DE102005007125B4 - Method and device for controlling an internal combustion engine - Google Patents

Abstract

Method for operating an internal combustion engine, in particular a self-igniting internal combustion engine, with at least one piston acted upon by a cylinder, in which an intake timing is adjusted, characterized in that the effective compression ratio in the cylinder is increased by an intake-closing control time (ES) at a Valve lift from zero to early in the direction of bottom dead center (UT) is adjusted.

Description

The The invention relates to a method and a device for controlling an internal combustion engine according to the preamble of the claim 1 and claim 9.

at non-operational lifting internal combustion engines and very low outside temperatures is at the start, especially in diesel-powered internal combustion engines, the gas temperature around top dead center is very important, because if the gas temperature is too low, the internal combustion engine does not start. Since the compression temperature is a function of compression is self-igniting Internal combustion engines selected a relatively high compression ratio. The effective compression ratio but is always smaller than the geometric compression ratio there for performance reasons the inlet-closing control time is clearly after the bottom dead center. In the coasting phases of the cools Combustion chamber, resulting in extension the so-called warm-up phase leads and higher Friction and higher Consumption as well as increased CO and HO emissions brings with it.

In the EP 1191211 A2 A method for operating a spark-ignited internal combustion engine is described, with which a throttle-poor part-load operation can be achieved in a simple manner by both the intake timing and the exhaust timing is shifted by a crank angle of about 30 ° to 100 ° to late. Among other things, it is mentioned that by using a fully variable valve train, it is possible to close the inlet valve much earlier, with the opening time unchanged, in order to reduce throttling losses.

In the DE 39 33 923 A1 describes a camshaft, with the centrifugal force dependent intake valves early at low speeds and late closing at high speeds.

task the present invention, it is in contrast, a method and a To provide an apparatus for operating an internal combustion engine, the improved operation, especially in a warm-up phase and at low speeds of the internal combustion engine allows.

The Task is according to the invention with the features of claim 1 and claim 9 solved.

The inventive method for operating an internal combustion engine is in addition to the generic Characteristics characterized in that an effective compression ratio in Cylinder raised is done by an intake-close control time on a valve lift from zero to early, towards bottom dead center is adjusted. By the approach at the bottom dead center, the effective compression ratio can be increased. There thereby increasing the compression temperature of a filling in the cylinder can lowered the geometric compression ratio and to a thermodynamic optimum led in diesel internal combustion engines at values between 14 to 15, resulting in a favorable consumption reduction follows. In deceleration phases, the braking energy is not on the brakes, but by the higher one Compression work inside the cylinder is converted into heat and the cooling of the cylinder or the combustion chamber prevented. This reduces fuel consumption by the resulting reduction in the friction of the cylinder bore as well like CO and HC emissions. The internal combustion engine is preferably self-igniting. Preferably will only be the intake-closing control time changed while the exhaust valve timing remains unchanged.

advantageous Further developments of the invention are specified in subclaims.

Prefers becomes the advance the inlet-closing control time placed at the bottom dead center, bringing the effective compression ratio maximum approximates to the geometric compression ratio.

In a cheap one Operating mode becomes shorter the warm-up phase when starting the internal combustion engine and below a first limit of a speed and / or load and / or Coolant temperature adjusts the intake-close control time to early.

Conveniently, is above a second limit of a speed and / or load and / or Coolant temperature the adjustment of the intake-close control time after morning is withdrawn. The two limits can to be different. The first and the second limit could also be the same be.

By a vehicle deceleration requested by driver's braking intervention becomes in a favorable Operational mode, the intake-close control time adjusted after early. A first part of a brake pedal travel is preferred at the beginning an operation the brake pedal, the adjustment of the intake-close control time after breakfast triggers.

at a cheap one Operation with two intake valves can both intake-close timing shifted to the bottom dead center or to the bottom dead center be switched.

at another cheap Operating mode, one of the intake valves can be completely switched off and the other will be closed at bottom dead center. This will the charge movement in the cylinder additionally increased, resulting in better combustion contributes.

The inventive device to carry out of the method is characterized in that an intake-close control time after breakfast is adjustable.

In a cheap one Embodiment is an additional cam contour to a cam contour switching in a camshaft intended. It's just an extra Cam contour necessary.

In a cheap one Embodiment may be on an intake side of a camshaft be provided fully variable valve train.

Further Embodiments and aspects of the invention will be independent of a summary in the claims without limitation of the Generality explained in more detail below with reference to a drawing. there the single figure shows a course of the valve lift with changed Intake closing control time.

1 to illustrate the invention, a valve lift of the exhaust valves (curve A) and the intake valves (curve E) over a crank angle ° KW of the crankshaft of an internal combustion engine. In the warm phase, the exhaust open control time is before the bottom dead center UT and the exhaust-close control time is after the top dead center OT (curve A). The intake-open control timing is before the top dead center OT and the intake-closing control time ES is after the bottom dead center UT (curve E).

According to the invention Intake closing control time IT after breakfast displaced (dashed curve) when an increase in the effective compression ratio required is, for. B. when a warm-up phase should be shortened. Preferably lies the inlet close time ES exactly at bottom dead center (UT) at valve lift zero.

LIST OF REFERENCE NUMBERS

IT

Intake closing control time

A

Exhaust valve timing

e

Intake valve timing

UT

lower dead

OT

upper dead

V

valve

° CA

crank angle

Claims (13)

Method for operating an internal combustion engine, in particular a self-igniting internal combustion engine, with at least one piston acted upon by a cylinder, in which an intake timing is adjusted, characterized in that the effective compression ratio in the cylinder is increased by an intake-closing control time (ES) at a Valve lift from zero to early in the direction of bottom dead center (UT) is adjusted. Method according to claim 1, characterized in that that the inlet-closing control time (ES) is placed on bottom dead center (UT). Method according to claim 1 or 2, characterized that when starting the internal combustion engine and below a first limit value of a speed and / or load and / or coolant temperature the inlet closing time (ES) after breakfast is adjusted. Method according to claim 3, characterized that above a second limit of a speed and / or load and / or coolant temperature the adjustment of the intake-close control time (ES) after early withdrawn becomes. Method according to claim 4, characterized in that that the first and second limits are different. Method according to claim 4, characterized in that that the first and second limits are the same. Method according to at least one of the preceding Claims, characterized in that requested by means of a driver-side brake intervention vehicle deceleration the inlet-closing control time (ES) after breakfast is adjusted. Method according to claim 7, characterized in that that a first part of a brake pedal travel at the beginning of an actuation of the Brake pedal triggers the adjustment of the intake close control time (ES) after early. Method according to at least one of the preceding Claims, characterized in that when operating with two inlet valves per cylinder, both intake-close timing (ES) to the bottom dead center (UT) shifted or to the bottom dead center be switched. Method according to at least one of the claims che 1 to 8, characterized in that when operating with two intake valves per cylinder one of the intake valves is turned off and the other is closed at or in the bottom dead center (UT). Apparatus for carrying out the method according to at least one of the preceding claims, characterized in that an inlet-closing control time (ES) is adjustable to early. Device according to claim 9, characterized in that that in a camshaft an additional cam contour to a Cam contour switching is provided. Device according to claim 9, characterized in that that on an inlet side of a camshaft a fully variable Valve gear is provided.

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