JPH09145412A - Step motor type measuring instrument - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a step motor type measuring instrument which can reliably hold a painter in an origin position when a power source switch is turned off and whose pointer does not unnecessarily move in an unexcited condition. SOLUTION: A magnet 350 is embedded in an inside lower part of a tip indicating part 410 of a pointer 400 by press-in or an adhesive so that positional dislocation is not caused. A stopper pin 380 composed of a magnet is erected on a dial 200 so that a magnetic action is generated between it and this magnet 350. The pointer 400 can be made unnecessarily immovable in an unexcited condition by the magnetic action.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a step motor type instrument for performing a change in a measured amount, for example, an engine speed of a vehicle, by instructing an angle of a pointer rotating on a dial plate, and more particularly to a pointer holding structure. is there.

[0002]

2. Description of the Related Art As a step motor in a step motor type instrument, for example, as disclosed in Japanese Patent Laid-Open No. 6-38426, a PM (permanent magnet) which can easily obtain a relatively large driving torque and can easily perform forward / reverse rotation control. ) Type stepping motors are often used. This PM type step motor guides the exciting magnetic poles of a coil wound in an annular shape to a facing surface of a rotor made of a permanent magnet by a yoke made of a magnetic material to rotate the rotor. , A plurality of magnetic poles are magnetized at a constant pitch, while a plurality of comb-shaped pole teeth facing the magnetic pole of the rotor in a predetermined space are extended on the yoke, and the magnetic poles are excited by the magnetic poles. The rotor is bidirectionally rotated by a predetermined pitch by a magnetic attraction force or a repulsive force between the pole and the magnetic pole of the rotor.

In such a PM type step motor, a complicated magnetic circuit is formed between the rotor and the yoke including the pole teeth even when there is no signal to the coil in the non-excited state. A weak magnetic force called detent torque acts on the rotor by the magnetic circuit.

[0004]

By the way, in a step motor type instrument using a step motor of this kind as a pointer driving movement, for example, like the crossed coil type instrument, the pointer is set to a character when the power is off (non-excitation). It may require a stopper mechanism that stays in the base position on the plate. However, in the step motor type instrument, since the rotor is affected by the magnetic force in the non-excited state as described above, it is difficult to hold the pointer stably at the base point position by the stopper mechanism, and the pointer rises due to slight vibration etc. Is likely to occur.

The present invention relates to a step motor type instrument, and an object of the present invention is to hold a pointer so as not to move unnecessarily in a non-excited state.

[0006]

In order to solve the above-mentioned problems, the present invention bidirectionally drives a step motor according to an increase or decrease of an input signal according to a measured amount, and directly or decelerates the output shaft of the step motor. In the step motor type instrument in which the pointer fixed through the mechanism rotates on the dial plate located between the step motor and the pointer, and the position of the pointer indicates the measured amount, the power switch is turned off. In some cases, the pointer is held at the base point position of the dial by magnetic action.

Further, according to the present invention, the step motor is bidirectionally driven according to the increase or decrease of the input signal according to the measured amount, and the pointer fixed to the output shaft of the step motor directly or through the speed reducing mechanism is used in the step. In a step motor type instrument that rotates on a dial located between the motor and the pointer and indicates the measured amount by the position of the pointer, when the power switch is turned off, the step motor is turned in the decrease instruction direction. The pointer is zeroed and held at the base point position of the dial by magnetic action while being moved.

Further, according to the present invention, when the ignition switch of the vehicle, which is the power switch, is turned off, the pointer is held at a base point position slightly lower than the starting point of the dial by a magnetic action, and the ignition switch is turned on. At the time, the pointer is moved to the starting point position of the dial.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION As shown in FIG. 8, a zero-reset magnet 350 is buried under the tip of the pointer portion 410 of a pointer 400 so as not to be displaced by press-fitting or an adhesive. A stopper pin 380 made of a magnet is erected on the dial plate 200 so that a magnetic action is generated between them. When the power switch is turned off, the pointer 400 is set at the base position by the magnetic action of the zero-reset magnet 350 and the stopper pin 380. The pointer 40
You can prevent 0 from moving unnecessarily.

As shown in FIGS. 9 and 10, when the ignition switch 900, which is a power switch, is turned off, the pointer 400 is located at a base point position which is slightly minus the zero point, which is the starting point of the dial 200, due to magnetic action. When the ignition switch 900 is turned on while keeping the contact state with the stopper pin 380, the drive circuit 600 supplies an excitation signal to the coil to move the pointer 400 to the starting point position of the dial 200, and after starting the engine. The pointer 400 gives an instruction in response to an input signal from the sensor 700, so that the pointer 400 can be prevented from moving unnecessarily in the non-excited state when the ignition switch 900 is off.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below based on each embodiment shown in the accompanying drawings.

FIG. 1 shows a step motor applicable to the present invention. Two stepped resin bobbins 1A,
A collar portion 2A, 2B is formed in 1B so that a coil (not shown) for supplying an excitation signal is wound, and each of the collar portions 2A, 2B has a terminal holding portion 3A, 3 integrated therewith.
B is formed.

Terminals 4A and 4B to which the ends of the coils are connected are fixed to the terminal holding portions 3A and 3B. These terminals 4A and 4B are insert-molded when molding the bobbins 1A and 1B. The external connection ends 41A and 41B are formed by bending the coil end connection portion outward and projecting the other end upward.

Each bobbin 1A, 1B has yokes 5A, 5B laminated on both sides thereof, and the bent comb-teeth-shaped pole teeth 5 are formed.
C and 5D are made to face the hollow portions 6A and 6B of the bobbins 1A and 1B, and the pole teeth 5C and 5D of the yokes 5A and 5B are arranged out of phase, and the hollow shafts 6A and 6B have output shafts. The rotor 8 made of a permanent magnet fixed to the rotating shaft 7 (shown with the upper end side cut off in the drawing) is
The pole teeth 5C and 5D of A and 5B and their magnetic poles are arranged so as to face each other, that is, the exciting magnetic poles of the coil wound annularly are guided to the facing surface of the rotor 8 by the respective yokes 5A and 5B. In order to rotate the rotor 8, a plurality of magnetic poles are magnetized on the radial circumferential surface of the rotor 8 at a constant pitch, while the yokes 5A and 5B face a plurality of magnetic poles of the rotor 8 with a predetermined space therebetween. The pole teeth 5C and 5D are extended, and the pole teeth 5
The rotor 8 is rotated by a predetermined pitch in the forward and reverse directions by a magnetic attraction force or a repulsive force between the exciting magnetic poles guided to C and 5D and the magnetic pole of the rotor 8.

These component elements are housed and fixed in a case body 9 made of a magnetic material such as metal in a laminated mounting state. The case body 9 has a cup-shaped case 9A made of a magnetic material and a lid for covering the opening. 9B and a flange 9B made of a magnetic material as a bearing.
And the bearing portion 91A is also provided in the center of the bottom of the cup-shaped case body 9A to support the rotation shaft 7.

On the cup-shaped case 9A and the flange 9B of the case body 9, the terminal holding portions 3A and 3B of the bobbins 1A and 1B are provided.
Openings 92A and 92B for externally arranging the components are formed, the assembly of component elements is housed in the cup-shaped case 9A, and the flange 9B is joined by caulking, welding, etc. Complete. Reference numeral 93 is a cut-out piece for crimping and fixing the step motor 100 to the printed board, but it is not particularly necessary for stabilizing the magnetic circuit, and the openings 92A, 92B for leading out the terminals are provided.
It is sufficient to devise so that the shape of the case does not become an irregular shape of the case body 9.

FIG. 2 shows the first embodiment of the present invention, in which the upper end of the flange 9B of the step motor 100 is
A mounting plate 300 made of resin for fixing the dial plate 200 with screws or the like is fixed, the rotary shaft 7 as an output shaft penetrates through the mounting plate 300 and protrudes upward, and the upper end of the rotary shaft 7 is made of resin. The manufactured pointer 400 is fixed by press fitting or the like.

A stopper pin 310 and a magnet press-fitting portion 320 are integrally formed on the upper surface of the mounting plate 300, and the magnet 330 is partly exposed in the magnet press-fitting portion 320 in the direction of the rotation axis 7. It is arranged so as not to be displaced by press fitting or adhesive. The contact member 340 and the magnet 3 are attached to the rotary shaft 7 below the dial 200.
Numeral 50 is fixed so as to interlock with the rotary shaft 7, and a part of the contact member 340 serves as a contact portion 341 projecting in the direction opposite to the horizontal rotary shaft 7 to form a step motor type instrument. There is. The zero of the pointer 400, that is, the pointer 40
In order to hold 0 at the base point position of the dial 200, the step motor 100 is rotated in the decreasing instruction direction when the power switch is turned off, and the zero point of the dial 200 or a minus point slightly less than the zero point called free zero. The stopper pin 310 provided at the base position and the contact portion 341 of the contact member 340 perform zeroing and holding. At this time, the magnetic action of the magnets 330 and 350 causes the stopper pin 310 to move.
So that the contact member 340 and the contact member 340 are not separated from each other.
The positional relationship of 0 is set. Specifically, as shown in FIG. 3, it is possible to selectively use a configuration that uses suction force (FIG. 3A) and a configuration that uses repulsion force (FIG. 3B). With this structure, the pointer 400 is stable and does not move unnecessarily in the non-excited state when the power switch is off.

The contact member 340 and the magnet 350 may be fixed upside down with respect to the positional relationship, but the height dimension of the stopper pin 310 can be made smaller with the configuration shown in FIG. Is advantageous. Note that one of the magnets 330 and 350 may use a magnetic material such as iron instead of the magnet.

FIG. 4 shows a second embodiment of the present invention, in which the contact member 340 and the magnet 350 (see FIG. 2) of the first embodiment.
Of the contact magnet 360 is integrally molded with a resin magnet, and is fixed to the rotary shaft 7. A part of the contact magnet 360 is a contact portion 361 protruding in the direction opposite to the horizontal rotary shaft 7. Has become. The other points are similar to those of the first embodiment, and the details thereof are omitted. According to this structure, the same operation as that of the first embodiment can be obtained, and the number of parts can be reduced as compared with the first embodiment, so that the number of parts can be reduced and the assembling workability can be simplified. can do. The magnet 330 may use a magnetic material such as iron instead of the magnet.

FIG. 5 shows a third embodiment of the present invention. The stopper pin 310 and the magnet press-fitting portion 3 of the second embodiment are shown.
20 (see FIG. 4) is also integrally formed on the upper surface of the mounting plate 300, the holding portion 370 is configured so that a part of the holding portion 370 can contact the contact portion 361 of the contact magnet 360 with a small area. Thus, the abutting portion 371 is cut at an acute angle. In other respects, it is similar to the second embodiment,
The details are omitted. According to this configuration, the same operation as that of the second embodiment can be obtained, and the number of parts can be reduced as compared with the second embodiment, so that the number of parts can be reduced and the assembling workability can be simplified. can do. The magnet 330 may use a magnetic material such as iron instead of the magnet.

FIG. 6 shows a fourth embodiment of the present invention, in which the magnet 3 is provided below the tip of the pointer 400 of the pointer 400.
50 is embedded so as not to be displaced by press-fitting or an adhesive, and a magnet 330 is press-fitted or adhesive by a magnet 330 from the back side of the dial 200 so as to generate a magnetic action with the magnet 350. It is buried so that it will not exist.
Further, the stopper pin 310 is provided upright on the dial plate 200. According to this structure, the same operation as that of each of the above-described embodiments can be obtained, and the magnet press-fitting portion 320, the magnet 330, and the contact member 340 are provided between the dial plate 200 and the mounting plate 300 (see FIG. 2). , Magnet 350 (for the above, refer to the first embodiment of FIG. 2), magnet press-fitting section 320, magnet 330, contact magnet 360.
(These are the second embodiment of FIG. 4), the magnet 330, the contact magnet 360, and the holding section 370 (these are the third embodiment of FIG. 5). The overall height dimension of the step motor type instrument can be reduced as compared with the embodiment. Note that the stopper pin 310
Is formed integrally with the dial plate 200, or is formed integrally with the mounting plate 300 (see FIG. 2).
It is also possible to have a configuration of penetrating. Also, the magnet 33
One of 0 and 350 may use a magnetic material such as iron instead of a magnet.

FIG. 7 shows a fifth embodiment of the present invention, in which a magnet 350 is embedded under the base portion 420 of the pointer 400 so as not to be displaced by press fitting or an adhesive.
A magnet 330 is embedded from the back side of the dial plate 200 so that a magnetic action is generated between the magnet 350 and the magnet 350 by press-fitting or an adhesive so as not to cause displacement. The other points are similar to those of the fourth embodiment, and the details thereof are omitted. With this configuration, the same operation as that of the fourth embodiment can be obtained, and the balance weight normally embedded in the base portion 420 of the pointer 400 can also be used as the balance weight of the pointer 400 by the magnet 350. The number of points can be reduced and the assembling workability can be simplified. Further, one of the magnets 330 and 350 may use a magnetic material such as iron instead of the magnet.

FIG. 8 shows a sixth embodiment of the present invention, in which the magnet 3 is provided below the tip of the pointer 410 of the pointer 400.
50 is embedded by press fitting or an adhesive so as not to be displaced, and a stopper pin 380 made of a magnet is erected on the dial plate 200 so as to generate a magnetic action with the magnet 350. The other points are similar to those of the fourth embodiment, and the details thereof are omitted. According to this structure, the same operation as that of the fourth embodiment can be obtained, and since the stopper pin 380 that also serves as the stopper pin 310 and the magnet 330 (see FIG. 6) of the fourth embodiment is used, the parts are The number of points can be reduced and the assembling workability can be simplified. Note that one of the magnet 350 and the stopper pin 380 may use a magnetic material such as iron instead of the magnet.

FIG. 9 and FIG. 10 are for explaining the operation of each of the above-mentioned embodiments, and show a preferred usage when the present invention is applied, for example, as a tachometer for instructing the engine speed of a vehicle as a measured quantity. ing. Note that, as a representative of the above-described embodiments, FIG. 9 uses the sixth embodiment shown in FIG. Further, in FIG. 10, 500 is a step motor 100.
A drive circuit including an output transistor for supplying an excitation signal to the two-phase coils in the above-mentioned respective embodiments, 6
Reference numeral 00 is a control circuit provided with a phase control circuit for supplying a microstep signal to the coil, an up / down counter, a sine wave ROM, a cosine wave ROM, a microcomputer, or the like, and 700 is a frequency or cycle depending on the engine speed. A sensor that outputs a varying pulsed input signal to the control circuit, and counts the number of pulses from the sensor 700, for example, in the control circuit 600 to obtain the engine speed, and increases / decreases from the engine speed at the next counting. The comparison is performed, and the drive circuit 500 is controlled so as to supply the excitation signal according to the difference to the coil. Reference numeral 800 denotes an on-vehicle battery, and a voltage is supplied to the drive circuit 500 and the control circuit 600 via an ignition switch 900 which is a power switch.

When the ignition switch 900 is off (“LOCK” position in FIG. 10), the pointer 400 is placed at the base point position (point A in FIG. 10) which is slightly minus the zero point of the dial 200 due to magnetic action. Stopper pin 3
When the ignition switch 900 is turned on (“ACC” or “O” in FIG. 10), it is kept in contact with 80 (FIG. 10A).
(N position), the driving circuit 600 supplies an excitation signal to the coil to move the pointer 400 to the starting point position (point B in FIG. 10) which is the zero point of the dial 200 (FIG. 10 (b)). ), Sensor 70 after engine start
The pointer 400 gives an instruction according to an input signal from 0 (FIG. 10 (c)).

According to this structure, the pointer 400 can be prevented from moving unnecessarily in the non-excited state when the ignition switch 900 is off, and when the ignition switch 900 is on, the pointer 400 is a starting point which is a starting point. By moving the pointer 400 to the position, the pointer 400, which was held as if it was fixed to the stopper pin 380, can be prevented from initial movement failure that seems to start moving suddenly, which gives the user a feeling of strangeness. Absent.

The pointer 400 may be directly fixed to the rotary shaft 7 as in the above-described embodiments, or may be fixed to the rotary shaft 7 through a speed reducing mechanism. Further, the zeroing can be performed only by the magnetic action, or by the magnetic action while rotating the step motor 100 in the reduction instruction direction when the power switch is turned off. The starting point corresponds to a zero point for a tachometer or a speedometer, an E point for a fuel gauge, a C point for a thermometer, and the like. Further, it goes without saying that the magnetic action is set so as to be weak so as not to affect the driving of the pointer 400 by the step motor 100.

[0029]

According to the present invention, the step motor is bidirectionally driven according to the increase or decrease of the input signal according to the measured amount, and the pointer fixed to the output shaft of the step motor directly or through the speed reducing mechanism is used in the step. In a step motor type instrument that rotates on a dial located between a motor and the pointer and indicates the measurement amount by the position of the pointer, a base position of the dial due to magnetic action when a power switch is turned off. To hold the pointer, or to turn the step motor in the decrease instruction direction when the power switch is turned off, and to cause the pointer to zero and hold at the base point position of the dial due to the magnetic action. When the switch is turned off, it can be reliably returned to the specified position and the pointer can be prevented from moving unnecessarily in the non-excited state. Even if the cross-sectional and turned, without causing a large error in the instruction, it is possible to perform an accurate indication.

According to the present invention, when the ignition switch of the vehicle, which is the power switch, is turned off, the pointer is held at a base point position which is slightly minus the starting point of the dial by a magnetic action, and when the ignition switch is turned on. By moving the pointer to the starting point position of the dial, it is possible to prevent the pointer from moving unnecessarily in the non-excited state when the ignition switch is off, and when the ignition switch is on, the pointer is at the starting point. By moving the pointer to the starting point position, it is possible to prevent the initial movement failure in which the pointer that is held as if it is fixed seems to start moving suddenly.

[Brief description of the drawings]

FIG. 1 is an exploded perspective view of a step motor applied to the present invention.

FIG. 2 is a perspective view of a main part of the first embodiment of the present invention.

FIG. 3 is an explanatory view of a main part for explaining a zero-reset operation of the embodiment.

FIG. 4 is a perspective view of an essential part of a second embodiment of the present invention.

FIG. 5 is a perspective view of an essential part of a third embodiment of the present invention.

FIG. 6 is a perspective view of an essential part of a fourth embodiment of the present invention.

FIG. 7 is a perspective view of essential parts of a fifth embodiment of the present invention.

FIG. 8 is a perspective view of a main part of a sixth embodiment of the present invention.

FIG. 9 is a plan view of a principal part for explaining the operation of each embodiment of the present invention.

FIG. 10 is a block diagram illustrating a circuit configuration of each embodiment of the present invention.

[Explanation of symbols]

 100 step motor 200 dial plate 300 mounting plate 310 stopper pin 320 magnet press fitting part 340 abutting member 350 magnet 360 abutting magnet 370 holding part 380 stopper pin 400 pointer 900 ignition switch (power switch)

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification number Office reference number FI technical display location H02P 8/00 H02P 8/00 303B

Claims (3)

[Claims] 1. A step motor is bidirectionally driven according to an increase or decrease of an input signal according to a measured amount, and a pointer fixed to the output shaft of the step motor directly or through a speed reduction mechanism is the step motor and the pointer. In a step motor type instrument that rotates on the dial located between and, and indicates the measured amount by the position of the pointer, the pointer is placed at the base point position of the dial by magnetic action when the power switch is off. A step motor type instrument characterized by being held. 2. A step motor is bidirectionally driven according to an increase / decrease in an input signal according to a measured amount, and a pointer fixed to the output shaft of the step motor directly or via a speed reduction mechanism is the step motor and the pointer. In a step motor type instrument that rotates on a dial plate located between and, and indicates the measurement amount by the position of the pointer, while rotating the step motor in a decrease instruction direction when the power switch is off, A step motor type instrument characterized in that the pointer is zeroed and held at the base point position of the dial by magnetic action. 3. When the ignition switch of the vehicle, which is the power switch, is turned off, the pointer is held at a base point position which is slightly minus the starting point of the dial by a magnetic action, and the pointer is held when the ignition switch is turned on. 3. The step motor type instrument according to claim 1 or 2, wherein is moved to the starting point position of the dial.