JPS6337487Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to an injection timing correction device for a fuel injection pump that injects fuel by changing the fuel injection timing between engine startup and warm-up after engine startup.

The so-called bottle-type distribution fuel injection pump installed in diesel engines positions a timer piston according to the fuel pressure (feed pump discharge pressure), which increases in proportion to the engine speed, and retards the fuel injection timing. There is.

Conventionally, the injection timing was kept constant below a predetermined engine speed depending on the engine operating state (see Figure 1 a), or an auxiliary advance device was installed behind the timer piston to keep the injection timing constant only during the initial startup. Once the predetermined rotational speed is exceeded by giving an advance angle of
The injection timing will be the same as that of the engine speed, and if the rotation speed drops below idling, a certain amount of advance will be applied again (see Figure 1 b). This prevents the occurrence of

By the way, according to the applicant's experimental results, it was confirmed that in order to reduce the noise and white smoke generated due to such knocks, it is necessary to slightly change the injection timing at startup and warm-up. It was done.

However, with conventional devices, it is not possible to change the injection timing below a predetermined rotation speed, that is, between the extremely low speed range at startup and the warm-up range, and it is not possible to sufficiently suppress the noise and white smoke generation mentioned above. Nakatsuta.

On the other hand, for example, in Japanese Patent Laid-Open No. 54-31822, a wax pellet, which is a type of temperature-sensitive actuator, is connected to the timer piston, and the timer piston is forcibly moved in the advance direction by the stretching force of the wax pellet when starting at a low temperature. It has been proposed to keep it in place.

However, the characteristics of wax pellets tend to change due to wax deterioration due to overheating or aging, and there are slight variations in the operating characteristics even when new. As for engine timing, the optimum advance angle is not always achieved, and it is not possible to reliably obtain the optimum advance angle for both startup and warm-up. The drawback was that it was not suitable for

The present invention was developed by focusing on these conventional problems, and optimizes the amount of fuel injection advance for each operating condition during startup and warm-up to reduce noise and prevent white smoke. The purpose is to reliably control the amount.

To this end, the present invention provides a fuel injection pump for a diesel engine that is equipped with a timer piston that delays injection timing according to fuel pressure, and includes an operating state detection means that detects the engine operating state, a sensor that detects the cold engine state, A control device that controls fuel injection timing by comparing signals from the detection means and the sensor, and an advance angle correction drive device that drives a timer piston based on an output signal from the control device, and the advance angle correction The drive device includes a first piston rod that advances injection during startup, a second piston rod that advances injection during warm-up, and a first solenoid that drives the first piston rod based on a signal from the control device. A second solenoid also drives a second piston rod, and the fuel injection timing is changed stepwise and reliably by driving the solenoid at the time of starting the engine and during warm-up after starting.

Embodiments of the present invention will be described below based on the drawings.

In FIG. 2, 1 represents a fuel hydraulic timer section of a distribution type fuel injection pump equipped with a fuel injection timing advance angle correction drive device 2, and 3 represents an operating state detection unit that detects an operating state according to engine speed, etc. means, 4
Reference numeral 5 indicates an engine cooling water temperature sensor as a sensor for sensing a cold engine state, and 5 a control device that compares and controls the fuel injection timing based on signals from the operating state detection means 3 and the water temperature sensor 4.

The fuel-hydraulic timer section 1 includes a roller ring 8, which has rollers 7A to 7D arranged at equal intervals on which a cam ring of a plunger (not shown) rides, a cam screw 10 that positions the roller ring 8 via a timer clip 9, and an advance angle of the cam screw. It consists of a timer piston 11, an advance angle correction drive device 2, etc.

The timer piston 11 is slidably housed in the cylinder 12, and is biased in the direction of injection delay (to the right) by a spring 14 interposed in the left cylinder low pressure chamber 13 in the figure. Also, an oil hole 11A is formed for transmitting the fuel oil pressure in the pump housing 6 to the cylinder high pressure chamber 15 on the right side in the figure.

The present invention further includes a double cylindrical piston rod 1 that comes into contact with the right end 11B of the timer piston 11.
6 and 17 are provided, and the advance angle correction drive device 2 moves the rods 16 and 17 left and right to delay the amount of advance angle.

The advance angle correction drive device 2 includes a first solenoid 18 located on the outer periphery of the piston rod 16.
and a second solenoid 19 located on the outer periphery of the second hollow piston rod, and a spring 2 that biases these rods 16 and 17 in the retard direction.
0, 21, etc., and will be described later.
The timer piston 11 is positioned at a point that maintains a balance between the electromagnetic force and the biasing force of the spring in accordance with the value of the current supplied to the solenoids 18 and 19 from the solenoid.

The operating state detection means 3 includes a key switch 22 that is turned on manually before starting the engine, a regulator 23 that is turned on when an alternator (not shown) starts generating electricity after engine startup, an accelerator switch 24, a battery 25, etc. and transmits the operating status to the control device 5.

The control device 5 compares the signal from the water temperature sensor 4 and the signal from the operating state detection means 3, determines the amount of advance according to the engine speed, and advances the current corresponding to this amount of advance. The angle correction drive device 2 is energized.

Next, the action will be explained.

To start the engine, turn on key switch 22
Then, the control device 5 determines the fuel injection timing according to the extremely low speed rotation, and the amount of current corresponding to this is determined by the first
Solenoid 18 is energized.

As a result, the first piston rod 16 moves to the left, and as shown in FIGS. 2 and 3, the cam screw 10 is moved clockwise by an angle θ ₁ to advance the fuel injection timing and cause combustion (not shown). Ensure good ignitability indoors.

Next, after ignition, the engine enters an idling state,
Along with this, the alternator operates and regulator 2
3 is turned on (the potential at the neutral point rises). As a result, the control device 5 cuts off the energization to the first solenoid 18, while turning on the second solenoid 19 to move the hollow piston rod 17 to obtain an injection timing (angle θ ₂ ) further advanced than at the time of starting.

This warm-up advance angle is continued until the water temperature reaches a predetermined value or higher based on the output of the water temperature sensor 4, that is, until the warm-up is completed.

However, in this case, even during warm-up, when the accelerator pedal is depressed and the engine speed exceeds a predetermined value, the accelerator switch 24 is turned on and the advance angle θ ₂ is canceled.

Therefore, from now on, the piston 11 is displaced by the fuel pressure which changes according to the engine speed, and advance angle control is performed in proportion to the engine speed.

In addition, in FIG. 3, θ ₃ is the total advance angle amount when the engine speed reaches the maximum value.

In this way, in this invention, the fuel injection timing is advanced in stages below a predetermined rotation speed, that is, in the very low speed range at the time of starting and in the warm-up range after starting, which further improves engine starting performance. At the same time, it is possible to reduce the white smoke generated during warm-up and the noise associated with idle noise, and at the same time, it is possible to promote warm-up.

In addition, in the present invention, the first and second
Since the timer piston is driven by the piston rod and solenoid, there is no deterioration in characteristics and accuracy due to aging or deterioration of the advance angle correction means compared to the conventional system in which the advance angle is corrected using a wax pellet. In addition, since the appropriate injection advance amount is reliably obtained during startup and warm-up, excellent reliability is achieved, ensuring the effect of preventing noise and white smoke over a long period of time. .

[Brief explanation of the drawing]

Figures 1a and 1b are graphs showing the relationship between engine speed and fuel injection timing for each conventional example, Figure 2 is a schematic configuration diagram of an embodiment of the present invention, and Figure 3 is an embodiment of the present invention. 2 is a graph showing the relationship between engine speed and fuel injection timing. DESCRIPTION OF SYMBOLS 1...Fuel hydraulic timer section of the distribution type fuel injection pump main body, 2...Fuel injection timing advance angle correction drive device, 3...Operating state detection means, 4...Engine cooling water temperature sensor, 5...Control device.

Claims (1)

[Scope of utility model registration request] A fuel injection pump for a diesel engine equipped with a timer piston that delays injection timing according to fuel pressure includes an operating state detecting means for detecting an engine operating state, a sensor for detecting a cold engine state, and a signal from the detecting means and the sensor. A control device that controls fuel injection timing by comparing signals, and an advance angle correction drive device that drives a timer piston based on the output signal from this control device are provided. A first piston rod that advances the injection angle, a second piston rod that advances the injection angle during warm-up, a first solenoid that drives the first piston rod based on a signal from a control device, and a first solenoid that also drives the second piston rod. 1. A fuel injection timing correction device comprising a second solenoid that changes the fuel injection timing stepwise between when starting an engine and when warming up the engine after starting.