JP3027788B2 - Temperature detection method of electromagnetic retarder - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for detecting the temperature of an electromagnetic retarder, in particular, when a thermistor is used as a heat-sensitive element in performing thermal protection of the retarder, the thermal protection circuit is activated after a predetermined time has elapsed after the operation of the retarder. The present invention relates to an exciting coil type retarder for performing substantial temperature detection, that is, a temperature detection method of an electromagnetic type retarder.

[0002]

2. Description of the Related Art FIG. 10 is a circuit diagram of a conventional exciting coil type retarder. In the figure, 1 is a transistor, 2 is an exciting coil, 3 is a switching element, 4 is a dead time circuit, 5 is a thermistor, 6 is a power supply, 7 is a triangular wave generation circuit, 8 is a comparator, 9 is an AND circuit, 10
Is a comparator, 11 is a deviation amplifier, 12 is a variable resistor,
Reference numeral 13 denotes a resistor.

As shown in FIG. 2, the exciting coil 2 has a magnetic pole core 1.
4 are wound around the plurality of magnetic poles 15 provided. Depending on the signal output from the dead time circuit 4, for example, IGBT (insulated gate bipolar transistor), FE
When the switching element 3 such as a T-transistor is turned on, an exciting current flows through the exciting coil 2 and the magnetic poles 15 alternately change to N.
It is magnetized into a pole and an S pole.

In FIG. 2, the magnetic pole core 14 and the vortex cylinder 16 are illustrated separately, but the magnetic pole core 14 is
6, the magnetic pole core 14 and the swirl cylinder 16 rotate relatively.

The transistor 1, which also functions as a retarder operation switch, is controlled to be turned off when the retarder operates and turned on when the retarder stops. When the transistor 1 of the retarder operation switch is turned off, the inverting input terminal of the comparator 8 is set to the ground level as shown in FIG. 11A, and the comparator 8 is turned on. The ON signal of the comparator 8 (duty ratio 100% described later)
(PWM signal) turns on the switching element 3 via the AND circuit 9. Accordingly, an exciting current flows through the exciting coil 2, and the magnetic poles 15 are alternately magnetized into N poles and S poles as described above. Due to this magnetization, an eddy current is generated on the magnetic pole facing surface 16-1 of the eddy current cylinder 16 which is rotated by the output shaft of the transmission, and the direction of rotation of the eddy current cylinder 16 is reversed between the eddy current and the magnetic field generated by the exciting coil 2. A directional electromagnetic force is generated which exerts a braking effect on the rotational movement of the swirl cylinder 16.

In the above description, the swirl cylinder 16 is a rotor and the magnetic pole core 14 is a stator. However, the braking function works in exactly the same manner when the swirl cylinder 16 is a stator and the magnetic pole core 14 is a rotor.

A heat sensitive element, for example, a thermistor 5 is attached to the exciting coil 2 and detects a temperature rise of the exciting coil 2. When the temperature of the exciting coil 2 becomes equal to or higher than the protection temperature set in advance by the variable resistor 12, the transistor 1 of the retarder operation switch is turned on via the deviation amplifier 11 and the comparator 10, although not clearly shown in FIG. Is controlled, and the inverting input terminal of the comparator 8 is
The level is as high as 1B. Therefore, the comparator 8 is turned off, the switching element 3 is turned off, and the exciting current flowing through the exciting coil 2 is cut off, thereby preventing the temperature of the exciting coil 2 from rising.

[0010] The temperature protection of the retarder will be further described. During the operation of the retarder, the temperature of the eddy current cylinder 16 becomes high due to the eddy current loss, and the magnetic pole core 14 and the exciting coil 2 are thermally damaged by radiant heat from the eddy current cylinder 16. Since there is a possibility that the Joule heat of the exciting coil 2 may cause its burning, the temperature is detected by the thermistor 5 as described above, and the temperature protection of the retarder, that is, the thermal protection is provided.

[0009]

The distance between the mounting position of the retarder provided with the thermistor 5 and its control circuit is, for example, 4 to 5 m, and the thermistor 5 is disconnected or disconnected. However, the temperature protection circuit does not work properly, and the retarder may be overheated and damaged.

SUMMARY OF THE INVENTION The present invention has been made in view of the above points, and detects a disconnection of a thermistor, which is the most important component in the temperature protection of a retarder, and at a low temperature based on the temperature characteristic of the thermistor. An object of the present invention is to provide a temperature detection method of an electromagnetic retarder that can determine whether the thermistor is broken or not and reliably protect the temperature of the retarder.

[0011]

In order to achieve the above object, a temperature detecting method for an electromagnetic retarder according to the present invention comprises a heat-sensitive element for detecting the temperature of the retarder, and a method for detecting the temperature of the retarder based on the temperature detected by the heat-sensitive element. A control circuit for controlling an exciting current flowing through the exciting coil, a magnetic pole core having a plurality of magnetic poles in which N and S poles are alternately magnetized by the exciting current, and an eddy current cylinder provided to face the magnetic pole preparative rotated relative, to generate an eddy current in the vortex cylinder the electromagnetic retarder configurations obtaining a braking force, output voltage of the thermosensitive element
Based on the pressure, when the thermal element is disconnected or
When the temperature is equal to or lower than the predetermined temperature,
Different signal than when the temperature exceeds a predetermined temperature
A distinction circuit for outputting, the retarder actuation signal generated by the introduction of the retarder switch, thus heat sensitive element of the temperature rise of the object to be measured after the retarder actuation predetermined above
A delay circuit for delaying a predetermined time sufficient to reach the temperature, and AND logic between the retarder operation signal delayed by the delay circuit and the output signal of the distinction circuit ,
When the delayed retarder operation signal is input from the delay circuit,
Judgment of the output signal of the mode input from the distinction circuit
In the configuration, a determination circuit for determining whether the abnormal state of the thermal element is true or false is provided, and the temperature of the retarder is detected under the normal state of the thermal element.

[0012]

The temperature is substantially detected after the elapse of a predetermined time from the start of the operation of the retarder, so that the authenticity of the disconnection of the thermal element is determined, and the temperature of the retarder is protected.

[0013]

FIG. 1 shows an embodiment of the present invention.
In the figure, 2 is an exciting coil, 5 and 40 are thermistors, 15 is a magnetic pole, 21 is a retarder switch, 51 to 54 are comparators, 55 is a delay circuit, 56 is a judgment circuit, 57 is a control circuit, 58 is an excitation circuit, 59 is an OR circuit, 60 is an AND circuit, 61 is a light emitting diode, 62,
Reference numeral 63 denotes a resistor.

The thermistor 5 is embedded in the exciting coil 2 and detects a rise in the temperature of the exciting coil 2. The thermistor 40 is provided in at least one pole of the magnetic pole 15 around which the exciting coil 2 is wound, and in a small hole at a position facing the vortex cylinder 16 as shown in FIGS. It is designed to detect. FIG. 1 shows the thermistor 40 installed on the wound magnetic pole 15 of the exciting coil 2 in which the thermistor 5 is embedded. However, the other exciting coil 2 is wound. May be installed on the magnetic pole 15.

A comparator 51 is provided for detecting a temperature rise, which cuts off an exciting current flowing from the exciting circuit 58 to the exciting coil 2 when the temperature rise of the exciting coil 2 detected by the thermistor 5 exceeds a preset temperature. The comparator 52 is a disconnection detection comparator that detects disconnection of the thermistor 5.

A comparator 53 is provided for detecting a rise in temperature that cuts off an exciting current flowing from the exciting circuit 58 to the exciting coil 2 when the temperature rise of the vortex cylinder 16 detected by the thermistor 40 becomes equal to or higher than a preset temperature. The comparator 54 is a comparator.
This is a disconnection detection comparator that detects a disconnection of 0.

The delay circuit 55 delays a retarder operation signal generated when the retarder switch 21 is turned on for a predetermined time. As will be described in detail later with reference to FIG. 3, the determination circuit 56 determines whether the temperature detected by the thermistors 5 and 40 is genuine at low temperatures or based on the disconnection thereof.

The control circuit 57 receives a retarder operation signal based on the turning on of the retarder switch 21, and controls the exciting current to the exciting coil 2 via the exciting circuit 58. When it is determined that the temperature of the thermistors 5 and 40 is broken or the disconnection of the thermistors 5 and 40 from the determination circuit 56 is performed, the exciting current cutoff control for the exciting coil 2 is performed.

The exciting circuit 58 supplies an exciting current to the exciting coil 2 under the control of the control circuit 57. The light emitting diode 61 indicates that the thermistors 5 and 40 are disconnected.

Before describing the operation of FIG. 1, FIG. 3 will be described. FIG. 3 shows an extracted portion of the excitation coil temperature detection of FIG. 1, and the reference numerals in FIG. 3 correspond to those in FIG.

The temperature characteristic of the thermistor 5 is, for example, -30.
12MΩ at 100 ° C, 23KΩ at 100 ° C, 0.2Ω at 300 ° C
At low temperatures of -30 ° C to 0 ° C.
Indicates the order value of

On the other hand, the operating environment of the retarder is -10.degree.
The temperature of the thermistor 5 at about -10 ° C. is about 3 MΩ.
Is about 20 mV.

When the thermistor 5 is disconnected due to vibration or other causes, the voltage input to the comparator 52 by the resistor 63 is zero volt. Therefore, the presence or absence of the disconnection of the thermistor 5 is detected from the usage environment of the retarder. It is found that the comparison reference level of the comparator 52 must be set to 20 mV or less, and that comparator accuracy and noise countermeasures are necessary. In other words, when the ambient temperature of the retarder is low, it is unknown whether the thermistor 5 detects the temperature, that is, the temperature of the exciting coil 2 or whether the wire is disconnected, and it is difficult to reliably detect the temperature. .

To solve this problem, a delay circuit 55 is provided. By providing the delay circuit 55, a retarder operation signal generated by turning on the retarder switch 21 is delayed for a predetermined time and then the retarder operation is performed. A signal (H level) is input to the AND circuit 60 to determine whether the thermistor 5 is disconnected.

That is, after the elapse of the delay time when the retarder operation signal delayed by the delay circuit 55 is input to the AND circuit 60, the temperature of the exciting coil 2 rises due to Joule heat generated in the exciting coil 2. The temperature detected by the thermistor 5 is a temperature of −10 ° C. or more, and the temperature detection voltage is a voltage of 20 mV or more that can sufficiently determine whether the disconnection is detected. That is, the resistor 63,
A distinction circuit composed of the oscillator 52 and its reference voltage source
When the retarder operation signal delayed by the delay circuit 55 for a predetermined time is input to the AND circuit 60, the output level of the comparator 52 differs depending on whether or not the thermistor 5 is disconnected. The authenticity of the disconnection of No. 5 is reliably determined. This will be described in more detail as follows.

FIG. 4 shows a time chart of an embodiment when the thermistor is normal. As described above, the retarder operation signal generated by turning on the retarder switch 21 is delayed by the delay circuit 55 for a predetermined time, and the AND circuit 6
Enter 0. At this timing, the temperature of the thermistor 5 has risen due to Joule heat of the exciting coil 2 or the like, and the voltage of the resistor 63, that is, the temperature detection voltage input to the non-inverting input terminal of the comparator 52 exceeds the comparison reference level K. The L level is input from the comparator 52 to the AND circuit 60.

Therefore, the AND circuit 60 does not output the H level indicating the disconnection of the thermistor 5 described below, and still maintains the L level. FIG. 5 shows a time chart of one embodiment when the thermistor is disconnected.

When the thermistor 5 is disconnected, at the timing when the retarder operation signal delayed by the delay circuit 55 is input to the AND circuit 60, even if the thermistor 5 is heated by Joule heat of the exciting coil 2 or the like, the resistance is not changed. 6
The voltage of No. 3 is at zero level irrespective of low temperature or normal temperature, the output of the comparator 52 is maintained at H level, and the output of the AND circuit 60 is inverted to H level.

As a result, the light emitting diode 61 lights up,
The control circuit 57 controls the cutoff of the exciting current to protect the retarder from heat. In this way, it is possible to reliably determine whether the thermistor is disconnected at a low temperature based on the temperature characteristics of the thermistor.

The comparator 51 is, as described above,
This is a comparator for detecting a temperature rise. The thermistor 5 for detecting the temperature rise of the exciting coil 2 has been described.
The above description is also applied to the thermistor 40 that detects the temperature rise of the vortex cylinder 16.

Next, the operation of FIG. 1 will be described. As described above, if one or both of the thermistor 5 embedded in the exciting coil 2 and the thermistor 40 installed in the magnetic pole 15 are broken, The corresponding comparators 52 and 54 output the H level indicating the disconnection, respectively.

Therefore, if at least one of the thermistors 5 or 40 is disconnected, the OR circuit 5 in the decision circuit 56
9 is at the H level, and when the retarder switch 21 is turned on and the retarder operation signal delayed by a predetermined time by the delay circuit 55 is input to the AND circuit 60, the AND circuit 6
The output of 0 is inverted to H level. That is, the light emitting diode 61 is turned on, and the control circuit 57 controls the cutoff of the exciting current.

FIG. 6 shows an embodiment of a control circuit mainly used in the present invention when the temperature rise of the exciting coil is detected. In the figure, reference numerals 2 to 9 correspond to those in FIG. 10, 21 is a retarder switch, 22 is an abnormal level detector, 23 is a reference level variable circuit, and 24 to 2
6 is a deviation amplifier, 27 to 29 are comparators, 30
To 32 are variable resistors, 33 is a reference level designating unit, 34
Reference numerals 36 to 36 denote transistors, and 37 denotes an OR circuit.

The AND circuit 60 for sending an input signal to one of the four input terminals of the control circuit 57 and the AND circuit 9 shown in FIG. Further, the abnormal level detector 22 may be considered as the comparator 51 in FIG.

When the retarder switch 21 is turned on, all the transistors 34 to 36 in the reference level variable circuit 23 are controlled to be turned off by the designation of the reference level designation section 33. Reference level input to terminal (dead time control voltage)
Is the ground level indicated by the dashed line C in FIG. Accordingly, the output of the comparator 8 becomes a PWM signal having a duty ratio of 100% as shown in FIG. 8 and turns on the switching element 3 via the AND circuit 9.

As a result, an exciting current flows through the exciting coil 2, and the magnetic pole facing surface 1 of the rotating vortex cylinder 16 rotates as described above.
An eddy current is generated in 6-1 and a braking torque is generated in a direction opposite to the rotation direction of the eddy current cylinder 16, and a braking action is performed. At this time, the exciting coil 2 is heated by Joule heat, and the eddy current cylinder 16 is heated by the occurrence of eddy current loss.
The exciting coil 2 is heated through the gap.

FIG. 7 is an operation explanatory diagram of one embodiment of each circuit section of FIG. Now, for example, if the temperature of the exciting coil 2 is 10
When the temperature is 0 ° C or lower, it is called normal, when it is 100 ° C to 120 ° C, it is called a small error, when it is 120 ° C to 140 ° C, it is called a medium error, and when it is 140 ° C or more, it is called a large error. The variable resistors 30, 31, and 32 are 100 ° C, 12
It is set to 0 ° C and 140 ° C, respectively.

7, the detection temperature of the excitation coil 2 from the thermistor 5 is 115 ° C., which corresponds to a small abnormality, and the comparator 27, 28, 29 The outputs are L, H,
H level, and the combination of the levels causes the reference level designation unit 33 to specify the contents of the transistors 34 and 3
5 and 36 are turned off, on, and off, respectively. Since the transistors 34, 35, and 36 of the reference level variable circuit 23 are controlled in this manner, the reference level input to the inverting input terminal of the comparator 8 is the level B indicated by the one-dot chain line B shown in FIG. Accordingly, the output of the comparator 8 becomes a PWM signal having a duty ratio of 60% as shown in FIG. 8, and the switching element 3 is turned on / off by the PWM signal having the duty ratio of 60% via the AND circuit 9. As a result, the exciting current flowing through the exciting coil 2 decreases, and the braking force of the retarder is reduced.
The Joule heat generated in the exciting coil 2 is weakened, and its temperature drops. That is, a state of waiting for recovery to the normal state is set.

For some reason, for example, the vortex cylinder 16
The temperature detected by the thermistor 5 becomes 140 due to sudden heating from
In the case of detecting a large abnormality at a temperature exceeding ℃ or more, the comparators 27, 28, 29 in the abnormality level detection unit 22 are set to L,
L and L levels are output. In this combination, a signal for closing the gate of the AND circuit 9 is output from the OR circuit 37, and the switching element 3 is completely turned off to avoid the large abnormality.

At this time, the reference level designating section 33 particularly includes the transistors 34, 35, 3 as indicated by the horizontal lines.
Although the operation instruction of No. 6 is not issued, the instruction content for turning on the transistor 34 may be used. When the transistor 34 is turned on, the reference level input to the inverting input terminal of the comparator 8 becomes a high level Vcc, and the comparator 8 outputs a PWM signal having a duty ratio of 0%. This is because the level becomes L level.

As described above, the type of the abnormal level during the operation of the brake is detected by the abnormal level detector 22, and the reference level of the comparator 8 for generating the PWM signal is varied by the reference level variable circuit 23 based on the detected signal. As a result, the switching element 3 is driven by the PWM signal having a duty ratio corresponding to the abnormal level, the braking force is varied without stopping the braking force of the retarder, and discomfort to the human body is avoided. You. Further, the temperature rise of the exciting coil 2 returns to the normal state, and the control can be performed at the limit of the braking force.

As is clear from the above description, the reference level may be generated by using a D / A converter in the portion of the reference level variable circuit 23. Further, the duty ratio of the PWM signal can be more finely varied as the number of detected temperatures set by the abnormal level detector 22 increases.

When the thermistor 5 is disconnected, FIG.
As described above, the H level from the AND circuit 60 is input to the AND circuit 9 after a lapse of a predetermined time from when the retarder switch 21 is turned on, so that the switching element 3 is turned off and the thermal protection of the retarder is achieved. Needless to say.

FIG. 9 shows another embodiment mainly including a control circuit used in the present invention when the temperature rise of both the exciting coil and the magnetic pole is detected. 9 includes a thermistor 40 for detecting a rise in temperature of the vortex cylinder 16 and a set of a deviation amplifier 41, a comparator 42, and a variable resistor 43 for detecting a temperature higher than the temperature at which the vortex cylinder 16 is to be protected. It is newly added to.

The comparators 27 to 29 shown in FIG.
It can be considered that the comparator 42 corresponds to the comparator 51 shown in FIG.

The thermistor 40 is embedded in, for example, a hole formed in the surface of the magnetic pole 15 and detects the temperature of the vortex cylinder 16 by using a means such as detecting radiation heat from the vortex cylinder 16. Alternatively, it is also heated by Joule heat from the exciting coil 2.

When the rising temperature of the vortex cylinder 16 detected by the thermistor 40 becomes equal to or higher than the protection temperature set in advance by the variable resistor 43, the L level is output from the comparator 42 (the protection temperature concerned). H level output in the following cases). When the reference level designating unit 33 receives the L level of the comparator 42, the combination is made so that the transistor 34 is preferentially turned on, and a high level Vcc is input to the inverting input terminal of the comparator 8. You. Therefore, the comparator 8
Outputs a PWM signal having a duty ratio of 0%. That is, an L level signal for turning off the switching element 3 is output from the dead time circuit 4. This allows the vortex cylinder 1
6, the temperature of the exciting coil 2 is prevented from rising due to radiant heat from the vortex cylinder 16.

The temperature rise of the exciting coil 2 detected by the thermistor 5 operates in exactly the same manner as described with reference to FIG. 6, and the exciting coil 2 is protected. Also, in the detection of the radiant heat from the vortex cylinder 16, the same protection as in FIG. 8 can be performed.

In the case shown in FIG. 9, when one or both of the thermistors 5 and 40 are disconnected, the determination circuit 5
Since the H level from 6 is input to the AND circuit 9, the switching element 3 is turned off, and the thermal protection of the retarder is achieved.

The control circuit 57 shown in FIGS. 6 and 9 is an embodiment, and is a simpler circuit, for example, in the configuration of FIG. 1, when the retarder operation signal is received, the exciting coil 58 Excitation current is passed through 2 and comparator 5
Various circuit configurations such as a logic circuit that performs control to cut off the exciting current when receiving an H level from the determination circuit 56 are used.

[0051]

As described above, according to the present invention, since the disconnection of the thermosensitive element is detected after the temperature of the object to be measured has risen, the disconnection can be reliably detected. Also, since the reference level for disconnection detection can be set high, the detection is safe without any special consideration for comparator accuracy and noise.
It can be done reliably.

Since the exciting current is supplied to the exciting coil until a predetermined time elapses after the retarder switch is turned on, the temperature detecting method detects the disconnection of the thermosensitive element. The control circuit can be operated irrespective of the temperature characteristics of the thermal element, and the situation where the retarder does not operate at a low temperature does not occur.

When the thermistor is disconnected during operation of the retarder, the disconnection can be recognized by turning on the light emitting diode.

[Brief description of the drawings]

FIG. 1 shows the configuration of an embodiment of the present invention.

FIG. 2 is an exploded perspective view of an embodiment of an exciting coil type retarder.

FIG. 3 is an extraction diagram of an exciting coil temperature detection portion of FIG. 1;

FIG. 4 is a time chart of the embodiment when the thermistor is normal.

FIG. 5 is a time chart of the embodiment when the thermistor is disconnected.

FIG. 6 shows a configuration of an embodiment mainly including a control circuit used in the present invention when detecting a temperature rise of an exciting coil.

FIG. 7 is an operation explanatory diagram of one embodiment of each circuit section of FIG. 6;

FIG. 8 is an explanatory diagram of input and output waveforms of a PWM signal generation comparator.

FIG. 9 shows another embodiment mainly including a control circuit used in the present invention when the temperature rise of both the exciting coil and the magnetic pole is detected.

FIG. 10 is a circuit configuration diagram of a conventional exciting coil type retarder.

FIG. 11 is an explanatory diagram of input / output waveforms of a conventional PWM signal generation comparator.

[Explanation of symbols]

 2 Excitation coil 5, 40 Thermistor 15 Magnetic pole 16 Eddy current cylinder 21 Retarder switch 51, 52, 53, 54 Comparator 55 Delay circuit 56 Judgment circuit 57 Control circuit 61 Light emitting diode

Continuation of front page (56) References JP-A-62-2898 (JP, A) JP-A-58-75465 (JP, A) JP-A-64-102237 (JP, A) JP-A-3-217766 (JP) , A) JP-A-58-75663 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) H02P 15/00

Claims (1)

(57) [Claims] 1. A thermo-sensitive element for detecting a temperature of a retarder,
A control circuit for controlling an exciting current flowing through an exciting coil of the retarder based on a temperature detected by the thermosensitive element; and a magnetic pole core having a plurality of magnetic poles whose N and S poles are alternately magnetized by the exciting current. In an electromagnetic retarder having a structure in which an eddy current cylinder provided opposite to the magnetic pole is relatively rotated to generate a braking force by generating an eddy current in the eddy current cylinder, a thermosensitive element based on the output voltage of the thermosensitive element is used. The element is disconnected
When the temperature of the thermo-sensitive element is lower than the predetermined temperature.
When the temperature of the thermal element exceeds the predetermined temperature
A distinction circuit for outputting different signals between when the retarder actuation signal generated by the introduction of the retarder switch, depending on the temperature rise of the object to be measured after the retarder actuation
A delay circuit for the heat sensitive element by a predetermined time delay predetermined sufficient to reach the predetermined temperature of the retarder actuation signal and the distinguish delayed by the delay circuit
Taking the AND logic of the output signal of the circuit, from the delay circuit
When a delayed retarder operation signal is input, the
A determination circuit configured to determine an output signal in a mode in which the thermal element is being applied;
A temperature detection method for an electromagnetic retarder, wherein the temperature of the retarder is detected under a normal state of the thermal element.