EP0451227A1

EP0451227A1 - Fuel injection pump.

Info

Publication number: EP0451227A1
Application number: EP19900914055
Authority: EP
Inventors: Heinz Nothdurft; Reinhard Trunk; Kurt Sprenger; Carlos Alvarez-Avila
Original assignee: Robert Bosch GmbH
Current assignee: Robert Bosch GmbH
Priority date: 1989-10-20
Filing date: 1990-09-28
Publication date: 1991-10-16
Anticipated expiration: 2010-09-28
Also published as: EP0451227B1; JP3145108B2; DE3934953A1; RU2018758C1; ES2066225T3; DE59008029D1; JPH04502502A; WO1991005950A1; US5150688A

Abstract

Une électrovanne servant à la coupure d'une conduite d'aspiration de carburant (10) pour l'alimentation en carburant d'un espace de travail d'une pompe d'injection de carburant, présente sur la partie de fermeture (28) un trou (50) entrant par le devant et pouvant être obturé au moyen d'un élément de soupape (61) sous l'effet d'un ressort de fermeture (57). En présence d'à-coups de pression dans le tronçon de la conduite d'aspiration (31) obturée par la partie de fermeture (28) et menant vers l'espace de travail de la pompe, la partie de fermeture (28) et toute la section de la partie de la conduite d'aspiration (31) ne s'ouvrent pas, mais uniquement la section du trou (50). Ce trou, après avoir été ouvert, est rapidement refermé par l'élément de soupape (61) à faible masse, de façon que seulement de faibles quantités de carburant puissent passer à travers le trou (50) en vue de l'égalisation de pression.A solenoid valve for shutting off a fuel suction line (10) for supplying fuel to a working space of a fuel injection pump, provided on the closing part (28) a hole (50) entering from the front and being able to be closed by means of a valve element (61) under the effect of a closing spring (57). In the presence of pressure surges in the section of the suction line (31) closed by the closing part (28) and leading to the working space of the pump, the closing part (28) and the entire section of the part of the suction line (31) does not open, but only the section of the hole (50). This hole, after being opened, is quickly closed by the low mass valve member (61) so that only small amounts of fuel can pass through the hole (50) for pressure equalization. .

Description

Solenoid valve, in particular for fuel injection pumps

State of the art

The invention is based on a solenoid valve according to the preamble of the main claim. In such a solenoid valve known from DE-PS 25 03 345, the closing part is coupled to the armature of the solenoid valve via a towing coupling and the armature is designed as a valve member with its end face immersed in the closing part, so that it shares the connection between the suction lines locks over the hole when the armature brings the closing part into the closed position or has brought it under the action of the return spring. When the solenoid valve is opened ^* under the influence of the magnetic force of the electromagnet, the armature is lifted from its seat on the closing part, opens the hole and only lifts the closing part from its seat via the drag clutch during a further stroke, so that the force required for Opening of the closing part, which is acted upon both by the return spring and by the pressure prevailing upstream of the seat in the suction line, can be kept small, since pressure compensation takes place beforehand via the bore. Under certain conditions, however, it can happen with a solenoid valve of the generic type that the closing part, when it is brought into the closed position, is acted upon by a pressure surge from the pump work space in the course of the remaining delivery stroke of the fuel injection pump and after opening the connection between the suction line and the pump work space. This pressure surge can lead to the closing part being lifted from its seat and that a refilling process of the pump work space can now take place briefly via the suction line. This quantity flowing into the pump work space can continue to be injected during the next delivery stroke of the pump piston and the purpose of the solenoid valve serving to shut off is therefore not achieved. In particular, if there is another fault in the control of the fuel injection pump, the internal combustion engine can fail.

Advantages of the invention

The solenoid valve according to the invention with the characterizing features of the main claim has the advantage that an opening of the closing part and thus a correspondingly large fuel flow to the pump work space is prevented, since the pressure surge via the opening valve member, which releases only a small overflow cross section, is reduced.

Advantageous further developments and improvements of the solution specified in the main claim are possible through the measures listed in the subclaims. In particular, according to the embodiments according to claims 4 and 5, there is a small, low-mass valve member which can return to the closed position with low inertia, so that only a minimal backflow effect takes place after the valve member is pushed open. This largely avoids the disadvantages mentioned at the outset. drawing

An embodiment of the invention is shown in the drawing and is explained in more detail in the following description. FIG. 1 shows a partial longitudinal section through a fuel injection pump in which the magnetic valve according to the invention is used, FIG. 2 shows a partial section through FIG. 1 along II-II and FIG. 3 shows a longitudinal section through the magnetic valve according to the invention in an enlarged view.

Description of the embodiment

In the fuel injection pump for multi-cylinder internal combustion engines shown in FIG. 1, a cylinder liner 2 is inserted in a housing 1, in the cylinder bore 3 of which a pump piston 4 is moved back and forth by a drive and cam drive of the fuel injection pump, not shown, at the same time rotating movement is offset, as indicated by the arrows in the drawing. The pump piston 4 includes in the cylinder bore 3 at the end a pump working chamber 6, which is supplied with fuel during the suction stroke of the pump piston via longitudinal grooves 8, which serve as filling grooves, starting from the end face 7 of the pump piston. As can be seen in FIG. 2, which shows a section along line II-II through FIG. 1, the filling grooves 8 are distributed around the circumferential surface of the pump piston at uniform angular intervals. Two grooves are shown in FIG. 2, corresponding to four suction strokes per pump piston revolution for supplying four injection nozzles alternately through this distributor fuel injection pump. During the suction stroke, one of the filling grooves 8 is connected to a suction line 10 which opens laterally into the cylinder bore 3 and which is connected to a pump suction chamber 11 which is enclosed in the housing of the fuel injection pump. The pump suction chamber 11 supplied by a fuel feed pump 12 from a fuel storage container 14 with fuel, which is preferably under pressure dependent on speed, additionally controlled by a pressure control valve 15, which is parallel to the fuel feed pump 12, which is driven in speed synchronism with the fuel injection pump.

The end of the pump piston opposite the pump working chamber 6 protrudes into said pump suction chamber 11 and is connected there to the drive (not shown). An annular slide 17 is slidably arranged on the outer surface of the pump piston, which can be moved in a known manner by a regulator of known design, not shown here, via a regulator lever 18 and thereby controls the outlet opening of a transverse bore 19 in the pump piston. The transverse bore 19 is connected to a longitudinal channel 20 in the pump piston, which enters axially at the end face 7 of the pump piston and ends as a blind bore. A radial bore 21 branches off from this longitudinal channel and leads to a distributor opening, here a distributor groove 22, on the outer surface of the pump piston. At the level of this distributor groove, 3 injection lines 23 branch off from the cylinder bore, each of which leads, for example via a pressure valve, to an injection valve 25. Such injection lines are distributed around the circumference of the cylinder bore 3 in accordance with the number of injection valves to be supplied, in this case four, by the pump piston performing four delivery strokes per revolution.

During the respective suction strokes of the pump piston, it sucks fuel from the pump suction chamber 11 via the filling groove 8, which is then covered with the suction line, so that the pump working chamber 6 is filled with fuel at the beginning of the following delivery stroke. In the load position, the ring slide 17 then closes the outlets of the transverse bore 19 so that during the subsequent delivery stroke of the pump piston and after the filling groove has been closed again in the pump The fuel is brought to high pressure, which is then fed via the longitudinal channel 20 and one of the injection lines 23 to the corresponding fuel injection valve and is injected. To end the high-pressure injection, the transverse bore emerges from the overlap at a stroke predetermined by the ring slide 17, so that the pump working space is now relieved via the longitudinal bore 20 and the transverse bore 19 to the pump suction space, the delivery pressure of the pump piston falls below the opening pressure of the injection valve and thus the high pressure injection is interrupted.

To shut down the internal combustion engine or to end the high-pressure injection, a solenoid valve 27 is also provided in the suction line 10, the closing part 28 of which cooperates with a valve seat 29 designed as a flat seat, on which the closing part 28 engages when the solenoid valve is de-energized by the force of a return spring is coming. The valve seat is located at the transition from a stepped bore part 31 with a small diameter, on the pump work chamber side, to the stepped bore part 30 with a large diameter of a stepped bore, which receives the solenoid valve inserted from the outside. The suction line 10 leads from the step bore part 30 with a large diameter to the pump suction chamber 11. The step bore part 31 with a small diameter opens into a recess 32 in the cylinder sleeve 2, from which a suction line piece 33 with a rectangular cross section opens into the cylinder bore 3 .

The solenoid valve 27 is shown in detail in FIG. 3. In the housing 38 of the solenoid valve, a solenoid 39 and a guide sleeve 40 surrounded by it, into which a magnetic core 41 is immersed, are arranged. An anchor 42, which is loaded by the return spring 43, can be displaced in the guide sleeve 40. The valve housing 38 is on the side of the solenoid valve facing away from the armature closed by a plastic part 44 through which the power supply line 45 leads to the solenoid 39. The space between valve housing 38 and solenoid 39 is filled with a synthetic resin in order to prevent the vibrations transmitted by the internal combustion engine from causing parts of the valve, in particular the electrical connection, to become detached. The core 41 and the armature 42 are conical on the facing end faces in order to obtain a favorable magnetic force transmission for large strokes necessary for the use of the solenoid valve. The armature also serves as a valve part, in which its end projecting out of the guide sleeve 40 into the stepped bore part 30 with a larger diameter is designed as a closing part 28. For this purpose, a hat-shaped cap 47 made of elastic sealing material is vulcanized onto this end of the armature 42, the circumferential outer edge 48 of which rests against the valve seat 29 on the front side when the armature with the closing part 28 with the solenoid coil de-energized by the force of the return spring 43 is brought into the closed position.

The armature 42 has a bore 50 which extends through the end face of the cap 47 coaxially to the stepped bore part 31 and which opens into the receiving bore 53 of large diameter via a conical valve seat 52, which can also be spherical. This receiving bore continues with essentially the same diameter until it emerges at the conically shaped end face of the armature opposite the core 41. In this receiving bore, the return spring 43 is arranged, which is supported on the face on the correspondingly conical core, there on a shoulder, and on the other hand on a sleeve pressed into the receiving bore 53. This sleeve, which can also be fixed in the receiving bore in another way, is to be referred to as an intermediate spring plate 55, since a closing spring 57 is supported on the latter on the other side, which, designed as a compression spring, is attached to it the other end comes to rest on a spring plate 58 which is displaceable within the receiving bore 53. The spring plate has a recess 60 on its end face facing the bore 50, in which a ball 61, which serves as a valve member, is centered. The ball 61, on the other hand, comes to rest in the closed position on the conical valve seat 52 between the receiving bore 53 and the bore 50. The spring plate 58 is advantageously made of plastic and has on the side of the closing spring 57 a pin 63 which projects through a central opening 64 in the intermediate spring plate 55 and is guided there. On its circumference, the intermediate spring plate 55 has recesses 67, so that when the intermediate spring plate or the armature is adjusted, fuel is throttled and the movement cannot flow past the intermediate spring plate. Cross openings 66 branch off from the receiving bore 53, via which the parts of the suction line 10 upstream and downstream of the valve seat 29 are connected when the valve member 61 is lifted off, even when the closing part 28 is in the closed position and via the armature 42 when the closing part 28 is opened the fuel that it displaces can flow off.

The small mass of ball 61 and spring plate 58 with a correspondingly dimensioned closing spring allows a very short hysteresis-poor opening and reclosing of the bore ^* 50 or the connection between the suction line parts. This prevents large amounts of fuel from overflowing from the pump work chamber to equalize the pressure, even if the valve member had been brought into the open position due to momentary pressure surges. In any case, it is prevented that the closing part 28 controlling the substantially larger diameter of the stepped bore part 31 is lifted off its seat. The risk of the internal combustion engine going through is thus reduced. The danger of the internal combustion engine going through exists particularly when the ring slide 17 is displaced towards the pump work space in a very high position and, for. B. is jammed there, so that all or almost all of the fuel that can be delivered by the pump piston arrives from the working area for injection, because only a very small or no residual stroke with relaxation to the pump suction area occurs. Furthermore, there is the danger if, due to the spray adjustment, the delivery stroke of the pump piston is late in relation to its rotational position, so that the filling grooves 8 already at the top dead center of the pump piston or earlier the connection between the pump work chamber and suction line 10 or 31, 32, 33 produce. As a result, fuel enters the recess 32 and the subsequent stepped bore part with a smaller diameter 31 under high pressure, which acts abruptly on the closing part 28 and attempts to lift it off. Due to the storage capacity of the elastic fuel medium, a relatively large amount of fuel can therefore be stored in the space between the cylinder bore 3 and the valve seat 29, in particular when negative pressures are again compensated via the suction line 10 with the closing part 28 open. This stored quantity flows to the pump work space during the following suction stroke, the pressure of the fuel in the recess 32 and adjoining regions 31, 33 and in the pump work space being correspondingly reduced. After closing the Saugleitungsteilstücks 33 through the filling slot a volume of relatively low pressure remains in the area left to the valve seat and a large part of the previously da ^* rin is stored under high pressure fuel enters the pump working space. From this, the fuel can be injected again during the subsequent pressure stroke, in particular if the pump work space cannot be relieved via the ring slide. At the end of the delivery stroke when the suction line section 33 or the subsequent spaces are opened again, the pressure surge can in turn cause the closing portion 28 to open, followed by pressure equalization and a reflow of fuel to the pump work space as previously described. These processes are largely avoided by the solution according to the invention. This ensures that the fuel injection is switched off safely.

Claims

Expectations

1. Solenoid valve, in particular for fuel injection pumps for supplying internal combustion engines with a pump working chamber (6) of the fuel injection pump with a fuel supply source (11) and which can be blocked by the solenoid valve for switching off the fuel injection, during the suction stroke of the pump piston (4) in the direction of the pump working chamber Flowable suction line (10), with a closing part (28) connected to an armature (42) of the solenoid valve, which can be held in the closed position by a return spring (43) on a valve seat (29), from which the suction line (10, 31, 32 , 33) leads to the pump work space (6) and in the closed position is acted upon by the pressure prevailing in the suction line on the pump work space, the closing part having a bore (50) connecting both suction line parts to one another, which is counteracted by a spring (57) against the pressure Valve element acted on in the part of the suction line on the pump work chamber (61) can be closed, characterized in that the valve member is acted upon by a closing spring (57) which is supported in the closing part (28) and the closing part together with the armature (49) can be displaced by the fixedly supporting return spring (43) .

2. Solenoid valve according to claim 1, characterized in that the bore (50) in the closing part (28) is an axial bore which opens via a conical or spherical valve seat (52) into a receiving bore (53) in which the closing member (61) and the closing spring (57) are arranged.

3. Solenoid valve according to claim 2, characterized in that the receiving bore (53) axially penetrates the closing part (28) and the armature (42) and has a fixed intermediate spring plate (55) which on the one hand serves as a base for the fixed core (41) of the magnet of the solenoid valve supporting return spring and on the other hand serves as a base for the closing spring (57).

4. Solenoid valve according to claim 3, characterized in that the valve member (61) is a ball which is supported on a recess (60) in a spring plate (58), which on the other hand has a pin (63) through a central opening ( 64) of the intermediate spring plate (55).

5. Solenoid valve according to claim 4, characterized in that the spring plate is made of plastic.

6. Solenoid valve according to one of claims 3 to 5, characterized gekenn¬ characterized in that the intermediate spring plate (55) is pressed into the receiving bore (53) which is connected via a transverse opening (66) with the suction line (10).