JPH0448153Y2 - - Google Patents

Description

[Detailed description of the invention] [Industrial field of application and overview of the invention] This invention relates to a drive detection device for an electric motor, and is used in forced exhaust fans of water heaters, bathtubs, etc., and forced circulation baths. It can be used as a detection device to detect whether a circulation pump or the like inserted into the water circuit of a pot is being driven normally.

The outline of this invention is that if the electric motor used in the exhaust fan or circulation pump described above is operating smoothly, this is detected electrically and the power is turned off or a safety device is activated. To improve the durability of this type of device, which had insufficient durability because the driving state of the electric motor was detected by a mechanical device having a moving part. It is.

[Prior art and its problems] As an instrument incorporating this kind of device, for example, the third
There is a bathtub with a forced exhaust water heater as shown in the figure.

The exhaust gas from the bath heat exchanger 1 and the hot water supply heat exchanger 2 is discharged through a common exhaust passage 3, and an exhaust fan driven by a motor M is installed in the exhaust passage 3. 4 are provided. or,
A wind pressure switch 5 having a built-in diaphragm 52 and the like is provided at the other end of the communication pipe 50, one end of which is open to the exhaust passage 3.

In this device, when the burners 10 and 20 of the bath heat exchanger 1 and the hot water supply heat exchanger 2 burn, the exhaust fan 4 is also driven, and the exhaust gas is discharged from the heat exchangers 1 and 2. is sucked in by the exhaust fan 4 and discharged from the exhaust passage 3.

When the exhaust fan 4 rotates and an exhaust flow is generated in the exhaust passage 3, the air pressure change in the exhaust passage 3 caused by this is detected and the wind pressure switch 5 is activated. If not, it is determined that motor M is malfunctioning, and gas burner 1 is
0,20 combustion is forcibly stopped. That is, the wind pressure switch 5 functions as a detection device that detects whether the exhaust fan 4 is operating normally.

However, the conventional detection device described above has a problem of insufficient durability.

This is due to the diaphragm 5 in the above conventional one.
This is because the driving state of the exhaust fan 4 is detected by a mechanical means incorporating movable parts such as No. 2 and the like.

That is, in the case of the conventional device described above, the detection device includes movable parts such as the diaphragm 52,
However, the movable parts tend to become fatigued with long-term use. Therefore, when the detection device is used for a long period of time, the movable parts are likely to malfunction, reducing the durability of the entire detection device.

[Technical Problem] The present invention has been made in view of the above points, and in order to improve the durability of this type of drive detection device, by detecting an excessive current flowing through the motor M when the motor is started, , the technical problem is to enable the driving state of the motor M to be detected.

[Technical means] The technical means of the present invention for solving the above problems will be described with reference to the conceptual diagram shown in Figure 1.
The technical means of the present invention consists of an overcurrent detection means 68 that outputs an output when a current exceeding a certain level flows through the motor M, and outputs a first signal and a second signal that is output after a certain time delay from this signal. A detection timing setting means, a second AND circuit 64 to which the first signal from the detection timing setting means and the inverted output of the overcurrent detection means 68 are applied, a second signal from the detection timing setting means and the overcurrent detection means. A first AND circuit 62 to which an output signal of 68 is applied is provided, and the first and second AND circuits 62, 6 are further provided.
An OR circuit 63 is provided to which the output of 4 is applied.
The output signal was taken out from the OR circuit 63.''
That's true.

[Effect] The above technical means works as follows.

(During normal operation) When the power is turned on, motor M starts to drive, but
At this time of starting, the motor M needs to generate a large starting torque, so an excessive current flows through the motor M.

When an excessive current flows through the motor M, a signal is output from the excessive current detection means 68, and the reversing force is
It is applied to the 2AND circuit 64. In other words, no signal enters the second AND circuit 64.

Therefore, even if the first signal output from the detection timing setting means is applied to one input terminal of the second AND circuit 64 in this state, the first signal is
The 2AND circuit 64 does not output any output.

Furthermore, since the detection timing setting means has not yet outputted the second signal, the first AND circuit 6 outputs an output on the condition that this second signal is applied.
2 also does not output any output.

Therefore, if the motor M starts to drive when the power is turned on, the first and second AND circuits 62 and 64
OR where there are no signals from and these signals are applied
No output will be output from the circuit 63 either. That is,
Even if a safety device (such as a power cutoff circuit) that is activated by the output of the OR circuit 63 is provided, the safety device does not work.

Next, after a certain period of time has elapsed after the power supply was inserted and the motor M started to start, the current flowing through the motor M drops to a steady value if the motor M is operating normally.

Therefore, the output of the overcurrent detection means is applied to the input side of the first AND circuit 62, and the
The 1AND circuit 62 does not output an output even if it receives the second signal from the detection timing setting means.

Therefore, when the motor M operates normally, the first and second AND
The circuits 62 and 64 do not output any output, and the OR circuit 63, which outputs an output when one of these signals is present, does not generate any output. That is, the safety devices etc. that are activated by the output of the OR circuit 63 are maintained in a stopped state.

(About the case where the motor M does not operate due to a disconnection, etc.) If the electric circuit is disconnected or there is a poor connection, and the current flowing to the motor M is small or does not occur when the power is turned on, an excessive No output is output from the current detection means 68. That is, the second AND to which the inverted output of the overcurrent detection means 68 is applied.
A signal is applied to one input terminal of the circuit 64.

Therefore, when the first signal is outputted from the detection timing setting means in this state and applied to the other input terminal of the second AND circuit 64, both signals are applied to the input terminals of the second AND circuit 64. is applied, and the AND condition is established.
That is, the second AND circuit 64 outputs an output, which allows the OR circuit 63 to output an output to activate the safety device or turn off the power switch of the motor M.

(When the motor M does not rotate due to a brake object biting, etc.) Next, a case where the motor M does not rotate due to a brake object biting the motor M, etc. will be described.

If the power switch is turned on under conditions where the brake object is jammed and the motor M cannot rotate, an excessive current continues to flow through the motor M, and the excessive current detection means 6
8 continues to be applied to one input terminal of the first AND circuit 62. Under such conditions, when a second signal is output from the detection timing setting means and applied to the first AND circuit 62, the operating condition of the first AND circuit 62 is satisfied, and thereby, the second signal is applied to the first AND circuit 62. An output will be output from the first AND circuit 62. Then, the output is the OR circuit 63
The output of the OR circuit 63 produced at this time can be used to turn off the power to the motor M or activate the safety device.

[effect] The present invention has the following unique effects.

Since the circular motion of the motor M can be electrically confirmed by detecting an excessive current flowing through the motor M at the time of starting, the durability is improved compared to the conventional detection device described above which has a mechanically operating part.

[Example] Next, an example of the present invention described above will be described in detail with reference to the drawings.

As shown in FIG. 2, a first resistor 90 is inserted in series with the motor M, and a voltage therebetween is applied to the base of a first transistor 91.

A photocoupler 94 and a diode 96 are inserted into the collector circuit of the first transistor 91, and a second resistor 92 is connected to the emitter circuit of the first transistor 91.
The second resistor 92 determines the operating point of the first transistor 91.

The emitter side potential of the photocoupler 94 is
The output is taken out via a smoothing capacitor 97, processed by a processing circuit A, and applied to a power cutoff circuit 68 as a safety device.

The processing circuit A is provided with an oscillation circuit 82 that is supplied with electricity from a power supply circuit 81, and the oscillation output of the oscillation circuit 82 is counted by a counter 84.

The output of the counter 84 is the first AND circuit 6
2 and the first AND circuit 62
The emitter output of the photocoupler 94 described above is applied, and the output of the first AND circuit 62 is applied as an input signal to the OR circuit 63.
3 is applied.

Also, the output of the first digit of the counter 84 is the
It is input to the 2AND circuit 64, and the corresponding
The 2AND circuit 64 includes the photocoupler 9 described above.
4 is applied, and the output of the second AND circuit 64 is applied to the OR circuit 63 together with the output of the first AND circuit 62 described above. In the figure, 88 is a transistor that becomes OFF when the maximum digit of the counter 84 becomes "H".
Under such conditions, the function is to cut off the output of the oscillation circuit 82 from being sent to the counter 84 side.

The output of the OR circuit 63 to which the input is applied to the first and second AND circuits 62 and 64 is input to the base of the second transistor 86, and the first relay 72 is turned on by the second transistor 86.・
The first relay 7 is turned OFF.
The second normally closed output contact 721 is inserted in the upstream circuit of the start switch 74 in series therewith. Further, a second relay 77 is provided downstream of the start switch 74, and the normally open output contact 7 of the second relay 77
71 is connected in parallel with the starting switch 74 to form a self-holding circuit.

In this embodiment, the photocoupler 94 and the first transistor 9 connected thereto are
1. Furthermore, the first and second resistors 90, 92, etc. are configured as the overcurrent detection means 68 described in the section of the technical means described above.
In addition, an oscillation circuit 82 and a counter 8
The four parts correspond to the detection timing setting means described in the technical means section.

Now, when the start switch 74 is turned on, the motor M becomes energized, but if the motor M is disconnected, the first transistor 91 does not turn on, and the photocoupler 94 does not output any output. Therefore, the second AND circuit 64 to which the inverted output of the photocoupler 94 is applied is connected to the counter 84.
When the first signal is output from , it outputs "H", thereby activating the second transistor 86 . That is,
The first relay 72 constituting the power cutoff circuit 66 operates to open its normally closed output contact 721, turning off the power.

Next, if the motor M does not rotate due to a braking object getting stuck in the motor M, excessive current continues to flow through the motor M when the start switch 74 is turned on.

Then, an "H" signal is continuously applied to one input terminal of the first AND circuit 62, and under such conditions, all the output terminals of each digit (excluding the largest digit) of the counter 84 are When the signal becomes "H", the first AND circuit 62 outputs an "H" signal, which turns on the second transistor 86 and cuts off the power supply in the same way as when the wire is disconnected.

In the above embodiment, if the motor M does not operate normally, turn off the power and turn off the motor M.
However, when applying the present invention to gas appliances such as water heaters, the solenoid valve C for burner B should be shut off as shown by the imaginary line in Figure 2. It goes without saying that it is also possible to perform an operation according to the device to which the present invention is applied, such as issuing an alarm.

[Brief explanation of the drawing]

Fig. 1 is a conceptual explanatory diagram of the present invention, Fig. 2 is a circuit explanatory diagram of an embodiment of the present invention, and Fig. 3 is an explanatory diagram of a conventional example. circuit, 6
4...Second AND circuit, 68...Overcurrent detection means.

Claims (1)

[Scope of utility model registration request] Excessive current detection means 68 that outputs an output when a current exceeding a certain level flows through the motor M, a detection timing setting means that outputs a first signal and a second signal that is output after a certain period of time from this signal, and the detection timing. The first signal from the setting means and the excessive current detection means 6
a second AND circuit 64 to which an inverted output of 8 is applied;
The second signal from the detection timing setting means and the output signal of the overcurrent detection means 68 are applied.
1AND circuit 62 is provided, and the outputs of the first and second AND circuits 62 and 64 are also applied.
This is a drive detection device for an electric motor that is provided with an OR circuit 63 and extracts an output signal from the OR circuit 63.