JP2883117B2 - Engine assembly condition inspection method - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an engine assembly state inspection method for inspecting an assembly state of a motion system in an engine during assembly.

[Prior art and its problems] At the time of assembling a vehicle engine, between a connecting rod and a piston pin and between a crankpin of a crankshaft, between a crankshaft and a journal metal,
If dirt such as cutting chips is caught in the sliding parts such as, it may cause problems such as seizure. Therefore, it is necessary to carry out a check and inspection in a state where these are assembled.

Conventionally, this checking and inspection work has relied on a sensory test in which a skilled worker manually rotates the crankshaft and senses the rotational resistance sensibly. Currently, because of its efficiency,
After assembling the moving parts such as the crankshaft, the connecting rod and the piston into the cylinder block, the crankshaft is rotated to measure the rotational torque, and the maximum and minimum values of the measured rotational torque are determined in advance. A method of confirming the presence or absence of an abnormality by comparing with a predetermined maximum reference value and minimum reference value is adopted.

However, the rotational torque of the crankshaft in a state where the piston is assembled is largely fluctuated due to the chatter of the piston ring accompanying rotation, and therefore, the fluctuation of the maximum value and the minimum value is also large. Inspection accuracy was extremely poor, unlike any sensory test performed by an operator.

[Object of the Invention] In view of the above circumstances, an object of the present invention is to provide an engine assembly state inspection method capable of performing a highly reliable inspection based on a measured torque value.

Therefore, in the engine assembly state inspection method according to the present invention, the crankshaft of the engine is rotated while measuring the rotation torque thereof at a predetermined frequency, and the rotation of the crankshaft at which the measured torque value is minimized. The predetermined angle range including the angle is divided into a predetermined minute rotation angle range, an average value of the measured torque in each minute rotation angle range is obtained, and the minimum value in the average value is compared with a minimum torque reference value. , An average value of a minute rotation angle range in a predetermined angle range is integrated, and the integrated value is compared with an integration reference value.

According to this, by averaging the measured torques in the minute rotation angle range, it is possible to obtain a substantially stable torque value excluding the influence of noise caused by chattering of the piston ring, etc. By integrating the average value of the minute rotation angle range within the angle range and comparing it with the integrated reference value, it is possible to make a determination in consideration of the torque value change rate. That is, the determination can be made from both the absolute value of the peak of the torque value and the rate of change of the torque value, and a highly reliable and stable inspection can be performed.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 shows an inspection apparatus 10 for inspecting an assembled state of an engine using an engine assembled state inspection method according to the present invention.

The illustrated inspection apparatus 10 includes a DC motor 13 as a driving source, a torque transducer 11 as a torque detecting unit, and a rotary encoder 12 with a Z phase, and includes a crankshaft 1A of the engine 1 and the DC motor 13. Are connected to the gear train via a torque transducer 11 so that the rotational torque of the crankshaft by the DC motor 13 can be measured in correspondence with the rotational angle measured by the rotary encoder 12.

The torque value measured by the torque transducer 11 and the rotation angle measured by the rotary encoder 12 are input to a control device 20 having a CPU, and are processed by a calculation unit 21 in the control device 20, and a reference value is determined by a determination unit 22. It is configured to make a determination by comparing with.

Hereinafter, a method of inspecting the in-line four-cylinder engine 1 using the inspection device 10 will be described as an example.

When the crankshaft of the in-line four-cylinder engine 1 was driven to rotate at a constant speed and its torque was measured, the torque value for the rotation angle was obtained by taking the rotation angle of the crankshaft on the horizontal axis and the torque value on the vertical axis. As shown in FIG. 2 (A) which is a graph, a curve showing a low value every 180 ° is drawn. 0 ° is the piston 1 of the 1st and 4th cylinders
P and 4P are at top dead center, pistons of cylinders 2 and 3
2P and 3P are at the bottom dead center.

This is because the rotational movement of the crankshaft when it is rotationally driven is most efficiently converted to linear motion (reciprocating motion of the piston), that is, at the angle at which the connecting rod is tangential to the orbital circle of the crankpin. The rotational torque of the crankshaft is the maximum, and the efficiency of converting the rotary motion into linear motion is the lowest when the piston is at the top dead center or the bottom dead center (the piston is not driven at the dead center), so the torque is the lowest. by. FIG. 3 shows a graph of the relationship between the rotation angle of the crankshaft and the moving speed of the piston at the time of constant speed rotation of the crankshaft. It is experimentally confirmed that the magnitude of the moving speed of the piston coincides with the increase and decrease of the torque value. Has been verified.

For in-line 4-cylinder, piston 1 of cylinders 1 and 4
P, 4P and pistons 2P, 3P of the 2nd and 3rd cylinders are
Each has exactly the same positional relationship, and both are arranged with a phase difference of 180 ° depending on the rotation angle of the crankshaft.

Here, the measured torque value differs depending on the moving direction of the piston due to the difference in the sliding resistance caused by the shape of the piston ring (the sliding resistance is smaller in the compression and exhaust processes). 2B, the torque value is shown in FIG. 2 (B) when only pistons 1P and 4P of cylinders 1 and 4 are used, and in FIG. The case of only 3P is shown respectively, and FIG. 2 (A) described above shows a combination of both. In addition, as a result, substantially the same torque curve is obtained in a 180 ° cycle, but the curve is not exactly the same due to a difference in the positional relationship between the crankshaft and the piston.

By the way, if dust such as cutting chips is caught in the sliding portion between the connecting rod and the piston pin and between the crankpin of the crankshaft, and between the crankshaft and the journal metal, naturally, As a result, the torque value increases.

Therefore, although the presence or absence of abnormality can be confirmed by comparing the minimum value of the torque with the reference value, the measured torque value has a large fluctuation as shown in the actual measurement data in FIG. 4, and the peak value is simply compared. Therefore, high inspection accuracy cannot be expected and its reliability is low. The graph showing the change in torque shown in FIG. 4 shows an in-line 4-cylinder engine in which a crankshaft, a connecting rod, and a piston are assembled to a cylinder block. The crankshaft is rotated at 20 rpm, and the rotational torque is reduced every 1 ms. It was obtained by measurement.

Therefore, the predetermined angle range to be measured is set to a range of 5 ° centered on the rotation angle (180 ° interval) at which the torque value known in advance shows the minimum value as shown in FIG. The angle is measured with two or more rotation angles at which the positional relationship between the pistons is exactly the same.

That is, in the case of the in-line four cylinders of the present embodiment, for example, at least four positions of 180 °, 360 °, 540 ° and 720 ° (shown by A, B, C, and D in FIG. 5: 180 ° and 540 ° Is when pistons 1P and 4P are at top dead center, and 360 ° and 720 ° are when pistons 2P and 3P are at top dead center).

The measurement range (5 °) at each rotation angle is further divided into 1 ° increments as a predetermined minute rotation angle range.
Calculate the average value of the rotational torque in

As a result, for each measurement angle, five average torque values for each 1 ° (A _{1 to} A ₅ , B _{1 to} B ₅ , C _{1 to} C ₅ , respectively in FIG. 4)
D ₁ to D shown in ₅₎ is obtained.

Next, two-stage determination is performed using the average torque value for each 1 ° as shown in the flowchart of FIGS. 6 (A) and 6 (B).

[Determination I] First, the minimum (A _MIN , B _MIN , C _MIN , D _MIN ) of the five average torque values at each measurement angle is compared with those at other angles under the same condition (A _MIN and A _MIN ). C _MIN , B _MIN and D _MIN ), and compares the larger value with a predetermined MIN upper limit judgment reference value: X _MAX. (Yes). Also, the smaller value of the comparison result is compared with a predetermined MIN lower limit determination reference value: _XMIN, and when this value exceeds the determination reference value (small), it is determined that there is an abnormality.

That is, pistons 1P and 4P of cylinders 1 and 4 are at top dead center
Compare the minimum average values of 180 ° and 540 °, and compare the minimum average values of 360 ° and 720 ° with pistons 2P and 3P of cylinders 2 and 3 at the top dead center, respectively. Are determined, and the pass / fail judgment is made by comparing the respective values with the judgment reference values.

That is, here, 1 as the predetermined minute rotation angle range
The minimum value of the average torque value within the range of ° is regarded as the substantial minimum torque peak value from which noise components have been removed, and by comparing this with the reference value, stable determination can be performed with high accuracy. You can do it. Also, by comparing the piston position with the measured value at another measurement position under the same condition and comparing it with the reference value, even if there is an abnormal periodicity or if there is an erroneous detection due to the inspection device, It can respond, and inspection reliability is improved.

The reason for determining that there is an abnormality even when the minimum torque value is smaller than the MIN lower limit decrease determination reference value is that it is possible to forget to assemble parts (such as a journal metal or a piston ring).

[Determination II] Next, the rotation angle including the torque value compared with the MIN lower limit reduction determination reference value in the above-described determination I (that is, the smallest one of the average torque values at the measured rotation angle is determined under the same condition) Of all the average torque values of the measured rotation angles of the above (the rotation angle is larger than the smallest one) and add this value (for example, A ₁ + A ₂ + A ₃ + A ₄ + A ₅ = A _TOTAL ) Comparison with a predetermined integration reference value: X _TOTAL , and the integration reference value: X _TOTAL
If it is larger, a failure determination is made.

That is, according to this, the integrated value of the average torque value from which the noise component has been removed within the predetermined angle range is compared with the reference value to determine substantially the change in the torque value within the range. Thus, the ratios can be compared with each other, and unlike the case where only the absolute value of the peak value is compared, a highly reliable judgment can be made.

In the above-described embodiment, the torque value at the angular position of the crankshaft at which the torque value shows the minimum value is compared with the reference value. The torque value at the position may be similarly compared to a maximum reference value, which may result in a more reliable test. In the embodiment, the predetermined angle range to be measured is 5 ° and the predetermined minute rotation angle range is 1 °, but the present invention is not limited to this.

Furthermore, although the embodiment has been described with reference to an example of an in-line four-cylinder engine, it is needless to say that the present invention can be applied to other types of engines such as an in-line six-cylinder engine.

[Effect of the Invention] As described above, according to the engine assembly state inspection method of the present invention, the absolute value of the peak is compared using the average value from which noise has been removed, and the average value is integrated within a predetermined range. By comparing the torque value with the reference value, the rate of change of the torque value is approximately compared, and an extremely accurate and highly reliable inspection can be performed.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of an inspection device used in an engine assembly state inspection method according to the present invention. FIG. 2 (A) is a graph showing torque value variation with respect to a rotation angle of a crankshaft of an in-line four-cylinder engine. ) Is a graph showing the torque value variation with respect to the rotation angle of the crankshaft using only the first and fourth cylinders, (C) is a graph showing the torque value variation with respect to the rotation angle of the crankshaft using only the first and fourth cylinders, FIG. 3 is a graph showing the relationship between the rotation angle of the crankshaft and the moving speed of the piston at the time of constant speed rotation of the crankshaft, FIG. 4 is a graph showing measured torque values, and FIG. FIG. 6A is a diagram showing an angle range and a predetermined minute rotation angle range, and FIG.
(B) is a flowchart according to the judgment II. 1 ... Engine, 1A ... Crankshaft, 10 ... Inspection device,
11: Torque transducer, 12: Rotary encoder, 13: DC motor, 20: Control device, 21: Operation unit, 22: Judgment unit

Claims (2)

(57) [Claims] An engine crankshaft is rotated while measuring its rotation torque at a predetermined frequency, and a predetermined angle range including a rotation angle of the crankshaft at which a measured torque value is minimum is divided into a predetermined minute rotation angle range. The average value of the measured torque in each of the minute rotation angle ranges is obtained, the minimum value of the average values is compared with the minimum torque reference value, and the average of the minute rotation angle range in the predetermined angle range is obtained. Integrating the values and comparing the integrated value with an integrated reference value. 2. The method according to claim 1, wherein the predetermined angle range includes an angle of the crankshaft when the piston is at a top dead center or a bottom dead center.