CS204986B2 - Combustion engine with injection pump - Google Patents

Abstract

1458995 Fuel injection pumps SOC D ETUDES DE MACHINES THERMIQUES 26 June 1974 [26 June 1973] 28324/74 Heading F1A A fuel injection pump has an intermediate member 6 dividing the space between the pumping plunger 12 and a tappet 3 into chambers 8, 9, the chamber 9 being pressurizable with gas in order to stop the pump by moving the plunger 12 away from contact, via the intermediate member 6, with the tappet 3. A device 16 sensitive to overspeeding of the engine supplied by the pump controls the supply of gas from a source 15 through a fuel leakage recovery duct 10 to the chamber 9. The chamber 8 is provided with a breather or valve 17, the latter being either located in the pump body 7 or the member 6. The breather or valve prevents pressure building up in the chamber 8 due to leakage past the intermediate member 6. A plunger return spring 13 maintains the intermediate member in contact with the tappet during normal operation.

Description

BACKGROUND OF THE INVENTION The present invention relates to an apparatus for stopping an internal combustion engine with fuel injection in the event of an increase in engine speed, the engine being equipped with an in-line injection pump with reciprocating pistons with a constant stroke.

Devices are known in which, when the engine speed of an internal combustion engine with fuel injection is increased, a speed-sensitive interrupter opens a valve supplying a pressure medium to the hydraulic servomotors, their pistons acting on the racks controlling the injection pumps to reduce fuel injections or interrupt injection molding. The disadvantage of these arrangements is that they cannot act during accidental blocking of the rack or in case of failure of the mechanical connection of the servomotors and the rack.

There are also known devices for stopping the injection pumps by hydraulic servomotors, each of which is mounted on one injection pump, the working cylinders of these servomotors being supplied with a pressurized environment allowing the piston of each working cylinder to be moved and transmitted to the injection pump piston levers to move the injection pump piston away from its tappet and its associated cam.

This device has the disadvantage of complex construction and high production costs.

SUMMARY OF THE INVENTION It is an object of the present invention to provide an apparatus for stopping injection pumps in the event of an increase in the speed of an internal combustion engine which is simple, reliable, low cost and which eliminates all the disadvantages of the known apparatus.

The above drawbacks are overcome by the internal combustion engine with at least one constant-stroke reciprocating piston, in which the guide piston moving in the pump housing, located between the injection piston and its actuating tappet, forms two closed and separate chambers in the pump housing, wherein the upper chamber comprises an injection piston and the lower chamber a tappet according to the invention, characterized in that the means for supplying a pressurized gaseous medium are connected to the lower chambers of the injection pump.

Further, according to the invention, the means for supplying a pressurized gaseous medium comprises a source of, for example, compressed air and an interrupter sensitive to an increase in the engine speed.

Finally, according to the invention, the upper chamber of the injection pump is provided with means for communicating with the ambient atmosphere, for example a safety valve or slots of a control gear.

According to the invention, a pressure medium such as air or inert gas such as nitrogen or carbon dioxide is supplied to the interior of the injection pump housing such that the pressure of the environment acts on the sliding portion between the injection pump piston and its actuating tappet to move the pistons away tappets and fuel injection interruptions.

An advantage of the device according to the invention is a substantially simplified modification over the prior art devices, since it does not comprise separate servomotors with working cylinders intended to control the racks or levers to move the pistons of the injection pumps from the respective actuating tappets.

An example of a device according to the invention will be further described with reference to the accompanying drawings, showing a partial front view of an injection pump with a treatment according to the invention.

As can be seen from the drawing, the device comprises an injection pump 1 with a reciprocating piston 12 of constant stroke. The piston 12 is moved by the action of a tappet 3, pulled by a roller 4, resting on the cam

In the pump body 7, a guide piston 6 is displaceably mounted between the injection piston 12 and its actuating tappet 3. The guide piston 6 defines two closed separate chambers 8, 9 in the pump body 7, of which the upper chamber 8 comprises the injection piston 12. and the lower chamber 9 comprises a tappet 3. The lower chamber 9 is provided at the lower part with a channel 10 for recovering fuel leakage.

In addition to the vertical reciprocating movement, the injection piston 12 is also rotated about a vertical axis, a control gear 11 and a pinion 2 for controlling the amount of fuel injected in a known manner.

There may be a blockage of the toothed rack 11 in a position corresponding to the maximum amount of fuel injected, for various reasons, for example due to seizure or impurities. Then the engine starts and must be stopped quickly by stopping the fuel supply. For this purpose, according to the invention, a pressurized gaseous medium, for example inert, nitrogen or carbon dioxide, is supplied to a lower chamber 9 comprising a tappet 3, the pressurized medium having a pressure to overcome the force of the return spring 13 of the injection piston 12 and 6 of the piston 12 from the tappet 3, so that fuel is no longer injected into the engine, which consequently stops.

The supply of the pressurized gaseous medium to the lower chamber 9 is very simply made by a leakage passage 10, which communicates with a source 15, for example of compressed air, controlled by an interrupter 16 sensitive to an increase in engine speed.

The upper chamber 8, comprising the injection piston 12, is provided with a means which connects the upper chamber 8 to the external atmosphere and is designed, for example, as a safety valve 17, a non-return valve or a simple venting port to prevent high pressure in the upper chamber 8 from leaking. gaseous medium from the lower chamber 9 to the upper chamber 8. This prevents the introduction of impurities into the space of the rack 11 or the clogging of this space by the escaping fuel which is pushed to the rack 11 by the pressure in the upper chamber 8.

The device according to the invention is therefore substantially simplified over the prior art, and its function is much more reliable.

Thus, the guide piston 6 may be provided without openings connecting the upper chamber 8 to the lower chamber 9 as shown in the drawing, or the guide piston 6 may be provided with openings which pass through it and form a connection between the upper chamber 8 and the lower chamber 8. The apertures are provided with flaps which allow the pressurized gaseous medium to pass only from the upper chamber 8 to the lower chamber 9, making the invention easy to use with the prior art injection pumps.

The invention is not limited to the embodiment described and illustrated, which has been exemplified. The invention may comprise all means constituting technical variations of the described means, as well as combinations thereof, provided that they are made according to the spirit of the invention and do not go beyond the scope of the invention.

Claims (3)

OBJECT OF THE INVENTION An internal combustion engine with an injection pump having at least one constant-stroke reciprocating piston, in which the guide piston moving in the pump housing, located between the injection piston and its actuating tappet, forms two closed and separate chambers in the pump housing, the upper chamber comprises an injection piston and the lower chamber a tappet, characterized in that means for supplying a pressurized gaseous medium are connected to the lower chambers (9) of the injection pump (1) via a channel (10). An internal combustion engine according to claim 1, characterized in that the means for supplying the pressurized gaseous medium comprises a source (15), for example compressed air, and an interrupter (16) sensitive to increasing the engine speed. Internal combustion engine according to claim 1 or 2, characterized in that the upper chamber (8) of the injection pump (1) is provided with means for communicating with the ambient atmosphere, for example a safety valve (17) or grooves of the control gear (11).