JPH02233861A - Fuel injection pump - Google Patents

Abstract

PURPOSE:To stop an engine positively in preventing any reinjection from occurring by enlarging an opening area of a pore in an overflow valve, and installing another pore different from this pore in the overflow valve in addition. CONSTITUTION:An overflow valve 60 for preventing pressure in a pump case from exceeding an upper limit area of pressure limits is attached to a pump housing 4. In this overflow valve 60, there are provided with a hole 61 interconnected to the pump case 12, a pore 62 interconnected each to this hole 61 and another pore 63 sufficiently larger in diameter than the pore 62. Thus, when the supply of fuel to a plunger chamber 24 is stopped by a solenoid valve 32, any reinjection is prevented from occurring and an engine can be positively stopped.

Description

Detailed Description of the Invention (Industrial Icheon Field) The present invention provides a fuel injection pump for use in a diesel engine;
In particular, it relates to a fuel + (t-injection pump) equipped with a solenoid valve for stopping the engine by stopping the supply of fuel from the pump chamber to the plunger chamber.

(Prior Art) Conventional fuel injection pumps include, for example, an oil feed pump that is driven by an engine to forcefully deliver fuel to a pump chamber in a pump housing, and an oil feed pump that is driven by an engine to forcefully deliver fuel to a pump chamber in a pump housing. A pressure regulating valve that controls the pressure in the pump chamber by adjusting the pressure, an overflow valve that releases excess fuel in the pump chamber to the low pressure side through a pore, and a suction passage that leads fuel in the pump chamber to the plunger chamber. The solenoid valve is normally open so that the fuel in the pump chamber is supplied to the plunger chamber, and when it is closed, it closes the suction passage and supplies the fuel to the plunger chamber. It is known that the engine is stopped by stopping the fuel supply.

Furthermore, such conventional fuel injection pumps are generally provided with a timer that controls the injection timing according to the pressure within the pump chamber. This timer is provided with a two-stage advance characteristic as shown by the broken line A in FIG. Advance angle control is started when 1 stage advance angle control Δ. and the pump rotation speed is N4.
Advance angle 1 has a large advance rate in the medium and high rotation range from N to N.
, 'J 61Δ.

In order to give the timer such a two-stage advance angle characteristic,
It is necessary for the pressure regulating valve to have pressure characteristics as shown by the broken line B in FIG. In other words, this pressure characteristic indicates that in an extremely low rotation range where the pump rotation speed increases from N, (for example 100 rpm) to a predetermined extremely low rotation speed N, (for example 300 rpm), the pressure inside the pump chamber decreases. , the pressure I) is 1, and the pump rotation speed is N. 11i when reached
The predetermined pressure 1) is sufficiently high to start the advance angle control Δ1.
(Curve section B in Fig. 3), and the pump rotation speed increases to N. In the low rotation range from P8 to P4, the pressure inside the pump chamber increases from P8 to P. The pump rotation speed is increased to N, {
Near N. In the middle and high rotation range until it rises to the vicinity,
The pressure inside the pump chamber is increased from 1) to 1)4 at a large 1L increase rate (straight line section 13 in the figure).

(Problem to be Solved by the Invention) However, the above-mentioned conventional fuel injection pump including the electromagnetic valve n;1 has a timer having a two-stage advance characteristic and I) a pressure characteristic. When a pressure regulating valve is used, and 1) an overflow valve 401 having a pore 400 with a diameter of about 0.55 mm as shown in FIG. Since the fuel in the room escapes to the fuel tank through only one small diameter pore 400, the amount of fuel escaping is small, so the extremely low rotation range (N, ~ N,
), the pressure inside the pump chamber increases. Therefore,
In the extremely low speed range, even if the solenoid valve 1) is closed to stop the engine and the suction passage 1) is closed, the fuel in the pump chamber will flow into the cut-off boat of the plunger that opens into the pump chamber. There is a problem in that the fuel flows into the plunger chamber through the vertical hole, and as a result, the fuel that has flowed in is re-injected from the injection nozzle and the engine does not stop.

The present invention has been made by focusing on such conventional problems, and in order to start advance angle control by a timer when the pump rotation speed reaches a predetermined low rotation speed, the pump rotation speed is increased. Even if the pressure regulating valve has a pressure characteristic that rapidly increases the pressure in the pump chamber to a predetermined pressure before reaching a predetermined extremely low rotation speed, the pressure in the pump chamber can be kept low in the extremely low rotation speed range. It is therefore an object of the present invention to provide a fuel injection pump that can prevent re-injection and reliably stop an engine when the supply of fuel to a plunger chamber is stopped by a solenoid valve.

(Means for Solving the Problem) In order to achieve the above object, a fuel injection pump for a wood power plant includes an oil feed pump that is driven by an engine and pressure-feeds fuel to a pump chamber in a pump housing, and A pressure regulating valve that controls the pressure in the pump chamber by adjusting the fuel Jl1 supplied from the oil pump to the pump chamber, an overflow valve that releases excess fuel in the pump chamber to the low pressure side through pores, and The pressure regulating valve is equipped with a solenoid valve that closes the suction passage that leads fuel to the plunger chamber, thereby stopping the engine. In the fuel injection pump, the opening area of the pore of the overflow valve is increased, or a pore other than the pore is used to rapidly increase the pressure of the overflow valve to a predetermined pressure. It is installed on the valve.

(Function) In the fuel injection pump described in Section 2, the amount of fuel in the pump chamber that escapes to the low pressure side through the overflow valve increases.

Therefore, in the extremely low rotation range until the pump rotation speed reaches a predetermined extremely low rotation speed, the amount of fuel pumped from the oil feed pump is small, so the amount of fuel escaping to the low pressure side through the overflow valve increases, causing the pump to The pressure inside the room can be kept low.

In the rotation range higher than the predetermined extremely low rotation speed, the amount of fuel pumped from the feed pump increases as the pump rotation speed increases, so the amount of fuel that escapes to the low pressure side through the overflow valve increases. The drop in pressure inside the pump chamber due to this is small.

(Example) Hereinafter, one embodiment of the present invention will be described based on the drawings.

FIG. 1 is a diagram showing a fuel injection pump according to an embodiment, and this fuel injection pump 1 uses a mechanical governor 2 to control the injection amount and a timer 3 to control the injection timing. I! This is a mechanical distribution type fuel injection pump that does not use a magnetic valve.

In addition, in FIG. 2, the timer 3 and the oil supply pump 6, which will be described later, are shown at a 90° angle with respect to other members for ease of understanding.
It is shown in different cross-sections.

In the center of the pump housing 4 of the fuel injection pump l,
A drive shaft 5 is arranged. The end of this drive shaft 5 is
It protrudes to the outside of the pump housing 4 and receives driving torque from an internal combustion engine (not shown). An oil pump 6 is connected to the drive shaft 5 . This fuel pump 6 transports the fuel in the fuel tank 7 to a pipe 8 and a fuel filter 9.
and the suction 1-1 side (low pressure side) 6a via the suction passage 10.
At the same time, the sucked fuel is pressurized, and the pressurized fuel is discharged into the pump chamber 12 in the pump housing 4 through the discharge passage II. A fuel return passage 13 is formed between the discharge passage 1l and the suction passage IO for returning fuel from the discharge 1'l 6b of the fuel pump 6 to the suction 121 side 6a. Inside, the pressure inside the pump chamber 12; lj
A pressure regulating valve 14 is installed to control the pressure.

1); A plunger I6 is slidably inserted into the plunger barrel 15 which is mounted on the pump housing 4. A cam disk 17 is fixed to the base end of the plunger 16, and the cam disk 17 is connected to the end of the drive shaft 5 via a coupling 18 so as to be movable in the axial direction. In addition, the cam disk l7 has a cam surface having a number of cams 111 corresponding to the number of parts! 7a is formed. The cam 17a is pressed against a roller 20 held by a roller holder 19 by a plunger spring 2I, so that the plunger l
6 is designed to reciprocate by the same number of cam ridges during one rotation by the drive +l1+5.

At the tip of the plunger l6, during the suction stroke while the plunger l6 moves back to the left in the figure, the fuel in the pump chamber 12 is transferred to the pump housing 4 and the plunger barrel l5.
The same number of suction grooves 25 are provided at equal intervals in the circumferential direction for introducing the fuel into the plunger chamber 24 via the fuel passages 22 and suction bows 1 and 23 formed in the fuel passages 22 and 23, respectively. branja 1
In the center of 6, one end opens to the plunger chamber 24 [1]
A vertical hole 27 is formed at the other end of which can communicate with the pump chamber l2 via a cut-off boat 26. In the middle of this vertical hole 27, fuel pressurized in the plunger chamber 24 is delivered to the plunger barrel l5 at equal intervals in the circumferential direction during the pressurization and pressure feeding stroke while the plunger 16 moves rightward in the figure. A distribution boat 29 leading to one of the distribution passages 28 provided in the same number
is formed. The fuel passing through each distribution passage 28 is forced to be sent to an injection valve (not shown) via a distribution passage 30 of the pump housing 4, a delivery valve 31 attached to the pump housing 4, and an injection pipe (not shown). ing.

11; j A solenoid valve 32 for opening and closing the fuel intake passage 22 is attached to the pump housing 4. This solenoid valve 3
2 is always open? ! ! A magnetic valve opens the fuel suction passage 22 when the current is not energized, allowing the fuel in the pump chamber 12 to flow into the plunger chamber 24.
When energized, the passage 22 is closed to stop the supply of fuel ↑1 to the plunger chamber 24, thereby stopping the engine.

A control sleeve 33 is slidably fitted into the shaft portion of the plunger 1G where the cut-off port 26 is located. Cutoff boat 26 is control sleeve 3
When the fuel in the plunger chamber 24 flows out into the pump chamber 12 through the vertical hole 27 and the cut-off boat 26, the delivery valve 3 opens into the pump chamber 12.
Pressure delivery of fuel to l has stopped. After 11 seconds, the injection ends. By adjusting the axial position of the control sleeve 33 on the plunger l6 by the mechanical governor 2, the amount of fuel to be injected is adjusted.

At the bottom of the pump housing 4, a timer 3 is marked with a serial number (j). A timer piston 38 is provided which slides within the cylinder 37 due to the balance with the spring force of a timer spring 36 interposed in a low pressure chamber 35 communicating with the suction L: l 6 a side. , when the pressure in the high pressure chamber 34 overcomes the spring force of the timer spring 36 and the timer piston 38 is displaced to the left in the figure, the timer piston 3
The roller holder 1 is connected to the roller holder 8 via a rod 39.
9 rotates, whereby the phase of the reciprocating movement of the plunger 16 with respect to the rotation of the drive shaft 5 is shifted in the advance direction, and the injection timing is controlled in the advance direction.

In addition, in the timer 3 of this embodiment, the pump rotation speed of the oil feed pump 6 is set to a predetermined low rotation speed N, according to the characteristics of the engine.
(See Figure 3), the spring constant of the timer spring 36 is set so that the timer screw 1/n 38 begins to displace to the left from the position shown in the figure, and advance control of the injection timing begins. has been done.

11; In order to give the timer 3 the above-mentioned two-stage advance characteristic as shown by the broken line 8 in FIG. If only pore 6l is provided, the third
It has the above-mentioned pressure characteristics as shown by the broken line B in the figure.

That is, this pressure regulating valve 14 has one end connected to the discharge passage 1.
A cylinder 40 is formed in the pump housing 4 with one end opened at 1 and the other end closed, a piston 4l slidably fitted into the cylinder 40, and the piston 4l shown in the lower part of the figure. The inner wall of the cylinder 40 is provided with a spring 42 for returning the fuel pumped from the oil feed pump 6 to the suction 1 side 6a of the oil feed pump 6 via the fuel return passage 13 and the suction passage 10. An opening 43 is formed in the opening 43. When the piston 4l is displaced upward in the figure due to an increase in fuel pressure according to the pump rotational speed of the oil supply pump 6, the opening 43 is opened [1 area changes, and the opening L1
By changing the claw that escapes to the fuel return passage 13 through the portion 43, the pressure characteristics described in "U" can be obtained.

In addition, as shown in FIGS. 1 and 2, by releasing excess fuel in the pump chamber 12 to the low pressure side, the pump chamber 12
An overflow valve 60 is attached to the pump housing 4 to prevent the internal pressure from exceeding the upper pressure limit range.

This overflow valve 60 has a hole 61 that communicates with the pump chamber l2 and a diameter of 0.5 that communicates with the hole 6l.
A pore 62 with a diameter of about 5 mm and a pore 63 with a diameter sufficiently larger than the pore 62 are provided.

The overflow valve 60 includes a pipe 44 for guiding fuel passing through the pore 62 to the fuel tank 7, and a pore 63.
A pipe 45 for guiding the fuel passing through the pipe 8 to the downstream side of the fuel filter 9 is connected to each pipe 45 .

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

Excess fuel in the pump chamber 12 is returned to the fuel tank 7 through the pore 62 of the overflow 1 valve 60 and the pipe 44, and is also returned to the fuel tank 7 through the pore 63, the pipes 45, 8, and the suction passage l.
The oil is returned to the suction port 6a side of the oil feed pump 6 through O. Therefore, the leakage of fuel from the pump chamber 12 to the fuel tank 7 and the suction day 6a side, which are the low pressure side, is increased compared to the conventional example in which only the pores 62 are provided.

By the way, as described above, if the overflow valve 60 is provided with only the 011 pore 62 in the pressure regulating valve l4 as in the conventional example, the pressure regulating valve l4 will have the same shape as shown by the broken line B in FIG. It has the above pressure characteristics. However, in the above embodiment, as mentioned above, the amount of fuel escaping from the pump chamber l2 to the low pressure side is increased by −1 compared to the conventional example, so the pressure inside the pump chamber 12 is reduced to the solid line B in FIG. It changes as shown by ′.

That is, the pump rotation speed is N, (for example, l O OrpI
! l) to a predetermined extremely low rotational speed N, (e.g. 30 O
In the extremely low rotation range (up to 200 rpm), the amount of fuel pumped from the oil pump 6 is small, so the pressure inside the pump chamber 12 increases due to the increase in the amount of fuel escaping to the low pressure side through the overflow valve 60. can be kept low (straight line portion B1' shown by the solid line in FIG. 3).

The pump rotation speed is from N to N. In the low rotation range until the rotation speed increases, the amount of fuel pumped from the oil feed pump 6 increases as the pump rotation speed increases. The drop in pressure within chamber 12 is small. Therefore, in this low rotation range, the pressure in the pump chamber l2 is lower than the pressure in the straight section 13 shown by the broken line in the figure. (the straight line portion 13,' shown by the solid line in the figure).

The pump rotation speed is from around N4 to N. In the middle and high rotation range until the rotation speed increases, the amount of fuel pumped from the oil feed pump 6 further increases as the pump rotation speed increases, so the amount of fuel escaping to the low pressure side through the overflow valve 60 increases. The drop in pressure within the pump chamber 12 due to the increase is small. Therefore, in the high rotation range, the pressure in the pump chamber I2 changes slightly lower than that in the straight line section 13 indicated by the broken line in the figure (straight line section B.' indicated by the solid line in the figure).

In this way, since the pressure in the pump chamber I2 is kept low in the extremely low rotation range, is it possible to stop the engine? [
When the fuel suction passage 22 is closed by energizing the magnetic tube 32, the fuel in the pump chamber 12 flows through the cut-off boat 26 and the vertical hole 27 that are open to the pump chamber 12. does not flow into the plunger chamber 24. Therefore,
The supply of fuel into plunger chamber 2/I is completely stopped, re-injection is prevented, and the engine is reliably stopped.

In the above embodiment, since the pressure inside the pump chamber 12 changes as shown by the solid line B' in FIG. The two-step advance angle characteristic shown by the solid line A' in the figure is slightly different from the angle characteristic.

In addition, in the above embodiment, in order to prevent a shortage of fuel on the suction port 6a side of the oil supply pump 6 due to an increase in the amount of fuel escaping from the overflow valve 60 to the low pressure side, a narrow pipe with a large diameter is used. The fuel escaping from the hole 63 is transferred to the pipe 4
5, 8 and the suction passage 10 to return to the suction D 6 a side. At this time, since the fuel escaping from the pores 63 is guided to the downstream side of the fuel filter 9 of the pipe 8, the life of the fuel filter 9 is not impaired.

In the first embodiment, the overflow valve 60 has a small diameter pore 62 and a larger diameter pore 6.
By providing two pores 62 and 63, the amount of fuel escaping from the overflow valve 60 to the low pressure side is increased.
Two pores may be provided in the overflow valve 60.

(Effects of the Invention) As described in detail below, the fuel injection pump according to the present invention includes an oil feed pump that is driven by an engine and pressure-feeds fuel to a pump chamber in a pump housing; a pressure regulating valve that controls the pressure in the pump chamber by regulating the amount of fuel co-supplied from the pump chamber to the pump chamber; an overflow valve that releases excess fuel in the pump chamber to the low pressure side through pores; The 01I pressure regulating valve is equipped with a solenoid valve that stops the engine by closing the suction passage that leads fuel to the plunger chamber. In a fuel injection pump having a characteristic of rapidly increasing the pressure of The structure provided in the overflow valve increases the amount of fuel in the pump chamber that escapes to the low pressure side through the overflow valve. Therefore, in order to start advance angle control by the timer when the pump rotation speed reaches a predetermined low rotation speed,
4. Until the pump rotation speed reaches a predetermined extremely low rotation speed. Even if the pressure regulating valve has a pressure characteristic that rapidly increases the pressure in the pump chamber to a predetermined pressure, the pressure in the pump chamber can be kept low in the low rotation range, and this allows the fuel supply to the plunger chamber to be controlled by electromagnetic control. When stopped by the valve,
The engine can be reliably stopped by preventing the occurrence of re-injection.

[Brief explanation of the drawing]

fJSl to FIG. 3 show one embodiment of the present invention, and the first
The figures are a cross-sectional view showing a fuel injection pump according to an embodiment of the present invention, FIG. 2 is a cross-sectional view showing an overflow valve, and FIG.
The figure is a graph simultaneously showing the relationship between the pump rotation speed and the pressure inside the pump chamber, and the relationship between the pump rotation speed and the advance angle amount.
The figure is a sectional view showing a conventional overflow valve. 1...Fuel pump, 4...Pump housing,
6... Oil pump, 6a... Suction 1] (low pressure side),
7...Fuel ↑1 tank (low pressure side), l2...pump chamber, I4...pressure regulating valve, 32...electromagnetic valve, 60...overflow valve, 62.63...pore.

Claims (1)

[Claims] 1. an oil pump driven by an engine to forcefully feed fuel to a pump chamber in a pump housing; a pressure regulating valve that controls the pressure in the pump chamber by adjusting the amount of fuel supplied from the oil pump to the pump chamber; The pressure regulating valve includes an overflow valve that releases excess fuel in the pump chamber to the low pressure side through a pore, and a solenoid valve that stops the engine by closing a suction passage that leads the fuel in the pump chamber to the plunger chamber. In the fuel injection pump, the pressure in the pump chamber is rapidly increased to a predetermined pressure by the time the engine starts and the oil feed pump reaches a predetermined extremely low rotational speed. A fuel injection pump characterized in that the opening area of the pore is increased or a pore other than the pore is provided in the overflow valve.