JPS6253716B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a starting assist device for a diesel engine that is capable of highly efficient and reliable afterglow of a glow plug.

In general, starting assist devices for diesel engines perform so-called afterglow, which energizes the glow plug for a certain period of time even immediately after the engine starts, in order to improve the operating characteristics of the diesel engine immediately after starting. . For this reason, conventional devices are equipped with a resistor inserted in series with the glow plug or a relay for intermittently applying voltage to the glow plug. Either a lower heating current is applied to the glow plug, or a voltage is applied intermittently to the glow plug by means of this relay. However, in the case of the former configuration, a large installation space must be secured due to the heat generated by the current limiting resistor, and it is not possible to downsize the device.
It has the disadvantage that power is wasted in the resistor. On the other hand, in the latter configuration, which uses a relatively large current on and off, there is a problem with the durability of the relay, making it difficult to operate stably over a long period of time. The load on the relay changes widely, causing fluctuations in the power supply voltage, causing other electronic devices to malfunction, or causing discomfort as the brightness of the light changes as the relay turns on and off. It has its drawbacks.

SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide a starting aid for a diesel engine which eliminates the drawbacks of the prior art described above and which ensures optimum afterglow operation with a simple construction and without wasting power. There is a particular thing.

A feature of the present invention is that during afterglow operation, the generator is disconnected from the battery, and a voltage adjustment circuit switches the output voltage from the generator to a low voltage for afterglow, which is applied to the glow plug. Its purpose is to supply power to the circuit.

Hereinafter, the present invention will be explained in detail with reference to illustrated embodiments.

FIG. 1 shows an embodiment of a starting aid device according to the present invention. A starting aid, indicated schematically by the reference numeral 1, is connected to the power supply section of the diesel engine unit for the purpose of controlling the heating current supplied to the glow plug 2 provided in the cylinder head (not shown) of the diesel engine. . The power supply section of the diesel engine device includes an alternating current generator 3 driven by the engine, and stator coils L ₁ , L ₂ , L ₃ of the generator 3.
a rectifier circuit 4 that converts the AC output from the
A voltage adjustment circuit that adjusts the excitation current I _e of the rotor coil L ₄ of the generator 3 so that the battery 5 charged by the output from the rectifier circuit 4 and the output voltage V _put from the rectifier circuit 4 have a required value. It consists of 6.

The voltage adjustment circuit 6 includes a detection circuit 8 that detects the magnitude of the output voltage from the rectifier circuit 4 applied to the input line 7, and a reference voltage generation circuit 9 that generates a predetermined reference voltage _Vr . Detection voltage V from circuit 8
_d and the reference voltage V _r are compared in the comparison circuit 10 , and an error voltage _{V e} corresponding to the difference between these two voltages V _d and V _r is applied to the control circuit 11 . The control circuit 11 is provided between the output of the rectifier circuit 4 and the rotor coil _L4 , and changes the value of the excitation current _Ie according to the error voltage _Ve , thereby increasing the output voltage from the rectifier circuit 4. Voltage adjustment is performed so that the value of V _put becomes the required value. This voltage adjustment circuit 6 further includes a detection voltage conversion circuit 12, and when the switch S ₁ is closed, the switch S ₁
The configuration is such that the value of the detection voltage V _d from the detection circuit 8 can be increased by a predetermined ratio compared to the case where the output voltage V _put is in an open state, and the adjusted voltage value of the output voltage V put can be decreased.

One end of the glow plug 2 is grounded, and the other end is connected to the positive terminal of the battery 5 via a sensing resistor 13 and a switch 14, and the connection point between the sensing resistor 13 and the switch 14 is connected to the positive terminal of the battery 5 via a switch _S2 . It is connected to a low voltage line 15 connected between changeover switches S ₃ and S ₄ , and a heating current is supplied to the glow plug 2 via either switch 14 or S ₂ . By passing the same current as the current flowing through the glow plug 2, the sensing resistor 13 generates a temperature voltage V at both ends thereof at a level corresponding to the temperature of the glow plug 2.
_h , and the temperature voltage V _h is an operating signal indicating that the key switch 16 is turned on.
_K1 and the starting signal _K2 are input to the rapid preheating control circuit 17.

The rapid preheating control circuit 17 outputs a control signal C1 to turn on the switch 14 in response to the key switch ₁₆ being closed and the level of the operation signal K1 becoming " ₁ ", thereby turning on the glow plug. 2
Once the upper limit of the predetermined rapid preheating temperature range T ₁ ~ T ₂
Heated to _T2 . At this time, the switch 14 is turned off unless the starting signal _K2 is "1". On the other hand, if the starting signal _K2 is "1", the control signal
The switch 14 is controlled on and off by _C1 to maintain the temperature of the glow plug 2 within the above-mentioned rapid preheating temperature range. The switch 14 is configured to open the switch 14 when the control signal C1 is "0" and close the switch 14 when the control signal _C1 is "1".
The temperature control operation described above is performed based on the temperature voltage V _h indicating the glow plug temperature T. Therefore, as shown in FIG. 2, when the operating signal _K1 reaches the "1" level at time t= _t1 , the level of the control signal _C1 also temporarily becomes "1", and the switch 14 is closed and the battery is discharged. A rapid heating current is supplied from 5 to the glow plug 2, and the temperature T of the glow plug 2 begins to rise (FIG. 2 a, c, e). Once the temperature T of glow plug 2 reaches the upper limit of the rapid preheating temperature range
After reaching T ₂ , the switch 14 remains open and preheating of the glow plug 2 is stopped until the starting operation is started. When the starting operation is started at time _t2 and the level of the starting signal _K2 becomes "1", the level of the control signal _C1 is controlled by the temperature voltage _Vh , and the switch 14 is repeatedly turned on and off to plug the glow plug. After the temperature of the control signal K2 is maintained within a predetermined temperature range and the level of the starting signal _K2 changes from "0" to "1", the level of the control signal _C1 changes to "0" at the timing when it becomes "0" again. The switch 14 remains open. As will be described in detail later, when the above-mentioned rapid preheating operation is performed, the switches S ₁ to S ₄ are in the state shown by the solid lines in FIG. 1.

The potential of the neutral point of the stator coil of the generator 3 is applied to the afterglow control circuit 18 via line LN, and a predetermined voltage is output to this neutral point when the engine is successfully started. is input to the afterglow control circuit 18, so that the afterglow control circuit 18 becomes operable. Under the above conditions, the afterglow circuit 18 changes the starting signal _K2 from "1" to "0".
In response to the change in the level, it becomes "1" level,
It outputs an afterglow control signal C ₂ (see FIG. 2 d) which is maintained at the "1" level for a predetermined period ta determined according to the water temperature signal K ₃ indicating the temperature of the cooling water of the engine. Afterglow control signal
C ₂ is a relay 19 that operates switches S ₁ to S ₄ .
When the level of the afterglow control signal C ₂ is "0", the relay 19 is deenergized and opens the switches S ₁ and S ₂ , and also switches the switches S ₃ and S ₄ to the switching state shown by the solid line. shall be. On the other hand, when the level of afterglow control signal _C2 becomes "1",
Relay 19 is energized to close switches S ₁ and S ₂ and to switch S ₃ and S ₄ to the switching state shown by dotted lines. The switches S ₃ and S ₄ are switching means for selecting one of two connection states: a state in which the output voltage V _put is applied to the load 20 other than the battery 5 and the glow plug 2, and a state in which it is not applied. When the relay 19 is in the de-energized state, the output voltage _Vput is applied to the battery 5 and the load 20,
On the other hand, when the relay 19 is in the energized state, the output voltage V _put is applied to the input line 7 via the low voltage line 15 without being applied to the battery 5 and the load 20 .

According to this configuration, before the key switch 16 is turned on, the relay 19 is in a de-energized state, so that the switches _S1 to _S4 are all in the state shown by solid lines in FIG. Therefore, when the key switch 16 is closed at t= _t1 , the switch 14 is closed and the glow plug 2 is in a rapid preheating state where the voltage of the battery 5 is applied via the switch 14, and the rapid preheating control circuit is activated. 17, the glow plug 2 is rapidly heated to the required preheating temperature. In this case, since the switch S ₁ is in the open state, the voltage regulating circuit 6 controls the output voltage of the generator 3 so that an output voltage _Vput having substantially the same value as the battery 5 is obtained. When the starting signal _K2 becomes "1" at t= _t2 , the temperature is controlled within the desired temperature range during the starting period, and when the starting operation is completed at t= _t3 , the engine has successfully started. For example, the level of the starting signal _K2 is "1" at t= _t3 .
In response to the change from 0 to 0, the level of afterglow control signal C ₂ becomes 1, and at the same time as switches S ₁ and S ₂ are closed, switches S ₃ and S _{4 are} closed.
is switched as shown by the dotted line in the figure, and the afterglow operation is started. At this time (t=t ₃ ), the level of the control signal C ₁ becomes "0" forcibly, so that the switch 14 becomes open. As a result, the battery 5 and the load 20 are disconnected from the generator circuit, and the glow plug ₂ is supplied with power from the generator circuit via the switch S2. At this time, as a result of the switch _S1 in the voltage adjustment circuit 6 being closed, the value of the output voltage _Vput is such that the value of the output voltage Vput is such that the heating energy necessary for the afterglow operation is given to the glow plug at the same time as the afterglow operation starts. The voltage is adjusted to a predetermined value lower than the voltage of the battery 5. Therefore, during the period ta during which the level of the afterglow control signal _C2 is "1", the afterglow operation can be performed on the glow plug 2 without using a resistor, a relay, or the like. This eliminates the disadvantages of requiring a large resistor that requires a large space and wasting power during afterglow operation, and also eliminates the disadvantages of intermittently opening and closing the relay contacts to generate large currents. Since there is no need to perform a chopper operation, it is possible to perform an extremely reliable and efficient afterglow operation.

While the above-mentioned afterglow operation is being performed, loads other than the glow plug are operated by the battery 5, but since it is only for a short time, there is no problem at all. After the period ta set by the afterglow control circuit 18 has elapsed, the relay 19 is deenergized, the battery 5 and the load 20 are connected to the generator circuit, and the value of the output voltage from the generator circuit also returns to its original value. will be returned to.

In addition, when applying the starting aid device of the present invention, a charging circuit with a configuration different from that of conventional charging circuits is required, but since a current limiting resistor or relay is not required, it is advantageous from a comprehensive and long-term perspective. This will ultimately lead to lower costs.

Instead of the voltage regulation circuit used in the above embodiment,
You can use a mechanical regulator or
In addition, when using an electronic regulator as in the embodiment, the reference voltage V from the reference voltage generation circuit 9
It may be configured such that _r changes in response to turning on and off of the switch _S1 , and the detection voltage conversion circuit 12 is removed.

Furthermore, in the embodiment, the glow plug is heated at a predetermined constant low voltage during afterglow operation, but the temperature of the glow plug during afterglow is detected and this detected temperature is set to a predetermined constant value. Alternatively, the reference voltage V _r may be changed in accordance with the glow plug temperature, and the voltage applied from the power generation circuit to the glow plug may be adjusted to keep the glow plug temperature constant.

According to the present invention, as described above, there is no need for large resistors or chopping relays, etc., and the starting assist part can be systematically connected to the charging system, resulting in cost reduction and a simple configuration. This provides excellent effects such as being able to perform the afterglow operation reliably without wasting power.

[Brief explanation of the drawing]

Fig. 1 is a circuit diagram of an embodiment of the present invention, Fig. 2a
FIGS. 2e to 2e are waveform diagrams of various parts for explaining the operation of the apparatus shown in FIG. 1. 1...Starting aid device, 2...Glow plug, 3
... Generator, 5 ... Battery, 6 ... Voltage adjustment circuit, 12 ... Detection voltage conversion circuit, 14 ... Switch, 18 ... Afterglow control circuit, 19 ...
Relay, S ₁ ~ _{S 4} ... switch.

Claims (1)

[Claims] 1. A power supply unit that receives power from a power supply unit that includes a power generation unit whose output voltage is adjusted by a voltage regulator and a battery that is charged by the output voltage from the power generation unit and supplies power to the load. A starting aid for a diesel engine that performs an afterglow operation after a rapid preheating operation of a plug includes a control circuit that sets the timing of the afterglow operation, and a load other than the glow plug during the afterglow operation period set in the control circuit. a switch means for electrically disconnecting the output voltage from the power generating section together with the battery; and adjusting the voltage regulator so that the value of the output voltage is changed to a low voltage level for the afterglow during the afterglow operation period. 1. A starting assist device for a diesel engine, characterized by comprising means.