JPH11247951A - Prediction device for belt lifetime - Google Patents

Abstract

PROBLEM TO BE SOLVED: To predict a lifetime of a toothed belt with a high degree of accuracy in view a measured temperature thereof with no complicated computation, by installing a belt lifetime predicting device on a power transmission provided in a vehicle engine or the like. SOLUTION: A toothed belt 10 is wound on a driven pulley 21 and a drive pulley 22 so as to transmit the rotation of the drive pulley 22 to the driven pulley 21. A temperature sensor 31 of a belt worn-out predicting device 30 is provided to the rear surface or the toothed surface side of the toothed belt 10 in the vicinity of the drive pulley 22. During driving of the drive pulley 22, the temperature of the material of the toothed belt 10 is measured by the temperature sensor 31 at every fixed drive time. A control device 32 predicts a lifetime of the toothed belt 10 in view of a variation in the gradient of the thus detected temperature with respect to the drive time.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a device for estimating the life of a toothed belt used in a power transmission device for transmitting the rotational force of each shaft between, for example, an output shaft of a vehicle engine and an auxiliary shaft.

[0002]

2. Description of the Related Art Conventionally, a toothed belt is formed, for example, by forming belt teeth on one surface of a belt body and embedding a core wire in the belt body. In recent years, as the performance of the engine has been improved, the load applied to the toothed belt has increased, and when the belt has been used for a long period of time, cracks have occurred in the belt teeth due to cracking. For this reason, Japanese Patent Application Laid-Open No. Hei 7-332443 has devised a method of predicting the time at which the belt teeth are missing, that is, the service life of the belt, and predicting the belt replacement time. In this prediction method, geometric data, material data, external force data, and the like are obtained for a toothed belt, a pulley, and the like, and these data are analyzed to predict the tooth portion reaction force distribution characteristics applied to the belt. Then, the life of the belt is predicted by comparing the predicted tooth part reaction force distribution characteristic with the SN curve in which the durability life characteristic according to the tooth part reaction force distribution is set in advance.

[0003]

In the conventional prediction method described above, it is necessary to measure an SN curve in advance, and a large amount of data is required for a toothed belt, a pulley, and the like. Therefore, the calculation for collating with the SN curve is complicated. Furthermore, since external force data and the like need to be obtained by conducting tests using a predetermined analysis model, it is impossible to predict the service life by mounting it on a power transmission device provided in an actual engine or the like. Is difficult to predict with high accuracy.

According to the present invention, a belt life predicting device is mounted on a power transmission device provided in a vehicle engine or the like, and the temperature of the toothed belt can be measured easily without complicated calculations to achieve high precision. The purpose is to predict the life of the belt.

[0005]

SUMMARY OF THE INVENTION A belt life predicting device according to the present invention is provided near a toothed belt and detects temperature of a base material which is a temperature of a rubber material constituting the toothed belt. A life predicting means for predicting a belt life, which is a time at which the belt teeth of the toothed belt are chipped, based on the base material temperature.

[0006] Preferably, the temperature detecting means is provided to face the toothed surface portion of the toothed belt on which the belt teeth are formed, or the back surface portion where the belt teeth are not formed. Preferably, the toothed belt is wound around a driving pulley and a driven pulley,
While this toothed belt is driven by the drive pulley,
Temperature detecting means detects the substrate temperature.

Preferably, the life prediction means predicts the life of the belt by detecting a temperature gradient of the base material temperature with respect to the driving time of the toothed belt. In this case, the life prediction means
The time when the temperature gradient exceeds the limit value is predicted as the belt life. More preferably, the life predicting means predicts the life of the belt based on a temperature difference between the base material temperature and a reference temperature that is substantially constant with respect to the driving time of the toothed belt.

For example, the temperature detecting means is arranged near the driving pulley.

A belt life predicting method according to the present invention is provided near a toothed belt, detects a base material temperature which is the temperature of a rubber material constituting the toothed belt, and forms a toothed belt based on the base material temperature. The present invention is characterized in that the belt life, which is the time when the belt teeth of the belt are chipped, is predicted.

[0010] Preferably, the toothed belt is wound around a driving pulley and a driven pulley, and the substrate temperature is detected while the toothed belt is driven by the driving pulley. More preferably, the belt life is predicted by detecting a temperature gradient of the substrate temperature with respect to the driving time of the toothed belt. In this case, the life of the belt is predicted as when the temperature gradient has exceeded the limit value.

Preferably, the belt life is predicted based on a temperature difference between the base material temperature and a reference temperature which is substantially constant with respect to the driving time of the toothed belt.

[0012]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a partially cutaway perspective view showing a toothed belt used in a power transmission device.
FIG. 2 is a longitudinal sectional view of the toothed belt broken in a belt longitudinal direction.

The toothed belt 10 includes a tooth surface portion 15 having a plurality of belt teeth 12 formed along the belt longitudinal direction, and a back surface portion 16 having no belt teeth 12 formed thereon.
A core wire 14 is embedded in the back part 16. Belt teeth 1
A tooth cloth 18 is attached to the surface of the second cloth.

The raw material used for the belt teeth 12 and the back portion 16 is, for example, a rubber having improved heat aging resistance, such as hydrogenated nitrile rubber, chlorosulfonated polyethylene, or chloroprene rubber, natural rubber, styrene butadiene rubber, or the like. is there. In this rubber, zinc white, stearic acid, plasticizer, antioxidant, etc. are added as compounding agents,
In addition, sulfur, organic peroxide, and the like are added as a vulcanizing agent.

The core wire 14 is a twisted cord in which filaments such as glass fiber and para-aramid fiber are twisted, and this cord is treated with an RFL liquid as an adhesive.

The tooth cloth 18 is a canvas made of nylon 6, nylon 66 or the like, and the nylon 6 and nylon 66 are used alone or in a mixed state. This canvas is composed of a weft having elasticity in the belt longitudinal direction and a warp having non-elasticity in the belt width direction.

Referring to FIG. 3, the structure of the belt life predicting apparatus of the present invention will be described. FIG. 3 is a schematic diagram illustrating a power transmission device equipped with the belt life prediction device according to the embodiment.

The power transmission device 20 is provided, for example, in a vehicle engine, and includes a driven pulley 21, a drive 22, a toothed belt 10, and a tensioner 23. The driven pulley 21 is connected to a camshaft (not shown), and the drive pulley 22 is connected to a crankshaft (not shown). Pulley teeth (not shown) are provided on the outer peripheral side of the driven pulley 21 and the driving pulley 22.
1, 22 have different numbers of teeth.

The belt 10 shown in FIGS. 1 and 2 is wound around the driven pulley 21 and the driving pulley 22 on the outer peripheral side. The belt teeth 12 of the belt 10 (see FIG. 1) are
Mesh with the pulley teeth. The drive pulley 22 rotates with the rotation of the crankshaft to drive the toothed belt 10. The rotation of the driving pulley 22 is transmitted to the driven pulley 21 by the toothed belt 10. A tensioner 23 for adjusting the tension of the toothed belt 10 is provided between the driven pulley 21 and the driving pulley 22.

When the toothed belt 10 provided in the power transmission device 20 is used for a long time, cracks occur in the base portions 13 (see FIG. 1) of the belt teeth 12 and the belt teeth 12
Leads to tooth loss. Therefore, in order to predict the lack of teeth, the belt life predicting device 30 of the present embodiment uses the power transmission device 20.
It is provided in the vehicle provided with.

The belt life predicting device 30 includes the belt teeth 12
Is a device for predicting the timing of occurrence of missing teeth in the belt, that is, the life of the belt. The temperature of the raw rubber constituting the toothed belt 10 (hereinafter referred to as the base material temperature) is measured, and the belt life is determined based on the base material temperature. Predict.

The belt life predicting device 30 includes a temperature sensor 3
1, a control device 32 and a display device 33.
The temperature sensor 31 is, for example, a non-contact type infrared radiation thermometer, and detects a base material temperature of the toothed belt 10.
Is disposed in the vicinity of the back surface 16 side of the toothed belt 10 or the surface of the toothed belt 15 side. As the temperature sensor, a thermocouple thermometer may be used instead of the infrared radiation thermometer. In this case, a toothed belt 10 is measured by a thermocouple type thermometer.
Is detected instead of the substrate temperature.

A controller 32 is connected to the temperature sensor 31. The control device 32 predicts the life of the toothed belt 10 based on the base material temperature of the toothed belt 10 detected by the temperature sensor 31. A display device 33 for warning the life of the toothed belt 10 is connected to the control device 32. The display device 33 includes, for example, a warning lamp, and turns on the lamp based on a command from the control device 32.

The relationship between the life of the belt and the temperature of the base material of the belt will be described with reference to FIG. FIG. 4 is a diagram showing characteristics of the belt base material temperature with respect to the driving time of the power transmission device, and is a result of a test performed using the power transmission device 20 shown in FIG. In this test, a non-contact infrared radiation thermometer was installed near the back side of the toothed belt 10, and the base material temperature T of the toothed belt 10 was measured by the thermometer. The drive transmission device 20 was driven by a motor connected to a drive pulley 22.

The solid lines A, B, C and the broken line D show the temperature changes of the four types of toothed belts 10 made of different materials. Solid line R
Represents a temperature change around the power transmission device 20 measured as comparison data. Hereinafter, the toothed belts corresponding to the solid lines A, B, and C and the broken line D are referred to as toothed belts A, B, C, and D, respectively. The solid line R is measured as comparison data of the solid line B, and the solid lines A and C and the broken line D
The temperature change measured as the comparison data of is the same as the solid line R, and is omitted in FIG.

The temperature (solid line R) is substantially constant even after the drive time S of the power transmission device 20 has elapsed. On the other hand, the base material temperature T of each belt changes rapidly in a certain time.
For example, in the case of the toothed belt A, the change in the base material temperature T with respect to the driving time of the belt, that is, the temperature gradient changes from the gradient j (dashed-dotted line) to the steep gradient k (dashed-dotted line) in the driving time Sa. Similarly, in each of the belts B, C, and D, the temperature gradient of the base material temperature T sharply changes at each of the driving times Sb, Sc, and Sd. These drive times Sa, Sb, Sc, S
d, each belt A, B, C, D
It was found from tests that cracks occurred at the base 13 of the steel sheet, which was a precursor to tooth chipping. That is, each driving time S
a, Sb, Sc, Sd are the toothed belts A, B, C, D
Is near the end of its life.

As is clear from the above test results, the life of the toothed belt is predicted by detecting when the temperature gradient of the base material temperature T of the toothed belt becomes steep. However, at the time of driving the engine, the base temperature T of the toothed belt is changed due to changes in the driving speed and torque of the engine.
Changes, the temperature gradient of the base material temperature T becomes steep, and the life of the toothed belt may be erroneously predicted. It is necessary to prevent the erroneous prediction of the life of the toothed belt. Therefore, the inventor of the present invention changes the temperature of the cooling water or the engine oil (hereinafter referred to as the reference temperature) in the same manner as the air temperature (solid line R) and the base material temperature T of the toothed belt due to changes in the engine rotation speed and the like. Attention was paid to the fact that when the base material temperature T of the attached belt nears the end of its life, a difference between the reference temperature and a predetermined value (for example, 15 ° C.) or more occurs. That is, by detecting both the temperature gradient of the base material temperature T and the temperature difference between the base material temperature T and the reference temperature, the life of the toothed belt is predicted with high accuracy.

Although FIG. 4 shows the substrate temperature T at relatively long time intervals, in the test, the substrate temperature T was continuously detected at relatively short time intervals. When the belt life prediction device 30 is mounted on an actual power transmission device, the detection of the base material temperature T is performed at a relatively short fixed interval (for example, 5 minutes).
Do with.

Referring to FIG. 5, the procedure of the life prediction performed by the controller 32 of the belt life prediction apparatus 30 will be described. FIG. 5 is a flowchart showing a procedure of the life prediction. The control device 32 is, for example, a one-chip microcomputer dedicated to life prediction processing, and when a vehicle equipped with the belt life prediction apparatus 30 is started,
This process starts.

In step 110, an initial value Tpr of the substrate temperature is set. This initial value Tpr is set to the substrate temperature measured first.

In step 120, the unit time ΔS is measured. The unit time ΔS is, for example, 5 minutes, and the substrate temperature of the toothed belt 10 is detected every unit time ΔS. When the unit time ΔS has elapsed, the process of step 130 is performed.

In step 130, the toothed belt 10
Is measured by the temperature sensor 31 (see FIG. 3). In step 140, the temperature difference d1 between the current base material temperature T and the previous base material temperature Tpr is calculated by the equation (1). d1 = T−Tpr (1)

In step 150, it is determined whether or not the temperature difference d1 is equal to or greater than the limit value D1. Temperature difference d1
Is the temperature at which the base material temperature of the toothed belt 10 has changed in the unit time ΔS, and the change in the temperature gradient of the base material temperature is equal to the change in the temperature difference d1. The limit value D1 is a temperature difference determined from a temperature gradient obtained when the belt life approaches in the test results, and is, for example, 2 ° C. The limit value D1 may be a predetermined multiple of the temperature difference calculated at the time of the previous measurement. That is, assuming that the temperature difference at the previous measurement is d, the limit value D1 is, for example, a value twice (2 × d) the previous temperature difference d.

When it is determined in step 150 that the temperature difference d1 is smaller than the limit value D1, that is, when the temperature gradient of the base material temperature T is not steep and the life of the toothed belt 10 is not approaching yet, step 155 is performed. Is performed. In step 155, the current base material temperature T is set to the previous base material temperature Tpr, and the processing from step 120 to step 150 is executed again. That is, after the elapse of the unit time ΔS, the new substrate temperature is measured as the current substrate temperature T, and the temperature T and the previous substrate temperature Tpr are measured.
Is calculated, and the life of the toothed belt 10 is determined again based on the temperature difference d1. Until it is determined in step 150 that the temperature difference d1 has become equal to or greater than the limit value D1, the processing from step 120 to step 150 is repeated.

When it is determined in step 150 that the temperature difference d1 has become equal to or greater than the limit value D1, that is, when the temperature gradient of the base material temperature T has become steep, step 160
Is performed.

In step 160, a temperature difference (hereinafter referred to as a reference temperature difference) d2 between the current base material temperature T and a reference temperature (for example, the temperature of the cooling water) Tw is calculated by the equation (2). d2 = T−Tw (2)

In step 170, the reference temperature difference d2
Is greater than or equal to a predetermined value D2. This predetermined value D2 is a reference temperature difference (for example, 15 ° C.) when the life of the toothed belt 10 is approaching. When it is determined that the reference temperature difference d2 is smaller than the predetermined value D2, the process of step 155 is executed, and the process of step 120 is executed again. In this case, it is conceivable that an error such as the data m shown in FIG. 4 occurs. That is, since the life of the toothed belt 10 has not yet approached, the processing from step 120 to step 170 is repeated again.

In step 170, the reference temperature difference d2
Is determined to be equal to or greater than the predetermined value D2, in this case, the temperature gradient of the base material temperature T is steep, and the temperature difference between the base material temperature T and the reference temperature Tw is large. It is determined that the life of the belt 10 is approaching.

In step 180, the toothed belt 10
Display device 33 to warn that the life of
Turns on the warning lamp, and this flowchart ends.

According to the above embodiment, while the power transmission device 20 such as an engine is driven, the toothed belt 10 is driven.
The temperature of the raw material rubber (base material temperature) is measured, and the belt life can be easily predicted from a change in the temperature gradient or a temperature difference from a reference temperature (temperature of cooling water or engine oil). Such a belt life prediction device 30 can be actually mounted on the power transmission device 20, and the life of the toothed belt 10 is determined during driving, so that the belt life can be predicted with high accuracy.

[0041]

As described above, according to the present invention, the belt life prediction device is mounted on a power transmission device provided in a vehicle engine or the like, and the back surface temperature of the toothed belt can be measured without performing complicated calculations. By doing so, a highly accurate belt life can be easily predicted.

[Brief description of the drawings]

FIG. 1 is a partially cutaway perspective view showing a toothed belt used in a power transmission device.

FIG. 2 is a longitudinal sectional view of the toothed belt broken in a belt longitudinal direction.

FIG. 3 is a schematic diagram showing a power transmission device equipped with a belt life prediction device according to an embodiment of the present invention.

FIG. 4 is a diagram showing characteristics of a belt base material temperature with respect to a driving time of a power transmission device.

FIG. 5 is a flowchart illustrating a procedure of a life prediction process.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Toothed belt 31 Temperature sensor (temperature detecting means) 30 Belt life predicting device 12 Belt tooth 15 Tooth surface part 16 Back part 21 Driven pulley 22 Drive pulley

Claims (12)

[Claims] 1. A temperature detecting means provided near a toothed belt for detecting a base material temperature which is a temperature of a rubber material constituting the toothed belt; and the toothed belt based on the base material temperature. A belt life predicting device for predicting a belt life at a time when the belt teeth are chipped. 2. The temperature detecting device according to claim 1, wherein the temperature detecting means is provided to face a tooth surface portion of the toothed belt on which belt teeth are formed or a back surface portion on which no belt teeth are formed. A belt life predicting device according to item 1. 3. The temperature detecting means detects the base material temperature while the toothed belt is wound around a driving pulley and a driven pulley, and the toothed belt is driven by the driving pulley. The belt life predicting device according to claim 1, wherein: 4. The belt life according to claim 3, wherein the life prediction means predicts the belt life by detecting a temperature gradient of the base material temperature with respect to a driving time of the toothed belt. Forecasting device. 5. The belt life prediction device according to claim 3, wherein the life prediction unit predicts, when the temperature gradient becomes equal to or more than a limit value, as the belt life. 6. The life prediction means includes: a base material temperature;
The belt life predicting device according to claim 5, wherein the belt life is predicted based on a temperature difference from a reference temperature that is substantially constant with respect to a driving time of the toothed belt. 7. The belt life predicting device according to claim 5, wherein the temperature detecting means is arranged near the driving pulley. 8. A toothed belt is provided in the vicinity of the toothed belt, and detects a base material temperature which is a temperature of a rubber material constituting the toothed belt, and based on the base material temperature, applies a tooth to the belt teeth of the toothed belt. A belt life prediction method for predicting a belt life at which chipping occurs. 9. The method according to claim 8, wherein the toothed belt is wound around a driving pulley and a driven pulley, and the base material temperature is detected while the toothed belt is driven by the driving pulley. The belt life prediction method according to claim 8. 10. The belt life prediction method according to claim 9, wherein the belt life is predicted by detecting a temperature gradient of the base material temperature with respect to a driving time of the toothed belt. 11. The belt life prediction method according to claim 10, wherein the belt life is predicted as when the temperature gradient becomes equal to or more than a limit value. 12. The method according to claim 12, wherein the belt life is the same as the substrate temperature.
12. The belt life prediction method according to claim 11, wherein the prediction is performed based on a temperature difference from a reference temperature that is substantially constant with respect to a driving time of the toothed belt.