JPS5845581B2 - Diesel engine fuel injection timing control device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a fuel injection timing control device for a diesel engine that ensures starting when the engine is cold.

Conventionally, for example, in a diesel engine equipped with a distributed fuel injection pump, the normal fuel injection timing was controlled by controlling injection according to the discharge pressure of a low-pressure (primary) fuel pump driven by a pump shaft or the centrifugal force of a rotating governor. This is done by automatically displacing a hydraulic piston for timing control.

Furthermore, when the driver needs it, such as when the engine is cold,
A cam that contacts one end of the hydraulic piston is manually operated via an arm and a cable to forcefully displace the hydraulic piston and advance the fuel injection timing.

This will be explained in more detail based on FIGS. 1 to 3.

1 and 2 show a conventional distribution type fuel injection pump and injection timing control device, in which 1 is a fuel injection pump shaft, 2
is a low pressure pump, 3 is a speed governor, 4 is an injection timing control device, 5
1 is a high-pressure pump, 6 is a discharge valve, T is a rotating disk, 8 is a roller, 9 is a hydraulic piston, 10 is a cam, and 11 is an arm.

In addition, in the cross-sectional view of FIG. 1, for convenience, the low pressure pump 2
The injection timing control device 4 is shown rotated by 90 degrees.

First, when the bowl pump 2 is driven by the shaft 1, fuel is sucked in through the passage 12 and discharged into the passage 13.

The passage 13 communicates with a fuel chamber 14 , and pressurized fuel by the low-pressure pump 2 is supplied to the high-pressure pump 5 from the passage 15 via the fuel chamber 14 , and at the same time, from the passage 16 to the hydraulic piston 9 .
It acts on one end 9A of.

Now, when the suction port 5A of the high pressure pump 5 and the notch 5C of the plunger 5B that moves integrally with the disk 7 coincide, the fuel pressurized by the low pressure pump 2 enters the cylinder 5D.

Next, the disk 7 is rotated by the shaft 1, and the suction port 5A is closed by the plunger 5B. At the same time, the peak 7A of the disk 7 rides on the roller 8, so that the plunger 5B pressurizes the fuel in the cylinder 5D. .

At this time, since the passage 5E in the plunger 5B is closed, the fuel in the cylinder 5D becomes high pressure.

When the passage 5E coincides with the discharge port 5G provided in the wall 5F, the high-pressure fuel passes through the passage 17 and the discharge valve 6 to the fuel injection valve (
(see FIG. 3, 55).

On the other hand, the fuel entering one end 9A of the hydraulic piston 9 from the passage 16 moves the piston 9 to the left against the spring 18 according to the pressure, and the arm 19 that engages at approximately the center of the piston 9 is moved. It rotates clockwise (clockwise) around the center of the roller ring 20.

Therefore, the roller ring 20, which is fixed to the other end of the arm 19 and pivotally supports the roller 8, is similarly rotated clockwise.

As a result, the roller 8 can lift the disk 7, which moves integrally with the rotary plunger 5B, faster by the amount that the roller ring 20 is rotated clockwise, so that the fuel in the cylinder 5D is pressurized faster and is pumped through the discharge valve 6. In other words, the injection timing supplied to the fuel injection valve 55 shown in FIG. 3 is advanced in accordance with the discharge pressure of the low pressure pump 2.

On the other hand, the combustion chamber of the engine has a structure as shown in FIG.
It is compressed while causing

At 10 to 200 degrees (crank angle) before top dead center, fuel is injected from the fuel injection valve 55 for a period of about 20 degrees (crank angle), but this fuel rides on the vortex 54 and turns in the direction of the arrow, causing a glow. It flows in contact with the tip of the plug 56.

The speed of this vortex 54 decreases rapidly as the piston 50 approaches the top dead center.

Further, the glow plug 56 is energized and becomes red-hot at least during cranking (when the scooter motor is driven).

For this reason, when the engine is cold and difficult to start, if the fuel injection timing is advanced (15° to 20° before top dead center), the injected fuel will ride a fast vortex and swirl, causing it to glow red-hot repeatedly. Ignition is ensured by heating with the plug.

Further, during idle operation after startup, the glow plug 56 is not energized, but during the compression stroke of the piston 50, the vortex chamber 53
Because the injected fuel is mixed uniformly by the fast vortex flow inside,
As shown in FIG. 4, a high combustion pressure (solid line) is obtained.

As a result, smooth rotation can be ensured even when the engine is cold, and idling durability can be significantly improved.

Conventionally, the advance of the fuel injection timing when the engine is cold is
The driver manually operated a knob provided on the driver's seat to rotate the cam 10 shown in FIG. 2 and move the hydraulic piston 9 to advance the angle.

Therefore, as long as the driver operates the knob reliably at the time of starting, the angle will be advanced by a predetermined angle according to the amount of tension on the knob, and even when the engine is cold, smooth rotation can be ensured as mentioned above. Idle durability will be significantly improved.

However, if the driver becomes depressed and does not return the knob to its original position even after the engine has warmed up, the engine will continue to be forcibly advanced, and the N in the exhaust gas will continue to be advanced.
This results in problems such as an increase in OX and an increase in combustion noise.

The present invention has been made in view of the conventional problems, and includes a forced angle advance device that advances the angle by a predetermined angle by the driver's operation when the engine is cold, as well as a temperature sensing device that detects the warm-up state of the engine. By providing a device that detects the warm-up state based on the signal from the temperature sensing device and cancels the advance of the forced advance device, the advance operation can be reliably canceled in the warm-up state to prevent an increase in NOx. The purpose is to suppress the increase in combustion noise.

This will be explained below based on the drawings.

FIG. 5 is a diagram showing an embodiment of the present invention.

A retaining sleeve 38 is attached to the nut 4 on the driver's cab panel 41.
3, and a rod 39 having an operating knob 40 attached to one end is slidably fitted into this sleeve 38.

The rod 39 is connected to the injection timing control device 4 via a cable 44.
These components constitute a forced angle advance device.

Note that 22 is a return spring for the arm 11, and 28 is a stopper.

On the other hand, a solenoid 37 for controlling the movement of the rod 39 is attached to the lower part of the holding sleeve 38 of the rod 39.

The solenoid 37 has a plunger 37A that is biased upward by a spring 37B.
The tip of the rod 39 is adapted to engage with a groove 39A formed in the rod 39.

This solenoid 3T serves as a key switch 33 and a temperature switch 3 as a temperature sensing device for detecting the warm-up state of the engine.
6 to the battery 35.

According to the above configuration, when the driver pulls the knob 40 to the right to the position shown in the figure when the engine is cold, the tip of the plunger 37A of the solenoid 37 is turned off by the spring 3 because the temperature switch 36 is turned off.
7B fits into the groove 39A of the rod 38 and is locked.

As a result, the cam 10 rotates, and the piston 9 connected to the advance angle mechanism reliably moves to the advance side by a predetermined amount, thereby performing forced advance.

As a result, starting becomes easier, the idle ring rotates smoothly after starting, and idling durability is significantly improved.

Then, the engine warms up and the temperature switch 36 is turned on (
At this time, the key switch 33 is of course in the on state)
, the solenoid 37 is energized and the plunger 37
The tip of A moves away from the groove 39A of the rod 39, and the lock is released.

Therefore, the knob 40, rod 39, and cable 44 are moved to the left by the return spring 22 to the stopper 28 position, the arm 11 and cam 10 are rotated clockwise as shown by the arrow, and the hydraulic piston 9 is moved upward by the spring 18 in the figure. When pressed, the lead angle is released.

The return spring 22 and stopper 28 that engage the arm 11 are used to ensure the return of the cam 10;
The purpose of this arrangement is to accurately position the arm 11 to prevent rattling caused by vibration of the arm 11 and to prevent the release of harmful exhaust gas and noise after warming up.

Therefore, even after warming up, there is no risk of forced advance, and an increase in NOx and combustion noise can be reliably prevented.

FIG. 6 shows another embodiment.

This embodiment is basically the same as the embodiment shown in FIG. This is what I did.

In this case, the temperature switch 36 is a temperature switch whose characteristics are opposite to those in FIG. At this time, suction restraint is performed, and the above-mentioned effects can be obtained.

As explained above, according to the present invention, in addition to a forced advance device that advances the angle by a predetermined angle by the driver's operation when the engine is cold, a temperature sensing device that detects the warm-up state of the engine, and a temperature sensing device that detects the warm-up state of the engine, Since a device is provided for canceling the advanced angle operation of the forced advance device in response to a signal from the device, the advanced angle can be reliably canceled after warm-up is completed, and an increase in NOx and combustion noise can be reliably prevented.

Further, since it is sufficient to simply add a temperature sensing device and an advance angle release device to the conventional forced advance device, the structure is simple and the reliability of control is improved.

[Brief explanation of drawings]

Figure 1 is a general explanatory diagram of the fuel injection pump, Figure 2 is a sectional view of the advance mechanism shown in Figure 1, Figure 3 is a sectional view of the cylinder head of the engine, and Figure 4 is the fuel injection timing (advance angle). ), FIG. 5, and FIG. 6 are diagrams each showing an embodiment of the present invention. 4... Injection timing control device, 9... Hydraulic piston, 10... Cam, 11... Arm, 36... Temperature switch, 37...
・Solenoid, 39...Rod, 40...
...Knob, 44...Cable, 45...
- Holding iron piece, 46...Holding coil.

Claims (1)

[Scope of Claims] 1. In a diesel engine in which fuel injection timing is controlled by moving a movable member connected to an advance mechanism of a fuel injection pump, the movable member is moved to a certain position by an operation of a driver when the engine is cold. A forced advance device moves the angle to the advance side by a fixed amount, a temperature sensing device detects the warm-up state of the engine, and a signal from the temperature sensing device cancels the advance operation of the forced advance device and causes the forced advance. A fuel injection timing control device for a diesel engine, comprising a device for returning to a normal position that is retarded from the position. 2. The fuel injection pump includes a low-pressure pump driven by an injection pump shaft, a roller that lifts a disk for the high-pressure pump that is driven by the injection pump shaft and slides on the shaft, and a roller ring that supports the shaft of the roller. an arm fixed to; a hydraulic piston that moves the arm in a direction to advance the injection timing in accordance with an increase in the discharge pressure of the low-pressure pump; and a spring that contacts one end of the piston and acts in a direction to retard the injection timing; The diesel engine according to claim 1, wherein the diesel fuel injection pump is a distribution type fuel injection pump comprising a movable member that abuts the other end of the piston and moves the piston in a direction to advance the injection timing. Engine fuel injection timing control device.