EP1297253B1 - Fuel injection device for internal combustion engines - Google Patents

Abstract

The invention relates to a fuel injection device (1) for internal combustion engines, comprising an electrically-activated control valve (9) having an axial through hole (10) which is sub-divided into three ring chambers (11, 12, 13) by means of two valve seats (19, 20). A supply line (7) for fuel under high pressure, a high pressure fuel line (15) leading to an injection valve (8), and a discharge line (17) are respectively connected to said ring chambers. A control piston (14) leads into the through hole (10), comprising two valve sealing surfaces (24, 27) which co-operate respectively with both valve seats (19, 20). According to the invention, the control piston (14) also comprises a further valve sealing surface (25) which co-operates with the first valve seat (19), the distance (h1) thereof from the first valve sealing surface (24) being at least the same as the distance (h2) between the second valve sealing surface (27) and the second valve seat (20) when the first seal seat is closed. A connection between the supply line (7) and the discharge line (17) is thereby definitely avoided.

Description

State of the art

The invention is based on a fuel injection device according to the preamble of claim 1. Such DE 197 01 879 A1 known fuel injection device used to control the injection times and injection quantities of an electrically controlled 3/2-way control valve with one in an axial through hole guided control piston, the one to an injection valve outgoing high-pressure line alternating with a fuel from a high-pressure accumulator (common rail) supplying supply line or connects to a relief line. For this purpose, the through hole through two valve seats in divided into three annular spaces into which the supply line, the Open high-pressure line and the discharge line respectively. The control piston closes during a stroke movement each one valve seat when he the other valve seat releases. For this purpose, the control piston two with the Valve seats cooperating valve sealing surfaces whose Distance is greater than the distance between the two valve seats. Therefore, the supply line, i. the high pressure side, during a stroke of the control piston briefly also with the discharge line, i. with leak oil, directly connected so that a portion of the fuel through the discharge line is diverted. The discarded amount is dependent on the pressure prevailing in the high pressure accumulator and is sometimes considerably higher than the injection quantity.

Advantages of the invention

The fuel injection device according to the invention Internal combustion engines with the characterizing features of Patent claim 1 has the advantage that by the first valve control edge a direct connection between High pressure side and leak oil is reliably prevented. This leads to significantly reduced Absteuermengen and increased the hydraulic efficiency.

In a pressure-controlled injection valve, the control valve be inserted to one of a valve needle the injection valve aufsteuerbaren injection cross section of the injector either with the supply line or to connect with the relief line. The required Delivery rate of the high pressure side, e.g. a high-pressure accumulator, supplying high-pressure fuel pump is thus lower, and also the temperature load of the Fuel tank system with reduced return quantities with high Absteuertemperatur reduced.

In a pressure and cross-section controlled injection valve the control valve can also control the injection cross section be used. advantageously, can use the same valves to control the injection quantity and the injection cross section are used.

Further advantages and advantageous embodiments of the subject The invention are the description, the drawing and the claims.

drawing

Fig. 1

ein erstes Ausführungsbeispiel in einer schematischen Gesamtdarstellung, wobei ein für die Einspritzung verwendetes Steuerventil in vergrößerter Detailansicht dargestellt ist;

Fig. 2

eine vergrößerte Schnittansicht durch das Steuerventil der Fig. 1;

Fign. 3 und 4

Diagramme, die Öffnungsquerschnitte des Steuerventils der Fig. 2 in Abhängigkeit seiner Hubbewegung zeigen;

Fig. 5

das Blockschaltbild des Steuerventils der Fig. 2; und

Fig. 6

ein zweites Ausführungsbeispiel, bei dem das Steuerventil der Fig. 2 zur Querschnittssteuerung von Einspritzventilen verwendet wird.

Two embodiments of the fuel injection device according to the invention for internal combustion engines are shown in the drawing and are explained in more detail in the following description. Show it:

Fig. 1

a first embodiment in a schematic overall view, wherein a control valve used for the injection is shown in an enlarged detail view;

Fig. 2

an enlarged sectional view through the control valve of Fig. 1;

FIGS. 3 and 4

Diagrams showing opening cross-sections of the control valve of Figure 2 as a function of its stroke;

Fig. 5

the block diagram of the control valve of Fig. 2; and

Fig. 6

A second embodiment, in which the control valve of FIG. 2 is used for the cross-sectional control of injection valves.

Description of the embodiments

The designated in Fig. 1 as a whole with 1 first embodiment of a fuel injection device for internal combustion engines has a high-pressure fuel pump 2 , the suction side via a Kraftstofförderleitung 3 with a fuel-filled low-pressure chamber 4 and the pressure side via the delivery line 5 with a high-pressure accumulator (common rail) 6 is connected. From this high-pressure accumulator 6, the high-pressure fuel is discharged via supply lines 7 to the individual, projecting into the combustion chamber of the engine to be supplied pressure-controlled injection valves 8 . To control the injection process each injector 8 is associated with an electrically actuated control valve 9 in the form of a 3/2-way valve.

The control valve 9 has an axial through-bore 10 with an upper, middle and lower annular space 11, 12, 13 and as a control valve member on a run in the through hole 10 control piston 14 . In the upper annular space 11, the supply line 7 opens, and from the middle annulus 12 is a high pressure line 15 , which opens in a known manner in the injector 8 to a aufsteuerbaren by a valve needle 16 of the injector 8 injection cross section of the injector 8. The control piston 14 connects the middle annular space 12 alternately with the upper annular space 11 or with the lower annular space 13, from which a low pressure chamber 4 leading discharge line 17 goes off. The adjustment movement of the control piston 14 is controlled by a solenoid valve 18 which is controlled by an electrical control unit (not shown), which processes a plurality of operating parameters of the engine to be supplied.

As shown in Fig. 2 is an enlarged sectional view of the control valve 9, the middle annulus 12 is separated from the upper annulus 11 by a conical valve seat 19 and from the lower annulus 13 by an annular shoulder 20 . The cross section of the control piston 14 tapers from its upper end initially via two conically shaped upper annular end faces on a central piston portion 21 , opposite which a slide head 22 is widened at its lower end. The diameter of the middle piston portion 21 is smaller than the opening diameter of the valve seat 19 and the annular shoulder 20. The first upper annular end surface 23 is provided in the region of the upper annular space 11, and the second upper annular end surface forms a conical valve sealing surface 24 which is connected to the valve seat 19th interacts. This sealing seat formed between the valve sealing surface 24 and the valve seat 19 closes the upper annulus 11 with respect to the central annulus 12. Adjacent to its conical valve sealing surface 24, the control piston 14 has a first valve control edge 25 formed by the lower edge of a collar 26 . The annular collar 26 is mating ground with little play in the valve seat 19 out, and its lower edge forms together with the valve seat 19 a slide valve. The distance of the first valve control edge 25 to the valve sealing surface 24, that is, the length of the annular collar is designated h1 . With the annular shoulder 20, a second valve control edge 27 cooperates on the slide head 21, wherein the second sealing cross-section formed therebetween closes the connection between the middle and the lower annular space 12, 13. The closing stroke of the slide valve formed by the annular shoulder 20 and the second valve control edge 27 is denoted by h2 and at most as large as the length h1, ie h1 ≥ h2. The fuel discharge from the lower annular space 13 in the discharge line 17 via an opening open to the lower end face 28 of the control piston 14 blind bore 29 , discharges a trained as a throttle point transverse bore 30 and opens into the lower annular space 13.

For actuating the control piston 14, a hydraulic working chamber 31 is provided, which is delimited in the through-bore 10 by the upper end face 32 of the control piston 14 and to the solenoid valve 18 by an intermediate disk 33 . In this intermediate disk 33, a discharge channel 34 discharging from the working space 31 is provided, which can be connected to the low-pressure space 4 via the magnetic valve 18 (FIG. 1). For filling the working chamber 31 with fuel under high pressure, a filling bore 35 having a transverse opening 36 is provided in the control piston 14, the cross section of which is smaller than the cross section of the relief channel 34 and which therefore forms a throttle point. The transverse opening 36 extends below the first annular end face 23 of the control piston 14, so that the working space 31 is connected to the supply line 7 via the filling bore 35 at all times.

The fuel injection device 1 shown in Figs. 1 and 2 operates in the following manner. When starting the system, a high-pressure fuel in the common high-pressure accumulator 6 is first set up via the high-pressure fuel pump 2, which continues through the various supply lines 7 to the respective control valves 9. The solenoid valve 18 is de-energized prior to the start of the injection phase, so that the discharge channel 34 is closed. In this case, the working space 31 is filled via the filling bore 35 with high fuel pressure and presses the control piston 14 due to the area ratio between the end face 32 and the first annular face 23 with the valve sealing surface 24 against the valve seat 19. Thus, the connection between the supply line 7 and the at Injection cross section at the injection valve 8 opening high pressure line 15 closed. At the same time, the second sealing cross section between the second valve control edge 27 and the annular shoulder 20 is opened, so that the pressure in the high pressure passage 15 can relax to a certain residual pressure in the discharge line 17. If an injection takes place at the injection valve 8, first the solenoid valve 18 is energized and thus the discharge channel 34 is released to the low-pressure chamber 4. Since the cross section of the discharge channel 34 is greater than that of the transverse opening 36 in the filling bore 35, the pressure in the working chamber 31 relaxes very quickly via the discharge channel 34 into the low-pressure space 4. The high-pressure fuel present at the annular end face 23 now suffices for the control piston 14 to move. During this opening stroke movement, the valve sealing surface 24 first lifts off the valve seat 19, the first valve control edge 25 still sealing the connection to the middle annular space 12 despite this opened sealing seat. After a stroke h 2, the slide valve is closed by abutment of the second valve control edge 27 on the annular shoulder 20. Either simultaneously when h1 is h2 or after an additional stroke when h1 is greater than h2, the first valve control edge 25 releases the sealing seat and the high pressure fuel in the supply line 7 flows at the central piston portion 21 along in the high pressure passage 15 to the injection valve 8 and lifts there in a known manner, the valve needle 16 against the restoring force of a valve spring 37 of the needle seat, so that the fuel is injected at the injection valve 8 via injection ports 38 into the combustion chamber of the engine to be supplied.

The high-pressure injection at the injection valve 8 is through again Stromlosschalten the solenoid valve 18 is completed. Due to the now closed discharge channel 34 can over the filling hole 35 again a closing pressure in Build working space 31, so that the first valve control edge 25 again closes the valve seat 19 and thus the Connection of the supply line 7 to the high pressure passage 15 again is closed. Either at the same time, if h1 is equal to h2, or only after an additional stroke, though h1 is greater than h2, the gate valve is between the second valve control edge 27 and the annular shoulder 20 again controlled, so that in the high-pressure channel 15th high pressure fuel very quickly in the discharge line 17 relaxed, which is a quick needle closure has the fuel injection valve 8 result.

In the diagram of FIG. 3 , the geometric opening cross-sections A1, A2 are plotted on the first and second valve seats 19, 20 as a function of the stroke movement of the control piston 14, h1 being equal to h2. Only when at a stroke h1 = h2 of the control piston 14 closes the connection between the high pressure line 15 and the discharge line 17, the control piston 14 opens the connection between the supply line 7 and the high pressure line 15th

The course of the geometric opening cross-sections A1, A2, when h1 is greater than h2, is plotted in the diagram of FIG . In a Zwischenhubphase between h2 and h1 both opening cross sections A1, A2 are closed until at a stroke h1 then the control piston 14, the connection between the supply line 7 and the high pressure line 15 opens.

5 shows the block diagram of the control valve 9 acting as a 3/2-way valve, in which the second annular space 12 is connected to the third annular space 13 either in the currentless state or to the first annular space 11 in the energized state.

In Fig. 6 , 40 denotes a second embodiment of a fuel injection device for internal combustion engines with pressure and cross-section controlled injection valves 41 . From the high pressure accumulator 6 goes to each injection valve 41 from an injection line 42 , which opens in a known manner in the injection valve 41 to a aufsteuerbaren from a valve needle 43 of the injection valve 41 injection cross section of the injection valve 41. The injection is controlled by the control valve 9 in the injection pipe 42. The injection openings 44 of the injection valve 41 facing away from the end face 45 of the nozzle needle 43 defines a chamber 46 which is connectable via a discharge line 47 with the low-pressure chamber 4. This connection is hydraulically controlled by a 2/2-way control valve 48 whose high pressure line 49 designed control line via the control valve 9 'with a supply line 50 of the high-pressure accumulator 6 or with the discharge line 17 is connectable. When acted upon by high pressure control line, ie at no-current control valve 9 ', the 2/2-way control valve 48 is closed.

By energizing the control valve 9, the valve needle 43 is raised counter to the restoring force of a valve spring 51 from its needle seat so that the fuel is injected at the injection valve 8 via the injection ports 44 into the combustion chamber of the engine to be supplied via an increase in pressure. Due to the de-energized control valve 9 ', the 2/2-way control valve 48 is closed, and it therefore comes with the trapped in the chamber 46 fuel to a pressure increase, which serves to control the injection cross-section. Is reduced by energizing the control valve 9 ', the pressure in the high-pressure line 49 via the discharge line 17, opens the 2/2-way control valve 48, so that degrades the pressure prevailing in the chamber 46 via the discharge line 47. This causes a further stroke of the valve needle 43, whereby a larger injection cross-section 52 is released to the valve needle 43.

By de-energizing the 3/2-way valve 9, the injection finished, and the valve needle 43 closes under the action of the valve spring 51 the injection openings 44, wherein the chamber 46 again with fuel from the low-pressure chamber 4 is refilled. Then also the control valve 9 'de-energized.

When the all injectors 41 controlling common Control valve 9 'and the control valves 9 on the high-pressure accumulator (Common Rail) 6 are arranged integrated, are small injector dimensions possible. The high pressure line 49 can either at least partially also on the high-pressure accumulator 6 to be integrated, which reduces the construction costs reduced, or a separately arranged Be control line.

Claims (7)

1. Fuel injection device (1; 40) for internal combustion engines, comprising an electrically actuated control valve (9; 9') with an axial through-bore (10) which is divided by a valve seat (19) and an annular shoulder (20) into three annular spaces (11, 12, 13) to each of which a supply line (7 ; 50) for fuel which is under high pressure, a high pressure line (15; 49) which leads away to an injection valve (8; 41) and a relief line (17) are connected, and having a control piston (14) which extends in the through-bore (10) and has a valve sealing face (24) which interacts with the valve seat (19), and an annular collar (26) with a first valve control edge (25) which interacts with the bore wall, defining the seat opening of the valve seat (19), of the through-bore (10), and a second valve control edge (27) which, together with the annular shoulder (20), forms a slider valve, wherein the distance (h1) between the first valve control edge (25) and the valve sealing face (24) is at least equal to the distance (h2) between the second valve control edge (27) and the annular shoulder (20) when the sealing seat is closed.
2. Fuel injection device according to Claim 1,
   characterized in that the distance (h1) between the first valve control edge (25) and the valve sealing face (24) when the sealing seat is closed is greater than the distance (h2) between the second valve control edge (27) and the annular shoulder (20).
3. Fuel injection device according to Claim 1 or 2, characterized in that the annular collar (26) adjoins the valve sealing face (24).
4. Fuel injection device according to one of the preceding claims, characterized in that the valve sealing face (24) and/or the valve seat (19) taper conically in the closing direction of the control piston (14).
5. Fuel injection device according to one of the preceding claims, characterized in that the supply line (7; 50) is connected to a high pressure accumulator (6).
6. Fuel injection device according to one of the preceding claims, characterized in that an injection cross section of the injection valve (8; 41) which can be opened by a valve needle (16; 43) of the injection valve (8; 41) can be connected via the control valve (9) either to the supply line (7) or to the relief line (17).
7. Fuel injection device according to one of the preceding claims, characterized in that the control valve (9') is provided for controlling the cross section of the injection valve (41).

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