shows a second embodiment of the invention. This diagram is
In the embodiment of a 6-cylinder diesel engine, the differences in configuration from FIG. . That is, the glow plugs are attached to each cylinder, and the six glow plugs 2a to 2f are divided into three groups of two glow plugs and energized. The second relay 18 is closed when the relay is not energized, and when energized, connects each terminal of the stator coils 5a to 5C of the alternator 5 before rectification to the glow plugs 2a to 2f.

The difference in operation from the first embodiment is that the six glow plugs attached to each six-cylinder engine are energized in three groups, two of each, and the second relay is single-throw. Relay 18 and current limiting diode 19aN1
9c was added. During preheating, electricity is applied to the glow plug through the diodes 19a to 19C. On the other hand, during afterglow, when the afterglow control circuit 11 outputs a high-level signal to the transistor 13, the die 2 relay 18 is energized, and the terminals of the stator coils 5a to 5c of the alternator 5 are connected to each other before rectification. The glow plugs 2a to 2c are energized. In this case, no current flows into the preheating circuit due to the action of the diodes 198 to 19c.

In the first and second embodiments described above, the cooling water temperature was detected and used as the afterglow control parameter. An equivalent drop can be obtained by measuring. Further, the thermistor and voltage comparison circuit may be replaced with a contact type thermostat.

Furthermore, as the afterglow 111m parameters, the engine speed, the amount of depression of the accelerator pedal, the traveling speed line of the vehicle, the noise in the engine room, and the vibration of the WA valve may be detected to determine whether or not to energize.

Alternatively, the battery voltage and the value of the additional current flowing out from the battery may be detected and used as parameters. Furthermore, a timer may be used to turn on the power only for a certain period of time.

In the embodiments described above, appropriate hysteresis can be set in the voltage comparator circuit 17 by a known method to prevent chattering.

Furthermore, the presence or absence of energization may be determined by combining two or more of the illustrated parameters and using a logical sum condition or a logical product condition.

In addition, in the 1-, as in FIG. 3, the second relay 18
and current limiting diodes 192 to 19c to the second relay 9.
may be used instead of , and vice versa in FIG.

As described above, the present invention specifies the pre-rectified output of the alternator to control the voltage applied to the glow plug.
It is possible to substantially change the time between preheating and after-heating, and as a result, there is an excellent effect of eliminating the need for a voltage drop resistor and eliminating wasted power.

[Brief explanation of drawings]

FIGS. 1 and 2 show the first embodiment of the present invention. FIG. 7 is an electrical wiring diagram showing a second embodiment. 1...Engine key switch +2a~2f...Glow plug, 3...Battery t4a~4f...G1 diode, 5...Alternator, 8...First relay, 10...Preheating Control circuit, 11... Afterglow control circuit. 14...Start detector, 16...Water temperature detector. Representative Patent Attorney Takashi Okabe Continued from page 1 0 Author: Sonai Kuwamon 0 Author: Tomio Kumoi, 1-1 Showa-cho, Kariya City, Nippondenso Co., Ltd. Applicant: Nippondenso Co., Ltd., Showa-cho, Kariya City 1-chome 1

Claims (1)

[Claims] A glow plug installed in a diesel engine having a number of cylinders that is a multiple of 3 receives current from each of the three terminals of the stator coil of a three-phase alternator driven by the engine before commutation to each glow plug divided into three parts. , a switch means for opening and closing the energization circuit, and a control means for controlling the switch means to control the energization time of the glow plug in the energization circuit. Glow plug control device.