![\"speedmater_en\"](\"https:\/\/katuhito.info\/wp-content\/uploads\/2022\/12\/combi_000_en.png\")
<\/a><\/p>\nThe combination meter has a speedometer, tachometer, fuel gauge, water temperature gauge, various indicators, etc. arranged in one panel so that the driver can check the operating status of each part of the car at a glance. A combination meter generally has a structure that mechanically indicates numerical values and quantities with pointers.<\/p>\n
Table of Contents<\/strong><\/h4>\n\n- Electric speedometer<\/a><\/li>\n
- Vehicle speed sensor<\/a><\/li>\n
- Mechanism of speed display<\/a><\/li>\n
- Working principle of cross-coil meter<\/a><\/li>\n
- Cumulative mileage<\/a><\/li>\n<\/ul>\n
Electric speedometer<\/strong><\/h4>\nThe electric speedometer is a cableless speedometer that does not use cables, and consists of a vehicle speed sensor that detects vehicle speed, a cross-coil speedometer, and a pulse motor-type odometer and trip meter. It is installed and the speedometer is operated by the electric signal obtained from it.<\/p>\n
![\"Figure](\"https:\/\/katuhito.info\/wp-content\/uploads\/2022\/12\/combi_001_en.jpg\")
<\/a>Figure 1: Electronic speedometer<\/p><\/div>\n
The meter section in Fig. 1 includes a cross-coil speedometer that moves the hands, an electronic circuit that applies current to the cross-coil, and an odometer and trip meter that integrate the distance traveled.<\/p>\n
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Vehicle speed sensor<\/strong><\/h4>\nMany vehicle speed sensors of electric speedometers use a magnetic induction element (MRE: Magnetic Resistance Element).<\/p>\n
![\"Figure](\"https:\/\/katuhito.info\/wp-content\/uploads\/2022\/12\/combi_002_en-300x224.jpg\")
<\/a>Figure 2: Magnetoresistive element (MRE) speedometer sensor<\/p><\/div>\n
As shown in Fig. 2, this sensor consists of a hybrid IC with a built-in magnetoresistive element and a magnet ring driven by the drive gear (final speed detection) on the output shaft of the transmission.<\/p>\n
![\"Figure](\"https:\/\/katuhito.info\/wp-content\/uploads\/2022\/12\/combi_003_en-300x151.jpg\")
<\/a>Figure 3: Properties of a magnetoresistive element (MRE)<\/p><\/div>\n
A magnetoresistive element (MRE) has the property that the magnitude of resistance changes as the magnetic lines of force change with respect to the direction of the current, as shown in Fig. 3.<\/p>\n
![\"Figure](\"https:\/\/katuhito.info\/wp-content\/uploads\/2022\/12\/combi_004_en-300x156.jpg\")
<\/a>Figure 4: Vehicle speed sensor structure<\/p><\/div>\n
In addition, since the MRE is arranged around the multipolar magnet ring as shown in FIG. 4, the direction of the magnetic lines of force changes according to the rotation speed of the ring, and a pulse signal is generated.<\/p>\n
This signal is converted to a digital signal by the comparator and transistor in the amplifier and sent to the electronic circuit of the speedometer from the \u2461 terminal of (2) in Fig. 4.<\/p>\n
The output of the vehicle speed sensor is a signal with a period of 4 pulses per rotation of the magnet ring.<\/p>\n
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Mechanism of speed display<\/strong><\/h4>\nIn the cross-coil speedometer, when the signal from the vehicle speed sensor is input to the electronic circuit as shown in Fig. 5, this IC counts the pulses of the signal, and the magnitude and direction of the current flowing through the cross-coil according to the vehicle speed. is changed, and the needle (magnet) is swung in the direction of the synthetic magnetic field formed thereby to display the speed.<\/p>\n
![\"Figure](\"https:\/\/katuhito.info\/wp-content\/uploads\/2022\/12\/combi_005_en-300x144.jpg\")
<\/a>Figure 5: Cross-coil speedometer configuration<\/p><\/div>\n
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Working principle of cross-coil meter<\/strong><\/h4>\n![\"Figure](\"https:\/\/katuhito.info\/wp-content\/uploads\/2022\/12\/combi_006_en-300x145.jpg\")
<\/a>Figure 6: Cross-coil meter<\/p><\/div>\n
A cross-coil meter has two coils wound 90 degrees off-set on the outside of a magnetic rotor, as shown in Figure 6.<\/p>\n
As a result, from the electronic circuit, the magnitude and direction of the current flowing through the coils L1 and L2 change like a sinusoidal waveform in conjunction with the vehicle speed. Actually, the graph of the relationship between the current and the vehicle speed is obtained by offsetting the phase of the waveform by 90 degrees as shown in (1) of FIG.<\/p>\n
![\"Fig.](\"https:\/\/katuhito.info\/wp-content\/uploads\/2022\/12\/combi_007-1_en-300x162.jpg\")
<\/a>Fig. 7 (1): Relationship between coil current and vehicle speed<\/p><\/div>\n
In the cross-coil type meter, the direction and magnitude of the magnetic field generated by each coil are changed, and the pointer indicates the direction of one magnetic field or a composite magnetic field of two-way magnetic fields as shown in Fig. 7 (2) A to D. That is, it points in the direction of the vector in which the forces are balanced.<\/p>\n
![\"Figure](\"https:\/\/katuhito.info\/wp-content\/uploads\/2022\/12\/combi_007-2_en-300x148.jpg\")
<\/a>Figure 7(2): Pointer direction at each speed<\/p><\/div>\n
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Cumulative mileage<\/strong><\/h4>\n![\"Figure](\"https:\/\/katuhito.info\/wp-content\/uploads\/2022\/12\/combi_008_en-300x193.jpg\")
<\/a>Figure 8: Pulse motor drive circuit<\/p><\/div>\n
The driving circuit shown in Fig. 8 integrates the signal from the vehicle speed sensor with the rotating pulse motor and odometer to determine the traveled distance.<\/p>\n
Electric speedometer<\/strong><\/h4>\nThe electric speedometer is a cableless speedometer that does not use cables, and consists of a vehicle speed sensor that detects vehicle speed, a cross-coil speedometer, and a pulse motor-type odometer and trip meter. It is installed and the speedometer is operated by the electric signal obtained from it.<\/p>\n
<\/a>Figure 1: Electronic speedometer<\/p><\/div>\n
The meter section in Fig. 1 includes a cross-coil speedometer that moves the hands, an electronic circuit that applies current to the cross-coil, and an odometer and trip meter that integrate the distance traveled.<\/p>\n
\n- Back to table of contents<\/a><\/li>\n<\/ul>\n
Vehicle speed sensor<\/strong><\/h4>\nMany vehicle speed sensors of electric speedometers use a magnetic induction element (MRE: Magnetic Resistance Element).<\/p>\n
<\/a>Figure 2: Magnetoresistive element (MRE) speedometer sensor<\/p><\/div>\n
As shown in Fig. 2, this sensor consists of a hybrid IC with a built-in magnetoresistive element and a magnet ring driven by the drive gear (final speed detection) on the output shaft of the transmission.<\/p>\n
<\/a>Figure 3: Properties of a magnetoresistive element (MRE)<\/p><\/div>\n
A magnetoresistive element (MRE) has the property that the magnitude of resistance changes as the magnetic lines of force change with respect to the direction of the current, as shown in Fig. 3.<\/p>\n
<\/a>Figure 4: Vehicle speed sensor structure<\/p><\/div>\n
In addition, since the MRE is arranged around the multipolar magnet ring as shown in FIG. 4, the direction of the magnetic lines of force changes according to the rotation speed of the ring, and a pulse signal is generated.<\/p>\n
This signal is converted to a digital signal by the comparator and transistor in the amplifier and sent to the electronic circuit of the speedometer from the \u2461 terminal of (2) in Fig. 4.<\/p>\n
The output of the vehicle speed sensor is a signal with a period of 4 pulses per rotation of the magnet ring.<\/p>\n
\n- Back to table of contents<\/a><\/li>\n<\/ul>\n
Mechanism of speed display<\/strong><\/h4>\nIn the cross-coil speedometer, when the signal from the vehicle speed sensor is input to the electronic circuit as shown in Fig. 5, this IC counts the pulses of the signal, and the magnitude and direction of the current flowing through the cross-coil according to the vehicle speed. is changed, and the needle (magnet) is swung in the direction of the synthetic magnetic field formed thereby to display the speed.<\/p>\n
<\/a>Figure 5: Cross-coil speedometer configuration<\/p><\/div>\n
\n- Back to table of contents<\/a><\/li>\n<\/ul>\n
Working principle of cross-coil meter<\/strong><\/h4>\n<\/a>Figure 6: Cross-coil meter<\/p><\/div>\n
A cross-coil meter has two coils wound 90 degrees off-set on the outside of a magnetic rotor, as shown in Figure 6.<\/p>\n
As a result, from the electronic circuit, the magnitude and direction of the current flowing through the coils L1 and L2 change like a sinusoidal waveform in conjunction with the vehicle speed. Actually, the graph of the relationship between the current and the vehicle speed is obtained by offsetting the phase of the waveform by 90 degrees as shown in (1) of FIG.<\/p>\n
<\/a>Fig. 7 (1): Relationship between coil current and vehicle speed<\/p><\/div>\n
In the cross-coil type meter, the direction and magnitude of the magnetic field generated by each coil are changed, and the pointer indicates the direction of one magnetic field or a composite magnetic field of two-way magnetic fields as shown in Fig. 7 (2) A to D. That is, it points in the direction of the vector in which the forces are balanced.<\/p>\n
<\/a>Figure 7(2): Pointer direction at each speed<\/p><\/div>\n
\n- Back to table of contents<\/a><\/li>\n<\/ul>\n
Cumulative mileage<\/strong><\/h4>\n<\/a>Figure 8: Pulse motor drive circuit<\/p><\/div>\n
The driving circuit shown in Fig. 8 integrates the signal from the vehicle speed sensor with the rotating pulse motor and odometer to determine the traveled distance.<\/p>\n
<\/a>Figure 1: Electronic speedometer<\/p><\/div>\n
The meter section in Fig. 1 includes a cross-coil speedometer that moves the hands, an electronic circuit that applies current to the cross-coil, and an odometer and trip meter that integrate the distance traveled.<\/p>\n
- \n
- Back to table of contents<\/a><\/li>\n<\/ul>\n
Vehicle speed sensor<\/strong><\/h4>\n
Many vehicle speed sensors of electric speedometers use a magnetic induction element (MRE: Magnetic Resistance Element).<\/p>\n
<\/a>Figure 2: Magnetoresistive element (MRE) speedometer sensor<\/p><\/div>\n
As shown in Fig. 2, this sensor consists of a hybrid IC with a built-in magnetoresistive element and a magnet ring driven by the drive gear (final speed detection) on the output shaft of the transmission.<\/p>\n
<\/a>Figure 3: Properties of a magnetoresistive element (MRE)<\/p><\/div>\n
A magnetoresistive element (MRE) has the property that the magnitude of resistance changes as the magnetic lines of force change with respect to the direction of the current, as shown in Fig. 3.<\/p>\n
<\/a>Figure 4: Vehicle speed sensor structure<\/p><\/div>\n
In addition, since the MRE is arranged around the multipolar magnet ring as shown in FIG. 4, the direction of the magnetic lines of force changes according to the rotation speed of the ring, and a pulse signal is generated.<\/p>\n
This signal is converted to a digital signal by the comparator and transistor in the amplifier and sent to the electronic circuit of the speedometer from the \u2461 terminal of (2) in Fig. 4.<\/p>\n
The output of the vehicle speed sensor is a signal with a period of 4 pulses per rotation of the magnet ring.<\/p>\n
- \n
- Back to table of contents<\/a><\/li>\n<\/ul>\n
Mechanism of speed display<\/strong><\/h4>\n
In the cross-coil speedometer, when the signal from the vehicle speed sensor is input to the electronic circuit as shown in Fig. 5, this IC counts the pulses of the signal, and the magnitude and direction of the current flowing through the cross-coil according to the vehicle speed. is changed, and the needle (magnet) is swung in the direction of the synthetic magnetic field formed thereby to display the speed.<\/p>\n
<\/a>Figure 5: Cross-coil speedometer configuration<\/p><\/div>\n
- \n
- Back to table of contents<\/a><\/li>\n<\/ul>\n
Working principle of cross-coil meter<\/strong><\/h4>\n
<\/a>Figure 6: Cross-coil meter<\/p><\/div>\n
A cross-coil meter has two coils wound 90 degrees off-set on the outside of a magnetic rotor, as shown in Figure 6.<\/p>\n
As a result, from the electronic circuit, the magnitude and direction of the current flowing through the coils L1 and L2 change like a sinusoidal waveform in conjunction with the vehicle speed. Actually, the graph of the relationship between the current and the vehicle speed is obtained by offsetting the phase of the waveform by 90 degrees as shown in (1) of FIG.<\/p>\n
<\/a>Fig. 7 (1): Relationship between coil current and vehicle speed<\/p><\/div>\n
In the cross-coil type meter, the direction and magnitude of the magnetic field generated by each coil are changed, and the pointer indicates the direction of one magnetic field or a composite magnetic field of two-way magnetic fields as shown in Fig. 7 (2) A to D. That is, it points in the direction of the vector in which the forces are balanced.<\/p>\n
<\/a>Figure 7(2): Pointer direction at each speed<\/p><\/div>\n
- \n
- Back to table of contents<\/a><\/li>\n<\/ul>\n
Cumulative mileage<\/strong><\/h4>\n
<\/a>Figure 8: Pulse motor drive circuit<\/p><\/div>\n
The driving circuit shown in Fig. 8 integrates the signal from the vehicle speed sensor with the rotating pulse motor and odometer to determine the traveled distance.<\/p>\n
- Back to table of contents<\/a><\/li>\n<\/ul>\n
- Back to table of contents<\/a><\/li>\n<\/ul>\n
- Back to table of contents<\/a><\/li>\n<\/ul>\n