A method for detecting the phase angle of a crankshaft connecting rod journal

Abstract

The present application relates to a kind of detection crankshaft connecting rod journal phase angle measurement method, belong to crankshaft connecting rod journal phase angle measurement technical field.It includes the following steps: step one, make the alignment of crankshaft reference;Step two, complete 1 / 2 crankshaft stroke (1 / 2S) measurement;Step three, complete the determination of combination gauge block and the establishment of reference cylinder connecting rod journal 0 ° measurement reference;Step four, complete the calculation of theoretical height K;Step five, complete the measurement and calculation of the center height of the connecting rod shaft of each remaining cylinder;Step six, complete the measurement of the connecting rod journal phase angle of each remaining cylinder.The present application takes one of the crankshaft connecting rods of cylinder as reference, and accurately measures the connecting rod journal phase angle of other cylinders, and the data is accurate and reliable.

Description

Technical Field

[0001] This invention belongs to the field of crankshaft connecting rod journal phase angle measurement technology, specifically relating to a method for measuring the phase angle of crankshaft connecting rod journals. Background Technology

[0002] The crankshaft is one of the most important components of a diesel engine. Besides converting the reciprocating motion of the piston into rotational motion and outputting power, it also drives the valve train, fuel injection pump, lubrication pump, and cooling water pump, among other accessories. Its importance is self-evident. Taking the crankshaft of the 8-cylinder diesel engine LB8250 as an example, its structure is an integral type, consisting of a free end, a flywheel end (power output end), and several cranks. The cranks are arranged in a row. Each crank (unit crank) consists of two main journals, one connecting rod journal, and two crank arms. Starting from the flywheel end, the first crank is called the first crank, and so on, from the second to the third crank…

[0003] During the operation of a diesel engine, the crankshaft is subjected to periodically changing gas pressure, reciprocating and rotating mass inertia forces, and the torques formed by these forces, transmitted from the piston and connecting rod. Therefore, to ensure the reliability and smooth operation of the diesel engine, the firing intervals of each cylinder must be uniform, meaning the connecting rod journal phase angles φ of the crankshaft must be equal. In one working cycle (intake, compression, power, and exhaust) of an eight-cylinder diesel engine, the crankshaft rotates twice (720°). To ensure uniform firing in each cylinder, the firing interval angle is: ψ = 720° / 8 = 90°. Since the crankshaft cranks of the LB8250 diesel engine are arranged in pairs, meaning two cylinder cranks overlap, the firing interval angle ψ is equal to the connecting rod journal phase angle φ on the crankshaft end face. Therefore, the connecting rod journal phase angle φ conforms to: φ = 720° / 8 = 90° (see details). Figure 1 Show).

[0004] The crankshaft connecting rod journal phase angle φ is one of the important parameters of a diesel engine. Changes in the magnitude of the connecting rod journal phase angle φ will inevitably affect changes in the firing interval angle ψ and crankshaft rotation angle θ, thereby affecting various performance parameters of the diesel engine during operation. Therefore, it is very important to ensure that the crankshaft connecting rod journal phase angle φ is within the technical requirements.

[0005] The inspection of the phase angle φ of the crankshaft connecting rod journal is a difficult and important aspect of crankshaft inspection. For many years, there has been no good method to inspect it or to evaluate and analyze the uncertainty of its inspection results. The application of this crankshaft connecting rod journal phase angle measurement method can complete the detection of the phase angle φ of each connecting rod journal of the crankshaft, thereby helping to further improve the crankshaft machining quality. Summary of the Invention

[0006] The technical problem to be solved by the present invention is to overcome the shortcomings of the prior art and provide a method for measuring the phase angle of the crankshaft connecting rod journal. The present invention uses the crankshaft connecting rod of one cylinder as a reference to successively and accurately measure the phase angle of the crankshaft connecting rod journal of other cylinders, and the data is accurate and reliable.

[0007] The technical solution adopted by this invention to solve the problems existing in the prior art is:

[0008] A method for measuring the phase angle of a crankshaft connecting rod journal includes the following steps:

[0009] Step 1: Align the crankshaft reference.

[0010] Step 2: Complete the measurement of 1 / 2 crankshaft stroke (1 / 2S);

[0011] Step 3: Complete the determination of the combined gauge blocks and establish the 0° measurement datum for the reference cylinder connecting rod journal;

[0012] Step 4: Complete the calculation of the theoretical height K;

[0013] Step 5: Complete the measurement and calculation of the center height of the connecting rod shafts of the remaining cylinders;

[0014] Step 6: Complete the measurement of the phase angle of the connecting rod journals of the remaining cylinders.

[0015] Preferably, in step one, the crankshaft is suspended on the adjustable V-shaped rollers on the testing platform, and a height gauge is attached to a lever dial indicator to measure the upper generatrix of each main journal of the crankshaft.

[0016] By adjusting the adjustable V-rollers, the parallelism tolerance between the crankshaft main journal centerline and the platform is less than 0.01mm, and the circular runout error of each main journal is less than 0.01mm. Then the installation and adjustment of the crankshaft is complete.

[0017] Preferably, in step two, the main journal dimension is measured as φE, the crank pin dimension as ΦF, and the height of the upper generatrix of the main journal is measured as a using a height gauge lever dial indicator. Then, the crankshaft is rotated to bring the connecting rod journal to top dead center, and the upper generatrix of the connecting rod journal is measured as b. Therefore, the 1 / 2 crankshaft stroke (1 / 2S) is:

[0018] 1 / 2S = bF / 2 - a + E / 2.

[0019] Preferably, in step three, during the measurement of the crankshaft connecting rod journal phase angle, the line OA' connecting the centerline A' of a certain cylinder connecting rod journal and the common centerline O of the main journal is used as the 0° measurement reference. When the axis A of the reference cylinder connecting rod journal and the common axis O of the main journal are horizontal, the upper generatrix height c of the reference cylinder connecting rod journal is:

[0020] c = aE / 2 + F / 2

[0021] At this point, the reference cylinder connecting rod journal is rotated clockwise by the theoretically correct angle of 45° to A'. The vertical distance A'B that the center of the reference cylinder connecting rod journal descends is then:

[0022] A'B=sin45°×OA'=sin45°×1 / 2S

[0023] The distance *m* between the zero point of the height gauge lever dial indicator and the dedicated inspection platform has been measured. Therefore, the distance *h* between the lower generatrix of the reference cylinder connecting rod journal and the platform is:

[0024] h = cF - A'B – m.

[0025] Preferably, the gauge block is placed on the lower generatrix of the reference cylinder connecting rod journal, and the crankshaft is fixed. Then, the line OA' connecting the center line A' of the reference cylinder connecting rod journal and the common center line O of the main journal is used as the 0° measurement reference. The phase angles of the remaining cylinder connecting rod journals are obtained by comparing them with the reference OA'.

[0026] Then the height of point A' = h + F / 2 + m.

[0027] Preferably, during the measurement of the crankshaft connecting rod journal phase angle, the last cylinder is used as the reference cylinder, and the line OA' connecting the center line A' of the connecting rod journal of the last cylinder and the common center line O of the main journal is used as the 0° measurement reference.

[0028] Preferably, in step four, the height of point K = the height of point A' + A'B × 2

[0029] The height of the connecting rod journal centerline of each of the remaining cylinders is measured using the correct theoretical height of point K as the reference. For heights greater than, equal to, or less than the height of point K, trigonometric functions are used to calculate the phase angle of each cylinder.

[0030] Preferably, in step five, the height of the upper generatrix of each remaining connecting rod journal is measured using a height gauge lever dial indicator. Then, the center height of each cylinder connecting rod journal is the upper generatrix height of each cylinder connecting rod journal minus 1 / 2F (199.98 / 2).

[0031] Preferably, in step six, the center height of the connecting rod journal of one of the cylinders other than the reference cylinder is D.

[0032] Given that the height of the upper generatrix of the main journal is 'a', then the height of point F is:

[0033] The height of point F = a - 1 / 2E - 1 / 2S

[0034] Then EF is: EF = height of point D - height of point F

[0035] Therefore, OE is: OE = OF - EF = 1 / 2S - EF

[0036] Then: cosβ=OE / OD, and we can find angle β.

[0037] The phase angle (clockwise) of the connecting rod journal of the first cylinder relative to the connecting rod journal of the reference cylinder is: 0°+β.

[0038] Preferably, after measuring the phase angle of the connecting rod journal of the remaining cylinders, the measured phase angle results are calculated according to the firing order of the diesel engine.

[0039] Compared with the prior art, the present invention has the following beneficial effects:

[0040] This invention mainly uses the line OA' connecting the center line A' of the reference cylinder connecting rod journal and the common center line O of the main journal as the 0° measurement reference. It also employs precise calculation using trigonometric functions and precise positioning of combined gauge blocks to complete the detection of the phase angle of each connecting rod journal of the crankshaft. The detection process and measurement results conform to the closure principle and Abbe principle among the four major measurement principles. Attached Figure Description

[0041] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0042] Figure 1 This is a schematic diagram of the phase angles of each connecting rod journal of the LB8250ZLC eight-cylinder diesel engine (right-hand drive, right-hand rotation).

[0043] Figure 2 This is a schematic diagram for measuring the phase angle of the connecting rod journal of an eight-cylinder crankshaft.

[0044] Figure 3 To determine OA' as the 0° measurement reference map,

[0045] Figure 4 This is a measurement diagram of the crankshaft phase angle of the first gear connecting rod.

[0046] Figure 5 To determine the theoretical height K value of the connecting rod journal centerline for cylinders 4, 5, 3, and 6,

[0047] Figure 6 This is a measurement diagram of the relative angle of the connecting rod journal of cylinder 4.

[0048] Figure 7 This is a step diagram of a method for measuring the phase angle of a crankshaft connecting rod journal according to the present invention. Detailed Implementation

[0049] The specification and claims use certain terms to refer to specific components. Those skilled in the art will understand that hardware manufacturers may use different names to refer to the same component. This specification and claims do not distinguish components based on differences in name, but rather on differences in function. The term "comprising" throughout the specification and claims is an open-ended term and should be interpreted as "comprising but not limited to." "Approximately" means that within an acceptable margin of error, those skilled in the art can solve the technical problem and substantially achieve the technical effect within a certain margin of error.

[0050] In the description of this invention, it should be understood that the terms "upper", "lower", "front", "rear", "left", "right", "horizontal", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0051] In this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0052] The following detailed description of a method for measuring the phase angle of a crankshaft connecting rod journal, in conjunction with the accompanying drawings, is not intended to limit the scope of the invention.

[0053] To facilitate understanding, this embodiment uses the detection method of the 90° phase angle of the crankshaft connecting rod journal of an 8-cylinder diesel engine LB8250ZLC (right-hand engine, right-hand rotation) as an example, and includes specific numerical values ​​in the formula to explain the method.

[0054] A specific method for measuring the phase angle of a crankshaft connecting rod journal includes the following steps:

[0055] Step 1: Alignment of the crankshaft reference:

[0056] On a Level 3 dedicated testing platform (platform dimensions: 1600mm × 6000mm), wipe the crankshaft and platform clean with a towel. Suspend the crankshaft onto the dedicated adjustable V-rollers on the platform (the V-rollers are supported on the 1st, 4th, and 7th main journals; inject an appropriate amount of lubricating oil into the contact surface between the V-rollers and the crankshaft). Simultaneously, attach a dial indicator to the height gauge. Figure 2After (shown), measure the upper generatrix of each main journal of the crankshaft (at this time, the zero position of the lever dial indicator is the maximum feedback point of the indicator needle). By adjusting the adjustable V-roller, make the parallelism tolerance between the center line of the main journal of the crankshaft and the platform less than 0.01mm, and the circular runout error of each main journal less than 0.01mm. Then the installation and adjustment of the crankshaft is completed.

[0057] Step 2: Measurement of 1 / 2 crankshaft stroke (1 / 2S):

[0058] The main journal dimension has been measured to be φE (φ219.98mm) and the crank pin dimension is ΦF (φ

[0059] The height of the upper generatrix of the main journal, measured using a height gauge lever and dial indicator, is: a = 654.94 mm (199.98 mm). Figure 2 (See diagram), then rotate the crankshaft until the connecting rod journal is at top dead center (Note: at top dead center, the pointer of the dial indicator is at zero, which is the maximum feedback point of the pointer). At this time, the generatrix of the connecting rod journal is measured as: b = 804.95 mm. Figure 2 (as shown), then 1 / 2 crankshaft stroke (1 / 2S) is:

[0060] 1 / 2S = bF / 2 - a + E / 2

[0061] 1 / 2S=804.95-199.98 / 2-654.94+

[0062] 219.98 / 2

[0063] 1 / 2S = 160.01 (mm)

[0064] That is, the 1 / 2 crankshaft stroke (1 / 2S) is 160.01 (mm).

[0065] Step 3: Determine the dimensions of the assembled gauge block h:

[0066] During the measurement of the crankshaft connecting rod journal phase angle, the line OA' connecting the center line A' of the 8th cylinder connecting rod journal and the common center line O of the main journal is used as the 0° measurement reference (e.g., Figure 2 or Figure 3 (As shown), when the axis A of the connecting rod journal of the 8th cylinder is horizontal with the common axis O of the main journal (e.g.) Figure 2 or Figure 3 (As shown), the upper generatrix height c of the connecting rod journal of cylinder 8 is:

[0067] c = aE / 2 + F / 2

[0068] c = 654.94 - 219.98 / 2 + 199.98 / 2

[0069] = 644.94 (mm)

[0070] At this point, rotate the connecting rod journal of cylinder 8 clockwise from the horizontal direction by the theoretically correct angle of 45° to A' (e.g., Figure 2 or Figure 3 (As shown), the vertical distance A'B that the center of the connecting rod journal of cylinder 8 descends is:

[0071] A'B = sin45° × OA'

[0072] =sin45°×1 / 2S=sin45°×160.01

[0073] = 113.1442 (mm)

[0074] The distance m between the zero point of the height gauge lever dial indicator and the special inspection platform has been measured to be: m = 34.46 (mm). Then, the distance h between the lower generatrix of the connecting rod journal of the 8th cylinder and the platform at this time is... Figure 2 (Shown) as:

[0075] h = cF - A'B – m

[0076] =644.94 - 199.98 - 113.1442 - 34.46

[0077] =297.3558 (mm)

[0078] Step 4: Complete the assembly of gauge block h and determine the 0° reference for measurement:

[0079] The gauge block h = 297.3558 mm is composed of five gauge blocks with the following dimensions: 200, 90, 5, 1.35, and 1.005 mm. After grinding the five gauge blocks together, place them on the lower generatrix of the connecting rod journal of cylinder 8. Figure 2 (See diagram), and fix the crankshaft. Then, take the line OA' connecting the center line A' of the 8th cylinder connecting rod journal and the common center line O of the main journal as the 0° measurement reference. The remaining cylinders 1 to 7...

[0080] The phase angles of the rod journals are all compared with the reference OA'.

[0081] And that's what we got.

[0082] Then the height of point A' = h + F / 2 + m

[0083] =297.3558 + 199.98 / 2 + 34.46

[0084] = 431.8058 (mm)

[0085] At this point, the height of point A', the center line of the connecting rod journal of cylinder 8, is the height reference for phase angle measurement, i.e., the 0° reference. The heights of the center lines of the connecting rod journals of cylinders 1, 2, and 7 are all measured with the height of point A', the center line of the connecting rod journal of cylinder 8, as the height reference. If the height is greater than, equal to, or less than the height of point A', trigonometric function calculations are performed to complete the measurement of the phase angle of each cylinder.

[0086] Step 5: Determine the correct theoretical height K of the connecting rod journal centerline for cylinders 4, 5, 3, and 6. Figure 5 As shown):

[0087] The theoretical height K of the center line of the connecting rod journal of cylinders 4, 5, 3, and 6 is at the intersection of the extension of A'O (which conforms to Abbe's principle) and the rotation center line of the connecting rod journal.

[0088] The height of point K = the height of point A' + A'B × 2

[0089] =431.8085 + 113.1442 × 2

[0090] = 658.0969 (mm)

[0091] The centerline height of the connecting rod journals of cylinders 4, 5, 3, and 6 is measured using the correct theoretical height at point K as the reference. For heights greater than, equal to, or less than the height at point K, trigonometric functions are used to calculate the phase angle of each cylinder.

[0092] The correct theoretical height of point K conforms to Abbe's principle, one of the four fundamental principles of measurement.

[0093] Step Six: Complete the measurement and calculation of the center height of the journals of connecting rods 1 through 7:

[0094] The height of the upper generatrix of the journals of the remaining connecting rods 1 through 7 was measured using a height gauge, lever, and dial indicator. The results are as follows:

[0095] Table 1 shows:

[0096] Cylinder 2 530.74 Cylinder 7 530.60 Cylinder 6 760.36 Cylinder 3 760.35 Cylinder 4 757.12 Cylinder 5 757.10

[0097] Table 1

[0098] The center height of each cylinder connecting rod journal is the height of the upper generatrix of each cylinder connecting rod journal minus 1 / 2F (199.98 / 2), as shown in Table 2 below:

[0099]

[0100]

[0101] Table 2

[0102] Step 7: Complete the measurement of the phase angle of the connecting rod journal of cylinder 1. Figure 4(as shown) and measurements of the phase angles of the connecting rod journals of cylinders 2 and 7:

[0103] The height of the connecting rod journal centerline of cylinders 1, 2, and 7 is measured using the height of point A' on the connecting rod journal centerline of cylinder 8 as the reference. Trigonometric functions are used to calculate the phase angle of each cylinder if the height is greater than, equal to, or less than the height of point A'.

[0104] The height of the center D of the connecting rod journal of cylinder 1 is 431.75 mm (as shown in Table 2), and the height of point A' is 431.8085 mm; 431.75 < 431.8058, that is, the height of point D is less than the height of point A', therefore point D is below point A'. Figure 4 Show).

[0105] Given that the height of the upper generatrix of the main journal is: a = 654.94 mm ( Figure 2 (as shown), then the height of point F is:

[0106] The height of point F = a - 1 / 2E - 1 / 2S = 654.94 - 219.98 / 2 - 160.01 = 384.94 (mm)

[0107] Therefore, EF is: EF = Height of point D - Height of point F = 431.75 - 384.94 = 46.81 (mm)

[0108] Therefore, OE is: OE = OF - EF = 1 / 2S - EF = 160.01 - 46.81 = 113.20 (mm)

[0109] Therefore: cosβ=OE / OD=113.20 / 160.01

[0110] β=44.97°=44°58'36”

[0111] Therefore: 45° - 44°58'36" = 1'24"

[0112] The phase angle (clockwise) between the first cylinder connecting rod journal and the eighth connecting rod journal is: 0° + 1'24".

[0113] Using the same method, the phase angles (clockwise) of the connecting rod journals of cylinders 2 and 7 relative to the connecting rod journal of cylinder 8 can be detected as: 90°-32'14"; 90°-36'32".

[0114] Step 8: Complete the measurement of the phase angle of the connecting rod journal of cylinder 4. Figure 6 (As shown) and measurements of the connecting rod journal phase angles for cylinders 5, 3, and 6:

[0115] The centerline height of the connecting rod journals of cylinders 4, 5, 3, and 6 is based on the correct theoretical height at point K. Figure 5 (As shown) The height reference is used for measurement. Trigonometric function calculations are performed for heights greater than, equal to or less than the height of point K to complete the measurement of the phase angle of each cylinder.

[0116] Given the theoretical center height of point K ( Figure 5 The height of the connecting rod journal center point H (shown in Table 2) is 658.0969 (mm). Since 657.13 < 658.0969, point H is below the theoretical center height K. When measuring the stroke, the top dead center height of the connecting rod journal is known to be: b = 804.95 mm. Figure 2 (As shown), then the height of point L = bF / 2 = 804.95 - 199.98 / 2 = 704.96 (mm)

[0117] Therefore, LM = 704.96 - the height of point H = 704.96 - 657.13 = 47.83 (mm)

[0118] Therefore, OM = OL - LM = 160.01 - 47.83 = 112.18 (mm)

[0119] cosα=OM / OH=112.18 / 160.01

[0120] α = 45.48° = 45°29'10"

[0121] Then 225°-45°29'10”=180°-29'10”.

[0122] The phase angle (clockwise) of the connecting rod journal of cylinder 4 relative to the connecting rod journal of cylinder 8 is 180°-29'10". Similarly, the phase angles (clockwise) of the connecting rod journals of cylinders 5, 3 and 6 relative to the connecting rod journal of cylinder 8 can be detected, which are 180°-29'46", 270°-44'15", and 270°-44'34", respectively.

[0123] Measured results (shown in Table 3) and uncertainty assessment of measurement results:

[0124] We have compiled the measured phase angle data of each cylinder connecting rod journal into a table (as shown in Table 3).

[0125] According to the test run outline, the firing order of the LB8250ZLC (right-hand engine, right-turn) diesel engine is: 1, 3, 5, 7, 8, 6, 4, 2. We then calculated the phase angles of each connecting rod journal (1st and 3rd, 3rd and 5th, 7th and 8th, 8th and 6th, 6th and 4th, 4th and 2nd, and 2nd and 1st) according to the firing order of the diesel engine (as shown in Table 4). From this, we can see that the phase angles of the connecting rod journals at 3rd and 5th, 5th and 7th, and 4th and 2nd are within the technical requirements, while the phase angles of the connecting rod journals at 1st and 3rd, 7th and 8th, 8th and 6th, 6th and 4th, and 2nd and 1st are all outside the technical requirements.

[0126] Meanwhile, after summing up the phase angle errors of all connecting rod journals in Table 4, the detection result will inevitably be equal to zero (45'39"-14'29"+6'46"-36'32"+44'34"-15'24"+3'4"-33'38"=0). Therefore, this measurement method conforms to the closure principle, one of the four major measurement principles, indicating that the measurement method is correct, reasonable and effective.

[0127]

[0128]

[0129] Table 3

[0130]

[0131] Table 4

[0132] The measurement accuracy error rate η of this method is within 5%, therefore the data obtained by this method is valid, as detailed below:

[0133] In this embodiment, we take the detection method of the 90° phase angle of the crankshaft connecting rod journal of the LB8250ZLC (right-hand engine, right-hand rotation) 8-cylinder diesel engine as an example, and then extend it to the detection of the phase angle of the crankshaft connecting rod journal of other diesel engines with any number of cylinders. The above measurement method, due to the use of precise calculation and precise positioning of gauge blocks, uses the 8th cylinder connecting rod journal as the measurement reference, ensuring accuracy. In actual testing, we can use any cylinder connecting rod journal as the measurement reference to verify the effectiveness of this method. However, there will still be some measurement error during the measurement process, which can be analyzed from the following aspects:

[0134] 1. The lever micrometer has an accuracy of 0.002mm, and the error generated during the measurement process is: Δ1=0.002mm.

[0135] 2. The crankshaft main journal circular runout tolerance is less than 0.02mm, and the measurement error during inspection is approximately: Δ2≈0.02mm.

[0136] 3. The parallelism error between the crankshaft main journal centerline and the platform is approximately: Δ3≈0.01mm.

[0137] 4. When the zero point is being aligned with the maximum feedback point during actual measurement, the measurement error during testing is: Δ4 = 0.001 mm.

[0138] 5. Errors caused by factors such as flatness of the measuring platform are negligible.

[0139] 6. Random error Δ is introduced during measurement due to variations in temperature, lubrication conditions, reading errors, etc. Random error can be reduced by improving measurement conditions and using the average of multiple measurements. The confidence probability of the random error calculated by the following formula is 95%.

[0140]

[0141] In the formula:

[0142] x i : The reading error of the i-th measurement.

[0143] The average of the reading errors of the nth measurement.

[0144] n: Number of measurements

[0145] Given the above errors, the total measurement error is:

[0146]

[0147] sinλ=0.025 / 160.01

[0148] λ=0.00895°=0°0'32”

[0149] That is, the phase angle error λ generated during the measurement process is:

[0150] λ=0°0'32”

[0151] According to technical requirements, the phase angle of the connecting rod journal of cylinder 8 is φ = 90° ± 15'. Figure 1 (As shown), the total error of its phase angle is 30', that is, 0°30'0".

[0152] Therefore, the measurement accuracy error rate η is:

[0153]

[0154] η = 1.7%

[0155] From the above analysis, we know that the accuracy error rate of phase angle measurement during the detection process is η = 1.7%.

[0156] Generally, the measurement accuracy error rate is required to be controlled within 5%. The measurement accuracy error rate of the 90° phase angle of the crankshaft connecting rod journal of this 8-cylinder diesel engine is within the required range. Therefore, although the above measurement method has a certain measurement error, it is controlled within a reasonable and effective range and is acceptable. This also reflects that the data of the crankshaft connecting rod journal phase angle measured by the measurement method of the present invention is reliable.

[0157] The embodiments of the present invention have been described in detail above with reference to the accompanying drawings. However, the present invention is not limited to the above embodiments. Within the scope of knowledge possessed by those skilled in the art, various changes can be made without departing from the spirit of the present invention.

Claims

1. A method for measuring the phase angle of a crankshaft connecting rod journal, characterized in that, Includes the following steps: Step 1: Align the crankshaft reference. Step 2: Complete the measurement of 1 / 2 crankshaft stroke (1 / 2S); The measured dimensions of the main journal are: φE, the crank pin dimensions are: ΦF, and the height of the upper generatrix of the main journal is: a, measured using a height gauge lever dial indicator. Step 3: Complete the determination of the combined gauge blocks and establish the 0° measurement datum for the reference cylinder connecting rod journal; During the measurement of the crankshaft connecting rod journal phase angle, the line OA' connecting the centerline A' of a certain cylinder connecting rod journal and the common centerline O of the main journal is used as the 0º measurement reference. When the axis A of the reference cylinder connecting rod journal and the common axis O of the main journal are horizontal, the upper generatrix height c of the reference cylinder connecting rod journal is: c = aE / 2 + F / 2 At this point, the reference cylinder connecting rod journal is rotated clockwise by the theoretically correct angle of 45º to A'. The vertical distance A'B that the center of the reference cylinder connecting rod journal descends is then: A'B=sin45º×OA'=sin45º×1 / 2S The distance *m* between the zero point of the height gauge lever dial indicator and the dedicated inspection platform has been measured. Therefore, the distance *h* between the lower generatrix of the reference cylinder connecting rod journal and the platform is: h = cF - A'B –m; The gauge block is placed on the lower generatrix of the reference cylinder connecting rod journal, and the crankshaft is fixed. The line OA' connecting the center line A' of the reference cylinder connecting rod journal and the common center line O of the main journal is used as the 0º measurement reference. The phase angles of the remaining cylinder connecting rod journals are obtained by comparing them with the reference OA'. Then the height of point A' = h + F / 2 + m; During the measurement of the crankshaft connecting rod journal phase angle, the last cylinder is used as the reference cylinder, and the line OA' connecting the center line A' of the connecting rod journal of the last cylinder and the common center line O of the main journal is used as the 0º measurement reference. Step 4: Complete the calculation of the theoretical height K. The theoretical height K is located at the intersection of the extension line of A'O and the rotation center line of the connecting rod journal. Step 5: Complete the measurement and calculation of the center height of the connecting rod shafts of the remaining cylinders; Step 6: Complete the measurement of the phase angle of the connecting rod journals of the remaining cylinders.

2. The method for measuring the phase angle of a crankshaft connecting rod journal according to claim 1, characterized in that: In step one, the crankshaft is suspended on the adjustable V-rollers of the testing platform. Simultaneously, a height gauge with a lever dial indicator is attached, and the upper generatrix of each main journal of the crankshaft is measured. By adjusting the adjustable V-rollers, the parallelism tolerance between the crankshaft main journal centerline and the platform is less than 0.01mm, and the circular runout error of each main journal is less than 0.01mm. Then the installation and adjustment of the crankshaft is complete.

3. The method for measuring the phase angle of a crankshaft connecting rod journal according to claim 1, characterized in that: In step two, the crankshaft is rotated until the connecting rod journal is at top dead center. At this point, the generatrix of the connecting rod journal is measured as b. Therefore, 1 / 2 crankshaft stroke (1 / 2S) is: 1 / 2S = bF / 2 - a + E / 2.

4. The method for measuring the phase angle of a crankshaft connecting rod journal according to claim 1, characterized in that: After measuring the phase angles of the connecting rod journals of the remaining cylinders, the measured phase angles are calculated according to the firing order of the diesel engine.

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