Patent Application
20220155119
The present disclosure relates to an air flow rate measurement device.
Previously, there has been proposed a sensor device that includes a flow rate sensor, which measures a flow rate of air, and a temperature sensor, which measures the temperature of the air.
This section provides a general summary of the disclosure, and is not a comprehensive disclosure of its full scope or all of its features.
According to the present disclosure, there is provided an air flow rate measurement device that includes a housing, a flow rate sensing device and a physical quantity sensing device. The flow rate sensing device is configured to output a signal which corresponds to a flow rate of air flowing in a flow rate measurement passage of the housing. The physical quantity sensing device is configured to output a signal which corresponds to a physical quantity of the air flowing in a physical quantity measurement passage of the housing that is communicated with a physical quantity measurement passage inlet and a physical quantity measurement passage outlet of the housing. The physical quantity measurement passage has a physical quantity measurement passage inner surface that is formed at a part of the physical quantity measurement passage located on a side where a back surface of the housing is placed. The physical quantity measurement passage outlet has an outlet rectifying surface that is connected to a lateral surface of the housing and an end part of the physical quantity measurement passage inner surface located on a side where the lateral surface is placed, and the physical quantity measurement passage outlet is configured to generate a flow of the air in a direction along the lateral surface at a flow of the air in the physical quantity measurement passage outlet when the air in the physical quantity measurement passage outlet flows along the outlet rectifying surface.
The drawings described herein are for illustrative purposes only of selected embodiments and not all possible implementations, and are not intended to limit the scope of the present disclosure.
Previously, there has been proposed a sensor device that includes a flow rate sensor, which measures a flow rate of air, and a temperature sensor, which measures the temperature of the air.
In the sensor device, the air, which is measured with the temperature sensor, is discharged from a hole that is formed at a lateral surface cover. At this time, in some cases, a direction of the flow of the air, which is discharged from the hole of the lateral surface cover, differs from a direction of the flow of the air around the sensor device. Therefore, the air, which flows around the sensor device, is likely to be disturbed when the air, which is discharged from the hole of the lateral surface cover, merges with the air which flows around the sensor device. Therefore, the pressure loss of the air, which flows around the sensor device, may possibly become relatively large.
According to one aspect of the present disclosure, there is provided an air flow rate measurement device including:
a housing that has:
a flow rate sensing device that is configured to output a signal which corresponds to a flow rate of air flowing in the flow rate measurement passage; and
a physical quantity sensing device that is configured to output a signal which corresponds to a physical quantity of the air flowing in the physical quantity measurement passage, wherein:
the physical quantity measurement passage has a physical quantity measurement passage inner surface that is formed at a part of the physical quantity measurement passage located on a side where the back surface is placed; and
the physical quantity measurement passage outlet has an outlet rectifying surface that is connected to the lateral surface and an end part of the physical quantity measurement passage inner surface located on a side where the lateral surface is placed, and the physical quantity measurement passage outlet is configured to generate a flow of the air in a direction along the lateral surface at a flow of the air in the physical quantity measurement passage outlet when the air in the physical quantity measurement passage outlet flows along the outlet rectifying surface.
With the above configuration, the pressure loss of the air, which flows around the air flow rate measurement device, is reduced.
Hereinafter, embodiments of the present disclosure will be described with reference to the drawings. In each of the following embodiments, the same or equivalent portions will be indicated by the same reference signs, and redundant description thereof will be omitted for the sake of simplicity.
An air flow rate measurement device 21 is used, for example, in an air intake system of an engine system 100 installed to a vehicle. First of all, this engine system 100 will be described. Specifically, as shown in
The air intake pipe 11 is shaped into a cylindrical tubular form and has an air intake passage 111. The air intake passage 111 is configured to conduct the air to be drawn into the engine 16.
The air cleaner 12 is installed in the air intake pipe 11 at an upstream side section of the air intake passage 111, which is located on an upstream side in a flow direction of the air flowing in the air intake passage 111. Furthermore, the air cleaner 12 is configured to remove foreign objects, such as dust, contained in the air flowing in the air intake passage 111.
The air flow rate measurement device 21 is located on a downstream side of the air cleaner 12 in the flow direction of the air flowing in the air intake passage 111. The air flow rate measurement device 21 is configured to measure the flow rate of the air, which flows in the air intake passage 111, at a location between the air cleaner 12 and the throttle valve 13. In this embodiment, the air flow rate measurement device 21 is also configured to measure a physical quantity of the air that flows in the air intake passage 111. Details of the air flow rate measurement device 21 will be described later. In this embodiment, the physical quantity of the air, which flows in the air intake passage 111, is a physical quantity that is different from the flow rate of the air, which flows in the air intake passage 111, and this physical quantity is the temperature of the air as discussed later in detail.
The throttle valve 13 is located on a downstream side of the air flow rate measurement device 21 in the flow direction of the air flowing in the air intake passage 111. Furthermore, the throttle valve 13 is shaped into a circular disk form and is rotated by an electric motor (not shown). The throttle valve 13 is configured to adjust a size of a passage cross-sectional area of the air intake passage 111 and thereby adjust the flow rate of the air to be drawn into the engine 16 through rotation of the throttle valve 13. Here, the passage cross-sectional area refers to a cross-sectional area of the flow passage.
The throttle sensor 14 is configured to output a measurement signal, which corresponds to an opening degree of the throttle valve 13, to the electronic control device 18.
The injector 15 is configured to inject the fuel into a combustion chamber 164 of the engine 16 based on a signal outputted from the electronic control device 18 described later.
The engine 16 is an internal combustion engine where a mixture gas, which is a mixture of the air flowing from the air intake passage 111 through the throttle valve 13 and the fuel injected from the injector 15, is combusted in the combustion chamber 164. An explosive force, which is generated by this combustion, causes a piston 162 of the engine 16 to reciprocate in a cylinder 161. Specifically, the engine 16 includes cylinders 161, pistons 162, a cylinder head 163, combustion chambers 164, intake valves 165, an intake valve drive device 166, exhaust valves 167, an exhaust valve drive device 168 and spark plugs 169.
The cylinder 161 is shaped in a tubular form and receives the piston 162. The piston 162 is configured to reciprocate in the cylinder 161 in an axial direction of the cylinder 161. The cylinder head 163 is installed at upper portions of the cylinders 161. Furthermore, the cylinder head 163 is connected to the air intake pipe 11 and the exhaust pipe 17 and has a first cylinder passage 181 and a second cylinder passage 182. The first cylinder passage 181 is communicated with the air intake passage 111. The second cylinder passage 182 is communicated with an exhaust passage 171 of the exhaust pipe 17 described later. The combustion chamber 164 is defined by the cylinder 161, a top surface of the piston 162 and a lower surface of the cylinder head 163. The intake valve 165 is placed in the first cylinder passage 181 and is configured to be driven by the intake valve drive device 166 to open and close the combustion chamber 164 at the first cylinder passage 181 side. The exhaust valve 167 is placed in the second cylinder passage 182 and is configured to be driven by the exhaust valve drive device 168 to open and close the combustion chamber 164 at the second cylinder passage 182 side.
The spark plug 169 is configured to ignite the mixture gas of the combustion chamber 164, which is the mixture of the air flowing from the air intake passage 111 through the throttle valve 13 and the fuel injected from the injector 15, based on the signal outputted from the electronic control device 18.
The exhaust pipe 17 is shaped in a cylindrical tubular form and has the exhaust passage 171. The exhaust passage 171 conducts the gas which is combusted in the combustion chambers 164. The gas, which flows in the exhaust passage 171, is purified by an exhaust gas purification device (not shown).
The electronic control device 18 includes a microcomputer as its main component and thereby has a CPU, a ROM, a RAM, an I/O device and a bus line for connecting these devices. Here, for example, the electronic control device 18 controls the opening degree of the throttle valve 13 based on, for example, the flow rate of the air and the physical quantity of the air measured with the air flow rate measurement device 21 and the current opening degree of the throttle valve 13. Furthermore, the electronic control device 18 controls a fuel injection amount of the respective injectors 15 and ignition timing of the respective spark plugs 169 based on, for example, the flow rate of the air and the physical quantity of the air measured with the air flow rate measurement device 21 and the current opening degree of the throttle valve 13. In
The engine system 100 has the above-described structure. Next, the air flow rate measurement device 21 will be described in detail.
As shown in
As shown in
The holding portion 31 is shaped in a cylindrical tubular form and is fixed to the pipe extension 112 when an outer surface of the holding portion 31 is fitted to an inner surface of the pipe extension 112, Furthermore, a groove, into which the seal member 32 is fitted, is formed at an outer peripheral surface of the holding portion 31.
The seal member 32 is for example, an O-ring and is installed in the groove of the holding portion 31. The seal member 32 closes a passage in the pipe extension 112 when the seal member 32 contacts the pipe extension 112, Thereby, leakage of the air, which flows in the air intake passage 111, to the outside through the pipe extension 112 is limited.
The lid 33 is shaped in a bottomed tubular form and is connected to the holding portion 31 in an axial direction of the holding portion 31. Furthermore, a length of the lid 33, which is measured in a radial direction of the holding portion 31, is larger than a diameter of the pipe extension 112, and the lid 33 closes a hole of the pipe extension 112.
The connector cover 34 is connected to the lid 33 and extends from a radially inner side toward a radially outer side in the radial direction of the holding portion 31. Furthermore, the connector cover 34 is shaped in a tubular form and receives one end parts of the terminals 35.
As shown in
The bypass portion 40 includes a plurality of passages and is shaped in a planar form. Specifically, as shown in
The housing base surface 41 is located on an upstream side in the flow direction of the air flowing in the air intake passage 111. The housing back surface 42 is located on a side that is opposite to the housing base surface 41. The primary housing lateral surface 51 serves as a primary lateral surface and is connected to one end part of the housing base surface 41 and one end part of the housing back surface 42. The secondary housing lateral surface 52 serves as a secondary lateral surface and is connected to another end part of the housing base surface 41 and another end part of the housing back surface 42, which are opposite to the primary housing lateral surface 51. Furthermore, the housing base surface 41, the housing back surface 42, the primary housing lateral surface 51 and the secondary housing lateral surface 52 are respectively shaped in a stepped form.
As shown in
As shown in
As shown in
As shown in
As shown in
As shown in
As shown in
As shown in
The circuit board 76 is, for example, a printed circuit board made of glass, epoxy resin, or the like and is electrically connected to the other end parts of the corresponding terminals 35. Furthermore, as shown in
The physical quantity sensing device 81 is installed to the primary circuit board end part 761 of the circuit board 76 and is opposed to the primary inlet inner surface 61. The physical quantity sensing device 81 outputs a signal that corresponds to the physical quantity of the air which flows in the physical quantity measurement passage inlet 500. In this instance, the physical quantity of the air, which flows in the physical quantity measurement passage inlet 500, is the temperature of the air which flows in the physical quantity measurement passage inlet 500. The physical quantity sensing device 81 includes, for example, a thermistor (not shown) and outputs a signal that corresponds to the temperature of the air which flows in the physical quantity measurement passage inlet 500. Furthermore, since the physical quantity sensing device 81 is installed to the circuit board 76, the output signal of the physical quantity sensing device 81 is transmitted to the electronic control device 18 through the circuit board 76 and the corresponding terminal 35.
Here, the physical quantity measurement passage inlet 500 is configured to generate a flow of the air, which flows from the physical quantity measurement passage inlet 500 toward the primary physical quantity measurement passage outlet 501, at the flow of the air at the primary inlet inner surface 61 side in the physical quantity measurement passage inlet 500. Specifically, the physical quantity measurement passage inlet 500 has a primary inlet rectifying surface 911. As shown in
Furthermore, the physical quantity measurement passage inlet 500 generates a flow of the air, which flows from the physical quantity measurement passage inlet 500 toward the secondary physical quantity measurement passage outlet 502, at the flow of the air at the secondary inlet inner surface 62 side in the physical quantity measurement passage inlet 500. Specifically, the physical quantity measurement passage inlet 500 has a secondary inlet rectifying surface 912, The secondary inlet rectifying surface 912 is connected to an end part of the secondary inlet inner surface 62, which is located on the housing back surface 42 side, and an end part of the secondary outlet inner surface 72, which is located on the physical quantity measurement passage inlet 500 side. Furthermore, the secondary inlet rectifying surface 912 extends from the end part of the secondary inlet inner surface 62, which is located on the housing back surface 42 side, toward the secondary physical quantity measurement passage outlet 502. Here, the secondary inlet rectifying surface 912 extends from the end part of the secondary inlet inner surface 62, which is located on the housing back surface 42 side, in a direction directed toward the secondary housing lateral surface 52 and also toward the housing back surface 42. Furthermore, the secondary inlet rectifying surface 912 is tilted relative to the secondary inlet inner surface 62 and is shaped in a form of a flat surface. The air at the secondary inlet inner surface 62 side in the physical quantity measurement passage inlet 500 flows along the secondary inlet rectifying surface 912. Therefore, the flow of the air, which flows from the physical quantity measurement passage inlet 500 toward the secondary physical quantity measurement passage outlet 502, is generated at the flow of the air at the secondary inlet inner surface 62 side in the physical quantity measurement passage inlet 500.
Furthermore, the primary physical quantity measurement passage outlet 501 has a primary outlet rectifying surface 921 described later. The primary physical quantity measurement passage outlet 501 generates the flow of the air in a direction along the primary housing lateral surface 51 at the flow of the air in the primary physical quantity measurement passage outlet 501 when the air in the primary physical quantity measurement passage outlet 501 flows along the primary outlet rectifying surface 921. Here, it is assumed that the air in the air intake passage 111 flows around the air flow rate measurement device 21, and the air flows in a direction from the housing base surface 41 toward the housing back surface 42. In this case, each of the direction along the primary housing lateral surface 51 and the direction along the secondary housing lateral surface 52 is the direction directed from the housing base surface 41 toward the housing back surface 42.
Specifically, the primary outlet rectifying surface 921 is formed at a part of the primary physical quantity measurement passage outlet 501 located on the housing back surface 42 side. Furthermore, the primary outlet rectifying surface 921 is connected to an end part of the physical quantity measurement passage inner surface 55 located on the primary housing lateral surface 51 side and is also connected to the primary housing lateral surface 51. Furthermore, the primary outlet rectifying surface 921 extends from the end part of the physical quantity measurement passage inner surface 55, which is located on the primary housing lateral surface 51 side, in a direction directed toward both the primary housing lateral surface 51 and the housing back surface 42, Here, the primary outlet rectifying surface 921 is tilted relative to the physical quantity measurement passage inner surface 55 and is shaped in a form of a flat surface. Furthermore, the flow of the air in the direction along the primary housing lateral surface 51 is generated at the flow of the air in the primary physical quantity measurement passage outlet 501 when the air in the primary physical quantity measurement passage outlet 501 flows along the primary outlet rectifying surface 921.
Here, as shown in
Furthermore, in order to clarify the shape of the primary outlet rectifying surface 921, an apex, which is defined by the first bottom edge 971 and the first side edge 941, will be referred to as a first apex P1 as shown in
Furthermore, as shown in FIG, 7, the primary physical quantity measurement passage outlet 501 has a primary outlet upper surface 951 and a primary outlet lower surface 961. The primary outlet upper surface 951 is formed at a part of the primary physical quantity measurement passage outlet 501 located on the upper side, i.e., the terminal 35 side. Furthermore, the primary outlet upper surface 951 is connected to an upper end part of the primary outlet inner surface 71 and an upper end part of the physical quantity measurement passage inner surface 55. The primary outlet lower surface 961 is formed at a part of the primary physical quantity measurement passage outlet 501 located on the lower side, i.e., the side opposite to the terminals 35. The primary outlet lower surface 961 is connected to a lower end part of the primary outlet inner surface 71 and the second side edge 942 of the primary outlet rectifying surface 921. Furthermore, the primary outlet lower surface 961 is tilted relative to the primary outlet upper surface 951 and extends from an end part of the primary outlet lower surface 961, which is connected to the primary outlet inner surface 71, toward the flow rate measurement main passage outlet 432, Furthermore, since the primary outlet lower surface 961 is connected to the primary outlet rectifying surface 921, the primary outlet end 931 serves as an end point of the primary outlet lower surface 961 located on the flow rate measurement main passage outlet 432 side. Therefore, the primary outlet end 931 is the end of the primary outlet rectifying surface 921 located on the flow rate measurement main passage outlet 432 side and is also the end of the primary outlet lower surface 961 located on the flow rate measurement main passage outlet 432 side. Thus, among the air flowing in the primary physical quantity measurement passage outlet 501, the air, which flows through the primary outlet end 931, is more likely to flow toward the flow rate measurement main passage outlet 432.
Furthermore, in the primary physical quantity measurement passage outlet 501, a primary flow passage 981, which is defined by the primary outlet rectifying surface 921 and the primary outlet lower surface 961, is formed. Since the primary outlet rectifying surface 921 is shaped in the form of the triangle, a size of the primary outlet rectifying surface 921 is progressively reduced from the first bottom edge 971 toward the primary outlet end 931. Therefore, as shown in
Furthermore, in
Furthermore, as shown in
Specifically, the secondary outlet rectifying surface 922 is formed at a part of the secondary physical quantity measurement passage outlet 502 located on the housing back surface 42 side. Furthermore, the secondary outlet rectifying surface 922 is connected to an end part of the physical quantity measurement passage inner surface 55 located on the secondary housing lateral surface 52 side and is also connected to the secondary housing lateral surface 52. Furthermore, the secondary outlet rectifying surface 922 extends from the end part of the physical quantity measurement passage inner surface 55, which is located on the secondary housing lateral surface 52 side, in a direction directed toward both the secondary housing lateral surface 52 and the housing back surface 42. Here, the secondary outlet rectifying surface 922 is tilted relative to the physical quantity measurement passage inner surface 55 and is shaped in a form of a flat surface. Furthermore, the flow of the air in the direction along the secondary housing lateral surface 52 is generated at the flow of the air in the secondary physical quantity measurement passage outlet 502 when the air in the secondary physical quantity measurement passage outlet 502 flows along the secondary outlet rectifying surface 922.
Here, as shown in
Furthermore, as shown in
Furthermore, in order to clarify the shape of the secondary outlet rectifying surface 922, an apex, which is defined by the second bottom edge 972 and the third side edge 943, will be referred to as a third apex P3 as shown in
Furthermore, as shown in
Furthermore, like the primary physical quantity measurement passage outlet 501, in the secondary physical quantity measurement passage outlet 502, a secondary flow passage 982, which is defined by the secondary outlet rectifying surface 922 and the secondary outlet lower surface 962, is formed. Since the secondary outlet rectifying surface 922 is shaped in the form of the triangle, a size of the secondary outlet rectifying surface 922 is progressively reduced from the second bottom edge 972 toward the secondary outlet end 932. Therefore, a passage cross-sectional area of the secondary flow passage 982 is progressively reduced in the direction directed from the housing base surface 41 toward the housing back surface 42, i.e., is progressively reduced in the axial direction of the X-axis. As a result, a flow velocity of the air, which is discharged from the secondary physical quantity measurement passage outlet 502, becomes relatively high. In
Furthermore, in
The flow passages of the air, which flows through the physical quantity measurement passage inlet 500, the primary physical quantity measurement passage outlet 501 and the secondary physical quantity measurement passage outlet 502, have the following relationship. Here, in order to indicate the relationship of the flow passages of the air, which flows through the physical quantity measurement passage inlet 500, the primary physical quantity measurement passage outlet 501 and the secondary physical quantity measurement passage outlet 502, the following terms are defined.
As shown in
The physical quantity measurement passage inlet 500, the primary physical quantity measurement passage outlet 501 and the secondary physical quantity measurement passage outlet 502 have the following relationships. As indicated in the following relational expression (1-1), the primary outlet passage cross-sectional area Ao1 is smaller than the inlet passage cross-sectional area Ai and is smaller than the measurement passage cross-sectional area Ai_D. Thus, the flow velocity of the air, which flows in the primary physical quantity measurement passage outlet 501, tends to be higher than the flow velocity of the air, which flows in the physical quantity measurement passage inlet 500, and the flow velocity of the air, which flows in the physical quantity measurement passage 50. Furthermore, as indicated in the following relational expression (1-2), the secondary outlet passage cross-sectional area Ao2 is smaller than the inlet passage cross-sectional area Ai and is smaller than the non-measurement passage cross-sectional area Ai_N. Thus, the flow velocity of the air, which flows in the secondary physical quantity measurement passage outlet 502, tends to be higher than the flow velocity of the air, which flows in the physical quantity measurement passage inlet 500, and the flow velocity of the air, which flows in the physical quantity measurement passage 50.
The air flow rate measurement device 21 is constructed in the above-described manner. Next, the measurement of the flow rate by the air flow rate measurement device 21 will be described. Furthermore, the measurement of the temperature by the air flow rate measurement device 21 will be described with reference to
A portion of the air, which flows in the air intake passage 111, flows into the flow rate measurement main passage inlet 431. The air, which flows from the flow rate measurement main passage inlet 431, flows in the flow rate measurement main passage 43 toward the flow rate measurement main passage outlet 432. A portion of the air, which flows in the flow rate measurement main passage 43, is discharged to the outside of the housing 30 through the flow rate measurement main passage outlet 432.
Furthermore, another portion of the air, which flows in the flow rate measurement main passage 43, flows into the flow rate measurement sub-passage inlet 441. The air, which flows from the flow rate measurement sub-passage inlet 441, flows in the return portion 445 after passing through the introducing portion 443 and the rear vertical portion 444 of the flow rate measurement sub-passage 44. A portion of the air, which flows in the return portion 445, contacts the flow rate sensing device 75. Due to the contact of the flow rate sensing device 75 with the air, the flow rate sensing device 75 outputs a signal that corresponds to the flow rate of the air, which flows in the flow rate measurement sub-passage 44. The output signal of the flow rate sensing device 75 is transmitted to the electronic control device 18 through the corresponding terminal 35. Furthermore, a portion of the air, which flows in the return portion 445, is discharged to the outside of the housing 30 through the front vertical portion 446 and the flow rate measurement sub-passage outlets 442 of the flow rate measurement sub-passage 44,
Furthermore, a portion of the air, which flows in the air intake passage 111, flows into the physical quantity measurement passage inlet 500. As shown in
The physical quantity sensing device 81 outputs a signal that corresponds to the temperature of the air which flows in the physical quantity measurement passage inlet 500. The output signal of the physical quantity sensing device 81 is transmitted to the electronic control device 18 through the circuit board 76 and the corresponding terminal 35. Furthermore, the air, which flows between the primary inlet inner surface 61 and the primary circuit board end part 761, then flows along the primary inlet rectifying surface 911, Thus, the physical quantity measurement passage inlet 500 generates the flow of the air, which flows from the physical quantity measurement passage inlet 500 toward the primary physical quantity measurement passage outlet 501, at the flow of the air at the primary inlet inner surface 61 side in the physical quantity measurement passage inlet 500. The air, which flows along the primary inlet rectifying surface 911, then flows in the primary physical quantity measurement passage outlet 501. The air, which flows in the primary physical quantity measurement passage outlet 501, flows along the primary outlet rectifying surface 921, Therefore, the primary physical quantity measurement passage outlet 501 generates the flow of the air in the direction along the primary housing lateral surface 51 at the flow of the air in the primary physical quantity measurement passage outlet 501. Then, the air, which flows along the primary outlet rectifying surface 921, is discharged from the primary physical quantity measurement passage outlet 501 and merges with the flow of the air flowing in the direction along the primary housing lateral surface 51. In
Also, as indicated in
Furthermore, as indicated in
Also, as indicated in
As discussed above, the airflow rate measurement device 21 measures the flow rate of the air and the temperature of the air. At the air flow rate measurement device 21, a pressure loss of the air, which flows around the air flow rate measurement device 21, is reduced. The reduction of the pressure loss will be described hereinafter.
In the air flow rate measurement device 21, the primary physical quantity measurement passage outlet 501 generates the flow of the air in the direction along the primary housing lateral surface 51, at the flow of the air in the primary physical quantity measurement passage outlet 501. Therefore, an angle, which is defined between the flow direction of the air in the primary physical quantity measurement passage outlet 501 and the direction along the primary housing lateral surface 51, is reduced. Thus, the disturbance of the air, which flows along the primary housing lateral surface 51, by the air, which is discharged from the primary physical quantity measurement passage outlet 501, is limited. As a result, since the disturbance of the air flowing around the air flow rate measurement device 21 is limited, the pressure loss of the air flowing around the air flow rate measurement device 21 is reduced.
Furthermore, the secondary physical quantity measurement passage outlet 502 generates the flow of the air in the direction along the secondary housing lateral surface 52, at the flow of the air in the secondary physical quantity measurement passage outlet 502. Therefore, an angle, which is defined between the flow direction of the air in the secondary physical quantity measurement passage outlet 502 and the direction along the secondary housing lateral surface 52, is reduced. As a result, similar to the above-described one, since the disturbance of the air flowing around the air flow rate measurement device 21 is limited, the pressure loss of the air flowing around the air flow rate measurement device 21 is reduced.
Furthermore, in this instance, the engine 16 is placed on the downstream side of the air flow rate measurement device 21 in the flow direction of the air. Since the pressure loss of the air, which flows around the air flow rate measurement device 21, is reduced at the air flow rate measurement device 21, a reduction in the amount of the air suctioned into the engine 16 is limited. Therefore, the measurement accuracy of the air flow rate measurement device 21 for measuring the flow rate of the air to be suctioned into the engine 16 is improved. As a result, it is possible to improve the controllability and the combustion performance of the engine 16 which are based on the flow rate of the air measured by the air flow rate measurement device 21.
Furthermore, the circuit board 76 is a printed circuit board. Since the printed circuit board is in a form of a relatively thin plate, it is relatively difficult to process the printed circuit board into a shape that conforms the streamline of air. Moreover, since the processing of the printed circuit board is relatively difficult, the dimensional accuracy of the printed circuit board is relatively low. Due to the difficulty of processing on the printed circuit board and the low dimensional accuracy of the printed circuit board, the air around the printed circuit board tends to be unstable. Therefore, in the structure of the previously proposed sensor device, since this unstable flow of the air merges with the flow of the air around the sensor, the air flowing around the sensor tends to be disturbed. However, in the air flow rate measurement device 21, as described above, the air, which is discharged from the primary physical quantity measurement passage outlet 501, and the air, which is discharged from the secondary physical quantity measurement passage outlet 502, are rectified. Therefore, even when the physical quantity sensing device 81 is installed to the circuit board 76, it is possible to limit the disturbance of the air flowing around the air flow rate measurement device 21.
Furthermore, the air flow rate measurement device 21 can provide the following advantages (1) to (6).
(1) The primary physical quantity measurement passage outlet 501 has the primary outlet rectifying surface 921 that is configured to generate the flow of the air in the direction along the primary housing lateral surface 51 at the flow of the air in the primary physical quantity measurement passage outlet 501. Furthermore, the secondary physical quantity measurement passage outlet 502 has the secondary outlet rectifying surface 922 that is configured to generate the flow of the air in the direction along the secondary housing lateral surface 52 at the flow of the air in the secondary physical quantity measurement passage outlet 502. Here, each of the primary outlet rectifying surface 921 and the secondary outlet rectifying surface 922 is shaped in the form of the flat surface. Therefore, the primary outlet rectifying surface 921 and the secondary outlet rectifying surface 922 can be relatively easily formed.
(2) The flow rate measurement main passage inlet 431 is located on the opposite side of the physical quantity measurement passage inlet 500 which is opposite to the terminals 35. Furthermore, when the air flow rate measurement device 21 is installed to the air intake pipe 11, the flow rate measurement main passage inlet 431 is positioned at the center of the air intake passage 111 in the radial direction of the air intake pipe 11. Therefore, the flow rate measurement main passage inlet 431 can introduce the air, which has the relatively high flow velocity among the air flowing in the air intake passage 111, into the flow rate measurement main passage 43. When the air, which has the relatively high flow velocity, flows in the flow rate measurement main passage 43, the air is easily introduced into the flow rate measurement sub-passage 44. Therefore, the measurement accuracy of the air flow rate by the flow rate sensing device 75 is improved.
(3) The primary outlet end 931 is located between the primary physical quantity measurement passage outlet 501 and the flow rate measurement main passage outlet 432 and forms the flow passage of the air which flows from the primary physical quantity measurement passage outlet 501 toward the flow rate measurement main passage outlet 432. Therefore, the air, which is discharged from the primary physical quantity measurement passage outlet 501, merges with the air which is discharged from the flow rate measurement main passage outlet 432, Furthermore, the secondary outlet end 932 is located between the secondary physical quantity measurement passage outlet 502 and the flow rate measurement main passage outlet 432 and forms the flow passage of the air which flows from the secondary physical quantity measurement passage outlet 502 toward the flow rate measurement main passage outlet 432. Therefore, the air, which is discharged from the secondary physical quantity measurement passage outlet 502, merges with the air which is discharged from the flow rate measurement main passage outlet 432. Since the air, which is discharged from the primary physical quantity measurement passage outlet 501, and the air, which is discharged from the secondary physical quantity measurement passage outlet 502, merge with the air, which is discharged from the flow rate measurement main passage outlet 432, the variations in the flow velocity of the air, which flows on the downstream side of the flow rate measurement main passage outlet 432, are reduced. Therefore, the pressure loss of the air, which flows on the downstream side of the flow rate measurement main passage outlet 432, is reduced, and the pressure loss of the air, which flows around the air flow rate measurement device 21, is reduced.
Furthermore, by reducing the pressure loss of the air, which flows on the downstream side of the flow rate measurement main passage outlet 432, the fluctuation of the pressure of the air at the flow rate measurement main passage outlet 432, is reduced. Therefore, the flow of the air, which flows in the flow rate measurement main passage 43, is less likely to change. Since the flow of the air, which flows in the flow rate measurement main passage 43, is less likely to change, the flow of the air, which flows in the flow rate measurement sub-passage 44, is less likely to change. Therefore, the variations in the output signal of the flow rate sensing device 75 are reduced, and thereby the measurement accuracy of the flow rate sensing device 75 for the flow rate of the air, which flows in the flow rate measurement sub-passage 44, is improved.
(4) In the primary physical quantity measurement passage outlet 501, the primary flow passage 981, which is defined by the primary outlet rectifying surface 921 and the primary outlet lower surface 961, is formed. The passage cross-sectional area of the primary flow passage 981 is progressively reduced in the direction directed from the housing base surface 41 toward the housing back surface 42. As a result, the flow velocity of the air, which is discharged from the primary physical quantity measurement passage outlet 501, becomes relatively high. Thus, a difference between the flow velocity of the air, which is discharged from the primary physical quantity measurement passage outlet 501, and the flow velocity of the air, which flows along the primary housing lateral surface 51, can be reduced. Therefore, the disturbance of the air, which flows along the primary housing lateral surface 51, by the air, which is discharged from the primary physical quantity measurement passage outlet 501, is limited. Similarly, in the secondary physical quantity measurement passage outlet 502, the secondary flow passage 982, which is defined by the secondary outlet rectifying surface 922 and the secondary outlet lower surface 962, is formed. The passage cross-sectional area of the secondary flow passage 982 is progressively reduced in the direction directed from the housing base surface 41 toward the housing back surface 42. As a result, the flow velocity of the air, which is discharged from the secondary physical quantity measurement passage outlet 502, becomes relatively high. Thus, similar to the above-described one, the disturbance of the air, which flows along the secondary housing lateral surface 52, by the air, which is discharged from the secondary physical quantity measurement passage outlet 502, is limited.
(5) The primary outlet passage cross-sectional area Ao1 is smaller than the inlet passage cross-sectional area Ai and is smaller than the measurement passage cross-sectional area Ai_D. Therefore, it is possible to increase the flow velocity of the air, which flows in the primary physical quantity measurement passage outlet 501, in comparison to the flow velocity of the air, which flows in the physical quantity measurement passage inlet 500, and the flow velocity of the air, which flows in the physical quantity measurement passage 50. Thereby, the flow velocity of the air, which is discharged from the primary physical quantity measurement passage outlet 501, can be increased. Thus, the difference between the flow velocity of the air, which is discharged from the primary physical quantity measurement passage outlet 501, and the flow velocity of the air, which flows along the primary housing lateral surface 51, can be reduced. Therefore, the disturbance of the air, which flows along the primary housing lateral surface 51, by the air, which is discharged from the primary physical quantity measurement passage outlet 501, is limited. Furthermore, the secondary outlet passage cross-sectional area Ao2 is smaller than the inlet passage cross-sectional area Ai and is smaller than the non-measurement passage cross-sectional area Ai_N. Thus, similar to the above-described one, the disturbance of the air, which flows along the secondary housing lateral surface 52, by the air, which is discharged from the secondary physical quantity measurement passage outlet 502, is limited.
(6) The physical quantity measurement passage inlet 500 generates the flow of the air, which flows from the physical quantity measurement passage inlet 500 toward the primary physical quantity measurement passage outlet 501, at the flow of the air at the primary inlet inner surface 61 side in the physical quantity measurement passage inlet 500. The physical quantity measurement passage inlet 500 facilitates the flow of air from the physical quantity measurement passage inlet 500 to the primary physical quantity measurement passage outlet 501 through the physical quantity measurement passage 50. Therefore, the pressure loss of the air, which flows through the physical quantity measurement passage inlet 500, the physical quantity measurement passage 50 and the primary physical quantity measurement passage outlet 501, is reduced. Thus, the pressure difference between the air, which is discharged from the primary physical quantity measurement passage outlet 501, and the air, which flows along the primary housing lateral surface 51, in the direction along the primary housing lateral surface 51 is reduced. Therefore, the disturbance of the air, which flows along the primary housing lateral surface 51, by the air, which is discharged from the primary physical quantity measurement passage outlet 501, is limited. As a result, since the disturbance of the air flowing around the air flow rate measurement device 21 is limited, the pressure loss of the air flowing around the air flow rate measurement device 21 is reduced. Furthermore, the physical quantity measurement passage inlet 500 generates the flow of the air, which flows from the physical quantity measurement passage inlet 500 toward the secondary physical quantity measurement passage outlet 502, at the flow of the air at the secondary inlet inner surface 62 side in the physical quantity measurement passage inlet 500. Thus, similar to the above-described one, the disturbance of the air, which flows along the secondary housing lateral surface 52, by the air, which is discharged from the secondary physical quantity measurement passage outlet 502, is limited. As a result, since the disturbance of the air flowing around the air flow rate measurement device 21 is limited, the pressure loss of the air flowing around the air flow rate measurement device 21 is reduced.
A second embodiment is the same as the first embodiment except for the configurations of the primary inlet rectifying surface, the secondary inlet rectifying surface, the primary outlet rectifying surface and the secondary outlet rectifying surface.
In the air flow rate measurement device 22 of the second embodiment, the primary inlet rectifying surface 911 is shaped in a form of a curved surface instead of the form of the flat surface. Specifically, as shown in
Furthermore, like the primary inlet rectifying surface 911, the secondary inlet rectifying surface 912 is shaped in a form of a curved surface. Specifically, like the primary inlet rectifying surface 911, the secondary inlet rectifying surface 912 is convexly curved.
Furthermore, the primary outlet rectifying surface 921 is shaped in a form of a curved surface instead of the form of the flat surface. Specifically, the primary outlet rectifying surface 921 is curved. Furthermore, a center of curvature of the primary outlet rectifying surface 921 is located at an inside of the bypass portion 40, and the primary outlet rectifying surface 921 is convexly curved.
Also, like the primary outlet rectifying surface 921, the secondary outlet rectifying surface 922 is shaped in a form of a curved surface. Specifically, like the primary outlet rectifying surface 921, the secondary outlet rectifying surface 922 is convexly curved.
Even in the second embodiment, advantages, which are similar to those of the first embodiment, can be achieved, Furthermore, in the second embodiment, the primary outlet rectifying surface 921 and the secondary outlet rectifying surface 922 are convexly curved. Since the primary outlet rectifying surface 921 and the secondary outlet rectifying surface 922 do not have a sharp corner, the air can more easily flow along the primary outlet rectifying surface 921 and the secondary outlet rectifying surface 922 in comparison to the case where the primary outlet rectifying surface 921 and the secondary outlet rectifying surface 922 are respectively shaped in the form of the flat surface. Therefore, it is possible to limit a decrease in the flow velocity of each of the air, which is discharged from the primary physical quantity measurement passage outlet 501 and the air, which is discharged from the secondary physical quantity measurement passage outlet 502.
Furthermore, the primary inlet rectifying surface 911 and the secondary inlet rectifying surface 912 are convexly curved. Therefore, like the above-described one, it is possible to limit a decrease in the flow velocity of each of the air, which is discharged from the primary physical quantity measurement passage outlet 501, and the air, which is discharged from the secondary physical quantity measurement passage outlet 502.
A third embodiment is the same as the first embodiment except for the configurations of the primary inlet rectifying surface, the secondary inlet rectifying surface, the primary outlet rectifying surface and the secondary outlet rectifying surface.
In the air flow rate measurement device 23 of the third embodiment, the primary inlet rectifying surface 911 is shaped in a form of a stepped surface instead of the form of the flat surface. Furthermore, as shown in
Furthermore, the primary outlet rectifying surface 921 is shaped in a form of a stepped surface instead of the form of the flat surface. The primary outlet rectifying surface 921 has a plurality of steps. Also, like the primary outlet rectifying surface 921, the secondary outlet rectifying surface 922 is shaped in a form of a stepped surface.
Even in the third embodiment, advantages, which are similar to those of the first embodiment, can be achieved. Furthermore, in the third embodiment, each of the primary outlet rectifying surface 921 and the secondary outlet rectifying surface 922 is shaped in a form of a stepped surface. With this configuration, small vortexes are generated in the flow along the primary outlet rectifying surface 921 and the flow along the secondary outlet rectifying surface 922. Since generation of relatively large vortexes is suppressed by the generation of the small vortexes, it is possible to reduce the pressure loss of the air, which is discharged from the primary physical quantity measurement passage outlet 501, and the pressure loss of the air, which is discharged from the secondary physical quantity measurement passage outlet 502. Thus, the pressure difference between the air, which is discharged from the primary physical quantity measurement passage outlet 501, and the air, which flows along the primary housing lateral surface 51, in the direction along the primary housing lateral surface 51 is reduced. Furthermore, the pressure difference between the air, which is discharged from the secondary physical quantity measurement passage outlet 502, and the air, which flows along the secondary housing lateral surface 52, in the direction along the secondary housing lateral surface 52 is reduced, Therefore, the disturbance of the air, which flows along the primary housing lateral surface 51, by the air, which is discharged from the primary physical quantity measurement passage outlet 501, is limited, and the disturbance of the air, which flows along the secondary housing lateral surface 52, by the air, which is discharged from the secondary physical quantity measurement passage outlet 502, is limited.
Furthermore, each of the primary inlet rectifying surface 911 and the secondary inlet rectifying surface 912 is shaped in the form of the stepped surface. Therefore, like the above-described one, it is possible to reduce the pressure loss of the air, which flows from the physical quantity measurement passage inlet 500 to the primary physical quantity measurement passage outlet 501 and the secondary physical quantity measurement passage outlet 502 through the physical quantity measurement passage 50. Thus, it is possible to reduce the pressure loss of the air, which is discharged from the primary physical quantity measurement passage outlet 501, and the pressure loss of the air, which is discharged from the secondary physical quantity measurement passage outlet 502. As a result, the disturbance of the air, which flows along the primary housing lateral surface 51, by the air, which is discharged from the primary physical quantity measurement passage outlet 501, is limited, and the disturbance of the air, which flows along the secondary housing lateral surface 52, by the air, which is discharged from the secondary physical quantity measurement passage outlet 502, is limited.
The present disclosure is not necessarily limited to the above embodiments, and the above embodiments may be suitably modified. Further, in each of the above embodiments, it is needless to say that the elements constituting the embodiment are not necessarily essential unless explicitly specified as being essential or in principle considered to be essential.
(1) In the above embodiments, the physical quantity sensing device 81 outputs the signal, which corresponds to the temperature of the air flowing in the physical quantity measurement passage 50. However, the physical quantity sensing device 81 should not be limited to the above configuration where the physical quantity sensing device 81 outputs the signal, which corresponds to the temperature of the air flowing in the physical quantity measurement passage 50, and the physical quantity sensing device 81 may be configured to output a signal, which corresponds to a relative humidity of the air flowing in the physical quantity measurement passage 50. Furthermore, the physical quantity sensing device 81 may output a signal, which corresponds to a pressure of the air flowing in the physical quantity measurement passage 50.
(2) In the above embodiments, the primary inlet inner surface 61, the secondary inlet inner surface 62, the primary outlet inner surface 71 and the secondary outlet inner surface 72 are respectively shaped in the form of the flat surface. However, the primary inlet inner surface 61, the secondary inlet inner surface 62, the primary outlet inner surface 71 and the secondary outlet inner surface 72 are not necessarily respectively shaped in the form of the flat surface but may be respectively shaped in a form of a curved surface or a form of a stepped surface.
(3) In the above embodiments, the primary physical quantity measurement passage outlet 501 is formed at the primary housing lateral surface 51, and the secondary physical quantity measurement passage outlet 502 is formed at the secondary housing lateral surface 52. Alternatively, the primary physical quantity measurement passage outlet 501 may be formed at the primary housing lateral surface 51, but the secondary physical quantity measurement passage outlet 502 may not be formed at the secondary housing lateral surface 52. Furthermore, the secondary physical quantity measurement passage outlet 502 may be formed at the secondary housing lateral surface 52, but the primary physical quantity measurement passage outlet 501 may not be formed at the primary housing lateral surface 51.
(4) In the above embodiments, the number of the primary physical quantity measurement passage outlet 501 is one, and the number of the secondary physical quantity measurement passage outlet 502 is one. However, the number of the primary physical quantity measurement passage outlet(s) 501 and the number of the secondary physical quantity measurement passage outlet(s) 502 should not be respectively limited to one and may be changed to two or more.
(5) In the above embodiments, the number of physical quantity measurement passage inlet 500 is one. However, the number of the physical quantity measurement passage inlet(s) 500 is not necessarily limited to one and may be changed to two or more. Furthermore, in the above embodiments, the physical quantity measurement passage inlet 500 is shaped in a form of an elongated rectangle. However, the shape of the physical quantity measurement passage inlet 500 is not necessarily limited to the form of the elongated rectangle and may be changed to a form of a polygon, a form of a circle or a form of an ellipse.
(6) Furthermore, in the above embodiments, each of the primary outlet rectifying surface 921 and the secondary outlet rectifying surface 922 is shaped in the form of the triangle. The shape of each of the primary outlet rectifying surface 921 and the secondary outlet rectifying surface 922 should not be limited to the form of the triangle and may be changed to a form of a polygon. For example, as shown in
(7) In the above embodiments, the circuit board 76 is opposed to each of the primary physical quantity measurement passage outlet 501, the secondary physical quantity measurement passage outlet 502, the primary inlet inner surface 61 and the secondary inlet inner surface 62. However, the circuit board 76 is not necessarily opposed to each of the primary physical quantity measurement passage outlet 501, the secondary physical quantity measurement passage outlet 502, the primary inlet inner surface 61 and the secondary inlet inner surface 62.
For example, as shown in
Furthermore, for example, the circuit board 76 may be arranged in the physical quantity measurement passage inlet 500 such that the circuit board 76 is opposed to the primary inlet inner surface 61 and the secondary inlet inner surface 62, and the circuit board 76 is not opposed to the primary physical quantity measurement passage outlet 501 and the secondary physical quantity measurement passage outlet 502.
(8) It is possible to provide a combination of the airflow rate measurement device 21 of the first embodiment and the air flow rate measurement device 22 of the second embodiment. For example, the primary outlet rectifying surface 921 may be shaped in the form of the flat surface, and the secondary outlet rectifying surface 922 may be shaped in the form of the curved surface. Furthermore, It is possible to provide a combination of the air flow rate measurement device 21 of the first embodiment and the airflow rate measurement device 23 of the third embodiment. For example, the primary outlet rectifying surface 921 may be shaped in the form of the flat surface, and the secondary outlet rectifying surface 922 may be shaped in the form of the stepped surface. Furthermore, It is possible to provide a combination of the air flow rate measurement device 21 of the second embodiment and the air flow rate measurement device 23 of the third embodiment. For example, the primary outlet rectifying surface 921 may be shaped in the form of the curved surface, and the secondary outlet rectifying surface 922 may be shaped in the form of the stepped surface.
(9) In the above embodiments, the pipe extension 112 is shaped in the cylindrical tubular form. However, the pipe extension 112 is not necessarily shaped in the cylindrical tubular form. For example, the pipe extension 112 may be shaped in another tubular form, such as a polygonal tubular form.
(10) In the above embodiments, the holding portion 31 is shaped in the cylindrical tubular form. However, the holding portion 31 is not necessarily shaped in the cylindrical tubular form. For example, the holding portion 31 may be shaped in another tubular form, such as a polygonal tubular form.
(11) In the above embodiments, the connector cover 34 extends from the radially inner side toward the radially outer side of the holding portion 31. However, the connector cover 34 does not necessarily extend from the radially inner side toward the radially outer side of the holding portion 31. For example, the connector cover 34 may extend in the axial direction of the holding portion 31.
(12) In the above embodiments, the flow rate measurement sub-passage 44 is the passage that is branched from the middle of the flow rate measurement main passage 43. However, the flow rate measurement sub-passage 44 is not necessarily limited to the passage that is branched from the middle of the flow rate measurement main passage 43. For example, instead of communicating the flow rate measurement main passage 43 with the flow rate measurement main passage outlet 432, the flow rate measurement sub-passage 44 may be communicated with the flow rate measurement main passage outlet 432 such that the flow rate measurement main passage 43 and the flow rate measurement sub-passage 44 form one flow passage.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2019-161245 | Sep 2019 | JP | national |
This application is a continuation application of International Patent Application No. PCT/JP2020/033287 filed on Sep. 2, 2020, which designated the U.S. and claims the benefit of priority from Japanese Patent Application No. 2019-161245 filed on Sep. 4, 2019. The entire disclosures of all of the above applications are incorporated herein by reference.
| Number | Date | Country | |
|---|---|---|---|
| Parent | PCT/JP2020/033287 | Sep 2020 | US |
| Child | 17666119 | US |
