JP2020038083A - Airflow sensor unit - Google Patents

Abstract

To suppress the occurrence of dew condensation in a flow channel of an airflow sensor unit.SOLUTION: The airflow sensor unit includes: a sensor housing 2 having a flow channel 21b into which air flows; an airflow sensor 4 for detecting the flow rate of the air in the flow channel 21b; and a heater 8 for heating the flow channel 21b.SELECTED DRAWING: Figure 3

Description

  The present invention relates to an airflow sensor unit.

  2. Description of the Related Art Conventionally, an airflow sensor unit that detects an amount of air taken in from outside (amount of intake air) has been known. The housing of the airflow sensor unit has a portion in which the electronic device is incorporated and a channel portion through which the taken-in air passes. An airflow sensor for detecting an intake air amount is provided in a flow path portion (for example, see Patent Document 1).

JP 2010-528303 A

  By the way, when the air taken in from the outside is higher in temperature and humidity than the temperature in the airflow sensor unit and there is a large temperature difference between the two temperatures, dew condensation may occur on the surface of the airflow sensor. If dew condensation occurs on the surface of the airflow sensor, the airflow sensor may mistake the state where air is taken in as the state where air is being exhausted, and cannot accurately detect the amount of intake air. An accurate signal relating to the intake air amount is not transmitted from the airflow sensor.

  Then, this invention is made | formed in view of the said subject, and an object of this invention is to provide the airflow sensor unit which suppresses generation | occurrence | production of the condensation in a flow path.

  In order to solve the above problems, an airflow sensor unit according to the present invention includes a sensor housing having a flow path into which air flows, an airflow sensor that detects a flow rate of the air in the flow path, and And a heater for heating. According to this aspect, the temperature in the flow path is raised, the temperature difference between the temperature in the flow path and the temperature of the inflow air is reduced, the occurrence of dew condensation in the airflow sensor is suppressed, and the amount of intake air is reduced. The airflow sensor can accurately detect the airflow.

  The sensor housing may include a housing for accommodating the airflow sensor, and a cover provided with the heater and detachable from the housing. According to this aspect, when a malfunction occurs in the heater, the cover can be removed and replaced with a new cover, and it is not necessary to replace the entire airflow sensor unit. Therefore, maintenance work is easy, and maintenance is easy. Costs can be reduced.

  The cover may be made of metal. According to this aspect, the heat transfer from the cover having the heater is good, and the flow path can be quickly heated.

The airflow sensor unit may be provided in a vehicle having an internal combustion engine, and may include a control unit that drives the heater when the internal combustion engine starts. According to this aspect, since the flow passage is heated by the heater when the internal combustion engine is started, the air flowing through the flow passage is also warmed. As a result, it is possible to prevent the occurrence of dew condensation in the flow passage regardless of the environment in which the vehicle travels, so that the airflow sensor detects an accurate intake air amount and supplies an appropriate amount of fuel to the intake air amount. The mixture can be supplied to form an air-fuel mixture having an appropriate air-fuel ratio.

  ADVANTAGE OF THE INVENTION According to this invention, generation | occurrence | production of dew condensation can be suppressed and the intake air amount can be detected correctly.

It is a schematic diagram showing an example of composition of an exhaust gas recirculation device to which an airflow sensor unit concerning an embodiment of the invention is attached. It is a perspective view of an airflow sensor unit concerning an embodiment of the invention. It is a perspective view showing the state where the airflow sensor unit concerning an embodiment of the invention was partially opened. It is a perspective view of an airflow sensor provided in an airflow sensor unit concerning an embodiment of the invention. FIG. 4 is a schematic block diagram for explaining a method of driving a heater in the airflow sensor unit according to the embodiment of the present invention.

  A preferred embodiment of the present invention will be described with reference to the drawings. The embodiment described below is one example, and various embodiments can be taken within the scope of the present invention.

  FIG. 1 is a diagram schematically showing an exhaust gas recirculation device 100 to which an airflow sensor unit 1 according to the present embodiment is attached. The configuration of the exhaust gas recirculation device to which the airflow sensor unit 1 is attached is not limited to this. The airflow sensor unit 1 is used in an exhaust gas recirculation device 100 mounted on a vehicle having an internal combustion engine 110.

  The exhaust gas recirculation device 100 includes an intake pipe 120, a temperature sensor 121, an intake pressure sensor 122, a filter 123, and an airflow sensor unit 1 on the intake side, and an exhaust pipe 130 on the exhaust side. It has an exhaust brake 131 and a lambda sensor 132. In the exhaust gas recirculation device 100, a communication path 140 and a variable turbo 150 having a known / known configuration are provided between the intake pipe 120 and the exhaust pipe 130.

  The intake pipe 120 is connected to an intake manifold 111 of the internal combustion engine 110 to take in air for forming a mixture with fuel. The exhaust pipe 130 is connected to an exhaust manifold 112 for discharging exhaust gas from the internal combustion engine 110. In the present embodiment, airflow sensor unit 1 detects the amount of air taken in from outside the vehicle and flowing through intake pipe 120.

  The communication path 140 connects the intake pipe 120 and the exhaust pipe 130. The communication passage 140 is provided at an appropriate position between the intake pipe 120 and the exhaust pipe 130. The variable turbo 150 is provided upstream of the communication path 140 in the intake pipe 120 and downstream of the communication path 140 in the exhaust pipe 130. The variable turbo 150 has a variable turbine 151 and a compressor 152. The variable turbine 151 is provided downstream of the communication passage 140 in the exhaust pipe 130, and the compressor 152 is provided upstream of the communication passage 140 in the intake pipe 120. The compressor 152 is rotated by the rotational force of the variable turbine 151, and the taken-in air is sent to the intake manifold 111 as compressed air.

The filter 123 is provided for purifying air taken in on the upstream side of the intake pipe 120. On the downstream side of the filter 123, an airflow sensor unit 1 for detecting an intake amount of air flowing in through the filter 123 is provided.

  Temperature sensor 121 is provided in intake pipe 120 between communication path 140 and variable turbo 150, and measures the temperature of air taken into internal combustion engine 110. The intake pressure sensor 122 is provided downstream of the temperature sensor 121 in the intake pipe 120, and measures the intake pressure in the intake manifold 111.

  The exhaust brake 131 is provided in the exhaust pipe 130 on the downstream side of the variable turbine 151, and blocks the flow of exhaust gas. The lambda sensor 132 is provided on the exhaust pipe 130 downstream of the exhaust brake 131.

  Measurement signals from the airflow sensor unit 1, the temperature sensor 121, the intake pressure sensor 122, and the lambda sensor 132 are input to a vehicle ECU (electronic control unit) 210, which will be described later, and are used for fuel injection control processing and the like.

  FIG. 2 is a perspective view of the airflow sensor unit 1 according to the present embodiment. FIG. 3 is a perspective view showing the airflow sensor unit 1 with the flow path cover 31 and the substrate cover 32 removed. The airflow sensor unit 1 has a so-called plug-in type structure. The airflow sensor unit 1 includes a sensor housing 2, an airflow sensor 4, and a substrate 6. The sensor housing 2 has a flow path 21b into which air flows. The airflow sensor 4 detects the flow rate of air in the flow path 21b. Various circuits are formed on the substrate 6.

  The sensor housing 2 is formed of an insulating material such as a resin, and has a substantially flat columnar overall appearance. The sensor housing 2 has a housing 20, a flow path cover 31, and a substrate cover 32. The housing 20 is integrally formed by a suction part 21, a board accommodation part 22, and a cable connection part 23. The flow path cover 31 is detachable from the housing 20 and is attached to the housing 20 to close the intake section 21. The board cover 32 is detachable from the housing 20 and is attached to the housing 20 to close the board accommodating portion 22.

  In the airflow sensor unit 1, when viewed in the insertion direction In into the intake pipe 120, the cable connection portion 23 is disposed on the upstream side, and the intake portion 21 is disposed on the downstream side. The board accommodating portion 22 is disposed between the suction portion 21 and the cable connection portion 23 in the insertion direction In. The airflow sensor unit 1 is attached to the intake pipe 120 such that the entire longitudinal axis x direction (the vertical direction in FIG. 2 and FIG. 3) substantially matches the insertion direction In.

  The intake section 21 can be inserted into a connection member (not shown) provided in the intake pipe 120 for connecting the airflow sensor unit 1. The suction part 21 is fitted and fixed to the connection member by insertion into the connection member. When the airflow sensor unit 1 is attached to the intake pipe 120, the intake section 21 is located inside the intake pipe 120.

  The housing 20 accommodates an airflow sensor 4 to be described later in the intake section 21, and a bypass passage 21a, a flow passage 21b, and a suction port 21c are integrally formed. In the intake section 21, the airflow sensor 4 detects the amount of intake air taken in. The housing 20 is formed such that one surface side of the pair of flat surfaces in the intake section 21 is open. On the open side, the intake section 21 is closed by attaching a flat channel cover 31 to be described later. When closed by the flow path cover 31, the suction port 21c of the suction section 21 is open.

Inside the intake section 21, a bypass passage 21a extends from the intake port 21c to the inside along a direction orthogonal to the longitudinal axis x direction. A bypass hole 21d that opens to the outside of the housing 20 is formed at an end position of the bypass passage 21a provided at an appropriate length. In the bypass passage 21a, a flat metal plate 21e for collecting charged dust is provided near the bypass hole 21d.

  The flow path 21b communicates with the bypass passage 21a in the vicinity of the suction port 21c and is formed to extend to a portion where the airflow sensor 4 is disposed. The flow path 21b extends from a portion where the airflow sensor 4 is disposed to a side opposite to the suction port 21c. The flow path 21b extends to the opposite side to the suction port 21c, and is bent downward so as to change the guide direction of the taken-in air by 180 °. An end portion 21f is provided at an end position of the flow path 21b that is turned 180 ° and extends. A main bypass hole 21g that opens to the outside of the housing 20 is formed in the terminal end 21f. The air that has entered the airflow sensor unit 1 is returned to the intake pipe 120 through the main bypass hole 21g.

  The air in the intake pipe 120 flows into the airflow sensor unit 1 through the intake port 21c. The suction port 21 c is provided on the side facing the upstream side of the housing 20 in the flow direction of the air flowing through the intake pipe 120. The suction port 21c is opened along the longitudinal axis x at a position below the housing 20 in the longitudinal axis x direction.

  The vehicle may travel between areas having different environments depending on the purpose. For example, when the vehicle moves from an area where the air is relatively low in temperature and humidity to an area where the air is relatively hot and humid, the temperature of the taken hot and humid air and the temperature in the flow path 21 b of the intake unit 21 are compared. The temperature difference becomes large, and a situation occurs in which dew condensation easily occurs in the flow path 21b. Therefore, the airflow sensor unit 1 further includes a heater 8. The heater 8 is provided on the flow path cover 31 and heats the flow path 21b.

  By providing the heater 8, the flow path 21b is quickly heated by the heater 8 when the internal combustion engine 110 is started, and the temperature in the flow path 21b becomes higher than the temperature before the heater 8 is turned on. As the temperature in the flow path 21b increases, the temperature difference between the temperature in the flow path 21b and the temperature of the taken-in air decreases, and the occurrence of dew condensation on the airflow sensor 4 in the flow path 21b is suppressed. be able to. Thereby, the air entering the flow path 21b is also warmed, and the air flow sensor 4 can accurately detect the intake air amount regardless of the environment in which the vehicle travels. The mixture can be supplied to form an air-fuel mixture suitable for the operation state of the internal combustion engine 110.

  The heater 8 is formed of a copper wire. In addition, the heater 8 is not limited to copper, and may be formed of, for example, a copper alloy, silver, aluminum, platinum, or an alloy thereof as long as the material is a metal material having a high electric resistivity.

  The heater 8 is attached to an outer surface of a channel cover 31 described later. In a direction orthogonal to the longitudinal axis x, two connection ends 81 and 82 of the heater 8 are arranged on the substrate accommodating portion 22 side of the flow path cover 31 at a predetermined interval with respect to the longitudinal axis x. ing. Both connection ends 81 and 82 of the heater 8 are connected to a power supply pin (not shown) and a ground pin (not shown) in the substrate housing portion 22, respectively.

The heater 8 extends downward from one connection end 81 along the longitudinal axis x, and is bent toward the longitudinal axis x near the lower edge of the flow path cover 31. The bent heater 8 extends to a position below the other connection end portion 82 and reciprocates (meanders) a plurality of times in the region between the two connection end portions 81 and 82, and moves upward in the longitudinal axis x direction. Extending. When the heater 8 is supplied with power (ON control), the heater 8 generates heat and the flow path 21
b Heat the inside.

  The path through which air flows in the flow path 21b is defined by the intake section 21 and the flow path cover 31 that closes the intake section 21. When the flow path cover 31 is attached to the housing 20, the path of the intake section 21 The inside is not exposed to the outside. Since the flow path cover 31 is formed of aluminum, it is excellent in heat transfer by the heater 8, and can quickly heat the flow path 21b after the internal combustion engine 110 is started. The flow path cover 31 is not limited to aluminum, and may be formed of a metal such as an aluminum alloy, copper, silver, or an alloy thereof as long as the metal is excellent in heat transfer.

  Since the heater 8 is provided in the flow path cover 31, when a problem occurs in the heater 8, the flow path cover 31 is removed and replaced with a new flow path cover 31 having a normal heater 8. Often, there is no need to replace the entire airflow sensor unit 1. For this reason, the maintenance work of the airflow sensor unit 1 is easy and the maintenance cost can be suppressed.

  The board 6 on which the electronic circuit is mounted is housed in the board housing section 22. The substrate 6 has a power supply circuit (not shown) for the heater element 45 of the airflow sensor 4, which will be described later, and converts the resistance value change of the two resistance elements 46a and 46b according to the intake air amount into a required voltage change. A signal conversion circuit (not shown) is formed. The board 6 is a printed board on which an electronic circuit is formed by a so-called printed wiring technique or the like. A power supply pin (not shown) and a ground pin (not shown) connected to the connection ends 81 and 82 of the heater 8 are arranged in the substrate housing portion 22.

  The housing 20 is open on the same side as the open side of the air intake section 21 in the substrate housing section 22. The board cover 32 is attached to the housing 20 to close the board accommodating portion 22 from the open side. The board cover 32 is formed of an insulating material such as a resin, similarly to the housing 20.

  The cable connection unit 23 supplies the output signal of the electronic circuit mounted on the board 6 to the electronic control unit 210 (see FIG. 5) for executing operation control of the vehicle, so that the airflow sensor unit 1 and the electronic control unit 210 Are electrically connected via a signal cable (not shown).

  A plurality of module-side connection terminals (not shown) for outputting a signal to the outside while being connected to the substrate 6 are built in the cable connection portion 23. The module-side connection terminal is connected to a cable-side connection terminal (not shown) made of a conductive member provided on a signal cable (not shown).

  FIG. 4 is a perspective view of the airflow sensor 4. The airflow sensor 4 is provided inside the intake section 21 near the substrate accommodating section 22 in the flow path 21b. The airflow sensor 4 has a base 41 formed in a roughly columnar shape using a semiconductor member. Two notches 42a and 42b are formed in the central portion of the base 41 at appropriate intervals in the longitudinal axis y direction of the base 41 (the left-right direction in the drawing of FIG. 4).

Between the two notches 42a and 42b, a heater installation part 43 and two resistance element installation parts 44a and 44b are provided. The heater installation section 43 is provided between the two resistance element arrangement sections 44a and 44b in the longitudinal axis y direction. The surfaces of the heater installation section 43 that are in contact with the resistance element installation sections 44a and 44b are formed as slopes inclined toward the bottom surfaces of the cutout sections 42a and 42b, respectively. A heater element 45 using a semiconductor member is formed on the upper surface of the heater installation section 43. Resistive elements 46a and 46b using semiconductor members are formed on the upper surfaces of the resistive element disposition portions 44a and 44b.

  The height (vertical direction in the drawing) of the heater installation section 43 and the resistance element installation sections 44a and 44b is set so that the heater element 45 and the resistance elements 46a and 46b are located on the same plane. I have. The heater element 45 and the resistance elements 46a and 46b are arranged so that the air passes through the resistance element 46a, the heater element 45, and the other resistance element 46b in this order along the flow F of the taken air. I have. The airflow sensor 4 detects the amount of intake air based on the difference between the resistance values of the two resistance elements 46a and 46b.

  FIG. 5 is a schematic block diagram for explaining a method of turning on the heater 8. The airflow sensor unit 1 has a control unit 220 that turns on the heater 8. When the ignition switch 200 is started to start the internal combustion engine 110, an ignition signal is transmitted from the ignition switch 200 to the electronic control unit 210 to notify that the internal combustion engine 110 has been started. The electronic control unit 210 that has received the ignition signal from the ignition switch 200 transmits a heating signal to the control unit 220 of the airflow sensor unit 1 via the main control unit 211 to instruct the control unit 220 of the airflow sensor unit 1 to heat the flow path 21 b by the heater 8.

  The control unit 220 that has received the heating signal transmits a power supply signal instructing power supply to the heater 8 to a predetermined power supply system, and turns on the heater 8. The control unit 220 receives a signal from the electronic control unit 210 when the ignition switch 200 of the internal combustion engine 110 is activated, and supplies a predetermined power to the power supply pin to which one connection end of the heater 8 is connected. Send a signal to the power supply system. As a result, power supply to the heater 8 is started, and the heater 8 generates heat to heat the flow path 21b.

  Note that the present invention is not limited to the above-described embodiment, and can be appropriately changed without departing from the scope of the present invention. For example, in the above embodiment, the heater 8 is provided on the outer surface of the flow path cover 31, but may be provided on the inner surface of the flow path cover 31. When the channel cover 31 is formed by bonding two metal plate members to each other, the heater 8 may be interposed between the plate members.

  Further, in the above embodiment, the flow path cover 31 is formed of a metal material, but may be formed by, for example, an injection molding method using a resin material. In this case, the heater 8 is embedded inside the material of the flow path cover 31.

  In the above-described embodiment, the heater 8 is turned on when the internal combustion engine 110 is started, that is, when the ignition switch 200 is started. It may be turned on accordingly. The outside air temperature is measured by a temperature sensor provided in the vehicle and measuring the outside air temperature. The measured outside air temperature is stored in the electronic control unit 210. When the internal combustion engine 110 is started, the electronic control unit 210 compares the outside air temperature of the vehicle with a predetermined reference temperature. Only when the outside air temperature is lower than the reference temperature, a heating signal may be transmitted from the electronic control unit 210 to the control unit 220, and the heater 8 may be turned on.

  Further, in the above-described embodiment, the airflow sensor unit 1 is used in a vehicle. However, the airflow sensor unit 1 is not limited to the vehicle as long as it is a portion that detects an intake amount of air sucked from the outside. Is also good.

DESCRIPTION OF SYMBOLS 1 Airflow sensor unit 2 Sensor housing 20 Housing 21b Flow path 31 Flow path cover (cover)
4 Airflow sensor 6 Substrate 8 Heater 220 Control unit

Claims (4)

A sensor housing having a flow path into which air flows,
An airflow sensor that detects a flow rate of the air in the flow path,
A heater for heating the flow path;
An airflow sensor unit comprising: The sensor housing,
A housing for accommodating the airflow sensor;
A cover provided with the heater and detachable from the housing;
The airflow sensor unit according to claim 1, comprising:   The airflow sensor unit according to claim 2, wherein the cover is made of metal.   The said airflow sensor unit is provided in the vehicle which has an internal combustion engine, and is provided with the control part which turns on the said heater when the said internal combustion engine starts, The Claim 1 characterized by the above-mentioned. Airflow sensor unit.

Images