摘要:
A fuel injection pump for internal combustion engines in which by means of an obliquely extending control groove on the jacket face of a distributor, the end of injection can be varied by opening a relief conduit during the displacement of the distributor. The injection onset is made to follow this variable end of injection by providing that the stroke position of the pump pistons of the fuel injection pump is ascertained at the end of injection by a transducer, by means of which at the same time a metering duration of a magnetic valve that has already been opened at the time of the end of the injection stroke is controlled. In this manner, with a radial piston pump so embodied, the opportunity is afforded of accurately adjusting the quantity of fuel to be metered by means of a magnetic valve, even with variable injection times. All that needs to be done is that the magnetic valve be closed exactly and rapidly at the end of metering, while an error in opening on the part of the magnetic valve does not occur. In this manner, a very precise metering of the fuel to be injected is attained with simple means.
摘要:
A fuel injection apparatus (FIG. 1) for internal combustion engines is proposed, in which the onset and end of injection are determined by means of a hydraulically actuated control slide. The injection pumps of the apparatus, preferably combined with an injection nozzle to make a pump/nozzle unit, have a central control fuel source represented by a supply pump and a first pressure limitation valve, which generates a control pressure (p.sub.S) actuating the control slide which is several times greater than the supply pressure (p.sub.V) determined by a second pressure limitation valve. In order to initiate the onset of injection, the control slide is placed under control pressure (p.sub.S) by a valve assembly via a distributor apparatus and closes an overflow channel leading out of the pump work chamber. In order to control the end of injection, the control slide during its return stroke again relieves this overflow channel toward a low-pressure line. The control pressure (p.sub.S) in the control pressure line required for actuating the stroke movement of the control slide is established by means of blocking the outflow out of this line by means of the valve assembly.
摘要:
A fuel injection apparatus for internal combustion engines is proposed (FIG. 1), in which the onset and end of injection are determined by a hydraulically actuated control slide. The injection pumps of the apparatus, which are preferably combined with an injection nozzle to make a pump/nozzle unit, having a central magnetic valve assembly comprising two magnetic valves switched hydraulically in parallel, which valve assembly is inserted in a connection between a control pressure line, which can be placed under control pressure (P.sub.S) from a source of control fuel, and a low-pressure line which is under supply pressure (P.sub.V). In order to initiate the onset of injection, the control slide is placed under control pressure (P.sub.S) by the valve assembly via a distributor apparatus and closes an overflow channel leading out of the pump work chamber. In order to control the end of the injection, the control slide, during its return stroke, relieves this overflow channel toward a low-pressure line. The control pressure (P.sub.S) in the control pressure line required for actuation of the stroke movement of the control slide is built up by means of the valve assembly as a result of blocking the outflow from this line.
摘要:
A fuel injection apparatus for internal combustion engines in which beyond a predetermined remaining stroke during the supply stroke of the pump piston, a relief conduit is opened via a control edge. The same control edge closes the relief conduit once again during the intake stroke. During the subsequent effective intake stroke, the quantity of fuel to be injected upon the following compression stroke is metered by means of the electrically actuatable valve. The magnetic valve here is already opened before the closure of the relief conduit by the control edge, so that in the opening phase of the relief conduit, the pump work chamber of the fuel injection apparatus is flushed. In this manner, precise metering of the quantity of fuel to be injected is attained.
摘要:
In the method according to the invention, the inlet pressure and the inlet cross section of the fuel pre-stored in the pump work chamber is constant, and it is solely the opening duration of an inlet valve which is electrically regulated. In addition, a shift in the instant of supply onset controlled in accordance with operating characteristics is attained by means of a variation in the return-flow fuel quantity. A shift in the instant of supply onset, which is undesired when there is a change in the quantity of fuel to be injected, is prevented by means of a simultaneously-effected correction of the return-flow fuel quantity. A fuel injection apparatus suitable for performing the method has, as the inlet valve, a magnetic valve which determines the quantity of fuel pre-stored in the pump work chamber. The rotary position of the pump piston is variable in order to shift or correct the instant of supply onset by means of an adjacent device actuated by an electromechanical adjustment element. An electric control device emitting the metering pulse and a control pulse is connected with a set-point transducer and an adjustment-path transducer of the adjustment device. The apparatus can be equipped with either a pump/nozzle or a normal piston injection pump supplying the injection nozzle via a pressure line, or with a distributor injection pump.
摘要:
A fuel injection apparatus for internal combustion engines, which includes a pump piston guided in a cylinder bore driven to reciprocate axially by a cam drive. With a face end, the pump piston defines a pump work chamber, which communicates with an injection valve via a pressure conduit and which is supplied with fuel and relieved via a fuel line. Supply onset and supply end are controllable via a feed pump and a magnet valve are disposed in the fuel line, which communicates with a fuel supply vessel (33) to control supply onset and end of supply. In order to relieve a pressure of the high-pressure chambers, especially at high engine speeds, a fuel tapping device, which is controllable as a function of pressure is connected to a relief line that branches off from the fuel line.
摘要:
A fuel injection pump for internal combustion engines for controlling the fuel quantity with an electric closed-loop control device, which controls an electric positioner, which in turn actuates an element that determines the fuel injection quantity per pump piston supply stroke. The supply of fuel to the pump work chamber is effected via a fuel supply line, in which an adjustable throttle is disposed. The throttle is actuated in accordance with the position of a gas pedal, but it controls an increasingly larger through cross section of the fuel supply line than would correspond to the fuel metering by the closed-loop control device. A minimum through cross section is defined by a fixed throttle. With this apparatus, emergency operation if the electric control system for the fuel injection quantity fails can be attained, without the apparatus for emergency operation interfering with fuel metering by the closed-loop control device. In particular, the fixed throttle prevents racing of the engine counter to the intentions of the driver in the event that the closed-loop control system fails.
摘要:
Fuel injection nozzle for internal combustion engines includes a first closing spring which acts continuously on the valve needle by means of a central pressure pin and, in addition, a second closing spring which acts continuously on the valve needle by means of a pressure piece after covering the distance of an initial stroke. The pressure piece is supported at the nozzle body by means of an intermediate bush during the initial stroke. The initial stroke is limited by means of the shoulders at the valve needle and the intermediate bush, whereas the total stroke is limited by means of the shoulders at the intermediate bush and the intermediate disk. Accordingly, the initial stroke can be adjusted very accurately to a desired magnitude merely by means of grinding the valve needle and does not change during the assembly of the injection nozzle.
摘要:
A fuel injection pump for internal combustion engines, in which beyond a predetermined remnant stroke during the supply stroke of the pump piston a relief conduit is opened via a first control edge and the remaining fuel pumped by the pump piston is pumped into a reservoir connected there. During the subsequent intake stroke, the diverted fuel is pumped back into the pump work chamber of the pump piston, until the first control edge again closes the relief conduit. During the subsequent intake stroke of the pump piston, in particular at the bottom dead center position of the pump piston, the relief conduit to the reservoir is once again opened by a second control edge, and then a complete relief of the reservoir is attained. It is during this phase that the metering of the fuel to be injected during the next supply stroke of the pump piston also takes place, via a magnetic valve. With an apparatus of this kind, it is advantageous that the fuel quantity per supply stroke of the pump piston that is actually to be injected can be metered exactly by means of a magnetic valve under pressure conditions that remain constant despite variable opening times.
摘要:
A fuel injection pump in which the quantity adjustment member has a travel limitation in the form of an adjustable stop, which is adjusted in accordance with the displacement of an adjusting piston in accordance with a contour defined on the adjusting piston. The displacement of the adjusting piston is effected with the rpm-dependent pressure of the suction chamber of the fuel injection pump, and the work chamber preceding the adjusting piston can be uncoupled from the suction chamber via a throttle. The maximum displacement of the adjusting piston is limited by a stop which is adjustable in accordance with charge pressure or by a pressure control device by means of which the pressure in the work chamber can be adjusted or limited.