JP4869202B2 - Blow-by gas detection method for a 4-cycle multi-cylinder engine - Google Patents

Description

  The present invention relates to a method for detecting blow-by gas pressure of a four-cycle multi-cylinder engine having a plurality of cylinders and a crankcase common to each cylinder.

  In a 4-cycle multiple cylinder engine, during engine operation, part of the gas in the combustion chamber leaks into the crankcase as blow-by gas from the gap between the piston ring and the cylinder liner. This blow-by gas is mainly a combustion gas generated during combustion (explosion) in the combustion chamber, but also includes compressed air (supply air) that leaks from the combustion chamber into the crankcase during the compression stroke.

  When the engine is used from the normal initial operating state, sliding members in the cylinder such as the piston ring and the cylinder liner wear, and when the amount of wear of the sliding members increases or is damaged, the cylinder seal Sex is greatly reduced. When the sealing performance of the cylinder is lowered, the amount of blow-by gas in the crankcase is increased, thereby hindering smooth piston operation. In addition, as the amount of accumulated combustion gas (oil mist) in the crankcase increases, the lubricating oil stored in the oil pan rapidly deteriorates. That is, the sulfur component in the combustion gas leaked from the cylinder is mixed with the lubricating oil, the alkali number of the lubricating oil is lowered, and the viscosity is increased by the residue contained in the blow-by gas, and the lubricating function is lowered. Further, the increased blow-by gas has a high temperature and contains combustion residues as described above, causing deterioration of lubricity of the sliding member and corrosion of the sliding member, and promoting wear of these sliding members. To do.

  FIG. 10 is a diagram showing the relationship between the amount of increase in blow-by gas into the crankcase and the wear amount of sliding members such as piston rings, cylinder liners, and piston ring grooves in a four-cycle engine. As the amount of wear increases, the increase in blow-by gas (the amount of leakage of combustion gas, etc.) increases. Point A1 is a wear limit point indicating the time when the sliding member needs to be replaced. When the amount of wear increases up to point A1, the sliding member needs to be replaced.

  11 and 12 are graphs showing the relationship between the degree of deterioration of the lubricating oil stored in the oil pan and the amount of increase in blow-by gas in the crankcase. The degree of deterioration of the lubricating oil shown in FIG. Specifically, it is a decrease in rare earth nitrides such as TBN, and the degree of deterioration of the lubricating oil shown in FIG. 12 is specifically an increase in the viscosity of the lubricating oil. As the amount of increase in blow-by gas increases, TBN and the like decrease and the viscosity increases, which indicates that the degree of deterioration of the lubricating oil increases. Points A2 and A3 are usage limits indicating the replacement timing of the lubricating oil, respectively. When the degree of deterioration of the lubricating oil proceeds to the point A2 or the point A3, the lubricating oil needs to be replaced.

  As one of the methods for knowing the replacement timing of the sliding member due to wear or damage of the sliding member of the cylinder as described above, there is a conventional method of actually measuring the wear amount of each sliding member, and deterioration of the lubricating oil. As one of the methods for knowing the time for replacing the lubricating oil, there is a method of analyzing the lubricating oil component based on the operating time of the engine. As another conventional method, a static change in the crankcase pressure is measured by the pressure detection means, so that the change in the blowby gas pressure in the crankcase is indirectly measured, and the blowby gas is changed from the change in the blowby gas increase pressure. Changes in the amount of gas increase are detected, and based on the detected amount of increase in blow-by gas, the degree of wear of the sliding member, the degree of deterioration of the lubricating oil, and their replacement timing are obtained from the relationships of FIGS. Like to know.

  However, in the above conventional method, the static change in the crankcase internal pressure is measured by the pressure detecting means, and the change in the overall blowby gas pressure in the crankcase is thereby measured. Although it is possible to recognize a change in the amount of increase in blow-by gas, it is not possible to recognize a change in blow-by gas pressure and a change in the amount of increase in blow-by gas for each cylinder in a multi-cylinder engine.

  On the other hand, in order to recognize the change in the blow-by gas increase pressure and the increase amount for each cylinder, it is conceivable to arrange a pressure sensor for each cylinder. In addition to the increase in cost, installation work and maintenance are also time-consuming.

(Object of invention)
An object of the present invention is to measure a change in crankcase pressure by one or a plurality of pressure sensors in a four-cycle engine having a plurality of cylinders, thereby changing the blow-by gas increase pressure for each cylinder and thereby increasing the amount of blow-by gas. It is possible to detect the change in the amount of wear and to monitor the wear state and damage of the sliding member for each cylinder.

  In order to solve the above-mentioned problem, the invention according to claim 1 is directed to a blow-by gas detection method for a four-cycle multiple cylinder engine having a plurality of cylinders and a crankcase common to each cylinder. Is continuously input to the control means, and the pressure in the crankcase is measured continuously or at least at a predetermined crank angle interval and input to the control means. It is characterized in that a change in blow-by gas pressure for each cylinder is detected based on a change in pressure in the crankcase at every crank angle interval.

  According to the above measurement method, while measuring the pressure change in the entire crankcase with one pressure sensor, the pressure change is measured for each predetermined crank angle, so that the blow-by gas increase pressure and the increase amount for each cylinder are measured. Change can be detected. That is, while suppressing the cost of parts for the pressure sensor, it is possible to monitor the change or damage of the wear amount of the sliding member for each cylinder while avoiding troublesome mounting and maintenance of the pressure sensor. To know the appropriate replacement time. It is also possible to know the replacement time of the lubricating oil due to the deterioration of the lubricating oil.

According to a second aspect of the present invention, in the blowby gas detection method according to the first aspect, a preset limit blowby gas increase pressure with respect to a crankcase pressure during normal initial operation of the engine is stored, and the control means The calculation unit compares the maximum blowby gas increase pressure near the explosion timing of each cylinder detected during normal operation after normal initial operation with the limit blowby gas increase pressure, and the detected blowby gas increase pressure is the limit blowby gas When it is determined that the pressure is larger than the increased pressure, the blow-by gas amount from the corresponding cylinder into the crankcase is recognized to be abnormally increased.

  According to the above method, (1) the maximum blowby gas increase pressure in the vicinity of the explosion timing of each cylinder is detected and compared with a preset limit blowby gas increase pressure. Compared with the method of measuring the static average value of the pressure change, it is possible to detect an abnormal increase in the amount of blow-by gas quickly and accurately. Thereby, the wear limit or damage of the sliding member can be known at an early stage, and the sliding member can be replaced at an appropriate time.

(2) Since the change in the blow-by gas pressure near the explosion timing of each cylinder is detected, it can be easily known which blow-by gas amount of each cylinder is abnormally increased, and the sliding member has a wear limit or A damaged cylinder can be easily identified. Therefore, when repairing the sliding member or exchanging parts, it is only necessary to disassemble only the specified cylinder and perform repairing or exchanging parts, and the maintenance work can be greatly omitted.

  According to a third aspect of the present invention, in the method for detecting blow-by gas of the four-cycle multi-cylinder engine according to the first or second aspect, the inside of the crankcase is sealed and the crankcase pressure is measured by the pressure detecting means. It is a feature.

  According to the above method, the change in the crankcase pressure becomes more prominent than when the crankcase pressure is measured by opening the crankcase to the atmosphere. And it can be done accurately.

  According to a fourth aspect of the present invention, in the method for detecting blowby gas of the four-cycle multiple cylinder engine according to any one of the first to third aspects, the pressure detecting means is provided from a position of a breather pipe that opens the inside of the crankcase to the atmosphere. It is characterized by detecting the pressure at a location separated by one cylinder or more.

  According to the above method, even if the change in the crankcase pressure is measured in the open air state, the pressure in the crankcase is measured at a place where the effect of the pressure relief by the breather pipe is small. A good pressure detection function can be maintained.

  1 to 9 show an embodiment of a 4-cycle 6-cylinder engine that implements a blow-by gas detection method according to the present invention and a detection method thereof.

[Entire engine structure]
FIG. 1 is a schematic vertical sectional view of a four-cycle six-cylinder engine. A cylinder block 2 is coupled to an upper end of a crankcase 1, and the cylinder block 2 includes a first cylinder 4-1 to a sixth cylinder 4-6. Six cylinders are provided, and each of the cylinders 4-1, 4-2,... 4-6 communicates with the one common crankcase 1, and each piston 7 is slidably fitted. Has been. Cylinder heads 6 are coupled to the upper ends of the respective cylinders 4-1, 4-2,. A crankshaft 10 common to each cylinder is rotatably disposed in the crankcase 1. The crankshaft 10 is connected to pistons 7 of the respective cylinders 4-1, 4-2,. The crankshaft 10 has one end projecting out of the crankcase 1 and a flywheel 11 fixed to the projecting portion. A breather pipe (oil mist pipe) 23 is provided on the opposite side of the crankcase 1 from the side where the flywheel 11 is disposed. The breather pipe 23 is provided with an opening / closing valve 24. The inside of the crankcase 1 is substantially sealed by opening the inside of the case 1 to the atmosphere and closing the opening / closing valve 24. An oil pan 3 storing lubricating oil L is coupled to the lower end of the crankcase 1. The explosion order (ignition order) of each of the cylinders 4-1, 4-2,..., 4-6 is the first cylinder 4-1, the fourth cylinder 4-4, the second cylinder 4-2, and the sixth cylinder 4-6. The third cylinder 4-3 and the fifth cylinder 4-5 are exploded at a crank angle interval of 120 °.

  FIG. 2 is a schematic enlarged cross-sectional view of the first cylinder 4-1, and for example, three annular ring grooves 14 are formed in parallel with each other at the upper part of the outer peripheral surface of the piston 7. Each ring 8 is fitted, and the outer peripheral surface of each piston ring 8 is in sliding contact with the inner peripheral surface of the cylinder liner 9. The three piston rings 8 are, in order from the top, a top ring (compressor ring), a second ring (compressor ring), and an oil ring. During the explosion in the combustion chamber 9a, a part of the combustion gas in the combustion chamber 9a passes through the gap between the cylinder liner 9 and each piston ring 8 and leaks into the crankcase 1 as blow-by gas. Accumulated in. Further, during the compression stroke, a part of the supply air (air) leaks into the crankcase 1 through the gap as blow-by gas. In addition, the same three piston rings 8 as the first cylinder 4-1 are fitted to the pistons 7 of the second cylinder 4-2 to the sixth cylinder 4-6 in FIG.

[Pressure sensor 25, optical sensor 19, control means 26 and control contents thereof]
In FIG. 1, as means for continuously detecting the pressure in the crankcase 1 at a predetermined crank interval, an end wall opposite to the flywheel 11 side of the crankcase 1, specifically, the sixth cylinder 4-6 Is provided with a pressure sensor 25 protruding into the crankcase 1. The pressure sensor 25 is electrically connected to the control means 26, and continuously detects the pressure in the crankcase 1 at a predetermined crank interval and inputs it to the control means 26. Specifically, the crankcase pressure measured continuously or preferably at intervals of a crank angle of 0.5 °, 1 ° or 6 ° can be input to the control means 26.

  As means for detecting the crank angle of the reference cylinder, for example, the crank angle corresponding to the first cylinder 4-1, a pulse disc 18 is fixed to one end portion of the crankshaft 10, and the outer peripheral end portion of the pulse disc 18 is An optical sensor 19 that passes therethrough is disposed.

  FIG. 3 is an enlarged cross-sectional view of the crank angle detection means. A large number of light passage slits (or transparent portions) 20 are formed at predetermined intervals in the circumferential direction at the outer peripheral end of the pulse disk 18. . The optical sensor 19 is formed in a U-shaped cross section, and has a light emitting portion 21 and a light receiving portion 22 facing each other, and a space between the light emitting portion 21 and the light receiving portion 22 is provided between the light emitting portion 21 and the light receiving portion 22. The outer peripheral end portion passes through. The number of slits 20 in the pulse disk 18 varies depending on the interval of the crank angle to be measured. For example, when measuring the crank angle at intervals of 0.5 °, a pulse disk 18 in which 720 slits 20 are formed at equal intervals in the circumferential direction is used, and the crank angle is set at intervals of 1 °. In the case of measurement, the pulse disk 18 in which 360 slits 20 are formed at equal intervals in the circumferential direction is used. When the crank angle is measured at intervals of 6 °, 60 slits 20 are provided. A pulse disk 18 formed at equal intervals in the circumferential direction is used. In this embodiment, a pulse disk 18 having 720 slits 20 is used, and the crank angle is measured at intervals of 0.5. The light emitted from the light emitting unit 21 is received by the light receiving unit 22 every 0.5 ° of crank angle corresponding to the passage of the slit 20 and is input from the light receiving unit 22 to the control means 26 as a pulse signal. ing.

  The control unit 26 includes a data logger and the like, and also includes a storage unit, a calculation unit, an input unit, an output unit, and the like. A monitor 27 is connected to the control unit 26, and the monitor 27 allows various detection values and The calculated value can be monitored. As described above, the input portion of the control means 26 receives the detected pressure and the detected crank angle from the pressure sensor 25 and the light sensor 19 for detecting the crank angle.

  In the storage unit of the control means 26, for example, the basic pressure change in the crankcase 1 when changing based only on the piston vertical movement and the inside of the crankcase detected by the pressure sensor 25 during normal initial operation of the engine are stored. , Initial blow-by gas pressure change substantially corresponding to the difference between the initial pressure change and the basic pressure change, and a preset limit blow-by gas increase pressure (described in detail later) are stored. ing. The calculation unit of the control means 26 compares the maximum blowby gas increase pressure near the explosion timing of each cylinder detected during normal operation after normal initial operation with the limit blowby gas increase pressure, and detects the detected blowby gas increase pressure. Is determined to be larger than the limit blow-by gas increase pressure, it is recognized that the amount of blow-by gas from the corresponding cylinder into the crankcase is abnormally increased. Hereinafter, the relationship between the increased pressure, the increased amount, and the like and the crank angle will be specifically described with reference to FIGS.

  FIG. 4 shows the change in the basic pressure B0 in the crankcase 1 due to the vertical movement of the piston, the change in the initial pressure B1 in the crankcase 1 measured in the initial operation state, and the change in the initial blowby gas pressure C1. An example of the relationship is shown, and the crank angle on the horizontal axis indicates the crank angle of the first cylinder 4-1 as described above as the reference cylinder. Since the change in piston speed due to the vertical movement of the piston becomes a sine curve, the pressure change in the crankcase 1 also follows the piston speed and becomes a substantially sine curve. In this embodiment, as shown in FIG. 1, since the pressure sensor 25 is arranged substantially directly below the sixth cylinder 4-6, the change in the basic pressure B0 in FIG. It is a sine curve that roughly corresponds to the vertical movement of the piston. The force change of the basic pressure B0 slightly varies depending on the engine speed and pressure, but always shows a constant pressure waveform when measured at the same engine speed and the same measurement position. Further, since the explosion timing of the sixth cylinder 4-6 is 360 ° with respect to the first cylinder 4-1, the change in the basic pressure B0 is such that the crank angle is 0 °, 180 °, 360 °. And it is a sine curve which becomes approximately 0 at 540 °. Of course, depending on the position of the pressure sensor 25, the waveform of the basic pressure B0 is different from that shown in FIG. For example, if the pressure sensor 25 is arranged near the second cylinder 4-2, the change in the basic pressure becomes a waveform having a phase delayed by 240 ° from the curve B0 in FIG.

  In FIG. 4, as described above, the difference between the initial pressure B1 in the crankcase 1 and the basic pressure B0 becomes the initial blow-by gas pressure C1 indicated by the dotted line. , 4-4, 4-2, 4-6, 4-3, 4-5, respectively, at the top dead centers TDC1, TDC4, TDC2, TDC6, TDC3, and TDC5 in the vicinity of the explosion timing. This change in the initial blow-by gas pressure C1 is also stored in the storage unit as a reference value for detecting the blow-by gas increase pressure during operation.

  FIG. 5 is a diagram illustrating an example of a change in blow-by gas increase pressure during normal operation as a graph D1. Since the change in the initial blow-by gas pressure C1 in FIG. 4 serves as a reference for the increase in blow-by gas pressure, the initial blow-by gas pressure C1 in FIG. 5 is represented by a straight line as shown by a one-dot chain line. Further, a broken line graph B2 represents the pressure in the crankcase detected by the pressure sensor 26 when the blow-by gas pressure is increased in the normal operation. That is, the difference between the crankcase pressure B2 detected during normal operation and the normal crankcase pressure B1 during normal operation is described as the blow-by gas increase pressure D1 during normal operation.

  FIG. 6 is a graph showing only the change in blow-by gas increase pressure D1 in FIG. 5, and the blow-by gas increase pressure D1 is shown in each cylinder 4-1, 4-4, 4-2, 4-6, 4- 3, 4-5, top dead centers TDC1, TDC4, TDC2, TDC6, TDC3, and TDC5, the explosion time increases rapidly. Further, the blow-by gas increase pressure D1 of each cylinder 4-1, 4-4, 4-2, 4-6, 4-3, 4-5 differs depending on the cylinder. A graph E0 in FIG. 6 shows an average value of the increased blowby gas pressure in the entire crankcase 1.

  FIG. 7 is a graph showing the relationship between the average value E0 of the blowby gas increase pressure in the whole crankcase obtained in FIG. 6 and the increase amount of the blowby gas accumulated in the crankcase. The increase amount of the value E0 is substantially proportional to the increase amount of blow-by gas. From the relationship shown in FIG. 7, the amount of blow-by gas increase can be easily estimated from the blow-by gas increase pressure in the crankcase.

  FIG. 8 is a diagram showing a change in blow-by gas increase pressure when the amount of blow-by gas from one cylinder abnormally increases. When the blow-by gas amounts of all the cylinders are normally increased, the blow-by gas increase pressure of each cylinder is increased on average as shown by the broken line graph D2, for example, the second cylinder 4 When the amount of blow-by gas from -2 increases abnormally compared to the other cylinders, the maximum blow-by gas increase pressure near the explosion timing of the second cylinder (near TDC2) becomes the maximum of other cylinders as shown by graph D2 '. It becomes abnormally larger than the blow-by gas increase pressure. In order to detect this automatically, the above-mentioned limit blowby gas increase pressure P1 is set in advance and stored in the storage unit of the control means 26. When this limit blowby gas increase pressure P1 is exceeded, the second cylinder It can be recognized on the monitor 27 that the amount of blowby gas is abnormally increased. In addition to being recognized by the monitor 27, a program for the control means 26 can be incorporated so that an appropriate alarm device is activated to automatically stop the engine.

  FIG. 9 is a graph of blow-by gas increase pressure when detecting the part replacement time of the sliding member of each cylinder. The explosion times of the cylinders 4-1, 4-4, 4-2, 4-6, 4-3, 4-5 are arranged at approximately 120 ° intervals in the crank angle according to this order. 4-1, 4-4, 4-2, 4-6, 4-3, 4-5, each of the top dead centers TDC1, TDC4, TDC2, TDC6, TDC3, and TDC5 are separated from each other in the range of 60 °, respectively. Within the range of 120 ° corresponding to the cylinder, average blow-by gas increase pressure values E1, E4, E2, E6, E3, E5 in each section (120 ° section) are calculated. For example, the blowby gas increase pressure average value E1 of the first cylinder 4-1 is an average value of the blowby gas increase pressure in the range of the crank angle from −60 ° to 60 °, and the blowby gas increase of the fourth cylinder 4-4. The average pressure value E4 is an average value of the blow-by gas increase pressure in the range of the crank angle from 60 ° to 180 °, and the blow-by gas increase pressure average value E2 of the second cylinder 4-2 is the crank angle from 180 ° to 300 °. The average value of the blowby gas increase pressure in the range of 6 °, and the average value E6 of the blowby gas increase in the sixth cylinder 4-6 is the average value of the blowby gas increase pressure in the range of the crank angle from 300 ° to 420 °. The blowby gas increase pressure average value E3 of the third cylinder 4-3 is the average value of the blowby gas increase pressure in the range of the crank angle from 420 ° to 540 °, and the blowby gas increase pressure of the fifth cylinder 4-5 Scan increased pressure average value E5 is the average value of the blow-by gas increases pressure in the range of 660 ° crank angle 540 ° (-60 °). On the other hand, a straight line E10 indicated by a thick broken line indicates the relationship between the amount of increase in blow-by gas in FIG. 10 and the amount of wear of the engine sliding member, the amount of increase in blow-by gas in the crankcase in FIG. This is the required blowby gas increase pressure corresponding to the limit wear amount obtained from the relationship with the average value E0 of the pressure. That is, when any one of the blowby gas increase pressure average values E1, E4, E2, E6, E3, and E5 in FIG. 9 exceeds the replacement required blowby gas increase pressure E10, the corresponding cylinder sliding member It is possible to recognize that it is time for replacement. Incidentally, in the case of FIG. 9, the blow-by gas increased pressure average value E2 of the second cylinder exceeds the replacement required blow-by gas increased pressure E10, so that the sliding member of the second cylinder has reached the replacement time. Is shown.

[Measurement and pressure work]
Since the control by the control means and the monitoring by the monitor are generally explained in the explanation section of the control means, the actual measurement work, the monitoring work, etc. will be briefly explained here in time series.

(Monitoring the increase in blow-by gas pressure and the amount of increase)
(1) In a normal initial operation state in which all the normal members are used as the sliding members for all the cylinders, as shown in FIG. 4, the pressure in the crankcase 1 measured by the pressure sensor 25 is a graph B1. Therefore, the pressure of the blow-by gas in the crankcase 1 also changes as shown in the graph C1.

(2) When detecting the amount of blow-by gas in the crankcase 1 during normal operation after a certain period of time after normal initial operation, first, in order to maintain high measurement accuracy, the breather tube 23 of FIG. The on-off valve 24 is closed and the crankcase 1 is sealed. In this sealed state, the pressure sensor 25 continuously measures the entire pressure change in the crankcase 1 and inputs it to the control means 26, and the optical sensor 19 detects the reference cylinder, that is, the first cylinder 4-1. The crank angle is continuously detected, and the change in the crank angle is input to the control means 26.

(3) In the normal operation described above, sliding members such as piston rings used in each cylinder are worn by each cylinder, and the blow-by gas pressure and amount increase according to the wear amount for each cylinder. As shown in FIG. 5, the increase pressure and the increase amount of the blowby gas are the total pressure B2 in the crankcase 1 detected by the pressure sensor 25, the initial pressure B1, and the crank angle detected by the optical sensor 19. Based on this, it is obtained for each cylinder by the control means 26, and by monitoring them with the monitor 27, it is possible to monitor the change in the blow-by gas increase pressure and the change in the increase amount for each cylinder as shown in FIG.

  That is, as described with reference to FIG. 5, the difference between the pressure B2 input from the pressure sensor 25 during the normal operation and the initial pressure B1 stored in advance in the storage unit is calculated, and the blowby with respect to the initial blowby gas pressure C1 is calculated. The increase pressure D1 of the gas is obtained, and as shown in FIG. 6, the blowby gas increase pressure D1 and the increase amount of the blowby gas estimated from the increase pressure D1 are output to the monitor 27 and monitored.

  In FIG. 6, the blow-by gas increase pressure D1 varies depending on each cylinder, but the blow-by gas increase pressure D1 at the explosion timing (near TDC 0 °, 120 °, 240 °, 360 °, 480 °, and 600 °) of each cylinder is shown. By monitoring, it is possible to accurately recognize changes in the blow-by gas increase pressure and increase amount for each cylinder.

(Detection of abnormal increase in blow-by gas pressure and increase)
In the state where the blow-by gas increase pressure and the increase amount are monitored, for example, when the sliding member of the second cylinder is damaged and the sealing performance of the second cylinder is impaired, as shown in FIG. The maximum blow-by gas increase pressure (and the maximum increase amount) D2 ′ in the vicinity of the explosion timing of the second cylinder (near TDC2) becomes abnormally larger than the maximum blow-by gas increase pressure of the other cylinders, and becomes a predetermined limit blow-by gas increase pressure. When P1 is exceeded, it can be determined that the blow-by gas amount of the second cylinder has increased abnormally. That is, it can be recognized that the sliding member of the second cylinder is damaged or the amount of wear suddenly increases. In this case, it can be recognized by monitoring the monitor 27, but in addition to monitoring, control such as warning and engine stop can be automatically performed.

(Detection of replacement timing of sliding member for each cylinder)
As already described with reference to FIG. 8, as the part replacement index of the sliding member, it is necessary to replace the sliding member of the corresponding cylinder when an abnormality is detected from the maximum blowby gas increase pressure or increase amount for each cylinder. In addition, as described with reference to FIG. 9, the blowby gas increase pressure average values E1, E4, E2, E6, E3, and E5 are calculated for each cylinder, and these blowby gas increase pressure averages are calculated. A value E1, E4, E2, E6, E3, E5 is compared with the required blowby gas increase pressure E10, and the cylinder that exceeds the required blowby gas increase pressure E10, that is, the second cylinder 4-2. It can be recognized that it is time to replace the sliding member.

(Detection of lubricating oil replacement time)
It is not necessary to determine the change in the blowby gas increase pressure or the amount of blowby gas for each cylinder at the time of replacement of the lubricating oil, the average value E0 of the blowby gas increase pressure in the entire crankcase described with reference to FIG. From the relationship between the deterioration of the lubricating oil and the amount of blow-by gas increase (blow-by gas increase pressure) described in FIG. 12, the average value E0 of the blow-by gas increase pressure in the entire crankcase is the use limit point of each lubricant in FIG. When the value rises to a value corresponding to the amount of increase in blow-by gas of A2 and A3, it can be recognized that it is time to change the lubricant.

[Other embodiments]
(1) The pressure measurement in the above embodiment is performed with the opening / closing valve 24 of the breather pipe 23 closed in FIG. 1, but the measurement may be performed with the opening / closing valve 24 of the breather pipe 23 opened. Is possible.

(2) As indicated by phantom lines in FIG. 1, the pressure sensor 25 ′ may be disposed on the end wall on the opposite side of the breather tube 23 in the crankcase 1. According to this embodiment, even when the pressure in the crankcase is measured with the open / close valve 24 open and opened to the atmosphere, the subtle pressure change is more accurate than when the pressure sensor 25 is arranged on the breather pipe 23 side. It can be measured well. In the case of measuring in an open air state, if the pressure sensor 25 is disposed at a location separated from the breather tube 23 by one cylinder or more, the crankcase pressure change can be measured with high accuracy.

(3) Although the above embodiment is an example applied to a 6-cylinder engine, it can also be applied to a 2-cycle to 5-cylinder 4-cycle engine or a 4-cycle engine having 7 or more cylinders.

(4) The crank angle detection means is not limited to means by a combination of the pulse disk 18 having a large number of slits 20 and the optical sensor 19 as shown in FIGS. 1 and 3, and the transmission connected to the engine. Various detection means such as a means for detecting the crank angle by detecting the rotation angle of the input shaft can be considered.

1 is a schematic cross-sectional view of a 4-cycle 6-cylinder engine that implements a blow-by gas detection method according to the present invention. FIG. 2 is a schematic enlarged cross-sectional view of a first cylinder of the engine of FIG. 1. It is a cross-sectional enlarged view of the crank angle detection means of the engine of FIG. It is a figure which shows the relationship between the change of the basic pressure in a crankcase by the piston vertical movement etc. in a normal initial driving | running state, the detected change of the initial pressure in a crankcase, and the change of the initial pressure of a blow-byger. It is a figure which shows the relationship between the change of the pressure in a crankcase detected at the time of normal driving | operation, the change of the initial pressure in a crankcase, and the change of the increase pressure of blow blower. It is a figure which shows the change of the blow-by gas increase pressure detected at the time of normal operation, and its average value. It is a figure which shows the relationship between the blowby gas increase pressure average value in the whole crankcase, and the amount of blowby gas increase in a crankcase. It is a figure which shows the relationship between the blow-by gas increase pressure and crank angle when the amount of blow-by gas from one cylinder increases abnormally. It is a figure which shows the relationship between the blow-by gas increase pressure at the time of detecting the components replacement | exchange time of the sliding member of one cylinder, and a crank angle. It is a figure which shows the relationship between the increase amount of blow-by gas in a crankcase, and the abrasion loss of sliding members, such as a piston ring, a cylinder liner, and a piston ring groove | channel. It is a figure which shows the relationship between the degree of total basification based on deterioration of the lubricating oil stored in the oil pan, and the amount of blow-by gas in a crankcase. It is a figure which shows the relationship between the deterioration degree based on deterioration of the lubricating oil stored by the oil pan, and the amount of blow-by gas in a crankcase.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Crankcase 2 Cylinder head 3 Oil pan 4-1, 2, 3, 4, 5, 6 1st, 2nd, 3rd, 4th, 5th and 6th cylinder 7 Piston (sliding member)
8 Piston ring (sliding member)
18, 19 Pulse disk, optical sensor (an example of crank angle detection means)
25, 25 'Pressure sensor (pressure detection means)
26 Control means 27 Monitor

Claims (4)

In a blow-by gas detection method for a four-cycle multi-cylinder engine having a plurality of cylinders and a crankcase common to each cylinder,
The crank angle detection means continuously detects the crank angle and inputs it to the control means,
The pressure detection means measures the crankcase pressure continuously or at least at a predetermined crank angle interval and inputs it to the control means,
4. A blow-by gas detection method for a 4-cycle multi-cylinder engine, wherein the control means detects a change in blow-by gas pressure for each cylinder based on a change in pressure in the crankcase at each predetermined crank angle interval. The storage unit of the control unit stores a preset limit blowby gas increase pressure with respect to the pressure in the crankcase during normal initial operation of the engine, and the calculation unit of the control unit performs normal operation after normal initial operation. When the maximum blow-by gas increase pressure near the explosion timing of each cylinder detected during operation is compared with the limit blow-by gas increase pressure, and it is determined that the detected blow-by gas increase pressure is greater than the limit blow-by gas increase pressure 2. The blow-by gas detection method for a 4-cycle multiple cylinder engine according to claim 1, wherein the blow-by gas amount from the cylinder to the crankcase is recognized to be abnormally increased.   The blow-by gas detection method for a 4-cycle multi-cylinder engine according to claim 1 or 2, wherein the crankcase pressure is measured by the pressure detection means while the crankcase is sealed.   The four-cycle multiple cylinder according to any one of claims 1 to 3, wherein the pressure detecting means detects a pressure at a location one cylinder or more away from a position of a breather pipe that opens the inside of the crankcase to the atmosphere. Engine blow-by gas detection method.

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