JPS5874836A - Distribution type fuel injection pump - Google Patents

Abstract

PURPOSE:To expand the controllable range of fuel injection time by using an electromagnetic spool valve as a control valve to be provided in the escape path of the operating pressure chamber of a timer piston for regulating the reciprocal moving time of the plunger of the distribution type fuel injection pump. CONSTITUTION:A distribution type fuel injection pump is provided with a timer piston 28 to regulate the reciprocal moving time of a plunger by means of a face cam pressingly touched through a cam roller 15 by a ring 25 when turning a roller ring 25 in the circumferential direction through a pin 26. In this case, an escape path 301 leading the operating pressure chamber 30 of the timer piston to the housing chamber 302 of the spring 45 is formed, and an electromagnetic spool valve 307 is provided midway on the escape path 301. The spool valve 307 is housed in a sleeve 304 having an orifice 305 and a spill port 306, always energized toward the closed direction by the spring 309, and opened when supplying electricity to a solenoid 39, whereby opening the escape path 301.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a distributed fuel injection system, and particularly to a control mechanism for controlling fuel injection timing.

The distributed fuel injection 4 pumps used to send fuel to each cylinder of a fuel injection multi-cylinder engine require full adjustment of the fuel injection timing depending on the engine rotational speed. It was configured as shown in the figure.

That is, J is a ring main body, and two pressure fuel chambers are configured inside. Fuel at a predetermined pressure is fed into this pressure fuel chamber 2 from an oil feed pump 3. For oil supply 4:yf8, a vane pump driven by a pump camshaft (not shown) is used to suck up fuel from the fuel tank 4 and send it into the pressure fuel chamber 2. The pressure fuel chamber 2 is connected to the fuel tank 4 by a return passage 5, and in the middle of the return passage 5 there are provided a valve 6, for example, a mail-type over-valve 7a, which opens at a set pressure, and a throttle 1.

A housing 10 is attached to the pump body IK, and a granger 1 is inserted into the housing IOK so as to be rotatable and reciprocating. The f ranger 11 is connected to a drive shaft 12 that rotates in synchronization with the engine.

Gran Tsuya 11 is equipped with face cam 14',
This #7 eighth cam 14 is in rolling contact with the cam roller 15, and the granger 11 is moved by the #7 eighth cam 14.
During rotation, it is reciprocated a number of times depending on the number of cylinders in the engine. When the granger 1 during each reciprocating movement is in the suction stroke in which it is moved to the left in FIG. Fuel is sucked from the pressure fuel chamber 2 through one of the ninth suction grooves 17 and a suction hole 18 extending inside the housing 10 . Then, as the plunger 11 rotates, the suction hole 18 is closed, and at the same time, the compression stroke in which the f2 plunger 1 moves to the right in FIG. Data hole 20 and Granja 1
The fuel is supplied to a discharge port 22 through one distribution groove 21 provided on the outer peripheral surface of the fuel cell 1, and is sent through the discharge port 22 to a fuel injection valve of a corresponding cylinder (not shown). ''; The spill ring 23 provided with a freely fingerable pressure on the Ip plunger 11 opens a radial discharge hole 24 which communicates with the vertical hole 24t during the compression stroke of the grand gloss 11, and this discharge hole 24t.
- The amount of fuel injection supplied from the discharge port 22 is determined by the opening timing. That is, when the discharge hole 24 is opened, the fuel in the pump pressure feeding chamber 16 is returned to the pressure fuel chamber 2. The spill ring 23 is controlled to move in the left-right direction in FIG. 1 depending on the engine speed and the amount of accelerator pedal depression.

However, the cam low that is in contact with the 7-eighth cam 14 is
) 15 is rotatably supported by a roller ring 25. A pin 26 is connected to the low ring 25, and the pin 26 is attached to a timer piston 28 via a mail 27. The timer piston 28 is slidably fitted into a cylinder z9 formed by a four-pump main body IK, and the axial direction of the timer piston 28 is disposed 7 at right angles to the axial direction of the plunger 11. An operating pressure *SO is formed on one end surface of the timer piston 28, and this operating pressure chamber 30 is formed inside the timer piston 28 and communicates with the pressure fuel chamber 2 via a good introduction passage 31f, and is connected to the pressure fuel chamber 2 through the pressure fuel chamber 2. High pressure fuel in chamber 2 is introduced. Note that the introduction path 31 is provided with an orifice 5it- to delay pressure propagation. The operating pressure chamber 30 can be formed outside the pump body 1 and has a relief passage 5.
It communicates with the fuel tank 4 via st-. This escape route 3
3, an oriice member S4 and a seat valve 36 as a control valve are provided. The seat valve 35 is 1)
Since the needle portion 37 is pressed against the seat portion 38 by the fi-in spring 31fK, the relief passage 33t is closed, and the opening operation of the seat valve 35 is performed by the solenoid 39. The solenoid 39 operates based on a command signal from an electronic control device 40, which detects the engine load sensor 4, which detects the engine load, and the position sound of the timer piston 28. Based on the signal from the position sensor 42, the command signal to the solenoid 39 is automatically controlled.

The position sensor 42 changes the magnetic field of a coil 44 by means of an iron core 43 connected to the timer piston 28, and detects changes in electrical signals at this time. The other end surface of the timer piston 28 is pressed by a spring 45 and is always urged toward the operating pressure chamber 3 degrees.

In the distributor fuel injection system having such a configuration, the fuel in the pressure fuel chamber 2 is introduced into the working pressure chamber 3o, so the timer piston 2I is set to the second position according to the fuel pressure in the working pressure chamber 3o.
Moved to the left of the diagram. The fuel pressure PA in the pressure fuel chamber 2 is [as shown in FIG. are doing)
increases as shown in Kg. When the engine speed increases further and drops to the opening pressure of the overflow valve 6, the overflow valve 6 is opened, so that even if the engine speed N increases thereafter, the pressure PA remains constant as shown in Figure 4. .

The fuel pressure PA in the pressure fuel chamber 2 is transmitted to the operating pressure chamber 3o of the tie 1 piston 28, so based on this fuel pressure PA, the timer piston 28 moves to the left in FIG.
Only that portion is moved against the pressing force of the spring 45. The tie 1 piston 28 is moved by rotating the roller ring 25t clockwise in FIG. 2 via the pin 26. Therefore, the cam roller 15 is advanced by the amount of rotation of the roller ring 25, so that the reciprocating movement of the granger 11 during one revolution is performed through the seven-eighth cam 14tP with an advanced angle. As a result, the injection timing of the fuel supplied from the discharge port 22 is advanced.

By the way, when the seat valve 35 provided with the relief passage 33 connected to the working pressure chamber 30 is opened by the operation of the solenoid 39 based on the command signal from the electronic control unit 40, the fuel in the working pressure chamber 3a is released through the relief passage S3. Returned to tank 4. As a result, the fuel pressure within the working pressure chamber 30 is reduced, and the timer piston 28 is returned to the right in FIG.
Therefore, the fuel injection timing can be retarded. In this way, the opening/closing time ratio of the relief passage 33, that is, the solenoid 3
By controlling the on-off time ratio of 9 with the electronic control circuit 40, the duty ratio in the entire rotation range of the engine is controlled in relation to the fuel pressure pB of the working pressure chamber 3o, as shown in FIG. It is something that can be done.

However, in the conventional device shown in FIGS. 1 and 2, the relief passage 33 is opened and closed by the seat valve 35, and therefore has the same problems as the Ti. That is, seat valve 3
5 is the high fuel pressure pB transmitted from the working pressure chamber 30
is supported by the needle part 37 to maintain its oil-tightness.
must be set large. Therefore, the seat valve is 35F! Due to the large set load of the return spring 36, the response to the solenoid 39 is poor, resulting in characteristics as shown by the broken line C in FIG. In this characteristic C, the range d in particular is an uncontrollable region due to the large set load of the return spring 36, and as a result, the controllable range of fuel injection timing is narrow and highly accurate control cannot be performed. Met.

Further, the seat valve 35 includes a seat portion 38 and a knee Yk portion 37.
Leaks may occur if the machining is not performed with high precision, but these high precision machinings have the drawback of being extremely troublesome and time-consuming.

Furthermore, the above-mentioned conventional 4 has a relief passage 33 and a seat valve 35.
Since it is formed outside the I-imp main body 1, there is a problem that the number of piping parts increases and the number of assembly steps becomes large.

The present invention has been made based on the above-mentioned circumstances, and has an object of providing a distributed fuel injection tank that has excellent responsiveness to a solenoid, expands the controllable range of fuel injection timing, and can be assembled easily. do.

In other words, the present invention uses an electromagnetic spool valve as a control valve provided in the relief path of the operating pressure chamber of the timer piston, thereby eliminating problems in operating characteristics caused by the set load of the return spring, and preventing stuttering and the timing of fuel injection. The controllable range has been expanded, and the escape passage is formed inside the cylinder member that houses the timer piston, thereby realizing a reduction in the number of parts.

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

FIG. 3 shows only the parts related to the present invention, and the other structures are the same as the conventional example shown in FIGS. 1 and 2, so illustrations are omitted, and the same parts are given the same symbols The explanation will also be omitted.

In FIG. 3, reference numeral 301 denotes a relief passage whose one end communicates with the operating pressure chamber 30 and whose other end communicates with the accommodation chamber 3o2 of the spring 45. This relief passage 301 is formed by drilling in the I-ring main body 1. ing. In this embodiment, the cylinder 29 is formed directly in the pump body 1, so the relief passage 301 is also formed in the cylinder body 1. However, if the cylinder 29f is formed separately from the pump body 1, the relief passage 301 is formed separately from the pump body 1. The passage 801 is preferably provided in the cylinder component. The spring housing chamber 302 is communicated with the fuel tank 4 via a discharge passage 303.

A sleeve S04 is fitted into the I-ring main body 1,
This sleeve 304 is provided with an orifice 305 communicating with the upstream side of the above-mentioned escape passage 301 and a spill port 306 communicating with the downstream side of the above-mentioned escape passage 301, facing each other. A spool valve 307 as a control valve is slidably inserted into the sleeve 304. An annular groove 308 is formed in the spool valve 301, and when the spool valve soy is moved downward from the illustration, the orifice 305 and the spill port 10 are connected to each other via the annular groove 308.
6 are made conductive to each other. The spool valve Jar is always pressed upward in the drawing by the return spring 30#, and when the solenoid JI9 is energized, it is attracted by the solenoid 39 against the return spool ring 30#.

According to the spool valve 301 as described above, the solenoid 3
9, the spool valve 307 is pressed to the top dead center shown in the figure by the return spring 309, and in this position, the annular groove son does not conduct the Orice SOS and the spill port 106, so there is no leakage. Path 3011d is closed. In this state, no matter how the fuel pressure pB within the pressure working chamber 30 changes, this fuel pressure pB will not move the spool valve 307 against the return spring 309. Therefore, the set load of the return spring 309 can be set to be extremely small.

When a signal is applied to the solenoid J9, the spool valve 307 is moved downward against the return spring j'Off by the electromagnetic attraction force of the solenoid S9. In this case, since the set load of return spooling 30# is small, spool valve S01 has extremely good responsiveness to solenoid 3#. Based on the downward movement of the spool valve S01, the annular 11130B forms the orifice 305 and the spill/-)
3176@ When conductive, the fuel in the pressure working chamber 30 is discharged to the sgelling storage chamber 302 via the relief passage 301 and returned to the fuel tank 4 via the discharge passage 3.03f. Since the fuel pressure pB in the pressure working chamber 30 decreases, the timer piston 28 is returned to its original position.

Therefore, according to this embodiment, if the opening/closing time ratio of the relief passage 30, that is, the opening/closing operating time ratio of the spool valve 307 is controlled through the solenoid 39Yt, the fuel pressure pB in the pressure operating chamber 30 and the duty ratio are controlled over the entire engine rotation range. Figure 5 shows the relationship between the ratios! This means that the pressure pB can be controlled arbitrarily within the required pressure range shown by diagonal lines in FIG. 4. Therefore, the occurrence of the uncontrollable region d is eliminated, and highly accurate control becomes possible, allowing precise control of the fuel injection timing.

Further, since it is only necessary to process the annular groove 308 of the spool valve 301, manufacturing is facilitated, and since the relief passage SOI is formed inside the pong body 1, the number of parts is reduced and assembly is facilitated.

As detailed above, in the present invention, the spool valve is used as the control valve that opens and closes the relief path connected to the working pressure chamber of the timer piston, so the receiving position of the fuel pressure transmitted from the working pressure chamber affects the operating direction of the spool valve. Therefore, the total set load of the return spring of the spool valve can be reduced, the response to the solenoid can be increased, and the required pressure can be controlled with high precision. Therefore, the advance and retard angle of the plunger by the 7-eighth cam can be controlled with high precision via the timer piston, so that the fuel injection timing can also be controlled with high precision. In addition, the spool valve is easy to process, and since the relief passage is formed in the cylinder component, the number of parts is reduced, making manufacturing easier.

[Brief explanation of drawings]

1 and 2 show a conventional distributed fuel injection pump, FIG. 1 is a sectional view, FIG. 2 is a sectional view taken along 1-INK in FIG. 1, and FIG. 3 is an embodiment of the present invention. A sectional view corresponding to FIG. 2 showing an example, and FIGS. 4 and 5 are characteristic diagrams for explaining the operation. 1...Pump body, 10...Housing, 11...
・Plunger, 14...Face cam, 15...Cam roller, 16...Dengue pressure feeding chamber, 22...Discharge port, 25...Roller ring, 26...Bin, 28...
・Timer piston, 29... Cylinder, 30... Working pressure chamber, 31... Fuel introduction di, 301... Relief path, 305... Orifice, 301... Spool valve, J9... Solenoid, 40...Electronic control device. Applicant's agent Patent attorney Suzue Takehiko I Figure 3 to 4 Figure 5

Claims (1)

[Claims] A rotatably driven granger tube is inserted into a housing forming a four-ring pressure feeding chamber, a seven-eighth cam is provided on this plunger, and a roller ring that supports a cam four roller that rolls into contact with the face cam is connected to a timer piston. By applying fuel pressure to the timer piston and causing it to reciprocate, the roller ring is rotationally displaced to adjust the timing of the reciprocating movement of the plunger, and based on the reciprocating movement of the plunger, the fuel in the pump pressure-feeding chamber is forcefully injected. An operating pressure chamber that applies fuel pressure to the timer piston communicates with a fuel introduction passage and a relief passage, and when the relief passage is opened and closed by a control valve, fuel is injected under pressure from the pump feeding chamber. In the distribution type fuel injection pump that controls timing noise, the high-pressure fuel relief passage is formed inside the syringe member constituting the working pressure chamber, and an oriice is provided in the relief passage and a control valve is provided to open and close the relief passage. , is a distributed fuel injection system consisting of nine electromagnetic spool valves.