US20200033170A1 - Flow measuring device measuring air flow through a bypass passage throttled by a throttle portion - Google Patents
Flow measuring device measuring air flow through a bypass passage throttled by a throttle portion Download PDFInfo
- Publication number
- US20200033170A1 US20200033170A1 US16/591,911 US201916591911A US2020033170A1 US 20200033170 A1 US20200033170 A1 US 20200033170A1 US 201916591911 A US201916591911 A US 201916591911A US 2020033170 A1 US2020033170 A1 US 2020033170A1
- Authority
- US
- United States
- Prior art keywords
- bypass passage
- flowing
- sub
- sensing surface
- surface portion
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Abandoned
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Classifications
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01F—MEASURING VOLUME, VOLUME FLOW, MASS FLOW OR LIQUID LEVEL; METERING BY VOLUME
- G01F1/00—Measuring the volume flow or mass flow of fluid or fluent solid material wherein the fluid passes through a meter in a continuous flow
- G01F1/68—Measuring the volume flow or mass flow of fluid or fluent solid material wherein the fluid passes through a meter in a continuous flow by using thermal effects
- G01F1/684—Structural arrangements; Mounting of elements, e.g. in relation to fluid flow
- G01F1/6842—Structural arrangements; Mounting of elements, e.g. in relation to fluid flow with means for influencing the fluid flow
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
- F02D—CONTROLLING COMBUSTION ENGINES
- F02D41/00—Electrical control of supply of combustible mixture or its constituents
- F02D41/02—Circuit arrangements for generating control signals
- F02D41/18—Circuit arrangements for generating control signals by measuring intake air flow
- F02D41/187—Circuit arrangements for generating control signals by measuring intake air flow using a hot wire flow sensor
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
- F02D—CONTROLLING COMBUSTION ENGINES
- F02D9/00—Controlling engines by throttling air or fuel-and-air induction conduits or exhaust conduits
- F02D9/08—Throttle valves specially adapted therefor; Arrangements of such valves in conduits
- F02D9/10—Throttle valves specially adapted therefor; Arrangements of such valves in conduits having pivotally-mounted flaps
- F02D9/1035—Details of the valve housing
- F02D9/1055—Details of the valve housing having a fluid by-pass
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
- F02M—SUPPLYING COMBUSTION ENGINES IN GENERAL WITH COMBUSTIBLE MIXTURES OR CONSTITUENTS THEREOF
- F02M35/00—Combustion-air cleaners, air intakes, intake silencers, or induction systems specially adapted for, or arranged on, internal-combustion engines
- F02M35/10—Air intakes; Induction systems
- F02M35/10373—Sensors for intake systems
- F02M35/10386—Sensors for intake systems for flow rate
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01F—MEASURING VOLUME, VOLUME FLOW, MASS FLOW OR LIQUID LEVEL; METERING BY VOLUME
- G01F1/00—Measuring the volume flow or mass flow of fluid or fluent solid material wherein the fluid passes through a meter in a continuous flow
- G01F1/68—Measuring the volume flow or mass flow of fluid or fluent solid material wherein the fluid passes through a meter in a continuous flow by using thermal effects
- G01F1/684—Structural arrangements; Mounting of elements, e.g. in relation to fluid flow
- G01F1/688—Structural arrangements; Mounting of elements, e.g. in relation to fluid flow using a particular type of heating, cooling or sensing element
- G01F1/69—Structural arrangements; Mounting of elements, e.g. in relation to fluid flow using a particular type of heating, cooling or sensing element of resistive type
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
- F02D—CONTROLLING COMBUSTION ENGINES
- F02D9/00—Controlling engines by throttling air or fuel-and-air induction conduits or exhaust conduits
- F02D9/02—Controlling engines by throttling air or fuel-and-air induction conduits or exhaust conduits concerning induction conduits
- F02D2009/0201—Arrangements; Control features; Details thereof
- F02D2009/0294—Throttle control device with provisions for actuating electric or electronic sensors
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
- F02D—CONTROLLING COMBUSTION ENGINES
- F02D2400/00—Control systems adapted for specific engine types; Special features of engine control systems not otherwise provided for; Power supply, connectors or cabling for engine control systems
- F02D2400/18—Packaging of the electronic circuit in a casing
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01F—MEASURING VOLUME, VOLUME FLOW, MASS FLOW OR LIQUID LEVEL; METERING BY VOLUME
- G01F1/00—Measuring the volume flow or mass flow of fluid or fluent solid material wherein the fluid passes through a meter in a continuous flow
- G01F1/68—Measuring the volume flow or mass flow of fluid or fluent solid material wherein the fluid passes through a meter in a continuous flow by using thermal effects
- G01F1/684—Structural arrangements; Mounting of elements, e.g. in relation to fluid flow
- G01F1/6845—Micromachined devices
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01F—MEASURING VOLUME, VOLUME FLOW, MASS FLOW OR LIQUID LEVEL; METERING BY VOLUME
- G01F5/00—Measuring a proportion of the volume flow
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01M—TESTING STATIC OR DYNAMIC BALANCE OF MACHINES OR STRUCTURES; TESTING OF STRUCTURES OR APPARATUS, NOT OTHERWISE PROVIDED FOR
- G01M15/00—Testing of engines
- G01M15/04—Testing internal-combustion engines
- G01M15/042—Testing internal-combustion engines by monitoring a single specific parameter not covered by groups G01M15/06 - G01M15/12
- G01M15/048—Testing internal-combustion engines by monitoring a single specific parameter not covered by groups G01M15/06 - G01M15/12 by monitoring temperature
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N27/00—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means
- G01N27/02—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating impedance
- G01N27/04—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating impedance by investigating resistance
- G01N27/06—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating impedance by investigating resistance of a liquid
- G01N27/08—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating impedance by investigating resistance of a liquid which is flowing continuously
- G01N27/10—Investigation or analysis specially adapted for controlling or monitoring operations or for signalling
Definitions
- the present disclosure relates to a flow measuring device that measures a flow volume of an intake air suctioned into an internal combustion engine used in a vehicle.
- a flowing measuring device includes a housing and a flow sensing chip.
- the housing includes a bypass passage introducing a part of an air flowing through an intake air channel of an internal combustion engine.
- the flow sensing chip is located in the bypass passage and includes a sensing surface portion generating an electrical signal in response to a flow volume of the air in the intake air channel by a heat transmission between the sensing surface portion and the air flowing through the bypass passage.
- the sensing surface portion is located in a direction parallel to a flowing direction of a flow of the air flowing through the bypass passage.
- the bypass passage is throttled by a throttle portion such that a cross-sectional area of the bypass passage perpendicular to the flowing direction decreases in accordance with a decrease in distance from a gravity center of the sensing surface portion to a center of the cross-sectional area in the direction parallel to the flowing direction.
- the flowing measuring device includes a housing and a flow sensing chip.
- the housing includes a bypass passage that introduces a part of an air flowing through a duct.
- the flow sensing chip is located in the bypass passage and includes a sensing surface portion that generates an electrical signal in response to a flow volume of the air in the duct by a heat transmission between the sensing surface portion and the air flowing through the bypass passage.
- the throttle portion is a part of a flowing passage wall facing the sensing surface portion.
- the throttle portion throttles the cross-sectional area of the bypass passage such that a distance from the sensing surface portion to the flowing passage wall at the cross-sectional area in a direction perpendicular to the sensing surface portion decreases in accordance with a decrease in distance from the gravity center of the sensing surface portion to the center of the cross-sectional area in the direction parallel to the flowing direction.
- a position where the throttle portion starts is referred to as a start point position
- a position of the throttle portion where a distance between the gravity center of the sensing surface portion and the throttle portion is shortest is referred to as an end point position
- the start point position and the end point position define an imagination line
- the imagination line and the flowing direction define an angle that is in a range from 0 degrees to 20 degrees.
- the flowing passage wall gradually varies in the throttle portion, it can be suppressed that a vortex or a separation is generated in the flow of the air in the vicinity of the throttle portion. Further, a disturb of the flow of the intake air generated by the throttle portion at the sensing surface portion can be suppressed. Furthermore, in the flow measuring device including the throttle portion, a sensing accuracy of the flow volume at the sensing surface portion can be improved.
- the throttle portion is a part of a flowing passage wall facing the sensing surface portion.
- a position where the throttle portion starts is referred to as a start point position, and the start point position is located upstream of the sensing portion in the flowing direction.
- the throttle portion includes a surface that is a planar surface. The surface of the throttle portion and the flowing direction define an angle that is in a range from 0 degrees to 20 degrees.
- a disturb of the flow of the intake air generated by the throttle portion at the sensing surface portion can be suppressed.
- a sensing accuracy of the flow volume at the sensing surface portion can be improved.
- the sensing portion may be a shape other than a planar shape.
- the flow measuring device includes a housing including a bypass passage that introduces a part of an air flowing through a duct, and a flow sensing chip located in the bypass passage and including a sensing surface portion that generates an electrical signal in response to a flow volume of the air in the duct by a heat transmission between the sensing surface portion and the air flowing through the bypass passage.
- the sensing surface portion is located along a flowing direction in which the air flows through the bypass passage.
- the throttle portion is a part of a flowing passage wall that is included in the housing and faces the sensing surface portion, the throttle portion throttles the cross-sectional area of the bypass passage such that a distance from the sensing surface portion to the flowing passage wall at the cross-sectional area in a direction perpendicular to the sensing surface portion decreases in accordance with a decrease in distance from the gravity center of the sensing surface portion to the center of the cross-sectional area in the direction parallel to the flowing direction.
- a position where the throttle portion starts is referred to as a start point position
- a position of the throttle portion where a distance between the gravity center of the sensing surface portion and the throttle portion is shortest is referred to as an end point position.
- the start point position and the end point position define an imagination line
- the imagination line and the flowing direction define an angle that is in a range from 0 degrees to 30 degrees.
- the flow measuring device includes a housing including a bypass passage that introduces a part of an air flowing through a duct, and a flow sensing chip located in the bypass passage and including a sensing portion that generates an electrical signal in response to a flow volume of the air in the duct.
- the bypass passage is throttled by a throttle portion such that a cross-sectional area of the bypass passage perpendicular to a flowing direction in which the air flows through the bypass passage decreases in accordance with a decrease in distance from a gravity center of the sensing surface portion to a center of the cross-sectional area in a direction parallel to the flowing direction.
- the throttle portion is a part of a flowing passage wall facing the sensing surface portion.
- a position where the throttle portion starts is referred to as a start point position, the start point position is located upstream of the sensing portion in the flowing direction.
- the throttle portion includes a surface that is a planar surface, the surface of the throttle portion and the flowing direction define an angle that is in a range from 0 degrees to 30 degrees.
- the flow measuring device measures a flow volume of an air.
- the flow measuring device includes a bypass passage through which the air flows, a sensing portion outputting an electrical signal in response to the flow volume of the air in the bypass passage, a pair of flowing passage walls facing each other, the sensing portion located between the flowing passage walls, and a throttle portion throttling the bypass passage by protruding from the flowing passage walls toward the sensing portion, in an arrangement direction in which the pair of the flowing passage walls is arranged.
- the throttle portion has a protruding dimension gradually increases in accordance with a decrease in distance from the throttle portion to the sensing portion from an upstream end of the throttle portion in the bypass passage in a flowing direction in which the air flows through the bypass passage.
- a position of an upstream end of the throttle portion is referred to as a start point position, and a position of the throttle portion where a distance between the gravity center of the sensing surface portion and the throttle portion is shortest is referred to as an end point position.
- the start point position and the end point position define an imagination line, and the imagination line and the flowing direction define an angle that is in a range from 0 degrees to 30 degrees.
- FIG. 1 is a diagram showing an outline of a flow measuring device viewed from an upstream of an intake air flow, according to a first embodiment of the present disclosure
- FIG. 2 is a cross-sectional view showing the flow measuring device along a flowing direction of an intake air, according to the first embodiment
- FIG. 3 is a cross-sectional view showing the flow measuring device and taken along a line in FIG. 2 , according to the first embodiment
- FIG. 4 is a graph showing a relationship between a measuring error and an angle in a case where a vibration frequency is 100 Hz, according to the first embodiment
- FIG. 5 is a graph showing a relationship between the measuring error and the angle in a case where the vibration frequency is 130 Hz, according to the first embodiment
- FIG. 6 is a cross-sectional view showing the flow measuring device according to a second embodiment of the present disclosure and corresponding to FIG. 3 in the first embodiment;
- FIG. 7 is a cross-sectional view showing the flow measuring device according to a third embodiment of the present disclosure and corresponding to FIG. 3 in the first embodiment;
- FIG. 8 is a cross-sectional view showing the flow measuring device according to a fourth embodiment of the present disclosure and corresponding to FIG. 2 in the first embodiment;
- FIG. 9 is a cross-sectional view showing the flow measuring device and taken along a IX-IX line in FIG. 8 , according to the fourth embodiment.
- FIG. 10 is a graph showing a relationship between the measuring error and the angle in a case where the vibration frequency is a first frequency, according to the fourth embodiment
- FIG. 11 is a graph showing a relationship between the measuring error and the angle in a case where the vibration frequency is a second frequency, according to the fourth embodiment.
- FIG. 12 is a cross-sectional view showing the flow measuring device according to a fifth embodiment of the present disclosure and corresponding to FIG. 3 in the first embodiment;
- FIG. 13 is a cross-sectional view showing the flow measuring device according to a modification example of the present disclosure and corresponding to FIG. 3 in the first embodiment;
- FIG. 14 is a cross-sectional view showing the flow measuring device according to another modification example of the present disclosure and corresponding to FIG. 3 in the first embodiment;
- FIG. 15 is a diagram showing an end point position, according to another modification example of the present disclosure.
- FIG. 16 is a cross-sectional view showing the flow measuring device according to another modification example of the present disclosure and corresponding to FIG. 3 in the first embodiment;
- FIG. 17 is a diagram showing the flow measuring device along the flowing direction of the intake air, according to another modification example of the present disclosure.
- FIG. 18 is a cross-sectional view showing the flow measuring device and taken along a XVIII-XVIII line in FIG. 17 .
- a part that corresponds to a matter described in a preceding embodiment may be assigned with the same reference numeral, and redundant explanation for the part may be omitted.
- another preceding embodiment may be applied to the other parts of the configuration.
- the parts may be combined even if it is not explicitly described that the parts can be combined.
- the embodiments may be partially combined even if it is not explicitly described that the embodiments can be combined, provided there is no harm in the combination.
- the flow measuring device 1 is mounted to an intake air channel 2 that is a duct through which an intake air suctioned into an internal combustion engine used in a vehicle flows.
- the flow measuring device 1 measures a flow volume of the intake air flowing through the intake air channel 2 .
- a direction where the intake air in a center part of the intake air channel 2 flows is referred to as a first flowing direction f 1 .
- the center part of the intake air channel 2 is a part of the intake air channel 2 that is located at a center region of the intake air channel 2 .
- a wall surface constituting the intake air channel 2 in the center part hardly affects a flow of the intake air.
- the flow measuring device 1 includes a housing 3 , a flow sensing chip 5 .
- the housing 3 receives the flow sensing chip 5 and protrudes inwardly in a radial direction of the intake air channel 2 through which the intake air suctioned into the internal combustion engine flows.
- the housing 3 is made of a resin material and includes a bypass passage 7 .
- the bypass passage 7 includes a sub-bypass passage 9 that branches off from the bypass passage 7 .
- the bypass passage 7 is a passage introducing a part of the intake air flowing through the intake air channel 2 and extends in a direction parallel to the first flowing direction f 1 .
- the bypass passage 7 includes a bypass inlet 7 a located uppermost stream of the bypass passage 7 and a bypass outlet 7 b located downmost stream of the bypass passage 7 .
- the bypass passage 7 further includes an outlet throttle 7 c located at a position adjacent to the bypass outlet 7 b and throttling the flow of the intake air passing the bypass passage 7 .
- the sub-bypass passage 9 is a passage introducing a part of the intake air flowing through the bypass passage 7 .
- the sub-bypass passage 9 includes a sub-bypass inlet 9 a through which the part of the intake air flowing through the bypass passage 7 flows into and a sub-bypass outlet 9 b through which the intake air flowing through the sub-bypass passage 9 is returned to the intake air channel 2 .
- the sub-bypass passage 9 rotates the intake air flowing into the sub-bypass inlet 9 a in the housing 3 and introduces the intake air to the sub-bypass outlet 9 b .
- the sub-bypass passage 9 extends from the sub-bypass inlet 9 a in a direction different from the first flowing direction f 1 .
- a foreign matter such as a dust or an oil which is included in the intake air channel 2 and enters the bypass inlet 7 a is separated to the bypass outlet 7 b , and it can be suppressed that the foreign matter enters the sub-bypass passage 9 .
- the flow sensing chip 5 includes a sensing surface portion 10 located at a surface of the flow sensing chip 5 .
- the sensing surface portion 10 senses the flow volume of the intake air.
- the sensing surface portion 10 is a planar shape.
- the sensing surface portion 10 is a heat transmission type and measures the flow volume by a heat transmission between the sensing surface portion 10 and the intake air passing the sub-bypass passage 9 .
- the sensing surface portion 10 includes a heat generation resistor and a temperature sensing resistor that are located at a surface of the sensing surface portion 10 .
- the sensing surface portion 10 generates an electrical signal is response to the flow volume of the intake air of the sub-bypass passage 9 .
- the flow sensing chip 5 outputs the electrical signal to an ECU that is not shown via a connection terminal in a connector 11 .
- the flow sensing chip 5 indirectly outputs an electrical signal in response to the flow volume of the intake air in the intake air channel 2 .
- a direction where the intake air in a center part of the sub-bypass passage 9 flows is referred to as a second flowing direction f 2 .
- the center part of the sub-bypass passage 9 is a part of the sub-bypass passage 9 that is located at a center region of the sub-bypass passage 9 .
- a wall surface of a flowing passage wall constituting the sub-bypass passage 9 in the center part hardly affects the flow of the intake air.
- the flow sensing chip 5 is supported by a support portion 13 , and the sensing surface portion 10 is exposed to the sub-bypass passage 9 . Specifically, the flow sensing chip 5 is supported by the support portion 13 such that the surface of the sensing surface portion 10 is located in a direction parallel to the second flowing direction f 2 . The sensing surface portion 10 is located on a part of the surface of the flow sensing chip 5 . According to the first embodiment, the first flowing direction f 1 is opposite to the second flowing direction f 2 .
- the sub-bypass passage 9 is throttled by a throttle portion 15 such that a cross-sectional area of the sub-bypass passage 9 perpendicular to the second flowing direction f 2 decreases in accordance with a decrease in distance from a gravity center of the sensing surface portion 10 to a center of the cross-sectional area in the direction parallel to the second flowing direction f 2 .
- the throttle portion 15 is a part of a first flowing passage wall 16 a constituting the sub-bypass passage 9 and faces the sensing surface portion 10 .
- a second flowing passage wall 16 b constituting the sub-bypass passage 9 is opposite to the first flowing passage wall 16 a .
- the flow sensing chip 5 is supported between a pair of flowing passage walls that is the first flowing passage wall 16 a and the second flowing passage wall 16 b by the support portion 13 .
- the housing 3 includes the first flowing passage wall 16 a and the second flowing passage wall 16 b.
- the throttle portion 15 throttles the cross-sectional area of the sub-bypass passage 9 such that a distance from the sensing surface portion 10 to the first flowing passage wall 16 a at the cross-sectional area in a direction perpendicular to the sensing surface portion 10 decreases in accordance with a decrease in distance from the gravity center of the sensing surface portion 10 to the center of the cross-sectional area in the direction parallel to the second flowing direction f 2 .
- the throttle portion 15 extends in the direction parallel to the second flowing direction f 2 .
- the throttle portion 15 includes a first throttle portion 15 u located upstream of the gravity center of the sensing surface portion 10 in the second flowing direction f 2 and a second throttle portion 15 d located downstream of the gravity center of the sensing surface portion 10 in the second flowing direction f 2 .
- the throttle portion 15 is a shape elongated in the direction parallel to the second flowing direction f 2 .
- a position where the first throttle portion 15 u starts is referred to as a first start point position ⁇ u
- a position of the first throttle portion 15 u where a distance between the gravity center of the sensing surface portion 10 and the first throttle portion 15 u is shortest is referred to as a first end point position ⁇ u.
- the distance is referred to as a shortest distance between the gravity center of the sensing surface portion 10 and the first throttle portion 15 u .
- the first start point position ⁇ u and the first end point position ⁇ u define a first imagination line ⁇ u.
- the first imagination line ⁇ u and the second flowing direction f 2 define a first angle ⁇ u that is in a range from 0 degrees to 20 degrees.
- the first start point position ⁇ u is located uppermost stream of the first throttle portion 15 u in the second flowing direction f 2 .
- a total distance that is a sum of a distance between the gravity center of the sensing surface portion 10 and the first flowing passage wall 16 a at the first throttle portion 15 u in the direction perpendicular to the sensing surface portion 10 and a distance between the gravity center of the sensing surface portion 10 and the first flowing passage wall 16 a at the first throttle portion 15 u in the direction parallel to the second flowing direction f 2 becomes shortest.
- the total distance is equivalent to the shortest distance between the gravity center of the sensing surface portion 10 and the first throttle portion 15 u.
- the first start point position ⁇ u is a position where a distance between the first start point position ⁇ u and the first end point position ⁇ u is shortest.
- the distance is referred to as a shortest distance between the first start point position ⁇ u and the first end point position ⁇ u.
- a total distance that is a sum of a distance between the first start point position ⁇ m and the first end point position ⁇ u in the direction perpendicular to the sensing surface portion 10 and a distance between the first start point position ⁇ m and the first end point position ⁇ u in the direction parallel to the second flowing direction f 2 becomes shortest.
- the total distance is equivalent to the shortest distance between the first start point position ⁇ u and the first end point position ⁇ u.
- the first throttle portion 15 u and the second throttle portion 15 d have surfaces that are curved surfaces protruding inwardly in a radial direction of the sub-bypass passage 9 .
- the throttle portion 15 including the first throttle portion 15 u and the second throttle portion 15 d includes a side surface facing the sensing surface portion 10 .
- the side surface is also a side surface of a cylinder having an axis extending in a height direction that is perpendicular to the second flowing direction f 2 and is parallel to the sensing surface portion 10 .
- the first throttle portion 15 u throttles the cross-sectional area of the sub-bypass passage 9 such that the distance from the sensing surface portion 10 to the first flowing passage wall 16 a at the cross-sectional area in the direction perpendicular to the sensing surface portion 10 decreases in accordance with a decrease in distance from the gravity center of the sensing surface portion 10 to the center of the cross-sectional area in the direction parallel to the second flowing direction f 2 .
- the first start point position ⁇ m is a position where the first throttle portion 15 u starts and the first end point position ⁇ u is the position of the first throttle portion 15 u where the distance between the gravity center of the sensing surface portion 10 and the first throttle portion 15 u is shortest
- the first angle ⁇ u defined by the first imagination line ⁇ u and the second flowing direction f 2 is in a range from 0 degrees to 20 degrees.
- the first flowing passage wall 16 a gradually varies in the first throttle portion 15 u , it can be suppressed that a vortex or a separation is generated in the flow of the intake air in the vicinity of the first throttle portion 15 u . Further, a disturb of the flow of the intake air generated by the first throttle portion 15 u at the sensing surface portion 10 can be suppressed. Furthermore, in the flow measuring device 1 including the first throttle portion 15 u , a sensing accuracy of the flow volume at the sensing surface portion 10 can be improved.
- the surface of the first throttle portion 15 u is a curved surface protruding inwardly in the radial direction of the sub-bypass passage 9 .
- a variation relative to a flowing direction of the surface of the first throttle portion 15 u can be maintained to be smooth, and the cross-sectional area of the sub-bypass passage 9 perpendicular to the second flowing direction f 2 can be decreased. Further, it can be suppressed that the vortex or the separation is generated in the flow of the intake air in the vicinity of the first throttle portion 15 u , and it can be reduced that a pressure loss is generated in the sub-bypass passage 9 .
- the first throttle portion 15 u and the second throttle portion 15 d are located upstream and downstream of the sensing surface portion 10 in the second flowing direction f 2 , respectively. Since the second throttle portion 15 d is located downstream of the sensing surface portion 10 in the second flowing direction f 2 , the flow measuring device 1 can properly measure the flow volume in a case where a pulse flow is generated in response to an operation of a piston of the internal combustion engine. In other words, when a flow of a gas flowing from downstream to upstream, a flow rate at the sensing surface portion 10 can be ensured, and the flow measuring device 1 can properly measure the flow volume.
- FIGS. 4 and 5 are graphs plotting measuring errors of when the first angle ⁇ u is changed.
- the measuring error when a vibration frequency of the flow volume is low, the measuring error is relatively small without respect to a value of the first angle ⁇ u, and the flow measuring device 1 has a characteristic that changes in response to a change of the flow volume. In the change of the flow volume, the flow volume increases or decreases.
- the vibration frequency of the flow volume when the vibration frequency of the flow volume is high, the measuring error increases in a case where the first angle ⁇ u exceeds 20 degrees, and the characteristic is deteriorated.
- the first throttle portion 15 u includes a surface 17 u that is a planar surface. Further, according to the present embodiment, the second throttle portion 15 d is cancelled. Thus, according to the present embodiment, the first throttle portion 15 u is referred to as a throttle portion 15 u.
- FIG. 6 indicates a start point position ⁇ u, an end point position ⁇ u, an imagination line ⁇ u and an angle ⁇ u that are equivalent to the first start point position ⁇ u, the first end point position ⁇ u, the first imagination line ⁇ u and the first angle ⁇ u of the first embodiment.
- the start point position ⁇ u is located upstream of the sensing surface portion 10 that is a sensing portion 18 in a flowing direction f 2 that is equivalent to the second flowing direction f 2 of the first embodiment.
- the surface 17 u of the throttle portion 15 u and the flowing direction f 2 define an angle that is equal to the angle ⁇ u.
- a variation relative to a flowing direction of the surface of the throttle portion 15 u can be maintained to be smooth, the cross-sectional area of the sub-bypass passage 9 perpendicular to the flowing direction f 2 can be decreased at the sensing portion 18 , and the flow rate at the sensing portion 18 can be ensured. Since the cross-sectional area gradually varies, a variation amount of the flow rate generated by the throttle portion 15 u in the vicinity of the surface 17 u is small, it can be suppressed that a vortex is generated.
- the surface 17 u is a planar surface, it is difficult that a flow rate variation in a direction perpendicular to a flow flowing in a direction along the surface 17 u is generated, and it can be suppressed that the separation is generated. In addition, since the surface 17 u is a planar surface, the surface 17 u is readily to be formed.
- a second throttle portion 20 that is different from the first throttle portion 15 u is located on the second flowing passage wall 16 b . Since at least two throttle portions are provided in the sub-bypass passage 9 , the cross-sectional area of the sub-bypass passage 9 can be further decreased when the angle ⁇ u is maintained to be smaller than 20 degrees. Then, the flow rate of the intake air at the sensing surface portion 10 can be further increased, and a heat transmission performance and the sensing accuracy can be further stabilized.
- the measuring error increases.
- the vibration frequency of the flow volume is high and the first angle ⁇ u exceeds 20 degrees.
- the vibration frequency of the flow volume is high and the first angle ⁇ u is 30 degrees, the measuring error is still relatively small.
- components of the flow measuring device 1 that are different from that according to the first embodiment will be described.
- a part of the bypass passage 7 from the bypass inlet 7 a to the bypass outlet 7 b is referred to as a passing passage 8 .
- the passing passage 8 includes an upstream end portion where the bypass inlet 7 a is located and a downstream end portion where the bypass outlet 7 b is located.
- the passing passage 8 extends in the direction parallel to the first flowing direction f 1 of the intake air channel 2 .
- the sub-bypass passage 9 can be referred to as a branch passage that branches off from an intermediate part of the passing passage 8 .
- the first throttle portion 15 u includes an inner peripheral surface straightly extending from the first start point position ⁇ u to the first end point position ⁇ d
- the second throttle portion 15 d includes an inner peripheral surface straightly extending from the second start point position ⁇ u to the second end point position ⁇ d.
- the inner peripheral surface of the first throttle portion 15 u is equivalent to a surface of the first throttle portion 15 u according to the first embodiment.
- the first throttle portion 15 u and the second throttle portion 15 d include inner peripheral surfaces that may be have a part that is recessed or protruded or curved, respectively.
- the first angle ⁇ u and the second angle ⁇ d are equal to 30 degrees.
- the first throttle portion 15 u is equivalent to an upstream throttle portion.
- the sensing surface portion 10 is referred to as a sensing portion.
- a pair of flowing passage walls including the first flowing passage wall 16 a and the second flowing passage wall 16 b is arranged in an arrangement direction that is referred to as a width direction X.
- the first flowing passage wall 16 a includes the first throttle portion 15 u and the second throttle portion 15 d
- the second flowing passage wall 16 b excludes the first throttle portion 15 u and the second throttle portion 15 d .
- the width direction X is an orthogonal direction that is perpendicular to the second flowing direction f 2 .
- the support portion 13 is made of a synthetic resin material and is a plate shape. The support portion 13 divides the sub-bypass passage 9 into two regions in the width direction.
- the support portion 13 is located to be parallel to the first flowing passage wall 16 a and the second flowing passage wall 16 b and extends in the direction parallel to the second flowing direction f 2 .
- the support portion 13 is also located to be parallel to a direction in which the first start point position ⁇ m and the second start point position ⁇ d are arranged.
- the support portion 13 includes a first opposite surface 13 a facing the first flowing passage wall 16 a and a second opposite surface 13 b facing the second flowing passage wall 16 b .
- the flow sensing chip 5 and the sensing surface portion 10 are located on the first opposite surface 13 a.
- the support portion 13 has a support length L 1 that is a length of the support portion 13 in the direction parallel to the second flowing direction f 2 that is equal to a throttle length La that is a total length of the first throttle portion 15 u and the second throttle portion 15 d in the direction parallel to the second flowing direction f 2 .
- the flow sensing chip 5 and the sensing surface portion 10 are located at a center of the support portion 13 in the direction parallel to the second flowing direction f 2 . In other words, the flow sensing chip 5 and the sensing surface portion 10 are located such that center lines of the flow sensing chip 5 and the sensing surface portion 10 that are parallel to the width direction X match a center line C of the support portion 13 that is perpendicular to the second flowing direction f 2 .
- a first support distance L 2 that is a distance from an upstream end of the support portion 13 to the center line C is equal to a second support distance L 3 that is a distance from the center line C to a downstream end of the support portion 13 .
- the upstream end of the support portion 13 and the first start point position ⁇ u define a distance that is referred to as an upstream shift distance L 5 .
- the downstream end of the support portion 13 and the second start point position ⁇ d define a distance that is referred to as a downstream shift distance L 6 . Since the support length L 1 of the support portion 13 is equal to the throttle length La of the first throttle portion 15 u and the second throttle portion 15 d , the center shift distance L 4 , the upstream shift distance L 5 and the downstream shift distance L 6 are equal to each other.
- the throttle length La is also a distance from the first start point position ⁇ u to the second start point position ⁇ d.
- the first throttle portion 15 u located upstream of the gravity center of the sensing surface portion 10 has a length in the direction parallel to the second flowing direction f 2 that is referred to as a first throttle length Lb and is equal to a length of the second throttle portion 15 d located downstream of the gravity center of the sensing surface portion 10 in the direction parallel to the second flowing direction f 2 that is referred to as a second throttle length Lc.
- the throttle length La is a sum of the first throttle length Lb and the second throttle length Lc.
- the first angle ⁇ u is equal to the second angle ⁇ d
- the first end point position ⁇ u and the second end point position ⁇ d are located at a center between the first start point position ⁇ u and the second start point position ⁇ d.
- the sensing surface portion 10 is located between the first start point position ⁇ u and the first end point position ⁇ u or between the first start point position ⁇ u and the second end point position ⁇ d in the direction parallel to the second flowing direction f 2 .
- the sensing surface portion 10 is located at a position close to the first end point position ⁇ u and the second end point position ⁇ d, and the sensing surface portion 10 does not protrude to a position downstream of the first end point position ⁇ d and the second end point position ⁇ d in the second flowing direction f 2 .
- the sensing surface portion 10 is located to be close to the first end point position ⁇ u and the second end point position ⁇ d such that the flow sensing chip 5 protrudes to a position downstream of the first end point position ⁇ u and the second end point position ⁇ d in the second flowing direction f 2 .
- a half of a sensing length L 7 that is a length of the sensing surface portion 10 in the direction parallel to the second flowing direction f 2 is shorter than the center shift distance L 4 .
- a center part of the sensing surface portion 10 is located upstream of the first end point position ⁇ u and the second end point position Pd.
- the support portion 13 is located at a position where the first flowing passage wall 16 a is closer to the support portion 13 than the second flowing passage wall 16 b is in the width direction X.
- a first facing distance B 1 that is a distance from the first start point position ⁇ u and the second start point position ⁇ d to the support portion 13 in the width direction X is shorter than a second facing distance B 2 that is a distance from the support portion 13 to the second flowing passage wall 16 b in the width direction X.
- a gap distance B 3 that is a distance from the first end point position ⁇ u and the second end point position ⁇ d to the support portion 13 in the width direction X is shorter than a throttle distance B 4 that is a distance from the first start point position ⁇ m and the second start point position ⁇ d to the first end point position ⁇ u and the second end point position ⁇ d in the width direction X.
- the first facing distance B 1 is a sum of the gap distance B 3 and the throttle distance B 4 .
- the gap distance B 3 is longer than a thickness of the support portion 13 and a thickness of the flow sensing chip 5 .
- a space between the first flowing passage wall 16 a and the support portion 13 is referred to as a first region 21 a where the sensing surface portion 10 is located, and a space between the support portion 13 and the second flowing passage wall 16 b is referred to as a second region 21 b .
- the first region 21 a is equivalent to a sensing region
- the second region 21 b is equivalent to an opposite region.
- the support portion 13 is located between the sensing surface portion 10 and the second region 21 b .
- a width of the first region 21 a in the width direction X gradually decreases from the first start point position ⁇ u to the first end point position ⁇ u in the second flowing direction f 2 and gradually increases from the second end point position ⁇ d to the second start point position ⁇ d in the second flowing direction f 2 .
- the first flowing passage wall 16 a further includes an upstream wall surface 22 a that is a wall surface located upstream of the first start point position ⁇ u and a downstream wall surface 22 b that is a wall surface located downstream of the second start point position ad.
- the first region 21 a is also defined by the upstream wall surface 22 a and the support portion 13 .
- the upstream wall surface 22 a and the downstream wall surface 22 b are in contact with the first start point position ⁇ u and the second start point position ⁇ d, respectively.
- a distance from the upstream wall surface 22 a and the downstream wall surface 22 b to the support portion 13 in the width direction X is equal to the first facing distance B 1 .
- the first angle ⁇ u is equal to a slope angle of the inner peripheral surface of the first throttle portion 15 u relative to the upstream wall surface 22 a and the second angle ⁇ d is equal to a slope angle of the inner peripheral surface of the second throttle portion 15 d relative to the downstream wall surface 22 b.
- the intake air flowing into a position upstream of the support portion 13 in the sub-bypass passage 9 is divided into two parts that are a first intake air flowing into the first region 21 a and a second intake air flowing into the second region 21 b . Since the width of the second region 21 b is greater than the width of the first region 21 a , the foreign matter included in the intake air flows into the second region 21 b more readily than the first region 21 a . In other words, a configuration that the foreign matter is difficult to flow into the first region 21 a is achieved. Thus, it can be suppressed that the sensing accuracy of the sensing surface portion 10 is deteriorated or the sensing surface portion 10 is damaged due to the foreign matter approaching or being in contact with the sensing surface portion 10 .
- a width of an upstream end part of the first region 21 a is equal to the first facing distance B 1 .
- the width of the upstream end part of the first region 21 a is greater than that in a configuration where the first throttle portion 15 u extends to a position upstream of the support portion 13 .
- a throttle rate is a ratio of the upstream end part of the first region 21 a to a downstream end part of the first region 21 a .
- the width of the upstream end part becomes greater, it is likely that the throttle rate becomes greater and the flow rate of the first intake air reached the downstream end part of the first region 21 a becomes greater.
- the flow rate of the first intake air flowing into the first region 21 a is gradually increased while the first intake air is throttled between the support portion 13 and the first throttle portion 15 u after the first intake air is straightened between the support portion 13 and the upstream wall surface 22 a .
- a part of the first region 21 a between the support portion 13 and the upstream wall surface 22 a functions as a straightening region that straightens the first intake air, it is difficult that the disturb that is the vortex or the separation is generated in the first intake air in the first region 21 a between the support portion 13 and the first throttle portion 15 u .
- the sensing surface portion 10 senses the flow volume based on a temperature change generated according to the flow volume of the first intake air. Thus, when the temperature change is generated due to the disturb of the flow applied to the sensing surface portion 10 , the sensing accuracy of the flow volume by using the sensing surface portion 10 is deteriorated.
- the disturb that is the vortex or the separation is readily generated in the first intake air passing through the first end point position ⁇ u and the second end point position ⁇ d in the first region 21 a .
- the disturb is generated at a position immediately downstream of the first end point position ⁇ u and the second end point position ⁇ d due to a part of the first intake air flowing along the second throttle portion 15 d and a part of the first intake air flowing toward the support portion 13 .
- the sensing surface portion 10 Since the sensing surface portion 10 is located upstream of the first end point position ⁇ u and the second end point position ⁇ d, it is difficult that the disturb generated at a position downstream of the first end point position ⁇ u and the second end point position ⁇ d affects the first intake air between the sensing surface portion 10 and the first throttle portion 15 u . Thus, it is difficult that the sensing accuracy of the sensing surface portion 10 is deteriorated due to the disturb generated in the first intake air downstream of the first end point position ⁇ u and the second end point position ⁇ d.
- the unit of the measuring error is %.
- the sensing surface portion 10 is located in the sub-bypass passage 9 in the bypass passage 7 without being located in the passing passage 8 in the bypass passage 7 , the measuring error is readily increased in a case where the disturb generated when the intake air flows from the passing passage 8 into the sub-bypass passage 9 reaches the first region 21 a.
- the measuring error when the vibration frequency is a first frequency that is relatively low, the measuring error is in an allowable range in a case where the first angle ⁇ u is larger than 20 degrees.
- a measuring result of the flow measuring device 1 indicates a characteristic that changes in response to a change of the intake air in the intake air channel 2 .
- the first angle ⁇ u when the first angle ⁇ u is up to 30 degrees or 40 degrees, the measuring error is still in the allowable range.
- the first frequency may be 100 Hz, and the allowable range of the measuring error may be less than or equal to 3%.
- the vibration frequency is a second frequency that is relative high
- the measuring error is sharply increased to be out of the allowable range in a case where the first angle ⁇ u exceeds 20 degrees.
- the measuring error is still in the allowable range in a case where the first angle ⁇ u exceeds 20 degrees and is up to a value slightly exceeding 30 degrees, and the measuring error is sharply increased to be out of the allowable range in a case where the first angle ⁇ u exceeds the value slightly exceeding 30 degrees.
- the measuring error of the flow measuring device 1 can be reduced more than that in a case where the first angle ⁇ u and the second angle ⁇ d are set to be larger than 30 degrees.
- the sensing surface portion 10 is located between the first start point position ⁇ u and the first end point position ⁇ u, it is difficult that the disturb generated in the flow downstream of the first end point position ⁇ u is applied to the sensing surface portion 10 .
- the sensing accuracy of the sensing surface portion 10 is deteriorated due to the disturb generated in the flow downstream of the first end point position ⁇ u.
- the sensing surface portion 10 is located at a position be close to the first end point position ⁇ u and the second end point position ⁇ d where the flow rate of the first intake air is readily increased in the first region 21 a , the flow rate of the first intake air applied to the sensing surface portion 10 is readily increased.
- the sensing accuracy of the sensing surface portion 10 can be improved.
- the support portion 13 extends to a position upstream of the first start point position ⁇ u.
- the first intake air flowing into the first region 21 a flows between the support portion 13 and the upstream wall surface 22 a to be straightened before the first intake air reaches the first throttle portion 15 u .
- the gap distance B 3 is shorter than the throttle distance B 4 .
- the sensing accuracy of the sensing surface portion 10 can be improved.
- the first end point position ⁇ u matches the second end point position ⁇ d.
- the first end point position ⁇ u and the second end point position ⁇ d are separated from each other in the direction parallel to the second flowing direction f 2 . According to the present embodiment, components of the flow measuring device 1 that are different from that according to the fourth embodiment will be described.
- a connection portion 23 that is connected with the first throttle portion 15 u and the second throttle portion 15 d is located between the first throttle portion 15 u and the second throttle portion 15 d .
- the connection portion 23 includes an inner peripheral surface extending in a direction parallel to the upstream wall surface 22 a and the downstream wall surface 22 b .
- the connection portion 23 has a connection length Ld that is a length of the connection portion in the direction parallel to the second flowing direction f 2 .
- the connection length Ld is also a distance from the first end point position ⁇ u to the second end point position ⁇ d.
- the gap distance B 3 is equal to the throttle distance B 4 .
- the gap distance B 3 may be longer than the throttle distance B 4 .
- the width of the first region 21 a in the width direction X gradually decreases in accordance with a decrease in distance between a position of the first opposite surface 13 a at a cross-sectional area including the width and the gravity center of the sensing surface portion 10 in the direction parallel to the second flowing direction f 2 , the flow rate of the first intake air flowing between the connection portion 23 and the support portion 13 can be properly increased.
- the first throttle portion 15 u and the second throttle portion 15 d have surfaces that are curved surfaces.
- the first throttle portion 15 u and the second throttle portion 15 d have surfaces that are planar surfaces.
- a space of the sub-bypass passage 9 between the first throttle portion 15 u and the second throttle portion 15 d in the direction parallel to the second flowing direction f 2 is a constant region where the cross-sectional area of the sub-bypass passage 9 perpendicular to the second flowing direction f 2 is minimum and is constant.
- the sensing surface portion 10 is located in the constant region.
- the cross-sectional area of the sub-bypass passage 9 perpendicular to the second flowing direction f 2 becomes minimum at the sensing surface portion 10 .
- the cross-sectional area of the sub-bypass passage 9 perpendicular to the second flowing direction f 2 is minimum at a position downstream of the sensing surface portion 10 .
- a third distance d 3 is a distance obtained by subtracting the first distance d 1 from a distance between the second position p 2 and the sensing surface portion 10 in the direction perpendicular to the surface of the sensing surface portion 10 and the second flowing direction f 2 .
- a length of the second line L 2 is equal to the distance between the second position p 2 and the sensing surface portion 10 in the direction perpendicular to the surface of the sensing surface portion 10 and the second flowing direction f 2 .
- a distance between the second position p 2 and the sensing surface portion 10 is equal to a sum of the first distance d 1 and the third distance d 3 (d 1 +d 3 ).
- a total distance that is a sum of a distance between the gravity center of the sensing surface portion 10 and the first flowing passage wall 16 a at the first throttle portion 15 u in the direction perpendicular to the sensing surface portion 10 and a distance between the gravity center of the sensing surface portion 10 and the first flowing passage wall 16 a at the first throttle portion 15 u in the direction parallel to the second flowing direction f 2 becomes shortest.
- the total distance is equivalent to the shortest distance between the gravity center of the sensing surface portion 10 and the first throttle portion 15 u.
- the first start point position ⁇ u is a position where a distance between the first start point position ⁇ u and the first end point position ⁇ u is shortest.
- the distance is referred to as a shortest distance between the first start point position ⁇ u and the first end point position ⁇ u.
- a total distance that is a sum of a distance between the first start point position cm and the first end point position ⁇ u in the direction perpendicular to the sensing surface portion 10 and a distance between the first start point position cm and the first end point position ⁇ u in the direction parallel to the second flowing direction f 2 becomes shortest.
- the total distance is equivalent to the shortest distance between the first start point position ⁇ u and the first end point position ⁇ u.
- the second throttle portion 20 is located on the second flowing passage wall 16 b facing the first flowing passage wall 16 a .
- the second throttle portion 20 is located on a flowing passage wall other than the second flowing passage wall 16 b . Since the vortex slightly affects the sensing surface portion 10 when a flowing passage wall is separated from the sensing surface portion 10 by a predetermined distance, the second throttle portion 20 can be located on the first flowing passage wall 16 a.
- the housing 3 includes the sub-bypass passage 9 that is a part of the bypass passage 7 .
- the housing 3 excludes the sub-bypass passage 9 .
- an entire of the flow sensing chip 5 is located upstream of the first end point position ⁇ u and the second end point position ⁇ d.
- the sensing surface portion 10 can be located at a position close to the first end point position ⁇ u and the second end point position ⁇ d in the direction parallel to the second flowing direction f 2 .
- At least a part of the sensing surface portion 10 is located upstream of the first end point position ⁇ u.
- an entire of the sensing surface portion 10 is located upstream of the first end point position ⁇ u.
- the sensing surface portion 10 does not face the connection portion 23 , and the sensing surface portion 10 faces the first throttle portion 15 u as the same as that according to the fourth embodiment.
- the support portion 13 is not located upstream of the first start point position ⁇ u.
- the measuring error is not sharply increased until the first angle ⁇ u or the second angle ⁇ d exceeds 30 degrees.
- the first facing distance B 1 is shorter than the second facing distance B 2 .
- the support portion 13 is not located at a position where the first flowing passage wall 16 a is closer to the support portion 13 than other flowing passage walls are in the width direction X.
- the measuring error is not sharply increased until the first angle ⁇ u or the second angle ⁇ d exceeds 30 degrees.
- the flow measuring device includes a housing including a bypass passage that introduces a part of an air flowing through a duct, and a flow sensing chip located in the bypass passage and including a sensing portion that generates an electrical signal in response to a flow volume of the air in the duct.
- the bypass passage is throttled by a throttle portion such that a cross-sectional area of the bypass passage perpendicular to a flowing direction in which the air flows through the bypass passage decreases in accordance with a decrease in distance from a gravity center of the sensing surface portion to a center of the cross-sectional area in a direction parallel to the flowing direction.
- the throttle portion is a part of a flowing passage wall facing the sensing surface portion.
Abstract
A flow measuring device includes a housing including a bypass passage and a flow sensing chip located in the bypass passage and including a sensing surface portion. A throttle portion that is a part of a flowing passage wall facing a sensing surface portion throttles a cross-sectional area of a bypass passage. A position where the throttle portion starts is referred to as a start point position, and a position of the throttle portion where a distance between a gravity center of the sensing surface portion and the throttle portion is shortest is referred to as an end point position. The start point position and the end point position define an imagination line, and the imagination line and the flowing direction define an angle that is in a range from 0 degrees to 20 degrees.
Description
- This application is a divisional application of application Ser. No. 15/665,721, filed on Aug. 1, 2017 which is based on Japanese Patent Application No. 2016-152808 filed on Aug. 3, 2016 and Japanese Patent Application No. 2017-135655 filed on Jul. 11, 2017, the disclosures of each of which are incorporated herein by reference.
- The present disclosure relates to a flow measuring device that measures a flow volume of an intake air suctioned into an internal combustion engine used in a vehicle.
- Conventionally, according to JP2014-001954A, it is known that a flowing measuring device includes a housing and a flow sensing chip. The housing includes a bypass passage introducing a part of an air flowing through an intake air channel of an internal combustion engine. The flow sensing chip is located in the bypass passage and includes a sensing surface portion generating an electrical signal in response to a flow volume of the air in the intake air channel by a heat transmission between the sensing surface portion and the air flowing through the bypass passage.
- The sensing surface portion is located in a direction parallel to a flowing direction of a flow of the air flowing through the bypass passage. The bypass passage is throttled by a throttle portion such that a cross-sectional area of the bypass passage perpendicular to the flowing direction decreases in accordance with a decrease in distance from a gravity center of the sensing surface portion to a center of the cross-sectional area in the direction parallel to the flowing direction.
- Thus, when the flow volume of the air in the intake air channel is relatively small, a flow rate the air at the sensing surface portion can be sufficiently ensured, a heat transmission performance and a sensing accuracy of the flow volume can be ensured. However, when a flowing passage wall changes at the throttle portion at a sharp angle, a vortex or a separation is generated in the flow of the air in the vicinity of the throttle portion, and the flow of the air is disturbed to cancel a straightening function.
- When the vortex is generated in the vicinity of the throttle portion, a flow of the air flowing in a reverse direction that is opposite to the flowing direction is generated. In this case, a pressure loss is generated in the bypass passage, and the flow volume at the sensing surface portion is decreased. Further, when the vortex is generated in the vicinity of the throttle portion in a case where the throttle portion is close to the sensing surface portion and a pulse flow is generated in response to an operation of a piston of the internal combustion engine, the vortex reaches the sensing surface portion to lead to a sensing error.
- It is an object of the present disclosure to provide a flow measuring device which includes a throttle portion and a sensing surface portion and improves a sensing accuracy of a flow volume at the sensing surface portion.
- According to a first aspect of the present disclosure, the flowing measuring device includes a housing and a flow sensing chip. The housing includes a bypass passage that introduces a part of an air flowing through a duct. The flow sensing chip is located in the bypass passage and includes a sensing surface portion that generates an electrical signal in response to a flow volume of the air in the duct by a heat transmission between the sensing surface portion and the air flowing through the bypass passage.
- The sensing surface portion is located along a flowing direction in which the air flows through the bypass passage. The bypass passage is throttled by a throttle portion such that a cross-sectional area of the bypass passage perpendicular to the flowing direction decreases in accordance with a decrease in distance from a gravity center of the sensing surface portion to a center of the cross-sectional area in a direction parallel to the flowing direction.
- The throttle portion is a part of a flowing passage wall facing the sensing surface portion. The throttle portion throttles the cross-sectional area of the bypass passage such that a distance from the sensing surface portion to the flowing passage wall at the cross-sectional area in a direction perpendicular to the sensing surface portion decreases in accordance with a decrease in distance from the gravity center of the sensing surface portion to the center of the cross-sectional area in the direction parallel to the flowing direction. A position where the throttle portion starts is referred to as a start point position, and a position of the throttle portion where a distance between the gravity center of the sensing surface portion and the throttle portion is shortest is referred to as an end point position, the start point position and the end point position define an imagination line, and the imagination line and the flowing direction define an angle that is in a range from 0 degrees to 20 degrees.
- Thus, since the flowing passage wall gradually varies in the throttle portion, it can be suppressed that a vortex or a separation is generated in the flow of the air in the vicinity of the throttle portion. Further, a disturb of the flow of the intake air generated by the throttle portion at the sensing surface portion can be suppressed. Furthermore, in the flow measuring device including the throttle portion, a sensing accuracy of the flow volume at the sensing surface portion can be improved.
- According to a second aspect of the present disclosure, the flowing measuring device includes a housing and a flow sensing chip. The housing includes a bypass passage that introduces a part of an air flowing through a duct. The flow sensing chip is located in the bypass passage and includes a sensing portion that generates an electrical signal in response to a flow volume of the air in the duct. The bypass passage is throttled by a throttle portion such that a cross-sectional area of the bypass passage perpendicular to a flowing direction in which the air flows through the bypass passage decreases in accordance with a decrease in distance from a gravity center of the sensing surface portion to a center of the cross-sectional area in a direction parallel to the flowing direction.
- The throttle portion is a part of a flowing passage wall facing the sensing surface portion. A position where the throttle portion starts is referred to as a start point position, and the start point position is located upstream of the sensing portion in the flowing direction. The throttle portion includes a surface that is a planar surface. The surface of the throttle portion and the flowing direction define an angle that is in a range from 0 degrees to 20 degrees.
- Thus, similar to the first aspect, a disturb of the flow of the intake air generated by the throttle portion at the sensing surface portion can be suppressed. Further, in the flow measuring device including the throttle portion, a sensing accuracy of the flow volume at the sensing surface portion can be improved. In addition, the sensing portion may be a shape other than a planar shape.
- According to a third aspect of the present disclosure, the flow measuring device includes a housing including a bypass passage that introduces a part of an air flowing through a duct, and a flow sensing chip located in the bypass passage and including a sensing surface portion that generates an electrical signal in response to a flow volume of the air in the duct by a heat transmission between the sensing surface portion and the air flowing through the bypass passage. The sensing surface portion is located along a flowing direction in which the air flows through the bypass passage. The bypass passage is throttled by a throttle portion such that a cross-sectional area of the bypass passage perpendicular to the flowing direction decreases in accordance with a decrease in distance from a gravity center of the sensing surface portion to a center of the cross-sectional area in a direction parallel to the flowing direction. The throttle portion is a part of a flowing passage wall that is included in the housing and faces the sensing surface portion, the throttle portion throttles the cross-sectional area of the bypass passage such that a distance from the sensing surface portion to the flowing passage wall at the cross-sectional area in a direction perpendicular to the sensing surface portion decreases in accordance with a decrease in distance from the gravity center of the sensing surface portion to the center of the cross-sectional area in the direction parallel to the flowing direction. A position where the throttle portion starts is referred to as a start point position, and a position of the throttle portion where a distance between the gravity center of the sensing surface portion and the throttle portion is shortest is referred to as an end point position. The start point position and the end point position define an imagination line, and the imagination line and the flowing direction define an angle that is in a range from 0 degrees to 30 degrees.
- Thus, effects the same as that is the first aspect can be achieved.
- According to a fourth aspect of the present disclosure, the flow measuring device includes a housing including a bypass passage that introduces a part of an air flowing through a duct, and a flow sensing chip located in the bypass passage and including a sensing portion that generates an electrical signal in response to a flow volume of the air in the duct. The bypass passage is throttled by a throttle portion such that a cross-sectional area of the bypass passage perpendicular to a flowing direction in which the air flows through the bypass passage decreases in accordance with a decrease in distance from a gravity center of the sensing surface portion to a center of the cross-sectional area in a direction parallel to the flowing direction. The throttle portion is a part of a flowing passage wall facing the sensing surface portion. A position where the throttle portion starts is referred to as a start point position, the start point position is located upstream of the sensing portion in the flowing direction. The throttle portion includes a surface that is a planar surface, the surface of the throttle portion and the flowing direction define an angle that is in a range from 0 degrees to 30 degrees.
- Thus, effects the same as that is the first aspect can be achieved.
- According to a fifth aspect of the present disclosure, the flow measuring device measures a flow volume of an air. The flow measuring device includes a bypass passage through which the air flows, a sensing portion outputting an electrical signal in response to the flow volume of the air in the bypass passage, a pair of flowing passage walls facing each other, the sensing portion located between the flowing passage walls, and a throttle portion throttling the bypass passage by protruding from the flowing passage walls toward the sensing portion, in an arrangement direction in which the pair of the flowing passage walls is arranged. The throttle portion has a protruding dimension gradually increases in accordance with a decrease in distance from the throttle portion to the sensing portion from an upstream end of the throttle portion in the bypass passage in a flowing direction in which the air flows through the bypass passage. A position of an upstream end of the throttle portion is referred to as a start point position, and a position of the throttle portion where a distance between the gravity center of the sensing surface portion and the throttle portion is shortest is referred to as an end point position. The start point position and the end point position define an imagination line, and the imagination line and the flowing direction define an angle that is in a range from 0 degrees to 30 degrees.
- Thus, effects the same as that is the first aspect can be achieved.
- The above and other objects, features and advantages of the present disclosure will become more apparent from the following detailed description made with reference to the accompanying drawings. In the drawings:
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FIG. 1 is a diagram showing an outline of a flow measuring device viewed from an upstream of an intake air flow, according to a first embodiment of the present disclosure; -
FIG. 2 is a cross-sectional view showing the flow measuring device along a flowing direction of an intake air, according to the first embodiment; -
FIG. 3 is a cross-sectional view showing the flow measuring device and taken along a line inFIG. 2 , according to the first embodiment; -
FIG. 4 is a graph showing a relationship between a measuring error and an angle in a case where a vibration frequency is 100 Hz, according to the first embodiment; -
FIG. 5 is a graph showing a relationship between the measuring error and the angle in a case where the vibration frequency is 130 Hz, according to the first embodiment; -
FIG. 6 is a cross-sectional view showing the flow measuring device according to a second embodiment of the present disclosure and corresponding toFIG. 3 in the first embodiment; -
FIG. 7 is a cross-sectional view showing the flow measuring device according to a third embodiment of the present disclosure and corresponding toFIG. 3 in the first embodiment; -
FIG. 8 is a cross-sectional view showing the flow measuring device according to a fourth embodiment of the present disclosure and corresponding toFIG. 2 in the first embodiment; -
FIG. 9 is a cross-sectional view showing the flow measuring device and taken along a IX-IX line inFIG. 8 , according to the fourth embodiment; -
FIG. 10 is a graph showing a relationship between the measuring error and the angle in a case where the vibration frequency is a first frequency, according to the fourth embodiment; -
FIG. 11 is a graph showing a relationship between the measuring error and the angle in a case where the vibration frequency is a second frequency, according to the fourth embodiment; -
FIG. 12 is a cross-sectional view showing the flow measuring device according to a fifth embodiment of the present disclosure and corresponding toFIG. 3 in the first embodiment; -
FIG. 13 is a cross-sectional view showing the flow measuring device according to a modification example of the present disclosure and corresponding toFIG. 3 in the first embodiment; -
FIG. 14 is a cross-sectional view showing the flow measuring device according to another modification example of the present disclosure and corresponding toFIG. 3 in the first embodiment; -
FIG. 15 is a diagram showing an end point position, according to another modification example of the present disclosure; -
FIG. 16 is a cross-sectional view showing the flow measuring device according to another modification example of the present disclosure and corresponding toFIG. 3 in the first embodiment; -
FIG. 17 is a diagram showing the flow measuring device along the flowing direction of the intake air, according to another modification example of the present disclosure; and -
FIG. 18 is a cross-sectional view showing the flow measuring device and taken along a XVIII-XVIII line inFIG. 17 . - In the embodiments, a part that corresponds to a matter described in a preceding embodiment may be assigned with the same reference numeral, and redundant explanation for the part may be omitted. When only a part of a configuration is described in an embodiment, another preceding embodiment may be applied to the other parts of the configuration. The parts may be combined even if it is not explicitly described that the parts can be combined. The embodiments may be partially combined even if it is not explicitly described that the embodiments can be combined, provided there is no harm in the combination.
- Hereafter, embodiments of the present disclosure will be described. In addition, the present disclosure is not limited to the embodiments that are examples of the present disclosure.
- Referring to
FIGS. 1 and 2 , aflow measuring device 1 according to a first embodiment of the present disclosure will be described. Theflow measuring device 1 is mounted to anintake air channel 2 that is a duct through which an intake air suctioned into an internal combustion engine used in a vehicle flows. Theflow measuring device 1 measures a flow volume of the intake air flowing through theintake air channel 2. According to the present embodiment, a direction where the intake air in a center part of theintake air channel 2 flows is referred to as a first flowing direction f1. The center part of theintake air channel 2 is a part of theintake air channel 2 that is located at a center region of theintake air channel 2. A wall surface constituting theintake air channel 2 in the center part hardly affects a flow of the intake air. Theflow measuring device 1 includes ahousing 3, aflow sensing chip 5. - The
housing 3 receives theflow sensing chip 5 and protrudes inwardly in a radial direction of theintake air channel 2 through which the intake air suctioned into the internal combustion engine flows. Thehousing 3 is made of a resin material and includes abypass passage 7. Thebypass passage 7 includes asub-bypass passage 9 that branches off from thebypass passage 7. - The
bypass passage 7 is a passage introducing a part of the intake air flowing through theintake air channel 2 and extends in a direction parallel to the first flowing direction f1. Thebypass passage 7 includes abypass inlet 7 a located uppermost stream of thebypass passage 7 and abypass outlet 7 b located downmost stream of thebypass passage 7. Thebypass passage 7 further includes anoutlet throttle 7 c located at a position adjacent to thebypass outlet 7 b and throttling the flow of the intake air passing thebypass passage 7. - The
sub-bypass passage 9 is a passage introducing a part of the intake air flowing through thebypass passage 7. Thesub-bypass passage 9 includes asub-bypass inlet 9 a through which the part of the intake air flowing through thebypass passage 7 flows into and asub-bypass outlet 9 b through which the intake air flowing through thesub-bypass passage 9 is returned to theintake air channel 2. Thesub-bypass passage 9 rotates the intake air flowing into thesub-bypass inlet 9 a in thehousing 3 and introduces the intake air to thesub-bypass outlet 9 b. According to the present embodiment, thesub-bypass passage 9 extends from thesub-bypass inlet 9 a in a direction different from the first flowing direction f1. Thus, a foreign matter such as a dust or an oil which is included in theintake air channel 2 and enters thebypass inlet 7 a is separated to thebypass outlet 7 b, and it can be suppressed that the foreign matter enters thesub-bypass passage 9. - The
flow sensing chip 5 includes asensing surface portion 10 located at a surface of theflow sensing chip 5. Thesensing surface portion 10 senses the flow volume of the intake air. Thesensing surface portion 10 is a planar shape. Thesensing surface portion 10 is a heat transmission type and measures the flow volume by a heat transmission between thesensing surface portion 10 and the intake air passing thesub-bypass passage 9. Thesensing surface portion 10 includes a heat generation resistor and a temperature sensing resistor that are located at a surface of thesensing surface portion 10. - The
sensing surface portion 10 generates an electrical signal is response to the flow volume of the intake air of thesub-bypass passage 9. Theflow sensing chip 5 outputs the electrical signal to an ECU that is not shown via a connection terminal in aconnector 11. In other words, theflow sensing chip 5 indirectly outputs an electrical signal in response to the flow volume of the intake air in theintake air channel 2. According to the present embodiment, a direction where the intake air in a center part of thesub-bypass passage 9 flows is referred to as a second flowing direction f2. The center part of thesub-bypass passage 9 is a part of thesub-bypass passage 9 that is located at a center region of thesub-bypass passage 9. A wall surface of a flowing passage wall constituting thesub-bypass passage 9 in the center part hardly affects the flow of the intake air. - The
flow sensing chip 5 is supported by asupport portion 13, and thesensing surface portion 10 is exposed to thesub-bypass passage 9. Specifically, theflow sensing chip 5 is supported by thesupport portion 13 such that the surface of thesensing surface portion 10 is located in a direction parallel to the second flowing direction f2. Thesensing surface portion 10 is located on a part of the surface of theflow sensing chip 5. According to the first embodiment, the first flowing direction f1 is opposite to the second flowing direction f2. - The
sub-bypass passage 9 is throttled by athrottle portion 15 such that a cross-sectional area of thesub-bypass passage 9 perpendicular to the second flowing direction f2 decreases in accordance with a decrease in distance from a gravity center of thesensing surface portion 10 to a center of the cross-sectional area in the direction parallel to the second flowing direction f2. Thethrottle portion 15 is a part of a first flowingpassage wall 16 a constituting thesub-bypass passage 9 and faces thesensing surface portion 10. A second flowingpassage wall 16 b constituting thesub-bypass passage 9 is opposite to the first flowingpassage wall 16 a. In other words, theflow sensing chip 5 is supported between a pair of flowing passage walls that is the first flowingpassage wall 16 a and the second flowingpassage wall 16 b by thesupport portion 13. According to the present embodiment, thehousing 3 includes the first flowingpassage wall 16 a and the second flowingpassage wall 16 b. - The
throttle portion 15 throttles the cross-sectional area of thesub-bypass passage 9 such that a distance from thesensing surface portion 10 to the first flowingpassage wall 16 a at the cross-sectional area in a direction perpendicular to thesensing surface portion 10 decreases in accordance with a decrease in distance from the gravity center of thesensing surface portion 10 to the center of the cross-sectional area in the direction parallel to the second flowing direction f2. Thethrottle portion 15 extends in the direction parallel to the second flowing direction f2. Thethrottle portion 15 includes afirst throttle portion 15 u located upstream of the gravity center of thesensing surface portion 10 in the second flowing direction f2 and asecond throttle portion 15 d located downstream of the gravity center of thesensing surface portion 10 in the second flowing direction f2. Thethrottle portion 15 is a shape elongated in the direction parallel to the second flowing direction f2. - A position where the
first throttle portion 15 u starts is referred to as a first start point position αu, and a position of thefirst throttle portion 15 u where a distance between the gravity center of thesensing surface portion 10 and thefirst throttle portion 15 u is shortest is referred to as a first end point position βu. In this case, the distance is referred to as a shortest distance between the gravity center of thesensing surface portion 10 and thefirst throttle portion 15 u. The first start point position αu and the first end point position βu define a first imagination line γu. The first imagination line γu and the second flowing direction f2 define a first angle δu that is in a range from 0 degrees to 20 degrees. - The first start point position αu is located uppermost stream of the
first throttle portion 15 u in the second flowing direction f2. According to the present embodiment, at the position where the distance between thefirst throttle portion 15 u and the gravity center of thesensing surface portion 10 is shortest, a total distance that is a sum of a distance between the gravity center of thesensing surface portion 10 and the first flowingpassage wall 16 a at thefirst throttle portion 15 u in the direction perpendicular to thesensing surface portion 10 and a distance between the gravity center of thesensing surface portion 10 and the first flowingpassage wall 16 a at thefirst throttle portion 15 u in the direction parallel to the second flowing direction f2 becomes shortest. In this case, the total distance is equivalent to the shortest distance between the gravity center of thesensing surface portion 10 and thefirst throttle portion 15 u. - When plural start point positions au exist, the first start point position αu is a position where a distance between the first start point position αu and the first end point position βu is shortest. In this case, the distance is referred to as a shortest distance between the first start point position αu and the first end point position βu. According to the present embodiment, at the position where the distance between the first start point position αu and the first end point position βu is shortest, a total distance that is a sum of a distance between the first start point position αm and the first end point position βu in the direction perpendicular to the
sensing surface portion 10 and a distance between the first start point position αm and the first end point position βu in the direction parallel to the second flowing direction f2 becomes shortest. In this case, the total distance is equivalent to the shortest distance between the first start point position αu and the first end point position βu. - A position where the
second throttle portion 15 d starts is referred to as a second start point position αd, and a position of thesecond throttle portion 15 d where a distance between the gravity center of thesensing surface portion 10 and thesecond throttle portion 15 d is shortest is referred to as a second end point position βd. In this case, the distance is referred to as a shortest distance between the gravity center of thesensing surface portion 10 and thesecond throttle portion 15 d. The second start point position αd and the second end point position βd define a second imagination line γd. The second imagination line γd and the second flowing direction f2 define a second angle δd that is in a range from 0 degrees to 20 degrees. According to the present embodiment, the second flowing direction f2 is parallel to thesensing surface portion 10. The second start point position αd is located lowermost stream of thesecond throttle portion 15 d in the second flowing direction f2. - The
first throttle portion 15 u and thesecond throttle portion 15 d have surfaces that are curved surfaces protruding inwardly in a radial direction of thesub-bypass passage 9. Specifically, thethrottle portion 15 including thefirst throttle portion 15 u and thesecond throttle portion 15 d includes a side surface facing thesensing surface portion 10. In this case, the side surface is also a side surface of a cylinder having an axis extending in a height direction that is perpendicular to the second flowing direction f2 and is parallel to thesensing surface portion 10. - According to the present embodiment, in the
flow measuring device 1, thesub-bypass passage 9 is throttled by thefirst throttle portion 15 u such that the cross-sectional area of thesub-bypass passage 9 perpendicular to the second flowing direction f2 decreases in accordance with a decrease in distance from the gravity center of thesensing surface portion 10 to the center of the cross-sectional area in the direction parallel to the second flowing direction f2. Thefirst throttle portion 15 u is a part of the first flowingpassage wall 16 a and faces thesensing surface portion 10. Thefirst throttle portion 15 u throttles the cross-sectional area of thesub-bypass passage 9 such that the distance from thesensing surface portion 10 to the first flowingpassage wall 16 a at the cross-sectional area in the direction perpendicular to thesensing surface portion 10 decreases in accordance with a decrease in distance from the gravity center of thesensing surface portion 10 to the center of the cross-sectional area in the direction parallel to the second flowing direction f2. - Since the first start point position αm is a position where the
first throttle portion 15 u starts and the first end point position βu is the position of thefirst throttle portion 15 u where the distance between the gravity center of thesensing surface portion 10 and thefirst throttle portion 15 u is shortest, the first angle δu defined by the first imagination line γu and the second flowing direction f2 is in a range from 0 degrees to 20 degrees. - Thus, since the first flowing
passage wall 16 a gradually varies in thefirst throttle portion 15 u, it can be suppressed that a vortex or a separation is generated in the flow of the intake air in the vicinity of thefirst throttle portion 15 u. Further, a disturb of the flow of the intake air generated by thefirst throttle portion 15 u at thesensing surface portion 10 can be suppressed. Furthermore, in theflow measuring device 1 including thefirst throttle portion 15 u, a sensing accuracy of the flow volume at thesensing surface portion 10 can be improved. - The surface of the
first throttle portion 15 u is a curved surface protruding inwardly in the radial direction of thesub-bypass passage 9. Thus, a variation relative to a flowing direction of the surface of thefirst throttle portion 15 u can be maintained to be smooth, and the cross-sectional area of thesub-bypass passage 9 perpendicular to the second flowing direction f2 can be decreased. Further, it can be suppressed that the vortex or the separation is generated in the flow of the intake air in the vicinity of thefirst throttle portion 15 u, and it can be reduced that a pressure loss is generated in thesub-bypass passage 9. - The
first throttle portion 15 u and thesecond throttle portion 15 d are located upstream and downstream of thesensing surface portion 10 in the second flowing direction f2, respectively. Since thesecond throttle portion 15 d is located downstream of thesensing surface portion 10 in the second flowing direction f2, theflow measuring device 1 can properly measure the flow volume in a case where a pulse flow is generated in response to an operation of a piston of the internal combustion engine. In other words, when a flow of a gas flowing from downstream to upstream, a flow rate at thesensing surface portion 10 can be ensured, and theflow measuring device 1 can properly measure the flow volume. -
FIGS. 4 and 5 are graphs plotting measuring errors of when the first angle δu is changed. As shown inFIG. 4 , when a vibration frequency of the flow volume is low, the measuring error is relatively small without respect to a value of the first angle δu, and theflow measuring device 1 has a characteristic that changes in response to a change of the flow volume. In the change of the flow volume, the flow volume increases or decreases. As shown inFIG. 5 , when the vibration frequency of the flow volume is high, the measuring error increases in a case where the first angle δu exceeds 20 degrees, and the characteristic is deteriorated. Since the vibration frequency increases, the vortex or the separation is readily generated in the flow of the intake air, and a level of an influence of the first angle δu on the measuring error becomes higher. According to the present embodiment, the vibration frequency of the flow volume is equivalent to a vibration frequency of the pulse flow generated in response to the operation of the piston of the internal combustion engine. The vibration frequency of the flow volume has a predetermined value as a central value, and indicates a frequency of when the flow volume changes at a predetermined vibration amplitude. - Referring to
FIG. 6 , components of theflow measuring device 1 according to a second embodiment of the present disclosure that are different from that according to the first embodiment will be described. In addition, the substantially same parts and the components as the embodiments of the present disclosure are indicated with the same reference numeral. According to the present embodiment, in theflow measuring device 1, thefirst throttle portion 15 u includes asurface 17 u that is a planar surface. Further, according to the present embodiment, thesecond throttle portion 15 d is cancelled. Thus, according to the present embodiment, thefirst throttle portion 15 u is referred to as athrottle portion 15 u. -
FIG. 6 indicates a start point position αu, an end point position βu, an imagination line γu and an angle δu that are equivalent to the first start point position αu, the first end point position βu, the first imagination line γu and the first angle δu of the first embodiment. Specifically, the start point position αu is located upstream of thesensing surface portion 10 that is asensing portion 18 in a flowing direction f2 that is equivalent to the second flowing direction f2 of the first embodiment. Thesurface 17 u of thethrottle portion 15 u and the flowing direction f2 define an angle that is equal to the angle δu. - Thus, a variation relative to a flowing direction of the surface of the
throttle portion 15 u can be maintained to be smooth, the cross-sectional area of thesub-bypass passage 9 perpendicular to the flowing direction f2 can be decreased at thesensing portion 18, and the flow rate at thesensing portion 18 can be ensured. Since the cross-sectional area gradually varies, a variation amount of the flow rate generated by thethrottle portion 15 u in the vicinity of thesurface 17 u is small, it can be suppressed that a vortex is generated. Since thesurface 17 u is a planar surface, it is difficult that a flow rate variation in a direction perpendicular to a flow flowing in a direction along thesurface 17 u is generated, and it can be suppressed that the separation is generated. In addition, since thesurface 17 u is a planar surface, thesurface 17 u is readily to be formed. - Referring to
FIG. 7 , components of theflow measuring device 1 according to a third embodiment of the present disclosure that are different from that according to the second embodiment will be described. According to the present embodiment, in theflow measuring device 1, asecond throttle portion 20 that is different from thefirst throttle portion 15 u is located on the second flowingpassage wall 16 b. Since at least two throttle portions are provided in thesub-bypass passage 9, the cross-sectional area of thesub-bypass passage 9 can be further decreased when the angle δu is maintained to be smaller than 20 degrees. Then, the flow rate of the intake air at thesensing surface portion 10 can be further increased, and a heat transmission performance and the sensing accuracy can be further stabilized. - When the
first throttle portion 15 u is provided at the first flowingpassage wall 16 a and the vortex directly reaches thesensing surface portion 10, the influence of the vortex on the flow of the intake air at thesensing surface portion 10 becomes maximum. Then, it is unlikely that the vortex generated due to the throttle portion located at a flowing passage wall other than the first flowingpassage wall 16 a reaches thesensing surface portion 10, and the influence of the vortex on the flow of the intake air at thesensing surface portion 10 decreases. Thus, thesecond throttle portion 20 located on the second flowingpassage wall 16 b does not affect the flow of the intake air at thesensing surface portion 10, and thesecond throttle portion 20 can adjust the cross-sectional area of thesub-bypass passage 9. - According to the first embodiment, when the vibration frequency of the flow volume is high and the first angle δu exceeds 20 degrees, the measuring error increases. According to a fourth embodiment of the present disclosure, when the vibration frequency of the flow volume is high and the first angle δu is 30 degrees, the measuring error is still relatively small. According to the present embodiment, components of the
flow measuring device 1 that are different from that according to the first embodiment will be described. - According to the present embodiment, as shown in
FIG. 8 , a part of thebypass passage 7 from thebypass inlet 7 a to thebypass outlet 7 b is referred to as a passingpassage 8. The passingpassage 8 includes an upstream end portion where thebypass inlet 7 a is located and a downstream end portion where thebypass outlet 7 b is located. The passingpassage 8 extends in the direction parallel to the first flowing direction f1 of theintake air channel 2. According to the present embodiment, thesub-bypass passage 9 can be referred to as a branch passage that branches off from an intermediate part of the passingpassage 8. - According to the present embodiment, as shown in
FIG. 9 , thefirst throttle portion 15 u includes an inner peripheral surface straightly extending from the first start point position αu to the first end point position αd, and thesecond throttle portion 15 d includes an inner peripheral surface straightly extending from the second start point position βu to the second end point position βd. According to the present embodiment, the inner peripheral surface of thefirst throttle portion 15 u is equivalent to a surface of thefirst throttle portion 15 u according to the first embodiment. According to the present disclosure, thefirst throttle portion 15 u and thesecond throttle portion 15 d include inner peripheral surfaces that may be have a part that is recessed or protruded or curved, respectively. The first angle δu and the second angle δd are equal to 30 degrees. Thefirst throttle portion 15 u is equivalent to an upstream throttle portion. Thesensing surface portion 10 is referred to as a sensing portion. - A pair of flowing passage walls including the first flowing
passage wall 16 a and the second flowingpassage wall 16 b is arranged in an arrangement direction that is referred to as a width direction X. The first flowingpassage wall 16 a includes thefirst throttle portion 15 u and thesecond throttle portion 15 d, and the second flowingpassage wall 16 b excludes thefirst throttle portion 15 u and thesecond throttle portion 15 d. The width direction X is an orthogonal direction that is perpendicular to the second flowing direction f2. Thesupport portion 13 is made of a synthetic resin material and is a plate shape. Thesupport portion 13 divides thesub-bypass passage 9 into two regions in the width direction. Thesupport portion 13 is located to be parallel to the first flowingpassage wall 16 a and the second flowingpassage wall 16 b and extends in the direction parallel to the second flowing direction f2. Thesupport portion 13 is also located to be parallel to a direction in which the first start point position αm and the second start point position αd are arranged. Thesupport portion 13 includes a firstopposite surface 13 a facing the first flowingpassage wall 16 a and a secondopposite surface 13 b facing the second flowingpassage wall 16 b. Theflow sensing chip 5 and thesensing surface portion 10 are located on the firstopposite surface 13 a. - The
support portion 13 has a support length L1 that is a length of thesupport portion 13 in the direction parallel to the second flowing direction f2 that is equal to a throttle length La that is a total length of thefirst throttle portion 15 u and thesecond throttle portion 15 d in the direction parallel to the second flowing direction f2. Theflow sensing chip 5 and thesensing surface portion 10 are located at a center of thesupport portion 13 in the direction parallel to the second flowing direction f2. In other words, theflow sensing chip 5 and thesensing surface portion 10 are located such that center lines of theflow sensing chip 5 and thesensing surface portion 10 that are parallel to the width direction X match a center line C of thesupport portion 13 that is perpendicular to the second flowing direction f2. A first support distance L2 that is a distance from an upstream end of thesupport portion 13 to the center line C is equal to a second support distance L3 that is a distance from the center line C to a downstream end of thesupport portion 13. - The center line C of the
support portion 13 is located at a position upstream of the first end point position βu and the second end point position βd in the second flowing direction f2. The upstream end of thesupport portion 13 is located upstream of the first start point position αu in the second flowing direction f2, and the downstream end of thesupport portion 13 is located upstream of the second start point position αd in the second flowing direction f2. The center line C, the first end point position βu and the second end point position βd define a distance in the direction parallel to the second flowing direction f2 that is referred to as a center shift distance L4. The upstream end of thesupport portion 13 and the first start point position αu define a distance that is referred to as an upstream shift distance L5. The downstream end of thesupport portion 13 and the second start point position αd define a distance that is referred to as a downstream shift distance L6. Since the support length L1 of thesupport portion 13 is equal to the throttle length La of thefirst throttle portion 15 u and thesecond throttle portion 15 d, the center shift distance L4, the upstream shift distance L5 and the downstream shift distance L6 are equal to each other. - The throttle length La is also a distance from the first start point position αu to the second start point position αd. The
first throttle portion 15 u located upstream of the gravity center of thesensing surface portion 10 has a length in the direction parallel to the second flowing direction f2 that is referred to as a first throttle length Lb and is equal to a length of thesecond throttle portion 15 d located downstream of the gravity center of thesensing surface portion 10 in the direction parallel to the second flowing direction f2 that is referred to as a second throttle length Lc. The throttle length La is a sum of the first throttle length Lb and the second throttle length Lc. In this case, the first angle δu is equal to the second angle δd, and the first end point position βu and the second end point position βd are located at a center between the first start point position αu and the second start point position αd. - The
sensing surface portion 10 is located between the first start point position αu and the first end point position βu or between the first start point position αu and the second end point position βd in the direction parallel to the second flowing direction f2. Thesensing surface portion 10 is located at a position close to the first end point position βu and the second end point position βd, and thesensing surface portion 10 does not protrude to a position downstream of the first end point position βd and the second end point position βd in the second flowing direction f2. Thesensing surface portion 10 is located to be close to the first end point position βu and the second end point position βd such that theflow sensing chip 5 protrudes to a position downstream of the first end point position βu and the second end point position βd in the second flowing direction f2. In a configuration that thesensing surface portion 10 does not protrude to a position downstream of the first end point position βu and the second end point position βd in the second flowing direction f2, a half of a sensing length L7 that is a length of thesensing surface portion 10 in the direction parallel to the second flowing direction f2 is shorter than the center shift distance L4. In this case, a center part of thesensing surface portion 10 is located upstream of the first end point position βu and the second end point position Pd. - The
support portion 13 is located at a position where the first flowingpassage wall 16 a is closer to thesupport portion 13 than the second flowingpassage wall 16 b is in the width direction X. A first facing distance B1 that is a distance from the first start point position αu and the second start point position αd to thesupport portion 13 in the width direction X is shorter than a second facing distance B2 that is a distance from thesupport portion 13 to the second flowingpassage wall 16 b in the width direction X. A gap distance B3 that is a distance from the first end point position βu and the second end point position βd to thesupport portion 13 in the width direction X is shorter than a throttle distance B4 that is a distance from the first start point position αm and the second start point position αd to the first end point position βu and the second end point position βd in the width direction X. The first facing distance B1 is a sum of the gap distance B3 and the throttle distance B4. The gap distance B3 is longer than a thickness of thesupport portion 13 and a thickness of theflow sensing chip 5. - A space between the first flowing
passage wall 16 a and thesupport portion 13 is referred to as afirst region 21 a where thesensing surface portion 10 is located, and a space between thesupport portion 13 and the second flowingpassage wall 16 b is referred to as asecond region 21 b. According to the present embodiment, thefirst region 21 a is equivalent to a sensing region, and thesecond region 21 b is equivalent to an opposite region. Thesupport portion 13 is located between thesensing surface portion 10 and thesecond region 21 b. A width of thefirst region 21 a in the width direction X gradually decreases from the first start point position αu to the first end point position βu in the second flowing direction f2 and gradually increases from the second end point position βd to the second start point position αd in the second flowing direction f2. - The first flowing
passage wall 16 a further includes anupstream wall surface 22 a that is a wall surface located upstream of the first start point position αu and adownstream wall surface 22 b that is a wall surface located downstream of the second start point position ad. Thus, thefirst region 21 a is also defined by theupstream wall surface 22 a and thesupport portion 13. Theupstream wall surface 22 a and thedownstream wall surface 22 b are in contact with the first start point position αu and the second start point position αd, respectively. A distance from theupstream wall surface 22 a and thedownstream wall surface 22 b to thesupport portion 13 in the width direction X is equal to the first facing distance B1. - According to the present embodiment, since the inner peripheral surfaces of the
first throttle portion 15 u and thesecond throttle portion 15 d extends straightly, the first angle δu is equal to a slope angle of the inner peripheral surface of thefirst throttle portion 15 u relative to theupstream wall surface 22 a and the second angle δd is equal to a slope angle of the inner peripheral surface of thesecond throttle portion 15 d relative to thedownstream wall surface 22 b. - The intake air flowing into a position upstream of the
support portion 13 in thesub-bypass passage 9 is divided into two parts that are a first intake air flowing into thefirst region 21 a and a second intake air flowing into thesecond region 21 b. Since the width of thesecond region 21 b is greater than the width of thefirst region 21 a, the foreign matter included in the intake air flows into thesecond region 21 b more readily than thefirst region 21 a. In other words, a configuration that the foreign matter is difficult to flow into thefirst region 21 a is achieved. Thus, it can be suppressed that the sensing accuracy of thesensing surface portion 10 is deteriorated or thesensing surface portion 10 is damaged due to the foreign matter approaching or being in contact with thesensing surface portion 10. - Since the
support portion 13 extends to a position upstream of thefirst throttle portion 15 u, a width of an upstream end part of thefirst region 21 a is equal to the first facing distance B1. The width of the upstream end part of thefirst region 21 a is greater than that in a configuration where thefirst throttle portion 15 u extends to a position upstream of thesupport portion 13. Thus, comparing the configuration where thefirst throttle portion 15 u extends to a position upstream of thesupport portion 13, a flowing passage area ratio of thefirst region 21 a to thesecond region 21 b becomes greater, and more intake air can flow into thefirst region 21 a. A throttle rate is a ratio of the upstream end part of thefirst region 21 a to a downstream end part of thefirst region 21 a. When the width of the upstream end part becomes greater, it is likely that the throttle rate becomes greater and the flow rate of the first intake air reached the downstream end part of thefirst region 21 a becomes greater. - The flow rate of the first intake air flowing into the
first region 21 a is gradually increased while the first intake air is throttled between thesupport portion 13 and thefirst throttle portion 15 u after the first intake air is straightened between thesupport portion 13 and theupstream wall surface 22 a. A part of thefirst region 21 a between thesupport portion 13 and theupstream wall surface 22 a functions as a straightening region that straightens the first intake air, it is difficult that the disturb that is the vortex or the separation is generated in the first intake air in thefirst region 21 a between thesupport portion 13 and thefirst throttle portion 15 u. Thesensing surface portion 10 senses the flow volume based on a temperature change generated according to the flow volume of the first intake air. Thus, when the temperature change is generated due to the disturb of the flow applied to thesensing surface portion 10, the sensing accuracy of the flow volume by using thesensing surface portion 10 is deteriorated. - Since the
first region 21 a downstream of the first end point position βu and the second end point position βd is enlarged in the second flowing direction f2, the disturb that is the vortex or the separation is readily generated in the first intake air passing through the first end point position βu and the second end point position βd in thefirst region 21 a. When the first intake air flowing along thefirst throttle portion 15 u passes the first end point position βu and the second end point position βd, the disturb is generated at a position immediately downstream of the first end point position βu and the second end point position βd due to a part of the first intake air flowing along thesecond throttle portion 15 d and a part of the first intake air flowing toward thesupport portion 13. - Since the
sensing surface portion 10 is located upstream of the first end point position βu and the second end point position βd, it is difficult that the disturb generated at a position downstream of the first end point position βu and the second end point position βd affects the first intake air between thesensing surface portion 10 and thefirst throttle portion 15 u. Thus, it is difficult that the sensing accuracy of thesensing surface portion 10 is deteriorated due to the disturb generated in the first intake air downstream of the first end point position βu and the second end point position βd. - Recently, since a cylinder of the internal combustion engine is miniaturized in response to a reduction of a component number or a weight reduction, an interference of the intake air in the
intake air channel 2 is readily reduced, and a vibration of a flowing air relative to a flowing direction is readily increased. When a vibration frequency that is a frequency of the vibration is increased, the disturb generated in the intake air in thefirst region 21 a is increased. Then, the measuring error of theflow measuring device 1 is readily increased. According to the present embodiment, the unit of the measuring error is %. In a configuration where thesensing surface portion 10 is located in thesub-bypass passage 9 in thebypass passage 7 without being located in the passingpassage 8 in thebypass passage 7, the measuring error is readily increased in a case where the disturb generated when the intake air flows from the passingpassage 8 into thesub-bypass passage 9 reaches thefirst region 21 a. - As shown in
FIG. 10 , similar to the first embodiment, when the vibration frequency is a first frequency that is relatively low, the measuring error is in an allowable range in a case where the first angle δu is larger than 20 degrees. In this case, a measuring result of theflow measuring device 1 indicates a characteristic that changes in response to a change of the intake air in theintake air channel 2. As shown inFIG. 10 , when the first angle δu is up to 30 degrees or 40 degrees, the measuring error is still in the allowable range. According to the present embodiment, the first frequency may be 100 Hz, and the allowable range of the measuring error may be less than or equal to 3%. - According to the first embodiment, when the vibration frequency is a second frequency that is relative high, it is assumed that the measuring error is sharply increased to be out of the allowable range in a case where the first angle δu exceeds 20 degrees. According to the present embodiment, as shown in
FIG. 11 , the measuring error is still in the allowable range in a case where the first angle δu exceeds 20 degrees and is up to a value slightly exceeding 30 degrees, and the measuring error is sharply increased to be out of the allowable range in a case where the first angle δu exceeds the value slightly exceeding 30 degrees. In this case, it is difficult that the disturb is generated in the first intake air in thefirst region 21 a in a case where thesupport portion 13 faces theupstream wall surface 22 a in thefirst region 21 a and thesensing surface portion 10 is located upstream of the first end point position βu and the second end point position βd. - According to the present embodiment, since the first angle δu and the second angle δd are set to 30 degrees by the
first throttle portion 15 u and thesecond throttle portion 15 d, the measuring error of theflow measuring device 1 can be reduced more than that in a case where the first angle δu and the second angle δd are set to be larger than 30 degrees. - According to the present embodiment, since the
sensing surface portion 10 is located between the first start point position αu and the first end point position βu, it is difficult that the disturb generated in the flow downstream of the first end point position βu is applied to thesensing surface portion 10. Thus, it can be suppressed that the sensing accuracy of thesensing surface portion 10 is deteriorated due to the disturb generated in the flow downstream of the first end point position βu. Further, since thesensing surface portion 10 is located at a position be close to the first end point position βu and the second end point position βd where the flow rate of the first intake air is readily increased in thefirst region 21 a, the flow rate of the first intake air applied to thesensing surface portion 10 is readily increased. Thus, the sensing accuracy of thesensing surface portion 10 can be improved. - According to the present embodiment, the
support portion 13 extends to a position upstream of the first start point position αu. Thus, the first intake air flowing into thefirst region 21 a flows between thesupport portion 13 and theupstream wall surface 22 a to be straightened before the first intake air reaches thefirst throttle portion 15 u. Thus, it is difficult that the disturb is generated in the first intake air reaches thesensing surface portion 10. - According to the present embodiment, the gap distance B3 is shorter than the throttle distance B4. In this case, since the flow rate of the first intake air reached the first end point position βu and the second end point position βd in the
first region 21 a is increased more readily than the flow rate of the first intake air passing the first start point position αu, the sensing accuracy of thesensing surface portion 10 can be improved. - According to the present embodiment, the first facing distance B1 is shorter than the second facing distance B2. In this case, since the width of the
first region 21 a is smaller than the width of thesecond region 21 b, a probability that the foreign matter enters thefirst region 21 a can be reduced. Thus, it can be suppressed that the sensing accuracy of thesensing surface portion 10 is deteriorated or thesensing surface portion 10 is damaged due to the foreign matter. - According to the fourth embodiment, the first end point position βu matches the second end point position βd. According to a fifth embodiment of the present disclosure, as shown in
FIG. 12 , the first end point position βu and the second end point position βd are separated from each other in the direction parallel to the second flowing direction f2. According to the present embodiment, components of theflow measuring device 1 that are different from that according to the fourth embodiment will be described. - According to the present embodiment, a
connection portion 23 that is connected with thefirst throttle portion 15 u and thesecond throttle portion 15 d is located between thefirst throttle portion 15 u and thesecond throttle portion 15 d. Theconnection portion 23 includes an inner peripheral surface extending in a direction parallel to theupstream wall surface 22 a and thedownstream wall surface 22 b. Theconnection portion 23 has a connection length Ld that is a length of the connection portion in the direction parallel to the second flowing direction f2. The connection length Ld is also a distance from the first end point position βu to the second end point position βd. - The
sensing surface portion 10 is located to face theconnection portion 23. Specifically, thesensing surface portion 10 is located between the first end point position βu and the second end point position βd in the direction parallel to the second flowing direction f2. The connection length Ld is longer than a chip length L8 that is a length of theflow sensing chip 5 in the direction parallel to the second flowing direction f2. Thesensing surface portion 10 is located at a position close to the first end point position βu such that theflow sensing chip 5 extends to a position upstream of the first end point position βu in the second flowing direction f2. Theconnection portion 23 includes an upstream end located upstream of the first end point position βu and a downstream end located downstream of the second end point position βd. - According to the present embodiment, the gap distance B3 is equal to the throttle distance B4. However, the gap distance B3 may be longer than the throttle distance B4. In this case, since the width of the
first region 21 a in the width direction X gradually decreases in accordance with a decrease in distance between a position of the firstopposite surface 13 a at a cross-sectional area including the width and the gravity center of thesensing surface portion 10 in the direction parallel to the second flowing direction f2, the flow rate of the first intake air flowing between theconnection portion 23 and thesupport portion 13 can be properly increased. - According to the present embodiment, a space of the
first region 21 a between theconnection portion 23 and thesupport portion 13 is referred to as a most-throttled region. Since thesensing surface portion 10 is located in the most-throttled region, the flow rate of the first intake air applied to thesensing surface portion 10 can be sufficiently increased. Further, since thesensing surface portion 10 is located upstream of the second end point position βd as the same as that according to the fourth embodiment, it is difficult that the disturb such as the vortex generated in the flow when the intake air passes through the second end point position βd. Thus, it can be suppressed that the sensing accuracy of thesensing surface portion 10 is deteriorated due to the disturb of the flow generated downstream of the second end point position βd. - The above embodiments can be change to various embodiments within the spirit and scope of the present disclosure. According to the first embodiment, the
first throttle portion 15 u and thesecond throttle portion 15 d have surfaces that are curved surfaces. As shown inFIG. 13 , according to a sixth embodiment of the present disclosure that is a modification of the first embodiment, thefirst throttle portion 15 u and thesecond throttle portion 15 d have surfaces that are planar surfaces. - A space of the
sub-bypass passage 9 between thefirst throttle portion 15 u and thesecond throttle portion 15 d in the direction parallel to the second flowing direction f2 is a constant region where the cross-sectional area of thesub-bypass passage 9 perpendicular to the second flowing direction f2 is minimum and is constant. Thesensing surface portion 10 is located in the constant region. - According to the second embodiment, the cross-sectional area of the
sub-bypass passage 9 perpendicular to the second flowing direction f2 becomes minimum at thesensing surface portion 10. As shown inFIG. 14 , according to a seventh embodiment of the present disclosure that is a modification of the second embodiment, the cross-sectional area of thesub-bypass passage 9 perpendicular to the second flowing direction f2 is minimum at a position downstream of thesensing surface portion 10. - A distance between the first position p1 and the
sensing surface portion 10 is a sum of the first distance d1 and the second distance d2 (d1+d2). A first distance d1 is a distance between the first position p1 and thesensing surface portion 10 in a direction perpendicular to the surface of thesensing surface portion 10 and the second flowing direction f2. A second distance d2 is a distance between the first position p1 and thesensing surface portion 10 in the direction parallel to the second flowing direction f2. A third distance d3 is a distance obtained by subtracting the first distance d1 from a distance between the second position p2 and thesensing surface portion 10 in the direction perpendicular to the surface of thesensing surface portion 10 and the second flowing direction f2. As shown inFIG. 15 , a length of the second line L2 is equal to the distance between the second position p2 and thesensing surface portion 10 in the direction perpendicular to the surface of thesensing surface portion 10 and the second flowing direction f2. Thus, a distance between the second position p2 and thesensing surface portion 10 is equal to a sum of the first distance d1 and the third distance d3 (d1+d3). Since the first angle δu is in a range from 0 degrees to 20 degrees, the second distance d2 is longer than the third distance d3. Then, the distance between the first position p1 and thesensing surface portion 10 is longer than the distance between the second position p2 and thesensing surface portion 10. Thus, the first end point position βu is set to be located at the second position p2 that is also shown inFIG. 14 . As shown inFIG. 15 , a first position p1 is a position of the surface of the first flowingpassage wall 16 a, and the first position p1 and the gravity center of thesensing surface portion 10 define a first line L1 perpendicular to the surface of the first flowingpassage wall 16 a. A second position p2 is a position of the surface of the first flowingpassage wall 16 a, and the second position p2 and the gravity center of thesensing surface portion 10 define a second line L2 perpendicular to the surface of thesensing surface portion 10. - According to an eighth embodiment of the present disclosure that is another modification of the second embodiment, as shown in
FIGS. 13 and 16 , thefirst throttle portion 15 u is located upstream of thesensing surface portion 10 in the second flowing direction f2. - According to a ninth embodiment of the present disclosure that is another modification of the second embodiment, as shown in
FIGS. 17 and 18 , thefirst throttle portion 15 u is located at a position non-coaxial with thesensing surface portion 10 in the direction parallel to the second flowing direction f2. A distance between thesensing surface portion 10 and thefirst throttle portion 15 u is the distance between the gravity center of thesensing surface portion 10 and thefirst throttle portion 15 u. According to the present embodiment, at the position where the distance between thefirst throttle portion 15 u and the gravity center of thesensing surface portion 10 is shortest, a total distance that is a sum of a distance between the gravity center of thesensing surface portion 10 and the first flowingpassage wall 16 a at thefirst throttle portion 15 u in the direction perpendicular to thesensing surface portion 10 and a distance between the gravity center of thesensing surface portion 10 and the first flowingpassage wall 16 a at thefirst throttle portion 15 u in the direction parallel to the second flowing direction f2 becomes shortest. In this case, the total distance is equivalent to the shortest distance between the gravity center of thesensing surface portion 10 and thefirst throttle portion 15 u. - When plural start point positions au exist, the first start point position αu is a position where a distance between the first start point position αu and the first end point position βu is shortest. In this case, the distance is referred to as a shortest distance between the first start point position αu and the first end point position βu. According to the present embodiment, at the position where the distance between the first start point position αu and the first end point position βu is shortest, a total distance that is a sum of a distance between the first start point position cm and the first end point position βu in the direction perpendicular to the
sensing surface portion 10 and a distance between the first start point position cm and the first end point position βu in the direction parallel to the second flowing direction f2 becomes shortest. In this case, the total distance is equivalent to the shortest distance between the first start point position αu and the first end point position βu. - According to the third embodiment, the
second throttle portion 20 is located on the second flowingpassage wall 16 b facing the first flowingpassage wall 16 a. According to a tenth embodiment of the present disclosure that is a modification of the third embodiment, thesecond throttle portion 20 is located on a flowing passage wall other than the second flowingpassage wall 16 b. Since the vortex slightly affects thesensing surface portion 10 when a flowing passage wall is separated from thesensing surface portion 10 by a predetermined distance, thesecond throttle portion 20 can be located on the first flowingpassage wall 16 a. - According to the first embodiment, the second embodiment and the third embodiment, the
housing 3 includes thesub-bypass passage 9 that is a part of thebypass passage 7. According to an eleventh embodiment of the present disclosure that is a modification of the first embodiment, the second embodiment and the third embodiment, thehousing 3 excludes thesub-bypass passage 9. - According to a twelfth embodiment of the present disclosure that is a modification of the fourth embodiment and the fifth embodiment, the first angle δu and the second angle δd are smaller than 30 degrees. When the first angle δu and the second angle δd are in a range from 0 degrees to 30 degrees, a configuration where the measuring error is not sharply increased until the first angle δu exceeds 30 degrees can be achieved, as shown in
FIG. 11 . Further, similarly, a configuration where the measuring error is not sharply increased until the second angle δd exceeds 30 degrees can be achieved. - According to a thirteenth embodiment of the present disclosure that is another modification of the fourth embodiment and the fifth embodiment, the support length L1 is different from the throttle length La. In a configuration where the support length L1 is longer than the throttle length La, the
support portion 13 extends to a position upstream of thefirst throttle portion 15 u and extends to a position downstream of thesecond throttle portion 15 d in the second flowing direction f2. In a configuration where the support length L1 is shorter than the throttle length La, thesupport portion 13 extends to a position upstream of thefirst throttle portion 15 u. - According to a fourteenth embodiment of the present disclosure that is another modification of the fourth embodiment and the fifth embodiment, the
flow sensing chip 5 and thesensing surface portion 10 is located at a position upstream or downstream of a center position of thesupport portion 13 in the second flowing direction f2. Further, thesensing surface portion 10 is located at a position upstream or downstream of a center position of theflow sensing chip 5 in the second flowing direction f2. - According to a fifteenth embodiment of the present disclosure that is another modification of the fourth embodiment, an entire of the
flow sensing chip 5 is located upstream of the first end point position βu and the second end point position βd. In this case, thesensing surface portion 10 can be located at a position close to the first end point position βu and the second end point position βd in the direction parallel to the second flowing direction f2. - According to a sixteenth embodiment of the present disclosure that is another modification of the fifth embodiment, at least a part of the
sensing surface portion 10 is located upstream of the first end point position βu. For example, an entire of thesensing surface portion 10 is located upstream of the first end point position βu. In this case, thesensing surface portion 10 does not face theconnection portion 23, and thesensing surface portion 10 faces thefirst throttle portion 15 u as the same as that according to the fourth embodiment. - According to a seventeenth embodiment of the present disclosure that is another modification of the fourth embodiment and the fifth embodiment, the first angle δu and the second angle δd are smaller than 30 degrees. For example, the first angle δu is smaller than the second angle δd, or the first angle δu is bigger than the second angle δd. In this case, since a configuration where the measuring error is not sharply increased until the first angle δu exceeds 30 degrees can be achieved as shown in
FIG. 11 , the sensing accuracy of thesensing surface portion 10 and a measuring accuracy of theflow measuring device 1 can be properly maintained. Further, similarly, since a configuration where the measuring error is not sharply increased until the second angle δd exceeds 30 degrees can be achieved, the sensing accuracy of thesensing surface portion 10 and the measuring accuracy of theflow measuring device 1 can be properly maintained. - According to an eighteenth embodiment of the present disclosure that is another modification of the fourth embodiment and the fifth embodiment, the
support portion 13 is not located upstream of the first start point position αu. In this case, when thesupport portion 13 is located at a position where the first flowingpassage wall 16 a is closer to thesupport portion 13 than other flowing passage walls are in the width direction X, the measuring error is not sharply increased until the first angle δu or the second angle δd exceeds 30 degrees. In a configuration where thesupport portion 13 is located at a position where the first flowingpassage wall 16 a is closer to thesupport portion 13 than other flowing passage walls are in the width direction X, the first facing distance B1 is shorter than the second facing distance B2. - According to a nineteenth embodiment of the present disclosure that is another modification of the fourth embodiment and the fifth embodiment, the
support portion 13 is not located at a position where the first flowingpassage wall 16 a is closer to thesupport portion 13 than other flowing passage walls are in the width direction X. In this case, when thesupport portion 13 is located upstream of the first start point position αu in the second flowing direction f2, the measuring error is not sharply increased until the first angle δu or the second angle δd exceeds 30 degrees. - According to an aspect of the present disclosure, the flow measuring device includes a housing including a bypass passage that introduces a part of an air flowing through a duct, and a flow sensing chip located in the bypass passage and including a sensing portion that generates an electrical signal in response to a flow volume of the air in the duct. The bypass passage is throttled by a throttle portion such that a cross-sectional area of the bypass passage perpendicular to a flowing direction in which the air flows through the bypass passage decreases in accordance with a decrease in distance from a gravity center of the sensing surface portion to a center of the cross-sectional area in a direction parallel to the flowing direction. The throttle portion is a part of a flowing passage wall facing the sensing surface portion. A position where the throttle portion starts is referred to as a start point position, the start point position is located upstream of the sensing portion in the flowing direction. The throttle portion includes a surface that is a planar surface, the surface of the throttle portion and the flowing direction define an angle that is in a range from 0 degrees to 30 degrees.
- According to another aspect of the present disclosure, the flow measuring device measures a flow volume of an air. The flow measuring device includes a bypass passage through which the air flows, a sensing portion outputting an electrical signal in response to the flow volume of the air in the bypass passage, a pair of flowing passage walls facing each other, the sensing portion located between the flowing passage walls, and a throttle portion throttling the bypass passage by protruding from the flowing passage walls toward the sensing portion, in an arrangement direction in which the pair of the flowing passage walls is arranged. The throttle portion has a protruding dimension gradually increases in accordance with a decrease in distance from the throttle portion to the sensing portion from an upstream end of the throttle portion in the bypass passage in a flowing direction in which the air flows through the bypass passage. A position of an upstream end of the throttle portion is referred to as a start point position, and a position of the throttle portion where a distance between the gravity center of the sensing surface portion and the throttle portion is shortest is referred to as an end point position. The start point position and the end point position define an imagination line, and the imagination line and the flowing direction define an angle that is in a range from 0 degrees to 30 degrees.
- While the present disclosure has been described with reference to the embodiments thereof, it is to be understood that the disclosure is not limited to the embodiments and constructions. The present disclosure is intended to cover various modification and equivalent arrangements. In addition, while the various combinations and configurations, which are preferred, other combinations and configurations, including more, less or only a single element, are also within the spirit and scope of the present disclosure.
Claims (16)
1. A flow measuring device comprising:
a housing including a bypass passage that introduces a part of an air flowing through a duct; and
a flow sensing chip located in the bypass passage and including a sensing surface portion that generates an electrical signal in response to a flow volume of the air in the duct by a heat transmission between the sensing surface portion and the air flowing through the bypass passage, wherein
the bypass passage includes:
a main-bypass passage introducing the air into the housing through an inlet and discharging the air from the housing through an outlet; and
a sub-bypass passage branching off from the main-bypass passage, the sub-bypass passage introducing a part of the air flowing through the main-bypass passage through a sub-bypass inlet and discharging the air from the housing through a sub-bypass outlet,
the flow sensing chip is disposed in the sub-bypass passage so that the sensing surface portion extends along a flowing direction in which the air flows through the sub-bypass passage,
the sub-bypass passage is throttled by a throttle portion such that a cross-sectional area of the sub-bypass passage perpendicular to the flowing direction decreases in accordance with a decrease in distance from a gravity center of the sensing surface portion to a center of the cross-sectional area in a direction parallel to the flowing direction,
the throttle portion is a part of a flowing passage wall facing the sensing surface portion, the throttle portion throttles the cross-sectional area of the bypass passage such that a distance from the sensing surface portion to the flowing passage wall at the cross-sectional area in a direction perpendicular to the sensing surface portion decreases in accordance with a decrease in distance from the gravity center of the sensing surface portion to the center of the cross-sectional area in the direction parallel to the flowing direction,
a position where the throttle portion starts is referred to as a start point position, and a position of the throttle portion where a distance between the gravity center of the sensing surface portion and the throttle portion is shortest is referred to as an end point position, and
the start point position and the end point position define an imagination line, and the imagination line and the flowing direction define an angle that is in a range from 0 degrees to 20 degrees.
2. The flow measuring device according to claim 1 , wherein
the throttle portion includes a surface that is a planar surface or a curved surface.
3. The flow measuring device according to claim 1 , wherein
another throttle portion that is different from the throttle portion is disposed in the sub-bypass passage.
4. The flow measuring device according to claim 1 , wherein
the throttle portion extends in the direction parallel to the flowing direction, the throttle portion includes a first part located upstream of the gravity center of the sensing surface portion in the flowing direction and a second part located downstream of the gravity center of the sensing surface portion in the flowing direction.
5. A flow measuring device comprising:
a housing including a bypass passage that introduces a part of an air flowing through a duct; and
a flow sensing chip located in the bypass passage and including a sensing surface portion that generates an electrical signal in response to a flow volume of the air in the duct, wherein
the bypass passage includes:
a main-bypass passage introducing the air into the housing through an inlet and discharging the air from the housing through an outlet; and
a sub-bypass passage branching off from the main-bypass passage, the sub-bypass passage introducing a part of the air flowing through the main-bypass passage through a sub-bypass inlet and discharging the air from the housing through a sub-bypass outlet,
the sub-bypass passage is throttled by a throttle portion such that a cross-sectional area of the sub-bypass passage perpendicular to a flowing direction in which the air flows through the sub-bypass passage decreases in accordance with a decrease in distance from a gravity center of the sensing surface portion to a center of the cross-sectional area in a direction parallel to the flowing direction,
the flow sensing chip is disposed in the sub-bypass passage and the throttle portion is a part of a flowing passage wall facing the sensing surface portion,
a position where the throttle portion starts is referred to as a start point position, the start point position is located upstream of the sensing surface portion in the flowing direction, and
the throttle portion includes a surface that is a planar surface, the surface of the throttle portion and the flowing direction define an angle that is in a range from 0 degrees to 20 degrees.
6. A flow measuring device comprising:
a housing including a bypass passage that introduces a part of an air flowing through a duct along a main-flow direction; and
a flow sensing chip located in the bypass passage and including a sensing surface portion that generates an electrical signal in response to a flow volume of the air in the duct by a heat transmission between the sensing surface portion and the air flowing through the bypass passage, wherein
the bypass passage includes:
a main-bypass passage introducing the air into the housing through an inlet and discharging the air from the housing through an outlet; and
a sub-bypass passage branching off from the main-bypass passage, the sub-bypass passage introducing a part of the air flowing through the main-bypass passage through a sub-bypass inlet and discharging the air from the housing through a sub-bypass outlet,
the flow sensing chip is disposed in the sub-bypass passage so that the sensing surface portion extends along a flowing direction in which the air flows through the sub-bypass passage,
the sub-bypass passage is throttled by a throttle portion such that a cross-sectional area of the sub-bypass passage perpendicular to the flowing direction decreases in accordance with a decrease in distance from a gravity center of the sensing surface portion to a center of the cross-sectional area in a direction parallel to the flowing direction,
the throttle portion is a part of a flowing passage wall that is included in the housing and faces the sensing surface portion, the throttle portion throttles the cross-sectional area of the sub-bypass passage such that a distance from the sensing surface portion to the flowing passage wall at the cross-sectional area in a direction perpendicular to the sensing surface portion decreases in accordance with a decrease in distance from the gravity center of the sensing surface portion to the center of the cross-sectional area in the direction parallel to the flowing direction,
a position where the throttle portion starts is referred to as a start point position, and a position of the throttle portion where a distance between the gravity center of the sensing surface portion and the throttle portion is shortest is referred to as an end point position,
the start point position and the end point position define an imagination line, and the imagination line and the flowing direction define an angle that is in a range from 0 degrees to 30 degrees,
the sub-bypass outlet of the sub-bypass passage discharges the air that passed through the sensing surface portion into the duct from the sub-bypass passage, and
the sub-bypass outlet opens along the main-flow direction.
7. The flow measuring device according to claim 6 , wherein
the throttle portion is an upstream throttle portion that is located at a position in the sub-bypass passage upstream of the sensing surface portion and extends in the flowing direction to throttle the sub-bypass passage, and
the sensing surface portion includes a center part that is located between the start point position and the end point position in the flowing direction.
8. The flow measuring device according to claim 7 , further comprising:
a support portion being a plate shape, the support portion supporting the sensing surface portion, the support portion extending to a position upstream of the throttle portion.
9. The flow measuring device according to claim 6 , wherein
a distance from the end point position to a support portion supporting the sensing surface portion is shorter than a distance from the start point position to the end point position, in an orthogonal direction perpendicular to the flowing direction.
10. The flow measuring device according to claim 6 , wherein
the flowing passage wall is a first flowing passage wall, the housing includes a second flowing passage wall facing the first flowing passage wall, a support portion supporting the sensing surface portion is located between the first flowing passage wall and the second flowing passage wall,
the sensing surface portion is located on a surface of the support portion facing the first flowing passage wall,
a distance from the start point position of the first flowing passage wall to the support portion is shorter than a distance from the support portion to the second flowing passage wall.
11. The flow measuring device according to claim 1 , wherein
the sub-bypass inlet of the sub-bypass passage opens in a direction angled relative to a direction along which the air flows through the main-bypass passage.
12. The flow measuring device according to claim 1 , wherein
the sub-bypass passage circumferentially extends inside the housing.
13. The flow measuring device according to claim 5 , wherein
the sub-bypass inlet of the sub-bypass passage opens in a direction angled relative to a direction along which the air flows through the main-bypass passage.
14. The flow measuring device according to claim 5 , wherein
the sub-bypass passage circumferentially extends inside the housing.
15. The flow measuring device according to claim 6 , wherein
the sub-bypass inlet of the sub-bypass passage opens in a direction angled relative to a direction along which the air flows through the main-bypass passage.
16. The flow measuring device according to claim 6 , wherein
the sub-bypass passage circumferentially extends inside the housing.
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US16/591,911 US20200033170A1 (en) | 2016-08-03 | 2019-10-03 | Flow measuring device measuring air flow through a bypass passage throttled by a throttle portion |
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JP2017135655A JP2018025549A (en) | 2016-08-03 | 2017-07-11 | Flow rate measurement device |
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US15/665,721 US10480973B2 (en) | 2016-08-03 | 2017-08-01 | Flow measuring device measuring air flow through a bypass passage throttled by a throttle portion |
US16/591,911 US20200033170A1 (en) | 2016-08-03 | 2019-10-03 | Flow measuring device measuring air flow through a bypass passage throttled by a throttle portion |
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US15/665,721 Division US10480973B2 (en) | 2016-08-03 | 2017-08-01 | Flow measuring device measuring air flow through a bypass passage throttled by a throttle portion |
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US11480455B2 (en) | 2018-02-07 | 2022-10-25 | Denso Corporation | Physical quantity measurement device |
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JP2011027073A (en) * | 2009-07-29 | 2011-02-10 | Denso Corp | Abnormality diagnosis device of internal combustion engine |
JP5327262B2 (en) * | 2011-04-04 | 2013-10-30 | 株式会社デンソー | Thermal air flow meter |
JP5758850B2 (en) | 2012-06-15 | 2015-08-05 | 日立オートモティブシステムズ株式会社 | Thermal flow meter |
JP5884769B2 (en) * | 2013-05-09 | 2016-03-15 | 株式会社デンソー | Air flow measurement device |
JP6186244B2 (en) | 2013-10-30 | 2017-08-23 | 日立オートモティブシステムズ株式会社 | Temperature control device for heater for temperature and humidity sensor |
WO2016051940A1 (en) | 2014-09-30 | 2016-04-07 | 日立オートモティブシステムズ株式会社 | Thermal flow meter |
JP6641789B2 (en) * | 2015-08-27 | 2020-02-05 | 株式会社デンソー | Air flow measurement device |
JP2017053787A (en) * | 2015-09-11 | 2017-03-16 | 株式会社デンソー | Air flow measurement device |
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2017
- 2017-08-01 US US15/665,721 patent/US10480973B2/en active Active
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2019
- 2019-10-03 US US16/591,911 patent/US20200033170A1/en not_active Abandoned
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2022
- 2022-08-05 JP JP2022125685A patent/JP2022153665A/en active Pending
Cited By (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US11480455B2 (en) | 2018-02-07 | 2022-10-25 | Denso Corporation | Physical quantity measurement device |
Also Published As
Publication number | Publication date |
---|---|
JP2022153665A (en) | 2022-10-12 |
US20180038723A1 (en) | 2018-02-08 |
DE102017117389A1 (en) | 2018-02-08 |
US10480973B2 (en) | 2019-11-19 |
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