JPH0259292B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an injection timing adjustment device for a distributed fuel injection pump.

Among the conventionally known distribution type fuel injection pumps and injection timing adjustment devices, a so-called hydraulic timer will be described with reference to FIGS. 1 to 3.

FIG. 1 shows the main part of a conventionally known distribution type fuel injection pump, FIG. 2 shows the main part of its hydraulic timer, and FIG. 3 shows a fuel pump and a hydraulic pressure generator.

In Fig. 1, 1 is a drive shaft, 2 is a surface cam having the same number of cams 2a as the number of engine cylinders, 3 is a roller that rolls on the surface cam 2, 4 is a roller shaft forming the axis of the roller 3, and 5 is a surface cam that has the same number of cams 2a as the number of engine cylinders. A roller holder supporting the roller shaft 4, 6 a plunger fixed to the surface cam 2 and reciprocating and rotating, 6a an oil supply notch, 6b a discharge notch, 6c an oil drain hole, 6d a passage connecting these, 7
8 is a plunger chamber, 8 is a barrel in which the plunger 6 slides, 9 is a spring that presses the surface cam 2 against the roller 3, 10 is an oil supply passage, 11 is a discharge passage, 1
2 is a discharge valve, 13 is a control sleep and plunger 6
is slidably fitted into the oil drain hole 6 of the plunger 6.
When c meets the end surface of control sleeve 13, fuel passage 6d is opened and fuel injection is completed.
14 shows a part of the pump housing;
Reference numeral 15 indicates an oil reservoir chamber of a fuel injection pump surrounded by the pump housing 14, reference numeral 16 indicates a fuel pump shown in FIG. 3, and reference numeral 17 indicates a gear for driving a governor weight (not shown).

FIG. 2 shows a hydraulic timer, 1 being a drive shaft, 3 a roller, 4 a roller shaft, 5 a roller holder, and 18 a timer piston which is slidably fitted into the piston housing 14. A hydraulic chamber 20 is composed of a timer piston 18 and a piston housing 19, and communicates with the oil sump chamber 15 through an orifice 21 bored in the timer piston 18. A timer spring 22 urges the timer piston 18 toward the hydraulic chamber 20. timer piston 1
8 and the roller holder 5 are rotated around the drive shaft 1, and the timing changes.

In FIG. 3, a vane-type fuel pump 16 sucks out fuel from the fuel tank 31 and sends it to the oil sump chamber 15 of the fuel injection pump. A pressure regulating valve 24 is inserted into the discharge side of the fuel pump 16, and overflowing fuel is returned to the suction side of the fuel pump 16.

Next, the functions of the above-mentioned distribution type fuel injection pump and hydraulic timer will be explained.

In FIG. 1, when the drive shaft 1 is driven by the engine, the cam plate 2 rotates, and the plunger 6 fixed to the cam plate 2 is driven as a unit. The cam plate 2 has the same number of cams 2a as the number of engine cylinders, and rotates on a roller 3 fixed to a roller holder 5 via a roller shaft 4, thereby reciprocating by a prescribed cam lift. That is, each time the cam 2a of the cam plate 2 rides on the roller 3, the plunger 6, which is integrated with the cam, moves up (moves to the right) within the barrel 8 by the cam lift, and when the roller 3 comes to the valley of the cam plate 2, The plunger 6 is lowered (moved to the left) by the cam lift due to the biasing force of the plunger spring 9.

To refuel the plunger chamber 7, when the plunger 6 is in its downward stroke, the oil sump chamber 15 of the fuel injection pump, the refueling passage 10, and the refueling notch 6a of the same number as the number of cylinders of the engine at the tip of the plunger 6 are aligned. , the fuel is in the plunger chamber 7 and the plunger passage 6.
d is inhaled. Next, the rotation of the plunger 6 closes the oil supply passage 6, and the discharge notch 6b of the plunger 6 is aligned with one of the discharge passages 11, the number of which is the same as the number of engine cylinders. Thereafter, when the cam 2a begins to ride on the roller 3, the plunger 6 enters an upward stroke, the fuel pressure in the plunger chamber 7 increases, and the fuel is sent through the discharge valve 12 to a nozzle (not shown) of the engine cylinder. When the plunger 6 is further raised (moved to the right) by the cam plate 2,
When the oil drain hole 6c of the plunger 6 meets the end surface of the control sleeve 13, the fuel passage 6d is opened, and the high-pressure fuel inside the plunger 6 is pushed back into the oil sump chamber 15 through the oil drain hole 6c, and fuel injection ends. Therefore, the discharge amount of the fuel injection pump can be controlled by moving the control sleeve 13 left and right. Note that the governor and the control sleeve 13 are connected so as to be interlocked.

Next, the operation of the timer will be described with reference to FIG. The oil sump chamber 15 is filled with oil from the oil supply pump 16,
This communicates with the hydraulic chamber 20 via an orifice 21. The timer piston 18 is pushed to the left by the oil pressure in the hydraulic chamber 20, but since the timer piston 18 is urged to the right by the timer spring 22, the timer piston 18 is pushed to the right at a position where the hydraulic pressure and the urging force are balanced. stands still. The movement of the timer piston 18 rotates the roller holder 5 via the drive rod 23 and shifts the position of the roller 3. Therefore, the timing at which the cam 2a rides on the roller 3 described in FIG. 1 changes, and the injection timing changes. When the oil pressure in the oil pressure chamber 20 increases, the timer piston 18 moves to the left, rotates the roller holder 5 in a direction opposite to the rotational direction of the drive shaft, and advances the injection timing. Since the orifice 21 is still provided in the communication path from the oil sump chamber 15 to the timer hydraulic chamber 20, the timer piston 18 is prevented from moving even if a momentary torque reaction force is applied from the cam 2a to the roller 3 during injection. It's getting old.

Next, as shown in Fig. 3, the amount of fuel required to operate the engine increases as the load and rotation speed increase, but since the discharge capacity of the fuel pump 16 is set to be quite large, the discharge pressure of the fuel pump 16 is The pressure increases with the rotational speed, and the relationship between the rotational speed and the discharge pressure can be arbitrarily set using the pressure regulating valve 24.

As described above, when the engine reaches high rotation speed, the injection pump (Fig. 1), the hydraulic timer (Fig. 2), and the hydraulic pressure generator (Fig. 3)
6 increases, the oil pressure in the timer hydraulic chamber 20 increases next to the pressure in the oil sump chamber 15 of the fuel injection pump, and the timer piston 18 moves the roller 3 to the drive shaft 1.
It rotates in the opposite direction to the rotational direction of the engine and acts to advance the injection timing, so it covers the injection delay and ignition delay that increase as the engine speeds up, and achieves good combustion over the entire rotation speed range. It is becoming possible to do this.

The above effects are sufficient during steady operation, but when the engine accelerates, the combustion chamber wall temperature is lower than during steady operation, and in turbocharged engines, the intake air temperature and pressure are low due to the time delay in the exhaust turbine system. As a result, the ignition delay becomes excessive, resulting in problems such as worsening fuel efficiency and an increase in harmful emissions in the exhaust gas.

SUMMARY OF THE INVENTION An object of the present invention is to provide an injection timing adjustment device for a distribution type fuel pump that advances the fuel injection timing particularly during sudden acceleration, thereby improving fuel efficiency and reducing harmful exhaust gases.

An embodiment of the present invention will be described below based on the accompanying drawings.

In Fig. 4, 1 is the drive shaft of the fuel injection pump, 3 is the roller, 4 is the roller shaft, 5 is the roller holder, 18 is the timer piston, 20a is the first hydraulic chamber, 21 is the orifice, 22 is the timer spring, and 23 is the These drive rods are exactly like conventional hydraulic timers. The piston housing 19' has a cylinder added to the right side of the conventional piston housing 19, and a check valve 26 that allows flow only in the direction of arrow A is installed in the hydraulic chamber 20a, and is pressed by a spring 27.

40 is a rotating shaft that is directly connected to the engine rotating shaft or is driven by increasing or decreasing the speed, and the flyweight 38 is the fulcrum 3
It is attached via 9. 33 is a driving piston. The drive piston 33 is slidably and oil-tightly enclosed in the cylinder 34. The drive piston 33 and the cylinder 34 constitute a second hydraulic chamber 35, and the second hydraulic chamber 35 is connected to the timer piston housing 19' through an oil passage 36 and communicates with the first hydraulic chamber 20a of the timer piston 18. are doing.

Of these systems newly established in the present invention, the second hydraulic chamber 35, oil passage 36, first hydraulic chamber, and 20a are filled with hydraulic oil, and when the hydraulic oil decreases due to leakage, it is replenished through the oil supply hole 37. Ru.

Next, the operation of the above embodiment will be explained.

When the engine accelerates and the engine speed increases,
The speed of the rotating shaft 40 is also increased, and the flyweight 38 attached to it increases the centrifugal force, opening outward and driving the drive piston 3 driven via the fulcrum 39.
3 is pushed to the right, and the pressure in the second hydraulic chamber 35 increases.

When the engine accelerates rapidly, the centrifugal force of the flyweight increases rapidly, and the pressure generated in the second hydraulic chamber 35 also increases. Therefore, a large amount of hydraulic oil from the oil passage 36 pushes open the check valve 26 and is sent into the first hydraulic chamber 20a of the timer piston, and the pressure increases due to the effect of the throttle 21. Therefore, the timer piston 18 is pushed to the left, and the roller 3 is rotated in the opposite direction to the rotational direction of the drive shaft, so that the injection timing is advanced.

When the acceleration is slow, the increase in the centrifugal force of the flyweight 38 is small, so the movement of the drive piston 33 is also slow, and the pressure rise in the first hydraulic chamber 20a of the timer piston is slow, causing the piston to leak due to oil leakage from the throttle 21. 18 does not move and is not advanced.

As mentioned above, the injection timing adjustment device for a distributed fuel pump according to the present invention is configured to adjust the final hydraulic pressure of the drive piston and cylinder, which are driven by the flyweight linked to the engine rotating shaft and discharge hydraulic fluid during acceleration, and the conventional timer. Since the chamber is communicated with the oil passage through an oil passage with a check valve inserted in the passage, the action of the orifice of the first timer piston automatically advances the fuel injection timing, especially when the engine is suddenly accelerating, thereby reducing fuel consumption. improvement and reduction of harmful exhaust gases. Furthermore, since the check valve is interposed in the circuit, the operation of the timer is stabilized and the durability of the device can be increased.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view of the main parts of a conventionally known distribution type fuel injection pump, FIG. 2 is an explanatory diagram of the main parts of a timer for the well-known fuel injection pump, and FIG. 3 is a circuit diagram of a fuel pump.
FIG. 4 is an explanatory diagram of an injection timing adjustment device for a distribution type fuel pump according to the present invention. 15... Oil sump chamber (of fuel injection pump), 18
...Timer piston, 20a...First hydraulic chamber, 2
1... Orifice, 26... Check valve, 33... Drive piston, 35... Second hydraulic chamber, 38... Fly weight.

Claims (1)

[Claims] 1 In an injection timing adjustment device that changes the injection timing by moving the timer piston 18 using the oil pressure in the first hydraulic chamber 20a that communicates with the oil sump chamber 15 of the fuel injection pump via the orifice 21, the device communicates with the rotating shaft 40 of the engine. A drive piston 33 that is driven by a flyweight 38 and discharges hydraulic oil during acceleration, a second hydraulic chamber 35 facing the discharge end of the drive piston 33, and a first hydraulic chamber 20a facing the timer piston 18. 36, and a check valve 26 at the entrance of the first hydraulic chamber 20a that allows oil to flow only from the second hydraulic chamber 35 toward the first hydraulic chamber 20a. Timing adjustment device.