Bearing metal missing part inspection method and bearing metal missing part inspection device

Abstract

To provide a defect inspection method for a bearing metal and a defect inspection device for a bearing metal that are able to detect, with a simple configuration, a defect in a bearing metal.SOLUTION: The method includes: a preparation step of arranging a pair of bearings such that inner peripheral surfaces thereof face each other; a fastening step of fastening the pair of bearings to each other by using a first bolt and a second bolt located on both sides in a second direction with an axis of a crankshaft interposed therebetween, in such order that the second bolt is fastened after the first bolt; and a determination step of determining whether a bearing metal has been attached, based on a fastening torque and a fastening angle when the pair of bearings are fastened by the second bolt.SELECTED DRAWING: Figure 6

Description

[Technical Field]

[0001] The present invention relates to a method and an apparatus for inspecting a bearing metal for missing parts. [Background technology]

[0002] An engine is provided with a bearing that rotatably supports a crankshaft and a bearing metal attached to the bearing. As disclosed in Patent Document 1, when an engine is assembled, an inspection process is carried out to check whether the bearing metal is attached to the bearing, that is, to check for missing bearing metal.

[0003] Patent Document 1 discloses a method for inspecting for missing bearing metal attached to the big end of a connecting rod. This method involves supplying air to a lubricating oil passage that opens onto the outer peripheral surface of the crankpin while the crankpin of a crankshaft is connected to the connecting rod, and determining that the bearing metal is missing if the pressure of this air supply is low. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2015-194384 Summary of the Invention [Problem to be solved by the invention]

[0005] When using the inspection method disclosed in Patent Document 1, it is necessary to provide a device for supplying air to the lubricating oil passage in addition to the device for assembling the engine, and it is also necessary to carry out a process for supplying air to the lubricating oil passage in addition to the engine assembly process, which results in the problem of complicated devices and processes.

[0006] The present invention has been made in consideration of the above circumstances, and aims to provide a bearing metal missing part inspection method and bearing metal missing part inspection device that can detect missing bearing metal parts with a simple configuration. [Means for solving the problem]

[0007] As a result of extensive research into the above-mentioned problem, the inventors of the present application have discovered the following: When a method of fastening a pair of half-shaped bearings with bolts at both sides thereof is used in which one half is fastened first and then the other half is fastened, the other half is fastened with the crush height of the pair of bearing metals biased to the other side, and as a result, the tightening torque and tightening angle of the bolt used to fasten the other half, i.e., the second bolt, differ significantly depending on whether the bearing metal is located inside the bearing or not.

[0008] The present invention has been made based on the above findings, and is a method for inspecting for missing bearing metals, which determines whether a pair of bearing metals arranged along the inner circumferential surface of a pair of split bearings that support a crankshaft rotatably around an axis along a first direction are attached to the inner circumferential surface of each bearing, and is characterized by comprising: a preparation step of arranging the pair of bearings so that their inner circumferential surfaces face each other across the crankshaft; a tightening step of fastening the pair of bearings to each other using a first bolt and a second bolt located on either side of the axis of the crankshaft in the second direction, where the second bolt is tightened after the first bolt, when a second direction is a direction perpendicular to both the facing direction of the inner circumferential surfaces of the pair of bearings and the first direction; and a determination step of determining whether the bearing metals are attached based on the tightening torque and tightening angle when tightening the second bolt.

[0009] In this method, whether or not a bearing metal is present in the bearing is determined based on the relationship between the tightening torque and tightening angle of the second bolt, which differs significantly depending on whether or not a bearing metal is present, as described above. This allows for accurate detection of missing bearing metal. Furthermore, this method makes the determination based solely on information obtained during the tightening process in which the bearing is tightened with the bolts, eliminating the need to add a new process for detecting missing bearing metal, simplifying the configuration.

[0010] Here, it has been found that the rate of change of the tightening angle relative to the tightening torque of the second bolt differs significantly between when the bearing metal is placed inside the bearing and when it is not.

[0011] Therefore, if the determination process is configured to determine whether the bearing metal is attached or not based on the rate of change of the tightening angle relative to the tightening torque when tightening the second bolt, it is possible to accurately determine whether the bearing metal is missing or not (Claim 2).

[0012] It has also been found that the value obtained by integrating the tightening torque of the second bolt until it reaches a specified torque over the bolt tightening angle differs significantly depending on whether or not the bearing metal is placed inside the bearing.

[0013] Therefore, in the judgment process, if the tightening torque when tightening the second bolt is integrated over the tightening angle of the second bolt until it reaches a predetermined judgment torque, and whether or not the bearing metal is attached is judged based on the obtained integral value, it can be accurately judged whether or not the bearing metal is missing (Claim 3).

[0014] The pair of bearings may include those that constitute the big ends of connecting rods that support the crank pins of the crankshaft (claim 4).

[0015] The present invention also provides a bearing metal missing part inspection device that determines whether a pair of bearing metals, which are arranged along the inner circumferential surfaces of a pair of bearings that support a crankshaft rotatably around an axis that follows a first direction, are attached to the inner circumferential surfaces of each bearing, the device comprising: a fastening device that fastens the pair of bearings, which are arranged so that their inner circumferential surfaces face each other across the crankshaft, using a first bolt and a second bolt located on either side of the crankshaft axis in the second direction, when a second direction is a direction perpendicular to both the opposing direction of the inner circumferential surfaces and the first direction; a detection device that detects the tightening torque and tightening angle of the second bolt; and a control device that controls the fastening device, wherein the control device controls the fastening device so that the second bolt is tightened after the first bolt, and determines whether the bearing metals are attached based on the tightening torque and tightening angle detected by the detection device when the fastening device tightens the second bolt (claim 5).

[0016] As with the above method, this device determines whether or not a bearing metal is missing based on the relationship between the tightening torque and tightening angle of the bolt when the fastening device tightens the bearing with the bolt, making it possible to accurately detect missing bearing metal with a simple configuration. [Effects of the Invention]

[0017] As described above, the bearing metal missing part inspection method and bearing metal missing part inspection device can accurately detect missing bearing metal parts with a simple configuration. [Brief explanation of the drawings]

[0018] [Figure 1] FIG. 2 is a schematic cross-sectional view of the engine body. [Figure 2] FIG. 2 is a schematic plan view of a connecting rod. [Figure 3]1 is a graph showing the relationship between bolt tightening angle and tightening torque. [Figure 4] These are diagrams showing the area around the big end of a connecting rod, where (a) is a diagram when a bearing metal is missing, (b) is a diagram when the crush height of the bearing metal is uniform, and (c) is a diagram when the crush height is biased to one side. [Figure 5] FIG. 1 is a diagram showing the configuration of a bearing metal missing part inspection device. [Figure 6] 10 is a flowchart showing the procedure of a method for inspecting a bearing metal for missing parts. [Figure 7] FIG. 10 is a diagram showing inspection of missing bearing metals. [Figure 8] FIG. 4 is a diagram corresponding to FIG. 3 and is a diagram for explaining a missing item inspection method according to a second embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0019] (1) Crankshaft and connecting rod structure Fig. 1 is a schematic cross-sectional view of an engine body 1 to which a method and device for inspecting missing parts of bearing metals according to a first embodiment of the present invention are applied. Fig. 2 is a schematic plan view of a connecting rod 8, which will be described later.

[0020] The engine body 1 includes a cylinder block 3 and a cylinder head 4. The cylinder block 3 has a plurality of cylinders 2 aligned in the left-right direction in FIG. 1. In the example of FIG. 1, the engine body 1 is an in-line four-cylinder engine, and the cylinder block 3 has four cylinders 2. A piston 5 is housed in each cylinder 2 so that it can reciprocate. Each piston 5 is connected to a crankshaft 7 that extends in the direction in which the cylinders 2 are aligned (the left-right direction in FIG. 1). As each piston 5 reciprocates, the crankshaft 7 rotates around an axis O1 that aligns with the direction in which the cylinders 2 are aligned.

[0021] Each piston 5 and crankshaft 7 are connected via a connecting rod 10. The connecting rod 10 has a shape that extends in a predetermined direction. The crankshaft 7 has a crank journal 71 supported by the cylinder block 3, a crank pin 72, and a crank arm 73 that connects these. The connecting rod 8 is connected to the piston 5 at a small end 11 that constitutes one longitudinal end of the connecting rod 8, and is connected to the crank pin 72 at a big end 12 that constitutes the other longitudinal end of the connecting rod 8.

[0022] The big end 12 has a through hole 12h that penetrates from front to back. The connecting rod 8 is housed in the cylinder block 3 with the central axis O2 of the through hole 12h parallel to the rotational axis O1 of the crankshaft 7. A bearing metal 20 is attached to the entire circumference of the through hole 12h in the big end 12. The crankpin 72 is inserted into the bearing metal 20 and is supported by the big end 12 and bearing metal 20 so that it can rotate relative to the big end 12 and bearing metal 20 about the central axis O2 of the through hole 12h. In the following description of the connecting rod 8, the longitudinal direction will be referred to as the up-down direction, the small end 11 side will be referred to as the lower side, and the big end 12 side will be referred to as the upper side. The direction along the central axis O2 of the through hole 12h in the big end 12, i.e., the direction perpendicular to the plane of the paper in Figure 2, will be referred to as the front-rear direction, and the direction perpendicular to the up-down direction and the front-rear direction, i.e., the left-right direction in Figure 2, will be referred to as the left-right direction. Here, the vertical direction, in which a pair of bearings 12A, 12B (described later) of the big end 12 face each other, corresponds to the "facing direction" in the claims. The front-rear direction, which is the direction along the rotation axis O1 of the crankshaft 7, corresponds to the "first direction" in the claims. The left-right direction corresponds to the "second direction" in the claims. The direction along the central axis O2 of the through hole 12h of the big end 12, which is the central axis O2 of the through hole 12h, and which is the rotational center axis O2 of the crankpin 72 relative to the big end 12 and the bearing metal 20, corresponds to the "axial center of the crankshaft" in the claims.

[0023] As shown in Figure 2, the big end 12 of the connecting rod 8 is made up of a pair of split bearing metals 12A, 12B. The bearing metal 20 is made up of a pair of split bearing metals 20A, 20B. Specifically, the big end 12 of the connecting rod 8 has a first bearing 12A that forms its upper part and has an upwardly convex recessed portion 13A formed on its underside, and a second bearing 12B that forms its lower part and has a downwardly convex recessed portion 13B formed on its upper surface. Each bearing metal 20A has a plate shape that extends in an arc along the inner circumferential surface of each recessed portion 13A, 13B.

[0024] The first bearing 12A and the second bearing 12B are fastened together so that the inner circumferential surfaces of the recesses 13A and 13B face each other and form a cylindrical surface. The first bearing 12A and the second bearing 12B are fastened together so that the bearing metals 20A and 20B extend along the inner circumferential surfaces of the recesses 13A and 13B.

[0025] The big end 12 has bolt holes 14, 15 formed at its right and left ends, at both ends sandwiching the central axis O2 of rotation of the crank pin 72 relative to the big end 12 in the left-right direction. Bolt holes 14A, 14B are formed at the right end of the first bearing 12A and the right end of the second bearing 12B, respectively, into which a common bolt 30 is inserted from above and threaded. Furthermore, bolt holes 15A, 15B are formed at the left end of the first bearing 12A and the left end of the second bearing 12B, respectively, into which a common bolt 30 is inserted from above and threaded. The two bolt holes 14, 15 have the same configuration, and bolts 30 having the same configuration are threaded into these bolt holes 14, 15. The first bearing 12A and the second bearing 12B are fastened to each other by threading bolts 30 into these bolt holes 14, 15, respectively. Hereinafter, the bolt 30 that fastens the first bearing 12A and the second bearing 12B together will be referred to as a connecting rod bolt 30.

[0026] The crank pin 72 is sandwiched between the recess 13A of the first bearing 12A and the recess 13B of the second bearing 12B, and the first bearing 12A and the second bearing 12B are fastened together using the connecting rod bolt 30, whereby the crank pin 72 is connected to and supported by the big end 12 of the connecting rod 8.

[0027] Here, the circumferential length of each of the bearing metals 20A, 20B is set to a dimension longer than the circumferential length of the inner circumferential surface of each of the recesses 13A, 13B. In other words, a crush height (interference) is set for each of the bearing metals 20A, 20B. As a result, when the first bearing 12A and the second bearing 12B are fastened together with two connecting rod bolts 30, each of the bearing metals 20A, 20B expands in diameter and is pressed against the inner circumferential surface of each of the recesses 13A, 13B, and is fixed to these inner circumferential surfaces so as not to rotate relative to each other.

[0028] (2) Principle of bearing metal missing inspection The principle of inspection for missing bearing metals according to the first embodiment will now be described. Fig. 3 is a graph showing the relationship between the tightening angle and tightening torque of the connecting rod bolt 30 when the first bearing 12A and the second bearing 12B are fastened together by the connecting rod bolt 30. Note that the tightening angle in this graph is the tightening angle when tightening of the connecting rod bolt 30 is started from a predetermined value where the vertical separation distance between the first bearing 12A and the second bearing 12B is sufficiently larger than the total dimension of the crush heights of the two bearing metals 20A, 20B.

[0029] Line L1 in Fig. 3 is a graph showing the case where the first bearing 12A and the second bearing 12B are fastened together by the connecting rod bolt 30 without the intervening bearing metal 20, as shown in Fig. 4(a). Specifically, this graph shows the results of investigating the above relationships when two connecting rod bolts 30 are fastened simultaneously. The above relationships for both connecting rod bolts 30 are shown by line L1.

[0030] Line L2 in Figure 3 is a graph showing the results when two connecting rod bolts 30 are simultaneously tightened. Note that when bearing metals 20A, 20B are interposed between first bearing 12A and second bearing 12B, the above relationship for both connecting rod bolts 30 is the relationship shown by line L2.

[0031] Lines L31 and L32 in FIG. 3 are graphs showing the results when one of the two connecting rod bolts 30 is first tightened, and then the remaining connecting rod bolt 30 is tightened, with the bearing metals 20A, 20B interposed between the first bearing 12A and the second bearing 12B. Line L31 shows the results of investigating the above relationship when tightening the first connecting rod bolt 30, and line L32 shows the results of investigating the above relationship when tightening the second connecting rod bolt 30.

[0032] If the bearing metal 20 is not present between the first bearing 12A and the second bearing 12B, the bearing metals 20A, 20B are not tightened. Therefore, in this case, as shown by line L1 in Figure 3, the tightening torque of the connecting rod bolt 30 increases only when the tightening angle becomes relatively large.

[0033] On the other hand, when two connecting rod bolts 30 are simultaneously tightened with the bearing metals 20A, 20B interposed between the first bearing 12A and the second bearing 12B, a substantially equal force is applied to each of the bearings 12A, 12B and the bearing metals 20A, 20B on both sides. Therefore, as shown in Figure 4(b), in this case, the two bearing metals 20A, 20B are positioned symmetrically between the first bearing 12A and the second bearing 12B, that is, the crush heights of the bearing metals 20A, 20B are evenly distributed between the left and right sides. Each connecting rod bolt 30 is tightened while being compressed by approximately half of the sum of the crush heights C1, C2 of the bearing metals 20A, 20B. Therefore, as is clear from a comparison of lines L2 and L1 in FIG. 3, the tightening torque of the connecting rod bolt 30 in this case begins to increase at a timing when the tightening angle is smaller than when there is no bearing metal 20 between the first bearing 12A and the second bearing 12B (hereinafter referred to as the bearing metal missing pattern, as appropriate).

[0034] As a result, when two connecting rod bolts 30 are tightened simultaneously, the increase X2 in the tightening angle until the tightening torque of the connecting rod bolts 30 increases from a predetermined first torque T1 to a larger predetermined second torque T2, i.e., the rate of change X2 of the tightening angle between the first torque T1 and the second torque T2, becomes larger than the increase X1 in the bearing metal shortage pattern.

[0035] In contrast to the above, if one of the left and right connecting rod bolts 30 is first tightened with the bearing metals 20A, 20B interposed between the first bearing 12A and the second bearing 12B, and then the other connecting rod bolt 30 is tightened, force is applied only to one of the left and right sides of the first bearing 12A and the second bearing 12B. As a result, as shown in Figure 4(c), tightening the first connecting rod bolt 30 causes the two bearing metals 20A, 20B to shift to the other side. In other words, the first connecting rod bolt 30 is tightened while causing movement of the bearing metals 20A, 20B, with almost no compression of them. For this reason, as is clear from a comparison of line L31 and line L1 in FIG. 3, the relationship between the tightening angle and tightening torque of the first connecting rod bolt 30 is close to the relationship shown by line L1 when the bearing metals 20A, 20B are not present, and the increase X31 in the tightening angle until the tightening torque of this first connecting rod bolt 30 increases from the first torque T1 to the second torque T2 is slightly larger than the increase X1 in the bearing metal missing pattern and smaller than the increase X2 when two connecting rod bolts 30 are tightened simultaneously.

[0036] On the other hand, the other connecting rod bolt 30 on the left or right, i.e., the second connecting rod bolt 30, is tightened while being compressed by the sum of the crush heights C1 and C2 of the two bearing metals 20A, 20B. For this reason, as is clear from a comparison with lines L2 and L3, if one connecting rod bolt 30 on the left or right is tightened first and then the other connecting rod bolt 30 is tightened, the tightening torque of the second connecting rod bolt 30 will begin to increase at a timing when the tightening angle is even smaller than when the two connecting rod bolts 30 are tightened simultaneously with the bearing metals 20A, 20B interposed between the first bearing 12A and the second bearing 12B.

[0037] As a result, when one of the left and right connecting rod bolts 30 is first tightened and then the other connecting rod bolt 30 is tightened, the increase X32 in the tightening angle until the tightening torque of the second connecting rod bolt 30 increases from the first torque T1 to the second torque T2 is greater than the increase X1 in the bearing metal shortage pattern and the increase X2 in the case where the two connecting rod bolts 30 are tightened simultaneously with the bearing metals 20A, 20B interposed between the first bearing 12A and the second bearing 12B.

[0038] The relationship between the tightening angle and tightening torque of the connecting rod bolt 30 after the connecting rod bolt 30 has been tightened to the position where the bearing metals 20A, 20B abut against each other is the same in all of the above cases.

[0039] As described above, when one of the left and right connecting rod bolts 30 is first tightened and then the other connecting rod bolt 30 is tightened, the relationship between the tightening torque and tightening angle of the second connecting rod bolt 30 is significantly different from the relationship between the tightening torque and tightening angle of the connecting rod bolt 30 in the bearing metal missing pattern. In the first embodiment, this is utilized to inspect for missing bearing metals 20A, 20B.

[0040] (3) Bearing metal missing inspection device and bearing metal missing inspection method FIG. 5 is a schematic diagram showing the configuration of a bearing metal missing part inspection device 100 for inspecting the bearing metal 20 for missing parts.

[0041] The bearing metal missing part inspection device 100 includes a pair of left and right nut runners 102, a control device 104, and an alarm device 106.

[0042] Each nut runner 102 is provided at its tip with a cylindrical socket 110 that can fit onto the head of the connecting rod bolt 30, and a drive unit 112 that rotates the socket 110 to rotate the connecting rod bolt 30 about its central axis. These nut runners 120 thread the connecting rod bolt 30 into the corresponding bolt hole by rotating the socket 110. The nut runners 102 are held by a robot or the like in a state that allows them to move up and down. In this first embodiment, the nut runner 102 is capable of holding a bolt fitted into its socket 110. The nut runner 102 corresponds to the "fastening device" in the claims.

[0043] Each nut runner 102 is provided with an angle sensor SN1 that detects the tightening angle of the connecting rod bolt 30, i.e., the increase in the rotation angle of the connecting rod bolt 30 and the socket 110, and a torque sensor SN2 that detects the tightening torque of the connecting rod bolt 30, i.e., the torque applied to the connecting rod bolt 30 and the socket 110. The angle sensor SN1 and torque sensor SN2 correspond to the "detection device" in the claims.

[0044] The notification device 106 is a device for notifying a worker or the like when the bearing metal 20 (20A, 20B) is missing. The notification device 106 notifies the worker or the like of the missing item by using light or sound.

[0045] The control device 104 controls the drive unit 112 of each nut runner 102 and determines whether or not the bearing metal 20 is missing (whether or not it is attached). The control device 104 has an input / output unit that inputs and outputs signals, and a calculation unit consisting of a CPU or the like that performs calculation processing. The detection values ​​of the angle sensor SN1 and torque sensor SN2 of each nut runner 102 are input to the control device 104. The control device 104 determines whether or not the bearing metal 20 is missing based on these detection values. The control device 104 is electrically connected to the alarm device 106. If the control device 104 determines that the bearing metal 20 is missing, it transmits a predetermined signal to the alarm device 106. Upon receiving this signal, the alarm device 106 notifies the missing part.

[0046] A description will now be given of a method for inspecting for missing bearing metals using the above-described bearing metal missing inspection device 100. Fig. 6 is a flowchart showing the steps of the method for inspecting for missing bearing metals.

[0047] First, the first bearing 12A and the second bearing 12B are arranged so that their inner peripheral surfaces face each other with the crank pin 72 interposed therebetween (step S1).

[0048] In the first embodiment, the second bearing 12B is housed in the cylinder block 3 with the crankpin 72 disposed in the second recess 13B. The cylinder block 3 is oriented so that its bottom surface faces upward, and the portion of the connecting rod 8 from the second bearing 12B to the small end 11 extends downward from the crankpin 72, and the first bearing 12A is disposed and held above the second bearing 12B. The first bearing 12A is also disposed above the second bearing 12B with the inner circumferential surface of its first recess 13A facing downward.

[0049] In the first embodiment, the first bearing 12A is held above the second bearing 12B in the above-mentioned position by the pair of nut runners 102, 102. Specifically, the connecting rod bolts 30 are threaded into the bolt holes 14A, 15A of the first bearing 12A in advance by the nut runners 102, so that the first bearing 12A is held by the nut runners 102 via the connecting rod bolts 30, and the nut runners 102 are then positioned above the first bearing 12A, thereby positioning the first bearing 12A above the second bearing 12B in the above-mentioned position.

[0050] Next, one of the two connecting rod bolts 30 is tightened (step S2). That is, the first connecting rod bolt 30 is tightened. In the example of FIG. 7, the left connecting rod bolt 30 is tightened first. Specifically, the left nut runner 102 is driven by the control device 104. As a result, the left connecting rod bolt 30 is threaded into the left bolt hole 15, fastening the left portions of the first bearing 12A and the second bearing 12B together. Here, this first connecting rod bolt 30, i.e., the connecting rod bolt 30 that is tightened first of the two connecting rod bolts 30, corresponds to the "first bolt" in the claims. Note that the connecting rod bolt 30 that is tightened first may be either the left or right connecting rod bolt 30.

[0051] If the bearing metals 20A, 20B are present between the first bearing 12A and the second bearing 12B, when the first connecting rod bolt 30 is tightened, as shown in FIG. 7 and as described above, the bearing metals 20A, 20B will assume a posture in which the crush heights C1, C2 are biased to one side (to the right in the illustrated example) of the bearing metals.

[0052] Next, the other connecting rod bolt 30 is tightened (step S3). That is, the second connecting rod bolt 30 is tightened. In the example of FIG. 7, the right connecting rod bolt 30 is tightened. Specifically, the right nut runner 102 is driven by the control device 104, thereby fastening the right portions of the first bearing 12A and the second bearing 12B together. Here, this second connecting rod bolt 30, i.e., the connecting rod bolt 30 that is tightened last of the two connecting rod bolts 30, corresponds to the "second bolt" in the claims.

[0053] Next, an angle increment, which is the amount of increase in the tightening angle until the tightening torque of the second connecting rod bolt 30 increases from the first torque T1 to the second torque T2, is calculated (step S4). Specifically, the control device 104 calculates the angle increment based on the detection values ​​of the angle sensor SN1 and torque sensor SN2 of the nut runner 102 (the right nut runner 102 in the example of FIG. 7) that tightens the second connecting rod bolt 30. The first torque T1 and second torque T2 are set in advance and stored in the control device 104.

[0054] Next, it is determined whether the angle increase amount is less than a predetermined determination value (step S5). This determination is made by the control device 104. The determination value is preset to a value greater than the tightening angle increase amount X1 until the tightening torque increases from the first torque T1 to the second torque T2 in the bearing metal shortage pattern, and is stored in the control device 104.

[0055] If this determination is NO and the angle increase is equal to or greater than the determination value, the bearing metals 20A, 20B are correctly positioned between the first bearing 12A and the second bearing 12B, and the process ends (step S8).

[0056] On the other hand, if the above determination is YES and the above angle increase amount is less than the determination value, it means that the bearing metals 20A, 20B are not disposed between the first bearing 12A and the second bearing 12B. In this case, the control device 104 determines that the bearing metals 20A, 20B are missing (step S6) and transmits a predetermined signal to the alarm device 106. In response to this signal, the alarm device 106 notifies that the bearing metals 20A, 20B are missing (step S7).

[0057] Here, the above step S1 corresponds to the "preparation step" in the claims, steps S2 and S3 correspond to the "fastening step" in the claims, and steps S5, S6 and S8 correspond to the "determination step" in the claims.

[0058] (4) Effects, etc. As described above, the bearing metal missing part inspection method and bearing metal missing part inspection device 100 according to the first embodiment utilizes the knowledge that when one of the left and right connecting rod bolts 30 is first tightened and then the other of the left and right connecting rod bolts 30 is tightened, the relationship between the tightening torque and tightening angle of the second connecting rod bolt 30 is significantly different from the relationship between the tightening torque and tightening angle of the connecting rod bolt 30 in the bearing metal missing part pattern. Therefore, one of the left and right connecting rod bolts 30 is tightened first, and then the other of the left and right connecting rod bolts 30 is tightened, and a determination is made as to whether or not a bearing metal 20A, 20B is missing based on the tightening torque and tightening angle of the other of the left and right connecting rod bolts 30, i.e., the second connecting rod bolt 30, and this makes it possible to accurately detect missing parts.

[0059] Moreover, with the configuration according to the first embodiment, the above determination can be made based only on information obtained in the fastening process of fastening the first bearing 12A and the second bearing 12B with the connecting rod bolt 30. Therefore, there is no need to add new processes or devices for the above determination, that is, for detecting missing bearing metals 20A, 20B, and the configuration can be simplified.

[0060] In particular, in the above embodiment, the above determination is made based on the rate of change of the tightening angle with respect to the tightening torque of the second connecting rod bolt 30 when one of the left and right connecting rod bolts 30 is first tightened and then the other connecting rod bolt 30 is tightened; specifically, the increase in the tightening angle until the tightening torque increases from the first torque T1 to the second torque T2; and when the bearing metals 20A, 20B are located between the first bearing 12A and the second bearing 12B, this parameter has a value that is significantly larger than that of the bearing metal missing pattern, making it possible to detect missing bearing metals 20A, 20B with greater accuracy.

[0061] (5) Second embodiment Next, a bearing metal missing part inspection method according to a second embodiment will be described. Fig. 8 is a graph showing the relationship between the tightening angle and tightening torque of the connecting rod bolt 30, similar to Fig. 3. However, Fig. 8 shows only line L1 and line L32 out of the lines shown in Fig. 3.

[0062] 8, in the graph of tightening angle and tightening torque, the area A3 of the region surrounded by line L32 and line L200 that passes through the tightening angle θ10 when the tightening torque reaches the predetermined torque T10 is significantly different from the area A1 of the region surrounded by line L1 and line L200. Thus, in the second embodiment, the control device 104 determines whether or not the bearing metals 20A, 20B are missing based on this area, that is, the integral of the tightening torque with respect to the tightening angle until the tightening torque reaches the predetermined torque T10.

[0063] Specifically, in the second embodiment, instead of step S4 in the first embodiment, the control device 104 performs a step of integrating the tightening torque of the second connecting rod bolt 30 until the tightening torque reaches a predetermined judgment torque T10, with respect to the tightening angle of the connecting rod bolt 30. The integral value obtained in this step will be referred to as the tightening torque integral value below. Next, in the second embodiment, instead of step S5 in the first embodiment, the control device 104 performs a step of determining whether the tightening torque integral value is less than a predetermined judgment integral value. The judgment integral value is preset to a value greater than the tightening torque integral value in the bearing metal missing pattern and stored in the control device 104. Furthermore, the judgment torque T10 is preset to a value greater than 0, at which a clear difference occurs between the tightening torque integral value in the bearing metal missing pattern and other patterns, and is stored in the control device 104.

[0064] The subsequent steps are the same as in the first embodiment, and if the above determination is NO and the tightening torque integral value is equal to or greater than the determination integral value, it is determined that the bearing metals 20A, 20B are correctly positioned between the first bearing 12A and the second bearing 12B, and the processing is terminated. On the other hand, if the above determination is NO and the tightening torque integral value is less than the determination integral value, the control device 104 determines that the bearing metals 20A, 20B are not positioned between the first bearing 12A and the second bearing 12B, that is, that the bearing metals 20A, 20B are missing, and sends a predetermined signal to the alarm device 106. Upon receiving this signal, the alarm device 106 notifies that the bearing metals 20A, 20B are missing. In the second embodiment, too, the first connecting rod bolt 30, i.e., the connecting rod bolt 30 that is tightened first of the two connecting rod bolts 30, corresponds to the "first bolt" in the claims, and the second connecting rod bolt 30, i.e., the connecting rod bolt 30 that is tightened last of the two connecting rod bolts 30, corresponds to the "second bolt" in the claims. Also, in the second embodiment, the connecting rod bolt 30 that is tightened first may be either the left or right connecting rod bolt 30.

[0065] As described above, in the second embodiment as well, the determination of whether or not the bearing metals 20A, 20B are missing is based on a parameter that is the integral of the tightening torque with respect to the tightening angle of the second connecting rod bolt 30 when one of the left and right connecting rod bolts 30 is first tightened and then the other connecting rod bolt 30 is tightened, and that has a value that is significantly larger when the bearing metals 20A, 20B are disposed between the first bearing 12A and the second bearing 12B than in the bearing metal missing pattern, making it possible to accurately detect whether or not the bearing metals 20A, 20B are missing.

[0066] (6) Variations In the above embodiment, the above configuration was described as being applied to determining whether bearing metals 20A, 20B are attached between first bearing 12A and second bearing 12B that constitute big end 12 of connecting rod 8. However, the above configuration may also be applied to other bearings that rotatably support crankshaft 7. For example, crank journal 71 of crankshaft 6 is rotatably supported by journal bearing 9 provided in cylinder block 3 and bearing metal 40 attached to its inner circumferential surface. Therefore, the above configuration may be applied to determining whether bearing metal 40 is attached inside journal bearing 9. However, when multiple journal bearings 9 are integrally provided in cylinder block 3 as shown in FIG. 1 , the relationship between the tightening angle and tightening torque of each bolt that fastens journal bearing 9 is easily affected by the state of the other journal bearings 9, making it difficult to determine whether bearing metal 40 is missing based on this relationship. Therefore, the above configuration is preferably applied to engines in which journal bearings 9 are independent, i.e., engines that are not integrally formed with other journal bearings 9. [Explanation of symbols]

[0067] 7. Crankshaft 8 Connecting rods 12 Big end 12A No. 1 bearing (bearing) 12B Second bearing (bearing) 20 Bearing metal 20A bearing metal 20B bearing metal 30 Connecting rod bolt (bolt) 72 Crank pin 100 Missing Item Inspection Device 102 Nut runner (fastening device) 104 Control device

Claims

1. A method for inspecting for missing bearing metals, the method determining whether a pair of bearing metals disposed along inner peripheral surfaces of a pair of half-shaped bearings that support a crankshaft rotatably around an axis along a first direction are attached to inner peripheral surfaces of the pair of half-shaped bearings, the bearings comprising: a preparation step of arranging the pair of bearings so that their inner circumferential surfaces face each other across the crankshaft; a fastening process for fastening the pair of bearings to each other using first bolts and second bolts located on opposite sides of the crankshaft axis in the second direction, where a direction perpendicular to both the opposing direction of the inner circumferential surfaces of the pair of bearings and the first direction is defined as a second direction, and the second bolts are fastened after the first bolts. and a determination step of determining whether the bearing metal is attached or not based on the tightening torque and tightening angle when tightening the second bolt.

2. 2. The method for inspecting a bearing metal for missing parts according to claim 1, A method for inspecting for missing bearing metals, characterized in that in the judgment process, it is determined whether the bearing metal is attached or not based on the rate of change of the tightening angle relative to the tightening torque when tightening the second bolt.

3. 2. The method for inspecting a bearing metal for missing parts according to claim 1, In the judgment step, the tightening torque when tightening the second bolt until it reaches a predetermined judgment torque is integrated with respect to the tightening angle of the second bolt, and whether or not the bearing metal is attached is judged based on the obtained integral value.

4. The method for inspecting a bearing metal for missing parts according to any one of claims 1 to 3, A method for inspecting for missing bearing metals, wherein the pair of bearings constitute the big end of a connecting rod that supports the crank pin of the crankshaft.

5. A bearing metal missing inspection device that determines whether a pair of bearing metals, which are disposed along inner peripheral surfaces of a pair of bearings that support a crankshaft rotatably around an axis along a first direction, are attached to inner peripheral surfaces of the pair of bearings, the pair of bearings comprising: a fastening device that fastens the pair of bearings, each of which has an inner circumferential surface facing each other across the crankshaft, to each other using a first bolt and a second bolt located on either side of the crankshaft axis in the second direction, when a direction perpendicular to both the opposing direction of the inner circumferential surfaces and the first direction is defined as a second direction; a detection device for detecting the tightening torque and tightening angle of the second bolt; a control device for controlling the fastening device, The control device controls the fastening device so that the second bolt is tightened after the first bolt, and determines whether the bearing metal is attached based on the tightening torque and tightening angle detected by the detection device when the fastening device tightens the second bolt.

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