JPS59128967A - Fuel injection pump of diesel engine - Google Patents

Abstract

PURPOSE:To simplify the constitution of both the structure and control system by providing a control cylinder section and restricting the operation of a free piston based on simple open/close actions of one solenoid valve. CONSTITUTION:During a discharge stroke, a control circuit 30 maintains the opened condition of a solenoid valve 22 during a suction stroke until a stroke position Sp is attained, thereby the fuel compressed in a pressure chamber 16 during this time is released to the low-pressure side, therefore no high pressure is applied to the primary pressure chamber 12, and a free piston 11 is not operated. As the discharge stroke proceeds, the control circuit 30 deenergizes the solenoid valve 22 to close it, and a passage (f) is closed and the pressure chamber 16 is pressurized, then this high pressure is applied to the primary pressure chamber 12 and the free piston 11 is moved to the left. Accordingly, the fuel in secondary pressure chamber 13 is compressed, and a check valve 20 is pushed open and fuel is injected and fed to the predetermined cylinder.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a fuel injection pump for a diesel engine,
More specifically, the present invention relates to a distributed fuel injection pump capable of electronically controlling fuel injection amount or injection timing.

As a fuel injection pump that can be electronically controlled, the control sleeve of the distribution type fuel injection pump is controlled by position servo control to control the fuel injection lid, and the oil pressure to the hydraulic timer is adjusted by duty control to adjust the injection timing. There are known devices that control (for example, 5AE8
00167 etc.).

However, in such a fuel injection pump,
In order to accurately control the position of the control sleeve, a servo actuator with extremely high cylinder accuracy is required, and on the other hand, the control system is difficult because this actuator moves the solenoid valve that controls the injection timing. Overall, there was a tendency for the structure to become more complex.

The present invention aims to eliminate such a deadening point by providing a plunger pump that rotates in synchronization with the rotation of an engine and reciprocates slowly, and a primary pressure chamber and a feed that communicate with the pressure chamber of this plunger pump. A control cylinder portion defining a secondary pressure chamber in front and behind the free piston, which communicates with a fuel passage from the pump and a distribution boat of the planter, and a solenoid valve that opens the primary pressure chamber or the plunger pressure chamber to the low pressure side. By regulating the suction and discharge actions of the piston associated with the operation of the plunger pump based on the opening and closing of the solenoid valve, the amount of fuel sucked into the secondary pressure chamber and the timing of discharge of the fuel can be controlled. That is, the present invention provides a fuel injection pump in which the amount of fuel injection and the timing of injection are controlled.

Hereinafter, the present invention will be explained based on illustrated embodiments.

In FIG. 1, l is a plunger pump consisting of a plunger 2 and a plunger barrel 4 formed in a pump body 3 so that the plunger 2 is slidably fitted therein.

The plunger 2 is fixed to an eccentric disk 5, and is connected to a drive shaft 6 that rotates in synchronization with the engine via a spline-shaped joint (not shown).

The eccentric disk 5 is always urged to the left in the figure by a spring 8 interposed between a thrust bearing 7 located on the back side thereof and the pump body 3.

The eccentric disc 5 has the same number of seven-eighth cams 9 as the engine cylinders, and the spring 8 is attached to a roller 10 that is rotatably supported at a predetermined portion of the main body 3.
It rotates over this roller 10 while being in elastic contact with the urging force of.

Therefore, each time the plunger 2 rotates, the plunger barrel 4 is reciprocated in the axial direction by a predetermined cam lift.

On the other hand, a free piston 1 that can freely slide is attached to the pump body 3.
A control cylinder section 14 defining a primary pressure chamber 12 and a secondary pressure chamber 13 is provided before and after the control cylinder section 1 .

In this case, the free piston 11 has a pressure receiving area on the primary pressure chamber 12 side (80 is larger than the pressure receiving area (A2) on the secondary pressure chamber 13 side).
A large stone 5 is also formed in a stepped shape, and a primary pressure chamber 12 is formed.
The spring 150 inserted therein is always biased toward the secondary pressure chamber 13 by its elasticity.

The primary pressure chamber 12 of the control cylinder section 14 communicates with the pressure chamber 16 of the plunger pump 1 via a passage a, and also
The secondary pressure chamber 13 is connected to the annular groove 17 of the plunger 2 through a passage.
Communicate at all times.

The grand gloss 2 includes a passage C consisting of a passage part penetrating the annular m17 in the radial direction and a passage part bored in the axial direction from the pressure chamber 16 side so as to intersect with the passage part, and further, A distribution boat 18 communicating with the annular groove 17 is formed facing the sliding surface with the barrel 4. Note that a pole 19 is press-fitted to close the opening of the passage C facing the pressure chamber 16.

The barrel 4 or the pump body 3 has a rotating column "OL" which is connected to the distribution port 1 each time the plunger 2 moves during the discharge stroke.
A plurality of distribution passages d (only one is shown in the figure) corresponding to the number of engine cylinders are formed radially around the plunger 2 so as to sequentially communicate with the plunger 8 . The plurality of division arrays 119
d are Fyli fixed cylinder injectors (not shown)
A check valve 20 (or a delivery valve valve) is interposed in the middle to prevent backflow of fuel from the insoector side.

Furthermore, a fuel passage e is formed in the barrel 4 or the pump body 3 to introduce fuel from a feed pump (not shown) so as to constantly communicate with the plunger annular waste 17.
A check valve 21 is interposed in the middle of this passage to prevent the fuel from flowing back toward the feed pump.

By the way, in the present invention, a solenoid valve is provided to open the primary pressure chamber or plunger pressure chamber of the control cylinder portion to the low pressure side, but in this embodiment, the primary pressure chamber 12 and the pressure chamber 16 are connected as shown in the figure. A solenoid valve 22 is interposed in the middle of a passage f formed to communicate the passage a and the fuel passage e from the feed pump, and by opening the passage f, the secondary pressure chamber 12 is moved to the low pressure side, in this case. It is opened to the feed pump discharge pressure (assumed to be Pa).

The solenoid valve 22 includes a poppet-shaped valve body 23 that opens and closes the passage f from the primary pressure ¥12 side, and a solenoid granger 24 connected to the valve body 23, each of which closes based on the elasticity of coil springs 25 and 26. When the solenoid coil 27 is energized, the spring 25
．． 26, the plunger 24 and the sixth valve body 23 open the valve by seven strokes.

As will be described later, when the plunger pump 1 enters the discharge stroke with the solenoid valve 22 closed, the pressure chamber 16
Since the pressure acts on the primary pressure chamber 12 of the control Schilling (14), the free piston 11 moves to the left and enters the secondary pressure chamber 13.
of fuel is pumped toward the injector, but since it is necessary to always keep the position of the free piston 11 constant at the end of this injection operation, in this embodiment, the free piston 11 is at a certain stroke position. 1
(At this point, a spill boat 28 and a spill passage g are provided which communicate the primary pressure chamber 13 with the low pressure side, in this case passages f and e-\.

Furthermore, according to the above equation, the fuel injection amount and the injection time change depending on the relationship between the suction and discharge action of the plant pump L and the opening/closing timing of the solenoid valve 22.
Specifically, the injection amount increases as the timing from entering the suction stroke until opening the solenoid valve 22 is delayed, and the injection timing becomes later as the timing from entering the discharge stroke until closing is delayed. - Appropriate values for force, fuel injection amount, and injection timing are determined in advance according to the engine operating state represented by various conditions such as cooling water temperature, rotation speed, accelerator opening, and starting conditions, so the stroke position of plant gear 2 is determined in advance. If this is detected, it is possible to open and close the solenoid valve 22 at a predetermined timing using this as a reference, and control the fuel injection amount and injection timing in accordance with the actual operating conditions.

Therefore, in this embodiment, as a means for performing the above control operation, a rotation sensor 29 that detects the rotational position of the bong shaft 60 is used as a guide, and a signal from the sensor 29 is used as a guide at a timing corresponding to the engine operating state at that time. Solenoid valve 2
A control circuit 30 for driving the opening and closing of the switch 2 is commonly used.

The rotation sensor 29 is a well-known sensor consisting of an encoder disk 31 that rotates together with the pump shaft 6, and a pickup 32 that provides rotation angle pulses of the pump shaft 6 and the plantar 2 to the control circuit 30 as the disk 31 rotates. In this case, in addition to the angle pulse for each unit angle, the planter 2 is configured to generate a reference pulse, for example, when starting the suction stroke. In other words, the rotational position of the plunger 20 is detected by counting the number of angular pulses from the reference pulse, and the stroke amount Sp of the plunger 2 is determined by the face cam 9 of the eccentric disc 5 depending on the rotational position of the pump shaft 6. Since the lift given by the
p can be known accurately.

The control circuit 30 thus detects the stroke amount sp based on the pulse signal from the rotation sensor 29, and applies it to the solenoid valve 22 according to the engine operating conditions obtained through various sensors (not shown). The timing of the opening/closing signal (on or off current) is determined, for example, by table lookup, and the solenoid valve 22 is driven based on this. Note that the control value corresponding to the timing is stored in advance in the form of a memory table or the like so that an appropriate fuel injection amount and injection timing can be obtained depending on the engine operating state.

Next, the operation of the fuel injection pump under the operation of such a control system will be explained with reference to FIG.

First, the suction stroke of the plunger pump 1 will be explained. The suction stroke starts from the point where the seven-eighth cam 9 of the eccentric disc 5 passes through the maximum lift portion according to the rotation of the pump shaft 6, and the reference pulse from the rotation sensor 29 at this moment Based on the input, the control circuit 30 starts counting the angle pulses anew and keeps the solenoid valve 22 closed until the plunger stroke amount Sp determined by the current operating state is reached.

With the solenoid valve 22 closed, the plunger pump l enters the suction stroke (the plunger 2 moves to the left in the figure).
At this time, the decrease in pressure P due to the expansion of the pressure chamber 16 is directly transmitted to the primary pressure chamber 12 of the control cylinder section 14, so that the free piston 11 is moved by the spring 15.
It moves to the right against the pressure and expands the secondary pressure chamber 13.

Therefore, an amount of fuel corresponding to the stroke amount Sf of the free piston 11 opens the check valve 21 and is sucked into the secondary pressure chamber 13 via the fuel passage e, the plunger annular groove 17, and the passage S.

However, when the plunger stroke amount Sp reaches a predetermined amount determined by the control circuit 30, the solenoid valve 22 is energized and the passage f is opened.
6 communicates with the fuel passage e, which is on the low pressure side, and fuel from the passage e is introduced into the pressure chamber 16, which continues to expand, so that the suction operation wb of the free piston 11 is stopped.

As is clear from this, the amount of fuel sucked into the secondary pressure chamber 13 (injected fuel t) depends on the long period from when the plunger pump l enters the suction stroke until the solenoid valve 22 opens. Therefore, the amount of fuel injection can be controlled by the opening timing of the solenoid valve 22.

Note that when the solenoid valve 22 is in an open state, the free piston 11 is urged toward the secondary pressure chamber 13 by the tension F of the coil spring 5, but the The distribution port 18 communicated through the annular groove 17 is closed during the suction stroke, and the check valve 21 prevents Q backflow to the fuel passage e, which also communicates through the annular groove 17, so that the secondary pressure The chamber 13 remains sealed, so that the free piston 11 remains in the position it was in when the solenoid valve 22 was open.

Next, to explain the discharge stroke, the discharge stroke starts when the suction stroke ends and the next face cam 9 of the eccentric disk 5 rides on the roller 10.
This causes the plunger 2 to move to the right and begin to compress the pressure chamber 16, but the open side 1 circuit 30 maintains the open state of the solenoid valve 22 during the suction stroke until it reaches the predetermined stroke position Sp. During this time, the fuel 4-) compressed in the pressure chamber 16 is released to the low pressure side through the passages a and f, and therefore, the free piston 11 does not operate because high pressure does not act on the primary pressure chamber 12.

[1] When the discharge stroke progresses and is delayed to a predetermined time determined by the operating state at that time, the control circuit 30 detects this based on the count of pulse No. 1δ from the rotation sensor 29 and sends a signal to the solenoid valve 22. Since the energization is stopped and the valve is closed, the passage f is closed and the pressure chamber 16 becomes high pressure, and the primary pressure chamber 12 receives this high pressure and the free piston 11 moves to the left.

Therefore, the fuel in the secondary pressure chamber 13 is compressed by the prepressure and flows through the passage C to the distribution port 18, and further to the distribution passage d which was facing the distribution port 18 at this time, and flows through the check valve 2.
0 is pushed open and injected into a predetermined cylinder. In addition, the pressure P of the secondary pressure chamber 13 at this time, =AL P, 10'
Adashi, Haba free piston A, A.

A.

When the discharge operation of the free piston 11 progresses and its stroke lid Sf increases to a certain extent, the plunger compression pressure P is increased by the area ratio of 1 at both ends of the piston 11, the primary pressure chamber 12 communicates with the spill port 28, and the subsequent blunt compression Since the pressure PI is released to the low pressure side through the passages g and f, the operation of the free piston 11 is stopped and the fuel injection is completed.

Each time the plunger 2 rotates once, the suction stroke and the discharge stroke are repeated by the number of face cams 9 of the eccentric disk 5 and by the number of engine cylinders, thereby sequentially supplying fuel to each cylinder. Ru.

By the way, if we look closely at the action of the plunger pump 1 and the closing timing of the solenoid valve 22 during the discharge stroke, it can be seen that the longer the period from entering the discharge stroke until the solenoid valve 22 closes, the later the injection start timing becomes. . Therefore, the fuel injection timing can be controlled by the closing timing of the solenoid valve 22. In total, the fuel injection amount and injection timing can be controlled by one opening/closing operation of the solenoid valve 22 per cycle of the plunger pump 1. It is possible.

As described above, according to the present invention, a control cylinder part is provided which injects fuel in response to the plant pump, and the operation of the free piston is regulated based on the simple opening and closing operation of one solenoid valve. As a result, it is possible to control multiple fuel injection amounts and injection timings, which not only simplifies the construction of the structure and control system of the distribution type injection pump, but also improves the accuracy of the fuel injection pump. It is possible to achieve seclusion.

1' of 1'? 6. Simple Congratulations The first figure is a sectional view of a practical example of the present invention, and the second figure is an explanatory diagram showing the operation of the main part thereof.

1...Plunger barrel, 2...Plunger barrel, 3
... Pump body, 4... Plunger barrel, 5...
・Eccentric disc, 6...Pump shaft, 11
...Free piston, 12...Primary pressure amount, 13...
・Secondary exit, 14...control cylinder +l15.16・
...Pressure chamber, 18...Natsu [! 1[.

Claims (1)

[Claims] A planter that rotates and reciprocates in synchronization with engine rotation, a planter barrel into which the planter is slidably fitted, and a distributor formed radially in the barrel so as to open facing the distribution boat of the planter. a control cylinder section defining a passage, a primary pressure chamber communicating with the Plantsja pressure chamber, a fuel passage from the feed pump, and a secondary royal chamber communicating with the distribution boat before and after the free piston;
A diesel engine fuel injection pump characterized by being equipped with a check valve that prevents fuel from flowing backward from the secondary pressure chamber to the feed pump side, and a solenoid valve that opens the primary pressure chamber or plunger pressure chamber to the low pressure side. .