Crankshaft phase measurement method, crankshaft and internal combustion engine

Abstract

To provide a crankshaft phase measurement method which can accurately measure a phase of a throw part.SOLUTION: A crankshaft phase measurement method is for measuring a phase of a crankshaft S by using a crankshaft phase control device 1 including: a non-contact sensor 10 for detecting a detection marker M provided on a throw part T of the crankshaft S of an internal combustion engine; and a calculation unit 20 for receiving detection data detected by the non-contact sensor 10 and performing calculation. The method includes: a step in which the non-contact sensor 10 detects a passage start time and a passage finish time of the detection marker M; and a step in which the calculation unit 20 calculates a passage time of a center of the detection marker M from detection data for the passage start time and the passage finish time.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a crankshaft phase measurement method, a crankshaft, and an internal combustion engine.

Background Art

[0002] In a cylinder of an internal combustion engine such as an automobile or a ship, the piston reciprocates to repeatedly perform intake and compression of air, combustion of an air-fuel mixture in which fuel is injected into the compressed air, and exhaust of combustion gas. The injection of the fuel may cause the fuel consumption rate (fuel efficiency) in the combustion to vary depending on the timing. Therefore, it is required to perform the injection of the fuel at an accurate timing.

[0003] A method of controlling the fuel injection timing by measuring the phase of the crankshaft is known. For example, a method of measuring the phase of a crankshaft using a crankshaft timing rotor (gear) arranged coaxially at the end of the crankshaft and rotating in synchronization with the crankshaft is known (Japanese Patent Application Laid-Open No. 2018-123735). In this phase measurement method, signal teeth serving as marks are provided in the rotor gear, and it is said that the phase of the crankshaft can be known by detecting the position of the signal teeth.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] In the phase measurement method described in the above-mentioned publication, the actual measurement is of the rotor phase, and this rotor phase is considered to be the phase of the crankshaft directly connected to the rotor. However, the crankshaft phase may differ from the rotor phase due to the effects of machining errors, torsional vibrations during operation, etc. Therefore, in order to inject the fuel at the correct timing, a method for more accurately measuring the crankshaft phase is required.

[0006] The present invention has been made based on the circumstances described above, and aims to provide a crankshaft phase measurement method and a crankshaft that can accurately measure the phase of the crankshaft, and an internal combustion engine that improves fuel consumption. [Means for solving the problem]

[0007] One aspect of the present invention, which solves the above problems, is a method for measuring the phase of a crankshaft using a crankshaft phase measuring device comprising a non-contact sensor that detects a detection marker arranged in the slow portion of the crankshaft of an internal combustion engine, and a calculation unit that receives and calculates the detection data detected by the non-contact sensor, the method comprising the steps of the non-contact sensor detecting the start and end times of passage of the detection marker, and the calculation unit calculating the time of passage through the center of the detection marker from the detection data of the start and end times of passage.

[0008] Another aspect of the present invention that solves the above problems is a crankshaft in which a detection marker for measuring the phase is provided in the slow section.

[0009] Another aspect of the present invention that solves the above problems is an internal combustion engine comprising a crankshaft disposed in a crankcase, a non-contact sensor that detects the detection marker, a calculation unit that receives and calculates the detection data detected by the non-contact sensor, and a control unit that instructs the fuel injector to inject fuel based on the calculation result of the calculation unit. [Effects of the Invention]

[0010] The crankshaft phase measurement method of the present invention can accurately measure the phase of the crankshaft by detecting a detection marker placed in the slow portion of the crankshaft. In the crankshaft of the present invention, the detection marker is placed and the position of the slow portion is detected with high precision, so the phase can be measured with high precision. The internal combustion engine of the present invention can improve fuel consumption rate because it can inject fuel at an optimal timing while accurately measuring the phase of the crankshaft. [Brief explanation of the drawing]

[0011] [Figure 1] Figure 1 is a conceptual diagram of a crankshaft phase measuring device used in a crankshaft phase measuring method according to one embodiment of the present invention. [Figure 2] Figure 2 is a schematic enlarged view of the slow section of the crankshaft shown in Figure 1. [Figure 3] Figure 3 is a schematic left side view of the throw section in Figure 2. [Figure 4] Figure 4 is a flowchart showing a crankshaft phase measurement method according to one embodiment of the present invention. [Figure 5] Figure 5 is a flowchart showing the details of the calculation process in Figure 4. [Figure 6] Figure 6 is a graph showing how the sensor potential of a non-contact sensor changes when the slow part comes into close proximity to the non-contact sensor. [Figure 7] Figure 7 is a graph showing how the sensor potential of a non-contact sensor changes when a detection marker comes into close proximity to the non-contact sensor. [Figure 8] Figure 8 is a graph showing the results of calculating the timing of passing through the center of the detection marker. [Modes for carrying out the invention]

[0012] One aspect of the present invention is a method for measuring the phase of a crankshaft in an internal combustion engine using a crankshaft phase measuring device comprising a non-contact sensor for detecting a detection marker disposed in the slow portion of the crankshaft, and a calculation unit for receiving and calculating detection data detected by the non-contact sensor, the method comprising the steps of the non-contact sensor detecting the start and end times of passage of the detection marker, and the calculation unit calculating the time of passage through the center of the detection marker from the detection data of the start and end times of passage.

[0013] The crankshaft phase measurement method uses a crankshaft phase measurement device that includes a detection marker placed in the slow portion of the crankshaft, a non-contact sensor that detects the detection marker, and a calculation unit that receives the detection data detected by the non-contact sensor and performs calculations. The non-contact sensor detects the start and end of passage of the detection marker. The calculation unit calculates the time of passage through the center of the detection marker from the detection data at the start and end of passage. In this way, the crankshaft phase measurement method can accurately determine the position of the slow portion in order to grasp the timing of passage through the center of the detection marker. Therefore, the phase of the crankshaft can be measured with high precision, and the fuel injection timing into the cylinder of the internal combustion engine can be easily optimized.

[0014] It is preferable that the detectable area of ​​the non-contact sensor is larger than the detectable area of ​​the detection marker in the detection direction of the non-contact sensor. By doing so, the start and end of passage of the detection marker can be detected with higher accuracy.

[0015] The detection marker is preferably formed of metal plating or a thin metal film and joined to the crankshaft. This allows the detection marker to be easily attached to the crankshaft.

[0016] It is preferable that the detection marker is formed by machining a part of the crankshaft. By doing so, the crankshaft phase measuring device can have a simple configuration.

[0017] Another aspect of the present invention is a crankshaft in which a detection marker for measuring the phase is arranged in a slow part.

[0018] Since the detection marker is arranged on the crankshaft and the position of the slow part is detected with high precision, the phase can be easily measured.

[0019] Still another aspect of the present invention is an internal combustion engine including a non-contact sensor that detects the detection marker disposed in a crankcase, a calculation unit that receives and calculates detection data detected by the non-contact sensor, and a control unit that instructs a fuel injector to inject fuel based on a calculation result of the calculation unit.

[0020] Since the internal combustion engine is provided with the crankshaft and can inject fuel at a suitable timing while accurately measuring the phase of the crankshaft, the fuel consumption rate can be improved.

[0021] [Details of the Mode for Carrying Out the Invention] Hereinafter, an embodiment of the crankshaft phase measurement method of the present invention will be described.

[0022] The crankshaft phase measurement method measures the phase of the crankshaft using a crankshaft phase measurement device including a non-contact sensor that detects a detection marker disposed in a slow part of the crankshaft in an internal combustion engine, and a calculation unit that receives and calculates detection data detected by the non-contact sensor. The crankshaft phase measurement method includes a step in which the non-contact sensor detects the start time and the end time of passing of the detection marker, and a step in which the calculation unit calculates the passing time of the center of the detection marker from the detection data at the start time and the end time of passing.

[0023] <Crankshaft Phase Measurement Device> The crankshaft phase measuring device, as shown in Figures 1, 2, and 3, is a device 1 for measuring the phase of a crankshaft S in an internal combustion engine, which is not shown in its entirety, and comprises a non-contact sensor 10 and a calculation unit 20. The crankshaft S is one of the components that make up the internal combustion engine. The crankshaft S is a rotating shaft, and the rotational motion of the crankshaft S is transmitted to the wheels of a vehicle, the propeller of a ship, etc., to become the propulsion force of the vehicle, ship, etc. In other words, the crankshaft S is an output shaft. Note that the components (components) in each figure showing the crankshaft phase measuring device 1 are shown schematically, and their shape and scale may differ from the actual components.

[0024] A portion of the crankshaft S is housed within the crankcase C, which constitutes a part of the internal combustion engine. This portion is provided with a slow section (crank slow) T. That is, the crankshaft S has a shaft section S1 and slow sections T. In this embodiment, six slow sections T are provided. The six slow sections T are arranged at approximately equal intervals in the axial direction of the crankshaft S and at approximately equal angular intervals when viewed from the axial direction of the crankshaft S. One slow section T and another slow section T adjacent to this one slow section T are connected by the shaft section S1. The number of slow sections T2 is not limited to six and varies depending on the configuration of the internal combustion engine.

[0025] The slow section T is cylindrical and has a crank pin T2 positioned axially parallel to and offset from the axial direction of the crankshaft S, and a pair of roughly plate-shaped crank arms T1 for holding the crank pin T2. ​​On the tip side of the crank arm T1 (the end side spaced away from the crankshaft S), a bag chamfered section T11 is formed on the side opposite to the side holding the crank pin T2 (outer surface), with the thickness gradually decreasing towards the tip side. A connecting rod (not shown) is attached to the crank pin T2, and this connecting rod is connected to a piston (not shown). The piston reciprocates within a cylinder (not shown), and rotates the slow section T via the connecting rod, thereby imparting rotational motion to the crankshaft S. The connecting rod, piston, and cylinder are all parts of the internal combustion engine.

[0026] Each slow section T is equipped with a detection marker M. The position of the detection marker M is not particularly limited, but in this embodiment, the detection marker M is positioned approximately in the center of the bag chamfer section T11 on one of the crank arms T1 of the slow section T.

[0027] The non-contact sensor 10 detects the detection markers M. The non-contact sensor 10 in this embodiment is a proximity sensor and is positioned inside the crankcase C so as to be able to approach each detection marker M. The non-contact sensor 10 detects the start and end of the passage of the detection markers M. That is, the detection of the detection markers M by the non-contact sensor 10 begins when the detection marker M enters the detection range of the non-contact sensor 10 and ends when the detection marker M leaves the detection range of the non-contact sensor 10.

[0028] The detection marker M is not particularly limited as long as it can be detected by the non-contact sensor 10, but it is preferable that it is formed of metal plating or a thin metal film and can be joined to the crankshaft S. The metal is preferably different from the material of the crank arm T1, and examples include copper and aluminum. The non-contact sensor 10 is not particularly limited as long as it can detect the detection marker M, but if the detection marker M is formed of metal plating or a thin metal film, an eddy current displacement sensor is an example.

[0029] The shape of the detection marker M is not particularly limited and can be circular, elliptical, triangular, rectangular, or polygonal. The size of the detection marker M in plan view (detectable area) is not particularly limited, but it is preferably less than or equal to the detection range (area of ​​the detectable region) of the non-contact sensor 10. In other words, it is preferable that the detectable region of the non-contact sensor 10 is larger than the detectable area of ​​the detection marker M in the detection direction of the non-contact sensor 10.

[0030] If the detection marker M is too large relative to the detection range of the non-contact sensor 10, the sensor output of the non-contact sensor 10 may saturate, making it difficult to accurately determine the timing of passage through the center of the detection marker M. On the other hand, if the detection marker M is too small, the change in the sensor output of the non-contact sensor 10 will be small, which may lead to unstable detection of the detection marker M. Therefore, the size of the detection marker M should be determined to be smaller than the detection range of the non-contact sensor 10, and to have an area that provides a sufficiently large sensor output to withstand the noise superimposed on the non-contact sensor 10 in the detection environment.

[0031] The calculation unit 20 receives detection data detected by the non-contact sensor 10. The calculation unit 20 calculates the timing of the passage of the center of the detection marker M from the detection data at the start and end of the passage of the detection marker M detected by the non-contact sensor 10. Specifically, the calculation unit 20 calculates the time when the central part of the detection marker M passed through the detection range from the time when the detection marker M entered the detection range of the non-contact sensor 10 and the time when the detection marker M left the detection range of the non-contact sensor 10.

[0032] The calculation unit 20 transmits the calculation result to the control unit 30 of the internal combustion engine. Based on the calculation result, the control unit 30 instructs the fuel injector (not shown) installed in the internal combustion engine to inject fuel. The calculation unit 20 and the control unit 30 may be configured as a single unit.

[0033] <Crankshaft Phase Measurement Method> The crankshaft phase measurement method, using the crankshaft phase measurement device described above, includes a step S1 in which the non-contact sensor 10 detects the start and end times of passage of the detection marker M, as shown in Figure 4, and a step S2 in which the calculation unit 20 calculates the time of passage through the center of the detection marker M from the detection data of the start and end times of passage. In Figure 4, "start" refers to the starting of the internal combustion engine, and "end" refers to the stopping of the internal combustion engine.

[0034] In detection step S1, the non-contact sensor 10 detects the start and end of the passage of the detection marker M. That is, the detection of the detection marker M by the non-contact sensor 10 begins when the detection marker M enters the detection range of the non-contact sensor 10 and ends when the detection marker M leaves the detection range of the non-contact sensor 10.

[0035] In calculation step S2, the calculation unit 20 calculates the time when the object passes the center of the detection marker M from the detection data at the start and end of passage. Specifically, as shown in Figure 5, calculation step S2 includes a step S21 for monitoring the sensor output of the non-contact sensor 10, a step S22 for detecting a decrease in the sensor output of the non-contact sensor 10, a step S23 for detecting a change in the sensor output of the non-contact sensor 10 where the sensor output has decreased, a step S24 for detecting the end of the change in the sensor output, a step S25 for calculating the position of the center of the detection marker M, a step S26 for detecting the end of the decrease in the sensor output of the non-contact sensor 10, and a step S27 for detecting the stop of the internal combustion engine.

[0036] In the sensor output monitoring step S21, the calculation unit 20 monitors the sensor output of the non-contact sensor 10. The monitoring of the sensor output is performed continuously. In other words, the calculation unit 20 constantly monitors the sensor output while the internal combustion engine is operating.

[0037] In the sensor output reduction detection process S22, the calculation unit 20 detects a decrease in the sensor output of the non-contact sensor 10. The sensor output of the non-contact sensor 10 decreases when the slow part T enters the detection range of the non-contact sensor 10. The calculation unit 20 detects the start of this decrease in sensor output.

[0038] In the sensor output change detection step S23, the calculation unit 20 detects a change in the sensor output of the non-contact sensor 10 where the sensor output is decreasing. When the non-contact sensor 10, which is detecting the slow portion T, detects the detection marker M, the sensor output changes. The calculation unit 20 detects the start of this change in sensor output.

[0039] In the sensor output change termination detection step S24, the calculation unit 20 detects the termination of the change in the sensor output. When the detection marker M leaves the detection range of the non-contact sensor 10, the sensor output of the non-contact sensor 10 returns to a reduced state. The calculation unit 20 detects that the sensor output has returned to a reduced state, that is, that the detection marker M has left the detection range of the non-contact sensor 10.

[0040] In calculation step S25, the calculation unit 20 calculates the position of the center of the detection marker M. Specifically, it calculates the passage time of the detection marker M from the detection of the start and end of the change in the sensor output, and calculates the passage time of the central part of the detection marker M based on this calculation result. From this calculation result, the position of the detection marker M, and thus the position of the slow part T, can be accurately determined, so the phase of the crankshaft S can be measured with high precision.

[0041] In the sensor output reduction termination detection step S26, the calculation unit 20 detects the end of the decrease in the sensor output of the non-contact sensor 10. The decrease in the sensor output of the non-contact sensor 10 ends when the slow part T moves out of the detection range of the non-contact sensor 10. The calculation unit 20 detects this end of the decrease in sensor output and proceeds back to the sensor output monitoring step S21.

[0042] In the stop detection step S27, the calculation unit 20 detects that the internal combustion engine has stopped, and the crankshaft measurement step ends.

[0043] <Advantages> The crankshaft phase measurement method involves attaching a detection marker M to the bag chamfered portion T11 in the slow portion T of the crankshaft S, and a non-contact sensor 10 detects the passage of the detection marker M. By calculating the passage of the central portion of the detection marker M from this detection, the position of the slow portion T can be accurately determined, allowing for high-precision measurement of the crankshaft S's phase, taking into account the effects of torsional vibration and machining errors.

[0044] The embodiments disclosed above should be considered in all respects to be illustrative and not restrictive. The scope of the present invention is not limited to the configurations of the embodiments described above, but is indicated by the claims, and all modifications within the meaning and scope equivalent to the claims are intended to be included.

[0045] In the embodiments described above, the detection marker was described as being made of a metal material and disposed on the bag chamfer portion of the crank arm, but it is not limited to this. The detection marker may be provided, for example, by machining a part of the throw portion. Specifically, recesses, holes, etc., may be provided on the surface of the bag chamfer portion, or a part of the surface of the bag chamfer portion may be machined, such as by roughening, and the machined portion may be used as the detection marker. The detection marker is not particularly limited as long as it changes electromagnetic properties such as conductivity and permeability locally in space and can be detected by a non-contact sensor.

[0046] The location (location) where the detection marker is placed is not limited to the bag chamfer section, but may be placed anywhere on the crankshaft as long as it is possible to detect the rotation of the crankshaft.

[0047] The non-contact sensor may be located outside the crankcase, provided that the detection marker is detectable.

[0048] The non-contact sensor, the calculation unit, and the control unit may be electrically connected, or they may communicate with each other by wireless communication means. [Examples]

[0049] The following describes embodiments of the present invention. The present invention is not limited to the following embodiments.

[0050] An eddy current displacement sensor was installed close to the rotating slow section, and the crankshaft was rotated at 30 rpm. The output of the eddy current displacement sensor was converted by A / D (Analog / Digital) and analyzed, resulting in the waveform shown in Figure 6. From Figure 6, it can be seen that the sensor output decreases when the slow section approaches the eddy current displacement sensor. Thus, the decrease in sensor output clearly distinguishes between the state where the slow section is close to the eddy current displacement sensor and the state where it is not. However, since the sensor output becomes flat when passing over the slow section, it is difficult to accurately determine the timing of passage over an arbitrary specific point in the slow section. On the other hand, considering the use of the sensor output for fuel injection timing, it is preferable to be able to determine the phase of the crankshaft with an accuracy of 0.1° or less.

[0051] A detection marker that changes the sensor output was placed at an arbitrary point on the bag chamfer of the crank arm in the slow section. Specifically, a 10mm square, 0.08mm thick copper foil was attached to the bag chamfer for the experiment. While monitoring the sensor output, the timing of the start of passage through the slow section was recognized, then the start of passage of the detection marker (a threshold value was set for the time derivative) was detected, and the timing of passage through the center of the detection marker (time derivative = 0) was detected. The results are shown in Figure 7. In Figure 7, the convex portion (raised portion) visible approximately in the center of the flat portion where the sensor output decreased represents the change in sensor output due to the detection of the detection marker.

[0052] Since some noise is superimposed when detecting changes in sensor output, instead of calculating the derivative of the digital data sampling interval at two points, it may be better to calculate the derivative using the acquired timing data and several preceding data points, depending on the noise situation. Figure 8 shows the experimental results of calculating the timing of passage through the center of the detection marker using such an algorithm. In Figure 8, the circular points represent the passage time, and the angular points represent the difference between the preceding and succeeding passage times. Looking at the difference in passage time, it can be seen that all points fall within the range of ±0.5 msec. When converted to angles and expressed as a statistical value, 1σ ≈ 0.01 deg., indicating that the timing of passage through the center of the detection marker can be detected with very high accuracy. [Industrial applicability]

[0053] The crankshaft phase measurement method of the present invention can accurately measure the phase of the crankshaft S, and is therefore suitable for use in internal combustion engines equipped with a crankshaft. [Explanation of Symbols]

[0054] 1. Crankshaft Phase Measurement Device 10 Non-contact sensors 20 Arithmetic section 30 Control Unit S Crankshaft S1 Shaft Section T Throw section T1 Crank Arm T2 Crankpin T11 Bag Champhala Section M Marker

Claims

1. A method for measuring the phase of a crankshaft using a crankshaft phase measuring device comprising a non-contact sensor that detects a detection marker joined to the crank arm of the crankshaft of an internal combustion engine, or a detection marker formed by machining a part of the crank arm of the crankshaft, and a calculation unit that receives the detection data detected by the non-contact sensor and performs calculations, wherein The non-contact sensor includes the steps of detecting the start and end of passage of the detection marker, The calculation unit performs the following steps: calculates the time of passage through the center of the detection marker from the detection data at the start and end of passage. A crankshaft phase measurement method characterized by having the following features.

2. The crankshaft phase measurement method according to claim 1, wherein the detectable area of ​​the non-contact sensor is larger than the detected area of ​​the detection marker in the detection direction of the non-contact sensor.

3. The crankshaft phase measurement method according to claim 1 or claim 2, wherein the detection marker joined to the crank arm is formed of metal plating or a thin metal film.

4. A crankshaft for an internal combustion engine having a detection marker joined to a crank arm, or a detection marker formed by machining a part of a crank arm.

5. The crankshaft described in claim 4 is arranged inside the crankcase, A non-contact sensor for detecting the aforementioned detection marker, This non-contact sensor receives detection data and performs calculations on the calculation unit, A control unit that instructs the fuel injector to inject fuel based on the calculation result of the calculation unit. An internal combustion engine equipped with [a specific feature / ability].

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