GB2033009A

GB2033009A - A speed governor for fuel injection pumps

Info

Publication number: GB2033009A
Application number: GB7935435A
Authority: GB
Original assignee: Robert Bosch GmbH
Current assignee: Robert Bosch GmbH
Priority date: 1978-10-14
Filing date: 1979-10-12
Publication date: 1980-05-14
Also published as: JPS5554641A; GB2033009B; FR2438747A1; FR2438747B1; DE2844911A1

Abstract

To make the extra fuel delivered for starting dependent upon temperature, a temperature dependent transducer (33) actuates a lever (31), an end of which constitutes a movable stop (30) which acts on a starting lever (22) to determine the starting quantity, which quantity is reduced as the temperature increases. <IMAGE>

Description

SPECIFICATION A speed governor for fuel injection pumps This invention concerns a speed governor for fuel injection pumps.

A known speed governor for fuel injection pumps for internal combustion engines, has a starting lever, one end of which is coupled to a fuel delivery adjustment member of the injection pump, and whose other end is subjected to engine-speed-dependent forces of a speed transducer, against the force of a spring, whereby a fuel increment, for starting, is metered by the adjusting member when in its initial position, which increment is reduced by the speed governor, following starting, at least to the full-load quantity.

In this known speed governor a fuel increment, for starting, is delivered even when the internal combustion engine is warm. However, as is known, the fuel increment required in order to ensure the true running of the engine is strongly dependent upon the engine temperature. Thus, a cold engine requires a substantially larger increment than a warm engine; in fact, the latter may even start better almost without an increment. Apart from the fact that delivery of a starting increment in order to start a warm engine means a needless consumption of fuel, the noxious constituents of the exhaust emission during this phase are relatively substantial, and there is the added danger of sooting of the glow plug in the combustion chamber.

In accordance with the present invention there is provided a speed governor for a fuel injection pump for an internal combustion engine, having a starting lever, one end of which is coupled to a fuel delivery adjustment member of the injection pump, and whose other end is subjected to engine-speed-dependent forces of a speed transducer, against the force of a spring, whereby an excess fuel quantity for starting, is metered by the adjusting member when in its initial position, the fuel quantity being reduced by the speed governor, following starting, at least to the normal full-load quantity, there being provided an adjustable stop which acts upon the starting lever and, via an element which operates in dependence upon temperature, reduces the excess starting quantity as the temperature rises.

The speed regulator according to the present invention, has the advantage that, for warm starting, a fuel increment only just sufficient to maintain true running is injected.

A preferred embodiment of the invention has the advantage that it is possible, for warm starting, to maintain the fuel increment only just sufficient to compensate for leakages which may occur when the engine is hot.

The present invention will now be described further by way of example only with reference to the accompanying drawing, in which: Figure 1 shows, as a first embodiment, a stop operated by an expansion-type control element, and Figure 2 shows, as a second embodiment, a bimetallic stop.

In a housing 1 of a fuel injection pump there is arranged a bush 2, in whose internal bore a pump piston 3, driven by a cam drive mechanism 4, performs a simultaneous reciprocating and rotary motion. A pump working chamber 5 of this pump is supplied with fuel, from a slightly pressurised suction chamber 8, while the pump piston 3 is performing its suction stroke or is in its bottom dead centre position, via longitudinal grooves 6, which are arranged in the periphery of the pump piston 3 and which communicate with the pump working chamber 5, and an intake port 7, which extends inside the housing 1 and the bush 2.When, at the commencement of the injection stroke, and following a corresponding angular displacement of the pump piston 3, the intake port 7 is separated from the longitudinal grooves 6, the fuel present in the pump working chamber 5 is fed via a delivery passage 9, arranged in the pump piston 3, and a longitudinal distributing groove 10 to delivery lines 11, which are distributed about the pump piston 3 in the housing 1 and the bush 2, and whose number corresponds to the number of cylinders of the internal combustion engine to which fuel is to be delivered. A pressure relief valve 1 2 is provided in each of the delivery lines 11. The delivery passage 9 has a transverse bore 13, which communicates with the periphery of the piston 3.This transverse bore is controlled by an axially displaceable annular valve slide 14, for deteriming the amount of fuel to be delivered.

When the pump piston 3 has performed a certain stroke, namely, the actual injection stroke, the transverse bore 1 3 emerges from the valve slide 14, so that fuel is able to flow from the pump working chamber 5 back to the suction chamber 8. The higher the arrangement of the valve slide 1 4 shown in the drawing, that is, the closer it is moved to the bush 2, the greater the amount of fuel delivered by the injection pump of the internal combustion engine. The position of the valve slide 1 4 shown in the drawing is for maximum fuel delivery, such as is necessary for starting a cold internal combustion engine.

Another position, which the valve slide occupies when no fuel delivery is required, is shown by broken lines.

The speed regulator, which, in these embodiments, is integrally formed with the housing 1 of the fuel injection pump, incorporates a speed transducer or speed signal generator 16, which acts upon levers connected by one of their ends to the valve slide 14, and, by their other ends, to a regulating spring 17, the loading of which is arbitrarily variable by means of an adjusting lever 1 8. The speed transducer 16, which is actuated via toothed gears 19, comprises flyweights 20, which act upon an adjusting sleeve 21, which, in its turn, acts upon a starting lever 22. The starting lever 22 is connected via a ball-and-socket joint 23 to the valve slide 14, and is pivoted on a spindle 24, which serves as the spindle of a one-armed regulating lever 25.Between the starting lever 22 and the regulating lever 25 there is arranged a starting spring 26, which, when the regulator, that is, the adjusting sleeve 21, is in its neutral state illustrated, pushes the two levers 22 and 25 apart and thereby displaces the valve slide 14 to a position in which a starting increment is delivered to the internal combustion engine.

When, after the engine has started, and because of the engine speed then attained, the adjusting sleeve 21 has pushed the starting lever 22 against a stop 27 on the regulating lever, whereby the starting spring 26 is compressed, the valve slide 14 takes up its fullload operating position, which is defined by a stop 28. When the adjusting lever 1 8 is then moved to a reduced-load position, that is, for delivering a reduced amount of fuel for injection, as, for example, in its idling position, the regulating spring 17 correspondingly releases the pressure on the regulating lever 25, so that the valve slide is displaced to a corresponding lower position. The idling speed is then regulated by means of an idling spring 29, which is weaker than the regulating spring 17.The amount of fuel injected in each case, that is, the position of the valve slide 14, corresponds then to the engine speed given by the speed transducer 16, and also to the load given by the adjusting lever 18.

The initial position of the starting lever 22 is determined by a stop 30, which is adjustable from outside the pump by means of a lever 31. Thus, by means of this lever 31, the stop 30 may be displaced so far upwards that, because of the resultant displacement of the starting lever and the regulating lever, the valve slide 14 is moved downwards to a position in which the delivery of fuel to the internal combustion engine is interrupted, that is, the engine is stopped.

According to the first embodiment of the invention, shown in Fig. 1, this lever 31 may be acted upon by a thermostatic positioning element 32, which operates in dependence upon the temperature of the cooling water of the engine, or the temperature of the injection pump. In the embodiment illustrated, an expansion-type control element 33 is exposed to the cooling water 34 of the internal combustion engine, and, via, a Bowden cable arrangement 35, displaces a stop 36 for the lever 31. The stop 36 is provided, for example, with a slot 37, so that, independently of the thermostatically controlled imitial position of the stop 30, the engine may be stopped either by means of the latter, or by the lever 31.The higher the engine temperature, the farther the stop 36 is displaced downwards, and the higher the stop 30, for the starting lever 22, is pushed upwards, whereby the valve slide 14 is shifted to a position for delivery of a reduced starting increment.

When the internal combustion engine is warm, the stop 30 is pushed so far upwards that the lever 22 is directly in abutment, or almost in abutment, with the regulating lever 25.

According to the second embodiment, shown in Fig. 2, in which components corresponding to the first embodiment are designated by identical reference numerals, but with an attached index mark, a bimetallic member 38, which is bent round the starting lever, is attached to the regulating lever 25' in order to serve as a stop. In the position shown, this bimetallic member is heated by the temperature of the fuel, and abuts a pin 39, which limits the possible displacement of the bimetallic member. Another position of the bimetallic member, which permits optimal relative movement of the starting lever 22', and which corresponds to a cold engine, is shown by broken lines. According to the temperature, the possible displacement of the starting lever 22', and, correspondingly, the fuel increment for starting, are reduced by varying amounts. The position of the starting lever 22', shown by broken lines, corresponds to the neutral position prior to starting with a warm engine. Thus, a small fuel increment is delivered, which serves to compensate for leakages, and not to provide additional fuel for starting. The bimetallic member 38 may, of course, be heated electrically instead of by the fuel.

Claims

1. A speed governor for a fuel injection pump for an internal combustion engine, having a starting lever, one end of which is coupled to a fuel delivery adjustment member of the injection pump, and whose other end is subjected to engine-speed-dependent forces of a speed transducer, against the force of a spring, whereby an excess fuel quantity for starting, is metered by the adjusting member when in its initial position, the fuel quantity being reduced by the speed governor, following starting, at least to the normal full-load quantity, there being provided an adjustable stop which acts upon the starting lever and, via an element which operates in dependence upon temperature, reduces the excess starting quantity as the temperature rises.

2. A speed governor as claimed in claim 1, in which a regulating lever and the starting lever have a common pivot point, the regulating lever being subject to the arbitrarily variable force of a regulating spring which is taken in train, in the manner of a drag link, by the starting lever on completion of the starting displacement.

3. A speed governor as claimed in claim 1 or 2, in which the stop is adjustable by means of a bimetallic member.

4. A speed governor as claimed in claim 2 or 3, in which the element which operates in dependence upon temperature is attached to the regulator lever and its displacement is limited by a pin.

5. A speed governor as claimed in claim 1 or 2, in which an expansion-type control element which operates in dependence upon the temperature of the cooling water of the internal combustion engine, serves as the temperature-dependent element.

6. A speed governor as claimed in claim 5, in which the adjustable stop may be arbitrarily displaceably applied in order to stop the delivery of fuel to the internal combustion engine.

7. A speed governor constructed and arranged substantially as hereinbefore described with reference to and as illustrated in the accompanying drawings.