Methods of knock control

Abstract

A method for a knock control for an internal combustion engine with at least one cylinder, which is assigned to at least one intake valve, when knocking occurs in at least one cylinder by actuation of the intake valve associated with the cylinder detected as knocking, in such a way that the temperature of the charge of the cylinder detected as knocking is reduced, the knocking in the cylinder is reduced, on actuating the intake valve associated with the cylinder detected as knocking, a cylinder-specific and/or a global measure for power compensation of the internal combustion engine is performed.

Claims

1. A method, comprising: controlling one or more parameters of each combustion chamber of a plurality of combustion chambers of an internal combustion engine to reduce knock, wherein the one or more parameters are controlled differently for the plurality of combustion chambers depending on a level of input from one or more knock sensors, wherein the one or more parameters comprise at least closure times of a plurality of intake valves associated with the plurality of combustion chambers, wherein controlling comprises: identifying a knock condition associated with a combustion chamber of the plurality of combustion chambers based on the level of input from the one or more knock sensors; and adjusting a closure time of an intake valve of the plurality of intake valves associated with the combustion chambers to reduce the knock condition, wherein the closure time is adjusted to be earlier when the intake valve controls an intake of air without a cooled exhaust gas, or the closure time is adjusted to be later when the intake valve controls an intake of the air with the cooled exhaust gas.

2. The method of claim 1, wherein the closure time is adjusted to be earlier when the intake valve controls the intake of air without the cooled exhaust gas.

3. The method of claim 1, wherein the closure time is adjusted to be later when the intake valve controls the intake of the air with the cooled exhaust gas.

4. The method of claim 1, wherein the one or more parameters comprise opening durations of the intake valves associated with the plurality of combustion chambers.

5. The method of claim 4, wherein controlling comprises controlling a first intake valve to open for a shorter first opening duration for a first combustion chamber experiencing knock or greater knock relative to a second opening duration of a second intake valve for a second combustion chamber not experiencing knock or lesser knock based on the level of input from one or more knock sensors.

6. The method of claim 1, wherein the one or more parameters comprise power contributions of the plurality of combustion chambers.

7. The method of claim 6, wherein controlling comprises controlling a first power contribution to be lesser for a first combustion chamber experiencing knock or greater knock relative to a second power contribution for a second combustion chamber not experiencing knock or lesser knock.

8. The method of claim 1, comprising controlling a flow of a cooled fluid into at least one of the plurality of combustion chambers to reduce knock in response to the input from one or more knock sensors.

9. The method of claim 8, wherein the cooled fluid comprises a cooled inert fluid.

10. The method of claim 8, wherein the cooled fluid comprises the cooled exhaust gas.

11. A system, comprising: an engine controller configured to control one or more parameters of each combustion chamber of a plurality of combustion chambers of an internal combustion engine to reduce knock, wherein the one or more parameters are controlled differently for the plurality of combustion chambers depending on a level of input from one or more knock sensors, wherein the one or more parameters comprise at least closure times of a plurality of intake valves associated with the plurality of combustion chambers, wherein the engine controller is configured to: identify a knock condition associated with a combustion chamber of the plurality of combustion chambers based on the level of input from the one or more knock sensors; and adjust a closure time of an intake valve of the plurality of intake valves associated with the combustion chambers to reduce the knock condition, wherein the closure time is adjusted to be earlier when the intake valve controls an intake of air without a cooled exhaust gas, or the closure time is adjusted to be later when the intake valve controls an intake of the air with the cooled exhaust gas.

12. The system of claim 11, comprising the internal combustion engine having the engine controller.

13. The system of claim 12, comprising a variable valve train configured to provide variable control of the intake valves.

14. The system of claim 11, wherein the closure time is adjusted to be earlier when the intake valve controls the intake of air without the cooled exhaust gas.

15. The system of claim 11, wherein the one or more parameters comprise opening durations of the intake valves associated with the plurality of combustion chambers, wherein the engine controller is configured to control a first intake valve to open for a shorter first opening duration for a first combustion chamber experiencing knock or greater knock relative to a second opening duration of a second intake valve for a second combustion chamber not experiencing knock or lesser knock based on the level of input from one or more knock sensors.

16. The system of claim 11, wherein the one or more parameters comprise power contributions of the plurality of combustion chambers, wherein the engine controller is configured to control a first power contribution to be lesser for a first combustion chamber experiencing knock or greater knock relative to a second power contribution for a second combustion chamber not experiencing knock or lesser knock.

17. The system of claim 11, wherein the engine controller is configured to control a flow of a cooled fluid into at least one of the plurality of combustion chambers to reduce knock in response to the input from one or more knock sensors.

18. The system of claim 17, comprising an exhaust gas recirculation (EGR) system configured to recirculate an exhaust gas into an intake of the internal combustion engine, wherein the EGR system comprises a cooler configured to cool the exhaust gas to produce the cooled exhaust gas, wherein the cooled fluid comprises the cooled exhaust gas wherein the closure time is adjusted to be later as the intake valve controls the intake of the air with the cooled exhaust gas.

19. A system, comprising: an internal combustion engine having a plurality of combustion chambers and at least one intake valve associated with each combustion chamber of the plurality of combustion chambers; and an engine controller configured to control one or more parameters of each combustion chamber of the plurality of combustion chambers to reduce knock, wherein the one or more parameters are controlled differently for the plurality of combustion chambers depending on a level of input from one or more knock sensors, wherein the one or more parameters comprise at least closure times of a plurality of intake valves associated with the plurality of combustion chambers, wherein the engine controller is configured to: identify a knock condition associated with a combustion chamber of the plurality of combustion chambers based on the level of input from the one or more knock sensors; and adjust a closure time of an intake valve of the plurality of intake valves associated with the combustion chambers to reduce the knock condition, wherein the closure time is adjusted to be earlier when the intake valve controls an intake of air without a cooled exhaust gas, or the closure time is adjusted to be later when the intake valve controls an intake of the air with the cooled exhaust gas.

20. The system of claim 19, wherein the closure time is adjusted to be earlier when the intake valve controls the intake of air without the cooled exhaust gas, and the closure time is adjusted to be later when the intake valve controls the intake of the air with the cooled exhaust gas.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) In an embodiment explained in more detail with reference to the figures. The figures show the following:

(2) FIG. 1 A schematic representation of an internal combustion engine

(3) FIG. 2 A schematic representation of an internal combustion engine in a further exemplary embodiment,

(4) FIG. 3 Valve lift curves of an intake valve

DETAILED DESCRIPTION OF THE INVENTION

(5) FIG. 1 shows schematically an internal combustion engine 1 in a first exemplary embodiment, whereby only one cylinder 2 is shown. In practice, internal combustion engines often have multiple cylinders 2.

(6) Via an intake duct 10, a fuel-air mixture can enter a combustion chamber designed in the cylinder 2. The quantity and the time characteristics of the entry of the fuel-air mixture are determined by a variable actuatable intake valve 3. In other words, a variable valve train is implemented in the internal combustion engine 1. The actuation characteristics of the intake valve 3 can be changed by a control/regulating device 6.

(7) Via a knock sensor 4, characteristic signals for the knocking of the internal combustion engine can be sent to the control/regulating device 6.

(8) The knock sensor 4 can be designed as, for example, a structure-borne sound sensor.

(9) From the combustion chamber of the internal combustion engine 1, exhaust gas flows via an outlet valve 9 into an outlet duct 11.

(10) If knocking is detected by the knock sensor 4 in the cylinder 2, the control/regulating device 6 can control the intake valve 3 so that it closes earlier than during the last combustion cycle (the cycle in which knocking was detected). Because of the earlier closure of the intake valve 3, the charge participating in the compression decreases in the cylinder 2. The temperature of the charge of the cylinder detected as knocking 2 is thus reduced for the next combustion cycle compared to the preceding combustion cycle and the knocking in the cylinder concerned is reduced.

(11) FIG. 2 shows schematically an internal combustion engine 1 in a further exemplary embodiment whereby, in addition to the exemplary embodiment of FIG. 1, an EGR mechanism 5 is provided. For the variable valve train, the same as stated in 1 applies.

(12) The EGR mechanism 5 can branch off from the outlet duct 11 and pass back into the intake duct 10. The EGR mechanism 5 includes, in addition to the EGR line 12, a controllable valve 7 and a cooler 8. Through the cooler 8 designed as a heat exchanger, the temperature of the branched exhaust gas fed again into the intake duct 10 can be reduced. The quantity of the recirculated exhaust gas can be varied via the control/regulating device.

(13) If, in an internal combustion engine 1 of this form, i.e. with a cooled or coolable EGR mechanism 5, knocking is now detected by the knock sensor 4 in the cylinder 2, the control/regulating device 6 can control the intake valve 3 so that it closes earlier than during the last combustion cycle (the cycle in which knocking was detected). According to this variant, it is therefore provided that the temperature of the cylinder charge is reduced (and thus knocking is prevented) by supplying an increased quantity of cooled exhaust gas compared to the preceding combustion cycle into the cylinder 2 concerned. This results in a reduced temperature in the combustion in the compression stroke of the cylinder 2 concerned due to the increased quantity of inert ingredients in the cylinder charge compared to the preceding combustion cycle, whereby the cylinder 2 concerned is less prone to knocking.

(14) The signal connections of the control/regulating device 6 for the variably actuatable intake valve 3, the knock sensor 4 and the valve 7 of the EGR mechanism 5 are shown with dashed lines.

(15) FIG. 3 shows three valve lift curves a, b, c of the intake valves 3 according to the two exemplary embodiments discussed, as well as an output condition.

(16) Curve a represents the valve lift curve for the case in which, due to the earlier intake valve closure, the temperature of the cylinder charge is reduced and knocking is thus prevented.

(17) Curve b represents the valve lift curve during normal operation.

(18) Curve c represents the valve lift curve for the case in which, due to the later intake valve closure in connection with the cooled EGR mechanism 5, the temperature of the cylinder charge is reduced and knocking is thus prevented.

(19) It is seen that the valve opening time can remain unchanged due to the measures.

(20) This written description uses examples to disclose the invention, including the preferred embodiments, and also to enable any person skilled in the art to practice the invention, including making and using any devices or systems and performing any incorporated methods. The patentable scope of the invention is defined by the claims, and may include other examples that occur to those skilled in the art. Such other examples are intended to be within the scope of the claims if they have structural elements that do not differ from the literal language of the claims, or if they include equivalent structural elements with insubstantial differences from the literal languages of the claims.