JPH07318434A - Composite sensor - Google Patents

Abstract

PURPOSE:To restrain a measurement error within an allowable range ' by restraining one thermistor incorporated into the same case from thermally interfering with a mating thermistor due to self-heating by reducing a quantity of heat of a heat conductive passage. CONSTITUTION:A composite sensor is composed of a first thermistor 1, a second thermistor 5, a case 4, a connector part 7 and a heat dissipating part 12. The heat dissipating part 12 has an external heat conductive passage, and conduction expands the surface area of the case 4 being the heat conductive passage reaching the thermistor 5 from the thermistor 1, and enhances a heat dissipating rate. In this way, when a quantity of heat of the heat conductive passage reaching the second thermistor 5 from the first thermistor 1 is reduced, thermal influence with the thermistor 5 by self-heating of the thermistor 1 can be restrained, and a temperature except a liquid temperature can be prevented from being detected, and the liquid temperature can be accurately measured.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a composite sensor suitable for detecting a liquid temperature in, for example, an automobile engine cooling system.

[0002]

2. Description of the Related Art For example, an automobile is equipped with an engine cooling system in which cooling water is sent into an engine room to cool the engine, the cooling water is sent into a radiator to be cooled, and then circulated again in the engine room.

Then, the water temperature in the radiator is measured by a temperature sensor, the cooling fan motor is controlled based on the measured value, while the water temperature in the engine room is measured by the temperature sensor, and the engine is measured based on the measured value. The fuel injection, ignition timing, idle speed, etc. are controlled.

Conventionally, the above-mentioned two types of sensors use thermistors having different characteristics. However, these thermistors are integrally incorporated in one case in order to save space. An example of the above-mentioned temperature sensor is shown in FIG. In the temperature sensor described above, the ring-shaped first
The thermistor 1 is pressed against the support seat 6 of the case 4 via the electrode plate 3 by the spring 2, and the second thermistor 5
Has penetrated through the through hole 1a of the first thermistor 1 and has been fixed to the front end of the case.

[0005]

By the way, the second thermistor 5 detects the temperature of the engine coolant quickly and sends the detection signal to the controller as an engine control unit to control the temperature of the engine coolant. It is used as a sensor.

Further, the first thermistor 1 detects the temperature of the engine coolant as in the case of the second thermistor 5 and sends the detection signal to the meter display system so that the temperature of the engine coolant is normal to the driver. It is used as a sensor to indicate whether it is abnormal or abnormal. In current automobiles, the number of items displayed on the dashboard is increasing, so it is necessary to appropriately match the degree of temperature change with the degree of change of the meter needle. ), It is required to secure a large current variation range. Therefore, with respect to the first thermistor 1, the degree of self-heating is changed depending on the temperature, and the current change width that follows the temperature change under a constant voltage is increased.

First thermistor 1 and second thermistor 5
Means that the thermistors 1 and 5 are assembled in the same case 4, the required characteristics of the thermistors 1 and 5 are different, and the first thermistor 1 self-heats.
Thermal interference occurs between the thermistors 1 and 5.

Specifically, when the first thermistor 1 self-heats, the heat is transferred to the second thermistor 5, which is the other party, and the second thermistor 5 receives thermal interference from the first thermistor 1. As a result, a temperature other than the liquid temperature of the engine cooling liquid is also detected, and there is a problem in that an error occurs in the liquid temperature measurement of the engine cooling liquid. An experiment was conducted using the temperature sensor shown in FIG. When a voltage of 14 V is applied to the first thermistor 1 via the series resistance 51 Ω at the sensor ambient temperature of 110 ° C. to cause self-heating, the influence of the heat on the second thermistor 5 is: There was an error of -4% in the resistance value ratio and 1.6 to 1.8 ° C in the temperature difference. This value exceeds the allowable range of the engine control error value.

An object of the present invention is to prevent the thermal interference of one thermistor incorporated in the same case by itself to cause thermal interference with the other thermistor as much as possible, and to suppress the measurement error within an allowable range. To provide a sensor.

[0010]

In order to solve the above-mentioned problems, a composite sensor according to the present invention comprises a first thermistor and a second thermistor, a case, a connector portion, and a heat dissipation portion. The first thermistor and the second thermistor have different characteristics and measure temperature, and the first thermistor is formed in a ring shape having a through hole in the central portion. And the case is a hollow container having a support seat and a storage portion, and the support seat supports the first thermistor and holds the thermistor at a position within the case retracted from the tip of the case,
The accommodating portion is provided at a position projecting from the support seat to the tip side of the case, and accommodates and holds the second thermistor in a position different from that of the first thermistor, and the connector portion is the case. Of the first thermistor attached to the case supporting seat and fixing the second thermistor in the case housing while closing the opening of the first thermistor. The electrode plate is attached to the end surface of the first thermistor, and the spring presses the first thermistor to the case support seat via the electrode plate and electrically connects to the electrode plate. The heat dissipating section reduces the amount of heat in the heat conduction path from the first thermistor to the second thermistor, so that the self-dissipation of the first thermistor is reduced. It is intended to suppress the thermal interference to the second thermistor by heat.

Further, the heat dissipating portion has an outer heat conducting path, and the outer heat conducting path is a surface area of a case forming a heat conducting path from the first thermistor to the second thermistor. To increase the heat dissipation rate.

Also, in the composite sensor having an inner heat conduction path, the inner heat conduction path passes through at least a lead wire passing through a through hole of the first thermistor and reaches the second thermistor. The amount of heat conducted to the thermistor No. 2 is reduced.

Further, in the composite sensor having a heat radiation path, the heat radiation path has an increased amount of heat conducted to the connector portion side through the electrode plate and the spring.

Further, in the composite sensor having an inner heat conducting path and a heat radiating path in addition to the outer heat conducting path, the inner heat conducting path passes through the through hole of the first thermistor. The amount of heat conducted to the second thermistor through at least the lead wire leading to the second thermistor is reduced, and the heat radiation path conducts heat to the connector portion side through the electrode plate and the spring. It is a heightened one.

[0015]

Under a constant voltage, if the resistance of the thermistor decreases, that is, if the temperature rises, the current flowing through the thermistor increases, and the amount of heat generated increases in proportion to the power. In other words, the higher the external temperature, the larger the amount of heat generated, and the larger the amount of heat interference with the second thermistor 5 due to the self-heating of the first thermistor 1. The result is shown in FIG. Further, FIG. 9 shows the temperature distribution of the case in the conventional temperature sensor. The measurement point a shown in FIG. 9 is
The measurement point B is a part of the case 4 that is heated by self-heating of the first thermistor 1, and the measurement point B is a part of the case 4 that is provided with a support seat 6 that supports the first thermistor 1.
The measurement point C is the side portion of the case 4 in which the second thermistor 5 is housed, and the measurement point D is the case tip portion in which the second thermistor 5 is provided, as shown in FIG. The temperature at the measurement point b is
It was found that the temperature was higher than that of C and D. Based on this result, measures were taken to suppress the effect of thermal interference between the two thermistors. Hereinafter, measures against thermal interference in the present invention will be described.

As a result of various studies, the inventor of the present invention has shown that, when one of the thermistors 1 self-heats as shown in FIG. 5, the heat transfer path to the other thermistor 5 is through the case 4 to the other thermistor 5. The A route to reach and the other side of the thermistor 5 that penetrates the through hole 1a of the thermistor 1
It was found that there is a B route reaching at least through the lead wire 5a. Further, the heat generated by the thermistor 1 is transmitted through the electrode plate 3 and the spring 2 to the connector portion 7
We found that there is a C route that radiates heat on the side.

According to the present invention, the heat quantity of the heat conduction path from the first thermistor 1 to the second thermistor 5 is reduced, so that the self-heating of the first thermistor 1 causes the heat interference to the second thermistor 5. The basic principle is to deter.

The first countermeasure against heat interference is to increase the surface area of the case 4 forming the heat conduction path from the first thermistor 1 to the second thermistor 5 to increase the heat dissipation rate.
The result is shown in FIG. As is apparent from FIG. 6, the temperature rise at the measuring point B is 1.6 deg due to the first measure against thermal interference.
Drops to 0.9 deg, and the temperature rises at the measurement point d.
Since 0 deg dropped to 0.3 deg, it was found that the first countermeasure against thermal interference is effective.

The second countermeasure against thermal interference is to reduce the amount of heat conducted to the second thermistor 5 through at least the lead wire 5a that penetrates the through hole 1a of the first thermistor 1 and reaches the second thermistor 5. It is a thing. In the case of this measure, the temperature rise of the second thermistor 5 was suppressed by 0.3 deg at the sensor ambient temperature of 110 ° C.

Further, in order to reduce the heat transfer amount of the A route and the B route, the heat influence of the thermistor 5 can be reduced by increasing the heat dissipation of the thermistor 1 in the C route direction. Therefore, the third countermeasure against thermal interference is to use the electrode plate 3
Also, the amount of heat conducted to the connector portion 6 side through the spring 2 is increased. In the case of this countermeasure, the temperature rise of the second thermistor 5 is 0.4 at the sensor ambient temperature of 110 ° C.
deg was suppressed.

[0021]

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

FIG. 1 is a sectional view showing an embodiment of the present invention. In the figure, the present invention has a first thermistor 1 and a second thermistor 5, a case 4, a connector portion 7, and a heat dissipation portion 12.

The first thermistor 1 and the second thermistor 5 have different characteristics and measure temperature.
The first thermistor 1 is formed in a ring shape having a through hole 1a in the central portion.

The case 4 is a metal hollow container having a large diameter portion 4a and a small diameter portion 4b. Large diameter part 4a and small diameter part 4
"b" is a coaxially connected one, and the small diameter portion 4b
Is a hollow structure with a bottom that is reduced in diameter from the large-diameter portion 4a,
The large diameter portion 4a has a hollow structure having an opening into which the connector portion 7 is inserted, and a support seat 6 is formed between the large diameter portion 4a and the small diameter portion 4b.

The support seat 6 supports the first thermistor 1 and holds the thermistor 1 at a position within the case 4 retracted from the tip of the case. The storage portion 8 is provided in the case small-diameter portion 4b protruding from the support seat 6 toward the front end side of the case, and stores and holds the second thermistor 5 at a position in the case different from that of the first thermistor 1.

The connector portion 7 is integrally molded of resin including the second thermistor 5 and its lead wires 5a, 5a, and the resin molded body covering the outer periphery of the second thermistor 5 and its lead wires 5a, 5a. 4c has a reduced diameter, closes the opening of the large-diameter portion 4a of the case, and connects the second thermistor 5 to the through hole 1 of the first thermistor 1 on the support seat 6.
The thermistor connection terminals 9a and 9b, the electrode plate 3, and the spring 2 are provided so as to be housed and held in the housing portion 8 of the case 4 different from the first thermistor 1 through the a. The lead wires 5a, 5a of the thermistor 5 are
Insulated.

The thermistor connecting terminal 9a has a spring seat 10, and the spring seat 10 is a first seat on the case support seat 6.
Is provided on the end face facing the thermistor 1.

The electrode plate 3 is attached to the end face of the first thermistor 1, and the spring 2 presses the first thermistor 1 to the case support seat 6 via the electrode plate 3 and at the same time, the electrode plate 3 And is electrically connected to the spring seat 10. In the thermistor connection terminal 9b,
Lead wires 5a, 5a of the thermistor 5 are connected.

The sleeve 11 is a hollow body which is integrally molded with the connector portion 7 by resin molding and is covered. The spring seat 10, the electrode plate 3 and the spring 2 are received inside from the opening at the tip end thereof, and the case 4 and the case 4. The sleeve 11 that electrically insulates between the
The container 4 functions as a container for accommodating a medium (for example, silicone oil) 13 that is filled in the case 4 and dissipates heat from the thermistor during assembly.

Further, the connector portion 7 has a protruding claw 7a,
The protruding claw 7a is provided in an annular shape so as to project to the side of the connector portion 7, the case 4 has a fixed claw 4c, and the fixed claw 4c extends along the opening edge of the case large-diameter portion 4a. The fixing claw 4c is bent inward to be engaged with the projecting claw 7a, so that the connector portion 7 is attached to the case 4
It is designed to be fixed inside. P is a packing for hermetic sealing.

The heat dissipation section 12 is a heat conduction path (route A or B) from the first thermistor 1 to the second thermistor 5.
By reducing the amount of heat of the (root), thermal interference with the second thermist 5 due to self-heating of the first thermistor 1 is suppressed.

The heat dissipating portion 12 according to the first embodiment has an outer heat conduction path (route A), and the outer heat conduction path heats from the first thermistor 1 to the second thermistor 5. The surface area of the case 4 forming the conduction path is enlarged to increase the heat dissipation rate. The materialized heat dissipation part 1 shown in FIG.
Reference numeral 2 denotes fins 12a provided at regular intervals in a range from a portion of the case 4 provided with the support seat 6 (a portion corresponding to the measurement point B shown in FIG. 9) to the case small diameter portion 4b. In this case, as shown in FIG. 6, the temperature rise at the measurement point B is reduced by 50%, and the temperature rise at the measurement point D is 70%.
It was confirmed as a result of the experiment that it decreased.

The heat dissipation part 12 according to the first embodiment is
The surface area of the case 4 may be increased by increasing the distance L between the thermistor 1 and the thermistor 5 (see FIG. 5). Further, the heat dissipation part 12 shown in the above-mentioned embodiment
2 is a portion of the case 4 in which a recess 14 is formed between the case small diameter portion 4b and the case large diameter portion 4a, and in particular, the support seat 6 is provided (measurement point shown in FIG. 9). The surface area of the case 4 in the range from the portion corresponding to (b) to the case small diameter portion 4b is enlarged.

The heat dissipating portion 12 according to the second embodiment has an inner heat conduction path (B route), and the inner heat conduction path (B route) passes through the through hole 1a of the first thermistor 1. At least the lead wire 5 penetrating to the second thermistor 5
The amount of heat conducted to the second thermistor 5 through a and 5a is reduced. When the lead wires 5a, 5a are molded in the resin molded body 4c integrally molded with the connector portion 7, the second thermistor 5 is provided via the resin molded body 4c in addition to the lead wires 5a, 5a. It reduces the amount of heat transferred to.

The heat dissipating portion 12 of the second embodiment shown in FIG.
Is set to a large gap δ between the inner diameter portion of the first thermistor 1 (opening edge of the through hole 1a) and the resin molded body 4c covering the lead wire 5a. 4c to reduce the amount of heat transferred to the second thermistor 5 through the resin molded body 4c that passes through the through hole 1a of the first thermistor 1 and reaches the second thermistor 5. is there. In this case, when the lead wire 5a is not covered with the resin molding 4c, the amount of heat transferred from the first thermistor 1 to the lead wire 5a may be reduced.

In the heat dissipating portion 12 of the second embodiment shown in FIG. 5, the distance L between the first thermistor 1 and the second thermistor 5 is increased, or the lead wire 5a is made of, for example, Cu-Ni wire. The amount of heat conducted to the second thermistor 5 through the lead wires 5a, 5a may be reduced by using such a material having a low thermal conductivity.

The heat dissipating portion 12 of the second embodiment shown in FIG.
Includes a spacer 15 for blocking heat between the inner diameter portion of the first thermistor 1 (opening edge of the through hole 1a) and the resin molded body 4c covering the lead wire 5a. From the resin molded body 4c to the second thermistor 5 through the through hole 1a of the first thermistor 1 to reach the second thermistor 5. It lowers. In this case, when the lead wire 5a is not covered with the resin molded body 4c, the spacer 15 that blocks heat between the inner diameter portion (opening edge of the through hole 1a) of the first thermistor 1 and the lead wire 5a. Should be interposed.

In the heat dissipating portion 12 of the second embodiment shown in FIG. 4B, the lead wires 5a, 5a are supported by the columnar support 15 and this is supported in the center of the through hole 1a of the first thermistor 1. Holding the position, the inner diameter portion of the first thermistor 1 (through hole 1a
From the opening edge) to the lead wires 5a, 5a. As shown in FIG. 4C, the first thermistor 1
From the inner diameter portion (opening edge of the through hole 1a) of the lead wires 5a, 5
When the distances to a are the same, as shown in FIG. 4D, as compared with the case where the lead wire 5a is offset to the inner diameter portion of the first thermistor 1 (opening edge of the through hole 1a), the first thermistor The amount of heat transferred from 1 to the resin molded body 4c can be reduced.

Further, in order to reduce the heat transfer amount of the A route and the B route, the thermal influence on the thermistor 5 can be reduced by increasing the heat dissipation of the thermistor 1 in the C route direction. Therefore, the third embodiment has a heat dissipation path, and the heat dissipation path (C route) increases the amount of heat conducted to the connector portion 7 side through the electrode plates 3 and 2 springs. In the heat dissipation path (C route) of the third embodiment shown in FIG. 1, the plate thickness of the electrode plate 3 is increased or the diameter of the spring 2 is increased to further increase the plate thickness of the electrode plate 3 and the spring. By increasing the diameter of 2, the amount of heat conducted to the connector portion 7 side is increased.

In the above, the heat dissipating portion 12 of the first embodiment for reducing the influence of the heat from the case 4 and the heat dissipating portion of the second embodiment for reducing the influence of the heat transmitted through the resin molding 4c (lead wire 5a). 12 and the heat dissipation path of the third embodiment that conducts heat to the connector portion 7 side to reduce the influence of the heat have been described separately, but the heat dissipation portion 12 of the first embodiment and the heat dissipation portion of the second embodiment are described. 12 or a combination of the heat dissipation portion 12 of the first embodiment and the heat dissipation path of the third embodiment, and further, the heat dissipation portion 12 of the first embodiment, the heat dissipation portion 12 of the second embodiment, and the heat dissipation of the third embodiment. The combination with the path effectively suppresses thermal interference from the first thermistor 1 to the second thermistor 5.

When a voltage of 14 V is applied to the first thermistor 1 via a series resistance of 51 Ω at the sensor ambient temperature of 110 ° C. and the first thermistor 1 self-heats, the first thermistor 1 is turned on. The heat-dissipating part 12 of Example 1, the heat-dissipating part 12 of Example 2, and the heat-dissipating path of Example 3 were combined by immersing in the silicone oil 13 in the case 4 to reduce the variation in characteristics. As a result, by suppressing the thermal interference from the first thermistor 1 to the second thermistor 5, the error of the resistance ratio is significantly reduced as shown in FIG. 7, and the effect of the present invention was confirmed.

Although the present invention is used for detecting the liquid temperature of the automobile engine cooling system in the embodiment, the present invention is not limited to this.

[0043]

As described above, according to the present invention, the amount of heat in the heat conduction path from the first thermistor to the second thermistor is reduced, so that the second thermistor is self-heated by the first thermistor. It is possible to suppress heat interference with the liquid, prevent detection of temperatures other than the liquid temperature, and accurately measure the liquid temperature.

[Brief description of drawings]

FIG. 1 is a sectional view showing an embodiment of the present invention.

FIG. 2 is a sectional view showing a modified example of the present invention.

FIG. 3 is a diagram showing an experimental result when the distance between the thermistors in the present invention is increased.

FIG. 4 (a) is a diagram showing an experimental result when the distance between the thermistor and the resin molded body in the present invention is enlarged,
(B) is a perspective view showing a structure for installing the resin molded product of the present invention at a central position in a through hole of a thermistor,
(C), (d) is explanatory drawing for clarifying (b) experimental result.

FIG. 5 is a cross-sectional view showing a composite sensor used as an experimental object of the present invention.

FIG. 6 is a diagram showing an effect of the fin in the present invention.

FIG. 7 is a diagram showing an effect of the present invention.

FIG. 8 is a diagram showing a defect in the conventional example.

FIG. 9 is a diagram showing a temperature distribution in a case of a composite sensor.

[Explanation of symbols]

 1 First Thermistor 2 Spring 3 Electrode Plate 4 Case 5 Second Thermistor 5a Lead Wire 6 Support Seat 7 Connector Section 8 Storage Section

Claims (5)

[Claims] 1. A composite sensor having a first thermistor and a second thermistor, a case, a connector section, and a heat dissipation section, wherein the first thermistor and the second thermistor have different characteristics. The temperature is measured, the first thermistor is formed in a ring shape having a through hole in the central portion, and the case is a hollow container having a support seat and a storage portion. The seat supports the first thermistor and holds the thermistor in a position inside the case retracted from the tip of the case, and the storage portion is provided at a position protruding from the support seat to the tip side of the case. The second thermistor is housed and held at a position in a case different from that of the first thermistor, and the connector portion closes the opening of the case and is attached to the case support seat. Note that the second thermistor is fixed in the case accommodating portion by penetrating the through hole of the first thermistor, and has an electrode plate and a spring. The electrode plate is attached to the end face of the first thermistor. The spring is for pressing the first thermistor to the case support seat via the electrode plate and electrically connected to the electrode plate, and the heat dissipating portion is for connecting the first heat transfer part to the first plate. By reducing the amount of heat in the heat conduction path from the thermistor to the second thermistor,
A composite sensor, which suppresses thermal interference with the second thermistor due to self-heating of the first thermistor. 2. The heat dissipation portion has an outer heat conduction path, and the outer heat conduction path is a surface area of a case forming a heat conduction path from the first thermistor to the second thermistor. The composite sensor according to claim 1, wherein the composite sensor has a larger heat dissipation rate. 3. A composite sensor having an inner heat conduction path, wherein the inner heat conduction path passes through at least a lead wire passing through a through hole of the first thermistor and reaching the second thermistor. The composite sensor according to claim 2, which reduces the amount of heat conducted to the thermistor No. 2. 4. A composite sensor having a heat dissipation path, wherein the heat dissipation path has an increased amount of heat conducted to the connector portion side through the electrode plate and the spring. The described composite sensor. 5. A composite sensor having an inner heat conduction path and a heat radiation path, wherein the inner heat conduction path penetrates a through hole of the first thermistor and reaches at least the second thermistor. The amount of heat conducted to the second thermistor through the lead wire is reduced, and the heat dissipation path is one in which the amount of heat conducted to the connector portion side through the electrode plate and the spring is increased. The composite sensor according to claim 2.