JP2021050711A - Fan belt abnormality detection device - Google Patents

Abstract

To immediately detect abnormality of a fan belt.SOLUTION: An abnormality detection device of a fan belt 8 stretched between a crank pulley 1 and a fan pulley 4 includes: a crank speed sensor 31; a fan speed sensor 32; and a detection unit 100 detecting abnormality of the fan belt on the basis of rotating speeds detected by these sensors. The detection unit stores a map or a function for defining a relationship between a rotating speed of a crank shaft and a rotating speed of a fan in advance, and compares a threshold value determined from the map or the function with a detection value of the rotating speed of the fan to detect the abnormality of the fan belt. A plurality of threshold values are set to the same rotating speed of the crank shaft, and the detection unit discriminates the abnormality of the fan belt by comparing the plurality of threshold values with the detection value of the rotating speed of the fan.SELECTED DRAWING: Figure 1

Description

The present disclosure relates to a fan belt abnormality detecting device for detecting an abnormality of a fan belt of an internal combustion engine.

Generally, in an internal combustion engine in which a fan is arranged offset from a crankshaft, a fan belt is hung between a crank pulley attached to the crankshaft and a fan pulley attached to the fan.

Japanese Unexamined Patent Publication No. 2018-200005

The fan belt gradually deteriorates with use. When the fan belt deteriorates, the driving force of the crankshaft is not sufficiently transmitted to the fan, the rotation speed of the fan decreases, and for example, the amount of air passing through the radiator becomes insufficient.

Conventionally, an abnormality in a fan belt has been indirectly detected by detecting an engine abnormality due to a malfunction of an auxiliary machine driven by the fan belt at the same time. For example, when the water pump is driven by the fan belt at the same time, the water temperature rises due to the malfunction of the water pump. This rise in water temperature was regarded as an engine abnormality, and inspection and maintenance were performed. As a result, an abnormality in the fan belt was detected.

However, in this case, there is a time lag between the occurrence of the fan belt abnormality and the occurrence of the engine abnormality, and the result may already be too late at the time of the engine abnormality occurrence.

Therefore, the present disclosure was devised in view of such circumstances, and an object of the present disclosure is to provide a fan belt abnormality detecting device capable of immediately detecting an abnormality of a fan belt.

According to one aspect of the present disclosure
A fan belt abnormality detection device for detecting abnormalities in the fan belt of an internal combustion engine.
The internal combustion engine
With the crank pulley attached to the crankshaft,
The fan pulley attached to the fan and
With the fan belt hung between the crank pulley and the fan pulley,
With
The fan belt abnormality detection device is
A crank speed sensor that detects the rotational speed of the crankshaft, and
A fan speed sensor that detects the rotation speed of the fan and
A detection unit configured to detect an abnormality in the fan belt based on the rotation speed detected by the crank speed sensor and the fan speed sensor, respectively.
With
The detection unit stores in advance a map or function that defines the relationship between the rotation speed of the crankshaft and the threshold value of the rotation speed of the fan, and the threshold value obtained from the map or function and the rotation speed of the fan. The abnormality of the fan belt is detected by comparing with the detected value of
A plurality of the threshold values are set for the same rotation speed of the crankshaft, and the detection unit compares the plurality of threshold values with the detected values of the rotation speed of the fan to determine the type of abnormality of the fan belt. A fan belt abnormality detection device characterized by discriminating is provided.

Preferably, as the threshold value, a first threshold value, a second threshold value, and a third threshold value are set in order from the highest value.
The detection unit is
When the detected value of the rotation speed of the fan is equal to or less than the first threshold value and larger than the second threshold value, it is determined that the fan belt is slipping abnormally.
When the detected value of the rotation speed of the fan is equal to or less than the second threshold value and larger than the third threshold value, it is determined that the fan belt is worn abnormally.
When the detected value of the rotation speed of the fan is equal to or less than the third threshold value, it is determined that the fan belt is broken.

According to the present disclosure, an abnormality of the fan belt can be detected immediately.

It is a schematic diagram which shows the structure of this embodiment. It is a figure which shows a map. It is a flowchart of an abnormality detection routine. It is a flowchart of another abnormality detection routine.

Hereinafter, embodiments of the present disclosure will be described with reference to the accompanying drawings. It should be noted that the present disclosure is not limited to the following embodiments.

FIG. 1 schematically shows the configuration of this embodiment. The internal combustion engine of the present embodiment is mounted on a vehicle, the vehicle is a truck, and the internal combustion engine (also referred to as an engine) is a diesel engine. However, the type and application of the internal combustion engine are not particularly limited, and for example, the engine may be a gasoline engine. The engine may be mounted on a moving body other than a vehicle, for example, a ship, a construction machine, or an industrial machine. Further, the engine does not have to be mounted on a moving body, and may be a stationary engine.

In the present embodiment, the engine is vertically installed on the vehicle, and the front side in the paper thickness direction in the figure is the front side of the vehicle. Each direction of front, back, left, right, up and down is as shown in the figure.

On the front surface of the engine, a crank pulley 1 is fixedly attached to the crankshaft 20. Reference numeral C1 represents the center of the crank pulley 1. A water pump 2 and a generator (ACG: AC Generator) 3 are fixedly attached to the front surface of the engine. A fan pulley 4, a fan clutch 5, and a fan (only the fan blade is shown in the figure) 6 are coaxially attached to the input shaft of the water pump 2 in this order from the rear. Reference numeral C4 represents the center of the fan pulley 4. A generator pulley 7 is attached to the input shaft of the generator 3. Reference numeral C7 represents the center of the generator pulley 7.

A fan belt 8 is hung on the crank pulley 1, the fan pulley 4, and the generator pulley 7. As a result, the water pump 2, the fan 6, and the generator 3 are driven by the crankshaft 20 via the common fan belt 8. The water pump 2, the fan 6, and the generator 3 are arranged offset with respect to the crankshaft 20.

The fan 6 is arranged close to the rear of the radiator to generate wind that passes through the radiator as it rotates to suck air.

In the case of the present embodiment, the fan clutch 5 uses an electronically controlled fan clutch whose fastening force can be controlled by an electronic control unit (called an ECU (Electronic Control Unit)) 100. The structure is arbitrary, but for example, the fan clutch 5 includes a fluid coupling capable of connecting and disconnecting an input unit and an output unit, and a valve for adjusting the fluid supply state to the fluid coupling, and the valve is opened. By controlling the state by the ECU 100, the clutch engagement rate can be arbitrarily variably controlled from 0% corresponding to complete disconnection to 100% equivalent to complete contact. The fan pulley 4 is fixed to the input portion of the fan clutch 5, and the fan 6 is fixed to the output portion of the fan clutch 5.

The ECU 100 has a target value of an optimum clutch engagement rate based on information on the operating state of the engine and the vehicle obtained based on outputs from various sensors (not shown), for example, engine water temperature, transmission oil temperature, outside temperature, vehicle speed, and the like. Is calculated, and the valve open state is controlled so that the actual clutch engagement rate becomes the target value. As a result, it is possible to obtain the optimum rotation speed of the fan 6 according to the operating conditions of the engine, the vehicle, and the like.

As another electronically controlled fan clutch, an electromagnetic clutch or the like whose fastening force can be controlled by an electromagnetic force can also be used.

In such a configuration, the fan belt abnormality detection device includes a crank speed sensor 31 that detects the rotation speed (also referred to as crank speed) of the crankshaft 20 and a fan speed sensor 32 that detects the rotation speed (also referred to as fan speed) of the fan 6. A detection unit configured to detect an abnormality in the fan belt 8 based on the rotation speeds detected by the crank speed sensor 31 and the fan speed sensor 32, respectively. In the case of this embodiment, the detection unit is composed of the ECU 100. The ECU 100 also controls the entire engine. The crank speed sensor 31 and the fan speed sensor 32 are composed of, for example, well-known non-contact sensors arranged in close proximity to the crankshaft 20 and the fan 6, respectively. Since the rotation speed is represented by the rotation speed (rpm) per minute, the crank speed and the fan speed are also hereinafter referred to as the crank rotation speed and the fan rotation speed. Crank rotation speed is synonymous with engine rotation speed.

Hereinafter, the abnormality detection method will be specifically described. The ECU 100 previously provides a map (may be a function; the same applies hereinafter) as shown in FIG. 2, which defines the relationship between the crank rotation speed Ne and the threshold values Nfa, Nfb, Nfc (generally referred to as Nf) of the fan rotation speed Nf. I remember. Then, the ECU 100 compares the threshold value Nf obtained from the map with the detected value of the fan rotation speed Nf to detect an abnormality in the fan belt 8.

In particular, a plurality of threshold values Nf are set for the same crank rotation speed Ne, and in this embodiment, three threshold values such as Nfa, Nfb, and Nfc are set in descending order. The ECU 100 compares these plurality of threshold values Nfa, Nfb, Nfc with the detected values of the fan rotation speed Nf to determine the type of abnormality in the fan belt 8.

Here, it is assumed that the fan clutch 5 is in a completely connected state, there is no slippage thereof, and the fan pulley 4 and the fan 6 are integrally rotated at the same rotation speed.

As shown in FIG. 2, assuming that the fan belt 8 does not slip, a proportional relationship as shown by the line s holds between the crank rotation speed Ne and the fan rotation speed Nf. Here, Nei is a predetermined idle speed (for example, 500 rpm), and Ncm is a predetermined maximum speed (for example, 2000 rpm). On the line s, the fan speed when the idle speed Nei is Nfi is Nfi, which idles the pulley ratio K (crank pulley diameter / fan pulley diameter, for example 1.5) of the crank pulley 1 and the fan pulley 4. It is a value obtained by multiplying the number of revolutions Nei (Nfi = K × Nei). Similarly, when the maximum rotation speed is Nem, the fan rotation speed is Nfm.

When the fan belt 8 is new, the fan rotation speed Nf is approximately located on the line s. However, if the fan belt 8 deteriorates with use, the fan belt 8 slides on the pulley, so that the fan rotation speed Nf is lower than the line s.

The line a representing the threshold value Nfa is a line connecting the maximum values of the fan rotation speed Nf when the slip of the fan belt 8 becomes unacceptably large. That is, it is a line for distinguishing between normal and abnormal of the fan belt 8. As can be seen, in the rotation speed range ΔNe from the idle rotation speed Nei to a predetermined first rotation speed Nej higher than that, the line a drops more than the proportional line s. The reason is that the engine tends to be operated with a high load in such a low speed range ΔNe, and the fan belt 8 becomes slippery. As is generally seen, when the engine is cold before the warm-up is completed, the fan belt 8 is slippery in such a rotation speed range ΔNe, including during the first idle operation, and the belt squeal due to this is likely to occur.

On the other hand, when the first rotation speed Nej is exceeded, the line a rapidly approaches the proportional line s and eventually rises in parallel with the proportional line s. This is because when the deterioration of the fan belt 8 is slight, the fan belt 8 is less likely to slip in the high rotation speed range.

If the fan rotation speed Nf detected at a specific crank rotation speed Ne is equal to or less than the threshold value Nfa corresponding to the crank rotation speed Ne, there is a possibility that a slip abnormality has occurred in which the fan belt 8 slips unacceptably. It is judged that there is. On the contrary, when the detected fan rotation speed Nf is larger than the threshold value Nfa, the fan belt 8 is determined to be normal.

The line a is located below the proportional line s (the fan rotation speed lowering side) by a predetermined margin ΔNf. This is because, for example, a slight belt slip caused by variations in the product and operating conditions, which may occur even in a normal fan belt 8, is not erroneously determined as an abnormality.

Next, the line b representing the threshold value Nfb is a line for distinguishing between the slip abnormality and the wear abnormality in which the wear of the fan belt 8 is unacceptably large. Wear abnormalities are more severe than slip abnormalities. The line b is the same as the line a in a rotation speed region of a predetermined second rotation speed Nek or less, which is slightly higher than the first rotation speed Nej. However, the line b gradually deviates from the line a to the lower side as it goes from the second rotation speed Nek to the high rotation side. This is because if the fan belt 8 is heavily worn, the fan belt 8 is no longer slippery even in the high rotation range.

If the fan rotation speed Nf detected at a specific crank rotation speed Ne is equal to or less than the threshold value Nfb corresponding to the crank rotation speed Ne, it is determined that the fan belt 8 may have a wear abnormality. To. On the other hand, when the detected fan rotation speed Nf is equal to or less than the threshold value Nfa and larger than the threshold value Nfb, the fan belt 8 is definitively determined to be slip abnormal.

Next, the line c representing the threshold value Nfc is a line for distinguishing the above-mentioned slip abnormality and wear abnormality from the fracture abnormality in which the fan belt 8 is broken or divided. Fracture abnormalities are more severe than wear abnormalities. The line c is located far below the lines a and b in all rotation speed regions. When the fan belt 8 breaks, the fan 6 is no longer driven by the fan belt 8, but the fan 6 may rotate due to running wind or the like. In consideration of this, the threshold value Nfc is set to a value of the fan rotation speed Nf slightly larger than zero.

When the fan rotation speed Nf detected at a specific crank rotation speed Ne is equal to or less than the threshold value Nfc corresponding to the crank rotation speed Ne, the fan belt 8 is definitively determined to be a break abnormality. On the other hand, when the detected fan rotation speed Nf is equal to or less than the threshold value Nfb and larger than the threshold value Nfc, the fan belt 8 is deterministically determined to be wear abnormality.

As described above, according to the present embodiment, since the abnormality of the fan belt 8 is detected by comparing the threshold value Nf obtained from the map with the detected value of the fan rotation speed Nf, the abnormality of the fan belt 8 is immediately detected. be able to. Moreover, in order to determine the type of abnormality in the fan belt 8 by comparing the plurality of threshold values Nfa, Nfb, Nfc with the detected values of the fan rotation speed Nf, the type of abnormality can also be identified, and subsequent inspection and maintenance can be performed. It can be facilitated and appropriate measures can be taken according to the type of anomaly.

In the map, the region above the line a (the fan rotation speed increase side) is defined as the normal region As, the region sandwiched between the lines a and b is designated as the slip abnormality region Aa, and the region is sandwiched between the lines b and c. The region is defined as an abnormal wear region Ab, and the region below the line c is defined as an abnormal fracture region Ac. Normal, slip abnormality, wear abnormality, and break abnormality can be discriminated depending on which region the combination of the detected values of the crank rotation speed Ne and the fan rotation speed Nf belongs to.

Next, the abnormality detection routine of the present embodiment will be described with reference to FIGS. 3 and 4. The illustrated routine is repeatedly executed by the ECU 100 every predetermined calculation cycle τ (for example, 10 msec).

As shown in FIG. 3, in step S101, the ECU 100 acquires the value of the crank rotation speed Ne detected by the crank speed sensor 31.

In step S102, the ECU 100 determines whether or not the acquired crank rotation speed Ne is a value within the rotation speed range ΔNe from the idle rotation speed Nei to the first rotation speed Nej, that is, whether or not Nei ≦ Ne ≦ Nej. .. If the crank rotation speed Ne is a value within the rotation speed range ΔNe, the process proceeds to step S103 to continue the detection process. If the crank rotation speed Ne is not a value within the rotation speed range ΔNe, the routine is terminated and the detection process is terminated.

As described with reference to FIG. 2, in the rotation speed range ΔNe, the line a deviates more than the proportional line s, so that it is easy to distinguish between normal and abnormal. Therefore, the detection accuracy can be improved by limiting the abnormality detection to the rotation speed range ΔNe.

In step S103, the ECU 100 completely engages the fan clutch 5. As a result, the slip of the fan clutch 5 can be eliminated, and the fan rotation speed can be prevented from being lowered due to the slip, and erroneous detection can be prevented.

In step S104, the ECU 100 acquires the fan speed Nf detected by the fan speed sensor 32.

In step S105, the ECU 100 calculates the highest threshold value Nfa corresponding to the acquired crank rotation speed Ne from the map of FIG. Then, the acquired fan rotation speed Nf is compared with the calculated threshold value Nfa.

When the fan rotation speed Nf is larger than the threshold value Nfa, the ECU 100 substantially determines that the fan belt 8 is normal, and ends the routine. On the other hand, when the fan rotation speed Nf is equal to or less than the threshold value Nfa, the ECU 100 proceeds to step S106.

In step S106, the ECU 100 calculates the lowest threshold value Nfc corresponding to the acquired crank rotation speed Ne from the map of FIG. Then, the acquired fan rotation speed Nf is compared with the calculated threshold value Nfc.

When the fan rotation speed Nf is equal to or less than the threshold value Nfc, the ECU 100 proceeds to step S107 and determines that a breaking abnormality of the fan belt 8 has occurred. Then, the process proceeds to step S108, and the strong warning, which is the strongest warning, is given, and the engine is controlled in the fail-safe mode. That is, the warning device of the vehicle is activated, and for example, the driver of the vehicle is notified by display, voice, or the like that an abnormality in the breakage of the fan belt 8 has occurred, that the vehicle is to be repaired immediately, and the like. Then, the engine speed, fuel injection amount, and the like are limited, high-load operation of the engine is prohibited, and the vehicle is urged to evacuate.

On the other hand, when the fan rotation speed Nf is larger than the threshold value Nfc, the ECU 100 proceeds to step S109 to turn on the temporary abnormality flag. At this point, it is possible to identify whether either slip abnormality or wear abnormality has occurred, but it is not possible to specify which of them has occurred. Therefore, the temporary abnormality flag is turned on, and the type of abnormality is specified by another routine shown in FIG.

Next, another routine shown in FIG. 4 will be described. In step S201, the ECU 100 determines whether or not the temporary abnormality flag is on. If it is not on (if it is off), the routine is terminated, and if it is on, the process proceeds to step S202.

In step S202, the ECU 100 acquires the value of the crank rotation speed Ne detected by the crank speed sensor 31.

In step S203, the ECU 100 determines whether or not the acquired crank rotation speed Ne is equal to or higher than the predetermined rotation speed Nek shown in FIG. If the crank rotation speed Ne is less than the predetermined rotation speed Nek, the routine is terminated, and if the crank rotation speed Ne is equal to or more than the predetermined rotation speed Nek, the process proceeds to step S204 in order to discriminate between slip abnormality and wear abnormality.

In step S204, the ECU 100 completely engages the fan clutch 5.

In step S205, the ECU 100 acquires the fan speed Nf detected by the fan speed sensor 32.

In step S206, the ECU 100 calculates an intermediate size threshold value Nfb corresponding to the acquired crank rotation speed Ne from the map of FIG. Then, the acquired fan rotation speed Nf is compared with the calculated threshold value Nfb.

When the fan rotation speed Nf is equal to or less than the threshold value Nfb, the ECU 100 proceeds to step S207 and determines that a wear abnormality of the fan belt 8 has occurred. Then, the process proceeds to step S208, and a medium warning, which is a warning having moderate intensity, is performed. That is, the warning device of the vehicle is activated to notify the driver of the vehicle by display, voice, or the like that, for example, an abnormality in wear of the fan belt 8 has occurred, the vehicle should be repaired as soon as possible, and the like.

On the other hand, when the fan rotation speed Nf is larger than the threshold value Nfb, the ECU 100 proceeds to step S209 and determines that a slip abnormality of the fan belt 8 has occurred. Then, the process proceeds to step S210 to give a weak warning, which is the weakest warning. That is, the warning device of the vehicle is activated, and the driver of the vehicle is notified by a display or the like that, for example, a slip abnormality of the fan belt 8 has occurred, the fan belt 8 is to be inspected at the next inspection, and the like.

As understood in the above description, the thresholds Nfa, Nfb, and Nfc of the present embodiment correspond to the first, second, and third thresholds in the claims, respectively.

Although the embodiments of the present disclosure have been described in detail above, various other embodiments and modifications of the present disclosure can be considered.

(1) For example, in the routine of FIG. 3, the crank rotation speed Ne for detecting an abnormality does not have to be limited to the rotation speed range ΔNe. That is, step S102 may be omitted.

(2) In the routines of FIGS. 3 and 4, the fan clutch 5 is completely engaged when the fan rotation speed Nf is acquired, but the fan clutch 5 does not necessarily have to be completely engaged. In this case, it is preferable to correct the threshold value Nf according to the engagement rate of the fan clutch 5. That is, it is preferable that the lower the engagement rate of the fan clutch 5 is, the more the threshold value Nf is corrected to the decreasing side.

(3) The fan clutch does not have to be an electronically controlled type, and may be an intake air temperature sensitive type clutch using a more general bimetal. Alternatively, the fan clutch may be omitted and the fan and the fan pulley may be directly connected.

The embodiments of the present disclosure are not limited to the above-described embodiments, and all modifications, applications, and equivalents included in the ideas of the present disclosure defined by the claims are included in the present disclosure. Therefore, the present disclosure should not be construed in a limited manner and may be applied to any other technique belonging within the scope of the ideas of the present disclosure.

1 Crank pulley 4 Fan pulley 8 Fan belt 31 Crank speed sensor 32 Fan speed sensor 100 Electronic control unit

Claims (2)

A fan belt abnormality detection device for detecting abnormalities in the fan belt of an internal combustion engine.
The internal combustion engine
With the crank pulley attached to the crankshaft,
The fan pulley attached to the fan and
With the fan belt hung between the crank pulley and the fan pulley,
With
The fan belt abnormality detection device is
A crank speed sensor that detects the rotational speed of the crankshaft, and
A fan speed sensor that detects the rotation speed of the fan and
A detection unit configured to detect an abnormality in the fan belt based on the rotation speed detected by the crank speed sensor and the fan speed sensor, respectively.
With
The detection unit stores in advance a map or function that defines the relationship between the rotation speed of the crankshaft and the threshold value of the rotation speed of the fan, and the threshold value obtained from the map or function and the rotation speed of the fan. The abnormality of the fan belt is detected by comparing with the detected value of
A plurality of the threshold values are set for the same rotation speed of the crankshaft, and the detection unit compares the plurality of threshold values with the detected values of the rotation speed of the fan to determine the type of abnormality of the fan belt. A fan belt abnormality detection device characterized by discriminating. As the threshold value, a first threshold value, a second threshold value, and a third threshold value are set in order from the highest value.
The detection unit is
When the detected value of the rotation speed of the fan is equal to or less than the first threshold value and larger than the second threshold value, it is determined that the fan belt is slipping abnormally.
When the detected value of the rotation speed of the fan is equal to or less than the second threshold value and larger than the third threshold value, it is determined that the fan belt is worn abnormally.
The fan belt abnormality detection device according to claim 1, wherein when the detection value of the rotation speed of the fan is equal to or less than the third threshold value, it is determined that the fan belt is broken.

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