JPH04190658A - Dc motor - Google Patents

Abstract

PURPOSE:To detect the rotational speed of a motor and the direction of the rotation at the same time by providing a pair of brushes for detecting the rotational speed of a commutator and an armature coil and the direction of rotation, in the DC motor. CONSTITUTION:When armatures COM1-C0M3 and armature coils L1-L3 rotate, brushes BA and B for detecting each rotational speed and rotational direction generates the detection voltage according to the rotation of the commutator and the armature coil. That is, during the rotation of the commutator and the armature coil, the brushes BA and B for detection are connected to one brush for current supply through the commutator or connected to both brushes B+ and B- through the commutator and the armature coil. Therefore, the detection voltage, which shows the rotational speed and the rotation phase angle, is gotten from each brush for detection. And phase relation changes according to the direction of rotation, between the detection voltages of respective brushes for detection. Accordingly, by detecting this phase relation, conversely the detection of the rotational direction of the motor becomes possible.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a brush type DC motor, and particularly to a DC motor having a rotation speed and rotation direction detection function.

[Prior Art] An example of a conventional brush type DC motor will be described with reference to FIGS. 8 and 9.

FIG. 8 is a diagram showing an armature circuit of a conventional three-pole brush type DC motor. In this figure, Ll ”L
3 are armature coils forming three-phase delta windings, and COM1-00M3 are commutators.

Further, B+ and B- are a pair of current supply brushes, and one brush B÷ is connected to the positive electrode of the DC power source E.
The other brush B- is connected to the negative electrode of the DC power supply E.

FIG. 9 shows the brush I3+ of the DC motor shown in FIG.

FIG. 3 is a waveform diagram showing the actance voltage generated between B-. When voltage EO of DC power supply E is supplied between brushes B+ and B-, commutators COMI to C0M3 and armature coil L
l-L3 rotates clockwise. As a result of these rotations, a steep positive and negative pulse voltage (referred to as reactance voltage) is generated between the brushes B+ and B- by electromagnetic induction, as shown in the waveform diagram of FIG. 9. This pulse voltage is 3
In a brushless type DC motor, this occurs every 60 degrees, and in terms of time, the higher the motor speed, the shorter the frequency, and the lower the motor speed, the longer the frequency.

When the DC motor shown in FIG. 8 is driven and controlled by a rotation detection type DC motor control circuit, the rotation of the motor can be detected based on the time period of the pulse voltage. In the conventional rotation detection type DC motor control circuit, a high frequency inductor is inserted between one terminal of the motor and the DC power supply in order to facilitate generation of the pulse voltage.

[Problems to be Solved by the Invention] However, when the conventional DC motor is driven and controlled by a general rotation detection type DC motor control circuit,
It was not possible to detect the direction of rotation of the motor. Therefore, conventionally, when it was desired to detect the rotational speed and direction of the motor, a rotary encoder was directly connected to the motor, but this method had the disadvantage that the device mechanism was bulky and the cost was high.

The present invention has been made in view of the above problems, and an object of the present invention is to provide a DC motor that can simultaneously detect the rotational speed and rotational direction of the motor without using a special detection device such as a rotary encoder. do.

[Means for Solving the Problems] In order to achieve the above object, the DC motor of the present invention includes a plurality of commutators, a plurality of armature coils connected to these commutators as appropriate, and a plurality of armature coils connected to the commutators as appropriate. and at least one pair of current supply brushes for supplying current to the armature coil by contacting the armature coil, and generates a detection voltage for detecting the rotation speed and rotation direction of the commutator and the armature coil. The configuration includes at least one pair of rotation speed and rotation direction detection brushes.

[DC voltage is supplied between the pair of current supply brushes,
When the plurality of commutators and the plurality of armature coils appropriately connected to the commutators rotate, each rotation speed and rotation direction detection brush generates a detection voltage according to the rotation of the commutator and the armature coil. That is, while the commutator and armature coils are rotating, each rotation speed and rotation direction detection brush may be connected to one current supply brush through the commutator, or may be connected to both current supply brushes through the commutator and armature coil. Since the brushes are connected to current supply brushes, detection voltages representing the rotational speed and rotational phase angle can be obtained from the respective rotational speed and rotational direction detection brushes. The phase relationship changes depending on the rotational direction between the respective rotational speeds and detection voltages of the rotational direction detection brushes. Therefore, by detecting this phase relationship, it is possible to conversely detect the rotational direction of the DC motor.

[Example] Hereinafter, an example of the present invention will be described with reference to FIGS. 1 to 7.

FIG. 1 is a diagram showing an armature circuit in a three-pole brush type DC motor M according to an embodiment of the present invention. In FIG. 1, Ll-L3 are armature coils forming three-phase delta windings, and COMI-C0M3 are commutators. Further, B+ and B- are a pair of current supply brushes, one brush B+ is connected to the positive electrode of the DC power source E, and the other brush B- is connected to the positive electrode of the DC power source E.
connected to the negative terminal of BA and B are a pair of brushes for detecting rotational speed and rotational direction.

As shown in FIG. 1, one rotational speed and rotational direction detection brush BA is arranged at a position 40 degrees ahead of the current supply brush B+ on the positive electrode side in the rotational direction, and the other rotational speed The rotation direction detection brush BB is arranged at a position delayed by 40 degrees in the rotation direction with respect to the current supply brush B- on the negative electrode side.

FIG. 2 shows the detection voltage VBA output from the rotation speed and rotation direction detection brush BA1BB shown in FIG.

It is a waveform diagram showing VBB. When the voltage EO of the DC power source E is supplied between the brushes B+ and B-, the armature rotates clockwise from the state shown in FIG. In this rotating state,
Detection voltage VBA1VBB output by both brushes BA1BB
2 (A) and (B) as the armature rotation angle θ changes.
) changes as shown in the waveform diagram. That is, one detection voltage VBA has a voltage amplitude -E of 40 degrees with the power supply voltage level EO as a reference every 120 degrees of the armature rotation angle θ.
It is a pulse voltage with O/2. The other detection voltage VB
B is the voltage amplitude EO/ in a width of 40 degrees with respect to the ground level (O volts) for every 120 degrees of the armature rotation angle θ.
It is a pulse voltage having a voltage of 2. And both detection voltage VBA
, The former (VBA)! l(latter(VB
The phase is 20 degrees ahead of B).

FIG. 3 is a diagram showing a case where the polarity of the DC power source E for the motor M is reversed in order to reverse the rotational direction of the armature of the three-phase brush DC motor M shown in FIG. In this case, since the positions of the current supply brushes B+ and B- are interchanged with respect to the case of FIG. 1, the relative positional relationship of the rotation and rotation direction detection brushes 13BA and BBB is also interchanged.

That is, one rotation speed and rotation direction detection brush B
A is arranged at a position 40 degrees behind the current supply brush B- on the negative electrode side in the rotation direction, and the other rotation speed and rotation direction detection brush BB is arranged at a position delayed by 40 degrees in the rotation direction with respect to the current supply brush B+ on the positive electrode side. It is placed 40 degrees ahead of the

FIG. 4 is a waveform diagram showing the detection voltage VBAVBB output from the rotation speed and rotation direction detection brushes BA and BB of FIG. 3. As can be seen by comparing with the waveform diagram in FIG. 2, when the rotational direction of the armature in this motor M is reversed, the waveforms and phases of the detection voltages VBA and VBH are interchanged. That is, as shown in FIG. 4(A), the detection voltage VBA is a pulse voltage with a voltage amplitude EO/2 in a width of 40 degrees with respect to the ground level (0 volts) every 120 degrees of the armature rotation angle θ. becomes. On the other hand, as shown in FIG. 4(B), the detection voltage VBB is
A pulse voltage with a voltage amplitude -EO/2 is generated every 0 degrees with a width of 40 degrees based on the power supply voltage level EO. Then, between the two detection voltages VBA and VBH, the latter (VBB) leads the former (VBA) by 20 degrees in phase.

In addition, in Figures 2 and 4, the armature coil Ll
- Direct current resistance numerator of L3 LI= r It is illustrated assuming that L3 is equal. Moreover, the influence of induced electromotive force accompanying the rotation of the armature is also ignored in the illustration.

Next, an example of a rotation speed and rotation direction detection type DC motor control circuit using the DC motor M shown in FIGS. 1 to 4 will be explained with reference to FIGS. 5 to 7.

FIG. 5 is a circuit diagram showing an example of a rotation speed and rotation direction detection type DC motor control circuit to which a DC motor M according to an embodiment of the present invention is applied. Also, Figures 6 and 7
The figure is an operation waveform diagram of the main part of FIG. 5.

In Fig. 5, the output shaft of DC motor M (not shown)
When Cot is not rotating, transistor Q32, whose emitter is grounded, is off and the voltage comparator Cot
is outputting a high level voltage to its output section. For this reason, each anode is connected to the primary coil XL of the driving relay.
Both diodes D311 and D32 connected to are off. Therefore, the diode D31. No current is supplied from the DC power source E to the primary coil XL of the driving relay connected between D32 and the positive electrode of the DC power source E.

Since no current flows through the primary coil XL, the secondary contact Xs of the drive relay connected between the positive electrode of the DC power supply E and the terminal TI of the DC motor M is turned off.

Since the secondary contact XS is off, the power supply voltage E is applied to the terminal T of the DC motor M connected in series with the secondary contact XS.
O is not supplied. Here, the terminal TI is connected to the brush B+ in FIG. 1, and the grounded terminal T2 is connected to the brush B-. Therefore, the terminal T3 connected to the rotation detection brush BB of the first rRJ is connected to the terminal T2 via the commutator (COMI to C0M3) and the brush B-.
or commutator and armature coil (L
l-L3) and the terminal TI via the brush B+. Furthermore, the terminal T4 connected to the rotation detection brush BA in FIG. L3) and brush B
- is connected to terminal T2 via. That is, one ends of the terminals T3 and T4 of the DC motor M are grounded or open.

The other end of the terminal T3 is connected to a differentiating circuit including a capacitor C31 and a grounded resistor R31 for rotation detection. When the output shaft of DC motor M is not rotating, connection point 3 between capacitor C31 and resistor R31
0 voltage, ie, the reset signal 832 is at O volts. This reset signal S32 is supplied to the base of an NPN type reset transistor Q31 via a resistor R32. Note that the diode D30 connected in parallel with the resistor R31 is a clamping diode.

Transistor Q31, whose emitter is grounded, is off because the reset signal 832 applied to its base is O volts. One end of a time constant circuit 50, which is a parallel circuit of a resistor R33 and a capacitor C32, is connected to the collector of the transistor Q31. Note that the other end of this time constant circuit 50 is connected to the positive electrode of the DC power supply E. Therefore, the output terminal 50a of the time constant circuit 50 connected to the collector of the transistor Q31 outputs the voltage EO of the DC power supply E as the drive control signal S33.

The output terminal 50a of the time constant circuit 50 is a voltage comparator C.
It is connected to the non-inverting input of ot.

Therefore, the voltage EO is supplied to the non-inverting input of the voltage comparator Cot. On the other hand, a variable resistor VR31 for torque control is connected in parallel with the DC power source E, and a sliding contact of this variable resistor VR31 is connected to an inverting input part of a voltage comparator Cot. variable resistance V
The sliding contact R31 supplies a voltage eO obtained by dividing the voltage EO to the inverting input of the voltage comparator CO1.

Therefore, the voltage comparator COI continues to output a high level voltage at its output since the voltage EO supplied to its non-inverting input is greater than the voltage eO supplied to its inverting input. As a result, the diode D31 whose cathode is connected to the output part of the voltage comparator COI is turned off. Also, since the diode D32 whose cathode is connected to the collector of the transistor Q32 is also turned off,
Now that the output shaft of the DC motor M is not rotating, a starting signal 831, which is a high level voltage, is applied to the base of the transistor Q32 via a voltage divider circuit consisting of a resistor R34 and a resistor R35 whose one end is grounded. Suppose that is supplied. Then, transistor Q32 is turned on. By turning on transistor Q32, diode D32 is also turned on. Therefore, current is supplied from the DC power supply E to the primary coil XL of the drive relay. Since current flows through the primary coil XL, the secondary contact XS of the drive relay is turned on.

When the secondary contact XS is turned on, voltage EO is supplied to the DC motor M from the DC power supply E. This causes the output shaft (not shown) of the DC motor M to rotate. That is, the armature (commutator COMI-COM3 and armature coils L1 to L3) of the DC motor M rotates. When the armature rotates, a detection voltage VBB is generated at terminal T3. This detection voltage VBB is a pulse P'l~P as shown in FIG. 6(A).
'n+1. Note that the voltage amplitude of the pulse is EO/2, which is obtained by dividing the voltage EO by two armatures.

The detection voltage VBB generated at terminal T3 is connected to capacitor C3.
1 and a resistor R31.

The differentiated detection voltage VBB becomes a reset signal S32 having pulses as shown in FIG. 6(B). This reset signal S32 is applied to the transistor Q via the resistor R32.
31 bases. Therefore, transistor Q31 is turned on momentarily every time a positive pulse of reset signal S32 is supplied.

By instantaneously turning on this transistor Q31, the voltage level of the output terminal 50a of the time constant circuit 50 (signal S3
3 level) becomes low level, and capacitor C
32 is charged. By this charging, one capacitor C3
The charge stored in the reset transistor Q31
Therefore, the time constant circuit 50 is discharged after turning off.
After the transistor Q31 is turned off, the voltage at the output terminal 50a of the transistor Q31 gradually increases with a time constant determined by the capacitor C32 and the resistor R33.

The voltage output from the output terminal 50a is supplied to the non-inverting input of the voltage comparator Cot as a drive control signal S33. Therefore, as shown in FIG. 6(C), the voltage at the non-inverting input of voltage comparator Cot changes to O volts (
(ground level), and then rises from O volts toward the voltage EO of the DC power supply E, repeating this pattern.

In this way, the drive control signal 833 is reset to O volts each time a positive pulse of the reset signal S32 occurs, so if the output shaft of the DC motor M is rotating at a predetermined speed or higher, the drive control signal 833 333 never exceeds the voltage eO, which is the threshold voltage between high and low levels. In other words, under normal driving conditions, the voltage comparator C
OI outputs a low level voltage at its output because the drive control signal 833 applied to its non-inverting input is less than the voltage eO applied to its inverting input.

As a result, the diode D31 is turned on, so even if the supply of the starting signal 831 is stopped and the transistor Q32 and the diode D32 are turned off, the primary filter X of the driving relay is
The current from the DC power source E continues to be supplied to L. Since the current continues to flow through the primary coil XL, the secondary contact XS remains on, and the voltage EO continues to be supplied to the DC motor M from the DC power supply E. Therefore, the output shaft of the DC motor M continues to rotate.

However, in a state where the supply of the start signal 831 is stopped, the rotation of the output shaft of the DC motor M decreases, and the pulse generation interval of the detection voltage VBB changes from P'n and P' in FIG.
When the distance from n+1 becomes as long as TY, the voltage value of the drive control signal 833 exceeds the voltage eO and becomes a high level. Thereby, the voltage comparator COI outputs a high level voltage at its output since the signal S33 supplied to its non-inverting input is greater than the voltage eO supplied to its inverting input.

As a result, diode D31 is turned off, and diode D3
Since 2 is also off, the primary coil XL of the drive relay
No current flows through the terminal, and the secondary contact XS turns off. 2
Since the next contact XS is off, the terminal T of the DC motor M
I is not supplied with voltage EO. Therefore, it is possible to reliably prevent a locking current from flowing when the DC motor M is locked.

Also, the voltage e is set by variable resistor VR31 for torque control.
By changing O, the longest interval of pulses of the detection voltage VBH that allows the secondary contact xS of the drive relay to remain in the ON state can be arbitrarily set. Therefore, variable resistor VR31
By changing the position of the sliding contact, it is possible to arbitrarily control the rotational speed of the DC motor M immediately before stopping, which makes it possible to control the torque of the DC motor M.

In this way, in this DC motor control circuit, the motor M
A signal representing the rotational speed of the current supply brushes B+ and B-
Since the detection voltage VBB is obtained from the detection brush BB rather than as a motor pulse from the motor pulse, a high frequency inductance for promoting the generation of motor pulses is not required.

Note that similar effects can be obtained by using the detection voltage VBA from the detection brush BA instead of the detection voltage VBH from the detection brush BB.

Next, the motor rotation direction detection function in this DC motor control circuit will be explained with reference to FIGS. 5 and 7.

In FIG. 5, the other ends of terminals T3 and T4 are connected to input terminals of voltage conversion circuits 10 and 12, respectively, for detecting the direction of rotation. These voltage conversion circuits 10.12
is the pulse te detection IE pressure Vn from terminals T3 and T4
A, vBBwoT'T'L level pulse signals SA, S
These are circuits for converting to H, and their output terminals are D
The data terminal and clock terminal C of the flip-flop 14 are respectively connected.

When the output shaft of DC motor M is not rotating, terminal T3
, T4 does not output the detection voltages VBB and VBA, so the pulse signal 5 is output to the output terminal of the voltage conversion circuit 10.12.
A1SB is not generated and therefore flip-flop 1
4 is not working.

When the output shaft of DC motor M rotates, terminal "3) T4
Detection voltages VBB and VBA are output. When the direction of rotation is such that the armature rotates clockwise as shown in FIG. 1, for example, both detection voltages VBA1VBB
C. The waveforms are as shown in the waveform diagrams in FIGS. 2(A) and 2(B). Therefore, at this time, the voltage conversion circuit 10.12
TTL level pulse signal SA obtained at the output terminal of
The SR will be as shown in section KO in Figure 7, and the S
A is 20 degrees ahead of SR in phase. Then, in the flip-flop 14, the clock signal (S
At the rising edge of B), the level of the data signal (SA ”)
By taking in “L”, “L” is output from the output terminal Q.
A level rotation direction detection signal R8 is output.

Assume that the direction of rotation of the output shaft of the DC motor M is reversed and the armature is rotating counterclockwise as shown in FIG.

At this time, both detection voltages VBA and VBB are shown in Figure 4 (A).
, as shown in the waveform diagram of (B). Therefore, the TTL level pulse signal SA%SB obtained at the output terminal of the voltage conversion circuit 10.12 at this time is as shown in the section Kl of FIG. 7, and the phase of SB is 20 degrees ahead of SA. I'm here. Then, the flip-flop 14 receives the "H" level of the data signal (SA) at the rising edge of the clock signal (SB), and outputs the "H" level rotational direction detection signal R8 from its output terminal Q. be done.

In this way, in this DC motor control circuit, the DC motor M
A rotational direction detection signal R8 representing the rotational direction of the output shaft or armature at is obtained at the output terminal of the flip-flop 14.

[Effects of the Invention] The present invention is constructed as described above, and the detection voltage for detecting the rotational speed and rotation direction is obtained from the DC motor itself, so that special equipment such as a rotary encoder is not required. A small and low-cost DC motor can be provided without the need for a rotational speed and rotational direction detection device.

[Brief explanation of drawings]

Fig. 1 is an armature circuit diagram showing one embodiment of the DC motor of the present invention, Fig. 2 is a waveform diagram showing the detected voltage of Fig. 1, and Fig. 3 is a waveform diagram showing the detected voltage of Fig. 1.
The figure is an armature circuit diagram showing an example of reversing the rotation direction in the DC motor in Figure 1, Figure 4 is a waveform diagram showing the detected voltage in Figure 3, and Figure 5 is the same as in Figures 1 and 3. A circuit diagram showing an example of a rotational speed and rotational direction detection stone flow motor control circuit using a DC motor, Fig. 6 is an operation waveform diagram of the main part of Fig. 5, and Fig. 7 explains the rotational direction detection function. Figure 5 is an operating waveform diagram of the main parts for
FIG. 3 is a waveform diagram showing actance voltage. In addition, in the symbols used in the drawings, COMI-C0M3... Commutator L! ~L3
・・・・・・Armature coil B+, B−・・・・・・
...Current supply brush BA1BB...Brush for rotation and rotation direction detection.

Claims (1)

[Claims] It has a plurality of commutators, a plurality of armature coils appropriately connected to these commutators, and at least one pair of current supply brushes that contact the commutators and supply current to the armature coils. The brush-type DC motor is characterized by comprising at least one pair of rotational speed and rotational direction detection brushes that generate detection voltages for detecting the rotational speed and rotational direction of the commutator and armature coils. DC motor.