GB2035621A

GB2035621A - Improvements in speed governors for fuel injection pumps

Info

Publication number: GB2035621A
Application number: GB7937567A
Authority: GB
Original assignee: Robert Bosch GmbH
Current assignee: Robert Bosch GmbH
Priority date: 1978-10-31
Filing date: 1979-10-30
Publication date: 1980-06-18
Also published as: GB2035621B; JPS6316575B2; DE2847248C2; DE2847248A1; JPS5560629A

Abstract

The travel of the output member (9) of a centrifugal speed signal generator (2) is measured by a transducer (10) and an electronic control device (not shown) energises an electromagnet (18) accordingly to adjust the pivot point (16a) of a governor lever (3) via which the governor sleeve (15) acts on a fuel quantity regulating member (5). A second transducer (24) feeds back to the control device the position of the armature (19) of the electro-magnet. <IMAGE>

Description

SPECIFICATION Improvements in speed governors for fuel injection pumps The invention relates to speed governors for fuel injection pumps.

The increasing demands on the quality of regulation of a speed governor, particularly when an isostatic governor having a particularly low degree of proportionality is involved, render it necessary to provide electrically controlled modulation of the speed governor or to intervene electrically in the governor. One of the pre-requisites for realising intervention of this type is a suitable and particularly inexpensive transducer. By way of example, transducers operating predominantly with electronic means are used for measuring rotational speed. On the one hand, these transducers are relatively expensive and, on the other hand, they require an electronic control device for processing the measured values.

The present invention provides a speed governor for a fuel injection pump having a centrifugal speed signal generator which is driven proportionally to the speed of the pump and which has fly-weights which actuate an adjusting member against at least one restoring force, a fuel quantity regulating member being displaceable by means of the adjusting member and a linear transducer for measuring the travel ofthe adjusting member.

This has the advantage that the actual adjusting movement of the centrifugal speed signal generator is measured in addition to the rotational speed, this being done in a transducer whose construction and function are extremely simple and which is manufacturable in a particularly inexpensive manner. A linear transducer of this kind can also be accommodated in a spatially advantageous manner and can be removed and fitted in a simple and uncomplicated manner, particularly in the case of repairs. Furthermore, transducers of this kind can be fitted to mass-produced speed governors for which electrical intervention was not originally intended. A massproduced speed governor can be equipped with a transducer of this kind, particularly when the speed governor is subsequently to be used as an isostatic governor.

A linear transducer of this type is particularly useful for measuring the centrifugally produced signal for comprehending the rotational speed in an isostatic governor in which the lever system of the governor is acted upon by way of a solenoid whose travel is also measured by means of a transducer, in order to vary the relative positions of the fuel quantity regulating member and the centrifugal speed signal generator in order to achieve a degree of proportionality of the overall governing as close as possible to 0%.

The invention is further described, by way of example, with reference to the drawing which is a greatly simplified diagram of a speed governor.

A centrifugal speed signal generator 2 is driven by the camshaft 1 of a fuel injection pump (not further illustrated) and, by way of governor lever 3 and an intermediate link 4, actuates the regulating rod 5, acting as a fuel quantity regulating member, of the injection pump. The centrifugal governor operates with fly-weights 6 which actuate an adjusting member 8 against the force of a return spring 7. The actuating member 8 is connected at least indirectly to the governor lever 3, and the armature 9 of a linear transducer 10 is secured to the actuating member 8. A ferromagnetic core 11 is disposed on the armature 9 and two induction coils 12 located axially adjacent to one another surround the core 11 in the transducer housing, so that displacement of the armature effects a corresponding voltage change in an electronic control device (not shown).The position of the armature 9 and thus the position of the adjusting member 8 are determinable thereby, each position corresponding to a specific rotational speed as a result of the centrifugal control. The sensor 10 is connected by way of electrical leads 13 to a plug 14 which is connected to a control device, particularly an electronic control device, by way of a corresponding cable (not illustrated).

The adjusting member 8 acts upon the governor lever 3 by way of a drag member 15, a drag spring 16 being arranged between the adjusting member 8 and the drag member 15. The use of a drag member is only dependent upon the design of the governor, although it is not required for the basic function of the governor which is described here. The governor lever 3 is pivoted at 1 6a and is articulated to the intermediate link 4 at 17. The pivot point 16a is variable by means of a linear electro-magnet 18 whose armature 19 can be pulled into a coil 20 against the force of a spring 21,the pivot point 16a being displaceable by way of a bell-crank lever 22 which is pivoted at 23.The extent of adjustment is measured by means of a linear transducer 24 whose armature 26 is displaceable by the bell-crank lever 22 against the force of a spring 25, whereby the armature 26 enters the coils 27. In principle, the construction of the transducer 24 corresponds to the construction of the transducer 10. Voltage is applied to the coil 27, and the measured value of the transducer 24 is transmitted, by way of electrical leads 28 which terminate at a plug 29 which is connected to the control device (not illustrated).

To ensure that the governor maintains the rotational speed constant in a desired manner, and has a very low degree of proportionality, the transducer 10, that is to say the adjusting member 8, must always assume the same position even when the load varies, since a specific rotational speed corresponds to each position. Thus, as soon as the preselected rotational speed varies for any reason, such as temperature or load, a corresponding output signal is formed in the electronic control device as a result of the ensuing signal change of the transducer 10 and, by means of this output signal, the solenoid 18 adjusts the pivot point 16 which results in corresponding displacement of the regulating rod 5, whereby the quantity of fuel injected is increased or decreased so as to achieve the desired rotational speed. The governor then operates on the integrall differential principle, stabilisation being achieved by way of the feedback which the transducer 24 renders possible for the position of the bell-crank lever.

It will be appreciated that a different type of adjusting mechanism can be used instead of a linear electromagnet 18. The same applies to the transducer 24 which has to be constructed in conformity with the adjusting mechanism.

Advantageously, the voltage from the transducers 10 and 24 can be used to stabilise the closed servo loop since, in particular, its differentiated signal is indicative of the speed of the adjusting movement of the parts which actuate the transducer. The acceleration of the parts can be measured by further differentiation.

Claims

1. A speed governor for a fuel injection pump having a centrifugal speed signal generator which is driven proportionally to the speed of the pump and which has fly-weight which actuate an adjusting member agaist at least one restoring force, a fuel quantity regulating member being displaceable by means of the adjusting member and a linear transducer for measuring the travel of the adjusting member.

2. A speed governor as claimed in claim 1 in which the linear transducer is an electrical transducer.

3. A speed governor as claimed in claim 2, in which the transducer is an inductive transducer having an armature which is displaceable relatively to at least one induction coil by means of the adjusting member.

4. A speed governor as claimed.in claim 3, in which a core of ferromagnetic material is arranged on the armature.

5. A speed governor as claimed in claim 3 or 4, in which the transducer has two coils arranged in tandem in the axial direction of the armature.

6. A speed governor as claimed in any preceding claim, in which the transducer is arranged in a servo-loop of the governor.

7. A speed governor as claimed in any of claims 2 to 5, which has an electronic control device adapted to form an electrical correction variable under evaluation of the value measured by the transducer and to intervene in the mechanically operating governor for the purpose of decreasing the degree of proportionality in the event of speed fluctuations at a pre-selected speed.

8. A speed governor as claimed in claim 7, in which a governor lever is arranged between the adjusting member of the centrifugal speed signal generator and the quantity regulating member, the pivot point of which governor lever is variable by way of an adjusting lever which is acted upon by an electrical adjusting motor controlled by the electro nic control device.

9. A speed governor as claimed in claim 8 in which a further transducer is provided for measuring the travel of the adjusting motor

10. A speed governor as claimed in claim 9 in which the further transducer is an electrical transducer and its output is fed back to the electronic control device.

11. A speed governor as claimed in any preceding claim, in which the measurement signals of the or each transducer are used to stabilise a closed servo-loop of the governor.

12. A speed governor as claimed in claim 11 when appendent to any of claims 7 to 10 in which the electronic control device is adapted to differentiate the measurement signals.

13. A speed governor constructed and adapted to operate substantially as herein described with reference to and as illustrated in the drawing.