JPS6128922B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention improves the device configuration by rotating a geomagnetism detection section by an AC motor and using a multiphase AC signal supplied to the AC motor as a rotational position detection signal and an error correction signal due to vehicle body magnetism. The present invention relates to a simplified vehicle orientation detection device.

2. Description of the Related Art Conventionally, as a direction detection device used to indicate the direction of travel of a vehicle, there is, for example, one shown in FIG.

In FIG. 1, a core 2 rotated at a constant speed by a motor 1 is installed in a fixed coil 3 for detecting geomagnetism, and this core 2 is rotated relative to the fixed coil 3 so that an arm portion 2a of the core 2 is rotated at a constant speed. A geomagnetic detection signal (AC signal) E _N induced in the fixed coil 3 when crossing the direction of the magnetic field due to geomagnetism is extracted. on the other hand,
A semicircular rotating plate 5 is attached to the rotating shaft 4 of the core 2, and a photocoupler 6 is installed to output a rotational position detection signal E _S that becomes a rectangular wave when light is blocked by passing through the rotating plate 5. As shown, when the arm portion 2a of the core 2 rotates to a position perpendicular to the direction of geomagnetism, the polarity of the geomagnetism detection signal E _N switches from positive to negative or from negative to positive. At the timing of switching, for example, the timing when the polarity switches from negative to positive, the rotational position detection signal E
The phase difference θ when _S rises is detected, and this phase difference θ indicates the traveling direction of the vehicle (west-northwest) with respect to a predetermined direction, for example, west, so this phase difference θ
By displaying the direction based on the direction, the direction in which the vehicle is traveling can be determined.

By the way, in general, vehicles generate body magnetism that has a unique magnitude and direction for each vehicle, and when the above-mentioned direction detection device is mounted on the vehicle, this vehicle body magnetism acts on the direction detection device, and the geomagnetic detection signal E _N now includes errors due to vehicle body magnetism.

Therefore, when installing a direction detection device on a vehicle, a permanent magnet or an electromagnet was conventionally installed near the rotating core 2 to cancel out the vehicle body magnetism in order to correct the error caused by the vehicle body magnetism. The inventors of the present application have found that the work of positioning so as to cancel the magnetism is extremely complicated, and that it is not possible to stably obtain a highly accurate geomagnetic detection signal E _N due to positional deviation after adjustment, changes in magnetic force, etc. proposed a direction detecting device as shown in FIG. 3, which is capable of correcting errors caused by vehicle body magnetism using a circuit.

In FIG. 3, 7 is a phase lock loop circuit (PLL) that converts the rotational position detection signal (rectangular wave signal) E _S into an AC signal of the same frequency; 8 is a phase lock loop circuit (PLL) that converts the rotational position detection signal (rectangular wave signal) _E For example, 9 and ₁₀ are inversion circuits that invert the AC signals EX _{and EY} and generate AC signals _-EX and _-EY with opposite phases; 1;
1 and 12 are AC signals E _X and -E _Y and E _Y and -E _Y
14 is _a volume for outputting _{predetermined alternating} current signals _E This is a correction circuit that outputs a true geomagnetism detection signal E _N from which errors due to vehicle body magnetism have been removed.

_According to _this device, as shown in the AC vector diagram in FIG. By creating a composite vector of the signals _E.sub.X and _E.sub.Y , they are cancelled, and the error signal _E.sub.B is corrected to eliminate the phase .theta. which occurs between the true geomagnetic direction detection signal _E.sub.N.

As described above, according to the device proposed by the inventors of the present application, the AC signal E by the volumes 11 and 12 is
By adjusting _X and E _Y , it has become possible to easily correct errors caused by vehicle body magnetism.

By the way, in the device shown in FIG. 3, a photocoupler for detecting the rotational position detection signal E _S is provided in the geomagnetism detection section, and _AC signals _E to get
Although this is obtained using a PLL circuit, since the above-mentioned geomagnetism detection section is installed protruding from the outside of the vehicle, it is desirable to make it as compact as possible from the point of view of design and to reduce running resistance. Since it is an in-vehicle component, it is desirable to keep it simple from the viewpoint of durability and reliability, and the present invention focuses on this point.

The present invention has been made in view of the above, and in order to simplify the configuration, any two of the AC signals supplied to each of the field coils of the motor that drives the rotating conductor of the geomagnetism detector are used. The geomagnetism detection signal is corrected using the above-described method, and the direction is calculated from the corrected geomagnetism detection signal and any one of the AC signals.

Hereinafter, the present invention will be explained based on the drawings.

FIG. 5 is a perspective view showing an embodiment of the mechanism used in the geomagnetism detection device of the present invention. First, to explain the configuration, the core 2 is connected to an alternating current signal motor 15 by a rotating shaft 4, and a fixed coil 3 for geomagnetic detection.
The AC motor 1 rotates at a constant speed and is not equipped with a photocoupler or other means for extracting a rotational position detection signal.
5, determined by the core 2 and fixed coil 3,
In particular, the only part that protrudes to the outside of the vehicle body is the geomagnetism detection section consisting of the core 2 and the fixed coil 3, and the mechanism section can be significantly miniaturized.

FIG. 6 shows a drive circuit for the AC motor 15. The AC motor 15 has a polarized rotor 16 using a permanent magnet as a rotor, and a 90° motor around the polarized rotor 16. Four independent field coils 17a, 17b, and 18a with different phases by
18b and facing field coils 17a and 1.
7b, 18a, and 18b are connected in series.
This AC motor 15 is known as a so-called thyristor motor (non-commutator motor), and is designed to vary the phase of AC signals applied to field coils 17a, 17b and 18a, 18b by a predetermined phase, for example, 90 degrees. A rotating magnetic field is created, and the polarized rotor 16 rotates synchronously following this rotating magnetic field.

As a power source for the AC signal motor 15 having such a structure, an inverter device 20 is provided which converts the DC voltage from the battery 19 into AC signals _EX , E _Y having different phases.
AC signals E _X and E _Y having a phase difference of .degree. are supplied to the AC motor 15.

In addition, in the AC motor 15, the polar rotor 16
For the number of poles N (N=an integer of 2, 3, 4, . . . ), the number of field coils to be arranged is 2Z, and is not limited to the embodiment shown in FIG. Further, as the geomagnetism detection section, a rotating coil may be used instead of the core 2 and the fixed coil 3.

FIG. 7 equivalently shows an embodiment of the geomagnetism detection signal correction circuit used in the present invention using the AC motor 15 as described above, and the AC motor _{15 is}
The AC sources 21 _and 22 that output the AC signals _E
AC voltages _{E ,} 24 are added to _the geomagnetism detection signal _EN .

Further, the AC voltage E _Y is outputted from the AC source 22 as a rotational position detection signal E _S . This signal E _S may be an AC signal E _X from the AC source 21.

Next, the operation will be explained.

First, to explain the operation of the correction circuit shown in FIG. 7, for example, with the vehicle facing a predetermined direction, for example, north,
When driven by the supply of _X and E _Y , the constant speed rotation of the core 2 provided in the fixed coil 3 causes the AC motor 1
Geomagnetic detection signal E with a frequency matching the rotation speed of 5
This E _{N '} signal includes an error signal E _S due to the vehicle body magnetism, and as shown in the AC vector diagram of Fig. 8, the E _N ' signal is an error signal E _B and the AC signal E _N of the direction to be detected, and has a phase difference θ between the vector E N and the AC signal E _N of the direction to be detected.

On the other hand, AC signals E _X and E _Y to be added to the E _N ' signal
By adjusting the volumes 23 and 24, _-EX ~
It can be adjusted within the range of +E _Y , -E _Y to +E _Y , and a vector of composite signal E _B ' can be created at an arbitrary phase.

Therefore, the geomagnetic detection signal E of the geomagnetic power generation section 25
For example, adjust the volumes 23 and 2 while looking at the direction indicator etc. so that _N ' becomes the direction signal E _N to be detected.
4 to adjust the alternating current signals _EX and E _Y. Assuming that the direction to _be detected _is obtained by adjusting the _{alternating current} signals _E
It is a vector with the opposite direction and the same magnitude as the vector of _B , and this resultant vector E
_B ' cancels out the vector of the error signal E _B , that is, the error signal E _B due to the vehicle body magnetism, so that the phase error of the E _N ' signal with respect to the azimuth signal E _N to be detected becomes zero.

On the other hand, direction detection using the correct geomagnetic detection signal E _N obtained by removing errors caused by vehicle body magnetism as described above is possible by detecting one of the AC signals supplied to the AC motor as shown in Figure 9. The rotational position detection signal E _S is used as a geomagnetic detection signal E _N when the vehicle is placed in a predetermined direction, for example, toward the west.
For example, when the vehicle is turned west-northwest, the rotational position detection signal E _S and the geomagnetic detection signal E _S match in phase, as shown in the figure. Since a phase difference θ occurs between E _N and E N , by detecting this phase difference θ and displaying an azimuth corresponding to the phase difference θ with respect to the reference azimuth, it is possible to display that the vehicle is facing west-northwest.

As explained above, according to the present invention, the configuration is such that the geomagnetism detection section is rotated at a constant speed by the driven AC motor by supplying a plurality of AC signals having a predetermined phase difference, and the signals are supplied to the AC motor. outputs one of the AC signals as a rotational position detection signal for direction detection, and adds the phase of the geomagnetic detection signal when the vehicle is oriented in a predetermined direction to the AC signal supplied to the AC motor. As a result, the detection mechanism for the rotational position detection signal used for direction detection is no longer necessary, making it possible to simplify and downsize the structure of the geomagnetism detection unit.Also, the AC motor has a non-commutator structure. This greatly improves the durability of the device, and furthermore, the correction circuit itself is extremely simple, making it less expensive and more reliable. The effect is that it is easy to do.

[Brief explanation of the drawing]

Fig. 1 is a perspective view showing the structure of a conventional geomagnetism detection unit, Fig. 2 is a signal waveform diagram showing the principle of direction detection by the conventional device, and Fig. 3 is a correction device proposed by the inventors of the present application. Fig. 4 is an AC vector diagram showing the correction principle by the device shown in Fig. 3;
FIG. 5 is a perspective view showing an embodiment of the geomagnetism detection section used in the present invention, FIG. 6 is a circuit diagram showing the AC motor in FIG. 5 and its power supply, and FIG. 7 is a correction circuit used in the present invention. FIG. 8 is an AC vector diagram showing the principle of correction by the circuit of FIG. 7, and FIG. 9 is a signal waveform diagram showing the principle of direction detection according to the present invention. 1...Motor (DC motor), 2...Core, 3
... Fixed coil, 4 ... Rotating shaft, 5 ... Rotating plate,
6... Photo converter, 7... PLL circuit, 8... Phase shift circuit, 9, 10... Inverting circuit, 11, 12, 2
3, 24... Volume, 13, 25... Geomagnetic power generation section (detection section), 14... Correction circuit, 15...
AC motor, 16...Polarized rotor, 17, 17
a, 17b, 18, 18a, 18b... Field coil, 19... Battery, 20... Inverter device, 21, 22... AC source.

Claims (1)

[Claims] 1. A detection means for detecting a geomagnetic signal from an alternating current voltage induced by the geomagnetism acting on a rotating conductor, and supplying an alternating current signal with a predetermined phase difference to each of a plurality of field coils to rotationally drive the rotating conductor. Create a vector signal corresponding to a vector having a component in a predetermined direction among arbitrary directions based on two alternating current signals having a phase difference mutually supplied to a motor and a field coil of this motor,
a correction means for correcting the geomagnetic signal by combining the geomagnetic signal and the vector signal; and a correction means based on the signal obtained by the correction means and an alternating current signal to be supplied to any one field coil of the motor. 1. A vehicle orientation detection device, comprising: calculation means for calculating an orientation and outputting an orientation signal.