JP2610498B2 - Air heater control device for diesel engine - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an air heater control device that controls the output of an air heater of a diesel engine according to the starting state of the engine.

2. Description of the Related Art In an internal combustion engine such as a diesel engine, it is known to control the operating state of a fuel injection device using an electronically controlled governor, and a microcomputer built in a control unit of the electronically controlled governor is known. The fuel injection amount is controlled. On the other hand, a diesel engine is provided with an air heater, and pre-heating and after-heating are performed at the time of starting the engine to improve the startability thereof. This air heater is generally opened and closed by a simple on / off switch, so that preheating before driving the starter and afterheating after starting the engine are performed with the same output.

<Problems to be Solved by the Invention> The after-heat described above is effective for stabilizing the start-up of the engine and for preventing blue-and-white smoke which is likely to be generated immediately after starting. However, when the engine is not warmed up and the engine speed is low immediately after start-up, performing after-heating with the same capacity as that of pre-heating significantly discharges the battery, and the operation of the control unit becomes unstable due to a voltage drop. Was liable to cause an undesirable state. To avoid this,
For example, it is conceivable that two air heaters are provided and both of them are energized at the time of preheating, and only one is energized at the time of afterheating to reduce the output of afterheating. It is difficult to further control the operation of stopping the energization of the air heater in order to minimize the decrease in the battery voltage while the starter is being driven. There has been a problem that the overall cost increases.

Also, tractors, combine harvesters, fishing boats, etc. use large diesel engines with larger horsepower than those used for automobiles. Therefore, it is important to minimize battery discharge and deterioration.

The present invention focuses on a microcomputer built in a control unit of an electronically controlled governor, and controls the energization of an air heater by using the microcomputer to prevent the battery from being discharged and deteriorated. The purpose of this is to solve the problem.

<Means for Solving the Problems> In order to achieve the above object, according to the present invention, in a diesel engine provided with an electronically controlled fuel injection device that controls a fuel injection pump in accordance with the state of the engine, the engine is started. A starting state detecting means for detecting the state and an output control means for the air heater are provided to increase the output of the air heater during preheating and to reduce the output during afterheating, while stopping the energization of the air heater during driving of the starter, and during the preheating. The control of the air heater is such that the energization time of the air heater is set to a maximum when the engine temperature is equal to or less than a predetermined reference value, and is shortened as the temperature rises when the engine temperature exceeds the reference value. Is to be performed.

FIG. 1 is a diagram showing the configuration of the present invention. A is the control unit
A ₁ , an electronically controlled fuel injection device including a governor section including an actuator A ₂ and a fuel injection pump B, C is an engine,
D is a rotational speed detecting means, E is a fuel injection amount detecting means, F is an operating condition detecting means such as an accelerator operation amount, and G is a temperature detecting means of an engine or a fuel injection pump, which uses an electronically controlled governor. A conventional control unit for a diesel engine is configured, and according to the present invention, a starting state detecting means H and an output control means I for an air heater are incorporated in the system. J is a power supply such as a battery, and K is an air heater.

<Operation> The control unit A ₁ calculates a fuel injection amount in accordance with the detection results of the detection means D, E, F, and G, and operates the fuel injection pump B via the actuator A ₂ as a governor. Perform normal control operations. At the time of starting, the starting state detecting means H detects before or after the starter is driven, and the output control means I calculates the output of the air heater K and the energizing time to control predetermined preheating and afterheating.

<Example> Hereinafter, one example of illustration is described. FIG. 2 is a block diagram, FIG. 3 is a flowchart of a control procedure, and FIGS. 4 to 6 are diagrams showing various control maps.

In FIG. 2, 1A is a first air heater, 2A is an air heater relay for opening and closing the air heater 1A, 1B is a second air heater, 2B is an air heater relay for opening and closing the air heater 1B,
3 is a battery, 4 is a key switch, 5 is a temperature sensor, 6
Denotes a control unit, and 7 denotes an indicator light.

As the control unit 6, a control unit of an electronically controlled governor using a microcomputer as a main part is used as it is, and an input / output port 61, which provides control calculations and input / output instructions.
It comprises a CPU 62, a ROM 63 storing control programs and various data necessary for control calculations, a RAM 64 used for calculations, and the like.

A series circuit of the contact 21a of the air heater 1A and the air heater relay 2A, and the contact 21b of the air heater 1B and the air heater relay 2B
Are connected to the battery 3, and the coils 22a and 22b of the air heater relays 2A and 2B are connected to the input / output port 61 of the control unit 6, respectively. The ON circuit 4a and the starter circuit 4b of the key switch 4 and the temperature sensor 5
Are also connected to the input / output port 61. Although not shown, various sensors and actuators required as an electronically controlled governor are also connected to the input port 61 of the control unit 6. If necessary, the input unit of the input / output port 61 is provided with an A / D converter and the like, and the output unit is provided with a driver circuit and the like. The temperature sensor 5 detects the temperature of the engine or the fuel injection pump that greatly affects the startability, and is configured to detect, for example, the coolant temperature of the engine or the lubricating oil temperature of the fuel injection pump. The indicator light 7 is connected in parallel to the coil 22a of the relay 2A.

Next, the control procedure will be described with reference to the flowchart of FIG. 3 and the maps of FIG.

FIG. 3A shows the procedure of the preheat control. First, it is determined whether or not the key switch 4 is turned on in step S1, and if it is on, the temperature sensor 5 is turned on in step S2. The detection signal is input and the detected temperature T ₁
Pre-heat time t ₁ and the air heater output P ₁ corresponding to is calculated in step S3. As illustrated in FIG. 4, the preheating time is set to the maximum t0 when the temperature is equal to or lower than a certain reference temperature T0,
When the temperature exceeds, it is set to be shorter as the temperature becomes higher. Also, as illustrated in FIG. 5, the output of the air heater is set to be large during preheating and small during afterheating. In this embodiment, the output is adjusted by changing the number of energized air heaters. And 1B energization are selected.

Based on the above calculation results, in step S4, the coils 22a and 22b of the air heater relays 2A and 2B are energized, and the respective contacts 21a
And 21b are closed and energization of each air heater 1A, 1B and energization time t
The counting of p is started. Thereby, the indicator lamp 7 is turned on. Then, in step S5, the energizing time tp is the preheat time
If it is confirmed that reached t _1, the air heater relay 2A and energization is stopped each air heater 1A to 2B, the end is 1B energized, indicator light 7 preheat control ends off.

When the end of the preheat control is displayed by turning off the indicator light 7 in this way, the procedure of the afterheat control shown in FIG. 3B is started. First, in step S6, the starter, that is, the starter motor is driven.
, The detection signal of the temperature sensor 5 is input, and the detected temperature
After heating time t ₂ and the air heater output P ₂ corresponding to T ₂ it is calculated in step S8. However, in this embodiment, the after heat time is equal to the temperature Tmax as illustrated in FIG.
The temperature is set to a constant value (for example, 30 seconds) below (for example, 30 ° C.), and is set to zero for Tmax or more. Further, the output of the air heater is set to a value smaller than that at the time of preheating as described above. Here, energization of only the air heater 1A is selected.

Based on the above calculation results, the coil 22a of the air heater relay 2A is energized in step S9, the contact 21a is closed, energization of the air heater 1A and counting of the energization time ta are started, and the indicator lamp 7 is turned on. And energization time ta is after heat time
It is determined whether t ₂ has been reached. The ta <in the case of t ₂ is inputted detection signal of the temperature sensor 5 again in step S10, whether temperature T ₂ has reached the temperature Tmax is determined by the temperature rise after starting. Thus, the energizing time ta reaches the after-heat time t _2, or the temperature T ₂ reaches the temperature Tmax, power supply to the air heater relay 2A is stopped proceeds to step S11, the display lamp 7 ends the energization of the air heater 1A Is turned off, and the after heat control ends.

In the above embodiment, the output of the air heater is adjusted by changing the number of energized air heaters. However, the change of the number of energized air heaters is merely an example of output control. It is also possible to make it change. Further, in the embodiment, the afterheat time is set to be constant, but may be changed according to the detected temperature as in the case of the preheat.

<Effects of the Invention> As is apparent from the above description, the present invention controls the output of the air heater by using the control unit of the electronically controlled fuel injection device, and increases the output of the air heater during preheating.
The power supply to the air heater is stopped during the driving of the starter, and the power supply time of the air heater at the time of preheating is increased when the temperature is low, and shortened when the temperature is high.

Therefore, the preheat before the starter is driven is performed with a large output to improve the startability, and when the temperature is high, the preheat time is shortened, and while the starter is driven, the power supply to the air heater is stopped. After start-up, after-heat is performed for a required time with an appropriate output that is smaller than that during pre-heat to prevent extra discharge of the battery, and by suppressing deterioration, good startability is maintained over a long period of time. Control desirable as a diesel engine is performed in which the drop in battery voltage during machine operation is reduced to stabilize control, and blue-white smoke that tends to occur immediately after starting is prevented. Moreover, such an air heater control device can be easily realized by using the control unit of the electronically controlled fuel injection device as it is without using a separate control device and slightly changing the program thereof. This makes it possible to reduce the cost of the control device, and the ratio of the cost of the control device to the total cost is high. In the case of a relatively small working machine in which a large battery cannot be mounted, it is particularly effective.

[Brief description of the drawings]

1 is a diagram showing the configuration of the present invention, FIG. 2 is a block diagram of one embodiment of the present invention, FIG. 3 is a flowchart of a control procedure, and FIG. 4 is a diagram showing an example of the relationship between temperature and preheating time. FIG. 5 is a diagram showing an example of the relationship between the output at the time of preheating and the output at the time of afterheating, and FIG. 6 is a diagram showing an example of the relationship between the temperature and the afterheating time. 1A, 1B …… Air heater, 2A, 2B …… Air heater relay, 3
... battery, 4 ... key switch, 5 ... temperature sensor, 6 ... control unit, 21a, 21b ... contact, 22a, 22b ... coil, 62 ... CPU, 63 ... ROM.

Claims (1)

(57) [Claims] In a diesel engine provided with an electronically controlled fuel injection device for controlling a fuel injection pump in accordance with the state of the engine, a starting state detecting means for detecting a starting state of the engine and an output control means for an air heater are provided. The output of the air heater is increased during preheating and decreased during afterheating, and the energization of the air heater is stopped during the operation of the starter. The air heater control device for a diesel engine, wherein the control is performed by using the control unit of the electronically controlled fuel injection device to control the maximum value when the temperature exceeds the reference value and to shorten the temperature as the temperature increases.