JP2001341553A - Driving method for indicating instrument - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a driving method for an indicating instrument that can effectively use the capacity of an engine control unit ECU on a vehicle, and can dispense with an arithmetic processing function in the indicating instrument for indicating travel- related information such as a travel speed and ensure a simple and low-cost structure thereof. SOLUTION: This indicating instrument 6 that uses, as an instrument movement, a cross coil type measuring instrument 1 comprising a bobbin 2 wound with exciting coils L1 and L2 and a rotating magnet 3 rotatably journaled in the bobbin 2, is positioned in a dashboard in front of the driver's seat of an automobile. The engine control unit ECU equipped with a computer CPU for control of the engine and control of other electric equipment is disposed, for example, under a side of the driver's seat in the automobile. The computer CPU receives an input of pulse signals of a frequency proportional, for example, to the travel speed, and generates and outputs signals capable of direct drive of the indicating instrument 6 after an operation of periodically measuring and counting the input measuring signals to produce digital signals indicative of the measurand. The indicating instrument 6 is thus capable of indication according to the measurand without its own arithmetic circuits dedicated to indication.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is used as an instrument movement which can be easily controlled digitally. For example, a measurement quantity such as a running speed or an engine speed for a vehicle is measured and instructed based on a frequency signal input proportional thereto. The present invention relates to a method for driving an indicating instrument to be operated.

2. Description of the Related Art In general, in this type of indicating instrument, a pointer fixed to a drive shaft end of the instrument movement is rotated in response to an input signal, and a numeral or a scaled character indicating a measured amount to be measured is provided. A measurement instruction is given by reading and comparing with the plate, and running-related information such as the running speed of the car, the engine speed or the remaining amount of fuel is provided by a speed sensor provided in the gear transmission, a pulse signal from an ignition device or a fuel tank The voltage signal from the resistive sensor inside the instrument is transferred to the meter device via the lead wire, and the measurement signal is converted into an instruction signal by an arithmetic processing circuit provided in the indicating instrument, and is indicated with desired indicating characteristics. It is configured as follows.

[0002] In addition, such an indicating instrument that performs pulse signal control for digitizing a processing circuit (control by a microcomputer) is used for an A / D processing of a traveling speed meter or an engine tachometer for a vehicle and a detection signal. It can also be used for fuel gauges and thermometers.

[0003]

However, in such an indicating instrument, a measurement signal obtained by measuring traveling-related information such as a traveling speed of a vehicle, an engine speed or a remaining fuel amount by various sensors is shaped into a waveform. Input directly to the arithmetic processing circuit in the instrument or use the engine control unit (EC
In U), the sensor signal is once converted to a digital signal, received as serial data by the indicating instrument, processed by an arithmetic circuit or data conversion circuit in the indicating instrument, and then the main body having the pointer is driven. Therefore, such an arithmetic processing circuit is required in the indicating instrument, which not only makes the indicating instrument expensive, but also inevitably increases the size of the circuit board and the size of the measuring instrument itself. The layout and the number of arrangements are restricted.

[0004] The present invention relates to an engine control unit (EC).
Attention is paid to the fact that the performance of the CPU (computer) used in U) is not sufficiently exhibited only by executing engine control and control of other electronic devices, and instructions to the CPU used in this ECU are issued. A function to drive the main body of the instrument and to generate a signal to directly drive the pointer and control the display value corresponding to the driving-related information is provided. It is intended to provide a very simple indicating instrument device without providing the arithmetic circuit.

According to the present invention, a drive signal is supplied to a plurality of excitation coils to drive a rotatably supported rotatable magnet, and a pointer fixed to a rotatable output shaft of the rotatable magnet is used for this purpose. In the driving method of the indicating instrument arranged below the hands and indicating the dial with the indicating scale,
The CPU of the vehicle's engine control unit (ECU)
A signal from a sensor that detects information related to the traveling of the vehicle is measured, and a drive signal is generated and output to a plurality of excitation coils of the indicating instrument so that the rotating magnet swings at an angle corresponding to the measured value. Does direct driving by the driving signal without further calculation.

According to the present invention, the indicating instrument is a movable magnet instrument in which a rotating magnet is driven by a pair of exciting coils for generating a cross magnetic field, wherein a driving signal from a CPU of the engine control unit is a measured value. , And is supplied to at least one of the pair of excitation coils.

According to the present invention, a PWM signal having a duty ratio corresponding to a measured value is supplied from the CPU of the engine control unit to each of the pair of exciting coils such that the duty ratio increases and decreases mutually. It is characterized by doing.

Further, according to the present invention, a drive signal from a CPU of the engine control unit is supplied to one of the pair of exciting coils as a PWM signal exhibiting a predetermined change corresponding to a measured value, and the other of the exciting coils is provided. Is characterized in that a voltage is supplied so as to generate a constant magnetic field.

According to the present invention, the indicating instrument is a step motor type instrument that drives a rotating magnet by a two-phase excitation coil,
The drive signal from U is a set of step drive rectangular signals exhibiting step drive corresponding to the measured value.

Further, according to the present invention, a CPU of an engine control unit (ECU) of a vehicle measures a signal from a sensor for detecting driving-related information of the vehicle, and indicates an indicating section of an indicating instrument disposed in front of a driver's seat of the vehicle. A driving signal for driving the indicator is generated and output, and the indicating instrument drives the indicating unit by the driving signal without performing further calculation.

DESCRIPTION OF THE PREFERRED EMBODIMENTS A pair of crossed excitation coils L1,
A cross-coil instrument 1 composed of a bobbin 2 on which L2 is wound and a rotating magnet 3 rotatably supported in the bobbin 2 is used as an instrument movement, and is fixed to a tip of a rotating output shaft of the rotating magnet 3. Guideline 4 and this guideline 4
An indicating instrument 6 is constituted by the dial 5 provided below and having an indicating scale M, and the indicating instrument 6 is arranged on a danche board in front of a driver's seat of an automobile.

An engine control unit ECU is disposed, for example, in the lower part of a driver's seat measurement area of a car, and a printed circuit board housed in a case is mounted with a computer CPU for controlling an engine and other electric components. The control signal is output to the engine ignition device and the fuel injection device through the wiring of the lead wire by connecting the connector.

The computer CPU inputs a pulse signal having a frequency proportional to the traveling speed detected by a rotation sensor such as an electromagnetic pickup or a Hall IC provided in a gear transmission, or uses an engine ignition control signal, or A / D conversion of a voltage signal proportional to the remaining fuel amount from the fuel sensor is performed, and a measurement signal inputting the measurement amount, which is various traveling-related information, is periodically measured or counted to calculate a digital signal representing the measurement amount. , Generates and outputs a signal that can directly drive the indicating instrument 6. As a result, the indicating instrument 6 can provide an instruction corresponding to the measured amount without having a dedicated arithmetic circuit for the instruction itself.

FIG. 1 is a system configuration diagram showing one embodiment of the present invention. An indicating instrument 6 is a rotating magnet 3 rotatably supported inside a resin bobbin 2 by using a cross coil type instrument as an instrument movement. And a pair of exciting coils L1 and L2 are wound so as to cross each other so as to surround the coil. The dial 4 is fixed to the tip of the rotary output shaft of the rotary magnet 3, and the dial 5 provided with the indicator graduation M disposed therebelow.
, And constitutes a traveling speedometer here.

The indicating instrument 6 is arranged on the dashboard in front of the driver's seat of the automobile, and indicates the current traveling speed by a rotation instruction position corresponding to the traveling speed of the pointer 4 with the display surface facing the driver. It is configured as follows. The actual device houses a printed circuit board in a resin case, mounts an instrument movement on this printed circuit board, and excites the excitation coils L1, L
2 is configured to be energized through a printed circuit board and an energizing terminal, and the printed circuit board is provided with a connector for connection to the outside.

The engine control unit ECU, which is arranged, for example, in the lower part of the driver's seat of the vehicle, executes an engine ignition control signal and a fuel control signal according to execution steps programmed in advance by a computer CPU mounted on a printed circuit board housed in the case. It generates and outputs control signals for various electrical components such as injection control signals. At the same time, a signal for driving the indicating instrument 6 is generated and output. Measurement signals from various sensors for measuring a traveling speed, an engine speed, a fuel remaining amount, and the like, which are various traveling-related information, are input. A signal that can directly drive the indicating instrument 6 is calculated and generated based on the signal. Such a drive signal may be used as it is when a minute current drive that can be directly driven by a calculation output from the computer CPU can be used. However, when a torque that can drive the instrument movement of the indicating instrument 6 cannot be obtained, the engine An amplifier circuit (driver circuit) for amplifying the current at the output stage of the computer CPU is provided on the internal printed circuit board of the control unit ECU, and the amplified drive signal is supplied directly to the excitation coils L1 and L2 of the indicating instrument 6. Alternatively, a current amplifying circuit is mounted on a printed circuit board inside the indicating instrument 6 and the engine control unit E
The drive signal output from the CU may be temporarily amplified by the amplifier circuit and then supplied to the excitation coils L1 and L2.

If the traveling speed meter is described, the engine control unit ECU inputs a pulse signal proportional to the traveling speed from a speed sensor and shapes the waveform. A PWM signal S1 whose duty ratio increases in proportion to the traveling speed and a PWM signal S2 whose duty ratio decreases (the respective duty ratios are in an inverted relationship as shown in FIG. 2) are generated and read. The power is supplied to each of the excitation coils L1 and L2 of the indicating instrument 6 via a wire.

As a result, a magnetic field having an angle corresponding to the traveling speed acts on the rotating magnet 3 of the indicating instrument 6, and the pointer 4 indicates the scale M of the dial 5 so that the traveling speed can be read. In this case, if the torque required to rotate the rotating magnet 3 cannot be sufficiently obtained, it can be dealt with by providing a current amplification circuit in the C-computer CPU output stage of the engine control unit ECU. If so, the indicator 6 can be easily prepared on a printed circuit board, and the indicator 6 itself can be constructed at a low cost without providing a dedicated arithmetic circuit.

The configuration in which the amplifying circuit is provided in the indicating instrument 6 will be described with reference to FIG. That is, a drive signal from the engine control unit ECU shown in FIG. 2 (a set of PWM signals S1, S
2) current is amplified by the transistors FET1 and FET2 mounted on the printed circuit board in the indicating instrument 6 and the exciting coil L is amplified.
1, L2. In this case, the frequency of the PWM signal is set to 16 kHz or more, which is outside the audible frequency range, thereby preventing unusual noise caused by coil vibration.

Also in this case, the indicating instrument 6 itself can be configured at a very low cost without having a dedicated expensive operation processing circuit in the indicating instrument 6, and since a complicated component structure such as circuit components is not required, The indicating instrument 6 itself can be configured to be small and thin, and the ability of the computer CPU of the engine control unit ECU, which has become highly functional, can be used effectively. Such a structure is not a structure in which many types of instruments are driven in parallel by a single computer, but is effective when applied to so-called soft bikes, particularly among motorcycles in which indicating instruments are mounted with a few types of instruments. is there.

The drive signals supplied to the excitation coils L1 and L2 are, as shown in FIG. 2, PWM signals S1 and S2 having a duty ratio in an inverting relationship with each other. As shown in the figure, the duty ratio of the PWM signal S1 to the coil L1 is constant until the neutral point and decreases thereafter, and the duty ratio of the PWM signal S2 to the coil L2 is substantially equal to the neutral point of the swing angle. The relationship may be such that increases and becomes constant thereafter. Sufficient indicating characteristics can also be obtained by such control waveforms.

FIG. 5 shows that one coil L1 has a low voltage VC.
C1 always supplies a constant current, and the other coil L2 has a computer C of the engine control unit ECU.
The PU applies a PWM signal whose duty ratio is in an inverting relationship shown in FIG.
They are connected by ET4 as shown in the figure. With this configuration, a magnetic field whose direction of generation is reversed is generated in the coil L2 with respect to a constant magnetic field that always flows through the coil L1,
As a result, a rotating magnetic field corresponding to the traveling speed is generated as a combined magnetic field, and the rotating magnet 3 can be driven. Even with such a structure, the indicating instrument 6 does not require a dedicated arithmetic processing circuit, and only a current amplifier circuit is prepared, so that a similarly inexpensive configuration can be achieved.

In the embodiment described above, a cross-coil type instrument is adopted as the instrument movement. However, a stepping motor can be used as the instrument movement. As a stepping motor, a so-called PM type is simple, and the stepping motor is easily digitally controlled and is effective for such direct control. The diode connected in parallel with the exciting coil L and the transistor FET is easy to absorb surges, and is particularly effective when the power supply noise signal is large.

The structure of a stepping motor is basically a general one in which a rotary magnet is step-driven through a yoke having pole teeth by a drive signal to two exciting coils L1 and L2. Is fixed and the traveling speed can be instructed by the structure as shown in FIG. 1, and as a driving method, the exciting coil L shown in FIG.
By providing a power supply control circuit to the output stage of the computer CPU in the engine control unit ECU or on a printed circuit board inside the case of the indicating instrument 6,
In this case, the size and thickness can be reduced and the cost can be reduced without providing a dedicated arithmetic processing circuit.

As shown in the figure, this energization control circuit includes transistors FET1 to FET4 at both ends of the exciting coil L.
A drive current flows in both directions in response to a signal input to the transistor, and a computer CPU generates and supplies signals to the bases of the transistors FET1 to FET4. Two exciting coils L having the configuration shown in the figure are prepared, and in practice, the rotary magnet is step-driven by supplying a phase signal to the exciting coils L1 and L2.

The drive signal waveforms to the excitation coils L1 and L2 can be freely selected for one-phase excitation, two-phase excitation, or a combination of these for one- or two-phase excitation commonly known in this type of stepping motor drive. Fig. 7 shows the waveform of each phase excitation.
Indicated by The drive signal waveform to the excitation coils L1 and L2 is
Each of the one-phase excitation, the two-phase excitation, and the one- or two-phase excitation is represented by bidirectional energization to a coil as shown in the figure. Each signal can be controlled by the ON / OFF operation of the transistors FET1 to FET4. For example, in the case of one-phase excitation, rectangular signals are alternately output to the excitation coils L1 and L2 as shown in FIG.
The rotating magnet performs step driving according to the signal, and can be adopted as the simplest driving method. In this case, since the pointer 4 is intermittently moved, the pointer 4 is driven in a reduced manner from the rotary output shaft to the pointer shaft supported in parallel via the reduction gear, so that the pointer 4 can be smoothly supported. Things. The structure for smoothing the movement of the pointer 4 with such a reduction gear mechanism interposed therebetween is a two-phase excitation type or 1-2 type.
Although it can be applied to any of the phase excitation methods, the above-mentioned cross-coil type instrument can also be adopted as a structure for reducing the hysteresis error due to the residual magnetism of the so-called magnetic shield case (which can be reduced in angle). .

As shown in the figure, the signal waveform in the two-phase excitation system is such that a drive signal is always supplied to both coils L1 and L2, and an intermittent movement such as one-phase excitation is slightly eliminated. . As shown in the figure, in the 1-2-phase excitation system, a part of the signal waveform of the 1-phase excitation system is superimposed as in the 2-phase excitation system to slightly increase the smoothness. In the method of the present invention, the amount of change in the speed signal that is determined and output periodically according to the traveling speed is sequentially increased or decreased from the initial value of the instruction starting point to indicate the current value, and the current value is indicated. Step drive is performed by the number of steps corresponding to the difference, including the direction of increase / decrease from the immediately preceding value.

Although a simple step drive with a step drive waveform as shown in the figure is simple in control, a so-called micro-step drive system is employed in order to obtain a smoother movement without intervening a reduction gear. May be. In this micro-step drive, instead of the rectangular wave signal shown in FIG. 7, an effective value is supplied as a signal that changes into a SIN or COS waveform shape, and PW
It can be configured to change the effective value by the M signal (frequency at which the rotating magnet cannot follow each pulse).
In the case of a stepping motor, the position of the rotating magnet when the power is turned on becomes the initial value, and the step driving is performed from there. Therefore, when the power switch is turned on or off, the rotating magnet (that is, the pointer) is forcibly moved in one direction. Rotate
It can be dealt with by stopping with the stopper at the starting position and initializing with this point as the starting point.

Also in the case of such a configuration, the computer CPU of the engine control unit ECU takes in the traveling speed sensor signal and performs an arithmetic processing by an internal arithmetic program to generate a drive signal to the indicating instrument 6. Since the indicating instrument 6 itself does not have an arithmetic circuit for arithmetically processing a sensor signal to generate a drive signal, and only needs to include, for example, a current amplifier circuit (driver) for obtaining a drive torque, The high-performance computer CPU of the engine control unit ECU can be effectively used, and the configuration of the indicating instrument 6 can be extremely simplified.

In the embodiment described above, the traveling speed is taken as an example of the vehicle traveling-related information. However, various information such as the engine speed, the remaining fuel amount, and the traveling distance are similarly used by the engine control unit ECU. , And the indicating instrument 6 simply uses the engine control unit ECU.
It is only necessary to drive the hands 4 in response to the drive signal generated by the above, and the structure of the indicating instrument 6 uses an instrument movement using an exciting coil such as a cross-coil instrument or a stepping motor instrument as in the embodiment. Even if a digital display such as a liquid crystal display is used, if the drive signal directly applied to each display segment is generated by the computer CPU of the engine control unit ECU, the indicating instrument 6 The device itself can adopt a simple configuration that only has a display or a driver for amplifying voltage or current as required.

The indicating instrument 6 having such a configuration can be obtained by simply transferring a drive signal generated by the computer CPU in the engine control unit ECU through a lead wire, and a plurality of kinds of indicating instruments 6 are prepared. In such a case, a configuration in which signals are transferred in parallel to each of the indicating instruments 6 can be the simplest configuration. The drive signal is once converted into serial data by a plurality of types of indicating instruments 6, and each signal is converted to a corresponding indicating instrument 6 at an input stage in the indicating instrument 6.
Engine control unit EC if configured to distribute to each
The signal transfer line from U can be simplified.

As described above, the present invention measures and calculates various types of vehicle travel-related information using a high-performance computer CPU of an engine control unit ECU mounted on a vehicle.
By generating a direct drive signal to the indicating instrument and transferring it to the indicating instrument, the indicating instrument itself does not have an arithmetic processing circuit for calculating detection signals of various related information by sensors, The processing capability of the computer CPU of the engine control unit ECU can be effectively used, and accordingly, the indicating instrument itself can be simplified and inexpensively configured without having a dedicated arithmetic processing circuit.

[Brief description of the drawings]

FIG. 1 is a circuit diagram showing one embodiment of a method for driving an indicating instrument according to the present invention.

FIG. 2 is a waveform explanatory diagram showing a drive signal waveform of the configuration shown in FIG. 1 of the present invention.

FIG. 3 is a circuit diagram showing another embodiment for implementing the method of driving the indicating instrument according to the present invention.

FIG. 4 is a waveform explanatory diagram showing another example of a drive signal waveform for implementing the indicating instrument driving method of the present invention.

FIG. 5 is a circuit diagram showing still another embodiment for implementing the method of driving the indicating instrument according to the present invention.

FIG. 6 is a circuit diagram showing still another embodiment for implementing the method of driving the indicating instrument according to the present invention.

FIG. 7 is a waveform explanatory diagram showing a drive signal waveform of the embodiment shown in FIG. 6 of the present invention.

[Description of Signs] ECU Engine Control Unit CPU Computer Constituting Engine Control Unit ECU 1 Cross-Coil Meter 2 Resin Bobbin 3 Rotating Magnet 4 Pointer 5 Dial 6 Indicator Meter M Scale L1, L2 Excitation Coil FET Transistor

Claims (6)

[Claims] A driving signal is supplied to a plurality of excitation coils to drive a rotatably supported rotatable magnet, and a pointer is provided below the pointer by a pointer fixed to a rotary output shaft of the rotary magnet. In a method of driving an indicating instrument for indicating a dial subjected to the above, a CPU of an engine control unit (ECU) of the vehicle measures a signal from a sensor for detecting traveling-related information of the vehicle, and controls a plurality of the indicating instruments. A driving signal is generated and output to the exciting coil such that the rotating magnet swings at an angle corresponding to the measured value, and the indicating instrument performs direct indicating driving by the driving signal without performing further calculation. How to drive the indicating instrument. 2. The moving instrument of claim 1, wherein the indicating instrument is a movable magnet instrument that drives a rotating magnet by a pair of exciting coils for generating a cross magnetic field.
2. The method according to claim 1, wherein the drive signal from U is a PWM signal having a duty ratio corresponding to a measured value, and is supplied to at least one of the pair of excitation coils. 3. A method for supplying a PWM signal having a duty ratio corresponding to a measured value from a CPU of the engine control unit to each of the pair of exciting coils such that the duty ratio increases and decreases mutually. 3. The method for driving an indicating instrument according to claim 2, wherein: 4. A driving signal from a CPU of the engine control unit, wherein the driving signal exhibits a predetermined change corresponding to a measured value.
3. The method according to claim 2, wherein a WM signal is supplied to one of the pair of exciting coils and a voltage is supplied to the other of the exciting coils so as to generate a constant magnetic field. 5. The step indicator is a step motor type instrument that drives a rotating magnet by a two-phase excitation coil, and a drive signal from a CPU of the engine control unit exhibits a step drive corresponding to a measured value. 2. The method for driving an indicating instrument according to claim 1, wherein the signal is a set of rectangular signals for step driving. 6. An engine control unit (ECU) for a vehicle.
CPU, measures a signal from a sensor that detects travel-related information of the vehicle, generates and outputs a drive signal for driving an indicating unit of an indicating instrument disposed in front of the driver's seat of the vehicle, and the indicating instrument A method for driving an indicating instrument, wherein the indicating unit is driven by the driving signal without performing further calculations.