JPH07139564A - Abnormality detection device for electromagnetic clutch - Google Patents

Abstract

PURPOSE:To obtain an abnormality detection device with a low cost by detecting a current value to be supplied to an exciting coil, and judging abnormality of an electromagnetic clutch when the detected current value is decreased by a specified value succeedingly for a specified time. CONSTITUTION:In the case that an armature is adsorbed to a rotor by current carrying of an exciting coil 7 of an electromagnetic clutch 1 and a coolant compressor 2 is locked by seizure or the like, frictional surfaces of the armature and the rotor are slid on each other for generating frictional heat. When a peripheral temperature of a stator is increased by the temperature increase of the rotor, resistance of the exciting coil 7 is increased and current of the exciting coil 7 is decreased. When the current value of the exciting coil 7 is detected and its decreasing ratio is a specified value or more succeedingly for a specified time, sliding occurrence is judged between the armature and the rotor. Abnormality is thus judged at the electromagnetic clutch 1. Since a current detection means can be connected to the exciting coil through an electric wiring, processing of the electromagnetic clutch main body is dispensed with, and a manufacturing cost is reduced.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an abnormality detecting device for detecting an abnormality in an electromagnetic clutch.

[0002]

2. Description of the Related Art Conventionally, in a vehicle refrigeration cycle in which a refrigerant compressor is driven by a vehicle running engine via an electromagnetic clutch, various methods have been proposed for preventing the refrigerant compressor from being locked. For example, a rotation speed sensor that detects the shaft rotation speed of the refrigerant compressor is provided, and when the difference between the shaft rotation speed detected by this rotation speed sensor and the engine rotation speed becomes a certain value or more, the electromagnetic clutch is turned off.
By doing so, the lock of the refrigerant compressor is prevented.

Further, when a temperature fuse is connected to the circuit of the electromagnetic clutch and embedded in the stator and the refrigerant compressor locks and the stator becomes an abnormal temperature, the temperature fuse is melted and the energization to the electromagnetic clutch is cut off. It is known how to do it. Furthermore, when slippage occurs between the rotor and armature of the electromagnetic clutch due to the locking of the refrigerant compressor, the magnetic flux in the closed magnetic circuit formed in the electromagnetic clutch changes, so the magnetic flux conversion in this closed magnetic circuit is detected. There is also proposed a method of providing a detection coil for turning off the electromagnetic clutch when a change in the magnetic flux in the closed magnetic circuit is detected by the detection coil (see Japanese Patent Laid-Open Nos. 59-231226 and 62-184232). ).

[0004]

However, in the method using the rotation speed sensor described above, the rotation speed sensor is expensive, and the rotation speed sensor needs to be attached to the refrigerant compressor, resulting in high cost. Further, in the method using the thermal fuse, it is necessary to embed the thermal fuse in the main body of the electromagnetic clutch (stator), so that the cost becomes high, and when the thermal fuse is blown, the electromagnetic clutch cannot be reused, which is very convenient. Is bad.
In the method using the detection coil, the detection coil is expensive and, like the thermal fuse, the detection coil needs to be built in the electromagnetic clutch main body, resulting in high cost. The present invention has been made based on the above circumstances,
An object thereof is to provide a low-cost electromagnetic clutch abnormality detection device.

[0005]

In an electromagnetic clutch, when the excitation coil is energized, the armature frictionally engages with the rotor, and the rotational force of the engine is transmitted to the rotary shaft of the refrigerant compressor. When is locked, slippage occurs between the armature and the rotor and frictional heat is generated. When the ambient temperature (ambient temperature) of the exciting coil rises due to this frictional heat, the resistance value of the exciting coil increases, so that the value of the current flowing through the exciting coil decreases. The present applicant pays attention to this point (the point where the current value flowing in the exciting coil changes depending on the ambient temperature), and it is possible to determine the abnormality of the electromagnetic clutch by detecting the sudden decrease in the current value flowing in the exciting coil. Verified.

Therefore, according to the present invention as set forth in claim 1, as shown in the claim correspondence diagram of FIG. 5, the excitation coil 100 which generates a magnetic force when energized and the rotational force of the rotary power source are rotated. The rotating member is rotatably provided integrally with the rotating shaft of the rotating machine, and frictionally engages with the rotating member when the exciting coil 100 is energized to rotate integrally with the rotating member. Is applied to the electromagnetic clutch 110 having a rotated member for transmitting the rotational force of the rotating shaft to the rotating shaft, and a current value detecting unit 120 for detecting a current value flowing in the exciting coil 100, and the current value detecting unit 12
The technical means includes an abnormality determination means 130 for determining that the electromagnetic clutch is abnormal when the current value detected by 0 continues to decrease for a predetermined time or more by a predetermined value or more.

Further, according to the present invention as set forth in claim 2, as shown in the claim correspondence diagram of FIG. 6, the excitation coil 200 which generates a magnetic force when energized and the rotational force of the rotary power source are rotated. The rotating member is provided so as to be rotatable integrally with the rotating shaft of the rotating machine, and frictionally engages with the rotating member when the exciting coil 200 is energized to rotate integrally with the rotating member. Applied to an electromagnetic clutch 210 having a rotated member that transmits the rotational force of the above to the rotating shaft, and a current value detecting means 220 for detecting a current value flowing in the exciting coil 200, and this current value detecting means 220.
The current decrease rate calculation means 230 for calculating the decrease rate of the current value detected by the current decrease rate, and when the current decrease rate calculated by the current decrease rate calculation means 230 continues to be a predetermined decrease rate or more for a certain period of time, The technical means includes the abnormality determination means 240 for determining that the electromagnetic clutch 210 is abnormal.

[0008]

According to the present invention as set forth in claim 1, the rotating member frictionally engages with the rotating member when the exciting coil is energized to rotate integrally with the rotating member. As a result, the rotational force transmitted from the rotary power source to the rotating member is transmitted to the rotating shaft of the rotating machine via the rotated member, and the rotating shaft rotates. During this operation, if slippage occurs between the rotating member and the rotated member due to abnormal rotation of the rotating machine, the resistance value of the exciting coil increases as the temperature of the rotating member rises due to friction heat, and as a result,
The value of the current flowing through the exciting coil will decrease. Therefore, the value of the current flowing through the exciting coil is detected, and when the detected current value continues to fall for a predetermined time or more and falls below a predetermined value, it is determined that slippage has occurred between the rotating member and the rotated member, and the electromagnetic clutch Is determined to be abnormal.

Further, according to the present invention as set forth in claim 2, when the decrease rate of the detected current value exceeds a predetermined decrease rate for a certain period of time, slippage occurs between the rotating member and the rotated member. If it is occurring, it is determined that the electromagnetic clutch is abnormal.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of an electromagnetic clutch abnormality detecting device of the present invention will be described below with reference to FIGS. 1 is an electric circuit diagram including an abnormality detecting device for an electromagnetic clutch, and FIG. 2 is a sectional view of the electromagnetic clutch. The electromagnetic clutch 1 is interposed between a running engine of a vehicle (not shown, a rotary power source of the present invention) and a refrigerant compressor 2 of a refrigeration cycle (a rotary machine of the present invention), and if necessary, the engine. It transmits a rotational force to the refrigerant compressor 2, and is composed of a stator 3, a rotor 4, an armature 5, a hub assembly 6, and the like.

The stator 3 is composed of an exciting coil 7 which generates a magnetic force when energized and a stator housing 8 which supports the exciting coil 7. The exciting coil 7 is formed by winding a coil wire around a resin spool 9, and is housed in a stator housing 8 and then fixed by a molding resin 10. The stator housing 8 is made of a magnetic material such as iron, and the rotor 4 and the armature 5 are also magnetic materials.
Together with this, the magnetic path of the exciting coil 7 is formed.

The rotor 4 (rotating member of the present invention) is rotatably supported by the housing 2a of the refrigerant compressor 2 via a bearing 11 arranged on the inner periphery of the rotor 4 and a crank pulley (not shown) of the engine. Rotational power of the engine is transmitted via a belt (not shown) that is wound around a pulley 12 provided on the outer circumference of the rotor 4. The rotor 4 has one axial end surface (the left end surface in FIG. 2) as a friction surface.

The armature 5 has a friction surface facing the friction surface of the rotor 4, and when the energization of the exciting coil 7 is stopped, a hub assembly 6 is provided so that a predetermined gap is maintained between the friction surfaces. Supported by.

The hub assembly 6 includes an outer hub 14 fixed to the armature 5 with rivets 13, an inner hub 15 fixed to the rotary shaft 2b of the refrigerant compressor 2 on the inner peripheral side of the outer hub 14, and the outer hub 14 and the inner hub 1.
It is composed of a rubber hub 16 for connecting with 5. The rotated member of the present invention comprises the armature 5 and the hub assembly 6.

In this electromagnetic clutch 1, as shown in FIG. 1, both ends of the exciting coil 7 are connected to the negative lead wire 17 and the positive lead wire 18 of the stator 3, respectively, and the negative lead wire 17 compresses the refrigerant. The positive side lead wire 18 is fixed to the machine 2 and grounded, and is connected to the air conditioner control device 21 via the current detection device 19 and the air conditioner relay 20.

The current detecting device 19 includes the positive lead wire 1
8 is interposed between the air conditioner relay 20 and the air conditioner relay 20 to detect the current value flowing through the exciting coil 7 by, for example, a shunt resistor, and outputs a signal corresponding to the detected current value to the air conditioner control device 21.

The air conditioner control device 21 has a built-in microcomputer (not shown), and when an air conditioner switch 22 provided on a control panel (not shown) in the vehicle compartment is turned on, a vehicle battery (not shown) is installed. It operates by receiving more power. The air conditioner control device 21 controls ON / OFF of the electromagnetic clutch 1 via the air conditioner relay 20, and determines whether the electromagnetic clutch 1 is abnormal based on the current value detected by the current detection device 19. When the determination is made and it is determined to be abnormal, the power supply to the electromagnetic clutch 1 (excitation coil 7) is stopped via the air conditioner relay 20.

Next, the operation of the electromagnetic clutch 1 will be described.
When the energization of the exciting coil 7 is stopped, the armature 5 is held at a position distant from the rotor 4, so that the rotational force transmitted from the engine to the rotor 4 via the rivet 13 is not transmitted to the armature 5. , Therefore rotor 4
Only the bearing 11 spins idle.

Excitation coil 7 via air conditioner relay 20
Is energized, the magnetic force generated by the exciting coil 7 causes
The armature 5 is attracted to the rotor 4 side against the elastic force of the rubber hub 16. As a result, the friction surface of the armature 5 and the friction surface of the rotor 4 are in close contact with each other and frictionally engage with each other, so that the rotational force of the rotor 4 is transmitted to the rotary shaft 2b of the refrigerant compressor 2 via the armature 5 and the hub assembly 6. Then, the refrigerant compressor 2 is driven.

Next, the operation of this embodiment for determining the abnormality of the electromagnetic clutch 1 will be described with reference to the flow chart shown in FIG. When the exciting coil 7 is energized, that is, the armature 5
When the refrigerant is adsorbed on the rotor 4, the refrigerant compressor 2
When is locked by baking or the like, frictional heat is generated by friction between the friction surfaces of the armature 5 and the rotor 4. When the ambient temperature around the stator 3 rises due to the temperature rise of the rotor 4 due to this frictional heat, the resistance value of the exciting coil 7 increases, and the current value flowing through the exciting coil 7 decreases. Therefore, the value of the current flowing through the exciting coil 7 is detected, and when the rate of decrease of the current value becomes equal to or higher than a predetermined rate of decrease, it is determined that slippage has occurred between the armature 5 and the rotor 4, and the electromagnetic clutch 1 Can be judged to be abnormal.

First, the value of the current flowing through the exciting coil 7 is detected by the current detecting device 19 (step S1). Then, the reduction rate of the current value detected by the current detection device 19 is calculated (step S2, current reduction rate calculation means of the present invention). Then, it is determined whether or not the electromagnetic clutch 1 is abnormal based on the current reduction rate calculated in step S2 (step S3, abnormality determination means of the present invention). The abnormality determination of the electromagnetic clutch 1 is performed by the current decrease rate calculation means (I ₂ / t ₂ ) as described above.
Is determined to be abnormal when the decrease rate (I ₁ / t ₁ ) or more continues for a certain period of time (see FIG. 4).

If the decision result in the step S3 is NO, that is, if there is no abnormality, the processes in and after the step S1 are repeated. If the decision result in the step S3 is YES,
That is, when it is determined that the electromagnetic clutch 1 is abnormal, the air conditioner relay 20 is activated (step S
4), stop energizing the electromagnetic clutch 1 (excitation coil 7) (step S5).

As described above, in this embodiment, the exciting coil 7
The value of the current flowing in the electromagnetic clutch 1 is detected by the current detection device 19, and the electromagnetic clutch 1 is detected based on the detected reduction rate of the current value.
When it is determined that is abnormal, the electromagnetic clutch 1 is immediately turned off, so that the electromagnetic clutch 1 can be protected and the belt can be prevented from being broken.

[Modification] In the present embodiment, it is determined that the electromagnetic clutch is abnormal when the current decrease rate calculated by the current decrease rate calculating unit is equal to or higher than a predetermined decrease rate for a certain period of time. It may be determined that the electromagnetic clutch is abnormal when the value of the current flowing through the exciting coil is reduced by a predetermined value or more continuously for a certain period of time.

In this embodiment, an example in which the ambient temperature of the stator 3 rises due to the frictional heat generated by the slip between the armature 5 of the electromagnetic clutch 1 and the rotor 4 as the refrigerant compressor locks is shown. When the temperature of the refrigerant discharged from the machine 2 rises, the temperature of the housing 2a of the refrigerant compressor 2 rises and the temperature of the stator 3 of the electromagnetic clutch 1 rises due to the heat transfer from the housing 2a. When the reduction rate of the flowing current value becomes equal to or higher than a predetermined reduction rate, or as shown in the above modification, the electromagnetic clutch 1 is operated when the current value flowing in the exciting coil 7 continues to decrease for a predetermined time or more. By turning it off, it is possible to prevent the abnormality of the refrigerant discharged from the refrigerant compressor 2.

When determining the abnormality of the electromagnetic clutch 1,
Malfunction prevention control may be executed to prevent malfunction due to exhaustion of the battery or the like. This malfunction prevention control is performed before the abnormality determination based on the current change rate (step S3).
For example, it is determined whether or not the voltage value has changed. If the voltage value has changed, there is a risk of malfunction due to exhaustion of the battery or the like. Therefore, the abnormality determination (step S3) is not performed, and the voltage value is If it does not change, the abnormality determination (step S3) is performed as it is.

In this embodiment, the current detecting device 1 is provided between the positive side lead wire 18 of the stator 3 and the air conditioner relay 20.
Although 9 is connected, a current detection element for detecting the current flowing through the exciting coil 7 may be embedded at a position where the temperature change of the stator 3 is easily detected (in the vicinity of the friction surface of the rotor 4). Thereby, the detection accuracy of the current flowing through the exciting coil 7 can be improved.

[0028]

According to the present invention, the current flowing through the exciting coil is detected by the current value detecting means, and the abnormality of the electromagnetic clutch can be determined based on the detected decrease or decrease rate of the current value. Since the current value detecting means can be used by connecting it to the exciting coil by electric wiring, the electromagnetic clutch main body does not need to be processed, and the cost can be reduced as compared with the prior art. In addition, since it is determined that the electromagnetic clutch is abnormal when the decrease of the current value above the predetermined value or the increase of the current decrease rate above the predetermined decrease rate continues for a certain period of time, It is possible to prevent erroneous determination due to decrease.

[Brief description of drawings]

FIG. 1 is an electric circuit diagram including an abnormality detection device for an electromagnetic clutch.

FIG. 2 is a sectional view of an electromagnetic clutch.

FIG. 3 is a flowchart showing the operation of this embodiment.

FIG. 4 is a graph showing changes in the value of current flowing through an exciting coil.

FIG. 5 is a diagram corresponding to the claim of claim 1.

FIG. 6 is a diagram corresponding to the claim of claim 2;

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Electromagnetic clutch 2 Refrigerant compressor (rotating machine) 2b Rotating shaft 4 Rotor (rotating member) 5 Armature (rotated member) 6 Hub assembly (rotated member) 7 Excitation coil 19 Current detection device (current value detection means) 21 Air conditioner control Device (current reduction rate calculation means, abnormality determination means)

Claims (2)

[Claims] 1. An excitation coil that generates a magnetic force when energized, a rotating member that rotates by receiving the rotational force of a rotary power source, and a rotating shaft of a rotating machine that are integrally rotatably provided. It is applied to an electromagnetic clutch provided with a rotated member that frictionally engages with the rotating member when the coil is energized and rotates integrally with the rotating member, thereby transmitting the rotational force of the rotating member to the rotating shaft. A) current value detecting means for detecting a current value flowing in the exciting coil; and b) when the current value detected by the current value detecting means continues to fall for a predetermined time or more and falls below a predetermined value. An abnormality detecting device for an electromagnetic clutch, comprising: abnormality determining means for determining an abnormality. 2. An exciting coil that generates a magnetic force by being energized, a rotating member that rotates by receiving a rotating force of a rotary power source, and a rotating shaft of a rotating machine that are integrally rotatable and are provided with the exciting coil. It is applied to an electromagnetic clutch provided with a rotated member that frictionally engages with the rotating member when the coil is energized and rotates integrally with the rotating member, thereby transmitting the rotational force of the rotating member to the rotating shaft. A) current value detecting means for detecting a current value flowing in the exciting coil; b) current decrease rate calculating means for calculating a decrease rate of the current value detected by the current value detecting means; and c) this current. Abnormality detection device for electromagnetic clutch, comprising abnormality determination means for determining abnormality of the electromagnetic clutch when the current reduction rate calculated by the reduction rate calculation means is equal to or higher than a predetermined reduction rate for a certain period of time. .