JPH08210223A - Fuel high-pressure pump used for internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To forcibly supply fuel of high pressure so as to forcibly supply only a discharge rate which is necessary for the time being. SOLUTION: An outer peripheral surface of a pump plunger 9 has a control cutout 37 cooperated with a control hole 19, which is connected to a pump actuating chamber 17 at all times, the lower edge part of a side opposite to the pump actuating chamber 17 of the control cutout 37 forms a control edge part 39 for controlling delivery start of high-pressure delivery. The control edge part 39 is arranged aslant in a pump plunger axis, and the pump plunger 9 is rotatably guided for regulating the delivery start of the high-pressure delivery.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fuel high-pressure pump used in an internal combustion engine, which is provided with a pump plunger axially reciprocally driven in a cylinder hole provided in a cylinder bush. One end face partitions the pump working chamber, the pump working chamber is connected to the low pressure chamber filled with fuel through a control hole provided in the cylinder bush, and the discharge pipeline is further connected. The present invention relates to a type in which an injection pipe line is led out from the high pressure collection chamber via the high pressure collection chamber and communicates with each injection valve provided in the internal combustion engine.

[0002]

2. Description of the Prior Art A fuel high-pressure pump of this type is known from EP 0 307 947 A1. This known fuel high pressure pump pumps fuel from a low pressure chamber to a high pressure collection chamber. From this high-pressure collection chamber, a large number of injection pipe lines are led out to communicate with the individual injection valves that have plunged into the combustion chamber of the internal combustion engine to which fuel is to be supplied (Co
mmon Rail). This known fuel high-pressure pump is formed as a plunger pump with a plurality of pump plungers. The pump plunger guided in each one cylinder hole provided in the cylinder bush is axially reciprocally driven by a common cam drive device. The end face of the pump plunger on the side opposite to the cam drive device partitions the pump working chamber. This pump working chamber is filled with fuel from the low pressure chamber via a control hole provided in the wall of the cylinder bush. Furthermore, this pump working chamber is connected to the high-pressure collection chamber via a discharge line. The high-pressure discharge in the pump working chamber is started at the same time when the control hole is completely overcome by the pump plunger during the discharge stroke movement of the pump plunger, so that when the discharge stroke of the pump plunger is continued, the enclosed pump is closed. A high fuel pressure is created in the working chamber. When the specified pressure is exceeded, the high pressure of the fuel controls the opening of the discharge valve provided in the discharge conduit, so that the fuel under high pressure is pumped into the high pressure collection chamber. In the known fuel high pressure pump, the control of the high pressure discharge amount is performed by a pressure control valve inserted in a bypass line between the discharge line and the low pressure chamber. The pressure control valve is in this case formed as a solenoid valve. This solenoid valve closes the pump working chamber relative to the low pressure chamber at a specified time during the discharge stroke movement of the pump plunger in relation to the desired discharge rate, thus initiating high pressure discharge. This high pressure discharge is continued until the top dead center of the pump plunger stroke movement is reached.

However, the following drawbacks are recognized in this known fuel high-pressure pump. That is, controlling the discharge amount using the solenoid valve provided in each pump plunger is relatively time-consuming and expensive. Further, a drawback is recognized in that unnecessary fuel is closed and controlled at the end of high-pressure discharge. That is, fuel under high pressure can flow into the low pressure system, affecting the suction process of the individual pump plungers at this location, and due to the sharp closed control jet, damage the walls of the high pressure pump. is there.

[0004]

SUMMARY OF THE INVENTION The object of the invention is to improve the high-pressure fuel pump of the type mentioned at the outset so that only the required discharge quantity is actually pumped under high pressure. It is an object of the present invention to provide a fuel high-pressure pump capable of discharging fuel.

[0005]

In order to solve this problem, in the structure of the present invention, the outer peripheral surface of the pump plunger has a control notch which is always connected to the pump working chamber and cooperates with the control hole. The lower edge of the control notch on the side opposite to the pump working chamber forms a control edge for controlling the start of high-pressure discharge, and the control edge is the pump plunger axis. And the pump plunger is rotatably guided to adjust the discharge start of the high pressure discharge.

[0006]

The high-pressure fuel pump according to the present invention has the following advantages over the conventional one. That is, it is structurally possible to simply discharge the fuel under high pressure so that only the required discharge amount is actually pumped. The undesired discharge volume is pushed out of the pump working chamber into the low pressure chamber at the pressure of the low pressure chamber before the start of the high pressure discharge during the discharge stroke of the pump plunger, in this case this was provided on the wall of the cylinder bushing. Advantageously, it is not necessary to provide an additional opening or line, since it is carried out via a control hole which allows inflow. This is
The manufacturing effort is reduced compared to known systems.

It is advantageous that the control of the high-pressure discharge amount is performed by the variable start and the constant discharge end of the high-pressure discharge. In this case, the start and end of the high-pressure discharge are controlled by mechanical means. For this purpose, a control notch, which is always connected to the pump working chamber, is formed on the outer peripheral surface of the pump plunger. Of this control notch,
A lower edge portion on the side opposite to the pump working chamber forms a control edge portion that controls the discharge start of the high pressure discharge. The control edge cooperating with the control hole is in this case arranged obliquely with respect to the pump plunger axis, so as to adjust the variable effective stroke for the high-pressure discharge in relation to the rotational position of the pump plunger. be able to.

Further, since a fuel which is only under a low pressure flows out from the pump working chamber, a check valve or a suction throttle is not required in the suction pipe line leading from the reservoir tank to the high pressure pump, so that the check valve or Almost no loss output occurs at the suction throttle. This increases the efficiency of the overall system.

The end of discharge is constant at the top dead center of the pump plunger, in which case an additional second notch connected to the pump working chamber, which in some cases releases the residual pressure in the pump working chamber. Can be provided on the pump plunger. The second notch overlaps the control hole in the range of the top dead center of the pump plunger.

In order to obtain a symmetrical pressure distribution in the pump plunger, it is alternatively possible to provide a plurality of control notches which are evenly distributed over the entire circumference.
Each of these control notches cooperates with a corresponding control hole.

Further, based on the relatively simple adjustment of the rotational position of the pump plunger using the control rod,
Another advantage is obtained. This is particularly advantageous when a plurality of pump plungers (row pump structure) arranged in rows are provided. In this case, these pump plungers can be adjusted by means of only one common control rod, and the use of a control sleeve provided on the pump plungers allows a simple equalization of the individual pump plunger elements.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described in detail below with reference to the drawings.

FIG. 1 shows only the components of the high-pressure fuel pump 1 used in an internal combustion engine which are important for the invention. In this fuel high-pressure pump 1, a cylinder bush 3 is inserted in a pump housing 5. The cylinder bush 3 has a cylinder hole 7, and a pump plunger 9 is guided in the cylinder hole 7. This pump plunger 9 is of a known type and is of the cam drive 1
By means of 1, the shaft is reciprocally driven in the axial direction against the spring force of the return spring 13. An end surface 15 of the pump plunger 9 on the side opposite to the cam drive device 11 partitions a pump working chamber 17 in the cylinder bush 3. This pump work room 1
Reference numeral 7 is connected to the low pressure chamber 21 via a control hole 19 arranged in the wall of the cylinder bush 3 in the radial direction. The low-pressure chamber 21 is filled with fuel from a fuel reservoir tank (also not shown) via a supply line (not shown). Further, from the upper end of the pump working chamber 17 on the side opposite to the pump plunger 9, the discharge pipe line 2 having the discharge valve 23 is formed.
5 has been derived. On the other hand, this discharge line 25 opens into a high-pressure collection chamber 27. This high pressure collection chamber 2
From FIG. 7, a plurality of injection pipe lines 29 corresponding to the number of injection points provided in the internal combustion engine to which fuel is to be supplied are led out and communicate with an injection valve 31 that rushes into the combustion chamber of the internal combustion engine ( Common Rail System).

The pump plunger 9 is rotatable in a known manner via a control rod 33 loaded by an actuating member. For this purpose, the control rod 33 acts on a control sleeve 35 arranged on the pump plunger 9 such that it cannot rotate relative to it.

To control the high-pressure discharge, the end of the pump plunger 9 facing the pump working chamber 17 has a control notch 37 which is always connected to the pump working chamber 17. The lower edge of the control cutout 37 on the side opposite to the pump working chamber 17 forms a control edge 39. The control edge portion 39 cooperates with the control hole 19 to control the start of high-pressure discharge in the pump working chamber 17. The control edge 39 is arranged obliquely to the pump plunger axis, in which case five variants of the control cutout 37 are shown in FIGS.

FIG. 2 shows a first embodiment of the control notch 37 provided in the pump plunger 9. This control notch 37 directly follows the end face 15 of the pump plunger 9 and thus allows a smooth fuel flow from the pump working chamber 17 to the control notch 37. The control edge 39 extends at an angle to the pump plunger axis. The magnitude of this angle is related to the magnitude of the maximum amount of fuel desired to be pumped.

In the second embodiment shown in FIG. 3, a web 43 forming a head collar is formed between the upper edge 41 of the control notch 37 near the pump working chamber 17 and the end face 15 of the pump plunger 9. Is provided. This web 43 improves the guide of the pump plunger 9 in the cylinder bore 7,
As a result, the pump plunger 9 is prevented from being caught. In the second embodiment shown in FIG. 3, the hydraulic connection between the control cutout 37 and the pump working chamber 17 is made via the axial groove 45. The axial groove 45 extends from the end face 15 as a starting point and communicates with the control notch 37.

The third embodiment shown in FIG. 4 differs from the second embodiment in the construction of the hydraulic connection between the pump working chamber 17 and the control cutout 37. In the third embodiment, the hydraulic connection between the pump working chamber 17 and the control cutout 37 is the end face 15 of the pump plunger 9.
Is formed by an axial blind hole 47 extending from the starting point. This blind hole 47 is intersected by a lateral hole 49 in the pump plunger 9 which opens into the control cutout 37.

The fourth embodiment shown in FIG. 5 of the control notch 37 provided in the pump plunger 9 is the second embodiment shown in FIG.
It is almost equivalent to the embodiment. In the fourth embodiment, the second
In addition to the configuration of the exemplary embodiment, a second cutout 51 is provided below the control cutout 37 on the side facing away from the pump working chamber 17. This second notch 51 is formed as a rectangular pocket, in which case lateral grooves are also possible. The second notch 51 is provided with the control hole 1 at the top dead center position of the pump plunger 9, that is, at the end of the discharge stroke movement.
It is arranged on the pump plunger 9 so as to overlap with 9. In this case, the second cutout 51 shown in FIG. 5 is hydraulically connected via the extension of the axial groove 45 to the control cutout 37 and thus to the pump working chamber 17.

The fifth embodiment shown in FIG. 6 is similar to the fourth embodiment shown in FIG. 5 in that the structure of the third embodiment shown in FIG. 4 is the same as that of the second notch 51. It is an extension.
The second notch 51 is also formed on the outer peripheral surface of the pump plunger 9 at a height overlapping the control hole 19 at the top dead center position of the pump plunger 9. Second
The second lateral hole 53 opening in the notch 51 is connected to the pump working chamber 17 following the end face 15 of the pump plunger 9.

The notches 37 and 51 shown in FIGS. 2 to 6 can be provided in pairs. In this case, the recesses 37, 51 are located diametrically opposite one another and cooperate with each one corresponding control hole 19.

The working mode of the fuel high-pressure pump 1 according to the present invention will be described below with reference to FIGS. 7 to 1
0 shows the pump plunger 9 with the control cutout 37 shown in FIG. 2 in various positions with respect to the control hole 19 provided in the wall of the cylinder bushing 3. At the position shown in FIG. 7, the pump plunger 9 is located at the bottom dead center position. At this bottom dead center position, the flow cross section along the control notch 37 between the control hole 19 and the pump working chamber 17 is open. In this case, it is also possible to arrange the control hole 19 in this stroke position of the pump plunger 9 so that the control hole 19 opens directly into the pump working chamber 17 just above the end face 15 of the pump plunger 9. In this plunger position at the end of the downwardly directed suction stroke movement, the pump working chamber 17 is filled with fuel under low pressure from the low pressure chamber 21.

After passing through the bottom dead center position, the pump plunger 9 is moved by the cam drive device 11 in the direction of top dead center against the spring force of the return spring 13, in which case this discharge stroke of the pump plunger 9 is carried out. During exercise, the volume in the pump working chamber 17 is gradually reduced. At this time, an amount of fuel not required for high-pressure discharge is first pushed out from the pump working chamber 17 to the low-pressure chamber 21 via the control hole 19 at a low pressure. This idle stroke movement is carried out until the control edge 39 completely rides over the control hole 19, as shown in FIG. The timing is adjustable via the rotational position of the pump plunger 9. After the time has passed, high-pressure discharge in the enclosed pump work chamber is started.
The volume of the pump working chamber is further reduced during the discharge stroke movement of the pump plunger 9 (FIG. 9), which, as is known, results in an increase in the pressure of the fuel in the pump working chamber 17. When the specified limit pressure is reached, the discharge valve 23 is opened, the fuel under high pressure flows into the high pressure collection chamber 27 via the discharge pipe line 25, and the fuel is further discharged from this high pressure collection chamber 27. It is supplied to the injection valve 31 via the injection pipe 29. The opening timing of the injection valve 31 can be controlled via an electromagnetic valve provided in the injection valve 31.

The effective stroke of the pump plunger 9 for high-pressure discharge continues to the top dead center shown in FIG. 10, in which case the high pressure of fuel has completely flown into the high-pressure collection chamber 27.
Since the discharge valve 23 is closed when the specified pressure drop in the pump working chamber 17 is achieved, the discharge end of the high pressure discharge is constant at any rotational position of the pump plunger. At the top dead center, it is possible to control the opening of the second notch 51 for the purpose of reducing the residual pressure that may occur in the pump working chamber 17. This results in a pressure relief of the pump working chamber 17, which also has a positive effect on the refilling of the pump working chamber 17. As is well known, a suction stroke follows the top dead center of the stroke movement of the pump plunger 9. In the course of this suction stroke, the control cutout 37 controls the opening of the control hole 19 again, and the fuel can flow from the low pressure chamber 21 into the pump working chamber 17 again.

Advantageously, a plurality of pump plungers 9 are provided. These pump plungers 9 are arranged in rows with respect to one another, as is the case with fuel injection pumps of the row pump type. Therefore, by using the fuel high-pressure pump according to the present invention, it is structurally possible to set a variable discharge start timing and a constant discharge end timing, and thus limit the high-pressure discharge to a required fuel amount. .

[Brief description of drawings]

FIG. 1 is a vertical sectional view of a fuel high-pressure pump according to the present invention.

FIG. 2 is a schematic view showing a first embodiment of a control notch provided in a pump plunger.

FIG. 3 is a schematic view showing a second embodiment of the control notch provided in the pump plunger.

FIG. 4 is a schematic view showing a third embodiment of the control notch provided in the pump plunger.

FIG. 5 is a schematic view showing a fourth embodiment of the control notch provided in the pump plunger.

FIG. 6 is a schematic view showing a fifth embodiment of the control notch provided in the pump plunger.

FIG. 7 is a schematic view showing one discharge stroke position of the pump plunger with respect to the control hole.

FIG. 8 is a schematic view showing another discharge stroke position of the pump plunger with respect to the control hole.

FIG. 9 is a schematic view showing still another discharge stroke position of the pump plunger with respect to the control hole.

FIG. 10 is a schematic view showing still another discharge stroke position of the pump plunger with respect to the control hole.

[Explanation of symbols]

1 Fuel High Pressure Pump, 3 Cylinder Bush, 5 Pump Housing, 7 Cylinder Hole, 9 Pump Plunger, 11 Cam Drive Device, 13 Return Spring, 1
5 end faces, 17 pump working chambers, 19 control holes,
21 low pressure chamber, 23 discharge valve, 25 discharge line,
27 high pressure collection chamber, 29 injection line, 31 injection valve, 33 control rod, 35 control sleeve, 37 control notch, 39 control edge,
41 upper edge, 43 web, 45 axial groove,
47 blind hole, 49 lateral hole, 51 second notch, 53 second lateral hole

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Gottfried Kuhne E.t. Bachstrasse 8

Claims (7)

[Claims] 1. A fuel high-pressure pump used in an internal combustion engine, comprising a pump plunger (9) axially reciprocally driven in a cylinder hole (7) provided in a cylinder bush (3), One end surface (15) of the pump plunger (9) partitions the pump working chamber (17), and the pump working chamber (17) has a control hole (19) provided in the cylinder bush (3). Is connected to the low pressure chamber (21) filled with fuel via the discharge line (25) and to the high pressure collection chamber (27) via the discharge line (25). An injection pipe (29) is derived from the injection pipe (29) and is provided in the internal combustion engine.
Of the type communicating with the control hole (19), the outer peripheral surface of the pump plunger (9) is always connected to the pump working chamber (17) and cooperates with the control hole (19).
7), the lower edge of the control notch (37) on the side opposite to the pump working chamber (17) forms a control edge (39) for controlling the discharge start of the high-pressure discharge. The control edge (39) is arranged obliquely with respect to the pump plunger axis, and the pump plunger (9) is rotatably guided for adjusting the discharge start of the high-pressure discharge. A high-pressure fuel pump used in an internal combustion engine, characterized in that 2. The upper end of the control notch (37) near the pump working chamber (17) and the pump plunger (9).
2. The high-pressure fuel pump according to claim 1, wherein an annular web (43) is provided on the outer peripheral surface of the pump plunger (9) between the end surface (15) partitioning the pump working chamber (17). 3. The outer peripheral surface of the pump plunger (9) and the pump working chamber (17) at all times below the end of the control notch (37) on the side opposite to the pump working chamber (17). Another connected cutout (51) is provided, which cutout (51) is in the range of the top dead center of the pump plunger (9) during the discharge stroke movement of the pump plunger (9). Fuel high pressure pump according to claim 1 or 2, which overlaps with the control hole (19) provided in 3). 4. The notches (37, 51) provided in the pump plunger (9) are the pump plunger (9).
4. The high-pressure fuel pump according to claim 1, which is connected to the pump working chamber (17) through an axial groove (45) provided in the pump. 5. The two notches (37, 51) provided in the pump plunger (9) are the pump plunger (9).
A blind hole (47) extending in the axial direction starting from the end surface (15) of the same, and the notches (37, 5) formed in the pump plunger (9) and intersecting the blind hole (47).
4. The pump working chamber (17) is connected via a lateral hole (49, 53) opening in 1).
The fuel high-pressure pump according to any one of items 1 to 7. 6. The pump plunger (9) is provided with two control notches (37) located diametrically opposite one another, both control notches (37) being provided on the cylinder bush (3). 5. The high-pressure fuel pump according to claim 1, which cooperates with two control holes (19) provided facing each other. 7. A control rod (3) for adjusting the rotational position of the pump plunger (9) acting on a control sleeve (35) fixed to the pump plunger (9).
The high-pressure fuel pump according to claim 1, which is carried out via 3).