JP2001329889A - Fuel injection quantity control device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fuel injection quantity control device improving the low temperature starting performance of an engine. SOLUTION: This fuel injection quantity control device for controlling fuel injection quantity when the engine 3 is started at a low temperature is provided with an engine speed detecting means 6 for detecting the speed of the engine 3, and a control means 2 for controlling fuel injection quantity until the speed of the engine becomes a specified according to the specified correlation between the speed of the engine 3 and the fuel injection quantity based on the engine speed detected by the engine speed detecting means 6.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fuel injection amount control device for improving low temperature startability of a diesel engine or the like.

[0002]

2. Description of the Related Art In a diesel engine, it is necessary to inject an appropriate amount of fuel at the time of starting. In order to obtain an initial explosion at the time of starting cranking, an opening of a rack driven by a governor actuator (rack) is required. Volume) must be increased. Conventionally, since the rack amount is constant over the starting time, the fuel injection amount increases as the engine speed increases.

[0003]

As described above, in the conventional diesel engine, the amount of racks is increased in order to obtain the first explosion. In this case, especially at low temperatures, when the same amount of fuel is injected as at room temperature, the fuel deteriorates and smolders, so that the engine does not start. Further, when the rack amount is adjusted so that the fuel injection amount becomes optimal at the time of the rise of the rotational speed at a low temperature, the first explosion cannot be obtained and the engine cannot be started.

For this reason, conventionally, when a low temperature start mode for a low temperature start is set in a vehicle, the engine is started by appropriately reducing the fuel injection amount from that at normal temperature.

However, in this case, although the fuel injection amount at a low temperature is reduced, the fuel injection amount is constant from the initial explosion to the rising of the rotation speed, so that the state of excessive fuel at the rising of the rotation speed is not solved. Further, when the low temperature start mode is erroneously set at normal temperature, there is a problem that the initial explosion cannot be obtained and the engine cannot be started because the fuel injection amount is small.

[0006] It is an object of the present invention to provide a fuel injection amount control device that improves the low temperature startability of an engine.

[0007]

Means for Solving the Problems To solve the above problems and achieve the object, a fuel injection amount control device of the present invention is configured as follows.

(1) A fuel injection amount control device according to the present invention is a fuel injection amount control device for controlling a fuel injection amount when the engine is started at a low temperature, a rotation speed detecting means for detecting a rotation speed of the engine, Control means for controlling the fuel injection amount to a specified rotation speed in accordance with a predetermined correlation between the engine speed and the fuel injection amount based on the rotation speed detected by the rotation speed detection means. ing.

(2) The fuel injection amount control device according to the present invention is the device described in (1) above, and the correlation is such that the fuel injection amount increases as the engine speed increases from the first explosion of the engine. Is increasing or decreasing.

[0010]

FIG. 1 is a block diagram showing a schematic configuration when a fuel injection amount control device according to an embodiment of the present invention is applied to a diesel engine of a vehicle.

As shown in FIG. 1, a starter switch 1 provided in a vehicle is connected to a controller 2 and a starter motor 4 of a diesel engine 3. The governor actuator 5 of the diesel engine 3 and the rotation speed detector 6 are connected to the controller 2. In the diesel engine 3, the starter motor 4 starts the operation, and the injection pump 8 according to the opening degree (rack amount) of the rack 7 driven by the governor actuator 5.
The fuel is injected from. The controller 2 stores a specified rotation speed and a correlation map described later.

FIG. 2 is a flowchart showing an operation procedure at the time of low temperature start in the injection amount control device. First, in step S1, a low-temperature start switch (air heater switch) provided on the vehicle is turned on by a driver to set a low-temperature start mode, and further, the starter key is set to a start position by the starter switch 1. In step S2, the controller 2 and the starter motor 4 are turned on.
become. By driving the starter motor 4, the diesel engine 3 is started.

Is performed.

In step S4, the controller 2 determines in step S4 that the rotational speed Ne of the diesel engine 3 detected by the rotational speed detector 6 exceeds the specified rotational speed.
Reference is made to a correlation map between the rotation speed Ne and the rack amount as shown in FIG. The controller 2 performs drive control of the governor actuator 5 according to the correlation map in step S5,
Forcibly control the rack volume.

Thereafter, when the rotation speed Ne exceeds the specified rotation speed in step S3, the controller 2 controls the normal operation of the governor actuator 5 in step S6.

FIG. 4 is a diagram showing a control situation when the diesel engine 3 is started at a low temperature by the injection amount control device. The relationship between the rack amount (injection amount) and the engine speed with respect to time is described in the present embodiment. The conventional example is shown in comparison. In FIG. 4, a represents the case of the present embodiment, and b represents
Indicates the case of the conventional example.

In this embodiment, when the controller 2 detects that the cranking has been started in the diesel engine 3 from the rotation speed Ne detected by the rotation speed detector 6, the controller 2 starts the start mode. In the period (1) shown, control is performed so as to increase the fuel injection amount (rack amount) in order to obtain the first explosion. That is, the period (1) is a period from the start of cranking to the first explosion. In this case, the controller 2
Performs the drive control of the governor actuator 5 according to the correlation map, and forcibly controls the rack amount.

Next, after the first explosion is obtained, the controller 2 controls the injection amount (rack amount) to reduce the injection amount (rack amount) so as to obtain an optimum injection amount for starting the engine speed in order to avoid smoldering due to excessive fuel. I do. The controller 2 determines that the rotation speed Ne detected by the rotation speed detector 6 is N1, N2,
The control is performed so that the fuel injection amount (rack amount) decreases as N3 is reached. That is, period (2) of FIG.
At the beginning of (4), the rotation speeds are N1, N2, and N3, and the injection amount decreases in each of the periods (2) to (4). In this case, the controller 2 controls the driving of the governor actuator 5 according to the rotation speed according to the correlation map, and forcibly controls the rack amount.

The controller 2 includes a rotation speed detector 6
When it is detected that the rotation speed Ne detected in step (b) has reached the specified rotation speed, the startup mode is terminated, and the governor actuator 5 is turned on in accordance with the engine rotation speed corresponding to the throttle opening.
Is performed to control the fuel injection amount.

As shown in FIG. 4, in the present embodiment, the fuel injection amount is not constant from the time of the initial explosion to the rising of the rotational speed but gradually decreases as in the conventional example. It becomes the optimal injection quantity for raising. This allows
Smoldering due to excessive fuel can be avoided. Further, from FIG. 4, it can be seen that in the present embodiment, since the injection amount is more appropriate than in the conventional example, the initial explosion and the rise of the rotation speed are faster.

It should be noted that the present invention is not limited to the above-described embodiment, and can be appropriately modified and implemented without changing the gist. For example, the governor actuator 5 according to the correlation map
In addition to the above-described drive control, the rack amount (injection amount) can be controlled stepwise so as to be appropriate for the engine speed without using a correlation map, in addition to forcibly controlling the rack amount.

[0022]

According to the fuel injection amount control device of the present invention,
By controlling the fuel injection amount as a function of the engine speed until the specified rotation speed is reached, the fuel injection amount is appropriate at low temperature start, so the first explosion and the rise of rotation are quicker, improving the cold startability of the engine Can be done.

According to the fuel injection amount control device of the present invention, smoldering due to excessive fuel can be avoided by gradually decreasing the fuel injection amount from the time of the first explosion to the rising of the rotation speed. Further, even when the low temperature start mode is erroneously set at the normal temperature, the fuel injection amount at the time of the first explosion, that is, at the time of cranking can be set to be large, so that the engine can be started.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a schematic configuration when an injection amount control device according to an embodiment of the present invention is applied to a diesel engine of a vehicle.

FIG. 2 is a flowchart showing an operation procedure of the injection amount control device according to the embodiment of the present invention.

FIG. 3 is a correlation map between a rotation speed and a rack amount according to the embodiment of the present invention.

FIG. 4 is a diagram showing a control situation at the time of low-temperature start of the diesel engine by the injection amount control device according to the embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Starter switch 2 ... Controller 3 ... Diesel engine 4 ... Starter motor 5 ... Governor actuator 6 ... Rotation speed detector 7 ... Rack 8 ... Injection pump

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Seiichi Mori 3000 Tana, Sagamihara-shi, Kanagawa Prefecture Mitsubishi Heavy Industries, Ltd. (72) Inventor: Naoto Kataoka 3000, Tana, Sagamihara-shi, Kanagawa M.H.I.I.Sagami High-Tech Co., Ltd. F-term (reference) KA05 LB11 LC10 MA11 NC02 NE06 NE15 PE01Z PF16Z

Claims (2)

[Claims] 1. A fuel injection amount control device for controlling a fuel injection amount at the time of a low-temperature start of an engine, a rotation number detection means for detecting a rotation number of the engine, and a rotation number detected by the rotation number detection means. Based on a predetermined correlation between the engine speed and the fuel injection amount,
A control unit for controlling the fuel injection amount until a predetermined rotation speed is reached. 2. The fuel injection amount control device according to claim 1, wherein the correlation is such that the fuel injection amount increases and decreases as the engine speed increases from the time of the initial explosion of the engine. .