EP0350500A1

EP0350500A1 - Diesel internal combustion engine, in particular for vehicles.

Info

Publication number: EP0350500A1
Application number: EP88909983A
Authority: EP
Inventors: Gerhard Stumpp
Original assignee: Robert Bosch GmbH
Current assignee: Robert Bosch GmbH
Priority date: 1987-12-02
Filing date: 1988-11-25
Publication date: 1990-01-17
Anticipated expiration: 2008-11-25
Also published as: DE3740803A1; EP0350500B1; DE3865015D1; DE3740803C2; WO1989005395A1; US5036808A

Abstract

Un moteur diésel comprend un tuyau d'aspiration d'air (12) dans lequel est agencée une soupape d'étranglement (16). Afin d'éviter des états de fonctionnement préjudiciables au moteur, par exemple un dépassement incontrôlé du régime maximal admissible, suite à des dérangements, la soupape d'étranglement (16) est pourvue d'un mécanisme d'entraînement (17) qui la maintient ouverte en l'absence de dérangements et qui la met en position de fermeture en cas de dérangements. La position de fermeture de la soupape d'étranglement (16) est réglée de sorte que la section transversale d'écoulement d'air qui en résulte soit réduite à un point tel que le moteur puisse continuer à tourner même en vitesse de marche à vide d'une part et d'autre part qu'il ne dépasse pas une vitesse de rotation prédéterminée lorsqu'une quantité arbitraire de carburant lui est fournie.A diesel engine comprises an air suction pipe (12) in which is arranged a throttle valve (16). In order to avoid operating conditions which are detrimental to the engine, for example an uncontrolled exceeding of the maximum permissible speed, following faults, the throttle valve (16) is provided with a drive mechanism (17) which maintains it. open in the absence of faults and which places it in the closed position in the event of faults. The closed position of the throttle valve (16) is adjusted so that the resulting air flow cross section is reduced to such an extent that the engine can continue to run even at idle speed. on the one hand and on the other hand that it does not exceed a predetermined rotational speed when an arbitrary quantity of fuel is supplied to it.

Description

Diesel internal combustion engine, in particular for vehicles

State of the art

The invention relates to a diesel internal combustion engine, in particular for vehicles, of the type defined in the preamble of claim 1.

If in such a diesel internal combustion engine for vehicles more combustible fuel-air mixture is supplied to the combustion cylinders due to malfunctions than is specified by the driver by actuating the accelerator pedal, a dangerous operating state can arise. Exceeding the permissible maximum speed can damage the internal combustion engine or lead to accidents due to not being able to "accelerate" ("automatic throttle").

It is already known for diesel engines with fuel injection pumps, in such cases by means of a Emergency stop device the power supply to the

Turn off the fuel injection pump so that the engine goes out after the pump interior of the fuel injection pump is emptied (DE-OS 30 04 335). In the case of fuel injection pumps with a large pump interior, the reaction time, i.e. the time from the occurrence of the fault until the engine stops, relatively long. The emptying of the pump interior can be accelerated by additional measures and thus the reaction time of the emergency stop device can be shortened.

Advantages of the invention

The diesel internal combustion engine according to the invention with the characterizing features of claim 1 has the advantage that the internal combustion engine is not switched off but only limited in speed when the fuel supply is too high. The necessary for this

Safety device is structurally very simple and can be implemented with simple means. In addition, their function can be checked during engine operation, namely at idle, continuously or from time to time, so that a higher level of safety is provided. The safety device according to the invention is characterized by an extremely short reaction time.

Advantageous further developments and improvements of the diesel internal combustion engine specified in claim 1 are possible through the measures listed in the further claims.

In accordance with an advantageous embodiment of the invention, the valve drive is constructed from a drive spring acting in the closing direction of the throttle valve and an electric, pneumatic or hydraulic motor acting in the opening direction of the throttle valve, a safe operating state is always achieved without auxiliary energy Internal combustion engine reached. A defect in the safety device automatically leads to the safe operating state of the internal combustion engine.

By the monitoring unit provided according to a further embodiment of the invention, which in the case of its

Switching on a closing signal for the damper actuator, i.e. in the formation of the flap drive as indicated above, a shutdown signal for the engine, then outputs when the engine is warm, absolute idle conditions, such as idle speed

Internal combustion engine, idle position of the accelerator pedal, supplied to the combustion cylinders

Idle fuel injection quantity, prevail, the function of the safety device can be checked without impairing the driving operation and unnoticed by the driver. If the throttle valve does not assume its predetermined closed position during idle conditions and the output of the closing signal for the throttle valve drive, a warning lamp is switched on, which signals the failure of the safety device to the driver and causes him to visit a workshop. It is sufficient if the functional check of the safety device is carried out by the monitoring unit once each time the internal combustion engine is restarted when the internal combustion engine is at operating temperature. It is also possible to carry out an ongoing check in every idle phase of the internal combustion engine.

The sensor required for the monitoring device to detect the closed position of the throttle valve can be designed in various ways. As a pressure sensor, it will recognize the closed position of the throttle valve when the pressure downstream of the throttle valve drops to a preset value. As an airflow meter, it will signal the closed position of the throttle valve when the amount of air measured downstream of the throttle valve per unit of time drops below a limit value. As a lambda probe in the exhaust gas flow, it can recognize the closed position of the throttle when the λ value drops below a limit value. When the sensor is designed as an exhaust gas temperature sensor, it can recognize the closed position of the throttle by the fact that the exhaust gas temperature exceeds a predetermined limit value. Finally, the sensor can also be designed as a simple electrical switch which is actuated by the throttle valve in its closed position.

According to a preferred embodiment of the invention, the throttle valve is arranged as close as possible to the intake valves of the combustion cylinders, namely downstream of a crankcase ventilation, so that the air volume between the throttle valve and intake valves is as small as possible and very short reaction times are thus achieved.

In the case of diesel engines with turbochargers, the throttle valve must be arranged downstream of the air compressor of the turbocharger.

drawing

The invention is based on an embodiment shown in the drawing in the following

Description explained in more detail. The drawing shows a schematic representation of a diesel engine with a safety device.

Description of the embodiment

In the diesel internal combustion engine shown schematically in FIG. 1, 10 denotes the cylinder block in which the combustion cylinders are combined. Fuel is preferably supplied to the combustion cylinders by means of a fuel injection pump, which is symbolized by an arrow 11. The one required for the combustion of the fuel Combustion air enters the combustion cylinders via the intake valves, not shown. The air is supplied to the intake valves through an air intake pipe 12. The combustion gases expelled from the combustion cylinders are blown into the environment via an exhaust gas collection pipe. In diesel internal combustion engines with turbochargers, the drive turbine 14 of the turbocharger is arranged in the exhaust gas collection pipe 13, while the air compressor 15 rigidly coupled to the drive turbine 14 is seated in the air intake pipe 12.

In the air intake pipe 12, downstream of the air compressor 15, the intake valves of the combustion cylinders immediately upstream, a throttle valve 16 is pivotally held, which can be converted from a closed position indicated by a broken line to an open position shown in a broken line and vice versa. In the open position, the throttle valve 16 releases the full air passage cross section of the air intake pipe 12, which in the closed position is reduced to a cross section in which the combustion air passing through the remaining air gap is throttled to such an extent that the internal combustion engine on the one hand is still running reliably at idling speed and on the other hand at Any amount of fuel supplied to the combustion cylinder does not exceed a predetermined speed.

The flap drive 17 consists of a drive spring 18 acting in the closing direction of the throttle valve 16 and of a pneumatic motor 19 acting in the opening direction of the throttle valve 16. Such a motor 19 consists in a known manner, for example of a diaphragm drive with a pressurizable diaphragm or of a working cylinder 20 with a working piston 21 axially guided therein, which are connected to the throttle valve 16. Working cylinder 20 and working piston 21 delimit a working chamber 22 which is connected to a compressed air reservoir 24 via a compressed air line 23. In the compressed air line 23, a compressed air control valve, preferably a 3/2-way solenoid valve 25, is arranged for venting and venting the work chambers 22. The solenoid valve 25 is controlled by a control device, which is combined to form a control unit 26 together with a monitoring unit which is still detailed.

Throttle valve 16, flap drive 17 and control device 0. Of control unit 26 form a safety device which ensures that the combustion cylinders are supplied with a combustible fuel-air mixture which is not more than that specified by the driver by actuating the accelerator pedal. This prevents the occurrence of a 5th dangerous state for the internal combustion engine, such as exceeding the maximum speed. In detail, the safety device works as follows:

When the internal combustion engine is operating properly, the throttle valve 16 assumes its θ open position, as shown in the drawing, since the energized solenoid valve 25 connects the working chamber 22 of the pneumatic motor 19 to the compressed air reservoir 24. If a malfunction occurs, for example clamping the control rod of the fuel injection pump, which leads to an undesired and uncontrolled increase in engine speed 5, the malfunction is recognized and a malfunction signal is sent to the control device in control unit 26. Such a fault signal can be determined, for example, from a permanent control deviation between the calculated target injection quantity and the actual injection quantity, as described in DE-OS 33 04 335. When the fault signal occurs, the solenoid valve 25 is switched currentless via the control unit 26. This switches in Working position in which the working chamber 22 of the pneumatic motor 19 is vented. The tensioned closing spring 18 of the flap drive 17 moves the working piston 21 downward in the drawing, as a result of which the throttle flap 16 is transferred into its closed position shown in dashed lines in the drawing. In this closed position, the combustion air entering the combustion cylinder via the inlet valves is throttled to such an extent that a predetermined speed is not exceeded when any quantity of fuel is supplied to the combustion cylinder. At the same time, however, so much combustion air is supplied that the internal combustion engine still runs safely and smoothly in its idle number. As soon as the malfunction has been eliminated and the malfunction signal is no longer present, the solenoid valve 25 returns after energizing the

Excitation winding back into its basic position and connects the working chamber 22 to the compressed air reservoir 24. The compressed air flowing into the working chamber 22 moves the working piston 21 upwards in the drawing while the closing spring 18 is tensioned, and the working piston 21 pivots the throttle valve 16 into its open position.

A monitoring unit is integrated in the control unit 26 to check the function of the safety device. This monitoring unit gives a closing signal to the flap drive 17 when the accelerator pedal is idling when the internal combustion engine is warm and at idle speed and the amount of fuel supplied to the combustion cylinders corresponds to the idle fuel injection amount. The

The closed position of the throttle valve 16 is detected by a sensor 27 and fed to the control unit 26. If there is no sensor signal signaling the closed position of the throttle valve 16 when a closing signal is output, the monitoring unit switches on a warning light 28 which informs the driver of the malfunction of the safety device signals. The activation of the monitoring unit is only operated once after each restart of the internal combustion engine.

To carry out this monitoring function, three signal lines 1, 2 and 3 are connected to the control unit 26; the position of the accelerator pedal is displayed to the control unit 26 via the signal line 1. The signal line 2 is connected to a speed sensor, which delivers a signal proportional to the speed of the internal combustion engine. The signal line 3 is connected to a temperature sensor, which measures the temperature of the cylinder block 10 and outputs it as an electrical signal. The sensor 27 which senses the closed position of the throttle valve 16 is designed in the exemplary embodiment shown in the drawing as a pressure sensor 28 which measures the boost pressure in the air intake pipe 12 downstream of the throttle valve 16. An electrical signal proportional to the pressure is fed to the control device 26 and compared here with a preset value. If the value falls below the preset value, the safety device is recognized as functional. In the other case, the warning light 28 is switched on.

The sensor 27 can also be designed as an air flow meter, which measures the amount of air that passes through the air flow cross section released by the throttle valve 16. As a further possibility, a lambda probe arranged in the exhaust gas collection tube 13 or an exhaust gas temperature probe can be used; If the A value falls below or exceeds the exhaust gas temperature, this is an indication of the closed position of the throttle valve 16. In the simplest embodiment, the sensor 27 can be designed as an electrical switch that is actuated by the throttle valve 16 in its closed position and with Close supplies a signal to the control unit 26. The invention is not limited to the exemplary embodiment described. Thus, the motor component of the flap drive 17 can be designed not only pneumatically but also hydraulically or electrically.

Claims

Expectations

1. Diesel internal combustion engine with an air intake pipe for supplying combustion air to the combustion cylinders and with a throttle valve which is pivotally arranged in the air intake pipe and which determines the air flow cross section of the air intake pipe, characterized by a flap drive (17) acting on the throttle valve (16) for its pivoting and a control device controlling the same (26), which in the undisturbed operation of the internal combustion engine triggers an opening of the throttle valve (16) which releases the full air flow cross section and, in the event of disturbed operation, closes the throttle valve (16) to a reduced air flow cross section, in which the intake combustion air is throttled to such an extent that the internal combustion engine on the one hand, it is still running safely at idling speed and, on the other hand, it does not exceed a predetermined speed when any quantity of fuel is fed into the combustion cylinder (10).

2. Internal combustion engine according to claim 1, characterized in that the flap drive (17) a drive spring (18) acting in the closing direction of the throttle valve (16) and a motor (19) acting in the opening direction of the throttle valve (16), e.g. electrical, pneumatic or hydraulic type.

3. Internal combustion engine according to claim 1 or 2, characterized by an effective idle monitoring unit (26) for checking the function of throttle valve (16) and valve actuator (17).

4. Internal combustion engine according to claim 3, characterized in that the monitoring unit (26) is activated only once after each start.

5. Internal combustion engine according to claim 3 or 4, characterized in that the monitoring unit (26) outputs a closing signal to the flap drive (17) when the accelerator pedal is in the idle position when the internal combustion engine is warm and at idle speed and the fuel quantity supplied to the combustion cylinders (10) corresponds to the idle fuel quantity, and that a sensor (27) sensing at least the closed position of the throttle valve (16) is provided.

6. Internal combustion engine according to claim 5, characterized gekenn¬ characterized in that the output signal of the sensor (27) of the monitoring unit (26) is supplied, which outputs a warning signal when the output signal is not representative of the closed position of the throttle valve (16) is.

7. Internal combustion engine according to one of claims 3-6, characterized in that the monitoring unit and the control device are combined to form a control unit (26).

8. Internal combustion engine according to one of claims 4-7, characterized in that the sensor (27) is designed as a pressure sensor (28) which measures the pressure in the air intake pipe (12) downstream of the throttle valve (16).

9. Internal combustion engine according to one of claims 4-7, characterized in that the sensor (27) as.

Air flow meter is formed, which measures the amount of air passing through the air flow cross section released by the throttle valve (16).

10. Internal combustion engine according to one of claims 4-7, characterized in that the sensor (27) is designed as a lambda probe arranged in the exhaust (13) of the internal combustion engine.

11. Internal combustion engine according to any one of claims 4-7, characterized in that the sensor (27) is designed as an exhaust gas temperature sensor.

12. Internal combustion engine according to one of claims 4-7, characterized in that the sensor (27) is designed as an electrical switch which is actuated by the throttle valve (16) in its closed position.

13. Internal combustion engine according to any one of claims 1-12, characterized in that the throttle valve (16) in the air intake pipe (12) is arranged such that the pipe volume is as small as possible downstream to the inlet valves of the combustion cylinder (10).

14. Internal combustion engine in one of claims 1-13, with an air compressor and a drive turbine having turbocharger, characterized in that the throttle valve (16) is arranged downstream of the air corapressor (15).