GB2550169A - Method for operating engine - Google Patents

Abstract

A method for operating an engine 12, eg a four-stroke gaseous-fuelled or bi-fuel engine, in the event of failure of at least one cylinder temperature sensor 30, includes (a) associating a knock sensor 32 with at least one cylinder, (b) receiving, by an electronic controller (ECU) 14, an output signal S from the knock sensor 32, (c) detecting if the output signal S is above a first predetermined knock threshold V1, (e) determining the occurrence of a combustion event within the cylinder based on the detection of the output signal, and (f) terminating, eg by generating an action signal X, the operation of the engine if the output signal S is below the first predetermined knock threshold V1. The ECU may also determine that there is knocking if the signal S is above a second, greater, threshold V2.

Description

METHOD FOR OPERATING ENGINE

Technical Field [0001] The present disclosure generally relates to an engine, and more particularly to a method for operating the engine.

Background [0002] Engines, such as gaseous fuel operated engines, generally include a temperature sensor to determine combustion temperature within a cylinder of the engine. The measured temperature is used as an indicator of correct functionality of the engine and is also used as an input to an engine control system. In case of a failure of the temperature sensor, it is difficult to detect combustion parameters inside the cylinder. For example, the cylinder may be cranked without combustion, in case a spark plug associated with the cylinder is broken. As a consequence, the engine is stopped if one or more temperature sensors fail.

[0003] US Patent Number 5,934,256 hereinafter referred to as the ’256 patent, describes a method for detecting irregular combustion processes in a multi cylinder diesel internal combustion engine. The method includes detecting incorrect injections and non-injections by recording combustion noise in individual cylinders through the use of one or more structure-borne noise sensors. Subsequently, a check is performed as to whether or not sensor signals exceed threshold values individual to each cylinder within or outside fixed measurement windows. However, the ’256 patent does not describe a method to monitor combustion within the engine cylinder in an event of failure of the temperature sensor.

Summary of the Disclosure [0004] In one aspect of the present disclosure, a method of operating an engine in an event of failure of at least one temperature sensor of the engine is described. In the engine, the temperature sensor is adapted to determine a combustion temperature within at least one cylinder of the engine. The method includes associating a knock sensor with the at least one cylinder. The knock sensor is adapted to measure vibrations in the at least one cylinder. The method also includes receiving, by an electronic controller, an output signal from the knock sensor. The method further includes detecting if the output signal is above a first predetermined knock threshold. The method includes determining occurrence of a combustion event within the at least one cylinder, based on the detection of the output signal. The method also includes terminating the operation of the engine, if the output signal is below the first predetermined knock threshold.

[0005] Other features and aspects of this disclosure will be apparent from the following description and the accompanying drawings.

Brief Description of the Drawings [0006] FIG. 1 is a perspective view of an exemplary engine system having an engine, according to an embodiment of the present disclosure; [0007] FIG. 2 is a sectional view of the engine of FIG. 1 having a cylinder; [0008] FIG. 3 is a block diagram of the engine system of FIG. 1; [0009] FIG. 4 is a flowchart for a process of operating the engine of FIG. 1; and [0010] FIG. 5 is a flowchart for a method of operating the engine of FIG. 1. Detailed Description [0011] Reference will now be made in detail to specific aspects or features, examples of which are illustrated in the accompanying drawings. Wherever possible, corresponding or similar reference numbers will be used throughout the drawings to refer to the same or corresponding parts.

[0012] FIG. 1 illustrates an exemplary engine system 10 having an engine 12. For the purposes of this disclosure, the engine 12 is depicted and described as a four-stroke gaseous-fueled engine. One skilled in the art will recognize, however, that the engine 12 may alternatively include a two-stroke engine or a four-stroke engine that uses other types of fuel, if desired, without limiting the scope of the present disclosure. The engine 12 may include an engine block 16. Further, the engine 12 includes a number of cylinders 18; one such cylinder 18 is shown in FIG. 2. It may be contemplated that the cylinders 18 may be disposed in an “in-line” configuration, in a “V” configuration, in an opposing-piston configuration, or in any other suitable configuration. In the illustration of FIG. 1, the engine 12 is shown as a V-12 engine having twelve cylinders (only six shown in FIG. 1) arranged in a V-configuration.

[0013] For explanatory purposes, a sectional view of the engine 12 illustrating a single cylinder 18 is shown in FIG. 2. The cylinder 18 includes a piston 20 that is slidably disposed within the cylinder 18 to reciprocate between a top-dead-center (TDC) position and a bottom-dead-center (BDC) position. Further, a cylinder head 22 may be associated with the cylinder 18. The cylinder 18, the piston 20, and the cylinder head 22 may together define a combustion chamber 24. The cylinder 18 also includes a spark plug 25 for ignition of fuel inside the combustion chamber 24. Further, the cylinder 18 includes an inlet valve 27 and an outlet valve 29 for supply of the fuel inside the combustion chamber 24 and release of the exhaust gases, respectively.

[0014] The engine 12 may also include a crankshaft 26 that is rotatably disposed within the engine block 16. A connecting rod 28 may connect each piston 20 to the crankshaft 26 so that a sliding motion of the piston 20 between the TDC and BDC positions within the cylinder 18 results in a rotation of the crankshaft 26. Similarly, a rotation of the crankshaft 26 may result in a sliding motion of the piston 20 between the TDC and the BDC positions. In a four-stroke engine, the piston 20 may reciprocate between the TDC and the BDC positions through an intake stroke, a compression stroke, a combustion or power stroke, and an exhaust stroke. In a two-stroke engine, a complete cycle may include a compression/exhaust stroke (BDC to TDC) and a power/exhaust/intake stroke (TDC to BDC).

[0015] Further, the engine system 10 includes an electronic controller 14 (shown in FIG. 3). It may be contemplated that the electronic controller 14, as defined herein, may be a module being executed by an Electronic Control Unit (ECU), or alternatively the electronic controller 14 may be in communication with the ECU of the engine 12 to receive information about the operating conditions of the engine 12. The electronic controller 14 may include a processor (not shown) for carrying out operations for controlling each part of the engine 12, a memory (not shown) for storing programs and various data to control each part of the engine 12. The memory may further store temporary data received from each part of the engine 12 as well as control signals to be sent out to each part of the engine 12. The electronic controller 14 may also include an input circuit (not shown) for receiving data sent from each part of the engine 12, and an output circuit (not shown) for sending control signals to each part of the engine 12.

[0016] As shown in FIG. 2, the cylinder 18 of the engine 12 is provided with a temperature sensor 30. The temperature sensor 30 may be any type of temperature measuring device that may be used for measuring temperature inside the combustion chamber 24. In one example, the temperature sensor 30 may be a thermocouple which uses two wire legs made from different materials which produces a temperature-dependent voltage as a result of the thermoelectric effect, and this voltage may be interpreted to measure combustion temperature. In other examples, the temperature sensor 30 may include a resistance thermometer or the like, without limiting the scope of the present disclosure. Typically, the temperature sensor 30 may be screwed into the cylinder head 22 and protrudes through an opening (not shown) into the combustion chamber 24. This way the temperature sensor 30 may be able to directly measure a combustion temperature inside the combustion chamber 24 of the cylinder 18.

[0017] The temperature sensor 30 may generate a temperature signal ‘T’ indicative of the determined combustion temperature. As illustrated in FIG. 3, the temperature sensor 30 is in signal communication with the electronic controller 14. The electronic controller 14 receives the temperature signal ‘Τ’ from the temperature sensor 30. Further, the electronic controller 14 detects occurrence of a combustion event within the cylinder 18 based on the receipt of the temperature signal ‘Τ’. Generally, the electronic controller 14 validates the occurrence of the combustion event when the temperature signal ‘Τ’ exceeds a predefined temperature threshold. Such techniques for inferring the occurrence of the combustion event using the temperature signal are well known in the art and have not been described in detail herein for the brevity of the disclosure.

[0018] Referring to FIG. 1, the engine system 10 also includes a knock sensor 32. The knock sensor 32 may be mounted at a suitable location on the engine block 16 to measure vibrations associated with the cylinder 18. In some examples, the engine system 10 may include multiple knock sensors 32. For example, each cylinder 18 of the engine 12 may include one associated knock sensor 32. It may be contemplated that the location of the knock sensor 32, as illustrated in FIGS. 1-2, is exemplary only and may vary based on space constraints and dimensions of the engine block 16, among various other factors. In some examples, the knock sensor 32 may be an acceleration sensor working on the principle of piezo-electric effect to measure acoustic vibrations associated with each cylinder 18 of the engine 12. The knock sensor 32 may achieve this by measuring cavity resonance frequency of the combustion chamber 24. The knock sensor 32 may be of a kind commercially available and tuned to sense vibrations in a range about a cavity resonance frequency of the corresponding cylinder 18, without limiting the scope of the present disclosure.

[0019] Further, the knock sensor 32 generates an output signal ‘S’ indicative of the magnitude of the vibrations in the corresponding cylinder 18 of the engine 12. Referring to FIG. 3, the knock sensor 32 is in signal communication with the electronic controller 14, such that the output signal ‘S’, generated by the knock sensor 32, is received by the electronic controller 14. The engine system 10 may include suitable wired or wireless means for transmission of the output signal ‘S’ from the knock sensor 32 to the electronic controller 14. In some examples, the knock sensor 32 transmits the output signal ‘S’ to the electronic controller 14 via a channel (not shown) which includes one or more of an amplifier, a bandpass filter, and a demodulator of known designs and functions to those skilled in the art, and accordingly the detailed circuitry of these components is not discussed herein.

[0020] In one embodiment of the present disclosure, the electronic controller 14 detects the occurrence of the combustion event within the cylinder 18 based on the output signal ‘S’. The combustion event in the combustion chamber 24 may induce some vibrations in the corresponding cylinder 18. More vigorous the combustion event, higher the resultant amplitude of the vibrations in the cylinder 18, and correspondingly higher the magnitude of the output signal ‘S’ indicative of the vibrations in the cylinder 18. Thus, the magnitude of the output signal ‘S’ may be used as a reference for detecting the combustion event in the cylinder 18.

[0021] The electronic controller 14 detects the occurrence of the combustion event within the cylinder 18 by comparing the magnitude of the output signal ‘S’ with a first predetermined knock threshold ‘VI’. According to one example, the value of the first predetermined knock threshold ‘VI’ may be set corresponding to the vibrations in the cylinder 18 just when the combustion event begins. The electronic controller 14 detects if the output signal ‘S’ is above the first predetermined knock threshold ‘VI’. Therefore, the output signal ‘S’ above the first predetermined knock threshold ‘VI’ is indicative of the occurrence of the combustion event in the cylinder 18. Conversely, the output signal ‘S’ below the first predetermined knock threshold ‘VI’ is indicative of absence of the combustion event in the corresponding cylinder 18.

[0022] In some examples, the engine system 10 may include a database 34 for storing and retrieving the first predetermined knock threshold ‘VI’. In particular, the database 34 may store various possible values of the first predetermined knock threshold ‘VI’ based on the different operating conditions of the engine 12. For this purpose, the database 34 may be in communication with the electronic controller 14. The electronic controller 14 may send instructions to the database 34 based on the operating conditions of the engine 12 in order to retrieve the first predetermined knock threshold ‘VI’ corresponding to the given operating conditions of the engine 12.

[0023] The electronic controller 14 compares the voltage of the output signal ‘S’ to the magnitude of the respective reference voltages corresponding to the first predetermined knock threshold ‘VI’. In one example, the electronic controller 14 determines if the output signal ‘S’ is below the first predetermined knock threshold ‘VI’. Further, the electronic controller 14 generates an action signal ‘X’ in response to the magnitude of the output signal ‘S’ being below the first predetermined knock threshold ‘VI’. In some examples, the electronic controller 14 may output the action signal ‘X’ in response to a portion of the output signal ‘S’ being below the first predetermined knock threshold ‘VI’. In one example, the generation of the action signal ‘X’ leads to a termination of the operation of the engine 12.

[0024] Further, the electronic controller 14 also determines if the output signal ‘S’ is above a second predetermined knock threshold ‘V2’. If the output signal ‘S’ is above the second predetermined knock threshold ‘V2’, the electronic controller 14 detects occurrence of knocking within the cylinder 18. In such case, the electronic controller 14 generates a knock signal and a suitable action is taken based on the knock signal. It may be understood that the second predetermined knock threshold ‘V2’ is greater than the first predetermined knock threshold ‘VI’. Further, a value of the second predetermined knock threshold ‘V2’ is stored in the database 34, and may be retrieved therefrom.

[0025] FIG. 4 is a flowchart for a process 36 (or algorithm) that is stored in the electronic controller 14 to operate the engine 12. The process 36 begins at step 38. Further, the electronic controller 14, at step 40, determines if the temperature sensor 30 is working. In the engine system 10 of the present disclosure, the electronic controller 14 is in signal communication with the temperature sensor 30 to receive the temperature signal ‘Τ’. In the event of the failure of the temperature sensor 30, the electronic controller 14 may not receive any temperature signal ‘T’ or receive an invalid temperature signal ‘T’ which is usually out of an acceptable range, and thus the electronic controller 14 may conclude that the temperature sensor 30 is either not operational or malfunctioning. In some examples, the electronic controller 14 may further use some alternate references, such as temperature or pressure of exhaust gases exiting the corresponding cylinder 18, comparing the temperature signal ‘T’ with the output signal ‘S’, or other similar means to determine the faulty operations of the temperature sensor 30 in the engine 12.

[0026] In the event of the temperature sensor 30 working properly, the process 36 may move to step 42, and executes ‘ECU FUNCTION 1’. The ‘ECU FUNCTION 1 ’ includes detection of the occurrence or absence of the combustion event in the cylinder 18 using the temperature signal ‘Τ’ from the temperature sensor 30 and accordingly defining the parameters for operation of the engine 12.

[0027] Further, in the event of the failure of the temperature sensor 30, the process 36 moves to step 44. At step 44, the electronic controller utilizes the output signal ‘S’ from the knock sensor 32 as a reference for determining the occurrence of the combustion event in the combustion chamber 24 of the engine 12. More particularly, at step 44, the electronic controller 14 utilizes the output signal ‘S’ from the knock sensor 32 to determine the occurrence of the combustion event in the cylinder 18. As discussed above, for this purpose the electronic controller 14 compares the output signal ‘S’ with the first predetermined knock threshold ‘VI’. If the magnitude of the output signal ‘S’ is determined to be above the first predetermined knock threshold ‘VI’, then it is concluded that the combustion event has occurred in the cylinder 18 of the engine 12. In such a situation, the process 36 moves to step 46. At step 46, the electronic controller 14 executes ‘ECU FUNCTION 2’ which includes instructions to continue the operation of the engine 12.

[0028] However, if the magnitude of the output signal ‘S’ is determined to be below the first predetermined knock threshold ‘VI’, the absence of the combustion event in the cylinder 18 is detected by the electronic controller 14. Tn such a situation, the process 36 moves to step 48. At step 48, the electronic controller 14 generates the action signal ‘X’ which includes instructions to shut down or terminate the operation of the engine 12 in order to avoid damage to the engine 12. The process 36 terminates at step 50.

[0029] It should be noted that the action signal ‘X’ may also flag events such as, the cylinder 18 being cranked without occurrence of the combustion in the combustion chamber 24, for example in case the spark plug 25 associated with the cylinder 18 fails. Alternatively, the action signal ‘X’ may flag any other event where a component of the engine 12 fails that leads to the absence of the combustion event in the cylinder 18.

Industrial Applicability [0030] It is known that the temperatures inside the combustion chamber 24 may reach substantially high values during the operation of the engine 12. The temperature sensor 30, which at least has some of its components mounted in the combustion chamber 24 of the engine 12, is exposed to such high temperatures. Further, the temperature sensor 30 is exposed to moisture, dust, and other impurities in the combustion chamber 24 which may possibly damage the temperature sensor 30 and/or affect sensitivity of the temperature sensor 30.

[0031] As known, damage to the temperature sensor 30 may reduce operational precision of the temperature sensor 30, thus making the damaged temperature sensor 30 not reliable to be used for detecting the occurrence or absence of the combustion event. As the operating parameters of the engine 12 is determined based on the combustion parameters in the cylinder 18, this may lead to a situation where the operating parameters of the engine 12 may not be determined with sufficient accuracy which in turn may lead to damage to the engine 12, if the engine 12 is continued to be operated. As a consequence, the engine 12 is usually shut-down if it is determined that one or more temperature sensors 30 in the engine 12 have failed.

[0032] Further, the knock sensor 32 detects the knocking event in the engine 12. The term knocking is generally referred to as the metallic sound produced due to explosive detonation and auto-ignition of end gas in the combustion chamber 24, which is caused by improper ignition of fuel in the engine 12. Knocking generates acoustic vibrations which propagate throughout the engine block 16, and possibly other adjoining structures. The knock sensor 32 works on the principle of determining magnitude of such vibrations to detect the knocking in the engine 12. However, in the present disclosure, the output signal ‘S’, as generated by the knock sensor 32 for analysis and detecting the knock event, is also used as a reference for detecting the occurrence of the combustion event in the cylinder 18.

[0033] FIG. 4 illustrates a method 52 of operating the engine 12 in the event of failure of the temperature sensor 30. The method 52 of the present disclosure may be applicable to any gas powered engine or bi-fuel engine using a spark plug for ignition. At step 54, the method 52 includes associating the knock sensor 32 with the cylinder 18 to measure vibrations in the cylinder 18. At step 56, the electronic controller 14 receives the output signal ‘S’ from the knock sensor 32.

[0034] At step 58, the electronic controller 14 detects if the output signal ‘S’ is above the first predetermined knock threshold ‘VI’. At step 60, the electronic controller 14 determines the occurrence of the combustion event within the cylinder 18, based on the detection of the output signal ‘S’. At step 62, the electronic controller 14 terminates the operation of the engine 12, if the output signal ‘ S’ is below the first predetermined knock threshold ‘VI’.

[0035] Thus, in case of the failure of the temperature sensor 30 associated with the cylinder 18, the method 52 continues to allow the engine 12 to operate until a new temperature sensor 30 is installed. Accordingly, the method 52 eliminates loss of productivity of the engine 12, as the engine 12 does not stop operating due to failure of one or more components.

[0036] The method 52 allows constant monitoring of combustion events inside the cylinder 18 of the engine 12, and provides necessary feedback for reliable operation of the engine 12. The method 52 also provides information about other simultaneous component malfunction, such as malfunctioning of the spark plug 25, fuel supply, etc. for the respective cylinder 18 of the engine 12.

[0037] Further, the method 52 of the present disclosure allows effective and real time determination of working condition of the engine 12, and more particularly, the determination of the combustion events in the cylinders 18 of the engine 12. Further, the method 52 provides a cost effective approach for determination of the combustion events within the cylinder 18 as the method 52 makes use of the knock sensor 32 which is already installed in the engine 12. Further, the process or algorithm 36 that implements the method can be embedded within the ECU associated with the engine 12.

[0038] While aspects of the present disclosure have been particularly shown and described with reference to the embodiment above, it will be understood by those skilled in the art that various additional embodiments may be contemplated by the modification of the disclosed machines, systems, and methods without departing from the spirit and scope of what is disclosed. Such embodiments should be understood to fall within the scope of the present disclosure as determined based by the claim and any equivalents thereof.

Claims (2)

1. Claim What is claimed is:
2. 1. A method for operating an engine in an event of failure of at least one temperature sensor of the engine, wherein the at least one temperature sensor is adapted to measure combustion temperature within at least one cylinder of the engine, the method comprising: associating a knock sensor with the at least one cylinder, wherein the knock sensor is adapted to measure vibrations; receiving, by an electronic controller, an output signal from the knock sensor; detecting if the output signal is above a first predetermined knock threshold; determining occurrence of a combustion event within the at least one cylinder, based on the detection of the output signal; terminating the operation of the engine, if the output signal is below the first predetermined knock threshold.