JPS626295Y2 - - Google Patents

Description

[Detailed Description of the Invention] This invention is an improvement of an engine starting assist device that controls the temperature of glow plugs in diesel engines and the like.

First, a conventional device of this type is shown in FIG.
3, a comparator 24, and an output section 25. 3 is an indicator lamp controlled by the output of the output section 25; 4 is a first glow relay;
5 is a second glow relay; 6 is a dropping resistor connected in series to the second glow relay 5;
7 is a sensing resistor connected in series to the resistor 6; 8 is a glow plug; 9 is a water temperature switch for detecting engine cooling water temperature; and 10 is a battery for a DC power source. Figure 2 is a timing chart for explaining the operation of the device shown in Figure 1. Figure a shows the case when the water temperature is below 50℃, Figure b shows the case when the water temperature is over 50℃, and each A indicates the ignition. B is the indicator lamp, C is the first glow relay, D is the second glow relay, and E is the glow plug temperature timing chart.

Next, the operation will be explained. First, the water temperature is 50℃.
In the following cases, the water temperature switch 9 will turn OFF.
When the ignition switch 1 is in the ON position as shown in Fig. 2 a and b, the indicator lamp 3 lights up via the controller 2 as shown in Fig. 2 a and b, and the coil of the first glow relay 4 also lights up. Current flows and turns on the contacts as shown in Figure 2 a and c.
let As a result, the current from the battery 10 passes through the first glow relay 4 and the sensing resistor 7 and causes the glow plug 8 to become red hot. The energization time to the indicator lamp 3 is fixed, but at the same time as it turns off as shown in Fig. 2 a and b, the indicator lamp 3 turns off as shown in Fig. 2 a,
Turn ignition switch 1 to ST position as shown in A and start the engine. In this position, the indicator lamp 3 lights up again as shown in Fig. 2 a and b, and the first glow relay 4 also operates, while the second glow relay 5 also operates as shown in Fig. 2 a and d. The temperature of the glow plug 8 continues to rise gradually. Furthermore, in this state, the glow plug 8 is moved to the second position.
When the target temperature is reached as shown in Figures a and E, the first glow relay 4 is automatically turned off by the controller 2 as shown in Figures 2a and C, and the second glow plug 8 is turned off. Only glow relay 5 is available.
Once the engine has started, return ignition switch 1 to the ON position, and at the same time turn ignition switch 2 to the ON position.
The glow relay 5 and indicator lamp 3 are
It becomes OFF. Next, we will explain the case where the water temperature is 50℃ or higher. In this case, the water temperature switch 9 is
As shown in Fig. 2b and b, the indicator lamp 3 is lit for a short time, the first glow relay 4 is not turned on, and the glow plug 8 is energized only to the second glow relay 5. Become.

By the way, since the conventional glow plug control device is configured as described above, a dedicated sensing resistor 7 is required to detect the resistance value due to temperature change of the glow plug 8, and there are many components and the control operation is difficult. It's complicated. Moreover, the voltage drop caused by the sensing resistor 7 acts as a power loss when the capacity of the battery 10 decreases or when the voltage of the low-temperature battery 10 decreases, and thus becomes a factor that prevents the temperature of the glow plug 8 from rising at the time of starting. Also, water temperature 50
If the temperature is below ℃, turn on ignition switch 1.
After setting the engine to the position, it is necessary to wait for a certain period of time until the indicator lamp 3 goes out, and since this time assumes the worst case for starting, there are disadvantages such as having to wait for a certain period of time even when it is not necessary.

This invention has been made to eliminate the drawbacks of the conventional devices as described above, and its object is to provide an engine starting aid which detects the resistance of the glow plug caused by temperature changes by passing a constant current through the glow plug, and determines the optimum preheating time for the glow plug based on the detected resistance and the engine cooling water temperature. After the glow plug preheating is completed, a dropping resistor is turned on to stably preheat the glow plug, thereby enabling a diesel engine to be started easily in a short time while at the same time protecting the glow plug.

An embodiment of this invention will be described below with reference to FIGS. 3 and 4. In FIG. 3, 12 is a controller, 13 informs the driver that the preheating period is in progress, for example, a red indicator lamp A, and 14 informs the driver that the engine can be started. For example, green indicator lamp B, 31
36 indicates the configuration of the controller 12, and 31
32 is an input section, 32 is a control section, 33 is a timer, 34 is a detection section, 35 is an output section, and 36 is a constant current circuit. 41 is a water temperature sensor that detects the engine cooling water temperature, and 42 is, for example, a regulator L terminal that detects that the engine has started normally.

FIG. 4 is an operation timing chart for explaining the operation of the device shown in FIG. C is the indicator lamp A, C is the indicator lamp B, D is the regulator L terminal, E is the first glow relay, F is the second glow relay, and G is the time chart of the glow plug temperature.

Next, the operation will be explained. When the ignition switch 4 is turned on, a constant current is supplied from the constant current circuit 36 to the glow plug 8 for a short time, and a voltage proportional to the resistance value of the glow plug 8 at that time is detected by the detector 34. At the same time, the current engine condition is determined based on the signal from the water temperature sensor 41, and it is determined whether the water temperature is below or above the set value. First, to explain the case where the water temperature is below the set value, the voltage detected by the detector 34 is determined by the control unit 32 to be valid because the value of the water temperature sensor 41 is lower than the set value, and is sent to the timer 33. Ru. Here, the length t ₁ of the timer is determined by the value set by the detection voltage, and the indicator lamp A13 lights up for t ₁ as shown in Fig. 4 a and b, and at the same time, as shown in Fig. 4 a and ho. The first glow relay 4 turns on,
Current flows from the battery 10 to the glow plug 8,
The temperature of the glow plug 8 rises as shown in FIGS. 4a and 4g. Note that t ₁ is a value that is optimally set according to the resistance value of the glow plug 8 so that the temperature of the glow plug 8 becomes the target temperature. Next, after _t1 has elapsed, the indicator lamp A13 goes out. At the same time, the first glow relay 4 is also turned off, and it is confirmed by the signal from the constant current circuit 36 that the glow plug 8 is within the target temperature range. If not, the above operation is repeated again at t ₁ which is shorter than t ₁ described above, and the operation continues until the target temperature range is reached. At this point, the indicator lamp B14 lights up, and at the same time, the second glow relay 5 turns on, and power is supplied to the glow plug 8 via the dropping resistor 6, so that the stable preheating region is entered. This stable preheating time is defined as the time _t2 until the ignition switch 1 is placed in the ST position. this t ₂
For example, set the maximum value to 30 seconds. When ignition switch 1 is placed in ST, the second glow relay 5 is activated regardless of the previous t ₂ .
to heat the glow plug 8 again. Next, when the engine is driven, the regulator L terminal 42
The indicator lamp B14 is turned off and the timer _t3 is activated. This value is a function of t _1. After t ₃ hours, the second glow relay 5
It turns off and the glow plug 8 is no longer energized.

Next, if the water temperature is above the set value, the situation will be as shown in Figure 4b, the indicator lamp A13 will light up for a short time _t1 to check the disconnection function, the first glow relay 4 will not turn on, and the others will not turn on. The same operation is performed when the water temperature is below the set value.

In the above embodiment, when determining the timer _t1 , the engine cooling water temperature was detected and the switch was opened and closed to change the timer _t1 . A similar effect is achieved when t ₁ is determined using both the resistance values of the glow plugs. Alternatively, instead of making the determination of the timer t ₁ of the indicator lamp A13 variable by the glow plug resistance value, the timer length can be fixed (however, it can be changed by the water temperature switch), and the timer t 1 of the first glow relay glows only for ₁ hour. The same effect can be obtained by making it depend on the resistance value of the plug, or even by fixing _t3 of the second glow relay (however, it can be changed by the water temperature switch). Also, although _t3 is provided when the water temperature is above the set value, the same effect can be achieved even if it is not provided.

As described above, this invention uses a constant current to extract the resistance change of the glow plug as a temperature change, and also uses a dropping resistor to protect the glow plug, so the system is inexpensive and the glow plug is durable. It also has the advantage of being able to heat up quickly. Further, rapid heating is performed only when the engine cooling water temperature is low, and when the cooling water temperature is high, only stable preheating is performed without rapid heating, which is effective in protecting the glow plug and saving electrical energy.

[Brief explanation of the drawing]

1 is a circuit configuration diagram showing a conventional device, FIGS. 2a and 2b are operation timing charts for explaining the operation of FIG. 1, and FIG. 3 is a circuit configuration diagram showing an embodiment of this invention. 4a and 4b are operation timing charts for explaining the operation of FIG. 3. In the figure, 4 is a first glow relay, 5 is a second glow relay, 6 is a dropping register,
8 is a glow plug, 34 is a detector, and 36 is a constant current circuit. In addition, in the figures, the same reference numerals indicate the same or corresponding parts.

Claims (1)

[Scope of utility model registration request] Constant current circuit that passes constant current to the glow plug,
A detection circuit that detects the resistance value corresponding to the temperature change of the glow plug, a water temperature sensor that detects the engine cooling water temperature, a start detection means that detects engine starting, and the above-mentioned resistance when the engine cooling water temperature is below a predetermined value. a first glow relay that heats the glow plug to a target temperature by directly applying a power supply current to the glow plug for a predetermined time corresponding to the value; a dropping resistor connected in series to the glow plug; If the temperature is below the predetermined value, the above predetermined time has elapsed, and if the engine cooling water temperature is above the predetermined value, the glow plug is energized via the dropping resistor without waiting for the predetermined time until the predetermined time after the engine is started. An engine starting auxiliary device comprising a second glow relay that performs preheating.