JPH09281147A - Cross coil type indicating instrument - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a cross coil type indicating instrument which increases the electromagnetic forces of both cross coils to generate a sufficient driving force with a compact structure while maintaining the heat generating amount of temperature compensating resistors in an allowable range by increasing the number of the resistors even if a current limiting resistor is discarded. SOLUTION: Both cross coils 10, 20 are connected in series. Variable resistor for detection 30 and both temperature compensating resistors 40, 50 are connected in series. The common terminal of the coils 10, 20 is connected to that of the resistors 30, 40 via a lead. The resistance values of the resistors 40, 50 are the same as half of the resistance value of the conventional temperature compensating resistor connected in series with the variable resistor 30. The allowable heat dissipating capacities of the resistors 40, 50 are substantially the same as the necessary allowable heat dissipating capacity of the conventional compensating resistor connected in series with the resistor 30.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a cross-coil type indicating instrument.

[0002]

2. Description of the Related Art For example, a cross-coil type fuel meter for a vehicle is constructed by connecting a pair of cross-coils in series so as to cross each other and connecting a variable resistance for detection and a resistance for temperature compensation in series. A bridge circuit is constructed together with the crossing coils.

This fuel meter indicates the remaining amount of fuel according to both electromagnetic forces generated from a pair of cross coils by a current flowing through a bridge circuit according to changes in resistance values of a detection variable resistor and a temperature compensation resistor. indicate.

[0004]

By the way, in this fuel meter, a current limiting resistor is usually connected in series to the bridge circuit in order to prevent an overcurrent from flowing in the bridge circuit. However, this current limiting resistance is a factor that reduces both electromagnetic forces generated by the pair of electromagnetic coils, and thus it is difficult to smoothly display the instruction, which causes a problem.

On the other hand, if the current limiting resistor is abolished in order to increase both electromagnetic forces, the current flowing through the bridge circuit increases abnormally. In this case, although there is no particular problem with the two crossing coils, the power consumption of the temperature compensating resistor exceeds the allowable power consumption thereof due to an abnormal increase in the current flowing through the temperature compensating resistor. As a result, the amount of heat generated by the temperature compensating resistor exceeds the allowable amount of heat radiation, and the temperature compensating resistor may be burnt out due to abnormal heat generation.

On the other hand, when the allowable power consumption of the temperature compensating resistor is increased, the shape of the temperature compensating resistor becomes large.
Therefore, the configuration of the bridge circuit is not compact,
It also causes a high cost. On the other hand, the present inventor considers suppressing the heat generation amount within the allowable range while maintaining the power consumption in the temperature compensation resistor within the allowable range.
We examined the specifications of the temperature compensating resistor used in the fuel meter.

According to this, the temperature compensating resistor is manufactured as an element having various allowable power consumptions, that is, the allowable power consumptions, that is, the allowable heat radiations are fixed. Regardless of the resistance value of the compensation resistor,
It turned out that they were fixed almost the same. In other words, if the number of temperature compensating resistors is increased, even if the resistance value of each temperature compensating resistor is decreased, the allowable heat radiation amount of each temperature compensating resistor is Therefore, it can be said that it is almost the same as the permissible heat radiation amount in the case of one piece.

In view of the above point of view, therefore, the present invention increases the number of temperature compensating resistors even if the current limiting resistors are abolished to increase the heat generation amount of each of the temperature compensating resistors. It is an object of the present invention to provide a cross-coil type indicating instrument in which each electromagnetic force of both cross-coils is increased and a sufficient driving force is exerted under a compact structure while maintaining the allowable range. .

[0009]

In order to achieve the above object, according to the invention described in claims 1 to 4, a plurality of temperature compensating resistors connected in series to the detection variable resistor are connected to each other. It is composed of a temperature compensation resistor. here,
The allowable heat dissipation capacity of each temperature compensating resistor is greater than or equal to the necessary allowable heat dissipation capacity of the temperature compensating resistor.

As a result, although the current flowing through the temperature compensating resistors increases due to the elimination of the current limiting resistors, the amount of heat generated by the current flowing through these temperature compensating resistors does not exceed the allowable heat dissipation capacity. As a result, by using one temperature compensation resistor, which has been one in the past, as a plurality of temperature compensation resistors as described above, even if the current limiting resistor is abolished, the heat generation amount in each element may be abnormal. Instead, it is possible to sufficiently secure the driving force necessary for the smooth indication display of the cross coil type indicating instrument under the increase of the current flowing through both cross coils.

According to the invention of claim 5, the resistance values of the plurality of temperature compensating resistors are substantially the same value, and the total allowable heat radiation capacity of the plurality of temperature compensating resistors is substantially the same. Is greater than the required allowable heat dissipation capacity of the temperature compensating resistor. With this, the same operation and effect as the first aspect can be achieved.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 shows an example in which the present invention is applied to a vehicle cross-coil fuel meter. The fuel meter includes a pair of crossing coils 10 and 20, and the crossing coils 10 and 20 are connected in series with each other. Further, the crossing coil 10 is connected at one end thereof to the positive terminal of the battery Ba via the ignition switch IG of the vehicle, and the other end of the crossing coil 10 is passed through the crossing coil 20 to the vehicle body of the vehicle. It is connected to the chassis ground terminal of.

The cross coils 10 and 20 are wound around the outer surface of a magnet pivotally supported by the pointer shaft so as to cross each other. And these both crossing coils 10 and 20 are
When an electromagnetic force is generated as described below, the above magnet will
A driving force is exerted by the action of a combined vector of these both electromagnetic forces, and the pointer pivotally supported on the pointing shaft is swung. Further, the fuel meter is a variable resistance for detection 30 (hereinafter,
Sender resistor 30) and both temperature compensation resistors 40, 5
0, and the sender resistor 30 and the temperature compensating resistors 40 and 50 are connected in series.

The common terminals of both the crossing coils 10 and 20 and the common terminals of the sender resistor 30 and the temperature compensating resistor 40 are connected by a conductor L. As a result, the crossing coils 10 and 20, the sender resistor 30, and the temperature compensating resistors 40 and 50 form a bridge circuit. Then, when a current flows from the battery Ba to the bridge circuit through the ignition switch IG, the resistance value of the sender resistor 30 and the temperature compensation resistors are connected in a series circuit of the sender resistor 30 and the temperature compensation resistors 40 and 50. An electric current flows according to each resistance change of 40 and 50.

Here, assuming that the resistance values of the crossing coils 10 and 20 are Ra and Rb, respectively, and the sum of the resistance values of the sender resistor 30 and the temperature compensating resistors 40 and 50 is Rs and Rt, respectively. , Ra · Rs = Rb · Rt holds, the potential of the common terminal of both crossing coils 10 and 20 becomes the same as the potential of the common terminal of the sender resistor 30 and the temperature compensating resistor 40, and flows through the conductor L. The current becomes zero. As a result, the bridge circuit is brought into a balanced state.

However, both temperature compensating resistors 40 and 50 are parts having the same specifications, and both temperature compensating resistors 40 and 50 are provided.
Each resistance value of is substantially the same as half the resistance value of the temperature compensating resistance that is conventionally connected in series with the sender resistance 30. This is because the current limiting resistor is eliminated and the current flowing into the bridge circuit is increased to increase the driving force of the magnet.

The permissible power consumption of the temperature compensating resistors 40 and 50, that is, the permissible heat dissipation capacity is determined by the conventional sender resistor 3
It is substantially the same as the required allowable heat dissipation capacity of the temperature compensating resistor connected in series with 0. This means that the amount of heat generated by the temperature compensating resistors 40 and 50 does not exceed the allowable heat dissipation capacity depending on the current flowing in the bridge circuit in the state where the conventional current limiting resistor is abolished. In this case, it goes without saying that the respective heat generation amounts of the cross coils 10, 20 and the sender resistor 30 do not exceed their respective allowable heat dissipation capacities.

The circuit portion surrounded by the broken line in FIG. 1 corresponds to the internal circuit of the fuel meter. Further, the resistance value of the sender resistor 30 changes according to the change in the remaining amount of fuel in the fuel tank of the vehicle, which is the measurement target of the fuel meter. In the present embodiment configured as described above, when the ignition switch IG is turned on, current flows from the battery Ba into the bridge circuit.

In this case, the current flowing through the series circuit of the temperature compensating resistors 40 and 50 and the sender resistor 30 changes the resistance value of the sender resistor 30 and the temperature compensating resistors 40 and 50.
And the resistance values of the crossing coils 10 and 20 change with changes in ambient temperature. When the bridge circuit is in the equilibrium state as described above, the temperature compensation is established.

With this, the indication of the fuel meter can be maintained accurately with temperature compensation. Since the allowable heat dissipation capacities of the temperature compensating resistors 40 and 50 are set as described above, the current flowing through the bridge circuit increases due to the elimination of the current limiting resistor. The amount of heat generated by the current flowing through the resistors 40 and 50 does not exceed the allowable heat dissipation capacity. In this case, since both temperature compensating resistors 40 and 50 have the same specifications, the loads applied to these temperature compensating resistors are equal in power consumption.
Therefore, a good circuit configuration can be provided.

As described above, the conventional temperature compensating resistor is replaced by the two temperature compensating resistors as described above, so that each element forming the bridge circuit can be eliminated even if the current limiting resistor is eliminated. It is possible to increase the current flowing through the two crossing coils 10 and 20 without causing an abnormality in the amount of heat generation in the above, and as a result, it is possible to sufficiently secure the driving force necessary for the smooth indication display of the fuel meter.

By the way, comparing the power consumption by both the temperature compensating resistors 40 and 50 in the present embodiment with the power consumption by one conventional temperature compensating resistor,
The results shown in FIG. 2 were obtained. Here, the curve P1
Shows the relationship between the resistance value and power consumption in the case of one conventional resistance for temperature compensation. A curve P2 shows the relationship between the total resistance value and the total resistance value of the temperature compensating resistors 40 and 50 in the present embodiment.

According to this, it can be seen that the power consumption is reduced when the both temperature compensating resistors 40 and 50 are adopted as in the present embodiment, as compared with the conventional case. FIG. 3 shows a modification of the above embodiment. In this modification, the temperature compensating resistors 40 and 50 described in the above embodiment are
As shown in FIG. 3, they are connected in parallel.

The combined resistance value of the temperature compensating resistors 40 and 50 in this modification is substantially the same as the resistance value of the temperature compensating resistor that is conventionally connected in series with the sender resistor 30. Other configurations are the same as those of the above embodiment.
Thus, according to this modification, the temperature compensating resistor 4 is
The heat generation amounts of 0 and 50 can be suppressed similarly to the case of the temperature compensating resistors 40 and 50 in the above-described embodiment. Therefore, it is possible to achieve the same effects as the above-described embodiment.

In implementing the present invention, the number of temperature compensating resistors is not limited to two, and may be, for example, three or more. In short, it suffices if each calorific value of the total temperature compensation resistor can be suppressed within the allowable limit. Further, in implementing the present invention, the resistance values of the temperature compensating resistors 40 and 50 do not have to be substantially the same as half of the resistance value of the temperature compensating resistor that is conventionally connected in series with the sender resistor 30. Good. Further, the allowable heat dissipation capacities of the temperature compensating resistors 40 and 50 may not be substantially the same as the allowable heat dissipating capacities of the temperature compensating resistors which are conventionally connected in series to the sender resistor 30, and may be larger than this. Good.

Further, in carrying out the present invention, not only the fuel meter but also various cross coil type indicator instruments such as a cross coil type temp meter mounted on a vehicle, an oil pressure meter and a volt meter, or ships and other industrial equipment. The present invention may be applied to a cross coil type indicating instrument for use. Further, in carrying out the present invention, the conducting wire L may be omitted.

[Brief description of drawings]

FIG. 1 is a diagram showing an electric circuit configuration in an embodiment of a vehicle fuel meter according to the present invention.

FIG. 2 is a graph comparing the power consumption of both temperature compensation resistors in the above embodiment with the power consumption of one conventional temperature compensation resistor.

FIG. 3 is an electric circuit diagram showing a modified example of the above embodiment.

[Explanation of symbols]

10, 20 ... Crossing coil, 30 ... Sender resistance, 40, 5
0 ... Resistance for temperature compensation, Ba ... Battery, L ... Conductor wire.

Claims (5)

[Claims] 1. A pair of crossing coils (10, 20) connected in series so as to cross each other, and a detection variable resistor (30) connected in series with each other to form a parallel circuit with the pair of crossing coils. And a temperature compensating resistor, so that an instruction is displayed according to both electromagnetic forces generated from the pair of crossing coils by the current flowing through the parallel circuit according to each resistance value change of the variable resistor and the temperature compensating resistor. In the cross-coil type indicator, the temperature compensating resistor comprises a plurality of temperature compensating resistors (40, 50) connected to each other, and each allowable heat dissipation capacity of the plurality of temperature compensating resistors is the temperature compensating resistor. A cross-coil type indicating instrument characterized by having a required heat dissipation capacity of the resistor for use or more. 2. A pair of crossing coils (10, 20) connected in series so as to cross each other, and a detection variable resistor (30) connected in series with each other to form a bridge circuit together with the pair of crossing coils. And a temperature compensating resistor, for indicating and displaying according to both electromagnetic forces generated from the pair of crossing coils by a current flowing through the bridge circuit according to changes in resistance values of the variable resistor and the temperature compensating resistor. In the crossed coil type indicator, the temperature compensating resistor is composed of a plurality of temperature compensating resistors (40, 50) connected in series to each other, and each allowable heat dissipation capacity of the plurality of temperature compensating resistors is the temperature. A cross-coil type indicating instrument having a compensation resistor having a required allowable heat radiation capacity or more. 3. A pair of crossing coils (10, 20) connected in series so as to cross each other, and a variable resistance for detection (30) connected in series with each other to form a bridge circuit with the pair of crossing coils. And a temperature compensating resistor, for indicating and displaying according to both electromagnetic forces generated from the pair of crossing coils by a current flowing through the bridge circuit according to changes in resistance values of the variable resistor and the temperature compensating resistor. In the crossed coil type indicator, the temperature compensating resistor comprises a plurality of temperature compensating resistors (40, 50) connected in parallel with each other, and each allowable heat dissipation capacity of the plurality of temperature compensating resistors is the temperature. A cross-coil type indicating instrument having a compensation resistor having a required allowable heat radiation capacity or more. 4. The resistance value of each of the plurality of temperature compensating resistors is substantially the same as the resistance value of the temperature compensating resistor divided by the number of temperature compensating resistors. Item 3. The cross-coil type indicating instrument according to Item 2. 5. A pair of crossing coils (10, 20) connected in series so as to cross each other, and a detection variable resistor (30) connected in series with each other to form a bridge circuit together with the pair of crossing coils. And a temperature compensating resistor, so that an instruction is displayed according to both electromagnetic forces generated from the pair of crossing coils by the current flowing through the bridge circuit according to each resistance value change of the variable resistor and the temperature compensating resistor. In the crossed coil type indicator, the temperature compensating resistor comprises a plurality of temperature compensating resistors (40, 50) connected in series with each other, and each resistance value of the plurality of temperature compensating resistors is substantially Cross coil type having the same value, and the total allowable heat dissipation capacity of the plurality of temperature compensating resistors is equal to or more than the necessary allowable heat dissipation capacity of the temperature compensating resistor.示計 device.