JPH0654253B2 - Intake passage with air flow meter - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an intake passage of an engine, and more specifically,
The present invention relates to the structure of an intake passage provided with a heating resistor type air flow meter.

[Conventional technology]

2. Description of the Related Art In the field of engines, a heating resistor type air flow meter using a heating wire has been widely put into practical use as an intake sensor for fuel control.

This kind of air flow meter is disclosed in, for example, JP-A-58-26221 and JP-A-59-190624, and a sub-flow passage is provided in a wall portion of a body having an intake passage (main flow passage). To form a heat ray element in this sub-flow path, or recently, to form an L-shaped sub-flow path (pipe line) in the main flow path and to incorporate the heat-ray element in this sub-flow path. Things are proposed.

Of these, the latter L-shaped sub-channel type is oriented in the flow direction of the main channel from the inlet of the sub-channel to the middle of the channel, and the main channel is bridged across the main channel from the middle of the channel to the outlet. The whole exhibits an L-shaped conduit. The inlet and outlet of the sub-flow passage communicate with the main flow passage. In this way, the sub-flow passage provided in the main flow passage has a smaller wall thickness and a smaller and lighter intake body than the system in which the sub-flow passage is provided in the wall portion of the main flow passage itself. It has possible advantages. The L-shaped sub-flow channel type is also applied to the embodiment of the present invention, and therefore, it should be referred to.

[Problems to be Solved by the Invention]

By the way, the heating resistor type air flow meter is desired to have high measurement accuracy.

One of the factors that hinder the improvement of the air flow rate measurement accuracy is that a swirling flow occurs in the main flow path, which causes turbulent flow near the outlet of the sub flow path, making the air discharge state of the sub flow path unstable. Can be mentioned. Particularly, in the case where the above-mentioned L-shaped sub-flow path is provided in the main flow path, the flow in the main flow path tends to be disturbed by the sub-flow path. In the method of providing the L-shaped sub-flow channel in the main flow channel, the main flow channel and the sub-flow channel are integrally molded by die casting, but when the molding is performed, the sub-flow channel exhibits an L-shape, so that a part of the hot water is melted. There is also a problem that the flow tends to be poor and that nests are likely to occur in the sub-flow passage wall portion.

A second cause of hindering the accuracy of flow rate measurement is that there are variations in the products of Slotted Body, which usually have a main flow path and a sub flow path. The air flow measurement accuracy is ±
It is said that the error is suppressed within the range of 3.5%, and the product which is certified as defective in accuracy at the product test stage cannot be used.

The present invention has been made in view of the above points, and its main object is to improve the measurement accuracy of a heating resistor type air flow meter, and secondarily, to provide an intake air device equipped with this kind of air flow meter. It is intended to improve the product flow by improving the flow of hot water for die casting in the passage.

[Means for Solving the Problems]

The present invention takes the following means to achieve the above object.

The means for solving the problems of the present invention will be described below with reference to the reference numerals of the embodiment of FIG. 1 in order to facilitate understanding of the explanation.

That is, the first problem solving means includes, as the intake passage 1 of the engine, the main flow path 2 and the sub flow path 3 in which the heating resistor 30 for measuring the air flow rate is arranged. Located in Road 2 and at its entrance 3-1
From the middle of the flow path to the flow direction of the main flow path 2, and from the middle of the flow path to the outlet 3-2 across the main flow path 2 in the shape of a bridge, the whole exhibits an L-shaped conduit. Outer wall surface 3 facing upstream of the main flow path 2 out of 3
d and the L-shaped inner curved outer wall surfaces 3d and 3e that intersect with the outer wall surface 3e and the inner wall surface 2a of the main flow passage 2, these inner curved outer wall surfaces 3d and 3e, and the main flow passage inner wall surface 2a A plate-shaped rib 11 that is integrally connected to the main flow path 2 is arranged in parallel or substantially parallel to the main flow path 2.

The second means for solving the problem is, as an intake passage of the engine, a main flow path 2 and a sub flow path 3 in which a heating resistor 30 for measuring an air flow rate is arranged (the sub flow path is other than the L-shaped system, for example, a main flow (Which may be provided on the wall portion of the road body itself), a mechanism 12 for variably adjusting the flow passage resistance by changing the cross-sectional area of the passage in the sub flow passage 3 is attached. Become.

The plate-shaped rib 11 of the first problem solving means and the sub-flow path resistance adjusting mechanism 12 of the second problem solving means may be combined, and this will be referred to as a third problem solving means.

[Action]

According to the first problem solving means, the rib 1 provided between the wall portions 3d and 3e of the L-shaped sub flow passage 3 and the inner wall 2a of the main flow passage 2 is provided.
Since 1 is arranged in parallel or almost parallel to the flow direction of the main flow path 2, the main flow path 2 flowing near the installation position of the sub flow path 3
The air flows along the rib 11. That is, the rib 11
Rectifies the air in the main flow path. Therefore, turbulent flow generation in the vicinity of the outlet 3-2 of the L-shaped sub-passage 3 is prevented, the discharge of the flow at the sub-passage outlet 3-2 is made smooth, and the air flow passing through the sub-passage 3 is prevented. It can be made smooth and the disturbance fluctuation of the output of the heating resistor can be suppressed.

Further, in the present problem solving means, when the main flow path 2 and the sub flow path 3 are integrally die-cast, the inner curved wall portions 3a and 3e of the L-shaped sub flow path 3, which has been conventionally considered to have a bad flow of hot water, are used.
Since the hot water is guided straight by the flow of hot water from the direction of the arrow X through the mold space for forming the ribs 11, the hot water is guided to the inner curved wall portions 3a and 3e sufficiently and smoothly to prevent the formation of porosity. To prevent. In the prior art, since the rib 11 does not exist, the inner curved wall portions 3a and 3e of the sub-flow passage 3 have the bridge portion 3c of the sub-flow passage and the outer curved wall portion 3f of the sub-flow passage 3.
Although the hot water is guided from the side, since there are corners 3g and details in the inner curved wall portions 3a and 3e, there is no means for guiding the hot water straightly. Was bad.

Next, according to the second problem solving means, a mechanism for changing the passage cross-sectional area of the sub-flow passage 3 (for example, an adjust screw).
Then, the flow path resistance is variably adjusted.

As a result, the air flow velocity of the sensor section (heating resistor disposition section) in the sub-flow path 3 can be adjusted arbitrarily. Therefore, even if the output of the heat ray element varies, it can be controlled to some extent through the variable adjustment of the sub-flow passage resistance, and even if the intake passage body (for example, slot body) is out of the control range, the flow passage resistance is changed. It can be controlled within the control range by operating the adjustment mechanism.

The third problem solving means can expect the actions of both the first and second problem solving means, and can further improve the accuracy of the air flow rate.

〔Example〕

 An embodiment of the present invention will be described with reference to the drawings.

FIG. 1 is a vertical sectional view showing an embodiment of the present invention.
Is a slot body, 2 is a main flow path, 3 is a sub flow path, and 4 is a slot valve.

The slot body 1 has a main flow path 2 and a sub flow path 3 inside. The sub-flow path 3 has an L-shaped conduit as will be described later, and is arranged upstream of the throttle valve 4.

The slot body 1 has a main flow path 2 at its inlet portion 5.
Is formed into a round or bell mouth shape so that the flow of the stream smoothly contracts. The inlet portion 5 is provided with an annular step 5a, and the mesh 6 is fixed to the step 5a. The mesh 6 is pressed from above by a snap ring 7 so as not to move. Further, the outer peripheral edge of the mesh 6 is fixed by caulking metal so that the mesh does not come apart.

The diameter of the main flow path 2 is sharply narrowed in the vicinity of the outlet 3-2 of the sub flow path 3 (this throttle is indicated by reference numeral 8). The diameter from the inlet portion 5 of the main flow path 2 to the throttle 8 does not change. Also,
The inner diameter of the main flow passage 2 after being throttled does not change until the downstream of the slottle valve 4.

Here, the configuration of the sub flow path 3 will be described.

The sub flow path 3 is located in the main flow path 2 and has an inlet 3-1.
From the middle of the flow path to the outlet 3-2 (this flow path is referred to as 3b) is the bridge from the middle of the flow path to the middle of the flow path (this flow path is referred to as 3a). It exhibits an L-shaped conduit which is entirely cylindrical. FIG. 3 is a view of the slot body 1 from above, showing the flow path portion 3 of the sub flow path 3.
b crosses the center of the main flow path 2.

In this embodiment, the inner diameter of the flow passage portion 3a of the sub flow passage 3 is φ1.
0 mm, the inner diameter of the flow path portion 3b is φ11 mm, and the flow path portions 3a, 3
b are orthogonal to each other.

The inlet 3-1 of the sub-channel is located 13 mm downstream from the mesh 6 provided at the inlet 5 of the main channel, and the sub-channel 3 is eccentric to the main channel 2 by 20 mm. The sub-flow passage inlet 3-1 is die cast, and its end face is formed into a rounded shape (indicated by reference numeral 9).

A part 3a 'of the flow path portion 3a of the sub flow path 3 has a bulge partially, and a heating resistor (hereinafter referred to as a heat wire element) 30 is arranged at this position. The hot wire element 30 is fixed and held by a damage preventing type hot wire module 10 in which an end portion of the hot wire element is integrally covered with a mold, and the hot trowel module 10 is fitted on the wall portion of the slot body 1.

The outlet 3-2 of the sub-flow passage 3 is formed by cutting out one end of the pipe wall of the flow passage portion 3b in a half-split shape (semicircular cross-section). The cut-out opening 3-2 is the slot valve 4 Side, that is, the downstream side of the main flow path 2. By notching the outlet 3-2 in this way, as shown in FIG. 4 (FIG. 4 is a sectional perspective view near AA in FIG. 1), a part 3c of the pipe wall of the flow path step 3b. Has an eaves shape with a semi-circular cross section, and this pipe wall portion 3c has an outlet 3-
It covers the upper side of 2 and plays a role of a wind barrier of the outlet 3-2 with respect to the air flow of the main flow path 2. Further, one end of the tube wall portion 3c is connected to the inner wall of the slot body 1.

Reference numeral 11 denotes a plate-shaped rib that is an essential part of the first problem solving means of the present invention, and is an outer wall surface facing the upstream side of the main flow path 2 of the pipe wall 3c of the flow path portion 3b of the L-shaped sub flow rate 3. (Indicated by reference numeral 3d) and an outer wall surface 3e on the side of the flow path portion 3a which is orthogonal to the outer wall surface 3d and is connected to an L-shaped inwardly curved outer wall surface, and also to the inner wall surface 2a of the main flow path that opposes the outer wall surface 3e. It is cast and formed integrally with the slot body 1 so as to be connected.

The rib 11 is arranged in parallel with the flow of the main flow path 2, and its cross section is formed in a shape that gradually expands from the upstream side of the main flow path to the downstream side.

In the inner diameter of the flow passage portion 3b, the stroke adjuster 12 is arranged coaxially with the flow passage portion 3b on the outlet 3-2 side. This Ajist Skull 12
Is fitted in a screw hole 13 provided in the wall portion of the slot body 1, and the area of the sub-flow path outlet 3-2 having a semicircular cross section can be changed by performing a stroke operation from the outside. The flow path resistance of the sub flow path 3 can be arbitrarily adjusted by changing the area of -2. Note that the adjusted plug 14 is press-fitted into the screw hole 13, making it difficult for an amateur to readjust in the market.

Here, other related parts of the slot body 1 will be described.

A flat surface 2 bg is formed on a part of the outer wall surface of the slot body 1.
f is formed, and the hot wire module 10 is disposed on the flat surface 2b.

The slot valve 4 is a pressed product of an Al plate material, and the outer periphery is not cut. Reference numeral 15 designates a slottle shaft, which penetrates the inside of the main flow path 2 as shown in FIG. 3 and has a slotter lever mechanism 16 attached to one end thereof, and the other end thereof projects from the outer wall of the slot body 1 as shown in FIG. Tenth
The figure is a cross-sectional view showing the through state of the throttle shaft 15, and the shaft 15 is axially supported by the wall portion of the body 1. A peripheral groove 19 is formed at a portion of the slot shaft shaft 15 extending from the bearing portion 18, a thrust plate 20 is inserted into the peripheral groove 19, and the thrust plate 20 is screwed to the slot body 1. The thrust play of the shaft 15 is determined by the difference in plate thickness between the groove 19 and the thrust plate 20.

Further, as shown in FIG. 1, the throttle valve 4 is
It has a hole 21 so that a certain amount of leakage occurs when it is fully closed.

Reference numeral 22 denotes a flange located at the lower end of the slot body 1, and an end surface 22a of the flange 22 serves as a joint surface with an intake manifold (not shown). The joint surface 22a has a blow-by gas recirculation passage 23 as shown in FIG. A hot water passage 24 and an idle air control (hereinafter abbreviated as IAC) passage outlet 27-2 are provided.

Although not shown, the blow-by gas circulation passage 23 has one end opened to a part of the intake manifold, passes through the joint surface 22a of the intake manifold and the slot body 1, and is penetrated to the slot body 1 to form a slot body. In No. 1, as shown by the dotted line in FIG. 5, it is formed in parallel with the main flow path 2, bends at a right angle in the upstream part of the slottling valve 4, and joins with the main flow path 2 in the upstream part of the slottling valve 4. Of the blow-by gas passage 23, a passage portion 23a parallel to the main passage 2 is formed by die casting and is not processed. Therefore, the passage portion 23a is tapered. In addition, the passage portion 2 perpendicular to the passage portion 23a
3b is processed from the outside of the slot body 1 toward the main flow path 2, and the outside is closed by a plug 25.

The outlet 23c of the blow-by gas passage 23 is opened on the wall surface of the main flow passage, and is opened at a portion which is not shaded by other members when viewed from the upstream of the main flow passage.

A gas bucket is provided between the intake manifold and the joint surface 22a of the slot body 1 to block the ventilation of the blow-by passage and the outside air.

The hot water passage 24 is for guiding hot water in the vicinity of the main flow path 2 of the slot body 1 and in the vicinity of the slot bearing.
As shown in FIG. 2, it is composed of a groove formed by die casting on the flange surface 22a, and is formed by covering one surface of the groove 24 with the upper surface of the intake manifold. It is sealed with a gasket with an O-ring so that it will not come out.

The hot water passage groove 24 has a taper for die casting so that it is formed only by die casting without processing. A hot water outlet and a hot water inlet are opened on the upper surface of the intake manifold, and the hot water discharged from the hot water outlet passes through the hot water passage groove 24 and returns from the hot water inlet to the intake manifold side.

FIG. 7 is a rear view of the slot body 1, in which 26 is a stepper motor type IAC valve, so that the valve element incorporated in the IAC passage in the slot body 1 operates almost perpendicularly to the main flow path 2. It is installed on the slot machine.

8 (a) and 8 (b) show the internal structure of the IAC passage 27, FIG. 8 (b) is a view seen from the direction B in FIG. 8 (a), and 27-1 is the passage inlet, 27-2 is a passage exit. The passage inlet 27-1 is opened at a position upstream of the throttle valve 4 downstream of the throttle 8 in the vicinity of the auxiliary passage outlet 3-2 in the inner wall of the main passage, and the passage outlet 27-2 is provided downstream of the throttle valve 4. It is open.

The IAC passage outlet 27-2 is composed of a groove formed in the manifold joint surface 22a of the flange 22 as shown in FIG. 2, and the fully open surface is covered with the upper surface of the intake manifold to form a part of the passage. A seal between the slot body and the slot body is provided by a gasket 29 that seals the joint surface between the slot body and the intake manifold.

The IAC passage 27 has an inlet 27-1 and an outlet 27-.
At least three right angle bends 27 on the passage between the two.
a, 27b, 27c. Of these, at least one of the right-angled bends is inevitably in communication with the outside due to processing, and this communication is stopped by a plug (not shown).

A valve body 28 is incorporated in a part 27b of the IAC passage 27, and the valve body 28 is controlled to be opened / closed by a stepper motor (IAC valve actuator) 26a according to an idle control signal.

Further, the valve body 28 of the IAC valve is configured to apply a force in the opening direction by the negative pressure of the intake manifold in order to reduce the driving load. The cross section of the upstream side inlet 27-1 of the IAC passage is circular, and the cross section of the downstream side outlet 27-2 is rectangular.

Three intake bolts are fixed to the intake manifold, and the slot body 1 shown in FIG.
A stud bolt is inserted into the three holes 31, 32, 33 of the side flange 22 and tightened with a nut.

Between the intake manifold and the slot body 1
It is fastened via a plastic gasket with an O-ring.

The positions of the three holes 31, 32, 33 on the body side flange are
It is located at a position where a box wrench space of φ20 can be secured from the top and the surface pressure can be made uniform.

According to this embodiment having such a configuration, the ribs 11 and the auxiliary screw 12 for adjusting the auxiliary flow path resistance are particularly used.
The following actions and effects can be expected by using.

When a part of the air flow in the main flow path 2 passes through the sub flow path 3 and the flowing air amount (air flow rate) changes according to the slot opening, the current value of the heat wire element that always tries to maintain a constant temperature. The air flow rate is measured from the change of. At this time, the main flow path 2
When turbulence is generated in the air flow inside, the discharge of air in the sub-flow path 3 becomes unstable, which adversely affects the measurement accuracy, but this is improved by the presence of the ribs 11 as follows. .

That is, since the ribs 11 are arranged in parallel with the main flow path 2, the air in the main flow path 2 passing near the installation location of the sub flow path 3 flows along the ribs 11. In this way, the ribs 11 rectify the air flow in the main flow path and prevent the occurrence of turbulent flow near the outlet 3-2 of the sub flow path 3. Further, in this embodiment, the rib 1
Since 1 has a shape in which the cross-sectional area gradually expands toward the downstream direction, the air flow of the main flow path 2 passes avoiding the sub flow path 3 that crosses in the shape of a bridge as shown by an arrow C in FIG.
In addition to making the air flow in the main flow path 2 smoother,
The sub-flow passage outlet 3-2 is connected to the eave-shaped pipe passage portion 3c of the sub-flow passage 3.
The air in the sub-flow passage can be discharged in an extremely stable state without being further affected by the main flow air flow in the vicinity of the sub-flow passage outlet 3-2.

Further, in the present embodiment, when the main flow path 2 and the sub flow path 3 are integrally formed by die casting, ribs are formed on the inner curved wall portions 3a and 3e of the L-shaped sub flow path 3, which was conventionally considered to have a bad flow of the molten metal. 1
Since the hot water is guided straight by the flow of the hot water from the direction of the arrow X through the mold space of one molding, the inner curved wall portion 3a,
Sufficiently and smoothly introduces hot water to 3e to prevent the formation of cast iron.

Further, the adjusting mechanism such as the adjust screw 12 changes the cross-sectional area of the auxiliary flow path 3 by the stroke.

As a result, the air flow velocity of the sensor section (heat wire element arrangement section) can be controlled. Therefore, the output of the heat ray element 30 can be controlled to some extent, and even a slotted body that is once out of the control range can be brought into the control range by operating the adjust screw.

FIG. 11 shows the characteristic change of the deviation (ΔQ / Q) of the output value of the heat wire element in terms of the air flow rate when the thrust screw 12 is converted into a stroke and moved by 1 mm. A 1 mm shift causes ΔQ / Q to shift by approximately 1% over the entire range from low speed to high speed. This means that adjustment is possible if the width between the maximum value and the minimum value of the characteristic is smaller than the control width.

In this way, most throttle slots can be accommodated within the control range by using the Adjust Screen.

〔The invention's effect〕

As described above, according to the present invention, by providing the rib on the inner curved wall portion of the L-shaped sub-flow path as in the first problem solving means, the air flow in the main flow path is effectively rectified, and the sub-flow path is formed. It is possible to prevent generation of turbulent flow in the vicinity of the outlet, suppress turbulence in output of the heat wire element, and improve air flow measurement accuracy. In addition, the presence of the ribs can improve the flow of molten metal in slotter body casting, which has been a problem in the related art, reduce the cast iron after processing, and improve the product yield.

Further, if the flow path resistance adjusting mechanism of the sub-flow path is used as in the second problem solving means, the accuracy of the air flow rate measurement varies at the stage of product completion, and the accuracy can be controlled even in the case of a defective slot body. It can be shifted inward, and the defect rate is significantly reduced. Therefore, the product cost can be reduced.

[Brief description of drawings]

1 is a longitudinal sectional view showing an embodiment of the present invention, FIG. 2 is a bottom view thereof, FIG. 3 is a plan view thereof, and FIG. 4 is A- of FIG.
FIG. 5 is a front view of the above embodiment, FIG. 6 is a left side view of the same, FIG. 7 is its rear view, and FIG. 8 is a part of its internal structure. FIG. 9 is a partial sectional view showing the right side view, FIG. 10 is a lateral sectional view thereof, and FIG.
The figure is a characteristic diagram of the air flow rate-heat wire element output value deviation characteristic when the thrust screw used in the above embodiment is operated. 1 ... Slot body (intake passage), 2 ... Main flow path,
2a ... Main flow passage inner wall, 3 ... Sub flow passage, 3-1 ... Sub flow passage inlet, 3-2 ... Sub flow passage outlet, 3d, 3e ... L-shaped inner curved outer wall surface, 11 ... Ribs, 12 ... Flow path resistance adjusting mechanism (Adjust Screw), 30 ... Heat wire element.

Claims (5)

[Claims] 1. An intake passage for an engine, comprising a main flow passage and a sub-flow passage for arranging a heating resistor for measuring an air flow rate, the sub-flow passage being located in the main flow passage and having its inlet. From the middle of the flow path to the flow direction of the main flow path, and from the middle of the flow path to the outlet crosses the main flow path in a bridge shape to form an L-shaped conduit as a whole. Between the inner wall surface of the main flow path and the L-shaped inner curved outer wall surface of the outer wall surface facing the upstream side of the main flow path and the outer wall surface intersecting with the outer wall surface, An intake passage with an air flow meter, characterized in that plate-like ribs integrally connected to an inner wall surface are arranged in parallel or substantially parallel to the main flow path. 2. The intake passage with an air flow meter according to claim 1, wherein the rib is formed so that its cross-sectional area gradually increases toward a downstream direction of the main flow passage. 3. The main flow passage according to claim 1 or 2, wherein the outlet of the sub-flow passage is formed by cutting out a part of the sub-flow passage pipe wall surface facing the downstream side of the main flow passage. An intake passage with an air flow meter, which is provided with a mechanism for variably adjusting the outlet area of the sub-passage to adjust the flow passage resistance of the sub-passage in a part of the body of the passage. 4. An air intake passage of an engine, comprising a main flow passage and a sub flow passage for arranging a heating resistor for measuring an air flow rate, and allowing a part of the air in the main flow passage to pass through the sub flow passage. The intake passage with an air flow meter according to claim 1, further comprising a mechanism for variably adjusting a passage resistance by changing a passage cross-sectional area in the sub passage. 5. The intake passage with an air flow meter according to claim 3 or 4, wherein the flow path resistance adjusting mechanism of the sub-flow path is constituted by an adjust screen.