JP4633186B1 - Oil mist concentration detector - Google Patents

Abstract

[PROBLEMS] To accurately detect the oil mist concentration in each crank chamber without reducing the responsiveness even if the number of detection points of the oil mist concentration is reduced from the number of crank chambers in order to reduce the installation work and maintenance work of the device. To do.
Oil mist sensors are attached to three crank chambers 61, 63, and 65 among crank chambers 61 to 65 of a five-cylinder engine 70. The control unit 50 determines the mist concentration in the crank chambers 61, 63, 65 based on the sensor output. On the other hand, the mist concentrations in the crank chambers 62 and 64 are determined based on the mist concentrations in the adjacent crank chambers. Specifically, when the mist concentration in the crank chamber 61 and 63 is the threshold value P ₁₁ or more, the mist concentration in the crank chamber 62 is determined to be the threshold value P ₁₂ or more.
[Selection] Figure 6

Description

  The present invention relates to an oil mist concentration detection device that detects an oil mist concentration in a crankcase having three or more crank chambers for each crank chamber.

  In an internal combustion engine such as a diesel engine, lubricating oil may be heated due to overheating of the crankshaft bearing, and oil mist may be generated in the crankcase. Conventionally, oil mist concentration detection devices described in Patent Literature 1 and Patent Literature 2 are known as devices for detecting the oil mist concentration in a crankcase of an internal combustion engine.

  The conventional oil mist concentration detection device constantly monitors the oil mist concentration in the crankcase with an oil mist sensor, and outputs an alarm indicating an abnormal concentration when the oil mist concentration exceeds a predetermined value. The user can know the abnormal state of the oil mist concentration in the crankcase by this alarm. Thereby, the user can prevent a failure of the internal combustion engine and a serious accident of the internal combustion engine.

JP 2005-164408 A JP 2005-106017 A

  In general, a crankcase of an internal combustion engine is provided with a plurality of crank chambers corresponding to each cylinder, and each crank chamber is partitioned by a partition wall for each cylinder. Therefore, when the conventional oil mist concentration detection device is applied to a multi-cylinder internal combustion engine, the oil mist sensor detects each oil mist concentration in each of the plurality of crank chambers corresponding to each cylinder. Attached to. In this case, since the same number of oil mist sensors as the number of cylinders is necessary, the larger the number of cylinders, the more complicated the operation of installing the oil mist concentration detection device and the maintenance work for one internal combustion engine. On the other hand, if the number of oil mist sensors is reduced with respect to the number of crank chambers to reduce the number of detection points, the complexity of the installation work and maintenance work of the oil mist concentration detection device is reduced. However, since the oil mist concentration in the crank chamber to which the oil mist sensor is not attached cannot be detected, it is not possible to detect a concentration abnormality in the crank chamber.

  By the way, the partition provided between the crank chambers does not completely separate adjacent crank chambers. In other words, the partition wall is provided with a gap connecting adjacent crank chambers. Therefore, the lubricating oil stored in the bottom of the crankcase, the gas in the crankcase, and the like can be distributed to the adjacent crank chamber through the gap. In the case of a crankcase provided with a partition wall having such a gap, when a large amount of oil mist is generated in a crank chamber where an abnormality such as bearing overheating has occurred, the oil mist gradually enters the adjacent crank chamber through the gap. The oil mist concentration in the adjacent crank chamber also increases. Therefore, even if the oil mist sensors are not attached to all the crank chambers, it is possible to detect an abnormality in the concentration of oil mist if at least one oil mist sensor is attached. However, when an abnormality such as bearing overheating occurs in a crank chamber to which no oil mist sensor is attached, there is a problem that the response from the occurrence of abnormality to the detection of concentration abnormality is extremely poor. There is also a problem that the crank chamber in which an abnormality has occurred cannot be specified.

  Therefore, the present invention has been made in view of the above circumstances, and its purpose is to reduce the oil mist concentration detection point from the number of crank chambers in order to reduce the installation work and maintenance work of the device, An object of the present invention is to provide an oil mist concentration detecting device capable of accurately detecting the oil mist concentration for each crank chamber without deteriorating responsiveness.

(1) According to the present invention, the oil mist concentration in the crankcase having at least the first crank chamber, the second crank chamber, and the third crank chamber provided between the first crank chamber and the second crank chamber is determined for each crank chamber. It is configured as an oil mist concentration detecting device for detecting the oil mist. The oil mist concentration detection device includes a first sensor, a second sensor, and a control device. The first sensor outputs a signal representing the oil mist concentration in the first crank chamber. The second sensor outputs a signal representing the oil mist concentration in the second crank chamber. The control device includes a determination unit that determines an oil mist concentration in the third crank chamber based on two output signals output from the first sensor and the second sensor.

  When bearing overheating or the like occurs in the third crank chamber and oil mist is generated, the oil mist concentration in the third crank chamber rises at a stretch. As time passes, the oil mist in the third crank chamber gradually moves to the first crank chamber and the second crank chamber, and the oil mist concentrations in both the first crank chamber and the second crank chamber are approximately the same at the same speed. It will gradually rise. That is, when oil mist is generated in the third crank chamber, which is the source of the abnormality, a phenomenon occurs in which the oil mist concentrations in both the first crank chamber and the second crank chamber increase substantially simultaneously. This is a close relationship between the increase in the oil mist concentration in the third crank chamber, which is the source of the abnormality, and the increase in the oil mist concentration in both the first crank chamber and the second crank chamber at the same time. Means that. The oil mist concentration detection device of the present invention was made paying attention to such a relationship. According to the oil mist concentration detection device, two outputs output from the first sensor and the second sensor, respectively. Based on the signal, the oil mist concentration in the third crank chamber is determined. Therefore, the oil mist concentration in the first crank chamber and the second crank chamber to which the sensor is attached is detected accurately, and the oil mist concentration in the third crank chamber to which the sensor is not attached is also detected by the control device. The determination unit makes an accurate and quick determination.

(2) The determination unit outputs a first output signal representing the first concentration or more and less than the second concentration as the oil mist concentration in the crank chamber corresponding to each sensor from each of the first sensor and the second sensor. As a result, the oil mist concentration in the third crank chamber is determined to be equal to or higher than the second concentration.

  For example, it is assumed that bearing mist is generated in the third crank chamber and oil mist is generated. In this case, first, the oil mist concentration in the third crank chamber rises to the second concentration or more, and the oil mist concentration in both the first crank chamber and the second crank chamber gradually rises at the same speed. In this case, the oil mist concentration in the first crank chamber and the second crank chamber, which rises with a delay, is lower than the oil mist concentration in the third crank chamber (for example, not less than the first concentration and less than the second concentration). Under such an environment, the determination unit determines the oil mist concentration in the third crank chamber when the oil mist concentration in both the first crank chamber and the second crank chamber is not less than the first concentration and less than the second concentration. It is determined that the second concentration or higher.

  When oil mist is generated due to bearing overheating in the first crank chamber, the oil mist concentration in the first crank chamber first rises to the second concentration or higher, and later, the oil mist concentration in the third crank chamber is increased. Rises, and the oil mist concentration in the second crank chamber rises later. In this case, the control device determines that the oil mist concentration in the first crank chamber is equal to or higher than the second concentration as usual.

(3) The control unit has an alarm output unit. The alarm output unit is configured to output the first crank chamber and the second sensor on condition that a second output signal indicating the second concentration or more is output from either or both of the first sensor and the second sensor. Warning that the concentration abnormality in both or one of the two crank chambers is output, and the determination unit determines that the oil mist concentration in the third crank chamber is equal to or higher than the second concentration. An alarm indicating a concentration abnormality in the third crank chamber is output.

  Since it is configured in this way, it is possible to accurately notify the occurrence of a concentration abnormality and the location of occurrence thereof regardless of whether or not a sensor is attached to the crank chamber.

(4) The first concentration is based on measured data of output signals output from the first sensor and the second sensor when oil mist having the second concentration or more is generated in the third crank chamber. This is the concentration value to be determined.

  Since the first concentration is thus determined, the concentration abnormality in the third crank chamber is accurately determined.

  According to the oil mist concentration detection device of the present invention, even if the number of detection points of the oil mist concentration is smaller than the number of crank chambers, the oil mist concentration for each crank chamber can be accurately detected without deteriorating responsiveness. it can. For this reason, the installation work and maintenance work of the oil mist concentration detection device are reduced.

FIG. 1 is a schematic diagram showing a schematic configuration of an oil mist concentration detection apparatus 10 according to an embodiment of the present invention. FIG. 2 is a schematic side view showing the configuration of the oil mist sensors 21, 22, 23 provided in the oil mist concentration detection device 10. FIG. 3 is a front view of the controller 40 provided in the oil mist concentration detection device 10. FIG. 4 is a block diagram illustrating the configuration of the control unit 50 of the controller 40 and the signal transmitting / receiving unit 27 of the oil mist sensors 21, 22, and 23. FIG. 5 is a graph showing changes in the oil mist concentration when an oil mist having a predetermined concentration is artificially generated in the crank chamber corresponding to the third cylinder of the 5-cylinder engine. FIG. 6 is a flowchart illustrating a procedure of density abnormality determination processing executed by the control unit 50.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings as appropriate. The embodiment described below is merely an example in which the present invention is embodied, and the present embodiment may be modified without changing the gist of the present invention.

  FIG. 1 is a schematic diagram showing a schematic configuration of an oil mist concentration detection apparatus 10 according to an embodiment of the present invention. As shown in FIG. 1, the oil mist concentration detection device 10 of the present embodiment is applied to an inline engine 70 having five cylinders. Inside the crankcase 73 of the engine 70, five crank chambers 61 to 65 corresponding to each cylinder are defined. A wall 74 is provided between the crank chamber and the crank chamber. However, the wall 74 does not completely separate adjacent crank chambers. That is, the crank chambers 61 to 65 are connected so that the lubricating oil stored in the bottom of the crankcase 73, the gas in the crankcase 73, and the like can go to and from each other. Specifically, as shown in FIG. 1, a gap is provided between the lower end of the wall 74 and the bottom surface of the crankcase 73, so that lubricating oil, gas, etc. move through the crank chambers 61 to 65. it can. Since such a gap is provided in the wall 74, when a large amount of oil mist is generated in any of the crank chambers, the oil mist can move to the adjacent crank chamber through the gap. Of the crank chambers 61 to 65, the crank chambers 61 and 63 (or the crank chambers 63 and 65) correspond to the first crank chamber and the second crank chamber of the present invention, and the crank chamber 62 (or the crank chamber 64). This corresponds to the third crank chamber of the present invention.

  The oil mist concentration detection device 10 includes oil mist sensors 21, 22, and 23 and a controller 40, which are connected to each other via a communication cable 71 so as to communicate with each other. The oil mist sensor 21 is for detecting the oil mist concentration in the crank chamber 61 corresponding to the first cylinder, and is attached to the outer wall of the crank chamber 61. The oil mist sensor 22 is for detecting the oil mist concentration in the crank chamber 63 corresponding to the third cylinder, and is attached to the outer wall of the crank chamber 63. The oil mist sensor 23 is for detecting the oil mist concentration in the crank chamber 65 corresponding to the fifth cylinder, and is attached to the outer wall of the crank chamber 65. The oil mist sensor 21 and the oil mist sensor 22 are connected by a communication cable 71, and the oil mist sensor 22 and the oil mist sensor 23 are connected by a communication cable 71. The oil mist sensor 23 and the controller 40 are connected by a communication cable 71. Of the oil mist sensors 21, 22, and 23, the oil mist sensors 21 and 22 (or the oil mist sensors 22 and 23) correspond to the first sensor and the second sensor of the present invention.

  FIG. 2 is a schematic side view showing the configuration of the oil mist sensors 21, 22, and 23. The configurations of the oil mist sensors 21, 22, 23 are the same. Therefore, in the present specification, the configuration of the oil mist sensor 21 will be described in detail, and the components of the other oil mist sensors 22 and 23 will be denoted by the same reference numerals as those assigned to the components of the oil mist sensor 21. The detailed description is omitted by attaching to the drawings.

  As shown in FIG. 2, the oil mist sensor 21 includes an insertion portion 24 that is inserted into the crank chamber 61, a screw portion 25 that is screwed onto the outer wall of the crank chamber 61, and a signal transmission / reception portion 27. Yes. The screw portion 25 is formed so as to be screwable with a screw hole formed in the outer wall of the crank chamber 61. By screwing the screw portion 25 into the screw hole, the oil mist sensor 21 is attached to the outer wall of the crank chamber 61 in a state where the insertion portion 24 is disposed in the internal space of the crank chamber 61.

  The insertion portion 24 is formed in a hollow cylindrical shape. Inside the insertion unit 24, a density detection unit 34 (see FIG. 4) having a light emitting element 28 and a light receiving element 29 is provided. A round hole 26 is provided on the outer peripheral surface of the insertion portion 24. When the insertion portion 24 is disposed in the internal space of the crank chamber 61, the oil mist generated in the crank chamber 61 enters the insertion portion 24 through the round hole 20 while naturally diffusing. When the oil mist reaches the detection region of the concentration detector 34, the electrical signal output from the light receiving element 29 varies. Specifically, the electric signal output from the light receiving element 29 varies according to the oil mist concentration. In other words, the light receiving element 29 outputs an electrical signal corresponding to the concentration of oil mist present in the detection region.

  In the present embodiment, the concentration detection unit 34 is exemplified as the one that optically detects the oil mist concentration by the light emitting element 28 and the light receiving element 29, but may output a signal corresponding to the oil mist concentration. For example, the density detector 34 may have any configuration. For example, the concentration detector 34 may electromagnetically detect the oil mist concentration.

  As shown in FIG. 4, the signal transmission / reception unit 27 includes an A / D conversion unit 31, a RAM 32, and a communication unit 33. The A / D converter 31 converts an analog signal output from the light receiving element 29 into a digital signal. The digital signal generated by the A / D converter 31 is temporarily stored in the RAM 32 as digital data having a predetermined data length. This digital data is data representing the oil mist concentration in the crank chamber 61. The communication unit 33 transmits digital data in the RAM 32 to the controller 40 in response to a request from the controller 40.

  FIG. 3 is a front view of the controller 40. As shown in FIG. 3, the front panel of the controller 40 has an indicator 43 for displaying the oil mist concentration, a first warning lamp 44 for displaying a LOW level abnormality, and a second alarm for displaying a HIGH level abnormality. A lamp 45, a third warning lamp 46 that displays a system error, an operation lamp 47 that displays a normal operation state, an operation unit 48 of the controller 40, and the like are appropriately arranged.

  The indicator 43 is a plurality of LEDs arranged in the vertical direction. In the present embodiment, the controller 40 can select a crank chamber for which the oil mist concentration is to be displayed by operating the operation unit 48. The indicator 43 displays the oil mist concentration in the selected crank chamber. Specifically, the LEDs of the indicator 43 are turned on by the number corresponding to the oil mist concentration. For example, if the oil mist concentration is the lowest reference value, only the bottom LED is lit, and the upper LED is lit as the oil mist concentration is increased. The lighting control is executed by a control unit 50 (an example of a control device of the present invention) described later based on digital data transmitted from the oil mist sensors 21, 22, 23 to the controller 40.

  Note that the control unit 50 also performs lighting control of the first warning light 44, the second warning light 45, the third warning light 46, and the operation light 47. In the present embodiment, the operation lamp 47 is turned on when the oil mist concentration detection device 10 is operating normally. Further, when digital data is transmitted from the oil mist sensors 21, 22, 23 to the controller 40, a concentration abnormality determination process is performed by the control unit 50 described later, and the oil mist is detected for each of the crank chambers 61 to 65 corresponding to each cylinder. It is determined whether the concentration is abnormal. And when it determines with it being abnormal, the 2nd warning lamp 45 is lighted. Further, when a system error occurs in the oil mist concentration detection device 10, the third warning lamp 46 is displayed. Moreover, although it is not a density | concentration abnormality, when the oil mist density | concentration is a little higher than a normal value, the 1st warning lamp 44 is lighted.

  As shown in FIG. 4, a controller 50 is provided inside the controller 40. The control unit 50 executes density abnormality determination processing (see FIG. 6) described later. As shown in FIG. 4, the control unit 50 includes a calculation unit 51 such as a CPU, a program storage unit 54 such as a ROM, a data storage unit 52 such as a RAM and an EEPROM, and oil mist sensors 21, 22, and 23. A communication unit 53 that enables data communication with the communication unit 53.

The program storage unit 54 stores a program for the calculation unit 51 to execute processing necessary for controlling the oil mist concentration detection apparatus 10. The calculation unit 51 executes predetermined processing such as concentration abnormality determination processing described later according to the program. The data storage unit 52 is used as a storage area for storing various data used when the calculation unit 51 executes the concentration abnormality determination process, or as a work area for data processing. The data storage unit 52 is, for example, threshold P ₁₁ and the threshold P ₁₂ to be compared with the actually measured oil mist concentration at the time of abnormality determination is stored.

The threshold P ₁₂ is a threshold value serving as a reference for determining whether the oil mist concentration in the crank chamber is abnormal. That is, when the oil mist concentration in the crank chamber exceeds the threshold P _12, it is determined that an abnormal density. When it is determined that the concentration is abnormal, it is considered that abnormality (bearing overheating, seizure, etc.) has occurred in the oil mist generation source (for example, the bearing portion of the crankshaft) in the corresponding crank chamber. The threshold _{P 12} corresponds to a second concentration of the present invention.

The threshold P _11, the oil mist of the threshold P ₁₂ concentrations above a predetermined crank chamber (e.g. the crank chamber 63) when generated in its crankcase crankcase on both sides (e.g., the crank chamber 62 and the crank chamber 64 ) Is a threshold value determined based on actually measured data of the oil mist concentration detected in (1). Specifically, the threshold value P ₁₁ is determined in the following manner. The threshold _{P 11} corresponds to the first concentration of the present invention.

First, allowed to place the oil mist sensor in advance all of the crank chamber 61 to 65, and, artificial oil mist threshold P ₁₂ or more concentrations to the crank chamber 63 corresponding to the third cylinder of the five-cylinder engine 70 To generate. At this time, the oil mist concentration in each of the crank chambers 61 to 65 changes as shown in the graph of FIG. Incidentally, FIG. 5 is a graph showing changes in the oil mist concentration at the time of artificially generating an oil mist of a predetermined concentration (threshold P ₁₂ or more concentrations) to the crank chamber 63 corresponding to the third cylinder of the engine 70 It is. In FIG. 5, A <b> 1 indicates a change in the oil mist concentration in the crank chamber 61, and A <b> 2 indicates a change in the oil mist concentration in the crank chamber 62. A3, A4, and A5 indicate changes in the oil mist concentration in the crank chambers 63, 64, and 65, respectively.

As shown in FIG. 5, immediately after the oil mist is generated in the crank chamber 63, the oil mist concentration in the crank chamber 63 rises at once and reaches a peak value. Then, as the oil mist in the crank chamber 63 gradually moves to the adjacent crank chambers 62 and 64 with the passage of time, the oil mist concentrations in both the crank chamber 62 and the crank chamber 64 gradually increase and reach a peak value. ing. When a further time elapses, the oil mist in the crank chambers 62 and 64 gradually moves further to the adjacent crank chambers 61 and 65, whereby the oil mist concentrations in both the crank chamber 61 and the crank chamber 65 gradually increase. To do. As apparent from the graph of FIG. 5, the peak value of the oil mist concentration is highest in the crank chamber 63 that is the source of oil mist (see graph A3), and the peak value decreases as the distance from the crank chamber 63 increases. It has become. Further, in the crank chamber 62 and the crank chamber 64 adjacent to the crank chamber 63, the oil mist concentration changes substantially in the same manner, and the peak value thereof is substantially the same. That is, if the oil mist threshold P ₁₂ or more concentrations to the crank chamber 63 is generated, each crank chamber 62 and the crank chamber 64 of the both sides, that the oil mist low predetermined concentration than the threshold value P ₁₂ is present Understandable. Conversely, if the oil mist of the predetermined concentration in the crank chamber 62 and the crank chamber 64 is present, the crank chamber 63 disposed between the crank chamber 62 and the crank chamber 64, the threshold value P ₁₂ or more The oil mist of the concentration of is generated.

In this embodiment, by paying attention to the relationship between the oil mist concentration in each crank chamber of the crank chamber and both sides of the oil mist source, oil mist threshold P ₁₂ or more concentration occurs in the crank chamber of the oil mist source It is a threshold P ₁₁ the oil mist concentration in the crankcase on both sides that can be presumed. The threshold P ₁₁ defined as are used in common for engine of the same type. A plurality of threshold values P ₁₁ and P ₁₂ are stored in advance in the data storage unit 52 according to various engines having different types and cylinder diameters, and the user operates the operation unit 48 to detect the oil mist concentration. It can be set a threshold _{P 11} and the threshold _{P 12} corresponding to the engine unit 10 is applied.

  Hereinafter, the procedure of the concentration abnormality determination process executed by the control unit 50 will be described with reference to the flowchart shown in FIG. S11, S12,... In FIG. The concentration abnormality determination process starts from step S11 in FIG. In addition, when the control part 50 performs the following density | concentration abnormality determination processing, the said control part 50 functions as a determination part and an alarm output part of this invention.

  First, the control unit 50 receives digital data transmitted from the oil mist sensors 21, 22, and 23 (S11). Here, when digital data is received from all the oil mist sensors 21, 22, and 23, the received data is stored in the data storage unit 52, and then the processing after the next step S 12 is executed.

In step S12, whether the density value N1 represented by the digital data from the oil mist sensor 21 is the threshold value P ₁₂ or more is determined. Here, if it is determined that the density value N1 is the threshold value P ₁₂ or more, the determination result, high oil mist concentration in the crank chamber 61, the crank chamber 61 (such as bearing overheating) mechanical abnormalities It means that it has occurred. In this case, an alarm indicating that the concentration in the crank chamber 61 is abnormal is output (S13). Specifically, the second warning lamp 45 is turned on. When it is determined that the density value N1 is smaller than the threshold P _12, the judgment result means that the oil mist concentration in the crank chamber 61 is not unusual.

When the concentration value N1 is determined to be less than the threshold value P ₁₂ in step S12, followed by concentration value N2 indicated by the digital data from the oil mist sensor 22 whether the threshold value P ₁₂ or more is determined (S14 ). Here, if it is determined that the density value N2 is the threshold value P ₁₂ or more, an alarm indicating that the crank chamber 63 is at a concentration abnormality is output (S15).

When the concentration value N2 is determined to be less than the threshold value P ₁₂ in step S14, followed by concentration value N3 shown by digital data from the oil mist sensor 23 whether the threshold value P ₁₂ or more is determined (S16 ). Here, if it is determined that the density value N3 is the threshold value P ₁₂ or more, an alarm indicating that the crank chamber 65 is at a concentration abnormality is output (S17).

When the concentration value N3 is determined to be less than the threshold value P ₁₂ in step S16, subsequently, the control unit 50 determines the oil mist concentration in the crank chamber 62 on the basis of the density value N1 and the density value N2. Specifically, in step S18, whether both of the density values N1 and concentration value N2 is the threshold value P ₁₁ or more is determined by the control unit 50. Here, if both the density values N1 and density value N2 is determined to be the threshold value P ₁₁ or more, the determination result, the threshold P ₁₂ over the crank chamber 62 located between the crank chamber 61 and the crank chamber 63 It means that the concentration of oil mist is generated (that oil mist concentration in the crank chamber 62 is the threshold value P ₁₂ or higher). In this case, an alarm indicating that the concentration in the crank chamber 62 is abnormal is output (S19).

When at least one of the density values N1 and density value N2 in step S18 is determined to be less than the threshold P _11, followed by the control unit 50, the oil in the crank chamber 64 on the basis of the density value N2 and the density value N3 Determine the mist concentration. Specifically, in step S20, whether both of the density value N2 and the density value N3 is the threshold value P ₁₁ or more is determined by the control unit 50. Here, if both the density value N2 and the density value N3 is determined to be the threshold value P ₁₁ or more, the determination result, the threshold P ₁₂ over the crank chamber 64 located between the crank chamber 63 and the crank chamber 65 It means that the concentration of oil mist is generated (that oil mist concentration in the crank chamber 64 is the threshold value P ₁₂ or higher). In this case, an alarm indicating that the concentration in the crank chamber 64 is abnormal is output (S21).

When at least one of the density values N2 and density value N3 is determined to be less than the threshold value P ₁₁ in step S20, processing is repeated in accordance with the re step S11 and subsequent steps.

  Since the oil mist concentration detection device 10 is configured in this manner, both the adjacent oil mist concentrations in both the crank chamber 62 corresponding to the second cylinder and the crank chamber 64 corresponding to the fourth cylinder can be detected directly. It is possible to determine whether the oil mist concentrations in the crank chamber 62 and the crank chamber 64 are abnormal from the oil mist concentration in the crank chamber. Further, by applying the oil mist concentration detection device 10 of the above-described embodiment to the engine 70, the detection points of the oil mist concentration detection can be reduced, so that the installation work and maintenance work of the oil mist concentration detection device 10 are reduced. .

  In the above-described embodiment, the oil mist concentration detection device 10 applied to the five-cylinder engine 70 is exemplified. However, for example, the oil mist of the present embodiment is applied to an engine of three cylinders, four cylinders, or six cylinders or more. The concentration detection apparatus 10 is preferably applied. Here, when the oil mist concentration detection device 10 is applied to each engine having a different number of cylinders, preferable detection points of the oil mist sensor are as shown in Table 1.

  As shown in Table 1, when the oil mist concentration detection device 10 is applied to a three-cylinder engine, it is preferable to install an oil mist sensor in a crank chamber corresponding to each of the first cylinder and the third cylinder. Further, when applied to a four-cylinder engine, a crank chamber corresponding to each of the first cylinder, the third cylinder, and the fourth cylinder, or a crank chamber corresponding to each of the first cylinder, the second cylinder, and the fourth cylinder. It is preferable to attach an oil mist sensor. That is, the oil mist sensor is always attached to the cylinders adjacent to the cylinder to which the oil mist sensor is not attached. By determining the detection point by the oil mist sensor in this way, it is possible to accurately determine the oil mist concentration in the crank chamber corresponding to the cylinder to which the oil mist sensor is not attached.

  As shown in Table 2, when every other detection point is determined for an engine having an even number of cylinders, one of the two cylinders arranged at both ends of the cylinder row is assigned to one of the cylinders. The oil mist sensor is not provided in the corresponding crank chamber. Here, when the oil mist sensor is not provided in the crank chamber corresponding to the fourth cylinder for the four-cylinder engine, the concentration detected by the oil mist sensor in the crank chamber corresponding to the third cylinder is monitored. Thus, the oil mist concentration in the crank chamber corresponding to the fourth cylinder can be predicted to some extent. However, it is impossible to distinguish whether there is an oil mist that cannot be evaluated as abnormal in the crank chamber corresponding to the third cylinder, or whether there is a concentration abnormality in the crank chamber corresponding to the fourth cylinder. The determination result is uncertain.

DESCRIPTION OF SYMBOLS 10 ... Oil mist density | concentration detection apparatus 21, 22, 23 ... Oil mist sensor 40 ... Controller 50 ... Control part 61-65 ... Crank chamber 70 ... Engine

Claims (4)

Oil mist concentration detection for detecting for each crank chamber an oil mist concentration in a crankcase having at least a first crank chamber, a second crank chamber, and a third crank chamber provided between the first crank chamber and the second crank chamber. A device,
A first sensor that outputs a signal representing the oil mist concentration in the first crank chamber;
A second sensor that outputs a signal representing the oil mist concentration in the second crank chamber;
An oil mist concentration detecting device comprising: a control unit having a determination unit that determines an oil mist concentration in the third crank chamber based on two output signals output from the first sensor and the second sensor, respectively. .   The determination unit is provided on the condition that a first output signal representing the first concentration or more and less than the second concentration is output as the oil mist concentration in the crank chamber corresponding to each sensor from each of the first sensor and the second sensor. The oil mist concentration detection device according to claim 1, wherein the oil mist concentration in the third crank chamber is determined to be equal to or higher than the second concentration. The control unit
On the condition that the second output signal indicating the second concentration or more is output from both or one of the first sensor and the second sensor, both the first crank chamber and the second crank chamber or Output an alarm indicating concentration abnormality in either one,
And a warning output unit that outputs a warning indicating an abnormal concentration in the third crank chamber on the condition that the determination unit determines that the oil mist concentration in the third crank chamber is equal to or higher than the second concentration. Item 3. The oil mist concentration detection device according to Item 2. The first concentration is determined based on measured data of output signals output from the first sensor and the second sensor when oil mist equal to or higher than the second concentration is generated in the third crank chamber. 4. The oil mist concentration detection device according to claim 2 or 3, which is a value.

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