JPH0467763A - Linear dc motor - Google Patents

Abstract

PURPOSE:To prevent it from incurring the burning of a coil, and others by providing a control circuit, which orders the stoppage of a needle according to the temperature detected by a temperature detection means, and inputting the output signal of this control circuit into a motor driving circuit in parallel with the start/stop signal from CPU. CONSTITUTION:The signal detected by a temperature detection element 11 is input into a comparator 18 being a control circuit, and when it becomes the detection voltage over the reference voltage of a reference voltage generator 17, it becomes as H level of signal, and is detected as an abnormal temperature. For the output of CPU 16, it outputs an L level of signal at start and an H level of signal at stoppage. Accordingly, when CPU 16 itself is outputting a stop signal (H level) or the output of a comparator 18 gets on the H level and is an abnormal temperature signal, the output of an OR gate 20 gets on the H level, and an effective stop signal is output to a three-phase motor driving IC 14, and the operation of a rotor, that is, the motor is stopped. Hereby, the burning of a coil 9 can surely be prevented.

Description

[Detailed description of the invention] Industrial applications The present invention relates to a linear DC motor.

2. Description of the Related Art In general, a linear DC motor is used as a drive source for linearly moving an optical head, an image scanner, or the like. As an example, there is a DC brushless linear motor disclosed in Japanese Utility Model Application Publication No. 59-95789. This is a DC brushless linear motor in which the permanent magnet field side is the mover and the coil side is the stator, and is designed to prevent problems such as coil burnout if the coil temperature rises abnormally. It is. For this reason, a temperature sensing element provided with electrodes is attached so as to be in contact with all the coils so that the resistances of the portions corresponding to each coil of the stator are connected in parallel. This makes it possible to accurately and quickly detect the coil with the highest temperature rise among a large number of coils.
Coil burnout, step-out, etc. can be prevented.

Problems to be Solved by the Invention According to the conventional method, the user is only notified of an abnormality caused by a rise in the temperature of the coil using a buzzer, etc., and the temperature of the coil increases even while the user is processing it, causing the coil to become damaged. may cause burnout.

Means for Solving the Problem A field magnet having magnetic poles of N and S poles alternately in the longitudinal direction, and an armature having one or more driving armature coil groups facing the field magnet are provided. In the linear DC motor, one of the field magnet and the armature is used as a mover and the other is used as a stator, and a motor drive circuit for the mover is driven based on a start/stop signal from a CPU. A temperature detection means for detecting the temperature of the drive armature coil group is provided, a control circuit is provided for ordering the movable element to stop according to the temperature detected by the temperature detection means, and an output signal of this control circuit is sent to the CP.
The start/stop signal from U was input to the motor drive circuit in parallel.

Furthermore, holding means for holding the abnormal temperature signal detected by the temperature detecting means is provided on the output side of the control circuit.

The working coil temperature is constantly detected by temperature detection means,
If the detected temperature rises to an abnormal temperature, a stop signal from the control circuit is input in parallel with the start/stop signal from the CPU, and the movement of the mover automatically stops in the same way as when stopping by a CPU command. be done. Therefore, the coil will not be burnt out or the like.

In this case, when the coil temperature rises to an abnormal temperature, the holding means provided on the control circuit output side holds the abnormal temperature signal even if the temperature returns to normal after the stop operation.
The operation of the movable element can also be maintained in a stopped state, and the user will not be able to continue using it without noticing it and cause burnout of the coil.

Embodiment An embodiment of the invention set forth in claim 1 will be described with reference to FIGS. 1 to 4. First, an outline of a moving coil type linear DC motor to which this embodiment is applied will be explained with reference to FIGS. 2 to 4. This DC motor has a stator (stator) 1
and a movable element (rotor) 2 movably disposed opposite to the stator l. The stator 1 is constituted by a field magnet in which N-pole and S-pole magnetic poles 5 are arranged alternately in the longitudinal direction on a stator yoke 4 fixed on a rail-shaped fixed base 3. The rotor 2 has a coil board 8 attached to the lower surface of the rotor yoke 7 which is movably supported by rollers 6 on the rails on both sides of the fixed base 3. The armature is constructed by an armature in which three armature coils 9 are mounted facing the stator 1. A Hall element 10 is provided at the center of each group of armature coils 9 to detect the position by detecting the magnetic field generated from the opposing magnetic poles 5.

Further, a temperature detection element 11 such as a thermistor serving as a temperature detection means is attached to the lower surface of the rotor 2 in contact with each coil 9.

Here, a constant gap is always maintained between the magnetic pole 5 and the coil 9. In addition, a coil 5, a Hall element 10
The output signal line of the temperature sensing element 11 is connected to an external control circuit I3 shown in FIG. 1 via a connector 12 attached to the end of the coil board 8.

This external control circuit 13 first includes three Hall elements 10.
The signals are input to a general three-phase motor drive IC 14, and according to these input signals, drive control signals are output to the motor drive circuit 15 to drive the three-phase coils 9. Here, a start/stop signal from the CPU 16 for controlling the entire motor is also input to the three-phase motor drive IC 14, and start/stop is controlled.

On the other hand, a detection signal corresponding to the coil temperature monitored by the temperature detection element 11 is inputted together with a reference voltage (corresponding to the allowable upper limit temperature of the coil temperature) from the reference voltage generator 17 to a comparator 18 serving as a control circuit. It is configured such that when the detection voltage exceeds the reference voltage, an H level signal is generated and an abnormal temperature is detected. This comparator 18
The output (=abnormal temperature signal) of
It is input to the phase motor drive IC 14.

Therefore, under normal conditions when the coil temperature is not rising, the output of the comparator 18 is at L level. When the coil temperature rises and the detection signal of the temperature detection element 11 exceeds the reference value, the output of the comparator 18 becomes H level, the alarm generator 19 is driven and sounds, and an abnormality due to the rise in the temperature of the coil 9 occurs. is notified to the user.

Here, the output of the CPU 16 is set to output an L level signal at the time of start and to output an H level signal at the time of stop. Therefore, due to the action of the OR gate 20 that receives the abnormal temperature signal, the OR gate 20 outputs the 3-phase motor drive IC 14 only when the CPU 16 outputs the start signal and the output of the comparator 18 is at the L level indicating the normal temperature.
It outputs a start signal that is valid at all times, and outputs a stop signal at other times. That is, when the CPU 16 itself is outputting a stop signal (H level), or when the output of the comparator 18 is H level and an abnormal temperature signal, the OR gate 20 output becomes H level, and 3 A valid stop signal is output to the phase motor drive IC 14, and the operation of the rotor 2, that is, the motor is stopped. As a result, when the temperature of the coil 9 rises and there is a risk of burnout of the coil 9, the alarm generator 19 sounds to notify the user of the temperature rise abnormality, and at the same time, a stop signal is automatically given. coil 9.
Burnout can be reliably prevented. It goes without saying that if there is no temperature abnormality, the control is carried out as usual by the start/stop signal from the CPU 16.

Next, an embodiment of the invention according to claim 2 will be described with reference to FIGS. 5 and 6. The same parts as those shown in the previous embodiment are indicated using the same reference numerals. Simply, a signal holding circuit 21 serving as a holding means is added to the comparator 18 output. This signal holding circuit 21 is for holding the abnormal temperature signal output from the comparator 18, and is configured as shown in FIG. 6, for example. First, the output of the comparator 18 is divided into two, and one side is inputted to the clock terminal of the D-type flip-flop 23 via the inverter 22, and the other side is ORed together with the output Q of this D-type flip-flop 23.
It is input to gate 24.

Here, the input terminal of the D-type flip-flop 23 is always connected to the H level (+5V), and the preset P and clear C terminals are connected to the CPtJ16.

In such a configuration, as an initialization operation immediately after the power is turned on, the preset terminal P of the D-type flip-flop 23 is
Send an H level signal to CPU1 and an L level signal to clear terminal C.
6 pieces are given. As a result, the output of the D-type flip-flop 23. becomes L level. After that, clear terminal C
The initialization is completed by giving an H level signal to . The subsequent output Q of the D-type flip-flop 23 is determined by the clock input and the D input.

Here, at normal temperature, the output of the comparator 18 is at the L level, and the output Q of the D-type flip-flop 23 is also set at the L level due to the above-mentioned initialization, so the output of the OR gate 24 is also at the L level. , the output of the signal holding circuit 21 indicates a normal temperature state.

On the other hand, assume that the coil temperature rises and becomes abnormal.

Then, the output of the comparator 18 becomes H level. At this time, D
Since the output Q of the type flip-flop 23 remains at the L level, the output of the OR gate 24 remains at the H level.
That is, it becomes an abnormal temperature signal and is used to stop the rotor 2, etc. Then, the coil temperature drops and returns to normal temperature again. Therefore, the comparator 18 outputs an L level signal indicating the normal temperature state to the OR gate 24.

At this time, if the rotor 2 continues to move as it is, the rotor 2 will start moving again as it normally would, so the user may not notice that the coil temperature has risen to an abnormal temperature and may continue to use it, resulting in coil burnout or the like. In this regard, when the output of the comparator 18 changes to the L level, the D-type flip-flop 23 detects the rising edge of the clock due to the action of the inverter 22, and the output Q changes to the H level in accordance with the input. That is, since the output Q of the D-type flip-flop 23 continues to output an H level signal indicating an abnormal temperature state, the rotor 2 continues to stop even if the comparator 18 output itself returns to the L level, and the alarm generating device 19 It will continue to ring.

This state continues until reinitialized.

Therefore, the user will not miss the situation where the coil temperature becomes abnormal.

In these embodiments, a movable coil type is used in which the armature is a movable element, but a movable magnet type in which the field magnet side is a movable element may be similarly applied.

Effects of the Invention As described above, the present invention constantly detects the coil temperature by the temperature detection means, and when the detected temperature rises to an abnormal temperature, the motor is activated in parallel with the start/stop signal from the CPU. A stop signal from a control circuit input to the drive circuit can automatically stop the operation of the movable element in the same way as when stopping by a CPU command, and troubles such as coil burnout can be prevented, and in particular, according to claim 2. According to the invention, when the coil temperature rises to an abnormal temperature, the holding means provided on the control circuit output side holds the abnormal temperature signal even if the temperature returns to normal after the stop operation. The operation of the coil can also be maintained in a stopped state, and it is possible to prevent the user from continuing to use the coil without noticing it and causing burnout of the coil.

1 is a block diagram, FIG. 2 is a plan view of the motor, FIG. 3 is a side view thereof, and FIG. 4 is a front view.
5 and 6 show an embodiment of the invention as claimed in claim 2, with FIG. 5 being a block diagram and FIG. 6 being a partial block diagram thereof.

l... Stator, 2... Mover, 5... Magnetic pole, 9...
... Armature coil group, 11... Temperature detection element, 15.
...Motor drive circuit, 16...CPU, 18...Control circuit, 21...Holding means

[Brief explanation of the drawing]

Figures 1 to 4 are collections of the invention claimed in claim 1. figure 33 Seal map

Claims (1)

[Claims] 1. A field magnet having north and south magnetic poles alternately in the longitudinal direction, and an armature having one or more driving armature coil groups facing the field magnet. A linear DC motor is provided, in which one of the field magnet and the armature is used as a mover and the other is used as a stator, and a motor drive circuit for the mover is driven based on a start/stop signal from a CPU, A temperature detection means for detecting the temperature of the drive armature coil group is provided, a control circuit is provided for ordering the movable element to stop according to the temperature detected by the temperature detection means, and an output signal of this control circuit is sent from the CPU. A linear DC motor, characterized in that the start/stop signal is input to the motor drive circuit in parallel with the start/stop signal. 2. The linear DC motor according to claim 1, further comprising holding means for holding the abnormal temperature signal detected by the temperature detecting means on the output side of the control circuit.