GB2033049A - Device to control injection timing of an injection pump - Google Patents

Abstract

The invention discloses an adjusting device for controlling the injection timing of an injection pump of a fuel-injection internal combustion engine as a function of rotary speed. The device has two fly-weights 11, 12 biassed by springs 13, 14 which are guided between curved surfaces on a guide piece 3a, 4a of a primary part 3, 4 driven by the crankshaft of the engine, and curved surfaces 7, 10 of a secondary part 5, 6 attached to a shaft of the injection pump. The track of the guide piece 3a, 4a is rotatably mounted, and may consist of an outer race 15 of a roller bearing 16, or alternatively of a plain sleeve 17. <IMAGE>

Description

SPECIFICATION Adjusting device to control the injection time of an injection pump of internal-combustion engines The invention relates to an adjusting device to control the injection time of an injection pump of internal-combustion engines, and particularly, but not exclusively, air-compression fuel-injection internal-combustion engines, as a function of the engine rotary speed. An adjusting device is known in which flyweights subject to spring action are guided between curved tracks of a guide piece of a primary part driven by a crankshaft of a guide piece of a secondary part of the adjusting device firmly attached to a pump shaft.

With increasing rotary speed the flyweights of the known adjusting device slide outwards between the curved tracks. Thus the tracks of the primary and secondary part are displaced oppositely in the direction of rotation and in this way an adjustment is obtained between the crankshaft and the injection pump. But the friction which occurs during the sliding causes the flyweights to react sluggishly to a rapid rotary speed variation.

It is the underlying aim of the invention to improve the hysteresis of the known adjusting device, more particularly during rapid rotary speed variations.

According to the present invention there is provided an adjusting device to control injection time of an injection pump of internal combustion engines, as a function of rotary speed, wherein at least one flyweight subject to a resilient bias is guided between curved tracks of a guide piece of a primary part adapted to be driven by an engine crankshaft and of a guide piece of a secondary part of the adjusting device adapted to be attached firmly to a pump shaft, wherein the track of the guide piece of the primary part co-operating with the flyweight is rotatably mounted.

Thus, the flyweights roll both on the track of the secondary part guide piece and on the track of the primary part guide piece. Therefore the flyweights no longer slide as is customary in the case of known adjusting devices, in which the flyweights execute longitudinal movements in addition to the rotary movements.

In a preferred embodiment of the invention, the track is constituted by the outer race of a rolling-contact bearing.

As an alternative, a further embodiment is proposed according to the invention, wherein the track is constituted by a roller mounted rotatably on a bolt.

Two embodiments of the invention will now be described by way of example with reference to the accompanying drawings, in which: Figure 1 shows in cross-section one half of each of the two differently constructed adjusting devices and Figure 2 shows the adjusting devices in a section made along the line Il-Il in Fig. 1.

The two different adjusting devices 1 and 2, only one half of each of which is shown in Figs. 1 and 2, each consist of a primary part 3 or 4 driven by the crankshaft of the internalcombustion engine (not shown) and a secondary part 5 or 6 firmly attached to the pump shaft of the injection pump.

Primary part and secondary part are each provided with two projecting guide pieces 3a, 4a; 5a, 6awhich exhibit curved tracks 7, 8 and 9, 10 respectively, between which cylindrically constructed flyweights 11 and 1 2 respectively are guided which in the case of an increasing rotary speed are urged outwards due to the centrifugal effect and adjust the secondary part with reference to the primary part by a few degrees of angle counter in each case to the force of a return spring 1 3 or 14 arranged between the primary and secondary parts and thus correspondingly modify the injection time.

During this movement the flyweights roll upon both tracks 7, 8 or 9, 10, since the tracks 8 or 9 of the guide pieces 3a or 4a of the respective primary part are rotatably mounted. The track 8 of the guide piece 3a is constituted by the outer race 1 5 of a rollingcontact bearing 1 6 whereas in the other exemplary embodiment the track 9 of the guide piece 4a is constituted by a roller 1 7 which is mounted rotatably on a bolt 1 8.

In Fig. 2, 1 9 or 20 designates the bolt counter-bearing of the primary part.

1. An adjusting device to control the injection time of an injection pump of internalcombustion engines, as a function of rotary speed, wherein at least one flyweight subject to a resilient bias is guided between curved tracks of a guide piece of a primary part adapted to be driven by an engine crankshaft and of a guide piece of a secondary part of the adjusting device adapted to be attached firmly to a pump shaft, wherein the track of the guide piece of the primary part co-operating with the flyweight is rotatably mounted.

2. An adjusting device according to claim 1, wherein the track is constituted by an outer race of a rolling-contact bearing.

3. An adjusting device according to claim 1, wherein the track is constituted by a roller mounted rotatably on a bolt.

4. An adjusting device for controlling the injection timing of an injection pump of a fuel injection internal combustion engine, substantially as described herein with reference to and as illustrated in the accompanying drawings.

**WARNING** end of DESC field may overlap start of CLMS **.

Claims (4)

**WARNING** start of CLMS field may overlap end of DESC **. SPECIFICATION Adjusting device to control the injection time of an injection pump of internal-combustion engines The invention relates to an adjusting device to control the injection time of an injection pump of internal-combustion engines, and particularly, but not exclusively, air-compression fuel-injection internal-combustion engines, as a function of the engine rotary speed. An adjusting device is known in which flyweights subject to spring action are guided between curved tracks of a guide piece of a primary part driven by a crankshaft of a guide piece of a secondary part of the adjusting device firmly attached to a pump shaft. With increasing rotary speed the flyweights of the known adjusting device slide outwards between the curved tracks. Thus the tracks of the primary and secondary part are displaced oppositely in the direction of rotation and in this way an adjustment is obtained between the crankshaft and the injection pump. But the friction which occurs during the sliding causes the flyweights to react sluggishly to a rapid rotary speed variation. It is the underlying aim of the invention to improve the hysteresis of the known adjusting device, more particularly during rapid rotary speed variations. According to the present invention there is provided an adjusting device to control injection time of an injection pump of internal combustion engines, as a function of rotary speed, wherein at least one flyweight subject to a resilient bias is guided between curved tracks of a guide piece of a primary part adapted to be driven by an engine crankshaft and of a guide piece of a secondary part of the adjusting device adapted to be attached firmly to a pump shaft, wherein the track of the guide piece of the primary part co-operating with the flyweight is rotatably mounted. Thus, the flyweights roll both on the track of the secondary part guide piece and on the track of the primary part guide piece. Therefore the flyweights no longer slide as is customary in the case of known adjusting devices, in which the flyweights execute longitudinal movements in addition to the rotary movements. In a preferred embodiment of the invention, the track is constituted by the outer race of a rolling-contact bearing. As an alternative, a further embodiment is proposed according to the invention, wherein the track is constituted by a roller mounted rotatably on a bolt. Two embodiments of the invention will now be described by way of example with reference to the accompanying drawings, in which: Figure 1 shows in cross-section one half of each of the two differently constructed adjusting devices and Figure 2 shows the adjusting devices in a section made along the line Il-Il in Fig. 1. The two different adjusting devices 1 and 2, only one half of each of which is shown in Figs. 1 and 2, each consist of a primary part 3 or 4 driven by the crankshaft of the internalcombustion engine (not shown) and a secondary part 5 or 6 firmly attached to the pump shaft of the injection pump. Primary part and secondary part are each provided with two projecting guide pieces 3a, 4a; 5a, 6awhich exhibit curved tracks 7, 8 and 9, 10 respectively, between which cylindrically constructed flyweights 11 and 1 2 respectively are guided which in the case of an increasing rotary speed are urged outwards due to the centrifugal effect and adjust the secondary part with reference to the primary part by a few degrees of angle counter in each case to the force of a return spring 1 3 or 14 arranged between the primary and secondary parts and thus correspondingly modify the injection time. During this movement the flyweights roll upon both tracks 7, 8 or 9, 10, since the tracks 8 or 9 of the guide pieces 3a or 4a of the respective primary part are rotatably mounted. The track 8 of the guide piece 3a is constituted by the outer race 1 5 of a rollingcontact bearing 1 6 whereas in the other exemplary embodiment the track 9 of the guide piece 4a is constituted by a roller 1 7 which is mounted rotatably on a bolt 1 8. In Fig. 2, 1 9 or 20 designates the bolt counter-bearing of the primary part. CLAIMS

1. An adjusting device to control the injection time of an injection pump of internalcombustion engines, as a function of rotary speed, wherein at least one flyweight subject to a resilient bias is guided between curved tracks of a guide piece of a primary part adapted to be driven by an engine crankshaft and of a guide piece of a secondary part of the adjusting device adapted to be attached firmly to a pump shaft, wherein the track of the guide piece of the primary part co-operating with the flyweight is rotatably mounted.

2. An adjusting device according to claim 1, wherein the track is constituted by an outer race of a rolling-contact bearing.

3. An adjusting device according to claim 1, wherein the track is constituted by a roller mounted rotatably on a bolt.

4. An adjusting device for controlling the injection timing of an injection pump of a fuel injection internal combustion engine, substantially as described herein with reference to and as illustrated in the accompanying drawings.