JPH0149882B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a vehicle travel guidance system that suppresses errors in the direction detected by a direction sensor that detects a reference direction to the vehicle due to disturbance of the earth's magnetic field when a defogger is activated. .

Conventionally, commercially available magnetic compass bearings have been widely used when driving a vehicle toward a planned destination to check whether the direction of travel of the vehicle is deviating from the direction of the destination. (Magazine DRIVER) Extra edition DELUXE, latest car supplies catalog (Publication date: March 10, 1978, Publisher:
(Choushu Publishing), see page 117). However, since this magnetic direction meter is mechanical, it has drawbacks such as an unstable pointer, making it difficult to read the direction, and its mechanical structure making it difficult to see from the side.

In order to improve this drawback, the applicant of the present application has proposed an orientation sensor that detects the reference orientation of the vehicle (Japanese Patent Application No. 1983-6057). This orientation sensor is constructed as shown in FIG. In the figure, 1 is a Hall motor, which is connected to a control circuit 2 that rotates at a constant speed. Further, a sensor coil 4 is attached to the rotating shaft 3 of the Hall motor 1 and rotates integrally therewith. This sensor coil 4 is a U-shaped conductor with an open end.
This is placed in the earth's magnetism, and vertical coil pieces 4a and 4b are arranged in the earth's magnetism in orthogonal directions. Slip rings 5 and 6 are connected to both ends of this sensor coil 4, respectively.
Brushes 7 and 8 are brought into contact with these, supplying half-wave alternating current to an amplifier 9 connected to these, and obtaining a full-wave alternating current output signal at the output side of amplifier 9.
In addition, the Hall motor 1 transmits the rotational position of the rotor (i.e., the rotational position of the rotating shaft 3 and sensor coil 4).
Obtain a signal to detect.

Further, an azimuth calculation circuit shown in FIG. 2 is connected to this azimuth sensor. In the figure, numeral 10 denotes an azimuth detection signal generator which shapes the output of the amplifier 9 into a waveform and outputs it, and an alternating signal as shown in FIG. 3a is obtained at its output. This signal is the coil piece 4
This is an alternating voltage with a predetermined phase obtained in accordance with the direction of the vehicle depending on the rotation of a and 4b. This alternating signal is applied to the zero cross comparator 11, and the third
The signal is converted into a signal having the waveform shown in FIG. On the other hand, the rotational position signal from the Hall motor 1 is applied to a rotational position signal generator 13 having a waveform shaping function, and a signal as shown in FIG. 3c is obtained at its output side. This signal is the delay circuit 1
4, resulting in the signal shown in FIG. 3d, which is applied to the reset input terminal of the reset flip-flop 12. In this flip-flop 12, at the rising edge of each of the above signals, as shown in FIG.
A pulse is formed and is applied to one input terminal of the next AND gate 15. this
A clock pulse is constantly inputted to the other input terminal of the AND gate 15 from a high frequency reference signal generator 16, and the signal shown in FIG. 3f is obtained at its output side. This clock pulse is counted by the counter 17 every time there is the reset input, and the count signal is temporarily read into the register 18, and the azimuth angle is read from the register 18 using the signal from the rotational position signal generator 13 as a set input signal. A signal corresponding to θ is output and displayed on the display 19.

By the way, it is preferable that the above-mentioned orientation sensor is installed outside the vehicle interior above the geomagnetic sensor, but if it is installed outside the vehicle, it will protrude onto the surface of the vehicle body and may interfere with car washing, be damaged by mischief, or pose a safety risk. Problems may arise. Therefore, if an orientation sensor is to be installed in the vehicle interior, it may be installed in the rear parcel shelf behind the seat due to space usage considerations.

However, when installed in a rear parcel shelf, if a rear differential auger is installed on the rear window glass, a magnetic field will be formed around the rear window glass when the defogger is activated, which may disturb the earth's magnetic field. Therefore, there is a risk that erroneous detection may occur depending on the orientation sensor.

The present invention has been made to improve this problem, and includes a correction means that generates a magnetic field of the same magnitude in the opposite direction to the magnetic field generated by the rear defogger, thereby suppressing detection errors. The purpose of the present invention is to provide a vehicle travel guidance device that provides

Embodiments of the invention will be described below with reference to the drawings.

Figure 4 is a front view showing the main parts of the rear of the vehicle 20;
The figure is also a plan view, and a plurality of hot wires 22 constituting a rear defogger are buried in parallel in the rear window glass 21, and a current in the direction of arrow A is supplied to these wires. Further, the above-mentioned rear parcel shelf 23 is installed at a position facing the rear window glass 21, and a non-magnetic case 24 containing the above-mentioned orientation sensor is attached near the center portion above this. Furthermore, an electromagnet 25 is installed on the case 24 to correct disturbances in the earth's magnetic field during the operation of the defogger. Furthermore, this electromagnet 2
5 is also non-magnetic case 2, similar to the orientation sensor above.
It is housed within 6.

With this configuration, there is no need to defrost, and when no current is flowing through the hot wire 22 of the rear defogger, the earth's magnetism travels almost straight to the sensor coil of the orientation sensor in the vehicle interior. Therefore, there is no error in the detected direction. However, in order to defrost the heat wire 22,
When a current is passed through, a magnetic field is generated around the plurality of hot wires in the direction of arrow B, as shown in FIG.
Further, this magnetic field acts in the direction of arrow C on the orientation sensor housed in the case 24, as shown in FIG. Therefore, if a magnetic field of equal magnitude in the opposite direction to the direction of arrow C is formed by passing a current through the electromagnet 25, the magnetic field generated by the hot wire 22 will be equal to the magnetic field caused by the electromagnet 25. , so that error-free direction detection can be performed. In this case, the direction of the electromagnet 25 and the magnitude of the current flowing through it are determined based on data obtained experimentally in advance about disturbances in the earth's magnetic field caused by the rear defogger.

On the other hand, since the earth's magnetic field compensation due to the electromagnetic field need only be performed when current is passed through the hot wire 22 of the rear defogger, the circuit shown in FIG. 6 is used. This is a conventional circuit in which an ignition switch 28, a defogger switch 29 and a hot wire 22 are connected in series to a battery 27, but the electromagnet 25 is connected in parallel to the hot wire 22.

In such a circuit, current flows through both the hot wire 22 and the electromagnet 25 at the same time as the defogger switch 29 is closed, and the disturbance caused by the action of the geomagnetic hot wire 22 as described above can be corrected by the action of the electromagnet 25.

As explained above, the present invention provides an azimuth sensor that is placed near a hot-wire defogger and detects a reference orientation for a vehicle based on the magnitude and direction of a current flowing through a sensor coil placed in the earth's magnetism; While the defogger is operating, a correction means is installed that generates a magnetic field of the same magnitude in the opposite direction to the magnetic field generated by the defogger near the orientation sensor, and the defrost is removed by canceling the magnetic field by the defogger. Direction detection using the internal direction sensor can be performed without error, and since the correction means is energized only while the defogger is operating, energy can be saved.

[Brief explanation of drawings]

Fig. 1 is a perspective view of the azimuth sensor applied by the applicant, Fig. 2 is a azimuth calculation circuit diagram that similarly calculates the output of the azimuth sensor, Figs. 3 a to f are waveform diagrams of various parts of the circuit, and Fig. 4 The figure is a front view showing a main part at the rear of a vehicle in which a direction sensor according to an embodiment of the present invention is installed, FIG. 5 is a plan view of the same main part, and FIG. 6 is a circuit diagram for correcting geomagnetic disturbances. 20...Vehicle, 22...Heating wire, 23...Rear parcel shelf, 24...Nonmagnetic case, 25...Geomagnetic correction means (electromagnet).

Claims (1)

[Claims] 1. An azimuth sensor that is placed near the hot-wire defogger and detects the reference orientation of the vehicle based on the magnitude and direction of the current flowing through a sensor coil placed in the earth's magnetism, and while the defogger is in operation, A vehicle travel guidance device comprising: a correction means for generating a magnetic field having the same magnitude in a direction opposite to the magnetic field generated by the defogger near the azimuth sensor.