Method and system for diagnosing thermostat faults in the engine with integrated diagnostic function

Abstract

A method for diagnosing a thermostat fault in an engine (10), comprising: determining when the engine (10) is providing high-performance operation (522) based on an engine performance parameter exceeding a high-performance operation threshold, the high-performance operation threshold being determined in response to an ambient air temperature value, and in response to the finding that the engine (10) is providing high-performance operation; determining the temperature (512) of an engine coolant; and determining that a thermostat has been found to be OK in response to the finding that the temperature (512) of the engine coolant exceeds a first temperature threshold (526).

Description

[0001] This patent application claims priority from the preliminary US patent application No. 61 / 723,719, filed on November 7, 2012, the contents of which are deemed to be fully incorporated herein by reference.

[0002] The present invention relates generally to engines with integrated diagnostic functions and, in particular, to the detection of thermostat faults in such engines. Specifically, this invention relates to a method for diagnosing thermostat faults in an engine with integrated diagnostic functions. The present invention further relates to a system comprising an internal combustion engine and integrated diagnostics.

[0003] Currently known methods for detecting a faulty thermostat only work during the initial engine start and / or can falsely detect a fault when the engine is operating at low power. Therefore, improvements in this technical area are needed.

[0004] The aforementioned objective is achieved by a method comprising the features in claim 1.

[0005] Preferred modifications and improvements of the method according to claim 1 are the subject of dependent claims 2 to 4.

[0006] The aforementioned objective is also achieved by a system with the features in claim 5.

[0007] Preferred modifications and improvements of the system according to claim 5 are the subject of dependent claims 6 to 10.

[0008] By narrowing down engine operation into two categories (low-load operation, where the coolant temperature may drop, and high-load operation, where the coolant temperature always remains above a minimum threshold), a diagnosis can be made to determine that when the engine is operating in the "high-load" range, the coolant temperature should either be rising or fully warmed up. If, during "high-load" operation, the coolant temperature either drops or stabilizes at a temperature significantly below the thermostat opening temperature, then it can be concluded that the thermostat is either partially or fully stuck open, has been tampered with, or has been completely removed.

[0009] The following is a description of preferred, but not limiting, embodiments of the invention with reference to the drawings. The drawings show:

[0010] Fig. 1 a schematic representation of a first exemplary embodiment of the present disclosure.

[0011] Fig. 2. Coolant temperature development of an intact engine.

[0012] Fig. 3A illustrative data of a coolant temperature for an engine with a properly functioning thermostat under low ambient temperature and load conditions.

[0013] Fig. 3B illustrative data of a coolant temperature for an engine with a faulty thermostat under high load conditions.

[0014] Fig. 4 A schematic flowchart for the operation of a thermostat fault detection algorithm according to one embodiment.

[0015] Fig. 5 a schematic diagram of a device for diagnosing a thermostat.

[0016] The following description is intended to enable a person skilled in the art to manufacture and use the invention and is provided in the context of a patent application and its requirements. Various modifications of the preferred embodiments and of the general principles and features described herein will be readily apparent to a person skilled in the art. The present invention is therefore not limited to the embodiments shown, but should be viewed within the broadest possible scope of application that corresponds to the principles and features described herein.

[0017] Referring now to Fig. 1. Can an internal combustion engine 10 with a first exemplary embodiment of the present publication, an engine body or block 12 , a coolant circuit 14 , to allow coolant or a coolant to pass through the engine body 12 to operate a pump system 16, to circulate the coolant through the engine body 12 to pump, an exhaust system 18 and a tax system 20 exhibit.

[0018] The coolant circuit 14 can a radiator 24 which may include a heat exchanger or cooler. The exhaust system 18 can an exhaust manifold 28 and a downstream flow path 32 exhibit the tax system 20 can a control module 34 , a wiring harness 36 and a temperature sensor 40 exhibit.

[0019] The control module 34 It could be an electronic control unit of an electronic control module (ECM) that controls the engine's performance. 10 The control module can monitor or monitor other vehicle conditions. 34This can be a single processor, a distributed processor, an electronic equivalent of a processor, or any combination of the aforementioned elements, or even software, electronic memory, fixed lookup tables, or the like. The control module 34 certain engine components 10 via a wiring harness 36 connect, although such a connection can also be made by other means, including a wireless system. The control module 34 It can have a digital or analog circuit.

[0020] In a system and a method according to one embodiment, by limiting engine operation to two categories (low-load operation, in which the coolant temperature may decrease, and high-load operation, in which the coolant temperature always remains above a minimum threshold), a diagnosis can be made to determine that when the engine is operating in the "high-load" range, the coolant temperature should either be rising or fully warmed up. If, in "high-load" operation, the coolant temperature either decreases or stabilizes at a temperature significantly below the thermostat opening temperature, then it can be concluded that the thermostat is either partially or fully stuck open, has been tampered with, or has been completely removed.

[0021] A system that uses a thermostat fault detection algorithm according to the present invention can take the form of a complete hardware implementation, an implementation including computer instructions stored in non-volatile, computer-readable memory, or an implementation including a mixture thereof.

[0022] Furthermore, the thermostat fault detection algorithm can take the form of a computer program product accessible via a computer-usable or computer-readable medium that provides program code used by or in conjunction with a computer or any command-line execution system. For the purposes of this description, a computer-usable or computer-readable medium can be any device that contains, stores, communicates, distributes, or transports the program used by or in conjunction with a computer, device, or institution.

[0023] The medium can be an electronic, magnetic, optical, electromagnetic, infrared, or semiconductor system (or device or arrangement), or a propagation medium. Examples of a computer-readable medium include, but are not limited to, semiconductor or solid-state memory, magnetic tape, removable computer disks, random access memory (RAM), read-only memory (ROM), magnetic hard disks, and optical storage media. Current examples of optical storage media include DVDs, compact disk read-only memory (CD-ROM), and compact disk read / write (CD-R / W). To explain the features of the present invention in more detail, a description will now follow in conjunction with the accompanying drawings.

[0024] An intact engine that has cooled down overnight and is operated with a significant work cycle will exhibit a coolant temperature development similar to the line sections. 101 – 102 in Fig. Show 2. Line segment 101 This shows a portion of the coolant temperature as it warms up, when the fuel burned in the cylinders heats the coolant in the engine block casing. At one point 104 The thermostat opens and regulates the engine temperature by allowing coolant to flow to the vehicle radiator (coolant-ambient temperature heat exchanger). At this point, a functioning thermostat will maintain a largely constant coolant temperature for most of the remaining vehicle operating cycles (line segment). 102 ) maintain.

[0025] If the thermostat remains open, the coolant temperature can develop as described in... 103This may or may not be a sign of a faulty thermostat.

[0026] Faulty operating conditions were understood in the section of the line. 101 To successfully diagnose the area shown, but up to that point had no thermostat diagnosis available in the area defined by the line segment. 102 depicted area. The difficulty of detecting a fault in this operating state 103 The key finding is that a diesel engine (which moves up and down by half its engine displacement in ambient air with each crankshaft revolution) inherently tends to reach a significantly lower engine block temperature when idling in cold ambient air temperatures. This means that an intact engine operated at low power (low heat dissipation to the coolant) will exhibit a development similar to… 103will show, even though the thermostat is working as intended.

[0027] To distinguish between a normal coolant temperature drop and an unexpected coolant temperature drop, one embodiment of the present invention uses either the fuel supply burned in the cylinder or an estimated torque generation as inputs for the diagnosis. Additionally or alternatively, the diagnosis uses the ambient air temperature as an input.

[0028] Referring to Fig. 3A's diagnostic function determines a pass / fail decision when the coolant temperature exceeds a calibrated threshold. Referring to Fig. 3B identifies a fault in the diagnosis if the coolant temperature does not rise during a prolonged period of high fuel supply or high torque and / or an ambient temperature above the calibrated threshold.

[0029] Referring together to Fig. 3A and Fig. 3B the coolant temperature should rise as expected or exceed a fixed threshold. 105 ; 205 have been exceeded if the coolant temperature is lower than a threshold value 105 ; 205 (based, for example, on the thermostat regulating temperature used by the engine) occurs when the fuel supply / torque exceeds a calibrated threshold. 202 The diagnostic function detects a fault and diagnoses that the thermostat is faulty. This occurs when the coolant temperature does not rise during a prolonged period of high fuel supply or high torque, and / or when the ambient temperature exceeds a calibrated threshold. 204 is defective. If the coolant temperature exceeds a calibrated threshold. 105 ; 205If the threshold has been exceeded, the diagnostic function makes a pass / fail decision. 203 fixed. Referring to Fig. Section 4 describes this algorithm in detail.

[0030] Fig. Figure 4 is a flowchart for the operation of a thermostat fault detection algorithm according to one embodiment. After the thermostat fault algorithm has first been started (step 4), the following steps are performed: 302 ), is then determined (step 304 ) whether the sensors are intact. An exemplary procedure to determine whether the sensors are intact involves ascertaining whether a relevant sensor is currently in a faulty state, and / or whether a replacement sensor is permissible to proceed with the diagnostic procedure if the primary sensor is faulty.

[0031] If it is determined that the sensors are intact (step 304 ), is then determined (step 306), whether the coolant temperature is below a threshold value. If the coolant temperature is not below this threshold, then the diagnostic function displays (step ) 314 ) that the thermostat is working properly, and returns to step 302 back.

[0032] The process 306 It may additionally or alternatively include a test (not shown) to determine whether an ambient temperature is below a threshold. In certain embodiments, a sufficiently high ambient temperature can ensure a coolant temperature reading high enough to mask a faulty thermostat. In certain embodiments, the process can 306The system will be checked to determine whether a sensor previously found to be correct remains in a correct state, and to establish that a sensor previously found to be faulty will now be found to be correct if the ambient temperature is also below a threshold.

[0033] If, however, it is determined that the coolant temperature is below the threshold, then (step 308 ), whether the motor's torque is less than a predefined threshold. If the motor's torque is less than a predefined threshold, then (step ) 310 ), whether the coolant temperature rises. If the coolant temperature rises, then a fault timer is decremented (step 1). 312 ), and the process returns to the beginning (step 302 ).

[0034] If the coolant temperature exceeds a threshold value (step 306), the thermostat fault diagnosis is passed (step 314 ), and the process is complete and / or returns to the beginning (step 302 Once the diagnostic process is complete, it can be repeated at any selected interval, including at least periodically, in response to a key event, in response to a driving detection event, in response to the engine speed load entering a specific range (e.g., a high load or fuel supply range), and / or further, in response to the engine coolant falling below a threshold when the engine speed load enters the specified range.

[0035] If it is determined that the coolant temperature is below the threshold (step 306 ) and the torque is above its threshold value (step 308 ), then the error timer is reduced (step 316), and the process returns to the beginning (step 302 If it is determined that the torque is below the threshold (step 308 ) and the coolant temperature does not rise (step 310 ), then the error timer is increased (step 318 ).

[0036] If the error timer exceeds a threshold value (step 320 ), then an error is detected (step 322 If the error timer is below the threshold, the process returns to the beginning (step ). 302 In certain embodiments, an error value can be increased if the value of the error timer exceeds the threshold (process). 320), and if the error value is increased a predetermined number of times, a thermostat fault is detected. Each of the "Diagnosis Passed" operations described here can reset the error value and / or reduce the error value to a sensor value deemed correct.

[0037] By narrowing down engine operation into two categories (low-load operation, where the coolant temperature may drop, and high-load operation, where the coolant temperature always remains above a minimum threshold), a diagnosis can be made to determine that when the engine is operating in the "high-load" range, the coolant temperature should either be rising or fully warmed up. If, during "high-load" operation, the coolant temperature either drops or stabilizes at a temperature significantly below the thermostat opening temperature, then it can be concluded that the thermostat is either partially or fully stuck open, has been tampered with, or has been completely removed.

[0038] Further exemplary embodiments are described below.

[0039] In certain embodiments, a system includes a control unit (e.g., control module).34 ) which is configured to perform certain operations for diagnosing a thermostat. In certain embodiments, the control unit is part of a processing subsystem, including one or more computing devices with storage, processing, and communication capabilities. The control unit may be a single device or a distributed device, and the functions of the control unit may be executed by devices and / or as computer instructions on a non-volatile, computer-readable storage medium.

[0040] In certain embodiments, the control unit comprises one or more modules configured to functionally execute the control unit's operations. In certain embodiments, the control unit comprises an engine load determination module, a thermostat diagnostic module, and / or a test state module. The description herein, including modules, emphasizes the structural independence of the control unit's aspects and illustrates a grouping of the control unit's operations and responsibilities. Other groupings performing similar overall operations are to be understood as belonging to the scope of the present invention. Modules may be implemented in devices and / or as computer instructions on a non-volatile, computer-readable storage medium, and modules may be distributed across multiple devices or computer-based components. More detailed descriptions of certain embodiments of control unit operations are contained in the reference to Fig. 5. Referenced section.

[0041] Exemplary and non-limiting module implementation elements include sensors providing any value identified herein, sensors providing a value that is a precursor to a value identified herein, data link and / or network equipment, including integrated communication circuits, crystal oscillators, communication links, cables, twisted pairs, coaxial cabling, shielded cabling, transmitters, receivers, and / or transmitter-receivers, logic circuits, hard-wired logic circuits, reconfigurable logic circuits in a specific permanent state configured according to the module specification, any actuator, including at least one electric, hydraulic, or pneumatic actuator, a solenoid, an operational amplifier, analog controls (springs, filters, integrators, adders, dividers, gain elements).and / or digital controls.

[0042] Certain processes described herein include procedures for determining one or more parameters. Determining, as used herein, includes receiving values ​​by means known to a person skilled in the art, including at least receiving values ​​from a data link or network communication, receiving an electronic signal indicating the value (e.g., a voltage, frequency, current, or PWM signal), receiving a computer-generated parameter indicating the value, reading the value from a memory on a non-volatile, computer-readable storage medium, receiving the value as a time-of-flight parameter by means known to a person skilled in the art, and / or receiving a value from which the determined value can be calculated, and / or referencing a default value that is designated as the parameter value.

[0043] An exemplary system10 ( Fig. 1) has an internal combustion engine 12 with a thermostat (not shown) that allows selective coolant flow through the engine 12 enables. The system 10 It further features a coolant temperature detection device that provides a coolant temperature reading. An example of such a device includes a temperature sensor that detects the coolant temperature at the engine block or at a location where the coolant temperature within the engine block can be estimated or inferred.

[0044] An exemplary system further includes a control unit configured to functionally execute operations for diagnosing the thermostat. The exemplary control unit includes a number of modules configured to functionally execute the control unit's operations.

[0045] An exemplary system 10 points the engine12 This is a compression-ignition engine, which can also be a direct-injection engine. Compression-ignition engines do not require a specific air-fuel mixture for combustion to occur in the combustion chamber. Consequently, under numerous operating conditions, compression-ignition engines operate with excess air to improve power density, torque capacity, and / or emissions. At low engine loads, the amount of excess air can be high, resulting in low exhaust gas and coolant temperatures. A knowledgeable person who has the benefit of the disclosures here will recognize that thermostat diagnostics can be particularly advantageous for a compression-ignition engine.

[0046] Referring to Fig. 5 will be an example control unit 34 schematically represented. The control unit 34 features an engine load detection module 502This determines whether the engine is capable of high-performance operation. 522 provides an example engine load determination module. 502 determines an engine performance parameter, for example, an engine output torque 508 and / or motor output power 510 , and determines whether the engine performance parameter has a high-performance operating threshold. 518 exceeds.

[0047] The high-performance operating threshold 518 This can vary with the engine condition; for example, the torque threshold can vary with engine speed. Any engine operating condition that affects the coolant temperature can be used as an engine performance parameter, such as, but not limited to, EGR rate, EGR cooler bypass state, exhaust manifold temperature, intake manifold temperature, and / or VGT position. In certain embodiments, the engine load determination module determines 502Furthermore, whether the engine can handle high-performance operation 522 in response to the ambient air temperature value. In certain embodiments, the engine load detection module highlights 502 the engine power threshold 518 in response to a reduced ambient air temperature 514 a reduced ambient air temperature value 514 This results in a lower engine output temperature and a lower coolant temperature. 512 At a lower ambient temperature value 514 A higher engine power rating is required to achieve the same coolant temperature. 512 to achieve, and in certain embodiments the high-performance operating threshold is 518as a reaction to the reduced ambient air temperature, it is adjusted upwards. An expert who has the benefit of the disclosures herein will have expected, when considering a particular system, that coolant temperature values ​​for various engine operating conditions are readily available, or that such values ​​can be obtained from a standard data generation process carried out in the usual manner. Consequently, the selection of a high-performance operating threshold is 518 a mechanical step for an expert who has the advantage of the disclosures contained therein.

[0048] The exemplary control unit 34 It also features a thermostat diagnostic module. 506 up, which determines when the engine 12 a high-performance operation 522 provides, and in response to the finding that the engine 12 a high-performance operation 522provides, determines that the thermostat has been found to be correct (THERMOSTAT CORRECT / FALSE) 516 as CORRECT), in response to the fact that the coolant temperature value 512 a first temperature threshold 526 exceeds.

[0049] In certain embodiments, the control unit 34 still a test state module 504 up, which determines that the engine 12 in a low-power operation 520 is located, and prevents the diagnostic function from determining whether the thermostat is responding to low-power operation. 524 was found to be correct. An exemplary system has an ambient air temperature measuring device that provides an ambient air temperature value. 514 determined, and wherein the test state module 504 determines whether the ambient air temperature value 514 lower than a second temperature threshold 530is. The test state module 504 The diagnostic function continues to be prevented from determining whether the thermostat has been found to be correct, in response to the ambient air temperature value. 514 lower than the second temperature threshold 530 is.

[0050] An example control unit 34 The thermostat diagnostic module continues to show 506 on, which is a reaction to the fact that the engine is operating at high speed 522 provides, further notes that the thermostat was found to be faulty, and further notes in response to the fact that the coolant temperature 512 lower than a third threshold 528is and / or the coolant temperature value does not increase by a calibratable amount within a calibratable time. The calibratable amount and duration of the expected coolant temperature increase can be based on engine operating conditions and / or ambient conditions. An example control unit 34 The thermostat diagnostic module indicates 506 which further notes that the thermostat, in response to a fourth threshold, 532 exceeding ambient temperature value 514 , was found to be faulty.

[0051] The following schematic diagram provides an illustrative embodiment of methods for diagnosing a thermostat. The operations shown are examples only and may be combined or separated, added or removed, or rearranged in whole or in part, unless expressly stated otherwise herein. Certain operations shown may be implemented by a computer executing a computer program on a non-volatile, computer-readable storage medium, the computer program comprising instructions that cause the computer to perform one or more operations or to issue instructions to other devices to perform one or more operations.

[0052] An exemplary procedure for diagnosing a thermostat fault in an engine includes the process of determining when the engine is operating at high power. In response to the determination that the engine is operating at high power, the procedure includes procedures to determine the temperature of an engine coolant and to establish that a thermostat has been found to be functioning correctly in response to the determination that the engine coolant temperature exceeds an initial temperature threshold. An exemplary procedure further includes a procedure to prevent the thermostat fault from being diagnosed in response to the determination that the engine is operating at low power. An exemplary high-power operation involves operation with high torque and / or high power. An exemplary low-power operation involves operation with low torque and / or low power.One exemplary procedure includes a process to avoid diagnosing the thermostat fault in response to the finding that the ambient temperature value is lower than a second temperature threshold.

[0053] An exemplary procedure includes a process to determine that the thermostat has been found to be faulty in response to the engine providing high-performance operation, as well as in response to the coolant temperature being below a third threshold and / or the coolant temperature not increasing by a calibratable amount within a calibratable time. An exemplary control unit 34 The thermostat diagnostic module indicates 506 which further notes that the thermostat, in response to a fourth threshold, 532 exceeding ambient temperature value 514 , was found to be faulty.

[0054] Although the present invention has been described in accordance with the embodiments shown, a person skilled in the art will readily recognize that variations of the embodiments could exist and that such variations would be within the meaning and scope of the present invention. Accordingly, a person skilled in the art can make many modifications without departing from the meaning and scope of the present invention.

Claims

[1] Method for diagnosing a thermostat fault in an engine, comprising: Determine when the engine is providing high-performance operation, and in response to the finding that the engine is providing high-performance operation: determine the temperature of an engine coolant, and determine that a thermostat has been found to be OK in response to the finding that the temperature of the engine coolant exceeds an initial temperature threshold. [2] Method according to claim 1, further comprising avoiding the diagnosis of a thermostat fault in response to the finding that the engine is in low-power operation, and / or further comprising avoiding the diagnosis of a thermostat fault in response to the finding that an ambient temperature value is lower than a second temperature threshold value. [3] Method according to claim 1 or 2, wherein the high-power operation comprises at least one of the following: high-torque operation and high-power operation, and wherein the low-power operation comprises at least one of the following: low-torque operation and low-power operation. [4] A method according to any of the preceding claims, further comprising determining that the thermostat has been found to be faulty in response to the engine providing high-performance operation, and further in response to at least one of the following: the coolant temperature is lower than a third threshold and the coolant temperature does not increase by a calibratable amount within a calibratable period, wherein, preferably, the method further comprises determining that the thermostat has been found to be faulty in response to the ambient temperature exceeding a fourth threshold. [5] System, comprehensive: an internal combustion engine with a thermostat designed to selectively allow coolant flow through the engine; a coolant temperature measuring device, designed to provide a coolant temperature reading; a control unit, comprehensive: a motor load detection module, designed to determine whether the motor is providing high-performance operation; a thermostat diagnostic module, designed to determine when the engine is providing high-performance operation, and in response to the determination that the engine is providing high-performance operation, to determine that the thermostat has been found to be correct, in response to the coolant temperature value exceeding an initial temperature threshold. [6] System according to claim 5, wherein the control unit further comprises a test state module configured to determine that the engine is in low-power operation and to prevent the determination of whether the thermostat has been found to be correct in response to low-power operation of the engine, and / or further comprising an ambient air temperature detection device to determine an ambient air temperature value, and a test state module configured to determine whether the ambient air temperature value is lower than a second temperature threshold value, and to prevent the determination of whether the thermostat has been found to be correct in response to the ambient air temperature value being lower than the second temperature threshold value. [7] System according to claim 5 or 6, wherein the high-performance operation comprises at least one of the following: high-torque operation and high-power operation, and wherein the low-performance operation comprises at least one of the following: low-torque operation and low-power operation. [8] System according to any one of claims 5 to 7, wherein the thermostat diagnostic module is further configured to determine that the thermostat has been found to be faulty in response to the engine providing high-performance operation, and furthermore in response to at least one of the following: the coolant temperature is lower than a third threshold value and the coolant temperature does not increase by a calibratable amount within a calibratable period of time, wherein, preferably, the engine load detection module is further configured to determine whether the engine is providing high-performance operation in response to the ambient temperature value. [9] System according to any one of claims 5 to 8, further comprising raising an engine power threshold in response to a reduced ambient air temperature value. [10] System according to any one of claims 5 to 9, wherein the engine is a compression ignition engine, and wherein the engine is preferably a direct injection engine.

Images