JP2000028324A - Device for diagnosing degree of extension of chain - Google Patents

Abstract

PROBLEM TO BE SOLVED: To accurately diagnose the abnormal extension of a chain. SOLUTION: This diagnostic device is provided with chain passage detecting parts 12A-12C for detecting the passage of the inner link parts and external link parts of the chains 20A-20C, measuring part 17 for measuring the pulse period of the inner link part and the pulse period of the external link part from the pulse signals of the chain passage detectors 12A-12C, judging part 18 for judging the degree of extension of the chins 20A-20C from the change of the pulse period of the inner link part and the pulse period of the external link part, predicting part 19 for predicting an abnormal state period or a chain exchange appropriate period by comparing the diagnostic result with the previous diagnostic result, and storage part 25 for storing the result of the judging part 18.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a chain length diagnosing device for diagnosing chain length.

[0002]

2. Description of the Related Art Passenger conveyors, which are generally known as conveyors, are provided with steps for carrying passengers and goods, and handrails so that passengers can ride with peace of mind. It is configured to move endlessly in synchronization with the chain. This chain elongates over time, and the degree of elongation varies depending on the use time and load conditions, so periodic maintenance and inspection work is required. As described in Japanese Patent Application Laid-Open No. 7-137976, a conventional elongation detecting device for a chain that detects this elongation is provided with a sign on the chain, and a detecting device that detects the passage of the sign per unit of the chain. One that detects the length has been proposed.

[0003]

However, in the conventional chain elongation detecting device, since a mark is provided on the chain for detecting the elongation of the chain as described above, the elongation of the existing chain is detected. In order to do so, a new sign had to be provided, which required a great deal of labor and time. Also, even in the case of a new chain, it is difficult to ensure the reliability in determining the degree of elongation because the accuracy of sign installation greatly affects the detection result. Must be provided on the side of the chain, and the sensor for detecting the sign must be arranged close to the side of the chain in accordance with this. Due to the vibration, it is very difficult to always detect the sign with a sensor fixed at a predetermined position.

When the chain meshes with a sprocket driven in rotation, the pitch circle diameter of the sprocket matches the center of the roller of the chain in the initial state of the chain. However, when the chain is extended, the center of the roller of the chain is larger than the pitch circle diameter of the sprocket. It will be rotationally driven out of position. Therefore, even if the angular speed of the sprocket driven by rotation does not change over time, the circumferential speed of the chain meshing with it changes over time, and the operating speed of the extended chain is faster than the initial state, so the chain Even if the length increases, it is almost the same as the passing time of one round of the chain in the initial state. For this reason, even if a sign is provided on the chain at regular intervals and the passage of the sign is detected,
It was difficult to detect the length of the chain per unit, and it was difficult to accurately detect the elongation of the chain.

It is an object of the present invention to provide a chain elongation degree diagnostic apparatus capable of accurately diagnosing abnormal elongation of a chain.

[0006]

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention provides a chain elongation diagnostic device for diagnosing the elongation of a chain in a conveyor combined with a chain. A chain passage detector for detecting passage of an outer link portion, a pulse measuring section for measuring a pulse period of the inner link portion and the outer link portion of the chain from a pulse signal of the chain passage detector, and a A determination unit is provided for determining abnormal elongation of the chain based on a change in the pulse period of the inner link portion and the outer link portion.

As described above, the chain elongation degree diagnostic apparatus of the present invention is provided with a chain passage detector near the chain to detect the pulse period of the chain from the steel portion of the roller. Since the abnormal elongation is diagnosed, the abnormal elongation can be diagnosed accurately without providing a mark on the chain at regular intervals as in the related art.

[0008]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 7 is a side view showing a main drive mechanism of an escalator to which the chain elongation degree diagnostic device according to one embodiment of the present invention is attached. The escalator driving driving machine 2 provided in the machine room is connected to an upper driving step chain sprocket 4 via a driving chain 3. A handrail driving sprocket 6 supported by the same shaft 5 as the upper driving step chain sprocket 4 is connected to a double sprocket 8 via a handrail driving main chain 7. A driving roller 11 of a handrail driving device 10 is connected to the double sprocket 8 via a driving chain 9 for driving a handrail, and the endless handrail 1 is formed via the driving roller 11.
Is rotated. Further, a chain guide 13 including a chain passage detector 12 is arranged corresponding to the handrail driving main chain 7 located between the double sprocket 8 and the tension sprocket 14. The chain guide 13 is not limited to the portion corresponding to the main chain 7 for driving the handrail, and may be attached to the dry chain 9 for driving the handrail or the driving chain 3. It may be installed anywhere between the sprockets. In addition, the chain passage detector 12 is not affected by oil, dust, or water peculiar to the chain driving portion,
A magnetic sensor or the like that outputs a signal only depending on the roller portion of the chain, which is a steel portion, that is, only by the presence or absence of metal shielding is used.

FIG. 1 shows the above-described chain passage detector 12.
FIG. 1 is a block diagram showing a chain elongation degree diagnosing device configured by using FIG. A plurality of chains 20A, 20B, 2
Chain passing detectors 12A and 12
B, 12C are attached, and these chain passage detectors 12A to 12C are connected to the MPU 2 via the switching unit 16.
4 is connected. When the chain passage detector 12A finishes detecting the pulse of the chain 20A, the switching unit 16 switches the chain passage detector 12B to a detectable state and further switches the chain passage detector 12C to a detectable state. Can be. The MPU 24 includes a measuring unit 17 that measures a pulse width between rollers of the chains 20A to 20C from a pulse signal detected by the chain passage detectors 12A to 12C, and a chain 20A to 2 that is measured by the measuring unit 17.
Compare the pulse period of the chain based on the pulse width between rollers of 0C to diagnose abnormal elongation,
From the determination unit 18 for quantitatively determining the degree of elongation of the chain 20A to 20C and the determination result of the degree of elongation of the chains 20A to 20C by the determination unit 18, for example, the latest determination result is compared to calculate the amount of change. Is divided by an elapsed time to obtain a change amount per unit time, and a prediction unit 19 for predicting a chain abnormality time or a chain replacement time indicating a time until the elongation of the chains 20A to 20C reaches an abnormal state. I have.

A monitoring center 27 is connected to the MPU 24 via a storage unit 25 and a communication unit 26. The storage unit 25 stores the measurement results of the measurement unit 17 and the judgment unit 1
8, the chain abnormal time and the chain replacement time in the prediction unit 19, and information such as the date and time when the diagnosis is performed, and the communication unit 26 stores the information stored in the storage unit 25. It is transmitted to the monitoring center 27 periodically,
In an emergency situation in which the prediction unit 19 predicts that the chains 20A to 20C have reached the abnormal time, a chain exchange instruction or the like is transmitted to the monitoring center 27. Further, for example, when it is determined from the determination result of the elongation degree of the chains 20A to 20C by the determination unit 18 that the chain has reached the abnormal state,
The determination unit 18 is configured to control the chain drive by giving a command to the drive control unit 28.

Here, the process of elongation of the chain will be described. Chain elongation is categorized into elastic elongation, plastic elongation and abrasion elongation, and generally referred to as elongation of the chain is abrasion elongation, which accounts for the largest proportion of elongation. , About this abrasion elongation,
FIG. 2 is a cross-sectional view when the chain is viewed from the center to the outside.
FIG. 3 is a cross-sectional view showing an initial state along the line BB of FIG. 2, and FIG. 4 is a cross-sectional view showing a state of abrasion and elongation along the line BB of FIG. explain.

The chain 20 includes an inner link plate 21B and an outer link plate 21A which are alternately arranged.
And a roller 15 which is arranged at the connecting portion of the two link plates 21A and 21B and is engaged with the sprocket, and is detected by the above-mentioned chain passage detectors 12A to 12C. A bush 22 fitted into the plate 21B, and an outer link plate 21 inserted into the bush 22 and
A is composed of a pin 23 fitted in A. Here, a gap exists between the roller 15 and the bush 22 and between the bush 22 and the pin 23, and the roller 15 freely rotates between the bush 22 and the bush 22. Since the pin 23 is fixed to the outer link plate 21A, the pin 2 is fixed.
3 and the bush 22 themselves do not rotate. The fact that the chain bends or meshes with the sprocket and the trajectory draws an arc is a phenomenon in which the bush 22 and the pin 23 swing due to the gap existing between the bush 22 and the pin 23.

Since the chain 20 has such a configuration, when the chain 20 is rotated and bent by meshing with the sprocket, the pin 23 and the bush 22
The wear between the outer surface of the pin 23 and the inner surface of the bush 22 progresses due to the rocking during the rotation, and abrasion elongation occurs in the direction in which the gap increases. When the chain 20 is worn and stretched, the chain 20 is always pulled in both directions during driving of the chain 20 as shown by arrows in FIG. The distance from the surface to the outer diameter surface of the roller 15 adjacent thereto changes. On the other hand, the inner link plate 21 on which the bush 22 is fixed
The roller-to-roller dimensions j2 and j4 in B do not change, and j2 = j2 'and j4 = j4' even in the abrasion-elongated state. Further, the outer link plate 2 on which the pin 23 is fixed is provided.
When the distances j1 and j3 between the rollers in 1A are abraded and expanded, they expand from j1 to j1 'and from j3 to j3', respectively, and the entire chain 20 expands. Roller 1
The diameter of the roller 5 is reduced by the abrasion of the outer surface of the roller 15 in contact with the sprocket, but the amount of abrasion is not as large as the gap between the pin 23 and the bush 22,
Here, the amount of change can be ignored.

Next, the principle of operation of the chain elongation diagnostic apparatus utilizing the above-described characteristics of abrasion elongation will be described with reference to FIG. 5 which is a waveform diagram of an output signal of the chain in an initial state shown in FIG.
This will be described with reference to FIG. 6, which is a waveform diagram of the output signal of the chain in the abraded state shown in FIG. In FIG. 5, the pulse widths H1, H2, H3, H4 from the rise to the fall of the pulse forming the peak of the waveform are the outer diameter portions h1, h2, h3, h4 of the roller 15 shown in FIG. And the pulse intervals J1, J2 from the fall to the rise of the pulse forming the valley.
J3, J4 are dimensions j1, j2, j3, j from the outer surface of the roller 15 shown in FIG.
4 corresponds to the transit time. The diameter of the roller 15 is h1
= H2 = h3 = h4, the corresponding pulse width of the transit time is also H1 = H2 = H3 = H4. Since the chain in the initial state has no abrasion elongation, the dimension from the outer surface of the roller to the outer surface of the adjacent roller is j1 = j2 = j3 = j4.
And the corresponding pulse interval is also J1 = J2 = J3
= J4.

When the chain is worn from the initial state shown in FIG. 3 to the worn-out state shown in FIG. 4, the overall length of the chain becomes longer. The chain that matches the roller center of the meshing chain but is worn and stretched is rotated with the roller center of the meshing chain shifted to a position larger than the pitch circle diameter of the sprocket. For this reason, even if the angular speed of the sprocket driven by rotation does not change over time, the peripheral speed of the chain that meshes with the sprocket is different between the initial state and the extended state of the chain,
The running speed of the chain in the abraded state is faster than that in the initial state. As a result, even if the chain extends, the transit time of one round of the chain in the initial state and in the extended state hardly changes, so that the pulse widths H1 'to H4' are smaller than the pulse widths H1 to H4.

Here, assuming that the abrasion amount of the roller diameter is very small because the abrasion amount of the roller diameter is very small, if the chain is worn and stretched, the distance from the center of the adjacent roller 15 supported by the outer link plate 21A in FIG. The dimensions up to the roller center are dimensions K1 and K2 in FIG. 3, and dimensions K1 'and K2' in FIG.
The dimensions from the roller center to the roller center of the adjacent rollers 15 supported by the inner link plate 21B are dimensions L1 and L2 in FIG. 3, and dimensions L1 ′ and L2 in FIG.
L2 '. The dimensions K1 and K1 'in FIGS. 3 and 4 are the transit times F1 and F1' in the output signals of FIGS.
The dimensions K2 and K2 'are the transit times F2 and F2', the dimensions L1 and L1 'are the transit times G1 and G1' and the dimension L
2, L2 'becomes the passing time G2, G2'.

When the chain is worn from the initial state, the operating speed of the chain increases, so that the distance between the outer surfaces of the adjacent rollers 15 supported by the inner link plate 21B does not change. , Transit time J2
Is transit time J2 ', transit time J4 is transit time J
4 ', while the outer link plate 21A
Since the distance from the outer surface of the adjacent roller 15 supported by the outer surface to the outer surface increases, the transit time J1 becomes the transit time J1 ′.
In addition, the passage time J3 increases to the passage time J3 '. Comparing the initial state of the output signals of the chain passage detectors 12A to 12C and the time passage of the abraded state as described above, the adjacent state supported by the outer link plate 21A for one round of the chain in the initial state. The sum F of the pulse periods of the distance between the centers of the rollers 15 and the inner link plate 21B
The total sum G of the pulse periods of the distance between the centers of the adjacent rollers 15 supported by the following formulas (1) and (2) is expressed by the following equation (1) and equation (2), and the difference M = FG is substantially equal to zero. F1 + F2 + F3... = F (1) G1 + G2 + G3... = G (2) On the other hand, the adjacent rollers 15 supported by the outer link plate 21A for one circumference of the chain in a worn and stretched state.
, And the sum G ′ of the pulse periods of the center-to-center dimensions of the adjacent rollers 15 supported by the inner link plate 21B is expressed by the following equations (3) and (4). And the difference M ′ = F′−G ′. F1 ′ + F2 ′ + F3... = F ′ (3) G1 ′ + G2 ′ + G3... = G ′ (4) Here, the difference M in the initial state is M ′ in the state of abrasion and elongation, and the abrasion elongation is small. Since M ′ increases as the size increases, the difference M in the pulse period in the initial state and the difference M ′ in the pulse period in the abraded state are compared and calculated, and the difference between M ′ and M becomes a preset value. It is possible to determine the abnormal elongation of the chain based on whether or not it has reached. Further, the pulse widths H1 to H4 in the initial state change from H1 ′ to H4 ′ due to the increased chain operation speed in the worn state, so that the difference H1 ″ = H1−H1 ′ is calculated. Alternatively, the sum H of the pulse width in the initial state and the sum H ′ of the pulse width in the abraded state are obtained by Expressions (5) and (6),
By comparing the difference H ″ = H−H ′, it is possible to quantitatively determine the degree of elongation of the entire chain based on whether or not H ″ has reached a preset value. H = H1 + H2 + H3 + H4 +... + Hn (5) H ′ = H′1 + H′2 + H′3 + H′4 +. Then, by storing the result of the elongation degree and dividing the result by the elapsed time of the chain drive to calculate, the elongation degree of the chain at present, the amount of elongation per unit time, and the elongation degree of the chain after several hours of driving the chain are obtained. Since it is possible to quantitatively determine and predict, it is also possible to predict the abnormal state time.

FIG. 8 is a flowchart showing a diagnosis procedure of the above-described chain elongation degree diagnostic apparatus. First, in steps S1, chains 20A to 20A are used to measure and determine the degree of elongation.
0C, and the switching unit 16 first selects the chain passage detectors 12A to 12C.
Select A. The detection of the pulse for each link of the chain selected in step S2 is started, and the passage time of each link of the chain is measured. Thereafter, in step S3, it is determined whether the measured pulse period of one link is an even number. Since the first detected pulse is the first, the step S3 is performed.
If the elongation occurrence state is diagnosed in step 4, the passing time F1 'in FIG.
Are recorded as odd-numbered passage times. Next, the pulse period detected secondly is recorded as the passage time G1 ′ even-numbered passage time shown in FIG. 6 if the elongation occurrence state is diagnosed.

In this way, the transit time, which is the pulse period for each link, is recorded for each link separately for odd-numbered and even-numbered ones. In step S6, it is determined whether the number of links for one round of the chain being measured has been reached. When the detection of the passing time of one round of the chain and the recording of the result of the measurement are completed, step S
7, the sum of the odd-numbered pulse periods for one round of the chain,
The sum of the even-numbered pulse periods is calculated. The sum F ′ of the odd-numbered pulse periods is represented by Expression (3), and the sum G ′ of the even-numbered pulse periods is represented by Expression (4).

Next, in step S8, the sum F 'of the odd-numbered pulse periods is compared with the sum G' of the even-numbered pulse periods. As a result, when the sum F 'around the odd-numbered pulse is larger, it is determined in step S9 that the odd-numbered pulse period is the pulse period of the outer link portion and the even-numbered pulse period is the pulse period of the inner link portion. On the other hand, if the sum G 'of the even-numbered pulse periods exceeds the sum F' of the odd-numbered pulse periods in the determination in step S8, the even-numbered pulse period is the pulse period of the outer link portion in step S10, and the odd-numbered It is determined that the pulse period is for the inner link portion. Next, in step S11, an outer link portion and an inner link portion are distinguished from each other as shown in FIG.
As shown in FIG. 11, a distribution diagram of the pulse period for each link is created.

FIG. 9 is a distribution diagram of the pulse period for each link in the chain in the initial state, and FIG. 10 and FIG.
Is a distribution diagram of the pulse period for each link in a worn and stretched chain. The horizontal axis of each distribution diagram represents the transit time for each link in units of msec, and the vertical axis represents the number of links in the chain. I have. In the chain in the initial state, as shown in FIG. 9, a large amount of data is collected at the peak of the pulse period of 50 msec for each link, and all data is included in the pulse periods within the range of the A line and the B line. However, this shows that the distributions of the inner link portion and the outer link portion have almost the same tendency since the distance intervals do not substantially change.

On the other hand, when the chain becomes worn and stretched, the running time is shortened because the operating speed of the chain increases and the distance between the inner links does not change due to the meshing characteristics of the chain and the sprocket and the structure of the chain. ,
Further, since the distance interval between the outer link portions is increased, the transit time becomes longer. Therefore, the distribution of the pulse period of only the link of the inner link portion of the abraded chain has a smaller distribution time as shown in FIG. 10 than the distribution of the initial state shown in FIG. In addition, a link having a pulse cycle shorter than the line A has occurred. Here, even if there is a characteristic of the chain that the distance interval of the inner link portion does not change even when abrasion elongates, even if there is a link having a pulse cycle shorter than the A line, a local abnormal elongation occurs. If the link portion affects the engagement with the sprocket, it is considered that the chain has caused local abnormal elongation at the same time since the inner link portion having a very short transit time is detected.

The distribution of the pulse period of only the link of the outer link portion of the abraded chain is different from the distribution of the chain in the initial state shown in FIG. 9, as shown in FIG. Are increased and distributed, and a link having a pulse cycle exceeding the B line occurs. As a characteristic of the chain, the distance interval of the outer link part expands due to abrasion and elongation, so a link with a pulse period exceeding the B line occurs because the outer link part has caused local abnormal elongation it is conceivable that.

After the distribution chart has been prepared in this way, in step S11, the presence / absence and number of pulse periods shorter than the line A and the presence / absence and number of pulse periods beyond the line B are calculated to calculate a chain deterioration index. . Step S12
Then, the elongation percentage of the entire chain is calculated from the difference between the total transit times of the outer link portion and the inner link portion. Then, in step S13, it is determined whether the chain deterioration index calculated in step S11 or the elongation rate of the entire chain calculated in step S12 has reached a use limit by comparing with a predetermined set value. If it is determined in step S13 that the usage limit has not been reached, the prediction unit 19 predicts an abnormal state of the chain or an appropriate chain replacement time in step S15, and then determines the measurement result and the degree of chain elongation in step S16. Information such as a result, a chain abnormal state prediction time, a chain replacement proper prediction time, and a date and time when the diagnosis is performed is stored in the storage unit 25. The information stored in the storage unit 25 is
It is transmitted from the communication unit 26 to the monitoring center 27 periodically. However, if it is determined in step S13 that the usage limit has been reached, in step S14, chain drive control such as stopping or reducing the speed by giving a command to the drive control unit 28 shown in FIG. 1 is performed. Or a chain exchange command is transmitted from the communication unit 26 to the monitoring center 27.

As described above, according to the chain elongation diagnostic apparatus of the present embodiment, the chain passage detectors 12A to 12C are provided near the chain to detect the steel portion of the roller 15 and to measure the pulse period of the chain. Since the abnormal elongation of the chain is diagnosed from the above, accurate abnormal elongation can be diagnosed without providing a plurality of signs of the chain as in the related art. Moreover, it is also possible to carry out inspection and adjustment work at an appropriate time by predicting the chain elongation by performing periodic measurement from the start time of the chain without the intervention of maintenance personnel. Further, since the chain elongation can be predicted, it is possible to prevent the occurrence of an abnormality beforehand, and it is possible to improve the reliability of the transfer device. Further, the operation stop time for maintenance and inspection can be reduced in a passenger conveyor such as an escalator, so that the usage of customers can be increased.

In the above-described embodiment, the chain elongation is calculated from the pulse period for one round of the chain. However, the chain elongation may be calculated from the pulse period for each predetermined section. Although the escalator is illustrated as a transport device, the present invention can be similarly applied to a moving walkway, an automatic line, and other transport devices if a drive mechanism using a chain is employed.

[0027]

As described above, the chain elongation diagnostic apparatus according to the present invention is provided with a chain passage detector near the chain to diagnose abnormal elongation of the chain from a change in the pulse period of the chain measured. As a result, it is possible to accurately diagnose abnormal extension without providing a plurality of markers on the chain as in the related art.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a chain elongation degree diagnostic apparatus according to an embodiment of the present invention.

FIG. 2 is a cross-sectional view of a chain to which the elongation degree diagnostic device for a chain shown in FIG. 1 is applied.

3 is a cross-sectional view of the chain shown in FIG. 2 in an initial state along line BB.

FIG. 4 is a cross-sectional view of the chain shown in FIG.

FIG. 5 is a waveform diagram of an output signal when the chain elongation degree diagnosing device shown in FIG. 1 is used for a chain in an initial state.

FIG. 6 is a waveform diagram of an output signal when the chain elongation diagnostic device shown in FIG. 1 is used for an abraded chain.

FIG. 7 is a side view showing a main part of the escalator in a state where the elongation degree diagnosing device of the chain shown in FIG. 1 is attached.

FIG. 8 is a flowchart showing a diagnostic procedure performed by the chain elongation degree diagnostic apparatus shown in FIG. 1;

9 is a distribution diagram of a pulse period of a chain in an initial state by the chain elongation degree diagnostic apparatus shown in FIG. 1;

FIG. 10 is a distribution diagram of pulse periods of a chain that has been worn and stretched by the chain length diagnosing device shown in FIG. 1;

FIG. 11 is a distribution diagram of pulse periods of another chain that has been worn and stretched by the chain length diagnosing device shown in FIG. 1;

[Explanation of symbols]

 12A, 12B, 12C Chain passage detector 17 Measurement unit 18 Judgment unit 19 Prediction unit 20A, 20B, 20C Chain 24 MPU 25 Storage unit 26 Communication unit

Continued on the front page (72) Inventor Yoshio Matsuzaki 1-6-6 Kandanishikicho, Chiyoda-ku, Tokyo Inside the Hitachi Building System Co., Ltd. (72) Inventor Tomoya Takei 1-6-6 Kandanishikicho, Chiyoda-ku, Tokyo Hitachi Building, Ltd. In the system (72) Inventor Kyoya Asaki 1-6-6 Kandanishikicho, Chiyoda-ku, Tokyo Co., Ltd. Hitachi Building Co., Ltd. (72) Inventor Hiroshi Kubota 1-6-6 Kandanishikicho, Chiyoda-ku, Tokyo Hitachi Building Co., Ltd. In-system (72) Inventor Yoshiyuki Kurimata 1-6-6 Kandanishikicho, Chiyoda-ku, Tokyo F-term in Hitachi Building System Co., Ltd. (Reference) 2F065 AA63 AA65 CC00 DD06 FF32 PP22 QQ41 SS09 3F321 AA02 CA25 EA14 EB07 EC06 HA04

Claims (3)

[Claims] 1. A chain elongation degree diagnostic device for diagnosing the elongation degree of a chain in a transport device combined with a chain, comprising: a chain passage detector for detecting passage of an inner link portion and an outer link portion of the chain; A pulse measuring unit that measures a pulse period of the inner link portion and the outer link portion of the chain from a pulse signal of the chain passage detector; and a chain based on a change in the pulse period of the inner link portion and the outer link portion of the chain. And a determining unit for determining abnormal elongation of the chain. 2. The chain according to claim 1, further comprising an abnormal state timing predicting unit for predicting a proper replacement timing of the chain by comparing the result of the previous measurement by the pulse measuring unit with a previous timing. Stretch degree diagnostic device. 3. The diagnostic device according to claim 1, wherein the determining unit determines the elongation degree of the chain from a change in the number of the pulse periods exceeding a predetermined range. apparatus.