GB1579101A

GB1579101A - Internal combustion engine

Info

Publication number: GB1579101A
Application number: GB1893078A
Authority: GB
Original assignee: Robert Bosch GmbH
Current assignee: Robert Bosch GmbH
Priority date: 1977-06-23
Filing date: 1978-05-11
Publication date: 1980-11-12
Also published as: JPS5410827A; DE2728205A1

Description

PATENT SPECIFICATION

( 11) 1 579 101 Application No 18930/78 ( 22) Filed 11 May 1978 ( 19) Convention Application No 2728205 ( 32) Filed 23 Jun1977 in X Fed Rep of Germany (DE)

Complete Specification Published 12 Nov 1980

INT CL ' F 02 D 3/00 I FON 3/20 B Ol D 53/36 \\ ' Index at Acceptance FIB 12 ( 16 12 G 2 A -12 U 3 U 12 G 3 C 12 ( 4 A 12 G 4 B 12 G 8 B 2 W B 102 B 120 B 122 B 204 B 212 B 228 B 236 B 312 BE Bl W X ( 54) AN INTERNAL COMBUSTION ENGINE ( 71) We, ROBERT BOSCH GMBH of 7000 Stuttgart 1, Postfach 50, Federal Republic of Germany, a limited liability company organised under the laws of the Federal Republic of Germany 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 present invention relates to an internal combustion engine.

In a known control device of a fuel supply system for an internal combustion engine, a catalyzer with a temperature sensor to measure the operating temperature is arranged in the exhaust duct The device at least partially interrupts the feed of the fuel or the fuel-air mixture at impermissibly high temperature of the catalyser in an overrun condition of the internal combustion engine This device, however, has the disadvantage that fuel is needlessly consumed up to the interruption of the fuel feed in the overrun condition and exhaust gases with a high proportion of toxic components are produced Additionally, the often desired engine braking effect in the overrun condition is impaired Another known control device of a fuel supply system for an internal combustion engine feeds, during the overrun condition, such an appreciable quantity of air to the internal combustion engine that the mixture feed is at least partially inhibited This is of disadvantage in that with the use of such a control device in an internal combustion engine having a catalyzer in the exhaust gas duct, the catalyzer during the overrun condition cools down below its lowest permissible operating temperature, after conclusion of the overrun condition and onset of the normal fuel supply, the catalyzer is initially too cold to reduce the injurious components of the exhaust gas.

According to the present invention there is provided an internal combustion engine provided with an induction pipe, an exhaust gas pipe, at least one catalyzer arranged in the exhaust gas pipe, and a fuel supply comprising control means arranged to interrupt, during an overrun condition of the engine, the supply of fuel to the engine in response to the temperature of the catalyzer exceeding the operating temperature thereof.

An embodiment of the present invention will now be more particularly described by way of example with reference to the accompanying drawing.

Referring now to the drawing, the control device of a fuel supply system for a mixturecompressing, externally ignited fourcylinder, four-stroke internal combustion engine 10 comprises four electromagnetically actuable injection valves 11, to which the fuel to be injected is fed from a distributor 12 by means of a respective pipe duct 13, an electrically driven fuel conveying pump 14, a pressure regulator 15, which regulates the fuel pressure in the fuel supply duct 16 to the injection valves 11 to a constant value, as well as an electrical regulating device, which is triggered twice on each cam shaft rotation by a signal transmitter 18 coupled with the cam shaft 17 of the internal combustion engine and which each time provides a rectangular electrical opening pulse S for the injection valves 11 The duration ti of the opening pulses determines the opening duration of the injection valves, and consequently the quantity of fuel which issues, dur( 21) ( 31) ( 33) ( 44) ( 51) po PI 4 ( 52) 1,579,101 ing the respective opening duration, out of the internal space of the injection valves 11 standing under a pratically constant fuel pressure of two bars The magnet windings 19 of the injection valves are each connected in series with a respective decoupling resistor and connected to a common amplifying and output stage of an electronic regulating equipment 21, which contains at least one output transistor which by its emittercollector path is arranged in series with the decoupling resistors 20 The magnet windings 19 are connected at one side to ground.

In mixture-compressing internal combustion engines operating with external ignition, the quantity of fuel, which can be completely burnt during the following operating cycle, is determined by the quantity of air inducted into a cylinder in a single induction stroke.

For a good utilization of the internal combustion engine no substantial excess air should be present after the operating cycle To attain the desired stoichiometric ratio between inducted air and fuel, an air measuring member is provided in the induction pipe 25 of the internal combustion engine downstream of a filter 26, but upstream of a throttle flap 28 displaceable by an accelerator pedal 27 The air measuring member basically comprises a baffle plate 30 and a variable resistor R, the adjustable tap 31 of which is coupled with the baffle plate The air measuring member co-operates with the electronic regulating equipment 21, which delivers the injection pulses ti at its output.

The electronic regulating device 21 contains two transistors, disposed at any time in mutually opposite operational state to each other and for this purpose cross-coupled with each other, as well as an energy storage, which may be a capacitor However, an inductor may be used in place of a capacitor.

The duration of the respective discharging process of the energy storage yields the opening duration ti of the injection valves For this purpose, the energy storage is each time charged in a defined manner before each discharge process.

To ensure that the discharge duration directly contains the necessary information about the quantity of air coming to the individual induction stroke, the charging-up takes place through a charging switch, which in the illustrated embodiment is shown in the form of a signal transmitter 18 The charging switch is actuated synchronously with the crank shaft rotations and has the effect that the energy storage is connected during the charging pulses LI, which extend over a determined constant rotational angle of the crank shaft, with a charging source which during the presence of the charging pulses each time delivers a charging current It is to be assumed in the present case that the signal transmitter, which in the practical realization may comprise a bistable multi-vibrator arranged to switch over to its opposite operational state each time by the ignition pulses, is closed over a crank shaft angle of 1800 and subsequently opened over the same rota 70 tional angle.

The operational state of the overrun condition of the internal combustion engine can be characterised by the signals of rotational speed of the internal combustion engine 75 above idling rotational speed and setting of the throttle flap in idling setting A throttle flap switch 33, which is closed in the idling setting of the throttle flap through the accelerator pedal 27 and thereby delivers a 80 corresponding signal to the electronic regulating equipment 21, serves for the determination of the idling setting of the throttle flap 28 The rotational speed of the internal combustion engine is provided to the elec 85 tronic regulating equipment 21 by the signal transmitter 18 When the signals characterising the overrun condition of the internal combustion engine are present in the electronic regulating equipment 21, then, on the 90 one hand, the injection signal ti at the output of the electronic regulating equipment 21 may be inhibited so that the injection valve 11 no longer receive opening signals, or as indicated in dashed lines, a blocking valve 34 95 may be arranged in the fuel supply duct 16 and driven by the output signal of the electronic regulating equipment 21 through a line 35 and an electrical setting motor 36 in such a manner that during the overrun condi 100 tion of the internal combustion engine it blocks the fuel supply duct 16 to the distributor 12 and opens a bypass 37, which leads back to the suction side of the fuel conveying pump 14 105 A catalyser 25, the temperature of which is measured by a temperature sensor 40 which supplies the measurement value to the electronic regulating equipment 21, is arranged in the exhaust gas pipe 38 of the internal 110 combustion engine for reduction of injurious components of the exhaust gas The interruption of the fuel feed in the overrun condition is now controlled in such a manner that an interruption of the fuel feed takes place only 115 when the catalyzer temperature lies above the operating temperature of the catalyzer or, respectively, the interruption of the fuel feed in the overrun condition is cancelled as soon as the catalyzer temperature drops 120 below the operating temperature of the catalyzer Thus, it is prevented that, on restoration of the fuel feed during the normal operation of the internal combustion engine after termination of the overrun condition, 125 no reduction of injurious exhaust gas components can at first take place through the catalyzer, since the temperature of the catalyzer lies below its operating temperature In order to prevent that the internal combustion 130 I 1,579,101 engine stops on disengagement from the driving vehicle during the overrun condition, a rotational speed switch is contained in the electronic regulating equipment 21 and cancels the fuel interruption at rotational speeds between 1000 and 1500 revolutions per minute in dependence on temperature, so that the internal combustion engine can run in idling.

When the fuel feed to the internal combustion engine is completely switched off during the overrun condition, then the internal combustion engine is fully dragged, i e it operates as compressor Thereby, the braking effect of the engine is greater than in normal engine operation with combustion in the overrun condition This braking effect may be further increased when care is taken that the internal combustion engine in the overrun condition is supplied exclusively with air, and with the greatest possible degree of filling (corresponding to full load operation), so that the compression force, which is taken up by the internal combustion engine and which is equal to the braking force, is as great as possible For this, it is expedient in the overrun condition to feed additional air into the induction pipe downstream of the throttle flap 28 As shown in the drawing, an air bypass 41 may serve for this purpose The air bypass 41 connects the induction pipe sections upstream of the air measuring member 30 and downstream of the throttle flap 28 and includes a blocking device 42 which is opened only during the overrun condition by a setting device 43 driven by a signal characterising the overrun condition and provided from the electronic regulating device 21 through line 35 The air bypass 41 may be so constructed that (as characterised by 44 in dashed lines) it connects the induction pipe section between air measuring member 30 and throttle flap 28 with the induction pipe section downstream of the throttle flap 28.

A device embodying the invention may without any restriction be used with either a fuel injection system or a carburettor for internal combustion engines A device embodying the invention, advantageously, may result in fuel saving and reduction of injurious components in the exhaust gas during the overrun condition of the internal combustion engine as long as the catalyser displays a temperature which lies above braking effect of the internal combustion engine during the overrun condition.

The feed of additional air to the internal combustion engine during the overrun condition at catalyzer temperatures above the catalyzer operating temperature is particularly advantageous to increase the engine braking effect.

Expediently, the control means of the fuel supply system for mixture-compressing, externally ignited internal combustion engines, serves for the interruption of the fuel feed to the internal combustion engine in an overrun condition The control means may comprise transmitters, which deliver 70 signals in dependence on the throttle flap setting, the rotational speed of the internal combustion engine and the temperature of a catalyzer arranged in the exhaust duct, and means for the evaluation of these signals and 75 for the interruption of the fuel feed to the internal combustion engine and for the addition of additional air in a pushing operation at catalyzer temperatures above the operating temperature of the catalyzer 80

Claims

WHAT WE CLAIM IS:-

1 An internal combustion engine provided with an induction pipe, an exhaust gas pipe at least one catalyser arranged in the exhaust gas pipe, and a fuel supply system 85 comprising control means arranged to interrupt, during an overrun condition of the engine, the supply of fuel to the engine in response to the temperature of the catalyzer exceeding the operating temperature 90 thereof.

2 An engine as claimed in claim 1, wherein the control means comprises means actuable to open an air channel connected to the induction pipe in such a manner as to 95 bypass the throttle member, the control means being arranged to actuate the actuable means during the overrun condition of the engine and when the temperature of the catalyzer exceeds the operating temperature 100 thereof.

3 An engine as claimed in claim 2, wherein the induction pipe sections upstream and downstream of a throttle member are connectible by the air channel 105 during the overrun condition of the engine and when the temperature of the catalyzer exceeds the operating temperature thereof.

4 An engine as claimed in claim 2, wherein the induction pipe sections 110 upstream of a fuel supply input and downstream of the throttle member are connectible by means of the air channel during the overrun condition of the engine and when the temperature of the catalyzer exceeds the 115 operating temperature thereof.

An engine as claimed in any one of claims 2 to 4, comprising air measuring means arranged in the induction pipe, the induction pipe section upstream of the air 120 measuring means and the induction pipe section downstream of the throttle member being connectible by means of the air channel during the overrun condition of the engine and when the temperature of the 125 catalyzer exceeds the operating temperature thereof.

6 An engine as claimed in any one of the preceding claims, wherein the fuel supply system comprises a fuel supply duct including 130 4 1,579,101 4 a fuel conveying pump, the control means comprising valve means arranged in the fuel supply duct downstream of the fuel conveying pump to interrupt the flow of fuel to the engine and to convey pumped fuel back to the suction side of the fuel conveying pump through a fuel bypass channel during the overrun condition of the engine and when the temperature of the catalyzer exceeds the operating temperature thereof.

7 An internal combustion engine substantially as hereinbefore described with reference to and as shown in the accompanying drawing.

8 An engine as claimed in any one of the preceding claims and arranged to operate as a mixture-compressing, externally ignited internal combustion engine.

DR WALTHER WOLFF & CO, 6 Buckingham Gate, London SW 1 E 6 JP Chartered Patent Agents, Agents for the Applicants Printed for Her Majesty's Stationery Office, by Croydon Printing Company Limited, Croydon, Surrey 1980.

Published by The Patent Office, 25 Southampton Buildings, London, WC 2 A IAY, from which copies may be obtained.