JPS6353376B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a heating device, and more particularly to a control device for a vehicle heating device that protects the power supply voltage.

<Prior Art> As a conventional heating device, there is, for example, one disposed in an intake passage of an internal combustion engine to heat intake air and improve combustion. As a conventional example, JP-A-57-
Examples include those disclosed in Publication No. 49054.

In such a conventional example, a heater consisting of a positive temperature coefficient thermistor, a ceramic heater, etc. disposed in an intake passage is configured to stop energizing the heater when the intake air temperature or the engine cooling water temperature downstream of the heater reaches a predetermined value or higher. The method is adopted. This prevents the intake air from being overheated, thereby suppressing a decrease in the efficiency of filling the intake air into the combustion chamber, or reducing the electrical load.

<Problems to be Solved by the Invention> By the way, the inrush current when the heater is turned on is large, for example, about 30 to 40 A, as shown in Figure 2.
Even in steady state, a large current of about 20A is required. Therefore, if the power supply voltage of the engine is reduced, most of the current will be consumed for heating the heater, but the conventional heating device described above is , the heater was controlled solely from the standpoint of preventing overheating.

For this reason, when the power supply voltage is low, the voltage supplied to the engine decreases, causing the starter to not rev up and causing starting problems, and even while the engine is running, the functions of the electronic and electrical components that control the engine are impaired. This has the disadvantage that malfunctions or engine stalls are more likely to occur.

Furthermore, since heater heating is performed even when the engine rotational speed is below a predetermined value, such as when the engine stalls, the power supply voltage drops significantly.

In view of the conventional inconveniences, the present invention supplies electricity to the electric heater when the engine rotational speed and the power supply voltage are each greater than a predetermined value when the engine is not cranked, while the engine rotational speed or the power supply voltage is at least If one side reaches a certain condition where a drop in the power supply voltage becomes a problem due to heating by the heater, the power supply voltage is protected by stopping the heating of the electric heater to prevent any inconvenience from occurring in subsequent engine cranking. At the same time, the purpose is to secure the power supply voltage for the engine control system.

<Means for Solving the Problems> For this purpose, in the present invention, the heating device includes an electric heater, a power source, voltage detection means for detecting the voltage of the power source, and a rotation sensor for detecting the engine rotation speed.
means for detecting a non-operating state of the starter; and heating control means for controlling the heating current of the electric heater;
When the starter is in a non-operating state, the heating control means energizes the electric heater when the engine rotational speed and the power supply voltage are each higher than a predetermined value, and controls the electric heater when the engine rotational speed is below a predetermined value. The electric heater is configured to cut off power supply to the electric heater after a certain period of time or when the power supply voltage is below a predetermined value.

<Function> As a result, when the starter is inactive and the power supply voltage and engine speed are sufficient, the electric heater is properly energized, but once the power supply voltage drops below a predetermined value, Even if the power supply voltage is above a predetermined value, if the engine speed remains below the predetermined value with a significant drop in the power supply voltage for a predetermined period of time, the electric heater will be deenergized. Don't do it.

<Example> Examples of the present invention will be described below based on the drawings. In this embodiment, the present invention is applied to an intake air heating device.

In FIG. 1, an intake throttle valve 3 is disposed in an intake passage 2 of an internal combustion engine 1, a fuel injection valve 4 is disposed upstream of the intake throttle valve 3, and a positive temperature coefficient thermistor having a honeycomb shape is disposed downstream of the intake throttle valve 3. An electric heater 5 is provided.

The positive electrode of the electric heater 5 is connected to the positive terminal of a battery 6 as an engine power source, and the negative electrode of the electric heater 5 is grounded via a relay 7. The coil of the relay 7 is ON/OFF controlled by an electronically controlled heating control unit 10.

Further, cooling water passages 11 are provided to heat the riser portion of the intake passage 2, and, for example, a detection signal from a temperature sensor 12 that detects the temperature of the cooling water in these cooling water passages 11 is used as a heating control means. It is input to the water temperature monitor circuit 10a (FIG. 3) of the control unit 10. The configuration up to now is the same as the conventional device.

Furthermore, in the embodiment according to the present invention, the heating control unit 10 includes an air flow meter 13 for detecting the amount of intake air, a negative pressure sensor 14 for detecting the intake negative pressure, and a rotation sensor for detecting the rotation speed of the crankshaft (engine rotation speed). 15, and a starter switch 16 and an ignition switch 17 which are means for detecting the non-operating state of the starter.
A switching signal to the ON position is input as the engine operating state. Then, the + terminal of the battery 6 is connected to the heating control unit 1 via the ignition switch 17.
0, a new power supply voltage detection means is provided, and the heating control unit 10 is connected as shown in FIG.
A voltage monitor circuit 10b provided inside monitors whether the power supply voltage is below a predetermined value. The results of this monitoring are then sent to the heater energization control circuit 10c.
is input, and the heating stop means (FIG. 1, 20) provided in the heater energization control circuit 10c cuts off the energization of the electric heater 5 when the engine rotational speed and power supply voltage satisfy predetermined conditions.

The heating control unit 10 is further provided with various monitor circuits such as an intake air amount monitor circuit 10d, an intake negative pressure monitor circuit 10e, a rotational speed monitor circuit 10f, and a starter switch monitor circuit 10g.
Corresponding signals from the respective meters, sensors, and switches 12 to 16 are received, processed, and input to the heater energization control circuit 10c.

Next, the operation of the above embodiment will be explained using the flowchart shown in FIG. The flowchart shown in the figure is designed to be repeated at predetermined intervals, for example, every second, by means of a clock.

When the ignition switch 17 is closed,
The heating control unit 10 receives detection signals from a temperature sensor 12, an air flow meter 13, a negative pressure sensor 14, a rotation sensor 15, a battery 6, and a starter switch 16. Cooling water temperature T _W used as
The corresponding monitor circuits 10a, 10b, and 10f monitor the power supply voltage _VB and the engine rotational speed N, and determine whether the electric heater 5 is energized or not.

First, read the above T _W , V _B and N in S ₁ , and then read in S ₂
This value of N is stored in memory.

Detected water temperature T _W and set value T (= about 50℃, for example) at S ₃
If T _W is lower than T, it is determined in _S4 whether the starter switch 16 is ON or not.

If it is determined that cranking is in progress, it is determined in _S5 whether the power supply voltage _VB is lower than _V2 , for example, approximately 8V, and if it is higher than 8V, the heater energization control circuit 10c is activated, and S ₆ , the electric heater 5 is energized and heated to facilitate cranking.

If the starter switch is not ON in _S4 , that is, if the starter is inactive, it is determined in _S7 whether the detected rotational speed N _i is larger than the set value _N1 , for example, about 20 rpm.

If it is not large (N ₁ ≧N _i ), there are two possibilities: either before cranking or engine stalling. and _S8
Read out the previously detected rotational speed N _i-1 from the memory, compare N _i and N _i-1 , and if N _i < N _i-1 , you know that the engine has stalled for the first time, and N _i ≥ N _i If it is _-1 , it is known that the state is before cranking or that the stalled state is continuing.

If the engine stalls for the first time, or as a result of comparing the count t in _S10 with a predetermined number of times (time) _t1, for example, 5 seconds, the predetermined time _t1 has not elapsed since the ignition switch 17 was turned on or the engine stalled. If this is found, check in _S14 that the power supply voltage _VB is greater than the predetermined value _V1 , for example 10V,
The electric heater 5 immediately starts energizing and heating via the heater energization control circuit 10c, or continues heating if it is already heating. As a result, if the engine is before cranking, the heater temperature at the start of cranking is sufficiently raised to improve startability, and if the engine is stalled, restarting is facilitated.

However, if t≧t ₁ , it means that a long time has passed since the ignition switch 17 was turned on and the engine stalled again, so this signal is sent to the electric heater 5 via the heater energization control circuit 10c. Then, in _S13 , energization heating is stopped to stop wasting power supply voltage and prevent so-called battery build-up.

If you find that the engine has stalled for the first time in S ₉ , reset the counter in S ₁₁ and try again.
If the counter number is less than _t1 in _S10 , the counter is incremented (t←t+1) in _S12 and the elapsed time is measured.

If N ₁ <N _i in S ₇ , the engine continues to rotate in a cold state, so confirm that the power supply voltage V _B is greater than V ₁ , for example, 10 V, and continue heating the electric heater 5. .

If the engine is not cranking, that is, the ignition switch 17 is ON and the engine is not cranking or the engine has stalled for more than a predetermined time (S ₄ , S ₇ ,
S ₈ , S ₉ , and S ₁₀ ), or while the engine is rotating,
If it is found in _S14 that the power supply voltage _VB is lower than _V1 , the electric heater 5 is turned off via the heater energization control circuit 10c.
Priority will be given to immediately stopping energized heating and fully operating the engine control equipment.

If it is detected in _S3 that the cooling water temperature T _W is equal to or higher than T, the electric heater 5 is turned off to protect the power supply voltage since it is not necessary to heat the intake air.

When one control routine is completed, the detected rotational speed signal N _i is stored as N _i-1 .

Therefore, as can be seen from the above, the electric heater 5
The conditions for turning off are: when the power supply voltage V _B drops below V ₁ , when the cooling water temperature rises above T°C, and when the engine stalls or before cranking and a predetermined period of time has passed after the ignition switch 17 is turned on. be. If the power supply voltage drops, turn on the electric heater 5.
The electric heater 5 is turned off and stands by, and the electric heater 5 is energized as soon as the voltage rises.

The reason why V ₁ and V ₂ are made different is to take into account the power supply voltage drop during cranking. Further, the engine stall may be determined using an intake air amount signal or an intake negative pressure signal. Although the electric heater in the embodiment has been described as an electric heater for heating intake air, the present invention can also be applied to control other electric heaters (for example, an electric heater provided in a vehicle window).

It goes without saying that the energization control of the electric heater may be performed based on other engine state signals.

<Effects of the Invention> As described above, according to the present invention, when the starter is inactive, the heating control means energizes the electric heater when the engine rotation speed and the power supply voltage are each higher than predetermined values, while the engine rotation After the speed remains below a predetermined value for a predetermined period of time or when the power supply voltage is below a predetermined value, the power to the electric heater is cut off. On the other hand, when the engine speed is low, such as when the engine stalls, the power supply voltage does not have to bear the large power load of the electric heater, which prevents starting problems due to insufficient starter rotation and engine control. Other electricity/
It is possible to prevent engine control failure or engine stalling due to loss of function of electronic components.

[Brief explanation of the drawing]

FIG. 1 is a configuration diagram showing an embodiment of a heating device according to the present invention, FIG. 2 is a graph showing transient current characteristics of the same electric heater, and FIG. 3 is a graph showing various detection means and electric heaters shown in FIG. A block diagram showing the relationship with the heating control means, and FIG. 4 is a flowchart of the heating control means mentioned above. 1... Internal combustion engine, 2... Intake passage, 3... Intake throttle valve, 5... Electric heater, 6... Battery, 1
0... Heating control unit, 10a... Water temperature monitor circuit, 10b... Voltage monitor circuit, 10c... Heater energization control circuit, 17... Ignition switch, 20... Heating stop means.

Claims (1)

[Claims] 1. An electric heater, a power source, a voltage detection means for detecting the voltage of the power source, a rotation sensor for detecting the engine rotation speed, a means for detecting the non-operating state of the starter, and controlling the heating current of the electric heater. heating control means, wherein when the starter is inactive, the heating control means energizes the electric heater when the engine rotation speed and power supply voltage are each greater than a predetermined value, while the engine rotation speed is below a predetermined value. A heating device configured to cut off power to the electric heater after this state continues for a predetermined period of time or when a power supply voltage is below a predetermined value.