JP2011196220A - Oil abnormality diagnosis device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To diagnose oil by differentiating the degradation anomaly and the viscosity anomaly.SOLUTION: The device is used for diagnosing abnormality of oil, which is a lubricant of an internal combustion engine. The device detects or estimates oil viscosity while it detects or estimates oil degradation. The device determines either degradation anomaly or viscosity anomaly in the oil based on the degradation level or viscosity level that are detected or estimated.

Description

  The present invention relates to an apparatus for diagnosing abnormality of oil as lubricating oil of an internal combustion engine.

  As a technique related to this type of apparatus, there is a technique described in Patent Document 1 conventionally. In this case, the viscosity of the lubricating oil in use is detected, and when the viscosity exceeds a preset viscosity limit value, an instruction to withdraw the used oil and supply new oil is issued.

Japanese Utility Model Publication No. 4-52515

  By the way, most of the prior arts correlate the viscosity of the oil with the degree of deterioration, and determine that the oil has become abnormally deteriorated when the viscosity becomes higher than a predetermined value.

  However, the viscosity of oil and the degree of deterioration are not necessarily correlated. For example, when a user replenishes a new oil for high temperature with a viscosity higher than that of standard oil at the time of oil replacement, the oil is naturally not deteriorated. However, the conventional technique erroneously determines that the oil has deteriorated in this case as well. Further, it has been found from the knowledge of the present inventors that when the oil deteriorates, the viscosity may increase or decrease.

  Therefore, the present invention has been made in view of such circumstances, and an object of the present invention is to provide an oil abnormality diagnosis device capable of distinguishing and diagnosing oil deterioration abnormality and viscosity abnormality.

According to one aspect of the invention,
An apparatus for diagnosing an abnormality of an oil which is a lubricating oil of an internal combustion engine,
A deterioration level acquisition means for detecting or estimating the deterioration level of the oil;
Viscosity acquisition means for detecting or estimating the viscosity of the oil;
A determination unit that distinguishes between the deterioration degree of the oil and the presence or absence of a viscosity abnormality based on the degree of deterioration detected or estimated by the deterioration degree acquisition unit and the viscosity detected or estimated by the viscosity acquisition unit;
An oil abnormality diagnosis device is provided.

  Preferably, when the determination unit determines that there is at least one of a deterioration abnormality and a viscosity abnormality, the oil abnormality diagnosis device has a strong warning and a weak warning depending on a combination of the deterioration abnormality and the viscosity abnormality. A warning means for selectively issuing any one of the above.

  Preferably, the warning unit issues a strong warning when the determination unit determines that both the deterioration abnormality and the viscosity abnormality are present.

  Preferably, the warning means issues a weak warning when the determination means determines that there is a viscosity abnormality but determines that there is no deterioration abnormality.

  Preferably, the warning means issues a strong warning when the determination means determines that there is a viscosity abnormality.

  Preferably, the warning means issues a weak warning when the determination means determines that there is a deterioration abnormality but determines that there is no viscosity abnormality.

  Preferably, the viscosity acquisition means includes a hydraulic switch provided at a predetermined position of the oil circulation path, and estimates the viscosity of the oil using an output signal of the hydraulic switch.

  According to the present invention, an excellent effect is exhibited that it is possible to make a diagnosis by distinguishing between oil deterioration abnormality and viscosity abnormality.

1 is a perspective view showing a lubrication system for an internal combustion engine according to an embodiment of the present invention. It is a block diagram which shows the structure of the control system of an internal combustion engine. It is a block diagram which shows the model regarding the 2nd method of oil viscosity estimation. It is a flowchart regarding the 1st example of abnormality diagnosis processing. It is a flowchart regarding the 2nd example of abnormality diagnosis processing.

  DESCRIPTION OF EMBODIMENTS Hereinafter, embodiments for carrying out the present invention will be described with reference to the accompanying drawings.

  FIG. 1 shows a lubrication system for an internal combustion engine according to this embodiment. The oil flow in this lubrication system is indicated by arrows in the figure. The internal combustion engine of this embodiment is mounted on a vehicle.

  As illustrated, the internal combustion engine (engine) 1 includes an oil pump 2 driven by a crankshaft (not shown). The oil pump 2 sucks the oil stored in the oil pan 3 through the oil strainer 4 and discharges the oil toward the oil filter 5. The oil that exits the oil filter 5 flows into a main oil hole 7 that extends in the crankshaft direction of the cylinder block 6.

  Oil is distributed from the main oil hole 7 to each lubricating part. For example, the oil is distributed to the oil delivery pipe 10 disposed at the uppermost part in the valve operating chamber defined by the cylinder head 8 and the head cover 9. The oil in the oil delivery pipe 10 is supplied dropwise to a plurality of longitudinal positions of an intake camshaft and an exhaust camshaft (both not shown).

  The oil in the main oil hole 7 is divided into a plurality of cam journals 11 that support each camshaft, a plurality of crank journals 12 that support the crankshaft, a crankpin (not shown), an oil jet 13 and a chain tensioner 14. The variable valve timing mechanism control oil control valve (OCV) 15 and the lash adjuster 16 are distributed to the respective parts.

  The main oil hole 7 is provided with an oil deterioration sensor 20 for detecting the degree of oil deterioration. As the oil deterioration sensor 20, various sensors such as an optical sensor and an electric resistance sensor can be used. As an optical sensor, for example, one disclosed in JP-A-5-107182 is known, and as an electrical resistance type sensor, for example, one disclosed in JP-A-11-270787 is known.

  In the optical sensor, the light emitted from the light emitting part passes through the oil and reaches the light receiving part. The light receiving unit outputs a signal proportional to the illuminance or the amount of light received. In the electrical resistance sensor, a signal proportional to the electrical resistance value between a pair of electrodes immersed in oil is output. The electronic control unit (ECU) detects the degree of oil deterioration based on the output signal. Hereinafter, it is assumed that the output of the oil deterioration sensor 20 increases as the degree of oil deterioration increases.

  The main oil hole 7 is provided with a hydraulic switch 30 that detects a rise in hydraulic pressure immediately after the engine is started. The hydraulic switch 30 is configured to be turned on when the hydraulic pressure at the installation position exceeds a predetermined value, and to be turned off otherwise.

  FIG. 2 shows the configuration of the control system of the engine 1. The ECU 100 as the control means includes a CPU, a ROM, a RAM, an input / output port, a storage device, and the like, all not shown. In addition to the oil deterioration sensor 20 and the hydraulic switch 30, the ECU 20 includes a crank angle sensor 41 that detects the crank angle of the engine 1, a water temperature sensor 42 that detects the cooling water temperature of the engine 1, and an outside air temperature sensor that detects the outside air temperature. 43, each signal from an oil level sensor 44 for detecting the oil level in the oil pan 3 and a vehicle speed sensor 45 for detecting the vehicle speed are input. Further, the ECU 20 outputs a signal to a warning lamp 51 and a multipurpose display 52 provided in the driver's seat of the vehicle.

  According to such a configuration, the oil deterioration sensor 20 and the ECU 100 form a deterioration degree acquisition unit that detects the deterioration degree of the oil that is currently used in the engine 1. ECU 100 determines that there is an oil deterioration abnormality in which the oil has deteriorated to the extent that oil replacement is necessary when the detected degree of oil deterioration is greater than a predetermined value, and otherwise determines that there is no oil deterioration abnormality.

  The oil deterioration level may be estimated without being directly detected, or the presence or absence of an oil deterioration abnormality may be determined based on the estimated oil deterioration level. For example, the ECU 100 estimates the degree of oil deterioration based on the distance traveled since the previous oil change. The fact of oil change can be automatically detected from the output of the oil level sensor 44. That is, the ECU 100 detects that the oil has been changed when the oil level detected by the oil level sensor 44 once falls below a predetermined value and then exceeds the predetermined value. Note that the fact of oil change may be detected using a signal of a reset switch of an odometer operated by a user or the like. On the other hand, the ECU 100 detects the travel distance of the vehicle by sequentially integrating the vehicle speeds detected by the vehicle speed sensor 45.

  Alternatively, the ECU 100 can estimate the degree of oil deterioration based on the history of engine operating conditions from the previous oil change to the current time.

  On the other hand, according to the above configuration, the hydraulic switch 30 and the ECU 100 serve as a viscosity acquisition unit that estimates the viscosity of oil that is currently used in the engine 1. When the estimated oil viscosity is greater than a predetermined value, ECU 100 determines that there is an oil viscosity abnormality in which the oil is higher than a predetermined allowable viscosity (typically the viscosity of standard oil), and so on. If not, it is determined that there is no oil viscosity abnormality.

  As described above, in the present embodiment, the determination is made by distinguishing the presence or absence of the oil deterioration abnormality and the viscosity abnormality. This makes it possible to make a diagnosis by distinguishing between oil deterioration abnormality and viscosity abnormality.

  Here, the deterioration degree and viscosity of oil are different concepts, and there is not necessarily a correlation between them. As described above, even if the oil is deteriorated, the viscosity may increase or decrease, and the new high temperature oil is not deteriorated but has a high viscosity. Types of oil deterioration include excessive dissolution of water, SOx, NOx and carbon into at least one oil, or deterioration of a lubricant in the oil.

  Most of the prior arts correlate the degree of deterioration of the oil with the viscosity, and determine that the oil has become abnormally deteriorated when the viscosity becomes higher than a predetermined value. However, if this is the case, when the user intentionally replenishes high-viscosity new high-temperature oil at the time of oil replacement, it is erroneously determined that the oil has deteriorated.

  In the present embodiment, the viscosity is estimated or detected separately from the degree of deterioration of the oil, and the presence or absence of viscosity abnormality is determined solely based on this viscosity, so that such erroneous determination and erroneous diagnosis can be prevented.

By the way, if high-viscosity oil is used, fuel consumption deteriorates and CO ₂ emission increases. In recent years, there has been an increasing demand for reducing CO ₂ emissions from the viewpoint of preventing global warming. Correspondingly, there is a movement in the field of automobiles to restrict the viscosity of oil used to a certain value or less. Based on this situation, in the present embodiment, the oil viscosity abnormality can be detected alone on-board.

  The oil viscosity can be directly detected by providing an oil viscosity sensor. However, in this embodiment, in order to avoid an increase in the number of parts, the oil viscosity is estimated by using a signal of the hydraulic switch 30 that inherently detects the hydraulic pressure rising immediately after the start.

  The first method for estimating the oil viscosity will be described below. The first method is a method for estimating the oil viscosity based on the time from when the engine is started until the hydraulic switch 30 is turned on. This time is usually about 0.3 to 1 second.

  The ECU 100 detects a time (on time) from the time when the engine is in a complete explosion state during cranking of the engine to the time when the hydraulic switch 30 is turned on. If the detected ON time is longer than the predetermined time, the oil is determined to have a high viscosity, and if the ON time is not longer than the predetermined time, the oil is determined to have a low viscosity or a standard viscosity.

  As shown in FIG. 1, an oil distribution path having a predetermined length exists between the oil pump 2 and the installation position of the hydraulic switch 30. Even when the engine is in a complete explosion state and the oil pump 2 is substantially activated, it takes a certain time for the hydraulic pressure at the installation position of the hydraulic switch 30 to rise.

  Further, the time until the hydraulic pressure rises tends to increase as the oil viscosity increases and decreases as the oil viscosity decreases. Therefore, by comparing the time with a predetermined time, it is possible to determine whether the oil viscosity is high or low.

  Preferably, ECU 100 sets a predetermined time based on the oil temperature immediately before cranking. Since the oil viscosity is higher as the oil temperature is lower, the predetermined time is set to a larger value. This compensates for changes in the oil temperature and makes it possible to estimate the oil viscosity with higher accuracy. Here, the oil temperature may be directly detected by the oil temperature sensor, but in this embodiment, the value of the water temperature detected by the water temperature sensor 42 is substituted to avoid an increase in the number of parts.

  Next, a second method for estimating the oil viscosity will be described. In this second method, the lubrication system as shown in FIG. 1 is modeled to estimate the oil pressure at a plurality of positions, in particular, the oil pressure at the position where the hydraulic switch is installed, and the oil viscosity to give the actually detected on-time. This is an estimation (or identification) method.

  FIG. 3 schematically shows a model of the lubrication system. The illustrated example shows only a part of the lubrication system shown in FIG. 1 including important ones.

  In the drawing, the hydraulic pressure at each position i (i = 1, 2, 3,... 20) of the lubrication system is denoted by Pi. 2A is a relief valve circuit of the oil pump 2, and 5A is a bypass valve circuit of the oil filter 5. The main oil hole 7 is divided into positions of i = 5 to 13 from the upstream side to the downstream side. Here, the position where i = 7 is the installation position of the hydraulic switch 30.

  In the following description, the hydraulic pressure at each position i is represented by P (i) for convenience. The oil pressure P (i) at each position i is calculated by the ECU 100 from the following equation (1).

k is the bulk modulus, ΔQ is the oil flow rate at each position i, and V is the volume at each position i.
The ECU 100 obtains the bulk modulus k from a previously stored map (which may be a function, the same applies below) based on the oil temperature immediately before cranking, and uses this value for the above calculation. The ECU 100 uses a value that is preset and stored based on the specifications of the lubrication system as the volume V of each position i.

  Next, the oil flow rate ΔQ is calculated by the ECU 100 from the following equation (2).

  α is a predetermined constant, ΔP is the differential pressure between the upstream end and the downstream end of each position i, and μ is the oil viscosity. The constant α is preset based on the specifications of the lubrication system and stored in the ECU 100.

  On the other hand, the oil flow rate ΔQp at the oil pump outlet is calculated by the ECU 100 from the following equation (3).

  Kp is a coefficient determined according to the oil viscosity μ, Ne is the engine rotation speed, and R is a speed ratio of the oil pump rotation speed to the engine rotation speed.

  The ECU 100 calculates the engine speed Ne based on the pulse signal from the crank angle sensor 41, and uses this value for the above calculation. The value of the speed ratio R is stored in the ECU 100.

  Since the oil pump outlet pressure is limited to a predetermined relief pressure or less by the relief valve circuit 2A, the oil pump outlet oil flow rate ΔQp is also limited to a value corresponding to the relief pressure or less. The oil pressure P (3) at the position immediately after the oil pump is limited to a relief pressure or less.

  Based on the above, the ECU 100 first detects an actual on-time from when the engine is in a complete explosion state to when the hydraulic switch 30 is turned on. During this on-time, the ECU 100 stores the values of parameters (engine rotational speed Ne, etc.) other than the oil viscosity μ necessary for estimating the oil viscosity in a buffer every predetermined calculation cycle.

  Next, the ECU 100 inputs a temporary value (for example, 0.5 (Pa · s)) as the oil viscosity μ, and formulas (1) to (3) and the value of each parameter for each calculation cycle stored in the buffer. From this, the temporal transition of the oil pressure P (i) at each position, that is, the oil pressure P (i) at each position for each calculation cycle is estimated. At this time, the ECU 100 calculates the hydraulic pressure P (3) at the position immediately after the oil pump from the formulas (1) and (3), and at each of the downstream positions (i = 2, 3,... 20). The hydraulic pressure P (i) is calculated sequentially from the equations (1) and (2).

  Next, another value (for example, 0.6 (Pa · s)) is input as the oil viscosity μ, and the above calculation is executed again. Thus, the process of calculating by changing the oil viscosity μ is repeated, and the temporal transition of the oil pressure P (i) at each position corresponding to each oil viscosity is estimated.

  From the temporal transition of the hydraulic pressure P (i) at each position, only the temporal transition of the hydraulic pressure P (7) at the hydraulic switch installation position is extracted. Then, at the time when the actual on-time has elapsed, only the temporal transition in which the hydraulic pressure P (7) is equal to or closest to the hydraulic switch response pressure (pressure at which the hydraulic switch 30 is turned on) is extracted. The temporary oil viscosity μ giving this temporal transition is determined as the viscosity of the oil currently used. That is, the temporary oil viscosity μ giving the closest calculation result among the plurality of calculation results performed by changing the temporary oil viscosity μ is estimated as the actual oil viscosity μ.

  This second method is more advantageous than the first method in that it can estimate only the absolute value of the oil viscosity, rather than estimating only the oil viscosity as in the first method.

  Neither the first method nor the second method requires a hydraulic pressure sensor or an oil temperature sensor for estimating the oil viscosity. These hydraulic sensors and oil temperature sensors are only mounted on a small percentage of vehicles. Therefore, if these are required by a large number of vehicles, the cost is naturally increased. In the present embodiment, the oil viscosity is estimated using a hydraulic switch mounted on most vehicles including a large percentage of vehicles. Therefore, the versatility is high and there is an advantage that an increase in cost can be suppressed.

  By the way, in this embodiment, when it is determined that there is at least one of oil deterioration abnormality and viscosity abnormality, a strong warning (strength warning) and a weak warning (in accordance with the combination of presence or absence of the deterioration abnormality and viscosity abnormality) It is also characterized by selectively issuing one of the weak warnings).

  When issuing a strong warning, the ECU 100 turns on the warning lamp 51. This forces the user to quickly replace the oil with a new standard oil. On the other hand, when issuing a weak warning, the ECU 100 displays the warning content on the multipurpose display 52. This encourages the user to change to a new standard oil at the appropriate time as soon as possible.

  Note that other warning methods are possible. For example, instead of displaying on the multi-purpose display 52 at the time of a weak warning, it is possible to turn on the service lamp or to send out a voice message.

  Next, a first example of the oil abnormality diagnosis process executed by the ECU 100 will be described with reference to FIG.

  First, in step S101, the oil viscosity μ of the currently used oil is estimated. Although the estimation is performed according to the second method here, the estimation may be performed according to the first method.

  Next, in step S102, the estimated oil viscosity μ is compared with a predetermined viscosity abnormality determination value μs. If the oil viscosity μ is larger than the viscosity abnormality determination value μs, it is determined that the oil viscosity μ of the currently used oil is too high, that is, the viscosity is high, and the process proceeds to step S103, where the viscosity abnormality determination is made.

  On the other hand, if the oil viscosity μ is equal to or lower than the viscosity abnormality determination value μs, the processing is ended assuming that the oil viscosity μ of the oil currently used is standard, that is, low viscosity.

  When the oil viscosity is estimated by the first method, if the estimated viscosity is high, the process proceeds to step S103, and if the estimated viscosity is low, the process is terminated.

  After the viscosity abnormality determination in step S103, the oil deterioration sensor 20 detects the deterioration degree X of the oil currently used in step S104. In step S105, the detected oil deterioration degree X is compared with a predetermined deterioration abnormality determination value Xs.

  If the oil deterioration degree X is larger than the deterioration abnormality determination value Xs, it is determined that the deterioration degree X of the currently used oil is too high, and the process proceeds to step S106, where deterioration abnormality determination is made. In step S107, the warning lamp 51 is turned on. This corresponds to the case where it is determined that both the viscosity abnormality and the deterioration abnormality are present and a strong warning is issued.

  On the other hand, if the oil deterioration degree X is equal to or less than the deterioration abnormality determination value Xs, the deterioration degree X of the oil currently used is within the allowable range, and the process proceeds to step S108, and only the high-viscosity display 52 is high viscosity. Is displayed. This corresponds to the case where it is determined that there is a viscosity abnormality but it is determined that there is no deterioration abnormality and a weak warning is issued.

  Next, a second example of the oil abnormality diagnosis process executed by the ECU 100 will be described with reference to FIG.

  Steps S201 and S202 are the same as steps S101 and S102. When it is determined in step S202 that the estimated oil viscosity μ is larger than the viscosity abnormality determination value μs, the process proceeds to step S203, and the viscosity abnormality determination is made. Then, the process immediately proceeds to step S204, and the warning lamp 51 is turned on. This corresponds to a case where it is determined that there is a viscosity abnormality and a strong warning is issued regardless of whether there is a deterioration abnormality.

  On the other hand, when it is determined in step S202 that the oil viscosity μ is equal to or lower than the viscosity abnormality determination value μs, the oil deterioration degree X is detected in step S205. In step S206, the detected oil deterioration degree X is compared with a predetermined deterioration abnormality determination value Xs.

  When the oil deterioration degree X is equal to or less than the deterioration abnormality determination value Xs, the process is terminated. This corresponds to the case where it is determined that there is substantially no viscosity abnormality and no deterioration abnormality.

  On the other hand, when the oil deterioration degree X is larger than the deterioration abnormality determination value Xs, the routine proceeds to step S207, where deterioration abnormality determination is made. In step S208, the multipurpose display 52 displays that oil deterioration has occurred. In this case, it is determined that there is a deterioration abnormality, but it is determined that there is no viscosity abnormality and a weak warning is issued.

  The preferred embodiments of the present invention have been described in detail above, but various other embodiments of the present invention are conceivable. For example, the use and type of the internal combustion engine are arbitrary. The installation positions of the hydraulic switch and the oil deterioration sensor are also examples, and can be changed as appropriate.

  The embodiment of the present invention is not limited to the above-described embodiment, and includes all modifications, applications, and equivalents included in the concept of the present invention defined by the claims. Therefore, the present invention should not be construed as being limited, and can be applied to any other technique belonging to the scope of the idea of the present invention.

1 Internal combustion engine 20 Hydraulic switch 30 Oil deterioration sensor 100 Electronic control unit (ECU)

Claims (7)

An apparatus for diagnosing an abnormality of an oil which is a lubricating oil of an internal combustion engine,
A deterioration level acquisition means for detecting or estimating the deterioration level of the oil;
Viscosity acquisition means for detecting or estimating the viscosity of the oil;
A determination unit that distinguishes between the deterioration degree of the oil and the presence or absence of a viscosity abnormality based on the degree of deterioration detected or estimated by the deterioration degree acquisition unit and the viscosity detected or estimated by the viscosity acquisition unit;
An oil abnormality diagnosis device comprising: Warning means for selectively issuing either a strong warning or a weak warning depending on the combination of the presence of deterioration abnormality and viscosity abnormality when it is determined by the determination means that there is at least one of deterioration abnormality and viscosity abnormality The oil abnormality diagnosis device according to claim 1, further comprising: The oil abnormality diagnosis apparatus according to claim 2, wherein the warning unit issues a strong warning when the determination unit determines that both deterioration abnormality and viscosity abnormality are present. 4. The oil abnormality diagnosis device according to claim 2, wherein the warning unit issues a weak warning when the determination unit determines that there is a viscosity abnormality but determines that there is no deterioration abnormality. 5. The oil abnormality diagnosis device according to claim 2, wherein the warning unit issues a strong warning when the determination unit determines that there is a viscosity abnormality. The oil abnormality diagnosis apparatus according to claim 2 or 5, wherein the warning means issues a weak warning when the determination means determines that there is a deterioration abnormality but determines that there is no viscosity abnormality. The viscosity acquisition means includes a hydraulic switch provided at a predetermined position of the oil circulation path, and estimates the viscosity of the oil using an output signal of the hydraulic switch. The oil abnormality diagnosis device according to one item.

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