JPH0480662A - Cross coil type indicator - Google Patents

Abstract

PURPOSE:To achieve stability of an indication characteristic of a pointer regardless of changes in atmospheric temperature by connecting a series circuit of a Zener diode and a resistance element to a connection point between parts of two coils each and a connection point between a resistance and a sensor. CONSTITUTION:Resistance values are determined within a variable range of a sensor R2 to meet the requirement of R1.RA = R2.RB. When a change in the sensor R2 is so limited that a potential difference between points A and C does not exceed a forward drop voltage of a Zener diode Z, an inflow and outflow of a current at a point A is I1 only and I1 = I3 is given. The sensor R2 further changes and as the potential difference between points A and B exceeds the forward drop voltage of the diode Z, the current flows from the point A to B or reversely through the diode Z and a resistance R3 and an angle of deflection of a pointer shifts with I1 not equal to I3. A change (negative linear characteristic) in an internal resistance R2 is corrected by the resistance R3 having a positive linear characteristic due to an atmospheric temperature of the diode Z to reduce a total change in resistance value thus resulting in little change in indication as caused by the atmospheric temperature.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a crossed coil type indicator, and more particularly to a crossed coil type indicator that accurately indicates the indication of a thermometer for a vehicle.

[Prior Art] Conventionally, thermometers for vehicles have been used as water temperature gauges, and as shown in Japanese Utility Model Publication No. 58-17258, they are equipped with, for example, a Zener diode, and have an insensitive area (intermediate stable area) in a normal range for water temperature. The instrument's indication, that is, the angle of deflection of the pointer, is kept constant when the water temperature changes, which does not pose a problem in use, so that the user does not feel uneasy, and when the temperature reaches a point that causes a problem in use, the indicator immediately changes to red. It is configured to indicate the zone (dangerous area) and notify the user of danger. In other words, the deflection angle of the pointer with respect to changes in water temperature exhibits characteristics as shown by the solid line in FIG.

[Problem to be solved by the invention]

The water thermometer described above is particularly required to accurately indicate the red zone, which alerts the user to danger, and for example, indicates the red zone when the water temperature rises to 120°C.

However, in recent years, there has been a trend to downsize water thermometers, and as the circuit elements are crowded together, the ambient temperature becomes high, and the temperature of the Zener diode, which indicates the above-mentioned indicating characteristics of the water thermometer, rises. As a result, the internal resistance of the Zener diode changes, and the indicating characteristics of the water temperature gauge change as shown by the broken line in FIG. 3, causing a problem that the red zone is indicated before the water temperature rises to 120°C.

Therefore, in the cross-coil type indicator of the present invention, it is an object to obtain stable indicator characteristics regardless of changes in ambient temperature.

[Means for Solving the Problems] In order to achieve the above object, the crossed coil type indicating instrument of the present invention has two sets of coil portions wound in a crossed manner and connected in series with each other, and these two sets of coil portions. A permanent magnet provided to be rotated by the resultant magnetomotive force of a series circuit with the sensor, a Zener diode whose anode side is connected to the first connection point of the two sets of coil parts, and whose cathode side is connected to the second connection point between the resistor and the sensor, and a positive temperature characteristic. This is a cross-coil type indicating instrument characterized by comprising a series circuit with a resistive element having a resistance element.

Also, instead of the Zener diode, a normal first
A diode may be provided, and a second diode may be configured such that its cathode side is connected to a first connection point between the two sets of coil parts, and its anode side is connected to a second connection point between the resistor and the sensor. .

[Effect]

With the above configuration, the combined resistance of the internal resistance of the Zener diode and the element having positive resistance characteristics is approximately constant.

Furthermore, when a forward current flows through the second diode, the combined resistance of the internal resistance of the first diode and the element having positive resistance characteristics is approximately constant.

〔Effect of the invention〕

As described above, since changes in the internal resistance of the Zener diode or the first diode due to changes in ambient temperature are corrected, stable indication characteristics can be obtained regardless of changes in ambient temperature, and red zone indications can be maintained. This has the advantage that it can be done accurately.

〔Example〕

DESCRIPTION OF THE PREFERRED EMBODIMENTS Examples of the cross-coil type indicator according to the present invention will be described below with reference to the drawings.

Figures 1 and 2 show the configuration of the instrument of the present invention, which includes a two-pole permanent magnet 4 with a pointer shaft 2 located inside a housing 1, a four-element coil T wound around the outer circumference of the housing 1, and -
It consists of T4. Among these coils, T = ,
T3 is wound in a parallel direction, and a coil Tz is wound in a direction perpendicular to this coil T,,T,.

The coil I4 is wound in parallel to each other, and the coils T and I3 are wound in opposite directions. These four coils T1 to T4 are connected to a fixed resistor R2 and a sensor R2 as shown in FIG.

However, each coil T, , T, , T is set so that the field vectors produced by T1 and I3 are in opposite directions, and the field vectors produced by coils T2 and I4 are also in opposite directions.
3. T.

is wired. Furthermore, a series circuit of a Zener diode Z2 and a resistor R2 is inserted between points A and B, and each resistance value R, , R, , R is set within the variable range of the sensor R2.
The resistance values R, RA, and R1 are determined so that the following equation (1) holds between A and R. Then, the series combined resistance value RA of coils T + and T z is set as coil T3. If the series combined resistance value of T, is R3, and the total current flowing from the power supply Ba is Io, then the coil T.

The current flowing through is ■.

The current I3 flowing through the coils T, , T2 is as follows. Here, each coil T, , T2 . Since the bipolar magnetized permanent magnet 4 in FIG. 1(b) directs its magnetic pole in the direction of the field vector created by T, , T, the deflection angle θ of the pointer 3 in FIG. It can be obtained with (Here, N, , N, , N, , N are the number of turns of the coils T, , T, , T3.T, respectively.) Based on the principle described above, in the circuit shown in Fig. 2, the resistance of sensor R2 is If the value changes, the deflection angle θ of the pointer 3 also changes accordingly.

Here, the equation (1) R1・RA−Rz・R3 holds true, which means that R+, Rz, RA, R*
This means that the bridge circuit consisting of four resistors is balanced. Therefore, in the circuit shown in Figure 1, the potential difference between A and B is "
0, and no current other than I flows into or out of point A, so I+=Ii.

Therefore, the deflection angle θ of the pointer 3 in Fig. 1 a and b is as follows.
T1・I2. It is uniquely determined by the number of turns of each coil T, ,T,.

Then, when R2 changes, the equation R1・RA=R2R8 no longer holds, and a potential difference occurs between A and C, but R2
If the change in is small and the potential difference between A and C does not exceed the forward drop voltage of Zener diode Z, only 11 currents will flow in and out of □ to point A, and the relationship I+ = Is will hold.
Therefore, the deflection angle θ of the pointer 3 does not change from the angle given by equation (5).

When R2 changes further and the potential difference between A and B becomes larger than the forward drop voltage of Zener diode Z, current flows from point A to point B or in the opposite direction through Zener diode Z and resistor R1. flows, so 11≠
13, and the pointer deflection angle θ deviates from equation (5).

If sensor R2 has a resistance value smaller than the value that satisfies equation (1), and the potential difference between A and C is
If the forward voltage drop exceeds I1,
A part of the current flows to the sensor R2 which passes through the Zener diode Z and the resistor R3.

>1. Therefore, the deflection angle θ of the pointer 3 becomes large.

On the other hand, if sensor R2 takes a sufficiently large value and the potential difference between A and C exceeds the reverse voltage of Zener diode Z, a part of I2 passes through resistor R3 and Zener diode Z to the coil section. T,, flows to T2, so 1
．． <■, and the deflection angle θ becomes smaller.

As can be seen from the above description, the characteristics shown in FIG. 3 can be obtained by the circuit shown in FIG. 2. In Fig. 3, the point ■ on the water temperature axis is the point where equation (1) holds true, and the point between point ■ and point 0 is where the A-crjIt level difference is smaller than the forward voltage drop of the Zener diode Z, and rl = I3. This is the range in which this is true.

Therefore, when indicating the red zone, a forward current flows through the Zener diode Z. Since the conventional type does not have a resistor R3, the internal resistance of the Zener diode changes depending on the ambient temperature, resulting in 1',...
I3 changes (when the ambient temperature is high, ■1 large, I3 small,
(The deflection angle θ of the pointer 3 becomes large). On the other hand, in the instrument of the present invention, as shown in Fig. 4, the change in internal resistance R2 (negative linear characteristic) is corrected by the resistor R3 having positive linear characteristic depending on the ambient temperature of the Zener diode Z, and the total resistance value It makes the changes smaller. As a result, it is possible to create a thermometer that hardly changes its reading due to ambient temperature.

In the first embodiment shown in FIG. 2, a Zener diode is connected between A and B, but as shown in FIG. A parallel circuit of second diodes D, D2 can be inserted and used. In this circuit configuration, when the water temperature is low (~■), a forward current flows through the second diode D2, and when the water temperature is high (after ■), a forward current flows through the first diode D1. Therefore, in order to accurately indicate the red zone regardless of changes in ambient temperature, a resistor R3 that corrects the temperature characteristics of the first diode D1 is connected in series only to the first diode D1.

As described above, in the instrument of the present invention, the indicating characteristics of the pointer 3 can be stabilized, and the red zone can be indicated accurately.

[BRIEF DESCRIPTION OF THE DRAWINGS] FIGS. 1(a) and 1(b) are a plan view and a vertical cross-sectional view schematically showing the structure of a cross-coil indicating instrument of the present invention, and FIG. 2 is a first embodiment of the instrument of the present invention. An electric circuit diagram showing an example, Fig. 3 is a deflection angle characteristic diagram when using the circuit shown in Fig. 2, and Fig. 4 is a characteristic diagram showing the combined resistance value of internal resistance R2 and resistor R3 of Zener diode Z with respect to temperature. , FIG. 5 is an electrical circuit diagram showing a second embodiment of the meter of the present invention. 2... Pointer shaft, 3... Pointer, 4... 2-pole permanent magnet T, , T,... Coil T forming the coil part of the bow set.
,,T,...Coil constituting another set of coil parts, RI...Resistor, Rz...Sensor, R3...Resistor with positive linear resistance characteristics, Z...Zener diode , D, , D2... 1st. Second diode.

Claims (2)

[Claims] (1) Two sets of coil parts that are wound in a crossed manner and connected to each other in series, a permanent magnet provided to rotate by the composite magnetomotive force of these two sets of coil parts, and fixed at the center of this permanent magnet. A pointer shaft fixed to the pointer shaft, a series circuit of a resistor and a sensor connected in parallel to the two sets of coil parts, and an anode connected to the first connection point (A) of the two sets of coil parts. ) is characterized by comprising a series circuit of a Zener diode whose cathode side is connected to the second connection point (B) between the resistor and the sensor, and a resistance element having positive temperature characteristics. Cross-coil indicator. (2) Two sets of coil parts that are wound in a crossed manner and connected to each other in series, a permanent magnet provided to be rotated by the composite magnetomotive force of these two sets of coil parts, and fixed at the center of this permanent magnet. a pointer shaft fixed to the pointer shaft, a series circuit of a resistor and a sensor connected in parallel to the two sets of coil parts, and the anode side connected to the first connection point (A) of the two sets of coil parts. )
a series circuit of a first diode whose cathode side is connected to the second connection point (B) between the resistor and the sensor, and a resistance element having positive temperature characteristics, and a series circuit whose cathode side is connected to the second connection point (B) between the resistor and the sensor; A cross-coil type pointer meter comprising a second diode whose anode side is connected to the connection point of the resistor and the sensor, respectively, at the connection point of the coil portion.