GB1577260A

GB1577260A - Centrifugal adjuster for internal combustion engines

Info

Publication number: GB1577260A
Application number: GB3928677A
Authority: GB
Original assignee: Diesel Kiki Co Ltd
Current assignee: Bosch Corp
Priority date: 1976-09-21
Filing date: 1977-09-21
Publication date: 1980-10-22
Also published as: FR2365025A1; DE2742268A1; FR2365025B3; JPS5345317U

Description

(54) CENTRIFUGAL ADJUSTER FOR INTERNAL COMBUSTION ENGINES (71) We, DIESEL KIKI Co. LTD., a Japanese Company, of 7-6 Shibuya, 3chome, Shibuya-Ku, Tokyo, Japan, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement: The invention relates to a centrifugal adjuster for internal combustion engines.

A centrifugal adjuster for the speeddependent alteration of the instant of injection in internal combustion engines is known which comprises an arm connected to the camshaft of an injection pump and an adjuster housing in use coupled to the crankshaft of the internal combustion engine. Hinge pins are secured in the housing and serve as pivot bearings for flyweights of the adjuster, and adjuster springs act between the pins and the arm.

In the known automatic centrifugal adjusters the flyweights do not have any further supporting parts besides their pivot bearing and the coupling means with the adjuster part which is to be adjusted.

Because of this and due to unavoidable production errors such as variations in the weight of the flyweights, deviations in the cam path for the adjustment of the commencement of delivery and in the magnitude and strength of the adjuster springs, the commencement of the adjustment of the commencement of delivery does not always occur at the same prescribed speed.

Due to this deviation the prescribed test values for the motor exhaust gases cannot be adhered to and in particular the nitrous oxides content of the exhaust gases deteriorates due to an advancing tendency of the adjustment of the commencement of delivery.

According to the present invention there is provided a centrifugal adjuster for the speed-dependent alteration of the instant of injection in internal combustion engines, the adjuster comprising an outwardly extending member connected to the camshaft of an injection pump and an adjuster housing coupled to the crankshaft of the internal combustion engine, in which housing hinge pins are secured as pivot bearings for flyweights, and adjuster springs act between the pins and the outwardly extending member, the adjuster also comprising stops secured on the adjuster housing for determining an initial position of the outwardly extending member, additional springs being also provded which oppose the adjuster springs during commencement of adjustment of the commencement of fuel delivery.

The centrifugal adjuster in accordance with the present invention avoids by way of comparison the aforementioned disadvantages, and by means of the stop and the arrangement of the additional springs it is advantageously assured that the commencement of the adjustment of the commencement of delivery is kept constant and the characteristic features of the adjustment of the commencement of delivery improved.

The invention will hereinafter be further described by way of example with reference to the accompanying drawing in which: - Fig. 1 is a simplified representation of an automatic centrifugal adjuster in accordance with the present invention shown in a state of rest or in its initial state.

Fig. 2 shows the adjuster of Fig. 1 in operation at high speed, and Fig. 3 is a graph of adjusting angle plotted as a function of engine speed.

In Fig. 1 a pair of hinge pins 2 and stops 3 are in each case rigidly secured to an adjuster housing 1 which is coupled to a drive shaft of the motor that is not shown, and in each case a flyweight 4 is pivotably mounted on the hinge pins. Additional springs 5 which are constructed as compression springs and lie sunk in bores 10 are secured to the front ends 4a, of the flyweights remote from the pins 2, and act in their direction of pressure on the adjacent bearing part 4b of the other flyweight 4 which surrounds the hinge pin 2.

Rollers 6 are secured so as to be freely rotatable, by way of roller pins 9 on the flyweights 4 and each roller bears against a curved edge 8a of an outwardly extending member or arm 8 which is kept in abutting connection with the flyweights 4 by the adjuster springs designated by 7.

The arm 8 is coupled to the cam shaft of the injection pump, the shaft not being shown in the drawing.

Fig. 2 shows the centrifugal adjuster of Fig. 1 in the operational state at high speed and with the flyweights 4 swivelled towards the outside. In this position the flyweights in the known adjusters lie up against either a wall of the housing or a stop which serves to limit the angle of adjustment. In the case of an embodiment of the present invention the stops 3 are so arranged and constructed that they each serve both as a stop for the arm 8 in the initial position of the adjuster as shown in Fig. 1 and as an external stop for the flyweights 4. In Fig.

2 the rollers 6 of the flyweights 4 are supported on the stops 3 and by altering the length of these stops 3 the angle of traverse of the flyweights 4 and thus the maximal angle of adjustment of the centrifugal adjuster can be determined.

In the diagram in Fig. 3 various lines designated by a, b, c, d and e are shown for the behaviour of the angle of adjustment of the commencement of delivery 0 with respect to the speed N which can be achieved by means of the adjuster in accordance with the invention.

The following now describes in more detail the mode of operation of the centrifugal adjuster described with regard to Figs. 1 and 2.

In Fig. 1 the arm 8 which is coupled to the cam shaft of the injection pump abuts the stops 3 which are secured on the adjuster housing 1 due to the compressive force of the adjuster springs and the initial position of the adjuster parts is in this way accurately determined prior to the commencement of adjustment. Instabilities which are derived from errors in individual adjuster parts are thus excluded during the commencement of adjustment. A free movement of the flyweights 4 is furthermore prevented by means of the additional springs 5 so that the feared "rattling" of the flyweights at low speed is avoided.

From the moment at which the automatic adjustment of the commencement of delivery is initiated, the flyweights 4 are moved outwards in the direction of the external diameter of the adjuster housing 1 due to the rising centrifugal force at increasing speed and the rollers 6 simultaneously cause the arm 8 to to rotate in a clockwise direction.

The spring constant which acts on the arm 8 diminishes due to the additional springs 5 which oppose the adjuster springs 7 and adjustment characteristics are aimed for as shown by the entirety of the line a in Fig. 3. It can be seen from Fig. 3 that the commencement of the adjustment of the commencement of delivery in the case of line a proceeds at a steeper rate than in the case of the characteristics hitherto usual which are represented in Fig. 3 by a dotted line e. This correction corresponding to the line a which is effected in accordance with the invention leads to precise operation of the adjuster and the commencement of adjustment can be coordinated very accurately with a predetermined engine speed.

By altering the position of the stops 3 the adjustment lines b and c shown in Fig.

3 by dash-dot lines can be aimed for and by an appropriate choice of the spring constants as well as the relaxed lengths of the additional springs 5 and the adjusting springs 7 yet further line characteristics and adjustment angles are possible, as t.g.

shown by the dash-dot line d. In the case of the halt in adjustment which can be aimed for in line characteristic d, additional springs 5 which are pretensioned in a known manner, are required, but are not shown.

The present invention achieves a reduction of instability which is caused by production errors in the adjuster parts during the commencement of the adjustment of the commencement of delivery as well as an increase in efficiency during the commencement of adjustment by means of the stops 3 which limit the angle of rotation of the arm 8 and the additional springs 5 which oppose the adjuster springs 7.

Furthermore it is possible to achieve an improved adaptation of the adjustment curves to the process of commencement of ignition found to be the most favourable for the engine.

WHAT WE CLAIM IS: - 1. A centrifugal adjuster for the speeddependent alteration of the instant of injection in internal combustion engines, the adjuster comprising an outwardly extending member connected to the camshaft of an injection pump and an adjuster housing coupled to the crankshaft of the internal combustion engine, in which housing hinge pins are secured as pivot bearings for flyweights, and adjuster springs act between the pins and the outwardly extending member, the adjuster also comprising stops secured on the adjuster housing for determining an initial position of the outwardly extending member, additional springs being also provided which oppose the adjuster springs during commencement of adjustment of the commencement of fuel delivery.

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

Claims

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

rotatable, by way of roller pins 9 on the flyweights 4 and each roller bears against a curved edge 8a of an outwardly extending member or arm 8 which is kept in abutting connection with the flyweights 4 by the adjuster springs designated by 7.

The arm 8 is coupled to the cam shaft of the injection pump, the shaft not being shown in the drawing.

Fig. 2 shows the centrifugal adjuster of Fig. 1 in the operational state at high speed and with the flyweights 4 swivelled towards the outside. In this position the flyweights in the known adjusters lie up against either a wall of the housing or a stop which serves to limit the angle of adjustment. In the case of an embodiment of the present invention the stops 3 are so arranged and constructed that they each serve both as a stop for the arm 8 in the initial position of the adjuster as shown in Fig. 1 and as an external stop for the flyweights 4. In Fig.

2 the rollers 6 of the flyweights 4 are supported on the stops 3 and by altering the length of these stops 3 the angle of traverse of the flyweights 4 and thus the maximal angle of adjustment of the centrifugal adjuster can be determined.

In the diagram in Fig. 3 various lines designated by a, b, c, d and e are shown for the behaviour of the angle of adjustment of the commencement of delivery 0 with respect to the speed N which can be achieved by means of the adjuster in accordance with the invention.

The following now describes in more detail the mode of operation of the centrifugal adjuster described with regard to Figs. 1 and 2.

In Fig. 1 the arm 8 which is coupled to the cam shaft of the injection pump abuts the stops 3 which are secured on the adjuster housing 1 due to the compressive force of the adjuster springs and the initial position of the adjuster parts is in this way accurately determined prior to the commencement of adjustment. Instabilities which are derived from errors in individual adjuster parts are thus excluded during the commencement of adjustment. A free movement of the flyweights 4 is furthermore prevented by means of the additional springs 5 so that the feared "rattling" of the flyweights at low speed is avoided.

From the moment at which the automatic adjustment of the commencement of delivery is initiated, the flyweights 4 are moved outwards in the direction of the external diameter of the adjuster housing 1 due to the rising centrifugal force at increasing speed and the rollers 6 simultaneously cause the arm 8 to to rotate in a clockwise direction.

The spring constant which acts on the arm 8 diminishes due to the additional springs 5 which oppose the adjuster springs 7 and adjustment characteristics are aimed for as shown by the entirety of the line a in Fig. 3. It can be seen from Fig. 3 that the commencement of the adjustment of the commencement of delivery in the case of line a proceeds at a steeper rate than in the case of the characteristics hitherto usual which are represented in Fig. 3 by a dotted line e. This correction corresponding to the line a which is effected in accordance with the invention leads to precise operation of the adjuster and the commencement of adjustment can be coordinated very accurately with a predetermined engine speed.

By altering the position of the stops 3 the adjustment lines b and c shown in Fig.

3 by dash-dot lines can be aimed for and by an appropriate choice of the spring constants as well as the relaxed lengths of the additional springs 5 and the adjusting springs 7 yet further line characteristics and adjustment angles are possible, as t.g.

shown by the dash-dot line d. In the case of the halt in adjustment which can be aimed for in line characteristic d, additional springs 5 which are pretensioned in a known manner, are required, but are not shown.

The present invention achieves a reduction of instability which is caused by production errors in the adjuster parts during the commencement of the adjustment of the commencement of delivery as well as an increase in efficiency during the commencement of adjustment by means of the stops 3 which limit the angle of rotation of the arm 8 and the additional springs 5 which oppose the adjuster springs 7.

Furthermore it is possible to achieve an improved adaptation of the adjustment curves to the process of commencement of ignition found to be the most favourable for the engine.

WHAT WE CLAIM IS: - 1. A centrifugal adjuster for the speeddependent alteration of the instant of injection in internal combustion engines, the adjuster comprising an outwardly extending member connected to the camshaft of an injection pump and an adjuster housing coupled to the crankshaft of the internal combustion engine, in which housing hinge pins are secured as pivot bearings for flyweights, and adjuster springs act between the pins and the outwardly extending member, the adjuster also comprising stops secured on the adjuster housing for determining an initial position of the outwardly extending member, additional springs being also provided which oppose the adjuster springs during commencement of adjustment of the commencement of fuel delivery.
2. A centrifugal adjuster as claimed in

Claim 1, in which the additional springs comprise compression springs secured at that end of the flyweights remote from the hinge pin and when the adjuster is at rest said springs abut against a part which is connected at least indirectly with the adjuster housing.
3. A centrifugal adjuster as claimed in Claim 2 in which the additional springs abut against the bearing part of the adjacent flyweight.
4. A centrifugal adjuster as claimed in any of Claims 1 to 3, in which the additional springs are set into a bore in each of the flyweights.
5. A centrifugal adjuster as claimed in any of Claims 1 to 4, in which a pretensioned spring serves as additional spring.
6. A centrifugal adjuster as claimed in any preceding claim in which the stops are secured in the adjuster housing in such a manner that their length and/or position can be adjusted.
7. A centrifugal adjuster constructed and adapted to operate substantially as hereinbefore particularly described with reference to and as illustrated in the accompanying drawing.