JP2015087196A - Temperature control device for heater for temperature/humidity sensor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a humidity detection device of which the measurement accuracy is improved.SOLUTION: The humidity detection device includes a housing member and an electronic circuit board that is accommodated in the housing member and includes a heating resistor, a temperature/humidity sensor and a circuit component. The electronic circuit board includes: a first board end portion in which the circuit component is packaged; and a second board end portion for the heating resistor and the temperature/humidity sensor. A surface area of the second board end portion is smaller than that of the first board end portion, the heating resistor heats the second board end portion in which the temperature/humidity sensor is provided, and heating control is performed on the basis of a temperature detected by the temperature/humidity sensor.

Description

  The present invention relates to a humidity detection device that measures humidity, and more particularly to a detection device suitable for measuring the temperature and humidity of intake air of an internal combustion engine.

  Conventionally, there is a polymer electric capacitance type temperature / humidity sensor in which a sensor element made of a polymer is formed on a substrate and the humidity of the atmosphere is measured from a change in the capacitance value of the element. This temperature / humidity sensor is capable of detecting even low humidity, is relatively accurate, and is low in cost. Therefore, it is widely used as a detection sensor for atmospheric humidity from consumer to industrial measuring instruments. .

  In the automotive field, for example, a temperature / humidity measurement device and a pressure measurement device are integrated as a sensor capable of measuring multiple physical quantities by integrating an intake air flow rate measurement device for an internal combustion engine with a temperature / humidity detection device. Is described in Patent Document 1. Furthermore, Patent Document 2 describes a humidity sensor including a heating unit for the purpose of removing moisture from the humidity sensor.

JP 2010-43883 A JP 2008-39550 A

  An automobile using an electronically controlled fuel injection system has become commonplace. In this case, various sensors and control devices are arranged inside the engine room.

  One of them is a humidity detection device. Humidity detection devices have only recently been used for fuel control applications, and have been used mainly for air conditioning management in vehicle interiors. The humidity detector provided in the passenger compartment has no requirement for durability assuming a harsh environment. On the other hand, when the humidity detector is used for engine fuel control, When used in combination with other sensors, environmental resistance equivalent to the intake air flow rate measuring device is required. In particular, there are unfavorable environments for temperature / humidity sensors installed in humidity detectors, such as contamination of detector elements and adhesion of water droplets to humidity detectors that are caused by condensation. Necessary.

  In the technique described in Patent Document 2, when used under severe conditions of an internal combustion engine such as an engine, even if moisture removal of the moisture sensitive film portion is possible, it is considered with respect to the adhesion of fouling substances such as carbon. Absent. When the detection element of the humidity detection device is soiled, a significant delay occurs in the detection responsiveness to changes in humidity, leading to a decrease in humidity measurement accuracy. Furthermore, the humidity detecting device may lose its function.

  In addition, since the temperature / humidity sensor itself is at the ambient temperature, when the ambient temperature reaches the dew point, condensed water adheres to the surface of the temperature / humidity sensor such as the moisture sensitive portion or the substrate, resulting in a dew condensation state. When the temperature / humidity sensor is condensed, a signal value indicating the maximum or minimum humidity is output. However, the humidity cannot be detected accurately until the detection element section dries, and the function as a humidity detection device is temporarily set. Lose.

  As a result, the engine control system may be adversely affected during the period when the humidity detection device has lost its function. In particular, in an environment where the atmosphere in a vehicle intake pipe or the like changes rapidly, this problem is remarkable when a polymer electric capacitance type temperature and humidity sensor is used.

  Further, as described in Patent Document 2, when a humidity sensor is mounted on an electronic circuit board as it is when moisture is removed, the heat to be heated causes heat to escape to the electronic circuit board, increasing the power consumption of the humidity sensor. . Therefore, there is room for improvement in terms of reducing power consumption.

  An object of the present invention is to provide a humidity detection device with improved measurement accuracy.

  In order to solve the above problems, for example, the configuration described in the claims is adopted.

  As an example, a humidity detecting device having a housing member, and an electronic circuit board that is housed in the housing member and includes a heating resistor, a temperature / humidity sensor, and circuit components, the electronic circuit board is provided. Comprises a first board end on which the circuit components are mounted, the heating resistor and the temperature / humidity sensor second board end, and the second board end comprises The surface area is smaller than the end portion of the first substrate, and the heating resistor heats the end portion of the second substrate including the temperature / humidity sensor, and heats based on the temperature detected by the temperature / humidity sensor. Take control.

  ADVANTAGE OF THE INVENTION According to this invention, it becomes possible to provide the humidity detection apparatus which improved the measurement precision.

It is an inclination figure of the temperature control apparatus of the heater for temperature / humidity sensors by one Example of this invention. It is a block diagram of the temperature control apparatus of the heater for temperature / humidity sensors by one Example of this invention. The board | substrate enlarged plan view for demonstrating the circuit part and sensor heating part by one Example of this invention The block diagram which shows the temperature control means of the heater by one Example of this invention

  Hereinafter, embodiments of the present invention will be described with reference to FIGS.

  As shown in FIG. 1 and FIG. 2, in the humidity detection device exposed to the intake pipe or the dedicated body composed of the two parts of the housing 3 and the cover 2, the humidity detection device arranges the electronic circuit board 15. A first sub-passage 21 for taking in part of the air flowing in the pipe, an inflow passage (upstream) 20A from the first sub-passage 21 to the second sub-passage 22 and a second sub-passage 22 to the first sub-passage 21 An inflow passage (downstream).

  The housing 3 includes a connector 1 for fitting with a harness of the engine control device, a housing support portion 4 fixed to the intake pipe or the dedicated body, and the intake pipe or dedicated body and the housing support portion 4 are fixed by metal screws or the like. A metal bush 5 for reinforcement, a first sub-passage 21 for taking in part of the air flowing through the intake pipe, and an inner wall shape for forming the second sub-passage 22. Generally, an inexpensive resin material is used as a material for forming the housing 3. Here, the second sub-passage 22 has a role of taking in a part of the air flowing through the first sub-passage 21 and bypassing it.

  Next, an example of a temperature control device for a temperature / humidity sensor heater of a humidity detection device capable of deteriorating measurement accuracy due to fouling and dew condensation, and further generation of combined fouling and dew condensation with low power consumption will be described. The description of the components having the same functions as those shown in FIGS. 1 and 2 and already described in FIGS. 1 and 2 will be omitted.

  FIG. 3 is an enlarged plan view of the substrate for explaining the circuit unit and the sensor heating unit of the present embodiment.

  As shown in FIG. 3, the first substrate end portion 30 and the second substrate end portion 31 are separated on the same electronic circuit board 15 by the heat separating portion 33, and the heat generated by the heating resistor 13 causes the substrate to be medium. As a main structure, heat is transferred to the temperature and humidity sensor 14. Here, a circuit component such as the microprocessor 12 is mounted on the first substrate end portion 30. Further, the temperature / humidity sensor 14 is provided on the second substrate end portion 31, and the heating resistor 13 is provided on the upstream side of the temperature / humidity sensor 14. The second substrate end portion 31 has a structure having a smaller surface area than the first substrate end portion.

  The second substrate end portion 31 is exposed to the intake air and is a heating resistor mounted on the upstream side by the intake air flowing from the first sub passage 21 into the inflow passage (upstream) 20A of the second sub passage 22. The heat dissipated from 13 is transmitted to the temperature / humidity sensor 14 mounted on the downstream side of the heating resistor 13 by convective heat transfer.

  FIG. 4 is a block diagram showing the temperature control means of the heater of this embodiment.

  The temperature / humidity sensor 14 detects the temperature of the humidity detection part in addition to the humidity detection, and transmits the temperature information to the microprocessor 12 using a signal line (for temperature / humidity sensor control) 32A. Based on the temperature information, the heater is controlled using a signal line (for heater control) 32B. Combined with the above two structures, by controlling the heater using the temperature of the temperature / humidity sensor, the measurement accuracy due to contamination, condensation, and the combined occurrence of contamination and condensation, compared to conventional humidity sensors used in the same environment Can be reduced with low power consumption.

  As described above, even in an environment where the atmosphere of the vehicle or the like changes suddenly, the response delay from the contamination of the temperature / humidity sensor and the condensation is shortened, and the responsiveness of the internal combustion engine control using such information is improved. This makes it possible to measure the intake air temperature and humidity with high reliability that can guarantee performance even in harsh environments such as gasoline engine systems and diesel engine systems that have been difficult so far. Contributes to gas reduction.

  In addition, degradation of measurement accuracy due to fouling, condensation, and the combined occurrence of fouling and condensation can be achieved with low power consumption, and the response delay from fouling and condensation of the temperature and humidity sensor can be shortened. It is possible to provide a temperature control device for a temperature / humidity sensor heater that is optimal for improving the responsiveness of internal combustion engine control using information and reducing the power consumption of the temperature / humidity sensor.

DESCRIPTION OF SYMBOLS 1 ... Connector 2 ... Cover 3 ... Housing 4 ... Housing support part 5 ... Metal bush 6A ... Intake air inlet 6B ... Intake air outlet 10 ... Metal wire 11. ..Metal pad 12 ... Microprocessor 13 ... Heat generating resistor 14 ... Temperature / humidity sensor 15 ... Electronic circuit board 20A ... Inflow passage from the first sub-passage to the second sub-passage (upstream) )
20B: Inflow passage from the second sub-passage to the first sub-passage (downstream)
21 ... 1st subpassage 22 ... 2nd subpassage 30 ... 1st board | substrate edge part 31 ... 2nd board | substrate edge part 32A ... Signal wire (for temperature / humidity sensor control)
32B Signal line (for heater control)
33 ... Thermal separation part

Claims (5)

A humidity detection device having a housing member, and an electronic circuit board that is housed in the housing member and includes a heating resistor, a temperature / humidity sensor, and a circuit component,
The electronic circuit board includes a first board end on which the circuit component is mounted, a heating resistor, and a temperature and humidity sensor second board end.
The second substrate end has a smaller surface area than the first substrate end,
The said heat generating resistor heats said 2nd board | substrate edge part provided with the said temperature / humidity sensor, and performs a heating control based on the temperature which the said temperature / humidity sensor detected, The humidity detection apparatus characterized by the above-mentioned. In the humidity detection apparatus according to claim 1,
The said electronic circuit board has the thermal separation part thermally separated between said 1st board | substrate edge part part and said 2nd board | substrate edge part part, The humidity detection apparatus characterized by the above-mentioned. In the humidity detection apparatus according to claim 2,
A first sub-passage for taking in part of the intake air;
A humidity detection device comprising a second sub-passage branched from the first sub-passage and in which the temperature / humidity sensor is arranged. In the humidity detection apparatus of Claim 3,
At least one heat generating resistor is mounted on the upstream side of the air flow with respect to the temperature / humidity sensor. In the humidity detection apparatus according to claim 4,
The humidity detecting device, wherein the heating resistor comprises a chip resistor.