JPH0514929U - Cross coil type indicator - Google Patents

Abstract

(57) [Abstract] [Purpose] An object of the present invention is to improve the temperature characteristic of the indication of the cross-coil type indicator by suppressing the fluctuation of the rotational torque having the temperature characteristic of the magnet rotor due to the temperature. [Structure] A pair of coils 4a, 4b wound in a crossed manner
Are driven by duty pulses of constant amplitude whose duty ratios change sinusoidally and cosine respectively according to the measured amount. The measurement amount is instructed by rotating the magnet rotor to which the biasing force is applied in the zero-return direction in the combined magnetic field direction in which the magnetic fields generated by the pair of coils are combined. Further, a temperature sensitive element 10 having a negative temperature resistance characteristic is connected in series with each coil 4a, 4b.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 INDUSTRIAL APPLICABILITY The present invention relates to a cross-coil type indicating instrument, and in particular, a pair of coils wound in an intersecting manner is respectively driven by a duty pulse with a constant amplitude whose duty ratio changes sinusoidally and cosine respectively according to the measurement amount. The present invention relates to a cross-coil type indicator instrument which is driven and rotates a magnet rotor in a direction of a synthetic magnetic field in which magnetic fields generated by a pair of coils are synthesized to indicate a measurement amount.

[0002]

[Prior Art]

 Conventionally, this type of indicating instrument has the configuration shown in FIG. In the figure, reference numeral 1 denotes a travel sensor that generates one travel pulse signal each time the vehicle travels a predetermined distance according to the travel of the vehicle. The frequency of the travel pulse signal increases according to the vehicle speed and The period decreases according to the vehicle speed. Reference numeral 2 denotes a micro computer (CPU) that operates according to a predetermined program, and when the traveling pulse signal from the traveling sensor 1 is input, the time from the previous traveling pulse signal is timed every rise or fall thereof. Alternatively, the traveling speed of the vehicle is measured by counting the number of traveling pulse signals per unit time.

The CPU 2 measuring the traveling speed of the vehicle uses sin duty data in which the duty ratio changes sinusoidally (sin) and cos duty in which the duty ratio changes cosine (cos) according to the measured traveling speed. And the data and supplies them to the sin duty pulse generator 3a and the cos duty pulse generator 3b, respectively. The sin duty pulse generator 3a generates a pulse having a duty ratio designated by this data based on the sin duty data applied to its input. On the other hand, the cos duty pulse generator 3b generates a pulse having a duty ratio specified by this data based on the cos duty data applied to its input.

The pulse signals generated by the sin duty pulse generator 3a and the cos duty pulse generator 3b are supplied to drive circuits 5a and 5b provided corresponding to the pair of coils 4a and 4b of the cross-coil movement 4, respectively. The driving circuits 5a and 5b drive the corresponding coils 4a and 4b, respectively. The pair of coils 4a and 4b generate crossing magnetic fields when driven, and rotate a magnet rotor (not shown) rotatably arranged in a space formed by these coils in a direction of a synthetic magnetic field that is a combination of the crossing magnetic fields. By the rotation of the magnet rotor, the pointer 4c fixed to the rotating shaft is rotated to an angular position corresponding to the measured amount.

A constant voltage is supplied from the constant voltage circuit 6 to the drive circuits 5a and 5b, and the peak value of the voltage supplied to the pair of coils 4a and 4b via the drive circuits 5a and 5b is kept constant. It is supposed to be done.

Further, the drive circuits 5a and 5b are specifically configured as shown in FIG. 5, and include transistors TR1 and TR2 connected in series between the output of the constant voltage circuit 6 and the ground, respectively. The transistors TR3 and TR4 are provided, and the coils 4a and 4b of the cross-coil movement 4 are respectively connected between the interconnection point of the transistors TR1 and TR2 and the interconnection point of the transistors TR3 and TR4.

To the bases of the transistors TR1 to TR4, the duty pulse signals from the duty pulse generators 3a and 3b are selectively applied by the combination of the transistors TR1 and TR4 and the transistors TR2 and TR3 to turn on one of them. As a result, an average current corresponding to the duty ratio is passed through the coils 4a and 4b in the directions indicated by the solid and dotted lines.

In addition, in order to return the pointer 4c to the 0 instruction position when the ignition switch is turned off and the power supply is stopped, the rotating shaft of the magnet rotor is constantly biased in the direction of zero by a mustache full-spring. Since it is provided, a method such as correcting the duty ratio of the duty pulse signal that drives the coils 4a and 4b in accordance with the measured amount is usually used to prevent an instruction error due to this biasing force. It is being done.

[0009]

[Problems to be solved by the device]

 However, when the ambient temperature rises and the resistance values of the coils 4a and 4b increase, or the magnetic flux of the magnet rotor decreases, an error in the minus direction of the pointer 4c occurs.

Incidentally, the rotational torque T generated in the magnet rotor by passing a current through the coils 4a and 4b is determined by T = α · N · I · A.

Here, N is the number of turns of the coil, I is the current flowing in the coil, A is the magnetic flux of the magnet rotor, and N is a constant, but I has a positive temperature coefficient shown in FIG. Depending on the resistance values of the coils 4a and 4b, the magnetic flux of the magnet rotor decreases at a rate of -0.4% / ° C, and the magnetic flux of the magnet rotor decreases at a rate of -0.19% / ° C as shown in Fig. 7. T has a negative temperature coefficient, and becomes smaller as the ambient temperature rises.

Therefore, in relation to the urging force of the beard total dance spring described above, when the ambient temperature is higher than room temperature, the indicated value of the pointer 4c shows an error in the negative direction as shown in FIG. However, there was a problem that the error of (3) occurs.

Therefore, in view of the above-mentioned conventional problems, the present invention provides a cross-coil type indicating instrument in which the temperature characteristic of the magnet rotor is suppressed from varying with temperature due to the temperature variation and the temperature characteristic of the instruction is improved. It is an issue.

[0014]

[Means for Solving the Problems]

 In order to solve the above-mentioned problems, a cross-coil type indicator made by the present invention has a pair of coils wound alternately and having a constant amplitude whose duty ratio changes sinusoidally and cosine respectively according to the measured amount. Each of them is driven by a duty pulse, and the measured amount is indicated by rotating the magnet rotor, which is biased in the zero-return direction, in the combined magnetic field direction that combines the magnetic fields generated by the pair of coils. The cross-coil type indicator is characterized in that a temperature-sensitive element having a negative temperature resistance characteristic is connected in series with each coil.

[0015]

[Action]

 In the above configuration, the temperature-sensitive element that has a negative temperature resistance characteristic connected in series with each coil has a smaller resistance value as the temperature rises, lowering the combined resistance value with the coil. The increase in the coil resistance and the decrease in the magnetic flux of the magnet rotor cause the decrease in the rotational torque.

[0016]

【Example】

 Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a circuit diagram showing drive circuits 5a and 5b applied to a cross-coil type indicating instrument according to the present invention. In FIG. 1, parts corresponding to the conventional ones described above with reference to FIGS. The same reference numerals are given and detailed description thereof is omitted.

In FIG. 1, one of the cross-coil movements is provided between the connection points of the transistors TR1 and TR2 and the transistors TR3 and TR4 which are connected in series between a constant voltage circuit (not shown) and ground. A series circuit of the coils 4a and 4b and a temperature sensitive element 10 having a negative temperature resistance characteristic such as a thermistor is connected.

Due to the negative temperature resistance characteristic of the temperature sensitive element 10, the resistance value thereof decreases as the temperature rises, as shown in FIG. Therefore, by changing the resistance value of the temperature sensitive element 10 not only to increase the resistance values of the coils 4a and 4b due to the temperature rise but also to compensate for the decrease of the rotational torque due to the decrease of the magnetic flux of the magnet rotor. Therefore, the rotating torque does not change according to the temperature change, and a cross-coil type indicating instrument can be obtained in which the indication of the pointer is not affected by the temperature.

When there is no resistance component consisting of the temperature sensitive element 10 connected in series with the coil 4, the coil driving waveform is generated by the back electromotive force generated in the coils 4a and 4b when the duty pulse signal is applied. The spike-shaped voltage indicated by the dotted circle in Fig. 3 (a) was superimposed on the rising and falling edges of the coil, which affected the linearity indicated by the pointer. As shown in Fig. 3 (b), the spike-like voltage due to the back electromotive force is attenuated by the resistance component of the temperature-sensitive element 10 connected in series with the temperature sensing element 10. Will also be moderated.

In the above description, only the temperature sensitive element 10 is connected in series with the coil 4, but the resistance 11 is connected in parallel with the temperature sensitive element 10 as shown by the dotted line, and the resistance 1 By setting the resistance value of 1 to various values, the temperature resistance characteristic of the temperature sensitive element 10 can be adjusted to a desired one.

[0021]

[Effect of the device]

 As described above, according to the present invention, the increase of the resistance value of the coil caused by the temperature rise and the decrease of the rotation torque of the magnet rotor due to the decrease of the magnetic flux of the magnet rotor are compensated. The temperature characteristic of the instruction can be improved by suppressing the fluctuation of the torque due to the temperature.

[Brief description of drawings]

FIG. 1 is a view showing an embodiment of a main part of a cross coil type indicator according to the present invention.

FIG. 2 is a graph showing temperature resistance characteristics of the temperature sensitive element in FIG.

FIG. 3 is a waveform diagram for explaining an effect obtained by the configuration of FIG.

FIG. 4 is a diagram showing a general configuration of a cross coil type indicating instrument according to the present invention.

FIG. 5 is a view showing a main part of a conventional cross coil type indicating instrument.

FIG. 6 is a graph showing a temperature resistance characteristic of a coil.

FIG. 7 is a graph showing temperature magnetic flux characteristics of a magnet rotor.

FIG. 8 is a graph showing a temperature indicating characteristic of a conventional cross coil type indicating instrument.

[Explanation of symbols]

 4a, 4b coil 10 temperature sensitive element

Claims (1)

[Scope of utility model registration request] 1. A pair of coils wound in an intersecting manner are respectively driven by a duty pulse having a constant amplitude whose duty ratio changes sinusoidally and cosine respectively according to the measured amount, and the pair of coils are generated respectively. In a cross-coil type indicating instrument configured to rotate the magnet rotor to which a biasing force is applied in the zero-return direction in the combined magnetic field direction in which the magnetic fields are combined, and to indicate the measurement amount, A cross-coil type indicator having a temperature-sensitive element having a temperature resistance characteristic connected thereto.