Mechanical Speed Governor, Provided With an Electronically Controlled Adapting Device, for an Injection Pump of Compression Ignition Internal Combustion Engines

The invention relates to a mechanical speed governor, wherein a stepper or servo motor is provided for correcting the quantity of fuel delivered by a fuel pump in the range of full-load and starting speeds of an internal combustion engine. As control unit is provided to process internal combustion-engine and ambient parameters for controlling the stepper-servo motor, which influences the regulating displacement of a quantity-control member of the injection pump in such a way as to correct the quantity of fuel delivered by an injection pump of compression ignition internal combustion engines provided with an electronically controlled adopting device.

DE 3,430,797 Al discloses a speed governor having an electronically controlled adapting device with which the fuel quantity can be corrected. The delivery quantity of the injection pump can be automatically adapted to the fuel requirement of the internal combustion engine in full-load and starting range in order to reduce (as far as possible) damage to the environment and in particular the emission of hydrocarbons.

An object of the instant invention is to create a speed control on a mechanical speed governor having electronically controlled adaption whose quantity-correction range covers the full-load range of the engine and is also used for control during the starting range. In the event of the electronic system failing in the starting position, the speed control will cover a controllable speed range which does not extend beyond the full-load range

The object is achieved according to the invention by having the electronically controlled adapting device comprises a two-step stop which is in operative connection with the fuel quantity-control member to limit the starting and full-load quantity and wherein the stop can be transferred as a function of speed from a position corresponding to the starting speed into a position corresponding to the full-load speed.

The invention ensures that in the event of a fault in the adapting device in the starting position, the internal combustion engine is not constantly operated with starting quantity at full load and thus at worst destroyed by overheating. Furthermore, despite the emergency-travelling facility, an electronically controlled adaption with small adapting displacements is possible during regular operation of the internal combustion engine. That is no adaption covering the entire range from full load up to starting quantity is necessary, but merely an adaption which covers the full-load range, since when the two-step stop is shifted the adaption also becomes effective for the starting range.

It is further advantageous if the two-step stop is arranged on a transmission lever connected to the stepper-servo motor to interact with a counterstop on the quantity adjusting member. The quantity-adjusting member consists of a control rod and an fork which contains the counterstop and is connected in an articulated manner to the control rod. The counterstop is formed by an adjustable pin. The transmission lever is designed as a pivot mounted strap, which at its free end has two steps arranged to lie one behind the other in the operative direction of the stepper-servo motor. The first stop (limiting the full-load quantity) is effective when the strap is pivoted to the top, and the second stop (limiting the starting quantity) is effective when the strap is pivoted to the bottom.

The strap has a slotted link on which the adjusting member producing the pivoting movement of the strap is guided as a link slide.

The adjusting member is designed as a double-arm lever and is in operative connection with a centrifugal-weight device of the speed governor.

Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawings.

FIG. 1 shows a section through a mechanical speed governor (only partly shown) with adapting device and two-step stop;

FIG. 2 shows another embodiment of the two-step stop, and;

FIG. 3 shows a controlled displacement - speed functional diagram for both exemplary embodiments.

A mechanical speed governor 1 (FIG. 1) is provided as an attachment on a fuel injection pump 2 for compression-ignition internal combustion engines. The fuel pump 2 is constructed as an in-line injection pump and is in operative connection with an electronically controlled adapting device 3 which is composed of a stepper or servo motor 6, controlled by an electronic control unit 4, and fixed to the end face of the governor housing 5. The control unit 4 processes internal-combustion-engine and ambient parameters such as speed, charge-air temperature, charge-air pressure, etc. The servo motor 6, electronically controlled by the control unit 4, has a transmission lever 7 output. The transmission lever 7 projects into the speed governor 1 through housing 5 and is designed as a pivot mounted strap 8 with a free end having a two-step stop 9 arranged thereon. The stop 9 has a first step stop portion 9a limiting the amount of fuel at full-load and a second step stop portion 9b for limiting the amount of fuel during starting. The strap 8 contains a slotted link opening 10 in which an adjusting member 12 is guided as a link slide. The adjusting member 12 is rotatablely mounted in the speed governor 1 and is speed influenced by the governor sleeve 11 of a centrifugal-weight device. This adjusting member 12 is designed as a double-arm lever and produces a pivoting movement of the strap 8 as a function of the speed. In FIG. 1, the adjusting member 12 and the strap 8 are shown in a position corresponding to the starting position. The stop 9a interacts with a counter-stop 13 adjustably fixed to an articulated fork 15 that is articulately connected to the control rod 14 of the injection pump 2. The articulated fork 15 and control rod 14 are parts of the quantity-adjustment member of the fuel Pump 2.

Movement of the control rod 14 to the left adjust the fuel delivery amount of the pump 2. The stops 9(a) and 9 (b) engage the counter stop 13 to stop leftward movement of the control rod 14. The stop 9a acts as a variable stop for limiting the starting displacement of the control rod 14 via the bolt-like counterstop 13, whereas the stop 9b, when the strap 8 is swung up, variably limits the full-load displacement of the control rod 14 via the counter-stop 13.

FIG. 2 shows that the counterstop 13 can be provided on the strap 8 and the two-step stop can be provided on the articulated fork 15. The bolt 16 is of stepped design. Here the step 16a, designed to be smaller in diameter, limits the starting fuel quantity in interaction with the counterstop 13 and the step 16b designed to be larger in diameter, likewise limits the full-load quantity in interaction with the counterstop 13, when the strap 8 is swung up (shown as a broken line).

When the engine is stopped, the strap 8 assumes the position shown in FIG. 1. The control rod 14 is limited in its movement by the starting-quantity stop 9b. After the engine has started (at about 300 rev/min) (see FIG. 3), the adjusting member 12 lifts the strap 7. There the control rod 14 can be adjusted only up to the full-load stop 9a. The distance between the stops 9a and 9b is selected in accordance with the difference in control displacement at full load and at start. In FIG. 3, the adapting displacement at full load is identified by .DELTA.CDFL, and the adapting displacement at start is identified by .DELTA. CDSt Both adapting displacements are the same size and are each effected by the same adapting device. Owing to the small adapting displacements, the adaption can be effected more quickly and the costs can be reduced on account of the use of a smaller stepper motor as a servo motor.

Although the present invention has been described and illustrated in detail, it is to be clearly understood that the same is by way of illustration and example only, and is not to be taken by way of limitation. The spirit and scope of the present invention are to be limited only by the terms of the appended claims.