JPH0613985B2 - Mounting structure of gas flow measuring device - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a mounting structure of a gas flow rate measuring device for measuring a flow rate of gas, for example, air flowing in a flow path pipe.

[Conventional technology]

2. Description of the Related Art Conventionally, in an engine for a vehicle, an air flow rate measuring device for measuring the air amount is mounted in order to supply the engine with a fuel amount corresponding to the air amount sucked into the engine.

In recent years, various measuring devices such as a vane type and a heating wire type Karman vortex type have been developed for vehicles, and some of them are actually used.

In the vane type air flow rate measuring device, for example, as shown in Japanese Patent Publication No. 59-12865, a rectangular vane (cushion plate) that is set to be rotatable across a rectangular channel cross section is a It was rotated by receiving the pressure difference caused by the flow, and the air flow rate was measured from this rotation angle.

However, in the vane type air flow measuring device,
As the air flow rate increases, the opening of the vane increases, and the vertical component of the pressure receiving surface where the vane receives pressure from the air flow decreases. Since the ratio transmitted to the vane side is reduced, the change in the opening of the vane, that is, the change in the rotation angle of the vane with respect to the flow rate change in the high air flow rate range is extremely small. There was a problem that it was not enough.

In addition, in the configuration disclosed in the above publication, in order to suppress the vane from vibrating due to the pulsation of the air flow and the vane from excessively changing due to a rapid change in the air flow rate, a fan-shaped fan that is fed to the side of the air passage is provided. The chamber is formed, the damping plate and the vane that swirl the chamber are connected, and the air damping function of the chamber and the damping plate acts on the vane. However, the size (volume) of this fan-shaped chamber cannot be made very small in order to make its air damping function sufficient, and it is set so as to squeeze out to the side of the air passage. Therefore, there is a problem that the device itself becomes large and there are many restrictions when mounted on the vehicle, that is, the mountability on the vehicle is poor.

In view of such problems, the present applicant has filed Japanese Patent Application No. 60-259.
As in No. 136, a gas flow path through which the measured gas flows in the axial direction, and a movement set in the gas flow path in a state where linear movement is possible along the flow direction of the measured gas. A member, the gas flow path formed inside, and a flow path tube formed so that the flow path cross-sectional area increases along the flow direction of the gas to be measured at least in the moving range of the moving member; An axis extending from the member along the flow direction of the gas to be measured, fixedly set in the gas flow path with the flow path tube, and supporting the axis in a movable state according to the movement of the moving member. A bearing, a pressing member that exerts a pressing force on the moving member in a direction opposite to the flow direction of the gas to be measured, a conversion unit that converts the displacement amount of the shaft into an electric signal, and one end is closed by the moving member. Of the measured gas with the other end open A first cylinder extending in the direction of flow, fixedly set in the gas flow path with the flow path pipe, closed at one end and open at the other end, and through a minute gap with the first cylinder. A small gas flow rate measuring device having a second cylinder to be fitted with is applied.

[Problems to be solved by the invention]

By the way, in recent years, there has been a great demand for miniaturization of vehicle engines, and various attempts have been made not only to reduce the size of each component of the engine itself, but also to reduce the number of components and to integrate each component. There is. Generally, a gas flow rate measuring device is arranged downstream of a box body such as an air cleaner or an air intake duct.
Since the vane type air flow measuring device disclosed in Japanese Patent Laid-Open No. 9-12865 has a large shape and a complicated shape, even if the air flow measuring device is directly attached to the box body in order to meet the demand for downsizing of the engine. However, it was very difficult to realize it, and it was absolutely necessary to provide piping such as a rubber hose for connecting the box body and the air flow rate measuring device.

An object of the present invention is to make the engine compact by directly mounting a small gas flow rate measuring device such as Japanese Patent Application No. 60-259136 on the box body.

[Means for solving problems]

Therefore, in the present invention, there is provided a mounting structure of a gas flow rate measuring device, wherein an air outlet end portion of a box body in which air drawn into a vehicle engine flows is connected to an air inlet end portion thereof, wherein the gas is The flow rate measuring device has a flow path tube, and the flow path tube has a plurality of housings which are bonded and sealed to each other at a bonding portion, and each of the bonding portions raises an outer peripheral portion of each housing to increase a wall thickness. The portion of the housing adjacent to the joint portion has a cylindrical surface having a diameter smaller than that of the joint portion, and a stay is provided on the fixed surface of the gas flow rate measuring device in the box body. A holder is attached to the stay, and the holder has a central portion formed in an arc shape in contact with a portion of the housing having the cylindrical surface, and extends along the circumferential direction of the holder. End is front Note It is bent according to the shape of the joint so as to wrap the joint of each housing, the air outlet end of the box and the air inlet end of the gas flow rate measuring device is a grommet. The gas flow rate measuring device is attached via the elastic deformation of the grommet.

[Action]

Since the joints of each housing are wrapped by the ends along the circumferential direction of the holder, the force that separates the joints also acts on the holders. Deterioration and separation can be prevented.

Further, by coupling the holder and the joint, it is possible to prevent axial displacement and rattling between the holder and the housing, and the mounting is further strengthened. Also, the gas flow rate measuring device is connected to the box body via a grommet, but this grommet needs to have a sealing action and a comparatively weak coupling force (the box body and the gas flow rate measuring device are firmly held by a holder. To attach),
The structure is simplified.

Further, since the axial displacement and rattling of the holder and the housing can be prevented, the grommet seal will not be deteriorated by the vibration of the vehicle.

〔Example〕

An embodiment of a gas flow rate measuring device to which the mounting structure according to the present invention is applied will be described below with reference to the drawings.

The measuring device shown in FIGS. 5 to 9 shows a configuration of an embodiment of a gas flow measuring device for measuring a flow rate of air drawn into a vehicle engine, particularly an automobile engine. The flow path pipe 1 constitutes a part of an intake pipe of an engine (not shown), and is composed of three housings 1a, 1b, 1c, and the cross-sectional shape of each of the housings 1a, 1b, 1c along the air flow direction. Is circular, and the housings 1a, 1b, 1c are linearly arranged so as to have the same central axis. An air passage 2 through which air flows in the axial direction is formed inside the passage pipe 1 constituted by the housings 1a, 1b and 1c. It should be noted that the housings 1a, 1b, 1c are securely sealed at the joints 1d, 1e so that there is no ventilation to the outside, and the housings 1a, 1b, 1c are sealed.
When c is made of a resin material, it is sealed by adhesion or welding. Further, the joint portions 1d and 1e are formed by raising the outer peripheral portion of the housing to increase the wall thickness, and firmly connect the housings.

In the air flow path 2, there is provided a moving member 3 made of a resin material that is set so as to be linearly movable along the air flow direction. On the other hand, it has a convex shape on the upstream side, and the surface of the convex shape forms a smooth curved surface centered on the central axis of the flow path tube 1.

The main part of the moving member 3 is set so as to move within the housing 1a located on the most upstream side of the housings 1a, 1b, 1c constituting the flow path pipe 1, and the outside of the moving member 3 is set. The annular air passage area (throttled area) formed between the edge member 3a and the inner peripheral wall surface 1a1 of the housing 1a increases so that the moving member 3 moves toward the downstream side. Is formed such that its cross-sectional area becomes wider toward the downstream side in the range in which the main part of the moving member 3 moves. Moreover, the inner peripheral wall surface 1a1 of the housing 1a is adjusted so that the movement amount of the moving member 3 and the increase / decrease in the air passage area have a predetermined functional relationship.

The upstream air inlet end portion 1A of the housing 1a has a minimum air passage area between the outermost edge portion 3a of the moving member 3 and the inner wall surface 1a1 of the housing 1a. The fully closed stopper 1a2 that regulates the fully closed position of the moving member 3 (almost zero) is positioned on the central axis by three ribs 1a3 extending in the central axis direction of the housing 1a from the inner peripheral wall surface 1a1 of the housing 1a. It is integrally formed with the housing 1a in a state of being supported by (see FIG. 6). When the moving member 3 is in the fully closed position, the apex of the moving member 3 which is set on the central axis of the housing 1a comes into contact with the fully closing stopper 1a2. Each rib 1a3 has a streamlined cross-sectional shape so as not to disturb the flow of air.

Further, a bypass passage 1a4 for bypassing the moving member 3 of the air flow passage 2 is formed in the housing 1a, and a bypass screw 4 for adjusting the amount of bypass air passing through the bypass passage 1a4 is formed in the bypass passage 1a4. The bypass passage 1a4 is provided so as to be able to move forward and backward. That is, the threaded portion 1a41 is formed on the inner peripheral wall surface of the bypass passage 1a4, and the screw 4 is screwed in or unscrewed to move the bypass screw 4 forward and backward in the bypass passage 1a4. An O-ring 5 is set between the bypass screw 4 and the inner peripheral wall surface of the bypass passage 1a4 in order to secure the seal at this portion. By adjusting the amount of air passing through the bypass passage 1a4, the air-fuel ratio of the air-fuel mixture supplied to the engine (not shown) during idling is adjusted.

By the way, the moving member 3 is set to be housed in the outer cylinder 3 and the outer cylinder 3b having an outer diameter smaller than the diameter of the cylindrical outer edge portion 3a extending in the downstream direction along the air flow direction. The inner cylinder 3c is integrally formed. Both the outer cylinder 3b and the inner cylinder 3c are centered on the central axis of the housing 1a, and the outer cylinder 3b and the inner cylinder 3c
A predetermined interval is set between and. The outer cylinder 3
Both of b and the inner cylinder 3c are closed at the upstream end by the moving member 3 and open at the downstream end.

Further, a shaft 3d extending in the downstream direction, which coincides with the central axis of the housing 1a, is integrally connected and fixed to the moving member 3.

Next, the housing 1b has four ribs 1b1 extending from the inner peripheral wall surface of the housing 1b in the central axis direction of the housing 1b.
(See FIG. 7), the cylindrical large-diameter cylindrical portion 1b2 supported by the rib 1b1, the intermediate cylindrical portion 1b3 provided so as to be housed in the large-diameter cylindrical portion 1b2, and the intermediate cylindrical portion 1b3. A small-diameter cylindrical portion 1b4 provided so as to be surrounded by is integrally formed. The large diameter cylindrical portion 1b
2, the intermediate cylindrical portion 1b3, and the small diameter cylindrical portion 1b4 are all formed around the central axis of the housing 1b, and the inner diameter of the large diameter cylindrical portion 1b2 is the outer cylinder 3b of the moving member 3.
Slightly larger than the outer diameter of the moving member 3, the outer diameter of the intermediate cylindrical portion 1b3 is smaller than the inner diameter of the outer cylinder 3b of the moving member 3, the inner diameter is larger than the outer diameter of the inner cylinder 3c of the moving member 3, and the small-diameter cylindrical portion 1b4. The outer diameter of is smaller than the inner diameter of the inner cylinder 3c of the moving member 3.

The small-diameter cylindrical portion 1b4 communicates in the axial direction, and the shaft 3d penetrates on the central axis thereof. The small-diameter cylindrical portion 1b4 has two sets of bearing portions 6a, which are ball bearings,
6b is held by a retainer 7 and fixed to the inner peripheral side thereof, and the shaft 3d is moved in the direction of the central axis by a bearing 8 including bearings 6a and 6b, a retainer 7, and a small diameter cylindrical portion 1b4. It is supported freely. In the bearing 8, the bearings 6a and 6b are set in series in the cage 7, and the bearings 6a and 6b are biased in opposite directions by a spring 9 set between them. The bearing portion 6a is held in contact with the end portion of the retainer 8, and the bearing portion 6b is held in contact with the ring-shaped holder engaged with the retainer 7.

The large-diameter cylinder portion 1b2 and the outer cylinder 3b of the moving member 3 are set so that the outer cylinder 3b is fitted into the large-diameter cylinder portion 1b2 via a predetermined appropriate clearance, that is, a minute gap. The outer cylinder 3b is configured to move within the large-diameter cylindrical portion 1b2 according to the movement of the moving member 3 from the fully closed state to the fully opened state. The downstream side of the large-diameter cylindrical portion 1b2 is sealed to the air passage 2 by a cover 1c1 which is integrally formed with a housing 1c, which will be described later. Therefore, the space formed by the large-diameter cylindrical portion 1b2 and the outer cylinder 3b is large. An air damper chamber 10 for communicating with the air passage 2 only by the clearance portion between the diameter cylindrical portion 1b2 and the outer cylinder 3b, and for stabilizing the fluctuation of the moving member 3 due to the pulsation of the air flow or the sudden change of the air flow rate is configured. Has been done.

In the air damper chamber 10, the moving member 3 is in the fully closing direction,
That is, the coil spring 11 that presses in the direction opposite to the air flow direction is set, and one end of the spring 11 abuts on the bottom of the annular groove between the outer cylinder 3b and the inner cylinder 3c of the moving member 3, The other end is an annular slider 12 set between the intermediate cylindrical portion 1b3 and the small diameter cylindrical portion 1b4.
Is in contact with. The spring 11 is guided by the outer peripheral wall surface of the inner cylinder 3c. By the way, a screw portion 1b41 is formed on the outer peripheral wall surface of the small-diameter cylindrical portion 1b4, and the slider 12 is engaged with the screw portion 1b41. By adjusting the position of the slider 12, the spring 11 with respect to the moving member 3 is adjusted. The pressing force is adjusted. In order to adjust the pressing force of the spring 11, a plurality of holes 12a are annularly formed on the downstream side surface of the slider 12 at regular intervals, and the large diameter cylindrical portion 1b2 and the intermediate cylindrical portion 1b are formed.
3. A partition wall 1b5 formed at each downstream end of the small-diameter cylindrical portion 1b4 is provided with a window 1b51 communicating with the partition wall 1b5 in an arc shape corresponding to the hole 12a (see FIG. 7).
For adjustment, a jig (not shown) is provided through the window 1b51 and the hole 12a is formed.
And the slider 12 is rotated to move the slider 12 back and forth along the screw portion 1b41. An O-ring 13 for fixing the position of the slider 12 is set between the slider 12 and the intermediate cylindrical portion 1b3.

An intake air temperature sensor 14 is set on the rib 1b1 and is housed in a metal cap 14a integrally molded so that a spherical tip of the housing 1b protrudes upstream when molding the housing 1b. , Lead wire 14b is connected.

Further, a connector 1b6 is formed on the housing 1b, and a plurality of pin 15 made of a conductor for taking out a signal is molded together with the pin holding member 15a via the inside of the rib 1b1 so that one end of the connector 1b6 projects into the connector 1b6. It is fixed. The other end of the pin 15 is connected to the lead wire 14b of the intake air temperature sensor 14, and is also connected to a sensor (potentiometer 18) that detects a displacement amount of the moving member 4 and converts the displacement amount into an electric signal, which will be described later. The pin 15 is first molded and fixed to a pin holding member 15a made of resin in an L-shape, and the pin 15 held by the pin holding member 15a is fixed by molding at the time of molding the housing 1b or the like so as to interpose the inside of the rib 1b1. .

The lead wire 15b of the intake air temperature sensor 14 is provided with a rubber-made lead wire holding member 14b1 so that the lead wire 15b does not play in the rib 1b1 of the intake air temperature sensor 14.
It is equipped corresponding to. The lead wire 14b is guided by a groove 16 formed between an arc-shaped ridge 1b7 and an annular ridge 1b8, which are integrally formed on the downstream side surface of the partition wall 1b5 when the housing 1b is formed, and one end of the pin 15 is guided. It is connected to the. The lead wire holding member 14b1
Is partially fitted in the raised portion 1b8, and is guided to the groove 16 portion by the lead wire holding member 14b1.

Further, a stud bolt 17 is molded and fixed to the partition wall 1b5 so that its tip projects to the downstream side surface of the partition wall 1b5, and a metal potentiometer boulder 19 holding a potentiometer 18 has a plurality of washers 21 with a nut 20. It is fixed to the stud bolt 17 through the stud bolt 17 (see FIG. 8).

The potentiometer 18 is held on a holder 19 so as to be parallel to the axis 3d of the moving member 3. By the way, the potentiometer 18 is held on the holder 19 between the potentiometer 18 and the holder 19 by using the double-sided tape 18a.
Is set to adhere to the potentiometer 18 and the holder 19, and the three protrusions 19a formed on the holder 19 are set.
And a hole 19b formed at a position facing the protrusion 19a.
It is held by a U-shaped leaf spring 22 that is fitted in the
The potentiometer 18 is pressed in the direction to hold it in the horizontal direction, and the push-back portion 22a of the leaf spring 22 holds it in the vertical direction.

A predetermined circuit pattern is set on the surface of the potentiometer 18, and the circuit pattern is the pin 15
Is electrically connected to one end of.

A slider 24, to which a brush 23 that slides in accordance with the displacement of the shaft 3d on the circuit pattern of the potentiometer 18, that is, the movement of the moving member 3, is provided at the end of the shaft 3d that passes through the bearing 8 is provided. (See FIG. 8).
The end portion of the portion of the shaft 3d penetrating the bearing 8 when the moving member 3 is fully closed and projecting to the downstream side is threaded and chamfered, and the slider 24 is chamfered. The stopper plate 25 set on the upstream side of the slider 24 of the shaft 3d, the spring 26 set between the stopper plate 25 and the slider 24, and the downstream side of the shaft 3d. The position of the slider 24 on the shaft 3d can be adjusted by the nut 27.

As described above, since the brush 23 of the slider 24 is slid on the circuit pattern of the potentiometer 18 to detect the moving amount of the moving member 3, the moving member 3 is detected.
It is necessary to prevent rotation about the central axis of. Therefore, the end of the rivet 28 provided by fitting or screwing at the tip of the projection 7a extending upstream from the end of the retainer 7 holding the bearings 6a, 6b is inside the inner cylinder 3c of the moving member 3. By being configured to slide in the guide groove 3c1 which is linearly formed on the peripheral wall surface along the moving direction,
The rotation of the moving member 3 is prevented.

In the housing 1c, a cover 1c1 for accommodating the potentiometer 18 and the like set on the downstream side of the partition wall 1b5,
A rib 1c2 that supports the cover 1c1 is integrally formed. The cover 1c1 has a bell-like shape with an opening on the upstream side, and is shaped so as not to disturb the flow of passing air as much as possible. The upstream opening 3 of the cover 1c1 has an inner diameter that substantially matches the outer diameter of the raised portion 1b8 formed on the housing 1b side, and a step 1c11 is formed on the inner diameter side of the opening end. An annular space is provided in which an O-ring 29 for ensuring a seal between the raised portion 1b8 and the opening of the cover 1c1 is set. The rib 1c2 extends in the central axis direction of the housing 1c and is smoothly connected to the outer peripheral surface of the cover 1c1. Four ribs 1c2 are formed corresponding to the ribs 1b1 set in the housing 1b.
The downstream side surface of b1 and the upstream side surface of the rib 1c2 of the housing 1c are aligned so that the assembly of both ribs 1b1 and 1c2 has a streamlined cross-section (see FIG. 9) to maximize the air flow. I try not to disturb.

Therefore, the cover 1c5 constitutes a potentiometer chamber 30 in which the potentiometer 18 and the like are housed. In the potentiometer chamber 30, the potentiometer 18 is installed.
The end portion of the shaft 3d having the slider 24 provided with the brush 23 that slides on the circuit pattern is displaced on the central axis line according to the movement of the moving member 3. Then, one end of the pin 15, that is, the end of the intake temperature sensor 14 on the side electrically connected to the lead wire 14 b and the potentiometer 18 projects into the potentiometer chamber 30.

The rib 1c2 of the housing 1c is formed in order to improve the accuracy of assembly of the housing 1b and the housing 1c in the rotational direction.
One of the protrusions 1c3 is set on the end face side of the rib 1c2 which is connected to the housing 1b on the housing 1c side.
Further, a groove 1b9 corresponding to the protrusion 1c3 is formed in the housing 1b along an inner peripheral wall surface inside the rib 1b1 of the housing 1b on the end face side where the housing 1c is connected to one of the ribs 1b1 of the housing 1b.

In the gas flow rate measuring device 100 having the above configuration,
When a predetermined air flow rate Q flows through the air flow path 2, the moving member 3
A pressure difference is generated in the upstream and downstream of the
Against the pressing force of the moving member 3, it moves linearly in the downstream direction from the fully closed position regulated by the fully closed stopper 1a2, and moves to the outer edge portion 3 of the moving member 3.
a and the inner peripheral wall surface 1a1 of the housing 1a are widened, and the pressure received by the upstream side surface of the moving member 3 and the pressing force of the spring 11 which becomes the air passage area necessary for the air flow rate Q to flow. The moving member 3 moves to a position where is balanced. In accordance with the movement of the moving member 3, the shaft 3d connected to the moving member 3 is displaced downstream on the central axis by the distance moved by the moving member 3, and the downstream end of the shaft 3d by the displacement amount x. The brush 23 of the slider 24 set in the part is displaced on the circuit pattern of the potentiometer 18, and the displacement amount x is converted into an electric signal by the potentiometer 18 and output to the outside via the pin 15. . Here, there is a predetermined functional relationship between the air flow rate Q and the air passage area, and the air passage area and the movement amount of the moving member 3,
That is, the inner peripheral wall surface 1a1 of the housing 1a is adjusted so that a predetermined functional relationship is established between the moving distance of the moving member 3 and the electric signal converted by the potentiometer 18 represents the air flow rate Q. become.

Further, in the above-described configuration, air is ventilated between the inside and the outside of the air damper chamber 10 only at the clearance portion between the outer cylinder 3b of the moving member 3 and the large cylindrical portion 1b2 fixedly set in the housing 1b. The vibration of the moving member 3 due to the pulsation of the air flow is suppressed, and the fluctuation of the moving member 3 is stabilized against the stepwise change of the air flow rate, and the behavior of the moving member 3 such as excessive overshooting is suppressed. Suppressed.

Therefore, according to the above configuration, since the movement of the moving member 3 is linear and parallel to the air flow in the air flow path 2, the pressure receiving area of the moving member 3 does not change even if the flow rate changes. Therefore, it is extremely easy to set the movement amount of the moving member 3 from the low flow rate region to the high flow rate region, that is, the change in the displacement amount of the shaft 3d to be uniform, and it is constant regardless of the change in the flow rate state. Measurement accuracy can be obtained.

Further, the displacement amount of the shaft 3d connected to the damper mechanism and the moving member 3 for suppressing vibration due to pulsation of the air flow of the moving member 3 and excessive overshoot when the air flow rate suddenly changes is converted into an electric signal. The potentiometer 18 is the flow tube 1
Since it is set inside, the size can be made sufficiently smaller and more compact than the vane type, and therefore the mountability on the vehicle is improved.

Also, by setting the potentiometer 18 in the air flow path 2,
Since the data representing the air flow rate is taken out as an electric signal, it is extremely easy to secure the sealing property between the air flow path 2 and the external space.

Further, in the above configuration, the inner peripheral wall surface of each housing 1a, 1b, 1c (in particular, the inner peripheral wall surface 1a1 of the housing 1a) is
Since the outer cylinder 3b and the large-diameter cylindrical portion 1b2 for forming the moving member 3 and the air damper chamber 10 have a circular cross-sectional shape, sufficient dimensional accuracy can be secured by molding as compared with a rectangular shape. As a result, no additional work is required after molding, and the number of production steps can be reduced.

In the above configuration, the ribs 1b1 of the housings 1b and 1c are
Since the assembly 1c2 is formed in a streamlined shape, the rib 1
The disturbance of the air flow by b1 and 1c2 is sufficiently suppressed.

In the above configuration, the potentiometer 18 covers the cover 1c1.
Since it is housed in the potentiometer chamber 30 so that the air flow does not come into direct contact with the potentiometer 18, foreign matter in the air, moisture, etc. are prevented from adhering to the potentiometer 18, and In the above embodiment mounted on the engine, fuel, oil, carbon, etc. from the engine are prevented from adhering to the potentiometer 18, changes in measurement accuracy and durability are prevented, and sufficient initial characteristics can be maintained for a long period of time. become.

FIG. 10 shows another embodiment of the gas flow rate measuring device. The same parts as those in the above embodiment are designated by the same reference numerals and the description thereof will be omitted.

In the present embodiment, the fully closed stopper 31 that regulates the fully closed position of the moving member 3 is fitted into the stopper plate 25 fixed to the shaft 3d on the downstream side of the bearing 8 of the shaft 3d.
1 is made of an elastic material. The end surface of the bearing 8 on the downstream side of the bearing cage 7 serves as a stop surface.

With this configuration, the flow of the air hitting the upstream side surface of the moving member 3 can be obtained smoothly, the movement of the moving member 3 can be stabilized, and the pressure loss of the air flow can be reduced.

The fully closed stopper 31 may be fixed to the shaft 3d on the upstream side of the stopper plate 25 instead of being fitted into the stopper plate 25. Further, if the fully closed stopper 31 is fixed so that it can be moved back and forth with respect to the shaft 3d, the fully closed position of the moving member 3 can be finely adjusted.

FIG. 11 shows a main part of the embodiment of the gas flow rate measuring device, and shows a clearance portion between the outer cylinder 3b of the moving member 3 and the large diameter cylinder part 1b2 of the housing 1b. In this configuration, the large-diameter cylindrical portion 1b when the moving member 3 on the outer peripheral wall surface on the downstream side of the outer cylinder 3b is in the fully closed state.
A portion having a predetermined width and facing the inner peripheral wall surface of 2 serves as a clearance surface 32 that sets a clearance between the outer peripheral wall surface of the outer cylinder 3b and the inner peripheral wall surface of the large-diameter cylindrical portion 1b2. That is, the diameter of the outer peripheral wall of the outer cylinder 3b forming the clearance surface 32 is larger than that of the other outer peripheral wall surface of the outer cylinder 3b by a predetermined width, and only this clearance surface 32 is sufficiently higher than the other outer peripheral wall surface. It is formed with precision.

With this configuration, it is possible to reduce the clearance between the outer cylinder 3b and the large-diameter cylindrical portion 1b2 that determines the damping characteristic of the present device, and the guaranteed range of the dimensional accuracy of the outer cylinder 3b, and to stabilize the damping characteristic. Is very easy to obtain. Further, even if foreign matter in the air enters between the outer cylinder 3b and the large-diameter cylindrical portion 1b2, the width of the clearance surface 32 is sufficiently smaller than the size of the outer cylinder 3b. Is easily removed in accordance with the fluctuation of the above, and the risk that the movement of the moving member 3 is impaired due to the foreign matter being caught becomes extremely small.

The clearance surface 32 may be set on the large-diameter cylindrical portion 1b2 side.

In the above embodiment, the outer cylinder 3b is fitted inside the large-diameter cylindrical portion 1b2 with a predetermined clearance, and the large-diameter cylindrical portion 1b2 is fitted.
Although it was configured to move inside b2, it has a large diameter cylindrical portion 1b.
The outer cylinder 3b may be fitted inside the outer cylinder 36 with a predetermined clearance, and the outer cylinder 3b may move outside the large-diameter cylindrical portion 1b2.

Further, in the above embodiment, the potentiometer 18 is used to convert the displacement amount of the shaft 3d into an electric signal, but any other sensor can be used as long as it can convert the displacement amount of the shaft 3d into an electric signal. Alternatively, for example, a differential transformer or an optical non-contact displacement detection sensor can be used.

Further, although the above-mentioned embodiment describes the case where the air flow rate is measured by mounting on an automobile engine, the present measuring device can measure other gas flow rates.

According to the gas flow rate measuring device 100 as described above, since the pressure receiving area of the moving member 3 is constant regardless of the flow rate of the gas to be measured, the shaft 3 extending from the moving member 3 is fixed.
It is extremely easy to set the degree of change in displacement of d to be uniform from the low flow rate range to the high flow rate range, and it is possible to ensure constant measurement accuracy regardless of changes in the flow rate state. The movement of the moving member 3 causes the outer cylinder 3 as the first cylinder to move.
Since b is displaced along the second cylinder through a small gap with the large-diameter cylindrical portion 1b2 as the second cylinder, the moving member 3 has the configuration of the first cylinder and the second cylinder. With respect to the above, a damping function is actuated, vibration of the moving member 3 due to pulsation of the gas flow, excessive overshoot due to a sudden change in the gas flow rate, and the like can be suppressed, and this configuration is set in the gas flow path. Therefore, there is also an excellent effect that it becomes possible to make this device small and compact.

Next, a mounting structure of the gas flow rate measuring device 100 will be described. 1 and 2 show an example of the mounting, and FIG. 2 is a view from the direction A in FIG. In FIG. 1 and FIG. 2, reference numeral 200 is an air cleaner having a built-in filter for letting air through before being measured by the gas flow rate measuring device 100. Gas flow measuring device 100
Is mounted on the air cleaner 200.

Next, the structure involved in mounting the gas flow rate measuring device 100 on the air cleaner 200 will be described in detail.

Of the three housings 1a, 1b, 1c forming the outer frame of the gas flow rate measuring device 100, the raised joints 1d, 1e are formed at both ends of the central housing 1b as described above. , Both joints 1
The portion sandwiched between d and 1e forms a groove portion 1f having a smooth cylindrical surface with a smaller diameter than the joint portions 1d and 1e.

The gas flow rate measuring device 100 is fixed on the air cleaner 200 in the housing 1b. Air cleaner 20
On the fixed surface of the gas flow rate measuring device 100 at 0, two first and second stays 201 and 202 are provided as protrusions on a line perpendicular to the axis of the housing 1b. The first and second stays 201 and 202 are arranged apart from the maximum diameter of the gas flow rate measuring device 100.

A lower holder 51 made of metal is installed on the first and second stays 201 and 202, and a first end portion 51a of the lower holder 51 is provided on the upper surface of the first stay 201. The second end 51b of the lower holder 51 is fixed to the upper surface of the protrusion 202 with bolts 54 and 55, respectively.
The lower holder 51 has a shape in which both end portions 51a and 51b are parallel to the mounting surfaces of the first and second stays 201 and 202 of the air cleaner 200, and the portion between the both end portions 51 and 51b is of the gas flow rate measuring device 100. It is formed in an arc shape so as to fit in the groove portion 1f forming the outer periphery of the intermediate housing 1b. The mounting surfaces of the first and second stays 201 and 202 are formed sufficiently wider than the diameters of the bolts 54 and 55.

An upper holder 52 made of metal is fixed to both ends 51a and 51b of the lower holder 51 so as to sandwich the housing 1b together with the lower holder 51. One end of the upper holder 52 is formed into a U-shaped key portion 52a as shown in FIG. 3, and the two locking holes 51a1 and 51a2 formed in the first end portion 51a of the lower holder are provided with this key. The part is fitted and locked. Also, the upper holder 52
The other end 52b of is fixed to the second end of the lower holder 51 with a screw 53. An arcuate bulge 52c is formed in the middle of the upper holder 52 so that the length of the upper holder 52 in the circumferential direction of the housing 1b can be elastically changed. The upper holder 52 is also fitted in the groove portion 1f formed in the circumferential direction of the housing 1b similarly to the lower holder 51. Further, as described above, on the outer periphery of the housing 1b,
Since the connector 1b6 is molded, the upper holder 5
A window portion (not shown) is formed in 2 so as not to interfere with the connector 1b6. The ends of the holders 51 and 52 along the circumferential direction are bent in accordance with the shapes of the joints 1d and 1e so as to wrap the joints 1d and 1e of the housing.

Therefore, since the widths of the two holders 51 and 52 are approximately the same as the length of the intermediate housing 1b, the gas flow rate measuring device 100 can be firmly fixed to the air cleaner 200. Further, since the groove portion 1f is formed in the housing 1b and the holders 51 and 52 are engaged with the groove portion 1f, rattling of the gas flow rate measuring device 100 due to engine vibration, particularly in the axial direction, can be eliminated. . Also, a U-shaped key portion 52 at one end of the upper holder 52
a is the locking hole 51 of the lower holder utilizing the elasticity of the metal.
Since it can be fixed by fitting it into a1 and 51a2, the mounting work can be performed easily. Further, it is possible to change the length of the upper holder 52 and automatically adjust the tightening force by elastically deforming the bow-shaped bulge portion 52c formed on the upper holder 52. Instead, the measuring device 100 can be firmly fixed to the air cleaner 200 by exerting a strong force during vibration.

In this way, the gas flow rate measuring device 100 can be integrally fixed by directly mounting it on the air cleaner 200, and the engine can be made more compact. Further, according to the present embodiment, since the hollow portion 203 is formed on the surface of the air cleaner 200 facing the lower holder 51 so as to match the shape of the lower holder 51 (that is, the shape of the housing 1b), the gas flow rate measurement is performed. The mounting height of the device 100 can be reduced, and the device can be made more compact.

On the other hand, a concave portion 1A1 for preventing movement in the axial direction by forming a grommet over the entire circumference is formed in the air inlet end portion 1A of the housing 1a on the most upstream side of the gas flow rate measuring device 100. There is. The inlet end 1A is inserted into the air outlet end 204 of the air cleaner 200 with the grommet 60 fitted in the recess 1A1. The air outlet end portion 204 is formed so as to be oriented in a direction perpendicular to the recessed portion 203 of the air cleaner 200, and serves as an outlet for air before measurement which is passed by a filter in the air cleaner 200. The grommet 6 is attached to the inner peripheral wall of the outlet end portion 204 of the air cleaner 200.
A step portion 204a is formed for appropriately compressing 0 and for restraining the insertion of the measuring device 100.

Next, the grommet 60 will be described. Grommet 6
Reference numeral 0 is an elastic member such as rubber and has a ring shape, and its cross section is shown in FIG. In FIG. 4, grommet 60
The inner peripheral surface 61 was formed as a smooth cylindrical surface having no protrusions. The diameter of the inner peripheral surface 61 of the grommet 60 before fitting is slightly smaller than the diameter of the recessed portion 1A1 on the outer circumference of the housing 1a so that the housing 1a can be fitted into the housing 1a without a gap during fitting. In addition, grommet 60
An adhesive may be applied between the housing and the housing 1a. Further, on the outer circumference of the grommet 60, a tongue portion 62 as a first raised portion having a diameter larger than the inner circumference of the stepped portion 204a of the air outlet end portion 204 of the air cleaner 200, and the same diameter as the stepped portion 204a or A positioning portion 63 as a second raised portion having a slightly smaller diameter is integrally formed. The tongue portion 62 is located on the upstream side and the positioning portion 63 is located on the downstream side, and the inlet end 1A of the gas flow rate measuring device 100 is located at the air cleaner 200.
The tongue portion 62 and the positioning portion 63 are formed with a sufficient space so that the tongue portion 62 does not overlap the circumference of the positioning portion 63 when the tongue portion 62 is inserted into the outlet end portion 204. Tongue 6
Reference numeral 2 is a shape in which the cross section becomes narrower toward the outermost periphery, and the tip portion 62a thereof is slightly inclined toward the positioning portion 63 side even before insertion. The outer peripheral portion 63a of the positioning portion 63 is formed into a smooth cylindrical surface.

When the inlet end 1A of the gas flow measuring device 100 is inserted into the outlet end 204 of the air cleaner 200, the tongue portion 62 on the outer periphery of the grommet 60, which is press-fitted into the recess 1A1 of the gas flow measuring device 100, is compressed. Grommet 6
0 is the end portion 62a of the tongue portion 62 of the grommet 60 which is accommodated in the recess 1A1 and the outlet end portion 2 of the air cleaner 200.
While facing the inner peripheral wall of the stepped portion 204a of No. 04, it faces in the direction opposite to the insertion direction. Due to the compressive deformation of the tongue portion 62, the grommet 60 is compressed in the radial direction to perform a sealing action,
At the connecting portion between the air cleaner 200 and the measuring device 100, the exchange of air with the outside can be completely shut off.

Further, the pressure at the outlet end portion 204 of the air cleaner 200 is always lower than the outside air due to the pressure loss when the intake air flow passes through the air filter in the air cleaner 200. By the way, since the tongue portion 62 of the grommet 60 is inclined toward the downstream side, that is, in the direction of the communicating portion with the outside of the air cleaner 200,
Due to the pressure difference, the tongue portion 62 is strongly pressed from the downstream side, and further strongly presses the inner periphery of the air cleaner 200, thereby improving the airtightness during engine operation. The outer circumference of the positioning portion 63 formed on the grommet 60 is also fixed against variations in the inner diameter of the stepped portion 204a of the outlet end 204 of the air cleaner 200, shaft misalignment during assembly, vibration during operation, and the like. The surface 63a allows the air cleaner 200 and the measuring device 10
It is possible to regulate the positional deviation from 0 in the radial direction. Therefore, the positioning portion 63 can keep the deviation of the flow path axis within the allowable range, the amount of deformation of the tongue portion 62 can be made substantially constant, and the durability of the grommet 60 itself is very high. It will be excellent and will have excellent airtightness for many years. Further, as described above, the positioning portion 63 and the tongue portion 62 are configured so as not to interfere with each other even when the tongue portion 62 is maximally deformed. Therefore, the inside of the air cleaner 200 and the external space are always kept by the tongue portion 62. As a result of being partitioned, the above-mentioned external pressure can be exerted on the tongue portion 62 during operation to exert a strong sealing property.

In the embodiment described above, the installation of the inlet portion of the gas flow rate measuring device 100 having the seal portion in the structure for mounting the gas flow rate measuring device 100 on the air cleaner 200 and the fixed portion of the gas flow rate measuring device 100 with the air cleaner 200 are performed. Since they are located at different positions, the work is easy, the assembling property is improved, and the structure is simplified.

〔The invention's effect〕

According to the present invention, taking advantage of the features of a small gas flow rate measuring device, it can be easily mounted and coupled to a box such as an air cleaner. Further, there is an excellent effect that the fixing of the both is sure and easy and the sealing action does not deteriorate.

Further, by doing so, the gas flow rate measuring device can be directly attached to the box body, and the engine can be made compact.

[Brief description of drawings]

FIG. 1 is a front view showing an embodiment of a mounting structure of a gas flow rate measuring device according to the present invention, FIG. 2 is a view taken in the direction of the arrow A in FIG. 1, and FIG. FIG. 4 is a perspective view of the part, and FIG.
FIG. 5 is a sectional view of an essential part of the drawing, FIG. 5 is a sectional view of one gas flow rate measuring device to which the mounting structure according to the present invention is applied, and FIG. 6 is A of FIG.
FIG. 7 is a view from the direction B in the state where the housing 1c of FIG. 5 is removed, and FIG. 8 is a partial cross-sectional view taken along the line CC of FIG. Figure is DD of Figure 8.
Sectional views taken along the line, FIG. 10 and FIG. 11 are sectional views of another embodiment of the gas flow rate measuring apparatus to which the mounting structure according to the present invention is applied. DESCRIPTION OF SYMBOLS 1 ... Flow path pipe, 1a, 1b, 1c ... Housing, 1f ... Groove part, 2 ... Air passage, 3 ... Moving member, 3b ... Outer cylinder, 3d
... shaft, 8 ... bearing, 10 ... air damper chamber, 11 ... spring, 18 ... potentiometer, 51 ... first holder,
51a ... 1st end part, 51a1, 51a2, ... Hole part, 5
1b ... 2nd end part, 52 ... 2nd holder, 52a ... One end (key part), 52b ... Other end, 52c ... Swelling part, 53,
54, 55 ... Screw, 60 ... Grommet, 62 ... First ridge, 63 ... Second ridge, 1A ... Gas inlet opening end,
1A1 ... Recessed part, 100 ... Gas flow rate measuring device, 200 ... Box body, 204 ... Gas outlet opening end part.

Claims (1)

[Claims] 1. A mounting structure for a gas flow rate measuring device, wherein an air flow outlet end portion of a box body through which air drawn into a vehicle engine is connected to an air flow inlet end portion of the box body. The measuring device has a flow path tube, and the flow path tube has a plurality of housings which are bonded and sealed to each other at a joint portion, and each joint portion raises an outer peripheral portion of each housing to increase a wall thickness. In the housing, a portion adjacent to the joint portion has a cylindrical surface having a diameter smaller than that of the joint portion, and a stay is provided on the fixed surface of the gas flow rate measuring device in the box body. A holder is attached to the stay, and the holder has a central portion formed in an arc shape in contact with a portion of the housing having the cylindrical surface, and extends along the circumferential direction of the holder. The ends are the above It is bent according to the shape of the joint so as to wrap the joint of the ging, and the air outlet end of the box body and the air inlet end of the gas flow rate measuring device via a grommet. A mounting structure for a gas flow measuring device, wherein the grommet is connected by elastic deformation.