JPS6215739B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention is a fuel injection device for an internal combustion engine, comprising:
A fuel pump supplies fuel at a constant pressure to a storage tank, a fuel supply conduit leading from the storage tank to a fuel storage chamber at the valve needle of the fuel injection valve, and a pulse generator driven synchronously with the engine. a control device including a hydraulic fuel circuit, which is actuated to actuate a valve needle loaded in the opening direction with the fuel pressure created in the fuel reservoir; the control piston of each fuel injection valve can be moved periodically, the control device having a solenoid valve controlled by an electrical pulse generator;
By means of this solenoid valve, the working chamber of the control piston can be connected alternately to a pressure line containing a hydraulic medium at a constant pressure and a pressure relief line.

Such an arrangement advantageously ensures that the fuel injection takes place at a constant pressure. In this case, relatively short injection times are obtained compared to known devices with mechanically actuated control circuits. In the fuel injection system of the type mentioned at the outset, the lower limit of the injection time is predetermined by the switching control time of the solenoid valve. This limit lies in the range of about 5 ms for solenoid valves which are common today. However, in practice, even shorter injection times are often desired.

The object of the invention is to provide a fuel injection system which guarantees a high level of functionality at low outlays and which significantly shortens the switching times.

This task is surprisingly solved by the fact that two solenoid valves are provided which can be controlled with a phase shift by an electrical pulse generator, and these solenoid valves are arranged one after the other in the flow direction. Solved in a simple format. This procedure makes it possible to obtain any value in practice by varying the phase shift. In this case, a commercially available solenoid valve that does not change the individual switching control times can be used. Nevertheless, according to the invention, a switching time for all units is obtained which can be significantly reduced compared to the single switching control time.

Moreover, the availability of commercially available bulk products has the advantage of ease of acquisition and stocking and replacement. Furthermore, a unit consisting of two phase-shifted controlled solenoid valves arranged one after the other in the flow direction can be installed anywhere. This is because the two valves arranged one after the other can be easily connected by a conduit.

Furthermore, according to a preferred embodiment of the invention, the solenoid valves arranged one after the other in the flow direction are controlled by a square wave voltage. This square wave voltage is easy to generate and can be derived from any commercially available square wave generator. In this case a defined switching point is obtained by the vertical leg of the square wave.

In yet another embodiment of the invention, the solenoid valve is
It has a control slide that can be actuated by travel magnets located on both legs. Such an arrangement simplifies manufacturing and reduces failures. Furthermore, since the control slide can be constructed with a relatively small mass, a relatively short reaction time is ensured, even though the stroke magnet can be designed relatively compactly.

Furthermore, it is advantageous if at least one of the two solenoid valves is designed as a two-way valve, the two working outlet connections being selectively connectable to a pressure line or a return line of the hydraulic control circuit. . An arrangement in which the hydraulic control circuit is connected directly to the cylinder of the control piston, i.e. with only one supply point.
If there is only one, it is sufficient for the valve at the front in the direction of flow to have one working outlet connection that is connected to the cylinder chamber. This working outlet connection can optionally be connected to the working outlet connection of another valve. In contrast, the hydraulic control circuit has two oppositely movable valves for actuating a high-pressure hydraulic auxiliary circuit, which is connected to the cylinder chamber of the control piston. In the case of the arrangement configuration, both solenoid valves connected one after the other can be
It is advantageous to design it as a directional valve. In this case, the two working outlet connections of the front solenoid valve in the direction of flow are connected to one pressure chamber of the oppositely actuatable valve which acts on the hydraulic auxiliary circuit.

The invention will now be explained with reference to the drawings: In FIG. 1, reference numeral 1 designates a high-pressure tank for fuel. This high-pressure tank 1 is supplied with fuel from a fuel tank 3 via a fuel supply conduit 2 . For this purpose, a high-pressure pump 4, a filter 5 and a feed pump 6 connected to the fuel tank 3 are provided. Advantageously, pumps 4 and 6 operate continuously. For this purpose, a fuel return line 7 leading to the fuel tank 3 is connected to the high-pressure tank 1 . This fuel return conduit 7 is provided with a pressure regulating valve 8 .

A high-pressure line 9 leads from the high-pressure tank 1 to a consumption point, in this case a fuel injection valve 10 of an internal combustion engine. In this exemplary embodiment, the fuel injection valve 10 is connected to the high-pressure line 9 via connecting lines 11, 12. In this case, the connecting line 11 leads to the fuel storage chamber of the fuel injection valve 10, and the connecting line 12 leads to the working chamber of a control piston provided for controlling the valve needle. The injection valve 10 has a pressureless return conduit 13
It is connected to the fuel tank 3 via. All fuel conduits are shown in double lines in FIG.

According to the invention, the device for controlling the opening and closing movements of the valve needle of each fuel injection valve 10 comprises two solenoid valves 14.
a, 14b. These solenoid valves 14a
and 14b are arranged one after the other when viewed in the flow direction. The control unit consisting of the solenoid valves 14a and 14b can actuate a hydraulic control circuit, which cooperates directly or indirectly with the control piston, depending on the respective predetermined injection law. In the illustrated embodiment, the purpose is to periodically conduct the fuel produced at a constant pressure in the connecting line 12 into the working chamber of the control piston. The hydraulic conduits of the hydraulic control circuit are shown in double dashed lines in the drawings. The hydraulic medium to be supplied to the hydraulic pressure control circuit is prepared in a tank 15, and is pumped from the tank 15 to the filter 1 by a pump 16.
7 to a pressure tank 18. The pressure of the hydraulic medium in the pressure tank 18 is kept constant. A pressure regulating valve 19 is provided to monitor the pressure within the pressure tank 18. This pressure regulating valve 19 is connected to the return conduit 2 of the hydraulic medium.
Release 0. From the pressure tank 18 there is a supply conduit 2
1 extends to the individual fuel injection valves 10. From the supply line 21 a pressure line 22 leads to two solenoid valves 14a and 14b arranged one after the other in the flow direction.
It branches off towards a solenoid valve 14a located at the rear in the flow direction of the control unit consisting of. The hydraulic medium escapes to the tank 15 via a common return conduit 23.

A control unit consisting of solenoid valves 14a and 14b is provided with the desired injection type by means of an electronic regulator 24. The electronic regulator 24 is activated by an electrical pulse generator 25, for example a square-wave generator, synchronized with the operation of an internal combustion engine (not shown). For this purpose, the pulse generator 25 receives input pulses, for example from a crankshaft 26 of an internal combustion engine (not shown). The electronic regulator 24 synchronized in this manner with the internal combustion engine is connected to the conduit 27a or 27b.
It is connected to the solenoid valve 14a or 14b via the solenoid valve 14a or 14b. In this case, the line 27a leads to the solenoid valve 14a at the rear in the flow direction, and the line 27b leads to the solenoid valve 14b at the front in the flow direction.
In this case, the electronic regulator 24 has means that enable a predetermined phase shift of the electrical pulses emitted via the tangents 27a and 27b. The magnitude of the phase shift is adjustable by means of an adjustment member designated 28. Electrical conductors are shown in FIG. 1 as solid solid lines.

Solenoid valves 14a or 14b arranged one after the other in the flow direction and controlled with a phase shift
The mode of action of is best shown in the control diagram of FIG. In this case, the control pulses coming from conductors 27a and 27b and the switching positions of the associated solenoid valves 14a and 14b are shown side by side and different switching states successive in time are shown. In this embodiment, both solenoid valves 14a
A two-way valve is used for and 14b. In this case, the adjustable flow channels are shown only by arrows to simplify the drawing. The connections of the solenoid valve 14a are designated by 22a and 23a, corresponding to the pressure line 22 and the return line 23 in FIG. In this case, the connection 22a is connected to the pressure line 22 of the hydraulic control circuit, and the connection 23a is connected to the return line 23. Work outlet connections 220a and 230a face each other to the connections 22a and 23a. The working outlet connections 220a and 230b are connected to a supply point, in this case a pressure chamber of a stroke valve movable in opposite directions. In a preferred embodiment of the invention, the solenoid valves 14a and 14b each have an easily movable control slide for controlling the indicated flow path. This control slide can be actuated by travel magnets arranged on both sides. According to the invention, the travel magnet, which is not shown in the drawings, is excited via a square wave voltage with vertical legs. The voltage curve plotted over time in FIG. 2 is designated with the same reference numeral 27a or 27b as the associated conduit shown in FIG. 1 to simplify the drawing. Code 2 to make the drawing easier to read
The voltage curve marked 7a is shown as a solid line, and the voltage curve marked 27b is shown as a dashed line. In the first switching state shown at the top of FIG. 2, voltage curve 27a has a positive swing and voltage curve 27b has a negative swing. In this case, as can be seen from the circuit diagram shown next to it, the pressure conduit 22 of the hydraulic control circuit is connected to the connection 22a of the solenoid valve 14a, the working outlet connection 230a and the inlet of the solenoid valve 14b connected thereto. Connection part 23b and outlet connection part 230b
connected via. On the other hand, the return conduit 23 of the hydraulic pressure control circuit has connections 23a, 220a, 22
b to the outlet connection 220b of the solenoid valve 14b. As in the switching state shown below the switching state in FIG. 2, the voltage curve 27a
When the deflection becomes negative, the associated solenoid valve 14a is switched over. The flow path passing through the solenoid valves 14a and 14b, which is connected to the pressure line 22 of the hydraulic control circuit, is connected to the working outlet connection 22 via the connection 22a.
0b and from there via the connection 22b to the working outlet connection 220b of the solenoid valve 14b. On the other hand, the return conduit 23 of the hydraulic circuit connected to the connection 23a is connected to the working outlet connection 230 of the solenoid valve 14b.
connected to b. In this state, therefore, the supply point connected to the working outlet connection 220b is loaded with hydraulic medium, and the feeding point connected to the working outlet connection 230b is unloaded. In the next switching state, this relationship is reversed again. For this purpose, according to the invention, it is not necessary to wait until the voltage curve 27a swings positive again. This is because a positive deflection of the previously phase-shifted voltage curve 27b has already taken place. In this case, the pressure conduit 22 of the hydraulic pressure control circuit is connected to the connection 22a and the working outlet connection 220.
a, connected to the working outlet connection part 230b of the solenoid valve 14b via the connection part 22b. On the other hand, solenoid valve 1
The work outlet connection part 220b of 4b is connected to the connection part 23b,
It is connected via 230a and 23a to the return conduit 23 of the hydraulic control circuit. According to the invention, therefore, the switching time of the control unit consisting of the solenoid valves 14a and 14b is independent of the switching time of the individual solenoid valves, and can be set to any desired value by means of the adjusting member 28. It turns out that it only concerns the phase shift, which is also adjustable. If in the next period the deflection of the voltage curve 27a becomes positive again, the connection 22 of the solenoid valve 14a
a is connected to the work outlet connection part 230a, and as a result, the position of the solenoid valve 14b is kept unchanged, so that the work outlet connection part 220 of this solenoid valve 14b is connected to the work outlet connection part 230a.
connected to b. On the other hand, the working outlet connection 230b of this solenoid valve 14b is connected to the connection 2 of the solenoid valve 14a.
3a. If the voltage curve 27b then swings negative, the switching state shown at the top is again obtained.

The cooperation of the unit consisting of the solenoid valves 14a and 14b and the injection valve to achieve short injection times is shown in particular detail in FIG. In this case as well, the basic structure corresponds to the circuit diagram described above. Therefore, the same parts are given the same reference numerals. In the illustrated embodiment, the injection valve 10 is supplied directly via a connecting line 11 with fuel which is present at constant pressure in a high-pressure tank. This fuel is conducted in a known manner through holes 30 into ring passages 31. From here, a number of supply conduits 32 lead to a fuel storage chamber 33. The injection opening 34 of this fuel storage chamber 33 can be closed by the needle valve 35 against a constant fuel pressure in the fuel storage chamber 33 acting in the opening direction on the working surface 36 of the needle valve 35 . A control piston 37 , which is arranged coaxially with the injection valve 10 , acts on the needle valve 35 . This control piston 37 delimits a hydraulic working space with a working surface 38 opposite the needle valve 35 . control piston 3
The working chamber 39 of 7 can be loaded with hydraulic medium via a pressure line 40. In the illustrated embodiment, a constant pressure of fuel in the high-pressure tank 1 is used for this purpose. This fuel is conducted via a connecting conduit 12 opening into a pressure conduit 40. A pressure relief line 41 is connected to the fuel return line 13 in order to unload the hydraulic work chamber. In this case, the pressure line 40 and the pressure relief line 41 form a hydraulic auxiliary circuit which can be controlled by the actual control circuit according to the invention. The communication from connecting line 12 to pressure line 40 can therefore be shut off via valve 42, which in this case is designed as a needle valve. Pressure relief line 41 can likewise be shut off via valve 43. Valves 42 and 43 are movable periodically in opposite directions by means of pressure pistons 44 and 45 assigned to them. A pressure chamber 46 or 47 is assigned to each pressure piston 44 and 45. These pressure chambers 46, 47 are integrated into a hydraulic control circuit and include phase-shifted controllable solenoid valves 14a arranged one behind the other in the flow direction.
Alternatively, it can be connected by 14b to the pressure line 22 or to the return line 23 of the hydraulic control circuit in the manner described in detail in FIG.

According to the invention, the solenoid valves 14a and 14b are constructed as conventional two-way valves. This two-way valve has a control slide 50 supported in a bore in the valve casing with pistons 51 and 52 connected by webs 53.
have. Depending on the pistons 51 and 52,
Pressure conduit 22 or return conduit 2 of the hydraulic control circuit
3 and the connection part 22a of the solenoid valve 14a connected to 2
3a and the connections 22b and 23 of the solenoid valve 14b
b is the associated working outlet connection 2 of the solenoid valve 14a, which is connected to the connections 22b and 23b of the solenoid valve 14a.
20a and 230a or alternatively to the working outlet connections 220b and 230b of the solenoid valve 14b. The connection of the solenoid valve as well as the working outlet connection are advantageously designed as radial housing bores. In the illustrated embodiment, the connecting portion 23a or 23b is branched into two parts, between which the connecting portion 22a or 22b extends. In the illustrated embodiment, a solid plate 54 is arranged between the valves 14a and 14b. This plate 54 has an annular groove 55 into which a working outlet connection 230a of the solenoid valve 14a opens, from which a branched connection 23b of the solenoid valve 14b extends. The working outlet connection 220a of the solenoid valve 14a is connected via a through hole 56 to a connection 22b configured as a radial housing bore of the solenoid valve 14b. Solenoid valve 14b
The working outlet connections 220b and 230b are connected to the connection hole 5.
It is connected to the pressure chamber 46 or 47 via 7 and 58. The control slider 50 is connected to the spring 5 from both sides.
It is supported by 9. For actuating the control slide 50, travel magnets 60 arranged on both sides are provided. The end of the control slide 50 protrudes into the stroke magnet 60 in the form of a mover.

In this case, by cyclic movement of the control slide 50, the pressure chambers 46 and 47 can be selectively loaded or unloaded with hydraulic medium. In the case shown, solenoid valves 14a and 14b
The control slider 50 is connected to the pressure conduit 22 of the control circuit.
is connected to the pressure chamber 47 and the return conduit 23 of the hydraulic control circuit is connected to the pressure chamber 46. The valve body of the valve 42 is therefore lifted under the action of the hydraulic medium under high pressure conveyed through the conduit 12, the cylinder chamber 39 is brought under pressure and the valve needle 35 is thus brought up. It is crimped onto the valve seat. This switching state corresponds to the block diagram shown at the top of FIG. Moving to the next switching phase, pressure chamber 46 is loaded and pressure chamber 47 is depressurized. In this case, the valve 43 is separated from the valve seat, and the pressure chamber 3
9 load is removed and injection is then started.
Phase shift controlled solenoid valves 14a and 14 according to the invention
b achieves the shortest injection time.

In an arrangement in which it is sufficient without a hydraulic auxiliary circuit, i.e. in which the pressure chamber 39 can be loaded directly by the pressure conduit 22 or unloaded by the return conduit 23, in the flow direction. It is sufficient if the front solenoid valve has only one working outlet connection.

[Brief explanation of the drawing]

The drawings show one embodiment of the invention,
Fig. 1 is a schematic diagram showing the structure of the fuel injection device of the present invention, Fig. 2 is a diagram and circuit diagram showing time-related control of the fuel injection device of the present invention, and Fig. 3 is an injection valve and flow direction. FIG. 2 is a sectional view of a control unit consisting of solenoid valves arranged one after the other; 1... High pressure tank, 2... Fuel supply conduit, 3...
... Fuel tank, 4 ... High pressure pump, 5 ... Filter, 6 ... Supply pump, 7 ... Fuel return conduit, 8
...Pressure regulating valve, 9...High pressure conduit, 10...Fuel injection valve, 11, 12...Connecting conduit, 13...Return conduit, 14a, 14b...Solenoid valve, 15...Tank, 16...Pump , 17...filter, 18...
...pressure tank, 19...pressure regulating valve, 20...return conduit, 21...supply conduit, 22...pressure conduit,
23...Return conduit, 24...Electronic regulator, 25...
...Pulse generator, 26...Crankshaft, 27a,
27b...Conducting wire, 28...Adjustment member, 30...
Hole, 31...Ring passage, 32...Supply conduit, 3
3... Fuel storage chamber, 34... Injection port, 35... Needle valve, 36... Working surface, 37... Control piston, 38... Working surface, 39... Working chamber, 40...
Pressure conduit, 41...Pressure relief conduit, 42, 43
... Valve, 44, 45 ... Pressure piston, 46, 4
7...Pressure chamber, 50...Control slider, 51,5
2...Piston, 53...Web, 54...Plate,
55...Ring groove, 56...Through hole, 57, 58
... Connection hole, 59 ... Spring, 60 ... Stroke magnet.

Claims (1)

[Claims] 1. A fuel injection device for an internal combustion engine, comprising a fuel pump that supplies fuel at a constant pressure to a storage tank;
It has a fuel supply conduit leading from the storage tank to the fuel storage chamber at the valve needle of the fuel injection valve, and a control device including a hydraulic control circuit operated by a pulse generator driven synchronously with the engine. The control device allows the control piston of each fuel injection valve to be moved cyclically in order to actuate the valve needle which is loaded in the opening direction with the fuel pressure created in the fuel storage chamber. The control device has a solenoid valve controlled by an electric pulse generator, by means of which the working chamber of the control piston is controlled by a hydraulic medium at a constant pressure. In a type that can be connected alternately to a pressure conduit containing a pressure conduit and a pressure relief conduit,
Fuel for an internal combustion engine, characterized in that two solenoid valves are provided which can be controlled with a phase shift by an electric pulse generator, the solenoid valves being arranged one after the other in the flow direction. Injection device. 2. The fuel injection device for an internal combustion engine according to claim 1, wherein the electromagnetic valves 14a and 14b can be controlled with a square wave voltage. 3 The solenoid valves 14a, 14b each have one control slider 50, which control slider 5
2. A fuel injection device for an internal combustion engine according to claim 1, wherein the fuel injection device is actuatable by stroke magnets 60 arranged on both sides. 4 At least one of both solenoid valves has two working outlet connections 220a, 230a; 220b, 230
220 is configured as a two-way valve with b and two working outlet connections 220a, 230a;
b, 230b are hydraulic pressure control circuits 25, 58, 46,
23. A fuel injection device for an internal combustion engine according to claim 1, which can be selectively connected to the pressure conduit 22 or the return conduit 23 of 23, 57, 47. 5. The hydraulic control circuit is connected directly to the cylinder chamber of the control piston, and the forward solenoid valve 14b, seen in the direction of flow, has only one working outlet connection connected to the cylinder chamber of the control piston. 2. A fuel injection device for an internal combustion engine according to claim 1, wherein the working outlet connection is selectively connectable with a working outlet connection of another valve. 6. the hydraulic control circuit has two oppositely movable valves for actuating a high pressure hydraulic auxiliary control circuit, the hydraulic auxiliary control circuit being connected to the cylinder chamber of the control piston; Both solenoid valves 14
a, 14b are configured as two-way valves, the two working outlet connections 220b, 230b of the front valve 14b being movable in opposite directions in the flow direction;
The fuel injection device for an internal combustion engine according to claim 1, wherein the fuel injection device is connected to the pressure chambers 46 and 47 of 43.