JPS6138334B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a device that automatically controls fuel injection timing in a diesel engine in accordance with the operating conditions of the engine.

During combustion in the cylinder of a diesel engine, there is an ignition delay between the start of fuel injection and the start of combustion that should be recognized. In order to maintain a substantially constant and most effective phase at all times, the timing of the start of fuel injection must be adjusted in the advance direction in proportion to the engine speed.

Generally, a fuel injection pump for a diesel engine is provided with a timer piston for adjusting the fuel injection timing, and the discharge pressure of the fuel injection pump is introduced into a pressure chamber formed at one end of the timer piston. By providing a timer spring that presses the timer piston toward the pressure chamber at the other end of the piston, the fuel injection timing relative to the engine speed can be adjusted to a certain speed N when the engine speed is as shown in FIG. It is well known that the rotational speed is constant until the rotational speed N is reached, but once the rotational speed N is exceeded, the angle is advanced in proportion to the rotational speed.

On the other hand, the combustion noise and vibration of a diesel engine are greatly affected by the fuel injection timing, and it is effective to delay the fuel injection timing to reduce combustion noise and vibration. Since N must be set to a value higher than the rotation speed _N0 in the idling operation range so that the rotation speed in the low rotation range is stabilized, the injection timing based on the advance angle characteristics of the timer piston is determined to reduce combustion noise and From a vibration point of view, it is too early in the idling range.

Therefore, Japanese Patent Application Laid-open No. 54-59523 as a prior art discloses that in a fuel injection pump equipped with a timer piston as described above, the fuel injection pump is placed in a second pressure chamber housing a timer spring at the other end of the timer piston. The fuel injection timing is controlled by introducing the discharge pressure at At one end of the timer piston, on the pressure chamber side, there is an electromagnetic solenoid that presses the timer piston in the advance direction when energized. It is proposed to improve the startability of the engine by providing a solenoid and advancing the fuel injection timing by energizing the solenoid when starting the engine.

However, as in this prior art, in the idling operating range of the engine, the injection timing is retarded by adjusting the enlargement of the variable throttle in the discharge pressure introduction passage to the second pressure chamber at the other end of the timer piston. When starting the engine, in order to control the injection timing to the advance side using a solenoid provided at one end of the timer piston, a second pressure chamber housing the timer spring must be formed in a sealed chamber at the other end of the timer piston. In addition, the fuel injection pump has to be provided with two control means, one for operating the timer piston in the retard side and the other in the advance side, making the structure extremely complicated. In addition to this, there is a problem in that the fuel injection pump becomes larger and its weight increases.

The present invention provides a timer piston for controlling the fuel injection timing as shown in FIG.
This problem is solved by using a single electromagnetic solenoid to retard the engine angle in the idling range and to advance the engine when starting the engine.

Therefore, the present invention is provided with a timer piston for adjusting the fuel injection timing for the diesel engine, and introduces fuel discharge pressure into a pressure chamber at one end of the timer piston, while introducing the fuel discharge pressure into a pressure chamber at one end of the timer piston. In a fuel injection pump comprising a timer spring that presses the timer toward the pressure chamber, a portion of the housing housing the timer piston that forms the pressure chamber includes a movable spring that comes into contact with one end surface of the timer piston. An electromagnetic solenoid with an iron core is provided, and an electric circuit connecting the electromagnetic solenoid and a power source includes a movable iron core that moves the timer piston against its timer spring to advance the fuel injection timing when the engine is started. A pressure switch is provided to operate the movable iron core in the direction of retracting from the timer piston in the idling operating range in relation to the intake negative pressure of the engine or the discharge pressure of the fuel injection pump. It has a similar structure.

Hereinafter, the embodiments shown in FIGS. 2 and 3 will be described. In the drawings, 1 is a distribution type fuel injection pump 1 for a diesel engine (not shown);
Inside the main body case 2 are a drive shaft 3 that is rotationally driven at a reduction ratio of 1/2 from the crankshaft of the engine, a plunger barrel 4, and a shaft that rotates and slides within the plunger barrel 4 in relation to the drive shaft 3. A vane-type feed pump 6 provided on the drive shaft 3 supplies the fuel in the fuel tank 7 into the main body case 2 through a sedimentor and a filter, and removes the surplus in the case 2. The fuel returns to the fuel tank 7 from the overflow port 8, and the fuel oil pressure within the main body case 2 increases in proportion to the engine speed.

A disk-shaped cam plate 9 is provided at one end of the pump plunger 5 in the main body case 2, and the cam plate 9 is slidably joined to the drive shaft 3 with a coupling 10, and the same number of cylinders as the cylinders of the engine are provided on the end surface of the cam plate 9. The end face of the cam is pressed by a plunger spring 13 to a roller 12 attached to a cylindrical roller holder 11 that is rotatably attached inside the main body case 2, and is biased by the rotation of the drive shaft 3. Therefore, the pump plunger 5 is the plunger barrel 4.
By rotating and sliding inside the main body case 2, appropriate amounts of fuel in the main body case 2 are sent from the delivery valves 14, 14 to the fuel injection valves (not shown) in each cylinder of the engine.

In FIG. 2, 15 is a spill ring for increasing and decreasing the fuel injection amount by sliding, 16 is a governor mechanism that transmits power to the drive shaft 3 via gears 17 and 18, 19 is an accelerator lever, and 20 is a spill ring. A control linkage mechanism for slidingly controlling the spill ring 15 by a governor mechanism 16 and an accelerator lever 19 is shown.

21 is a timer device;
is a cylindrical timer housing 2 integrally formed on the outer surface of the main body case 2 in a direction perpendicular to the drive shaft 3.
2. Consists of a timer piston 23 slidably inserted into the housing 22 and a timer spring 24 for the timer piston 23. On the other hand, a pressure chamber 26 is provided in the timer housing 22 on the side opposite to the timer spring 24 and communicates with the inside of the main body case 2 through a port 27 provided in the timer piston 23. When the pressure, that is, the fuel oil pressure inside the main body case 2 increases, the timer piston 23 slides against the timer spring 24, thereby controlling the fuel injection timing in advance in accordance with the characteristics shown in FIG. 1. It's becoming like that.

An electromagnetic solenoid 29 having a coil 30 is screwed onto the cover plate 28 attached to the end of the timer housing 22 on the pressure chamber 26 side.
The tip of the movable iron core 31 at 9 is connected to the pressure chamber 26.
The timer piston 23 is inserted into the
The receiving piece 31' that comes into contact with the pressure chamber 2 is fixed.
6 includes a spring 32 stronger than the timer spring 24.
The spacer ring 33 held at When a current flows through the coil 30 in the direction from one terminal 30' to the other terminal 30'', the movable iron core 31 is moved by the spacer ring 33 or the nut 3.
4 is moved backward by an appropriate distance l ₁ so that it comes into contact with the cover plate 28, and conversely, one terminal 3 is removed from the other terminal 30''.
When a current flows in the direction of 0', the movable iron core 31
The nut 34 is configured to protrude by an appropriate distance l ₂ so as to come into contact with the spacer ring 33.

Reference numeral 35 designates a diaphragm-type negative pressure responsive switch, the diaphragm chamber 36 of which is connected via a pressure transmission passage 37 to the downstream side of a throttle valve (not shown) provided in the intake passage of the engine. A piston-shaped switch body 38 made of an insulator connected to the diaphragm chamber 36 is urged into a switch case 40 made of an insulator by a spring 39 in the diaphragm chamber 36, and this switch body 38 has two conductive pieces. 41, 42, and the switch case 40 is provided with four contacts B ₁ , B ₂ , B ₃ , B ₄ and two ground contacts A ₁ , A ₂ , and the switch body 38 is pushed into the switch case 40 . In the first position,
Contact B ₁ connects to fourth contact B ₄ via the other conductive piece 42
In addition, the third contacts B ₃ are connected to the ground contact A ₂ via one of the conductive pieces 41, but the negative pressure inside the diaphragm chamber 36 increases and the switch body 3
8 moves backward inside the switch case 40, the second
Contact B ₂ connects to third contact B ₃ via one conductive piece 41
In addition, the fourth contacts B ₄ are configured to be switched to be connected to the ground contact A ₁ via the other conductive piece 42, respectively.

43 is a key switch having a base contact B connected to the battery 44, a normal operation contact D after engine startup, and a starter contact S, and the normal operation contact D is connected to the second contact surface through a circuit 45.
B ₂ respectively connect the starter contacts S to the first contact B ₁ via a circuit 46, while one terminal 3 in the coil 30 of the electromagnetic solenoid 29
0' is connected to the third contact B ₃ via a circuit 47, and the other terminal 30'' is connected to the fourth contact B ₄ via a circuit 48.

In this configuration, when starting the diesel engine, when the base contact B is connected to the starter contact S at the key switch 43, the starter motor (not shown) is operated, while the electromagnetic solenoid 2
One terminal 30' of the coil 30 of No. 9 is connected to the ground contact A ₂ via the circuit 47, the third contact B ₃ and one conductive piece 41, and the other terminal 30'
0″ has a circuit 48, a fourth contact B ₄ , and the other conductive piece 4
2. A battery 44 is connected via the first contact B ₁ and the circuit 46, and the other terminal 3 is connected to the coil 30.
Current flows from 0'' to one terminal 30',
Since the movable iron core 31 protrudes, the timer piston 23 slides in the advance direction against the timer spring 24, so that the fuel injection timing at the time of starting the engine is determined by the timer device. The set value is advanced to point C shown in FIG. 1, thereby improving the startability of the engine (the amount of advance θ ₂ at this time depends on the distance l ₂ between the spacer ring 33 and the bolt 34).

After the engine is started, the key switch 43 is switched from the base contact B to the normal operation contact D, and the power supply to the coil 30 of the electromagnetic coil 29 is temporarily cut off. The intake negative pressure is high, and this intake negative pressure is applied to the diaphragm chamber 3 of the negative pressure responsive switch 35.
6 to move the switch body 38 backward from the switch case 40 against the spring 39. This connects the other terminal 30'' of the coil 30 of the electromagnetic solenoid 29 to the ground contact A ₁ via the circuit 48, the fourth contact B ₄ and the other conductive piece 42, and connects it to the one terminal 30' of the coil. is circuit 4
7. Third contact B ₃ , one conductive piece 41, second contact
It is connected to the battery 44 side via B ₂ and the circuit 45, and current flows through the coil 30 from one terminal 30' to the other terminal 30'', causing the movable iron core 31 to retreat from the timer piston 23. Therefore, the timer piston 23 moves in the retracting direction by the force of the timer spring 24, so that the fuel injection timing during idling is determined from the setting by the timer device 21 at point E shown in FIG. (The amount of retardation θ ₁ at this time is due to the difference between the spacer ring 33 or the nut 34 and the cover plate 28.
(determined by the spacing dimension l ₁ ).

When the rotation of the engine becomes higher than the rotation during idling, the intake negative pressure becomes smaller and the switch body 38 of the negative pressure response switch 35 is activated by the spring 3.
9, the second contact B ₂ and the third contact B ₃ are disconnected from each other at the switch body 38 made of an insulator, and the electrical connection is broken to the coil 30 of the electromagnetic solenoid 29. Since the energization is cut off, the movable iron core 31 returns the timer piston 23 to its normal position by the spring 32, and from then on, the timer device 21 responds to the increase in fuel oil pressure in the main body case 2, that is, the rotation speed. As it rises, it slides in the advance angle direction, and the fuel injection timing is controlled in accordance with the advance angle characteristics shown in FIG.

In this case, if an oil chamber 50 is formed in the electromagnetic solenoid 29 that communicates with the pressure chamber 26 of the timer through an orifice 49, the oil flowing in and out of the oil chamber 50 through the orifice 49 will cause A tambour effect can be applied to the back and forth movement of the movable iron core 31, and the characteristics C and E in FIG. 1 can also be changed.

In the above embodiment, in a diesel engine equipped with a throttle valve in the intake passage, the fuel injection timing is retarded during idling in response to the intake negative pressure on the F flow side from the throttle valve. In the case of a diesel engine which is not equipped with a throttle valve, the other embodiment shown in FIG. 4 is applicable.

As shown in the drawings, this other embodiment is substantially the same as the previous embodiment, except that a diaphragm type hydraulic response switch 51 and an electromagnetic relay switch 52 are used in place of the negative pressure response switch 35 of the previous embodiment (common parts are indicated by the same symbol).

The hydraulic response switch 51 is attached to the end of the electromagnetic solenoid 29 so that fuel oil from the timer pressure chamber 26 enters the diaphragm chamber 53, and the diaphragm is biased toward the diaphragm chamber 53 by a spring 54. A rod 57 made of an insulator that slides inside a boss 56 made of an insulator is attached to the rod 55, two contacts 58 and 59 are provided to the boss 56, and a conductive piece 60 is provided to the rod 57. When the fuel oil pressure in 26 is lower than the pressure at idling, both contacts 58 and 59 do not conduct electricity, and when the fuel oil pressure reaches the pressure at idling, both contacts 5
8 and 59 are connected by a conductive piece 60, and both contacts 58 and 59 are configured to be disconnected again when the fuel oil pressure becomes higher than the pressure at idling.

Further, the electromagnetic relay switch 52 includes a coil 61, four contacts B ₁ ′, B ₂ ′, B ₃ ′, B ₄ ′, and two ground contacts A ₁ ′, A ₂ ′, and is used for normal operation of the key switch 43. The contact D is connected to one contact 58 of the hydraulic response switch 51 via a circuit 62 and to the coil 61 via a circuit 63, and the other contact 59 of the hydraulic response switch 51 is connected to a second contact B ₂ via a circuit 64. ', the starter contacts S of the key switch 43 are connected to the first contact B1' through the circuit ₆₅ , and one terminal 30' of the coil 30 of the electromagnetic solenoid 29 is connected to the first contact B1'.
is connected to the third contact B ₃ ′ through the circuit 66, and the other terminal 30″ is connected to the fourth contact B ₄ ′ through the circuit 67, while the electromagnetic relay switch 52 , the third contact B ₃ ′ is connected to the ground contact A ₂ ′, and the fourth contact B ₄ ′ is connected to the first contact B _{1 ′} . A fourth contact B ₄ ' is configured to connect to the second contact B ₂ ′ and to the ground contact A ₁ .

Therefore, when the engine is started by the key switch 43, current flows through the coil 30 of the electromagnetic solenoid 29 from the other terminal 30'' to the one terminal 30', causing the movable iron core 31 to protrude and move.
The timer advances the fuel injection period, but
After startup, if the base contact B is connected to the normal operation contact D by the key switch 43, the third contact B ₃ ′ becomes the second contact B ₂ ′, and the fourth contact Contact B ₄ ′ switches to connect to ground contact A ₁ ′, while in idling operation after startup, fuel injection pump 1
The pressure-responsive switch 51 is actuated to connect its contacts 58 and 59 by the fuel oil pressure in the main body case 2, so the coil 30 in the electromagnetic solenoid 29 is connected from one terminal 30' to the other terminal 30''. Current flows in the direction of , the movable iron core 31 moves backward, and the timer retards the fuel injection timing.When the engine speed becomes higher than the idling speed, the hydraulic response switch 51 By cutting off both contacts 58 and 59, the current to the coil 30 in the electromagnetic solenoid 29 is cut off, so the movable iron core 31 is returned to its original position by the spring 32, and the subsequent injection timing is adjusted. , is controlled by a timer device,
The operation is similar to that of the embodiment shown in FIG. 3 above.

As described above, the present invention controls the fuel injection timing, which is controlled by the timer piston as shown in FIG. In this case, since the control to the retard side in the idling operating range and the control to the advance side at the time of starting are performed by one electromagnetic solenoid provided in the fuel injection pump, the above-mentioned prior art The structure is significantly simpler and cheaper than those using separate means, and since the fuel injection pump only needs to be equipped with one electromagnetic solenoid, the fuel injection pump can be made smaller and lighter. This has the effect of making it possible to achieve this goal.

[Brief explanation of the drawing]

Fig. 1 is a diagram showing the advance characteristics of the injection timing by the timer device, Fig. 2 is a longitudinal sectional front view of the distribution type fuel injection pump, and Fig. 3 is an enlarged cross-sectional view taken from - of Fig. 2, which is the first embodiment of the present invention. FIG. 4 is a sectional view similar to FIG. 3, showing another embodiment of the present invention. DESCRIPTION OF SYMBOLS 1... Distribution type fuel injection pump, 2... Main body case, 3... Drive shaft, 4... Plunger barrel, 5... Pump plunger, 9... Cam plate, 12... Roller, 11... Roller holder ,2
1... Timer device, 23... Timer piston, 24... Timer spring, 26... Pressure chamber, 29
...Electromagnetic solenoid, 30...Coil, 31...
Movable iron core, 31'... Receiving piece, 33... Spacer ring, 32... Spring, 35... Negative pressure responsive switch, 37... Pressure transmission passage, 43... Key switch, 51... Hydraulic responsive switch, 52 ...Electromagnetic relay switch.

Claims (1)

[Claims] 1. A timer piston is provided for adjusting the injection timing of fuel to the diesel engine, and the discharge pressure of fuel is introduced into the pressure chamber at one end of the timer piston, and the timer piston is introduced into the pressure chamber at the other end of the timer piston. In a fuel injection pump that is provided with a timer spring that presses the timer piston, a portion of the housing that accommodates the timer piston that forms the pressure chamber includes an electromagnetic core that is provided with a movable iron core that contacts one end surface of the timer piston. A solenoid is provided, and an electric circuit connecting the electromagnetic solenoid and a power source includes a movable iron core that operates the timer piston in the direction of advancing the fuel injection timing against the timer spring when the engine is started. and a pressure switch that operates the movable iron core in the direction of retracting from the timer piston in the idling operating range in relation to the intake negative pressure of the engine or the discharge pressure of the fuel injection pump. A control device for fuel injection timing in diesel engines.