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DE-102018203699-B4 - Method for operating an internal combustion engine, control device for an internal combustion engine and internal combustion engine with such a control device

DE102018203699B4DE 102018203699 B4DE102018203699 B4DE 102018203699B4DE-102018203699-B4

Abstract

Method for operating an internal combustion engine (1) with at least one combustion chamber (3), wherein a quantity of fuel gas for combustion in the at least one combustion chamber (3) can be metered to the at least one combustion chamber (3) via a gas injection valve (5), wherein the gas injection valve (5) is controlled by means of a control signal for metering the quantity of fuel gas, wherein the control signal is determined depending on an operating time of the gas injection valve (5), and wherein the control signal is determined depending on an aging parameter, wherein the aging parameter is determined depending on the operating time of the gas injection valve (5), characterized in that an aging factor (k) is used as the aging parameter, which is calculated with a gas quantity target signal to determine the control signal, wherein an energization duration (t b ) for the gas injection valve (5) is used as the control signal, and wherein the energization duration (t b ) is determined according to the equation t b = m G m ˙ N ⋅ k + t o 2 − t c 2 is calculated using the amount of fuel gas m G supplied to the combustion chamber (3), the mass flow rate ṁ N through the fully opened gas injection valve (5) in its new state, the opening time t o and the closing time t c of the gas injection valve (5).

Inventors

  • Florian Joos
  • Alexander Bernhard
  • Andreas Mehr

Assignees

  • Rolls-Royce Solutions GmbH

Dates

Publication Date
20260513
Application Date
20180312

Claims (7)

  1. Method for operating an internal combustion engine (1) with at least one combustion chamber (3), wherein a quantity of fuel gas for combustion in the at least one combustion chamber (3) can be metered to the at least one combustion chamber (3) via a gas injection valve (5), wherein the gas injection valve (5) is controlled by means of a control signal for metering the quantity of fuel gas, wherein the control signal is determined depending on an operating time of the gas injection valve (5), and wherein the control signal is determined depending on an aging parameter, wherein the aging parameter is determined depending on the operating time of the gas injection valve (5), characterized in that an aging factor (k) is used as the aging parameter, which is calculated with a gas quantity preset signal to determine the control signal, wherein an energization duration (t b ) for the gas injection valve (5) is used as the control signal, and wherein the energization duration (t b ) is determined according to the equation t b = m G m ˙ N ⋅ k + t o 2 − t c 2 is calculated using the amount of fuel gas m G supplied to the combustion chamber (3), the mass flow rate ṁ N through the fully opened gas injection valve (5) in its new state, the opening time t o and the closing time t c of the gas injection valve (5).
  2. Procedure according to Claim 1 , characterized in that the control signal is additionally determined depending on a differential pressure falling across the gas injection valve (5).
  3. Method according to one of the preceding claims, characterized in that a plurality of gas injection valves (5) are used, wherein a separate control signal is determined for each gas injection valve (5) depending on the operating time of the respective gas injection valve (5).
  4. Method according to one of the preceding claims, characterized in that the aging parameter is reinitialized for the replaced gas injection valve (5) after a replacement of the gas injection valve (5).
  5. A method according to one of the preceding claims, characterized in that the aging parameter for the gas injection valve (5) is determined as a function of the operating time of the gas injection valve (5) by the following steps: - measuring a first valve characteristic for a new gas injection valve (5); - operating the gas injection valve (5) for at least one predetermined period of time; - measuring a further valve characteristic after each period of the at least one predetermined period of time; - comparing the first valve characteristic with the at least one further valve characteristic, and - deriving the aging parameter from the comparison.
  6. Control device (9) for an internal combustion engine (1), wherein the control device (9) is configured to carry out a procedure according to one of the Claims 1 until 5 .
  7. internal combustion engine (1), with a control device (9) according to Claim 6 .

Description

The invention relates to a method for operating an internal combustion engine, a control device for an internal combustion engine for carrying out such a method, and an internal combustion engine with such a control device. In a method for operating an internal combustion engine of the type discussed here, a quantity of fuel gas is metered to at least one combustion chamber of the engine via a gas injection valve for combustion in that combustion chamber. The gas injection valve is controlled by a control signal to meter the fuel gas quantity. Due to wear, such gas injection valves tend to have an increased flow cross-section with increasing operating time, and therefore to an increased gas injection quantity with a constant control signal, especially with a constant operating time. The control signals for different gas injection valves assigned to different combustion chambers of an internal combustion engine are typically generated by a control device designed to equalize the combustion conditions in the different combustion chambers, particularly by controlling the different gas injection valves differently. The control signals are subject to limits, particularly controller limits, which the control signals must not exceed or fall below. These limits, and thus the control margin, depend primarily on the gas injection valves used and their behavior over their operating lifetime. The controller limits are conventionally determined as a percentage of the average of all current durations for all gas injection valves. Due to the previously described aging effect, this average value shifts towards shorter current durations over the operating lifetime of the gas injection valves, and the controller limits also shift accordingly, proportionally. If an aged gas injection valve is replaced with a new one, the new valve will have a smaller flow cross-section, meaning it would actually require a longer current duration. Since the control limits are still calculated as a percentage of the average of all gas injection valve activation durations, it is quite possible that the actually required activation duration for the new gas injection valve is at or even beyond the upper control limit, meaning that the control unit cannot effectively control the new gas injection valve. Reliable, misfire-free operation of the internal combustion engine is then either impossible or only possible under difficult conditions. Alternatively, all gas injection valves must be replaced simultaneously, which is expensive and time-consuming. Out of US 2016 / 0 017 826 A1 A method according to the preamble of claim 1 emerges. DE 10 2006 023 468 B3 A method and a device for controlling an injection valve of an internal combustion engine are described. The invention is based on the objective of creating a method for operating an internal combustion engine, a control device for such an internal combustion engine which is configured to carry out such a method, and an internal combustion engine with such a control device, wherein the aforementioned disadvantages do not occur. The problem is solved by creating the subject matter of the independent claims. Advantageous embodiments result from the dependent claims. The problem is solved, in particular, by further developing a method of the described type such that the control signal is determined as a function of the operating time of the gas injection valve. Thus, the operating time of the gas injection valve is explicitly taken into account when determining the control signal, making it possible to generate a meaningful control signal for each gas injection valve of the internal combustion engine at any given operating time, regardless of the aging state of other gas injection valves. This makes it particularly possible, when replacing an aged gas injection valve with a new one, to explicitly consider its new condition when determining the control signal, so that this gas injection valve can be controlled meaningfully and correctly – regardless of the operating time of the other gas injection valves. Preferably, the control limits for the gas injection valve are determined individually, and not based on the average of all gas injection valves. In particular, the control limits are determined individually for each gas injection valve of the internal combustion engine, and preferably based on its operating time. It is also possible to determine the control limits as a percentage of the control signal, especially the duration of energization, for each individual gas injection valve. This allows the controller limits to be chosen more tightly around the actual current duration than is possible with conventional control methods. This is because extended controller limits for even Potential variations in the aging behavior of the different gas injection valves are taken into account. This increases the operational safety of the internal combustion engine. The process involves, in particular, the operatio