JPH036872Y2 - - Google Patents

Description

[Detailed description of the invention] <Industrial application field> The present invention relates to an energization control device for glow plugs installed in the combustion chamber or intake passage of an engine, such as glow plugs for diesel engines, and particularly for so-called key-in-glow type glow plugs. This invention relates to a glow plug energization control device.

<Prior Art> As seen in Japanese Patent Laid-Open No. 54-95846 and Japanese Patent Laid-open No. 55-69760, for example, a glow plug energization control device for a diesel engine as shown in FIG. 8 is known. This is an energization control method generally called key-in-glow.

That is, the power supply 1 is input to the control means 4 through the terminal _a1 of the control device 3 via the manual ignition switch 2, but in the key-in-glow method,
Key in parallel to ignition switch 2
A switch 10 is provided, and the key-in switch 10 is provided.
When the switch 10 is turned on, the key-in timer circuit 5 is operated to control when the control means 4 outputs the operation start signal _S1 . When the operating circuit signal S1 is input from the key-in timer circuit 5, the control means 4 turns on the relay switch 8 for a predetermined time _tT1 , and the glow plug 7 is heated by electricity without waiting for the ignition switch 2 to be operated.

Note that the key-in switch 10 includes the ignition switch 2, the start switch 11,
This switch means is turned on when the engine key is inserted into a switch device equipped with an accessory switch or the like.

The diode 6 is configured such that when current is supplied from the key-in timer circuit 5 to the control means 4,
This prevents reverse current from flowing through the line from terminal _A1 to ignition switch 2 to other vehicle electrical components. A glow lamp 9 indicates that the ignition switch 2 is turned on and the glow plug 7 is heated by electricity.

The operating time (glow plug energization heating time) _tT1 of the control means 4 depends on the driving state of the vehicle, and for example, the start switch 11 is turned on while the starter motor (not shown) is cranking.
A neutral switch 12 that detects that the gear shift position of a transmission (also not shown) is in the neutral position, a vehicle speed sensor 13 that detects vehicle speed, and a rotation sensor 1 that detects engine rotation speed.
4. Temperature sensor 15 that detects engine cooling water temperature
The output signal from the glow plug 7, the terminal voltage of the glow plug 7, etc. are input to the control means 4 via the terminals _b1 to _b6 , respectively, and the operating time _tT1 is determined according to these operating conditions. In this case, if the control means 4 is constituted by a control unit such as a microcomputer, the above operating time t _T1 is calculated and depends on, for example, the glow plug terminal voltage (terminal b ₆ ), the cooling water temperature (terminal b ₅ ), etc. The engine is preheated for the operating time t _T1 before starting. After the engine is started, in addition to the above, the glow plug 7 is energized by controlling the neutral position of the transmission (terminal b ₂ ), vehicle speed (terminal b ₃ ), engine speed (terminal b ₄ ), etc. Of course, the energization control after starting can be omitted, the operating time t _T1 can be made constant, and the control means 4 can of course be configured as a hard circuit.

<Problems to be solved by the invention> In the case of such a key-in-glow type glow plug energization control device, the glow plug is energized the moment the engine key is inserted into the switch device. This has the advantage that the time it takes to turn on the ignition switch 2 can be saved, and the time it takes to start the engine can be shortened. However, for example, when the engine key is inserted into the switch device, the power terminals c ₁ and c ₂ are disconnected for battery replacement or maintenance, and then they are connected again (c ₁ , c ₂ ). Since there is no such safety device, the following inconveniences are likely to occur as shown in FIG.

That is, when the power supply terminal is connected, the key-in switch 10 is closed and the power supply current is input to the key-in timer circuit 5, so the control means 4 is started to operate and the relay switch 8 is turned on. Then, the glow plug 7 is energized. Therefore, when connecting power terminals c ₁ and c ₂ , a large instantaneous current flows through the connection, which can generate large sparks that can damage the power terminals and cable terminals, or cause the worker to become surprised and take his or her hands elsewhere. This can easily lead to unexpected secondary disasters such as hitting the product or dropping a tool, causing a major shock to the electrical circuit.

In view of these inconveniences, the applicant first filed a patent application in 1983.
−A patent application related to No. 198643 was filed, and the key in
We proposed a safety measure that does not energize the glow plug for a predetermined period of time even if the power terminal is connected or disconnected while the switch is on.

In response to this, the present invention aims to provide a similar safety measure that reduces the number of relay switches used, can be configured only with electronic circuits, and is superior in terms of reliability, compactness, and cost.

<Means for Solving the Problems> To this end, the present invention includes a delay means for delaying and outputting the rise of the power supply voltage signal by a predetermined time (t ₁ ), and a delay means configured independently of the above-mentioned switch. A predetermined period of time (t ₂
> _t1 ) Pulse generating means for generating a pulse, and glow energizing means for supplying power supply current to the glow plug for a predetermined period of time when two high-level output conditions of the pulse generating means of the delay means are satisfied.

<Function> As a result, the delay time of the delay means elapses, the power supply voltage rises sufficiently, that is, the power supply terminal connection state becomes stable, and at the same time, the glow energization means continues for a predetermined time only when the switch means (key-in switch) is closed. is activated and controls the energization of the glow plug. Therefore, if the power supply terminal is connected while the switch means is in the on state, the pulse generating means generates a pulse triggered by the energization of the switch means during the delay time of the delay means, and the AND condition is not satisfied, and the glow plug is no longer energized. On the other hand, when the power supply voltage is stable, the output of the delay means becomes high level, so if you remove the engine key from the switch means and reinsert it again, you can generate a pulse signal.
It is possible to carry out the usual key-in-glow type glow plug energization control. These delay means, pulse generation means, and glow energization means can be constructed using only electronic circuits, except for the use of a relay switch in the direct energization driving circuit of the glow plug.

<Examples> Examples of the present invention will be described below based on the drawings.

The first embodiment includes a control device 23 shown in FIG. 2 that includes a key-in timer circuit 25 shown in FIG.
is replaced with the control device 3 of the glow plug energization control device shown in FIG.
Elements similar to those in the figures are given the same reference numerals. The input signal to the key-in timer circuit 25 is the energization signal (terminal) of the key-in switch 10.
In addition to a ₂ ), the voltage of the power supply 1 led through the coil of the relay switch 8 is input through the terminal a ₄ .

In Figure 1, when power terminals c ₁ and c ₂ are removed and reconnected with the engine key inserted into the switch device (key-in switch 10 closed), the power supply voltage V _B from terminal a ₄ is delayed. It is input to means A.

The delay means A consists of a time constant circuit 31 composed of resistors _R1 to _R3 , a capacitor _C1 , and a Zener diode _ZD1 , and as shown in FIG. 3a, V _B
is output to the AND gate 32 as a voltage signal _V1 with a slow rise.

On the other hand, when the power supply terminals c ₁ and c ₂ are connected, a power supply current flows through the closed key-in switch 10, and the voltage signal V ₂ is inputted to the pulse generating means B from the terminal a ₂ .

Pulse generating means B includes a resistor R ₄ , a capacitor C ₂ ,
A smoothing circuit 33 using a Zener diode ZD ₂ ,
A time constant circuit 34 including a resistor R ₅ and a capacitor C ₃ ;
It consists of a monostable multivibrator 35. The voltage signal V ₂ is smoothed by a smoothing circuit 33, and the power supply voltage of the monostable multivibrator 35 is
The voltage signal V ₂ ' is supplied as V 2 ', and a voltage signal V ₃ whose rise is slightly delayed with respect to the voltage signal V ₂ ' is generated by the time constant circuit 34 to trigger the operation of the monostable multivibrator 35. a monostable multivibrator 35 triggered by the voltage signal V ₃
outputs a pulse wave _V4 with a preset pulse width _t2 . That is, the pulse generating means B is a means for generating a pulse V ₄ of a predetermined width t ₂ using the operation start (current generation) signal of the switch means (key-in switch) as a trigger, and inputs its output to the AND gate 32 .

The AND gate 32 performs an AND operation on the outputs V ₁ and V ₄ . In other words, when high level signals of V ₁ and V ₄ are input at the same time, a high level voltage signal is generated.
_V5 is output.

The time t ₁ from when the output voltage V ₂ of the delay means B is connected to the power supply terminals _{c 1} and _{c 2} until it reaches the trigger level of the AND gate _{32 is} determined by If the value is set to be longer than the output pulse width _t2 of the monostable multivibrator 35, the output voltage _V5 remains at a low level due to the characteristics of the AND gate 32, and the timer circuit 3
6 never starts.

Therefore, even if the power terminals c _{1 and} c ₂ are reconnected with the key-in switch 10 closed, the activation signal S ₁ is not output from the timer circuit 36 to the control means 4, and the relay switch 8 is turned off. As a result, the glow plug 7 is not energized, and naturally no sparks fly between the power terminals c ₁ and c ₂ .

Normal key-in-glow operation or the above key
Power terminal c ₁ when the in-switch is closed,
c ₂ To control the glow plug energization after connection, it is sufficient to insert the engine key into the switch means, or to remove the engine key from the switch means and insert it again into the switch means. Taking the latter case as an example, after connecting the power terminals c ₁ and c ₂ , remove the engine key, insert it again, and close the key-in switch 10, which turns on the pulse generating means B. A pulse is generated from
However, the output of this pulse signal V ₄ is output from the power supply terminals c ₁ and c ₂
Since there is an artificial time from connection to re-insertion of the engine key, the electrical delay time t ₁ has elapsed, and the output signal V ₅ of the AND gate 32 is a pulse signal similar to the output pulse of the monostable multivibrator 35. The timer circuit 36 is activated by the pulse, and the power supply voltage via the terminal _a2 appears at its output _V0 , which activates the control means 4 and turns on the relay switch 8 for a predetermined time _tT , causing a glow. Plug 7 is energized and heated.

The time chart in Figure 4 shows the series of operations in which power terminals c ₁ and c ₂ are reconnected with the key-in switch 10 closed, and then the engine key is reinserted and the key-in glow is performed. show.

It goes without saying that the glow plug heating time _tT may be controlled to be constant by the timer circuit 36, or may be controlled by the control means 4 according to the engine operating state as described above.

As is clear from the above, the glow energizing means C referred to in the present invention refers to the AND gate 3 in this embodiment.
2. It includes a timer circuit 36, a control means 4, and a relay switch 8, and it is also possible to omit either the timer circuit 36 or the control means 4.

FIG. 5 shows another embodiment of the present invention. In the previous embodiment, the current supplied to the control means 4 was supplied through the key-in switch 10, so if the contact current capacity of the key-in switch 10 was larger than the current consumption of the control means 4, Therefore, the key-in switch 10 also inevitably becomes large, which is disadvantageous in terms of vehicle layout and increases costs.

In contrast, in this embodiment, a terminal _a6 directly connected to the power supply 1 is provided independently for supplying power to the control means, while the key-in switch 10 is a key-in switch.
It is dedicated for controlling the timer circuit 25.
This allows the key-in switch 10 to be small in both current capacity and size.

Further, a modification of the connection method between the glow plug 7 and the relay switch 8 (the portions surrounded by broken lines in FIG. 5) is shown in FIGS. 6 and 7.

In the example shown in FIG. 6, another relay switch 8A is connected in parallel to the relay switch 8,
A resistor _R11 is interposed between the relay switch 8A and the glow plug 7. Then, the control device 3 selects the relay switch circuit to be used. If you select relay switch 8, you can quickly heat up the glow plug 7, and select relay switch 8A.
If you select resistance R ₁₁ minutes, glow plug 7
Since the calorific value of the heat is reduced, it can be used for keeping warm after preheating is completed. Of course, the circuits of both relay switches 8 may be energized at the same time.

What is shown in FIG. 7 is a plurality of glow plugs 7A.
are divided into two groups 7a and 7b, and these are connected in parallel to each other and connected in series to a relay switch 8.A relay switch 8B connected in parallel to the relay switch 8 is normally grounded with the glow plug 7b and connected to the power supply when energized. Both glow plugs 7a, 7 for 1
Wire b so that they are connected in series.

As a result, the resistance in the embodiment shown in FIG.
Power is saved because _R11 does not dissipate heat, and the control device 23 controls relay switches 8 and 8 in the same manner as above.
By controlling the operation of the glow plug 7A, the parallel connection and the series connection of the glow plugs 7A are switched, and the glow plugs 7A are switched for rapid heating and thermal insulation heating.

<Effects of the invention> As described above, according to the invention, in the key-in-glow method, if the power supply terminal is reconnected while the switch means consisting of the key-in switch is closed, the power supply voltage will go high. Focusing on the fact that the current starts to flow in the switch means (output from the pulse generation means) at the same time as the voltage rises to the level, the rise of the power supply voltage is delayed by the delay means, and there is a gap between the output pulse of the pulse generation means and the output pulse of the pulse generation means. Since the AND condition is not established, it is possible to reliably prevent the generation of glow current when reconnecting the power terminal with the engine key inserted, thereby preventing damage to the power terminal or cable terminal, and making the power terminal connection work safer. .

Further, the delay means and the pulse generation means do not require any relay switch, and the glow energizing means for energizing and heating the glow plug under the AND condition of the outputs of the two means is also equipped with a relay switch for directly driving the glow plug. No relay switch required. Therefore, it has the advantage of being able to reduce the size of the device, improve its reliability, and reduce its cost.

[Brief explanation of the drawing]

FIG. 1 is a circuit diagram of a key-in timer circuit showing an embodiment of a part of the delay means, pulse generation means, and glow energization means which are the main parts of the present invention, and FIG. 2 is a circuit diagram of the same key-in timer circuit. A configuration block diagram of a control device incorporating a timer circuit and including a control means which is a part of the glow energizing means, FIGS. 3 and 4 are time charts showing the operation of the above embodiment, and FIG. 5 is a diagram showing the operation of the above embodiment. Schematic configuration diagrams showing two embodiments, FIGS. 6 and 7
The figures are a circuit diagram showing an example of the connection between a glow plug and a relay switch for driving the glow plug, respectively, FIG. 8 is a schematic configuration diagram showing a conventional example of a glow plug energization control circuit, and FIG.
The figure is a time chart explaining the operation of the same. 1...Power supply, 2...Ignition switch,
7... Glow plug, 8, 8A, 8B... Relay switch, 10... Key-in switch, 23
...Control device, 25...Key-in timer circuit, A...Delay means, B...Pulse generation means, C
...Glow energizing means, 31...Time constant circuit, 35
... Monostable multivibrator, 36 ... Timer circuit, c ₁ , c ₂ ... Power supply terminal.

Claims (1)

[Scope of utility model registration request] In a key-in-glow type glow plug energization control device that applies power supply current to a glow plug via a switch that operates with the engine key inserted into the switch device, the rise of the power supply voltage signal is controlled for a predetermined time t ₁ a delay means for outputting the pulse after a delay; a pulse generation means for generating a pulse for a predetermined time (t ₂ >t ₁ ) using the start of operation of the switch means as a trigger, which is configured independently of the delay means;
A glow plug energization control device for an engine, comprising: glow energization means that energizes the glow plug with power supply current for a predetermined period of time when two high-level output conditions of the pulse generation means of the delay means are satisfied.