JP5309705B2 - Film thickness measuring apparatus and film thickness measuring method - Google Patents

Description

  The present invention relates to a film thickness measuring device and a film thickness measuring method.

  Conventionally, as one of the devices for measuring the film thickness of the oil film inside the engine cylinder, the capacitance of the gap between the piston ring on which the oil film is formed and the cylinder is measured, and the film thickness is based on the measured capacitance. There is known a film thickness measuring apparatus that calculates the above (for example, see Patent Document 1).

Moreover, in order to confirm the soundness of the film thickness measuring device described in Patent Document 1, in a state where the engine equipped with the film thickness measuring device is not operating, the film thickness measuring device is used by using a capacitance measuring device. Has confirmed the soundness (disconnection, adhesion of foreign matter, dent of the sensor, etc.) of the capacitance type sensor included in.
JP 2007-107947 A

  However, there is a problem that it takes time to perform measurement using a capacitance measuring instrument and to check the soundness of the capacitance type sensor against past data. In addition, when the engine is mounted on a ship, there is a problem that the soundness of the capacitive sensor cannot be confirmed during voyage.

  The present invention has been made to solve the above-described problems, and can easily check the soundness of the capacitive sensor, and the capacitive sensor can be used even when the engine is operating. It aims at providing the film thickness measuring apparatus and film thickness measuring method which can confirm soundness.

  According to the present invention, an oil film of a lubricating oil formed in the gap is detected by detecting the capacitance of the gap between the piston ring and the piston ring sliding surface of the cylinder liner. A film thickness measuring device for measuring a film thickness, wherein the electrostatic capacity is charged by supplying a constant current to the electrode, and the electrostatic capacity is detected based on a change in charging voltage accompanying the charging. And comparing a capacitance detection unit that outputs a detection signal indicating the capacitance, the capacitance based on the detection signal output by the capacitance detection unit, and a predetermined threshold, A film thickness measuring apparatus comprising: a determination unit that determines whether or not an abnormality has occurred in the film thickness measuring apparatus.

  The present invention further includes a crank rotation angle detection unit that detects a crank rotation angle indicating a position of the piston ring with respect to the piston ring sliding surface, and the determination unit compares the capacitance with the threshold value. The electrostatic capacitance detected in a state where the electrode and the piston ring are opposed to each other and a threshold value different between the electrostatic capacitance detected in a state where the electrode and the piston ring are not opposed to each other. It is a film thickness measuring apparatus characterized by being used.

  The present invention also provides a lubricant oil formed in the gap by detecting the electrostatic capacitance of the gap between the piston ring and one or more electrodes provided on the same plane as the piston ring sliding surface of the cylinder liner. A film thickness measurement method for measuring a film thickness of an oil film, wherein the electrostatic capacity is charged by supplying a constant current to the electrode, and the electrostatic capacity is based on a change in charging voltage associated with the charging. And detecting a capacitance indicating the capacitance, and comparing the capacitance based on the detection signal output in the capacitance detection step with a predetermined threshold value. And a determination step for determining whether or not an abnormality has occurred in the film thickness measuring apparatus.

  The present invention further includes a crank rotation angle detection step of detecting a crank rotation angle indicating a position of the piston ring with respect to the piston ring sliding surface, and the determination step includes comparing the capacitance with the threshold value. In addition, the electrostatic capacitance detected in a state where the electrode and the piston ring are opposed to each other and a threshold value which is different from the electrostatic capacitance detected in a state where the electrode and the piston ring are not opposed to each other Is a method for measuring a film thickness.

  According to the present invention, the soundness of the capacitive sensor can be easily confirmed, and the soundness of the capacitive sensor can be confirmed even when the engine is operating.

  Hereinafter, an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a configuration diagram showing a functional configuration of a film thickness measuring apparatus in the present embodiment. In the illustrated example, the film thickness measuring device includes a capacitance sensor 1, a signal conversion unit 2 (C / V converter), a signal processing unit 3, an encoder 4, and a storage unit 5.

  As is conventionally known, the film thickness measuring apparatus according to the present embodiment includes a capacitance sensor 1 provided on the inner wall surface (piston ring sliding surface) of the cylinder liner 6 and a piston ring 8 provided on the piston 7. And the thickness of the oil film of the lubricating oil formed in the gap between the capacitance sensor 1 and the piston ring 8 is measured based on the detected capacitance. .

  When the capacitance sensor 1 and the piston ring 8 face each other, a measurement capacitor using an oil film formed in a gap between the capacitance sensor 1 and the piston ring 8 as a dielectric is configured. Therefore, the film thickness of the oil film can be obtained by detecting the capacitance between the capacitance sensor 1 and the piston ring 8.

  The capacitance sensor 1 detects the capacitance between the capacitance sensor 1 and the piston ring 8. The signal converter 2 is a C / V converter, and converts the capacitance detected by the capacitance sensor 1 into a voltage (output voltage value). The encoder 4 (crank rotation angle detector) detects the angle of a crank (not shown) provided in the engine.

  Since the position of the piston ring 8 is uniquely determined according to the crank angle, the position of the piston ring 8 can be calculated based on the crank angle detected by the encoder 4. The signal processing unit 3 calculates the positional relationship between the capacitance sensor 1 and the piston ring 8 based on the crank angle detected by the encoder 4, and at the time when the capacitance sensor 1 detects the capacitance. The positional relationship between the piston ring 8 and the capacitance sensor 1 is determined.

  Further, the signal processing unit 3 calculates a capacity conversion voltage value from the output voltage value converted by the signal conversion unit 2 and the correction voltage value. Subsequently, the signal processing unit 3 calculates the capacitance between the capacitance sensor 1 and the piston ring 8 based on the capacitance conversion voltage value. Subsequently, the signal processing unit 3 calculates the film thickness of the oil film based on the calculated capacitance.

  In addition, the signal processing unit 3 determines the calculated capacitance value and the positional relationship between the piston ring 8 and the capacitance sensor 1 when the capacitance sensor 1 detects the capacitance (the piston ring 8 is And whether or not it is the timing when it has passed through the capacitance sensor 1 is stored in the storage unit 5 in association with each other.

  In addition, the signal processing unit 3 determines the soundness of the capacitance sensor 1. The determination method will be described later.

  Next, the difference between the crank angle and the capacitance will be described with reference to FIG. FIG. 2 is a diagram showing the relationship between the capacitance between the capacitance sensor 1 and the piston ring 8 and the crank angle of the engine in the present embodiment. The difference in capacitance is a difference between the capacitance calculated by the signal processing unit 3 and the capacitance when the piston ring does not pass through the capacitance sensor 1.

  In the illustrated example, the difference in capacitance is large at a predetermined crank angle. The case where the difference in capacitance becomes large is when the piston ring 8 and the capacitance sensor 1 face each other. Thus, the relationship between the difference in capacitance and the crank angle is uniquely determined. Therefore, by determining in advance the crank angle when the piston ring 8 and the capacitance sensor 1 face each other, the positional relationship between the piston ring 8 and the capacitance sensor 1 can be determined based on the crank angle. it can.

  Next, the capacitance when an abnormality occurs in the capacitance sensor 1 will be described. FIG. 3 is a diagram showing the relationship between the difference in capacitance from the initial value and time in a state where the piston ring 8 does not pass through the capacitance sensor 1.

  When there is no failure in the capacitance sensor 1, the capacitance measured in a state where the piston ring 8 does not pass through the capacitance sensor 1 is set as an initial value when not passing, and when not passing The difference between the initial value and the capacitance calculated by the signal processing unit 3 is the difference in capacitance from the initial value. Specifically, when the engine is mounted on a ship, the piston ring 8 is used in a state where the piston ring 8 does not pass through the capacitance sensor 1 by using a capacitance measuring device before a land test or departure. And the electrostatic capacitance sensor 1 are measured, and the measured value is set as an initial value when no passage is made. Further, the storage unit 5 stores the initial value at the time of non-passing.

  In the example shown in the figure, when a foreign substance such as water or gas enters the cylinder, the difference in capacitance from the initial value is large. This is because the capacitance between the piston ring 8 and the capacitance sensor 1 increases due to the mixing of foreign matter. Further, when the cable connected to the capacitance sensor 1 is disconnected, the difference in capacitance from the initial value is small. This is because the capacitance between the piston ring 8 and the capacitance sensor 1 cannot be measured because the cable is disconnected.

  Therefore, in a state where the piston ring 8 does not pass through the capacitance sensor 1, the difference in capacitance from the initial value is within a preset range between the lower threshold when not passing and the upper threshold when not passing Therefore, the soundness of the capacitance sensor 1 can be determined. In the present embodiment, the storage unit 5 stores in advance a lower limit threshold value when not passing and an upper limit threshold value when not passing.

  FIG. 4 is a diagram showing the relationship between time and the difference in the average value of the capacitance from the initial value in a state where the piston ring 8 passes through the capacitance sensor 1.

  When no trouble has occurred in the capacitance sensor 1, the capacitance measured with the piston ring 8 passing through the capacitance sensor 1 is set as the initial value at the time of passage, and the initial value at the time of passage. The difference between the value and the average value of the integrated capacitance values calculated by the signal processing unit 3 is defined as the difference in the average capacitance value from the initial value. Specifically, when the engine is mounted on a ship, the piston ring 8 is in a state where the piston ring 8 passes through the capacitance sensor 1 by using a capacitance measuring device before a land test or departure. The capacitance between the sensor and the capacitance sensor 1 is measured, and the measured value is set as the initial value when passing. The storage unit 5 stores an initial value at the time of passing.

  Moreover, as an average value of the integrated value of the capacitance calculated by the signal processing unit 3, a plurality of capacitances when the piston ring 8 passes through the capacitance sensor 1 are acquired, and the average of the acquired capacitances Value. Further, when the piston 7 includes a plurality of piston rings 8, the average value of the capacitance may be calculated for each piston ring 8, and the average value of the capacitance is calculated for all the piston rings 8. Also good.

  In the example shown in the figure, when a foreign object adheres to the capacitance sensor 1 or the piston ring 8, the difference in the average value of the capacitance from the initial value is large. This is because when a foreign substance adheres to the capacitance sensor 1 or the piston ring 8, the capacitance between the piston ring 8 and the capacitance sensor 1 increases. Further, when the capacitance sensor 1 is recessed, the difference between the average value of the capacitance and the initial value is small. This is because the capacitance between the piston ring 8 and the capacitance sensor 1 becomes small because the capacitance sensor 1 is recessed.

  Therefore, in a state where the piston ring 8 passes through the capacitance sensor 1, the difference between the initial value and the average value of the capacitance is a preset lower limit threshold value during passage and upper limit threshold value during passage. By determining whether or not the range is exceeded, the soundness of the capacitance sensor 1 can be determined. In the present embodiment, the storage unit 5 stores in advance a lower limit threshold during passage and an upper limit threshold during passage.

  Next, a procedure for determining the soundness of the capacitance sensor 1 in the present embodiment will be described with reference to FIG. FIG. 5 is a flowchart showing a procedure for determining the soundness of the capacitance sensor 1 in the present embodiment.

  (Step S101) The signal processing unit 3 calculates the capacitance value calculated by itself and the positional relationship between the piston ring 8 and the capacitance sensor 1 when the capacitance sensor 1 detects the capacitance. Is obtained from the storage unit 5. Thereafter, the process proceeds to step S102.

  (Step S <b> 102) The signal processing unit 3 determines whether the failure of the capacitance sensor 1 is performed based on information when the piston ring 8 passes through the capacitance sensor 1. If it is determined that the piston ring 8 is to be performed based on the information when it passes through the capacitance sensor 1, the process proceeds to step S111, otherwise the process proceeds to step S103.

  (Step S <b> 103) The signal processing unit 3 determines the electrostatic capacity of the piston ring 8 and the electrostatic capacitance measured when no trouble has occurred in the capacitance sensor 1 in a state where the piston ring 8 does not pass through the capacitance sensor 1. An initial value at the time of non-passing, which is a capacitance with the capacitance sensor 1, is read from the storage unit 5. Thereafter, the process proceeds to step S104.

  (Step S104) The signal processing unit 3 selects the capacitance when the piston ring 8 does not pass through the capacitance sensor 1 from the data read in Step S101, and the step is performed from the selected capacitance. The initial value at the time of non-passage read in S103 is subtracted, and the difference in capacitance from the initial value is calculated. Subsequently, the signal processing unit 3 determines whether or not the difference in capacitance from the initial value is smaller than the lower limit threshold value during non-passage stored in the storage unit 5. If it is determined that the value is smaller, the process proceeds to step S105. Otherwise, the process proceeds to step S107.

(Step S105) The signal processing unit 3 determines that the cable connected to the capacitance sensor 1 is disconnected. Thereafter, the process proceeds to step S106.
(Step S106) The signal processing unit 3 causes the display unit (not shown) to display a disconnection location confirmation request message. Thereafter, the process ends.

  (Step S <b> 107) The signal processing unit 3 determines whether or not the difference in capacitance from the initial value calculated in step S <b> 104 is larger than the upper limit threshold value during non-passage stored in the storage unit 5. If it is determined that the value is larger, the process proceeds to step S108. Otherwise, the process proceeds to step S110.

(Step S108) The signal processing unit 3 determines that foreign matter has entered the cylinder due to water leakage or gas leakage. Thereafter, the process proceeds to step S109.
(Step S109) The signal processing unit 3 displays a confirmation request message for water leakage and gas leakage on a display unit (not shown). Thereafter, the process ends.
(Step S110) The signal processing unit 3 determines that the capacitance sensor 1 is operating normally. Thereafter, the process ends.

  (Step S <b> 111) The signal processing unit 3 determines that the electrostatic capacitance sensor 1 and the electrostatic capacitance sensor 1 measured when the piston ring 8 passes through the electrostatic capacitance sensor 1 and no failure has occurred in the electrostatic capacitance sensor 1. An initial value at the time of passage, which is a capacitance with the capacitance sensor 1, is read from the storage unit 5. Thereafter, the process proceeds to step S112.

  (Step S112) The signal processing unit 3 selects a plurality of capacitances when the piston ring 8 passes through the capacitance sensor 1 from the data read out in step S101, and integrates the selected capacitances. Calculate the average value. Thereafter, the process proceeds to step S113.

  (Step S113) The signal processing unit 3 subtracts the initial value at the time of passage read in Step S111 from the average value of the integrated value of the capacitance calculated in Step S112, and the average value of the capacitance with the initial value. Calculate the difference. Subsequently, the signal processing unit 3 determines whether or not the difference in the average value of the capacitance from the initial value is smaller than the lower limit threshold value during passage stored in the storage unit 5. If it is determined that the value is smaller, the process proceeds to step S114. Otherwise, the process proceeds to step S116.

(Step S114) The signal processing unit 3 determines that the capacitance sensor 1 is recessed. Thereafter, the process proceeds to step S115.
(Step S115) The signal processing unit 3 causes the display unit (not shown) to display a sensor dent confirmation request message. Thereafter, the process ends.

  (Step S116) The signal processing unit 3 determines whether or not the difference in capacitance from the initial value calculated in step S113 is larger than the upper limit threshold value during passage stored in the storage unit 5. If it is determined that the value is larger, the process proceeds to step S117. Otherwise, the process proceeds to step S119.

(Step S <b> 117) The signal processing unit 3 determines that a foreign substance is attached to the surface of the capacitance sensor 1. Thereafter, the process proceeds to step S118.
(Step S118) The signal processing unit 3 causes a display unit (not shown) to display a confirmation request message for foreign matter adhesion on the sensor surface. Thereafter, the process ends.
(Step S119) The signal processing unit 3 determines that the capacitance sensor 1 is operating normally. Thereafter, the process ends.

  As described above, the capacitance between the piston ring 8 and the capacitance sensor 1 when no abnormality has occurred, and between the piston ring 8 and the capacitance sensor 1 when the engine is operating. The soundness of the capacitance sensor 1 can be determined on the basis of the capacitance. Thereby, the soundness of the capacitance sensor can be easily confirmed, and the soundness of the capacitance sensor can be confirmed even when the engine is operating.

  In addition, when it is detected that a failure has occurred, the abnormality content of the capacitance sensor 1 is also displayed, so that it is easy to check the soundness of the capacitance sensor 1, and the time required for the check is also long. It can be shortened.

  The embodiment of the present invention has been described in detail with reference to the drawings. However, the specific configuration is not limited to this embodiment, and includes designs and the like that do not depart from the gist of the present invention.

  For example, in the present embodiment, an example in which the film thickness measuring device is applied to an engine has been described.

It is the block diagram which showed the function structure of the film thickness measuring apparatus in one Embodiment of this invention. It is the figure which showed the relationship between the electrostatic capacitance between the electrostatic capacitance sensor and piston ring in this embodiment, and the crank angle of an engine. It is the figure which showed the difference of the electrostatic capacitance with the initial value in this embodiment, and the relationship with time. It is the figure which showed the relationship of the difference of the average value of the electrostatic capacitance with the initial value in this embodiment, and time. It is the flowchart which showed the procedure which judges the soundness of the electrostatic capacitance sensor in this embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Capacitance sensor, 2 ... Signal conversion part, 3 ... Signal processing part, 4 ... Encoder, 5 ... Memory | storage part, 6 ... Cylinder liner, 7 ... Piston , 8 ... Piston ring

Claims (2)

Measures the film thickness of the oil film formed in the gap by detecting the capacitance of the gap between the piston ring and the piston ring sliding surface of the cylinder liner. A film thickness measuring device that performs
The capacitance is charged by supplying a constant current to the electrode, the capacitance is detected based on a change in charging voltage accompanying the charging, and a detection signal indicating the capacitance is output. A capacitance detector;
A determination unit that compares the capacitance based on the detection signal output by the capacitance detection unit with a predetermined threshold and determines whether or not an abnormality has occurred in the film thickness measurement device;
A crank rotation angle detection unit that detects a crank rotation angle indicating a position of the piston ring with respect to the piston ring sliding surface;
When the determination unit compares the capacitance and the threshold, the capacitance detected in a state where the electrode and the piston ring face each other, and the electrode and the piston ring are A film thickness measuring apparatus using a threshold value different from the capacitance detected in a state of not facing each other . Measures the film thickness of the oil film formed in the gap by detecting the capacitance of the gap between the piston ring and the piston ring sliding surface of the cylinder liner. A film thickness measuring method for
The capacitance is charged by supplying a constant current to the electrode, the capacitance is detected based on a change in charging voltage accompanying the charging, and a detection signal indicating the capacitance is output. A capacitance detection step;
A determination step for comparing the capacitance based on the detection signal output in the capacitance detection step with a predetermined threshold and determining whether or not an abnormality has occurred in the film thickness measurement device;
A crank rotation angle detection step for detecting a crank rotation angle indicating a position of the piston ring with respect to the piston ring sliding surface, and
In the determination step, when comparing the capacitance and the threshold, the capacitance detected in a state where the electrode and the piston ring face each other, and the electrode and the piston ring A method for measuring a film thickness, comprising using a different threshold value for the capacitance detected in a state of being not opposed to each other.

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