JPH03213655A - Fuel injection pump for internal combustion engine - Google Patents

Abstract

PURPOSE: To speedily and certainly perform stop of an internal combustion engine by forming a load reduction passage containing radial hole communicating with a vertical hole connected with a fuel distribution groove, which is provided for a given position of a pump piston partitioning a pump working chamber whose volume expands or shrinks. CONSTITUTION: A distribution-type fuel injection pump, in which a pump piston 14 is engaged into a cylinder hole 13 of a pump cylinder 12, pressurizes fluid sucked into a pump working chamber 15 through a suction chamber 18 and passage 17 with rotation and reciprocating movements of this pump piston 14, and then distributes and supplies the fluid to each injection valve 44 via a vertical hole 4 and a distribution groove 42. In this case, two radial holes 48 communicating with the vertical holes 40 are formed in the pump piston 14, and annular grooves 50 are formed in the pump cylinder 12 axially spaced from this holes 48 and communicated with the suction chamber 18. Thus, a load reduction passage is formed, and process for opening and controlling the passage is set to be larger than tolerant maximum pump piston process until delivery finish.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The invention relates to a fuel injection pump for internal combustion engines.

Prior Art This type of fuel injection pump is disclosed in, for example, West German Patent No. 2503.
No. 345.

In isolation valves, which are generally designed as electromagnetically operated seat valves,
A valve member, which in the de-energized state closes the suction passage and interrupts the connection between the suction chamber and the pump working chamber, is pressed by a closing spring onto a valve seat formed in the suction chamber. By operating the ignition key to start the internal combustion engine, the isolation valve is energized and the valve member is lifted from the valve seat, opening the suction passage. When the ignition key is turned into its starting position to stop the internal combustion engine, the shutoff valve is activated and the suction duct is closed. In this state, the pump piston no longer draws fuel into the pump working chamber and delivers it to the injection valve, and the internal combustion engine stops.

Under certain conditions, when the pump working chamber and the suction chamber are connected by one suction slit of the pump piston during the continuation of the remaining delivery stroke, the valve body, which is brought into the closed position, is free from the pump working chamber. Loaded by pressure impulses. This pressure shock lifts the valve member from the valve seat,
A refilling process of the pump working chamber takes place via the suction channel for a short time. This amount of fuel flowing into the pump working chamber during the next discharge stroke of the pump piston is calculated as follows: rb Ichiban Kyoumon 1-) #rRgalf- It does not stop and continues to drive.

In many cases, this shutoff valve is also used as an emergency stop device in the event of an injection control malfunction that leads to a runaway of the internal combustion engine. However, in the event of a pressure shock of this type, the manual or automatic control of this shut-off valve may not be able to completely and reliably stop the internal combustion engine.

Problems that the invention aims to solve An object of the present invention is to eliminate the above-mentioned disadvantages.

Means for Solving the Problems The gist of the present invention that solves the above problems is as set forth in claim 1.

Effects of the Present Invention According to the present invention, the pump working chamber is controlled to open even when the suction passage is shut off by the shutoff valve, and this control is performed even when the pump working chamber is at a position delayed in its stroke curve with respect to the rotational position of the pump piston. Suction slot provided on the pump piston
This is done by connecting to the @nk path by 7 ports. As a result, the pressure in the pump working chamber is lost, so that when the suction channel is connected to the pump working chamber, there is no longer sufficient pressure in the pump working chamber to shock the isolation valve. At the same time, after the shut-off valve is closed, the amount of fuel present in the pump work chamber is relieved via the load relief channel, so that further operation of the internal combustion engine is no longer possible. Therefore, the premise is satisfied that the isolation valve can be used as an emergency stop device when the internal combustion engine runs at high speed due to problems with the injection control or when the internal combustion engine has to be stopped for other reasons.

The features of the other claims are advantageous developments of the invention.

In an advantageous embodiment of the invention, the opening of the load relief channel upon reaching a predetermined stroke is controlled in such a way that the pump piston and the pump cylinder are provided with two mutually cooperating load relief openings;
One of the relief openings is connected to the pump work chamber and the other relief opening is connected to the relief chamber, preferably a fuel-filled suction chamber of the fuel injection pump. The two load relief openings are arranged opposite each other in the stroke direction of the pump piston, so that they communicate with each other during a given stroke.

Embodiment The fuel injection pump shown in cross section in FIG. 1 is of the distribution type for a four-cylinder internal combustion engine, and its pump casing 11
A pump cylinder 12 is inserted therein, and a pump piston 14 is rotated and reciprocated within the cylinder hole 13 by a drive shaft 24 and a cam transmission 23 as shown by the arrows. The pump piston 14 delimits a pump working chamber 15 in the cylinder bore 13 on its end face, into which the pump can be fed via a suction slot 16 which serves as a filling groove starting from the end face of the pump piston 14. The piston 14 is filled with fuel during its suction stroke. As can be seen in FIG. 2, the suction slits 16 are distributed circumferentially on the outer circumferential surface of the pump piston 14 with uniform angular spacing.

Corresponding to a four-cylinder internal combustion engine, four intake slots 16 are provided for the intake strokes of the pump piston 14, each of which takes place four times per revolution. During the suction stroke of the pump piston 14 , in each case one suction slit 16 is connected to one of the suction channels 17 opening laterally into the cylinder bore 13 , that is to say to a pump suction chamber 18 provided in the pump housing 11 . connected to one of the suction passages. Fuel is supplied to the pump suction chamber 18 from a fuel tank 20 by a fuel discharge pump 19 . The fuel in the pump suction chamber 18 is under a speed-dependent pressure, which pressure is additionally regulated by a pressure control valve 21 .

The end of the pump piston 14 facing away from the pump working chamber 15 projects into the pump suction chamber 18 and is coupled there by a cam gear 23 to a drive shaft 24 mounted in the pump casing. connected. This cam transmission device 23 includes a roller ring 26 that supports a roller 25, and this roller ring is rotatably supported within the pump casing by a predetermined angle. An end cam plate 27 is fixed to the pump piston 14, and the end cam plate 27 is rotated by being pressed onto a roller 25 by an axial spring force on the surface provided with the end cam. In that case, the number of end cams 28 is equal to the number of suction slits 16 of the pump piston 14.
corresponds to the number of A pawl clutch 29 is provided in the inner bore of the roller ring 26, in which case a pawl 30 on the drive side connected to the drive shaft 24 is adapted to perform a stroke movement while the pump piston 14 rotates independently of the drive shaft 24. It is engaged and connected to a driven-side pawl 31 provided on the pump piston 14 so that the pump piston 14 can perform the following operations. The roller ring 26 is non-rotatably connected to an injection adjustment piston 33 of an injection adjustment device 34 via an adjustment pin 32 . The injection regulator is shown unfolded 90 degrees for illustrative purposes. roller ring 2
This injection adjustment piston, which is axially adjustable tangentially to 6, is loaded in one adjustment direction by a return spring 35 and in the other adjustment direction by the injection adjustment piston 33.
0 is loaded by the pressure in the control chamber 36. As the pressure in the control chamber 36 increases, the injection regulating piston 33 moves against the action of the return spring 35 and moves towards the a-cylinder 26.
As a result, the end cam 2 of the end cam plate 27
8 is engaged with the roller 25 in the direction of advancing the injection with respect to the rotational position of the pump piston 14 or the drive shaft 24, whereby the stroke start of the pump piston 14 and the start of fuel discharge are caused to occur at the rotational position of the drive shaft 24 or the pump piston 14. will be held early. The stroke curve carried out by the pump piston 14 as a function of its angle of rotation α is shown in FIG. The dashed curve shows the travel curve at the early position. In the late position of the stroke curve, the injection regulating piston 33 of the injection regulating device 34 occupies approximately the basic position shown in FIG. In FIG. 3, the rotation angle α is designated, at which angle the suction suction 1-16 establishes a connection between the suction channel 17 and the pump working chamber 17. The symbol ○T represents the top dead center of the pump piston 14, and the symbol UT represents its bottom dead center.

A control sleeve 17 for controlling the injection quantity is arranged axially movably in the pump suction chamber 18 on the pump piston 14, and is controlled by a known type of governor, not shown here. The lever 38 is actuated in a known manner and the outlet of the transverse bore 39 of the pump piston 14 is opened and closed. The transverse bore 39 is connected to a vertical bore 40 of the pump piston 14, which is formed in the end face of the pump piston 14 delimiting the pump working chamber 15 and ends as a blind bore. A radial bore 41 branches off from this vertical bore 40 and communicates with a distribution groove 42 provided on the outer circumferential surface of the pump piston I4. At the height of this distribution groove 42, four pressure conduits 43 open in the cylinder hole 13 of the pump cylinder 12 and are shifted by the same rotation angle, and each pressure conduit is connected to an injection valve 44. . FIG. 1 shows four pressure conduits and one pressure conduit 43 and one injector 44 of the four injection valves.
only shown.

As already mentioned, during each suction stroke, the pump piston 14 sucks fuel from the pump suction chamber 18 via the suction slit 6 which coincides with the suction passage 17, so that the pump working chamber 15 absorbs fuel during the subsequent discharge of the pump piston 14. It is filled with fuel at the beginning of the stroke. The beginning of the delivery stroke is defined by the closing of the pump working chamber 15 due to the interruption of the suction sleeve 16 from the opening of the suction channel 17 by the pump piston 14 . The control sleeve 37 closes the outlet of the transverse hole 39, so that
The fuel present in the pump working chamber 15 is loaded with high pressure and becomes vertically 7AAn%n-#whiteWmrKQ'.
A')G 1. is supplied to one of the pressure conduits and the corresponding injection valve 44. The discharge stroke of the pump piston is
After the pump piston 14 has carried out the delivery stroke defined by the control sleeve 37, this ends by opening the transverse bore from the control sleeve. As a result, the pump working chamber 15 communicates with the pump suction chamber 18 via the vertical hole 40 and the horizontal hole 39, thereby reducing the load. In this state, the discharge pressure of the pump piston 14 is lower than the opening pressure of the injection valve 44, and high-pressure injection is interrupted.

The internal combustion engine stops when the high-pressure injection ends.

For this purpose, a magnetic valve 45 designed as a seat valve is arranged in the suction duct, the valve member 46 of which is inserted into a valve seat 45 formed in the suction duct 17 when the magnet of the magnetic valve 45 is not energized. It is overwhelmingly impressive. The magnetic valve 45 is energized by the introduction of the ignition, which causes the valve member 46 to be lifted off the valve seat 47 and into the suction passage 17.
to open. The magnet valve 45 is energized due to internal combustion. If the internal combustion engine is to be stopped, the ignition is interrupted, so that the valve member 46 is again pressed against the valve seat 47 by the closing spring, thereby blocking the suction channel 17.

The pump piston 14 will not suck in fuel during the next suction stroke, and the internal combustion engine will stop.

If a failure occurs in the fuel injection pump, suction slit 1
When opening the pump working chamber 15 via one of the
A pressure shock from this pump working chamber 15, which is under high pressure, reaches the magnet valve and loads it with an impact. This type of failure can occur, for example, if the control sleeve 37 occupies an extreme position, for example when the control sleeve 37 sticks to the pump piston 14 and the control lever 3
8 dissociate, so that the transverse hole 3 is opened before the suction slit 16 communicates with the opening of the suction passage into the cylinder bore 13.
9 tends to occur because it cannot be pulled out from the control sleeve even when a predetermined discharge is completed. This pressure impulse lifts the valve member 46 from the valve seat 47 and causes a brief refilling of the pump working chamber 15 via the suction channel. This amount of fuel flowing into the pump working chamber 15 is injected during the next discharge stroke of the pump piston 14, and no stopping of the internal combustion engine by means of the magnetic valve is realized.

In order to avoid this inconvenience and to reliably cause a stoppage of the internal combustion engine when the ignition is stopped and therefore when the magnet valve is stopped energized, two radial holes 4 are provided in the pump piston 14.
8 are provided in the same transverse plane, the radial bores 48 extending into the longitudinal bores 40 of the pump piston 14 and forming in each case a load relief opening with their openings 49 into the outer circumferential surface of the pump piston 14. are doing. At an axial distance from this inner radial bore 48, an annular groove 50 is provided in the pump cylinder I2 starting from the cylinder bore 13, and this annular groove 50 is connected to the pump suction chamber 18 via a connecting bore 51. It is connected to the. When the two load relief openings 49 communicate with the annular groove 50 during the stroke movement of the pump piston 14, a load relief channel is formed between the pump working chamber 15 and the pump suction chamber 18. The high pressure inside the pump working chamber 15 disappears through this load reduction passage, and the pump working chamber 15
A portion of the amount of fuel present within is discharged. The load-reducing openings 49 and the annular groove 50 are arranged in an axial direction such that the pump piston 14 advances a predetermined distance from the bottom dead center, thereby causing the load-reducing openings 49 and the annular groove 50 to overlap. are placed at intervals. This stroke measurement is the maximum allowable piston stroke h until the end of discharge.
rl'l a Larger than H, piston stroke,
small compared to Here, the piston stroke h6 is a stroke performed by the pump piston 14 at a delayed position of the stroke curve with respect to its rotational position until the suction slit 16 connects the pump working chamber 15 and the suction passage 17 before reaching the top dead center OT. means. As can be seen from FIG. 3, the predetermined piston stroke is the maximum piston stroke h-18 that is maintained each time until the end of discharge during the entire operation of the fuel injection pump, and the opening of the suction passage 17 by the suction slit I6. The piston stroke that the pump piston 14 has advanced until it coincides with , exists in the range between . If a problem occurs in the fuel injection control that may cause the internal combustion engine to run out of control, the magnetic valve is killed by cutting off the ignition, thereby blocking the suction passage 17. When the predetermined piston stroke h8 is reached, the load reduction opening 49 and the annular groove 50 overlap and the pump working chamber 15
The load on the pump suction chamber 18 is reduced. This results in
During the piston stroke, the pump working chamber 16 and the suction passage 1
7 is connected via the suction slit 16, the pressure in the pump working chamber 15 disappears, so that there is no longer a pressure in the pump working chamber 15 high enough to bring about a pressure impulse that opens the magnetic valve. Does not occur.

The invention is not limited to the illustrated embodiment. Load reduction above the maximum permissible piston stroke and below the required piston stroke to reach the opening of the pump working chamber before top dead center of the pump piston at the lag position of the stroke curve with respect to the rotational position of the pump piston. The inventive load reduction of the pump work chamber by controlling the opening of the passages is applicable to any fuel injection pump with a pump piston that reciprocates simultaneously with rotation.

[Brief explanation of drawings]

FIG. 1 is a longitudinal sectional view of one embodiment of the present invention, FIG. 2 is a sectional view taken along the line II-II in FIG. 1, and FIG. 3 shows the stroke depending on the rotation angle of the pump piston of the present invention. FIG. DESCRIPTION OF SYMBOLS 11... Pump casing, 12... Pump cylinder, 13... Cylinder hole, 14... Pump piston, 15... Pump working chamber, 16... Suction slit, 17... Suction passage, 18...Pump suction chamber 1
9... Fuel discharge pump, 20... Fuel tank 21
...Pressure control valve, 23...Cam transmission device, 24...
- Drive shaft, 25... Roller, 26... Roller ring, 27... End cam disc, 28... End cam, 29
... Pawl clutch, 30.31 ... Pawl, 32 ... Adjustment bottle, 33 ... Injection adjustment piston, 34 ... Injection adjustment device, 35 ... Return spring, 36 ... Control room ,3
7...Control sleeve, 38...Control lever 39...Horizontal hole, 40...Vertical hole, 41...
- Radial hole, 42... Distribution groove, 43... Pressure conduit, 44... Injection valve, 45... Magnet valve, 46...
... Member, 47... Valve seat, 48... Radial hole, 49
... Load reduction opening, 50 ... Annular groove

Claims (1)

[Claims] 1. A fuel injection pump for an internal combustion engine, comprising a pump cylinder and a pump piston that limits a pump working chamber within the pump cylinder and performs a reciprocating motion at the same time as a rotational motion, the pump cylinder comprising: Opening therein are a suction passage leading to a fuel chamber filled with fuel and a plurality of pressure conduits arranged offset from each other by the same angle of rotation and each connected to an injector valve. For each step,
A number of suction slits corresponding to the number of conduits are provided in the pump piston at intervals of the same rotational angle. Fuel is sucked into the pump working chamber from the suction chamber through the suction passage through one suction slit, and is discharged. During the stroke, fuel is delivered under injection pressure into each one of the pressure conduits via a distribution groove connected to the pump working chamber, the start of delivery being defined by the closure of the suction channel by the pump piston,
The end of the discharge is defined by the control of the opening of the pump working chamber to the suction chamber, in addition an injection regulating device for changing the position of the stroke curve carried out by the pump piston and a suction channel for the end of fuel injection. In the case where the pump piston (14) is provided with a shutoff valve for shutting off the pump working chamber (1
Load reduction passages (40, 48, 49) branching from 5)
, 50, 51), and this process (h_x) is
The suction slit (16) of the pump piston (14) is larger than the maximum permissible pump piston stroke until the end of discharge, and before the pump piston reaches the top dead center (OT), the suction slit (16) of the pump piston (14) connects to the pump working chamber (15) and the suction passage. (17) A fuel injection pump for an internal combustion engine, characterized in that the rotational position of the pump piston 14 is smaller than the pump piston stroke executed at a delayed position of the stroke curve until the pump piston 14 is connected to the pump piston 14. 2. Pump piston (14) and pump cylinder (12)
and two cooperating load relief openings (49, 50).
are provided, one of which has a load reduction opening connected to the pump work chamber (15) and the other load reduction opening connected to a load reduction chamber,
2. The fuel according to claim 1, which is advantageously connected to the suction chamber and is arranged in such a way that the two load relief openings (49, 50) are connected to each other during a given stroke of the pump piston (14). injection pump. 3. One load reduction opening (49) is connected to the pump work chamber (1
5) is formed by the opening of one of the load relief holes (48, 40) connected to the suction chamber, which after a predetermined stroke of the pump piston (14) forms the other load relief opening. 3. The fuel injection pump according to claim 2, wherein the fuel injection pump communicates with a load relief groove (50). 4. The load relief groove is an annular groove (50) inside the pump cylinder (12), and the load relief hole is located inside the pump piston (
The pump piston (14) is formed as at least one radial hole (48) open on the outer circumferential surface of the pump piston (14), and is open on the end face of the pump piston (14) that communicates with this radial hole and limits the pump working chamber of the pump piston (14). 4. The pump piston according to claim 3, wherein the longitudinal bore (40) is formed in the pump piston (14) and the annular groove (50) is connected to a connecting hole (51) leading into the suction chamber (18). fuel injection pump.