JPH0711438B2 - Air flowmeter with rectifying grid - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial field of application) The present invention relates to an air flow meter used in an internal combustion engine of an automobile, and more particularly to a structure for mounting a rectifying grid for rectifying the flow of air in the vicinity of a flow rate measuring unit. It is about.

(Prior Art) As an air flow meter of this type, there is a conventional one shown in FIGS. In this air flow meter, a rectifying grid 2 is arranged at the air inlet portion 1, and a square frame-shaped holding collar 3 is attached to the outer circumference of the upstream side surface (left side surface in FIG. 6) in the air flow direction. Then, as shown in FIG. 7, the left and right outer sides of the presser collar 3 are placed at the upper and lower two places 4, and the outer surface of the presser collar 3 is caulked so that a part of the housing 5 is caulked. At the same time, the rectifying grid 2 is fixed to the housing 5.
That is, in this case, the rectifying grid 2 is crimped to the inlet portion 1 while being pressed in the downstream direction of the air flow together with the pressing collar 3. In this conventional example, 6 is a vortex generator and 7 is a vortex detector.

(Problems to be Solved by the Invention) In such a conventional air flow meter, the rectifying grid 2 is simply caulked by the pressing collar 3 portion provided on the outer periphery thereof, and the rectifying grid 2 is housed in the housing 5. It is not structured so that it can be directly fixed and supported. Therefore, when the rectifying grid 2 repeatedly receives a large force from the downstream side to the upstream side in the air flow direction due to intake pulsation of the engine, intake air blowback from the engine, or the like, the rectifying grid 2
May be easily deformed in the direction orthogonal to the air flow, that is, in the up / down or left / right direction. Moreover, such deformation makes it impossible to obtain an appropriate rectification effect, or in extreme cases, rectification There was a risk that the lattice 2 would fall off the housing 5.

Configuration of the Invention (Means for Solving the Problems) In order to solve the above-mentioned problems, the present invention provides a rectifying grid in a housing provided with a flow rate measuring unit in the air flow direction upstream of the flow rate measuring unit. At the same time, a structure is adopted in which the tip of a stopper member for fixing the same rectifying grid to the housing penetrates through the eyes of the rectifying grid and is fixed to a part of the housing.

(Operation) The air that has entered the housing is rectified by the rectification grid and then reaches the flow rate measurement unit. During this operation, the rectifying grid is repeatedly subjected to a force that deforms itself due to intake pulsation and blowback of the engine, and this deforming force is fixed by a stop member inserted through the eyes of the rectifying grid so as to fix the rectifying grid to the housing. Accepted.

(Embodiment) An embodiment of the present invention will be described below with reference to FIGS. As shown in FIG. 1, 11 is a housing having a rectangular tubular shape, 12 is an air passage therein, and 12 a are four inner wall surfaces of the air passage 12. 13 is a step formed slightly inside the upstream side end (left end in FIG. 1) of the housing 11 in the air flow direction, and 14 is a rectifying grid having a square front shape attached so as to engage with the step 13. In addition, a large number of eyes 14a are formed in a honeycomb shape and have a function of rectifying the air flowing into the air passage 12.

Reference numeral 16 is a holding collar having a rectangular frame shape (FIG. 3) for pressing and holding the flow regulating grid 14 against the step 13, and the inside thereof is an air introduction passage 16a. In addition, this presser collar 1
As shown in FIG. 2, the outer shape of 6 is slightly larger than the outer shape of the rectifying grid 14. Further, the holding collar 16 is engaged with the step 15 corresponding to the upstream end surface of the rectifying grid 14, and the upstream end surface of the pressing collar 16 itself is the housing 11.
It almost coincides with the open end of.

As shown in FIGS. 3 to 5, reference numeral 17 denotes four guide surfaces formed inside the upper and lower horizontal frame portions 18 and the left and right vertical frame portions 19 of the presser collar 16, all of which are downstream of the air introduction passage 16a. So that they converge toward each other, and the downstream edge is connected to the upstream edge of the inner wall surface 12a of the housing 11 without a step (first
Figure) It is formed in a smooth arc shape. As shown in FIG. 2, the inner ends of the upper and lower horizontal frame portions 18 of the presser collar 16 are located on the upper and lower upstream side surfaces of the rectifying grid 14, and the left and right vertical frame portions 19 are respectively.
Similarly, the inner ends are in contact with the upstream side surfaces on both left and right sides.

As shown in FIGS. 1 and 3, reference numeral 21 denotes a pair of upper and lower mounting recesses formed by notching the upper and lower horizontal frame portions 18 of the presser collar 16 from the outside.
Is a screw insertion hole in contact with the bottom wall of each mounting recess 21,
It corresponds to any one of a large number of eyes 14a located above and below the rectifying grid 14.

As shown in FIG. 1, 23 is each mounting recess 21 of the presser collar 16.
Correspondingly, there are four screw holes (only one is shown) formed on the surface of the step 13 on the downstream side of the rectifying grid 14. Reference numeral 24 is a set screw as a stop member that is inserted into each mounting recess 21 of the presser collar 16 from the outside, and each tip has a screw insertion hole.
It is screwed into the screw hole 23 of the housing 11 through 22 and the eye 14a of the rectifying grid 14.

Therefore, the rectifying grid 14 and the pressing collar 16 are fixed to the housing 11 by the four set screws 24. Further, in this case, the four set screws 24 have the eyes 14a through which they are inserted.
When the rectifying grid 14 receives a deforming force due to the influence of intake pulsation of the engine or the like, the rectifying grid 14 acts to support the force and prevent the deformation.

Reference numeral 25 is a pair of left and right insertion pins integrally formed with the left and right vertical frame portions 19 of the presser collar 16, and projects from the guide surface 17 of each vertical frame portion 19 in the downstream direction of air. Each of these pins 25 has a columnar shape, and about half of the thickness of each pin 25 is swelled in the air introduction passage 16a. Further, these pins 25 are engaged with one of the eyes 14a located on both left and right sides of the rectifying grid 14 in a state where the pressing collar 16 is in contact with the upstream side surface of the rectifying grid 14. Then, similarly to the set screw 24, when the rectifying grid 14 receives a deforming force, it supports the deforming force.

As shown in FIG. 1, 26 is a vortex generator for generating Karman vortices standing upright in the air passage 12, 27 is a measuring portion provided on the downstream side surface of the vortex generator 26, It is for detecting the number of Karman vortices according to the flow rate of the air flowing inside 12. The vortex generator 26 and the measuring unit 27 form a flow rate measuring unit. Reference numeral 28 denotes a circuit room provided on the housing 11, 29 denotes a processing circuit provided in the circuit room 28, for processing a signal according to the number of Karman vortices detected by the measuring unit 27. . In addition, 30 is a vortex generator 26
The intake air temperature sensor is provided at a downstream position of, and is located at a position that does not interfere with the generation of Karman vortices. Reference numeral 31 is a bypass air passage.

Now, in the air flow meter configured as described above, the air flows from the air introduction passage 16a in the holding collar 16 through the rectifying grid 14 into the air passage 12 in the housing 11.
When this air reaches the vortex generator 26, Karman vortices are generated on the downstream side of the vortex generator 26, and the number thereof is detected by the measuring unit 27. The detection signal is processed by the processing circuit 29 in the circuit room 28 and output from the connector (not shown).

When detecting the flow rate of air in this way, the rectifying grid 14 serves to rectify the air entering the air passage 12 from the air introducing passage 16a. Further, in this case, since the rectifying grid 14 is exposed to the flow of the intake air, it is constantly subjected to a force that tends to deform due to the intake air pulsation of the engine, the blowback of the intake air, the intake air drift, and the like.

However, in this case, the rectifying grid 14 is not easily deformed in this embodiment.

That is, the rectifying grid 14 is fixed to the housing by the presser collar 16.
Not only is it held by being pressed against the step 13 of 11, but the four set screws 24 are fitted into the four eyes 14a of the rectifying grid 14 so that the tips of each set screw 24 are connected to the step 13 It is screwed and fixed to the part. Since the set screw 24 is engaged with the eye 14a of the rectifying grid 14 which is inserted through these, when the rectifying grid 14 receives a deforming force due to the influence of engine intake pulsation, etc., the force is retained by the pressing collar 16. Not only force but also set screw 24
Are also supported by engaging the eyes 14a of the flow control grid 14. Further, since the rectifying grid 14 has a certain width in the length direction of the set screw 24 and the eyes 14a also have the same width, the deforming force applied to the rectifying grid 14 is set by the set screw 24.
In the portion corresponding to, the eye 14a is supported over the entire width direction, and as a result, deformation in the vertical and horizontal directions is prevented.

Further, 4 of the presser collar 16 is attached to the eye 14a of the rectifying grid 14.
Since the individual insertion pins 25 are engaged, the rectification grid 14 is also prevented from being deformed by these insertion pins 25. That is, the presser collar 16 is fixed to the housing by the set screw 24.
Since the insertion pins 25 are firmly fixed to 11 and the insertion pins 25 are formed integrally with the pressing collar 16, these insertion pins 25 are also held in a stable state in which they cannot be moved. Therefore, these pins 25 also act to prevent deformation of the rectifying grid 14 by engaging with the eyes 14a when the rectifying grid 14 receives a deforming force.

Further, in the above-described embodiment, the four guide surfaces 17 inside the presser collar 16 are formed in a smooth arc shape so that the downstream edges thereof are connected to the inner wall surface 12a of the air passage 12 of the housing 11 without any step. Air introduction passage 16a inside the collar 16
It is possible to reduce the loss of the flow from the air passage 12 to the air passage 12, and also to increase the air rectification effect by the rectification grid 14.
As a result, the generation of Karman vortices can be stabilized.

The holding collar 16 in the above embodiment is not always necessary. In the above embodiment, the rectifying grid 14
Although four setscrews 24 are used as the stop members for fixing the to the housing 11, the stop members may be any ones that can be inserted into the eyes 14a of the flow control grid 14, so that instead of the set screws 24, a rod-shaped stop screw is used. The tip may be fixed to a part of the housing 11 by using a pin, and the number is not limited to four. Further, when the pressing collar 16 is provided, the insertion pin 25 does not need to be formed integrally with the pressing collar 16 and may be a separate body.

Effects of the Invention As described in detail above, the present invention can prevent deformation of the rectification grid due to engine intake pulsation, intake air blowback, etc., increase the air rectification effect by the rectification grid, and eventually stabilize the flow rate measurement. be able to.

[Brief description of drawings]

FIG. 1 is a vertical cross-sectional view of an air flow meter embodying the present invention, FIG. 2 is a front view of the same from the air introduction passage side of the air flow meter, and FIG. 3 is a front view of only the holding collar.
FIG. 4 is a sectional view taken along the line AA of FIG. 3, and FIG.
FIG. 6 is a vertical sectional view showing a conventional air flow meter, and FIG. 7 is a front view seen from the inlet side thereof. Housing …… 11, rectifying grid …… 14, eyes …… 14a, vortex generator …… 26.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Ri Koike 1-1, Kariya, Aichi Prefecture, Nihon Denso Co., Ltd. Within the corporation

Claims (5)

[Claims] 1. A rectifying grid (14) is provided on the upstream side of the flow rate measuring section (26, 27) in the air flow direction inside a housing (11) having the flow rate measuring section (26, 27) therein. Installation of a rectification grid in which the tip of a stopper member for fixing the rectification grid (14) to the housing (11) penetrates the eye (14a) of the rectification grid (14) and is fixed to a part of the housing (11) An air flow meter having a structure. 2. The stop member is four set screws inserted from the upstream side in the air flow direction with respect to the flow straightening grid (14), and the tips of these set screws (24) are straightening grid (14). The air floater having the structure for mounting a rectifying grid according to claim 1, wherein the air floater is screwed into the housing (11) through the eye (14a). 3. A holding collar (16) for holding the straightening grid (14) in the air flow direction upstream side is arranged, and the stop member surrounds the holding collar (16) from the upstream side thereof. An air flow meter having a structure for mounting a rectification grid according to claim 1, wherein the air flow meter is inserted through the frame section (18, 19) of the rectification grid (14). 4. The presser collar (16) is provided with a plurality of insertion pins (25) projecting to the downstream side in the air flow direction and engaged with the eyes (14a) of the rectifying grid (14). An air flow meter having a structure for mounting a rectifying grid according to claim 3. 5. The presser collar (16) is internally provided with a guide surface (17).
The guide surface (17) is smooth so that the downstream edge of the guide surface (17) connects with the inner wall surface (12a) of the air passage (12) in the housing (11) without any step. An air flow meter having a structure for mounting a rectifying grid according to claim 1, wherein the air flow meter is formed in an arc shape.